CN101323669B - PTFE powder and manufacturing method of PTFE powder - Google Patents

Abstract

The invention provides a method for producing polytetrafluoroethylene powder and polytetrafluoroethylene molding powder. The polytetrafluoroethylene powder is characterized in that the surface roughness Ra of the molded body a1 for measurement is less than 0.92 μm. The surface roughness Ra, tensile strength and/or tensile elongation of the molded body obtained from the polytetrafluoroethylene powder are improved compared with the past, and its dielectric breakdown strength is good, and it can also have excellent apparent density and/or powder flowability.

Description

PTFE powder and manufacturing method of PTFE powder

This application is a divisional application. The international application number of the original application is PCT/JP02/11035, the Chinese national application number is 02821101.4, and the application date is October 24, 2002. The invention name is "PTFE powder and PTFE molding powder. Manufacturing method".

technical field

The present invention relates to polytetrafluoroethylene powder and a method for producing polytetrafluoroethylene molding powder used for manufacturing polytetrafluoroethylene molding powder, which can improve the surface smoothness and tensile strength of moldings. And/or the tensile elongation is improved compared with the conventional one, and the dielectric breakdown strength is excellent, and the apparent density and/or powder fluidity may also be excellent if necessary.

Background technique

Polytetrafluoroethylene (PTFE) is a thermoplastic resin with excellent heat resistance, corrosion resistance, weather resistance, electrical insulation, and non-adhesiveness, and has a wide range of uses. However, the melt viscosity of PTFE is extremely high. High, the conventional plastic molding processing methods used by ordinary thermoplastic resins with low melt viscosity, such as general extrusion molding and injection molding, have not been able to be used.

For this reason, the molding of PTFE generally adopts the sintering molding method instead of the conventional plastic molding processing method. The resin sintering molding method preforms the resin molding powder, and then heats the obtained preform to a temperature not lower than the melting point of the resin to sinter the resin particles to obtain a molded body.

As the sintering molding method of PTFE, there are compression molding method, press molding method, and the like.

Compression molding generally fills PTFE molding powder into a mold and compresses it to obtain a preform, then puts the preform into a furnace for sintering, and then cools it to complete the molding.

The stamping molding method intermittently supplies PTFE molding powder from one end, and presses the supplied PTFE molding powder into the cylinder with each feeding portion with a piston (shooting rod), so that each pressed body is lowered, and the same as the previous one. A supply of press-fit bodies is joined, and then fused by calcination to obtain a joint body. After cooling, the joint body is extruded from the other end of the cylinder.

If the powder for molding is pulverized after polymerization of PTFE, these sintering molding methods of PTFE are generally easy to obtain a dense molded body without voids, and the surface smoothness, tensile strength, tensile elongation, and high pressure of the molded body Physical properties such as electrical insulation tend to be good.

On the other hand, the powdered product after PTFE polymerization is generally poor due to its apparent density, powder fluidity and other powder properties, and the powder for molding will agglomerate in the hopper or small diameter cylinder of the molding machine to form a bridge , leading to non-uniform filling in the mold or cylinder, etc., there is a tendency that the workability is insufficient.

In addition, the apparent density of the pulverized product after PTFE polymerization is low, and the volume of the molding powder per unit weight is large, so it is difficult to realize the miniaturization of the mold or cylinder. productivity.

In order to improve the apparent density and powder fluidity of the pulverized product after PTFE polymerization, granulation was considered. In this way, although the apparent density and powder fluidity of the obtained granulated product are improved, there is a problem that a shearing force is applied during granulation, and in this case, the physical properties of the obtained molded product are lowered.

For the purpose of improving the powder fluidity and apparent density of the pulverized product, Japanese Patent Application No. 5-180694 discloses granulated PTFE, which uses fillers and PTFE powder with an average particle size of less than or equal to 20 μm as raw materials , but there is no description in this gazette that the molded article has excellent physical properties.

As a granulation method of PTFE, for example, the following methods are disclosed in JP-A-10-259252 and JP-A-10-316763, etc., in which 99 mol% to 99.999 mol% of tetrafluoroethylene and 1 mol of % to 0.001 mol% of perfluorovinyl ether copolymerization, in the presence of surfactants, the obtained PTFE polymerized powder or pulverized product with an average particle diameter of less than 100 μm is granulated in water.

As mentioned above, conventional PTFE molding powder tends to have poor physical properties when the powder has good physical properties, and poor physical properties when the molded product has good properties. Because of this tendency, it is common to select which characteristics to focus on depending on the application.

For example, for general-purpose products such as spherical valve seats that have been mass-produced in the past, the operability and processability during molding are more important than the physical properties of the molded body. Therefore, even if the physical properties of the molded body are somewhat inferior, the powder Powder for molding with good physical properties. However, even such general-purpose products and the like need to improve the physical properties of the molded article.

For the purpose of improving the physical properties of the molded body by reducing the residual amount of impurities, the WO96/28498 publication discloses a method for preparing PTFE molding powder, which is characterized in that the PTFE coarse particles obtained by suspension polymerization are pulverized in a wet state, and then Clean up.

For the purpose of improving the bending fatigue resistance of the physical properties of the molded article, for example, WO93/16126 discloses a PTFE molding powder, which has a heat of crystallization measured by a differential scanning calorimeter (DSC) of 18.0 to 25.0 J/g, The specific surface area is 0.5-9.0m ² /g, the average particle diameter is less than or equal to 100μm, and the content of perfluoro(alkyl vinyl ether) units is 0.01% by weight to 1% by weight. The molded product obtained by using this powder has a specific curvature life and creep resistance. However, this publication does not describe the surface roughness Ra, tensile strength, tensile elongation, powder fluidity, etc. of the powder, and does not describe the pulverization method.

PTFE molded products whose physical properties are more important than powder properties are large items with a diameter of usually 200mm or more. From an economic point of view, there is a high demand for molding large-scale objects, and the pre-molding of large-scale objects is limited by the pressure applied, so even if the physical properties of the powder are somewhat poor, it must be able to obtain a certain quality of molding with a small pressure Physical properties.

In recent years, the use of PTFE has expanded to the field of semiconductor manufacturing and the like, and it has been gradually applied to high-voltage insulating materials such as insulating gaskets and insulating nozzles. In the semiconductor-related field, high molded product properties such as excellent dielectric breakdown strength are required in nature, and surface smoothness is required to avoid chipping in order to prevent contamination of the product.

Contents of the invention

In view of the above-mentioned problems, the object of the present invention is to provide a polytetrafluoroethylene powder and a polytetrafluoroethylene molding powder manufacturing method, wherein the powder can make the surface roughness Ra, tensile strength and/or tensile elongation of the molded body Compared with the previous ones, the strength has been improved, the dielectric breakdown strength has been improved, and it can also have excellent apparent density and/or powder flowability as required.

The present invention relates to a polytetrafluoroethylene powder characterized in that the surface roughness Ra of the molded body a1 for measurement thereof is less than 0.92 μm.

The present invention relates to a polytetrafluoroethylene powder characterized by having an apparent density of 0.45 g/cm ³ or more and a molded body for measurement a1 having a surface roughness Ra of less than 1.9 μm.

The present invention relates to a polytetrafluoroethylene powder characterized by having a fluidity of 0.5 times or more and a molded body for measurement a1 having a surface roughness Ra of less than 1.9 μm.

The present invention relates to a polytetrafluoroethylene powder characterized by having a fluidity of 0.5 times or more, an apparent density of 0.45 g/cm ^{3 or more} , and a molded body for measurement a1 having a surface roughness Ra of less than 1.9 μm.

The present invention relates to a polytetrafluoroethylene powder characterized by having an apparent density of 0.45 g/cm ³ or more and a dielectric breakdown voltage of 9.1 kV or more of the molded body a2 for measurement.

The present invention relates to a polytetrafluoroethylene powder characterized by having a fluidity of 0.5 times or more and a dielectric breakdown voltage of the molded body a2 for measurement of 9.1 kV or more.

The present invention relates to polytetrafluoroethylene powder characterized by having a fluidity of 0.5 times or more, an apparent density of 0.45 g/cm ^{3 or more} , and a dielectric breakdown voltage of 9.1 kV or more for the molded body a2 for measurement.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body a3 for measurement thereof has a tensile strength of 58.7 MPa or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the tensile elongation of the molded body a3 for measurement is 556% or more.

The present invention relates to a polytetrafluoroethylene powder characterized by having an apparent density of 0.45 g/cm ³ or more and a tensile elongation of the molded body a3 for measurement of 431% or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body a1 for measurement has a surface roughness Ra of less than 1.5 μm and the molded body a3 for measurement has a tensile strength of 47.8 MPa or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body a1 for measurement has a surface roughness Ra of less than 1.2 μm and the molded body a3 for measurement has a tensile elongation of 423% or more.

The present invention relates to a polytetrafluoroethylene powder characterized by having an apparent density of 0.45 g/cm ^{3 or more} , a surface roughness Ra of the molded body a1 for measurement of less than 2.4 μm, and a tensile strength of the molded body a3 for measurement. The elongation is greater than or equal to 370%.

The present invention relates to a polytetrafluoroethylene powder characterized in that its fluidity is equal to or greater than 0.5, the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 0.5 μm. Equal to 370%.

The present invention relates to a polytetrafluoroethylene powder characterized by having a fluidity of 0.5 times or more, an apparent density of 0.45 g/cm ^{3 or more} , and a molded body for measurement a1 having a surface roughness Ra of less than 2.4 μm, The tensile elongation of the molded article a3 for measurement is 370% or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body for measurement a1 has a surface roughness Ra of less than 0.92 μm and the molded body for measurement a2 has a dielectric breakdown voltage of 10 kV or more.

The present invention relates to a polytetrafluoroethylene powder characterized by having an apparent density of 0.45 g/cm ^{3 or more} , a surface roughness Ra of the molded body a1 for measurement of less than 2.5 μm, and an insulating property of the molded body a2 for measurement. The destruction voltage is greater than or equal to 8.5kV.

The present invention relates to a polytetrafluoroethylene powder characterized in that its fluidity is equal to or greater than 0.5, the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is equal to or greater. 8.5kV.

The present invention relates to a polytetrafluoroethylene powder characterized by having a fluidity of 0.5 times or more, an apparent density of 0.45 g/cm ^{3 or more} , and a molded body for measurement a1 having a surface roughness Ra of less than 2.5 μm, The dielectric breakdown voltage of the molded body a2 for measurement is not less than 8.5 kV.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body a3 for measurement has a tensile strength of 47.8 MPa or more and the molded body a3 for measurement has a tensile elongation of 451% or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body a2 for measurement has a dielectric breakdown voltage of 11.5 kV or more and the molded body a3 for measurement has a tensile strength of 47.8 MPa or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body a2 for measurement has a breakdown voltage of 10 kV or more and the molded body a3 for measurement has a tensile elongation of 556% or more.

The present invention relates to a polytetrafluoroethylene powder characterized in that the molded body for measurement a1 has a surface roughness Ra of less than 1.2 μm, the molded body for measurement a3 has a tensile strength of 47.8 MPa or more, and the molded body for measurement The tensile elongation of a3 is greater than or equal to 423%.

The present invention relates to a polytetrafluoroethylene powder characterized in that the dielectric breakdown voltage of the molded body a2 for measurement is 10 kV or more, the molded body a3 for measurement has a tensile strength of 47.8 MPa or more, and the molded body a3 for measurement is equal to or greater than 47.8 MPa. The tensile elongation is greater than or equal to 451%.

The present invention relates to a method for producing a polytetrafluoroethylene molding powder characterized in that it is for producing a polytetrafluoroethylene molding powder which is a polytetrafluoroethylene molding powder formed by pulverizing unpulverized polytetrafluoroethylene powder. The manufacturing method is characterized in that the unpulverized polytetrafluoroethylene powder is formed from a polytetrafluoroethylene-based polymer obtained by suspension polymerization, and the polytetrafluoroethylene-based polymer is formed from non-modified polytetrafluoroethylene Vinyl fluoride and/or modified polytetrafluoroethylene are formed, and the pulverization is carried out without substantial fibrillation of the obtained particles.

The present invention will be described in detail below.

The present invention relates to polytetrafluoroethylene powder (PTFE powder).

The term "polytetrafluoroethylene" in the following specification is also referred to as PTFE, and PTFE is just a simplified form of the "polytetrafluoroethylene".

The "PTFE powder" in this specification is a powdery solid formed of a PTFE-based polymer, and means that it has the physical properties of a molded body or has the physical properties of a molded body and a powder.

The "PTFE-based polymer" is formed of modified PTFE and/or non-modified PTFE.

In this specification, "Powdered solid formed of PTFE-based polymer" is simply referred to as "PTFE powder", and the unspecified parts refer to the PTFE powder of the present invention, the following PTFE molding powder or the following PTFE ungrinded powder , means not limited to the PTFE powder of the present invention, the following PTFE molding powder or the following PTFE unpulverized powder PTFE-based polymer powdery solid.

In this specification, the "general powdery solid" refers to the raw powder after polymerization immediately obtained by polymerization and/or each of the raw powder after coarse pulverization, washing, drying, pulverization and granulation. The powder obtained after processing.

In this specification, the "primary powder after polymerization" refers to the powder formed by the polymer obtained by polymerization, which means that washing, coarse pulverization, drying, pulverization, granulation and/or Various processed powders heated to a temperature not lower than the melting point of PTFE-based polymers.

When the PTFE powder of the present invention is made into a molded body, the surface roughness Ra, tensile strength (TS) and/or tensile elongation (EL) are excellent, and compared with the previous PTFE powder, its surface roughness Ra, Both tensile strength and/or tensile elongation, respectively, are increased, and it may also have excellent apparent density and/or powder flowability as required.

In addition, when the PTFE powder of the present invention is made into a molded body, the molded body can have excellent dielectric breakdown voltage (BDV), and if necessary, can also have excellent surface roughness Ra, tensile strength and/or tensile elongation , can also have excellent apparent density and/or powder flowability as required.

In this specification, surface roughness Ra, dielectric breakdown voltage, tensile strength and/or tensile elongation are collectively referred to as "formed article physical properties". In this specification, apparent density and/or powder fluidity are collectively referred to as "powder physical properties".

In this specification, the surface roughness Ra is represented by the measured value of the molded body a1 for measurement, the dielectric breakdown voltage is represented by the measured value of the molded body a2 for measurement, and the tensile strength and/or tensile elongation are represented by the measured value of the molded body for measurement. The measured value of body a3 shows. In the case of the PTFE powder of the present invention, the molded body a1 for measurement, the molded body a2 for measurement and the molded body a3 for measurement in the measuring methods of the physical properties of each molded body below are obtained by using the PTFE powder of the present invention as the PTFE powder.

The PTFE powder of the present invention can make the surface roughness Ra of the molded body a1 for measurement less than, for example, 2.5 μm, so the molded body obtained from the PTFE powder of the present invention has a smooth surface as a whole and less unevenness on the surface. Therefore, the PTFE powder of the present invention having a small surface roughness Ra can be suitably used for molding of molded articles requiring surface smoothness, such as spherical valve seats.

The PTFE powder of the present invention having a small surface roughness Ra is excellent in surface smoothness, and even when it was previously necessary to smooth the surface by chipping or the like, it may not be necessary to perform surface smoothing treatment. Therefore, the PTFE powder of the present invention can be suitably used in the molding of molded products that do not include a chipping step in the manufacturing process but require smoothness of the surface, for example, molding of molded products such as seal rings without chipping.

The PTFE powder of the present invention with a small surface roughness Ra may not require surface smoothing such as chipping. In this case, it can be used for equipment and parts in the field of semiconductor manufacturing that require removal of impurities such as chips. And other molded products molding. The molded product used in the field of semiconductor manufacturing is not particularly limited, and examples thereof include large-sized thin plates used in semiconductors, various corner grooves, slide plates, and the like. Such oversized sheets are sometimes referred to as gauge gussets.

The surface roughness Ra of the molded body a1 for measurement is preferably less than 1.9 μm, more preferably less than 1.2 μm, more preferably less than 0.8 μm, and can be adjusted within the range according to different applications. When the surface roughness Ra is within the above range, it is usually greater than or equal to 0.5 μm, for example, it may be greater than or equal to 0.55 μm.

In the present specification, the surface roughness is a value obtained by the following method. 210g of PTFE powder is filled in a mold with a diameter of 50mm, kept at a molding pressure of 29.4MPa (300kgf/ ^cm2G ) for 5 minutes, and the resulting preform is heated from room temperature to 365°C, kept at 365°C for 5.5 hours, and then cooled at a rate of 50°C/hour, using a surface roughness measuring instrument manufactured by Tokyo Precision Instrument Co., Ltd., according to the centerline average roughness (Ra) method of JIS B 0601. The upper surface of the obtained molded body was measured, and the obtained value was the surface roughness. In the present specification, the molded article to be measured is referred to as "the molded article for measurement a1".

The PTFE powder of the present invention can make the dielectric breakdown voltage of the molded body a2 for measurement equal to or higher than 8.5 kV, so that the molded body obtained from the PTFE powder of the present invention can have excellent high-voltage insulation as a whole. Therefore, the PTFE powder of the present invention can be suitably used for molding high-voltage insulating materials such as insulating tapes or insulating gaskets of capacitors for high-voltage transformers, insulating ports for circuit breakers, and the like.

The dielectric breakdown voltage of the molded body a2 for measurement is preferably greater than or equal to 9.1kV, more preferably greater than or equal to 10kV, more preferably greater than or equal to 12kV, particularly preferably greater than or equal to 13kV, and can be adjusted within the stated range according to different applications. When the dielectric breakdown voltage is within the above range, it is usually less than or equal to 18kV, for example, it may be less than or equal to 15kV, and may even be less than or equal to 14kV.

In the present specification, the dielectric breakdown voltage is a value obtained by the following method. The PTFE powder of 210g is filled in the mold that diameter is 50mm, keeps 5 minutes under the molding pressure of 29.4MPa (300kgf/cm ² G), with the preform that obtains (diameter is approx. 50mm, thickness 50mm) from room temperature to 365°C, keep at 365°C for 5.5 hours, then cool at a rate of 50°C/hour, cut the obtained molded product to obtain slices with a thickness of 0.1mm, according to JIS K 6891 measures the obtained slices, and the obtained value is the dielectric breakdown voltage. In this specification, the 0.1-mm-thick slice which is the object of this measurement is referred to as "molded article a2 for measurement".

