CA2289971A1 - A mixture for use in the manufacture of a thermal pack and a thermal pack per se - Google Patents
A mixture for use in the manufacture of a thermal pack and a thermal pack per se Download PDFInfo
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- CA2289971A1 CA2289971A1 CA 2289971 CA2289971A CA2289971A1 CA 2289971 A1 CA2289971 A1 CA 2289971A1 CA 2289971 CA2289971 CA 2289971 CA 2289971 A CA2289971 A CA 2289971A CA 2289971 A1 CA2289971 A1 CA 2289971A1
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- stearic acid
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Abstract
There is disclosed a mixture for use in the manufacture of a thermal pack which mixture comprises a first or phase change material and a second material having a relatively high heat capacity. The first material and the second material have characteristics for enabling them to form a solution. Preferably, the first material is searic acid and the second material is rapeseed oil. The first and second material are preferably present in a ration in the range 1:1-1:4, most preferably 3:7.
Description
A MIXTURE FOR USE IN THE MANUFACTURE
OF A THERMAL PACK AND A THERMAL PACK PER SE
This invention relates to a thermal pack.
In particular, the invention is concerned with the provision of a microwave powered personal comfort aid which can be used for relaxation, to provide relief for arthritic or rheumatic pains, for sport injuries, lumbar pains, menstrual pains, etc. In the context of this invention, a thermal pack in general terms is a device such as a hot water bottle, hand held warmer or a cool pack. In particular, it relates to a 1 o thermal pack of the type which is provided with heat energy and subsequently releases that energy as it cools to ambient temperature.
Most particularly, it relates to a heat pack which can receive heat energy by means of microwave activity.
Conventional microwave hot-packs utilise either simple heat in the form of water, thickened water or glycerine or more sophisticated systems using thermo-chemical or phase change systems.
Simple heat systems utilise materials with a high specific heat (>4 J/gm/°C). This type of system is restricted by the fact that whilst water is one of the highest specific heat materials (4.2J/g/°C) it can only 2 0 offer 63 J/g of energy in the ideal comfort range of 45°C to 60°C.
The more sophisticated systems can exceed this figure significantly. Phase change materials (PCM) such as salt hydrates, waxes or fatty acids can exceed this figure by over 200%. Whilst these materials are excellent candidates for heat storage they do suffer from a significant drawback in that as they cool they solidify. This inevitably results in the material agglomerating on one side of the container with parts of the material being over 20mm thick whilst other areas would be less than 5mm thick. This causes subsequent microwave heating problems as the thick section heats slowly compared with the thin sections. This is 3 o compounded by the fact that the solid PCM are, by their nature, significantly less microwave active than their liquid counterparts. This results in very rapid heating of the thin areas which will cause the device to fail due to overheating of the encapsulant in which the material is contained. In addition, the unfriendly 'feel' of such a device in its cold state is not appealing to the consumer.
There are a number of known heat packs of the type having material which is suitable for heating using microwave activity. They generally fall into one of four types:-a) natural material - this consists of a natural material such as corn, to wheat, nuts, housed in a encapsulant which can be heated in a microwave. The problem with this type is that its heat retention characteristics are poor as it stays warm for only about fifteen minutes. In addition, the nature of the material is such as to give off an odour which, for most people, is unacceptable.
b) Dessicant - A dessicant is used instead of natural material. This overcomes the odour problem, but does not overcome the heat retention problem.
c) Gels - This is the most popular and consists of bag containing a mixture of water and a thickening agent added (normally a super 2 o absorbent polymer). As water has one of the highest specific heat capacities (4.2 J/g/°C), this type of product has excellent heat retention characteristics and will stay warm for up to two hours. The problem is that to achieve a sufficiently large heat capacity of say 200J, it is necessary to heat the mixture to approximately 80°C. This is very close to the boiling point of water and water has an extremely high vapour pressure which under certain circumstances could rupture the encapsulant. When this is coupled with the fact that the heat source has a propensity to be very uneven and the thickening agent causes the gel to have a very poor thermal conductivity (due to 3 o the fact that the liquid cannot generate convective currents), this product becomes very unsafe and indeed could explode. This leads to a very complicated and unfriendly method of use. For example, it is necessary to heat the product for thirty seconds; invert; and heat for a further thirty seconds. If not sufficiently hot, inversion is again required followed by a ten second period of heating after which, the product is again inverted and heated for a further ten seconds and so on. It can take up to four minutes to heat the pack to 80°C - a total of twenty inversions.
