Metal oxide particle material and production method for same

Abstract

The present invention addresses the problem of providing a metal oxide particle material that has had coarse particles removed therefrom but has a large mode diameter. It was discovered that it is possible to perform effective classification by dispersion in a liquid and then passage through a sieve, and the present invention provides: a metal oxide particle material that is obtained in such a manner and has a mode diameter that is close to the size of coarse particles that are removed; and a production method for the metal oxide particle material. Specifically, this metal oxide particle material has a mode diameter of 3.0–9.0 μm, has a D50 of 2.5–8.0 μm, contains no more than 500 ppm of coarse particles that are 10 μm or larger, has a mode diameter / D99 of at least 0.32, and is at least 15% particles that have a particle diameter of 0.5–2.0 μm relative to the total mass.

Description

Metal oxide particle material and method for producing the same

[0001] The present invention relates to a metal oxide particulate material and a method for producing the same.

[0002] Resin compositions containing metal oxide particle fillers dispersed in a resin material are widely used for semiconductor packages. As semiconductor packages become smaller and their wiring becomes finer, there is a growing demand for precise removal of coarse particles with a particle size above a certain level (e.g., 10 μm or larger). Meanwhile, resin compositions containing dispersed metal oxide particles are desired to have high fluidity.

[0003] JP 2022-037681 A JP 2005-171208 A

[0004] One method for improving the fluidity of a resin composition is to increase the mode diameter, but increasing the mode diameter inevitably brings the particle size closer to that which is judged to be coarse particles.

[0005] In general, it is difficult to prepare metal oxide particle materials by removing coarse particles with a particle size close to the mode diameter. When attempting to classify coarse particles from raw materials using a sieve with openings corresponding to the size of the coarse particles, the size of the openings is close to the mode diameter, which can easily clog the sieve, resulting in significant issues with productivity and yield. Furthermore, classification methods that utilize the centrifugal force of airflow are less susceptible to clogging than sieves, but when classification is performed under conditions that allow for the removal of coarse particles, particles with particle sizes smaller than the coarse particles are also removed, resulting in a decrease in the mode diameter.

[0006] The present invention was completed in view of the above circumstances, and an object to be achieved is to provide a metal oxide particulate material from which coarse particles have been removed and which has a large mode diameter.

[0007] As a result of intensive research aimed at solving the above-mentioned problems, the inventors discovered that classification can be effectively carried out by passing the particles through a sieve while dispersed in a liquid, and completed an invention relating to a metal oxide particle material and a method for producing the same, in which the mode diameter obtained by this method is close to the size of the coarse particles to be removed.

[0008] That is, the metal oxide particulate material of the present invention, which solves the above-mentioned problems, has a mode diameter of 3.0 μm to 9.0 μm, a D50 of 2.5 μm to 8.0 μm, a content of coarse particles of 10 μm or more of 500 ppm or less, a mode diameter / D99 of 0.32 or more, a content of particles having a particle size of 0.5 μm to 2.0 μm of 15% or more based on the total mass, or a content of particles having a particle size of 0.5 μm to 1.0 μm of 2.0% or more based on the total mass.

[0009] The content of particles with a particle size of 0.5 μm to 1.0 μm is preferably 2.0% or more based on the total mass. The linseed oil absorption is preferably 1.4 g / 10 g or less. The viscosity of a dispersion of the 75% by mass of the cellulose acylate filled and dispersed in an epoxy resin as a dispersion medium at 25°C and a shear rate of 5 / s is preferably 250 Pa·s or less. Furthermore, the cellulose acylate is preferably surface-treated with a silicon-containing compound.

[0010] In particular, the specific surface area is 1.0 m ２ / g to 5.0m ２ / g. It is also preferable that the U content is 2.0 ppb or less and the Th content is 10.0 ppb or less. It is also preferable that, based on the total mass, particles with a particle size in the range of 0.2 μm to 0.5 μm account for 2.0% or more and particles with a particle size in the range of 0.1 μm or less account for 0.1% or more.

