JP2004036055A - Fibrous structural material and composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the production of a fiber-reinforced composite material having a high strength by using a continuous fiber at a low cost. <P>SOLUTION: This fibrous structural material 1 is equipped with a laminated fiber group 2 formed by orienting fiber bundles consisting of the continuous fiber biaxially and thickness directional yarn 3 oriented in the thickness direction for binding the laminated fiber group 2, and formed as a board shape. The laminated fiber group 2 is constituted by laminating alternately an x-yarn layer 4 consisting of the x-yarn 4a as the fiber bundle oriented in a plane crossing to the thickness direction of the fibrous structural material 1 and a y-yarn layer 5 consisting of the y-yarn 5a as the fiber bundle oriented in a plane crossing to the thickness direction of the fibrous structural material in a state of crossing to the x-yarn 4a. The thickness directional yarn 3 is oriented not on all of the area of the laminated fiber froup 2 but in parts not requiring any change on forming a fiber-reinforced composite material having a three dimensional shape by using the fibrous structural material 1 as the reinforcing material. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fiber structure and a composite material.
[0002]
[Prior art]
Fiber reinforced composites are widely used as lightweight structural materials. Fiber reinforced composite materials include those that use only short fibers or long fibers that are not continuous fibers as reinforcements, those that use woven or nonwoven fabrics as reinforcements, and those that use three-dimensional fabrics (three-dimensional fiber structures) as reinforcements. Some are used as
[0003]
When short fibers or long fibers are simply used as the reinforcing material, a three-dimensional fiber reinforced composite material can be obtained by hot pressing a plate-like material in which the reinforcing material is present in the matrix resin. However, fiber-reinforced composites using short fibers or long fibers as reinforcing materials are insufficient in strength, and handling of fibers is inconvenient when molding plate-like materials in which fibers are impregnated with resin. is there.
[0004]
When a two-dimensional fiber structure is used as a reinforcing material, such as a nonwoven fabric using chopped fibers or a woven fabric using a split yarn, the strength is simply higher than that of a fiber-reinforced composite material using short fibers or long fibers as a reinforcing material. And the handling of the material is better. However, in the case of using a torn yarn, the mechanical properties are reduced and the cutting step is a factor of cost increase. In addition, when the final product has a large thickness, these fiber-reinforced composite materials are used as a reinforcing material by laminating a plurality of nonwoven fabrics or woven fabrics, so that the strength in the thickness direction is low and the bending strength is also low.
[0005]
Japanese Patent Application Laid-Open No. 8-337666 discloses a deep-drawn preform including a bidirectional woven fabric having a warp and a weft as reinforcing fibers. In this preform, a thermoplastic polymer is linearly and continuously or discontinuously attached to at least one of the warp yarn and the weft yarn, and the minimum crossing angle of the yarn extending in two directions of the reinforcing fabric is 20 to The angle is 40 degrees. However, in the case of using a woven fabric as a reinforcing material, there is a restriction even if the mesh is coarsened, so there is a limit to deformation, and yarns (fibers) having different arrangement directions interfere with each other, so that the fibers are arranged straight. However, it is difficult to increase the strength of the fiber-reinforced composite material.
[0006]
[Problems to be solved by the invention]
Fiber reinforced composites using a three-dimensional fiber structure using continuous fibers as reinforcements are superior in strength to fiber reinforced composites using two-dimensional fiber structures as reinforcements. The body is more difficult to deform than a two-dimensional fiber structure. Therefore, a fiber-reinforced composite material using a three-dimensional fiber structure using continuous fibers as a reinforcing material must be adjusted to the product shape in advance so that the three-dimensional fiber structure does not have to be deformed when impregnated with resin or thereafter. It had to be manufactured in a different shape. However, in this case, a manufacturing apparatus and a jig for the fibrous structure are required according to the product shape, so that the manufacturing cost is increased.
[0007]
The present invention has been made in view of the above-mentioned conventional problems, and a first object of the present invention is to provide a fibrous structure capable of producing a high-strength fiber-reinforced composite material using continuous fibers at low cost. Is to provide. Another object of the present invention is to provide a composite material (prepreg) that enables a high-strength three-dimensional fiber-reinforced composite material using continuous fibers to be manufactured at low cost by press working.
