Patent GB-849669-A (GB)
Title: Polymers and the preparation thereof
IPC: C08F8/00
Filed: 1956-12-19
Abstract: Polymers having anhydride groups on the main chain of a polymer containing carboxyl groups are prepared by treating with a dehydrating agent (A) a substantially dry homopolymer of an alpha-beta unsaturated monocarboxylic acid having the general formula:  <FORM:0849669/IV(a)/1> in which R is hydrogen, chlorine, bromine, fluorine, a - CN group, a C1-C10 alkyl group, an aryl group, an aralkyl group or an alkaryl group and R1 is hydrogen, chlorine, bromine or fluorine, or a copolymer derived from a mixture of such acids, or a copolymer of at least one molar equivalent of said acid with at least one other monomer copolymerisable therewith; or (B) at least one substantially anhydrous or glacial unsaturated acid of the above general formula, or a mixture of such acids, or a mixture of at least one molar equivalent of such acid with at least one other monomer copolymerisable therewith, the polymer (A) being treated with a dehydrating agent for a time and at a temperature sufficient to convert at least about 10% of the carboxyl groups of the polymer to anhydride groups and the monomeric material (B) being treated with a dehydrating agent which is not copolymerisable therewith in the presence of a polymerisation catalyst and under polymerising conditions.  Preferred acids of the above general formula are acrylic, methacrylic, chloroacrylic and cyanoacrylic acids.  Other monomers specified are maleic anhydride and its monochloro and dichloro derivatives, beta-alkyl acrylic acids, beta-chloro, bromo, fluoro and cyano acrylic and methacrylic acids, crotonic, angelic, tiglic and cinnamic acids, beta-benzyl and tolyl acrylic acids 2,3-diethyl and dipropyl acrylic acids, vinyl alkyl ethers, vinyl esters and polyunsaturated cross-linking monomers such as divinyl benzene and cyclohexane, low molecular weight polybutadiene, hexaallyl trimethylene sulphone, triallyl cyanurate, trimethacrylyl triazine, methylene-bis-acrylamide, diallyl acrylamide, acrylic anhydride, beta-styryl acrylic acid, ethylene glycol diacrylate, allyl acrylate and cinnamate, diallyl phthalate, malonate and succinate, monoallyl maleate, divinyl and diallyl ketones, allyl-beta-allyloxy propionate and vinyl, allyl, methallyl and crotyl polyethers of polyalcohols, e.g. allyl ethers of glycerol, erythritol, pentaerythritol, sorbitol, mannitol and various specified saccharides.  Dehydrating agents specified are the anhydrides of aliphatic and aromatic mono- and poly-carboxylic acids (listed), especially acetic anhydride, phosphorus tri- and penta-chloride and bromide, phosphorus oxychloride and oxybromide, phosphorus pentoxide, thionyl chloride and sulphuric acid.  When dehydration and polymerisation are effected simultaneously it is done so preferably in an inert organic solvent in the presence of a catalyst such as benzoyl or caprylyl peroxide or azobisisobutyronitrile.  The resulting polymers contain alpha-methylene glutaric anhydride groups and may be used in the production of solvent-resistant coatings or, in the p  form of their partial alkali metal salts, viscous aqueous mucilages.  Specification 533,497 is referred to.