Mesh-shaped fiber-reinforced composite material, mesh-shaped knitted structure, material for forming mesh-shaped fiber-reinforced composite material, and formed body of mesh-shaped fiber-reinforced composite material

Abstract

Provided is a mesh-like fiber-reinforced composite material which is composed of a knitted base material that can withstand deep drawing during shaping, has superior stretchability and drape properties to those of the conventional materials, has excellent formability into a shape having a curved face and excellent air permeability, can be prevented from stuffiness, has a light weight and high strength, and has high stiffness and excellent impact resistance. Further provided are: a mesh-like knitted structure; a material for forming a mesh-like fiber-reinforced composite material; and a mesh-like fiber-reinforced composite material shaped body. The mesh-like fiber-reinforced composite material has a mesh-like knitted structure composed of the following three types of yarns: a plurality of rows of knitted structures (20) in each of which a chain stitch yarn (2) runs continuously in a loop-like shape in the lengthwise direction to form a knitted chain stich (2A); a plurality of rows of weft insert yarns (3) each of which is inserted while folding and shaking the lengthwise-direction knitted structures in at least three rows per course in the crosswise direction, and warp insert yarns (4) each of which is inserted in the direction of a plurality of rows produced by shaking the chain knitted yarn in one row per course in the opposite direction of the weft insert yarn. In the mesh-like fiber-reinforced composite material, only the knitted structures, the warp insert yarns and the weft insert yarns are impregnated with a resin and are cured. In the mesh-like fiber-reinforced composite material, each of the chain stitch yarns comprises (a) an organic fiber made from polyester, nylon, vinylon or the like, or (b) a high-strength fiber such as an aramid long fiber, a PBO long fiber, an ultra-high-molecular-weight polyethylene fiber and a high-strength polyarylate long fiber, or (c) an inorganic fiber such as a glass long fiber and a basalt fiber, and each of the warp and weft insert yarns comprises (a) an inorganic fiber such as a glass long fiber and a basalt fiber or (b) a high-strength fiber such as an aramid long fiber, a PBO long fiber, an ultra-high-molecular-weight polyethylene fiber and a high-strength polyarylate long fiber.

Description

Mesh-like fiber reinforced composite material, mesh-like knitted structure, material for molding mesh-like fiber reinforced composite material, and mesh-like fiber reinforced composite molded body

[0001] The present invention relates to a mesh-like fiber-reinforced composite material that is a composite material of a thermosetting or thermoplastic resin and reinforcing fibers, and that is suitable for use as a filter, cover, reinforcing member, and particularly as an interior / exterior member for protectors such as safety helmets and prosthetic limbs (artificial legs, artificial arms) because it is a mesh-like composite material with a high opening ratio, light weight, high strength, and high impact resistance. The present invention also relates to a mesh-like knitted structure and a mesh-like fiber-reinforced composite molding material used for the mesh-like fiber-reinforced composite material, and further to a mesh-like fiber-reinforced composite molded product obtained by shaping the mesh-like fiber-reinforced composite molding material.

[0002] Conventionally, most mesh materials have been made of resin or metal, but resin is lightweight but lacks strength, while metal is strong but heavy.

[0003] This problem is particularly significant in protective gear worn for body protection, and in recent years, fiber-reinforced plastic components have been used in some cases. For example, caps with inner linings have been proposed and are commercially available, and are worn by security guards, station staff, police officers, and others as uniform caps to protect the head from unexpected falling objects or external impacts, and can also be worn by children, the elderly, and the general public as sports caps to protect the head.

[0004] 7(a) and 7(b) attached to the present application, Patent Document 1 describes a hat 100 with a protective inner liner, which includes a cloth cap-shaped hat body (crown) 102 and a brim 103, and a protective inner liner 110 provided inside the hat body 102. As shown in the figure, the protective inner liner 110 is fitted to the inside of the hat body 102 and has a generally spherical, curved, bowl-like shape so that it can fit the person's head when worn, and is made of a fiber-reinforced plastic (FRP) and forms the basic structure of the inner liner. The inner liner 111 has a curved shape similar to the shape of the top region of the hat body 102, a cushion member 112 arranged inside the inner liner 111, and a cover sheet 113 arranged to cover the inner liner 111 and the cushion member 112.

[0005] The protective inner hat 100 described in the above-mentioned Patent Document 1 is lightweight and has good breathability, and is also excellent in impact resistance and comfort.

[0006] However, in the protective hat with inner liner 100 described in Patent Document 1, the inner body 111, which forms the basic structure of the inner liner, is made of a fiber-reinforced plastic (FRP) material obtained by impregnating unidirectional or woven reinforced fibers with a matrix resin such as a thermosetting resin or a thermoplastic resin and then curing the material. Therefore, although the hat is lightweight and strong, it can feel stuffy when worn for long periods of time, and further improvement in breathability is desired. Also, as described above, the inner body 111 is shaped like a roughly spherical, curved bowl to fit a human head, and is made of a fiber-reinforced plastic (FRP) material obtained by impregnating a unidirectional or woven reinforced fiber sheet with resin and curing the resin. However, the unidirectional or woven reinforced fiber sheet before resin impregnation has problems with stretchability and drapeability, and further improvement in moldability (shapeability) is desired.

[0007] Patent Document 2 discloses a sheet-shaped carbon fiber knitted fabric knitted using carbon fibers, and describes that the sheet-shaped carbon fiber knitted fabric has excellent stretchability and drapeability.

[0008] The present inventors have focused on the excellent stretchability and drapeability of the sheet-like carbon fiber knitted fabric described in Patent Document 2, and have discovered that a mesh-like reinforced fiber composite material produced by impregnating a sheet-like carbon fiber woven fabric with a predetermined amount of resin and curing it while maintaining the predetermined opening ratio of the sheet-like carbon fiber knitted fabric provides excellent breathability and prevents stuffiness, and is also lightweight and strong when used as a material for constituting the basic structure of interior materials (innerwear) for hats, various types of protectors, and artificial limbs (artificial legs, artificial arms), or exterior materials (frames).

[0009] Therefore, the present inventors have proposed a mesh-like fiber-reinforced composite material 10A having voids G configured as described in Patent Document 3 and as shown in Figures 8(a) and (b) attached to the present application, which has: (a) a mesh-like knitted structure 1A having voids G formed by a plurality of vertical knitted structures 20 produced by knitting chain stitch yarns 2 in a loop shape while continuously forming chain stitches 2A in the vertical direction, and insertion yarns 3 that are inserted horizontally into the vertical knitted structures 20 and bind adjacent knitted structures 20 together; (b) a mesh-like fiber-reinforced composite material 10A formed into a shape having a curved surface, which is obtained by impregnating only the knitted structures 20 (chain stitch yarns 2) and the insertion yarns 3 in the mesh-like knitted structure 1A with a resin R and hardening the resin; (c) at least some of the chain stitch yarns 2 and the insertion yarns 3 are carbon fiber strands made of carbon fiber; and (d) the opening ratio of the mesh-like knitted structure 1A is 20 to 60%.

