Inorganic powder

Abstract

This inorganic powder contains a spherical alumina powder and a spherical silica powder, and 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 inorganic powder using a wet-mode flow image analysis device, at least two values among S1, S3, S4, and S5 are 0.89 or higher, and S2 is 0.75 to less than 0.89.

Description

Technical Field

[0001] The present invention relates to inorganic powder.

Background Art

[0002] Various developments have been made on inorganic powder so far. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes spherical alumina powder having a silica coating layer, which is spheroidized by a flame spraying method, as the inorganic powder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as a result of the study by the present inventor, it has been found that when the inorganic powder described in Patent Document 1 is blended with a resin, there is room for improvement in terms of burr generation during molding and the mechanical strength of the molded body.

Means for Solving the Problems

[0005] As a result of further study by the present inventor, it has been found that in an inorganic powder containing spherical alumina powder and spherical silica powder, by appropriately controlling the sphericity, burr generation during molding can be suppressed in a resin composition in which this is blended with a resin, and the mechanical strength of the molded body can be improved, and the present invention has been completed.

[0006] According to one aspect of the present invention, the following inorganic powder is provided. 1. An inorganic powder containing spherical alumina powder and spherical silica powder, When the sphericity of the inorganic powder with a particle size of 5 μm or more and less than 10 μm is S1, the sphericity of the particle size of 10 μm or more and less than 20 μm is S2, the sphericity of the particle size of 20 μm or more and less than 30 μm is S3, the sphericity of the particle size of 30 μm or more and less than 45 μm is S4, and the sphericity of the particle size of 45 μm or more is S5, which are measured using a wet flow type image analyzer, At least two of S1, S3, S4, and S5 are 0.89 or more, and S2 is 0.75 or more and less than 0.89, Inorganic powder. 2. The inorganic powder according to 1., The average sphericity S obtained from the average value of four of S1, S3, S4, and S5 (excluding those with a value of 0) 3 , , 3 , , , , , 3 When it is set as, S AVE Is 0.89 or more, inorganic powder. 3. The inorganic powder according to 1. or 2., The average sphericity S obtained from the average value of four of S1, S3, S4, and S5 (excluding those with a value of 0) AVE Set as, When the median diameter measured using a wet flow type image analyzer is S 50 (μm), S AVE And S 50 Are configured to satisfy 0.20 ≦ (S AVE ) 2 / S 50 ≦ 0.50, inorganic powder. 4. The inorganic powder according to any one of 1. to 3., Under the conditions of room temperature 25 ° C and humidity 55%, the bulk density measured by the following procedure B is 1.5 g / cm 3 Or more and 2.3 g / cm 3 Or less, inorganic powder. (Procedure B) ​​​​Next, for the overflowing cup, without tapping, the amount that overflowed from the top of the cup was leveled off, and the mass (g) of the inorganic powder filled in the cup was measured, and the loose bulk density (g / cm³) was calculated. 3 Calculate ). On the other hand, for the overflowing cup, after tapping it 180 times in the vertical direction (stroke length 2 cm, 1 second / tap), and leveling off the excess powder on the top of the cup, the mass (g) of the inorganic powder filled in the cup was measured, and the bulk density (g / cm³) was determined. 3 Calculate ). 5. The inorganic powder described in 1. to 4., When the loose bulk density measured in procedure B above is A and the firm bulk density is P, An inorganic powder whose compression degree, calculated based on ((PA) / P)×100, is between 30% and 44%. 6. An inorganic powder as described in any one of items 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 The particle size at which the cumulative value reaches 50% is D 50 The particle size at which the cumulative value reaches 97% is D 97 In that case, (D 97 -D 10 ) / D 50 However, it is an inorganic powder with a value between 4 and 30. 7. An inorganic powder described in any one of items 1 to 6, 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 The particle size at which the cumulative value reaches 50% is D 50 , when that is the case, D 50 -D 10 However, it is an inorganic powder with a particle size of 0.5 μm or more and 17 μm or less. [Effects of the Invention]

[0007] According to the present invention, an inorganic powder is provided that, when incorporated into a resin, can suppress the generation of burrs during molding and improve the mechanical strength of the molded article. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing the configuration of a thermal spraying apparatus. [Modes for carrying out the invention]

[0009] The outline of the inorganic powder of this embodiment will be described below.

