JP2002266219A - Tetrafluoroethylene-based nonwoven fabric - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Ultrafine fiber non-woven fabric useful as a filter, heat insulating material, moisture permeable waterproof material, flame retardant material, especially excellent in chemical resistance, flame retardancy, water repellency, mold release, and stain resistance And a microfiber nonwoven fabric and a laminated fiber material particularly useful as a nonwoven fabric filter, a heat insulating material, a moisture permeable waterproof material, and a flameproof material made of a tetrafluoroethylene copolymer. SOLUTION: This is a nonwoven fabric made of a tetrafluoroethylene-based copolymer in which fibers having an average fiber diameter of 0.5 to 10 µm are fused to each other, and the basis weight of the nonwoven fabric is 10 to 2
Non-woven fabric having a weight of 00 g / m ² .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microfiber nonwoven fabric particularly useful as a filter, a heat insulating material, a moisture-permeable waterproof material, and a flameproof material.

More specifically, the present invention relates to a nonwoven fabric made of a tetrafluoroethylene (TFE) copolymer, which is excellent in chemical resistance, flame retardancy, water repellency, mold release properties, and stain resistance.

[0003]

2. Description of the Related Art Conventionally, nonwoven fabrics, woven fabrics, and the like have been used as fiber materials suitable for filters.

As means for obtaining ultrafine fibers having a fiber diameter of 7 μm or less, a melt blow method, composite spinning, electrostatic spinning, and the like are known. Generally, general-purpose materials such as polypropylene, polyester, and polyamide have been mainly used as polymers for obtaining these. In particular, many nonwoven fabrics manufactured by the melt blow method are polyolefin-based, and have a problem that the use temperature is low because of their low melting points.

[0005] Polyesters and polyamides have drawbacks in terms of chemical resistance and water repellency.

On the other hand, fluororesins are excellent in heat resistance, chemical resistance, non-adhesiveness and cleanliness. It is desired to be used as a material for filter bugs and the like. As a method of obtaining a nonwoven fabric made of ultrafine fibers having a fiber diameter of ≦ 10 μ using a fluororesin, a polytetrafluoroethylene (PTFE), which is a homopolymer of TFE, is stretched, cut into fibers, and then subjected to a water jet method or a needle punch method. There is a method of forming a nonwoven fabric, but the fibers are not fused to each other and the strength is insufficient. On the other hand, similarly to polyolefins, polyesters and polyamides usually used as nonwoven fabric fiber materials, when obtaining a molded nonwoven fabric of a thermoplastic fluororesin by a melt blow method or the like, it is difficult to make ultrafine fibers. There is a problem that the strength of the obtained nonwoven fabric is inferior. This is because conventional fluoroplastics generally have a higher polymer melt viscosity, melting point, and crystallization temperature than the above-mentioned general-purpose thermoplastic resins, etc., and solidify faster from the molten state. Can not give enough,
As a result, ultrafine fibers are hardly obtained, and it is considered that fusion between the fibers is insufficient.

Further, JP-A-7-229048 and JP-A-8-92661 disclose that a nonwoven fabric is produced by a melt blow method using an ethylene-chlorotrifluoroethylene copolymer. However, since the fluorine content of the ethylene-chlorotrifluoroethylene copolymer is at most 48% by weight, the obtained nonwoven fabric is not sufficiently satisfactory in chemical resistance, water repellency, antifouling property, release property and the like. Did not.

[0008] As described above, fluororesins have superior characteristics to general-purpose resins, but are sometimes inferior in mechanical strength and are expensive. Therefore, a composite fiber in which the excellent characteristics of the fluororesin are inclined to the fiber surface by melting and mixing these general-purpose resin and the fluororesin is desired.

However, conventional fluororesins have a high melting point,
Melt mixing with the general-purpose resin has been difficult because the melt viscosity at the molding temperature of these general-purpose resins is significantly different from that of the fluororesin.

When the molding temperature is adjusted to that of the fluororesin, the above-mentioned general-purpose resin is thermally decomposed.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides chemical resistance, flame retardancy, water repellency, stain resistance,
An object of the present invention is to provide a nonwoven fabric having excellent releasability.

Further, the present invention relates to an ultrafine TF of submicron to several micron order manufactured by a melt blow method.
An object of the present invention is to provide a nonwoven fabric made of E-based copolymer fibers.

[0013]

That is, the present invention provides a TF
The average fiber diameter of the E-based copolymer is 0.5 to 10 μm
Fibers are fused to each other, and the basis weight is 100 g / m.^TwoThis
Non-woven fabric with a vertical strength of 3.7kg / 5cm or more
And the basis weight of the nonwoven fabric is 10 to 300 g / m ^TwoIs
Related to nonwoven fabric.

The strength in the vertical direction (the vertical direction refers to the winding direction of the nonwoven fabric) per unit weight of 100 gm ² of the nonwoven fabric refers to a sample 10 of 5 cm width × 20 cm length.
About the sheet, Tensilon (A & D Co., Ltd.)
The average value of the maximum strength obtained when the tensile strength was measured at 23 ° C. at a speed of 10 cm / min was converted to a basis weight of 100 g / m ² .

