Ethylene-vinyl alcohol copolymer resin composition, and multilayer structure

An ethylene-vinyl alcohol copolymer resin composition comprising:

• an ethylene-vinyl alcohol copolymer;
• and
• from 5 ppm to 300 ppm of a lubricant based on the weight of the ethylene-vinyl alcohol copolymer resin composition;
• wherein the ethylene-vinyl alcohol copolymer comprises monomer units including at least an ethylene unit and a vinyl alcohol unit, and a carboxylic acid group and a lactone ring present in terminal structures thereof, and a ratio (Y/Z) of a lactone ring content (Y) to a sum (Z) of a carboxylic acid content (X) and the lactone ring content (Y) is not less than 55% in a molar ratio.

An ethylene-vinyl alcohol copolymer resin composition comprising:

• an ethylene-vinyl alcohol copolymer;
• and
• from 5 ppm to 400 ppm of a boron compound on a boron basis based on the weight of the ethylene-vinyl alcohol copolymer resin composition;
• wherein the ethylene-vinyl alcohol copolymer comprises monomer units including at least an ethylene unit and a vinyl alcohol unit, and a carboxylic acid group and a lactone ring present in terminal structures thereof, and a ratio (Y/Z) of a lactone ring content (Y) to a sum (Z) of a carboxylic acid content (X) and the lactone ring content (Y) is not less than 55% in a molar ratio.

An ethylene-vinyl alcohol copolymer resin composition comprising:

• an ethylene-vinyl alcohol copolymer;
• and
• from 5 ppm to 800 ppm of a conjugated polyene compound based on the weight of the ethylene-vinyl alcohol copolymer resin composition,
• wherein the ethylene-vinyl alcohol copolymer comprises monomer units including at least an ethylene unit and a vinyl alcohol unit, and a carboxylic acid group and a lactone ring present in terminal structures thereof, and a ratio (Y/Z) of a lactone ring content (Y) to a sum (Z) of a carboxylic acid content (X) and the lactone ring content (Y) is not less than 55% in a molar ratio.