[0010] The inorganic powder of this embodiment includes spherical alumina powder and spherical silica powder, and is configured such that, when the sphericity of particles with a diameter of 5 μm or more and less than 10 μm is measured using a wet flow-type image analysis device, S1 is the sphericity of particles with a diameter of 10 μm or more and less than 20 μm is S2, the sphericity of particles with a diameter of 20 μm or more and less than 30 μm is S3, the sphericity of particles with a diameter of 30 μm or more and less than 45 μm is S4, and the sphericity of particles with a diameter of 45 μm or more is S5, at least two of S1, S3, S4, and S5 are 0.89 or higher, and S2 is 0.75 or higher and less than 0.89.

[0011] At least two of S1, S3, S4, and S5 are 0.89 or higher, preferably 0.91 or higher, and more preferably 0.92 or higher. This improves the fluidity, flexural strength, and burr characteristics of the resin composition.

[0012] Furthermore, at least two, preferably three, and more preferably four of S1, S3, S4, and S5 satisfy a value of 0.89 or higher. This improves the fluidity, flexural strength, and burr characteristics of the resin composition.

[0013] The lower limit of S2 is 0.75 or higher, preferably 0.81 or higher, and more preferably 0.83 or higher. This improves the bending strength. The upper limit of S2 is, for example, less than 0.89, preferably 0.87 or less, and more preferably 0.86 or less. This improves the bending strength.

[0014] The mean sphericity is calculated from the average values ​​of four values: S1, S3, S4, and S5 (excluding those with a value of 0). AVE The median diameter of the spherical silica powder is measured using a wet flow-type image analysis device, and S 50 Let it be (μm).

[0015] S AVE The lower limit is, for example, 0.89 or higher, preferably 0.90 or higher, and more preferably 0.91 or higher. This improves the fluidity of the resin composition. AVE The upper limit may be, for example, 0.99 or less.

[0016] S AVE and S 50 However, 0.20≦(S AVE ) 2 / S 50 It may be configured to satisfy ≤0.50. (S AVE ) 2 / S 50 The lower limit is, for example, 0.20 or higher, preferably 0.21 or higher, and more preferably 0.22 or higher. This improves the fluidity of the resin composition. (S AVE ) 2 / S 50 The upper limit is, for example, 0.50 or less, preferably 0.45 or less, and more preferably 0.40 or less. This improves the bending strength.

[0017] For inorganic powders, the degree of compression is calculated based on ((PA) / P) × 100, using the loose bulk density (A) and the hard bulk density (P) obtained by procedure B below.

[0018] The upper limit of the compressibility of the inorganic powder is, for example, 44% or less, preferably 43% or less, and more preferably 42% or less. This is expected to improve the miscibility of the inorganic powder with the resin. The lower limit of the compressibility of inorganic powders is, for example, 30% or more, preferably 31% or more, and more preferably 32% or more. This is expected to improve the handling properties of the powder.

[0019] The upper limit for the firm bulk density (P) of inorganic powders is, for example, 2.3 g / cm³. 3 Preferably 2.2 g / cm³ 3 More preferably, 2.1 g / cm³ 3 The following is the result: This increases density and has the potential to improve the strength of the resin composition. The lower limit of the bulk density (P) for inorganic powders is, for example, 1.5 g / cm³. 3 Preferably 1.6 g / cm³ 3 More preferably 1.7 g / cm³ 3 That concludes the explanation. This improves the handling of powders.

[0020] (Measurement procedure B for firm bulk density and loose bulk density) The inorganic powder is added at a rate of 5-10g per minute, allowed to fall naturally from a height of 25cm, and then 100cm 3 Pour the mixture into the measuring cup and continue until it overflows, preparing a heaping cup. Next, for the overflowing cup, without tapping, the amount that overflowed from the top of the cup was leveled off, and the mass (g) of the inorganic powder filled in the cup was measured, and the loose bulk density (g / cm³) was calculated. 3 Calculate ). On the other hand, for the overflowing cup, after tapping it 180 times in the vertical direction (stroke length 2 cm, 1 second / tap), and leveling off the excess powder on the top of the cup, the mass (g) of the inorganic powder filled in the cup was measured, and the bulk density (g / cm³) was determined. 3 Calculate ).

