GB2563375A

GB2563375A - A thermal pack

Info

Publication number: GB2563375A
Application number: GB1705801.7A
Authority: GB
Inventors: Neville Fellows Adrian
Original assignee: Hotties Thermal Packs Ltd
Current assignee: Hotties Thermal Packs Ltd
Priority date: 2017-04-11
Filing date: 2017-04-11
Publication date: 2018-12-19
Anticipated expiration: 2037-04-11
Also published as: GB2563375B; GB201705801D0

Abstract

A thermal pack 1, primarily for therapeutic use, has a flexible, impervious outer container or pouch 2 that is sealed to retain a liquid 5 inside. The pack is capable of maintaining its sealed integrity when heated to at least 80°C in a microwave oven. A non-rigid, absorbent filling 4 is located within the pouch and is capable of absorbing at least eight times its own weight of the liquid. The pouch is a laminate of a stretch-resistant fabric (e.g. woven from nylon 6,6 fibres) and an impervious elastomeric polymer such as polyethylene. The compliant absorbent filling includes superabsorbent fibres 6 (such as sodium polyacrylate) adhered to a backing sheet 7. The liquid may be water, present in a quantity that is at least eight times the weight of the superabsorbent fibres, and containing an antimicrobial preservative. The absorbent filling may include woven or nonwoven textile material 8 such as cellulosic fbres. The pouch is preferably vacuum sealed.

Description

A THERMAL PACK

The present invention relates to a thermal pack and in particular but not exclusively to a thermal pack for therapeutic use. The pack could, however, be used for the application of heat in any suitable situation to both live and inanimate subjects. The pack is capable of use as a heat pack and also as a negative heat pack, i.e. a cool pack, to abstract heat from live and inanimate subjects to which it is applied.

A conventional thermal pack used for therapeutic use is a hot water bottle. Whilst modern hot water bottles, which are made of rubber, are flexible they have the major disadvantage that they must be filled with hot water, which is usually at a temperature at or nearing boiling point. This is dangerous, particularly for children, the elderly, and persons with impaired movement or vision. To overcome this disadvantage gel packs and wheat bags have been developed that can be heated in a microwave oven. However, these packs tend to be expensive and are also hazardous as the overheating of gel packs can cause bursting, thereby spilling hot, sticky gel, and the overheating of wheat bags can pose a fire hazard.

In WO97/41814 is described a heat pack capable of being heated to at least 55°C that comprises a flexible impervious outer container in which is located a porous, non-rigid filling material that has absorbed at least its own weight of a liquid, primarily water, air having been removed from the outer container prior to it being sealed. This pack is capable of being heated in a microwave oven and overcomes the aforementioned disadvantages because it does not pose a fire hazard and does not leak hot gel if it bursts. The porous filling material in this pack may comprise a nonwoven textile material, a sponges or other textile fill. Super absorbent polymers could also be added to give a gelling effect to the water. In this way it was possible to obtain ratios of 1 part fill to 5 parts of water to produce a commercially useful product. Somewhat higher ratios of water to fill were attainable, but these tended to have drawbacks of weight or bulk which detracted from their practical application, making the pack less flexible. The maximum temperature to which the pack can be heated is also less than desired in some therapeutic applications.

It is an object of the present invention to provide an improved thermal pack over that described above by provided a pack having a greater thermal capacity and significantly more flexibility. Greater flexibility would enable the thermal pack to be made in shapes that can conform to areas of the body, for example the neck or a limb, thereby increasing the range of therapeutic applications for which the pack is suitable.

According to the present invention there is provided a thermal pack comprising a flexible, impervious outer container that is sealed to retain a liquid therein and capable of maintaining its sealed integrity when heated to at least 8o°C in a microwave oven, and a porous, non-rigid, absorbent filling located within the container that is capable of absorbing at least eight times its own weight of said liquid, wherein the outer container comprises a laminate of a stretch-resistant fabric and an impervious elastomeric polymer; and the non-rigid, absorbent filling comprises superabsorbent fibres adhered to a backing sheet.