[0011] The method for producing a metal oxide particulate material of the present invention that solves the above-mentioned problems is a method for producing the above-mentioned metal oxide particulate material of the present invention, and includes: a metal oxide raw particle material preparation step in which a raw particle material made of a metal oxide is introduced into a high-temperature atmosphere to melt and spheroidize, or a raw particle material made of a metal material contained in the metal oxide is introduced into a high-temperature oxidizing atmosphere to deflagrate and spheroidize, thereby preparing a metal oxide raw particle material; a classification step in which a dispersion of the metal oxide raw particle material in a dispersion medium is passed through a sieve to classify the dispersion; and a surface treatment step in which a surface treatment is performed with the silicon-containing compound after the metal oxide raw particle material preparation step.

[0012] The metal oxide particle material and its manufacturing method of the present invention will be described in detail below based on the following embodiments. The metal oxide particle material of this embodiment is a particle material that can be suitably used as a filler for semiconductor packaging materials by dispersing it in a resin material. Examples of semiconductor packaging materials include sealing materials, materials for printed wiring boards, electronic substrates, solder resists, interlayer insulating films, build-up materials, FPC adhesives, die-bonding materials, underfills, ACF, ACP, NCF, and NCP. In this specification, the term "particle size" refers to the volume average particle size for an aggregate of metal oxide particle material, and refers to the particle size of each individual particle when referring to individual metal oxide particle material.

[0013] The numerical range "x to y" described in this specification includes the lower limit x and the upper limit y. Furthermore, a new numerical range can be formed by arbitrarily combining these upper and lower limits, as well as the numerical values ​​listed in the specification or examples. The new numerical range can also be a range that excludes one or both of the upper and lower limits. For example, a range exceeding x or a range less than y can be adopted. Furthermore, 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. (Metal Oxide Particle Material) The metal oxide particle material of this embodiment is composed of a metal oxide. Examples of metal oxides include silica, alumina, zirconia, titania, composite oxides thereof, and mixtures thereof.

[0014] The metal oxide particulate material of this embodiment has a mode diameter of 3.0 μm to 9.0 μm, with upper limits of 8.0 μm, 7.0 μm, and 6.0 μm, and lower limits of 3.4 μm, 3.6 μm, and 4.2 μm. These upper and lower limits can be combined arbitrarily. The mode diameter in this embodiment is the most frequent value obtained from a volume-based frequency distribution measured by a laser diffraction / scattering method. The D50 and D99 values ​​described below are also calculated using the same frequency distribution.

[0015] The metal oxide particle material of this embodiment has a D50 of 2.5 μm to 8.0 μm, with upper limits of 7.0 μm, 6.0 μm, and 5.0 μm, and lower limits of 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm, and 3.2 μm. These upper and lower limits can be combined arbitrarily. D50 is preferably smaller than the mode diameter. Note that D50 is the particle size at which the volume becomes 50% when the particle sizes are accumulated sequentially from the smallest to the largest based on the total volume. D99 is the particle size at which the accumulated volume becomes 99%.

[0016] The metal oxide particle material of this embodiment has a mode diameter / D99 of 0.32 or more, preferably 0.33 or more, 0.34 or more, or 0.35 or more. A larger value results in a relatively larger proportion of particles with large particle diameters. In order to increase the mode diameter / D99 value, it is preferable to perform the classification operation with high classification efficiency.

[0017] Furthermore, in the metal oxide particle material of this embodiment, the content A of particles having a particle size of 0.5 μm to 2.0 μm is 15% or more based on the total mass. The lower limit of the content A can be 16%, 17%, 18%, 19%, 20%, or 25%. By setting the content A within this range, the fluidity when applied to a resin composition can be improved.

[0018] The content B of particles having a particle size of 0.5 μm to 1.0 μm is 2.0% or more based on the total mass. The lower limit of the content B can be 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, or 10%. By setting the content B within this range, the fluidity when applied to a resin composition can be improved.

[0019] Furthermore, the metal oxide particulate material of this embodiment preferably has a D50 / (D50 converted from specific surface area) of 2.4 to 8.0. Here, (D50 converted from specific surface area: hereinafter referred to as "D50SSA") is a value calculated from the specific surface area (SSA) measured by the BET method using nitrogen. It is a value calculated by D50SSA = 6 / SSA / (specific gravity of metal oxide particulate material). When the metal oxide is silica, the specific gravity is 2.25 g / cm. ３The lower limit of D50 / D50SSA can be 2.5, 2.6, or 2.7, and the upper limit can be 7.0, 6.5, or 6.0.

