AU2003229982A1 - Dehumidifying product - Google Patents

Description

WO 03/093733 PCT/GBO3/01924 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. Typically, these techniques suffer from various disadvantages as they typically require bulky and heavy WO 03/093733 PCT/GBO3/01924 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 03/093733 PCT/GBO3/01924 3 According to a first aspect the present invention provides a dehumidifying product comprising a support part of a sheet material, and a plurality of chambers carried by the support part on one side only, each chamber 5 containing a deliquescent agent and being bounded at least in part by a vapour-permeable liquid-impermeable membrane Preferably the chambers are elongate. Preferably such chambers are substantially parallel to one another. 10 Preferably the product has a stowed configuration with the support part outermost, around the chambers, and an operative configuration in which the support part is not around the chambers. 15 Preferably each chamber is removably mounted on the support part to permit individual replacement, for example once saturated. 20 The product has the advantage that the performance of the product may be adjusted by adding chambers to or removing chambers from the support. Alternatively the membrane may have damping means to adjust the air passage therethrough. The damping means may be a mechanical 25 damper, for example of the turning or sliding type. Generally, in the operative configuration the support part is generally planar. However this need not always be so. The product may, in use, be arranged to rest over a 30 shaped article, and to follow the shape thereof. Nevertheless the support part is then not around the chambers; the chambers are all fully exposed, on one side of the support part.

WO 03/093733 PCT/GBO3/01924 4 The support part may be of a flexible sheet material, so that it may be rolled up, into the stowed condition. In an alternative embodiment the support part may be 5 of a self-supporting sheet material, but having fold lines, so that it can be folded up, into the stowed configuration. In such embodiments, the product in the stowed configuration is preferably of triangular, rectangular (preferably square) or hexagonal cross 10 section. Fold lines may be thinned, as by scoring. This may be achieved from a moulding process or by a separate scoring step. Alternatively the sheet material may be sufficiently 15 flexible that the fold lines do not need to be thinned. Preferably the chambers are spaced apart by such an amount that in the stowed condition they pack together in a space-efficient manner. 20 Preferably when elongate chambers are employed they are prisms, preferably having 3-10 sides, most preferably 3-6 sides. 25 Preferably the product comprises 3-10 chambers, most preferably 3-6 chambers. When the product is of the type which can be folded up the number of chambers is preferably equal to the number of sides the product has, in the stowed configuration. 30 Each chamber preferably has a face in contact with the support part, and one or more faces projecting forwardly therefrom, said one or more faces preferably including an WO 03/093733 PCT/GB03/01924 5 opening which is covered by. the membrane (hereinafter called a membrane window). The cross-section of each chamber could, for example, be a semi-circle, a triangle or a rectangle (preferably a square). A preferred chamber 5 is a triangular prism. Preferably the upper forwardly projecting face thereof has a membrane window. The lower forwardly projecting face may if wished have a membrane window. The third face preferably does not since it typically abuts the support part. 10 Preferably the deliquescent agent is in contact with the membrane of a respective chamber. Preferably each chamber is full of or slightly overfilled by the deliquescent agent, such that the membrane is engaged with 15 or somewhat strained by it. Saturation of the deliquescent agent in a chamber may be determined by pressing on the membrane in order to assess the gel state of the deliquescent agent. 20 Alternatively, and preferably, the deliquescent agent may contain a colour-change agent acting as an indicator of the saturation of the deliquescent agent. In a given product the chambers need not all be 25 identical. They could be of different sizes (though preferably they are all of the same size); they could all contain the same deliquescent agent but in different amounts, or with different pre-saturation levels ex manufacture; they could have membrane windows of different 30 areas; they could employ different membranes, with different permeabilities. They could contain different deliquescent agents. It will be appreciated that if all of the chambers are identical they are likely to reach WO 03/093733 PCT/GBO3/01924 6 saturation at the same time. However if they differ they may reach saturation at different times. If only one chamber reaches saturation at one time it may be removed, for replacement, and whilst removed, the product is still 5 providing dehumidification, by virtue of the other chamber, or chambers. Preferably the deliquescent agent is able to absorb at least its own weight of water at 25 0 C. 10 Preferably, the deliquescent agent forms a liquid or gel on absorption of water vapour, and is such that liquid seeps from it. Preferred deliquescent agents include calcium chloride and/or magnesium chloride as these not 15 only exhibit an acceptable water absorption capacity but they are relatively non-caustic. Suitably, the deliquescent agent as defined above may be admixed with other agents selected from a binder, such 20 as starch, a perfume and an antimicrobial agent or combinations thereof. Preferably the support part is of a plastics material, preferably a thermoplastics material such as polyvinyl 25 chloride, polyethylene and polypropylene. Preferably the chambers comprise a plastics material, preferably a thermoplastics material such as polyvinyl chloride, polyester, polypropylene and polyethylene. 30 Preferably the chambers are formed by a moulding process, preferably from a sheet of plastics material (eg by vacuum forming) or from a polymer material in the melt (eg by injection moulding). Preferably an opening is formed in WO 03/093733 PCT/GBO3/01924 7 the moulding process or is subsequently formed; and is then closed by the membrane. Many suitable membranes are commercially available 5 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 membranes may be of polyethylene, polypropylene, polyester and polyamide. 10 The membrane may be secured to the chamber by an adhesive seal or heat seal. The dehumidifying product may have a formation 15 enabling it to be hung, preferably from one end of the product. The formation may, for example, be an aperture to receive a wall hook. Alternatively, and preferably, it is itself a hook formation. Preferably such a formation of any type is formed in or by the support part itself. 20 The chambers may be formed with lateral flanges, and the support part may be formed with tangs raised from the one side of the support part, such that the chambers may be slid into place on the support part by axial sliding 25 movement, so that the lateral flanges locate beneath the tangs. Preferably the dehumidifying product is such that it can stay in its stowed condition without the assistance of 30 separate parts, such as retaining bands or secondary packaging. This may be by virtue of its inherent properties or by virtue of a mechanical device, such as a press stud.

