PROCESS FOR THE MANUFACTURE OF POLYURETHANES

1314817 Polyurethane coating IMPERIAL CHEMICAL INDUSTRIES Ltd 26 June 1970 [24 July 1969] 37281/69 Addition to 1216661 Heading B2E [Also in Division C3] Substrates may be coated with a mixture of an organic polyisocyanate and a solution of a polyurethane containing isocyanate-reactive groups prepared by reacting in a solvent inert to isocyanate groups a mixture of an essentially linear hydroxyl-terminated polyester, polyesteramide or polyether, an at least trifunctional polyol in an amount of up to 5% by weight based on the weight of the polyester, polyesteramide or polyether and an organic diisocyanate in proportions providing 1.15 to 1.80 NCO groups per OH group to form an isocyanate-terminated product, thereafter adding a dihydric alcohol or a mixture thereof with water. The mixture containing at least 50 molar% of the dihydric alcohol in amount to provide 0.85 to 1.2 isocyanatereactive hydrogen atoms for each NCO group still remaining, continuing the reaction until a viscosity is obtained having a predetermined value of 1 to 1500 poises at 25‹C whereupon a polyfunctional isocyanate-reactive compound in which isocyanate-reactive groups of different reactivity are present is added in an amount of at least one molecule thereof for each isocyanate group present (see Division C3). Substrates which may be coated include knitted, woven or felted textiles of natural, artificial or synthetic materials, rubber, paper, wood, leather, metals, glass and plastics such as polyvinyl chloride and flexible and rigid polyurethane foams. The coating of cellulose textile materials is exemplified.