JP2005224314A - Sheet formed heating body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin sheet formed heating body with excellent heating characteristics. <P>SOLUTION: The sheet formed heating body comprises a heating sheet, an intermediate heating sheet including an oxidized metal, a water holding agent and a fibrous material, impregnated with electrolyte and water, and an air-permeable sheet disposed on one side or both sides of the heating sheet. The intermediate heating sheet has a basis weight of 10-1,000 g/m<SP>2</SP>per a sheet and the content of the water retaining agent is 3-60% by weight. The water vapor permeability of the air permeable sheet is 100-10,000 g/(m<SP>2</SP>× 24h). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet-like exothermic molded body using heat generated by an oxidation reaction between oxygen in air and an oxidizable metal.

  The present applicant has previously proposed a thin heat generating sheet described in Patent Document 1 below, which relates to a heat generating sheet using heat generated by an oxidation reaction between oxygen in the air and an oxidizable metal. The heat generating sheet has excellent heat generation characteristics as a heat generating element despite its extremely small thickness, and is excellent in productivity. Further, it is characterized in that the constituent components are less dropped from the sheet as compared with a heating element using a conventional powder.

  By the way, although it is desired to reduce the thickness of such a heat generating sheet depending on the application, if the thickness is reduced, the amount of constituent components to be retained decreases, and it is difficult to obtain high heat generation characteristics. .

JP 2003-102761 A

  The present invention relates to a sheet-like exothermic molded article that is thin and excellent in heat generation characteristics.

The present invention is a sheet-like exothermic molded body in which a breathable sheet is arranged on one side or both sides of a heat-generating sheet in which an electrolyte and water are contained in a heat-generating intermediate sheet containing an oxidizable metal, a water retention agent and a fibrous material. The exothermic intermediate sheet has a basis weight of 10 to 1000 g / m ² and a water retention agent content of 3 to 60% by weight, and the breathable sheet has a moisture permeability of 100 to 10000 g / (m ^2. -The sheet-like exothermic molded object which is 24h) is provided.

  According to the present invention, there is provided a sheet-like exothermic molded body that is thin and excellent in heat generation characteristics.

  The present invention will be described below based on preferred embodiments with reference to the drawings.

  FIG. 1 shows an embodiment of the sheet-like exothermic molded body of the present invention. In FIG. 1, the code | symbol 1 has shown the sheet-like exothermic molded object.

  As shown in FIG. 1, a sheet-like exothermic molded body 1 includes a heat-generating sheet containing an oxidizable metal, a water retention agent, and a fibrous material (hereinafter referred to as a heat-generating intermediate sheet, an electrolyte component when no later-described electrolyte component is included). And a water-containing sheet are referred to as a heat generating sheet.) Breathable sheets 3 are laminated on both sides of 2.

Sheet heating the molded body 1, preferably has a basis weight of 50~3000g / m ^2, and more preferably 50 to 1500 g / m ^2. When the basis weight is 50 g / m ² or more, even when using a material having a large specific gravity among oxidizable metals and the like, it is preferable in that a stable sheet can be formed. Further, when the basis weight is 3000 g / m ² or less, it is light and excellent in feeling of use, and is also preferable in terms of productivity and operability.

  The sheet-like exothermic molded body 1 preferably has an exothermic temperature of 30 to 100 ° C, and more preferably 35 to 90 ° C. Here, the heat generation attainable temperature is determined by cutting a 50 mm × 50 mm test piece from the heat generating sheet constituting the sheet-like exothermic molded body and then placing the air-permeable sheet and non-moisture permeable sheet constituting the sheet-like exothermic molded body on both sides. After bonding and packaging in a bag shape, a tester capable of supplying dry air of 5 liters / min into a sealed system in an environment of a volume of 4.2 liters and a relative humidity of 1% or less is prepared. It is the value which measured with the thermocouple the temperature of the lower side of the heat generating sheet when it stood still with the moisture permeable sheet side as the upper surface to generate heat. The heat generation temperature of the sheet-like exothermic molded body 1 is the above-described blending composition and the moisture permeability of the ventilation sheet (JIS Z208), such as products that require rapid heat generation depending on the product application, or products that need to be maintained at a relatively low temperature for a long time. Can be arbitrarily designed by a combination of the moisture permeability measured in step (hereinafter, simply referred to as moisture permeability in this specification).

