JP2006087923A - Method for producing exothermic shaped product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an exothermic shaped product which can adjust the moisture content of the exothermic shaped product rapidly and low and can produce the exothermic shaped product with good heat generating characteristics by using a simple manufacturing facility. <P>SOLUTION: A paper-making process which makes paper from a raw material composition comprising an oxygenated metal powder, a water retaining agent, a fibrous substance, an electrolyte, and water, and forms an intermediate shaped product, and a drying process which holds this intermediate shaped product formed at this paper-making process on its surface and back surface and heats and dries it while it is pressed. A pressing force in the drying process is 500 Pa-20 MPa, and the drying temperature is 60-300°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a heat-generating molded body using heat generated by an oxidation reaction between oxygen in air and an oxidizable metal powder.

  For example, a technique described in Patent Document 1 below is known as a related art relating to a method for producing a heat-generating molded body using heat generated by an oxidation reaction between oxygen in air and an oxidizable metal powder.

JP-A-1-201253

  This technology suspends a fibrous material in water, adds an oxidizable metal such as iron powder, activated carbon as a water retention agent, an electrolyte as a reaction aid to make a raw slurry, and makes paper from the raw slurry. After the suction dehydration, the exothermic molded body is manufactured by dehydrating and forming into a sheet having a predetermined moisture content by pressing.

  By the way, in the above-mentioned conventional technology, since an electrolyte as a reaction aid is added to the raw material slurry, oxidation of the oxidizable metal has already begun at the time of dehydration molding after papermaking, and in order to suppress this oxidation reaction, The manufacturing equipment has to be complicated, for example, the manufacturing process must be performed in an atmosphere of an inert gas such as nitrogen or argon. In addition, it is practically difficult to quickly reduce the moisture content to 50% or less only by press dehydration. A method for producing an exothermic molded body that can quickly adjust the moisture content of the exothermic molded article to a low level during molding to suppress the oxidation reaction. Was desired.

  Accordingly, an object of the present invention is to provide a method for manufacturing a heat-generating molded body that can adjust a moisture content quickly and easily with a simple manufacturing facility and can manufacture a heat-generating molded body having good heat generation characteristics. It is in.

  The present inventors made an intermediate molded body from a raw material composition containing an oxidizable metal powder, a water retention agent, a fibrous material, an electrolyte and water, and then heated the intermediate molded body with a high oxidizable metal. It has been found that by heating under predetermined drying conditions under heating that is considered to be reactive, the moisture content after molding can be kept low and an exothermic molded article having excellent exothermic characteristics can be produced.

  The present invention has been made on the basis of the above findings, and a papermaking process for forming an intermediate formed body by papermaking a raw material composition containing an oxidizable metal powder, a water retention agent, a fibrous material, an electrolyte and water, The present invention provides a method for producing an exothermic molded body comprising a drying step in which the intermediate molded body formed in the papermaking process is dried while being sandwiched and pressed on the front and back surfaces thereof.

  According to the present invention, the moisture content of the exothermic molded body can be quickly adjusted to low during molding with a simple manufacturing facility, and a exothermic molded body having good exothermic characteristics can be manufactured.

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

  In the present invention, first, an intermediate formed body is made from a raw material composition containing at least an oxidizable metal powder, a water retention agent, a fibrous material, an electrolyte, and water in a paper making process.

  As the oxidizable metal powder contained in the raw material composition, an oxidizable metal powder conventionally used in exothermic molded bodies can be used without particular limitation. Examples of the oxidizable metal powder include: , Iron powder, aluminum powder, zinc powder, manganese powder, magnesium powder, calcium powder, and the like. Among these, iron powder is preferably used from the viewpoints of handleability, safety, and manufacturing cost. The oxidizable metal powder has a particle size (hereinafter referred to as the maximum length in the form of the powder) of 0 because of its good fixability to a fibrous material and good control of the reaction. It is preferable to use one having a particle size of 1 to 300 μm, and more preferably one having a particle size of 0.1 to 150 μm containing 50% by weight or more.

  The blending amount of the oxidizable metal powder in the raw material composition excluding the electrolyte and water is preferably 10 to 90% by weight, and more preferably 30 to 80% by weight. If it is less than 10% by weight, the temperature increase of the resulting exothermic molded body may not be substantially obtained. If it exceeds 90% by weight, the powder may fall off or the resulting molded body may have air permeability. It may be damaged.

