AU2003224317A1 - Dehumidifying product - Google Patents

Description

WO 03/092863 PCT/GB03/01841 1 DEHUMIDIFYING PRODUCT The present invention relates to a product and method for absorbing water vapour, particularly, although not 5 exclusively, for dehumidifying air in a confined space. Humidity, or water vapour in air, is often undesirable as water vapour may interfere with the storage of moisture sensitive materials, such as foodstuffs, cosmetics, 10 pharmaceuticals, household goods and clothes, or it may adversely effect the operation of moisture sensitive equipment. This problem may be particularly pronounced in those areas where humidity levels are particularly high, such as those countries having hot humid climates. 15 It is therefore often desirable to dehumidify air. Traditional methods for dehumidifying air include the use of mechanical refrigeration equipment and water absorbent materials, such as silica gel. 20 Typically, methods employing refrigeration equipment involve cooling air to a predetermined temperature below its dew point, so that water condenses from the air and the water may be drained away. Thereafter, the air may be 25 reheated to a predetermined warmer temperature. Techniques including absorbent materials may include continuous operation systems so that water is absorbed by the absorbent in a first cycle and then water desorbed from the absorbent by the application of heat in a second 30 cycle. Suitably, these techniques suffer from various disadvantages as they typically require bulky and heavy WO 03/092863 PCT/GB03/01841 2 equipment, such as compressors, fans and heaters, which are interconnected by a network of pipes so that water vapour is absorbed continuously from air. Typically, such systems are ill-suited for operation in a confined or 5 limited space. Moreover, the cost associated with such systems may prohibit their use in a domestic environment. In an attempt to overcome the disadvantages associated with using the aforementioned systems in a confined or 10 limited space, alternative techniques have been developed that include exposing air to an absorbent material. In particular, portable smaller devices comprising a sealed vapour permeable container housing an absorbent material have been employed for dehumidifying air in a limited or 15 confined space, particularly in a domestic environment. Although absorbents such as silica gel may be employed in these devices, typically silica gel only absorbs up to 30% its weight of water and it is necessary to employ an 20 absorbent having a higher capacity for water vapour absorption to prolong the life and improve the efficiency of the device. Suitably, hygroscopic deliquescent agents, such as calcium chloride, which may absorb 4 to 5 times its weight of water, have been employed in such devices. 25 On absorption of water vapour, the deliquescent agent dissolves to form a liquid. Although these devices have gone some way to solving the problems associated with absorbing water vapour in a 30 confined or limited space, particularly in a domestic environment, such devices have been bulky and with poor design aesthetics.

WO 03/092863 PCT/GBO3/01841 3 According to a first aspect the present invention provides a dehumidifying product comprising two joined cavities with a fold line between them, one cavity containing a deliquescent agent and the other cavity being 5 for the collection of liquid, the cavity for the deliquescent agent being closed by a vapour-permeable membrane, wherein the product may be folded about the fold line to reconfigure it from an operative configuration in which water vapour can be absorbed by the deliquescent 10 agent and in which liquid can pass from the cavity for the deliquescent agent to the liquid collection cavity, to a stowed configuration in which the cavities are in face to face relation. 15 Preferably the membrane of the cavity for the deliquescent agent is liquid-impermeable, to ensure that liquid can pass only into the liquid collection cavity. Preferably the product is substantially unable to 20 absorb water vapour when in the stowed configuration. This may be because of an external agency, for example a plastics wrapping, but is preferably because of the product itself, for example because of the occlusion of the membrane by the liquid collection cavity, in the 25 stowed configuration. In preferred embodiments the liquid collection cavity is sealed with a vapour-impermeable liquid-impermeable membrane such as to act as a barrier to vapour and liquid. 30 Thus it may be, for example, a metal foil or a vapour- and liquid-impermeable plastics film. However the vapour permeable membrane which closes the cavity for deliquescent agent is preferably liquid-impermeable and WO 03/092863 PCT/GB03/01841 4 the same material may be used to close the liquid collection cavity as well. It will be appreciated that although a vapour-permeable liquid-impermeable membrane may be relatively expensive manufacturing costs may be 5 reduced by using a single membrane to cover both cavities. Preferably the product has an operative configuration in which the membrane of the cavity for deliquescent agent and the part of the liquid collection cavity in face to 10 face relation with said membrane in the stowed configuration (for example the membrane of the liquid collection cavity when such a membrane is provided) are side by side and generally co-planar. Preferably this operative configuration is a (or the) rest configuration 15 of the product. The stowed configuration may also be a rest configuration (eg if the product is bistable). However it need not be; means may be provided to keep it in that configuration, thereby restraining it against opening. 20 Preferably the cavities are in face to face contact when in the stowed configuration. Preferably the deliquescent agent is in contact with 25 the membrane of the respective cavity, at least in the operative configuration. Preferably that cavity is full of or slightly overfilled by the deliquescent agent, such that the membrane is somewhat strained by it. 30 Preferably the membrane, or membranes, are secured in place by adhesive or heat sealing. Heat sealing is preferred. The product is preferably formed with a rim or flange around its periphery to provide a flat band against WO 03/092863 PCT/GB03/01841 5 which the membrane(s) may engage. A portion of the rim or flange furthest from the fold line may be formed with a formation enabling the dehumidifying product to be hung, preferably from one end of the product, with the liquid 5 collection cavity below the cavity for the deliquescent agent. The formation may, for example, be an aperture to receive a wall hook. Alternatively, and preferably, it may itself be a hook formation. 10 The fold line is preferably formed by the material which forms the cavities. That is, there preferably is no discrete further part. Preferably the fold line is constituted by a rib between the cavities, the rib preferably being formed by adjacent walls of the 15 respective cavities, with a web of material connecting them. The material may be sufficiently thin and/or flexible as to form a fold line without any further measure, or, preferably, it is thinner than the material elsewhere. It may, if wished, be moulded with a thinned 20 fold line in the form of a "score" (whether arising from a moulding process or by a discrete scoring process). Suitably there are one or more passageways, which may be covered by a liquid-permeable membrane but which are 25 preferably open, to permit liquid to pass from the cavity for the deliquescent agent to the liquid collection cavity. A convenient way of providing one or more passageways 30 between the cavities is to provide heat sealing of the membrane(s) to the region between them (for example to the web mentioned above) but to leave the sealing incomplete. Thus there will be a region, or regions, left unsealed.

