JP2009067879A - Fiber-reinforced thermosetting resin molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fiber-reinforced thermosetting resin molded bodies using spun yarns comprising plant natural fibers preferable from the view point of recycling and having high strength and uniform physical properties. <P>SOLUTION: The fiber-reinforced thermosetting resin molded bodies reinforced with natural fibers are provided, wherein the natural fibers are plant natural fibers such as spun yarns comprising cottons, hemps, bamboos, kapok or the like and the spun yarns are at least unidirectionally aligned and monolithically molded with a thermosetting resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fiber-reinforced thermosetting resin molded body obtained by combining natural fibers and a thermosetting resin, and in particular, spinning plant-based natural fibers (collecting a certain amount of fibers and twisting them into yarns). It is related with the fiber reinforced thermosetting resin molding using the continuous yarn which becomes.

  Conventionally, as fiber-reinforced plastics, those obtained by impregnating reinforcing fibers such as carbon fibers and glass fibers with a thermosetting resin or a thermoplastic resin are used. However, glass fiber is an incombustible material, which causes a problem of causing a decrease in combustion efficiency and damaging the incinerator. Furthermore, since it is a mixture of an inorganic substance and an organic substance, it is not preferable from the viewpoint of recycling.

Therefore, in recent years, there has been an increasing social interest in fiber reinforced resin molded products (FRP) made of natural fibers. 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.

In recent years, fiber reinforced plastics using plant-based natural fibers have been proposed. For example, a fiber reinforced resin composition formed by blending a resin material and natural fibers surface-treated with a compatibilizing agent at a predetermined ratio, and heating and kneading such a mixture under predetermined conditions is provided. It can be seen (Patent Document 1). In addition, by using yarn-like kenaf fibers, warps and wefts are alternately slid up and down alternately to form a woven fabric having a plain weave structure, and liquid unsaturation is obtained by laminating this woven fabric. The thing impregnated with the polyester resin is also seen (patent document 2).
JP 2004-114436 A JP 2004-143401 A

  However, when natural fibers as described in the above-mentioned patent document are cut into about 4 to 5 mm are used as they are, it is not preferable for improvement of mechanical properties which is the original purpose as fiber reinforcement performance. . In addition, when the fiber reinforced resin (FRP) is processed into a nonwoven fabric, a woven fabric, or a knitted fabric using short fibers such as hemp fiber or kenaf fiber, the fiber volume content (Vf) in the FRP cannot be increased in the nonwoven fabric. However, there was a problem that the strength was not obtained and the molded product was thick and heavy. In addition, there is a problem that stable physical properties cannot be obtained due to individual differences peculiar to natural fibers and differences in harvested places. Furthermore, in knitted fabrics, the yarn has a loop structure and does not contribute to the strength and elastic modulus. In woven fabrics, the warp and weft yarns cross each other up and down to form a flat surface. There was a problem of breaking below the strength of the fiber.

  The present invention has been made in view of the above circumstances, and is a fiber-reinforced thermosetting resin having a high strength and uniform physical properties, using a spun yarn using a plant-based natural fiber that is preferable from the viewpoint of recycling. A molded body is provided.

According to the present invention, the following inventions 1 to 4 are provided.
1. A fiber reinforced thermosetting resin molding reinforced with natural fibers, wherein the natural fibers are spun yarns made of plant natural fibers, and the spun yarns are aligned in at least one direction, A fiber-reinforced thermosetting resin molded body, which is integrally molded.
2. 2. The fiber-reinforced thermosetting resin molded article according to 1 above, wherein the spun yarn is made of hemp fibers.
3. 3. The fiber-reinforced thermosetting resin molded article according to any one of 1 and 2, wherein the spun yarn is made of jute fiber.
4). The spun yarns are aligned in a plurality of directions, and the aligned plurality of aligned yarns are stitched in the thickness direction by stitching yarns and formed into a multi-axis inserted warp knitted fabric. A fiber-reinforced thermoplastic resin molded article according to any one of the above.
5). The fiber reinforced thermosetting resin molded article according to any one of 1 to 4, wherein the thermosetting resin is a vinyl ester resin, an unsaturated polyester resin, an epoxy resin, or a phenol resin.

In the present invention, by twisting a plant-based natural fiber preferable from the viewpoint of recycling into a spun yarn, it can be handled as a continuous fiber, and the volume content (Vf) can be improved. For example, it can be easily obtained even when the volume content (Vf) is about 50%. Moreover, even if there are individual differences peculiar to natural fibers or differences in harvested places, stable physical properties can be obtained by mixing in the pre-spinning process, and there are no environmental problems. Furthermore, the spun yarn is aligned at least in one direction and is integrally formed with the thermosetting resin, so that the yarn does not bend at the intersection of the warp and weft as in the case of woven fabric, and has high strength. A reinforced thermosetting resin molding can be obtained.
Fiber reinforced thermosetting using a reinforced fiber base material that is a multi-axis insertion warp knitted base material that is a single base material by aligning spun yarns in one direction at each angle, and laminating them and warping them. The flexible resin molding is raised.

