Inorganic powder, filler for resin, resin composition, and method for producing inorganic powder

Abstract

Provided are: an inorganic powder which can achieve excellent fluidity when blended into a resin; a filler for a resin, which contains the inorganic powder; a resin composition which contains the inorganic powder; and a method for producing the inorganic powder. An inorganic powder having a Hausner ratio of 1.00 to 1.33 is provided. The resin composition contains the inorganic powder and at least one resin selected from the group consisting of thermoplastic resins and thermosetting resins. A method for producing an inorganic powder, the method comprising: dispersing a raw material powder in a liquid containing cavitation bubbles; and recovering the raw material powder from the liquid, and drying the recovered raw material powder.

Description

Technical Field

[0001] The present invention relates to an inorganic powder, a filler for resins, a resin composition, and a method for producing an inorganic powder. Background Art

[0002] Powders of inorganic metal compounds such as silica, alumina, and boron nitride exhibit their heat conductivity, insulating properties, etc., and are widely used as inorganic fillers for resins. Generally, when an inorganic filler is incorporated into a resin, there is a tendency for the fluidity of the resin composition to decrease.

[0003] As a resin composition containing an inorganic filler with excellent fluidity, for example, inorganic powders for adding to a resin composition having a specific particle size distribution and average circularity are proposed in Patent Documents 1 to 2.

[0004] Prior Art

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-248007

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2008-248004 Summary of the Invention

[0007] However, the fluidity improvement of conventional inorganic powders when filled in resins is insufficient.

[0008] Therefore, an object of the present invention is to provide an inorganic powder that can achieve excellent fluidity when incorporated into a resin, a filler for resins containing the above inorganic powder, a resin composition containing the above inorganic powder, and a method for producing the above inorganic powder.

[0009] The present inventors conducted intensive studies and found that as long as the inorganic powder has a Hausner ratio defined as the ratio of the tapped density to the bulk density within a certain range, the above technical problems can be solved, and thus the present invention was completed.

[0010] That is, the present invention has the following aspects.

[0011] [1] An inorganic powder having a Hausner ratio of 1.00 to 1.33.

[0012] [2] The inorganic powder according to [1], wherein the average particle diameter (D50) is 30 μm or less.

[0013] [3] The inorganic powder according to [1] or [2], having a specific surface area of 0.3 m 2 / g or more.

[0014] [4] The inorganic powder according to any one of [1]-[3] contains at least one selected from alumina powder, aluminum nitride powder, silica powder, silicon nitride powder, magnesium oxide powder, titanium oxide powder, zirconium oxide powder, zinc oxide powder, aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder.

[0015] [5] The inorganic powder according to any one of [1]-[4] is at least one selected from aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder.

[0016] [6] For the inorganic powder according to [5], the semi-quantitative value calculated from the peak intensity of O 1s measured by X-ray photoelectron spectroscopy is 0.6 or more.

[0017] [7] The inorganic powder according to any one of [1]-[6] is used for resin filling.

[0018] [8] A filler for resin contains the inorganic powder according to any one of [1]-[7].

[0019] [9] A resin composition contains the inorganic powder according to any one of [1]-[8] and at least one resin selected from thermoplastic resins and thermosetting resins.

[0020]

[10] A method for manufacturing an inorganic powder selected from any one of [1]-[7] includes: dispersing raw material powder in a liquid containing cavitation bubbles; and recovering the raw material powder from the liquid and then drying it.

[0021]

[11] For the manufacturing method according to

[10] , the above-mentioned dispersion includes using the cavitation bubbles to disperse the aggregated particles in the raw material powder.

[0022] According to the present invention, it is possible to provide an inorganic powder that can achieve excellent fluidity when compounded with a resin, a filler for resin containing the above inorganic powder, a resin composition containing the above inorganic powder, and a manufacturing method of the above inorganic powder. Detailed Embodiments

[0023] Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the range that does not affect the effects of the present invention. When the specific description of one embodiment is also applicable to other embodiments, the description may be omitted in other embodiments. In the present invention, the expression "X to Y" for a numerical range means "X or more and Y or less".

[0024] Each component and their combinations in each embodiment are an example. Without departing from the gist of the present invention, additions, omissions, substitutions, and other changes to the configuration can be appropriately made. The present invention is not limited by the embodiments. Each embodiment disclosed in this specification can be combined with any other features disclosed in this specification.

[0025] In addition, the "inorganic powder" in the present invention refers to a powder of an inorganic metal compound. In addition, "powder" refers to an aggregate of particles.

