Spherical Silica Powder

Abstract

This spherical silica powder is configured such that when S1 is the sphericity at a particle diameter of 5 μm to less than 10 μm, S2 is the sphericity at a particle diameter of 10 μm to less than 20 μm, S3 is the sphericity at a particle diameter of 20 μm to less than 30 μm, S4 is the sphericity at a particle diameter of 30 μm to less than 45 μm, and S5 is the sphericity at a particle diameter of 45 μm or larger, as measured in the spherical silica powder by using a wet flow image analysis device, at least two values among S1, S2, S3, S4 and S5 are 0.74 or higher.

Description

[Technical Field]

[0001] The present invention relates to a spherical silica powder. [Background technology]

[0002] Various developments have been made so far regarding spheres. For example, a technique described in Patent Document 1 is known as a technique of this type. Patent Document 1 describes a method for obtaining molten spherical silica by injecting a siliceous raw material powder into a flame to melt it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-261328 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it has been found that the fused spherical silica described in Patent Document 1 has room for improvement in terms of fluidity. [Means for solving the problem]

[0005] After further investigation, the inventors discovered that the flowability can be improved by appropriately controlling the sphericity of the spherical silica powder in each particle size class, and thus completed the present invention.

[0006] According to one aspect of the present invention, there is provided the following spherical silica powder. 1. When the sphericity of the spherical silica powder measured using a wet flow image analyzer is S1, the sphericity of the particle diameter of 5 μm or more and less than 10 μm is S2, the sphericity of the particle diameter of 10 μm or more and less than 20 μm is S3, the sphericity of the particle diameter of 20 μm or more and less than 30 μm is S4, and the sphericity of the particle diameter of 30 μm or more and less than 45 μm is S5. At least two of S1, S2, S3, S4, and S5 are 0.74 or greater; Spherical silica powder. 2. The spherical silica powder according to 1., The average sphericity calculated from the average values ​​of S1, S2, S3, S4, and S5 (excluding values ​​with a value of 0) is S AVE Then, S AVE is 0.77 or more. 3. The spherical silica powder according to 2., In the volume frequency particle size distribution of the spherical silica powder measured by the wet laser diffraction scattering method, the particle size at which the cumulative value reaches 50% is defined as D 50 (μm) When S AVE and D 50 But 0.01 / μm ≦S AVE / D 50 ≦0.1 / μm The spherical silica powder is configured to satisfy the above. 4. The spherical silica powder according to any one of 1. to 3., The compacted bulk density, measured by procedure B below, is 1.2 g / cm 3 More than 1.6g / cm 3 The following is a spherical silica powder. (Step B) The spherical silica powder was allowed to fall naturally from a height of 25 cm at a rate of 5 to 10 g per minute, and then dropped to a height of 100 cm. 3 Prepare a heaping cup by pouring the contents into the measuring cup and continuing until it overflows. Next, for the heaping cup, without tapping, the amount overflowing on the top of the cup was leveled off, and then the mass (g) of the spherical silica powder filled in the cup was measured, and the loose bulk density (g / cm 3 ) is calculated. On the other hand, for the heaping cup, after tapping it up and down 180 times (stroke length 2 cm, 1 second / time), the amount that overflowed onto the top of the cup was leveled off, and the mass (g) of the spherical silica powder filled in the cup was measured, and the compacted bulk density (g / cm3 ) is calculated. 5. 1.~4. one of The spherical silica powder according to When the loose bulk density measured by the following procedure B is A and the hard bulk density is P, A spherical silica powder having a degree of compression calculated based on ((PA) / P) x 100 of 15% or more and 50% or less. (Step B) The spherical silica powder was allowed to fall naturally from a height of 25 cm at a rate of 5 to 10 g per minute, and then dropped to a height of 100 cm. 3 Prepare a heaping cup by pouring the contents into the measuring cup and continuing until it overflows. Next, for the heaping cup, without tapping, the amount overflowing on the top of the cup was leveled off, and then the mass (g) of the spherical silica powder filled in the cup was measured, and the loose bulk density (g / cm 3 ) is calculated. On the other hand, for the heaping cup, after tapping it up and down 180 times (stroke length 2 cm, 1 second / time), the amount that overflowed onto the top of the cup was leveled off, and the mass (g) of the spherical silica powder filled in the cup was measured, and the compacted bulk density (g / cm 3 ) is calculated. 6. The spherical silica powder according to any one of 1. to 5., In the volume frequency particle size distribution measured by the wet laser diffraction scattering method, the particle size at which the cumulative value reaches 10% is defined as D 10 (μm) The particle diameter at which the cumulative value reaches 50% is D 50 (μm) The particle diameter at which the cumulative value reaches 97% is D 97 (μm) When (D 97 -D 10 ) / D 50 is 1.0 or more and 10.0 or less. 7. The spherical silica powder according to any one of 1. to 6., In the volume frequency particle size distribution measured by the wet laser diffraction scattering method, the particle diameter at which the cumulative value reaches 50% is defined as D 50 (μm) The particle diameter at which the cumulative value reaches 97% is D 97 (μm) When D 97 / D 50 is 2.0 or more and 30.0 or less. [Effects of the Invention]

