JP5620161B2 - Manufacturing method of heating element - Google Patents

Description

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

  A heating element technology is known in which a heat generating composition containing an oxidizable metal is laminated with a sheet having water absorption. For example, in a heating element in which an ink-like or cream-like exothermic composition is laminated and enclosed in a sheet-like packaging material, a part of the packaging material having air permeability and water absorption is used, and A heating element has been proposed in which a part of the moisture of the creamy exothermic composition is absorbed by the packaging material (see Patent Document 1). In this exothermic composition, excess water, free water and / or a hydrogel exhibits a function as a barrier layer against air, and the exothermic reaction is suppressed by the barrier layer. The barrier layer disappears when excess water or the like is absorbed by the packaging material having water absorption, and heat generation proceeds accordingly.

  In addition, the applicant previously applied a coating liquid containing an oxidizable metal powder, a fiber material, water and a water retention agent and having a water content of 40 to 75% by weight on a support. After forming a water-containing molded body and dehydrating the water-containing molded body to a predetermined moisture content, the dehydrated water-containing molded body is heated and dried to a predetermined moisture content to obtain an intermediate molded body. A method for producing a heat generating molded body was proposed in which a predetermined amount of an aqueous electrolyte solution was applied to the molded body to form a heat generating molded body (Patent Document 2).

JP-A-9-75388 JP 2004-143232 A

However, in the technique described in Patent Document 1, a heat-generating composition that is in a water-containing state and has viscosity is directly laminated with a sheet having air permeability, or a sheet having air permeability is coated in a state having viscosity. Therefore, the air permeability of the sheet is easily impaired by the viscosity of the exothermic composition, and as a result, a uniform exothermic reaction hardly occurs. In addition, the sheet on which the exothermic composition layer is formed is a packaging material, and the user's action is directly transmitted to the exothermic composition layer, whereby the exothermic composition layer is likely to fall off.
Further, in the technique described in Patent Document 1, when the exothermic composition is formed by stirring and kneading, there is an effect of suppressing heat generation by excess water, but since salt (electrolyte) and iron powder are stirred and kneaded at the same time, kneading The paint attached to the machine paddles, tank walls, etc. causes a violent oxidation reaction by losing moisture, so manufacturing equipment must use expensive materials with high corrosion resistance, such as titanium, and requires high capital investment. become.
Moreover, in the manufacturing method of the heat generating body described in Patent Document 1, since salt (electrolyte) and iron powder are stirred and kneaded at the same time, the resulting heat generating composition is liable to cause sedimentation and water separation of the components. It was difficult to maintain the dispersibility of these components.

  On the other hand, according to the method for producing the exothermic molded body described in Patent Document 2, since the electrolyte is not contained in the coating liquid, the intermediate molded body is formed by dehydrating and drying the coating liquid. When obtained, the oxidation of the oxidizable metal powder is difficult to proceed, and the components in the coating can maintain good dispersibility.

  However, since the manufacturing method of the exothermic molded object of patent document 2 has the process to spin-dry | dehydrate and the process to heat-dry, it exists in the tendency for a manufacturing process to become large. On the other hand, when this dehydration step and heat drying step are omitted, the surface of the heating element becomes easy to stick with the moisture in the coating liquid and the aqueous electrolyte solution, increasing the burden of maintenance on the production equipment, When covered with a breathable packaging material, the packaging material may be blocked, making it difficult to obtain desired heat generation performance.

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.

  As a result of diligent investigations to solve the above problems, the present inventors have used a fiber sheet containing a superabsorbent polymer as a base sheet, and an oxidizable metal particle and an aqueous electrolyte solution to be contained in a layer of a heat generating composition. In a separate process, the dispersibility of the components in the coating is maintained by adding the tip of the oxidizable metal particles and the electrolyte aqueous solution later, and also suppresses the oxidation of the oxidizable metal in the manufacturing process. It has been found that a heating element having good heat generation characteristics can be produced, and that the moisture content of the heating layer of the heating element can be easily controlled.

  The present invention has been made on the basis of the above-described knowledge, and the base material is composed of a fiber sheet in which a layer of a heat generating composition containing particles of an oxidizable metal, an electrolyte and water comprises particles of a superabsorbent polymer and a fiber material. A method of manufacturing a heating element provided on a sheet, wherein a coating step of applying a coating containing particles of the oxidizable metal not including the electrolyte on one surface of the base sheet, and the coating The manufacturing method of the heat generating body provided with the electrolyte addition process which adds the electrolyte aqueous solution containing the said electrolyte to the said base material sheet | seat coated is provided.

According to the method for producing a heating element of the present invention, it is possible to produce a heating element having good exothermic characteristics by maintaining good dispersibility of the components in the paint and suppressing oxidation of the oxidizable metal powder in the production process. At the same time, it is easy to control the moisture content of the heating layer of the heating element.
According to the method for producing a heating tool of the present invention, even when a breathable sheet is used as a packaging material for a heating element, the breathability is not hindered, or the layer of the heating composition is difficult to fall off, and the heat generation excellent in heat generation characteristics. Tools can be manufactured.

FIG. 1 is a schematic diagram illustrating a longitudinal cross-sectional structure of a base sheet used in Example 1. FIG. FIG. 2 is a schematic view showing an example of an apparatus preferably used for manufacturing the heating element or heating tool of the present invention. FIG. 3 is a schematic view showing another example of an apparatus preferably used for manufacturing a heating element or a heating tool of the present invention.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
The heating tool manufactured by the manufacturing method of the heating tool of the present invention includes a heating element and a packaging material as its constituent members. The heating element manufactured by the method for manufacturing a heating element of the present invention is preferably used as a heating element of the heating tool, for example. A heating element as a constituent member of a heating tool is a member that generates heat in the heating tool. On the other hand, the packaging material of the heating tool is a member that surrounds the entire heating element and forms the outer surface of the heating tool of the present invention.

