JPH01229838A - Reinforced base material for composite material - Google Patents

Abstract

PURPOSE:To reduce filament breakage and raising in weaving by arranging plural carbon fiber bundles each consisting plural fibers and arranged mutually parallel in sheet form to layer form so as to mutually cross and forming into woven structure using a specific auxiliary yarn. CONSTITUTION:A yarn group 4 arranging plural and straight carbon fiber bundles 1 mutually parallel in sheet form and yarn group 3 arranging plural and straight carbon fiber bundles 3 mutually parallel in sheet form are arranged in layer form so that direction of the carbon fiber bundles 1 and 3 are mutually crossed at right angle and formed into woven structure using auxiliary yarns 5 and 6. The auxiliary yarns 5 and 6 have two single yarns of carbon fiber bundle being <=800 denier in fineness and 200-1200 in the number of filament, <=0.5 denier in fineness of filament and >=2.5% in breaking elongation of the filament. The auxiliary yarns 5 and 6 have upper twist and each single yarn have 0.1-0.8 times twist of upper twist number in the range of 20-180turn/m and twist of single yarn is reverse to upper twist thereof in twist direction.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention is applicable to carbon fiber reinforced plastics (cFRP), carbon fiber reinforced carbon (cFRC), carbon fiber reinforced metals (
It relates to a base material used as a so-called matrix reinforcing material when molding composite materials such as cFRM).

[Prior art] Reinforcement made of carbon fiber fabric when molding composite materials)
A base material is often used. However, in woven fabrics, the yarns are bent (crimped) at the intersection of the warp and weft, and stress is concentrated in that area, so the characteristics of carbon fiber, such as high strength and high elastic modulus, cannot be fully utilized. The problem is that it is not available.

On the other hand, Japanese Unexamined Patent Publication No. 55-30974 discloses several books,
A plurality of yarn groups consisting of practically straight carbon fiber bundles, which are aligned parallel to each other in a sea pattern, are layered so that the directions of the carbon fiber bundles intersect with each other between adjacent 11 spaces. A reinforcing substrate is described which is arranged and woven with auxiliary threads. This base material avoids the above-mentioned disadvantages because the carbon fiber bundles are straight for practical purposes and do not have bends that would cause stress concentration.

By the way, as auxiliary yarns used when manufacturing such reinforcing base materials, fiber yarns such as glass fiber yarns and bonoester fiber yarns can also be used, but these have poor water absorption. The composite material H may be large in size, have low heat resistance, have poor adhesion with the composite material, for example, matrix resin, or have a large thermal expansion difference with carbon fibers, resulting in deterioration of the properties of the composite material H due to thermal 1-noise fatigue. Due to problems such as poor mechanical properties such as strength and elastic modulus,
It is said that it is most preferable to use carbon fiber yarn, which is free from such concerns. However, if carbon fiber yarns are used in the form of fiber bundles, the carbon fibers are extremely brittle, and as a result, single fibers may break due to abrasion during weaving, or significant fluffing may occur, resulting in damage to the base material and even composite materials. It is difficult to improve the mechanical properties and reliability of materials.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above problems of conventional base materials, and because there is less worry about single fiber breakage and fuzzing during weaving, it is possible to The object of the present invention is to provide a reinforcing base material that can improve the mechanical properties of the material and also improve the reliability of the composite material.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a yarn group consisting of a plurality of carbon fiber bundles that are straight in practical terms and are aligned parallel to each other in a sheet shape. However, multiple
The carbon fiber bundles are arranged in layers so that the directions of the carbon fiber bundles intersect with each other between adjacent groups, and are woven with auxiliary yarns, and the auxiliary yarns are (a) a plurality of single yarns made of carbon fiber bundles; (b) has a ply twist; (c) has a fineness of 800 denier or less; (d) has a number of single fibers of 200 to 1,200; each of the above single yarns has (a> the above) (b)
The number of twists is in the range of 20 to 180 turns/m (7) and 0.1 to 0.8 times the number of ply twists, (c) the fineness of the single fiber is 0.5 denier or less, (d > Provided is a reinforcing base material for a composite material, characterized in that the elongation at break of single fibers is 2.5% or more.

In detail, the reinforcing base material of this invention is as follows:
It has a thread group consisting of a plurality of carbon fiber bundles arranged parallel to each other in a sheet shape.

Each carbon fiber bundle has no bends that would cause stress concentration,
It runs straight for practical purposes.

