Energy absorption and release material

Abstract

The present invention provides a material having a higher electromagnetic wave absorbing capability than prior art electromagnetic wave absorbing materials. The present invention relates to an energy absorbing and releasing material characterized by comprising titanium oxide having, in the L*a*b* color system, an L* value satisfying 50 ≤ L* ≤ 90, and a b* value satisfying b* < 0.

Description

[Technical Field]

[0001] The present invention relates to an energy absorbing and releasing material. [Background technology]

[0002] In recent years, the use of electromagnetic waves ranging from microwaves to millimeter waves (GHz band) has rapidly expanded, and they are now used in a wide variety of applications, including personal computers, mobile phones, various electronic devices using wireless LAN, microwave ovens, satellite broadcasting, and radar. However, concerns have arisen about the effects of the use of various electromagnetic waves in daily life on the human body. Furthermore, radars used for purposes such as automobile collision prevention and autonomous driving have been found to malfunction due to external electromagnetic waves. As one way to resolve these issues, research has been conducted into materials that absorb electromagnetic waves. Technologies have been reported that use dielectric materials such as titanium oxide and barium titanate, magnetic materials such as iron oxide, and carbon, mixed with various resins and fibers, to absorb electromagnetic waves and block unwanted electromagnetic waves (see Patent Documents 1 and 2). Furthermore, temperature-regulating materials that utilize materials with electromagnetic wave absorption capabilities to heat food at a uniform temperature in an electromagnetic microwave oven have been reported (see Patent Documents 3 to 5). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4859791 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-169804 [Patent Document 3] Japanese Patent Application Publication No. 2019-102665 [Patent Document 4] Japanese Patent Application Publication No. 2018-189250 [Patent Document 5] Japanese Patent Application Laid-Open No. 2013-239459 Summary of the Invention [Problem to be solved by the invention]

[0004] As mentioned above, electromagnetic wave absorbers have been proposed as a way to prevent the harmful effects of electromagnetic waves on the human body and equipment, and methods have also been proposed for utilizing the properties of electromagnetic wave absorbers to regulate temperature. However, carbon, a dielectric electromagnetic wave absorber, can absorb excessive electromagnetic waves and ignite, or can deteriorate the properties of surrounding resins and fiber materials due to excessive heat generation and heat storage. Iron oxide, a magnetic electromagnetic wave absorber, has insufficient electromagnetic wave absorption capacity due to its reduced relative permeability in the GHz band. As such, conventional electromagnetic wave absorbers are not sufficient in terms of performance. Furthermore, electromagnetic wave absorbers are sometimes mixed into resins, fiber materials, etc., and when mixed in large amounts for the purposes of electromagnetic wave blocking or temperature regulation, the properties of the resins, fiber materials, etc. may change, potentially deteriorating various properties. For this reason, there is a demand for materials with high electromagnetic wave absorption capacity that can exert sufficient electromagnetic wave absorption capacity even when used in small amounts.

[0005] In view of the above-mentioned current situation, an object of the present invention is to provide a material having a higher electromagnetic wave absorbing ability than conventional electromagnetic wave absorbing materials. [Means for solving the problem]

[0006] The present inventors have investigated materials that have higher electromagnetic wave absorption capacity than conventional electromagnetic wave absorbers, and have found that * a * b * L in color space * value and b * It was found that titanium oxide having a value within a predetermined range has excellent properties as an energy absorption / release material for electromagnetic waves, since it rapidly increases in temperature when irradiated with electromagnetic waves, has excellent electromagnetic wave absorption ability, and also rapidly releases the absorbed energy as heat.

[0007] That is, the present invention is * a * b * L in color space * Value 50≦L * ≦90 and b* The value is b * The energy absorption / release material is characterized by being made of titanium oxide having a refractive index of <0.

[0008] The titanium oxide is preferably a titanium suboxide represented by the composition formula TiOx (x is a number satisfying 1.8≦x<2).