The present invention also relates to a non-woven fabric using a raw material obtained by previously melting and mixing a TFE copolymer and a fluorine-free thermoplastic resin, wherein the average fiber diameter is 0.5 to 10 μm.
Fibers are fused to each other, and the basis weight of the nonwoven fabric is 10 to 10.
It also relates to a nonwoven which is 300 g / m ² .

The nonwoven fabric of the present invention is preferably a nonwoven fabric produced by a melt blow method.

The TFE copolymer used in the present invention preferably has a fluorine content of 55 to 76% by weight.

The TFE-based copolymer includes (A)
TFE and formula (I): CF ₂ ＝ CF—Rf ¹ (I) (wherein, Rf ¹ is CF ₃ or ORf ² (Rf ² is carbon number 1 to 1)
A copolymer with at least one selected from perfluoroolefins represented by 5)
(B) a copolymer of TFE, ethylene and an ethylenic monomer copolymerizable therewith, wherein the copolymerizable ethylenic monomer is hexafluoropropylene (HF
P), chlorotrifluoroethylene (CTFE), formula (I
I): CH ₂ ＣCX ¹ (CF ₂ ) nX ² (II) (where X ¹ is H or F; X ² is H, F or Cl; n)
Is an integer of 1 to 10), represented by the formula (III): CF ₂ ＣＦCF—ORf ² (III) (where Rf ² is a perfluoroalkyl group having 1 to 5 carbon atoms) A copolymer of at least one selected from the group consisting of perfluorovinyl ether and propylene, (C) a copolymer of TFE and vinylidene fluoride (VdF), or (D) a copolymer of TFE and VdF with HFP or CTFE. Is preferred.

From another viewpoint, the melting point of the TFE copolymer is preferably from 120 to 270 ° C, more preferably from 150 to 250 ° C.

From a further viewpoint, the nonwoven fabric of the present invention has a melt viscosity (hereinafter the same) of 1 to 100 P immediately after being discharged from a nozzle of an extruder using a TFE-based copolymer.
What is obtained by being molded in a state in the range of a · sec is preferable.

From another viewpoint of the thermal properties of the TFE copolymer, the TFE copolymer has a melting endothermic peak ΔH
It is preferable to have a thermal property that satisfies the relationship of ending temperature of-end temperature of melting endothermic peak ΔH ≧ 50 ° C.

The present invention also relates to a laminated fiber material in which the nonwoven fabric of the present invention and a nonwoven fabric other than the nonwoven fabric, a woven fabric, a film and / or a sheet are laminated.

The average fiber diameter in the present specification is:
An enlarged photograph (magnification: 1) of a nonwoven fabric taken with a scanning electron microscope.
The fiber diameters of 200 to 200 or more fibers were measured and arithmetically averaged.

[0024]

DETAILED DESCRIPTION OF THE INVENTION TFE constituting the nonwoven fabric of the present invention
The average fiber diameter of the fibers of the system copolymer is 0.5 to 10 μm, preferably 0.5 to 7 μm, and more preferably 1 to 6 μm. Fibers having an average fiber diameter of more than 10 μm are not preferred because the filter characteristics and the like are remarkably reduced and the texture is increased. In the case of fibers having a size of less than 0.5 μm, the strength of the nonwoven fabric is undesirably reduced.

Although there are several methods for producing fibers having an average fiber diameter of 10 μm or less, methods which can be suitably employed in the present invention include a melt blow method, a spun bond method, and a flash spinning method. Among these, the melt blow method is preferred because ultrafine fibers of 10 μm or less can be obtained stably.

The melt blow method is a method in which spinning and production of a nonwoven fabric are performed in a series of steps as follows. First, a thermoplastic resin is supplied to an extruder, for example, a screw type extruder, and melted. The melted resin is discharged from a fine hole (orifice) of a die of a melt flow device. At this time, the discharged molten resin is spun into ultrafine fibers by discharging with heated air. The obtained ultrafine fibers are in the form of a collecting net, and the fibers are bonded to each other by mechanical, thermal or chemical means, processed into a nonwoven fabric form, and continuously wound. Normally, a calendering process is performed in the winding process. However, when the present invention is applied, a calendering process, a needning process, an embossing process may or may not be performed. These may be used in combination.
When performing the calendering process, set the heating temperature to about 50 to 2
It is desirable to have a temperature of 00C, preferably 70-100C, and a minimum pressure (generally about 10-100 psi).

The melt blow method has been conventionally used for the production of spun nonwoven fabrics of general-purpose thermoplastic resins such as non-fluorinated polyolefins (particularly polypropylene), polyamides and polyesters.

In order to obtain a nonwoven fabric of ultrafine fibers of 10 μm or less by the melt blow method, it is desirable to set the orifice diameter of the nozzle of the extruder to 0.5 mm or less.

The basis weight of the nonwoven fabric of the present invention is 10 to 30.
0 g / m ² , preferably 30 to 200 g / m ² ,
More preferably, it is 30 to 100 g / m ² . When the basis weight is less than 10 g / m ² , there is no strength as a nonwoven fabric,
Also, the filter and the waterproof effect are reduced. 300g /
such as clogging of more than m ² is likely to occur, it will be inferior to the filter performance.

