GAS-BARRIER MATERIAL, METHOD OF PRODUCING THE SAME AND GAS-BARRIER PACKING MATERIAL
A gas-barrier material comprising a polycarboxylic acid polymer (A) and a compound (B) having two ring structures (b) each of which forming an ether bond to carbon that forms a double bond with nitrogen and containing oxygen in the ether bond, wherein a crosslinked structure is formed by the reaction of a carboxyl group in the polycarboxylic acid polymer (A) with one of the ring structures (b) of the compound (B). The gas-barrier material features excellent gas-barrier property, retort resistance and flexibility, can be cured at a low temperature within short periods of time, and can be excellently produced.
1 . A gas-barrier material comprising a polycarboxylic acid polymer (A) and a compound (B) having two ring structures each of which contains a double bond and an ether bond, the double bond being formed between a carbon atom and a nitrogen atom, the ether bond containing an oxygen atom and the carbon atom, wherein a crosslinked structure is formed by the reaction of a carboxyl group in said polycarboxylic acid polymer (A) with one of the ring structures.
2 . A gas-barrier material according to claim 1 , wherein at least one of the ring structures (b) contained in said compound (B) is an oxazoline group or a derivative thereof.
3 . A gas-barrier material according to claim 1 , wherein said compound (B) is a 2,2′-bis(2-oxazoline).
4 . A gas-barrier material according to claim 1 , wherein said polycarboxylic acid polymer (A) is a poly(meth)acrylic acid or a partly neutralized product thereof.
5 . A gas-barrier material according to claim 1 , wherein said compound (B) is contained in an amount of 2 to 60 parts by weight per 100 parts by weight of the polycarboxylic acid polymer (A).
6 . A gas-barrier material according to claim 1 , comprising the polycarboxylic acid polymer (A) and forming two amido ester bonds at the crosslinking portion.
7 . A gas-barrier material according to claim 1 , wherein metal ionic crosslinking is formed by polyvalent metal ions among the remaining unreacted carboxyl groups.
8 . A method of producing a gas-barrier material by forming a metal ionic crosslinking among the remaining unreacted carboxyl groups by treating the gas-barrier material of claim 1 with water containing a polyvalent metal compound.
9 . A method of producing a gas-barrier material of claim 1 by mixing together the polycarboxylic acid polymer (A) having a water content of not larger than 15% and the compound (B).
10 . A method of producing a gas-barrier material according to claim 9 , wherein a metal ionic crosslinking is formed among the remaining unreacted carboxyl groups by treating, with water containing a polyvalent metal compound, the gas-barrier material formed by mixing said polycarboxylic acid polymer (A) and the compound (B) together.
11 . A packing material having a layer of the gas-barrier material of claim 1 on the surface of a plastic base material or between the plastic layers.
12 . A packing material according to claim 11 , wherein the layer of said gas-barrier material is formed on the surface of a plastic base material via an anchoring layer, or at least one surface thereof is formed between the plastic layers via the anchoring layer.
13 . A packing material according to claim 12 , wherein said anchoring layer contains an urethane polymer.