Patent GB-869214-A (GB)
Title: A method of making porous webs formed of elastomeric filaments bonded together
IPC: B29C48/05
Filed: 1959-03-10
Abstract: 869,214. Agglutinated fibrous sheet materials; laminates. AMERICAN VISCOSE CORPORATION. March 10, 1959 [April 29, 1958], No. 8275/59. Class 140. A process for producing a porous web formed of elastomeric filaments bonded together in an irregular manner comprising forming a multiplicity of elastomeric filaments, arranging said filaments while still in a tacky condition into two substantially straight line groups so that the line groups extend at substantially rightangles to one another, moving a surface horizontally beneath said groups of filaments in such manner that one of the groups of filaments will fall on to said surface and form lines extending generally in the direction of movement of the surface, moving the other group of filaments back and forth across the moving surface so as to form lines extending generally cross-wise of the surface and moving each group of filaments with an irregular motion generally lengthwise of the group so as to prevent the filaments from falling on to the surface in straight lines. Specified elastomers are rubber latex, neoprene, halogenated rubber, butadiene-acrylonitrile copolymers, butadienestyrene copolymers, isoprene-isobutylene copolymers and organic polysulphides. The elastomer may be in the form of an organisol or plastisol. Abrasive particles may be incorporated in the filaments. Hollow filaments may be produced by incorporating gas-forming agents. As shown (Fig. 1), the elastomeric composition is contained in two tanks 10 and 11, that in tank 10 being forced through orifices 13 in heater 12 to form filaments 15 and that in tank 11 being forced through orifices 22 in header 21 to form filaments 24. Filaments 15 pass through acid bath 14 and out over rollers 16 and 17, following thence in a tacky condition on to continuous belt 18. Filaments 24 pass through acid bath 23 and out over rollers 25 and 26, falling thence on to belt 18. Roller 26 is mounted on slidable racks 30 and 31 driven alternately back and forth by pinions 32 and 33 to cause roller 26 carrying filaments 24 to move back and forth across the surface of belt 18. In order to lay filaments 15 in an irregular configuration, shaft 39 is provided at one end with a follower 40 in engagement with the irregular surface of continuously rotating cam 41 which causes roller 17 to move back and forth in an irregular motion whereby filaments 15 are deposited on belt 18 in an irregular pattern (Fig. 2). In order to lay filaments 24 in an irregular configuration cross-member 29 is attached to pivotally mounted lever 36, whose other end is provided with follower roller 37 in engagement with the irregular surface of continuously rotating cam 38 whereby roller 26 is caused to move back and forth in an irregular manner in the direction of movement of belt 18 and filaments 24 are deposited on the belt in an irregular pattern (Fig. 3). In order further to enhance the random arrangement of the filaments, belt 18 is caused to vibrate in a direction transverse of its feeding direction by magnetic vibrators 43 and 44 connected to the shafts supporting rollers 19 and 20. Fig. 4 shows the general configuration of the web produced by the overlapping of the two sets of irregularly deposited filaments. The web is carried through a curing or vulcanizing chamber 46 after which it is stripped from the belt 18 by passage over roller 47. There may be introduced between the layers of filaments, while these are in a tacky condition, preformed fibres or discrete particles of a non- adhesive non-elastomeric material. Relatively thick bodies may be produced by laminating. Thus the unvulcanized web may be stripped from the conveyer belt and folded upon itself or cut to a desired size and a plurality of such cut layers assembled, and other materials may be introduced between the assembled layers. Specification 794,725 is referred to.