WO1990005508A1

WO1990005508A1 - Improvements relating to heating devices

Info

Publication number: WO1990005508A1
Application number: PCT/GB1989/001369
Authority: WO
Inventors: Paul Spiller Wilkins
Original assignee: Paul Spiller Wilkins
Priority date: 1988-11-17
Filing date: 1989-11-17
Publication date: 1990-05-31
Also published as: GB2243300A; AU4659889A; CA2003285A1; GB2243300B; GB9110718D0

Abstract

A heating pad comprises an inner pouch (1) and an outer cover (2). The pouch (1) is formed from two sheets heat sealed together at their edges to enclose a heat retaining liquid with granules of ground up polyurethane foam material. The granules tend to act as heat stores so that when the liquid is heated the heating pad will give off warmth over a substantial period of time. The pouch (1) can readily be warmed by heating within a microwave oven, whereupon the relatively cool edge (7) of the pouch can be gripped to insert the pouch into the container (2) which is formed from a textile material with quilting lines (8). A connecting strip (9) will co-operate with a portion of a flap (10) so that the outer cover can be closed to protect the pouch (1).

Description

"Improvements Relating to Heating Devices"

This invention is concerned with the provision of heating devices which are particularly suited for use in heating the human body. A conventional hot water bottle comprises a flexible container of rubber or synthetic rubber with a filling aperture through which hot water is poured. Such bottles have a number of drawbacks. Thus it can be difficult for some people to fill the bottle safely from a hot water supply, there is always the risk that the outer surface of the bottle will become wet, and of course the bottle might leak or burst.

It is an object of this invention to provide a heating device which alleviates drawbacks present with conventional hot water bottles. According to the invention there is provided a heating pad comprising a heat-retaining base material formed from gel, wax or oil, within a sealed flexible container.

Such a heating pad can be preheated by subjection to microwave heating and, after removal, it will act as a heater for some time, as the base material retains its heat over a long period of time.

A wax-type base material will become liquid when heated. An example is paraffin wax. Oils may be chosen from vegetable, mineral or animal oils or any mixture. A gel-type base material might comprise a mixture of ethylene or propylene glycol, and methyl cellulose. Ideally a heat storage medium will be interspersed within the base material to help heat distribution and prevent rapid cooling. This medium might comprise fibres, threads or mesh structures of carbon fibre or other heat conductive material. An ideal medium material comprises foam particles of dust, crumb or granular nature of an insulation material, such as poly¬ ester, polyurethane, other polymer or silica.

A stabiliser, such as a thickening agent might also be incorporated. In a particular preferred arrangement the base material will comprise glycerine together with a thickening agent with granules of a polyurethane foam interspersed therein. The thickening agent could comprise methyl-cellulose paste or polyacryloamide.

Another possibility is to use wax instead of the glycerine with or without the thickening agent and/or the foam granules. A mixture of wax and glycerine may be used. Furthermore wax and/or glycerine may be employed in combination with liquid absorbtion granules

(commonly used for waste absorbtion) . In this instance the mixture may comprise two parts of wax or glycerine to one part of granules. A further possibility is a coπbination of wax/and or glycerine together with china clav, acting as the heat storage medium.

All of these mixtures provide good heat retention qualities whilst minimising problems which may occur due to expansion as a material is heated up in a microwave oven or even in a conventional oven.

If the base material incorporates an additive having a bitter taste and/or a distasteful colour, this will reduce the possibility that a child may attempt to eat the base material. In any event it is preferred that the materials used within the container should be non- toxic.

Another preferred additive is a heat sensitive material which changes colour once a predetermined te p- erature has been achieved. This enables the user to note when the pad has heated up as required. The heat sensitive material could be a heat sensitive dye mixed into the base material, the flexible container then being translucent, so that the colour change can be noted. As an alternative, a heat sensitive colour change strip, or some other temperature indicator could be mounted on the outside of the container.

