JP2001279233A - Thermal storage material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermal storage material having effects on leveling room temperature not only in the winter or summer season but also throughout a year and having a higher thermal storage efficiency than that of a conventional product even when the use as a thermal storage material for houses is supposed. SOLUTION: This thermal storage material is characterized as dispersing a thermal storage substance for low temperatures consisting essentially of a compound capable of freely carrying out the phase transition at >=15 and <=20 deg.C and a thermal storage substance consisting essentially of a compound capable of freely carrying out the phase transition at >=24 and <=34 deg.C in the same substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage material, and more particularly to a heat storage material suitable for residential use.

[0002]

2. Description of the Related Art In recent years, it has been demanded to save energy by using natural heat energy such as sunlight for heating a house, and as a specific application example, a heat storage material is used for a house building material. As a result, attempts have been made to equalize the indoor temperature in winter and summer. At that time, as a method of using the sensible heat of a fluid such as water as a necessary heat storage medium or heat transfer medium, or a method of obtaining higher thermal efficiency, a latent heat storage material is microencapsulated and suspended in water. A way to make it happen has been considered.

Conventionally, this type of heat storage system, or
As a microcapsule used in a heat transfer system, a microcapsule provided with a capsule wall made of a melamine resin film around a core substance mainly composed of a latent heat storage material such as an aliphatic hydrocarbon (Japanese Patent Laid-Open No. 5-163486) JP-A-8-2
(Japanese Patent Application Laid-Open No. Sho 62-225241) and a core material having a latent heat storage material such as a hydrate of an inorganic salt as a main component and a capsule wall made of a styrene resin film around the core material.
Is known. However, the phase transition temperature of the latent heat storage material used as the core material of the heat storage microcapsules exemplified in the above literature is 5 ° C. or less or 28 ° C. or more, and the indoor temperature of a general house (winter: 10 to 10 ° C.) 28
Considering that the heat storage microcapsules are used for residential building materials, phase transition does not occur and only the effect of sensible heat is obtained, resulting in extremely poor heat storage efficiency. ing. Therefore, a heat storage material having a sufficiently high heat storage efficiency in both winter and summer is demanded as a residential building material that exhibits an effect of leveling the room temperature throughout the year.

[0004]

SUMMARY OF THE INVENTION The object of the present invention has been made in view of the above-mentioned prior art, and is intended for use as a heat storage material for a house in winter and summer.
An object of the present invention is to provide a heat storage material having higher heat storage efficiency than conventional products.

[0005]

Means for Solving the Problems To solve the above-mentioned problems, the present inventors firstly developed a low-temperature heat storage material exhibiting a heat storage effect in a winter house and a high-temperature heat storage material exhibiting a heat storage effect in a summer house. Attention was paid to a heat storage material in which substances are separately dispersed in the same base material.

Next, in the test room where the heat storage material is arranged,
The average temperature in Tokyo in January (approximately 5
° C; see the 1998 scientific chronology)
When a test room with heat storage material was prepared, the room temperature was controlled to 20 to 23 ° C using auxiliary heating for 16 hours, and the remaining 8 hours were allowed to cool without using auxiliary heating equipment The room temperature change was observed, and the relationship with the heat storage material phase transition temperature was investigated. In the same way, assuming the use of summer housing,
A test room equipped with heat storage materials was built in an environment that can reproduce the average maximum temperature in Tokyo in August (approximately 31 ° C; see the 1998 science chronological table).
The temperature was controlled so as to be about 26 ° C., and for the remaining 4 hours, the room temperature change was observed when the apparatus was allowed to stand without using an auxiliary heating device, and the relationship with the heat storage material phase transition temperature was investigated.

As a result of the above research, it has been found that, in winter and summer residences, the heat storage effect of a compound capable of phase transition can be effectively utilized,
If the temperature change in the room is small and it is desired to level the temperature, it is necessary to control the phase transition temperatures of the low-temperature heat storage material and the high-temperature heat storage material in an extremely narrow range,
The present invention has been made.

The heat storage material of the present invention has a low-temperature heat storage material mainly composed of a compound capable of phase transition at 15 ° C. or more and 20 ° C. or less, and a compound mainly composed of a compound capable of phase transition at 24 ° C. or more and 34 ° C. or less. The high-temperature storage material is dispersed in the same base material.