WO 03/092863 PCT/GB03/01841 6 The arrangement is such that liquid can run from the cavity for deliquescent agent, but the deliquescent agent is retained in that cavity. Incomplete sealing can be achieved by selective absence of adhesive or by selective 5 avoidance of heat sealing or by moulding a recess or recesses where required. Preferably the deliquescent agent absorbs at least its own weight of water, at 25 0C. 10 Preferably, the deliquescent agent forms a liquid or gel on absorption of water vapour. Preferred deliquescent agents include calcium chloride and/or magnesium chloride as these not only exhibit an acceptable water absorption 15 capacity but they are relatively non-caustic. Suitably, the desiccant as defined above may include other active agents selected from a binder, such as starch, a perfume and an antimicrobial agent or 20 combinations thereof. Preferably the cavities are of a plastics material, preferably a thermoplastics material such as polyvinyl chloride, polyethylene and polypropylene. Preferably they 25 are formed by a moulding press, preferably from a sheet of plastics material (eg by vacuum forming) or from a polymer material in the melt (eg by injection moulding). Many suitable vapour-permeable liquid-impermeable 30 membranes are commercially available and/or described in literature. Preferably a material is selected that can admit at least 500g, more preferably at least l,000g, most preferably at least 2,000g water vapour/m 2 /day. Suitable WO 03/092863 PCT/GB03/01841 7 membranes may be of polyethylene, polypropylene, polyester and polyamide. The polyethylene material sold under the trade mark TYVEK is one example. 5 Preferably the dehumidifying product is such that it can stay in its stowed condition without the assistance of separate parts, such as retaining bands or complex secondary packaging. This may be by virtue of its inherent properties or by virtue of a mechanical device, such as a 10 co-moulded hook and eye. A surface of the product, external in the stowed configuration, is preferably printed upon, for example with a Trade Mark, graphics, explanatory wording and the 15 like. Preferably the surface comprises two major surface portions, formed by flat bottom walls of the cavities. Preferably they are parallel to one another in the stowed 20 configuration. Preferably both are printed upon. Preferably there is no printed secondary packaging. However the dehumidifying product may suitably be wrapped in vapour- and liquid-impermeable packaging up to the 25 point of sale, in order to have the maximum shelf-life and/or utility for the customer. Such packaging can be transparent plastics film. In accordance with a second aspect of the present 30 invention there is provided a method of absorbing water vapour from a locus, preferably an enclosed locus, comprising the steps (in either order) of a) reconfiguring WO 03/092863 PCT/GB03/01841 8 a dehumidifying product of the first aspect into its operative configuration, and b) locating it in the locus. The invention will now be further, by way of example, 5 with reference to the accompanying drawings, in which: Fig. 1 is a front view of a first embodiment of dehumidifying product of the present invention, in its in use configuration; 10 Fig. 2 is a side sectional view of the product of Fig. 1; Fig. 3 is a front view of the product of Fig. 1, in its stowed configuration; 15 Fig. 4 is a side view of the product of Fig. 1, in its stowed configuration. Fig. 5 is a perspective view of a second embodiment, in 20 its stowed configuration; Fig. 6 is a side view of the product of Fig. 5, partly open; and 25 Fig. 7 is a perspective view of the product of Fig. 5, in its in-use configuration. The dehumidifying product shown in Fig. 1 comprises a tray 2 of a self-supporting thermoplastics sheet material. 30 As best shown in Fig. 1, the tray is oval in frontal appearance. It has two identical cavities 4, 6. They are separated by a fold line 8. Fold line 8 is in the form of WO 03/092863 PCT/GB03/01841 9 a rib, the rib being formed by adjacent side walls 10, 12 of the two cavities, connected by a web 14. As a consequence of the product being of generally 5 oval appearance in frontal view, and having a fold line between its two cavities, each cavity is of semi-oval shape, in front view. The tray 2 has a rim 16 extending all around its 10 periphery. At its upper end the rim is wider and is formed with a hook 18, for hanging. Each cavity is formed with a flat bottom wall 19. 15 A single membrane 20 is secured in place over the tray, so as to close the cavities. The membrane is a vapour-permeable liquid-impermeable membrane sold under the name TYVEK (Registered Trade Mark). Sealing is effected around the whole of the rim 16, but in the fold 20 line, the sealing onto the web 14 is only intermittent. The upper cavity 4 is entirely filled with calcium chloride, as deliquescent agent, such that substantially the entire surface of the membrane over the upper cavity 25 is in contact with calcium chloride. After manufacture the product may be folded about the fold line 8, into the compact stowed condition shown in Figs. 3 and 4. In this condition the product resembles the 30 shell of a bivalve. Any propensity to open before it is needed could be restrained by a mechanical means on the device, or even by a spot of releasable adhesive between the contacting parts. Preferably, however, this is not WO 03/092863 PCT/GB03/01841 10 done. Preferably the product is retained in its stowed condition by means of packaging. In relation to packaging, it will be appreciated that 5 the flat bottom walls of the cavities provide an area for advertisement and information purposes. Accordingly they may be printed on. All that is additionally desirable is an inexpensive clear plastics film, impermeable to vapour, about the product, to keep it in good condition before 10 sale. Thus, expensive and wasteful printed secondary packaging is not required. When the product is purchased and opened from its stowed condition it adopts the operative condition shown 15 in Figs. 1 and 2, and is hung in place, with the membrane in a generally vertical plane, with the liquid collection cavity lowermost. Water vapour passes through the membrane 20 and is absorbed by the deliquescent agent in the upper cavity 4. After substantial absorption of water 20 vapour, liquid is given up by the deliquescent agent and can run through the passageways left between the web 14 and membrane 20, by virtue of the intermittent sealing therebetween. Thus, liquid collects in the lower cavity 6. However, because of its particulate characteristics and 25 the small size of the passageways the deliquescent agent cannot fall into the lower cavity 6, even at the commencement of use when it is dry. In Figs. 5-7 showing the second embodiment the 30 reference numerals correspond to those used in Figs. 1-4. The embodiments are similar, but that of Figs. 5-7 has the following substantial differences: WO 03/092863 PCT/GB03/01841 11 - the fold line 8 is not formed by the side walls of the cavities. Rather, each cavity has a flange, and the flanges meet at a hinge. - the cavities are asymmetric. The liquid collection 5 cavity 6 is considerably deep than the cavity 4 for the deliquescent agent. - the cavity 4 for the deliquescent agent is covered by a vapour-permeable liquid-impermeable membrane 20 whereas the liquid collection cavity is covered by a 10 vapour- and liquid-impermeable membrane 20.

