Modified metal oxide particulate material and method for producing same

Abstract

The present invention addresses the problem of providing a modified metal oxide particulate material having high dispersibility even when the amount of a modifying material is small. The dispersibility can be improved by interposing a modifying material between particles of a surface-treated metal oxide particulate material. In particular, by suppressing the reaction between pieces of the modifying material, a satisfactory effect was exhibited even when the amount of the modifying material was reduced. Specifically, this modified metal oxide particulate material comprises: a surface-treated metal oxide particulate material having, on the surface thereof, a functional group other than a phenyl group; and a modifying material that comprises a silicon-containing compound having a phenyl group and that adheres to the surface of the surface-treated metal oxide particulate material. After the modified metal oxide particulate material is washed with methyl ethyl ketone, the C / H value calculated from the surface area H (m2) and the carbon content C (mass%) per gram is reduced by at least 0.03 but less than 0.1, the particle gauge is 20 μm or less, and the C / H value after the washing is not more than 0.07.

Description

Modified metal oxide particle material and method for producing the same

[0001] The present invention relates to a modified metal oxide particle material that can be used by dispersing it in a resin material or an organic solvent, and to a method for producing the same.

[0002] Conventionally, resin compositions in which a filler material made of a metal oxide is dispersed in a resin material have been widely used. Dispersing a filler material made of a metal oxide improves the mechanical properties of the resin composition and its cured product (Patent Document 1, etc.). In such resin compositions, it is desirable that the filler material is uniformly dispersed. To obtain such a resin composition, the filler material can be directly dispersed in the resin material, or a slurry composition in which the filler material is dispersed in an organic solvent can be manufactured and then mixed into the resin material to form the resin composition.

[0003] To solve the above problems, the applicant has developed a technology to improve dispersibility by attaching a modifying material to the surface of a surface-treated metal oxide particle material (Patent Documents 2 and 3).

[0004] Japanese Patent No. 6603777, International Publication No. 2021 / 210628, International Publication No. 2024 / 236674

[0005] According to the technologies disclosed in Patent Documents 2 and 3, high dispersibility in resin materials is achieved. However, it has been found that in the technologies disclosed in Patent Documents 2 and 3, aggregate formation progresses over time, and dispersibility decreases over time.

[0006] This invention was completed in view of the above circumstances, and aims to solve the problem of providing a modified metal oxide particle material, which is a surface-treated metal oxide particle material that can exhibit higher dispersibility over a longer period than the prior art, and a method for producing the same.

[0007] To solve the above problems, the inventors conducted diligent research. As a result, they discovered that the technology disclosed in Patent Documents 2 and 3 makes it possible to maintain high dispersibility over a long period of time by forming granules, and thus completed the present invention. The difference between the aggregates formed over time in the prior art and the granules formed in the present invention is that the granules can be easily redispersed to the primary particles that form the granules, compared to the aggregates.

