Titanium dioxide-containing powder and method for producing titanium dioxide-containing powder

Abstract

This invention provides a dielectric material that combines excellent dielectric properties with a particle size suitable for mixing with resin materials. [Solution] A titanium dioxide powder is provided, wherein the powder has a dielectric constant of 14 or more at 10 GHz, a dielectric loss tangent of 0.0035 or less, and a specific surface area of ​​1.5 to 20 m². 2 Titanium dioxide-containing powder characterized by being / g

Description

[Technical Field]

[0001] This invention relates to titanium dioxide-containing powder and a method for producing titanium dioxide-containing powder. [Background technology]

[0002] With the recent advancements in information and communication technology, there is a growing demand for smaller, lighter, and faster communication equipment. Furthermore, to enable the transmission of larger volumes of information, high-frequency radio waves in the GHz band are increasingly being used. To miniaturize communication equipment operating in the high-frequency band, the substrate material used must possess excellent high-frequency transmission characteristics (low dielectric loss). Since dielectric loss is proportional to the product of frequency, the dielectric constant of the substrate (ε or Dk), and the dielectric loss tangent (tanδ or Df), reducing dielectric loss requires reducing the dielectric loss tangent of the substrate. Additionally, within the substrate, the wavelength of electromagnetic waves is 1 / (ε) 1 / 2 Because the time is shortened, the larger ε is, the smaller the substrate can be made. Therefore, for circuit boards of small devices used in the high-frequency range, materials with high dielectric constant and low dielectric loss tangent are required.

[0003] Substrate materials possessing the above dielectric properties include inorganic materials such as titanium oxide and titanates, and organic materials such as fluororesins. Of these, substrates made of dielectric materials have excellent ε and tanδ but have problems with processability, while substrates made of resin have excellent moldability, processability and tanδ but low ε. For this reason, composite substrates made by mixing dielectric materials into resin materials have been proposed to obtain a substrate that has the advantages of both. The dielectric materials described above are obtained by reducing the specific surface area of ​​titanates, which exhibit excellent dielectric properties, through high-temperature firing or special methods. However, particle aggregation occurs during the specific surface area reduction process, so in order to mix the dielectric material into a composite substrate, it is necessary to crush the aggregated particles generated by the specific surface area reduction process to adjust them to an appropriate particle size. The fine particles generated by crushing tend to be difficult to knead into the resin due to their high specific surface area, and the remaining coarse particles cause the surface roughness of the composite substrate after mixing the dielectric material to increase. To address this problem, methods have been disclosed for adjusting the particle size to an appropriate size by crushing for filling into the resin, and for performing both firing and crushing processes multiple times to suppress the decrease in dielectric properties and fluidity due to crushing (see Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5727224 [Patent Document 2] Japanese Patent Publication No. 2005-174711 [Overview of the project] [Problems that the invention aims to solve]

[0005] As described above, conventionally, aggregated particles generated during the low-specific surface area treatment of dielectric materials are crushed to adjust them to an appropriate particle size and mixed with resin materials to manufacture composite substrates. However, crushing aggregated particles deteriorates the dielectric properties of the dielectric material. For this reason, titanium oxide that achieves both excellent dielectric properties and a particle size suitable for mixing with resin materials has not yet been obtained.

[0006] In view of the above situation, the present invention aims to provide a dielectric material that achieves both excellent dielectric properties and a particle size suitable for mixing with resin materials. [Means for solving the problem]

[0007] The inventors investigated dielectric materials that possess both excellent dielectric properties and a particle size suitable for mixing with resin materials. They prepared a slurry containing titanium dioxide and a solvent, with an average particle size of secondary particles of 0.1 to 4 μm. They then obtained granulated particles from the slurry and fired the resulting particles at a temperature of 900 to 1250°C. They discovered that this process yielded a titanium dioxide-containing powder that possesses both excellent dielectric properties and a particle size suitable for mixing with resin materials, thus completing the present invention.

[0008] In other words, the present invention is as follows. [1] A powder containing titanium dioxide, The powder has a dielectric constant of 14 or higher at 10 GHz, a dielectric loss tangent of 0.0035 or lower, and a specific surface area of ​​1.5 to 20 m². 2 Titanium dioxide-containing powder characterized by being / g

[0009] [2] The titanium dioxide-containing powder according to [1], further characterized by containing strontium titanate.

[0010] [3] The titanium dioxide-containing powder according to [1] or [2], characterized in that the average particle size is 0.1 to 100 μm.

[0011] A resin composition characterized by containing a titanium dioxide-containing powder and a resin as described in any of [4][1] to [3].

[0012] [5] A method for producing titanium dioxide-containing powder, The manufacturing method comprises a first step of preparing a slurry containing titanium dioxide and a solvent, wherein the average particle size of the secondary particles is 0.1 to 4 μm, and The second step involves obtaining granulated particles from the slurry obtained in the first step, The process includes a third step in which the particles obtained in the second step are calcined at a temperature of 900 to 1250°C. A method for producing titanium dioxide-containing powder, characterized by the following:

[0013] [6] The first step is a step of preparing a slurry containing titanium oxide having an average particle diameter of secondary particles of 0.1 to 4 μm, a strontium-containing compound, and a solvent, which is characterized in the method for producing a titanium oxide-containing powder described in [5].

[0014] [7] The strontium-containing compound is at least one selected from the group consisting of strontium carbonate, strontium acetate, strontium nitrate, strontium oxalate, strontium hydrogen carbonate, and strontium titanate, which is characterized in the method for producing a titanium oxide-containing powder described in [6].

