JP5141156B2 - Method of dispersing microencapsulated phase change material in fluorine-based solvent, dispersion, and coolant for fuel cell stack - Google Patents

Description

  The present invention relates to a method for dispersing a microencapsulated water-soluble phase change material in a perfluorocarbon solvent, the dispersion, and a coolant for a fuel cell stack. More specifically, the present invention relates to a method of dispersing a microencapsulated phase change material, which is normally difficult to highly disperse in a fluorinated solvent, into a perfluorocarbon solvent, a dispersion dispersed by the method, and a fuel cell stack coolant. In particular, the present invention relates to an excellent fuel cell stack coolant having high insulation and sufficient cooling performance as a heat / cooling medium in the vicinity of the operating temperature of a fuel cell or the like.

  A stack of polymer electrolyte fuel cells is a laminated structure of a plurality of unit cells, and a cooling plate for cooling the stack (unit cell) is provided for each sub-stack composed of several unit cells. Yes. A coolant passage is formed in the cooling plate, and the stack is cooled by the coolant flowing through the coolant passage. In this way, the coolant of the fuel cell circulates within the stack that is generating power, that is, between the sub-stacks, so that the power generation efficiency is reduced due to leakage to the outside of the stack and the resistance of the coolant. High insulation performance is required to prevent (reduction). In order to satisfy these requirements for ensuring insulation performance and ensuring cooling efficiency, pure water has been used as a coolant in the prior art. In addition to these requirements, the fuel cell stack coolant is also required to have rust prevention properties in order to maintain the product life of the cooling plate. In general, this requirement has been addressed by using a stainless material having a high rust prevention property for the cooling plate.

  However, such a conventional countermeasure can be effective for a so-called fixed type, installation type medium / large-sized fuel cell, and always-on type fuel cell, for example, a fuel cell mounted on a vehicle. It was not necessarily effective for non-installation type small fuel cells and intermittent operation type fuel cells.

  For example, in the case of an intermittent operation type fuel cell and a non-installation type fuel cell, the coolant is lowered to the ambient temperature when not in operation, so that it is required to have antifreezing properties under conditions where the ambient temperature is below freezing point. This is because the cooling circuit including the cooling plate may be damaged when the cooling liquid freezes. In addition, when the cooling circuit is damaged, the fuel cell may not fully perform its function.

  Here, when antifreezing is taken into consideration, for example, a cooling liquid for cooling an internal combustion engine may be used as the antifreezing cooling liquid. However, since the coolant for cooling the internal combustion engine is used in a portion where electricity is not essentially generated, the resistance to electrical conductivity is not taken into consideration and the electrical conductivity is extremely high. On the other hand, since electricity flows through the cooling pipe of the fuel cell stack, if the electrical conductivity of the coolant is high, electricity generated in the fuel cell flows to the coolant and loses electricity. Therefore, it is not suitable as a coolant for cooling the fuel cell stack.

  Further, in the case of a non-installation type fuel cell mounted on a vehicle or the like, weight reduction of the fuel cell system including the cooling circuit is an important overcoming problem. Therefore, from the viewpoint of weight reduction, it is expected that light metals having high thermal conductivity such as aluminum materials will be used for cooling plates, heat exchangers and the like in the future. These light metals generally do not have as high anti-rust properties as stainless steel materials, and therefore the cooling liquid itself is required to have anti-rust properties.

  Accordingly, a cooling liquid and a heat transfer medium in which microcapsule particles containing a water-soluble phase change substance are dispersed in a non-aqueous solvent such as a fluorinated solvent have been developed.

  Incidentally, a method for dispersing phase-change material particles microencapsulated in a fluorine-based solvent is disclosed in Patent Document 1 below. In Patent Document 1, barium hydroxide octahydrate (melting point: 78 ° C.) particles as a phase change substance are dispersed in fluorine oil (perfluorocarbon), a silane coupling agent is added to the dispersion, and the silane coupling agent is inorganic. After adsorbing on the interface of the barium hydroxide octahydrate particles of the phase change material, which is a particle, the temperature of the dispersion is set to about 55 ° C. to polymerize the silane coupling agent at the phase change material particle interface. A dispersion of a phase change material microencapsulated in a fluorocarbon solvent is obtained. Further, in Patent Document 1, although not described in the examples, as a specific example of the microencapsulation component, a fluorine monomer having a double bond dissolved in fluorine oil (perfluorocarbon) as a fluorine solvent, phase change The monomer which has an adsorptivity to the inorganic particle which is a material is illustrated.