The TFE copolymer used in the present invention preferably has a fluorine content of 55 to 76% by weight.
It is more preferably at least 63% by weight. With a TFE-based copolymer having a fluorine content of less than 55% by weight, the resulting nonwoven fabric is inferior in chemical resistance, water repellency, mold release properties, antifouling properties and flame retardancy.

As described above, the TFE-based copolymer includes (A) a copolymer of TFE and at least one member selected from perfluoroolefins of the formula (I),
FE, a copolymer of ethylene and an ethylenic monomer copolymerizable therewith, wherein the copolymerizable ethylenic monomer is hexafluoropropylene, chlorotrifluoroethylene, a fluorocarbon of the formula (II) Olefin, formula (III)
A copolymer of at least one selected from the group consisting of perfluorovinyl ether and propylene,
(C) a copolymer of TFE and VdF, or (D) TF
It is preferably a copolymer of E, VdF and HFP or CTFE.

Specific examples of the TFE-based copolymer (A) include, for example, the following copolymers, but are not limited thereto. (A-1) TFE / perfluoromethyl vinyl ether (PMVE) copolymer. The preferred copolymer composition range is T
FE unit is 80 to 95 mol%, PMVE unit is 5 to 20
Mol%, more preferably 85-92 TFE units.
Mol%, and the PMVE unit is 8 to 15 mol%. (A-2) TFE / HFP copolymer. A preferable copolymer composition range is 80 to 93 mol% of TFE units and 7 to 20 mol% of HFP units, and more preferably 85 to 90 mol% of TFE units and 10 to 15 mol% of HFP units. (A-3) TFE / HFP / perfluoro (alkyl vinyl ether) (PAVE) copolymer. Preferred copolymer composition ranges are 80 to 93 mol% of TFE units, 2 to 20 mol% of HFP units, and 0.5 to 15 mol% of PAVE units.
Is. As PAVE, besides PMVE, perfluoro (ethyl vinyl ether), perfluoro (n-
Propyl vinyl ether).

Specific examples of the TFE copolymer (B)
Are exemplified by the following copolymers, but are not limited thereto
Not something. (B-1) TFE / ethylene / CH_Two= CX^Three(CF_Two)_nX
^Four(X^ThreeIs H or F; X ^FourIs H or F; n is 1 to 10
Integer) copolymer. The preferred copolymer composition range is TFE
The unit is 50 to 75 mol%, and the ethylene unit is 25 to 50 mol%.
%, CH_Two= CX^Three(CF_Two)_nX^FourUnit is 0.5 to 10
Mol%, more preferably 60 to 75 TFE units.
Mole%, 25 to 40 mole% of ethylene units, CH_Two= C
X^Three(CF_Two)_nX^FourThe unit is 0.5 to 5 mol%. CH
_Two= CX^Three(CF_Two)_nX^FourAs CH_Two= CF (C
F_Two)_mH (m is an integer of 1 to 5, particularly preferably 2 to 4
Integer), CH_Two= CH (CF_Two)_mCF_Three(M is an integer of 1 to 5
Number, particularly preferably an integer of 2 to 4).
You. (B-2) TFE / ethylene / HFP copolymer. preferable
The copolymer composition range was such that the TFE unit was 35 to 70 mol%,
25 to 60 mol% of the ethylene unit and 0.1 to the HFP unit
20 mol%, more preferably 40 to 40% of TFE units.
67 mol%, 28 to 45 mol% of ethylene units, HFP
The unit is 1 to 20 mol%. (B-3) TFE / ethylene / HFP / CH_Two= CX^Three(C
F_Two)_nX^Four(X^Three, X^FourAnd n are the same as described above)
body. A preferable copolymer composition range is such that the TFE unit is 35 to 7
0 mol%, 25-60 mol% of ethylene units, HFP unit
0.1 to 20 mol%, CH_Two= CX^Three(CF_Two)_nX^Four
The unit is 0.1 to 5 mol%, more preferably TFE
The unit is 40 to 70 mol%, and the ethylene unit is 30 to 45 mol%.
%, HFP unit is 1 to 18 mol%, CH_Two= CX^Three(C
F_Two)_nX^FourThe unit is 0.5 to 5 mol%.

TFE copolymer (C), that is, TFE
As a specific example of the / VdF copolymer, the TFE unit is 10
６０60 mol%, a copolymer having VdF units of 40-90 mol%, more preferably 30-60 mol% of TFE units, V
It is a copolymer having 40 to 70 mol% of dF units.

The copolymer (D), ie, TFE / VdF /
Specific examples of the HFP or CTFE copolymer include TF
E unit is 10 to 60 mol%, VdF unit is 40 to 90 mol%, HFP or CTFE unit is 0.5 to 20 mol%.
And more preferably 30 to 60 mol% of TFE units, 40 to 70 mol% of VdF units, HFP and / or
Alternatively, it is a copolymer having a total of 0.5 to 15 mol% of CTFE units.