[0015] [8] The second step is carried out by spray-drying the slurry, which is characterized in the method for producing a titanium oxide-containing powder according to any one of [5] to [7]. [Advantages of the Invention]

[0016] The titanium oxide-containing powder of the present invention has excellent dielectric properties and a particle diameter suitable for mixing with a resin material, and thus can be suitably used as a dielectric material to be mixed with a resin and used. The method for producing a titanium oxide-containing powder of the present invention is a production method for obtaining such a titanium oxide-containing powder. [Brief Description of the Drawings]

[0017] [Figure 1] It is a diagram showing various analysis data for calculating the circularity of the titanium oxide-containing powder obtained in Example 12. [Figure 2] It is a diagram showing various analysis data for calculating the circularity of the titanium oxide-containing powder obtained in Comparative Example 2. [Figure 3] It is a diagram showing the measurement result of the particle size distribution of the titanium oxide-containing powder obtained in Example 6. [Figure 4] It is a diagram showing a photograph of the SEM observation result of the titanium oxide-containing powder obtained in Example 6. [Figure 5-1] It is a diagram showing a photograph of the SEM-EDS measurement result of the titanium oxide-containing powder obtained in Example 6. [Figure 5-2] This figure shows the spectrum obtained from SEM-EDS measurement of the titanium dioxide-containing powder obtained in Example 6. [Figure 6] This figure shows the XRD measurement results of the titanium dioxide-containing powder obtained in Example 6. [Figure 7] This figure shows the particle size distribution measurement results of the titanium dioxide-containing powder obtained in Example 11. [Figure 8] This figure shows a photograph of the SEM observation results of the titanium dioxide-containing powder obtained in Example 11. [Figure 9-1] This figure shows a photograph of the SEM-EDS measurement results of the titanium dioxide-containing powder obtained in Example 11. [Figure 9-2] This figure shows the spectrum obtained from SEM-EDS measurement of the titanium dioxide-containing powder obtained in Example 11. [Figure 10] This figure shows the XRD measurement results of the titanium dioxide-containing powder obtained in Example 11. [Modes for carrying out the invention]

[0018] The following describes preferred embodiments of the present invention in detail, but the present invention is not limited to the following description and can be modified and applied as appropriate without altering the essence of the invention.

[0019] 1. Titanium dioxide-containing powder The titanium oxide-containing powder of the present invention has a dielectric constant of 14 or higher at 10 GHz, a dielectric loss tangent of 0.0035 or lower, and a specific surface area of ​​1.5 to 20 m². 2 It is characterized by having a dielectric constant of / g. Such titanium oxide-containing powder with a high dielectric constant and low dielectric loss tangent can be suitably used as a material for circuit boards and the like in communication equipment used in the high-frequency band. The dielectric constant of titanium dioxide-containing powder at 10 GHz should be 14 or higher, but preferably 15 or higher. More preferably 18 or higher, and even more preferably 20 or higher. There is no particular upper limit to the dielectric constant of titanium dioxide-containing powder, but it is usually 30 or lower. The dielectric loss tangent of titanium oxide-containing powder at 10 GHz should be 0.0035 or less, but preferably 0.0030 or less. More preferably 0.0025 or less. There is no particular lower limit to the dielectric loss tangent of titanium oxide-containing powder, but it is usually a value of 0.0001 or higher. The dielectric constant and dielectric loss tangent of titanium dioxide-containing powder can be measured by the method described in the examples below.

[0020] The titanium dioxide-containing powder of the present invention has a specific surface area of ​​1.5 to 20 m². 2 The presence of [amount] / g makes it suitable for mixing into resin materials, but the specific surface area of ​​titanium dioxide-containing powder is 1.5 to 15 m². 2 It is preferable that the amount is / g. More preferably, 1.8 to 10m 2 / g, and more preferably 2-8m 2 The value is / g, and is particularly preferably 2.5 to 6m 2 It is / g. The specific surface area of ​​the titanium dioxide-containing powder can be measured by the method described in the examples below.

[0021] The titanium dioxide-containing powder of the present invention may contain titanium dioxide, and may or may not contain other components, but it is preferable that it further contains strontium titanate. As described later, by using a strontium-containing compound when manufacturing the titanium dioxide-containing powder, the resulting titanium dioxide-containing powder becomes spherical particles with a smoother surface, making it easier to mix uniformly with resin. Furthermore, by using a strontium-containing compound when manufacturing the titanium dioxide-containing powder, the resulting titanium dioxide-containing powder contains strontium titanate. When strontium titanate is included, its content is preferably 1 to 95% by mass, based on 100% by mass of the total titanium dioxide-containing powder. More preferably, it is 10 to 80% by mass, and even more preferably, 20 to 60% by mass.

[0022] When the titanium dioxide-containing powder of the present invention contains titanium dioxide and strontium titanate, it is preferable that it contains composite particles of titanium dioxide and strontium titanate. Including such composite particles makes the titanium dioxide-containing powder a material with a higher dielectric constant and lower dielectric loss tangent.

