WO2001001827A1

WO2001001827A1 - Heat retaining material and articles made therefrom

Info

Publication number: WO2001001827A1
Application number: PCT/AU2000/000812
Authority: WO
Inventors: Milton Karan; Peter Fryers
Original assignee: Fmj International Marketing Pty Ltd
Priority date: 1999-07-05
Filing date: 2000-07-05
Publication date: 2001-01-11
Also published as: AUPQ142199A0

Abstract

A bed sheet formed from a fabric having a flexible polymeric coating on a surface thereof, the polymeric coating being capable of retaining body heat for generated from that part of the body in close proximity to the polymeric polymeric coating. Preferably the polymeric coating is a crushed polymer foam and includes a particulate magnesium silicate.

Description

Heat retaining material and articles made therefrom

Technical Field

The present invention relates to a heat retaining material. The invention is particularly concerned with a material that is capable of retaining body heat and to articles made at least in part from this material.

Background

A particular context in which there may be a need to provide a source of heat to an individual is during sleep. An old means for warming the occupant of a bed is the hot water bottle. Hot bottles are of limited effectiveness as they only provide localised heating for a relatively short period. Moreover, they pose the risk of burning the occupant of the bed if the bottle is filled with very hot water and can cause scalding in the event of leakage. These days, electric blankets are more commonly used as a means foiwarming the bed. Whilst electric blankets do provide a source of heat and thereby make the bed more comfortable to the occupant, there are significant disadvantages associated with their use.

First, an electric blanket obviously requires a source of electricity close to the bed. thus placing a limitation on the positioning of the bed in the bedroom. Most significantly, the use of electricity as a source of heat raises safety and health issues. Indeed electric blankets contributed to 116 fires and 42 deaths and injuries in Australia in 1998.

A particular disadvantage of an electric blanket is that it must be carefully maintained throughout its life in order to prevent damage to its heating elements. Such damage can lead to hot spots in the blanket which can cause a fire and/or burn the occupant of the bed. The user must also ensure that the connection between the electrical cord and the blanket does not become damaged as this could lead to electrocution or cause a fire as a result of shorting of the wires going into the blanket. Moreover, the options for cleaning an electric blanket are very limited because of the need to avoid damage to the heating elements.

Generally, manufacturer's use instructions for electric blankets indicate that the blanket is only to be used to heat the bed prior to it being occupied and that the blanket is to be turned off before the person goes to bed. This is to avoid the risk of exposing the occupant to excessive heat during sleeping, or electrocution, burning and/or fire in the event of the blanket misfunctioning or being accidentally exposed to liquids through spillage or incontinence. Indeed people suffering from incontinence are reluctant to use an electric blanket because of the risks involved. Additionally, in operation, the elements of an electric blanket produce an electromagnetic field in close proximity to the body. Such radiation may pose a health risk.

Therefore, there remains a need for means that can provide a source of heat but which avoids, or mitigates at least in part, one or more of the disadvantages of the prior art as discussed above.

Disclosure of Invention

In a first aspect, the present invention provides a heat retaining material, the material including a substrate having a polymeric coating on a surface thereof, wherein the polymeric coating is capable of retaining body heat generated by a human or animal in contact with the material.

The heat retaining material of the present invention may be rigid, semirigid or flexible. Preferably the heat retaining material of the invention is a flexible sheet.

The substrate of the heat retaining material of the invention may be a fabric. The fabric may be a natural, synthetic or semi-synthetic fabric, for example, a cotton or polycotton fabric. A particularly preferred substrate is a polyester/cotton Percale. Preferably the polymeric coating material is a foamed polymeric material. Particularly preferred is a crushed foam coating. Crushing of the foam may be achieved by any suitable method, for example, by the use of crushing forces which may also be used to force the particles through the fabric. The polymeric coating of the heat retaining material may be any suitable polymer, for example, a thermoplastic polymer such as an acrylic polymer, or a combination of polymers. The polymer may be a homopolymer or a copolymer. Preferably the polymeric coating is 100% acrylic polymer, however other suitable polymers may be used, for example, a polyurethane. The acrylic polymer may be a polyacrylate. Preferably the polymeric coating is a foamed acrylic polymer. The heat retaining capacity of the polymeric coating may be achieved by means of a heat retaining material incorporated in the polymeric coating. The heat retaining material may be an inorganic mineral. Preferably the mineral has a high specific heat. Preferably the heat retaining material is particulate having a particle size less that about 10 micron. Preferably the particle size is less that about 1 micron. A particle size of about 0.1 micron is particularly suitable. The inorganic material may having a high specific heat, for example, the inorganic mineral may be a silicate. The inorganic material is preferably a magnesium silicate. The inorganic material may be present in an amount of about 5 to 40%

(preferably averaging about 20%) of the polymer coating. The actual loading of the inorganic material used may be chosen so as to achieve the desired degree heat retention.

