JP2022014751A - Heat storage nucleating agent, heat storage medium, and method for producing the same - Google Patents

Abstract

To provide: a heat storage nucleating agent having excellent nucleating properties, a heat storage medium that can suppress supercooling and has high repeated coagulation stability, and a method for producing the heat storage medium.SOLUTION: Provided are: a heat storage nucleating agent containing resin particles on which nucleus-forming nuclear seeds are supported; and a heat storage medium containing a salt hydrate and resin particles holding nucleus-forming nuclear seeds on the surfaces thereof.SELECTED DRAWING: None

Description

The present invention relates to a heat storage nucleating agent, a heat storage material, and a method for producing the heat storage material.

Conventionally, latent heat storage materials that utilize the transition heat of phase change materials have been widely used for effective utilization of nighttime electric power and applications for heat and cold insulation agents. In particular, a salt hydrate-based heat storage material having a relatively low temperature and a large latent heat is attractive as a household energy saving measure, and various materials and compositions have been proposed for smart houses such as air conditioners and heat storage heat insulating materials.

In recent years, the salt hydrate-based heat storage material has been attracting attention as a measure against heat generation of smartphone CPUs and batteries, which require repeated cooling and solidification in a relatively short time as smartphones become faster and have higher performance. ing.
Such sodium acetate trihydrate (SAT) is a salt hydrate having relatively good coagulation reproducibility due to its small hydration number, and has a melting point of 58 ° C., which is close to the living temperature, and phosphorus. The acid salt functions as a nuclear catalyst for sodium acetate trihydrate (SAT), and can be repeatedly thawed and coagulated by the addition of disodium hydrogen phosphate (DSP) and tetrasodium pyrophosphate (TSPP). It is disclosed (see, for example, Non-Patent Document 1).
Further, it is disclosed that the refractory hydrate (dihydrate) of disodium hydrogen phosphate (DSP) is a nuclide nuclide (see, for example, Patent Document 1).

However, the above-mentioned high melting point hydrate or sparingly soluble salt tends to precipitate and separate when the sodium acetate trihydrate (SAT) is thawed, and in the cooling process, from the interface with the precipitated nucleating compound. Since crystallization starts gradually, it is difficult to solidify in a short time. That is, there is a problem that supercooling is large.
Therefore, for example, it has been proposed to use an alkyl surfactant having sodium phosphate at the terminal such as sodium dodecyl phosphate (SLP) as a nucleating compound (see, for example, Patent Document 2).

The above-mentioned sodium dodecyl phosphate (SLP) does not dissolve in the melt of sodium acetate trihydrate (SAT), and sodium dodecyl phosphate has a small true density and does not precipitate, so that it is compared with phosphate or the like. It is effective as a nuclear catalyst, suppresses the supercooling phenomenon, and can repeat melting and solidification in a relatively short time, but has the following problems.
(1) Since dodecyl sodium phosphate is an alkyl surfactant that is sparingly soluble in water, most of it is separated as an aggregated solid, and the existence state varies depending on the collection location.
(2) Since sodium dodecyl phosphate has a low true density, it floats when the salt hydrate is thawed, and the separation to the upper part becomes remarkable especially when the amount of the salt hydrate is large.

Therefore, for the above reasons, sodium dodecyl phosphate has a problem that the nuclear function is not stable depending on the amount of melting, the melting time, the collection place, the collection method, and the like, and the coagulation reproducibility is insufficient.

Japanese Patent No. 6423870 Japanese Patent No. 6045944

STUDIES ON SODIUM ACETATE TRIHYDRATE FOR LATENTHEAT STORAGE_Takahiro Wada (Osaka University Knowledge Archive: OKA)

An object of the present invention is to solve the above-mentioned problems in the prior art and to achieve the following objects. That is, an object of the present invention is to provide a heat storage nucleating agent having good nucleating properties, a heat storage material capable of suppressing supercooling and having high repetitive solidification stability, and a method for producing the heat storage material.

