| abstract |
Prepn. of a foam from an unsatd. fast curing polyester resin of viscosity 1800-3000 cps., vinyl comonomer, finely divided bicarbonate and nucleating agent, and peroxide catalyst initiating crosslinking of the resin in 2.5-6 mins., comprises mixing the components and incorporating a 30-40% aq. inorganic orthophosphoric acid exhibiting progressively decreasing level of activity on reacting with the bicarbonate to form CO2. The acid forms salts acting as surfactant to help to sustain the foam before gelling occurs. Mixing of the components takes place at an accelerated rate to blend the acid throughout the compsn. to liberate CO2 before crosslinking has gelled the resin. |