Patent GB-1122804-A (GB)
Title: Improvements relating to the production of microporous polymeric plastics materials
Inventor: BOUTLE DAVID LEONARD
IPC: C08J9/28
Filed: 1964-08-13
Abstract: A microporous plastics material is made by forming a mixture of a solution of at least one polymeric material in an organic solvent, this solution having a solid particulate filler evenly distributed through it, shaping the mixture, and treating the shaped mixture with at least one leaching agent, which is at least partially miscible with the organic solvent and simultaneously or subsequently leaching out the particulate filler.  Suitable polymeric materials are vinyl chloride polymers, e.g. a copolymer with vinylidene chloride, butadiene-styrene copolymers, polyesters, polyamides, acrylate polymers, polystyrene, and most preferably a substantially linear polyesterurethane.  Suitable solvents are dimethyl formamide, which may be removed by water and/or methanol and cyclohexanone which may be removed by method. The filler particles, which are suitably of 7 to 25 microns diameter, may be NaCl, Na2SO4, or a sugar, or a substance which may be removed by acid or alkali, e.g. a carbonate or Al2O3.  A surface-active agent which is insoluble in the leaching agents used, e.g. a bis(alkyl)sulphosuccinate, or a siloxane, may be included in the initial mixture.ALSO:A microporous plastics material e.g. artificial leather, is made by forming a mixture of a solution of at least one polymeric material in an organic solvent, this solution having a solid particulate filler evenly distributed through it.  Shaping the mixture e.g. by coating onto a support, and treating the shaped mixture with at least one leaching agent, which is at least partially miscible with the organic solvent and simultaneously or subsequently leaching out the particulate filler.  Suitable polymeric materials are vinyl chloride polymers, e.g. a copolymer with vinylidene chloride or vinyl acetate, butadiene-styrene copolymers, polyesters, polyamides, acrylate polymers, polystyrene polyvinyl formate, and most preferably a substantially linear polyesterurethane.  Suitable solvents are dimethyl formamide, which may be removed by water and/or methanol and cyclohexanone which may be removed by method.  The filler particles, which are suitably of 7 to 25 microns diameter, may be NaCl, Na2SO4, or a sugar, or a substance which may be removed by acid or alkali, e.g. a carbonate or Al2O3. A surface active agent which is insoluble in the leaching agents used, e.g. a bis(alkyl) sulphosuccinate, or a siloxane, may be included in the initial mixture.  Coating may be by extrusion, spreading, immersion, coating or spraying, and suitable substrates are porous plastic materials, woven, knitted and non-woven textile materials.  In a preferred embodiment a felt, e.g. of nylon, polyethylene terephthalate or polypropylene fibres, is impregnated with a porous polyurethane, by a method according to the invention, and is then given a microporous coating by a method according to the invention.ALSO:A microporous plastics material is made by forming a mixture of a solution of at least one polymeric material in an organic solvent, this solution having a solid particulate filler evenly distributed through it, shaping the mixture e.g. impregnating a felt with it, and treating the shaped mixture with at least one leaching agent which is at least partially miscible with the organic solvent and simultaneously or subsequently leaching out the particulate filler.  Suitable polymeric materials are vinyl chloride polymers, e.g. a copolymer with vinylidene chloride, butadiene-styrene copolymers, polyesters, polyamides, acrylate polymers, polystyrene, and most preferably a substantially linear polyesterurethane.  Suitable solvents are dimethyl formamide, which may be removed by water and/or methanol and cyclohexanone which may be removed by method.  The filler particles, which are suitably of 7 to 25 microns diameter, may be NaCl, Na2SO4, or a sugar, or a substance which may be removed by acid or alkali, e.g. a carbonate or Al2O3. A surface active agent which is insoluble in the leaching agents used, e.g. a bis(alkyl) sulphosaccinate, or a siloxane, may be included in the initial mixture.  A suitable felt may be made by mechanically entangling staple nylon, polyethylene terephalate or polypropylene fibres, and in a preferred embodiment this is impregnated with a linear polyesterurethane.