This invention relates to a method for manufacturing a three-dimensional textile product obtained in the form of a knitted fabric, a woven fabric or a technique suited therefor

Textile products of the intended type are thoroughly described i a in patent application PCT/BE93/0048 They can be used as such or as reinforcement in composite materials Three-dimensional knitted fabrics or three-dimensional woven fabrics, as described in this application, specifically show a certain indentation stiffness, in other words a resistance against a movement of both woven or knitted fabric surfaces towards one another, which characterise these textile products It will be noted in passing that, besides knitted and woven fabrics, three-dimensional textile products can also be produced by braiding, tufting, sewing, etc In the following description and claims, these different techniques will therefore be clarified by the expression "textile processing The stiffness of the textile product is mainly dependent of the stiffness of the used pile thread, of the density of these pile threads and of the crossing, i e perpendicular, obliquely or in section relation, as well as of the height of the pile threads, i e the distance between both of said surfaces of the textile product

ln order to increase the stiffness of a three-dimensional textile product for a given pile height, use is made of a stiffer thread or a higher density of these pile threads is applied, and this with the adequate crossing. By this way of treatment, one is however faced with several problems, the most important of which can be described as follows : the higher the stiffness of the pile thread, the worse the weaving or knitting properties of the product, i.e. with the hereinabove mentioned textile treatment. When applying other production possibilities, the application of pile threads of this too high stiffness has also very adverse consequences.

An object of the invention is to provide textile threads, i.a. pile threads, which are sufficiently flexible and which can thus be applied in high densities. With a finishing treatment which pertains to the essence of the invention, the threads, i.a. the pile threads, are stiffened without having to fill up the distance between the above mentioned surfaces of the textile product, for example with foam.

In the following examples, pile threads, their structure, their preliminary and finishing treatment will be described and this in function of the essential role which has to be fulfilled by these pile threads in a three-dimensional textile product of the hereinabove described type. On the other hand, textile threads which do not have the function of pile threads, but which can be found only in the outer layers, may show the same structure and may have been subjected to the same preliminary or finishing treatment The expression "pile thread" will thus never have to be interpreted in a narrow sense. They can thus contribute to an increase of for example the bending stiffness and the bending strength of said three-dimensional textile products and/or their composites.

To achieve the objects mentioned in the preamble, at least the textile thread which is destined as pile thread for this textile product is subjected to one or more of the following textile treatments : a) the textile thread is enveloped; b) several textile threads are added to the textile thread, c) the textile thread is structured by making use of at least one monofilament and at least one multifilament, d) the textile thread is structured by making use of at least one monofilament and at least one multifilament thread which consists at least partially of thermoplastic fibres, e) each of the textile treatments mentioned in points a - d are performed under such circumstances that the textile thread is kept sufficiently flexible during a first textile treatment such as three-dimensional knitting or three-dimensional weaving and can be stiffened in a subsequent treatment such as thermoforming, melting together or impregnating with a matrix

Other advantages and properties of the invention will become apparent from the following description of a textile thread, i a a pile thread, especially but not exclusively for use in three-dimensional textile products, according to the invention This description is only given by way of example and does not limit the invention The reference numerals relate to the figures annexed hereto all of which showing sections, on a very enlarged scale, of textile threads i a pile threads according to the invention in different embodiments Figure 1 relates to a monofilament having an envelope of natural fibres and/or synthetic fibres

Figure 2 relates to a monofilament having an envelope of polyester fibres with a low melting point and polyester fibres with a high melting point Figure 3 concerns glass yarn filaments bound in acrylic resin

Figure 4 concerns a monofilament twined together with two threads of spun bi-component PET yam.

Figure 5 concerns a continuous glass thread with a multifilament yam assembled and/or slightly twined into a yam, i.a. a pile yam.

Figure 6 concerns a glass thread with a slightly twined monofilament.

The embodiments illustrated by these different figures and selected only by way of example are thus examples of possible textile threads, i.a. pile threads or fibre assemblies comparable therewith which meet the objects set forth in the preamble. The invention will now be described mainly with respect to the manufacture of a three-dimensional textile product, the pile threads of which being stiffened. Fundamentally, the invention relates indeed to producing and applying sufficiently flexible pile threads which can be applied in high densities and which can be stiffened without having to fill up the distance between the layers of the three- dimensional textile product, for example with foam. An advantage of the thus obtained product is of course its good air permeability. One or more monofilaments or multifilament threads having a small number of filaments (2 to 50) can be spun around, intermingled, twisted, braided together, knitted, cabled or assembled by means of other possible techniques by making use of a material which provides at the same time a good adhesion between the different components after which the textile process (three- dimensional knitting, weaving, tufting, sewing, etc.) is completed. In order to prevent shifting with respect to stiffer materials, such as this may occur with monofilaments having an enveloped spun therearound, the core, consisting for example of a PET monofilament, may be roughened or the envelope may be glued to and/or melted together with the monofilament, serving as core yarn. It is also possible to process two or more of these spun around, twined around, knitted

around yarns together once more before proceeding with weaving, knitting, braiding, tufting, etc. to obtain the three-dimensional textile product discussed in the preamble.

