Th. Goldschmidt Ag

Dieter Hellwig

Ulrich Holtschmidt

Eckehard Schamberg

Arnold Laqua

A method for preparing thermosettable urea-formaldehyde resins having a urea to formaldehyde molar ratio of 1:1 to 1:1.5 wherein urea and formaldehyde are first reacted in an aqueous solution at a molar ratio of 1:1.5 to 1:4 in the pH range between 7.5 to 10, and then condensing the reactants in a pH range from 4 to 6 to a precipitation number of 1:1.5 to 1:10, thereafter adjusting the pH to 7 to 10 and adding the remaining urea to obtain a molar ratio of 1:1 to 1:1.5 and continuing the reaction until a precipitation number of 1:0.5 to 1:3 is obtained. The products obtained have a uniform molecular weight and good penetration properties when used to impregnate supporting webs for coating wood-based panels.

Process for the preparation of thermosettable urea-formaldehyde resins

A method for the preparation of hardenable urea-formaldehyde resins for use in impregnating and coating carrier webs wherein urea and formaldehyde are first reacted in the presence of an aminosulfonic acid and ammonia, additional aminosulfonic acid is added and the mixture is further reacted to adjust the viscosity of the solution and then additional ammonia and urea are added to the reaction mixture and the mixture is further reacted to adjust the viscosity thereof, and wherein a polymer formed from the monomers of the formula ##STR1## in which R.sup.1 =H or CH.sub.3,

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Bochum, Germany

Dieter Hellwig