JP2015080944A - Fiber-reinforced resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of a crack on the periphery of joining yarn of a fiber-reinforced resin with a three-dimensional fiber structure as a reinforcement material, even if inorganic substance system reinforced-fiber such as carbon fiber is used for the whole of the joining yarn and in-plane yarn of the three-dimensional fiber structure.SOLUTION: A fiber-reinforced resin 10 is a fiber-reinforced resin of forming a resin as a matrix, with a three-dimensional fiber structure 11 constituted by joining a laminate fiber layer 13 by yarn (z) in the thickness direction as the joining yarn arranged in the crossing direction with respective fiber layers 12, as the reinforcement material. The respective fiber layers 12 are respectively arranged with any of in-plane yarn 12a-12d so that the laminate fiber layer 13 becomes at least biaxial orientation. In the fiber-reinforced-resin 10, metal powder 18 exists only in a matrix resin 15 around the yarn (z) in the thickness direction.

Description

  The present invention relates to a fiber reinforced resin, and more specifically, a laminated fiber layer in which in-plane yarns are arranged so as to be at least biaxially oriented and bonded with bonding yarns arranged in a direction crossing each fiber layer. The present invention relates to a fiber reinforced resin using a three-dimensional fiber structure as a reinforcing material.

  Fiber reinforced resins are widely used as lightweight structural materials. As a reinforcing material for fiber reinforced resin, there is a three-dimensional fabric (three-dimensional fiber structure). A fiber reinforced resin using this three-dimensional woven fabric as a reinforcing material and a resin as a matrix is used as a structural member for aircraft, automobiles, ships, or general industrial equipment. This fiber reinforced resin is arranged in a direction intersecting with the reinforcing fibers (in-plane threads) arranged in the reference plane, unlike the fiber reinforced resin formed by impregnating and curing the reinforced fibers such as woven fabric and nonwoven fabric. A three-dimensional woven fabric having a binding yarn (out-of-plane direction yarn) is used as a reinforcing base material. Therefore, compared with fiber reinforced resin which does not have a binding yarn, although it has high out-of-plane strength, there is a quality problem that cracks are likely to occur around the binding yarn.

  In order to cope with this problem, a three-dimensional fiber reinforced resin composite material is proposed in which a resin is impregnated and cured in a three-dimensional fabric in which a plurality of layers of laminated in-plane yarns are stitched together with sewing threads made of organic fibers. (See Patent Document 1). As shown in FIG. 3, the three-dimensional fiber reinforced resin composite material of Patent Literature 1 includes a plurality of warp threads 51 and a plurality of weft yarns 52 and a plurality of plane yarns orthogonal to a reference plane of the in-plane yarns 53. It is composed of a plate-like three-dimensional woven fabric 56 and a matrix resin 57 formed from a binding thread (sewing thread) 54 and an ear thread 55 for fixing the binding thread 54. The binding yarn 54 has a thickness of 1000 denier or less.

  The three-dimensional fiber reinforced resin composite material of Patent Document 1 suppresses the generation of cracks around the sewing thread by using organic fibers instead of using inorganic reinforcing fibers such as carbon fibers and glass fibers as sewing threads.

JP 2007-152672 A

  In the method of Patent Document 1, it is essential to use an organic fiber as a binding thread (sewing thread) constituting the three-dimensional fiber structure. However, there is a desire to use inorganic reinforcing fibers such as carbon fibers for all of the in-plane yarns and the binding yarns constituting the three-dimensional fiber structure.

  The present invention has been made in view of the above problems, and its purpose is to use inorganic reinforcing fibers such as carbon fibers for all the binding yarns and in-plane yarns of the three-dimensional fiber structure, An object of the present invention is to provide a fiber reinforced resin capable of suppressing the occurrence of cracks around the binding yarn of a fiber reinforced resin using a three-dimensional fiber structure as a reinforcing material.