Further, in order to prevent the phase change temperature from changing due to the mixture of the low-temperature heat storage material and the high-temperature heat storage material in the same base material, and to improve the thermal efficiency by uniformly dispersing the heat storage material. It is preferable that the low-temperature heat storage material and the high-temperature heat storage material are separately encapsulated on the outer wall of a thermoplastic resin obtained by radical addition polymerization to form microcapsule particles.

The phase-changeable compound (hereinafter referred to as "latent heat storage material") constituting the low-temperature heat storage material and the high-temperature heat storage material is used for storing heat by utilizing latent heat accompanying the phase transition, and is used for residential purposes. In order to demonstrate high heat storage efficiency in
A low-temperature heat storage material having a phase transition temperature of 15 to 20 ° C., and a high-temperature heat storage material having a phase transition temperature of 24 to 34 ° C.
° C is used. Such heat storage materials are roughly classified into organic compounds and inorganic compounds.

Examples of the organic compound include aliphatic hydrocarbons, aromatic hydrocarbons, fatty acids, alcohols, and the like. The type of the organic compound is not limited, but it is particularly preferable to use aliphatic hydrocarbons. When used alone, hexadecane is used. When used alone as a high-temperature storage material, octadecane is used.
Other aliphatic hydrocarbons that can be used as a mixture include pentadecane, hexadecane, heptadecane, octadecane, nonadecane, icosane, docosane and the like. These hydrocarbons have a phase transition temperature of 15 to 20 ° C. or 2
It is possible to use a mixture of two or more hydrocarbons so that the temperature is 4 to 34 ° C.

Examples of the inorganic compound include hydrates of inorganic salts, and the types thereof are not limited. Examples thereof include calcium chloride hexahydrate, sodium carbonate decahydrate, and sodium sulfate decahydrate. And a phase transition temperature of 15 to
It is possible to use a mixture of two or more inorganic hydrates at a temperature of 20 ° C or 24 to 34 ° C. The hydrates of these inorganic salts have a phase transition temperature of 25 ° C. or more in a simple substance, but the phase transition temperature is adjusted to 15 to 20 ° C. by adding an inorganic salt such as sodium chloride or potassium chloride. Can be. Carbon, metal powder, alcohol, or the like may be added to the heat storage material for the purpose of adjusting thermal conductivity and specific gravity.

In the present invention, the thermoplastic resin for microencapsulating the heat storage material for low temperature and the heat storage material for high temperature is not particularly limited, and examples thereof include poly (meth) acrylate, polystyrene derivative, polyvinyl acetate derivative, and melamine resin. However, in order to efficiently produce a product that has a small amount of residual monomer in the product and is safe even when used as a house building material, it is necessary to use an in-radical addition polymerization mechanism.
It is preferable to use a thermoplastic resin that can be synthesized by a situ polymerization method. In particular, as the thermoplastic resin, a general-purpose resin synthesized from a monomer having high radical polymerization activity such as poly (meth) acrylate, polystyrene derivative, or polyvinyl acetate derivative is preferably used, and more preferably poly (meth) acrylate. Acrylate and polystyrene derivatives. These are used alone or as a copolymer.

The (meth) acrylate monomer used in the polymerization of the above-mentioned poly (meth) acrylate is not particularly restricted but includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate and butyl (meth) acrylate. A) acrylate, cumyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, alkyl (meth) acrylate such as isononyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate Containing polar groups such as (meta)
Acrylates can be mentioned, and these can be used alone or in combination of two or more.

The styrene derivative monomer used for the polymerization of the above-mentioned polystyrene derivative is not particularly restricted but includes, for example, styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene and the like. More than one species can be used in combination.

Other monomers used for the polymerization of the thermoplastic resin are not particularly limited, but include vinyl acetate,
Examples thereof include vinyl esters such as vinyl propionate, unsaturated nitriles such as acrylonitrile and methacrylonitrile, acrylic acid, and methacrylic acid. These can be used alone or in combination of two or more.

