Multilayer structure and method for producing same

A retort processed package, comprising:

• a multilayer container and a content in the container,
• the multilayer container comprising:
• a layer of a resin composition (A);
• a layer of a saponified ethylene-vinyl acetate copolymer (B) having an ethylene content of from 20 to 65 mol % and having a degree of saponification of vinyl acetate units of 96% or more;
• and
• a layer of polyolefin (C) on a side of the layer of a resin composition (A) and the layer of a saponified ethylene-vinyl acetate copolymer (B),
• wherein
• the container comprises two of the layers of the resin composition (A), and the layer of the saponified ethylene-vinyl acetate copolymer (B) is between the layers of the resin composition (A),
• the resin composition (A) comprises a polyolefin (D), a saponified ethylene-vinyl acetate copolymer (E) having an ethylene content of from 20 to 65 mol % and having a degree of saponification of vinyl acetate units of 96% or more, and from 0.3 to 2.0 mass % of the resin composition (A) of at least one copolymer (F) selected from the group consisting of a saponified ethylene-vinyl acetate copolymer (F1) having an ethylene content of from 68 to 98 mol % and having a degree of saponification of vinyl acetate units of 20% or more and an acid-modified ethylene-vinyl acetate copolymer (F2) having an ethylene content of from 68 to 98 mol %,
• a mass ratio (E/F) of the saponified ethylene-vinyl acetate copolymer (E) to a total of the copolymer (F) is from 0.05 to 30,
• the saponified ethylene-vinyl acetate copolymer (E) is dispersed as particles with an average particle diameter of from 0.1 to 1.8 μm in a matrix of the resin composition polyolefin (D),
• the layer of the resin composition (A) has a thickness of from 50 to 1000 μm,
• the layer of the polyolefin (C) has a thickness of from 25 to 1000 μm, and
• the container has an oxygen transmission rate after 24 hours passed since retort processed for 30 minutes at 120° C. and 0.15 MPa of from 0.1 to 6 cc/m2·day·atm.