JP6682082B2 - Large particle size heat storage microcapsule and its manufacturing method - Google Patents

Description

  The present invention relates to a microcapsule having a size of 200 to 2000 μm, which can be easily produced, and can contain a PCM (phase change substance) heat storage substance at a high concentration, and a method for producing and using the same.

In order to obtain the energy saving effect by immersing the PCM heat storage microcapsules in the water storage tank in the ice heat storage air conditioning system, it is preferable that the submerged microcapsules have a 200 to 2000 micron size because water can flow around them and the heat transfer characteristics are good.

Although the use of heat storage microcapsules in the ice heat storage air conditioning system described above has a large energy saving effect, this system is still not widely used for large size, strong, leak-free, supercooling. This is because the suppressed heat storage microcapsules are not provided.

For leak-free microcapsules, conventionally, a method has been proposed in which the outer wall film is a melamine resin film, a nylon film, a polyurethane film, a cross-linked polymer film or the like, or a combination thereof to form a double film or a triple film.

When preparing large-sized microcapsules by any of these methods, there is a problem of droplet instability, and the problem of stable and mass production of tough microcapsules of 200 to 2000 micron size is Not resolved.

That is, it is difficult to stably maintain a large amount of large droplets without breaking them, and it is also difficult to solve the problem of coalescence of droplets when the viscosity of the outer wall monomer increases and the viscosity increases. It remains as an issue. Even if a large-sized microcapsule is prepared by these methods, there remains a problem to be solved in its strength.

In addition, by coating the outer wall of solid particles, a tough microcapsule preparation technology has been provided, but since there are no stable solid particles of 100 microns or more, a technology for providing microcapsules of a larger size is available. Not provided.

Therefore, several to several hundreds of various heat storage microcapsules of various sizes of 10 to 50 microns which can be stably prepared by the above-mentioned patent application technique are stably adhered to form a strong, leak-free, Techniques for forming microcapsules of 200 to 1000 micron size with suppressed cooling have been proposed, but they are not sufficient at present.

JP-A-4-82036 JP-A-5-163486 JP-A-7-213890 JP 2001-247855 A JP, 2009-19857, A JP, 2011-213750, A

   As described in Patent Document 5, when the cold heat storage microcapsules are immersed in the water storage tank of the ice storage air conditioning system, the effective size is 200 to 2000 microns in terms of handling and heat transfer characteristics. With respect to the cold heat storage microcapsules of 200 to 2000 micron size, which falls within this range, the preparation technology has not been completed for the above reason, which is a bottleneck for practical use and is a problem to be solved.

  The above problem is caused by impregnating a porous sphere particle having a large particle size of 200 to 2000 μm and having many cavities with a PCM heat storage substance, and forming a melamine film, an amide film, a urethane film or a urea film on the surface of the sphere particle alone or in combination. The problem can be solved by providing microcapsules coated with

The method for producing microcapsules according to the present invention is as follows.

  S. Kiyoyama, H .; Ueno, K .; Shiomori, Y .; Kawano and Y. Hatate, "Preparation of Cross-Linked Microcapsules Entrapping Inorganic Salt by In-situ Polymerization in (W / O / W) Emulsion Venouring Effort. 34, No. 1, pp. 36-42 (2001)), a first step of obtaining porous sphere particles having many cavities of 200 to 2000 μm size, and a material for coating the surface of the porous particles as a composite membrane of polyurea membrane and polyamide membrane. In this case, polyisocyanate and acid chloride are previously dissolved in the PCM heat storage organic medium, and the heat storage organic medium solution is impregnated into the porous particles obtained in the first step, thereby heat storage of 200 to 2000 μm size. The second step of obtaining spherical particles filled with an organic medium, and dispersing this particle group phase into a separately prepared aqueous phase in which polyamine is dissolved to make the pH of the aqueous phase neutral or weakly alkaline. Then, a third step of forming a polyurea resin wall from the inside by forming a polyamide resin coating on the surface of the spherical particles and then heating to 40 to 90 ° C., It is characterized by having.