[0010] The mesh-like knitted structure 1A used in the mesh-like fiber-reinforced composite material 10A described in Patent Document 3 has excellent stretchability and drapeability, and excellent moldability (shapeability) into curved shapes, because the reinforcing fibers used are not straight but have a knitted structure.Furthermore, because it has voids G, it has excellent breathability and can prevent stuffiness, is lightweight and has sufficient strength, and has the characteristics of being able to form the basic structure of interior materials (innerwear) for hats, various types of protectors, prosthetic limbs (prosthetic legs, prosthetic hands), etc., or exterior materials (frames).

[0011] Utility Model Registration No. 3187008 Patent No. 4822528 Patent No. 6362454

[0012] The mesh-like knitted structure 1A used in the mesh-like fiber-reinforced composite material 10A described in Patent Document 3 has excellent stretchability and drapeability, and is excellent in formability into shapes having curved surfaces. However, even if carbon fiber strands made of carbon fiber are used for at least some of the chain stitch yarns 2 and the inserting yarns 3, the mesh-like fiber-reinforced composite material 10A that has been impregnated with resin and cured is prone to breakage from the resin due to external force, and it has been found that when used in a headgear such as a helmet, for example, if stress (impact) is applied by a falling object or the like, bending (distortion) is likely to occur in the stressed portion, and mechanical strength such as tensile strength and bending elasticity is also reduced.

[0013] To explain further, knitted structures are generally easily deformed, i.e., have high drapeability, making them suitable fabrics and substrates for producing deep-drawn products. However, this also means that the mechanical properties of the product, such as tensile strength, elasticity, and bending modulus, are low. The reasons for this are: (1) When stress is applied, the substrate itself is knitted, so it is easily deformed. Also, (2) the breaking strength of the loops that make up the knitted fabric is derived from the knot strength of the fibers, and this knot strength is lower than normal tensile strength. (For example, carbon fiber has zero knot strength, so it is not suitable as a fiber to use for loops.)

[0014] For this reason, when stress (impact) is applied to the surface of a molded product, the stressed area will bend and distort. If the amount of bending or distortion is large, the stress will be transmitted to the lower part of the molded product. In addition, as the knitted fabric or molded body deforms, the loops that make up the knitted fabric, made of fibers with low knot strength, will rupture, destroying the molded body.

[0015] Therefore, the present inventors attempted to solve the above problems by providing a knitted fabric and a base material that can withstand deep drawing during molding.

[0016] In other words, the object of the present invention is to provide a mesh-like fiber-reinforced composite material that is made of a knitted fabric base material that can withstand deep drawing during molding, has better stretchability and drape than general materials, is excellent in moldability into curved shapes and breathability, prevents stuffiness, is lightweight and strong, and also has high rigidity and excellent impact resistance, as well as a mesh-like knitted structure, a material for molding a mesh-like fiber-reinforced composite material, and a mesh-like fiber-reinforced composite molded body.

[0017] The above-mentioned problems and objects are solved and achieved by the mesh-like fiber-reinforced composite material, mesh-like knitted structure, mesh-like fiber-reinforced composite molding material, and mesh-like fiber-reinforced composite molding of the present invention by the following (1) to (4): (1) Increasing the knot strength of the fibers that make up the loops. (2) Using fibers with high fineness. (3) Specifying the type of fiber to be used. (4) Specifying a knitting structure with excellent impact resistance.

[0018] In summary, according to the first aspect of the present invention, there is provided a mesh-like knitted structure formed of three types of yarns: a knitted structure having a plurality of rows in which chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction; a plurality of rows of weft insertion yarns which are inserted by turning back and forth through the knitted structure in the vertical direction in three or more rows per course; and a warp insertion yarn which is inserted in a direction opposite to the direction of the weft insertion yarns in a plurality of rows by turning back and forth one row per course; and a mesh-like fiber reinforced composite material obtained by impregnating only the knitted structure in the mesh-like knitted structure and the warp and weft insertion yarns with a resin and hardening the resin, wherein the chain stitch yarns are: (a) organic fibers such as polyester, nylon, vinylon, etc.; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, high-strength polyarylate long fibers, etc.; or (c) inorganic fibers such as glass long fibers, basalt fibers, etc.; and the warp and weft insertion yarns are: (a) inorganic fibers such as glass long fibers, basalt fibers, etc.; (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers.

[0019] According to the second aspect of the present invention, there is provided a mesh-like knitted structure in a sheet form formed of three types of yarns: a knitted structure in which chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction; a knitted structure in which multiple rows of weft insertion yarns are inserted by turning back and forth through the knitted structure in the vertical direction in three or more rows per course; and a knitted structure in which multiple rows of warp insertion yarns are inserted by turning back and forth through the knitted structure in the horizontal direction in one row per course in the opposite direction to the warp insertion yarns; the mesh-like knitted structure is shaped into a predetermined shape, and then only the knitted structure in the mesh-like knitted structure and the warp and weft insertion yarns are impregnated with a resin and hardened, to provide a mesh-like fiber-reinforced composite material; the chain stitch yarns are: (a) organic fibers such as polyester, nylon, vinylon, etc.; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers; or (c) inorganic fibers such as glass long fibers and basalt fibers; and the knitted structure and weft insertion yarns are: The present invention provides a mesh-shaped fiber-reinforced composite material, characterized in that the fiber is: (a) an inorganic fiber such as a long glass fiber or a basalt fiber; or (b) a high-strength fiber such as an aramid long fiber, a PBO long fiber, an ultra-high molecular weight polyethylene fiber, or a high-strength polyarylate long fiber.

[0020] According to one embodiment of the first and second present inventions, the resin impregnated into the mesh-like knitted structure is a thermosetting resin such as a room temperature curing or thermosetting epoxy resin, vinyl ester resin, MMA resin, acrylic resin, unsaturated polyester resin, or phenolic resin; or a thermoplastic resin such as a thermoplastic epoxy resin, phenoxy resin, polycarbonate resin, polyester resin, polyurethane resin, polyamide resin, polyetherimide resin, polyether ether ketone resin, or polyphenylene sulfide resin.

[0021] According to a third aspect of the present invention, there is provided a sheet-like mesh-like knitted structure formed of three types of yarns: a knitted structure having a plurality of rows in which chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction; a plurality of rows of weft insertion yarns which are inserted by turning back and forth through the vertical knitted structure in the horizontal direction for three or more rows per course; and a plurality of rows of vertical insertion yarns which are inserted by turning back and forth the chain stitch yarns in one row per course in the opposite direction to the horizontal insertion yarns; and a mesh-like fiber-reinforced composite material which is obtained by impregnating only the knitted structure in the mesh-like knitted structure and the vertical and horizontal insertion yarns with a resin, hardening the resin, and then forming it into a predetermined shape; wherein the chain stitch yarns are: (a) organic fibers such as polyester, nylon, vinylon, etc.; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, high-strength polyarylate long fibers, etc.; or (c) inorganic fibers such as glass long fibers, basalt fibers, etc.; and the vertical and horizontal insertion yarns are: (a) inorganic fibers such as glass long fibers, basalt fibers, etc. (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers.

