JP5025456B2 - Sheet heating element, sheet heating intermediate and heating sheet - Google Patents

Description

  The present invention relates to a sheet-like heating element that generates heat by reacting with oxygen in the air, a heating sheet, and a sheet-like heating intermediate.

  Regarding the sheet-like heating element that generates heat by reacting with oxygen in the air, the applicant has proposed the techniques of Patent Documents 1 and 2 below.

  The exothermic sheet described in Patent Document 1 has a maximum temperature by limiting the amount of moisture added to a sheet containing exothermic components such as iron powder and activated carbon, and the amount of oxygen supplied by the moisture-permeable sheet outside the exothermic sheet. Although it is possible to control in the direction of decreasing, it is difficult to control in the direction of increasing the maximum temperature.

  The exothermic sheet described in Patent Document 2 is such that a high exothermic temperature is instantly expressed at the time of use by reducing the particle size of activated carbon contained as an exothermic component. It was not something that could be maintained. Moreover, when manufacturing the exothermic sheet of patent document 2 by papermaking, since the particle size of activated carbon was small, it was difficult to remove water from a raw material composition, and manufacture was sometimes difficult.

JP 2004-202198 A JP 2005-224212 A

  An object of the present invention is to provide a sheet-like heating element, a sheet-like heating intermediate, and a heating sheet that can maintain a high heating temperature for a long time and are excellent in heating performance and production thereof.

  The present invention is a sheet in which activated carbon having an average particle size smaller than that of the activated carbon is arranged in a layer on at least one surface of an exothermic layer containing an oxidizable metal, a fibrous material, activated carbon, and an electrolyte that serves as an oxidation aid. The object is achieved by providing a heating element.

  Moreover, this invention provides the heat generating sheet by which the sheet-like heat generating body of the said invention is accommodated in the container which has moisture permeability.

  In addition, the present invention provides a layer of activated carbon having an average particle size smaller than that of the activated carbon on at least one side of the exothermic layer that includes an oxidizable metal, a fibrous material, and activated carbon, and does not include an electrolyte that serves as an oxidation aid. The sheet-like exothermic intermediate is provided.

  In the present invention, an exothermic composition containing an oxidizable metal, activated carbon, and an electrolyte that serves as an oxidation aid is accommodated in a moisture-permeable first container, and the activated carbon is disposed on at least one surface of the first container. By providing a heat generating sheet in which activated carbon having a smaller average particle diameter is arranged in layers, and the layered activated carbon and the first container are accommodated in a moisture-permeable second container, the object is achieved. Is achieved.

  According to the present invention, it is possible to provide a sheet-shaped heating element, a sheet-shaped heating intermediate, and a heating sheet that can maintain a high heat generation temperature for a long time and have excellent heat generation performance.

The present invention will be described below based on preferred embodiments with reference to the drawings.
FIG. 1 shows an embodiment of the present invention. In these drawings, reference numeral 1 denotes a heat generating sheet.

  As shown in FIG. 1, the heat generating sheet 1 of this embodiment is accommodated in a container 3 having a sheet-like heat generating element 2 having moisture permeability.

  In the sheet-like heating element 2, activated carbon having an average particle size smaller than that of the activated carbon is layered on at least one surface of the exothermic layer 21 containing an oxidizable metal, a fibrous material, activated carbon, and an electrolyte that serves as an oxidation aid. Has been. Hereinafter, the portion where the activated carbon is arranged in layers is also referred to as the activated carbon layer 22. The component with the highest ratio in the activated carbon layer is activated carbon, and components other than activated carbon (for example, a binder described later) may be present in the activated carbon layer. Further, “activated carbon is arranged in layers” means a state in which activated carbon is deposited on at least one surface of the exothermic layer, but does not necessarily have to be continuously deposited on the entire surface. The exothermic layer that does not contain an electrolyte that serves as an oxidation assistant is referred to as an exothermic intermediate layer, and the sheet-like heating element that does not contain an electrolyte that serves as an oxidation assistant is referred to as a sheet-like exothermic intermediate.

  The exothermic intermediate layer 21 preferably contains 50% by weight or more of components other than the fibrous material, more preferably 70% by weight or more, and further preferably 80% by weight or more. When the component other than the fibrous material is 50% by weight or more, the exothermic temperature can be sufficiently increased to the extent that it feels hot when touched with a human fingertip or the like. The more components other than the fibrous material, the better. However, the upper limit is 98% by weight from the viewpoint of obtaining the strength necessary to maintain the workability of the exothermic intermediate layer 21. Here, components other than the fibrous material are measured as follows.

Components other than the fibrous material in the exothermic intermediate layer 21 can be obtained from the following formula from the solid content weight in the raw material composition, the composition, and the dry weight of the exothermic intermediate layer 21.
Weight of raw material composition: Ms
Content of fibrous material in solid content of raw material composition: a (%)
Dry weight of exothermic intermediate layer: Mh
Content of components other than fibrous materials in the heat generation intermediate layer: b (%)
b = (Mh / Ms) × (100−a)

  As the oxidizable metal, an oxidizable metal conventionally used in this type of heat generating sheet can be used without any particular limitation. As the form of the oxidizable metal, it is preferable to use a form having a powdery or fibrous form from the viewpoint of handleability and moldability.

  Examples of the oxidizable metal having a powder form include iron powder, aluminum powder, zinc powder, manganese powder, magnesium powder, and calcium powder. Among these, handling property, safety, and manufacturing cost are included. Iron powder is preferably used. The oxidizable metal has a particle size (hereinafter referred to as the particle size, the maximum length in the form of powder, or dynamic light scattering because the fixability to a fibrous material and control of the reaction are good. The average particle diameter measured by a method, a laser diffraction method, etc.) is preferably 0.1 to 300 μm, and the one having a particle diameter of 0.1 to 150 μm and containing 50% by weight or more is used. It is more preferable.

  Examples of the oxidizable metal having a fibrous form include steel fibers, aluminum fibers, and magnesium fibers. Among these, steel fibers, aluminum fibers, and the like are preferably used from the viewpoints of handleability, safety, and manufacturing cost. As the oxidizable metal having a fibrous form, a fiber having a thickness of 0.1 to 50 mm and a thickness of 1 to 1000 μm should be used in terms of formability, mechanical strength of the obtained sheet, surface smoothness, and heat generation performance. Is preferred.