[0007] According to the present invention, a spherical silica powder having excellent flowability is provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the configuration of a thermal spraying device used to produce spherical silica powder. DETAILED DESCRIPTION OF THE INVENTION

[0009] The spherical silica powder of this embodiment will be outlined below.

[0010] The spherical silica powder of this embodiment is configured so that at least two of S1, S2, S3, S4, and S5 are 0.74 or more, where S1 is the sphericity for a particle diameter of 5 μm or more and less than 10 μm, S2 is the sphericity for a particle diameter of 10 μm or more and less than 20 μm, S3 is the sphericity for a particle diameter of 20 μm or more and less than 30 μm, S4 is the sphericity for a particle diameter of 30 μm or more and less than 45 μm, and S5 is the sphericity for a particle diameter of 45 μm or more, as measured using a wet flow image analyzer.

[0011] At least two of S1, S2, S3, S4, and S5 are 0.74 or more, preferably 0.80 or more, and more preferably 0.84 or more, thereby improving the fluidity.

[0012] Furthermore, among S1, S2, S3, S4, and S5, at least two, preferably three, and more preferably four of them satisfy a value of 0.74 or more, thereby improving the fluidity.

[0013] The average sphericity calculated from the average values ​​of S1, S2, S3, S4, and S5 (excluding values ​​with a value of 0) is S AVE The median diameter of the spherical silica powder measured using a wet flow image analyzer is D 50 (μm).

[0014] S AVEThe lower limit of S is, for example, 0.77 or more, preferably 0.82 or more, and more preferably 0.87 or more. This can improve the fluidity. AVE The upper limit may be set to, for example, 0.99 or less.

[0015] The sphericity of the spherical silica powder can be measured according to the following procedure A under conditions of room temperature of 25°C and humidity of 60%. The obtained spherical silica powder is measured using a wet flow image analyzer (FPIA-3000, manufactured by Sysmex Corporation) for the following sphericity: S1 for particle diameters of 5 μm or more and less than 10 μm, S2 for particle diameters of 10 μm or more and less than 20 μm, S3 for particle diameters of 20 μm or more and less than 30 μm, S4 for particle diameters of 30 μm or more and less than 45 μm, and S5 for particle diameters of 45 μm or more. The sphericity of each particle size class is the square of the circularity of each particle size class.

[0016] In this embodiment, for example, by appropriately selecting the raw material components of the spherical silica powder and the manufacturing method of the spherical silica powder, the sphericity and S AVE , and D 50 Among these, for example, appropriate control of melting flame conditions such as raw material supply amount, raw material particle size, flame temperature, combustible gas, combustion support gas, and dispersion gas can be used to control the sphericity, S in each of the particle size classes S1, S2, S3, S4, and S5. AVE , and D 50are cited as factors for setting the desired numerical range. For example, (i) the sphericity increases when the amount of raw material supplied is reduced, and decreases when it is increased, (ii) the sphericity increases when the particle sizes of the multiple raw materials are close to the average particle size, and decreases as the particle sizes deviate from that range, (iii) the sphericity increases as the flame temperature increases, and decreases as the temperature decreases, (iv) the sphericity increases as the temperature of the combustible gas increases, and decreases as the temperature decreases, (v) the sphericity increases as the amount of combustion support gas is closer to the stoichiometric ratio, and decreases as the particle sizes deviate from that range, and (vi) the introduction of a dispersion gas appropriately reduces coalescence and increases the sphericity.