The size and porosity of the microcapsules in the above-mentioned production method can be easily controlled by changing the operating conditions during the formation of the W ₁ / O / W ₂ emulsion in the first step.

3 is a scanning electron micrograph of the porous particles obtained in the first step of Example 1. 3 is a DSC measurement result of the PCM heat storage microcapsules prepared in Example 1.

The reagents used in the first step are as follows. The inner aqueous phase (W ₁ ) is composed of an aqueous phase in which salts such as sodium chloride and calcium chloride are dissolved. The oil phase (O) is composed of an oil-soluble dispersion stabilizer, a radical polymerization initiator, and a monomer containing an organic solvent. The external water phase (W ₂ ) is composed of an aqueous phase containing a water-soluble dispersion stabilizer. Examples of the oil-soluble dispersion stabilizer include polyglycerin condensed ricinoleic acid and polyoxyethylene lauryl ether. They may be used alone or in combination of two or more.

Azo compounds such as α, α-azobisisobutyronitrile and azobiscyclohexanecarbonitrile as radical polymerization initiators, and peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide and lauroyl peroxide. Can be illustrated. They may be used alone or in combination of two or more.

Monomers include monofunctional or crosslinkable monomers, styrene, acrylonitrile, chlorostyrene, styrene methylstyrene, ethylstyrene, methoxystyrene, nitrostyrene, aminostyrene, methyl methacrylate, methyl acrylate, acrylic acid. Ethyl, phenyl acrylate, cyclohexyl acrylate, vinyl acetate, vinyl formate, vinyl phenyl ether, vinyl methyl ether, vinyl cyclohexyl ether, divinylbenzene, ethylene glycol dimethacrylate, triethylene dimethacrylate, trimethylolpropane trimethacrylate, etc. Can be mentioned. They may be used alone or in combination of two or more.

As a water-soluble dispersion stabilizer in the external water phase, styrene-maleic anhydride copolymer hydrolyzate, sodium dodecylbenzenesulfonate, lecithin, gelatin, gum arabic, casein, dextrin, pectin, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl Ether, polyacrylic acid, polyoxyethylene-added tri- or distyryl phenyl ether, polyoxyethylene-added alcohol ether, polyoxyethylene-added sorbitan oleate and other tween surfactants, sorbitan oleate, etc. Spun surfactants, polyacrylic acid salts, cellulose derivatives (alkali metal salts of carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydrid Roxypropylethylcellulose, methylcellulose, ethylcellulose), polyhydric alcohols (glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,4-butanediol, maltitol, Xylitol etc.)). The water-soluble dispersion stabilizer is used alone or in combination of two or more.

The reagents used in the second step are a PCM heat storage organic substance medium, a chloride-based polymerizable reactive substance, and a polymerizable reactive substance having an isocyanate group, and are as follows.

  As the PCM heat storage organic substance medium used in the second step, paraffin wax, fatty acid, fatty acid ester and the like are used at least alone or in combination of two or more kinds.

As the chloride-based polymerizable reactive substance used in the second step, malonyl dichloride, succinic acid chloride, glutar dichloride, adipoyl dichloride, sebacyl dichloride, fumarine chloride, fumaryl chloride, itaconyl chloride, terephthalic acid chloride, trimesoyl chloride. Etc. They may be used alone or in combination of two or more.

As the polymerizable reactant having an isocyanate group used in the second step, phenyl isocyanate, tolylene isocyanate, phenylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate and the like are used. They may be used alone or in combination of two or more. This also includes an adduct of toluidine isocyanate and hexanetriol such as Desmodur L.

As the amine-based polymerizable reactive substance newly used in the third step, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, 2-methylpiperazine, diethylenetriamine, triethylenetetramine. Etc. They may be used alone or in combination of two or more.

  Hereinafter, each embodiment of the present invention will be described in accordance with each step of producing microcapsules of 200 to 2000 μm containing a PCM heat storage material according to the present invention, and the features and applications of the obtained microcapsules.

