Aqueous resin composition having gas barrier properties and laminated film using the same

1. An aqueous resin composition having gas barrier properties, which comprises

(i) a polyurethane resin having a urethane group and a urea group in a total concentration of 25 to 60% by weight and having an acid group,

(ii) an inorganic compound, and

(iii) a polyamine,

wherein the polyurethane resin (i) is an aqueous polyurethane resin which comprises a residue of a polyisocyanate compound (A), a residue of a polyhydroxyalkanecarboxylic acid (B), and optionally a polyol compound (C), wherein when the polyol compound (C) is included, each of the residues (B) and (C) are bonded to the residue of the polyisocyanate compound (A) through a urethane group for forming a prepolymer having an isocyanate group and a carboxyl group, and a residue of a chain-extension agent (D) which bonds to the prepolymer through at least a urea group to form a polyurethane having the carboxyl group, and the carboxylic group of the polyurethane is neutralized with a neutralizing agent, and the chain-extension agent (D) is at least one member selected from the group consisting of a diamine, hydrazine and a hydrazine derivative; the proportion of the total amount of components (B), (C) and (D) each having an active hydrogen atom is, as the total amount of the active hydrogen atom, about 0.8 to 1.2 mol relative to 1 mol of the isocyanate group of the polyisocyanate compound (A); and the polyisocyanate compound (A) contains at least one member selected from the group consisting of a xylylene diisocyanate and a hydrogenated xylylene diisocyanate;

the inorganic compound (ii) consists essentially of at least one swelling inorganic layered compound selected from the group consisting of a smectite group clay mineral and a mica group clay mineral;

the polyamine (iii) comprises urethane-modified polyamine; the polyamine (iii) is a component added to a dispersion of the at least one swelling inorganic layered compound (ii), an aqueous solution or dispersion of the polyurethane resin (i), or a dispersion containing an aqueous solution or dispersion of the polyurethane resin (i) and the at least one swelling inorganic layered compound (ii); and

the proportion of the acid group of the polyurethane resin (i) relative to the basic nitrogen atom of the polyamine (iii) is 3/1 to 1/2 as the equivalent ratio.

2. A resin composition according to claim 1 , wherein the polyurethane resin (i) comprises the residue of the polyisocyanate compound (A), the residue of the polyhydroxyalkanecarboxylic acid (B), and a residue of a polyol compound (C), each of the residues (B) and (C) bonding to the residue of the polyisocyanate compound (A) through a urethane group for forming a prepolymer having an isocyanate group, and a carboxyl group, and the residue of the chain-extension agent (D) which bonds to the prepolymer through at least a urea group to form a polyurethane having the carboxyl group, and the carboxylic group of the polyurethane is neutralized with a neutralizing agent;

the polyisocyanate compound (A) contains at least one member selected from the group consisting of a xylylene diisocyanate and a hydrogenated xylylene diisocyanate; and

the polyol compound (C) contains a polyol component having 2 to 8 carbon atoms in a proportion of not less than 90% by weight in the polyol compound.

3. A resin composition according to claim 1 , wherein the at least one swelling inorganic layered compound (ii) comprises at least one member selected from the group consisting of a water-swelling mica and a montmorillonite.

4. A resin composition according to claim 1 , wherein the acid value of the polyurethane resin (i) is 16 to 50 mgKOH/g, and the amine value of the polyamine (iii) is 300 to 1500 mgKOH/g.

5. A resin composition according to claim 1 , wherein the ratio of the at least one swelling inorganic layered compound (ii) relative to the polyurethane resin (i) is 1/100 to 200/100 in terms of solid content.

6. A gas barrier laminated film comprising a base film, and a layer formed on at least one surface of the base film, wherein the layer comprises the aqueous resin composition recited in claim 1 .

7. A gas barrier laminated film comprising a base film, and a layer formed on at least one surface of the base film, wherein the layer comprises the aqueous resin composition recited in claim 2 .

8. A gas barrier laminated film comprising a base film, and a layer formed on at least one surface of the base film, wherein the layer comprises the aqueous resin composition recited in claim 3 .

