JP2005113005A - Constant temperature refrigerant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly convenient constant temperature refrigerant, not requiring pre-use refrigeration in a refrigerating environment, with thermal circulation cycle efficiency improved by micronizing crystals. <P>SOLUTION: Appropriate amounts of sodium sulphate, a smectite such as montmorillonite clay, and water are mixed for the preparation of a properly thixotropic suspension wherein a saturated decahydrate solution is dispersed. A desired level of elasticity or fluidity may be achieved conbinedly when the constant temperature refrigerant constituting elements are mixed at a weight ratio of 20:1:20, that is, when a smectite of approximately 5 wt.% is added to sodium sulfate (=water), for manufacturing a high-efficiency constant-temperature refrigerant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a constant temperature refrigerant material that maintains a constant cooling temperature for a long time by reversibly changing the amount of heat from an external heating element or the like without refrigerating the refrigerant material in advance.

Conventionally, a cold-retaining agent using a water-absorbing resin (hydro-gel polymer) called a polymer polymer or a water-absorbing polymer gel as a refrigerant material for an external heat source is well known.
In addition, there are isothermal refrigerants using sodium phosphate or sodium sulfate, which is a refrigerant material that recrystallizes by refrigerating and crystallizing the refrigerant substance by absorbing heat from the outside and generating a heat recirculation to dissipate heat on the surface layer (for example, patents) Reference 1 and 2).
Japanese Utility Model Publication No. 58-196667 Japanese Utility Model Publication No. 6-52815

However, the gel-like refrigerant material using the former water-absorbent resin generally utilizes the property of absorbing water of several hundred to several thousand times the weight of the water-absorbent resin and holding it in a gel state. In order to use the heat capacity and latent heat of the retained water for cooling, it is necessary to cool in advance in a freezing environment such as ice, dry ice, and a refrigerator. In addition, depending on the heat capacity of the water held by itself, if it is desired to use it as a refrigerant for a long time, it must be cooled to a refrigerated state, and the refrigerant material itself is in an ice temperature state. When it is not desired to lower the temperature extremely due to problems such as cell destruction or when it is used directly on the human body, it is necessary to interpose an appropriate temperature adjusting material between the refrigerant material and the object to be cooled.

Also, the constant temperature refrigerant material such as the latter has low cooling efficiency because it is difficult to melt and difficult to be uniformly distributed in the refrigerant material due to the sharp crystallization and large crystal size at the time of heat recrystallization of sodium sulfate. In particular, there is a problem that the thermal circulation cycle does not work skillfully due to poor fluidity, and it is difficult to make practical application. In particular, it is a hindrance to downsizing and narrow structure, and a crystal shape such as sharp crystallization requires a durable strength for the container material and bag material, which also hinders heat absorption and heat dissipation.

Therefore, the present invention has been made in view of such a conventional problem, and is a constant temperature refrigerant material that does not need to be cooled in a refrigeration environment in advance, and has a convenience in which the thermal circulation cycle is made efficient by miniaturization of crystals. It aims at enabling it to provide the refrigerant | coolant material excellent in property.

In order to solve the above problems, the present invention according to claim 1 is based on sodium sulfate as an endothermic medium and smectite, which is a kind of swellable clay mineral, as a main component, and adding and mixing an appropriate amount of water. Thus, the crystal of sodium sulfate is refined and has thixotropic properties (thixotropic properties).

Further, the present invention according to claim 2 is characterized in that sodium sulfate which is a component material in the constant temperature refrigerant material, smectite which is a kind of swellable clay mineral, and water have a weight mixing ratio of about 20: 1: 20. It is characterized by that.

According to this invention, the refined sodium sulfate crystals dispersed in the constant temperature refrigerant absorb a large amount of heat released from the external heating element when the crystals are dissolved, and an efficient thermal circulation cycle is formed in which recrystallization occurs after heat release. Is done. Furthermore, when the sodium sulfate is recrystallized after heat release, the mixed smectite suspension works in a direction to prevent the crystal from becoming large. Refrigerant material can be supplied, and convenience and applicability can be improved.

Sodium sulfate (NaSO ₄ .nH ₂ O) as an endothermic medium in the present invention is used as Na ₂ SO ₄ .10H ₂ O by adding water. This Na ₂ SO ₄ .10H ₂ O is called decahydrate or Glauber Salt, and has the property of forming a supersaturated solution, and repeats the following reversible transformation at a temperature of about 32 ° C.
(Chemical formula 1)
Na ₂ SO ₄・ 10H ₂ O ⇔ Na ₂ SO ₄ + 10H ₂ O
Specifically, decahydrate crystals precipitate in the solution at a temperature of 32.38 ° C. or lower, dissolve at the temperature or higher, and decompose into anhydrous sodium sulfate and water. What should be noted is the property of absorbing a large amount of heat of fusion up to 58.3 Kcal / Kg during this dissolution, and this constant temperature refrigerant utilizes this endothermic action.

