Polyurethane foams and elastomers prepared from low molecular weight polyhydroxyl compounds

Abstract

Abstract This invention relates to an improved process for the production of a mixture of low molecular weight polyhydric alcohols, hydroxy aldehydes and hydroxy ketones by condensing formaldehyde hydrate in the presence of calcium hydroxide as catalyst and in the presence of compounds capable of enediol formation as co-catalyst. A formaldehyde-containing enediol formation as co-catalyst. A formaldehyde containing solution of the co-catalyst in water and, optionally, low molecular weight monohydric or polyhydric alcohols and/or relatively high molecular weight polyhydroxyl compounds is adjusted to a pH value of from 9 to 12, preferably from 9 to 10, by the addition of calcium hydroxide at a temperature of from 80° to 110° C., preferably from 90° to 105° C., so that condensation of the formaldehyde hydrate is initiated. An aqueous formalin solution and/or paraformaldehyde dispersion containing from 20 to 65%, by weight, of formaldehyde and calcium hydroxide are then introduced in such a quantity that the reaction mixture is maintained at a pH value of from 7.5 to 9.5, preferably from 8 to 9, at a temperature of from 80° to 110° C., preferably from 90° to 105° C. The concentration of formaldehyde is maintained at from 0.5 to 10%, by weight, preferably from 1.2 to 6%, by weight, based on the reaction mixture as a whole, throughout the condensation reaction. Finally, the residual quantity of formaldehyde, amounting to from 0.5 to 10%, by weight, is optionally removed by further condensation at pH values below 7 or by reaction with other compounds that are reactive with formaldehyde hydrate.

Inventors

• 👤 Hanns P. Muller
• 👤 Kuno Wagner

Bibliographic Details