JP2002115173A - Method for producing fiber-reinforced thermoplastic resin wire rod and fiber-reinforced thermoplastic resin pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of producing fiber-reinforced thermoplastic resin wire rods and a fiber-reinforced thermoplastic resin pellet having improved mechanical characteristics such as flexural characteristics, impact resistance characteristics, etc., by firmly bonding a spun yarn of natural plant fiber to a thermoplastic resin to integrate the spun yarn with the thermoplastic resin. SOLUTION: In producing fiber-reinforced thermoplastic resin wire rods by combining a thermoplastic resin with a spun yarn of natural plant fiber as a reinforcing fiber, when the spun yarn is impregnated with the thermoplastic resin or at least before the spun yarn is impregnated with the thermoplastic resin, the spun yarn is subjected to a plasma treatment or an ozone treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced thermoplastic resin wire obtained by using a natural vegetable fiber spun yarn as a reinforcing fiber and combining it with a thermoplastic resin, and a pellet obtained by cutting the wire. In particular, a natural plant fiber spun yarn is tightly bonded and integrated with a thermoplastic resin, and as a fiber reinforced composite material, a fiber reinforced thermoplastic resin wire rod and a pellet with improved mechanical properties such as flexural strength, flexural modulus and impact resistance It relates to the manufacturing method.

[0002]

2. Description of the Related Art Recently, studies on fiber-reinforced resins using natural plant fibers such as wood pulp, hemp, palm and bamboo as reinforcing fibers have been actively conducted. Incidentally, in recent years, awareness of waste pollution has been increasing, and natural fiber reinforced resin has an impact on the human body due to scattering of detached glass fiber, which is seen when disposing of reinforced resin products using glass fiber as reinforcing fiber. Also, there is no concern about it, and even in the case of incineration, all can be recovered as thermal energy, and furthermore, there is no generation of residual ash or generation of harmful gas derived from inorganic fillers such as glass fiber or talc. It is.

[0003] However, natural plant fibers are non-continuous in comparison with continuous fibers such as glass fibers, carbon fibers, metal fibers, and various synthetic fibers which have been widely used as reinforcing fibers for fiber-reinforced resins. Therefore, a special technique is required to combine this with a resin to obtain a fiber-reinforced composite material utilizing the characteristics of long fibers. For example, a continuous strand of long fibers can be continuously impregnated and taken into a molten resin bath, cooled, and the resin can be solidified to continuously produce a fiber-reinforced resin wire. Is cut to an arbitrary length, so that fiber-reinforced resin pellets can be produced with high productivity. However, non-continuous natural plant fibers must be used as twisted spun yarns, requiring special techniques.

[0004] In addition, mineral oil is attached to the spun yarn of ordinary natural plant fiber by mineral oil treatment for smoothly performing the spinning process, and this impairs the integrity with the resin to be composited. A method has been studied in which natural vegetable fibers are subjected to an alkali treatment, a sulfuric acid treatment, an acetylation treatment, or the like to remove mineral oil, improve adhesion to a resin, and increase integrity. However, in these methods, a large amount of liquid is generated in the preliminary treatment for improving the adhesiveness, so that a great deal of labor and cost are required for wastewater treatment.

In addition, a method using a thinner for removing mineral oil (“The 1st Kansai Private University Science and Technology High Tech Research
Academic Frontier Joint Symposium, 1999)
However, it does not solve the problem of waste liquid treatment, and there is a concern about fire and adverse effects on the human body. Also, as a general method of removing mineral oil attached to the fiber surface, there is a method of using washing water or steam containing a surfactant, but since treatment with water or steam is inherently hydrophilic, plant fibers are hydrophilic. It absorbs remarkably water and requires a lot of energy and time to dry. Moreover, since a large amount of water vapor or water is used for cleaning, and a large amount of heat energy is required for removing water after cleaning, waste of resources and energy is inevitable.

[0006] On the other hand, a method of applying ozone treatment or discharge plasma treatment to textiles is described in, for example, Japanese Patent Application Laid-Open No. 7-11 / 1995
565, 6-57660, 9-471
Many methods have been proposed, such as Japanese Patent Application Publication No. 6 and Japanese Patent Application Publication No. 11-217766. However, these methods are all aimed at improving fiber refining, bleaching, shrinkage resistance, dyeing properties, water absorbency, etc., and as in the present invention, a natural vegetable fiber spun yarn is used as a thermoplastic resin and There is no intent to increase the joint integrity of the device.

