JP2013094171A - Heating element manufacturing method and the heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a heating element that effectively prevents the heating element from becoming hard caused by oxidation of an oxidizable metal.SOLUTION: The method is used for manufacturing a heating element in which one surface of a base-material sheet is provided with a layer composed of a heating composition containing oxidizable metal particles, a carbon component, water and an electrolyte. The method has a process in which the layer composed of the heating composition is formed on one surface of the base-material sheet, and then, a plurality of first slit rows and a plurality of second slit rows are formed on the base-material sheet. The first slit row comprises a plurality of slits arranged extending in one direction. The second slit row comprises a plurality of slits arranged extending in one direction toward the direction that intersects with the first slit row.

Description

  The present invention relates to a method for manufacturing a heating element. The present invention also relates to a heating element.

  The present applicant has previously proposed an eye heating device that applies heat to the eyes and around the eyes (see Patent Document 1). The eye heating device includes an eye mask-shaped main body, and the main body includes a skin-side sheet, an outer sheet, and a sheet-like heating element disposed therebetween. The sheet-like heating element has a plurality of slits extending in one direction, whereby the sea-like heating element is easily deformed. As a result, the heating device for eyes is deformed so as to match the curved shape of the face, the fitting property is improved, and the usability is good.

  By the way, a heating tool having a heating element using an oxidation reaction of an oxidizable metal, including the above-described heating element for the eye, tends to become harder as the oxidation proceeds. Due to this, even if the fitting property of the heating tool to the body is good at the initial stage of use, the fitting property tends to decrease as the oxidation proceeds. In order to prevent the heating element from becoming hard as the oxidation proceeds, for example, it has been proposed to accommodate the heating element in a cell divided into a plurality of small sections (see, for example, Patent Documents 2 and 3). .

JP 2009-82570 A JP 2006-51191 A JP 2007-44892 A

  However, when the heating element is accommodated in the cell, the thickness of the entire heating tool tends to increase, and as a result, the feeling of mounting the heating tool tends to decrease. Moreover, the packaging container for shielding and heating the heating tool from the air becomes large.

  Therefore, the subject of this invention is providing the manufacturing method of a heat generating body which can eliminate the fault which the prior art mentioned above has, and a heat generating body.

The present invention is a method for producing a heating element in which a layer of a heat generating composition containing particles of an oxidizable metal, a carbon component, water and an electrolyte is provided on one surface of a base sheet,
After forming the layer of the exothermic composition on one surface of the base sheet, the base sheet has a step of forming a plurality of first slit rows and a plurality of second slit rows,
The first slit row is composed of a plurality of slits arranged to extend in one direction,
The second slit row provides a method for manufacturing a heating element, which is composed of a plurality of slits arranged so as to extend in one direction toward the direction intersecting the first slit row.

Moreover, the present invention is provided with a layer of a heat generating composition containing particles of an oxidizable metal, a carbon component, water and an electrolyte on one surface of a base sheet,
The base sheet is formed with a plurality of first slit rows composed of a plurality of slits arranged so as to extend in one direction, and extends in one direction toward a direction intersecting the first slit row. A plurality of second slit rows composed of a plurality of slits arranged in such a manner,
The present invention provides a heating element in which each slit is arranged so that the slit in the first slit row and the slit in the second slit row are in a non-intersecting state.

  According to the present invention, it is possible to effectively prevent the heating element from becoming hard due to oxidation of the oxidizable metal. Therefore, it is difficult for the user to feel uncomfortable wearing from the beginning to the end of use.

FIG. 1 is a plan view showing an arrangement state of slits formed in a base sheet in a heating element of the present invention. FIG. 2 is a schematic view showing an apparatus suitably used for producing the heating element of the present invention. 3 (a) and 3 (b) are schematic views showing a state in which slits are formed in the base sheet using the apparatus shown in FIG. FIG. 4 is a longitudinal sectional view of a heating tool provided with the heating element of the present invention. FIGS. 5A and 5B are plan views (corresponding to FIG. 1) showing another arrangement state of slits formed in the base sheet in the heating element of the present invention. FIG. 6 is a schematic diagram showing a method for measuring a three-point bending load. FIG. 7 is a graph showing the relationship between the three-point bending load and time of the heating tools obtained in the examples and comparative examples.

  The present invention will be described below based on preferred embodiments with reference to the drawings. First, a preferred embodiment of a heating element obtained according to the production method of the present invention will be described. The heating element includes a base sheet and a layer of a heat generating composition (hereinafter also referred to as “heat generation layer”) provided on one surface of the base sheet.

  Examples of the substrate sheet include fiber sheets, synthetic resin films, and laminates thereof. A fiber sheet is preferably used as the substrate sheet from the viewpoint of easily forming the heat generating layer and capable of stably holding the formed heat generating layer. Moreover, since the fiber sheet has water absorption, it is preferable to use the fiber sheet from the viewpoint of controlling the moisture content of the heat generating layer.

  Examples of the fiber sheet include various sheets containing a fiber material, for example, paper such as wet papermaking and dry papermaking, woven fabric, non-woven fabric, knitted fabric, or composite sheets thereof. It is particularly preferable to use paper or non-woven fabric.

  Particularly preferably used fiber sheets include hydrophilic fibers. This fiber sheet is produced by, for example, a wet papermaking method or a dry papermaking method. As the hydrophilic fiber contained in the fiber sheet, either natural fiber or synthetic fiber can be used. By using hydrophilic fibers as the constituent fibers of the fiber sheet, there is an advantage that hydrogen bonds are easily formed with the oxidizable metal contained in the heat generating layer, and the shape retention of the heat generating layer is improved. Further, the use of hydrophilic fibers also has the advantage that the water absorption or water retention of the fiber sheet is improved and the water content of the heat generating layer can be easily controlled. From these viewpoints, cellulose fibers are preferably used as the hydrophilic fibers. Chemical fibers (synthetic fibers) and natural fibers can be used as the cellulose fibers.

  The above-mentioned various hydrophilic fibers preferably have a fiber length of 0.5 to 6 mm, particularly 0.8 to 4 mm from the viewpoint of easy production of a fiber sheet by a wet papermaking method or a dry papermaking method. .

  In addition to the above-described hydrophilic fibers, heat-fusible fibers may be blended in the fiber sheet as necessary. By blending this fiber, the strength of the fiber sheet in a wet state can be increased. The compounding amount of the heat-fusible fiber is preferably 0.1 to 10% by mass, particularly 0.5 to 5% by mass, based on the total amount of fibers in the fiber sheet.

  The fiber sheet may include particles of a superabsorbent polymer. This fiber sheet may be (a) one sheet in a state where the superabsorbent polymer particles and the hydrophilic fiber are uniformly mixed. Further, in this fiber sheet, (b) the superabsorbent polymer particles are mainly present in a substantially central region in the thickness direction of the fiber sheet, and the particles are substantially present on the surface of the fiber sheet. It can also be one-ply with no structure. Further, this fiber sheet may be (c) a laminate of two fiber sheets in which particles of superabsorbent polymer are arranged between the same or different fiber sheets containing hydrophilic fibers. Of the fiber sheets that can take various forms, it is preferable to use the fiber sheet having the form (b) from the viewpoint of easily controlling the moisture content of the heat generating layer.

