WO1998046498A1

WO1998046498A1 - Gas-permeable foam in bag packaging system

Info

Publication number: WO1998046498A1
Application number: PCT/US1998/007741
Authority: WO
Inventors: George Teofilius Bertram
Original assignee: Sealed Air Corporation
Priority date: 1997-04-14
Filing date: 1998-04-14
Publication date: 1998-10-22
Also published as: AU7128498A

Abstract

A foam in bag packaging cushion (10, 20, 30, 40, 52, 60) comprising a sealed envelope that includes at least one panel (11, 27, 31, 41, 53, 64) formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors, and containing a foamable composition therein.

Description

GAS-PERMEABLE FOAM IN BAG PACKAGING SYSTEM

Field of the Invention

The present invention relates to foam-in- place packaging systems and in particular relates to the manufacture, structure, and use of gas-permeable bag cushion precursors that carry foamable compositions .

Background of the Invention

The present invention relates generally to foam-in-place packaging. Foam-in-place packaging has been well known and widely used as a protective packaging method for a number of years . The underlying technology is based upon the reaction between two (usually liquid) chemicals that form a solid polymer while at the same time generating a gaseous by-product. In particular, when isocyanate compounds react with polyols and water, the reaction produces both a urethane polymer ( "polyurethane" ) and carbon dioxide. Under proper conditions, the carbon dioxide generated by the reaction will bubble and disperse through the polymer as it hardens to thus form an expanded polymer foam that can be used as a protective material for packaging fragile objects. The process by which the liquid precursors mix as liquids and then expand as not-yet-hardened foam takes about 20-30 seconds thus making feasible its manipulation and use for packaging purposes .

In a first generation of foam-in-place packaging, objects to be protected were placed into containers (e.g. corrugated boxes), and wrapped or draped with a protective material such as a plastic sheet. Thereafter, the polyol and isocyanate were pumped from separate supplies, mixed, and then injected from a gun-like dispenser into the container. If the amount of injected mixture was appropriate, the resulting foam would essentially fill the interior of the container while surrounding the object to provide a custom package. Such relatively straightforward injection practices are still useful in many applications, and an updated injection device is disclosed, for example, in copending and commonly assigned application Serial No. 08/361,322 filed December 21, 1994 for "Hand Held Dispenser for Foamable Composi tions and Dispensing System. "

In a next generation of foam-in-place packaging, devices have been developed which concurrently produce plastic bags and fill them with the foamable mixture of polymer precursors . A packaging operator can simply drop one or more newly made bags into a container carrying an object to be packaged, and then close the container. The foam in the bag continues to generate and expand until it likewise fills the interior of the container while forming a custom- shaped cushion around the object packaged therein. Such bag making systems provide the advantage of injecting the foam into a bag that is immediately closed, rather than requiring the operator to manually dispense the foam. As is known to those familiar with such foamable chemicals, they tend to be extremely messy and, if not controlled properly, can cause problems which slow or stop the entire packaging process until the unwanted foam residue can be cleaned up. In more serious circumstances, the foam can even cause its handling machinery to break down leading to further additional delays. Examples of foam-in-place devices are described in a number of patents and copending applications that are commonly assigned with the present invention. These include inter alia, U.S. Patent Nos. 4,800,708; 4,854,109, 4,938,007; 5,027,583; 5,139,151 and 5,376,219 and pending applications Serial Nos. 08/121,751, filed September 15, 1993 and 08/514,010 filed August 11, 1995. These patents and applications are incorporated entirely herein by reference .

As noted above, because foam-in-bag cushions are typically formed by mixing two precursors that react to both form a polymer and generate a gas, some means must be provided to vent the gases to and from the bag as the foam rises. To date, this has been carried out by providing some sort of physical opening in the bag. For example, certain versions of the devices described in the above-referenced patents and applications refrain from sealing a defined portion of a transverse edge of a bag. The resulting unsealed portion provides a vent through which gases can travel. Other devices (e.g. U.S. Patent No. 4,999,975 to Willden et al . ) use various interrupted sealing patterns rather than linear seals in an attempt to provide a vented bag that nevertheless prevents foam from leaking.

