JPH04293989A - Manufacture of heat generating composition - Google Patents

Abstract

PURPOSE:To improve the flowability of the raw material for a heat generating composition consisting of a metal powder, a halide, water, and a water absorption aid and to prolong the persistence of heat generation without any increase in volume. CONSTITUTION:Manufacture of a heat generating composition wherein a composition for generating heat through hydroxylation of a metal powder, consisting of a metal powder, a halide, water, and a water absorption aid, in which the water is in an amount of 55-70 pts.wt. based on 100 pts.wt. metal powder and the water-absorptive base material, is in an amount sufficient to retain the added water, is granulated to provide a mean particle diameter of at least 0.5mm after the base materials are mixed; and manufacture of the heat generating composition wherein 10-20 pts.wt. tacky binder component is incorporated into the added water to improve the strength of the granulated particles. As compared with conventional heat generating agents, the persistence of heat generation can be prolonged about 1.5-fold, about 10% increase in productivity can be realized, and troubles in discharging from a hopper and in filling can be prevented.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for producing a heat-generating composition used in so-called disposable hand warmers, etc., in which iron powder generates heat through the reaction with water and oxygen, and in particular, to improve the heat-generating properties and extend the duration of the heat generation. The present invention relates to a method for producing a heat-generating composition.

0002

BACKGROUND OF THE INVENTION It has been well known that iron powder reacts with water and oxygen to form iron hydroxide. In order to promote the hydroxylation reaction of iron, metal halides, which have a lower ionization tendency than iron, are added as catalysts, allowing the reaction to occur more rapidly than normal hydroxylation reactions, and utilizing the heat of this reaction. So-called disposable body warmers for warming the human body are generally available.

[0003] Many proposals have been made for these exothermic compositions, and Japanese Patent Application Laid-Open No. 105562/1983 discloses a composition containing iron powder and a reaction aid as main components that generates heat in the presence of water and oxygen. A method has been proposed in which activated carbon having a particle size of 104 μm or less and containing water is mixed with the exothermic composition to prevent separation of the iron powder and activated carbon, resulting in a uniform exothermic reaction. ℃, the maximum temperature is 5 when the duration is 121 minutes over 50℃ and the weight is 100g.
The duration is 22 hours at temperatures above 8°C and 50°C, and the duration is extended by increasing the weight of the raw materials. In this case, the moisture content is at most 5 parts by weight per 100 parts by weight of metal powder.
It was 0% by weight.

Furthermore, JP-A No. 50-40477 proposes an exothermic composition containing iron and metal chlorides as active ingredients that generates heat by reacting with water and oxygen, and which can provide a higher temperature. A temperature of 160°C was obtained. Furthermore, in Japanese Patent Publication No. 61-8116, in addition to activated carbon impregnated with iron powder, chloride, and water, one or more of manganese dioxide, cupric oxide, and triiron tetroxide are appropriately mixed to improve air permeability. A metal heating element placed in a certain wrapping bag was shown, and a method was proposed for improving the temperature rising characteristics and making the reaction uniform.In this case, the total weight of the material was 35g, and the maximum water content was 35g. of 28.5% by weight, and the duration at 50°C was up to 400 minutes. As described above, in the conventional method, the duration of heat generation is about 2 hours when converted to 10 g of material.

[0005] The characteristics of these exothermic compositions when manufactured and used as disposable hand warmers are specified in JISS 4100, and include a maximum temperature of 70°C or less, a rise time to 40°C within 20 minutes, and a sustained temperature of 40°C or higher. The time is longer than the displayed time. In order to satisfy this condition, the conventional method involves adjusting the air permeability of the packaging bag filled with the exothermic composition, controlling the amount of oxygen supplied to keep the maximum temperature below 70°C, and determining the duration of the reaction by the weight of the iron powder to be reacted. A simple method has been used to extend the period by increasing . However, in such a property control method, the weight of the filler increases significantly, resulting in an increase in the raw material consumption rate and, in turn, an increase in manufacturing costs. In addition, there are issues related to increases in storage, transportation, and packaging material costs due to increases in weight and volume.Furthermore, as the weight of the equipment for filling bags increases, the time required to cut them increases, which reduces productivity. However, there was a problem in that the manufacturing cost of the product decreased and the manufacturing cost of the product increased, and it was not fully satisfactory in practical terms. In addition, the raw material is fine powder with moisture added, and its poor fluidity reduces cutting accuracy, increases weight variation, and causes sealing failures due to material getting caught in the heat-sealing surface when filling bags. There were also issues such as:

[0006]

[Problems to be Solved by the Invention] In view of the above problems, the present invention sets the maximum temperature and rise time to the upper limit within the JIS range, obtains the maximum duration, reduces the filling volume, and reduces storage and transportation costs. The purpose of the present invention is to provide a method for producing a heat-generating composition that improves problems such as reduction in heat, weight variation, and poor sealing, and achieves a reduction in production costs.

