Warmer

Abstract

To provide a warmer having excellent heat generating characteristics both before and after storage.SOLUTION: A warmer 1 includes a sheet-like heat generating part 3 formed by disposing a heat generating layer 33 between two sheets 31 and 32, where at least one of them is an air permeable sheet. The sheet-like heat generating part 3 is configured to generate steam from the heat generating part 3 as heat is generated. The heat generating layer 33 contains a powder of an oxidizable metal, a powder of a carbon material, a powder of purified cellulose and water. The mass ratio of the content of the purified cellulose powder to the content of the oxidizable metal powder is 0.005 or more and 0.35 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heating device.

Background Art

[0002] Heating devices that utilize heat generation by the oxidation reaction of an oxidizable metal are variously known. Among such heating devices, some are designed to generate a large amount of steam as they generate heat. As such a heating device, for example, in Patent Document 1, a heating device provided with a heat generation layer of a powder composition containing an oxidizable metal, a water absorbent, and water has been proposed. Patent Document 2 proposes a heating device provided with a heat generation part in which a heat generation layer containing an oxidizable metal, a water absorbent, and water and a water retention layer formed from a water absorbent sheet are laminated. Patent Document 3 proposes a heating device provided with a heat generation layer of a powder composition containing an oxidizable metal, a carbon material, a porous substance, and water, the heat generation layer being a sheet-like material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the heating devices described in Patent Documents 1 to 3, it is desirable to stably generate heat and make the amount of steam generated as constant as possible. However, depending on the storage environment of the heating device, the heat generation characteristics of the heating device after storage may change compared to before storage, and as a result, it may not be possible to stably generate steam. Accordingly, an object of the present invention is to provide a heating device that is excellent in heat generation characteristics both before and after storage.

Means for Solving the Problems

[0005] The present invention includes a sheet-shaped heat generating part in which a heat generating layer is disposed between two sheets at least one of which is a breathable sheet, The sheet-shaped heat generating part is a heating device configured to generate steam from the heat generating part as it generates heat, The heat generating layer contains a powder of an oxidizable metal, a powder of a carbon material, a powder of purified cellulose, and water, The present invention provides a heating device in which the mass ratio of the content of the powder of purified cellulose to the content of the powder of the oxidizable metal is 0.005 or more and 0.35 or less.

[0006] The present invention also provides a method for manufacturing a sheet-shaped heat generating part, which includes applying a slurry containing a powder of an oxidizable metal, a powder of a carbon material, a powder of purified cellulose, and water onto a first sheet to form a coating layer, disposing a breathable second sheet on the coating layer, removing the water contained in the coating layer by heating, and supplying an aqueous electrolyte solution to the coating layer through the second sheet.

Advantages of the Invention

[0007] According to the present invention, a heating device excellent in heat generation characteristics is provided both before and after storage.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present invention will be described with reference to the drawings based on its preferred embodiments. The heating device of the present disclosure is used to contact a heating object during use and apply heat to the heating object. Examples of the heating object include the eyes, mouth, nose, and the surrounding skin and mucous membranes of humans, or the skin and mucous membranes in areas such as the throat, face, scalp, neck, arms, shoulders, legs, knees, abdomen, back, waist, and buttocks. However, the heating object is not limited to these, and the heating device of the present invention can also be applied to other parts of the human body. In addition, the heating device of the present invention can also be applied to heating objects other than humans.

[0010] Examples of the heating device of the present disclosure include, but are not limited to, the following aspects (a) to (e). (a) In the form of an eye mask configured to be held around the eyes. (b) In an adherent form configured to be held on the neck, arms, shoulders, legs, elbows, knees, forehead, abdomen, back, or waist of a human. (c) In the form of a face mask configured to be held around the mouth, nose, and the surrounding area, or the entire face. (d) In the form of a cup configured to be in contact with the mouth, nose, and the surrounding area. (e) In an adherent form configured to be held on clothing such as underwear. All the disclosures in this specification are applicable to all of the above aspects (a) to (e).

[0011] The heating device of the present disclosure includes a heat generating part. The heat generating part is preferably sheet-shaped and preferably contains (1) powder of a metal to be oxidized, (2) powder of a carbon material, (3) powder of purified cellulose, and (4) water. The powder of the metal to be oxidized has a function of generating heat accompanying an oxidation reaction with oxygen in the air, and enabling heat to be applied to an object to be heated. The powder of the carbon material has a function of promoting the oxidation reaction of the metal to be oxidized and efficiently generating heat. The powder of purified cellulose has a function of supplying water as a medium to the reaction system when promoting the oxidation reaction of the metal to be oxidized, thereby enhancing the heat generation efficiency, and has a function of making it difficult to change the heat generation characteristics of the sheet-shaped heat generating part during storage of the heating device of the present disclosure. Water has a function of facilitating the interaction between the powder of the metal to be oxidized and a carbon material or the like serving as a catalyst for the oxidation reaction. The heat generating part preferably includes a mixture containing the materials (1) to (4).

[0012] The heat generating part is preferably configured as a sheet-like object. A "sheet-like object" is a thin object having two opposing surfaces, a small thickness between the surfaces, and flexibility and shape retention. The thickness of the sheet-like object is preferably 0.6 mm or more, more preferably 0.8 mm or more, and still more preferably 1.0 mm or more. Also, the thickness of the sheet-like object is preferably 5.0 mm or less, more preferably 4.5 mm or less, and still more preferably 4.0 mm or less.

[0013] The heat generating part constituting the heating device is preferably configured to have a function of reacting with oxygen in the air to generate heat, and generating steam heated to a predetermined temperature from the heat generating part along with this heat generation. In this case, a part of the water contained in the heat generating part can become steam that evaporates along with the heat generation caused by the oxidation reaction of the metal to be oxidized.

[0014] The heating part preferably has a structure in which a heating layer is disposed between two sheets, at least one of which is a breathable sheet. This heating layer is preferably composed of a mixture containing the materials described in (1) to (4) above. The heating part may be used in this form as it is. Alternatively, the heating part may be used by being housed in a breathable packaging material. In this case, it is preferable that the packaging material does not allow solids to flow in and out. When the heating part is housed in the packaging material, the packaging material is separate from the heating part. That is, the packaging material does not constitute the heating part.

[0015] The shape of the packaging material is not particularly limited, but it is preferably flat. When forming the packaging material into a flat shape, it is preferable that the packaging material is formed by pasting the peripheral regions of both packaging materials together such that one surface is constituted by a first breathable packaging material and the other surface is constituted by a second packaging material having lower breathability than the first packaging material.

[0016] When the packaging material has a first breathable packaging material and a second packaging material having lower breathability than the first packaging material, the air permeability of the first packaging material is preferably 20 seconds / 100 mL or more, more preferably 30 seconds / 100 mL or more, and still more preferably 40 seconds / 100 mL or more. Also, the air permeability of the first packaging material is preferably 25000 seconds / 100 mL or less, more preferably 15000 seconds / 100 mL or less, and still more preferably 10000 seconds / 100 mL or less. The air permeability is measured according to JIS P8117:2009. In the present disclosure, when referring to "air permeability", it means the value measured by this method.

