JPH09100468A - Persistent cooling agent and method for producing the same - Google Patents

Abstract

(57) Abstract: A cooling agent that cools by mixing a cryogen that does not contain water of crystallization and a cryogen that contains water of crystallization has a long cooling ability. SOLUTION: One or both of a cryogen containing no water of crystallization and a cryogen containing water of crystallization are supported on a porous body to reduce the contact area of the cryogen. Alternatively, the surface of the cryogen containing water of crystallization is coated with a polymeric substance, and the viscosity of the solution produced when the cryogen is dissolved is increased by the polymeric substance. Due to the reduction of the contact area of the cryogen and the infiltration of the produced solution, the duration of cooling capacity becomes longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling agent that utilizes an endothermic phenomenon that occurs when a cryogen is dissolved or brought into contact with water, and more specifically, a cryogen that does not contain water of crystallization and a cryogen that contains water of crystallization. The present invention relates to prolonging the cooling ability duration time of a cooling agent which is brought into contact with and cooling.

[0002]

2. Description of the Related Art There is a cooling agent which utilizes an endothermic phenomenon which occurs when a cryogen composed of an inorganic salt such as ammonium nitrate is dissolved in water or when the cryogen absorbs water. Since such a coolant can cause an endothermic phenomenon at any time, it can be conveniently used as a portable coolant. When used as a portable cooling agent, the particles of the freezing agent and the particles of water or a substance containing water are separated in advance, and both are mixed immediately before use.
For example, the inner bag and outer bag are separated by double packaging, and the inner bag and outer bag particles are brought into contact with each other by hitting or bending the package to rupture the inner bag and start heat absorption. There are known products that let you.

As the substance containing water, a hydrate, that is, a compound containing water of crystallization is used. The cryogen that has absorbed water of crystallization from a compound containing water of crystallization dissolves into a liquid. In addition, a part of the cryogen supplied with water of crystallization is also dissolved. The dissolved solution in which these are mixed infiltrate into the cryogen that does not contain undissolved water of crystallization, and all the cryogen absorbs water. Therefore, the cooling in the case where the particles of the cryogen that does not contain water of crystallization and the particles of the cryogen that contains water of crystallization are brought into contact with each other is as follows: And the dissolution of the cryogen, and (2) infiltration of the cryogen solution into the cryogen particles and absorption and dissolution of the cryogen particles in water.

[0004]

However, inorganic salts, which have the property of absorbing heat when dissolved, generally have a high dissolution rate in water. For this reason, the cooling agent of the method of dissolving the cryogen in water has a problem that the cryogen is dissolved in a short time and the duration of cooling is short. Further, even in a cooling agent in which a cryogen is brought into contact with a hydrate, it is difficult to maintain the cooling ability for a long time because water rapidly infiltrates when the cryogen starts to dissolve.

An object of the present invention is to maintain the cooling ability for a long time in a cooling agent which is cooled by mixing a cooling agent containing no water of crystallization and a cooling agent containing water of crystallization.

[0006]

The above object can be achieved by delaying one or both of the above-described two stages of cooling progress. Specifically, in the present invention, in a cooling agent in which a cryogen containing no water of crystallization and a cryogen containing water of crystallization are brought into contact with each other, at least one of a cryogen containing no water of crystal and a cryogen containing water of crystallization is porous. It is carried on the body. By supporting one or both of the cryogens on the porous body, the contact area between the cryogen not containing water of crystallization and the cryogen containing water of crystallization is reduced. Therefore, the transfer of the crystal water from the cryogen containing the crystal water to the cryogen not containing the crystal water is delayed, and the cooling ability is maintained for a long time. In addition, the cooling ability is maintained for a longer period of time because the porous body impedes the propagation of the substance that has become a liquid by melting the cryogen, that is, the infiltration of water.

Further, in the present invention, in a cooling agent in which a cryogen containing no water of crystallization and a cryogen containing water of crystallization are brought into contact with each other for cooling, the surface of the cryogen containing water of crystallization may be coated with a polymer substance. To maintain cooling capacity for a long time. By coating the surface of the cryogen containing water of crystallization, the rate of transfer of water of crystallization from the cryogen containing water of crystallization to the cryogen without water of crystallization is reduced, and the cooling capacity is maintained. Further, when the polymer substance has a property of increasing the viscosity of the electrolyte solution, the speed of the propagation of the substance in which the cryogen is dissolved and turned into a liquid state, that is, the infiltration of water is also reduced. As a result, the cooling capacity lasts for a longer time.

A cryogen that does not contain water of crystallization may be supported on a porous body, and the surface of the cryogen that contains water of crystallization may be coated with a polymer substance. In this case, maintenance of the cooling capacity for a long time is promoted.

