JP2008265108A - Fiber-reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced plastic which shows a smooth surface without undermining the advantages such as productivity and lightening of the fiber-reinforced plastic. <P>SOLUTION: This fiber-reinforced plastic 10 comprises a reinforcing fiber fabric 20 formed of a bundle 21 of piled reinforcing fibers and an impregnation resin 30 therein. The surface layer part 11 of the fiber-reinforced plastic 10 is made up of reinforcing fibers 40 flexed to the spring-like resilient shape and the impregnation resin 30 therein. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fiber reinforced plastic in which a reinforcing fiber bundle is impregnated with a resin, and relates to a fiber reinforced plastic in which the surface of the fiber reinforced plastic is further smoothed.

  Conventionally, fiber reinforced plastics (FRP) made of reinforced fibers and matrix resin (resin) are lighter than metal materials and have higher mechanical strength and elastic modulus than plastics that do not contain reinforced fibers. Because of such properties, fiber reinforced plastics are used in many fields such as aircraft, automobiles, railway vehicles, and ships.

  Such a fiber reinforced plastic is manufactured by, for example, an RTM (resin transfer molding) method. In the manufacturing method, a reinforcing fiber fabric made of, for example, a reinforcing fiber bundle is placed in a cavity of a mold having a smooth molding surface, a heated resin is injected into the cavity, and the reinforcing fiber fabric is impregnated. The heated resin is cooled and then demolded to produce a fiber reinforced plastic.

  However, since the thermal expansion coefficient of the reinforcing fiber is smaller than that of the resin, the thermal shrinkage at the time of cooling is large in the portion of the fiber reinforced plastic having a high resin content. In particular, as shown in FIG. 4, when the reinforcing fiber bundle 71 is a reinforcing fiber fabric, the space 73 between the reinforcing fiber bundles 71 such as a lattice region of the weave has a low ratio of reinforcing fibers, and the resin 60 Since the content is high, the heat shrinkage is large compared to other parts. As a result, regular depressions 75a are generated on the surface 75 of the fiber reinforced plastic 70 in accordance with the texture or arrangement period of the reinforcing fiber bundle 71 due to resin sink marks. For this reason, even if the molding surface 80a for molding the surface 75a of the fiber reinforced plastic 70 of the mold 80 is smooth, the surface 75 of the fiber reinforced plastic 70 is not a smooth surface. 70 aesthetics could be spoiled. In such a case, even if the surface 75 of the fiber reinforced plastic 70 is coated, it is difficult to smooth the unevenness of the surface of the fiber reinforced plastic 70. Therefore, in order to obtain the fiber reinforced plastic 70 having design properties, it is necessary to polish the uneven surface 75, which is a factor of reducing the productivity of the fiber reinforced plastic 70.

  In view of such a problem, for example, a method of manufacturing a fiber reinforced plastic using a gel coat has been proposed (for example, see Patent Document 1). Specifically, in this method, a liquid resin composition (gel coat) is applied to a smooth surface of a mold so as to have a predetermined thickness and cured to form a resin layer. Manufacture. Thus, by forming the resin layer by the gel coat on the surface of the fiber reinforced plastic, local dents between the reinforced fiber bundles are suppressed, and the surface of the fiber reinforced plastic becomes smooth.

  Further, as another method, for example, when a reinforcing fiber fabric made of reinforcing fiber bundles is arranged in a mold, powder such as calcium carbonate particles or alumina particles is formed on the surface of the reinforcing fiber fabric corresponding to the surface layer of the fiber reinforced plastic. A method of arranging (a so-called low shrinkage agent) has been proposed (see, for example, Patent Document 2). According to the method, since the powder can be arranged also in the space formed between the reinforcing fiber bundles, the resin content of the resin is reduced, thereby suppressing the shrinkage of the resin, and the local depressions in the lattice region. Can be suppressed.

  Furthermore, as another method, a method of arranging a nonwoven fabric such as glass fiber, carbon fiber, or organic fiber in a portion corresponding to the surface layer portion of the fiber reinforced plastic has been proposed. According to this method, since some fibers of the nonwoven fabric are also arranged in the space formed between the reinforcing fiber bundles, the shrinkage of the resin in the space is reduced, and the local dent on the surface of the fiber reinforced plastic is reduced. Can be reduced.