The pile thread can thus be hardened or stiffened by hardening the pile material during a finishing treatment after the textile treatment by adding a resin or by melting the envelope having a lower melting point and allowing this envelope to solidify afterwards.

It is also possible to pass one of the used yams, filament yarns or spun yarns before the weaving process first through a bath with a dipping material which provides after drying at about 110°C a still sufficiently flexible pile yarn. Upon a subsequent thermofixing, after a textile processing at a temperature of about 160 - 180°C, the pile thread is harder and stiffer. An example thereof is a treatment of the yarn in a bath of acrylic. It is clear that, besides an acrylic material, numerous other technically equivalent synthetic materials can be considered.

With respect to the figures annexed hereto, the following can thus be said.

In Figure 1 , a monofilament 1 is wound around with an envelope consisting of the same weight of ramie and viscose. The knitted fabric or the textile product obtained according to another technique is subsequently treated with a resin and gives a much larger stiffness than when use is made of a thicker monofilament. In this figure, the synthetic fibres are indicated with reference 2 and the natural fibres with reference 3. The monofilament 1 may consist of PET, PA 6, PA 66, PA 46, PA 12. PVC, PP, PE. PEI, PAI, and technically equivalent materials. The synthetic fibres 2 are fibres to which i.a. PA 6, PA 66, PE, PET, PA 12, PA 46, PP. etc. pertain. Examples of natural fibres 3 include ramie, flax, cotton, jute, sisal and technically equivalent natural fibres. Synthetic fibres, such as viscose may also be taken into consideration.

The pile thread according to Figure 2 consists of a monofilament 4 having an envelope of polyester fibres 5 with a high melting point (about 256°C) whereas the fibres 6 are polyester fibres with a low melting point (about 110°C). After knitting or after another textile treatment, the whole is thermofixed at a temperature of about 200°C and the envelope is melted to the monofilament which forms the core yarn. Also here, a strongly increased stiffness of the three-dimensional textile product is to be expected.

In Figure 3, a multifilament glass yarn 7 is shown which is previously impregnated with an acrylic resin or a technically equivalent resin, in such a manner that an uptake of about 20% in weight of this material is obtained. This thread is dried at a temperature of about 110°C and is thermofixed after knitting at a temperature of about 160 to 180°C. This results in a stiff three-dimensional knitted fabric. The herein described treatment and the obtained filament permit to obtain a sufficiently flexible thread during knitting. This is to due to the fact that, after a drying process at about 110°C, the polyacrylic resin is not completely hardened yet, so that a three-dimensional textile product (three-dimensional knitted fabric) can be obtained with the desired density and pile height. Only after thermofixing at a temperature of about 180°C, the desired stiffness of the three-dimensional material is obtained.

In Figure 4, a monofilament 8, consisting for example of a PET thread of 18 micrometer twined together with two threads of spun bi- component PET yarn 9, is shown. The bi-component threads 9 consist of PET fibres 10 with a high melting point and PET fibres 11 with a lower melting point. The thread shown here is a twined thread consisting of a monofilament PET thread (18 micrometer) twined together with two bi- component PET threads 10 and 11. The applied twist comprises 120 t/rn. The threads obtained in this way are woven into a three-dimensional

woven fabric, the surface threads of which consist for example of 167 dtex PET FTF The monofilament 8 in this assembly assures that a sufficient distance is maintained between the two woven surface fabrics of the three-dimensional textile product After thermofixmg at a temperature of about 200°C, a sufficient stiffness is obtained at a velocity of 20 m/min and a zone length of 20 m, which corresponds to an exposure of 1 mm , to use the obtained woven fabric as a stiff three- dimensional material

Figure 5 shows a continuous glass thread 12 obtained by assembling glass fibres 13 with fibres 14 of another yarn Such a yarn can be tufted on a base layer and after raising, the multifilament yarn which has a lower melting point than the base layer, is heated to melt, whilst the base layer does not melt The result is a stiff tufted material meeting the objectives of the invention In Figure 6 a glass thread 15 is finally shown consisting of a monofilament (20 tpm) having an envelope of glass thread fibres 17 By means of such a glass thread three-dimensional knitted fabrics can be obtained

The fields wherein the different hereinabove described products can be employed can be subdivided as follows a) sports products, such as helmets, protective jackets (for example for hockey players), legguards knee and ankle pads soles for sports shoes, saddles, blankets for horses, sports mat underlays, etc , b) safety products such as inner linings for protective jackets (bullet- or shrapnel-proof) insoles for safety and other shoes (for example boots), bumpers etc c) products for the protection of the environment such as vibration dampers filtration applications, screening of machines and other noise and vibration sources, insulation materials, etc ,

d) building sector : applications such as floor underlays, walls including displaceable roof insulation, wall insulation; e) tools such as light cases which have to be insulated from heat and impact, brake plates, clutches. The invention is not limited to the embodiments described hereinabove and a lot of modifications could be applied thereto, insofar as they fall within the scope of the claims annexed hereto.