[0007] In addition, generally, a method of applying an ozone treatment, a plasma treatment, a corona treatment, or the like to a synthetic resin film such as a polyolefin resin, a molded product, a fiber, or the like to improve the adhesiveness, the coating property, the dyeing property, and the like. Although it is known, there is no example in which natural plant fiber spun yarn is used in a process for enhancing the composite integrity with a thermoplastic resin.

[0008]

SUMMARY OF THE INVENTION Under the above-mentioned prior art, the present inventors have focused on a natural plant fiber, which has recently been used as a reinforcing fiber, and used it as a reinforcing fiber. When compounding with a plastic resin to produce fiber-reinforced resin wires and pellets for molding, the above-mentioned problems, especially continuous productivity, quality stability as molding material, strength characteristics as molded products, etc. can be satisfied. We have been conducting research with the aim of developing fiber-reinforced thermoplastic resin wires and pellets. Therefore, an object of the present invention is to effectively utilize natural plant fibers as the main reinforcing fibers, and to achieve continuous productivity, quality stability as a molding material, and fiber-reinforced thermoplastics capable of satisfying all the strength characteristics as a molded article. An object of the present invention is to provide a method for producing a resin wire and a pellet.

[0009]

Means for Solving the Problems The manufacturing method of the present invention, which can solve the above-mentioned problems, relates to a method of manufacturing a fiber reinforced thermoplastic resin wire obtained by combining a natural resin fiber spun yarn as a reinforcing fiber with a thermoplastic resin. When, or at least before, impregnating the spun yarn with a thermoplastic resin, the spun yarn is subjected to a plasma treatment or an ozone treatment to increase the bonding force between the natural plant fiber and the thermoplastic resin, thereby increasing the composite reinforcing material. There is a gist in enhancing the strength characteristics of the steel.

In carrying out the above method, when performing the plasma treatment or the ozone treatment, a force in the direction of untwisting is applied to the spun yarn of the natural plant fiber, and the plasma treatment or the ozone treatment is performed by loosening the spun yarn. If applied, these treatment effects can be exerted to the inside of the spun yarn, and are therefore recommended as a preferred embodiment when practicing the present invention. In the case of a polyolefin-based resin containing an acid-modified polyolefin as the thermoplastic resin, the physical properties can be further improved by joining and integrating the natural vegetable fiber and the thermoplastic resin. It is preferable because it can be used for

The above-mentioned natural plant fiber reinforced thermoplastic resin wire obtained by the present invention is obtained by heating and reshaping the wire in a longitudinal direction by aligning the wire in the longitudinal direction, or by winding the wire on the inner surface or the outer surface of a mold. In addition, it can be used effectively as a molding material that can be heated and re-formed into an arbitrary shape from a non-woven fabric or a woven or knitted fabric, and the wire is cut into an appropriate length to form a pellet, extruded or injected. It can be used as a molding material for molding and the like.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the present invention, when producing a fiber reinforced thermoplastic resin wire rod in which a natural vegetable fiber spun yarn is composited with a thermoplastic resin, the spun yarn is impregnated with the thermoplastic resin. Or at least before that, the spun yarn is subjected to a plasma treatment or an ozone treatment to activate the fibers constituting the spun yarn, thereby increasing the bonding property with the thermoplastic resin, thereby increasing the composite integrity of the two. The method is characterized in that it is enhanced. Hereinafter, the production method of the present invention will be described in detail mainly on these processes.

[0013] The plasma treatment and the ozone treatment employed in the present invention activate the surface of the natural vegetable fiber spun yarn composited with the thermoplastic resin and decompose oils and the like adhering to the spun yarn. This is performed to increase the bonding strength between the thermoplastic resin and the spun yarn of the natural plant fiber. By the treatment, the integrity of the bonding between the spun yarn and the natural plant fiber is significantly improved. The molded product obtained by the subsequent processing has excellent performance in bending strength, flexural modulus, impact resistance and the like.

The plasma treatment or ozone treatment itself is not a novel treatment method, but is used for scouring and bleaching of fibers as described above, and also for improving shrink resistance, dyeing properties, water absorption and the like.
However, as far as the present inventors know, when the natural vegetable fiber spun yarn is combined with a thermoplastic resin as a reinforcing fiber as described above, the surface activity of the spun yarn is increased together with the surface cleaning together with the thermoplastic resin to improve the surface activity. There has been no example in which plasma treatment or ozone treatment is employed to enhance the joining integrity of a secondary molding material having excellent strength characteristics as intended in the present invention (that is, a composite resin wire for secondary molding). And pellets), and provide a technique that is extremely useful as a fiber-reinforced composite material.

