Polyol compositions containing mould release agent

Claim 1

A stable polyol composition for use in reaction injection moulding (RIM) processing of polyurethanes, said composition consisting essentially on a weight basis of: (a) 100 parts of a polymeric polyol selected from polyoxypropylene diols and triols and poly(oxypropyleneoxyethylene) diols and triols having hydroxyl equivalent weights of from 750 to 3000 and mixtures thereof; (b) 1 to 10 parts of a polysiloxane mould release agent which consists essentially of 0.5-20 mol % of R a R' b SiO [4-(a+b)]/2 units and from 99.5-80 mol % of R" c SiO(4-c)/2 units where R is an isocyanate reactive organic radical, a has an average value of from 1-3, R' and R" are hydrocarbon radical or a substituted organic radical, b has an average value of 0-2, a+b is from 1-3, c has an average value from 1 to 3, whereas (i) the ratio of the total molecular weight to the total number of isocyanate reactive functional groups in the polysiloxane molecule ranges from 100-3500, (ii) the combined formula weights of all isocyanate reactive organic radicals R do not exceed 40% of the total molecular weight of the polysiloxane mould release agent, (iii) the combined formula weights of all non-isocyanate reactive radicals R' and R" together do not exceed 40% of the total molecular weight of the polysiloxane mould release agent; (c) 1 to 5 parts of an ethylene oxide based surfactant having the formula QO(CH.sub.2 CH.sub.2 O).sub.n H wherein Q represents an alkyl, alkylphenyl or alkanoyl residue containing from 8 to 30 carbon atoms and n has an average value of from 20 to 150.