GB785930A - Thermosetting etherified resins - Google Patents

Abstract

An etherified thermosetting resin is produced by condensing 1 mol. of a reactive monohydric phenol with 0.5-0.75 mol. of formaldehyde at a temperature above 80 DEG C. and in the presence of 1/200 -\ba1/10 of an equivalent of alkaline condensing agent (based on the phenol) until substantially all the formaldehyde has condensed and thereafter etherifying the condensate in an alkaline medium at a temperature not above 100 DEG C. with an amount of epihalogenhydrin or dihalogenhydrin in excess of the amount equivalent to the phenolic hydroxyl groups in the reaction mixture. A list of suitable phenols is given. Phenol or m-cresol is preferred. Aqueous formalin or paraformaldehyde may be used. Preferred alkaline catalysts are alkali or alkaline earth metal or ammonium hydroxides. Etherification may be arrested by neutralization of the alkaline medium and/or by separation of the etherified product. Completely etherified products usually separate from aqueous media and may be dehydrated and purified by distillation, e.g. azeotropic at atmospheric or reduced pressure. The products which may be soluble in "Cellosolve" (Registered Trade Mark), dioxan or cyclohexanone have low viscosities and are particularly useful for glass fibre laminates. They may be cured by heating with conventional catalysts, e.g. weak acids, triethylamine, pyridine, piperidine, ethylene diamine, diethylaminoethylamine, b -dimethylaminopropionitrile dicyandiamide, or benzyldimethylamine. Detailed examples are given of the preparation of ethers from phenol-formaldehyde condensates and epichlorhydrin and of their use as casting resins, as adhesives for metal, and for preparing glass fabric laminates. Belgian Specification 503,549 is referred to.