WO2004108557A2

WO2004108557A2 - Food bag release valve

Info

Publication number: WO2004108557A2
Application number: PCT/US2004/017385
Authority: WO
Inventors: Richard L. Sandt; William G. Hartman
Original assignee: Avery Dennison Corporation
Priority date: 2003-05-30
Filing date: 2004-06-01
Publication date: 2004-12-16
Also published as: WO2005000706A1; WO2004108556A1; WO2004108557B1; WO2004108557A3; WO2004108556B1; WO2005000706B1

Abstract

A release valve (10) for a food bag (12) comprises a vent layer (30), a cover layer (32) positioned thereover, and an adhesive area (50) for attachment of the vent layer (30) to the bag's front panel (14). An area (56) is defined between the vent layer (30) and the cover layer (32), this area (56) includes passageways (44) through which the expected fluid passes to exit the valve (10). Anti-stick means are provided for preventing the adhesive (50) from causing the cover layer (32) to stick to the vent layer (30) in the area (56) and thereby block the passageways (44).

Description

Title: FOOD BAG RELEASE VALVE

RELATED APPLICATIONS For the purposes of the United States, this application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 60/474,735 filed on May 30, 2003 and U.S. Provisional Application No. 60/516,791 filed on November 3, 2003. The entire disclosures of these earlier provisional applications are hereby incorporated by reference. Also, a PCT Application (Attorney Docket AVER3456WOB, Express Mail Label EV 434053255US), and a PCT Application (Attorney Docket AVERP3456WOC, Express Mail Label EV 434053241 US), each entitled "FOOD BAG RELEASE VALVE", are being filed con-currently herewith. The entire disclosures of these con-currently filed applications are also hereby incorporated by reference.

FIELD OF THE INVENTION This invention relates generally, as indicated, to a food bag release valve and, more particularly, to a valve for selectively releasing unwanted gas from a food bag.

BACKGROUND OF THE INVENTION Food bags are commonly used by consumers and industries to store food for later use or consumption. The elimination of air from the interior cavity of the freezer bag is known to dramatically decrease freezer burn. To this end, a food bag can include an air release valve to selectively release gas from the bag structure. As with most products, it is a commercial priority to mass-manufacture such release valves in an economic and efficient manner. Also, there are many advantages to manufacturing valves at one location and separately manufacturing bag structures at a different (and possibly distant) location. With such separate manufacturing, the valves could be shipped from the valve-manufacturing location to the bag-making location, whereat they are integrated into bag structures, either by hand or machine, in a late production stage. SUMMARY OF THE INVENTION The present invention provides a valve design which allows economic and efficient mass-manufacturing, which can maintain integrity during shipping to distant locations, and/or which can be easily integrated with bag structures during latter phases of production.

More particularly, the present invention provides a release valve comprising a vent layer and a cover layer. The vent layer is positioned over an opening in the bag structure and is made of a material (e.g., a non-woven fabric) that is pervious with respect to an expected fluid (e.g., air). The cover layer is made of a material (e.g., a polymer film) that is impervious with respect to both expected gasses and expected liquids. The vent layer is attached to the bag structure by an adhesive (i.e., a bag-to-vent adhesive). The non-adhesive area between the vent layer and the cover layer define a passageway through which released air flows to exit the valve. For example, this area can be a baffle area which defines perpendicular passageways between the vent layer and the cover layer.

The bag-to-vent adhesive often occupies a region aligned with the non- adhesive area (e.g., the baffle area) between the vent layer and the cover layer. Thus, if the adhesive were to migrate through the vent layer in this region, adhesive could find its way into non-adhesive area, causing the cover layer to "stick to" the vent layer in this area. This sticking could constrict, or close, the passageway through which the released gas flows to exit the valve, thereby inhibiting the valve's proper operation. The migration of the bag-to-vent adhesive to the non-adhesive area could occur at many times during the life of the valves. For example, this migration could start during production of the valves, as early as when the bag-to- vent adhesive is applied to the vent material. Alternatively, migration could first begin during storage or shipment of the valves, even if with valves coming off the production line migration-free.

