Copolyester, polyester composition containing the copolyester, and polyester laminated structure having layer composed of the copolyester or the polyester composition

A film composed of a polyester composition comprising (A) 50 to 95% by weight of polyethylene terephthalate and (B) 50 to 5% by weight of a copolyester having an intrinsic viscosity, measured in o-chlorophenol at 25.degree. C., of 0.3 to 1.5 dl/g and being derived from dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units.

A preform composed of a polyester composition comprising (A) 50 to 95% by weight of polyethylene terephthalate and (B) 50 to 5% by weight of a copolyester having an intrinsic viscosity, measured in o-chlorophenol at 25.degree. C., of 0.3 to 1.5 dl/g and being derived from dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units.

A container composed of a polyester composition comprising (A) 50 to 95% by weight of polyethylene terephthalate and (B) 50 to 5% by weight of a copolyester having an intrinsic viscosity, measured in o-chlorophenol at 25.degree. C., of 0.3 to 1.5 dl/g and being derived from dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units.

A polyester laminated structure composed of (C) a polyalkylene terephthalate layer and (D) a copolyester layer, the copolyester layer (D) being composed of a copolyester derived from dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units, or a copolyester composition comprising said copolyester and polyethylene terephthalate.

A stretched polyester laminated structure composed of (C) a polyalkylene terephthalate layer and (D) a copolyester layer composed of a copolyester derived from a dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units or a copolyester composition comprising said copolyester and polyethylene terephthalate, said polyalkylene terephthalate layer (C) and the copolyester layer (D) being stretched.

A preform for a laminated blow-molded article, said preform being composed of (C) a polyalkylene terephthalate layer and (D) a copolyester layer, the copolyester layer (D) being composed of a copolyester derived from dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units, or a copolyester composition comprising said copolyester and polyethylene terephthalate.

A polyester laminated blow-molded article composed of (C) a polyalkylene terephthalate layer and (D) a copolyester layer, the copolyester layer (D) being composed of a copolyester derived from dicarboxylic acid units composed of 95 to 60 mole % of isophthalic acid units and 5 to 40 mole % of 2,6-naphthalenedicarboxylic acid units and dihydroxy compound units composed of 95 to 70 mole % of ethylene glycol units and 5 to 30 mole % of 1,3-bis(2-hydroxyethoxy)benzene units, or a copolyester composition comprising said copolyester and polyethylene terephthalate.