More recent devices incorporate a spiked roller over which the plastic film material passes as the bag is being formed. The spiked roller punctures the bag to provide vent holes that are sufficient to allow gases to travel, but which tend to capture plastic foam. Copending application Serial No. 08/626,981 filed October 2, 1996 to Bertram et al . for "Foam Cushioning Panels for Packaging Purposes" describes such a spiked roller, and is incorporated entirely herein by reference.

Nevertheless, such systems, though operationally well developed, still offer some disadvantages. For example, the chemical reaction that drives the foam formation also tends to generate significant heat. This in turn can cause water vapor to condense and give the appearance of steam escaping from the vent opening. Second, the direct venting of the gases can produce an odor that some find undesirable or offensive. Third, the necessity of keeping the foam from escaping requires the ventilation openings to be very small and thus somewhat less efficient than they could be if they were larger. If the vent openings are too large, however, foam that reaches a vent opening can exit along with the gases, causing a potential problem with the packaged goods. In particular, rising foam tends to be quite sticky.

Fourth, in order to reduce the risk that foam will escape, the bags are usually made from an excess- - and thus wasteful--amount of plastic film material.

Finally, because the bags are typically used in custom orientations- -indeed, such is their advantage- -the vent opening may wind up in position through which the gases travel less efficiently, or even not at all.

Therefore, the need exists for a vented foam- in-bag cushion through which gases can successfully travel without allowing foam to escape, without using excess plastic film, and while reducing odors.

Object and Summary of the Invention

Therefore, it is an object of the present invention to provide a foam-in-bag cushion which allows gas to travel without rupturing the bag, without allowing foam to escape, and without a specified vent opening.

The invention meets this object with a foam- in-bag packaging cushion comprising a sealed envelope that includes at least one panel formed of a material that is gas permeable but prevents passage of foam or foam precursors, and that contains a foamable composition therein.

In another aspect, the invention comprises a packaging cushion formed of two overlying sheets of plastic film material, four closed edges at the perimeter of the sheets that together with the sheets define a sealed envelope, with a portion of at least one of the sheets being formed of a material that is gas permeable, but prevents passage of foam or foam precursors, and a foamable composition inside the closed envelope; In a third aspect, the invention is a method of making foam-in-place packaging cushions that include closed edges without specific vent openings.

In yet another embodiment, the invention comprises a package comprising a shipping container and an item in the container that requires protection, and a foam-in-bag packaging cushion in the container.

The benefits of the invention include: more reliable and consistent venting; a reduction in generated odors; a reduction in visible steam; a reduction in vaporized isocyanate levels; prevention of foam leakage; prevention of foam precursor leakage; a fuller bag; and a savings in bag material (because less margin of error is required to provide and protect the vent) . The foregoing and other objects, advantages and features of the invention, and the manner in which the same are accomplished, will be more readily apparent upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings, which illustrate preferred and exemplary embodiments, and wherein:

Brief Description of the Drawings

Figure 1 is a perspective view of a packaging cushion according to the present invention; Figure 2 is a perspective view of a second embodiment of a packaging cushion according to the present invention;

Figure 3 is a perspective view of a third embodiment of a packaging cushion according to the present invention; Figure 4 is a perspective view of a fourth embodiment of the invention;

Figure 5 is a perspective view of a shipping container and items to be packaged therein and to be protected by a foam-in-bag cushion according to the present invention; and

Figure 6 is a partially exploded perspective view of a fifth embodiment of the invention.

Detailed Description The invention is a foam-in-bag cushion, a first embodiment of which is illustrated at 10 in Figure 1. It will be understood that the bags 10 are shown in stylistic, pillow-shaped fashion. In use, of course, the bags take the orientation of their surroundings--indeed such is their advantage- -and typically rarely resemble the idealized illustrations.

The cushion 10 comprises a sealed envelope that includes at least one panel, illustrated as the cross-hatched portion 11 in Figure 1, formed of a material that is gas permeable but that prevents substantial passage of foam and foam precursors and containing a foamable composition 12 therein. As used herein, the term "sealed" carries its ordinary dictionary meaning; i.e. to close or make secure against access, leakage, or passage by a fastening or a coating.

Stated in the alternative, and using Figure 2 as an illustration, the packaging cushion of the invention is broadly designated at 20, and is formed of two overlying sheets 21 and 22 of plastic film material. Four closed edges 23, 24, 25 and 26 at the perimeter of the sheets 21 and 22 together with the sheets define the sealed envelope 20.

