| 摘要 |
914,713. Coated bonded fibrous material; coated bonded non-woven sheet material. DU PONT DE NEMOURS & CO., E. I. Aug. 16, 1960 [Aug. 24, 1959], No. 28319/60. Class 140. A process for making moisture-permeable sheet material comprises forming a mat of staple fibres, impregnating the mat throughout with a solution of a synthetic polymer in an organic liquid solvent which is a non-solvent for the fibres, and precipitating the polymer and extracting substantially all the organic liquid solvent from the impregnated mat by treating it with an inert liquid which is miscible with the solvent and is a non-solvent for the fibres and for the synthetic polymers. Suitable fibres are polyethylene terephthalate, regenerated cellulose, cellulose acetate, polytetrafluoroethylene, nylon, copolymers of acrylonitrile and vinyl chloride, copolymers of vinyl chloride and vinylidene chloride, polyethylene and polystyrene. The mat may be formed by carding, by deposition on a foraminous carrier from a liquid suspension, or by air deposition. The mat may be needled before treatment with the binder. Suitable binders are polyurea polymers, plasticized polyvinyl chloride, copolymers of vinyl chloride with vinyl acetate or vinylidene chloride, copolymers of butadiene and acrylonitrile, copolymers of butadiene and styrene, and butyl rubber. Specified solvents are dimethyl formamide, dimethyl sulphoxide, tetrahydrofuran, tetramethyl urea, N,N-dimethyl acetamide and acetone. Suitable precipitants are water, glycol monoethyl ether, hydroxyethyl acetate and polyols, e.g. glycerol and ethylene glycol. Impregnation with the binder solution may be effected by immersion after which the mat may be drained or squeezed to remove excess liquid. Treatment with the precipitant may be effected by immersion or spraying. The mat may then be dried in an oven or by passage over smooth heated rotating drums. Examples describe the preparation of a binder polymer (i) from units of polytetramethylene ether glycol, tolylene-2,4-diisocyanate. The treated mat may be printed, stencilled, embossed or dyed, and may be coated on one or both sides, e.g. with polymer or copolymers of vinyl chloride, polyurethane elastomers, or synthetic rubbers, e.g. neoprene, copolymers of butadiene and styrene, or copolymers of butadiene and acrylonitrile. Specifications 712,950, 788,560, 841,230, 849,154, 914,711, 914,712 and U.S.A. Specifications 2,515,834 and 2,758,908 are referred to. |
