WO2004014524A2

WO2004014524A2 - Device for the controlled adsorption of humidity

Info

Publication number: WO2004014524A2
Application number: PCT/FR2003/002442
Authority: WO
Inventors: Jean-Francois Lafougere; Pierre Mairey
Original assignee: Amcor Flexibles Sps
Priority date: 2002-08-02
Filing date: 2003-08-01
Publication date: 2004-02-19
Also published as: FR2843042A1; WO2004014524A3; FR2843042B1; AU2003269084A1

Abstract

The invention provides a device (1) for absorbing humidity which comprises a bag (4) defined by a wall containing an absorbent (7). Said device (1) is characterised in that said wall has at least two regions, whereby a first region (2) is impermeable to steam and to liquids and a second region (3) is permeable to steam and impermeable to liquids.

Description

DEVICE FOR THE CONTROLLED ADSORPTION OF MOISTURE

The present invention relates to a device for the controlled adsorption of moisture. In the present application, by humidity is meant the water vapor contained in the air.

The presence of humidity in the ambient air is often undesirable. This is particularly the case in certain regions' where climatic conditions induce high humidity levels in the air.

When these percentages are high, humidity can be detrimental to the integrity of the dwelling or objects therein by * inducing a number of phenomena, such as paint blistering or cracking, peeling or yellowing of the wallpaper, of. mold, halos, saltpetre formation, rust, swelling and crackling woodwork. In the case of electronic equipment, it can be vital for the proper functioning of the devices, whether they are conditioned or stored in a low humidity atmosphere during transport.

The . Moisture problems are also particularly monitored in the food sector since they are likely to cause the deterioration of the physical and organoleptic qualities of food. A humid environment can encourage the development of molds or bacteria that affect the appearance, consistency and taste of food products. These changes can even result in expiration of food products, which represents a significant risk of loss of product or worse, intoxication of the consumer.

Attempts have been made to solve these humidity problems by proposing devices adsorbing moisture to be placed in environments for packaging food products or electronic devices. Such devices consist of a compartment made of material permeable to humid air, containing an adsorbent. A device of this type is described in particular ^' in ^' patent application FR 2 773 787. If indeed such a device is effective in eliminating the problems associated with the presence of moisture in the storage environment. However, the adsorption of moisture is such that it leads to the drying of the products. These devices do not allow control of the adsorption of moisture.

However, especially in the food sector, controlling the humidity of the storage environment is crucial. Indeed, to keep all their physical and organoleptic qualities in food products, it is essential that they are conditioned in an environment that is neither too humid nor too dry. The consequences of an excessively humid environment have already been mentioned above. An excessively dry packaging environment inevitably induces the desiccation of food, thus seriously altering their physical properties ≤. For example, desiccation leads to rubbery, dry or even brittle foods. It goes without saying that such alterations are undesirable for the consumer. Other devices currently on the market are complicated and very sophisticated mechanical devices that allow humidity control. This is particularly the case in museums where the exhibits must be kept in a humidity-controlled atmosphere. However, these devices require a heavy investment and a significant maintenance.

There is therefore a need for a simple device. inexpensive to manufacture and control humidity in packaging environments for products, especially food, allowing all their qualities to be preserved.

The Applicants have the merit of having successfully developed such a device.

The device (1) for the controlled adsorption of moisture according to the invention comprises a pocket (4) defined by a wall containing an adsorbent (7), said device (1) being characterized in that said wall comprises at least two regions,

- a first region ^" (2) impermeable to water vapor and to liquids;

- a. second region (3) permeable to water vapor and impermeable to liquids. In the sense _. of the present invention, the term “adsorbent” means a moisture adsorbent, that is to say any substance capable of retaining molecules of water in the liquid or gaseous state on its surface due to the intervention of superficial forces. Moisture adsorption being defined as the action of retaining water molecules at the gaseous state, which is found in moist air, on the surface of the moisture adsorbent due to the intervention of surface forces. Adsorption is reversible by the phenomenon of desorption. Controlled adsorption is defined in the present application as the control of the quantity by mass of water vapor which is adsorbed in a given time. The control of adsorption therefore allows the regulation of humidity at a given rate, predetermined according to the conditions required for the storage environment.