[0017] The moisture permeability of the first packaging material is preferably 480 g / (m 2 ·24h) or more, more preferably 720 g / (m 2 ·24h) or more, and still more preferably 960 g / (m 2 ·24h) or more. In addition, the water vapor permeability of the first packaging material is preferably 5000 g / (m 2 ·24 h) or less, more preferably 4750 g / (m 2 ·24 h) or less, and even more preferably 4500 g / (m 2 ·24 h) or less. By controlling the water vapor permeability of the first packaging material in this way, sufficient and appropriate heat generation characteristics can be exhibited, and water vapor can be sufficiently provided to the object to be heated. The water vapor permeability is measured in accordance with JIS Z0208. In the present disclosure, when referring to "water vapor permeability", it means the value measured by this method.

[0018] The first packaging material having the air permeability and water vapor permeability described above can be, for example, a resin film provided with a plurality of through holes, or a film obtained by uniaxially or biaxially stretching a sheet obtained from a resin composition containing polyethylene and a filler such as calcium carbonate. The air permeability can be appropriately changed by adjusting the degree of stretching.

[0019] On the other hand, the air permeability of the second packaging material is preferably 10000 seconds / 100 mL or more, more preferably 25000 seconds / 100 mL or more, and from the viewpoint of exhibiting sufficient and appropriate heat generation characteristics and sufficiently providing water vapor to the object to be heated, it is even more preferably non-ventilated. "Non-ventilated" means that the air permeability is 80000 seconds / 100 mL or more. As the second packaging material having the air permeability described above, for example, a resin film having fewer through holes than the first packaging material or a resin film having no through holes can be used.

[0020] The water vapor permeability of the second packaging material is preferably 480 g / (m 2 ·24 h) or less, more preferably 240 g / (m 2 ·24 h) or less, and even more preferably 0 g / (m 2 ·24 h). By controlling the water vapor permeability of the second packaging material in this way, sufficient and appropriate heat generation characteristics can be exhibited, and water vapor can be sufficiently provided to the object to be heated.

[0021] One embodiment of the heat generating part described above is shown, for example, in FIG. 1. The heat generating part 3 shown in the figure is shown as a sheet-like heat generating part in which a heat generating layer 33 is disposed between a pair of sheets 31 and 32. The heat generating layer 33 is composed of a heat generating composition 30 containing a powder of an oxidizable metal 3a, a powder of a carbon material 3b, and a powder of purified cellulose 3c, and water. At least one of the pair of sheets 31 and 32 is a breathable sheet. Thereby, supply of air (oxygen) to the heat generating layer 33 through the breathable sheet is achieved. When the sheets 31 and 32 are water-absorbent, water is contained not only in the heat generating layer 33 but also in the sheets 31 and 32.

[0022] The heat generating part 3 shown in FIG. 1 is housed in a pair of packaging materials 36 composed of a first packaging material 34 and a second packaging material 35 to become a warming device 1 as shown in FIG. 2, for example.

[0023] It is preferable that the content ratio of the oxidizable metal and the purified cellulose in the heat generating layer of the heat generating part constituting the warming device of the present disclosure satisfies a predetermined range. Specifically, when the content of the powder of the oxidizable metal contained in the heat generating layer is W1 and the content of the purified cellulose is W2, from the viewpoint of promoting the oxidation reaction of the oxidizable metal and obtaining a warming device having excellent heat generating characteristics both before and after storage of the warming device, the value of W2 / W1, which is the mass ratio of W2 to W1, is preferably 0.005 or more, more preferably 0.01 or more, and still more preferably 0.02 or more. From the same viewpoint, the value of W2 / W1 is preferably set to 0.35 or less, more preferably 0.30 or less, and still more preferably 0.25 or less. Taking the above into consideration, in the warming device of the present disclosure, the value of W2 / W1 is preferably 0.005 or more and 0.35 or less, more preferably 0.01 or more and 0.30 or less, and still more preferably 0.02 or more and 0.25 or less.

[0024] It is also preferable that the content ratio of the purified cellulose and water in the heat generating layer of the heat generating part constituting the warming device of the present disclosure satisfies a predetermined range. Specifically, when the content of the purified cellulose powder contained in the heat-generating layer is W2 and the water content is W3, from the viewpoint of sufficiently advancing the oxidation reaction of the metal to be oxidized and improving the heat generation characteristics and the amount of water vapor generated, the value of W2 / W3, which is the mass ratio of W2 to W3, is preferably set to 0.05 or more, more preferably 0.07 or more, and even more preferably 0.10 or more. From the viewpoint of the water retention ability of the purified cellulose powder, the value of W2 / W3 is preferably set to 0.60 or less, more preferably 0.50 or less, and even more preferably 0.40 or less. Taking the above into consideration, in the heating device of the present disclosure, the value of W2 / W3 is preferably 0.05 or more and 0.60 or less, more preferably 0.07 or more and 0.50 or less, and even more preferably 0.10 or more and 0.40 or less.

[0025] It is also preferable that the heat-generating part constituting the heating device of the present disclosure satisfies a predetermined range in the content ratio of the metal to be oxidized and water in the heat-generating layer. Specifically, when the content of the powder of the metal to be oxidized contained in the heat-generating layer is W1 and the water content is W3, even when the content of the metal to be oxidized is less than that of the conventional heating device, from the viewpoint of being able to exhibit heat generation characteristics equivalent to or better than those of the conventional device, the value of W3 / W1, which is the mass ratio of W3 to W1, is preferably set to 0.25 or more, more preferably 0.27 or more, and even more preferably 0.30 or more. From the viewpoint of efficiently advancing the oxidation reaction of the metal to be oxidized and obtaining a heat-generating body with excellent heat generation characteristics, the value of W3 / W1 is preferably set to 0.60 or less, more preferably 0.55 or less, and even more preferably 0.50 or less. Taking the above into consideration, in the heating device of the present disclosure, the value of W3 / W1 is preferably 0.25 or more and 0.60 or less, more preferably 0.27 or more and 0.55 or less, and even more preferably 0.30 or more and 0.50 or less.

[0026] It is preferable that the moisture content of the heat-generating layer constituting the heating device of the present disclosure satisfies a predetermined range. Specifically, the moisture content of the heat-generating layer is R H2OWhen doing so, from the viewpoint of sustaining the oxidation reaction of the metal to be oxidized, the moisture content R H2O is preferably set to 12% or more, more preferably 14% or more, and still more preferably 16% or more. From the viewpoint of efficiently advancing the oxidation reaction of the metal to be oxidized and obtaining a heating element excellent in heat generation characteristics, the moisture content R H2O is preferably set to 30% or less, more preferably 28% or less, and still more preferably 26% or less. Taking the above into consideration, in the heating device of the present disclosure, the moisture content R H2O is preferably 12% or more and 30% or less, more preferably 14% or more and 28% or less, and still more preferably 16% or more and 26% or less.