  The amount of the oxidizable metal in the exothermic intermediate layer 21 is preferably 10 to 95% by weight, and more preferably 30 to 80% by weight. When the blending amount is 10% by weight or more, the exothermic temperature of the exothermic layer can be sufficiently increased to the extent that a person feels hot by touching with a fingertip or the like. Moreover, the usage-amount of the below-mentioned fibrous material and adhesive components (coagulant | flocculant etc.) which form an exothermic layer can be suppressed, and it will become the thing excellent in the usability | use_condition from the point of hardness. When the blending amount is 95% by weight or less, the reaction sufficiently occurs to the inside of the exothermic layer, and the exothermic temperature can be made sufficient. In addition, the oxidizable metal expands due to the oxidation reaction and is hardened by condensation. The heat generation time can be sufficient, the water supply by activated carbon can be sufficient, and the oxidizable metal does not easily fall off. In addition, since a fibrous material and an adhesive component (such as an aggregating agent), which will be described later, constituting the sheet-like heating element are used to some extent, mechanical strength such as bending strength and tensile strength can be sufficiently ensured. Here, the blending amount of the oxidizable metal in the sheet-like heating element is obtained by an ash test according to JIS P8128. For example, in the case of iron, a vibration sample type is used by utilizing the property that magnetization occurs when an external magnetic field is applied. It can be quantified by a magnetization measurement test or the like.

  Examples of the activated carbon in the exothermic intermediate layer 21 include coconut shell charcoal, charcoal powder, calendar bituminous coal, peat, and lignite. The activated carbon preferably has an average particle size of 1 to 500 μm μm, more preferably 2 to 200 μm μm, from the viewpoint of forming an effective contact state with an oxidizable metal. The activated carbon may be in a form other than the powder form as described above, for example, a fibrous form such as activated carbon fiber may be used. In the present invention, the average particle diameter of the activated carbon is measured by a dynamic light scattering method, a laser diffraction method, or the like.

  The blending amount of the activated carbon in the exothermic intermediate layer 21 is preferably 0.5 to 60% by weight, and more preferably 1 to 50% by weight. When the blending amount is 0.5% by weight or more, sufficient water can be accumulated in the exothermic layer to sustain the reaction to such an extent that the oxidizable metal rises to a temperature higher than the human body temperature due to the oxidation reaction, Moreover, the air permeability of the exothermic layer can be made sufficient, oxygen supply is sufficient, and heat generation efficiency is excellent. When the blending amount is 60% by weight or less, the heat capacity of the exothermic layer with respect to the obtained calorific value can be suppressed, the heat generation temperature can be sufficiently increased, and the activated carbon hardly falls off. Since a fibrous material and an adhesive component described later that form the exothermic layer can be secured, mechanical strength such as bending strength and tensile strength can be secured.

  Examples of the fibrous materials include plant fibers (cotton, kabok, wood pulp, non-wood pulp, peanut protein fibers, corn protein fibers, soy protein fibers, mannan fibers, rubber fibers, hemp, Manila hemp Sisal, New Zealand hemp, Rafu hemp, eggplant, rush, straw, etc.), animal fibers (wool, goat hair, mohair, cashmere, alkapa, Angola, camel, vicuña, silk, feathers, down, feather, algin fiber, chitin Fiber, casein fiber, etc.) and mineral fiber (asbestos, etc.). Examples of synthetic fibers include semi-synthetic fibers (acetate, triacetate, oxide acetate, promix, chlorinated rubber, hydrochloric acid rubber, etc.), metal fibers , Carbon fiber, glass fiber and the like. Also, polyolefins such as high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene, etc., polyester, polyvinylidene chloride, starch, polyvinyl alcohol or polyvinyl acetate, single fibers such as copolymers or modified products thereof, or these A core-sheath composite fiber having a resin component in the sheath can be used. Among these, polyolefins and modified polyesters are preferably used because they have high adhesive strength between fibers, are easy to form a three-dimensional network structure by fusion of fibers, and have a melting point lower than the ignition point of pulp fibers. Synthetic fibers such as polyolefin having branches are also preferably used because of their good fixability to oxidizable metals and activated carbon. These fibers can be used alone or in combination of two or more. In addition, these fibers can be used in the form of collected and reused. Among these, wood pulp and cotton are preferably used from the viewpoints of the oxidizable metal, the fixability of the activated carbon, the flexibility of the resulting exothermic intermediate layer, the oxygen permeability resulting from the presence of voids, the production cost, etc. It is done.

  The fibrous material preferably has a CSF (Canadian Standard Freeness) of 600 ml or less, and more preferably 450 ml or less. When the amount is 600 ml or less, the fixing property between the fibrous material and the components such as the oxidizable metal and activated carbon is sufficient, a predetermined blending amount can be maintained, and the heat generation performance is excellent. In addition, a heat-generating layer having a uniform thickness is obtained, and the molded state is favorable, which is preferable. In addition, since the fixing property between the fibrous material and the component is sufficient, the component is unlikely to fall off, the entanglement between the component and the fibrous material, the bond strength derived from hydrogen bonding is sufficient, and the bending Mechanical strength such as strength and tensile strength can be sufficiently secured, and processability is excellent.

  The lower the CSF of the fibrous material, the better. However, when the ratio of components other than the fibrous material is low in the normal paper making of pulp fiber, the CSF is 100 ml or more, which is excellent in drainage and is dehydrated. It is preferable for obtaining a heat-generating layer having a uniform thickness. Also, blister breakage does not occur during drying, and good molding can be performed. In the present invention, when the ratio of components other than the fibrous material is high, an exothermic layer having good drainage and a uniform thickness can be obtained. Further, since the CSF is lower as the CSF is lower, the fixability between the fibrous material and components other than the fibrous material is improved, and a high sheet strength can be obtained. Adjustment of the CSF of the fibrous material can be performed by a beating process or the like. CSF may be adjusted by mixing low and high CSF fibers.

