GB698179A - Compositions comprising acid-curing thermosetting aminoplast resins - Google Patents

Abstract

A moulding or coating composition comprises an acid-curing amino-plast condensate or resin and a curing catalyst which is the salt of a quaternary hexamethylenetetramine base having the formula (C6H12N4)mRnXp where R is an alkyl, alkylene, alkanyl, alkylidene, cycloalkyl, or aryl substituted aliphatic hydrocarbon radical, or a monosubstituted alkyl group in which the substitutent is an alkoxy, amino-carbonyl, aryl-carbonyl, alkoxy-carbonyl or aryloxy-carbonyl radical, X is the anion of an acid which will act as a curing catalyst and either p = 1, m = 1 and n = 1 or p = 1, m = 2 and n = 2 or p = 2, m = 2 and n = 1. R may be, for example, methyl, methylene, ethyl, isopropyl, hexyl, isopropyl, hexyl, heptyl, cetyl, cyclohexyl, allyl, benzyl, carbamylethyl, carbethoxymethyl, carbophenoxymethyl, benzoylmethyl and methoxymethyl, and X may be chloride, bromide, iodide, sulphate, benzene sulphonate, chromate, dichymate, thiocyanate formate and benzoate. The catalysts are stated to become active only at moulding temperatures so that the compositions are normally stable. Resins referred to are those derived from aldehydes and urea, thiourea, the reaction products obtained by the pyrolysis of dicyandiamide, melamine and other aminotriagines, and co-condensates of these resins. Fillers referred to are wood flour, asbestos, cotton linters, regenerated cellulose and clay. Pigments, lubricants such as zinc stearate, starches, gums, alginates and casein may also be incorporated. Examples: (1) 35 parts cellulose pulp filler, 65 parts urea-formaldehyde reaction product, 0.25 parts methyl hexamine iodide; (2) as (1) but with 0.5 parts cetyl hexamine iodide; (3) as (1) but with 0.25 parts ethyl hexamine iodide; (4) 30 parts cellulose pulp filler, 70 parts of a melamine-urea-formaldehyde reaction product in which the melamine to urea molar ratio was 1 to 9, and 0.5 parts cetyl hexamine iodide. 0.01 to 0.1 per cent by weight of the composition of hexamine may be added as a pH stabilizer. The curing agents are stated to produce products of improved water resistance and where R is a high molecular weight aliphatic radical, e.g. cetyl, this is stated to act as a mould lubricant.ALSO:Quaternary hexamethylenetetramine salts having the general formula (C6H12N4)mRnXp, where R is an alkyl, alkylene, alkenyl, alkylidene, cycloalkyl, or aryl-substituted aliphatic hydrocarbon radical, or a monosubstituted alkyl group in which the substituent is an alkyloxy, aminocarbonyl, arylcarbonyl, alkoxycarbonyl or aryloxycarbonyl radical, X is the anion of an acid and either p=1, m=1 and n=1, or p=1, m=2 and n=2, or p=2, m=2 and n=1, are made by mixing solutions of hexamethylenetetramine and the appropriate RX compound in correct proportions, allowing the mixture to stand for a few hours to several weeks, filtering, rinsing and drying the precipitated salt. Chloroform is a suitable solvent. Sometimes an excess of the RX compound is desirable. Examples of R are:-methyl, methylene, ethyl, isopropyl, hexyl, heptyl, cetyl, cyclohexyl, allyl, benzyl, carbamylmethyl, carbethoxymethyl, carbophenoxymethyl, benzoylmethyl and methoxymethyl. Examples of X are:-chloride, bromide, iodide, sulphate, benzene sulphonate, chromate, dichromate, thiocyanate, formate and benzoate. The Specification lists seventeen particular compounds. The salts are useful as curing catalysts for aminoplast condensates or resins.