  The fiber reinforced resin that solves the above problems is configured by bonding laminated fiber layers in which in-plane yarns are arranged so as to be at least biaxially oriented, with bonding yarns arranged in a direction intersecting with each fiber layer. A fiber reinforced resin using a three-dimensional fiber structure as a reinforcing material and a resin as a matrix, and metal powder is present only in the matrix resin around the binding yarn. Here, the “in-plane yarn” and the “binding yarn” mean not only a yarn in which the fibers are twisted but also a fiber bundle in which the fibers are aligned without being twisted.

  According to this configuration, when a fiber reinforced resin is produced by curing the matrix resin in a state where the three-dimensional fiber structure is impregnated with an uncured matrix resin, the matrix resin is locally generated by performing induction heating. The matrix resin present around the binding yarn, which is a large part, is rapidly heated by the exothermic heat of the metal powder and hardens before the other part. Therefore, even if the shrinkage of the matrix resin around the metal powder occurs, the surrounding uncured matrix resin is replenished to the portion where the volume is reduced due to the shrinkage. As a result, even when carbon fibers with a very small volume change compared to the matrix resin are used as the binding yarn, the stress applied to the interface between the binding yarn with a small volume change and the matrix resin is reduced, and cracks around the binding yarn occur. Is suppressed. Accordingly, even if inorganic reinforcing fibers such as carbon fibers are used for all the binding yarns and in-plane yarns of the three-dimensional fiber structure, around the fiber-reinforced resin binding yarn using the three-dimensional fiber structure as a reinforcing material. Generation of cracks can be suppressed.

  The binding yarn is inserted into the laminated fiber layer from one surface in the thickness direction of the laminated fiber layer and is folded back by engaging with a retaining yarn arranged outside the other surface of the laminated fiber layer. The retaining yarns are arranged in a direction crossing the arrangement surface of the binding yarns, and the periphery of the binding yarns is the one side of the laminated fiber layer where the binding yarns are It is preferable that the portion is arranged in a bifurcated manner.

  When the binding yarn is inserted into the laminated fiber layer from one surface side and arranged so as to be folded back by engaging with a retaining yarn (so-called ear yarn) arranged outside the other surface, It is arranged in two forks on the surface side. Then, the portion (bifurcated portion) becomes a resin pool when impregnated with the resin, and the binding yarn is stressed in the direction in which the bifurcated portion expands, so that a crack is likely to occur when the matrix resin is cured and contracted. However, the presence of metal powder at the bifurcated portion suppresses the generation of cracks.

  The periphery of the binding yarn is preferably between the binding yarn and the adjacent in-plane yarn. There is a portion where the matrix resin locally increases between the binding yarn and the in-plane yarn where the binding yarn of the laminated fiber layer is inserted. Therefore, the occurrence of cracks is suppressed by the presence of the metal powder in that portion.

  According to the present invention, even when inorganic reinforcing fibers such as carbon fibers are used for all of the binding yarns and in-plane yarns of the three-dimensional fiber structure, the binding of the fiber reinforced resin using the three-dimensional fiber structure as a reinforcing material The occurrence of cracks around the yarn can be suppressed.

(A) is a schematic cross section of the fiber reinforced resin of one Embodiment, (b) is the elements on larger scale of (a). The schematic cross section of the fiber reinforced resin of another embodiment. The schematic cross section of a prior art.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIG.
As shown in FIG. 1A, the fiber reinforced resin 10 is a fiber reinforced resin using a three-dimensional fiber structure 11 as a reinforcing material and a resin as a matrix. The three-dimensional fiber structure 11 is a direction in which the fiber layers 12 in which the in-plane yarns 12a, 12b, 12c, and 12d are arranged are laminated and the laminated fiber layer 13 that is at least biaxially oriented intersects each fiber layer 12. Are joined by a thickness direction yarn z as a binding yarn arranged in a row. The fiber layer 12 is composed of, for example, a unidirectional sheet (UD sheet) in which carbon fiber bundles are aligned in one direction. The thickness direction thread z is composed of, for example, a carbon fiber bundle.

