Method for producing resin film and layered article

Abstract

Methods for producing a resin film or a layered article which are excellent in gas barrier properties under high humidity conditions are disclosed. In the methods, a precursor film of a resin composition composed of alkali metal ions and a resin component having both hydroxyl groups and carboxyl groups is subjected to treatments including (i) dry heating treatment of 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/m 3 , (ii) wet heating treatment of 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/m 3 or in water at a temperature not lower than 80° C., and (iii) drying the precursor film resulting from the wet heating treatment.

1 . A method for producing a resin film, comprising subjecting a precursor film (D) made of a resin composition (C) which comprises a resin component (A) with hydroxyl groups and carboxyl groups and alkali metal ions (B) and satisfies conditions (1) and (2) given below to the following treatments: 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/m 3 , 
 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/m 3  or in water at a temperature not lower than 80° C., 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).    
   
   
       2 . The method according to  claim 1 , wherein the combined weight of the hydroxyl groups and the carboxyl groups in the resin component (A) is from 30% to 60% of the weight of the resin component (A).  
   
   
       3 . The method according to  claim 1 , wherein the resin component (A) is a resin component (A1) having both hydroxyl groups and carboxyl groups in one molecule.  
   
   
       4 . The method according to  claim 1 , wherein the resin component (A) comprises a resin component (A2) having hydroxyl groups and a resin component (A3) having carboxyl groups.  
   
   
       5 . The method according to  claim 3 , wherein the resin component (A1) is a vinyl alcohol-acrylic acid copolymer or a vinyl alcohol-methacrylic acid copolymer.  
   
   
       6 . The method according to  claim 4 , wherein the resin component (A2) is a polyvinyl alcohol.  
   
   
       7 . The method according to  claim 4 , wherein the resin component (A3) comprises at least one species selected from polyacrylic acid, polymethacrylic acid, partially neutralized polyacrylic acid and partially neutralized polymethacrylic acid.  
   
   
       8 . The method according to  claim 1 , wherein the alkali metal ions (B) are sodium ions.  
   
   
       9 . 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) and satisfies conditions (1) and (2) given below 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/m 3 ,    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/m 3  or in water at a temperature not lower than 80° C., 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).    
   
   
       10 . The method according to  claim 9 , wherein the combined weight of the hydroxyl groups and the carboxyl groups in the resin component (A) is from 30% to 60% of the weight of the resin component (A).  
   
   
       11 . The method according to  claim 9 , wherein the resin component (A) is a resin component (A1) having both hydroxyl groups and carboxyl groups in one molecule.  
   
   
       12 . The method according to  claim 9 , wherein the resin component (A) comprises a resin component (A2) having hydroxyl groups and a resin component (A3) having carboxyl groups.  
   
   
       13 . The method according to  claim 11 , wherein the resin component (A1) is a vinyl alcohol-acrylic acid copolymer or a vinyl alcohol-methacrylic acid copolymer.  
   
   
       14 . The method according to  claim 12 , wherein the resin component (A2) is a polyvinyl alcohol.  
   
   
       15 . The method according to  claim 12 , wherein the resin component (A3) comprises at least one species selected from polyacrylic acid, polymethacrylic acid, partially neutralized polyacrylic acid and partially neutralized polymethacrylic acid.  
   
   
       16 . The method according to  claim 9 , wherein the alkali metal ions (B) are sodium ions.