JP3778213B1 - Pyrogen - Google Patents

Abstract

SOLUTION: Soda lime, calcium oxide or a mixture of soda lime and calcium oxide is added to an aluminum metal powder, and a solid phase reaction is performed by stirring at room temperature, and the soda lime or soda lime is mixed with the surface of the metal or alloy powder. An exothermic agent in which the metal or alloy powder is included by a thin film formed by a solid phase reaction with a calcium oxide mixture.
[Effect] It is possible to provide a heat generating agent mainly composed of aluminum metal powder having a heat generation start time of 10 to 20 seconds, a water vapor maximum temperature of 100 ° C, a holding time of 20 to 30 minutes, and a water vapor pH of 7.5 to 8.0. it can.
[Selection figure] None

Description

  The present invention relates to a heat generating agent in which a metal or alloy powder such as aluminum is included in a film which is stable in the air but dissolves quickly in water.

  As is well known, pure metals generally form an oxide film with oxygen and moisture in the air, and therefore metals such as potassium, sodium, calcium, magnesium, aluminum, zinc, iron, especially these finely divided metals. Is easy to make oxide film.

  However, of these, oxide films of metals other than aluminum, zinc, and iron are highly soluble in water, so they dissolve quickly even with a small amount of water, exposing a pure metal surface, and react with oxygen or moisture in the atmosphere when warm. To do. For this reason, these metals have a large calorific value and are expected as raw materials for heat generating agents, but cannot be stored in the atmosphere, and are therefore difficult to use as heat generating agents.

  In contrast, exothermic agents utilizing exothermic reactions of chemical substances are those by reaction with water with anhydrous oxides such as calcium oxide and anhydrous salts such as calcium chloride, aluminum and zinc metal powders, and magnesium-iron compounds. Proposed by reaction of powder and water, by reaction of powdered lime, powdered aluminum and water (Patent No. 3467729, US Patent Registration No. 6200357, European Patent Registration No. 1126004, Korea) Patent registration No.0407582).

  Among these, the exothermic agent due to the reaction of aluminum and zinc metal powder and magnesium-iron compound powder with water utilizes the heat of reaction when reacting with water on the surface of metal powder such as aluminum.

  In addition, the exothermic agent by the reaction of powdered quicklime, powdered aluminum and water generates calcium hydroxide by the reaction of powdered quicklime and water as the first stage, and uses this reaction heat as the second stage. It reacts with powdered aluminum and calcium hydroxide to generate heat of reaction.

That is, in this type of exothermic agent, the solution temperature is raised by a preliminary reaction of anhydrous calcium oxide and water, and the heat generated by the reaction and the full-scale heat generation by the reaction of calcium hydroxide and aluminum occur.
Patent No. 3467729, U.S. Patent Registration No. 6200357, European Patent Registration No. 1126004, Korean Patent Registration No. 0407582, Japanese Patent Application No. 10-254402, Japanese Patent Application No. 5-209233, Japanese Patent Application No. 6-274162, Japanese Patent Application No. 5-89380

  However, any of the exothermic agents utilizing the exothermic reaction on the surface of the metal powder such as aluminum and zinc has a drawback that it takes a long time to start the heat generation.

  This is because an aluminum or zinc oxide thin film, which is relatively stable against oxygen and water, is formed on the surface of the aluminum or zinc metal powder, which is removed and the surface of the metal powder is exposed to start an exothermic reaction. Takes a long time to complete. In particular, aluminum oxide has extremely low solubility in water, and it takes a considerable amount of time to be removed and to start an exothermic reaction on the surface of the aluminum metal powder.

  In view of the above circumstances, the present invention adds soda lime, calcium oxide or a mixture of soda lime and calcium oxide to a metal or alloy powder, and stirs at room temperature to cause a solid-phase reaction to form on the surface of the metal or alloy powder. The present invention proposes an exothermic agent in which the metal or alloy powder is included by a water-soluble film.

  That is, in the present invention, which is fundamentally different from the above-described prior art, a stable oxide film formed on the surface of a metal powder such as aluminum or zinc and a basic oxide such as soda lime or a mixture of soda lime and calcium oxide. A surface solid phase reaction is performed while stirring and mixing at room temperature, and a water-soluble film that is relatively stable in the air but easily dissolved by water is formed, and the metal powder is included by these films.

The reaction in this case proceeds as follows, for example.
AL ₂ O ₃・ AL + Na ₂ O ・ CaO → [NaALO ₂ + Ca (ALO ₂ ) ₂ ] ・ AL

Here, AL ₂ O ₃ · AL represents an aluminum oxide film formed on the surface of the aluminum metal powder, and [NaALO ₂ + Ca (ALO ₂ ) ₂ ] indicates that the aluminum metal fine powder after the reaction is [NaALO ₂ + Ca ( ALO ₂ ) ₂ ] represents a state of inclusion in a thin film.

The [NaALO ₂ + Ca (ALO ₂ ) ₂ ] coating produced by stirring and mixing solid-phase reaction is different from the aluminum oxide coating in that it is relatively stable in the atmosphere, but it is easily dissolved by water and has high reaction activity. Expose the surface.

This pure aluminum metal with high reaction activity can react violently with water and generate high heat in a short time, and its reaction formula is as follows.
2 [NaALO ₂ + Ca (ALO ₂ ) ₂ ] ・ AL + 3H ₂ O
→ 2Na ⁺ + 2ALO ₂ ⁻ + 2Ca ²⁺ + ALO ₂ ⁻ + 2AL + 3H ₂ O
↑
2AL + 3H ₂ O → AL ₂ O ₃ + 3H ₂

  As the aluminum or zinc metal powder that can be used in the present invention, a commercially available metal powder can be used, but in order to increase the calorific value, it is preferable to have a purity of 98% or more and a particle size of 20 μm to 120 μm.

