Verfahren zur Herstellung von Mischpolymerisaten fuer die Herstellung elastischer Faeden und Fasern

A substantially linear polyester-urethaneurea is prepared by (a) heating a difunctional hydroxy-terminated polyester with a molar insufficiency of an aromatic diisocyanate, (b) heating the product hydroxy-terminated polyester-urethane with an aliphatic diisocyanate, and (c) mixing the isocyanate-terminated product with p-menthane-1:8-diamine. Suitable polyesters may have M.W. between 1500 and 2500, and may be derived from e.g. malonic, succinic, terephthalic, adipic, methyladipic, maleic, sebacic and suberic acids and ethylene, propylene, trimethylene, 1:3-butylene, tetramethylene, hexamethylene, diethylene, neopentyl and decamethylene glycols. Suitable diisocyanates are 4:41-diphenylmethane-, 4:41-bis(3-methylphenyl)methane-, toluylene and m-phenylene diisocyanates and tetramethylene-, hexamethylene-, 4:41-bis(cyclohexylene)methane-, 1:4-cyclohexylene- and 1:4-dimethylene-cyclohexane - diisocyanates. Reaction (b) is preferably conducted i.p.o. an organo-tin catalyst, and reaction (c) preferably in an inert solvent, e.g. dimethylformamide, dimethylacetamide, dimethylpropionamide, dimethylsulphoxide and tetramethylurea. In examples a polyethylene adipate or polyethylene-propylene adipate diol is reacted with 4:41-methylene-bis(phenylisocyanate) and then with 4:41 - methylene - bis(cyclohexane isocyanate) and finally with p-menthane-1:8-diamine in dimethylformamide, the products being extruded into hot water to give elastic fibres.