JP2002264235A - Reinforcing multishaft stitch cloth and fiber reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multishaft stitch cloth excellent in mechanical strength and capable of inexpensively obtaining FRP, and fiber reinforced plastic using the stitch cloth. SOLUTION: The reinforcing multishaft stitch cloth is characterized in that a large number of fiber yarns are parallelly arranged in a sheetlike manner to form layered constitution and at least two layers are laminated so as to cross each other and a use mode of the fibers is different between at least two layers and a plurality of the layers are integrated by stitch yarns. The fiber reinforced plastic using the reinforcing multishaft stitch cloth is also disclosed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiaxial stitch fabric used as a reinforcing fiber base of fiber reinforced plastic (FRP), and a fiber reinforced plastic (FRP) using the fabric.

[0002]

2. Description of the Related Art Fiber reinforced plastics composed of continuous reinforcing fibers have excellent mechanical properties in the fiber axis direction, but as the distance from the fiber axis direction increases, the mechanical properties decrease sharply and the directionality (anisotropic) decreases. Have

[0003] As a countermeasure to suppress this characteristic, for example, the fiber axis direction is the length (0 °) direction and the width (90 °) of the FRP molded body so that the mechanical characteristics become pseudo-isotropic.
2. Description of the Related Art Fiber reinforced plastics are formed by laminating fiber layers such as woven fabrics in a direction or an oblique (± α ±) direction.

However, even in this case, if a normal woven fabric is used, the fiber arrangement direction is the length (0 °) direction and the width (90 °) direction of the woven fabric. Can not be done. Therefore, as a further measure,
The woven fabric is cut diagonally, and the cut end of the woven fabric is
Laminated so as to be parallel to the fabrics arranged in the ゜ direction and the 90 ° direction, and the arrangement direction of the fibers cut in the oblique direction is ± 45.
Molding is performed in such a way as to become ゜.

[0005] However, in such a method, especially when a large-sized structure is formed, it takes time and effort to cut and laminate the woven fabric, and the loss of material is large. In addition, (0
(/ 90 °) and (+ 45 ° / −45 °) arranged fabrics are liable to be misaligned, and it is difficult to accurately perform fiber orientation.

[0006] In order to solve the above-mentioned problem, recently, a weft insertion tricot device has been used in the direction of + α ゜, -α ゜ or 0 ° and / or 90 ° with respect to the length direction of the fabric, ie, in two or more directions. A so-called multiaxial stitch fabric, in which reinforcing fibers are arranged in parallel in layers and stitched together with a stitch such as a polyester fiber yarn in a state where these are laminated, has attracted attention. This fabric has + α ゜, -α ゜, 0 ゜ and 90
The arrangement fibers of ゜ are united by stitch yarns, so that the cutting work does not require any preparation work to arrange them in a predetermined direction, and the quasi-isotropic properties can be obtained with one piece of cloth. In addition, there is an advantage that the laminating operation is largely labor-saving and that a large-sized structure can be formed at low cost.

[0007] Recently, the commercialization of thick carbon fiber yarns has been started, and the production cost of carbon fibers has been reduced and the cost has been reduced.

However, although carbon fibers have become inexpensive, large structures such as roofs, bridges, trucks and boats use a large amount of reinforcing fibers. It is rare to be done, arrange the carbon fiber base material in the direction where strength and rigidity are required,
In other directions, cost reduction is being attempted by using inexpensive glass fiber together, but the cost is still high and further cost reduction is required.

[0009] Further, the base material such as woven fabric used for fiber reinforced plastic usually has different manufacturers from different fiber types. Therefore, it is necessary to arrange materials to a plurality of manufacturers, and inventory management is complicated. Become. Further, since the steps of manufacturing the carbon fiber base material and the glass fiber base material are different from each other, there is a problem that the processing cost of the base material is also high from this point.

[0010]

SUMMARY OF THE INVENTION In view of the background of the prior art, the present invention provides an inexpensive F
An object of the present invention is to provide a multiaxial stitched fabric from which RP can be obtained and a fiber-reinforced plastic reinforced by the fabric.