[0009] The energy absorption / release material has a complex relative permittivity of 20 or more at a frequency of 1 GHz and a dielectric loss tangent of 3.0×10 -2 It is preferable that this is equal to or greater than this.

[0010] The energy absorbed by the energy absorbing / releasing material is preferably electromagnetic waves.

[0011] The present invention also relates to a resin material containing the energy absorbing / releasing material of the present invention and a resin.

[0012] The present invention also relates to a fiber material comprising the energy absorbing and releasing material of the present invention and organic and / or inorganic fibers.

[0013] The present invention also relates to a ceramic material comprising the energy absorption / release material of the present invention and a ceramic. [Effects of the Invention]

[0014] The energy absorption / release material of the present invention heats up faster than conventional titanium oxides or iron oxides when irradiated with electromagnetic waves in the GHz band, and does not ignite like carbon. Because it also has a fast heat dissipation rate, it can be suitably used as an electromagnetic wave absorber that exhibits high electromagnetic wave absorption properties, or as a temperature adjustment material in environments heated by energy such as electromagnetic waves. DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description and can be modified and applied as appropriate within the scope that does not change the gist of the present invention.

[0016] 1. Energy absorption and release materials The energy absorption / release material of the present invention has excellent energy absorption properties, such as quickly absorbing energy from electromagnetic waves and heating, and also has excellent heat dissipation properties, such as releasing energy as heat, and therefore can be suitably used as an electromagnetic wave absorption material or a temperature regulating material. The energy absorption / release material of the present invention is L * a * b * L in color space * Value 50≦L * ≦90 and b * The value is b * It is made of titanium oxide with a lightness of L<0. * The larger the value, the brighter the color and the closer it is to white. * The smaller the value, the darker the color becomes, and the closer it is to black. * The larger the positive value, the closer to yellow the color becomes, and conversely, the smaller the negative value, the closer to blue the color becomes. * Value 50≦L * ≦90 and b * The value is b * It has been discovered that a bluish color having a refractive index of <0 has excellent energy absorption and release capabilities. Titanium dioxide L * The value is 55≦L * It is preferable that b is ≦85. * The value is b * Preferably <-2. Titanium dioxide L * value, b * The value can be measured by the method described in the Examples below.

[0017] The titanium oxide is preferably a titanium suboxide represented by the composition formula TiOx (x is a number in the range of 1.8≦x<2). When the titanium oxide is such a titanium suboxide, it has a better energy absorption / release ability. The above x is more preferably a number satisfying the condition 1.9≦x<2, and even more preferably a number satisfying the condition 1.95≦x<2. The value of x in the composition TiOx of the titanium suboxide powder can be calculated by the method shown in the examples below.

[0018] The energy absorption / release material of the present invention has a complex relative permittivity of 20 or more at a frequency of 1 GHz and a dielectric loss tangent of 3.0×10 -2 It is preferable that this is equal to or greater than this. If the energy absorption / release material of the present invention has such properties, it will have excellent electromagnetic wave absorption ability and also excellent ability to convert the absorbed electromagnetic wave energy into thermal energy and release it, making it more suitable as an electromagnetic wave absorption material. The real part of the complex relative permittivity of the energy absorbing and releasing material of the present invention at a frequency of 1 GHz is more preferably 30 or more, and even more preferably 40 or more. The dielectric loss tangent of the energy absorption / release material of the present invention is more preferably 5.0×10 -2 More preferably, it is 1.0 × 10 -1 That's all. The real part of the complex relative permittivity and the dielectric loss tangent at a frequency of 1 GHz of the energy absorbing / releasing material can be measured by the method described in the examples below.

[0019] The titanium oxide has a specific surface area of ​​0.1 to 100 m 2 / g. If such a specific surface area is used, the material will be superior as an energy absorption / release material. The specific surface area of ​​titanium oxide is more preferably 0.5 to 50 m 2 / g, and more preferably 0.5 to 40 m 2 / g. The specific surface area of ​​titanium oxide can be measured by the method described in the examples below.