  As described above, the base sheet made of the fiber sheet contains particles of a superabsorbent polymer. The location of the superabsorbent polymer particles in the base sheet is as described above. As the superabsorbent polymer, it is preferable to use a hydrogel material that can absorb and hold a liquid having a weight 20 times or more of its own weight and can be gelled. The shape of the particles can be spherical, massive, grape bunches, fibers and the like. The particle size of the particles is preferably 1 to 1000 μm, particularly preferably 10 to 500 μm. Specific examples of superabsorbent polymers include starch, crosslinked carboxylmethylated cellulose, polymers or copolymers of acrylic acid or alkali metal acrylates, polyacrylic acid and salts thereof, and polyacrylate graft polymers. Is mentioned.

  The ratio of the superabsorbent polymer in the base sheet is 10 to 70% by weight, particularly 20 to 55% by weight, and the viewpoint of making the water absorption or water retention of the base sheet suitable and the heat generating layer This is preferable from the viewpoint of controlling the water content. This ratio is a value measured for the base sheet in a dry state before the heat generation layer is formed on the base sheet.

The base sheet preferably has a basis weight of 10 to 200 g / m ² , particularly 35 to 150 g / m ² . By setting the basis weight of the base sheet within this range, sufficient strength of the base sheet in a wet state can be secured, and water absorption or water retention of the base sheet should be suitable. Can do. On the other hand, the basis weight of the superabsorbent polymer contained in the base sheet is preferably 5 to 150 g / m ² , particularly 10 to 100 g / m ² . By setting the basis weight of the superabsorbent polymer within this range, the water absorption or water retention of the base sheet can be further improved. Moreover, it becomes easier to control the moisture content of the heat generating layer. These basis weights are values measured for the base sheet in a dry state before the heat generation layer is formed on the base sheet.

  The substrate sheet can be produced by, for example, the airlaid method when it is in the form of (a). In the case of (b), it can be produced, for example, by the wet papermaking method described in JP-A-8-246395 related to the previous application of the present applicant. In the case of (c), it can be produced by the airlaid method or the wet papermaking method.

  The base sheet is provided with a heat generating layer on at least one surface thereof. The heat generating layer is provided over the entire surface of the base sheet, or is provided so that a part of the surface of the base sheet is exposed. For example, a plurality of heating layers formed in a stripe shape can be arranged at a predetermined distance. Moreover, the heat generating layer may be provided only on one side of the base sheet, or may be provided on both sides. As another embodiment, a heat generating layer may be provided between two identical or different substrate sheets. When the heat generating layer is provided between the two base material sheets, the heat generating layer is effectively prevented from sticking to a packaging material described later. When the heat generating layer is provided between the two substrate sheets, one of the substrate sheets may not include the superabsorbent polymer particles. The heat generating layer is a water-containing layer containing particles of an oxidizable metal, a carbon component, water, and an electrolyte. The heat generating layer may be present on the base sheet, or the lower part of the heat generating layer may be embedded in the base sheet depending on the type of the base sheet. Among these, it is preferable that the lower part of the heat generating layer is buried in the base material sheet. For example, it is preferable that the base sheet is made of a fiber sheet, and a part of the solid content constituting the heat generating layer is supported in a three-dimensional network formed on the fiber sheet. Since part of the heat generation layer is embedded in the base sheet, the unity of the heat generation layer and the base sheet is increased, and the heat generation layer is removed from the base sheet (before, during, and after use). Effectively prevented.

  Examples of the oxidizable metal contained in the heat generating layer include iron, aluminum, zinc, manganese, magnesium, calcium and the like. The particle size of the oxidizable metal particles can be, for example, about 0.1 to 300 μm. As the carbon material, it is preferable to use a carbon material that functions as a moisture retention agent and also has a function as an oxygen retention / supply agent for an oxidizable metal. Examples of the carbon material include activated carbon (coconut shell charcoal, charcoal powder, calendar bituminous coal, peat, lignite), carbon black, acetylene black, graphite and the like. As the electrolyte, an electrolyte capable of dissolving an oxide formed on the surface of the oxidizable metal particles is used. Examples thereof include alkali metal, alkaline earth metal or transition metal sulfates, carbonates, chlorides or hydroxides. Among these, chlorides of alkali metals, alkaline earth metals or transition metals are preferably used from the viewpoint of excellent conductivity, chemical stability and production cost, and particularly sodium chloride, potassium chloride, calcium chloride, magnesium chloride, chloride. Ferrous and ferric chloride are preferably used.

On the condition that the basis weight of the base sheet is in the above-mentioned range, the amount of the oxidizable metal in the heating element is 100 to 3,000 g / m ² , particularly 200 to 1,500 g, expressed in basis weight. / M ² is preferable from the viewpoint of securing a sufficient calorific value. The amount of the carbon material in the heating element is preferably 4 to 300 g / m ² , particularly 4 to 80 g / m ² , especially 8 to 50 g / m ² , from the viewpoint of maintaining stable heat generation for a long time. For the same reason, the amount of the electrolyte in the heating element is preferably 4 to 80 g / m ² , particularly 4 to 40 g / m ² , particularly 5 to 30 g / m ² . These basis weights are values in the case where one layer of heat generation layer is formed on one side of the base sheet. Therefore, when the heat generating layers are formed on both sides of the base sheet, these basis weights are double the above-mentioned values. Further, the basis weight is appropriately adjusted according to the specific application of the heating element.

  As described above, the heat generating layer is in a water-containing state. The moisture content of the heat generating layer is preferably 5 to 50% by mass, particularly 6 to 40% by mass. By setting the moisture content of the heat generating layer within this range, the fluidity of the heat generating layer is appropriately reduced. As a result, the slit can be formed in the base sheet without changing the heat generation layer in the slit forming step for the base sheet described later. The moisture content of the heat generating layer is measured with respect to a portion located above the surface of the base sheet. Therefore, the site | part embedded in the base material sheet among heat_generation | fever layers is excluded from the measuring object of a moisture content. A specific method for measuring the moisture content of the heat generating layer is as follows. That is, the exothermic layer at a position located above the surface of the base sheet is taken out in a nitrogen environment, and its mass is measured. Thereafter, moisture is removed for 2 hours in a drying furnace at a temperature of 105 ° C. in a vacuum state, the mass is measured again, and the water content is measured. The moisture content of the heat generating layer is a value per heat generating layer.