(First step) The preparation of microcapsules having a large particle size and having a porous structure is as follows. An organic compound consisting of the cross-linking agent monomer divinylbenzene and trimethylolpropane trimethacrylate with the removal of the polymerization inhibitor, an oil-soluble surfactant polyglycerin condensed ricinoleic acid, a radical polymerization initiator azobisvaleronitrile and an organic solvent toluene. An aqueous sodium chloride solution (W ₁ phase) is added to the phase (O phase) and mixed vigorously to form a W ₁ / O emulsion. This W ₁ / O emulsion is added to the external water phase W ₂ in which the water-soluble dispersion stabilizer polyvinyl alcohol prepared in advance is added and mixed by stirring to form a W ₁ / O / W ₂ emulsion. Then, the polymerization reaction is completed in a nitrogen atmosphere. After completion of the polymerization reaction, the prepared microcapsules are filtered through a 100 μm mesh, washed with distilled water, vacuum dried, and collected.

(Second step) Tetradecane, which is a PCM solvent in which terephthalic acid chloride and diphenylmethane diisocyanate are dissolved, is prepared. In advance to this organic liquid, the oil-soluble surfactant polyglycerin condensed ricinoleic acid is added, and the above-mentioned porous microcapsules obtained above are added and stirred, and in some cases, degassing by repeating vacuum operation, The organic liquid is well adapted to the inside of the microcapsules, and the microcapsules are filled with the organic liquid.

(Third step) In order to form a polyamide film on the outer shell of the microcapsule, an aqueous solution in which hexamethylenediamine is dissolved is prepared. To this aqueous solution, polyvinyl alcohol is added as a dispersion stabilizer, and the microcapsules filled with the above-mentioned organic liquid are charged and stirred and mixed while keeping the liquid weakly alkaline, and the outer wall of the microcapsules is coated with a polyamide film. Thereafter, the reaction temperature is raised to form a polyurea film on the inner wall of the microcapsule, whereby a strong, leakproof microcapsule containing a PCM heat storage medium can be obtained.

  The microcapsules are spherical particles having a porous structure, and the particle size can be controlled mainly by the salt concentration in the inner aqueous phase in the first step, and the higher the degree of circle, the larger the particle size. The microcapsule strength can be controlled by the concentrations of the chloride-based polymerizable reactive substance and the isocyanate group-containing polymerizable reactive substance in the second step. The higher the concentration, the higher the microcapsule strength.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(First step) Cross-linking monomer divinylbenzene from which the polymerization inhibitor was removed, 9.8 g, trimethylolpropane trimethacrylate, 25.5 g, oil-soluble surfactant, polyglycerin condensed ricinoleic acid, 4.5 g, polymerization initiator An organic phase composed of 0.5 g of azobisdimethylvaleronitrile and 4.5 g of an organic solvent toluene was prepared. Under ice cooling, 5.0 g of sodium chloride 6.0 mol / liter aqueous solution was added to this organic phase, and the mixture was stirred and mixed with a homogenizer at 8000 rpm for 10 minutes to prepare a (W ₁ / O) emulsion. This (W ₁ / O) emulsion was added to 450 g of an external water phase (W ₂ phase) in which 9.0 g of partially saponified polyvinyl alcohol and 1.1 g of sodium dodecyl sulfate were dissolved, and the mixture was stirred and mixed at 250 rpm to obtain (W ₁ / O). / _{W 2)} to form an emulsion. Then, the polymerization reaction was allowed to proceed at 250 rpm and 70 ° C. in a nitrogen atmosphere, and the polymerization was completed in 5 hours. The prepared microcapsules were filtered with a 100 μm mesh, washed with distilled water and vacuum dried, and then the porous microcapsules were collected. The yield was 86%.