The present invention provides anti-stick means for preventing the bag-to- vent adhesive from causing the cover layer to stick to the vent layer in the area and thereby block the passageway. This means can comprise selecting the adhesive so that it has a high glass transition temperature (Tg), a high softening point, and a high viscosity. Alternatively, the adhesive area can be formed from a transfer tape and/or transferred from the release liner to reduce migration. Rollers encountering the just-applied adhesive can also be cooled to promote solidification.

The anti-stick means can comprise barrier means (e.g., a barrier layer) for preventing migration of the adhesive through the vent layer. The barrier layer can be positioned on the inner surface of the vent layer or on the outer surface of the vent layer, and/or can be coextensive (or not) with the bag-to-vent adhesive area. Additionally or alternatively, the anti-stick means can comprise a release means (e.g., a release layer) for releasing the cover layer from the vent layer should bag-to- vent adhesive migrate through vent layer. These and other features of the invention are fully described and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative embodiments of the invention, which are indicative of but a few of the various ways in which the principles of the invention may be employed.

DRAWINGS Figure 1 is a front view of a food bag, which incorporates a release valve according to the present invention.

Figures 2A - 2D are front and sectional views of the release valve. Figures 3A - 3L are schematic views of method steps for making the release valve. Figure 4 is a schematic view of equipment when making the release valve.

Figures 5A and 5B are schematic views of some modified steps. Figures 6A and 6B are schematic views of some other modified steps. Figure 7A is a sectional view similar to Figure 2B, except that the release valve includes a barrier layer on the inner surface of its vent layer. Figure 7B is a view as seen along line 7B-7B in Figure 7A.

Figure 7C is a view similar to Figure 7B, showing a modified barrier layer. Figures 7D - 7F are schematic views of steps for achieving the barrier layer shown in Figure 7C.

Figure 8A is a sectional view similar to Figure 2B, except that the release valve includes a barrier layer on the outer surface of its vent layer. Figure 8B is a view as seen along line 8B-8B in Figure 8A. Figure 8C is a view similar to Figure 8B, showing a modified barrier layer. Figures 8D - 8F are schematic views of steps for achieving the barrier layer shown in Figure 8C.

Figure 9A is a sectional view similar to Figure 2B, except that the release valve includes a release layer on the inner surface of its cover layer. Figure 9B is a view as seen along line 9B-9B in Figure 9A.

Figure 9C is a view similar to Figure 9B, with a modified release layer.

Figure 9D is a view as seen along line 9C-9C in Figure 9B.

Figures 10A - 10D are views similar to Figure 2B, except that the release valve includes a barrier layer and a release layer.

DETAILED DESCRIPTION

Referring now to the drawings and initially to Figure 1 , a release valve 10 according to the present invention is shown incorporated into a food bag 12. The illustrated food bag 12 has a standard bag construction 13 comprising two side panels 14 and 16, each having a rectangular shape (although other geometries are certainly possible). The panels 14 and 16 can be made from a thermoplastic material or a blend of thermoplastic materials. The panels 14 and 16 are joined together along permanent side seams 18, a permanent bottom seam 20, and a recloseable top seam 22. The food bag 12 includes an opening 24 on one of its panels (panel 14 in the illustrated embodiment) for registration with the release valve 10 of the present invention.

Referring now to Figures 2A - 2D, the release valve 10 is shown in detail. The release valve 10 comprises a vent layer 30 and a cover layer 32. When installed on the food bag 12 (Figure 1 ), the vent layer 30 is the inner layer positioned closest to the bag panel 14 and the cover layer 32 is the outer layer positioned furthest therefrom. The vent layer 30 has an inner surface 34 and an outer surface 36, and the cover layer 32 has an inner surface 38 and an outer surface 40.

The vent layer 30 is made of a material which is pervious with respect to an expected fluid (e.g., air) and the cover layer 32 is made of material which is impervious to the expected fluid. The vent layer 30 can also be made of material which is pervious with respect to an expected gasses and impervious with respect to an expected liquids. ("Expected gasses" refers to gasses such as air and/or air mixed with gas from contents of the bag structure, and "expected liquids" refers to water and/or other liquids from the contents of the bag structure.) In the illustrated valve construction, baffle passageways 44 between the vent layer 30 and the cover layer 32 provide exit paths for gas being released through valve 10.

