Multilayer structure, packaging material in which same is utilized, regrind composition, and method for producing regrind composition

A multilayer structure comprising:

• a polyolefin layer (A);
• an adhesive resin layer (B);
• and
• a resin composition layer (C),
• wherein
• the polyolefin layer (A) is laminated on at least one face of the resin composition layer (C) via the adhesive resin layer (B),
• the multilayer structure comprises neither a layer in which a resin having a melting point of 210° C. or higher is a principal component, nor a metal layer having a thickness of 1 μm or more,
• a resin being a principal component constituting the polyolefin layer (A) comprises a polyolefin resin having a density of 0.850 g/cm3 or more and 0.940 g/cm3 or less,
• the resin composition layer (C) comprises an ethylene-vinyl alcohol copolymer (c1) and a polyvalent metal ion (c2),
• an ethylene unit content in the ethylene-vinyl alcohol copolymer (c1) is 20 mol % or more and 50 mol % or less, and a degree of saponification of the ethylene-vinyl alcohol copolymer (c1) is 90 mol % or more,
• a content of the polyvalent metal ion (c2) in the resin composition layer (C) is 10 ppm or more and 400 ppm or less,
• the polyvalent metal ion (c2) comprises at least one selected from the group consisting of a magnesium ion, a calcium ion, a zinc ion, a cobalt ion, and a manganese ion, and
• the multilayer structure is in a film form which has a lengthwise direction and a crosswise direction, and
• of a cross section in the crosswise direction, provided that a site at one end of the crosswise direction is defined as 0% and a site at an other end of the crosswise direction is defined as 100%, a ratio (Cmin/Cmax) of a minimum value Cmin of a thickness of the resin composition layer (C) to a maximum value Cmax of the thickness, observed in an area of 45% to 55%, is 0.70 or more.