In the device (1) according to the invention, the first and second regions (2), (3) define the wall of the closed pocket (4). The first and second regions

(2), (3) are both made from a material impermeable to liquids. The pocket (4) is therefore a closed volume impermeable to liquids.

The second region (3) is however permeable to water vapor contained in humid air. Given that only the second region (3) is permeable to water vapor over the entire wall of the bag (4), the adsorbent (7) can only adsorb water vapor through this second region (3).

In practice, in the device (1) according to the invention, the surface occupied by the second region (3) defines the exchange surface for the adsorption of the water vapor contained in the humid air. It is indeed the only surface of the device which is permeable to water vapor contained in humid air. Thus, the larger the area of the second region (3) relative to the total area of the pocket (4), the greater the exchange area the higher the adsorption of water vapor, the higher the adsorption. It is therefore possible to control the adsorption of water vapor by playing on the surface of the second region (3). Depending on the humidity of the environment to be treated, the adsorption will therefore be adjusted by playing on the surface occupied by the second region (3) relative to the total surface of the pocket (4). In other words, in the device according to the invention, the surface of the second region (3) is therefore chosen so as to allow control of the adsorption of moisture. The humidity can thus be regulated at a determined rate in the storage environment for the products.

The first and second regions (2) and (3) form the wall of the pocket (4). They are juxtaposed on at least part of the pocket, so that at least part ^' of the second region (3), which is the only region permeable to water vapor, can allow the vapor d water to access the adsorbent (7). However, the first and second regions (2) and (3) can be

. superimposed on part of their surface, in particular at their assembly points. Preferably, the surface of the second region (3) represents 1 to 99% of the wall of the pocket (4) and more preferably, less than 50% of the surface of the wall of the pocket (4).

By way of nonlimiting example, the first region (2) can represent more than 50% of the wall of the pocket (4) and the second region (3) has the shape of a disc and represents less than 50% of the wall of the pocket. The disc of the second region (3) is actually a window adsorption. This adsorption window, as its name suggests, will be the window through which the adsorption will take place. In other words, the window is a communication channel between the adsorbent and the water vapor contained in the humid air. So that the device (1) is closed and impermeable to liquids, this adsorption window is closed in a sealed manner by the second region (3) which is made of material permeable to water vapor. Water vapor will therefore be able to be adsorbed by the adsorbent (7) through the second region (3) which covers the adsorption window. Once adsorbed, the water is condensed and remains trapped inside the liquid-impermeable volume defined by * the wall of the pocket (4). The adsorption window can have any shape. In particular, it can be triangular rectangular, square or even circular-

As regards more "precisely the first region (2) of the device, this is made from a material impermeable to humid air and to liquids.

It can have any shape or size. This material can also be rigid or flexible. This

'first region (2) forms, with the second region (3), the wall of the pocket (4) closed. As indicated above, their assembly is sealed, that is to say that the first region and second regions (2), (3) define a volume impermeable to liquids when they are assembled to form the wall of the pocket ( 4). Preferably, the first region (2) will be produced from a film of laminated, extruded or coextruded material, preferably a polyethylene film. These materials can advantageously be flexible.

As for the second region (3), it can also have any shape and is made from a material permeable to water vapor and impermeable to liquids.

This material can also be rigid or flexible. The second region (3) can in particular have the shape of a rectangle of a square or of a disc. . Preferably, the material of the second region (3) is chosen from nonwoven and / or tear-resistant materials. The term “tear-resistant material” means a material which is not tearable by hand. More preferably, these materials are based. of polyethylene or polyethylene filaments. high density such as, in particular of the TYVEK® type (DUPONT DE NEMOURS). The preferred TYVEK® is TYVEK® type 1073B.

The first and second regions (2), (3) can be assembled by any means ensuring the impermeability of the device (1) to liquids vis-à-vis the external environment. Assembly methods include bonding, thermal welding or even ultrasonic welding.