  The fibrous material preferably has a negative (negative) zeta potential. Here, the zeta potential is an apparent potential at the shear plane between the charged particle interface and the solution, and is measured by a streaming potential method, an electrophoresis method or the like. If the zeta potential is negative, the components such as the oxidizable metal and activated carbon are more favorably fixed to the fibrous material, the predetermined blending amount can be maintained, and the heat generation performance is sufficient. it can. In addition, a large amount of the component is not mixed in the waste water, there is no loss, and this is preferable in terms of productivity and environmental conservation.

  The fibrous material preferably has an average fiber length of 0.1 to 50 mm, and more preferably 0.2 to 20 mm. If the fiber length is too short, sufficient mechanical strength such as bending strength and tensile strength of the resulting exothermic layer cannot be secured, and the air permeability of the exothermic layer is impaired due to the dense formation of the fiber layer. Supply may be poor and heat generation may be inferior. If the fiber length is too long, it is difficult to uniformly disperse the fibrous material in the exothermic layer, and uniform mechanical strength cannot be obtained, and a uniform thick exothermic layer cannot be obtained. A space | interval becomes wide and the holding | maintenance capability of components, such as said oxidizable metal and activated carbon by a fiber, becomes low, and this component may fall off easily.

  The blending amount of the fibrous material in the exothermic intermediate layer 21 is preferably 2 to 50% by weight, and more preferably 5 to 40% by weight. When the blending amount is less than 2% by weight, the effect of preventing the components such as the oxidizable metal and activated carbon from falling off may be lowered, and the exothermic layer may be very brittle. When the blending amount exceeds 50% by weight, the heat capacity of the heat generating layer with respect to the heat generation amount increases, the temperature rise is reduced, and the ratio of the components in the resulting heat generating layer decreases, so that the desired heat generation performance is achieved. May not be obtained.

  A flocculant may be added to the exothermic intermediate layer 21 as described later. If necessary, the exothermic intermediate layer 21 includes additives usually used for paper making such as a sizing agent, a coloring agent, a paper strength enhancer, a yield improver, a filler, a thickener, a pH control agent, and a bulking agent. The product can be added without any particular limitation. The addition amount of the additive can be appropriately set according to the additive to be added.

  The thickness of the exothermic intermediate layer 21 is preferably 0.08 to 1.2 mm, and more preferably 0.1 to 0.6 mm. When the thickness is 0.08 mm or more, heat generation performance, mechanical strength, fixability of components such as the oxidizable metal and activated carbon are sufficient, and a stable and uniform thickness and composition distribution can be obtained. . In addition, it is difficult to cause sheet breakage due to pinholes and the like, which is preferable in terms of productivity and workability. When the thickness is 1.2 mm or less, the bending strength is excellent and the flexibility is high, and in particular, the wearability is excellent when worn on a body part such as an elbow, knee or face. In terms of productivity, the layer formation time and the drying time can be made relatively short, and the operability is excellent. Moreover, it is preferable also in terms of workability. Here, the thickness of the exothermic intermediate layer can be calculated according to JIS P8118 by measuring five or more points of the exothermic intermediate layer and calculating the average value as the thickness.

Pyrogenic intermediate layer 21 preferably has a basis weight of the first layer is 10 to 1000 g / m ^2, and more preferably 50~600g / m ^2. It is preferable that the basis weight is 10 g / m ² or more because a stable layer can be sufficiently formed even when an oxidizable metal having a high specific gravity is used. It is preferable that the basis weight is 1000 g / m ² or less because of excellent usability, productivity, operability and the like. The basis weight can be calculated by measuring the weight of the obtained exothermic intermediate layer 21 for an area of at least 100 cm ² and dividing by the area.

Pyrogenic intermediate layer 21 preferably has its density of 0.6~1.5g / cm ^3, more preferably 0.7~1.0g / cm ^3. When the density is 0.6 g / cm ³ or more, the oxidizable metal and the other components are sufficiently entangled, which is preferable in terms of strength. Further, when the density is 1.5 g / cm ³ or less, the air permeability of the molded article becomes sufficient, and the heat generation characteristics can be sufficiently exhibited. The density can be calculated by dividing the basis weight of the exothermic intermediate layer 21 by its thickness.

The exothermic intermediate layer 21 preferably has a breaking length of 100 to 4000 m, and more preferably 200 to 3000 m. When the breaking length is 100 m or more, a layer can be formed sufficiently stably during operation, and product processing can be preferably performed during processing. Further, even during use, it can have sufficient strength and excellent usability. When the breaking length is 4000 m or less, the amount of fibrous materials and adhesive components constituting the exothermic intermediate layer 21 can be suppressed, and the flexibility can be enhanced and the exothermic performance can be improved. Here, the tearing length is determined by cutting a test piece of length 150 mm × width 15 mm from the exothermic intermediate layer 21 and then mounting the test piece on a tensile tester with a chuck interval of 100 mm according to JIS P8113. A tensile test is performed at 20 mm / min, and the value is calculated by the following formula.
Breaking length [m] = (1 / 9.8) × (Tensile strength [N / m]) × 10 ⁶ / (Test piece basis weight [g / m ² ])

  Examples of the activated carbon used for the activated carbon layer 22 include coconut shell charcoal, charcoal powder, calendar bituminous coal, peat, lignite, and the like, as in the activated carbon used in the exothermic intermediate layer. The average particle diameter Rs of the activated carbon used for the activated carbon layer 22 is preferably 0.1 to 100 μm, from the viewpoint of improving the heat generation characteristics of the heating element and forming a uniform layer, and 0.5 to 50 μm. It is more preferable that

  The ratio Rs / Rc of the average particle diameter of the activated carbon used for the exothermic intermediate layer (exothermic layer) 21 and the activated carbon layer 22 is preferably 0.01 to 0.7, and 0.05 to 0.5. It is more preferable that When the ratio is within such a range, significant exothermic improvement can be obtained.

The amount of the activated carbon in the activated carbon layer 22 is determined by the required heat generation performance. The amount of the activated carbon in the activated carbon layer 22 is preferably 0.1 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the solid content of the molded sheet (exothermic intermediate layer) raw material composition described later. preferable. Moreover, 0.1-100 g / m < ² > is preferable and the basic weight of an activated carbon layer has more preferable 1-50 g / m < ² >. When the blending amount and basis weight of the activated carbon in the activated carbon layer 22 are within such ranges, in addition to improving the heat generation performance, it is possible to suppress the falling off of the activated carbon.

