Biaxially oriented polyester film and laminated body

Patent metadata

Field	Value
Publication number	US-12215255-B2
Application number	US-202118247974-A
Country	US
Kind code	B2
Filing date	Oct 4, 2021
Priority date	Oct 7, 2020
Publication date	Feb 4, 2025
Grant date	Feb 4, 2025

Abstract

Disclosed is a biaxially oriented polyester film that is excellent in adhesiveness with a metal layer etc., and excellent in deep drawability for an isotropic shape, such as a square shape. A biaxially oriented polyester film having at least a base layer and an adhesive layer each of which contains a polyester as a main component, the film satisfying the following requirements (1) to (3): (1) a difference between reversible heat capacity difference (ΔCp) at around glass transition temperatures of the adhesive layer and the base layer is not smaller than 0.10 and not larger than 0.45; (2) a molecular orientation ratio measured by using a molecular orientation meter is higher than 1.2; and (3) a stress at 10% elongation (F10) in each of a machine and transverse direction is not lower than 90 MPa and not higher than 160 MPa.

First claim

The invention claimed is:

1. A biaxially oriented polyester film, comprising at least a base layer and an adhesive layer each of which contains a polyester as a main component, wherein
the biaxially oriented polyester film satisfies the following requirements (1) to (3):
(1) a difference between reversible heat capacity differences (ΔCp) at around glass transition temperatures of the adhesive layer and the base layer is not smaller than 0.10 and not larger than 0.45;
(2) the biaxially oriented polyester film has a molecular orientation ratio measured by using a molecular orientation meter, the molecular orientation ratio being higher than 1.2; and
(3) the biaxially oriented polyester film has a stress at 10% elongation (F10) in each of a machine direction and a transverse direction, the stress at 10% elongation (F10) being not lower than 90 MPa and not higher than 160 MPa.

2. The biaxially oriented polyester film according to claim 1 , wherein the base layer contains polyethylene terephthalate in an amount of not lower than 60% by mass with respect to 100% by mass of a resin composition forming the base layer.

3. The biaxially oriented polyester film according to claim 2 , wherein the base layer contains polyethylene terephthalate in an amount of not lower than 60% by mass and not higher than 90% by mass with respect to 100% by mass of the resin composition forming the base layer and contains polybutylene terephthalate in an amount of not lower than 10% by mass and not higher than 40% by mass with respect to 100% by mass of the resin composition forming the base layer.

4. The biaxially oriented polyester film according to claim 1 , wherein
the adhesive layer contains a polyethylene terephthalate resin obtained by copolymerization,
an ethylene terephthalate unit content with respect to the polyester contained in the adhesive layer is not lower than 75% by mole and not higher than 95% by mole, and
a copolymerization component content with respect to the polyester contained in the adhesin layer is not lower than 5% by mole and not higher than 25% by mole.

5. A laminated body, comprising the biaxially oriented polyester film according to claim 1 and a metal layer laminated on the adhesive layer side of the biaxially oriented polyester film.

6. The laminated body according to claim 5 , wherein the metal layer is an aluminum layer having a thickness of not smaller than 15 μm and not larger than 80 μm.

7. A packaging material in which the laminated body according to claim 6 is used.

Assignees

• Toyo Boseki

Inventors

• TAMARI Noboru
• Haruta Masayuki

Classifications

• C09J2400/163

  in the substrate · CPC title

• C09J167/03

  the dicarboxylic acids and dihydroxy compounds having the carboxyl - and the hydroxy groups directly linked to aromatic rings · CPC title

• B65D65/40

  Applications of laminates for particular packaging purposes {(B65D1/0215, B65D1/28, B65D3/22, B65D5/0281, B65D5/563, B65D9/30, B65D29/02, B65D31/02, B65D75/26, B65D77/2024, B65D81/1275, B65D81/3811, B65D81/3823, B65D81/3834, B65D81/3846, B65D81/3858, B65D81/3874, B65D81/3886, B65D81/3897 take precedence; laminates per se or laminated packages characterised by the composition or)} · CPC title

• C09J2301/414

  presence of a copolymer · CPC title

• C09J2301/312

  parameters being the characterizing feature · CPC title