GB2261438A - Composite thermal reservoir employing solid, pliable organic compound - Google Patents

Abstract

A composite thermal reservoir material includes a substrate of fabric material secured to a substrate of a solid, dry, pliable organic compound containing a hydroxyalkylcellulose compounded with an alkylene glycol. Best results are obtained in a formulation comprising about 4 parts by volume of hydroxyethylcellulose and about 3 parts by volume of propylene glycol. The resultant organic compound is non-toxic, solid, non-tacky, dry and moldable into a solid structural form. A free-flowing, unconsolidated thermal reservoir material is produced by mixing about 2 parts by volume hydroxyethylcellulose with about 1 part by volume propylene glycol and about 1/4 part by volume bicarbonate of soda.

Description

"COMPOSITE THERMAL RESERVOIR EMPLOYING SOLID, PLIABLE ORGANIC COMPOUND" The present invention relates generally to body-warming and body-cooling devices, and in particular to such devices which utilize passive thermal energy storage materials.

Body-warming and body-cooling devices are known for application to a person's hands, head, ears and back to provide warmth or cooling for comfort and for therapeutic purposes. For example, heating pads, ice packs and cold compresses are used for such purposes. Some hot and cold packs include a liquid solution or gel material sealed within a flexible container for storing thermal energy. Such containers may burst in response to overheating. In the event the container should rupture, the hot liquid or gel material will leak and may cause burn injury to the user. Moreover, in the event such a liquid or gel material should be used in a cold pack, there is a risk that the container may rupture upon being frozen, thereby permitting the liquid or gel material to leak upon thawing.

Various structures are known in which the thermal reservoir material may be packaged, such as a jacket (U.S. Patent 2,403,676), and various shapes that the envelope container may take, such as a compressed shape to conform to the forehead of a person (U.S.

Patent 1,964,655), and a glove (U.S. Patent 2,515,298).

A limitation on the use of such conventional body-warming and body-cooling devices is that a sealed container must be provided, and the liquid or gel material is subject to leakage should the container rupture or be punctured. Some thermal storage materials are toxic or corrosive. Moreover, the liquid or gel thermal material is not capable of maintaining a desired form or structure, and must be encapsulated or otherwise supported by a rigid container to maintain a desired shape.

Accordingly, a need exists for a dry, thermal reservoir material which may be frozen or heated and which will not burst, explode, burn, melt or drip when heated above the boiling point of water, or cooled below the freezing point of water. Moreover, a thermal reservoir material is needed which can be molded into various structural forms, and which will maintain its molded form after curing, making it suitable for bodycooling as well as body warming applications. A dry thermal reservoir fabric material suitable for both hot and cold service, which is soft and pliable, as well as being non-toxic, is needed for use in combination with various fabric items, for example, earmuffs, hats, gloves, socks, shoes, boots, coats, stuffed toys, pillows, beverage coolers, food warmers, refrigerated chests, heating pads, cooling pads, blankets, quilts and the like.

The present invention provides a composite thermal reservoir material in which a fabric substrate is secured to a solid, organic substrate consisting of (a) a hydroxy-C.5 alkyl-cellulose (preferably hydroxyethylcellulose) and (b) a As alkylene glycol (preferably propylene glycol) or the condensation product thereof.

The cured material provides a dry, solid core material which may be molded into any desired shape, and is nontoxic. More specifically, the organic thermal reservoir composition of the invention is produced by mixing about three parts by volume of propylene glycol with about four parts by volume of hydroxyethylcellulose. During the reaction, an OH group on a carbon atom of the hydroxyethylcellulose molecule condenses with an OH group on the propylene glycol molecule. Water (H2O) is a reaction by-product which is removed during curing.

The resultant organic compound is non-toxic, solid, nontacky, dry and moldable into a solid, pliable structural form.

An unconsolidated thermal padding material is produced by mixing about 2 parts by volume hydroxyethylcellulose with about 1 part by volume propylene glycol and about 1/4 part by volume bicarbonate of soda.

The bicarbonate of soda causes the compound to particulate, thereby producing a thermal reservoir padding material for various applications which require thermal stuffing material.

