GB692722A - Novel copolymers, process for preparing such copolymers and compositions including the same - Google Patents

Abstract

Copolymers of styrene with unsaturated aliphatic carboxylic acid esters, which esters may be substituted by halogen atoms, are prepared under such conditions that the fraction of copolymer formed initially has an average molecular weight of less than 3000, an average ratio of aliphatic carbon atoms to esterified carboxylic groups of from 4 to 10, this ratio being obtained by including the carbon atoms of the carboxylic groups with the aliphatic carbon atoms, and an average ratio of esterified carboxylic groups to phenyl nuclei of at least 1.8, and maintaining conditions such that the fraction of copolymer formed in any subsequent small interval of time falls within the above molecular weight and composition limits. Unsaturated esters specified are the vinyl, allyl, isopropenyl and isobutenyl esters of formic, acetic, propionic, and butyric acids, chloroallyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, ethyl chloroacrylate, and diethyl maleate. The copolymers may also include alkenes such as ethylene, those containing 5 to 18 carbon atoms, and alkenes containing more than one unsaturated bond; the alkenes may have hydrogen atoms substituted by halogen atoms. The molecular weights of the copolymers may be kept within the desired range by means of variations in the polymerization conditions, such as the use of high temperatures, polymerization in dilute solutions, and the use of chain stoppers such as alcohols, aldehydes such as valeraldehyde, diethyl ether, acetone, chlorinated hydrocarbons such as carbon tetrachloride, chlorinated alcohols, aldehydes and ethers, esters of chlorinated organic acids such as propylchloroacetate, amines, nitro compounds, and mercaptans such as dodecyl mercaptan. Copolymers of the desired composition are obtained by charging the monomers in a ratio such that the copolymer formed initially has the desired composition, and thereafter maintaining the ratio of monomer concentrations either by stopping the reaction when the ratio of the monomers has attained a limit value, or by adding the monomers gradually to the reaction mixture as they are used up; this process may be carried out continuously by adding the monomers and subtracting the copolymer continuously. The polymerization may be carried out in bulk, solution, or emulsion with the aid of catalysts such as Friedel-Crafts catalysts, ditertiary butyl peroxide, or benzoyl peroxide. The copolymers produced are generally liquid at room temperature, and the unsaturated bonds therein may be removed by chlorination or hydrogenation. The copolymers may be used to plasticize vinyl chloride polymers and copolymers, and, mixed with oleaginous vehicles, may be used as lubricants. Specifications 617,891 and 682,254 are referred to.