[0008] (1) That is, the modified metal oxide particle material of the present invention that solves the above problems is a granule comprising a surface-treated metal oxide particle material having functional groups other than phenyl groups on its surface, and a modifying material consisting of a silicon-containing compound having phenyl groups, which adheres to the surface of the surface-treated metal oxide particle material, wherein the particle size of the primary particles is 0.01 μm or more and 5 μm or less, the D10 of the granule measured by dry method is 3 μm or more and 50 μm or less, the D90 is 50 μm or more and 1000 μm or less, and the surface area H (m²) per gram ２ The C / H value calculated from the carbon content C (mass%) decreases by 0.001 or more after washing with methyl ethyl ketone, the particle size is 20 μm or less on a particle gauge, and the C / H value after washing is 0.07 or less. The modified metal oxide particle material of the present invention may have one or more of the components described in (2) to (8) below. (2) The particle size after being left in a sealed container at 45°C for 50 hours is 20 μm or less on a particle gauge. (3) It is preferable that the (dielectric loss tangent) / H is 0.0005 or less. (4) The modified metal oxide particle material can be prepared by attaching a modified material solution obtained by dissolving or dispersing the modified material in A mL of solvent to the surface-treated metal oxide particle material, and then heating and drying it at T°C for m minutes (however, T × m ÷ A is 150 or less). (5) The silicon-containing compound constituting the modified material is a silane compound having a phenyl group, or a condensate of a silane compound having a phenyl group and a silane compound having a hydrocarbon group directly bonded to Si. (6) The silane compound having a phenyl group is ((C ６ H ５ ) X) ｎ -Si-OR （４－ｎ） Represented as, the silane compound having the hydrocarbon group is Rｎ -Si-OR （４－ｎ） represented by: wherein X is a direct bond, -(CH ２ ) ｑ -, or -O-; q is an integer of 0 to 3; n is an integer of 1 to 3 independently selected for each molecule; R is a hydrocarbon group having 1 to 3 carbon atoms independently selected for each functional group) (7) The silicon-containing compound constituting the modified material is represented by general formula (1): R1-O-(SiZ1Z2O) ｎ -(SiZ3Z4O) ｍ -R2, wherein in the formula, Z1 is (C ６ H ５ )X-; Z2 to Z4 are each independently (C ６ H ５ )X-, a hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or -O that bonds to other groups among Z2 to Z4 ｒ -(CH ２ ) ｐ -O ｔ -; X is a direct bond, or -(CH ２ ) ｑ(8) The surface-treated metal oxide particle material is surface-treated with a silane compound. (9) The present invention provides a method for producing a modified metal oxide particle material that solves the above problems, comprising: a surface treatment step of surface-treating a metal oxide particle material with a silane compound to produce a surface-treated metal oxide particle material; a dispersion step of dispersing a silicon-containing compound having a phenyl group in a dispersion slurry obtained by dispersing the surface-treated metal oxide particle material in A mL of a dispersion medium; a drying step of drying the dispersion medium by heating it at T°C for m minutes after the dispersion step to deposit the modified material consisting of the silicon-containing compound onto the surface of the surface-treated metal oxide particle material to produce a modified metal oxide particle material; and a granulation step performed simultaneously with or after the dispersion step of granulating the modified metal oxide particle material. Here, T × m ÷ A is 150 or less.

[0009] The modified metal oxide particle material of the present invention can be improved in dispersibility in resin materials and organic solvents by pre-interposing a modifying material between surface-treated metal oxide particle materials. Furthermore, by pre-binding the particles together with the modifying material to form a granule, it is possible to maintain high dispersibility over a long period of time. The modifying material interposed between the surface-treated metal oxide particle materials constituting the granule not only protects the surface of the surface-treated metal oxide particle materials, but the modifying material itself also easily disintegrates, allowing the surface-treated metal oxide particle materials to disperse down to primary particles.

[0010] The modified metal oxide particle material and its manufacturing method of the present invention will be described in detail below based on embodiments. The modified metal oxide particle material of this embodiment is a material that can be suitably used as a filler material dispersed in resin materials and organic solvents. It is particularly preferable that it be provided in a dry state. When the modified metal oxide particle material is dispersed in the resin material and organic solvent during use, the modifying material adhering to the surface of the modified metal oxide particle material migrates into the organic solvent and exerts its effect.

[0011] Furthermore, the numerical values ​​described herein can be used to define the range in which those values ​​are used as upper or lower limits when making corrections, and that range may or may not include those values. In addition, the numerical range "x to y" described herein includes the lower limit x and the upper limit y within that range.

[0012] Furthermore, these upper and lower limits, along with the numerical values ​​listed in the specification or examples, can be arbitrarily combined to form a new numerical range. The new numerical range may also be a range that does not include one or both of the upper and lower limits. For example, a range greater than x can be adopted, or a range less than y can be adopted. In addition, numerical values ​​arbitrarily selected from any of the above numerical ranges can be used as the upper and lower limits of the new numerical range.

[0013] (Modified Metal Oxide Particle Material) The modified metal oxide particle material of this embodiment is a granule formed by the aggregation of surface-treated metal oxide particle material as primary particles, and contains a modifying material. The modifying material is present on the surface of the surface-treated metal oxide particle material and interposes between the surface-treated metal oxide particle material when forming the granule.

[0014] The particle size of the granulated material is D10 between 3 μm and 50 μm. Examples of lower limits for D10 include 4 μm, 5 μm, 6 μm, 7 μm, and 8 μm, while examples of upper limits include 45 μm, 40 μm, 35 μm, 30 μm, and 25 μm. The particle size of the granulated material is D90 between 50 μm and 1000 μm. Examples of lower limits for D90 include 55 μm, 60 μm, 65 μm, 70 μm, and 75 μm, while examples of upper limits include 900 μm, 850 μm, 800 μm, 750 μm, and 700 μm. D10 and D90 are calculated from the particle size distribution measured dry using a laser diffraction particle size distribution analyzer. Specifically, D10 and D90 represent the particle sizes of the particles located at the 10% and 90% positions, respectively, based on volume, from smallest to largest particle size.