Preferably, the liquid comprises water.

Preferably also, the liquid is present in a quantity by weight that is at least eight times the weight of the superabsorbent fibres. Advantageously, the weight of the liquid is up to twenty times the weight of the superabsorbent fibres.

Preferably also, the non-rigid filling includes absorbent woven or nonwoven textile material in addition to the superabsorbent fibres that are adhered to the backing sheet.

Other preferred but non-essential features of the present invention are described in the dependent claims appended hereto.

The present invention will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic representation of a thermal pack in accordance with the present invention;

Fig. 2 is a cross-section along the line II-II of the thermal pack shown in Fig, 1; and

Fig. 3 is a schematic cross-section of a laminate from which an outer container of the thermal pack shown in Figs. 1 and 2 is made.

An example of a thermal pack 1 in accordance with the present invention is shown in Figs. 1 and 2. It comprises an outer container 2 in the form of a pouch that is either made from a piece of material that has been folded and sealed around its edges 3 or made from two pieces of material sealed together around all of their edges 3. Contained within the outer container 2 is a non-rigid, absorbent filling 4 and a liquid 5 that in actuality is mainly absorbed into the filling 4 although in the drawing a quantity of the liquid is shown surrounding the filling 4 in the container 2.

It will be appreciated that although the pack 1 shown in Fig. 1 has a square shape, it could be made in any desired shape and therefore can be made to suit a part of the human or animal body it is intended to treat. For example, it could be made of a suitable shape and size to fit around the back of the neck, around a limb or across the back.

The non-rigid filling 4 comprises superabsorbent fibres 6 that are adhered to a backing sheet 7. Advantageously, however, and as is described in more detail below, the non-rigid filling 4 includes absorbent woven or nonwoven textile material 8 in addition to the superabsorbent fibres 6 and their backing sheet 7. The material 8 also absorbs the liquid sealed within the container 2. This liquid is primarily water and the weight of liquid used is at least eight times the weight of the superabsorbent fibres 6.

Whilst it maybe thought that a thermal pack wherein the non-rigid filling 4 is comprised solely of superabsorbent fibre material would allow production of the slimmest thermal packs, the applicant has found that such packs are difficult to fill in a manner that does not require excessive water, making the pack 1 too heavy to be practical. Alternatively, if filled with a lower weight of water, the water is not absorbed evenly by the non-rigid filling 4. Hence, preferably, the non-rigid filling 4 comprises up to 20% by weight of the superabsorbent fibres 6 and at least 80% by weight of the absorbent textile material 8. Such an arrangement enables the pack 1 to contain liquid 5 in a quantity that is up to twenty times the weight of the superabsorbent fibres 6 without making the pack 1 inflexible and heavy. For example, the pack 1 may contain a weight of liquid in the range 250 g to 1250 g·

The constituent parts of the pack 1 will now be described in more detail.

First, the container 1 is fashioned from a laminate 9, as shown in Fig. 3, that comprises a stretch-resistant fabric 10 and a layer of an impervious, elastomeric polymer 12. Preferably, the stretch-resistant fabric 10 comprises a woven fabric composed of nylon 6, 6 fibres that has been covered on both sides by the impervious elastomeric polymer, which comprises a polyethylene layer 12. Advantageously, the fabric 10 is also covered by a layer of ethylene-vinyl acetate (EVA) 11 that may be applied as a coating or adhered to the fabric 10 in sheet form. More particularly, the laminate 9 preferably comprises a five-layer laminate of woven nylon 6,6 fabric 10 that has been covered on each side by a layer of ethylene-vinyl acetate 11 that in turn has been coated or covered with polyethylene 12. The nylon fabric 10 has a melting point far in excess of temperatures that will be used during the construction and use of the pack 1, namely around 295°C and it has a high tensile strength, typically between 30 and 45 N/mm² inclusive along its warp and between 25 and 40 N/mm² inclusive along its weft so that it is stretchresistant and will not allow excess expansion of the pack 1 when it is heated.

