Process for preparing a sulfite modified melamine resin solution
AssigneeSuddeutsche Kalkstickstoff-Werke Aktiengesellschaft
InventorsAlois Aignesberger, Paul Bornmann
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Abstract
The aqueous melamine resin solutions prepared according to the process of U.S. Pat. No. 2,730,516 by sequential condensation of a sulfite bearing, aqueous solution of melamine and formaldehyde at alkaline and acid pH and subsequent neutralization is stabilized by preliminary condensation of the melamine and formaldehyde prior to addition of the sulfite and by refluxing the ultimate condensation mixture at pH 8.5 for 1 hour or more. Concrete mixtures prepared with the stabilized resin solutions cure more rapidly.
Claims4
In a process for preparing a solution of sulfite modified melamine resin, wherein melamine is dissolved in aqueous formaldehyde solution at elevated temperature, the clear solution so formed is cooled, an alkali metal sulfite is dissolved in the cooled solution, the resulting sulfite bearing solution is adjusted to a pH value above 7, heated, again cooled, acidified, and heated to cause formation of said resin by condensation, and the condensation mixture obtained is adjusted to a pH value above 7, the improvement which comprises heating said condensation mixture at pH 8 to 11 for 1 to 3 hours at a temperature at which said mixture refluxes at atmospheric pressure.
Dependencies are inferred from the claim text.