PRODUCTION OF MODIFIED ETHYLENE COPOLYMER

PURPOSE:To obtain an odorless, good-appearance, metal-containing ethylene copolymer, by saponifying an ethylene/alpha,beta-ethylenically unsaturated carboxylate ester copolymer with a basic metal compound and adding an acid anhydride to the saponificate. CONSTITUTION:A copolymer comprising ethylene and an alpha,beta-ethylenically unsaturated carboxylate ester, alpha,beta-ethylenically unsaturated carboxylate ester content 0.5-30mol%, is saponified with a basic metal compound in an organic solvent. An acid anhydride is added to this saponificate in the form of a solution, whereby a predetermined amount of this its metal carboxylate salt is converted into a carboxylic acid. As the acid anhydrides which are used in the demetalization reaction, those anhydrides are effective which are gaseous in the normal state and, which when hydrated, have an acid dissociation index (pKa) at 25 deg.C, of at least 1.5, such as carbon dioxide or sulfur dioxide. Above all, carbon dioxide gives the most uniform demetalization reaction.