[0020] The metal oxide particulate material of the present invention preferably has a content of coarse particles of 10 μm or more of 500 ppm or less, 400 ppm or less, 300 ppm or less, or 200 ppm or less. By reducing the content of coarse particles and increasing the value of mode diameter / D99, it is possible to obtain a metal oxide particulate material having a relatively large particle size while limiting the amount of coarse particles.

[0021] The metal oxide particle material of this embodiment preferably contains, based on the total mass, 2.0% or more particles having a particle size in the range of 0.2 μm to 0.5 μm (medium-sized particles) and 0.1% or more particles having a particle size in the range of 0.1 μm or less (small-sized particles).

[0022] The lower limit of the content of medium-sized particles is 3.0%, 4.0%, or 5.0%, and the upper limit is 40%, 50%, or 60%, and these upper and lower limit values ​​can be combined in any combination. The lower limit of the content of small-sized particles is 0.2%, 0.3%, or 0.4%, and the upper limit is 3.0%, 5.0%, or 10.0%, and these upper and lower limit values ​​can be combined in any combination.

[0023] The metal oxide particulate material of this embodiment has a linseed oil absorption of 1.4 g / 10 g or less, preferably 1.3 g / 10 g or less, 1.2 g / 10 g or less, or 1.1 g / 10 g or less. The lower the linseed oil absorption, the higher the packing ability. In order to reduce the linseed oil absorption, it is preferable to have a somewhat broad particle size distribution.

[0024] The metal oxide particle material of this embodiment has a viscosity of 250 Pa s or less, preferably 230 Pa s or less, 210 Pa s or less, or 190 Pa s or less when dispersed in an epoxy resin at a concentration of 75% by mass. The viscosity was measured by mixing 18 g of the sample with 6 g of epoxy resin (ZX1059) and using a rheometer (ARES-G2, manufactured by TA Instruments). The viscosity measurement conditions were 25°C and a shear rate of 5 (1 / s).

[0025] The metal oxide particulate material of this embodiment is preferably spherical, and those having a sphericity of 0.9 or more, 0.95 or more, 0.98 or more, or 0.99 or more can be used. A higher sphericity tends to improve packing properties and also tends to reduce the viscosity of the high-concentration, high-dispersion slurry composition. Sphericity can be determined by taking a photograph with an SEM and calculating the area and perimeter of the observed particles as follows: (sphericity) = {4π × (area) ÷ (perimeter)} ２ The closer to 1 the particle size is, the closer it is to a perfect sphere. Specifically, the average value measured for 100 particles using image analysis software (Asahi Kasei Engineering Co., Ltd.: A-zo-kun) is used.

[0026] The metal oxide particulate material of this embodiment is surface-treated with a silicon-containing compound. The silicon-containing compound is not particularly limited, but may be a silane compound or a silazane compound. By performing the surface treatment, the surface properties of the filler material can be made preferable.

[0027] For example, when mixed into a resin material, the polymer may be hydrophobized (e.g., a phenyl group or a hydrocarbon group) to improve its affinity with the resin material, or a functional group reactive with the resin (e.g., a vinyl group, an epoxy group, an acrylic group, or a methacrylic group) may be introduced.

[0028] Examples of the silane compound include so-called silane coupling agents having SiH, SiOH, or SiOR (R is a hydrocarbon group), and examples include silane compounds in which any functional group is bonded to Si.

[0029] Examples of the optional functional group include hydrocarbon groups (alkyl groups (methyl, ethyl, propyl, butyl, etc.), alkenyl groups (vinyl, ethenyl, propenyl, etc.), phenyl groups, amino groups, phenylamino groups, acrylic groups, methacrylic groups, epoxy groups, styryl groups, silicones, and combinations thereof. As the silane compound, one type can be used for treatment, or two or more types can be used in combination for treatment. When two or more types are used in combination for surface treatment, multiple types of surface treatment agents can be mixed for surface treatment, or multiple types of surface treatment agents can be used sequentially for surface treatment.

