NO882960L - TAPE WITH FUEL BELTS AND TRANSPORT BELTS. - Google Patents

Abstract

The invention seeks to provide a band containing non-woven fabric, for drive and conveyor belts, which band does not build up electric charges. The fibre mixture of the non-woven fabric contains about 1 to 10 % by weight of electrically conductive fibres. <IMAGE>

Description

The present invention relates to a band with non-woven fabric for drive belts and conveyor belts.

Drive belts and conveyor belts are manufactured i.a. using non-woven fabrics that have the lowest possible stretchability and possibly a certain elasticity to prevent an extension of the conveyor belt during use and thereby a necessary post-tensioning.

Hereby, a problem arises from the easily induced electrical charging of the band or belt, for example of the kind known from the working method of a van der Graff generator. Especially for the transport of sensitive, e.g. electronic parts, this effect is extremely undesirable.

It is already known to make non-woven fabrics antistatic, in order to avoid charging of carpets and other artificial fiber-containing materials, it has consequently been proposed to incorporate conductive fibers into them.

In DE-OS 20 16 403, for the prevention of static charging of carpets, it is proposed to use a base fabric as a tufting for carpets and needle filters which has filament yarn or fiber yarn of a fiber mixture with metal fibers or metallized fibers.

DE-PS 19 17 587 also proposes the addition of metal, preferably steel fibres, to a layer of different fiber materials.

In order to prevent static charging of turntables on record players, it has already been proposed in DE-PS 24 57 542 to incorporate metal fibres, especially steel fibres, into a felt with which the platter is coated.

Conductive fabrics of a nonwoven with a metal fiber content for filter purposes are described in "Textile Institute and Industry", 7, 1972, page 199.

Within the state of the art, guide rails are used which are not subject to special requirements in terms of resistance to longitudinal expansion and which are not suitable for conveyor belts.

It has also already been proposed to manufacture such conveyor belts with binders or coating compounds to which conductive substances, mostly soot or metal dust, have been added, to prevent charging. This has the disadvantage that, as a rule, dark conveyor belts are obtained, while for many areas of application, such as within the electronics or food industry, the lightest possible belts are desired. The tapes used up to now have either been cumbersome to produce, or have been subject to disadvantages due to a very quickly worn-down coating. The problem has been exacerbated by the ever-increasing use of synthetic fibres, which are used because of their good properties for conveyor belts which must have a constant length, these show a particular tendency to electrical charging.

The invention is therefore based on the task of equipping belts with non-woven fabric for drive belts or conveyor belts in such a way that charging of the conveyor belts can be avoided.

According to the invention, the task is solved by a tape material which has a nonwoven fabric in which the fiber mixture in the nonwoven fabric has 1 to 10% electrically conductive fibers by weight.

As fiber nonwovens, different nonwovens can be used, for example needle nonwovens, "Wirrfaser" nonwovens, etc.

The fiber mixture in the non-woven fabric may contain synthetic and/or natural and/or regenerated fibres, such as polyester, polyamide, polypropylene, polyacrylic, cotton, coconut, cellular wool fibers etc.

It is particularly preferred when the tape exhibits one or more very strong non-extensible yarns, filaments, weaves or layered fibers of synthetic and/or natural and/or regenerated fibres. Suitable fibers include polyester, polyamide, polypropylene, cellular wool, polyaramid, glass and ceramic fibers or combinations thereof are incorporated.

As electrically conductive fibres, fibers which exhibit at least one metal or elemental carbon can be used.

For example, steel fibers or copper fibers are suitable for this purpose, but metallized, for example copper-plated or silver-plated wires can also be used. Under carbon is understood here conductive carbon modifications, such as graphite needles.

For this purpose, in a preferred embodiment, steel fibers with a titer of 0.8-18 dtex, preferably 3-10 dtex, and a staple length of 20-80 mm have proven advantageous.

It is preferred that the breakdown resistance of the viiess material at 100 V voltage amounts to 10<2> to 10<8>, preferably 10<4> to 10<6> ohms.

Hydrophobic binders can be used, such as nitrile-butadiene-rubber and/or styrene-butadiene-rubber-latex.

