Multi-layer film for forming a vacuum packaging bag and method of manufacture
A vacuum packaging film with an improved embossed pattern suitable for evacuation of gas from a vacuum packaging bag made of the film. The embossed pattern includes a plurality of roughly parallel sequences of substantially collinear ridges. The ridges of a first sequence are offset with respect to the ridges of an adjacent second sequence.
This application claims priority to U.S. Provisional Patent Application No. 60/611,114, entitled “MULTI-LAYER FILM FOR FORMING A VACUUM PACKAGING BAG AND METHOD OF MANUFACTURE”, by Hongyu Wu, filed on Sep. 17, 2004, and which is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTIONThe present invention relates generally to vacuum packaging film, and more particularly to patterned vacuum packaging film.
BACKGROUND OF THE INVENTIONVacuum packaging film is used for vacuum sealing of perishable items. Due to the film's versatility in producing vacuum sealed packages of various sizes, its popularity has increased in recent years. As a result, continuous product improvement is required on the part of manufacturers in order to stay competitive. One such improvement has been applying patterns to vacuum packaging bags.
For vacuum packaging bags with smooth inner surfaces (i.e., inner surfaces that do not have a pattern), the bag surfaces sometimes stick together when air is evacuated from the bag during vacuum packaging. This may result in air pockets within the seal and degraded seal integrity. In response to this problem, manufacturers may imprint or emboss a pattern onto vacuum packaging film used to form the vacuum packaging bags. The pattern helps prevent vacuum packaging bag surfaces from sticking together during vacuum packaging by forming channels along the grooves of an imprinted pattern—or forming channels between raised portions of an embossed pattern—when the surfaces of the bag are face to face. The pattern may be applied to one or both of the inner surfaces of the vacuum packaging bag.
While imprinting or embossing a pattern onto vacuum packaging film is generally desirable, imprinting or embossing a pattern introduces new problems. For example, embossed patterns may be less durable than smooth surfaces. In general, the farther an embossed pattern sticks out from the surface of vacuum packaging film, the less durable the film becomes. Moreover, thicker embossing—or deeper grooves—typically consumes more material and may be harder to apply to or form into the film. Thicker embossing—or deeper grooves—also typically results in thicker vacuum packaging film, which makes the film heavier and less compact so it takes up more space in storage. Furthermore, if the surface of a vacuum packaging film has a high concentration of raised areas, there will be fewer channels formed when evacuating a vacuum packaging bag made of the film. Since there are fewer channels, even if relatively few channels become blocked gas may be trapped and air pockets formed, resulting in degraded seal integrity.
Accordingly, what is needed is a vacuum packaging film with an improved embossing pattern to reduce embossing thickness, to reduce the concentration of raised areas on vacuum packaging film, or to increase the number of channels formed when the vacuum packaging film is used in a vacuum packaging application.
SUMMARY OF THE INVENTIONThe present invention fills these needs by providing a vacuum packaging film with an improved embossed pattern suitable for evacuation of gas from a vacuum packaging bag made of the film. In an aspect of the present invention, the embossed pattern includes a plurality of roughly parallel sequences of substantially collinear ridges. The ridges of a first sequence are offset with respect to the ridges of an adjacent second sequence.
A method for making vacuum packaging film, in accordance with an aspect of the present invention, includes heat extruding a first material onto a spinning cooling roll and heat extruding a second material onto the spinning cooling roll. The first and second extruded materials bond and form a film of the first material with a plurality of roughly parallel sequences of substantially collinear ridges of the second material forming a pattern on the film. The pattern is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made from the film.
A vacuum packaging bag made of the vacuum packaging film according to an aspect of the present invention includes a first sheet and a second sheet. The first and second sheets are formed of the vacuum packaging film. The second sheet has a footprint substantially similar to the first sheet. The first and second sheets are arranged with respective second layers facing one another. The first and second sheets are sealed on opposing lateral sides and an end side, whereby the first and second sheets form a vacuum packaging bag with an opening for insertion of food or other product. The vacuum packaging bag is sealable at the opening.