[0007]

[Means for Solving the Problems] The present invention was made as a result of various experiments and studies regarding the exothermic reaction of hydroxylation of iron powder. In an exothermic composition that generates chemical reaction heat by reacting with oxygen in the atmosphere, which is made of a water absorption aid containing low metal halide and moisture, the proportion of moisture is 55 to 70 parts by weight per 100 parts by weight of metal powder. Then, adjust the water absorption aid to a weight that can absorb the blended water according to its ability, reduce free water, and mix the raw materials. A method for producing a heat-generating composition characterized by granulating and granulating it into particles, and a method for producing a heat-generating composition characterized by blending 10 to 20% by weight of a water-soluble sticky material in added water. It's in the method.

Metal powders used in the present invention include reduced iron powder produced by reducing ores, etc., atomized iron powder produced by spraying from a solution, and cast iron produced by crushing cast iron materials as raw materials. Any commonly produced metal powder such as powder or high-purity electrolytic iron powder can be used, and there is no particular limitation as long as the material is oxidized by iron hydroxidation reaction and absorbs oxygen. Halides include NaCl, KCl, NaBr,
Alkali metal halides such as KBr, MgCl, Ca
Cl2, CaBr2, MgBr2, BaBr2,
halides of alkaline earth metals, and also AgCl2
, ZnCl2 , AlCl3 , SnCl2 , Mn
Cl2, FeCl2, FeCl3, CoCl2
, NiCl2 , CuCl2 , ZnBr2 , SuB
Various metal halides such as r2, FeBr2, CuBr2, etc. can be used. Here, the halide used is a material that can promote the hydroxylation reaction of iron powder.
The material is not particularly limited as long as it has a lower ionization tendency than metal powder.

[0009] Also, as an absorption aid, water or water in which a halide is dissolved can be retained internally, and when mixed with metal powder, water absorption can be maintained to the extent that the added water does not cover the surface of the iron powder. There are no particular limitations as long as the material is
Mineral materials such as vermiculite and zeolite, adsorbent materials such as activated carbon and silica gel, and even water-absorbing silica,
Synthetic products such as water-absorbing resins can be used alone or in combination.

[0010] These materials undergo an exothermic reaction when mixed uniformly, but because they are fine powders and contain moisture, the fluidity of the raw materials is poor, making it difficult to cut them out from inside the raw material holding hopper or from inside the wrapping bag. Problems such as clogging and getting caught in the sealing surface of the package were likely to occur when filling the bag. For this reason, in the present invention, 0.5 mm of water is added without evaporating the added water.
The exothermic composition is granulated to give fluidity to the exothermic composition in order to form granules with the above particle size. The granulator used in this case can perform mixed granulation using methods such as rolling, fluidization, centrifugation, and stirring, or forced granulation using compression and extrusion methods, and water added during the granulation process is reduced by evaporation, etc. The granulation method and type are not particularly limited as long as the granulation method is not used. During this granulation, it is more preferable to keep the atmosphere inside the granulator inert or under reduced pressure in order to prevent the preliminary reaction of the exothermic agent. In particular, by dissolving the sticky material as a binder in the added water, granulation can be carried out more efficiently and products with high strength can be obtained.

The binders used here include liquid inorganic binders such as water glass, polyvinyl alcohol (P
Organic water-soluble materials such as VA), carboxymethylcellulose (CMC), hydroxypropylcellulose (HPC), and polyvinylpyrrolidone (PVP) can be used by dissolving them in water, which will eventually make the granulation process easier. ,
It is not particularly limited as long as it increases the granule strength after granulation and does not inhibit reactivity. Since the material manufactured in this way is in granular form even with a high moisture content, it has sufficient fluidity compared to powdered exothermic compositions, and can be cut out and weighed with high precision and in a short time. There is no clogging of the hopper or the like, and there is no clogging of the heat-sealing surface after the heat-generating composition is filled into the package, and the product can be manufactured with high productivity.