The method of plasma treatment or ozone treatment employed in the present invention is not particularly special, and may be carried out by appropriately modifying known methods. In the present invention in which a fiber spun yarn is to be processed, it is desirable to appropriately control the processing conditions in consideration of the suppression of deterioration due to ozone oxidation from the following viewpoints.

That is, low-temperature plasma treatment is employed as the plasma treatment method. However, in order to provide a sufficient surface activation effect while preventing thermal degradation of natural plant fibers as much as possible, the treatment is carried out at room temperature (0 to 40 ° C.). (Approximately).

As the ozone treatment method, a method of blowing an ozone-containing gas, a method of blowing an ozone-containing gas into a molten resin, and the like can be adopted. The most common method is an ozone-containing gas (oxygen in a raw material is discharged by discharging. This is a method of spraying ozone-containing gas obtained by ozonation. The temperature conditions at that time are not particularly limited, but in order to provide a sufficient surface activating effect while preventing ozone deterioration of natural plant fibers as much as possible, it is usually possible to treat at around normal temperature (0 to 40 ° C). desirable.

The above-mentioned plasma treatment or ozone treatment should be performed at least before immersing the spun natural vegetable fiber in a thermoplastic resin bath. Usually, a strand in which a plurality of the spun yarns are aligned is continuously heated. When performing impregnation by immersion traveling in a thermoplastic resin bath, a device for plasma treatment or ozone treatment is provided immediately before or upstream of the thermoplastic resin bath, and these treatments are continuously performed at that position. Is performed.

The spun yarn is Z-twisted or S-twisted to secure tension as an aggregate of short fibrous natural plant fibers. Among them, Z-twisting is generally used. When performing the treatment, the twist is given in a direction opposite to the twist direction of the spun yarn within a range that can guarantee the tension necessary for continuous running, and the treatment is performed so as to widen the inter-fiber gap of the spun yarn. This is preferable because the action of plasma treatment or ozone treatment can be exerted even inside the spun yarn.

Further, if the treatment is performed in a state where the twist is released in this way and then the thermoplastic resin is impregnated immediately downstream thereof,
It is preferable because the impregnation of the thermoplastic resin between the fibers is also promoted, and the problem of insufficient strength due to insufficient impregnation is solved.

After the plasma treatment or the ozone treatment, the continuous strand impregnated with the thermoplastic resin is drawn through a nozzle in a high temperature state in which the thermoplastic resin is maintained in a molten state. Is added to control the resin impregnation amount, and the air caught in the spun yarn is extruded to the outside. Therefore, when this is cooled and solidified, it is possible to obtain a fiber-reinforced thermoplastic resin wire having no void defects inside. The impregnation of the fiber with the thermoplastic resin and the drawing of the continuous strand can be performed by the methods described in, for example, JP-A-64-16612, JP-A-1-263005, and JP-A-5-169445.

The thus obtained fiber reinforced thermoplastic resin wire of the present invention is activated by purifying the surface of the spun yarn of natural plant fiber constituting the reinforcing fiber by plasma treatment or ozone treatment and is activated. Since the bonding strength is increased, the integration between the two is enhanced, and the fiber-reinforced composite material exhibits excellent strength characteristics.

The natural plant fiber spun yarn used in the present invention includes flax, ramie, manila hemp, sisal, jute, hemp, kenaf, ramie, coconut fiber,
Examples include spun yarns such as cotton, panya cotton, and shiroko, which can be used alone or in combination of two or more if necessary. When a plurality of types are used in combination, a plurality of types may be combined and spun, or when a single type of spun yarn is combined (impregnated) with a thermoplastic resin, a plurality of types may be aligned and combined. . The selection of the natural plant fiber may be appropriately selected depending on the physical properties expected of the molded article finally obtained.

The thickness of the spun yarn is not particularly limited.
Jute number specified in SL0101 (constant length type)
It is preferable to use a yarn of 5-80 count (a spun yarn having a weight of 1 kg at 29,029 m is referred to as a first count). If the thickness of the spun yarn is smaller than 5th, the strength of the spun yarn as a whole tends to be insufficient, and it is easy to cause cutting during impregnation and takeover, which may hinder stable continuous operation. On the other hand, if an excessively thick spun yarn exceeding 80 count is used, the resin is insufficiently impregnated, the dispersion of the fibers during molding becomes poor, and the mechanical properties of the molded product tend to be uneven and insufficient. Come up.