[0008]
[Means for Solving the Problems]
In order to achieve the first object, the invention according to claim 1 is directed to a laminated fiber group in which fiber bundles composed of continuous fibers are arranged at least biaxially, and in a thickness direction for connecting the laminated fiber group. A fibrous structure formed in a plate shape with the arranged thickness direction yarns, wherein the thickness direction yarns are deformed when forming a three-dimensionally shaped fiber reinforced composite material from the fiber structure. Are arranged in unnecessary parts.
[0009]
Here, the term "yarn" does not only mean a twisted yarn, but also includes a fiber bundle (so-called roving) in which a large number of fibers are bundled and twisting is not substantially applied. Further, the “three-dimensional shape” means a shape in which a plane is bent, not a plane.
[0010]
When the fiber structure of the present invention is put into a mold and press-formed, a portion where the thickness direction yarn is not inserted is deformed and formed into a desired shape. Therefore, a high-strength fiber-reinforced composite material using continuous fibers can be manufactured at low cost. The resin serving as the matrix of the fiber-reinforced composite material may be impregnated after the fiber structure is put in a mold and molded, or may be impregnated with the resin before press-molding the fiber structure.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the thickness direction yarns arranged in the portion where the deformation is unnecessary are at least one of a length direction and a width direction of the fiber structure. It is arranged on either side of either one. In the present invention, since the thickness direction yarns are arranged on at least one of both sides in the length direction and the width direction of the fiber structure and the laminated fiber group is connected, handling of the fiber structure is improved. .
[0012]
According to a third aspect of the present invention, in the first or second aspect of the invention, the thickness direction yarns are arranged not only in the portion where the deformation is unnecessary but also in the portion where the deformation is required. The thickness direction yarns arranged in the unnecessary portions are formed of non-thermoplastic fibers, and the thickness direction yarns arranged in the portions requiring the deformation are formed of thermoplastic fibers.
[0013]
In the present invention, since the thickness direction yarns are arranged on the entire surface of the fiber structure, the function of retaining the shape of the fiber structure is enhanced, and handling becomes easier. Further, since the thickness direction yarns arranged in the portions that need to be deformed when forming a three-dimensionally shaped fiber reinforced composite material are thermoplastic fibers, the thickness direction yarns are softened or melted during heat molding. . As a result, the bonding function of the thickness direction yarn is reduced or eliminated, and the fibrous structure is easily deformed into a predetermined shape.
[0014]
According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the thickness direction yarns are arranged not only in the portion where the deformation is unnecessary but also in the portion where the deformation is necessary. The thickness direction yarn is formed of a thermoplastic fiber. In the present invention, since the thickness direction yarns are arranged on the entire surface of the fiber structure, the handling becomes easier as in the third aspect of the present invention. Further, since all the thickness direction yarns are formed of thermoplastic fibers, the fibrous structure is more easily deformed at the time of heat molding, and it is possible to cope with a complicated shape.
[0015]
Further, in order to achieve the second object, the composite material of the invention according to claim 5 is obtained by impregnating the fibrous structure according to any one of claims 1 to 4 with a thermoplastic resin. . Therefore, when the composite material of the present invention is used, a high-strength fiber-reinforced composite material using continuous fibers can be produced at low cost by pressing a flat composite material in a heated state.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1A, the fiber structure 1 has a laminated fiber group 2 in which fiber bundles made of continuous fibers are arranged biaxially, and a thickness of the laminated fiber group 2 for joining the laminated fiber group 2. And a thickness direction yarn 3 arranged in the direction. As shown in FIG. 1B, the x yarn 4a as a fiber bundle made of continuous fibers is arranged in one direction (in a plane orthogonal to the thickness direction of the fiber structure 1 (vertical direction in FIG. 1B)). 1 (b), the x yarn layers 4 are formed. The y yarns 5a as a fiber bundle made of continuous fibers are arranged in one direction in a plane orthogonal to the thickness direction of the fiber structure 1 in a state orthogonal to the x yarns 4a to form the y yarn layer 5. . The x-yarn layer 4 and the y-yarn layer 5 are alternately laminated in a plurality of layers to form a biaxially oriented laminated fiber group 2. The two axes are orthogonal to each other.
