JP7357200B2 - Titanium oxide material, heat storage/dissipation device, and method for producing titanium oxide material - Google Patents

Description

The present invention relates to a titanium oxide-based material, a heat storage/dissipation device, and a method for manufacturing a titanium oxide-based material. More specifically, the present invention relates to a titanium oxide material, a heat storage/dissipation device including the titanium oxide material, and a method for manufacturing the titanium oxide material.

Trititanium pentoxide undergoes a phase transition between solid phase and solid phase when heated, and absorbs heat accordingly. Trititanium pentoxide can be used as a heat storage/radiation material by utilizing the heat absorption property due to this solid phase-solid phase transition (Patent Document 1).

International Publication No. 2015/050269

The inventors investigated the use of various forms of trititanium pentoxide and attempted to develop a device that utilizes the endothermic properties of particulate trititanium pentoxide.

However, as the inventors proceeded with the development, it became clear that the amount of heat absorbed by the phase transition of particulate trititanium pentoxide was low, making it difficult to obtain a device with stable heat storage and release functions.

An object of the present invention is to provide a titanium oxide material containing trititanium pentoxide particles and easily exhibiting good heat absorption properties, a heat storage/dissipation device including the titanium oxide material, and a method for producing the titanium oxide material. That's true.

A titanium oxide-based material according to one embodiment of the present disclosure contains trititanium pentoxide particles. The trititanium pentoxide particles have a phase transition temperature that causes a phase transition between solid phase and solid phase, and have a median diameter D50 of 3 μm or more.

A heat storage/dissipation device according to one aspect of the present disclosure includes the titanium oxide-based material.

A method for producing a titanium oxide material according to one embodiment of the present disclosure is a method for producing a titanium oxide material containing trititanium pentoxide particles, and includes a step of pulverizing bulk trititanium pentoxide.

According to the titanium oxide-based material and the heat storage/dissipation device of the present disclosure, it contains trititanium pentoxide particles and tends to exhibit good heat absorption characteristics.

According to the method for producing a titanium oxide material of the present disclosure, a titanium oxide material containing trititanium pentoxide particles and easily exhibiting good endothermic properties can be obtained.

FIG. 1 is a graph showing an example of the relationship between the temperature and the amount of heat absorbed when the titanium oxide-based material according to the present embodiment is heated and cooled. FIG. 2 is a graph plotting the amount of heat absorbed at each average particle size (median diameter D50) of trititanium pentoxide particles in the titanium oxide-based materials of Examples 1 to 6. FIGS. 3A to 3C are SEM images showing examples of the state of the trititanium pentoxide particles of Examples 1, 2 and 4 after pulverization. FIG. 3D is a SEM image showing an example of the state of the trititanium pentoxide particles of Example 6. 4A to 4F are graphs showing examples of particle size distributions of trititanium pentoxide particles of Examples 1 to 5 and Comparative Example 1. FIG. 5 is a schematic diagram illustrating an example of a heat storage/dissipation device according to one aspect of the present embodiment.

The titanium oxide-based material according to one aspect of the present embodiment contains trititanium pentoxide particles. The trititanium pentoxide particles have a phase transition temperature that causes a phase transition between solid phase and solid phase, and have a median diameter D50 of 3 μm or more. When the median diameter of the trititanium pentoxide particles is 3 μm or more, it has an endothermic property in that it absorbs heat as a result of phase transition due to heating, and further, after the endothermic state of trititanium pentoxide radiates heat, it absorbs heat when heated again. . Therefore, the titanium oxide-based material of the present embodiment tends to exhibit good endothermic properties even if it contains particles of trititanium pentoxide. Therefore, titanium oxide-based materials can be stably used as heat storage and radiation materials even when used in heat storage and radiation devices and the like that have stable heat storage and radiation functions.

The titanium oxide based material of this embodiment will be specifically explained.

Due to the difference in crystal structure, trititanium pentoxide has β-trititanium pentoxide (hereinafter also referred to as β phase), which has a β-type monoclinic crystal structure, and α-trititanium pentoxide, which has an α-type rectangular crystal structure. - trititanium pentoxide (hereinafter also referred to as α phase) and λ-trititanium pentoxide (hereinafter also referred to as λ phase) having a λ-type monoclinic crystal structure. Trititanium pentoxide particles undergo a phase transition to an α phase when the β phase is heated, and a phase transition to the β phase when the α phase is cooled. Furthermore, when the β phase of the trititanium pentoxide particles is heated again and then cooled, the particles similarly undergo a phase transition. In other words, the titanium oxide material containing trititanium pentoxide particles has thermoreversibility.

The trititanium pentoxide particles of this embodiment include a β phase, and as shown in the thermal behavior of the broken line shown in FIG. and absorbs the first amount of heat. When trititanium pentoxide particles undergo a phase transition at the first endothermic phase transition temperature, the α phase is further cooled to undergo a phase transition to the β phase, and then heated again, the thermal behavior shown by the solid line shown in FIG. As shown, the β phase undergoes a phase transition to the α phase at the second endothermic phase transition temperature, and absorbs the second endothermic amount. Further, it is preferable that the second endothermic amount of the trititanium pentoxide particles is larger than the first endothermic amount. In this case, the titanium oxide-based material can maintain a high amount of heat absorption even if it contains trititanium pentoxide particles, and therefore tends to exhibit good heat absorption characteristics.