  That is, the conventional heat generating agent using aluminum or zinc has a problem in that the oxide film formed on the surface thereof is stable against water and difficult to be wetted by water, so the purity limit and the particle size limit are severe. Then, since a water-soluble film is formed by a solid-phase reaction, the purity and particle size of the aluminum or zinc metal powder have the advantage that they are not so important factors.

  Further, the soda lime and calcium oxide powder used in the present invention may be general commercial products, and further, it is not necessary to specify the particle size as long as it can ensure the surface solid phase reaction with the aluminum metal powder, preferably Those having a purity of 85% or more and 50 μm-200 μm are convenient for actual reaction.

  In addition, the basic reaction principle of the exothermic agent of the present invention is to enclose the surface of the metal fine powder with a water-soluble coating so that the storage safety in air is relatively high and the reaction with water takes place in a short time. In order to satisfy this requirement, the water-soluble film needs to be about 0.1 to 1 wt% with respect to the surface of the metal powder. Based on this, the amount of soda lime and soda lime-calcium oxide is calculated in a chemical equivalent. However, it is required to form a water-soluble film.

  The mixing ratio of soda lime and calcium oxide is arbitrary, but soda lime / calcium oxide = <30/70> wt% is preferable.

  In addition to the aluminum powder, aluminum alloy powder, zinc powder, zinc alloy powder, or the like can be used as the metal powder used in the present invention.

The exothermic agent of the present invention exhibits the following effects.
(1) Unlike the type that generates heat of reaction by reacting with powdered aluminum and calcium hydroxide produced in the first stage as the second stage reaction using the heat of reaction between the powdered quicklime and water described above, A water-soluble basic thin film, that is, sodium aluminate and calcium aluminate film is formed by stirring solid phase reaction of the inert aluminum thin film formed on the surface of the aluminum metal fine powder with soda lime or soda lime-calcium oxide mixture, High heat can be obtained instantaneously by realizing a direct reaction between water and active metal aluminum by quickly dissolving in water.

(2) Compared to conventional exothermic agents, the active surface of aluminum metal fine powder is formed in an aqueous solution in a short time.
Since the amount of water added is small, the maximum water vapor temperature can reach 98-100 ° C in a short time of 10 to 20 seconds, and the temperature can be maintained for 20 to 30 minutes. The water vapor pH is 7.5 to 8.0, and there is no problem with toxicity.

  (3) The heat-generating agent according to the present invention is lightweight, has a storage safety and has a high heat-generating effect, so that it is used for outdoor heating agents, emergency heating agents for natural disasters such as earthquakes, ocean, mountain behavior, sports training, etc. It can be used widely as a heating agent that can be used in foods to be carried.

  Add soda lime, calcium oxide or a mixture of soda lime and calcium oxide to aluminum metal fine powder, stir at room temperature to cause a solid-phase reaction, and form an aluminum metal by a water-soluble basic thin film formed on the surface of the metal fine powder. An exothermic agent that encloses fine powder.

Examples of the present invention will be described below. In addition, this shows one Example of invention, This invention is not limited to this Example.
Example 1
22 g of soda lime was added to 500 g of metal aluminum fine powder having a purity of 99.7%, and a stirring solid phase reaction was carried out for 30 minutes under a temperature of 20 ° C. to 23 ° C. During the stirring solid phase reaction, the reaction vessel temperature was 35 ° C. to 40 ° C. depending on the heat of reaction.

Example 2
30 g of a soda lime-calcium oxide (5/95 wt%) mixture was added to 500 g of metal aluminum fine powder having a purity of 99.7%, and a stirring solid phase reaction was performed for 30 minutes at a temperature of 23 ° C. to 25 ° C. During the stirring solid phase reaction, the reaction vessel temperature was 40 ° C to 42 ° C.

Example 3
50 g of soda lime was added to 500 g of metal aluminum fine powder with a purity of 98%, and a stirring solid phase reaction was carried out for 1 hour. During the stirring solid phase reaction, the reaction vessel temperature was 40 ° C to 45 ° C.

Example 4
Reaction conditions: Use aluminum fine powder (purity 99.7%), soda lime, calcium oxide (commercial first grade particle size 1mm) at a mixing ratio of 5 / 95wt% to make a solid phase reaction, this solid phase reaction generated 50 g of each product was weighed and filled into a paper and non-woven bag (length: 150 mm, width: 50 mm) resistant to heat generation to produce a heat-generating packaging agent. When this exothermic agent was put in a heat-resistant container and 90 mL of water was added, an exothermic reaction started 10 seconds later. Table 1 shows the results of measuring the generated water vapor temperature and the water vapor temperature holding time.

  As a result, the aluminum metal fine powder and soda lime and soda lime-calcium oxide powder are stirred and mixed by solid-phase reaction, so that the heat generation start time, the maximum water vapor temperature, and the retention time up to 80 ° C. are higher than those of conventional aluminum heating agents. It was confirmed that it has excellent performance.

  Unlike the prior art, the generated steam has a pH of 7.5 to 8.6, which is low alkaline and safe. This is due to the small amount of basic oxide used.

Claims (3)

A soda lime, calcium oxide or a mixture of soda lime and calcium oxide is added to the metal or alloy powder, and a solid phase reaction is performed by stirring at room temperature, and the metal or alloy powder is formed by a water-soluble film formed on the surface of the metal or alloy powder. An exothermic agent characterized by including an alloy powder. The heat generating agent according to claim 1, wherein the metal or alloy powder is aluminum or zinc metal or alloy powder. The exothermic agent according to claim 1, wherein when the exothermic agent is mixed with water, an exothermic reaction takes place in a few seconds and the maximum water vapor temperature is 100 ° C.