Hereinafter, the present invention will be described in detail.
In the present invention, a spun yarn obtained by spinning a plant-based natural fiber is used. Here, plant-based natural fibers are cotton, hemp, bamboo, kapok, and the like, and hemp is preferable as reinforcing performance. Specific examples of hemp include flax, ramie, kenaf, cannabis, jute, manila hemp, and sisal hemp, which are vein fibers. Particularly preferred are linen yarn, jute and ramie.

The hemp fibers are preferably formed into a fiber-reinforced thermosetting resin molded body having an equilibrium moisture content. This is because the strength can be maintained high.

In the present invention, a spun yarn obtained by spinning the plant-based natural fiber is used. A spun yarn is a yarn composed of fibers that are relatively short in length and are not themselves in the form of a yarn. For example, a string-like fiber of about 1.5 m such as cannabis or ramie. It is also possible to unwind or cut the fiber to make a relatively short fiber to be a spun yarn. By using a thread-like material in this way, the advantage of improved mechanical strength properties is manifested. The spinning process may be based on a conventionally known process. In general, “Fiber Handbook” 2nd edition (edited by Textile Society of Japan, published by Maruzen Co., Ltd., published on March 25, 1994), page 283 “2.2.2 Spinning yarn” The method described is used. By using a spun yarn, it can be handled as a continuous fiber.

  In the present invention, the spun yarn group may be in the form of a sheet or a lump, but the yarns are aligned in a plurality of directions, and the aligned plurality of arranged yarns are bound in the thickness direction by stitching yarns, and multiaxial insertion is performed. It is preferable to be formed into a warp knitted fabric. Thereby, a high-strength molded body having no angle dependency can be obtained. For example, a plurality of arranged yarns arranged in a sheet form are laminated in two or more layers while changing the directionality for each sheet, and bundled by stitching yarns to form a multiaxial laminated sheet, so-called It is also possible to obtain a fiber reinforced plastic having an excellent reinforcing effect in multiple directions.

  The thermosetting resin used in the present invention is not particularly limited, and examples thereof include vinyl ester resins, unsaturated polyester resins, epoxy resins, polyamide resins, and phenol resins. In particular, unsaturated polyester resins and epoxy resins excellent in fiber impregnation properties are preferably used.

The fiber-reinforced thermoplastic resin molded body can use a conventional known molding method, and examples thereof include a hand lay-up method, a matched die method, a prepreg method, and a filament winding method.

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

Example 1
First, a resin to which a curing agent is added is poured on a molding table having a release film, and the resin is uniformly stretched with a roller. Here, the multi-axis warp knitting substrate A (FIG. 1) produced using jute yarn (400 tex) is placed on the resin. The resin is poured onto the base material and stretched uniformly with a roller. Next, as shown in FIG. 2, a multiaxial warp knitted base material B formed so as to be symmetric with the multiaxial insert warp knitted base material is placed and the resin is poured. Further, the resin is uniformly impregnated with a roller, a release film is placed from above, and spacers with a target thickness are installed on both ends of the substrate. A metal flat plate is placed on the spacer and allowed to stand at room temperature for about 12 hours or longer to be cured. Next, after curing in a dryer at 100 ° C. for 2 hours, it is completely cured. Thus, a fiber-reinforced plastic plate having a desired thickness can be produced.
The base material used in this experiment was 150 g / m ² per layer at an angle of 90 ° / ± 30 ° using jute yarn (400 tex), and the basis weight was 450 g / m ² . Polyester fiber (75 denier) was used for the stitch yarn.
Unsaturated polyester (Showa High Polymer Co., Ltd., Rigolac 150HRBQTNW) was used as the thermosetting resin, and 55% methyl ethyl ketone peroxide (MEKPO) was mixed with the resin 100 at 1%. The thickness of the fiber reinforced plastic plate was about 1.5 mm, and the fiber volume content (Vf) of the obtained fiber reinforced plastic plate was about 30%.

The obtained fiber reinforced plastic plate was sufficiently deformed without deformation due to its own weight.