Here, the "first endothermic phase transition temperature" is the temperature at which the β phase of the trititanium pentoxide particles undergoes a phase transition to the α phase for the first time upon heating. "Second endothermic phase transition temperature" means that the β phase of the trititanium pentoxide particles undergoes a phase transition to the α phase at least once by heating, and after being cooled and the phase transition occurs from the α phase to the β phase, heating is performed again. This is the temperature at which the phase transition occurs from the β phase to the α phase. In addition, the "first endothermic amount" refers to the amount by which the β phase of trititanium pentoxide particles draws an arbitrary baseline on a graph showing the thermal behavior based on DSC (differential scanning calorimetry) measurement of trititanium pentoxide. Sometimes, it refers to the amount of endotherm calculated from the endothermic curve when endothermic at the first phase transition temperature. The amount of heat absorbed is calculated from the endothermic curve when heat is absorbed at the second phase transition temperature when an arbitrary baseline is drawn on a graph showing thermal behavior. When the first endothermic phase transition temperature and the second endothermic phase transition temperature are not particularly distinguished, they are also simply referred to as "endothermic phase transition temperatures," and when the first endothermic amount and the second endothermic amount are not particularly distinguished. is also simply called "absorption amount". Note that the DSC measurement can be performed using an appropriate measuring device, and the measurement conditions may be, for example, the conditions presented in the examples below.

In this embodiment, the β phase of trititanium pentoxide particles before absorbing heat at the first endothermic phase transition temperature, and the phase transition of trititanium pentoxide particles after absorbing heat at the first endothermic phase transition temperature and passing through the α phase, dissipating heat and undergoing a phase transition. It has different endothermic properties from the β phase of trititanium particles. In the trititanium pentoxide particles of this embodiment, the β phase undergoes a phase transition at the second endothermic phase transition temperature, then undergoes a phase transition to the α phase, and then the α phase is further cooled and undergoes a phase transition to the β phase, and then again. When heated, the endothermic phase transition temperature and endothermic amount, for example, when the phase transition by heating and cooling is performed two or more times, are approximately the same as the second endothermic phase transition temperature and the second endothermic amount.

In this embodiment, the second endothermic phase transition temperature of the trititanium pentoxide particles is lower than the first endothermic phase transition temperature. The second endothermic phase transition temperature is, for example, 191° C. or lower. In this case, when heat is applied to the titanium oxide-based material to reach a relatively high temperature such as 200°C or higher, the trititanium pentoxide particles having the second endothermic phase transition temperature absorb heat from a lower temperature. can do.

The second endothermic amount of the trititanium pentoxide particles in the titanium oxide-based material of this embodiment is 20 J/g or more. Therefore, titanium oxide-based materials can exhibit good endothermic properties.

It is also preferable that the first endothermic amount of the trititanium pentoxide particles is 20 J/g or more. In this case, the titanium oxide-based material can have particularly excellent endothermic properties. Therefore, the titanium oxide-based material can be easily used as a heat storage/dissipation material without controlling its endothermic properties by heating it at a temperature exceeding the first endothermic phase transition temperature.

The second endothermic amount of the trititanium pentoxide particles is preferably larger than the first endothermic amount. In this case, the titanium oxide-based material can be suitably used as a heat storage/dissipation material having an excellent amount of heat absorption.

The endothermic properties of the trititanium pentoxide particles in the titanium oxide-based material as described above can be achieved by adjusting the particle size of the titanium pentoxide particles.

As already mentioned, the titanium oxide material according to this embodiment contains trititanium pentoxide particles. The median diameter D50 of the trititanium pentoxide particles is 3 μm or more. The median diameter D50 is calculated from the particle size distribution measured on a volume basis by a laser diffraction/scattering method, and is the average particle diameter at which the cumulative frequency in the particle size distribution is 50%. The median diameter D50 can be measured, for example, using a measuring device such as Microtrack particle size distribution measuring device (model number MT3000II) manufactured by Nikkiso Co., Ltd.

The median diameter D50 of the trititanium pentoxide particles is preferably 15 μm or more. When the median diameter D50 of the trititanium pentoxide particles is 15 μm or more, the first endothermic amount of the trititanium pentoxide particles is larger than when the median diameter is less than 15 μm. Therefore, titanium oxide-based materials can achieve a higher endothermic amount even if the trititanium pentoxide particles have not undergone a phase transition from the β phase to the α phase at the first endothermic phase transition temperature. It has endothermic properties. Therefore, titanium oxide-based materials are easy to use as heat storage and radiation materials. Further, in this case, when applying the titanium oxide-based material to a heat storage/dissipation device, for example, it is possible to prevent variations in thermal history from occurring. Note that the upper limit of the median diameter D50 of the trititanium pentoxide particles is preferably 500 μm or less, more preferably 100 μm or less.

