Heat-shrinkable polyester film and package

• US 10,035,335 B2
• Filed: 03/03/2015
• Issued: 07/31/2018
• Est. Priority Date: 04/01/2014
• Status: Active Grant

• Current Assignee: Toyobo Company Limited
• Original Assignee: Toyobo Company Limited
• Inventors: Haruta, Masayuki, Ishimaru, Shintaro
• Primary Examiner(s): Chen, Vivian
• Application Number:
  US15/300,774
• Publication Number:
  US 20170021601A1
• Time in Patent Office: 1,246 Days
• Field of Search: None
• CPC Class Codes: B29C 55/005 characterised by the choice of materials
• CPC Class Codes: B29C 55/143 firstly parallel to the direction of feed and then transversely thereto
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0049 Heat shrinkable
• CPC Class Codes: B29K 2995/0053 bi-axially
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 2307/582 Tearability
• CPC Class Codes: B32B 2307/736 Shrinkable
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 2309/04 Time
• CPC Class Codes: B32B 2439/00 Containers; Receptacles
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B65D 2203/02 Labels
• CPC Class Codes: B65D 23/0878 Shrunk on the bottle
• CPC Class Codes: B65D 75/00 Packages comprising articles or materials partially or wholly enclosed in strips, sheets, blanks, tubes, or webs of flexible sheet material, e.g. in folded wrappers B65D71/00 takes precedence; wrapping B65B11/00
• CPC Class Codes: B65D 75/002 in shrink films B65D71/08 takes precedence
• CPC Class Codes: C08G 63/183 Terephthalic acids
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 2467/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08J2467/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 67/02 : Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: Y10T 428/1328 : Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
• CPC Class Codes: Y10T 428/31786 : Of polyester [e.g., alkyd, etc.]

Abstract

The invention provides a heat shrinkable polyester film which has (1) a hot-water heat shrinkage of not less than 55% and not more than 90% in a main shrinking direction of the film when dipped in hot water at 98° C.; (2) a hot-water heat shrinkage of not less than −5% and not more than 12% in a direction orthogonal to the main shrinking direction of the film when dipped in hot water at 98° C.; (3) a difference in specific heat capacity ΔC_p between at a lower and a higher temperature than Tg of not less than 0.1 J/(g·° C.) and not more than 0.7 J/(g·° C.) when a reverse heat flow is measured with a temperature modulated DSC; and (4) a tensile breaking strength of not less than 70 MPa and not more than 150 MPa in the direction orthogonal to the main shrinking direction of the film.

Claims

1. A heat shrinkable polyester film which satisfies the following requirements (1) to (4):

(1) the film has a hot-water heat shrinkage of not less than 55% and not more than 90% in a main shrinking direction of the film when dipped in hot water at 98°

C. for 10 seconds;

(2) the film has a hot-water heat shrinkage of not less than −

5% and not more than 12% in a direction orthogonal to the main shrinking direction of the film when dipped in hot water at 98°

C. for 10 seconds;

(3) the film has a difference in specific heat capacity Δ

C_p between at a lower and a higher temperature than Tg of not less than 0.1 J/(g·

°

C.) and not more than 0.7 J/(g·

°

C.) when a reverse heat flow is measured with a temperature modulated DSC; and

(4) the film has a tensile breaking strength of not less than 70 MPa and not more than 150 MPa in the direction orthogonal to the main shrinking direction of the film.

2. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 1 and then shrinking the label on the covered object by heat.

3. The heat-shrinkable polyester film according to claim 1, wherein the film has a maximum shrinkage stress of not less than 2 MPa and not more than 14 MPa in the main shrinking direction of the film measured with hot air at 90°

C., and a shrinkage stress of not less than 60% and not more than 100% of the maximum shrinkage stress 30 seconds after measurement start.

4. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 3 and then shrinking the label on the covered object by heat.

5. The heat-shrinkable polyester film according to claim 3, wherein the film has a right-angled tearing strength per unit thickness of not less than 180 N/mm and not more than 350 N/mm in the direction orthogonal to the main shrinking direction of the film after being shrunk by 10% in the main shrinking direction in hot water at 80°

C.

6. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 5 and then shrinking the label on the covered object by heat.

7. The heat-shrinkable polyester film according to claim 5, which is biaxially drawn in the main shrinking direction and in the direction orthogonal to the main shrinking direction.

8. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 7 and then shrinking the label on the covered object by heat.

9. The heat-shrinkable polyester film according to claim 3, which is biaxially drawn in the main shrinking direction and in the direction orthogonal to the main shrinking direction.

10. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 9 and then shrinking the label on the covered object by heat.

11. The heat-shrinkable polyester film according to claim 1, wherein the film has a right-angled tearing strength per unit thickness of not less than 180 N/mm and not more than 350 N/mm in the direction orthogonal to the main shrinking direction of the film after being shrunk by 10% in the main shrinking direction in hot water at 80°

C.

12. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 11 and then shrinking the label on the covered object by heat.

13. The heat-shrinkable polyester film according to claim 11, which is biaxially drawn in the main shrinking direction and in the direction orthogonal to the main shrinking direction.

14. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 13 and then shrinking the label on the covered object by heat.

15. The heat-shrinkable polyester film according to claim 1, which is biaxially drawn in the main shrinking direction and in the direction orthogonal to the main shrinking direction.

16. A package formed by covering at least a part of an outer periphery of an object to be packaged with a label obtained from the heat-shrinkable polyester film according to claim 15 and then shrinking the label on the covered object by heat.