IE52329B1

IE52329B1 - A method for the production of woven laminates

Info

Publication number: IE52329B1
Application number: IE409/82A
Authority: IE
Original assignee: Fothergill & Harvey Ltd
Priority date: 1981-02-26
Filing date: 1982-02-25
Publication date: 1987-09-16
Also published as: FR2500360B3; GB2093768B; IT8247868A0; AU8078982A; CH645842A5; IT1147815B; GB2093768A; NL8200744A; DE3206072A1; ZA821181B; IE820409L; FR2500360A1; IL65129A0; SE8201173L; BE892268A

Abstract

A mouldable laminate is made by weaving plies from fabric fibres comprising a proportion of thermoplastic fibres, assembling a plurality of the plies and heating the resultant assembly under pressure, the thermoplastic fibres bonding the plies together and improving the mechanical and other properties of the laminate. The proportion and type of thermoplastic fibre and the number of plies used depends upon the properties required for the intended use of the laminate.

Description

This invention relates to an improved method for the production of woven laminates and laminates produced thereby and more particularly to the production of woven reinforced thermoplastic laminates either in the form of flat panels br curved pieces.

Laminates as described have previously been made by interleaving woven fabric with a thermoplastic matrix in film or particle form and subsequently heating the assembly under pressure.

The disadvantages of this method are that the thermoplastic films or particles are difficult to handle and can be difficult to manufacture. Moreover, in laminates where a discontinuous layer of thermoplastic material is desirable the manufacture becomes very complex - 2 The thermoplastic materials ln question are, however, readily available in the form of textile fibres.

According to the invention, the method comprises weaving a fabric of reinforcing yarn and of thermoplastic yarn, assembling a plurality of plies of said fabric one above the other, and heating the assembled plies under pressure to produce the mouldable composite laminate, the number of plies used in the composite laminate depending upon the performance requirements of the end use, the thermoplastic yarn serving to bond the plies together to improve the mechanical and other properties of the composite laminate.

Preferably the reinforcing yarn consists of carbon fibres, or glass fibres or aromatic polyamide fibres and the thermoplastic yarn consists of fibres of polyolefine, polyester, polyamide, polyether, sulphone, or polyether ether ketone.

This invention thus proposes the weaving of a single fabric which incorporates both the reinforcing fibre and the thermoplastic matrix in fibre form.

In designing such a fabric there are a multitude of base fabrics which may be selected according to the end use intended. The choice of reinforcing fabric is according to the mechanical, heat resistance, chemical resistance, electrical and other such proper52329 - 3 ties required in the final product. Similar considerations are involved in the selection of the type, quantity and distribution of the thermoplastic fibre. When these parameters have been established the two are brought together to provide a fabric which is essentially the reinforcing fabric with extra threads Consisting of the thermoplastic matrix material in filament form.

These extra thermoplastic yarns may be either warp 10 or weft or both. Plies of this single fabric are then heated under pressure to melt the thermoplastic filaments which, upon cooling, bond the reinforcing fabric layers together.

It is also possible to moke a fabric where the 15 warp consists entirely of reinforcing fibres and tl.o weft entirely of thermoplastic fibres or vice-versa. Plies of sucli a fabric when placed one on top of another in the same orientation will produce a socalled uni-directional laminate which has all the reinforcing fibres in one direction only. Such a fabric can also be used to form multi-directional laminates by orientating the reinforcing fibres as required during the laminate preparation. 53328 - 4 The invention will be described further, by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a diagrammatic sketch of one example 5 of a fabric used in the method of the invention and liavinc 75^ of the warp a of a thermoplastic fibre such as polythene on one side and 25?. on the opposite side as well as warp a' and weft b of reinforcing fibre such as aromatic polyamide fibre; Fig. 2 is a diagrammatic sketch of another example of a fabric which may be used in the method of the invention and has thermoplastic warp fibres a equally distributed on both sides of aromatic polyamide warp and weft yarns a’ and b respectively; Fi·;. 3 is a diagrammatic sketch of a third sketch of a third example of a suitable fabric which simply has thermoplastic warp yarns a and aromatic polyamide weft yarns b; and Fig. 4 shows a fourth type of fabric which may be used in the method of the invention and has a satin weave (allowing greater permeability and easier draping - 5 than a plain weave) and having thermoplastic and aromatic polyamide warp yarns a, respectively and reinforcing and thermoplastic weft yarns b, b' respectively.

