Ethylene-vinyl alcohol copolymer composition pellet and process for producing said ethylene-vinyl alcohol copolymer composition pellet
The present invention provides ethylene-vinyl alcohol copolymer composition pellet reduced in coloration. The ethylene-vinyl alcohol copolymer composition pellet of the invention include an ethylene-vinyl alcohol copolymer (A), a polyamide resin (B), and an alkaline earth metal salt (C) and have a yellowness index (YI) value of 10 or less when examined with a spectral color-difference meter by a transmission method.
1. An ethylene-vinyl alcohol copolymer composition pellet comprising:
an ethylene-vinyl alcohol copolymer (A),
a polyamide resin (B) having a melting point of 180-270° C.,
an alkaline earth metal salt (C), the alkaline earth metal salt (C) including a salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms wherein a content of the salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, in terms of metal amount, is 10-50 ppm based on a sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B),
0% of any of an ethylene-unsaturated carboxylic acid random copolymer and a metal salt thereof, and
optionally, an antioxidant in an amount of 0.1-200 ppm per 100 parts by mass of the sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B);
wherein a yellowness index (YI) value obtained by measuring the pellet with a spectral color-difference meter by a transmission method is 10 or less.
2. The ethylene-ethylene-vinyl alcohol copolymer composition pellet according to claim 1 , wherein a mass ratio ((A)/(B)) of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B) is from 60/40 to 98/2.
3. The ethylene-vinyl alcohol copolymer composition pellet according to claim 1 , which comprises the antioxidant.
4. An ethylene-vinyl alcohol copolymer composition molding, which is obtained by melt-molding the ethylene-vinyl alcohol copolymer composition pellet according to claim 1 .
5. The ethylene-vinyl alcohol copolymer composition pellet according to claim 1 , wherein the ethylene-vinyl alcohol copolymer composition pellet is made by a process consisting of melt-kneading the ethylene-vinyl alcohol copolymer (A), the polyamide resin (B), the alkaline earth metal salt (C) and optionally the antioxidant, in a melt-kneading device, and discharging the ethylene-vinyl alcohol copolymer composition from the melt-kneading device such that the temperature of the ethylene-vinyl alcohol copolymer composition after being discharged is 268° C. or less, and then cutting the discharged ethylene-vinyl alcohol copolymer composition into pellets.
6. A process for producing ethylene-vinyl alcohol copolymer composition pellet having a yellowness index (YI) value, as measured with a spectral color-difference meter by a transmission method, of 10 or less, comprising:
melt-kneading a resin composition comprising
an ethylene-vinyl alcohol copolymer (A),
a polyamide resin (B) having a melting point of 180-270° C.,
an alkaline earth metal salt (C), the alkaline earth metal salt (C) including a salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, wherein a content of the salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, in terms of metal amount, is 10-50 ppm based on a sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B),
0% of any of an ethylene-unsaturated carboxylic acid random copolymer and a metal salt thereof, and
optionally, an antioxidant in an amount of 0.1-200 ppm per 100 parts by mass of the sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B)
using a melt-kneading device,
wherein a temperature of an ethylene-vinyl alcohol copolymer composition strand just after being discharged from the melt-kneading device is 268° C. or lower.
7. The process of claim 6 , wherein a temperature of the ethylene-vinyl alcohol copolymer composition strand just after being discharged from the melt-kneading device is higher by 5-48° C. than the melting point of the polyamide resin (B).
8. An ethylene-vinyl alcohol copolymer composition pellet comprising:
an ethylene-vinyl alcohol copolymer (A),
a polyamide resin (B) having a melting point of 180-270° C.,
an alkaline earth metal salt (C), the alkaline earth metal salt (C) including a salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, wherein a content of the salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, in terms of metal amount, is 10-50 ppm based on a sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B),
0% of a thermoplastic resin other than the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B), and
optionally, an antioxidant in an amount of 0.1-200 ppm per 100 parts by mass of the sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B);
wherein a yellowness index (YI) value obtained by measuring the pellet with a spectral color-difference meter by a transmission method is 10 or less.
9. The ethylene-ethylene-vinyl alcohol copolymer composition pellet according to claim 8 , wherein a mass ratio ((A)/(B)) of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B) is from 60/40 to 98/2.
10. The ethylene-vinyl alcohol copolymer composition pellet according to claim 8 , which comprises the antioxidant.
11. An ethylene-vinyl alcohol copolymer composition molding, which is obtained by melt-molding the ethylene-vinyl alcohol copolymer composition pellet according to claim 8 .
12. The ethylene-vinyl alcohol copolymer composition pellet according to claim 8 , wherein the ethylene-vinyl alcohol copolymer composition pellet is made by a process consisting of melt-kneading the ethylene-vinyl alcohol copolymer (A), the polyamide resin (B), the alkaline earth metal salt (C) and optionally the antioxidant, in a melt-kneading device, and discharging the ethylene-vinyl alcohol copolymer composition from the melt-kneading device such that the temperature of the ethylene-vinyl alcohol copolymer composition after being discharged is 268° C. or less, and then cutting the discharged ethylene-vinyl alcohol copolymer composition into pellets.
13. A process for producing ethylene-vinyl alcohol copolymer composition pellet having a yellowness index (YI) value, as measured with a spectral color-difference meter by a transmission method, of 10 or less, comprising:
melt-kneading a resin composition comprising
an ethylene-vinyl alcohol copolymer (A),
a polyamide resin (B) having a melting point of 180-270° C.,
an alkaline earth metal salt (C), the alkaline earth metal salt (C) including a salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, wherein a content of the salt of magnesium with an aliphatic carboxylic acid having 1-6 carbon atoms, in terms of metal amount, is 10-50 ppm based on a sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B),
0% of a thermoplastic resin other than the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B), and
optionally, an antioxidant in an amount of 0.1-200 ppm per 100 parts by mass of the sum of the ethylene-vinyl alcohol copolymer (A) and the polyamide resin (B)
using a melt-kneading device,
wherein a temperature of an ethylene-vinyl alcohol copolymer composition strand just after being discharged from the melt-kneading device is 268° C. or lower.
14. The process of claim 13 , wherein a temperature of the ethylene-vinyl alcohol copolymer composition strand just after being discharged from the melt-kneading device is higher by 5-48° C. than the melting point of the polyamide resin (B).
15. The ethylene-vinyl alcohol copolymer composition pellet according to claim 3 , wherein the antioxidant is a phenolic antioxidant.
16. The ethylene-vinyl alcohol copolymer composition pellet according to claim 15 , wherein the antioxidant is a hindered phenolic antioxidant.