GB771926A - Graft copolymers - Google Patents

Abstract

Graft copolymers are prepared by heating a polymerizable cyclic ether in a substantially anhydrous medium containing a hydroxyalkylated polystyrene with an alkali metal oxide, hydroxide, hydride or alkoxide catalyst. The cyclic ether, which must be capable of polymerizing by opening the ring under the influence of a basic catalyst, may be ethylene oxide, mono-substituted derivatives, e.g. propylene oxide, 1,2-epoxybutane, 1,2-epoxybutene and trimethylene oxide and less reactive compounds such as phenylethylene oxide. The hydroxyalkylated polystyrenes contain alcoholic hydroxyl groups obtained by forming b or g -hydroxyl-alkyl esters from the free carboxylic acid groups in a copolymer of styrene and an unsaturated carboxylic acid, e.g. acrylic, methacrylic, cinnamic and maleic acids consisting of chains of 10 to 100 polymerized styrene units per free carboxylic acid and preferably prepared by reacting the copolymer in an anhydrous solvent with one to three molar proportions of cyclic ether with a basic catalyst, e.g. pyridine, as described in Specification 771,569. The graft copolymers are prepared at elevated temperature, preferably 100-160 DEG C., and pressure, in solvents such as benzene or toluene, and the products recovered by distilling off the solvent and extracting with water. In a preferred preparation formation of the hydroxy-alkylated polystyrene and the graft copolymerization take place in successive stages using first a weakly basic catalyst, e.g. a tertiary amine, and then adding a strongly basic catalyst with the polymerizable cyclic ether present in at least a fourfold excess. Alternatively the two catalysts may be used in admixture. The products may be used as coatings, laminate adhesives, antistatic agents for polystyrene, applied to the surface or incorporated in the moulding, or may be cross-linked with di-isocyanates, e.g. 2,4-tolylene diisocyanate, to give elastic products suitable for foils and films.