Spherical boron nitride powder, filler for resin, resin composition, and method for producing spherical boron nitride powder

Abstract

Provided are: a spherical boron nitride powder which can achieve excellent fluidity when blended into a resin; a filler for a resin, which contains the spherical boron nitride powder; and a resin composition which contains the spherical boron nitride powder. The spherical boron nitride powder according to the present invention has a tap density of 0.30 g / cm3 or more. The average particle diameter (D50) of the spherical boron nitride powder is preferably 2.0 [mu] m or less. It is preferable that the spherical boron nitride powder have an average particle diameter (D90) of 10.0 [mu] m or less and an average particle diameter (D10) of 0.5 [mu] m or less.

Description

Technical Field

[0001] The present invention relates to spherical boron nitride powder, a filler for resin, a resin composition, and a method for manufacturing spherical boron nitride powder. Background Art

[0002] Hexagonal boron nitride (hereinafter referred to as "boron nitride") has lubricity, high thermal conductivity, insulation properties, etc., and is widely used in solid lubricants, molten gases, release agents for aluminum, etc., and filler materials for heat dissipation materials.

[0003] As boron nitride fine particles that utilize the lubricity and high thermal conductivity characteristics of boron nitride, in Patent Document 1, there are described flaky boron nitride fine particles having a small diameter / thickness ratio (aspect ratio), which are submicron-sized, high-purity, and highly crystalline boron nitride fine particles. In addition, Patent Document 2 describes spherical boron nitride fine particles having a high sphericity and a method for manufacturing the same.

[0004] Prior Art

[0005] Patent Document 1: International Publication No. 2015 / 122378

[0006] Patent Document 2: International Publication No. 2015 / 122379 Summary of the Invention

[0007] Generally, when an inorganic filler is incorporated into a resin, there is a tendency for the fluidity of the resin composition to decrease. Therefore, an object of the present invention is to provide spherical boron nitride powder that can achieve excellent fluidity when incorporated into a resin, a filler for resin containing the above spherical boron nitride powder, and a resin composition containing the above spherical boron nitride powder.

[0008] The inventors of the present invention conducted in-depth research and found that if the tapped density of spherical boron nitride powder measured under specific conditions is a certain value or more, the above technical problems can be solved, and thus the present invention was completed.

[0009] That is, the present invention has the following aspects.

[0010] [1] A spherical boron nitride powder having a tapped density of 0.30 g / cm 3 or more.

[0011] [2] The spherical boron nitride powder according to [1], wherein the average particle diameter (D50) thereof is 2.0 μm or less.

[0012] [3] The spherical boron nitride powder according to [1] or [2], wherein the average particle diameter (D90) thereof is 10.0 μm or less, and the average particle diameter (D10) thereof is 0.5 μm or less.

[0013] [4] The spherical boron nitride powder according to any one of [1] to [3], wherein its average circularity is 0.70 or more.

[0014] [5] The spherical boron nitride powder according to any one of [1] to [4], wherein its specific surface area is 5 m 2 / g or more.

[0015] [6] The spherical boron nitride powder according to any one of [1] to [5], wherein the semi-quantitative value calculated based on the peak intensity of O 1s measured by X-ray photoelectron spectroscopy is 0.6 or more.

[0016] [7] The spherical boron nitride powder according to any one of [1] to [6], which is used for resin filling.

[0017] [8] A filler for resin, which contains the spherical boron nitride powder according to any one of [1] - [7].

[0018] [9] A resin composition, which contains the spherical boron nitride powder according to any one of [1] - [7] and at least one resin selected from thermoplastic resins and thermosetting resins.

[0019] According to the present invention, it is possible to provide a spherical boron nitride powder that can achieve excellent fluidity when compounded into a resin, a filler for resin containing the above spherical boron nitride powder, and a resin composition containing the above spherical boron nitride powder. Detailed Embodiments

[0020] 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 appropriately modified and implemented within the scope that does not hinder the effects of the present invention. When the specific description described in one embodiment is also applicable to other embodiments, the description thereof 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".

[0021] Each component and their combinations in each embodiment are examples, and within the scope not departing from the gist of the present invention, additions, omissions, substitutions, and other changes of the components can be appropriately made. The present invention is not limited by the embodiments. Each embodiment disclosed in this specification can also be combined with any other features disclosed in this specification.

[0022] In addition, the "spherical powder" in the present invention means that when observing the powder at a magnification of 10,000 times using a scanning electron microscope, the shape of the particles is observed to be circular or a particle shape with rounded corners. In addition, "powder" means an aggregate of particles.