The thickness of the laminate 9 used for the pack 1 is preferably of the order of 170 pm and has a weight that is of the order of 169.6 g/m². Such a laminate 9 is impermeable to water and water vapour and enables slim and flexible thermal packs 1 to be manufactured that are capable of being heated up to 8o°C without bursting or leaking. While the laminate 9 of the pack 1 can expand during heating it does not expand excessively, which can be problem with conventional packs, which inflate if overheated to the extent that they can become blocked in small microwave ovens. The laminate 9 is also capable of sustaining a seal that does not burst. As indicated above, the pack 1 is manufactured by sealing two pieces of the laminate 9 to one another to form a pouch. This is done by applying heat and pressure to appropriate edges 3 of what will become the pack 1, for example by using heated nip rollers, thereby fusing the outer polyethylene layers 12 of the laminate 9 together. Typically, the laminate 9 is heated to a temperature of between 12O°C and i6o°C to cause the fusing to occur. In use, however, the laminate 9 and therefore the pack 1 is capable of remaining stable if heated up to 120 °C provided that heating to this temperature is not continued for any length of time. However, for most purposes the pack 1 will not be heated in excess of 8o°C, which is a temperature that is safe for most therapeutic purposes and well below 12O°C above which the pack 1 could become unstable. The filling 4 is inserted into the pouch, to which the liquid 5 is then added and absorbed into the filling. The open mouth of the pouch is subsequently sealed to form the container 1. It will be appreciated that during this final sealing operation the pouch forming the container 2 is vacuum sealed and preferably is exhausted of air down to a pressure equal to 100 millibars or less so that the pack 1 does not expand when heated owing to significant air expansion.

Turning now to the non-rigid filling 4, this comprises the superabsorbent fibres 6 that are adhered to the backing sheet 7. Preferably, the fibres 6 comprise sodium polyacrylate fibres that have been evenly spread over and adhered to the backing sheet 7, which preferably comprises a thermoplastic polymer such as polyethylene. The backing sheet 7 holds the fibres 6 is place within the pack 1 to prevent their clumping together both during use and also during production of the pack 1 when the liquid is added to the pouch and the latter is sealed to form the container 1. The absorbent textile material 8 which is preferably also contained within the pack 1 is advantageously a conventional high-absorbency fabric, for example an airlaid nonwoven fabric derived from cellulosic fibres. This material 8 may be used in the form of strips, swatches, rolls, and shreds, or may be specifically shaped, formed or cut. Typically, it can absorb between five and eight times its own weight of liquid.

Finally, the liquid 5 is primarily water but advantageously it contains a preservative at a concentration capable of inhibiting microbial activity such as fungal and bacterial growth, which would detrimentally affect the pack 1 once it had been first filled with water. Such growth would reduce the shelf life of a pack to the extent of rendering it uncommercial and, once present, may present a health hazard to the user. The preservative may comprise any or a combination of sorbic acid, citric acid, propionic acid, chlorhexidine, chlorbutol, bronopol, phenoxyethanol, phenyl ethyl alcohol, an ester of para hydroxybenzoic acid, 2.4 dichlorobenzyl alcohol, polyhexanide, a phenolic compound, and a quaternary ammonium compound.

The external appearance of the pack 1 may be adapted to improve its tactile properties and heat transference, for example by the use of fixed or loose coverings.

In use, heating of the pack 1 is preferably accomplished using a microwave oven. However, as an alternative the pack 1 could be heated by immersion in hot water for a time sufficient to heat the pack 1 through. The example of pack 1 described above is capable of being immersed in water which is at or near boiling point for this purpose as it can withstand heating to ioo°C without deleterious effect.

