JP4810481B2 - Composite yarn and intermediate for fiber reinforced resin and fiber reinforced resin molded body using the same - Google Patents

Description

  The present invention relates to a composite yarn for fiber reinforced resin containing natural fibers, an intermediate, and a fiber reinforced resin molded product using the same.

Plastic is used for the interior of automobiles, airplanes, vehicles, etc., and is lighter than metal. Since plastic alone is insufficient in strength, glass short fibers (cut to a certain length) are mixed in the plastic. However, when discarded, if it is burned in an incinerator, the plastic decomposes into CO ₂ and water, but the glass melts and hardens and adheres to the inside of the incinerator. As a result, there is a concern that the life of the incinerator is significantly reduced. Carbon fiber is known as a material having high strength such as glass, but there is a problem that it is expensive and cannot be used for practical use.

  Therefore, in recent years, a fiber-reinforced thermoplastic resin molded body (FRTP) made of natural fibers has been attracting social interest. This means that it can be recycled and can be used repeatedly as material recycling, that there is no toxic gas at the time of combustion as thermal recycling, and that it is possible to reduce the weight of the moving body due to energy problems. For example, plant-based natural fibers absorb carbon dioxide in the interior during photosynthesis, and the carbon dioxide that is emitted even when burned is the same as the original.

Patent Documents 1 and 2 propose fiber reinforced resins using natural fibers as reinforcing fibers. Patent Document 1 describes that hemp fiber short fibers are processed into a non-woven fabric, woven fabric, and knitted fabric to obtain a fiber reinforced resin. Patent Document 2 describes that kenaf fiber short fibers are processed into a non-woven fabric and a woven fabric. It is described that a fiber reinforced resin is used.
JP 2004-143401 A JP 2004-149930 A

  However, Patent Documents 1 and 2 use a short fiber such as hemp fiber or kenaf fiber to process into a nonwoven fabric, woven fabric, or knitted fabric and melt-mix with the resin or impregnate it into a fiber reinforced resin (FRP). However, there is a problem that a resin is difficult to permeate, a large-scale apparatus is required, and molding is not easy. In particular, natural fibers have a lower decomposition temperature than glass fibers and carbon fibers, and the thermoplastic resin used as a matrix resin cannot be heated to a viscosity that facilitates penetration, so the problem of permeability is very important. Met.

  In order to solve the above-mentioned conventional problems, the present invention facilitates penetration of the resin into the natural fiber yarn, has good moldability, has no environmental problems, has high strength, and has uniform physical properties. A body and a fiber-reinforced resin molded body using the same are provided.

Fiber-reinforced resin composite yarn of the present invention, one or a plurality of yarns comprising a natural fiber as a core yarn, the fiber-reinforced resin (FRP) composite yarn obtained by covering the periphery of a synthetic resin fiber yarn of the core yarns A composite yarn for fiber reinforced resin, in which a plurality of yarns are aligned and covered with the synthetic resin fiber yarn, and the synthetic resin fiber yarn is a thermoplastic synthetic resin material that becomes a matrix resin when FRP is used. And

  The intermediate body for fiber reinforced resin of the present invention is characterized in that the composite yarn for fiber reinforced resin is a woven fabric, a knitted fabric, a multi-axis inserted warp knitted fabric, or a braided fabric.

  The fiber-reinforced resin molded article of the present invention is obtained by press-molding the intermediate for fiber-reinforced resin by heating to a temperature not lower than the melting point of the synthetic resin fiber yarn and not higher than 20 ° C. below the decomposition temperature of the natural fiber. .

  Another fiber-reinforced resin molded article according to the present invention has the composite yarn for fiber-reinforced resin arranged in at least one direction and heated to a temperature not lower than the melting point of the synthetic resin fiber yarn and not higher than 20 ° C. below the decomposition temperature of the natural fiber. And press-molded.