The sheet-like exothermic molded body 1 preferably has a water vapor generation amount of 0.1 to 100 mg / (cm ² · 10 min), and more preferably 1 to 50 mg / (cm ² · 10 min). In the present specification, the term “water vapor generation amount” refers to, for example, a value 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 5 liters / min of dry air in a closed system. Let 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. 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) = (2.1 x s) / 60
Amount of water vapor per unit time A (g) = (P × D) / 1000 (1)

  The amount of water vapor generated in the sheet-like exothermic molded body 1 is the same as that described above in the case where a rapid heat generation is required depending on the use of the product, as well as the product that requires a long time at a relatively low temperature. Any combination can be designed.

  As the oxidizable metal contained in the exothermic intermediate sheet 2, an oxidizable metal conventionally used in this type of exothermic molded body can be used without 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. Means an average particle diameter measured by a laser diffraction method, etc.) is preferably 0.1 to 300 μm, and contains 50% by weight or more of 0.1 to 150 μm in particle diameter. More preferably, it is used.

  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 fiber length of 0.1 to 50 mm and a thickness of 1 to 1000 μm is used in terms of formability, mechanical strength of the obtained sheet, surface smoothness, and heat generation performance. It is preferable.

  The blending amount of the oxidizable metal in the exothermic intermediate sheet 2 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 obtained sheet-like exothermic molded body 1 can be increased to a level that a person feels hot by touching with a fingertip or the like. The amount of fibrous materials and adhesive components (flocculant, etc.) can be suppressed, so that the molded body has sufficient air permeability, and as a result, the reaction sufficiently occurs inside the molded body to sufficiently raise the heat generation temperature. be able to. Further, the heat generation time can be made sufficiently long, the water supply by the water retention agent can be made sufficient, and the oxidizable metal does not easily fall off. In addition, since the fibrous material and adhesiveness described later constituting the molded body can be maintained at a certain amount, mechanical strength such as bending strength and tensile strength can be made sufficient. Here, the compounding amount of the oxidizable metal in the exothermic intermediate sheet 2 can be determined by an ash test according to JIS P8128 or a thermogravimetric measuring instrument. In addition, for example, in the case of iron, it can be quantified by a vibration sample type magnetization measurement test or the like using the property that magnetization occurs when an external magnetic field is applied.

  As the water retention agent, a water retention agent that has been conventionally used for exothermic molded bodies can be used without any particular limitation. In addition to acting as a moisture retention agent, the water retention agent also has a function as an oxygen retention / supply agent for the oxidizable metal. Examples of the water retention agent include activated carbon (coconut husk charcoal, charcoal powder, calendar bituminous coal, peat, lignite), carbon black, acetylene black, graphite, zeolite, perlite, vermiculite, silica, cancrinite, fluorite and the like. Among these, activated carbon is preferably used because it has water retention ability, oxygen supply ability, and catalytic ability. As the water retention agent, it is preferable to use a powdery material having a particle size of 0.1 to 500 μm from the viewpoint that an effective contact state with an oxidizable metal can be formed. It is more preferable to use those containing at least wt%. As the water retention agent, a form other than the powder form as described above can be used. For example, a form of fiber form such as activated carbon fiber can also be used.

  The content of the water retaining agent in the exothermic intermediate sheet 2 is 3 to 60% by weight, preferably 5 to 50% by weight, and more preferably 7 to 40% by weight. When the content is 3% by weight or more, moisture necessary for maintaining the reaction to such an extent that the oxidizable metal rises to the temperature of the human body due to the oxidation reaction can be accumulated in the sheet-like exothermic molded body 1. Further, since the air permeability of the sheet-like exothermic molded body 1 is sufficiently ensured, the oxygen supply is sufficiently obtained and the exothermic molded body has high heat generation efficiency. When the blending amount is 60% by weight or less, the heat capacity of the sheet-like exothermic molded body 1 with respect to the obtained calorific value can be kept small, so that the exothermic temperature rises greatly, and a temperature rise that can be experienced when a person is warm is obtained. It is done. Further, since the occurrence of falling off of the water retaining agent and the decrease in the fibrous materials and adhesive components described later constituting the heat generating sheet 2 can be suppressed, sufficient mechanical strength such as bending strength and tensile strength can be obtained.