In order to improve the mechanical strength of the capsule wall, a polyfunctional monomer may be added to the thermoplastic resin, if necessary. Although the type of the polyfunctional monomer is not particularly limited, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth)
Acrylate, 1,6-hexanediol di (meth) acrylate, di (meth) acrylates such as trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) Tri (meth) acrylates such as acrylate and pentaerythritol tri (meth) acrylate; Other polyfunctional monomers include (meth) acrylate compounds such as pentaerythritol tetra (meth) acrylate and dipentaeristol hexa (meth) acrylate, diallyl phthalate, diallyl maleate, diallyl fumarate, diallyl succinate And divinyl compounds such as triallyl isocyanurate and divinyl compounds such as divinylbenzene and butadiene. These can be used alone or in combination of two or more.

The method for producing the microcapsules containing the heat storage material is not particularly limited. In general, for example, a mixture of the heat storage material and the radical polymerizable monomer used for forming the capsule wall is emulsified and suspended in water, and the oil is mixed. It is obtained by radical polymerization of the monomer in the droplet.

The average particle size of the microcapsules in the slurry containing the microcapsules obtained by the above polymerization is not particularly limited, but the preferred particle size differs depending on the method of use. For example, when used as a slurry, separation of water from microcapsules tends to occur as the size increases,
If the size is too small, the strength of the capsule will decrease.
10 μm is appropriate. On the other hand, when the microcapsules are dried and used as a powder, the thickness is preferably 10 to 3000 μm from the viewpoint of the operability of the drying step.

In the heat storage material of the present invention, the microcapsules (hereinafter referred to as low-temperature heat storage microcapsules and high-temperature heat storage microcapsules) containing the low-temperature heat storage material and the high-temperature heat storage material, respectively, obtained by the above method are the same. It is completed by dispersing in a substrate. The weight ratio of the low-temperature heat storage microcapsules dispersed in the base material and the high-temperature heat storage microcapsules is not particularly limited, but if either one of the weight ratios is too large, the heat storage effect cannot be exhibited throughout the year. Therefore, the ratio of the low-temperature heat storage microcapsules to the high-temperature heat storage microcapsules is 10/90 to
A 90/10 weight ratio is preferred.

The heat storage microcapsules are used as a heat storage material by being encapsulated in a slurry state in a container or added as a composition to another substance. For example, a heat storage microcapsule slurry and cement are mixed and dried to be used as a heat storage plate. At this time, the slurry may be added with an antifreezing agent such as ethylene glycol, polyethylene glycol and various inorganic salts, a preservative, a thickener, a pigment, a preservative, and a dispersant, if necessary. . Further, the heat storage microcapsules may be separated as a powder from the slurry and shaped by various molding methods, or may be added as a composition to another substance and used as a heat storage material.

[0022]

Hereinafter, embodiments of the present invention will be described.
It is not limited to the following example. (Preparation of heat storage microcapsules) Based on the composition shown in Table 1, low-temperature and high-temperature heat storage microcapsules were prepared in the following procedure. Examples 1 to 3 and Comparative Examples 1 to 3 A predetermined amount of an aliphatic hydrocarbon melted at 50 ° C, a monomer for forming a capsule wall, and an initiator were mixed and stirred, and then ion-exchanged water (total used amount) 60% by weight), a dispersant was added and stirred to prepare an emulsion monomer liquid. On the other hand, the remaining ion-exchanged water was charged into the polymerization vessel, and stirring was started. After depressurizing the inside of the polymerization vessel and deoxidizing the inside of the vessel, the pressure was returned to atmospheric pressure with nitrogen, and the inside was set to a nitrogen atmosphere, and then the emulsified monomer liquid was added all at once. 8 polymerization tanks
The temperature was raised to 0 ° C. to initiate polymerization. The polymerization was completed in 30 minutes, and after an aging period of 1 hour, the polymerization tank was cooled to room temperature. A slurry containing microcapsules having a solid content of about 50% by weight and an average particle size of about 3 μm was obtained.
The time required for the polymerization step from the start of the polymerization to the completion of the aging from the start of the polymerization was about 1.5 hours.

Example 4 A 40% by weight aqueous solution of formaldehyde was added to a predetermined amount of melamine powder to adjust the pH to 8. Then about 70 ° C
Then, the mixture was aged for 1 hour to obtain a melamine resin prepolymer aqueous solution. On the other hand, a sodium salt of styrene-maleic anhydride copolymer adjusted to pH 4 (hereinafter PSM)
To a 4% by weight aqueous solution of Na) was added an aliphatic hydrocarbon melted at 40 ° C. with stirring to obtain an emulsified suspension. The prepolymer aqueous solution of the melamine resin was added to the emulsified suspension at a time, and the polymerization vessel was heated to 70 ° C. to initiate polymerization. The polymerization was completed in 2 hours, and after an aging period of 1 hour, the polymerization tank was cooled to room temperature.
A slurry containing microcapsules having a solid content of about 50% by weight and an average particle size of about 3 μm was obtained. The time required for the polymerization step from the start of the polymerization of the melamine prepolymer to the completion of aging of the final product was about 4.0 hours.

