JPS5820781B2 - Method for preventing and controlling the fiber-removal of fiber-removal materials - Google Patents

Description

DETAILED DESCRIPTION OF THEINVENTION The present invention relates to a method for optionally controlling the fiber orientation of short fibers when producing a short fiber reinforcing aggregate substrate for use in a fiber-reinforced composite material.

Fiber-reinforced composite materials are used in a variety of applications, and known types of reinforcing fibers include carbon fibers, glass fibers, synthetic fibers, and natural fibers.

Known fiber forms for substrates for fiber-reinforced composite materials include uniaxially or biaxially aligned anisotropic substrates made of continuous fibers such as rovings, strands, and yarns, or spun yarns, or knitted or woven fabrics made from these materials, mat-like dispersed isotropic substrates made of short fibers or short fiber bundles, unidirectional substrates made by a papermaking method, swirl mats in which continuous fibers are arranged in a disordered thin pattern, and pseudo-isotropic substrates made by laminating various substrates.

Among these fiber-reinforced composite material substrates, conventional mat-structure substrates, such as chopped strand mats and surface mats made of glass fibers, have fibers arranged at random, and are macroscopically isotropic substrates. However, microscopically, there is a very large variation, and depending on the application, the non-uniformity of the material properties may become a drawback.

Furthermore, a mat-structured substrate made of short fibers or short fiber bundles can produce an isotropic substrate with a much thinner thickness than a woven or woven substrate made of continuous fibers, but conversely, it is difficult to produce a unidirectional substrate that more symbolically exhibits the properties of the reinforcing fibers.

Methods have been proposed for producing unidirectional base mats from short fibers or short fiber bundles, including those that utilize air flow and those that utilize liquid flow. However, those that utilize air flow require advanced technology and equipment, and those that utilize liquid flow have the disadvantage that they are limited to fiber lengths of approximately 10 mm or less.

The object of the present invention is to provide a simple method for controlling the orientation of short fibers, from uniaxial to multiaxial, as desired, when producing a mat- or sheet-shaped fiber-reinforced composite material substrate.

This invention relates to a method for controlling fiber orientation when supplying short reinforcing fibers to produce a fiber-reinforced composite substrate by sliding the short reinforcing fibers down a number of grooved inclined plates arranged side by side with the lines of the bottom of the grooves offset from each other.

The form of the fiber-reinforced composite material substrate is suitable for producing a mat or sheet-like product, and the short fibers may be either separated into single fibers or in the form of short fiber bundles.

The present invention will now be described with reference to the drawings.

FIG. 1 is a perspective view showing the principle of the method of the present invention;
The figures are longitudinal side views showing the state in which the method of the present invention is being carried out, FIG. 3 is a cross-sectional view illustrating the shape of the grooves in a grooved plate, FIG. 4 is a plan view and a front view of the grooved plate showing the fiber orientation effect, and FIG. 5 is a sketch illustrating the shape of a grooved plate for isotropically orienting the fibers.

The grooved plate 1 is inclined and placed on the endless belt-like fiber collecting zone 3.

The inclination angle of the grooved plate 1 is 90 degrees or less, and is preferably in the range of 40 to 60 degrees.

The short fibres or short fibre bundles 2 are dropped onto the upper part of the grooved plate 1 .

The short fibers or short fiber bundles 2 slide down the grooved plate by gravity and have their orientation controlled along the bottom of the grooves.

The grooved plate 1 may be of a fixed type, but if it is subjected to slight vibration, the orientation of the fibers can be performed quickly and reliably.

The arrangement of fibers on the continuous collection zone 3 is determined by the pitch of the grooves in the grooved plate. In order to achieve uniform density, in this invention, as shown in FIG. 2, a number of inclined plates 1a, 1b, etc. are used and arranged side by side with the lines of the groove bottoms of each grooved plate offset from each other.

With this configuration, for example, different types of fibers, such as carbon fiber and glass fiber, can be mixed and arranged.

The groove shape of the grooved plate 1 can be a mountain shape, a wave shape, a trapezoid shape, or a mixture of these shapes, but the opening width of the groove is preferably at least wider than the fiber length and narrower than twice the fiber length.

As shown in FIG. 3A, when the groove has a flat portion at the valley portion, the width of the flat portion is at least wider than the thickness of the fiber.
It must be narrower than the fiber length.

Therefore, as the fiber length of the fibers used increases, the groove width of the groove plate must be widened. When using fibers with long fiber lengths, the number of valleys may be increased by dividing the grooves, as shown in FIG. 3, in order to prevent the fiber arrangement from becoming too coarse.

The fiber orientation control effect on the fibers sliding down the grooved plate is as follows.

As shown in FIG. 4, the fibers 2 that fall onto the grooved plate 1 are
It slides downward from position a, passes through position b, and reaches position C, where it is oriented along the valley of the groove.

In order to make the fiber orientation of the mat structure unidirectional, it is preferable to configure the grooved plate in a flat plate shape. However, in order to make the fiber orientation isotropic, it is preferable to configure the grooved plate in a conical shape as shown in FIG. 5A.
By using a grooved plate having a rudder shape as shown in FIG. 5B or a shape obtained by cutting either of these in half and reciprocating it, an isotropic substrate can be produced continuously.

The present invention makes it possible to arbitrarily control fiber orientation from uniaxial to multiaxial by simple means.

Short reinforcing fibers include carbon fiber, glass fiber, asbestos, ceramic, poron, and various metal fibers such as stainless steel, aluminum,
It is possible to use inorganic fibers such as copper and nickel fibers, organic synthetic fibers such as nylon, polyester and polyvinyl fibers, or a mixture of two or more of these fibers in an appropriate ratio.

The length of the short reinforcing fibers is generally 3 to 100 mm, preferably 20 to 50 mm.

When the reinforcing short fibers are used as a short fiber bundle, the number of fibers in the bundle is usually 50 to 5,000, preferably 200
About 3,000 deer stalks are good.

The material of the grooved inclined plate used in the present invention is not particularly limited, and may be any suitable material such as iron, tinplate, plastic, etc., but aluminum, stainless steel, etc. are preferred.

In this specification, a mat refers to a relatively bulky material that has its shape maintained by a small amount of binder and other mechanical means such as pressing or needle punching, and a sheet refers to a relatively dense structure, such as a paper or prepreg-like material, that is formed by a large amount of binder and resin.

The mats and sheets obtained by the present invention are suitable as base materials for composite materials for boats, chemical equipment, mechanical materials, and the like.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the principle of the method of the present invention;
The figures are a longitudinal sectional side view showing the state in which the method of the present invention is carried out, Fig. 3 is a cross-sectional view showing an example of the shape of the grooves of the grooved plate, Fig. 4 is a plan view and a front view of the grooved plate showing the fiber orientation effect, and Fig. 5 is a sketch showing an example of another shape of the grooved plate. 1: grooved plate, 2: short fiber, 3: fiber collection zone.

Claims (1)

[Claims] 1. A method for controlling fiber orientation in a fiber-reinforced composite substrate, characterized in that when short reinforcing fibers are supplied to produce a fiber-reinforced composite substrate, the fiber orientation is controlled by sliding the reinforcing fibers down a plurality of grooved inclined plates arranged side by side with the lines of the groove bottoms offset from each other.