  In the present invention, one or a plurality of yarns containing natural fibers are used as a core yarn, and the synthetic yarn is covered with a thermoplastic synthetic resin fiber yarn that becomes a matrix resin when the periphery of the core yarn is FRP. As a result, the contact area between the core yarn and the covering yarn can be increased, and when heated above the melting point of the thermoplastic synthetic resin, the molten thermoplastic synthetic resin quickly infiltrates into the natural fiber yarn and melts with the natural fiber yarn. The composite integration of the thermoplastic synthetic resin is efficiently performed. That is, the resin easily penetrates into the fiber yarn. As a result, a fiber reinforced resin having good moldability, high strength, and uniform physical properties can be obtained. Moreover, since the natural fiber is used, the environmental problem at the time of disposal can be eliminated. Furthermore, by using a natural fiber yarn, it can be handled as a continuous fiber, and the volume content (Vf) can be improved. Moreover, even if there are individual differences peculiar to natural fibers and differences in harvested places, stable physical properties can be obtained by mixing in the pre-spinning process.

  In the present invention, one or a plurality of yarns containing natural fibers are used as a core yarn, and the periphery of the core yarn is covered with a synthetic resin fiber yarn to obtain a composite yarn for fiber reinforced resin (FRP). The synthetic resin fiber yarn is a thermoplastic synthetic resin material that becomes a matrix resin when FRP is used. In this case, the covering yarn (synthetic resin fiber yarn) is melted and becomes an FRP matrix resin as it is by hot press molding with the composite yarn aligned in a predetermined direction. The molten thermoplastic synthetic resin quickly penetrates into the natural fiber yarn, and the composite integration of the natural fiber yarn and the molten thermoplastic synthetic resin is efficiently performed.

  In the present invention, it is very preferable to further align a plurality of the FRP composite yarns and cover the periphery with the synthetic resin fiber yarns. Normally, thick yarns tend to have poor resin permeability, but in this way, thick yarns with good resin permeability can also be used. And even if the yarn having a large fineness is used, the composite integration of the natural fiber yarn and the molten thermoplastic synthetic resin can be efficiently performed.

  The synthetic fiber yarn may be further added to the core yarn or the plurality of FRP composite yarns. If it does in this way, the composite integration of the natural fiber and molten thermoplastic synthetic resin in the inside between natural fiber yarns can be performed efficiently.

  The natural fiber that can be used in the present invention is preferably a plant-based natural fiber, and specifically includes cotton fiber, hemp fiber, kenaf fiber, bamboo fiber, kapok and the like. In particular, flax yarn (linen) fibers or hemp fibers such as ramie are preferred. This is because hemp fiber can be harvested as an annual grass in 3 months, and the supply of raw materials is stable. The hemp fibers can be used in a state having an equilibrium moisture content. This is because the strength can be kept high with an equilibrium moisture content.

  The thermoplastic synthetic resin fiber yarn that can be used in the present invention is preferably a resin that is usually used as a matrix resin for FRP and has a melting point lower than the decomposition temperature of natural fibers. For example, when hemp fibers are used as natural fibers, a resin having a melting point of 200 ° C. or lower is preferable. Examples of such thermoplastic synthetic resin fiber yarn include polypropylene (PP), polyethylene (PE), and copolymers thereof, copolymerized polyesters, copolymerized polyamides, polyvinyl chloride, polyvinylidene chloride, copolymerized polyacetals, There are fibers such as polylactic acid and polybutyl succinate.

  The blend ratio of the natural fiber yarn and the synthetic fiber yarn is preferably in the range of natural fiber yarn: synthetic fiber yarn = 70: 30 to 30:70 by weight ratio. Within this range, the composite integration of the natural fiber yarn and the molten thermoplastic synthetic resin can be performed efficiently.

  The composite yarn for fiber reinforced resin of the present invention can be made into FRP by aligning the yarn itself by a roving method or the like. In addition, a woven fabric, a knitted fabric, a multi-axis inserted warp knitted fabric, or a braided fabric may be used as an intermediate for fiber reinforced resin. These intermediates can also be prepregs for use in the final molded body. Woven fabrics, knitted fabrics, and multi-axis inserted warp knitted fabrics can be used in the form of sheets, and braids can be used in the form of pipes. The woven and knitted fabric can be any known tissue.