[0023] Spherical boron nitride powder

[0024] The tapped density of the spherical boron nitride powder of this embodiment is 0.30 g / cm 3 or more. When the spherical boron nitride powder of this embodiment with a tapped density of 0.30 g / cm 3 or more is filled in a resin, a resin composition with excellent fluidity can be provided. In addition, the above-mentioned tapped density refers to the value measured by the following method.

[0025] (Method for measuring tapped density)

[0026] First, dry the spherical boron nitride powder at 120 °C for 5 hours. Then, weigh 5.00 ± 0.02 g (M1) of the dried spherical boron nitride powder with an analytical balance (an analytical balance with a minimum weighing value of 0.001 g), and put it into a 50 mL graduated cylinder. Next, lift the graduated cylinder and let it fall from a height of 3.5 cm for 500 times. At this time, make the impact applied to the graduated cylinder the same each time, and let the graduated cylinder fall onto a rubber pad (thickness 40 mm). After falling 500 times, visually measure the volume (V1) of the spherical boron nitride powder in the graduated cylinder (to the first decimal place). According to the following formula (1), calculate the tapped density of the spherical boron nitride powder. Round the third decimal place and calculate to two decimal places. In addition, the tapped density is calculated with 1 mL of the graduated cylinder as 1 cm 3 ³, and calculated in "g / cm 3 ³". In addition, the above-mentioned measurement of the tapped density is carried out under the conditions of a temperature of 21 - 25 °C and a humidity of 50% ± 4%.

[0027] Tapped density (g / cm 3 ³): Mass (M1) of spherical boron nitride powder / V1 ··· (1)

[0028] The spherical boron nitride powder of this embodiment has a tapped density of 0.30 g / cm 3 or more measured by the above method. Such spherical boron nitride powder with a high tapped density has been unknown in the past and is a new type of powder.

[0029] It is difficult to synthesize large particles of boron nitride powder with spherical primary particles, and it is easy to sinter into large-volume agglomerated or beaded shapes during firing, making it difficult to obtain a powder with a high tapped density. The spherical boron nitride powder of this embodiment can be made into a powder with a high tapped density that has been difficult to achieve in the past, for example, by using the method for manufacturing spherical boron nitride powder described later. The spherical boron nitride powder of this embodiment with such characteristics can provide a resin composition with excellent fluidity. In addition, as the reason for being able to provide a resin composition with excellent fluidity, it is speculated that it is because the tapped density of the spherical boron nitride powder of this embodiment is 0.30 g / cm 3As described above, the amount of irregularly shaped particles, agglomerates, etc. containing large voids in the powder is reduced, and since it is difficult to form a network structure of particles in the resin, etc., the viscosity of the resin composition can be lowered.

[0030] In one embodiment, the tapped density of the spherical boron nitride powder measured under the above conditions may be 0.40 g / cm 3 or more, and may also be 0.50 g / cm 3 or more. In addition, the upper limit is not particularly limited as long as the effects of the present invention are achieved. From the viewpoint of easily obtaining a resin composition having excellent fluidity, it may be 1.00 g / cm 3 or less, may be 0.80 g / cm 3 or less, and may also be 0.70 g / cm 3 or less. That is, the tapped density of the spherical boron nitride powder may be 0.30 to 1.00 g / cm 3 , may be 0.30 to 0.80 g / cm 3 , may be 0.30 to 0.70 g / cm 3 , may be 0.40 to 1.00 g / cm 3 , may be 0.40 to 0.80 g / cm 3 , may be 0.40 to 0.70 g / cm 3 , may be 0.50 to 1.00 g / cm 3 , may be 0.50 to 0.80 g / cm 3 , and may also be 0.50 to 0.70 g / cm 3 .

[0031] For example, by a production method including dispersing the raw material powder of the spherical boron nitride powder in a liquid containing cavitation bubbles and then recovering and drying it, it is possible to easily prepare spherical boron nitride powder having a tapped density of 0.30 g / cm 3 or more. Alternatively, it is easily achieved when the Hausner ratio, which is the ratio of the tapped density to the bulk density, is in the range of 1.00 to 1.33.

[0032] In one embodiment, the Hausner ratio (tapped density (g / cm 3 ) / bulk density (g / cm 3 )) of the spherical boron nitride powder is preferably 1.00 to 1.33, more preferably 1.00 to 1.25, further preferably 1.00 to 1.19, and particularly preferably 1.00 to 1.11. It should be noted that the bulk density of the spherical boron nitride powder can be measured by the following method.

