DE9421096U1 - Composite material - Google Patents

Description

Description:

The invention relates to a sheet-like or tubular composite material made up of several layers, one of which is formed by a wire mesh or fabric. At least one surface of this wire mesh or fabric has a nonwoven fabric made of textile fibers or threads.

In particular, wire mesh as an essential component of composite materials are used - in flat or tubular form - in filter and separation technology for liquids and dust, in electrostatic and micro filters, as vandalism protection for textile covers and upholstery of seats in public transport, as soundproofing mats in air silencers, cooling towers and engine compartments, in container and equipment construction as HF shielding of cable harnesses and for sealing tasks in the cable industry, medical technology, sound insulation, automotive and electrical industries. They are commercially available and the brochures list the applications listed (e.g. Max Rhodius GmbH, Weissenburg, Germany: brochure "Maschen in Präzision", freely available on the day of filing).

In the following, "wire knits" are understood to mean flat or tubular, single or multi-threaded fabrics in knitted and woven form, whose wires, individually, parallel to one another or twisted together to form strands, are made of different metals, such as stainless steel, copper, aluminum, zinc or metal alloys, and have round, oval or angular cross-sections. The diameter of the threads is usually 0.05 to 0.60 mm. The width of the fabrics can be 10 mm to 6000 mm. In knitted fabrics, the smallest clear width of the web mesh is 0.5 mm x 0.5 mm. Diagonal and arrow waves of various types can be produced. In woven fabrics, the number of wires in the warp and/or weft direction is 3 to 100/cm.

The assembly of these wire meshes defined in this way into laminates according to the above-mentioned products usually takes place at the customer's premises, with fabrics being used as textiles in particular. The connection is made by sewing threads through the meshes. Nonwovens have also been laminated onto the mesh in the same way. The applicant is therefore aware of composites made of copper wire mesh with textiles, which are used as quilts and components of mattresses in order to shield against "earth rays".

It goes without saying that such a connection is very complex to produce and/or has a lack of bond strength.

Particularly in the field of vandal-proof seats, it has been common practice to embed the knit in foam and only then add the textile cover or other padding.

The invention aims to provide a universally usable composite material, including for seats, made of nonwoven fabric and wire mesh or fabric, which does not require any foam embedding while maintaining very good laminate strength, and can also be used in the other areas of application mentioned.

This object is achieved by a sheet-like or tubular composite material according to the preamble of the first claim, which has the characteristics that the nonwoven fabric is needled to one or both sides of the wire mesh 1 in such a way that at least 1/10 of the nonwoven fibers or threads pass through its meshes.

The manufacturing process uses high-energy water jets, which partially weave the fibers or threads of the fleece or fiber web used through the mesh of the knitted fabric 1 or woven fabric.

The resulting composite is so strong that delamination is impossible even under heavy stress, e.g. on vehicle seats. The composite is completely resistant to knife cuts. Furthermore, a single, simple process can cover the entire product range of wire mesh composites for all applications where a laminate with a nonwoven fabric is desirable.

A surprising effect of the composite according to the invention is that it has a fire behavior according to DIN 54 837 E1/1991, which makes it particularly suitable for use as a flame barrier in seats of public transport or as a flame-retardant lining in their body components.

All nonwoven fiber fabrics, including piles, whose fibers have a length of 3 to 80 mm and a titer of 0.1 to 30 dtex can be used as nonwovens for needling. The parameters are limited at the top and bottom by the ability to be sufficiently interwoven with the meshes of the knitted or woven fabric during water jet needling. The formation of the nonwovens or fiber piles before processing into the composite according to the invention can be carried out using all known techniques in a dry or wet manner. Suitable nonwoven and pile weights have been found to be between 15 and 50 g/m ² .

Equipping the wire mesh 1 with nonwovens on both sides is particularly advantageous if the composite material is to be bonded to another layer of material on each side. In this case, the larger surface area of the nonwoven material - compared to the wire mesh - offers a better adhesive base. Such a version is described in Example 1.

A particularly preferred variant of the process in the interest of improving the form fit of the fibers with one another consists in using a fleece or fiber web with thermoplastic binding fiber content and attaching it to the

This is followed by a known heat treatment of the composite, whereby the fibres are thermo-fixed to one another.

In the following, without restricting the inventive concept, exemplary composites, their production, use and properties are given.

