Aliphatic silylated polyurethane mixtures having reduced viscosities

摘要

A silylated polyurethane mixt. having a viscosity less than the weighted average of the viscosities of the constituent silylated-polyurethanes comprises polyurethanes of formula (CH3)m(CH3O)3-mSi(CH2)3X[C(O)NHYNHC(O)ZC(O)NHYNHC(O)]- -X'(CH2)3Si(OCH3)3-n(CH3)n (I). In (I), m and n = 0 or 1; X = NR, S, O or a ureido radical; R = H, alkyl, aryl, aminoalkyl or trimethoxysilylpropyl; Y = urethane residue; and Z = polyol residue; provided that at least one of m, n, X or R in the first silylated polyurethane is different than it is in the second silylated polyurethane. Also claimed are: (i) a polyurethane of formula (I); and (ii) a sealant compsn. comprising the above polyurethane mixt., filler and a curing catalyst. Pref. the first polyurethane contains a silyl gp. A and the second polyurethane contains silyl gp. B. A and B are either (CH3)m(CH3O)3-mSi(CH2)3X or -X(CH2)3Si(OCH3)3-n(CH3)n.