[0026] [Inorganic powder]

[0027] The Hausner ratio of the inorganic powder in this embodiment is 1.00 to 1.33. The "Hausner ratio" is the ratio of the tapped density to the bulk density and is represented by "(tapped density (g / cm 3 )) / bulk density (g / cm 3 ))". By setting the Hausner ratio to 1.00 to 1.33, the inorganic powder in this embodiment can provide a resin composition with excellent fluidity when filled in a resin. In addition, the tapped density and bulk density used to calculate the Hausner ratio can be measured by the following method.

[0028] (Method for measuring tapped density and bulk density)

[0029] First, dry the inorganic powder at 120°C for 5 hours. Then, weigh 5.00 ± 0.02 g (M1) of the dried inorganic powder using an analytical balance (an analytical balance with a minimum weighing value of 0.001 g) and put it into a 50 mL graduated cylinder. After putting it in, visually measure the volume (V1) of the inorganic powder in the graduated cylinder (to the first decimal place). Next, lift the graduated cylinder and let it fall 500 times from a height of 3.5 cm. At this time, let the graduated cylinder fall onto a rubber mat (thickness 40 mm) in such a way that the impact applied to the graduated cylinder is the same each time. After falling 500 times, visually measure the volume (V2) of the inorganic powder in the graduated cylinder (to the first decimal place). According to the following formulas (1) to (2), calculate the bulk density and tapped density of the inorganic powder. The bulk density and tapped density are calculated to two decimal places by rounding the third decimal place. In addition, the bulk density and tapped density are calculated in "g / cm 3 " with a 1 mL graduated cylinder regarded as 1 cm 3 ". In addition, the above measurement of the tapped density and bulk density is carried out under the conditions of a temperature of 21°C to 25°C and a humidity of 50% ± 4%.

[0030] Bulk density (g / cm 3 ): Mass (M1) of the inorganic powder / V1 ··· (1)

[0031] Tapped density (g / cm3 ):Mass (M1) of the inorganic powder / V2 ··· (2)

[0032] As described above, the Hausner ratio of the inorganic powder of the present embodiment is 1.00 to 1.33. In one embodiment, the preferred range of the Hausner ratio of the inorganic powder can be 1.00 to 1.11, can be 1.12 to 1.18, can be 1.19 to 1.25, and can be 1.26 to 1.33.

[0033] In addition, although it also depends on the type of the inorganic powder, etc., generally when the tapped density is low, the Hausner ratio becomes larger and is likely to exceed 1.33. That is, the volume of the inorganic powder with a small tapped density becomes larger and the bulk density also becomes smaller, so it is easy to form a powder with a Hausner ratio exceeding 1.33. Even if the tapped density of the inorganic powder of the present embodiment is low, the Hausner ratio can be in the range of 1.00 to 1.33. In one embodiment, the tapped density of the inorganic powder can be, for example, 2.30 g / cm 3 Hereinafter, it can be 2.00 g / cm 3 Hereinafter, it can be 1.70 g / cm 3 Hereinafter, it can be 1.50 g / cm 3 Hereinafter, it can be 1.30 g / cm 3 Hereinafter, or it can be 1.00 g / cm 3 Hereinafter. Even with such a tapped density, the Hausner ratio is likely to be in the above range, so it is easy to improve the fluidity. The lower limit of the tapped density of the inorganic powder is not particularly limited. For example, it can be 0.10 g / cm 3 or more, can be 0.20 g / cm 3 or more, can be 0.30 g / cm 3 or more. The tapped density of the inorganic powder of the present embodiment can adopt a range in which the above-mentioned preferred upper and lower limits are arbitrarily combined within the range where the Hausner ratio is 1.00 to 1.33.

[0034] In addition, although it also depends on the type of the inorganic powder, etc., as described above, generally when the bulk density is low, the Hausner ratio becomes larger and is likely to exceed 1.33. Even if the bulk density of the inorganic powder of the present embodiment is low, the Hausner ratio can be in the range of 1.00 to 1.33. In one embodiment, the bulk density of the inorganic powder can be 1.60 g / cm 3 or less, can be 1.40 g / cm 3 or less, can be 1.20 g / cm 3 or less, can be 1.00 g / cm 3 or less, or can be 0.80 g / cm 3Hereinafter. Even with such a bulk density, the Hausner ratio is liable to be within the above range, and thus the fluidity is liable to be improved. The lower limit of the bulk density of the inorganic powder is not particularly limited, and may be, for example, 0.05 g / cm 3 or more, may be 0.10 g / cm 3 or more, may be 0.20 g / cm 3 or more. The bulk density of the inorganic powder of the present embodiment may be in a range in which any combination of the above-described preferred upper and lower limits is used within a Hausner ratio of 1.00 to 1.33. The tapped density of the inorganic powder of the present embodiment is particularly preferably 1.00 g / cm 3 or less and the bulk density is 1.00 g / cm 3 or less.