Further, when the median diameter D50 of the trititanium pentoxide particles is 3 μm or more and less than 15 μm, the first endothermic amount is very small compared to the second endothermic amount. Therefore, a titanium oxide material containing trititanium pentoxide particles having a median diameter D50 of 3 μm or more and less than 15 μm has a high It can have an endothermic amount. Therefore, titanium oxide based materials can be applied according to the above-mentioned endothermic properties. For example, if titanium oxide-based materials with the above characteristics are used, resins containing thermosetting resin components such as epoxy resins and silicone resins that require heat treatment at temperatures exceeding the endothermic phase transition temperature twice or more can be used. The amount of heat applied to the material can be controlled during the first heating and second heating. In addition, when using the above titanium oxide-based material, it is possible to evaluate the first and second endothermic amounts (i.e., the first endothermic amount and the second endothermic amount) without using an optical analyzer, etc. It is also possible to use the present invention as a measurement system that can evaluate the size of trititanium pentoxide particles simply by measuring the calorific value of a titanium oxide material or a composition containing a titanium oxide material as a component. Further, when the median diameter D50 of the trititanium pentoxide particles is 3 μm or more and less than 15 μm, it is also possible to improve the processability when molding the titanium oxide-based material. The reason why the above endothermic characteristics are exhibited when the median diameter D50 is 3 μm or more and less than 15 μm is considered to be, for example, as follows. For example, in the process of reducing the particle size of trititanium pentoxide particles during the pulverization process described in the manufacturing method described below, trititanium pentoxide particles receive mechanical energy and thermal energy from their surroundings, resulting in disordered crystal lattices. , the proportion of the β phase that causes thermal oscillations decreases, and the relative amount of heat absorption decreases. However, after passing through the first endothermic phase transition temperature, it becomes an α phase, and when heat is subsequently released, it becomes a β phase in which the crystal lattice disorder has been restored, that is, it returns to a state in which it can absorb heat again. Therefore, it is considered that when the β phase is heated to a temperature exceeding the second endothermic phase transition temperature, the second endothermic amount can increase. It is also more preferable that the median diameter D50 of the trititanium pentoxide particles is 3 μm or more and 11 μm or less. The results of confirming the relationship between the particle size (median diameter D50) and endothermic properties of titanium oxide-based materials containing trititanium pentoxide particles will be presented in Examples below.

In this way, the titanium oxide-based material according to the present embodiment can have different endothermic properties depending on the particle size of the trititanium pentoxide particles, and can undergo repeated phase transitions accompanied by heat absorption and release by heating and cooling. It is also possible. Therefore, it can be suitably used as a heat storage and release material having a repeated heat absorption and release function. Further, the titanium oxide-based material can memorize a thermal history including the temperature and amount of heat received and received by heating and cooling.

The titanium oxide-based material according to the present embodiment may contain components other than the trititanium pentoxide particles having a median diameter D50 of 3 μm or more as described above, as long as the effects of the present disclosure are not impaired. For example, the titanium oxide-based material may contain trititanium pentoxide particles that undergo a phase transition to λ-trititanium pentoxide upon heating. Further, for example, the titanium oxide-based material may contain other oxides containing titanium, or may contain components other than oxides containing titanium.

In the above, the case where the titanium oxide-based material is applied as a heat storage/dissipation material has been described as an example, but the application is not limited to this, and it can be applied as an appropriate material depending on the purpose. For example, it can be applied as an optical material, a semiconductor material, It may also be used in electronic materials, etc.

[Method for manufacturing titanium oxide material]
A method for manufacturing a titanium oxide-based material according to the present embodiment will be described.

This is a method for producing a titanium oxide material containing trititanium pentoxide particles, and the method for producing a titanium oxide material includes a step of pulverizing bulk trititanium pentoxide. Therefore, the titanium oxide-based material can have heat absorbing and dissipating characteristics depending on the particle size of the trititanium pentoxide particles.

The method for pulverizing bulk trititanium pentoxide is not particularly limited, and examples thereof include a planetary ball mill, an attriter mill, a bead mill, and a hammer mill. The pulverization may be carried out either dry or wet. Note that the term "agglomerate" means a shape that is not particulate, and examples of the agglomerate include those having a maximum particle size of 0.5 mm or more.

Hereinafter, a case will be described using as an example a case where bulk trititanium pentoxide is pulverized using a wet ball mill. However, the method for producing titanium oxide-based materials is not limited to this.

First, bulk trititanium pentoxide having appropriate dimensions is prepared as a raw material. The bulk trititanium pentoxide used as a raw material may be synthesized by chemical reaction or the like, or may be commercially available. Although the shape and size of the bulk trititanium pentoxide are not particularly limited, for example, the particle size of each chunk of trititanium pentoxide may be 0.8 mm or more and 4.0 mm or less. The raw materials are placed in a container made of zirconia, for example, and then water is added.

Subsequently, zirconia balls for crushing are placed in the container, the container is covered, and the container is placed in a crushing device (for example, a planetary ball mill). The number, material, and dimensions of the balls may also be adjusted as appropriate. Examples of the crushing device include a planetary ball mill manufactured by Fritsch (model number P-5). By appropriately adjusting the rotation speed and processing time of the pulverizer, trititanium pentoxide as a raw material can be pulverized. The conditions for crushing can be, for example, a rotation speed of 150 rpm or more and 200 rpm or less. If the rotation speed is 150 rpm or more, bulk trititanium pentoxide particles can be efficiently crushed. Moreover, the processing time for pulverization can be 5 minutes or more and 120 minutes or less.