The present invention will be explained in detail below based on embodiments. The exothermic composition produced according to the present invention undergoes a hydroxylation reaction in the presence of iron powder, water, and oxygen to generate heat. This reaction requires oxygen in the atmosphere and moisture added to the raw materials. Here, oxygen is sufficiently present in the atmosphere, and there is almost no possibility of interrupting the exothermic reaction unless the user intentionally does so. On the other hand, water can only participate in the reaction if it is mixed into the raw materials, and considering the evaporation loss from the wrapping bag due to the heat generation agent itself being heated during use, the amount of water required for a complete reaction of 1 g of iron powder is It was found that a large amount of water, 0.25 g or more, was required to be added.

[0013] From this result, it cannot be said that the blending ratio of water blended in conventional exothermic compositions is sufficient, and as a result of analyzing the iron powder as the base material after the reaction, it was found that the metallic Fe content was 20 to 3.
It was found that 0% by weight remained. For this reason, when a small amount of water was again added to the base material after use, the exothermic reaction continued. From this, it was found that the iron powder contained in the mixture did not completely react and was not fully utilized. The free water that cannot be absorbed wets the surface of the iron powder and inhibits the reaction, and the compounded ingredients almost no longer generate heat.Furthermore, the raw material is sticky as a whole, and when it is cut from the hopper,
It was difficult to manufacture using mass production equipment due to the problem of not being able to smoothly fill the packaging.

[0014] As a countermeasure against this problem, an increase in water absorption aid is added in response to the increase in water content. In the exothermic composition produced under such conditions, the exothermic reaction proceeds efficiently as the water content increases, but in this case, the volume of the exothermic composition increases, leading to a decrease in filling speed and filling properties, which is not necessarily desirable from an industrial perspective. This is not a manufacturing method, and it increases the filling weight and volume of the entire raw material, so it is not necessarily a preferable method for commercial products.

From this point of view, the present invention adds more water than conventional agents in order to effectively utilize the iron powder used, so that water does not cover the surface of the iron powder and inhibit the reaction. The blending ratio of the water absorption aid is increased according to its ability so that it absorbs the water blended as above, and after mixing these raw materials, it is made into granules with a size of 0.5 mm or more under conditions that the blended water does not decrease. By granulating the pyrogen, the bulk density of the pyrogen is increased, suppressing the increase in volume caused by increasing the amount of water and water-absorbing material, and improving the fluidity of the pyrogen to prevent clogging of the hopper and filling the packaging bag. This is an attempt to improve sex.

As an example of this, 28.5 g of reduced iron powder with an average particle size of 65 μm produced by reducing iron ore as metal powder,
An exothermic composition was prepared by mixing 1.5 g of NaCl as a halide, 14 g of activated carbon as a water absorption aid, and 16 g of water, and the characteristics thereof will be explained based on the results of investigation. This composition has 5 g more water and 5 g more water absorption aid than the conventional formulation, so the volume has increased due to the increased blend of water absorption aid and water. However, this raw material was replaced with Ar gas in advance to reduce the oxygen concentration to 1 vol% or less using a batch-type closed system high-speed mixing tumble granulator (Fuji Paudal Spartan Reuser: Model 6H). In this state, granulation was started. First, add 50% of the target moisture for 5 minutes and mix, then add the remaining moisture and mix for 4000 r.
Granulation treatment was carried out at a high speed of pm to form spherical granules containing water and having an average particle diameter of about 0.5 mm. Here, the bulk density of the exothermic element produced by simply mixing water and a water absorption aid is 0.66 g/cm3, and the bulk density after granulation is 1.0.
0g/cm3, and the bulk density could be increased by 50% by granulation. As a result, the occupied volume of the exothermic composition with the conventional formulation is 75 cm3, the occupied volume of the mixed powder with simply increased water and water absorption aid is 91 cm3, and the occupied volume of the exothermic agent after granulation is 60 cm3. The volume occupied by the exothermic composition produced by the method of the present invention was reduced by 20% compared to conventional compositions, even though the weight increased by 10 g, and the filling performance into packaging bags was improved. .

The reason why the density of the exothermic agent is improved by granulation is that during the granulation process, the powders that are the raw materials for the exothermic composition adhere more tightly within one granulated particle, which reduces the internal air space. It has increased density. Furthermore, when a heat-generating composition in the form of a mixed powder was manufactured using industrial-based automatic equipment, clogging of the hopper and raw materials getting caught in the packaging seal area occurred; There were almost no problems and the product was manufactured with high productivity.