Claims (9)

1. A dehumidifying product comprising two joined cavities with a fold line between them, one cavity containing a 5 deliquescent agent and the other cavity being for the collection of liquid, the cavity for the deliquescent agent being closed by a vapour-permeable membrane, wherein the product may be folded about the fold line to reconfigure it from an operative configuration in which 10 water vapour can be absorbed by the deliquescent agent and in which liquid can pass from the cavity for the deliquescent agent to the liquid collection cavity, to a stowed configuration in which the cavities are face to face relation. 15

2. A dehumidifying product according to claim 1 wherein the liquid collection cavity is closed by a liquid impermeable membrane. 20

3. A dehumidifying product according to claim 2 wherein a single sheet of a vapour-permeable liquid-impermeable membrane closes both cavities.

4. A dehumidifying product according to claim 2 or 3 25 wherein in an operative configuration of the dehumidifying product the membrane of the cavity for the deliquescent agent and the membrane of the liquid collection cavity are generally co-planar. 30

5. A dehumidifying product as claimed in any preceding claim wherein the bottom wall of each cavity is flat and the outwardly facing side (in the stowed condition) of at least one said bottom wall is printed upon. WO 03/092863 PCT/GB03/01841 13

6. A dehumidifying product as claimed in any preceding claim wherein there is a web between the cavities and a said membrane is secured to the web but so as to leave at 5 least one passage between the membrane and the web, for liquid to run through, from the cavity for the deliquescent agent to the liquid collection cavity.

7. A method of absorbing water vapour from a locus, 10 preferably an enclosed locus, comprising the steps (in either order) of a) reconfiguring a dehumidifying product as claimed in any preceding claim from its stowed configuration to its operative configuration, and b) locating it in the locus. 15

8. A dehumidifying product substantially as described herein with reference to the accompanying drawings.

9. A method of absorbing water vapour substantially has 20 described herein with reference to the drawings and description.