Process for obtaining urea-formaldehyde plastic foam and plastic foam obtained by the said process

摘要

The invention relates to the chemistry of polymers. The process forming the subject of the invention, of the type consisting in performing a mixing of an aqueous solution of urea-formaldehyde resin with a curing and blowing agent subjected beforehand to foaming with a compressed inert gas, the said curing agent being in the form of an aqueous solution of a surface-active agent and of an acidic catalyst, is characterised in that the aqueous solution of urea-formaldehyde resin at a concentration higher than 65 % and with a viscosity ranging up to 2500 mPa s at a temperature of 20 DEG C, is predispersed with a compressed inert gas at a pressure of (2.0-10.0)x10<5> Pa, after which the resin dispersed in this way is introduced into a stream of stable elastic foam of curing agent in a mass ratio of 1:0.5 and 1:2.5 respectively, and in that sulphonated alcohol salts of general formula: MOSO3R, where M denotes Na<+>, K<+>, NH4<+>, [(CH2CH2OH)3NH]<+> and R is a C8-C20 fatty alcohol radical, or triethanolamine salts of alkylbenzenesulphonic acid are employed as surface-active substance. The said plastic foam is employed especially as heat insulation.