WO 03/093733 PCT/GB03/01924 8 The surface of the support part which faces outwards in the stowed configuration is preferably printed, for example with a trade mark, graphics, explanatory wording 5 and the like. Preferably there is no printed secondary packaging. However the dehumidifying product may suitably be wrapped in vapour- and liquid-impermeable packaging up to the point of sale, in order to have the maximum shelf life and/or utility for the customer. Such packaging can 10 be transparent film. Alternatively in lieu of such a film a peel-off cover strip can be provided over each membrane window, the cover strips being removed for use. In accordance with a second aspect of the present 15 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 a dehumidifying product of the first aspect from its stowed configuration to its operative configuration, and 20 b) locating it in the locus. The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: 25 Fig. 1 is a front view of a first embodiment of dehumidifying product of the present invention, in its in use configuration; 30 Fig. 2 is a perspective exploded view of the components of a desiccant chamber of Fig. 1; and WO 03/093733 PCT/GB03/01924 9 Fig. 3 is a perspective view of the product of Fig. 1, in its folded-up configuration; Fig. 4 is a perspective view of a second embodiment of dehumidifying product, in part-stowed configuration. 5 The dehumidifying product shown in Fig. 1 comprises a support part 2 of a self-supporting thermoplastics sheet material. The support part is generally rectangular and has four fold lines 4, all parallel to the lower, shorter 10 side 5 of the support part, and substantially horizontal in use. At the fold lines the sheet material is thinned, by a scoring step. By means of the fold lines the support part may be seen as divided into four identical rectangular zones 6 (apart from the bottom zone 61 having 15 two curved lower corners) and, at the top of the support part, an upper suspending zone 8 having the shape of an envelope flap, and with a hole 10 adjacent to its apex. In each of the four rectangular zones the support part 20 carries an elongate chamber 12, containing a deliquescent agent. The four zones and chambers are hereinafter called '"desiccant zones" and "desiccant chambers". Each desiccant chamber is an elongate equilateral triangular prism. Thus it has three identical rectangular faces. One face abuts 25 the support part and the other two faces project forwardly, terminating at an apex line 14. Around the entire periphery of each chamber there is a rim or flange 16. Each rectangular desiccant zone 6 is formed with tangs 18 raised from the plane of the support part, and as shown 30 in Fig. 1 the lateral edges of the flange 16 locate beneath these tangs in order to secure the desiccant chamber to the support part. For each chamber there are three tangs, namely a pair of lower tangs each located WO 03/093733 PCT/GBO3/01924 10 towards a respective corner of the chamber, and a single tang on the other side of the chamber, at a central position. The flanges 16 are in frictional engagement with the tangs so that the desiccant chamber is restrained from 5 sliding accidentally from its desiccant zone. To this end the flanges and tangs are dimensioned so that the tangs are somewhat resiliently displaced by the flanges. Each desiccant chamber is of generally self-supporting 10 moulded plastics construction. However the faces which project forwardly from the support part each have a membrane window. In this embodiment this is a large rectangular opening 19 (whether achieved by the moulding operation or subsequently) covered by a vapour-permeable 15 liquid-impermeable membrane 20 of TYVEK (Registered Trade Mark). For manufacturing convenience a single sheet of TYVEK is used, as is shown in Fig. 2. Sealing of the membrane can be by an adhesive or by application of heat. A deliquescent agent is then introduced into the chamber 20 so as to entirely fill the chamber, with the deliquescent agent in contact with the membrane 20, and the third wall closed off by means of an ordinary plastics film 22, vapour- and liquid-impermeable. The deliquescent agent remains in contact with the membrane 20. 25 The deliquescent agent is calcium chloride in granular form, in this embodiment. Once four chambers have been thus prepared they are 30 slid into place on the support part, to form the unfurled, operative configuration shown in Fig. 1. This structure may, for storage and transportation, be folded up into the furled or stowed square-section box form 24 shown in Fig.