[0022] According to one embodiment of the third invention, the resin impregnated into the mesh-like knitted structure is a thermoplastic resin such as a thermoplastic epoxy resin, a phenoxy resin, a polycarbonate resin, a polyester resin, a polyurethane resin, a polyamide resin, a polyetherimide resin, a polyetheretherketone resin, or a polyphenylene sulfide resin.

[0023] According to one embodiment of the present invention, the fibers used for the chain stitch yarns are single yarns or plied yarns of 40 tex or more, and the fibers used for the warp and weft insert yarns are single yarns or plied yarns of 80 tex or more.

[0024] According to one embodiment of the present invention, the mesh-like knitted structure has an opening ratio of 20 to 60%.

[0025] Furthermore, according to the fourth aspect of the present invention, there is provided a mesh-like knitted structure formed from three types of yarn: a knitted structure having multiple rows in which chain stitches are formed by continuous loops of chain knitting yarn in the vertical direction; multiple rows of horizontal insertion yarn that are inserted by folding back and forth through the vertical knitted structure in the horizontal direction for at least three rows per course; and a vertical insertion yarn that is inserted in a direction opposite to the horizontal insertion yarn for multiple rows by swinging one row per course.

[0026] According to a fifth aspect of the present invention, there is provided a mesh-like knitted structure formed of three types of yarns: a knitted structure having a plurality of rows in which chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction; a plurality of rows of weft insertion yarns which are inserted by turning back and forth through the knitted structure in the vertical direction for three or more rows in every course; and a warp insertion yarn which is inserted in a direction opposite to the direction of the weft insertion yarns for a plurality of rows by turning back and forth once in every course; wherein only the knitted structure and the warp and weft insertion yarns in the mesh-like knitted structure are impregnated with a resin; the chain stitch yarns are: (a) organic fibers such as polyester, nylon, vinylon, etc.; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, high-strength polyarylate long fibers, etc.; or (c) inorganic fibers such as glass long fibers, basalt fibers, etc.; and the warp and weft insertion yarns are: (a) inorganic fibers such as glass long fibers, basalt fibers, etc.; (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers.

[0027] According to a sixth aspect of the present invention, there is provided a mesh-shaped fiber-reinforced composite molding obtained by shaping the above-mentioned mesh-shaped fiber-reinforced composite molding material.

[0028] The mesh-like fiber-reinforced composite material of the present invention is composed of a knitted fabric substrate that can withstand deep drawing during molding, and has excellent stretchability and drapeability and is easily moldable into curved shapes. Moreover, it has excellent breathability, preventing stuffiness, is lightweight and has sufficient strength, and has high rigidity and improved impact resistance. Therefore, it is suitable for filters, covers, and reinforcing members, but is particularly ideal as a component constituting the basic structure of various protectors, interior materials (innerwear) for prosthetic limbs (prosthetic legs, prosthetic hands), and exterior materials (frames). Furthermore, the mesh-like fiber-reinforced composite material of the present invention can be suitably produced using the mesh-like knitted structure and mesh-like fiber-reinforced composite molding material of the present invention. Furthermore, this mesh-like fiber-reinforced composite molding material can be shaped to suitably produce a mesh-like fiber-reinforced composite molded product of a desired shape.

[0029] FIG. 1 is a partial knitted structure diagram showing one embodiment of a mesh-like knitted structure according to the present invention. FIG. 2 is an enlarged schematic view of the mesh-like knitted structure shown in FIG. 1. FIG. 3 is a partial knitted structure diagram showing another embodiment of a mesh-like knitted structure according to the present invention. FIG. 4 is a schematic view of a conventional mesh-like knitted structure showing a comparative example of the present invention. FIGS. 5(a) to 5(e) are diagrams illustrating one embodiment of a method for molding a mesh-like fiber-reinforced composite material according to the present invention. FIGS. 6(a) and 6(b) are diagrams illustrating another embodiment of a method for molding a mesh-like fiber-reinforced composite material according to the present invention. FIGS. 7(a) and 7(b) are diagrams illustrating one embodiment of a hat in which the mesh-like fiber-reinforced composite material according to the present invention can be used as an inner material. FIG. 8(a) is a partial knitted structure diagram showing an example of a mesh-like knitted structure described in Japanese Patent No. 6,362,454, and FIG. 8(b) is a cross-sectional schematic view illustrating the resin impregnation state of the mesh-like knitted structure.

[0030] The mesh-like fiber-reinforced composite material, mesh-like knitted structure, mesh-like fiber-reinforced composite molding material, and mesh-like fiber-reinforced composite molding according to the present invention will be described in more detail below with reference to the drawings.

[0031] In this specification, "hardening" includes not only hardening of a thermosetting resin by forming a three-dimensional network structure, but also solidification of a thermoplastic resin from a fluid state.

[0032] Example 1 One example of a mesh-like fiber reinforced composite material according to the present invention will be described with reference to Fig. 1. Fig. 1 is a partially enlarged knitted structure diagram for illustrating a sheet-like reinforcing fiber knitted fabric configured according to the present invention, in particular a mesh-like knitted structure that is a sheet-like reinforcing fiber warp knitted fabric, i.e., a mesh-like fiber sheet 1.

[0033] The mesh-shaped fiber reinforced composite material according to the present invention has a knitted structure in the form of a mesh sheet, and is a mesh-shaped fiber reinforced composite material (FRP) obtained by impregnating the mesh-shaped knitted structure 1 with resin and curing it while maintaining the mesh (void portions) G formed in the mesh-shaped knitted structure 1. In other words, the mesh-shaped fiber reinforced composite material according to the present invention is a mesh-shaped fiber reinforced composite material (FRP) obtained by impregnating each constituent yarn of the mesh-shaped knitted structure 1 shown in Fig. 1 with resin and curing it.

[0034] As mentioned above, when stress (impact) is applied to the surface of a molded article formed from a mesh-like fiber-reinforced composite, deflection and distortion occur in the stressed area. If the amount of deflection and distortion is large, the stress is transmitted to the lower part of the molded article. Furthermore, when stress is applied to an FRP that uses a knitted fabric substrate such as circular knit, weft knit, or warp knit, failure generally occurs through rupture of the loops that make up the knitted fabric, which has low knot strength. To solve this problem, the following can be considered: (1) Increasing the knot strength of the fibers that make up the loops; (2) Using fibers with a high fineness; (3) Specifying the type of fiber used; and (4) Specifying a knitting structure with excellent impact resistance.

[0035] The present invention aims to solve the above problems and provide a knitted fabric substrate that can withstand deep drawing during molding.

[0036] Generally, damage to knitted fabrics caused by an impact from above begins with the chain stitch yarn breaking, causing the yarn to unravel. To prevent chain stitch yarn breakage, (1) increase the strength of the chain stitch yarn. That is, improve cut resistance by considering the material and thickness. (2) Have other yarns bear the load borne by the chain stitch yarn. That is, by swinging the main warp yarns in the opposite direction to the main weft yarns, the yarns cross and bear the load. (3) Having main yarns on both sides of the chain stitch yarn reduces eccentricity in the warp direction. (4) Reduce the difference in yarn amount between the main warp and weft yarns to suppress the difference in deformation due to the difference in direction. (5) To prevent chain stitch yarn breakage and the collapse of the knitting structure, swing the main warp yarns in at least three rows (needles). Even if one chain stitch yarn breaks, one of the main warp yarns will not unravel, and the main weft yarns can bear the load. However, the remaining structure due to the broken chain stitch yarns has a wider vertical spacing and a reduced yarn amount, significantly reducing its strength. (6) It is important that the chain stitch yarn and the main yarn have similar physical properties.