(Preparation of heat storage building material) Based on the composition shown in Table 2, a heat storage building material was obtained by the following procedure. Examples 5 to 7, Comparative Examples 4 to 8 A predetermined amount of cement, a low-temperature heat storage microcapsule and a high-temperature heat storage microcapsule slurry were mixed, and the mixture was heated to 70 ° C
To prepare a heat storage plate having a thickness of 1 cm.

[Evaluation] Using the obtained heat storage microcapsules, the amount of residual monomer, phase transition temperature, and heat of fusion were evaluated by a core method in which the heat storage effect was evaluated using heat storage building materials. The results are shown in Tables 1 and 2. (Amount of residual monomer) Using gas chromatography,
The amount of residual monomer in the slurry was measured. As a result, the amount of the residual monomer with respect to all the monomers used for the polymerization was shown by weight fraction. (Phase transition temperature and heat of fusion) Differential scanning calorimeter (DSC62
00, manufactured by Seiko Instruments Inc.), and the phase transition temperature and heat of fusion of the slurry were measured. Measurement temperature range is 0
-50 ° C, the temperature rising rate was 2 ° C / min, and the temperature at which the endothermic amount showed a peak was taken as the phase transition temperature. Produced a test chamber (heat accumulation effect) contents using assumed air conditioning possible winter house product 1 m ^3, it paved the heat storage plate to the inner wall. The test room was set in a constant temperature room set at an ambient temperature of 8 ° C., and first, the atmospheric temperature in the test room was kept at 22 ° C. for 16 hours. Thereafter, the air-conditioning was stopped and the system was left for 8 hours, and the temperature in the test room was measured. The heat storage effect was determined as follows based on the temperature drop width of the test room temperature. ○: Temperature drop of less than 10 ° C (indoor temperature of 12 ° C or more) ×: Temperature drop of 10 ° C or more (indoor temperature of less than 12 ° C) Assumed use of summer house A test room with an internal volume of 1m3 capable of air conditioning is manufactured. Then, the heat storage plate was spread on the inner wall. The test room was set in a constant temperature room set at an ambient temperature of 35 ° C. First, the atmospheric temperature in the test room was kept at 23 ° C. for 20 hours. After that, the air conditioning was stopped and left for 4 hours, and the temperature in the test room was measured. The heat storage effect was determined in the following manner based on the temperature rise in the test room. ○ mark: temperature rise of less than 5 ° C (room temperature less than 28 ° C) × mark: temperature rise of 5 ° C or more (room temperature 28 ° C or more)

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the heat storage material of the present invention, two kinds of heat storage materials in which the phase change of the heat storage material occurs at 15 ° C. or more and 20 ° C. or less and 24 ° C. or more and 34 ° C. or less are dispersed in the same base material. Assuming that the material is used as a heat storage material for a house, it has a heat storage effect not only in winter but also in summer, and has an effect of leveling the room temperature throughout the year. Further, since the capsule wall mainly composed of a thermoplastic resin obtained by radical polymerization is formed, the capsule wall is excellent in productivity, can be manufactured at low cost, and no harmful substance for human body remains in the product. Taking advantage of the above characteristics, it is suitably used for residential applications.

Claims (3)

[Claims] 1. A low-temperature heat storage material mainly composed of a compound capable of phase transition at 15 ° C. or more and 20 ° C. or less, and a high-temperature heat storage material mainly composed of a compound capable of phase change at 24 ° C. or more and 34 ° C. or less. A heat storage material characterized by being dispersed in the same base material. 2. The heat storage material for low temperature and the heat storage material for high temperature are microcapsules separately encapsulated by an outer wall of a thermoplastic resin obtained by radical addition polymerization. Heat storage material. 3. The heat storage material according to claim 2, wherein the thermoplastic resin obtained by radical addition polymerization is a poly (meth) acrylate or a polystyrene derivative.