  Examples of the fibrous material include, for example, vegetable fibers (cotton, kabok, wood pulp, non-wood pulp, peanut protein fiber, corn protein fiber, soy protein fiber, mannan fiber, rubber fiber, hemp, and Manila hemp. , Sisal, New Zealand hemp, Rafu hemp, eggplant, rush, straw, etc.), animal fiber (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 with oxidizable metals and water retention agents. 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, from the viewpoints of the oxidizable metal, the fixability of the water retention agent, the flexibility of the resulting sheet-like exothermic molded article, the oxygen permeability resulting from the presence of voids, the production cost, etc., wood pulp, cotton Is preferably used.

  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 the water retaining agent is sufficiently good, the predetermined blending amount can be maintained, and the heat generation performance can be sufficiently exhibited. In addition, a sheet having a uniform thickness is obtained, the fixing between the fibrous material and the component is good, the component is difficult to fall off, and the bond strength derived from the entanglement between the component and the fibrous material or hydrogen bonding Can be given. Further, the mechanical strength such as bending strength and tensile strength can be sufficient, and the workability is also good.

The lower the CSF of the fibrous material, the better. However, in the case of normal pulp fiber-only papermaking, when the component ratio other than the fibrous material is low, the drainage is sufficiently good when the CSF is 100 ml or more, and dehydration. Can be sufficiently performed, and a heat-generating sheet having a uniform thickness is obtained, and blister breakage does not occur during drying, and the moldability is improved. In the present invention, since the ratio of components other than the fibrous material is high, it is possible to obtain a heat generating sheet with good drainage and uniform thickness. 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. When the zeta potential is negative, the fixing of the components such as the oxidizable metal and the water retaining agent to the fibrous material is good, the predetermined blending amount can be maintained, and the heat generation performance is excellent. It is possible to prevent a large amount of the component from being mixed in the wastewater, and it does not adversely affect 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. By setting the average fiber length in such a range, the mechanical strength such as bending strength and tensile strength of the resulting heat generating sheet can be sufficiently secured, and the air permeability of the heat generating sheet is good without the fiber layer becoming too dense. Thus, the oxygen supply is good and the heat generation is excellent. Further, since the fibrous material can be uniformly dispersed in the heat generating sheet, uniform mechanical strength can be obtained, and a heat generating sheet having a uniform thickness can be obtained. In addition, the fiber spacing does not become too wide, and the ability of the fiber to retain components such as the oxidizable metal and water retention agent is maintained, making it difficult for the component to fall off.

  The blending amount of the fibrous material in the exothermic intermediate sheet 2 is preferably 2 to 50% by weight, and more preferably 5 to 40% by weight. When the blending amount is 2% by weight or more, it is possible to sufficiently prevent the components such as the oxidizable metal and the water retention agent from falling off and to make the heat generating sheet sufficient. When the blending amount is 50% by weight or less, the heat capacity with respect to the heat generation amount of the exothermic molded body can be suppressed, the temperature rise can be made sufficient, and the obtained exothermic molded body 1 in the sheet-like exothermic molded body 1 can be obtained. Since the ratio of the components can be secured to a certain level or more, the desired heat generation performance can be sufficiently obtained, which is preferable.

  The ratio of the content of the oxidizable metal and the activated carbon in the exothermic intermediate sheet 2 is preferably oxidizable metal: activated carbon = 45: 1 to 0.3-1 (weight ratio), more preferably coated. Oxidizing metal: activated carbon = 20: 1 to 1: 1, and the total content of the oxidizable metal and the water retention agent in the exothermic intermediate sheet 2 is 50 to 98% by weight, more preferably 60 to 95% by weight. Preferably there is. When the content ratio of these components is within the above range, the oxidation efficiency of the oxidizable metal is high, and the heat generation performance of the sheet-like heat-emitting molded body can be effectively improved.