Example 1:

Anti-vandalism composite material for seats in public transport

A fiber pile consisting of a mixture of 70% by weight oxidized polyacrylonitrile fibers (2.2 dtex, 60 mm) and 30% by weight fibers made of cross-linked polyphenols (2.2 dtex, 51 mm), with a surface weight of 60 g/m ² , is placed on a wire mesh 1 made of Cr/Ni steel as shown in the figure. The mesh has a wire diameter of 0.5 mm, a mesh size of 7 mm and a mesh length of 5 mm with a surface weight of 800 g/m ² . This structure made of two layers is needled on the pile side in four stages from three nozzles each with high-energy water jets, whereby the pile fibers become intimately intertwined with the mesh. The jet pressure is gradually increased from 40 bar to 140 bar from nozzle to nozzle and from station to station. In the interest of a positive connection between the fiber fabric and the metal mesh, the speed of the conveyor belt carrying the composite is no more than 20 m/min.

After turning the composite thus obtained, a second fiber web of the same composition is placed on its underside and needled to the wire mesh 1 according to the above method.

The resulting composite material can now be incorporated into the seat structure by gluing it to the molded foam on the underside and to the cover material on the top. It meets the flammability class S4 according to DIN 54 837 E1/1991 and the layer adhesion after gluing according to DIN 54 310 of over

125 N/50 mm. It is not possible for the slot to be slit open by fixed knives.

Example 2:

Belt filter for hydraulic oils

For the inflow side, a hydrodynamically formed fiber pile is made of polyester fibers with a length of 5 mm and a titre of 0.2 dtex. The basis weight of the pile is 100 g/m ² .

This pile is laid on a fabric made of twisted, acid-resistant stainless steel wires. The wire strands have a diameter of 0.6 mm. The fabric has a mesh width of 2 mm and a mesh length of 1.2 mm and weighs 600 g/m ² .

The needling is carried out in the same way as in example 1, but in two stations with jet pressure increasing from to 80 bar. The conveyor belt moves at a speed of 30 m/min,

The resulting composite is turned over and a 90 g/m ² fiber pile is placed on the other side of the fabric, which will later become the downstream side. This consists of polyester fibers, 2.2 dtex, 40 mm fiber length. Here, too, the pile side is needled under the same conditions as above.

The resulting 3-layer composite still shows a high dimensional stability at temperatures above 180 ⁰ C, in contrast to unreinforced belt filters made of nonwovens. Tensile strengths of over 2500 N/50 mm according to DIN 53 857 allow high mechanical stress in industrial filtration processes.

Example 3:

Interlining for protective clothing

A fiber web is made from 60% by weight of an oxidized pitch fiber with 3.3 dtex and a cutting length of 60 mm and from 40% by weight of an aramid fiber, 1.7 dtex, 38 mm cutting length. The basis weight is 40 g/m ² .

This fiber pile is placed on a 90 g/m ² copper wire mesh. The wire diameter is 0.09 mm, the mesh size is 2.5 x 2.5 mm and the mesh length is 1.5 mm.

The water jet needling on the pile side takes place in three stations, each with three nozzles, with the jet pressure gradually increasing from 40 to 120 bar. The speed of the conveyor belt is 30 m/min.

The resulting composite is antistatic, flexible and mechanically resilient. Due to the materials used, it is resistant to most chemicals and has a flame resistance index of A according to BS 6249. It can be used as a reinforcing insert under fabrics or knits which are used to make protective clothing against fire and chemical exposure.

Example 4:
Gas filter

A polyester nonwoven fabric weighing 80 g/m ² is needled onto both sides of a metal mesh made of twisted stainless steel wires using water jets. The bonding conditions correspond to those of Example 1. The polyester fibres have a length of 5 mm and a titre of 0.2 dtex. The strand of the wire mesh, which has a surface weight of 600 g/m ² , has a

a diameter of 0.6 mm. The mesh size is 7 mm, the mesh length 5 mm.

The resulting composite is dried at a temperature of 223°C and thermoset due to the softening of the fibers.

The product has a tensile strength of 2500 N/50 mm according to
DIN 53 857. Its surface is smooth and abrasion-resistant. It is therefore particularly suitable as a gas filter for self-cleaning dust extraction systems.

Claims (2)

94PA0015/DE/G 20.02.1995 Applicant: Carl Freudenberg Company, 69469 Weinheim Composite material Claims: 1. Flat or tubular composite material made of a wire mesh (1) or woven fabric, in which at least one of the surfaces of the composite material is formed by a nonwoven fabric made of textile fibers or threads, characterized in that the nonwoven fabric is needled to the wire mesh (1) in such a way that at least 1/10 of the nonwoven fibers or threads are passed through its meshes. 2. Composite material according to claim 1, characterized in that the wire mesh or wire fabric has a nonwoven fabric on both sides.