A low density thermal reservoir material is provided by combining about 1 part by volume hydroxyethylcellulose with 1 1/2 parts by volume propylene glycol, 1/8 part by volume 1, l'-azodicarbonamide (a blowing agent), preferably CELOGEN trademark of Uniroyal Chemical Company, and 1/8 part by volume CARBOPOL, a blend of water soluble resins having gel forming properties, manufactured by B.F. Goodrich Chemical Company.

This yields a non-toxic, lightweight thermal reservoir material which may be attached to fabric material by various methods, for example, by stitching, stapling, adhesives and thermal welding.

A liquified formulation which can be used as a coating for a thread or fabric is provided by combining about 2 partes by volume hydroxyethylcellulose with about 3/4 part propylene glycol, 1/26 part by volume bicarbonate of soda and 1/13 part CELOGEN. The liquid formulation penetrates the fibers of the thread, and upon curing, the thread is encapsulated by a tubular jacket of the thermal reservoir material. The thread is then woven to produce a fabric having good heat retention capability.

Other features and advantages of the present invention will be appreciated by those skilled in the art upon reading the detailed description which follows with reference to with the attached drawings, wherein: FIGURE 1 is a graph of sample temperature (OF) as a function of time which represents the heat retention capabilities of first and second sample compositions of the preferred formulation; FIGURE 2 is a graph of sample temperature (OF) as a function of time which illustrates the cold retention properties of said first and second sample compositions; FIGURE 3 is a graph of sample temperature (OC) as a function of time showing the heat retention characteristics of the first and second sample compositions including internal and external insulation means;; FIGURE 4 is a graph of sample temperature (roc) as a function of time within a water calorimeter during a determination of the specific heat of the organic thermal reservoir material of the preferred formulation; FIGURE 5 is an enlarged sectional view of a layer of fabric material bonded to a layer of thermal reservoir material formulated according to the present invention; FIGURE 6 is an enlarged sectional view of a layer of fabric material which is sandwiched between two layers of thermal reservoir material having the composition of the present invention; FIGURE 7 is an enlarged sectional view of a core of thermal reservoir material sandwiched between first and second layers of fabric material, and being secured by stitching; and, FIGURE 8 is a view similar to FIGURE 7 in which the fabric layers are secured to the thermal reservoir material by a thermal weld.

According to one aspect of the present invention, a fabric substrate is secured to a substrate of organic thermal reservoir composition which includes, as its active ingredients, hydroxyethyl-cellulose and propylene glycol. Satisfactory results for molded applications have been obtained by compounding from about 20% to about 40% part by volume of propylene glycol with about 60% to about 80% part by volume of hydroxyethylcellulose. The best results for molded applications have been obtained by compounding three parts by volume of propylene glycol with four parts by volume of hydroxyethylcellulose.

Other cellulose derivatives may be used to good advantage in the formulation of the present invention, for example, hydroxypropylcellulose and other glycols, for example, ethylene glycol may be used as a substitute for propylene glycol. The preferred formulation of the organic compound comprises generally (a) a hydroxyalkylcellulose containing 1 to 5 carbon atoms in the alkyl radical and (b) an alkylene glycol containing 2 to 5 carbon atoms in the alkyl radical, or a condensation product of components (a) and (b).

The preferred formulations for molded (consolidated) embodiments of the present invention are combined in the following proportions: VOLUME PERCENT - CONSOLIDATED COMPONENT SUITABLE PREFERRED MOST PREFERRED PROPYLENE GLYCOL 20-40 25-35 25 HYDROXY ETHYLCELLULOSE 60-80 65-75 75 The preferred formulation of the consolidated embodiment is preferably made in a batch process as follows: The ingredients are placed in a vessel such as a stainless steel mixing tank. Hydroxyethylcellulose powder is placed in the tank and then liquid propylene glycol is poured into the tank in the preferred proportions as set forth above. The mixture is then agitated by suitable means such as a stirrer. Stirring is continued until a smooth, homogenous mixture is obtained. Thereafter, the mixture is placed in a suitable container having a desired form, or in the cavity of a mold.The mixture is then cured by baking in an oven at 1100 - 1700F (430C - 760C) until the water by-product has been substantially removed. Alternatively, the mixture is cured by irradiating it in a microwave oven.