[0023] The particle size of the titanium dioxide-containing powder of the present invention is not particularly limited, and the optimal size can be selected and used depending on the application in which the titanium dioxide-containing powder is used and the required properties. For example, from the viewpoint of emphasizing the high dielectric constant of the titanium dioxide-containing powder, larger particles are preferable, and in that case, titanium dioxide-containing powder with an average particle diameter of 10 to 100 μm is preferably used. More preferably, it is 15 to 80 μm, and even more preferably, 20 to 60 μm. Furthermore, when titanium dioxide-containing powder is used in small device applications, a titanium dioxide-containing powder with a smaller particle size is required, and powders with an average particle size of 0.1 to 10 μm are preferably used. More preferably, powders with a particle size of 0.5 to 8 μm are preferred, and even more preferably, powders with a particle size of 1 to 6 μm are preferred. Furthermore, the titanium dioxide-containing powder of the present invention consists of aggregated particles (secondary particles) formed by the aggregation of primary particles, and the average particle diameter of the titanium dioxide-containing powder referred to here is the average particle diameter of the secondary particles. The average particle size of the titanium dioxide-containing powder can be measured by the method described in the examples below.

[0024] The titanium oxide-containing powder of the present invention preferably has a (D90-D10) / D50 of 4 or less in its laser diffraction particle size distribution. By using a material with such a narrow particle size distribution, the composition obtained by compounding it with a resin becomes more suitable for thin film formation, and the molded article formed using the composition has higher surface flatness. (D90-D10) / D50 is more preferably 3 or less, and even more preferably 2 or less. The (D90-D10) / D50 value of the titanium dioxide-containing powder can be calculated from the D90, D50, and D10 values ​​measured by the method described in the examples below.

[0025] The titanium dioxide-containing powder of the present invention preferably has a circularity of 0.7 or higher. Such a high circularity results in excellent packing and dispersibility when the titanium dioxide-containing powder is mixed with resin. The circularity is more preferably 0.75 or higher, and even more preferably 0.8 or higher. The circularity of the titanium dioxide-containing powder can be measured by the method described in the examples below.

[0026] The titanium oxide-containing powder of the present invention is suitable as a dielectric material because it has a high dielectric constant and a low dielectric loss tangent. When using the titanium oxide-containing powder of the present invention as a dielectric material, it may be mixed with a resin and used as a resin composition. A resin composition characterized by containing such titanium oxide-containing powder of the present invention and a resin is also one of the present inventions. When mixing titanium dioxide-containing powder into a resin material, a dispersant may be used in combination, to the extent that it does not impair the dielectric properties of the substrate material, or the titanium dioxide-containing powder may be surface-treated with a surface treatment agent selected from organic and / or inorganic surface treatment agents, in order to further improve the uniformity of the mixing into the resin material.

[0027] The above-mentioned dispersant is not particularly limited, and conventionally known dispersants can be used. Examples of dispersants include, but are not limited to, those consisting of various polymers of fatty acids, fatty acid metal salts, fatty acid esters, and fatty acid amides. Low molecular weight or high molecular weight dispersants can be used. The amount of dispersant added to the resin material can be set appropriately depending on the purpose.

[0028] Furthermore, the surface treatment agent for the titanium dioxide-containing powder is not particularly limited and can be appropriately selected and used depending on the intended application. Examples of organic surface treatment agents include organosilicon compounds such as silane coupling agents like hexadimethylsilazane and surfactants like organopolysiloxanes; organotitanium compounds such as titanium coupling agents; organophosphorus compounds such as phosphate esters; organofluorine compounds such as perfluorocarboxylic acids; fatty acids such as lauric acid, palmitic acid, and stearic acid; polyhydric alcohols such as trimethylolpropane, and alkanolamines such as triethanolamine. Examples of inorganic surface treatment agents include oxoacids (e.g., silicic acid and aluminic acid), metal salts of oxoacids (e.g., sodium silicate and sodium aluminate), oxides, hydroxides, and hydrated oxides of metals such as aluminum, silicon, zirconium, tin, titanium, antimony, zinc, cobalt, and manganese.

[0029] Titanium dioxide-containing powder that has been surface-treated with the above-mentioned surface treatment agent will have a layer of the surface treatment agent on the surface of the titanium dioxide-containing powder. Titanium dioxide-containing powder that has been surface-treated with a surface treatment agent may be surface-treated with either an organic surface treatment agent or an inorganic surface treatment agent, or it may be surface-treated with both. When it is surface-treated with both an organic and an inorganic surface treatment agent, it is preferable that it is surface-treated with the inorganic surface treatment agent first, and then with the organic surface treatment agent. In this case, the surface-treated titanium dioxide-containing powder will have a layer of inorganic surface treatment agent on the surface of the titanium dioxide-containing powder, and a layer of organic surface treatment agent on top of that.

[0030] 2. Method for producing titanium dioxide-containing powder The present invention provides a method for producing titanium dioxide-containing powder, comprising: a first step of preparing a slurry containing titanium dioxide and a solvent, wherein the average particle size of the secondary particles is 0.1 to 4 μm; a second step of obtaining granulated particles from the slurry obtained in the first step; and a third step of calcining the particles obtained in the second step at a temperature of 900 to 1250°C. In this way, by firing granulated particles of a predetermined size at a relatively low temperature, the resulting titanium oxide-containing powder has a high dielectric constant. Furthermore, firing causes the primary particles constituting the granulated particles to grow and form necks, reducing the specific surface area and thus the dielectric loss tangent. As a result, it is possible to produce titanium oxide-containing powder with a high dielectric constant, a low dielectric loss tangent, and particles suitable for mixing with resin.

[0031] The titanium dioxide used as a raw material for preparing the slurry in the first step described above preferably has an average primary particle size of 0.001 to 1 μm. By using titanium dioxide with a small average primary particle size, the titanium dioxide-containing powder obtained by the method for producing titanium dioxide-containing powder of the present invention can be made into a powder with small particle sizes, and the granulated particles can be made to have a well-organized internal and surface structure. The average primary particle size of the titanium dioxide is more preferably 0.001 to 0.5 μm, and even more preferably 0.001 to 0.2 μm. The average primary particle size of titanium dioxide can be measured by the method described in the examples below.