  The laminated fiber layer 13 is a fiber layer 12 composed of an in-plane thread 12a having an arrangement angle of 0 degrees, a fiber layer 12 composed of an in-plane thread 12b having an array angle of 90 degrees, and a fiber comprising an in-plane thread 12c having an array angle of 45 degrees. A predetermined number of layers 12 and fiber layers 12 made of in-plane threads 12d having an arrangement angle of −45 degrees are laminated to form a quasi-isotropic property. And the fiber layer 12 which consists of the in-plane thread | yarn 12c of 45 degrees of arrangement | sequence angles is arranged on both surfaces of the thickness direction of the lamination | stacking fiber layer 13, respectively. The in-plane threads 12a, 12b, 12c, and 12d are arranged in a plane orthogonal to the thickness direction of the three-dimensional fiber structure 11 (vertical direction in FIG. 1A). Each of the in-plane yarns 12a, 12b, 12c, and 12d is not a twisted yarn but a continuous fiber bundle in which the fibers are aligned without being twisted.

  The thickness direction thread z is inserted into the laminated fiber layer 13 from one surface in the thickness direction of the laminated fiber layer 13 and is engaged with a retaining thread 14 arranged outside the other surface of the laminated fiber layer 13. Thus, the portions arranged so as to be folded in a loop and the portions arranged along the other surface side of the laminated fiber layer 13 are alternately arranged.

  In the fiber reinforced resin 10, the matrix resin 15 exists not only inside the three-dimensional fiber structure 11 but also on the outer peripheral surface of the three-dimensional fiber structure 11. Therefore, the fiber reinforced resin 10 has a loop-shaped folded portion of the thickness direction yarn z between a portion in which the laminated fiber layer 13 protrudes from one surface in the thickness direction and a loop shape of the thickness direction yarn z. There is a resin reservoir 17 on the inner side of the folded portion and on the inner side of the bifurcated portion 16 of the root portion on the opposite side of the loop-shaped folded portion of the thickness direction thread z. In addition, there is a resin reservoir 17 in which the amount of resin is small in the interior of the three-dimensional fiber structure 11 as compared with the resin reservoir 17 existing outside, but the amount of resin is larger than that in other portions inside. There is a periphery of the thickness direction thread z extending in parallel as a position of the resin reservoir 17 existing inside the three-dimensional fiber structure 11.

  As shown in FIG. 1B, metal powder 18 adheres to the surface of the thickness direction thread z. Therefore, the metal powder 18 exists only in the part around the thickness direction yarn z in the matrix resin 15 constituting the fiber reinforced resin 10. Specifically, the thickness direction thread z is inserted in a folded manner into the bifurcated portion 16 where the thickness direction thread z is bifurcated on one side of the laminated fiber layer 13 and the thickness direction thread z. Around the thickness direction yarn z of the matrix resin 15 existing between the thickness direction yarn z of the portion extending in parallel and between the thickness direction yarn z extending in parallel and the adjacent in-plane yarn 12a and the like. Metal powder 18 is present. For example, iron powder is used as the metal powder 18. In addition, illustration of the metal powder 18 is abbreviate | omitted in Fig.1 (a). Further, in FIG. 1 (a), for convenience of illustration, the thickness direction thread z of the portion that is inserted into the laminated fiber layer 13 in a folded shape and extends in parallel is shown in a state of being completely adhered, Actually, a gap exists as shown in FIG.

  Next, an example of the manufacturing method of the fiber reinforced resin 10 comprised as mentioned above is demonstrated. In the three-dimensional fiber structure 11, the thickness direction yarn z is inserted into the laminated fiber layer 13 by a known method, for example, a method basically similar to the method disclosed in JP-A-8-218249. That is, in the thickness direction of the laminated fiber layer 13, a plurality of insertion needles in which the thickness direction thread z is hooked in the hole provided at the tip are inserted until the holes of each insertion needle penetrate the laminated fiber layer 13. Thereafter, each insertion needle is slightly retracted, and the retaining thread 14 is inserted into the portion where the thickness direction thread z is looped. In this state, the insertion needle is pulled back, and with the tension applied to the retaining thread 14, the retaining thread 14 is tightened by the thickness direction thread z to bond the fiber layers 12. Similarly, the insertion needle insertion operation, the retaining thread insertion operation, and the insertion needle retraction operation are similarly performed at the position where the insertion needle has been moved by a predetermined pitch.

