| 摘要 |
1,253,760. Films. AVCO CORP. 4 Sept., 1969 [6 Sept., 1968], No. 43930/69. Heading B5B. [Also in Divisions A5 and C3] Flat and tubular films may be cast from solutions of block copolymers containing polysiloxane and polyetherurethane of polyesterurethane segments joined by Si-N bonds. In examples tubes are cast on polished stainless steel mandrels, either simply or followed by wrapping with a polyester fabric or nylon filament and a second cast film of the copolymer, using solutions of a copolymer containing dimethylsiloxane segments and polyurethane segments derived from polypropylene glycol and toluene diisocyanate. Flat films are prepared by casting solutions on to a flat surface, allowing them to dry in air at room temperature, curing the block copolymer by heating at 60‹ C. for 1 hour and finally stripping the films from the smooth surface. |
