JP7394436B2 - Particles for temperature-sensitive magnetic fluid, temperature-sensitive magnetic fluid, method for producing particles for temperature-sensitive magnetic fluid, and method for producing temperature-sensitive magnetic fluid - Google Patents

Description

The present invention relates to particles for temperature-sensitive magnetic fluids, temperature-sensitive magnetic fluids, methods for producing particles for temperature-sensitive magnetic fluids, and methods for producing temperature-sensitive magnetic fluids.

2. Description of the Related Art Conventionally, temperature-sensitive magnetic fluids in which fine particles of ferromagnetic material are dispersed in a dispersion medium such as water or oil have been known. The particle size of the fine particles is typically about 10 nm. Temperature-sensitive magnetic fluids have magnetic susceptibility that changes depending on temperature, so they are driven spontaneously when there is a temperature difference under a magnetic field. Therefore, it is possible to flow the temperature-sensitive magnetic fluid without using an external power source, and in recent years, it has attracted attention as a device for cooling and the like.

When fine particles of ferromagnetic material in a liquid come close to each other, attractive forces such as magnetic attractive force and van der Waals force act on them. A surfactant is used to generate a repulsive force that resists these attractive forces (see, for example, Patent Document 1). The surfactant is selected to have irreversible adsorption properties on the particle surface and to be compatible with the dispersion medium. In Patent Document 1, a surfactant containing a mercapto group is adsorbed on the surface of ferromagnetic metal oxide fine particles. By using a surfactant, a steric hindrance effect occurs between adsorbed molecules on the particle surface, and a repulsive force that resists the attraction force between particles can be obtained.

JP 2018-41807 Publication

However, in conventional temperature-sensitive magnetic fluids, it is not easy to find a surfactant that is compatible with the dispersion medium. If an appropriate surfactant is not present, the dispersion medium cannot be used, and the dispersion medium that can be used is limited.

Furthermore, since the particle size of the fine particles of the ferromagnetic material is small, when pressure is applied to the temperature-sensitive magnetic fluid, it tends to become clay-like. Once the temperature-sensitive magnetic fluid has become clay-like, the adsorption force between particles is strong, and even if the pressure is released, it is difficult to redisperse the particles. As a result, there is a problem in that the temperature-sensitive magnetic fluid becomes clay-like and tends to clog the flow path. In order to solve this problem, it is possible to increase the particle size of the ferromagnetic material particles, but when the particle size is increased, magnetic attraction becomes dominant, and the particles aggregate and precipitate even when no pressure is applied. , the fine particles cannot be accurately dispersed in the dispersion medium.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to dramatically improve the degree of freedom in selecting a dispersion medium, and to improve redispersion after pressure is applied to the fluid. Provided are particles for a temperature-sensitive magnetic fluid with excellent properties, a temperature-sensitive magnetic fluid in which the particles for the temperature-sensitive magnetic fluid are dispersed, a method for producing the particles for the temperature-sensitive magnetic fluid, and a method for producing the temperature-sensitive magnetic fluid. There is a particular thing.

In order to achieve the above object, the present invention provides a temperature-sensitive magnetic fluid comprising a plurality of temperature-sensitive magnetic particles made of a ferromagnetic material and a skeleton part made of a non-magnetic material and containing the plurality of temperature-sensitive magnetic particles. Particles are provided.