  The heating element of the present invention has one of the features in that a plurality of slits are formed in the base sheet. For example, as illustrated in FIG. 1, the base sheet is formed with a first slit row L <b> 1 including a plurality of first slits S <b> 1 arranged to extend in the first direction X. The first slit row L1 is formed in a plurality of rows over the second direction Y of the base sheet 1. Further, the base sheet 1 is formed with a second slit row L2 including a plurality of second slits S2 arranged so as to extend in a second direction Y that is a direction intersecting the first direction X. Yes. The second slit row L2 is formed in a plurality of rows over the first direction X of the base sheet 1. The first slit S1 and the second slit S2 are simply formed by cutting the base sheet 1, that is, the cut is formed, but the opening may not be formed, or It may be narrow and open.

  By forming the slit rows L1 and L2 extending in two different directions, even if the heat generation layer becomes hard due to oxidation of the oxidizable metal, the base sheet 1 on which the slit rows L1 and L2 are formed is formed. Since the flexibility remains, it becomes difficult to perceive the hardness of the entire heating element. In addition, since it is not necessary to provide a plurality of heating elements in a cell shape, the heating elements do not become excessively thick and the fitting property is not reduced. As a result, the heating tool provided with the heating element of the present invention is less likely to cause discomfort during mounting from the beginning to the end of use. Further, as a result of the examination by the present inventors, it has been found that the formation of the slits S1 and S2 does not particularly affect the heat generation characteristics of the heat generator 1.

  The flexibility of the base sheet 1 is generated by forming slit rows L1 and L2 extending in two different directions. From the viewpoint of making this flexibility even more remarkable, it is preferable to set the crossing angle between the first slit row L1 and the second slit row L2 to 60 to 120 degrees, and to 80 to 100 degrees. Even more preferred. In particular, L1 and L2 are preferably orthogonal. In particular, it is preferable that the first slit row L1 and the second slit row L2 are orthogonal from the viewpoint of developing substantially the same flexibility in any direction within the surface of the base sheet 1. The term “perpendicular” as used herein is unavoidable not only in the case where both slit rows L1 and L2 intersect at 90 degrees, but also in the heating element manufacturing method described later due to manufacturing conditions and fluctuations in the manufacturing apparatus. This includes the case where the crossing angle of both slit rows L1, L2 slightly varies from 90 degrees.

  The first slit row L1 and the second slit row L2 extend in directions intersecting with each other, and each first slit S1 constituting the first slit row L1 and each second constituting the second slit row L2. It is preferable that the slit S2 is disposed so as not to intersect. When the slits S1 and S2 are arranged in this way, there is an advantage that the region surrounded by the slits S1 and S2, for example, the region indicated by reference numeral 1a in FIG. is there. In addition, since the heating elements are not completely divided individually, the heating element in the storage state is compared with the conventional technology (see Patent Documents 2 and 3) in which the heating elements are divided into small sections. There is also an advantage that there is little deterioration. Furthermore, in the manufacturing method to be described later, when the electrolyte is sprayed in a powder state, it is easy to make the concentration of the sprayed electrolyte uniform over the entire heating layer, and stable heat generation characteristics are obtained. There are also advantages. In addition, although it is preferable that 1st slit S1 and 2nd slit S2 are arrange | positioned so that it may become a non-intersecting state over the whole region of the base material sheet 1, in a part of base material sheet 1, it is 1st slit S1. There is no problem even if the second slit S2 intersects.

  Although depending on the dimensions of the base sheet 1, when the heating element 1 is used for warming the body, for example, the length A1 of the first slit S1 is preferably 1 to 20 mm, particularly 3 to 15 mm. The distance B1 between the first slits S1 adjacent to each other in the first slit row L1 is preferably 0.5 to 15 mm, particularly 1 to 10 mm. The distance C1 between the adjacent first slit rows L1 is preferably 3 to 20 mm, particularly 5 to 15 mm. The same applies to the length A2 of the second slit S2, the distance B2 between the second slits S2, and the distance C2 between the second slit rows L2. However, the length A1 of the first slit S1 and the length A2 of the second slit S2 may be the same or different. The same applies to the distance B1 between the first slits S1 and the distance B2 between the second slits S2, and the distance C1 between the first slits L1 and the distance C2 between the second slits L2, and these may be the same. Or it may be different.

  When the heat generating layer is formed over the entire area of the base sheet 1, it is preferable that the first slit row L1 and the second slit array L2 are also formed over the entire area of the base sheet. On the other hand, when the heat generation layer is provided so that the surface of the base sheet is partially exposed, the first slit row L1 and / or the second slit row L2 is provided in the exposed portion. Is not required. However, it is not hindered that the first slit row L1 and / or the second slit row L2 are provided in the part. In short, it is preferable that the 1st slit row | line | column L1 and the 2nd slit row | line | column L2 are formed in the site | part in which the heat-emitting layer is formed among the base material sheets 1. FIG.

  In a heating element in which a pair of the same or different base sheet is used and a heat generating layer is formed between the pair of sheets, the slit rows L1 and L2 are formed in at least one base sheet. It is more preferable that the slit rows L1 and L2 are formed on both base sheets. Since the slit rows L1 and L2 are provided in both the base material sheets, the heating element can be made more flexible. Further, oxygen-containing gas such as air is easily supplied to the heat generating layer through the slits S1 and S2 in the slit rows L1 and L2.

  When slit rows L1 and L2 are formed on both base sheets, the positions of the slit rows L1 and L2 formed on one base sheet and the slit rows L1 and L2 formed on the other base sheet The position may be the same or different. Preferably, the slit rows L1, L2 are formed in both base sheet so as to penetrate the pair of base sheets, and the positions of the slit rows L1, L2 formed in both base sheets are the same. This is preferable from the viewpoint of further flexibility of the heating element.

  As described above, the first and second slit rows are formed on the base sheet of the heating element, and the heating layer of the heating element is at the same position as the slit row formed on the base sheet. A slit row may be formed. It is preferable that a slit row is also formed in the heat generation layer at the same position as the slit row formed in the base material sheet, since the heating element after heat generation can be made more flexible. From this point of view, in the heat generation layer, it is advantageous that the heat generation layer is divided at the positions of the slits in the slit row and the heat generation layer is continuous at the positions of the adjacent slits. At the position of each slit, the heat generating layer may be completely divided. Moreover, it is not divided completely and may be in the state connected thinly in the range which can recognize the trace in which the slit was formed visually. The thin and connected state is preferable because the heating element after the heat generation is suppressed from being cured and the heat generation characteristics of the heat generation layer are hardly impaired. This thinly connected portion can be separated by the action of an external force during use of the heating element and / or after completion of the heating, from the point that the heating element after heating can be further prevented from curing. preferable.

  Whether or not the slit rows are formed in the heat generating layer is related to the moisture content of the heat generating layer when the manufacturing method described later is adopted. When the moisture content of the heat generating layer is low, the slit rows are easily formed and held due to the high shape retention of the heat generating layer. On the other hand, when the moisture content of the heat generating layer is high, the shape retention of the heat generating layer tends to be low, so that it becomes difficult to form and hold the slit rows.