[0015] Surface-treated metal oxide particle materials are metal oxide particle materials that have undergone surface treatment. Examples of metal oxide particle materials include silica, alumina, zirconia, titania, and composite oxides thereof. Examples of composite oxides include calcium titanate, barium titanate, and zeolites. The particle size of the surface-treated metal oxide particle material is not particularly limited, but it is desirable to have a particle size distribution suitable for use as a filler material. For example, it can be between 0.01 μm and 5 μm. Lower limits can be set to 0.01 μm, 0.03 μm, 0.05 μm, 0.1 μm, 0.3 μm, 0.5 μm, etc., and upper limits can be set to 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc. These upper and lower limits can be combined arbitrarily.

[0016] Surface-treated metal oxide particle materials have functional groups other than phenyl groups on their surface. Examples of functional groups other than phenyl groups include carbon-containing functional groups such as alkyl groups, vinyl groups, epoxy groups, methacrylic groups, amino groups, and isocyanate groups. There are no particular limitations on the method of introducing these functional groups, but they can be introduced by surface-treating the metal oxide particle material with a silane compound having these functional groups. For example, the silane compound can be brought into direct contact with the surface of the metal oxide particle material, or a solution can be prepared using some solvent and brought into contact with the surface. After that, the material can be left to stand or heated until the reaction is complete.

[0017] When introducing functional groups using silane compounds, it is expected that they will react and bond with OH groups present on the surface of the metal oxide particle material. Preferably, 50% or more of the OH groups are lost through the reaction, more preferably 70% or more, even more preferably 90% or more, and particularly preferably 100%. In addition, if functional groups other than phenyl groups are introduced, some phenyl groups may also be introduced.

[0018] The modifying material is a material adhering to the surface of the surface-treated metal oxide particle material. Adhesion primarily refers to physical adsorption, meaning that only a small amount is chemically reacted. Whether or not physical adsorption is the primary mechanism is determined by whether 30% or more (preferably 50% or more, and even more preferably 70% or more) of the modifying material is desorbed by mass when dispersed in an organic solvent.

[0019] The modified material may partially react with the surface of the surface-treated metal oxide particle material. For example, the surface area H(m²) per gram of the surface-treated metal oxide particle material. ２ The C / H value calculated from the carbon content C (mass%) after washing can be reacted up to a range of 0.07 or less, and can also be reacted up to a range of 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, and 0.02 or less. The washing conditions are as follows: 5 g of modified metal oxide particle material is placed in 35 mL of methyl ethyl ketone (MEK) and washed by applying ultrasound for 5 minutes. The type and amount of modified material is as follows: Surface area H (m²) per gram of surface-treated metal oxide particle material. ２ The C / H value calculated from the carbon content C (mass%) changes by 0.001 or more before and after washing with MEK, with lower limits of 0.0015, 0.0020, 0.0025, 0.0035, 0.0040, and 0.0045. Here, the carbon content C also includes carbon derived from compounds having functional groups other than phenyl groups that are bonded to the surface of the surface-treated metal oxide particle material.

[0020] In the case of silane compounds containing one silicon atom, silane compounds having two phenyl groups are preferred. For example, diphenyldialkoxysilane. The alkoxy group is preferably a methoxy group or an ethoxy group, with a methoxy group being particularly preferred. Additives (modifiers) having two phenyl groups have greater steric hindrance compared to additives having one phenyl group, thereby improving dispersibility, and their reduced reactivity prevents the additive from strongly bonding to the surface of the surface-treated metal oxide particle material.

[0021] The modifying material can be a silane compound having a phenyl group or a condensate of a silane compound having a phenyl group and a silane compound having a hydrocarbon group directly bonded to Si. The condensate can be produced, for example, by mixing and reacting a silane compound containing one silicon element. It is preferable to carry out the reaction with the addition of a catalyst. Examples of catalysts include precious metal catalysts such as platinum and alkalis.

