GB785157A - Ion exchange resins and method of preparation thereof - Google Patents

Abstract

Porous ion exchange resins are prepared by prepolymerizing a monovinyl aromatic monomer, mixing with an unpolymerized polyvinyl compound and copolymerizing the mixture to form a hard, water-insoluble matrix which is after-treated to introduce ion-exchange groups. Specified monovinyl monomers are styrene, vinyl toluene, vinyl xylene, vinyl naphthalene, ethyl vinyl benzene and vinyl chlorobenzene. Specified polyvinyl compounds are divinyl benzene, divinyl toluene, divinyl xylene, divinyl naphthalene, trivinyl benzene, divinyl chlorobenzene, diallyl phthalate, diallyl fumarate and divinyl acetylene. The monovinyl monomers may be prepolymerized by heating, preferably in an inert atmosphere, e.g. of carbon dioxide, nitrogen, helium, argon, methane and ethane, and optionally in the presence of a catalyst, e.g. benzoyl peroxide, lauroyl peroxide, tertiary-butyl hydroperoxide, methyl ethyl ketone peroxide, tertiary-butyl perbenzoate, aluminium chloride and sulphuric acid, and then cooling to stop further polymerization. The viscosity of the prepolymer may be adjusted by adding monomer or polymers of lower or higher viscosities. Alternatively completely prepolymerized monovinyl compounds may be dissolved in the monomers. The mixtures of prepolymers and polyvinyl compounds may be copolymerized by heating in bulk or preferably in aqueous dispersion in the presence of a suspending agent, e.g. polyvinyl alcohol, starch or gum arabic, and catalyst, e.g. organic peroxides such as benzoyl peroxide, inorganic peroxides, water-soluble perborates, persulphates and perchlorates, and ozone. The copolymers may be sulphonated, e.g. with sulphuric acid, nitrated or chlorinated, e.g. with phosphorus trichloride and chlorine; or chloromethylated, e.g. with methyl chloromethyl ether and anhydrous zinc chloride, and aminated, e.g. with dimethyl ethanolamine. In examples, anion exchange resins are used to decolorize diluted molasses.