It is preferable that a flocculant is added to the exothermic intermediate sheet 2 as described later.
In addition, the heat generating sheet 2 includes additives usually used for paper making such as a sizing agent, a colorant, 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 basis weight per sheet of the heat generating intermediate sheet 2 is 10 to 1000 g / m ² , and more preferably 50 to 600 g / m ² . When the basis weight is 10 g / m ² or more, a particularly stable sheet can be formed when an oxidizable metal having a large specific gravity is used. When the basis weight is 1000 g / m ² or less, it is lightweight and has a good feeling of use, and productivity and operability are also good.

The breaking length of the exothermic intermediate sheet is preferably 100 to 4000 m, and more preferably 200 to 3000 m. When the breaking length is within such a range, handling during use and production / operation can be facilitated. Here, the tearing length is determined by cutting a test piece having a length of 150 mm × width of 15 mm from a sheet-like exothermic molded body 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 ])

  The thickness of the exothermic intermediate sheet 2 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, oxidizable metal, water retention agent, and other components are well fixed, and a stable and uniform thickness and composition distribution can be obtained. It becomes difficult for the sheet to be broken due to the occurrence of the occurrence, and the productivity and workability are improved. When the thickness is 1.2 mm or less, the bending strength of the sheet can be secured, and brittle fracture is not easily caused, and the flexibility is also good, particularly bending and stretching of body parts such as elbows, knees, and faces. When attached to a site, the wearability is poor and it can be used without a sense of incongruity. In terms of productivity, paper layer formation time and drying time are hardly delayed, operability is good, heat generation performance is good, and workability such as bending is also excellent.

  As the electrolyte contained in the heat generating sheet 2, an electrolyte that has been conventionally used for this type of exothermic molded body 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, and iron chloride (first and second) 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 in the heat generating sheet 2 is preferably 0.5 to 30% by weight, more preferably 1 to 25% by weight in terms of the weight ratio of water in the heat generating sheet 2. The blending amount of 0.5% by weight or more is preferable because the oxidation reaction of the obtained sheet-like exothermic molded body 1 can sufficiently proceed. When the blending amount is 30% by weight or less, precipitation of the electrolyte hardly occurs, the air permeability of the sheet-like exothermic molded body 1 is good, the electrolyte necessary for the heat generating function can be secured, and sufficient water is provided. It is preferable because it is supplied to an oxidizable metal or the like, has excellent heat generation performance, and can uniformly mix an electrolyte with the sheet-like exothermic molded body 1.

  The heat generating sheet 2 preferably has a moisture content (weight moisture content, hereinafter the same) of 5 to 80%, and more preferably 10 to 60%. When the water content is 5% or more, it is possible to sufficiently secure moisture necessary for continuing the oxidation reaction, and to prevent the oxidation reaction from being terminated in the middle. Since moisture can be supplied uniformly, uniform heat generation performance can be obtained. When the water content is 80% or less, the heat capacity of the sheet-like exothermic molded body 1 obtained can be kept low, the heat generation temperature can be sufficiently increased, and the air flow of the sheet-like exothermic molded body 1 can be increased. Therefore, the heat generation performance is excellent, and the shape retention and mechanical strength are sufficiently obtained.

The basis weight of the heat generating sheet 2 is preferably 10 to 2000 g / m ^2, more preferably from 50 to 1500 g / m ^2, further preferably 100 to 1000 g / m ^2. When the basis weight is 10 g / m ² or more, a particularly stable sheet can be formed when an oxidizable metal having a large specific gravity is used. When the basis weight is 2000 g / m ² or less, it is lightweight and has a good feeling of use, and productivity and operability are also good.

  The exothermic sheet 2 preferably has an exothermic temperature of 30 to 100 ° C, and more preferably 35 to 90 ° C. The heat generation attainable temperature of the heat generating sheet 2 can be arbitrarily designed by a combination of the above-described blending compositions according to the product application.

The heat generating sheet 2 preferably has a water vapor generation amount of 0.1 to 100 mg / (cm ² · 10 min), and more preferably 1 to 50 mg / (cm ² · 10 min). The amount of water vapor generated in the exothermic sheet 2 can be arbitrarily designed according to the combination of the above-described blending compositions, depending on the product use as well as the heat generation arrival time.

