Resin composition, molded object, modifier for polyamide resin, and method for modifying polyamide resin
The resin composition of the present disclosure contains a polyamide resin (A) and a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester, wherein the content of the modified ethylene-vinyl alcohol resin is 1 part by weight or more and less than 50 parts by weight, when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is taken as 100 parts by weight. This resin composition has excellent moldability and has excellent mechanical strength, in particular excellent tensile fracture strain properties, without impairing the transparency and solvent resistance of a molded object obtained from the resin composition.
1 . A resin composition consisting of: a polyamide resin (A); a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester; and other components,
wherein the content of the modified ethylene-vinyl alcohol resin (B) is 1 part by weight or more and less than 50 parts by weight, when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is taken as 100 parts by weight,
wherein the other components are present in an amount of 5 wt % or less of an entire resin composition, and
the other components comprise at least one selected from the group consisting of carboxylic-acid-modified polyolefin resin, a hydrocarbon resin with a number-average molecular weight of 100 to 3,000, and a softening point of 60° C. or more and less than 170° C., an antioxidant, a lubricant, an antistatic agent, a colorant, an ultraviolet absorber, a plasticizer, a thermal stabilizer, a light stabilizer, a surfactant, an antibacterial agent, a drying agent, an antiblocking agent, a flame retardant, a cross-linking agent, a curing agent, a foaming agent, a crystal nucleating agent, an antifogging agent, a biodegradable additive, and a silane coupling agent.
2 . The resin composition according to claim 1 , wherein the content of the modified ethylene-vinyl alcohol resin (B) is 1 to 45 parts by weight, when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is taken as 100 parts by weight.
3 . The resin composition according to claim 1 , wherein a modification rate of the modified ethylene-vinyl alcohol resin (B) is 0.1 mol % to 30 mol %.
4 . The resin composition according to claim 1 , wherein, in the modified ethylene-vinyl alcohol resin (B), the grafted aliphatic polyester is a ring-opening polymer of a lactone ring, and the number of carbon atoms constituting the lactone ring is 3 to 10.
5 . The resin composition according to claim 1 , wherein the total haze of a 30 μm-thick single-layer film obtained using the resin composition is 2% or less, as measured using a haze meter as defined in JIS K7105.
6 . A molded object made of the resin composition according to claim 1 .
7 . The molded object according to claim 6 , wherein the molded object is a sheet or a film.
8 . A method for modifying a polyamide resin (A) by blending only a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester; and other components into the polyamide resin (A), comprising:
setting the content of the modified ethylene-vinyl alcohol resin (B) to 1 part by weight or more and less than 50 parts by weight, when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is taken as 100 parts by weight; and
setting the content of the other components to 5 wt % or less of the total content of the polyamide resin (A), the modified ethylene-vinyl alcohol resin (B), and the other components, and
the other components comprise at least one selected from the group consisting of carboxylic-acid-modified polyolefin resin, a hydrocarbon resin with a number-average molecular weight of 100 to 3,000, and a softening point of 60° C. or more and less than 170° C., an antioxidant, a lubricant, an antistatic agent, a colorant, an ultraviolet absorber, a plasticizer, a thermal stabilizer, a light stabilizer, a surfactant, an antibacterial agent, a drying agent, an antiblocking agent, a flame retardant, a cross-linking agent, a curing agent, a foaming agent, a crystal nucleating agent, an antifogging agent, a biodegradable additive, and a silane coupling agent.
9 . The resin composition according to claim 1 , wherein a content of the modified ethylene-vinyl alcohol resin (B) is 1 to 10 parts by weight, when a total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is taken as 100 parts by weight.
10 . The resin composition according to claim 1 , wherein a number-average molecular weight of the modified ethylene-vinyl alcohol is 5,000 to 300,000.
11 . The resin composition according to claim 1 , wherein a number-average molecular weight of the modified ethylene-vinyl alcohol is 10,000 to 100,000.
12 . The resin composition according to claim 1 , wherein a glass transition temperature of the resin composition is lower than a glass transition temperature of the polyamide resin (A) by 3 to 50° C.
13 . The resin composition according to claim 1 , wherein a glass transition temperature of the resin composition is lower than a glass transition temperature of the polyamide resin (A) by 8 to 20° C.
14 . The resin composition according to claim 1 , wherein the other components includes carboxylic-acid-modified polyolefin resin (C).
15 . A resin composition consisting of: a polyamide resin (A); and a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester,
wherein the content of the modified ethylene-vinyl alcohol resin (B) is 1 part by weight or more and less than 50 parts by weight, when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is taken as 100 parts by weight.