The PTFE powder of the present invention can make the tensile strength of the molded body a3 for measurement equal to or greater than 47.8 MPa, so when a tensile force is applied, the molded body obtained from the PTFE powder of the present invention has excellent mechanical strength as a whole.

Therefore, the PTFE powder of the present invention can be suitably used in the molding of molded articles that require high strength due to the need for stretching for embedding in instruments-apparatus, etc., such as molding of seal rings and the like. As the seal ring, it is suitable for both a seal ring with a slit that deforms when it is inserted into an appliance, or a ring-like rubber-like seamless ring with no slit on the ring.

In particular, from the standpoint of excellent mechanical strength, the PTFE powder of the present invention is also suitable for molding molded products such as spherical valve seats that must have tensile strength.

The tensile strength of the molded body a3 for measurement is preferably greater than or equal to 50 MPa, more preferably greater than or equal to 58.7 MPa, more preferably greater than or equal to 60 MPa, particularly preferably greater than or equal to 65 MPa, and can be adjusted within the stated range according to different uses. When the tensile strength is within the above range, it is usually less than or equal to 70 MPa, for example, it may be less than or equal to 66 MPa.

The PTFE powder of the present invention can make the tensile elongation of the molded body a3 for measurement greater than or equal to, for example, 370%, so when stretched, the molded body obtained by the PTFE powder of the present invention shows a larger elongation as a whole. Even if tension is applied during installation or processing of appliances, etc., it can prevent cutting.

Therefore, the PTFE powder of the present invention can be suitably used in the molding of molded articles that require a long elongation when embedded in appliances and the like, such as molding of seal rings and the like. As the sealing ring, as mentioned in terms of tensile strength, either a sealing ring with a slit on the ring or a seamless ring without a slit on the ring is applicable, but the latter can more fully exert the excellence of the tensile elongation.

The tensile elongation of the molded body a3 for measurement is preferably greater than or equal to 450%, more preferably greater than or equal to 500%, more preferably greater than or equal to 550%, particularly preferably greater than or equal to 600%, and can be within the range according to different uses Make adjustments. When the tensile elongation is within the above range, it is usually less than or equal to 650%, for example, it may be less than or equal to 630%.

In the present specification, the tensile strength and the tensile elongation are values obtained by the following method. The PTFE powder of 210g is filled in the mold that diameter is 50mm, keeps 5 minutes under the molding pressure of 300kgf/cm ² G, with the preform that obtains (diameter is about 50mm, thickness is 50mm) from room temperature to 365°C, maintained at 365°C for 5.5 hours, and then cooled at a rate of 50°C/hour, and cut the obtained molded product to obtain slices with a thickness of 0.3mm, using a JIS No. 3 dumbbell chisel According to JIS K 6891-58, the impact test piece was stretched at a tensile speed of 200mm/min, and the stress and elongation at the time of rupture were measured using an automatic recorder with a total load of 500kg. The values obtained were the tensile strength and Stretch elongation. In this specification, the test piece which is the object of this measurement is referred to as "molded article for measurement a3".

The PTFE powder of the present invention not only has the above excellent physical properties of the molded body, that is, surface roughness Ra, dielectric breakdown voltage, tensile strength and/or tensile elongation, but also has excellent powder physical properties, that is, powder fluidity and / or apparent density. In this specification, the powder fluidity is represented by the fluidity obtained by the following measurement method.

Because the fluidity of the PTFE powder of the present invention can be greater than or equal to, for example, 0.5 times, there is no formation of bridges formed by agglomeration of the powder for molding in the hopper of the molding machine or in the small-diameter cylinder, resulting in uneven filling in the mold or cylinder and other adverse results, thereby improving operability.

The fluidity of the PTFE powder of the present invention may preferably be greater than or equal to 4 times. The fluidity of the PTFE powder of the present invention is measured by the following measurement method, the maximum value of the following measurement method is 8 times, and when the fluidity is within the range, it is usually less than or equal to 8 times, for example, it can be less than or equal to 6 times .

In the present specification, fluidity is a value obtained by a measurement method based on the method described in JP-A-3-259925 and the like. If the fluidity is that of the PTFE powder of the present invention, the PTFE powder of the present invention is used as the powder to be measured in the following measuring method. That is, as the measurement device, upper and lower hoppers 31 and 32 are used, and the hoppers 31 and 32 are supported on a support stand 42 with their center lines aligned as shown in FIG. 1 . The diameter of the inlet 33 of the upper hopper 31 is 74mm, the diameter of the outlet 34 is 12mm, the height from the inlet 33 to the outlet 34 is 123mm, and there is a partition 35 at the outlet 34, through which the powder can be properly held inside or let it flow down. The diameter of the inlet 36 of the lower hopper 32 is 76mm, the diameter of the outlet 37 is 12mm, and the height from the inlet 36 to the outlet 37 is 120mm, and a baffle 38 is provided at the outlet 37 like the upper hopper. Adjust the distance between the upper hopper and the lower hopper so that the distance between the two partitions is 15cm. In addition, 39 and 40 in FIG. 1 are covers for the outlets of the two hoppers, respectively, and 41 is a receiving container for the powder flowing down.

First judge the excellent fluidity of the powder, and calculate the fluidity by the following method according to the judgment result obtained.

Place about 200g of the measured powder in a room with a temperature adjusted to 23.5-24.5°C for no less than 4 hours, pass through a 10-mesh (mesh within 1680 microns) sieve, and then measure the fluidity of the powder at the same temperature .

i) First, use a cup with a volume of 30cc to add exactly 1 cup of the powder to be measured into the upper hopper 31, then immediately pull out the partition 35, and the powder to be measured will fall into the lower hopper. If it cannot fall, use a needle to make it fall . After the powder to be measured falls into the lower hopper 32 completely, place it for 15 ± 2 seconds, pull out the partition plate 38 of the lower hopper, and observe whether the powder to be measured flows from the outlet 37. At this time, the judgment that it can all flow within 8 seconds is fall.

ii) Repeat the same measurement as above three times, and observe whether there is any drop. If the flowability of the powder occurs 2 or 3 times out of the 3 times, it is judged that the powder fluidity is "good", and if it does not fall once, it is judged that the powder flowability is "poor". good". If there is only one drop in the three times, the same measurement is carried out two more times, and the powder fluidity of the measured powder is judged to be "good" in the case of falling in these two times, and the powder fluidity is judged to be "poor" in other cases. good".

iii) For the powder to be measured that is judged to have "good" powder flowability in the above measurement, put 2 cups of powder with the same volume of 30 cc into the upper hopper, and perform the same measurement as above. When the powder flowability is judged to be "good" , increase the number of cups of the powder to be measured in turn, and continue the measurement until it is judged as "bad", up to 8 cups. In each measurement, the powder to be measured that flowed out from the lower hopper in the previous measurement can be reused.

iv) In the above measurement, the more PTFE powder is used, the more difficult it is for the powder to flow. Therefore, the value of the number of cups minus 1 when the fluidity of the powder is "not good" is defined as the "fluidity" of the powder to be measured.

The PTFE powder of the present invention can have an apparent density of, for example, 0.45 g/cm ³ or more, so as in the case of the powder having excellent fluidity, workability can be improved. In addition, as a molding powder, since it can Since the volume per unit weight is reduced, the mold and cylinder of the molding machine can be miniaturized, and the productivity of each mold and cylinder can be improved.

The apparent density of the PTFE powder of the present invention is preferably greater than or equal to 0.5 g/cm ³ , more preferably greater than or equal to 0.6 g/cm ³ , more preferably greater than or equal to 0.7 g/cm ³ , particularly preferably greater than or equal to 0.8 g/cm ³ . When the apparent density of the PTFE powder of the present invention is within the above range, it is usually less than or equal to 1 g/cm ³ , for example, less than or equal to 0.92 g/cm ³ , or even less than or equal to 0.85 g/cm ³ .

The apparent density in this specification is a value measured based on JIS K 6891-5.3.

As described above, the PTFE powder of the present invention is a powdery solid formed of a PTFE-based polymer. As mentioned above, the PTFE-based polymer is formed of modified PTFE and/or non-modified PTFE.

Therefore, the PTFE powder of the present invention can be formed only by non-modified PTFE, also can be formed only by modified PTFE, can also be formed by non-modified PTFE and modified PTFE, in addition In addition to these, a mixture of fillers, additives, and the like may be contained.

In this specification, the "modified PTFE" means a copolymer obtained by copolymerizing monomer components containing tetrafluoroethylene (TFE) and a small amount of other comonomers.

In this specification, the "non-modified PTFE" means a homopolymer of TFE obtained by polymerization, the monomer component of which does not contain the other comonomers.

The other comonomers are not particularly limited as long as they can be copolymerized with TFE, and examples include perfluoroolefins such as hexafluoropropylene (HFP); chlorotrifluoroethylene (CTFE); trifluoroethylene; perfluorovinyl Ether etc.

The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorounsaturated compounds represented by the general formula (1): CF ₂ =CF-ORf. In the general formula (1), Rf represents a perfluoroaliphatic hydrocarbon group. In the present specification, the "perfluoroaliphatic hydrocarbon group" means an aliphatic hydrocarbon group in which all hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms. The perfluoroaliphatic hydrocarbon group may contain oxygen of an ether bond.

Examples of the perfluorovinyl ethers include perfluoro(alkyl vinyl ethers) in which Rf is a perfluoroalkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, as in the general formula (1). (PFAVE).

As the perfluoroalkyl group in the PFAVE, perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, etc. can be mentioned, from creep resistance and From the standpoint of monomer cost, perfluoropropyl is preferable.

Examples of the perfluorovinyl ether include perfluoro(alkoxyalkyl vinyl ethers) in which Rf is a perfluoroalkoxyalkyl group in the general formula (1). In this case, the perfluoroalkoxy group on Rf may be a linear or branched carbon chain, or may have a cyclic ether structure with 1 to 3 oxygen atoms. Such Rf is not particularly limited, and examples include perfluoro(alkoxy) groups with 4 to 9 carbon atoms such as perfluoro(2-methoxypropyl) groups and perfluoro(2-propoxypropyl) groups. an alkyl) group; an organic group represented by the following general formula (2); or an organic group represented by the following general formula (3), etc.

General formula (2):

(In the formula, m represents 0 or an integer of 1 to 4.)

General formula (3):

(In the formula, n represents an integer of 1 to 4.)

In the modified polytetrafluoroethylene, although the types are different, the molar ratio of the tetrafluoroethylene and the other comonomers is preferably the tetrafluoroethylene:the other comonomers=99:2 to 99.999:0.001, more preferably its molar ratio=99:1 to 99.999:0.001. When the content of the other comonomers is less than 0.001 mol%, the creep resistance (total deformation) may decrease, and when the content of the other comonomers exceeds 1 mol%, the tensile strength and the like tend to decrease. In addition, when using In the case of high-valent perfluoro(vinyl ether), the creep resistance cannot be improved corresponding to the content of the other comonomers, which is economically disadvantageous. More preferably, the molar ratio of said tetrafluoroethylene to said other comonomer=99.97:0.03 to 99.8:0.2. Based on the total moles of tetrafluoroethylene and other comonomers, the lower limit of the content of other comonomers is preferably 0.03 mol%, the preferred upper limit is 1 mol%, and the more preferred upper limit is 0.2 mol. %.

As the modified PTFE, one or more different substances such as average molecular weight and copolymer composition can be used. As the non-modified PTFE, one or more substances with different average molecular weights can also be used. substance.

In the PTFE powder of the present invention, the PTFE polymer can be obtained by currently known polymerization methods such as suspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization. From the perspectives commonly used in industry, suspension polymerization and emulsion polymerization are preferably used. Polymerization, more preferably suspension polymerization.

The conditions of the above-mentioned various polymerization methods are not particularly limited. For example, when suspension polymerization is carried out, it is preferably carried out by the following method as disclosed in WO 93/16126.

That is, it is preferable to use a persulfate having a half-life of 18 to 120 hours at 55°C as an initiator, and to perform polymerization at 40 to 55°C. The added amount of the initiator is preferably 4×10 ^-7 to 8×10 ^-6 mol/liter relative to the concentration of the polymerization water so that the decomposition amount of the initiator is 3 hours after the start of the polymerization. If the half-life or decomposition amount of the initiator is within the above range, a high molecular weight PTFE-based polymer can be obtained, for example, excellent tensile strength can be easily obtained, and a polymerization rate suitable for industrial production can be obtained. As a persulfate, ammonium persulfate, potassium persulfate, etc. are mentioned, for example.

In the polymerization, according to different situations, an inert emulsifier such as perfluorocarboxylate, such as ammonium perfluorooctanoate, ammonium perfluorononanoate, etc., can be added in an amount of 1-200 ppm of the polymerization water. In this way, if a small amount of emulsifier is added, the specific surface area of the obtained PTFE powder will increase.

The polymerization time is usually about 8 to 25 hours.

As the PTFE powder of the present invention, if it has the physical properties of a molded body or has the physical properties of a molded body and a powder as described above, it may be the original powder after the polymerization of the PTFE-based polymer, or it may be the original powder after the polymerization. Powder obtained by performing various processes of coarse pulverization, washing, drying, pulverization and/or granulation.

The methods of the coarse pulverization, the washing and the drying are not particularly limited, and for example, conventional methods can be used. For example, when the above-mentioned PTFE-based polymer is polymerized by suspension, the average particle diameter of the raw powder after polymerization is about several millimeters, so it is coarsely pulverized in an aqueous medium, washed in a washing tank, and then dried. In addition, the coarse pulverization in this specification is a process different from the pulverization, and the main difference from the pulverization is that the particle size obtained is relatively large, and generally large particles with an average particle size larger than about 100 μm can be obtained. .

The pulverization is usually carried out after necessary coarse pulverization, washing and drying of the raw powder after polymerization of the PTFE-based polymer. In the present invention, the raw powder after the polymerization of this PTFE polymer has been subjected to necessary coarse crushing, cleaning, and drying without performing the pulverization, granulation or heating to a temperature not lower than the melting point of the PTFE polymer. The processed particles of the temperature are called "PTFE uncrushed powder".

By carrying out the pulverization, the PTFE powder of the present invention can obtain, for example, a powder for molding having the particle diameter of the original powder after the polymerization of the PTFE polymer, and it is not necessary to remove particles that are not in the particle diameter range of the object, which can improve Molded body physical properties and powder physical properties.

The average particle diameter of the particles obtained by the pulverization is not particularly limited. From the viewpoint of obtaining a compact molded product with excellent physical properties and excellent powder physical properties, the average particle diameter of the particles is preferably less than or equal to, for example, 100 μm, a more preferred lower limit is 3 μm, a more preferred upper limit is 60 μm, and the average particle size of the particles is more preferably 3 to 60 μm. Depending on the physical properties of the intended molded article, etc., it can be appropriately selected within the above range.

In the present specification, the average particle diameter after pulverization is a value obtained by the following dry laser method.

That is, the powder to be measured was measured using a HELOS & RODOS system (trade name, manufactured by SYMPATEC Co., Ltd.), and a value corresponding to a cumulative weight percentage of 50 was adopted as the average particle diameter d ₅₀ =X μm of the powder to be measured.

The measurement method is as follows. Put 15-30g of the powder to be measured in the hopper of the system, and use the vibrator attached to the hopper to send the powder to be measured into the dispenser. Then, the dispenser sucks the measured powder at -150 millibar (mbar), and the sucked measured powder is dispersed by compressed air with a dispersion pressure of 1 bar (bar). The dispersed powder to be measured is conveyed to the measurement sensor part of the system, and the image of the powder to be measured reflected by the laser is sensed by the measurement sensor part, so that the system calculates the particle size distribution of the powder to be measured to obtain Get the value of the average particle size d ₅₀ .

The pulverization method is not particularly limited, and for example, various pulverizers such as a hammer mill, a pulverizer having a rotor with paddles, an airflow energy type pulverizer, and an impact pulverizer can be used in the presence of water or in a dry state. However, it is preferable to perform the pulverization in a state where the obtained particles are not substantially fibrous.

For the PTFE powder obtained by pulverization, a small amount of fibrosis may occur on the premise that no substantial fibrosis occurs.

For the granules obtained by the pulverization, for example, when the granules obtained are observed by electron micrographs, no substantial fibrous sheets appear on the surface of the particles and have a smooth curved surface, which means that the granules obtained by the pulverization are not substantially fibrous.

In this specification, the pulverization method capable of substantially preventing the fibrillation of the pellets is referred to as the "fibrillation prevention pulverization method".

As the pulverization method, by using the fibrillation preventing pulverization method, fine pulverization can be performed with no or almost no fibrosis. Therefore, when the obtained PTFE powder is used for molding, the pressure conductivity is excellent when pressurized in the pre-molding, and a dense molded body with excellent physical properties can be obtained, and a powder with excellent physical properties can be obtained. PTFE powder of the present invention.

As the pulverization method for preventing fibrosis, for example, a method that can minimize the shearing force applied during pulverization is preferable. Such a pulverization method for preventing fibrosis is not particularly limited, and examples thereof include an air jet pulverization method, a freeze pulverization method, a refrigerated air jet pulverization method, a water jet pulverization method, and the like. One or more of these pulverization methods may be used in combination.

The air jet pulverization method, freeze pulverization method, refrigerated air jet pulverization method, and water jet pulverization method are the same as those described later for the production method of PTFE molding powder.

As the pulverization method, a freeze pulverization method, a refrigerated air jet pulverization method, and an air pulverization method are preferable, and a refrigerated air jet pulverization method is more preferable.

The granulation is usually carried out after the raw powder after polymerization of the PTFE-based polymer is pulverized. With regard to the PTFE powder of the present invention, by carrying out the granulation, the physical properties of the molded body are not substantially impaired, and the powder physical properties are improved.

Therefore, for the PTFE powder of the present invention, whether to carry out the granulation can be selected according to the application, and the selection range as the powder for molding can be expanded. As described above, it is possible to have excellent molded product physical properties or excellent molded product physical properties and powder physical properties.

As the PTFE powder of the present invention, if the application focuses on the physical properties of the molded body, the granulation may not be performed after the pulverization, and if the application focuses on the physical properties of the powder or in the application, the physical properties of the powder and the molded body should be emphasized. In the case of physical properties, the granulation is performed after the pulverization.

The average particle size of the granules obtained by the granulation is not particularly limited, and is affected by the particle size of the granulated material and granulation conditions, etc., from the point of view of improving the physical properties of the powder without substantially damaging the physical properties of the molded body, The average particle size may be, for example, 30 to 800 μm, with a preferred upper limit of 700 μm. The average particle size is preferably 30 to 700 μm, and can be appropriately selected within the above range according to the physical properties of the desired molded body and powder.

