JPS63303732A - Extremely thin sheet - Google Patents

Abstract

PURPOSE:To obtain a carbon fiber-reinforced extremely thin resin sheet free from surging and a curl, by a method wherein a prepreg impregnated with resin is laminated on a sheetlike matter where carbon fibers of a specific length have been arranged unidirectionally, which is made at most a specific thickness by heating/pressurizing and curing the same. CONSTITUTION:A prepreg impregnated with resin is laminated on a sheet-like matter where carbon fibers of 3-100mm long have been arranged unidirectionally, which is heated/pressurized and cured and a carbon. fiber- reinforced extremely thin resin sheet of 3mm thick or thinner is obtained. The prepregs are laminated unidirectionally or by combining appropriately arranging angles of 0/90 deg. or 0/+45 deg. or -45 deg./90 deg. The prepregs arranged like this are pressurized by a heated press or an autoclave or under a bag vacuum accordance with characteristics of resin in use and made an extremely thin sheet of 0.3mm thick or thinner. With this construction, the extremely thin sheet free from surging or a curl is obtained without spoiling characteristics such as high strength, high elasticity and high durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a carbon fiber-reinforced ultra-thin plate having excellent flatness and used for thin plate springs, X-ray transmission plates, IC cards, and various other uses.

[Problems to be solved by conventional technology and invention]

Carbon fiber-reinforced ultra-thin plates have the following characteristics: high repeated bending fatigue strength, light weight and high rigidity, excellent X-ray transparency, electrical conductivity, and electromagnetic wave absorption properties. Various applications are expected, and specific examples thereof have been proposed (Japanese Utility Model Publication No. 145050/1983). However, when manufacturing ultra-thin plates, conventionally known prepreg (UD prepreg) impregnated with resin and unidirectionally aligned carbon long fibers is used.
It has been found that it is extremely difficult to avoid surface undulations, irregularities, and curves in products that are laminated and then pressed or autoclaved using conventional methods.

The inventors of the present invention have carried out intensive studies to develop an ultra-thin carbon fiber reinforced resin plate that is free from waving and curling. As a result, it has been found that the use of special unidirectional sheet Predeleg using short carbon fibers is effective against waving and curling. The present invention was achieved by discovering that it is possible to suppress the physical properties and exhibit high-level physical properties.

[Means for solving problems]

The gist of the present invention is to use a prepreg made by impregnating a V-shaped material with 5 to 100 square carbon fibers arranged in one direction alone or in combination with a resin-impregnated prepreg made of a unidirectionally aligned sheet of long carbon fibers. This is an ultra-thin sheet of carbon fiber-reinforced resin with a diameter of α5 or less obtained by laminating the sheets and curing them under heat and pressure.

A unidirectionally arranged sheet-like prepreg of 3 to 100 square carbon short fibers can be produced, for example, by the method described in JP-A-60-199996. The short fibers are arranged almost orthogonally to the

Specifically, polyacrylonitrile-based high-strength carbon fibers are cut to a predetermined length, dispersed in a dispersion solvent, and then continuously arranged on a P cloth using the centrifugal force of a rotating body, and then dried. It can be obtained by impregnating a thermosetting or thermoplastic resin in the form of a film or liquid film.

Further, the carbon long fiber unidirectionally aligned prepreg sheet, which is used in combination as necessary, is produced by a conventional method such as a hot melt method, a lacquer method, a film impregnation method, etc. on a continuous carbon fiber sheet.

The ultra-thin plate is formed by using the short carbon fiber unidirectional prepreg in one direction or at 0/90°, 0/+45°/-45°/906
etc., are laminated by combining the arrangement angles as appropriate.

At this time, in order to increase the flatness, it is recommended that the layers be arranged and stacked so as to have a symmetrical configuration with upper and lower mirror surfaces.

When using carbon long fiber unidirectional prepreg, a part of the short fiber prepreg is replaced with long fibers, and the fibers are arranged and laminated in a mirror-symmetrical manner.

