GB782952A - Improvements in leather substitutes - Google Patents

Abstract

782,952. Agglutinated fibrous sheet materials. DU PONT DE NEMOURS & CO., E. I. Aug. 12, 1955, No. 23350/55. Class 140. A leather-like product comprises, by weight, 40 to 85 per cent of matted oriented fibres of a synthetic linear condensation polymer and, distributed therethrough, 60 to 15 per cent of a polymeric binder, chemically dissimilar to the said linear condensation, polymer, incompatible therewith and melting below the softening temperature thereof, the said product containing a volume per cent of interconnecting void space distributed therethrough at least equal to 3000 (weight per cent fibre)<SP>-1</SP>-30 and not greater than 70 per cent. The product may be prepared by mixing the fibres with the binder and then partially consolidating the mixture under controlled conditions of temperature and pressure. Mixing may be carried out by impregnating a porous non-woven mat, web, or felt of the fibres with a solution or dispersion of the binder or, where fibrous or particulate forms of the binder are used, by mixing such as is achieved in conventional carding procedures. The mat, prior to impregnation with the binder should have a bulk density of less than 0.5 g/cc. Mats may be formed by paper-making techniques, carding or deposition from an air stream. Specified polymers for use as the fibre component are dibasic acid/diamine or amino acid polyamides, the dibasic acid/diol or hydroxy acid polyesters or the intermixed polyester/polyamide products or mixtures thereof; such as polytetramethylenesebacamide, polyethyleneterephthalamide, poly-D-, or L-, or DL-alanine, poly-D, or L-, or DL-leucine, and polyepsilon-amino-caproic acid, polydodecamethylene adipate, polyethylene sebacate, polyhexamethylene oxalate, poly-D-, or L-, or DL-lactic acid, poly-D- or L-, or DL- mandelic acid and poly-epsilon-hydroxy-caproic acid. Structural fibres ranging in length from 0.01 inch to 8 inches may be used. Specified polymers for use as the binder are cellulose acetate, cyanoethyl cellulose, polyethylene, polypropylene, polyisobutylene, polybutene-2, polyisoprene, vinyl chloride, 2-3-dichlorobutadiene, vinyl acetate, butadiene (styrene, tetrafluoroethylene/ethylene, vinyl chloride/vinyl acetate and vinylidene polymers and copolymers including both the monoene and diene types. The fibre-binder ratio may vary, on a weight basis, from 40/60 to 85/15. In an example 2 mats of polyhexamethyleneadipamide fibres are impregnated with a dispersion of polyvinyl chloride/di-2-ethylhexyl phthalate in a tetrahydrofuran/dimethyl formamide solvent mixture, dried, plied together and then pressed for 10 minutes at 160‹ C.