A conductive nonwoven material for drive belts and conveyor belts is preferably a mechanically stitched synthetic fiber nonwoven with incorporated conductive fibers and binder, with which the base nonwoven is impregnated. In the production of the nonwoven fabric, which may contain one or more weaves or laid out structures, conductive fibers are added to the nonwoven fabric, then the mechanically attached nonwoven fabric is impregnated with a binder solution and then dried at a temperature of 100°C.

Hereby, the fiber lamination of the fleece material can exhibit synthetic and/or natural and/or regenerated fibres. As synthetic fibres, for example, polyester fibres, polypropylene fibres, or mixtures of these, have proved to be beneficial, particularly because of their high durability, but also because of their favorable price.

Electrically conductive fibers are particularly preferably used which exhibit at least one good conductive and flexible metal, such as copper, iron, aluminum or fibers or elemental carbon which is coated with a conductive metal.

Preferred binders are nitrile-butadiene-rubber and/or styrene-rubber-latex. As a binder, for example, aqueous dispersions of nitrile-butadiene-rubber, styrene-butadiene-rubber latex or binders dissolved in solvents, such as polyurethane, polyvinyl chloride, polyacrylate or mixtures thereof, can be used.

Hereby, the ratio between fiber and binder can preferably amount to 1:2 to 2:1, particularly preferably 1:1.

To improve the surface, the impregnated and dried non-woven fabric can then be sanded on one or both sides, for example with emery paper.

A fleece suitable for the manufacture of drive belts and conveyor belts can have thicknesses of 1-8 mm, preferably 2-5 mm, and have a basis weight of 300-6000, preferably 1000-4000 g/m2.

A conductive nonwoven material According to the invention for drive belts and conveyor belts consists of a preferably synthetic fiber nonwoven which is fixed mechanically, binder and fillers, dyes and vulcanizing agents, whereby the fiber layer contains 1-10% by weight of conductive fibers of steel, graphite, cell wool, or silver-plated or copper-containing fibres.

Further features and advantages of the invention appear from the following description in which a preferred embodiment is described with the help of the drawing where a band according to the invention is shown. The drawing shows: Fig. 1: a partial section of a belt according to the invention seen from above;

and

Fig. 2: the partial section of the band in fig. 1 in cross section.

As shown in fig. 1 is a belt according to the invention formed by means of a fiber nonwoven layer 10, here with 10 weight-# steel fibers with 6 dtex. In the cross section in fig. 2, it appears that the steel fibers are distributed regularly throughout the total thickness of the web.

Example:

For a polyester fabric, respectively — laid out material with a basis weight of approx. 100 g/m<2> of 6 threads 1100 dtex in the longitudinal direction and 3 threads 1100 dtex in the transverse direction, 950 g/m<2> polyester fibers consisting of 2 parts 6.7 dtex and 1 part 17 dtex are stitched on both sides , to which 2 weight # steel fibers of 9 dtex have been added, so that the thickness of the fleece is 6 mm, the basis weight 2000 g/m<2> and the density 0.33 g/cm<5>.

The base fleece is then impregnated with 100 wt-# of nitrile-butadiene-rubber-latex to which 25 wt-# of CaCO3 has been added as a filler and 5 wt-# of vulcanizing agent of sulfur and zinc oxide, it is coagulated in an infrared shaft, washed out, the water is removed, then it is dried at 150°C and vulcanized. It is then sanded using binder-fixed non-woven fabrics on both sides with emery paper, coarseness 120, so that a regular, smooth surface and a thickness of 5.5 mm is created.

The product has a surface resistance of 1 x IO<5>ohm at 100 V applied voltage.

Claims (5)

1. Belts with non-woven material for drive belts and conveyor belts, characterized in that the fiber mixture in the non-woven material has 1 to 10% electrically conductive fibers by weight. 2. Tape according to claim 1, characterized in that the fiber mixture exhibits synthetic and/or natural and/or regenerated fibers. 3. Tape according to one of the preceding claims, characterized in that the assault resistance at 100 V voltage amounts to IO <2> to 10 <8> , preferably IO<4> to IO <6> ohms. 4. Tape according to one of the preceding claims, characterized in that the conductive fibers exhibit at least one metal or elemental carbon. 5 . Ribbon according to one of the preceding claims, characterized in that it exhibits one or more strong, non-stretchable yarns, filaments, weaves or layered fibers of synthetic and/or natural and/or regenerated fibres.