The breathable sheet 3 is moisture permeability ^{100~10000g / (m 2 · 24h)} , it is preferably ^{150~8000g / (m 2 · 24h)} , with 200~6000g / (m ² · 24h) More preferably. When the moisture permeability is in such a range, the rate of heat dissipation is suppressed, and the exothermic reaction proceeds quickly, resulting in high heat generation. Therefore, quick heat generation and water vapor generation are possible even when water vapor is generated. The breathable sheet 3 may be breathable on the entire surface, or may be partially breathable.

The breathable sheet 3 preferably has a basis weight of 10 to 200 g / m ² , and more preferably ²⁰ to 100 g / m ² . When the basis weight of the air-permeable sheet 3 is within such a range, the sheet is thin, the flexibility is not impaired, and the softness of the heat generating sheet 2 is not impaired.

  The breathable sheet 3 includes a sheet made of a resin such as polyolefin such as polyethylene and polypropylene, polyester, polyamide, polyurethane, polystyrene, polyethylene-vinyl acetate copolymer, and the like, and the resin and inorganic. A mixture sheet of fillers that has undergone interfacial exfoliation by stretching, micropores formed by utilizing the interfacial exfoliation of its crystal structure, and micropores that communicate with each other using open cells by foam molding Etc. Moreover, the synthetic | combination pulp, such as polyolefin, semi-synthetic fibers, such as wood pulp, rayon, and acetate, the nonwoven fabric formed from vinylon fiber, polyester fiber, a woven fabric, synthetic paper, paper, etc. are mentioned. A plurality of breathable sheets 3 can be used in an overlapping manner.

Next, the manufacturing method of the sheet-like exothermic molded object 1 is demonstrated.
In producing the sheet-like exothermic molded body 1, first, a raw material composition (slurry) containing the oxidizable metal, the water retention agent, the fibrous material, and water is prepared, and the exothermic intermediate is prepared from the raw material composition. The sheet 2 is preferably formed by papermaking.

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. Among these flocculants, anionic colloidal silica, bentonite, etc. and cation are used in terms of sheet surface properties, texture formation, moldability improvement, fixing rate of materials such as oxidizable metals and water retention agents, and paper strength. The combination of cationic starch and polyacrylamide, anionic carboxymethylcellulose sodium salt, polyacrylamide and cationic polyamide epichlorohydrin, and the combination of cationic and anionic agents such as polyacrylamide 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 coagulation effect is excellent, the falling off of components such as oxidizable metals and water retention agents during papermaking can be suppressed, and the raw material composition becomes uniform, and the heat generation is uniform in thickness and composition. It is excellent in that a sheet can be obtained. When the added amount is 5% by weight or less, it is possible to suppress the occurrence of tearing, burning, scorching, etc., sticking to a drying roll during drying, excellent productivity, and maintaining a good potential balance of the raw material composition. This is excellent in that the amount of the component dropped into the white water during papermaking can be suppressed. Moreover, the oxidation reaction of the exothermic sheet proceeds, and the storage stability such as exothermic 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. A concentration of 0.05% by weight or more is preferable in that a large amount of water is not required, and it is not necessary to form a heat generating sheet for a long time, and a heat generating sheet having a uniform thickness can be formed. When the concentration is 10% by weight or less, the dispersion state of the raw material composition is good, the surface property of the obtained sheet is excellent, and the sheet having a uniform thickness is obtained.

Next, the raw material composition is made to form the exothermic intermediate sheet.
Examples of the paper making method for the heat generating intermediate sheet include a paper making method using a continuous paper making type circular paper making machine, a long paper making machine, a Yankee paper making machine, a twin wire paper making machine, and a batch type paper making method. For example, there is an acupuncture method. Furthermore, an exothermic intermediate 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. Also, the exothermic intermediate sheets obtained by papermaking the raw material composition are laminated together in multiple layers, or a sheet-like material obtained from a composition having a composition different from the raw material composition is attached to the exothermic intermediate sheet. An exothermic intermediate sheet can also be formed by combining them.