  As the water retention agent contained in the raw material composition, a water retention agent conventionally used in exothermic molded articles can be used without particular limitation. In addition to functioning as a water retention agent, the water retention agent also has a function as an oxygen retention / supply agent for the oxidizable metal powder. Examples of the water retention agent include activated carbon (coconut husk charcoal, charcoal powder, calendar bituminous coal, peat, lignite), carbon black, acetylene black, graphite, zeolite, perlite, vermiculite, silica, and the like. Activated carbon is preferably used from the viewpoint of performance, oxygen supply ability and catalytic ability. The water retention agent is preferably one having a particle size of 0.1 to 500 μm from the viewpoint that an effective contact state with the oxidizable metal powder can be formed. It is more preferable to use what is contained.

  The amount of the water retention agent in the raw material composition excluding the electrolyte and water is preferably 0.5 to 60% by weight, and more preferably 1 to 50% by weight. If the amount is less than 0.5% by weight, water necessary for sustaining the reaction may not be accumulated. If the amount exceeds 60% by weight, the heat capacity of the obtained heat-generating body with respect to the heat generation amount increases, and the heat generation temperature rises. May become smaller.

  As the fibrous material contained in the raw material composition, natural and synthetic fibrous materials can be used without any particular limitation. Examples of the fibrous material include plant fibers (cotton, kabok, wood pulp, non-wood pulp, peanut protein fiber, corn protein fiber, soy protein fiber, mannan fiber, rubber fiber, hemp, manila hemp , Sisal, New Zealand hemp, Rafu hemp, eggplant, rush, straw, etc.), animal fiber (wool, goat hair, mohair, cashmere, alkapa, Angola, camel, vicuña, silk, feathers, down, feather, algin fiber, chitin Fiber, casein fiber, etc.) and mineral fiber (asbestos, etc.). Examples of synthetic fibers include semi-synthetic fibers (acetate, triacetate, acetate acetate, promix, chlorinated rubber, hydrochloric acid rubber, etc.), synthetic fiber Molecular fiber (nylon, aramid, polyvinyl alcohol, polyvinyl chloride, polysalt) Vinylidene, polyesters such as polyethylene terephthalate, polyacrylonitrile, acrylic, polyethylene, polyethylene, polypropylene, polystyrene, polyurethane, rayon, viscose rayon, cupra and the like), metal fibers, carbon fibers, and glass fibers. These recovered and reused products can also be used. Among these, wood pulp, cotton, polyester from the viewpoints of fixability with the powder contained in the raw material composition, flexibility of the resulting exothermic molded body, oxygen permeability due to the presence of voids, production cost, etc. Is preferably used. The fibrous material preferably has an average fiber length of 0.1 to 50 mm, and more preferably 0.2 to 20 mm. If the fiber length is too short, the strength of the resulting exothermic molded article may not be sufficiently secured. If the fiber length is too long, the dispersibility in water will be reduced and a uniform thick exothermic molded article cannot be obtained. There is a case.

  The blending amount of the fibrous material in the raw material composition excluding the electrolyte and water is preferably 2 to 80% by weight, and more preferably 5 to 50% by weight. If it is less than 2% by weight, other components such as the oxidizable powder contained in the raw material composition cannot be retained and may fall off. If it exceeds 80% by weight, the heat generation of the resulting exothermic molded body The heat capacity with respect to the quantity increases, and the temperature rise may be reduced.

  As the electrolyte contained in the raw material composition, those conventionally used for exothermic molded bodies can be used without particular limitation. Examples of the electrolyte include alkali metal, alkaline earth metal, or heavy metal sulfate, carbonate, chloride, or hydroxide. Among these, various chlorides such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, and iron chloride (first and second) are preferably used from the viewpoint of excellent conductivity, chemical stability, and production cost.

  The blending amount of the electrolyte in the raw material composition is preferably 0.5 to 30%, more preferably 3 to 25% by weight to water. If it is less than 0.5%, the oxidation reaction of the exothermic molded body to be obtained may be suppressed, and if it exceeds 30%, excess electrolyte may be deposited and the air permeability of the resulting exothermic molded body may be impaired. is there.

  In the present invention, in addition to the oxidizable metal, the fibrous material, the water retention agent, and the electrolyte, the raw material composition includes a sizing agent, a colorant, a paper strength enhancer, a yield improver, a filler, Additives usually used in papermaking such as thickeners, pH control agents, bulking agents and the like can be added without particular limitation. The blending amount of the additive in the raw material composition can be appropriately set according to the additive to be added.

