JP7723001B2 - Mesh-like fiber reinforced composite material, mesh-like fiber reinforced composite molding material, and mesh-like fiber reinforced composite molded product - Google Patents

Description

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 mesh-like and therefore has a high opening ratio, is lightweight, high strength, and high impact resistance, and is therefore suitable for use as filters, covers, reinforcing members, and particularly as protectors such as safety helmets, and as interior and exterior members for prosthetic limbs (artificial legs, artificial arms).The present invention also relates to 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.

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

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.

20(a) and (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.

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.

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.

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.

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).

Therefore, the present inventors have developed a method for manufacturing a semiconductor device, as described in Patent Document 3 and as illustrated in FIGS. 21(a) and 21(b) attached to the present application,
(a) A mesh-like knitted structure 1A having gaps G formed by a plurality of vertical knitted structures 20 produced by knitting a chain stitch yarn 2 in a loop shape while continuously forming chain stitches 2A in the vertical direction, and an insertion yarn 3 inserted laterally into the vertical knitted structures 20 and binding adjacent knitted structures 20 together;
(b) A mesh-shaped fiber reinforced composite material 10A formed into a curved shape in which only the knitted structure 20 (chain stitch yarn 2) and the insertion yarn 3 in the mesh-shaped knitted structure 1A are impregnated with resin R and hardened,
(c) At least a part of the chain stitch yarn 2 and the inserting yarn 3 is a carbon fiber strand made of carbon fiber,
(d) We have proposed a mesh-like fiber-reinforced composite material 10A having voids G in the structure, in which the opening ratio of the mesh-like knitted structure 1A is 20 to 60%.

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).

Meanwhile, the present inventors have conducted further research and experiments on the mesh-like fiber-reinforced composite material 10A described in Patent Document 3, and as a result have found that, although 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 curved shapes, as described above, due to its stretchability, when the mesh-like fiber-reinforced composite material 10A is impregnated with resin and cured, i.e., when it is made into an FRP structure, there is a problem in that the resin breaks under a slight external force. Therefore, when the mesh-like fiber-reinforced composite material 10A using such a mesh-like knitted structure 1A is used in a hat or the like, if stress (impact) is applied to the surface of the hat by a dropped object or the like, bending (distortion) may occur in the stressed portion, making the hat prone to deformation and prone to reducing mechanical strength such as tensile strength and bending elasticity. Therefore, even if carbon fiber strands made of carbon fiber are used for at least some of the chain stitch yarns 2 and the insert yarns 3, as described above, due to their excellent elasticity and drapeability, the amount of deformation (amount of deflection) due to impact is large, and it has been found that further improvements are desired to obtain even greater strength and impact resistance.

Therefore, although the present inventors are in a different technical field in terms of application, they focused on the structure of the continuous fiber reinforcement member, i.e., the reinforcing fiber sheet, used to produce the fixing anchor described in Patent Document 4. That is, as shown in Figures 22(a), (b), and 23 attached to this application, the reinforcing fiber sheet 1B for the fixing anchor described in Patent Document 4 has a chain stitch portion (knitted structure) 20 produced by knitting a restraining yarn (i.e., chain stitch yarn) 2 in a loop shape continuously in the vertical direction while forming chain stitches 2A, and continuous fiber strands 50 are arranged orthogonally within the chain stitches 2A of this knitted structure 20.

In addition, in the knitted structure 20 that restrains each continuous fiber strand 50, adjacent knitted structures 20 are bound to each other by an insertion yarn 3. That is, the insertion yarn 3 is inserted laterally into the knitted structure 20 and is entangled at predetermined intervals along the longitudinal direction (i.e., the vertical direction) of the continuous fiber strands 50 with the knitted structure 20 knitted to surround the continuous fiber strands 50, thereby maintaining the shape of the multiple continuous fiber strands 50 in a planar state, i.e., a reinforcing fiber sheet state. That is, according to the reinforcing fiber sheet 1B described in Patent Document 4, the knitted structure 20 is formed by knitting the restraining yarns 2 continuously in the vertical direction and in a planar state, and continuous fiber strands 50 formed by bundling a large number of continuous reinforcing fibers in one direction are inserted into this knitted structure 20 continuously knitted in the vertical direction. The shape of each continuous fiber strand 50 inserted into the vertical knitted structure 20 is maintained by being connected by an insertion yarn 3 inserted laterally into the vertical knitted structure 20.

Utility Model Registration No. 3187008 Patent No. 4822528 Patent No. 6362454 Patent No. 4463657

Therefore, based on the technology described in Patent Document 4, the inventors inserted reinforcing fiber yarns 50 with vertical needles 1 into a plurality of vertical knitted structures 20 produced by knitting chain stitch yarns 2 in a continuous loop shape in the vertical direction to form chain stitches 2A in the mesh-like knitted structure 1A described in Patent Document 3, and inserted horizontal insertion yarns 3 horizontally into the vertical knitted structure 20 to produce a sheet-like mesh-like knitted structure, which was then impregnated with resin to produce a mesh-like fiber-reinforced composite material having a structure similar to that described in Patent Document 3, and continued to conduct research and experiments on this composite material.

While such a mesh-shaped fiber-reinforced composite material was able to achieve increased tensile strength and reduced tensile strain, it was found that when stress (impact) is applied to the surface of a hat using the mesh-shaped fiber-reinforced composite material, for example, by a dropped object, the chain stitch yarn 2 (knit structure 20) in the vertical direction that holds the reinforcing fiber yarns in the vertical direction in the stressed area lacks rigidity, causing the chain stitch yarn 2 to break, resulting in the mesh-shaped fiber-reinforced composite material not fully fulfilling the function of the reinforcing fiber yarn 50 that ensures the strength and impact resistance of the mesh-shaped fiber-reinforced composite material. Therefore, it was found that further improvements are desired to increase rigidity and obtain sufficient strength and impact resistance even when, for example, an object falls on the top of the hat.

Therefore, an object of the present invention is to provide a mesh-like fiber-reinforced composite material that is superior to conventional materials in terms of stretchability and drapeability, excellent in formability into curved shapes and breathability, preventing stuffiness, lightweight and high in strength, and also has high rigidity and excellent impact resistance, as well as a material for molding the mesh-like fiber-reinforced composite material and a mesh-like fiber-reinforced composite molded product.

The above object is achieved by the mesh-shaped fiber reinforced composite material , the material for molding the mesh-shaped fiber reinforced composite material, and the mesh-shaped fiber reinforced composite molding according to the present invention. In summary, according to the first aspect of the present invention, there is provided a mesh-shaped knitted structure formed by a plurality of vertical knitting structures produced by knitting a chain stitch yarn continuously in the vertical direction while forming chain stitches, a vertical insertion yarn inserted into one needle in the vertical direction along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitting structures to bind adjacent knitting structures together,
A mesh-shaped fiber reinforced composite material in which only the knitting structure and the warp and weft insertion yarns in the mesh-shaped knitted structure are impregnated with a resin and hardened,
At least the warp insert yarns of the chain stitch yarns and the warp and weft insert yarns are carbon fiber strands made of carbon fiber,
The opening ratio of the mesh-like knitted structure is 20 to 60%.
A mesh-like fiber-reinforced composite material is provided.

According to the second aspect of the present invention, there is provided a mesh-like knitted structure formed by a plurality of vertical knitting structures produced by knitting a chain stitch yarn continuously in the vertical direction while forming chain stitches, a vertical insertion yarn inserted into one needle in the vertical direction along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitting structures and binding adjacent knitting structures together,
A mesh-shaped fiber reinforced composite material obtained by forming the mesh-shaped knitted structure into a predetermined shape, and then impregnating only the knitting structure and the warp and weft insertion yarns in the mesh-shaped knitted structure with a resin and hardening the resin,
At least the warp insert yarns of the chain stitch yarns and the warp and weft insert yarns are carbon fiber strands made of carbon fiber,
The opening ratio of the mesh-like knitted structure is 20 to 60%.
A mesh-like fiber-reinforced composite material is provided.

According to one embodiment of the first and second present inventions, 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, or a polyetheretherketone resin; or a thermosetting resin such as a room temperature curing or thermosetting epoxy resin, a vinyl ester resin, an MMA resin, an acrylic resin, an unsaturated polyester resin, or a phenolic resin.