[0017]
The thickness direction yarn 3 is not on the entire surface of the laminated fiber group 2 but on a portion that does not need to be deformed when forming a three-dimensionally shaped fiber reinforced composite material 6 (shown in FIG. 3) using the fiber structure 1 as a reinforcing material. Are arranged. In this embodiment, the thickness direction yarns 3 are arranged on both sides of the fiber structure 1. The thickness direction yarn 3 is folded in a U-shape on one surface (the lower surface in FIG. 1B) of the laminated fiber group 2, and the thickness direction yarn 3 on the other surface (the upper surface in FIG. 1B). Are continuously inserted in the laminated fiber group 2 again at the insertion position separated by the arrangement pitch of. The retaining yarn 7 is inserted into a portion where the thickness direction yarn 3 is folded back into a U-shape. The x yarn layer 4 and the y yarn layer 5 are joined by tightening the thickness direction yarn 3 and the retaining yarn 7.
[0018]
Continuous fibers are used as the thickness direction yarn 3, the x yarn 4a, the y yarn 5a, and the retaining yarn 7. In this embodiment, carbon fibers are used as continuous fibers. The carbon fiber has about 3000 to 24000 filaments. The arrangement pitch of the thickness direction yarns 3 is about 3 to 5 mm. The thickness of the fibrous structure 1 is about 5 mm.
[0019]
Next, a method for manufacturing the fibrous structure 1 will be described.
As shown in FIGS. 2A and 2B, first, the laminated fiber group 2 is formed using a rectangular frame 8 in which a large number of pins 8a are detachably provided at a predetermined pitch. The pitch of the pins 8a matches the pitch of the x yarn 4a and the y yarn 5a.
[0020]
As shown in FIG. 2A, the x yarn 4a is folded in a state of being engaged with the pin 8a to form the x yarn layer 4 oriented in one direction. As shown in FIG. 2B, the y thread 5a is similarly folded back in a state of engaging with the pin 8a, and is oriented in one direction orthogonal to the x thread 4a to form the y thread layer 5. This is repeated a predetermined number of times to form the laminated fiber group 2. 2 (a) and 2 (b), the arrangement intervals of the x yarns 4a and the y yarns 5a are broadly illustrated. However, in practice, the x yarns 4a or the y yarns 5a arranged adjacent to each other are in contact with each other. Are arranged. Therefore, as shown in FIG. 1 (b), in a portion where the thickness direction yarns 3 are not arranged, adjacent x yarns 4a and y yarns 5a are in contact with each other.
[0021]
Next, the thickness direction yarn 3 is inserted into the laminated fiber group 2 by a method disclosed in, for example, JP-A-8-218249. More specifically, in the thickness direction of the laminated fiber group 2, an insertion needle (not shown) having a hole at the tip and hooking the thickness direction thread 3 into the hole is inserted. The insertion needle is advanced and inserted until the hole of the insertion needle on which the thickness direction thread 3 is hooked penetrates the laminated fiber group 2. Thereafter, the insertion needle is retracted slightly. As a result, the thickness direction thread 3 is in a state of forming a U-shaped loop.
[0022]
Next, when a retaining thread needle (not shown) passes through the U-shaped loop and reaches the end of the laminated fiber group 2, it stops. At this time, the retaining thread 7 is hooked on the tip of the retaining thread needle. Then, the retaining thread needle is pulled back, and the retaining thread 7 is inserted into the U-shaped loop of the thickness direction thread 3. In this state, the insertion needle is pulled back, the retaining thread 7 is tightened by the thickness direction thread 3, and the respective thread layers are joined. This thickness direction thread 3 is inserted into a predetermined region of the laminated fiber group 2, that is, a portion that does not need to be deformed when forming the three-dimensional fiber reinforced composite material 6 using the fiber structure 1 as a reinforcing material. The fiber structure 1 in which the respective yarn layers 4 and 5 of the laminated fiber group 2 are joined by the thickness direction yarn 3 is manufactured.