Next, the raw material composition is paper-made to form an intermediate molded body having a predetermined form.
As the paper making method of the intermediate formed body, a conventional paper making method used for paper making can be used without particular limitation depending on the form of the exothermic formed body to be formed such as a sheet shape or a three-dimensional shape. As the paper making method, for example, when the intermediate formed body is in a sheet form, a paper making method using a continuous paper making type circular net paper machine, long net paper machine, short net paper machine, twin wire paper machine, etc. In the case where the intermediate molded body has a three-dimensional shape, for example, Japanese Patent No. 3155522 (page 2, line 4, line 17 to page 4, line 8, line 23). ), For example, the so-called core paper making method described in Japanese Patent No. 3155503 (2nd page, 4th row, 4th line to 4th page, 7th row, 6th line), for example, Japanese Patent No. 3072088 (second page, 4th page). The so-called underwater laminating method) described in 4th row to 3rd page, 5th row, 43th row) and the like. In the papermaking process, the fibrous material can be further combined with the surface of the molded body.

  The intermediate molded body preferably has a moisture content (weight moisture content, the same shall apply hereinafter) of 70% or less, more preferably from the viewpoint of maintaining the form after paper making (shape retention) and maintaining mechanical strength. It is preferable to dehydrate until it becomes 60% or less. The dewatering method of the intermediate molded body can be appropriately selected according to the form of the intermediate molded body and the papermaking method. As the dehydration method, for example, when the intermediate molded body is a sheet-like molded body, in addition to dehydration by suction, a method of dehydrating by blowing pressurized air, dehydrating by pressing with a pressure roll or a pressure plate In addition, in the case where the intermediate molded body is a molded body obtained using a papermaking mold, a method of dehydrating by spraying pressurized air or the like on the intermediate molded body that has been made into a papermaking mold, Examples of the dehydration method include a method in which the intermediate formed body formed in the papermaking mold is pressed against the inner surface of the papermaking mold and dehydrated.

  Next, the intermediate molded body formed in the paper making process is heated and dried in the drying process while being sandwiched and pressed on the front and back surfaces. Thus, by heating and drying while pressing the intermediate molded body in a state of being sandwiched between the front and back surfaces, contact between oxygen in the air on the front and back surfaces and the oxidizable metal powder in the intermediate molded body is suppressed. At the same time, the contact between the oxidizable metal powder in the intermediate molded body and oxygen in the air is suppressed as much as possible by water vapor generated from the intermediate molded body with heat drying. For this reason, it is not necessary to use an inert gas atmosphere as in the prior art in the drying process, and the equipment can be greatly simplified. Further, since it is heated and dried under a pressed state, the moisture content of the molded body can be quickly reached to the moisture content of the target exothermic molded body, and also in this respect, the oxidizability during the production of the exothermic molded body. The oxidation of the metal powder can be extremely suppressed.

  The pressure when sandwiching and pressing the intermediate molded body in the drying step is preferably 500 Pa to 20 MPa in terms of moldability, and moreover 0.2 MPa in terms of moisture removability, shape transferability, and moldability. More preferably, it is 20 MPa, and further preferably 0.5 MPa to 8 MPa. If the pressing force is less than 500 Pa, isolation between oxygen in the air and the intermediate molded body may be insufficient, and the oxidation reaction may proceed. If the pressure exceeds 20 MPa, the structure of the intermediate molded body becomes dense. In some cases, the air permeability may be impaired, and the flexibility of the molded body may be impaired.

  The sandwiching method of the intermediate molded body can be appropriately selected according to the form of the intermediate molded body, the processing method of the intermediate molded body before drying, the moisture content before drying, the mechanical strength, and the like. Examples of the sandwiching method include a method using a press, a sandwiching method using a pressure roll or a press plate, a sandwiching method using a camber, and a method of contacting an elastic body under pressure.

  Moreover, it is preferable that the drying temperature in a drying process is 60-300 degreeC, It is more preferable that it is 80-250 degreeC, It is further more preferable that it is 100-200 degreeC. When the drying temperature is less than 60 ° C., there may be insufficient isolation between the oxidizable metal powder and oxygen in the air by water vapor generated from the intermediate molded body. It may be difficult to control the moisture content, or the structure of the molded body may be destroyed due to rapid vaporization of moisture.

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

  In the present invention, the moisture content of the intermediate molded body (exothermic molded body) after drying is preferably 10 to 60%, and more preferably 30 to 40%. If the water content is less than 10%, the oxidation reaction may not be promoted during use and the temperature may not be increased substantially. If the water content exceeds 60%, contact between the oxidizable powder and oxygen may occur. In some cases, sufficient temperature cannot be obtained, and a substantial increase in temperature cannot be obtained, or it takes time for the increase in temperature to occur.

  After the intermediate molded body is dried as described above, the moisture content can be adjusted and stabilized as necessary to obtain a heat generating molded body. Then, if necessary, it can be trimmed, laminated, etc., and processed into a predetermined size.

