Method for producing dimensionally stable urea-formaldehyde foams
AssigneeWaverly Chemical Co.
InventorWilliam Percy Moore
Life of this patent
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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.
Claims1
A method for producing dimensionally stable urea-formaldehyde foam which comprises an aqueous neutral urea-formaldehyde resin having a formaldehyde to urea mol ratio of about 2, a viscosity of about 40 centipoise and a solids content between 40 and 65%, combining the said resin with frothed curing solution containing about 1% sulfuric acid and about 2% surfactant and having an electrical conductivity of at least 0.1 ohm.sup.-1 centimeter.sup.-1, continuously blending the combined resin and curing solution foam with a substantially un-ionized liquid suspension having an electrical conductivity lower than 0.00001 ohms.sup.-1 centimeter.sup.-1 and containing between 10 and 25% attapulgite clay sized to pass through a 325 mesh Tyler Screen, curing and drying the combined foam at temperatures between 0.degree. C and 35.degree. C.
Dependencies are inferred from the claim text.