[0030] Preferred silane compounds include those having an epoxy group (3-glycidoxypropylmethyldiethoxysilane: KBE-402: Shin-Etsu Chemical Co., Ltd. (hereinafter the same), 3-glycidoxypropyltriethoxysilane: KBE-403, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane: KBM-303, 3-glycidoxypropylmethyldimethoxysilane: KBM-402, 3-glycidoxypropyltrimethoxysilane: KBM-403, 8-glycidoxypropylmethyldimethoxysilane: KBM-403, 8-glycidoxypropylmethyldimethoxysilane: KBM-402, 8-glycidoxypropyltrimethoxysilane: KBM-403, 8-glycidoxypropylmethyldimethoxysilane: KBM-403, 8-glycidoxypropylmethyldimethoxysilane: KBM-402, 8-glycidoxypropyltrimethoxysilane: KBM-403, 8-glycidoxypropylmethyldimethoxysilane: KBM-402, 8-glycidoxypropyltriethoxy ...ethoxysilane: KBM-402, 8-glycidoxypropyltriethoxysilane: KBM-403, 8-glycidoxypropylmethyldiethoxysilane: KBM-40 Examples include those having an acrylic group (3-acryloxypropyltrimethoxysilane: KBM-4803), those having an acrylic group (3-acryloxypropyltrimethoxysilane: KBM-5103, multifunctional group type (organic chain type): X-12-1048, multifunctional group type (organic chain type): X-12-1050), those having an amino group (N-phenyl-3-aminopropyltrimethoxysilane: KBM-573), and those having a methacryl group (3-methacryloxypropyltrimethoxysilane: KBM-503).

[0031] An example of a silazane compound is 1,1,1,3,3,3-hexamethyldisilazane. The surface treatment can be carried out using one or more of these silicon-containing compounds in combination. Furthermore, surface treatment can be carried out using a compound other than the silicon-containing compound simultaneously with the silicon-containing compound, or before or after treatment with the silicon-containing compound.

[0032] The amount of surface treatment is not particularly limited, but the surface treatment can be carried out so as to achieve the desired properties. In addition, when the surface treatment agent is a substance that reacts with functional groups (such as OH groups) on the surface of the filler material, the amount of the surface treatment agent can be selected according to the amount of functional groups present on the surface of the filler material (the entire amount, half the amount, double the amount, etc. of the functional groups on the surface).

[0033] The metal oxide particulate material of this embodiment has a specific surface area of ​​1.0 m ２ / g to 5.0m ２ / g, and the lower limit is 1.5m ２ / g, 2.0 m ２ / g, 2.5m ２ / g, with an upper limit of 4.5 m ２ / g, 4.0 m ２ / g, 3.5m ２ / g. The specific surface area can be reduced by smoothing the particle surface by removing irregularities and pores, or by increasing the sphericity. The specific surface area is measured by the BET method using nitrogen gas.

[0034] In the metal oxide particle material of this embodiment, the content of U as impurities is preferably 2.0 ppb or less, or even 1.0 ppb, and the content of Th is preferably 10.0 ppb or less, or even 5 ppb or less, and the total content of U and Th is preferably 10 ppb or less, or even 5 ppb or less, more preferably 3 ppb or less, and particularly preferably 1 ppb or less.

[0035] The metal oxide particulate material of this embodiment may be in a dry state or may be a slurry composition dispersed in a liquid dispersion medium. Examples of the dispersion medium include water and organic solvents. Examples of organic solvents include alkanes (e.g., hexane), alcohols (e.g., methanol, ethanol, propanol), ketones (e.g., acetone, cyclohexanone), and aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, xylene), used alone or in mixtures. (Method for Producing a Metal Oxide Particulate Material) The method for producing a metal oxide particulate material of this embodiment is a method for producing the metal oxide particulate material of this embodiment described above, and includes a metal oxide raw particle material preparation step, a classification step, a surface treatment step, and other steps selected as necessary. -Metal Oxide Raw Particle Material Preparation Step The metal oxide raw particle material preparation step is a step of preparing a metal oxide raw particle material by either introducing a raw particle material made of a metal oxide into a high-temperature atmosphere and melting and spheroidizing it (melting method) or introducing a raw particle material made of a metal material contained in the metal oxide into a high-temperature oxidizing atmosphere and deflagrating and spheroidizing it (deflagration method: VMC method).

[0036] The melting method is a method for preparing spherical metal oxide raw particle material by introducing raw particle material made of a metal oxide that constitutes the metal oxide particle material into a high-temperature atmosphere such as a flame, melting it, spheroidizing it, and cooling it. The raw particle material can be prepared by powdering a material made of a metal oxide by pulverization or the like, or by using a particle material obtained by the VMC method described below, either as is or after classification.

