WO2006024937A1

WO2006024937A1 - Moisture permeable container

Info

Publication number: WO2006024937A1
Application number: PCT/IB2005/002610
Authority: WO
Inventors: Willem Morkel Van Der Westhuizen; Cornelius Uys Lourens Fick
Original assignee: Van Der Westhuizen Willem Mork; Cornelius Uys Lourens Fick
Priority date: 2004-09-03
Filing date: 2005-09-05
Publication date: 2006-03-09

Abstract

This invention relates to a moisture-permeable container (10) and to a method of manufacture thereof. The container includes a first portion (20) and a second portion (60), the first portion (20) comprising a first layer (30) of non-permeable material; a second layer (40) adhered to a peripheral zone of an inner surface of the first layer (30) to form a primary seal (100); and a third layer (50) of a non-permeable material which is adhered to the first layer (30) by the second layer (40) to form a secondary seal (110). The second portion (60), which may be formed from one or more layers, is secured to the outer edge of the first portion (20) to form a container seal, either by being sealed directly to the second layer (40) or directly to the third layer (50), depending on whether the third layer covers the second layer entirely. The container (10) optionally contains a desiccant (70) located within a pocket (80) formed between the third layer (50) and the second portion (60) and defined by the container seal.

Description

MOISTURE PERMEABLE CONTAINER

BACKGROUND OF THE INVENTION

This invention relates to moisture permeable containers and to a method of manufacture thereof.

Containers that absorb water vapour, water, liquids and the like are well known in the art. Generally, these containers have packaging consisting of one or more micro- porous materials formed from fibrous or film products sealed together at the edges of the packaging. The packaging material usually encapsulates a desiccant material, such as silica gel, anhydrous calcium chloride or activated clay. The volume of water or water vapour absorbed by the container is generally determined by the absorbent capacity of the desiccant material contained within the container.

Conventional desiccant containers, and other types of breathable containers, are usually formed by either using adhesives, coatings and/or laminated materials in order to incorporate the breathable material into the design. As a result, the strength of the container is directly linked to the strength of the adhesives and/or coatings and/or laminated materials and the breathable materials, and especially the way that these different materials are incorporated into the container with the breathable material.

There are, however, significant problems with the production of packaging materials for these containers and their use with specific types of desiccant materials. During the production of conventional laminated packaging materials, at least one side of the packaging material is generally coated with an adhesive. Films laminated with adhesives do not form a strong bond between the layers, which is desirable for desiccant packaging. In addition, because coated films are more expensive than uncoated films, packaging materials formed using coated films tend to be more expensive than those formed from uncoated films.

It is also possible to seal the moisture permeable material directly with a conventional laminated packaging material. This provides a better product than those described above, but still poses problems when the container is exposed to handling or drop tests, as the container is likely to leak or burst. The moisture permeable material also does not offer the same quality of conventional packaging. Strength and stability in a container is important to ensure a high quality desiccant product that will not only protect the contents of the container but will also retain liquid inside the packaging material.

Problems with current breathable and desiccant containers are also linked to the properties of the commercially available breathable packaging materials, such as Tyvek™, GORE-TEX™ (Gore & Co. Gmbh), SKY AIR™ and Celgard™. These materials are designed to be porous and generally do not give much stability to a breathable container (both to the seal and structure). In conventional breathable containers, the breathable materials are incorporated in some or other form (for example, laminated, coated, glued, sealed to a laminate or the like) in the structural seals that form the breathable container. These do not offer the same strength and stability offered by containers extensively used in the conventional retail packaging industry, which are formed with high seal strength materials such as polyethylene, polypropylene and PET/LDPE laminates and so forth. These conventional packaging materials offer high seal strengths, wide conversion parameters and good strength and product stability.

The applicant has therefore identified a need for manufacturing a moisture permeable container that will provide high seal strengths and container stability. SUMMARY OF INVENTION

According to a first embodiment of the invention, there is provided a moisture permeable container including a first portion and a second portion adhered to each other so as to form an enclosed pocket, wherein the first portion includes: a first layer of a moisture permeable material; a second layer of material covering at least a peripheral zone on at least htree edges of an inner surface of a first layer so as to form a first or primary seal; and a third layer of a moisture permeable material which is adhered to the first layer by the second layer, so as to form a second or secondary seal; and wherein the second portion includes at least a fourth layer of material which is adhered to at least three edges of the first portion so as to form a third or container seal and wherein the container seal does not overlap with at least an inner portion of the secondary seal.