  Further, in Patent Document 2 below, barium hydroxide octahydrate (melting point: 78 ° C.) as a phase change substance, perfluorocarbon (trade name “Fluorinert FC3255”, manufactured by Sumitomo 3M) and fluorine-based emulsifier (product) After preparing an emulsified dispersion using a high-pressure emulsifier at a temperature equal to or higher than the melting point of the phase change material (85 ° C.), the name “Futgent 150” (manufactured by Neos), styrene monomer as a microencapsulating agent, divinyl Benzene monomer and polymerization initiator 4,4-azobis-4-cyanovaleric acid (trade name “AVCA”, manufactured by Otsuka Chemical Co., Ltd.) are added under stirring of the dispersion, and vinyl is added at the interface of the phase change material particles. A monomer is polymerized to obtain a dispersion of a phase change material microencapsulated in a fluorinated solvent. Further, in Patent Document 2, in order to disperse microencapsulated phase change material particles dispersed in a fluorinated solvent in a water-soluble solvent, water is added to the dispersion to form a microencapsulated phase change material. Microcapsules dispersed in a water-soluble solvent by precipitating the particles, filtering the precipitated particles as a solid, and redispersing the solid phase change material particles in water in which the emulsifier is dissolved Phase change material particles are obtained.

JP 2005-203148 A JP 2007-31597 A

  In the case of the method of dispersing phase change material particles microencapsulated in a fluorine-based solvent disclosed in Patent Document 1, the total amount of the microencapsulating agent is not adsorbed on the inorganic particle interface that is the phase change material. In addition, there is a problem in that micelles are formed in a fluorinated solvent and a large amount of microencapsulated particles that do not encapsulate phase change substances are contained, and phase change substance particles whose surface is covered with a surfactant However, the encapsulating agent is weakly adsorbed and a microencapsulated wall having sufficient strength cannot be formed. Furthermore, the types of vinyl monomers that are soluble in fluorine-based solvents are very limited, and it is difficult to select monomers that can be polymerized with sufficient strength as a microencapsulating agent that has adsorptivity to selected phase change materials. It also has the problem of being.

  In the case of the method of dispersing phase change material particles microencapsulated in a fluorine-based solvent disclosed in Patent Document 2, the total amount of the microencapsulating agent is at the phase change material interface as in Patent Document 1. It has the problem of forming micelles in a fluorinated solvent rather than adsorbing and containing many microencapsulated particles that do not encapsulate phase change materials, and the phase change whose surface is covered with a surfactant. The adsorption of the encapsulating agent to the material particles is weak, and there is a problem that a microencapsulated wall having sufficient strength cannot be formed. Furthermore, in the method of dispersing in a water-soluble solvent, since the solvent is separated by filtration, the productivity is poor, and in a state where the solvent is removed, the microencapsulated phase change material particles are combined, After re-dispersion, the phase change material particles have a large particle size, and some phase change material particles settle.

  The present invention has been made in view of the circumstances as described above, and the microencapsulated water solution has sufficient strength of the microencapsulation wall covering the water-soluble phase change material, and the sedimentation of the water-soluble phase change material particles is small. An object of the present invention is to provide a method for dispersing a phase change material in a fluorine-based solvent. The produced dispersion is particularly suitable as an excellent fuel cell stack coolant having high insulation and sufficient cooling performance as a heat / cooling medium in the vicinity of the operating temperature of a fuel cell or the like.

  As a result of diligent investigations to achieve the above object, the present inventors, first, there are many types of microencapsulant monomers that can be used, and organics that can select microencapsulant monomers suitable for water-soluble phase change substances. By dispersing the water-soluble phase change material particles using a solvent, and then adding a fluorinated solvent by a specific method, the strength of the microencapsulated wall covering the water-soluble phase change material is strong and water-soluble A method for dispersing a microencapsulated water-soluble phase-change material with little sedimentation of phase-change material particles in a fluorinated solvent has been found, and the present invention has been completed.

  That is, first, the present invention is an invention of a method for dispersing a microencapsulated phase change material in a fluorine-based solvent, and a step of producing an organic solvent dispersion of a microencapsulated phase change material, and (A) production An organic solvent dispersion of the microencapsulated phase change material, (B) a fluorine-based dispersion medium that does not dissolve in the microencapsulated phase-change material dispersion, and (C) a fluorine-based surface active that dissolves in the fluorine-based dispersion medium A step of mixing an agent, and a step of removing the organic solvent after phase separation from the mixed solution.

  This makes it possible to microencapsulate water-soluble phase change substances in an organic solvent that can select microencapsulant monomers suitable for water-soluble phase change substances. Therefore, microencapsulated water-soluble phase change material particles having a strong microencapsulation wall covering the water-soluble phase change material can be obtained. Furthermore, since the microencapsulated water-soluble phase change material particles are filtered and phase separated and transferred to the fluorinated solvent in the solution without becoming solid, the water-soluble phase change material particles are not coalesced and the settling property is reduced. A microencapsulated water-soluble phase change material dispersion dispersed in a small amount of a fluorinated solvent can be obtained.

  In the present invention, when the step of preparing the organic solvent dispersion of the microencapsulated phase change material disperses the water-soluble phase change material particles through the dispersion film in the organic solvent containing the microencapsulating agent. At the same time, it is preferable that the microencapsulation reaction proceeds at the water-soluble phase change material particle interface.

