GB587914A - Production of phenolic resins - Google Patents

Abstract

Cured resins are produced by partially condensing a phenol with a compound containing an active methylene group, adding 3,5-xylenol to the resulting partial condensate and completing the condensation by heating. The phenol may be phenol, 3-methyl phenol, 2-methyl phenol, 2,3-dimethyl phenol, 2,3,5-trimethyl phenol, 2-tolyl phenol, 2-methyl, 3-ethyl phenol, 2,5-dimethyl phenol, 2-isopropyl phenol, 2-tertiary butyl-, 2-secondary amyl-, 4 - methyl-, 3,4 - dimethyl-, 3 - methyl, 4- isopropyl - phenols, long chain hydrocarbon substituted phenols, such as cardanol, best results being obtained from phenols boiling below 225 DEG C., phenol itself being preferred. The compound containing an active methylene group may be formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, acrolein, furfural, benzaldehyde, although formaldehyde, paraformaldehyde or formalin are preferred. The reactants, preferably in the presence of a catalyst, are mixed, in the fusible state, with 3,5-xylenol and cured. The catalyst may be acidic or basic, examples being hydrochloric, sulphuric, phosphoric, acetic, lactic, phthalic acids, or ammonia, ammonium hydroxide, hexamethylene tetramine and amines, more than one catalyst may be used and the preferred pH range is 5-10. The reaction may be carried out in an inert atmosphere of, e.g. nitrogen or carbon dioxide, to minimise coloration due to oxidation, and under any pressure. The amount of 3,5-xylenol used as a hardening agent is preferably 0.5-5 per cent of the weight of phenol used in the resin. Shaping is carried out before curing, or the resin composition may be applied as a coating to paper, cloth, glass, wood, brick, stone, cement, plaster, &c., or as a sizing composition for woven or felted textiles; it may be moulded or extruded, with or without admixed plasticisers, solvents, pigments, fillers, dyes, stabilisers lubricants and other synthetic or natural resins.