JP2008240170A - Conjugate yarn for reinforcing thermoplastic resin, and method for producing resin-containing strand using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conjugate yarn for reinforcing a thermoplastic resin, having excellent abrasion resistance and impregnating ability of a thermoplastic resin such as a polypropylene, to provide a method for producing a resin-containing strand by using the yarn, and to provide the resin-containing strand produced by the production method. <P>SOLUTION: The conjugate yarn for reinforcing the thermoplastic resin, comprising a core-sheath type conjugate yarn constituted of a core part and a sheath part is obtained by arranging a carbon fiber at the core part and an organic fiber having 80-200°C melting point at the sheath part, regulated so that the weight proportions of both the fibers may be 100 pts.wt. carbon fiber and 5-100 pts.wt. organic fiber. The resin-containing strand is produced by dipping the conjugate yarn for reinforcing the thermoplastic resin in a molten thermoplastic resin bath to impregnate the space of the carbon fiber of the core part with the thermoplastic resin while melting the organic fiber at the sheath part. The percentage of the weight of the carbon fiber based on the weight of the strand containing the resin produced by the method is 5-70 mass%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composite yarn for reinforcing a thermoplastic resin excellent in scratching properties and excellent in impregnation properties of a thermoplastic resin, and a method for producing a strand using the same.

  Carbon fiber and carbon fiber composite material have high tensile strength / tensile modulus, excellent heat resistance, chemical resistance, fatigue characteristics, wear resistance, low linear expansion coefficient, excellent dimensional stability, electromagnetic shielding, X Because of its excellent features such as high line permeability, it is widely applied to sports and leisure, aerospace and general industrial applications. Conventionally, a thermosetting resin such as an epoxy resin is often used as a matrix, but recently, a thermoplastic resin has attracted attention from the viewpoint of recyclability and high-speed moldability.

  Carbon fiber composite materials using thermoplastic resin as a matrix include compound pellet injection molding, resin-containing strands cut and injection molding and injection of intermediate materials for fiber reinforced resin composite materials (so-called long fiber pellets). Examples include compression molding, extrusion molding, and stamping molding using a random mat. Among them, injection molding of an intermediate material for fiber-reinforced resin composite material (so-called long fiber pellets) obtained by cutting resin-containing strands is advantageous because of high production efficiency and low processing costs.

  As a matrix of carbon fiber reinforced thermoplastic resin composite material, acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon 6, nylon 66, etc.), polyacetal, polycarbonate, polypropylene, high density polyethylene, polyethylene terephthalate, polybutylene Examples include terephthalate, polyetherimide, polystyrene, polyethersulfone, polyphenylene sulfide, polyetherketone, and polyetheretherketone. Of these thermoplastic resins, polypropylene resin is inexpensive and has excellent properties such as moldability, water resistance, chemical resistance (oil resistance, solvent resistance), and electrical insulation. Therefore, dramatic growth is expected in the future as a matrix for carbon fiber reinforced thermoplastic resin composite materials.

  Carbon fiber is composed of a large number of ultrafine filaments, and its elongation is small and fluff is likely to occur due to mechanical friction. For this reason, in order to improve the bundling property of the carbon fiber to improve the handleability and to improve the affinity with the matrix, it is common to apply a sizing agent to the carbon fiber. As such a sizing agent, for example, Patent Document 1 proposes a carbon fiber strand coated with polyurethane, and the carbon fiber strand has improved fretting properties, and a carbon fiber reinforced thermoplastic resin machine. It is said that it is possible to improve the mechanical characteristics. Further, Patent Document 2 proposes a sizing agent containing bisphenol A type epoxy resin that is liquid at normal temperature, bisphenol A type epoxy resin that is solid at normal temperature, unsaturated polyester resin, and stearic acid as essential components. Is described to give good scuffing properties to carbon fiber strands. However, the sizing agent disclosed in Patent Documents 1 and 2 has a limit in improving scratch resistance.

  On the other hand, Patent Document 3 also proposes a method of covering an organic fiber with a carbon fiber. According to this method, although the scratch resistance is improved, there is a problem that the thermoplastic resin is difficult to be impregnated and the mechanical properties of the carbon fiber reinforced thermoplastic resin composite material are deteriorated.

JP 58-126375 A JP-A-7-197381 Japanese Patent Laid-Open No. 3-113035

  An object of the present invention is to eliminate such problems of the prior art, excellent in scratching properties, and excellent in the impregnation property of thermoplastic resins such as polypropylene, and a method for producing a resin-containing strand using the same. Furthermore, it is providing the resin containing strand manufactured by this manufacturing method.