Further, when the fiber reinforced resin wire obtained by impregnating and taking off the molten resin and then cooling is cut, and then cut into pellets to form a molding material, fluff is liable to be generated. Not only is there a risk of polluting the environment,
When the pellets are put into a hopper such as an injection molding machine, brittleness is liable to occur in the hopper due to the fluff generated, which may hinder continuous molding. In consideration of such points, the lower limit of the spun yarn is more preferably 7 or more, more preferably 10 or more, and the upper limit of the more preferable count is 70 or less, more preferably 50 or less.

The content of the spun natural plant fiber used as the reinforcing fiber is at least 10% by mass, more preferably at least 12% by mass, based on the total amount of the fiber-reinforced resin wire.
It is preferably at most 65% by mass, more preferably at most 60% by mass. When the content of the natural plant fiber spun yarn is less than 10% by mass, the elastic modulus of the fiber-reinforced resin material tends to be insufficient due to a shortage of the absolute amount of the reinforcing fiber, and when the content exceeds 65% by mass, the spun yarn becomes excessively large. There is a tendency that impregnation of the resin into the resin becomes insufficient.

The present invention is characterized in that spun yarn of natural plant fiber is used as the reinforcing fiber as described above, but a small amount of spun yarn of natural plant fiber is used together with the spun yarn of natural plant fiber within a range not to impair the characteristics of the present invention. Synthetic organic fibers or carbon fibers can be used in combination. When these fibers are discarded, the synthetic organic fibers can be recovered as heat energy, and even if both the synthetic fibers and the carbon fibers are incinerated, no residual ash is generated, which impairs the material advantage of the present invention. There is no.

As the synthetic organic fibers that can be used, those that are optimal in relation to the melting and softening temperature of the thermoplastic resin used and the heat resistance of the synthetic organic fibers may be selected. It is not particularly limited as long as it has, for example, preferred are polypropylene fibers, polyamide fibers, polyester fibers, polyimide fibers, polyarylate fibers, polycarbonate fibers, syndiotactic polystyrene fibers, Examples thereof include polyalkylene paraoxybenzoate fibers. These synthetic fibers can be used alone or in combination of two or more if necessary. These synthetic organic fibers and carbon fibers are used for multifilament roving of continuous fibers in order to prevent the yarn breakage by supplementing the tension applied to the spun yarn when the natural vegetable fiber spun yarn is impregnated and run in a molten resin bath. It is desirable to use

Among the above-mentioned synthetic organic fibers, polyester fibers such as polyethylene terephthalate fiber and polybutylene terephthalate fiber, and polyamide fibers such as polyamide 6 and polyamide 6.6 are particularly preferable in view of physical properties and cost. Polyethylene terephthalate fibers are optimal.

In the case of polyethylene terephthalate, it is particularly preferable to use fibers having a strength of 4.44 dtex (4 g / denier) or more, preferably 6.7 dtex (6 g / denier) or more in order to improve the impact resistance.

The diameter of the synthetic organic fiber may be determined according to the handleability at the time of producing a fiber reinforced resin wire or cutting it to produce a pellet, or the strength characteristics of a molded product obtained by using the wire or the pellet. In consideration of the above, it is preferably 0.5 μm or more, more preferably 1 μm or more, and 100 μm or less, more preferably 50 μm or less.

As the carbon fiber, pitch type, PAN
Any type of system may be used, and the diameter is not particularly limited, and may be appropriately selected according to the use and characteristics of the final product, but is generally in the range of 6 to 20 μm, more generally in the range of 7 to 15 μm. 3,000 to 100,000 of these are aligned and used.

When the natural vegetable fiber spun yarn or the synthetic organic fiber or carbon fiber is passed through a thermoplastic resin bath for impregnation, the spun yarn is passed through the resin bath in a twisted state, and the downstream of the twisted state. When pulling out from the nozzle etc. on the side,
By adjusting the drawing amount of the molten resin, drawing is performed while controlling the resin content of the obtained impregnated strand to 20 to 90% by mass, more preferably 30 to 88% by mass.

