GB771327A - Production of heat hardenable melamine-formaldehyde condensation products - Google Patents

Abstract

Heat-hardenable internally plasticised resins are prepared by heating together at a pH of 8-12, melamine, formaldehyde (or a polymer thereof) and a guanamine having the general formula <FORM:0771327/IV(a)/1> wherein n is an integer of 1 to 4, R1 is a phenyl, mono- or di-halophenyl, mono- or di-alkylphenyl or haloalkylphenyl group in which the alkyl group or groups have 1 to 4 carbon atoms, or a cyano or straight chain omega-cyanoalkyl group having 1 to 4 methylene groups, and each of R2, R3, R5 and R4 is a hydrogen atom or a phenyl, cresyl, xylyl, halophenyl or dihalophenyl group or an alkyl group having one to eight carbon atoms, at least one being a hydrogen atom and not more than one being a phenyl, cresyl, xylyl, halophenyl or dihalophenyl group. Many examples of such guanamines are given. The amount of formaldehyde, or polymer such as paraformaldehyde or trioxymethylene, should be from 1 to 6 equivalents per mol. of melamine, and the preferred amount of guanamine is 5 to 25 mol. per cent of melamine. The guanamine may be mixed with the other reactants before the reaction or may be added to a partially condensed melamine-formaldehyde product so long as it is allowed to condense substantially completely with the melamine and formaldehyde. The pH may be adjusted by means of sodium or potassium hydroxide, triethanolamine, benzyl trimethylammonium hydroxide or choline. Temperatures may vary from 40 DEG C. to reflux temperatures at atmospheric pressure. The resinous products, while still in the fusible state, are preferably mixed with fillers, such as glass, asbestos, paper, wood flour and cellulose, for moulding purposes, or may be dissolved in a solvent, e.g. water or wateralcohol mixtures, and used as laminating syrups. Curing is effected at temperatures of 100 DEG to 250 DEG C. with or without a catalyst. The examples describe the preparation of condensates using phenylacetoguanamine, omegacyanovaleroguanamine, 4 - N - ethyl - phenyl - valeroguanamine, omega - cyanopropioguan - amine, 4 - N - ethyl - omega - cyanovalero - guanamine, 4 - N - phenyl - cyanoacetoguana - mine, 4 - N - phenyl - phenylacetoguanamine and omega - cyanononoguanamine. Specification 642,409, [Group IV (b)], and U.S.A. Specifications 2,394,526 and 2,427,314 are referred to.