[0022] For example, a silane compound having a phenyl group is ((C ６ H ５ ) X) ｎ -Si-OR （４－ｎ） Examples include silane compounds having a hydrocarbon group, R ｎ -Si-OR （４－ｎ） Examples include: (X is directly bonded, or -(CH ２ ) ｑ (either - or -O-; q is an integer from 0 to 3; n is an integer from 1 to 3 independently selected for each molecule; R is a hydrocarbon group having 1 to 3 carbon atoms independently selected for each functional group). X is preferably directly bonded. For example, diphenyldialkoxysilane is a compound in which X is directly bonded and n is 2.

[0023] Furthermore, the silicon-containing compound that constitutes the modified material has the general formula (1): R1-O-(SiZ1Z2O) ｎ -(SiZ3Z4O) ｍ -R2 can be adopted. In the formula, Z1 is (C ６ H ５ )X-;Z2-Z4 are each independent (C ６ H ５), X-, a hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and -O that bonds between other Z2 to Z4 ｒ -(CH ２ ) ｐ -O ｔ -; X is a direct bond, -(CH ２ ) ｑ -, or -O-; n and p are integers of 1 or more; m is an integer of 0 or more; q is an independently selected integer of 0 or more for each occurrence; r and t are each independently selected from 0 or 1; R1 and R2 are each independently selected hydrocarbon group having 1 to 3 carbon atoms or alkoxy group having 1 to 3 carbon atoms.

[0024] The modified metal oxide particle material of the present embodiment preferably has a value of (dielectric loss tangent) / specific surface area of 0.0005 or less, more preferably 0.0004 or less, and still more preferably 0.003 or less. The method for measuring dielectric loss tangent complies with JIS C 2138 (2007). Specifically, the relative permittivity and dielectric loss tangent at 1 GHz were measured using a network analyzer (product name: "E5071C", manufactured by Keysight) and the cavity resonator perturbation method. This measurement was performed in accordance with ASTM D2520 (JIS C 2565 (1992)).

[0025] The modified metal oxide particle material of the present embodiment has a value measured with a grind gauge of 20 µm or less. The grind gauge measurement is evaluated with a grind gauge after stirring 10 g of epoxy resin (manufactured by Nippon Steel Chemical & Materials, model number ZX-1059), 20 g of MEK, and 10 g of the modified metal oxide particle material with a rotation-revolution mixer. Evaluation by grind gauge is performed in accordance with JIS K 5600-2-5. The measured value of the grind gauge is a value that correlates with the particle size of aggregates. That is, particles broken during measurement by the grind gauge correspond to the granulated product of the present embodiment, not particles formed by aggregation.

[0026] (Method for producing modified metal oxide particle material) The method for producing modified metal oxide particle material of the present embodiment includes a surface treatment step, a dispersion step, a drying step, and a granulation step.

[0027] The surface treatment process involves surface-treating the metal oxide particle material with a silane compound to produce surface-treated metal oxide particle material. While there are no particular limitations on the method of producing the metal oxide particle material, examples include the VMC method (Vaporized Metal Combustion Method) and the melting method. Metal oxide particle material produced by the VMC method is dense, has low water absorption, and exhibits excellent electrical properties. The VMC method is a method of producing metal oxide particle material by immersing particles made of the metal constituting the material in a flame in an oxidizing atmosphere and burning them.

[0028] The surface treatment process involves introducing functional groups other than phenyl groups to the surface. If the material has functional groups other than phenyl groups, phenyl groups can also be added and introduced. The preferred method for introducing functional groups is to perform surface treatment with a silane compound containing the functional group to be introduced. Surface treatment can be carried out by bringing a surface treatment agent containing the functional group to be introduced into contact with the surface of the metal oxide particle material. Contact can be made by directly applying the surface treatment agent in liquid or gaseous form, or by applying it as a solution dissolved in some solvent. The amount of surface treatment agent is not particularly limited, but an amount sufficient to ensure that the amount of OH groups present on the surface of the metal oxide particle material is equal to the aforementioned retention rate can be used.

[0029] The dispersion process involves dispersing the surface-treated metal oxide particle material in a dispersion medium to form a dispersion slurry, and then dispersing a silicon-containing compound in the dispersion slurry. The silicon-containing compound and its amount can be those described above for the modified metal oxide particle material of this embodiment.