[0035] Thus, an inorganic powder having a small difference between the tapped density and the bulk density can be prepared, for example, by a production method including dispersing a raw material powder of the inorganic powder in a liquid containing cavitation bubbles and then recovering and drying the powder. The production method of the inorganic powder will be described later. The production method of the inorganic powder of the present embodiment is particularly preferably applicable to an inorganic powder having a tapped density of 1.00 g / cm 3 or less and a bulk density of 1.00 g / cm 3 or less.

[0036] <Average particle diameter (D50)>

[0037] The average particle diameter (D50) of the inorganic powder of the present embodiment is preferably 30 μm or less. The average particle diameter (D50) of the inorganic powder refers to the volume-based cumulative diameter (D50) evaluated by the laser diffraction scattering method after performing a specific dispersion treatment, such as a homogenizer treatment. In addition, the "volume-based cumulative diameter (D50)" refers to the particle diameter at which the cumulative value corresponds to 50% in the volume-based cumulative particle size distribution measured by the laser diffraction scattering method. The cumulative particle size distribution is represented by a distribution curve having the particle diameter (μm) on the horizontal axis and the cumulative value (%) on the vertical axis.

[0038] Generally, when the average particle size (D50) of the inorganic powder (hereinafter sometimes referred to as "D50") is small, the Hausner ratio is likely to exceed the range of this embodiment. However, according to this embodiment, even if D50 is small, the Hausner ratio is likely to be in the range of 1.00 to 1.33. Therefore, even if D50 is 30 μm or less, the fluidity is likely to be improved. In one embodiment, the D50 of the inorganic powder can be 30 μm or less, can be 27 μm or less, can be 25 μm or less, can be 22 μm or less, can be 20 μm or less, can be 17 μm or less, can be 15 μm or less, can be 12 μm or less, or can be 9 μm or less. Even if D50 is below the above upper limit, the Hausner ratio is likely to be in the range of 1.00 to 1.33, so it is likely to be an inorganic powder with excellent fluidity. The lower limit of D50 of the inorganic powder is not particularly limited. For example, it can be 0.05 μm or more, can be 0.08 μm or more, can be 0.12 μm or more, can be 0.15 μm or more, can be 0.17 μm or more, can be 0.20 μm or more, can be 0.22 μm or more, or can be 0.25 μm or more. The D50 of the inorganic powder of this embodiment can adopt a range obtained by arbitrarily combining the above-preferred upper and lower limits within the range where the Hausner ratio is 1.00 to 1.33.

[0039] <Specific surface area>

[0040] Generally, when the specific surface area of the inorganic powder is large, the Hausner ratio is likely to exceed the range of this embodiment. However, according to this embodiment, even if the specific surface area is large, the Hausner ratio is likely to be in the range of 1.00 to 1.33. Therefore, even if the specific surface area is large, the fluidity is likely to be improved. In one embodiment, the specific surface area of the inorganic powder can be 0.1 m 2 / g or more, can be 0.2 m 2 / g or more, can be 0.3 m 2 / g or more, can be 0.4 m 2 / g or more, can be 0.5 m 2 / g or more, can be 0.6 m 2 / g or more, can be 0.7 m 2 / g or more, can be 0.8 m 2 / g or more, can be 0.9 m 2 / g or more, or can be 1.0 m 2 / g or more. Even if the specific surface area is above the above lower limit, it is likely to be an inorganic powder with excellent fluidity. The upper limit of the specific surface area of the inorganic powder is not particularly limited. For example, it can be 35 m 2 / g or less, can be 32 m 2 / g or less, can be 30 m 2less than / g, and can be 27 m 2 less than / g, and can be 25 m 2 less than / g, and can be 22 m 2 less than / g, and can be 20 m 2 less than / g, and can be 17 m 2 less than / g, or can be 15 m 2 less than / g. The specific surface area of the inorganic powder of this embodiment can be in the range of arbitrarily combining the above-mentioned preferred upper and lower limits within the range of Hausner ratio of 1.00 to 1.33.

[0041] In addition, in the present invention, the specific surface area of the inorganic powder can be measured by the BET multipoint method using nitrogen in accordance with JIS Z8830:2013.