If the base material is likely to produce gas upon being heated, then the heating pad may be so formed as to allow for expansion of gas within the base material as a result of heating of the base material, whilst preventing loss of the base material and gas from the container. Retention of any gas within the body of the container at all times allows the cooled gas to be reabsorbed into the base material so that, after several uses the base material will not become dried out and solidified. One construction which allows for the expansion and retention of gas comprises a container which has two interconnected sections with a filter or relief valve therebetween, which allows gas but not the base material to pass therethrough. An alternative, or additional possibility is for the container to incor¬ porate an absorbent layer which will selectively absorb the gas. Another option is for the container to incorporate sufficient free space, or be expandable itself, to take up the expanded gas.

The container may be in the form of a sealed pouch of natural or synthetic rubber, with edges sealed by heat welding, radio frequency welding, glueing or press¬ ing, for example. Suitable materials might be polymers o in the form of polyester, polypropylene, nylon and polythene or elastomers, such as EPDM, varnac, silicon rubber, viton, ptfe, possibly with silicon or glass fibres interspersed for added strength and heat charac¬ teristics. An outer stitched safety cover made, for 5 example, from a waterproofed material, such as cotton coated in ptfe, or nylon or polyester, or a material with a high melting point (in excess of 150°C) could also be used to cover the pouch before being placed in an outer textile cover. The sealed pouch could be of a honeycomb design to provide desirable heat dissipation, with a sealed filling point.

A textile cover preferably of a fire retardant material will ideally be provided for retaining the flexible container, and if desired the textile cover can be partially heat insulating to allow for gentle heat dissipation. Perforation of the cover and/or quilting can aid the escape of heat in a controlled way. The cover could, for example, incorporate a shredded heat reflecting material. However if it is intended that the textile cover should not normally be removed from the container, metal parts must be avoided if the unit is to be heated in a microwave oven.

The heating pad can be made to any desired shape, capable of fitting into a microwave heater such as square or rectangular, but preferably with rounded edges. For heating particular parts of the body, special shapes could be provided, such as tubes or rings to act as bands for sliding over limbs. Of course various novelty shapes, such as of toy animals might be formed. The cover could have adjustable straps to allow the device to be attached to part of the body.

It should be noted that the base material might be of a j elly-like ^• matrix which is heat- receptive , such as by microwave radiation , and which retains its j elly-like state , hen heated . Another heating poss ibility is to provide a base material in the form of a known chemical mix or gel which will heat up when subj ected to an electrical charge through a supply lead to the device .

The device might be used for cooling purposes , for example to keep food or drinks cool , in which case the base material may incorporate an antifreeze material or something s imilar and s haped to f it around t he art icle to be cooled .

The invention may be performed in various ways and preferred embodiments thereof will now be described, with reference to the accompanying drawings, in which:- Figure 1 is a perspective view of the preferred form of heating pad of this invention;

Figure 2 is a vertical section through the inner pouch of the heating pad of Figure 1;

Figure 3 is a perspective view of the alternative form of inner pouch; and

Figure 4 is a perspective view of an alternative form of heating pad of this invention.

The heating pad shown in Figures 1 and 2 comprises an inner pouch 1 and an outer cover 2. The pouch 1 is formed from two sheets 3 and 4 of polyproplene or a nylon and polyester mix heat sealed together at their edges to enclose a heat retaining liquid 5. The liquid 5 in this example comprises a vegetable oil together with a mineral oil as a stabilizer, with granules 6 of ground up polyurethane foam material. The granules 6 tend to act as heat stores so that when the liquid 5 is heated the heating pad will give off warmth over a substantial period of time. The granules also act as a means of absorbing the gel liquid, should the pouch perish or be punctured. This is a safety feature since large volumes in the region of 500 grams of very hot liquid would not escape to cause massive burns of the body because the granules would absorb that liquid, unlike a conventional hot water bottle. Vegetable oil has the advantage that it will not heat up to an extreme temperature too rapidly and the structure of the gel remains more stable than a glycerine and glycol mixture which would also reach boiling point more quickly so that the heating pad might become uncomfortably hot.

The pouch 1 could readily be warmed by heating within a microwave oven, whereupon the relatively cool edge 7 of the pouch could be gripped to insert the pouch into the container 2 which is formed from a textile material with quilting lines 8. A connecting strip 9 will co-operate with a portion of a flap 10 so that the outer cover could be closed to protect the pouch 1.

