JP2007161894A - Cold insulator and cold-insulating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold insulator which is used for maintaining coolness of a cold-insulated target article whose optimum temperature is within the range of from above 0°C to below 10°C and is characterized by (1) a phase change temperature (melting point) corresponding to an optimum temperature or temperature range for the cold-insulated target article, (2) a large latent heat, (3) a large specific heat in a liquid state, (4) the lack of phase separation or performance deterioration after repeating a solidification-melting cycle, (5) a minimum change in the melting temperature and (6) incombustibility, and to provide a cold-insulating material composed of a container or a bag filled with the cold insulator. <P>SOLUTION: The cold insulator comprises tri-n-butylalkylammonium salt and water. The cold insulator comprises tri-n-butyl-n-pentylammonium bromide and water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a cold insulation agent used for storage, transportation, cooling and the like at low temperatures in the fields of foodstuffs, processed food products, medicine, and the like, and a cold insulation material filled with the cold insulation agent in a container.
In the present invention, a substance having a cold-retaining (or cooling) function is referred to as a “cold-retaining agent”, and a substance that is filled in a container, a bag, or the like and used for cold-retention is referred to as a “cold-retaining material”.

Fresh fish and shellfish, fresh vegetables, fruits, meat, other fresh foods, processed foods, dairy products, flowers, films, medicines, medical specimens etc. are transported under low temperature control or temporarily in a place without cold storage facilities In order to maintain these freshness, taste, quality, performance, and utility when stored at a low temperature, a cold insulating material is used.
The cold insulator is also used for cooling such as local cooling of the human body.

  Various compositions that utilize latent heat associated with phase change have been employed as a cryogen. Since the latent heat cooling agent that has been cooled and solidified in advance has latent heat, it is melted at a certain melting temperature, so that the object to be cooled can be kept at a low temperature.

The following are listed as properties required for the refrigerant.
(1) Phase change temperature (melting point) corresponding to an appropriate temperature or temperature range (hereinafter referred to as “appropriate cooling temperature”) desired for an article to be kept cold (hereinafter referred to as “cooled object”). It is desirable that the melting temperature (corresponding to the melting point) or the melting temperature range that is maintained until the latent heat that has been melted and stored is released corresponds to the appropriate cooling temperature of the object to be cooled.
(2) Large amount of latent heat If the amount of latent heat is large, it takes a long time for the solidified cryogen to melt and release the stored latent heat, and the time for maintaining the melting temperature is long. This is preferable because it takes a long time.

(3) The specific heat of the cryogen in the liquid state is large. After the solidified cryogen is melted and the release of latent heat is completed, the temperature of the cryogen in the liquid state rises, but the specific heat in the liquid state of the cryogen is large. And it takes a long time for the temperature of the cryogen to reach the ambient temperature, and the object to be cooled can be held for a long time at a temperature closer to the appropriate cooling temperature, and the freshness, quality, performance, utility, etc. of the object to be cooled Can be delayed.
(4) Phase separation does not occur due to repeated solidification and melting, and the performance does not deteriorate. The cryogen must be able to withstand repeated use of solidification and melting. Therefore, it is necessary that the phase separation phenomenon that does not partially melt at the time of melting and remain as a solid phase or the heat storage performance deteriorate due to repeated solidification and melting that repeatedly accumulate and release latent heat.
If necessary, (1) the melting point according to the appropriate cooling temperature, (2) large latent heat, (3) large specific heat in the liquid state, and (4) the ability to withstand repeated use is used as a cryogen. It can be said that it is an important property to be possessed by the latent heat cryogen.

In addition, (5) when the latent heat cooling agent that has been cooled and solidified in advance is melted, the melting temperature does not change with the progress of melting, or the melting temperature changes as little as possible. More preferably, the object to be cooled can be kept at a constant temperature and a low temperature.
Furthermore, (6) nonflammability is also required.

Further, in the field of air conditioning, there are materials that mainly use ice, paraffin, inorganic hydrates, organic hydrates, etc. as regenerators using latent heat, and it is conceivable to use these as latent heat coolers.
Trimethylolethane (TME) hydrate is known as a latent heat regenerator mainly composed of organic hydrates, and studies are being made centering on TME-water-urea ternary systems (patents). Reference 1).
Moreover, there exists a hydrate of a quaternary ammonium compound as another example of the latent heat cool storage agent which uses an organic hydrate as a main ingredient (refer patent document 2).
JP 2000-256659 A Japanese Patent No. 3641362

  Many of the objects to be kept cool mainly for food such as fresh fish, fresh food, and dairy products have an appropriate cooling temperature in the range of 0 to 10 ° C. As described above, the latent heat regenerator having a melting point in this temperature range includes, for example, ice, paraffin, inorganic hydrate, organic hydrate and the like as a main ingredient.