As a result, trititanium pentoxide particles having an appropriate particle size in the titanium oxide-based material are obtained. The average particle diameter (median diameter D50) of the obtained trititanium pentoxide particles is calculated from the results obtained by particle size distribution measurement, as already explained. The trititanium pentoxide particles obtained by the method for producing a titanium oxide-based material of the present embodiment can have an appropriate average particle size (median diameter D50) by being pulverized.

[Heat storage/dissipation device]
An overview of the heat storage/dissipation device 1 according to this embodiment will be explained.

The heat storage/dissipation device 1 includes the titanium oxide-based material described above. The heat storage/dissipation device 1 has a function of absorbing heat around the heat storage/dissipation device 1 . That is, the heat storage/dissipation device 1 of the present embodiment is capable of absorbing heat and can thereby store the absorbed heat, and therefore can be applied to devices such as a heat storage device that stores heat and a heat storage/dissipation device. In this case, the heat storage/dissipation device 1 can function as a heat absorption device. Specifically, the heat storage/dissipation device 1 is configured such that the temperature of the heat storage/dissipation device 1 increases due to the transfer of ambient heat, for example, and the titanium oxide-based material in the heat storage/dissipation device 1 reaches a temperature exceeding its phase transition temperature. Once reached, it absorbs heat. The heat storage/dissipation device 1 can then store the absorbed heat. As a result, the heat storage/dissipation device 1 uses the heat generated from the heat generating parts of the electronic components, electronic devices, electronic equipment, etc. around the heat storage/dissipation device 1 to raise the temperature of the electronic components, electronic devices, electronic equipment, etc. Even if the temperature rises, the heat storage/dissipation device 1 stores heat, thereby suppressing the surrounding temperature from rising to a high temperature. Therefore, the heat storage/dissipation device 1 can prevent the temperature of surrounding heat-generating components from rising too much (runaway due to heat generation, etc.).

It is also preferable that the heat storage/radiation device 1 has a function of radiating heat stored in the titanium oxide material. In this case, the heat storage/dissipation device 1 can function as a heat dissipation (heat generation) device. Therefore, the heat storage/dissipation device 1 can be applied to, for example, a heat supply device that requires heat supply. Examples of heat supply devices include, for example, a fluid heating device that heats fluid in an air conditioner installed in a vehicle, a fluid heating device that heats working fluid flowing in an internal combustion engine, and a fluid heating device that heats fluid in a fluid flow path of a semiconductor device, etc. Examples include heating devices. The heat dissipation of the heat storage/dissipation device 1 is carried out by cooling the α-phase trititanium pentoxide particles that have been brought into a heat storage state by applying heat to the titanium oxide-based material, and are cooled to a temperature higher than the temperature at which the trititanium pentoxide particles undergo a phase transition. It can be achieved with As mentioned above, alpha-phase trititanium pentoxide in a heat storage state can radiate the absorbed heat when cooled, but unless rapidly cooled, the heat absorbed at the phase transition temperature during heating will be released all at once. It's not a thing. The term "quenching" used herein refers to, for example, cooling at a cooling rate of 100° C./min or more.

When the trititanium pentoxide particles of the titanium oxide-based material in the heat storage/dissipation device 1 absorb heat and undergo a phase transition, physical properties may change. Therefore, the heat storage and release device 1 can detect whether the temperature around the heat storage and release device 1 has reached the phase transition temperature by detecting changes in the physical properties of the trititanium pentoxide particles. Therefore, the heat storage and release device 1 can also be used as a temperature sensor. Applicable. Furthermore, since the heat storage/dissipation device 1 absorbs heat at a phase transition temperature, it may be used as a target for detecting the amount of absorbed heat. In this case, it is possible to detect the amount of thermal energy that can be absorbed and released when a temperature change occurs, relative to the total amount of thermal energy that can be stored (endothermic amount) by the titanium oxide-based material. That is, the heat storage/dissipation device 1 can also be used as a calorie sensor. Note that the use of the heat storage and release device 1 is not limited to the above, and for example, the heat storage and release device 1 may be used as a sheet having a heat storage and release function.

A case in which the heat storage/dissipation device 1 functions, for example, as a sensor will be specifically described.

As already explained, since the heat storage/dissipation device 1 includes a titanium oxide-based material, the temperature change or the heat absorption amount changes based on the change in physical properties accompanying the phase transition between the solid phase and the solid phase of the trititanium pentoxide particles. can be detected. Therefore, the heat storage/dissipation device 1 can be used as a sensor element that functions as a sensor for detecting the temperature or the amount of heat absorbed, for example. In this case, the sensor element detects, for example, when the temperature of trititanium pentoxide particles exceeds the phase transition temperature, a discontinuous change in the physical properties of trititanium pentoxide particles due to phase transition, or a phenomenon that occurs due to this change. can be output.

When the heat storage/dissipation device 1 functions as a sensor element, the output of the sensor element includes electrical conductivity (electrical conductivity), color, magnetism (magnetic susceptibility), and volume change (specific gravity), which are physical properties that change with phase transition. change) or thermal conductivity (thermal conductivity).

