JP2011236321A - Fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced plastic excellent in mechanical strengths, especially bending property.SOLUTION: The fiber-reinforced plastic is one comprising a reinforcing material constituted of fibers and a matrix resin. The reinforcing material constituted of fibers comprises a reinforcing material constituted of natural fibers and a reinforcing material constituted of glass fibers. In the reinforcing material constituted of fibers, the reinforcing material constituted of glass fibers, the reinforcing material constituted of natural fibers and the reinforcing material constituted of glass fibers are arranged in this order in the thickness direction of the fiber-reinforced plastic, in the matrix resin.

Description

  The present invention relates to a fiber reinforced plastic, particularly a fiber reinforced plastic containing natural fiber as a reinforcing material.

  Plastic is used for the interior of automobiles, airplanes, vehicles, etc., and is lighter than metal. However, since the strength is insufficient only with plastic, as a countermeasure, a fiber reinforced plastic whose strength is improved by including fibers as a reinforcing material has been proposed.

  In fiber reinforced plastics, glass fibers with good strength and light weight are often used as reinforcing materials (Patent Document 1). Recently, fiber reinforced plastics using natural fibers as reinforcing materials have also been proposed (Patent Documents 2 to 3).

JP-A-6-198792 JP 2004-143401 A JP 2004-149930 A

  However, when natural fibers are used as the reinforcing material, there is a problem that the mechanical strength is reduced as compared with the case where glass fibers are used as the reinforcing material.

  In order to solve the above-mentioned conventional problems, the present invention provides a fiber reinforced plastic excellent in mechanical strength, particularly in bending properties.

  The fiber reinforced plastic of the present invention is a fiber reinforced plastic containing a reinforcing material composed of fibers and a matrix resin, and the reinforcing material composed of the fibers is composed of a reinforcing material composed of natural fibers and glass fiber. The reinforcing material composed of the above-mentioned fibers includes the reinforcing material composed, and the reinforcing material composed of the glass fiber and the natural fiber in the matrix resin in the thickness direction of the fiber-reinforced plastic. It arrange | positions in order of the reinforcing material comprised with a material and glass fiber, It is characterized by the above-mentioned.

  The fiber reinforced plastic of the present invention is composed of a matrix resin and a reinforcing material composed of glass fibers, a reinforcing material composed of natural fibers, and glass fibers in the matrix resin in the thickness direction of the fiber reinforced plastic. By including a reinforcing material composed of fibers arranged in the order of the reinforcing materials to be provided, it is possible to have good mechanical strength.

FIG. 1 is a schematic cross-sectional view of a fiber reinforced plastic in one embodiment of the present invention. FIG. 2 is a perspective view of an interdigital sheet which is an example of a reinforcing material composed of natural fibers in the present invention. FIG. 3 is a conceptual perspective view of a multi-axis inserted warp knitting which is another example of the reinforcing material composed of natural fibers in the present invention.

  Hereinafter, the fiber-reinforced plastic of the present invention will be specifically described with reference to the drawings.

  As shown in FIG. 1, the fiber reinforced plastic 10 of the present invention includes a matrix resin 3 and a reinforcing material 1a made of glass fiber in the matrix resin 3 in the thickness direction of the fiber reinforced plastic. A reinforcing material composed of fibers positioned in the order of a reinforcing material 2 composed of fibers and a reinforcing material 1b composed of glass fibers (hereinafter also simply referred to as a reinforcing material) is included.

  The matrix resin is not particularly limited as long as it is a resin used for fiber-reinforced plastics. For example, a thermosetting resin or a thermoplastic resin can be used. Examples of the thermosetting resin include unsaturated polyester resins, epoxy acrylate resins, diallyl phthalate resins, epoxy resins, phenol resins, and melamine resins. Examples of the thermoplastic resin include saturated polyester resins such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate and polybutylene terephthalate, polyamide (nylon), polyacetal, and polycarbonate. Moreover, when using a thermosetting resin, you may use the resin composition which added the hardening | curing agent and the hardening accelerator to resin.