[0018] The exothermic properties of this exothermic composition were determined according to JIS S
Figure 1 shows the results of the investigation according to 4100. When the conventional exothermic composition containing 50g of formulation has a maximum temperature of 68 to 70℃, the duration of 40℃ or higher is 15 hours, and the duration per 10g of exothermic agent is 3.0 hours, and the maximum temperature is 68 to 70℃.
The above duration was also about 2 hours. On the other hand, 60 g of the exothermic composition with increased moisture content of the present invention has a maximum temperature of 68 to 70°C, and the duration of the temperature above 40°C is about 24 hours, and the duration per 10 g of the exothermic composition is about 4 hours. As a result, the duration was significantly improved. As a comparative example, we showed the exothermic properties when only the water content was increased to 16 g without changing the formulation of the aqueous auxiliary agent, but the maximum temperature rose only to about 40°C and it could not be applied as a heat generating composition for disposable hand warmers. Ta.

As a result of analyzing the iron powder after the reaction of this exothermic composition, it was found that the conventional exothermic composition contained 32% by weight of metallic Fe.
However, in this method, the amount was only 7% by weight, indicating that the reaction efficiency of iron powder was significantly improved by the present invention, and as a result, the duration of heat generation was extended. Furthermore, when the exothermic composition was granulated to a size of 0.5 mm or more, it exhibited exothermic characteristics similar to those of the exothermic composition containing a high moisture content.

[0020] As a result of such studies, if the water content is less than 55 parts by weight per 100 parts by weight of metal powder, the iron powder will not react effectively and a large amount of unreacted material will remain, resulting in a shortened duration and 70 parts by weight. Since the reaction efficiency of the iron powder will not be improved and the duration will not be significantly extended even if the amount is more than 100 parts by weight, the water content should be 55 to 70 parts by weight per 100 parts by weight of the metal powder. It is in the upper preferred range. The particle size after granulation is 0.
If the diameter is smaller than 5 mm, there will be more contact between particles, which will reduce fluidity, and increase the probability of clogging in the hopper and clogging of the heat seal part during filling into the packaging bag, so the particle size after granulation may be reduced. must be 0.5 mm or more. There is no particular upper limit on the particle size, but as the granulated particles become larger, the number of particles decreases even if the overall weight of the heat-generating composition remains the same, and when it becomes lumpy, the contact area with the human body decreases, making it difficult for heat to be transmitted effectively. . For this reason, a range of so-called general granules is preferred.

[0021] By blending an adhesive binder into the water added during granulation, the adhesion between particles during granulation is improved, granulation can be easily performed, and the strength of the particles after granulation can also be increased. The binder concentration that exhibits this effect is preferably 10 to 20% by weight in an aqueous solution, and 10% by weight.
At a concentration lower than that, the effect of adding the binder is hardly seen and the effect of imparting tackiness to the granulated particles does not appear. On the other hand, if the amount is more than 20% by weight, the binder component inhibits the exothermic reaction, so it is specified from the exothermic reaction aspect, and the binder cost increases, so it is not economical, so an upper limit is specified.

[0022]

[Example] Examples will be described below. [Example 1] Reduced iron powder obtained by reducing iron ore as iron powder was used as 2
8.5g, 1.5g of NaCl is used as the halogen metal, the weight of water is 11, 14, 16, 20, 24g, and activated carbon is added as a water absorption aid from 9g to 22g to match the increase in water content. to prevent the entire pyrogen from becoming sticky. This exothermic agent was heated in a high-speed rolling granulator with 50% of the added moisture in the granulator with Ar purge inside the granulator and the atmosphere reduced to an oxygen concentration of 1 vol% or less.
After uniformly mixing for 5 minutes at rpm, increase the rotation speed to 4000.
A granulation process was carried out by spraying the remaining water at a high speed of 100 rpm for 10 minutes to produce a heat-generating composition with an average particle size of 0.5 mm. A disposable body warmer was manufactured by using this heat-generating composition as a packaging bag made of a breathable material having ventilation holes in which the inner surface of a non-woven fabric was laminated with polyethylene and the surface was made of nylon spunbond, and was filled with a granulated heat-generating agent. Table 1 shows the results of investigating the heat generation characteristics of this body warmer according to JIS.

[0023]

[Table 1]

[0024] The maximum temperature is 68~ by adjusting the air permeability of the wrapping bag.
When heated to 70℃, the duration of the temperature is 40℃ or more, clogging of raw materials,
We checked the problem of raw materials getting caught in the seal part of the packaging bag, but if we increased the amount of water absorption aid as the amount of water added and performed granulation, there would be no manufacturing problems and the duration would be extended. Added 16g (63g per 100 parts by weight of iron powder)
(parts by weight), the duration of temperature at 40°C or higher reached 24 hours. Furthermore, add 20g of water (70g per 100 parts by weight of iron powder).
The duration reached 24.5 hours when the water content was increased to (parts by weight), but there was no clear increase in the duration when more water was added, and on the contrary, when the water content was reduced to 11 g or less, the duration reached 24.5 hours. It was shortened to about an hour. Here, even if the water content is increased, if the water-absorbing material composition is kept constant at 9 g, the water content is 16 g.
When the temperature of the exothermic agent increases to 1.5 g, even if the ventilation of the packaging bag is adjusted, the exothermic temperature is only about 40°C, which is not practical at all, and the exothermic agent often fails to cut out and gets caught in the sealing part of the packaging bag.