  In order to produce such a molded body, the mold temperature is heated to a temperature not lower than the melting point of the synthetic resin fiber yarn and not higher than 20 ° C. below the decomposition temperature of the natural fiber, and press-molded. Also, the composite yarn for fiber reinforced resin is arranged in at least one direction, and the mold temperature is heated to a temperature not lower than the melting point of the synthetic resin fiber yarn and not higher than 20 ° C. lower than the decomposition temperature of the natural fiber, and press-molded. A fiber-reinforced resin molded product can also be obtained. In particular, in consideration of the impregnation property of the thermoplastic resin into the natural fiber, it is preferable to mold at a temperature within the above-mentioned temperature range, for example, a temperature 20 to 40 ° C. lower than the decomposition temperature. When hemp fibers are used as natural fibers, the mold temperature is preferably 200 ° C. or lower, and more preferably 160 to 180 ° C.

  The fiber-reinforced thermoplastic resin molded body can use a conventionally known molding method, and examples thereof include a hot stamping method, a prepreg molding method, and an SMC molding method. You may shape | mold by the film stacking method which melted and compressed the film of the thermoplastic resin.

  Next, it demonstrates using drawing. FIG. 1 is a perspective view of a composite yarn for fiber reinforced resin in one embodiment of the present invention. The composite yarn 10 for fiber reinforced resin is covered with a synthetic resin fiber yarn 12 around a natural fiber yarn 11 of one core yarn. The natural fiber yarn 11 may be any one of twisted yarn, untwisted yarn, untwisted yarn, bundled yarn, sliver yarn and the like. The synthetic resin fiber yarn 12 may be a filament yarn or a spun yarn. A filament yarn is preferable in terms of cost. The filament yarn can be used as a multifilament or a monofilament. The fineness of the natural fiber yarn 11 and the synthetic resin fiber yarn 12 can be used in the range of 10 to 1,000 tex.

  Next, FIG. 2 is a perspective view of a composite yarn for fiber-reinforced resin in another embodiment of the present invention. The composite yarn 13 for fiber reinforced resin is covered with a synthetic resin fiber yarn 12 around the natural fiber yarns 11a to 11c of three core yarns.

  Next, FIG. 3 is a perspective view of a composite yarn for fiber reinforced resin in still another embodiment of the present invention. The composite yarn 16 for fiber reinforced resin is obtained by covering the periphery of each of the four core fiber natural fiber yarns 11a to 11d with the synthetic resin fiber yarns 12a to 12d and the synthetic resin fiber 14 serving as a matrix resin as the core yarn. The outer periphery is covered with a synthetic resin fiber yarn 15. In this example, the synthetic resin fiber 14 may not be used.

  Next, FIG. 5 is a conceptual perspective view of a multi-axis inserted warp knitted fabric. Natural fiber yarns (for example, flax yarn spun yarns) 1a to 1f arranged in a plurality of directions are stitched (bundled) in the thickness direction by stitching yarns 7 and 8 hung on the knitting needle 6 and integrated. ing. Such a multi-axis inserted warp knitted fabric can be used as a fiber reinforced intermediate, and can be subjected to hot press molding. This multiaxial laminated sheet can obtain a fiber-reinforced plastic having an excellent reinforcing effect in multiple directions. A binder may be used instead of or in combination with the stitching yarn.

  The present invention will be specifically described below with reference to examples. In addition, this invention is not limited to the following Example.

(Example 1)
In this example, a composite yarn 16 having a structure as shown in FIG. 3 was produced. First, the ramie spun yarns (143tex) 11a to 11d were covered with 340d PP filament yarns 12a to 12d using a covering machine. Four yarns are arranged, four PP filaments 14 are arranged in the center, and one composite yarn 16 is formed by covering the PP filament yarns 15 with a covering machine so as to put them together. . S55 was gently twisted so that the structure did not collapse during the last processing. The ratio of the ramie spun yarn and the PP yarn (primary covering + secondary covering + core yarn) was 50:50 by weight.