[0023]
This fiber structure 1 is used for manufacturing a fiber-reinforced composite material using a three-dimensional fiber structure as a reinforcing material. When a thermoplastic resin is used as the matrix resin of the composite material, the fibrous structure 1 is impregnated with the thermoplastic resin by a general impregnation method such as a melt impregnation molding method, cooled, and cooled to form a composite as a plate-like material for molding. A material (prepreg) is formed. Next, after the material is heated and softened before forming, it is press-formed by a press-forming machine and cooled to obtain a fiber-reinforced composite material 6 in a product shape as shown in FIG. When a plate-like material impregnated with resin is put into a mold and press-molded in the fibrous structure 1, a portion where the thickness direction thread 3 is not inserted is easily deformed and formed into a desired shape. Therefore, a high-strength fiber-reinforced composite material using continuous fibers can be manufactured at low cost. As the thermoplastic resin, for example, nylon, polybutylene terephthalate, polycarbonate and the like are used.
[0024]
This embodiment has the following effects.
(1) The fiber structure 1 includes a laminated fiber group 2 in which fiber bundles composed of continuous fibers are arranged biaxially, and a thickness direction yarn 3 arranged in the thickness direction to join the laminated fiber group 2. The thickness direction yarn 3 is arranged in a portion that does not need to be deformed when forming the three-dimensional fiber reinforced composite material 6 from the fiber structure 1. Therefore, when the fibrous structure 1 is put into a mold and press-formed, a portion where the thickness direction thread 3 is not inserted is easily deformed and formed into a desired shape. As a result, a high-strength fiber-reinforced composite material using continuous fibers can be manufactured at low cost.
[0025]
(2) The thickness direction yarns 3 are arranged on both sides of the fiber structure 1, and the laminated fiber group 2 is bonded on both sides by the thickness direction yarns 3, so that the fiber structure 1 is not impregnated with the resin. Also, the handleability of the fiber structure 1 is improved.
[0026]
(3) Since the handling property of the fibrous structure 1 is good, transportation of the fibrous structure 1 is simplified, and a person who manufactures the fibrous structure 1 and a fiber-reinforced composite material 6 that uses the fibrous structure 1 as a reinforcing material. Even if the manufacturer is different, there is no trouble in the operation.
[0027]
(4) Since the thickness direction yarn 3 is not inserted in the portion where the deformation is necessary, the strength of the region is lower than that of the portion where the thickness direction yarn 3 is arranged. However, since continuous fibers are arranged and the thickness direction yarns 3 are arranged in other regions, the strength as a fiber-reinforced composite material having a three-dimensional fiber structure of the continuous fibers as a reinforcing material in a product shape is obtained. Is kept.
[0028]
(5) Since the fiber-reinforced composite material 6 is manufactured by using a material (composite material) in which the fibrous structure 1 is impregnated with a thermoplastic resin in advance, the handling and storage properties are performed in the state of the fibrous structure 1. Improved compared to the case. In addition, a manufacturer of the fiber-reinforced composite material 6 can easily manufacture the fiber-reinforced composite material 6 by using an existing press machine by purchasing the material.
[0029]
The embodiment is not limited to the above, and may be configured as follows, for example.
○ Instead of a method of manufacturing a fiber-reinforced composite material 6 by press-molding a material in which the fibrous structure 1 is previously impregnated with a thermoplastic resin serving as a matrix, the fibrous structure 1 is put into a mold and then molded. The impregnation method may be used. In this method, not only a thermoplastic resin but also a thermosetting resin can be used as the matrix resin. When a thermosetting resin is used as the matrix resin, a fiber-reinforced composite material 6 having higher strength than when a thermoplastic resin is used can be manufactured. As the thermosetting resin, epoxy resin, unsaturated polyester resin, phenol resin, polyimide resin, vinyl ester resin and the like are used.