d) Phase change materials. A wax-like material is housed in an encapsulant. The wax-like material liquefies when heated and will 1 o therefore store significant amount of heat during the phase change from the solid state to the liquid state. The problem is that the wax-like material solidifies on cooling into a hard lumpy material which is not acceptable to the user. Thus, the wax-like material can accumulate at one end of the encapsulant and reheat unevenly with thin areas of the wax material superheating and causing burning. The heat capacity of this type is only about 60% of the heat capacity of water gel type. However, a significant advantage of this type is that substantially all of its heat is outputted at 60°C.
It is an object of the present invention to overcome these 2 o problems.
The invention overcomes these problems by providing a mixture comprising a PCM by combining the PCM and a lubricator or plasticiser. Ideally this lubricator should be a polar liquid which is miscible with the PCM and should have a high specific heat and good thermal conductivity. This will allow the heat source to be properly distributed throughout the PCM.
The invention, therefore, provides a mixture for use in the manufacture of a thermal pack which mixture comprises a first or phase change material and a second material having a relatively high heat 3 o capacity and wherein the first material and the second material have characteristics for enabling them to form a solution.
OF A THERMAL PACK AND A THERMAL PACK PER SE
This invention relates to a thermal pack.
In particular, the invention is concerned with the provision of a microwave powered personal comfort aid which can be used for relaxation, to provide relief for arthritic or rheumatic pains, for sport injuries, lumbar pains, menstrual pains, etc. In the context of this invention, a thermal pack in general terms is a device such as a hot water bottle, hand held warmer or a cool pack. In particular, it relates to a 1 o thermal pack of the type which is provided with heat energy and subsequently releases that energy as it cools to ambient temperature.
Most particularly, it relates to a heat pack which can receive heat energy by means of microwave activity.
Conventional microwave hot-packs utilise either simple heat in the form of water, thickened water or glycerine or more sophisticated systems using thermo-chemical or phase change systems.
Simple heat systems utilise materials with a high specific heat (>4 J/gm/°C). This type of system is restricted by the fact that whilst water is one of the highest specific heat materials (4.2J/g/°C) it can only 2 0 offer 63 J/g of energy in the ideal comfort range of 45°C to 60°C.
The more sophisticated systems can exceed this figure significantly. Phase change materials (PCM) such as salt hydrates, waxes or fatty acids can exceed this figure by over 200%. Whilst these materials are excellent candidates for heat storage they do suffer from a significant drawback in that as they cool they solidify. This inevitably results in the material agglomerating on one side of the container with parts of the material being over 20mm thick whilst other areas would be less than 5mm thick. This causes subsequent microwave heating problems as the thick section heats slowly compared with the thin sections. This is 3 o compounded by the fact that the solid PCM are, by their nature, significantly less microwave active than their liquid counterparts. This results in very rapid heating of the thin areas which will cause the device to fail due to overheating of the encapsulant in which the material is contained. In addition, the unfriendly 'feel' of such a device in its cold state is not appealing to the consumer.