[0011]

The present invention employs the following means in order to solve the above-mentioned problems.

That is, the multiaxial stitched fabric of the present invention comprises:
It consists of the following (1), and more preferably (2) to
It has the configuration of (6). (1) A number of fiber yarns are arranged in a sheet shape in parallel to form a layer structure, and the layers are used in a cross-laminated state of at least two or more layers. Wherein the plurality of layers are integrated with stitch yarns. (2) The reinforcing multiaxial stitched fabric according to the above (1), wherein the fiber yarn is a fiber yarn having a tensile modulus of 70 GPa or more. (3) The reinforcing multiaxial stitched fabric according to the above (2), wherein a carbon fiber thread or a glass fiber thread or both are used as the fiber thread. (4) The reinforcing multiaxial stitched fabric according to (3), wherein the carbon fiber yarns are arranged at least in the length direction of the fabric. (5) The crossing angle at which at least two or more layers of the fiber yarns are cross-laminated with respect to the length direction of the fabric,
The reinforcing multiaxial stitch fabric according to the above (1), (2), (3) or (4), which intersects at least in two directions of + α ゜ and −α ゜. (6) The reinforcing multiaxial stitched fabric according to the above (5), wherein the intersection angle α ゜ is 45 °.

Further, the fiber reinforced plastic according to the present invention has the following configuration (7), and more preferably has the configuration (8). You. (7) A fiber-reinforced plastic using the reinforcing multiaxial stitch fabric of (1), (2), (3), (4) or (5) as a reinforcing fiber. (8) The fiber-reinforced plastic according to the above (7), wherein a reinforcing multiaxial stitch fabric in which at least four or more fiber yarn layers are cross-laminated is used as a reinforcing fiber.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multiaxial stitch fabric for reinforcement and a fiber reinforced plastic of the present invention will be described below with reference to the drawings.

The multiaxial stitching fabric for reinforcement of the present invention has a layer structure in which a large number of fiber yarns are arranged in parallel in a sheet form, and the layers are used by cross-laminating at least two or more layers. At least two layers differ in the mode of use of the fibers constituting the layer, and the plurality of layers are integrated with a stitch yarn.

In the present invention, the term "cross lamination" means that a plurality of layers of a sheet-like material formed by arranging a large number of fiber yarns in parallel are arranged so that the fiber arrangement direction of each layer intersects.
Lamination means that the fiber directions are shifted from each other.

[0017] The expression "the use mode of the fiber constituting the layer is different between at least two layers" means that the fiber yarn layer used and laminated is used between at least two layers. Specifically, when comparing at least two layers, for example, the types of constituent fibers are different, or the physical properties such as thickness and strength and the number of Are different, or even if the same physical properties such as fiber type, thickness, strength, etc. are used, the number used per unit area or the number used per unit volume is different, or the same carbon Even if the same number of fiber yarns and glass fiber yarns are used per unit area, one uses a relatively large amount of carbon fiber yarns and the other uses a relatively large number of glass fiber yarns. Such as fiber Use mode is one that means that are different from each other.

FIG. 1 is a schematic perspective view illustrating a multiaxial stitch fabric according to the present invention.

From the lower surface of the fabric 1, a large number of glass fiber yarns 2 are arranged in parallel in a direction oblique to the length direction A to form a + α ゜ (45 °) layer 6; A large number of carbon fiber yarns 3 are arranged in parallel in the width direction to form a layer 7 of 90 °, and then a large number of glass fiber yarns 4 are arranged in parallel in the diagonal direction at −α ゜ (45 °). ), And then a large number of carbon fiber yarns 5 in the longitudinal direction of the fabric.
Are arranged in parallel to form a 0 ° layer 9, and in a state where four layers having different arrangement directions are stacked, these four layers are stitched and integrated with a stitch thread 10.

In the present invention, the stitches formed by the stitch thread when the stitches are integrated may be a single-ring stitch or a 1/1 tricot knit stitch.