9. A gas barrier laminated film comprising a base film, and a layer formed on at least one surface of the base film, wherein the layer comprises the aqueous resin composition recited in claim 4 .

10. A gas barrier laminated film comprising a base film, and a layer formed on at least one surface of the base film, wherein the layer comprises the aqueous resin composition recited in claim 5 .

11. An aqueous resin composition having gas barrier properties, which comprises

(i) a polyurethane resin having a urethane group and a urea group in a total concentration of 25 to 60% by weight and having an acid group,

(ii) an inorganic compound, and

(iii) a polyamine,

wherein the polyurethane resin (i) is an aqueous polyurethane resin which comprises a residue of a polyisocyanate compound (A), a residue of a polyhydroxyalkanecarboxylic acid (B), and optionally a polyol compound (C), wherein when the polyol compound (C) is included, each of the residues (B) and (C) are bonded to the residue of the polyisocyanate compound (A) through a urethane group for forming a prepolymer having an isocyanate group and a carboxyl group, and a residue of a chain-extension agent (D) which bonds to the prepolymer through at least a urea group to form a polyurethane having the carboxyl group, and the carboxylic group of the polyurethane is neutralized with a neutralizing agent, and the chain-extension agent (D) is at least one member selected from the group consisting of a diamine, hydrazine and a hydrazine derivative, the proportion of the total amount of components (B), (C) and (D) each having an active hydrogen atom is, as the total amount of the active hydrogen atom, about 0.8 to 1.2 mol relative to 1 mol of the isocyanate group of the polyisocyanate compound (A); and the polyisocyanate compound (A) contains at least one member selected from the group consisting of a xylylene diisocyanate and a hydrogenated xylylene diisocyanate;

the inorganic compound (II) consists essentially of at least one swelling inorganic layered compound selected from the group consisting of a smectite group clay mineral and a mica group clay mineral;

the polyamine (iii) comprises a urethane-modified polyamine; the polyamine (iii) is a component added to a dispersion of the at least one swelling inorganic layered compound (ii), an aqueous solution or dispersion of the polyurethane resin (i), or a dispersion containing an aqueous solution or dispersion of the polyurethane resin (i) and the at least one swelling inorganic layered compound (ii);

the proportion of the acid group of the polyurethane resin (i) relative to the basic nitrogen atom of the polyamine (iii) is 3/1 to 1/2 as an equivalent ratio, and

the acid value of the polyurethane resin (i) is 15 to 60 mgKOH/g, and the amine value of the polyamine (iii) is 200 to 1700 mgKOH/g.

12. A resin composition according to claim 11 , wherein the polyurethane resin (i) comprises the residue of the polyisocyanate compound (A), the residue of the polyhydroxyalkanecarboxylic acid (B), and a residue of a polyol compound (C), each of the residues (B) and (C) bonding to the residue of the polyisocyanate compound (A) through a urethane group for forming a prepolymer having an isocyanate group and a carboxyl group, and the residue of the chain-extension agent (D) which bonds to the prepolymer through at least a urea group to form a polyurethane having the carboxyl group, and the carboxylic group of the polyurethane is neutralized with a neutralizing agent;

the polyisocyanate compound (A) contains at least one member selected from the group consisting of a xylylene diisocyanate and a hydrogenated xylylene diisocyanate in a proportion of not less than 30% by weight in the polyisocyanate compound; and

the polyol compound (C) contains a polyol component having 2 to 8 carbon atoms in a proportion of not less than 90% by weight in the polyol compound.

13. A resin composition according to claim 11 , wherein the at least one swelling inorganic layered compound (ii) comprises at least one member selected from the group consisting of a water-swelling mica and a montmorillonite.

14. A resin composition according to claim 11 , wherein the ratio of the at least one swelling inorganic layered compound (ii) relative to the polyurethane resin (i) is 1/100 to 200/100 in terms of solid content.

15. A gas barrier laminated film comprising a base film, and a layer formed on at least one surface of the base film, wherein the layer comprises the aqueous resin composition recited in claim 11 .

16. A resin composition according to claim 1 , wherein said polyamine is interposed between layers of the at least one inorganic layered compound (ii).