[0032] The titanium dioxide contained in the slurry prepared in the first step described above may have an average particle size of 0.1 to 4 μm for secondary particles. However, to make the titanium dioxide-containing powder obtained by the titanium dioxide-containing powder production method of the present invention closer to a spherical shape, it is preferable that the average particle size of the secondary particles be 0.1 to 3 μm. More preferably, it is 0.1 to 2 μm. The average particle size of titanium dioxide secondary particles can be measured by the method described in the examples below.

[0033] Examples of solvents used in the first step described above include water, methanol, ethanol, and propanol. Of these, water is preferred.

[0034] The concentration of the slurry prepared in the first step described above is not particularly limited, but the solid content concentration is preferably 0.5 to 30% by volume. With such a solid content concentration, it becomes easier to obtain granulated particles of an appropriate particle size in the second step, and the shape of the resulting titanium dioxide-containing powder can be made closer to a spherical shape. The solid content concentration of the slurry is more preferably 0.5 to 15% by volume, and even more preferably 1 to 8% by volume.

[0035] The first step described above may be any step of preparing a slurry containing titanium dioxide with an average particle size of secondary particles of 0.1 to 4 μm and a solvent, but it is preferable that the step be of preparing a slurry containing titanium dioxide with an average particle size of secondary particles of 0.1 to 4 μm, a strontium-containing compound and a solvent. By drying and calcining the slurry containing the strontium-containing compound in this way to produce titanium dioxide-containing powder, the resulting titanium dioxide-containing powder contains titanium dioxide and strontium titanate, thereby obtaining a powder with superior dielectric constant. Furthermore, by using a strontium-containing compound, the slurry becomes an aggregated system, and the occurrence of depressions in the particles obtained by granulation from the slurry is suppressed, so that the final titanium dioxide-containing powder tends to have a spherical particle shape. In addition, calcination can be performed at a lower temperature, thereby suppressing the aggregation of granulated particles during calcination. As a result, the resulting powder has excellent packing and dispersibility when mixed with resin.

[0036] When using a strontium-containing compound in the first step described above, the strontium-containing compound used is not particularly limited, and various compounds containing the element strontium can be used, but compounds that are partially or entirely water-soluble are preferred. Furthermore, when a partially water-soluble compound or a water-insoluble compound is mixed as solid particles in the slurry, it is preferable to use one with an average primary particle diameter of 1 μm or less. Examples of the strontium-containing compound include strontium carbonate, strontium acetate, strontium nitrate, strontium oxalate, strontium hydrogen carbonate, strontium titanate, etc., and one or more of these can be used. Among these, strontium-containing compounds such as strontium carbonate and strontium acetate are preferred. In particular, when using water-soluble strontium acetate, it is redeposited during spray drying to mix more uniformly, and the titanium oxide-containing powder obtained by the production method of the present invention is likely to become spherical particles with a more uniform internal structure and excellent dielectric properties.

[0037] When using a strontium-containing compound in the above first step, the amount of the strontium-containing compound used is preferably such that the amount of strontium element contained in the strontium-containing compound is 0.5 to 89 mol% with respect to 100 mol% of titanium element contained in titanium oxide used in the first step. By using such a ratio, the titanium oxide-containing powder obtained by the production method of the present invention becomes more excellent in dielectric properties. More preferably, the amount of strontium element contained in the strontium-containing compound is such that it is 4.6 to 64 mol% with respect to 100 mol% of titanium element contained in titanium oxide used in the first step, and even more preferably, the amount of strontium element is such that it is 9.9 to 40 mol%.

[0038] In the above first step, other components other than titanium oxide, a solvent, and a strontium-containing compound may be used. Examples of other components include dispersants and binders such as ammonium polyacrylate and polyvinyl alcohol, and one or more of these can be used. Particularly when the average primary particle diameter of titanium oxide is 0.1 μm or more and the specific surface area is 20 m 2 / g or less, it is preferable to use a binder. By using a binder, the strength of the granulated particles obtained in the second step can be increased, and relatively large titanium oxide particles that are difficult to granulate can also be granulated.

[0039] The amount of dispersant used in the first step described above is preferably 0 to 6% by mass relative to 100% by mass of titanium dioxide used in the first step. More preferably, it is 0 to 5% by mass, and even more preferably, it is 0 to 4% by mass.

[0040] The amount of binder used in the first step described above is preferably 0 to 4% by mass, relative to 100% by mass of titanium dioxide used in the first step. More preferably, it is 0 to 3% by mass, and even more preferably, 0 to 2% by mass.

[0041] In the first step described above, the method for preparing the slurry by mixing titanium dioxide with the solvent and other raw materials in the solvent is not particularly limited, and any method such as a ribbon mixer, Spartan mixer, planetary ball mill, or bead mill may be used. When using either a planetary ball mill or a bead mill, examples of media to be used include glass beads, alumina beads, zirconia beads, titania beads, silicon nitride beads, agate beads, and tungsten carbide beads.

[0042] The second step described above is a granulation step in which granulated particles are obtained from the slurry obtained in the first step. By preparing a slurry containing titanium oxide of an appropriate size in the first step and granulating using this slurry, granulated particles composed of primary particles of an appropriate size can be obtained, and aggregation between the granulated particles during calcination in the third step can be suppressed. Therefore, a powder with a particle size suitable for mixing with resin can be obtained without performing a particle crushing step. Furthermore, when these granulated particles composed of primary particles are calcined in the third step, the synthesis temperature of strontium titanate decreases when a strontium-containing compound is used in the first step, so strontium titanate can be sufficiently synthesized even with calcination at a low temperature in the third step.