[0042] The inorganic powder of this embodiment preferably contains at least one selected from alumina powder, aluminum nitride powder, silica powder, silicon nitride powder, magnesium oxide powder, titanium oxide powder, zirconium oxide powder, zinc oxide powder, aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder, more preferably contains at least one selected from alumina powder, aluminum nitride powder, silica powder, silicon nitride powder, aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder, and further preferably contains at least one selected from alumina powder, silica powder, aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder. In one embodiment, the inorganic powder may contain one of the above powders alone, or may be a mixed powder containing two or more kinds. In addition, when the inorganic powder is a mixed powder, the mixing ratio of each powder can be arbitrarily set.

[0043] The shapes of alumina powder, aluminum nitride powder, silica powder, silicon nitride powder, magnesium oxide powder, titanium oxide powder, zirconium oxide powder, and zinc oxide powder are not particularly limited, and can be spherical or amorphous. From the viewpoints of fluidity during filling and viscosity reduction, spherical shape is preferred.

[0044] In one embodiment, the inorganic powder is preferably at least one powder selected from aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder, and more preferably flaky boron nitride powder or spherical boron nitride powder.

[0045] Boron nitride powder has lubricity, high thermal conductivity, and insulation, and is widely used in solid lubricants, mold release agents for molten gas, aluminum, and the like, and fillers for heat dissipation materials. If the inorganic powder of this embodiment is at least one powder selected from the above-mentioned agglomerated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder, it is easy to provide a solid lubricant, a mold release agent, and a filler for heat dissipation materials that have better fluidity than before. In the present invention, "agglomerated boron nitride powder" refers to a powder in which primary particles of hexagonal boron nitride in the form of flakes are aggregated to form a block.

[0046] In the present invention, "spherical powder" refers to a powder that is round or has rounded particles when the powder is observed using a scanning electron microscope at a magnification of 10,000 times. In one embodiment, the average circularity of the spherical boron nitride powder may be greater than 0.70, greater than 0.75, greater than 0.80, or greater than 0.87. In addition, the "average circularity" may be calculated by the following method.

[0047] (Method for measuring average circularity)

[0048] The image of the powder taken using a scanning electron microscope (SEM) (magnification: 10,000 times, image resolution: 1280×1024 pixels) is analyzed by using image analysis software (e.g., manufactured by Mountech, trade name: MacView) to calculate the projected area (S) and perimeter (L) of one particle. The projected area (S) and perimeter (L) are substituted into the following formula (3) to obtain the circularity. The average circularity obtained for any 200 particles is taken as the average circularity.

[0049] Circularity = 4πS / L 2 …(3)

[0050] In one embodiment, the inorganic powder has an O content determined by X-ray photoelectron spectroscopy. 1s The semi-quantitative value calculated from the peak intensity (hereinafter sometimes referred to as “ 1s The semi-quantitative value (“semi-quantitative value”) is preferably 0.6 or more, more preferably 0.65 or more, and further preferably 0.7 or more. In the present invention, “the O measured by X-ray photoelectron spectroscopy” 1s The "semi-quantitative value calculated from the peak intensity" means that the spectrum obtained by measuring the inorganic powder using an X-ray photoelectron spectrometer (for example, manufactured by Thermo Fischer, product name: K-Alpha type X-ray photoelectron spectrometer, Al-X-ray source with monochromator, measurement area: 400×200 μm) is subjected to the Shirley method to remove the background. 1s More specifically, "1s The "semi - quantitative value" can be the value of the peak area of O in the inorganic powder measured according to the manual of the X - ray photoelectron spectroscopy apparatus. 1s Here, the "Shirley method" refers to a method of determining the background shape to be subtracted by assuming that inelastic scattered electrons causing the background have no energy dependence and that the number of inelastic scattered electrons is proportional to the peak intensity.

[0051] (Use)

[0052] The inorganic powder of the present embodiment can provide a resin composition with excellent fluidity. Therefore, it can be preferably used as a filler for resins.

[0053] <Filler for resins>

[0054] The filler for resins of the present embodiment contains the above - mentioned inorganic powder. From the viewpoint of obtaining a resin composition with more excellent fluidity, the filler for resins can be composed only of the above - mentioned inorganic powder. In addition, the resin that can be compounded with the filler for resins of the present embodiment is not particularly limited, and conventionally known thermosetting resins and thermoplastic resins can be compounded.

[0055] [Manufacturing method of inorganic powder]

[0056] The manufacturing method of the inorganic powder of the present embodiment includes: dispersing raw material powder in a liquid containing cavitation bubbles (step (I)); and recovering the raw material powder from the above liquid and then drying it (step (II)). According to the manufacturing method of the present embodiment, an inorganic powder with a Hausner ratio of 1.00 to 1.33 can be efficiently manufactured.