  The activated carbon layer 22 can contain other components such as a binder, a water retention agent, a filler, and a fragrance in addition to the activated carbon as described above. The blending amount of these components is determined according to the required heat generation performance.

  Examples of binders to be included in the activated carbon layer 22 include water-soluble polymers such as carboxymethyl cellulose, starch, sodium alginate, polyvinyl alcohol, and polyethylene glycol, acrylic resins such as methacrylic acid esters and acrylic acid esters, polyolefins such as polyethylene and polypropylene, and polyesters. And thermoplastic resins such as polyurethane, and inorganic binders such as colloidal silica and colloidal alumina. Examples of the water retention agent contained in the activated carbon layer 22 include water-absorbing polymer, wood powder, carbon black, acetylene black, graphite, zeolite, perlite, vermiculite, silica, cancrinite, and fluorite.

  As the electrolyte serving as the oxidation aid contained in the sheet-like heating element 2, an electrolyte that has been conventionally used for this kind of heating element can be used without particular limitation. Examples of the electrolyte include alkali metal, alkaline earth metal or heavy metal sulfates, carbonates, chlorides or hydroxides. Among these, various chlorides such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, ferrous chloride, and ferric chloride are preferably used from the viewpoint of excellent conductivity, chemical stability, and production cost. These electrolytes can be used alone or in combination of two or more.

  The amount of the electrolyte serving as the oxidation aid in the sheet-like heating element 2 is preferably 0.5 to 30% by weight, and preferably 1 to 25% by weight, in terms of the weight ratio of water in the sheet-like heating element 2. It is more preferable. When the blending amount is 0.5% by weight or more, the oxidation reaction of the obtained sheet-like heating element can be made sufficient, and the heating temperature rise can be made sufficient. When the blending amount is 30% by weight or less, the air permeability of the sheet-like heating element can be made good, and the heat generation performance is excellent by supplying sufficient water to the oxidizable metal or the like. Can be. Moreover, it is preferable at the point which can mix | blend the electrolyte used as an oxidation adjuvant uniformly with a sheet-like heat generating body.

  The sheet-like heating element 2 preferably has a thickness of 0.08 to 1.2 mm, more preferably 0.1 to 0.6 mm. When the thickness is within such a range, heat generation performance, mechanical strength, iron powder, activated carbon, and other components can be well fixed, and a stable and uniform thickness and composition distribution can be obtained. Here, the thickness of the sheet-like heating element 2 can be calculated as the thickness by measuring five or more points of the molded sheet according to JIS P8118.

Sheet-like heating element 2 is preferably a basis weight of one that is 10 to 2000 g / m ^2, and more preferably 50 to 1500 g / m ^2. When the basis weight is within such a range, it is light and excellent in feeling of use, and is preferable in terms of productivity and operability.

The sheet heating element 2 preferably has an exothermic temperature of 30 to 100 ° C, and more preferably 35 to 90 ° C. Here, the heat generation reached temperature is 5000 g of moisture permeability (hereinafter simply referred to as moisture permeability) measured on the heat generating sheet by JIS Z208 after cutting out a 50 mm × 50 mm test piece from the heat generating sheet. / (M ² · 24h) Moisture-permeable sheet and moisture-impermeable sheet are attached to both sides in a bag shape and packaged, and then placed in a sealed system under an environment with a volume of 4.2 liters and a relative humidity of 1% or less. Prepare a tester capable of supplying 0.0 liter / min of dry air, and set the moisture permeable sheet side as the upper surface in the tester to generate heat. It is a measured value. The heat generation ultimate temperature of the sheet-like heating element can be arbitrarily designed depending on the combination of the above-described blending compositions, such as a case where a rapid heat generation is required depending on the product use, or a product which requires a relatively low temperature and a long time.

Sheet-like heating element 2, the amount of water vapor generated in 10 min per unit area is preferably ^{1~100mg / (cm 2 · 10min)} , and more to be 1~50mg / (cm ² · 10min) preferable. Here, the water vapor amount is measured as follows.

Prepare a tester with a volume of 4.2 liters and a humidity of 1 RH% or less and capable of supplying 2.0 liters / min of dry air in a closed system, and place the sheet in the interior so that water vapor can evaporate. Heat. And the humidity of the air discharged | emitted in the said closed system was assumed with the hygrometer, the amount of water vapor | steam generated after the start of heat_generation | fever was calculated | required using following formula (1), and it was set as the amount of water vapor | steam per unit time. And the cumulative value for 10 minutes was calculated | required as a steam generation amount, and converted per unit area. Here, e is a water vapor pressure (Pa), es is a saturated water vapor pressure (Pa: quoted from JIS Z8806), T is a temperature (° C .: dry bulb temperature), and s is a sampling period (seconds).
Relative humidity U (% RH) = (e / es) × 100
Absolute humidity D (g / m ³ ) = (0.794 × 10 ⁻² × e) / (1 + 0.00366T)
= (0.794 × 10 ^-2 × U × es) / [100 × (1 + 0.00366T)]
Unit air volume P (liter) = (2 × s) / 60
Amount of water vapor per unit time A (g) = (P × D) / 1000 (1)

  The amount of water vapor can be arbitrarily designed depending on the combination of the above-mentioned blending compositions, such as when a rapid heat generation is required depending on the product application, as well as the heat generation arrival time, or a product that needs to be maintained at a relatively low temperature for a long time.

  The sheet-like heating element 2 has a moisture content (weight moisture content, the same shall apply hereinafter) of preferably 10 to 80%, and more preferably 20 to 60%. When the moisture content is within such a range, the heat capacity with respect to the heat generation amount does not increase, and the heat generation temperature rises sufficiently.

The container 3 only needs to have moisture permeability and can prevent the components of the sheet-like heating element from falling off. However, in order to obtain sufficient heat generation characteristics of the sheet-like heating element 2, moisture permeability is sufficient. ^{100~10000g / (m 2 · 24h)} , it is particularly preferably ^{1000~8000g / (m 2 · 24h)} . The entire surface of the container 3 may be air permeable or partially air permeable.

  It is preferable to provide the breathable portion of the container 3 on the surface on which the activated carbon layer 22 is formed. As a result, the presence of the oxidizable metal, oxygen, and activated carbon in the proximity positions promotes the oxidation reaction and provides good heat generation characteristics.