The glass fiber is not particularly limited as long as it is used for fiber reinforced plastic. The form of the glass fiber reinforcing material is not particularly limited. For example, a chopped strand mat, a nonwoven fabric, a woven fabric, a knitted fabric, a multi-axis inserted warp knitted fabric, or the like can be used. You may use it in combination with a glass fiber material. Among them, it is preferable to use a glass chopped strand mat from the viewpoints of availability and productivity. The glass chopped strand mat is not particularly limited in thickness and basis weight, but the thickness is preferably 0.1 to 3 mm, and the basis weight (mass per unit area) is 200 to 800 g / m ^2. It is preferable that Moreover, it is preferable that the single fiber diameter of glass fiber is 8-25 micrometers.

  It does not specifically limit as said natural fiber, It is preferable to use a plant-type natural fiber. Examples of plant-based natural fibers include cotton fibers, hemp fibers, bamboo fibers, and kapok fibers. Among these, hemp fibers are preferred from the viewpoint that the content of crystalline and strong cellulose is high. Examples of the hemp fibers include linen fiber, ramie fiber, jute fiber, cannabis fiber, kenaf fiber, and Manila hemp fiber. Among these, hemp fibers are preferable from the viewpoint of improving the flexural modulus, and one or more fibers selected from the group consisting of ramie fibers, jute fibers and kenaf fibers are more preferable.

  The form of the natural fiber reinforcing material is not particularly limited, but is preferably an interdigital sheet or a multiaxially inserted fiber sheet from the viewpoint of high fiber orientation. In the present invention, the interdigital sheet refers to a sheet in which natural fiber yarns arranged in one layer in one direction are connected by stitch yarns or a thermoplastic resin film. In addition, a multiaxially inserted fiber sheet is a sheet of natural fiber yarns arranged in one direction, arranged in two or more layers so that the directions of natural fibers in each layer are different, and connected by stitch yarns or thermoplastic resin films The sheet that is being used. In the above description, in the case of an interdigital sheet, a plurality of natural fiber yarns are aligned to form a sheet shape, but the plurality of natural fiber yarns are retained so as not to fall apart. In addition, in the case of a multiaxially inserted fiber sheet, in addition to the interdigital sheet, it also has the meaning of retaining the shape so that the layers do not fall apart.

  FIG. 2 is a perspective view of an interdigital sheet which is an example of a natural fiber reinforcing material in the present invention. The interdigital sheet 20 is composed of natural fiber yarns 21 arranged in one direction and stitch yarns 22 connecting the natural fiber yarns. Since the natural fiber yarns 21 are arranged in one direction, the strength of the fiber yarns in the arrangement direction is higher than that of woven fabrics and knitted fabrics. The interdigital sheet 20 may be used in one layer or in multiple layers. When used in multiple layers, it is preferable to align the natural fiber yarns 21 in multiple directions, that is, to balance the strength in each layer.

  FIG. 3 is a conceptual perspective view of a multiaxial insertion fiber sheet which is another example of the natural fiber reinforcing material in the present invention. In the multi-axis insertion fiber sheet 30, natural fiber yarns 31 arranged in a −30 ° direction, natural fiber yarns 32 arranged in a 30 ° direction, and natural fiber yarns 33 arranged in a 90 ° direction are: The stitch yarns 36 and 37 hung on the knitting needle 34 are stitched (bundled) in the thickness direction and integrated. This is a so-called multi-axis insertion warp knitting. The multi-axis inserted warp knitted fabric 30 can obtain a fiber reinforced plastic having an excellent reinforcing effect in multiple directions. Instead of or in combination with the stitch yarns 36 and 37, a binder such as a heat fusion yarn or a hot melt film may be used.

The natural fiber reinforcement is not limited particularly the basis weight and thickness, about 30~300g / m ² per layer, preferably about 60~800g / m ² as a whole reinforcement. Further, the thickness is preferably about 0.1 to 0.5 mm per layer, and the whole reinforcing material is preferably about 0.2 to 2 mm.

