METHOD OF PRODUCING POLY UREA FOAM CONTAINING HIGH FILLER CONTENT

1488803 Polyurea foams BAYER AG 27 May 1976 [31 May 1975] 22045/76 Heading C3R Highly filled, hydrophobic polyurea foams having a unit weight of from 10 to 200 kg./m.3 are prepared by mixing, in the presence of a polyether polysiloxane foam stabilizer and a tertiary amine catalyst, a water-insoluble polyisocyanate which is free from ionic groups, which is liquid'or is in the form of a solution or dispersion and has a viscosity of more than 200 oP/26‹ C. and a functionality of more than 2À1 with a from 30 to 80%, by weight, aqueous suspension of an inorganic filler, the suspension together with the catalyst having a pH of at least 8, at least 50%, by weight, of the suspended filler having a particle size of less than 50 microns and the weight ratio of suspension to polyisocyanate being from 1 : 2 to 6 : 1. Preferred polyisocyanates are those prepared by phosgenating an aniline/formaldehyde reaction product, followed, if desired by partly distilling off the binuclear products. Polyisocyanates containing carbodiimide, allophanate, isocyanurate, urea or biuret groups are also suitable. Suspensions used in the examples are prepared by suspending chalk, hydrate of lime, kaolin, barium sulphate, iron oxide yellow, titanium dioxide or magnesium aluminium silicate in water. The suspensions may be stabilized by the addition of dispersion stabilizers or thickeners. Blowing agents, tin catalysts and emulsifiers may also be included in the reaction mixture.