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

[0022] (D 97 -D10 ) / D 50 The lower limit is, for example, 4 or more, preferably 5 or more, more preferably 6 or more. If the particle size distribution becomes too narrow, D 50 If the size becomes too large, the fluidity and packing properties of the powder itself may deteriorate. (D 97 -D 10 ) / D 50 The upper limit is, for example, 30 or less, preferably 25 or less, more preferably 20 or less. If the particle size distribution is too broad, D 50 By keeping the size within an appropriate range without becoming too small, the fluidity and packing properties of the powder itself can be improved.

[0023] D 50 -D 10 The upper limit is, for example, 17 μm or less, preferably 16 μm or less, and more preferably 15 μm or less. This ensures appropriate fluidity, thermal conductivity, and other properties. D 50 -D 10 The lower limit is, for example, 0.5 μm or more, preferably 1 μm or more, and more preferably 2 μm or more. This ensures proper filling.

[0024] The particle size distribution of inorganic powders is a value based on particle size measurement by laser diffraction scattering, and can be measured using a particle size distribution analyzer such as the "Model LS-13230" (manufactured by Beckman Coulter). For measurement, water is used as the solvent, and as a pretreatment, the powder is dispersed using a homogenizer at a power of 200W for 1 minute. The PIDS (Polarization Intensity Differential Scattering) concentration is also prepared to be 45-55%. The refractive index of water is set to 1.33, and the refractive index of the powder material is taken into consideration. For example, amorphous silica is measured with a refractive index of 1.50, and alumina with a refractive index of 1.68.

[0025] In this embodiment, the sphericity, median diameter, bulk density, and compressibility can be controlled by appropriately selecting, for example, the types and amounts of each component contained in the inorganic powder, the method of preparing the inorganic powder, etc. Among these, for example, applying appropriate storage treatment to the alumina powder and / or silica powder immediately after collection, appropriately adjusting the opening degree during the classification treatment of these powders, and using spherical alumina powder and spherical silica powder of different particle sizes in combination are examples of factors that can bring the sphericity, median diameter, bulk density, and compressibility within a desired numerical range. For example, to control the sphericity in each particle size class, the following can be considered: (i) reducing the raw material supply increases sphericity, and increasing it decreases it; (ii) when the particle sizes of multiple raw materials are close to the average particle size, sphericity increases, and the further they deviate from this, the lower the sphericity; (iii) when the flame temperature is high, sphericity increases, and when it is low, sphericity decreases; (iv) when the temperature of the combustible gas is high, sphericity increases, and when it is low, sphericity decreases; (v) when the auxiliary gas is close to the theoretical ratio, sphericity increases, and the further it deviates from this, the lower the sphericity; and (vi) appropriately introducing a dispersed gas reduces adhesion and increases sphericity.

[0026] The inorganic powder of this embodiment will be described in detail.

[0027] The spherical alumina powder and spherical silica powder contained in the inorganic powder are also called molten spherical particles, respectively. They are produced by supplying the 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 them above their melting point. If necessary, the molten spherical particles obtained in this way may be subjected to classification and sieving. For example, by producing spherical alumina powder and spherical silica powder separately and mixing them, an inorganic powder can be obtained.

[0028] Figure 1 shows an example of a schematic diagram of a thermal spraying apparatus used to produce molten spherical particles. The thermal spraying apparatus 100 in Figure 1 consists of a melting furnace 2 equipped with a burner 1, a cyclone 4 for classifying molten spherical particles generated by the high-temperature exhaust gas of the flame using the suction of a blower 9, and a bag filter 8 for collecting fine particles that could not be captured by the cyclone 4. The melting furnace 2 is composed of a vertical furnace body, but is not limited to this; it may also be a horizontal furnace or inclined furnace, which is horizontal in which the flame is blown out horizontally. The high-temperature exhaust gas is cooled by pipes 3 and 5 equipped with water-cooling jackets. The blower 9 may be connected to a suction gas volume control valve (not shown) and a gas exhaust port. A collection and extraction device (not shown) may be connected to the bottom of the melting furnace 2, cyclone 4, and back filter 8. Classification can be carried out using known equipment such as heavy sedimentation chambers, cyclones, and classifiers with rotating blades. This classification operation may be incorporated into the transport process of the molten spheroidized product, or it may be carried out on a separate line after bulk collection.