According to the third aspect of the present invention, there is provided a mesh-like knitted structure formed by a plurality of vertical knitting structures produced by knitting a chain stitch yarn continuously in the vertical direction while forming chain stitches, a vertical insertion yarn inserted vertically along one needle along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitting structures and binding adjacent knitting structures together,
A mesh-shaped fiber reinforced composite material in which only the knitted structure and the warp and weft insertion yarns in the mesh-shaped knitted structure are impregnated with a resin, hardened, and then shaped into a predetermined shape,
At least the warp insert yarns of the chain stitch yarns and the warp and weft insert yarns are carbon fiber strands made of carbon fiber,
The opening ratio of the mesh-like knitted structure is 20 to 60%.
A mesh-like fiber-reinforced composite material is provided.

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, or a polyetheretherketone resin.

According to one embodiment of the present invention, the weft insertion yarn is inserted at two, three, or four needles transversely to the vertical knitting structure, or the weft insertion yarn is inserted at two, three, or four needles transversely to the vertical knitting structure, and is arranged separately in front of and behind the vertical insertion yarn on the front and back of the knitted fabric. According to another embodiment, the weft insertion yarn is knitted at regular courses in the vertical knitting structure. According to yet another embodiment, the chain stitch yarn and the weft insertion yarn are yarns made from organic fibers such as polyester-based, polyamide-based, polyacrylonitrile-based, polyvinyl alcohol-based, and polyolefin-based fibers, and aramid fibers; metal fibers such as titanium fibers and steel fibers; and inorganic fibers such as carbon fibers and glass fibers; either alone or in combination with a plurality of types.

According to another embodiment of the present invention, the weft insertion yarns are arranged linearly in a transverse direction relative to the longitudinal knitting structure, and the weft insertion yarns are carbon fiber strands made of carbon fiber.

According to another embodiment of the present invention, the chain stitch yarn has a fineness of 10 to 600 dtex.

According to another embodiment of the present invention, the warp insertion yarns are
(a) A carbon fiber strand of PAN-based carbon fiber having 24,000 or less carbon fiber filaments and a fineness of 16,000 dtex or less, or
(b) A carbon fiber strand of pitch-based carbon fiber having 12,000 or less carbon fiber filaments and a fineness of 6,000 dtex or less.

According to another embodiment of the present invention, the weft insertion yarn has a fineness of 10 to 600 dtex, and is used in a state where 2 to 4 yarns are paralleled together, so that the total fineness is 700 to 2500 dtex.

According to the fourth aspect of the present invention, there is provided a mesh-like knitted structure formed by a plurality of vertical knitting structures produced by knitting a chain stitch yarn continuously in the vertical direction while forming chain stitches, a vertical insertion yarn inserted vertically along one needle along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitting structures and binding adjacent knitting structures together,
A mesh-shaped fiber-reinforced composite molding material is provided in which only the knitting structure and the warp and weft insertion yarns in the mesh-shaped knitted structure are impregnated with resin.

According to a fifth 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.

The mesh-like fiber-reinforced composite material of the present invention has excellent stretchability and drapeability, and is easily moldable into curved shapes. Furthermore, it has excellent breathability, preventing stuffiness, is lightweight, and has sufficient strength. It also has high rigidity and improved impact resistance. It is particularly suitable as a component constituting the basic structure of interior materials (innerwear) for hats, various protectors, and prosthetic limbs (artificial legs and artificial hands), or exterior materials (frames). Furthermore, the mesh-like fiber-reinforced composite material of the present invention can be suitably produced using the mesh-like fiber-reinforced composite molding material of the present invention. Furthermore, this mesh-like fiber-reinforced composite molding material can be suitably shaped to produce a mesh-like fiber-reinforced composite molded product of a desired shape.

FIG. 1 is a partial knitted structure diagram showing one embodiment of a mesh-like knitted structure used in the present invention. Figure 2(a) is a partially enlarged schematic diagram of the mesh-like knitted structure shown in Figure 1, and Figure 2(b) is a schematic cross-sectional diagram taken along line A-A in Figure 2(a), which illustrates the resin impregnation state of the mesh-like knitted structure. FIG. 3 is a diagram showing the structure of the mesh-like knitted structure shown in FIG. FIG. 4 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 5 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 6 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 7 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 8 is a diagram showing the structure of the mesh-like knitted structure shown in FIG. FIG. 9 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 10 is a diagram showing the structure of the mesh-like knitted structure shown in FIG. FIG. 11 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 12 is a partial knitted structure diagram showing an example of a conventional mesh-like knitted structure. FIG. 13 is a diagram showing the structure of the mesh-like knitted structure shown in FIG. FIG. 14 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 15 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 16 is a partial knitted structure diagram showing another embodiment of the mesh-like knitted structure used in the present invention. FIG. 17 is a diagram showing the structure of the mesh-like knitted structure shown in FIG. 18(a) to 18(e) are diagrams illustrating an embodiment of a method for forming a mesh-shaped fiber-reinforced composite material according to the present invention. 19(a) and 19(b) are diagrams illustrating another embodiment of the method for forming a mesh-shaped fiber-reinforced composite material according to the present invention. 20(a) and 20(b) are diagrams showing an example of a hat in which the mesh-shaped fiber-reinforced composite material of the present invention can be used as an inner material. FIG. 21(a) is a partial knitted structure diagram showing an example of a conventional mesh-like knitted structure, and FIG. 21(b) is a cross-sectional schematic diagram for explaining the resin impregnation state of the mesh-like knitted structure. 22(a) and 22(b) are partial plan views showing other examples of conventional mesh-like knitted structures. FIG. 23 is a schematic diagram of the mesh-like knitted structure shown in FIGS. 22(a) and 22(b). Figures 24(a) and (b) are diagrams explaining a test device for evaluating the drapeability of a mesh-like knitted structure, where Figure 24(a) is a photograph showing a picture frame jig showing the state in which a test piece of the mesh-like knitted structure is fixed, and Figure 24(b) is a diagram explaining the shape and dimensions of the test piece of the mesh-like knitted structure.

The mesh-like fiber-reinforced composite material , the material for molding the mesh-like fiber-reinforced composite material, and the mesh-like fiber-reinforced composite molded article according to the present invention will be described in more detail below with reference to the drawings.

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.

Example 1
An embodiment of a mesh-like fiber-reinforced composite material 10 according to the present invention will be described with reference to Figures 1, 2(a), 2(b), and 3. Figure 1 is a partially enlarged knitted structure diagram illustrating a mesh-like knitted structure, i.e., a mesh-like fiber sheet 1, which is a sheet-like reinforcing fiber knitted fabric, particularly a sheet-like reinforcing fiber warp knitted fabric, used in the present invention, and Figure 2(a) is a partially enlarged schematic diagram. Figure 2(b) is a cross-sectional schematic diagram taken along line A-A in Figure 2(a), illustrating the resin impregnation state of the mesh-like knitted structure. Figure 3 is a structure diagram of the mesh-like knitted structure 1 used in the present invention.

The mesh-shaped fiber reinforced composite material 10 according to the present invention is a mesh-shaped fiber reinforced composite material (FRP) obtained by impregnating and hardening each of the constituent yarns of the mesh-shaped knitted structure 1 shown in Fig. 1 with a resin R, as shown in Fig. 2(b). This mesh-shaped fiber reinforced composite material 10 is a molded product shaped into a predetermined shape (sometimes simply referred to as a "shape having a curved surface" or a "predetermined shape") having at least a curved surface region to form the basic structure of, for example, a hat as shown in Figs. 20(a) and 20(b), various protectors, interior materials (innerwear) for prosthetic limbs (prosthetic legs, prosthetic hands), or exterior materials (frames).