  The exothermic intermediate sheet is 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 paper making (shape retention) and maintaining the mechanical strength. Is preferable, and it is more preferable to dehydrate it to 60% or less. Examples of the method for dehydrating the exothermic intermediate 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 exothermic intermediate sheet containing the oxidizable metal (having heat reactivity in a normal atmosphere) is actively dried to separate the moisture, thereby suppressing oxidation of the oxidizable metal during the manufacturing process, long-term It is possible to obtain an exothermic intermediate sheet having excellent storage stability. 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 that the exothermic intermediate sheet is dried after the exothermic intermediate sheet is formed and before the electrolytic electrolyte solution is contained.

  The exothermic intermediate 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. By setting the heating and drying temperature of the exothermic intermediate sheet to such a temperature range, the drying time can be shortened, so that the oxidation reaction of the oxidizable metal accompanying the drying of moisture can be suppressed, and the exothermic property of the resulting exothermic sheet can be reduced. Decline can be prevented. In addition, since only the front and back layers of the heat generating sheet can suppress the oxidation reaction of the oxidizable metal, it is possible to prevent discoloration to light brown. In addition, since the performance deterioration of the water retaining agent can be suppressed, the heat generation effect of the heat generating sheet can be maintained, and the structure of the heat generating sheet can be destroyed due to the rapid evaporation of moisture inside the heat generating intermediate sheet. Can be prevented.

  The moisture content of the exothermic intermediate sheet 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, and heat generation performance and mechanical strength are improved. No change and excellent.

  The drying method of the exothermic intermediate sheet can be appropriately selected according to the thickness of the exothermic intermediate sheet, the processing method of the exothermic intermediate 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 exothermic intermediate sheet 2 is preferably formed (dehydrated and dried) in an inert gas atmosphere. However, as described above, the exothermic intermediate sheet does not contain an electrolyte that serves as an oxidizing aid. The molding can also be performed in a normal air atmosphere. For this reason, manufacturing equipment can be simplified. Since the obtained exothermic intermediate sheet is thin and difficult to tear, it can be rolled up as necessary.

  The dried exothermic intermediate sheet 2 may be pierced by creping, slitting, trimming, or needle punching as necessary. 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 air-permeable sheet 3 is laminated on the dried exothermic intermediate sheet 2 so as to have the above-described layer structure to form a multilayer. This multilayering process can be performed by a conventionally known multilayering process. Concavity and convexity may be formed by embossing or the like with multiple layers.

  Next, the exothermic intermediate sheet 2 contains the electrolyte. The step of containing the electrolyte is preferably performed in an inert gas atmosphere such as nitrogen or argon. However, when the electrolyte is added by impregnation with the electrolytic solution, the oxidation reaction immediately after the addition is gentle, The electrolyte may be contained in an air atmosphere.

  The method of adding the electrolyte to the exothermic intermediate sheet can be appropriately set according to the processing method of the exothermic intermediate sheet after paper making, the moisture content, the form, the layer structure of the multilayered sheet, and the like. Examples of the method of containing the electrolyte include a method of impregnating the exothermic intermediate sheet with an electrolyte solution having a predetermined concentration of the electrolyte, and adding the electrolyte having a predetermined particle size as a solid to be contained in the exothermic intermediate sheet. And the like. From the standpoint that the electrolyte can be uniformly contained in the exothermic intermediate sheet and that the moisture content can be adjusted at the same time, a method of impregnating an electrolyte solution of a predetermined concentration is preferable.

  As described above, when the exothermic intermediate sheet is impregnated with the electrolyte, the impregnation method can be appropriately selected according to the form such as the thickness of the exothermic intermediate sheet and the water content. The impregnation method includes a method of spray-coating the electrolyte solution of a predetermined concentration onto the exothermic intermediate sheet, and injecting the electrolyte solution into a part of the exothermic intermediate sheet with a syringe or the like, and utilizing the capillary action of the fibrous material And a method of penetrating the whole exothermic intermediate sheet, a method of coating with a brush, a method of immersing in the electrolytic solution, a gravure coating method, a reverse coating method, a doctor blade method, etc., among these, A spray coating method is preferable because it can be uniformly distributed, is simple, and requires relatively little equipment cost. In addition, in the case of products with complicated shapes and layer configurations, the concentration of the specified concentration is improved from the viewpoint that productivity is improved, the final finishing can be performed as a separate process, the production flexibility is improved, and the equipment is simplified. A method of injecting the electrolytic solution with a syringe or the like is preferable. This method of injecting the electrolytic solution can also be performed after the multilayered sheet is accommodated in a predetermined container.

