Film-forming copolymers and their use in water vapor permeable coatings

摘要

A film-forming copolymer is formed by copolymerising 100 parts of a curable polyurethane resin and 10 to 100 parts of an organosilicon compound, consisting essentially of SiO2, R3SiO1/2 and R'R2SiO1/2 units, the ratio of monovalent units to tetravalent units being from 0.4/1 to 2/1 and from 40 to 90% of all monovalent units being R'R2SiO1/2 units. R is a monovalent hydrocarbon group having up to 8 carbons and R' denotes a OH-terminated polyoxyalkylene group. The invention also includes a method of making fabrics waterproof and permeable to water vapour by coating it with such copolymer.