Method of preparation of a block copolymer and a substantially linear based on polyether and urea, urethane - -

摘要

Segmented substantially linear polyether-urethane-urea copolymers are prepared by (a) heating a difunctional hydroxyl terminated polyether with a molar insufficiency of an aromatic diisocyanate to produce a hydroxyl-terminated polyether-urethane, (b) heating the hydroxyl terminated polyether urethane with at least one mole of an aliphatic or cycloaliphatic diisocyante per equivalent of hydroxyl groups in the hydroxyl terminated polyether-urethane to produce an isocyanate terminated intermediate and (c) mixing the isocyanate-terminated intermediate with p-menthane-1,8-diamine. The polyethers preferably have a M.W. of 700 to 5,000 and those preferred are poly(oxytetramethylene) glycol and copolymers of propylene oxide with tetrahydrofuran. Suitable aromatic diisocyanates are 4,41-methylene-bis(phenylisocyanate), 4,41-methylene-bis(3-methylphenylisocyanate), a mixture of 2,4- and 2,6-toluene diisocyanates and m-phenylene diisocyanate whilst suitable aliphatic diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate and more preferably cycloaliphatic diisocyanates such as 4,41-methylene bis(cyclohexylisocyanate), cyclohexane-1,4-diisocyanate and 1,4-cyclohexane-bis(methyl isocyanate). The second stage (b) may be carried out in the presence of an organotin catalyst such as dibutylin dilaurate or stannous octoate whilst the chain extension step (c) preferably takes place in an inert organic solvent such as N,N-dimethylformamide.