An adhesive area 50 on the inner surface 34 of the vent layer 30 attaches the release valve 10 to the bag structure 13. The adhesive area 50 covers the inner surface 34, except for an adhesive-free area 52 corresponding to the opening 24 in the food bag 12. (Figures 2B and 2C.) An adhesive area 54 between the vent layer 30 and the cover layer 32 attaches these layers together. In the illustrated embodiment, the adhesive area 54 comprises two bars occupying diametrically opposite arcs on the circular the surface 36, and the majority of the surface 36 is an adhesive-free area 56. (Figures 2B and 2D.) The adhesive-free area 56 extends to side edge portions of the valve 10, whereby the traverse baffling passageways 44 are formed for the escaping gas.

Referring now to Figures 3A - 3L, a method for mass-manufacturing a plurality of the food bags 12 according to the present invention is schematically shown. In this method, a plurality of the valves 10 is manufactured, a plurality of the bag structures 13 is manufactured separately and in a conventional manner, and the valves 10 are integrated into the structures 13 during the latter stages of bag production. While the illustrated schematic steps are shown with respect to a single row of valves 10 and/or bag structures 13, these steps can, of course, be performed simultaneously or intermittently to a plurality of rows for mass production purposes.

To manufacture the valves 10, a continuous web of cover material 60 is provided having an inner surface 62 and an outer surface 64. (Figure 3A.) A commercial indication, a name brand, a logo or other labeling indicia 66 is printed on the outer surface 64. (Figure 3B) An adhesive 68 is applied (e.g., printed) on the inner surface 62 of the cover material 60 in a pattern corresponding to the adhesive areas 54. (Figure 3C.) A continuous web of a vent material 70 having an inner surface 72 and an outer surface 74 is then positioned so that its outer surface 74 is adjacent the inner surface 62 of the cover material 60, whereby the adhesive 68 is positioned therebetween. (Figure 3D.)

An adhesive 76 is applied (e.g., printed) to the inner surface 72 of the vent material 70 in a pattern corresponding to the non-adhesive areas 52 in the valves 10. (Figure 3E.) A release liner 78 (e.g., polymeric film with a release coating) is positioned over the inner surface 72 of the vent material 70 so that the adhesive 76 is positioned therebetween. (Figure 3F.) The compilation of materials 60 and 70 is then die cut into squares corresponding to the overall circular shape of the valves 10. (Figure 3G.) The cuts do not extend through the release liner 78 whereby a web 80 comprising a plurality of the valves 10 temporarily attached to the release liner 78 (via the adhesive 76 or the adhesive area 50) is produced. (Figure 3H.) The web 80 can be shipped from the valve-manufacturing location to the bag- manufacturing location in, for example, roll form.

The bag structures 13 are separately mass-manufactured in a continuous strip wherein the bottom seam 20 of one bag structure 13 abuts against the top seam 22 of the adjacent downstream bag structure 13. (Figure 31). The valves 10 can be removed from the release liner 78, aligned with the openings 24 and secured to the bag structures 13 (Figure 3J). The removal, aligning, and securing step can be performed automatically (i.e., by a machine, not shown) or can be performed manually (i.e., by a person, not shown). The bag structures 13 are separated from each other by a severing device (not shown), either before or after the valve- securing step.

