GB884033A - Process for the preparation of epoxide resins - Google Patents

Abstract

Epoxy resins are prepared by heating a haloepoxyalkane with a polycarboxylic acid, or a polycarboxylic acid anhydride together with water and/or a polyhydric alcohol, in the presence of an organic catalyst of high molecular weight which is insoluble in the reaction mixture and which contains either a salt-like group or a group convertible to a salt-like group under the reaction conditions or an acid amide group. After the catalyst has been separated, excess haloepoxyalkane and volatile products are distilled off. More than 2 mols. and preferably 5-40 mols. of haloepoxyalkane are used per carboxyl group, or more than 4 mols. and preferably 10-50 mols. of haloepoxyalkane per acid anhydride group. When a polycarboxylic acid anhydride is used it may be heated with water and/or a polyhydric alcohol, with or without the haloepoxyalkane, before the addition of the catalyst. The catalyst may be wet or dry and the reaction mixture may contain up to 3% of water over and above any water present for the hydrolysis of a polycarboxylic acid anhydride. Many polycarboxylic acids, polycarboxylic acid anhydrides, haloepoxyalkanes and polyhydric alcohols are specified. The preferred polyols are those which contain one halogen atom and two hydroxyl groups and are derived p from the haloepoxyalkane by replacing the epoxide group by two hydroxyl groups. The catalysts may be the salts of cation exchange resins, anion exchange resins or their salts, mixed-bed ion exchange resins, amphoteric ion exchange resins, melamine resins, aminecured epoxy resins, polyamides or proteins. The catalyst is first graded to remove fines. In a typical example phthalic acid and epichlorohydrin are refluxed with a commercial, water-containing anion exchanger based on polystyrene and containing quaternary benzyl ammonium groups. In another example, castor oil, glycerol and phthalic anhydride are heated together to give an acid ester which is heated with epichlorohydrin in the presence of an anion exchange resin containing quaternary ammonium groups. In a similar example, the acid ester used is prepared by heating ethoxylated methylcellulose with phthalic anhydride under nitrogen. The epoxide oxygen content of the products may be increased by dehydrohalogenation using sodium hydroxide in methylene chloride or by treating the product with a further amount of epichlorohydrin by the process of this invention. The products may be bleached by organic peroxides and cured by curing agents such as, e.g. amines and acid anhydrides. They may be used as adhesives, casting resins, or lacquer resins, or for the manufacture of laminates or glass fibre reinforced materials.ALSO:Epoxy esters generally containing some halogen are prepared by heating a haloepoxyalkane with a polycarboxylic acid, or with a p polycarboxylic acid anhydride together with water and/or a polyhydric alcohol, in the presence of an organic catalyst of high molecular weight which is insoluble in the reaction mixture and which contains either a saltlike group or a group convertible to a saltlike group under the reaction conditions or an acid amide group. After the catalyst has been separated, excess haloepoxyalkane and volatile products are distilled off. More than 2 mol and preferably 5-40 mol of haloepoxyalkane are used per carboxyl group, or more than 4 mol and preferably 10-50 mol of haloepoxyalkane are used per acid anhydride group. When a polycarboxylic acid anhydride is used it may be heated with water and/or a polyhydric alcohol with or without the haloepoxyalkane before the addition of the catalyst. The catalyst may be wet or dry and the reaction mixture may contain up to 3% of water over and above any water present for the hydrolysis of a polycarboxylic acid anhydride. Many polycarboxylic acids, polycarboxylic acid anhydrides, haloepoxyalkanes and polyhydric alcohols are specified. The acids may be substituted, e.g. by ether, ester or hydroxyl groups. The preferred polyols are those containing one halogen atom and two hydroxyl groups and which are derived from the haloepoxyalkane by replacing the epoxide group by two hydroxyl groups. The catalysts may be the salts of cation exchange resins, anion exchange resins or their salts, mixed lead ion exchange resins, amphoteric ion exchange resins, melamine resins, aminecured epoxy resins, polyamides or proteins. The catalyst is first graded to remove fines. In a typical example phthalic acid and epichlorohydrin are refluxed with a commercial, water-containing anion exchanger based on polystyrene and containing quaternary benzyl ammonium groups. In another example, castor oil, glycerol and phthalic anhydride are heated together to give an acid ester which is heated with epichlorohydrin in the presence of an anion exchange resin containing quaternary ammonium groups. The epoxide oxygen content of the products may be increased by dehydrohalogenation using sodium hydroxide in methylene chloride or by treating the product with a further amount of epichlorohydrin by the process of this invention. The products may be bleached by organic peroxides and cured by curing agents such as, e.g., amines and acid anhydrides. They may be used as adhesives, casting resins, or lacquer resins, or for the manufacture of laminates or fibre glass reinforced materials.