JP 2003-048263 A JP 2005-336218 A

  However, as described in Patent Document 1, when a fiber-reinforced plastic is produced by gel coating, it usually takes several tens of minutes to several hours to apply and cure the gel coating. As a result, compared to the method of polishing the surface of the fiber reinforced plastic and reducing the surface irregularities, there is almost no effect of shortening the molding time, and improving the productivity including the manufacturing cost of the fiber reinforced plastic Can not.

  Further, as described in Patent Document 2, in the method for producing fiber-reinforced plastic using powder, the specific gravity of the powder is 3.0 or more because the specific gravity of the powder is inorganic. Since such powder is larger than the fiber reinforced plastic having a specific gravity of about 1.5, the weight of the fiber reinforced plastic is increased, which impairs the essential advantage that the fiber reinforced plastic is lightweight. .

  Further, in the method of arranging fiber reinforced plastic using the nonwoven fabric, the reinforcing fibers of the nonwoven fabric are difficult to enter between the reinforcing fiber bundles, and the arrangement of the reinforcing fiber bundles is complicated (specifically, the shape of the reinforcing fiber fabric is complicated). In some cases, the nonwoven does not conform to its shape. Furthermore, when a nonwoven fabric made of organic fibers is used, the linear expansion coefficient is larger and softer than carbon fibers and glass fibers, so that resin shrinkage cannot be sufficiently suppressed.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to provide a fiber-reinforced plastic having a smooth surface without impairing the productivity and weight saving advantages of the fiber-reinforced plastic and the production thereof. It is to provide a method.

  In view of the above problems, the inventor has conducted intensive studies and as a result, in order to suppress the heat shrinkage of the resin in the space formed between the reinforcing fiber bundles in the vicinity of the surface, the thickness direction of the fiber reinforced plastic (the space It was considered effective to arrange the reinforcing fibers in the direction perpendicular to the surface of the reinforcing fiber bundles laminated in FIG. Therefore, the inventor, (1) when the mold is clamped, (1) the arranged reinforcing fibers are deformed along the surface of the mold and the surface of the laminated reinforcing fiber bundle (for example, reinforcing fiber fabric). It is important to satisfy the two requirements that reinforcing fibers are arranged in the space formed between the reinforcing fiber bundles and that they are not easily deformed by the heat shrinkage of the resin in this space. We obtained new knowledge that the above two requirements can be satisfied by using the reinforced fiber.

  The present invention is based on the above-mentioned new knowledge, and the fiber-reinforced plastic according to the present invention is a fiber-reinforced plastic obtained by impregnating a laminated reinforcing fiber bundle with a resin, and at least the surface layer portion of the fiber-reinforced plastic is Further, the resin is impregnated with a reinforcing fiber bent into a shape having a spring property.

  According to the present invention, the surface layer portion of the fiber reinforced plastic is impregnated with the resin in the reinforcing fiber bent into a shape having a spring property, so that the space formed between the reinforcing fiber bundles near the surface of the fiber reinforced plastic. In addition, since the reinforcing fibers are arranged, the heat shrinkage of the resin in the space is reduced, and the surface of the fiber-reinforced plastic becomes smooth.

  When the fiber reinforced plastic according to the present invention is manufactured by a vacuum bag molding method, a pressure bag molding method, an RTM (resin transfer molding) method, etc. The resin is particularly suitable because it does not easily shrink.

  That is, since the reinforcing fibers arranged in the space formed between the reinforcing fiber bundles are bent into a shape having a spring property, they are compressed and deformed when the reinforcing fibers are arranged in the mold (when the mold is clamped). At the same time, the reinforcing fiber is urged so that a restoring force acts, and the reinforcing fiber is further difficult to compress and deform. On the other hand, the reinforcing fibers arranged in the vicinity of the reinforcing fiber bundle in contact with the mold are compressed and deformed along the surface of the mold (surface forming the cavity) when the mold is clamped. When such a deformed reinforcing fiber is impregnated with a resin, in the surface layer portion of the fiber reinforced plastic, the thermal contraction of the resin in the space formed between the reinforcing fiber bundles is suppressed, and the reinforcing contact with the mold Since the reinforcing fibers arranged in the vicinity of the fiber bundle are compressed and deformed along the surface of the mold, it can be a fiber-reinforced plastic having a smooth surface.