The cover material 60 (and the cover layer 32) can be made from polymer film materials such as polystyrenes, polyolefins, polyamides, polyesters, polycarbonates, polyvinyl alcohol, poly(ethylene vinyl alcohol), polyurethanes, polyacrylates including copolymers of olefins such as ethylene and propylene with acrylic acids and esters, copolymers of olefins and vinyl acetate, ionomers and mixtures thereof. The vent-to-cover adhesive 68 (and the adhesive areas 54) can be any suitable adhesive, such as a pressure-sensitive adhesive (e.g., acrylic- based, rubber-based, or silicone-based) or a curable-adhesive, such as a UV- curable adhesive. The vent material 70 (and the vent layer 30) can be made from nylon, polyolefins (e.g., polyethylene, polypropylene, ethylene butylene copolymers), polyurethanes, polyurethane foams, polystyrenes, plasticized polyvinylchlorides, polyesters, polyamides, cotton, or rayon. The vent material can be woven, non- woven, knitted and/or an aperatured (or perforated) film. The release liner 78 can be a sheet of paper or polymeric film having a release coating, such as a silicone release coating. The bag-to-vent adhesive 76 (and thus the adhesive area 50) are of particular relevance in the present invention. Generally, the adhesive 76 (and thus the adhesive area 50) can be any suitable adhesive, such as a pressure-sensitive adhesive (e.g., acrylic-based, rubber-based, or silicone-based) and, more particularly, a hot melt pressure-sensitive adhesive. An ultra-violet flourescing agent can be added to the adhesive 76 for production registration purposes. An important feature of the adhesive 76 is that it provide the desired attachment between the vent layer 30 and the bag structure 13. However, as is explained below, in certain embodiments of the invention, the adhesive 76 is also selected to minimize migration issues.

As is best seen by referring briefly back to Figures 2A - 2D, the bag-to-vent adhesive 50 occupies a region aligned with the non-adhesive area 56 (e.g., the baffle area) between the vent layer 30 and the cover layer 32. Thus, if the adhesive 50 were to migrate through the vent layer 30 in this region, adhesive could find its way into non-adhesive area 56, causing the cover layer 32 to "stick to" the vent layer 30 in this area 56. This sticking could constrict, or close, the passageways 44 through which the released gas flows to exit the valve 10, thereby inhibiting the valve's proper operation.

The migration of the bag-to-vent adhesive 50 to the non-adhesive area 56 could occur at many times during the life of the valve 10. For example, this migration could start during production of the valves 10, as early as when the adhesive 76 is applied to the vent material 70. Alternatively, migration could first begin during storage or shipment of the valves 10, even if these valves came off the production line migration-free. The present invention provides features which minimizes migration of the adhesive 50 and/or prevents sticking of the cover layer 32 in the non-adhesive area 56 upon such migration.

According to the present invention, the adhesive 76 is chosen so that its glass transition temperature (Tg), softening point, and viscosity are as high as possible. These three properties are believed to be the key properties affecting flow, or migration, through nonwoven vent material. An example of suitable hot melt pressure sensitive adhesive is H2187-01 hot melt PSA, which is sold by Ato Findley, Inc., of Wauwatosa, Wisconsin. When compared to conventional bag-to-vent adhesives, this adhesive has 8° C higher glass transition temperature (T_g), 30° F higher softening point, and 3000 cps higherviscosityat325° F reference temperature.

Also, measures can be taken to accelerate solidification of the adhesive 76 during production. For example, as shown in Figure 4, a roller 90 and/or a roller 92 encountering the adhesive 76 just after application can be chilled (e.g., cooled by a cooling water) to reduce the temperature of the adhesive 76 just after application. Additionally or alternatively, the application temperature of the adhesive 76 can be minimized and/or the adhesive coat weight can be minimized. The application of the adhesive 76 can also be altered to accelerate solidification and/or otherwise minimize migration issues. For an example, as shown in Figures 5A and 5B, the adhesive 76 can be pattern applied to the release liner 78 and then transferred to the inner surface of the vent material 70. (Compare Figures 3E and 3F wherein the adhesive 76 is applied to the vent material 70 and then the release liner 78 is placed thereover.)

For another example, as shown in Figures 6A and 6B, the adhesive 76 could be provided as a cold film in a transfer tape 94 and laminated to the vent material 70. In the illustrated embodiment, the adhesive 76 is positioned between a liner 96 and the release liner 78, with the liner 96 being removed prior to lamination and the release liner 78 remaining with the adhesive 76 after lamination. The tape 94 (including the liners 96 and 78) is die-cut to provide circular openings 98 corresponding to the non-adhesive areas 52 on the valves 10. Thus, in the web 80 (Figure 3H), the release liner 78 will include the openings 98 aligned with the non- adhesive areas 52 of the valves 10. Referring now to Figures 7 and 8, the valve 10 is modified to include a barrier layer 100 to prevent migration of the bag-to-vent adhesive 52 into the area 56. The barrier layer 100 can be positioned on the inner surface 34 of the vent layer 30 (Figures 7A - 7C) or the barrier layer 100 can be positioned on the outer surface 36 of the vent layer (Figures 8A - 8C). The barrier layer 100 can occupy an area which mirrors the shape of the adhesive area 50 (Figures 7B and 8B) or it can cover only the area crucial to forming the baffle passageways 44 (Figure 7C and 7D).

