JP5766085B2 - A method for manufacturing a heating element. - Google Patents

Description

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

  A heating tool having a heating element utilizing an oxidation reaction of an oxidizable metal tends to become harder as the oxidation of the oxidizable metal 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. For the purpose of obtaining a flexible heating element, for example, it has been proposed to form irregularities on the surface layer portion of a layer of a heating composition formed on a substrate (see, for example, Patent Document 1).

  However, in this document, since the embossed pattern roll is used for forming the irregularities, the concave portions are easily consolidated, and it is not easy to impart sufficient flexibility. Also, heat generation failure is likely to occur due to consolidation. Furthermore, since the layer of the exothermic composition is creamy, the exothermic composition tends to adhere to the embossed pattern roll, and the roll is easily contaminated.

  Apart from the technique described in Patent Document 1, the present applicant firstly has a sheet-like heating element in which notches extending in one direction are formed in multiple lines, or a large number of embossments are formed in the form of dots. Proposed (see Patent Document 2). The sheet-like heating element is easily deformed by this cut and emboss. Therefore, the heating tool provided with the sheet-like heating element is deformed so as to conform to the curved shape of the body including the face, and the fitting property is improved, and the usability is good. However, manufacturing a sheet-shaped heating element complicates the process as compared to manufacturing a heating element by forming a layer of a heating composition on a base sheet.

JP-A-10-263002 JP 2009-82570 A

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

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 substrate sheet having water absorption,
While the substrate sheet is traveling in one direction, a coating layer is formed on one surface of the substrate sheet by applying a coating containing at least the oxidizable metal particles, and then the coating layer is in a fluid state The lower end of the rod-shaped body is brought into contact with the coating layer to scrape off part of the coating layer to form a streak-like recess extending in the same direction as the running direction of the base sheet. The present invention provides a method for manufacturing a heating element.

  According to the present invention, the surface of the layer can be easily made uneven without imposing a load on the layer of the exothermic composition.

FIG. 1A to FIG. 1C are schematic views showing the formation of recesses using a rod-like body over time. FIG. 2A is a schematic view of a formation state of a recess using a rod-like body as viewed from the front, and FIG. 2B is a schematic view of the formation state of a recess using a rod-like body in a plan view. FIG. 3 is a schematic diagram showing another example of the formation of the concave portion using the rod-shaped body. 4A to 4C are schematic views showing examples of rod-shaped bodies. FIG. 5 is a schematic view showing an apparatus suitably used in the production method of the present invention. FIG. 6A is a schematic diagram showing a partially broken heating element manufactured using the apparatus shown in FIG. 5, and FIG. 6B is a cross-sectional view taken along the line bb in FIG. 6A. FIG. FIG. 7 is a longitudinal sectional view of a heating tool manufactured using the apparatus shown in FIG.

  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. Or a heat generating body has the same or different base material sheet, and the heat generating layer provided between both base material sheets.

  When the heating element has a configuration having one base sheet and a heat generating layer provided on the base sheet, the surface layer portion of the heat generating layer is uneven. On the other hand, when the heating element has a pair of base material sheets and a heat generation layer provided between them, the surface of the heat generation layer is in contact with one of the base material sheets. Unevenness is formed on the surface layer of the surface. In any case, the unevenness is formed in a streaky pattern and alternately so as to extend in one direction. The concave portion provided in the surface layer portion on one surface of the heat generating layer is a portion recessed toward the other surface side of the heat generating layer, and the convex portion is a portion between adjacent concave portions.

  The concave portion and the convex portion extending in a line shape may be, for example, linear. Alternatively, it may be a mountain-shaped waveform or a curved waveform. Moreover, the recessed part and the convex part may be continuous over the extending direction, or may be intermittent. The depth of the recess may be the same over the extending direction of the recess, or may vary regularly or irregularly. The widths of the recesses and the protrusions may be the same in the direction in which they extend, or may vary regularly or irregularly.