According to this temperature-sensitive magnetic fluid particle, since the temperature-sensitive magnetic particles are encapsulated in the skeleton, even if an attractive force such as magnetic attraction force or van der Waals force acts between the temperature-sensitive magnetic particles, The skeleton interposed between the temperature-sensitive magnetic particles causes a steric hindrance effect, and it is possible to obtain a repulsive force that resists the attractive force between the temperature-sensitive magnetic particles. In other words, regardless of the dispersion medium in which the temperature-sensitive magnetic fluid particles are dispersed, it is possible to always obtain a repulsive force that resists the attractive force between the temperature-sensitive magnetic particles, dramatically improving the degree of freedom in selecting the dispersion medium. be able to.
Moreover, since a plurality of temperature-sensitive magnetic particles are included, the overall particle size of the particles for temperature-sensitive magnetic fluid is larger than the particle size of each of the temperature-sensitive magnetic particles. As a result, even if pressure is applied to the temperature-sensitive magnetic fluid in which the temperature-sensitive magnetic fluid particles are dispersed, it is unlikely to become clay-like, and even if it becomes clay-like, the temperature-sensitive magnetic fluid particles are large. The adsorption force between them is weak, and the redispersibility of the temperature-sensitive magnetic fluid particles after the pressure is released can be improved.
Furthermore, since each temperature-sensitive magnetic particle is covered with the skeleton, each temperature-sensitive magnetic particle can be protected. This improves the oxidation resistance of the temperature-sensitive magnetic particles.

In the temperature-sensitive magnetic fluid particles described above, the skeleton portion may be made of plastic .

In the temperature-sensitive magnetic fluid particle described above, the skeleton portion may have a plurality of bubbles inside.

The temperature-sensitive magnetic fluid particles may further include a latent heat storage material included in the skeleton together with the plurality of temperature-sensitive magnetic particles.

Further, according to the present invention, there is provided a temperature-sensitive magnetic fluid comprising the temperature-sensitive magnetic fluid particles and a dispersion medium in which the temperature-sensitive magnetic fluid particles are dispersed.

Further, according to the present invention, there is provided a method for producing particles for a temperature-sensitive magnetic fluid, including a solution generation step of dissolving a polymer, which is a raw material for the skeleton, in an organic solvent to generate a skeleton solution; a primary dispersion step of dispersing the temperature-sensitive magnetic fluid containing the temperature-sensitive magnetic particles or the temperature-sensitive magnetic particles in the skeleton solution generated in the solution generation step to generate a primary dispersion; and the primary dispersion step. a secondary dispersion step of dispersing the primary dispersion produced in the organic solvent in an external phase solution that is immiscible with the organic solvent to produce a secondary dispersion; and There is provided a method for producing particles for a temperature-sensitive magnetic fluid, the method comprising: removing the organic solvent from the dispersion liquid and precipitating the skeleton in a state in which a plurality of the temperature-sensitive magnetic particles are encapsulated. .

Furthermore, according to the present invention, there is provided a method for producing the temperature-sensitive magnetic fluid particles, comprising: dissolving a polymer, which is a raw material for the skeleton, in an organic solvent to generate a skeleton solution; a primary dispersion step of dispersing the temperature-sensitive magnetic fluid containing the temperature-sensitive magnetic particles or the temperature-sensitive magnetic particles in the skeleton solution generated in the solution generation step to generate a primary dispersion; and the primary dispersion. a secondary dispersion step of producing a secondary dispersion by dispersing the primary dispersion produced in the step into an external phase solution that is immiscible with the organic solvent with air mixed therein; a skeleton part precipitation step of removing the organic solvent from the secondary dispersion liquid generated in the dispersion process and precipitating the skeleton part in a state in which a plurality of the temperature-sensitive magnetic particles and the air bubbles are included. A method of making particles for a temperature sensitive magnetic fluid is provided.

In the method for producing particles for a temperature-sensitive magnetic fluid, the secondary dispersion is maintained at a temperature near the boiling point of the organic solvent for a predetermined period of time in the skeleton precipitation step, and The organic solvent in the secondary dispersion may be dissolved in the external phase solution and volatilized from the external phase solution.

