Heat-shrinkable polyester film, and production method therefor and package thereof

Patent metadata

Field	Value
Publication number	US-10173818-B2
Application number	US-201615745990-A
Country	US
Kind code	B2
Filing date	Jul 22, 2016
Priority date	Jul 24, 2015
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

The invention provides a heat-shrinkable polyester film which has a high heat shrinkage rate in the width direction, exhibits a low heat shrinkage rate in the longitudinal direction, and has a great mechanical strength in the longitudinal direction, good openability along perforations, and excellent shrink finish. The film has a hot-water heat shrinkage rate of 40% to 85% in the main shrinking direction and −5% to 15% in the perpendicular direction when the film is immersed in hot water at 98° C. for 10 seconds, and a maximum shrinkage stress of 2-7 MPa in the main shrinking direction when measured in hot air of 90° C. and the shrinkage stress 30 seconds after measurement of the shrinkage stress has started is of 60-100% of the maximum shrinkage stress. The film contains 6 mol % or more of diethylene glycol-derived constituent units with respect to 100 mol % of all polyester resin components.

First claim

The invention claimed is:

1. A heat-shrinkable polyester film which satisfies the following requirements (1) to (4):
(1) the hot-water heat shrinkage rate when the film is immersed in hot water at 98° C. for 10 seconds is 40% or more and 85% or less in the main shrinking direction of the film;
(2) the hot-water heat shrinkage rate when the film is immersed in hot water at 98° C. for 10 seconds is -5% or more and 15% or less in a direction perpendicular to the main shrinking direction of the film;
(3) the maximum shrinkage stress is 2 MPa or more and 7 MPa or less in the main shrinking direction of the film when measured in hot air of 90° C., and the shrinkage stress 30seconds after measurement of the shrinkage stress has started is 60% or more and 100% or less of the maximum shrinkage stress; and
(4) the film contains 6 mol % or more of diethylene glycol-derived constituent units with respect to 100 mol % of all polyester resin components.

2. A method for producing the heat-shrinkable polyester film according to claim 1 , comprising a drawing process in the main shrinking direction and a drawing process in a direction perpendicular to the main shrinking direction.

3. The heat-shrinkable polyester film according to claim 1 , wherein the main shrinking direction is a width direction of the film.

4. The heat-shrinkable polyester film according to claim 1 , wherein the main shrinking direction is a longitudinal direction of the film.

5. The heat-shrinkable polyester film according to claim 1 , wherein the tensile breaking strength in a direction perpendicular to the main shrinking direction of the film is 60 MPa or more and 180 MPa or less.

6. The heat-shrinkable polyester film according to claim 1 , wherein the right-angled tearing strength per unit thickness in a direction perpendicular to the main shrinking direction after shrinking by 10% in hot water at 80° C. in the main shrinking direction is 180 N/mm or more and 350 N/mm or less.

7. The heat-shrinkable polyester film according to claim 1 , wherein the haze is 2% or more and 18% or less.

8. The heat-shrinkable polyester film according to claim 1 , wherein ethylene terephthalate is a main constituent component, and 13 mol % or more of a monomer component capable of forming an amorphous component is contained in all polyester resin components.

9. The heat-shrinkable polyester film according to claim 8 , wherein the main shrinking direction is a width direction of the film.

10. The heat-shrinkable polyester film according to claim 9 , wherein the tensile breaking strength in a direction perpendicular to the main shrinking direction of the film is 60 MPa or more and 180 MPa or less.

11. The heat-shrinkable polyester film according to claim 10 , wherein the right-angled tearing strength per unit thickness in a direction perpendicular to the main shrinking direction after shrinking by 10% in hot water at 80° C. in the main shrinking direction is 180 N/mm or more and 350 N/mm or less.

12. The heat-shrinkable polyester film according to claim 11 , wherein the haze is 2% or more and 18% or less.

13. The heat-shrinkable polyester film according to claim 8 , wherein the main shrinking direction is a longitudinal direction of the film.

14. The heat-shrinkable polyester film according to claim 13 , wherein the tensile breaking strength in a direction perpendicular to the main shrinking direction of the film is 60 MPa or more and 180 MPa or less.

15. The heat-shrinkable polyester film according to claim 14 , wherein the right-angled tearing strength per unit thickness in a direction perpendicular to the main shrinking direction after shrinking by 10% in hot water at 80° C. in the main shrinking direction is 180 N/mm or more and 350 N/mm or less.

16. The heat-shrinkable polyester film according to claim 15 , wherein the haze is 2% or more and 18% or less.

17. The heat-shrinkable polyester film according to claim 8 , wherein the tensile breaking strength in a direction perpendicular to the main shrinking direction of the film is 60 MPa or more and 180 MPa or less.

18. The heat-shrinkable polyester film according to claim 17 , wherein the right-angled tearing strength per unit thickness in a direction perpendicular to the main shrinking direction after shrinking by 10% in hot water at 80° C. in the main shrinking direction is 180 N/mm or more and 350 N/mm or less.

19. The heat-shrinkable polyester film according to claim 18 , wherein the haze is 2% or more and 18% or less.

20. 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.

Assignees

• Toyo Boseki

Inventors

• Haruta Masayuki
• Ishimaru Shintaro

Classifications

• B29K2067/003

  PET, i.e. poylethylene terephthalate · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title

• B29K2995/0049

  Heat shrinkable · CPC title

• B65D77/22

  Details · CPC title

• B65D25/20

  External fittings (of containers made by folding or erecting blanks made of paper B65D5/44) · CPC title