There are a number of known heat packs of the type having material which is suitable for heating using microwave activity. They generally fall into one of four types:-a) natural material - this consists of a natural material such as corn, to wheat, nuts, housed in a encapsulant which can be heated in a microwave. The problem with this type is that its heat retention characteristics are poor as it stays warm for only about fifteen minutes. In addition, the nature of the material is such as to give off an odour which, for most people, is unacceptable.
b) Dessicant - A dessicant is used instead of natural material. This overcomes the odour problem, but does not overcome the heat retention problem.
c) Gels - This is the most popular and consists of bag containing a mixture of water and a thickening agent added (normally a super 2 o absorbent polymer). As water has one of the highest specific heat capacities (4.2 J/g/°C), this type of product has excellent heat retention characteristics and will stay warm for up to two hours. The problem is that to achieve a sufficiently large heat capacity of say 200J, it is necessary to heat the mixture to approximately 80°C. This is very close to the boiling point of water and water has an extremely high vapour pressure which under certain circumstances could rupture the encapsulant. When this is coupled with the fact that the heat source has a propensity to be very uneven and the thickening agent causes the gel to have a very poor thermal conductivity (due to 3 o the fact that the liquid cannot generate convective currents), this product becomes very unsafe and indeed could explode. This leads to a very complicated and unfriendly method of use. For example, it is necessary to heat the product for thirty seconds; invert; and heat for a further thirty seconds. If not sufficiently hot, inversion is again required followed by a ten second period of heating after which, the product is again inverted and heated for a further ten seconds and so on. It can take up to four minutes to heat the pack to 80°C - a total of twenty inversions.
d) Phase change materials. A wax-like material is housed in an encapsulant. The wax-like material liquefies when heated and will 1 o therefore store significant amount of heat during the phase change from the solid state to the liquid state. The problem is that the wax-like material solidifies on cooling into a hard lumpy material which is not acceptable to the user. Thus, the wax-like material can accumulate at one end of the encapsulant and reheat unevenly with thin areas of the wax material superheating and causing burning. The heat capacity of this type is only about 60% of the heat capacity of water gel type. However, a significant advantage of this type is that substantially all of its heat is outputted at 60°C.
It is an object of the present invention to overcome these 2 o problems.
The invention overcomes these problems by providing a mixture comprising a PCM by combining the PCM and a lubricator or plasticiser. Ideally this lubricator should be a polar liquid which is miscible with the PCM and should have a high specific heat and good thermal conductivity. This will allow the heat source to be properly distributed throughout the PCM.
The invention, therefore, provides a mixture for use in the manufacture of a thermal pack which mixture comprises a first or phase change material and a second material having a relatively high heat 3 o capacity and wherein the first material and the second material have characteristics for enabling them to form a solution.
Preferably, the first material is a fatty acid. Preferably, the fatty acid comprises C4-C22, optionally C"-C22, most preferably C~8 (stearic acid).
Preferably, the second material comprises a vegetable oil such as sunflower oil, olive oil. Most preferably, the oil is rapeseed oil.
Preferably, the first material and the second material are in an admixture in a ratio of between 1:1-1:4, most preferably, the ratio of the first material to second 3:7.
The invention also relates to a heat pack which comprises to an encapsulant having a mixture according to the invention therein.
Preferably the encapsulant comprises an elastomer. Preferably, the melting point of the elastomer is at least 165°C.
The invention will be understood in greater detail from the following description of a preferred embodiment thereof given by way of example only.
A mixture is provided which comprises a first material and a second material. The first material comprises a phase change material and the second material has a relatively high heat capacity. The materials have characteristics which can form a solution.
2 o Preferably, the first material is a fatty acid having C4-CzZ
carbon atoms. The most preferred range of carbon atoms is C"-C22 with stearic acid (C,$) being the most preferred. The second material is preferably a vegetable oil such as sunflower oil, olive oil, and most preferably rapeseed oil.
The first material and the second material are in solution in a ratio of between - 1:1-2:8 preferably in a ratio of 3:7.
This use of a fatty acid and in particular stearic acid is that the melting point is in the range of between 60°C and 71 °C
which are optimum temperatures for human comfort. The function of the fatty acid is 3 o to absorb a relatively high level of heat at the phase change temperature (in the case of stearic acid - at 71 °C) as this has the ability to contain a relatively high level of energy when in the molten state. This energy is released in the form of heat at a steady temperature of approximately 60°C (following heating to about 80°C) as the material solidifies.
