CROSS-LINKING OF COPOLYMERS FROM METHYL VINYL KETONE AND n-BUTYL ACRYLATE

Abstract

Copolymers of n-butyl acrylate and methyl vinyl ketone can be cross-linked by a combination of sulphur and zinc oxide; the reaction is associated with the methyl vinyl ltetone units in the polyn~er chain. From studies on the copolymers and model conlpounds, it is suggested that adjacent pairs or groups of methyl vinyl ketone units in the polymer cyclize t o give ap ~~n s a t u r a t e d ltetone groups. These contain reactive hydrogen which is attacked by sulphur; disulphide or zinc mercaptide cross-linlts are then formed. Water is produced in the cyclization reaction and hydrolyzes some of the ester groups; additional cross-links are thus formed by reaction of the acid groups with zinc oxide. The ease of cyclization and, therefore, the extent of cross-linking is dependent on the method of preparing the copolynlers, emulsion copolymers being much more reactive than those prepared in solution. A comparison has been made between the sulphur +zinc oxide system and other cross-linking agents which may be ~~s e d for polyacrylates.

Polymerization of vinyl ketones

“…Cooper and Catterall (87) reported that copolymers of n-butylacrylate and methyl vinyl ketone could be cross-linked by a combination of sulfur and zinc oxide. It was postulated that disulfide cross-linkages…”

Cross Linking of Butadiene-Acrylate Polymers by Alkaline Earth Hydroxides

“…Many difficulties could be overcome by cross linking the ester copolymers directly with basic oxides or hydroxides. The use of such compounds for cross linking polyacrylates is known (7,7,9,12), and they would be expected to be equally effective for butadiene-acrylate copolymers.…”