[0037] 1, the mesh-like knitted structure 1 according to the present invention is a mesh-like sheet formed of three types of yarns: a knitted structure 20 in which chain stitch yarns 2 are looped continuously in the vertical direction to form stitches 2A; a plurality of rows of weft insertion yarns 3 which are inserted by turning back and forth between the vertical knitted structure 20 in the horizontal direction in three or more rows, for example, three to six rows, per course; and a plurality of rows of warp insertion yarns 4 which are inserted vertically in the opposite direction to the weft insertion yarns 3, one row per course. The mesh-like knitted structure may also be a web or a ribbon.

[0038] The mesh-like knitted structure 1 is formed by impregnating only the chain stitch yarns 2, weft insert yarns 3, and warp insert yarns 4 of the mesh-like knitted structure 1 with resin after or before being formed into a predetermined shape. That is, as will be described in detail later, the mesh-like knitted structure 1 is formed into a predetermined shape, and then only the chain stitch yarns 2, weft insert yarns 3, and warp insert yarns 4 that form the mesh-like knitted structure 1 are impregnated with resin and hardened to form a mesh-like fiber-reinforced composite material of the predetermined shape; alternatively, the mesh-like knitted structure 1 is first impregnated with resin only the chain stitch yarns 2, weft insert yarns 3, and warp insert yarns 4 and hardened, and then heated and molded into a mesh-like fiber-reinforced composite material of the predetermined shape. The mesh-like knitted structure 1 configured as described above has excellent drapeability and can be deep-drawn, making the molding process for forming the composite material extremely simple.

[0039] A typical warp knitted fabric substrate is formed from loops of chain stitch yarn 2 and insert yarns that straddle two or more rows of the chain stitch yarn 2 and turn back. This means that the strongest tensile strength in the pulling direction, which is a characteristic of the fiber, cannot be utilized, making the yarn prone to breakage, destroying the knitted structure 20 and making it difficult to achieve rigidity. The main cause of destruction of the knitted structure 20 is that the loops of the chain stitch yarn 2 break, making it impossible to bind the horizontal and vertical insert yarns 3, 4. The mesh-like knitted structure 1 according to the present invention achieves rigidity by compensating for the characteristics of the above-mentioned typical warp knitted fabric using the materials used and the knitted structure.

[0040] A typical warp knitted fabric substrate is formed from loops of chain stitch yarn 2 and horizontal and vertical insertion yarns 3, 4 that twist the chain stitch yarn 2 in two or more rows, so it is highly stretchable in all directions and has good shaping properties. The mesh-like knitted structure 1 of the present invention has almost no stretch in the vertical direction, but shrinks in the vertical direction and expands and contracts in the horizontal direction. Although its shaping properties are inferior to those of a typical warp knitted fabric substrate, it can be shaped into a hemispherical shape without any problems.

[0041] Next, the mesh-like knitted structure 1 constituting the mesh-like fiber-reinforced composite material of the present invention will be further described.

[0042] (Mesh-like knitted structure) Referring to Figure 1, the mesh-like knitted structure 1 that constitutes the mesh-like fiber-reinforced composite material of the present invention has, as described above, chain stitch yarns 2 that form the knitted structure 20, weft insertion yarns 3 that are inserted horizontally into the vertical knitted structure 20, and vertical insertion yarns 4 that insert the chain stitch yarns 2 in the opposite direction to the weft insertion yarns 3.

[0043] In the mesh-like knitted structure 1 of the present invention, the chain stitch yarns 2 are: (a) organic fibers such as polyester, nylon, vinylon, etc., or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, high-strength polyarylate long fibers, etc., or (c) inorganic fibers such as glass long fibers, basalt fibers, etc.; and the weft insertion yarns 3 and the warp insertion yarns 4 are: (a) inorganic fibers such as glass long fibers, basalt fibers, etc., or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, high-strength polyarylate long fibers, etc.

[0044] As described above, the chain stitch yarn 2 used in the present invention is preferably selected according to the intended use of the mesh-like fiber-reinforced composite material, using organic fibers such as polyester, nylon, and vinylon, or high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers, or inorganic fibers such as glass long fibers and basalt fibers, as single yarns or plied / twisted yarns. If the count is too fine, the impact strength of the mesh-like fiber-reinforced composite material will decrease, so the count should be 40 tex or more, and should be selected according to the intended use of the mesh-like fiber-reinforced composite material.

[0045] The weft insertion yarns 3 used in the present invention are preferably selected as single yarns or doubled / twisted yarns from inorganic fibers such as glass fiber and basalt fiber, as well as high-strength fibers such as aramid fiber, PBO fiber, ultra-high molecular weight polyethylene fiber, and high-strength polyarylate fiber, depending on the intended use of the mesh-like fiber-reinforced composite material. Since strength cannot be achieved if the yarn count is too small, the yarn count should be at least 80 tex, preferably 100 tex, depending on the intended use of the mesh-like fiber-reinforced composite material.

[0046] The warp insert yarns 4 used in the present invention are preferably selected as single yarns or doubled / twisted yarns from inorganic fibers such as glass fiber and basalt fiber, as well as high-strength fibers such as aramid fiber, PBO fiber, ultra-high molecular weight polyethylene fiber, and high-strength polyarylate fiber, depending on the intended use of the mesh-like fiber-reinforced composite material. Since strength cannot be achieved if the yarn count is too small, the yarn count should be at least 80 tex, preferably 100 tex, depending on the intended use of the mesh-like fiber-reinforced composite material.

[0047] The mesh-shaped fiber-reinforced composite material of the present invention is a mesh-shaped fiber-reinforced composite material formed into a curved shape by impregnating and hardening only the knitted structure 20 (chain stitch yarn 2) and the warp and weft insertion yarns 4, 3 in the mesh-shaped knitted structure shown in Figure 1 with resin.

[0048] To further improve the impact resistance of the FRP in the mesh-shaped fiber-reinforced composite material of the present invention, it is preferable to use a resin with high breaking elongation so as to increase the impact energy absorption in the resin portion. Thermoplastic resins include thermoplastic epoxy resins, phenoxy resins, polycarbonate resins, polyester resins, polyurethane resins, polyamide resins, polyetherimide resins, polyether ether ketone resins, and polyphenylene sulfide resins. Thermosetting resins include room-temperature curing or thermosetting epoxy resins, vinyl ester resins, MMA resins, acrylic resins, unsaturated polyester resins, and phenolic resins. Resins with high breaking elongation, with a breaking elongation of 4% or more, are preferred.

[0049] The thermoplastic epoxy resin is a linear polymer exhibiting thermoplasticity, which is produced by chain extension of a bifunctional epoxy compound and a bifunctional phenolic compound through addition polymerization accompanied by ring-opening of the epoxy ring. For example, it can be obtained by blending bisphenol A epoxy resin and bisphenol A in a functional group ratio of 1:1, and polymerizing the mixture in situ in the presence of a phosphorus-based polymerization catalyst.