  In the heat generating sheet 1 of the present embodiment, the container 3 is provided by bonding a breathable sheet 31 and a non-breathable sheet 32 with a joint portion 30 having a predetermined width so as to cover the sheet-shaped heat generating element.

Breathable sheet 31 is not particularly limited as long as a sheet having air permeability, moisture permeability ^{100~10000g / (m 2 · 24h)} , it is preferable in particular 1000~8000g / (m ² · 24h) . When the moisture permeability is in this range, heat and water vapor are immediately generated as soon as the heating tool is taken out of the packaging material, and you can feel the warmth and humidity without waiting for it to warm up. The high penetration effect of the functional agent can be obtained. The air permeable sheet 31 may have air permeability over the entire surface, or may partially have air permeability.

Breathable sheet 31 is preferably a basis weight of 10 to 200, in particular 20 to 100 g / m ^2. When the basis weight of the air-permeable sheet 31 is in such a range, it is thin, flexible, and very comfortable to touch, and does not impair the softness of the heat generating sheet 1, and can generate quick heat and water vapor. it can.

  As the breathable sheet 31, holes were mechanically formed in a sheet made of a resin such as polyolefin such as polyethylene (PE) or polypropylene (PP), polyester, polyamide, polyurethane, polystyrene, polyethylene-vinyl acetate copolymer, or the like. Or a mixture sheet of the above resin and inorganic filler that has undergone interfacial exfoliation to provide micropores, that uses interfacial exfoliation of its crystal structure to form micropores, and uses open cells by foam molding In addition, there may be mentioned those in which micropores are communicated. Further, synthetic pulp such as polyolefin, semi-synthetic fiber such as wood pulp, rayon and acetate, non-woven fabric, woven fabric, synthetic paper, paper and the like formed from vinylon fiber, polyester fiber, and the like are also included. A plurality of breathable sheets 31 can be used in a stacked manner.

The non-breathable sheet 32 is not particularly limited as long as it is a non-breathable sheet, but the moisture permeability may be 10 g / (m ² · 24 h) or less, particularly 1.0 g / (m ² · 24 h) or less. preferable. If the moisture permeability is in such a range, the direction of water vapor generation accompanying heat generation can be partially restricted. Thereby, in the heat generating sheet 1, oxygen is supplied from the air-permeable sheet side, generation of water vapor can be suppressed from the non-air-permeable sheet surface, and water vapor can be generated only from the air-permeable sheet side.

The non-breathable sheet 32 preferably has a basis weight of 10 to 200 g / m ² , particularly 20 to 100 g / m ² . When the basis weight of the non-breathable sheet 32 is within such a range, the softness and flexibility of the heating tool can be maintained, and the concealability of the heating element can be improved.

  Examples of the non-breathable sheet 32 include sheets made of resins such as polyolefins such as PE and PP, polyesters, polyamides, polyurethanes, polystyrenes, nylons, polyvinylidene chlorides, and polyethylene-vinyl acetate copolymers. When concealability is required, a sheet in which an inorganic filler such as titanium oxide is blended in the resin is used. A plurality of non-breathable sheets 32 can be used in a stacked manner.

  The exothermic sheet 1 is provided by being wrapped in an oxygen-impermeable packaging material when not in use.

  In the heat generating sheet 1, for example, a sheet heating element manufactured as described below is disposed at a predetermined position between the breathable sheet 31 and the non-breathable sheet 32 constituting the container 3, and the sheet heating element 2 is disposed. After the breathable sheet 31 and the non-breathable sheet 32 are joined so as to be sealed, they are manufactured by cutting into a predetermined shape.

  When manufacturing a sheet-shaped heating element, first, a raw material composition (slurry) containing the oxidizable metal, the activated carbon, the fibrous material, and water is prepared, and a molded sheet to be the exothermic intermediate layer is produced. To do. Then, the produced exothermic intermediate layer includes a liquid containing activated carbon used for the activated carbon layer 22 and an electrolyte that serves as the oxidation aid to form an activated carbon layer and include an electrolyte that serves as the oxidation aid. To produce a desired sheet-like heating element.

The flocculant is preferably added to the raw material composition. Examples of the flocculant include inorganic flocculants composed of metal salts such as sulfate band, polyaluminum chloride, ferric chloride, polyferric sulfate, and ferrous sulfate; polyacrylamide, sodium polyacrylate, polyacrylamide Mannich modified products, poly (meth) acrylic acid aminoalkyl ester-based, carboxymethylcellulose sodium-based, chitosan-based, starch-based, polyamide epichlorohydrin-based polymer flocculants; dimethyldiallylammonium chloride-based or ethyleneimine-based Organic coagulants such as condensates of alkylene dichloride and polyalkylene polyamines, dicyandiamide / formalin condensates; clay minerals such as montmorillonite and bentonite; silicon dioxide such as colloidal silica or hydrates thereof; hydrous magnesium silicate such as talc And the like. Of these flocculants, anionic colloidal silica, bentonite, and the like are cationic in terms of sheet surface properties, texture formation, moldability improvement, fixing rate of components such as oxidizable metals and activated carbon, and paper strength. Of these, starch, polyacrylamide, and the like, and anionic carboxymethylcellulose sodium salt and cationic polyamide epichlorohydrin cationic and anionic drugs are particularly preferred. Besides these combinations, these flocculants may be used alone or in combination of two or more.

  The amount of the flocculant added is preferably 0.01 to 5% by weight, more preferably 0.05 to 1% by weight, based on the solid content of the raw material composition. When the content is 0.01% by weight or more, the agglomeration effect is excellent, the oxidizable metal, activated carbon and other components can be prevented from falling off during papermaking, and the raw material composition can be made uniform, It is excellent in that a molded sheet having a uniform thickness and composition can be obtained. When the added amount is 5% by weight or less, the flocculant is difficult to stick to the drying roll during drying, the productivity is excellent, the potential balance of the raw material composition is stable, and the above components to white water during papermaking It is excellent in that the amount of falling off can be reduced. Further, the progress of the oxidation reaction of the molded sheet can be suppressed, and the storage stability such as heat generation characteristics and strength is excellent.