First, the heating element manufactured by the manufacturing method of the heating element of the present invention will be described.
A heating element manufactured by the method for manufacturing a heating element of the present invention includes a base sheet and a layer of a heat generating composition (hereinafter also referred to as “heating layer”) provided on one surface of the base sheet. The base sheet is composed of a fiber sheet containing superabsorbent polymer particles and a fiber material. The heat generating layer includes particles of an oxidizable metal.

  The base sheet made of a fiber sheet may be (a) one sheet in a state where the particles of the superabsorbent polymer and the fiber material are uniformly mixed. In the base sheet, (b) the 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. It can also be one-ply with a structure that is not. Further, the base sheet may be (c) a laminate of two fiber sheets in which particles of a superabsorbent polymer are arranged between the same or different fiber sheets containing a fiber material. Of these base sheets that can take various forms, it is preferable to use the base sheet having the form (b) from the viewpoint of easily controlling the moisture content of the heat generating layer.

As the fiber material contained in the base sheet made of a fiber sheet, both hydrophilic fibers and hydrophobic fibers can be used, but it is preferable to use hydrophilic fibers. As the hydrophilic fiber, any of natural fiber and synthetic fiber can be used.
By using hydrophilic fibers as the constituent fibers of the base 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. . In addition, the use of hydrophilic fibers also has the advantage that the water absorption or water retention of the base 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.

  As chemical fibers of cellulose, for example, rayon and acetate can be used. On the other hand, as natural cellulose fiber, various plant fibers, wood pulp, non-wood pulp, cotton, hemp, wheat straw, hemp, jute, kapok, palm, rush, etc. can be used. Of these cellulose fibers, it is preferable to use wood pulp from the viewpoint that a thick fiber can be easily obtained. The use of thick fibers as the cellulose fibers is free from the viewpoints of water absorption or water retention of the base sheet, retention of the heat generating layer, and the like.

  In particular, it is preferable to use bulky cellulose fibers as the natural cellulose fibers. By using the bulky cellulose fiber, it becomes easy to make the inter-fiber distance of the constituent fibers in the base sheet suitable. As specific examples of the bulky cellulose fiber, (a) the fiber shape has a three-dimensional structure of a twisted structure, a crimped structure, a bent and / or branched structure, or (b) the fiber roughness is 0.2 mg / m or more. Or (c) those in which the intramolecular and intermolecular molecules of the cellulose fiber are crosslinked.

  Specific examples of the fiber having a three-dimensional structure such as a twisted structure, a crimped structure, a bent structure and / or a branched structure of (a) above include chemical pulp obtained by decomposing wood pulp by a chemical reaction, and mechanical treatment ( Pulp decomposed by beating) or pulp obtained by combining chemical reaction and mechanical treatment can be used.

  In the fiber (b), cellulose fibers are accumulated in a bulky state, whereby the movement resistance of the liquid is reduced, and the liquid permeation rate is high. When such a fiber is used, when the paint is applied to the base sheet in the process of manufacturing the heating element described later, moisture in the paint easily moves into the base sheet. It becomes easy to control the water content. In addition, a bulky network structure that can hold the solid content constituting the heat generating layer is easily formed. From these viewpoints, the fiber roughness of the fiber (b) is preferably 0.2 to 2 mg / m, particularly preferably 0.3 to 1 mg / m.

  The fiber roughness is used as a scale representing the fiber thickness in fibers having non-uniform fiber thickness, such as wood pulp. For example, a fiber roughness meter (FS-200, KAJANNIELECTRONICSLTD. ). Examples of cellulose fibers having a fiber roughness of 0.2 mg / m or more include softwood kraft pulp (“ALBACEL” (trade name) manufactured by Federal Paper Board Co. and “INDORAYON” (trade name) manufactured by PT Inti Indorayon Utama. )] And the like.

The fiber (b) preferably has a roundness of the fiber cross section of 0.5 to 1, particularly 0.55 to 1. By using the cellulose fiber having such roundness, the movement resistance of the liquid in the base sheet is further reduced, and the passing speed of the liquid is further increased. The method for measuring roundness is as follows. The fiber is sliced perpendicular to the cross-sectional direction so that the area does not change, and a cross-sectional photograph is taken with an electron microscope. The cross-sectional photograph is analyzed by an image diffractometer [“Avio EXCEL” (trade name) manufactured by Nippon Avionics Co., Ltd.], and the cross-sectional area and circumference of the measurement fiber are measured. Using these values, the roundness is calculated using the following formula. The roundness is an average value obtained by measuring 100 arbitrary fiber cross sections.
Roundness = 4π (cross-sectional area of measurement fiber) / (peripheral length of cross-section of measurement fiber) ²

  When wood pulp is used as the bulky cellulose fiber, the cross section of the wood pulp is generally flattened by delignification treatment, and most of the roundness is less than 0.5. In order to make it 0.5 or more, for example, the wood pulp may be mercerized to swell the cross section of the wood pulp. Examples of commercially available mercerized pulp include “FILTRANIER” (trade name) manufactured by ITT Rayonier Inc. and “POROSANIER” (trade name) manufactured by the same company.

  The crosslinked cellulose fiber as the fiber (c) is preferable because it can maintain a bulky structure even in a wet state. Examples of the method for crosslinking the cellulose fiber include a crosslinking method using a crosslinking agent. Examples of such crosslinking agents include N-methylol compounds such as dimethylolethyleneurea and dimethyloldihydroxyethyleneurea; polycarboxylic acids such as citric acid, tricarballylic acid and butanetetracarboxylic acid; polyols such as dimethylhydroxyethyleneurea A cross-linking agent for polyglycidyl ether compounds. The amount of the crosslinking agent used is preferably 0.2 to 20 parts by weight with respect to 100 parts by weight of the cellulose fiber. The crosslinked cellulose fiber has a fiber roughness of preferably 0.1 to 2 mg / m, particularly preferably 0.2 to 1 mg / m. The cross-linked cellulose fiber preferably has a roundness of the fiber cross section of 0.5 to 1, particularly 0.55 to 1. Examples of commercially available crosslinked cellulose fibers include “High Bulk Additive” manufactured by Weyerhaeuser Paper Co.