[0020] The titanium oxide has a volume resistivity of 1.0 x 10 -2 It is preferable that the volume resistivity is Ω·cm or more. A high volume resistivity is advantageous in converting the absorbed electromagnetic wave energy into heat and releasing it. The volume resistivity is more preferably 1.0×10 1 Ω·cm or more, and more preferably 1.0×103 Ω·cm or more. Particularly preferably, it is 1.0×10 6 Ω·cm or more. The volume resistivity of titanium oxide can be measured by the method described in the examples below.

[0021] As described above, the energy absorption / release material of the present invention has excellent energy absorption properties, quickly absorbing energy such as electromagnetic waves and heat to be heated, and also has excellent heat dissipation properties, releasing energy as heat. Therefore, it can be suitably used as an electromagnetic wave absorption material, a temperature regulating material, and also as a material for an electromagnetic wave heating catalyst. Thus, in one preferred embodiment of the present invention, the energy to be absorbed is electromagnetic waves.

[0022] The energy absorbing / releasing material of the present invention has a high real part of complex dielectric constant and a high dielectric loss tangent, and thus has a high electron storage capacity. Furthermore, the energy absorbing / releasing material of the present invention has a lower volume resistivity than conventional titanium oxides, and is highly capable of conducting electrons from the outside to the energy absorbing / releasing material of the present invention and of conducting stored electrons to the outside. Therefore, the energy absorbing / releasing material of the present invention can be suitably used, for example, as an inorganic filler used in condensers, capacitors, target materials, magnetic memories, optical information recording media, charge storage memories, color filters, transfer belts, antenna substrates, etc., as an oxide semiconductor layer used in dye-sensitized solar cells and perovskite solar cells, as a positive electrode coating material for secondary batteries, and as a pre-dope material. Furthermore, the energy absorbing / releasing material of the present invention has a lower brightness than titanium oxide used as a white pigment and a high ability to rapidly dissipate heat, and therefore can be suitably used, for example, as a pigment, dye, or semiconductor encapsulant with a brightness lower than white.

[0023] The energy absorbing and releasing material of the present invention may be used alone or in combination with other materials such as resins, organic and / or inorganic fibers, metals, ceramics, and the like. Examples of resins that can be used include bismaleimide resin, epoxy resin, polyimide resin, polysulfone resin, polyamideimide resin, polyetherimide resin, polyethersulfone resin, polybenzimidazole resin, silicone resin, phenolic resin, polyester resin, polyvinyl ester resin, polyurethane resin, melamine resin, cyanate ester resin, isocyanate resin, polybenzoxazole resin, polyvinyl alcohol resin, and modified resins thereof. Examples of fibers that can be used include organic fibers such as cotton, silk, hemp, wool, nylon, vinylon, polyester fibers, acrylic fibers, vinylidene chloride fibers, acetate, and rayon; and inorganic fibers such as glass fibers and carbon fibers. Examples of metals that can be used include alkali metals, alkaline earth metals, rare earth metals, titanium group, earth metals, chromium group, manganese group, iron group, platinum group, copper group, zinc group, aluminum group, carbon group, nitrogen group, and oxygen group metals. Examples of ceramics include metal oxides, metal non-oxides, glass, and porcelain. The energy absorbing / releasing material of the present invention and materials using these in combination are also part of the present invention. That is, a resin material containing the energy absorbing / releasing material of the present invention and a resin, a fiber material containing the energy absorbing / releasing material of the present invention and organic and / or inorganic fibers, a material containing the energy absorbing / releasing material of the present invention and a metal, and a ceramic material containing the energy absorbing / releasing material of the present invention and a ceramic are all part of the present invention.