  Furthermore, the heat generating layer may be formed with a first recess extending in the first direction and a second recess extending in the second direction intersecting the first direction in the surface layer portion. By doing so, the flexibility of the heating element can be further increased as compared with the case where the recess is formed only in one direction. From the viewpoint of making the flexibility even more remarkable, it is preferable to set the crossing angle between the first direction and the second direction to 45 degrees or more. In particular, it is preferable that the first direction and the second direction are orthogonal from the viewpoint of developing substantially the same flexibility in any direction in the plane of the heating element. The term “perpendicular” here refers not only to the case where the two directions intersect at 90 degrees, but also to the two directions unavoidably due to manufacturing conditions and fluctuations in the manufacturing apparatus in the heating element manufacturing method described later. This includes the case where the crossing angle of fluctuates slightly from 90 degrees. In the following description, the term “orthogonal” is also used in this sense.

  As described above, according to this production method, the coating layer can be applied by a simple method of partially scraping the coating layer with a rod-like body without adopting advanced coating techniques such as stripe coating and pattern coating. There is an advantage that the layer can be formed in a predetermined shape.

  When the recesses are formed in two different directions, the depth of the recesses is made the same as the thickness of the heat generation layer, that is, the depth of the recesses is 100% with respect to the thickness of the heat generation layer. The base sheet may be exposed in step (b). By carrying out like this, each convex part will be in the state where the circumference was surrounded by the surface of the exposed base material sheet, and was divided individually independently. By forming such a convex part, the flexibility of the target heating element can be further enhanced. If the base sheet has sufficient strength, the base sheet will not be seriously damaged even if the heating layer is scraped off so that the base sheet is exposed.

  Regardless of the form of the heating element, the thickness of the heating layer is generally 0.1 to 5 mm, particularly 0.2 to 3 mm, to ensure sufficient heat generation characteristics and sufficient flexibility. From the viewpoint of From the viewpoint of flexibility, the depth of the recess is preferably 50% or more, particularly 60% or more, with respect to the thickness of the heat generating layer. On the other hand, it is preferable from the viewpoint of the continuity of the exothermic reaction that the surface of the base material sheet is not exposed at the bottom of the recess. From this viewpoint, the depth of the recess is preferably 90% or less, particularly 80% or less, with respect to the thickness of the heat generating layer. The thickness of the heat generating layer is measured with reference to the surface of the base sheet. Therefore, even when the base sheet is made of a porous material such as a nonwoven fabric and a part of the heat generating layer has entered the base sheet, the thickness of the heat generating layer is determined by the surface of the base sheet. Measure as a reference. The measurement method is preferably thickness measurement using a laser displacement meter. By this measurement method, the thickness of the heat generating layer in the width direction can be measured, and not only the thickness of the concave and convex portions can be measured simultaneously, but also coating defects such as coating stripes and air bites can be detected.

  The width of the concave portion and the convex portion (the width in the direction orthogonal to the direction D in FIG. 2B) may be the same, but the width of the convex portion is larger than the width of the concave portion to obtain sufficient heat generation characteristics. And from the viewpoint of reducing the load applied to the layer of the exothermic composition when forming the recess. The width of the recess (the width in the direction perpendicular to the direction D in FIG. 2B) is preferably 0.5 to 5 mm, and particularly preferably 1 to 3 mm. Moreover, it is preferable that the width | variety of a convex part (width of the direction orthogonal to the direction D of FIG.2 (b)) is 0.5-50 mm, and it is especially preferable that it is 5-30 mm. The ratio of the width of the concave portion to the width of the convex portion (the width of the concave portion / the width of the convex portion) is preferably 0.01 to 1, and particularly preferably 0.1 to 0.5.

  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 to be described later, and a part of solids 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.

  The heat generating layer preferably contains particles of an oxidizable metal, a carbon component, water, and an electrolyte. 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 range described later, the amount of the oxidizable metal in the heating element is 100 to 3,000 g / m ² , particularly 200 to 1,500 g / in 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 .

  The heat generating layer is preferably in a water-containing state. The moisture content of the heat generating layer is preferably 5 to 40% by mass, particularly 6 to 35% by mass. 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.

  Examples of the base sheet on which the heat generating layer is formed include a fiber sheet, a synthetic resin film, and a laminate 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 particles of superabsorbent polymer and hydrophilic fibers. This fiber sheet is produced by, for example, a wet papermaking method or a dry papermaking method. 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 the hydrophilic fiber contained in the fiber sheet, any of natural fiber and 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.