A porous material carrying a cryogen is silica gel,
Alumina, cellulose, cellulose derivative, acrylic acid-methacrylic acid copolymer, hydroxylapatite, made from polyvinyl alcohol or polystyrene, the polymer substance for coating the surface of the cryogen containing water of crystallization, gum arabic, cellulose, cellulose derivative, Made from sodium polyacrylate, polyvinyl alcohol, polyvinyl butyral or polyvinyl pyrrolidone.

Ammonium nitrate, ammonium phosphate, ammonium dihydrogen phosphate, ammonium chloride, ammonium bromide, sodium phosphate or urea may be used alone or in combination as a freezing agent containing no water of crystallization. As a cryogen containing water of crystallization, sodium thiosulfate
Pentahydrate, disodium hydrogen phosphate dodecahydrate, sodium carbonate decahydrate, strontium sulfate decahydrate or strontium hydroxide octahydrate are used alone or in combination.

The cooling agent of the present invention is produced by allowing a solution in which a cryogen is dissolved to infiltrate a porous body and then drying the solution so that the cryogen is supported on the porous body. In addition, the surface of a cryogen containing water of crystallization is coated with a polymer substance by a spray coating method or a mechanochemical method.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment of Carrying Freezing Agent on Porous Body
The coolant of the embodiment will be described. As the freezing agent containing no water of crystallization, inorganic salts such as ammonium nitrate, ammonium phosphate, ammonium dihydrogen phosphate, ammonium chloride, ammonium bromide, sodium phosphate and urea are suitable. Depending on the purpose of use, other inorganic compounds or organic compounds other than urea may be used as long as they are substances that dissolve in water or absorb water to absorb heat.

The above compounds have different heats of dissolution, that is, endotherms, and the cooling temperature changes depending on which one is selected. An appropriate compound may be selected according to the desired cooling temperature. It is also possible to obtain an arbitrary cooling temperature by combining two or more. Furthermore, although the dissolution rate of each compound in water is large, they are different from each other, and by adjusting the ratio when two or more compounds are used in combination, the time during which a substantially constant cooling temperature continues can be adjusted. You can

The cryogen containing water of crystallization includes sodium thiosulfate pentahydrate, disodium hydrogen phosphate dodecahydrate, sodium carbonate decahydrate, strontium sulfate decahydrate or strontium hydroxide. Octahydrate is used. These hydrates differ in the binding force of water of crystallization, that is, the ability to release water of crystallization, and the duration of cooling can be adjusted to some extent by selecting the hydrate. A plurality of hydrates may be used in combination, and other hydrates may be used depending on the application as long as the bond strength of water of crystallization is not excessive.

As a material for the porous body, silica gel, alumina, cellulose, a cellulose derivative, an acrylic acid-methacrylic acid copolymer, hydroxylapatite, polyvinyl alcohol or polystyrene, which is easily available and easy to form a porous body, is used. To use.

The porous body is formed in a granular shape to facilitate the mixing of the coolant. The particle size is set in the range of 1 μm to 20 mm according to the application, and the pore size of the porous body is 0.001 to 5
0 μm, and the porosity of the porous body is preferably 50 to 99%.
The porous body can be loaded with a cryogen that does not contain water of crystallization or a cryogen that contains water of crystallization.
Further, both may be supported on separate porous bodies.

The cryogen is loaded on the porous body as follows. First, the cryogen is dissolved in water. When urea is used as a freezing agent containing no water of crystallization, it may be dissolved in alcohol. In order to increase the amount of cryogen carried on the porous body,
It is desirable to increase the concentration of the cryogen solution. The granular porous body is dipped in this freezing solution and left for a while. As a result, the cryogen solution infiltrates into the voids of the porous body. At this time, if a small amount of a surfactant is added to the solution, the infiltration rate of the solution into the voids of the porous body can be increased. In addition, it is also effective to apply air by stirring or ultrasonic waves to deaerate the air from the porous body.

After the freezing solution is sufficiently infiltrated, the porous body is taken out of the solution and dried. The amount of the cryogen carried may be increased by repeating the immersion in the cryogen solution and the drying. When the porous body is for supporting a cryogen containing water of crystallization, it is naturally dried at room temperature and atmospheric pressure. As a result, crystals of hydrate of the inorganic compound are deposited. On the other hand, when the porous body is for supporting a cryogen that does not contain water of crystallization, it is naturally dried at room temperature and atmospheric pressure to remove the attached water, and then heated or decompressed to be thoroughly dried. By heating or drying under reduced pressure, the crystal water is deprived from the crystals precipitated in a form containing the crystal water by natural drying. As a result, the crystal structure is broken into an amorphous state having a space inside, and a structure having a high affinity for water is obtained.