The means for solving the above problems are as follows. That is,
<1> A heat storage nuclide agent characterized by containing resin particles carrying a nuclide nuclide.
<2> The heat storage nucleating agent according to <1>, wherein the volume average particle size of the resin particles is 0.05 μm or more and 1.0 μm or less.
<3> The resin particles are the heat storage nucleating agent according to any one of <1> to <2>, which contains surface-basic amino-based resin particles.
<4> The heat storage nucleating agent according to <3>, wherein the surface-based amino resin particles are at least one of melamine resin particles, benzoguanamine resin particles, and urea resin particles.
<5> The heat storage nuclide according to any one of <1> to <4>, wherein the nuclide nuclide is disodium hydrogen phosphate or disodium tetraborate.
<6> A heat storage material characterized by containing resin particles holding nuclide nuclides on the surface and salt hydrate.
<7> The heat storage material according to <6>, wherein the difference (AB) between the true density A of the resin particles and the true density B of the salt hydrate is within ± 0.25 g / cm ³ .
<8> The heat storage material according to any one of <6> to <7>, wherein the volume average particle size of the resin particles is 0.05 μm or more and 1.0 μm or less.
<9> The resin particles are the heat storage materials according to any one of <6> to <8>, which contain surface-basic amino-based resin particles.
<10> The heat storage material according to <9>, wherein the surface-based amino resin particles are at least one of melamine resin particles, benzoguanamine resin particles, and urea resin particles.
<11> The nuclide nuclide is disodium hydrogen phosphate or disodium tetraborate.
The heat storage material according to any one of <6> to <10>, wherein the salt hydrate is sodium acetate trihydrate or sodium sulfate decahydrate.
<12> The heat storage material according to any one of <6> to <11>, which can be repeatedly melted and solidified.
<13> A step of adding resin particles to a nucleating compound dissolved in a solvent, mixing and dispersing the mixture, and then pulverizing the dried product obtained by drying.
The step of adding the obtained ground product to the salt hydrate,
It is a method of manufacturing a heat storage material characterized by containing.

According to the present invention, it is possible to provide a heat storage nucleating agent having good nucleating properties, a heat storage material capable of suppressing supercooling and having high repetitive solidification stability, and a method for producing the heat storage material.

FIG. 1 is a schematic view showing an example of a state in which sodium phosphate is supported on the surface of amino resin particles. (A) to (C) of FIG. 2 are schematic views showing an example of the state of existence of a nucleating compound in a melt of salt hydrate. FIG. 3 is a photograph showing that when sodium dodecyl phosphate (alkyl surfactant) is used as the nucleating compound, sodium dodecyl phosphate is separated into the upper part of the melt of salt hydrate. FIG. 4 is a photograph showing that when the heat storage nucleating agent of the present invention is used, it is uniformly dispersed throughout in the melt of salt hydrate. FIG. 5 shows No. 1 in Example 1. It is a DSC chart measured about 3 heat storage materials. FIG. 6 shows No. 6 in Example 2. It is a DSC chart measured about 9 heat storage materials. FIG. 7 shows No. 7 in Example 2. It is a DSC chart when the heat storage material of 9 was measured continuously for 10 cycles. FIG. 8 shows No. 3 in Example 3. It is a DSC chart measured about 3 heat storage materials.

(Nucleating agent for heat storage)
The heat storage nuclide of the present invention contains resin particles carrying a nuclide nuclide. The nuclide nuclide may also be referred to as a "nuclide agent", a "nucleation catalyst", a "nucleation promoter", or a "nucleation catalyst".

Here, the above-mentioned "the nucleating nuclei are carried on the resin particles" means that the nucleating nuclei exist in an arbitrary interacting state such as attachment, adhesion, adsorption, and van der Waals bond to the resin particles. It means that it exists in any chemically bonded state such as a covalent bond, an ionic bond, a hydrogen bond, or a metal bond. It should be noted that at least a part of the nuclide nuclide and the resin particles may be chemically bonded, most of them may be chemically bonded, and a case where they are not chemically bonded is also included.
The fact that the resin particles carry the nucleating nuclei can be confirmed by analysis by, for example, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), neutralization titration method or the like.

<Nuclide nuclide>
The nucleating nuclei are not particularly limited as long as they have nucleating properties, and can be appropriately selected depending on the intended purpose. For example, disodium hydrogen phosphate, disodium tetraborate, and phosphoric acid 3 can be selected. Examples thereof include sodium, tetrasodium pyrophosphate, and sodium alkylphosphate.

