JPH0578948A - Production of preform of three-dimensional woven fabric for composite material - Google Patents

Abstract

PURPOSE:To contrive the remarkable improvement in the productivity of a large three-dimensional composite article by forming reinforcing fiber bundles and the primary matrix having an excellent rod-forming property into rods, weaving the rods into a three-dimensional woven fabric preform and subsequently removing the primary matrix from the preform. CONSTITUTION:Rods are formed from reinforcing fiber bundles such as carbon fibers and the primary matrix such as an unsaturated polyester resin, a vinyl ester resin, a methyl methacrylate resin, an acrylate resin or a monomer, the primary matrix being selected on the consideration of its rod-forming property regardless of the matrix of the final composite article. The rods are woven into a three-dimensional woven fabric preform, and the primary matrix is chemically decomposed or dissolved off in the state holding the shape of the preform. The resulting preform is impregnated with the final objective secondary matrix to obtain a prescribed three-dimensional woven fabric composite article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a preform for a three-dimensional woven composite material, in which reinforcing fibers are three-dimensionally oriented.

[0002]

2. Description of the Related Art Unlike a composite material in which two-dimensional woven fabrics are laminated or a two-dimensional woven composite material, a three-dimensional woven composite material in which reinforcing fibers are orientated three-dimensionally and bonded is arranged in the thickness direction. As a result, it is expected as a material to which interlayer strength is imparted. As a technique for three-dimensionally weaving reinforcing fibers to produce this composite material, a method of directly weaving a three-dimensional woven fabric using reinforcing fiber roving is usually used. However, there are drawbacks such as damage to the reinforcing fibers during weaving and a slow weaving speed. Further, there are problems that it is difficult to make a large three-dimensional woven fabric and that the weaving density is low.

On the other hand, Japanese Patent Application Laid-Open No. 54-159489 discloses a technique for forming a pultrusion rod in which reinforcing fibers are impregnated with a thermosetting resin, and using this to weave a three-dimensional woven fabric. .. Further, Japanese Patent Laid-Open No. 2-169741 discloses an automatic device for weaving a rod into a three-dimensional fabric.

As a method for efficiently producing such a rod used for weaving a three-dimensional woven fabric, a resin as a base material of the composite material is impregnated into or mixed with a reinforcing fiber bundle, which is then passed through a mold. A so-called pultrusion method is suitable, in which a desired shape is formed by heating and solidifying. In this pultrusion method, both a thermoplastic resin and a thermosetting resin are used, but generally, the higher the physical properties such as the heat resistance of the resin, the slower the reaction rate and the molding rate, and the poorer the handleability becomes. , Therefore, the production speed becomes significantly slower.

Speaking of the FRP only, the resin filling the space between the filaments of the rod should be a resin having a high molding speed in consideration of the productivity of the pultrusion molding, and the resin filling the space between the rods should be poured. When molding, it is desirable to use a resin with a slow molding speed, but in selecting these resins and molding conditions, the compatibility of the resins is a composite material using a rigid rod as an intermediate material. It has a great influence on the physical properties of. Moreover, when the resin has high heat resistance and high performance, the resin has high viscosity, poor handleability, and slow molding speed.

Further, in a carbon matrix composite material such as C / C (carbon is abbreviated as C) and ceramics / C,
Thermosetting resins such as phenol resin and furan resin, which have good carbon yield, are used for the weaving rod, and polycarbosilane, etc., is used as the pultrusion resin for ceramic matrix composite materials such as C / ceramics and ceramics / ceramics. Although promising, pultrusion is difficult and slows production.

[0007]

SUMMARY OF THE INVENTION The technical problem of the present invention is that the primary base material of the rod is considered in consideration of formability regardless of the material that finally becomes the base material (secondary base material) of the composite material. And the final matrix of the composite material can be selected independently of the primary matrix of the rod, which makes it possible to easily and easily create a three-dimensional woven composite material using any reinforcing fiber and any matrix. It is to be able to easily manufacture.

[0008]

A method of manufacturing a preform for a three-dimensional woven composite material according to the present invention for solving the above-mentioned problems uses a rod formed by applying a primary base material to a reinforcing fiber bundle. It is characterized by weaving a three-dimensional woven fabric preform, removing the primary base material while maintaining the shape of the preform, and obtaining a composite material preform for filling the secondary base material. .. As a means for eliminating the primary base material, it is possible to use means such as incineration, chemical decomposition, chemical elution of the primary base material, or heat elution depending on the type of the base material.

Carbon fiber, glass fiber, boron fiber, silicon fiber, aramid fiber or the like can be used as the kind of the reinforcing fiber. If these fibers are used, they will be explained below by using an appropriate exclusion method. The preform for composite material can be obtained by eliminating such a primary base material.

