Patent GB-843041-A (GB)
Title: Fibre webs and method of producing same
IPC: D04H1/74
Filed: 1958-03-06
Abstract: 843,041. Treating fibre webs. NESS, I. S., and LINTS, R. V. March 6, 1958, No. 7308/58. Class 120(3). [Also in Group VIII] To improve the cross-strength of an unbonded, unwoven web of oriented textile fibres, the fibres are re-oriented by increasing the dimension of the web in a direction normal to that in which the fibres are originally oriented, the dimension in that direction being simultaneously decreased. This process aims to increase the average angle between the individual fibres and the longitudinal axis, and may be carried out by engaging the web on "extensible carriers" If desired, the web may be bonded to form a fabric. A web, e.g. a laminate of superposed webs from a carding engine is plied with a carrier sheet to which it is caused to adhere by wetting. The ply is then crossstretched and the carrier removed or allowed to remain: in either case the material is bonded with or without the addition of an unbonded un-oriented web. The water used for wetting the plies may contain a wetting-agent, or a material which acts as a bond when the material is dried, and the bonding with an additional web may take place when the other ply or plies are still wet. Instead of wetting the web and the carrier, suction or pressure may be used to cause them to adhere: pressure may be produced by binding the materials over a roller or by arranging an additional sheet of metal fabric above the web. When the carrier is removed, it may be, re-used, being in the form of an endless belt. The "extensible carrier" may take the form of a sheet of elastomer or rubber or of knitted or "island-bonded" oriented non-woven fabric, or it may take the form of the arrangement of laterally-extensible elements shown in Fig. 7. Each element 146 consists of spring 147 secured to rods 151 at each end of a tubular sheath of rubber &c. The rods each have yokes 153 slidable on rods 145 secured to endless chains 142. As these rotate, camelements 152 on the yokes engage cam-tracks 144 whereby the springs are extended and carry the sheaths with them. Two sets of such elements are arranged one above the other with the web between them, so that upper and lower elements alternate and mesh with one another: the positions of the sprockets by which the chains are carried and driven are adjustable to vary the tension of the chains and also so that the extent to which the elements mesh may decrease from the inlet end to the outlet end of the machine in such a way that the portion of web between any two elements in one set is uniform throughout its passage through the machine. The web is wetted at 121 before passing through the machine, an air-cylinder 130 being provided to vary the pressure between two rolls to control the extent to which the web is wetted. The oriented web may consist of fibres of cotton, wool, jute, ramie, abaca, rayon, nylon or "Dynel" (Registered Trade Mark): as bonding materials the following may be used: certain natural gums, starches and synthetics such as polyvinyl alcohol, chloride, acetate and butyral, carboxymethyl cellulose, urea and melamine formaldehyde. Specifications 674,779, 677,928 744,839 and 745,065 are referred to.