  The “laminated reinforcing fiber bundle” according to the present invention refers to a reinforcing fiber bundle in which reinforcing fiber bundles in which fibers are bundled are laminated. For example, a reinforcing fiber bundle in which reinforcing fiber bundles are randomly laminated, or reinforcing in bundles of fibers. Examples include reinforced fiber woven fabrics in which fiber bundles are woven, and laminates of reinforced fiber fabrics, and are particularly limited as long as the reinforced fiber bundles are uniformly dispersed in fiber reinforced plastics. is not.

  The “reinforcing fiber bent into a spring-like shape” according to the present invention is deformed when a load acts on the reinforcing fiber, and is restored to its original shape when the load is unloaded. A fiber bent into an energizable shape, including a reinforcing fiber bent into a wave shape, a reinforcing fiber bent into a curl shape, a reinforcing fiber bent into a loop shape, a reinforcing fiber bent into a coil shape, and the like. May be a cloth-like fiber (non-woven fiber) as long as it is bent into the above-mentioned shape.

  More preferably, in the fiber reinforced plastic according to the present invention, it is more preferable that the reinforcing fiber bent into a shape having spring property is a reinforcing fiber bent into a coil shape. According to the present invention, the reinforcing fiber bent in a coil shape can be deformed simultaneously in at least three different directions of the three-dimensional space, so that the reinforcing fiber bent in the coil shape is formed in the space formed between the reinforcing fiber bundles. When the reinforcing fiber bundle is arranged, the reinforcing fiber can be deformed in a direction perpendicular to a surface on which the reinforcing fiber bundle is arranged (a surface formed by the woven fabric when the reinforcing fiber bundle is a reinforcing fiber woven fabric). As a result, it is possible to arrange reinforcing fibers also in the thickness direction of the surface layer of the fiber reinforced plastic. In this way, the thermal shrinkage of the resin in the space is reduced and the surface of the fiber reinforced plastic is smoothed.

  In the fiber-reinforced plastic according to the present invention, it is more preferable that the reinforcing fiber bundle is a reinforcing fiber fabric, and the curvature radius of the bent reinforcing fiber is at least 15 μm or more. According to the present invention, the space in the vicinity of the surface between the reinforcing fiber bundles of a general reinforcing fiber fabric (the groove or the recessed space in the lattice) is about 20 to 30 μm deep from the surface of the reinforcing fiber fabric. By setting the curvature radius of the bent reinforcing fiber to at least 15 μm or more, the reinforcing fiber can be secured up to the surface of the fiber reinforced plastic. That is, when the curvature radius of the bent reinforcing fiber is smaller than 15 μm, it is difficult to secure the reinforcing fiber arranged in the space up to the surface of the fiber reinforced plastic. The curvature radius of the bent reinforcing fiber is more preferably 1 mm or less. That is, in the case of a general reinforcing fiber fabric, the reinforcing fiber bundles are generally arranged at intervals of 2 mm. Therefore, when the radius of curvature is larger than 1 mm, the space near the surface of the fiber reinforced plastic is used. It becomes difficult to arrange the reinforcing fiber inside.

  When the reinforcing fiber bundle constituting the fiber reinforced plastic is a reinforcing fiber woven fabric, the weaving method may be a woven structure such as plain weave, twill weave, satin weaving, and the reinforcing fibers are unidirectional. It may be a so-called multiaxial fiber structure in which a plurality of aligned layers are cross-laminated so that the fiber axes of adjacent layers are shifted by about 30 ° to 90 °.

  Furthermore, examples of the reinforcing fiber related to the fiber-reinforced plastic according to the present invention include glass fiber, carbon fiber, aramid fiber, alumina fiber, boron fiber, steel fiber, PBO fiber, or high-strength polyethylene fiber. The reinforcing fiber constituting the reinforcing fiber bundle such as a reinforcing fiber fabric and the reinforcing fiber bent into a shape having spring property may not be the same type of fiber.

  More preferably, in the fiber reinforced plastic according to the present invention, the reinforcing fiber bent into a shape having a spring property is a carbon fiber. According to the present invention, the carbon fiber has higher elasticity than other fibers (the spring constant is high when coiled), and the restoring force is increased by slight deformation at the time of clamping. It is difficult to deform due to heat shrinkage.

  Examples of the carbon fibers include pitch-based carbon fibers made from petroleum and coal pitch, and PAN-based carbon fibers obtained by baking and graphitizing organic fibers made from polyacrylonitrile (PAN). . More preferably, the carbon fiber according to the present invention is a pitch-based carbon fiber. According to the present invention, since pitches such as coal and petroleum are used as raw materials, the carbon content in the spun fiber is as high as about 95% and the yield is as high as 85% compared to PAN-based carbon fibers. A higher elastic modulus can be obtained. As a result, the fiber shape can be maintained even against heat shrinkage of the resin.