  When tension is applied to the thickness direction thread z to pull back the looped portion, and the compression force is applied to the laminated fiber layer 13 by the retaining thread 14, the thickness direction thread z has roots arranged in a folded shape. A force is applied to the portion in the direction of expanding the interval between the two thickness direction threads z arranged in parallel with each other. Therefore, the interval between the root portions of the thickness direction yarn z is increased, and the interval between the portions of the thickness direction yarn z existing in parallel in the laminated fiber layer 13 is also slightly increased.

  The obtained three-dimensional fiber structure 11 is impregnated and cured with resin to produce a fiber reinforced resin 10. For resin impregnation and curing, for example, a resin transfer molding (RTM) method is employed. In the RTM method, in a state where the three-dimensional fiber structure 11 is arranged in a resin impregnation mold, a liquid thermosetting resin is injected into the mold, and is heated and cured to obtain the fiber reinforced resin 10. For example, an epoxy resin is used as the thermosetting resin.

  As a method for causing the metal powder 18 to exist around the thickness direction thread z at the location that becomes the resin reservoir 17, for example, when the fiber layers 12 of the laminated fiber layer 13 are bonded with the thickness direction thread z, the metal powder 18 is used. A three-dimensional fiber structure 11 is manufactured using the thickness direction thread z 18 attached to the surface. Examples of the thickness direction yarn z with the metal powder 18 adhered to the surface include, for example, those in which the metal powder 18 is directly sprinkled on the surface of the thickness direction yarn z, or the thickness direction impregnated with uncured resin. Thickness direction yarn z in which metal powder 18 is adhered to the surface of yarn z or impregnated with uncured resin in which metal powder 18 is dispersed is used. And after manufacturing the three-dimensional fiber structure 11, you may make the metal powder 18 adhere to the forked part 16 of the thickness direction thread | z.

  When the fiber reinforced resin 10 is produced by curing the matrix resin 15 in a state where the three-dimensional fiber structure 11 is impregnated with the uncured matrix resin 15, the metal powder 18 is obtained by performing induction heating in addition to normal heating. The matrix resin 15 existing around the metal powder 18 is rapidly heated and hardened before other portions. Therefore, the matrix resin 15 around the thickness direction thread z to which the metal powder 18 is attached is cured and contracted before the surrounding matrix resin 15. However, since the surrounding uncured matrix resin 15 maintains fluidity, no residual stress is generated in the cured portion. Further, since the resin curing is performed in a state where the matrix resin 15 is pressurized, even if the curing shrinkage of the matrix resin 15 around the metal powder 18 occurs before other portions, the volume tends to be reduced due to the shrinkage. The portion is replenished with surrounding uncured matrix resin 15. As a result, even when carbon fibers having a very small volume change compared to the matrix resin 15 are used as the thickness direction thread z, the stress applied to the interface between the thickness direction thread z having a small volume change and the matrix resin 15 is small. Thus, the occurrence of cracks at the interface between the thickness direction yarn z and the matrix resin 15 is suppressed.

  Curing shrinkage of the matrix resin 15 occurs in the high Vf portion inside the three-dimensional fiber structure 11, which is a portion other than the resin reservoir 17, that is, in a portion where the resin density is low. It becomes difficult to be overloaded.

