GB1105907A - Elastic fibres having hindered tertiary radicals in the polymer chain - Google Patents

Abstract

In an elastic fibrous segmented polyurethane or polyurea, containing 50-95% soft segments and 5-50% hard segments joined by urethane or urea linkages at least 12% by weight of the total hard segments are divalent hindered tertiary radicals of formula <FORM:1105907/C3/1> each of which is attached to NH, and wherein R11 is methyl, ethyl or n-propyl and X is pphenylene, p-xylylene, 1,4-cyclohexylene, 4,41biphenylene or <FORM:1105907/C3/2> in which Y is -CH2-, -CH2CH2-, -O-, -C(CH3)2-, -S-, -SO-, or -SO2-. If desired the group which X represents may have at least one ring substituent of the class consisting of methyl, methoxy and ethyl. The soft segments consist of the residue remaining after removal of the terminal activehydrogen containing groups from an amorphous polymer melting below 60 DEG C. and having a mol. wt. above 600. The hard segments contain at least one unit which is the repeating unit of a nitrogen-containing polymer which in its fibre-forming mol. wt. range would melt above 200 DEG C. The polymers are prepared by reacting a hydroxyl- or amino-terminated polymer having a mol. wt. above 600 and a melting point above 60 degrees with excess organic polyisocyanate, R(NCO)y where y is 2-4, to give an isocyanate terminated polymer. Catalysts may be used where the polymer is hydroxylterminated. At least 80 mol. per cent of the radicals R are divalent radicals terminating at carbon atoms which are not part of an aromatic ring. They may be, at least in part, of the hindered tertiary type (see U.S. Patent 2,723,265 and British Patent 942,158). The isocyanate terminated polymer is chain-extended with a diamine, which may be of the hindered tertiary type, or with hydrazine, a dihydrazide, a glycol, water, or piperazines. A plurality of chain extenders may be used in admixture or sequentially. Monomeric diisocyanate may be added during the chain extension reaction. The molecular weight of the final polymer may be controlled by addition of a chain terminator e.g. diethylamine. The polymers are prepared by conventional techniques, e.g. solution polymerization or as described in Specifications 849,154 and 849,156. They may be made from diamines and bichloroformates of glycols, the hindered tertiary radicals being obtained from the diamines. When solution polymerization is used the resulting solutions may be directly spun to elastic filaments. Preferred polymers are substantially linear but they may be slightly cross-linked or branched by using reactants with functionalities greater than 2. They may also be cross-linked after shaping e.g. by reaction with di-isocyanate. In a typical example, an isocyanate terminated polymer is formed from polytetramethylene ether glycol and a ,a ,a 1,a 1-tetramethyl-p-xylylene di-isocyanate, using dibutyl tin laurate as catalyst. The polymer is dissolved in N,N-dimethylacetamide and chain extended with 1,3 - diaminocyclohexane (70/30 cis/trans isomers).