  As described above, the base sheet made of the fiber sheet preferably 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.

  Further, at the time of scraping, from the viewpoint of having sufficient strength against the rod-shaped body, a synthetic resin film, a laminate of the film and the fiber sheet, a fiber sheet with increased strength, etc. are used as the base sheet. be able to. In order to increase the strength of the fiber sheet, it is preferable to increase the basis weight, blend heat-fusible fibers, or perform a calendar process.

  As described above, the preferred method for producing the heating element includes (1) a coating process, (2) a recess forming process, and (3) an electrolyte adding process. Hereinafter, each step will be described.

  In the coating process, which is one process of manufacturing the heating element, a coating material that does not contain an electrolyte and contains particles of an oxidizable metal is applied to the base 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. Regardless of the method used to form the coating layer, the surface of the coating layer can be formed flat, so that the recess can be successfully formed in the recess forming step (2), which is the next step. It is preferable from the point. In the present specification, the term “coating layer” means not only a layer formed by applying a paint containing (A) oxidizable metal particles but not containing an electrolyte. B) A layer in which an electrolyte is added to a layer formed by applying a paint containing an oxidizable metal but not an electrolyte, and (C) both an oxidizable metal particle and an electrolyte. It also means a layer formed by applying a paint containing. The layers (B) and (C) are heat generating layers.

  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 However, if the moisture content of the coating layer is excessively decreased, the fluidity is excessively decreased, so that it may be difficult to form the recesses in the recess forming step (2) as the next step. From this viewpoint, in the state before being subjected to the recess forming step of (2), the moisture content of the coating layer is such that the moisture content of the coating layer is 10 to 48 mass%, particularly 20 to 43 mass%, It is preferable to adjust the water absorption of the base sheet. The moisture content of the coating layer is measured in the same manner as the measurement of the moisture content of the heat generating layer described above.

  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 substrate sheet, the integrity of the coating layer and the substrate sheet is increased, and the exothermic layer is removed from the substrate sheet (before, during, and after use). Is effectively prevented.

(2) Concave formation step When the coating layer is formed in this way, the rod-shaped body is approached from the surface side of the coating layer, and the lower end of the rod-shaped body is caused to enter the coating layer. This operation is advantageously performed while the coating layer is in a fluid state. The fluidized state is, for example, a state in which the moisture content of the coating layer is within the above-described range, and means that the coating layer has a viscosity that can be changed into an indefinite shape by the action of an external force. Thus, with the lower end of the rod-shaped body in contact with the coating layer, the coating layer and the rod-shaped body are relatively moved to scrape off a part of the coating layer and extend in the same direction as the moving direction. A streak-like recess is formed. When relatively moving the coating layer and the rod-shaped body, for example, (a) a method in which the rod-shaped body is fixed and the base sheet including the coating layer is run in one direction, (b) coating Adopting a method of moving the rod-shaped body in one direction while fixing the substrate sheet including the layer, (c) a method of moving the substrate sheet including the coating layer and the rod-shaped body in directions opposite to each other by 180 degrees, etc. can do. In the coating step (1) described above, when the coating layer is formed on the base sheet traveling in one direction, it is preferable to adopt the method (a) as a continuation thereof.

  When the coating layer is scraped off by the rod-shaped body while the coating layer is in a fluid state, the concave portion can be easily formed without applying a load to the coating layer. As a result, the exothermic composition located in the recesses and the exothermic composition located between adjacent recesses, that is, the exothermic composition located in the projections, have the same composition, density, and the like, and the exothermic characteristics are less likely to be impaired. Further, since the recess can be formed with a simple device that simply inserts and pulls out the rod-like body from the coating layer, the device can be easily cleaned and maintained. The replacement of the rod-shaped body does not take time and cost.

