Use of an hydrophilic polyurethane

摘要

The polyurethane (I) is hydrophilic and has a specific viscosity of at least 04 (1% aq. soln. of 20 deg.C). (I) is pref. soluble in water in all proportions at 20 deg.C, esp. in a ratio of upto 2 (wt.) pts. (I)/pt. water; and has a specific viscosity of 0.5-30, (0.7-1.5); Epprecht melt viscosity of 10-60, (40-60) Pa.s at 175 deg.C; and deg. of crystallisation of 20-80, (30-65)% w.r.t. polyethylene glycol 6000. (I) comprises units of the formulae -H(-CH2-CH2-O)n-(IA), -CO-NH-X-NH-CO- (IB) and -O-Y-O- (IC); n = 8-500, (20-300); X = a (cyclo)aliphatic gp., esp. a gp. derived from m-tetramethylxylene diisocyanate (TMXDI); Y = a hydrophobic gp., esp. (-CH2-CHMe-O)n, (-CH2-CHEt-O)n or (-CH2-CH2-CH2-CH2-O)n but also 2-44 C (cyclo)alkylene with 1,2- or alpha, omega-position of the C atoms; the amt. of (IC) being 0-40, (5-25)% w.r.t (IA)+ (IC). (I) is in the form of an aq. 1-40, (2-20)% soln. (I) is pref. prepd. by reacting the diol(s) with the diisocyanate in the melt at 80-200, (120-180) deg.C, without adding catalyst.