JPS5851489A - Heating mat - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a heating mat that can use inexpensive iron powder such as powder.

In general, heating elements such as disposable body warmers utilize the heat generated when iron is oxidized in the air.
A breathable inner bag is filled with an aqueous electrolyte solution, which is then sealed in a non-breathable outer bag.

Oxidation of iron starts from the surface, and iron rust (1-
A layer of FeOOH, a-FeOOH, 7s304, etc.) is formed. When this rust layer is formed, the oxidation reaction slows down, and fewer spacings occur. Therefore, when the entire surface of the iron powder is covered with the iron rust layer, the amount of heat generated decreases, and the amount of heat required as a heating element decreases. Without being replaced, the iron powder loses its function as a heating element before the inside of the iron powder is oxidized.

Therefore, in order to ensure a longer duration, reduced iron, which has a large surface area and resembles a sponge in shape, is now generally used as iron powder.

However, reduced iron is manufactured using a special method and is therefore expensive. Therefore, reduced iron powder accounts for a major part of the cost of heating elements such as disposable body warmers.

Moreover, since the surface area is only expanded, the reaction mechanism is the same as that of the conventional one, and the problem of a decrease in calorific value due to the formation of an iron rust layer remains unsolved.

The inventor of the present invention can use iron powder in which no iron rust layer is formed on the surface of the iron powder, and therefore the surface area is not very large.
As a result of intensive research to develop a heating mat capable of reacting to the inside of iron powder, we were able to achieve the objective of achieving value by using iron powder coated with a conductive porous layer. The present invention has been completed.

That is, the present invention relates to a heating mat formed by enclosing a mixture of iron powder coated with a conductive porous layer, an electrolyte aqueous solution, and a carbonaceous material in a bag.

The exothermic reaction in the heating mat of the present invention is considered to occur in two stages as follows.

The first stage is a reaction similar to that in an air leakage battery that occurs on the surface of iron powder. That is, the iron powder constitutes a negative electrode, the carbonaceous material constitutes a positive electrode, the electrolyte aqueous solution corresponds to an electrolytic solution, and the conductive porous layer corresponds to a conductive wire. In this reaction, iron dissolves from the surface of the iron powder, becomes Fe, reacts with OH'' in the aqueous solution, produces 1.(OH)g, and 2e remains in the iron powder.
passes through an electrically conductive porous layer to the carbonaceous material, and the carbonaceous sludge donates oxygen from the air to the aqueous solution to maintain the OH concentration in the aqueous solution. As a result, no iron rust occurs on the surface of the iron powder, and theoretically all of the iron can be subjected to the reaction.

In the second stage, lFe(OH)2 generated in the first stage is oxidized by oxygen in the air on the surface of the aqueous solution, and
This is a reaction that produces 3.

Both the first and second stage reactions are exothermic reactions, and can provide a sufficient amount of heat required for the heating mat.

As mentioned in the explanation of the first step, in the present invention, iron rust does not form on the surface of the iron powder, so there is no need to use iron powder with a large surface area, and it cannot be used in heating bodies such as conventional disposable body warmers. Cheap iron powder such as scrap iron can be used, and its usage can be reduced.

The iron powder coated with a conductive porous layer used in the present invention can be obtained by uniformly mixing conductive carbonaceous material powder and iron powder with a porous material, solidifying the mixture, and then forming the iron powder into an appropriate size. It can be destroyed by crushing it.

Examples of conductive carbonaceous materials include carbon black, charcoal powder, carbon fiber, graphite powder, etc. Carbon black is extremely fine particles of 10 to 5 Qnm or less, so it can be mixed uniformly, and even a small amount increases conductivity. This is preferable because it is also inexpensive.

As the porous forming material, for example, cement, Ceracola, natural rubber latex, synthetic rubber latex, polymer cement mixed with various synthetic resin emulsions, polymer cement, etc. are preferable, and cement with good affinity for iron is particularly preferable. A foaming agent such as aluminum powder may be added to the cement. When aluminum powder is used, hydrogen gas generated during foaming can prevent air oxidation of iron powder during production. In addition, commonly known cement admixtures, such as setting retardants, hardening accelerators, dispersants, coagulants, thickeners, AIc agents, elasticity imparting agents, swelling agents, sealing agents, etc., may be added as appropriate. You may.

