GB2117020A

GB2117020A - Reinforcement for plastics mouldings

Info

Publication number: GB2117020A
Application number: GB08207880A
Authority: GB
Inventors: Shigezi Hasegawa; Tadashige Yamaguchi; Yatsuhiro Hasegawa; Shigekazu Hasegawa
Original assignee: Hasegawa Chemical Industry Co Ltd
Current assignee: Hasegawa Chemical Industry Co Ltd
Priority date: 1982-03-18
Filing date: 1982-03-18
Publication date: 1983-10-05

Abstract

A woven or non-woven reinforcement for plastics mouldings includes metallic threads which enable the reinforcement to be easily formed into a desired shape and to maintain the shape into which it is formed. For example, in a woven cloth the warp 12 may be of glass fibres or carbon fibres and the weft 14 may be wholly or partly of fine threads of stainless steel, steel, brass or copper. <IMAGE>

Description

SPECIFICATION Reinforcement for plastics mouldings This invention concerns reinforcement for use in plastics mouldings.

Reinforcement for plastics is used in order to reinforce the strength of resins in producing plastics products such as plastics skis, boats and bath-tubs. The reinforcement is moulded together with a resin so as to be embedded in the resin.

Such reinforcement includes that of the fibre type wherein glass fibres or carbon fibres are used as they are, the woven cloth type in which these fibres are woven into a cloth and the non-woven cloth type in which these fibres are not woven but are formed into a mat.

Up to the present, the problem in producing plastics products using such reinforcements has been that it was difficult to form them into a predetermined shape in such a way that they were maintained in that shape. In order to increase the strength of plastics products while maintaining their light weight, it is necessary to form the reinforcement into a desired shape, e.g. a U-shape, cylinder-shape, convex shape or wave-shape, before it is moulded into the resin. Furthermore, in the case of boats and bath-tubs, it is also required that the reinforcement should be easily formable to the desired contour and should retain the shape into which it is formed.

According to the invention, this requirement is achieved by the inclusion of metallic threads in the different types of reinforcement referred to above.

Thus if the reinforcement is of the woven type the metallic threads may form part or all of the warp or the weft, or both, and if of the non-woven type, the metallic threads are embedded in the other fibres.

Reinforcement in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:~ Figures 1 to 3 are schematic views of different forms of reinforcement; Figures 4(1) to 4(6) are schematic views of reinforcement for use with plastics skis.

The reinforcement 10 shown in Figure 1 is in the form of a woven cloth consisting of a warp 12 comprising reinforcing fibres such as glass fibres or carbon fibres and a weft 14 comprising fine metallic threads of stainless steel, steel, brass or copper. By using as the weft 14 metallic threads which exhibit high plasticity as well as the property of maintaining the shape into which they have been once formed, the reinforcement 10 can easily be shaped as desired before it is incorporated in resin mouldings. However, the Young's modulus of a metallic thread is smaller than that of a glass fibre or carbon fibre. Therefore, when only metallic threads are used as the weft 14, the final moulded resin products, e.g. plastics skis, boats, bath-tubs and so forth, may lack rigidity and have insufficient twist-resistance.

Also, since the coefficient of linear expansion of a metallic thread is higher than that of a glass fibre of carbon fibre, some dimensional error along the weft may occur during the heating process. In order to overcome these defects, it is possible to use a combined weft which consists not only of metallic threads but also of some glass fibre threads or carbon threads as well. It is also possible to use as the weft, metallic threads and either glass fibre threads or carbon fibre threads alternately or at desired pitches.

The width W and length L of the reinforcement 10 can be determined in accordance with the final products that are to be moulded. The pitches P1 of the warp 12 and P2 of the weft 14 can also be determined accordin#g to specific uses. By selecting relatively large values for P, and P2, spacing 16 can be produced. When the reinforcement 10 is used with expandable urethane products such as plastics skis, these gaps 16 can serve as openings through which the urethane can easily expand. Thus, the reinforcement 10 is excellent for use with expandable urethane products.

The basic structure of the reinforcement 10' shown in Figure 2 is almost identical to that of the reinforcement 10 shown in Figure 1. Therefore, the respective components in this Figure are indicated with the same numerals (but with primes) as the corresponding components of the first Figure.