In the present invention, as a nucleating compound having affinity with a salt hydrate melt and not precipitating or floating-separating, a phosphate as a nucleating nuclei is supported on the surface of resin particles having a similar true density. Is used as a nucleating agent for heat storage. As a result, the nucleating compound is uniformly distributed in the salt hydrate melt without sedimentation or floating separation, and stable solidification reproducibility can be obtained regardless of the collection location and collection method.
The treated amount (supported amount) of the nuclide nuclide with respect to the resin particles is preferably 5% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 15% by mass or less.

<Resin particles>
The resin particles are not particularly limited and may be appropriately selected depending on the intended purpose, but surface-basic amino resin particles are preferable from the viewpoint of carrying phosphate.
Examples of the surface basic amino resin particles include melamine resin particles, benzoguanamine resin particles, urea resin particles and the like. Among these, when sodium acetate trihydrate is used as the salt hydrate, melamine resin particles are preferable because the true density is about the same as that of the sodium acetate trihydrate.

The volume average particle size of the resin particles is preferably 0.05 μm or more and 1.0 μm or less, and more preferably 0.05 μm or more and 0.5 μm or less.
When colloid-sized resin particles having a volume average particle diameter of 0.05 μm or more and 1.0 μm or less are used, the melt of salt hydrate becomes a stable emulsion state for a long time. Further, since the nuclide nuclides are distributed in the microscopic region, there is no unevenness depending on the collection place and collection method, and stable nuclides and solidification reproducibility can be obtained even with a large amount of salt hydrate.
The volume average particle size of the resin particles can be calculated by actual measurement from an image observed under a microscope, but an optical particle size measuring device such as a commercially available laser diffraction / scattering method or a photon correlation method (dynamic scattering method) can be used. It can be measured by using it, and can be measured by using, for example, Microtrac MT3300EX (Microtrac Bell Co., Ltd.), Partica LA-960 (manufactured by Horiba Seisakusho Co., Ltd.) and the like.

The heat storage material of the present invention can be obtained by combining the resin particles (heat storage nuclides) carrying the nuclide nuclides with the salt hydrate described later.
The difference (AB) between the true density A of the resin particles and the true density B of the salt hydrate is preferably within ± 0.25 g / cm ³ , and more preferably within ± 0.1 g / cm ³ . When the difference (AB) is within ± 0.25 g / cm ³ , the true density of the resin particles and the true density of the salt hydrate are about the same, so that the salt hydrate is stably dispersed in a milky liquid when melted. Therefore, it is possible to obtain a heat storage material that can be repeatedly solidified without component separation.
As the method for measuring the true density, for example, there are various methods such as a specific gravity cup, a submersible method, and a gas substitution method as described in JIS Z8807: 2012, but in the present invention, they are organic substances. Since resin particles are used, the gas substitution method is suitable. Examples of the gas substitution method include Accu Pyc II 1340 (manufactured by Micromeritics).

In the prior art, salt hydrates such as sodium acetate trihydrate and sodium sulfate hydrate have attracted attention as heat storage materials having high latent heat, and various materials and substances have been used as nucleating nuclei to prevent supercooling. Although it has been studied, there is a problem that the coagulation reproducibility in a short time is poor due to the separation of the components at the time of thawing, and the use is limited.
As a result of diligent studies to solve the above problems, the present inventors have found that the resin particles surface-treated (supported) with sodium phosphate or sodium borate have excellent nucleation. Further, by using colloid-sized resin particles (nanoparticles) having the same true density as the salt hydrate and having a volume average particle size of 0.05 μm or more and 1.0 μm or less, the salt hydrate becomes a milky lotion when it is thawed. A heat storage material that can be stably dispersed in a stable manner without component separation and can be repeatedly solidified can be obtained, and the amount of resin particles carrying sodium phosphate or sodium borate is several mass% with respect to the salt hydrate. It has been found that since it is effective with a small amount of addition, the latent heat amount does not decrease much and a high latent heat storage material can be obtained. As a result, it is particularly suitable for applications that require repeated cooling and solidification in a relatively short time, such as cooling the CPU and battery of a smartphone.

Here, when disodium hydrogen phosphate hydrate is used as the nucleating compound and melamine resin particles are used as the resin particles, the amino group on the surface of the melamine resin particles and the OH group of disodium hydrogen phosphate are ions. It is believed to exist in combination. Preferred examples thereof include a mode in which the nuclide nuclide and the resin particles are covalently bonded, and a mode in which the nuclide nuclide is graft-polymerized on the surface of the resin particles.