  After the electrolyte is contained in the exothermic intermediate sheet as described above, the moisture content is adjusted and stabilized as necessary to obtain a sheet-like exothermic molded body 1. Then, if necessary, it can be trimmed and processed into a predetermined size. The obtained sheet-like exothermic molded body 1 is provided by being packaged with an oxygen-impermeable packaging material in an unused state.

  As described above, the sheet-like exothermic molded body 1 of the present embodiment is used because the breathable sheets are laminated on the front and back of the heat generating sheet having the above composition and having a predetermined tear length. High exothermic properties can be obtained immediately, and flexibility is also excellent. Further, detachment of the constituent material can be suppressed.

  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.

  Further, in the sheet-like exothermic molded body of the present invention, it is preferable that a breathable sheet is laminated on the front and back of the exothermic sheet 2 as in the above embodiment, but the breathable sheet may be laminated only on one side. .

Hereinafter, the sheet-like exothermic molded body of the present invention will be described more specifically with reference to examples.
Exothermic intermediate sheets having the solid content-containing compositions shown in Table 1 were prepared as in Examples 1 to 4 and Comparative Examples 1 to 3 below. Further, a heat-generating sheet and a sheet-like heat-formed body were produced from the obtained heat-generating intermediate sheet as follows. And about the obtained exothermic intermediate sheet, exothermic sheet, and sheet-like exothermic molded object, the thickness, basic weight, and exothermic characteristic were investigated as follows. The results are shown in Tables 1 and 2.

[Example 1]
<Combination of raw material composition>
Oxidizable metal: iron powder, manufactured by Dowa Mining Co., Ltd., trade name “RKH”: 8.0 g
Fibrous material: Pulp fiber (Fletcher Challenge Canada, trade name NBKP “Mackenzi (adjusted to CSF 200 ml)”): 1.5 g
Water retention agent: Activated charcoal (Nippon Enviro Chemicals Co., Ltd., trade name “Carborafyn”) 0.5 g
Flocculant: Polyamide epichlorohydrin resin (manufactured by Seiko PMC, trade name “WS552”) 0.14 g
Sodium carboxymethylcellulose (Daiichi Kogyo Seiyaku Co., Ltd., trade name “Serogen WS-C”, 0.017 g
Water: Industrial water 1500g

<Electrolyte>
Electrolyte: Purified salt (NaCl)
Water: Industrial water Electrolyte concentration: 5.0% by mass

<Paper making conditions>
The raw material composition was stirred at 300 rpm for 1 minute. Then, according to JIS P8209, paper was made using Kumagaya Riki Kogyo Co., Ltd. standard square sheet machine and 80 mesh papermaking net. Then, using a KRK rotary dryer manufactured by Kumagai Riki Kogyo Co., Ltd., drying was performed so that the water content was 1% by mass or less, thereby obtaining an exothermic intermediate sheet.

<Preparation of exothermic sheet>
The obtained exothermic intermediate sheet is cut into 50 mm × 50 mm, and the electrolyte is injected so that the amount of the electrolyte is 37.5% with respect to the weight of the exothermic intermediate sheet, and penetrates the entire sheet using capillary action. The exothermic sheet was obtained.

<Preparation of sheet-like exothermic molded body>
The following breathable sheet and the following non-breathable sheet were laminated on the top and bottom of the obtained heat generating sheet, and the periphery of the heat generating sheet was joined by heat sealing to prepare a sheet-shaped heat generating molded body having a three-layer structure.
Breathable sheet: polyethylene perforated sheet, water vapor transmission rate 5000 g / (m ² · 24 h), basis weight 36 g / m ²
Non-breathable sheet: PE film, basis weight 20 g / m ²
Non-breathable sheet surface agent: PET / PE core-sheath fiber air-through nonwoven fabric, basis weight 20 g / m ²

[Example 2]
A sheet-like exothermic molded body was produced in the same manner as in Example 1 except that the amount of iron powder was 7.0 g and the amount of activated carbon was 1.5 g.