The blending ratio (overlapping) of carbonaceous material and porous material is 1:60
The range of 4:60 is preferable. Since the amount of electron transfer can be adjusted by adjusting the blending ratio of the carbonaceous material, the amount of heat generated can be controlled by adjusting the blending ratio of the carbonaceous material.

The conductive porous forming material is preferably the ones mentioned above, but is not limited to them, and any material that can easily conduct water and electricity can be used. If the amount of the porous forming material used is too small, the coating will be complicated and the formed porous layer may peel off, and if the amount used is too large, problems will occur with the movement of electrons, both of which are undesirable. For the section (overlapping section, the same shall apply hereinafter),
For example, in the case of cement, about 15 to 100 parts is appropriate.

As the iron powder to be coated, scrap iron can be used as described above, but other iron powders such as iron powder obtained by an atomization method, reduced iron, carbonyl iron powder, etc. may also be used.

However, from the point of view of price, scrap iron and powder are preferable.

The particle size of the iron powder is preferably as fine as possible, but it may be about 62 mesh pass. It is also possible to use small pieces of thin iron plate (for example, tin or galvanized iron) in the form of chips.

Besides iron powder coated with a conductive porous layer,
Carbonaceous materials and aqueous electrolyte solutions are used in the present invention.

1! Examples of the aqueous solution that can be used include sodium chloride, calcium chloride, potassium chloride, ammonium chloride, sodium hydroxide, potassium hydroxide, and calcium hydroxide. The substance acts to take in oxygen from the air, and examples thereof include activated carbon and charcoal powder, with activated carbon being particularly preferred.

In addition to these components, a heat storage material for storing generated heat may be added. The heat storage material is preferably a solid material with a large heat capacity, such as (1 grain of sand, silica gel, acrylamide, etc.), and grains of sand are particularly preferred from the viewpoint of large heat capacity and price.

In general, the void percentage oxidation of iron is not very severe, so the rise in temperature at the start of heat generation is slow, and if left as it is, it takes more than an hour to reach 40°O. Therefore, at the beginning of use, the disposable warmer must be vigorously stirred by shaking or kneading, and even in that case, it takes more than 40 minutes to reach 40°0.6oThere are various methods to solve this problem of temperature rise. Some also contain an initial exothermic agent. In the present invention, such an initial exothermic agent may also be blended.

The present inventor has also conducted extensive research on initial exothermic agents, and has focused on the fact that the reaction in the second stage, that is, the reaction in which re(oH)g is oxidized to y・203, proceeds extremely slowly. It has been found that Pa(OH)2 is generated at the beginning of use and is immediately oxidized to 1°203, thereby allowing a rapid temperature rise.

To generate Fll(OH)2 in the exothermic agent, a ferrous salt such as FeSO4.7)120 or Fe012 and a metal hydroxide such as Oa(OH)2 or NaOH are mixed in a bag. They may be mixed when enclosing them. These children may be selected as appropriate depending on the desired rise speed.

When such an initial exothermic agent is applied to the present invention, a mixture of iron powder and iron salt and a mixture of metal hydroxide and other components may be separately sealed, and then the two may be mixed after being sealed. . However, if such an initial exothermic agent is not used, all the components may be mixed in advance and sealed in the bag.

The preferred blending ratio of the heating mat of the present invention is ``
Iron powder in iron powder coated with conductive porous layer 1
00 parts, carbonaceous material 0.6 to 15s and electrolyte aqueous solution 12.6 to 70v6 (0.6 to 10 parts of electrolyte material dissolved in 12 to 60 parts of water), and heat storage agent is 0.
~70m.

The contents that can be incorporated into the heating mat of the present invention have been described above, but these contents are filled into a breathable inner bag, and then polyethylene is added to a nylon nonwoven fabric to form a non-breathable inner bag. Materials used in conventional disposable body warmers, such as laminated ones, can be used without any restrictions. The outer bag is not particularly limited as long as it is non-breathable.