[0057] <Step (I)>

[0058] The manufacturing method of the present embodiment includes dispersing raw material powder in a liquid containing cavitation bubbles (step (I)). In the present invention, "cavitation bubbles" refer to bubbles generated by vaporization when the liquid is in a low - pressure state.

[0059] As a method of dispersing raw material powder in a liquid containing cavitation bubbles, for example, methods such as putting raw material powder into a liquid containing cavitation bubbles and performing mechanical stirring, and methods of dispersing raw material powder in a liquid by using cavitation bubbles can be cited.

[0060] When the raw material powder is dispersed in a liquid containing cavitation bubbles, the expansion and contraction force generated by the cavitation bubbles due to the pressure difference will break the aggregated particles (including secondary particles) in the raw material powder. As a result, the proportion of primary particles in the raw material powder tends to increase. By recovering and drying such a raw material powder using the method described below, an inorganic powder with a small ratio of tapped density to bulk density, that is, a Hausner ratio in the range of 1.00 to 1.33, can be obtained. In the manufacturing method of the present embodiment, step (I) preferably includes dispersing the aggregated particles in the raw material powder using cavitation bubbles (i.e., breaking the aggregated particles). The above-mentioned dispersion includes breaking the aggregated particles into primary particles.

[0061] In addition, through step (I), the proportion of hydroxyl groups on the particle surface increases, etc., and thus the state of the particle surface becomes prone to change. This is also considered to be one of the reasons for obtaining an inorganic powder with a small Hausner ratio.

[0062] (Raw material powder)

[0063] The raw material powder is not particularly limited. An inorganic powder prepared by any method can be used as the raw material powder. In step (I), from the viewpoint of effectively breaking the aggregated particles, the average particle size (D50) of the raw material powder is preferably 0.05 to 30 μm, more preferably 0.5 to 25 μm. In addition, the specific surface area of the raw material powder can be 1 to 30 m 2 / g, or can also be 1 to 15 m 2 / g.

[0064] The Hausner ratio of the raw material powder is preferably 1.35 to 3.00, more preferably 1.50 to 2.50. By using a raw material powder with a Hausner ratio within the above range, it is easy to obtain the inorganic powder of the present embodiment.

[0065] (Cavitation bubbles)

[0066] As a method for preparing a liquid containing cavitation bubbles, for example, methods such as reducing the pressure of the liquid, using ultrasonic waves, and hydrodynamic methods can be cited. A commercially available device can be used to prepare a liquid containing cavitation bubbles by these methods. In one embodiment, a hydrodynamic method can also be adopted. For example, it is preferable to use a commercially available powder attracting continuous dissolution and dispersion device to prepare a liquid containing cavitation bubbles, and it is particularly preferable to generate cavitation bubbles while circulating the liquid.

[0067] A powder suction continuous dissolution and dispersion device generally has a mechanism for generating a flow rate by a stirring blade. In one embodiment, the rotation speed of the stirring blade is preferably 2,000 to 10,000 rpm, more preferably 4,000 to 9,000 rpm, further preferably 4,500 to 8,000 rpm, still more preferably 5,000 to 8,000 rpm, and particularly preferably 6,000 to 7,200 rpm.

[0068] In one embodiment, step (I) preferably includes generating cavitation bubbles in the liquid. That is, by generating cavitation bubbles when dispersing the raw material powder in the liquid, the aggregated particles in the raw material powder can be easily broken.

[0069] In one embodiment, the number of cavitation treatments calculated based on the rotation speed (rpm) and discharge amount of the stirring wing of the device is used as the treatment for generating cavitation bubbles, and it is preferably carried out 50 times or more, more preferably 100 times or more, and further preferably 150 times or more.

[0070] (Liquid)

[0071] In the manufacturing method of the present embodiment, the liquid for dispersing the raw material powder is not particularly limited as long as it has the effects of the present invention. From the viewpoint of ease of drying after treatment, it can be a liquid composed only of an organic solvent such as ethanol, or a mixed solution of water and an organic solvent.

[0072] In the case of a mixed solution of water and an organic solvent, the water content in the mixed solution is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. In one embodiment, the above liquid is particularly preferably a liquid composed only of water.

[0073] From the viewpoints of effectively generating cavitation in the liquid and suppressing the volatilization of the liquid, the liquid temperature in step (I) is preferably 10°C to 60°C, more preferably 20°C to 40°C.