  As a result of diligent research, the present inventor has significantly improved the scratching property by covering carbon fibers with organic fibers having a specific low melting point. Moreover, when impregnating the resin, the organic fibers are melted and heated. The inventors have found that the impregnation of the plastic resin is not hindered and have completed the present invention.

The present invention for achieving the above object is as follows.
(1) A composite yarn for reinforcing a thermoplastic resin composed of a core-sheath composite yarn composed of a core part and a sheath part, wherein the core part is made of carbon fiber, and the sheath part is made of organic fiber having a melting point of 80 to 200 ° C. A composite yarn for reinforcing a thermoplastic resin, characterized in that an organic fiber is 5 to 100 parts by weight with respect to 100 parts by weight of carbon fiber, and the ratio of both fibers is 100 parts by weight.
(2) The composite yarn for reinforcing a thermoplastic resin according to (1), wherein the organic fiber is a polypropylene fiber or a polyamide fiber.
(3) The composite yarn for reinforcing a thermoplastic resin according to (1) or (2), wherein a modified polyolefin copolymer is adhered to the surface of the carbon fiber.
(4) While the organic fiber in the sheath portion is melted in the thermoplastic resin that has been melted in the thermoplastic resin-reinforced composite yarn of any one of (1) to (3), the core fiber is thermoplastic. A method for producing a resin-containing strand, comprising impregnating a resin.
(5) The method for producing a resin-containing strand according to (4), wherein the thermoplastic resin is a polypropylene resin.
(6) A resin-containing strand produced by the production method of (4) or (5) above, wherein the carbon fiber is blended in an amount of 5 to 70 mass% with respect to the thermoplastic resin.

  Since the composite yarn for reinforcing a thermoplastic resin of the present invention is covered with an organic fiber, the scratch resistance is greatly improved. Moreover, since melting | fusing point of an organic fiber is 80-200 degreeC, a resin containing strand can be shape | molded, melting the organic fiber of a sheath part.

The composite yarn for reinforcing thermoplastic resin of the present invention (hereinafter sometimes referred to as composite yarn) is composed of a core-sheath type composite yarn composed of a core portion and a sheath portion.
As the carbon fiber used for the core in the present invention, any carbon fiber such as polyacrylonitrile (PAN), petroleum / coal pitch, rayon, and lignin can be used. In particular, PAN-based carbon fibers using PAN as a raw material are preferable because they are excellent in productivity and mechanical properties on an industrial scale.

  The PAN-based carbon fiber has a bundle shape of about 1000 to 50000 filaments having a diameter of about 6 to 8 μm, and is manufactured through the following four steps. First, in the first flameproofing step, the acrylic fiber is heated in an air atmosphere at 200 to 300 ° C., the nitrile group is closed, oxygen is introduced into the acrylic polymer, and a stable structure is obtained even at high temperatures.

In the carbonization step, the carbon fiber is baked at a high temperature of 1000 ° C. or higher in an inert gas atmosphere to increase the carbon content to 90% by mass or higher.
In the carbon fiber, an oxygen-containing functional group may be introduced on the surface of the carbon fiber by a surface treatment in order to improve the adhesion with the thermoplastic resin.

  Examples of the carbon fiber surface treatment include chemical liquid oxidation / electrolytic oxidation in a liquid phase, gas phase oxidation, and the like. Among these surface treatments, an electrolytic oxidation treatment in a liquid phase is preferable from the viewpoint of productivity and treatment uniformity. Examples of the electrolytic solution used for the electrolytic oxidation treatment include inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid, inorganic hydroxides such as sodium hydroxide and potassium hydroxide, and inorganic salts such as ammonium sulfate, sodium carbonate, and sodium bicarbonate. Can be mentioned.

  As an index for the surface treatment of carbon fiber, it is better to manage it by the surface oxygen concentration ratio (O / C) of carbon fiber that can be measured using X-ray photoelectron spectroscopy (ESCA). It is preferable to perform electrolytic oxidation treatment so as to be 0.05 to 0.4.

  The carbon fiber may be provided with a sizing agent in order to improve the handleability of the carbon fiber and improve the affinity between the carbon fiber and the thermoplastic resin. Examples of the sizing method for carbon fiber include a spray method, a roller dipping method, and a roller transfer method. Among these sizing methods, a roller dipping method excellent in productivity and uniformity is preferable. When the carbon fiber strand is immersed in the sizing liquid, the opening and squeezing are repeated through an immersion roller provided in the sizing bath, and the sizing liquid is impregnated into the strand. After impregnating the sizing liquid between the carbon fibers, the moisture or solvent is removed by a subsequent drying process to obtain carbon fibers to which the desired sizing agent is applied. The amount of the sizing agent attached to the carbon fiber is adjusted by adjusting the concentration of the sizing liquid or adjusting the squeezing roller. For drying the carbon fiber, for example, hot air, a hot plate, a roller, an infrared heater or the like can be used.