As described above, in the heating mat of the present invention, it is possible to use cheap tin iron, which could not be used in the past, as the iron component, and not only the surface of the iron powder but also the iron inside can be subjected to the reaction. A heating mat can be provided at an extremely low cost.

In the heating mat of the present invention, the heat generation is controlled by the size and number of holes in the inner bag, the oxygen uptake ability of the carbonaceous material, and the ratio of the conductive carbonaceous material to the porous material as described above. can do.

The above explanation has mainly been given to the case where the heating mat is used as a heating element such as a hand warmer, but the heating mat of the present invention is not limited to these applications. The present invention can be applied to various heating purposes without departing from the spirit of the present invention for uses such as anchors, etc. In other words, suitable objects to which the present invention can be applied include, for example, cans, etc. These include bottled beverages and foods, retort pouch foods, and other devices such as thermal storage anchors and battery antifreeze devices.

Next, the heating mat of the present invention will be explained with reference to production examples, working examples, and comparative examples, but the present invention is not limited only to these examples.

Production examples 1 to 5 Cement (ordinary Portland cement (J-K5R521)
0), manufactured by Koshuda Cement ■) 8. Add 17 m9 of aluminum powder as a foaming agent to 59, add carbon black powder (acetylene black 1) in the amount shown in Table 1, and add 9 m9 of water.
Add 30 g of iron powder (g and Cassie chloride as a hardening accelerator) to the kneaded material, mix thoroughly with iron powder, and after curing for 48 hours, grind and coat each iron powder with a conductive porous layer (particle size 7 mesh bath). I got it.

Examples 1 to 5 The iron powder ASG coated with the conductive porous layer obtained in Production Examples 1 to 5, respectively, and 9 g of ice were filled into an inner bag.

The inner bag is a polypropylene sheet (thickness 0, o5ia
ms 15om x 12om) with a diameter of 0
・One hundred 7 mm holes were used on both sides.

Immediately after filling, the inner bag was kneaded several times and placed in a moisturizing bag made of a blanket to measure changes in the humidity of the mat. The atmospheric temperature was room temperature.

The results are shown in Table 1.

Comparative Example 1 The inner bag was filled in the same manner as in Example 1, except that the iron powder used in Production Example 1 was used instead of the iron powder coated with a conductive porous layer, and the temperature change was measured in Example 1. Measurement was carried out in the same manner as in 1.

The results are shown in Table 1.

Comparative Example 2 An inner bag was filled in the same manner as in Example 1 except that reduced iron powder was used instead of iron powder coated with conductive porous material, and the temperature change was measured in the same manner as in Example 1. did.

The results are shown in Table 1. Table 1 As is clear from Table 1, when uncoated ordinary iron powder was used, almost no heat was generated.
By coating with a conductive porous layer, it generates heat to the same degree as that using reduced iron powder, and as the amount of carbon black added increases, both the duration and rise time are longer than those using reduced iron powder. It can be seen that this has also been improved.

Example 6 In addition to the components used in Example 1, FeS was added as an initial exothermic agent.
The exothermic state of the mixture containing 04.7H2049 and 22g of 0&(OH) was compared.

The inner bag is first filled with coated iron powder and FeS.
This is done by putting the mixture with O4.7H20 into the inner bag, then putting the mixture of other ingredients and Oa(OH)2 into the remaining space of the inner bag, and firmly heat-sealing the opening of the inner bag. Ta.

After thoroughly mixing both components by shaking several times, the temperature was varied in the same manner as in Example 1.

As a result, the temperature reached 40°a after 9 minutes, and 1 &
A high temperature of 64°O was achieved and maintained at 48°O for approximately 21 hours. It remained above 4000 for about 22 hours.

Comparing this result with the result obtained in Example 1, the rise in temperature is markedly different from IF@804.7H20 and 0a(OH
)2 is faster.

Claims (1)

[Scope of Claims] 1. A heating pine comprising a bag containing a mixture of iron powder coated with a conductive porous layer, an electrolyte aqueous solution, and a carbonaceous material. 2. The heating mat according to claim 1, wherein the conductive porous layer is a cement layer containing carbon black powder.