[0027] The moisture content R in the heat generating part H2O and the amount of water W3 contained in the heat generating layer are calculated by the following method. First, 2 g of the heat generating layer is used as a measurement sample, the measurement sample is set on the sample dish of a moisture meter (Kett Moisture Meter FD-240, manufactured by Kett Science Laboratory Co., Ltd.), and the amount of moisture released when dried at 120 °C for 15 minutes is measured. The moisture content R of the heat generating layer is obtained according to the following formula (A). H2O Next, the obtained moisture content R H2O is substituted into the following formula (B) to calculate the amount of water W3 contained in the heat generating layer. Moisture content (R H2O ) of the heat generating layer = amount of moisture released / sample amount (2 g) ··· (A) Moisture amount (W3) of the heat generating layer = total amount of water added to the heat generating part (g) × solid content ratio in the heat generating composition (total value of composition ratios excluding water / total value of composition ratios) × moisture content R H2O / (1 - moisture content R H2O ) ··· (B)

[0028] Examples of the powder of the metal to be oxidized constituting the heat generating layer include powders such as iron, aluminum, zinc, manganese, magnesium, and calcium. These can be used alone or in combination of two or more. Among these, from the viewpoints of handleability, safety, and manufacturing cost, it is preferable to use metallic iron. That is, iron powder is preferably used. Examples of the iron powder include one or more selected from reduced iron powder and atomized iron powder. The powder of the oxidizable metal constituting the exothermic layer may be an aggregate of metal particles having no pores on the particle surface, or may be an aggregate of porous metal particles.

[0029] When the powder of the oxidizable metal is composed of particles having pores on the surface, the pore diameter D2 of the particles constituting the powder of the oxidizable metal is preferably 0.001 μm or more, more preferably 0.003 μm or more, and still more preferably 0.006 μm or more. The pore diameter D2 of the particles constituting the powder of the oxidizable metal is preferably 0.07 μm or less, more preferably 0.05 μm or less, and still more preferably 0.01 μm or less. By setting it within such a range, water can be efficiently drawn into the oxidizable metal side. As a result, the oxidation reaction of the oxidizable metal can be further promoted, and the exothermic characteristics can be further enhanced. Such a powder of the oxidizable metal can be produced, for example, by the method disclosed in EP3626367A1.

[0030] The pore diameter D2 of the powder of the oxidizable metal described above can be measured by the following method using the mercury intrusion method defined in JIS R1655, for example. Specifically, 0.02 g to 0.1 g of the powder of the oxidizable metal is used as a measurement sample, and a measurement cell containing the measurement sample is set in a mercury porosimeter (for example, AutoPore IV9500, manufactured by Micromeritics), and the cumulative pore volume V (cm 3 / g) of the measurement sample is measured when the mercury injection pressure P is increased within a predetermined range. Then, with the converted pore diameter D (μm) calculated according to the following formula (C) on the horizontal axis, log differential pore volume (dV / d(log 10 D); cm 3Plot the relationship with ( / g) on the vertical axis to obtain the pore volume distribution. That is, take the converted pore diameter D on the horizontal axis and the pore volume obtained by differentiating the cumulative pore volume V with respect to the logarithmic value of the pore diameter D on the vertical axis to obtain the pore volume distribution. D = 4γcosθ / P ···(C) (γ: surface tension of mercury, θ: contact angle, P: mercury injection pressure)

[0031] The above measurement is carried out in an environment of 22°C and 65% RH. The surface tension γ of mercury is 480 dyn / cm, the contact angle θ is 140°, and the mercury injection pressure P is in the range of 0 psia (0 MPa) or more and 60,000 psia (413.685 MPa) or less. Based on the distribution curve of the converted pore diameter D obtained under this measurement condition, the cumulative total value of the converted pore diameter D in the range of 0.0018 μm or more and 100 μm or less is taken as the cumulative pore volume V (mL / g), and the median value of the pore diameter in the distribution curve is taken as the pore diameter D2 (μm) of the present disclosure.

[0032] From the viewpoint of appropriately controlling the oxidation reaction to obtain a heating device with good heat generation characteristics, the powder of the oxidizable metal preferably has a particle size of 1 μm or more, more preferably 10 μm or more, for the particles constituting the powder. From the same viewpoint, the particle size of the particles constituting the powder of the oxidizable metal is preferably 200 μm or less, more preferably 100 μm or less.

[0033] The particle size of the powder of the oxidizable metal can be, for example, the median diameter measured by the laser diffraction / scattering method using a laser diffraction / scattering particle size distribution measuring device (manufactured by Horiba, Ltd., model number: LA-950V2).

[0034] As the powder of the carbon material constituting the heat generation layer, those having a function for promoting the oxidation reaction, specifically, having one or more functions as an oxygen retention supply material to the oxidizable metal and a catalytic ability can be used. Examples of such carbon materials include activated carbons such as coconut shell charcoal, charcoal powder, bituminous coal, peat, and lignite, carbon black, acetylene black, and powders such as graphite. These can be used alone or in combination of two or more. Among these, from the viewpoint of having a good balance between oxygen supply ability and catalytic ability, activated carbon powder is preferably used as the carbon material powder.

[0035] From the viewpoint of sufficiently expressing the catalytic ability of the oxidation reaction and obtaining a heating device with good heat generation characteristics, the particle size of the particles constituting the carbon material powder is preferably 1 μm or more, more preferably 10 μm or more. From the same viewpoint, the particle size of the particles constituting the carbon material powder is preferably 200 μm or less, more preferably 100 μm or less. The carbon material powder can be measured by the same method as the method for measuring the particle size of the powder of the metal to be oxidized.

[0036] The purified cellulose powder constituting the heat generating layer is a powder composed of a polymer in which β-glucose is polymerized. Conventionally, in heating devices capable of generating a large amount of water vapor, in order to control the amount of water present in the heat generating part, a water-absorbing resin may be contained in the heat generating part. On the other hand, in the heating device of the present disclosure, purified cellulose powder is used for the purpose of controlling the amount of water present in the heat generating part. Therefore, in the heating device of the present disclosure, it is not essential to contain a water-absorbing resin in the heat generating part. However, containing a water-absorbing resin in the heat generating part is not prohibited.

[0037] The purified cellulose constituting the heat generating layer is highly pure cellulose obtained by removing lignin and the like from natural cellulose fibers. Therefore, for example, a material simply powdered that contains natural cellulose fibers such as wood powder does not correspond to the purified cellulose powder referred to in the present disclosure. As is clear from the comparative examples described later, even if wood powder is contained in the heat generating part, a heating device having sufficient heat generation characteristics cannot be obtained. The purified cellulose referred to in the present disclosure preferably has a cellulose content of 90% by mass or more. The cellulose content can be measured by the holocellulose quantification method described on pages 1081 to 1082 of the Analytical Chemistry Handbook (Revised Fourth Edition, November 30, 1991, published by Maruzen Co., Ltd.) edited by the Japanese Society for Analytical Chemistry.