The barrier layer 100 can comprise an adhesive coated film which is laminated to the vent material 70 at the appropriate production stage. In the illustrated embodiment, the coated film would have to be die cut to include the proper doughnut shape (or hole) prior to this application. The adhesive of the coated film would need to adhere appropriately to the vent material 70, and the film of the coated film would need to allow adherence of the adhesive 76 thereto. The barrier layer 100 can comprise a flowable barrier material coated on the vent material 70 at the appropriate production stage. The barrier material can be a polymeric material. For example, the barrier layer can comprise a solvent based epoxy, an emulsion based urethane, an emulsion based acrylic, a curable (e.g., UV curable) acrylic or urethane, and/or a solvent based polyamide. A commercial example of a suitable barrier coating is Corkote IJ -1012' from Cork Industries, Jacksonville, Florida, which is an emulsion based acrylic coating.

The barrier material must, of course, have good adhesion, bonding, and/or connection with the vent material 70. To this end, the barrier material should be able to form a continuous/uniform solid layer (e.g., a lattice network) on the vent material 70, or if it penetrates through pores in the vent material 70, solidification should they should occur within (i.e., prior to exiting) the pores.

Material compatibility must be taken into consideration when selecting a barrier material. For example, if the vent material 70 has been surface treated, a different solvent may have to be used to disperse the barrier material to generate coating of different quality/morphology. For example, the vent layer 30 in the illustrated embodiment can comprise a non-woven polymer treated with a fluoropolymer to make it hydrophobic and/or water repellent. The barrier material dispersed in water/polar solvent would be inclined to form layer on top of the non- woven vent material 70, with minimum penetration into its open (or pored) structure. On the other hand, barrier material dispersed in non-polar solvent, such as toluene/hexane, would tend to fill up the pores.

Equipment availability and/or process requirements might also influence the selection of an appropriate barrier material. For instance, if the barrier coating is applied by a flexo-printing station (or other device which is designed to render a thin coatings), it might be quite difficult to have a continuous/uniform layer on top of vent material 70. In this case, it might be more realistic to choose a barrier coating that can be applied to penetrate the pores of vent material, followed by quick solidification. The barrier material must also withstand production and post-production handling. Specifically, for example, the barrier layer 100 should not be easily damaged or rubbed off of the vent material 70 (or the vent layer 30). Once solidified, the barrier coating should behave like a thermoset material, so that there will be little deformation/budge over long periods of time and upon environmental changes, such as fluctuation of temperature.

In addition to the barrier material appropriately bonding to the vent material 70, in certain valve designs the barrier material must also accommodate bonding of the neighboring adhesive (specifically, adhesive 76 in Figures 7A and 7B, and adhesive 68 in Figures 8A and 8B). Moreover, the barrier material should preferably be selected so that it possesses minimum adhesion to the cover material 60 (e.g., BOPP film).

With particular reference to Figures 7C and 8C, the barrier layer 100 can be applied as a coating in stripes running in the longitudinal direction of the vent material 70 (and thus perpendicular to the adhesive bars 68 in the illustrated embodiment). For example, the barrier layer 100 can be formed from a heat sealable material 102, with the heat being applied by rollers 104 to form the stripes. The barrier material 102 can be provided in form a film or can coated onto the vent material 70. The heat sealable material can comprise a polyethylene based, polyurethane based, polyester based, copolyester based, polyamide based, and/or amorphous polyolefin based polymer.