In the present specification, the average particle diameter after the granulation is a value obtained by the method for measuring the average particle diameter of granular powder described in WO98/41569. That is, standard sieves of 10, 20, 32, 48, 60 and 80 meshes are stacked sequentially from the top, PTFE powder is loaded on the 10 mesh sieve, and gradually finer PTFE powder particles are dropped from the vibrating sieve, and the percentage on each sieve is calculated by percentage. The proportion of residual PTFE powder corresponds to the mesh of each sieve (horizontal axis) on the logarithmic probability paper, draws the cumulative percentage of the residual proportion (vertical axis), connects these points with a straight line, and finds that the proportion on the straight line is 50% particles, this value is taken as the average particle diameter.

The granulation method is not particularly limited, but an underwater granulation method is preferred. The water granulation method is not particularly limited. For example, a commonly used method can be used. When stirring in water for granulation, it is preferable to form a liquid-liquid interface with water on an organic liquid and a nonionic and/or anionic surface. The granulation is carried out with stirring in the presence of the active agent. Such a granulation method is disclosed in JP-A-10-259252 and JP-A-10-316763, and is referred to as "emulsification-dispersion-granulation method" in this specification.

If the emulsification dispersion granulation method is adopted as the granulation method, it is considered that the droplet of the organic liquid becomes smaller and presents an approximately spherical shape during granulation, so that the produced PTFE polymer in the droplet The average particle size of the particles also becomes smaller and assumes a nearly spherical shape, which results in an increase in the apparent density and powder flowability of the particles at the same time.

Examples of the organic liquid that forms a liquid-liquid interface with water used in the emulsification dispersion granulation method include alcohols such as 1-butanol; ethers such as diethyl ether; ketones such as methyl ethyl ketone; and aliphatic hydrocarbons such as pentane. ; Aromatic hydrocarbons such as benzene; Dichloromethane, 1,1,1-trichloroethane, 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,3-dichloro- Halogenated hydrocarbons such as 1,1,2,2,3-pentafluoropropane, 1,1-dichloro-2,2,2-trifluoroethane, 1,1-dichloro-1-fluoroethane, etc. Among them, halogenated hydrocarbons are preferred, and chlorinated hydrocarbons and fluorochlorocarbons are more preferred from the viewpoints of incombustibility and meeting the requirements of fluorine regulations.

The organic liquid that forms a liquid-liquid interface with water is preferably added in an amount of 30% to 90% by weight of the granulated powder of the PTFE polymer, the lower limit is preferably 50% by weight, and the upper limit is preferably 80% by weight, the added amount is more preferably 50% by weight to 80% by weight.

Examples of nonionic surfactants used in the emulsification, dispersion and granulation method include amine oxides, polyoxyethylene alkylphenyl ethers, poly(alkylene oxides) having 3 to 4 carbon atoms, Fragmented polyglycols of hydrophobic segments formed of poly(ethylene oxide) units and hydrophilic segments formed of poly(ethylene oxide) units, and the like.

As the anionic surfactant used in the emulsification dispersion granulation method, higher alcohol sulfate ester salts such as sodium lauryl sulfate; Class or fluorine-containing sulfonic acid anionic surfactants, etc.

In the emulsification, dispersion and granulation method, the organic liquid and the nonionic and/or anionic surfactants may be used alone or in combination of two or more.

Classification may be performed as necessary during the pulverization, after the pulverization and/or after the granulation. The classification method is not particularly limited, and for example, a conventionally known method can be used. For example, when the classification is carried out after the granulation, by setting the classification conditions, a granulated product of PTFE powder with a relatively small average particle size can be obtained, or the physical properties of the powder are slightly worse, but the physical properties of the molded body are improved, Alternatively, the surface roughness Ra can be reduced by, for example, 40%, and the tensile elongation can be increased, for example, by 110% to 130%, compared to the value before the classification.

The PTFE powder of the present invention may contain an appropriate amount of fillers such as reinforcing materials and additives as required. These substances may be used alone or in combination.

When the PTFE powder contains fillers, additives, etc., it is usually preferable to mix the fillers, additives, etc. after the pulverization or the granulation from the viewpoint of uniform dispersion in the obtained PTFE powder.

The additives are not particularly limited, and may be those generally used for molding powders of PTFE-based polymers, such as catalysts, supporting materials, colorants, and the like.

The filler is not particularly limited, and metal fibers or metal powders such as glass fiber, graphite powder, bronze powder, gold powder, silver powder, copper powder, stainless steel powder, stainless steel mesh fiber, nickel powder, nickel fiber, etc. can be mentioned; molybdenum disulfide Powder, fluorinated mica powder, coke powder, carbon fiber, boron nitride powder, carbon black and other inorganic fibers or inorganic powders; polyoxybenzoyl polyester and other aromatic heat-resistant resin powders; polyimide powder, four Fluoroethylene/perfluoro(alkyl vinyl ether) copolymer (PFA) powder, organic powder such as polyphenylene sulfite powder, etc.

As the PTFE powder of the present invention, it is not limited if it has the physical properties of the molded body or the physical properties of the molded body and the powder body. The PTFE unpulverized powder which is not modified PTFE and has an amorphous index (AI) of the PTFE-based polymer equal to or greater than 0.25 is subjected to the pulverization. In this specification, the PTFE powder of the present invention obtained by pulverizing the PTFE unpulverized powder in which the PTFE-based polymer is the non-modified PTFE having an AI within the range is referred to as "PTFE Powder (I)".

In infrared absorption, AI is the ratio (A ₇₇₈ /A 2367 ) of absorbance at 778 cm ⁻¹ (A ₇₇₈ ) to absorbance at 2367 _cm ⁻¹ (A ₂₃₆₇ ). The absorbance at 2367cm ^-1 is the double frequency of the stretching vibration of CF ₂ and increases and decreases proportionally to the film thickness of the object to be measured. AI is an index of crystallinity obtained from a calibration curve of absorbance per unit thickness and X-ray diffraction, and the higher the value of AI, the smaller the crystallinity.

The PTFE powder (I) is obtained by pulverizing the PTFE unpulverized powder formed of a PTFE-based polymer with an extremely low crystallinity, so that the surface roughness can be easily obtained by the compression pressure during molding. A molded body with a lower degree Ra, greater tensile strength and tensile elongation than before, and a high dielectric breakdown voltage. AI may be 0.25-0.4, and the lower limit is preferably 0.3, and AI is preferably 0.3-0.4.

AI within the above range can be obtained by, for example, setting the polymerization temperature of the PTFE-based polymer to be relatively low. For example, by setting the polymerization temperature of the PTFE-based polymer to 1 to 40° C., unpulverized PTFE powder having an AI value within the above range can be easily obtained. The preferred lower limit of the polymerization temperature of the PTFE-based polymer is 3°C, and the preferred upper limit is 25°C.

In this specification, AI is a value obtained by a measurement method based on JIS K 0117.

The PTFE powder (I) is a powder formed of the non-modified PTFE. Generally, non-modified PTFE is different from modified PTFE in that it has high crystallinity and low AI. However, regardless of whether the PTFE powder (I) of the present invention is non-modified PTFE, as described above, it has a high AI and the obtained molded product has excellent physical properties of the molded product.

The average particle size of the PTFE powder (I) is not particularly limited, for example, it may be less than or equal to 60 μm. When the average particle diameter is within the above range, a molded article excellent in surface smoothness, tensile strength, tensile elongation and/or high-voltage insulation can be easily obtained. The lower limit of the average particle diameter is preferably 1 μm, and the average particle diameter is preferably 1 to 60 μm.

The average particle diameter of the PTFE powder (I) is preferably equal to or less than 25 μm from the viewpoint of excellent surface smoothness of the resulting molded article. When the average particle diameter is within the above range, the surface roughness Ra can be made lower than before. At this time, the average particle diameter of the powder may be, for example, 3 to 25 μm.

The average particle diameter of the PTFE powder (I) is preferably 20 to 60 μm, especially from the viewpoint that the resulting molded article has excellent tensile strength. When the average particle diameter is within the above range, the tensile strength can be made higher than before. A preferable lower limit is 40 μm, a more preferable lower limit is 45 μm, a preferable upper limit is 60 μm, and a more preferable upper limit is 55 μm. The average particle diameter of the PTFE (I) is more preferably 40 to 60 μm, and more preferably 45 to 55 μm.

The average particle diameter of the PTFE powder (I) is preferably equal to or less than 6 μm from the viewpoint that the obtained molded article has excellent tensile elongation. When the average particle diameter is within the above-mentioned range, the tensile elongation can be made larger than before. The average particle diameter of the powder may be, for example, 1 to 6 μm, with a more preferable lower limit of 3 μm, and a more preferable average particle diameter of 3 to 6 μm.

Therefore, as the average particle diameter of the PTFE powder (I), from the viewpoint that the obtained molded body has excellent tensile strength, it is preferable that the average particle diameter is 20 to 60 μm, and the obtained molded body has excellent From the viewpoint of surface roughness Ra and tensile elongation, the average particle diameter is preferably less than or equal to 6 μm, the more preferred lower limit is 1 μm, the more preferred lower limit is 3 μm, the more preferred average particle diameter is 1 to 6 μm, and more preferably 3 to 3 μm. 6 μm, and the average particle diameter is preferably 20 to 60 μm from the viewpoint that the overall physical properties of the molded article are good.

As the PTFE powder of the present invention, it is preferable that the PTFE-based polymer is the modified PTFE and the PTFE-based polymer has a heat of crystallization of 18 to 25 J/g without the granulation. Unpulverized powder is subjected to the pulverization. In this specification, the PTFE powder of the present invention obtained by pulverizing the PTFE unpulverized powder in which the PTFE-based polymer is the modified PTFE having a heat of crystallization within the above range is referred to as "PTFE". Powder (II)".

As the modified PTFE of the PTFE powder (II), a copolymer obtained by copolymerizing TFE and PFAVE as monomer components is preferable, and perfluoro(propyl vinyl ether) is preferable as PFAVE. The ratio of PFAVE to all monomer components is preferably 0.03% by weight to 0.2% by weight.

The heat of crystallization is an indicator of the molecular weight of the PTFE-based polymer, and the higher the heat of crystallization, the larger the molecular weight of the polymer. The more preferable upper limit of the heat of crystallization is 23.5 J/g, and more preferably 18-23.5 J/g.

For example, in the polymerization reaction of PTFE-based polymers, an initiator whose half-life and decomposition amount are within the above-mentioned range is selected and used, and the heat of crystallization within the above-mentioned range can be obtained by adjusting the polymerization temperature or polymerization time, etc.

The PTFE powder (II) is obtained by pulverizing the PTFE unpulverized powder formed of the modified PTFE having a relatively high molecular weight, so the PTFE-based polymer has both mechanical strength and flexibility. properties, and it is possible to easily obtain a molded product with greater tensile strength and tensile elongation than before and a high dielectric breakdown voltage.

In the present specification, the heat of crystallization is a value measured by the following method. About 3 mg of unsintered PTFE powder was accurately weighed, placed in a dedicated alumina container, and measured with a differential scanning calorimeter (DSC. Trade name: DSC-50, manufactured by Shimadzu Corporation). When measuring, first raise the temperature of the alumina container to 250°C in a nitrogen atmosphere, keep it for a period of time, then raise the temperature to 380°C at a speed of 10°C/min to fully melt the crystals, and then increase the temperature from 380°C at a speed of 10°C/min The temperature was lowered to 250°C, and the heat of crystallization at the crystallization point was measured. As shown in Figure 2, draw a line from the point at 275°C in the obtained DSC chart to the other end of the peak, and calculate the value of the heat of crystallization by the area enclosed between the peak curve and the lead line. Fig. 2 is an example of Embodiment 8.

The average particle diameter of the PTFE powder (II) is not particularly limited, for example, it may be less than or equal to 60 μm, and it is usually set at 1˜25 μm. When the average particle diameter is within the above range, a molded article excellent in tensile strength, tensile elongation and/or high-voltage insulation can be easily obtained.

The average particle diameter of the PTFE powder (II) is preferably equal to or less than 13 μm, especially from the viewpoint that the resulting molded article has excellent tensile strength. When the average particle diameter is within the above range, the tensile strength can be made stronger than before. In this case, the average particle diameter of the powder may be, for example, 1 to 13 μm.

The average particle diameter of the PTFE powder (II) is preferably equal to or less than 6 μm from the viewpoint that the resulting molded article has excellent tensile elongation. When the average particle diameter is within the above-mentioned range, the tensile elongation can be made larger than before. At this time, the average particle diameter of the powder may be, for example, 1 to 6 μm.

As the PTFE powder of the present invention, it is preferred that when the granulation is not performed, the PTFE-based polymer is finely pulverized into the uncrushed powder of the modified PTFE, so that the average particle diameter of the pulverized powder is less than or equal to 100 μm . In this specification, except for the PTFE powder (II), the PTFE-based polymer is the modified PTFE and the average particle diameter obtained by performing the pulverization on the PTFE unpulverized powder is within the range but not carried out. The granulated PTFE powder of the present invention is referred to as "PTFE powder (III)".

As mentioned above, the PTFE powder (III) is a powder formed by using the modified PTFE, the average particle diameter is within the stated range, and preferably no substantial fibrosis occurs. It is a flexible and dense molded body, so it is possible to easily obtain a molded body with higher surface roughness Ra and tensile elongation than before and a high dielectric breakdown voltage.

The average particle size of the PTFE powder (III) is not particularly limited, and may be set to, for example, 1 to 25 μm. When the average particle diameter is within the above range, a molded article excellent in surface smoothness, tensile elongation, and/or high-voltage insulation can be easily obtained.

The average particle diameter of the PTFE powder (III) is preferably 1 to 13 μm, especially from the viewpoint that the resulting molded article has excellent surface smoothness. When the average particle diameter is within the above range, the surface roughness Ra can be made smaller than before. The preferred lower limit is 6 μm, the preferred upper limit is 10 μm, and the average particle size of the powder is more preferably 6 to 10 μm.

The average particle diameter of the PTFE powder (III) is preferably 1 to 13 μm, especially from the viewpoint that the resulting molded article has excellent tensile elongation. When the average particle diameter is within the above-mentioned range, the tensile elongation can be made larger than before. The preferred lower limit is 6 μm, the preferred upper limit is 10 μm, and the average particle size of the powder is more preferably 6 to 10 μm.

As the PTFE powder of the present invention, it is preferable that the granulated material is the PTFE powder (I), the PTFE powder (II) or ) and/or the PTFE powder (III).

In this specification, for the granulated PTFE powder of the present invention, if the granulated substance is the PTFE powder (I), it is called "PTFE powder (I')"; If the object is the PTFE powder (II), it is called "PTFE powder (II')"; if the granulated object is the PTFE powder (III), it is called "PTFE powder (III')".

For the PTFE powder (I'), the PTFE powder (II') and the PTFE powder (III'), the granulated material has excellent physical properties of the molded body as described above, and can be obtained without substantially damaging its excellent physical properties. In the case of a molded product, improve the physical properties of a powder.

The average particle size of the PTFE powder (I'), the PTFE powder (II') and the PTFE powder (III') is not particularly limited, for example, it can be 30-800 μm, and the preferred upper limit is 700 μm, preferably 700 μm or more. The average particle size is 30-700 μm.

For the granulated PTFE powder of the present invention, the average particle diameter of the granulated material is not particularly limited, and it is preferable that the average particle diameter is 1 ~25 μm.

As mentioned above, the PTFE powder of the present invention can have excellent molded body properties, and in particular, the surface roughness Ra, tensile strength and/or tensile elongation can be compared with powdery solids formed from existing PTFE-based polymers. higher. In addition, the PTFE powder of the present invention can also have excellent physical properties of a molded body and, if necessary, excellent physical properties of a powder.

Although the mechanism by which the PTFE powder of the present invention has such an advantageous effect is not clear, it can be considered as follows.

That is, the PTFE powder of the present invention is not particularly limited if it is a powdery solid having the above-mentioned molded body properties or the above-mentioned molded body properties and powder properties. As mentioned above, without the granulation, The PTFE powder excellent in moldings, especially the PTFE (I), the PTFE (II), and the PTFE (III) can give particularly excellent physical properties of moldings.

Therefore, it is considered that the excellent characteristics of the PTFE powder of the present invention come from the non-pulverized PTFE powder formed from non-modified PTFE with AI greater than or equal to 0.25 or modified PTFE with heat of crystallization of 18 to 25 J/g as described above. The pulverization, or the pulverization of the PTFE formed from the modified PTFE makes the average particle size of the powder less than or equal to 100 μm. As the pulverization, in particular, when the fibrillation preventing pulverization method is adopted, substantial fibrosis hardly occurs, and the physical properties of the molded article are easily improved.

In addition, as mentioned above, the powder physical properties of the PTFE powder of the present invention can be improved by the granulation, wherein, the PTFE powder (I), the PTFE powder (II) and/or the PTFE powder (III) ) when the pulverization is carried out, excellent powder physical properties and molded product physical properties can be simultaneously obtained.

The PTFE powder of the present invention has the following specific features.

(1) The PTFE powder of the present invention is characterized in that the surface roughness Ra of the molded body a1 for measurement is less than 0.92 μm. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (1)". When the surface roughness Ra is within the above range, a molded article excellent in surface smoothness can be easily obtained. On the other hand, the conventional PTFE powder cannot obtain the surface roughness Ra within the above range.

As described PTFE powder (1), preferred described PTFE powder (I), described PTFE powder (III) and described PTFE powder (I '), more preferably the described PTFE powder ( I), the PTFE powder (III) with an average particle diameter of 1-13 μm and the PTFE powder (I′) with an average particle diameter of 20-250 μm.

As the PTFE powder (1), it is preferable that the surface roughness Ra of the molded body a1 for measurement is less than 0.8 μm. As such the PTFE powder (1), the PTFE powder (I) having an average particle diameter of 1 to 25 µm and the PTFE powder (I') having an average particle diameter of 20 to 60 µm are preferable.

The PTFE powder (1) is not particularly limited, for example, it can be applied to the molding of molded products requiring small surface roughness such as spherical valve seats, non-cut sealing rings, and large-sized thin plates for semiconductor corner grooves.