  Thus, according to the above configuration, the water-soluble phase change material particles are dispersed in the organic solvent containing the microencapsulating agent via the dispersion film, and at the same time, the microparticles are mixed at the water-soluble phase change material particle interface. Since the encapsulation reaction proceeds, the number of microcapsule particles that do not encapsulate the water-soluble phase change substance is reduced.

  In the step of preparing the organic solvent dispersion of the microencapsulated phase change material of the present invention, it is preferable that the organic solvent dispersion of the microencapsulated phase change material does not contain a surfactant that dissolves in the organic solvent.

  As a result, since the organic solvent does not contain an emulsifier that dissolves in the organic solvent, the dispersion of the microencapsulated water-soluble phase change material dispersed in the organic solvent contains a fluorine-based solvent that dissolves in the fluorine-based solvent and the fluorine-based solvent. When a surfactant is added, the interface between the organic solvent to be formed and the dispersion of the microencapsulated water-soluble phase change material dispersed in the fluorinated solvent is clear, making it very easy to separate the organic solvent. It is.

  In the step of preparing the organic solvent dispersion of the microencapsulated phase change material of the present invention, a wide variety of known microencapsulating agents can be used. Of these, the microencapsulating agent is preferably a water-curable urethane monomer or urethane prepolymer.

  As a result, water contained in the water-soluble phase change material can be used as a polymerization initiator for the microencapsulation reaction (polymerization), so that the microencapsulation reaction occurs at the interface of the water-soluble phase change material. The number of particles containing only the microencapsulating agent that is not encapsulated can be reduced.

  As the phase change material of the microencapsulated phase change material prepared in the present invention, known materials are widely used. Among these, a phase change substance selected from the group consisting of inorganic salt hydrates, saccharides, alcohols, urea and thiourea is preferable. Inorganic salt hydrates and sugar alcohols have a feature that they have a large latent heat of fusion per unit volume and do not change in quality even after repeated melting and solidification.

  Second, the present invention is a dispersion in which the microencapsulated phase change material produced by the above method is dispersed in a fluorinated solvent. Since a fluorine-based dispersion medium having no flammability is used as the dispersion medium, a dispersion liquid of a microencapsulated phase change material having no flammability can be obtained.

  Third, the present invention provides a fuel cell stack coolant in which the microencapsulated phase change material produced by the above method is dispersed in a fluorine-based solvent.

  Microencapsulated water-soluble phase change with few microcapsule particles that do not encapsulate water-soluble phase change material, sufficient strength of microencapsulation wall covering water-soluble phase change material, and low sedimentation of water-soluble phase change material particles A dispersion of the substance in a fluorinated solvent can be obtained. In particular, an excellent dispersion having high insulating properties and sufficient cooling performance can be obtained as a heat / cooling medium for fuel cells and the like.

  The solvent containing the microencapsulating agent used in the present invention is not particularly limited as long as it is an organic solvent and can dissolve the microencapsulating agent. Specifically, hebenzene, toluene, xylene, alkyl-substituted benzene, naphthalene, alkyl-substituted naphthalene, aromatic hydrocarbons such as phenol, cresol, alkyl-substituted phenol, paraffins such as hexane, heptane, and octane, cyclohexane, cyclohexane Preferred examples include cyclic saturated hydrocarbons such as pentane. A mixture of gasoline, light oil, kerosene, etc. can also be used. These microencapsulating agent-containing solvents can be used alone or in combination.

  The fluorinated solvent is not particularly limited as long as it is not homogeneously mixed with an organic solvent. Specifically, perfluoropolyether, perfluorocarbon, hydrofluoroether and the like can be preferably exemplified. These fluorinated solvents may be used alone or in combination.

  The water-soluble phase change material used in the present invention is not particularly limited. Specifically, potassium carbonate hexahydrate, lithium nitrate trihydrate, sodium sulfate decahydrate, sodium carbonate decahydrate, sodium thiosulfate pentahydrate, nickel nitrate hexahydrate, sodium acetate Trihydrate, iron nitrate hexahydrate, aluminum nitrate nonahydrate, sodium borate decahydrate, barium hydroxide octahydrate, strontium hydroxide octahydrate, magnesium nitrate hexahydrate , Inorganic salt hydrates such as aluminum sulfate decahydrate magnesium chloride hexahydrate, sugars such as ribose, maltose monohydrate, fructose, sucrose, lactose monohydrate, erythritol, threitol, xylitol, sorbitol, multi Preferred examples include alcohols such as Toll. Preferred examples of the nitrogen-containing compound include urea, thiourea, and acetamide.

  In order to improve the apparent specific heat of the microencapsulated water-soluble phase change substance, it is preferable that the latent heat of fusion per unit volume is large. From this viewpoint, inorganic salt hydrate, sugar alcohol, urea, thiourea are dissolved in water. It is preferable to use it as a sex phase change substance.