Regarding electrical conductivity, in trititanium pentoxide, which is a titanium oxide-based material, the β phase is a semiconductor, and the λ phase and α phase are conductors. Therefore, the sensor element can output changes in electrical conductivity. Note that the sensor element has electrical conductivity, such as a change in voltage due to a change in electrical conductivity when a constant current is applied, and a change in current due to a change in electrical conductivity when a constant voltage is applied. It is also possible to output a phenomenon that occurs as a result of a change in .

Regarding the color, for example, β-trititanium pentoxide is red or reddish-brown, and λ-trititanium pentoxide is black-blue or blue. Therefore, the sensor element can output a color change due to phase transition of trititanium pentoxide particles of the titanium oxide-based material.

Regarding magnetism, β-trititanium pentoxide is non-magnetic, while α-trititanium pentoxide and λ-trititanium pentoxide are paramagnetic. Therefore, the sensor element can output a change in magnetism due to phase transition of trititanium pentoxide particles of the titanium oxide-based material.

Regarding thermal conductivity, trititanium pentoxide particles, which are titanium oxide based materials, change their specific heat due to phase transition, so for example, changes in thermal conductivity and thermal diffusivity based on changes in specific heat can be output. Good too.

Further, regarding volume, since a volume change may occur during a phase transition of trititanium pentoxide particles of a titanium oxide-based material, changes in physical properties based on the volume change or specific gravity change may be output.

Note that the output of the sensor element is not limited to the above. Moreover, the output explained above is not limited to the case where the heat storage/dissipation device 1 functions as a sensor element, but may be the output of the heat storage/dissipation device 1 itself.

The sensor element includes, for example, a molded body containing a titanium oxide-based material. The molded body only needs to contain the trititanium pentoxide particles described above, and the molded body may contain components other than trititanium pentoxide as necessary, as long as they do not impede the intended use of the sensor element. . Components other than trititanium pentoxide include, for example, a resin component that functions as a binder. Therefore, the molded body may be made from a composition prepared by blending a titanium oxide-based material with a resin component or the like. The molded body can have an appropriate shape. For example, a titanium oxide based material can be molded with a molding machine to obtain a cylindrical molded body, but the molded body is not limited thereto. The dimensions of the sensor element may be adjusted as appropriate depending on the application. It is also preferable that the shape of the molded body is sheet-like. That is, it is also preferable that the heat storage/dissipation device 1 is sheet-shaped. Note that the case where the heat storage/dissipation device 1 is sheet-shaped will be described in detail later.

The sensor element may include an electrode electrically connected to the molded body. The sensor element includes, for example, two electrodes, and the electrodes and the molded body are stacked so that the molded body is interposed between the two electrodes. When the sensor element includes electrodes, the sensor element can generate an output through the electrodes. Note that the sensor element itself does not include an electrode, and when obtaining an output from the sensor element, the electrode may be electrically connected to the sensor element.

The electrode is made of, for example, a metal, a conductive oxide, a carbon material, or a conductive polymer. Examples of the metal include Al, Ag, Au, Cu, and Pt. Examples of the conductive oxide include indium tin oxide (ITO). Examples of the carbon material include graphite. Examples of the conductive polymer include polythiophene polymers, polyaniline polymers, and polyacetylene polymers.

Although the device for detecting the output of the sensor element is, for example, a device for detecting a change in electrical resistance value, it is not limited thereto. For example, a device for detecting the output of a sensor element includes a specific heat measuring device configured to detect changes in specific heat using an appropriate method, a spectral measuring device configured to detect color changes, and a magnetic measuring device configured to detect changes in magnetism. It may also be a specific gravity measuring device that measures changes in specific gravity.

In this way, the heat storage/dissipation device 1 according to the present embodiment can be used as a sensor for various uses that can respond to external stimuli in the surroundings. That is, the heat storage/dissipation device 1 can have a function as a sensor that detects temperature. For example, the heat storage/dissipation device 1 may be a single sensor element, or may be a device having a sensor function and other functions.

The application of the heat storage/dissipation device 1 will be explained by giving a specific example with reference to FIG. 5.

In FIG. 5, the heat storage/dissipation device 1 is formed in a sheet shape. Specifically, the heat storage/dissipation device 1 includes a sheet material 11 , a first electrode 12 , a second electrode 13 , and a detection section 16 . The sheet material 11 includes a titanium oxide material containing trititanium pentoxide particles having a median diameter D50 of 3 μm or more. The sheet material 11 may have one or both of heat absorption and heat radiation functions. The first electrode 12 is arranged on the first surface 11a of the sheet material 11. The second electrode 13 is arranged on the second surface 11b of the sheet material 11, which is opposite to the first surface 11a. The first electrode 12 and the second electrode 13 are electrically connected via the sheet material 11, and in FIG. 5, they are a pair of electrodes located on opposite sides of the sheet material 11. The detection unit 16 is electrically connected to the sheet material 11 via the first electrode 12 and the second electrode 13. Therefore, the heat storage/dissipation device 1 can detect heat from, for example, the heating element 4 outside or inside the heat storage/dissipation device 1 using the sheet material 11 .

The positions, shapes, and dimensions of the first electrode 12 and second electrode 13, which are a pair of electrodes, are not particularly limited. For example, both the first electrode 12 and the second electrode 13 may be arranged on the same surface of the sheet material 11 (for example, on the first surface 11a). Each of the first electrode 12 and the second electrode 13 may be the same as those described for the electrodes in the sensor element described above.