A vacuum packaging bag roll, suitable for forming vacuum packaging bags, made of the vacuum packaging film according to an aspect of the present invention includes a first sheet and a second sheet. The first and second sheets are formed of the vacuum packaging film. The second sheet has a footprint substantially similar to the first sheet. The first and second sheets are arranged with respective second layers facing one another. The first and second sheets are sealed on opposing lateral sides, wherein portions of the bag roll may be cut from the bag roll thereby creating a partially formed bag having opposing ends that are unsealed. Sealing one end of a partially formed bag forms a vacuum packaging bag with an opening at the other end.
An advantage of the present invention is that the configuration of ridges of an embossed pattern allows gas to flow around blockages through alternative paths. Moreover, a patterned vacuum packaging film can be produced economically.
These and other advantages of the present invention will become apparent to those skilled in the art after reading the following descriptions and studying the various figures of the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention provides a new embossed pattern for a surface of a vacuum packaging film. The term embossed, as used herein, is intended to mean that a pattern is raised or in relief and is not intended to imply a particular technique—such as cold-pressing, extrusion, or imprinting—used to apply the pattern. The embossed pattern is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of the film. The pattern, due to its advantageous configuration, should reduce the relative concentration and height of embossed ridges on the surface of the film. In an embodiment, the embossed pattern includes a plurality of roughly parallel sequences of substantially collinear ridges, where ridges of a first sequence are offset with respect to ridges of an adjacent second sequence. The offset ridges are operable to form multiple channel paths through which gas flows during evacuation of the vacuum packaging bag. Due to the offset, if a channel becomes clogged or collapsed, gas will seek one of many other alternative paths. The vacuum packaging film and an exemplary method for manufacturing the film will now be described. It should be noted that certain extraneous details were left out of the subsequent description in an effort to not unnecessarily obscure the true spirit and scope of the present invention.
The alternative zigzag pattern 200B and wavy pattern 200C are analogous to the zigzag pattern 200A so they are not described in detail herein. Moreover, it should be noted that the patterns of
It should be noted that the vacuum packaging film 100 could be made with as few as two layers, a gas-impermeable layer and a heat-sealable resin layer, bonded together without a bonding layer between them. The bonding layers and structural layer are optional in this embodiment. Moreover, in an alternative, the heat-sealable resin layer could be replaced with any sealable material, such as glue.
It should be noted that the method of manufacture using a multi-layer extruder 402 is for illustrative purposes only. While the manufacturing technique can produce a vacuum packaging film with the advantageous qualities described herein, some other technique for imprinting a pattern onto a vacuum packaging film will also suffice, as is well-known in the art of vacuum packaging film manufacturing. It should further be noted that, depending on the technique for imprinting the pattern, a multi-layer vacuum packaging film may have the pattern imprinted on one or more of the multiple layers, or the pattern may simply be embossed only on the heat-sealable resin layer.
While this invention has been described in terms of certain embodiments, it will be appreciated by those skilled in the art that modifications, permutations and equivalents thereof are within the inventive scope of the present invention. It is therefore intended that the following appended claims include such modifications, permutations and equivalents as fall within the true spirit and scope of the present invention. Moreover, the embodiments described herein are for exemplary purposes only and should not be construed to capture every embodiment of the invention. The invention is limited only by the claims.
Claims
1. A multi-layer film suitable for use in forming a vacuum packaging bag, said multi-layer film comprising:
- a first layer made of a first material; and
- a second layer made of a second material that is formed onto said first layer, said second layer having a pattern that is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of said film, said pattern including a plurality of roughly parallel sequences of substantially collinear ridges, wherein ridges of a first sequence of said parallel sequences of substantially collinear ridges are offset with respect to an adjacent second sequence of said parallel sequences of substantially collinear ridges.
2. The film of claim 1, wherein said first material is a gas-impermeable material, and wherein said first layer is a gas-impermeable layer.