  The concentration of the raw material composition is preferably 0.05 to 10% by weight, and more preferably 0.1 to 2% by weight. When the concentration is 0.05% by weight or more, a large amount of water is not used, and the time required for forming the formed sheet can be shortened. Moreover, it is possible to sufficiently form a sheet having a uniform thickness. When the concentration is 10% by weight or less, the dispersibility of the raw material composition is good, the surface property of the obtained sheet is excellent, and a sheet having a uniform thickness is obtained.

Next, the raw material composition is paper-made to form the molded sheet.
Examples of the paper making method of the molded sheet include a continuous paper making type circular paper machine, a long paper machine, a short paper machine, a twin wire paper machine, and a batch type paper making method. For example, there is a cocoon method. Furthermore, a molded sheet can also be formed by multilayer lamination using the raw material composition and a composition having a composition different from the raw material composition. In addition, the molded sheets obtained by papermaking the raw material composition are laminated in multiple layers, or a sheet-like material obtained from a composition having a composition different from the raw material composition is laminated to the molded sheet. A molded sheet can also be formed.

  The molded sheet can be dehydrated until the moisture content (weight moisture content, the same shall apply hereinafter) is 70% or less from the viewpoint of maintaining the form after papermaking (shape retention) and maintaining mechanical strength. Preferably, it is more preferable to dehydrate to 60% or less. Examples of the method for dewatering the molded sheet after papermaking include dewatering by suction, a method of dehydrating by blowing pressurized air, a method of dehydrating by pressing with a pressure roll or a pressure plate, and the like.

  The molded sheet containing the oxidizable metal is actively dried to separate moisture, thereby obtaining a molded sheet excellent in suppressing oxidation of the oxidizable metal during the production process and excellent in long-term storage stability. Is possible. Furthermore, in addition to the point of increasing the supporting force of the oxidizable metal to the fibrous material after drying and suppressing its falling off, from the point of expectation of improvement in mechanical strength due to the addition of a hot melt component and a thermal crosslinking component, It is preferable to dry the molded sheet after making the molded sheet and before containing an electrolytic solution of an electrolyte serving as the oxidation aid.

  The molded sheet is preferably dried by heat drying. In this case, the heat drying temperature is preferably 60 to 300 ° C, more preferably 80 to 250 ° C. If the heating and drying temperature of the molded sheet is too low, the drying time becomes longer, so that the oxidation reaction of the oxidizable metal is promoted along with the drying of moisture, which may cause a decrease in the heat generation of the heating sheet, Only the front and back layers of the heat generating sheet promote the oxidation reaction of the oxidizable metal and may turn light brown. When the heating and drying temperature is too high, the performance of activated carbon or the like is deteriorated, the heat generation effect of the heat generating sheet is reduced, and the structure of the molded sheet may be destroyed due to a rapid evaporation of moisture inside the molded sheet.

  The moisture content of the molded sheet (exothermic intermediate layer) after drying is preferably 20% or less, and more preferably 10% or less. When the moisture content is 20% or less, excellent long-term storage stability, for example, even when temporarily stored in a wound roll state, moisture does not easily move in the thickness direction of the roll, heat generation performance, mechanical It is excellent in that it can supply a uniform product in strength.

  The drying method of the molded sheet can be appropriately selected according to the thickness of the molded sheet, the processing method of the molded sheet before drying, the moisture content before drying, the moisture content after drying, and the like. Examples of the drying method include drying methods such as contact with a heating structure (heating element), spraying of heated air or steam (superheated steam), vacuum drying, electromagnetic wave heating, and electric heating. Moreover, it can also implement simultaneously with the above-mentioned dehydration method.

  The molding (dehydration and drying) of the molded sheet is preferably performed in an inert gas atmosphere. However, as described above, the molded sheet does not contain an electrolyte that serves as an oxidizing aid. Molding can also be performed in an air atmosphere. For this reason, manufacturing equipment can be simplified. Further, if necessary, it is possible to perform creping, slitting, trimming, and processing such as changing the form by processing. Since the obtained molded sheet is thin and difficult to break, it can be rolled up as necessary. In addition, by forming the molded sheet alone or in layers or with other sheets such as paper, cloth (woven fabric or non-woven fabric), film, and pressurizing, further pressurizing and embossing or needle punching, A plurality of sheets can be laminated and integrated, and uneven forming and punching can also be performed. Moreover, by making the raw material composition contain a thermoplastic resin component or a hot water decomposing component, it is possible to perform heat sealing and facilitate bonding.

  Next, the activated carbon layer 22 is formed on the surface of the molded sheet (exothermic intermediate layer). The activated carbon layer 22 can also be formed by including a component contained in the activated carbon layer 22 and a liquid containing an electrolyte serving as the oxidation aid from one side of the molded sheet. The step of containing this liquid is preferably performed in an atmosphere of an inert gas such as nitrogen or argon. However, when an electrolyte serving as an oxidation aid is added by impregnation of the electrolytic solution, an oxidation reaction immediately after the addition is performed. Since it is mild, an electrolyte that serves as the oxidation aid can be contained in a normal air atmosphere.

  The method of adding the liquid to the molded sheet can be appropriately set according to the processing method, moisture content, form, and the like of the molded sheet after papermaking. As a method for containing the liquid, a method in which the molded sheet is impregnated with an electrolyte solution having a predetermined concentration of the electrolyte serving as the oxidation assistant, and an electrolyte having the predetermined particle diameter of the electrolyte serving as the oxidation assistant is added as a solid. Then, a method such as a method of containing in a molded sheet can be mentioned. Among these, a method of impregnating an electrolyte solution of a predetermined concentration is preferable from the viewpoint that the molded sheet can uniformly contain an electrolyte as an oxidation aid and that the moisture content can be adjusted simultaneously.

  The sheet-like heating element 2 can also be produced by preparing a sheet-like heating element (sheet-like heating intermediate) that does not contain an electrolyte that serves as an oxidation aid and then including an electrolyte that serves as an oxidation aid. In this case, it can also be produced by forming the activated carbon layer after including a liquid containing only the components of the activated carbon layer on one surface of the exothermic intermediate layer, and then including an electrolyte that serves as an oxidation aid. .