The third layer may optionally only partially overlap the second layer on one or more edge of the first portion, so that a portion of the second layer on one or more of the edges of the first portion is adhered directly to the second layer.

The desiccant container may include a fifth layer of a removable, nonporous material. The fifth layer may be located on an outer surface of the first layer. The fifth layer may be adhered to the first layer by means of a low-strength adhesive that permits the fifth layer to be peeled off the first layer.

The fourth layer may be a nonporous material. Alternatively, the second portion of the container may include two or more layers. For example, the second portion may include three layers that are similarly joined as the layers of the first portion, so as to form a container where both the first and second portions are capable of absorbing moisture. The moisture permeable material of the first layers may be a micro-porous, porous, fibrous, and/or monolithic material.

In one embodiment, the first layer is a fibrous material such as paper and more particularly, a wet strength paper and/or a bond paper.

In another embodiment, the first layer is a microporous material formed from polyethylene or polypropylene, such as a polyethylene spun-bonded paper or a polypropylene-based film.

The material of the first layer may have a higher sealing temperature than the material of the second layer.

The material forming the second layer may be a porous; fibrous and/or non-breathable material. The material, however, is typically a non-breathable material. The material is preferably a high seal-strength material. Suitable materials for the second layer are polyethylene, polypropylene, polyester, polyolefin, monolithic polymer and uncoated poly-olefinic polyethylene materials.

The second layer may be heat sealed to the first layer.

In one embodiment, the second layer may be formed form a sheet having a zone that is punched, cut out or otherwise rendered moisture permeable prior to or at the time of sealing to the first layer, so that moisture is able to pass from the first layer through to the third layer.

The moisture permeable material of the third layer may be a micro-porous, porous or monolithic material, such as a monolithic polyester material. The third layer preferably does not permit the passage of water molecules in liquid form therethrough.

The fourth layer may be any suitable non-breathable material that can be joined by the second layer to the first layer. The second portion may be formed from folding the first portion into two, thereby forming the first and second portions.

The container may include a desiccant material such as a hygroscopic desiccant substance, silica gel, bentonite clay, sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, attapulgite clay, magnesium sulfate, starch, clay and/or a super absorbent or mixtures thereof.

The desiccant material is preferably located between the third layer of the first portion and the second portion.

An absorption indicator may be provided for indicating the degree of water absorption by the desiccant material.

The absorption indicator may include visual indicating means, such as a colouration or discolouration indicating means.

One or more of the layers may include a substantially transparent portion for viewing the absorption indicator.

The desiccant container may include a fragrance. The fragrance may be incorporated in one or more of the layers of the container, or may be included in the desiccant material.

According to a second embodiment of the invention, there is provided a method of manufacturing a moisture permeable container, the method including the steps of: adhering a second layer of a high-strength adhesive material to a peripheral zone of a first layer of a moisture permeable material, the second layer covering only the peripheral zone of the first layer, thereby forming a first seal joining the first and second layers; adhering a third layer of a moisture permeable material to at least a portion of the second layer, thereby forming a second seal joining the first, second and third layers; and adhering the peripheral edges of a fourth layer to an exposed zone of the second layer or to an outer edge of the third layer, thereby forming a third seal, whereby the third seal does not overlap the second seal completely.

The first and second seals may be formed consecutively or simultaneously.

The third seal may be stronger than the second seal.

A desiccant substance substantially as described above may be inserted into a pocket formed between the third and fourth layers, whereafter the unsealed portion of the fourth and second layers may be sealed.

The seals may be formed by heat sealing, bonding, laminating, gluing or the like. The first, second, third and fourth layers may be substantially as described above. The layers may form first and second portions of the desiccant container as described above.

A fifth layer of a non-breathable material may also be removably adhered to an outer portion of the first layer.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described by way of example with reference to the accompanying schematic drawings.