1, the mesh-like knitted structure 1 used in the present invention is characterized in that it is formed into a sheet shape by a plurality of knitted structures 20 (20a, 20b), i.e., double vertical knitted structures 20 (20a, 20b) of a front side knitted structure 20a and a back side knitted structure 20b, which are produced by knitting chain stitch yarns 2 (2a, 2b) in a loop shape continuously in the vertical direction and alternately forming chain stitches 2A on the front side and back side of the knitted fabric, i.e., double chain stitches 2A (2Aa, 2Ab) of a front side chain stitch 2Aa and a back side chain stitch 2Ab, a warp insertion yarn 5 inserted into one needle in the front side knitted structure 20a and the back side knitted structure 20b of the knitted structures 20 (20a, 20b), and a weft insertion yarn 3 inserted laterally in the vertical knitted structures 20 and binding adjacent knitted structures 20. Furthermore, at least the warp insertion yarns 5 use carbon fiber strands made of carbon fiber as reinforcing fibers. The chain stitch yarns 2 and the weft insert yarns 3 can be carbon fiber strands made of carbon fiber as the reinforcing fiber, like the warp insert yarns 5, but other reinforcing fibers can also be used. These reinforcing fibers will be described in detail later. The mesh-like knitted structure 1 can be formed in a sheet, web, or ribbon shape.

After or before the mesh-like knitted structure 1 is shaped into a predetermined shape, as described above with reference to Figures 2(a) and (b), resin R is impregnated only into the knitting structure 20 (20a, 20b) consisting of chain stitch yarns 2 (2a, 2b) in the mesh-like knitted structure 1, the vertical insertion yarns 5, and the horizontal insertion yarns 3. 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 knitting structure 20 (20a, 20b) consisting of the chain knitting yarns 2 (2a, 2b) in the mesh-like knitted structure 1 and the warp and weft inserted yarns 5, 3 are impregnated with resin R and hardened to form a mesh-like fiber reinforced composite material 10 of a predetermined shape; alternatively, the mesh-like knitted structure 1 is first impregnated with resin R only the knitting structure 20 (20a, 20b) and the warp and weft inserted yarns 5, 3 and hardened, and then heated and molded to form a mesh-like fiber reinforced composite material 10 formed into a predetermined shape.

In the mesh-like fiber reinforced composite material 10 according to the present invention, the mesh-like knitted structure 1 is a knitted fabric with loops extending three-dimensionally, so the fabric (mesh-like knitted structure 1) and its molded product (mesh-like fiber reinforced composite material 10) have a thickness that cannot be obtained with FRP materials molded using woven fabrics, and this thickness provides the rigidity of the molded product (FRP). On the other hand, in woven fabrics, the reinforcing fibers tend to flatten, and even after molding, the molding pressure causes the fibers to spread flat, resulting in a thin molded product and a lack of rigidity.

Generally, chain stitch yarns in a knitted fabric base material exist in the most stable curved shape within the knitted fabric, so high strength characteristics cannot be expected even when they are used as a fiber-reinforced composite material. However, in the present invention, for example, when shaping into a hemispherical shape, each chain stitch yarn, which is a reinforcing fiber, is hardened in a state in which it is stretched radially (in the stretching direction) from the apex of the hemisphere as it is shaped. Therefore, it exhibits high strength, especially against compression from the apex, and is ideal for molded products with curvature.

In particular, in the mesh-like fiber reinforced composite material 10 according to the present invention, the mesh-like knitted structure 1 has a plurality of double vertical knitted structures 20 (20a, 20b) of front side knitted structures 20a and back side knitted structures 20b, which are produced by knitting chain stitch yarns 2 (2a, 2b) in a continuous loop shape in the vertical direction to form double chain stitches 2A (2Aa, 2Ab) of front side chain stitches 2Aa and back side chain stitches 2Ab, and a single-needle vertical insertion yarn 5 is linearly inserted into the front side knitted structure 20a and the back side knitted structure 20b of the knitted structures 20 (20a, 20b), and this single-needle vertical insertion yarn 5 is a carbon fiber strand made of carbon fiber.

21(a) and 21(b) , the mesh-like knitted structure 1 used in the present invention has carbon fiber strands inserted as one-needle warp insertion yarns 5, and therefore has increased longitudinal strength and elastic modulus, thereby improving strength and impact resistance. Furthermore, the mesh-like knitted structure 1 used in the present invention has longitudinal knitted structures 20 (20a, 20b) consisting of a front side knitted structure 20a and a back side knitted structure 20b made on both sides of the knitted fabric, and the weft insertion yarns 3 binding these longitudinal knitted structures 20 (20a, 20b) together act as cushioning materials for the carbon fiber yarns that are one-needle warp insertion yarns 5, improving impact resistance.

The mesh-like fiber-reinforced composite material 10 constructed according to the present invention may have its elasticity restricted by the single-needle vertically inserted yarn 5 in the mesh-like knitted structure 1, and further by the thickening of the horizontally inserted yarn 3, as will be described in more detail below. However, because the mesh-like knitted structure 1 has a mesh structure that is easily shear deformable, it can be easily shaped into a three-dimensional shape, such as a hemisphere, and this does not pose a problem.

In the evaluation of drapeability using a picture frame jig according to the picture frame method, the mesh-like knitted structure used in the present invention preferably exhibits a load of 100 N or less, more preferably 50 N or less, measured when a displacement of 50 mm is applied in a direction at an angle of 45° to the longitudinal and transverse directions of the stitches. The smaller the measured load, the greater the deformation of the mesh-like knitted structure can be with a smaller force, making it easier to form it into a three-dimensional shape such as a hemisphere.

The evaluation of drapeability using a picture frame jig was carried out by fixing a mesh-like knitted structure (test piece 1T) cut into the shape shown in Figure 24(b) to a square metal jig 300 in which the distance between the fulcrums of each side (movable axes 301a to 301d) was 285 mm and the four corners were movable, as shown in Figure 24(a), and measuring the load measured when a displacement of 50 mm was applied in the tensile direction from the diagonal (45°) direction using a universal testing machine at a crosshead speed of 300 mm/min. The smaller the measured load, the easier the knitted structure was to deform.

Next, the mesh-like knitted structure 1 constituting the mesh-like fiber-reinforced composite material 10 of the present invention will be further described.

(Mesh-like knitted structure)
In this embodiment, the mesh-like knitted structure 1 is made of a knitting pattern 20 (20a, 20b), i.e., chain stitch yarns 2 (2a, 2b), weft insert yarns 3, and one needle warp insert yarn 5, and at least one needle warp insert yarn 5 uses a carbon fiber bundle (carbon fiber strand) made of carbon fiber as the reinforcing fiber. The chain stitch yarns 2 (2a, 2b) and the weft insert yarn 3 can also use carbon fiber bundles (carbon fiber strands), but in this embodiment, other reinforcing fibers are used. The reinforcing fibers that can be used for these chain stitch yarns 2 (2a, 2b) and the warp and weft insert yarns 5, 3 will be described in detail later.

According to this embodiment, the mesh-like knitted structure 1 has a double knitted structure 20 (20a, 20b) formed by arranging a large number of chain stitch yarns 2 (2a, 2b) in parallel while forming continuous loops in the vertical direction (the length direction of the fiber sheet), and a three-needle swing weft insertion yarn 3 is knitted into this knitted structure 20 (20a, 20b). In this embodiment shown in Figure 1, two parallel three-needle swing weft insertion yarns 3 cross every three yarns in the knitted structure 20 (20a, 20b) every course and reverse direction (the guide is swung by three needles every course), thereby forming a warp knitted fabric.

The mesh-like knitted structure 1 used in the present invention is not limited to the above-mentioned embodiment. The number of three-needle weft insertion yarns 3 is not limited to two, and four or other numbers of yarns may be used in a parallel arrangement.

In the embodiment shown in Fig. 1, the weft insert yarn 3 crosses every third knitted structure 20 (20a, 20b) in every course, reversing its direction (three needles inserted in every course) to form a warp knitted fabric, but other configurations are also possible. That is, in the embodiment shown in Fig. 4, the weft insert yarn 3 crosses every fourth knitted structure 20 (20a, 20b) in every course, reversing its direction (four needles inserted in every course), in the embodiment shown in Fig. 5, the insert yarn crosses every second knitted structure 20 (20a, 20b) in every third course, reversing its direction (two needles inserted in every three courses), and in the embodiment shown in Fig. 6, the weft insert yarn 3 crosses every second knitted structure 20 (20a, 20b) in every fourth course, alternating every two courses, reversing its direction (two needles inserted in every two courses, four courses) to form a warp knitted fabric.