[0038] Examples of natural cellulose fibers used as raw materials for purified cellulose include seed hair fibers such as cotton and kapok, bast fibers such as flax, hemp, ramie, jute, kozo, and mitsumata, leaf vein fibers such as Manila hemp and sisal hemp, stem fibers such as bamboo and straw, hardwood fibers such as beech, birch, and poplar, and softwood fibers such as pine, cedar, and fir.

[0039] From the viewpoint of improving the mixability with powders of oxidizable metals and carbon materials, the particle size of the purified cellulose powder is preferably 10 μm or more, more preferably 15 μm or more, and still more preferably 20 μm or more. From the same viewpoint, the particle size of the purified cellulose powder is preferably 200 μm or less, more preferably 150 μm or less, and still more preferably 100 μm or less. Taking the above into consideration, the particle size of the purified cellulose powder is preferably 10 μm or more and 200 μm or less, more preferably 15 μm or more and 150 μm or less, and still more preferably 20 μm or more and 100 μm or less. The particle size of the purified cellulose powder can be, for example, the median diameter measured at a temperature of 25°C by the laser diffraction scattering method using a laser diffraction / scattering type particle size distribution measuring device (manufactured by Horiba, Ltd., model number: LA-920).

[0040] The aspect ratio (length / width) of the purified cellulose powder is preferably 2 or less, more preferably 3 or less, and still more preferably 4 or less. By using the purified cellulose powder having such an aspect ratio, the mixability with other powders constituting the heat-generating layer is improved, and consequently, the heat-generating characteristics of the heating device after storage are less likely to change. In the present disclosure, the aspect ratio of the purified cellulose powder is defined as the value of L / W, where L is the length of the first line segment (major axis) with the longest traversing length in the projection image of the powder, and W is the length of the second line segment (minor axis) that is orthogonal to the first line segment and has the longest traversing length.

[0041] It is known that purified cellulose includes crystalline and amorphous forms. As the purified cellulose used in the heating device of the present disclosure, either crystalline or amorphous form can be used. Among these, from the perspective of the handleability of the slurry containing the powder of the metal to be oxidized, the powder of the carbon material, the powder of the purified cellulose, and water, it is preferable to use purified cellulose.

[0042] Generally, several crystal structures of cellulose are known, and the crystallinity may be defined based on the ratio of the amorphous part and the crystal part present in part. The "crystallinity" in the present disclosure refers to the crystallinity of type I derived from the crystal structure of natural cellulose, and is defined by the crystallinity represented by the following formula (1) obtained from the powder X-ray diffraction spectrum.

[0043] Crystallinity (%) = [(I 22.6 - I 18.5 ) / I 22.6 × 100 (1) In the formula, I 22.6 represents the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6°) in X-ray diffraction, and I 18.5 represents the diffraction intensity of the amorphous part (diffraction angle 2θ = 18.5°).

[0044] The measurement conditions of the powder X-ray diffraction spectrum were as follows: X-ray source: Cu / Kα-radiation, tube voltage: 40 kv, tube current: 120 mA, measurement range: diffraction angle 2θ = 5 to 45°, and X-ray scan speed: 10° / min. The powder of the purified cellulose was used as a measurement sample after being compression-molded into a pellet with an area of 320 mm 2 × thickness of 1 mm.

[0045] In the present disclosure, when the crystallinity of the purified cellulose calculated by formula (1) is 33% or less, the purified cellulose is defined as amorphous. The powder of amorphous purified cellulose can be produced, for example, by the method described in JP-A-2011-001547 according to the applicant's previous application.

[0046] As the powder of purified cellulose, both solid and porous powders can be used. When the powder of purified cellulose is porous, the degree of porosity is preferably 1.5 mL / g or more, more preferably 2.0 mL / g or more, still more preferably 2.5 mL / g or more, even more preferably 3.0 mL / g or more, and still even more preferably 4.0 mL / g or more, expressed in terms of pore volume. Also, the pore volume of the powder of purified cellulose is preferably 8.0 mL / g or less, more preferably 7.0 mL / g or less, still more preferably 6.0 mL / g or less, and even more preferably 5.0 mL / g or less. The pore volume is a value obtained by normalizing the total volume of mercury that has penetrated into the pores inside the porous cellulose particles and the gaps between the particles, measured by the mercury intrusion method, by dividing it by the mass of the particles.

[0047] Commercially available products can also be used as the powder of purified cellulose. Examples of such commercially available products include KC Flock (registered trademark) of Nippon Paper Industries Co., Ltd., Avicel (registered trademark) of FMC Corporation, and Theolas (registered trademark) of Asahi Kasei Chemicals.

[0048] The heating layer constituting the heating part preferably contains an electrolyte from the viewpoint of facilitating the generation of water vapor accompanying the heating of the heating part. Examples of the electrolyte include salts of an alkali metal or alkaline earth metal with phosphoric acid or sulfuric acid, or one or more of chlorides or hydroxides of an alkali metal or alkaline earth metal. Among these, from the viewpoints of excellent chemical stability and production cost, it is preferable to use one or more of potassium phosphate, potassium hydroxide, sodium chloride, and potassium chloride as the electrolyte. The electrolyte may be used, for example, in powder form, or may be used as a liquid dissolved or dispersed in a liquid medium such as water.

[0049] The heat-generating layer constituting the heat-generating part may be composed only of a powder of an oxidizable metal, a powder of a carbon material, a powder of purified cellulose, and water, or may contain other components in addition to these. Examples of other components include one or more of the water-absorbing resin described below and the electrolytes described above. Also, various thickeners such as xanthan gum can be used. The content ratio of other components in the heat-generating part, from the viewpoint of further improving the heat-generating characteristics and the amount of water vapor generated, is preferably 20% by mass or less, more preferably 10% by mass or less, expressed as the total mass ratio to the total solid content constituting the heat-generating part. The total mass ratio of the powder of the oxidizable metal, the powder of the carbon material, and the powder of purified cellulose to the total solid content constituting the heat-generating part is preferably 80% by mass or more, more preferably 90% by mass or more, both before and after storage, from the viewpoint of obtaining excellent heat-generating characteristics and from the viewpoint of further improving the heat-generating characteristics and the amount of water vapor generated. When the water-absorbing resin is included as other components, its mass is based on the mass in the absolutely dry state.

[0050] As described above, the heat-generating part is formed by disposing a heat-generating layer between two sheets, at least one of which is a breathable sheet. The two sheets may (a) both have breathability, or (b) only one of the two sheets may have breathability. In the case of (a), the two sheets may be the same sheet or different sheets. In either case, the breathable sheet preferably has an air permeability of 25,000 seconds / 100 mL or less. As such a sheet having such an air permeability, for example, fiber sheets such as tissue paper, absorbent paper, crepe paper, non-woven fabric, or mesh sheets can be used. In the case of (b), one of the two sheets may be a breathable sheet having an air permeability of 10,000 seconds / 100 mL or less as described above, and the other may be a non-breathable sheet having an air permeability of 80,000 seconds / 100 mL or more. Examples of the non-breathable sheet include laminated paper formed by laminating a synthetic resin film on paper.