[0037] The VMC method is a method for obtaining a metal oxide raw particle material made of a metal oxide by deflagrating a metal particle material made of a metal that constitutes a metal oxide (metallic silicon for silica, metallic aluminum for alumina) in a high-temperature oxidizing atmosphere and then spheroidizing it by rapid cooling. Classification process: In the classification process, the metal oxide raw particle material is dispersed in a liquid dispersion medium and passed through a sieve to classify it. Prior to classification in the dispersion medium, preliminary classification may be performed by sieving in a dry state or centrifugal classification. For example, a sieve with a mesh size of around 10 μm is ultimately used for passing the dispersion through to remove coarse particles (particles with a particle size of 10 μm or more). However, the dispersion can also be passed through a sieve with a mesh size larger than 10 μm in a dry state or by centrifugal classification.

[0038] Furthermore, before finally passing the dispersion medium through a sieve with openings of about 10 μm, the dispersion medium may be passed through a sieve with openings larger than 10 μm, or centrifugal classification may be performed with a particle size larger than 10 μm as the classification point (preliminary classification step). By performing the preliminary classification step, the classification operation of passing through a sieve with openings of about 10 μm can be performed efficiently.

[0039] That is, the operation of passing through a sieve may be performed once or twice or more times. When the operation of passing through a sieve twice or more is performed, the sieves through which the material is passed may have the same or different mesh sizes. When passing through sieves with different mesh sizes, it is preferable to pass the material through a sieve with a larger mesh size first.

[0040] After the classification step, the material may remain in the form of a dispersion or may be dried. The dispersion medium may be replaced with another organic solvent or a liquid resin material from the dispersion state. If aggregates are formed upon drying, a crushing step is preferably performed. Furthermore, before or after the classification step, particles with a particle size ranging from 0.2 μm to 0.5 μm (medium-sized particles) or particles with a particle size ranging from 0.1 μm or less (small-sized particles) may be added. The medium-sized particles and small-sized particles are preferably composed of the metal oxide that constitutes the metal oxide particle material to be produced. Surface Treatment Step: This is a step in which the metal oxide raw particle material is surface-treated directly or after the classification step. The surface treatment may be performed in either a dry state or in a dispersion state. The surface treatment is performed using the silicon-containing compound described above. The silicon-containing compound is contacted with the surface of the particle material directly, in a state dissolved in some liquid, or in a heated, vaporized state. Heating is preferably performed after contact.

[0041] The type and amount of silicon-containing compound to be reacted are not particularly limited, but are appropriately adjusted depending on the application of the metal oxide particulate material to be produced. For example, when a metal oxide particulate material is used as a resin composition dispersed in a resin material, a silicon-containing compound having a functional group with high affinity or high reactivity with the resin material can be used and reacted in an amount sufficient to exhibit sufficient performance. For example, based on the amount of OH groups present on the surface of the particles before reaction, an amount sufficient to react with the entire amount, half amount, or double amount can be used. Surface treatment can also be performed using compounds other than silicon-containing compounds. (Filler for Semiconductor Mounting Material and Semiconductor Mounting Material) The semiconductor mounting material of this embodiment is a material in which the metal oxide particulate material of this embodiment is dispersed in a resin material. The resin material is not particularly limited, but examples include epoxy resin and silicone resin. In particular, a pre-cured thermosetting resin is preferably used. The filler for semiconductor mounting material is preferably contained in the resin material at approximately 20% to 92% by weight, more preferably approximately 40% to 90%, and even more preferably approximately 60% to 88% by weight.

[0042] The metal oxide particulate material of the present invention will be described in detail below with reference to examples. (Example 1) Crushed silica (volume average particle size 4.5 μm) was introduced into a flame, melted, and spheroidized to obtain spherical metal oxide raw particle material (metal oxide raw particle material preparation step). The obtained metal oxide raw particle material was dispersed in water as a dispersion medium to obtain a dispersion liquid (dispersion slurry) with a solid content concentration of 20 mass %. This dispersion liquid was passed through a sieve with 10 μm openings to remove coarse particles with a particle size of 10 μm or more (classification step).