The polymeric coating may be formed by coating, impregnation or lamination. Preferably the polymeric coating is formed by extruding the polymer containing a foaming agent onto the substrate. The foaming agent may be selected from any suitable foaming agent. An example of a suitable foaming agent is. ammonium stearate onto a surface of the substrate. Part of the extruded coating may be scraped off to achieve the desired coating thickness. Preferably the thickness of the coating is less than about 1mm.

More preferably the thickness of the coating is less that about 0.5mm. Most preferably the thickness of the coating is_ up to about 0.3mm. Thereafter the coaled substrate may be heated to form the foamed polymeric coating. The coating weight may be in the range of about 25% to 40% of the material. In a preferred aspect of the heat retaining material of the invention, the heat retaining material of the invention includes a further coating layer over the foam polymeric coating layer. Preferably this further coating is a cured silicone polymer. Silicone has the advantage of providing better handle to the coated material and "locks" or binds the fabric together. It has the further advantage of reducing any stickiness of the coated material.

In a further aspect the present invention is directed to an article formed al least in part from a heat retaining material in accordance with the present invention. The article may be any article that is normally used in close contact with the body and in which there is a need to provide a source of heat to the body of the user. The article may be an article of apparel, clothing, underclothing, headgear, gloves or footwear. The article may be a sleeping bag liner or sleeping bag or the like. The article may be a household textile or "soft-furnishing". The article may be a bedding accessory, such as bed linen, for example, flat sheets, fitted sheets, pillowcases, bed covers, quilt covers, blankets, underblankets, comforters, mattress protectors, cushions and the like.

The article may be an article used in relation to animals including pets. Examples of these articles include cushions, mats and throw overs for horses and pets.

The article an outdoor article, for example that used for camping. Examples of such articles include sleeping bags, gloves, blankets and the like.

Other applications include the craft market in which case the heat retaining material in accordance with the present invention may be purchased by the metre.

As mentioned above, the article may a piece of clothing or underclothing consisting of or including the heat retaining material in accordance with the present invention. The article of clothing may be, for example, a shirt, jacket, coat, blouse, pant or jumper, cardigan, vest or sweater. The material may be used as a lining in varies type outer wear, for example, leather outer wear incorporating sheeting material in accordance with the invention.

The present invention will now be described with particular reference lo use of the material of the invention in bedding, however, it will be readily by the reader that the material of the invention has wide application in the manufacture of other articles. In one preferred aspect, the present invention provides a bed sheet, wherein the bed sheet is formed from a fabric having a flexible polymeric coating on a surface thereof, the polymeric coating being capable of retaining body heat generated from that part of the body in close proximity to the sheet. In a further preferred aspect, the present invention provides a fitted sheet for covering a mattress or the like, the fitted sheet including a top panel for overlying the top surface of the mattress and means associated with the top panel for holding the panel in place on the mattress and wherein the top panel has a flexible polymeric coating on a surface thereof, the polymeric coating being capable of retaining body heat generated by a human or animal lying on the panel. The sheet and fitted sheet of the present invention are capable of constantly maintaining the body heat generated by the occupant of the bed thereby keeping the occupant warm.

Preferably the fitted sheet of the invention has a top panel which overlies the mattress and two side and two end panels which respectively overly the sides and ends of the mattress and thereby provide the means for holding the top panel to the surface of the mattress. More preferably, the fitted sheet includes a top panel and side and end panels, the side and end panels each also having a heat retaining polymeric coating on a surface thereof. II is lo be understood however that the invention also extends to fitted sheets which have other means for holding the top panel to the mattress top surface, for example elastic loops or the like located at the ends and/or sides of the panel.

