Saponified ethylene-vinyl ester copolymer resin composition and multilayer structure using the composition
View Patent ↗Disclosed is an EVOH resin composition which exhibits coloration resistance and thermal resistance even at high temperature, and which has excellent adhesiveness to a thermoplastic resin composition. Such EVOH resin composition can provide a multilayer structure having excellent appearance. The EVOH resin composition comprises (A) an EVOH resin, (B) an alkaline earth metal, (C) an alkali metal, and (D) a carboxylic acid having from 2 to 4 carbon atoms, wherein the contents of the components (B), (C) and (D) are adjusted to the specific range.
1. A saponified ethylene-vinyl ester-based copolymer resin (EVOH resin) composition comprising
(A) a saponified ethylene-vinyl ester-based copolymer resin;
(B) an alkaline earth metal;
(C) an alkali metal; and
(D) a carboxylic acid having from 2 to 4 carbon atoms,
wherein the composition satisfies the following requirements (α), (β), and (γ):
(α) a content of the alkaline earth metal (B) is more than 10 ppm but not more than 50 ppm relative to the saponified ethylene-vinyl ester-based copolymer resin (A);
(β) a content ratio (C/B) of the alkali metal (C) to the alkaline earth metal (B) ranges from 0.001 to 0.5; and
(γ) a content ratio (D/B) of the carboxylic acid (D) to the alkaline earth metal (B) ranges from 5 to 30.
2. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , wherein a weight reduction of the composition after heating at 280° C. for 1 hour under a nitrogen atmosphere is not more than 15% by weight relative to the weight before heating.
3. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , wherein the alkaline earth metal (B) is magnesium.
4. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , wherein the carboxylic acid (D) is mono- or di-carboxylic acid having from 2 to 4 carbon atoms.
5. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , wherein the alkali metal (C) is potassium or sodium.
6. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , wherein a content of phosphate radical is not more than 5 ppm relative to the saponified ethylene-vinyl ester-based copolymer (A).
7. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , wherein the saponified ethylene-vinyl ester-based copolymer is a saponified ethylene-vinyl ester-based copolymers having 1,2-diol unit represented by the following formula,
wherein R 1 , R 2 , and R 3 each represents independently a hydrogen atom or an organic group, X represents single bond or a binding chain, R 4 , R 5 , and R 6 each represents independently a hydrogen atom or an organic group.
8. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 1 , further comprising (E) a basic amine compound.
9. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 8 , wherein the basic amine compound (E) is a basic amino acid.
10. The saponified ethylene-vinyl ester-based copolymer resin composition according to claim 8 , wherein a content of the basic amine compound (E) ranges from 0.01 to 10 parts by weight based on 100 parts by weight of EVOH resin.
11. A multilayer structure comprising at least one layer of a saponified ethylene-vinyl ester-based copolymer resin composition comprising
(A) a saponified ethylene-vinyl ester-based copolymer resin;
(B) an alkaline earth metal;
(C) an alkali metal; and
(D) a carboxylic acid having from 2 to 4 carbon atoms,
wherein the composition satisfies the following requirements (α), (β), and (γ):
(α) a content of the alkaline earth metal (B) is more than 10 ppm but not more than 50 ppm relative to the saponified ethylene-vinyl ester-based copolymer resin (A);
(β) a content ratio (C/B) of the alkali metal (C) to the alkaline earth metal (B) ranges from 0.001 to 0.5; and
(γ) a content ratio (D/B) of the carboxylic acid (D) to the alkaline earth metal (B) ranges from 5 to 30.
12. The multilayer structure according to claim 11 , wherein a layer of thermoplastic resin is laid on at least one of the saponified ethylene-vinyl ester-based copolymer resin composition layer.
13. The multilayer structure according to claim 12 , wherein the thermoplastic resin layer is polyester-based resin layer.
14. The multilayer structure according to claim 13 , comprising a structure unit of polyester-based resin layer/a saponified ethylene-vinyl ester-based copolymer resin composition layer/polyester-based resin layer.
15. A multilayer hollow container comprising a wall made of a multilayer structure comprising at least one layer of a saponified ethylene-vinyl ester-based copolymer resin composition comprising
(A) a saponified ethylene-vinyl ester-based copolymer resin;
(B) an alkaline earth metal;
(C) an alkali metal; and
(D) a carboxylic acid having from 2 to 4 carbon atoms,
wherein the composition satisfies the following requirements (α), (13), and (γ):
(α) a content of the alkaline earth metal (B) is more than 10 ppm but not more than 50 ppm relative to the saponified ethylene-vinyl ester-based copolymer resin (A);
(β) a content ratio (C/B) of the alkali metal (C) to the alkaline earth metal (B) ranges from 0.001 to 0.5; and
(γ) a content ratio (D/B) of the carboxylic acid (D) to the alkaline earth metal (B) ranges from 5 to 30.
16. The multilayer hollow container according to claim 15 , wherein the multilayer structure is a coinjection molded article.