FR2653141A1 - COMPOSITE MATERIAL AND ITS MANUFACTURING METHOD. - Google Patents

Abstract

Composite material of substantial thickness, characterised in that it consists of a single set of strands which are woven in three dimensions, the said set being resin-coated.

Description

The present invention relates to a material

  composite and its production method.

  The composite material is a heterogeneous substance generally comprising fibers, threads, free or assembled in layers, embedded in a resin. These composite materials are generally in the form of large, fairly rigid thick plates. They are used more and more in the industry, in particular in the industry of construction of equipment, capital goods, transport, etc. for making bodies, floors, etc. These plates are transformed, according to traditional techniques by contact or vacuum molding, by injection and according to a more technical

recent, by stamping.

  Generally, a production process consists in assembling in layers or strata textile fabrics of fibers or reinforcing threads with high mechanical characteristics such as: glass, silica, silicon carbide, carbon, ceramic, aramids, high modulus polyethylene, etc., and to drown them in a resin matrix. More precisely, a base of resin and release agent is poured into a mold the size of a plate; above, a first layer of fabric is laid, made of reinforcing fiber threads for example, which is covered with resin; above, a second layer of fabric is placed in high-resistance reinforcing threads, which are also covered with resin; so on, several layers are stacked, for example five or six, which are covered with resin, and the stack is completed with a last layer of resin and a release agent. This assembly is then subjected to a compression action intended to eliminate the maximum of air and to make the resin penetrate into the layers of fabrics, then a heat treatment which crosslinks or polymerizes the resin in order to obtain a rigid composite and as homogeneous as possible. These composite materials can comprise up to more than forty layers each with a thickness of the order of 0.1 to 0.2 millimeters; the most common have one & fifteen layers and are of average total thickness between 3 and 5 millimeters after compression and ready to use. Their weight is of the order of 200 grams / m2 for a layer 0.1 mm thick in glass. The material obtained is a composite product & high resistance in particular to shocks,

traction, compression.

  However, such a process has many drawbacks: 1- it is expensive: the material necessary for its mechanization is very expensive, and generally the

  operations are manual, which requires a manual

  important work; on the other hand it is long: the stages of realization are numerous; 2- the material obtained has a low

  shear strength: delamination is observed.

  The phenomenon is explained by the fact that the layers of tissue contain air bubbles which are not expelled by the resin. These bubbles form as many

  small air mattresses that reduce diaper contact

  resin and adhesion between layers.

  3- the homogeneity sought by the heat treatment (impregnation, polymerization) is difficult to obtain in a reasonable time, due to the thickness of the material which accentuates the

friend swims.

  On the other hand and in a very general way, a fabric is a textile structure formed by an assembly of so-called warp threads assembled in so-called weft threads. This structure extends in a plane, the thickness of which is limited to that of the wire or wires used, a negligible dimension relative to the surface of the fabric. One of the usual characteristics of fabrics is their non-deformability in the plane, which can be a quality or a defect depending on the use made of them. It is well known that the deformation of a fabric to give it a shape produces folds, the fabric not being capable of deforming elastically due to its structure. Confection is then the art of assembling pieces of fabric so as to hold shapes, whether in the clothing industry or any other industry. This is why, when making composite materials, assembling the layers of fabrics also consists in arranging strips of fabrics so as to promote the production of shapes, without producing folds. The present invention aims to producing a composite material according to a process which resolves all the difficulties presented: mechanization, speed of production, high deformability, resistance to delamination, homogeneity, costs. The subject of the invention is a composite material of substantial thickness, characterized in that it consists of a single set of reinforcing threads associated with a thermosplastic resin, woven in three dimensions. It also relates to the use of a weaving loom provided with several chains of reinforcing threads in order to produce a composite covering.

of substantial thickness.

  In order to better understand the invention, a non-limiting example of

material according to the invention.

  As can be seen in the drawing, the fabric 1 comprises several series of 2 warp threads 2 extending parallel to each other. In the example, the fabric has 5 series of warp threads 2a & 2f. Each chain is horizontal, the series overlap vertically, forming a thick sheet, which extends in three dimensions. The weft threads 3 are passed alternately through these warp threads and. according to the choice, alternate between the wire of the first level 2a and the wire of the second 2b, or of the third 2c etc. The weaving can be modulated according to the effect that

we want to give to the fabric.

  Such a process gives a thick, homogeneous fabric

  in its thickness since made in one piece.

  On the other hand, the fact of weaving in three dimensions gives this fabric great deformability, by

internal deformation.

  In a first variant of embodiment,

  wires are previously associated with the resin, that is

  say that they include both reinforcing fibers and their matrix or resin. This "entrainment" is obtained either by intimate mixture in the wire, of reinforcing fibers and of resin presented in the form of fibers, or by coating of reinforcing wires with a sheath of resin. In a second variant, weaving is carried out with threads comprising only reinforcing fibers, free of resin. The son-resin association, or "enresinement" is here a coating of the fabric; it is produced after passing through the loom by application with a brush, spraying, injection, or

any other known technique.

  The first variant is advantageous in that it gives, in a single operation, a flexible material which can be immediately wound up, or cut into panels, and constitutes a finished product ready to be used. The coating obtained must then undergo a heat treatment followed or not by compacting intended to melt the resin, & give this coating the desired shape and then give it a

great rigidity.

  As an example of an embodiment, a three-dimensional fabric was produced with composite yarns comprising% glass, 40% PEEK, and the heat treatment and a

  stamping gives armor plates.

  The invention provides, among other things, the following considerable advantages: the three-dimensional assembly is perfectly homogeneous; - deep weaving removes successive layers, there can no longer be delamination; - after heat treatment the presence of air bubbles between the woven threads has no adverse influence on the resistance characteristics: this operation can then be considerably

simplified.

  - The material can be more or less compressed which makes it very easy to make imprints which remain flexible; - the material is very light; compared to traditional materials & comparable thickness. We can estimate a weight gain of around 20%

Claims (4)

  1. Composite material of substantial thickness characterized in that it consists of a single set of three-dimensional woven threads, said all being coated with resin.   2. A method of producing the material according to claim 1 characterized in that the reinforcing threads are previously associated with a thermoplastic resin. 3. A method of producing the material according to claim 1 characterized in that in a first operation weaving is carried out with threads with high mechanical characteristics, then impregnated with resin, the fabric produced.   4. Use of a weaving loom provided with several chains of reinforcing threads in order to produce   a composite coating of substantial thickness.