JP2002371269A - Mixed low-temperature insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a combination of salts which give a useful cold storage agent when mixed. SOLUTION: The cold storage agent comprises a combination of univalent or bivalent salts composed of the same anion and different in counter cations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold insulator and a cold storage agent. Here, the agent refers to an aqueous solution containing the component, and the refrigerating material refers to a refrigerating agent filled in a container.

[0002]

BACKGROUND OF THE INVENTION For mixed cryogens, NH ₄ Cl and K
NO ₃ , NaNO ₃ and NH ₄ NO ₃ , KNO ₃ and NH ₄
SCN and the like are known. However, there are no reports on cold storage agents. In addition, a cold storage agent that provides a low temperature of -35 ° C. or less as an alternative to dry ice has not been found.

[0003]

The present invention finds a combination of salts which, when used as an aqueous solution and frozen, provides a useful regenerator. Also, a regenerator that maintains a low temperature of -35 ° C or less is found.

[0004]

The present inventors have found that an aqueous solution obtained by mixing salts having the same anion but different cations can be a useful regenerator.
Among the anions, chloride, sulfate and nitrate ions have an effect. Monovalent salts and divalent salts are classified according to cations. Sodium ions, potassium ions, and ammonium ions are useful as cations of monovalent salts, and magnesium ions and calcium ions are practically used as divalent cations. Useful.

[0005] In the mixture, the anions are the same, but the corresponding cations must be monovalent and monovalent, divalent and divalent, and so on. For example, a combination of monovalent sodium ions and divalent magnesium ions as cations is not used for chloride ions (monovalent).

In the present invention, for the monovalent salt, the anion is most preferably a chloride ion (Cl ⁻ ), and the cations are a sodium ion (Na ⁻ ), a potassium ion (K ⁻ ), and an ammonium ion (NH _4). ^Of- ), a mixture of two or three is preferred. Regarding Cl ⁻ , as a result of various experiments, the melting temperature was significantly lowered,
This is because a phenomenon such as an increase in retention time was observed in chloride ions. The cations of the divalent salt are magnesium ion (Mg ²⁺ ) and calcium ion (Ca ²⁺ )
And the corresponding anion is preferably chloride ion, sulfate ion and nitrate ion.

Therefore, a preferred specific combination of the present invention is a monovalent salt comprising NaCl and KCl, NaCl and NH ₄
Cl, KCl and NH ₄ Cl, NaCl, KCl and NH ₄
Cl. Among the divalent salts, MgCl ₂ and CaCl ₂ are used as chlorides, and Na ₂ SO ₄ and MgSO ₄ are used as sulfates, and K ₂ SO ₄ and MgSO ₄ are used as sulfates.
_And nitrates include Na ₂ NO ₃ and MgN
O ₃ , K ₂ NO ₃ and MgNO ₃ , Na ₂ NO ₃ and CaN
There are O ₃ , K ₂ NO ₃ and CaNO ₃ . Three types can also be combined.

[0008] Among the divalent salts, the combination of calcium ion and magnesium ion as the anion is chloride ion and the cation is lower in melting point than the single one in the experiment.
The most favorable result was obtained in terms of increasing the retention time. Furthermore, the temperature is the low temperature required for dry ice replacement.
37 ° C. (when calcium chloride is added to the main component of magnesium chloride) and −45 ° C. (when magnesium chloride is added to the main component of calcium chloride).

According to an embodiment of the present invention, for example, NaC
1 or KCl as a single regenerator with NH ₄ Cl １ ／ to 1/1 /
Add 10 volumes, preferably 1/3 to 1/5 volume. Conversely, NH
_{To the 4} Cl single regenerator, add Nacl or Kcl, preferably 1/3 to 1/5. The main component NaCl
Alternatively, KCl is reduced by 1/3 to 1/5, and NH ₄ Cl is reduced accordingly.
In addition, favorable results are obtained even if the total amount is substantially the same. The concept is the same for the divalent salts MgCl ₂ and CaCl ₂ . For example, a MgCl ₂ in 15 wt% aqueous solution, adding CaCl ₂ 5 to 7 wt%. Alternatively, 5% by weight of CaCl ₂ , which is a quarter amount, is added to a 20% by weight solution of MgCl ₂ . The main component concentration is 5 to 30% by weight, preferably 10 to 20% by weight. The aqueous solution thus obtained is placed in a container made of polyethylene or the like, frozen and used as a cold insulator. A measure of the concentration of a single regenerator is to measure the retention time and select a concentration that is not too short.