According to this embodiment, the following effects can be obtained.
(1) The fiber reinforced resin 10 has a thickness in which the laminated fiber layers 13 in which the in-plane yarns 12a, 12b, 12c, and 12d are arranged so as to be at least biaxially oriented are arranged in a direction intersecting each fiber layer 12. It is a fiber reinforced resin in which a three-dimensional fiber structure 11 constituted by being bonded by a longitudinal thread z (binding yarn) is used as a reinforcing material and a resin is used as a matrix. The metal powder 18 exists only in the matrix resin 15 around the thickness direction thread z. When the fiber reinforced resin 10 is manufactured, by performing induction heating, the matrix resin 15 existing around the thickness direction yarn z, which is a portion where the matrix resin 15 is locally present, is generated due to the heat generated by the metal powder 18. Rapidly heated and hardened before other parts. Therefore, even if the curing shrinkage of the matrix resin 15 around the metal powder 18 occurs, the surrounding uncured resin is replenished to the portion whose volume is to be reduced by the shrinkage. As a result, even when a carbon fiber having a very small volume change compared to the matrix resin 15 is used as the thickness direction thread z, the stress applied to the interface between the thickness direction thread z and the matrix resin 15 having a small volume change is reduced. . Therefore, even if inorganic reinforcing fibers such as carbon fibers are used for the thickness direction yarn z and the in-plane yarns 12a, 12b, 12c, and 12d of the three-dimensional fiber structure 11, the three-dimensional fiber structure 11 is reinforced. The generation of cracks around the binding yarn of the fiber reinforced resin 10 used as a material can be suppressed.

  (2) The thickness direction yarn z as the binding yarn is inserted into the laminated fiber layer 13 from one surface in the thickness direction of the laminated fiber layer 13 and arranged outside the other surface of the laminated fiber layer 13. The retainer yarns 14 are arranged so as to be folded back by engaging with the retainer yarns 14, and the retainer yarns 14 are arranged in a direction crossing the arrangement surface of the thickness direction yarns z. Metal powder 18 exists in the bifurcated portion 16 of the thickness direction yarn z as the periphery of the binding yarn. The inner portion of the bifurcated portion 16 becomes a resin reservoir 17 when impregnated with the resin, and the thickness direction thread z is subjected to stress in the direction in which the bifurcated portion 16 expands. Become. However, when the fiber reinforced resin 10 is manufactured, the induction heating causes the metal powder 18 present in the bifurcated portion 16 of the thickness direction yarn z to generate heat, and the matrix resin 15 in the vicinity of the thickness direction yarn z becomes other. By rapid curing prior to this portion, occurrence of cracks in the bifurcated portion 16 is suppressed.

  (3) The metal powder 18 exists between the thickness direction thread z and the adjacent in-plane threads 12a, 12b, 12c, and 12d as the periphery of the binding thread. Between the thickness direction yarn z and the in-plane yarns 12a, 12b, 12c and 12d where the binding yarn (thickness direction yarn z) of the laminated fiber layer 13 is inserted, there is a lot of matrix resin 15 locally. There is a part. Therefore, the presence of the metal powder 18 in the portion suppresses the occurrence of cracks in the matrix resin 15 existing between the thickness direction yarn z and the in-plane yarn 12a and the like.

The embodiment is not limited to the above, and may be embodied as follows, for example.
As shown in FIG. 2, the binding yarn 20 is inserted from one surface in the thickness direction of the laminated fiber layer 13 toward the other surface, extends a predetermined distance along the outside of the other surface, and then the other It may be arranged so as to be repeatedly inserted from one surface toward one surface and extending a predetermined distance along the outside of the one surface. In this case, the retaining thread 14 is not necessary, and the bifurcated portion 16 of the thickness direction thread z is also eliminated. Therefore, compared to the case where the bifurcated portion 16 of the thickness direction thread z is present, the occurrence of cracks due to the resin reservoir 17 around the binding yarn 20 is less likely to occur.

The metal powder 18 is not limited to iron powder, but may be other metal powder.
○ As a method of causing the metal powder 18 to exist around the thickness direction thread z at the location that becomes the resin reservoir 17, after the three-dimensional fiber structure 11 is manufactured, the metal powder 18 is adhered to the portion of the thickness direction thread z. May be.