In the present invention, the thermoplastic resin serving as a matrix component preferably has a melt softening temperature of 220.
It is desirable to select a material having a temperature of about ℃ or lower, more preferably about 200 ° C or lower, and further preferably about 180 ° C or lower. The reason is that if the melt softening temperature of the thermoplastic resin is too high, the spun yarn is exposed to a high temperature when the resin bath in a molten state is impregnated with the spun yarn, causing thermal decomposition and thermal degradation. This may cause the function as a reinforcing fiber to be impaired. From such a viewpoint, preferable thermoplastic resins include polyolefin resins such as polypropylene and polyethylene, polyamide resins, polyester resins, polystyrene resins, AS resins, and polylactic acid-based biodegradable resins. Homopolymer resins and copolymer resins as described above, as well as blend resins using two or more thereof are exemplified as preferable ones.
The selection of the thermoplastic resin is arbitrarily selected in consideration of the required properties of the fiber-reinforced resin wire or pellet obtained as the final product, and the molded product obtained by using these.

Among the above-mentioned thermoplastic resins, particularly preferred in consideration of the balance of strength characteristics, cost, etc., are polypropylene, high-density polyethylene, linear low-density polyethylene, low-density polyethylene, butene-1, hexene-
1, polyolefin resins such as α-olefin polymers such as octene-1, or copolymers thereof, modified polyolefin resins modified with unsaturated carboxylic acids or derivatives thereof, or blend resins of two or more thereof It is.

Examples of the unsaturated carboxylic acids or derivatives thereof used in the above modification include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, esters of these acids, maleic anhydride, itaconic anhydride and the like. Particularly preferred are maleic anhydride and glycidyl methacrylate.

Further, in the present invention, it is desirable to use a crystalline thermoplastic resin in order to suppress the odor generated by the thermal decomposition of the lignin component and the like which may be contained in the spun natural vegetable fiber yarn. Higher crystallinity is preferred. This is because an odor component is taken into the crystallized portion and an effect of suppressing odor is expected. From these viewpoints, among the resins, polypropylene and high-density polyethylene, which are highly crystalline plastics, are recommended as preferable ones.

In the present invention, the affinity between the spun yarn and the thermoplastic resin is enhanced by the lignin contained in the natural plant fiber, and the uniformity and high integrity are obtained in combination with the above-described plasma treatment and ozone treatment. Although pellets can be obtained, it is also effective to add various modified resins having good affinity for both the fiber and the resin in order to further improve the adhesion between the reinforcing fiber and the thermoplastic resin. For example, when a maleic anhydride-modified polyolefin, an oxazoline-modified polyolefin, a glycidyl methacrylate-modified polyolefin, or the like is added to a polyolefin-based resin, the integrity of the composite material is further enhanced, and the physical properties of a molded article can be expected to be improved. The amount of the modified polyolefin resin added at that time varies depending on the resin system and the degree of modification, but in the case of a polypropylene resin, the acid value is 26.
The addition amount of the maleic anhydride-modified polypropylene resin of mgKOH / g is 0.1 to
It is 15% by mass, more preferably 0.2 to 12% by mass, and still more preferably 0.5 to 10% by mass.

Various additives can be added to the thermoplastic resin serving as the matrix depending on the physical properties and applications required of the molded article. These additives include dispersants, lubricants, flame retardants, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, carbon black, crystallization accelerators (thickeners), plasticizers, pigments, dyes And the like, and these can be used in combination of two or more as necessary.

The fiber reinforced thermoplastic resin wire according to the present invention has excellent secondary workability due to the properties of the thermoplastic resin constituting the matrix. For example, a large number of such wires are aligned or used in a mold. A method of winding around the inner and outer surfaces, heating and melting to re-mold, cutting the fiber to an arbitrary length and pelletizing it, using it as a raw material for extrusion molding or injection molding, or making it into a chopped strand, a nonwoven fabric or a woven or knitted fabric It can be effectively used as various molding materials, such as being used as a molding material for secondary processing.

The preferred pellet length when used as a pellet-shaped molding material is in the range of 2 to 24 mm.
In the case of a short object of less than 2 mm, the reinforcing fiber becomes short, and it becomes difficult to obtain sufficient strength characteristics. Conversely, if the length exceeds 24 mm, the pellet causes a bridge in a hopper at the time of molding, resulting in a stable supply. And smooth molding cannot be performed. From such a viewpoint, the more preferable length when used as a pellet is 3 mm or more, more preferably 4 mm or more, 15 mm or less, and further preferably 12 mm or less.

The diameter of the pellet is 1 mm or more and 5 mm or less, more preferably 2 mm or more and 4 mm or less, in consideration of the productivity of the pellet itself and the ease of handling at the time of molding using the pellet.

