JPS5952196B2 - Heat medium for cold storage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat transfer medium for cold storage, and its object is to provide a heat transfer medium for a cold storage tool that is flexible and comfortable to use.

Conventionally, water or an aqueous polymer solution has been used as a heat medium in cold storage devices, and these are packed in plastic or rubber bags and used as cold storage devices.

However, these heat carriers freeze and solidify during cold storage at temperatures below 0°C, so when used as an ice pillow, for example, they are very hard and have an extremely poor feel, or the part to be cooled is curved. In some cases, there were drawbacks such as it being extremely difficult to cool the entire system at once.

In order to solve this problem, in recent years, cold storage devices have been proposed that use a water-polyhydric alcohol-based non-freezing heat medium or a 0/W emulsion-based heat medium that can be frozen into a rough texture.

However, in the former case, although it has flexibility, the water does not freeze, so the latent heat of melting of ice cannot be used effectively, and the cooling ability is extremely weak.

In the latter case, since it is an emulsion with water as a continuous phase, it freezes in a rough shape during cold storage, so it retains some flexibility, but the freezing room of a household refrigerator (-10°C to -10°C)
When placed overnight at a temperature of 8°C, it is inevitable that the entire product will freeze solidly. Therefore, in order to provide a heat transfer medium for cooling that is flexible and comfortable to use, the inventors of the present invention have conducted intensive studies on the formulation of water-in-oil emulsions with good stability. When appropriate amounts of chain higher fatty acid aluminum and branched higher fatty acid aluminum are blended, the oily medium not only easily thickens and gels, but also increases the elastic modulus of the W/O boundary layer and improves the stability of the emulsion. The present invention has been completed based on the discovery that the emulsion as a whole has an appropriate elasticity, resulting in a cooling heat medium that is extremely comfortable to use. As the aqueous medium used in the present invention, water itself can sufficiently achieve the purpose, but in order to improve the stability of the emulsion, gelatin, agar, galakian, polyacrylamide, polysaccharide-polyacrylic acid copolymer, etc. It is okay to use one that has been increased with a sticky polymer or made into a viscous gel.

In addition, for the purpose of adjusting the cooling temperature, neutral salts such as sodium chloride and sodium sulfate, lower alcohols such as methanol, ethanol, and propanol, and ethylene glycol, within a range that does not adversely affect the thickening and gelation of the oil-based medium, It is also possible to use an aqueous solution containing polyhydric alcohols such as propylene glycol and glycerin. The oily medium is immiscible with water, and includes liquid oils such as liquid paraffin, spindle oil, and naphthenic oil.

A water-in-oil emulsion prepared according to the mixing ratio of the above aqueous medium and oil-based medium is used as a heat transfer medium for cold storage.However, regarding the mixing ratio of the two, the oil-based medium is selected from the viewpoint of the balance between cooling ability and emulsion stability. It is desirable that the amount of the aqueous medium be 20 to 70% by weight and 80 to 30% by weight of the aqueous medium.

In addition, if the aqueous medium is higher than the above composition ratio, the cold storage ability will improve, but the stability of the emulsion will decrease, and if the oil-based medium is higher than the above composition ratio, the emulsion stability will improve, but the cold storage capacity will decrease. do.

A surfactant is preferably added for the purpose of further promoting and stabilizing the formation of the emulsion. Examples of the surfactant include nonionic surfactants such as sorbitan fatty acid ester, polyoxyalkylene alkyl ether, glycerin fatty acid ester, and propylene glycol fatty acid ester. Examples include surfactants.

Appropriate amounts of linear higher fatty acid aluminum and branched higher fatty acid aluminum are blended for the purpose of thickening and gelatinizing the oily medium. Examples of the linear higher fatty acid aluminum include aluminum trifurylate, aluminum purinate, Those derived from saturated fatty acids having 8 to 20 carbon atoms, such as aluminum laurate, aluminum myristate, aluminum palmitate, and aluminum stearate, are preferably used.

5 These may be used alone or in a mixture of two or more. Note that linear fatty acid aluminum having 7 or less carbon atoms is suitable because it has extremely low solubility in oily media. The branched higher fatty acid aluminum may have 48 to 20 carbon atoms, such as aluminum 2-ethylhexanoate,
Examples include aluminum isocaprate, aluminum isolaurate, and aluminum isostearate.

j The weight ratio of linear higher fatty acid aluminum and branched higher fatty acid aluminum is preferably in the range of 7:3 to 2:8. The amount added varies depending on the type and composition ratio, so it is best to select the appropriate amount necessary to obtain the desired flexibility, but usually 1 to 20 parts by weight per 100 parts by weight of the oil-based medium is sufficient. .

In addition to adding the fatty acid aluminum mentioned above, condensates of benzaldehyde and polyhydric alcohols, N-acylamino acid amides, N-acylamino acid esters, polysaccharide fatty acid esters, etc., which are conventionally used as thickening and gelling agents for oily media, are used as appropriate. These oil-based medium 1
It is preferable to add 0.1 to 5 parts by weight per 00 parts by weight. To prepare the heat transfer medium for cold storage of the present invention, after dissolving or dispersing the surfactant in an oily medium, an aqueous medium is added. A water-in-oil emulsion is prepared, then linear higher fatty acid aluminum and branched fatty acid aluminum are added simultaneously or separately and uniformly dispersed.

Alternatively, a water-in-oil emulsion may be prepared by previously dispersing linear higher fatty acid aluminum and branched higher fatty acid aluminum in an oily medium and then adding an aqueous medium. Further, if necessary, thickening and gelation can be promoted by heating in order to stabilize the emulsion and give it appropriate elasticity.