Referring now to Figures 9A - 9D, the valve 10 is shown modified to include a release layer 120 on the inner surface 38 of the cover layer 32. The release layer 120 can cover the entire inner surface 38 of the cover layer 32 (Figures 9A and 9B) or can cover only a region aligned with the non-adhesive area 56 (Figures 9C and 9D). In either case, should the bag-to-vent adhesive 50 migrate through the vent layer 30, the release layer 120 would prevent the cover layer 32 from sticking to vent layer 30 via the migrated adhesive. The release layer 120 can comprise silicone coatings (UV cured or otherwise), wax-based coatings, polyethylene or other low surface energy spray or liquid coatings, flouridated coatings, or any other low surface energy coating to which a migrating adhesive would not adhere.

The different anti-stick means disclosed can be combined when appropriate and/or when necessary. For example, as shown in Figures 10A - 10D, the valve 10 can include both a barrier layer 100 and a release layer 120. Also, for example, the release layer 120 can be used in conjunction with the adhesive 68 being transferred from the liner 78 and/or the adhesive 68 being provided by a transfer tape 94. One of the anti-stick means, or a combination of the anti-stick means, may be appropriate depending upon the intended application and other factors.

One may now appreciate that the present invention provides a valve design which allows economic and efficient mass-manufacturing, which can maintain integrity during shipping to distant locations, and/or which can be easily integrated with bag structures during latter phases of production. The release valve 10 can find application in food bags and, more particularly, in freezer bags where it is desired to release air to avoid freezer burn. However, the release valve 10 need not be used solely in food bags, but could find application in any flexible packaging container (for perishable and/or non-perishable items) wherein venting is necessary or desired. Although the invention has been shown and described with respect to certain preferred embodiments, it is evident that equivalent and obvious alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such alterations and modifications and is limited only by the scope of the following claims.

Claims

1. A release valve (10) for a food bag (12) comprising: a vent layer (30) having an inner surface (34) positionable over an opening (24) in a bag structure (13) of the food bag (12), the vent layer (30) being pervious with respect to an expected fluid; a cover layer (32) positioned over an outer surface (36) of the vent layer (30), the cover layer (30) being impervious with respect to the excepted fluid; a bag-to-vent adhesive area (50) positioned adjacent the inner surface (34) of the vent layer (30); an area (56) between the vent layer (30) and the cover layer (32) defining at least one passageway (44) through which the expected fluid would pass to exit the valve (10); and anti-stick means for preventing the bag-to-vent adhesive area (50) from causing the cover layer (32) to stick to the vent layer (30) in the area (56) and thereby block the passageway(s) (44).

2. A release valve (10) as set forth in the preceding claim, wherein a baffle area (54) is defined between the vent layer (30) and the cover layer (32), and wherein the baffle area (54) contains the passageway(s) (44).

3. A release valve (10) as set forth in the preceding claim, wherein the baffle area (56) defines at least two baffle passageways (44) in opposite directions.

4. A release valve (10) as set forth in the preceding claim, wherein the baffle area (56) defines only two baffle passageways (44) in opposite directions.

5. A release valve (10) as set forth in any of the preceding claims, wherein the vent layer (30) and the cover layer (32) are of substantially the same shape and size, and are coextensive with each other.

6. A release valve (10) as set forth in any of the preceding claims, wherein the vent layer (30) and the cover layer (32) are each of a substantially circular shape.

7. A release valve (10) as set forth in any of the preceding claims, wherein the vent layer (30) comprises a non-woven polymer fabric.

8. A release valve (10) as set forth in any of the preceding claims, wherein the cover layer (32) comprises a polymer film.

9. A release valve (10) as set forth in any of the preceding claims, further comprising a sealable area (52), the adhesive area (50) bordering the periphery of the inner surface (34) and surrounding, and sealing, the sealable area (52).

10. A release valve (10) as set forth in the preceding claim, wherein the sealable area (52) is sized for close registration with the opening (24) in the bag structure (13).

11. A release valve (10) as set forth in any of claims 1 - 10, wherein the anti-stick means comprises form the adhesive area (50) from an adhesive having a high glass transition temperature (Tg), a high softening point, and a high viscosity.

12. A release valve (10) as set forth in any of claims 1 - 10, wherein the anti-stick means comprises forming the adhesive area (50) from a transfer tape (94).