  During the first covering, an operation of returning the twist of the spun yarn by performing a reverse rotation twist with the spun yarn 11a to 11d was performed. Since the twists of the spun yarns 11a to 11d were Z200, they were set as follows.

これらの糸を用いて、プレス法により成形体を作成した。図６Ａは本発明の一実施例の加熱プレス法による成形体の製造方法を示す平面図、図６Ｂは同製造方法の断面図である。メタルフレーム２に、複合糸１ａ，１ｂを図６Ａのように一方向に巻き付けた。複合糸の巻きつけ本数は、幅２０ｍｍに対し１３２本、巻きつけ重量３．１ｇであった。なお、図６Ａにあるとおりメタルフレーム２に一定間隔を置いて２カ所巻き付けた。この巻きつけた複合糸に、図６Ｂに示すように、熱プレス金型４，５によってラミー紡績糸とＰＰフィラメント糸を加熱加圧し、溶融一体化させた。ＰＰフィラメント糸の融点が１３４℃、ラミー紡績糸の分解温度約２００℃であったので、金型温度は１６０℃とし、圧力は１０ＭＰａ、時間を１０分とした。

Using these yarns, a molded body was prepared by a pressing method. FIG. 6A is a plan view showing a method for producing a molded body by a hot press method according to an embodiment of the present invention, and FIG. 6B is a cross-sectional view of the production method. The composite yarns 1a and 1b were wound around the metal frame 2 in one direction as shown in FIG. 6A. The number of wound composite yarns was 132 for a width of 20 mm, and the wound weight was 3.1 g. As shown in FIG. 6A, the metal frame 2 was wound at two places at regular intervals. As shown in FIG. 6B, the ramie spun yarn and the PP filament yarn were heated and pressed by the hot press dies 4 and 5 to melt and integrate the wound composite yarn. Since the melting point of the PP filament yarn was 134 ° C. and the decomposition temperature of the ramie spun yarn was about 200 ° C., the mold temperature was 160 ° C., the pressure was 10 MPa, and the time was 10 minutes.

  The obtained molded product was cut into a length of 180 mm to prepare a tensile test piece (length 180 mm, width 20 mm, thickness about 1.2 mm). The tensile test was conducted according to JISK7054: 1995 using an autograph (manufactured by Shimadzu Corporation: AG-5000B) at a distance between grips of 80 mm and a test speed of 1 mm / min. The tensile test results of these molded products are shown below.

これらの結果から弾性率の大きな差異はないが、強度の点で加工時の解撚操作をしない方が良いことがわかった。

From these results, it was found that there is no great difference in elastic modulus, but it is better not to perform the untwisting operation during processing in terms of strength.

  Moreover, when each cross section of the molded body was observed with a microscope, it was found that all of A, B, and C were in the same state, and the resin impregnation was not affected even when untwisted. Furthermore, it was found that in each molded body, the spun yarn gathered portion and the matrix resin portion were clearly separated.

(Example 2)
Next, the same 143 tex ramie spun yarn as in Example 1 was used and covered with PP filament yarn. A composite yarn was prepared using the same three yarns in the same manner as in Example 1.

  Using this yarn, a molded body was produced by the press method in the same manner as in Example 1.

  The tensile test results of these molded products are shown below in comparison with the results in Table 2.

実験番号ニの樹脂の含浸状態は、イ〜ハと同様であったが、紡績糸がマトリックス樹脂に均一に分散していることが解った。

The impregnation state of the resin of Experiment No. D was the same as that of A to C, but it was found that the spun yarn was uniformly dispersed in the matrix resin.

(Example 3)
As shown in FIG. 2, three 42 tex ramie spun yarns (Z420) were aligned and covered with PP filament yarns. Further, four of these were aligned to form a composite yarn covered with PP filament yarn 15 so that the structure did not collapse as shown in FIG. The ratio of ramie spun yarn and PP yarn (total of primary covering + secondary covering) was 50:50 by weight.

  The molding conditions were the same as in Example 1. The melting point of the PP filament yarn was 134 ° C, and the decomposition temperature of the ramie spun yarn was about 200 ° C. The pressure was 10 MPa and the time was 10 minutes. In this example, experiment number E was used.