[0050] The mesh-like knitted structure 1 according to the present invention is almost inelastic in the vertical direction, but shrinks in the vertical direction and expands and contracts in the horizontal direction. Although its shapeability is inferior to that of a general warp-knitted fabric substrate, it can be easily shaped into a hemispherical shape.

[0051] A typical warp knitted fabric base material is formed by loops of chain stitch yarn 2 and weft insert yarn 3 that loops the chain stitch yarn 2 in two or more rows. The weft insert yarn 3 is folded back and bound to the chain stitch yarn 2, so the load received by the weft insert yarn 3 is always transmitted to the chain stitch yarn 2. Because the chain stitch yarn 2 has the property of forming loops and is often made of a fine count yarn in consideration of knitting workability, it has low strength and is the first to break.

[0052] In contrast, the mesh-like knitted structure 1 according to the present invention uses, for example, polyester long fibers for the chain stitch yarns 2, and by increasing the amount of fiber used compared to ordinary yarns and increasing the cross-sectional area, the cross-sectional performance is improved, thereby increasing the strength of the chain stitch yarns 2. Furthermore, by binding the warp insert yarns 4 along the chain stitch yarns 2 one row at a time in the opposite direction to the weft insert yarns 3, the weft insert yarns 3 and the warp insert yarns 4 cross at the loop portions, thereby causing the load received by the chain stitch yarns 2 to be borne by the warp insert yarns 4 and reducing the load received. By swinging the weft insert yarns 3 back and forth across three rows of the chain stitch yarns 2, the number of rows of the chain stitch yarns 2 that receive the load becomes four, thereby reducing the load borne by one row of the chain stitch yarns 2. The weft insert yarns 3 are not limited to being inserted across three rows of the chain stitch yarns 2, and can also be inserted into the chain stitch yarns 2 by swinging them back and forth across four or more rows, for example. As can be seen from the shape of Figure 1, even if one row of chain stitch yarn 2 is destroyed and the knitting structure 20 is destroyed, the weft insertion yarn 3 binds the chain stitch yarn 2 across three or more rows, so this does not lead to large-scale destruction of the knitting structure 20.

[0053] As can be seen from the above, in Figure 2, the load that acts most heavily on the chain stitch yarn 2 is the hook load at the intersection of force P3, which is generated when the weft insertion yarn 3 tries to stretch laterally due to deformation when the mesh-like knitted structure 1 receives an impact, and force P4, which is generated when the warp insertion yarn 4 tries to stretch vertically. Therefore, by improving the cross-sectional performance of the chain stitch yarn 2 and dispersing the load it receives, the chain stitch yarn 2 is less likely to break, and the mesh-like knitted structure 1 becomes a structure that is resistant to impact loads.

[0054] Specific Example 1 In one specific example of the present invention, the mesh-like knitted structure 1 is a mesh-like sheet knit fabric formed by using polyester fiber as the chain stitch yarns 2 and long glass fiber as the weft insertion yarns 3 and warp insertion yarns 4.

[0055] The mesh-like knitted structure 1 of this specific example 1 will be described with reference to Figure 1. In this specific example 1, the knitting structure 20 in the mesh-like knitted structure 1 has chain stitch yarns 2 that form loops in the vertical direction, and weft insertion yarns 3 and warp insertion yarns 4 that are knitted into the loops and bound together. The shape of the loops in the knitting structure 20 shown in this specific example (so-called Russell stitch) can also be a tricot stitch, or a combination of the Russell stitch and tricot stitches of this specific example. The knitting structure 20 in the mesh-like knitted structure 1 is desirably selected depending on the intended use of the mesh-like fiber-reinforced composite material.

[0056] In this specific example 1, polyester fiber 110 tex was used as the polyester fiber used as the chain stitch yarn 2 forming the knitted texture 20 in the mesh-like knitted structure 1.

[0057] The long glass fibers used as the weft insertion yarns 3 and the warp insertion yarns 4 are classified into various types such as E glass, T glass, and NE glass depending on the characteristics of the glass, but E glass (general-purpose product) was used in this specific example 1. It is desirable to select the long glass fibers depending on the intended use of the mesh-like fiber-reinforced composite material.

[0058] The long glass fibers are available in various types and counts, such as glass yarn, glass direct roving, and glass doped roving, depending on the manufacturing method. It is desirable to select the count according to the purpose of use of the mesh-like fiber-reinforced composite material and the mesh size. Furthermore, if the count of the long glass fibers used is too small, they will not have enough strength, so as mentioned above, a count of 100 tex or more is desirable. In this specific example 1, the long glass fibers used in the weft insertion yarns 3 and the warp insertion yarns 4 were glass yarn doped and twisted yarns of 420 tex.

[0059] That is, in this specific example 1, the mesh-like knitted structure 1 is a mesh-like sheet formed of three types of yarns: a knitted structure 20 in which multiple rows of chain stitch yarns 2 using polyester fiber 110 tex are looped continuously in the vertical direction to form stitches; a horizontal insertion yarn 3 using long glass fiber 420 tex in multiple rows, which is inserted by folding back and inserting the horizontal chain stitch yarns 2 across three or more rows in every course; and a vertical insertion yarn 4 using long glass fiber 420 tex in multiple rows, which is inserted in the vertical direction in the opposite direction to the horizontal insertion yarn 3, with one row in every course. The mass of the mesh-like knitted structure 1 in this specific example 1 is 476 g / m ２ is.

[0060] The mesh knitted structure 1 of this Example 1 can be produced using a single Russell knitting machine, and can also be knitted using a tricot knitting machine, a crochet knitting machine, etc. Such knitting manufacturing methods are well known in the art, so further detailed explanations will be omitted.

[0061] According to another specific example 2 of the present invention, the mesh-like knitted structure 1 is a mesh-like sheet knit fabric formed by using aramid long fibers as the chain stitch yarns 2 and glass long fibers as the weft insertion yarns 3 and warp insertion yarns 4.

[0062] In this Example 2, the aramid continuous fiber used for the chain stitch yarn 2 is an 88 tex yarn obtained by plying and twisting standard para-aramid fiber.

[0063] The mesh-like knitted structure 1 of this specific example 2 also has a knitting structure similar to that of the mesh-like knitted structure 1 of specific example 1 described with reference to Figure 1, and the difference between this specific example 2 and specific example 1 is that the chain stitch yarn 2 is changed to aramid long fiber, particularly aramid long fiber ply-twisted yarn 88 tex. This change increases the strength of the chain stitch yarn, improving the impact load resistance of the mesh-like knitted structure 1 of this specific example 2. The mass of the mesh-like knitted structure 1 of this specific example 2 is 461 g / m ２ is.

[0064] The mesh knitted structure 1 of Example 2 can be produced using a single Russell knitting machine, and can also be knitted using a tricot knitting machine, a crochet knitting machine, etc. Such knitting manufacturing methods are well known in the art, and therefore further detailed explanations will be omitted.