3. The film of claim 1, wherein said pattern is embossed onto said first layer as well as said second layer.
4. The film of claim 1, wherein said second material is a heat-sealable resin, and wherein said second layer is a heat-sealable resin layer.
5. The film of claim 4, wherein said heat-sealable resin is a polyethylene resin.
6. The film of claim 1, further comprising a third material in between said first material and said second material, said third material forming a bonding layer between said first and second layers.
7. The film of claim 1, further comprising a fourth material and a fifth material, said fourth material forming a bonding layer between said first layer and a fifth layer made of said fifth material, wherein said fifth layer is a structural layer for providing structural strength to said film.
8. The film of claim 1, wherein said substantially collinear ridges have a striped pattern.
9. The film of claim 1, wherein said substantially collinear ridges have a zigzag pattern.
10. The film of claim 1, wherein said substantially collinear ridges have a wave pattern.
11. The film of claim 1, wherein said substantially collinear ridges have an uneven pattern.
12. A method of manufacturing a multi-layer film for use in vacuum packaging applications, said multi-layer film having a pattern that operates to form channels suitable for evacuation of gas when said multi-layer film is used in the creation of a vacuum packaging bag, said method comprising the acts of:
- heat-extruding a first material onto a roller; and
- heat-extruding a second material onto said roller such that said first and second extruded materials bond and form a film of said first material with a plurality of roughly parallel sequences of substantially collinear ridges of said second material forming a pattern on said film, said pattern operable to form channels suitable for evacuation of gas from a vacuum packaging bag made from said film.
13. The method of claim 12, wherein said first material is a gas-impermeable material, said method further comprising forming a gas-impermeable layer as a first layer of said film.
14. The method of claim 14, further comprising the act of heat-extruding a third material in between said first and second material, wherein said third material forms a bonding layer between a first layer made of said first material and a second layer made of said second material.
15. The method of claim 12, further comprising the act of heat-extruding a fourth material and a fifth material to respectively form a bonding layer and a structural layer, wherein said bonding layer bonds said structural layer to a first layer made of said first material, and wherein said structural layer provides structural strength to said film.
16. The method of claim 12, further comprising the act of controlling a temperature of said roller in order to properly effectuate cooling and formation of said first and second layers.
17. The method of claim 12, wherein the act of applying a pattern to said first and second layers is accomplished by providing said pattern on the circumferential surface of said roller.
18. The method of claim 12, wherein the act of applying a pattern to said first and second layers is accomplished by using an air knife to shape said first and second materials subsequent to extrusion.
19. The method of claim 19, wherein said air-knife includes an inverse vacuum, further comprising imparting said pattern on said first and second materials using said inverse vacuum.
20. A vacuum packaging bag for holding food or other product, said vacuum packaging bag comprising:
- a first sheet formed of a multi-layer plastic film, said multi-layer plastic film including: a first layer made of a first material; and a second layer made of a second material that is laminated onto said first layer, said second layer having an embossed pattern that is operable to form channels suitable for evacuation of gas from a vacuum packaging bag made of said film, said embossed pattern including a plurality of roughly parallel sequences of substantially collinear ridges, wherein ridges of a first sequence of said parallel sequences of substantially collinear ridges are offset with respect to an adjacent second sequence of said parallel sequences of substantially collinear ridges;
- a second sheet formed of said multi-layer plastic film, said second sheet having a footprint substantially similar to said first sheet, wherein said first and second sheets are arranged with respective second layers facing one another, said first and second sheets sealed on opposing lateral sides and at an end side, whereby said first and second sheets form a vacuum packaging bag having an opening for insertion of food or other product, said vacuum packaging bag sealable at said opening.
Type: Application
Filed: Jul 19, 2005
Publication Date: Apr 6, 2006
Inventor: Hongyu Wu (San Jose, CA)
Application Number: 11/185,536
International Classification: B65D 33/01 (20060101); B65D 33/00 (20060101); B65D 30/08 (20060101);