(Second step) 50 g of a tetradecane solution which is a PCM solvent in which 0.5 g of terephthalic acid chloride and 0.5 g of diphenylmethane diisocyanate are dissolved is prepared. To this organic liquid, 1 g of oil-soluble surfactant polyglycerin-condensed ricinoleic acid was added, and 5.0 g of porous microcapsules with many cavities obtained by the above method were added and stirred to sufficiently adapt the microcapsules to the solution. It was The gas remaining in the microcapsules was removed by degassing this system with a vacuum pump, and the organic liquid was sufficiently taken into the microcapsules and kept in a 100 μm mesh.

(Third step) In order to form a polyamide film on the outer shell of the microcapsule, 200 g of an aqueous solution in which 5.3 g of hexamethylenediamine was dissolved was prepared. To this aqueous solution, 2 g of polyvinyl alcohol was added as a dispersion stabilizer in order to stably disperse the microcapsule particles. To this solution containing diamine and PVA, 5 g of the above-mentioned microcapsules in a 100 μm mesh was put, and while stirring and mixing, the liquid was kept weakly alkaline, and the outer wall of the microcapsules was coated with a polyamide film. Thereafter, the reaction temperature was raised to 70 ° C. and maintained for 3 hours, and a polyurea film was formed on the inner wall of the microcapsule to obtain a robust and leak-free microcapsule containing a PCM heat storage medium inside.

(First step) Cross-linking monomer divinylbenzene from which the polymerization inhibitor was removed, 9.8 g, trimethylolpropane trimethacrylate, 25.5 g, oil-soluble surfactant, polyglycerin condensed ricinoleic acid, 4.5 g, polymerization initiator An organic phase composed of 0.5 g of azobisdimethylvaleronitrile and 4.5 g of an organic solvent toluene was prepared. Under ice cooling, 5.0 g of sodium chloride 6.0 mol / liter aqueous solution was added to this organic phase, and the mixture was stirred and mixed with a homogenizer at 8000 rpm for 10 minutes to prepare a (W ₁ / O) emulsion. This (W ₁ / O) emulsion was added to 450 g of an external water phase (W ₂ phase) in which 9.0 g of partially saponified polyvinyl alcohol and 1.1 g of sodium dodecyl sulfate were dissolved, and the mixture was stirred and mixed at 250 rpm to obtain (W ₁ / O). / _{W 2)} to form an emulsion. Then, the polymerization reaction was allowed to proceed at 250 rpm and 70 ° C. in a nitrogen atmosphere, and the polymerization was completed in 5 hours. The prepared microcapsules were filtered with a 100 μm mesh, washed with distilled water and vacuum dried, and then the porous microcapsules were collected. The yield was 90%.

(Second step) 50 g of a tetradecane solution which is a PCM solvent in which 0.5 g of terephthalic acid chloride and 1 g of a 3: 1 molar adduct of hexamethylene diisocyanate and hexanetriol are dissolved is prepared. To this organic liquid, 1 g of oil-soluble surfactant polyglycerin-condensed ricinoleic acid was added, and 5.0 g of porous microcapsules with many cavities obtained by the above method were added and stirred to sufficiently adapt the microcapsules to the solution. It was The gas remaining in the microcapsules was removed by degassing this system with a vacuum pump, and the organic liquid was sufficiently taken into the microcapsules and kept in a 100 μm mesh.

(Third step) In order to form a polyamide film on the outer shell of the microcapsule, 200 g of an aqueous solution in which 5.3 g of hexamethylenediamine was dissolved was prepared. To this aqueous solution, 2 g of polyvinyl alcohol was added as a dispersion stabilizer in order to stably disperse the microcapsule particles. To this solution containing diamine and PVA, 5 g of the above-mentioned microcapsules in a 100 μm mesh was put, and while stirring and mixing, the liquid was kept weakly alkaline, and the outer wall of the microcapsules was coated with a polyamide film. Thereafter, the reaction temperature was raised to 70 ° C. and maintained for 3 hours, and a polyurethane film was formed on the inner wall of the microcapsule to obtain a robust, leak-free microcapsule containing a PCM heat storage medium inside.