[0024] 2. Manufacturing method of energy absorption / release material The energy absorption / release material of the present invention is L * a * b * L in color space * Value 50≦L * ≦90 and b * The value is b * There are no particular limitations on the method for producing titanium oxide having a carbon content of <0, but it can be produced by a production method including a step of firing raw materials containing titanium dioxide (TiO2) in a reducing atmosphere.

[0025] The crystal structure of titanium dioxide used as the raw material is not particularly limited, and any of rutile, anatase, and brookite types can be used, and mixtures of these types are also acceptable.

[0026] The titanium dioxide used as the raw material is not particularly limited, but it is preferable that the specific surface area is 5 to 400 m 2 / g is preferred. By using a material with such a specific surface area, titanium oxide can be fired more efficiently in a reducing atmosphere. More preferably, the specific surface area is 10 to 300 m 2 / g, and more preferably, the specific surface area is 50 to 200 m 2 / g. The specific surface area of ​​titanium dioxide can be measured by the method described in the examples below.

[0027] The raw material may contain additives other than titanium dioxide, such as agglomeration inhibitors, reduction aids, dispersants, fluxes, moisture absorbents, oxygen absorbers, and heat-generating aids. Examples of agglomeration inhibitors that can be used include oxides of aluminum, silicon, zinc, yttrium, zirconium, niobium, molybdenum, indium, tin, and rare earth elements, with silicon dioxide being preferred.

[0028] When a mixture of two or more components (raw material mixture) is used as a raw material, the raw material mixture can be obtained by mixing the components using a conventional mixing method. The mixing method can be a dry method, a wet method, or both. Each raw material component may be used alone or in combination of two or more.

[0029] When the raw material is fired in a reducing atmosphere (also referred to as reduction firing), the raw material may be fired as is, or if the raw material contains a solvent, the solvent may be removed before firing. The reducing atmosphere is not particularly limited, and examples thereof include a hydrogen (H2) atmosphere, a carbon monoxide (CO) atmosphere, a nitrogen (N2) atmosphere, a mixed gas atmosphere of hydrogen and carbon monoxide and / or nitrogen, a mixed gas atmosphere of hydrogen and an inert gas, and an ammonia (NH3) atmosphere. Among these, a hydrogen atmosphere, a nitrogen atmosphere, or a mixed gas atmosphere of hydrogen and nitrogen is preferred because it allows the desired titanium oxide to be produced efficiently. Furthermore, the reducing atmosphere is preferably one in which a reducing gas is continuously injected and flowing into the reaction field (also referred to as a system) where the reduction is taking place.

[0030] The raw materials may be fired once or twice or more times. When firing twice or more times, it is preferable that all steps are performed in a reducing atmosphere (preferably a hydrogen atmosphere, a nitrogen atmosphere, or a mixed gas atmosphere of hydrogen and nitrogen).

[0031] The firing temperature is preferably 500 to 1200°C, although it depends on the conditions of the reducing atmosphere such as the hydrogen concentration. * a * b * L in color space * Value 50≦L * ≦90 and b * The value is b * Titanium oxide can be more efficiently obtained when the sintering temperature is less than 0. The firing temperature is more preferably 600 to 1150°C, and even more preferably 700 to 1100°C. In this specification, the firing temperature means the maximum temperature reached in the firing step.

[0032] The calcination time, i.e., the time for which the calcination temperature is maintained, also depends on the conditions of the reducing atmosphere, such as the hydrogen concentration, but is preferably, for example, 5 minutes to 100 hours. If the calcination time is within this range, the reaction proceeds more sufficiently, resulting in excellent productivity. It is more preferably 30 minutes to 48 hours, even more preferably 60 minutes to 24 hours, and particularly preferably 2 to 10 hours. When the temperature is lowered after the firing is completed, a gas other than hydrogen (for example, nitrogen gas) may be mixed or substituted.

