Method of producing gas-barrier laminated member
A method of producing a gas-barrier laminated member having a gas-barrier layer formed by crosslinking the carboxyl groups of a polycarboxylic acid polymer with multivalent metal ions. The method comprises forming a layer (A) containing an alkaline compound of a multivalent metal on at least one surface of a plastic base material, applying a solution (b) obtained by dissolving a polycarboxylic acid polymer in a solvent containing at least water onto the layer (A) that contains the alkaline compound of the multivalent metal, and removing the solvent by a heat treatment so that a metal-ionically crosslinked structure is formed with the multivalent metal ions among the carboxyl groups in the solution (b). The gas-barrier laminated member has excellent adhesion to the base material, gas-barrier property, retort resistance and flexibility, and is efficiently produced by only being heated at a low temperature for a short period of time through a decreased number of simplified steps.
1. A method of producing a gas-barrier laminated member comprising
forming, on at least one surface of a plastic base material, a layer (A) comprising a coating composition (a) that contains
an alkaline compound of a multivalent metal,
an isocyanate compound and
a resin component in an amount of 15 to 80% by weight with respect to the solid component, the resin component containing a polyester polyol having a resin skeleton with no monovalent metal element;
and thereafter,
applying onto the layer (A) a solution (b) obtained by dissolving a polycarboxylic acid polymer in a solvent containing at least water and containing a crosslinking agent capable of forming a crosslinked structure due to covalent bonds between carboxyl groups unreacted with the multivalent metal ion, and removing the solvent by a heat treatment so that a metal-ionically crosslinked structure due to the multivalent metal ions and a crosslinked structure due to the covalent bonds are formed among the carboxyl groups in the solution (b).
2. The method of producing a gas-barrier laminated member according to claim 1 , wherein a urethane bond is formed in said layer (A).
3. The method of producing a gas-barrier laminated member according to claim 1 , wherein said solution (b) contains a solvent having good affinity to the layer that contains the alkaline compound of the multivalent metal.
4. The method of producing a gas-barrier laminated member according to claim 1 , wherein said polycarboxylic acid polymer is a poly(meth)acrylic acid or a partly neutralized product thereof.
5. The method of producing a gas-barrier laminated member according to claim 1 , wherein the primary particle size of the alkaline compound of the multivalent metal is not larger than 0.5 μm.
6. The method of producing a gas-barrier laminated member according to claim 1 , wherein said alkaline compound of the multivalent metal comprises at least one of a carbonate or a hydroxide of calcium or magnesium.
7. The method of producing a gas-barrier laminated member according to claim 1 , wherein said cross-linked portion is forming at least two ester bonds or amido ester bonds.
8. The method of producing a gas-barrier laminated member according to claim 1 , wherein said cross-linked portion is forming at least one ester bond neighboring the cycloalkyl group.
9. The gas-barrier laminated member produced by the production method of claim 1 .