Polyurethane-urea solns. prepn. having defined, reproducible viscosity - involves reacting di:isocyanate diol(s) and di:functional chain extender contg. amino-acidic pyrazole

摘要

The prodn. of polyurethane-urea (PU) solns. (I) is based on di-isocyanates, dihydroxy cpds. and difunctional chain extenders in the presence of inert organic solvents. The novelty is that 1-14 mol.% of a NH-acidic pyrazole of formula (II) R is H or CnH2n+1 (with n is more than 1) is added to the chain extender (III). Pref. amt. of (II) is 3-9 mol.% w.r.t. (III). (II) is 3(5)-methylpyrazole or 3,5-dimethylpyrazole, pref. a mixt. of both. Starting materials are e.g. TDI, IPDI, MDI or HDI, polyester diols, polyether-diols, polcaprolactones, etc., 2-6C glycols (III), amines, water and (II). USE/ADVANTAGE - Provides a simple means of producing 10-20 wt.% PU solns. (I) with defined, reproducible viscosity in the range 40-130 Pa.s. Suitable for the prodn. of fibres, film, coatings, adhesives and membranes. Addn. of (I) is simple and not critical w.r.t. tolerance limits; excess (I) does not lead to decomposition of the PU.