Also, a condensate of benzaldehyde and polyhydric alcohol, N
- When using other types of thickening gelling agents such as acylamino acid amide, N-acylamino acid ester, and polysaccharide fatty acid ester, they may be added in the step of adding fatty acid aluminum.

When the heat transfer medium for cold storage prepared according to the present invention is sealed in a plastic bag and used as a cold insulation pillow, it maintains appropriate flexibility even when cold is stored continuously for more than two days and nights in the freezer compartment of a household refrigerator. Because of this, the feeling of use and the durability of cold storage are extremely good.

Hereinafter, this will be explained in detail using examples. In the examples, parts mean parts by weight. Example 1 1 part of sorbitan monooleate in 100 parts of liquid paraffin
0 parts was dissolved, and 100 parts of water was gradually added thereto over 30 minutes while stirring to obtain a water-in-oil emulsion.

5 parts of aluminum 2-ethylhexanoate and 5 parts of aluminum stearate were added to this emulsion, stirred and dispersed uniformly, and then 500θ was packed into a 15 x 20 rectangular polyethylene bag and heat-sealed, then placed in a 60°C water bath. The mixture was immersed in water for 90 minutes and heated to thicken it into a gel, which was then used as a cold pillow.

. . ,,'． 1℃
When it was left at room temperature, it took 6 hours for the temperature to rise to 5°C, indicating an excellent cold retention effect.

Moreover, this product had appropriate elasticity in the temperature range from immediately after freezing to 25° C., and was excellent in feel when used as a cold pillow. Example 2 A water-in-oil emulsion was obtained in the same manner as in Example 1 using 100 parts of liquid paraffin, 6 parts of sorbitan monopalmitate, and 100 parts of water.

A total of 10 g of aluminum 2-ethylhexanoate and aluminum stearate were added to this emulsion 1009 at various mixing ratios, uniformly mixed and dispersed, and then heated at 60° C. for 90 minutes to form a thickened gel. This thickened gelled emulsion is about 50 fl (diameter 45 l) height 75
After placing it in a glass pin No. 1 and leaving it to cool to 25°C, the stress when a stainless steel cylindrical plunger with a diameter of 101 mm penetrates into the sample was measured using a rheometer No. 1 (manufactured by Fudo Kogyo KK), and the elasticity value ( 9/Cln) was determined, and the results are shown as 1 in FIG. Furthermore, the above sample was heated to -10°C to -1
After freezing overnight in a freezer at 8°C, elasticity values were determined in the same manner.

The results are shown in FIG. 1. From FIG. 1, it is clear that when aluminum stearate and aluminum 2-ethylhexadiate are blended into a water-in-oil emulsion, the elasticity value increases mutually.

In addition, a cold pillow was prepared using a thickened gelled emulsion obtained by blending aluminum stearate and aluminum 2-ethylhexanoate at a ratio of 7:3 to 2:8, and frozen (-1
Even after repeating 10 times of thawing (0°C to -18°C) and thawing (25°C), no ice lumps were formed and the stability of the emulsion was good.

Example 3 100 parts of the water-in-oil emulsion prepared in Example 2 were blended with various linear fatty acid aluminum and branched fatty acid aluminum in the proportions shown in Table 1, and heated at 80°C.
After heating for 30 minutes, the mixture was allowed to cool to room temperature to obtain a thickened gelled emulsion.

Elasticity values and freezing (−
Table 1 shows the stability against a test of 10 times repeated thawing (25°C) (10°C to -18°C).

As is clear from Table 1, the thickened gel emulsion obtained by blending linear fatty acid aluminum and branched fatty acid aluminum has elasticity and stability, and has a very good feeling when used as a cold pillow. It was good and warm.

Furthermore, the cold storage performance of these samples was almost the same as that of Example 1 and was satisfactory. Example 4 Solbitan monolaurate 1009 was dissolved in 1000 f1 of spindle oil and dissolved in 900 g of water while stirring for 30 minutes.
g was added to obtain a water-in-oil emulsion.

To 500g of this emulsion, 159% of aluminum 2-ethylhexanoate and 109% of aluminum n-stearate were added.
(a) is a mixture and dispersion of N-
Lauroyl glutamic acid monoalpha, gamma monodibutylamide 5g
(b) is the mixture and dispersion of 15 x 20 d.
After being packed in a polyethylene bag and heat-sealed, it was heated to 80℃.
A cold pillow was prepared by immersing the pillow in a hot water bath for 60 minutes, heating it, and then cooling it to room temperature.

This cold pillow was frozen overnight in a freezer at -10 to -18°C, and then thawed in running water at 25°C.
After 0 repetitions, the rate of decrease in elasticity was approximately 1 in (a).
0%, and about 5% for (b), indicating that (b) had better elasticity stability. The stability of both emulsions was good, and they maintained uniform and flexible physical properties as a whole.

[Brief explanation of drawings]

FIG. 1 shows the relationship between the mixing ratio of aluminum 2-ethylhexanoate and n-aluminum stearate and the elasticity of the thickened gelled emulsion in Example 2.

Claims (1)

[Claims] 1. 20 to 70% by weight of an oily medium containing appropriate amounts of linear higher fatty acid aluminum and branched higher fatty acid aluminum
A heat transfer medium for cold storage, characterized in that it is a water-in-oil emulsion consisting of 80 to 30% by weight of an aqueous medium. 2. The heat medium for cold preservation according to claim 1, wherein the linear higher fatty acid aluminum and the branched higher fatty acid aluminum are each saturated fatty acid aluminum having 8 to 20 carbon atoms. 3 Straight chain higher fatty acid aluminum and branched higher fatty acid aluminum at a weight ratio of 7:3 to 2:8,
The heat medium for cold preservation according to claim 1, wherein the total amount is 1 to 20 parts by weight based on 100 parts by weight of the oil-based medium.