  As described above, the molded sheet (exothermic layer 21) contains an electrolyte serving as an oxidizing aid, and after the activated carbon layer 22 is formed, the moisture content is adjusted and stabilized as necessary to obtain a sheet-like heating element. 2 can be used. Then, if necessary, it can be processed into a predetermined size by performing processing such as trimming, lamination of two or more sheets, and the like. And as above-mentioned, the heat_generation | fever sheet | seat 1 can be manufactured by accommodating in the accommodating body 3. FIG.

As described above, the heat generating sheet 1 according to the present embodiment has a layer of activated carbon having an average particle size smaller than the average particle size of the activated carbon included in the heat generating layer 21 on the surface of the heat generating layer 21. Therefore, compared to the case of only the exothermic layer 21, it is possible to obtain a heat generating sheet having excellent heat generation characteristics such as an increase in temperature rise, an increase in heat generation temperature, and an improvement in long-term durability at a high temperature.
In addition, since an exothermic intermediate layer containing activated carbon having a large average particle diameter is formed and an activated carbon layer containing activated carbon having a small average particle diameter is formed on the surface thereof, it is possible to prevent a decrease in drainage during papermaking, Papermaking is easy and the subsequent dehydration drying process can be shortened. Therefore, it is possible to manufacture without reducing the production efficiency in improving the performance.
Moreover, the heat generating sheet 1 of this embodiment is thin, excellent in flexibility, and has a good touch during use. Moreover, the heat generating sheet 1 of the present embodiment can be applied to various uses by combining the functions of heating and water vapor generation and the functions of the various functional agents. For example, as a heat pack combined with a pack agent, skin care applications such as moisturizing and wrinkle removal, and as a hot pap combined with a distribution agent (heat distribution), also apply to health care applications such as relief of hand pain. Can do.

  In particular, the function of the functional agent can be further enhanced by causing the functional agent on the non-breathable sheet 32 side to function on the target after water vapor generated from the breathable sheet 31 side is applied to the target. For example, the effect of the pack agent can be further enhanced by applying a pack agent as a functional agent after expanding the pores by applying water vapor to the skin. Alternatively, it is also possible to make the cleaning agent as a functional agent function more effectively after softening dirt with water vapor.

Next, another embodiment of the heat generating sheet of the present invention will be described.
In the heat generating sheet of this embodiment, an exothermic composition containing an oxidizable metal, activated carbon, and an electrolyte serving as an oxidation aid is stored in a moisture-permeable first container, and at least one surface of the first container. Further, an activated carbon layer having an average particle size smaller than that of the activated carbon is disposed, and the activated carbon layer and the first container are accommodated in a moisture permeable second container. The exothermic composition (exothermic component) in the exothermic sheet of this embodiment has the same composition as the exothermic intermediate layer in the exothermic sheet of the above embodiment except that the fibrous material is not included.

  In the exothermic sheet of this embodiment, the relationship between the average particle diameter Rc of the activated carbon contained in the exothermic composition, the average particle diameter Rs of the activated carbon arranged in a layered manner, and the ratio Rs / Rc thereof is the same as that of the above embodiment. Same as the heat generating sheet.

  The sheet used for the first container and the second container is also the same sheet as the container 3 in the above embodiment. In this case, as in the above embodiment, a breathable sheet is disposed on the side where the activated carbon layer is disposed.

  The heat generating sheet of the present embodiment is similar to the heat generating sheet of the above embodiment in that the temperature rise is improved, the heat generation temperature is improved, and the long-term sustainability of the high temperature is improved as compared with the case of only the heat generating composition. Thus, a heat generation sheet having excellent heat generation characteristics can be obtained.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

  In the heat generating sheet of the present invention, like the heat generating sheet 1 of the above-described embodiment, it is preferable that the sheet-like heating element 2 contains an electrolytic electrolyte solution as an oxidation aid in advance. It is also possible to produce a heat generating sheet without including an electrolytic solution of an electrolyte serving as an oxidation aid and to include the electrolytic solution of an electrolyte serving as the oxidation aid during use. In this way, when an electrolyte that serves as an oxidation aid is not included, it is not necessary to carry out the production in an oxygen-free or low-oxygen atmosphere, so that the production process and production equipment can be simplified. be able to.

  The form of the heat generating sheet of the present invention can be appropriately changed according to the application. For example, when the heat generating sheet is used by being wrapped around a body or an object, it can be formed in a band shape. Moreover, when using it on the surface of a body or a target object, it can also be set as a form like a cloth.

  In the heat generating sheet of the present invention, the layer structure of the sheet-shaped heat generating element and the container can be changed according to the application. For example, as in the above-described embodiment, the activated carbon layer is provided on one side of the exothermic layer in the sheet-like heating element, and air permeability is imparted only to the activated carbon layer side of the container, but both sides of the exothermic layer in the sheet-like heating element are provided. An activated carbon layer can be provided on the container, and in accordance with this, the container can be formed by joining two breathable sheets.

  In the above embodiment, the breathable sheet and the non-breathable sheet are bonded by heat sealing. However, for these sealing and bonding methods, other methods such as a method using an adhesive are employed. You can also.

  The use of the heat generating sheet of the present invention is not particularly limited, but as a hot sheet in combination with various functional agents such as cleaning / disinfecting, sustained release of wax, aroma, and deodorization, in addition to the use in the above embodiment. , Flooring, folding, around the range, house care use such as ventilation fans, air care use to make the space comfortable, car care use such as car washing, waxing, face, body washing, disinfection, moisturizing, makeup removal, etc. It is also suitable for skin care applications, bedding applications such as futons, blankets or their covers, and rug applications such as cushions and leisure sheets.

  Hereinafter, the present invention will be described in more detail with reference to examples. The scope of the present invention is not limited to such examples.

  Exothermic sheets were produced as in the following examples and comparative examples, and the exothermic characteristics and water vapor generation characteristics of the obtained exothermic sheets were evaluated as follows.