[0017] The spherical silica powder of this embodiment may be configured so that the compressibility calculated based on ((PA) / P)) × 100, where A is the loose bulk density and P is the packed bulk density, measured by the following procedure B, is, for example, 15% or more and 50% or less.

[0018] The upper limit of the degree of compression is, for example, 50% or less, preferably 40% or less, and more preferably 30% or less, which can improve the fluidity.

[0019] The lower limit of the compacted bulk density (P) is, for example, 1.2 g / cm 3 or more, preferably 1.25 g / cm 3 More preferably, 1.3 g / cm 3 This makes it possible to improve the handling characteristics. The upper limit of the compacted bulk density (P) is, for example, 1.6 g / cm 3 or less, preferably 1.5 g / cm 3 or less, more preferably 1.4 g / cm 3 This improves the mixing ability with the resin.

[0020] The loose bulk density, packed bulk density, and compressibility of spherical silica powder can be measured according to the following procedure B under conditions of room temperature of 25°C and humidity of 55%. First, spherical silica powder was allowed to fall naturally from a height of 25 cm at a rate of 5 to 10 g per minute, and then dropped to a height of 100 cm. 3Prepare a heaping cup by pouring the contents into the measuring cup and continuing until it overflows. Next, for the heaping cup, without tapping, the amount overflowing on the top of the cup was leveled off, and then the mass (g) of the spherical silica powder filled in the cup was measured, and the loose bulk density (g / cm 3 ) is calculated. On the other hand, for the heaping cup, after tapping it up and down 180 times (stroke length 2 cm, 1 second / time), the amount that overflowed onto the top of the cup was leveled off, and the mass (g) of the spherical silica powder filled in the cup was measured, and the compacted bulk density (g / cm 3 ) is calculated.

[0021] The volume frequency particle size distribution of the spherical silica powder is measured by a wet laser diffraction scattering method, and the particle size at which the cumulative value reaches 10% in the volume frequency particle size distribution is defined as D 10 The particle diameter at which the cumulative value reaches 50% is D 50 The particle diameter at which the cumulative value reaches 97% is D 97 Let's say.

[0022] S AVE and D 50 But 0.01 / μm ≦S AVE / D 50 ≦0.1 / μm may be configured to satisfy the following. S AVE / D 50 The lower limit of, for example, 0.01 / μm or more, preferably 0.015 / μm or more, more preferably 0.023 / μm This makes it possible to improve the liquidity. S AVE / D 50 of The upper limit is, for example, 0.1 / μm Less than or equal to 0.75, preferably / μm Less than or equal to 0.5, more preferably / μm This improves liquidity.

[0023] (D 97 -D10 ) / D 50 The upper limit of is, for example, 10.0 or less, preferably 7.0 or less, and more preferably 5.0 or less, whereby the width of the particle size distribution becomes sharper and the flowability can be improved. On the other hand, (D 97 -D 10 ) / D 50 The lower limit of is, for example, 1.0 or more, preferably 1.1 or more, and more preferably 2.0 or more, whereby the particle size distribution has a certain width, and moldability can be improved.

[0024] D 97 / D 50 The upper limit of is, for example, 30.0 or less, preferably 20.0 or less, and more preferably 15.0 or less. This makes it possible to sharpen the particle size of the coarse particles, thereby preventing molding defects in the resin molding caused by the coarse particles. On the other hand, D 97 / D 50 The lower limit of is, for example, 2.0 or more, preferably 3.0 or more, and more preferably 5.0 or more, whereby the particle size distribution has a certain width, and fluidity and moldability can be improved.

