Resin composition and multilayer structure using same
A resin composition which can suppress the deterioration of performances of a multilayer structure due to moisture absorption regardless that the multilayer structure includes a hygroscopic layer whose performance is deteriorated due to moisture absorption, and a multilayer structure including a layer of the resin composition, are provided. Since the resin composition contains a hydrate-forming alkaline earth metal salt having a specific water absorption property, a multilayer structure comprising a layer of the resin composition can exhibit moisture resistance as a whole of the multilayer structure without affecting the appearance thereof.
1. A resin composition comprising:
(A) a base resin consisting of a thermoplastic resin other than a saponified ethylene-vinyl ester-based copolymer; and
(B) a hydrate-forming alkaline earth metal salt satisfying the water absorption properties shown below:
(α) a ratio of X 5: Y from 0.2:1 to 2.0:1, wherein X 5 is an amount of water absorption for 5 days per 100g of the alkaline earth metal salt (B) when being placed for 5 days under a condition of 40° C. and 90% relative humidity, and Y is a content of crystallization water in maximum hydrate of the alkaline earth metal salt (B); and
(γ) a local maximum point exists in the amount of water absorption when the hydrate-forming alkaline earth metal salt (B) is placed under the condition of 40° C. and 90% relative humidity.
2. The resin composition according to claim 1 , wherein the hydrate-forming alkaline earth metal salt (B) satisfies water absorption property (β) shown below:
(β) an amount of water absorption (Z) per 100 g of the alkaline earth metal salt (B) when being placed for 24 hours under the condition of 40° C. and 90% relative humidity is at least 10 g.
3. The resin composition according to claim 1 , wherein the alkaline earth metal salt (B) is a salt of an acid selected from at least one of the group consisting of lactic acid, silicic acid, phosphoric acid, and citric acid, and the alkaline earth metal salt is completely dehydrated or partially dehydrated up to the water content of 50% by weight or less, or a combination thereof.
4. The resin composition according to claim 1 wherein a weight ratio (A:B) of the base resin (A) to the hydrate-forming alkaline earth metal salt (B) is from more than 50:50 to 99:1.
5. The resin composition according to claim 1 , wherein the base resin (A) is a polyamide-based resin or an olefin-based resin.
6. The resin composition according to claim 1 , wherein the base resin (A) is a polar group-modified polymer.
7. A multilayer structure comprising at least one layer of a resin composition comprising:
(A) a base resin consisting of a thermoplastic resin other than a saponified ethylene-vinyl ester-based copolymer; and
(B) a hydrate-forming alkaline earth metal salt satisfying the water absorption properties shown below:
(α) a ratio of X 5 :Y from 0.2:1 to 2.0:1, wherein X 5 is an amount of water absorption for 5 days per 100 g of the alkaline earth metal salt (B) when being placed for 5 days under a condition of 40° C. and 90% relative humidity, and Y is a content of crystallization water in maximum hydrate of the alkaline earth metal salt (B); and
(γ) a local maximum point exists in the amount of water absorption when the hydrate-forming alkaline earth metal salt (B) is placed under the condition of 40° C. and 90% relative humidity.
8. A multilayer structure according to claim 7 , further comprising a layer of a thermoplastic resin not containing a hydrate-forming alkaline earth metal salt (B) or a composition thereof.
9. A multilayer structure comprising a layer unit in which a layer of a thermoplastic resin not containing hydrate-forming alkaline earth metal salt (B) or a composition thereof is arranged adjacent to the layer of a resin composition comprising:
(A) a base resin consisting of a thermoplastic resin other than a saponified ethylene-vinyl ester-based copolymer; and
(B) a hydrate-forming alkaline earth metal salt satisfying the water absorption properties shown below:
(α) a ratio of X 5 :Y from 0.2:1 to 2.0:1, wherein X 5 is an amount of water absorption for 5 days per 100 g of the alkaline earth metal salt (B) when being placed for 5 days under a condition of 40° C. and 90% relative humidity, and Y is a content of crystallization water in maximum hydrate of the alkaline earth metal salt (B); and
(γ) a local maximum point exists in the amount of water absorption when the hydrate-forming alkaline earth metal salt (B) is placed under the condition of 40° C. and 90% relative humidity.
10. The multilayer structure according to claim 8 , wherein the thermoplastic resin has 100 mL·20 μm/(m 2 ·day·atm) or less of oxygen permeability at 20° C. and 65% relative humidity measured by an isopiestic method in accordance with JIS-K7126.
11. The multilayer structure according to claim 9 , wherein the thermoplastic resin has 100 mL·20 μm/(m 2 ·day·atm) or less of oxygen permeability at 20° C. and 65% relative humidity measured by an isopiestic method in accordance with JIS-K7126.
12. The multilayer structure according to claim 8 , wherein the thermoplastic resin is a saponified ethylene-vinyl ester-based copolymer.
13. The multilayer structure according to claim 9 , wherein the thermoplastic resin is a saponified ethylene-vinyl ester-based copolymer.
14. The multilayer structure according to claim 7 , wherein the base resin (A) in the resin composition is a hydrophobic resin.
15. The multilayer structure according to claim 7 , wherein the base resin (A) in the resin composition is a polar group-modified polymer.