  Further, the fiber reinforced plastic resin according to the present invention may be either a thermosetting resin or a thermoplastic resin. Examples of the thermosetting resin include an epoxy resin, a phenol resin, a melamine resin, and a urea resin. And resins such as silicone resin, maleimide resin, vinyl ester resin, unsaturated polyester resin, cyanate resin, or polyimide resin. Examples of the thermoplastic resin include nylon polyamide resins, polyester resins, polycarbonate resins, polyamideimide resins, and polyolefin resins.

  More preferably, in the fiber reinforced plastic according to the present invention, when the reinforcing fiber bundle and the bent reinforcing fiber are carbon fibers, the resin is preferably an epoxy resin. According to the present invention, carbon fiber reinforced plastic (CFRP) made of epoxy resin and carbon fiber can be lighter than other resin and fiber combinations. Furthermore, carbon fibers are superior in specific strength and specific rigidity compared to other fibers, and are compatible with epoxy resins, so that high-performance fiber-reinforced plastics can be obtained.

  As the present invention, a method for producing the fiber reinforced plastic is also disclosed. A method for producing a fiber reinforced plastic according to the present invention is a method for producing a reinforced fiber plastic in which a laminated reinforced fiber bundle is impregnated with a resin, wherein the reinforced fiber bundle is disposed in a mold. And a step of arranging reinforcing fibers bent into a spring-like shape on the surface of the reinforcing fiber bundle constituting at least the surface layer portion of the fiber reinforced plastic of the reinforcing fiber bundle, and a resin heated in the mold It is characterized by including at least a step of impregnating the reinforcing fiber bundle and the reinforcing fiber bent into a shape having a spring property with a heating resin, and a step of cooling the impregnated heating resin.

  According to the present invention, in the arranging step, the reinforcing fibers bent into a shape having a spring property are arranged on the surface of the reinforcing fiber bundle constituting the surface layer portion of the fiber reinforced plastic after the resin impregnation in the arranging fiber bundle. Thus, in the vicinity of the reinforcing fiber bundle in contact with the mold, the reinforcing fibers are deformed along the surface of the mold (surface forming the cavity) when the mold is clamped. Further, in the space between the fiber bundles of the reinforcing fiber fabric corresponding to the surface layer portion of the fiber reinforced plastic, the reinforcing fiber is compressed and deformed, and the reinforcing fiber is urged so that a restoring force acts. Difficult to deform due to heat shrinkage of resin in the space (the shape of the reinforcing fiber is easily maintained). As a result, even when the heated resin is impregnated into the reinforcing fiber and cooled, the resin in the space formed between the reinforcing fiber bundles is suppressed from thermal shrinkage, and in the vicinity of the reinforcing fiber bundle contacting the mold. Since the arranged reinforcing fibers are compressed and deformed along the surface of the mold, a fiber-reinforced plastic having a smooth surface can be produced.

  Further, in the method for producing a fiber reinforced plastic according to the present invention, it is more preferable to use a reinforcing fiber bent in a coil shape as the reinforcing fiber bent into a shape having a spring property, and the reinforcing fiber bundle is a reinforcing fiber fabric. More preferably, a reinforcing fiber having a curvature radius of the bent reinforcing fiber of at least 15 μm or more is used.

  Furthermore, it is preferable to use a carbon fiber as the reinforcing fiber bent into the shape having the spring property, and it is more preferable that the carbon fiber is a pitch-based carbon fiber. Furthermore, when carbon fiber is used as the reinforcing fiber, it is more preferable to use an epoxy resin as the resin. In the method for producing fiber-reinforced plastic according to the present invention, when a thermosetting resin such as an epoxy resin is used, the heating resin is an uncured thermosetting resin, and after impregnating the heating resin, More preferably, the heating resin is further heated and cured to a temperature equal to or higher than the temperature at which the resin is thermally cured before the cooling step.

  According to the present invention, a fiber reinforced plastic having a smooth surface and excellent design can be obtained without impairing the productivity and weight saving advantages of the fiber reinforced plastic.

  Hereinafter, an embodiment of a fiber reinforced plastic according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a fiber reinforced plastic according to the present embodiment, and FIG. 2 is a schematic view of a reinforced fiber bent into a spring-like shape disposed on the surface layer portion of the fiber reinforced plastic. .