  These water-soluble phase change materials can be used alone or in combination. In addition, in order to adjust the melting point, a low-molecular water-soluble substance such as water, methanol, ethanol, ethylene glycol, or glycerin may be included.

  The microencapsulating agent used in the present invention is not particularly limited as long as it is polymerized and polymerized. Specifically, vinyl compounds, polyesters, polyamides, polyurethanes, phenol resins, melamine resins and the like can be preferably exemplified.

  The microencapsulating agent using water as an initiator in the present invention is not particularly limited as long as it uses water as an initiator. Specifically, anionic polymerizable monomers such as styrene, divinylbenzene, methacrylic acid ester, acrylic acid ester, acrylonitrile, vinylidene cyanide, ring opening of ε-caprolactam, β-propiolactone, ethyleneimine, tetramethylsiloxane, etc. Preferred examples include polymerizable monomers, water-curable urethane monomers, and prepolymers.

  The water-curing urethane monomer is not particularly limited as long as it has an isocyanate group at a terminal and reacts with water to cause a polymerization reaction. Specifically, preferred examples include tolylene diisocyanate (TDI) monomers or prepolymers thereof, diphenylmethane diisocyanate (MDI) monomers or prepolymers thereof, hexamethylene diisocyanate (HDI) monomers or prepolymers thereof. it can.

  These microencapsulating agents can be used alone or in combination.

  Hereinafter, a method for dispersing the microencapsulated water-soluble phase change material in a fluorine-based solvent will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram of a method for dispersing a microencapsulated phase change material of the present invention in a fluorinated solvent. An organic solvent dispersion of the microencapsulated phase change material is prepared, and a fluorine-based dispersion medium fluorine surfactant that does not dissolve in the microencapsulated phase change material dispersion is dissolved. Next, (A) the organic solvent dispersion of the prepared microencapsulated phase change material, (B) a fluorine-based dispersion medium that does not dissolve in the microencapsulated phase-change material dispersion, and (C) the fluorine-based dispersion medium A fluorine-based surfactant that dissolves in the mixture is mixed. Finally, these mixed liquids are allowed to stand or are centrifuged to cause phase separation, and the organic solvent after phase separation is removed.

  FIG. 2 is an explanatory diagram relating to a microencapsulation method of a water-soluble phase change material using a dispersion film according to an embodiment of the present invention. As shown in FIG. 1, the present embodiment includes a water-soluble phase change material container, a dispersion film, and a microencapsulating agent solution container, but is not limited thereto.

  In the water-soluble phase change material container 1, a water-soluble phase change material melt 2 in which the water-soluble phase change material is heated to the melting point or higher is prepared. The temperature of the melt is not particularly limited as long as the water-soluble phase change material is at or above the melting point, but from the viewpoint of stably melting, the melting point is preferably at or above 5 ° C.

  The water added to the water-soluble phase change material is appropriately selected from 0% by mass to 20% by mass in consideration of the water consumption of the microencapsulating agent. When the amount of water to be added is small, the hydrated water of the inorganic salt hydrate is used for the microencapsulation reaction, which decreases the latent heat of fusion of the water-soluble phase change material, and the amount of water to be added is large In consideration of the fact that water not used in the microencapsulation reaction lowers the melting point of the water-soluble phase change material, the water added to the water-soluble phase change material is 5% by mass to 10% by mass. Is preferred.

  At this time, the melting operation of the water-soluble phase change material may be heated by an electric heater (not shown) provided in the water-soluble phase change material container 1, or a separately melted solution is supplied to the electric heater. (It is not shown). From the viewpoint of preventing the water contained in the water-soluble phase change material from scattering, the water-soluble phase change material container 1 is preferably a closed system, and preferably has a pressure resistant structure equal to or higher than the vapor pressure of water at the melting temperature.

  The microencapsulating agent solution container 6 is prepared with a microencapsulating agent solution 7 in which a microencapsulating agent is dissolved in an organic solvent. The microencapsulating agent solution 7 is heated to a temperature near the melting point of the water-soluble phase change material. Here, the temperature near the melting point of the water-soluble phase change substance is not a problem as long as the water-soluble phase change substance does not solidify when dispersed in the solution. The sex phase change material is selected from a melting point plus 50 ° C. to minus 20 ° C., but preferably the water soluble phase change material has a melting point plus 30 ° C. to minus 10 ° C.

  The concentration of the microencapsulating agent solution 7 is not particularly limited as long as the fluidity can be maintained, and is appropriately selected from 1% by mass to 100% by mass. When a monomer is used as the microencapsulating agent, the fluidity can be maintained even at a high mass concentration, so that 10 mass% to 100 mass% is preferable. When using a prepolymer, 1 mass%-50 mass% are preferable in order to ensure fluidity | liquidity.