[0065] Next, another specific example 3 of the present invention will be described with reference to Fig. 3. The knitting pattern 20 of the mesh-like knitted structure 1 used in this specific example 3 is not limited to the above specific example. As shown in Fig. 3, the loop shape of the chain stitch yarn 2 can be a tricot pattern.

[0066] In this specific example 3, the chain stitch yarn 2 and the weft and warp insertion yarns 3 and 4 that form the tricot weave used in the mesh-like knitted structure 1 are the same as those described in the above examples and specifically described in the above specific examples 1 and 2, and are selected appropriately depending on the intended use of the mesh-like fiber-reinforced composite material.

[0067] (Opening ratio) In the present invention, the opening ratio of the mesh-like fiber-reinforced composite material 10 produced using the mesh-like knitted structure 1 is important, and as will be described in detail later, the opening ratio is 20 to 60%, preferably 20 to 50%, and more preferably 30 to 50%.

[0068] According to the present invention, the mesh-like knitted structure 1 is impregnated with resin and hardened only in the knitting structure 20 formed by the chain stitch yarn 2 and the warp and weft insertion yarns 4, 3 in the mesh-like knitted structure 1. In other words, the resin is not filled in the voids G in the mesh-like knitted structure 1, so the opening rate of the mesh-like fiber-reinforced composite material 10 is substantially the same as the opening rate of the mesh-like knitted structure 1.

[0069] The open area ratio generally means the rate at which holes are formed on a plane, for example, in mesh fabrics used in screen printing or punched metal. Similarly, in the present invention, the open area ratio of the mesh knitted structure 1 means the rate at which holes are formed on a plane of the mesh knitted structure 1. The mesh knitted structure 1 is scanned with a two-dimensional scanner, and the ratio of the area with fibers to the area without fibers is calculated. In practice, the open area ratio is calculated by scanning with a two-dimensional scanner and dividing it into void areas and fibrous areas using image software. For example, such an open area ratio can be efficiently determined using a two-dimensional scanner (trade name "CanoScan4400F") manufactured by Canon Inc. Open area ratio (%) = {(area of ​​void areas) / (area of ​​fiber areas + area of ​​void areas)} x 100

[0070] As described above, in the present invention, the opening ratio of the mesh-like knitted structure 1 is set to 20 to 60%. If the opening ratio is less than 20%, the rigidity is very good, but the holes do not open after molding, the breathability is poor, and the structure becomes very heavy. If the opening ratio exceeds 60%, the breathability is very good and the structure is lightweight, but the amount of reinforcing fibers as a whole is insufficient, resulting in insufficient rigidity. Preferably, the opening ratio is set to 20 to 50%, more preferably 30 to 50%.

[0071] In the present invention, the size of each opening (hole) in the mesh-like knitted structure 1 is also important, and the area of ​​each opening is 1.5 to 80 mm ２ It is important that the opening area per piece is 1.5 mm ２ If it is less than this, there is a possibility that holes will not be formed during molding, and the opening area will be 80 mm ２ If the mesh size exceeds this value, the mesh after molding may become too large, and the mesh-like fiber-reinforced composite material 10 may lose its rigidity.

[0072] (Impregnating Resin) In the present invention, as described above, after or before shaping the mesh-like knitted structure 1 into a predetermined shape, only the knitted texture 20 and the warp and weft insertion yarns 4, 3 in the mesh-like knitted structure 1 are impregnated with a resin and hardened to form the mesh-like fiber-reinforced composite material 10. The fiber content in the mesh-like fiber-reinforced composite material 10 is 30 to 70%, preferably 40 to 70%, by weight of the fiber.

[0073] In the above examples, examples of thermoplastic resins include thermoplastic epoxy resins, phenoxy resins, polycarbonate resins, polyester resins, polyurethane resins, polyamide resins, polyetherimide resins, polyether ether ketone resins, and polyphenylene sulfide resins, and examples of thermosetting resins include room temperature curing or thermosetting epoxy resins, vinyl ester resins, MMA resins, acrylic resins, unsaturated polyester resins, and phenolic resins. However, it is preferable to use a thermoplastic resin, more preferably a thermoplastic resin having a breaking elongation of 4% or more, even more preferably a thermoplastic resin having a breaking elongation of 10% or more, and most preferably a thermoplastic resin having a breaking elongation of 50% or more.

[0074] (Molding Method) Next, a method for molding the mesh-shaped fiber-reinforced composite material 10 according to the present invention will be described.

[0075] The mesh-shaped fiber reinforced composite material 10 can be formed using the same molding methods as those used for conventionally known fiber reinforced composite materials, such as press molding, sheet winding molding, tape winding molding, and hand bending molding.

[0076] 5(a) to (c) show a press molding method, which is one example of a molding method. In this press molding method, the mesh-like knitted structure 1 is fitted to a convex male mold 201, and by pressing, the mesh-like knitted structure 1 is molded to follow the shape of the male mold 201 (FIG. 5(a)). At this time, the mesh-like knitted structure 1 produced according to the present invention has good drapeability, stretchability, good moldability, and is easy to work with, as described above.

[0077] Next, resin R is applied to the mesh-like knitted structure 1 using an impregnation brush or the like so that the resin is impregnated only into the knitted structure 20 consisting of the chain stitch yarns 2 and the warp and weft insertion yarns 4, 3 of the mesh-like knitted structure 1 (FIG. 5(b)). The resin R may be a thermosetting resin or a thermoplastic resin. A concave female mold 202 is then placed on the male mold 201, and the resin R is hardened by applying a predetermined pressure and heating, thereby forming a mesh-like fiber-reinforced composite material 10 shaped into a predetermined shape (FIG. 5(c)). The mesh-like fiber-reinforced composite material 10 is then removed from the mold (FIG. 5(d)) and finished into the predetermined shape (FIG. 5(e)).

[0078] 6(a) and (b) show vacuum molding, another example of a molding method. According to this vacuum molding method, the mesh-like knitted structure 1 is formed by impregnating and curing only the knitted structure 20 consisting of chain stitch yarns 2 and the warp and weft insertion yarns 4, 3 with resin, forming a flat mesh-like knitted structure 1a made of FRP material. Although thermosetting resins can be used in a B-stage state, thermoplastic resins are preferred. Resin impregnation into the mesh-like knitted structure may be applied or impregnated in advance, or may be performed immediately before molding.

[0079] The mesh-like knitted structure 1, which has been impregnated with resin R by coating or immersion and cured, is placed on a concave vacuum mold (female mold) 202 as a mesh-like fiber-reinforced composite molding material 1a and further covered with a resin film 60 ( FIG. 6( a) ). The female mold 202 is evacuated, and a male mold 201 is pressed against the female mold 202 from the resin film 60 side with a predetermined pressure and heated. This softens (melts) the resin impregnated and cured in the mesh-like knitted structure 1a, thereby molding it to the shape of the female mold 202. The molding mold is cooled, yielding a mesh-like fiber-reinforced composite 10 shaped to the desired shape ( FIG. 6( b) ). Thereafter, as in the press molding method, the mesh-like fiber-reinforced composite 10 is removed from the mold and finished to the desired shape, as shown in FIGS. 5( d) and 5( e) .