[0043] In the second step described above, the method for obtaining granulated particles is not particularly limited, as long as granulated particles can be obtained from the slurry obtained in the first step. In addition to granulation by spray drying, wet granulation methods such as extrusion granulation, stirring granulation, fluid bed granulation, and rolling granulation, as well as dry granulation methods such as compacting and molding powder, can be used. Among these, the method of drying the slurry by spray drying to obtain granulated particles is preferred. By using spray drying, the composition of the composite powder containing titanium dioxide and other components can be easily changed by changing the raw materials of the slurry. When granulation is performed by spray drying, it is preferable to use a four-fluid nozzle type micro-mist spray dryer to obtain fine granulated particles of several microns.

[0044] The average particle size of the granulated particles obtained by granulating the slurry in the second step described above is not particularly limited and can be appropriately selected depending on the application of the titanium oxide-containing powder to be manufactured, but it is preferably 100 μm or less. The average particle size of the granulated particles obtained in the second step is usually 0.1 μm or more. By calcining granulated particles with such an average particle size in the third step, a titanium oxide mixed powder with a particle size suitable for mixing with resin can be obtained. Furthermore, given the importance of the high dielectric constant of the titanium oxide-containing powder produced, the average particle size of the granulated particles obtained in the second step is more preferably 15 to 80 μm, and even more preferably 20 to 60 μm. When the titanium dioxide-containing powder produced is used for small device applications, the average particle size of the granulated particles obtained in the second step is more preferably 0.1 to 30 μm, even more preferably 0.5 to 20 μm, and most preferably 1 to 10 μm. The average particle size of the granulated particles can be measured by the method described in the examples below.

[0045] The third step described above is a process of firing the granulated particles obtained in the second step at a temperature of 900 to 1250°C. When granulated particles composed of primary particles obtained in the second step are fired at such a temperature, the primary particles constituting the granulated particles grow and form necks, thereby reducing the specific surface area of ​​the granulated particles and lowering the dielectric loss tangent. In the granulated particles obtained in the second step, the primary particles within the granulated particles are closely adjacent to each other, making it easy for necks to form within the particles even when fired at a low temperature in the third step. However, neck formation is less likely between adjacent granulated particles, and the granulated particles do not easily aggregate. Therefore, a powder containing dispersed granulated particles can be obtained without performing a particle crushing process. While the particle crushing process deteriorates the dielectric properties of the particles, the manufacturing method of the present invention can obtain a powder with a small particle size without performing a particle crushing process. Therefore, a titanium oxide-containing powder with excellent dielectric properties while having a particle size suitable for mixing with resin can be obtained. Furthermore, firing the granulated particles obtained in the second step at such a relatively low temperature results in titanium oxide-containing powder particles that are not too hard. This prevents the mixing device's inner walls and stirring screws from being scraped or damaged when mixing titanium dioxide-containing powder with resin, thus suppressing wear on components caused by particles and the resulting contamination of foreign matter. The firing temperature for the particles can be 900 to 1250°C, but 1000 to 1250°C is preferable. More preferably, it is 1100 to 1200°C. Note that the firing temperature referred to here means the maximum temperature during firing. Furthermore, the firing time is preferably 0.5 to 8 hours, more preferably 1 to 7 hours, and even more preferably 2 to 6 hours. Note that the firing time referred to here means the holding time at the highest temperature during firing.

[0046] The heating rate during the third step described above is not particularly limited and can be set appropriately according to the size of the firing furnace and the amount of granulated particles to be fired, but for example, 50 to 300°C / h is preferred. More preferably, it is 50 to 200°C / h, and even more preferably, 50 to 100°C / h. The cooling rate is also preferably the same as the heating rate.

[0047] The present invention's method for producing titanium dioxide-containing powder may include other steps, as long as it includes the first to third steps described above. Other steps include removing beads after mixing when the raw materials are mixed using a bead mill in the first step, and classifying the materials by sieving. [Examples]

[0048] Specific examples are given below to illustrate the present invention in detail, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "wt%" mean "weight % (mass %)". The measurement methods for each physical property are as follows.