[0051] In either case of (a) and (b) described above, neither of the two sheets constituting the heat generating part contains a water-absorbing resin described later. When the heat generating part contains the water-absorbing resin described later, it is common to add a mineral acid or its salt to the heat generating part for the purpose of suppressing hydrogen gas generated by the reaction between the water-absorbing resin and the metal to be oxidized during storage of the warming device. However, when the heat generating part contains a mineral acid or its salt, when the heat generating part generates heat, the metal to be oxidized may react with the mineral acid or its salt, resulting in poor heat generation. However, when the heat generating part does not contain a water-absorbing resin, there is an advantage that unintended poor heat generation does not occur because it is not necessary to contain a mineral acid or its salt in the heat generating part. The generation of gas is a cause of expansion, which is a factor in the deterioration of the appearance of the warming device. The fact that the heat generating part does not contain a water-absorbing resin is also advantageous in that it can reduce the bending load peak of the warming device and improve the adhesion to the object to be heated. Examples of the mineral acid or its salt include phosphoric acid and alkali metal salts of phosphoric acid.

[0052] From the viewpoint of increasing the manufacturing efficiency of the warming device, it is also preferable that the heat generating part has a water-absorbing resin. When arranging a water-absorbing resin in the heat generating part, it is more preferable to accommodate the heat generating part in a packaging material and arrange a layer containing a powder of the water-absorbing resin between the heat generating layer in the heat generating part and the packaging material.

[0053] As a result of the inventor's research, it has been found that the synergistic effect of the heat generating part having a water-absorbing resin and having a powder of purified cellulose enhances the storage stability of the warming device and enables stable generation of steam. In addition to the above advantages, by having a water-absorbing resin in the heat generating part, it is possible to absorb excess moisture present in the heat generating part. As a result, the oxidation reaction of the oxidizable metal can proceed efficiently to improve the heat generation characteristics, and the moisture held in the water-absorbing resin and the heat generating part can be continuously released as water vapor, so that a comfortable warm feeling can be given to the user of the warming device.

[0054] When disposing a water-absorbing resin in the heat generating part, an aspect of disposing a layer containing a powder of the water-absorbing resin adjacent to the heat generating layer in the heat generating part can be mentioned. As such an aspect, for example, there is an aspect in which the powder of the water-absorbing resin has a single layer formed by being sandwiched between one or two different moisture-permeable sheets.

[0055] One form of the heat generating part containing a powder of the water-absorbing resin is illustrated in FIG. 3. In the embodiment shown in the figure, among the pair of sheets 31 and 32 in the heat generating part 3 shown in FIG. 1, a water-absorbing resin-containing sheet 3L is used instead of the sheet 32. The water-absorbing resin-containing sheet 3L has a single-layer structure in which the powder of the water-absorbing resin 37 is sandwiched between two moisture-permeable sheets 38 and 39. Such a water-absorbing resin-containing sheet of this form is described, for example, in Japanese Patent Laid-Open No. 8-246395 according to the applicant's previous application. Since the heat generating part 3 has such a configuration, while continuously exhibiting excellent heat generation characteristics, water vapor can be continuously released, and more water vapor can be generated than in conventional warming devices. Therefore, it is possible to continuously perceive both a comfortable warm feeling and moisture on the heating target such as the eyes, nose, and throat. The heat generating part 3 having such a configuration is advantageous in that, for example, by applying it to a warming device in the form of an eye mask or an adhesive form, a warm feeling can be continuously perceived at the application site such as the user's eyes and the surroundings thereof, giving the user a sense of comfort.

[0056] When the heat generating part contains a water-absorbing resin, for the purpose of suppressing the generation of hydrogen gas due to the reaction between the water-absorbing resin and the metal to be oxidized, it is preferable to add a mineral acid salt to the heat generating part.

[0057] Since the heating device of the present disclosure is for bringing this into contact with an object to be heated and applying heat to the object to be heated, it is desired that the adhesiveness with the object to be heated is high. From this viewpoint, the heating device preferably has a bending load peak in the state before heating of 1.5 N or less, more preferably 1.0 N or less, and still more preferably 0.5 N or less. The lower the value of the bending load peak of the heating device, the more desirable it is in terms of increasing the adhesiveness with the object to be heated. However, if the value is as small as about 1.0 N, the adhesiveness with the object to be heated will be sufficiently high. In order to make the bending load peak of the heating device equal to or less than the above-described value, for example, as described above, a heat generating part that does not contain a water-absorbing resin can be used, or when the heat generating part contains a water-absorbing resin, means such as reducing the content of the water-absorbing resin can be adopted. The method for measuring the bending load peak of the heating device will be described in the examples described later.

[0058] Specific examples of the water-absorbing resin include starch, crosslinked carboxymethylated cellulose, polymers or copolymers of acrylic acid or alkali metal salts of acrylic acid, etc., and one or more of polyacrylic acid and its salts and polyacrylate graft polymers. As the polyacrylate, a sodium salt can be used. In addition, examples of the shape of the water-absorbing resin include particles in the form of spheres, lumps, clusters, fibers, or combinations thereof. The water-absorbing resin is preferably a powder composed of an aggregate of particles. When the water-absorbing resin is used as a powder, the particle size of the particles constituting the powder can be within the range usually used in the technical field.

[0059] The heat generating part in the heating device of the present disclosure can be manufactured, for example, by the following method. When manufacturing a sheet-like heat generating part having, for example, the structure shown in FIG. 1 as the heat generating part, a heat generating composition 30 containing a powder of an oxidizable metal 3a, a powder of a carbon material 3b, and a powder of purified cellulose 3c is applied to one surface of a first sheet 31 to form a coating layer. For the purpose of facilitating the formation of this coating layer, it is preferable to contain water in the heat generating composition 30 to make the heat generating composition 30 into a slurry state. The first sheet 31 may have air permeability or may be airtight, but from the viewpoint of preventing the heat generating composition 30 from oozing out through the first sheet 31, the first sheet 31 is preferably airtight.

[0060] Next, a second sheet 32 is disposed on the coating layer so as to cover the coating layer. As a result, the coating layer is sandwiched between the two sheets 31 and 32. As the second sheet 32, one having air permeability is used.

[0061] The water contained in the coating layer is removed while the coating layer is sandwiched between the two sheets 31 and 32. As a result, the coating layer changes into a layer mainly composed of solid content. The removal of water is achieved, for example, by heating the coating layer. Specific means of heating include, for example, contact with a drum dryer, blowing of hot air, irradiation with infrared rays, heating in a heating furnace, and the like.