  Ice is generally used for cold storage during the distribution of fresh fish, but since it is kept cold at 0 ° C, it has the same high commercial value as live fish and is called "living" from just after death to complete rigidity. There is a problem that it cannot be kept in the range of 5 to 10 ° C. suitable for maintaining the temperature, and cannot be used as a cryogen at a temperature higher than 0 ° C. in order to distribute “live” fresh fish with high commercial value.

  Since paraffin is flammable, it is problematic for use as a cryogen. Inorganic hydrates do not satisfy the above condition (4) that phase separation does not occur or performance deteriorates due to repeated solidification and melting, and are unsuitable as a cryogen. For example, a cold storage agent in which ammonium chloride or the like is added as a melting point adjusting agent to sodium sulfate decahydrate is known as an inorganic salt hydrate cold storage agent having a melting point of 9 ° C. However, if solidification and melting are repeated, it tends to cause phase separation. is there.

  The heat storage material composition comprising the clathrate hydrate of Patent Document 1 as a main ingredient is said not to cause phase separation even if the solidification and melting are repeated 100 times, but the melting point is higher than 10 ° C, so 0 to 10 ° C. Therefore, it is not suitable for the cooling of “living” fresh fish that is required to be kept in the range of 5 to 10 ° C.

In addition, among the latent heat regenerators mainly composed of clathrate hydrates of quaternary ammonium compounds of Patent Document 2, tetra nbutylammonium bromide (TBAB) will be described as an example. The melting point (harmonic melting point) of the TBAB aqueous solution of about% by weight is about 12 ° C., and heat storage and heat dissipation are repeated without phase separation at this temperature. However, although the condition of the cryogen that can withstand repeated use is satisfied, it cannot be used as a cryogen for an object to be cooled having an appropriate cooling temperature in the range of 0 to 10 ° C. (The harmonic melting point will be described later.)
As described above, the latent heat coolers that have been put to practical use or proposed so far have their respective problems.

  The present invention has been made to solve these problems, and is used for keeping a cold object having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C., and satisfies the above (1) to (6). An object of the present invention is to provide a cold insulation material that is configured by filling a container or a bag with the cold insulation agent.

(1) The cryogen according to the present invention is characterized by containing a tri-n-butylalkylammonium salt and water.

An aqueous solution containing a tri-n-butylalkylammonium salt and water is cooled to produce a tri-n-butylalkylammonium salt hydrate, which can be used as a cold insulation material mainly composed of the hydrate.
Examples of the alkyl include n-pentyl, isopentyl, npropyl, isopropyl, ethyl, methyl, nhexyl, isohexyl, nheptyl, isoheptyl, isobutyl and the like other than nbutyl.
As ammonium salts, ammonium bromide, ammonium chloride, ammonium fluoride, ammonium nitrate, ammonium nitrite, ammonium chlorate, ammonium perchlorate, ammonium bromate, ammonium iodate, carbonic acid Ammonium salts, ammonium phosphate salts, ammonium tungstate salts, ammonium sulfate salts, ammonium hydroxide salts, ammonium carboxylates, ammonium dicarboxylates, ammonium sulfonates, ammonium disulfonates and the like can be mentioned.

(2) Further, it is characterized by containing tri-n-butyl-n-pentylammonium bromide and water.

(3) Further, the main component is tri-n-butyl-n-pentylammonium bromide hydrate.

  Tri-n-butyl-n-pentylammonium bromide forms clathrate hydrate, the concentration giving a harmonic melting point is 34% by weight and the harmonic melting point is approximately 6 ° C. The amount of latent heat at this harmonic melting point is 193 J / g, which has a high amount of latent heat. The specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K. Further, even if solidification and melting are repeated, there is no decrease in phase separation or heat storage performance. Since it has such a characteristic, it is suitable as a cold-retaining agent for a cold object having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C.

(4) Further, it is characterized by containing tri-n-butyl-n-pentylammonium chloride and water.