(Example 2)
First, a resin to which a curing agent is added is poured on a molding table with a release film, and the resin is uniformly stretched with a roller. A uniaxial warp knitted substrate (90 °) produced using jute yarn (170 tex) is placed on the resin. The resin is poured onto the base material and stretched uniformly with a roller. Next, the same uniaxial insertion warp knitting substrate as that at the beginning is further placed and the resin is poured. Further, the resin is uniformly impregnated with a roller, a release film is placed from above, and spacers with a target thickness are installed on both ends of the substrate. A metal flat plate is placed on the spacer, pressed, and allowed to stand at room temperature for about 12 hours or longer to be cured. Next, after curing in a dryer at 100 ° C. for 2 hours, it is completely cured. Thus, a fiber-reinforced plastic plate having a desired thickness can be produced.
The base material used in this experiment was a 90 ° angle using a jute yarn (170 tex) and a basis weight of 150 g / m ² , and six of them were laminated in the same direction. Polyester fiber (75 denier) was used for the stitch yarn.
The resin was unsaturated polyester (Showa High Polymer Co., Ltd., Rigolac 150HRBQTNW), and the curing agent was 55% methyl ethyl ketone peroxide (MEKPO) mixed with 1% resin 100. The target thickness of the fiber reinforced plastic plate was about 1.2 mm, and the fiber volume content (Vf) of the obtained fiber reinforced plastic plate was about 50%.

The obtained fiber reinforced plastic plate was sufficiently deformed without deformation due to its own weight.

(Comparative example)
There is a chopped strand mat as a form of reinforcing fiber of glass fiber reinforced plastic that is often used at present. This is a glass roving cut into a length of about 2 inches, assembled in a random direction, and formed into a sheet with an emulsion resin.
Here, two layers of a chopped strand mat having a basis weight of 450 g / m ² were laminated by a hand lay-up method to prepare an FRP plate.
The resin was unsaturated polyester (Showa High Polymer Co., Ltd., Rigolac 150HRBQTNW), and the curing agent was 55% methyl ethyl ketone peroxide (MEKPO) mixed with 1% resin 100. Note that the thickness of the fiber reinforced plastic plate was 1.0 mm, and the fiber volume content (Vf) of the obtained fiber reinforced plastic plate was about 30%.

The obtained fiber reinforced plastic plate was sufficiently deformed without deformation due to its own weight.

A strip-shaped plate having a length of 250 mm and a width of 25 mm was cut out from the fiber-reinforced plastic plates obtained in the above Examples and Comparative Examples along the fibers in the 90 ° direction. An aluminum tab having a thickness of 1 mm was bonded to a position 50 mm from both ends, and this was used as a tensile test piece. In the tensile test, a strain gauge was used to measure the amount of strain.

The measurement test is as follows.
[Tensile test]
The tensile test was conducted according to JIS K 7054: 1995 using an autograph (manufactured by Shimadzu Corporation: AG-5000B) at a test speed of 1 mm / min.
The test results are shown in Table 1.

Regarding the test results of the above examples, since the thermosetting resin has a relatively low viscosity, it was impregnated into the spun yarn, and each physical property value was stable by using the spun yarn. In addition, by using natural fibers as spun yarn, it is possible to improve the fiber content of the fiber reinforced plastic plate, and to exhibit performance equivalent to or better than the commonly used glass chopped strand mat FRP. Became possible.

  The fiber-reinforced thermosetting resin molded article using continuous yarn formed by spinning the plant-based natural fiber of the present invention is useful in various fields such as interior fiber-reinforced plastics for automobiles, airplanes, vehicles and the like.

Schematic configuration diagram of jute multi-axis insertion warp knitting base material Schematic showing the laminated state of the jute multi-axis insertion warp knitting substrate

Explanation of symbols

A, B: Multi-axis insertion warp knitting base material

Claims (5)

A fiber-reinforced thermosetting resin molded body reinforced with natural fibers,
The natural fiber is a spun yarn made of plant-based natural fiber,
The fiber-reinforced thermosetting resin molded article, wherein the spun yarn is aligned in at least one direction and is integrally formed with a thermosetting resin. The fiber-reinforced thermosetting resin molded article according to claim 1, wherein the spun yarn is made of hemp fibers. The fiber-reinforced thermosetting resin molded article according to claim 1, wherein the spun yarn is made of jute fiber.   The spun yarn is aligned in a plurality of directions, and the aligned plurality of aligned yarns are stitched in the thickness direction by stitching yarns, and are formed into a multi-axis inserted warp knitted fabric. 4. The fiber-reinforced thermoplastic resin molded article according to any one of 3 above. The fiber reinforced thermosetting resin molded article according to any one of claims 1 to 4, wherein the thermosetting resin is a vinyl ester resin, an unsaturated polyester resin, an epoxy resin, or a phenol resin.

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