The vegetable oil used is preferably rapeseed oil, preferably refined rapeseed oil which acts as a lubricating oil. This has the following benefits -1. Good chemical stability at elevated temperature.
2. Low smell.
l0 3. It has a high specific heat - 190J/kg.
4. It has a very low vapour pressure.
5. A boiling point greater than 170°C (this must be higher than melting temperature of the encapsulant as this will ensure that no liquid pressure is generated in the bag as the oil is vaporised).
Preferably, the second material comprises a vegetable oil such as sunflower oil, olive oil. Most preferably, the oil is rapeseed oil.
Preferably, the first material and the second material are in an admixture in a ratio of between 1:1-1:4, most preferably, the ratio of the first material to second 3:7.
The invention also relates to a heat pack which comprises to an encapsulant having a mixture according to the invention therein.
Preferably the encapsulant comprises an elastomer. Preferably, the melting point of the elastomer is at least 165°C.
The invention will be understood in greater detail from the following description of a preferred embodiment thereof given by way of example only.
A mixture is provided which comprises a first material and a second material. The first material comprises a phase change material and the second material has a relatively high heat capacity. The materials have characteristics which can form a solution.
2 o Preferably, the first material is a fatty acid having C4-CzZ
carbon atoms. The most preferred range of carbon atoms is C"-C22 with stearic acid (C,$) being the most preferred. The second material is preferably a vegetable oil such as sunflower oil, olive oil, and most preferably rapeseed oil.
The first material and the second material are in solution in a ratio of between - 1:1-2:8 preferably in a ratio of 3:7.
This use of a fatty acid and in particular stearic acid is that the melting point is in the range of between 60°C and 71 °C
which are optimum temperatures for human comfort. The function of the fatty acid is 3 o to absorb a relatively high level of heat at the phase change temperature (in the case of stearic acid - at 71 °C) as this has the ability to contain a relatively high level of energy when in the molten state. This energy is released in the form of heat at a steady temperature of approximately 60°C (following heating to about 80°C) as the material solidifies.
The vegetable oil used is preferably rapeseed oil, preferably refined rapeseed oil which acts as a lubricating oil. This has the following benefits -1. Good chemical stability at elevated temperature.
2. Low smell.
l0 3. It has a high specific heat - 190J/kg.
4. It has a very low vapour pressure.
5. A boiling point greater than 170°C (this must be higher than melting temperature of the encapsulant as this will ensure that no liquid pressure is generated in the bag as the oil is vaporised).
6. Highly microwave active as the solid fatty acid is not.
7. Will go into solution with fatty acid.
8. Is liquid at room temperature.
The combination of stearic acid and rapeseed oil is to be particularly preferred.
2 o Properties of stearic acid 1. Good chemical stability as it is fully unsaturated.
2. Low smell.
3. It has a high heat of fusion of approximately 190J/g.
4. It has a very low vapour pressure.
5. A boiling point greater that 170°C (this must be higher than melting temperature of the encapsulant as this will ensure that no liquid pressure is generated in the bag as the oil is vaporised).
6. Will not stratify in use.
7. Will go into solution with an oil and in particular rapeseed oil.
3 0 8. Undergoes a phase change when cooling between 55°C and 60°C.
This allows for a situation where a significant amount of the vegetable oil acting as a lubricating oil is released from the crystal matrix of the stearic acid during the first 15 minutes of cooling due to normal agitation. This prevents the crystal structure of the fatty acid encapsulating all the oil and negating the plasticising or lubricating influence of the oil.
Preferably according to this invention refined stearic acid is blended with rapeseed oil. Stearic acid has a phase change temperature outside the ideal comfort range of 45°C to 60°C (pure stearic acid melts at 71 °C) but this allows for a situation where a significant amount of the lubricating oil is released from the crystal matrix due to the normal to agitation experienced during the first 15 minutes of use.