There are a plurality of threads 11Y, but approximately 2 to 4 threads are appropriate. Thus, each yarn group is arranged in a layered manner such that the directions of the carbon fiber bundles intersect with each other between adjacent groups. The intersection angle may be arbitrary, but is usually 90'.

The yarn group is woven with auxiliary yarns, and each carbon fiber bundle is restrained.

The carbon fiber bundles constituting the yarn group are composed of multifilaments having about 3,000 to 30,000 single fibers, depending on the diameter of the single fibers. This carbon fiber bundle is preferably twisted in 11tξ in order to improve the impregnating property of the matrix when forming the composite material 1. At most, 15
It is preferable that it is less than turns/m. In addition, the carbon fiber bundle is
The tensile strength measured according to the method specified in JIS R7601 is 300 mm2 or more, and the tensile modulus is 2
High strength, such as 3×103 Kg/mm2 or more,
Preferably, it is a high modulus carbon fiber bundle. (d3) The carbon fiber bundle, as well as the auxiliary yarn described later, may be provided with a noising agent.

Now, the auxiliary yarn that weaves the yarn group has a plurality of single yarns made of carbon fiber bundles, has a ply twist by plying, has a fineness of 800 deniers or less, and has a number of single fibers. is 200~
There are 1,200 pieces. Note that the number of single yarns that are twisted together is about 2 to 3.

The fineness of the auxiliary yarn is 800 denier or less, and the number of single fibers is 20.
The reason why the number is 0 to 1200 is as follows.

In other words, since the auxiliary thread is located behind the reinforcing base material, if it is thick, the irregularities on the surface of the base material and eventually the composite material will become large, making it easy to form areas with too much risk. It becomes impossible to obtain composite materials with excellent physical properties and reliability. Furthermore, if the auxiliary yarn is thick, it will bend the carbon fiber bundles that make up the yarn group, making it impossible to maintain them in a straight state for practical purposes. In order to avoid such inconvenience, the auxiliary thread should have a fat content of 800.
It must have a denier or less and the number of single fibers must be 200 to 1,200. Note that the lower limit of the fineness of the auxiliary yarn may be any value as long as it can withstand the weaving operation.

The single yarn constituting the auxiliary yarn must have a single fiber fineness of 0.5 denier or less and a breakage rate of 2.5% or more, preferably 3.5% or more. In other words, when using thick single fibers with a fineness of more than 0.5 denier, the stress generated by bending during weaving is large, making it impossible to effectively prevent single fiber breakage and the occurrence of strands. In order to prevent the occurrence of single fiber breakage and fuzz, it is not enough that the fineness must be 0.5 denier or less; it is also necessary that the elongation at break is 2.5% or more. In other words, when a single fiber is bent during weaving, tensile and compressive stress will occur in the single fiber at the same time. The occurrence of breakage and fuzz cannot be prevented unless the single fiber has a large elongation at break of 2.5% or more.

Here, the elongation at break of a single fiber is measured by a so-called single fiber loop test method. This method uses glycerin from 1 to
Place a single fiber on a glass plate with two drops so that it forms one loop, place a preparation on top of it, and pull both ends of the single fiber at a constant speed to break it while keeping the above loop in view with a microscope. This is the method of calculating from the following equation.

ε-1,066X (dt/d2)X100 However, ε
: Breaking elongation (%) dl: Diameter of single fiber (μm) d2: Average diameter of the loop just before breakage (μm) Auxiliary yarn is a yarn whose constituent single yarns are twisted in the opposite direction to the ply twist. , it is necessary to have a twist in the range of 20 to 180 turns/m and 0.1 to 0.8 times the number of ply twists. This relationship is important in that it restrains the single fibers to effectively prevent single fiber breakage and fuzzing, and also balances the untwisting torque given by the single yarns to the auxiliary yarns and the untwisting torque of the auxiliary yarn whites. In addition to preventing twisting of the auxiliary threads and facilitating weaving operations, and improving the reliability of composite materials by reducing the variation between products, they also have excellent mechanical properties. This is an essential requirement for obtaining composite materials.

When looking at an arbitrary fixed length of the auxiliary yarn, there is no variation in length between the individual yarns that make up the yarn, so-called yarn length difference, or if there is, it is within 0.1%. It is preferable that the By doing so, the force acting on the auxiliary yarn is applied uniformly to each single yarn, which not only prevents yarn breakage, but also improves the reliability and mechanical properties of the composite material. become able to.