13. A release valve (10) as set forth in any of claims 1 - 11 , wherein the anti-stick means comprises barrier means for preventing migration of the adhesive area (50) through the vent layer (30).

14. A release valve (10) as set forth in the preceding claim, wherein the barrier means comprises a barrier layer (100).

15. A release valve (10) as set forth in claim 14, wherein the barrier layer (100) is positioned adjacent the inner surface (34) of the vent layer (30).

16. A release valve (10) as set forth in claim 14, wherein the barrier layer (100) is positioned adjacent the outer surface (36) of the vent layer (30).

17. A release valve (10) as set forth in any of claims 14 - 16, wherein the barrier layer (100) is in a pattern coextensive with the adhesive area (50).

18. A release valve (10) as set forth in any of claims 14 - 16, wherein the barrier layer (100) is in a pattern non-coextensive with the adhesive area (50).

19. A release valve (10) as set forth in the preceding claim, wherein the barrier layer (100) is in a pattern corresponding to the baffle passageways (44).

20. A release valve (10) as set forth in the preceding claim, wherein the barrier layer (100) is in a pattern comprising a pair of stripes.

21. A release valve (10) as set forth in any of claims 14 - 20, wherein the barrier layer (100) comprises a polymeric material.

22. A release valve (10) as set forth in the preceding claim, wherein the barrier layer (100) comprises a solvent based epoxy, an emulsion based urethane, an emulsion based acrylic, a curable acrylic or urethane, and/or a solvent based polyamide

23. A release valve (10) as set forth in any of the preceding claims, wherein the anti-stick means comprises a release means for releasing the cover layer (32) from the vent layer (30) should adhesive from the adhesive area (50) migrate through vent layer (30) into the area (56).

24. A release valve (10) as set forth in the preceding claim, wherein the release means (120) comprises a release layer (120) aligned with the area (56).

25. A release valve (10) as set forth in claim 24, wherein the release layer (120) is in a pattern coextensive with the inner surface (38) of the cover layer (32).

26. A release valve (10) as set forth in claim 24, wherein the release layer (120) is in a pattern non-coextensive with the inner surface (38) of the cover layer (32).

27. A release valve (10) as set forth in the preceding claim, wherein the release layer (120) is in a pattern corresponding to the passageway(s) (44).

28. A release valve (10) as set forth in any of claims 24 - 27, wherein the release layer (120) comprises a silicone-based, a wax-based, and/or a flouridated- based coating.

29. A web (80) comprises a plurality of the valves (10) set forth in any of the preceding claims and a release liner (64) to which the valves (10) are temporarily attached for selective removal therefrom for integration into the bag structure (13).

30. A web (80) as set forth in the preceding claim in a roll form.

31. A web (80) as set forth in either of the two preceding claims, wherein the adhesive area (50) temporarily attaches the valves (10) to the release liner (78).

32. A web (80) as set forth in any of the preceding three claims, wherein the release liner (78) includes openings (98) aligned with the non-adhesive areas (52) of the valves (10).

33. A method of making a plurality of the valves (10) set forth in any of claims 1-28, said method comprising the steps of: overlaying a vent material (70) and a cover material (60) so that an outer surface (74) of the vent material (70) is adjacent an inner surface (62) of the cover material (60); positioning an adhesive (76) on the inner surface (72) of the vent material (70) in a pattern corresponding to the adhesive areas (50); cutting the cover material (60) and the vent material (70) into shapes corresponding to the overall shape of the valves (10).

34. A method as set forth in claim 33, wherein said step of positioning the adhesive (76) on the inner surface (72) of the vent material (70) comprises the step of applying the adhesive (76) to the inner surface (72) of the vent material (70).

35. A method as set forth in the preceding claim, further comprising the step of overlaying a release liner (78) over the adhesive (76) on the inner surface (72) of the vent material (70).

36. A method as set forth in claim 33, wherein said step of positioning the adhesive (76) on the inner surface (72) of the vent material (70) comprises the steps of applying the adhesive (76) to a release liner (78); and transferring the adhesive (76) from the release liner (78) to the inner surface

(72) of the vent material (70).

