GB1529567A - Reinforced plastics material based on phenol-aldehyde resins - Google Patents

Abstract

1529567 Reinforced phenolic resins UNILEVER Ltd 30 Oct 1975 [31 Oct 1974] 47192/74 Heading C3R [Also in Division D1] Reinforced plastics comprise a fibrous base, e.g. paper, glass or textile fibres, and a cured phenol-aldehyde or phenol-ketone resin composition obtained by curing a liquid resole resin with a hydroxy arene sulphonic acid catalyst in the presence of an oxygen-containing polar organic solvent. The amount of fibrous base with respect to the dry weight of the resole and catalyst generally varies from 10- 60% wt. In an embodiment a phenol-aldehyde or phenol-ketone resin composition suitable for manufacturing reinforced plastics comprises a liquid resole resin, a hydroxy arene sulphonic acid catalyst and an organic polar solvent which is an alcohol in which any hydroxyl group is a methylol group. The oxygen-containing polar organic solvent may be inert, e.g. an alcohol, ester or nitroalkane or reactive with respect to the activated hydrogen atoms of the resole, e.g. alcohols containing a methylol group attached to a ring structure, e.g. furfuryl alcohol, benzyl alcohol and salicyl alcohol; aldehydes and ketones. The resoles are obtained by reacting an excess of an aldehyde or ketone, preferably formaldehyde, with a phenolic compound, preferably phenol in the presence of an alkaline catalyst. The catalyst may comprise one or more aromatic rings and may be a sulphonated dihydroxy diphenyl alkane, a nucleus sulphonated phenol-HCHO novolac or such novolac modified with a nitrogen containing organic compound such as urea, thiourea, dicyandiamide or melamine. The novolac catalysts may be prepared either by reacting phenol with H 2 SO 4 or chlorosulphonic acid and then with the optional nitrogencontaining organic compound and aqueous HCHO, or by sulphonating an optionally nitrogen-modified phenol-HCHO novolac or by partially sulphonating phenol before condensation with HCHO and the optional nitrogencontaining organic compound, followed by further sulphonation with H 2 SO 4 . The pot life of the resin composition can be increased by the incorporation of an organic nitrogen base such as an amine, amide or nitrile, e.g. alkylamines, melamine, aniline, acetamide, urea or acrylonitrile, either in the free form, or in the co-condensed form in the catalyst, or in the form of a sulphonic acid salt. The amount of catalyst generally ranges from 1-100 p.b.w. per 100 p.b.w. of resole. The impregnated fibrous base may be cured at ambient temperature and atmospheric pressure, or at elevated temperature and under pressure. In the examples any one of the following liquid catalysts:- (1) a sulphonated phenol/urea/ HCHO novolac alone and in admixture with either (i) glycerol, or (ii) glycerol and urea; (2) a sulphonated phenol/HCHO novolac in admixture with either (i) glycerol or (ii) glycerol and urea is mixed with a liquid phenol.HCHO resole resin alone or in admixture with either (i) benzyl alcohol, (ii) acetone or (iii) furfuraldehyde and used to impregnate glass fibre mats which are cured either under ambient conditions or at elevated temperature and under pressure. In other examples glass fibre rovings, the resole resin and the catalyst are pulverized simultaneously and then cured.