In the present invention, resin particles carrying a nuclide nuclide, which satisfy the following conditions, are used as a heat storage nuclide.
(1) A salt hydrate-based heat storage material having high latent heat such as sodium acetate trihydrate, which is surfaced with a nucleating nuclei such as sodium phosphate as a heat storage nucleating agent for preventing supercooling. Use treated resin particles.
(2) Use resin particles having a true density close to that of salt hydrate (for example, melamine resin particles having a true density of about 1.5 g / cm ³ ).
(3) As the resin particles, colloid-sized fine particles (nanoparticles) having a volume average particle diameter of 0.05 μm or more and 1.0 μm or less are used.
By filling the above (1) to (3), the true density of the resin particles becomes close to the true density of the salt hydrate, and since the volume average particle size of the resin particles is a colloidal size, when the salt hydrate is thawed. It does not settle, float and separate, and shows good nucleation. As a result, a heat storage material that suppresses supercooling and has high repeated solidification stability can be obtained.

Here, as shown in FIG. 2A, in the present invention, the resin particles carrying the nuclide nuclides are uniformly distributed in the melted salt hydrate without sedimentation and suspension, and the collection place. Stable solidification reproducibility can be obtained regardless of the sampling method. As shown in FIG. 2B, when dodecyl sodium phosphate (alkyl surfactant) is used as a nucleating compound having a low true density, the surfactant floats on the surface of the melted salt hydrate. .. As shown in FIG. 2C, if a nucleating compound having a high true density is used, it will settle in the melted salt hydrate.
Further, FIG. 3 shows that when sodium dodecyl phosphate (alkyl surfactant) is used as a nucleating compound having a low true density, sodium dodecyl phosphate is separated into the upper part of the melt of salt hydrate. It is a photograph showing. FIG. 4 is a photograph showing that when the heat storage nucleating agent of the present invention is used, it is uniformly dispersed throughout in the melt of salt hydrate.

(Heat storage material)
The heat storage material of the present invention contains resin particles that retain nuclides on the surface and salt hydrate, and further contains other components as necessary.
Since the heat storage material can repeatedly melt and solidify in a relatively short time, it is particularly preferably used for cooling a CPU or a battery of a smartphone.

<Resin particles holding nuclide nuclides on the surface>
As the resin particles that retain the nuclide nuclide on the surface, the heat storage nuclide of the present invention is used.

<Salt hydrate>
Examples of the salt hydrate include sodium acetate trihydrate, sodium sulfate decahydrate and the like.
Sodium acetate trihydrate is a salt hydrate having good coagulation reproducibility due to its small hydration number, and is preferable because it has a melting point of 58 ° C. and is close to the living temperature.

In the heat storage material of the present invention, the content of the resin particles that retain the nuclide nuclide on the surface is preferably 0.5% by mass or more and 5% by mass or less, and 1% by mass or more and 4% by mass with respect to the salt hydrate. The following is more preferable.

<Other ingredients>
The other components are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include formamide and urea. By adding a predetermined amount of formamide or urea to sodium acetate trihydrate, a eutectic compound having a melting point of around 40 ° C. can be formed.

(Manufacturing method of heat storage material)
The method for producing a heat storage material of the present invention includes a step of adding resin particles to a nucleating compound dissolved in a solvent, mixing and dispersing the mixture, and then pulverizing the dried product obtained by drying, and salt hydration of the obtained pulverized product. It includes a step of adding to a substance, and further includes other steps as necessary. This makes it possible to efficiently produce resin particles that retain nuclides on the surface.

The nuclide compound is a compound that becomes a nuclide nuclide when supported on the surface of resin particles, and examples thereof include hydrates of the nuclide nuclide.
Examples of the nucleating compound include hydrogen phosphate disodium dodecahydrate, tetraborate disodium hydrate, hydrogen phosphate disodium disodium dihydrate, pyrophosphate tetrasodium hydrate, and alkyl phosphate. Examples include sodium.
The solvent is not particularly limited and may be appropriately selected depending on the type of the nucleating compound, and examples thereof include water, alcohol and hydrocarbons. These may be used alone or in combination of two or more.
Examples of the alcohol include methanol, ethanol, isopropyl alcohol and the like.
Examples of the hydrocarbon include n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, and the like. Examples include ethylbenzene and cumene.