[0025] The particle size distribution of spherical silica powder is a value based on particle size measurement using laser diffraction light scattering. Measurements can be performed using a particle size distribution analyzer, such as the Model LS-13-230 (manufactured by Beckman Coulter). For measurement, water is used as the solvent, and pretreatment involves dispersing the powder for 1 minute using a homogenizer at 200 W. The PIDS (Polarization Intensity Differential Scattering) concentration is adjusted to 45-55%. The refractive index of water is set to 1.33, while the refractive index of the powder is determined based on the refractive index of the powder material. For example, the refractive index of amorphous silica is set to 1.50.

[0026] A method for producing the spherical silica powder of this embodiment will be described.

[0027] Spherical silica powder, also known as molten spherical particles, is produced by supplying siliceous raw material powder into a high-temperature flame formed by the combustion reaction of a combustible gas and a combustion-supporting gas, and melting and spheroidizing it at a temperature above its melting point. If necessary, the molten spherical particles thus obtained may be classified or sieved.

[0028] An example of a schematic diagram of a thermal spraying device used to produce spherical silica powder is shown in FIG. The thermal spraying device 100 in FIG. 1 is composed of a melting furnace 2 equipped with a burner 1, cyclones 4 and 6 for classifying molten spherical particles generated by high-temperature exhaust gas from the flame by suction with a blower 9, and a bag filter 8 for collecting fine powder that could not be collected by the cyclones 4 and 6. The melting furnace 2 is constructed as a vertical furnace body, but is not limited to this, and may be a horizontal furnace or an inclined furnace that is horizontal and blows out flames horizontally. The hot exhaust gas is cooled by pipes 3, 5, and 7, which are equipped with water-cooled jackets. The blower 9 may be connected to a suction gas amount control valve and a gas exhaust port (not shown). A collected powder removal device (not shown) may be connected to the lower portions of the melting furnace 2, the cyclones 4 and 6, and the back filter 8. The classification can be carried out using known equipment such as a heavy settling chamber, a cyclone, a classifier having a rotor, etc. This classification operation may be carried out during the transportation process of the molten spheroidized product, or may be carried out in a separate line after collecting the molten spheroidized product all at once.

[0029] As the combustible gas, for example, one or more of acetylene, propane, butane, etc. may be used, but propane, butane, or a mixture thereof, which have a relatively small calorific value, are preferred. As the combustion supporting gas, for example, a gas containing oxygen is used. Generally, it is most preferable to use pure oxygen of 99% by weight or more, as it is inexpensive. In order to reduce the calorific value of the gas, an inert gas such as air or argon can be mixed with the combustion supporting gas.

[0030] The spherical silica powder may be either amorphous and / or crystalline.

[0031] The amorphous fraction of the spherical silica powder is preferably 95% or more, and more preferably 97% or more, as measured by the following method. The amorphous fraction is determined by X-ray diffraction analysis using a powder X-ray diffractometer (e.g., Rigaku Corporation, Model MiniFlex) in the 2θ range of 26° to 27.5° with CuKα radiation, and the intensity ratio of specific diffraction peaks is used to determine the amorphous fraction. In the case of siliceous powder, crystalline silica exhibits a main peak at 26.7°, while amorphous silica exhibits no peak. When amorphous and crystalline silica are mixed, a peak height at 26.7° corresponding to the proportion of crystalline silica is obtained. Therefore, the crystalline silica mixing ratio (X-ray diffraction intensity of sample / X-ray diffraction intensity of crystalline silica) is calculated from the ratio of the X-ray intensity of the sample to that of a crystalline silica standard sample, and the amorphous fraction is then calculated using the formula: amorphous fraction (%) = (1 - crystalline silica mixing ratio) × 100.

[0032] The spherical silica powder has a specific surface area S measured by the BET method. B and the theoretical specific surface area S calculated from the particle size distribution C Ratio to (S B / S C ) is preferably, for example, 2.5 or less. A large ratio means that the resin composition contains a large amount of ultrafine particles that cannot be detected by a particle size distribution measuring instrument such as a laser diffraction method. From the viewpoint of suppressing an increase in viscosity when the spherical silica particles are blended into the resin composition, the above S B / S C The value is more preferably 2.5 or less, and particularly preferably 2.0 or less.