  Among the fibers (a) to (c) described above, particularly when the fiber (c) is used, the integrity of the base sheet and the heat generating layer is enhanced, and the advantageous effect that the heat generating layer is less likely to fall off. Is played. Further, the heating element becomes flexible, and there is an advantageous effect that the fitting property is improved when the heating tool of the present invention is attached to an object to be attached, for example, the skin or clothing of a human body. Surprisingly, it is worth noting that the flexibility of the heating element is maintained even after the end of heat generation.

  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 substrate sheet by a wet method or a dry method.

  In addition to the above-described hydrophilic fibers, heat-fusible fibers may be blended in the base sheet as necessary. By blending this fiber, the strength of the substrate 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 base sheet.

  As described above, the base sheet made of the fiber sheet contains particles of the 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. For the joining, for example, the viscosity generated by wetting the particles of the superabsorbent polymer can be used. Further, a superabsorbent polymer particle formed by attaching and polymerizing a liquid material containing a polymerizable monomer and / or a polymerized product of the monomer to a web made of a fiber material may be used. The particles of the superabsorbent polymer are bonded to the fiber material.

  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 may be provided only on one side of the base sheet, or may be provided on both sides. The heat generating layer is a water-containing layer containing particles of an oxidizable metal, an electrolyte, and water. The heat generating layer may further contain a reaction accelerator. The heat generating layer may be present on the base sheet, or the lower part thereof may be buried in the base sheet. That is, a part of solid content constituting the heat generating layer may be carried in a three-dimensional network formed on the fiber sheet constituting the base 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 reaction accelerator, it is preferable to use a reaction accelerator that has a function as an oxygen retention / supply agent for an oxidizable metal in addition to acting as a moisture retention agent. Examples of the reaction accelerator include activated carbon (coconut shell charcoal, charcoal powder, calendar bituminous coal, peat, lignite), carbon black, acetylene black, graphite, zeolite, perlite, vermiculite, silica 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.

The amount of oxidizable metal in the heating element, 100~3,000g / m ² expressed as basis weight, to be particularly 200~1,500g / m ^2, from the viewpoint of securing a sufficient heating value. The amount of the reaction accelerator in the heating element is preferably 4 to 80 g / m ² , particularly 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 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 heat generating layer loses its fluidity and eventually loses its viscosity. As a result, as described later, even if a sheet having air permeability is arranged on the upper side of the heat generating layer, the inconvenience that the air permeability of the sheet is impaired by sticking of the heat generating layer is less likely to occur. 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 portion located above the surface of the base sheet is taken out in a nitrogen environment, and its weight is measured. Then, it puts into a drying oven with a temperature of 105 ° C. in a vacuum state for 2 hours to remove moisture, measures the weight again, and measures the water content.
The moisture content of the heat generating layer is a value per heat generating layer.

By setting the moisture content of the heat generating layer within the above range, the heat generating layer is effectively prevented from sticking to the breathable sheet disposed thereon. There may be a concern that the heat generation characteristics are reduced due to the decrease in the amount of the above. However, in the present invention, since the base sheet contains water and water is supplied from the base sheet to the heat generating layer during heat generation, the heat generation characteristics are not deteriorated. In particular, since the base sheet contains a superabsorbent polymer, and the release of water from the superabsorbent polymer proceeds gradually, the heat generation characteristics are stable over a long period of time. From these viewpoints, the proportion of water in the heating element, that is, the moisture content of the heating element is preferably 10 to 60% by mass, particularly 12 to 50% by mass. The specific method for measuring the moisture content of the heating element is as follows. In other words, the weight of the heating element was measured under a nitrogen environment, and then placed in a vacuum oven at a temperature of 105 ° C. for 2 hours to remove moisture, and the weight was measured again. The difference weight was included as the moisture content. Calculate the amount of water.
The moisture content of the above-mentioned heating element is a value when one heating layer is formed on the base sheet, but satisfies the above range even when a heating layer is formed on each surface of the base sheet. Is preferred.

  In the heating element, it is preferable from the viewpoint of achieving uniform heat generation that water is uniformly present throughout the entire surface (the entire area in the plane direction and the entire area in the thickness direction). The rate part and the low water content part may be mixed. For example, stripe-shaped high water content portions and low water content portions extending in one direction can be alternately formed in the in-plane direction of the heating element. By adopting such a configuration, the rigidity of the heating element can be made different between the high moisture content part and the low moisture content part, and thereby the heating tool is attached to an object to be attached, for example, human skin or clothing. There is an advantageous effect that the fit at the time becomes even better. From this viewpoint, it is preferable that the moisture content in the high moisture content site | part in the heating tool of this invention is 20-60 mass%, especially 25-50 mass%. On the other hand, the moisture content at the low moisture content region is preferably 10 to 40% by mass, particularly preferably 10 to 30% by mass.