[0029] As the flammable gas, one or more types such as acetylene, propane, and butane can be used, but propane, butane, or a mixture thereof with a relatively low calorific value is preferred. As a combustion-supporting gas, for example, a gas containing oxygen is used. Generally, using pure oxygen of 99% by mass or higher is the most inexpensive and preferable option. To reduce the calorific value of the gas, an inert gas such as air or argon can also be mixed with the combustion-supporting gas.

[0030] As the raw material powder, alumina powder with an average particle size of 3 to 70 μm may be used. The aluminum hydroxide powder may be supplied into the high-temperature flame either dry or wet by slurring it with water or the like.

[0031] As the raw material powder, silica raw material powder may be used, for example, siliceous raw materials such as quartz or natural silica, adjusted to a particle size composition in which 15-50% of the particles are 1 μm or smaller and 50-80% are 5 μm or larger.

[0032] The content of spherical silica powder in the inorganic powder is, for example, 3 to 30% by mass, preferably 3 to 20% by mass, and more preferably 3 to 10% by mass, out of 100% by mass of the total value of spherical alumina powder and spherical silica powder.

[0033] The spherical silica powder may be amorphous and / or crystalline.

[0034] The spherical silica powder preferably has an amorphous content of 95% or more, and more preferably 97% or more, as measured by the following method. The amorphous content is measured using a powder X-ray diffractometer (e.g., RIGAKU's "Model MiniFlex"), performing X-ray diffraction analysis in the range of 26° to 27.5° for CuKα rays, and is determined from the intensity ratio of specific diffraction peaks. In the case of siliceous powder, crystalline silica has a main peak at 26.7°, but amorphous silica does not have a peak. When amorphous silica and crystalline silica are mixed, a peak height of 26.7° corresponding to the proportion of crystalline silica is obtained. The crystalline silica mixing ratio (X-ray diffraction intensity of the sample / X-ray diffraction intensity of crystalline silica) is calculated from the ratio of the X-ray intensity of the sample to the X-ray intensity of a crystalline silica standard sample, and the amorphous content is determined from the formula, Amorphous Content (%) = (1 - Crystalline Silica Mixing Ratio) × 100.

[0035] The inorganic powder of the present invention, when incorporated into a resin composition, can be suitably used as a resin molding material.

[0036] Next, the resin composition of this embodiment will be described.

[0037] The resin composition includes, in addition to the inorganic powder of the present invention, a resin and known resin additives. In the resin composition, the inorganic powder may be used alone or mixed with other fillers. The resin composition may contain 10 to 99% by mass of inorganic powder, or 10 to 99% by mass of mixed inorganic powder containing inorganic powder and other fillers. Furthermore, the content of 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 inorganic powder. In this specification, unless otherwise specified, "~" indicates that it includes both the upper and lower limits. Other fillers include, for example, titania, silicon nitride, aluminum nitride, silicon carbide, talc, and calcium carbonate. The average particle size of these other fillers is typically around 5 to 100 μm, and there are no particular restrictions on their particle size composition or shape.

[0038] Examples of the above-mentioned resins include epoxy resins, silicone resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters, fluororesins, polyimides, polyamide-imides, polyetherimides and other polyamides, polyesters such as polybutylene terephthalate and polyethylene terephthalate, polyphenylene sulfide, fully aromatic polyesters, polysulfones, liquid crystal polymers, polyethersulfones, polycarbonates, maleimide-modified resins, ABS resins, AAS (acrylonitrile-acrylic rubber-styrene) resins, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins. These may be used individually or in combination of two or more types.