[0033] Specific surface area S B is a value based on the BET method, and can be measured using, for example, a "Model 4-SORBU2" (manufactured by Yuasa Ionics Co., Ltd.) as a specific surface area measuring device. Theoretical specific surface area S C The particle size distribution can also be calculated automatically by the particle size distribution analyzer. The principle of this analyzer is as follows: C= 6 / (ρ·D), where D is the area-average particle diameter (μm) and ρ is the density of the spherical silica powder (g / cm 3 ) For example, if the powder is amorphous silica, it is 2.21. D can be calculated using the formula D=Σ(ni·ai·di) / Σ(ni·ai). This means that in a single powder mass, there are n1, n2, ni, and nk particles with diameters d1, d2, ···di, and ··dk, in order of smallest particle diameter, and if the surface areas per particle are a1, a2, ···ai, and ··ak, respectively, D can be calculated using the formula D=(n1·a1·d1+n2·a2·d2+···+ni·ai·di+···+nk·ak·dk) / (n1·a1·+n2·a2+···+ni·ai+···+nk·ak).

[0034] It is preferable that the spherical silica powder does not substantially contain particles smaller than 50 nm, which can prevent an increase in viscosity when blended into a resin composition. "Substantially free of particles smaller than 50 nm" means that the number of particles smaller than 50 nm in 100 random photographs taken at a magnification of 50,000 times using an electron microscope is counted, and the average value per photograph is calculated to be less than 50. The fewer particles smaller than 50 nm, the better.

[0035] Electron micrographs were taken using a field emission scanning electron microscope (JEOL model "FE-SEM, JSM-6301F") at an acceleration voltage of 15 kV and an irradiation current of 3 × 10-11 A. As a pretreatment for the photographs, carbon was evaporated onto the spherical silica powder for 2 seconds using a vacuum evaporation device (JEOL model "JEE-4X"), and then gold-palladium was evaporated for 60 seconds.

[0036] A resin composition containing the spherical silica powder of the present invention can be suitably used as a resin molding material.

[0037] Next, the resin composition of this embodiment will be described.

[0038] The resin composition contains, in addition to the spherical silica powder of the present invention, a resin and known resin additives.

[0039] The resin composition may contain spherical silica powder alone or in combination with other fillers. The resin composition may contain 10 to 99% by mass of spherical silica powder, or 10 to 99% by mass of a mixed inorganic powder containing spherical silica powder and other fillers. The content of the other fillers in the mixed inorganic powder may be, for example, 1 to 20% by mass or 3 to 15% by mass relative to 100% by mass of the spherical silica powder. In this specification, unless otherwise specified, the symbol "to" indicates that the upper and lower limits are included.

[0040] Examples of other fillers include alumina, titania, silicon nitride, aluminum nitride, silicon carbide, talc, calcium carbonate, etc. The average particle size of the other fillers is about 5 to 100 μm, and there are no particular restrictions on the particle size structure and shape.

[0041] Examples of the resin include epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyamide such as polyimide, polyamideimide, polyetherimide, polyester such as polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide-modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber-styrene) resin, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin, etc. These may be used alone or in combination of two or more.

[0042] The resin composition can be produced, for example, by blending raw material components in a predetermined ratio using a blender, a Henschel mixer, or the like, kneading the mixture using a heated roll, a kneader, a single-screw or twin-screw extruder, or the like, cooling the mixture, and then pulverizing it.

[0043] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0044] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0045] <Production of spherical silica powder> A burner 1 was installed above a melting furnace 2, and a collection line consisting of cyclones 4 and 6 and a bag filter 8 was directly connected below the burner 1. The thermal spraying apparatus 100 shown in FIG. 1 was used to produce spherical silica powder. Burner 1 has a double-pipe structure capable of forming an inner flame and an outer flame, and is installed at the top of melting furnace 2, to which combustible gas supply pipe 11, combustion supporting gas supply pipe 12, and raw material supply pipe 13 are connected. In the melting furnace 2, siliceous raw material powder is fed into a high-temperature flame through a raw material supply pipe 13 and melted to form molten spherical particles. The molten spherical particles that have passed through the melting furnace 2 are sucked in by a blower 9 together with the combustion exhaust gas, move by the air through pipes 3, 5, and 7, and are classified and collected in cyclones 4 and 6 or a bag filter 8.