In the fabric (stitch fabric) shown in FIG.
The stitched fabric according to the present invention has a structure in which the carbon fiber yarns 5 are arranged in the length direction and the width direction of one cloth and the glass fiber yarns 4 are arranged in the bias direction.

By the way, according to the conventional method, a fabric in which carbon fibers are arranged in a length direction (0 °) and a width direction (90 °) and a fabric in which glass fibers are arranged in a length direction and a width direction are 45 °. Cut into a parallelogram shape in the bias direction, and then cut into a rectangular shape.The woven piece is placed on the carbon fiber fabric so that the long side of this rectangular shape is the length direction of the carbon fiber woven fabric. It was necessary to laminate so as to overlap. On the other hand, according to the multi-axis stitched fabric of the present invention, cutting and laminating work of the woven fabric pieces are not required, so that significant labor saving can be achieved. Further, as described above, when the parallelogram is cut into a rectangular shape, the glass fiber fabric portion other than the rectangular shape is lost. According to the present invention, the loss can be eliminated.

Therefore, the multiaxial stitched fabric according to the present invention can be obtained by using, for example, one kind of weft insertion tricot device, and the process management is easy and the processing cost can be reduced. And material loss is reduced.

Further, the multiaxial stitched fabric of the present invention has a woven yarn bending (crimp) caused by interlacing of yarns like a woven fabric.
Since the multifilament reinforcing fiber yarns are substantially arranged straight and stitched and integrated with stitching yarn, even if stress acts in the state of FRP, the reinforcing fiber or resin Because there is virtually no stress concentration on
This makes it possible to exhibit the properties of the reinforcing fiber without regret, and to obtain an FRP having high strength and high rigidity.

The fibers for plastic reinforcement which can be used in the present invention include, for example, polyester fibers, nylon fibers, polypropylene fibers, polyethylene fibers, vinylon fibers, polyaramid fibers, glass fibers, and carbon fibers. It is not something to be done.

In particular, large structures such as those made of FRP generally require a rigidity due to a long span, and therefore the tensile elastic modulus in the length direction (0 °) of the multiaxial stitched fabric. It is preferable to arrange carbon fibers having a high elastic modulus of 200 GPa or more. 200 GPa
If it is less than the required rigidity, it may be necessary to increase the thickness of the structure in order to obtain the required rigidity. In some cases, the amount increases, which increases the cost and is not preferable.

As described above, by using reinforcing fibers of different fiber types in the required layers, a multiaxial stitched fabric that is preferable as a reinforcing substrate for FRP can be obtained.

Since the carbon fiber has good adhesiveness to the matrix resin and has a large tensile modulus of 200 GPa or more, a large improvement in rigidity can be obtained even with a small amount of fiber, so that the weight of the FRP molded article can be reduced. This is preferred.

In forming the fabric, the needle penetrates the fiber layer, so that the carbon fiber thread used is JIS L 1 in order to prevent the fiber from being damaged by the needle.
The hooking strength measured according to the method No. 013 is 0.
It is preferably 900 N or more per 9 mm ² . If the value is 900 N or less, not only the tensile strength and the tensile modulus are reduced due to fiber damage, but also a large amount of carbon fiber dust is generated, which is not preferable in terms of hygiene.

The glass fiber has a tensile modulus of 70 G
Since it is as high as about Pa, has good resin impregnating properties and adhesion to resin, and is inexpensive, it is preferable to use it alone or as a combination of carbon fiber and glass fiber.

Further, for example, organic fibers such as polyester fiber, nylon fiber, polypropylene fiber, polyethylene fiber, vinylon fiber and polyaramid fiber are arranged in the outermost layer of the stitch cloth, and the other layers are made of glass fiber or carbon fiber. A fiber layer, and the organic fiber layer
When formed so as to be the outermost layer of P, a new function can be imparted to the FRP, such as improvement of the wear resistance, cut resistance and impact resistance of the FRP.