  As shown in FIG. 1 (a), when the rod-like body 2 is inserted into the coating layer 3 formed on the substrate sheet 1 and the coating layer 3 is scraped off, FIG. As shown in FIG. 3, the scraped exothermic composition 4 may adhere to the rod-like body 2 without being removed. When scraping of the coating layer 3 proceeds in this state, the exothermic composition 4 attached to the rod-like body 2 may grow and become a lump 4a as shown in FIG. 1 (c). When the mass 4 a of the exothermic composition 4 reaches a certain size, the mass 4 a cannot continue to adhere to the rod-shaped body 2 and is separated from the rod-shaped body 2. The lump 4a itself of the separated exothermic composition 4 is not a foreign substance because it has the same composition as the exothermic composition constituting the coating layer 3. Therefore, even if the lump 4 a separated from the rod-like body 2 remains on the coating layer 3, the lump 4 a does not adversely affect the coating layer 3. Then, when the lump 4a is separated from the rod-like body 2, the rod-like body 2 returns to a state where the exothermic composition is not adhered or the amount of adhesion is small. That is, the rod-like body 2 is self-cleaned. As described above, the use of the rod-shaped body 2 is advantageous in that it is not necessary to frequently clean the rod-shaped body 2 because the cycle of adhesion of the exothermic composition 4, growth of the lump 4a, and separation and removal of the lump 4a occurs repeatedly. The effect is played. 1A to 1C show a state in which the base sheet 1 is traveling in a direction orthogonal to the paper surface.

  When forming a recessed part by scraping off the coating layer using a rod-shaped body, if one rod-shaped body is used, one recessed part will be formed. On the other hand, as shown in FIGS. 2A and 2B, a plurality of rod-like bodies 2 are used, and these are predetermined over a direction intersecting the traveling direction D of the base sheet 1 including the coating layer 3. When the base sheet 1 including the coating layer 3 is run under this condition, multiple recesses 5 extending in the running direction D are formed.

  When a plurality of rod-like bodies 2 are used as shown in FIGS. 2A and 2B, the lengths of the rod-like bodies 2 may be the same or different. When the length of each rod-shaped body 2 is set to be the same, the depth of each recess formed is the same. On the other hand, when the length of the rod-like body 2 is different, a recess having a depth corresponding to the length is formed.

  While the base sheet including the coating layer is traveling in one direction, the rod-shaped body is reciprocated in the direction intersecting the traveling direction while maintaining the state where the lower end of the rod-shaped body is in contact with the coating layer. By doing so, a concave portion having a mountain shape or a curved waveform can be formed. For example, when a rod-shaped body is reciprocated at a constant speed in a direction orthogonal to the base sheet including a coating layer while traveling in a direction at a constant speed, a concave portion meandering in a sine wave shape can be formed. .

  In addition, while the base sheet including the coating layer is traveling in one direction, the rod-shaped body is orthogonal to the surface of the coating layer while maintaining the state where the lower end of the rod-shaped body is in contact with the coating layer. When the reciprocating motion is performed in the direction in which the concave portion is formed, the depth of the concave portion changes in the direction in which the concave portion extends in the concave portion thus formed.

  Furthermore, while the base sheet including the coating layer is traveling in one direction, the rod-shaped body is moved in a direction intersecting the traveling direction while maintaining the state where the lower end of the rod-shaped body is in contact with the coating layer. While reciprocating, you may reciprocate a rod-shaped body in the direction orthogonal to the surface of a coating layer.

  The rod-shaped body is generally linear, and the rod-shaped body can be brought into contact with the coating layer at the lower end of the rod-shaped body in such a positional relationship that the extending direction is orthogonal to the surface of the coating layer. Instead, as shown in FIG. 3, when the traveling state of the base sheet 1 including the coating layer 3 is viewed from the side along the traveling direction D, the lower end 2a of the rod-like body 2 has its upper end. The rod-shaped body 2 is positioned downstream of the traveling direction D with respect to 2b, so that the rod-shaped body 2 is inclined with respect to the thickness direction W of the coating layer. The lower end 2 a may be brought into contact with the coating layer 3. By doing in this way, the resistance at the time of scraping off the coating layer 3 can be reduced, and the recessed part 5 can be formed, without applying a load further to a coating layer. Moreover, the self-cleaning property mentioned above can also be improved.