[0046] (Examples 1 to 12, Comparative Examples 1 and 2) Using the above-mentioned thermal spraying device 100, LPG was supplied as a combustible gas from the combustible gas supply pipe 11, and oxygen was supplied as a combustion supporting gas from the combustion supporting gas supply pipe 12. A high-temperature flame was formed by combustion of the LPG and oxygen in the burner 1. A 20 Nm 3 / hr, burner flammable gas supply volume 8Nm 3 / hr, the supply of combustion support gas is 20Nm 3 / hr. Natural silica powder (average particle size 5 μm to 50 μm) was supplied to the flame formed as described above to obtain spherical amorphous silica powder. The obtained powder was classified and the classified powders were mixed to obtain powders of Examples 1 to 12.

[0047] (Comparative Examples 1 and 2) A spherical silica powder was obtained in the same manner as in the above example, except for the powder supply amount and the flame formation conditions. In Comparative Example 1, the powder supply amount was 2.0 times that of Example 1, and the carrier gas for the raw material was 20 Nm 3 / hr, burner flammable gas supply volume 5Nm 3 / hr, supply of combustion support gas of 15Nm 3 / hr. In Comparative Example 2, the powder supply amount was 3.3 times that of Example 1, and the carrier gas for the raw material was 15 Nm 3 / hr, burner flammable gas supply volume 4Nm 3 / hr, supply of combustion support gas of 15Nm 3 / hr.

[0048] [Table 1]

[0049] <Sphericity> The sphericity of the spherical silica powder was determined as follows under the conditions of a room temperature of 25°C and a humidity of 60%. The spherical silica powder thus obtained was measured using a wet flow image analyzer (FPIA-3000, manufactured by Sysmex Corporation) for the following sphericity: S1 for particle diameters of 5 μm or more and less than 10 μm, S2 for particle diameters of 10 μm or more and less than 20 μm, S3 for particle diameters of 20 μm or more and less than 30 μm, S4 for particle diameters of 30 μm or more and less than 45 μm, and S5 for particle diameters of 45 μm or more. [Measurement procedure] The measurement sample used in the above-mentioned wet flow type image analyzer was prepared as follows. 0.05 g of spherical silica powder sample was weighed into a 20 ml glass beaker, 10 ml of a 25% by mass propylene glycol aqueous solution was added, and the mixture was dispersed for 3 minutes using an ultrasonic disperser (ASU-10M manufactured by AS ONE Corporation). The entire amount was placed into the FPIA-3000 and measured using the LPF mode / quantitative counting method (total count of 100 particles, repeated measurement once). The perimeter of a single particle projected image and the perimeter of a circle corresponding to the area of ​​the particle projected image were analyzed using the above-mentioned wet flow type image analyzer, and the circularity was calculated using the following formula. Circularity = (perimeter of the projected particle image) / (perimeter of the circle equivalent to the area of ​​the projected particle image) The sphericity and circularity are average values ​​for particles within each particle size class. The sphericity was calculated as the square of the circularity of each particle size class. Also, S1, S 2 、 S3, S4, and S5 5 The average sphericity (S AVE ) was calculated.

[0050] <Loose bulk density, hard bulk density, compression degree> The loose bulk density, packed bulk density and compressibility of the spherical silica powder were determined under the conditions of room temperature of 25°C and humidity of 60% as follows. The obtained spherical silica powder was allowed to fall naturally from a height of 25 cm at a rate of 5 to 10 g per minute, and then dropped to a height of 100 cm. 3 A heaping cup was prepared by pouring the liquid into a measuring cup and continuing until it overflowed. Next, for the heaping cup, without tapping, the amount overflowing on the top of the cup was leveled off, and then the mass (g) of the spherical silica powder filled in the cup was measured, and the loose bulk density (g / cm 3 ) was calculated. On the other hand, for the heaping cup, after tapping it up and down 180 times (stroke length 2 cm, 1 second / time), the amount that overflowed onto the top of the cup was leveled off, and the mass (g) of the spherical silica powder filled in the cup was measured, and the compacted bulk density (g / cm 3 ) was calculated. When the loose bulk density obtained by the above procedure is A and the hardened bulk density is P, the compressibility (%) was calculated based on the formula: ((PA) / P)×100.