[0049] <Specific surface area> The specific surface area was measured using the BET single-point method with a Macsorb HM-1220 manufactured by Mountec. Pretreatment was performed at 130°C for 15 minutes under a pure nitrogen gas stream, and measurements were taken using a carrier gas mixture of 70% helium and 30% nitrogen. <Average primary particle diameter> The specific surface area was measured using the BET single-point method with a Macsorb HM-1220 manufactured by Mountec, and the average primary particle diameter was calculated. Pretreatment was performed at 200°C for 30 minutes under a pure nitrogen gas stream, and measurements were taken using a carrier gas mixture of 70% helium and 30% nitrogen. D=6 / (ρ·Sm) D: Average primary particle diameter [μm] ρ: True density [g / cm 3 ] Sm: Specific surface area [m 2 / g] <Average particle size of secondary particles> The average particle size of secondary particles was measured using the Microtrac-Bell MT3300II. The powder to be measured was placed in a bath filled with a 0.0025 mass% sodium hexametaphosphate aqueous solution, and a dispersed slurry was obtained by ultrasonic dispersion at an output of 40W for 120 seconds within the same device. The particle refractive index was measured at 2.72, the solvent refractive index at 1.333, and the measurement was performed on a volume basis. The median diameter (D50) obtained here was taken as the average particle diameter of the secondary particles. <Particle size distribution of granulated particles> The particle size distribution was measured using the Microtrac-Bell MT3300II. The powder to be measured was placed in a bath filled with a 0.0025 mass% sodium hexametaphosphate aqueous solution, and a dispersed slurry was obtained by ultrasonic dispersion at an output of 40W for 120 seconds within the same device. The particle refractive index was measured at 2.72, the solvent refractive index at 1.333, and the measurement was performed on a volume basis. From the particle size distribution measurement results obtained here, the cumulative frequencies D10, D50, and D90 were determined. <Relative permittivity ε·Dielectric loss tangent tanδ> The relative permittivity ε and dielectric loss tangent tanδ were measured using a measuring device consisting of a powder cavity resonator (manufactured by AET Corporation) connected to a vector network analyzer P9373B (manufactured by Keysight Corporation). The measurement powder was packed into a quartz tube to achieve a bulk density of approximately 1.0, and measurements were performed under conditions of a frequency of 10 GHz. <SEM、SEM-EDS> SEM observation and SEM-EDS measurements were performed using a JEOL JSM-6510A. The measurement samples were pre-coated with platinum using a JEOL JEC-3000FC auto fine coater. <xrd> X-ray diffraction was measured using a Rigaku MiniFlex 600-C. The measurement conditions were 1D scan, 10-90°, step size of 0.01°, measurement speed of 20.0° / min, no spin, tube voltage of 40kV, and tube current of 15mA. The powder was ground in an agate mortar before measurement. <Titaniumic acid content> The Ti and Sr content was measured using a Rigaku ZSX PrimusII X-ray fluorescence spectrometer. The measurement application was EZ scan, and the measurement conditions were vacuum atmosphere, measurement diameter 30 mm, and standard measurement time. The measurement powder sample was formed into a Φ35 mm pellet. The strontium titanate content was calculated from the obtained measurement values. <Circularity> The circularity was determined by using SEM images measured by the method described above, analyzing over 100 particles with DeepCle, an AI image analysis software manufactured by Sakai Chemical Industry Co., Ltd., and taking the average value of the circularity. The image analysis model used was AI model:4.3201_2f_r. As examples of analysis, the analysis results for the titanium dioxide mixed powder of Example 12 and the titanium dioxide mixed powder of Comparative Example 1 are shown in Tables 1 and 2, respectively.

[0050] [Table 1]

[0051] [Table 2]

[0052] Example 1 400 g of titanium dioxide (Sakai Chemical Industry Co., Ltd., STR-100N, average primary particle size 0.015 μm) was added to 3905 g of pure water. This was thoroughly stirred with a stirrer, and the resulting slurry was passed through a sieve (Tokyo Screen Co., Ltd., test sieve, mesh size 150 μm) to remove coarse particles, obtaining a 2.4 vol% slurry. The average particle size of the titanium dioxide aggregated particles in the obtained slurry was 2.0 μm. The obtained slurry was granulated using a spray dryer (Okawara Chemical Machinery Co., Ltd., spray bag dryer, BDP-22E, M-type pin disk, disk rotation speed 20,000 rpm) to obtain titanium dioxide granulated powder. The obtained granules were calcined in an electric furnace under the conditions of heating at a rate of 100°C / h and holding at 900°C for 2 hours to obtain the desired titanium dioxide-containing powder (titanium dioxide granulated powder). The obtained titanium oxide-containing powder had an average particle size of 23.1 μm, a dielectric constant of 17.1 at 10 GHz, and a dielectric loss tangent of 0.0021. Its specific surface area was 6.3 m². 2 It was / g.

[0053] Example 2 Titanium dioxide-containing powder was obtained in the same manner as in Example 1, except that the amount of titanium dioxide used was changed as shown in Table 3. Table 3 shows the dielectric constant, dielectric loss tangent, and specific surface area of ​​the obtained titanium oxide-containing powder at 10 GHz.

[0054] Example 3 800g of titanium dioxide (Sakai Chemical Industry Co., Ltd., STR-100N, average primary particle size 0.015μm) was added to 3810g of pure water. This was crushed and mixed using a bead mill, and the resulting slurry was passed through a sieve (Tokyo Screen Co., Ltd., test sieve, mesh size 25μm) to remove the beads, obtaining a slurry with a solid content of 4.8 vol%. The average particle size of the titanium dioxide aggregated particles in the obtained slurry was 0.7μm. The obtained slurry was granulated using a spray dryer (Okawara Chemical Machinery Co., Ltd., spray bag dryer, BDP-22E, M-type pin disk, disk rotation speed 20,000 rpm) to obtain titanium dioxide granulated powder. The obtained granules were calcined in an electric furnace under the conditions of heating at a rate of 100°C / h and holding at 900°C for 2 hours to obtain the desired titanium dioxide-containing powder (titanium dioxide granulated powder). The obtained titanium oxide-containing powder had an average particle size of 21.0 μm, a dielectric constant of 16.8 at 10 GHz, and a dielectric loss tangent of 0.0015. Its specific surface area was 7.2 m². 2 It was / g.

[0055] Examples 4 and 5 Titanium oxide-containing powder was obtained in the same manner as in Example 3, except that the firing temperature and holding time were changed as shown in Table 3, while the heating rate was 100°C / h. Table 3 shows the dielectric constant, dielectric loss tangent, and specific surface area of ​​the obtained titanium oxide-containing powder at 10 GHz.