In the present invention, the preferable range of the thickness of the fiber used for reinforcing the plastic is generally difficult, but preferably about 300 to 5,000 tex. In particular, when a thick reinforcing fiber yarn is used, the reinforcing fiber is inexpensive, so that an inexpensive fabric can be obtained, which is preferable. However, if the basis weight of the reinforcing fibers per layer (the amount of fibers used per area) is small, there is a gap between the yarns in the layer, and when integrated with stitch yarn, the fiber density is partially uneven. When molding such a material, it is necessary to pay attention that the FRP becomes thicker at a place where the fiber density is large, and the FRP becomes thinner at a place where the fiber density is small, so that the FRP may have an uneven surface. is there.

In particular, when a thick reinforcing fiber yarn such as 700 to 5,000 tex is used, the reinforcing fiber yarn is oscillated by a roller or air jet before the stitch yarn is integrated. Spreading flat and thin so that the yarn bundle is at least twice the width of the yarn wound on the bobbin and the thickness of the yarn bundle is 0.3 mm or less, the density of the reinforcing fibers over the entire surface of the fabric Are present uniformly, and it becomes possible to obtain FRP having a smoother surface, which is preferable.

Even if the reinforcing fibers are of the same fiber type, the outermost layer of the fabric located on the outermost layer of the FRP has the same basis weight as the other layers, and a relatively thin yarn of 300 to 900 tex. Are arranged, the surface becomes a smooth FRP.

The stitch yarn used in the present invention is preferably selected from nylon fibers, polyester fibers, glass fibers, carbon fibers, copolymerized nylon fibers, modified polyester fibers and the like.

If the thickness of the stitch thread is too small, the thread may break during the stitch operation. If the thickness is too large, the stitch thread portion will be in a convex state. In particular, it is preferable that the density be in the range of 50 to 400 decitex, since irregularities may appear on the surface and the smoothness may be lost. More preferably, it is 70 to 300 dtex.

In the fabric shown in FIG. 1, a four-layer structure of + α ゜ layer / 90 ゜ layer / −α ゜ layer / 0 ゜ layer has been described as the lamination structure of the reinforcing fiber layer. The effect of the present invention is not limited to the above. At least the effect of the present invention is that the layer structure is formed in the direction of the bias (± α ゜) between the −α ゜ layer and the + α ゜ layer with respect to the length direction of the fabric. Is preferred. According to various findings of the present inventors, the number of layers to be laminated is preferably 3 or more, more preferably 4 or more, and 4 to 10 layers is the most preferable configuration.

Further, the order of the layer constitution is -α ゜ / 90 ゜ / +
It is not limited to the order of α ゜ / 0 ゜.
α / 90 ° / + α ゜ or 0 ° / −α ゜ / + α ゜ / 90 ° can be appropriately designed. Also, the -α ゜ layer and + α
に If the fabric has reinforcing fibers arranged only in the bias direction of the layer, when the fiber is pulled in the length direction of the fabric, the direction of the reinforcing fibers is easily shifted and the width direction of the fabric becomes unstable, and the form is unstable. . In such a case, for example, auxiliary yarns such as glass fiber, carbon fiber and polyaramid fiber are arranged in the direction of 0 ° or 90 ° in an amount of about ²⁰ to 100 g / m ² , and the −α layer, the + α layer and the stitch yarn are arranged. When integrated with, the form can be stabilized.

The bias angle α ゜ is most preferably 45 ° from the viewpoint of laminating multiaxial stitch fabrics in the longitudinal direction of the FRP molded article and effectively performing shear reinforcement by reinforcing fibers.

In the embodiment shown in FIG. 1, glass fibers are arranged in the + α ＋ layer and the −α ゜ layer,
Although the case where carbon fibers are arranged in the {layer and 90} layer has been described, the invention is not necessarily limited to this.
The type of fiber and the number of layers in which the fiber is arranged can be variously configured according to the desired effect.