The copolymers (A) and (B) have high chemical resistance among the TFE-based copolymers used in the present invention, so that they are suitable for applications requiring chemical resistance.

The TFE copolymer used in the present invention can be produced by a conventionally known polymerization method. For example, industrially, a fluorine-based solvent is used, an organic peroxide is used as a polymerization initiator, suspension polymerization is performed in an aqueous medium, or a fluorine-based surfactant is used, and ammonium persulfate or peroxide is used as a polymerization initiator. Aqueous emulsion polymerization using a persulfate represented by potassium sulfate is preferred, but not limited thereto. In the case of suspension polymerization, hydrochloroalkanes, hydrofluoroalkanes, perfluoroalkanes, and the like are advantageously employed as the fluorine-based solvent. The amount of the solvent used should be 10 to 100% by weight based on the water suspension.
It is preferable in terms of economy.

The polymerization temperature is not particularly limited,
Industrially, the temperature may be 0 to 100 ° C. The polymerization pressure is usually 0 to
The pressure may be 10 MPaG, but it is appropriately determined according to the type and amount of the solvent used and other polymerization conditions such as vapor pressure and polymerization temperature.

In the production of the TFE copolymer of the present invention, a conventional chain transfer agent such as isopentane, n-pentane, n-hexane, cyclohexane, methanol, ethanol, carbon tetrachloride, chloroform, etc. Methylene chloride, methyl chloride and the like may be used.

The TFE copolymer used in the present invention is a copolymer which can be melt-processed and has a melting point of 120 to 270 ° C.
Particularly, those having a temperature in the range of 150 to 250 ° C. are preferable because they are excellent in melt processability, particularly in spinning processability by a melt blow method, and are excellent in mutual heat fusion of fibers.

From the viewpoint of spinning and processing by the melt blow method, the TFE-based copolymer has an end temperature of the melting endothermic peak ΔH−a starting temperature of the melting endothermic peak ΔH (hereinafter referred to as “temperature width of ΔH”) of 50. It is preferable that the copolymer has thermal properties satisfying the relationship that the temperature is higher than or equal to ° C., from the viewpoint of excellent fusion bonding between the ultrafine fibers in the molten state discharged from the die. If these relationships are not satisfied, the crystallization rate is too high, and the melted fibers discharged are immediately solidified, the fusion between the fibers becomes insufficient, and the strength of the obtained nonwoven fabric may decrease. is there. When the fusion between the fibers is insufficient, the strength can be increased by performing post-treatment such as calendering as described above.

The TFE-based copolymer used in the present invention having a melting endothermic peak ΔH in the range of end temperature−start temperature ≧ 50 ° C. was discharged from the die when forming the nonwoven fabric by the melt blow method. It is preferable because the ultrafine fibers in the molten state are excellent in fusing with each other.

Below this range, the crystallization speed is high.
The discharged melted fiber is likely to solidify, resulting in an inadequate fusion state, which is undesirable because the strength of the nonwoven fabric is reduced.

The melting point (Tm) of the TFE-based copolymer,
The crystallization temperature (Tc), the starting temperature of the melting endothermic peak ΔH, and the ending temperature of the melting endothermic peak ΔH are determined by a differential operation calorimeter (DSC) in a second run (sample amount 10 mg, heating and cooling rate: 10 ° C./min). The melting point (Tm) is determined from the top end of the melting endothermic peak that appears with the temperature rise, and the melting endothermic peak ΔH
With respect to the opening temperature and the ending temperature, the rising temperature of the melting endothermic peak appearing with the rise in temperature was determined as the starting temperature, and the endothermic end point of the peak was determined as the ending temperature.

From the viewpoint of production by the melt blow method, the TFE copolymer used in the present invention has a melt viscosity of 1 to 100 Pa · s immediately after being discharged from the nozzle of the extruder.
It is preferably in the range of c.

As described above, 10 μm
In order to obtain a nonwoven fabric of the following ultrafine fibers, it is desirable that the orifice diameter of the discharge section of the spinning device be 0.5 mm or less. However, even when such a fine orifice diameter is used, the fibers are fused to each other during the basis weight. Therefore, it is necessary to increase the discharge speed. In order to obtain a suitable discharge speed, the melt viscosity of the TFE-based copolymer immediately after being discharged from the nozzle of the extruder is 1 to 100 Pa · sec, and more preferably 5 to 100 Pa
· Sec, particularly preferably in the range of 5 to 30 Pa · sec. This is necessary in order to discharge with a stable ultrafine fiber diameter and to maintain high fusion strength between the fibers. The molding temperature is usually 2 points below the melting point of the TFE copolymer.
0 to 50 ° C. higher temperature.

The present invention also relates to a non-woven fabric comprising fibers obtained by using a raw material obtained by previously melting and mixing a TFE-based copolymer and a fluorine-free thermoplastic resin.
In this nonwoven fabric, fibers having an average fiber diameter of 0.5 to 10 μm are fused to each other, and the basis weight is 10 to 300 g / m ² .