  A suitable method for producing the heating element of the present invention includes (1) a coating step, (2) an electrolyte addition step, and (3) a slit formation step. Hereinafter, each step will be described.

(1) Coating process In the coating process which is one process of a heat generating body manufacturing process, the coating material which does not contain electrolyte and contains the particle | grains of an oxidizable metal is applied to a base material sheet. The electrolyte here means an electrolyte added for the purpose of dissolving an oxide formed in the particles of the oxidizable metal, and does not mean that it does not contain any electrolyte. This means that the electrolyte added in the electrolyte addition step to be described later is substantially not included, and the chlorine component contained in the water when tap water is used is not the electrolyte referred to here. That is, when the heat generating element cannot be given a certain continuous heat generation state, it is not an electrolyte here. Since the coating material contains substantially no electrolyte, oxidation of the oxidizable metal powder does not proceed before the electrolyte addition step. Therefore, no special allowance is required in order to shield the oxidizable metal powder from the air in the coating process. In addition, the progress of the oxidation reaction during storage of the paint can be suppressed, and heat loss can be reduced. Further, since the coating material contains no electrolyte, the components of the coating material before coating or during coating maintain good dispersibility. For example, even if the paint is allowed to stand before coating, it is difficult for the oxidizable metal particles to agglomerate in the paint and the agglomerate to settle or separate. According to the present manufacturing method, as described above, since the electrolyte is not actively contained in the paint, the created paint is applied while the paint is being created in the manufacturing equipment such as a tank. In the meantime, it is difficult to cause an oxidation reaction on the wall surface of the paddle or tank of the kneading machine, and therefore, it is possible to minimize the use of expensive materials having high corrosion resistance in the manufacturing equipment.

  The paint usually contains a carbon material and water in addition to the particles of the oxidizable metal. Moreover, you may mix | blend a thickener and surfactant from a viewpoint of improving the dispersibility of the solid content in a coating material. The coating material containing these components is applied continuously or intermittently, for example, on one surface of a base sheet made of a continuous long product. Moreover, as a coating method of a coating material, various well-known coating methods can be especially used without a restriction | limiting. For example, roller coating, die coating, screen printing, roller gravure, knife coating, curtain coater, etc. are used. Using these coating methods, the paint is applied in a desired coating pattern. Die coating is preferable from the viewpoint of easy application, easy control of the coating amount, and uniform coating of the paint. Details of the coating of the heat-generating composition using the die coater are described in, for example, Japanese Patent No. 415791 related to the earlier application of the present applicant.

  The coating material used for forming the heat generating layer preferably contains 1 to 20 parts by mass, particularly 2 to 14 parts by mass of the carbon material with respect to 100 parts by mass of the oxidizable metal particles. It is preferable that the water is contained in an amount of 25 to 85 parts by mass, particularly 35 to 75 parts by mass. The thickener is preferably contained in an amount of 0.05 to 10 parts by mass, particularly 0.1 to 5 parts by mass. The surfactant is preferably contained in an amount of 0.1 to 15 parts by mass, particularly 0.2 to 10 parts by mass. Moreover, it is preferable that water is contained 18-48 mass% with respect to the whole mass of a coating material, especially 23-43 mass%. The viscosity of the paint is preferably 500 to 30,000 mPa · s, particularly 1,000 to 15,000 mPa · s at 23 ° C. and 50% RH. For measurement of the viscosity, a No. 4 rotor of a B-type viscometer was used. The measurement was performed by rotating the rotor at 6 rpm.

  By applying the paint, a coating layer is formed on one surface of the base sheet. A coating layer is a part used as the said heat generating layer by adding electrolyte later to a coating surface. When the base sheet contains particles of the superabsorbent polymer, the water contained in the paint is appropriately absorbed and retained by the superabsorbent polymer, and the water content of the coating layer is determined by the water content of the paint. Decrease than rate. As a result, the fluidity of the coating layer decreases. Further, when the base sheet contains a fiber material, this also allows the water contained in the paint to be appropriately absorbed and retained by the base sheet, thereby reducing the moisture content of the coating layer. The

  The coating is applied while sucking from the side opposite to the one side where the coating is applied on the base sheet, based on the solid content in the coating containing part of the coating and particles of oxidizable metal. It is preferable from a viewpoint of taking in between the fiber materials of a material sheet. By incorporating particles of oxidizable metal into the base sheet, the integrity of the coating layer or heat generation layer and the base sheet increases, and the heat generation layer falls off the base sheet (before use, during use, After use) is effectively prevented.

(2) Electrolyte addition step In the electrolyte addition step, which is one step of the heating element manufacturing step, the electrolyte is in a solid state on the surface of the substrate sheet after the coating is applied or on the side where the coating is applied. Add in the form of an aqueous solution. When the electrolyte is added in a solid state, the electrolyte is added separately from the oxidizable metal particles and water. When the electrolyte is added, other solid components such as capsules of scent components (except for the oxidizable metal particles) may coexist, but preferably only the electrolyte is added alone. In that case, the other solid components are blended in the paint described above. By adding the electrolyte alone, there is an advantageous effect that the dispersibility of the other solid components in the heat generating layer is improved. Further, by adding the electrolyte in a solid state, it is possible to suppress the corrosion of the device in the manufacturing process as compared with the case of adding it in an aqueous solution, and it is possible to suppress the scattering of the electrolyte to the device and / or its surroundings. Is played.

  When the electrolyte is added in a solid state, the form is not particularly limited. For example, it may be a granular material having such a size that individual particles are visible. Small particles having a size that cannot be seen with the naked eye may be used. From the viewpoint of smooth dissolution in the coating layer formed by coating the paint, it is preferable to add the electrolyte in the form of a powder (powder) as an aggregate of small particles. For example, it is preferable to add the electrolyte in the state of a powder having an average particle diameter of 50 to 1000 μm, particularly 100 to 800 μm. The average particle size can be measured, for example, by a sieving method using a standard sieve of JIS Z8801.

  As an apparatus for adding the electrolyte in a solid state, for example, a screw feeder, an electromagnetic feeder, an auger type feeder, or the like can be used. In addition, the electrolyte should just exist uniformly in a heat generating layer by the time of use of a heat generating body, and does not need to add an electrolyte uniformly with respect to a base material sheet in an electrolyte addition process.

  On the other hand, as a method of adding the electrolyte in the form of an aqueous solution, dropping or spraying with a nozzle, application with a brush, die coating, etc. are used, but scattering of the aqueous electrolyte solution to the surroundings, prevention of clogging of the aqueous electrolyte solution outlet, paint From the viewpoint of preventing contamination of the production equipment due to contact with the nozzle, it is preferable to drop or spray the nozzle with a nozzle. The concentration of the electrolyte is adjusted so that the moisture content of the heat generating layer falls within an appropriate range and the flow state of the heat generating layer becomes appropriate.

