Pass through stretch wrapping process

• US 4,499,706 A
• Filed: 05/19/1983
• Issued: 02/19/1985
• Est. Priority Date: 05/19/1983
• Status: Expired due to Fees

• Current Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Scheller, Andor
• Primary Examiner(s): Spruill, Robert L.
• Assistant Examiner(s): Folkerts, Michael D.
• Application Number:
  US06/496,168
• Time in Patent Office: 642 Days
• Field of Search: 53/170, 53/176, 53/229, 53/397, 53/399, 53/441, 53/442, 53/449, 53/463, 53/466, 53/556, 53/557, 53/586, 383/112, 383/119, 383/908
• US Class Current: 53/399
• CPC Class Codes: B65B 11/585 to stacked articles, e.g. pallettised loads
• CPC Class Codes: B65B 9/026 the webs forming a curtain
• CPC Class Codes: B65D 2571/0003 Mechanical characteristics of the stretch film
• CPC Class Codes: B65D 71/0096 the dimensions of the supports corresponding to the periphery of the load, e.g. pallets

Abstract

A double layer thermoplastic film is used in Pass-Through stretch wrapping of goods. The double layer improves the tear resistance and puncture resistance of the film.

Claims

1. A method of bundling a body of goods which comprise stretching under tension a dual layer film of a thermoplastic circumferentially around the body, and joining the film together at a line where the film meets to encircle the body;

said film having sufficient elongation to permit at least 10% stretching under tension and sufficient slip between the layers of the film to permit relative slippage, and wherein the molecules of one layer of the film are aligned generally crosswise of the molecules of the second layer of film thereby increasing tear resistance of the dual layer film.

2. The method as defined in claim 1 wherein the film is a copolymer of ethylene and an alpha-olefin and wherein each layer is no more than 2 mils thick.

3. The method as defined in claim 1 wherein the film has a coefficient of friction of between about 0.2 and 0.5.

6. The process of claim 1 wherein the thermoplastic is a homopolymer or copolymer of ethylene.

4. In a pass through, stretch packaging process wherein two film webs joined together on one side of a body of goods to be packaged are stretched in opposite directions circumferentially around the body and with the tension retained, the web portions are joined together on the side opposite said one side by heat sealing, the improvement wherein the film webs are flattened tubes of a thermoplastic having (a) sufficient elasticity to permit said stretching and (b) sufficient slippage to permit the film layers to slide relative to one another during the stretching operation;

the molecules of one layer of the tube are oriented generally crosswise of the molecules of the second layer of the tube.

5. The method of claim 4 wherein each film layer has a thickness of between 0.5 and 2.0 mils and a coefficient of friction of between 0.2 and 0.5.

7. The process of claim 4 wherein the thermoplastic is a copolymer of ethylene and an alpha-olefin.

8. The process of claim 7 wherein the copolymer is produced by a low pressure process.

9. The process of claim 4 wherein the film further includes upper and lower gussets aligned to wrap around the upper portion and lower portion respectively of the goods to be packaged.

10. The process of claim 4 wherein the film comprises a flattened tube produced by the blown film method.