[0043] The classified slurry was dried using a dryer and crushed using a jet mill. To the crushed material, 30% of the total mass of medium-sized particles made of silica with a particle size distribution of 0.2 to 0.5 μm and 1% of the total mass of small-sized particles made of silica with a particle size distribution of 100 nm or less were added. The surface was then treated with epoxysilane, and the peak of the silica surface silanol group (3740 cm) in the FT-IR spectrum measured by the diffuse reflectance method was detected. －１The metal oxide particulate material was used as the test material for this example, after it was confirmed that the crystalline ... The metal oxide particulate material obtained in the same manner as in Example 1, except that medium-sized particles having a particle size distribution of 0.5 to 1.5 μm were added at a ratio of 30% based on the total mass, was used as the test sample for this comparative example. (Comparative Example 2) The metal oxide particulate material produced in the same manner as in Example 1, except that the classification step involved centrifugal classification using the centrifugal force of an airflow while the metal oxide raw particle material obtained in the metal oxide raw particle material preparation step was kept dry to reduce coarse particles with a particle size of 20 μm or more and fine particles with a particle size of 1 μm or less, was used as the test sample for this comparative example. (Comparative Example 3) The metal oxide particulate material obtained in the same manner as in Example 1, except that no medium-sized or small-sized particles were added and no surface treatment step was performed, was used as the test sample for this comparative example. (Comparative Example 4) The metal oxide particulate material obtained in the same manner as in Comparative Example 2, except that no medium-sized or small-sized particles were added, was used as the test sample for this comparative example. (Comparative Example 5) The sample described in Example 1 of Patent Document 1 (JP 2022-037681 A) was used as the test sample for this comparative example. For reference, paragraphs 0042 to 0045 of Patent Document 1 are cited below.

[0042] <Preparation of Amorphous Silica Powder> Amorphous silica powders of preparation examples of the present invention were prepared by the following procedure.Commercially available amorphous silica was used as the raw material. This raw material had one mode diameter peak in the range of 1 to 10 μm.

[0043] [Coarse Particle Classification] First, the raw material amorphous silica powder was subjected to coarse particle classification to remove large particle diameters. The cumulative distribution of particles having a particle diameter of 13 μm or more on the sieve is shown in Table 1. In the examples, the cumulative distribution of particles having a particle diameter of 13 μm or more on the sieve was 0.0 mass%.

[0044] [Fine Particle Classification] Next, in some examples, the frequency of particles having a particle diameter of 0.50 to 1.83 μm was adjusted by a method of cutting off the fine powder side using a precision air classifier. The frequency of particles having a particle diameter of 0.50 to 1.83 μm is shown in Table 1. In the examples, the frequency of particles having a mode diameter in the range of 1 to 10 μm was 9.3 to 13.6 volume%.

[0045] [Ultrafine Powder Blending] Next, in the Examples, amorphous silica powder having a smaller particle size (ultrafine powder having a particle size (median diameter) of 0.10 μm or 0.14 μm) compared to the amorphous silica powder obtained in the steps up to fine powder classification was blended in at the internal addition ratios shown in Table 1. In this blending, a particle size that frequently appeared in the range of 0.1 to 0.3 μm was selected for each Example. The blending was also performed so that a peak different from the peak having a maximum value in the range of 1 to 10 μm appeared. In the Example with a particle size of 0.14 μm, the maximum value of the peak containing particles with a particle size of less than 0.50 μm was in the range of 0.1 to 0.3 μm. (Comparative Example 6) A metal oxide raw particle material (volume average particle size 2.0 μm) made of silica obtained by the VMC method was dispersed in isopropyl alcohol, and coarse particles were removed using a sieve with 5 μm openings to obtain a metal oxide particle material. The obtained metal oxide particle material was dried, and then small particles made of silica with a particle size of 50 nm were added in an amount of 0.5% based on the total mass to prepare a test sample for this comparative example.

[0044] (Evaluation) For each example and comparative example, the mode diameter, D50, D99, amount of coarse particles, value of mode diameter / D99, linseed oil absorption, packing property, fluidity, specific surface area, amount of U and Th, and D50 / D50SSA were measured or calculated, and the results are shown in Table 1.

[0045] The mode diameter, D50, and D99 were measured by laser diffraction / scattering. The amount of coarse particles was calculated by measuring the mass of particles remaining on a 10 μm mesh sieve after passing through it. The linseed oil absorption was measured by adding linseed oil drop by drop to a 10 g test sample, and the amount of linseed oil added (ml) when fluidization was confirmed visually.