In this embodiment, in the sheet-like mesh knitted structure (sheet material) 1, the chain stitch yarns 2 (2a, 2b) form loops, and the weft insertion yarns 3 are knitted into the loops and integrated. Therefore, when the sheet material is pulled in the length direction, for example, the loops stretch, and the arrangement angle of the weft insertion yarns 3 also changes accordingly, so the sheet material stretches easily and is highly stretchable and drapeable. This drapeability greatly determines the ability to form complex curved surfaces. Because the mesh knitted structure 1 has such excellent stretchability and drapeability, it can be formed into complex curved surfaces.

Furthermore, in the mesh-like knitted structure 1, the chain stitch yarns 2 (2a, 2b) form loops, and the weft insertion yarns 3 are also arranged in a folded form in the width direction, resulting in a multidirectional fiber arrangement overall, so that when made into a composite material (FRP) 10, it does not exhibit extreme anisotropy as in the forms of unidirectional materials or woven fabrics. Therefore, for example, when a plurality of mesh-like knitted structures 1 are stacked and used, pseudo-isotropic properties can be obtained even when multiple sheets are stacked in the same direction, without having to shape each sheet individually so that the fiber axes are different, and the molding process is extremely simplified.

In this embodiment, the mesh-like knitted structure 1 is a double Russell knitted fabric, in which chain stitch yarns 2 (2a, 2b) form vertical loops in a double knitted structure 20 (20a, 20b), and weft insertion yarns 3 are knitted into the loops and integrated, so the shape is stable and the fiber orientation is not disturbed during the layering process, which is preferable, but not limited to this. A single Russell knitted fabric is also acceptable, and there are many knitted structures, such as a chain stitch variation structure, a Denbigh structure, or a combination of a chain stitch structure and a Denbigh structure. These can be designed appropriately depending on the intended use and usage pattern.

Here, we will explain the one-needle warp insertion yarn 5 that is linearly inserted into the front knitted structure 20a and the back knitted structure 20b of the knitted structure 20 (20a, 20b). A flexible continuous carbon fiber strand is used as the warp insertion yarn 5. The carbon fiber strand 5 is formed by bundling a large number of continuous carbon fibers that are drawn parallel to one direction, and this fiber bundle forms the carbon fiber strand 5.

The carbon fiber used in this example is a PAN-based carbon fiber manufactured by heating a polyacrylonitrile fiber bundle in an oxygen atmosphere to oxidize and flame-retard the fiber bundle, and then carbonizing the resulting fiber bundle under tension in a high-temperature inert gas atmosphere. Therefore, although it depends on the processing conditions, the resulting carbon fiber has high strength and high elastic modulus, with a tensile strength of 3 to 10 GPa and a tensile modulus of 200 to 600 GPa, and exhibits uniform characteristics with little variation.

The number of filaments and the fineness of the continuous carbon fiber strands 5 used in this embodiment are 24,000 or less and 16,000 dtex or less, and may be, for example, about 18,000 or 12,000 dtex, but if the carbon fiber strands are too thick, the intersections of the chain stitch yarns 2 and the inserting yarns 3 will be thick, and there will also be voids in the knitted structure 20 where no carbon fibers are present, resulting in an FRP with large irregularities. Therefore, it is preferable that the number of filaments is 12,000 or less (for example, in the range of 3,000 to 12,000) and the fineness of the carbon fiber strands 5 is 8,000 dtex or less (for example, in the range of 2,000 to 8,000 dtex).

In the above description, PAN-based carbon fibers are used as the carbon fibers, but the PAN-based carbon fibers can be replaced in whole or in part with pitch-based carbon fibers. When pitch-based carbon fibers are used, the carbon fiber strands preferably have a carbon fiber filament count of 12,000 or less, preferably 3,000 to 6,000, and a fineness of 6,000 dtex or less, preferably 1,000 to 4,000 dtex. If the number of carbon fiber filaments exceeds 6,000 and the fineness exceeds 6,000 dtex, as described above, the carbon fiber strands become thicker and stronger, making it difficult to manufacture the mesh-like knitted structure 1 itself. This not only makes the intersections between the chain stitch yarn 2 and the warp and weft insertion yarns 5 and 3 thicker, but also results in a composite material 10 with large irregularities after resin impregnation, making it difficult to maintain high drapeability and stretchability.

In the above explanation, it has been explained that the mesh-like knitted structure 1 can use yarns made of carbon fiber strands for the chain stitch yarns 2 and the weft insert yarns 3 as well as the warp insert yarns, but it is not necessary for the entire mesh-like knitted structure 1 to be made of carbon fiber, that is, it is not necessary for all of the chain stitch yarns 2 and the weft insert yarns 3 constituting the mesh-like knitted structure 1 to be made of carbon fiber strands, and depending on the properties required of the mesh-like fiber reinforced composite material, i.e., strength, weight, etc., one of the chain stitch yarns 2 and the weft insert yarns 3, or some of the chain stitch yarns 2 and the weft insert yarns 3, which are used in combination, can be replaced with other fibers. In other words, in the present invention, at least the warp insert yarns 5 are carbon fiber strands made of carbon fiber, and the remaining yarns, i.e., the chain stitch yarns 2 and the weft insert yarns 3, can be made of fibers other than carbon fiber.

In this embodiment, fibers other than carbon fiber used for the chain stitch yarn 2 and the weft insert yarn 3 include, for example, organic fibers such as polyester, polyamide, polyacrylonitrile, polyvinyl alcohol, and polyolefin fibers, and aramid fibers; metal fibers such as titanium fibers and steel fibers; and inorganic fibers such as glass fibers; either alone or in combination. The chain stitch yarn 2 made from such fibers typically has a fineness of 10 to 600 dtex, preferably 30 to 300 dtex. If the fineness exceeds 600 dtex, the yarn becomes thicker, and the areas where the chain stitch yarn 2 intersects with the warp and weft insert yarns 5 and 3 become thicker, resulting in a composite material with significant irregularities after resin impregnation. It also becomes difficult to maintain high drapeability and stretchability. The weft insert yarns 3 typically have a fineness of 10 to 600 dtex, and are typically used in pairs of 2 to 4, with the total fineness of the weft insert yarns 3 being in the range of 700 to 2500 dtex. By using a thicker weft insert yarn 3, for example, 500 dtex x 2 (total fineness 1000 dtex) to 500 dtex x 4 (total fineness 2000 dtex), it is possible to obtain a composite with improved impact resistance after resin impregnation, without increasing the thickness of the areas where the chain stitch yarn 2 and the warp and weft insert yarns 5, 3 intersect.

In this embodiment, the reinforcing fiber weight per square meter of the mesh-like knitted structure 1 is preferably 100 to 700 g. When surface smoothness is required for the mesh-like fiber reinforced composite material 10, which is an FRP molding, it is preferable to use thin reinforcing fiber yarns and have a weight of 100 to 300 g/m ² , and when mechanical properties are required for the mesh-like fiber reinforced composite material 10 or when a thick mesh-like fiber reinforced composite material 10 is required, it is preferable to use thick reinforcing fiber yarns and have a weight of 300 to 700 g/m ² . Furthermore, if the basis weight is 100 g/ ^m2 or less, the knitted fabric (mesh-like knitted structure 1) will have large chain stitches 2A, resulting in more voids G and greater unevenness in the mesh-like fiber reinforced composite material 10. If the basis weight is 700 g/ ^m2 or more, the bending (crimping) of the carbon fiber strands will increase due to the crossing of the chain stitch yarns 2, 2 with each other and with the vertical and horizontal insertion yarns 5, 3, and stress concentration will reduce the mechanical properties of the mesh-like fiber reinforced composite material 10, which is undesirable.

In the mesh-like fiber-reinforced composite material 10 using the mesh-like knitted structure 1 of this embodiment, when an impact force is applied, the impact energy is first absorbed by the front knitted structure 20a and the back knitted structure 20b of the knitted structure 20 (20a, 20b) into which the vertical insertion yarns 5 are inserted, and the impact force is alleviated. As a result, unlike the composite material using the fiber sheet 1B described in Patent Document 4 (Japanese Patent No. 4,463,657) described above with reference to Figures 22 and 23, no large load is applied to the carbon fibers 50, which are made into a unidirectional material with straight alignment, and the carbon fibers are prevented from breaking, resulting in an FRP molded product with high impact resistance.