(5) Further, it is characterized by containing tri-n-butyl-n-pentylammonium chloride hydrate as a main component.

  Tri-n-butyl-n-pentylammonium chloride forms a clathrate hydrate, the concentration giving the harmonic melting point is 33% by weight, the harmonic melting point is approximately 9 ° C., and the latent heat at the harmonic melting point is 195 J / g, It has a high amount of latent heat. The specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K. Further, even if solidification and melting are repeated, there is no decrease in phase separation or heat storage performance. Since it has such a characteristic, it is suitable as a cold-retaining agent for a cold object having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C.

(6) Further, it is characterized by containing tri-n-butylalkylammonium salt, tetraalkylammonium salt and water.

  When the aqueous solution of tri-n-butylalkylammonium salt and tetraalkylammonium salt is cooled, tri-n-butylalkylammonium salt hydrate and tetraalkylammonium salt hydrate are produced. By producing two hydrates having different melting points, thermal characteristics different from those of a single hydrate can be obtained.

Examples of the alkyl in the tetraalkylammonium salt include n-butyl, isobutyl, npentyl, isopentyl, npropyl, isopropyl, ethyl, methyl, nhexyl, isohexyl, nheptyl, isoheptyl, isobutyl and the like. As ammonium salts, ammonium bromide, ammonium chloride, ammonium fluoride, ammonium nitrate, ammonium nitrite, ammonium chlorate, ammonium perchlorate, ammonium bromate, ammonium iodate, carbonic acid Ammonium salt, ammonium phosphate salt, ammonium tungstate salt, ammonium sulfate salt, ammonium hydroxide salt, carboxylic acid ammonium salt, dicarboxylic acid ammonium salt, sulfonic acid ammonium salt, disulfonic acid ammonium salt Umm salts and the like.
Specific examples of the tetraalkylammonium salt include, for example, tetra nbutylammonium bromide.

(7) Further, it is characterized by containing tri-n-butyl-n-pentylammonium bromide, tetra-n-butylammonium bromide and water.

(8) Further, it is characterized by comprising tri-n-butyl-n-pentylammonium bromide hydrate and tetra-n-butylammonium bromide hydrate as main components.

Produces a hydrate with a different melting point from tri-n-butyl-n-pentylammonium bromide hydrate, for example, a tetraalkylammonium salt such as tetra-n-butylammonium bromide and tri-n-butyl-n-pentylammonium bromide mixed with water By doing so, the temperature at which the hydrate is formed when the mixed aqueous solution is cooled (mixture melting point) can be made lower or higher than the melting point of tri-n-butyl-n-pentylammonium bromide hydrate alone.
Therefore, the melting point of the mixture can be adjusted to a desired range by adjusting the blending composition of tri-n-butyl-n-pentylammonium bromide and the tetraalkylammonium salt. For this reason, it is possible to provide a cold insulating material having a melting temperature that matches an appropriate cooling temperature desired for the object to be cooled.
It has been confirmed that the total latent heat amount of the mixture is substantially equal to the sum of the latent heat amounts of tri-n-butyl-n-pentylammonium bromide hydrate and tetraalkylammonium salt hydrate multiplied by the blending composition ratio.

(9) Further, it is characterized by containing tri-n-butyl-n-pentylammonium chloride, tetra-n-butylammonium bromide and water.

(10) It is also characterized by comprising tri-n-butyl-n-pentylammonium chloride hydrate and tetra-n-butylammonium bromide hydrate as main components.

(11) The cold insulating material according to the present invention is characterized by filling a container or a bag with the cold insulating agent according to any one of the above (1) to (10).

As the container or bag body filled with the cold insulation agent, a known one used as a container or bag body of a cold insulation material can be used. For example, bags or containers (bags / packs that contain jelly drinks or shampoos for refills), plastic molding, made of a flexible material sheet made of synthetic resin film laminated with metal foil (such as aluminum foil) Examples include containers.
A cold insulation material is prepared by filling a plastic container or bag body with a cold insulation agent, and the cold insulation material is cooled in advance, and is stored in a cold insulation container together with an object to be cooled and distributed and stored.

  The cooling agent of the present invention contains tri-n-butylalkylammonium salt and water, has a melting point corresponding to an appropriate cooling temperature of 0 ° C. to 10 ° C., has a large latent heat, Since it has a characteristic that it has a large specific heat in a liquid state and can withstand repeated use, it is suitable as a cryogen for a cold object having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C.

