Method of film crease elimination and patch bag without crease within lay-flat bag side

• US 6,296,886 B1
• Filed: 03/17/1997
• Issued: 10/02/2001
• Est. Priority Date: 03/17/1997
• Status: Expired due to Fees

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: Cryovac Incorporated (Sealed Air)
• Inventors: Ramirez, Joseph M., Odabashian, Robert A., Moore, Donald B. Jr., Worley, Richard M., Tucker, Carl L., DePoorter, Larry W.
• Primary Examiner(s): SHERRER, CURTIS EDWARD
• Application Number:
  US08/819,841
• Time in Patent Office: 1,660 Days
• Field of Search: 426/127, 426/129, 156/277, 156/272.6, 156/302, 156/297, 156/229, 206/204, 383/119, 383/109, 493/210
• US Class Current: 426/127
• CPC Class Codes: B31B 70/003 Opening or distending bags
• CPC Class Codes: B31B 70/10 Feeding or positioning webs
• CPC Class Codes: B31B 70/876 involving application of reinforcement strips or patches; involving reinforcements obtained by folding
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B65D 33/02 Local reinforcements or stiffening inserts, e.g. wires, strings, strips or frames B65D33/007 takes precedence

Abstract

A process for removing creases from a film eliminates a problem in the quality of the heat seal for a patch bag having at least a segment of one or more bag side edges (or the bag bottom edge) covered by one or more patches. The film creases are removed by inflating the film tubing which is later converted to a bag, heating regions containing the creases with a heating means to a temperature which, in combination with the pressure within the inflated tubing, causes the creases to relax. The heated crease-containing regions are then cooled and the inflated tubing is deflated and wound up in a new configuration in which at least one patch covers at least one side edge or the bottom edge.

Claims

1. A process for making a patch bag, comprising:

(A) adhering a patch to a first lay-flat side of a film tubing while the tubing is in a first lay-flat configuration, whereby a lay-flat tubing-patch laminate is formed, the lay-flat tubing having a first crease along a first side edge and a second crease along a second side edge;

(B) passing the lay-flat tubing-patch laminate through a first pair of nip rolls with the tubing being inflated by a trapped bubble of gas between the first pair of nip rolls and a second pair of nip rolls, whereby an inflated tubing-patch laminate is formed;

(C) heating a first region of the inflated tubing-patch laminate which contains the first crease, and a second region of the inflated tubing-patch laminate which contains the second crease, the heating being carried out so that each of the creases is removed;

(D) cooling the first and second regions of the inflated tubing-patch laminate;

(E) deflating and flattening the inflated tubing-patch laminate into a second lay-flat configuration by passing the inflated tubing-patch laminate through the second pair of nip rolls which have a nip which is oriented from about 10 to 90 degrees off-parallel relative to a nip of the first pair of nip rolls, so that a reconfigured lay-flat tubing-patch laminate is formed in which the patch covers a segment of a first new side edge of the tubing; and

(F) sealing and cutting the reconfigured lay-flat tubing-patch laminate in the second lay-flat configuration so that the patch bag is formed from a segment of the tubing having the patch adhered thereto.

2. The process according to claim 1, wherein:

the first and second regions of the tubing-patch laminate are each heated to a temperature of from about 140 to 170°

F.; and

the cooling of the first and second regions of the tubing-patch laminate cools the first and second regions to a temperature of from about 85 to 110°

F.

3. The process according to claim 2, wherein the heating is carried out by at least one member selected from the group consisting of infrared radiation and hot air, and wherein the cooling is carried out by air at from 55 to 85°

F.

4. The process according to claim 2, wherein the trapped bubble in the tubing exerts a pressure of from about 1 to 18 inches of water on an inside surface of the tubing-patch composite.

5. The process according to claim 4, wherein the sealing and cutting is carried out so that a side-seal patch bag is produced, with the patch covering at least a segment of the bottom of the bag.

6. The process according to claim 5, wherein the second pair of nip rolls is oriented from about 60 to 90 degrees off-parallel relative to the first pair of nip rolls.

7. The process according to claim 6, wherein the patch is adhered to the outside surface of the tubing.

8. The process according to claim 4, wherein a first patch is adhered to a first lay-flat side of the tubing, a second patch is adhered to a second lay-flat side of the tubing, and upon deflation and flattening into the second lay-flat configuration, the first patch covers a segment of the new first side edge and the second patch covers a segment of the new second side edge;

and wherein the cutting and sealing are carried out so that an end-seal patch bag is produced.

9. The process according to claim 8, wherein the tubing has a first uncovered region which is between the first patch and the second patch and which has a width of from about 0.2 inch to 2 inches, and a second uncovered region which is also between the first patch and the second patch and which also has a width of from about 0.2 to 2 inches.

10. The process according to claim 9, wherein the second pair of nip rolls is oriented about 90 degrees off-parallel relative to the first pair of nip rolls.

11. The process according to claim 10, wherein the tubing comprises a first multilayer, biaxially-oriented, heat-shrinkable film, the first patch comprises a second multilayer, biaxially-oriented, heat-shrinkable film, and the second patch comprises a third multilayer, biaxially-oriented, heat-shrinkable film.

12. The process according to claim 11, wherein:

(A) the first film comprises;

(i) an outside abuse layer comprising at least one member selected from the group consisting of ethylene/alpha-olefin copolymer having a density of from about 0.85 to 0.95, propylene/ethylene copolymer, polyamide, ethylene/vinyl acetate copolymer, ethylene/methyl acrylate copolymer, and ethylene/butyl acrylate copolymer;

(ii) an inner O₂-barrier layer comprising at least one member selected from the group consisting of ethylene/vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, polyamide, polyester, polyacrylonitrile; and

(iii) an inside sealant layer comprising at least one member selected from the group consisting of thermoplastic polyolefin, thermoplastic polyamide, thermoplastic polyester, and thermoplastic polyvinyl chloride; and

(B) the second film and the third film each comprise at least one member selected from the group consisting of ethylene/alpha-olefin copolymer having a density of from about 0.85 to 0.95, propylene/ethylene copolymer, polyamide, ethylene/vinyl acetate copolymer, ethylene/methyl acrylate copolymer, and ethylene/butyl acrylate copolymer.

13. The process according to claim 12, wherein:

the first film has a total thickness of from about 1.5 to 5 mils and a total free shrink, at 185°

F., of from about 20 to 120 percent;

the second film has a total thickness of from about 2 to 8 mils and a total free shrink, at 180°

F., of from about 10 to 100 percent; and

the third film has a total thickness of from about 2 to 8 mils and a total free shrink, at 180°

F., of from about 10 to 100 percent.

14. The process according to claim 4, wherein the film tubing comprises a first biaxially-oriented film, and the patch comprises a second biaxially oriented film.

15. The process according to claim 4, wherein the patch is adhered to the tubing with an adhesive.

16. The process according to claim 15, wherein patch is adhered to an outside surface of the tubing.