[0030] Examples of dispersion media for the dispersion slurry include MEK, isopropyl alcohol, propylene glycol monomethyl ether acetate, cyclohexanone, methyl isobutyl ketone, toluene, N-methylpyrrolidone, N-ethylpyrrolidone, and gamma-butyrolactone. While there are no particular limitations on the content of surface-treated metal oxide particle material in the dispersion slurry, it can range from approximately 10% to 80% based on the total mass. Lower limits can be 10%, 30%, or 50%, and upper limits can be 60%, 70%, or 80%. These upper and lower limits can be combined arbitrarily.

[0031] During the preparation of dispersed slurries and the dispersion of modifying materials into them, stirring, shearing, or ultrasonic irradiation can be applied.

[0032] The drying process is a process for removing the dispersion medium. The method for removing the dispersion medium is not particularly limited, but when the drying time until the dispersion medium is gone is m minutes, the temperature at that time is T°C, and the volume of the dispersion medium is A mL, then T × m ÷ A should be 150 or less, with upper limits of 140, 130, 120, 110, 100, 90, and 80.

[0033] By keeping these upper limits below the target, the progress of the reaction between the modified materials is suppressed. If the reaction progress is equivalent to that when it is below these upper limits, then a modified metal oxide particle material produced by another method can be said to be a modified metal oxide particle material of this embodiment, even though it cannot be said to have been produced by the method for producing modified metal oxide particle materials of this embodiment.

[0034] Temperature T is the average temperature of the dispersion slurry during the drying time. Here, the start of the drying time is when the temperature T of the dispersion slurry reaches or exceeds the start temperature after the dispersion slurry is prepared in the dispersion step, and the end of the drying time, which is determined to be when the dispersion medium is depleted, is when the amount of dispersion medium becomes 1% by mass or less. Even if the temperature of the dispersion slurry reaches or exceeds the start temperature, if it subsequently falls below the start temperature, it is excluded from the drying time until it rises or exceeds the start temperature again. Here, the start temperature is 110°C, but 105°C, 100°C, 80°C, 60°C, and 40°C can also be used.

[0035] While there are no specific limitations on the heating method, examples include simple heating and heating while simultaneously reducing pressure. In particular, spray drying using a disc rotor or pressure nozzle can be employed during heating, which is preferable because it can effectively shorten the drying time (in minutes).

[0036] Upon drying, the silicon-containing compound is converted into a modifying material. The modifying material can be either a material that dissolves in the dispersion medium or a material that does not dissolve. If it dissolves, it precipitates and forms particles as the dispersion medium dries. If the silicon-containing compound does not dissolve in the dispersion medium, it adheres directly to the surface of the surface-treated metal oxide particle material.

[0037] The granulation process is performed simultaneously with or after the dispersion process. In other words, by granulating after the dispersion process, in which the modifying material adheres to the surface of the surface-treated metal oxide particle material, granulation can be performed with the modifying material interposed between the surface-treated metal oxide particle material.

[0038] The granulation process is not particularly limited. Possible granulation methods include wet granulation using the dispersed slurry obtained from the dispersion process described above (e.g., spray drying, fluidized bed granulation, extrusion granulation, agitation granulation). Alternatively, granulation can also be performed using dry granulation methods (e.g., agitation granulation, tumbling granulation, compression granulation) using the dry powder obtained from the drying process described above.

[0039] The modified metal oxide particle material and its manufacturing method of the present invention will be described in detail below based on examples. [Test Example 1] (Preparation of Sample) Spherical silica manufactured by the VMC method (manufactured by Admatex Co., Ltd., model number: SO-C2, volume average particle size 0.5 μm) was used as the metal oxide particle material.

[0040] To 100 parts by mass of this metal oxide particle material, KBM-573 (manufactured by Shin-Etsu Chemical Co., Ltd.: N-phenyl-3-aminopropyltrimethoxysilane) was added as a surface treatment agent to perform a surface treatment to obtain a surface-treated metal oxide particle material. The amount of surface treatment agent added was 0.6 parts by mass per 100 parts by mass of the metal oxide particle material. N-phenyl-3-aminopropyl groups were introduced to the surface of the obtained surface-treated metal oxide particle material (surface treatment step).

[0041] A dispersion slurry was prepared by mixing 100 parts by mass of surface-treated metal oxide particle material with 64.4 parts by mass (80 mL) of methyl ethyl ketone (MEK). 0.5 parts by mass of a silicon-containing compound (Shin-Etsu Chemical Co., Ltd., KBM-202SS, monomer with a diphenyl functional group) was added as a modifying material, and the slurry was dispersed for 2 minutes using Creamix CLM-2.2S: M-Technique Co., Ltd. (17000 rpm) (dispersion step).

