ETHYLENE-VINYL ALCOHOL BASED COPOLYMER AND METHOD FOR PRODUCTION THEREOF

摘要

An ethylene-vinyl alcohol based copolymer (EVOH), characterized in that it has a proportion of an ethylene unit (III) to the sum (III+IV+V) of an ethylene unit (III), a vinyl alcohol unit (IV) and a vinyl ester unit (V) of 20 to 60 mole %, and a proportion of the sun (I+II) of a carboxylic acid unit (I) and a lactone ring unit (II) in the copolymer terminal thereof to the above sum (III+IV+V) of 0.12 mole % or less; and methods for producing the above EVOH, for example, a method which comprises contacting an ethylene-vinyl ester based copolymer prior to saponification and/or EVOH after saponification with a reducing agent. The EVOH exhibits significantly improved thermal stability.