  Whether the electrolyte is added in a solid state or in the form of an aqueous solution, the amount of the electrolyte added is 100 parts by mass per unit area of the oxidizable metal particles. The content is preferably 0.5 to 15 parts by mass, particularly 1 to 10 parts by mass.

  By adding the electrolyte to the coating layer, a target heat generation layer is formed. When forming a heat generating layer on each surface of the substrate sheet, the above operation may be performed on the other surface of the substrate sheet. Further, when the heat generating layer is formed only on one surface of the base sheet, prior to performing the slit forming step (3) described below, the heat generating layer is made of a continuous long object. A step of supplying the second base sheet and superimposing the second base sheet on the heat generating layer may be performed. By performing this process, a heating element provided with a heating layer between two identical or different base material sheets can be easily manufactured.

(3) Slit formation process In a slit formation process, the 1st slit row | line | column which consists of a some 1st slit is formed in multiple rows with respect to one base material sheet or a pair of base material sheet. At the same time, a plurality of second slit rows each including a plurality of second slits extending in a direction intersecting with the extending direction of the first slit rows are formed. The slits of the first slit row and the second slit row are formed by using a cutting blade and allowing the cutting blade to enter the base sheet and the heat generating layer.

  For example, when the slit sheet is continuously formed in the base sheet while the base sheet on which the heat generation layer is formed is transported in one direction, first, the first slit array extends in the same direction as the transport direction. Then, it is preferable to form the second slit row so as to extend in a direction crossing the transport direction. Forming the slit rows in this order is advantageous in that the substrate sheet can be stably conveyed and positional deviation in the conveyance direction can be suppressed as much as possible. In this case, a slitter using a generally known round blade may be used to form the first slit row. On the other hand, for forming the second slit row, a generally known rotary cutter, that is, a cutter having a plurality of rows of blades provided intermittently along the rotation axis direction of the roll in the rotation direction of the roll. A roll may be used. Whatever means is used to form the slit row, each of the first slit constituting the first slit row and the second slit constituting the second slit row is in a non-intersecting state. It is preferable to form a slit.

  When one base sheet is used and a heat generating layer is formed on one surface of the base sheet, the formation of slit rows on the base sheet can be performed by entering a cutting blade from the heat generating layer side. preferable. In this case, it is possible to form a slit row more smoothly by forming a slit by making the cutting blade enter the heat generating layer while performing suction from the surface of the base sheet where the heat generating layer is not formed. It is preferable because it is possible. When a pair of base material sheets is used and a heat generation layer is formed between both base material sheets, the cutting blade may enter from either base material sheet side. By performing the approach of the cutting blade so as to penetrate the two base material sheets, it is possible to form a slit row in the same pattern at the same position of the two base material sheets.

  In the formation of the first and second slit rows, it is preferable that the previously formed heating layer has fluidity. By forming both slit rows while the heat generating layer is fluid, even if the cutting blade penetrates the heat generating layer when forming both slit rows, the heat generating layer is removed when the cutting blade is removed from the heat generating layer. Because of having fluidity, the heat generating layer is easily restored to the state before the cutting blade enters. However, the heat generation layer after the cutting blade has entered is in a range where the traces of the slits can be visually recognized at the site where the cutting blade has entered, rather than being completely restored to the state before the cutting blade has entered. Thus, it is preferable that the connection is thinner than other portions because the heat generation characteristics of the heat generation layer are less likely to be impaired while curing of the heat generating element after heat generation is suppressed. When the fluidity of the heat generation layer is low, the state of the slit formed by the cutting blade entering the heat generation layer is easily maintained.

  In this way, the intended heating element is obtained. After the heating element is manufactured, a heating element covering and sealing step can be performed as an additional process to manufacture a heating tool having the heating element. In the heating element covering and sealing step, the heating element is covered with a packaging material. When a heating element is manufactured continuously and a heating element made of a continuous long object is manufactured, the heating element made of a continuous long object is cut in the width direction prior to the heating element covering and sealing step. It is preferable to produce a heating element for each leaf.

  When one base sheet is used and a heat generating layer is formed on one surface of the base sheet, the side on which the heat generating layer is formed while the heating elements of each leaf run in one direction at a predetermined interval In addition, a first covering sheet made of a continuous long object is disposed on the other side, and a second covering sheet also made of a continuous long object is disposed on the other side. When a heating element is manufactured using a pair of base sheets, the first cover sheet is disposed outside one of the two base sheets, and the same is placed outside the other sheet. The 2nd coating sheet which consists of a continuous long thing is arrange | positioned. Subsequently, the extension area | region from the heat generating body in a 1st coating sheet and a 2nd coating sheet is joined by a predetermined joining means. Joining is performed outside the left and right side edges and outside the front and rear edges of the heating element. Examples of the bonding means include heat fusion, ultrasonic bonding, and adhesion using an adhesive.

  In this manner, a continuous long object in which a plurality of heating tools are connected in one direction is obtained. By cutting this continuous long object across the width direction between adjacent heating elements, the intended heating tool is obtained. In the next step, the heating tool is hermetically housed in a packaging bag having oxygen barrier properties.

  In this production method, it is preferable to keep the production line in a non-oxidizing atmosphere in order to suppress oxidation of the oxidizable metal in the production process, particularly in the step after the electrolyte addition step.

  In the above manufacturing method, prior to the heating element covering and sealing step, the heating element made of a continuous long object was cut across its width direction, but instead, the coating layer was formed prior to the electrolyte addition step. The formed base sheet made of continuous long material may be cut, and the electrolyte may be added to the base sheet that has become a leaf in the electrolyte addition step.

  Moreover, in the above manufacturing method, after coating the base material sheet to form a coating layer, an electrolyte was added to the coating layer, but instead, the electrolyte was first applied to the base material sheet. It may be added in the solid state or in the state of an aqueous solution, and then the paint may be applied. Alternatively, a heat generating layer may be formed in one step by preparing a paint containing particles of an oxidizable metal, a carbon component, water and an electrolyte, and applying the paint to a base sheet.

  FIG. 2 shows an example of an apparatus preferably used in the manufacturing method. The apparatus includes a coating coating unit 10, an electrolyte addition unit 20, a slit forming unit 30, a first cutting unit 40, a re-pitch unit 50, a covering unit 60, a sealing unit 70, and a second cutting unit 80.

  The coating unit 10 includes a die coater 11. Moreover, the endless belt 12 of the wire mesh which opposes the die lip of the die coater 11 and circulates in the arrow direction is also provided. The base sheet 1 made of a continuous long material fed from the base roll 1A of the base sheet is conveyed by an endless belt 12, and a coating is applied to one surface of the base sheet 1 by a die coater 11, and a coating layer 100A. Is formed. The coating unit 10 may further include a suction box (not shown) facing the die lip of the die coater 11 with the endless belt 12 interposed therebetween. When the coating unit 10 includes a suction box, the suction box is operated when the base sheet 1 is transported by the endless belt 12, the transport is stabilized, and the base material sheet 1 is stably held by sucking the paint. be able to.