A portion 27 of at least one of the sheets (21 in Figure 2) is formed of a material that is gas permeable but that prevents the substantial passage of foam and foam precursors. A foamable composition 30 is inside the closed envelope 20 of the second embodiment. Although materials that are impervious to liquids and solids are quite useful, and often preferred, the invention is not limited to such impervious materials. The generally desired characteristic (in all embodiments) is that the gas-permeable material form a barrier to both foam precursors and to the rising foam they form. In the preferred embodiments, the remaining portions of the sheets 21 and 22 are formed of materials that are impervious to gases, liquids and solids (and that can also withstand the exotherm of the foaming chemicals) , and are most preferably formed of thermoplastic materials such as polyolefins, polyesters, polyvinyl chloride, acrylic polymers, polycarbonate, nylon, fluoropolymers, and polyurethanes . Such thermoplastic polymers have a number of advantages including low cost, appropriate strength, and the capability to be heat sealed.

Antistatic agents or coatings can also be incorporated into the permeable and impermeable portions of the bags in any manner that does not otherwise interfere with the other desired properties of the bag. Such agents or coatings are generally familiar to those of ordinary skill in the plastic film arts.

In preferred embodiments, the gas permeable portion 27 (or 11 in Figure 1) is selected from the group consisting of nonwoven bonded polyolefin fibers, microporous polytetrafluoroethylene (PTFE) , textile fabrics (e.g. woven polyolefins such as those from Synthetic Industries in Gainsville, GA) , and porous papers, such as surgical grade kraft paper. Furthermore, the type and amount of permeable material used is sufficient to allow enough gas to escape quickly enough to provide and maintain a proper foam structure . Interestingly enough, a bag's vent--whether permeable material or a simple opening- -also serves to allow air to enter the bag after the foam finishes rising and begins to cool. Allowing sufficient air to reach the bag's interior as the foam cools and cures helps prevent the foam from shrinking.

Presently preferred gas-permeable materials include spunbonded polypropylene meltblown composite nonwoven materials such as the several ULTRAFLO™ materials from BBA Nonwovens, Old Hickory, Tennessee.

The product melts at about 135°C, making heat sealing a reasonable operation, and also exhibits good liquid hold-out characteristics.

Other porous materials can include the various microporous membrane materials which are generally well-known to those of ordinary skill in these arts, but are often more expensive than the more common materials such as paper or nonwoven polyolefins . Thus, the choice of their use (or nonuse) in the present invention tends to be a cost consideration rather than a structural one .

Appropriate grades of paper are also useful for the permeable portion of the cushion. Such papers are generally well recognized and widely used in the medical arts, particularly for gas sterilization pouches and similar items which must provide both gas permeability and a barrier to solids, liquids, and objects .

As noted above, useful gas permeable materials are at least impervious to rising foam.

Preferred materials are impervious to both foam and foam precursors, and the most preferred gas-permeable materials are impervious to liquids and solids.

Additionally, the gas-permeable material can incorporate (e.g. chemically or as a coating) absorbants, or other compositions for various purposes as may be desirable or necessary. Absorbants expected to be useful include stearic acid, citric acid, charcoal, and silica gel. The organic acids have the added effect of helping to neutralize the pH-basic nature of any residual or escaping foam precursors . It also will be understood that when the bags of the present invention are referred to as being formed from "two sheets," such includes a center-folded sheet that forms two overlying sheets, as well as tube stocking which when flattened likewise takes the same form as two overlying sheets. The bags can also include other folds or gussets as may be desired for other purposes.

Thus, depending upon the most convenient method of manufacturing the bag that forms the packaging cushion, the closed edges can comprise several variations of other folded edges or sealed (typically heat sealed) edges. For example, when the bag 20 is formed from two separate webs of plastic film material, all four of the closed edges 23, 24, 25 and 26 can comprise sealed edges.

Alternatively, if a tube stock is used to form the bag, flattening the tube provides two closed edges in the form of folds, and the other two edges (generally transverse to the folds) , can be sealed edges.

In another embodiment, a single sheet can be center-folded onto itself and then sealed with one longitudinal seal parallel to the fold, and two transverse seals perpendicular to the fold. The advantages and disadvantages of each type of bag structure are generally thoroughly discussed in the aforementioned patents and applications that have been incorporated herein by reference, and will not be discussed in further detail herein, other than to illustrate particular features of the invention.