According to an unconsolidated embodiment, the reaction mixture of propylene glycol with hydroxyethylcellulose does not require the application of heat or curing. The resulting mixture has a dry, crumbly consistency and has an average size comparable to the size of bread crumbs. This dry, unconsolidated mixture is well suited for use as a stuffing material. Best results for producing an unconsolidated crumbly mixture for stuffing applications has been obtained by compounding one part by volume of propylene glycol with two parts by volume of hydroxyethylcellulose.

The preferred formulations for the dry, unconsolidated stuffing material embodiment of the present invention are combined in the following proportions: VOLUME PERCENT - UNCONSOLIDATED COMPONENT SUITABLE PREFERRED MOST PREFERRED PROPYLENE GLYCOL 25-40 25-35 33 HYDROXY ETHYLCELLULOSE 60-75 65-75 67 In order to provide a better understanding of the present invention including representative advantages and limitations thereof, the following referential examples are offered as related to certain tests performed in the practice of this invention, and illustrate the excellent heat retention and cold retention properties of the preferred formulations, as follows: Example 1 A 42 gram (1.5 oz) sample 10 of the preferred formulation was prepared by reacting three parts by volume of propylene glycol with four parts by volume of hydroxyethylcellulose.The sample was cured and thereafter shrink wrapped in one thickness of .52 mil (.013 mm) plastic film. The bulb of a mercury thermometer was embedded within the sample. The temperature within the test facility was maintained constant at 740F (230C) throughout the test, and was free from draft.

The sample 10 was heated in an oven until an initial temperature of 1880F (860C) was produced as illustrated by the curve 10 in FIGURE 1. It was then allowed to cool at room temperature (740F, 230C) and the rate of cooling was determined by recording the indicated temperature of the sample at 5 minute intervals during a 45 minute period.

After 5 minutes, the sample 10 had cooled to 1760F (800C). After 10 minutes, the indicated temperature of sample 10 was 1700F (760C). The most substantial decline occurred during the interval 10 minutes to 15 minutes, in which the temperature dropped by 280F to 1420F (610C). The decline remained consistent with no more than a 40F decline per 5 minute interval during the remainder of the test. After 45 minutes had elapsed, the temperature of sample 10 had dropped to 102 OF (39 C).

The sample 10 was tested a total of 6 times, with the temperature measurements being recorded at 5 minute intervals during each test. Each time, the sample 10 was heated to an initial temperature of about 1870F (860C), with the indicated temperature of the respective readings varying by no more than about 30F, and having an average variation of about 10F per reading.

In summary, sample 10 decreased in temperature by a total of 860F (30 C) in 45 minutes or at an average rate of l.90F per minute. The average rate of heat loss was at a rate of l.lOF per minute during the last 25 minutes of the test.

Example 2 The curve designated 20 in FIGURE 1 repre sents the rate of heat loss for a 42 gram (1.5 oz) sample 20 of the preferred mixture of propylene glycol and hydroxyethylcellulose in the proportions as set forth in Example 1. The sample 20 was blended and cured following the same procedure of Example 1. The sample 20 was first wrapped in a single thickness of 0.125 inch (3 mm) poly fill plastic film, and was then wrapped within two thicknesses of .52 mil (13 mm) plastic film.

The sample 20 was heated for 40 seconds in a microwave oven to a temperature of 1980 F (920 C).

The sample 20 was tested a total of 6 times, with the temperature measurements being recorded at 5 minute intervals. Each time, the sample 20 was heated to an initial temperature of about 1980 F (920 C), with the indicated temperatures of the respective readings varying by no more than about 30 F per reading, and having an average variation of about 10 F per reading.

It will be noted that the average rate of heat loss of sample 20 was substantially lower during the interval of 10 minutes to 30 minutes as compared with the sample 10 which had only a single wrapping of plastic film.

Example 3 Referring to FIGURE 2, a 5 ounce (140 grams) sample 30 of the preferred formulation was prepared by reacting three parts by volume of propylene glycol with four parts by volume of hydroxethylcellulose as set forth above in Example 1. Ambient temperature was maintained constant at 850 F (290 C). The temperature reading was taken at 5 minute intervals with a thermometer embedded within the sample 30. The performance of the cured formulation given above is indicated by the curve 30. The sample was initially cooled to a temperature of 120 F (-110 C), and was then placed in a room at ambient 850 F (290 C) which was free from draft.