The top panel of the fitted sheet may be formed from any material that is suitable for use as a base fabric for a bed sheet, for example, a natural and/or synthetic fabric formed from cotton or a polycotton. A particularly preferred base fabric is a polyester/cotton Percale.

The polymer coating of the top panel may be an acrylic polymer as described above. Preferably the polymeric coating is a foamed acrylic polymer. The means for retaining body heat may be a material combined with the polymeric coating. The heat retaining material may be an inorganic mineral.

In a particularly preferred aspect, the present invention provides a fitted sheet having a top panel and optionally one or more side and/or edge panels, wherein at least the top panel is formed from a fabric coated with a foamed acrylic polymer containing an inorganic heat absorbing material.

In yet a further preferred aspect of the present invention, at least the top panel of the fitted sheet has second coating layer over the foam polymeric coating layer. Preferably this further coating is a cured silicone polymer. Silicone has the advantage of waterproofing the panel and negates the need for a mattress protector.

The fitted sheet of the present invention eliminates the need for an electric blanket or any other mechanical warming device. Because the fitted sheet does not rely on the use of electrical wires as the means for heating, it eliminates the possibility of heat rashes, skin burn, harmful electromagnetic fields and electrocution which may be associated with the use of electric blankets. Moreover, sleeping on the fitted sheet in accordance with the present invention is similar to sleeping on a conventional fitted sheet, but without the uncomfortable feeling of wire under the body which attends the use of an electric blanket. Furthermore, unlike an electric blanket, there is no need to worry about whether or not the electric blanket has been turned off prior to going to bed. Also, unlike an electric blanket, the fitted sheet of the present invention is fully washable ensuring a long usage life.

The fitted sheet of the present invention is particularly useful in facilities provided for those persons needing constant supervision and care, such as nursing homes and hostels. Such facilities are generally reluctant to use electric blankets because of the safety risk to persons under their care.

Modes for carrying out the invention In order that the invention may be more readily understood, we provide the following non-limiting embodiments of a heat retaining material in accordance with the present invention.

Brief Description of Drawings Figure 1 is a graph showing the temperature variation over time for heat retaining sheeting material in accordance with the present invention (-♦- ) and a standard sheet (-D-] Example 1

Samples of coated fabric in accordance with the present invention were formed from a base cloth of either 100% cotton fabric or 50% polyester

50 % cotton Percale having 110x90 threads per square inch. In each case, a crushed foam coating based on a durable 100% acrylic polymer compounded with an inorganic mineral having a high specific heat was formed on a surface of the base cloth. The acrylic coating was formed by extruding a layer of the acrylic polymer containing the inorganic material and a foaming agent onto the base material followed by two passes through an oven to cure and foam the acrylic polymer. A further coating of a silicone polymer was provided on the foamed acrylic layer and then given a single pass through a curing oven. The results given in Tables 1 and 2 below provide a comparison between the heat retention properties of uncoated fabric with a fabric coated in accordance with the present invention. The results in Table 1 are based on a 100% cotton base fabric and Table 2 shows the results for a 50/50 polyester/cotton Percale base fabric. The results given in the Tables show that both the coated cotton and coated cotton/polyester base fabrics retained heat for a significant period, demonstrating their ability to provide a source of bed heating.

The results given in the two tables further show that use of a polyester/cotton base fabric results in a greater heat retention capability of the coated polyester/cotton fabric than coated 100% cotton.

TABLE 1

TABLE 2

Example 2 A queen-size ensemble bed was made up with a woollen underlay, fitted bottom sheet, top sheet, blanket and continental quilt. A standard K- type thermocouple was placed between the t-shirt worn by the female subject and the bottom sheet. Temperatures were then recorded at one-minute intervals. In changing from a standard sheet to the bottom sheet formed from the heat retaining sheet in accordance with the present invention, the subject lay on a different part of the bed to avoid the complication of heat build-up and hence false readings. The ambient room temperature was around 22°C. The results are plotted in the Figure 1. They clearly show that for the tests conducted on the sheet in accordance with the embodiment of the present invention warmed up quicker and to a higher temperature than a standard sheet. After just five minutes the sheet of the invention was 1.2°C warmer, and remained around 1°C warmer for the duration of the test.

These findings suggest that the sheet in accordance with the invention reduced heat loss through the mattress by 25%. Given that a person will also lose heat through the top covers, it seems reasonable to expect that around 10% more of the body's heat is conserved by the sheet in accordance with the invention than a standard fitted sheet.

