| abstract |
A silylated polyurethane made by the reaction of an isocyanate-terminated polyurethane a mixture of a first and a second alkoxysilane, each of which has the general formula: (CH 3 ) m (CH 3 O) 3-m Si(CH 2 ) 3 XH wherein X is NR, S, oxygen, or a ureido radical, and R is hydrogen, alkyl, aryl, aminoalkyl or trimethoxysilylpropyl, has a lower viscosity than the average of the viscosities of two polyurethanes made from the same isocyanate-terminated polyurethane and either the first alkoxysilane or the second alkoxysilane. Likewise, a blend of those two silylated polyurethanes has a lower viscosity than the viscosity anticipated by the linear viscosity relationship typically observed for blends. Said linear relationship is based on a calculation of the weighted average viscosity of the blend from the viscosity of each component and the proportion of each. |