  As shown in FIG. 1, the fiber reinforced plastic 10 according to the present embodiment is a fiber reinforced plastic obtained by impregnating an epoxy resin as a resin 30 into a reinforced fiber fabric 20 composed of a reinforced fiber bundle 21 made of carbon fibers. The carbon fibers constituting the reinforcing fiber bundle 21 are PAN-based carbon fibers obtained by firing polyacrylonitrile (PAN), and have a diameter in the range of 1 to 10 μm. The reinforcing fiber bundle 21 is a bundle of about 3000 to 24,000 carbon fibers, and the reinforcing fiber fabric 20 is woven using the reinforcing fiber bundle 21. The reinforcing fiber fabric 20 shown in FIG. 1 is a so-called multiaxial fiber structure fabric in which a plurality of layers in which reinforcing fiber bundles are aligned in one direction are cross-laminated so that the fiber axes of adjacent layers are shifted by about 90 °. However, it may be a woven structure such as plain weave, twill weave or satin weave.

  Further, the surface layer portion 11 of the fiber reinforced plastic 10 is impregnated with a resin 30 in a reinforcing fiber 40 bent in a coil shape (a reinforcing fiber bent in a shape having a spring property). As shown in FIG. 2, the reinforcing fiber 40 bent in a coil shape is a reinforcing fiber in which the reinforcing fiber is bent in a spiral shape, and is deformed when a load acts on the reinforcing fiber, and the load is unloaded. At that time, the original shape is restored. The reinforcing fiber 40 is made of pitch-based carbon fiber made from petroleum or coal pitch. The pitch-based carbon fiber has a higher elastic modulus (greater restoring force at the time of deformation) than a PAN-based carbon fiber generally used as a reinforcing fiber for fiber-reinforced plastics. Difficult to deform against shrinkage. Further, the radius of curvature of the reinforcing fiber 40 bent in a coil shape is at least 15 μm or more.

  A method for manufacturing the fiber reinforced plastic 10 will be described below with reference to FIG. FIG. 3 is a diagram for explaining a method of manufacturing the fiber reinforced plastic 10 shown in FIG. 1, and (a) is bent into a shape having a reinforcing fiber fabric 20 and a spring property in the mold 80. It is a figure for demonstrating the process of arrange | positioning the reinforced fiber 40, (b) is for demonstrating the process of impregnating the heated resin 30 to the reinforced fiber 20 and 40 arrange | positioned in the shaping | molding die 80 of (a). (C) is the figure which removed the fiber reinforced plastic 10 from the shaping | molding die after the process which cools the impregnated heating resin 30. FIG.

  First, as shown in FIG. 3A, a molding die 80 including an upper die 81 and a lower die 82 is prepared for molding fiber reinforced plastic. And the reinforcing fiber fabric 20 which consists of the reinforcing fiber bundle 21 comprised by carbon fiber in the lower mold | type 82 of the shaping | molding die 80, and the reinforcing fiber bundle which comprises the surface layer part of the fiber reinforced plastic 20 on the surface of this reinforcing fiber fabric 20 21) and the reinforcing fibers 40 bent in a coil shape are arranged, and the upper die 81 is pressed against the lower die 82 and clamped.

  At this time, as shown in FIG. 3 (b), the reinforcing fibers 40 arranged in the space 13 formed between the reinforcing fiber bundles 21 of the reinforcing fiber fabric 20 near the surface are bent into a shape having a spring property. Therefore, it is compressed and deformed when the mold is clamped, and is urged so that a restoring force acts, and the reinforcing fiber 40 becomes more difficult to compress and deform due to thermal contraction of the resin 30 described later. The reinforcing fiber 40 bent in a coil shape can be deformed simultaneously in at least three different directions of the three-dimensional space. For this reason, the reinforcing fiber 40 can be deformed also in the direction perpendicular to the plane formed by the reinforcing fiber fabric 20, and the reinforcing fiber 40 is also formed in the thickness direction of the surface layer portion of the fiber reinforced plastic against the thermal contraction of the resin described later. Becomes difficult to deform. Furthermore, while the depth of the recess formed by the reinforcing fiber bundles 21 of the reinforcing fiber fabric 20 is 20-30 μm, the radius of curvature of the reinforcing fiber 40 bent in a coil shape is as follows. Since the reinforcing fibers 40 are at least 15 μm or more, the reinforcing fibers 40 enter the gaps (valleys) between the reinforcing fiber bundles 21, and the reinforcing fibers 40 are secured also in the space 13 near the surface of the reinforcing fiber bundles 21 described above.