The curve 30 shows that the average rate of heat gain was 0.70 F per minute during the first 60 minute of the test, and was only 0.250 F per minute during the next 60 minutes of the test.

The sample 30 was tested a total of 6 times, with the temperature measurements being recorded at 5 minute intervals. Each time, the sample 20 was cool,ed to an initial temperature of about 120 F (-110 C), with the indicated temperatures of the respective readings varying by no more than about 30 F per reading, and having an average variation of about 10 F per reading.

Example 4 Referring again to FIGURE 2, a 5 ounce (140 grams) sample 40 was prepared by adding one part by volume purified water to two parts by volume propylene glycol and four parts by volume of hydroxyethylcellulose. The sample was not cured, but was instead immediately chilled to a temperature of 60F (-140 C).

The average rate of heat gain during the first 60 minutes of the test for sample 40 was 0.550F per minute, and the average rate of heat gain during the second 60 minutes was 0.350F per minute.

The sample 40 was tested a total of 6 times, with the temperature measurements being recorded at 5 minute intervals. Each time, the sample 40 was cooled to an initial temperature of about 50 F (-15 C), with the indicated temperature of the respective readings varying by no more than about 30 F per reading, and having an average variation of about 10 F per reading.

The room temperature in which the sample 40 tests were conducted was maintained constant at 850 F (290 C).

Example 5 Referring now to FIGURE 3, a 4 ounce (112 grams) sample 50 of the preferred formulation was prepared according to the method and proportions given in Example 1. The sample 50 was insulated on one side by a fabric jacket having a thickness of approximately 5 mils (0.125 mm) to simulate a heat pad. The curve designated 50 in FIGURE 3 illustrates the heat loss performance of sample 50 which used as a heat pad. The exposed side of the heat pad was placed onto the body of a subject having a body weight of 185 pounds (83 kg) and a body temperature of 98.60 F (370 C). The heat pad sample 50 was applied to the subject immediately after removal from the oven. The temperature reading was taken ever 5 minutes. The room temperature was main tained constant at 770 F (250 C).

The sample 50 was tested a total of 6 times, with the temperature measurements being recorded at 10 minute intervals. Each time, the sample 50 was heated to an initial temperature of about 1150 F (460 C), with the indicated temperatures of the respective readings varying by no more than about 20 C per reading, and having an average variation of less than 10 C per reading.

The average rate of heat loss for the heat pad sample 50, while placed in contact with a subject having a body temperature of 98.60 F (370 C), was 0.10 C per minute.

Example 6 Referring again to FIGURE 3, a sample 60 was prepared using the preferred proportions set forth above, and was molded in the shape of a rectangular pad.

The pad sample 60 was sandwiched between two sheets of styrofoam having a thickness of 0.75 inch (19 mm) A thermometer was embedded within the sample.

The heat loss negligible during the first 80 minutes of the test. The sample 60 temperature dropped substantially at an average rate of 0.380 C per minute during the last 80 minutes of the test.

The sample 60 was tested at a total of 6 times, with the temperature measurements being recorded at 20 minute intervals. Each time, the sample 60 was heated to an initial temperature of about 1710 F (770 C), with the indicated temperature of the respective readings varying by no more than about 20 C per reading, and having an average variation of less than about 10 C per reading.

Example 7 Referring now to FIGURE 4, a 5 gram (0.175 ounce) sample 70 of the preferred formulation was prepared according to the procedure and proportions of Example 1. The sample 70 was placed within a sealed metal container within 100 grams (3.5 ounce) of water in a water calorimeter. The water in the calorimeter and the sample 70 was preheated to an initial temperature of 770 F (250 C). The temperature rise from about 77O (250 C) to about 810 F (270 C) occurred over a 2 minute interval as indicated by the curve 70. Two hundred calories of thermal energy were input to the calorimeter to raise the temperature of the sample 70 from 770 F (250 C) to 810 F (270 C), thereby indicating a specific heat value of 20 for the preferred formulation.