[0062] Next, an electrolyte aqueous solution is supplied to the coating layer in a state where the water has been removed. The supply of the electrolyte aqueous solution can be performed through the second sheet 32 which is an air-permeable sheet. As the electrolyte contained in the electrolyte aqueous solution, those exemplified above can be used. The concentration of the electrolyte contained in the electrolyte aqueous solution and the supply amount of the electrolyte aqueous solution can be appropriately set according to the specific composition of the heat generating layer in the finally obtained heat generating part.

[0063] The supply amount of the aqueous electrolyte solution is preferably such that the mass ratio of the water content in the aqueous electrolyte solution to the content of the oxidizable metal contained in the sheet-shaped heating part is 0.40 or more and 0.90 or less, more preferably 0.45 or more and 0.85 or less, and still more preferably 0.50 or more and 0.80 or less. By supplying the aqueous electrolyte solution so that the ratio of the oxidizable metal to water is like this, it is possible to ensure a sufficient calorific value and water vapor generation amount.

[0064] When a mineral acid or its salt is contained in the heating part, from the viewpoint of reacting with the oxidizable metal and preventing the oxidation of the oxidizable metal, the mass ratio of the content of the mineral acid and its salt to the water content in the heating part is preferably 0.04 or less, more preferably 0.01 or less, and particularly preferably 0. By the above procedure, the target sheet-shaped heating part 3 can be obtained.

[0065] In the sheet-shaped heating part manufactured by the above method, regardless of which form shown in FIGS. 1 and 3 it is, at least one of the two sheets 31, 32 may contain water. In that case, a part of the water applied to the heating layer by the supply of the aqueous electrolyte solution is retained by at least one or both of the sheets 31, 32. In other words, the water applied by the supply of the aqueous electrolyte solution is retained by the heating layer 33 and at least one or both of the sheets 31, 32.

[0066] The heating device of the present disclosure preferably includes a main body part and the heating part provided in the main body part. The main body part preferably has a shape that covers the object to be heated during use. The heating device preferably includes a front surface sheet located on the side closer to the object to be heated and a back surface sheet located on the side farther from the object to be heated. Specifically, the heating device preferably includes a front surface sheet located on the side closer to the user's skin and a back surface sheet located on the side farther from the user's skin. The heating device preferably has the main body part constituted by the front surface sheet and the back surface sheet. The heat generating part is preferably held between the front sheet and the back sheet that constitute the main body part. It is also preferable that the heat generating part is held between the front sheet and the back sheet while being housed in a breathable packaging material.

[0067] When the packaging material is formed by a first packaging material and a second packaging material, the breathable first packaging material is preferably arranged on the side closer to the object to be heated, specifically, on the side closer to the user's skin. That is, the first packaging material is preferably arranged to face the front sheet. When the packaging material is formed by a first packaging material and a second packaging material, the second packaging material with lower breathability than the first packaging material is preferably arranged on the side farther from the object to be heated, specifically, on the side farther from the user's skin. That is, the second packaging material is preferably arranged to face the back sheet. It is also preferable that the heating device is configured to generate water vapor heated to a predetermined temperature. Thereby, heat can be applied to the object to be heated and its surroundings.

[0068] Hereinafter, an embodiment of the heating device will be described with reference to FIGS. 4 to 7. FIG. 4 shows a heating device 1 having a form of a so-called eye mask as an embodiment of the heating device. The heating device of the embodiment shown in FIG. 4 is configured to be able to be held on and around the eyes. This heating device is used to abut so as to cover both eyes of a human, which is the object to be heated, during use, and apply heat to the eyes and their surroundings. The heating device is configured to generate water vapor heated to a predetermined temperature, and thereby heat can be applied to the eyes and their surroundings, which are the objects to be heated.

[0069] The heating device of the present embodiment preferably includes a horizontally long main body part having a shape that covers both eyes of the user during use, and a heat generating part provided on the main body part. Further, it is also preferable that the heating device of the present embodiment includes a pair of ear-hanging portions attached to the main body portion. The ear-hanging portions enable the covering state of both eyes of the user to be maintained. The ear-hanging portions have insertion portions through which the ears of the user pass. In the following description according to the present embodiment, the direction corresponding to the longitudinal direction of the heating device is also referred to as the lateral direction, and the direction orthogonal to the lateral direction is also referred to as the longitudinal direction. In the heating device according to the present embodiment, in FIG. 4, the heating device 1, the main body portion 2, the heat generating portion 3, the ear-hanging portion 4, the insertion portion 4A, the lateral direction X, and the longitudinal direction Y are illustrated as examples.

[0070] In the heating device 1 shown in FIG. 4, the ear-hanging portions 4 are provided at both outer end regions in the lateral direction X of the main body portion 2 and can be inverted outward in the lateral direction X. Thus, by hanging each of the ear-hanging portions 4, 4 on the ears of the user, the covering state of both eyes of the user by the main body portion 2 can be maintained. From the viewpoint of improving the wearing comfort, the sheet material constituting the ear-hanging portion 4 is preferably a sheet having elasticity.

[0071] The heating device 1 shown in FIG. 5 has a so-called sticking form. The heating device 1 of the present embodiment preferably includes a main body portion 2 having a front surface sheet 5 that constitutes a skin-facing surface during use and a back surface sheet 6 that constitutes a non-skin-facing surface during use, and a heat generating portion 3 provided in the main body portion 2. The heat generating portion 3 is preferably held between the front surface sheet 5 and the back surface sheet 6 that constitute the main body portion 2. It is also preferable that the heat generating portion 3 is held between the front surface sheet 5 and the back surface sheet 6 that constitute the main body portion 2 in a state of being housed in a breathable packaging material 36.

[0072] In the present embodiment, it is preferable that the front surface sheet 5 that constitutes the skin-facing surface is provided with an adhesive portion 51 in a part or the whole of the outer surface thereof. The adhesive portion 51 is for holding the heating device 1 at a site where heat and water vapor generated from the heating device 1 are applied. By providing the adhesive portion 51, it can be directly attached to the user's skin or attached to the user's clothing for use, and the heating device 1 can be easily held at a predetermined portion that is the object to be heated. In addition, in order to exhibit the adhesiveness of the adhesive portion at a desired timing, a base material such as a film that covers the adhesive portion may be provided.

[0073] The heating device 1 shown in FIG. 6 has a form of a so-called face mask. The heating device 1 of the present embodiment preferably includes a main body portion 2 that covers at least one of the user's mouth and nose during use, and a heat generating portion 3 provided in the main body portion 2. In addition to this, the heating device 1 of the present embodiment preferably includes a pair of ear-hanging portions 4 provided at both left and right ends of the main body portion 2. The ear-hanging portions enable the covering state of at least one of the user's mouth and nose to be maintained. The ear-hanging portion 4 is composed of, for example, a sheet material separate from the main body portion 2. In this case, the main body portion 2 and the ear-hanging portion 4 are joined in a joining region indicated by reference numeral 9 in FIG. 6. An insertion portion 4A is preferably formed in the central region of the ear-hanging portion 4. The heat generating portion 3 is preferably held between a front surface sheet 5 and a back surface sheet 6 that constitute the main body portion 2. The heat generating portion 3 is also preferably held between the front surface sheet 5 and the back surface sheet 6 that constitute the main body portion 2 while being housed in a breathable packaging material 36.