  A solvent that dissolves the microencapsulating agent may contain a small amount of a surfactant in order to improve the dispersion of the water-soluble phase change material. The content of the surfactant is selected from 0.1% by mass to 5% by mass with respect to the water-soluble phase change material to be added. To strengthen the microencapsulation reaction, the content is 1% by mass or less. It is particularly preferable that no surfactant is contained.

  At this time, the heating operation of the microencapsulating agent solution 7 may be performed by an electric heater (not shown) provided in the microencapsulating agent solution container 6, or a separately heated solution is supplied and the electric heating heater is supplied. (It is not shown). From the viewpoint of preventing the solvent contained in the microencapsulating agent solution 7 from scattering, the microencapsulating agent solution container 6 is preferably a closed system, and preferably has a pressure resistant structure equal to or higher than the vapor pressure of the solvent at the heating temperature. .

  The heated microencapsulating agent solution 7 at a predetermined temperature is supplied from the microencapsulating agent solution container 6 to the dispersion membrane container 5 through the microencapsulating agent supply line 10 by the microencapsulating agent circulation pump 9. Then, it is returned to the microencapsulant solution container 6 through the microencapsulant return line 11. The microencapsulating agent circulation pump 9, the microencapsulating agent supply line 10, the dispersion membrane container 5, and the microencapsulating agent return line 11 are provided with an electric heater (not shown) in order to keep the temperature of the microencapsulating agent solution 7 at a predetermined temperature. )).

  The microencapsulating agent circulation pump 9 is not particularly limited as long as it does not destroy the microcapsules, but a diaphragm pump, a plunger pump, a rotary pump, a tubing pump, a centrifugal pump and the like can be preferably exemplified.

  The amount of the microencapsulating agent solution 7 supplied is such that the linear velocity in the dispersion membrane container 5 is such that the water-soluble phase change material formed into droplets through the dispersion membrane promotes desorption from the membrane surface, Is preferably 0.01 m / s or more, but from the viewpoint of pressure loss of the microencapsulating agent supply line 10, the dispersion membrane container 5, and the microencapsulating agent return line 11, it is 10 m / s or less. It is preferable that

  When the microencapsulating agent solution 7 is circulated and the temperature of the microencapsulating agent solution 7 is stabilized at a predetermined temperature, the water-soluble phase change material melt 2 is changed from the water-soluble phase change material container 1 to the water-soluble phase change. The material is supplied to the inner surface of the dispersion film 4 through the substance melt supply line 3. The water-soluble phase change material melt 2 supplied to the inner surface of the dispersion film 4 forms droplets in the circulating microencapsulating agent solution 7 through the pores of the dispersion film 4, and the solution Due to the microencapsulating agent contained therein, the microencapsulation reaction immediately proceeds to form a microencapsulated wall at the water-soluble phase change material particle interface.

  The water-soluble phase change material container 1 may be supplied by pressurizing the water-soluble phase change material container 1 (not shown) or by supplying a pump ( (Not shown) may be installed and supplied.

  The formed microencapsulated particles complete the microencapsulation reaction during circulation. During the circulation operation of the microencapsulating agent solution 7, the microencapsulating agent solution container 6 is stirred by the stirring device 8 provided in the microencapsulating agent solution container 6 to unite the microencapsulated particles. It is preferable to prevent.

  The material of the dispersion film 4 is not particularly limited as long as uniform pores are formed, and examples thereof include polymer films such as polyimide and polysulfone, and ceramic films such as shirasu glass, alumina, titania, and zirconia. It is preferable to use a ceramic film from the viewpoint of excellent heat resistance and corrosion resistance because it contacts the molten inorganic salt hydrate at a relatively high temperature.

  The pore diameter of the dispersion film 4 is not particularly limited as long as the water-soluble phase change substance is stably dispersed, but those having a diameter of 10 nm to 10 μm are preferably used. In order that the microencapsulated particles of the water-soluble phase change substance exist stably in the organic solvent medium, a dispersion film having a pore diameter of 1 μm or less is preferable.

  Water-soluble phase change material container 1, water-soluble phase change material melt supply line 3, dispersion membrane container 5, microencapsulant solution container 6, stirring device 8, microencapsulant circulation pump 9, microencapsulant supply line 10. The material of the microencapsulating agent return line 11 is not particularly limited as long as it can withstand the temperature to be used and has resistance to the liquid in contact therewith. Specifically, polymer materials such as Teflon (trade name), silicone, and polystyrene, metal materials such as carbon steel, stainless steel, nickel steel, and titanium materials, and inorganic materials such as glass and ceramics can be preferably exemplified.

  Cooling the obtained dispersion of the microencapsulated water-soluble phase change material to room temperature, adding and stirring a fluorinated solvent containing a fluorinated emulsifier to the dispersion dispersed in an organic solvent, and allowing to stand and separate To disperse microencapsulated water-soluble phase-change material particles in a fluorine-based solvent by transferring the microencapsulated water-soluble phase-change material into the fluorine-based solvent and phase-separating the organic solvent. Obtain a liquid.