Furthermore, the mesh-like knitted structure 1A used in the mesh-like fiber-reinforced composite material 10A described in Patent Document 3 (Japanese Patent No. 6,362,454) shown in Figures 21(a) and (b) has excellent stretchability and drapeability, as described above, and is excellent in terms of formability into shapes having curved surfaces. However, because of its stretchability, when the mesh-like fiber-reinforced composite material is impregnated with resin and hardened, i.e., when it is made into an FRP structure, there is a problem in that it can be broken from the resin by a slight external force.

In order to further improve the impact resistance of the FRP in the mesh-shaped fiber-reinforced composite material 10 of the present invention, it is preferable to use a resin with high breaking elongation so as to increase the impact energy absorbed in the resin portion. In the case of thermoplastic resins, thermoplastic epoxy resins, phenoxy resins, polycarbonate resins, polyester resins, polyurethane resins, polyamide resins, polyetherimide resins, and polyether ether ketone resins are preferred, and in the case of thermosetting resins, high breaking elongation resins with a breaking elongation of 4% or more, such as room temperature curing or thermosetting epoxy resins, vinyl ester resins, MMA resins, acrylic resins, unsaturated polyester resins, and phenolic resins are preferred.

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.

The mesh-like knitted structure 1 can be suitably produced using a Russell knitting machine, particularly by adopting the method for producing a sheet-like carbon fiber knitted fabric described in Patent Document 2 (Japanese Patent No. 4822528), and can also be knitted using a tricot knitting machine, a crochet knitting machine, etc. Such knitted fabric production methods are well known to those skilled in the art, and therefore further detailed explanations thereof will be omitted.

(Opening ratio)
In the present invention, the opening rate 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 rate is set to 20 to 60%, preferably 20 to 50%, and more preferably 30 to 50%.

According to the present invention, the mesh-like knitted structure 1 is impregnated with resin R only into the knitted structure 20 formed by the chain stitch yarn 2 and the warp and weft insertion yarns 5, 3 in the mesh-like knitted structure 1, and then hardened.In other words, the resin is not filled into 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.

The open area ratio generally refers to 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 refers to 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 portions with and without fibers is calculated. In practice, the mesh knitted structure 1 is scanned with a two-dimensional scanner, and the open area ratio is calculated by dividing it into void portions and fiber portions using image software. For example, such an open area ratio can be efficiently determined using a two-dimensional scanner (trade name "CanoScan 4400F") manufactured by Canon Inc.
Opening rate (%) = {(area of void portion) / (area of fiber portion + area of void portion)} × 100

As described above, in the present invention, the opening rate of the mesh-like knitted structure 1 is set to 20 to 60%. If the opening rate 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 rate 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 rate is set to 20 to 50%, more preferably 30 to 50%.

In the present invention, the size of each opening (hole) in the mesh-like knitted structure 1 is also important, and it is important that the area of each opening is 1.5 to 80 mm ^2. If the area of each opening is less than 1.5 mm ² , there is a possibility that no holes will be formed during molding, and if the area of each opening exceeds 80 mm ² , the mesh after molding will be too large, and there is a possibility that the rigidity of the mesh-like fiber-reinforced composite material 10 will be lost.

(Impregnated resin)
In the present invention, 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 5, 3 in the mesh-like knitted structure 1 are impregnated with a resin R and hardened to form a 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.

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

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

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.

18(a) to 18(e) 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. 18(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.

Next, resin R is applied to the mesh-like knitted structure 1 using an impregnation brush or the like to impregnate only the knitted structure 20 (20a, 20b) consisting of the chain stitch yarns 2 (2a, 2b) of the mesh-like knitted structure 1 and the warp and weft insertion yarns 5, 3 with the resin (FIG. 18(b)). The resin R may be a thermosetting resin or a thermoplastic resin. A concave female mold 202 is then fitted to the male mold 201, and the resin 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. 18(c)). The mesh-like fiber-reinforced composite material 10 is then removed from the mold (FIG. 18(d)) and finished into the predetermined shape (FIG. 18(e)).

19(a) and (b) show a vacuum forming method, which is another example of a molding method. According to this vacuum forming method, the mesh-like knitted structure 1 is formed by impregnating and curing only the knitted structure 20 made of chain stitch yarns 2 and the warp and weft insertion yarns 5, 3 with resin, forming a flat mesh-like knitted structure 1a made of FRP material. Although thermosetting resins can also be used in a B-stage state, thermoplastic resins are preferably used. The mesh-like knitted structure 1 may be impregnated with resin in advance or immediately before molding.

The mesh-like knitted structure 1, which has been impregnated with and cured with resin, is placed on a concave vacuum mold (female mold) 202 as a mesh-like fiber-reinforced composite molding material 1a and is further covered with a resin film 60 (FIG. 19(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 that has impregnated and cured 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. 19(b)). Thereafter, as with 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. 18(d) and 18(e) .

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

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

Example 2
Another embodiment of the mesh-like fiber reinforced composite material 10 according to the present invention will be described with reference to Figures 7 and 8. Figure 7 is a partially enlarged knitting structure diagram for explaining the sheet-like reinforcing fiber knitted fabric, i.e., the mesh-like knitted structure that is a sheet-like reinforcing fiber warp knitted fabric, i.e., the mesh-like fiber sheet 1, used in this embodiment, and Figure 8 is a diagram showing the structure of the mesh-like knitted structure of this embodiment.

The mesh-shaped fiber-reinforced composite material 10 of this embodiment is produced by impregnating each constituent yarn of the mesh-shaped knitted structure 1 shown in Figure 7 with resin R and curing it, in the same manner as described in Example 1, with reference to Figures 2(a) and (b).

The mesh-like knitted structure 1 of this embodiment, as described in Example 1, has a plurality of knitted structures 20 produced by knitting chain stitch yarns 2 (2a, 2b) in a continuous vertical loop shape, and alternating between the front and back of the knitted fabric to form chain stitches 2A, i.e., double chain stitches 2A (2Aa, 2Ab) of front side chain stitches 2Aa and back side chain stitches 2Ab, i.e., double vertical knitted structures 20 (20a, 20b) of front side knitted structure 20a and back side knitted structure 20b, and a vertical insertion yarn 5 inserted into one needle in the front side knitted structure 20a and back side knitted structure 20b of the knitted structure 20 (20a, 20b).

Here, as shown in Figures 1 and 4 to 6, the mesh-like knitted structure 1 of Example 1 is configured so that the horizontal insertion yarns 3 forming the horizontal insertion structure are inserted horizontally, for example, by two, three, or four needles, relative to the vertical knitted structure 20, and adjacent knitted structures 20 are bound together to form a sheet.

In contrast to this, in this Example 2, as shown in Figures 7 and 8, the two or four weft insert yarns 3 (3a, 3b) are arranged transversely to the vertical knitting structure 20 (in this Example, they are inserted and arranged with three needles, but they can also be inserted and arranged with two or four needles), and the weft insert yarns 3 are separated into weft insert yarns 3a and 3b, which are separated in front and behind the vertical insert yarns 5 and are arranged on the front and back sides of the knitted fabric as front side insert yarns 3a and back side insert yarns 3b, respectively. The mesh-like knitted structure 1 of this Example 2 is characterized in that the front and back of the knitted fabric are the same (mirror symmetry).

In this Example 2, at least the warp insert yarns 5 are made of carbon fiber strands as reinforcing fibers. The chain stitch yarns 2 and the weft insert yarns 3 (3a, 3b) can be made of carbon fiber strands as reinforcing fibers, like the warp insert yarns 5, but other reinforcing fibers can also be used. These reinforcing fibers are as described in Example 1, and will not be described again here.

After or before shaping the mesh-like knitted structure 1 into a predetermined shape, as described above in Example 1, resin R is impregnated only into the knitted structure 20 (20a, 20b) consisting of chain stitch yarns 2 (2a, 2b), the vertical insertion yarns 5, and the horizontal insertion yarns 3 (3a, 3b) in the mesh-like knitted structure 1.