The detection unit 16 can detect the electrical characteristics of the sheet material 11 using the first electrode 12 and the second electrode 13. Thereby, for example, when the heat storage/dissipation device 1 and the heating element 4 that can generate heat are thermally connected, the heat storage/dissipation device 1 detects the electrical properties of the titanium oxide-based material in the sheet material 11 using the detection unit 16. By detecting the change in , it is possible to detect that the temperature reaching the phase transition temperature has been reached.

The detection unit 16 may be, for example, an electrical resistance detector having a function of detecting electrical resistance. In this case, the heat storage/dissipation device 1 can detect, by the detection unit 16, that the trititanium pentoxide in the sheet material 11 has reached the phase transition temperature by receiving the heat generated by the heating element 4, for example.

The heating element 4 is not particularly limited, and may be provided around or inside the heat storage/dissipation device 1 . The heating element 4 may be, for example, a heat-generating component that generates heat when supplied with power from an external power source or the like. A heat-generating component refers to an electronic component that converts a part of the energy given for driving into heat and releases the heat, for example. Heat generating components are not particularly limited, but specific examples of heat generating components include integrated circuits such as a central processing unit (CPU), power management IC (PMIC), power amplifier (PA), transceiver IC, and voltage regulator (VR). (IC); At least one type selected from the group consisting of light emitting elements such as light emitting diodes (LEDs), incandescent light bulbs, and semiconductor lasers; active elements such as field effect transistors (FETs); passive elements such as coils, capacitors, and resistors; including. Other examples of the heating element 4 include, specifically, home appliances, lighting equipment, medical equipment, electric furnaces, switchboards, water heaters, anti-fog equipment, anti-freeze equipment, and the like.

The detection unit 16 detects changes in physical properties such as thermal conductivity, magnetism, specific gravity, and wavelength characteristics, which may change during phase transition of trititanium pentoxide in the titanium oxide-based material in the sheet material 11, for example. There may be. In particular, it is preferable that the heat storage/dissipation device 1 detects a change in the physical properties of the titanium oxide-based material in either or both of the electrical conductivity and thermal conductivity. There is no particular restriction on the number of detection sections 16 in the heat storage/dissipation device 1, and the number of detection sections 16 may be one or more.

The heat storage/dissipation device 1 is not limited to the above configuration, and may include members having appropriate functions. For example, the heat storage/dissipation device 1 may include a control section 17 that controls the operation of the heat storage/dissipation device 1 or the heat generating body 4 based on the result detected by the detection section 16 . When the heat storage/dissipation device 1 includes the control unit 17, even if the heat storage/dissipation device 1 receives excessive heat from the heat generating body 4, for example, the operation of the heat storage/dissipation device 1 can be relaxed or stopped. Further, the heat storage/dissipation device 1 may include a support member (not shown) that supports the sheet material 11, the first electrode 12, and the second electrode 13, for example. The material, size, and shape of the support member are not particularly limited.

Hereinafter, specific examples of the present invention will be presented. However, the present invention is not limited only to the examples.

(1) Preparation of titanium oxide-based material Prepare trititanium pentoxide (product number 100097, minimum particle size 0.8 mm, maximum particle size 4.0 mm) manufactured by Merck Co., Ltd. as a raw material, and place the titanium pentoxide in a zirconia container. Trititanium oxide (10 to 20 g) and 150 g of water were added. 450 g of zirconia balls (ball diameter φ10 mm) were placed in a container, and the container was placed on a pulverizer and pulverized at a rotation speed of 150 to 200 rpm. As a grinding device, a planetary ball mill (manufactured by Fritsch, model number P-5) was used. The specific conditions for the pulverization treatment in each example are as follows.

In Example 1, trititanium pentoxide particles having a particle size distribution shown in FIG. 4A were obtained by treating 10 g of trititanium pentoxide at a rotation speed of 150 rpm for 120 minutes. Note that FIG. 3A is an SEM image obtained by measuring the trititanium pentoxide particles obtained in Example 1 using an SEM (scanning electron microscope). The median diameter D50 was 3.164 μm.

In Example 2, trititanium pentoxide particles having a particle size distribution shown in FIG. 4B were obtained by treating 20 g of trititanium pentoxide at a rotation speed of 150 rpm for 120 minutes. Note that FIG. 3B is an SEM image obtained by measuring the trititanium pentoxide particles obtained in Example 2 using an SEM (scanning electron microscope). The median diameter D50 was 5.713 μm.

In Example 3, trititanium pentoxide particles having a particle size distribution shown in FIG. 4C were obtained by treating 20 g of trititanium pentoxide at a rotation speed of 150 rpm for 30 minutes. The median diameter D50 was 10.21 μm.

In Example 4, trititanium pentoxide particles having a particle size distribution shown in FIG. 4D were obtained by treating 20 g of trititanium pentoxide at a rotation speed of 150 rpm for 15 minutes. Note that FIG. 3C is an SEM image obtained by measuring the trititanium pentoxide particles obtained in Example 3 using an SEM (scanning electron microscope). The median diameter D50 was 16.49 μm.