(2) The PTFE powder of the present invention is characterized by having an apparent density of 0.45 g/cm ³ or more and a surface roughness Ra of the molded body a1 for measurement of less than 1.9 μm. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (2)". When the apparent density and the surface roughness Ra are within the above ranges, it is possible to reduce the size of the mold and the like, prevent bridging and the like formed in the hopper, and obtain a molded article with excellent surface smoothness easily.

As the PTFE powder (2), the PTFE powder (I') is preferred.

Existing PTFE powders show the correlation that the surface roughness Ra increases with the increase of the apparent density, for example, when the apparent density is within the stated range, the surface roughness Ra is greater than or equal to 1.9 μm, but The PTFE powder (2) has absolutely no notion of this correlation.

The PTFE powder (2) preferably has an apparent density of 0.6 g/cm ³ or more and a surface roughness Ra of the molded body a1 for measurement of less than 1.6 μm.

The PTFE powder (2) preferably has an apparent density of 0.7 g/cm ³ or more and a surface roughness Ra of the molded body a1 for measurement of less than 1.2 μm. As such said PTFE powder (2), the said PTFE powder (I') with an average particle diameter of 80-140 micrometers is preferable.

The PTFE powder (2) is not particularly limited, for example, it can be applied to molded products that require low surface roughness and high apparent density to improve productivity, such as large-sized thin plates used in semiconductors, various corner grooves, slide plates, etc. molding.

(3) The PTFE powder of the present invention is characterized in that its fluidity is 0.5 times or more, and the surface roughness Ra of the molded body a1 for measurement is less than 1.9 μm. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (3)".

When the fluidity and surface roughness Ra are within the above ranges, the powder fluidity is excellent, bridging in the hopper can be prevented, and a molded article with excellent surface smoothness can be obtained. In addition, even if the pressure applied during compression molding is reduced, excellent molded product physical properties can be obtained, so it can also be applied to so-called large molded products.

The PTFE powder (3) preferably has a fluidity of 0.5 or more and a surface roughness Ra of the molded body a1 for measurement of less than 1.6 μm.

As the PTFE powder (3), it is more preferable that the fluidity is greater than or equal to 0.5 times and the surface roughness Ra of the molded body a1 for measurement is less than 1.2 μm. The roughness Ra is less than 1.6 μm, the latter being preferred.

The PTFE powder (3) preferably has a fluidity of 4 or more and a surface roughness Ra of the molded body a1 for measurement of less than 1.2 μm.

As the PTFE powder (3), the PTFE powder (I') is preferred.

The PTFE powder (3) is not particularly limited, for example, it can be applied to the molding of molded products that require low surface roughness and high powder fluidity to improve productivity, such as large-sized thin plates for semiconductor corner grooves.

(4) The PTFE powder of the present invention is characterized by having a fluidity of 0.5 times or more, an apparent density of 0.45 g/cm ^{3 or more} , and a surface roughness Ra of the molded body a1 for measurement of less than 1.9 μm. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (4)". When the fluidity, apparent density, and surface roughness Ra are within the above-mentioned ranges, the powder fluidity is excellent, bridging formed in the hopper can be prevented, and the miniaturization of the mold can be realized, and at the same time, excellent surface smoothness can be obtained. molding body.

As the PTFE powder (4), it is preferable that its fluidity is greater than or equal to 0.5 times, its apparent density is greater than or equal to 0.6 g/cm ³ and the surface roughness Ra of the molded body a1 for measurement is less than 1.6 μm, and its fluidity is preferably greater than or equal to 4 times, the apparent density is greater than or equal to 0.6 g/cm ³ and the surface roughness Ra of the molded body a1 for measurement is less than 1.9 μm, the latter being preferred.

As the PTFE powder (4), it is more preferred that its fluidity is greater than or equal to 0.5 times, its apparent density is greater than or equal to 0.6 g/cm ³ and the surface roughness Ra of the molded body a1 for measurement is less than 1.2 μm, and it is also preferred that its fluidity is greater than or equal to Equal to 4 times, the apparent density is equal to or greater than 0.8 g/cm ³ and the surface roughness Ra of the molded body a1 for measurement is less than 1.6 μm, the latter is preferred.

As the PTFE powder (4), the PTFE powder (I') is preferred.

The PTFE powder (4) is not particularly limited, for example, it can be applied to the molding of molded products that require low surface roughness and high powder fluidity and apparent density to improve productivity, such as large-sized thin plates for semiconductor corner grooves.

(5) The PTFE powder of the present invention is characterized by having an apparent density of 0.45 g/cm ^{3 or more} and a dielectric breakdown voltage of the molded body a2 for measurement of 9.1 kV or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (5)". When the apparent density and dielectric breakdown voltage are within the above ranges, bridges formed in the hopper can be prevented, molds and the like can be miniaturized, and a molded body excellent in dielectric breakdown strength can be obtained.

Existing PTFE powder shows that the dielectric breakdown voltage decreases with the increase of the apparent density. For example, when the apparent density is within the range, the dielectric breakdown voltage is less than 9.1kV, but the PTFE powder (5) has absolutely no concept of this correlation.

As the PTFE powder (5), it is preferred that the apparent density is greater than or equal to 0.45 g/cm ³ and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 12 kV, and it is also preferred that the apparent density is greater than or equal to 0.5 g/cm ³ and the measured The dielectric breakdown voltage of the molded body a2 is greater than or equal to 9.1 kV, and the latter is preferred.

The PTFE powder (5) preferably has an apparent density of 0.6 g/cm ³ or more and a dielectric breakdown voltage of the molded body a2 for measurement of 12 kV or more.

As the PTFE powder (5), the PTFE powder (I'), the PTFE powder (II') and the PTFE powder (III') are preferable.

The PTFE powder (5) is not particularly limited, for example, it can be applied to the molding of molded products that require high dielectric breakdown voltage and high apparent density to improve productivity, such as insulating tapes and insulating nozzles.

(6) The PTFE powder of the present invention is characterized by having a fluidity of 0.5 times or more and a dielectric breakdown voltage of the molded body a2 for measurement of 9.1 kV or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (6)". When the fluidity and the dielectric breakdown voltage are within the above-mentioned ranges, the powder fluidity is excellent, bridging in the hopper can be prevented, and a molded body with a high dielectric breakdown voltage can be obtained.

Existing PTFE powder shows that the dielectric breakdown voltage decreases with the increase of fluidity, for example, when the fluidity is within the range, the dielectric breakdown voltage is less than 9.1kV, but the PTFE powder (6) There is absolutely no notion of this correlation.

The PTFE powder (6) preferably has a fluidity of 0.5 times or more and a dielectric breakdown voltage of the molded body a2 for measurement of 10 kV or more, and is also preferably a fluidity of 4 times or more and a dielectric breakdown voltage of the molded body a2 for measurement. Greater than or equal to 9.1kV, the latter is preferred.

As the PTFE powder (6), it is more preferable that the fluidity is 0.5 times or more and the dielectric breakdown voltage of the molded body a2 for measurement is 12 kV or more, and the fluidity is 4 times or more and the dielectric breakdown voltage of the molded body a2 for measurement is more preferably The voltage is greater than or equal to 10kV, and the latter is particularly preferred as the PTFE powder (6).

As the PTFE powder (6), the PTFE powder (I'), the PTFE powder (II') and the PTFE powder (III') are preferable. The PTFE powder (I') is preferably a powder obtained by granulating the PTFE powder (I) having an average particle diameter of 1 to 13 µm.

The PTFE powder (6) is not particularly limited, for example, it can be applied to the molding of molded products that require high dielectric breakdown voltage and high powder fluidity, such as insulating tapes and insulating nozzles, to improve productivity.

(7) The PTFE powder of the present invention is characterized by having a fluidity of 0.5 times or more, an apparent density of 0.45 g/cm ^{3 or more} , and a dielectric breakdown voltage of the molded body a2 for measurement of 9.1 kV or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (7)". When the fluidity, apparent density, and dielectric breakdown voltage are within the above-mentioned ranges, it is possible to prevent bridging formed in the hopper, to realize miniaturization of molds, etc., and to obtain a molded body excellent in dielectric breakdown strength.

Existing PTFE powder shows that the dielectric breakdown voltage decreases with the increase of fluidity or apparent density, but the PTFE powder (7) is as described as the PTFE powder (5) and the PTFE powder As stated in (6), there is no notion of such correlation at all.

As the PTFE powder (7), it is preferred that its fluidity is greater than or equal to 0.5 times, its apparent density is greater than or equal to 0.45 g/cm ³ and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 10 kV, and it is also preferred that its fluidity is greater than or equal to 4 Second, the apparent density is equal to or greater than 0.45 g/cm ³ and the dielectric breakdown voltage of the molded body a2 for measurement is equal to or greater than 9.1 kV, the latter being preferred.

As the PTFE powder (7), it is more preferred that its fluidity is greater than or equal to 0.5 times, its apparent density is greater than or equal to 0.45g/cm ³ and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 12kV, and it is also preferred that its fluidity is greater than or equal to 4 times, the apparent density is equal to or greater than 0.6 g/cm ³ and the dielectric breakdown voltage of the molded body a2 for measurement is equal to or greater than 9.1 kV, and the latter is particularly preferred as the PTFE powder (7).

As the PTFE powder (7), the PTFE powder (I'), the PTFE powder (II') and the PTFE powder (III') are preferable. The PTFE powder (I') is preferably a powder obtained by granulating the PTFE powder (I) having an average particle diameter of 1 to 13 µm.

The PTFE powder (7) is not particularly limited, for example, it can be applied to the molding of molded products that require high dielectric breakdown voltage and high apparent density and powder fluidity, such as insulating tapes and insulating nozzles, to improve productivity.

(8) The PTFE powder of the present invention is characterized in that the molded body a3 for measurement has a tensile strength of 58.7 MPa or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (8)". When the tensile strength is within the above range, a molded body having excellent mechanical strength even when a tensile force is applied can be obtained. On the other hand, the conventional PTFE powder cannot obtain the tensile strength in the above-mentioned range.

As the PTFE powder (8), preferably the PTFE powder (I) and the PTFE powder (II), more preferably the PTFE powder (I) with an average particle diameter of 40 to 60 μm and an average particle diameter of 1 to 60 μm 13 μm of said PTFE powder (II).

As the PTFE powder (8), it is preferable that the molded article a3 for measurement has a tensile strength of 60 MPa or more.

As the PTFE powder (8), it is more preferable that the molded body for measurement a3 has a tensile strength of 65 MPa or more. As such said PTFE powder (8), the said PTFE powder (II) with an average particle diameter of 1-13 micrometers is preferable.

The PTFE powder (8) is not particularly limited, for example, it can be applied to the molding of molded products requiring high tensile strength, such as sealing rings and ball valve seats.

(9) The PTFE powder of the present invention is characterized in that the tensile elongation of the molded body a3 for measurement is 556% or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (9)". When the tensile elongation is within the above-mentioned range, a molded body can be obtained that exhibits a high elongation rate during stretching and is less likely to be cut off when it is attached to instruments, appliances, etc. or processed. On the other hand, conventional PTFE powders cannot obtain tensile elongation within the above-mentioned range.

As the PTFE powder (9), preferably the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III), more preferably the PTFE powder (I) with an average particle diameter of 1 to 6 μm ), the PTFE powder (II) with an average particle diameter of 1-6 μm, and the PTFE powder (III) with an average particle diameter of 1-13 μm.

As the PTFE powder (9), it is preferable that the molded article a3 for measurement has a degree of tensile elongation of 600% or more. Such PTFE powder (9) is preferably the PTFE powder (II) having an average particle diameter of 1 to 6 μm.

The PTFE powder (9) is not particularly limited, and can be applied, for example, to the molding of molded products that require a large degree of elongation, such as seamless ring-type sealing rings.

(10) The PTFE powder of the present invention is characterized by having an apparent density of 0.45 g/cm ^{3 or more} and a tensile elongation of the molded body a3 for measurement of 431% or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (10)". When the apparent density and tensile elongation are within the above range, it is possible to prevent bridging formed in the hopper and to realize the miniaturization of molds, etc., and at the same time, a high elongation rate can be obtained when stretching, and it can be applied to the instrument. -Molded body that is not easy to be cut off during installation or processing of appliances, etc.

The PTFE powder (10) preferably has an apparent density of 0.6 g/cm ³ or more and a tensile elongation of the molded article a3 for measurement of 450% or more.

The PTFE powder (10) is preferably the PTFE powder (I'), more preferably a powder formed by granulating the PTFE powder (I) having an average particle diameter of 1 to 13 µm.

The PTFE powder (10) is not particularly limited, and it can be applied, for example, to the molding of molded products that require high tensile elongation and high apparent density to improve productivity, such as seamless ring-type sealing rings.

(11) The PTFE powder of the present invention is characterized in that the molded body a1 for measurement has a surface roughness Ra of less than 1.5 μm, and the molded body a3 for measurement has a tensile strength of 47.8 MPa or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (11)". When the surface roughness Ra and the tensile strength are within the above-mentioned ranges, a molded article having excellent surface smoothness and excellent mechanical strength upon application of tensile force can be obtained.

As the PTFE powder (11), the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III) are preferable.

As the PTFE powder (11), it is preferable that the surface roughness Ra of the molded body a1 for measurement is less than 1.2 μm and the tensile strength of the molded body a3 for measurement is greater than or equal to 50 MPa, and the surface roughness of the molded body a1 for measurement is also preferably Ra is less than 1.5 μm, and the tensile strength of the molded article a3 for measurement is 65 MPa or more, and the latter is more preferable than the former.

As the former, the PTFE powder (I) and the PTFE powder (II) are preferred, and the powders having an average particle diameter of 13 to 60 μm are more preferred. As the latter, the PTFE powder (II) is preferred, and the PTFE powder (II) having an average particle diameter of 1 to 13 μm is more preferred.

As the PTFE powder (11), it is more preferable that the surface roughness Ra of the molded body a1 for measurement is less than 1.5 μm and the tensile strength of the molded body a3 for measurement is not less than 65 MPa.

The PTFE powder (11) is not particularly limited, and it can be used, for example, in the molding of molded products that require low surface roughness and high tensile strength, such as spherical valve seats.

(12) The PTFE powder of the present invention is characterized in that the surface roughness Ra of the molded body a1 for measurement is less than 1.2 μm, and the tensile elongation of the molded body a3 for measurement is 423% or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (12)". When the surface roughness Ra and tensile elongation are within the above-mentioned ranges, it is possible to obtain a molding that is excellent in surface smoothness, exhibits a high elongation rate during stretching, and is not easily cut off when it is attached to instruments, appliances, etc. or during processing. body.

As the PTFE powder (12), the PTFE powder (I), the PTFE powder (II), the PTFE powder (III) and the PTFE powder (I') are preferable. The PTFE powder (I') is preferably a powder having an average particle diameter of 20 to 250 µm after granulating the PTFE powder (I) having an average particle diameter of 6 to 13 µm.

The PTFE powder (12) preferably has a surface roughness Ra of the molded body a1 for measurement of less than 0.92 μm and a tensile elongation of the molded body a3 for measurement of 556% or more. As such described PTFE powder (12), preferred described PTFE powder (I) and described PTFE powder (II), more preferably the described PTFE powder (I) that average particle diameter is 1～6 μm and average particle diameter is The PTFE powder (II) of 1-13 μm.

The PTFE powder (12) is not particularly limited, for example, it can be applied to requirements such as a non-cutting seal ring with a large elongation and low surface roughness without cutting when it is installed on instruments-apparatus, etc. The molding of molded products.

(13) The PTFE powder of the present invention is characterized in that its apparent density is equal to or greater than 0.45 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the tensile elongation of the molded body a3 for measurement is equal to or greater than 370%. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (13)". When the apparent density, surface roughness Ra, and tensile elongation are within the above ranges, bridging formed in the hopper can be prevented and miniaturization of molds, etc. can be realized, while excellent surface smoothness, A molded body that exhibits a high elongation rate during stretching and is less likely to be cut off during installation or processing of instruments, appliances, etc.

As the PTFE powder (13), the PTFE powder (I') and the PTFE powder (II') are preferable.

The PTFE powder (13) preferably has an apparent density of 0.45 g/cm ^{3 or more} , a surface roughness Ra of the molded body a1 for measurement of less than 1.9 μm, and a tensile elongation of the molded body a3 for measurement of 400% or more. , it is also preferred that the apparent density is greater than or equal to 0.6 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 370%. Compared with the former, it is preferable the latter. As the former, the PTFE powder (I') is preferable. As the latter, the PTFE powder (I') and the PTFE powder (II') are preferable.

As the PTFE powder (13), it is more preferable that the fluidity is greater than or equal to 4 times, the apparent density is greater than or equal to 0.6 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 1.9 μm, and the molded body for measurement a3 is preferably Tensile elongation is greater than or equal to 400%. As such said PTFE powder (13), the said PTFE powder (I') is preferable.

There is no special limitation for the PTFE powder (13), for example, it can be applied to those that require high apparent density, low surface roughness without cutting and adaptability to instruments-appliances such as non-cut sealing rings in terms of productivity. Molding of molded products with large elongation when mounting, etc.

(14) The PTFE powder of the present invention is characterized in that its fluidity is greater than or equal to 0.5 times, the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 370%. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (14)". When the fluidity, surface roughness Ra, and stretch elongation are within the above ranges, bridging formed in the hopper can be prevented, and at the same time, excellent surface smoothness, high elongation rate during stretching, and A molded body that is not easily cut off during installation or processing of instruments and utensils.

As the PTFE powder (14), the PTFE powder (I') and the PTFE powder (II') are preferable.

As the PTFE powder (14), it is preferred that its fluidity is greater than or equal to 4 times, that the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and that the tensile elongation of the molded body a3 for measurement is greater than or equal to 370%. The fluidity is equal to or greater than 4, the surface roughness Ra of the molded body a1 for measurement is less than 1.9 μm, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 400%. Compared with the former, the latter is preferable. As the former, the PTFE powder (I') and the PTFE powder (II') are preferable. As the latter, the PTFE powder (I') is preferred.

There is no special limitation on the PTFE powder (14), for example, it can be applied to those that require high powder fluidity, low surface roughness without cutting and adaptability to instruments-appliances such as non-cutting sealing rings. Molding of molded products with large elongation when mounting, etc.

(15) The PTFE powder of the present invention is characterized in that its fluidity is equal to or greater than 0.5, its apparent density is greater than or equal to 0.45 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the molded body for measurement is The tensile elongation of a3 is greater than or equal to 370%. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (15)". When the fluidity, apparent density, surface roughness Ra, and tensile elongation are within the above ranges, bridging formed in the hopper can be prevented, and the miniaturization of molds, etc. can be realized, and surface smoothness can be easily obtained. A molded product that is excellent, exhibits a high elongation rate during stretching, and is not easily cut off during installation or processing of instruments, appliances, etc.