These tests were conducted in a room with an ambient temperature of 22°C. If the room were cooler, say 12°C, as most bedrooms are of a night, then a larger difference is to be expected in temperature (more than 1.5°C) and a slightly larger reduction in heat loss of 27% through the mattress.

Discussion Two points emerge from these trials which are most significant. First, the rapid attainment of a comfortable body temperature and secondly, the achievement and maintenance of a body temperature a full degree higher than that of the control test which used normal bedding.

Until a comfortable body temperature has been reached in bed, the body remains tense and there is a higher demand on the metabolic process to achieve and then maintain an ideal body temperature. A higher metabolic rate is of course a higher expenditure of energy and this at the very time that the body is supposed to be relaxing, winding down the metabolism and preparing to sleep and recuperate.

The significantly faster rate of achieving a comfortable body temperature using a sheet in accordance with the present invention is a very attractive benefit. It allows the person to "unwind" or relax in bed more quickly and the person can therefore more readily enter into a relaxed sleep state.

The second benefit lies in the significance of one degree of temperature when referring to body heat. Normal body temperature is around 37°C. Just two degrees below this, or 35°C, is considered to be the start of hypothermia and just two degrees above normal, or 39"C is the point of onset of fever. To stay within these very narrow margins, the body has quite sophisticated mechanisms to monitor and maintain ideal body temperature.

If body temperature is too high, adjustment is affected by heat loss through the skin. Blood capillaries near the skin surface will dilate, bringing more blood to the skin surface to facilitate heat loss. Also, the sweat glands will produce perspiration that cools the body as it evaporates from the skin, in exactly the same manner as an evaporative air conditioner cools the air passing through it. If body temperature is to low, then the rate of metabolism of glucose and oxygen into heat and energy within the cells of the body must increase in order to restore ideal body temperature. Both of these processes place a demand on the energy resources of the body. As the sheeting does not add any heat to the body, but functions by assisting the body to restore and maintain its natural temperature by reducing the rate of heat loss, the sheeting cannot overheat the body. The achievement of a body temperature a full degree higher than that of the control test using normal bedding, shows that the sheeting allows the body to rest at a more ideal temperature as determined by the body's own mechanisms. The control test suggests that normal bedding does not allow the body to fully reach its ideal temperature at rest and it follows that the body would therefore use more energy throughout the sleep period, trying to maintain temperature against the greater level of heat loss evident with normal bedding. The failure of the body to fully reach its ideal temperature whilst sleeping in normal bedding reflects the body's reduced ability to maintain body temperature whilst inactive, even at a higher metabolic rate.

Thus, the ability of sheeting in accordance with the embodiment of the present invention to bring about the achievement and maintenance of a body temperature a full degree higher than that of the control test using normal bedding, results in a more comfortable rest together with the conservation of energy resources. This promises a more satisfying, healthy and refreshing sleep.

Comparing the sheeting of the present invention with a conventional electric blanket the latter heats the bed and therefore heats the body in it.

This added heat invariably overheats the body and places a demand on the body's resources as it works to restore ideal temperature once more. This is especially a problem if the person leaves the electric blanket switched on all night (a very unwise practice). If the blanket is switched off as the person retires, there will be a period of time where the body experiences too much heat and must work to overcome this. Then there will be a short period where the temperature in the bed is fairly ideal, followed by the rest of the night where the heat loss, in what is now effectively a normal bed with no electric blanket running, will require the body to raise its rate of metabolism once more, to try to maintain body heat. The process involved with the sheeting of the present invention is markedly different. As the sheeting adds no heat to the bed, there will be a short period where the bed is cold as the person first gets into it. However, the rapid achievement of ideal body temperature with sheeting will minimise this. There then follows a full night of minimal heat loss and therefore minimal demand on the body's resources to maintain an ideal body temperature. This is a far more desirable situation.

From what has been described above, it will be evident to the reader that the sheeting in accordance with one aspect of the present invention have applications beyond the home or domestic use. The advantages make it suitable for use in nursing homes, hostels and institutions. However, the sheeting offers more than simply extra comfort and improved sleep. It makes a very real contribution in the much more serious field of reducing trauma and even saving human lives. If a person is ill or injured, and especially if the person is in shock, there can be a substantial drop in body temperature.