As a method of forming a high water content portion and a low water content portion in the surface direction of the heating element, in the coating process described later, a paint is applied over a wide range in the surface direction of the base sheet, and the subsequent electrolyte In the adding step, a method of patterning the aqueous electrolyte solution in the region of the base sheet coated with the paint is preferable. Examples of the pattern distribution pattern include a stripe pattern (striped pattern), a lattice pattern, a checkered pattern, and a dot pattern.
As a planar view shape of each dot of the dot pattern, a circle, a rhombus, an ellipse, a quadrangle, a triangle and the like can be given. In order to form a high water content part and a low water content part by spraying a pattern of an aqueous electrolyte solution, in addition to the formation of parts with different rigidity, the heat generation temperature varies depending on the part of the heating element, for example, heat is required. An advantageous effect is that a single heating element can contribute both temperatures to a sensitive body part, where a body part and a mild temperature are preferred. The reason why the parts with different rigidity are formed is that the part where the electrolyte is sprayed becomes hard as the heating element undergoes the oxidation reaction, whereas the part where the electrolyte is not sprayed contains water. This is because the rate is low, the oxidation reaction stops in the middle, and the portion remains soft as compared with the portion where heat generation continues.

Further, as a method of forming the high moisture content portion and the low moisture content portion in the surface direction of the heating element, in the coating process described later, the basis weight and moisture content of the paint are different from each other in the surface direction of the base sheet. In the subsequent electrolyte addition step, an aqueous electrolyte solution may be dispersed in the region of the base sheet where the paint is applied.
Moreover, you may combine patterning of coating of a coating material and patterning of electrolyte addition.

  In the heating element, when the heating layer is formed only on one surface of the base sheet, the moisture content on the side of the base sheet where the heating layer is not provided is the moisture content of the heating layer. Is preferably lower. In this way, moisture is supplied to the heat generation layer for heat generation on the side where the heat generation layer is formed, while the substrate sheet and the covering sheet are provided on the side where the heat generation layer is not provided. Adhesiveness is prevented, and an advantageous effect is obtained that the air flow in the heating tool is hardly hindered. In order to achieve such a moisture content relationship, it is advantageous to use, for example, a substrate sheet having the above-described structure (b) or (c). In the base sheet having the structure of (b) or (c), since the superabsorbent polymer particles are unevenly distributed in the central region in the thickness direction, a heat generating layer is formed only on one surface of the base sheet. This is because water permeation is prevented at the site where the superabsorbent polymer particles are unevenly distributed, so that the water content on the opposite side of the base sheet can be kept low.

  In the heating tool manufactured by the heating tool manufacturing method of the present invention, the heating element described above is surrounded by the packaging material. This packaging material preferably includes a first cover sheet and a second cover sheet. The first cover sheet is disposed on the heat generating layer side of the heat generating element. The second cover sheet is disposed on the side of the heat generating element where the heat generating layer is not formed, or is disposed on the side of the heat generating layer (for example, when the heat generating layer is formed on both sides).

  It is preferable that the first cover sheet and the second cover sheet each have an extension region extending outward from the peripheral edge of the heating element, and the extension regions are joined to each other. This joining is preferably an annular continuous airtight joining. The packaging material formed by joining both covering sheets has a space for accommodating a heating element therein. A heating element is accommodated in this space. In the case where the joints between the extension regions are annular and continuous airtight joints, it is ensured that solids (for example, oxidizable metal particles) are removed from the heating element contained in the packaging material. Since it is prevented, it is preferable.

It is preferable that the heating element accommodated in the packaging material is not fixed to the packaging material. That is, it is preferable that the heating element is not restrained by the packaging material and can be moved independently of the packaging material. In this case, for example, when a pressure-sensitive adhesive is applied to the second covering sheet in the packaging material to form a pressure-sensitive adhesive portion, and the heating tool of the present invention is attached to the user's skin or the like via the pressure-sensitive adhesive portion, Even if the second cover sheet is pulled due to the operation, the pulled state does not propagate to the heating element, so that the solid content (for example, oxidizable metal particles) from the heating element Dropout is effectively prevented.
Further, since the heating element is not constrained, it can move independently from the packaging material, and since it is difficult to adhere to the covering sheet, the air permeability of the covering sheet is not hindered. Moreover, the flow of air around the base sheet is not inhibited in the packaging material, and a good exothermic reaction can be obtained.

A part of the first covering sheet in the packaging material has air permeability, or the whole has air permeability. As described above, since the first covering sheet is disposed to face the heat generating layer in the heat generating portion, the first covering sheet has air permeability, so that the supply of oxygen to the heat generating layer is smooth. Performed, and stable heat generation is maintained for a long time. From this point of view, the air permeability of the first covering 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 ), In particular, it is preferably 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 in the packaging material, an appropriate one is selected according to the structure of the heating element. The second cover sheet is preferably a sheet having a lower air permeability than the first cover sheet from the viewpoint of stably generating water vapor through the first cover sheet. In particular, when the heat generation layer of the base sheet is not located on the second covering sheet side, the second covering sheet is preferably a sheet having lower air permeability than the first covering sheet. The “sheet with low air permeability” as used herein refers to a non-breathable sheet that is partially breathable but has a lower degree of breathability than the first covering sheet and does not have breathability. Includes both cases. When the second cover sheet is a non-breathable sheet, examples of the non-breathable sheet include a synthetic resin film, a needle punched non-woven fabric on the outer surface of the film (the surface facing outward in the second cover sheet), A composite sheet obtained by laminating various fiber sheets including a nonwoven fabric such as an air-through nonwoven fabric can be used. When the second cover sheet is a breathable sheet, the same breathable sheet as the first cover sheet can be used. In this case, the air permeability of the second cover sheet is 200 to 150,000 seconds / (100 ml · 6.42 cm ² ), particularly 300 to 100, provided that the air permeability of the second cover sheet is lower than that of the first cover sheet. It is preferably 000 seconds / (100 ml · 6.42 cm ² ). When the second cover sheet 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 is in close contact with the user's skin or clothes, for example.

In the heating element, the heating layer may be formed on only one side of one base sheet, or may be formed on both sides. In the case of forming on both surfaces, for example, a base material sheet to which a coating material described later is applied can be formed through a second coating material coating process by inverting the upper and lower surfaces with a turn bar or the like.
Moreover, the heating element accommodated in the heating tool may be one or may be accommodated in a multilayer state in which a plurality of heating elements are laminated.