  The stitch yarn (sewing yarn, knitting yarn) is not particularly limited, and polypropylene yarn, polyethylene yarn, polyester yarn and the like can be used.

  In the fiber reinforced plastic, from the viewpoint of improving mechanical strength, the total volume content of the reinforcing material composed of fibers with respect to the fiber reinforced plastic is preferably 10 to 70%, and preferably 20 to 60%. Is more preferable. Moreover, it is preferable that the total mass content of the reinforcing material comprised with the fiber with respect to a fiber reinforced plastic is 15 to 90%, and it is more preferable that it is 30 to 80%.

  Moreover, in the said fiber reinforced plastic, from a viewpoint of improving mechanical strength, it is preferable that the volume content rate of the natural fiber reinforcement with respect to a fiber reinforced plastic is 5-65%, and it is more preferable that it is 15-50%. preferable. Further, the mass content of the natural fiber reinforcing material relative to the fiber reinforced plastic is preferably 5 to 70%, and more preferably 15 to 60%.

  The fiber-reinforced plastic of the present invention is obtained, for example, as follows when a thermosetting resin is used as the matrix resin. First, a reinforcing material composed of glass fibers is impregnated with a resin composition containing a matrix resin (hereinafter, simply referred to as a resin composition), and then a natural fiber reinforcing material is disposed on the resin composition. After impregnating with, a glass fiber reinforcing material is disposed thereon and impregnated with the resin composition. Next, a fiber reinforced plastic can be produced by thermosetting with a press machine and then after-curing with a dryer. The temperature of the press machine may be appropriately selected depending on the type of matrix resin to be used. Moreover, it is preferable to perform the thermosetting in a press with a pressure of 0.1-10 MPa and 0.1-5 hours. Further, the impregnation of the resin composition may be performed by a commonly used method, for example, by applying the resin composition to the surface of the reinforcing material with a roller and uniformly stretching it. In addition, there is no problem even if it is a method other than the above, for example, a hand lay-up method, a cold press method, an infusion molding method, an RTM molding method, or the like may be used.

  The fiber-reinforced plastic of the present invention is obtained, for example, as follows when a thermoplastic resin is used as the matrix resin. First, a reinforcing material made of glass fiber is sandwiched between two thermoplastic resin (eg, polyethylene resin, polypropylene resin, etc.) films. Similarly, a natural fiber reinforcing material is sandwiched between two thermoplastic resin (eg, polyethylene resin, polypropylene resin, etc.) films. Then, a material comprising a reinforcing material composed of glass fiber (with double-sided film) / natural fiber reinforcing material (with double-sided film) / a reinforcing material composed of glass fiber (with double-sided film) was melted by hot pressing. It is intended to be integrated.

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

<Manufacturing example of multi-axis inserted warp knitting A>
A 143-tex (tex) ramie yarn was further arranged so that the insertion angle was 90 ° C., the number of insertions was 30 / inch, and the basis weight was 168.9 g / m ² . Further, 143 tex ramie yarns were further arranged so that the insertion angle was 30 ° C., the number of insertions was 15 / inch, and the basis weight was 168.9 g / m ² . Further thereon, 143 tex ramie yarn was further arranged so that the insertion angle was −30 ° C., the number of insertions was 15 / inch, and the basis weight was 168.9 g / m ² . Finally, 8.3 tex polyester yarn is used as stitch yarn, stitched (bundled) in the thickness direction at a number of insertions of 250 / inch, integrated, and the basis weight is 513.1 g / m ² , thickness 1.3 mm A multi-axis inserted warp knitting A was obtained.

<Manufacturing example of multi-axis inserted warp knitting B>
143 tex ramie yarns were further arranged so that the insertion angle was 90 ° C., the number of insertions was 30 / inch, and the basis weight was 168.9 g / m ² . On top of that, 143 tex ramie yarns were further arranged so that the insertion angle was −30 ° C., the number of insertions was 15 / inch, and the basis weight was 168.9 g / m ² . Further thereon, 143 tex ramie yarn was further arranged so that the insertion angle was 30 ° C., the number of insertions was 15 / inch, and the basis weight was 168.9 g / m ² . Finally, 8.3 tex polyester yarn is used as stitch yarn, stitched (bundled) in the thickness direction at a number of insertions of 250 / inch, integrated, and the basis weight is 513.1 g / m ² , thickness 1.3 mm A multi-axis inserted warp knitted fabric B was obtained.