When the preferred size of the pellet is expressed by the relationship between the pellet length (L) and the pellet diameter (D), L / L
It is preferable that D (aspect ratio) is 1 or more and 6 or less. If the L / D of the pellets is less than 1, the pellets may be cracked when the impregnated / pulled wire is cut into pellets, and the fuzzing of the reinforcing fibers becomes remarkable, resulting in poor handling properties. In addition, L of the pellet
When / D exceeds 6 and the pellet is excessively elongated, the reinforcing fiber is liable to be broken when the pellet is caught by a screw or the like during molding, and the reinforcing fiber length is shortened to obtain a molded product having sufficient strength characteristics. It becomes difficult. From such a viewpoint, the more preferable L / D of the pellet is 2 or more and 5 or less.

Although natural plant fibers vary depending on the type, they generally tend to undergo thermal degradation near 180 ° C. Therefore, when a thermoplastic resin having a high melting point and softening point is used, It is desired to consider the deterioration of the reinforcing fibers including the heat resistance of the synthetic organic fibers that may be used together. The molten resin temperature at the time of impregnating the reinforcing fiber with the resin is preferably low, but the balance between the degree of resin impregnation into the reinforcing fiber and the resin viscosity exerting on the take-up speed of the strand (reinforced fiber bundle impregnated with the resin). In consideration of the above, the optimum temperature is selected.

In selecting the thermoplastic resin, a resin having a melt viscosity suitable for impregnating the reinforcing fibers is selected, and the thermoplastic resin is heated to a temperature at which the melt viscosity becomes sufficiently low as much as possible. Melts. For example, in the case of a polypropylene resin, the melt flow rate (MFR: 230 ° C., 2.16 kgf) is 5 g / 10 min or more, more preferably 15 g / 10 min or more, still more preferably 30 g / 10 min or more as a guide. 200 g / 10 min or less, more preferably 150 g / 10 min or less, further preferably 1 g / min
It is better to select one that is at least 00 g / 10 minutes.

If the MFR of the polypropylene resin is less than the above range, the productivity of reinforced resin wires and pellets containing spun natural vegetable fiber tends to be low, and even if it can be produced, impregnation of the reinforced fiber with the resin is not possible. As a result, the reinforcing fibers are likely to fall off from the obtained pellets, causing a problem in handleability, and the dispersion of the strength characteristic values tends to increase due to poor dispersibility of the reinforcing fibers as a molded product. On the other hand, if the MFR exceeds the above-mentioned preferable range, the properties such as the strength, elastic modulus and heat resistance of the molded product are undesirably reduced.

When jute spun yarn is selected as the reinforcing fiber, the molten resin temperature of the polypropylene resin is 200 ° C. or higher and 280 ° C. or lower, preferably 220 ° C. or higher and 260 ° C. or lower, more preferably 23 ° C. or lower.
The temperature is preferably from 0 ° C to 255 ° C.

At this time, from the viewpoint of suppressing the thermal deterioration of the reinforcing fibers, the time required for the reinforcing fibers to enter the molten resin bath and be taken out from the nozzle is controlled within 10 seconds, preferably within 5 seconds. Is preferred. If this time is too long, the possibility that the reinforcing fibers undergo thermal degradation increases. On the other hand, if this time is too short, the impregnation of the thermoplastic resin becomes insufficient. Therefore, it is desirable to secure the immersion time preferably at least 0.1 second, more preferably at least 0.15 second.

[0049]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to experimental examples. However, the present invention is not limited to the following examples, and may be appropriately changed within a range that can conform to the purpose of the preceding and the following. And these are all included in the technical scope of the present invention.

Experimental Example A fiber-reinforced thermoplastic resin wire was manufactured by the following materials and processing method.

[Polypropylene resin] The density is 0.91
g / cm^Three, MFR (230 ° C, 2.16 kgf) is 6
Homopoly with 0 g / 10 min, melting point (DSC method) at 165 ° C
To 100 parts by mass of propylene resin (PP), anhydrous maleic
Acid-modified polypropylene resin (trade name, manufactured by Sanyo Chemical Industries, Ltd.)
"UMEX 1001", acid value: 26 mgKOH /
g, density: 0.95 g / cm ^Three, Molecular weight: 40,000
(Weight average molecular weight by GPC method)
Resin pellets were used.