[0080] Even in this vacuum molding method, when the resin is softened or melted, the mesh-like knitted structure 1 has good drapeability, stretchability, and formability, and can be molded to follow the male mold, making the process easy.

[0081] According to the vacuum molding method, the mesh-like knitted structure 1, which has been coated or impregnated with resin and cured in advance, can be used like a prepreg as the mesh-like fiber-reinforced composite molding material 1a, which has good productivity, and has the advantages that the pores of the mesh-like knitted structure 1 will not be crushed during molding, and the sheet thickness will not become thin during molding, resulting in a composite with a thick cross-section, making it easier to obtain high strength.

[0082] (Experimental Examples 1-2, Comparative Examples 1-2) Next, in order to verify the effects of the mesh-like fiber reinforced composite material 10 and mesh-like knitted structure 1 according to the present invention, the impact strength of the mesh-like fiber reinforced composite material was verified by changing the types of chain stitch yarns 2, weft insertion yarns 3, and warp insertion yarns 4 of the mesh-like knitted structure 1. Details of the mesh-like knitted structure 1 and the verification results of the impact strength of the mesh-like reinforced composite material are shown in Table 1.

[0083] In this experiment, the mesh-like knitted structure 1 was impregnated with a thermoplastic epoxy resin (trade name "XNR6850V" manufactured by Nagase ChemteX Corporation) as an impregnating resin, and the solvent was dried in an oven at 120°C for 10 minutes, followed by heating in a mold at 160°C for 30 minutes to produce a mesh-like fiber-reinforced composite material. At this time, the fiber content in the composite material was 65% by weight of the fiber.

[0084] Impact strength was verified by conducting a punching impact strength test (drop mass: 1.59 kg, drop height: 580 mm, striker: 20 mm hemispherical) using a mesh fiber composite material molded into a flat plate on an Instron universal testing machine "CEAST9310." In Table 1, "Peak Force / mass" is the maximum load per unit mass, and the larger this value, the more excellent the impact resistance of the structure can be determined.

[0085] Experimental Example 1 The mesh-like knitted structure 1 used in Experimental Example 1 used the mesh-like knitted structure 1 produced in Example 1 as the knitted fabric base material. Referring to Fig. 1, the shape is such that the spacing between warp rows (SB) is 4 mm and the spacing between cross rows (SA) is 5 mm. The chain stitch yarns 2 are 110 tex polyester fiber, the weft insert yarns 3 are 420 tex long glass fiber ply-twisted yarns, and the warp insert yarns 4 are 420 tex long glass fiber ply-twisted yarns. The mass of the mesh-like knitted structure 1 is 476 g / m ２ The aperture ratio was 45%.

[0086] The mesh-like fiber composite material 10 made using the mesh-like knitted structure 1 exhibited a maximum impact load of 852 N as a result of a punching impact strength test, and the knitted structure 20 was destroyed after the test.

[0087] Experimental Example 2 The mesh-like knitted structure 1 used in Experimental Example 2 used the mesh-like knitted structure 1 produced in Example 2 as the knitted fabric base material. The shape was such that the vertical row spacing (SB) was 4 mm and the horizontal row spacing (SA) was 5 mm. The chain stitch yarns 2 were aramid long fiber plied and twisted yarns of 88 tex, the weft insert yarns 3 were glass long fiber plied and twisted yarns of 420 tex, and the vertical insert yarns 4 were glass long fiber plied and twisted yarns of 420 tex. The mass of the mesh-like knitted structure 1 was 461 g / m ２ The aperture ratio was 40%.

[0088] The mesh-like fiber composite material 10 produced using the mesh-like knitted structure 1 of this experimental example showed a maximum impact load resistance of 1748 N in a punching impact strength test, and although the knitted structure 20 was deformed after the test, it did not break, confirming that the strength of the chain stitch yarn 2 has a significant effect on the impact load resistance.

[0089] Comparative Example 1 The knitted fabric substrate used in the mesh knitted structure 1 used in Comparative Example 1 had the same knitting pattern 20 as in Experimental Examples 1 and 2, with a vertical row spacing (SB) of 4 mm and a horizontal row spacing (SA) of 5 mm. The chain stitch yarn 2 was an aramid long fiber plied yarn of 88 tex, the horizontal insert yarn 3 was a carbon fiber strand of 400 tex, and the vertical insert yarn 4 was a carbon fiber strand of 400 tex. The mass of the mesh knitted structure 1 was 488 g / m ２ The aperture ratio was 29%.

[0090] The mesh-like fiber composite material 10 produced using the mesh-like knitted structure 1 of Comparative Example 1 showed a maximum impact load resistance of 1254 N in a punching impact strength test, and the knitted structure 20 was destroyed after the test.

[0091] In this comparative example, the long glass fibers of the horizontal and vertical inserted yarns 3 and 4 in Experimental Example 2 were replaced with carbon fiber strands, and the purpose was to compare the impact load resistance performance of the long glass fiber and the carbon fiber strands. The carbon fiber used in this comparative example had a count 20 less than the long glass fiber, but the specific gravity of the carbon fiber was 1.8 compared to 2.6 for the glass fiber, so that although the inserted yarn volume was 1.37 times larger, the maximum load resistance was only 72%, and it was confirmed that the carbon fiber strands were weaker against impact loads than the long glass fiber.

[0092] Furthermore, the volume of the carbon fiber is larger than the volume of the glass fiber, which reduces the opening ratio and results in poor ventilation.

[0093] Comparative Example 2 is a mesh-like fiber-reinforced composite material using the mesh-like knitted structure 1A shown in Fig. 4, and has a configuration similar to the mesh-like knitted structure 1A described in Patent Document 3 (Japanese Patent No. 6362454) and explained with reference to Figs. 8(a) and (b) attached to the present application. Comparative Example 2 was a mesh-like fiber-reinforced composite material 10A in which the chain stitch yarns 2 and weft insertion yarns 3 of this mesh-like knitted structure 1A were impregnated with resin and then cured.

[0094] The mesh knitted structure 1A used in Comparative Example 2 uses the knitting pattern shown in Figure 4, with a vertical row spacing (SB) of 4 mm and a horizontal row spacing (SA) of 5 mm. The chain stitch yarn 2 is an aramid long fiber plied and twisted yarn of 88 tex, and the weft insert yarn 3 is a glass long fiber plied and twisted yarn of 1145 tex. The mass of the mesh knitted structure 1A is 674 g / m ２ The aperture ratio was 38%.

[0095] The mesh-like fiber reinforced composite material 10A produced using the mesh-like knitted structure 1A of this comparative example 2 had a maximum impact load resistance of 441 N in a punching impact strength test, and the knitted structure 20 was destroyed after the test.

[0096] In Comparative Example 2, the load-bearing performance of a highly elastic knitted structure 20 was confirmed by reinforcing it with chain stitch yarn 2 and weft inserted yarn 3.Compared to Experimental Example 1, the strength of the chain stitch yarn 2 was greater and the fiber content of the weft inserted yarn 3 was greater, but the impact load resistance was only 53% of that of Experimental Example 1, confirming that the knitted structure 20 of the mesh-shaped fiber-reinforced composite shown in Experimental Example 2 is effective in resisting impact loads.