[0074] The proportion of the raw material powder dispersed in the liquid is preferably 5 to 30% by mass, more preferably 5 to 20% by mass, and further preferably 5 to 15% by mass relative to the total of the liquid and the raw material powder (100% by mass). In one embodiment, the proportion of the above raw material powder can be 5 to 10% by mass or 8 to 10% by mass.

[0075] The time for implementing step (I) is not particularly limited as long as the effects of the present invention are achieved. From the viewpoint of easily improving the recovery efficiency of the powder after crushing or easily suppressing the deviation of crushing in the processed powder, the time of step (I) can be extended. In one embodiment, step (I) can be 5 minutes or more and 24 hours or less, can be 5 minutes or more and 20 hours or less, or can be 5 minutes or more and 10 hours or less.

[0076] <Step (II)>

[0077] Step (II) is a step of recovering the raw material powder from the liquid after step (I) and then drying it. As a method for recovering the raw material powder from the liquid, for example, filtration treatment (such as reduced-pressure filtration, vacuum filtration, etc.), centrifugal separation, etc. can be cited.

[0078] As a method for drying the recovered raw material powder, for example, hot air drying at high temperature, reduced-pressure drying, etc. can be cited.

[0079] In one embodiment, the drying temperature of the raw material powder is preferably 80°C to 150°C, more preferably 100°C to 120°C. In addition, the drying time is preferably 2 hours to 24 hours, more preferably 5 hours to 12 hours.

[0080] The manufacturing method of the present embodiment may include steps other than the above steps (I) and (II) (other steps). As other steps, for example, decomposition of inorganic powder, etc. can be cited.

[0081] [Resin composition]

[0082] The resin composition of the exemplary embodiment contains the above inorganic powder and at least one resin selected from the group consisting of a thermoplastic resin and a thermosetting resin.

[0083] The proportion of the inorganic powder in the resin composition is not particularly limited and can be appropriately adjusted according to the purpose. For example, it can be in the range of 1 to 99% by mass, or can be in the range of 5 to 80% by mass, relative to the total mass of the resin composition.

[0084] <Resin>

[0085] The resin composition of the exemplary embodiment contains at least one resin selected from thermoplastic resins and thermosetting resins. More specifically, for example, polyethylene resin; polypropylene resin; epoxy resin; silicone resin; phenolic resin; melamine resin; urea resin; unsaturated polyester resin; fluororesin; polyamide-based resins such as polyimide resin, polyamideimide resin, and polyetherimide resin; polyester-based resins such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyphenylene sulfide resin; wholly aromatic polyester resin; polysulfone resin; liquid crystal polymer resin; polyethersulfone resin; polycarbonate resin; maleimide-modified resin; ABS resin; AAS (acrylonitrile-acrylic rubber-styrene) resin; AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin; hydrocarbon-based elastomer resin; polyphenylene ether resin; aromatic polyene-based resin, etc. They can be used alone or in combination of two or more.

[0086] Within the range that does not impair the effects of the present invention, other additives can be incorporated into the resin composition. As other additives, rubber-like substances such as silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, styrene block copolymer, and saturated elastomer can be cited; resin-like substances such as silicone resin can be cited; resins obtained by modifying part or all of epoxy resin or phenolic resin with amino silicone, epoxy silicone, alkoxysilicone, etc.; flame retardant aids such as Sb2O3, Sb2O4, Sb2O5, etc.; flame retardants such as halogenated epoxy resin and phosphorus compounds; colorants such as carbon black, iron oxide, dyes, and pigments, etc. They can be used alone or in combination of two or more.

[0087] <Manufacturing method of resin composition>

[0088] The manufacturing method of the resin composition is not particularly limited, and it can be manufactured by stirring, dissolving, mixing, and dispersing the specified amounts of each material. The devices for mixing, stirring, dispersing, etc. of these mixtures are not particularly limited, and a kneader, three-roll mill, ball mill, planetary mixer, etc. equipped with stirring and heating devices can be used. In addition, these devices can also be used in appropriate combination.

[0089] Examples

[0090] Hereinafter, examples are shown to more specifically illustrate the present invention, but the interpretation of the present invention is not limited to these examples.

[0091] (Raw material powder)

[0092] As the raw material powder, the powder of the following inorganic metal compound is used.

[0093] Table 1

[0094]

[0095] In Table 1, the average particle diameter (D50), specific surface area, bulk density, tapped density of the raw material powder, and the viscosity (ρ1) of the resin composition are values measured under the same conditions as the inorganic powder described below.