Example 8 In this example, a 5 ounce (140 grams) sample 80 of the preferred formulation was prepared according to the procedure and proportions of Example 1. Prior to curing, a 1 ounce (28 grams) of particulated styrofoam was mixed with the 5 ounces (140 grams) of formulation.

The 6 ounce (168 grams) sample 80 containing the particulated styrofoam was then cured in an oven as set forth in Example 1. The sample 80 was shrink wrapped in one thickness of .52 mil (13 mm) plastic film. The bulb of a mercury thermometer was embedded within the sample.

The temperature within the test facility was maintained constant at 740 F (230 C) throughout the test, and was free from draft. The sample was heated in an oven to an initial temperature of 2000 F (93 C). It was then allowed to cool at ambient room temperature 740 F (230 C). The sample 80 decreased in temperature at an average rate of 1.20 F per minute, and was relatively linear as compared with the performance of samples 10 and 20.

Example 9 A 5 ounce (140) grams) sample 90 of the preferred formulation was prepared according to the procedure and proportions set forth in Example 1. After curing the 5 ounce (140 grams) sample was particulated into irregular granules having a average length of .3 cm - .5 cm. Five ounces (140) grams) of expanded, cellular polystyrene granules having substantially the same diameter size (.3 cm - .5 cm) was then thoroughly mixed with the formulation granules. The 10 ounce (280 grams) mixture formulation and polystyrene granules was then shrink wrapped in one thickness of .52 mil (13 mm) plastic film. The bulb of a mercury thermometer was embedded within the sample 90. The ambient temperature within the test facility was maintained constant at 740 F (230 C) throughout the test, and was free from draft.

The sample 90 was heated in an oven until an initial temperature of 1800 F (82 C) was produced. The sample 90 was then allowed to cool at room temperature 740 F (23 C) and the rate of cooling was determined by reading the indicated temperature of the sample 90 at 5 minute intervals over a 45 minute period. The sample 90 decreased in temperature at an average rate of 0.90 F per minute. The average rate of loss was at a rate of 0.60 F per minute during the last 25 minutes of the test.

Example 10 About 1 part volume hydroxyethylcellulose and about 1/2 part by volume propylene glycol was mixed with about 2 parts by volume of polyester fibers. Upon curing, the result was a consolidated stuffing material which was used as padding in various fabric products such as pillows, toys, quilts and the like.

Example 11 An unconsolidated formulation was prepared to produce a thermal reservoir stuffing material. In this formulation, about 2 parts hydroxyethylcellulose was combined with about 1 part propylene glycol and about 1/4 part bicarbonate of soda. The resulting formulation was characterized by a free-flowing lumps or nodules having diameter sizes ranging from about 0.5 cm to about 1.5 cm. The free-flowing thermal reservoir nodules were used as padding and stuffing material in various articles of clothing such as vests, mittens, scarfs, headbands, shoes, bedding and the like.

Example 12 In this example, a consolidated formulation was prepared according to the procedure of Example 1 and with the following ingredients: about 1 part by volume hydroxyethylcellulose mixed with about 1 1/2 parts by volume propylene glycol, about 1/8 part by volume CELOGEN and about 1/8 part by volume CARBOPOL. The resulting formulation was placed in a mold and formed a solid layer upon curing.

Example 13 In this example, a lightweight, consolidated formulation was prepared according to the procedure of Example 1 and with the following ingredients: about 1 part by volume hydroxyethylcellulose, about 3/4 part by volume propylene glycol, about 1/4 part bicarbonate of soda and about 1/26 part by volume of a blowing agent, 5-PHENYLTETRAZOLE manufactured by Uniroyal Chemical Company under the trademark EXPANDEX. The blowing agent produced closed air cells within the solid core, thereby reducing its weight and density.

Example 14 A liquified formulation was prepared for application to textile fibers. This formulation was prepared according to the following proportions: about 2 parts by volume hydroxyethylcellulose, about 3/4 part by volume propylene glycol, and 1/26 part bicarbonate of soda and 1/13 part 1,1'-azodicarbonamide, which is available from the Uniroyal Chemical Company under the trademark CELOGEN. The resulting liquified formulation was mixed with fibers prior to spinning to produce thread. Alternatively, the liquid formulation was applied as a coating to the thread, which after curing provided a jacket of thermal reservoir material about the thread.