[0097] The mesh-like fiber composite material of the present invention is particularly suitable as an interior or exterior component for protectors such as protective helmets and prosthetic limbs (prosthetic legs and prosthetic hands), but is not limited thereto. It can also be used for medical supplies such as casts for immobilizing affected areas, clothing and equipment such as shoes and hats for sports and leisure, filters and housing components, reinforcing or protective components for pipes and hoses, reinforcing components for structures, and structural and decorative components for aircraft, rockets, satellites, automobiles, motorcycles, trains, bicycles, houses, optical equipment, home appliances, portable electronic devices, and other vehicles that require molding and processing into complex curved shapes while maintaining high rigidity. It can also be used for a wide range of industrial and consumer applications, including houses.

[0098]

[0099] REFERENCE SIGNS LIST 1 Mesh-shaped knitted structure 1a Mesh-shaped fiber-reinforced composite molding material 2 Chain stitch yarn 2A Chain stitch 3 Weft-insertion yarn 4 Warp-insertion yarn 10 Mesh-shaped fiber-reinforced composite material 20 Knitted structure

Claims

1. A mesh-like knitted structure formed of three types of yarns: a knitted structure in which multiple rows of chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction; multiple rows of horizontal insertion yarns that are inserted by turning back and forth through the knitted structure in the vertical direction for at least three rows per course; and vertical insertion yarns that are inserted in a direction opposite to the horizontal insertion yarns for multiple rows, with one row per course; a mesh-like fiber-reinforced composite material in which the knitted structure in the mesh-like knitted structure and only the vertical and horizontal insertion yarns are impregnated with resin and hardened; the chain stitch yarns are: (a) organic fibers such as polyester, nylon, and vinylon; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers; or (c) inorganic fibers such as glass long fibers and basalt fibers; and the vertical and horizontal insertion yarns are: (a) inorganic fibers such as glass long fibers and basalt fibers; or (b) A mesh-like fiber-reinforced composite material comprising high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers.

2. A mesh-like knitted structure in the form of a sheet formed of three types of yarns: a knitted structure in which multiple rows of chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction, multiple rows of horizontal insertion yarns that are inserted by turning back and forth through the vertical knitted structure in the horizontal direction for at least three rows per course, and multiple rows of vertical insertion yarns that are inserted vertically in the opposite direction to the horizontal insertion yarns, with the chain stitch yarns being turned one row per course; the mesh-like knitted structure is shaped into a predetermined shape, and then only the knitted structure in the mesh-like knitted structure and the vertical and horizontal insertion yarns are impregnated with a resin and hardened; the chain stitch yarns are: (a) organic fibers such as polyester, nylon, and vinylon; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers; or (c) inorganic fibers such as glass long fibers and basalt fibers; and the vertical and horizontal insertion yarns are:

1. A mesh-shaped fiber-reinforced composite material comprising: (a) inorganic fibers, such as long glass fibers and basalt fibers; or (b) high-strength fibers, such as long aramid fibers, long PBO fibers, ultra-high molecular weight polyethylene fibers, and long high-strength polyarylate fibers.

3. The mesh-shaped fiber-reinforced composite material according to claim 1 or 2, characterized in that the resin impregnated into the mesh-shaped knitted structure is a thermosetting resin such as room temperature curing or heat curing epoxy resin, vinyl ester resin, MMA resin, acrylic resin, unsaturated polyester resin, or phenolic resin; or a thermoplastic resin such as thermoplastic epoxy resin, phenoxy resin, polycarbonate resin, polyester resin, polyurethane resin, polyamide resin, polyetherimide resin, polyether ether ketone resin, or polyphenylene sulfide resin.

4. A mesh-like knitted structure having a sheet-like structure formed of three types of yarns: a knitted structure in which multiple rows of chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction, multiple rows of horizontal insertion yarns that are inserted by turning back and forth through the vertical knitted structure in three or more rows per course, and multiple rows of vertical insertion yarns that are inserted vertically in one row per course in the opposite direction to the horizontal insertion yarns; wherein the knitted structure in the mesh-like knitted structure and only the vertical and horizontal insertion yarns are impregnated with a resin and hardened, and then shaped into a predetermined shape; the chain stitch yarns are: (a) organic fibers such as polyester, nylon, and vinylon; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers; or (c) inorganic fibers such as glass long fibers and basalt fibers; and the vertical and horizontal insertion yarns are: (a) inorganic fibers such as glass long fibers and basalt fibers; (b) A mesh-like fiber-reinforced composite material comprising high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers.

5. The mesh-shaped fiber-reinforced composite material according to claim 4, characterized in that the resin impregnated into the mesh-shaped knitted structure is a thermoplastic resin such as a thermoplastic epoxy resin, a phenoxy resin, a polycarbonate resin, a polyester resin, a polyurethane resin, a polyamide resin, a polyetherimide resin, a polyether ether ketone resin, or a polyphenylene sulfide resin.

6. A mesh-like fiber-reinforced composite material as described in any one of claims 1 to 5, characterized in that the fibers used for the chain stitch yarns are single yarns or ply-twisted yarns with a fineness of 40 tex or more, and the fibers used for the warp and weft insertion yarns are single yarns or ply-twisted yarns with a fineness of 80 tex or more.

7. A mesh-like fiber-reinforced composite material according to any one of claims 1 to 6, characterized in that the opening ratio of the mesh-like knitted structure is 20 to 60%.

8. A mesh-like knitted structure formed from three types of yarn: a knitted structure in which multiple rows of chain stitches are formed by continuous loops of chain stitch yarn in the vertical direction, multiple rows of horizontal insertion yarns that are inserted by folding back and forth through the vertical knitted structure in the horizontal direction for at least three rows per course, and a vertical insertion yarn that is inserted in the opposite direction to the horizontal insertion yarn for multiple rows, with one row per course.

9. A mesh-like knitted structure formed of three types of yarns: a knitted structure in which multiple rows of chain stitches are formed by continuous loops of chain stitch yarns in the vertical direction; multiple rows of horizontal insertion yarns that are inserted by turning back and forth through the knitted structure in the vertical direction for three or more rows per course; and vertical insertion yarns that are inserted in a direction opposite to the horizontal insertion yarns for multiple rows, with the chain stitch yarns being turned one row per course; wherein only the knitted structure and the vertical and horizontal insertion yarns in the mesh-like knitted structure are impregnated with resin; the chain stitch yarns are: (a) organic fibers such as polyester, nylon, vinylon, etc.; or (b) high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers; or (c) inorganic fibers such as glass long fibers and basalt fibers; and the vertical and horizontal insertion yarns are: (a) inorganic fibers such as glass long fibers and basalt fibers, (b) A material for molding a mesh-shaped fiber-reinforced composite material, which is made of high-strength fibers such as aramid long fibers, PBO long fibers, ultra-high molecular weight polyethylene fibers, and high-strength polyarylate long fibers.

10. A mesh-like fiber-reinforced composite molding produced by molding the mesh-like fiber-reinforced composite molding material of claim 9.

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