  The electrolyte adding unit 20 includes an adding means 21 (nozzle 21) for adding an electrolyte. Moreover, the wire mesh endless belt 12 which opposes the opening part of the nozzle 21 and circulates in the arrow direction is also provided. The base material sheet 1 after the coating is applied is conveyed from the coating unit 10 to the electrolyte adding unit 20 by the endless belt 12, and the nozzle of the nozzle 21 toward the coating layer 100 </ b> A of the base material sheet 1. The electrolyte is added from the holes in a solid state or an aqueous solution state, and the heat generating layer 100B is formed. By adding the electrolyte after applying the paint, the concentration of the electrolyte suitable for heat generation can be ensured in the heat generating layer 100B, and the electrolyte depends on the moisture contained in the coating layer 100A and the base sheet 1. As the concentration is diluted, the substrate sheet 1 absorbs and retains the moisture content and the electrolyte concentration of the heat generating layer 100B. The electrolyte addition unit 20 may further include a suction box (not shown) facing the opening of the nozzle 21 with the endless belt 12 interposed therebetween. By providing the electrolyte addition unit 20 with the suction box, the conveyance of the base sheet 1 in the electrolyte addition unit 20 can be activated to stabilize the conveyance. In addition, the suction of the suction box during the addition of the electrolyte facilitates the penetration of the electrolyte into the base sheet 1.

  For the base sheet 1 on which the heat generating layer 100B is formed, the base sheet 1 'made of a continuous long material is supplied onto the heat generating layer 100B. The base sheet 1 'is overlaid on the heat generating layer 100B. As a result, a continuous long body of the heating element provided with the heating layer 100B is formed between two identical or different base material sheets 1 and 1 '.

  In the slit forming unit 30, the first slit row and the second slit row are formed on the continuous elongated object. The continuous long object 100C of the heating element is conveyed in one direction D as shown in FIG. 3 (a), and the first slit forming device 31 moves the continuous long object 100C in the conveyance direction D with respect to the continuous long object 100C. Along the first slit rows L1, multiple rows are formed. Since the continuous long object 100 </ b> C includes a pair of base sheet 1, a cutting blade (not shown) provided in the first slit forming device 31 is used for both the pair of base sheets 1. And the first slit row is formed in the same pattern at the same position on both base sheet 1.

  The slit forming unit 30 is also provided with a second slit forming device 32. The second slit forming device 32 is disposed downstream of the first slit forming device 31. The continuous long object 100C after the first slit row L1 is formed is processed by the second slit forming device 32 and extends in a direction intersecting the transport direction D as shown in FIG. A plurality of slit rows L2 are formed in the continuous long object 100C. In the figure, the second slit row L2 is formed to extend in a direction orthogonal to the transport direction.

  When the first slit row L1 and the second slit row L2 are formed, the heat generating layer 100B of the continuous long object 100C preferably has fluidity. In order to do this, the water absorption of the base sheet 1, the amount of water in the coating material, the mode of addition of the electrolyte (solid or aqueous solution) and the like may be appropriately controlled.

  In this way, the continuous long object 100 </ b> C of the heating element in which the slit row is formed is cut in the first cutting part 40 in the width direction. The first cutting unit 40 includes a rotary die cutter 42 and an anvil roller 43. Cutting is performed by the continuous long object 100C passing between both members, whereby a heating element 100D for each leaf is obtained.

  The continuous long object 100C of the heating element may be cut so as to extend in the width direction of the continuous long object 100C. For example, the continuous long object 100C can be linearly formed in the width direction of the continuous long object 100C. Or it can cut so that a cutting line may draw a curve. In any case, it is preferable to employ a cutting pattern that does not cause trimming by cutting, but it may be cut into a desired shape such as an ellipse or streamline.

  The heating element 100D that has become a leaf is changed in pitch in the front and rear in the transport direction in the re-pitch portion 50, and the heating elements 100D that are adjacent to each other are rearranged at a predetermined distance. As such a re-pitch mechanism, a conventionally known one can be used without particular limitation.

  The re-pitched heating element 100D is transported to the covering section 60, and is entirely covered by the first covering sheet 4 made of a continuous long object and the second covering sheet 5 also made of a continuous long object. When one base sheet is used and the heat generating layer 100B is formed on one surface of the base sheet, the first covering sheet 4 covers the side of the heat generating body 100D where the heat generating layer 100B is formed, The second covering sheet 5 covers the side of the heating element 100D where the heating layer 100B is not formed. The heating element 100 </ b> D is introduced into the sealing portion 70 while maintaining this covering state. The sealing part 70 includes a first roller 71 having a seal convex part 72 and a second roller 73 having the seal convex part 72. The rollers 71 and 73 are arranged in such a positional relationship that the axial directions thereof are parallel to each other and the seal convex portions 72 of the rollers 71 and 73 are in contact with each other or a predetermined clearance is generated therebetween. ing. In the sealing part 70, the extension part of the 1st and 2nd coating sheets 4 and 5 extended from front, back, left, and right of the heating element 100D is joined by heat sealing. This joining is, for example, a continuous airtight joining surrounding the heating element 100D.

  In this manner, a continuous long object in which a plurality of heating tools are connected in one direction is obtained. The continuous long object is cut in the width direction in the second cutting portion 80. The second cutting unit 80 includes a rotary die cutter 82 having a cutter blade 81 on the peripheral surface and an anvil roller 83. Cutting is performed by passing the continuous long object between the two members, whereby the intended heating tool 100 is obtained. In the cutting, when the cutting line of the continuous long object 100C in the first cutting unit 40 described above is, for example, a straight line, it is preferable that the cutting line in the main cutting unit 80 is also a straight line. Moreover, when the cutting line of the continuous long object 100C in the 1st cutting part 40 is a curve, it is preferable that the cutting line in this cutting part 80 is also a curve which followed it.

  As shown in FIG. 4, the heating tool 100 obtained in this way is entirely surrounded by a heating material 100 </ b> D with a packaging material 6 including a first covering sheet 4 and a second covering sheet 5. When one base sheet is used and a heat generating layer is formed on one surface of the base sheet, the heating tool 100 is disposed on the side of the surface on which the heat generating layer 100C, which is one surface of the heat generating element 100D, is formed. The second cover sheet 5 is disposed on the side of the surface on which the first cover sheet 4 is disposed and the heat generating layer which is the other surface is not formed.

A part of the first covering sheet 4 in the packaging material 6 has air permeability or the whole has air permeability. The air permeability of the first cover sheet (JIS P8117 B type, hereinafter referred to as the measured value of this method when referred to as air permeability) is 1 to 50,000 seconds / (100 ml · 6.42 cm ² ), particularly 10 to 40. 000 seconds / (100 ml · 6.42 cm ² ). As the first covering sheet having such air permeability, for example, a porous sheet made of a synthetic resin having moisture permeability but not water permeability is preferably used. When such a porous sheet is used, various fiber sheets including a nonwoven fabric such as a needle punch nonwoven fabric and an air-through nonwoven fabric are laminated on the outer surface of the porous sheet (the surface facing the outside in the first covering sheet 4). Then, the texture of the first cover sheet 4 may be enhanced.