  The amount of the chlorofluorocarbon-containing solvent containing the fluorine-based emulsifier added to the dispersion dispersed in the organic solvent is not particularly limited, but is preferably 20% by volume to 200% by volume with respect to the organic solvent dispersion. When the addition amount of the fluorinated solvent is less than the volume of the organic solvent dispersion, it means that the amount of the microencapsulated water-soluble phase change material is concentrated, and the addition amount of the fluorinated solvent is the amount of the organic solvent dispersion. When the volume exceeds the volume, it means that the amount of the water-soluble phase change material encapsulated in the microcapsule is diluted. Therefore, in order to obtain a fluorine-based dispersion liquid containing a high concentration of the water-soluble phase change material, fluorine to be added is used. The amount of the fluorinated solvent containing the system emulsifier is particularly preferably 20% by volume to 100% by volume with respect to the organic solvent dispersion.

  The fluorinated emulsifier contained in the fluorinated solvent is not particularly limited as long as it is solubilized in the fluorinated solvent. Specifically, a perfluorocarbon base emulsifier containing sulfonic acid, carboxylic acid, dicarboxylic acid, and polyoxyethylene ether in the molecule can be preferably exemplified.

  These fluorine-based emulsifiers may be used alone or in combination.

  The amount of the fluorine-based emulsifier contained in the fluorine-based solvent is preferably 1% by mass to 50% by mass with respect to the weight of the microencapsulated water-soluble phase change material particles to be transferred into the fluorine-based solvent. . When the amount is 1% by mass or less, the dispersion of the water-soluble phase change substance in the fluorinated solvent is insufficient, and when the amount is 50% by mass or more, in addition to economic problems, the fluorinated dispersion becomes highly viscous. There's a problem.

  Stirring of the mixture obtained by adding the fluorinated solvent to the organic solvent dispersion is not particularly limited as long as it has a structure capable of stirring uniformly, and stirring by a magnetic rotor, stirring by a stirring blade, stirring by reciprocating motion, etc. are preferable examples it can.

  The stirring time is not particularly limited as long as it can be uniformly stirred. Specifically, about 1 min to 60 min is preferable.

  The phase separation time after the stirring of the mixture obtained by adding the fluorinated solvent to the organic solvent dispersion is not particularly limited. Specifically, about 10 min to 24 h is preferable.

  According to the method of the present invention, there are few microcapsule particles that do not contain a water-soluble phase change material, the strength of the microencapsulation wall that covers the water-soluble phase change material is sufficient, and the microcapsules have little sedimentation of the water-soluble phase change material particles It is possible to obtain a dispersion of the water-soluble phase change material converted into a fluorinated solvent.

Examples of the present invention will be described below.
[Example 1]
10% by mass of Takenate M-408 (manufactured by Mitsui Takeda Chemical Co., Ltd.), a tolylene diisocyanate prepolymer, in toluene dehydrated with Molecular Sieve 3A (manufactured by Nacalai Tesque Co., Ltd.) 200 ml of the prepared solution was heated to 85 ° C. while rotating at 300 rpm with a magnetic stirrer to prepare a microencapsulating agent solution container 6. Circulation was started by setting the flow rate of the microencapsulating agent circulation pump 9 (diaphragm pump) so that the linear velocity of the microencapsulating agent solution 7 in the dispersion membrane container 5 was 0.1 m / s.

  The dispersion film was made of α-alumina, and a ceramic filter (manufactured by Noritake Co., Ltd.) having an outer diameter of 10 mm, an inner diameter of 7 mm, a length of 200 mm and an average pore diameter of 250 nm was used.

  On the other hand, 15 ml of threitol (manufactured by API Corporation) with ion exchange water added to 3% by mass is heated to 85 ° C. to prepare a threitol melt. While maintaining the temperature at 85 ° C., applying nitrogen pressure after sealing, the thritol melt was added for about 5 min in the Takenate M-408 toluene solution maintained under stirring at 85 ° C. that was circulated outside the dispersion membrane. Extruded.

  Even after the extrusion of thritol, the Takenate M-408 toluene solution was kept stirring at 85 ° C. for 1 hour to complete the microencapsulation reaction. Thereafter, the microencapsulated dispersion is cooled to room temperature and contains 3 g of a fluorine-based emulsifier (trade name “Furgent 150”, manufactured by Neos) in 100 ml of perfluorocarbon (trade name “Fluorinert FC3255”, manufactured by Sumitomo 3M). Was added and stirred uniformly with a magnetic stirrer for 10 min.

  After completion of stirring, the mixture was allowed to stand at room temperature for 8 hours to obtain a water-soluble phase change material dispersion in which the upper phase was toluene and the lower phase was microencapsulated. The toluene in the upper layer was gently discharged to obtain 120 ml of a microencapsulated dispersion of water-soluble phase change material.