Furthermore, according to the present invention, there is provided a method for producing the temperature-sensitive magnetic fluid, wherein a polymer as a raw material for the skeleton is dissolved in an organic solvent that is immiscible with the dispersion medium to produce a skeleton solution. liquid generation step, and a primary dispersion step of dispersing the temperature-sensitive magnetic fluid containing the temperature-sensitive magnetic particles or the temperature-sensitive magnetic particles in the skeleton solution generated in the solution generation step to generate a primary dispersion liquid. and a secondary dispersion step of dispersing the primary dispersion produced in the primary dispersion step in the dispersion medium to produce a secondary dispersion, and the secondary dispersion produced in the secondary dispersion step. A method for producing a temperature-sensitive magnetic fluid, comprising: removing the organic solvent from the dispersion liquid, and precipitating the skeleton in the dispersion medium with a plurality of the temperature-sensitive magnetic particles encapsulated therein. provided.

According to the present invention, the degree of freedom in selecting a dispersion medium is dramatically improved, and it is possible to obtain a temperature-sensitive magnetic fluid with excellent redispersibility of particles for the temperature-sensitive magnetic fluid after pressure is applied to the fluid. can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a temperature-sensitive magnetic fluid showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of particles for temperature-sensitive magnetic fluid. It is a flowchart which shows the manufacturing process of the particle|grains for temperature-sensitive magnetic fluids. It is a schematic cross-sectional explanatory view of a primary dispersion liquid in which temperature-sensitive magnetic particles are dispersed in a skeleton solution. FIG. 2 is a schematic cross-sectional explanatory diagram showing a state in which a primary dispersion liquid is mixed with an external phase solution. FIG. 2 is a schematic cross-sectional explanatory diagram showing a state in which a primary dispersion liquid is dispersed in an external phase solution. FIG. 2 is a schematic cross-sectional explanatory diagram showing a state in which the organic solvent in the skeleton solution has been removed. It is a schematic cross-sectional explanatory view of particles for temperature-sensitive magnetic fluids showing a modified example. It is a schematic cross-sectional explanatory view of particles for temperature-sensitive magnetic fluids showing a modified example. It is a graph showing the rheological properties of Examples and Comparative Examples, where (a) shows the Examples and (b) shows the Comparative Examples.

1 to 7 show one embodiment of the present invention, FIG. 1 is an explanatory diagram of a temperature-sensitive magnetic fluid, FIG. 2 is a schematic cross-sectional diagram of particles for a temperature-sensitive magnetic fluid, and FIG. 3 is an explanatory diagram of a temperature-sensitive magnetic fluid. A flowchart showing the manufacturing process of fluid particles, FIG. 4 is a schematic cross-sectional explanatory diagram of a primary dispersion liquid in which temperature-sensitive magnetic particles are dispersed in a skeleton solution, and FIG. 5 is a schematic diagram showing a state in which the primary dispersion liquid is mixed with an external phase solution. FIG. 6 is a schematic cross-sectional view showing a state in which the primary dispersion liquid is dispersed in the external phase solution, and FIG. 7 is a schematic cross-sectional view showing a state in which the organic solvent in the skeleton solution is removed. Incidentally, the temperature-sensitive magnetic fluid particles, temperature-sensitive magnetic particles, and bubbles in each figure are shown only schematically, and are different from the actual size, shape, etc.

As shown in FIG. 1, the temperature-sensitive magnetic fluid particles 1 have temperature-sensitive magnetism and are used by being dispersed in a dispersion medium 3 of the temperature-sensitive magnetic fluid 2. FIG. 1 shows a state in which a predetermined flow path 100 is filled with temperature-sensitive magnetic fluid 2. As shown in FIG.

As shown in FIG. 2, the temperature-sensitive magnetic fluid particle 1 includes a plurality of temperature-sensitive magnetic particles 10 made of a ferromagnetic material, and a skeleton part 11 made of a non-magnetic material and containing each temperature-sensitive magnetic particle 10. have That is, the skeleton part 11 has a plurality of spaces in which the temperature-sensitive magnetic particles 10 are accommodated. Furthermore, in this embodiment, the skeleton part 11 has a plurality of air bubbles 12 inside. The temperature-sensitive magnetic fluid particles 1 have a spherical shape. Although the particle size of the temperature-sensitive magnetic fluid particles 1 is arbitrary, it is appropriately set, for example, in the range of 1 μm or more and 1 mm or less depending on the specifications of the fluid.