The reinforcing base material of the present invention can be made into CFRP by, for example, impregnating it with a thermosetting resin such as epoxy resin or unsaturated polyester resin, followed by heating and pressure molding. Also, for example, phenolic resin, furan resin,
After impregnating pitch, etc., the resin, pitch, etc. are carbonized by heating and firing in an inert atmosphere to form CF.
It can be RC. Roughly, for example, CF is formed by laminating alternately with metal foil and press-molding at 1 nm heat.
It can be RM. The molding itself can be performed by a conventionally well-known method.

(Embodiment) In FIG. 1, the reinforcing base material includes a yarn group 4 formed by aligning a plurality of practically straight carbon fiber bundles 1 parallel to each other in a sheet shape, and also a plurality of For practical purposes, it has a yarn group 2 formed by pulling straight carbon fiber bundles 3 parallel to each other in a sheet shape. The yarn groups 2 and 4 are arranged in a layered manner so that the directions of the carbon fiber bundles 1.3 constituting them are perpendicular to each other, and the carbon fiber bundles 3 of the yarn group 2 are arranged in layers. The fibers are woven and held together by the auxiliary yarns 5 extending along the carbon fiber bundles of the yarn group 4 and the auxiliary yarns 6 extending along the carbon fiber bundles of the yarn group 4.

Note that, while the auxiliary thread 5 is crimped, the auxiliary thread 6 extends almost straight.

The auxiliary yarn 5.6 has an i degree of 800 deniers or less, a number of single fibers of 200 to 1200, and, as shown in Fig. 2, two of the single fibers have a fineness of 0°. 3, auxiliary yarn 5.6 having a single yarn 7.8 consisting of a carbon fiber bundle that must have a denier of 5 denier or less and a single fiber elongation at break of 2.5% or more,
Although it has a ply twist, each single yarn 7.8 also has a twist in the range of 20 to 180 turns/m and from 0.1 to 0.8 times the number of ply twists.

Therefore, the twist of the single yarn 7.8 is an S twist, but the final twist is a Z twist, and the twist direction is reversed.

In the embodiment described above, the case where there are two yarn groups has been described, but three or more yarn groups can also be similarly arranged in a layered manner. Further, the crossing angle of the carbon fiber bundles between the yarn groups is not limited to orthogonal, but can be arbitrarily selected.

(Effects of the Invention) The reinforcing base material of the present invention is a straight carbon fiber bundle for practical purposes, which can fully express its own characteristics because it does not have bends that would cause stress concentration. A group of yarns consisting of auxiliary yarns having a specific configuration, that is,
It has multiple single yarns made of carbon fiber bundles and has a fineness of 800.
denier or less, the number of single fibers is 200 to 1200, the single yarn has a twist in the opposite direction to the ply twist, the number of twists is in the range of 20 to 180 turns/m, and the ply twist number 0゜1
~0.8 times, the fineness of the single fiber is 0.5 denier or less, the elongation at break of the single fiber is 2.5% or more, and it is an auxiliary yarn with almost no single fiber breakage, fluffing, or twisting. Since it is made of a woven structure, it is possible to obtain a composite material with excellent mechanical properties such as strength and modulus of elasticity.

Furthermore, since the auxiliary yarn is also made of carbon fiber, the weather resistance, water resistance, heat resistance, etc. of the composite material are also improved. In general, the above-mentioned auxiliary threads also facilitate the weaving operation, making it possible to obtain a composite material that is not only reliable but also has small variations in properties between products.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing one embodiment of the reinforcing base material of the present invention, and FIG. 2 is a schematic front view of the auxiliary yarn shown in FIG. 1 above. 1: Carbon fiber bundle 2: Yarn group 3: Carbon fiber bundle 4: Yarn group 5: Auxiliary yarn 6: Auxiliary yarn 7: Single yarn 8: Single yarn

Claims (2)

[Claims] (1) A plurality of thread groups each consisting of a plurality of practically straight carbon fiber bundles, which are aligned parallel to each other in a sheet shape, are arranged such that the direction of the carbon fiber bundles is different between adjacent groups. They are arranged in layers so as to cross each other and are woven with auxiliary yarns, and the auxiliary yarns include (a) a plurality of single yarns made of carbon fiber bundles, and (b) a ply twist. , (c) the fineness is 800 denier or less, (d) the number of single fibers is 200 to 1200, and each of the single yarns (a) has a twist in the opposite direction to the ply twist, ( b) The number of twists is in the range of 20 to 180 turns/m and is 0.1 to 0.8 times the number of ply twists, (c) The fineness of the single fiber is 0.5 denier or less, (d ) A reinforcing base material for a composite material, characterized in that the elongation at break of single fibers is 2.5% or more. (2) A composite material having the reinforcing base material according to claim (1).