[Polyamide 12 resin] The density is 1.01 g
/ Cm ³ , nylon 12 having a melting point (DSC method) of 178 ° C.
Resin (trade name “DAIDAMID L1” manufactured by Daicel Huls)
640 ").

[Natural vegetable fiber] As a natural vegetable fiber spun yarn, a spun yarn of jute (jute yarn) of No. 30 (Z twist)
It was used.

[Plasma Treatment] A plasma irradiator (controller ST-7000, head ST-7010, atmospheric plasma method) manufactured by KEYENCE CORPORATION was used.

[Ozone-containing gas treatment] Ozone generator (“OZO-4”, manufactured by Toyo Kakoki Co., Ltd., ozone generation amount:
(400 mg / h, concentration: 300 ppm), the generated ozone is injected into a glass tube, and a reinforcing fiber spun yarn is passed therethrough while being twisted (S twisted) in a direction of untwisting. This ozone-containing gas treatment is repeated three times in series.

Examples 1 to 5 and Comparative Examples 1 to 3 A method in which the three spun natural vegetable fiber yarns are impregnated by being passed through a molten resin bath (250 ° C.) while being twisted, and withdrawn at a line speed of 15 m / min. Is adopted. At this time, after performing the plasma irradiation treatment while applying the twist (S twist) in the direction of untwisting, the above-mentioned polypropylene-based resin bath (Example 1) or polyamide 1 melted immediately downstream thereof
2 Dipped and run in a resin bath (Example 2), then withdrawn from the discharge nozzle, cooled and solidified, and had a diameter of about 3 mm.
To produce a natural plant fiber reinforced resin wire having a fiber content of about 40% by mass. Thereafter, the wire was cut into a length of 4 mm to produce a natural plant fiber reinforced resin pellet having a diameter of about 3 mm x a length of 4 mm and a fiber content of about 40% by mass. Further, a natural plant fiber reinforced resin wire was produced in exactly the same manner as in Example 1 except that the ozone-containing gas treatment was used instead of the plasma irradiation treatment, and subsequently, the length was cut to about 4 mm, thereby A natural plant fiber reinforced resin pellet having the same dimensions and impregnation rate as in Example 3 was produced (Example 3).

In the above, natural vegetable fiber reinforced resin pellets were produced in the same manner as in Examples 1 and 2 except that the plasma treatment or the ozone treatment was omitted (Comparative Examples 1 and 2).
2).

In the above, a resin bath was prepared in the same manner as in Example 1 except that the spun yarn was irradiated with plasma from two directions (two units) while twisting the natural vegetable fiber spun yarn in the Z twist direction. (Polypropylene-based resin) was immersed and run to produce a natural plant fiber reinforced resin wire rod, and subsequently cut to a length of about 4 mm to produce a natural plant fiber reinforced resin pellet having the same dimensions and impregnation rate as described above. (Example 4).

Also, a natural plant fiber reinforced resin wire was produced in the same manner as in Example 1 except that only a polypropylene resin containing no maleic anhydride-modified polypropylene resin was used as the polypropylene resin.
Subsequently, by cutting into a length of about 4 mm, natural vegetable fiber reinforced resin pellets having the same dimensions and impregnation rate as described above were produced (Example 5).

Further, a natural plant fiber reinforced resin wire rod was produced in the same manner as in Example 1 except that a polypropylene resin containing no maleic anhydride-modified polypropylene resin was used, and both the plasma irradiation treatment and the ozone-containing gas treatment were omitted. Was manufactured and subsequently cut to a length of about 4 mm to produce natural vegetable fiber reinforced resin pellets having the same dimensions and impregnation rate as described above (Comparative Example 3).

[Evaluation Test] Each of the natural plant fiber reinforced resin pellets obtained above was dried for 3 hours using a blow dryer at 100 ° C., and a molding experiment was performed using these as molding materials. As a molding device, an injection molding machine “SG220U-SYCAP / MIIIA” manufactured by Sumitomo-Nestal Co., Ltd. is used, and a molding temperature is 180 ° C. for a resin using a polypropylene-based resin, and a molding temperature for a resin using a polyamide 12 resin. Injection molding was performed at a temperature of 200 ° C. and a mold temperature of 60 ° C., and a bending test piece (25 mm × 130 mm × thickness 3.2) was formed.
mm) and an impact test piece (12.7 mm × 62 mm × thickness 3.2 mm) were manufactured, and the following evaluation tests were performed on each of them to obtain the results shown in Table 1.