  The characteristic of the Example of this invention cooler is shown in the following Table 1, and each Example is demonstrated based on Table 1. FIG.

1) Example 1: Tri-n-butyl-n-pentylammonium bromide (TBPAB) harmonic concentration hydrate DSC (differential scanning calorimeter) measurement was carried out at different concentrations for tri-n-butyl-n-pentylammonium bromide aqueous solution. The melting point and latent heat of the hydrate were measured. As a result, it was confirmed that the melting point became maximum at a weight concentration of 34% in the phase diagram with the melting point temperature on the vertical axis and the concentration on the horizontal axis, and the concentration giving the harmonic melting point (called the harmonic concentration) was 34%. The definition of the harmonic melting point will be described later.

The harmonic melting point was 6 ° C., the amount of latent heat was 193 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.7 J / g · K.
Thus, the latent heat amount at the harmonic melting point of tri-n-butyl-n-pentylammonium bromide hydrate is 193 J / g, and since it has a large latent heat amount, the solidified hydrate melts and releases the stored heat. It takes a long time to finish. Therefore, since the time that is maintained at the melting temperature is long, the time that is maintained at the appropriate cooling temperature is excellent when used as a cryogen.

In addition, the specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K, and since the specific heat is large, it is difficult to raise the temperature, and the time until the temperature of the aqueous solution reaches the ambient temperature becomes long. Therefore, it is preferable that the object to be cooled can be kept at a temperature close to the appropriate cooling temperature for a long time when used as a cryogen.
It was also confirmed that there was no decrease in phase separation or heat storage performance even after solidification and melting 1000 times.
Furthermore, tri-n-butyl-n-pentylammonium bromide hydrate is preferred without toxicity.

  As described above, since tri-n-butyl-n-pentylammonium bromide hydrate has such characteristics, it is used as a cold-retaining agent for an object to be cooled having an appropriate cooling temperature in a range higher than 0 ° C. and lower than 10 ° C. Is preferred.

The harmonic melting point means that the composition before and after the phase change from an aqueous solution (liquid phase) to a hydrate (solid phase) does not change when an aqueous solution of a compound that forms a hydrate is cooled to produce a hydrate. The temperature of the case (eg, producing a hydrate with the same concentration as the compound concentration that produces the hydrate in the original aqueous solution). In the state diagram in which the vertical axis represents the melting point temperature and the horizontal axis represents the concentration, the maximum point is the harmonic melting point.
In the present specification, a concentration that provides a harmonic melting point is referred to as a harmonic concentration.
When an aqueous solution with a harmonic concentration is cooled, hydrates begin to form at the harmonic melting point, and the temperature is constant at this melting temperature until all aqueous solutions are hydrated. Similarly, melting occurs at this constant melting temperature. If the hydrate has a harmonic concentration, there is no change in the melting temperature at the time of melting, and the melting temperature is constant at the harmonic melting point.
When the concentration is lower or higher than the harmonic concentration, the melting temperature becomes lower than the harmonic melting point.
When an aqueous solution having a concentration lower than the harmonic concentration is cooled to melt the solidified hydrate, melting begins at a temperature lower than the harmonic melting point, and the melting temperature gradually increases as the melting proceeds.

2) Example 2: Tri-n-butyl-n-pentylammonium bromide (TBPAB) less than harmonious hydrate For hydrates less than harmonious, the melting temperature changes as the melting progresses, By setting the concentration to less than the harmonic concentration, the melting temperature region can be made a region having a temperature lower than the harmonic melting point, so that the object to be cooled can be used as a cold insulating agent that can be kept in a certain temperature region.
In Example 2, as shown in Table 1, a hydrate was formed by cooling, for example, an 18% aqueous solution having a concentration lower than the harmonic concentration of tri-n-butyl-n-pentylammonium bromide. The melting start temperature of the hydrate below this harmonic concentration was 4 ° C. and the melting end temperature was 6 ° C. The amount of latent heat at the time of melting was 144 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.8 J / g · K. Although the amount of latent heat is less than that of harmonically concentrated hydrates, it can be used as a cryogen that can be kept cold in the range of 4 to 6 ° C.