[0039] Resin compositions can be manufactured, for example, by blending raw material components in predetermined ratios using a blender or Henschel mixer, then kneading them using a heated roll, kneader, single-screw or twin-screw extruder, cooling, and then grinding the mixture.

[0040] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0041] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to the descriptions of these examples.

[0042] <Manufacturing of inorganic powders> Using the thermal spraying apparatus 100 shown in Figure 1, various spherical alumina powders and spherical silica powders were produced. The thermal spraying apparatus 100 shown in Figure 1 comprises a melting furnace 2, a burner 1 installed on top of the melting furnace 2, and a collection system line consisting of a cyclone 4 and a bag filter 8 installed directly connected to the bottom of the melting furnace 2. Burner 1 has a double-tube structure capable of forming an inner flame and an outer flame, and is installed at the top of the melting furnace 2, to which the combustible gas supply pipe 11, the auxiliary combustion gas supply pipe 12, and the raw material supply pipe 13 are connected. In the melting furnace 2, raw material powder is supplied into a high-temperature flame from the raw material supply pipe 13 and melted to form spherical molten spherical particles. The molten spherical particles that have passed through the melting furnace 2 are sucked in by the blower 9 along with the combustion exhaust gas, move through the pipes 3 and 5 by air, and are classified and collected by the cyclone 4 or bag filter 8.

[0043] (Example 1) • Manufacturing of spherical alumina powder Using the thermal spraying apparatus 100 described above, LPG was supplied as a combustible gas from the combustible gas supply pipe 11, and atmospheric air was supplied as a combustion aid gas from the combustion aid gas supply pipe 12. A high-temperature flame was formed in the burner 1 by the combustion of LPG and oxygen. Secondary air is supplied to cyclone 4 by a rotary valve (not shown) installed in piping 3. Atmospheric air was used as the secondary air. The degree of opening / closing of the lower valve in cyclone 4 (lower opening) was set to 100%. As raw material powder, average particle size (D 50 Alumina powder having a maximum value in the range of 2 to 45 μm was used. Molten spherical particles collected by the bag filter 8 were recovered as spherical alumina powder. • Manufacturing of spherical silica powder As raw material powder, average particle size (D 50 ) uses 5μm natural silica powder, and 10Nm as the carrier gas for the raw materials. 3 / hr, the burner's flammable gas supply rate is 10 Nm³ 3 / hr, supply amount of auxiliary gas 25Nm 3 The process was the same as described above for the production of spherical alumina powder, except that the value was set to / hr. The molten spherical particles collected by the bag filter 8 are processed by determining the average particle size (D 50 ) was recovered as 0.3 μm spherical silica powder.

[0044] • Manufacturing of inorganic powders The spherical silica powder was stored in an aluminum bag (manufactured by Seisan Nippon Co., Ltd., Lamizip AL) at a humidity of 60-80% and a temperature of 20-30°C for 28 days immediately after collection (storage treatment). The spherical silica powder removed immediately after opening the aluminum bag and the spherical alumina powder produced as described above were mixed in a mass ratio of 90:10 to obtain inorganic powder.

[0045] (Examples 2-4) In the production of spherical alumina powder, an inorganic powder was obtained using spherical alumina powder obtained in the same manner as in Example 1 above, except that the lower opening was changed to 20%, 25%, and 35% during the classification process.

[0046] (Comparative Example 1) The spherical alumina powder described above was used as an inorganic powder without mixing it with spherical silica powder.

[0047] (Comparative Example 2) In the production of spherical alumina powder, inorganic powder was obtained in the same manner as in Example 1, except that the supply amount of combustible gas and auxiliary gas to the burner was 1.5 times that of Example 1, and the spherical silica powder that had been stored in the atmosphere for 28 days without the above-mentioned storage treatment was used.

