JP7154742B2 - heating tool - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heating tool such as a disposable body warmer.

Disposable body warmers have been conventionally used as heating tools for warming the body (see, for example, Patent Document 1), and are frequently used because of their excellent portability, safety, convenience, etc., and low cost.

A general disposable body warmer has an exothermic composition that generates heat upon contact with air enclosed in an air-permeable inner bag. By holding the disposable body warmer in hand and rubbing it, the air comes into almost uniform contact with the exothermic composition in the inner bag, causing the exothermic composition to generate heat.

JP-A-5-208031

Such disposable body warmers control the heat generation temperature by adjusting the amount of air that is brought into contact with the exothermic composition. For example, when a synthetic resin film is used as the material of the inner bag, perforations are provided in the synthetic resin film in order to impart breathability to the inner bag. The amount of contacting air is adjusted.

Here, the heat generation temperature of disposable body warmers decreases as the temperature of the environment in which they are used decreases. Therefore, in order to obtain a higher exothermic temperature, it is necessary to increase the air permeability of the inner bag to allow more air to come into contact with the exothermic composition. Therefore, when the size and number of perforations in the inner bag are increased, there is a problem that the exothermic composition inside leaks out from the inner bag. In addition, if the inner bag is made more breathable, even when the disposable body warmer is not in use (for example, when it is just put in a pocket), a large amount of air comes into contact with the heat-generating composition, and the heat-generating composition is greatly dissipated. Since the heat is generated, the heat generation temperature of the disposable body warmer is always high, and there is also the problem that it becomes too hot when used in a relatively high temperature environment such as indoors. As described above, the conventional disposable body warmer has a problem that it cannot be adjusted to a suitable temperature according to the use scene and the use environment.

The present invention has been made with a focus on the above-described problems, and by raising the heat generation temperature when necessary without increasing the air permeability of the inner bag, it is possible to adjust the temperature appropriately according to the usage scene and usage environment. To provide a heating tool capable of

The above object of the present invention is to provide an exothermic composition that generates heat when it comes into contact with air, an inner bag that is air permeable and encloses the exothermic composition, and a space that can contain air inside. and an air absorbing/releasing material that deforms to absorb and/or release air, and the ratio V2/ This is achieved by a heating tool having V1 of 0.11 or more.

In the heating tool configured as described above, the air absorbing/releasing material is preferably a sponge, and more preferably, the sponge is a urethane sponge.

According to the heating tool of the present invention, when the user holds the heating tool in his/her hand and kneads it during use, the air absorbing/releasing material is deformed by the action of the external force applied by the hand and releases the air inside to the outside. and/or draw outside air inside. As a result, more air comes into contact with the exothermic composition, so the heating temperature of the heating tool can be increased without increasing the air permeability of the inner bag. At this time, the ratio V2/V1 of the volume V2 of the space in the air absorbing/releasing material to the volume V1 of the internal space of the inner bag is 0.11 or more, thereby maximizing the calorific value of the exothermic composition. can be as large as Therefore, the heating temperature of the heating tool can be made very high, and even if the temperature of the environment in which the heating tool is used is low, the high heating temperature can provide good heat. Furthermore, since it is not necessary to increase the air permeability of the inner bag, the heating temperature of the heating tool does not rise excessively when the heating tool is not used or when the heating tool is used in a high-temperature environment without being rubbed. Therefore, it is possible to adjust the temperature appropriately according to the use scene and the use environment.

1 is a plan view of a heating tool according to an embodiment of the present invention; FIG. 2 is a cross-sectional view of FIG. 1; FIG. It is an explanatory view showing the use state of the heating tool. 1 is a perspective view of a sponge that is an example of an air absorbing/releasing material; FIG. FIG. 4 is an explanatory diagram showing an example of a method for measuring the volume of a space inside a porous body; FIG. 4 is a cross-sectional view of a heating tool according to another embodiment of the present invention; It is a graph which shows the temperature change of the heating temperature of a heating tool. It is a graph which shows the temperature change of the heating temperature of a heating tool. It is a graph which shows the temperature change of the heating temperature of a heating tool.

