ARTIFICIAL LEATHER

摘要

1294712 Polyurethanes TEIJIN Ltd 24 April 1970 [24 April 1969] 19874/70 Heading C3R [Also-in Divisions B1-B2] A polyurethane is derived from a polyol having a polyoxyethylene segment and a molecular weight of 600-4000, a diisocyanate and a chain extender having a molecular weight of not more than 500 and contains 15-75% of polyoxyethylene segment. A film prepared from the polyurethane has a stress at 10% elongation at 20‹ C. and 65% RH, of 0À1-2À0 kg./mm.2 and a 15 Á thick non-porous film prepared from the polyurethane has a rate of water vapour permeability of at least 3 mg./cm.2 hr. at a 19 mm. Hg. water vapour pressure difference. Numerous suitable polyols, diisocyanates and chain extenders are specified. In an example a polyoxyethylene glycol of molecular weight of 1430, which has been dehydrated, and tetramethylene glycol were dissolved in a mixed solvent of N,N-dimethyl formamide, dioxane and tetrahydrofuran and molten 4,41-diphenyl methane diisocyanate was added together with triethylene diamine as catalyst. The polymerization was conducted at 40‹ C. for 190 minutes, a mixed solvent consisting of dioxan and tetrahydrofuran added over a period of 30 minutes to dilute the reaction mixture and reaction continued for 50 minutes. A further solvent consisting of dioxan and tetrahydrofuran and containing a small amount of methanol was added and stirring continued for 40 minutes to complete polymerization. In a second example polyoxyethylene glycol of molecular weight 3000 and tetramethylene glycol are reacted with 4,41-diphenyl methane diisocyanate in the presence of triethylene diamine followed by a subsequent reaction with p-phenylene diamine.