  As the rod-shaped body 2, for example, as shown in FIG. The lower end surface of the rod-like body 2 is a flat surface. It can replace with the rod-shaped body of this shape, and can also use the rod-shaped body shown in FIG.4 (b). The lower end of the rod-like body has a curved surface shape that is rounded downward. By using the rod-shaped body having this shape, it is possible to reduce the scraping resistance of the coating layer as compared with the case of using the rod-shaped body shown in FIG. From the viewpoint of further reducing the scraping resistance of the coating layer, a rod-like body shown in FIG. 4C can also be used. The lower end of this rod-like body has a tapered pointed shape. Therefore, when this rod-shaped body is used, the scraping resistance of the coating layer can be further reduced, and a narrow recess can be easily formed.

  The cross-sectional shape of the rod-shaped body is preferably an isotropic shape such as a circle or a regular polygon, for example, from the viewpoint of reducing the resistance of scraping of the coating layer. However, it is also possible to use an anisotropic transverse cross-sectional shape, for example, a rod-like body having an oval or rhombic cross section. When the cross section has an anisotropic shape, the aspect ratio (major axis / minor axis) is 50 or less, particularly 30 or less so that the resistance to scraping of the coating layer is not excessively hardened. From the viewpoint of Moreover, when a cross section is an anisotropic shape, it is preferable to arrange | position a rod-shaped body so that the major axis direction may correspond with the running direction of a base material sheet.

  When the cross-section of the rod-shaped body is circular, for example, the thickness of the rod-shaped body is 0.5 to 5 mm, particularly 1 to 3 mm in terms of diameter, so that a recess having a desired width can be reliably formed. To preferred. When the cross section is an isotropic shape, for example, when it is a regular polygon, it is preferable that the diameter of a circle circumscribing the regular polygon is in the above-described range. When the cross-section of the rod-shaped body is an anisotropic shape, for example, when it is an ellipse or a rhombus, the width of the rod-shaped body in the direction orthogonal to the running direction of the base sheet is preferably in the above range. .

  When a concave portion is formed in the coating layer, it is preferable to reduce the fluidity of the coating layer by reducing the moisture content of the coating layer in order to maintain the shape of the concave portion. For this purpose, it is preferable to use a substrate sheet having water absorption. In order to control the water absorption of the base sheet, for example, the type of fiber constituting the base sheet and the ratio of hydrophilic fiber / hydrophobic fiber, means such as adding a superabsorbent polymer to the base sheet, etc. Can be adopted. By appropriately combining these means, a sufficient fluid state can be maintained immediately after coating of the paint, and the fluidity of the coating layer can be reduced after a predetermined time.

  As another method, the lower end of the rod-shaped body may be brought into contact with the coating layer while being heated to a predetermined temperature, and the coating layer may be scraped off. By using a heated rod-like body, the moisture content of the coating layer at the site where the exothermic composition has been scraped off can be rapidly reduced, and the shape retention of the formed recesses can be easily and reliably increased. be able to. From this viewpoint, it is preferable to heat the rod-shaped body to 80 to 300 ° C, particularly 120 to 200 ° C. The rod-shaped body may be heated by, for example, connecting the upper end of the rod-shaped body thermally to a heat source and heating the lower end of the rod-shaped body to a predetermined temperature by heat transfer from the heat source.

  The above process relates to a method for forming a concave portion extending in a line in one direction in the surface layer portion of the coating layer. In this manufacturing method, after forming the concave portion, the second direction intersecting with the direction is the second. A second concave portion extending in the direction of may be formed to further increase the flexibility of the target heating element. From the viewpoint of making this flexibility more remarkable, it is preferable to set the crossing angle between the two directions to 45 degrees or more. In particular, the two directions are preferably orthogonal to each other from the viewpoint of developing substantially the same flexibility in any direction within the plane of the heating element. When the concave portions are formed in two different directions, the convex portions are not continuous but extend intermittently. In order to form recesses extending in two different directions, for example, while the base sheet including the coating layer is running, the lower end of the rod-shaped body is kept in contact with the coating layer while intersecting the running direction. The rod-shaped body is reciprocated in the direction of travel to form a corrugated recess extending in the running direction of the base sheet, and then another corrugated recess intersecting the corrugated recess is reciprocated in the same manner. May be formed.

