Abstract: A process for producing stable urea-aldehyde polymers with high structural strength from two storable liquid ingredients. In this process, partially cured liquid urea-formaldehyde resin is reacted with an aqueous cross-linking solution comprising one or more alkyl or aryl dialdehydes containing two to eight molecular carbons and the hydrogen ion concentration needed to catalyze the completion of the reaction of the dialdehydes and the urea-formaldehyde. The process for producing urea-aldehyde polymers, having improved structural strength and reduced aldehyde vapor emission during their production and prolonged use, is especially effective for manufacturing products for the building industry, such as urea-aldehyde insulating foam, wood-filled particle board, and plywood. The increased polymer strength and the elimination of the hazardous and objectionable aldehyde odor is achieved by maintaining the molecular ratio of total aldehyde moieties to urea to about 1.

Abstract: Method of producing a substantially chemically stable urea-formaldehyde foam which comprises preparing a partially cured aqueous urea-formaldehyde resin, modifying the partially cured resin by reacting at pH 4.5 - 5.5 and 70.degree.-110.degree. C with aqueous dialdehyde containing two to six molecular carbons and additional urea with each additive amounting to 1-5 per cent by weight of the modified resin, neutralizing the modified resin to pH 6.7 - 7.5 by addition of aqueous alkali hydroxides or carbonates, combining said neutral modified resin with a froth produced by forcing air through a dilute acidic aqueous surfactant solution to re-activate and complete the cure of the modified resin in the foam, and drying the foam.Glyoxal is the preferred dialdehyde for modifying the urea-formaldehyde foam resin because of its effectiveness at increasing chemical stability of the foam at levels as low as 1.0 per cent.

Abstract: Method of producing a dimensionally stabilized urea-formaldehyde foam which comprises preparing a neutral concentrated partially cured aqueous urea-formaldehyde resin, combining said neutral resin with a froth produced by forcing air through a dilute acidic aqueous surfactant solution to activate the urea-formaldehyde foam cure, immediately thereafter combining the curing urea-formaldehyde foam with a substantially non-ionic liquid additive containing dissolved urea and suspended linearly shaped refractory solid particles, completing the acid catalyzed foam cure, and drying. Foam dimensional stability is maximized when the non-ionic liquid additive contains 10-20% by weight dissolved urea and 10-20% by weight suspended attapulgite clay.