The fluorine-free thermoplastic resin is not particularly limited, but is preferably incompatible with the TFE copolymer used in the present invention. This is because when the resin melted in the cooling process during spinning crystallizes, the TFE-based copolymer tends to phase-separate and emerge on the fiber surface, forming a layer rich in TFE-based copolymer on the fiber surface. This is because it is easy to take the form of the conjugated fiber. The composite fiber thus obtained is
It can be provided in a form that does not impair the chemical resistance, water repellency, release properties, antifouling properties, etc., which are the characteristics of fluororesins. The mixing ratio of the TFE-based copolymer and the non-fluorine-based thermoplastic resin is not particularly limited. Depending on the purpose, for example, the mixing ratio of the TFE-based copolymer is 0.1 to 99% by weight, preferably, 1-7
0% by weight, more preferably 1 to 50% by weight, more preferably 1 to 30% by weight.

Preferred non-fluorinated thermoplastic resins include general-purpose resins conventionally produced in the form of non-woven fabrics by a melt blow method.
(Especially, polypropylene), polyamide, polyester and the like are preferable.

The present invention also relates to a laminated fiber material obtained by laminating the above nonwoven fabric (including a nonwoven fabric of a composite fiber with a non-fluorinated thermoplastic resin) and a nonwoven fabric, woven fabric, film, sheet or the like other than the nonwoven fabric. Related to

Fluororesins, including the TFE copolymers referred to in the present invention, generally have excellent chemical resistance, water repellency, release properties, antifouling properties, and flame retardancy, but they have the mechanical strength of polyester. It is inferior to general-purpose resins such as polyamide and polyamide, and is expensive. Therefore, such a problem can be solved by laminating another material which is relatively inexpensive and has excellent mechanical strength.

Other materials to be laminated include polyolefins such as polyethylene and polypropylene, synthetic resins such as polyester, polyamide, acrylic resin and superabsorbent resin; natural materials such as cotton, wood fiber and pulp; metals such as stainless steel Other non-woven fabrics,
Woven fabrics, films, sheets and the like are suitable.

As a method of laminating the nonwoven fabric of the present invention and the above-mentioned other material, a conventionally used method can be used as it is. For example, adhesion by an adhesive, bonding by heat fusion, physical entanglement by needling, and the like can be mentioned, and may be selected according to the use and purpose.

The nonwoven fabric of the present invention is useful for various applications utilizing its properties such as chemical resistance, flame retardancy, water repellency, releasability, and stain resistance. Functionally, it can be expected to be used for various filters (filter media), moisture-permeable and waterproof materials, and flame-proof materials.

Specific examples of applications include filter materials for filter bags, electret filters, filters for coarse dust, filters for automobile air cleaners (for indoor cleaning or taking in outside air), disposable clothing, shoes, gloves, etc. Clothing materials in the field of clothing; materials in the field of protection, such as protective clothing, smoke masks, and dust masks;
Medical materials such as surgical gowns, masks, antibacterial mats, caps, sheets, etc .; Vehicle materials such as automotive interior materials and oil cleaners; Interior materials such as carpets, cushioning materials and wallpaper; Wiper materials such as wipers and cleaning materials for copiers Building materials such as waterproof coatings for roofs and house wraps; bedding materials such as futons; dry cell separators;
Battery materials such as storage battery separators; and other industrial materials, but are not limited thereto.

Further, in the present invention, in order to sufficiently exhibit the function required for the intended use, various additives and functionality-imparting agents may be added to the TFE copolymer. Such examples include antistatic agents, lubricants, release agents, colorants, and the like.

[0057]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A glass-lined autoclave having an inner volume of 174 liters was charged with 42.5 liters of water, and the inside of the autoclave was deoxygenated with a vacuum pump to an oxygen concentration of 5 ppm. Then, 1,1-dichloro-1-fluoroethane was added. And 3.4 kg of HFP were charged and the temperature in the autoclave was reduced to 3
At 5 ° C., the stirring speed was kept at 215 rpm. In addition, CH
₂ = CF (CF ₂ ) ₃ H is injected by a 0.42 kg pump, and then TFE is injected into the autoclave at a pressure of 0.83 MPaG.
, And then ethylene was charged until the internal pressure of the autoclave became 0.86 MPaG. Then, 850 g of di-n-propyl peroxydicarbonate was charged to initiate polymerization. Since the pressure decreases as the polymerization proceeds, a mixed gas of TFE / ethylene / HFP / perfluorocyclobutane (molar ratio = 62.8 / 30.4 /
2.0 / 4.8), and the polymerization pressure was increased to 0.86M.
The polymerization was continued while maintaining PaG, and CH ₂ = CF (C
F ₂ ) ₃ H was continuously charged at a ratio of 6.8% by weight based on the additional mixed gas monomer. After 20 hours of polymerization,
The contents were collected, washed with water, and dried at 120 ° C. to obtain 19 kg of a TFE-based copolymer powder.

The composition of the obtained TFE copolymer is ¹⁹ F
From NMR analysis, TFE / ethylene / HFP / CH ₂ 2C
F (CF ₂ ) ₃ H was 64.8 / 31.4 / 1.0 / 2.8 mol%.