[0033] (Method for measuring bulk density)

[0034] First, dry the spherical boron nitride powder at 120 °C for 5 hours. Then, weigh 5.00 ± 0.02 g (M2) of the dried spherical boron nitride powder using a precision balance (a precision 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 (V2) of the spherical boron nitride powder in the graduated cylinder (to the first decimal place). According to the following formula (2), calculate the bulk density of the spherical boron nitride powder. Round the bulk density to the third decimal place and calculate to two decimal places. In addition, set 1 mL of the graduated cylinder as 1 cm 3 , and calculate the bulk density in "g / cm 3 ". In addition, the above measurement of the bulk density is carried out under the conditions of a temperature of 21 - 25 °C and a humidity of 50% ± 4%.

[0035] Bulk density (g / cm 3 ): Mass (M2) of spherical boron nitride powder / V2 ··· (2)

[0036] <Average particle size>

[0037] The average particle size (D50) of the spherical boron nitride powder in this embodiment is preferably 2.0 μm or less. The average particle size (D50) of the spherical boron nitride 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 size at which the cumulative value is equivalent 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 with the particle size (μm) on the horizontal axis and the cumulative value (%) on the vertical axis.

[0038] Generally, the tapped density of inorganic powders tends to increase as the average particle size (D50) (hereinafter sometimes simply referred to as "D50") increases. The tapped density of the spherical boron nitride powder in this embodiment is 0.30 g / cm 3 or more, but the D50 is relatively small. In one embodiment, the D50 of the spherical boron nitride powder can be 1.5 μm or less, can be 1.0 μm or less, can be 0.9 μm or less, can be 0.8 μm or less, can be 0.7 μm or less. In addition, the lower limit of the D50 of the spherical boron nitride powder is not particularly limited as long as it has the effects of the present invention. For example, it can be 0.01 μm or more, can be 0.05 μm or more, can be 0.1 μm or more, can be 0.2 μm or more, can be 0.3 μm or more, or can be 0.4 μm or more. The D50 of the spherical boron nitride powder in this embodiment can adopt any combination of the above preferred upper and lower limits within the range where the tapped density is 0.30 g / cm 3 or more.

[0039] Even though the D50 of the spherical boron nitride powder of this embodiment is relatively small as described above, the tapped density is liable to be 0.30 g / cm 3 Thus, it is easy to obtain spherical boron nitride powder with excellent fluidity.

[0040] In one embodiment, it is preferable that the average particle diameter (D90) of the spherical boron nitride powder is 10.0 μm or less, and the average particle diameter (D10) is 0.5 μm or less. The average particle diameter (D90) refers to the volume-based cumulative diameter (D90) evaluated by the laser diffraction scattering method after performing a specific dispersion treatment, such as homogenizer treatment. In addition, the "volume-based cumulative diameter (D90)" refers to the particle diameter at which the cumulative value is equivalent to 90% 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 with the particle diameter (μm) on the horizontal axis and the cumulative value (%) on the vertical axis. The average particle diameter (D10) can also be measured by the same method as the average particle diameter (D90). The average particle diameter (D10) refers to the particle diameter (volume-based cumulative diameter (D10)) at which the cumulative value is equivalent to 10% in the volume-based cumulative particle size distribution measured by the laser diffraction scattering method.

[0041] If the average particle diameter (D90) and the average particle diameter (D10) of the spherical boron nitride powder are within the above ranges, it is easy to obtain spherical boron nitride powder with more excellent fluidity.

[0042] In one embodiment, the average particle diameter (D90) of the spherical boron nitride powder with D50 of 0.1 to 0.4 μm can be 0.10 to 0.8 μm, can be 0.25 to 1.0 μm, or can be 0.6 to 2.5 μm.

[0043] In addition, the average particle diameter (D10) of the spherical boron nitride powder with D50 of 0.1 to 0.4 μm can be 0.06 to 0.3 μm, can be 0.05 to 0.2 μm, or can be 0.02 to 0.1 μm.

[0044] In one embodiment, the average particle diameter (D90) of the spherical boron nitride powder with D50 exceeding 0.4 μm and being 1.0 μm or less can be 0.7 to 1.8 μm, can be 1.6 to 2.5 μm, or can be 2.4 to 6.0 μm.

[0045] In addition, the average particle diameter (D10) of the spherical boron nitride powder with D50 exceeding 0.4 μm and being 1.0 μm or less can be 0.2 to 0.7 μm, can be 0.2 to 0.5 μm, or can be 0.05 to 0.2 μm.

[0046] In one embodiment, the average particle size (D90) of spherical boron nitride powder with a D50 exceeding 1.0 μm and being 2.0 μm or less may be 1.8 to 3.6 μm, may be 2.5 to 5.0 μm, or may be 6.0 to 12 μm.

