Water soluble and storage stable resole-melamine resin

A resinous composition comprising a curable, clear, aqueous solution of a melamine modified phenol-formaldehyde resole resin having about 35% to 65% by weight of solids, a pH of about 9 to 10.5, less than 0.5% by weight of free formaldehyde, from about 2% to about 9% of methylolmelamines, said resin containing the resinous residue of 1.8 to 2.4 moles of formaldehyde reacted with each mole of phenol and wherein said composition has infinite water dilutability at a pH of 7.5 to 9 and an acid dilutability of less than 500 NTU, said composition prepared entirely in the alkaline range.

An alkaline, water soluble and curable resinous composition of phenol-formaldehyde resin containing less than 0.7% of free formaldehyde and which does not form precipitates when diluted with from 1 to 3 parts of water at a pH of 7.5 to 9, said resin containing the reaction product of melamine and formaldehyde formed from the reaction of melamine with a phenol-formaldehyde resin containing free formaldehyde, said composition prepared by heating at a temperature of at least 50.degree. C.:

• (A) an initial phenol-formaldehyde resole resin having about one mole of phenol condensed with about 1.8 to 2.4 moles of formaldehyde, a solids content of about 40 to 60%, a pH of about 9 to 10.5, and containing from about 0.5% to 2% of free formaldehyde;
• with
• (B) 1 to 7 parts of melamine dissolved in each 100 parts of initial resin within a molar ratio of one mole of melamine for each 0.5 to 1.2 moles of free formaldehyde to modify the initial resin by reacting the melamine with the free formaldehyde and reducing the free formaldehyde in the initial resin by at least 50%, all of said percentages and parts being by weight.

A method for preparing a curable melamine modified phenol-formaldehyde resole resin containing less than 0.7% of free formaldehyde which comprises:

• reacting about one mole of phenol with 1.8 to 2.4 moles of formaldehyde at a pH of about 9 to 10.5 in an aqueous medium to prepare an initial alkaline phenol-formaldehyde resole resin having from about 0.7 to 2.0% of free formaldehyde and 40% to 60% solids;
• dissolving melamine in the initial alkaline phenol-formaldehyde resole resin wherein the quantity of melamine is from 1 to 7 parts by weight for each 100 parts by weight of the initial phenol-formaldehyde resin and about one mole of melamine is reacted with 0.5 to 1.2 moles of free formaldehyde in the initial resin;
• and reacting melamine with the free formaldehyde in the alkaline resole resin to reduce the free formaldehyde content of the melamine modified phenol-formaldehyde resin to less than 70% of the amount in the initial resin, all of said percentages being by weight.

A C-stage glass fiber composition comprising glass fibers shaped to a desirable configuration having a cured low formaldehyde, triazine modified, phenol-formaldehyde binder applied thereto, said binder prepared by:

• (A) reacting (I) an initial aqueous, alkaline phenol-formaldehyde resole resin having a molar ratio of 1.8 to 2.4 moles of formaldehyde for each mole of phenol, from about 40 to 60% by weight of solids, about 1 to 5% by weight of free phenol and from 0.5 to 2.0% by weight of free formaldehyde with (ii) a triazine selected from the group consisting of melamine and ammeline wherein the amount of triazine is equal to about 1 to about 7 parts by weight for each 100 parts by weight of the initial resin and the molar ratio of triazine to free formaldehyde is about 1 mole of triazine for each 0.5 to 1.2 moles of free formaldehyde to prepare a triazine modified resin containing less than 0.7% by weight of free formaldehyde and wherein the free formaldehyde of the triazine modified resin is less than 70% by weight of that in the initial resin;
• and
• (B) adding water and a latent catalyst of an ammonium salt of a strong acid to the triazine modified resin to prepare a binder having about 10% to 35% by weight of solids, said binder having a pH of about 8 to 10 and wherein the amount of latent catalyst is sufficient to impart a pH of less than 6 on curing of the binder.