In Example 5, trititanium pentoxide particles having a particle size distribution shown in FIG. 4E were obtained by treating 20 g of trititanium pentoxide at a rotation speed of 200 rpm for 5 minutes. The median diameter D50 was 21.39 μm.

The trititanium pentoxide particles of Comparative Example 1 were obtained by treating the trititanium pentoxide (3 g) of Example 1 at a rotation speed of 200 rpm for 120 minutes. The trititanium pentoxide particles of Comparative Example 1 had a particle size distribution shown in FIG. 4F, and the median diameter D50 was 1.572 μm.

Furthermore, in Example 6, the size of particles as a sample used for measurement with a DSC device was measured without performing the pulverization treatment of Examples 1 to 5 above (see Table 1). Note that FIG. 3D is an SEM image obtained by measuring the trititanium pentoxide particles of Example 6 using an SEM (scanning electron microscope).

(2) Evaluation of titanium oxide-based materials The phase transition temperature and endothermic amount at the time of phase transition of the trititanium pentoxide particles of each Example and Reference Example obtained in (1) were measured by differential scanning calorimetry. For the measurement, a DSC device (model number DSC 220c, manufactured by Seiko Electronics Industries) was used, air gas was flowed at 100 mL/min, and the temperature was raised from room temperature to 300° C. at a heating rate of 10° C./min. After reaching 300°C, the temperature was lowered to room temperature at a cooling rate of 10°C/min. After reaching room temperature, the temperature was raised again from room temperature to 300°C at a rate of 10°C/min. The phase transition temperature and endothermic amount obtained from the results are shown in Table 1 below.

FIG. 1 is a graph showing the results of DSC measurement of the trititanium pentoxide particles of Example 4, where the broken line indicates the thermal behavior due to the first temperature increase and temperature decrease, and the solid line indicates the thermal behavior due to the second temperature increase and decrease. It shows thermal behavior due to temperature drop.

FIG. 2 is a graph plotting the endothermic amount calculated from the results obtained by DSC measurement with respect to the median diameter D50 of the trititanium pentoxide particles of each Example and Reference Example. The plot indicated by a white circle is the amount of heat absorbed during the first temperature increase, and the plot indicated by a black square is the amount of heat absorbed during the second temperature increase.

Table 1 shows the relationship between the median diameter D50 of the trititanium pentoxide particles of each Example and Reference Example, the amount of heat absorbed, and the phase transition temperature.

For the trititanium pentoxide particles of Examples 1 to 3, the amount of heat absorbed by the first temperature increase was small, but the amount of heat absorbed by the second temperature increase was significantly increased compared to the first temperature increase. In Examples 4 and 5, the amount of heat absorbed by the first temperature increase was 20 J/g or more, and the amount of heat absorbed by the second temperature increase further increased. Moreover, Example 5 exhibited the same thermal behavior as that of Example 4 shown in FIG.

In Comparative Example 1, no endotherm was observed due to the first temperature increase. In addition, although endotherm was observed due to the second temperature increase, the amount of endotherm was lower than in any of the examples.

As a result, when the median diameter D50 of trititanium pentoxide particles is 10 μm or less (Examples 1 to 3), the amount of heat absorbed in the first time is very small (approximately 0 J/g), but the amount of heat absorbed in the second time is very small (approximately 0 J/g). It was suggested that the amount of heat was 20 J/g or more. Furthermore, in Examples 1 to 5, it was suggested that as the median diameter D50 increases, the second phase transition temperature increases more than the first phase transition temperature. Furthermore, in Example 6, the phase transition temperature and endothermic amount did not change between the first and second times due to temperature increase, but the endothermic amount was 20 J/g or more in both the first and second times. Furthermore, in Comparative Example 1, the amount of heat absorbed during the first temperature increase was 0 J/g, so a phase transition temperature could not be obtained.

[summary]
As is clear from the above, the titanium oxide-based material of the first aspect of the present disclosure contains trititanium pentoxide particles. Trititanium pentoxide has a phase transition temperature at which it undergoes a phase transition between solid phase and solid phase, and has a median diameter D50 of 3 μm or more.

According to the first aspect, the titanium oxide-based material can undergo a reversible phase transition by heating and cooling, and can have an excellent amount of heat absorption. As a result, the titanium oxide-based material contains trititanium pentoxide particles and tends to exhibit good endothermic properties.

In the titanium oxide-based material of the second aspect, in the first aspect, the trititanium pentoxide particles include a β phase, and the β phase changes to an α phase at the first endothermic phase transition temperature by being heated. transfers and absorbs the first amount of endothermic heat. After the α phase is cooled and undergoes a phase transition to the β phase, when heated again, the α phase undergoes a phase transition to the α phase at a second endothermic phase transition temperature, and absorbs a second endothermic amount. The trititanium pentoxide particles have a second endothermic amount larger than the first endothermic amount.

According to the second aspect, the titanium oxide-based material can undergo a reversible phase transition by heating and cooling, and can have an excellent amount of heat absorption.

The titanium oxide material of the third aspect has a second endothermic amount of 20 J/g or more in the second aspect.

According to the third aspect, the titanium oxide-based material can undergo a reversible phase transition by heating and cooling, and can be suitably used as a heat storage/dissipation material having an excellent amount of heat absorption.

