PT87899B - WITHOUT STRETCH BELT FOR DRIVE BELT AND TRANSPORT BELT - 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

L0HMANN GmbH & Co. KG., German, industrial, headquartered in Irlichex Str. 55, 5450 Neuwied 12, Federal Republic of Germany, intends to obtain in Portugel, for: BELT WITH UNDWIDED FABRIC FOR DRIVING AND TRANSPORTING BELTS.

Mod. 71 - 10 000 «X - 4-87 The present invention relates to a nonwoven belt for drive belts and belt conveyors.

The drive belts and for belt conveyors are inter alia produced using nonwoven fabrics that have a small extensibility and optionally a certain elasticity in order to avoid the elongation of the belt conveyor during its use and the consequent retightening.

There is a problem with static charges easily appearing on the belt, for example, similarly to what is known to happen in the case of the operation of the generators of ven der Graff. This effect is particularly undesirable for the transport of sensitive parts, for example, parts electronic.

It is already known how to apply an antistatic finish to nonwoven fabrics and it has been proposed to incorporate conductive fibers in carpets that include materials that

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Mod. 71 · 10,000 βχ - 4-07 contain synthetic fibers to prevent the accumulation of electrical charges.

The specification of the German Patent Application published for public inspection N ² DE-OS proposes, to avoid the accumulation of electrical charges in carpets, the use of a basic fabric for tufted carpets and textile fabrics obtained with needles that have filaments or fiber yarns from a mixture of fibers with metallic fibers or metallic fibers.

German Patent No. ² 19 17 587 relates to the addition of metallic fibers, preferably steel fibers to a laminate formed from different fibrous materials.

In order to avoid the formation of static charges on rotating disc plates, in German Patent N ² 24 57 542, it was proposed to incorporate metal fibers, particularly steel fibers in the felt that covers the said rotating plates.

In the Textile Institute and Industry, Volume 7, 1972, page 100, conductive fabrics made from a fleece with a certain content of metal fibers are described for filtration purposes.

The prior art uses fleece which is not subject to any special requirements with respect to resistance to linear stretching and which are not suitable for belt conveyors.

In order to avoid the accumulation of loads, it has already been proposed to produce these belt conveyors with binder or coating materials to which conductive substances have been added, usually carbon black or metal powder. A drawback of this solution is the fact that dark colored conveyor belts are always obtained, en2

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Mod. 71 - 10 000 βχ -4-87 and for many uses such as the electronics industry and the food industries, light colored belts are preferred. Known belts are either too complicated to manufacture or inconvenient because they wear out very quickly. The problem has become more difficult with the increase in the use of suitable synthetic fibers as a result of its favorable characteristics for use on conveyor belts of constant length that tend to increase in electrical charge.

The problem that the present invention aims to solve is to provide belts finished with a nonwoven fabric for conveyor and drive belts in such a way that they can be prevented from being electrically charged.

According to the present invention, this problem is solved by using a belt material that has a fleece in which the fiber blend of the nonwoven fabric has approximately 1 to 10% electrically conductive fibers.

Nonwoven fabrics can be made up of most of the various fleece, for example, dotted fleece, interwoven fiber fleece, etc.

The fiber blend of the nonwoven fabric may have synthetic and / or natural and / or semi-synthetic fibers, such as for example polyester, polyamide, polypropylene, polyacrylics, cotton, coconut and wool fiber or the like.

It is particularly advantageous that the belt has one or more strands of high mechanical resistance and small length, filaments, fabrics or fabrics braided from synthetic and / or natural and / or semi-synthetic fibers. Suitable fibers are, among others, fibers of polyester, polyamide, polypropylene, wool, polyamide, vi- 3 59,961

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Mod. 71 - 10 000 βχ - 4-07 dro and ceramics or their combinations.

The electrically conductive fibers used can have at least one elemental carbon or metal. For example, it is appropriate to use steel or copper fibers for this purpose but it is also possible to use metallized fibers, for example, fibers coated with copper or silver. Carbon is considered to consist of conductive allotropic forms, such as graphite filaments.

According to a preferred embodiment, steel fibers with a titer of 0.8 - 18 and preferably 3-10 dtex and with a fiber length of 20 - 80 mm are advantageous. It is advantageous that the perfective strength of the nonwoven fabric at 100 V is 10 to 10 and / or preferably 10 ⁴ at 10 ohm.

It is possible to use hydrophobic binders such as nitrile / butadiene rubber and / or rubber / butadiene latex.