The heating tool manufactured by the manufacturing method of the present invention can generate water vapor from the side where the first cover sheet is disposed. In order to enable the generation of water vapor, (b) on the premise that the heat generating layer contains a large amount of water, (b) a method of adjusting the proportion of each component constituting the heat generating layer, (c) Examples thereof include a method of adjusting the air permeability of the first and second covering sheets surrounding the heating element, and a method of using (d) (b) and (c) in combination. In the heating tool of the present invention, a large amount of water can be retained when the base sheet contains hydrophilic fibers. Due to this, the heating tool of the present invention can generate a large amount of water vapor. Moreover, in the heating tool, since the base sheet contains a hydrophilic polymer in addition to containing the hydrophilic fiber, the base sheet can hold a large amount of water also by this, As a result, a large amount of water vapor can be generated. The ratio of each component constituting the heat generation layer (b) is as described above. The air permeability of the first and second covering sheets in (c) is also as described above. The amount of water vapor that is released through the first cover sheet ^{4, 0.01~0.8mg / (cm 2 · min} ) in accordance with the measuring method described later, especially 0.03~0.4mg / (cm ² · min) It is preferable that

  When both the first cover sheet and the second cover sheet have air permeability, the air permeability value of the first cover sheet is made smaller than the air permeability value of the second cover sheet (that is, It is preferable that the amount of water vapor released through the first cover sheet is greater than the amount of water vapor released through the second cover sheet by increasing air permeability. As long as the amount of water vapor released through the first cover sheet is greater than the amount of water vapor released through the second cover sheet, it is impeded that water vapor is released through the second cover sheet. I can't.

The amount of water vapor released through the first cover sheet is measured as follows. That is, heating is started by bringing the heating tool into contact with air at 20 ° C. and 65% RH. Immediately place the heating tool on a pan balance capable of measuring 1 mg, and then measure the mass for 15 minutes. Steam generated from the following equation when the mass at the start of measurement is Wt ₀ (g), the mass after 15 minutes is Wt ₁₅ (g), and the steam generation area of the heating tool is S (cm ² ) Calculate the amount of
Water vapor release [mg / (cm ² · min)] = {(Wt ₀ −Wt ₁₅ ) × 1000} / 15S

  The first covering sheet in the packaging material may have an adhesive layer formed by applying an adhesive on the outer surface thereof. The pressure-sensitive adhesive layer is used for attaching the heating tool of the present invention to human skin or clothing. As an adhesive which comprises an adhesion layer, the thing similar to what was used until now in the said technical field including a hot-melt adhesive can be used. From the point of not impairing the air permeability, it is preferable to provide an adhesive layer at the edge of the first cover sheet.

Next, preferred embodiments of the above-described heating element and heating tool manufacturing method, that is, the heating element manufacturing method and heating tool manufacturing method of the present invention will be described.
A preferred embodiment of the method for producing a heating element of the present invention includes (1) a coating step and (2) an electrolyte addition step which will be described below. In a preferred embodiment of the method for manufacturing a heating tool of this embodiment, a heating element covering and sealing step (heating) in which (3) the manufactured heating element is surrounded by a packaging material after the heating element manufacturing process is used. A surrounding step in the manufacturing method of the tool.

(1) Coating process In the coating process which is one process of the manufacturing process of a heat generating body, the base material sheet is coated with a coating material not containing an electrolyte and containing particles of an oxidizable metal. The electrolyte here means an electrolyte added for the purpose of dissolving the oxide formed in the oxidizable metal particles, and does not mean that it does not contain all the electrolytes. 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.
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 to cause the aggregate to settle or separate.
According to the method for manufacturing a heating element of the present invention, as described above, since the electrolyte is not actively contained in the paint, it was created while the paint was being created in the manufacturing equipment such as a tank. While applying the paint, it is difficult for the oxidation reaction to occur 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 with high corrosion resistance in the manufacturing equipment.

  The paint usually contains a reaction accelerator and water in addition to the oxidizable metal particles. 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 continuously applied on one surface of a base sheet made of a continuous long material, for example. Moreover, as a coating method of a coating material, various well-known coating methods can be especially used without a restriction | limiting. For example, roll coating, die coating, screen printing, roll gravure, knife coating, curtain coater and the like are used. Die coating is preferable from the viewpoint of easy application, easy control of the application amount, and uniform coating of the paint.

In the paint used for forming the heat generating layer, the reaction accelerator is preferably contained in an amount of 1 to 20 parts, particularly 2 to 14 parts with respect to 100 parts of the oxidizable metal particles. It is preferable that water is contained in 25 to 85 parts, particularly 35 to 75 parts. The thickener is preferably contained in an amount of 0.05 to 10 parts, particularly 0.1 to 5 parts. The surfactant is preferably contained in an amount of 0.1 to 15 parts, particularly 0.2 to 10 parts.
Further, water is preferably contained in an amount of 18 to 48 mass%, particularly 23 to 43 mass%, assuming that the total mass of the paint is 100%.
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.

  By applying the coating material, a continuous coating layer is formed on one surface of the base sheet. In this case, since the base sheet contains particles of the superabsorbent polymer, water contained in the paint is appropriately absorbed and held in the superabsorbent polymer, and the water content of the paint layer is determined by the water content of the paint. Decrease than rate. As a result, the fluidity of the paint layer decreases. Moreover, since the base material sheet contains the fiber material, the water contained in the paint is appropriately absorbed and held in the base material sheet, and the water content of the paint layer is reduced. The paint layer is a portion that becomes the heat generating layer by adding an aqueous electrolyte solution later to the coated surface, and the water content of the paint layer is higher than the surface of the base sheet, similarly to the water content of the heat generating layer. It is measured for the part that is located. Therefore, the part embedded in the base material sheet in the paint layer is excluded from the measurement target of the moisture content. The water content of the paint layer is the same as the method for measuring the water content of the heat generating layer.