3) Example 3: Tri-n-butyl-n-pentylammonium chloride (TBPACl) harmonic concentration hydrate The tri-n-butyl-n-pentylammonium chloride hydrate of Example 3 has a harmonic melting point (harmonic concentration of 33) as shown in Table 1. %) Is 9 ° C, the latent heat at the harmonic melting point is 195 J / g, the specific heat of the aqueous solution in which the hydrate is melted is 3.7 J / g · K, and tri-n-butyl-n-pentylammonium bromide hydrate. It can be used as a cryogen having a latent heat amount equivalent to that of.

4) Examples 4, 5, and 6: Mixed hydrate of tri-n-butyl-n-pentylammonium bromide (TBPAB) and tetra-n-butylammonium bromide (TBAB) Harmonic concentration of tri-n-butyl-n-pentylammonium bromide (TBPAB) Hydrate and harmonic concentration hydrate of tetra-n-butylammonium bromide (TBAB) in a weight ratio of 50:50 (Example 4), 30:70 (Example 5), 20:80 (Example 6) The characteristics of the mixed hydrate mixed at a ratio of

As shown in Table 1, these three types of hydrates have a melting temperature of 8 to 9.5 ° C, a latent heat of 182 to 186 J / g, and a specific heat of the aqueous solution in which the hydrate has melted is 3.6 to 3 It is 0.7 J / g · K, and can be used as a cryogen that can be kept cold in the range of 8 to 9.5 ° C.
Further, as can be seen from Table 1, in Examples 4 to 6, the melting temperatures are changed to 8 ° C., 9 ° C., and 9.5 ° C., respectively. From this, by changing the weight ratio between the tri-n-butyl-n-pentylammonium bromide (TBPAB) harmonic hydrate and the tetra-n-butylammonium bromide (TBAB) harmonic hydrate, the desired temperature can be changed. It was confirmed that a mixed hydrate having a melting temperature in the range could be obtained, and the cold keeping temperature of the cryogen could be adjusted.

From the above, as a method for setting the melting point of the cryogen, the cryogen is mainly composed of tri-n-butyl-n-pentylammonium bromide hydrate and tetra-n-butylammonium bromide hydrate. It is conceivable that the blending ratio of n-butyl-n-pentylammonium hydrate and tetra-n-butylammonium bromide hydrate is determined in the range of 1 to 95% by weight.
Each hydrate is preferably a harmonic hydrate. This is because the amount of latent heat can be maximized to keep cold.

  Since the cold insulation performance test was done about said Example 1, 4, the result is demonstrated. In the cold insulation performance test, the cold insulation material in which 3 kg of paraffin (n-tetradecane) was filled in polyethylene bags in Examples 1 and 4 and a comparative example was cooled to 0 ° C. and solidified, and the cold insulation material was used as a vacuum insulation panel. It was attached to the bottom of a 20 l capacity cold box, the cold box was placed in a constant temperature room at 30 ° C., and the temperature change inside the cold box was measured.

1 and 2 are graphs showing the results of the cold insulation performance test. FIG. 1 shows Examples 1 and 2, and FIG. 2 shows a comparative example. In each figure, the vertical axis represents temperature (° C.) and the horizontal axis represents elapsed days (days).
As can be seen from FIG. 1, in Example 1, the temperature inside the cold insulation box remained constant at 6 ° C., and the melting of the cold insulation material was completed after 3.5 days and the temperature rose.
In Example 4, the temperature inside the cold box remained constant at 8 ° C., and the melting of the cold insulator was completed after 3.5 days and the temperature rose.
On the other hand, in the comparative example, the temperature inside the cold insulation box remained constant at 6 ° C., and after 2.7 days had elapsed, melting of the cold insulation material was completed and the temperature rose rapidly.
From the above, it can be seen that Examples 1 and 4 are suitable as a cooling agent because the cooling time is long and the temperature rise after melting is small compared to the comparative example.

  In addition, the said cold insulating agent can also be used as a cooling inhibitor. In other words, when the ambient environment is cooler than the object to be stored, a cooling material filled with a cryogen that is melted around the object to be stored is placed in the container, and when a hydrate is generated from the aqueous solution and solidifies. It absorbs the cold from the surrounding environment and prevents the storage object from cooling. Used to prevent fresh vegetables and foods from freezing in winter and store at an appropriate temperature.

  In the following, although it is not an example of the present invention, since a new use of tetra nbutylammonium salt hydrate that tetra nbutylammonium salt hydrate can be a main component of a cryogen is found, these are used as reference examples. explain. The properties of Reference Examples 1 to 3 are shown in Table 2 below.