[0096] [Example 1]

[0097] In ion-exchanged water in which cavitation bubbles were generated using a powder suction continuous dissolution and dispersion device (manufactured by Nippon Shippuden Co., Ltd., product name: Jetpaster (registered trademark), model: JPSS), the raw material powder 1 (10% by mass) was dispersed (Step (I)). In addition, after 60 minutes of performing Step (I) by rotating the stirring blade of the above device at 7,200 rpm to generate cavitation bubbles in the ion-exchanged water, a filtration treatment was performed to recover the raw material powder. Then, it was dried at 120 °C for 5 hours to obtain the inorganic powder (spherical boron nitride powder) of Example 1.

[0098] For the obtained inorganic powder, the average particle diameter (D50), specific surface area (BET specific surface area), O 1s semi-quantitative value, bulk density, and tapped density were measured under the following conditions. In addition, the fluidity of the resin composition containing the inorganic powder was evaluated under the following conditions. The results are shown in Table 2.

[0099] (Measurement of bulk density and tapped density)

[0100] The bulk density and tapped density of the inorganic powder were measured by the method shown below.

[0101] First, the inorganic powder was dried at 120 °C for 5 hours. Then, 5.00 ± 0.02 g (M1) of the dried inorganic powder was weighed using an analytical balance (an analytical balance with a minimum weighing value of 0.001 g) and put into a 50 mL graduated cylinder. After putting it in, the volume (V1) of the inorganic powder in the graduated cylinder was visually measured (to the first decimal place). Next, the graduated cylinder was lifted and dropped 500 times from a height of 3.5 cm. At this time, the graduated cylinder was dropped onto a rubber mat (thickness 40 mm) in such a way that the impact applied to the graduated cylinder was the same each time. After dropping 500 times, the volume (V2) of the inorganic powder in the graduated cylinder was visually measured (to the first decimal place). According to the following formulas (1) - (2), the bulk density and tapped density of the inorganic powder were calculated. The bulk density and tapped density were calculated to two decimal places by rounding the third decimal place. In addition, the bulk density and tapped density were calculated using "g / cm 3 " with a 1 mL graduated cylinder as 1 cm 3 ³. In addition, the above measurement of the tapped density and bulk density was performed under the conditions of a temperature of 23 °C and a humidity of 50%.

[0102] Bulk density (g / cm 3 ): Mass of inorganic powder (M1) / V1 ··· (1)

[0103] Tap density (g / cm 3 ): Mass of inorganic powder (M1) / V2 ··· (2)

[0104] Based on the above results, calculate the Hausner ratio (tap density / bulk density).

[0105] (Measurement of average particle size (D50))

[0106] After dispersing 0.01 g of the inorganic powder in 80 mL of ethanol, it was dispersed using a homogenizer, and the volume-based particle size distribution was measured using a laser diffraction scattering particle size distribution measuring device (manufactured by Beckman Coulter, product name: LS-13320). At this time, the refractive index of ethanol was 1.359. The average particle size (D50) (μm) was obtained from the resulting frequency particle size distribution.

[0107] (Measurement of specific surface area)

[0108] In accordance with JIS Z8830:2013, the BET specific surface area of the inorganic powder was measured by the BET multipoint method using nitrogen.

[0109] (O 1s semi-quantitative value measurement)

[0110] For the spectrum measured in accordance with the manual using an X-ray photoelectron spectroscopy device (manufactured by Thermo Fischer, product name: K-Alpha type X-ray photoelectron spectroscopy device, with a monochromatic Al-X-ray source, measurement area: 400×200 μm), the background was removed using the Shirley method, and the semi-quantitative value (i.e., the O 1s peak intensity) was calculated from the O 1s peak area).

[0111] The fluidity of the resin composition containing the inorganic powder was evaluated by the ratio of the shear viscosities of the raw material powder and the inorganic powder (the ratio of the shear viscosities before and after the cavitation treatment). Specifically, after preparing the resin composition by the following method, the ratio of the viscosities at a shear rate of 0.1 (1 / s) of the obtained resin composition was evaluated.