In an emergency situation, it is imperative that body temperature be restored as close to normal as possible in the shortest possible time. The benefits of sheeting for ambulances, hospitals and other emergency services, including the armed forces, are therefore clear. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A heal retaining material, the material including a substrate having a polymeric coating on a surface thereof, wherein the polymeric coating is capable of retaining body heat generated by a human or animal in contact with the material.

2. A heat retaining material according to claim 1 wherein the polymeric coating includes a heat retaining substance.

3. A heat retaining material according to claim 1 or claim 2 wherein the heat retaining substance is or comprises an inorganic heat absorbing mineral.

4. A heat retaining material according lo claim 3, wherein the inorganic material is in a particulate form.

5. A heat retaining material according to claim 4 wherein the inorganic material is an inorganic silicate.

6. A heat retaining material according to claim 5 wherein the inorganic silicate is magnesium silicate.

7. A heat retaining material according to any one of the previous claims wherein the polymeric coating is a foamed polymeric coating.

8. A heat retaining material according to claim 7 wherein the polymeric coating is a crushed polymeric coating.

9. A heat retaining material according any one of the preceding claims wherein the polymeric coating is comprised of an acrylic polymer.

10. A heat retaining material according to any one of the previous claims including at least one further coating or layer.

11. A heat retaining material according to claim 10 wherein the at least one further coating or layer is formed from a waterproofing substance.

12. A heat retaining material according to claim 11 wherein the waterproofing substance is a silicone polymer.

13. A heat retaining material according to any one of the preceding claims wherein the substrate is in the form of a flexible sheet.

14. A heal retaining material according to any one of the preceding claims wherein the substrate of the heat retaining material of the invention is a natural, synthetic or semi-synthetic fabric.

15. A heat retaining material according to claim 14 wherein the fabric is a cotton or polycotton fabric.

16. A heat retaining material according to claim 15 wherein the fabric is a polyester/cotton Percale.

17. A heat retaining material according to any one of the preceding claims wherein the polymeric coating is on one surface of the material.

18. A heat retaining material according to any one of claim 1 to 16 wherein the material has two sides and the polymeric coating is on both sides.

19. An article consisting of or comprising a heat retaining fabric according to any one of the preceding claims.

20. An article according to claim 19 wherein the article is a bedding accessory.

21. An article according to claim 20 wherein the bedding accessory is selected from the group consisting of a flat sheet, fitted sheet, pillowcase, quilt cover, bed cover, cushion, blanket, underblanket, comforter and mattress protector.

22. An article according to claim 21 which is a bed sheet.

23. An article according to claim 22 wherein the sheet is a fitted sheet.

24. An article according to claim 19 that is an article of clothing, underclothing, headgear or footgear.

25. A bed sheet formed from a fabric having a flexible polymeric coating on a surface thereof, the polymeric coating being capable of retaining body heat for generated from that part of the body in close proximity to the polymeric coating.

26. A bed sheet according lo claim 25 wherein the bed sheet is a fitted sheet.

27. A bed sheet according to claim 26 having a top panel for overlying the top surface of a mattress or the like and means for holding the panel in place on the mattress or the like, and wherein the top panel has a flexible polymeric coating on a surface thereof, the polymeric coating being capable of retaining body heat generated by a human or animal lying on the panel.

28. A bed sheet according to any one of claims 25 to 27 wherein the polymeric coating a heat retaining substance.

29. A bed sheet according to claim 28 wherein the heat retaining substance is or comprises an inorganic heat absorbing mineral.

30. A bed sheet according to claim 29, wherein the inorganic material is in particulate form.

31. A bed sheet according to claim 30 wherein the inorganic material is an inorganic silicate.

32. A bed sheet according to claim 31 wherein the inorganic silicate is magnesium silicate.

33. A bed sheet according to any one of claims 25 to 32 wherein the polymeric coating is a foamed polymer.

34. A bed sheet according to claim 33 wherein the polymeric coating is a crushed foamed polymer.

35. A bed sheet according to claim 33 wherein the polymer is an acrylic polymer.

36. A bed sheet according to any one of claims 25 to 35 further including a waterproofing layer above the polymeric layer.

37. A bed sheet according to claim 36 wherein the waterproofing layer is formed from a silicone.