The mesh-shaped fiber-reinforced composite material 10 of Example 2 can also achieve the same effects as the mesh-shaped fiber-reinforced composite material 10 of Example 1. That is, as understood above, the mesh-shaped fiber-reinforced composite material 10 of Example 2 formed as described above has one carbon fiber yarn inserted vertically per needle, thereby increasing the longitudinal strength and elastic modulus. Furthermore, the chain stitch yarns 2 (2a, 2b) forming the stitches on both sides of the knitted fabric and the two or four parallel two-, three-, or four-needle weft-inserted yarns 3 (3a, 3b) act as cushioning materials for the carbon fiber yarn of the one-needle vertical-inserted yarn 5, improving impact resistance. Furthermore, even if stretchability is suppressed by the insertion of the one-needle vertical-inserted yarn 5 or by the thickening of the weft-inserted yarns 3 (3a, 3b), the mesh structure is easily shear-deformable, so it is easy to mold (shape) into three-dimensional shapes such as hemispheres.

Example 3
Another embodiment of the mesh-like fiber reinforced composite material 10 according to the present invention will be described with reference to Figures 9 and 10. Figure 9 is a partially enlarged knitted structure diagram for explaining the sheet-like reinforcing fiber knitted fabric, i.e., the mesh-like knitted structure that is a sheet-like reinforcing fiber warp knitted fabric, i.e., the mesh-like fiber sheet 1, used in this embodiment, and Figure 10 is a diagram showing the structure of the mesh-like knitted structure 1 of this embodiment.

The mesh-shaped fiber-reinforced composite material 10 of this embodiment is produced by impregnating each constituent yarn of the mesh-shaped knitted structure shown in Figure 9 with resin R and curing it, in the same manner as described in Example 1, with reference to Figures 2(a) and (b).

As shown in Figure 9, the mesh-like knitted structure 1 of this embodiment, as described in Example 1, has a plurality of knitted structures 20 made by knitting chain stitches 2 (2a, 2b) in a continuous vertical loop shape, and forming chain stitches 2A alternately on the front and back of the knitted fabric, i.e., double chain stitches 2A (2Aa, 2Ab) of front side chain stitches 2Aa and back side chain stitches 2Ab, i.e., double vertical knitted structures 20 (20a, 20b) of front side knitted structure 20a and back side knitted structure 20b, and a vertical insertion yarn 5 inserted into one needle in the front side knitted structure 20a and back side knitted structure 20b of the knitted structure 20 (20a, 20b).

Here, as shown in Figures 1 and 4 to 6, the mesh-like knitted structure 1 of Example 1 is configured so that the horizontal insertion yarns 3 forming the horizontal insertion structure are inserted horizontally, for example, by two, three, or four needles, relative to the vertical knitted structure 20, and adjacent knitted structures 20 are bound together to form a sheet.

In contrast, in Example 3, as shown in Figures 9 and 10, the weft insertion yarns 3 are arranged linearly in the transverse direction relative to the vertical knitting structure 20. In Example 3, the weft insertion yarns 3, together with the vertical insertion yarns 5, use carbon fiber strands made of carbon fiber as reinforcing fibers. The chain stitch yarns 2 (2a, 2b) can be carbon fiber strands made of carbon fiber as reinforcing fibers, like the weft insertion yarns 3 and the vertical insertion yarns 5, but other reinforcing fibers can also be used. These reinforcing fibers are as described in Example 1, and will not be described again here.

After or before shaping the mesh-like knitted structure 1 into a predetermined shape, as described above in Example 1, resin R is impregnated only into the knitted structure 20 (20a, 20b) consisting of chain stitch yarns 2 (2a, 2b) in the mesh-like knitted structure 1, the vertical insertion yarns 5, and the horizontal insertion yarns 3.

In the mesh-shaped fiber-reinforced composite material 10 of Example 3, the carbon fiber thread is inserted vertically with one needle and linearly in the horizontal direction, so the strength and elastic modulus are increased in both the vertical and horizontal directions. On the other hand, the shapeability is slightly inferior to that of Examples 1 and 2 above, but the mesh structure provides shear strength, and there are no problems with formability (shapeability) into three-dimensional shapes such as hemispheres.

(Experimental Examples 1 to 9, Comparative Examples 1 to 5)
Next, to verify the effects of the mesh-like fiber-reinforced composite material 10 and mesh-like knitted structure 1 according to the present invention, fabrics were knitted while changing the types and opening ratios of the chain stitch yarns 2, warp insertion yarns 5, and weft insertion yarns 3 of the mesh-like knitted structure 1, and the fabrics were impregnated with resin and molded to produce mesh-like fiber-reinforced composite materials 10, which were then subjected to various evaluations. The experimental results are shown in Table 1. In the experimental examples and comparative examples, the fiber content in the composite material was 65% by weight.

Experimental Example 1
As shown in the mesh-like knitting structure and knitting structure diagram of Example 1 described with reference to Figures 1 to 3, a Karl Mayer HDR8EH-S 6-gauge double Russell warp knitting machine was used, and chain stitches 2A were formed alternately on the front and back sides of the chain stitch structure 20 using Vinylon 500T-200 (fineness: 500 dtex) manufactured by Kuraray Co., Ltd. as the chain stitch yarn 2. At the same time, carbon fiber yarn TR50S-12L-AL (fineness: 8000 dtex) manufactured by Mitsubishi Chemical Corporation was used as the warp insert yarn 5 with one swing, and two Vinylon 500T-200 used as the chain stitch yarn 2 were aligned as the weft insert yarn 3 with three swing needles, resulting in a total fineness of 1000 dtex, which were supplied to each guide hole of the knitting machine, and knitting was performed with a width of 40 cm and a course density of 9.5 stitches/25.4 mm.

The obtained knitted fabric had a basis weight (actual mass) of 372 g/ ^m2 , a thickness of 1.50 mm, an opening ratio of 43.8%, and an area of each opening (hole) of 4.96 ^mm2.The carbon fiber yarns with a high tensile modulus were arranged in the length direction of the knitted fabric, resulting in a knitted fabric with almost no stretch, but a mesh structure that easily stretched in diagonal directions.

Next, the knitted fabric was impregnated with a thermoplastic epoxy resin (trade name "XNR6850V" manufactured by Nagase ChemteX Corporation), and then the solvent was dried in an oven at 120°C for 10 minutes, followed by heating at 160°C for 30 minutes to obtain a flat plate.

The mesh-like fiber reinforced composite material 10 was subjected to a punching impact strength test (drop mass: 1.59 kg, drop height: 580 mm, striker: 20 mm hemispherical) using an Instron universal testing machine "CEAST9310." The load cell capacity was 10 kN (upper design limit 5 kN), and the impact energy (potential energy) was 9.03 J. The results are shown in Table 1. In Table 1, "Peak Force" is the maximum load in the impact test, and "Total Energy" is the area of the displacement-load curve in the impact test. "Peak Force/design 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.

In addition, flat test pieces of the mesh-like fiber-reinforced composite material 10 were prepared with the longitudinal direction or the transverse direction as the long side, with the longitudinal direction (vertical, 0°) being the direction when the auxiliary yarns (warp/chain knit) of the mesh-like fiber-reinforced composite material 10 were connected in the longitudinal direction of the test piece, and the transverse direction (horizontal, 90°) being the direction when the auxiliary yarns were connected in the width direction of the test piece, and the tensile strength was measured using a universal testing machine "RTF-2410" manufactured by AND Co., Ltd. in accordance with JIS K 7164 (Testing methods for tensile properties of plastics).

Experimental Example 2
In Experimental Example 1, two weft insertion yarns 3a and 3b, which were made of aligned vinylon 500T-200 and supplied as three-needle weft insertion yarns 3, were inserted separately so that one was positioned above and one was positioned above the carbon fiber yarn inserted vertically through one needle in the thickness direction of the knitted fabric, as shown in the mesh-like knitting structure and knitting structure diagram shown in Example 2 described with reference to Figures 7 and 8. Knitting was carried out under the same conditions as in Experimental Example 1.

The obtained knitted fabric had a basis weight of 426 g/ ^m2 , a thickness of 1.58 mm, an opening ratio of 44.1%, and an area of each opening (hole) of 5.00 ^mm2.As with Experimental Example 1, the knitted fabric had almost no stretch in the longitudinal direction of the fabric, but had a mesh structure that was easily stretchable in diagonal directions.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 3
In Experimental Example 1, two insert yarns of Vinylon 500T-200 were paralleled and supplied as the three-needle weft insert yarn 3, but this was increased to four, and the yarns were paralleled and supplied to a total fineness of 2000 dtex, and knitting was carried out under the same conditions as in Experimental Example 1.