[Example 2] 28.5 g of reduced iron powder obtained by reducing iron ore was used as iron powder, and 1.5 g of NaCl was added to the halogen metal.
Using 5g, the combined weight of water was 16g, and J was added to this water.
IS No. 2 water glass was mixed at concentrations of 5, 10, 15, 20, and 25%, and as the water content increased, 14 g of activated carbon was added as a water absorption aid to prevent the entire exothermic agent from becoming sticky. did. After purging the inside of the granulator with Ar and reducing the atmosphere to an oxygen concentration of 1 vol% or less, 50% of the added moisture was added to the exothermic agent in a high-speed rolling granulator, and the mixture was uniformly mixed at 2000 rpm for 5 minutes. Then, the remaining water was added by spraying at a high rotation speed of 4000 rpm for 5 minutes to perform granulation, thereby producing a heat-generating composition with an average particle size of 0.5 mm. A disposable body warmer was manufactured by using this heat-generating composition as a packaging bag made of a breathable material having ventilation holes in which the inner surface of a non-woven fabric was laminated with polyethylene and the surface was made of nylon spunbond, and was filled with a granulated heat-generating agent. Table 2 shows the results of investigating the heat generation characteristics of this body warmer according to JIS.

[0026]

[Table 2]

When the binder concentration in the added water is 20% or less, the target granules can be obtained in 5 minutes of granulation time, which is half the time compared to the condition where no binder is added. Ta. The exothermic characteristics showed almost the same characteristics as in Example 1, and no change in the exothermic characteristics was observed due to the binder formulation.
% combination, the duration was slightly shortened. This is thought to be because the binder component, which does not contribute to the reaction, prevents the iron powder from coming into contact with air, and the upper limit of the binder addition concentration is preferably 20% by weight. When the binder concentration of the aqueous solution is 5%, some powder remains after 5 minutes of granulation, and the strength improvement effect of the granulated product is not clear, and the fluidity is also lower than when 10% by weight or more is added. Lower binder concentration to 10% by weight
Under the above conditions, the strength after granulation is higher than that without addition, and there is almost no collapse of the granulated particles when cut and filled.
Cutting out from the hopper and filling performance were improved, and productivity was improved by 10% compared to the conventional powder filling method.

[0028]

Effects of the Invention The present invention is an exothermic composition produced by the hydroxylation reaction of metal powder, which is composed of metal powder, a halide, water, and a water absorption aid. The fluidity of the exothermic element is improved by making it 0.5 mm or more by means such as forced granulation, which is caused by the reaction and the decrease in fluidity of the exothermic element due to an increase in the water content. As a result, the duration of the exothermic composition has been extended to about 1.5 times compared to conventional ones, and the ability to cut it out from the hopper and fill it into air-permeable bags through granulation has been improved, resulting in a 10% increase in productivity. The granulation increases the density of the exothermic agent, and the exothermic composition does not increase in volume compared to conventional agents, making it easier for the exothermic composition to flow even within the package, making it easier to adhere to the object when manufacturing disposable body warmers. This is an effective invention that can efficiently transmit the generated heat.

[Brief explanation of the drawing]

FIG. 1 is a comparison diagram of the heat generation characteristics of the conventional method and the method of the present invention.

Claims (2)

[Claims] Claim 1: A method for producing a heat-generating composition that generates heat of chemical reaction by reacting with oxygen in the atmosphere, comprising a metal powder, a metal halide with a lower ionization tendency than the metal powder, and a water absorption aid containing water. , the proportion of water is 55 to 70 parts by weight with respect to 100 parts by weight of metal powder, a water absorption aid is blended according to its ability to make the weight capable of absorbing water, free water is reduced, and the raw materials are mixed. A method for producing a heat-generating composition, which is then granulated into particles having an average particle diameter of 0.5 mm or more under conditions that do not reduce moisture content. 2. The method for producing a heat generating composition according to claim 1, wherein 10 to 20% by weight of a water-soluble adhesive material is blended into the added water.