  When the concave and convex portions are formed in two different directions, it is preferable to adjust the penetration depth of the rod-shaped body into the coating layer so that the lower end of the rod-shaped body is in contact with the surface of the base sheet. . By doing so, concave portions having the same depth as the thickness of the coating layer can be formed, and the circumference of each convex portion is surrounded by the exposed surface of the base sheet, and is individually partitioned. It becomes a state. By forming such a convex part, the flexibility of the target heating element can be further enhanced.

(3) Electrolyte addition process If a recessed part and a convex part are formed in the surface layer part of a coating layer in this way, electrolyte will be added to this coating surface side in a solid state or the state of aqueous solution. From the viewpoint of maintaining the shape of the concave and convex portions formed in the coating layer, it is advantageous to add the electrolyte in a solid state, which is an addition mode that does not increase the fluidity of the coating layer. 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 and to suppress the scattering of the electrolyte to the device and / or its surroundings as compared with the case where it is added as an aqueous solution. The

  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, dripping or spraying with a nozzle, application with a brush, die coating, etc. are used. 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 an electrolyte to the coating layer, a heat generating layer is formed, and a desired heat generating element is obtained. In the heat generating layer, a concave portion extending in a line shape in at least one direction is formed in the surface layer portion. When the heating element is in a form in which a heating layer is provided between two identical or different base material sheets, on the surface where the recess is formed in the heating layer in which the recess is formed in the surface layer part. A step of superimposing different base material sheets may be performed.

  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 consisting of a continuous long object was cut across its width direction, but instead, between the recess formation step and the electrolyte addition step, The base material sheet which consists of a continuous long thing in which the coating layer was formed may be cut | judged, and electrolyte may be added to this base material sheet used as each leaf by an electrolyte addition process.

  In the above manufacturing method, after forming a coating layer by applying a paint to the base sheet, a concave portion is formed in the coating layer, and an electrolyte is further added to form a heat generation layer. Instead of this, first, an electrolyte may be added to the base sheet in a solid state or in an aqueous solution, and then a paint may be applied, and then a recess may be formed to form a heat generating layer. Alternatively, instead of adding the paint and the electrolyte separately, the paint containing the oxidizable metal particles, the carbon component, water and the electrolyte is prepared, and the coating is applied to the base sheet, and then the recess is formed. Thus, a heat generating layer may be obtained.

  FIG. 5 shows an example of an apparatus preferably used in the manufacturing method. The apparatus includes a coating coating unit 10, a recess forming unit 20, an electrolyte adding 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. Furthermore, a suction box 13 is also provided opposite to the die lip of the die coater 11 with the endless belt 12 interposed therebetween. The base material sheet 1 made of a continuous long material fed from the raw material roll 1A of the base material sheet is conveyed by an endless belt 12, and a coating is applied to one surface of the base material sheet 1 by a die coater 11. It is formed. When the base sheet 1 is transported by the endless belt 12, the suction box 13 is operated to stabilize the transport, and the paint is sucked to stably hold the base sheet 1.

  The recess forming part 20 has a rod-like body 2. The rod-shaped body 2 is attached to the fixed plate 21 at the upper end position. The fixing plate 21 may have a mechanism capable of reciprocating in a direction orthogonal to the traveling direction of the base sheet 1 (a direction orthogonal to the paper surface in FIG. 5). Instead of this or in addition to this, the fixing plate 21 may have a mechanism capable of reciprocating in a direction (vertical direction in FIG. 5) perpendicular to the surface of the coating layer.

  The rod-shaped body 2 enters the coating layer at a predetermined angle with respect to the surface of the coating layer. Although the surface of the coating layer and the rod-shaped body 2 are generally orthogonal, other than that, for example, the angle relationship shown in FIG. One or a plurality of rod-like bodies 2 are used, and the upper ends thereof are attached to the fixed plate 21.