[0046] The packing property was determined by whether a slurry could be formed when the test sample was dispersed in ZX-1059 as a dispersion medium so that the dispersion was 75% of the total mass. The fluidity was measured using the viscosity measurement method described in the above embodiment. The specific surface area was measured using the BET method using nitrogen gas.

[0047] As is clear from Table 1, Examples 1, 2, 3, 4 and 5, which were subjected to wet sieving, had better fluidity than the test sample of Comparative Example 1, which was subjected to dry classification. Note that the test samples of Comparative Examples 2, 3 and 5, which were subjected to dry classification using a classification point far larger than 10 μm, the lower limit of the particle size of coarse particles, showed fluidity values ​​comparable to those of Examples 1, 2, 3, 4 and 5, but the amount of coarse particles was naturally excessive.

[0048] In Comparative Example 3, the content of particles having a particle size in the range of 0.5 to 2 μm (content A) was less than 15%, so the viscosity was high.

[0049] In Comparative Example 4, the content of small and medium diameter particles was low, so the fluidity value was high and the linseed oil absorption was large. Therefore, the filling ability was insufficient.

[0050] In Comparative Examples 1, 5 and 6, the mode diameter / D99 value was small, and therefore the fluidity was insufficient.

[0051] Furthermore, when the results of calculating the specific surface area (SSA) from D50 were compared with the actually measured SSA, it was found that the SSA calculated from D50 was significantly smaller than the actually measured SSA for the test samples containing medium-sized particles and small-sized particles, such as those in Examples and Comparative Examples 1 and 2. These test samples had low viscosity.

[0052] In contrast, in Comparative Example 3 and subsequent Comparative Examples in which no medium-sized particles or small-sized particles were added, the difference between the SSA calculated from D50 and the actually measured SSA was small, and the viscosity was relatively high.

Claims

1. A metal oxide particle material having a mode diameter of 3.0 μm to 9.0 μm, a D50 of 2.5 μm to 8.0 μm, a content of coarse particles of 10 μm or more of 500 ppm or less, a mode diameter / D99 ratio of 0.32 or more, and a content of particles of 0.5 μm to 2.0 μm in particle size of 15% or more based on the total mass, and / or a content of particles of 0.5 μm to 1.0 μm in particle size of 3.0% or more based on the total mass.

2. The metal oxide particulate material according to claim 1, wherein D50 / (D50 converted from specific surface area) is 2.4 to 8.

0.

3. The metal oxide particle material according to claim 1 or 2, which has a linseed oil absorption of 1.4 g / 10 g or less.

4. A metal oxide particle material according to any one of claims 1 to 3, wherein the viscosity of a dispersion liquid filled and dispersed at 75 mass% in ZX-1059 as a dispersion medium at 25°C and a shear rate of 5 / s is 250 Pa·s or less.

5. The metal oxide particulate material according to any one of claims 1 to 4, which has been surface-treated with a silicon-containing compound.

6. Specific surface area is 1.0 m ２ / g to 5.0m ２ The metal oxide particulate material according to any one of claims 1 to 5, wherein the SiO2 content is 1 / g.

7. The metal oxide particulate material according to any one of claims 1 to 6, wherein the U content is 2.0 ppb or less and the Th content is 10.0 ppb or less.

8. A metal oxide particle material according to any one of claims 1 to 7, containing, based on the total mass, 2.0% or more of particles having a particle size in the range of 0.2 μm to 0.5 μm and 0.1% or more of particles having a particle size in the range of 0.1 μm or less.

9. A method for producing a metal oxide particulate material according to any one of claims 1 to 8, comprising: a metal oxide raw particle material preparation step of preparing a metal oxide raw particle material by either introducing a raw particle material made of a metal oxide into a high-temperature atmosphere to melt and spheroidize it, or introducing a raw particle material made of a metal material contained in the metal oxide into a high-temperature oxidizing atmosphere to deflagrate and spheroidize it; a classification step of passing a dispersion of the metal oxide raw particle material in a dispersion medium through a sieve to classify it; and a surface treatment step of performing a surface treatment with the silicon-containing compound after the metal oxide raw particle material preparation step.

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