[0051] <Particle size distribution> The volume frequency particle size distribution of the obtained spherical silica powder was determined by a wet laser diffraction scattering method using a particle size distribution analyzer (Beckman Coulter, LS-13-230). Water was used as the solvent, and the powder was pre-dispersed for 1 minute using a homogenizer at 200 W output before measurement. The PIDS (Polarization Intensity Differential Scattering) concentration was adjusted to 45-55% before measurement. Based on the obtained volume frequency particle size distribution, the particle diameter D at which the cumulative value becomes X% X was calculated.

[0052] <Flowability of Resin Composition> 90 parts by mass of the obtained silica powder, 5.5 parts by mass of biphenyl-type epoxy resin (YX-4000HK manufactured by Japan Epoxy Resins Co., Ltd.), 4.8 parts by mass of phenolic resin (phenol aralkyl resin, MEHC-7800S manufactured by Meiwa Chemical Industry Co., Ltd.), 0.15 parts by mass of triphenylphosphine (TPP manufactured by Hokko Chemical Industry Co., Ltd.), and 0.35 parts by mass of N-phenyl-3-aminopropyltrimethoxysilane (KBM-573 manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed using a Henschel mixer (FM-20C / I manufactured by Nippon Coke and Engineering Co., Ltd.) at room temperature and a rotation speed of 2000 rpm. The resulting mixture was heated and kneaded in a co-rotating intermeshing twin-screw extruder kneader (screw diameter D = 25 mm, L / D = 10.2, paddle rotation speed 50 to 120 rpm, discharge rate 3.0 kg / Hr, kneaded product temperature 98 to 100°C) to obtain a resin composition. The obtained resin composition was used in a spiral flow mold in accordance with EMMI-1-66 (Epoxy Molding Material Institute; Society of Plastics Industry) at a mold temperature of 175°C, a molding pressure of 7.4 MPa, and a pressure dwell time of 90 seconds. A spiral flow of 120 cm or more was evaluated as good, and a spiral flow of less than 120 cm was evaluated as poor.

[0053] <Moldability of resin composition> Using the resin composition obtained in the evaluation of the above <Flowability of Resin Composition>, a mold with a resin thickness of 70 μm above and below the chip was used, and a transfer molding machine was used to produce a 48-pin TSOP encapsulating a simulated element, which was then visually inspected for any appearance defects such as unfilled areas. Those with no appearance defects were rated as good, and those with appearance defects were rated as bad. The mold temperature was 175°C, the molding pressure was 7.4 MPa, and the pressure holding time was 120 seconds. After molding, the mold was post-cured at 155°C for 6 hours.

[0054] The spherical silica powders of Examples 1 to 12 showed results that they could improve the fluidity compared to Comparative Example 1 and could improve the moldability compared to Comparative Example 2.

[0055] This application claims priority based on Japanese Patent Application No. 2022-018509, filed February 9, 2022, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0056] 1 burner 2. Melting furnace 3 Piping 4. Cyclone 5 Piping 6. Cyclone 7 Piping 8. Bag filter 9 Blower 11 Combustible gas supply pipe 12 Combustion auxiliary gas supply pipe 13 Raw material supply pipe 100 Thermal spraying equipment

Claims

1. The sphericity of the spherical silica powder having a particle diameter of 5 μm or more and less than 10 μm, as measured using a wet flow image analyzer, is defined as S １ The sphericity of particles with a diameter of 10 μm or more and less than 20 μm is S ２ The sphericity of particles with a diameter of 20 μm or more and less than 30 μm is S ３ The sphericity of particles with a diameter of 30 μm or more and less than 45 μm is S ４ The sphericity of particles with a diameter of 45 μm or more is S ５ When S １ , S ２ , S ３ , S ４ , and S ５ At least two of the above are 0.74 or more, The average sphericity calculated from the average values ​​of S 1 , S 2 , S 3 , S 4 , and S 5 (excluding the values ​​of 0) is defined as S AVE ; In the volume frequency particle size distribution of the spherical silica powder measured by a wet laser diffraction scattering method, the particle diameter at which the cumulative value reaches 50% is defined as D 50 (μm). A spherical silica powder configured such that S AVE and D 50 satisfy 0.01 / μm≦S AVE / D 50 ≦0.050 / μm.