The coating is performed so that the moisture content of the entire sheet including the base sheet and the coating layer is 50 to 95%, particularly 60 to 90%, of the moisture content of the finally obtained heating element. It is preferable from the viewpoint of applying a coating material to a base material and a heating element including an electrolyte aqueous solution to be added later to produce desired heat generation. The moisture content of the entire sheet including the base sheet and the paint layer was measured by measuring the weight of the entire sheet in a nitrogen environment, and then placed in a vacuum oven at 105 ° C. for 2 hours to remove moisture. Again, the weight is measured, and the water content is calculated using the difference weight as the water content.
The coating basis weight of the paint is preferably 150 to 4,600 g / m ² , particularly preferably 300 to 2,200 g / m ² .

The coating is applied while sucking from the side of the base sheet opposite to the side where the coating is applied (the other side, hereinafter also referred to as the non-coating side). This is preferable from the viewpoint of incorporating the solid content in the paint containing metal particles between the fiber materials of the base sheet. By incorporating particles of oxidizable metal into the base material sheet, the integrity of the paint layer or heat generating layer and the base material sheet is increased, and the heat generating layer is removed from the base material sheet (before, during, and before use). After) is effectively prevented.
The suction from the non-application surface side of the base sheet may be performed after the application of the paint and before the addition of the aqueous electrolyte solution, instead of being performed simultaneously with the application of the paint.
The suction force is preferably 100 to 10,000 Pa, particularly 500 to 5,000 Pa. The suction force can be measured by attaching a manostar cage to the box in the suction conveyor.

(2) Electrolyte addition process In the electrolyte addition process which is one process of the manufacturing process of a heat generating body, electrolyte aqueous solution is added to the one surface side which coated the coating material of the base material sheet after coating a coating material. The method of adding the electrolyte aqueous solution includes dripping or spraying with a nozzle, application with a brush, die coating, etc., but the production facility by preventing the electrolyte aqueous solution from scattering to the surroundings, blocking the electrolyte aqueous solution discharge port, and contacting with the paint From the viewpoint of preventing contamination, it is preferable to drop or spray using a nozzle.

By applying the paint, the paint layer formed on one surface of the substrate sheet contains the aqueous electrolyte solution and becomes the heat generation layer described above. In this case, the moisture in the previously applied paint is absorbed and retained by the superabsorbent polymer because the base sheet contains particles of the superabsorbent polymer, and the water content of the paint layer is determined by the water content of the paint. It is lower than the rate. Therefore, even if an aqueous electrolyte solution is added in this step, the fluidity of the heat generation layer formed thereby is not so high. Therefore, even if the obtained heat generating body is laminated | stacked on a breathable sheet, it becomes a thing which does not inhibit the breathability easily.
In particular, as described above, when the suction from the non-coated surface side of the base sheet is performed during coating and / or before the addition of the electrolyte aqueous solution after coating, the concentration and amount of the electrolyte aqueous solution, etc. The degree of freedom increases.

  However, if the strong suction from the non-coated surface side of the base sheet is performed even during the addition of the electrolyte aqueous solution, the moisture content necessary for heat generation may not be maintained in the heat generation layer. Does not perform suction from the non-coated surface (other surface side) of the base sheet, or is weaker than the suction during or after the coating of the paint and before the addition of the aqueous electrolyte solution It is preferable to perform suction under conditions. However, if necessary, the suction during the addition of the aqueous electrolyte solution can be performed under a condition stronger than the suction during the application of the paint or after the application of the paint and before the addition of the aqueous electrolyte solution. .

Also, considering that the concentration of the electrolyte added to the base sheet is reduced by the moisture in the paint remaining in the base sheet, the electrolyte aqueous solution added in the electrolyte addition step is the ratio of the electrolyte in the aqueous solution (normal concentration) However, it is preferable to use an electrolyte that is higher than the ratio of the electrolyte and the total amount of water in the heating element from the viewpoint of obtaining good heating performance in the finally obtained heating element.
In the aqueous electrolyte solution to be added, the electrolyte is preferably contained in an amount of 3 to 35% by mass, particularly 5 to 30% by mass.
The coating (spreading) basis weight of the aqueous electrolyte solution is preferably 30 to 400 g / m ² , particularly 50 to 300 g / m ² .
The addition amount of electrolyte (in terms of solid content) is 0.5 to 15 parts, particularly 1 to 10 parts, with respect to 100 parts addition amount per same area of the oxidizable metal particles in the coating step described above. It is preferable.

(3) Heating element covering sealing process (enclosing process)
When a heating element made of a continuous long object is manufactured by the above operation, the heating element is covered with a packaging material in a heating element covering and sealing process subsequent to the heating element manufacturing process. Prior to this operation, it is preferable to produce a heating element for each leaf by cutting a heating element made of a continuous long object in the width direction. Next, while running the heating element of each leaf in one direction at a predetermined interval, the first covering sheet made of a continuous long object is disposed on the side where the heating layer is formed, and on the other side, Similarly, a second covering sheet made of a continuous long object is disposed. 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 the arrangement of the first cover sheet on the heat generating layer, the water content of the heat generating layer is reduced and the fluidity is reduced, so even if the first cover sheet is disposed on the heat generating layer, The disadvantage that the heat generating layer sticks to the first cover sheet is avoided. As a result, the air permeability of the first cover sheet is successfully maintained.

  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 the above-described 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 addition, (3) the heating element made of a continuous long product is cut in the width direction prior to the heating element covering and sealing step, but (2) the heat generation made of a continuous long product prior to the electrolyte addition step. You may perform electrolyte addition of (2) electrolyte addition process to the base material sheet | seat after cutting a body and apply | coating the coating material which became every leaf.