As the PTFE powder (15), the PTFE powder (I') and the PTFE powder (II') are preferable.

The PTFE powder (15) preferably has a fluidity of 0.5 times or more, an apparent density of 0.6 g/cm ^{3 or more} , the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the molded body a3 for measurement has a Tensile elongation is not less than 370%, and it is also preferable that the fluidity is not less than 4 times, the apparent density is not less than 0.45g/cm ³ , the surface roughness Ra of the molded body for measurement a1 is less than 2.4 μm, and the molded body for measurement a3 The tensile elongation is greater than or equal to 370%, compared with the former, the latter is preferred.

As the PTFE powder (15), it is more preferable that the fluidity is greater than or equal to 4 times, the apparent density is greater than or equal to 0.6 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.4 μm, and the molded body for measurement a3 The tensile elongation is greater than or equal to 370%.

There is no special limitation for the PTFE powder (15), for example, it can be applied to a non-cut sealing ring that requires high fluidity and apparent density, low surface roughness without cutting, and requires adaptability. Molding of molded products with large elongation at the time of installation, such as instruments and utensils.

(16) The PTFE powder of the present invention is characterized in that the surface roughness Ra of the molded body a1 for measurement is less than 0.92 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is not less than 10 kV. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (16)". When the surface roughness Ra and dielectric breakdown voltage are within the above-mentioned ranges, a molded article having excellent surface smoothness and high dielectric breakdown strength can be easily obtained.

As the PTFE powder (16), preferably the PTFE powder (I) and the PTFE powder (III), more preferably the PTFE powder (I) with an average particle diameter of 1 to 25 μm and an average particle diameter of 1 to 25 μm 13 μm of said PTFE powder (III).

The PTFE powder (16) preferably has a surface roughness Ra of the molded body a1 for measurement of less than 0.8 μm and a dielectric breakdown voltage of the molded body a2 for measurement of 12 kV or more. Such PTFE powder (16) is preferably the PTFE powder (I) having an average particle diameter of 1 to 25 μm.

The PTFE powder (16) is not particularly limited, and it can be used, for example, in the molding of moldings that require low surface roughness and high dielectric breakdown voltage, such as insulating tapes and insulating openings.

(17) The PTFE powder of the present invention is characterized in that its apparent density is equal to or greater than 0.45 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is equal to or greater than 8.5kV. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (17)". When the apparent density, surface roughness Ra, and dielectric breakdown voltage are within the above ranges, bridging formed in the hopper can be prevented and molds can be miniaturized, while excellent surface smoothness and high dielectric breakdown strength can be obtained. molding body.

As the PTFE powder (17), the PTFE powder (I') and the PTFE powder (II') are preferable.

The PTFE powder (17) preferably has an apparent density of 0.6 g/cm ^{3 or more} , a surface roughness Ra of the molded body a1 for measurement of less than 2.5 μm, and a dielectric breakdown voltage of the molded body a2 for measurement of 8.5 kV or more. .

As the PTFE powder (17), it is more preferable that the apparent density is greater than or equal to 0.8 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 8.5 μm. kV. As such said PTFE powder (17), the said PTFE powder (I') is preferable.

The PTFE powder (17) is not particularly limited, and can be used, for example, in the molding of molded products that require high apparent density, low surface roughness, and high dielectric breakdown voltage in terms of productivity, such as insulating tapes and insulating ports.

(18) The PTFE powder of the present invention is characterized in that its fluidity is greater than or equal to 0.5 times, the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 8.5 kV. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (18)". When the fluidity, surface roughness Ra, and dielectric breakdown voltage are within the above ranges, bridging formed in the hopper can be prevented, and a molded body having excellent surface smoothness and high dielectric breakdown strength can be obtained.

As the PTFE powder (18), the PTFE powder (I') and the PTFE powder (II') are preferable.

As the PTFE powder (18), it is preferable that the fluidity is greater than or equal to 0.5 times, the surface roughness Ra of the molded body a1 for measurement is less than 1.9 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 9.1 kV, and it is also preferred that the fluidity is greater than or equal to 0.5 times. degree is greater than or equal to 4 times, the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 8.5 kV, the latter is preferred.

As the PTFE powder (18), it is more preferable that its fluidity is greater than or equal to 4 times, the surface roughness Ra of the molded body a1 for measurement is less than 1.9 μm, and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 9.1 kV, as such The PTFE powder (18), preferably the PTFE powder (I').

The PTFE powder (18) is not particularly limited, and can be applied, for example, to the molding of molded products that require high powder fluidity, low surface roughness, and high dielectric breakdown voltage in terms of productivity, such as insulating tapes and insulating ports.

(19) The PTFE powder of the present invention is characterized in that its fluidity is equal to or greater than 0.5, its apparent density is greater than or equal to 0.45 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the molded body for measurement is The insulation breakdown voltage of a2 is greater than or equal to 8.5kV. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (19)". When the fluidity, apparent density, surface roughness Ra, and dielectric breakdown voltage are within the above ranges, bridging formed in the hopper can be prevented and the miniaturization of molds, etc. can be realized, and at the same time, excellent surface smoothness and A molded body with high dielectric breakdown strength.

As the PTFE powder (19), the PTFE powder (I') and the PTFE powder (II') are preferable.

The PTFE powder (19) preferably has a fluidity of 0.5 times or more, an apparent density of 0.6 g/cm ^{3 or more} , the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the molded body a2 for measurement has a The dielectric breakdown voltage is equal to or greater than 8.5kV, and preferably the fluidity is greater than or equal to 4 times, the apparent density is greater than or equal to 0.45g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.5μm, and the insulation of the molded body a2 for measurement is The breakdown voltage is greater than or equal to 8.5kV, preferably the latter.

As the PTFE powder (19), it is more preferable that its fluidity is greater than or equal to 4 times, its apparent density is greater than or equal to 0.6 g/cm ³ , the surface roughness Ra of the molded body a1 for measurement is less than 2.5 μm, and the molded body for measurement a2 The insulation breakdown voltage is greater than or equal to 8.5kV.

The PTFE powder (19) is not particularly limited, for example, it can be applied to molded products that require high powder fluidity and apparent density, low surface roughness, and high dielectric breakdown voltage in terms of productivity, such as insulating tapes and insulating ports. forming.

(20) The PTFE powder of the present invention is characterized in that the molded body a3 for measurement has a tensile strength of 47.8 MPa or more, and the molded body a3 for measurement has a tensile elongation of 451% or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (20)". When the tensile strength and tensile elongation are within the above ranges, it is possible to obtain excellent mechanical strength even when a tensile force is applied, exhibit a high elongation rate when stretched, and be difficult to install or process to instruments, appliances, etc. Truncated shaped body.

As the PTFE powder (20), the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III) are preferable.

As the PTFE powder (20), it is preferable that the molded body a3 for measurement has a tensile strength of 50 MPa or more, and the molded body a3 for measurement has a tensile elongation of 500% or more. As such said PTFE powder (20), the said PTFE powder (II) is preferable.

As the PTFE powder (20), it is more preferable that the tensile strength of the molded body a3 for measurement is equal to or greater than 65 MPa, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 550%.

There is no special limitation for the PTFE powder (20), for example, it can be applied to such as seamless ring-type sealing rings, etc., which require large tensile elongation and large tensile strength when being adapted to installation of instruments-apparatus, etc. Molding of moldings.

(21) The PTFE powder of the present invention is characterized in that the dielectric breakdown voltage of the molded body a2 for measurement is 11.5 kV or more, and the molded body a3 for measurement has a tensile strength of 47.8 MPa or more. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (21)". When the dielectric breakdown voltage and the tensile strength are within the above ranges, a molded body having a high dielectric breakdown strength and excellent mechanical strength when a tensile force is applied can be obtained.

As the PTFE powder (21), the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III) are preferable.

As the PTFE powder (21), it is preferable that the dielectric breakdown voltage of the molded body a2 for measurement is not less than 12 kV, and the tensile strength of the molded body a3 for measurement is not less than 50 MPa. Such PTFE powder (21) is preferably the PTFE powder (I) and the PTFE powder (II), and the PTFE powder (I) preferably has an average particle diameter of 13 to 60 μm.

As the PTFE powder (21), it is more preferable that the dielectric breakdown voltage of the molded body a2 for measurement is not less than 13 kV, and the tensile strength of the molded body a3 for measurement is not less than 65 MPa. As such said PTFE powder (21), said PTFE powder (II) is preferable.

The PTFE powder (21) is not particularly limited, for example, it can be applied to the molding of molded products with high dielectric breakdown voltage such as insulating tapes and insulating ports, which require high tensile strength suitable for crimping to instruments-apparatus, etc. .

(22) The PTFE powder of the present invention is characterized in that the dielectric breakdown voltage of the molded body a2 for measurement is not less than 10 kV, and the tensile elongation of the molded body a3 for measurement is not less than 556%. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (22)". When the dielectric breakdown voltage and tensile elongation are within the above-mentioned ranges, it is possible to obtain a molded body that has high dielectric breakdown strength, exhibits a high elongation rate when stretched, and is not easily cut off when it is attached to instruments, appliances, etc. or processed. .

As the PTFE powder (22), preferably the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III), more preferably the PTFE powder (I) having an average particle diameter of 1 to 6 μm ), the PTFE powder (II) with an average particle diameter of 1-6 μm, and the PTFE powder (III) with an average particle diameter of 1-13 μm.

As the PTFE powder (22), it is preferable that the dielectric breakdown voltage of the molded body a2 for measurement is not less than 13 kV, and the tensile elongation of the molded body a3 for measurement is not less than 600%. As such said PTFE powder (22), the said PTFE powder (III) with an average particle diameter of 1-13 micrometers is preferable.

The PTFE powder (22) is not particularly limited, for example, it can be applied to molded products with high dielectric breakdown voltage such as insulating tapes and insulating ports, which require a large tensile elongation suitable for installation to instruments-apparatus, etc. molding.

(23) The PTFE powder of the present invention is characterized in that the surface roughness Ra of the molded body a1 for measurement is less than 1.2 μm, the tensile strength of the molded body a3 for measurement is not less than 47.8 MPa, and the tensile elongation of the molded body a3 for measurement is degree greater than or equal to 423%. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (23)". When the surface roughness Ra, tensile strength and tensile elongation are within the above-mentioned ranges, it is possible to obtain a product with excellent surface smoothness, excellent mechanical strength when a tensile force is applied, a high elongation rate when stretched, and an instrument- A molded body that is not easily cut off during installation or processing of appliances, etc.

As the PTFE powder (23), the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III) are preferable.

As the PTFE powder (23), it is preferable that the surface roughness Ra of the molded body a1 for measurement is less than 0.92 μm, the tensile strength of the molded body a3 for measurement is greater than or equal to 47.8 MPa, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 47.8 MPa. Equal to 556%. As such said PTFE powder (23), the said PTFE powder (III) with an average particle diameter of 1-13 micrometers is preferable.

There is no special limitation on the PTFE powder (23), for example, it can be applied to such as seamless ring-type sealing rings, etc. without cutting and requiring low surface roughness, and when it is required to be suitable for installation to instruments-apparatus, etc. Molding of molded products with high tensile strength and large tensile elongation.

(24) The PTFE powder of the present invention is characterized in that the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 10 kV, the tensile strength of the molded body a3 for measurement is greater than or equal to 47.8 MPa, and the tensile elongation of the molded body a3 for measurement is Greater than or equal to 451%. In this specification, the PTFE powder of the present invention having such characteristics is referred to as "PTFE powder (24)". When the dielectric breakdown voltage, tensile strength, and tensile elongation are within the above ranges, it is possible to obtain a high dielectric breakdown voltage, an excellent mechanical strength when a tensile force is applied, a high elongation rate when stretched, and an instrument-appliance. A molded body that is not easily cut off during installation or processing.

As the PTFE powder (24), preferably the PTFE powder (I), the PTFE powder (II) and the PTFE powder (III), more preferably the PTFE powder (I) having an average particle diameter of 6 to 13 μm ), the PTFE powder (II) with an average particle diameter of 1-13 μm, and the PTFE powder (III) with an average particle diameter of 1-13 μm.

As the PTFE powder (24), it is preferable that the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 13kV, the tensile strength of the molded body a3 for measurement is greater than or equal to 47.8MPa, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 451%.

As the PTFE powder (24), it is more preferable that the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 13kV, the tensile strength of the molded body a3 for measurement is greater than or equal to 65MPa, and the tensile elongation of the molded body a3 for measurement is greater than or equal to 500%. As such said PTFE powder (24), the said PTFE powder (II) with an average particle diameter of 6-13 micrometers is preferable.

There is no special limitation for the PTFE powder (24). For example, it can be applied to high insulation breakdown voltages such as insulating tapes and insulating ports, and requires a large tensile strength and a large tensile strength when it is adapted to be installed on instruments-apparatus, etc. Molding of elongated molded products.

As mentioned above, the PTFE powder of the present invention can improve the surface roughness Ra, tensile strength and/or tensile elongation of the molded body compared with the past. PTFE powder of desired apparent density and/or powder flowability.

Therefore, the PTFE powder of the present invention, as described above, can be applied to the molding of various molded articles such as molded articles that require at least one of the above-mentioned physical properties of the molded article, and molded articles that do not want to perform surface smoothing such as chipping. . In addition, even if the pressure applied during compression molding is reduced, excellent physical properties of the molded article can be obtained, so the PTFE powder of the present invention can also be applied to so-called large molded articles.

The molding method using the PTFE powder of the present invention is not particularly limited, for example, a method generally used for powders for forming PTFE-based polymers can be used, and sintering molding methods such as compression molding and press molding are suitable. The molding conditions of various molding methods are not particularly limited, conventionally known methods can be used, and they can be appropriately selected according to the application.

When the PTFE powder of the present invention is used for molding, better powder properties than required can be obtained, so it is possible to prevent bridging formed in the hopper, improve uniform filling into the mold of the molding machine or a small-diameter cylinder, etc. Operability, miniaturization of molds, etc. can be realized, and it can be applied to automatic compression molding machines, etc.

The method for producing PTFE molding powder of the present invention is a method for producing PTFE molding powder.

In this specification, the "PTFE molding powder" is a powdery solid formed of a PTFE-based polymer and used for molding, and means obtained by the method for producing PTFE molding powder of the present invention. As described for the PTFE powder of the present invention, the PTFE-based polymer is formed of modified PTFE and/or non-modified PTFE. The molding is not particularly limited, and compression molding, press molding, isobaric compression molding, and the like are suitably used.

The manufacturing method of the PTFE molding powder of this invention is formed by pulverizing the PTFE unpulverized powder.

The PTFE unpulverized powder is formed of a PTFE-based polymer obtained by suspension polymerization.

As long as it is obtained by suspension polymerization, the PTFE unpulverized powder may be formed only from non-modified PTFE, may also be formed from only modified PTFE, or may be formed from non-modified PTFE and Modified PTFE is formed, and it can also be a mixture with fillers and additives added thereto.

As described for the PTFE powder of the present invention, the "modified PTFE" means a copolymer obtained by copolymerization, which contains tetrafluoroethylene (TFE) as a monomer component and a small amount of other comonomers.

The other comonomers are the same as those mentioned above for the PTFE powder of the present invention.

In the modified polytetrafluoroethylene, although the types are different, the molar ratio of the tetrafluoroethylene and the other comonomers is preferably the tetrafluoroethylene: the other comonomers = 99:1 to 99.999:0.001. When the content of the other comonomers is less than 0.001 mol%, the creep resistance (total deformation) may decrease, and when the content of the other comonomers exceeds 1 mol%, the tensile strength and the like tend to decrease. In addition, when using In the case of high-valent perfluoro(vinyl ether), the creep resistance cannot be improved corresponding to the content of the other comonomers, which is economically disadvantageous. More preferably, the molar ratio of said tetrafluoroethylene to said other comonomer=99.97:0.03 to 99.8:0.2. Based on the total moles of the tetrafluoroethylene and the other comonomers, the lower limit of the other comonomers is preferably 0.03 mol%, and the upper limit is 0.2 mol%.

In the method for producing PTFE molding powder of the present invention, it is preferable that the heat of crystallization of the modified PTFE is 18 to 25 J/g.

As described above, the heat of crystallization is an indicator of the molecular weight of the PTFE-based polymer, and the higher the heat of crystallization, the larger the molecular weight of the polymer. The modified PTFE has a heat of crystallization within the above range and thus has a relatively large molecular weight, and a molded article obtained by molding the PTFE molding powder has the following excellent molded article physical properties. The upper limit of the heat of crystallization is more preferably 23.5 J/g, and the heat of crystallization is more preferably 18-23.5 J/g.

The modified PTFE preferably has a standard specific gravity (SSG) of 2.16 or less. SSG is an indicator of the molecular weight of PTFE-based polymers, and the smaller the SSG, the larger the molecular weight of the polymer. If the SSG is within the above range, the modified PTFE has a relatively large molecular weight, and the molded article obtained by molding the PTFE molding powder has the following excellent molded article physical properties. The lower limit of the SSG is preferably 2.14, and the SSG is preferably 2.14 to 2.16.

In this specification, SSG is measured based on the ASTM D-4894 method. 12 g of the powder to be measured was molded with a cylindrical mold having a diameter of 28.6 mm, and the obtained molded product was baked under the following baking conditions. The baking conditions: set the initial temperature to 290°C, raise the temperature to 360°C at a rate of 120°C/hour, keep at this temperature for 30 minutes, then cool down to 294°C at a rate of 60°C/hour, and keep at this temperature for 24 minute. The obtained fired product was measured with an automatic hydrometer (trade name, manufactured by Shimadzu Corporation).

As the modified PTFE, one or more types of PTFE different in average molecular weight, copolymerization composition, SSG and/or crystallization heat can be used.

In this specification, the same as the non-modified PTFE mentioned for the PTFE powder of the present invention, the "non-modified PTFE" means a homopolymer of TFE obtained by polymerization, which does not contain The other comonomers of the ingredients.

Preferably, the amorphous index (AI) of the non-modified PTFE is greater than or equal to 0.25.