The drying temperature is not particularly limited and may be appropriately selected depending on the type of the nucleating compound to be used, but is preferably 60 ° C. or higher and 100 ° C. or lower.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

<Measurement of true density>
The true density of the particles could be measured by the gas substitution method and was measured using a dry automatic density meter (Accu Pyc II 1340, manufactured by Micromeritics).

<Measurement of volume average particle size>
The volume average particle size of particles can be measured using an optical particle size measuring device such as a commercially available laser diffraction / scattering method or photon correlation method (dynamic scattering method). Microtrac MT3300EX (Microtrac Bell Co., Ltd.) Measurement was performed using (company) or Partica LA-960 (manufactured by Horiba Seisakusho Co., Ltd.).

(Example 1)
<Selection of particles>
Particles carrying nuclide nuclides were selected as follows.
-Preparation of treated particles-
1 g of disodium hydrogen phosphate dodecahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 4 mL of pure water. 1 g of each particle shown in Table 1-1 was added to this solution, and the mixture was mixed and stirred to prepare a slurry. The obtained slurry was dried at 60 ° C. using a hot air circulation oven, dried under reduced pressure, and the dried product was pulverized to prepare sodium phosphate-treated particles A-1 to A-4 shown in Table 1-2. did.

-Making heat storage material-
Next, take 5 g of sodium acetate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) in a 10 mL glass bottle, add 1.25 g of formamide (manufactured by Wako Pure Chemical Industries, Ltd., special grade) to this, and add each. 1.0% by mass of treated particles A-1 to A-4 were added, and these were melted at 60 ° C. to obtain No. 1 to 4 milky white liquids (heat storage materials) were obtained.

Next, for each of the obtained heat storage materials, the cycle stability was evaluated as follows, and the latent heat (heat of solidification) in the second cycle was measured. The results are shown in Table 1-2.

<Evaluation of cycle stability and measurement of latent heat in the second cycle>
Each of the obtained heat storage materials was collected in a measurement cell, and the thermal characteristics at the time of temperature rise and temperature decrease were measured with a differential scanning calorimeter (DSC) under the following measurement conditions.
In addition, No. The DSC chart measured for the heat storage material of No. 3 is shown in FIG. From the results of FIG. 5, the melting point (endothermic start temperature at the time of melting) was about 41 ° C., and the freezing point (heat generation start temperature at the time of solidification) was about 37 ° C.
In addition, No. When the amount of heat was calculated from the area of the endothermic and heat generation peaks of the heat storage material of No. 3, a high latent heat of 234 mJ / mg was observed.
Next, the cycle stability of each heat storage material was evaluated based on the following evaluation criteria. The results are shown in Table 1-2.

[Evaluation criteria for cycle stability]
〇: Stable melting / solidification for 2 cycles Δ: Melting / solidifying for 2 cycles but delay in solidification or large decrease in latent heat ×: Stable melting / solidification is not observed within the measurement cycle

-Measurement condition-
-Differential scanning calorimeter: DSC7000X (manufactured by Hitachi High-Tech Science Corporation)
-Sealed cell: Aluminum (Al), 15 μL (Hitachi High-Tech Science Corporation, GCA-017)
・ Temperature range: 20 ° C to 50 ° C, elevating temperature rate 2 ° C / min ・ Measurement frequency: 2 to 10 cycles

From the results of Table 1-2 and FIG. 5, the sodium phosphate-treated particles of A-3 were repeatedly thawed and solidified at a melting point of about 41 ° C. and a freezing point of about 37 ° C., and the carried sodium phosphate was a nuclear catalyst. It turned out to work as. The sodium phosphate-treated melamine resin particles of A-3 having a true density of 1.50 g / cm ³ and close to the true density of sodium acetate trihydrate (1.43 g / cm ³ ) are sodium acetate trihydrate. It was found that it was stably dispersed in the melt of Japanese product and had good solidification reproducibility.
In contrast, the sodium phosphate-treated crosslinked PMMA fine particles of A-1 and A-2 have a true density of 1.19 g / cm ³ , which is smaller than the true density of sodium acetate trihydrate. It was found that the solidification reproducibility was inferior because it floated on the surface of the hydrate melt.
Further, it was found that since the true density of A-4 sodium phosphate-treated silica gel was 2 g / cm ³ or more, it settled in the melt of sodium acetate trihydrate, and the coagulation reproducibility was poor.

