GB572857A - Improvements in or relating to the manufacture of synthetic resins - Google Patents

Abstract

Thermohardening resins for use as moulding powders or, dissolved in organic solvents, as varnishes and adhesives in the preparation of laminated materials, or in the molten state for impregnating purposes, are obtained by condensing xylenols with formaldehyde in the presence of up to 25 per cent of a primary or secondary aromatic amine and an alkaline or acid catalyst, the amount of catalyst being restricted to less than 5 per cent of the xylenol in the case of inorganic catalysts and to 10 per cent in the case of organic bases. Mixed xylenols, e.g. commercial mixtures of xylenols or xylenols in which an alkyl radical replaces one or both of the methyl substituents, may be used. The formaldehyde may be replaced by its polymers or condensation products with ammonia or primary or secondary amines, and may be used in admixture with acetaldehyde or its polymers; alternatively, the reaction may be carried out in two stages, formaldehyde being used in one stage and acetaldehyde in the other stage. Catalysts specified comprise ammonia, triethanolamine, caustic soda, oxalic acid, hydrochloric acid, benzene-sulphonic acid, p-toluene sulphonic acid 0.5-3 mols. of aldehyde are used to one mol. xylenol. Aromatic amines specified comprise aniline, toluidines, naphthylamines, diphenylamine, or their mixtures. In examples: (1) 100 parts commercial xylenol, 56 parts formalin, 10 parts aniline and 9 parts ammonia are boiled together for two hours and the product dehydrated; (4) 100 parts xylenol, 20 parts paraldehyde and 1 part p-toluene sulphonic acid are refluxed for 25 mins; 45 parts formalin, 5 parts aniline, and 5 parts ammonia are then added and the mixture refluxed for 40 mins. The product is dried under vacuum. Specifications 304,659, [Class 2 (iii)], 363,694, 433,539 and 467,234 are referred to.