Smectite, the other component of this constant temperature refrigerant, is a kind of swelling clay mineral with a lamellar octahedral crystal structure, such as Montmorilonite, Beidelite, Nontronite Is known and has an active surface area of several hundred m ² / g and at the same time has a swelling property to absorb and retain water several times its own weight due to its high polarity. By mixing these smectites such as sodium sulfate, montmorillonite clay, and water in an appropriate ratio, a suspension having an appropriate thixotropic property (thixotropic property) can be obtained by allowing the smectite to absorb water and swell and develop colloidal properties. A saturated solution of decahydrate is diffused. In addition, at the same time, it is possible to provide flexibility and fluidity that are effective when encapsulated and used in a soft container or a narrow container.

At this time, the mixing ratio, which is a component of the constant temperature refrigerant material, varies depending on the application form of the refrigerant material, but it is effective that the weight ratio of sodium sulfate: smectite: water is about 20: 1: 20, That is, it is preferable to adjust and blend smectite with sodium sulfate (= water) at 2 to 5% by weight.

Hereinafter, the cooling principle of the present invention will be described with reference to FIG. 1 and a specific embodiment with reference to FIGS. As shown schematically in FIG. 1, the constant temperature refrigerant material 1 (container and container not shown) is about 32 ° C. or less in a suspension 3 having an appropriate thixotropy (Na ₂ SO _4. 10H ₂ O) 2 is dispersed and precipitated in a microcrystalline state, but when the heat from an external heating element (not shown) is absorbed, the crystals of the decahydrate absorb as melting heat and dissolve, By repeating the endothermic-heat dissipating heat cycle in which heat is released and recrystallized in the surface layer in the form of reversible transformation of sodium sulfate, and because the heat of fusion of the decahydrate crystals is very large, it takes about 32 hours. Keep the temperature around ℃. Further, when the sodium sulfate is recrystallized, the appropriate thixotropy of the mixed smectite suspension and the fluidity due to the thermal circulation act in the direction of hindering crystal enlargement due to contact bonding between the crystals.

FIG. 2 shows an example of a mat-like application product on the premise that it is used in direct contact with the human body or animal. The periphery 6 and part 7 of the container composed of a soft resin sheet (PVC, EVA, etc.) 5 are welded, and the constant temperature refrigerant material of the present invention is sealed inside. Increasing the number of partial welds in the periphery 6 and part 7 is intended to reduce the thickness of the mat, but thermal recirculation is not hindered by miniaturization of the decahydrate crystals in the refrigerant material, In order to give strength to the sharp protrusions of recrystallization, the soft resin sheet needs to be thicker than necessary, and it is not necessary to reduce the heat absorption and radiation efficiency. Moreover, the flexibility of the mat becomes good due to the appropriate thixotropy of the refrigerant material. Therefore, it has a wide range of applications, such as ice pack substitutes and cold compresses for medical use, and bedding, transportation, and equipment cooling, and the container is not limited to the above-mentioned bag-like soft resin. As long as conduction and water tightness are taken into consideration, the shape and material are not limited.

FIG. 3 is a schematic graph showing the results of measuring the temperature change with time using a thermistor thermometer when the mat-like application product (FIG. 2) is used on the human head assuming a medical ice bag or bedding. In the graph, 8 (chain line) indicates the head contact part temperature, and 9 (solid line) indicates the refrigerant temperature. As can be seen from this graph, the head temperature starts to be absorbed from the room temperature (constant temperature) state of about 26 ° C. at the start of use, and the head is cooled. Water salt) absorbs the amount of heat and spends it for dissolving the crystals, and at the same time, the refrigerant material keeps a cooling temperature that is not irritating to the human body at about 32 ° C. for a long time by internal heat circulation.

It is a schematic diagram explaining the cooling principle of the constant temperature refrigerant material of the present invention. It is a sheet-like applied product enclosing the constant temperature refrigerant material of the present invention. It is a temperature characteristic graph at the time of using directly on a human body.

Explanation of symbols

1 Constant Temperature Refrigerant Material 2 Sodium Sulfate (Decahydrate) Crystal 3 Smectite Suspension 4 Constant Temperature Refrigerant Material Filling Portion 5 Sheet Surface 6 Body Surrounding Welding Portion 7 Central Welding Portion 8 Head Contact Site Temperature 9 Refrigerant Temperature

Claims (2)

Sodium sulfate as an endothermic medium and smectite, a kind of swellable clay mineral, are the main components. By adding and mixing an appropriate amount of water, the crystals of sodium sulfate are refined and thixotropic. A constant temperature refrigerant material. 2. The isothermal refrigerant material according to claim 1, wherein sodium sulfate as a constituent material, smectite as a kind of swellable clay mineral, and water have a weight mixing ratio of about 20: 1: 20. Constant temperature refrigerant material.