In this embodiment, the temperature-sensitive magnetic particles 10 are made of a metal compound, and the skeleton portion 11 is made of plastic. Specifically, the temperature-sensitive magnetic particles 10 are made of magnetite, and the skeleton portion 11 is made of polylactic acid. Moreover, an ethylene glycol aqueous solution is used as the dispersion medium 3. In this embodiment, the particle size of the temperature-sensitive magnetic particles 10 is about 100 nm, and the particle size of the temperature-sensitive magnetic fluid particles 1 is about 10 μm. The temperature-sensitive magnetic particles 10 may be made of any material and have any particle diameter as long as they are ferromagnetic, and the material and outer diameter of the skeleton portion 11 may be arbitrary as long as they are non-magnetic. Further, as will be described later, by using the temperature-sensitive magnetic fluid particles 1 of this embodiment, the degree of freedom in selecting the dispersion medium 3 is improved, and the material of the dispersion medium 3 can also be changed arbitrarily. Further, the ratio of the particle diameters of the temperature-sensitive magnetic particles 10 and the temperature-sensitive magnetic fluid particles 1 is arbitrary, but for example, the particle size of the temperature-sensitive magnetic fluid particles 1 is 100 times or more the particle size of the temperature-sensitive magnetic particles 10. It can be 1000 times or less. As the temperature-sensitive magnetic particles 10, in addition to magnetite, other metal compounds such as ferrite can be used. In addition to polylactic acid, biodegradable plastics other than polylactic acid can of course be used as the skeleton 11, and plastics such as polyisobutyl methacrylate, methyl methacrylate, polystyrene, ABS resin, and polyvinyl chloride can also be used. Can be used. Although the dispersion medium 3 is arbitrary, various water-based and oil-based liquids can be used, and in addition to the ethylene glycol aqueous solution of this embodiment, for example, ethylene glycol, water, various alcohols, silicone oil, ammonia, and ammonia aqueous solution. , silicone oil, propylene glycol, propylene glycol aqueous solution, fluorine-based inert liquid, etc. can be used. Alternatively, the temperature-sensitive magnetic fluid particles 1 may be mixed into a paste-like material having a relatively high viscosity, such as a liquid gasket made of a silicone material.

The temperature-sensitive magnetic fluid particles 1 of this embodiment are manufactured through the following steps. The process will be explained below with reference to the flowchart shown in FIG.
First, a polymer, which is a raw material for the skeleton portion 11, is dissolved in an organic solvent to generate a skeleton solution 20 (solution generation step: S1). In this embodiment, a polylactic acid polymer is dissolved in dichloromethane as an organic solvent. The organic solvent can be appropriately selected depending on the polymer to be dissolved, and in addition to dichloromethane, toluene, acetone, thinner, chloroform, ethyl acetate, etc. can be used.

Next, as shown in FIG. 4, the temperature-sensitive magnetic particles 10 are dispersed in the skeleton solution 20 to generate a primary dispersion 21 (primary dispersion step: S2). Then, as shown in FIG. 5, this primary dispersion liquid 21 is mixed into an external phase solution 22 that is immiscible with an organic solvent, and then dispersed by stirring as shown in FIG. 6 to produce a secondary dispersion liquid 23 ( Secondary dispersion step: S3). In this embodiment, an ethylene glycol aqueous solution is used as the external phase solution 22. Further, in this embodiment, the primary dispersion liquid 21 is dispersed by stirring with a homomixer, and air bubbles 12 are mixed into the primary dispersion liquid 21 due to the impact at this time. Incidentally, if the air bubbles 12 are not required in the temperature-sensitive magnetic fluid particles 1 to be manufactured, the generation of the air bubbles 12 can be suppressed by weakening the impact force by the homomixer.