This preferred matrix of stearic acid and rapeseed oil is preferably encapsulated in a thermoplastic polyurethane (TPU) bag. The encapsulant is preferably of the type which has the properties of both plastic and rubber (they contain bonds which will break and reform under the influence of heat). This means that an encapsulant which has the elastic properties of rubber and yet can be formed by the process of heat-sealing which has significant cost saving implications. The encapsulant also has a very good consumer friendly feel to it which is highly desirable.
The polyurethane elastomer also has a very high melting point of 165°C
2 o which allows a sufficient safety margin over the maximum recommended operating temperature. The elastic properties of the TPU will allow for the volume change of up to 600% which will afford a significant safety margin in the case of overheat.
A thick or heavy cover material is used to adjust the comfort feel of the pack.
- The following table will serve to illustrate the effectiveness of the use of a fatty acid when compared with other non-fatty acid substance.
_7_ MaterialHeat Stratif- Microwave Reversible Temp.
Storage ication Reactive cryst.
Salt 2 1 1 1 3 Hyd rates Waxes 2 3 1 3 3 Fatty 3 3 3 3 3 Acids Where 1= poor characteristics, 2= fair characteristics and 3= good characteristics. [NOTE: Reversible Cryst. means the ability (or otherwise) of the material to melt and recrystallise easily.]
The vegetable oil is preferably rapeseed oil which has good chemical stability at elevated temperatures.
Rapeseed oil (a) has a low odour;
(b) is relatively high specific heat;
to (c) has a low vapour pressure;
(d) has a high boiling point >170°C;
(e) is microwave reactive;
(f) forms a homogeneous mixture with stearic acid;
(g) is a liquid at room temperature.
The mixture as described above may be manufactured in bulk and then used in the preparation of a thermal pack in accordance with the invention.
Thus, the mixture according to the invention may be encapsulated in any suitable material and sealed therein to form a thermal 2 o pack. Subsequently, in use, the thermal pack may be subjected to microwave activity in a microwave oven until it reaches a temperature of about 80°C subsequent at which it is used as a thermal pack.
_8_ A most preferred encapsulant is an elastomer with a polyurethane elastomer as being the preferred encapsulant. The most preferred encapsulation is polyurethane thermoplastic elastomer (TPE).
The encapsulant should preferably have a melting point of 165°C or greater which allows a sufficient safety margin over the maximum recommended operating temperature. It is important that the melting point of the encapsulant be less than the boiling point of the vegetable oil as this will ensure that no liquid pressure is generated in the encapsulant as the oil is vaporised.
to In the manufacture of a heat pack approximately 850m1 of the mixture according to the invention is placed or poured into the encapsulant and the encapsulant sealed by heat welding. The most preferred mixture of stearic acid and rapeseed oil in a ratio of 3:7 is employed with a polyurethane TPE encapsulant. If desired, an outer cover of, for example, brushed cotton may be used to provide a more user friendly product. The cover should be such as not to constitute a significant thermal barrier.
To use, the pack is placed in a microwave over and, depending on the power output of the oven, is heated at full power for 2 o between 180s and 300s. This will ensure that the starting temperature is around 99°C. Initially, the pack will cool relatively quickly to about 60°C.
However, while the mixture now gives up its heat, the temperature will remain at about 60°C until such time as the stearic acid has solidified. In other words, until such time as the phase change transition of the acid from a liquid to solid state has been completed. The time period of transition will depend on the surrounding temperature. In the case of a pack which is in a bed and covered by bed covers, the time will be in the range of between 3-5 hours.
Thermal packs for carrying on the body or in pockets of 3 o clothing could also be used in a similar fashion for providing heat to the user.
_g_ The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.
The combination of stearic acid and rapeseed oil is to be particularly preferred.
2 o Properties of stearic acid 1. Good chemical stability as it is fully unsaturated.
2. Low smell.
3. It has a high heat of fusion of approximately 190J/g.
4. It has a very low vapour pressure.
5. A boiling point greater that 170°C (this must be higher than melting temperature of the encapsulant as this will ensure that no liquid pressure is generated in the bag as the oil is vaporised).