[0030]
○ As shown in FIG. 4, the thickness direction yarn 3 is not only deformed when forming the three-dimensionally shaped fiber reinforced composite material 6 from the fiber structure 1, but also when deformation is unnecessary. In addition, they are arranged in the portions that need to be deformed. The arrangement density of the thickness direction yarns 3 may be the same as that of the portion that does not need to be deformed, but as shown in FIG. Then, the thickness direction yarns 3 arranged at the portions where the deformation is not required may be formed of non-thermoplastic fibers, and the thickness direction yarns arranged at the portions where the deformation is required may be formed of the thermoplastic fibers. In this case, since the thickness direction yarns 3 are arranged on the entire surface of the fibrous structure 1, the function of retaining the shape of the fibrous structure 1 is enhanced, and the handling property is further improved. Further, since the thickness direction yarns 3 arranged in the portions that need to be deformed when forming the three-dimensionally shaped fiber reinforced composite material 6 are thermoplastic fibers, the thickness direction yarns 3 are softened during heat molding. Alternatively, it melts. As a result, the bonding function of the thickness direction yarn is reduced or eliminated, and the fibrous structure 1 is easily deformed into a predetermined shape. In addition, since the thickness direction yarns 3 arranged in the portions where the deformation is not required are non-thermoplastic fibers, they do not soften or melt when the fiber structure 1 is heat-formed, and the physical properties of the fiber-reinforced composite material 6 are This is equivalent to the arrangement of the thickness direction yarns 3 of non-thermoplastic fibers only in the portions where the deformation is not required.
[0031]
○ In the fibrous structure 1 in which the thickness direction yarns 3 are arranged not only in the portion where the deformation is not required but also in the portion where the deformation is required, all the thickness direction yarns 3 are assumed to be formed of thermoplastic fibers. . Also in this case, since the thickness direction yarns 3 are arranged on the entire surface of the fibrous structure 1, handling properties are further improved as in the above-described configuration. Further, since the thickness direction yarns 3 are all formed of thermoplastic fibers, the fibrous structure 1 is more easily deformed at the time of heat molding, and it is possible to cope with a complicated shape.
[0032]
When a thermoplastic fiber is used as the thickness direction yarn 3, the thermoplastic fiber used is made of the same thermoplastic resin as the matrix resin used when manufacturing the fiber-reinforced composite material 6. In this case, since no foreign resin is present in the matrix resin of the fiber-reinforced composite material 6, the physical properties of the fiber-reinforced composite material 6 are improved as compared with the case where the thermoplastic fibers are formed of the matrix resin and another thermoplastic resin. I do.
[0033]
The thickness direction yarns 3 may be arranged on at least one of both sides in the length direction and the width direction of the fiber structure 1. For example, as shown in FIG. 5, the thickness direction yarns 3 may be arranged at both ends of a portion requiring deformation in addition to both side portions requiring no deformation. By arranging the thickness direction yarns 3 in this manner, the shape stability of the fiber structure 1 is improved. In addition, even in a portion that needs to be deformed, the thickness direction yarns 3 arranged only at both ends thereof hardly hinder the deformation of the fibrous structure 1.
[0034]
○ The continuous fibers need not be carbon fibers. For example, glass fiber, polyaramid fiber, ceramic fiber and the like may be used.
The same fiber may not be used as the x yarn 4a and the y yarn 5a, but different fibers may be used. For example, one fiber may be lower in strength than the other fiber in accordance with the physical properties required of the fiber-reinforced composite material 6. In this case, the production cost can be reduced without making the fiber reinforced composite material 6 excessive quality.
[0035]
The thickness direction yarns 3 do not necessarily need to be arranged at the same pitch as the arrangement pitch of the x yarns 4a and the y yarns 5a, and may be arranged at an arbitrary pitch corresponding to the physical properties required of the fiber reinforced composite material 6. Good. When the arrangement of the thickness direction yarns 3 is made dense, the bonding force to the laminated fiber group 2 is strong, and when the arrangement of the thickness direction yarns 3 is made sparse, the bonding force becomes weak, so that the bonding force can be adjusted.
[0036]
The laminated fiber group 2 only needs to be at least biaxially oriented, and has two types of yarn layers, an x yarn layer 4 composed of x yarns 4a and a y yarn layer 5 composed of y yarns 5a arranged to be orthogonal to each other. It does not need to be formed with For example, the laminated fiber group 2 may be formed of yarn layers in which the arranged yarns are not arranged at right angles to each other.