As the second covering sheet 5 in the packaging material 6, an appropriate one is selected according to the structure of the heating element. The second cover sheet 5 is preferably a sheet having lower air permeability than the first cover sheet 4 from the viewpoint of stably generating water vapor through the first cover sheet 4. In particular, when the heating layer 100 </ b> C of the base sheet 1 is not located on the second covering sheet 5 side, the second covering sheet 5 is a sheet having a lower air permeability than the first covering sheet 4. Preferably there is. The “low-breathable sheet” as used herein refers to a non-breathable sheet that is partially breathable but has a lower breathability than the first covering sheet 4 and has no breathability. Includes both cases. When the second cover sheet 5 is a non-breathable sheet, the non-breathable sheet may be a synthetic resin film or a needle punch on the outer surface of the film (the surface facing the outside in the second cover sheet 5). A composite sheet obtained by laminating various fiber sheets including a nonwoven fabric such as a nonwoven fabric or an air-through nonwoven fabric can be used. When the second cover sheet 5 is a breathable sheet, the same breathable sheet as that of the first cover sheet 4 can be used. In this case, the air permeability of the second cover sheet 5 is 200 to 150,000 seconds / (100 ml · 6.42 cm ² ), particularly 300 to 1 on the condition that the air permeability of the first cover sheet 4 is lower than that of the first cover sheet 4. It is preferably 100,000 seconds / (100 ml · 6.42 cm ² ). When the second cover sheet 5 is a breathable sheet, stable heat generation can be performed even in a use state in which the outer surface of the first cover sheet 4 is in close contact with the user's skin or clothes, for example.

  It is preferable that the heating tool 100 can generate water vapor from the side where the first cover sheet 4 is disposed. In order to enable the generation of water vapor, (B) a method of adjusting the ratio of each component constituting the heat generating layer 100C on the assumption that the heat generating layer 100C contains a large amount of water; C) A method of adjusting the air permeability of the first and second cover sheets 4 and 5 surrounding the heating element 100D, a method of using (D), (B) and (C) in combination. When base material sheet 1 contains hydrophilic fibers, when a large amount of water can be retained, heating tool 100 can generate a large amount of water vapor. In the case where the base sheet 1 also contains a superabsorbent polymer in addition to containing hydrophilic fibers, the base sheet 1 can also retain a large amount of water due to this, as a result, A large amount of water vapor can be generated.

  When both the first covering sheet 4 and the second covering sheet 5 have air permeability, the air permeability value of the first covering sheet 4 is smaller than the air permeability value of the second covering sheet 5. Therefore, the amount of water vapor released through the first cover sheet 4 is set to be larger than the amount of water vapor released through the second cover sheet 5. Is preferred. As long as the amount of water vapor released through the first cover sheet 4 is larger than the amount of water vapor released through the second cover sheet 5, water vapor is released through the second cover sheet 5. Is not disturbed at all.

  For example, the heating tool 100 is applied directly to the human body or applied to clothing, and is suitably used for warming the human body. Examples of the application site in the human body include the shoulder, neck, face, eyes, waist, elbow, knee, thigh, lower leg, abdomen, lower abdomen, hands, and soles. Further, in addition to the human body, the present invention is applied to various articles and suitably used for heating and keeping warm.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to this embodiment. For example, in the embodiment shown in FIG. 1, the first slit S1 along the flow direction of the heating element 1 and the second slit S2 orthogonal to the first slit S2 are formed. ), The third slit S3 and the fourth slit S4 inclined with respect to the flow direction MD of the heating element 1 may be formed. The third slit S3 and the fourth slit S4 may be orthogonal to each other.

  Further, the direction of the slit rows is not limited to two different directions, and slit rows of three or more different directions may be formed. For example, the embodiment shown in FIG. 1 and the embodiment shown in FIG. 5A can be combined to arrange the slits in the pattern shown in FIG. In the embodiment shown in FIG. 5 (b), the first slit S1 along the flow direction of the heating element 1 and the second slit S2 perpendicular to the first slit S2 are formed and inclined with respect to the flow direction MD of the heating element 1. The third slit S3 and the fourth slit S4 are formed. The position of the intersection of the slit array of the first slit S1 and the slit array of the second slit S2 coincides with the position of the intersection of the slit array of the third slit S3 and the slit array of the fourth slit S4.

  2 and 3, the first slit row L1 and the second slit row L2 are sequentially formed. Instead, both the slit rows L1 and L2 are formed at the same time. May be. In that case, a rotary cutter in which blades are formed in the axial direction and the circumferential direction may be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” and “part” mean “% by mass” and “part by mass”, respectively.

[Example 1]
(1) Preparation of paint and aqueous electrolyte solution As paint, 100 parts of oxidizable metal (iron powder average particle size 45 μm), 8 parts of carbon material (activated carbon average particle size 42 μm), 0.2 part of thickener (gua gum), What mixed 70 parts of water was used. The viscosity of the obtained paint was 15,000 mPa · s. The viscosity was measured using a B-type viscometer No. 4 rotor in an environment of 23 ° C. and 50% RH.

(2) Preparation of base sheet The base sheet was produced according to the method described in JP-A-8-246395. In this base sheet, sodium polyacrylate-based superabsorbent polymer particles are mainly present in a substantially central region in the thickness direction of the base sheet, and the particles are substantially present on the surface of the base sheet. One sheet (one ply) having a structure that does not exist. The base sheet has a layer of hydrophilic cross-linked bulky cellulose fibers on the front and back with the site where the superabsorbent polymer particles are present. The layer of crosslinked bulky cellulose fibers further contained softwood bleached kraft pulp and paper strength enhancer (PVA). A superabsorbent polymer having an average particle size of 340 μm was used. The basis weight of each layer was 30 g / m ² and 20 g / m ² . The basis weight of the superabsorbent polymer particles was 50 g / m ² . Therefore, the basis weight of the base sheet was 100 g / m ² .