  The sizing solution is a modified polyolefin copolymer having at least one selected from an ethylene-propylene copolymer, a propylene-butene copolymer, and an ethylene-propylene-butene copolymer as a main chain and graft-modified with an unsaturated carboxylic acid. A sizing solution containing a polymer, a modified polypropylene resin having polypropylene as a main chain and graft-modified with an unsaturated carboxylic acid, or a resin composition obtained by mixing these, is preferable. It is preferable that 0% by mass is given. Thereby, it becomes easy to impregnate a thermoplastic resin, especially a polypropylene resin between carbon fibers, and the mechanical physical property of a carbon fiber reinforced thermoplastic resin composite material becomes favorable.

In the composite yarn of the present invention, it is important that the carbon fiber is disposed in the core and the organic fiber having a melting point of 80 to 200 ° C. is disposed in the sheath.
The composite yarn of the present invention is used for resin reinforcement of a thermoplastic resin, but in the process until the composite yarn is blended with the thermoplastic resin, the carbon fiber is covered with organic fiber, so that the carbon fiber becomes fuzzed by abrasion, It is possible to prevent deterioration in process passability (yield). Furthermore, when the composite yarn is blended or immersed in the hot melted thermoplastic resin, the organic fiber having the melting point of the sheath is melted and the thermoplastic resin enters between the carbon fibers. A resin-containing strand or carbon fiber reinforced thermoplastic resin composite material sufficiently impregnated with a thermoplastic resin therebetween can be obtained.

  Therefore, the melting point of the organic fiber needs to be 80 to 200 ° C, preferably 80 to 150 ° C. When the melting point of the organic fiber exceeds 200 ° C., the organic fiber is not melted even if the composite yarn is blended or impregnated in the heat-melted resin, and it becomes difficult to impregnate the thermoplastic resin between the carbon fibers. On the other hand, if the melting point of the organic fiber is less than 80 ° C., it is not preferable because the organic fiber melts due to heat by rubbing.

  The composite yarn of the present invention is a composite yarn in which the carbon fiber is disposed in the core and the organic fiber is disposed in the sheath. At this time, from the viewpoint of scratching and the impregnation property of the thermoplastic resin, the organic fiber with respect to 100 parts by weight of the carbon fiber is preferably 5 to 100 parts by weight, and more preferably 5 to 50 parts by weight. If the organic fiber is less than 5 parts by weight, good scratching properties cannot be obtained. Moreover, when an organic fiber exceeds 100 weight part, the impregnation property of a thermoplastic resin will worsen, and the mechanical physical property of a carbon fiber reinforced thermoplastic resin composite material will worsen.

Examples of the organic fiber having a melting point of 80 to 200 ° C. include fibers made of a polymer such as polyester, nylon, or polyolefin such as polyethylene or polypropylene. Polyesters can also have a low melting point by copolymerizing components such as isophthalic acid, terephthalic acid and sulfoisophthalic acid. Also, nylon 11, nylon 12, and copolymerized polyamides such as nylon 6/66, nylon 6/610, nylon 6/612, nylon 6/11, nylon 6/12, nylon 66/610, nylon 66/612, nylon 66/11, Nylon 66/12, Nylon 610/612, Nylon 610/11, Nylon 610/12, Nylon 612/11, Nylon 11/12 and other binary copolymer polyamides, Nylon 6/11/66, Nylon 6 / 11/610, nylon 6/11/612, nylon 6/12/66, nylon 6/12/610, nylon 6/12/612, nylon 6/66/610, nylon 6/66/612, nylon 6 / 610/612, nylon 11/66/610, nylon 11/66/612, nai Ternary copolymer polyamides such as nylon 12/66/610, nylon 12/66/612, nylon 11/12/66, nylon 11/12/610, nylon 11/12/612, nylon 66/610/612, nylon 6/11/12/66, nylon 6/11/12/610, nylon 6/11/12/612, nylon 6/11/66/610, nylon 6/12/66/610, nylon 11/12/66 / 610, Nylon 11/12/66/612, Nylon 12/66/610/612 and other fibers made of polymers such as quaternary copolymerized polyamides are also compared to nylon 6 fibers and nylon 66 fibers, which are the same polyamides. Low melting point.
The organic fiber preferably has a fineness of 20 to 1600 dtex, and the number of filaments is preferably 10 to 500.