Figure 1: shows a sectional side view of a first embodiment of a container in accordance with the invention;

Figure 2: shows an exploded view of a portion of the container of Figure 1 showing the first and second sealing areas;

Figure 3: shows a front view of the inner side of the first portion of a container of Figures 1 and 2; Figure 4. shows a sectional side view of a second embodiment of a container in accordance with the invention;

Figure 5: shows a sectional side view of a third embodiment of a container in accordance with the invention;

Figure 6: shows a sectional side view of a fourth embodiment of a container in accordance with the invention; Figure 7: shows a sectional side view of a fifth embodiment of a container in accordance with the invention;

Figure 8: shows a front view of two alternative methods for aligning the first and second portions of a container in accordance with the invention; and

Figure 9: shows a sectional side view of a sixth embodiment of a container in accordance with the invention.

Figure 10: shows a sectional side view of a sixth embodiment of a container in accordance with schematic drawings.

Figure 11 : shows an exploded view of the container of Figure 10.

Figure 12: shows the view of Figure 11 , but also including layer 4 forming the second portion.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a container having first and second portions which are at least partially sealed together to form a pocket. At least one, and optionally both, of the first and second portions is moisture permeable to allow water vapour to be absorbed within the pocket, by for example, dessicant material. The first portion is composed of at least three layers, and the second portion has at least one layer, but optionally two or more layers.

Figure 1 shows a first embodiment of a desiccant container 10. The container 10 is formed from a first portion 20 consisting of a first layer 30, a second layer 40 and a third layer 50, and a second portion 60 consisting of only one layer. A desiccant material 70 is contained within a pocket 80 formed by the first 20 and second 60 portions. A fifth layer 90 is removably attached to an outer surface of the first layer 30.

The first layer 30 is formed from any suitable moisture permeable material, which may be breathable or monolithic. For example, the material may be porous and/or micro- porous material, such as Celgard™ (Hoechst Celanese Corporation), GORE-TEX™ (Gore & Co. GmBH) and Tyvek™ (E. I. DuPont). Preferably, the micro-porous material is a polyethylene or polypropylene-based micro-porous layer, and more preferably a polyethylene spun-bonded paper such as Tyvek™1059B or 1037B, or a polypropylene- based film, such as GDT II, manufactured by San Ai Ltd of Osaka, Japan.

The second layer 40 is generally a non-breathable material such as polyethylene.

The third layer 50 is preferably a micro-porous breathable polyethylene material, such as Tyvek™, GORE-TEX™, Celgard™, Espoir™, or SKY AIR™.

The fourth layer 60 is preferably a laminated polyester and polyethylene sheet, with the polyethylene surface 62 facing inwards and the polyester surface facing outwards.

The fifth layer 90 is preferably a non-breathable easy peel sheet that could be peeled off the first layer 30 to activate the container 10 by allowing it to absorb vapour.

Figure 2 shows an enlarged view of a portion of the container 10 of Figure 1 , showing the different seals that are formed when manufacturing the container 10.

The first and second layers, 30 and 40 respectively, are laminated, joined and/or sealed to each other to form a primary seal 100. The primary seal 100 covers some, but not all of the first layer 30. In this particular embodiment, the second layer 40 covers only the edges of the first layer 30, forming a frame around the first layer 30. By regulating the amount of the first layer 30 that is covered by the second layer 40, the moisture transmission rate of the first layer 30 can be controlled precisely. This allows for efficient control over the desiccant container's moisture uptake, and the desiccant container therefore can be modified easily for specific applications, such as domestic use, industrial use, container use and so forth.

The second layer 40 may be a coating applied to the first layer 30 during printing process, the only difference is that the coating is printed onto the reverse side of the first layer 30 (i.e. the side that will face into the container). The coating is applied by a "turner bar" in the printing process, and the coating is then synced with the actual printing. In order for the first layer 30 to be moisture permeable, the coating is printed onto the first layer 40 as a frame that runs along the edges of the first layer 40, as well as along what will be the top and bottom portion of each first layer once the roll of the material forming the first layer has been cut to size. The printing process could be a normal flexo or grafire process. Typical adhesive coatings are those that are compatible with the printing process and that are capable of being heat sealed to the third layer 40. The coating is also preferably waterproof, or at least water-resistant.