The fluorine content in the copolymer calculated from this composition is 67.2% by weight. The melting point is 216 ° C
The melt viscosity (240 ° C.) using a Capillograph (manufactured by Toyo Seiki Seisakusho Co., Ltd., nozzle diameter: 2 mmφ, nozzle length: 10 mm) is 25.2 Pa · se at 30.4 sec ^−1.
c, at 114sec ^-1 10.8Pa · sec, at 228sec ^-1 5.
It was 2 Pa · sec. Further, the melting point and ΔH were measured by using a DSC measurement apparatus with the upper limit of the heating temperature set to 270 ° C. The temperature range of ΔH was 78 ° C.

The TFE-based copolymer was pelletized at a cylinder temperature of 220 ° C. with a 50 mmφ single screw extruder to obtain 17.5 kg of raw material pellets for forming a nonwoven fabric.

Next, using the pellets, a 30 mm single screw extruder was used to set the polymer discharge temperature to 240 ° C. and the hot air air temperature to 240 ° C. at a shear rate of 200 sec ⁻¹ , and to pass through a nozzle having an orifice diameter of 0.5 mm. It was discharged and spun while adjusting the air speed to obtain a nonwoven fabric.

The average fiber diameter of the obtained nonwoven fabric was 5.0 μm.
m, the basis weight was 60 g / m ² , and the longitudinal strength per unit weight of 100 g / m ² was 8.2 kg / 5 cm.

Example 2 A glass-lined autoclave having an inner volume of 174 liters was charged with 51 liters of water, and the inside of the autoclave was deoxygenated with a vacuum pump to an oxygen concentration of 5 ppm.
0.4 kg was charged, and the temperature in the autoclave was 35 ° C,
The stirring speed was kept at 215 rpm. Next, TFE was charged until the internal pressure of the autoclave became 0.80 MPaG, and then 3.8 kg of methanol and 190 g of di-n-propyl peroxydicarbonate were charged to initiate polymerization. Since the pressure decreases as the polymerization proceeds, TF
E was additionally injected to continue the polymerization while maintaining the polymerization pressure at 0.80 MPaG, and PMVE was continuously charged on the way to 17.5% by weight with respect to the additional TFE gas monomer. After the polymerization was performed for 29 hours, the content was recovered, washed with water, dried at 120 ° C., and then 30 kg of TFE-based copolymer powder.
I got

The composition of the obtained TFE copolymer was ¹⁹ F
From NMR analysis, TFE / PMVE = 86.9 / 13.
It was 1 mol%.

The fluorine content in the copolymer calculated from this composition is 74.5% by weight. The melting point is 227 ° C
The melt viscosity (260 ° C.) using a Capillograph (manufactured by Toyo Seiki Seisakusho Co., Ltd., nozzle diameter: 2 mmφ, nozzle length: 10 mm) is 42.3 Pa · se at 30.4 sec ^−1.
c, at 114sec ^-1 13.0Pa · sec, at 228sec ^-1 6.
It was 8 Pa · sec. In addition, the melting point and ΔH were measured with a DSC measurement device with the upper limit of the heating temperature set to 300 ° C. The temperature range of ΔH was 75 ° C.

The TFE-based copolymer was pelletized at a cylinder temperature of 250 ° C. with a 50 mmφ single screw extruder to obtain 28 kg of raw material pellets for forming a nonwoven fabric.

Next, using the pellets,
The polymer discharge temperature was set to 265 ° C. and the hot air temperature was set to 265 ° C. at a shear rate of 200 sec ⁻¹ by a single screw extruder, and discharged from a nozzle having an orifice diameter of 0.5 mm.
Spinning was performed while adjusting the air speed to obtain a nonwoven fabric.

The average fiber diameter of the obtained nonwoven fabric was 4.8 μm.
m, the basis weight was 70 g / m ² , and the longitudinal strength per unit weight of 100 g / m ² was 9.9 kg / 5 cm.

Example 3 46.6 liters of water was charged into a glass-lined autoclave having an inner volume of 174 liters, and the inside of the autoclave was deoxygenated with a vacuum pump to an oxygen concentration of 5 ppm.
48.3 kg of HFP was charged and the temperature in the autoclave was kept at 40 ° C., and the stirring speed was kept at 215 rpm. Then TF
E was charged until the internal pressure of the autoclave became 1.23 MPaG, and 85 g of di-n-propylperoxydicarbonate (methanol solvent) was charged to initiate polymerization.
Since the pressure decreases with the progress of the polymerization, TFE is additionally injected to continue the polymerization while maintaining the polymerization pressure at 1.23 MPaG, and after performing the polymerization for 34 hours, the content is recovered.
After washing with water and drying at 120 ° C., TFE copolymer powder 18
kg.

The composition of the obtained TFE copolymer is ¹⁹ F
From the NMR analysis, TFE / HFP = 89.1 / 10.9
Mole%.