As illustrated in the drawings, the gas permeable panel can be incorporated in the cushion in a number of variations, including equivalents to those illustrated herein.

For example, in Figure 2, the permeable portion 27 extends along one of the closed edges 24 and more particularly extends entirely along the closed edge 24 and is bordered by two of the other opposite closed edges 23 and 25.

Figure 3 illustrates another embodiment designated at 30 in which the gas permeable portion 31 forms a folded edge of the bag 30 and the gas permeable portion 31 further extends from the folded edge to form a gas permeable portion on each face of the sealed envelope 30 forming the bag.

Figure 4 illustrates a fourth embodiment 40 in which the gas permeable portion 41 is noncontiguous with all of the four closed edges.

In Figures 1-5, both the bags and the gas permeable portions have been shown as being generally rectangular. It will be understood, of course, that the illustrated shape is not limiting of the invention, and that other geometries can be selected for either the bag or for the gas permeable portion without departing from the scope of the claims or their equivalents . Figure 5 illustrates that in another embodiment the invention comprises a package comprising a shipping container 50, typically in the form of a rectangular solid container formed of corrugated board, one or more items illustrated as the wine glasses 51 that require protection from physical damage, and a foam-in-bag packaging cushion 52 in the container 50 with the items 51. The cushion 52 comprises at least one panel 53 formed of a material that is gas permeable, but that prevents substantial passage of foam and foam precursors.

In addition to the benefits already mentioned, the use of a vent strip of gas-permeable material, rather than a physical vent opening, permits the user to fill the entire bag with foam. In contrast, prior bag designs that incorporate openings generally require the use of additional film near the opening and spaced from the rising foam, to prevent the rising foam from reaching the opening and escaping.

Another embodiment of the invention is illustrated in Figure 6 in which the cushion is broadly designated at 60. As illustrated in Figure 6, one portion of the bag is formed of a first sheet 61 with physical openings illustrated as the slots 62 therein, a second sheet 63 that similarly carries openings 62, and a panel of the gas permeable material 64 secured between the first and second sheets 61 and 63. This particular embodiment offers the advantage of providing a method for including the permeable material without heat sealing, or indeed any other physical seal between the permeable material and the remainder of the cushion material. For example, and referring again to Figure 6, the sheet 64 of permeable material can be made slightly smaller than the overlying sheets 61 and 63. In such a circumstance, the top sheet 63 could be sealed to the lower sheet 61 (as oriented in Figure 6) with the sheet of permeable material 64 sandwiched therebetween. It will thus be understood that the sheet of permeable material 64 would not be required to be sealed to anything else, but would be held in place by sheets 61 and 63. The embodiment illustrated in Figure 6 also provides the opportunity for the sheet 64 to be formed of an even wider variety of materials because it eliminates the necessity of the permeable material sheet 64 being heat sealable or even adhesively sealable to the remainder of the cushion 60. It will be understood from the embodiment of Figure 6 that a variety of similar pouches and the like could be formed using the basic structure illustrated in Figure 6 and claimed herein. Similarly, the nature of the openings 62 becomes much less critical because they no longer need to serve to block foam or foam precursors as such openings are required to do in more conventional foam- in-bag cushion structures.

In the drawings and specification, there have been disclosed typically preferred embodiments of the invention, and although specific terms have been employed, they have been used in a generic and descriptive sense only, and not for purposes of limitation, the scope of the invention being set forth in the following claims.

Claims

CLAIMS :

1. A foam in bag packaging cushion comprising a sealed envelope that includes at least one panel formed of a material that is gas-permeable, but prevents substantial passage of foam and foam precursors, and containing a foamable composition therein.

2. A packaging cushion according to Claim 1 wherein the type and amount of permeable material in said panel is sufficient to allow enough gas to escape quickly enough to provide and maintain a proper foam structure.

3. A packaging cushion according to Claim 1 wherein the remainder of said sealed envelope other than said permeable portion is formed of a material that is impervious to gases, liquids, and solids.