  On the other hand, the reinforcing fibers 40 arranged in the vicinity of the reinforcing fiber bundle 21 in contact with the molding die 80 are also reinforced fibers 40 in the space 13 along the surface of the molding die 80 (surface forming the cavity) during clamping. It compresses and deforms to a greater extent.

  And with respect to the reinforced fiber 40 and the reinforced fiber fabric 20 of such a deformation | transformation state, as shown in FIG.3 (b), from the resin inlet 81a of the upper mold | type 81, the heated uncured epoxy resin (heating resin) ) Is pressed into the mold, and the reinforcing fiber 40 and the reinforcing fiber fabric 20 are impregnated with the resin 30. Further, the fiber reinforced plastic 10 impregnated with the resin 30 is heated to a temperature equal to or higher than the thermosetting temperature of the resin 30 to cure the resin 30.

  Thereafter, as shown in FIG. 3C, the heated resin impregnated (cured) in the fiber reinforced plastic 10 is cooled, and the fiber reinforced plastic 10 is removed from the mold 80.

  In this way, in the arrangement step, as described above, the reinforcing fibers 40 in the vicinity of the reinforcing fiber bundle contacting the mold 80 are arranged by arranging the reinforcing fibers 40 bent in a coil shape on the surface of the reinforcing fiber fabric 20. Is deformed along the surface of the mold 80, and the reinforcing fibers 40 are hardly deformed in the space between the fiber bundles of the reinforcing fiber fabric 20. Therefore, the heated fibers 30 are impregnated into the reinforcing fibers 40 and cooled. However, the thermal contraction of the resin 30 in the space 13 formed between the reinforcing fiber bundles 21 of the reinforcing fiber fabric 20 is suppressed. As a result, the fiber reinforced plastic 10 having the smooth surface 15 can be obtained.

Hereinafter, examples according to the present embodiment will be described.
(Example)
<Reinforced fiber fabric>
Reinforcement of multiaxial fiber structure of 1000mm x 1000mm x thickness 2.5mm, in which 12,000 straight carbon fibers with a diameter of 7µm are bundled and reinforced fiber bundles with an outer diameter of 2mm are cross-laminated so as to be shifted by about 90 ° A fiber fabric was prepared and then cut into a predetermined size.
<Reinforcing fiber bent into a coil shape>
As reinforcing fibers bent in a coil shape, carbon fiber reinforcing fibers having a curvature radius of 40 to 70 μm and a coil length of 0.2 to 0.5 mm were prepared.
<Resin>
Epoxy resin (main material: EPICLON 840 (manufactured by Dainippon Ink and Chemicals)), curing agent: EPICLON B-570 (manufactured by Dainippon Ink and Chemicals), accelerator: 2E4MZ (manufactured by Shikoku Chemicals) )) Prepared.
<Molding>
A reinforcing fiber fabric and reinforcing fibers bent in a coil shape were disposed on the surface of the reinforcing fiber fabric in a mold in which a molding space of 360 mm × 300 mm × thickness 2 mm was formed. Next, an uncured epoxy resin heated to 60 ° C. was caused to flow into the mold at a pressure of 0.2 MPa, and the reinforcing fiber woven and the reinforcing fiber bent into a shape having a spring property were impregnated with the heating resin. Further, the uncured epoxy resin was heated to 150 ° C. to be cured, then cooled, and the fiber reinforced plastic was taken out from the mold. And the surface of the fiber reinforced plastic was observed, and based on JIS B0601, the filter waviness average value (micrometer) was measured. The results are shown in Table 1.

(Comparative example)
A fiber reinforced plastic was produced in the same manner as in the Examples. The difference from the example is that the reinforcing fiber bent in a coil shape was not arranged on the surface of the reinforcing fiber fabric. Then, the surface of the fiber reinforced plastic was observed in the same manner as in Example 1, and the average value of the waved waviness (μm) was measured.

(result)
The surface of the fiber reinforced plastic of the example had the same smooth surface as the surface of the mold, whereas the surface of the fiber reinforced plastic of the comparative example was close to the pitch of the reinforced fiber bundle of the reinforced fiber fabric. Regular irregular surfaces were formed.