The heating tool of the present invention produced in this way 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, 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.
Moreover, the heat generating body manufactured by this invention can also be used for the heat generating tool of another structure other than the heat generating part of the heat generating tool of this invention, and another use. When used for heating the human body, the first covering sheet that generates water vapor is applied toward the skin side (human body side).

  FIG. 2 shows an example of an apparatus preferably used for manufacturing the heating element or heating tool of the present invention. The apparatus includes a paint coating unit 20, an electrolyte addition 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 20 includes a die coater 21. Moreover, the endless belt 22 of the wire mesh which opposes the die lip of the die coater 21 and circulates in the arrow direction is also provided. Furthermore, a suction box 23 is also provided opposite to the die lip of the die coater 21 with the endless belt 23 interposed therebetween. 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 22, and a paint is applied to one surface thereof by a die coater 21. A paint layer is formed. When the base sheet 1 is transported by the endless belt 22, the suction box 23 is operated to stabilize the transport, and water in the paint is sucked to adjust the amount of water absorbed and retained by the base sheet 1. be able to. Since the water in the paint is absorbed by the base material sheet 1 by applying the paint, the water content of the paint layer is lower than the water content in the paint. As a result, the fluidity of the paint layer decreases.

  The electrolyte addition unit 30 includes a nozzle 31 that drops an electrolyte aqueous solution. Further, an endless belt 22 made of a wire mesh that faces the opening of the dropping nozzle 31 and circulates in the direction of the arrow is also provided. Furthermore, a suction box 33 is also provided opposite to the opening of the dropping nozzle 31 with the endless belt 22 interposed therebetween. The substrate sheet after coating is conveyed from the coating unit 20 to the electrolyte adding unit 30 by the endless belt 22, and the aqueous electrolyte solution is dropped from the nozzle hole of the dropping nozzle 31 toward the coating surface of the substrate sheet. A heating layer is formed. 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 aqueous electrolyte solution after coating, the concentration of the electrolyte suitable for heat generation can be secured in the heat generating layer, and the concentration of the aqueous electrolyte solution is diluted by the moisture contained in the paint layer and the base sheet 1. However, the moisture content and the electrolyte concentration of the heat generation layer (paint layer) are suitably absorbed and retained by the base sheet 1. Moreover, the penetration of the aqueous electrolyte solution is improved to the inside of the base sheet by suction of the suction box when the aqueous electrolyte solution is sprayed.

  When the heating element 10A made of a continuous long object is formed in this way, the heating element 10A is cut in the first cutting part 40 in the width direction. The first cutting unit 40 includes a rotary die cutter 42 having a cutter blade 41 on the peripheral surface and an anvil roll 43. Cutting is performed by the heating element 10A passing between both members, whereby the heating element 10 of each leaf is obtained.

  The heating element 10A made of a continuous long object may be cut so as to extend in the width direction of the heating element 10A. For example, the heating element 10A can be linearly formed in the width direction of the heating element 10A. 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.

  In the re-pitch portion 50, the heating element 10 that has become a leaf is changed in pitch in the front-rear direction in the transport direction, and the heating elements 10 that are adjacent to each other in the front-rear direction 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 10 is conveyed 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. The first cover sheet 4 covers the side of the heat generating element 10 where the heat generating layer is formed, and the second cover sheet 5 covers the side of the heat generating element 10 where the heat generating layer is not formed. While maintaining this covering state, the heating element 10 is introduced into the sealing portion 70 by the endless belt 61 provided in the covering portion 60. The sealing portion 70 includes a first roll 71 having a seal convex portion 72 on the peripheral surface and a second roll 73 having the seal convex portion 72 on the peripheral surface. Both rolls 71 and 73 are arranged in a positional relationship such that the axial directions thereof are parallel and the seal bars 72 and 72 of the rolls 71 and 73 are in contact with each other or a predetermined clearance is generated between them. Has been. In the sealing part 70, the extended part of the 1st and 2nd coating sheets 4 and 5 extended from the front and rear, right and left of the heat generating body 10 is joined by heat sealing. This joint is a continuous airtight joint surrounding the heating element 10 or a discontinuous joint surrounding the heating element 10.

  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 and an anvil roll 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 heating element 10A in the first cutting part 40 described above is, for example, a straight line, the cutting line in the main cutting part 80 is also preferably a straight line. In addition, when the cutting line of the heating element 10A in the first cutting part 40 is a curve, the cutting line in the main cutting part 80 is preferably a curved line.

  FIG. 3 shows another example of an apparatus preferably used for manufacturing the heating element or heating tool of the present invention. The apparatus shown in FIG. 3 has the same configuration as the apparatus shown in FIG. 2 except that the arrangement position of the re-pitch part 50 is different and the suction box is not arranged in the electrolyte addition part 30. That is, in the apparatus of FIG. 2, the first cutting part 40 is disposed between the electrolyte addition part 30 and the re-pitch part 50, whereas in the apparatus of FIG. 3, the coating part 20 and the electrolyte addition part 30 are arranged. The 1st cutting part 40 is arrange | positioned between. In the apparatus of FIG. 3, the electrolyte adding unit 30 is not provided with suction means such as a suction box that performs suction from the non-coated surface side of the base sheet. Other than these, the apparatus of FIG. 3 has the same configuration as the apparatus of FIG.

  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 by mass of oxidizable metal (iron powder average particle size 45 μm), 8 parts by mass of reaction accelerator (activated carbon average particle size 42 μm), thickener (gua gum) 0 .2 parts by mass, 0.2 part by mass of a surfactant (polycarboxylic acid type polymer surfactant) and 60 parts by mass of water were used. The viscosity of the obtained paint was 6,500 mPa · s. The viscosity was measured using a No. 4 rotor of a B-type viscometer in an environment of 23 degrees and 50% RH .
A sodium chloride aqueous solution having a concentration of 5% was prepared as an aqueous electrolyte solution.