4. A packaging cushion according to Claim 3 wherein the remainder of said envelope is formed of a material selected from the group consisting of: paper, polyolefins, polyesters, polyvinyl chloride, acrylic polymers, polycarbonate, nylon, fluorocarbons, and polyurethanes .

5. A packaging cushion according to Claim 1 wherein said gas-permeable panel is selected from the group consisting of: nonwoven bonded polyolefin fibers, microporous polytetrafluoroethylene, textile fabrics, and porous paper.

6. A packaging cushion according to Claim 1 wherein said gas-permeable panel comprises a web of nonwoven bonded polypropylene fibers and the remainder of said sealed envelope comprises polyethylene.

7. A packaging cushion according to Claim 1 wherein said gas-permeable panel comprises: a first sheet with vent openings therein; a second sheet with vent openings therein; a sheet between said first and second sheets and formed of a material that is permeable to gases but prevents substantial passage of rising foam; and means for securing said gas permeable sheet between said first and second sheets.

8. A packaging cushion according to Claim 7 wherein said securing means comprises a seal between said first and second sheets.

9. A foam in bag packaging cushion comprising a sealed envelope formed of a material that is gas-permeable, but prevents substantial passage of foam and foam precursors, and containing a foamable composition therein.

10. A packaging cushion comprising: two overlying sheets of plastic film material; four closed edges at the perimeter of said sheets that together with the sheets define a sealed envelope; a portion of at least one of said sheets being formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors ; and a foamable composition inside said closed envelope .

11. A foam in bag packaging cushion according to Claim 10 wherein said gas-permeable material is impervious to liquids and solids.

12. A packaging cushion according to Claim 10 wherein the remainder of said sheets other than said permeable portion are formed of a material that is impervious to gases, liquids, and solids, and that will withstand the exotherm generated by the reaction of said foamable composition.

13. A packaging cushion according to Claim 12 wherein the remainder of said sheets are formed of a material selected from the group consisting of: paper, polyolefins, polyesters, polyvinyl chloride, acrylic polymers, polycarbonate, nylon, fluorocarbons, and polyurethanes .

14. A packaging cushion according to Claim 10 wherein the type and amount of permeable material in said gas-permeable portion is sufficient to allow enough gas to escape quickly enough to provide and maintain a proper foam structure.

15. A packaging cushion according to Claim 10 wherein said four closed edges comprise sealed edges.

16. A packaging cushion according to Claim 10 wherein said four closed edges comprise two folded edges and two sealed edges .

17. A packaging cushion according to Claim 10 wherein said four closed edges comprise one folded edge and three sealed edges.

18. A packaging cushion according to Claim 10 wherein said gas-permeable portion comprises the entirety of one of said overlying sheets.

19. A packaging cushion according to Claim 10 wherein both of said sheets are formed entirely of said gas-permeable material.

20. A packaging cushion according to Claim 10 wherein said gas-permeable portion comprises a panel that extends along one of said closed edges.

21. A packaging cushion according to Claim 20 wherein said gas-permeable panel extends entirely along one of said closed edges and is bordered by two other opposite closed edges.

22. A packaging cushion according to Claim 10 wherein at least one closed edge is a folded edge and wherein said gas-permeable portion forms said folded edge .

23. A packaging cushion according to Claim

22 wherein said gas-permeable portion forms one said entire folded edge, and extends from said folded edge to form a gas-permeable portion on each face of said envelope .

24. A packaging cushion according to Claim

10 wherein said gas-permeable portion comprises a panel that is noncontiguous with all of said four closed edges .

25. A packaging cushion according to Claim 10 wherein said gas-permeable portion comprises a strip extending across said cushion.

26. A packaging cushion according to Claim 10 wherein said gas-permeable portion is selected from the group consisting of : nonwoven bonded polyolefin fibers, microporous polytetrafluoroethylene, textile fabrics, and porous paper.

27. A packaging cushion according to Claim 10 wherein said gas-permeable portion comprises a web of nonwoven bonded polypropylene fibers, and the remainder of said sheets comprise polyethylene.

28. A method of making foam-in-place packaging cushions that include closed edges, the method comprising: placing a foamable composition between two plastic sheets in overlying adjacent relationship, at least one of said sheets having a portion formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors; and closing the edges of the overlying sheets to form a sealed envelope with the foamable composition therein.