After that, the organic solvent is removed from the secondary dispersion liquid 23, and as shown in FIG. 7, the skeleton part 11 is precipitated in a state in which a plurality of temperature-sensitive magnetic particles 10 and air bubbles 12 are included (skeleton part precipitation step: S4). In this embodiment, the secondary dispersion liquid 23 is maintained at a temperature near the boiling point of the organic solvent for a predetermined period of time, the organic solvent in the primary dispersion liquid 21 is dissolved in the external phase solution 22, and the organic solvent is volatilized from the external phase solution 22 into the air. let At this time as well, bubbles 12 are generated within the primary dispersion liquid 21 due to the influence of the disturbance. Incidentally, if the air bubbles 12 are not required in the temperature-sensitive magnetic fluid particles 1 to be produced, by lowering the temperature of the secondary dispersion liquid 23 than the boiling point of the organic solvent, or by using an organic solvent with a relatively high boiling point, Generation of bubbles 12 can be suppressed. As a result, temperature-sensitive magnetic fluid particles 1 are generated in the external phase solution 22. Here, by selecting the desired dispersion medium 3 of the temperature-sensitive magnetic fluid as the external phase solution 22, it is possible to obtain the temperature-sensitive magnetic fluid 2 in which the temperature-sensitive magnetic fluid particles 1 are dispersed in the external phase solution 22. . In this embodiment, it is possible to obtain a temperature-sensitive magnetic fluid 2 in which temperature-sensitive magnetic fluid particles 1 are dispersed in an ethylene glycol aqueous solution. In addition, without using the external phase solution 22 as a dispersion medium for the temperature-sensitive magnetic fluid, after taking out the temperature-sensitive magnetic fluid particles 1 from the external phase solution 22, the temperature-sensitive magnetic fluid particles 1 are dispersed in a predetermined dispersion medium 3. Of course, it is possible.

According to the temperature-sensitive magnetic fluid particles 1 configured as described above, since the temperature-sensitive magnetic particles 10 are encapsulated by the skeleton portion 11, magnetic attraction force, van der Waals force, etc. are generated between the temperature-sensitive magnetic particles 10. Even if an attractive force of 2 is applied, a steric hindrance effect occurs due to the skeleton portion 11 interposed between the temperature-sensitive magnetic particles 10, and a repulsive force that resists the attractive force between the temperature-sensitive magnetic particles 10 can be obtained. That is, regardless of the dispersion medium 3 in which the temperature-sensitive magnetic fluid particles 1 are dispersed, it is possible to always obtain a repulsive force that resists the attractive force between the temperature-sensitive magnetic particles 10, greatly increasing the degree of freedom in selecting the dispersion medium 3. can be improved.

When temperature-sensitive magnetic particles are directly dispersed in a dispersion medium as in the past, it has been difficult to select an appropriate surfactant when antifreeze or a working fluid with high thermal conductivity is used as the dispersion medium. However, by encapsulating the temperature-sensitive magnetic particles 10 in the skeleton 11, agglomeration can be prevented, and the temperature-sensitive magnetic fluid particles 1 can be dispersed even in antifreeze or a working fluid with high thermal conductivity. can. In this way, the temperature-sensitive magnetic fluid particles 1 can be dispersed in a fluid that has conventionally been difficult to use as a dispersion medium to produce a temperature-sensitive magnetic fluid.

Further, since a plurality of temperature-sensitive magnetic particles 10 are included, the overall particle size of the temperature-sensitive magnetic fluid particles 1 is larger than the particle size of each of the temperature-sensitive magnetic particles 10. As a result, even if pressure is applied to the temperature-sensitive magnetic fluid 2 in which the temperature-sensitive magnetic fluid particles 1 are dispersed, it is unlikely to become clay-like, and even if it becomes clay-like, the temperature-sensitive magnetic fluid particles 1 are large. Therefore, the adsorption force between the particles is weak, and the redispersibility of the temperature-sensitive magnetic fluid particles 1 after the pressure is released can be improved.