Referring now to FIGURE 5, a layer 100 of consolidated thermal reservoir material prepared according to Example 12 is bonded to a layer 110 of fabric material. Bonding may be obtained by an adhesive deposit, or by flame lamination.

Referring to FIGURE 6, the layer 110 of fabric material is embedded within a unitary substrate of thermal reservoir material 100 prepared according to Example 14. Preferably, the thermal reservoir material is liquified and is applied as a coating to the fabric material 110, with the liquified thermal reservoir formulation penetrating the woven fabric material.

Referring to FIGURE 7, a layer of consolidated thermal reservoir material 100 prepared according to Example 10 is sandwiched between an upper fabric layer 110 and a lower fabric layer 112. The composite assembly is stabilized by stitches 114, 116.

Referring now to FIGURE 8, a layer 100 of consolidated thermal reservoir material is secured between first and second textile fabric layers 110, 112.

The first and second textile layers are sealed together along the peripheral edges by thermal welds 118, 120.

Other consolidated formulations were prepared and tested, with the volume ratio of propylene glycol to hydroxyethylcellulose being varied through the range of 20% to 40% for propylene glycol and 60% to 80% for hydroxyethylcellulose. Marginal heat gain/heat loss performance was noted for the proportion 40% - propylene glycol, 60% hydroxyethylcellulose. The volume ratio of 25% - 35% propylene glycol and 65% - 75% hydroxyethylcellulose provided acceptable to good heat loss/heat gain performance. The best results for molded (consolidated) product applications, however, were provided by the volume ratio of 3 parts propylene glycol to 4 parts hydroxyethylcellulose. The resulting product, in all of the formulations, was curable to a dry, solid, pliable composition which was non-toxic and non-tacky.

Other stuffing (unconsolidated) formulations were prepared and tested, with the ratio of propylene glycol to hydroxyethylcellulose being varied through the range of 25-40 volume percent for propylene glycol and 60 - 75 volume percent for hydroxyethylcellulose.

Marginal heat gain/heat loss performance was noted for the proportion 40% by volume propylene glycol, 60% by volume hydroxyethycellulose. The volume ratio of 25% 35% propylene glycol and 65% - 75% hydroxyethylcellulose provided acceptable to good heat loss/heat gain performance. The best results for stuffing material product applications, however, were provided by the volume ratio of about 1 part by volume propylene glycol to about 2 parts by volume hydroxyethylcellulose. The resulting product was dry, solid, unconsolidated, crumbly particles approximately the size of bread crumbs which were self-curing when reacted, and did not require heating.

The hydroxyethylcellulose used in the foregoing consolidated and unconsolidated formulations is preferably of cosmetic grade. Cosmetic grade hydroxyethylcellulose may be obtained from Aqualon Corporation of Wilmington, Delaware under the brand name NATRASOL.

The propylene glycol utilized in the foregoing formulations is preferably purified and non-toxic food grade.

It can be obtained from commercial suppliers of chemical formulations, for example, Ashland Chemical Company of Dallas, Texas.

The heat retention capability of the formulations was enhanced by blending a thermal insulation material such as styrofoam in the formulation before curing, or within the particulated formulation after curing.

The compositions of the present invention have proven effective as a thermal reservoir material for body-warming and body cooling devices. The compositions can be used with or without any type of outside sealing container or envelope, and can be used in combination with various fabric covered body-warming and bodycooling products, including, but not limited to earmuffs, hats, gloves, socks, shoes, boots, coat, terry cloth garments, head and neck scarves and also in a wide variety of stuffed fabric products including, but not limited to toys and pillows, as well as therapeutic devices such as back braces, heating pads, hot compresses and cold compresses. The consolidated formulation can be poured into a mold, and after being heated and cooled, retains its size and shape during both hot and cold service.Moreover, the consolidated formulation can be formed in sheets or layers and applied as a lamination to fabric material as shown in FIGURES 5, 7 and 8. Additionally, fabric material can be embedded within the consolidated formulation prior to curing as shown in FIGURE 6, thereby producing a composite material having good heat retention and may be used to good advantage, for example, in the construction of quilts and blankets.