(3) Production of Heating Element and Heating Tool Using the apparatus shown in FIG. 2, a heating element was produced according to the production method described above. The paint was continuously applied to one surface of the base sheet made of a continuous long material having a width of 50 mm. The coating basis weight of the paint was 1,800 g / m ² . An electrolyte (sodium chloride) was sprayed as a powder toward the surface on which the paint was applied (coated surface) to form a heat generating layer. When the electrolyte was added, suction from the non-coated surface side of the base material sheet was not performed. The spraying basis weight of the electrolyte was 35 g / m ² . Next, a first slit row extending in the conveyance direction of the base sheet was formed by a slit forming device, and then a second slit row extending in a direction orthogonal to the first slit row was formed. The first and second slit rows were formed while the heat generating layer had fluidity. The length of the slits constituting the first and second slit rows was 3 mm. The distance between adjacent slits in the first and second slit rows was 1 mm. Furthermore, the distance between the adjacent first slit rows was 10 mm. The distance between adjacent second slit rows was 10 mm. The continuous heating element thus obtained was cut in the width direction to obtain a heating element of 50 mm × 50 mm per leaf. After covering the entire heating element of each leaf with the first covering sheet and the second covering sheet, the extending portions of the first and second covering sheets extending from the front, rear, left and right of the heating element, Joined by heat sealing. This joining was a continuous airtight joining surrounding the heating element. The seal width was 5 mm. In this way, a heating tool 100 having the structure shown in FIG. 4 was obtained. A polyethylene porous sheet having a basis weight of 50 g / m ² and an air permeability of 20,000 s / (100 ml · 6.42 cm ² ) was used as the first cover sheet. As the second covering sheet, a polyethylene porous sheet having a basis weight of 50 g / m ² and an air permeability of 80,000 s / (100 ml · 6.42 cm ² ) was used. Each covering sheet was a 65 mm × 65 mm rectangle.

[Comparative Example 1]
In Example 1, only the first slit row was formed in the heating element, and the second slit row was not formed. Except this, it carried out similarly to Example 1, and obtained the heating tool.

[Comparative Example 2]
In Example 1, neither the first slit row nor the second slit row was formed in the heating element. Except this, it carried out similarly to Example 1, and obtained the heating tool.

[Evaluation]
About the heating tool obtained by the Example and the comparative example, the time change of the three-point bending load was measured with the following method. The result is shown in FIG.

[Time change of three-point bending load]
The heating tools obtained in the examples and comparative examples were brought into contact with air to generate heat. The three-point bending load of the heating tool was measured every predetermined time from the start of contact with air, and the relationship between the three-point bending load and time was plotted on a graph. The three-point bending load is measured as follows. The measuring instrument is Tensilon Universal Tester RTA-500 manufactured by ORIENTEC. As shown in FIGS. 6A and 6B, the heating tool 100 is bridged between a pair of plate-like supports 90 and 90 having a width of 6 mm. There are two types of methods, i.e., the method of making the direction coincide with the width direction (CD) of the heating element and the method of making the direction of the extension me coincide with the running direction (MD) of the heating element. It was adopted. The interval between the supports 90 is 25 mm. Further, the length of the support 90 is made longer than the length of the heating tool 100. The plate-like pusher 91 is lowered at a rate of 100 mm / min from the top of the heating tool 100 spanned between the supports 90, and the heating tool 100 is pushed in. The plate-like pusher 91 has a width of 1.5 mm and a length longer than the length of the heating tool 100. The position where the plate-like pusher 91 is pushed in is an intermediate position between the pair of supports 90. The plate-like push-in body 91 is pushed into the support 90 by 15 mm, and the maximum value of the load generated during the movement amount is defined as a three-point bending load.

  As is clear from the results shown in FIG. 7, the heating tool obtained in Example 1 has three points in both the width direction (CD) and the running direction (MD) compared to the heating tool obtained in the comparative example. It can be seen that the bending load has little change over time and the hardness is reduced. On the other hand, in Comparative Example 1, only the width direction (CD) has the same hardness as the Example, but the traveling direction (MD) becomes harder with heat generation as in Comparative Example 2. Although not shown in the figure, the heating tools obtained in the examples and comparative examples all have almost the same heating characteristics, and no significant difference was found.

1,1 'base material sheet 100A coating layer 100B heat generating layer 100C continuous long object of heat generating element 100D heat generating element 100 heat generating tool S1 first slit S2 second slit L1 first slit array L2 second slit array

Claims (15)

A layer of a heat generating composition containing particles of an oxidizable metal, a carbon component, water and an electrolyte is a method for producing a heating element provided on one surface of a base sheet,
After forming the layer of the exothermic composition on one surface of the base sheet, the base sheet has a step of forming a plurality of first slit rows and a plurality of second slit rows,
The first slit row is composed of a plurality of slits arranged to extend in one direction,
The second slit row is a method for manufacturing a heating element, comprising a plurality of slits arranged so as to extend in one direction in a direction intersecting the first slit row.   On one surface of the substrate sheet, a paint layer that does not contain the electrolyte and contains particles of the oxidizable metal is applied to form a paint layer, and then the electrolyte is applied to the paint layer in a solid state or in an aqueous solution state The manufacturing method according to claim 1, wherein the exothermic composition layer is formed by adding in a step.   The manufacturing method of Claim 1 or 2 which forms each slit so that the slit in a 1st slit row | line and the slit in a 2nd slit row | line | column may be in a non-cross | intersecting state.   The manufacturing method according to any one of claims 1 to 3, wherein the plurality of slits are formed by using a cutting blade and causing the cutting blade to enter the base sheet and the layer of the heat generating composition. On the layer of the exothermic composition, the same or different base sheet as the base sheet is stacked,
The manufacturing method according to any one of claims 1 to 4, wherein each of the slits is formed so as to penetrate both the base material sheets.   While the base sheet is conveyed in one direction, a first slit row is formed so as to extend in the same direction as the conveyance direction, and then a second slit row is formed so as to extend in a direction crossing the conveyance direction. The manufacturing method as described in any one of Claim 1 thru | or 5.   While the base sheet is conveyed in one direction, a first slit row is formed to extend in the same direction as the conveyance direction, and then a second slit row is formed to extend in a direction orthogonal to the conveyance direction. The manufacturing method according to claim 6.   The manufacturing method as described in any one of Claims 1 thru | or 7 using what has water absorption as the said base material sheet.   The manufacturing method of Claim 8 which uses a fiber sheet as the said base material sheet.   The production method according to claim 8 or 9, wherein a fiber sheet containing particles of a superabsorbent polymer and a fiber material is used as the base sheet. On one surface of the base sheet, a layer of a heat generating composition containing particles of an oxidizable metal, a carbon component, water and an electrolyte is provided,
The base sheet is formed with a plurality of first slit rows composed of a plurality of slits arranged so as to extend in one direction, and extends in one direction toward a direction intersecting the first slit row. A plurality of second slit rows composed of a plurality of slits arranged in such a manner,
A heating element in which each slit is arranged so that the slit in the first slit row and the slit in the second slit row are in a non-intersecting state. A layer of the exothermic composition is provided between the same or different pair of substrate sheets,
The heating element according to claim 11, wherein each of the slits is formed so as to penetrate the pair of base material sheets.   The heating element according to claim 11 or 12, wherein the first slit row and the second slit row are orthogonal to each other.   The heating element according to any one of claims 11 to 13, wherein the base sheet has water absorption.   The heating element according to claim 14, wherein a fiber sheet is used as the base sheet.