The obtained knitted fabric had a basis weight of 445 g/ ^m2 , a thickness of 1.82 mm, an opening ratio of 24.8%, and an area of each opening (hole) of 2.78 mm2.Similar to Experimental Examples 1 and ² , the knitted fabric had almost no stretch in the longitudinal direction of the fabric, but had a mesh structure that easily stretched in diagonal directions.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 4
In Experimental Example 3, the Vinylon 500T-200 yarn used for the chain stitch yarn 2 and the four aligned three-needle swing weft insertion yarns 3 was changed to polyester filament yarn PET560T-96-P703B (fineness: 560 dtex) manufactured by Teijin Ltd. (total fineness of weft insertion yarns: 2240 dtex), except that the knitting was carried out under the same conditions as in Experimental Example 3.

The obtained knitted fabric had a basis weight of 507 g/ ^m2 , a thickness of 1.70 mm, an opening ratio of 26.0%, and an area of each opening (hole) of 2.91 mm2.Similar to Experimental Examples 1 and ² , the knitted fabric had almost no stretch in the longitudinal direction of the fabric, but had a mesh structure that easily stretched in diagonal directions.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 5
In Experimental Example 2, knitting was performed under the same conditions as in Experimental Example 2, except that two vinylon 500T-200 yarns 3a and 3b were weft-inserted horizontally in three swing needles above and below the carbon fiber yarn inserted vertically in one swing needle, and two of each yarn were paralleled together to increase the number of yarns to a total of four (total fineness of the weft-inserted yarns: 2000 dtex).

The obtained knitted fabric had a basis weight of 483 g/ ^m2 , a thickness of 1.70 mm, an opening ratio of 25.2%, and an area of each opening (hole) of 2.82 mm2.Similar to Experimental Examples 1 and ² , the knitted fabric had almost no stretch in the longitudinal direction of the fabric, but had a mesh structure that was easily stretchable in diagonal directions.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 6
The knitting was carried out under the same conditions as in Experimental Example 5, except that the chain stitch yarn 2 used in Experimental Example 5 and the two vinylon 500T-200 yarns used as the three-needle horizontally inserted yarns 3a and 3b were changed to polyester filament yarn PET560T-96-P703B (fineness: 560 dtex) (total fineness of the horizontally inserted yarns: 2240 dtex).

The obtained knitted fabric had a basis weight of 533 g/ ^m2 , a thickness of 1.65 mm, an opening ratio of 26.2%, and an area of each opening (hole) of 2.94 ^mm2.As with Experimental Example 5, the knitted fabric had almost no stretch in the longitudinal direction of the fabric, but had a mesh structure that was easily stretchable in diagonal directions.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 7
Knitting was carried out under the same conditions as in Experimental Example 1, except that the course density, which was a knitting requirement of Experimental Example 1, of 9.5 threads/25.4 mm was increased to 15.0 threads/25.4 mm.

The resulting knitted fabric had a basis weight of 426 g/ ^m2 , a thickness of 1.85 mm, an opening ratio of 21.1%, and an area of each opening (hole) of 1.52 ^mm2.Compared to the knitted fabric of Experimental Example 1, the course density was increased and the area of the openings was reduced, resulting in a mesh structure with lower diagonal extensibility than Experimental Example 1.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 8
As shown in the mesh-like knit structure and knitting structure diagram shown in Example 3 described with reference to Figures 9 and 10, polyester filament yarn PET560T-96-P703B (fineness: 560 dtex) was used as the chain stitch yarn 2, and chain stitches 2A were formed alternately on the front and back sides of the chain stitch structure 20 in the same manner as in Experimental Example 1. At the same time, carbon fiber yarn TR50S-12L-AL (fineness: 8000 dtex) manufactured by Mitsubishi Chemical Corporation was used as the one-needle warp insertion yarn 5, and the same carbon fiber yarn as the one-needle warp insertion yarn 5 was inserted linearly as the weft insertion yarn 3 between the front and back stitches for each course across the entire width in the width direction of the knitted fabric, and knitting was performed with a width of 40 cm and a course density of 9.5 stitches/25.4 mm as in Experimental Example 1.

The resulting knitted fabric had a basis weight of 467 g/ ^m2 , a thickness of 1.25 mm, an opening ratio of 21.1%, and an area of each opening (hole) of 2.39 ^mm2.Since continuous highly elastic carbon fiber yarns were inserted in the length and width directions of the knitted fabric, the mesh structure was almost inelastic in both directions but easily stretched in diagonal directions.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Experimental Example 9
Knitting was performed under the same conditions as in Experimental Example 8, except that the carbon fiber yarns (weftly inserted yarns 3) inserted laterally continuously in every course in the width direction were inserted every two courses (1 in 1 out) as shown in the knitting pattern of Fig. 11 .

The resulting knitted fabric had a basis weight of 471 g/ ^m2 , a thickness of 1.57 mm, an opening rate of 57.4%, and an area of each opening (hole) of 6.5 ^mm2.Like Experimental Example 8, the knitted fabric had almost no stretch in the length and width directions, but due to its large opening rate, it had a mesh structure that was more easily stretched in diagonal directions than the knitted fabric of Experimental Example 8.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Comparative Example 1
Comparative Example 1 is a knitted fabric similar to the mesh-shaped fiber-reinforced composite material described in the above Patent Document 3 (Japanese Patent No. 6,362,454), and is intended for comparison with the mesh-shaped fiber-reinforced composite material 10 of the present invention. In this comparative example, the same double Russell warp knitting machine used in the above experimental examples was used, and in the knitting structure and knitting texture diagrams shown in Figures 12 and 13, the chain stitch yarn 2 was the same vinylon 500T-200 (fineness: 500 dtex) as used in Experimental Example 1, and the two-needle swing weft insertion yarn 3 was the carbon fiber yarn TR50S-12L-AL (fineness: 8,000 dtex) as used in Experimental Example 1, and the knitting was set to a width of 40 cm and a course density of 9.5 threads/25.4 mm.

The obtained knitted fabric had a basis weight of 550 g/ ^m2 , a thickness of 1.50 mm, an opening ratio of 55.0%, and an area of each opening (hole) of 6.04 ^mm2 , and had a mesh structure that was stretchable in both the length and width directions of the knitted fabric.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Comparative Example 2
In Comparative Example 2, the knitted fabric of Experimental Example 1 was knitted under the same conditions as Experimental Example 1, except that one vinylon 500T-200 (fineness: 500 dtex) was used as the weft insertion yarn 3 and the weft insertion structure was changed to a two-needle swing, as shown in Figure 14.

The obtained knitted fabric had a basis weight of 347 g/ ^m2 , a thickness of 1.40 mm, an opening ratio of 45.2%, and an area of each opening (hole) of 5.03 ^mm2 . Similar to the knitted fabric in Experimental Example 1, the knitted fabric had almost no stretch in the length direction, but because it was a two-needle swing horizontal insertion structure, it had a mesh structure that easily stretched in the width direction.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Comparative Example 3
The knitted fabric of Comparative Example 3 was knitted under the same conditions as the knitted fabric of Comparative Example 2, except that the carbon fiber yarn used as the one-needle warp insertion yarn 5 and the vinylon yarn used as the two-needle weft insertion yarn 3 were interchanged.

The resulting knitted fabric had a basis weight of 568 g/ ^m2 , a thickness of 1.70 mm, an opening ratio of 40.5%, and an area of each opening (hole) of 4.85 ^mm2 . As with Comparative Example 2, the knitted fabric had almost no stretch in the length direction, as with the knitted fabric of Experimental Example 1, but because it was a two-needle swing horizontal insertion structure, it had a mesh structure that easily stretched in the width direction.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Comparative Example 4
The knitted fabric of Comparative Example 4 was knitted under the same conditions as Comparative Example 2, except that the swing width of the weft insertion yarn 3 in the knitted fabric of Comparative Example 2 was changed from two-needle swing to three-needle swing, as shown in FIG.

The obtained knitted fabric had a basis weight of 324 g/ ^m2 , a thickness of 1.35 mm, an opening ratio of 51.3%, and an area of each opening (hole) of 5.70 ^mm2.Since the carbon fibers were inserted vertically in the length direction of the knitted fabric with one needle swing, the mesh structure had almost no stretch, similar to Comparative Example 2, and stretched slightly in the width direction.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

Comparative Example 5
The knitted fabric of Comparative Example 5 has the mesh-like knitting structure and knitting structure diagram shown in Figs. 16 and 17, and was knitted under the same conditions as Comparative Example 2 except that the swing width was changed to four needles.