A commonly used fabric for plastics reinforcement 5 is a plain weave fabric witli 67 threads per 100mm in both warp and weft directions consisting of aromatic polyamide fibre a1 , b and thermoplastic warp yarns a (Fig. 1).

For the production of a 25ram thick laminate consist10 ing of 155° by weight polythene and 85?’ by weight aromatic polyamide (or carbon or glass) reinforcing fibre, the procedure is the following:For the sake of economy it is convenient to introduce the poLythene as warp a, thread for thread, with the aromatic polyamide warp and weft fibre fi', b.

The linear density of the polythene warp is therefore 305-1 that of the aromatic polyamide since the weights of aromatic polyamide in the warp a.1 and weft I) of tho base fabric are equal. Such a yarn is a 0.25mm high density polythene monofilament and may be introduced into the fabric as illustrated, although there are many possible weave variations. - 6 To produce a 25mm thick laminate from the fabric of Fig. 2, 85 plies are placed one on top of the other and placed in a press with pressing plattens heated to 150°C or to a higher temperature when dealing with other material. When the polythene has melted, a pressure of approximately IMPa (150 psi) will consolidate the laminate to 25mm thickness or alternatively stops at 25mni spacing can be used in the press. After pressing the laminate is cooled either in or out of the press.

Phe choice of reinforcing and thermoplastic fibre and the pressing conditions depends upon the end use for which the laminate is intended, as does tbe ratio of tne respective fibres.

The reinforcing fibre is preferably carbon, aromatic polyn.ii.de or glass fibre which arc all of liigh strength and high modulus.

The thermoplastic fibre is preferably polyolefine, polyester, polyamide, polyether sulphone or polyotlier ether ketone.

Other reinforcing and thermoplastic fibres may however be used - 7 The advantage of the above-described fabric weaves is that it is possible to manufacture laminates without crimp in the reinforcing fibres.

A further advantage of the method of the invention 5 is that the production of curved laminates is facilitated Simple curvatures may be made by forming them from a flat laminate before the thermoplastic material solidifies. More complete curvatures can be made by selecting a fabric weave such as satin (t'ig. 4) capable of draping round a curved mould prior to pressing.

A further advantage is that high reinforcing fibre content laminates are easily and economically produced and it is possible by using normal textile machinery to melt the thermoplastic filaments either partially or completely. This has the effect that ihe thermoplastic material is not only interwoven with the reinforcing fabric but also bonded thereto. This can be an advantage in the preparing of the laminate lay up before moulding in that it reduces the risk of 2o fraying of reLnforcing fabric during the tailoring operation. Similarly, if cutting methods by ultrasonic or laser techniques, which produce heat, are used, the thermoplastic threads which are cut tend to fuse and again seal the edges. 52339

Claims

CLAIMS 1. A method of producing a composite woven fabric laminate comprising weaving a fabric of reinforcing yarn and of thermoplastic yarn, assembling a plurality of plies of said fabric one above the other, and 5 heating the assemblied plies under pressure to produce the mouldable composite laminate, the number of plies used in the composite laminate depending upon the performance requirements of the end use, the thermoplastic yarn serving to bond the plies together to Improve the mechanical and other properties of the composite laminate, 2. , A method of producing a composite laminate as claimed in claim 1 wherein the reinforcing yam consists of carbon fibres, or glass fibres, or aromatic poly15 amide fibres. 3. , A method of producing a composite laminate as claimed in claim 1 or 2 wherein the thermoplastic yarn consists of fibres of polyolefine, polyester, polyether sulphone, or polyether ether ketone. 20 4. A method of producing a composite laminate as claimed in any preceding claim, in which the reinforcing -9yarn and thermoplastic yarn are employed as warp yarns and/or weft yarns. 5. A method of producing a woven laminate substantially as hereinbefore described. 56. A composite laminate when produced by the method of claim 1, 2, 3 or 4 substantially as described with reference to the accompanying drawing.