[0010]

According to the present invention, the main component of MgCl ₂ is CaC
The l ₂ were mixed, cool storage agent obtained by dissolving in water, the holding temperature is as low as -36 ° C., and the holding time is longer than MgCl ₂ single piece. The main component is CaCl ₂ and MgCl _{2
When 2} is mixed, -45 ° C is obtained. A low-temperature cold insulator containing these in a container can be a dry ice substitute as never before. In addition, a mixture obtained by mixing NH ₄ Cl with NaCl main component (−20 ° C.) and dissolving it in water has a low melting point of −25 ° C. and a long retention time when frozen. (See FIG. 1.) Thus, a regenerator superior to that of the main component alone can be obtained.

[0011]

Example 1 A single cold storage agent of a 23% aqueous solution of sodium chloride and an aqueous solution composed of 17% of sodium chloride and 5% of ammonium chloride were respectively frozen, and their melting temperatures were compared.
The former was −20 ° C., and the temperature of the mixed cooling agent was −25 ° C. The retention times were the same.

[0012]

Example 2 A single regenerator of a 20% aqueous solution of potassium chloride and an aqueous solution consisting of 15% of potassium chloride and 5% of ammonium chloride were respectively frozen, and their melting temperatures were compared. The former was -10.5 ° C, and the mixed regenerator was -17 ° C. Retention times were comparable.

[0013]

Example 3 A single regenerator with 20% ammonium chloride,
A regenerator containing a mixture of 20% ammonium chloride and 5% potassium chloride was placed in a polyethylene container having a thickness of 1 mm and then frozen to compare the surface temperatures. The former is −16 ° C., the latter is −
Although the temperature was 17.5 ° C., the retention time of the latter was 1.15 times longer.

[0014]

Embodiment 4 A polyethylene container having a thickness of 1 mm and a volume of 550 ml was filled and frozen, and one of them was placed in styrene foam having a thickness of 30 × 21 × 12 cm and a thickness of 2 cm. Magnesium chloride 1
5% shows a melting temperature of −31 ° C., whereas when calcium chloride is added thereto, the melting point is slightly lowered when the added amount is 2.5%, and markedly lowered when 5% is added. ing. In addition, the melting point is also lowered when magnesium chloride is set to 20%.

[0015]

Example 5 A single solution of potassium chloride 10% is -11 ° C.
However, the temperature of the regenerator added so as to be 3% of ammonium chloride was −13 ° C.

[0016]

EXAMPLE 6 A single solution of 15 to 17% by weight of calcium chloride exhibited -44 ° C, whereas a mixture of 15% by weight of calcium chloride and 5% by weight of magnesium chloride was -47.5 ° C.
showed that.

[Brief description of the drawings]

FIG. 1 shows a comparison of the surface temperatures when two cold insulators are used in Example 4. It can be seen that the temperature of the chloride-mixed cold insulator is lower than that of the single material, and there is no difference in the change with time. ▲ −− ▲ Magnesium chloride 15%, Calcium chloride 5% ◆ −− ◆ Magnesium chloride 15% △ −− △ Sodium chloride 17%, Ammonium chloride 5% ◇ −− ◇ Sodium chloride 23%

Claims (5)

[Claims] 1. A regenerator comprising a combination of water-soluble monovalent or divalent salts in which the anions are the same and the corresponding cations are different. 2. The regenerator according to claim 1, wherein the cation of the monovalent salt is a combination of two or three of sodium ion, potassium ion and ammonium ion, and the anion is chloride ion. 3. The regenerator according to claim 1, wherein the cations of the divalent salt are magnesium ions and calcium ions, and the anions are chloride ions, sulfate ions or nitrate ions. 4. The method according to claim 3, wherein the anion is a chloride ion.
The cold storage agent as described. 5. A cold insulating material in which a container is filled with the cold storage agent according to claim 1.