Specialized cloth is required for different advanced technical applications such as filtration. Such cloth must sometimes be completely closed or substantially completely closed. Situations can however also be envis- aged in the domestic or recreational sphere where strong and fully or substantially fully closed cloth could find a use, for instance as rainwear, bags, suitcases, sun protection, umbrellas and so on.

For this type of application foils are therefore often used which are manufactured from plastic and the like. However, foils frequently have insufficient strength and can tear easily. Use is also made of induc- ing shrinkage in a fabric, whereby the openings therein become smaller. This does not however always produce the desired result. A fully closed cloth is never achieved.

It is therefore the object of the present invention to provide a new type of cloth which, if desired, can be made completely closed or substantially completely closed and therein still have sufficiently great strength.

This is achieved according to the invention by cloth which consists at least partially of fibres or yarns which are composed of at least two or more components, wherein at least one of the components is a strength- providing component and the other component(s) is (are) a density-causing component(s).

Such a cloth preferably consists at least partially of fibres or yarns which are composed of at least two components from the same raw material but with different melting points, wherein the cloth has undergone a thermal treatment under pressure. The component with the high melting point remains intact under the treatment at increased temperature and pressure and provides the cloth

with strength, while the low-melting component flows out, thus wholly or partially causing density.

The cloth can be a fabric, knit, tricot, non-woven or combination thereof. Due to the thermal treatment under pressure the fibre or yarn component with the low melting point will melt and run into the openings between the warp and weft threads or between the loops of a knit or tricot or between the fibre fragments of a non-woven and thereby wholly or partially close them. However, because the fibres or yarns also have a high-melting component to which nothing happens during the thermal treatment under pressure, the whole cloth still retains the strength of a fabric, knit, tricot or non-woven, this strength being co-determined by the raw material from which the fibres or yarns are manufactured. In addition, the application of a coating or impregnation of the cloth now becomes unnecessary.

The fibres or yarns according to the invention can consist in any random manner of two or more components with a different melting point. Particularly recommended are fibres consisting of a core of high-melting (or normally-melting) material and a coating of low-melting material. Alternatively, fibres can be used consisting of a mixture of two or more types of fibrils, of which the one type consists of a low-melting material and the other of a high-melting or normally-melting material. Both the high-melting (or normally-melting) materials and the low- melting materials preferably consist of the same raw material, more preferably of polyester.

In addition, half the fibres can also consist of the high-melting (or normally-melting) material and the rest of the low-melting material. Yarns consisting of a plu- rality of fibres can be structured from one or more fibres of high-melting material and one or more fibres of low-melting material. The fibres can for instance have a round cross-section, although other cross-sections, such as for instance a trilobal shape, are also possible.

Such fibres and yarns consisting of a plurality of components are known in this technical field under the name "bicomponent fibres or yarns" or "hybrid fibres or

yarns". They can occur in combinations of natural and (semi-)synthetic yarns or fibres, both as monofilaments of a thickness of between for instance 0.1 mm and 2 mm or between 7.5 dtex (0.027 mm) and 45 dtex (0.064 mm).

According to the invention hybrid fibres or yarns of the same raw material are preferably used, for instance polyester.

In an alternative embodiment a so-called Partially Oriented Yarn (POY) can be used instead of at least a part of the low-melting component.

The present invention is particularly suitable for use as sailcloth. Sails, which can be exposed to high wind forces, must especially be strong. For some applica- tions sailcloth must moreover be air-tight. For large sails however, material is recommended which is still partially air-permeable. Sailcloth manufactured from the cloth according to the present invention has in any case the strength of a fabric and, by varying the density of the low-melting component, the cloth can be made wholly or partially air-tight. Sailcloth is preferably manufac- tured from two types of polyester with different melting points. The advantage of using a low-melting (for in- stance at about 1700C) polyester on the one hand and a normally-melting (for instance at about 2550C) polyester on the other is that the fibre in the finished product has sufficient strength for the application in sailcloth.

Such a suitable strength could not be achieved with the use of a combination of for instance low-melting polyes- ter and high-melting polypropylene or polyethylene.

The fabric according to the invention has the fur- ther advantage that, due to the melting of the low-melt- ing part, the stretch, particularly in the Bias (45° direction) is very greatly decreased because the inter- sections of warp and weft are fused. This is desirable for determined applications.

In addition, the cloth according to the present invention is particularly suitable for use in conveyor belts or running belts. The advantage of use in running belts, for instance running belts in training equipment, is that the cloth can be much thinner than the rubber

belts used heretofore. This has the advantage that the heat generated in the cloth by the movement can be dis- charged much more easily. Such belts can thereby be used longer and more intensively.

The cloth according to the present invention is further suitable as parachute material and as material for use in ultra-light aircraft such as hang-gliders, but also normal gliders, in air balloons and so on.

Because the cloth can be made completely closed it is also suitable for use in waterproof clothing, such as raincoats, ski clothing or windcheaters as well as for shower curtains, tarpaulins, rucksacks, suitcases, travel bags, umbrellas and so on.

Cloth according to the invention can also be used in sun-protection products such as sunblinds, roller blinds, Venetian blinds, pleated curtains and in airbags.

A cloth which is not completely closed is particu- larly suitable as filter for ultrafiltration or reverse osmosis.

The cloth according to the present invention can be obtained by providing a fabric, knit, tricot or non-woven of fibres or yarns which are composed of at least two components with different melting points and subjecting the cloth to a thermal treatment under pressure. The thermal treatment under pressure is preferably a calen- dering treatment. The calendering preferably takes place at a pressure of 10 to 60 tons, preferably 30 to 50 tons and a temperature of 100 to 500 cm, preferably 150 to 2500C, more preferably at about 1800C. The pressure and temperature depend of course on the yarn or fibre materi- al used. And the temperature in particular must be chosen such that only the low-melting component melts suffi- ciently to enable good flow, but the high-melting compo- nent substantially does not melt, or is at least left intact such that a desired strength is retained.

The table below gives a number of examples of appli- cat ions. Applications Threads per cm Thickness (dtex) (warp/weft) (warp/weft) Conveyor belt min. 7/7 2200/2200 cloth max. 15/15 280/280 Sailcloth min. 14/14 1100/1100 max. 52/52 167/167 Filter cloth min. 36/36 100/100 max. 80/80 50/50 Suitcase cloth min. 6/6 1002/1002 max. 13/13 501/501 Sunblind cloth min. 23/23 195/195 max. 45/45 76/76 The present invention is further elucidated with reference to the examples below, which are only given by way of illustration.

EXAMPLES EXAMPLE 1 Manufacture of a fully closed cloth A fabric is manufactured from Polyester hybrid HT with a yarn number of 280 dtex and 48 fibrils with 38 warp threads per cm and 22 weft threads per cm. The fabric is then carried at a cycle speed of 18 m/min through a calendering device in which it is calendered at a pressure of 40 tons and a temperature of 2000C.

The thus obtained cloth was found to be completely closed.

EXAMPLE 2 Manufacture of a substantially closed fabric A fabric is manufactured from Polyester HT with a yarn number of 280 dtex and 48 fibrils with 43 warp threads per cm and 15 weft threads. The fabric is then carried at a cycle speed of 15 m/min through a calender- ing device in which it is calendered at a pressure of 30 tons and a temperature of 1800C.

The obtained cloth was still found to be 9% perme- able.