[0047] In addition, the average particle size (D10) of spherical boron nitride powder with a D50 exceeding 1.0 μm and being 2.0 μm or less may be 0.6 to 1.4 μm, may be 0.5 to 1.0 μm, or may be 0.1 to 0.4 μm.

[0048] <Average circularity>

[0049] In one embodiment, the average circularity of the spherical boron nitride powder may be 0.70 or more, may be 0.75 or more, may be 0.80 or more, or may be 0.87 or more. If the average circularity of the spherical boron nitride powder is 0.70 or more, it is likely to become spherical boron nitride powder with more excellent fluidity. In addition, the "average circularity" can be calculated by the following method.

[0050] (Method for measuring average circularity)

[0051] For an image of the powder taken with a scanning electron microscope (SEM) (magnification: 10,000 times, image resolution: 1280×1024 pixels), by using image analysis with image analysis software (for example, manufactured by Mountech Co., Ltd., product name: MacView), the projected area (S) and perimeter (L) of one particle are calculated. Substitute the projected area (S) and perimeter (L) into the following formula (3) to obtain the circularity. The average value of the circularities obtained for any 200 particles is taken as the average circularity.

[0052] Circularity = 4πS / L 2 …(3)

[0053] <Specific surface area>

[0054] Generally, the smaller the specific surface area, the easier it is for the tapped density of the inorganic powder to increase. In the case of the spherical boron nitride powder of the present embodiment, for example, in the case of the spherical boron nitride powder manufactured by the manufacturing method described later, even for spherical boron nitride powder with a large specific surface area, the tapped density can be increased. Here, a large specific surface area means that the BET specific surface area measured under the following conditions is 5 m 2 / g or more. In one embodiment, the specific surface area of the spherical boron nitride powder may be 5 m 2 / g or more, may be 6 m 2 / g or more, may be 7 m 2 / g or more, may be 8 m 2 / g or more, may be 9 m 2 / g or more, or can be 10 m 2 / g or more. The upper limit of the specific surface area is not particularly limited as long as the effects of the present invention are achieved, and can be 35 m 2 / g or less, can be 32 m 2 / g or less, can be 30 m 2 / g or less, can be 27 m 2 / g or less, can be 25 m 2 / g or less, can be 22 m 2 / g or less, can be 20 m 2 / g or less, can be 17 m 2 / g or less, or can be 15 m 2 / g or less. The specific surface area of the spherical boron nitride powder of this embodiment can be measured at a tapped density of 0.30 g / cm 3 Any combination of the above-mentioned preferred upper and lower limits can be selected within the range above.

[0055] (Method for measuring specific surface area)

[0056] According to JIS Z8830:2013, the BET specific surface area of boron nitride powder is measured by the BET multipoint method using nitrogen.

[0057] In one embodiment, the semi-quantitative value calculated based on the O 1s peak intensity of the spherical boron nitride powder measured by X-ray photoelectron spectroscopy is preferably 0.6 or more, more preferably 0.65 or more, and further preferably 0.7 or more. In the present invention, the "semi-quantitative value calculated based on the O 1s peak intensity" refers to the spectrum obtained by measuring the spherical boron nitride 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), removing the background by the Shirley method, and calculating the semi-quantitative value from the O 1s peak intensity. More specifically, the "O 1s semi-quantitative value" can be the value of the O 1s peak area in the inorganic powder measured according to the manual of the X-ray photoelectron spectrometer. Here, the "Shirley method" is a method for determining the background shape to be subtracted by assuming that the inelastic scattered electrons causing the background have no energy dependence and that the number of inelastic scattered electrons is proportional to the peak intensity.

[0058] As described above, the spherical boron nitride powder of the present embodiment can provide a resin composition with excellent fluidity. In one embodiment, the viscosity of the resin composition containing the spherical boron nitride powder of the present embodiment measured under the following conditions (viscosity at a shear rate of 0.1 (1 / s)) can be 100 Pa·s, can be 50 Pa·s or less, or can be 30 Pa·s or less.