Furthermore, since each temperature-sensitive magnetic particle 10 is covered with the skeleton part 11, each temperature-sensitive magnetic particle 10 can be protected. This improves the oxidation resistance and the like of the temperature-sensitive magnetic particles 10. In addition, conventionally, the particle size of the temperature-sensitive magnetic particles cannot be increased because they precipitate in the dispersion medium, but the particle size of the temperature-sensitive magnetic particles 10 can be increased within a range that can be accommodated in the skeleton section 11. can do. For example, conventionally, temperature-sensitive magnetic particles tend to precipitate in a dispersion medium when the particle size is 15 nm or more, but in the temperature-sensitive magnetic fluid particles 1 of the present embodiment, the temperature-sensitive magnetic particles 10 have a particle size of 15 nm or more. It is possible to do so. In this way, by increasing the particle size of the temperature-sensitive magnetic particles 10, it is possible to shorten the manufacturing time of the temperature-sensitive magnetic particles 10 and to reduce the manufacturing cost of the temperature-sensitive magnetic particles 10.

Furthermore, since the skeleton portion 11 contains the air bubbles 12, the specific gravity of the temperature-sensitive magnetic fluid particles 1 in the dispersion medium can be reduced, and the dispersibility and buoyancy can be further improved. Furthermore, the specific gravity of the temperature-sensitive magnetic fluid particles 1 can be adjusted by adjusting the volume of the air bubbles 12 inside the skeleton part 11.

In the above embodiment, the temperature-sensitive magnetic particles 10 are directly included in the skeleton 11, but as shown in FIG. 8, the temperature-sensitive magnetic particles 110 may be dispersed in a predetermined fluid. It is also possible to include it in the skeleton part 11 in a state where it is closed. The temperature-sensitive magnetic fluid particles 101 shown in FIG. 8 include an internal fluid 113 in which temperature-sensitive magnetic particles 110 made of ferromagnetic material are dispersed, and a skeleton portion 11 containing the internal fluid 113 and made of a non-magnetic material. That is, the skeleton part 11 has a plurality of spaces in which the internal fluid 113 is accommodated. Also in this modification, the skeleton portion 11 has a plurality of air bubbles 12 inside.

In this modification, the temperature-sensitive magnetic particles 110 are made of magnetite, the internal fluid 113 is made of kerosene, and the skeleton portion 11 is made of polylactic acid. In the temperature-sensitive magnetic fluid particles 101, the particle size of the temperature-sensitive magnetic particles 110 is about 10 nm, and the outer diameter of the space in which the internal fluid 113 is accommodated is about 100 nm. The particle size is about 10 μm. Note that the temperature-sensitive magnetic particles 110 can be made of any material and have any particle diameter as long as they are ferromagnetic, the skeleton 11 can be made of any material and have any outer diameter as long as they are non-magnetic, and the material and diameter of the internal fluid 113 can be determined as desired. The outer diameter of the space in which the internal fluid 113 is accommodated is also arbitrary.

The temperature-sensitive magnetic fluid particles 101 are manufactured by dispersing the temperature-sensitive magnetic fluid in which the temperature-sensitive magnetic particles 110 are dispersed in the skeleton solution 20 using the internal fluid 113 as a dispersion medium in the primary dispersion process of the embodiment. can do. In this temperature-sensitive magnetic fluid particle 101 as well, the degree of freedom in selecting a dispersion medium can be dramatically improved, and the redispersibility of the temperature-sensitive magnetic fluid particle 101 after pressure release can be improved. In this modification, the conventional temperature-sensitive magnetic fluid in which temperature-sensitive magnetic particles 102 with a relatively small particle size are dispersed is used as is, and the temperature-sensitive magnetic fluid particles 101 with a relatively large particle size are used as is. It is possible to do so.

