Packaging method using thermoplastic materials and package obtained thereby

• US 5,744,181 A
• Filed: 02/20/1996
• Issued: 04/28/1998
• Est. Priority Date: 03/01/1995
• Status: Expired due to Term

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: W R Grace & Company - CONN (WR Grace & Company)
• Inventors: Sornay, Jean Denis, Da Silva, Philippe Gomes
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US08/603,794
• Time in Patent Office: 798 Days
• Field of Search: 426/106, 426/129, 426/392, 264/328.1, 264/544, 53/452, 53/467, 53/478, 53/485
• US Class Current: 426/106
• CPC Class Codes: B65D 77/2024 the cover being welded or adhered to the container

Abstract

The invention is a packaging method including providing a tray with heat-sealable rims; loading the tray with a product to be packaged; applying a lid on top of the tray, the tray rims and lid having contacting surfaces being made of materials which can be heat bonded to each other at a lid sealing station to effect sealing of the lid to the tray rims, the lid comprising a biaxially oriented heat-shrinkable film having a maximum shrink force, measured at the temperature in the lid sealing station during sealing, of 0.05 kg/cm in at least the transverse direction; and heat-sealing the lid to the tray rims. A modified atmosphere can be introduced between the lid and the tray. The invention is also a package including a product; a tray in which the product is placed, the tray having heat-sealable rims; and a lid heat-sealed to the tray rims, wherein the lid comprises a biaxially oriented heat-shrinkable film having a maximum shrink force of 0.05 kg/cm in at least the transverse direction.

Claims

1. A packaging method comprising:

a) providing a tray with heat-sealable rims;

b) loading said tray with a product to be packaged;

c) applying a heat-sealable lid on top of the tray, the lid comprising a biaxially oriented heat-shrinkable film having a maximum shrink force, measured at the temperature in the lid sealing station during sealing, of 0.05 kg/cm in at least the transverse direction; and

(d) heat-sealing said lid to the tray rims.

2. The method of claim 1 wherein the biaxially oriented heat-shrinkable film has a maximum shrink force, measured at the temperature in the lid sealing station during sealing, of 0.04 kg/cm.

3. The method of claim 2 wherein the biaxially oriented heat-shrinkable film has a maximum shrink force, measured at the temperature in the lid sealing station during sealing, of 0.03 kg/cm.

4. The method of claim 1 wherein the tray is thermoformed or injection moulded.

5. The method of claim 1 wherein the biaxially oriented heat-shrinkable film has a thickness of between 14 and 40 micrometers.

6. The method of claim 1 wherein the biaxially oriented heat-shrinkable film has a free shrink, measured at the temperature in the lid sealing station during sealing, of at least 10% in at least the transverse direction.

7. The method of claim 1 wherein a modified atmosphere is introduced between said lid and said tray.

8. The method of claim 1, wherein the film has a maximum shrink force, measured at 120°

C., of 0.05 kg/cm in at least the transverse direction.

9. The method of claim 1, wherein the film has a maximum shrink force, measured at 120°

C., of 0.04 kg/cm in at least the transverse direction.

10. The method of claim 1, wherein the film has a maximum shrink force, measured at 120°

C., of 0.03 kg/cm in at least the transverse direction.

11. A package comprising:

a) a product;

b) a tray in which the product is placed, the tray having heat-sealable rims; and

c) a lid heat-sealed to the tray rims, wherein the lid comprises a biaxially oriented heat-shrinkable film having a maximum shrink force of 0.05 kg/cm in at least the transverse direction.

12. The package as in claim 11 wherein the biaxially oriented heat-shrinkable film has a maximum shrink force of 0.04 kg/cm in at least the transverse direction.

13. The package as in claim 11 wherein the biaxially oriented heat-shrinkable film has a maximum shrink force of 0.03 kg/cm in at least the transverse direction.

14. The package of claim 11 wherein the tray is a thermoformed or injection moulded tray.

15. The package of claim 11 wherein the biaxially oriented heat-shrinkable film has a thickness of between 14 and 40 micrometers.

16. The package of claim 11 wherein the biaxially oriented heat-shrinkable film has a free shrink of at least 10% in at least the transverse direction.

17. The package of claim 11 wherein a modified atmosphere is disposed between said lid and said tray.

18. The package of claim 11 wherein the film has a maximum shrink force, measured at 120°

C., of 0.05 kg/cm in at least the transverse direction.

19. The package of claim 11 wherein the film has a maximum shrink force, measured at 120°

C., of 0.04 kg/cm in at least the transverse direction.

20. The package of claim 11 wherein the film has a maximum shrink force, measured at 120°

C., of 0.03 kg/cm in at least the transverse direction.