[0059] (Method for measuring the viscosity of the resin composition)

[0060] To an epoxy resin (e.g., manufactured by Nippon Steel Chemical & Material Co., Ltd., product name "YDF-8170C"), 0.3 mass% of a dispersant (e.g., manufactured by BYK-Chemie Japan Co., Ltd., product name "DISPERBYK-111"), 1 mass% of an SC material (e.g., manufactured by Tokyo Chemical Industry Co., Ltd., product name "3-glycidoxypropyltrimethoxysilane"), and 15 mass% of the spherical boron nitride powder of the present embodiment are added. Using a mixing blender (e.g., manufactured by THINKY CORPORATION, product name "AWATORI RENGTARO (registered trademark) AR-250"), knead at normal temperature, a revolution speed of 2,000 rpm, and a rotation speed of 800 rpm for 3 minutes. Then, knead twice with a three-roll mill (e.g., manufactured by AIMEX CORPORATION, product name "BR-150VIII", gap: 10 μm, finishing roll rotation speed: 60 rpm) to obtain a resin composition for evaluation. For the obtained resin composition, using a rheometer (e.g., manufactured by Anton Paar GmbH, product name "MCR92"), at 25°C, change the shear rate from 0.01 (1 / s) to 100 (1 / s), and then change the shear rate from 100 (1 / s) to 0.01 (1 / s), and measure the viscosity at a shear rate of 0.1 (1 / s) among the measured viscosities.

[0061] (Use)

[0062] The spherical boron nitride powder of the present embodiment can provide a resin composition with excellent fluidity. Therefore, it can be preferably used as a filler for resins.

[0063] <Filler for resins>

[0064] The filler for resins of the present embodiment contains the above-mentioned spherical boron nitride 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 spherical boron nitride 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.

[0065] [Manufacturing method of spherical boron nitride powder]

[0066] The spherical boron nitride powder of the present embodiment can be prepared, for example, by a manufacturing method including dispersing raw material powder in a liquid containing cavitation bubbles (step (I)), recovering the raw material powder from the above liquid, and then drying it (step (II)). Hereinafter, one mode of the manufacturing method of the spherical boron nitride powder of the present embodiment including step (I) and step (II) will be described.

[0067] <Step (I)>

[0068] The manufacturing method of this mode 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 becomes in a low-pressure state.

[0069] As a method of dispersing raw material powder in a liquid containing cavitation bubbles, for example, there can be mentioned: a method of putting raw material powder into a liquid containing cavitation bubbles and performing mechanical stirring; a method of using cavitation bubbles to disperse raw material powder in the liquid, etc.

[0070] When dispersing raw material powder in a liquid containing cavitation bubbles, the expansion and contraction force generated by the pressure difference of the bubbles generated by cavitation 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 be high. By recovering and drying such raw material powder by the method described later, it is easy to obtain the spherical boron nitride powder with a tapped density of 0.30 g / cm 3 or more in the present embodiment. In the manufacturing method of this mode, it is preferable that step (I) includes dispersing (i.e., breaking) the aggregated particles in the raw material powder by cavitation bubbles. The above-mentioned dispersion also includes breaking the aggregated particles into primary particles.

[0071] In addition, through step (I), the proportion of the presence of hydroxyl groups on the particle surface increases, etc., and thus the state of the particle surface is likely to change. It is considered that this is also one of the reasons for easily obtaining the spherical boron nitride powder with a tapped density of 0.30 g / cm 3 or more.

[0072] (Raw material powder)

[0073] The raw material powder is not particularly limited, and spherical boron nitride powder prepared by any method can be used as the raw material powder. To more easily obtain a tapped density of 0.30 g / cm 3From the perspective of the above spherical boron nitride powder, the raw material powder is preferably prepared by the method described in Patent Document 2. That is, the molar ratio of ammonia / boric acid ester is 1 to 10, and in an inert gas stream, boric acid ester and ammonia are reacted at 750 °C or higher (preferably 750 to 1,300 °C, more preferably 800 to 1,200 °C) within 30 seconds to prepare a precursor of boron nitride powder. Then, the precursor of boron nitride powder is heat-treated at 1,000 to 1,600 °C for 1 hour or more (preferably 1 to 8 hours, more preferably 2 to 7 hours) in an atmosphere of ammonia or a mixed gas of ammonia and an inert gas to prepare a second precursor. Further, it is preferable to sinter the second precursor at 1,800 to 2,200 °C for 0.5 hour or more (preferably 2 to 8 hours, more preferably 3 to 7 hours) in an atmosphere of an inert gas to obtain the spherical boron nitride powder of the raw material.

[0074] As the boric acid ester, for example, trimethyl borate can be cited.