  The tensile test results of these molded products are shown below in comparison with the results of Examples 1-2.

実験番号ホの含浸状態はイ〜ニと同様だが、ホでは紡績糸がマトリックス樹脂により均一に分散していることが解った。

Although the impregnation state of Experiment No. E is the same as that of (i) to (ii), it was found that the spun yarn was uniformly dispersed by the matrix resin.

  From these results, it is possible to improve the elastic modulus and strength by thinning the spun yarn, and also to combine a plurality of matrix resin and spun yarn into a composite yarn, so that the base material is manufactured using a thin spun yarn. It was found that the manufacturing time can be shortened. Also in the molding process, since the matrix resin and the reinforcing fibers are already combined in a certain ratio in the state of the reinforced base material, it is not necessary to introduce the matrix resin at the time of molding, and the process can be greatly omitted. Further, since the matrix resin is compounded in each layer, there is an advantage that the time for molding is shortened.

FIG. 1 is a perspective view of a composite yarn for fiber reinforced resin in one embodiment of the present invention. FIG. 2 is a perspective view of a composite yarn for fiber reinforced resin according to another embodiment of the present invention. FIG. 3 is a perspective view of a composite yarn for fiber-reinforced resin in still another embodiment of the present invention. FIG. 4 is a perspective view of a composite yarn for fiber-reinforced resin in still another embodiment of the present invention. FIG. 5 is a conceptual perspective view of a multi-axis inserted warp knitted fabric showing an application example of the present invention. FIG. 6A is a plan view showing a method for producing a molded body by a hot press method according to an embodiment of the present invention, and FIG. 6B is a cross-sectional view of the production method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a-1f Spun yarn 2 which consists of hemp fiber Metal frame 3a-3d Polypropylene (PP) film 4,5 Hot press die 6 Knitting needle 7,8 Stitching yarn 10,13,16 Composite yarn 11 for fiber reinforced resin, 11a to 11d Core yarn 12 made of natural fiber yarn, 12a to 12d Covering yarn made of synthetic resin fiber yarn 14 Core yarn made of synthetic resin fiber yarn 15 Outer covering yarn made of synthetic resin fiber yarn

Claims (7)

One or a plurality of yarns containing natural fibers are used as a core yarn, and a plurality of composite yarns for fiber reinforced resin (FRP) in which the periphery of the core yarn is covered with a synthetic resin fiber yarn are arranged, and the periphery thereof is the synthetic resin. It is a composite yarn for fiber reinforced resin covered with fiber yarn,
A composite yarn for fiber-reinforced resin, wherein the synthetic resin fiber yarn is a thermoplastic synthetic resin material that becomes a matrix resin when FRP is used. The composite yarn for fiber reinforced resin according to claim 1, wherein the synthetic fiber yarn is further added to the core yarn or the plurality of FRP composite yarns. The natural fiber yarns, fiber-reinforced resin composite yarn according to claim 1 or 2, spun yarn of hemp. The mixing ratio of the synthetic fiber yarn and the natural fiber yarns, natural fiber yarns in a weight ratio: synthetic yarn = 70: 30-30: 70 fiber according to any one of claims 1 to 3, which is a range of Composite yarn for reinforced resin. An intermediate for fiber reinforced resin, wherein the composite yarn for fiber reinforced resin according to any one of claims 1 to 4 is a woven fabric, a knitted fabric, a multi-axis inserted warp knitted fabric, or a braid. A fiber reinforced resin molded product obtained by press-molding the intermediate for fiber reinforced resin according to claim 5 at a mold temperature to a temperature not lower than the melting point of the synthetic resin fiber yarn and not higher than 20 ° C lower than the decomposition temperature of the natural fiber. body. The composite yarn for fiber reinforced resin according to any one of claims 1 to 4 is arranged in at least one direction, and a mold temperature is not lower than a melting point of the synthetic resin fiber yarn and not more than a temperature 20 ° C lower than a decomposition temperature of the natural fiber. A fiber-reinforced resin molded product that is heated and pressed.

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