A nonwoven conductive fabric for drive belts and conveyors comprises a mechanically dotted fleece of synthetic fibers with incorporated conductive fibers and a binder with which the base fleece is impregnated. During the production of non-woven fabric that can contain one or more interlaced fabrics or fabrics, conductive fibers are mixed with the fiber fleece, the mechanically hardened fleece is then impregnated with a binder solution and then dried at a temperature of 100 ° C .

The fiber blend of the nonwoven fabric may contain synthetic and / or natural and / or semi-synthetic fibers. Suitable synthetic fibers are, for example, polyester fibers, polypropylene fibers or mixtures thereof, particularly due to their great stability

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-1. JUL.1988 ίβ -> - »000 01- U Ί and favorable price.

Particularly preferred electrically conductive fibers are those that have at least one easily conductive and flexible metal such as copper, iron, aluminum or fibers covered with a conductive metal or elemental carbon.

Preferred binders are nitrile / butadiene rubber and / or styrene / butadiene rubber latex. As a binder, for example, it is possible to use dispersions of nitrile / butadiene rubber, styrene / butadiene rubber latex or binders dissolved in a solvent, such as polyurethane, polyvinyl chloride, polyacrylate or mixtures thereof. The ratio of fiber to binder is preferably between 1: 2 and 2: 1 and, in a particularly preferred manner, is equal to 1: 1 parts by weight.

The impregnated and dried nonwoven fabric can then be subjected to abrasion for example with emery paper on one side or on both sides to improve the surface.

A fleece suitable for producing drive belts and conveyors can be 1 to 8 mm and preferably 2-5 mm thick and have a weight per unit area between 300 and 6 000, preferably 1000 to 4 000 g / m ² .

A conductive nonwoven fabric according to the present invention for drive belts and conveyors comprises a preferably synthetic fiber fleece which has been mechanically strengthened, binders and fillers, dyes and vulcanizing agents, wherein the fiber mixture contains 1 to 10% by weight of conductive fibers made of steel, graphite, wool or fibers coated with silver or containing copper.

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Other features and advantages of the present invention can be seen in the following description of a preferred embodiment related to the drawings, in which Figure 1 represents a part of the belt according to the invention in plan view; and Figure 2 represents a sectional view of the part of the belt of Figure 1.

As shown in Figure 1, a belt according to the present invention is formed by a layer of nonwoven fabric (10) which, in this case, has 10% by weight of 6 dtex steel fibers. In the straight section represented in Figure 2, the steel fibers are evenly distributed over the entire thickness of the fleece.

Example

With a polyester fabric or pleated fabric with a weight per unit area equal to approximately 100 g / m of 6 fibers of 1100 dtex in the longitudinal direction and 3 fibers of 1100 dtex in the transverse direction are stitched on each side of fibers of 950 g / m polyester comprising two parts of 6.7 dtex and a part of 17 dtex, to which 2% by weight of 9 dtex steel fibers are mixed, so that the thickness of the fleece is equal to 2000 g / The density is 0.33 g / cm.

The base fleece is subsequently impregnated with 100% by weight of nitrile / butadiene rubber latex to which 25% by weight of CaCO4 was added as a filler and 5% by weight of vulcanizing agents formed from sulfur and oxide of zinc, then subjected to coagulation in an infrared oven, washing and draining and then drying and vulcanizing at 150 ° C. The nonwoven fabric strengthened with ligand is then subjected to

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Mod. 71 - 10 000 ax - 4-87 abrasion on both sides with emery paper with a grain size equal to 120 which gives a uniform smooth surface and a thickness equal to 5.5 mm. The product has a surface resistance of 1 x 10 ohm to the applied voltage of 100 V.

The first application for the invention described above was filed in the Federal Republic of Germany on 22 July 1987 under ο N2. P 37 24 328.4.

Claims (4)

13 - Belt with nonwoven fabric for drive and transport belts, characterized by the fact that the fiber mixture of the nonwoven fabric contains approximately 1 to 10% by weight of electrically conductive fibers. 23. The belt according to claim 1, characterized in that the fiber mixture contains synthetic and / or natural and / or semi-synthetic fibers. 3. ^A belt according to any one of the preceding claims, characterized in that the surface resistance at 100 V is 10 to 10, preferably 10 ^ to 10 ^ ohm. 4- Belt according to any of the preceding claims, characterized in that the conductive fibers have at least one elemental carbon or metal. 5 - belt according to any preceding claim, characterized by having one or more wires of high mechanical strength and small extent, filaments, woven or pleated fabric formed from synthetic and / or natural and / or semissintéti35 - 7 59,961 Ref: LOH 14/87 PE 1 cas. Lisbon, -1.JUL.1S88 Mod. 71 - 10,000 βχ - 4-β7 - 8 1/1