Highly filled polyurea foams

A process for the production of highly filled hydrophobic, hard polyurea foams with gross densities of from 10 to 100 Kg/M.sup.3 comprising reacting

• (a) a polyisocyanate, said polyisocyanate being a liquid water insoluble polyisocyanate, free from ionic groups or groups which are capable of forming ionic groups during the process, said polyisocyanate having a viscosity of more than 200 cP at 25.degree. C, a functionality of greater than 2.1, and an NCO-content of from 20 to 32% by weight, said polyisocyanate being selected from the group consisting of
• (i) phosgenation products of condensates of aniline or anilines alkyl substituted on the nucleus with aldehydes or ketones,
• (ii) solutions of distillation residues accumulating during the production of tolylene diisocyanate, diphenylmethane diisocyanate, or hexamethylene diisocyanate, in monomeric polyisocyanates or in organic solvents,
• (iii) mixtures of said distillation residues,
• (iv) modified polyisocyanates containing carbodiimide groups, allophanate groups, isocyanurate groups, urea groups, or biuret groups, said modified polyisocyanate prepared by modifying polyisocyanates thermally or catalytically by air, water, urethanes, alcohols, amides or amines,
• (v) semi-prepolymers obtained by reacting polyisocyanates (i) through (iv) with glycols or polyols, said semi-prepolymer polyisocyanates containing less than 10% by weight of polyols;
• (b) a aqueous suspension of inert minerals or hydraulic binders, said suspension having a solids content of from 30 to 80% by weight, at least 50% by weight of the suspended fillers having the particle size of less than 50 microns;
• (c) in the presence of a polyether/polysiloxane foam stabilizer, and in the presence of a tertiary amine catalyst, the weight ratio of component (b) to component (a) being between 1:2 and 6:1, the pH value of the aqueous suspension, together with the tertiary amine catalyst, being above 8.