6. Will not stratify in use.
7. Will go into solution with an oil and in particular rapeseed oil.
3 0 8. Undergoes a phase change when cooling between 55°C and 60°C.
This allows for a situation where a significant amount of the vegetable oil acting as a lubricating oil is released from the crystal matrix of the stearic acid during the first 15 minutes of cooling due to normal agitation. This prevents the crystal structure of the fatty acid encapsulating all the oil and negating the plasticising or lubricating influence of the oil.
Preferably according to this invention refined stearic acid is blended with rapeseed oil. Stearic acid has a phase change temperature outside the ideal comfort range of 45°C to 60°C (pure stearic acid melts at 71 °C) but this allows for a situation where a significant amount of the lubricating oil is released from the crystal matrix due to the normal to agitation experienced during the first 15 minutes of use.
This preferred matrix of stearic acid and rapeseed oil is preferably encapsulated in a thermoplastic polyurethane (TPU) bag. The encapsulant is preferably of the type which has the properties of both plastic and rubber (they contain bonds which will break and reform under the influence of heat). This means that an encapsulant which has the elastic properties of rubber and yet can be formed by the process of heat-sealing which has significant cost saving implications. The encapsulant also has a very good consumer friendly feel to it which is highly desirable.
The polyurethane elastomer also has a very high melting point of 165°C
2 o which allows a sufficient safety margin over the maximum recommended operating temperature. The elastic properties of the TPU will allow for the volume change of up to 600% which will afford a significant safety margin in the case of overheat.
A thick or heavy cover material is used to adjust the comfort feel of the pack.
- The following table will serve to illustrate the effectiveness of the use of a fatty acid when compared with other non-fatty acid substance.
_7_ MaterialHeat Stratif- Microwave Reversible Temp.
Storage ication Reactive cryst.
Salt 2 1 1 1 3 Hyd rates Waxes 2 3 1 3 3 Fatty 3 3 3 3 3 Acids Where 1= poor characteristics, 2= fair characteristics and 3= good characteristics. [NOTE: Reversible Cryst. means the ability (or otherwise) of the material to melt and recrystallise easily.]
The vegetable oil is preferably rapeseed oil which has good chemical stability at elevated temperatures.
Rapeseed oil (a) has a low odour;
(b) is relatively high specific heat;
to (c) has a low vapour pressure;
(d) has a high boiling point >170°C;
(e) is microwave reactive;
(f) forms a homogeneous mixture with stearic acid;
(g) is a liquid at room temperature.
The mixture as described above may be manufactured in bulk and then used in the preparation of a thermal pack in accordance with the invention.
Thus, the mixture according to the invention may be encapsulated in any suitable material and sealed therein to form a thermal 2 o pack. Subsequently, in use, the thermal pack may be subjected to microwave activity in a microwave oven until it reaches a temperature of about 80°C subsequent at which it is used as a thermal pack.
_8_ A most preferred encapsulant is an elastomer with a polyurethane elastomer as being the preferred encapsulant. The most preferred encapsulation is polyurethane thermoplastic elastomer (TPE).
The encapsulant should preferably have a melting point of 165°C or greater which allows a sufficient safety margin over the maximum recommended operating temperature. It is important that the melting point of the encapsulant be less than the boiling point of the vegetable oil as this will ensure that no liquid pressure is generated in the encapsulant as the oil is vaporised.
to In the manufacture of a heat pack approximately 850m1 of the mixture according to the invention is placed or poured into the encapsulant and the encapsulant sealed by heat welding. The most preferred mixture of stearic acid and rapeseed oil in a ratio of 3:7 is employed with a polyurethane TPE encapsulant. If desired, an outer cover of, for example, brushed cotton may be used to provide a more user friendly product. The cover should be such as not to constitute a significant thermal barrier.
