Patent GB-1186215-A (GB)
Title: Improvements in Leather-Like Microporous Sheet Material and Method of Making Same.
IPC: D04H1/54
Filed: 1967-05-30
Abstract: 1,186,215. Imitation leather. UNIROYAL Inc. 30 May, 1967 [31 May, 1966], No. 24832/67. Heading B2E. A method of making flexible, permeable sheet material, e.g. a material made in imitation of leather, comprises the steps of providing a flexible permeable base sheet, applying over the base sheet a permeable tie coat of tacky particles bonded to the base sheet, spraying a material comprising a solution of polyurethane elastomer to form tacky fibres, depositing the fibres over the coat to form a permeable body layer, and compacting the resulting assembly by pressure at elevated temperature. In one method of making the material a batt 21, Fig. 1, is fed onto a conveyor 20, sprayed with an adhesive non-fibrous tie coating composition by a device 22 to form discrete particles on the batt and dried in an oven 23. A mixture of tacky polyurethane fibres from a spray device 24 and flock from a spray device 25 is applied to the batt to form a fibrous tie layer, and then a similar mixture is applied to the tie layer from sprays 26 and 27 to form the fibrous body layer. A finishing coat or coats is applied by spray 28 and dried in an oven 29 and/or by heated platens 30 before the assembly is stripped from the conveyor 20 and compacted between a heated embossing roller 32 and a back up member 33 e.g. an inflatable device or resilient pad or roller. If desired the fibrous tie layer sprays and/or one or both of the flock sprays 25, 27 may be omitted, and the non-fibrous tie coat may be applied by a print roller. The sprays may be electrostatic and may be movable longitudinally or transversely of the batt. The base batt may be a non-woven, woven, or knitted fabric or leather and is preferably an air-needlepunched non-woven mass of bonded fibres, e.g. fibres of nylon, polyester, polypropylene, rayon or cotton or mixtures thereof bonded with a natural or synthetic, e.g. polyurethane, latex. The fibres may be crimped, and the batt may be buffed on one or both faces. The non fibrous tie coating may be a latex or solution of polyurethane, neoprene, nitrile rubber, SBR or natural rubber. The fibrous tie layer and fibrous body layer are formed from a sprayed polyurethane elastomer solution, which solution may include a vinyl resin, e.g. p.v.c., and the tie layer solution may also include an aqueous polyurethane latex. The flock may be cellulosic or of nylon, polyester fibre, polypropylene, or rayon, or leather particles or vinyl resin particles, or mixtures thereof. The finishing coat may be a water-soluble dye or a pigmented solution of cellulose nitrate and polyurethane, or of acrylic or vinyl resin, or an acrylic latex. In a second embodiment a batt is knife coated with a frothed latex of polyurethane, SBR, natural or nitrile rubber, neoprene, vinyl or acrylic latex and dried in an oven before a reinforcing non-woven, woven, or knit fabric, e.g. woven cotton, is applied to the latex between hot press rolls. The assembly so formed is then treated as the batt 21. In a further embodiment a batt and a reinforcing fabric are each sprayed with a non-fibrous tie coat, dried, and the coated faces brought together with a sprayed fibrous tie coat between them to form an assembly which is treated as the batt 21.