Method for producing ethylene-vinyl ester copolymer, and saponified ethylene-vinyl ester copolymer product
The present invention provides a saponified ethylene-vinyl ester copolymer product from which a film having reduced fish eyes can be obtained and a method for producing an ethylene-vinyl ester copolymer that is a precursor thereof. At the time of producing the ethylene-vinyl ester copolymer, as a vinyl ester monomer, the oxygen concentration at storage and/or transportation is adjusted to from 2 to 8 ppm and the oxygen concentration at polymerization is adjusted to less than 2 ppm.
1. A method for producing an ethylene-vinyl ester copolymer by copolymerizing a vinyl ester monomer and ethylene, wherein the vinyl ester monomer is stored and/or transported in a state of an oxygen concentration of 2 to 8 ppm and subsequently is used for the polymerization with adjusting the oxygen concentration to less than 2 ppm.
2. The method for producing an ethylene-vinyl ester copolymer according to claim 1 , wherein the vinyl ester monomer after storage and/or transportation is copolymerized at an oxygen concentration of 1 ppm or less.
3. The method for producing an ethylene-vinyl ester copolymer according to claim 1 , wherein the vinyl ester monomer is an aliphatic vinyl ester.
4. The method for producing an ethylene-vinyl ester copolymer according to claim 1 , wherein a temperature of the vinyl ester monomer during storage and/or transportation is 38° C. or lower.
5. The method for producing an ethylene-vinyl ester copolymer according to claim 1 , wherein a pressure of the vinyl ester monomer during storage and/or transportation is 1 to 10 kPa.
6. The method for producing an ethylene-vinyl ester copolymer according to claim 2 , wherein the vinyl ester monomer is an aliphatic vinyl ester.
7. The method for producing an ethylene-vinyl ester copolymer according to claim 2 , wherein a temperature of the vinyl ester monomer during storage and/or transportation is 38° C. or lower.
8. The method for producing an ethylene-vinyl ester copolymer according to claim 2 , wherein a pressure of the vinyl ester monomer during storage and/or transportation is 1 to 10 kPa.