Therefore, as described for the PTFE powder of the present invention, when the non-modified PTFE (homo-PTFE) has an AI within the range, the degree of crystallinity becomes extremely low, and the PTFE molding powder is molded into a The obtained molded article had the following excellent molded article physical properties. The AI may be 0.25-0.4, with a preferred lower limit of 0.3, and the AI is preferably 0.3-0.4.

One or more types of non-modified PTFE having different AI values and/or average molecular weights can be used.

In the method for producing PTFE molding powder of the present invention, the PTFE-based polymer is obtained by suspension polymerization.

The conditions for the suspension polymerization are not particularly limited, and are the same as the suspension polymerization described for the PTFE powder of the present invention, preferably by the method disclosed in WO 93/16126 publication.

In the described modified PTFE polymerization reaction, select the initiator that uses half-life and decomposition amount in the described range, obtain the heat of crystallization in the described range by adjusting polymerization temperature or polymerization time etc., thereby carry out polymerization reaction adjust.

In the non-modified PTFE polymerization reaction, for example, by setting the polymerization temperature of the PTFE-based polymer relatively low, the AI value within the above range can be obtained. The polymerization temperature of the PTFE-based polymer which is easy to obtain the AI value in the range is the same as the polymerization temperature in the description made about the AI of the PTFE powder (I).

In the polymerization, an emulsifier may be added as in the polymerization described for the PTFE powder of the present invention.

The polymerization time is usually 8 to 25 hours.

The PTFE-based polymer obtained by the polymerization can be taken out as a raw powder after polymerization.

The method for producing the powder for molding PTFE of the present invention is to pulverize unpulverized PTFE powder.

In this specification, as described for the PTFE powder of the present invention, the "PTFE unpulverized powder" means that the raw powder after polymerization is subjected to the necessary coarse pulverization, washing and/or drying without performing the pulverization or granulation. powder.

Therefore, as the PTFE unpulverized powder, it may be the original powder of the polymerized PTFE-based polymer, or it may be subjected to the necessary coarse crushing, cleaning and/or drying of the original powder after the polymerization. powder after.

The methods of the coarse pulverization, the washing and the drying are not particularly limited, and conventionally known methods can be used as described for the PTFE powder of the present invention.

The pulverization is characterized in that the particles obtained during the pulverization are not substantially fibrous.

With regard to the PTFE molding powder obtained by pulverization, a small amount of fibrosis may occur on the premise that substantial fibrosis does not occur.

For the particles obtained by the pulverization, as described for the PTFE powder of the present invention, for example, when the obtained particles are observed by electron micrographs, there is no substantial fibrous sheet layer on the surface of the particles and there is a smooth curved surface, which means that no substantial granulation has occurred. fibrosis.

As the pulverization method, a method capable of reducing the shearing force applied during pulverization as much as possible is preferable. Such pulverization method is not particularly limited, and examples thereof include air jet pulverization, freeze pulverization, refrigerated air jet pulverization, and water jet pulverization. One or more of these pulverization methods may be used in combination.

The air jet pulverization method is a method of pulverizing resin particles to be pulverized by jetting compressed air. As the air jet pulverization method, for example, pulverization can be performed using an air jet pulverizer. As such pulverization methods, the methods disclosed in Japanese Patent Application No. 2000-165035 and Japanese Patent Application No. 2000-319668 can be used.

As said air jet milling method, the following methods etc. are mentioned, for example. The pulverized resin particles are continuously supplied from the upper or lower part of the pulverizing chamber of the jet pulverizing device to make the pulverized resin particles flow. collide with each other, and further collide with the inner wall of the bottom side of the pulverization chamber, so as to pulverize, and then collect pulverized resin particles with a desired particle size.

As the nozzle, 3 to 5 nozzles having a diameter of 5 to 10 mm can be used. Air with a flow rate of 3 to 30 cubic meters per minute can be used as the compressed air.

As the inner wall on the bottom side of the pulverization chamber, an inner wall (hereinafter referred to as bottom wall a) that is wholly or partially parallel to the plane of the nozzle, or an inner wall that forms a conical protrusion directly below the injection point ( Hereafter referred to as bottom wall b). As the bottom wall a, it can be in the form that the bottom wall itself is the plane, such as shown in the perspective view of a part of the notch in Figure 3, or it can be the flat top surface that is placed on the bottom wall and is in the shape of a truncated cone. The form of the plane is a frustum as shown in the longitudinal section view of the main part of Figure 4.

The jet milling apparatus is not particularly limited, and examples thereof include jet milling apparatus A shown in FIGS. 3 and 4 . As shown in Figures 3 and 4, the jet milling device A has the following parts: a cylindrical grinding chamber 1; a raw material supply device for the resin particles to be pulverized arranged on the upper part of the pulverizing chamber 1; The upper part of the chamber 1 is used to classify the crushed resin particles after crushing; on the specified position from the bottom wall 3 of the crushing chamber 1 to the middle part 4, the injection point (axis) in the crushing chamber 1 1 point on the center) 3 nozzles 6 arranged opposite to each other; compressed air generating device; gas manifold 7 and piping 8 that supply the generated compressed air to the nozzles 6; powder collector for collecting classified products . A hopper or the like can be used as the raw material supply device, and is connected to the crushing chamber 1 through a supply pipe 9 . As the classification device, a device composed of a classifier wheel 10 and a rotation drive motor can be used. The classifier wheel 10 is connected to the powder collector through a discharge pipe 11 .

In the jet pulverization device A, resin particles to be pulverized are continuously fed in from the upper supply port 13 of the pulverization chamber 1 in the direction of the arrow S, and the resin particles fall into the pulverization chamber 1, and are sprayed from the nozzle 6. The jet stream formed by the compressed air is blown toward the injection point, and the pulverized resin particles formed around the injection point collide with each other to be pulverized. Then, by the action of the jet stream formed from the nozzle 6, most of the pulverized particles colliding with each other and scattered around the jet point collide with the plane of the bottom wall 3 and are further pulverized. At this time, since the nozzle 6 is arranged at a position where the crushing efficiency is high, the crushing effect of the resin particles to be crushed is good, and the amount of particles crushed into fine powder increases. In this way, with the help of the rotating force of the classifier wheel 10 of the classification device arranged on the upper part of the crushing chamber 1, the crushed resin particles are absorbed through the discharge pipe 11 and accumulated in the powder collector to be crushed. collect.

As the form of the bottom wall a, as shown in FIG.

The bottom wall b is different from the flat surface of the bottom wall a in that a conical protrusion is provided. By arranging conical protrusions, the pulverized resin particles collide with each other on the injection points and collide with the surface of the protrusions, and are further pulverized, and at the same time, the air flow in the pulverization chamber is smooth to promote the pulverized resin particles flow, which improves particle impact efficiency and facilitates the collection of crushed resin particles.

The freeze pulverization method is a method of pulverizing resin particles to be pulverized in a frozen state by impact force of a hammer mill or the like. The pulverized resin particles in a frozen state are usually at a temperature of -100°C or lower, for example, preferably -140 to -110°C.

For example, the freeze grinding method can be performed using a freeze grinder. As the freeze-grinding method, for example, by simultaneously supplying low-temperature liquid gas such as liquid nitrogen or the like to the grinder, the resin particles to be pulverized are kept in a frozen state, and the crushed resin particles in the frozen state are crushed by a hammer mill-like impact grinder. A method of pulverizing resin particles to be pulverized, etc.

The refrigerated air jet pulverization method is a method of pulverizing resin particles to be pulverized in a frozen state by spraying compressed air. Similar to the freeze pulverization method, the pulverized resin particles in a frozen state are usually at a temperature of -100°C or lower, for example, preferably -140 to -110°C.

For example, the refrigerated air jet milling method can be performed using the refrigerated air jet milling machine. As the refrigerated air jet pulverization method, for example, by simultaneously supplying a low-temperature liquid gas such as liquid nitrogen to a pulverizer to freeze the resin particles to be pulverized, and then compressing them by jet compression as in the freeze pulverization method, A method in which air pulverizes frozen resin particles to be pulverized, etc.

The water jet pulverization method is a method of pulverizing resin particles to be pulverized by spraying water. For example, the water jet milling method can be performed using a water jet mill. Examples of the water jet pulverization method include a method in which resin particles to be pulverized are pulverized by spraying water through a nozzle in a pulverization chamber of a pulverizer.

As the pulverization method, a freeze pulverization method, a refrigerated air jet pulverization method, and an air jet pulverization method are preferable, and a refrigerated air jet pulverization method is more preferable.

In the method for producing PTFE molding powder according to the present invention, the pulverization is preferably performed so that the average particle diameter of the unpulverized PTFE powder after the pulverization is 100 μm or less. Such small microparticles can be obtained without substantial fibrillation by the pulverization. For example, the average particle size may be 1 to 100 μm, but from the viewpoint of obtaining a compact molded body with excellent physical properties, the preferred lower limit is 3 μm, and the preferred upper limit is 60 μm. Preferably, the average particle size is, for example, 3~60μm. The average particle diameter is adjusted to an appropriate value described below within the above range by adjusting the conditions of the pulverization or the classification according to the physical properties of the intended molded body and the like.

As in the case of the PTFE powder of the present invention, the average particle diameter after pulverization is a value obtained by a dry laser method.

For particles obtained by pulverization in the past, the smaller the particle size, the greater the degree of fibrosis, and it is difficult to finely pulverize without fibrillation. For example, when the average particle diameter after pulverization is 100 μm or less, especially 60 μm or less, such fibrillation is conspicuous. However, as the PTFE molding powder, particles having an average particle diameter of 100 μm or less without substantial fibrosis can be obtained.

The PTFE molding powder can be obtained by the pulverization.

According to different requirements, the PTFE molding powder can be granulated after the crushing.

The average particle diameter of the particles obtained by the granulation is not particularly limited, it is the same as that described for the PTFE powder of the present invention, for example, the average particle diameter of the particles obtained by the granulation can be 30-800 μm, but preferably The upper limit is 700 μm, and the average particle size is preferably 30 to 700 μm, which can be appropriately selected within the above range according to the desired physical properties of the molded article and powder.

In this specification, the measurement method of the average particle diameter after the granulation is the same as the measurement method described for the PTFE powder of the present invention, and the average particle diameter is the average particle diameter of the granular powder described in WO98/41569. The value obtained by the measurement method.

The granulation method is not particularly limited, and for example, conventionally known methods can be used, among which granulation in water is preferred. The underwater granulation method is not particularly limited. For example, it is the same as the granulation method described for the PTFE powder of the present invention, and the emulsification dispersion granulation method is preferable.

As described above, if the emulsification dispersion granulation method is used as the granulation method, it can be considered that the droplets of the organic liquid become smaller and assume a nearly spherical shape during granulation, so the produced in the droplets The average particle size of the PTFE-based polymer particles is also reduced to a nearly spherical shape, and as a result, the apparent density of the particles and the powder fluidity can be improved at the same time.

The surfactant used in the emulsification dispersion granulation method and the emulsification dispersion granulation method is the same as the surfactant described above for PTFE powder.

As in the case of the PTFE powder of the present invention, classification may be performed as necessary during the pulverization, after the pulverization, and/or after the granulation. The classification method is not particularly limited, and for example, a conventionally known method can be used. For example, when the classification is carried out after the granulation, by setting the classification conditions, a granulated product of PTFE powder with a relatively small average particle size can be obtained. The physical properties of the powder are usually slightly worse, but the physical properties of the molded body can be improved. Compared with the value before the classification, for example, the surface roughness Ra can be reduced by 40%, and the tensile elongation can be increased by 110% to 130%.

As in the case of the PTFE powder of the present invention, the PTFE molding powder of the present invention may contain appropriate amounts of fillers such as reinforcing materials, additives, and the like as necessary. One or more of these substances can be used.

When the PTFE molding powder contains fillers, additives, etc., it is usually preferable to mix the fillers, additives, etc. after the pulverization or the granulation from the viewpoint of uniform dispersion in the obtained PTFE molding powder.

The fillers and additives are not particularly limited, and examples thereof include the same fillers and additives as those described for the PTFE powder of the present invention.

For the PTFE molding powder obtained by the manufacturing method of the PTFE molding powder of the present invention, when the powder is made into a molded body, its surface roughness Ra, tensile strength (TS) and/or tensile elongation (EL) is excellent, and its surface roughness Ra, tensile strength, and/or tensile elongation are all improved compared to conventional PTFE powders. In addition, when the PTFE molding powder is formed into a molded body, it can have excellent dielectric breakdown voltage (BDV), and if necessary, can also have excellent surface roughness Ra, tensile strength and/or tensile elongation.

As mentioned above, in this specification, the surface roughness Ra is represented by the measured value of the molded body a1 for measurement, the dielectric breakdown voltage is represented by the measured value of the molded body a2 for measurement, and the tensile strength and/or tensile elongation are represented by The measured value of the molded body a3 for measurement is shown. In the case of the PTFE powder for molding of the present invention, the molded body a1 for measurement, the molded body a2 for measurement, and the molded body a3 for measurement in the measurement methods of the physical properties of each molded body above are obtained by using the PTFE powder for molding as PTFE powder.

The PTFE molding powder of the present invention can make the surface roughness Ra of the molded body a1 for measurement less than 2.5 μm, so the molded body obtained from the PTFE molding powder has a smooth surface as a whole and has few surface irregularities. Therefore, the PTFE molding powder having a surface roughness Ra within the above-mentioned range can be suitably used for molding molded articles such as spherical valve seats that require surface smoothness.

The PTFE molding powder having a surface roughness Ra within the above-mentioned range has excellent surface smoothness, and even when it was previously necessary to smooth the surface by chipping or the like, it is not necessary to perform surface smoothing treatment. Therefore, it is applicable to the molding of molded products that do not include a chipping step in the manufacturing process but require smoothness of the surface, such as molding of non-cutting seal rings and the like.

The PTFE molding powder whose surface roughness Ra is within the above-mentioned range may not require surface smoothing such as chipping. In this case, it is suitable for the field of semiconductor manufacturing where it is required to eliminate contamination of impurities such as chips. Molding of molded products such as appliances and parts. The molded article used in the semiconductor manufacturing field is not particularly limited, and examples thereof include the same molded article as described for the PTFE powder of the present invention.

The surface roughness Ra is preferably less than 1.9 μm, more preferably less than 1.2 μm, and can be adjusted within the range according to different purposes. When the surface roughness Ra is within the above range, it is usually greater than or equal to 0.5 μm, for example, greater than or equal to 0.55 μm.

The surface roughness Ra is more preferably less than 0.92 μm. PTFE powder having such a small surface roughness Ra has not been available conventionally. The PTFE molding powder having a surface roughness Ra of less than 0.92 μm is preferably the following PTFE molding powder (I) and the following PTFE molding powder (III), more preferably having an average particle diameter of 1 to 25 μm. The PTFE molding powder (I) and the PTFE molding powder (III) having an average particle diameter of 1 to 13 μm. Particularly preferably, the surface roughness Ra is less than 0.8 μm.

The powder for molding of PTFE can make the dielectric breakdown voltage of the molded body a2 for measurement equal to or higher than 8.5 kV, so that the molded body obtained from the powder for molding of PTFE can have excellent high-voltage insulation as a whole. Therefore, the PTFE molding powder can be suitably used for molding high-voltage insulating materials such as insulating tapes or insulating gaskets of capacitors for high-voltage transformers, insulating ports for circuit breakers, and the like, for example.

The dielectric breakdown voltage is preferably greater than or equal to 9.1kV, more preferably greater than or equal to 10kV, more preferably greater than or equal to 12kV, particularly preferably greater than or equal to 13kV, and can be adjusted within the range according to different uses. When the dielectric breakdown voltage is within the above range, it is usually less than or equal to 18kV, for example, it may be less than or equal to 15kV, and may even be less than or equal to 14kV.

For the PTFE molding powder, the surface roughness Ra of the molded body a1 for measurement may be less than 0.92 μm, and the dielectric breakdown voltage may be greater than or equal to 10 kV. As such said PTFE molding powder, the following PTFE molding powder (I) and PTFE molding powder (III) are preferred, more preferably the PTFE molding powder (I) and The PTFE molding powder (III) having an average particle diameter of 1 to 13 μm.

Preferably, the PTFE molding powder can make the surface roughness Ra less than 0.8 μm, and the dielectric breakdown voltage be greater than or equal to 12 kV. Such PTFE molding powder is preferably the PTFE molding powder (I) having an average particle diameter of 1 to 25 μm.

The PTFE molding powder can make the tensile strength of the molded body a3 for measurement not less than 47.8 MPa, for example, so when a tensile force is applied, the molded body obtained from the PTFE molding powder has excellent mechanical strength as a whole.

Therefore, the PTFE molding powder can be suitably used for molding of molded articles such as sealing rings and the like that require high strength when stretched due to embedding in devices such as apparatuses and the like. As the seal ring, it is suitable for both a seal ring with a slit that deforms when it is inserted into an appliance, and a ring-like rubber-like seamless ring with no slit on the ring.

In particular, from the standpoint of excellent mechanical strength, the PTFE molding powder is also suitable for molding molded products that generally do not apply tensile force but require high strength, such as spherical valve seats.

The tensile strength is preferably greater than or equal to 50 MPa, and can be adjusted within the range according to different purposes. When the tensile strength is within the above range, it is generally less than or equal to 70 MPa, for example, less than or equal to 66 MPa.

The tensile strength is more preferably greater than or equal to 58.7 MPa. Existing PTFE powders cannot obtain such a large tensile strength. As the PTFE molding powder with the tensile strength greater than or equal to 58.7 MPa, the following PTFE molding powder (I) and PTFE molding powder (II) are preferred, and the ones with an average particle diameter of 40 to 60 μm are more preferred. PTFE molding powder (I) and said PTFE molding powder (II) having an average particle diameter of 1 to 13 μm. The tensile strength is more preferably equal to or greater than 60 MPa.

The tensile strength is particularly preferably greater than or equal to 65 MPa. Such PTFE molding powder is preferably the PTFE molding powder (II) having an average particle diameter of 1 to 13 μm.

The PTFE molding powder can have a tensile strength equal to or greater than 47.8 MPa, and a dielectric breakdown voltage of the molded body a3 for measurement equal to or greater than 11.5 kV. As such a PTFE molding powder, the following PTFE molding powder (I), PTFE molding powder (II) and PTFE molding powder (III) are preferable.

Preferably, the PTFE molding powder can have the tensile strength greater than or equal to 50 MPa and the dielectric breakdown voltage greater than or equal to 12 kV. Such PTFE molding powder is preferably the PTFE molding powder (I) and the PTFE molding powder (II), and the PTFE molding powder (I) preferably has an average particle diameter of 13 to 60 μm. .