[0033] The method for producing an energy absorption / release material of the present invention may include other steps, such as cooling the fired titanium suboxide and pulverizing the fired titanium suboxide, as long as it includes the step of firing a raw material containing titanium dioxide (TiO2) in a reducing atmosphere. [Example]

[0034] Specific examples are given below to explain the present invention in detail, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "wt%" mean "% by weight (% by mass)."

[0035] Example 1 Rutile-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "STR-100N", specific surface area 100 m 2 20 g of titanium dioxide (1 / g) was placed in an alumina boat, and the temperature was raised to 1100°C over 107 minutes in an atmospheric firing furnace while 100 vol% nitrogen was passed through at 400 ml / min. The temperature was maintained at 1100°C for 3 hours, and then the powder was allowed to cool naturally to room temperature to obtain the powder of Example 1, which was identified as titanium dioxide having a rutile structure in the XRD diffraction pattern measured by the method described below.

[0036] Example 2 Rutile-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "STR-100N", specific surface area 100 m 2 20 g of the powder (20 g / g) was placed in an alumina boat, and the boat was placed in an atmospheric firing furnace where 100 vol% hydrogen was passed through at 400 ml / min while the temperature was raised to 800°C over 77 minutes. The temperature was then maintained at 800°C for 6 hours, and the boat was then naturally cooled to room temperature to obtain the powder of Example 2, which was identified as titanium oxide with a rutile structure in the XRD diffraction pattern measured by the method described below.

[0037] Example 3 Anatase-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "SSP-25", specific surface area 270 m 215.8 g of titanium dioxide (trade name "Silica", manufactured by Sigma-Aldrich Co.) was dry-mixed with 15.8 g of titanium dioxide (trade name "Silica", manufactured by Sigma-Aldrich Co.), and the mixture was placed in an alumina boat. The mixture was heated to 800°C over 77 minutes in an atmospheric firing furnace while 100 vol% hydrogen was passed through at 400 ml / min, and then maintained at 800°C for 8 hours. The mixture was then allowed to cool naturally to room temperature, yielding a powder of Example 3, which was identified as titanium oxide having an anatase structure in the XRD diffraction pattern measured by the method described below.

[0038] Comparative Example 1 Rutile-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "STR-100N", specific surface area 100 m 2 20 g of the powder (1 / g) was placed in an alumina crucible, heated to 870°C in an electric furnace over 84 minutes, held at 870°C for 5 hours, and then naturally cooled to room temperature to obtain a powder of Comparative Example 1.

[0039] Comparative Example 2 Rutile-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "STR-100N", specific surface area 100 m 2 / g) was used.

[0040] Comparative Example 3 Anatase-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "SSP-25", specific surface area 270 m 2 3 g of the powder (100 vol. / g) was placed in an alumina boat, and the boat was heated to 1000°C over 97 minutes in an atmospheric firing furnace while 100 vol.% hydrogen was passed through at 300 ml / min. The boat was then held at 1000°C for 5 hours and then naturally cooled to room temperature to obtain a powder of Comparative Example 3.

[0041] Comparative Example 4 Rutile-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "STR-100N", specific surface area 100 m 2 7.9 g of titanium dioxide (1 / g) and 2.1 g of titanium hydride (manufactured by Toho Tech Co., Ltd., trade name "Titanium hydride powder TCH-450") were dry-mixed, then placed in an alumina boat and heated to 1100°C over 107 minutes in an atmospheric firing furnace while 100 vol% hydrogen was passed through at 400 ml / min. The temperature was then maintained at 1100°C for 3 hours, and the mixture was then naturally cooled to room temperature to obtain a powder of Comparative Example 4.

[0042] Comparative Example 5 Barium titanate (manufactured by Sakai Chemical Industry Co., Ltd., product name "BT-01") was used.

[0043] Comparative Example 6 Iron oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "iron(III) oxide") was used.

[0044] Comparative Example 7 Carbon (manufactured by Cabot Corporation, trade name "VULCAN XC-72R") was used.