This reinforcement 10' differs from the reinforcement 10 in Figure 1 in that the warp 12' is hardened or semi-hardened by preimpregnation with either a thermo-plastic resin such as epoxy, polyester, phenol or melamine or with a thermo-elastic resin such as A.B.S., polyethylene or polypropylene. Thus, because the warp 12' is hardened or semi-hardened to a greater degree than the reinforcement 10, the reinforcement 10' has the advantages of easier handling as well as a further increase in the strength of the final products. As in the first embodiment in Figure 1, the warp 14' may consist not only of metallic threads but also of glass fibre threads or the like and these two kinds of threads may be woven alternately or at desired pitches.

In the embodiments shown in Figures 1 and 2, metallic threads are used only in the weft.

However, depending on the intended use, it is possible also to use metallic threads in the warp in an appropriate ratio.

Figure 3 shows in cross section a third embodiment of reinforcement, which unlike the embodiments of Figures 1 and 2, is made of nonwoven cloth.

The non-woven cloth constituting the reinforcement 20 consists of short reinforcing fibres 22 such as glass fibres or carbon fibres or the like among which short metallic threads 24 are arranged randomly. The density of the reinforcing fibres 22 of glass fibres or the like and that of the metallic threads 24 can be varied according to intended use. Like the reinforcements shown in Figure 1 and 2, the reinforcement 20 can be shaped as desired and will retain the shape into which it is formed because of the metallic threads.

Figures 4(1) to 4(6) are schematic cross sectional views of skis of expandable urethane resin in which reinforcement in accordance with the invention as shown in Figures 1 to 3 is formed into various shapes. The structure of metal moulds 30 in each of the six views of Figure 4 is shown in simplified form. In practice, the metal moulds 30 are divided into a metal mould proper and a mould compressing plate. The metal mould itself contains the necessary parts of a ski such as an edge and gliding side plate and is sealed from above by a top plate (not shown) and a compressing plate. By expanding the expandable urethane 32 within the metal mould, the gliding plate, top plate and edge are all moulded into one body. Since expandable urethane is not strong, various methods of reinforcement have been used in the past.

Skis made of expandable urethane are characterised by their light weight. Therefore, the reinforcement to be added should be as light as practically possible to minimise the total weight of the skis. Therefore the reinforcement 34 should be moulded into one body with the expandable urethane, while, at the same time, maintaining its original shape in such a way that it provides good reinforcing effect.

As reinforcements 34 for plastics skis, various shapes have been devised as shown in (1) to (6) of Figure 4. With conventional reinforcement in which metallic threads are not used, it is extremely difficult to mould the ski while retaining the original shape of the reinforcement as shown. This is because: (1) conventional reinforcement consists entirely of either glass fibres or carbon fibres and soon loses its shape after being formed into the desired shape before being put in the metal mould.

(2) it is impossible to put a support in the metal mould in order to prevent the reinforcement from losing its shape. Up to the present, in order to prevent reinforcement from losing its shape, the reinforcement was either pre-impregnated with resin and then hardened with heat, or was stuck with an adhesive at several points. However, these methods have disadvantages: the former increases the production cost of skis because it requires heat-hardening processes in order to form the reinforcement into the desired shape, while the latter does not effectively prevent the reinforcement from losing its shape in spite of the troublesome sticking work.

Reinforcement in accordance with the present invention overcomes all these defects of conventional reinforcement. Thus the presence of easily formable metallic threads eliminates the heating and moulding processes required to form the reinforcement into a desired shape. Also, the desired shape is maintained without sticking the reinforcement with an adhesive.

Although Figure 4 shows the reinforcement in accordance with the present invention as used in reinforced plastics skis, such reinforcement can also be used for other plastics articles such as boats and bath-tubs, and in such cases it will greatly increase the efficiency of moulding because it can easily be formed to the complicated contour of these products.

Claims

1. Woven cloth-like reinforcement for use in plastics mouldings in which either the warp or the weft of the reinforcement or both comprises metallic threads and the remaining fibres consist of reinforcing glass fibres, carbon fibres or the like.

2. Woven cloth-like reinforcement for use in plastics mouldings in which either the warp or the weft of the reinforcement or both consist of metallic threads and glass fibres, carbon fibres or the like and the remaining fibres (if any) consist of glass fibres, carbon fibres or the like.

3. Reinforcement for use in plastics mouldings in which metallic threads are embedded in a nonwoven cloth made of glass fibres, carbon fibres or the like.

4. A plastics moulding reinforced with reinforcement according to any one of the preceding claims.