Example 3
A sheet-like exothermic molded body was produced in the same manner as in Example 1 except that the amount of iron powder was 5.0 g and the amount of activated carbon was 3.5 g.

Example 4
A sheet-like exothermic molded body was produced in the same manner as in Example 1 except that the amount of iron powder was 3.5 g and the amount of activated carbon was 5.0 g.

[Comparative Example 1]
A sheet-like exothermic molded body was prepared in the same manner as in Example 1 except that the amount of iron powder was 8.4 g, the amount of activated carbon was 0.1 g, and the amount of the electrolyte was 16.7% with respect to the weight of the exothermic intermediate sheet. Produced.

[Comparative Example 2]
A sheet-like exothermic molded body was produced in the same manner as in Example 1 except that the amount of iron powder was 8.4 g and the amount of activated carbon was 0.1 g. A sheet-like exothermic molded body was produced in the same manner as in Example 1 except that.

[Comparative Example 3]
A sheet-like exothermic molded body was produced in the same manner as in Example 1 except that the blending amount of iron powder was 1.5 g and the blending amount of activated carbon was 7.0 g.

[Evaluation of heat generation characteristics]
A tester capable of supplying dry air at 23 ° C. to a sealed system at a rate of 4.2 liters and a humidity of 1 RH% or less with a sheet-like exothermic molded body (50 × 50 cm) containing an electrolyte. It prepared and it left still with the said moisture-permeable sheet side as the upper surface inside, and it was made to heat | fever. And the temperature under the said heat_generation | fever sheet | seat was measured with the thermocouple, and it was set as the heat_generation | fever temperature. In this evaluation, the obtained maximum temperature, the arrival time up to 36 ° C. based on the human body temperature, and the maintenance time of 36 ° C. or more were set as evaluation targets.

  As shown in Table 1 and FIGS. 2 and 3, it was found that the sheet-like exothermic molded bodies of the examples were thin and excellent in heat generation characteristics. In particular, the rate of heat dissipation was suppressed by the ventilation sheet, and the exothermic reaction proceeded to reach a sufficient exothermic temperature. On the other hand, the sheet-like exothermic molded body of the comparative example had a low maximum temperature and had a heat generation characteristic that was difficult to feel when a person was warm.

  There is no restriction | limiting in particular in the use of the sheet-like exothermic molded object of this invention. In addition to its use as a heating element, it uses thin and quick heat generation characteristics. It can also be applied to house care applications such as ventilation fans, car care applications such as car cleaning, waxing, and skin care applications such as facial and body cleaning, disinfection, moisturizing, and makeup removal.

It is the perspective view which fractured | ruptured the part which shows typically one Embodiment of the sheet-like exothermic molded object of this invention. It is a figure which shows the time-dependent change of the exothermic temperature of the Example of this invention. It is a figure which shows the time-dependent change of the exothermic temperature of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet-like exothermic molded body 2 Exothermic sheet 3 Breathable sheet

Claims (4)

A sheet-like exothermic molded body in which a breathable sheet is disposed on one side or both sides of an exothermic sheet containing an electrolyte and water in an exothermic intermediate sheet containing an oxidizable metal, a water retention agent and a fibrous material,
The exothermic intermediate sheet has a basis weight per sheet of 10 to 1000 g / m ² and a content of the water retention agent of 3 to 60% by weight,
The breathable sheet is a sheet-like exothermic molded article having a moisture permeability of 100 to 10,000 g / (m ² · 24 h).   The ratio of the oxidizable metal and the content of the water retaining agent in the heat generating sheet is 45: 1 to 0.3: 1 (weight ratio), and the oxidizable metal in the heat generating intermediate sheet The sheet-like exothermic molded article according to claim 1, wherein the total content of water and a water retention agent is 50 to 98% by weight.   The sheet-like exothermic molded body according to claim 1 or 2, wherein the heat generating intermediate sheet has a breaking length of 100 to 4000 m. The sheet-like exothermic molded body according to any one of claims 1 to 3, wherein the oxidizable metal is iron powder, the water retention agent is activated carbon, and the fibrous material is pulp.

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