[0045] The materials of Examples 1 to 3 and Comparative Examples 1 to 7 were subjected to various measurements and evaluations by the following methods. The results are shown in Table 1. <L * a * b * Lightness L in the color system * value, chromaticity a * value, b * Value> Using a colorimeter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SE2000"), * a * b * Lightness L in the color system * value, chromaticity a * value, b * The values ​​were measured. <Calculating the x value of titanium oxide composition formula TiOx> The x value in the composition formula of titanium oxide, TiOx, was calculated by measuring the change in weight before and after heat treatment according to the following procedure. A predetermined amount of titanium oxide powder to be measured was first dried in a dryer (Yamato Scientific Co., Ltd., constant temperature incubator, DKM600) at 100°C for 1 hour to remove adsorbed moisture. Approximately 1 g was then weighed into a magnetic crucible using an electronic balance (Shimadzu Corporation, analytical balance, ATX224). The powder was then heat-treated in an electric furnace (Nitto Scientific Co., Ltd., tabletop electric furnace, NHK-120H-II) at 900°C for 1 hour in an air atmosphere to convert it to a complete TiO2 (x = 2.00) state. After the heat treatment, the crucible was transferred to a glass desiccator and allowed to cool to room temperature before being reweighed. The weight increase before and after heat treatment corresponds to the amount of oxygen vacancies from TiO2. The formula of the titanium oxide before heat treatment was TiOx1, its weight was W1 (g), its weight after heat treatment was W2 (g), and the atomic weight of Ti was M. T , the atomic weight of O is M O When The number of moles of TiOx1 before heat treatment = W1 / (M T +x1M O ) Number of moles of TiO2 after heat treatment = W2 / (M T +2M O ) Since the number of moles of TiOx1 and TiO2 does not change before and after heat treatment, W1 / (M T +x1M O )=W2 / (M T +2M O ) Therefore, when we solve for x1, we get x1=(W1(M T +2M O )-W2M T ) / W2M O Using the above formula, x1 was calculated. Furthermore, to eliminate the influence of the weight change due to the heat treatment on the moisture adhering to the titanium oxide to be measured before the heat treatment, titanium oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "STR-100N", specific surface area 100 m) was used. 2 The powder previously heat-treated as described above was prepared as a standard powder, and the standard powder was again heat-treated as described above. The value of x1 in the titanium oxide composition formula TiOx1 was calculated from the weight increase before and after the heat treatment. STDand, with respect to the x1 value calculated by the above method for the powders of the Examples and Comparative Examples, multiply by 2 / x STD and used this as the x value in the composition formula TiOx of titanium oxide. Also, when the value after multiplying by 2 / x STD exceeds 2, it was regarded as the influence of excessively attached moisture and x = 2 was used.

[0046] <Real part of the complex relative permittivity and dielectric loss tangent at 1 GHz in powder state> For the measurement of the real part of the complex relative permittivity and dielectric loss tangent of the powder, measurements were carried out using a dielectric constant measuring device ADMS01Nc1 (manufactured by A&T Co., Ltd.) and an attached 1 GHz resonator. <Specific surface area (BET - SSA)> In accordance with the provisions of JIS Z8830 (2013), after heat - treating the sample in a nitrogen atmosphere at 200 °C for 60 minutes, the specific surface area (BET - SSA) was measured using a specific surface area measuring device (manufactured by Mountech Co., Ltd., trade name "Macsorb HM - 1220").