[0056] Example 6 761.6g of pure water was mixed with 3.1g of ammonium polyacrylate (Kao Corporation, Poise 532A), and then 116g of titanium dioxide (Sakai Chemical Industry Co., Ltd., STR-100N, average primary particle size 0.015μm) and 39.8g of strontium carbonate (Sakai Chemical Industry Co., Ltd., SW-K, average primary particle size 0.22μm) were added. This mixture was crushed and mixed using a bead mill, and the resulting slurry was passed through a sieve (Tokyo Screen Co., Ltd., test sieve, mesh size 25μm) to remove the beads, obtaining a slurry with a solid content of 4.8 vol%. The average particle size of the titanium dioxide secondary particles in the obtained slurry was 1.1 μm. The obtained slurry was granulated using a spray dryer (GF Corporation, Micro Mist Spray Dryer MDL-050CM) to obtain a mixed granulated powder of titanium dioxide and strontium carbonate. The resulting mixed granulated powder was calcined in an electric furnace under the conditions of heating at a rate of 100°C / h and holding at 1000°C for 4 hours to obtain the desired titanium oxide-containing powder (composite granulated powder of titanium dioxide and strontium titanate). The obtained titanium oxide-containing powder had an average particle size of 5.2 μm, a dielectric constant of 16.2 at 10 GHz, and a dielectric loss tangent of 0.0025. Its specific surface area was 10.1 m². 2 It was / g. Figure 3 shows the particle size distribution measurement results of the obtained titanium dioxide-containing powder, and Figure 4 shows the SEM observation results. Figure 5-1 shows the SEM-EDS measurement results, and Figure 5-2 shows the analytical spectrum. Furthermore, Figure 6 shows the XRD measurement results of the obtained titanium dioxide-containing powder. Figures 5-1 and 5-2 confirmed that the titanium dioxide-containing powder obtained was a composite granulated powder of titanium dioxide and strontium titanate. Furthermore, Figure 6 confirmed that the titanium dioxide-containing powder was composed of crystals of titanium dioxide and strontium titanate.

[0057] Examples 7-10 Titanium dioxide-containing powder was obtained in the same manner as in Example 1, except that the amounts of titanium dioxide and strontium carbonate used, and the firing temperature were changed as shown in Table 3. Table 3 shows the dielectric constant, dielectric loss tangent, and specific surface area of ​​the obtained titanium oxide-containing powder at 10 GHz.

[0058] Example 11 695 g of pure water was mixed with 98.7 g of strontium hydroxide octahydrate (manufactured by Fujifilm Wako Pure Chemical Industries), and then 44.6 g of acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries) was added to completely dissolve it, obtaining an aqueous solution of strontium acetate. The weight of strontium acetate obtained when the entire amount of acetic acid and strontium hydroxide reacted to form strontium acetate was defined as the amount of strontium acetate used in this example. 160 g of titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., STR-100N, average primary particle size 0.015 μm) and ammonium polyacrylate (manufactured by Kao Corporation, Poise 532A) were added to this solution, and the mixture was crushed and mixed using a bead mill. The resulting slurry was passed through a sieve (manufactured by Tokyo Screen Co., Ltd., test sieve, mesh size 25 μm) to remove the beads, obtaining a slurry with a solid content concentration of 4.8 vol%. The average particle size of the titanium dioxide secondary particles in the obtained slurry was 1.0 μm. The obtained slurry was granulated using a spray dryer (GF Corporation, Micro Mist Spray Dryer MDL-050CM) to obtain a mixed granulated powder of titanium dioxide and strontium acetate. The resulting mixed granulated powder was calcined in an electric furnace under the conditions of heating at a rate of 100°C / h and holding at 1100°C for 4 hours to obtain the desired titanium oxide-containing powder (composite granulated powder of titanium dioxide and strontium titanate). The obtained titanium oxide-containing powder had an average particle size of 6.6 μm, a dielectric constant of 15.1 at 10 GHz, and a dielectric loss tangent of 0.0016. Its specific surface area was 4.4 m². 2 It was / g. Figure 7 shows the particle size distribution measurement results of the obtained titanium dioxide-containing powder, and Figure 8 shows a photograph of the SEM observation results. Figure 9-1 shows a photograph of the SEM-EDS measurement results, and Figure 9-2 shows the analytical spectrum. Furthermore, Figure 10 shows the XRD measurement results of the obtained titanium dioxide-containing powder. Figure 9-1 confirmed that the titanium dioxide-containing powder obtained from 9-1 is a composite granulated powder of titanium dioxide and strontium titanate. Furthermore, Figure 10 confirmed that the titanium dioxide-containing powder obtained from 10 is composed of crystals of titanium dioxide and strontium titanate.

