GB566347A - Water-soluble melamine-formaldehyde resins and processes of preparing the same - Google Patents

Abstract

Water-soluble methylated methylolmelamine resins are obtained by reacting, under acid conditions, a polymethylolmelamine with methyl alcohol until a clear solution is obtained, then neutralizing the solution and dehydrating the neutralized solution under high vacuum. In examples: (1) dry hexamethylolmelamine is heated with methanol, in the presence of oxalic acid, under reflux and gently boiled until a clear solution is obtained which is then neutralized by dilute caustic soda, clarified by filtration and dehydrated, first by heating at 40-50 DEG C. under moderate vacuum and continuing until a temperature of 90 DEG C. is attained under a vacuum of 28-29"; the resulting syrup may be poured into pans and allowed to cool to a solid resin, or admixed with water to give a stable solution; (2) 10 mols. of aqueous formaldehyde and 3 mols. of melamine, made slightly alkaline with caustic soda, are heated under reflux to form a clear solution, whereupon methanol and oxalic acid are added, the mixture gently boiled for a few minutes, cooled, clarified by filtration and dehydrated under vacuum. The aqueous solutions of the resins are useful in the treatment of textiles and may be admixed with water-soluble alkyds or methyl cellulose; the solid resins may be used for the production of laminated material, or as flow promoters for urea-aldehyde and triazine aldehyde resins. Thus a methylol melamine is prepared by adjusting a mixture of 1 mol. melamine and 6.5 mols. 37 per cent formaldehyde to a pH 8.8-9 and heating to 80 DEG C. in 30 mins. and keeping at 80 DEG C. for 15 mins. The mixture is then poured into trays and dried at 40-50 DEG C. Specifications 468,677 and 486,577 are referred to.