  The electrolyte addition unit 30 includes a nozzle 31 that drops an electrolyte aqueous solution. Moreover, the wire mesh endless belt 12 which opposes the opening part of the nozzle 31 and circulates in the arrow direction is also provided. Furthermore, a suction box 33 is also provided opposite the opening of the nozzle 31 with the endless belt 12 interposed therebetween. The base material sheet 1 after the coating is applied is conveyed by the endless belt 12 from the recess forming part 20 to the electrolyte adding part 30, and toward the coating layer of the base material sheet 1. The electrolyte is added in a solid state or in an aqueous solution state to form a heat generating layer. When transporting the base material sheet 1 in the electrolyte adding unit 30, the suction box 33 can be operated to stabilize the transport. By adding the electrolyte after coating the paint, it is possible to ensure the concentration of the electrolyte suitable for heat generation in the heat generating layer, and the electrolyte is concentrated by the moisture contained in the coating layer and the base sheet 1. As it is diluted, it is absorbed and held in the base sheet 1, and the moisture content and electrolyte concentration of the heat generating layer become suitable. Further, the suction of the suction box 33 during the addition of the electrolyte makes it easier for the electrolyte to penetrate into the base sheet 1.

  For the base sheet 1 in which the heat generation layer having a recess in the surface layer portion is formed, the base sheet 1 'made of a continuous long material is supplied on the surface of the heat generation layer where the recess is formed. The base sheet 1 'is overlaid on the heat generating layer. As a result, a continuous long body of heating elements provided with a heating layer is formed between two identical or different base material sheets 1, 1 ′.

  The structure of the heating element at this point is as shown in FIG. 6, and the heating layer as the coating layer 3 is disposed between two identical or different base material sheets 1 and 1 ′. A plurality of recesses 5 are formed in the heat generating layer so as to extend in one direction. Between the adjacent recessed parts 5, it is a convex part. The recess 5 is open toward the base material sheet 1 ′ side.

  The formed continuous long object of the heating element 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 passing between the two members, whereby a heating element 100A for each leaf is obtained.

  The continuous long object of the heating element may be cut so as to extend in the width direction of the continuous long object, for example, linearly across the width direction of the continuous long object. 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.

  In the re-pitch portion 50, the heating element 100A that has become a leaf is changed in pitch in the front and rear in the conveyance direction, and the heating elements 100A 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 100A is transported to the covering section 60, and is entirely covered by the first covering sheet 6 made of a continuous long object and the second covering sheet 7 also made of a continuous long object. When one base sheet is used and a heat generating layer is formed on one surface of the base sheet, the first covering sheet 6 covers the side of the heat generating body 100A where the heat generating layer is formed, The covering sheet 7 covers the side of the heating element 100A where the heat generating layer is not formed. When two base sheets are used and a heat generating layer is formed on one surface of the base sheet 1 and then another base sheet 1 ′ is overlaid on the heat generating layer, the first covering sheet 6 is The base sheet 1 ′ in the heating element 100A is covered, and the second covering sheet 7 covers the base sheet 1 in the heating element 100A. The heating element 100A 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 extended parts of the first and second cover sheets 6 and 7 extending from the front, rear, left and right of the heating element 100A are joined by heat sealing. This joining is a continuous airtight joining surrounding the heating element 100A, or a discontinuous joining surrounding the heating element 100A.

  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 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 thing in the 1st cutting part 40 is a curve, it is preferable to make the cutting line in this cutting part 80 into the curve which followed it.

  As shown in FIG. 7, the heating tool 100 obtained in this manner is entirely surrounded by a heating material 100 </ b> A with a packaging material 8 composed of a first covering sheet 6 and a second covering sheet 7. 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, which is one surface of the heating element 100A, is formed. The 1st covering sheet 6 is arrange | positioned, and the 2nd covering sheet 7 is arrange | positioned at the side of the surface in which the heat generating layer which is the other surface is not formed. When two base sheets are used and a heat generating layer is formed on one surface of the base sheet 1 and then another base sheet 1 ′ is superposed on the heat generating layer, the heating tool 100 is made of a heating element. A first covering sheet 6 is disposed on the base sheet 1 ′ forming one surface of 100A, and a second covering sheet 7 is disposed on the base sheet 1 forming the other surface. Yes.