  In producing the composite yarn of the present invention, a known covering machine or the like can be used. The covering for covering the carbon fiber with the organic fiber may be single covering or double covering, and a known single covering machine or double covering machine can be used in the production. In the production of the above-mentioned composite yarn, a carbon fiber supply rate of 1 to 20 m / min can be preferably employed.

  As described above, the composite yarn of the present invention can be suitably used as a reinforcing yarn for thermoplastic resin. As thermoplastic resins, acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon 6, nylon 66, etc.), polyacetal, polycarbonate, polypropylene, high density polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyetherimide, polystyrene , Polyethersulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone and the like, and polypropylene is particularly preferable.

  In order to produce a resin-containing strand using the composite yarn of the present invention described above, the composite yarn is immersed in a molten thermoplastic resin bath, and the core organic fiber is melted while melting the core. It can manufacture by the method of impregnating a thermoplastic resin between the carbon fibers of a part. For example, FIG. 2 is a schematic view schematically showing an example of a method for producing a resin-containing strand, but continuously in a thermoplastic resin bath 8 set in a thermostat 7 kept at a specific temperature. Then, the excess resin is squeezed out by the squeezing roller 4 on the bathing side to produce a resin-containing strand. The obtained resin-containing strand (carbon fiber reinforced strand prepreg) can be suitably used as an intermediate material for a carbon fiber reinforced thermoplastic resin composite material.

  The weight of the carbon fiber in the resin-containing strand varies depending on the form of the carbon fiber, the molding method of the composite material, the application, etc., but in the range of 5 to 70% by mass with respect to the weight of the resin-containing strand from the viewpoint of cost performance. Is preferable, and 20-40 mass% is more preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples. Each characteristic value was measured by the following method.

(1) Abrasive fluff amount of composite yarn for reinforcing thermoplastic resin As shown in FIG. 1, five stainless steel round bars B with a diameter of 2 mm were arranged in a zigzag manner. The interval between the stainless steel round bars B was 15 mm, and the folding angle α of the thermoplastic resin reinforcing composite yarn A was 120 °. The composite yarn A for thermoplastic resin reinforcement was zigzag between stainless steel round bars, and the unwinding tension of the composite yarn for thermoplastic resin reinforcement was set to 1.96 N (200 gf) from the bobbin and rubbed. The composite yarn for reinforcing thermoplastic resin after rubbing is sandwiched between two urethane sponges (dimensions 32 mm x 64 mm x 10 mm, mass 0.25 g), and a 125 g weight is placed on the entire surface of the urethane sponge so that a load is applied, and thermoplasticity The mass of fluff adhering to the sponge when the composite yarn for resin reinforcement was passed for 2 minutes at a speed of 15 m / min was defined as the amount of fuzz.

(2) Impregnation property of thermoplastic resin Using the apparatus shown in FIG. 2, a polypropylene resin bath 8 (width 10 cm × length 30 cm) in which a composite yarn 1 for thermoplastic resin reinforcement is set in a thermostat 7 held at 260 ° C. ) At a speed of 30 cm / min. As the polypropylene resin, a homopolypropylene general-purpose injection molding grade and a melt flow rate of 13 g / 10 min were used. Next, excess resin was squeezed out by a squeezing roller 4 on the bathing side to produce a resin-containing strand (carbon fiber reinforced strand prepreg), which was wound up by a winder 6. In the obtained resin-containing strand, the weight of the carbon fiber relative to the weight of the strand (the content of the carbon fiber in the strand) was 30% by weight. In FIG. 2, 2 is a guide roller, 3 is an immersion roller, and 5 is a composite yarn package for thermoplastic resin reinforcement. The resin-containing strand was cut to a length of 6 mm, then hardened with an epoxy resin, and the cross-section was observed with an SEM. Here, when the polypropylene resin was impregnated between the carbon fibers, it was marked with ◯, when there was an unimpregnated portion, Δ, and when not impregnated, it was marked with ×.

(3) Measurement of melting point Using a differential scanning calorimeter (DSC-910 model manufactured by DuPont), measurement was performed by heating at a heating rate of 10 ° C./min in a nitrogen gas atmosphere.