The fluorine content in the copolymer calculated from this composition is 76% by weight. The melting point is 232 ° C., and the melt viscosity (265 ° C.) using a Capillograph (manufactured by Toyo Seiki Seisakusho Co., Ltd., nozzle diameter: 2 mmφ, nozzle length: 10 mm) is 46.2 Pa · m at 30.4 sec ^−1. sec,
14.1 Pa-sec at 114 sec ^-1 and 5.9 Pa at 228 sec ^-1
-It was sec. In addition, the melting point and ΔH were measured with a DSC measurement device with the upper limit of the heating temperature set to 300 ° C.
The temperature range of ΔH was 65 ° C.

The TFE-based copolymer was pelletized at a cylinder temperature of 265 ° C. using a 50 mmφ single screw extruder to obtain 16 kg of raw material pellets for forming a nonwoven fabric.

Next, using the pellets,
The polymer discharge temperature was set to 265 ° C. and the hot air temperature was set to 265 ° C. at a shear rate of 200 sec ⁻¹ by a single screw extruder, and discharged from a nozzle having an orifice diameter of 0.5 mm.
Spinning was performed while adjusting the air speed to obtain a nonwoven fabric.

The average fiber diameter of the obtained nonwoven fabric is 6.8 μm.
m, the weight per unit area was 75 g / m ² , and the longitudinal strength per unit weight per 100 g / m ² was 7.8 kg / 5 cm.

Example 4 The continuous usable temperature of the nonwoven fabric of Example 2 was set to a temperature at which the longitudinal strength per unit weight of 100 g / m 2 was reduced by half in 10,000 hours. However, the measurement of the strength is a measurement at 23 ° C.

As a result, the temperature at which the initial strength of 9.9 kg / 5 cm of the nonwoven fabric of Example 2 is reduced by half in 10,000 hours is not present below the melting point but is above the melting point. At least the continuous use temperature was a result that could be used up to the melting point of 227 ° C.

The nonwoven fabric of Example 2 was immersed in 28% aqueous ammonia at 60 ° C. for 10,000 hours, taken out, washed with water, and dried sufficiently at 120 ° C. to measure the strength of the nonwoven fabric.

As a result, 9.5 kg / 5 cm was maintained against the initial strength of 9.9 kg / 5 cm. The result was excellent in chemical resistance.

Comparative Example 1 The di-n-propyl peroxydicarbonate of Example 3 was changed to a pure product without a methanol solvent, and the charged amount was 6
Polymerization was carried out in the same manner as in Example 3 except that
g of a TFT copolymer powder was obtained.

The composition of the obtained polymer was determined by ¹⁹ FNMR to be tetrafluoroethylene / hexafluoropropylene.
It was 89.3 / 10.7 mol%.

The calculated fluorine content in the polymer is 76 wt%.

The melting point is 233 ° C.
F (manufactured by Toyo Seiki Co., Ltd. Nozzle system 2mmφ, nozzle length 1)
0mm) at 265 ° C for 30.4 sec.
c^-11515 Pa · sec, 114 sec^-1At 720
Pa · sec, 228 sec ^-1At 350 Pa · sec
there were. Next, using a 30φ single screw extruder,
Degree 200 sec^-1265 ° C polymer discharge temperature with hot air
Set the air temperature to 265 ° C and orifice 0.5m
m from the nozzle, and spin while adjusting the air speed.
Threading to obtain a nonwoven fabric.

The average fiber diameter of the obtained nonwoven fabric was 22 μm,
The basis weight was 80 g / m ² , and the longitudinal strength per unit weight of 100 g / m ² was 120 kg / 5 cm.

Comparative Example 2 The amount of PMVE charged in Example 2 was 0.7 kg, the amount of methanol charged was 5 kg, the amount of di-n-propyl peroxydicarbonate charged was 100 g, and the amount of PMVE added was 3. Polymerization was carried out in the same manner except that the content was changed to 5% by weight to obtain 30 kg of a polymer.

The composition of the obtained polymer was determined by ¹⁹ FNMR to be tetrafluoroethylene / perfluoromethylvinyl ether = 97.6 / 2.4 mol%.

The fluorine content in the copolymer calculated from this composition is 75.7% by weight.

The melting point was 297 ° C., and the temperature range of ΔH was 38 ° C.

The melt viscosity (330 ° C.) using a Capillograph (manufactured by Toyo Seiki Co., Ltd., nozzle diameter: 2 mmφ, nozzle length: 10 mm) was 20.2 Pa · s at 30.4 sec ^−1.
sec, 35.5 Pa · sec at 114 sec ⁻¹ , 22
It was 12.3 Pa · sec at 8 sec ⁻¹ .

Using this raw material, the polymer discharge temperature was set at 340 ° C., the hot air temperature was set at 340 ° C., and the orifice diameter was 0.5 mm as in Example 2 at a shear rate of 200 sec ^−1.
And spun while adjusting the air speed to obtain a nonwoven fabric.

The average fiber diameter of the obtained nonwoven fabric was 18 μm,
The basis weight was 100 g / m ² , and the longitudinal strength per unit weight of 100 g / m ² was 180 g / 5 cm.