As the primary base material for forming the reinforcing fibers into rods, any rod having excellent moldability and capable of being removed from the woven preform without damaging or deteriorating the fibers by appropriate means may be used. For example, if it is a thermosetting resin, a resin containing a radical polymerization prepolymer such as an unsaturated polyester resin, a vinyl ester resin, a methyl methacrylate resin, an acrylate resin or a monomer is most advantageous from the viewpoint of productivity and price. , Epoxy resin, urethane resin, phenol resin, bismaleimide resin, etc. can be effectively used. Of the thermoplastic resins, general-purpose resins such as polyethylene, polypropylene and polystyrene are most desirable, but engineered plastics and super engineered plastics can also be used depending on the application. Further, it may be a mixture of the above-mentioned thermoplastic resin and thermosetting resin, and may be a material other than resin as long as it is suitable as a primary base material.

The method for manufacturing a rod for weaving a three-dimensional woven fabric preform can be appropriately selected in consideration of the accuracy of the sectional size and shape of the rod, rigidity, productivity, cost, and the like.
The most advantageous method is the pultrusion molding method, but this method is suitable for continuous molding of molded products with a constant cross-sectional shape, and the cross-sectional shape of the molded product and the reinforcing fiber content are almost determined by the cross-sectional shape of the mold cavity and its dimensions. it can. When producing one pultruded rod per cavity, if the rod diameter becomes 1mm or less, it is difficult to thread the reinforced fiber roving into the cavity before production. It is preferable to use another suitable method because it requires much labor. When a thin rod is required as the rod, it is possible to produce a unidirectionally molded sheet in a wide cavity having a rectangular parallelepiped cross section and cut it into fine rods. Further, it is also possible to cut and use a molded product formed by laminating unidirectional prepregs.

In the pultrusion molding, a filler is added to the resin in order to improve the moldability, and this filler can be appropriately selected according to the application of the three-dimensional woven fabric. As the kind of the filler, particles such as calcium carbide, clay, and silicon carbide can be used when the filler may be left in the three-dimensional woven fabric. When the filler is not left, the powder of the thermoplastic resin or the powder of the cured thermosetting resin can be used as the filler. When finally obtaining a C / C composite, carbon black or the like may be used.

The cross-sectional shape and the reinforcing fiber content of the pultruded rod are appropriately selected according to the finally obtained reinforcing fiber content of the three-dimensional woven composite material. For example, in a three-dimensional orthogonal triaxial woven fabric, if the cross-sectional shape of the pultruded rod is square or rectangular, the fibers can be packed most densely, and when the reinforcing fiber volume content of the rod is 60% by volume, The reinforcing fiber volume content is 45%. On the other hand, considering the weavability of the rod, the cross-sectional shape is preferably circular.

When removing the primary base material of the three-dimensional woven fabric preform woven in a three-dimensional manner with a rod, the means for maintaining the shape of the three-dimensional woven fabric preform includes the firing temperature of the resin, acid, alkali, The three-dimensional woven fabric preform may be fixed with a holding fiber or film that does not disappear in a solvent or the like, or may be placed and fixed in a mold in the case of a complicated shape.

As the process conditions of the method for removing the primary base material of the three-dimensional weaving rod, it is necessary to select the conditions that the reinforcing fibers are not deteriorated and can be removed efficiently.
When the primary base material of the rod is a resin, in order to incinerate and remove the resin component, it is possible to easily incinerate by heating to 400 to 500 ° C in an oxygen atmosphere. This incineration temperature needs to be within a range where the reinforcing fiber does not deteriorate, and if there is no deterioration within the above temperature range,
A higher temperature can be applied. Further, the resin can be eluted by heat without incineration.

As a method of chemically decomposing the primary base material, an acid or an alkali is generally used at an appropriate temperature. Nitric acid, sulfuric acid and the like can be applied as the acid, and potassium hydroxide and the like can be applied as the alkali. Since the decomposition efficiency of some resins is poor, it is necessary to appropriately select the chemical material used for decomposition so that it is suitable for the decomposition of the primary matrix and does not cause deterioration of the reinforcing fiber. is there.

When the primary base material is chemically eluted, it is desirable that the primary base material is a thermoplastic resin. In this case, the resin can be easily eluted by selecting an appropriate solvent. For example, when the primary base material is polystyrene, there are many usable solvents, but methyl ethyl ketone can be sufficiently eluted. In any case, a solvent that efficiently elutes the primary base material and does not deteriorate the reinforcing fiber may be selected from various known solvents.

After the primary base material of the three-dimensional woven body is removed to obtain a preform for composite material, the preform is filled with the secondary base material. The secondary base material is CFRP.
When obtaining, epoxy resin, bismaleimide resin,
Thermosetting resin such as phenol resin and cyanate resin, thermoplastic resin such as polyimide, polyetheretherketone, polyetherimide, polybenzimidazole and polyparabanic acid are suitable, and a mixture of those thermosetting resin and thermoplastic resin. Can also be used. In addition, metals, ceramics, and carbon precursors (pitch, phenol resin, furan resin) can also be used, whereby a three-dimensional woven composite material of a metal base material, a ceramic base material, and a carbon base material can be obtained.