[0048] [Table 1]

[0049] <Sphericity> The sphericity of the obtained inorganic powder was determined under conditions of room temperature (25°C) and humidity (70%) as follows. The obtained inorganic powder was analyzed using a wet flow image analyzer (Sysmex Corporation, FPIA-3000) to measure the sphericity of particles with diameters of 5 μm or more and less than 10 μm (S1), 10 μm or more and less than 20 μm (S2), 20 μm or more and less than 30 μm (S3), 30 μm or more and less than 45 μm (S4), and 45 μm or more (S5). Similarly, the median diameter (S) was measured. 50 ) was measured. [Measurement Procedure] The measurement samples used in the wet flow image analysis system described above were prepared as follows. 0.05 g of the inorganic powder sample is weighed into a 20 ml glass beaker, 10 ml of 25% by mass aqueous solution of propylene glycol is added, and the mixture is dispersed for 3 minutes using an ultrasonic disperser (AS ONE ASU-10M). The entire volume is then placed into the FPIA-3000 and measured using the LPF mode / quantitative count method (total count of 100 units, number of repeated measurements: 1). Using the wet flow-type image analysis system described above, the perimeter of a single particle projection image and the perimeter of a circle corresponding to the area of ​​the particle projection image were analyzed, and the circularity was determined using the following formula. Circularity = (Perimeter of the particle projection image) / (Perimeter of the circle corresponding to the area of ​​the particle projection image) Sphericity and circularity are the average values ​​for particles within each particle size class. Sphericity was defined as the square of the circularity of each particle size class. Additionally, the mean sphericity (S) is calculated from the average of the four values ​​S1, S3, S4, and S5 (excluding those with a value of 0). AVE ) was calculated.

[0050] <Loose bulk density, firm bulk density> The obtained inorganic powder was subjected to measurements of loose and hard bulk density using a powder tester (Hosokawa Micron Corporation, PT-E type) under conditions of room temperature (25°C) and humidity (55%). The specific steps are as follows: The inorganic powder, which is the measurement sample, is dropped naturally from a height of 25 cm at a rate of 5-10 g per minute, and then measured at 100 cm. 3 I poured it into the measuring cup and continued until it overflowed, preparing a heaping cup. Next, for the overflowing cup, without tapping, the amount that overflowed from the top of the cup was leveled off, and the mass (g) of the inorganic powder filled in the cup was measured, and the loose bulk density (g / cm³) was calculated. 3 ) was calculated. On the other hand, for the overflowing cup, after tapping it 180 times in the vertical direction (stroke length 2 cm, 1 second / tap), and leveling off the excess powder on the top of the cup, the mass (g) of the inorganic powder filled in the cup was measured, and the bulk density (g / cm³) was determined. 3 ) was calculated. When the loose bulk density obtained using the above procedure is denoted as A and the stiff bulk density as P, the degree of compressibility (%) was calculated based on the formula: ((PA) / P) × 100.

[0051] <Particle size distribution> The obtained inorganic powder was analyzed using a wet laser diffraction scattering method to determine its volume frequency particle size distribution. Water was used as the solvent, and as a pretreatment, the powder was dispersed using a homogenizer at 200W for 1 minute. The PIDS (Polarization Intensity Differential Scattering) concentration was adjusted to 45-55% for the measurement. Based on the obtained volume frequency particle size distribution, the particle size D at which the cumulative value is X% X The result was calculated.

[0052] <Bending strength> 90 parts by mass of the obtained inorganic powder, 5.5 parts by mass of biphenyl-type epoxy resin (YX-4000HK, manufactured by Japan Epoxy Resin Co., Ltd.), 4.8 parts by mass of phenol resin (phenol aralkyl resin, MEHC-7800S, manufactured by Meiwa Kasei 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 Industries Co., Ltd.) at room temperature and a rotation speed of 2000 rpm. The resulting mixture was heated and kneaded in a twin-screw extruder with co-direction meshing (screw diameter D=25 mm, L / D=10.2, paddle rotation speed 50~120 rpm, discharge rate 3.0 kg / Hr, kneaded material temperature 98~100°C) to obtain a resin composition.

[0053] The obtained resin composition was molded to a size of 4 mm × 16 mm × 80 mm at a mold temperature of 180°C, cured at 180°C for 6 hours, and then measured according to the bending strength (MPa) measurement method of JIS K 6911. Mechanical strength was evaluated as good if the bending strength was 135 MPa or higher, and as poor if it was less than 135 MPa.