The prepregs arranged in this manner are pressurized with a heated press or autoclave or under a bag vacuum depending on the characteristics of the resin used to obtain the ultra-thin prepregs of the present invention.

In order to obtain an ultra-thin molded product, the thickness of the prepreg mentioned above must be (
It is desirable to use a thin prepreg with a LO5mam or less, preferably a CLO25+m or less.

The matrix resins used include thermosetting resins such as epoxy, vinyl ester, polyester, phenol, and bismaleimide, as well as pp S 1PEA.

Thermoplastic resins such as PEEK, polyamide, polyester, etc. can be used.

Furthermore, the carbon fibers used are preferably high strength and high elasticity carbon fibers made from polyacrylonitrile, pitch, or the like.

〔effect〕

By using short carbon fiber unidirectional prepreg, the difference in molding shrinkage rate between the fiber and resin is absorbed by heating and pressure molding, resulting in an ultra-thin plate without distortion of the molded product, and without waving, warping, or carp. It can be used for cameras that require light weight, high rigidity, durability, and X-ray transparency. spring materials and other various spring materials, bleed surface materials for X-rays,
It can be used for various purposes such as protective plates, IC cards, calculator bottom springs, etc.

〔Example〕

The present invention will be specifically explained below using examples.

Example 1 Polyacrylonitrile-based high-strength carbon fiber (strength S 50
kg7m", elastic modulus 24 Ton/'min), are cut into approximately 6-mm pieces, dispersed in a dispersion solvent, continuously arranged in one direction on a P cloth using centrifugal force, dried, and made into a sheet-like material. By fusing and impregnating an epoxy resin film, a unidirectionally aligned carbon short fiber sheet prepreg having a thickness of 1025 m was obtained.

On the other hand, a carbon long fiber unidirectional sheet prepreg CB) having an αD of 25 m+thickness and fused and impregnated with an epoxy resin film was prepared for the carbon long fiber unidirectional sheet.

(:) The above-mentioned short fiber prepregs are laminated alternately so that the fiber orientation is 0°/90°10°, and by autoclave molding using a conventional method, a thickness a0 as shown in Fig. 2 is obtained.
An ultra-thin plate of 75 mm with excellent flatness was obtained.

This plate had excellent strength and elastic modulus, and was suitable as a grid surface material for X-ray wave regulation.

(11) An ultra-thin board with excellent flatness of a hybrid structure with a thickness αO of 75 m and a structure of 0°790°10°, by laminating short fiber prepreg in the middle layer and long fiber prepreg (A)) in the upper and lower layers. Obtained.

This flat plate had a high elastic modulus in the 0° direction, high strength, and high vibration durability, so it could be used as an excellent leaf spring for camera parts.

Comparative Example 1 Using only long fiber prepreg, 0°/90"70"
007 in the same manner as in Example 1 (1) by laminating alternately.
When an extremely thin plate of No. 5 was molded, the obtained flat plate developed waving and warping.

When this flat plate was used as a face plate for a grid or a leaf spring, the shape was unstable and its usage was limited.

Brief Explanation of the Eastern Plane FIG. 1 is a plan view of a unidirectionally arranged sheet of short carbon fibers used in the present invention, and FIG. 2 is a perspective view showing an example of an ultra-thin plate obtained by the present invention.

Claims (1)

[Claims] 1. Carbon fibers of 0.3 mm or less obtained by laminating resin-impregnated prepreg on a sheet-like material in which short carbon fibers of 1.3 to 100 mm are arranged in one direction, and curing under heat and pressure. Fiber-reinforced resin ultra-thin plate. 2. Prepreg (A), which is a sheet-like material in which carbon fibers with a fiber length of 3 to 100 mm are arranged in one direction and impregnated with resin; and prepreg (A), in which a sheet-like material in which long carbon fibers are arranged in one direction is impregnated with resin. An ultra-thin carbon fiber reinforced resin plate of 0.3 mm or less obtained by laminating B) in an arbitrary ratio and curing under heat and pressure.