From the above results, in the following Examples and Comparative Examples, the melamine resin particles (manufactured by Nippon Catalyst Co., Ltd., Epostal SS, melamine / formaldehyde condensate, volume average particle size 0.1 μm, true density 1.50 g /) were used as the supporting particles. cm ³ ) was used.

(Example 2)
<Treatment amount of disodium hydrogen phosphate for resin particles>
As shown in Table 2, treatment with disodium hydrogen phosphate (Na ₂ HPO ₄ ) was carried out in the same manner as in Example 1 except that the addition ratios of disodium hydrogen phosphate dodecahydrate and melamine resin particles were changed. Sodium phosphate-treated resin particles of B-1 to B-4 in different amounts were prepared.

<Making heat storage material>
Next, take 5 g of sodium acetate trihydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) in a 10 mL glass bottle, and add 1.25 g of formamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) to the treatment. Resin particles B-1 to B-4 were added in the amounts shown in Table 3, and these were melted at 60 ° C. to obtain No. 1 to 13 milky white liquids (heat storage materials) were obtained. In addition, No. 8 and No. For 9, the amount of sodium acetate trihydrate was 60 g.
After the completion of heating, solidification started within 10 minutes, and the solid became a milky white solid without layer separation.
Next, in order to measure the thermal characteristics, sampling was performed in a liquid state, or the mixture was cooled to room temperature, solidified, crushed, and sampled as a powder.

Next, for each of the obtained heat storage materials shown in Table 3, the cycle stability was evaluated and the latent heat (heat of solidification) in the second cycle was measured as follows. The results are shown in Table 3.

<Evaluation of cycle stability and measurement of latent heat in the second cycle>
Each of the obtained heat storage materials was collected in a measurement cell, and the thermal characteristics at the time of temperature rise and temperature decrease were measured with a differential scanning calorimeter (DSC) under the same measurement conditions as in Example 1 above.
In addition, No. The DSC chart measured for the heat storage material of 9 is shown in FIG. In addition, No. The DSC chart of the heat storage material of 9 when continuously measured for 10 cycles is shown in FIG.
From the results of FIG. 6, the melting point (endothermic start temperature at the time of melting) was about 41 ° C., and the freezing point (heat generation start temperature at the time of solidification) was about 37 ° C.
In addition, No. When the amount of heat was calculated from the area of the endothermic and heat generation peaks of the heat storage material of No. 9, high latent heat of 250 mJ / mg was observed.
In addition, the cycle stability of each heat storage material was evaluated based on the same evaluation criteria as in Example 1. The results are shown in Table 3.

＊表３中の２サイクル目の潜熱が「－」は、凝固しなかったため、測定不能であることを示す。

* If the latent heat of the second cycle in Table 3 is "-", it means that it cannot be measured because it did not solidify.

From the results in Table 3, the amount of disodium hydrogen phosphate treated with respect to the melamine resin particles was 7% by mass or more and 28% by mass or less, the amount of the melamine resin particles added to the sodium acetate trihydrate was 1.0% by mass or more, and acetic acid. It was found that good cycle stability and high latent calorific value can be obtained when the concentration of disodium hydrogen phosphate with respect to sodium trihydrate is about 0.3% by mass or more and 0.6% by mass or less.
In addition, No. 8 and No. From the results of No. 9, it was confirmed that stable coagulation reproducibility can be obtained regardless of the collection method even if the amount of sodium acetate trihydrate added is increased to 60 g.

(Comparative Example 1)
Take 5 g of sodium acetate trihydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) in a 10 mL glass bottle, add 1.25 g of formamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade) to this, and add hydrogen phosphate 2 1.0% by mass of sodium 12 hydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) was added and melted at 60 ° C. to prepare a transparent liquid (heat storage material).

(Comparative Example 2)
A heat storage material was prepared in the same manner as in Comparative Example 1 except that 3.0% by mass of disodium hydrogen phosphate dodecahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) was added in Comparative Example 1. ..

(Comparative Example 3)
In Comparative Example 1, 1.0% by mass of disodium hydrogen phosphate dodecahydrate was changed to 3.0% by mass of tetrasodium pyrophosphate decahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade). Made a heat storage material in the same manner as in Comparative Example 1.