[0054] <Variable Characteristics> Furthermore, the obtained resin composition was molded using a burr measuring mold with slits of 2 μm, 5 μm, 10 μm, and 30 μm. The molding temperature was 175°C and the molding pressure was 7.4 MPa. The resin that flowed out of the slits was measured with calipers, and the values ​​measured in each slit were averaged to determine the burr length (μm). If the burr length was 1 mm or less, it was evaluated as good (successful) as it could suppress burr generation during molding; if it exceeded 1 mm, it was evaluated as poor (there is a risk of burr generation during molding).

[0055] The inorganic powders of Examples 1 to 4 showed improved mechanical strength in molded articles of resin compositions compared to Comparative Examples 1 and 2, and suppressed burr formation during molding compared to Comparative Example 1.

[0056] This application claims priority based on Japanese Patent Application No. 2022-018511, filed on 9 February 2022, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0057] 1 burner 2. Melting furnace 3 Piping 4 Cyclone 5 Piping 8. Bug 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. An inorganic powder consisting of spherical alumina powder and spherical silica powder, The sphericity of the inorganic powder, measured using a wet flow image analysis system, for particles with a diameter of 5 μm or more and less than 10 μm, is defined as S. １ Sphericity of particles with a diameter of 10 μm or more and less than 20 μm ２ Sphericity of particles with a diameter of 20 μm or more and less than 30 μm ３ Sphericity of particles with a diameter of 30 μm or more and less than 45 μm ４ , the sphericity of particles with a diameter of 45 μm or more is S ５ In that case, S １ 、 S ３ 、 S ４ 、 and S ５ at least two or more of are 0.89 or more, and S ２ However, it is between 0.75 and 0.

89. Inorganic powder.

2. The inorganic powder according to claim 1, S １ S ３ S ４ , and S ５ The mean sphericity is calculated from the average of these four values ​​(excluding those with a value of 0) as S ＡＶＥ When S ＡＶＥ However, it is an inorganic powder with a value of 0.89 or higher.

3. The inorganic powder according to claim 1 or 2, S １ S ３ S ４ , and S ５ The mean sphericity is calculated from the average of these four values ​​(excluding those with a value of 0) as S ＡＶＥ year, The median diameter is measured using a wet flow-type image analysis system, and is defined as S. ５０ When (μm), S ＡＶＥ and S ５０ However, 0.20 ≤ (S ＡＶＥ ) 2 / S ５０ An inorganic powder configured to satisfy ≤0.

50.

4. The inorganic powder according to claim 1 or 2, Under conditions of room temperature of 25°C and humidity of 55%, the bulk density measured by procedure B below is 1.5 g / cm³. ３ 2.3g / cm or more ３ The following are inorganic powders. (Procedure B) The inorganic powder is added at a rate of 5 to 10 g per minute, allowed to fall naturally from a height of 25 cm, and then 100 cm ３ Pour the mixture into the measuring cup and continue until it overflows, preparing a heaping cup. Next, for the overflowing cups, without tapping, the amount that overflowed from the top of the cup was leveled off, and the mass (g) of the inorganic powder filled in the cup was measured, and the loose bulk density (g / cm³) was determined. ３ Calculate the result. On the other hand, for the overflowing cup, after tapping it 180 times in the vertical direction (stroke length 2 cm, 1 second / tap), and leveling off the excess powder on the top of the cup, the mass (g) of the inorganic powder filled in the cup was measured, and the bulk density (g / cm³) was determined. ３ Calculate the result.

5. The inorganic powder according to claim 4, When the loose bulk density measured in procedure B above is A and the firm bulk density is P, An inorganic powder whose degree of compression, calculated based on ((P - A) / P) × 100, is between 30% and 44%.

6. The inorganic powder according to claim 1 or 2, 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 The particle size at which the cumulative value reaches 50% is D ５０ The particle size at which the cumulative value reaches 97% is D ９７ In that case, (D ９７ -D １０ ) / D ５０ However, it is an inorganic powder with a value between 4 and 30.

7. The inorganic powder according to claim 1 or 2, 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 The particle size at which the cumulative value reaches 50% is D ５０ , when that is the case, D ５０ -D １０ However, it is an inorganic powder with a particle size of 0.5 μm or more and 17 μm or less.

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