[0037]
○ The laminated fiber group 2 may have three or more axes. For example, a bias yarn layer may be inserted according to the strength required for the product.
○ The fibrous structure 1 does not have to be a flat plate. It may be a curved surface having a small curvature.
[0038]
O Without using the retaining thread 7, the thread layers may be joined by general sewing using only the thickness direction thread 3.
The thickness direction yarns 3 need not be arranged continuously from one end to the other end of the fibrous structure 1. Even if it is discontinuous, it is only necessary to penetrate and connect each yarn layer.
[0039]
In the case of manufacturing the fiber reinforced composite material 6, it is not limited to forming one fiber reinforced composite material 6 (product) with one fiber structure 1. A plurality of fibrous structures 1 may be arranged or stacked depending on the product shape or required performance.
[0040]
The matrix of the fiber-reinforced composite material 6 may be other than resin, for example, metal. In this case, as the fibers constituting the fibrous structure 1, carbon fibers, ceramic fibers, and the like that are not damaged by the melting temperature of the matrix metal are used.
[0041]
The technical ideas (inventions) that can be grasped from the above embodiment will be described below.
(1) A fiber-reinforced composite material using the fiber structure according to claim 3 or 4 as a reinforcing material, and using the same thermoplastic resin as the material of the thickness direction yarn as a matrix resin.
[0042]
(2) A fiber-reinforced composite material comprising the fiber structure according to any one of claims 1 to 4 as a reinforcing material.
(3) In the fiber reinforced composite material described in the technical concept (2), a resin is used as a matrix.
[0043]
【The invention's effect】
As described above in detail, according to the first to fourth aspects of the present invention, it is possible to manufacture a high-strength fiber-reinforced composite material using continuous fibers at low cost. According to the invention described in claim 5, it is possible to manufacture a three-dimensional fiber reinforced composite material having high strength using continuous fibers at a low cost by press working.
[Brief description of the drawings]
FIG. 1A is a schematic perspective view of a fiber structure, and FIG. 1B is a schematic partial cross-sectional view of the fiber structure.
2A is a schematic diagram showing an arrangement state of an x yarn layer, and FIG. 2B is a schematic diagram showing an arrangement state of a y yarn layer.
FIG. 3 is a schematic perspective view of a fiber-reinforced composite material.
FIG. 4 is a schematic perspective view of a fiber structure according to another embodiment.
FIG. 5 is a schematic perspective view of a fiber structure according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fiber structure, 2 ... Laminated fiber group, 3 ... Thickness direction thread, 4a ... X thread as a fiber bundle composed of continuous fibers, 5a ... Y thread similarly, 6 ... Fiber reinforced composite material.

Claims (5)

A fibrous structure comprising a laminated fiber group in which fiber bundles composed of continuous fibers are arranged at least biaxially, and a thickness direction yarn arranged in the thickness direction for coupling the laminated fiber group The fiber structure, wherein the thickness direction yarns are arranged in a portion that does not need to be deformed when forming a three-dimensionally shaped fiber-reinforced composite material from the fiber structure. 2. The fiber structure according to claim 1, wherein the thickness direction yarns arranged in the portions where the deformation is unnecessary are arranged on at least one of both sides in a length direction and a width direction of the fiber structure. body. The thickness direction yarn is arranged in a portion requiring deformation in addition to the portion in which the deformation is not required, and the thickness direction yarn arranged in the portion in which the deformation is not required is formed of a non-thermoplastic fiber, 3. The fibrous structure according to claim 1, wherein all of the thickness direction yarns arranged in portions requiring deformation are formed of thermoplastic fibers. 3. The thickness direction yarn according to claim 1, wherein the thickness direction yarn is arranged in a portion requiring deformation in addition to the portion not requiring deformation, and all the thickness direction yarns are formed of thermoplastic fibers. Fiber structure. A composite material comprising the fibrous structure according to any one of claims 1 to 4 impregnated with a thermoplastic resin.

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