Hereinafter, embodiments of a heating tool according to the present invention will be described with reference to the drawings. The heat generating tool 1 includes an exothermic composition 2, an inner bag 3, and an air absorbing/releasing material 4, as shown in FIGS. In the heating tool 1 of this embodiment, an exothermic composition 2 and an air absorbing/releasing material 4 are enclosed in an inner bag 3 . An example of the heating tool 1 is a disposable body warmer, which can be held in the hand and applied to various parts of the body such as limbs, waist, back, abdomen, soles, shoulders, buttocks, etc. to give heat. can. The heating tool 1 is housed in an airtight outer bag (not shown) before use.

The exothermic composition 2 generates heat upon contact with air. Examples of the exothermic composition 2 include oxidizable metals, activated carbon, carbon black, water retention agents (wood flour, vermiculite, diatomaceous earth, perlite, silica gel, alumina, water-absorbent resin, etc.), metal salts (salt, etc.). and water in appropriate amounts, and known compositions conventionally used in disposable body warmers can be used.

The inner bag 3 has a flat bag-like shape with a rectangular front surface and a back surface in plan view, and has an internal space capable of enclosing the exothermic composition 2 therein. In this embodiment, the inner bag 3 is formed by stacking two sheets of a first sheet material 30 and a second sheet material 31 which are rectangular in plan view and form front and back surfaces, and the four side edges are sealed using a known adhesive. It is formed into a bag-like shape by (bonding) or thermal bonding (heat sealing). Alternatively, one sheet material may be folded and overlapped, and the three side edges may be sealed (bonded) with an adhesive or thermally bonded (heat-sealed) to form a bag.

Both sheet members 30 and 31 have flexibility so that the heating tool 1 can be massaged by hand and fitted to the body. At least one of the sheet members 30 and 31, the first sheet member 30, has air permeability.

As the first sheet material 30, it is preferable to use a resin film in consideration of strength, durability against heat generation of the exothermic composition 2, and the like. Although the resin used for the resin film is not particularly limited, it is preferable to use a thermoplastic resin. Examples of thermoplastic resins include polyethylene, polypropylene, polyester, polyamide, polyurethane, polystyrene, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polycarbonate, ethylene-vinyl acetate copolymer, and the like. , polypropylene, and ethylene-vinyl acetate copolymer can be preferably exemplified. These resins may be used alone or in combination of two or more.

A plurality of perforations (not shown) are formed in the resin film used for the first sheet material 30 in order to ensure breathability, and air communicates between the inside and outside of the inner bag 3 through the plurality of perforations. . The perforations may be formed evenly over the entire resin film, or may be densely formed in a portion of the resin film. The size of the perforations is not particularly limited as long as it is large enough to prevent the exothermic composition 2 from leaking to the outside of the inner bag 3, but is preferably 0.1 mm or more and 0.3 mm or less. can. The outer shape and number of perforations are also not particularly limited, and the size, shape, and number of perforations are appropriately set in consideration of the sensible temperature of the heating tool 1 during use according to the air permeability of the inner bag 3 . A conventionally known method can be used as a method for forming perforations in the resin film.

In addition, considering that the first sheet material 30 is good to the touch of the heating tool 1, a woven or nonwoven fabric having air permeability is further used, and the woven or nonwoven fabric is laminated on the resin film. It is preferable to configure by In this case, the resin film is arranged on the inner side facing the exothermic composition 2, and the woven or non-woven fabric is arranged on the outer side.

Breathable woven or non-woven fiber materials include synthetic fibers such as nylon, vinylon, polyester, rayon, acrylic, polyethylene, polypropylene, acetate, polyvinyl chloride, and polybutylene terephthalate, cotton, linen, silk, and paper. and natural fibers, and mixed fibers of synthetic fibers and natural fibers. Among them, from the viewpoint of providing a good feel to the touch, examples of fiber materials include nylon, polyester, polypropylene, and the like, and more preferably nylon and polyester. These fibrous materials may be used alone or in combination of two or more. The basis weight of the woven fabric or non-woven fabric is not particularly limited as long as it can prevent the exothermic composition 2 from leaking out of the inner bag 3, but a preferred example is 20 g/m ² or more and 70 g/m ² or less. can be done.

The other second sheet material 31 can be composed of a single resin film or a laminate obtained by laminating a woven or nonwoven fabric on a resin film, like the first sheet material 30 described above. As the resin used for the resin film and the fibrous material of the woven fabric or non-woven fabric, the same ones as those exemplified for the first sheet material 30 can be preferably exemplified. The resin film forming the second sheet material 31 may or may not have perforations for securing air permeability.