[0112] (Preparation of resin composition)

[0113] To an epoxy resin (manufactured by Nippon Steel Chemical Materials Co., Ltd., product name "YDF-8170C"), a dispersant (manufactured by BYK-Chemie Japan Co., Ltd., product name "DISPERBYK-111", 0.3 mass%), an SC material (manufactured by Tokyo Chemical Industry Co., Ltd., product name "3-glycidyloxypropyltrimethoxysilane", 1 mass%), and a raw material powder (15 mass%) were added, and kneaded for 3 minutes at room temperature, a revolution speed of 2,000 rpm, and a rotation speed of 800 rpm using a mixer (manufactured by THINKY Co., Ltd., product name "あわり仁太郎 (registered trademark) AR-250"). Then, kneading was performed twice using a three-roll mill (manufactured by AIMEX Co., Ltd., product name "BR-150VIII", gap: 10 μm, finishing roll speed: 60 rpm) to obtain a resin composition for evaluation (resin composition containing raw material powder (before cavitation treatment)). For the obtained resin composition, a rheometer (manufactured by Anton Paar, product name "MCR92") was used to change the shear rate from 0.01 (1 / s) to 100 (1 / s) at 25°C, and then the shear rate was changed from 100 (1 / s) to 0.01 (1 / s). The viscosity (ρ1) at a shear rate of 0.1 (1 / s) was measured. The results are shown in Table 1. Next, using the same method as above, resin compositions containing inorganic powder (15% by mass) of the examples and comparative examples were prepared, the viscosity at a shear rate of 0.1 (1 / s) was measured, the ratio relative to ρ1 was calculated, and then evaluated according to the following evaluation criteria. In the following evaluation criteria, B evaluation or above is qualified (the fluidity when filled with resin is improved). The results are shown in Table 2.

[0114] (Evaluation Criteria)

[0115] A: The ratio to ρ1 is 0.01 or less.

[0116] B: The ratio to ρ1 is more than 0.01 and is 0.25 or less.

[0117] C: The ratio to ρ1 is more than 0.25 and not more than 0.5.

[0118] D: The ratio to ρ1 exceeds 0.5.

[0119] [Example 2 to Example 7 and Comparative Example 1 to Comparative Example 4]

[0120] Inorganic powders were produced in the same manner as in Example 1, except that the types of raw material powders and the production conditions were as shown in Table 2. In Comparative Examples 1 to 4, the raw material powders were stirred and dispersed in a liquid without cavitation bubbles, and then the raw material powders were recovered by filtration and dried. For the inorganic powders obtained in each example, the average particle size (D50), specific surface area, bulk density, and tapped density were measured, and the fluidity of the resin composition containing the inorganic powder was evaluated, using the same method as in Example 1. In addition, in Examples 2 to 5 and Comparative Examples 1 to 2, the O 1s semi-quantitative value was measured using the same method as in Example 1. The results are shown in Table 2.

[0121] In Tables 1 and 2, the notation "-" indicates that the device was not used or the measurement was not performed.

[0122] Table 2

[0123]

[0124] As shown in Table 2, the inorganic powders of Examples 1 to 7 with a Hausner ratio of 1.00 to 1.33 had excellent fluidity. It was found that the fluidity of the inorganic powders of these examples was improved compared to the raw material powders. On the other hand, the fluidity evaluations of the inorganic powders of Comparative Examples 1 to 4, which did not satisfy the configuration of the present invention, were worse than those of the examples. From the above results, it was confirmed that the inorganic powders of the present embodiment could achieve excellent fluidity when compounded with a resin.

[0125] Industrial Applicability

[0126] The inorganic powders of the present embodiment can provide a resin composition with excellent fluidity. Therefore, they can be preferably used as fillers for resins.

Claims

1. An inorganic powder having a Hausner ratio of 1.00 to 1.

33.

2. The inorganic powder according to claim 1, wherein, Its average particle size D50 is 30 μm or less.

3. The inorganic powder according to claim 1 or 2, having a specific surface area of 0.3 m 2 / g or more.

4. The inorganic powder according to claim 1 or 2, containing at least one selected from alumina powder, aluminum nitride powder, silica powder, silicon nitride powder, magnesia powder, titanium oxide powder, zirconium oxide powder, zinc oxide powder, aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder.

5. The inorganic powder according to claim 1 or 2, being at least one selected from aggregated boron nitride powder, flaky boron nitride powder, and spherical boron nitride powder.

6. The inorganic powder according to claim 5, wherein, The semi-quantitative value calculated from the O peak intensity measured by X-ray photoelectron spectroscopy is 0.6 or more. 1s ​ 7. The inorganic powder according to claim 1 or 2, which is used for resin filling.

8. A filler for a resin, containing the inorganic powder according to claim 1 or 2.

9. A resin composition, containing the inorganic powder according to claim 1 or 2 and at least one resin selected from thermoplastic resins and thermosetting resins.

10. A method for manufacturing the inorganic powder according to claim 1 or 2, comprising: Disperse the raw material powder in a liquid containing cavitation bubbles; and recover the raw material powder from the liquid and then dry it.

11. The manufacturing method according to claim 10, wherein, The dispersion includes using the cavitation bubbles to disperse the aggregated particles in the raw material powder.

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