[0075] The average particle diameter (D50) of the raw material powder can be 0.01 μm or more, can be 0.05 μm or more, can be 0.1 μm or more, can be 0.2 μm or more, can be 0.3 μm or more, can be 0.4 μm or more. In addition, the upper limit thereof can be 1.0 μm or less, can be 0.9 μm or less, can be 0.8 μm or less, or can be 0.7 μm or less. As long as the D50 of the raw material powder is such that the tapped density of the obtained spherical boron nitride powder is 0.30 g / cm 3 In the above range, any combination of the above upper and lower limits can be adopted. In one embodiment, the D50 of the raw material powder can be 0.01 to 1.0 μm, or can be 0.3 to 0.8 μm. In addition, the average particle diameter (D50) of the raw material powder can be measured by the same method as that of the spherical boron nitride powder.

[0076] The average circularity of the raw material powder is preferably 0.70 or more, more preferably 0.75 or more, further preferably 0.8 or more, and particularly preferably 0.87 or more. The average circularity of the raw material powder can be measured by the same method as that of the spherical boron nitride powder.

[0077] The specific surface area of the raw material powder can be 5 to 30 m 2 / g, can be 6 to 27 m 2 / g, can be 7 to 25 m 2 / g, can be 8 to 22 m 2 / g, or can be 10 to 20 m 2 / g. It should be noted that the specific surface area of the raw material powder can also be measured by the same method as that of the spherical boron nitride powder.

[0078] (Cavitation bubbles)

[0079] As a method for preparing a liquid containing cavitation bubbles, for example, a method of reducing the pressure of the liquid, a method using ultrasonic waves, a hydrodynamic method, etc. 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 suction continuous dissolution and dispersion device to prepare a liquid containing cavitation bubbles, and it is particularly preferable to generate cavitation bubbles during liquid circulation.

[0080] 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 rotational 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 further preferably 5,000 to 8,000 rpm, and particularly preferably 6,000 to 7,200 rpm.

[0081] In one embodiment, it is preferable that step (I) 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.

[0082] In one embodiment, the number of cavitation treatments calculated based on the rotational speed (rpm) and discharge amount of the stirring blade 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, further preferably 150 times or more.

[0083] (Liquid)

[0084] In the manufacturing method of the present embodiment, the liquid in which the raw material powder is dispersed is not particularly limited as long as it has the effects of the present invention. From the viewpoints of ease of drying after treatment and compatibility with spherical boron nitride powder, it can be a liquid composed only of an organic solvent such as ethanol, or a mixed solution of water and an organic solvent.

[0085] 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, further preferably 95% by mass or more. In one embodiment, it is particularly preferable that the liquid is a liquid composed only of water.

[0086] 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 to 50 °C, more preferably 20 to 30 °C.

[0087] 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 still more preferably 5 to 15% by mass with respect 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 may be 5 to 10% by mass, or may be 8 to 10% by mass.

[0088] The time of the implementation process (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 process (I) can be extended. In one embodiment, process (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.

[0089] <Process (II)>

[0090] Process (II) is a process of recovering the raw material powder from the liquid after process (I) and then drying it. As a method of 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.

[0091] As a method of drying the recovered raw material powder, for example, high-temperature air-blowing drying, reduced-pressure drying, etc. can be cited.

[0092] In one embodiment, the drying temperature of the raw material powder is preferably 80 to 150 °C, more preferably 100 to 120 °C. In addition, the drying time is preferably 2 to 24 hours, more preferably 5 to 12 hours.

[0093] The manufacturing method of the present embodiment may include processes other than the aforementioned processes (I) and (II) (other processes). As other processes, for example, dispersing spherical boron nitride powder, etc. can be cited.

[0094] [Resin composition]

[0095] The resin composition of the present embodiment contains the above spherical boron nitride powder and at least one resin selected from thermoplastic resins and thermosetting resins.

[0096] The proportion of the spherical boron nitride 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. From the viewpoint of easily obtaining a resin composition with more excellent fluidity, the content of the spherical boron nitride powder in the resin composition is preferably 5 to 30% by volume, more preferably 10 to 25% by volume, and further preferably 15 to 20% by volume, relative to the total volume of the resin composition. In one embodiment, the content of the spherical boron nitride powder in the resin composition can be more than 5% by volume and 20% by volume or less.

[0097] In addition, from the viewpoint of maintaining fluidity and obtaining a resin composition with high thermal conductivity, the spherical boron nitride powder can be 50 to 80% by volume, can be 60 to 80% by volume, or can be 70 to 80% by volume, relative to the total volume of the resin composition. In one embodiment, the content of the spherical boron nitride powder in the resin composition can be more than 70% by volume and 80% by volume or less.

[0098] <Resin>

[0099] The resin composition of this 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 resins such as polyimide resin, polyamideimide resin, polyetherimide resin; polyester resins such as polybutylene terephthalate resin, 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 resin, etc. They can be used alone or in combination of two or more.

