GB658301A - Polymeric products derived from diolefines and vinyl aromatic compounds and method of making same - Google Patents

Abstract

Mixed polymeric products are prepared by emulsifying with water and polymerizing in the same medium and at temperatures between 70 DEG and 110 DEG C. alternately a monovinyl aromatic compound and a conjugated diolefine, the latter in amount of 37.5 to 94.5 mol. per cent of the polymerizable compounds, and in one such reaction polymerizing in the absence of the monomeric vinyl aromatic compound at least 37.5 mol. per cent of the diolefine based on both starting materials while the emulsion contains minor amounts of hydrogen peroxide and an iron salt of an inorganic acid and enough acid to give a pH between 1.5 and 3. Specified monomers are styrene, o-, m- and p-chlorostyrenes, p-methyl-styrene, o-ethyl-styrene and p-isopropyl-styrene, and butadiene, isoprene and 2,3-dimethyl-butadiene. Mixtures of vinyl aromatic compounds and of dienes may be used. The successive polymerizations may be carried out in either order, but it is preferred to polymerize the diolefine first. When more than 37.5 mol. per cent of diolefine is employed, all or part of the excess may be copolymerized with the styrene, prior to or after polymerizing the diolefine in the absence of the monomeric vinyl aromatic compound. The polymerization of the vinyl aromatic compound, with or without the diolefin, is also preferably effected in the presence of the above complex catalyst but may be effected with other catalysts, e.g. hydrogen peroxide alone, or in the absence of catalysts. The iron salt, e.g. ferric chloride, bromide, nitrate and sulphate, and ferrous chloride and bromide, is generally employed in amounts of 0.2 to 500 parts by weight of iron per million parts of diolefine, and may be added as such or formed in situ from an iron oxide and a portion of the acid. The hydrogen peroxide is used in amount of at least 0.05 per cent of the diolefine. Emulsifying agents which may be used include a sodium salt of sulphonated sperm oil, egg albumen and alkali metal sulphonates of aliphatic hydrocarbons or alkyl-aromatic hydrocarbons of high molecular weight. Rubber anti-oxidants, e.g. phenyl-beta-naphthylamine, di - (p - hydroxyphenyl) - cyclohexane, p,p1 - dimethoxy-diphenylamine or a condensation product of aniline and butyraldehyde, are added, preferably after polymerization. The products are coagulated by freezing or by adding aqueous hydrochloric or sulphuric acid or a salt, washed and dried. They may be moulded to obtain smooth, flexible articles, milled into sheets and used as electrical insulating coatings. The materials may also be vulcanized to render them non-thermoplastic but still flexible.