Furthermore, as shown in FIG. 9, for example, the skeleton 11 can contain a material other than the temperature-sensitive magnetic particles 10, and the temperature-sensitive magnetic fluid particles 201 can have multiple functions. The temperature-sensitive magnetic fluid particle 201 in FIG. 9 includes a plurality of temperature-sensitive magnetic particles 10, a plurality of latent heat storage materials 214, and a skeleton portion 11 that includes each temperature-sensitive magnetic particle 10 and each latent heat storage 214. . The latent heat storage material 214 undergoes a phase change between a solid phase and a liquid phase at a predetermined melting point. As the latent heat storage material 214, paraffin, cyclohexane, hexadecane, etc. can be used, for example. That is, the skeleton part 11 has a plurality of spaces in which each temperature-sensitive magnetic particle 10 and each latent heat storage material 214 are accommodated. Note that, in the temperature-sensitive magnetic fluid particles 201, no air bubbles are formed inside the skeleton portion 11.

The temperature-sensitive magnetic fluid particles 201 can be manufactured by dispersing the latent heat storage material 214 together with the temperature-sensitive magnetic particles 10 in the skeleton solution 20 in the primary dispersion process of the embodiment. In this temperature-sensitive magnetic fluid particle 201 as well, the degree of freedom in selecting a dispersion medium can be dramatically improved, and the redispersibility of the temperature-sensitive magnetic fluid particle 201 after pressure release can be improved. In addition, a latent heat storage function is imparted to the temperature-sensitive magnetic fluid particles 201, and heat storage and transport becomes possible by using the temperature-sensitive magnetic fluid in which the temperature-sensitive magnetic fluid particles 201 are dispersed.

Here, particles for a temperature-sensitive magnetic fluid were actually produced, and the rheological properties of a temperature-sensitive magnetic fluid using the particles and a conventional temperature-sensitive magnetic fluid were compared. In comparing the rheological properties, the temperature-sensitive magnetic fluids of the example and the temperature-sensitive magnetic fluid of the comparative example were prepared so that the temperature-sensitive magnetic particles of the same particle size were contained in the same amount. FIG. 10(a) shows a graph of the shear rate and shear stress of the temperature-sensitive magnetic fluid of the example, and FIG. 10(b) shows a graph of the shear rate and shear stress of the temperature-sensitive magnetic fluid of the comparative example. As shown in FIGS. 10(a) and 10(b), it was confirmed that the peak value of shear stress in the example was lower than that of the comparative example, and the dispersibility of particles in the dispersion medium was increased. .

Furthermore, when the flow field of the temperature-sensitive magnetic fluid of the example was observed in the microchannel, it was confirmed that the clusters moved as if rubbing against the wall surface, and the clusters swayed and disturbed the flow. In this way, it is understood that while in a normal fluid, the velocity on the wall surface is zero, in the temperature-sensitive magnetic fluid of the example, a flow velocity occurs on the wall surface and disturbance occurs. Therefore, the temperature-sensitive magnetic fluid of the present invention can be used as a refrigerant with a high heat transfer coefficient.

Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are essential for solving the problems of the invention.

1 Particles for temperature-sensitive magnetic fluid 2 Temperature-sensitive magnetic fluid 3 Dispersion medium 10 Temperature-sensitive magnetic particles 11 Skeletal portion 12 Bubbles 20 Skeletal solution 21 Primary dispersion 22 External phase solution 23 Secondary dispersion 100 Channel 101 For temperature-sensitive magnetic fluid Particles 110 Temperature-sensitive magnetic particles 113 Internal fluid 201 Particles for temperature-sensitive magnetic fluid 214 Latent heat storage material

Claims (9)