The thicknesses of the first sheet material 30 and the second sheet material 31 are not particularly limited, but the smaller the thickness, the softer the heating tool 1 and the easier it is to fit in the hand. It is preferable that the thickness is about 0.1 mm or more and 2.0 mm or less.

The air absorbing/releasing material 4 has a space in which air can be contained therein, and is deformed to discharge the air in the space to the outside and/or suck in the air from the outside to release the air in the space. It takes air inside. Specifically, the air absorbing/releasing material 4 releases internal air to the outside as it contracts and deforms, and sucks in outside air as it expands and deforms. The air absorbing/releasing material 4 may absorb and release air by repeating compression deformation and expansion deformation each time an external force is applied. It is preferable to try to get back into shape. As a result, once the external force is applied, the contraction deformation (or compression deformation) is performed to release the internal air to the outside (or the external air is sucked in), and then the external force is removed to automatically expand and restore (or contraction and recovery) to suck in outside air (internal air is released to the outside). As the elasticity, it is sufficient that the air absorbing/releasing material 4, which has been deformed by an external force, tries to return to its original shape, and does not necessarily need to have the property of completely returning to its original shape. Moreover, it is preferable that the air absorbing/releasing material 4 further has flexibility so that it can be easily deformed.

As shown in FIG. 3, the heat generating tool 1 configured as described above is deformed (for example, contraction), thereby releasing the air in the air absorbing/releasing material 4 to the outside. The air released from the air absorbing/releasing material 4 is ventilated to the outside of the inner bag 3. At this time, the exothermic composition 2 and the air come into contact with each other. Further, when the user opens the hand holding the heating tool 1, the air absorbing/releasing material 4 is deformed (for example, expands) in an attempt to return to its original shape by removing the external force applied by the hand. of air is ventilated into the inner bag 3 and sucked into the air absorbing/releasing material 4. At this time, the exothermic composition 2 and the air come into contact with each other. When this operation is repeated by rubbing the heating tool 1, a large amount of air comes into contact with the exothermic composition 2 in the inner bag 3, and the exothermic composition 2 effectively generates heat. The exothermic temperature can be greatly increased.

Therefore, it is preferable to increase the amount of air passing through the inner bag 3 in order to bring the exothermic composition 2 into contact with a large amount of air to increase the amount of heat generated. In order to increase the amount of air that passes through the air absorbing/releasing material 4, the relative ratio between the volume V2 of the space in the air absorbing/releasing material 4 and the volume V1 of the internal space of the inner bag 3 The ratio V2/V1) of the volume V2 of the space in the air absorbing/releasing material 4 is an important factor. It has been found that a sufficient amount of air is ventilated through the inner bag 3 to maximize the heating temperature of the heating tool 1 to a very high temperature.

Therefore, in order to allow more air to pass through the inner bag 3 and maximize the calorific value of the exothermic composition 2, in the present invention, an air absorbing/releasing material occupying the volume V1 of the inner space of the inner bag 3 The ratio V2/V1 of the volume V2 of the space inside 4 is set to 0.11 or more.

As the air absorbing/releasing material 4, for example, a porous body can be preferably used. The porous body has a structure having spaces such as small holes, cracks, and voids inside, and air is contained in the spaces, and the air in the spaces is released to the outside as it shrinks and deforms, External air is sucked into the space as it expands and deforms. Since the porous body has elasticity, it can be automatically restored (expanded or shrunk) when the external force is removed, after being deformed (shrinked or expanded) by the application of the external force.

For example, as shown in FIG. 4, a sponge 40 can be preferably used as the elastic porous body. As the sponge 40, synthetic sponge mainly made of synthetic resin materials such as urethane resin and melamine resin, natural sponge mainly made of natural materials such as sea sponge and cellulose, synthetic rubber, and rubber materials such as natural rubber are mainly used. Various sponges can be used, such as a rubber sponge. Among these, it is preferable to use urethane sponge. The urethane sponge is filled with fine pores, is flexible and has high elasticity (restoring property), and can be used at a low cost on the market.