The cryogen used without being supported on the porous body is also pulverized into particles to facilitate mixing with the porous body carrying the cryogen. Cooling is started by bringing them into contact with each other. When used as a portable coolant, both should be separated and stored in a package that has a partition material that has relatively low mechanical strength and does not allow moisture to permeate, and the partition material should be ruptured and cooled immediately before use. To The same applies when both a cryogen that does not contain water of crystallization and a cryogen that contains water of crystallization are supported on the porous body.

As described above, in the cooling medium in which the cooling medium is supported on the porous body, the contact area between the cooling medium containing no water of crystallization and the cooling medium containing the water of crystallization is reduced, and the above two stages of cooling progress ( The step 1) can be delayed. Therefore, the duration of the cooling capacity becomes long. Further, when a cryogen that does not contain water of crystallization is supported on the porous body, the infiltration of the solution of the cryogen is hindered by the porous body, and the step (2) is also delayed. Therefore, the cooling capacity is maintained for a longer time.

The coolant of the second embodiment in which the surface of the cryogen containing water of crystallization is coated with a polymer substance will be described. The cryogen containing crystal water and the cryogen not containing crystal water are the same as those described in the above
What is shown in the embodiment of is used. As the polymer substance for coating the cryogen, one having a remarkable property of being dissolved or suspended in an electrolyte solution to increase its viscosity is particularly preferable. Specifically, gum arabic, cellulose, cellulose derivative, sodium polyacrylate, polyvinyl alcohol, polyvinyl butyral and polyvinyl pyrrolidone are used.

The cryogen containing water of crystallization is crushed into particles, and the surface thereof is coated with a polymer substance. The entire surface of the cryogen particles may be coated with the polymer substance, or only a part of the surface may be coated. The coating of the surface of the cryogen particles with the polymer substance is performed by two methods.

The first method is a spray coating method,
The polymer substance is dissolved or suspended in a solvent in advance, and this liquid is sprayed on the cryogen particles. In this method, a hydrophilic polymer is mainly used, but a hydrophobic polymer may be mixed. After spraying the liquid containing the polymer, the cryogen particles are dried to remove the solvent. This method is suitable for coating the entire surface of cryogen particles with a polymeric material.

The second method is a mechanochemical method, in which the cryogen particles and fine particles of a polymeric substance are collided and mixed in a processing container, and the physical energy is used to modify the cryogen particle surface and the cryogen particle surface. The polymer substance is attached to. The amount of polymer substances attached and the area covered with cryogen particles are
It is determined by the particle size ratio of the cryogen particles and the polymer particles and the amount of both particles mixed. This method is suitable for coating a part of the surface of cryogen particles. Freezing agent particle size is 1 μm ~
20 mm, and the coverage is preferably 2 to 99%.

The freezing agent which does not contain water of crystallization is also pulverized into granules, which is then mixed with the freezing agent particles containing water of crystallization which has been prepared by any of the above methods, and then cooled. At this time, the surface of the cryogen particles containing water of crystallization is covered with the polymer substance, so that the rate of crystallization water transfer to the cryogen without water of crystallization is reduced. In this way, the step (1) of the above two steps can be delayed.

Furthermore, in the present embodiment, since a polymer substance having a remarkable property of being dissolved or suspended in an electrolyte solution to increase its viscosity is used, when the cryogen is dissolved in crystal water to form an electrolyte solution, The solution viscosity becomes extremely high and the fluidity is greatly reduced. As a result, the infiltration rate of the freezing solution into the freezing particles is reduced, and the progress of the step (2) is also slowed down.

This cooling agent has a long-lasting cooling capacity due to the delay of both stages. The method of using it as a portable coolant is as described above.

Although the two embodiments of the present invention have been described above, they can be combined. That is, a cryogen that does not contain water of crystallization is supported on a porous body, and a cryogen that contains water of crystallization is coated with a polymer substance. In such a cooling agent, a decrease in the contact area due to the porous body and impeding the infiltration of the generated cryogen solution, a decrease in the movement of water of crystallization due to the high molecular weight substance and a decrease in the infiltration of the cryogen solution are combined, and the cooling ability is Is held for a longer time.

[0029]

EXAMPLES Examples of the cooling agent of the present invention will be described.
Foamed beads of methylcellulose having an average particle diameter of 3 mm and an average pore diameter of 20 μm were immersed in a saturated ammonium nitrate aqueous solution containing 0.1% of an alkylphenoxy polyethylene glycol type nonionic surfactant for 6 hours, then dried at room temperature and further at 70 ° C. It was dried for 12 hours. This operation of dipping and drying was carried out three times to obtain an ammonium nitrate-supporting porous body having a weight ratio of ammonium nitrate to methylcellulose of 4: 1. On the other hand, 5% polyvinylpyrrolidone (PV is used on the surface of strontium hydroxide octahydrate having an average particle diameter of 3 mm.
P) Spray coating an ethanol solution and drying at room temperature to obtain a PVP-coated strontium hydroxide / PVP / strontium hydroxide / octahydrate weight ratio of 1: 8.
Octahydrate was obtained.