37. A method as set forth in any of the preceding claims, wherein the vent material (70) passes over at least one roller (90, 92) during or immediately after said step of positioning the adhesive (76) on the inner surface (72) of the vent material (70), and wherein said roller(s) (90, 92) are chilled to accelerate solidification of the adhesive (76).

38. A method as set forth in claim 33, wherein said step of positioning the adhesive (76) on the inner surface (72) of the vent material (70) comprises the steps of supplying the adhesive (76) in the form a transfer tape (94) and attaching the transfer tape (94) to the inner surface (72) of the vent material (70).

39. A method as set forth in claim 33, further comprising the step of positioning a barrier layer (100) to prevent migration of the adhesive (76) through the vent material (70).

40. A method as set forth in claim 39, wherein the barrier layer (100) is positioned adjacent the inner surface (72) of the vent material (70).

41. A method as set forth in claim 39, wherein the barrier layer (100) is positioned adjacent the outer surface (75) of the vent material (70).

42. A method as set forth in any of claims 39 -41 , wherein the barrier layer (100) is in a pattern coextensive with the adhesive (76).

43. A method as set forth in any of claims 39 - 41 , wherein the barrier layer

(100) is a pattern non-coextensive with the adhesive (76).

44. A method as set forth in the preceding claim, wherein the barrier layer (100) is in a pattern corresponding to the baffle passageways (44) in the valves (10).

45. A method as set forth in the preceding claim, wherein the barrier layer (100) is in a pattern comprising a pair of stripes for each row of valves (10).

46. A method as set forth in any of the preceding claims 33 - 45, further comprising the step of positioning a release layer (120) between the cover material (60) and the vent material (70) so that the release layer (120) will be positioned between the cover layers (32) and the areas (56) in the valves (10).

47. A method as set forth in claim 46, wherein the release layer (120) is in a pattern coextensive with the inner surface (62) of the cover material (60).

48. A method as set forth in claim 46, wherein the release layer (120) is in a pattern non-coextensive with the inner surface (62) of the cover material (60).

49. A method as set forth in the preceding claim, wherein the release layer (120) is in a pattern corresponding to the passageway(s) (44) in the valves (10).

50. A method as set forth in any of claims 33 - 49, further comprising the step of positioning an adhesive (68) between the cover material (60) and the vent material (70) in a pattern corresponding to the areas (56) in the valves (10).

51. A food bag (12) comprising a bag structure (13) having an opening (24) and the release valve (10) set forth in any of claims 1 - 28.

52. A food bag (12) as set forth in the preceding claim, wherein the bag structure (13) includes a recloseable seam (22).

53. A food bag (12) as set forth in the preceding claim, wherein the bag structure (13) comprises a plurality of thermoplastic panels (14, 16) and wherein the opening (24) is on one of the panels (14).

54. A method of making a plurality of the food bags (12) set forth in any claims 51 - 53, said method comprising the steps of: manufacturing a plurality of the bag structures (13); separately manufacturing a plurality of the valves (10); aligning the valves (10) with the openings (24) in the bag structures (13) so that the sealable areas (52) will form sealed passageways between the vent layers (30) and the bag structures (13); securing the aligned valves (10) to the bag structures (13).

55. A method as set forth in the preceding claim, wherein the bag- manufacturing step is performed at a bag-manufacturing location and the valve- manufacturing step is performed at a different valve-manufacturing location.

56. A method as set forth in either of the two preceding claims, wherein said valve-manufacturing step results in a web (80) comprising a plurality of the valves (10) temporarily attached to a liner (78) for selective removal therefrom.

57. A method as set forth in the preceding claim, further comprising the step of removing the plurality of valves (10) from the liner (78) prior to said securing step.

58. A method as set forth in claim 57, wherein said removing step is performed automatically by a machine.

59. A method as set forth in claim 57, wherein said removing step is performed by hand.

60. A method as set forth in any of claims 54 - 59, wherein said aligning step and/or said securing step is performed automatically by a machine.

61. A method as set forth in any of claims 54 - 59, wherein said aligning step and/or said securing step is performed by hand.

62. A release valve (10) for a flexible container (13) comprising a vent layer (30), a cover layer (32), and means for preventing the sticking of the cover layer (32) to the vent layer (30).