WO 03/093733 PCT/GBO3/01924 11 3. It will be seen that the support part now extends around the chambers. The chambers pack or nest neatly together inside the "wrap" of the support part. The nesting is a function both of the triangular cross-section 5 of the chambers, and their parallel but spaced-apart relation, on the support part. The upper suspending zone 8 lays upon the lowermost desiccant zone 61 of the support part. If wished a small hook or fold-over tab may extend through hole 10, to effect securement in a simple manner. 10 Alternatively a simple attachment device such as a press stud, or VELCRO (Registered Trade Mark) pads may be used. In the Fig. 3 configuration the support provides ample free surface area for advertisement and information 15 purposes. All that is additionally desirable to provide a product at the point of sale is an inexpensive clear plastics film, impermeable to vapour, about the product. Thus, expensive and wasteful secondary packaging is minimised. 20 Fig. 4 shows a second embodiment which differs from the embodiment of Figs. 1 to 3 only in the following respects: 25 - there are only three elongate desiccant chambers 6 of triangular prism shape - the dehumidifying product in its stowed configuration is of triangular prism shape - each desiccant chamber has only one membrane 30 window 18. This membrane window, in use, is in the upper face, of the two forwardly-projecting faces of the chamber WO 03/093733 PCT/GBO3/01924 12 - the three desiccant chambers have membranes of different permeability, and do not reach saturation at the same time - in the upper suspending zone 8 of the support 5 part there is an integral hook 26 instead of a hole.

Claims (13)

1. A dehumidifying product comprising a support part of a sheet material, and a plurality of chambers carried by the 5 support part on one side only, each chamber containing a deliquescent agent and being bounded at least in part by a vapour-permeable liquid-impermeable membrane.

2. A dehumidifying product as claimed in claim 1 wherein 10 the chambers are elongate.

3. A dehumidifying product as claimed in claim 2 wherein the elongate chambers are substantially parallel to one another. 15

4. A dehumidifying product as claimed in any preceding claim wherein the product has a stowed configuration with the support part outermost, around the chambers, and an operative configuration in which the support part is not 20 around the chambers.

5. A dehumidifying product according to claim 4 wherein the support part is of a self-supporting sheet material having fold lines so that it can be folded up into the 25 stowed configuration.

6. A dehumidifying product according to any of claims 1 to 4 wherein the support part is of a flexible sheet material so that it can be rolled up into the stowed 30 configuration. WO 03/093733 PCT/GBO3/01924 14

7. A dehumidifying product as claimed in any preceding claim wherein the chambers are prisms having 3-10 sides. 5

8. A dehumidifying product as claimed in any preceding claim having 3-10 chambers.

9. A dehumidifying product as claimed in any preceding claim wherein the chambers are not all identical. 10

10. A dehumidifying product as claimed in any preceding claim wherein the chambers are removably mounted on the support part. 15

11. A method of absorbing water vapour from a locus, preferably an enclosed locus, comprising the step of locating a dehumidifying product as claimed in any preceding claim in the locus. 20

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

13. A method of absorbing water vapour substantially has described herein with reference to the drawings and 25 description.