(Resin composition)
100 parts by weight of an epoxy resin (“Epicoat” 828 made by Japan Epoxy Range), 80 parts by weight of a curing agent (“Epicure” YH300 made by Japan Epoxy Range), and a curing accelerator (“Epicure” EMI24 made by Japan Epoxy Range) 1 part by weight was mixed to obtain a thermosetting resin composition.

Example 1
First, a release film was drawn on a stainless steel flat plate (thickness 2 mm). Next, the resin composition obtained above was poured onto the release film, and uniformly stretched with a roller. Next, a glass chopped strand mat (“MC450A” manufactured by Nittobo Co., Ltd., basis weight 450 g / m ² , thickness 0.9 mm, hereinafter referred to as GCM) is placed on the resin, and the resin composition obtained above is used. Sink and evenly stretch with a roller. Next, a multi-axis inserted warp knitted fabric A was placed on the resin, and the resin composition obtained above was poured and uniformly stretched with a roller. Next, a multi-axis inserted warp knitted fabric B was placed on the resin, and the resin composition obtained above was poured and uniformly stretched with a roller. Next, GCM was placed on the resin, the resin composition obtained above was poured, and after uniformly extending with a roller, a release film was placed from above to obtain a laminate. Thereafter, spacers having a thickness of 2.5 mm were installed at both ends of the laminate, a metal flat plate was placed on the spacer, and a stainless steel flat plate (thickness 2 mm) was placed on the metal flat plate. Next, the laminate was set in a press machine set at 90 ° C. and cured at a pressure of 4 MPa for 3 hours, followed by after-curing in a dryer at 120 ° C. for 6 hours to completely cure the resin. Produced a 2.6 mm fiber reinforced plastic.

(Example 2)
A fiber-reinforced plastic of Example 2 was produced in the same manner as in Example 1 except that a spacer having a thickness of 2.0 mm was used.

(Example 3)
A fiber reinforced plastic of Example 3 was produced in the same manner as in Example 1 except that a spacer having a thickness of 1.5 mm was used.

(Comparative Example 1)
A fiber reinforced plastic having a thickness of 2.6 mm was produced in the same manner as in Example 1 except that the multi-axis inserted knitted fabric A, GCM, GCM, and multi-axial inserted knitted fabric B were laminated in this order.

(Comparative Example 2)
A fiber reinforced plastic having a thickness of 1.5 mm was produced in the same manner as in Example 1 except that three GCMs were laminated and a spacer having a thickness of 1.5 mm was used.

(Comparative Example 3)
A fiber reinforced plastic having a thickness of 2.6 mm was produced in the same manner as in Example 1 except that three GCMs were laminated.

(Comparative Example 4)
Multi-axis inserted warp knitting A and multi-axis inserted warp knitting B are laminated in this order, and a fiber reinforced fiber having a thickness of 1.5 mm is the same as in Example 1 except that a 1.5 mm spacer is used Plastic was produced.

  The tensile elastic modulus, tensile strength, bending elastic modulus and bending strength of the fiber reinforced plastics of Examples and Comparative Examples were measured as follows, and the results are shown in Table 1 below. Table 1 also shows the thicknesses of the fiber-reinforced plastics of Examples and Comparative Examples, the volume content (%) of the reinforcing fibers, and the mass content (%) of the reinforcing fibers.

(Tensile modulus and tensile strength)
According to JIS K 7054 (1995), using an autograph (“AG-IS” manufactured by Shimadzu Corporation), a tensile test was performed at a distance between grips of 100 mm and a test speed of 1 mm / min, and the tensile modulus and tensile strength were determined. It was measured.