(First step) 30.5 g of trimethylolpropane trimethacrylate, a cross-linking monomer from which a polymerization inhibitor has been removed, 4.5 g of an oil-soluble surfactant polyglycerin-condensed ricinoleic acid, a polymerization initiator azobisdimethylvaleronitrile 0 An organic phase composed of 0.5 g and an organic solvent of benzene 4.5 g was prepared. Under ice cooling, 5.0 g of sodium chloride 6.0 mol / liter aqueous solution was added to this organic phase, and the mixture was stirred and mixed with a homogenizer at 8000 rpm for 10 minutes to prepare a (W ₁ / O) emulsion. This (W ₁ / O) emulsion was added to 450 g of an external water phase (W ₂ phase) in which 9.0 g of partially saponified polyvinyl alcohol and 1.1 g of sodium dodecyl sulfate were dissolved, and the mixture was stirred and mixed at 250 rpm to obtain (W ₁ / O). / _{W 2)} to form an emulsion. Then, the polymerization reaction was allowed to proceed at 250 rpm and 70 ° C. in a nitrogen atmosphere, and the polymerization was completed in 5 hours. The prepared microcapsules were filtered with a 100 μm mesh, washed with distilled water and vacuum dried, and then the porous microcapsules were collected. The yield was 92%.

(Second step) 50 g of a tetradecane solution, which is a PCM solvent, in which 0.5 g of terephthalic acid chloride, 0.5 g of diphenylmethane diisocyanate, and 1 g of a 3: 1 molar adduct of hexamethylene diisocyanate and hexanetriol are dissolved is prepared. To this organic liquid, 1 g of oil-soluble surfactant polyglycerin condensed ricinoleic acid was added, and 5.0 g of the porous microcapsules obtained by the above-mentioned method was added and stirred to sufficiently adapt the microcapsules to the solution. The gas remaining in the microcapsules was removed by degassing this system with a vacuum pump, and the organic liquid was sufficiently taken into the microcapsules and kept in a 100 μm mesh.

(Third step) In order to form a polyamide film on the outer shell of the microcapsule, 200 g of an aqueous solution in which 5.3 g of hexamethylenediamine was dissolved was prepared. To this aqueous solution, 2 g of polyvinyl alcohol was added as a dispersion stabilizer in order to stably disperse the microcapsule particles. To this solution containing diamine and PVA, 5 g of the above-mentioned microcapsules in a 100 μm mesh was put, and while stirring and mixing, the liquid was kept weakly alkaline, and the outer wall of the microcapsules was coated with a polyamide film. Then, the reaction temperature was raised to 70 ° C. and maintained for 3 hours, and a composite film of polyurethane and polyurea was formed on the inner wall of the microcapsule to obtain a robust and leak-free microcapsule containing a PCM heat storage medium inside.

Claims (2)

A heat storage microcapsule having a large particle size, characterized in that a porous PCM having a size of 200 to 2000 μm is filled with a PCM medium, a polyurea film is used as an inner wall, and a polyamide film is used as an outer film. An aqueous salt solution (W ₁ phase) is added to an organic phase (O phase) consisting of a monomer , an oil-soluble surfactant, an organic solvent and a radical polymerization initiator to form a (W ₁ / O) emulsion, which is in addition to the external aqueous phase obtained by dissolving a water-soluble dispersion stabilizer _{(W 2), (W 1} / O / W 2) to form an emulsion, it was prepared to complete the polymerization reaction by heating, 200 to 2000 A step of forming porous particles of a size and a step of impregnating the porous particles obtained in the above-mentioned step with a PCM heat storage organic medium solution in which polyisocyanate and acid chloride are dissolved to form PCM heat storage medium containing particles; By dispersing the PCM heat storage medium-containing particles obtained in the above-described step in the polyamine-dissolved water phase to make the pH of the water phase neutral or weakly alkaline, a polyamide resin film is formed on the surface of the PCM heat storage medium-containing particles. To Made was, then, by raising the temperature, the preparation of large grain size of the heat storage microcapsules; and a resin-coated PCM heat storage particles forming step of forming a polyurea resin wall from the inside.

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