The obtained knitted fabric had a basis weight of 339 g/ ^m2 , a thickness of 1.45 mm, an opening ratio of 40.6%, and an area of each opening (hole) of 4.60 ^mm2 , and had a mesh structure with less stretch in the width direction than the knitted fabric of Comparative Example 4 using three-needle horizontal insertion yarn 3.

Next, a mesh-like fiber-reinforced composite material 10 was produced in the same manner as in Experimental Example 1, and a punching impact strength test was carried out. The results are shown in Table 1.

(Consideration)
The above experimental examples and comparative examples demonstrate that high tensile strength and impact strength can be imparted to a mesh knitted structure by inserting high-strength, high-elasticity carbon fiber yarns in the longitudinal or transverse direction. This high impact strength is thought to be due in particular to the fact that the continuously arranged carbon fibers respond quickly to impacts and absorb the impact energy. However, because continuously arranged carbon fibers are restricted in their movement during press molding, this may be detrimental to formability. However, this is limited to cases where particularly large formability is required, and can be addressed by selecting the specifications of the knitted structure depending on the application.

On the other hand, it was confirmed that by placing thick knitted yarn or inserted yarn made of synthetic fiber around the carbon fiber yarn as a cushioning material, the carbon fiber is protected and a mesh-shaped fiber-reinforced composite material with high impact resistance can be obtained.

Furthermore, from Experimental Examples 1 to 9 and Comparative Examples 2, 4, and 5, it was found that by using thick fineness weft-inserted yarns, the impact resistance after resin impregnation was improved.

The porous structure of the present invention is particularly suitable as an interior/exterior component for protectors such as protective helmets and prosthetic limbs (prosthetic legs and prosthetic hands), but its applications are not limited thereto. For example, it can be used in a wide range of industrial and consumer applications, including medical materials 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, and structural reinforcing components, as well as structural and decorative components for aircraft, rockets, artificial satellites, automobiles, motorcycles, trains, bicycles, houses, optical equipment, home appliances, and portable electronic devices, which require molding and processing into complex curved shapes while maintaining high rigidity.

REFERENCE SIGNS LIST 1 Mesh-shaped knitted structure 1a Mesh-shaped fiber-reinforced composite molding material 2 (2a, 2b) Chain stitch yarn 2A Chain stitch 3 (3a, 3b) Horizontal insertion yarn 5 Warp insertion yarn 10 Mesh-shaped fiber-reinforced composite material 20 Knitted structure

Claims (15)

The knitted structure has a mesh-like knitted structure formed by a plurality of vertical knitted structures produced by knitting chain stitches while continuous chain stitch yarns are formed in the vertical direction, a vertical insertion yarn inserted into one needle in the vertical direction along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitted structures to bind adjacent knitted structures together,
A mesh-shaped fiber reinforced composite material in which only the knitting structure and the warp and weft insertion yarns in the mesh-shaped knitted structure are impregnated with a resin and hardened,
At least the warp insert yarns of the chain stitch yarns and the warp and weft insert yarns are carbon fiber strands made of carbon fiber,
The opening ratio of the mesh-like knitted structure is 20 to 60%.
A mesh-like fiber-reinforced composite material characterized by: The knitted structure has a mesh-like knitted structure formed by a plurality of vertical knitted structures produced by knitting chain stitches while continuous chain stitch yarns are formed in the vertical direction, a vertical insertion yarn inserted into one needle in the vertical direction along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitted structures to bind adjacent knitted structures together,
A mesh-shaped fiber reinforced composite material obtained by forming the mesh-shaped knitted structure into a predetermined shape, and then impregnating only the knitting structure and the warp and weft insertion yarns in the mesh-shaped knitted structure with a resin and hardening the resin,
At least the warp insert yarns of the chain stitch yarns and the warp and weft insert yarns are carbon fiber strands made of carbon fiber,
The opening ratio of the mesh-like knitted structure is 20 to 60%.
A mesh-like fiber-reinforced composite material characterized by: 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 thermoplastic resin such as a thermoplastic epoxy resin, phenoxy resin, polycarbonate resin, polyester resin, polyurethane resin, polyamide resin, polyetherimide resin, or polyetheretherketone resin; or 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. The knitted structure has a mesh-like knitted structure formed by a plurality of vertical knitted structures produced by knitting chain stitches while continuous chain stitch yarns are formed in the vertical direction, a vertical insertion yarn inserted into one needle in the vertical direction along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitted structures to bind adjacent knitted structures together,
A mesh-shaped fiber reinforced composite material in which only the knitted structure and the warp and weft insertion yarns in the mesh-shaped knitted structure are impregnated with a resin, hardened, and then shaped into a predetermined shape,
At least the warp insert yarns of the chain stitch yarns and the warp and weft insert yarns are carbon fiber strands made of carbon fiber,
The opening ratio of the mesh-like knitted structure is 20 to 60%.
A mesh-like fiber-reinforced composite material characterized by: The mesh-shaped fiber-reinforced composite material described in claim 4, characterized in that the resin impregnated into the mesh-shaped knitted structure is a thermoplastic resin such as thermoplastic epoxy resin, phenoxy resin, polycarbonate resin, polyester resin, polyurethane resin, polyamide resin, polyetherimide resin, or polyether ether ketone resin. A mesh-shaped fiber-reinforced composite material according to any one of claims 1 to 5, characterized in that the weft-inserted yarns are arranged in two, three, or four needles inserted transversely to the vertical knitting structure. A mesh-shaped fiber-reinforced composite material according to any one of claims 1 to 5, characterized in that the weft-inserted yarns are inserted horizontally into the vertical knitting structure by two, three, or four needles, and are arranged on the front and back of the knitted fabric, separated in front of and behind the vertical-inserted yarns. A mesh-shaped fiber-reinforced composite material as described in claim 6 or 7, characterized in that the weft-inserted yarns are woven into the vertical knitting structure at regular intervals. The mesh-shaped fiber-reinforced composite material according to any one of claims 1 to 8, characterized in that the chain knitting yarns and the weft insertion yarns are made from organic fibers such as polyester, polyamide, polyacrylonitrile, polyvinyl alcohol, and polyolefin fibers, and aramid fibers; metal fibers such as titanium and steel fibers; and inorganic fibers such as carbon and glass fibers, either alone or in combination. A mesh-shaped fiber-reinforced composite material according to any one of claims 1 to 5, characterized in that the weft insertion yarns are arranged linearly in the transverse direction relative to the longitudinal knitting structure, and the weft insertion yarns are carbon fiber strands made of carbon fiber. A mesh-shaped fiber-reinforced composite material according to any one of claims 1 to 10, characterized in that the chain stitch yarn has a fineness of 10 to 600 dtex. The warp insertion yarns are
(a) A carbon fiber strand of PAN-based carbon fiber having 24,000 or less carbon fiber filaments and a fineness of 16,000 dtex or less, or
(b) A carbon fiber strand made of pitch-based carbon fiber having 12,000 or less carbon fiber filaments and a fineness of 6,000 dtex or less.
12. The mesh-like fiber-reinforced composite material according to claim 1. A mesh-shaped fiber-reinforced composite material according to any one of claims 1 to 12, characterized in that the weft-inserted yarns have a fineness of 10 to 600 dtex, are used in pairs of 2 to 4, and have a total fineness of 700 to 2500 dtex. The knitted structure has a mesh-like knitted structure formed by a plurality of vertical knitted structures produced by knitting chain stitches while continuous chain stitch yarns are formed in the vertical direction, a vertical insertion yarn inserted into one needle in the vertical direction along the chain stitches, and a horizontal insertion yarn inserted horizontally into the vertical knitted structures to bind adjacent knitted structures together,
A mesh-shaped fiber-reinforced composite molding material in which only the knitting structure and the warp and weft insertion yarns in the mesh-shaped knitted structure are impregnated with resin. A mesh-shaped fiber-reinforced composite molding obtained by shaping the mesh-shaped fiber-reinforced composite molding material according to claim 14 .