  Microencapsulated water-soluble phase-change material particles dispersed in a fluorinated solvent are measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba, Ltd.), and the volume average diameter is 0.5 μm. I confirmed that there was. The amount of threitol contained in the microencapsulated particles is an average value of the latent heat of fusion obtained by repeating the heating and cooling 10 times in the same sample using a differential thermal analyzer DSC3100 (manufactured by Mac Science Co., Ltd.). It was calculated by comparing with. The microencapsulated particles were found to contain 75% by weight of thritol.

[Example 2]
10% by mass of Takenate M-408 (manufactured by Mitsui Takeda Chemical Co., Ltd.), a tolylene diisocyanate prepolymer, in toluene dehydrated with Molecular Sieve 3A (manufactured by Nacalai Tesque Co., Ltd.) 200 ml of the prepared solution was heated to 65 ° C. while rotating at 300 rpm with a magnetic stirrer to prepare the microencapsulating agent solution container 6. Circulation was started by setting the flow rate of the microencapsulating agent circulation pump 9 (diaphragm pump) so that the linear velocity of the microencapsulating agent solution 7 in the dispersion membrane container 5 was 0.1 m / s.

  On the other hand, 15 ml of sodium acetate trihydrate (manufactured by Nacalai Tesque Co., Ltd., special grade reagent) with ion exchange water added to 5 mass% is heated to 65 ° C., and sodium acetate trihydrate melt Takenate M maintained under stirring at 65 ° C. circulated outside the dispersion membrane by adding nitrogen pressure after sealing and placing in water-soluble phase change material container 1 while keeping at 65 ° C. A sodium acetate trihydrate melt was extruded into a -408 toluene solution in about 5 minutes.

  The dispersion film was made of α-alumina, and a ceramic filter (manufactured by Noritake Co., Ltd.) having an outer diameter of 10 mm, an inner diameter of 7 mm, a length of 200 mm and an average pore diameter of 250 nm was used.

  Even after the sodium acetate trihydrate melt was extruded, the Takenate M-408 toluene solution was kept stirring at 65 ° C. for 1 h to complete the microencapsulation reaction. Thereafter, the microencapsulated dispersion is cooled to room temperature and contains 3 g of a fluorine-based emulsifier (trade name “Furgent 150”, manufactured by Neos) in 100 ml of perfluorocarbon (trade name “Fluorinert FC3255”, manufactured by Sumitomo 3M). Was added and stirred uniformly with a magnetic stirrer for 10 min.

  After completion of stirring, the mixture was allowed to stand at room temperature for 8 hours to obtain a water-soluble phase change material dispersion in which the upper phase was toluene and the lower phase was microencapsulated. The toluene in the upper layer was gently discharged to obtain 120 ml of a microencapsulated dispersion of water-soluble phase change material.

  Microencapsulated water-soluble phase change material particles dispersed in a fluorinated solvent were measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba, Ltd.), and the volume average diameter was 0.6 μm. I confirmed that there was. The amount of sodium acetate trihydrate contained in the microencapsulated particles is the average value of the latent heat of fusion obtained by repeating heating and cooling 10 times in the same sample using a differential thermal analyzer DSC3100 (manufactured by Mac Science Co., Ltd.) It calculated | required by comparing with the literature value of sodium acetate trihydrate. It was found that the microencapsulated particles contained 75% by mass of sodium acetate trihydrate.

[Comparative example]
450 ml (769.5 g) of perfluorocarbon (trade name “Fluorinert FC3255”, manufactured by Sumitomo 3M) was heated to 65 ° C., melted therein and heated to 70 ° C. (Nacalai Tesque) 50 ml (104 g) and 2.5 g of a fluorine-based emulsifier (trade name “Futagent 150”, manufactured by Neos) were added and pre-emulsified for 5 minutes at a rotation speed of 10,000 rpm with a high-speed rotation homogenizer while keeping the temperature at 70 ° C. Was done. The pre-emulsified emulsion is subjected to high-pressure emulsification for 10 minutes at a pressure of 100 MPa while maintaining the temperature of the dispersion at 70 ° C. with a high-pressure emulsifier (manufactured by Nirosoavi). A trihydrate dispersion was obtained. The average particle size of sodium acetate trihydrate was measured with a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba Seisakusho), and the volume average particle size was 0.4 μm in sodium acetate trihydrate dispersion. A liquid was obtained. 500 ml of the dispersion thus obtained was put into a stirrer, stirred at a rotation speed of 200 rpm with a turbine blade, and kept at 60 ° C. at a temperature of 25 ml (22.6 g) of styrene monomer (Nacalai). Tesque) and 1.25 ml (1.13 g) divinylbenzene (Wako Pure Chemical Industries, Ltd.) were added and stirred for 10 minutes. Thereto, 0.47 g of polymerization initiator ACVA (4,4′-azobis-4-cyanovaleric acid) (manufactured by Otsuka Chemical Co., Ltd.) was added, and the polymerization reaction was carried out at 60 ° C. for 12 hours. Obtained.