Evaluation test method: Flexural strength and flexural modulus: Measured according to ASTM D790 Impact value: Notched Izod impact test conducted according to ASTM D256

[0063]

[Table 1]

From Table 1, it can be analyzed as follows.

From the comparison between Examples 1, 3, and 4 and Comparative Example 1, and from the comparison between Example 5 and Comparative Example 3, when the polypropylene resin was used as the matrix component, the spun yarn was subjected to plasma treatment or ozone treatment. It can be seen that physical properties can be significantly improved. From the comparison between Example 1 and Example 5, when an acid-modified propylene-based resin is added as a matrix resin, a clear synergistic effect with plasma treatment or ozone treatment is recognized.

Further, Examples 1 (an improvement of 13.9% in bending strength and 18.4% in bending elastic modulus) and Example 4 (4.2% in bending strength and 4% in bending elasticity) with respect to Comparative Example 1 were obtained. .1
% Improvement), the effect of improving the physical properties differs depending on the direction of twisting at the time of resin bath impregnation, and a higher effect of improving the physical properties can be obtained by performing the impregnation while twisting in the direction of untwisting. .

Further, from a comparison of Comparative Example 2 with Example 2 (4.8% improvement in flexural strength and 6.1% flexural modulus), the effect of improving physical properties was recognized even when polyamide 12 resin was used. However, Example 1 with respect to Comparative Example 1 (13.9% improvement in flexural strength and 18.4% in flexural modulus), and Example 5 with Comparative Example 3 (8.5 in flexural strength)
% And the flexural modulus is improved by 14.6%), the modification effect is smaller than that in the case of using a polypropylene resin. The reason is that polyamide originally has good adhesion to natural fibers, whereas polypropylene resin originally has poor adhesion to natural fibers. It is considered that the quality treatment (ozone treatment or plasma treatment) effect was more effectively exerted.
That is, in the present invention, when a polyolefin-based resin is used as the resin to be combined with the spun natural plant fiber yarn, it is more effectively utilized.

[0068]

The present invention is constituted as described above. A spun yarn of natural vegetable fiber is used as a main reinforcing fiber and the spun yarn is subjected to plasma treatment or impregnation before impregnation with a thermoplastic resin bath. By performing the ozone treatment, the joining integrity between the spun yarn and the thermoplastic resin can be improved, and physical properties such as bending strength, bending elastic modulus, and impact characteristics can be effectively improved. Moreover, according to this method, the problem of waste liquid treatment pointed out in the conventional adhesion improving treatment (chemical treatment such as steam treatment, detergent treatment, alkali treatment, sulfuric acid treatment, etc.) can be solved and treatment cost can be greatly reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 101: 12 B29K 105: 12 105: 12 311: 10 311: 10 C08L 23:00 C08L 23:00 D06M 101: 04 D06M 101: 04 B29C 67/14 L (72) Inventor Tatsuya Tanaka 2-3-1, Shinhama, Araimachi, Takasago-shi, Hyogo Inside Kobe Steel, Ltd. Takasago Works (72) Inventor Tadashi Kumagiri, Takasago, Hyogo Prefecture 2-3-1, Shinhama, Arai-cho, Ichigo F-term (reference) in Kobe Steel, Ltd. Takasago Works 4F072 AB03 AB24 AC01 AC02 AD04 AD53 AG06 AG14 AH04 AH31 AK04 4F201 AA01 AA03J AB25 BA02 BL08 BL44 4F205 AA01 AB25 AD06 AD32 AD33 HA05 HA06 HA34 HA36 HA43 HB02 HC03 HC12 HE21 HE25 HM03 4L031 AA02 AB21 CB05 CB09 DA21

Claims (4)

[Claims] When producing a fiber reinforced thermoplastic resin wire rod obtained by combining a natural resin fiber spun yarn as a reinforcing fiber with a thermoplastic resin, at least before or after impregnating the spun yarn with the thermoplastic resin, A method of producing a fiber-reinforced thermoplastic resin wire, wherein the spun yarn is subjected to a plasma treatment or an ozone treatment. 2. The method according to claim 1, wherein, when the plasma treatment or the ozone treatment is performed, a force in the direction of untwisting is applied to the spun natural vegetable fiber yarn. 3. The method according to claim 1, wherein the thermoplastic resin is a polyolefin resin containing an acid-modified polyolefin. 4. A method for producing fiber-reinforced thermoplastic resin pellets, comprising cutting a wire produced by the method according to claim 1 into pellets.