An alternative form of the oouch 2 is shown in Figure 3. This is an enclosed container but formed as a honeycomb construction with passageways 12 passing therethrough. A filling aperture 13 is provided which will be heat sealed once the pouch has been filled with the heat retaining material.

A further form of heating pad as shown in Figure 4 has an enlarged flap 10A which will be folded into the outer cover 2A after the pouch 1A has been inserted, thus securely retaining the pouch and preventing a part of the body of the user from coming accidentally into direct contact with the pouch. The outer cover 2A in this example is made from a fire retardent polyester material as a filling, with a cotton quilted cover. A hanging tag 14 is provided.

Claims

CLAI S

1. A heating pad comprising a heat-retaining base material, preferably of a non-toxic nature formed from praffin wax or other wax, vegetable, mineral or animal oils, or any mixture thereof, or a gel type material, within a sealed flexible container.

2. A heating pad according to claim 1, wherein a heat storage medium is interspersed within the base material and preferably comprises fibres, threads or mesh structures of carbon fibre or other heat conductive material, or ideally foam particles of dust, crumb or granular nature of an insulation material, such as poly¬ ester, polyurethane, other polymer or silica.

3. A heating pad according to claim 1 or claim 2, including a stabiliser, such as methyl-cellulose paste or polyacryloaπide or other thickening agent.

4. A heating pad according to any one of claims 1 to 3, wherein the base material comprises ---glycerine , wax or a mixture of wax and glycerine, together preferably with china clay or with a thickening agent, with granules of a polyurethane foam or liquid absorption granules interspersed therein, or a mixture of ethylene or propylene glycol, and methyl cellulose.

5. A heating pad according to any one of claims 1 to 4, wherein the base material incorporates an additive having a bitter taste and/or a distasteful colour, and/or an antifreeze material, and/or a heat sensitive material which changes colour once a predetermined temp¬ erature has been achieved, a heat sensitive dye mixed into the base material, the flexible container then being translucent, so that the colour change can be noted, and/or a heat sensitive colour change strip, or some other temperature indicator is mounted on the outside of the container.

6. A heating pad according to any one of claims 1 to 5, formed so as to allow for expansion of gas within the base material as a result of heating of the base material, whilst preventing loss of the base material and gas from the container, such as by forming the container with two interconnected sections with a filter or relief valve therebetween, which allows gas but not the base material to pass therethrough, or incorporating within the container an absorbent layer which will selectively absorb the gas, or forming- the container with sufficient free space, or be expandable itself, to take up the expanded gas.

7. A heating pad according to any one of claims 1 to 6, wherein the container is in the form of a sealed pouch of natural or synthetic rubber, such as polymers in the form of polyester, polypropylene, nylon and polythene or elastomers, such as EPDtl, varnac, silicon rubber, viton, ptfe, possibly with silicon or glass fibres interspersed for added strength and heat charac¬ teristics, with edges of the pouch sealed, for example, by heat welding, radio frequency welding, glueing or pressing, with, optionally, an outer stitched safety cover made, for example, from a waterproofed material, such as cotton coated in ptfe, or nylon or polyester, or a material with a high melting point.

8. A heating pad according to any one of claims 1 to 7, wherein a textile cover, preferably of a fire retardant material, is provided for retaining the flex¬ ible container, the textile cover ideally being part¬ ially heat insulating to allow for gentle heat dissip¬ ation, such as of a perforated or quilted nature, and possibly incorporating a shredded heat reflecting material, the cover advantageously having a closure flap and/or adjustable straps.

9. A heating pad according to any one of claims 1 to 8, made to a predetermined shape, capable of fitting into a microwave heater such as square or rectangular, but preferably with rounded edges, or as a tube or ring to act as a band for sliding over a limb, or in a novelty shape, or as a honeycomb design with a sealed filling point.

10. A heating pad according to any one of claims 1 to 9, including integral heating means, such as bv providing the base material in the form of a chemical mix or gel which will heat up when subjected to an electrical charge through a supply lead to the device.