The multi-axis stitched fabric according to the present invention comprises:
In particular, it is suitable as a molding substrate for a large-sized structure.At least, when carbon fiber yarns are arranged in the length direction of the fabric, carbon fibers having a large elastic modulus can be arranged in the length direction of the long molding, Effective rigidity reinforcement of a long molded body on which a bending moment acts can be achieved.

As described above, even when fibers of the same type are used, carbon fibers having different properties, for example, tensile strength, tensile modulus and thermal conductivity, can be arranged in different layers. Thus, the mode of use of the fibers between the two layers can be made different.

As described above, instead of using the same type of fiber yarn for each layer constituting the stitched fabric, the use of the fiber yarn for each layer may be varied according to the purpose, so that the FRP is formed. An effective reinforcing effect can be obtained, and a new function can be provided at the same time.

For example, when carbon fibers are arranged in the length direction of the fabric, a long large F such as a windmill blade for wind power generation can be used.
A particularly effective reinforcing effect is obtained against bending of the RP structure, and when carbon fibers are arranged in the ± 45 ° direction, a particularly effective reinforcing effect is obtained against shearing.

Further, since a single piece of cloth constitutes a base material in which fiber yarns are arranged in, for example, a layer of + α ゜, a layer of -α ゜, a layer of 0 ゜ or a layer of 90 ゜. Further, it is not always necessary to combine or cut different base materials, and it is possible to greatly reduce the cost as compared with the case where the same type is used.

[0046]

The multiaxial stitching fabric for reinforcement of the present invention has a layer structure in which a large number of fiber yarns are arranged in parallel in a sheet form, and the layers are used in a cross-laminated state of at least two or more layers. At least two layers differ in the mode of use of the fibers constituting the layers, and since the plurality of layers are integrated with stitch yarns, the fibers are oriented in a plurality of directions, and the FRP was formed. Sometimes an effective reinforcing effect is obtained, a new function can be provided, and a significant cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic model perspective view illustrating a multi-axis stitched fabric.

[Explanation of symbols]

 1: Multi-axial stitched fabric 2: Glass fiber yarn of + α layer 3: Carbon fiber yarn of 90 ° layer 4: Glass fiber yarn of −α layer 5: 0 Carbon fiber yarn of layer 6: Fabric 7: 90 ° carbon fiber layer forming a fabric 8: -α glass fiber layer 9 forming a fabric 9: Carbon fiber layer 10 forming a fabric 10: Stitch yarn A: The longitudinal direction of the fabric

Claims (8)

[Claims] 1. A multi-filament yarn is arranged in parallel in a sheet form to form a layer structure, and said layers are used by being cross-laminated at least two or more layers. A multiaxial stitching fabric for reinforcement, which is used in a different manner, and wherein the plurality of layers are integrated with a stitch yarn. 2. The multiaxial stitching fabric for reinforcement according to claim 1, wherein the fiber yarn is a fiber yarn having a tensile modulus of 70 GPa or more. 3. The multiaxial stitching fabric for reinforcement according to claim 2, wherein a carbon fiber yarn or a glass fiber yarn or both are used as said fiber yarns. 4. The multiaxial stitching fabric for reinforcement according to claim 3, wherein the carbon fiber yarns are arranged at least in the length direction of the fabric. 5. The crossing angle at which at least two or more fiber yarn layers are cross-laminated with each other at least in two directions of + α ゜ and -α ゜ with respect to the length direction of the fabric. The reinforcing multiaxial stitched fabric according to claim 1, 2, 3, or 4, wherein: 6. The multiaxial stitching fabric for reinforcement according to claim 5, wherein said crossing angle α ゜ is 45 °. 7. A fiber reinforced plastic comprising the reinforcing multiaxial stitch fabric according to claim 1, 2, 3, 4, 5 or 6 as a reinforcing fiber. 8. The fiber reinforced plastic according to claim 7, wherein a reinforcing multiaxial stitch fabric in which at least four or more fiber yarn layers are cross-laminated is used as a reinforcing fiber. .