29. A method according to Claim 28 and further comprising the step of placing two separate sheets in overlying relationship prior to the step of placing the foamable composition therebetween, and wherein the step of closing the edges comprises sealing all four edges to form the sealed envelope.

30. A method according to Claim 28 and further comprising the step of folding a single sheet into a face-to-face relationship that defines one closed edge with the fold prior to the step of placing the foamable composition therebetween, and wherein the step of closing the edges comprises sealing the remaining three edges to form the sealed envelope.

31. A method according to Claim 28 wherein the two plastic sheets comprise a tube, and wherein the step of closing the edges comprises sealing the transverse open ends of the tube to form the sealed envelope .

32. A package comprising: a shipping container; an item in said shipping container that requires protection from physical damage, and a foam in bag packaging cushion in said container with said item, said cushion comprising at least one panel formed of a material that is gas- permeable, but that prevents substantial passage of foam and foam precursors .

33. A package according to Claim 32 wherein said shipping container comprises a rectangular solid container.

34. A package according to Claim 32 wherein said shipping container is formed of corrugated board.

35. A package according to Claim 32 wherein the remainder of said cushion other than said permeable portion is formed of a material that is impervious to gases, liquids, and solids.

36. A package according to Claim 35 wherein the remainder of said cushion is formed of a material selected from the group consisting of: polyolefins, polyesters, polyvinyl chloride, acrylic polymers, polycarbonate, nylon, fluorocarbons, and polyurethanes.

37. A package according to Claim 32 wherein the type and amount of permeable material in said gas- permeable panel is sufficient to allow enough gas to escape quickly enough to provide and maintain a proper foam structure.

38. A package according to Claim 32 wherein said gas-permeable portion is selected from the group consisting of: nonwoven bonded polyolefin fibers, microporous polytetrafluoroethylene, textile fabrics, and porous paper.

39. A package according to Claim 32 wherein said gas-permeable panel comprises a web of nonwoven bonded polypropylene fibers, and the remainder of said bag comprises polyethylene.

40. A packaging cushion comprising: two overlying sheets of plastic film material; four closed edges at the perimeter of said sheets that together with the sheets define a sealed envelope; one of said sheets being formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors ; and a foamable composition inside said closed envelope .

41. A packaging cushion according to Claim

40 wherein said gas-permeable material is impervious to liquids and solids.

42. A packaging cushion according to Claim

40 wherein said gas-permeable sheet comprises a web of nonwoven bonded polypropylene fibers, and the other of said sheets comprises polyethylene.

43. A packaging cushion comprising: two overlying sheets of plastic film material ; four closed edges at the perimeter of said sheets that together with the sheets define a sealed envelope; one of said sheets including a panel, extending along one of said closed edges, and formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors; and a foamable composition inside said closed envelope .

44. A packaging cushion according to Claim

43 wherein said gas-permeable panel extends entirely along one of said closed edges and is bordered by two other opposite closed edges .

45. A package according to Claim 43 wherein said gas-permeable panel comprises a web of nonwoven bonded polypropylene fibers, and the remainder of said sealed envelope comprises polyethylene.

46. A packaging cushion comprising: two overlying sheets of plastic film material; four closed edges at the perimeter of said sheets that together with the sheets define a sealed envelope, at least one of said closed edges comprising a folded edge; a portion of one at least one of said sheets being formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors, with said gas-permeable portion forming said folded edge; and a foamable composition inside said closed envelope .

47. A packaging cushion according to Claim 46 wherein said gas-permeable portion forms one said entire folded edge, and extends from said folded edge to form a gas-permeable portion on each face of said envelope .

48. A packaging cushion according to Claim 46 wherein said gas-permeable portion comprises a web of nonwoven bonded polypropylene fibers, and the remainder of said sealed envelope comprises polyethylene .

49. A packaging cushion comprising: two overlying sheets of plastic film material ; four closed edges at the perimeter of said sheets that together with the sheets define a sealed envelope; a portion of at least one of said sheets being formed of a material that is gas-permeable, but that prevents substantial passage of foam and foam precursors and that is noncontiguous with all of said four closed edges; and a foamable composition inside said closed envelope .

50. A packaging cushion according to Claim 49 wherein said gas-permeable portion comprises a web of nonwoven bonded polypropylene fibers, and the remainder of said sealed envelope comprises polyethylene .