  The laminated fiber layer 13 is not limited to the one-way sheet, and may be a plain weave, for example. If the plain weaves are simply overlapped, the in-plane biaxially oriented laminated fiber layer 13 is obtained, and if the adjacent plain weaves are laminated so that the angle between the warp yarns is 45 degrees, the in-plane biaxially oriented laminated fiber layer 13 is obtained. It becomes.

O The thickness direction thread | z and the binding thread | yarn 20 may be the structure inserted in the laminated fiber layer 13 in the state inclined rather than the state orthogonal to the laminated fiber layer 13.
O The laminated fiber layer 13 constituting the three-dimensional fiber structure 11 is not limited to a laminate of a unidirectional sheet or a plain weave. For example, a flat braid or interlock fabric may be used, or a round (cylindrical) braid may be flatly crushed for use.

  ○ The lamination order of the in-plane yarns 12a to 12d constituting the laminated fiber layer 13 in a pseudo-isotropic and in-plane four-axis orientation is such that the outer layer is the in-plane yarn 12c (+45 degree layer) or the in-plane yarn 12d (−45 degrees). The order is not limited.

  As shown in FIG. 2, the quasi-isotropic and in-plane four-axis oriented laminated fiber layer 13 has a surface between the fiber layer 12 made of the in-plane yarn 12c and the fiber layer 12 made of the in-plane yarn 12d. You may arrange | position the fiber layer 12 which consists of an inner thread 12b.

  The laminated fiber layer 13 only needs to be at least biaxially oriented, and is not limited to in-plane tetraaxial orientation with pseudo-isotropic properties. For example, when the in-plane triaxial laminated fiber layer 13 is composed of yarns having an orientation angle of 0 degrees, 60 degrees, and −60 degrees, or the in-plane 4-axis laminated fiber layer 13 is formed, the orientation angle is The orientation angle of other in-plane aligned yarns of 0 degree and 90 degrees may be an orientation angle other than ± 45 °. Further, the laminated fiber layer 13 may be in-plane biaxial orientation with orientation angles of 0 degrees and 90 degrees.

  ○ The in-plane yarns 12a, 12b, 12c, 12d, the retaining yarn 14, the thickness direction yarn z, and the binding yarn 20 are not limited to fiber bundles that are arranged without being twisted, depending on the type of fiber. May be a yarn in which the fibers are twisted.

  ○ The fiber bundle constituting the three-dimensional fiber structure 11 is not limited to carbon fiber, for example, inorganic fiber such as glass fiber or ceramic fiber, or aramid fiber, poly-p-phenylenebenzobisoxazole fiber, polyarylate fiber, It may be a high-strength organic fiber such as ultrahigh molecular weight polyethylene fiber, and is appropriately selected according to the required performance. For example, when the required performance of rigidity and strength for the fiber reinforced composite material is high, carbon fiber is preferable.

  z: Thickness direction yarn as a binding yarn, 10 ... Fiber reinforced resin, 11 ... Three-dimensional fiber structure, 12 ... Fiber layer, 12a, 12b, 12c, 12d ... In-plane yarn, 13 ... Laminated fiber layer, 14 ... Retaining thread, 15 ... matrix resin, 18 ... metal powder, 20 ... bonding thread.

Claims (3)

  A reinforcing material is a three-dimensional fiber structure in which laminated fiber layers in which in-plane yarns are arranged so as to be at least biaxially oriented are bonded with bonding yarns arranged in a direction intersecting with each fiber layer, A fiber reinforced resin having a resin as a matrix, wherein the metal powder exists only in the matrix resin around the binding yarn.   The binding yarn is inserted into the laminated fiber layer from one surface in the thickness direction of the laminated fiber layer and is folded back by engaging with a retaining yarn arranged outside the other surface of the laminated fiber layer. The retaining yarns are arranged in a direction crossing the arrangement surface of the binding yarns, and the periphery of the binding yarns is the one side of the laminated fiber layer where the binding yarns are The fiber reinforced resin according to claim 1, wherein the fiber reinforced resin is a bifurcated portion.   The fiber-reinforced resin according to claim 1, wherein the periphery of the binding yarn is between the binding yarn and the adjacent in-plane yarn.