(2) Preparation of substrate sheet The substrate sheet shown in FIG. 1 was used. This base material sheet 1 was produced according to the method described in JP-A-8-246395. In the base sheet 1, the sodium polyacrylate-based superabsorbent polymer particles 12 are mainly present in a substantially central region in the thickness direction of the base sheet 1, and the particles are formed on the surface of the base sheet 1. 12 (one ply) having a structure in which 12 does not substantially exist. The base material sheet 1 has layers 11 and 13 of hydrophilic cross-linked bulky cellulose fibers 11a on the front and back sides of the site where the superabsorbent polymer particles 12 are present. The crosslinked bulky cellulose fiber 11a had a fiber roughness of 0.22 mg / m and an average fiber length of 2.5 mm. The layers 11 and 13 of the crosslinked bulky cellulose fiber 11a further contain a softwood bleached kraft pulp and a paper strength enhancer (PVA). A superabsorbent polymer having an average particle size of 340 μm was used. The basis weight of the layer 11 was 30 g / m ² , and the basis weight of the layer 13 was 20 g / m ² . The basis weight of the superabsorbent polymer particles 12 was 30 g / m ² . Therefore, the basis weight of the base material sheet 1 was 80 g / m ² .

(3) Production of heating element and heating tool The coating material was continuously applied to one surface of the base sheet made of a continuous long article. The coating basis weight of the paint was 1,150 g / m ² . During coating, suction was performed from the other side of the base sheet. However, water in the paint did not escape from the non-coated surface side of the base sheet.
Next, after cutting the substrate sheet made of continuous long material across the width direction, the electrolyte aqueous solution is dropped from the dropping nozzle toward the surface (coated surface) of the cut substrate sheet coated Thus, the heating element 10 was obtained. When the aqueous electrolyte solution was added, suction from the non-coated surface side of the base material sheet was not performed. The spraying basis weight of the aqueous electrolyte solution was 80 g / m ² .
The cut base sheet was a 50 mm × 50 mm rectangle.

  The obtained heating element 10 was entirely covered with the first cover sheet 4 and the second cover sheet 5. At this time, the side where the heat generating layer is formed in the heating element 10 is covered with the first covering sheet 4, and the side where the heating layer is not formed in the heating element 10 is covered with the second covering sheet 5. . Next, the extending portions of the first and second cover sheets 4 and 5 extending from the front, rear, left and right of the heating element 10 were joined by heat sealing. This joining was a continuous airtight joining surrounding the heating element 10. The seal width was 5 mm.

As the first covering sheet 4, a polyethylene porous sheet having a basis weight of 50 g / m ² and an air permeability of 2500 s / (100 ml · 6.42 cm ² ) was used. As the second cover sheet 5, a non-ventilated sheet made of a polyethylene film having a basis weight of 30 g / m ² was used. Moreover, each coating sheet 4 and 5 was a 65 mm x 65 mm rectangular thing.

  As a result of measuring each water content by the above-mentioned method, the water content of the sheet 10A ′ having the paint layer after coating and before the addition of the aqueous electrolyte solution is 28% (including the paint layer). The moisture content of the heating element 10 before coating with the coating sheet 4 was 32%, and the moisture content of the heating layer of the heating element 10 was 8%.

Moreover, about the obtained heat generating body 10, temperature measurement was performed by the test method based on the thermal apparatus for JIS S4100 disposable warmer temperature characteristic measurement. The obtained heating tool 100 was inserted into a needle punched nonwoven fabric bag having a basis weight of 100 g / m ² and placed on a constant temperature bath at 40 ° C. to evaluate temperature characteristics. This bag is formed into a bag shape by sealing three sides of the needle punched nonwoven fabric. The thermometer is disposed between the heating tool 100 and the surface of the thermostatic chamber. The heating tool 100 was placed so that the side on which the heat generation layer was formed faced upward (the direction opposite to the thermometer). As a result, the maximum temperature reached 57 ° C. 10 minutes after the start of measurement.

DESCRIPTION OF SYMBOLS 1 Base sheet 10 Heat generating body 11 Layer of hydrophilic fiber 12 Particle of superabsorbent polymer 13 Layer of hydrophilic fiber 100 Heating tool

Claims (5)

A method for producing a heating element, wherein a layer of a heat generating composition containing particles of an oxidizable metal, an electrolyte and water is provided on a base sheet made of a fiber sheet containing particles of a superabsorbent polymer and a fiber material. ,
An application step of applying a paint containing particles of the oxidizable metal not containing the electrolyte on one surface of the base material sheet, and an electrolyte containing the electrolyte on the base material sheet coated with the paint The manufacturing method of a heat generating body provided with the electrolyte addition process which adds aqueous solution.   The method for manufacturing a heating element according to claim 1, wherein suction is performed from the other surface side of the base sheet during coating of the paint or after the coating of the paint and before the addition of the aqueous electrolyte solution. Wherein during the addition of the electrolyte solution, the production of heating elements according to claim 2, wherein performing suction at different conditions than the previous SL and before the addition of the electrolyte solution suction after coating the coating or in the coating of paint Method. The electrolyte aqueous solution, in the coating the coating material in the base sheet region, patterned spraying method for manufacturing a heating element according to any one of claims 1-3. Includes an enclosure step of enclosing the heating element manufacturing process for manufacturing a heating element by the manufacturing method of the heating element according to any one of claims 1-4, and a whole of the resulting heating element packaging material,
In the heating element manufacturing step, a heating element in which the layer of the heating composition does not have fluidity is manufactured, and in the surrounding step, the heating element in that state is surrounded by the packaging material to form a heating tool. Manufacturing method of the tool.

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