[0100] Within the scope not hindering the effects of the present invention, other additives can be incorporated into the resin composition. Examples of other additives include: rubber-like substances such as silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, styrene block copolymer, saturated elastomer, etc.; resin-like substances such as silicone resin; resins obtained by modifying a 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 or phosphorus compounds; colorants such as carbon black, iron oxide, dyes, pigments, etc. They can be used alone or in combination of two or more.

[0101] <Manufacturing method of resin composition>

[0102] The manufacturing method of the resin composition is not particularly limited and can be manufactured by stirring, dissolving, mixing, and dispersing a specified amount 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 be used in appropriate combination.

[0103] Examples

[0104] Hereinafter, the present invention will be described more specifically with reference to examples, but the interpretation of the present invention is not limited to these examples.

[0105] (Preparation of raw material powder)

[0106] The raw material powder (spherical boron nitride powder 1 of the raw material) was prepared through the following steps.

[0107] (1) The reaction tube (quartz tube) placed in the resistance heating furnace was heated to 1150 °C. Nitrogen was passed through trimethyl borate and then introduced into the reaction tube, whereby trimethyl borate was introduced into the reaction tube. Then, ammonia was directly introduced into the reaction tube. The molar ratio of the introduced amount of ammonia to the introduced amount of trimethyl borate (ammonia / trimethyl borate) was set to 1.8. Trimethyl borate and ammonia were reacted to obtain a precursor of boron nitride powder (white powder).

[0108] (2) The obtained precursor of boron nitride powder was placed in a boron nitride crucible placed in the resistance heating furnace, and nitrogen and ammonia were introduced into the reaction tube at flow rates of 10 L / minute and 15 L / minute, respectively. The reaction tube was heated at 1500 °C for 5 hours to obtain a second precursor.

[0109] (3) The obtained second precursor was placed in a boron nitride crucible and heated in an induction heating furnace at 2000 °C for 5 hours in a nitrogen atmosphere to obtain the raw material powder (spherical boron nitride powder of the raw material).

[0110] [Examples 1 to 5 and Comparative Example 1]

[0111] In ion-exchanged water in which cavitation bubbles are generated by a powder suction continuous dissolution and dispersion device (manufactured by Nippon Shippei Co., Ltd., product name: Jetpaster (registered trademark), model: JPSS), the raw material powder (10% by mass) was dispersed (Step (I)). In addition, the cavitation bubbles in the ion-exchanged water were generated by setting the rotation speed of the stirring blade of the above device to the values shown in Table 1. After performing Step (I), the raw material powder was recovered by filtration. Then, the raw material powder was dried at the temperature and for the time shown in Table 1 to obtain the spherical boron nitride powders of Examples 1 to 5. In Comparative Example 1, Steps (I) and (II) described above were not performed.

[0112] For the spherical boron nitride powders of each example, the tapped density, average particle size (D50), average particle size (D90), average particle size (D10), specific surface area, average circularity, and O 1s semi-quantitative value were measured under the following conditions. In addition, the fluidity of the resin composition containing the spherical boron nitride powder was evaluated under the following conditions. The results are shown in Table 1.

[0113] (Measurement of tapped density)

[0114] First, the spherical boron nitride powder was dried at 120 °C for 5 hours. Then, 5.00 ± 0.02 g (M1) of the dried spherical boron nitride powder was weighed using a precision balance (precision balance with a minimum weighing value of 0.001 g) and put into a 50 mL graduated cylinder. Next, the graduated cylinder was lifted and dropped from a height of 3.5 cm 500 times. At this time, the graduated cylinder was dropped onto a rubber pad (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 (V1) of the spherical boron nitride powder in the graduated cylinder was visually measured (to the first decimal place). According to the following formula (1), the tapped density of the spherical boron nitride powder was calculated. The tapped density was rounded to the third decimal place and calculated to two decimal places. In addition, the tapped density was calculated in units of 1 mL of the graduated cylinder as 1 cm 3 and expressed in "g / cm 3 ". In addition, the above measurement of the tapped density was performed under the conditions of a temperature of 23 °C and a humidity of 50%.

[0115] Tapped density (g / cm 3 ): Mass (M1) of spherical boron nitride powder / V1 ··· (1)

[0116] (Measurement of average particle sizes (D10), (D50), and (D90))

[0117] 0.01 g of spherical boron nitride powder was dispersed in 80 mL of ethanol, and then dispersed using a homogenizer. The volume-based particle size distribution was measured using a laser diffraction scattering particle size distribution measuring device (manufactured by Beckman Coulter, trade name: LS-13320). At this time, the refractive index of ethanol was 1.359. In the obtained frequency particle size distribution, the average particle sizes (D10), (D50), and (D90) (μm) were calculated from the particle diameters corresponding to cumulative values of 10%, 50%, and 90%, respectively.

