Multilayered container and method for producing same

Abstract

A multilayer container having a polyester layer comprising a thermoplastic polyester resin (X) and a polyamide layer comprising a polyamide resin (Y), wherein the polyester layer is an innermost layer and the polyamide layer is an interlayer, and the polyamide resin (Y) comprises a polyamide resin (Y-1) comprising a structural unit derived from a diamine and a structural unit derived from a dicarboxylic acid, 70 mol % or more of the structural unit derived from a diamine being a structural unit derived from xylylenediamine; and 70 mol % or more of the structural unit derived from a dicarboxylic acid being a structural unit derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and wherein a stretching ratio in a transverse direction (TD) is 2.2 times or more, and a stretching ratio in a machine direction (MD) to the stretching ratio in the transverse direction (TD) (MD/TD) is 0.6 or more and less than 1.0.

1 . A multilayer container comprising a polyester layer comprising a thermoplastic polyester resin (X) and a polyamide layer comprising a polyamide resin (Y),
 wherein the polyester layer is an innermost layer and the polyamide layer is an interlayer,   and the polyamide resin (Y) comprises a polyamide resin (Y-1) comprising a structural unit derived from a diamine and a structural unit derived from a dicarboxylic acid, 70 mol % or more of the structural unit derived from a diamine being a structural unit derived from xylylenediamine; and 70 mol % or more of the structural unit derived from a dicarboxylic acid being a structural unit derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and   wherein a stretching ratio in a transverse direction (TD) is 2.2 times or more, and a stretching ratio in a machine direction (MD) to the stretching ratio in the transverse direction (TD) (MD/TD) is 0.6 or more and less than 1.0.   
     
     
         2 . The multilayer container according to  claim 1 , wherein the multilayer container has a capacity of 200 to 600 mL. 
     
     
         3 . The multilayer container according to  claim 1 , wherein the multilayer container has a capacity of 200 to 350 mL. 
     
     
         4 . The multilayer container according to  claim 1 , wherein the multilayer container has a total thickness of 50 to 500 μm. 
     
     
         5 . The multilayer container according to  claim 1 , wherein the multilayer container comprises at least one polyester layer on the inside and the outside, respectively, of the polyamide layer. 
     
     
         6 . The multilayer container according to  claim 1 , wherein the multilayer container has a three-layer structure of a polyester layer as an innermost layer and an outermost layer and a polyamide layer as an interlayer. 
     
     
         7 . The multilayer container according to  claim 1 , wherein the thermoplastic polyester resin (X) comprises a thermoplastic polyester resin (X-1) comprising a structural unit derived from a dicarboxylic acid and a structural unit derived from a diol, 50 mol % or more of the structural unit derived from a dicarboxylic acid being a structural unit derived from terephthalic acid; and 50 mol % or more of the structural unit derived from a diol being a structural unit derived from ethylene glycol. 
     
     
         8 . The multilayer container according to  claim 7 , wherein the thermoplastic polyester resin (X-1) comprises a structural unit derived from a dicarboxylic acid and a structural unit derived from a diol, 90 mol % or more of the structural unit derived from a dicarboxylic acid being a structural unit derived from terephthalic acid; and 90 mol % or more of the structural unit derived from a diol being a structural unit derived from ethylene glycol. 
     
     
         9 . The multilayer container according to  claim 1 , wherein the polyamide resin (Y-1) comprises a structural unit derived from a diamine and a structural unit derived from a dicarboxylic acid, 80 mol % or more of the structural unit derived from a diamine being a structural unit derived from xylylenediamine; and 80 mol % or more of the structural unit derived from a dicarboxylic acid being a structural unit derived from adipic acid. 
     
     
         10 . A method for producing a multilayer container, comprising the following Steps 1 and 2:
 Step 1: a step for injection molding a multilayer preform comprising a polyester layer comprising a thermoplastic polyester resin (X) and a polyamide layer comprising a polyamide resin (Y),   wherein the polyester layer is an innermost layer and the polyamide layer is an interlayer, and   the polyamide resin (Y) comprises a polyamide resin (Y-1) comprising a structural unit derived from a diamine and a structural unit derived from a dicarboxylic acid, 70 mol % or more of the structural unit derived from a diamine being a structural unit derived from xylylenediamine; and 70 mol % or more of the structural unit derived from a dicarboxylic acid being a structural unit derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms;   Step 2: a step for biaxially stretch blow molding the multilayer preform obtained in the Step 1 by a process satisfying the following conditions (1) to (5):   (1) heating the surface of the multilayer preform at 80 to 120° C.; then   (2) blowing high pressure air while changing the pressure in multiple stages with stretching the multilayer preform in a mold in a machine direction using a rod;   (3) a pressure in a first stage at the time of blowing high pressure air in multiple stages (primary blow pressure) of 0.3 to 2.0 MPa;   (4) a delay time in primary blow of 0.1 to 0.5 seconds;   (5) a stretching ratio in a transverse direction (TD) of 2.2 times or more, and a stretching ratio in a machine direction (MD) to the stretching ratio in the transverse direction (TD) (MD/TD) of 0.6 or more and less than 1.0.   
     
     
         11 . The method for producing the multilayer container according to  claim 10 , wherein the polyamide layer of the multilayer preform has a moisture content of 0.005 to 1% by mass. 
     
     
         12 . The method for producing the multilayer container according to  claim 10 , wherein the multilayer container has a capacity of 200 to 350 mL.