To use, the pack is placed in a microwave over and, depending on the power output of the oven, is heated at full power for 2 o between 180s and 300s. This will ensure that the starting temperature is around 99°C. Initially, the pack will cool relatively quickly to about 60°C.
However, while the mixture now gives up its heat, the temperature will remain at about 60°C until such time as the stearic acid has solidified. In other words, until such time as the phase change transition of the acid from a liquid to solid state has been completed. The time period of transition will depend on the surrounding temperature. In the case of a pack which is in a bed and covered by bed covers, the time will be in the range of between 3-5 hours.
Thermal packs for carrying on the body or in pockets of 3 o clothing could also be used in a similar fashion for providing heat to the user.
_g_ The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.
Claims (18)
1. A mixture for use in the manufacture of a thermal pack which mixture comprises a first or phase change material and a second material having a relatively high heat capacity and wherein the first material and the second material have characteristics for enabling them to form a solution.
2. A mixture as claimed in Claim 1 wherein the first material is a fatty acid.
3. A mixture as claimed in Claim 2 wherein the fatty acid comprises C4-C22, optionally C11-C22, most preferably C18 (stearic acid).
4. A mixture as claimed in Claim 2 wherein the fatty acid comprises C4-C22.
5. A mixture as claimed in Claim 2 wherein the fatty acid comprises C11-C22.
6. A mixture as claimed in Claim 2 wherein the fatty acid is C18 (stearic acid).
7. A mixture as claimed in any of Claims 1-6 wherein the second material comprises a vegetable oil.
8. A mixture as claimed in Claim 7 wherein the oil is sunflower oil.
9. A mixture as claimed in Claim 7 wherein the oil is olive oil.
10. A mixture as claimed in Claim 7 wherein the oil is rapeseed oil.
11. A mixture as claimed in any of Claims 1-10 wherein the first material and the second material are in an admixture in a ratio of between 1:1-1:4, most preferably, the ratio of the first material to the second material is 3:7.
12. A mixture for use in the manufacture of a thermal pack which mixture comprises stearic acid and rapeseed oil.
13. A mixture as claimed in Claim 12 wherein the ratio of stearic acid to rapeseed oil is in the range 1:1-1:4.
14. A mixture as claimed in Claim 12 wherein the ratio of stearic acid to rapeseed oil is 3:7.
15. A heat pack which comprises an encapsulant having a mixture as claimed in any of Claims 1-14.
16. A heat pack as claimed in Claim 15 wherein the encapsulant comprises an elastomer.
17. A heat pack as claimed in Claim 16 wherein the melting point of the elastomer is at least 165°C.
18. A heat pack as claimed in Claim 16 wherein the elastomer is a polyurethane thermoplastic elastomer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IES980951 | 1998-11-17 | ||
| IE980951 | 1998-11-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2289971A1 true CA2289971A1 (en) | 2000-05-17 |
Family
ID=31503910
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2289971 Abandoned CA2289971A1 (en) | 1998-11-17 | 1999-11-17 | A mixture for use in the manufacture of a thermal pack and a thermal pack per se |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2289971A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017005536A1 (en) | 2015-07-03 | 2017-01-12 | Beiersdorf Ag | Heat pads comprising spiral heat cells |
| DE102015212496A1 (en) | 2015-07-03 | 2017-02-09 | Beiersdorf Ag | Heat pads with annular heat cells |
-
1999
- 1999-11-17 CA CA 2289971 patent/CA2289971A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017005536A1 (en) | 2015-07-03 | 2017-01-12 | Beiersdorf Ag | Heat pads comprising spiral heat cells |
| DE102015212494A1 (en) | 2015-07-03 | 2017-02-09 | Beiersdorf Ag | Heat pads with spiral heat cells |
| DE102015212496A1 (en) | 2015-07-03 | 2017-02-09 | Beiersdorf Ag | Heat pads with annular heat cells |
| EP3733138A1 (en) | 2015-07-03 | 2020-11-04 | Beiersdorf AG | Heat pads with helical heat cells |
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