(Comparative Example 4)
In Comparative Example 1, Comparative Example 1 except that 1.0% by mass of disodium hydrogen phosphate dodecahydrate was changed to 1.0% by mass of monododecyl sodium phosphate (manufactured by Tokyo Kasei Kogyo Co., Ltd., special grade). In the same manner as above, a heat storage material was produced.

(Comparative Example 5)
In Comparative Example 1, 1.0% by mass of disodium hydrogen phosphate dodecahydrate was changed to 1.0% by mass of monododecyl sodium phosphate (manufactured by Tokyo Kasei Kogyo Co., Ltd., special grade), and sodium acetate trihydrate was changed. A heat storage material was produced in the same manner as in Comparative Example 1 except that 5 g was changed to 60 g.

(Comparative Example 6)
In Comparative Example 1, Comparative Example 1 except that 1.0% by mass of disodium hydrogen phosphate dodecahydrate was changed to 5.0% by mass of monododecyl sodium phosphate (manufactured by Tokyo Kasei Kogyo Co., Ltd., special grade). In the same manner as above, a heat storage material was produced.

Next, with respect to the obtained heat storage materials of Comparative Examples 1 to 6, the cycle stability was evaluated in the same manner as in Example 1, and the latent heat (heat of solidification) in the second cycle was measured. The results are shown in Table 4.

表４の結果から、比較例１～３の樹脂粒子に担持しないリン酸塩系結晶単独では発核性を示すものの、凝固遅れによるピーク分離や潜熱低下が見られた。
また、比較例４及び６では、アルキルリン酸エステルとしてのリン酸モノドデシルナトリウムは塩水和物としての酢酸ナトリウム三水和物が少量の時はサイクル安定性が見られたが、凝固再現性が乏しかった。また、比較例５のように塩水和物の添加量が多量である場合には、浮遊分離してしまい良好な発核性が得られなかった。

From the results in Table 4, although the phosphate-based crystals alone not supported on the resin particles of Comparative Examples 1 to 3 showed nucleation, peak separation and a decrease in latent heat due to the delay in solidification were observed.
Further, in Comparative Examples 4 and 6, the sodium phosphate monododecyl as an alkyl phosphate ester showed cycle stability when the amount of sodium acetate trihydrate as a salt hydrate was small, but the coagulation reproducibility was high. It was scarce. Further, when the amount of salt hydrate added was large as in Comparative Example 5, suspension separation occurred and good nucleation could not be obtained.

From the above results, it was found that stable repetitive coagulation reproducibility can be obtained by using resin particles surface-treated with sodium phosphate as a heat storage nucleating agent for sodium acetate trihydrate.
Further, it was found that melamine resin particles having a true density of 1.50 g / cm ³ are suitable as the resin particles.
Further, it was found that the resin particles preferably have colloidal size fine particles having a volume average particle size of 0.05 μm or more and 1.0 μm or less.
Further, it was found that the treatment amount of sodium phosphate with respect to the resin particles is preferably 7.3% by mass or more and 28.4% by mass or less.
Further, the content of the resin particles is preferably 1% by mass or more and 4.0% by mass or less, and when converted as a concentration with respect to sodium acetate trihydrate, 0.3% by mass or more and 0.6% by mass or less is effective. all right.

(Example 3)
<Preparation of resin particles C-1 treated with disodium tetraborate>
As shown in Table 6, 1.0 g of disodium tetraborate decahydrate is dissolved in 30.0 ml of pure water, and melamine resin particles (manufactured by Nippon Catalyst Co., Ltd., Epostal SS, melamine / formaldehyde condensate) are dissolved in this solution. , Average particle size 0.1 μm, true density 1.5 g / cm ³ ) 1.0 g was added and mixed, and heated at 80 ° C. for 25 minutes to obtain a suspension.
Next, the obtained suspension was dried at 80 ° C. in a hot air circulation oven, dried under reduced pressure, and pulverized to obtain disodium tetraborate-treated resin particles C-1.

<Making heat storage material>
As a salt hydrate, take 5 g of sodium sulfate decahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special grade) in a 10 mL glass bottle, add the treated resin particles C-1 to this in the amount shown in Table 7, and set the temperature at 50 ° C. Melted in No. 1 to 4 milky white creamy liquids (heat storage materials) were obtained.