As described above, the bag (4) defined by the first and second regions (2), (3) contains at least one adsorbent (7). The appropriate adsorbents, that is to say capable of adsorbing the water vapor contained in the air, can be chosen from the group comprising zeolites, natural or synthetic, sieves molecular, silica, micro or macroporous gels, clays and their mixtures.

A particularly advantageous embodiment of the device (1) according to the invention is that in which the adsorbent (7) is silica gel, the first region (2) is produced from polyethylene and the second region (3 ) is made from TYVEK® material. '

It can also be interesting to place * a

10 absorbent inside the pocket (4). This absorbent will have the function of absorbing liquids resulting from the adsorption of moisture by the adsorbent (7) in the pocket (4).

Advantageously, the pocket (4) can also

15 contain a gelling agent. This gelling agent will have the function of gelling liquids from the absorption and / or adsorption of liquids in the bag (4).

In certain applications, it may also be advantageous to provide at least one support for the

20 diffusion of active substances. These substances can be in particular bactericides, deodorants, anti-rust agents, colored indicators, either to indicate the humidity of the air, or to visualize the degree of saturation of the adsorbent (7) .

25 .. In a particular embodiment, .these are the materials of the first region (2) and / or of the second region (3) which will serve as a support for these active substances. In this case, these materials allow the supported active substances to diffuse in

30 the humid environment. Active substances can be applied to the support material by any technique known to those skilled in the art, in particular by spraying, coating, soaking, padding or bonding. It is also possible to provide a support independent of the pocket (4) for these active substances. This independent support can be fixed outside or inside the device by any means known to those skilled in the art, in particular by gluing, welding or stapling.

In another particular embodiment, it is the adsorbent (7) which can serve as a support for the active substances. It is also possible * to mix the adsorbent (7) with a support material for the active substances.

In order to retain all of its adsorbent qualities. to the device (1) before its use, it is advantageous to protect the second region (3) from humid air thanks to a protective and peelable film (6). By peelable is meant a film reversibly attached to the second region

(3), for example by means of an adhesive film. In other words, this film (6) is ^'easily removable and without causing damage to ^i' a pocket (4). The material of this peelable protective film (6) is of course impermeable to water vapor. Suitable peelable materials are for example films made of laminated, extruded or coextruded materials, in particular of polyethylene, polyamide / polyethylene, polyester / polyamide or else a laminate of paper / polyethylene.

The protective and peelable film (6) is removed to put the device (1) into service. Once the film (6) is removed, the second region (3) is in contact with the air wet. The water vapor contained in this humid air will be adsorbed by the adsorbent (7) passing through the material permeable to water vapor of the second region (3). 5 The device (1) according to the invention is single-use, it is discarded once the adsorbent (7) is used, that is to say when it no longer fulfills its adsorption function of the water vapour. The user therefore does not need to open the device (1) to ^• recharge it with adsorbent (7). This has

10 has the advantage of avoiding the risk of spilling the adsorbent (7) in the environment to be protected. The device (1) according to the invention therefore remains completely sealed vis-à-vis the humid environment to be treated and this throughout its lifetime.

15. The invention will now "be described in more detail using the figures without limiting the invention to the embodiments shown alone.

Figure 1 is a front view of an embodiment of the device (1) according to the invention.

Figure 2 is an exploded view of an embodiment of the device (1) according to the invention.

Figure 3 is a three-quarter view and partially broken away of this embodiment of the device (1) according to the invention.

25 .- In Figure 1, the device (1) according to the invention has a rectangular shape and comprises a first region

(2) and a second region (3). The first region (2) has a rectangular shape and is impermeable to water vapor and liquids. The second region (3) has the form

30 of a disc and is permeable to water vapor and impermeable to liquids. The strip (3S) on the circumference of the disc of the second region (3) represents the joining points of the first and second regions. (2), (3). In other words, the first and second regions (2), (3) are welded to this strip. The strip (4) represents the assembly strip according to which the device according to the invention is closed.