[0059] Example 12 670 g of pure water was mixed with 98.7 g of strontium hydroxide octahydrate (manufactured by Fujifilm Wako Pure Chemical Industries), and then 31.2 g of acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries) was added to partially dissolve it, obtaining an aqueous solution of strontium acetate containing undissolved crystals of strontium hydroxide octahydrate. The weight of strontium acetate obtained when all of the added acetic acid reacted with some of the strontium hydroxide to form strontium acetate was defined as the amount of strontium acetate used in this example. 160 g of titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., STR-100N, average primary particle size 0.015 μm) and ammonium polyacrylate (manufactured by Kao Corporation, Poise 532A) were added to this solution, and the mixture was crushed and mixed using a bead mill. The resulting slurry was passed through a sieve (manufactured by Tokyo Screen Co., Ltd., test sieve, mesh size 25 μm) to remove the beads, obtaining a slurry with a solid content concentration of 7.4 vol%. The average particle size of the titanium dioxide secondary particles in the obtained slurry was 0.8 μm. The obtained slurry was granulated using a spray dryer (GF Corporation, Micro Mist Spray Dryer MDL-050CM) to obtain a mixed granulated powder of titanium dioxide and strontium acetate. The resulting mixed granulated powder was calcined in an electric furnace under the conditions of heating at a rate of 100°C / h and holding at 1150°C for 4 hours to obtain the desired titanium oxide-containing powder (composite granulated powder of titanium dioxide and strontium titanate). The obtained titanium oxide-containing powder had an average particle size of 5.4 μm, a dielectric constant of 15.6 at 10 GHz, and a dielectric loss tangent of 0.0023. Its specific surface area was 2.8 m². 2 It was / g.

[0060] Example 13 Titanium oxide-containing powder was obtained in the same manner as in Example 9, except that the firing temperature was changed as shown in Table 3. The obtained titanium dioxide-containing powder was sintered and aggregated, so the particle size was adjusted by grinding in a mortar. The obtained titanium oxide-containing powder had a dielectric constant of 15.7, a dielectric loss tangent of 0.0033, and a specific surface area of ​​2.0 m² at 10 GHz. 2 It was / g.

[0061] Comparative Example 1 One g of anatase-type titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "SSP-25", average primary particle size 0.006 μm) was calcined at 1000°C for four hours. The obtained titanium oxide powder had an average particle size of 3.2 μm, a dielectric constant of 10.7 at 10 GHz, and a dielectric loss tangent of 0.0033. The specific surface area was 3.0 m². 2 It was / g.

[0062] Comparative Example 2 Strontium hydroxide (manufactured by Sakai Chemical Industry Co., Ltd., product name "ST-03", average primary particle size 0.23 μm) had an average particle diameter of 0.6 μm, a dielectric constant of 13.8 at 10 GHz, and a dielectric loss tangent of 0.0187. Its specific surface area was 5.4 m². 2 It was / g.

[0063] Comparative Example 3 Titanium oxide-containing powder was obtained in the same manner as in Example 9, except that the firing temperature was changed as shown in Table 3. The average particle size of the titanium dioxide secondary particles in the obtained slurry was 0.9 μm. The obtained slurry was granulated using a spray dryer (GF Corporation, Micro Mist Spray Dryer MDL-050CM) to obtain a mixed granulated powder of titanium dioxide and strontium carbonate. The resulting mixed granulated powder was calcined in an electric furnace under the conditions of heating at a rate of 100°C / h and holding at 1300°C for 4 hours to obtain the desired titanium oxide-containing powder (composite granulated powder of titanium dioxide and strontium titanate). The obtained titanium dioxide-containing powder was sintered and aggregated, so the particle size was adjusted by grinding in a mortar. The obtained titanium oxide-containing powder had an average particle size of 6.7 μm, a dielectric constant of 13.2 at 10 GHz, and a dielectric loss tangent of 0.0021. Its specific surface area was 1.4 m². 2 It was / g.

[0064] Comparative Example 4 Titanium oxide-containing powder was obtained in the same manner as in Example 11, except that the firing temperature was changed as shown in Table 3. The obtained titanium dioxide-containing powder had an average particle size of 4.7 μm, a dielectric constant of 16.6 at 10 GHz, a dielectric loss tangent of 0.0037, and a specific surface area of ​​21.3 m². 2 It was / g.

[0065] [Table 3]

[0066] The results in Table 3 confirm that by producing titanium oxide-containing powder using the present invention, it is possible to obtain titanium oxide-containing powder that has a high dielectric constant and a low dielectric loss tangent, exhibiting excellent dielectric properties, and having a specific surface area suitable for mixing with resin materials.< / xrd>

Claims

1. A powder containing titanium dioxide, The powder has a dielectric constant of 14 or higher at 10 GHz, a dielectric loss tangent of 0.0035 or lower, and a specific surface area of ​​1.5 to 20 m². ２ A titanium dioxide-containing powder characterized by having a concentration of / g.

2. The titanium dioxide-containing powder according to claim 1, further characterized by containing strontium titanate.

3. The titanium dioxide-containing powder according to claim 1, characterized in that the average particle size is 0.1 to 100 μm.

4. A resin composition characterized by comprising a titanium dioxide-containing powder and a resin according to any one of claims 1 to 3.

5. A method for producing titanium dioxide-containing powder, The manufacturing method comprises a first step of preparing a slurry containing titanium dioxide and a solvent, wherein the average particle size of the secondary particles is 0.1 to 4 μm, and The second step involves obtaining granulated particles from the slurry obtained in the first step, The process includes a third step in which the particles obtained in the second step are calcined at a temperature of 900 to 1250°C. A method for producing titanium dioxide-containing powder, characterized by the following:

6. The method for producing titanium dioxide-containing powder according to claim 5, characterized in that the first step is a step of preparing a slurry containing titanium dioxide having an average particle size of secondary particles of 0.1 to 4 μm, a strontium-containing compound, and a solvent.

7. The method for producing titanium dioxide-containing powder according to claim 6, characterized in that the strontium-containing compound is at least one selected from the group consisting of strontium carbonate, strontium acetate, strontium nitrate, strontium oxalate, strontium bicarbonate, and strontium titanate.

8. The method for producing titanium oxide-containing powder according to claim 5, characterized in that the second step is performed by spray-drying the slurry.

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