The dimensions of the sponge 40 are particularly such that the ratio V2/V1 of the volume V2 of the space inside the sponge 40 to the volume V1 of the internal space of the inner bag 3 is 0.11 or more and can be enclosed in the inner bag 3. It is not limited. The sponge 40 may be one large sponge having a predetermined volume enclosed in the inner bag 3 as shown in FIG. 4(A), or a plurality of large sponges as shown in FIG. It may be divided into (two in the illustrated example) small sponges and enclosed in the inner bag 3 . In addition, when a plurality of sponges 40 are enclosed in the inner bag 3 , the volume of the space of all the enclosed sponges 40 becomes the volume V2 of the space of the air absorbing/releasing material 4 . Also, the shape of the sponge 40 is not particularly limited, and various shapes such as rectangular parallelepiped, cubic, spherical, ellipsoidal, and columnar can be used.

When a porous body is used as the air absorbing/releasing material 4, the volume V2 of the space in the porous body can be obtained, for example, as shown in FIG. (Fig. 5(A)), the graduated cylinder 11 is turned upside down and fixed in the water tank 10 (Fig. 5(B)). Then, the porous body (for example, the sponge 40) is gently moved to the lower part of the measuring cylinder 11 (FIG. 5(C)), and the porous body (for example, the sponge 40) is compressed. ) is discharged into the graduated cylinder 11, and the amount of air is measured (FIG. 5(D)). By repeating each of the steps (A) to (D) described above five times and obtaining the average of the measured air amounts, the volume V2 of the space in the porous body can be calculated.

The method for measuring the volume V2 of the space inside the porous body is not limited to the method described with reference to FIG. 5, and other methods can also be used. For example, as another measuring method, a beaker filled with water is placed on an electronic balance, a porous body is fixed in the beaker in a state of being suspended in water, and its weight is weighed. In order to make the porous body float in water, if the porous body floats in water, it is made to float by attaching a weight to the porous body and submerging it in water. For example, the porous body can be made to float by supporting it in the water in a suspended state with a hanging tool or the like. Then, by compressing the porous body suspended in water, the weight after the air retained in the porous body is released is measured, and the change in weight before and after compression is measured. From this weight change, the volume V2 of the porous body space can be calculated (1 g=1 cm ³ ).

The air absorbing/releasing material 4 is not necessarily limited to a porous material such as sponge. For example, as the air absorbing/releasing material 4, an elastic hollow body can be used. The hollow body has a space inside and has at least one communication port that communicates the space with the outside. Air is contained in the space, and the air in the space contracts. Due to the deformation, it is released to the outside through the communication port, and due to the expansion and deformation, the external air is sucked into the space. Since the hollow body has elasticity, the hollow body deformed (contracted or expanded) by applying an external force can be automatically restored (expanded or contracted) when the external force is removed. This elastic hollow body can be made of a rubber material or a synthetic resin material.

When a hollow body is used as the air absorbing/releasing material 4, the volume V2 of the space inside the hollow body can be determined, for example, by first measuring the weight of the empty hollow body using an electronic balance. Then, the hollow body is filled with water using a syringe filled with water, and the weight of the hollow body at the time when the water is ejected from the communication port is measured to determine the amount of water filled in the hollow body. Calculate This calculated amount of water can be calculated as the volume V2 of the hollow body (1 g=1 cm ³ ).

The shape of the hollow body is not particularly limited, and various shapes such as bag-like, box-like, cylindrical, bellows-like, and spherical can be used. As for the dimensions of the hollow body, if the ratio V2/V1 of the volume V2 of the space of the air absorbing/releasing material 4 to the volume V1 of the internal space of the inner bag 3 is 0.11 or more and can be enclosed in the inner bag 3. , is not particularly limited. In addition, a plurality of hollow bodies can be enclosed in the inner bag 3, and when a plurality of hollow bodies are enclosed in the inner bag 3, the volume of the space of all enclosed hollow bodies is the same as the volume of the air absorbing/releasing material 4. It becomes the volume V2 of space.

The above-mentioned porous bodies and hollow bodies are normally in a flattened state, expands by the application of an external force to absorb and contain the outside air, and shrinks when the external force is removed. The internal air may be released to the outside.