[Example 1]
To a double covering machine, carbon fiber of 4000 dtex carbon fiber “Besfight HTK-6K” (manufactured by Toho Tenax) and 110 dtex / 12 fil low melting point nylon fiber “Flor M” (manufactured by Unitika) having a melting point of 125 ° C. Was supplied at a rate of 15 m / min, and a composite fiber for reinforcing a thermoplastic resin was produced in which the carbon fiber was double covered with a low-melting nylon fiber, and the carbon fiber was arranged in the core and the low-melting nylon fiber was arranged in the sheath. . At this time, the covering number of the low melting point nylon to the carbon fiber was adjusted so that the weight of the low melting point nylon fiber was 15 parts by weight with respect to 100 parts by weight of the carbon fiber. The composite yarn for reinforcing thermoplastic resin was evaluated for the amount of fuzz and the impregnation property of the thermoplastic resin. The results are shown in Table 1.

[Example 2]
The same procedure as in Example 1 was carried out except that the covering number of the low melting point nylon fiber was changed and the weight of the low melting point nylon fiber was changed to 20 parts by weight with respect to 100 parts by weight of the carbon fiber. The results are shown in Table 1.

[Example 3]
The same procedure as in Example 1 was conducted, except that the covering number of the low melting point nylon fiber was changed and the weight of the low melting point nylon fiber was changed to 37 parts by weight with respect to 100 parts by weight of the carbon fiber. The results are shown in Table 1.

[Comparative Example 1]
It replaced with the composite yarn for thermoplastic resin reinforcement, and it carried out similarly to Example 1 except having used only the carbon fiber of 4000 dtex "Besphite HTK-6K" (made by Toho Tenax). The results are shown in Table 1.

[Comparative Example 2]
Instead of the low melting point nylon fiber, a 235 dtex / 34 fill nylon fiber (manufactured by Unitika) having a melting point of 223 ° C. was used, and the covering number of the nylon fiber was changed so that the weight of the nylon fiber was changed to 100 parts by weight of the carbon fiber. The procedure was the same as Example 1 except that the amount was 20 parts by weight. The results are shown in Table 1.

  Since the composite yarn for reinforcing a thermoplastic resin of the present invention is covered with an organic fiber, the scratch resistance is greatly improved. Moreover, since melting | fusing point of an organic fiber is 80-200 degreeC, a resin containing strand can be shape | molded, melting the organic fiber of a sheath part. Moreover, according to the manufacturing method of this invention, the resin containing strand which resin contained enough between carbon fibers can be manufactured easily. Therefore, the resin-containing strand of the present invention obtained by the production method and the composite yarn of the present invention can be suitably used for reinforcing a thermoplastic resin.

It is the schematic which showed the evaluation method of the impregnation property of the thermoplastic resin in an Example. It is the schematic which shows an example (The measuring method of the amount of abrasion fuzz of the thermoplastic resin denture composite yarn in an Example) of the manufacturing method of the resin containing strand of this invention.

Explanation of symbols

A: Composite yarn for reinforcing thermoplastic resin B: Stainless steel round bar 1: Composite yarn for reinforcing thermoplastic resin 2: Guide roller 3: Dipping roller 4: Drawing roller 5: Composite yarn for reinforcing thermoplastic resin package 6: Winder 7: Thermostatic bath 8: Polypropylene resin bath

Claims (6)

  A composite yarn for reinforcing thermoplastic resin composed of a core-sheath type composite yarn composed of a core part and a sheath part, wherein carbon fibers are arranged in the core part and organic fibers having a melting point of 80 to 200 ° C. are arranged in the sheath part. And the weight ratio of both fibers is 5-100 weight part of organic fiber with respect to 100 weight part of carbon fiber, The composite yarn for thermoplastic resin reinforcement characterized by the above-mentioned.   The composite yarn for reinforcing a thermoplastic resin according to claim 1, wherein the organic fiber is a polypropylene fiber or a polyamide fiber.   The composite yarn for reinforcing a thermoplastic resin according to claim 1 or 2, wherein a modified polyolefin copolymer is attached to the surface of the carbon fiber.   The thermoplastic resin reinforcing composite yarn according to any one of claims 1 to 3 is immersed in a molten thermoplastic resin bath, and the organic fiber in the sheath is melted, while the thermoplastic resin is interposed between the carbon fibers in the core. A method for producing a resin-containing strand, characterized by impregnating a resin.   The method for producing a resin-containing strand according to claim 4, wherein the thermoplastic resin is a polypropylene resin.   The resin-containing strand produced by the production method according to claim 4 or 5, wherein the weight of the carbon fiber is 5 to 70 mass% with respect to the weight of the resin-impregnated strand.

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