[0074] As shown in FIG. 6, the heating device 1 of the present embodiment preferably has a folding line 15 at a position corresponding to the user's nasal bridge. The folding line 15 is provided in the central region in the lateral direction of the main body portion 2 in the heating device 1. With such a configuration, when the heating device 1 in the form of a face mask is used, the front surface sheet 5 can be brought into close contact along the convex shape of the nose with the folding line 15 as a flexible axis, so that a gap between the heating device 1 and the object to be heated is less likely to occur, and the heating and humidifying effect can be enhanced. Alternatively, depending on the use and the like, the heating device 1 may be in a flat shape without the folding line 15.

[0075] The heating device 1 shown in FIG. 7 has a so-called cup shape. The heating device 1 of the present embodiment preferably includes a main body portion 2 that covers at least one of the user's mouth and nose during use, and a heat generating portion 3 provided in the main body portion 2. The heating device 1 may or may not include an ear-hanging portion that can maintain the covering state of at least one of the user's mouth and nose according to its use.

[0076] As shown in FIG. 7, the heating device 1 preferably has a main body portion 2 formed by continuously connecting a first panel portion 21 and a second panel portion 22 having substantially the same shape as the first panel portion 21. In the present embodiment, both panel portions 21 and 22 are formed in a fan shape, and it is preferable that the tapered portions of both panel portions 21 and 22 are continuously joined. Both the first panel portion 21 and the second panel portion 22 are each composed of a continuous front surface sheet 5 and a continuous back surface sheet 6, and it is preferable that the heat generating portion 3 is held between the front surface sheet 5 and the back surface sheet 6. It is also preferable that the heat generating portion 3 is held between the front surface sheet 5 and the back surface sheet 6 that constitute the main body portion 2 while being housed in a breathable packaging material 36.

[0077] The heating device 1 in the present embodiment preferably has a boundary line D serving as a flexible axis for bending the main body portion 2 at the continuous portion between the first panel portion 21 and the second panel portion 22. In the present embodiment, it is preferable that the first panel portion 21 and the second panel portion 22 have a shape that is line-symmetric about the boundary line D. The heating device 1 of the present embodiment is bent so that the surface sheets 5 face each other with the boundary line D as the axis, and the first side edge 21A of the first panel portion 21, the first side edge 22A of the second panel portion 22, and the second side edge 21B of the first panel portion 21 and the second side edge 22B of the second panel portion 22 are overlapped and joined respectively. In both panel portions 21 and 22, the third side edges 21C of the first panel portion 21 and the third side edges 22C of the second panel portion 22, which are located outside, are not joined to each other, and an opening in the cup shape is formed. It is preferable that this opening is open to such an extent that it can cover the nose and mouth of the user. As a result, a bottomed cylindrical cup-shaped heating device with the boundary line D and the positions in its vicinity as the bottom is formed. The outer surface of this cup-shaped heating device is formed by the back sheet 6, and the inner surface is formed by the surface sheet 5.

[0078] Regarding the ear-hanging portion, the surface sheet and the back sheet, and the various sheet materials that can be used for the base material sheet, the packaging material, and the moisture-permeable sheet in the heating device shown in FIGS. 4 to 7, they can be appropriately determined independently in consideration of their air permeability, moisture permeability, texture, stretchability, strength, and prevention of leakage of the constituent materials of the heat-generating composition, etc. As the sheet material, for example, fiber sheets such as non-woven fabrics, woven fabrics, and paper, resin foam sheets, metal sheets, or combinations thereof are used. The sheet material may have a single structure consisting of only one sheet material, whether single-layer or multi-layer, or may have a laminated structure in which two or more sheet materials are overlapped.

[0079] As described above, the present invention has been described based on its preferred embodiments, but the present invention is not limited to the above embodiments. In the heating device of the embodiment shown in FIGS. 4 to 7, the two heat-generating portions are held apart, but the number and arrangement form of the heat-generating portions are not particularly limited as long as a temperature sensation can be imparted to the object to be heated and its surroundings.

Example

[0080] Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “mass %”.

[0081] [Example 1] <Preparation of Paint> Iron powder (manufactured by DOWA IP Creation Co., Ltd., RKH3, particle size: 45 μm) was used as the powder of the metal to be oxidized. Activated carbon powder (manufactured by Osaka Gas Chemical Co., Ltd., Carboraffin, particle size: 31 μm) was used as the powder of the carbon material. Cellulose powder (manufactured by Nippon Paper Industries Co., Ltd., product name: KC Flock, brand: W-400G, particle size: 24 to 50 μm, crystallinity 77%, cellulose content: 99%) was used as the powder of the purified cellulose. Xanthan gum was used as the thickener. These were mixed with water to prepare an exothermic composition.

[0082] <Fabrication of Sheet-like Exothermic Part> The above-mentioned exothermic composition was applied by the die coating method on one side of a laminate paper (manufactured by Nitto Kako Co., Ltd.) obtained by laminating polyethylene and thin paper to form a coating layer. Next, a pulp sheet manufactured by Ino Paper Co., Ltd. with a basis weight of 50 g / m 2 was placed so as to cover the coating layer. After removing the water contained in the coating layer by heating, an aqueous electrolyte solution was uniformly sprayed onto the coating layer through the pulp sheet. Thereby, a sheet-like exothermic part was obtained. The composition of the exothermic layer in the sheet-like exothermic part was as shown in Table 1 below.

[0083] <Fabrication of Heating Appliance> A sheet-like exothermic part was sandwiched between a breathable first packaging material (air permeability: 4000 seconds / 100 mL, water vapor permeability: 1320 g / (m 2 ·24 h)) and a non-breathable second packaging material, and the peripheral regions of both packaging materials were heat-sealed to obtain a heating appliance in which the sheet-like exothermic part was accommodated in the packaging material. The first packaging material was arranged such that its inner surface faced the outer surface of the pulp sheet. Also, the second packaging material was arranged such that its inner surface faced the laminate paper. This heating device was formed to generate steam as it generates heat.

[0084] [Example 2] Instead of the purified cellulose powder used in Example 1, amorphous cellulose powder was used. Also, the composition of the heating layer in the sheet-like heating part was made as shown in Table 1. Otherwise, a heating device was obtained in the same manner as in Example 1. The amorphous cellulose powder had a cellulose content of 99%, a particle size of 70 μm, and a crystallinity of 0 to 10%.

[0085] [Examples 3 to 5] The composition of the heating layer in the sheet-like heating part was made as shown in Table 1. Otherwise, a heating device was obtained in the same manner as in Example 2.

[0086] [Example 6] The composition of the heating layer in the sheet-like heating part was made as shown in Table 2. Otherwise, a heating device was obtained in the same manner as in Example 1.