Comparative Example 3 JP-A-7-229048 and JP-A-8-31811
No. 5 ethylene-trichlorofluoroethylene copolymer (trade name HAL, manufactured by AUSIMONT)
AR resin), melt index: 358 g / 10 min (275 ° C.)
The nonwoven fabric was obtained by setting the temperature of the hot air at 0 ° C. and the temperature of the hot air at 280 ° C.

The average fiber diameter of the obtained nonwoven fabric was 7 μm,
The basis weight was 75 g / m ² . The basis weight is 100 g / m ²
The longitudinal strength per hit was 7.2 kg / 5 cm.

This nonwoven fabric was measured for the continuous usable temperature and the chemical resistance in the same manner as in Example 4.

As a result, the strength of the ethylene-trichlorofluoroethylene nonwoven fabric is reduced by half at 120 ° C. for 10,000 hours, and the continuous usable temperature is set to 120 ° C. or less.

Also, 1% at 28 ° C. in 28% ammonia water.
After soaking for 10,000 hours, taking out, washing with water, drying sufficiently at 120 ° C., and measuring the strength of the nonwoven fabric.
m.

[0097]

According to the present invention, a filter, a heat insulating material,
Ultra-fine fiber non-woven fabric, useful as a moisture-permeable waterproof material and flame-proof material
Ultra-fine fiber non-woven fabric especially useful as a TFE-based non-woven fabric filter, heat-insulating material, moisture-permeable waterproof material, flame-resistant material, which is excellent in chemical resistance, flame retardancy, water repellency, release properties, and stain resistance. And a laminated fiber material can be provided.

Continued on the front page F term (reference) 4D019 BA13 BB03 BC11 BC12 CB06 DA03 4L035 BB31 BB40 DD13 EE04 FF01 FF05 GG01 4L047 AA18 AB10 BA08 BA23 CA04 CA05 CA06 CB10 CC01 CC12

Claims (12)

[Claims] 1. Fibers comprising a tetrafluoroethylene copolymer having an average fiber diameter of 0.5 to 10 μm are fused to each other, and have a longitudinal strength of 3.7 kg per unit weight of 100 g / m ^2. / 5 cm or more, and the basis weight of the nonwoven fabric is 10 to 300 g / m ² . 2. The nonwoven fabric according to claim 1, which is produced by a melt blow method. 3. The tetrafluoroethylene-based copolymer has a fluorine content of 55 to 76% by weight.
The described nonwoven fabric. 4. A compound of the formula (I), wherein the tetrafluoroethylene-based copolymer is tetrafluoroethylene: CF ₂ ＝ CF—Rf ¹ (I) (where Rf ¹ is CF ₃ or ORf ² (Rf ² is carbon Number 1
The nonwoven fabric according to any one of claims 1 to 3, which is a copolymer with at least one selected from perfluoroolefins represented by (5). 5. The tetrafluoroethylene-based copolymer is a copolymer of tetrafluoroethylene, ethylene and an ethylenic monomer copolymerizable therewith, wherein the copolymerizable ethylenic monomer is: Hexafluoropropylene, chlorotrifluoroethylene, formula (II): CH ₂ 2CX ¹ (CF ₂ ) nX ² (II) (where X ¹ is H or F; X ² is H, F or Cl; n
Is an integer of 1 to 10), a fluoroolefin represented by the formula:
(III): at least one selected from the group consisting of perfluorovinyl ether and propylene represented by CF ₂ ＣＦCF—ORf ² (III) (wherein Rf ² is a perfluoroalkyl group having 1 to 5 carbon atoms). The nonwoven fabric according to any one of claims 1 to 3. 6. A tetrafluoroethylene-based copolymer,
The nonwoven fabric according to any one of claims 1 to 3, which is a copolymer of tetrafluoroethylene and vinylidene fluoride. 7. A tetrafluoroethylene-based copolymer,
The nonwoven fabric according to any one of claims 1 to 3, which is a copolymer of tetrafluoroethylene, vinylidene fluoride, hexafluoroethylene, and / or chlorotrifluoroethylene. 8. The nonwoven fabric according to claim 1, wherein the melting point of the tetrafluoroethylene-based copolymer is 120 to 270 ° C. 9. The method according to claim 1, wherein the melt viscosity immediately after being discharged from the nozzle of the extrusion molding machine is formed in the range of 1 to 100 Pa · sec using the tetrafluoroethylene copolymer. The described nonwoven fabric. 10. A non-woven fabric using a raw material in which a tetrafluoroethylene-based copolymer and a fluorine-free thermoplastic resin are previously melt-mixed, wherein the average fiber diameter is 0.5 to 1
A nonwoven fabric in which 0 μm fibers are fused to each other, and the basis weight of the nonwoven fabric is 10 to 200 g / m ² . 11. The end temperature of the melting endothermic peak ΔH−the melting endothermic peak Δ
The nonwoven fabric according to any one of claims 1 to 10, wherein the nonwoven fabric is a copolymer having a thermal property satisfying a relationship of starting temperature of H ≥ 50 ° C. 12. A laminate comprising the nonwoven fabric according to claim 1 and at least one selected from the group consisting of a nonwoven fabric, a woven fabric, a film and a sheet other than the nonwoven fabric.