DE102012103844A1 - Membrane comprises elastomeric layers, and embedded fabric layer formed between elastomer layers - Google Patents

Abstract

A membrane comprises elastomeric layers, and embedded fabric layer formed between elastomer layers. The elastomer layer is obtained by connecting warp and weft threads by half-spinning method, and joining warp and weft threads. The fineness related strength of warp yarn is more than 90% in the warp direction.

Description

The invention relates to a molding membrane comprising at least two elastomer layers and at least one embedded between these elastomer layers fabric layer, wherein the fabric is a leno fabric by the half-turning method with warp and weft threads whose mesh size is such that the elastomer layers are connected by the mesh of the fabric ,

Formed membranes are sealing and flexibly movable walls that separate two spaces, in which there are usually different media or two different pressure conditions prevail. Form membranes with elastomer and fabric layers are z. B. used in the automotive industry in fuel management and in the field of exhaust gas recirculation, air conditioning and servo pumps. But they are also used in gas regulators, gas meters, pressure conversion valves and in hot water pumps as well as in medical infusion pumps and in the aerospace industry.

In the DE-OS 2 063 509 Form membranes are described, which should have a high strength and in which delamination of the material layers should be reliably prevented. As a fabric layer, the shaped membranes have a leno or half-leno fabric whose recesses (mesh width) are dimensioned such that the embedding elastomer layers are connected to one another through the recesses.

However, it has been found that molded membranes with conventional leno fabric do not always meet the desired requirements for suitability for higher pressure loads while maintaining good dimensional stability.

The invention is therefore based on the object to provide a molding membrane is available, which has an improved bursting strength with good formability and dimensional stability.

This object is achieved in that the leno weave has carrier warp threads and binding warp threads and the strength utilization of the leno weave in the warp direction amounts to at least 90% of the fineness-related strength of the carrier warp threads used.

A leno cloth with carrier warp yarns and binder warp yarns is characterized in that weft yarns and carrier warp yarns are almost straight in the fabric while the binder warp yarn is wound around the carrier warp and weft yarns with a warp tension different from the carrier warp yarn. This form of tissue is also called Gedrebe and it is sold, for example under the name EasyLeno ^® 2T by the company Lindauer DORNIER GmbH, Germany. It can be produced by this method tissue from very fine yarns with high yarn density. The warp tension should be selected in the manufacture of the fabric so that the strength utilization of the yarn in the warp direction is at least 90% of the fineness-related strength of the carrier warp yarns used. In conventional flat fabrics, the strength utilization is about 80 to 85% of the fineness of the warp threads.

Due to the special design of the leno fabric with almost straight-line orientation of the carrier warp yarns, it is possible to reduce the yarn density at high bursting strength and thus continue to ensure a good connection of the elastomer layers. Solvent-containing adhesive layers can therefore be dispensed with.

The molding membrane according to the invention with the special leno fabric can also very well and with high dimensional stability z. B. be formed in the deep-drawing process, since the elongation of the fabric takes place mainly on the fabric construction and not on the elongation of the thread material.

The molding membrane according to the invention also has the advantage that threads of highly crystalline polymer chains, which have a low material elongation, can be used for the fabric layer of the molding membrane and can be shaped well.

The fabric may contain as filaments both fiber and filament yarns of all native and synthetic, metallic and ceramic raw materials. It may be z. B. yarns of cotton, viscose, polyamide, polyester, aramid, glass, carbon, steel basalt, etc. act. It is possible that different materials are used within a fabric.

According to a preferred development of the invention, the fabric has threads of polyamide, polyester and / or aramid. Molded membranes with such fabrics have low strength (thickness) at high strength and can be produced inexpensively.

For thin as possible and fast responding membranes with sufficient strength, it has proven to be advantageous if the Trägerkett- and weft threads have a fineness of less than 1880 dtex. If the fabric is made of polyester threads, the fineness should be between 33 and 1100 dtex. Corresponding values for aramid are 220 to 1670 dtex for the filament yarn and 100 to 500 dtex for the staple fiber yarn. However, particularly preferred is the use of polyamide yarn with a fineness of 33 to 940 dtex, preferably 33 to 470 dtex.

According to a further advantageous development of the invention, the carrier warp threads and the weft threads differ in their extensibility by not more than 15%. Since a molding membrane is usually a round structure, which is also round shaped, z. B. is deep drawn, the threads in the warp and weft direction should have the same force-strain ratios, so it does not come to irregularities and possible vulnerabilities in the membrane. A fabric with similar extensibility in the warp and weft directions is a symmetrical fabric with z. B. similar fineness of the carrier warp threads and the weft threads.

The present in the molding membrane elastomer layers according to the invention can be applied to different rubbers such. As acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (HNBR) or ethylene-propylene diene rubber (EPDM) are based, with preference NBR or HNBR are used for improved oil resistance.

The molding membranes can be produced by conventional processes, the preparation comprising the molding process. The shaping can be done by embossing. However, it has proven to be particularly advantageous if the molding membrane is a deep-drawn membrane, since during deep drawing the use of the special fabric has a very positive effect on a uniform membrane thickness.

In the following the invention will be explained in more detail with reference to an advantageous embodiment.

A molding membrane was made with the following fabric: Trägerkettfaden: Polyamide yarn PA 6.6, dtex 110 Weft: Polyamide yarn PA 6.6, dtex 235 binder warp yarn: Polyamide yarn PA 6.6, dtex 110

The carrier warp yarn and the binder warp yarn have different elasticity. The carrier warp thread is more aligned than the binding warp thread and thus has a higher design strain. Thus, the strength utilization in the warp direction increases by 15 to 25% and is at least 90% of the fineness-related strength of the carrier warp yarns used.

The fabric was calendered on both sides with an NBR blend and then deep-drawn into the shape of a membrane for a passenger car fuel pump with the thickness of the membrane at 0.28 mm.

The membrane was evenly deep draw and compared to a membrane with a conventional flat fabric, the Trägerkett- and the weft yarn density could be reduced with the same bursting strength from 18 to 12 per cm. This allowed a good penetration of the fabric with the elastomer and thus a particularly good connection.

If one chooses for the carrier warp threads and the weft threads the same fineness of z. B. 235 dtex and wrapped with a binder thread of a fineness of z. B. 78 dtex, it is possible to save even with the same strength utilization even up to 35% fabric material.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2063509 [0003]

Claims (7)

A molding membrane comprising at least two elastomeric layers and at least one fabric layer embedded between said elastomeric layers, said fabric being a leno weave by warp and weft yarns having a mesh size dimensioned to interconnect said elastomeric layers through said meshes of said fabric, characterized in that the leno weave comprises carrier warp yarns and binder warp yarns and the strength utilization of the leno weave in the warp direction is at least 90% of the fineness-related strength of the carrier warp yarns used. Molding membrane according to claim 1, characterized in that the fabric has threads of polyamide, polyester and / or aramid. Molding membrane according to claim 1 or 2, characterized in that the carrier warp threads and the weft threads have a fineness of less than 1880 dtex. Molding membrane according to at least one of the preceding claims, characterized in that the carrier warp threads and the weft threads are polyamide yarns with a fineness of 33 to 940 dtex, preferably 33 to 470 dtex. Molding membrane according to at least one of the preceding claims, characterized in that the carrier warp threads and the weft threads differ in their extensibility by not more than 15%. Molding membrane according to at least one of the preceding claims, characterized in that the at least two elastomer layers based on acrylonitrile-butadiene rubber (NBR) or hydrogenated acrylonitrile-butadiene rubber (HNBR). Molding membrane according to at least one of the preceding claims, characterized in that it is a deep-drawn molding membrane.