<Measurement of thermal characteristics>
In order to measure the thermal characteristics, sampling was performed with the liquid melted again after solidification, DSC measurement was performed in the same manner as in Example 1, cycle stability was evaluated, and latent heat in the second cycle was measured. The results are shown in Table 7. In addition, No. The DSC chart measured for the heat storage material of No. 3 is shown in FIG.

図８の結果から、融点約３３℃、凝固点約２６℃での繰返し融解及び凝固が認められた。このことから、四ホウ酸２ナトリウムを担持した樹脂粒子Ｃ－１が硫酸ナトリウム１０水和物の発核触媒として機能していることがわかった。
従来から、四ホウ酸２ナトリウムはその結晶格子サイズの類似性から、硫酸ナトリウム１０水和物がエピタキシャル成長可能な発核性核種として知られている。しかし、ホウ酸ナトリウム結晶は溶解し難いこと、また、硫酸ナトリウム水和物は不調和融解して無水硫酸ナトリウムが沈降することから、短時間での安定な繰返し凝固が難しかった。
表７の結果から、四ホウ酸２ナトリウムを担持した樹脂粒子を蓄熱用発核剤として用いることにより、硫酸ナトリウムの融解液がクリーム状となり成分分離が少ないことから、繰返し凝固安定性が高い硫酸ナトリウム水和物系の蓄熱材が得られることがわかった。

From the results shown in FIG. 8, repeated melting and solidification were observed at a melting point of about 33 ° C. and a freezing point of about 26 ° C. From this, it was found that the resin particles C-1 carrying disodium tetraborate function as a nuclear catalyst for sodium sulfate decahydrate.
Conventionally, disodium tetraborate has been known as a nuclide nuclide on which sodium sulfate decahydrate can grow epitaxially because of its similarity in crystal lattice size. However, since sodium borate crystals are difficult to dissolve and sodium sulfate hydrate is dissonantly melted to precipitate anhydrous sodium sulfate, stable repeated coagulation in a short time is difficult.
From the results in Table 7, by using resin particles carrying disodium tetraborate as a nucleating agent for heat storage, the melt of sodium sulfate becomes creamy and component separation is small, so that sulfate with high repeated coagulation stability It was found that a sodium hydrate-based heat storage material can be obtained.

The heat storage material of the present invention can suppress supercooling and has high repeated solidification stability, and is therefore used in various heat and cold insulation fields. In particular, it is repeated in a relatively short time such as cooling the CPU and battery of a smartphone. It can be suitably used for applications that require cooling and solidification.

Claims (13)

A heat storage nuclide agent comprising resin particles carrying a nuclide nuclide. The heat storage nucleating agent according to claim 1, wherein the volume average particle diameter of the resin particles is 0.05 μm or more and 1.0 μm or less. The heat storage nucleating agent according to any one of claims 1 to 2, wherein the resin particles include surface-basic amino-based resin particles. The heat storage nucleating agent according to claim 3, wherein the surface-basic amino resin particles are at least one of melamine resin particles, benzoguanamine resin particles, and urea resin particles. The heat storage nuclide according to any one of claims 1 to 4, wherein the nuclide is disodium hydrogen phosphate or disodium tetraborate. A heat storage material characterized by containing resin particles holding nuclide nuclides on the surface and salt hydrate. The heat storage material according to claim 6, wherein the difference (AB) between the true density A of the resin particles and the true density B of the salt hydrate is within ± 0.25 g / cm ³ . The heat storage material according to any one of claims 6 to 7, wherein the volume average particle diameter of the resin particles is 0.05 μm or more and 1.0 μm or less. The heat storage material according to any one of claims 6 to 8, wherein the resin particles include surface-basic amino-based resin particles. The heat storage material according to claim 9, wherein the surface-basic amino resin particles are at least one of melamine resin particles, benzoguanamine resin particles, and urea resin particles. The nuclide nuclide is disodium hydrogen phosphate or disodium tetraborate.
The heat storage material according to any one of claims 6 to 10, wherein the salt hydrate is sodium acetate trihydrate or sodium sulfate decahydrate. The heat storage material according to any one of claims 6 to 11, which can be repeatedly melted and solidified. A step of adding resin particles to a nucleating compound dissolved in a solvent, mixing and dispersing the mixture, and then pulverizing the dried product obtained by drying.
The step of adding the obtained ground product to the salt hydrate,
A method for producing a heat storage material, which comprises.

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