In Figure 2, the device (1) according to the invention is shown in an exploded view. The first region (2) has the form of two sheets (2A) and (2B) comprising the adsorption windows (2FA) and (2FB). The second region (3) has the form of two discs (3A) and (3B). During assembly, the discs (3A) and (3B) of the second region (3) are welded on their circumference to the sheets (2A) and (2B) of the first region so as to close the adsorption windows ^' (2FA) and (2FB). The adsorbent (7) is located inside the pocket (4), once the latter is assembled. The peelable films (6A) and (6B) protect the second regions (3A) and (3B) from humid air.

In Figure (3), the device (1) according to the invention is partially shown. torn off once assembled and in operation, that is to say once the peelable films (6A) and (6B) have been removed. The sheets of the first region (2A) and (2B) were welded together according to the weld strip (4). The discs of the second region (3A) and. (3B) were welded to the strip (3S) of their circumference. _. The adsorbent (7) is located inside the pocket (4) defined by the assembly of the sheets of the first region (2A), (2B) and the discs from the second region (3A), (3B). Once assembled, these two regions define a closed pocket (4) impermeable to liquids.

The example which follows is intended to illustrate a particular embodiment of the device according to the invention without limiting the invention to this single embodiment.

EXAMPLE OF A DEVICE ACCORDING TO THE INVENTION An adsorbent device for the adsorption of moisture in accordance with the invention is produced, of total size 15 x 11 cm with the following materials: two identical polyethylene sheets of dimension 15 x 11 cm for the first region (2), two identical TYVEK® discs with a radius of 6 cm for the second region (3), and

The discs are welded to the sheets on a strip of 1 cm around the circumference of the disc in order to close the adsorption windows. The sheets having the adsorption windows thus closed are then welded together on three on their side to allow the filling of the bag (4) with adsorbent (7) (100 g of silica gel). Once filled with adsorbent (7), the bag (4) is closed on its last side in order to obtain a bag (4) impermeable to liquids.

Claims

1. Device for the adsorption of moisture (1) comprising a pocket (4) defined by a wall containing an adsorbent (7), said device being characterized in that said wall comprises at least two regions,

- a first region (2) impermeable to water vapor and to liquids,

- a second region (3) permeable to water vapor and impermeable to liquids.

2. Device according to claim 1, in which the second region (3) is produced from a material chosen from. Nonwoven and / or tear-resistant materials, preferably based on high density polyethylene, and more preferably based on TYVEK®.

3. Device according to either of claims 1 or 2, in which the first region (2) is produced from a material chosen from films made of extruded or coextruded laminated materials, preferably from polyethylene .

4. Device according to any one of claims 1 to 3 wherein the adsorbent (7) is chosen from the group comprising les-zeolites, natural or synthetic, molecular sieves, silica gels, micro or macroporous, clays and their mixtures.

5. Device according to ^• any one of claims 1 to 4 wherein the second region (3) is protected from moist air by a peelable film (6).

6. Device according to any one of claims 1 to 5, wherein the pocket (4) further contains an absorbent.

7. Device according to any one of claims 5 to 6, in which the bag (4) also contains a gelling agent.

8. Device according to any one of claims 1 to 7 further comprising a support for active substances.

9. Device according to claim 8, in which the active substances are chosen from the group comprising bactericides, deodorants, anti-rust agents, colored indicators, either to indicate the humidity of the air, or again for

15 visualize the degree of saturation of the adsorbent.

10. Device according to any one of claims 1 to 9 in which the first region (2) represents more than 50% of the wall of the pocket (4) and in which the second region (3) has the shape of a disk

-20 and represents less than 50% of the wall of the pocket.

11. Device according to any one of claims 1 to 10 in which:

- * the adsorbent (7) is silica gel; <'- the first region (2) is produced from polyethylene; the second region (3) is made from material of the TYVEK® type.

12. Device according to any one of claims 1 to 11 wherein the surface of the second region (3) are chosen so as to allow control of the adsorption of moisture.