[0042] Subsequently, the powder was heated at 110°C for the time (m minutes) shown in Table 1 and dried (drying step). The resulting powder was then molded into a cylindrical shape of φ40 mm using a powder molding press. After that, the powder was crushed and passed through a first sieve with a mesh size of 900 μm and a second sieve with a mesh size of 600 μm. The powder that passed through the first sieve but not the second sieve was collected and used as the test sample for this test example. [Test Examples 2 and 3] Compared to Test Example 1, the test samples for this test example were prepared using the same procedure, except that the metal oxide particle material was changed to spherical silica manufactured by the VMC method (manufactured by Admatex Co., Ltd., model number: SO-C1, volume average particle size 0.3 μm), and the modifying material was changed from KBM-202SS to another surface treatment agent.

[0043] The modified materials used were KR-9218 (manufactured by Shin-Etsu Chemical Co., Ltd.: functional groups of methyl and phenyl groups, medium hardness) in Test Example 2 and KR-510 (manufactured by Shin-Etsu Chemical Co., Ltd.: functional groups of methyl and phenyl groups, high hardness) in Test Example 3.

[0044] It is known that the surface treatment agents (KR-9218 and KR-510) used in Test Examples 2 and 3, respectively, are silane compounds having methyl and phenyl groups, but their detailed chemical structures are not clear. [Test Examples 4-6] The test samples for these test examples were prepared using the same procedure as in Test Example 1, except that the mesh sizes of the first and second sieves were changed. Specifically, in Test Example 4, the mesh size of the first sieve was 3 mm and the mesh size of the second sieve was 200 μm; in Test Example 5, the mesh size of the first sieve was 5 mm and the mesh size of the second sieve was 200 μm; and in Test Example 6, the mesh size of the first sieve was 300 μm and the mesh size of the second sieve was 100 μm. [Comparative Examples 1-3] For Comparative Example 1, the particle material that passed through the second sieve in Test Example 1 was further passed through a third sieve with a mesh size of 100 μm. For Comparative Example 2, the particle material that passed through the second sieve in Test Example 2 was further passed through a third sieve with a mesh size of 100 μm. For Comparative Example 3, the particle material that passed through the second sieve in Test Example 3 was further passed through a third sieve with a mesh size of 100 μm.

[0045] For each test sample, the carbon content before washing (C content before washing), the carbon content after washing (C content after washing), the dielectric loss tangent (Df), and D10 and D90 were measured from the dry particle size distribution.

[0046] Df measurements were performed in accordance with JIS C 2138 (2007). Specifically, relative permittivity and dielectric loss tangent at 1 GHz were measured using a Keysight network analyzer (product name "E5071C") and the cavity resonator perturbation method. This measurement was performed in accordance with ASTM D2520 (JIS C 2565 (1992)).

[0047] Dry particle size distribution measurements were performed using a Mastersizer 3000 manufactured by Spectris Co., Ltd., and D10 and D50 were calculated. This measurement allowed us to determine the particle size distribution of the granulated material, rather than the particle size of the primary particles.

[0048] Furthermore, the degree of dispersion was measured using a particle gauge. The evaluation of the degree of dispersion using a particle gauge is a test conducted in accordance with JIS K 56000-2-5, and the particle gauge value correlates with the particle size of the aggregates. In other words, a larger particle gauge value indicates the formation of larger aggregates. The particle gauge was measured under two conditions: immediately after the preparation of the test sample and after heated storage. Heated storage was performed by leaving the test sample in a sealed container that prevents the passage of gases, etc., at an ambient temperature of 45°C for 50 hours.

[0049] Furthermore, the value of (dielectric loss tangent) / (specific surface area) (Df / specific surface area) for each test sample in the test example is calculated and shown in Table 1. As is clear from the table, when comparing Test Examples 1-3 with Comparative Examples 1-3, which are the same particle material as Test Examples 1-3 except that D10 and D90 are smaller, it was found that while Comparative Examples 1-3, which have smaller D10 and D90, showed suppressed aggregation with a particle gauge of 20 μm or less after heating and storage, all Comparative Examples 1-3 showed a particle gauge of 25 μm or more after heating and storage, indicating that aggregation progressed during storage.