A) Reference Example 1
A cryogen mainly composed of an aqueous solution containing tetra-n-butylammonium bromide hydrate having a concentration lower than the concentration (hereinafter referred to as a harmonic concentration) that gives a harmonic melting point of tetra-n-butylammonium bromide hydrate.
In Reference Example 1, as shown in Table 2, a hydrate was produced by cooling, for example, a 22% aqueous solution having a concentration lower than the harmonic concentration of tetra-n-butylammonium bromide. The melting start temperature of the hydrate below this harmonic concentration was 7 ° C., and the melting end temperature was 9 ° C. The latent heat at the time of melting was 140 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.8 J / g · K. Although the amount of latent heat is slightly small, it can be used as a cold-retaining agent that can be kept cold in the range of 7 to 9 ° C.

B) Reference examples 2 and 3
A cryoprotectant comprising tetra-n-butylammonium bromide, a melting point depressant and water.
By adding a melting point depressant to an aqueous solution of tetra nbutylammonium bromide, the melting temperature of tetra nbutylammonium bromide hydrate can be lowered. By appropriately selecting the type and amount of the melting point depressant, it can be used as a cryogen in a desired melting temperature region. As a melting point depressant, an ethylene glycol, propylene glycol, ethyl alcohol or the like having a melting point of 0 ° C. or lower can be added to an aqueous solution of tetra-n-butylammonium bromide to set the melting temperature range to 0 to 10 ° C. .

In Table 2, tetra-n-butylammonium bromide hydrate and ethanol in a weight ratio of 97: 3 (Reference Example 2), tetra-n-butylammonium bromide hydrate and ethylene glycol in a weight ratio of 97: 3 (Reference Example 3).
In Reference Example 2, the melting start temperature was 8 ° C. and the melting end temperature was 10 ° C. The amount of latent heat at the time of melting was 162 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.6 J / g · K. Although the amount of latent heat is slightly small, it can be used as a cold-retaining agent that can be kept cold in the range of 8 to 10 ° C.
In Reference Example 3, the melting start temperature was 8 ° C. and the melting end temperature was 10 ° C. The amount of latent heat at the time of melting was 155 J / g, and the specific heat of the aqueous solution in which the hydrate was melted was 3.6 J / g · K. Although the amount of latent heat is slightly small, it can be used as a cold-retaining agent that can be kept cold in the range of 8 to 10 ° C.

Since the same cold insulation performance test as in Examples 1 and 4 was performed for Reference Examples 1 and 2, the results are shown in FIG. 3 and will be described.
In Reference Example 1, the temperature was 7 ° C. after 8 hours and 9 ° C. after 3 days. The melting of the cold insulating material was completed and the temperature rose.
In Reference Example 2, the temperature was 8 ° C. after 8 hours and 10 ° C. after 3 days, and the melting of the cold insulating material was completed and the temperature rose.
From the above results, it can be used as a cold-retaining agent that can be kept cold in the range of 7-9 ° C or 8-10 ° C.

It is a graph which shows the result of the cold storage performance test of the cold insulating agent which concerns on embodiment of this invention. It is a graph which shows the result of the cold insulation performance test of a comparative example. It is a graph which shows the result of the cold insulation performance test of a reference example.

Claims (11)

A cryoprotectant comprising a tri-n-butylalkylammonium salt and water. A cryogen comprising tri-n-butyl-n-pentylammonium bromide and water. A cryogen characterized by comprising tri-n-butyl-n-pentylammonium bromide hydrate as a main component. A cryoprotectant comprising tri-n-butyl-n-pentylammonium chloride and water. A cryogen characterized by comprising tri-n-butyl-n-pentylammonium chloride hydrate as a main component. A cryogen comprising a tri-n-butylalkylammonium salt, a tetraalkylammonium salt and water. A cooling agent comprising tri-n-butyl-n-pentylammonium bromide, tetra-n-butylammonium bromide and water. A cryogen characterized by comprising tri-n-butyl-n-pentylammonium bromide hydrate and tetra-n-butylammonium bromide hydrate as main components. A cooling agent comprising tri-n-butyl-n-pentylammonium chloride, tetra-n-butylammonium bromide and water. A cryogen characterized by comprising tri-n-butyl-n-pentylammonium chloride hydrate and tetra-n-butylammonium bromide hydrate as main components. A cold insulating material comprising the container or a bag filled with the cold insulating agent according to any one of claims 1 to 10.

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