The third layer 50 is then laminated, joined or sealed to the second layer 40 to form a secondary seal 110. A clearly defined zone is formed where the primary and secondary seals do not overlap, called the container seal area 120 is formed. This allows for a very strong heat seal to be formed either with other container seal areas in the container 10, and/or with conventional polymeric materials such as polyethylene.

Referring to Figure 3, the first portion 20 is visible from an inner side of the container 10, with the first layer 30 being on the outer side and the third layer 50 being on the inner side. From viewpoint X, the second and third layers 40, 50 are cut away to show only the first layer 30; from viewpoint Y, only the third layer 50 is cut away to show the sealed first and second layers 30, 40; and from viewpoint Z, where no layers have been cut away, only the second and third layers 40, 50 are visible. The primary seal 100, secondary seal 110 and container seal area 120 are also shown. Referring to Figure 4, a sectional side view of a desiccant container 200 is shown with particular reference to the sealing areas of the first, second, third and fourth layers 230, 240, 250 and 260, respectively.

A primary seal 300 is formed between the first layer 230, which is made from paper, and the second layer 240, which is made from polyethylene. A secondary seal 310 is then formed between the second polyethylene layer 240 and the third layer 350, which is made from a micro-porous material such as Espoir™. A fourth layer 260 consisting of laminated polyethylene 262 and polyester 264 sheets is sealed to a zone of the second layer 240 referred to as the container seal area, to form a container seal 320. The container seal area is a zone of the primary seal 300 that does not overlap with the secondary seal 320. The container seal forms a pocket 280 for containing a desiccant material 270, in particular, calcium chloride.

It is important for the strength and stability of the desiccant container 200 that the secondary seal 310 be a separate seal from the container seal 320. In this way, the container seal 320, together with the primary seal 300, will absorb the bulk of stress which may be applied to the container 300, and will protect the secondary seal 310 from forces that impact on the container 200, for example, when the container is dropped, stepped on and the like. Thus, even though the secondary seal 310 may not be particularly strong, the relatively much stronger container seal 320 will provide the desiccant container 200 with sufficient strength and stability to withstand handling forces normally associated with these containers.

Referring to Figure 5, a sectional side view of another embodiment of a desiccant container 400 in accordance with the invention is shown. The desiccant container 400 includes a primary seal 500 formed from a first layer 430 that incorporates TYVEK™ and a second layer 440 that incorporates polyethylene. A secondary seal 510 is formed between the polyethylene of the second layer 440 and a third layer 450 of a micro-porous material such as Espoir™. A fourth layer 460 consisting of laminated polyethylene 462 and polyester 464 sheets is sealed to the second layer 440 in a container seal area only, to form a container seal 520. The container seal 520 defines a pocket 480 for containing a desiccant material 470, such as calcium chloride. Referring to Figure 6, a sectional side view of yet another embodiment of a desiccant container 600 is shown. The desiccant container 600 includes a primary seal 700 formed from a first layer 630 that incorporates paper and a second layer 640 that incorporates polyethylene. A secondary seal 710 is formed between the polyethylene of the second layer 640 and a third layer 650 of a micro-porous material such as Espoir™. A fourth layer 660 of polyethylene is sealed to the second layer 640 in a container seal area only, to form a container seal 720. The container seal 720 defines a pocket 680 for containing a desiccant material 670, such as calcium chloride.

Referring to Figure 7, a sectional side view of yet another embodiment of a desiccant container 800 is shown. The desiccant container 800 includes a primary seal 900 formed from a first layer 830 of paper and a second layer 840 of polyethylene. A secondary seal 910 is formed between the polyethylene of the second layer 840 and a third layer 850 of a micro-porous material such as Espoir™. A fourth layer 860 of clear polyethylene is sealed to a fifth layer 890 of paper, and the fourth layer 860 is then sealed to the second layer 840 in a container seal area only, to form a container seal 920. The container seal 920 defines a pocket 880 for containing a desiccant material 870, such as calcium chloride. The fifth layer 890 may have a cut-out area which forms a window 810, thereby permitting a user to view the contents of the container 800.

Layers 1 , 2 and 4 could also as an alternative be made from the same sheet of combined paper and polyethylene. The next figure explains this more clearly.

