Patent GB-989433-A (GB)
Title: Improvements in or relating to flexible sheet material
Inventor: GOY RONALD STANSFIELD
IPC: D06N3/00
Filed: 1961-03-02
Abstract: 989, 433. Fibrous fabrics. DUNLOP RUBBER CO. Ltd. Feb. 20, 1962 [March 2, 1961], No. 7578/61. Heading D1R. A leather like sheet material comprises a consolidated mat of interpenetrated crimped continuous filaments bonded together with a resinous or elastomeric bonding agent, the interpenetration of the filaments being in the nature of an intermingling at random in three dimensions produced by laying the crimped continuous filaments under tension and subsequently releasing the tension. Suitable filaments include those of nylon, polyethylene-terephthalate, polyacrylo-nitrile; polyole - fine and rayon types and natural silk. The bonding material may comprise a thermoplastic resinous or elastomeric binder preferably flexible at room temperature. It may be of a composite nature or there may be a first bonding composition which bonds the fibres simply at their crossing points and a second bonding composition which extends more generally around the fibres. Suitable elastomeric binders include polyurethane rubber, natural rubber, butyl rubber, rubbery styrenebutadiene copolymers, butadiene-acrylonitrile copolymers, polychloroprene rubber &c. Suitable resinous binders include polyolefines such as polyethyline. The consolidation of the mats of filaments is preferably carried out by pressing and heating the mats between platens or rollers or by heating the impregnated mat and passing it between cooled rollers. The weight ratio of fibre to bonding material may vary from 9. 0 to 1 to 0. 8 to 1. Various methods of forming the leather-like material are disclosed as follows:- (1) crimped continuous filaments are collected under tension into layers, the layers are plied together, the tension released so as to cause interpenetration of the filaments of adjacent layers, material affording the bonding agent is applied to the sheet and the sheet is then consolidated. (2) crimped continuous filaments are collected under tension into layers to which material affording the bonding agent is applied, the tension in the filaments is removed and the layers plied together and consolidated. The layers may be heated before being plied together. (3) crimped continuous filaments are collected under tension into layers, the tension on the filaments is relaxed and the separate layers are treated with material affording bonding agent. The layers are then plied together and consolidated. (4) crimped continuous filaments are collected under tension, the tension is relaxed, the layers are then plied together with material affording the bonding agent in sheet or mesh form between them and the material consolidated by heat and pressure (5) crimped continuous filaments are collected under tension into layers in one or more of which the bonding material is incorporated in thread form, the layers are then released from tension plied together and consolidated. Additional bonding material may be applied which may be the same or different from the previous bonding material. (6) crimped continuous filaments are collected under tension preferable in parallel form, the tension is relaxed, material affording the bonding agent is applied to the mat and the mat consolidated. (7) crimped continuous filaments, preferably in parallel form are continuously collected under tension, material affording the bonding agent is applied, the tension removed, additional bonding material applied if desired and the impregnated mat consolidated. The mats may be formed by winding the filaments under tension on to a rectangular frame and then removing the mat so formed. Alternately an assembly of filaments may be drawn under tension from a creel and allowed to relax under controlled conditions, such as by passing them between two pairs of rollers, the second pair rotating at a slower speed than the first. In the apparatus shown pre-tensioned crimped continuous filaments are drawn under tension from beam 1 retarded by a brake 2, through a comb 3 by rollers 4, 5. After rollers 4, 5 the assembly is advanced more slowly and is allowed to relax between moving endless bands 6, 7. The belt 6 carries the assembly beneath binder nozzles 8 and 9 and through a drying and heating tunnel 10. Under the nozzles 8, 9 is located a hopper 11 and under heater 10 is a hopper 12. Suction is applied to these two hoppers to effect the removal of binder solvent or dispersion medium and hot air is admitted to the tunnel 10 through inlets 13, 14. After leaving tunnel 10, the material passes through a pair of cooled pressure rollers 15, 16 which consolidate the sheet which is then wound up on roll 17.