[0050] In all three test samples obtained in the same manner except for a change in the surface treatment agent, the particle gauge value after heating and storage was reduced, but the reduction was particularly significant in Test Example 2.

[0051] Furthermore, in the test samples of Test Examples 4 to 6, which were obtained in the same manner as in Test Example 1 except for changing the mesh openings of the first and second sieves, although the D10 and D90 values ​​differed, it was found that when the particle size was within this range, the particle gauge after heating and storage was 20 μm or less, indicating that aggregation was suppressed.

Claims

1. A granulated material comprising a surface-treated metal oxide particle material having functional groups other than phenyl groups on its surface, and a modifying material consisting of a silicon-containing compound having phenyl groups, which adheres to the surface of the surface-treated metal oxide particle material, wherein the primary particle size is 0.01 μm or more and 5 μm or less, the D10 of the granulated material measured by dry method is 3 μm or more and 50 μm or less, the D90 is 50 μm or more and 1000 μm or less, and the surface area H (m²) per gram ２ A modified metal oxide particle material in which the C / H value calculated from the carbon content C (mass%) decreases by 0.001 or more after washing with methyl ethyl ketone, the particle size is 20 μm or less on a particle gauge, and the C / H value after washing is 0.07 or less.

2. The modified metal oxide particle material according to claim 1, wherein the particle size gauge after being left in a sealed container at 45°C for 50 hours is 20 μm or less.

3. The modified metal oxide particle material according to claim 1 or 2, wherein (dielectric loss tangent) / H is 0.0005 or less.

4. A modified metal oxide particle material according to any one of claims 1 to 3, which can be prepared by applying a modified material solution obtained by dissolving or dispersing the modified material in A mL of solvent to the surface-treated metal oxide particle material, and then heating and drying it at T°C for m minutes (where T × m ÷ A is 150 or less).

5. The modified metal oxide particle material according to any one of claims 1 to 4, wherein the silicon-containing compound constituting the modified material is a silane compound having a phenyl group, or a condensate of a silane compound having a phenyl group and a silane compound having a hydrocarbon group directly bonded to Si.

6. The silane compound having the phenyl group is represented by ((C ６ H ５ )X) ｎ -Si-OR （４－ｎ） , and the silane compound having a hydrocarbon group is represented by R ｎ -Si-OR （４－ｎ） The modified metal oxide particle material according to claim 5, which is represented by. (X is a direct bond, -(CH ２ ) ｑ - or -O-; q is an integer from 0 to 3; n is an integer from 1 to 3 independently selected for each molecule; R is a hydrocarbon group having 1 to 3 carbon atoms independently selected for each functional group) 7. The silicon-containing compound constituting the modified material is of the general formula (1): R1-O-(SiZ1Z2O) ｎ -(SiZ3Z4O) ｍ - A modified metal oxide particle material according to any one of claims 1 to 5, wherein R2 is (C ６ H ５ )X-;Z2-Z4 are each independent (C ６ H ５ )X-, a hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and -O which bonds with the other Z2 to Z4. ｒ - (CH ２ ) ｐ -O ｔ -; X is directly bonded, or - (CH ２ ) ｑ (either - or -O-; n and p are integers greater than or equal to 1; m is an integer greater than or equal to 0; q is an integer greater than or equal to 0 that is independently selected; r and t are independently selected from 0 or 1; R1 and R2 are independently selected hydrocarbon groups or alkoxy groups having 1 to 3 carbon atoms.) 8. The modified metal oxide particle material according to any one of claims 1 to 7, wherein the surface-treated metal oxide particle material is surface-treated with a silane compound.

9. A method for producing a modified metal oxide particle material according to any one of claims 1 to 8, comprising: a surface treatment step of surface-treating a metal oxide particle material with a silane compound to produce a surface-treated metal oxide particle material; a dispersion step of dispersing a silicon-containing compound having a phenyl group in a dispersion slurry obtained by dispersing the surface-treated metal oxide particle material in A mL of a dispersion medium; a drying step of drying the dispersion medium after the dispersion step by heating at T°C for m minutes to deposit a modified material consisting of the silicon-containing compound onto the surface of the surface-treated metal oxide particle material to produce a modified metal oxide particle material; and a granulation step performed simultaneously with or after the dispersion step of granulating the modified metal oxide particle material (wherein T × m ÷ A is 150 or less).

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