[0047] <X - ray diffraction pattern> Under the following conditions, a powder X - ray diffraction pattern was measured using an X - ray diffractometer (manufactured by Rigaku Corporation, trade name "RINT - TTR3"). X - ray source: Cu - Kα ray Measurement range: 2θ = 10 - 70° Scan speed: 5° / min Voltage: 50 kV Current: 300 mA

[0048] <Volume resistivity (also referred to as volume intrinsic resistance)> For the measurement of the volume resistivity of the powder, a powder resistivity measurement system MCP - PD51 type (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) was used. The powder resistivity measurement system consists of a powder press part by hydraulic pressure, a four - probe probe, and a high - resistance measuring device (manufactured by the same company, Loresta - GX MCP - T700). According to the following procedure, the value of the volume resistivity (Ω·cm) was determined. 1) Put the sample powder into a press jig (diameter 20 mm) equipped with a four - probe probe on the bottom surface and set it in the pressurizing part of the powder resistivity measurement system. 2) After the powder press section was pressurized to 20 kN, the powder thickness was measured with a digital caliper and the resistance value was measured with a high resistance measuring device. 3) The volume resistivity (Ω·cm) was calculated from the powder thickness and resistance value using the following formula. (Volume resistivity) = (Resistance value) x (Resistivity correction coefficient) x (Thickness)

[0049] <Heating rate, heat radiation rate> 0.5 g of each of the powders from the Examples and Comparative Examples was placed in an alumina crucible, and powder temperature 1 was measured using a radiation thermometer THI-300 (manufactured by Ichinen TASCO Corporation). The powder was then irradiated with 2.4 GHz electromagnetic waves at 600 W for 2 minutes using a single-function microwave oven IM-573 (manufactured by Iwatani Corporation), and powder temperature 2 was measured again. After allowing the powder to cool for another 2 minutes, powder temperature 3 was measured. The heating rate and heat dissipation rate were calculated from the measured temperatures and the following equations. (Heating rate [℃ / min])={(Powder temperature 2[℃])-(Powder temperature 1[℃])}÷2[min] (Heat release rate [℃ / min])={(Powder temperature 2[℃])-(Powder temperature 3[℃])}÷2[min]

[0050] [Table 1]

[0051] Furthermore, the materials of Example 1 and Comparative Example 7 were mixed with resin by the following method to produce resin moldings, which were then subjected to measurement of the real part of the complex relative permittivity at 10 GHz, the dielectric loss tangent, and evaluation of the radio wave absorption characteristics. The measurement and evaluation methods and results are as follows. <Real part of complex relative permittivity and dielectric loss tangent at 10 GHz for resin molded body> 4.37 g of the powder of Example 1 or Comparative Example 7, 3.70 g of epoxy resin (Epicron 850, manufactured by DIC Corporation), 2.81 g of a polyfunctional thiol epoxy resin curing agent (TMMP, manufactured by SC Organic Chemicals), and 0.04 g of imidazole (Curesol 2E4MZ, manufactured by Shikoku Chemical Industry Co., Ltd.) were placed in an ointment container and mixed using a stirring and degassing device (Awatori Rentaro ARE-310) at 2000 rpm for 5 minutes and degassing at 2200 rpm for 1 minute. The mixture was then poured into a Teflon mold measuring 60 mm in length, 10 mm in width, and 1 mm in depth. The resin was then cured using a heated hydraulic press (Toyo Seiki Seisakusho, product name Mini Test Press MP-WNH) at a set pressure of 0.5 MPa at 100 °C for 1 hour to prepare a resin test piece for complex dielectric constant measurement. The real part of the complex relative permittivity and the dielectric loss tangent at 10 GHz were measured for the prepared resin test pieces using a permittivity measuring device ADMS01Nc1 (manufactured by AET Corporation) and an attached 10 GHz resonator. The measured real part of the complex dielectric constant of Comparative Example 7 was 7, and the dielectric loss tangent was 1.8 × 10 -1 In contrast, the real part of the complex dielectric constant of Example 1 was 8, and the dielectric loss tangent was 4.4 × 10 -1 It was confirmed that the real part of the complex dielectric constant and the dielectric loss tangent were equal to or greater than those of Comparative Example 7.