More preferably, the PTFE molding powder can have the tensile strength greater than or equal to 65 MPa and the dielectric breakdown voltage greater than or equal to 13 kV. Such PTFE molding powder is preferably the PTFE molding powder (II).

The PTFE molding powder can make the tensile elongation of the molded body a3 for measurement greater than or equal to 370%, so when stretched, the molded body obtained from the PTFE molding powder shows a larger elongation as a whole, It prevents cutting even when tension is applied during installation or processing of instruments and appliances.

Therefore, the PTFE molding powder can be suitably used for molding of molded articles that require a long elongation when embedded in a device or the like, such as molding of seal rings and the like. As the sealing ring, as mentioned in terms of tensile strength, either a sealing ring with a slit on the ring or a seamless ring without a slit on the ring is applicable, but the latter can more fully exert the excellence of the tensile elongation.

The tensile elongation is preferably greater than or equal to 450%, more preferably greater than or equal to 500%, and can be adjusted within the range according to different purposes. When the tensile elongation is within the above range, it is generally less than or equal to 650%, for example, less than or equal to 630%.

The tensile elongation is more preferably equal to or greater than 556%. Existing PTFE powders cannot obtain such a large tensile elongation. As such said PTFE molding powders, the following PTFE molding powders (I), PTFE molding powders (II) and PTFE molding powders (III) are preferred, and those having an average particle diameter of 1 to 6 μm are more preferred. PTFE molding powder (I), the PTFE molding powder (II) with an average particle diameter of 1-6 μm, and the PTFE molding powder (III) with an average particle diameter of 1-13 μm.

The tensile elongation is particularly preferably equal to or greater than 600%. Such PTFE molding powder is preferably the PTFE molding powder (II) having an average particle diameter of 1 to 6 μm.

The PTFE powder for molding can make the tensile elongation greater than or equal to 556%, and the dielectric breakdown voltage of the molded body a2 for measurement is greater than or equal to 10 kV. Such PTFE molding powders are preferably the PTFE molding powder (I), the PTFE molding powder (II) and the PTFE molding powder (III), and more preferably have an average particle diameter of 1 to 6 μm. The PTFE molding powder (I), the PTFE molding powder (II) with an average particle diameter of 1-6 μm, and the PTFE molding powder (III) with an average particle diameter of 1-13 μm.

Preferably, the PTFE molding powder can have the tensile elongation greater than or equal to 600%, and the dielectric breakdown voltage greater than or equal to 13kV. Such PTFE molding powder is preferably the PTFE molding powder (III) having an average particle diameter of 1 to 13 μm.

In the case of granulating the PTFE molding powder, by adjusting the granulation conditions, etc., the excellent physical properties of the molded product can be substantially not damaged, that is, the surface roughness Ra, dielectric breakdown voltage, tensile strength and/or Or tensile elongation, and improve powder properties such as powder fluidity and apparent density.

The PTFE molding powder can make the fluidity greater than or equal to, for example, 0.5 times, so there is no molding powder agglomerating in the hopper of the molding machine or a small-diameter cylinder to form a bridge, resulting in uneven filling in the mold or cylinder Wait for bad results, so improve the operability.

Preferably, the fluidity of the PTFE molding powder is greater than or equal to 4 times. The fluidity of the PTFE molding powder is measured by the above measurement method, and its maximum value is 8 times. When the fluidity is within the above range, it is usually less than or equal to 8 times, for example, it can be less than or equal to 6 times.

As mentioned above, the fluidity in this specification is the value measured by the measuring method based on the method described in Japanese Unexamined-Japanese-Patent No. 3-259925 and the like. Regarding the PTFE molding powder, the PTFE molding powder is used as a powder to be measured in the measurement method.

The PTFE molding powder has an apparent density of, for example, 0.45 g/cm ³ or more, so it can improve workability similarly to the case where the powder has excellent fluidity. In addition, as a molding powder, it can reduce Volume per unit weight, so it is possible to miniaturize the mold and cylinder of the molding machine and increase the productivity of each mold and cylinder.

The apparent density of the PTFE molding powder is preferably greater than or equal to 0.5 g/cm ³ , more preferably greater than or equal to 0.6 g/cm ³ , more preferably greater than or equal to 0.7 g/cm ³ , particularly preferably greater than or equal to 0.8 g/cm ³ . When the apparent density of the PTFE molding powder is within the above range, it is generally less than or equal to 1 g/cm ³ , for example, it may be less than or equal to 0.92 g/cm ³ , or it may be less than or equal to 0.85 g/cm ³ .

As mentioned above, the apparent density in this specification is a value measured based on JIS K 6891-5.3.

In this specification, if the PTFE molding powder is obtained by performing the pulverization on the PTFE unpulverized powder in which the PTFE-based polymer is the non-modified PTFE, and the granulation is not performed, then This is called "PTFE molding powder (I)".

In this specification, if the PTFE molding powder is obtained by performing the pulverization on the PTFE unpulverized powder in which the PTFE-based polymer is the modified PTFE, and the granulation is not performed, it is called This is "PTFE molding powder (II)".

In this specification, if the PTFE-based polymer of the PTFE molding powder is the modified PTFE, the average particle size is less than or equal to 100 μm, the pulverization is not performed, and it is not the PTFE molding powder (II) , it is called "PTFE molding powder (III)".

Therefore, the average particle diameters of the PTFE molding powder (I), the PTFE molding powder (II) and the PTFE molding powder (III) are respectively different from the pulverization of the PTFE unpulverized powder. The average particle size is the same.

The average particle size of the PTFE molding powder (I) is not particularly limited, and may be, for example, 60 μm or less. When the average particle diameter is within the above range, a molded article excellent in surface smoothness, tensile strength, tensile elongation and/or high-voltage insulation can be easily obtained. A preferable lower limit is 1 μm, and the average particle diameter thereof is preferably 1 to 60 μm.

The average particle diameter of the PTFE molding powder (I) is preferably 25 μm or less in view of obtaining a molded article having excellent surface smoothness. When the average particle diameter is within the above range, the surface roughness Ra can be made smaller than before. Such an average particle size may be, for example, 3 to 25 μm.

The average particle diameter of the PTFE molding powder (I) is preferably 25 to 60 μm in view of obtaining a molded product having excellent tensile strength. When the average particle diameter is within the above range, the tensile strength can be made higher than before. A preferable lower limit is 40 μm, a more preferable lower limit is 45 μm, a preferable upper limit is 60 μm, and a more preferable upper limit is 55 μm. The average particle diameter of the PTFE molding powder (I) is more preferably 40 to 60 μm, more preferably 45 to 55 μm.

The average particle diameter of the PTFE molding powder (I) is preferably not more than 6 μm from the viewpoint of obtaining a molded product having excellent tensile elongation. When the average particle diameter is within the above-mentioned range, the tensile elongation can be made larger than before. As such an average particle diameter, it can be 1-6 micrometers, for example, The more preferable lower limit is 3 micrometers, More preferably, the said average particle diameter is 3-6 micrometers.

Therefore, as the average particle diameter of the PTFE molding powder (I), especially from the viewpoint of obtaining a molded body having excellent tensile strength, it is more preferable that the average particle diameter is 25 to 60 μm, and from the viewpoint of excellent surface roughness From the point of view of degree Ra and tensile elongation, the average particle diameter of the PTFE molding powder (I) is preferably less than or equal to 6 μm, a more preferred lower limit is 1 μm, a more preferred lower limit is 3 μm, and the average particle diameter is more preferably 1 to 6 μm, more preferably 3 to 6 μm. The average particle diameter of the PTFE molding powder (I) is preferably 25 to 60 μm from the viewpoint of good overall physical properties of the molded article.

The reason why the PTFE molding powder (I) has excellent molded product physical properties is considered to be as follows. That is, the PTFE molding powder (I) is obtained by performing the pulverization on the PTFE unpulverized powder formed from the non-modified PTFE whose AI value is within the range, so as described above, the non-modified PTFE The crystallization heat of permanent PTFE is extremely low.

Therefore, the pulverized particles themselves hardly undergo substantial fibrosis, and the pulverization can substantially prevent the fibrosis of the particles, so the fibrosis of the pulverized particles is suppressed to a certain extent. Therefore, it is considered that by means of the compression pressure during molding, the PTFE molding powder (I) can easily obtain a molding with a smaller surface roughness Ra, greater tensile strength and tensile elongation than before, and a high dielectric breakdown voltage. body.

Generally, non-modified PTFE is different from modified PTFE in that it has high crystallinity and low AI, but the non-modified PTFE of the present invention has a high AI value as described above, so it can be obtained as described above. The physical properties of the molded body.

The average particle size of the PTFE powder (II) is not particularly limited, and may be, for example, 60 μm or less, usually 1 to 25 μm. When the average particle diameter is within the above range, a molded article excellent in tensile strength, tensile elongation and/or high-voltage insulation can be easily obtained.

The average particle diameter of the PTFE molding powder (II) is preferably not more than 13 μm from the viewpoint of obtaining a molded product having excellent tensile strength. When the average particle diameter is within the above range, the tensile strength can be made stronger than before. At this time, the average particle diameter of the powder may be, for example, 1 to 13 μm.

The average particle diameter of the PTFE molding powder (II) is preferably 6 μm or less from the standpoint of obtaining a molded product having excellent tensile elongation. When the average particle diameter is within the above-mentioned range, the tensile elongation can be made larger than before. At this time, the average particle diameter of the powder may be, for example, 1 to 6 μm.

The reason why the PTFE molding powder (II) has the excellent physical properties of the molded article is considered to be as follows. That is, the PTFE molding powder (II) is obtained by performing the pulverization on the unpulverized PTFE powder formed from the modified PTFE having a heat of crystallization within the above range, so as described above, the modified PTFE has a relatively large molecular weight, and especially has both mechanical strength and flexibility. In addition, the pulverization can substantially prevent the fibrillation of the particles. Therefore, it is considered that the obtained PTFE molding powder (II) can easily obtain greater tensile strength and tensile elongation than before and insulation breakdown due to the mechanical strength and flexibility of the PTFE-based polymer. Formed body with high voltage.

The average particle diameter of the PTFE molding powder (III) is not particularly limited, and may be, for example, 1 to 25 μm. When the average particle diameter is within the above range, a molded article excellent in surface smoothness, tensile elongation and/or high-voltage insulation can be easily obtained.

The average particle diameter of the PTFE molding powder (III) is preferably 1 to 13 μm from the viewpoint of obtaining a molded article having excellent surface smoothness. When the average particle diameter is within the above range, the surface roughness Ra can be made smaller than before. A preferable lower limit is 6 μm, a preferable upper limit is 10 μm, and the average particle size of the powder is preferably 6 to 10 μm.

The average particle diameter of the PTFE molding powder (III) is preferably 1 to 13 μm, especially from the viewpoint of obtaining a molded product having excellent tensile elongation. When the average particle diameter is within the above-mentioned range, the tensile elongation can be made larger than before. The preferred lower limit is 6 μm, the preferred upper limit is 10 μm, and the average particle size of the powder is more preferably 6 to 10 μm.

The reason why the PTFE molding powder (III) has the above-mentioned excellent molded product physical properties is considered to be as follows. That is, the PTFE molding powder (III) is a powder that uses the modified PTFE, has a small average particle diameter within the range, and does not have substantial fibrous particles to form a powder that has flexibility. A compact molded body can easily obtain a molded body with a higher surface roughness Ra and tensile elongation than before and a high dielectric breakdown voltage.

In this specification, for the granulated PTFE molding powder, if the granulated material is the PTFE molding powder (I), it is called "PTFE molding powder (I')". If the granulated matter is the powder (II) for the PTFE molding, it is called "the powder for the PTFE molding (II')"; if the granulated matter is the powder for the PTFE molding (III), it is called the It is "PTFE molding powder (III')".

For the PTFE molding powder (I'), the PTFE molding powder (II') and the PTFE molding powder (III'), the granulated objects have excellent molding properties as described above, and can be used in Improves the physical properties of the powder without substantially compromising the excellent physical properties of the molded product.

The average particle size of the PTFE molding powder (I'), the PTFE molding powder (II') and the PTFE molding powder (III') is not particularly limited, for example, it can be 30-800 μm, preferably The upper limit is 700 μm, and the average particle diameter is preferably 30 to 700 μm.

For the PTFE molding powder through the granulation, the average particle diameter of the granulated material is not particularly limited, and it is preferable that the average particle diameter is 1～25μm.

As described above, since the specific PTFE unpulverized powder is pulverized, substantial fibrosis does not occur, so the method for producing PTFE molding powder according to the present invention can obtain excellent pressure transferability during molding pressurization, and the molded product has The PTFE molding powder is excellent in physical properties of a molded product such as surface roughness Ra, dielectric breakdown voltage, tensile strength and/or tensile elongation. In the method for producing PTFE molding powder according to the present invention, the powder physical properties such as apparent density and/or powder fluidity can be obtained without substantially impairing the physical properties of the molded product by performing the granulation after the pulverization. Also excellent as the PTFE molding powder.

Therefore, as described above, the PTFE molding powder can be suitably used for molding various molded articles such as molded articles that require at least one of the above-mentioned physical properties of the molded article, and molded articles that do not want to perform surface smoothing treatment such as chipping. . In addition, even if the pressure applied during compression molding is reduced, excellent physical properties of the molded article can be obtained, so the PTFE molding powder can also be applied to so-called large-sized molded articles. By improving the powder physical properties of the PTFE molding powder further than desired, the workability during molding can be improved, or the size of the mold and the like can be reduced.

The molding method using the PTFE molding powder is not particularly limited, for example, the same method as described for the PTFE powder.

The PTFE molding powder produced by the method of manufacturing the PTFE molding powder is also one of the present invention.

Description of drawings

Figure 1 is a schematic diagram of a device for regulating fluidity.

FIG. 2 is an explanatory diagram of a method of calculating heat of crystallization from a DSC chart measured by DCS in Example 8. FIG.

Figure 3 is a partially notched perspective view of the jet milling apparatus.

Fig. 4 is a longitudinal sectional view of main parts of the jet milling device.

Detailed ways

The following examples are given to illustrate the present invention in more detail, but the present invention is not limited to these examples.

Production example 1 Production of PTFE unpulverized powder (I)

Add 1,600 liters of deoxygenated pure water to a stainless steel autoclave with an internal volume of 2,000 liters and a stirrer, exhaust the internal air with nitrogen, and exchange it with tetrafluoroethylene, then maintain the internal temperature at 30° C. Tetrafluoroethylene was pressed in until the internal pressure was 4 atmospheres, a polymerization initiator (NH ₄ ) ₂ S ₂ O ₈ was added, and tetrafluoroethylene was polymerized while stirring. The pressure decreased as the polymerization proceeded, so additional tetrafluoroethylene was continuously added to maintain the internal pressure at 4 atmospheres. After 5 hours, the reaction was terminated, unreacted tetrafluoroethylene was recovered, and the contents were taken out. With the TK pipeline type high-speed mixer 2S type machine (trade name, Tokujiki Chemical Industry Co., Ltd.), the raw powder of the PTFE-based polymer having an average particle diameter of 5 to 7 mm as the polymer produced is coarsely pulverized to obtain PTFE unpulverized powder (I) having an average particle diameter of about 900 μm. The amorphous index (AI) of the PTFE-based polymer of the obtained PTFE unpulverized powder (I) was measured by the method described above, and the value was 0.300.

Production example 2 Production of PTFE unpulverized powder (III)

3.3 g of ammonium carbonate was dissolved in 54.8 liters of pure water, and the resulting solution was added to a 170-liter autoclave, and stirred at 110 rpm with an anchor stirrer. After degassing, press tetrafluoroethylene until the gauge pressure is 0.5kgf/cm ² G. This operation is repeated 3 times, and then press perfluoro(propyl vinyl ether) into the reaction system with the help of tetrafluoroethylene. After the temperature of the reaction system was raised to 50°C, tetrafluoroethylene was pressurized until the internal pressure of the reaction system was 8 kgf/cm ² G. Ammonium persulfate was added thereto to initiate polymerization. During polymerization, tetrafluoroethylene was continuously pressed to maintain the internal pressure of the reaction system at 8kgf/cm ² G. When the amount of tetrafluoroethylene consumed was 30% by weight of the aqueous medium, the reaction was terminated and the monomer was released. After cooling to room temperature, the obtained raw powder of the PTFE-based polymer was taken out and coarsely pulverized. This coarse powder was dried to obtain PTFE unpulverized powder (III). The heat of crystallization and standard specific gravity (SSG) of the PTFE-based polymer of the obtained PTFE unmilled powder (III) were measured by the method described above, and the heat of crystallization was 22 J/g, and the SSG was 2.148.

Production example 3 Production of PTFE unpulverized powder (II)

3.3 g of ammonium carbonate was dissolved in 54.8 liters of pure water, and the resulting solution was added to a 170-liter autoclave, and stirred at 110 rpm with an anchor stirrer. After degassing, press tetrafluoroethylene until the gauge pressure is 0.5kgf/cm ² G. This operation is repeated 3 times, and then press perfluoro(propyl vinyl ether) into the reaction system with the help of tetrafluoroethylene. After the temperature of the reaction system was raised to 70°C, tetrafluoroethylene was pressurized until the internal pressure of the reaction system was 8 kgf/cm ² G. Ammonium persulfate was added thereto to initiate polymerization. During polymerization, tetrafluoroethylene was continuously pressed to maintain the internal pressure of the reaction system at 8kgf/cm ² G. When the amount of tetrafluoroethylene consumed reached 22.5% by weight of the aqueous medium, the reaction was terminated and monomers were released. After cooling to room temperature, the obtained raw powder of the PTFE-based polymer was taken out and coarsely pulverized. This coarse powder was dried to obtain PTFE unpulverized powder (II). The heat of crystallization and standard specific gravity (SSG) of the PTFE-based polymer of the obtained PTFE unmilled powder (II) were measured by the method described above, and the heat of crystallization was 30 J/g, and the SSG was 2.170.

