Method and apparatus for making a peelable film

• US 5,779,832 A
• Filed: 11/25/1996
• Issued: 07/14/1998
• Est. Priority Date: 11/25/1996
• Status: Expired due to Fees

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: W R Grace & Company - CONN (WR Grace & Company)
• Inventors: Kocher, Patrick N.
• Primary Examiner(s): CRISPINO, RICHARD D
• Application Number:
  US08/756,205
• Time in Patent Office: 596 Days
• Field of Search: 156/73.1, 156/152, 156/252, 156/272.6, 156/308.2, 156/379.6, 156/380.7, 156/497, 156/513, 156/514, 156/582
• US Class Current: 156/73.1
• CPC Class Codes: B32B 2307/724 Permeability to gases, adsorption
• CPC Class Codes: B32B 2310/028 using vibration, e.g. sonic or ultrasonic
• CPC Class Codes: B32B 2310/0843 using laser
• CPC Class Codes: B32B 38/0008 Electrical discharge treatment, e.g. corona, plasma treatment; wave energy or particle radiation heat treatment B32B38/0036
• CPC Class Codes: B32B 38/04 Punching, slitting or perforating
• CPC Class Codes: Y10T 156/1056 Perforating lamina

Abstract

A method of making a peelable film comprises providing a multilayer film; delaminating the film into a first portion and a second portion; treating the second portion to increase its gas permeability; and relaminating the treated second portion to the first portion. In another aspect of the invention, an apparatus for making a peelable film comprises a means for delaminating a film into a first portion and a second portion; a means for treating the second portion to increase its gas permeability; and a means for relaminating the treated second portion to the first portion. Perforations, partial perforations, and other film treatments can be thus advantageously utilized in connection with a second, preferably gas permeable portion of a peelable film, without affecting a first, preferably gas impermeable portion of the same film.

Claims

1. A method of making a peelable film comprising:

a) providing a multilayer thermoplastic film;

b) delaminating the film along a first interface into a first gas impermeable portion having a permeability of less than 1000 cc of gas per square meter of film per 24 hour period at 1 atmosphere and at a temperature of 73°

F., and a second gas permeable portion having a permeability of at least 1000 cc of gas per square meter of film per 24 hour period at 1 atmosphere and at a temperature of 73°

F.

c) perforating the second portion to increase its gas permeability; and

d) relaminating the perforated second portion to the first portion along the first interface.

2. The method of claim 1 wherein the peelable film, after the step of relaminating the perforated second portion to the first portion, comprises a first layer, and a second layer, the first and second layers adjacent each other and forming a peelable interlaminar interface between the adjacent layers.

3. The method of claim 2 wherein the first adjacent layer comprises a polyethylene homopolymer or copolymer, and the second adjacent layer comprises a material selected from the group consisting of polyamide, copolyamide, polyester, copolyester, propylene homopolymer, and propylene copolymer.

4. The method of claim 1 wherein the first portion and second portion are relaminated together by corona treating a surface of the first portion, and bringing the corona treated surface of the first portion into contact with the second portion.

5. The method of claim 1 wherein the first portion and second portion are relaminated together by corona treating a surface of the second portion, and bringing the corona treated surface of the second portion into contact with the first portion.

6. The method of claim 1 wherein the first portion and second portion are relaminated by heat sealing the first and second portions together.

7. The method of claim 6 wherein the first and second portions are heat sealed together under pressure.

8. The method of claim 1 wherein the first portion and second portion are relaminated by ultrasonically sealing the first and second portions together.