Patent GB-1414961-A (GB)
Title: Poromeric polyurethane coated materials
IPC: D06N3/00
Filed: 1971-07-13
Abstract: 1414961 Porous polyurethane coated material BRITISH MILLERAIN (1922) CO Ltd C A REDFARN and F W E ERWOOD 3 Oct 1972 [13 July 1971] 32882/71 Heading B2E  Poromeric laminar material is produced by applying to one side of a foraminous lamina a first substance which is such as to render the lamina impervious to the second hereinafter defined substance, applying to the other side of the lamina a second substance which comprises a polyol and a polyisocyanate having dispersed therein a finely divided solid substance that is soluble in water or organic solvent, then curing the second substance comprising the polyol and polyisocyanate from which the dispersed substance is then removed by a solvent extraction step or steps which have no destructive effect on the physical structure of the cured derivative of  the polyol and polyisocyanate which cured derivative is rendered poromeric by such removal, and removing the first substance. The dispersed particulate material may be a salt which is removed by washing with a solvent. The first substance and the salt may be removed by the same solvent in one washing operation. The polyol may be castor oil, or a blown castor oil optionally containing ethyl cellulose. The polyisocyanate may be tolylene diisocyanate. The salt may be sodium chloride. Some of the salt may be replaced by a porous precipitated silica. In a specific embodiment of the process the first substance is sodium carboxymethyl cellulose applied in aqueous solution to one side of the lamina, the lamina then being dried and coated on the other side with a substance comprising 336 parts by weight blown castor oil, 16.7 parts by weight low viscosity ethyl cellulose, 56 parts by weight sodium chloride, 7 parts by weight finely divided precipitated silica, 10 parts by weight inert pigment and 77 parts tolylene diisocyanate, the coated lamina then being heated to cure, and the sodium carboxymethyl cellulose and sodium chloride removed by washing with water. Other examples of salts are sodium sulphate and magnesium sulphate. Organic compounds including polymers may also be used as the dispersable material. Other suitable first substances are starch, gelatine, casein, methyl cellulose, methylethyl cellulose, sodium carboxy-methyl cellulose, methyl hydroxypropyl cellulose, sodium alginate and polyvinyl alcohol, polyvinyl acetate, cellulose acetate, polystyrene. The first substance may be removed by a solution in one solvent and the dispersed material of the second substance may be removed by solution in a different solvent. The applied second substance may be partially cured before applying one or more further coatings with partial curing after each coating and finally curing the whole plurality of coatings. The substrate may be fabric, natural and/or synthetic fibrous material or mixtures thereof, non-woven, e.g. felted fabrics which may be treated prior to coating by at least one of the following treatments, scouring, desizing, bleaching, singeing, dyeing, pigment padding, rot-proofing, cupra-ammonium proofing, mercerising. The substrates may be of cotton, nylon, polyethylene terephthalate, cotton spun over a continuous polyethylene terephthalate filament. The surfaces of the coated substrates may be further coated with a silicone polymer with release properties or may be lightly dusted with finely divided precipitated silica, or may be given a thin coating of a polyurethane lacquer. For use as a shoe upper material the substrate is preferably a two-way stretch fabric.