The components of the foregoing formulations are non-toxic, biodegradable and may be heated to a desired temperature in a microwave oven or frozen to temperatures well below zero without damage or performance degradation. Accordingly, the formulations of the present invention are safe for use in consumer products, and in particular for products intended for use by children. Moreover, the consolidated formulation can be molded into any desired shape, thereby making it well suited for diverse applications, for example, heated and chilled beverage holders.

The above volume ratios and reaction conditions have been provided for illustration purposes only.

As those skilled in the art will recognize, it is likely that acceptable thermal reservoir material can be produced using reaction ratios and conditions different from the preferred values given above.

TABLE I

Claims (18)

1. A composite thermal reservoir comprising a substrate of fabric material secured to a body of thermal reservoir material, wherein the thermal reservoir material comprises (a) a hydroxyalkylcellulose containing 1 to 5 carbon atoms in the alkyl radical and (b) an alkylene glycol containing 2 to 5 carbon atoms in the alkyl radical, or a condensation product of components (a) and (b).

2. A composite thermal reservoir as defined in Claim 1, wherein the substrate of fabric material is embedded within the body of thermal reservoir material.

3. A composite thermal reservoir as defined in Claim 1, wherein said body of thermal reservoir material is sandwiched between first and second fabric substrates.

4. A composite thermal reservoir as defined in claim 3, wherein the first and second fabric substrates are secured to the body of thermal reservoir material by a stitched thread.

5. A composite thermal reservoir as defined in claim 3, wherein the first and second fabric sub strates are secured to the body of thermal reservoir material by adhesive bonding.

6. A composite thermal reservoir as defined in claim 3, wherein marginal edge portions of the first and second fabric substrates are sealed together by a thermal weld.

7. A composite thermal reservoir as defined in any one of claims 1 to 6, wherein the hydroxyalkylcellulose comprises hydroxypropylcellulose and the alkylene glycol comprises ethylene glycol.

8. A composite thermal reservoir as defined in any one of claim 1 to 6, wherein the hydroxyalkylcellulose comprises hydroxyethylcellulose and the alkylene glycol comprises propylene glycol.

9. A composite thermal reservoir as defined in any one of claims 1 to 8, wherein said fabric substrate comprises an unconsolidated volume of textile fibres.

10. A composite thermal reservoir as defined in claim 9, wherein the hydroxyalkylcellulose comprises about 1 part by volume hydroxyethylcellulose, the alkylene glycol comprises about 1/2 part by volume propylene glycol, and the textile fibres comprise about 2 parts by volume of mixture.

11. A composite thermal reservoir as defined in any one of claims 1 to 6, wherein the hydroxyalkylcellulose comprises about 2 parts by volume hydroxyethylcellulose and the alkylene glycol comprises about 1 part by volume propylene glycol, and including bicarbonate of soda in an amount of about 1/4 part by volume.

12. A composite thermal reservoir as defined in any one of claims 1 to 6, wherein the hydroxyalkylcellulose comprises about 1 part by volume hydroxyethylcellulose, the alkylene glycol comprises about 3/4 part by volume propylene glycol, and including bicarbonate of soda in an amount of about 1/4 part by volume, and a blowing agent in an amount of about 1/26 part by volume.

13. A composite thermal reservoir as defined in claim 1, including a liquefying agent.

14. A composite thermal reservoir produced by mixing the formulation of claim 13 with an unconsolidated volume of textile fibres, and thereafter spinning the mixture into an elongated thread.

15. A composite thermal reservoir padding material as defined in either claims 13 or 14, wherein the liquefying agent is 1,1'azodicarbonamide.

16. A composite thermal reservoir substantially as hereinbefore described in any one of Examples 1 to 14 or in connection with any one of Figures 5 to 8.

17. A garment comprising a composite thermal reservoir as claimed in any one of claims 1 to 16.

18. A method of making a composite thermal reservoir comprising admixing the hydroxyalkylcellulose and the alkylene glycol components optionally together with bicarbonate of soda, a blowing agent and/or a liquefying agent as set out in any of claims 1 and 7 to 16, securing the mixture against a fabric and optionally curing the mixture at an elevated temperature either before or after said securing step.