Silicone foams prodn. - by reacting di- or poly:isocyanate and propellant with linear organo-polysiloxane(s) in presence of tert. amine and organo-tin cpd.

摘要

Silicone foams are produced by reacting (A) di- or polyisocyanate and a propellant with (B) linear organopolylsiloxanes Y-SiR2-O-(R2SiO)n-SiR2-Y in presence of (C) a tert. amine and an organo-Sn cpd. as catalyst in an aq. medium using 0.2-20 mol water per mol (B). In the formula Y is OH and the other or both Y is/are -R'-OH; each R is independently 1-18C hydrocarbyl; n is 0-200; R' is 1-10C hydrocarbyl. B) pref. contains a dimethylorganopolysiloxane chain and is esp. HO(CH2)3-Si(CH3)O(CH3)2Si-O)5 Si(CH3)2-(CH2)3OH. Both Y are OH. The wt. ratio tert. amine:organo-Sn cpd. is 1:5 to 3:1, esp. using 0.1-3.0 wt% tert. amine and 0.1-5.0 wt% organo-Sn cpd. At least twice the molar amt. of polyisocyanate is used w.r.t. B). ADVANTAGE - Foams can be produced using a OH-functional organopolysiloxanes. The unfilled foams have a high compression strength and high tensile strength