  The microencapsulated water-soluble phase change material particles dispersed in a fluorine-based solvent are measured by a laser diffraction / scattering particle size distribution analyzer LA-910 (manufactured by Horiba, Ltd.), and the volume average diameter is 0.6 μm. It was confirmed. For the amount of sodium acetate trihydrate contained in the microencapsulated particles, heating and cooling were repeated 10 times for the same sample using a differential thermal analyzer DSC3100 (manufactured by Mac Science Co., Ltd.). The amount of latent heat of fusion at the first time was 75% of the literature value of nadlium acetate trihydrate, but the peak of the differential thermal analysis system was not observed after the second time. Since the microencapsulated wall is not strong, water is scattered from sodium acetate hydrate, and the peak of latent heat of fusion is not observed.

  Applications of the method for dispersing the microencapsulated water-soluble phase change material of the present invention in a fluorinated solvent include applications such as a coolant medium for automobile engines and fuel cells, and a heat transfer medium for heat storage systems. Compared to a conventional heat transfer medium, the electric conductivity is small and the apparent specific heat per unit volume is large. Therefore, the circulation flow rate of the medium can be reduced, which contributes to energy saving. In particular, an excellent dispersion having high insulation and sufficient cooling performance, which is useful as a heat / cooling medium for fuel cells and the like, can be obtained, which contributes to the practical use and spread of fuel cells.

It is a conceptual diagram of the dispersion method to the fluorine-type solvent of the microencapsulation phase change substance of this invention. It is explanatory drawing regarding the microencapsulation method of the water-soluble phase change substance by the dispersion film of one Embodiment of this invention.

Explanation of symbols

1: Water-soluble phase change substance container, 2: Water-soluble phase change substance melt, 3: Water-soluble phase change substance melt supply line, 4: Dispersion film, 5: Dispersion film container, 6: Microencapsulant solution container 7: Microencapsulant solution, 8: Stirrer, 9: Microencapsulant circulation pump, 10: Microencapsulant supply line, 11: Microencapsulant return line

Claims (6)

Producing an organic solvent dispersion of the microencapsulated phase change material obtained by microencapsulating the phase change material;
(A) Organic solvent dispersion of the prepared microencapsulated phase change material, (B) fluorinated solvent not soluble in the microencapsulated phase change material dispersion, and (C) fluorinated solvent soluble in the fluorinated solvent. Mixing a surfactant;
Separating the organic solvent and the fluorinated solvent containing the fluorinated surfactant to transfer the microencapsulated phase change material into the fluorinated solvent;
A method for dispersing a microencapsulated phase change material in a fluorinated solvent, comprising a step of removing the organic solvent after phase separation from a mixed solution ,
The phase change material is potassium carbonate hexahydrate, lithium nitrate trihydrate, sodium sulfate decahydrate, sodium carbonate decahydrate, sodium thiosulfate pentahydrate, nickel nitrate hexahydrate, acetic acid Sodium trihydrate, iron nitrate hexahydrate, aluminum nitrate nonahydrate, sodium tetraborate decahydrate, barium hydroxide octahydrate, strontium hydroxide octahydrate, magnesium nitrate hexahydrate , Aluminum sulfate decahydrate, magnesium chloride hexahydrate, ribose, maltose monohydrate, fructose, sucrose, lactose monohydrate, erythritol, threitol, xylitol, sorbitol, maltitol, urea, thiourea and At least one selected from acetamide,
The organic solvent is at least selected from benzene, toluene, xylene, alkyl-substituted benzene, naphthalene, alkyl-substituted naphthalene, phenol, cresol, alkyl-substituted phenol, hexane, heptane, octane, cyclohexane, cyclopentane, gasoline, light oil and kerosene. A method of dispersing the microencapsulated phase change material in one type of fluorine-based solvent . Almost simultaneously with the step of preparing the organic solvent dispersion of the microencapsulated phase change material, the water-soluble phase change material particles are dispersed in the organic solvent containing the microencapsulating agent through the dispersion film. characterized in that it is intended to advance the microencapsulation reaction with a water-soluble phase change material particle interface, a method of dispersing the fluorinated solvent of microencapsulated phase change material according to claim 1. 3. The fluorine-based microencapsulated phase change material according to claim 1 , wherein the organic solvent dispersion of the microencapsulated phase change material does not contain a surfactant that is soluble in the organic solvent. 4. Dispersion method in solvent. Wherein the microencapsulated agent is a prepolymer of a monomer or urethane of the urethane of water-curable, dispersion in Freon-based solvents microencapsulated phase change material according to any one of claims 1 to 3 Method. Dispersions microencapsulated phase change material is dispersed into the fluorine-based solvent produced by the process according to any one of claims 1 to 4. The fuel cell stack cooling liquid microencapsulated phase change material is dispersed into the fluorine-based solvent produced by the process according to any one of claims 1 to 4.

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