As previously mentioned, it will be appreciated that the pack 1 is also capable of use as a negative heat pack, i.e. a cool pack, which can be used to abstract heat from live and inanimate subjects to which it is applied. In this case the pack would be cooled, conveniently by being placed in a refrigerator 10 or freezer for a predetermined period, before use as opposed to being heated in a microwave oven.

Claims

1. A thermal pack comprising a flexible, impervious outer container that is sealed to retain a liquid therein and capable of maintaining its sealed integrity when heated to at least 8o°C in a micro wave oven, and a porous, non-rigid, absorbent filling located within the container that is capable of absorbing at least eight times its own weight of said liquid, wherein the outer container comprises a laminate of a stretch-resistant fabric and an impervious elastomeric polymer; and the non-rigid, absorbent filling comprises superabsorbent fibres adhered to a backing sheet.

2. A thermal pack as claimed in Claim 1, wherein the liquid comprises water.

3. A thermal pack as claimed in Claim 1 or Claim 2, wherein the liquid is present in a quantity by weight that is at least eight times the weight of the superabsorbent fibres.

4. A thermal pack as claimed in Claim 3, wherein the weight of liquid is up to twenty times the weight of the superabsorbent fibres.

5. A thermal pack as claimed in any of Claims 1 to 4, wherein the stretchresistant fabric comprises fabric composed of nylon 6, 6 fibres.

6. A thermal pack as claimed in any of Claims 1 to 5, wherein the impervious elastomeric polymer comprises polyethylene.

7. A thermal pack as claimed in any of Claims 1 to 6, wherein the outer container comprises a five-layer laminate of the stretch-resistant fabric that has been covered on each side by a layer of ethylene-vinyl acetate, which in turn has been covered by a layer of polyethylene.

8. A thermal pack as claimed in Claim 7, wherein the outer container has been sealed by heat and pressure applied around its periphery to two adjacent sheets of the laminate thereby fusing the outer polyethylene layers together.

9. A thermal pack as claimed in any of Claims 1 to 8, wherein the stretchresistant fabric 10 comprises a woven fabric composed of nylon 6, 6 fibres.

10. A thermal pack as claimed in Claim 9, wherein the stretch resistant fabric has a tensile strength of between 30 and 45 N/mm2 inclusive along its warp and between 25 and 40 N/mm2 inclusive along its weft.

11. A thermal pack as claimed in any of Claims 1 to 10, wherein the superabsorbent fibres comprise sodium polyacrylate fibres spread over and adhered to the backing sheet.

12. A thermal pack as claimed in any of Claims 1 to 11, wherein the backing sheet comprises a thermoplastic polymer.

13. A thermal pack as claimed in Claim 12, wherein the backing sheet is comprised of polyethylene.

14. A thermal pack as claimed in any of Claims 1 to 13, wherein the nonrigid, absorbent filling includes absorbent woven or nonwoven textile material in addition to the superabsorbent fibres that are adhered to the backing sheet.

15. A thermal pack as claimed in Claim 14, wherein the absorbent woven or nonwoven textile material is comprised of cellulosic fibres.

16. A thermal pack as claimed in Claim 14 or Claim 15, wherein the nonrigid filling comprises up to 20% by weight of the superabsorbent fibres and at least 80% by weight of the absorbent woven or nonwoven textile material.

17. A thermal pack as claimed in any of Claims 1 to 16, wherein the liquid comprises a preservative at a concentration capable of inhibiting microbial growth.

18. A thermal pack as claimed in Claim 17, wherein the preservative comprises at least one of sorbic acid, citric acid, propionic acid, chlorhexidine, chlorbutol, bronopol, phenoxyethanol, phenyl ethyl alcohol, an ester of para hydroxybenzoic acid, 2.4 dichlorobenzyl alcohol, polyhexanide, a phenolic compound, and a quaternary ammonium compound.

19. A thermal pack as claimed in any of Claims 1 to 18, wherein the outer container has been vacuum sealed.

20. A thermal pack as claimed in Claim 19, wherein the outer container has been exhausted of air down to a pressure equal to 100 millibars or less.