Methods for producing resin film and layered article

A method for producing a layered structure comprising a resin film and a substrate having thereon the resin film, comprising:

• applying a liquid to a substrate, the liquid having been prepared by dispersing a resin composition (C) which comprises a resin component (A) with hydroxyl groups and carboxyl groups and alkali metal ions (B) comprising at least one species selected from a sodium ion, and a lithium ion, and satisfies conditions (1) and (2) given below, the resin composition further comprising clay minerals, in a solvent,
• removing the solvent from the applied liquid to form a precursor film (D′) on the substrate, and
• subjecting the precursor film (D′) to the following treatments together with the substrate:
• dry heating treatment comprising holding the precursor film under an atmosphere characterized by a temperature not lower than 100° C. and a water vapor concentration less than 50 g/m3,
• wet heating treatment comprising holding the precursor film resulting from the dry heating treatment under an atmosphere characterized by a temperature not lower than 100° C. and a water vapor concentration more than 290 g/m3, and
• drying the precursor film resulting from the wet heating treatment:
• condition (1):
• the ratio of the number of the hydroxyl groups to the number of the carboxyl groups in the resin component (A) is from 30:70 to 95:5 (hydroxyl groups:
• carboxyl groups),
• condition (2):
• the weight of the alkali metal ions (B) contained in the resin composition (C) is from 0.2% to 5% of the weight of the resin component (A), wherein the resin component (A) comprises a resin component (A2) comprising at least one species selected from polyvinyl alcohols, and polysaccharides, having hydroxyl groups and a resin component (A3) comprising at least one species selected from polyacrylic acid, polymethacrylic acid, partially neutralized polyacrylic acid, and partially neutralized polymethacrylic acid;
• and wherein the clay minerals are a montmorillonite.