(Evaluation)
In the comparative example, the space between the reinforcing fiber bundles of the reinforcing fiber fabric in the vicinity of the surface has a low thermal fiber ratio and a high resin content, so that the heat shrinkage is larger than the other parts. It is considered that an uneven surface was formed on the surface of the fiber reinforced plastic due to the shrinkage. On the other hand, in the embodiment, in the vicinity of the reinforcing fiber bundle in contact with the forming die, the reinforcing fiber bent in a coil shape at the time of clamping is deformed along the surface of the forming die, and in the space between the fiber bundles of the reinforcing fiber fabric, the coil Since the reinforcing fiber bent in a shape is compressed and deformed and a restoring force acts, it is considered that a smooth surface is formed on the surface of the fiber reinforced plastic.

  Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention described in the claims. Design changes can be made.

  For example, in the present embodiment, a manufacturing method by the RTM (resin transfer molding) method in which a thermosetting resin is injected into a mold to manufacture a fiber reinforced plastic has been described. However, the surface layer portion of the fiber reinforced plastic has a spring property. If reinforcing fibers bent into a shape can be arranged, hand lay-up method, vacuum bag molding method, pressure bag molding method, autoclave method using prepreg, and RFI (resin film infusion) method It may be manufactured by a manufacturing method such as

  Further, in this embodiment, the reinforcing resin bent in a coil shape is disposed on the surface layer portions of both sides of the fiber reinforced plastic, but the reinforcement strengthened in a coil shape according to a portion where smoothness is required on only one surface. A resin may be arranged.

  The fiber-reinforced plastic according to the present invention is particularly suitable for structural members that require design properties while ensuring mechanical strength. Specific examples include motorcycles such as motorcycle frames and cowls, and automotive parts such as doors, bonnets, tailgates, side fenders, side panels, and fenders.

The typical sectional view of the fiber reinforced plastic concerning this embodiment. Schematic of the reinforced fiber bent in the shape which has the spring property arrange | positioned at the surface layer part of fiber reinforced plastics. It is a figure for demonstrating the manufacturing method of the fiber reinforced plastic shown in FIG. 1, (a) demonstrates the process of arrange | positioning the reinforced fiber fabric and the reinforcement fiber bent in the shape which has a spring property in a shaping | molding die. (B) is a figure for demonstrating the process of impregnating the heated resin to the reinforced fiber arrange | positioned in the shaping | molding die of (a), (c) is a figure for cooling the impregnated heating resin The figure which removed the fiber reinforced plastic from the shaping | molding die after the process to do. Sectional drawing of the fiber reinforced plastic which concerns on this embodiment.

Explanation of symbols

  10: Fiber reinforced plastic, 11: Surface layer part, 15: Surface of fiber reinforced plastic, 20: Reinforced fiber fabric, 21: Reinforced fiber bundle, 40: Reinforced fiber bent into a coil shape (reinforced bent into a spring-like shape) Fiber), 30: Resin (epoxy resin)

Claims (6)

It is a fiber reinforced plastic impregnated with resin in a bundle of laminated reinforcing fibers,
At least a surface layer portion of the fiber reinforced plastic is impregnated with resin in a reinforced fiber bent into a shape having a spring property.   2. The fiber-reinforced plastic according to claim 1, wherein the reinforcing fiber bent into a shape having a spring property is a reinforcing fiber bent into a coil shape.   The fiber-reinforced plastic according to claim 1 or 2, wherein the reinforcing fiber bundle is a reinforcing fiber fabric, and a radius of curvature of the reinforcing fiber bent into a shape having a spring property is at least 15 µm or more.   The fiber-reinforced plastic according to any one of claims 1 to 3, wherein the reinforcing fiber bent into a shape having a spring property is a carbon fiber.   The fiber reinforced plastic according to claim 4, wherein the carbon fiber is a pitch-based carbon fiber. A method for producing a reinforcing fiber plastic in which a laminated reinforcing fiber bundle is impregnated with a resin,
The manufacturing method includes arranging reinforcing fiber bundles in a mold and reinforcing fibers bent into a shape having a spring property on the surface of reinforcing fiber bundles constituting at least a surface layer portion of the fiber reinforced plastic in the reinforcing fiber bundles. A step of arranging
Impregnating the reinforcing fibers bent into a shape having the reinforcing fiber bundle and the spring property by allowing the heated resin to flow into the molding die, and
And a step of cooling the impregnated heating resin.

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