[0118] (Measurement of specific surface area)

[0119] According to JIS Z8830:2013, the BET specific surface area of spherical boron nitride powder was measured by the BET multi-point method using nitrogen.

[0120] (O 1s (Measurement of semi-quantitative value)

[0121] The spectrum measured using an X-ray photoelectron spectroscopy device (manufactured by Thermo Fischer, product name: K-Alpha type X-ray photoelectron spectroscopy device, Al-X-ray source with monochromator, measurement area: 400×200 μm) according to the manual was background-corrected using the Shirley method, and the semi-quantitative value (i.e., the O 1s peak intensity) was calculated from the O 1s peak area.

[0122] The fluidity of the resin composition containing spherical boron nitride powder was evaluated under the following conditions.

[0123] (Viscosity measurement of resin composition (fluidity evaluation))

[0124] To the epoxy resin (manufactured by Nippon Steel Chemical 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-glycidoxypropyltrimethoxysilane", 1 mass%), and the spherical boron nitride powder of Examples and Comparative Examples (15 mass%) were added. Using a mixing blender (manufactured by THINKY CORPORATION, product name "AVATOR MIXER (registered trademark) AR-250"), kneading was performed at normal temperature, a revolution speed of 2,000 rpm, and a rotation speed of 800 rpm for 3 minutes. Then, using a three-roll mill (manufactured by AIMEX CORPORATION, product name "BR-150VIII", gap: 10 μm, finishing roll rotation speed: 60 rpm), kneading was performed twice to obtain a resin composition for evaluation. For the obtained resin composition, using a rheometer (manufactured by Anton Paar GmbH, product name "MCR92"), at 25°C, the shear rate was changed from 0.01 (1 / s) to 100 (1 / s), and then the shear rate was changed from 100 (1 / s) to 0.01 (1 / s), and the viscosity at a shear rate of 0.1 (1 / s) in the measured viscosity was measured. In addition, evaluation was performed according to the following evaluation criteria, and C evaluation or above was regarded as qualified.

[0125] (Evaluation Criteria)

[0126] A: The viscosity at a shear rate of 0.1 (1 / s) is 10 Pa·s or less.

[0127] B: The viscosity at a shear rate of 0.1 (1 / s) exceeds 10 Pa·s and is 50 Pa·s or less.

[0128] C: The viscosity at a shear rate of 0.1 (1 / s) exceeds 50 Pa·s and is 100 Pa·s or less.

[0129] D: The viscosity at a shear rate of 0.1 (1 / s) exceeds 100 Pa·s.

[0130] Table 1

[0131]

[0132] As shown in Table 1, it can be seen that the resin compositions of the spherical boron nitride powders of Examples 1 to 5 with a tapped density of 0.30 g / cm 3 or more have low viscosity and excellent fluidity. On the other hand, as shown in Comparative Example 1, the tapped density of the existing spherical boron nitride powder is less than 0.30 g / cm 3, it does not meet the composition of the present invention. Compared with the spherical boron nitride powders of Examples 1 to 5, such spherical boron nitride powders have a high viscosity and poor fluidity of the resin composition. From the above results, it can be confirmed that the spherical boron nitride powder of the present embodiment can achieve excellent fluidity when incorporated into a resin.

[0133] Industrial Applicability

[0134] The spherical boron nitride powder of the present embodiment can provide a resin composition with excellent fluidity. Therefore, it can preferably be used as a filler for resins.

Claims

1. A spherical boron nitride powder having a tapped density of 0.30 g / cm 3 or more.

2. The spherical boron nitride powder according to claim 1, wherein, Its average particle size D50 is 2.0 μm or less.

3. The spherical boron nitride powder according to claim 1 or 2, wherein, Its average particle size D90 is 10.0 μm or less, and the average particle size D10 is 0.5 μm or less.

4. The spherical boron nitride powder according to claim 1 or 2, wherein, Its average circularity is 0.70 or more.

5. The spherical boron nitride powder according to claim 1 or 2, wherein, Its specific surface area is 5 m 2 / g or more.

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

8. A filler for resin, which contains the spherical boron nitride powder according to claim 1 or 2.

9. A resin composition, which contains the spherical boron nitride powder according to claim 1 or 2 and at least one resin selected from thermoplastic resins and thermosetting resins.

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