Production example 4 Production of PTFE unpulverized powder (I)

Add 1600 liters of deoxygenated pure water to a stainless steel autoclave with an internal volume of 2000 liters and a stirrer, exhaust the internal air with nitrogen, and exchange it with tetrafluoroethylene, then keep the internal temperature at 10 ° C, and inject Tetrafluoroethylene was pressed in until the internal pressure was 6 atmospheres, polymerization initiators (NH ₄ ) ₂ S ₂ O ₈ and Fe ₂ SO ₄ were added, and tetrafluoroethylene was polymerized while stirring. As the polymerization proceeded the pressure decreased, so additional tetrafluoroethylene was continuously added to maintain the internal pressure at 6 atmospheres. After 4 hours, the reaction was terminated, unreacted tetrafluoroethylene was recovered, and the contents were taken out. With the TK pipeline type high-speed mixer 2S type machine (trade name, special machine and chemical industry company make), will be the raw powder of the PTFE polymer of 2～3mm as the average particle diameter of the polymer of generation is carried out coarse pulverization, obtains PTFE unpulverized powder (I) having an average particle diameter of about 400 μm. The amorphous index (AI) of the PTFE-based polymer of the obtained PTFE unpulverized powder (I) was measured by the method described above, and the value was 0.300.

Hereinafter, the "PTFE powder" and "PTFE molding powder" in this specification are referred to as "PTFE pulverized product" when not granulated, and "PTFE granulated product" after granulated.

Examples 1-5 Production of PTFE pulverized product (I) by air jet pulverization method and its evaluation

Using a reverse jet mill (trade name, manufactured by Hosokawa Micron Co., Ltd.), under the conditions shown in Table 1, the PTFE unmilled powder (I) obtained in Production Example 1 was pulverized while generating an air jet. , so that it has an average particle diameter as shown in Table 1, PTFE pulverized products 1 to 5 were obtained. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE products 1 to 5 by the methods described above.

Examples 6-7 Production of PTFE pulverized product (III) by air jet pulverization method and its evaluation

PTFE pulverized products 6 to 7 were obtained in the same manner as in Examples 1 to 5 except that the PTFE non-pulverized powder (III) obtained in Production Example 2 was used instead of the PTFE non-pulverized powder (I). Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE products 6 to 7 by the methods described above.

Examples 8-10 Production of PTFE pulverized product (II) by air jet pulverization method and its evaluation

PTFE pulverized products 8 to 10 were obtained in the same manner as in Examples 1 to 5, except that the PTFE non-pulverized powder (II) obtained in Production Example 3 was used instead of the PTFE non-pulverized powder (I). Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE products 8 to 10 by the methods described above.

Examples 11-15 Production of PTFE pulverized product (I) by air jet pulverization method and its evaluation

With a reverse jet mill (trade name, manufactured by Hosokawa Micron Co., Ltd.), under the conditions shown in Table 1, while generating an air jet, the PTFE unmilled powder (I) obtained in Manufacturing Example 4 was pulverized to obtain The average particle diameters shown in Table 1 were obtained to obtain PTFE pulverized products 11 to 15. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE products 11 to 15 by the methods described above.

Table 1

Nozzle diameter (φ) Air supply volume (m3/min) Graded motor revolutions (rpm) Average particle size after pulverization (μm) Example 1 6.3 7.6 6000 4.8 Example 2 10.0 19.3 6000 8.3 Example 3 5.0 4.7 3500 18.5 Example 4 5.0 4.7 2800 30.3 Example 5 10.0 19.3 600 51.5 Example 6 5.0 4.7 8000 8.1 Example 7 5.0 4.7 3500 18.8 Example 8 5.0 4.7 11500 5.1 Example 9 5.0 4.7 8000 7.9 Example 10 5.0 4.7 3500 19.1 Example 11 6.3 7.6 6000 4.6 Example 12 10.0 19.3 6000 8.0 Example 13 5.0 4.7 3500 18.7 Example 14 5.0 4.7 2800 31.8 Example 15 10.0 19.3 600 49.7

Comparative Example 1 Production and Evaluation of Pulverized PTFE-Based Polymer

With the powder machine AP-44 type machine (trade name, Hosokawa Micron Co., Ltd. system), under the condition that peripheral speed is 75m/hour, power is 36kw, processing speed is 180kg/hour, the PTFE that manufacture example 1 obtains is not pulverized The powder (I) was subjected to dry fine pulverization to obtain a pulverized product of a PTFE-based polymer having an average particle diameter of 54 μm. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE-based polymer by the above-mentioned methods.

Comparative example 2 Production and evaluation of pulverized PTFE-based polymer

Add 1600 liters of deoxygenated pure water to a stainless steel autoclave with an internal volume of 2000 liters and a stirrer, exhaust the internal air with nitrogen, and exchange it with tetrafluoroethylene, then keep the internal temperature at 70 ° C, and inject Tetrafluoroethylene was pressed in until the internal pressure was 4 atmospheres, a polymerization initiator (NH ₄ ) ₂ S ₂ O ₈ was added, and tetrafluoroethylene was polymerized while stirring. The pressure decreased as the polymerization proceeded, so additional tetrafluoroethylene was continuously added to maintain the internal pressure at 4 atmospheres. After 5 hours, the reaction was terminated, unreacted tetrafluoroethylene was recovered, and the contents were taken out. Using a TK pipeline high-speed mixer 2S type machine (trade name, Tokukuki Kagaku Kogyo Co., Ltd.), coarsely pulverize the raw powder of the PTFE-based polymer as the polymer to be produced, and obtain PTFE with an average particle diameter of 1500 μm or less. Uncrushed powder.

This PTFE unpulverized powder was subjected to dry fine pulverization in the same manner as in Comparative Example 1 to obtain a pulverized product of a PTFE-based polymer having an average particle diameter of 50 μm. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE-based polymer by the above-mentioned methods.

Comparative example 3 Production and evaluation of pulverized PTFE-based polymer

Except that the PTFE non-pulverized powder (III) obtained in Production Example 2 was used instead of the PTFE non-crushed powder (I), dry fine pulverization was carried out in the same manner as in Comparative Example 1 to obtain a PTFE-based polymer with an average particle diameter of 40 μm. of crushed matter. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE-based polymer by the above-mentioned methods.

Comparative Example 4 Production and Evaluation of Pulverized PTFE-Based Polymer

Except that the PTFE non-pulverized powder (II) obtained in Production Example 3 was used instead of the PTFE non-crushed powder (I), dry fine pulverization was carried out in the same manner as in Comparative Example 1 to obtain a PTFE-based polymer with an average particle diameter of 42 μm. of crushed matter. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE-based polymer by the above-mentioned methods.

Comparative Examples 5-6 Evaluation of pulverized PTFE-based polymers

Non-granulated products 7J and 7AJ (both trade names, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.), which are pulverized PTFE-based polymers, were measured by the above-mentioned methods, and the physical properties were measured. The results are shown in Table 2.

Comparative Example 7 Production and Evaluation of Pulverized PTFE-Based Polymer

With the powder machine AP-44 type machine (trade name, Hosokawa micron company system), at peripheral speed is 75m/ hour, power is 36kw, under the condition that processing speed is 180kg/ hour, the PTFE that manufacture example 4 obtains is not pulverized The powder (I) was subjected to dry fine pulverization to obtain a pulverized product of a PTFE-based polymer having an average particle diameter of 55 μm. Table 2 shows the results of measuring the physical properties of the obtained pulverized PTFE-based polymer by the above-mentioned methods.

Table 2

As can be seen from Table 2, for each PTFE unpulverized powder after dry fine pulverization, the powder and the existing non-granulated pulverized product of PTFE polymer, compared with Comparative Examples 1 to 7, the air jet pulverization method In Examples 1 to 15 in which each of the PTFE unmilled powders was pulverized, the surface roughness Ra, tensile strength, and/or tensile elongation of each molded body for measurement were excellent, and the physical properties of the molded body were improved compared with the previous ones. improved, and PTFE pulverized products with excellent dielectric breakdown strength can be obtained.

Example 16 Manufacture and Evaluation of PTFE Granules (I')

Add 6-8 liters of ion-exchanged water into a 10-liter granulation tank equipped with conical paddles, and adjust the temperature to 17-25°C. 1500 g of PTFE pulverized material 1 obtained in Example 1 was charged into the granulation tank. Then with the speed rotation of 900rpm conical paddle, add non-ionic surfactant PRONONE#208 (trade name, NOF Corporation system) simultaneously, its structure is as follows:

The addition amount was 250 ppm of the PTFE pulverized product 1, and after 2 to 3 minutes, 1200 g of dichloromethane was added as an organic liquid. Continue to stir at a speed of 900rpm for 3 minutes to mix the organic liquid and the PTFE pulverized product 1, then replace the conical paddle with a dispersing paddle, and rotate at a speed of 2000rpm for 2 minutes to carry out sizing, so that the PTFE pulverized product 1 is moistened by the organic liquid Wet so it starts to grain.

Then, replace the dispersing paddle with a conical paddle, stir at a speed of 900 rpm, and simultaneously raise the temperature to 37-40° C. in 15-20 minutes, maintain the temperature for 30 minutes, and evaporate the organic liquid. After the stirring was stopped, the granulated PTFE and water were separated with a 150-mesh sieve. With box-type hot-air circulation drier at 165～170 DEG C, the PTFE granulation obtained by separation is dried for 12～20 hours, obtains PTFE granulation 1 as PTFE granulation (I').

Table 4 shows the results of measuring the physical properties of the obtained PTFE granules 1 by the above-mentioned methods.

Examples 17-23 Production and Evaluation of PTFE Granules (I')

As shown in Table 3, the pulverized PTFE products 1 to 3 used were the same as in Example 16 except that the addition amount of the nonionic surfactant, the mixing amount of the organic liquid, and the holding time at 37 to 40°C were changed. Production was carried out to obtain PTFE granules 2 to 8 as PTFE granules (I').

Table 4 shows the results of measuring the physical properties of the obtained PTFE granules 2 to 8 by the methods described above. In addition, the addition amount of the nonionic surfactant in Table 3 is the quantity (ppm) with respect to PTFE pulverized material.

Example 24 Manufacture and evaluation of PTFE granules (III')

Using PTFE pulverized material 7, add non-ionic surfactant PRONONE#104 (trade name, manufactured by NOF Corporation), its structure is as follows:

The addition amount is 250ppm of PTFE pulverized product 7, and as shown in Table 3, the mixing amount of the organic liquid and the holding time at 37 to 40°C are changed, except that it is produced in the same manner as in Example 16 to obtain PTFE granules 9 which are PTFE granules (III').

Table 4 shows the results of measuring the physical properties of the obtained PTFE granules 9 by the above methods.

Example 25 Manufacture and evaluation of PTFE granules (II')

Using the PTFE pulverized product 10, the PRONONE #104 (trade name, manufactured by NOF Corporation) was added as a nonionic surfactant in an amount of 250 ppm of the PTFE pulverized product 10, and as shown in Table 3, the organic liquid Except for changing the mixing amount and the holding time at 37 to 40° C., the production was carried out in the same manner as in Example 16 to obtain PTFE granules 10 as PTFE granules (II′).

Table 4 shows the results of measuring the physical properties of the obtained PTFE granules 10 by the above methods.

Examples 26-33 Production and Evaluation of PTFE Granules (I')

Using PTFE pulverized products 11 to 13, as shown in Table 3, the addition amount of nonionic surfactant, the mixing amount of organic liquid, and the maintenance time at 37 to 40°C were changed. Production was carried out in the same manner to obtain PTFE granules 11 to 18 as PTFE granules (I′). Table 4 shows the results of measuring the physical properties of the obtained PTFE granules 11 to 18 by the methods described above. In addition, the addition amount of the nonionic surfactant in Table 3 is the quantity (ppm) with respect to PTFE pulverized material.

table 3

Example 34 Classification and Evaluation of PTFE Granules (I')

The PTFE granules 2 obtained in Example 17 were classified with a 60-mesh standard sieve, and the physical properties of the obtained undersize were measured by the above-mentioned methods. The results are shown in Table 4.

Example 35 Classification and Evaluation of PTFE Granules (I')

The PTFE granulated material 5 obtained in Example 20 was classified with an 80-mesh standard sieve, and the physical properties of the obtained undersize were measured by the above-mentioned methods. The results are shown in Table 4.

Example 36 Classification and Evaluation of PTFE Granules (I')

The PTFE granulated material 8 obtained in Example 23 was classified with an 80-mesh standard sieve, and the physical properties of the obtained undersize were measured by the above-mentioned methods. The results are shown in Table 4.

Example 37 Classification and Evaluation of PTFE Granules (I')

The PTFE granules 2 obtained in Example 27 were classified with a 60-mesh standard sieve, and the physical properties of the obtained undersize were measured by the above-mentioned methods. The results are shown in Table 4.

Example 38 Classification and Evaluation of PTFE Granules (I')

The PTFE granulated material 5 obtained in Example 30 was classified with an 80-mesh standard sieve, and the physical properties of the obtained undersize were measured by the above-mentioned methods. The results are shown in Table 4.

Example 39 Classification and Evaluation of PTFE Granules (I')

The PTFE granulated material 8 obtained in Example 33 was classified with an 80-mesh standard sieve, and the physical properties of the obtained undersize were measured by the above-mentioned methods. The results are shown in Table 4.

Comparative Examples 8-22 Evaluation of granules of PTFE-based polymers

For polyflon (polyflon) TFE molding powder M-31, polyflon TFE molding powder M-32, polyflon TFE molding powder M-33, polyflon TFE molding powder M-391S, polyfluorin TFE molding powder M-391, TFE molding powder M-392, TFE molding powder M-393, new TFE molding powder M-139 (all trade names, Daikin Industrial Co., Ltd.); Aflon (aflon) TFE-G307, Aflon TFE-G320, Aflon TFE-G350, Aflon TFE-G352 (all trade names, manufactured by Asahi Glass Co., Ltd.); Teflon ( Registered trademark)-800J, Teflon (registered trademark)-810J (both trade names, manufactured by Mitsui Dupont Fluorochemical Co.); Hesterflon (Hostaflon) TFM-1600 (made by Hoechst Company), through the Method, its physical properties were measured, and the results are shown in Table 4.

Table 4

As can be seen from Table 4, compared with Comparative Examples 8 to 22, which were granulated products of the PTFE-based polymer before, in Examples 16 to 39 after granulating each of the PTFE pulverized products (I) to (III) , each molded article for measurement has excellent surface roughness Ra, dielectric breakdown strength, tensile strength and/or tensile elongation, and can obtain PTFE granules excellent in apparent density and fluidity. In Examples 21 to 23 and Examples 37 to 39 that were classified after granulation, the apparent density and fluidity were worse than those before classification, while the surface roughness Ra, tensile strength and/or tensile elongation Excellent, especially the surface roughness Ra is significantly reduced.

Example 40 Production of pulverized PTFE by freeze pulverization method (I)

The PTFE unpulverized powder obtained in Production Example 1 was supplied to a freeze pulverizer (trade name, manufactured by IM Material Co., Ltd.) at the same time as liquid nitrogen, and pulverized at a pulverization temperature of -120°C so that the average particle diameter after pulverization was 34.7 μm. The freeze pulverizer is a hammer mill-like impact pulverizer.

Examples 41-42 Production of PTFE pulverized product (II) by freeze pulverization method

Except that the PTFE unmilled powder (II) obtained in Production Example 3 was used instead of the PTFE unmilled powder (I), it was pulverized in the same manner as in Example 40, so that the average particle diameters after pulverization were 28.3 μm and 33.8 μm, respectively. .

Example 43 Production of pulverized PTFE by freeze pulverization method (I)

The PTFE unpulverized powder (I) obtained in Production Example 4 is supplied to a freeze pulverizer (trade name, manufactured by IM Materials Co., Ltd.) simultaneously with liquid nitrogen, and pulverized at a pulverization temperature of -120° C., so that the average particle diameter after pulverization is 34.7 μm. The freeze pulverizer is a hammer mill-like impact pulverizer.

From Examples 40 to 43, it can be seen that fine pulverization can be achieved by pulverizing the pulverized PTFE (I) to (II) by the freeze pulverization method.

Since the PTFE powder of the present invention has the above structure, it is possible to obtain a molded body with improved surface roughness Ra, tensile strength and/or tensile elongation, and excellent dielectric breakdown strength. apparent density and/or powder flowability. Since the manufacturing method of the PTFE molding powder of the present invention has the above structure, it is possible to obtain a powder that can improve the surface roughness Ra, tensile strength and/or tensile elongation of the molded body compared to before, and has excellent dielectric breakdown strength. The PTFE molding powder.

Claims (6)

1. non-modified Teflon powder; It is with amorphous index more than or equal to 0.25 non-modified Teflon not pulverized powder pulverize and the non-modified Teflon powder that obtains; The median size of this non-modified Teflon powder is 1～6 μ m; Wherein, non-modified Teflon not pulverized powder be the former powder after the polymerization or the former powder after the said polymerization implemented the powder after necessary coarse reduction, cleaning and/or exsiccant are handled.

2. the method for manufacture of a polytetrafluoroethylmoulding moulding powder; It has the operation of making polytetrafluoroethylmoulding moulding powder through the not pulverized powder of pulverizing tetrafluoroethylene; Being characterized as of this method of manufacture; The not pulverized powder of said tetrafluoroethylene is to be formed by the polytetrafluoroethyl-ne vinyl polymer that suspension polymerization obtains; It is the former powder after the polymerization or the former powder after the said polymerization is implemented the powder after necessary coarse reduction, cleaning and/or exsiccant are handled; Said polytetrafluoroethyl-ne vinyl polymer is formed by the tetrafluoroethylene of non-modification, and said polytetrafluoroethylmoulding moulding powder manufacturing process is that to make median size be the operation of the polytetrafluorethylepowder powder of 1～6 μ m, and said median size is that the polytetrafluorethylepowder powder of 1～6 μ m is non-modified Teflon powder; Said pulverizing sprays comminuting method through air spray comminuting method, freezing and pulverizing method, frozen air or the jet of water comminuting method carries out, and this pulverizing does not take place at the particle that obtains to carry out under the Fibrotic state of essence.

3. the method for manufacture of polytetrafluoroethylmoulding moulding powder as claimed in claim 2, wherein, the amorphous index of said polytetrafluoroethyl-ne vinyl polymer is more than or equal to 0.25.

4. the method for manufacture of polytetrafluoroethylmoulding moulding powder as claimed in claim 2, wherein, said pulverizing is carried out through the air spray comminuting method.

5. the method for manufacture of polytetrafluoroethylmoulding moulding powder as claimed in claim 2, wherein, said pulverizing is carried out through the freezing and pulverizing method.

6. the method for manufacture of polytetrafluoroethylmoulding moulding powder as claimed in claim 2, wherein, said pulverizing is sprayed comminuting method through frozen air and is carried out.

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