Acrylate-modified melamine resin which is stable on storage, its preparation and its use

Low viscosity, aqueous impregnating resin solution with improved stability containing 30-70% by weight of solid resin which comprises:

• (A) 80-98% by weight of a melamine-formaldehyde precondensate and
• (B) 2-20% by weight of a water soluble copolymer,
• wherein the melamine-formaldehyde precondensate (A) has a molar ratio of melamine:formaldehyde of 1:1.4-2.6 and contains 0.2-1% by weight, relative to solids content, of an amine of the formula ##STR6## wherein R.sup.1 and R.sup.2 are identical or different alkyl moieties having 1-4 carbon atoms and R.sup.3 is 2-hydroxyethyl, 2-(2-hydroxyethoxy)-ethyl, 3-hydroxy-1-propyl, 3-hydroxy-2-propyl, 2,3-dihydroxypropyl or ##STR7## said amine being present wholly or partially in the form of its reaction product with the melamine-formaldehyde precondensate, and
• wherein said water soluble copolymer (B) is formed from the copolymerization of
• (a) 0-55% by weight of an ester of acrylic acid, methacrylic acid, crotonic acid, maleic acid or itaconic acid and an alcohol having 1-4 carbon atoms, acrylonitrile, methacrylonitrile or mixtures thereof,
• (b) 25-100% by weight of a hydroxyethyl or hydroxypropyl ester of at least one acid selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, maleic acid and itaconic acid;
• an ester of said acid with glycidol;
• or mixtures thereof;
• and
• (c) 0-25% by weight of at least one member selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, acrylamide, methacrylamide, crotonamide and maleic acid half-amide, and wherein said water-soluble polymer is adjusted to a pH-value of 7.1 to 8.5 by means of organic amines of the general formula ##STR8## wherein R.sup.1 and R.sup.2 have the meanings given above.