A plurality of temperature-sensitive magnetic particles made of ferromagnetic material,
a skeleton part made of a non-magnetic material and containing the plurality of temperature-sensitive magnetic particles ;
The skeleton part is a temperature-sensitive magnetic fluid particle containing a plurality of latent heat storage materials . The particle for temperature-sensitive magnetic fluid according to claim 1 , wherein the skeleton has a plurality of bubbles inside . The temperature-sensitive magnetic fluid particles according to claim 2, wherein the particle size of the temperature-sensitive magnetic fluid particles is 1 μm or more and 1 mm or less . 4. The temperature-sensitive magnetic fluid particles according to claim 3, wherein the particle size of the temperature-sensitive magnetic fluid particles is 100 times or more and 1000 times or less the particle size of the temperature-sensitive magnetic particles. Particles for temperature-sensitive magnetic fluid according to any one of claims 1 to 4,
A temperature-sensitive magnetic fluid comprising: a dispersion medium in which the temperature-sensitive magnetic fluid particles are dispersed. A method for producing particles for temperature-sensitive magnetic fluid according to claim 1 , comprising:
The skeleton part is made of plastic,
a solution generation step of dissolving a polymer, which is a raw material for the skeleton, in an organic solvent to generate a skeleton solution;
a primary dispersion step of dispersing the temperature-sensitive magnetic fluid containing the temperature-sensitive magnetic particles or the temperature-sensitive magnetic particles in the skeleton solution generated in the solution generation step to generate a primary dispersion;
a secondary dispersion step in which the primary dispersion produced in the primary dispersion step is dispersed in an external phase solution that is immiscible with the organic solvent to generate a secondary dispersion;
A skeleton part precipitation step of removing the organic solvent from the secondary dispersion liquid generated in the secondary dispersion process and precipitating the skeleton part in a state in which a plurality of the temperature-sensitive magnetic particles are encapsulated. Method for producing particles for temperature-sensitive magnetic fluid. A method for producing particles for temperature-sensitive magnetic fluid according to claim 2 , comprising:
The skeleton part is made of plastic,
a solution generation step of dissolving a polymer, which is a raw material for the skeleton, in an organic solvent to generate a skeleton solution;
a primary dispersion step of dispersing the temperature-sensitive magnetic fluid containing the temperature-sensitive magnetic particles or the temperature-sensitive magnetic particles in the skeleton solution generated in the solution generation step to generate a primary dispersion;
a secondary dispersion step in which the primary dispersion produced in the primary dispersion step is dispersed in an external phase solution that is immiscible with the organic solvent with air mixed therein by stirring to generate a secondary dispersion;
a skeleton part precipitation step in which the organic solvent is removed from the secondary dispersion liquid generated in the secondary dispersion step, and the skeleton part is precipitated in a state in which the plurality of temperature-sensitive magnetic particles and the air bubbles are encapsulated; A method for producing particles for a temperature-sensitive magnetic fluid, comprising: In the skeleton precipitation step, the secondary dispersion is maintained at a temperature near the boiling point of the organic solvent for a predetermined period of time, and the organic solvent in the secondary dispersion is dissolved in the external phase solution to form the external phase solution. The method for producing particles for a temperature-sensitive magnetic fluid according to claim 6 or 7, wherein the particles are volatilized from a liquid. A method for producing a temperature-sensitive magnetic fluid according to claim 5, comprising:
The skeleton part is made of plastic,
a solution generation step of producing a skeleton solution by dissolving the polymer, which is a raw material for the skeleton, in an organic solvent that is immiscible with the dispersion medium;
a primary dispersion step of dispersing the temperature-sensitive magnetic fluid containing the temperature-sensitive magnetic particles or the temperature-sensitive magnetic particles in the skeleton solution generated in the solution generation step to generate a primary dispersion;
a secondary dispersion step of dispersing the primary dispersion generated in the primary dispersion step in the dispersion medium to generate a secondary dispersion;
skeletal part precipitation in which the organic solvent is removed from the secondary dispersion liquid produced in the secondary dispersion step, and the skeletal part is precipitated in the dispersion medium with a plurality of the temperature-sensitive magnetic particles encapsulated therein; A method for producing a temperature-sensitive magnetic fluid, comprising:

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