2. The spherical silica powder according to claim 1, In the volume frequency particle size distribution measured by the wet laser diffraction scattering method, the particle diameter at which the cumulative value reaches 50% is defined as D ５０ (μm), and the particle diameter at which the cumulative value reaches 97% is D ９７ (μm), D ９７ / D ５０ is 2.0 or more and 30.0 or less.

3. The sphericity of the spherical silica powder having a particle diameter of 5 μm or more and less than 10 μm, as measured using a wet flow image analyzer, is defined as S １ The sphericity of particles with a diameter of 10 μm or more and less than 20 μm is S ２ The sphericity of particles with a diameter of 20 μm or more and less than 30 μm is S ３ The sphericity of particles with a diameter of 30 μm or more and less than 45 μm is S ４ The sphericity of particles with a diameter of 45 μm or more is S ５ When S １ , S ２ , S ３ , S ４ , and S ５ At least two of the above are 0.74 or more, In the volume frequency particle size distribution measured by a wet laser diffraction scattering method, when the particle diameter at which the cumulative value is 50% is D 50 (μm) and the particle diameter at which the cumulative value is 97% is D 97 (μm), A spherical silica powder having a D 97 / D 50 ratio of 5.0 or more and 30.0 or less.

4. The spherical silica powder according to claim 3, The average sphericity calculated from the average values ​​of S 1 , S 2 , S 3 , S 4 , and S 5 (excluding the values ​​of 0) is defined as S AVE ; In the volume frequency particle size distribution of the spherical silica powder measured by a wet laser diffraction scattering method, the particle diameter at which the cumulative value reaches 50% is defined as D 50 (μm). A spherical silica powder having S AVE and D 50 satisfying 0.01 / μm≦S AVE / D 50 ≦0.1 / μm.

5. The spherical silica powder according to any one of claims 1 to 4, S １ , S ２ , S ３ , S ４ , and S ５ The average sphericity calculated from the average of the five values ​​(excluding those with a value of 0) is S ＡＶＥ When this is done, S ＡＶＥ is 0.77 or more.

6. The spherical silica powder according to any one of claims 1 to 4, The compacted bulk density, measured by the following procedure B, is 1.2 g / cm ３ 1.6g / cm or more ３ The following is a spherical silica powder. (Procedure B) The spherical silica powder was allowed to fall naturally from a height of 25 cm at a rate of 5 to 10 g per minute, and then dropped to a height of 100 cm. ３ Prepare a heaping cup by pouring the contents into the measuring cup and continuing until it overflows. Next, for the heaping cup, the amount overflowing from the top of the cup was leveled off without tapping, and then the mass (g) of the spherical silica powder filled in the cup was measured, and the loose bulk density (g / cm ３ ) is calculated. On the other hand, the heaping cup was tapped up and down 180 times (stroke length 2 cm, 1 second / time), and then the overflowed portion on the top surface of the cup was leveled off. Then, the mass (g) of the spherical silica powder filled in the cup was measured, and the compacted bulk density (g / cm ３ ) is calculated.

7. The spherical silica powder according to claim 6, When the loose bulk density measured by the procedure B is A and the hard bulk density is P, A spherical silica powder having a compressibility of 15% or more and 50% or less, calculated based on ((P-A) / P) x 100.

8. The spherical silica powder according to any one of claims 1 to 4, In the volume frequency particle size distribution measured by the wet laser diffraction scattering method, the particle diameter at which the cumulative value reaches 10% is defined as D １０ (μm), and the particle diameter at which the cumulative value reaches 50% is D ５０ (μm), and the particle diameter at which the cumulative value reaches 97% is D ９７ (μm), (D ９７ -D １０ ) / D ５０ is 1.0 or more and 10.0 or less.

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