Heat shrinkable polyester film

• US 6,720,085 B2
• Filed: 10/17/2001
• Issued: 04/13/2004
• Est. Priority Date: 07/28/2000
• Status: Expired due to Term

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Hayakawa, Satoshi, Nakayamada, Katsuhiro, Ito, Katsuya, Tabota, Norimi
• Primary Examiner(s): Acquah, Samuel A.
• Assistant Examiner(s): BISSETT, MELANIE D
• Application Number:
  US09/978,091
• Publication Number:
  US 20020090502A1
• Time in Patent Office: 909 Days
• Field of Search: 428/480, 428/316.6, 428/212, 428/218, 428/317.9, 428/36.5, 428/36.91, 428/34.9, 428/35.1, 428/57, 428/318.4, 428/318.6, 427/336, 521/82, 521/182
• US Class Current: 428/480
• CPC Class Codes: B32B 1/08 Tubular products
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: Y10T 428/1376 Foam or porous material containing
• CPC Class Codes: Y10T 428/1393 Multilayer [continuous layer]
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24992 Density or compression of components
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/249981 Plural void-containing components
• CPC Class Codes: Y10T 428/249986 Void-containing component contains also a solid fiber or solid particle
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

The present invention relates to a heat shrinkable polyester film. The present invention also relates to a heat shrinkable polyester tube obtained from the heat shrinkable polyester film, a production method thereof, a label using this tube and a container wearing this label. The heat shrinkable polyester film of the present invention has suitable heat shrinkable properties, superior printing property and adhesion property with a solvent. When it is used for packaging (e.g., covering, bundling and the like), the film shows superior appearance and good mountability. Moreover, the heat shrinkable polyester film of the present invention has a small apparent specific gravity and is easily collected separately from a bottle when it is used as a label of a bottle (such as PET bottle).

Claims

1. A heat shrinkable polyester film comprising a first polyester layer having voids (layer A) and a polyester layer (layer B) having a smaller porosity than layer A, which is formed at least on one surface of layer A, wherein the film has a brightness of not less than 70, which permits adhesion with a solvent, and wherein the film has a percentage of heat shrinkage in hot air at 95°

C. of 30-90% in either direction of the heat shrinkable polyester film.

2. The heat shrinkable polyester file of claim 1, wherein the voids are formed by forming a polyester comprising an incompatible thermoplastic resin into a film and stretching the film at least uniaxially.

3. The heat shrinkable polyester film of claim 1, wherein the layer A is a porous polyester layer having a porosity of 5-50 vol %, and the layer B is a porous polyester layer having a porosity of 0-20 vol %.

4. The heat shrinkable polyester film of claim 3, which further comprises a polyester layer (layer C) having a porosity of 0-50 vol % formed on the other side of the layer A where the layer B is not formed.

5. The heat shrinkable polyester film of claim 1, which has a center line mean surface roughness of at least one surface of not more than 0.5 μ

m.

6. The heat shrinkable polyester film of claim 1, which has a total light transmittance of not more than 30%.

7. The heat shrinkable polyester film of claim 1, wherein the film has a heat shrinkage percentage of 0-10% in a direction perpendicular to said direction.

8. The heat shrinkable polyester film of claim 4, wherein the center line mean surface roughness (Ra1) of one surface is not more than 0.5 μ

m and the center line mean surface roughness (Ra2) of the opposite surface is greater than Ra1 by not less than 0.05 μ

m.

9. The heat shrinkable polyester film of claim 1, which further comprises organic or inorganic fine particles having a mean particle size of 0.001-5.0 μ

m as a lubricant in a proportion of 0.01-30 wt %.

10. The heat shrinkable polyester film of claim 1, wherein the layer A comprises organic or inorganic fine particle having a mean particle size of 0.001-5.0 μ

m as a lubricant in a proportion of 0.01-30 wt %.

11. The heat shrinkable polyester film of claim 1, which has an apparent specific gravity of less than 1.1.

12. The heat shrinkable polyester film of claim 1, which has an apparent specific gravity of less than 1.1 after heat shrinkage in at least one direction by 5-50%.

13. The heat shrinkable polyester film of claim 1, which further comprises at least one residue selected from a neopentylglycol residue and a cyclohexanedimenthanol residue as a component of the polyester.

14. The heat shrinkable polyester film of claim 1, which has a film thickness of 10-100 μ

m.

15. The heat shrinkable polyester film of claim 1, wherein the layer A has a thickness ratio to the layer B of 1.5-30.

16. The heat shrinkable polyester film of claim 1, which comprises a print on at least one surface.

17. A heat shrinkable polyester tube obtained by adhering the heat shrinkable polyester film of claim 1 with a solvent.

18. A container equipped with the heat shrinkable polyester film of claim 1.

19. A method for producing a heat shrinkable polyester tube, which method comprises the steps of

(a) applying at least one solvent selected from solvents having a solubility parameter within the range of 8.0-13.8 to at least one splicing area of the heat shrinkable polyester film of claim 1;

(b) splicing the heat shrinkable polyester film at splicing areas at a temperature of not more than 70°

C.; and

(c) drying the spliced film to give the tube.