The desiccant material 870 may also include a visual indicating means, such as a colour indicator (not shown) that changes colour when a certain amount of vapour has been absorbed. The colour change could be used to indicate to a user that the desiccant container 800 should be replaced.

One or more of the layers of the desiccant container 800 and/or the desiccant material 870 may also include a fragrance, such as lavender, apple, citrus or the like, to freshen the air in the region of the container 800. Figure 8 shows two alternative methods of aligning the layers of the desiccant container, and will be described, by way of example only, using the same reference numerals as thosed used in Figures 1 and 2.

In Figure 8(A), the first portion 20 (comprising the first, second and third layers) is sealed to the second portion 60 by aligning the container seal area 120 on the first portion 20 with the forth layer 60 to form a framed container seal 1 000 along the edges of the container 10.

In Figure 8(B), the first portion 20 is folded in order to align the container seal area 120 with an inside portion of the folded material. Depending on the position of the container seal areas 120, the final container seals could either be on the edges of the container 1000 or at the top and bottom as well as the middle 1001 of the container 10. These, however, are only examples and are the only ways of sealing the desiccant containers.

Referring to Figure 9, a sectional side view of yet another embodiment of a desiccant container 1100 is shown.

The moisture permeable container 1100 includes primary 1200 and secondary 1210 seals on both sides of the container 1000. The layers 1130, 1140, 1150, 1160 and 1170 are aligned in order to seal only container seal areas of both portions, for also surrounding at least partially a desiccant material 1170. In this example, the desiccant material 1170 is calcium chloride.

In yet another, embodiment (shown in Figures 10 to 12), the difference between this embodiment and the first embodiment being the positioning of the third layer relative to the second portion.

Instead of the third layer only partially overlapping the second layer, in this embodiment the third layer covers the entire edge of at least one side of the second layer. As a result, the layer forming the second portion is adhered to the third layer to form the container seal, rather than mostly to the second layer (as occurs in the first embodiment). However, care must be taken during the formation of the container seal (i.e. the seal formed between the third layer of the first portion and the second portion) to ensure that it does not overlap completely with the secondary seal (i.e. the seal formed between the second layer and third layer). In this way, the portion of the secondary seal that does not overlap the container seal is located within the container that is formed by the container seal.

In another embodiment (not shown), it is also possible for the second layer to cover the first layer entirely, but to be only sealed to a portion of the first layer to form the primary seal substantially as described above. The portion of the second layer that is not sealed to the first layer should be breathable or made breathable, by perforations or punch marks, for example, so as to allow vapour to pass through the second layer.

The applicant believes that the invention described above is advantageous in that it provides a moisture permeable container having a high seal strength, and with high strength materials in the areas that require these, thereby to protect the container from leaking and/or bursting, while still allowing optimal water vapour absorption. It will be understood by a person skilled in the art that it is possible to alter the material used, while still remaining within the spirit and scope of the invention.

Claims

Claims:

1. A moisture permeable container including a first portion and a second portion adhered to each other so as to form a pocket, wherein the first portion includes: a first layer of a moisture permeable material; a second layer of material adhered to at least a peripheral zone of an inner surface of the first layer so as to form a primary seal; and a third layer of a moisture permeable material which is adhered to the first layer by the second layer so as to form a secondary seal; and wherein the second portion includes at least a fourth layer of material which is adhered to at least three edges of the first portion so as to form a container seal, the container seal being formed so that it excludes at least a portion of the secondary seal.

2. A container according to claim 1 , wherein the third layer only partially overlaps the second layer when forming the secondary seal, so that a portion of the second layer on each edge of the first portion remains exposed and is adhered to the fourth layer during formation of the container seal.

3. A container according to either of claims 1 or 2, which further includes a fifth layer of a removable, nonporous material removably adhered to an outer portion of the first layer.

4. A container according to any one of the preceding claims, wherein the fourth layer is not moisture permeable.

5. A container according to any one of the preceding claims, wherein the second portion of the container includes two or more layers.

6. A container according to any one of the previous claims, wherein the second portion includes three layers that are adhered to each other in the same way as the layers of the first portion, so as to form a container where both the first and second portions are capable of absorbing moisture.