The exothermic molded body thus obtained has a thickness of 0.1 to 10 mm, a basis weight of 100 to 5000 g / cm ² , and an exothermic temperature of 30 to 150 ° C., for example, in a sheet form. This is an exothermic molded body.

The exothermic molded body thus obtained can be further coated with a coating layer having oxygen permeability. The coating layer may have oxygen permeability over the entire surface, or may partially have oxygen permeability. Any coating layer having oxygen permeability can be used without particular limitation. The coating layer can be provided by, for example, laminating paper, non-woven fabric, a multiporous film, a resin film having fine pores, etc., and impregnating a heat-resisting molded body with a synthetic resin paint or an emulsion paint. It can also be provided.
The obtained exothermic molded body is provided in a non-oxygen permeable, non-water permeable packaging bag or the like in order to avoid contact with oxygen before use.

  As described above, according to the heating element manufacturing method of this embodiment, the manufacturing process under an inert gas atmosphere or the like as in the prior art is unnecessary, and the moisture content of the heating element is reduced with simple manufacturing equipment. It is possible to adjust the temperature quickly during molding, and it is possible to produce an exothermic molded article having good exothermic characteristics.

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

  The present invention can be applied to exothermic molded bodies having a three-dimensional shape in addition to sheet-like exothermic molded bodies.

Exothermic molded bodies were produced as in Examples 1 to 3 and Comparative Example 1 below, and the exothermic molded bodies obtained were examined for exothermic characteristics (temperature of the exothermic molded body) as follows. The heat generation characteristics of these examples and comparative examples are shown in FIGS.
[Examples 1-3]
<Combination of raw material composition>
Oxidizable metal powder: iron powder (average particle size 45 μm), 15 g
Fibrous material: Pulp fiber (average fiber length 1.3 mm), 2.25 g
Water retention agent: activated carbon (average particle size 40 μm), 7.5 g
Electrolyte: NaCl, 25g
Water: Distilled water, 500ml
<Paper making conditions>
The slurry made of the above raw material was deposited on a # 50 mesh net using a Buchner funnel having a diameter of 170 mm.
<Dehydration conditions>
Subsequent to the paper making process, the Buchner funnel was used for suction dehydration for 1 minute to obtain an intermediate molded body having a water content of 70%.
<Drying conditions>
The obtained intermediate molded body was set to a pressing force and a drying temperature described in Table 1 with a press machine, and the drying time was adjusted so that the target moisture content was 40%, and the sheet was molded into a sheet shape.
<Form of intermediate molded body>
The obtained intermediate molded body had a thickness of 2.8 to 2.9 mm and a basis weight of 1850 to 1910 g / m ² .

[Comparative Example 1]
Using the same raw material composition as in Example 1, paper was made in the same manner as in Example 1, dehydrated and sucked, then dehydrated and dried while pressing with the press machine under the conditions shown in Table 1, but the water content was 40. %, The moisture content was further adjusted for 1 hour in an environment of 25 ° C. and a relative humidity of 50% so that the ultimate moisture content was about 40%.

[Measurement of heat generation characteristics]
About each exothermic molded object obtained in Examples 1-3 and the comparative example 1, it cut | judged to the dimension of 50 mm x 50 mm, and it was heat_generation | fever when it was made to heat | fever-generate on a polystyrene foam in the air of air temperature 25 degreeC and relative humidity 50%. Characteristics (temperature of the exothermic molded body) were examined.

  As shown in FIG. 1, it was confirmed that the exothermic molded bodies obtained in Examples 1 to 3 showed stable exothermic characteristics and the exothermic temperature reached a sufficient temperature. On the other hand, as shown in FIG. 2, the exothermic molded body obtained in Comparative Example 1 had a considerably lower exothermic temperature than that of the Examples.

It is a figure which shows the heat_generation | fever characteristic of the heat_generation | fever molded object obtained by the Example of this invention. It is a figure which shows the heat_generation | fever characteristic of the heat_generation | fever molded object obtained by the comparative example.

Claims (3)

A papermaking process for forming an intermediate molded body by papermaking a raw material composition containing an oxidizable metal powder, a water retention agent, a fibrous material, an electrolyte and water, and the intermediate molded body formed in the papermaking process on the front and back surfaces A heat-generating molded body comprising a drying step of heating and drying while sandwiching and pressing in
The manufacturing method of the exothermic molded object whose pressing force in the said drying process is 500 Pa-20 Mpa, and whose drying temperature is 60-300 degreeC.   The method for producing an exothermic molded body according to claim 1, further comprising a step of dehydrating the intermediate molded body formed in the paper making process to a moisture content of 70% or less before drying by heating.   The method for producing an exothermic molded body according to claim 1 or 2, wherein the drying step is performed in air.