[0052] <Radio wave absorption characteristics> 28.44 g of the powder of Example 1, or an amount equivalent to the bulk of the powder of Comparative Example 7, 10.00 g of epoxy resin (Epicron 850, manufactured by DIC Corporation), 7.6 g of a polyfunctional thiol epoxy resin curing agent (TMMP, manufactured by SC Organic Chemicals), and 0.1 g of imidazole (Curesol 2E4MZ, manufactured by Shikoku Chemicals Corporation) were placed in an ointment container, and the mixture was mixed using a stirring and degassing device (Awatori Rentaro ARE-310) at 2000 rpm for 5 minutes and then at 2200 rpm for 1 minute. The mixture was then poured into a mold measuring 100 mm long, 100 mm wide, and 1 mm deep. The resin was then cured using a heated hydraulic press (Mini Test Press MP-WNH, manufactured by Toyo Seiki Seisakusho, Ltd.) at a set pressure of 0.5 MPa at 100 °C for 1 hour to prepare a resin test piece for measuring electromagnetic heating and heat dissipation properties. The radio wave absorption characteristics of the fabricated specimens were measured at room temperature and 76 GHz using a PNA network analyzer N5227A (Keysight Technologies) by the free space method. The measured radio wave absorption properties were normalized with the value of Comparative Example 7 set to 100. The test piece prepared using the powder of Example 1 had a radio wave absorption property of 100, which was confirmed to be equivalent to that of Comparative Example 7.

[0053] As shown in Table 1, L * a * b * L in color space * Value 50≦L * ≦90 and b * The value is b * The titanium oxides of Examples 1 to 3, in which the ratio of r to r is <0, exhibited a high heating rate when irradiated with electromagnetic waves and a high subsequent heat dissipation rate. * value and b *The titanium oxides of Comparative Examples 1 to 4, which did not satisfy the value requirements, had slower heating rates when irradiated with electromagnetic waves and slower subsequent heat release rates than the titanium oxides of Examples 1 to 3. Furthermore, the titanium oxides of Examples 1 to 3 had faster heating rates when irradiated with electromagnetic waves and faster subsequent heat release rates than the barium titanate and iron oxide of Comparative Examples 5 and 6, which have traditionally been used as dielectric materials and magnetic materials. Furthermore, unlike the carbon of Comparative Example 7, no ignition was observed when irradiated with electromagnetic waves, and the subsequent heat release rate was also faster than that of Comparative Example 7. Furthermore, it was confirmed that the molded product of Example 1, in which the titanium oxide was mixed with a resin, had performance equivalent to that of a molded product in which carbon and a resin were mixed, in terms of the real part of the complex dielectric constant, the dielectric loss tangent, and the radio wave absorption characteristics. From these results, L * a * b * L in color space * Value 50≦L * ≦90 and b * The value is b * It was confirmed that titanium oxide with a valence of <0 has excellent properties as an energy absorption / release material for electromagnetic waves, heat, etc.

Claims

1. L ＊ a ＊ b ＊ L in color system ＊ Value 55≦L ＊ ≦90, and b ＊ The value is b ＊ An energy absorption / release material comprising titanium oxide having a molecular weight of <0.

2. 2. The energy absorption / release material according to claim 1, wherein the titanium oxide is a titanium suboxide represented by the composition formula TiOx (x represents a number in the range of 1.8≦x<2).

3. The real part of the complex relative permittivity at a frequency of 1 GHz is 20 or more, and the dielectric loss tangent is 3.0 x 10 －２ 3. The energy absorption / release material according to claim 1, wherein the energy absorption / release material is the above-mentioned.

4. 4. The energy absorption / release material according to claim 1, wherein the energy to be absorbed is electromagnetic waves.

5. A resin material comprising the energy absorbing / releasing material according to any one of claims 1 to 4 and a resin.

6. A fiber material comprising the energy absorbing / releasing material according to any one of claims 1 to 4 and organic and / or inorganic fibers.

7. A ceramic material comprising the energy absorption / release material according to any one of claims 1 to 4 and ceramics.

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