According to the heat generating tool 1 having the configuration described above, when the user holds the heat generating tool 1 in his/her hand and kneads it during use, the air absorbed/released from the air absorbing/releasing material 4 is absorbed into the exothermic composition 2 in the inner bag 3. The exothermic composition 2 generates heat upon contact. At this time, since the ratio V2/V1 of the volume V2 of the space of the air absorbing/releasing material 4 to the volume V1 of the internal space of the inner bag 3 is 0.11 or more, the calorific value of the exothermic composition 2 is can be maximized, and the heating temperature of the heating tool 1 can be made very high. Therefore, even if the temperature of the environment in which the heating tool 1 is used is low, it is possible to provide good heat due to the high heat generation temperature.

On the other hand, when the heat-generating tool 1 is not used (for example, when it is just put in a pocket) or when the heat-generating tool 1 is used in a high-temperature environment without rubbing, the heat-generating composition 2 is provided with perforations. Since only the ventilated air contacts the inside of the inner bag 3, the heat generation of the exothermic composition 2 is suppressed, the heat generation temperature of the heating tool 1 does not rise greatly, and the heating tool 1 does not reach a high temperature.

In this way, with the heating tool 1 configured as described above, the heat generation temperature can be greatly increased when necessary, and an excessive increase in the heat generation temperature can be suppressed at other times. You can adjust the temperature to your liking.

Furthermore, according to the heating tool 1 configured as described above, the heat generation temperature is increased without increasing the air permeability of the inner bag 3, so the size and number of perforations provided in the synthetic resin film constituting the inner bag 3 can be increased. Therefore, it is possible to prevent the exothermic composition 2 inside the inner bag 3 from leaking out of the inner bag 3.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention.

For example, in the above embodiment, the air absorbing/releasing material 4 is sealed inside the inner bag 3 , but it may be integrated with the inner bag 3 . Specifically, it may be attached to the inner side (exothermic composition 2 side) or the outer side of the breathable first sheet material 30 of the inner bag 3 . Further, as shown in FIG. 6, when the first sheet material 30 is configured by a laminate in which a woven fabric or nonwoven fabric 30A is laminated on a resin film 30B, it is possible to interpose between the woven fabric or nonwoven fabric 30A and the resin film 30B. You may let

In the above-described embodiment, the inner bag 3 has a rectangular shape in a plan view, but it is not limited to a rectangular shape, and various other shapes such as a square shape, a circular shape, an elliptical shape, and a polygonal shape such as a hexagonal shape can be used. can do.

In addition, in the above-described embodiment, only one enclosing space for the exothermic composition 2 is provided in the inner bag 3, but a plurality of enclosing spaces may be partitioned and provided.

Examples of the present invention will be described below. In addition, the present invention is not limited to the following examples.

First, as an example, an exothermic composition containing 53% iron powder, 12% activated carbon, 2.6% vermiculite, 2.5% water-absorbing resin, 1.6% salt and 28.3% water was placed in an inner bag. Perforated nylon non ^- woven fabric/polyethylene resin breathable inner bag ⁽ dimensions: 130 mm x 95 mm ). In addition, a urethane sponge of a predetermined size (“Cut Sponge Hard SR01-4585 (urethane foam”), imported and sold by Kohnan Shoji Co., Ltd.) was placed in an inner bag as an air absorbing/releasing material and sealed to obtain a heating tool. After that, the heating tool was quickly placed in an air-impermeable outer bag.The dimensions (width x length x thickness) of the urethane sponges were 60 mm x 80 mm x 10 mm (Example 1) and 60 mm x 60 mm x 10 mm, respectively. (Example 2) and 60 mm × 40 mm × 10 mm (Example 3) were prepared and housed in separate inner bags to produce three types of heating tools. A heating tool was prepared in the same manner as in Example except that a urethane sponge (width x length x thickness) of 60 mm x 20 mm x 10 mm was accommodated in the inner bag. Similarly, a heating tool of Comparative Example 2 was produced.

Here, the volume V1 of the inner bag is obtained by first preparing an empty inner bag and weighing it using an electronic balance. Then, the upper part of the inner bag is pierced with the needle of a syringe filled with water, water is put into the inner bag, and the inner bag is filled with water. The amount of water filled in the inner bag is calculated by weighing the Since this calculated amount of water was 166.39 g, this amount of water was taken as the volume V1 of the inner bag (1 g=1 cm ³ ).