(Bending elastic modulus and bending strength)
In accordance with JIS K 7017 (1999, three-point bending test), a bending test was performed at a test speed of 1 mm / min, and the flexural modulus and bending strength were measured.

  As can be seen from Table 1, with respect to the thickness direction of the fiber reinforced plastic, Examples 1 to 3 including the reinforcing material arranged in the order of the glass fiber reinforcing material, the natural fiber reinforcing material, and the glass fiber reinforcing material in the matrix resin. The fiber reinforced plastic is excellent in all of the tensile elastic modulus, tensile strength, bending elastic modulus and bending strength. Moreover, it turns out that a tensile elasticity modulus, a tensile strength, a bending elastic modulus, and bending strength improve more, so that the volume content rate of the reinforcing material comprised with a fiber is higher from the comparison of Examples 1-3.

  Further, from the comparison between Example 1 and Comparative Examples 1 and 4, when the total volume content of the reinforcing material composed of fibers in the fiber reinforced plastic is the same, the natural fiber reinforcing material is placed between the glass fiber reinforcing materials. The fiber reinforced plastic of Comparative Example 1 in which the fiber reinforced plastic of Example 1 arranged was placed between the fiber reinforced plastic of Comparative Example 4 using only the natural fiber reinforcement and the glass fiber reinforcement between the natural fiber reinforcements. It can be seen that it is superior to plastic in all of tensile strength, flexural modulus and flexural strength.

  Moreover, from the comparison between Example 1 and Comparative Example 2, when the total volume content of the reinforcing material composed of fibers in the fiber reinforced plastic is the same, than the fiber reinforced plastic of Comparative Example 2 using only the glass fiber reinforcing material, It can be seen that the fiber reinforced plastic of Example 1 in which the natural fiber reinforcing material is disposed between the glass fiber reinforcing materials is superior in bending elastic modulus and bending strength. Further, from the comparison between Example 1 and Comparative Example 3, when the thickness of the fiber reinforced plastic is the same, the natural fiber reinforcing material is made of the glass fiber reinforcing material from the fiber reinforced plastic of Comparative Example 3 using only the glass fiber reinforcing material. It can be seen that the fiber-reinforced plastic of Example 1 disposed therebetween is superior in all of the tensile elastic modulus, tensile strength, bending elastic modulus and bending strength.

  The fiber-reinforced plastic of the present invention is suitable for automobiles, vehicles, ship interior materials, house interior materials, and the like.

DESCRIPTION OF SYMBOLS 1a, 1b Glass fiber reinforcement 2 Natural fiber reinforcement 3 Matrix resin 10 Fiber reinforced plastic 20 Interdigital sheet 21, 31, 32, 33 Natural fiber yarn 22, 36, 37 Stitch yarn 30 Multi-axis insertion warp knitting 34 Knitting needle

Claims (6)

A fiber reinforced plastic containing a reinforcing material composed of fibers and a matrix resin,
The reinforcing material composed of the fibers includes a reinforcing material composed of natural fibers and a reinforcing material composed of glass fibers,
The reinforcing material composed of the fiber is composed of the reinforcing material composed of glass fiber, the reinforcing material composed of natural fiber, and the glass fiber in the matrix resin in the thickness direction of the fiber reinforced plastic. A fiber reinforced plastic characterized by being arranged in the order of reinforcements.   The fiber reinforced plastic according to claim 1, wherein the reinforcing material composed of the natural fibers is an interdigital sheet or a multiaxial insertion fiber sheet.   The fiber-reinforced plastic according to claim 1 or 2, wherein the natural fiber is one or more fibers selected from the group consisting of cotton fiber, hemp fiber, bamboo fiber, and kapok fiber.   The fiber reinforced plastic according to any one of claims 1 to 3, wherein a volume content of the reinforcing material in the fiber reinforced plastic is 10 to 70%.   The fiber reinforced plastic according to any one of claims 1 to 4, wherein in the fiber reinforced plastic, a volume content of a reinforcing material composed of the natural fiber is 5 to 65%.   The fiber reinforced plastic according to claim 1, wherein the matrix resin is a thermosetting resin.

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