[Example 1]
<Preparation of raw material composition for exothermic layer>
Oxidizable metal: Iron powder, manufactured by Dowa Mining Co., Ltd., trade name “RKH”, 83% by mass
Fibrous material: Pulp fiber (made by Fletcher Challenge Canada Co., Ltd., trade name “Machenzie” CSF 150 ml) 8% by mass
Activated carbon: manufactured by Nippon Enviro Chemicals Co., Ltd., trade name “Carborafine”, average particle size 45 μm, 9% by mass
Flocculant: 0.22 parts by weight of sodium carboxymethylcellulose (Daiichi Kogyo Seiyaku Co., Ltd., trade name “Serogen HE1500F”) and polyamide for a total of 100 parts by weight of the oxidizable metal, fibrous material and activated carbon Epichlorohydrin resin (manufactured by Nippon PMC Co., Ltd., trade name “WS4020”) 0.8 part by weight Water: Add industrial water until solid content concentration becomes 0.3 mass%

<Paper making process>
Using the raw material composition, a wet exothermic intermediate layer (molded sheet) was obtained using a hand machine according to JIS P8209.

<Dehydration and drying process>
The wet exothermic intermediate layer thus obtained was dried with a drying roll at 140 ° C. according to JIS P8209 to obtain an exothermic intermediate layer having a water content of 2% by mass or less. The basis weight of the resulting exothermic intermediate was 400 g / m ² .

<Production process of sheet heating element>
Cut the above exothermic intermediate into 50 × 50 mm squares, prepare a liquid containing the following activated carbon and electrolyte as an oxidation aid, spray onto the surface of the above exothermic intermediate layer, and impregnate the sheet-like heating element. Produced. In the obtained sheet-like heating element, a layer in which the following activated carbon was uniformly dispersed was formed on the sheet surface.
Composition of liquid: 0.34 g of 5% sodium chloride aqueous solution containing 0.022 g of the following activated carbon
Activated carbon: manufactured by Futamura Chemical Co., Ltd., trade name “SA1000”, average particle size 9 μm
Ratio Rs / Rc: 0.2

<Process for producing heat generating sheet>
The sheet-like heating element obtained as described above was housed in a container made of a breathable sheet on both the front and back surfaces and sealed by heat sealing to obtain a heating sheet.
Top sheet: Polypropylene spunbonded nonwoven fabric (basis weight 20 g / m ² )
Breathable sheet: polyethylene microporous sheet, air permeability of 10,000 seconds

<Evaluation of heat generation characteristics>
A tester capable of supplying 2.0 liter / min of dry air in a closed system with a volume of 4.2 liters and a humidity of 1 RH% or less is prepared. To heat. And the temperature of the heat generating sheet lower part was measured with the thermocouple, and the elapsed time-temperature graph of the heat generating sheet was obtained. And the maximum value of temperature was defined as the maximum temperature from the elapsed time-temperature graph of the obtained heat generating sheet. Moreover, the temperature integration value of the part in which the heat generating sheet showed 30 ° C. or more was obtained from the time when the temperature was 30 ° C. or more and the following formula, and evaluated as an index of the amount of heat generation.

<Water vapor generation characteristics>
When evaluating the heat generation characteristics, the temperature and humidity of the discharged air were measured, the amount of water vapor generated after the start of heat generation was determined using the following formula (2), and the amount of water vapor per unit time was obtained. And the accumulation value for 30 minutes was calculated | required as a steam generation amount, and it converted per unit area. Here, e is a water vapor pressure (Pa), es is a saturated water vapor pressure (Pa: quoted from JIS Z8806), T is a temperature (° C .: dry bulb temperature), and s is a sampling period (seconds).
Relative humidity U (% RH) = (e / es) × 100
Absolute humidity D (g / m ³ ) = (0.794 × 10 ⁻² × e) / (1 + 0.00366T)
= (0.794 × 10 ^-2 × U × es) / [100 × (1 + 0.00366T)]
Unit air volume P (liter) = (2 x s) / 60
Amount of water vapor per unit time A (g) = (P × D) / 1000 (2)

[Comparative Example 1]
A heating sheet was produced in the same manner as in Example 1 except that the activated carbon layer was not formed.

[Comparative Example 2]
A heating sheet was prepared in the same manner as in Example 1 except that the activated carbon layer was formed of activated carbon having the same average particle diameter as that of the activated carbon used for the exothermic layer. Ratio Rs / Rc: 1

〔Results and discussion〕
As shown in Table 1 and FIG. 2, it was confirmed that the exothermic sheet of the example showed higher values than those of the comparative example in the maximum temperature, the calorific value, and the water vapor generation amount.

FIG. 1 is a schematic view showing a cross section of an embodiment of the heat generating sheet of the present invention. FIG. 2 is a diagram illustrating the heat generation characteristics of the heat generation sheets obtained by the examples and the comparative examples.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat generating sheet 2 Sheet-like heating element 21 Heat generating layer 22 Activated carbon layer 3 Container

Claims (6)

  A sheet-like heating element in which activated carbon having an average particle size smaller than that of the activated carbon is arranged in layers on at least one surface of an exothermic layer containing an oxidizable metal, a fibrous material, activated carbon, and an electrolyte serving as an oxidation aid.   The average particle diameter Rc of the activated carbon contained in the exothermic layer is 1 to 500 μm, the average particle diameter Rs of the activated carbon arranged in the layered form is 0.1 to 100 μm, and the ratio Rs / Rc is 0.01. It is -0.7, The sheet-like heat generating body of Claim 1.   A heating sheet in which the sheet-like heating element according to claim 1 is accommodated in a moisture-permeable accommodating body.   Sheet-like heat generation in which activated carbon having an average particle size smaller than that of the activated carbon is arranged in layers on at least one surface of the exothermic layer that includes an oxidizable metal, a fibrous material, and activated carbon, and does not include an electrolyte that serves as an oxidation aid. Intermediates.   An exothermic composition containing an oxidizable metal, activated carbon, and an electrolyte that serves as an oxidation aid is contained in a moisture-permeable first container, and an average particle diameter is larger than that of the activated carbon on at least one surface of the first container. A heat generating sheet in which small activated carbon is arranged in layers, and the layered activated carbon and the first container are accommodated in a moisture-permeable second container.   The activated carbon contained in the exothermic composition has an average particle diameter Rc of 1 to 500 μm, an average particle diameter Rs of the activated carbon arranged in a layered form is 0.1 to 100 μm, and a ratio Rs / Rc of 0.01 The heat generating sheet according to claim 5, which is ˜0.7.

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