[0087] [Examples 7 and 8] In Example 3, a first packaging material having air permeability with an air permeability of 2500 seconds / 100 mL or an air permeability of 60 seconds / 100 mL was used. Otherwise, a heating device was obtained in the same manner as in Example 3.

[0088] [Example 9] In Example 2, instead of the laminated paper used in the production of the sheet-like heating part, crepe paper with a basis weight of 65 g / m 2 was used. Otherwise, a heating device was obtained in the same manner as in Example 2.

[0089] [Example 10] In Example 2, instead of the pulp sheet used in the production of the sheet-like heating part, a single water-absorbing resin-containing sheet having a structure in which a water-absorbing resin was sandwiched between two sheets of absorbent paper was used. The water-absorbent resin-containing sheet was produced by the method described in JP-A-8-246395. As the water-absorbent resin contained in the water-absorbent resin-containing sheet, particles of a crosslinked product of sodium polyacrylate were used. The basis weight of the water-absorbent resin was 70 g / m 2 It was. The basis weight of the absorbent paper was 50 g / m 2 It was.

[0090] [Comparative Examples 1 and 2] In Example 1, instead of using the purified cellulose powder, the composition of the heat-generating layer in the sheet-like heat-generating part was as shown in Table 1. Otherwise, a warming device was obtained in the same manner as in Example 1.

[0091] [Comparative Example 3] In Example 1, wood powder was used instead of the purified cellulose powder. Further, the composition of the heat-generating layer in the sheet-like heat-generating part was as shown in Table 1. Otherwise, a warming device was obtained in the same manner as in Example 1.

[0092] [Evaluation] Regarding the warming devices obtained in the examples and comparative examples, the heat generation characteristics (sensible heat integrated amount, 45°C arrival time, and water vapor generation amount) immediately after production and after storage at 50°C for 2 weeks were measured by the following methods. Also, the bending load peak before heat generation was measured by the following method. The results are shown in Tables 1 and 2.

[0093] [Sensible heat integrated amount] It was measured according to the following method in an environment of room temperature 20°C and humidity 50%RH. First, the warming device to be measured sealed and stored in an oxygen barrier bag was taken out by opening the oxygen barrier bag. Next, it was placed so that the first packaging material of the taken-out warming device faced outward, and a temperature sensor was installed and fixed on the surface of the second packaging material in the region where the heating element was arranged. The temperature sensor was fixed to the measurement surface with a mesh material (double raschel fabric made of polyester, thickness 8 mm) and a SUS plate (500 g perforated plate). The measuring instrument described in JIS S4100 was used with a temperature sensor connected thereto, and the temperature was measured over time. The temperature was measured at 10-second intervals with the time when the oxygen barrier bag was opened as the measurement start time, and the measurements were carried out for a total of 10 minutes, 20 minutes, and 30 minutes. From the heat generation profile plotted with the vertical axis being the measured temperature (°C) and the horizontal axis being the measurement time (seconds), at the time when a temperature of 35°C or higher was measured, the integrated value of the temperature obtained by subtracting 35°C from the measured temperature was calculated, and this was taken as the sensible heat integrated amount (°C·10 min, °C·20 min, or °C·30 min).

[0094] 〔Time to reach 45°C〕 In the measurement of the sensible heat integrated amount described above, the time until the temperature reached 45°C was measured, and this was taken as the time to reach 45°C.

[0095] 〔Water vapor generation amount〕 The water vapor generation amount was measured using the apparatus 100 shown in FIG. 8. First, the heat generating device to be measured hermetically stored in the oxygen barrier bag was taken out after opening the oxygen barrier bag. The heat generating device was placed in the measurement chamber 101 with the first packaging material of the taken-out heat generating device facing outward, and the weight 108 with a metal ball having a mass of 4.5 g attached thereto was placed thereon. In this state, dehumidified air was passed from the lower part of the measurement chamber 101, and the difference in absolute humidity before and after the air flow in the measurement chamber 101 was determined from the respective temperatures and humidities measured by the inlet temperature and humidity meter 104 and the outlet temperature and humidity meter 106. Further, based on the air flow rate measured by the inlet flow meter 105 and the outlet flow meter 107, the amount of water vapor generated from the heat generating device was calculated. With the time when the heat generating device was taken out from the oxygen barrier bag as the measurement start time, the total amount of water vapor measured in 10 minutes (mg·10 min), the total amount of water vapor measured in 20 minutes (mg·20 min), and the total amount of water vapor measured in 30 minutes (mg·30 min) were measured.

[0096] 〔Bending load peak〕 The bending load peak in the state before heat generation was measured using a tensilon testing machine (RTC-1150A manufactured by Orientec Co., Ltd.). The radius R of the indenter was 5 mm. Next, a heating part cut to a size of 49 mm × 49 mm was placed so as to span between both edges of a support base with an edge span of 15 mm. Then, under the conditions of a load range of 5 kgf / 20% and a descent speed of 50 mm / min, the indenter was lowered to obtain a load-deflection curve. The maximum value of the bending load obtained while the indenter was lowered by 11 mm was defined as the bending load peak [N]. The lower the value of the bending load peak, the higher the flexibility and the higher the fit of the heating device.

[0097]

Table 1

[0098]

Table 2

[0099] As is clear from the results shown in Table 1 and Table 2, it can be seen that the heating devices of each example provided with a heating layer containing purified cellulose are excellent in heating characteristics both before and after storage as compared with the heating devices of the comparative examples.

Explanation of Signs

[0100] 1 Heating device 3 Heating part 3a Powder of oxidizable metal 3b Powder of carbon material 3c Powder of purified cellulose 31, 32 Sheet 33 Heating layer 34 First packaging material 35 Second packaging material 36 Packaging material

Claims

1. The heat generating device has a sheet-like heat generating portion including a heat generating layer disposed between two sheets, at least one of which is a breathable sheet; The sheet-shaped heat generating part is configured to generate steam from the heat generating part as heat is generated, the heat generating layer contains an oxidizable metal powder, a carbon material powder, a refined cellulose powder, and water; A heating device, in which the mass ratio of the content of the refined cellulose powder to the content of the oxidizable metal powder is 0.005 or more and 0.35 or less.

2. The heating device according to claim 1, wherein the moisture content of the heat generating layer is 12% or more and 30% or less.

3. The heating device according to claim 1 or 2, wherein the bending load peak of the heating portion before heating is 1.5 N or less.

4. 4. The heating device according to claim 1, wherein the refined cellulose powder has a particle size of 10 μm or more and 200 μm or less.

5. A slurry containing a powder of an oxidizable metal, a powder of a carbon material, a powder of refined cellulose, and water is applied onto a first sheet to form a coating layer; A breathable second sheet is placed on the coating layer; removing water contained in the coating layer by heating; A method for producing a sheet-like heat generating part, comprising: supplying an aqueous electrolyte solution to the coating layer through a second sheet.

6. 6. The method for producing a sheet-like heating portion according to claim 5, wherein the mass ratio of the content of the mineral acid and its salt to the content of water in the heating portion is 0.04 or less.

Images