The ammonium nitrate-supporting porous material, PVP-coated strontium hydroxide octahydrate, untreated ammonium nitrate particles and untreated strontium hydroxide octahydrate particles are shown in the following table. In combination with the above, four types of samples were prepared and the duration of the cooling capacity was determined. The duration of the cooling ability was measured as the time during which the sample was placed in a glass beaker and mixed well with a glass rod under conditions of room temperature of 30 ° C. and no wind, and the temperature of the glass beaker surface was kept at 10 ° C. or lower.

[0031]

[Table 1]

Samples 1 and 2 correspond to the first and second embodiments, respectively, and sample 3 is a combination of both. Sample 4 corresponds to a conventional coolant. As is clear from this table, the cooling agent of the present invention has a duration of cooling ability which is 2.5 times or more that of the conventional cooling agent.

[0033]

According to the coolant of the present invention, the cooling ability can be reliably maintained for a long time with a simple structure. Moreover, the duration of the cooling capacity can be adjusted depending on the setting of the pore size and the porosity of the porous body.

Even when using the coolant according to the second aspect, the cooling ability is surely maintained for a long time with a simple structure. Moreover, the duration of the cooling capacity can be adjusted by appropriately setting the amount of the polymer substance and the coating area.

When the cooling agent according to claim 3 is used, the duration of the cooling ability is further lengthened by both the effects of supporting the cooling agent by the porous body and coating the surface of the cooling agent by the polymer substance.

Since the readily available porous material or polymer substance is used in the cooling agents of claims 4 and 5, a long-lasting cooling agent can be easily realized.

According to the cooling agent of the sixth aspect, since the endothermic amounts of the respective compounds at the time of dissolution are different from each other, it is possible to realize the cooling temperature close to a desired temperature by appropriately selecting the compounds. Further, if used in combination, it becomes easier to achieve a desired cooling temperature. Further, since the dissolution rates of these compounds in water are different from each other, by using them in combination, it is possible to cool at a stable temperature for a long time.

According to the cooling agent of the seventh aspect, since the hydrated water releasing ability of each hydrate is different from each other, the duration of the cooling ability can be adjusted by selecting the hydrate.

The method for producing a coolant according to claim 8 is extremely simple, and a long-lasting coolant can be easily produced without using a complicated device.

The method for producing a coolant according to claim 9 is also simple,
Long lasting coolants are easily manufactured.

Claims (9)

[Claims] 1. A cooling agent in which a cryogen containing no water of crystallization and a cryogen containing water of crystallization are brought into contact with each other to cool, and at least one of a cryogen containing no water of crystallization and a cryogen containing water of crystallization is supported on a porous body. A cooling agent characterized by having a sustained cooling capacity. 2. A cooling agent in which a cryogen that does not contain water of crystallization and a cryogen that contains water of crystallization are brought into contact with each other to cool them, and the cooling ability is sustained by coating the surface of the cryogen that contains water of crystallization with a polymer substance. Coolant characterized by the following. 3. A cooling agent in which a cryogen that does not contain water of crystallization and a cryogen that contains water of crystallization are brought into contact with each other for cooling, and a cryogen that does not contain water of crystallization is supported on a porous body, and the surface of the cryogen that contains water of crystallization is A cooling agent characterized in that the cooling ability is sustained by coating with a polymer substance. 4. The porous body is made of silica gel, alumina, cellulose, a cellulose derivative, an acrylic acid-methacrylic acid copolymer, hydroxylapatite, polyvinyl alcohol or polystyrene. Coolant according to. 5. The cooling according to claim 2, wherein the polymer substance comprises gum arabic, cellulose, a cellulose derivative, sodium polyacrylate, polyvinyl alcohol, polyvinyl butyral or polyvinyl pyrrolidone. Agent. 6. The freezing agent containing no water of crystallization comprises one of ammonium nitrate, ammonium phosphate, ammonium dihydrogen phosphate, ammonium chloride, ammonium bromide, sodium phosphate or urea, or a combination of two or more thereof. The coolant according to any one of claims 1 to 5, which is characterized. 7. The cryogen containing water of crystallization is sodium thiosulfate pentahydrate, disodium hydrogen phosphate dodecahydrate, sodium carbonate decahydrate, strontium sulfate decahydrate or hydroxide. The coolant according to any one of claims 1 to 5, which comprises one of strontium octahydrate and a combination of two or more thereof. 8. The method for producing a cooling agent according to claim 1 or 3, wherein a solution in which a cryogen is dissolved is infiltrated into the porous body and then dried to support the cryogen on the porous body. Method. 9. The method for producing a coolant according to claim 2 or 3, wherein the surface of the cryogen containing water of crystallization is coated with a polymer substance by a spray coating method or a mechanochemical method.