[0019]

As described above, when a three-dimensional woven fabric preform is woven using the three-dimensional weaving rod, and the primary base material is incinerated in an oxygen atmosphere or decomposed and eluted by chemical means to remove it from the woven fabric structure. It is possible to obtain a preform for a composite material that is composed of only the reinforcing fiber bundle. Therefore, it suffices to fill the preform for composite material consisting only of this reinforcing fiber bundle with the secondary base material, and without considering the compatibility between the primary base material and the secondary base material, etc. Can be easily filled.

[0020]

EXAMPLES Next, the present invention will be described in more detail by showing examples.

Example 1 Two 6000 filaments of carbon fiber Pyrofil TR-40 manufactured by Mitsubishi Rayon Co., Ltd. were used as reinforcing fibers, and a vinyl ester resin manufactured by Dainippon Ink and Chemicals, Inc. was used as a main resin for the resin of the primary base material. Dick Light UE
3505 using NOF Corporation NIPPER 6 as a catalyst
0, ASP made by Tsuchiya Kaolin Industry Co., Ltd. as a filler
400, 1x DuPont Zelec UN as a release agent
The mixture was used at a ratio of 00: 3: 1: 1 (weight ratio). The three-dimensional weaving rod was formed by impregnating the reinforcing fiber with the above-mentioned resin mixture and drawing it with a die having a cavity having a square cross section. Mold length is 250mm, cavity cross section is 0.82mm on one side, mold temperature is 170 ℃,
It was molded by pulling 10 rods at a drawing speed of 0.3 m / min.

This rod is woven into three-dimensional orthogonal three axes and 1
A three-dimensional woven fabric preform having a size of 00 mm × 100 mm × 100 mm was obtained. This preform was bound with a stainless wire and fixed, and fired in an electric furnace in an oxygen atmosphere for 2 hours to obtain a preform for a three-dimensional orthogonal triaxial composite material.

Example 2 The primary base material resin composition used in Example 1 was added to 5 parts by weight of the filler, and the same carbon fiber was used to form a pultrusion rod having a side of 0.88 mm by pultrusion to form a three-dimensional shape. An orthogonal triaxial woven fabric was woven to obtain a 100 mm × 100 mm × 100 mm square three-dimensional woven fabric preform. The circumference of this three-dimensional woven fabric preform was further wrapped with the above carbon fiber to fix the preform, and this was immersed in a 98% sulfuric acid aqueous solution heated to 220 ° C. for 30 minutes to decompose the resin component, and hydrogen peroxide solution was added. After adding, rinse thoroughly with water and dry in a dryer,
A preform for composite material was obtained.

Example 3 Using the resin for the primary base material used in Example 1 and the same 6000 carbon fibers as in Example 1, a pultruded rod having a circular cross section with a diameter of 0.64 mm was made, and the tip of the rod was attached. The woven fabric was reinforced by making it sharp and inserting it between orthogonal triaxial reinforcing fibers of the preform for composite material obtained in Example 2. A resin component was removed from this preform in the same manner as in Example 2 to obtain a three-dimensional woven fabric preform for a composite material having an increased reinforcing fiber density.

[0025]

According to the method of the present invention as described above, the primary base material of the rod is selected in consideration of formability regardless of the material which finally becomes the base material of the composite material, and the rod is also selected. The base material (secondary base material) of the final composite material can be selected irrespective of the primary base material in (2), and there is no need to consider compatibility between the primary base material and the secondary base material. As a result, it is possible to easily and easily manufacture a three-dimensional woven composite material using any reinforcing fiber and any secondary base material.

Further, although it was difficult to make a large-sized woven body with a conventional three-dimensional woven fabric for roving, according to the method of the present invention, since a rod is used for weaving the three-dimensional woven fabric, a large woven fabric is obtained. It is easy to obtain a woven body, and by using, for example, the automatic three-dimensional woven fabric weaving apparatus disclosed in Japanese Patent Laid-Open No. 2-169741, the productivity and production speed of a large dimensional three-dimensional woven fabric are dramatically improved. Can be planned.

Claims (4)

[Claims] 1. A three-dimensional woven fabric preform is woven using a rod formed by applying a primary base material to a reinforcing fiber bundle and removing the primary base material while maintaining the shape of the preform. A method for producing a preform for a three-dimensional woven composite material, which comprises obtaining a preform for a composite material for filling a next base material. 2. The method for producing a preform for a three-dimensional woven composite material according to claim 1, wherein the primary base material is incinerated as a means for removing the primary base material. 3. The method for producing a preform for a three-dimensional woven fabric composite material according to claim 1, wherein the primary base material is chemically decomposed and removed as a means for removing the primary base material. .. 4. The method for producing a preform for a three-dimensional woven composite material according to claim 1, wherein the primary base material is chemically eluted to be removed as a means for removing the primary base material. ..