7. A container according to claim 6, wherein the second portion is formed from substantially one half of the first portion which is folded into two portions.

8. A container according to any one of the preceding claims, wherein the moisture permeable material of the first layer is a breathable, monolithic, micro-porous, porous and/or fibrous material.

9. A container according to any one of the previous claims, wherein the first layer is manufactured from paper.

10. A container according to claim 9, wherein the first layer is a wet strength paper and/or a bond paper.

11. A container according to any one of claims 1 to 8, wherein the first layer is manufactured from a microporous material formed from polyethylene or polypropylene.

12. A container according to claim 11 , wherein the microporous material is formed from a polyethylene spun-bonded paper or a polypropylene-based film.

13. A container according to any one of the preceding claims, wherein the material of the first layer has a higher sealing temperature than the material of the second layer.

14. A container according to any one of the preceding claims, wherein the material forming the second layer is a porous, fibrous and/or non-moisture permeable material.

15. A container according to any one of the preceding claims, wherein the material forming the second layer is a high seal-strength material selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin, monolithic polymer and uncoated poly-olefinic polyethylene materials.

16. A container according to any one of the preceding claims, wherein the second layer is heat sealed to the first layer.

17. A container according to any one of claims 1 to 14, wherein the second layer is applied as a coating onto a peripheral edge of the first layer.

18. A container according to any one claims 1 to 16, wherein the second layer is formed from a sheet having a zone that is punched, cut out or otherwise rendered breathable prior to or at the time of sealing to the first layer, so that moisture is able to pass from the first layer through to the third layer.

19. A container according to any one of the preceding claims, wherein the breathable material of the third layer is a breathable, monolithic, micro-porous and/or porous material.

20. A container according to claim 19, wherein the third layer is a monolithic polyester material.

21. A container according to any one of the preceding claims, wherein the third layer does not permit the passage of water molecules in liquid form therethrough.

22. A container according to any one of the preceding claims, which includes a desiccant material located in the pocket formed between the third layer of the first portion and the second portion.

23. A container according to claim 22, wherein the desiccant material is selected from the group consisting of a hygroscopic desiccant substance, silica gel, bentonite clay, sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, attapulgite clay, magnesium sulfate, starch, clay and/or a super absorbent or mixtures thereof.

24. A container according to any one of the preceding claims, which further includes an absorption indicator for indicating the amount of water absorbed by the desiccant material.

25. A container according to claim 24, wherein the first or second portion includes a substantially transparent zone for viewing the absorption indicator.

26. A method of manufacturing a moisture permeable container, the method including the steps of: adhering a second layer of an adhesive material to a peripheral zone on at least three edges of a first layer of a moisture permeable material, thereby forming a first seal joining the first and second layers; adhering a third layer of a moisture-permeable material to the second layer thereby forming a second seal joining the first, second and third layers; and adhering a peripheral zone of a fourth layer to a peripheral zone of the portion formed from the first, second and third layers, thereby forming a container seal forming a container defining a pocket between the third and fourth layers..

27. A method according to claim 26, wherein the third layer only partially overlaps the second layer when forming the second seal, so that a portion of the second layer on each edge of the first portion remains exposed and is adhered to the fourth layer during formation of the container seal.

28. A method according to claim either of claims 26 or 27, wherein the first and second seals are formed consecutively or simultaneously.

29. A method according to any one of claims 26 to 28, wherein the container seal joins the fourth layer to the third layer.

30. A method according to any one of claims 26 to 28, wherein the container seal joins the fourth layer to the second layer.

31. A method according to any one of claims 26 to 30, wherein the first, second and third layers are folded in two and the fourth layer comprises one of the sides of the folded portion.

32. A method according to any one of claims 26 to 31 , wherein the container seal is stronger than the second seal.

33. A method according to any one of claims 26 to 32, wherein a desiccant material is inserted into the pocket formed between the third and fourth layers before the container seal is completely formed.

34. A method according to any one of claims 26 to 33, wherein the first, second and container seals are formed by heat sealing, bonding, laminating and/or gluing.

35. A container according to claim 1 , substantially as herein described with reference to any one of Figures 1 to 12 of the accompanying drawings.

36. A method of manufacturing a container according to claim 26, substantially as herein described.