A part of the first covering sheet 6 in the packaging material 8 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 using such a porous sheet, various fiber sheets such as needle punched nonwoven fabric and air-through nonwoven fabric are laminated on the outer surface of the porous sheet (the surface facing outward in the first covering sheet). Thus, the texture of the first cover sheet may be enhanced.

As the second covering sheet 7 in the packaging material 8, an appropriate one is selected according to the structure of the heating element. The second cover sheet 7 is preferably a sheet having a lower air permeability than the first cover sheet 6 from the viewpoint of stably generating water vapor through the first cover sheet 6. In particular, when the heat generating layer is not located on the second covering sheet 7 side, the second covering sheet 7 is preferably a sheet having a lower air permeability than the first covering sheet 6. 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 6 and has no breathability. Includes both cases. When the second cover sheet 7 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 7). 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 7 is a breathable sheet, the same breathable sheet as the first cover sheet 6 can be used. In this case, the air permeability of the second covering sheet 7 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 covering sheet 6 is lower than that of the first covering sheet 6. It is preferably 100,000 seconds / (100 ml · 6.42 cm ² ). When the second cover sheet 7 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 6 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 6 is disposed. In order to enable the generation of water vapor, (B) a method of adjusting the proportion of each component constituting the heat generating layer, assuming that the heat generating layer contains a large amount of water, (C) Examples thereof include a method of adjusting the air permeability of the first and second cover sheets 6 and 7 surrounding the heating element 100A, and 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 6 and the second covering sheet 7 have air permeability, the air permeability value of the first covering sheet 6 is smaller than the air permeability value of the second covering sheet 7. Therefore, the amount of water vapor released through the first cover sheet 6 is set to be larger than the amount of water vapor released through the second cover sheet 7. Is preferred. As long as the amount of water vapor released through the first cover sheet 6 is larger than the amount of water vapor released through the second cover sheet 7, water vapor is released through the second cover sheet 7. 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.

DESCRIPTION OF SYMBOLS 1 Base material sheet 2 Rod-shaped body 3 Coating layer 4 Exothermic composition 4a Lump of exothermic composition 5 Recessed part 6 First covering sheet 7 Second covering sheet 8 Packaging material 100 Heating tool 100A Heating element

Claims (8)

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 substrate sheet having water absorption,
While the substrate sheet is traveling in one direction, a coating layer is formed on one surface of the substrate sheet by applying a coating containing at least the oxidizable metal particles, and then the coating layer is in a fluid state The lower end of the rod-shaped body is brought into contact with the coating layer to scrape off part of the coating layer to form a streak-like recess extending in the same direction as the running direction of the base sheet. A method of manufacturing a heating element.   The manufacturing method of Claim 1 which forms the said recessed part of several strips using the said some rod-shaped body arrange | positioned over the direction which cross | intersects the running direction of the said base material sheet.   The manufacturing method according to claim 1 or 2, wherein a lower end of the rod-like body is sharp or rounded.   When the traveling state of the base sheet is viewed from the side along the traveling direction, the lower end of the rod-shaped body is located downstream of the upper end in the traveling direction, thereby the rod-shaped body. The manufacturing method as described in any one of Claim 1 thru | or 3 which is in the state inclined with respect to the thickness direction of the said coating layer.   The manufacturing method as described in any one of Claim 1 thru | or 4 which makes the lower end contact | abut to the said coating layer in the state which heated the said rod-shaped object.   One surface of the base sheet is coated with a coating that does not contain the electrolyte and the particles of the oxidizable metal to form the coating layer, and after forming the recesses in the coating layer, The manufacturing method according to any one of claims 1 to 5, wherein the exothermic composition layer is formed by adding the electrolyte to the coating layer in a solid state or in an aqueous solution state.   One surface of the base sheet is added with an aqueous solution that does not contain particles of the oxidizable metal and contains the electrolyte, or the electrolyte is added in a solid state, and then does not contain the electrolyte and is oxidizable. The manufacturing method according to any one of claims 1 to 5, wherein after applying a coating material containing metal particles, the concave portion is formed to form the layer of the exothermic composition.   The manufacturing method according to any one of claims 1 to 7, wherein after forming the concave portion in the coating layer, a substrate sheet that is the same as or different from the substrate sheet is stacked on the coating layer.

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