In each of Examples 1 to 3 and Comparative Example 1, the volume V2 of the space in the sponge (porous body) as the air absorbing/releasing material was 38.4 cm ³ , 28.8 cm ³ and 19.2 cm ³ respectively. , 9.6 cm ³ .

Therefore, in each of Examples 1 to 3 and Comparative Example, the ratio V2/V1 of the volume V2 of the space of the air absorbing/releasing material 4 to the volume V1 of the internal space of the inner bag 3 was 0.23 and 0.23, respectively. 17, 0.11, 0.05.

The heating tools of Examples 1 to 3 and Comparative Examples 1 and 2 were stored in an outer bag and stored for one day in an environment with a temperature of 20° C.±1° C. and a humidity of 55% to 70%. After storage, under the same environment, remove each heating tool from the outer bag, attach the temperature sensor to the surface of the inner bag with tape, and then place the temperature sensor on the other side of the heating tool. The heat generation temperature of the heating tool was measured for 40 minutes while holding the surface in hand and rubbing the heating tool once every 5 seconds. The measurement results are shown in FIG.

In addition, the heating tool of Example 2 was stored in an outer bag in an environment at a temperature of 5° C. for one day. After storage, under the same environment, remove each heating tool from the outer bag, attach the temperature sensor to the surface of the inner bag with tape, and then place the temperature sensor on the other side of the heating tool. The heat generation temperature of the heat generating tool was measured for 50 minutes while holding the surface in hand and rubbing the heat generating tool once every 5 seconds. The measurement results are shown in FIG.

In addition, the heating tool of Example 1 was stored in an outer bag for one day in an environment with a temperature of 20° C.±1° C. and a humidity of 55% to 70%. After storage, under the same environment, the heating tool was taken out from the outer bag, and the temperature sensor was attached to the surface of the inner bag with tape. After rubbing the heating tool, the heating tool was placed on the hand without rubbing for 20 minutes, and then the heating tool was again rubbed for 15 minutes at a pace of once every 5 seconds to lower the heat generation temperature of the heating tool. Measured. The measurement results are shown in FIG.

As is clear from FIG. 7, in Examples 1 to 3 and Comparative Example 1 in which the air absorbing/releasing material is contained in the inner bag, the heating temperature of the heating tool is higher than in Comparative Example 2. 1 to 3, the heat generation temperature of the heating tool is significantly higher than that of Comparative Example 1, and it was confirmed that the heat generation temperature of the heating tool was raised to nearly 80° C. in all cases. Since the oxidation temperature of the iron powder contained in the exothermic composition is about 80 to 85° C., as in Examples 1 to 3, the air absorbing/releasing material 4 occupies the volume V1 of the inner space of the inner bag 3. When the ratio V2/V1 of the volume V2 of the space is 0.11 or more, a sufficient amount of air is supplied to the heat-generating composition, and the heat generation amount of the heat-generating composition can be maximized. can be brought to very high temperatures.

In addition, as is clear from FIG. 8, the heat generation temperature of the heating tool of Example 2 exceeds 70° C. even in a low temperature environment. It was found that a good thermal effect can be imparted.

Moreover, as is clear from FIG. 9, it was confirmed that the heating temperature of the heating tool of Example 1 decreased to about 40° C. when the heating tool was not used without being kneaded. Therefore, it was found that the heating temperature did not rise significantly when not in use, and that the heating tool did not always reach a high temperature.

REFERENCE SIGNS LIST 1 heating tool 2 exothermic composition 3 inner bag 4 air absorbing/releasing material

Claims (2)

an exothermic composition that generates heat upon contact with air;
an inner bag that is breathable by providing a plurality of perforations that allow both ventilation from the outside to the inside and from the inside to the outside;
an air absorbing/releasing material that has a space capable of containing air inside and deforms to absorb and/or release air;
The exothermic composition and the air absorbing/releasing material are sealed inside the inner bag,
At least part of the air absorbing/releasing material is sandwiched between the exothermic compositions inside the inner bag,
A ratio V2/V1 of the volume V2 of the space of the air absorbing/releasing material to the volume V1 of the internal space of the inner bag is 0.11 or more ,
wherein the air absorbing/releasing material is a sponge;
heating tool. 2. The heating tool according to claim 1, wherein said sponge is urethane sponge .

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