In the titanium oxide material of the fourth aspect, in the second or third aspect, the second endothermic phase transition temperature is lower than the first endothermic phase transition temperature.

According to the fourth aspect, the titanium oxide-based material can absorb heat even at a lower temperature than conventional trititanium pentoxide, and can also undergo a reversible phase transition by heating and cooling.
can.

In the titanium oxide material of the fifth aspect, in any one of the second to fourth aspects, the second endothermic phase transition temperature is 191° C. or lower.

According to the fifth aspect, heat that reaches a relatively high temperature, such as 200° C. or higher, can be absorbed from a lower temperature.

The titanium oxide-based material according to the sixth aspect has a first heat absorption amount of 20 J/g or more in any one of the second to fifth aspects.

According to the sixth aspect, the titanium oxide-based material can have particularly excellent endothermic properties.

In the titanium oxide material of the seventh aspect, in any one of the first to sixth aspects, the median diameter D50 of trititanium pentoxide particles is 15 μm or more.

According to the seventh aspect, when the median diameter D50 of the trititanium pentoxide particles is 15 μm or more, the titanium oxide-based material has a higher The amount of heat absorption can be achieved.

In the titanium oxide material according to the eighth aspect, in any one of the first to sixth aspects, the median diameter D50 of trititanium pentoxide particles is 3 μm or more and less than 15 μm.

According to the eighth aspect, when the median diameter D50 of trititanium pentoxide particles is 3 μm or more, trititanium pentoxide can have heat absorption and radiation properties as described above. In particular, when the median diameter D50 of the trititanium pentoxide particles is less than 15 μm, the thermal history of the phase transition temperature can be memorized by heating at a temperature exceeding the first phase transition temperature. On the other hand, in this case, trititanium pentoxide can have a high amount of endothermic heat in the second and subsequent heating by undergoing heat radiation.

The heat storage/dissipation device (1) according to the ninth aspect includes the titanium oxide-based material according to any one of the first to eighth aspects.

In the ninth aspect, it is possible to output a discontinuous change in physical properties of trititanium pentoxide particles of a titanium oxide-based material due to phase transition, or a phenomenon caused by this change.

In the ninth aspect, the heat storage/dissipation device (1) of the tenth aspect absorbs or radiates heat at the phase transition temperature of the titanium oxide-based material.

According to the tenth aspect, the heat storage/dissipation device (1) can detect that the temperature of the detection target exceeds the phase transition temperature, and can store a thermal history indicating that the temperature of the detection target has exceeded the phase transition temperature.

The heat storage/dissipation device (1) of the eleventh aspect detects a change in the physical properties of one or both of the electrical conductivity and thermal conductivity of the titanium oxide-based material in the ninth or tenth aspect.

In the eleventh aspect, it is possible to output a discontinuous change in physical properties of trititanium pentoxide particles in a titanium oxide-based material due to phase transition, or a phenomenon caused by this change. Further, it can be used as a sensor for various purposes that can respond to external stimuli in the surroundings.

A method for producing a titanium oxide-based material containing trititanium pentoxide particles according to a twelfth aspect includes a step of pulverizing trititanium pentoxide.

According to the twelfth aspect, trititanium pentoxide particles whose particle size is controlled are obtained.

1 Heat storage/dissipation device

Claims (11)

A titanium oxide-based material containing trititanium pentoxide particles,
The trititanium pentoxide particles have a phase transition temperature that causes a phase transition between solid phase and solid phase, and have a median diameter D50 of 3 μm or more,
The trititanium pentoxide particles include a β phase,
The β phase undergoes a phase transition to the α phase at a first endothermic phase transition temperature when heated, and absorbs a first amount of endothermic heat,
After the α phase is cooled and undergoes a phase transition to the β phase, when heated again, the α phase undergoes a phase transition to the α phase at a second endothermic phase transition temperature, and absorbs a second endothermic amount,
The second amount of heat absorption is larger than the first amount of heat absorption,
Titanium oxide material. the second endothermic amount is 20 J/g or more;
The titanium oxide material according to claim 1 . the second endothermic phase transition temperature is lower than the first endothermic phase transition temperature;
The titanium oxide material according to claim 1 or 2 . The second endothermic phase transition temperature is 191°C or less,
The titanium oxide material according to any one of claims 1 to 3 . the first endothermic amount is 20 J/g or more;
The titanium oxide material according to any one of claims 1 to 4 . The median diameter D50 of the trititanium pentoxide particles is 15 μm or more,
The titanium oxide material according to any one of claims 1 to 5 . The median diameter D50 of the trititanium pentoxide particles is 3 μm or more and less than 15 μm.
The titanium oxide material according to any one of claims 1 to 5 . comprising the titanium oxide-based material according to any one of claims 1 to 7 ,
Heat storage/dissipation device. absorbing or releasing heat at the phase transition temperature of the titanium oxide-based material;
The heat storage/dissipation device according to claim 8 . Detecting one or both of the physical properties of electrical conductivity and thermal conductivity caused by heating or cooling,
The heat storage/dissipation device according to claim 8 or 9 . A method for producing a titanium oxide material containing the trititanium pentoxide particles according to any one of claims 1 to 7 ,
Including the process of crushing bulk trititanium pentoxide,
A method for producing titanium oxide based materials.

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