WO2021193765A1 - Boron nitride particles and method for producing same, and resin composition and receptor containing said boron nitride particles - Google Patents

Boron nitride particles and method for producing same, and resin composition and receptor containing said boron nitride particles Download PDF

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WO2021193765A1
WO2021193765A1 PCT/JP2021/012391 JP2021012391W WO2021193765A1 WO 2021193765 A1 WO2021193765 A1 WO 2021193765A1 JP 2021012391 W JP2021012391 W JP 2021012391W WO 2021193765 A1 WO2021193765 A1 WO 2021193765A1
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boron nitride
nitride particles
particles
resin composition
resin
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PCT/JP2021/012391
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French (fr)
Japanese (ja)
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建治 宮田
祐輔 佐々木
啓 久保渕
智成 宮崎
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デンカ株式会社
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/38—Boron-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds

Definitions

  • the present disclosure relates to boron nitride particles and a method for producing the same, and a resin composition and an inclusion body containing the boron nitride particles.
  • heat dissipation members are used to efficiently dissipate heat generated during use.
  • the heat radiating member contains, for example, ceramic particles having high thermal conductivity.
  • ceramic particles boron nitride particles having characteristics such as high thermal conductivity, high insulation, and low relative permittivity are attracting attention.
  • Patent Document 1 is characterized by having an average particle size of 0.01 to 1.0 ⁇ m, an orientation index of 1 to 15, a boron nitride purity of 98.0% by mass or more, and an average circularity of 0.80 or more. Spherical boron nitride fine particles and a method for producing the same are disclosed.
  • a borate alkoxide having a molar ratio of ammonia / borate alkoxide of 1 to 10 and ammonia are reacted in an inert gas stream at 750 ° C. or higher and within 30 seconds, and then ammonia.
  • the boron nitride particles are used as a filler for primary sealing of electronic components as described above, they are usually mixed with a resin and used in the form of a resin composition. It is desirable to make the viscosity of the resin composition as low as possible.
  • one aspect of the present invention is to produce boron nitride particles capable of forming a low-viscosity resin composition.
  • One aspect of the present invention is a first step of reacting boric acid ester and ammonia at 750 to 1400 ° C. to obtain a precursor of boron nitride particles, and heating the precursor at 1000 to 1600 ° C. to obtain boron nitride particles.
  • This is a method for producing boron nitride particles, which comprises a second step of obtaining the boron nitride particles, and does not include a step of heating the boron nitride particles at 1800 ° C. or higher after the second step.
  • the reason why the boron nitride particles obtained by the above-mentioned production method can form a low-viscosity resin composition is that the boron nitride particles have a shape extremely close to a sphere. It is presumed that this is because of the fact.
  • another aspect of the present invention is boron nitride particles containing a plurality of boron nitride crystallites, which exhibit a circular planar shape when observed with a transmission electron microscope in a field of view of 100,000 times. It is a boron particle.
  • the average particle size of the boron nitride particles may be 1 ⁇ m or less.
  • the average circularity of the boron nitride particles may be 0.8 or more.
  • Another aspect of the present invention is a resin composition containing a resin and the above-mentioned boron nitride particles.
  • Another aspect of the present invention is an accommodating body including the above-mentioned boron nitride particles and a container for accommodating the boron nitride particles.
  • boron nitride particles capable of forming a low-viscosity resin composition can be produced.
  • One embodiment of the present invention includes a first step of reacting boric acid ester and ammonia at 750 to 1400 ° C. to obtain a precursor of boron nitride particles, and heating the precursor at 1000 to 1600 ° C. to obtain boron nitride particles.
  • a method for producing boron nitride particles which comprises a second step of obtaining particles.
  • a reaction tube for example, a quartz tube installed in a resistance heating furnace is heated to raise the temperature to 750 to 1500 ° C.
  • the boric acid ester is introduced into the reaction tube by passing the inert gas through the liquid boric acid ester and then introducing it into the reaction tube.
  • ammonia gas is introduced directly into the reaction tube.
  • the inert gas include rare gases such as helium, neon and argon, and nitrogen gas.
  • the borate ester may be, for example, an alkyl borate ester, preferably trimethyl borate.
  • the molar ratio of the amount of ammonia introduced to the amount of boric acid introduced may be, for example, 1 or more and 10 or less.
  • the introduced boric acid ester and ammonia react in a heated reaction tube to produce a precursor of boron nitride particles.
  • the precursor contains, for example, amorphous or low crystalline boron nitride and may be a white powder.
  • a part of the generated precursor adheres to the inside of the reaction tube, but most of the precursor is sent to the recovery container attached to the tip of the reaction tube by the inert gas or unreacted ammonia gas and recovered.
  • the time (reaction time) for reacting the boric acid ester with ammonia in the first step is preferably within 30 seconds.
  • the reaction time is the time during which the boric acid ester and ammonia stay in the portion of the reaction tube heated to 750 to 1400 ° C. (heated portion), and the gas flow rate when introducing the boric acid ester and ammonia and resistance heating. It can be adjusted by the length of the reaction tube installed in the furnace (the length of the heated portion of the reaction tube).
  • the precursor obtained in the first step is placed in another reaction tube (for example, an alumina tube) installed in the resistance heating furnace, and nitrogen gas and ammonia gas are separately placed in the reaction tube. Introduce.
  • the gas introduced at this time may be only ammonia gas.
  • the flow rates of nitrogen gas and ammonia gas may be appropriately adjusted so that the reaction time becomes a desired value, respectively. For example, the higher the flow rate of ammonia gas, the shorter the reaction time.
  • the reaction tube is heated to 1000 to 1600 ° C.
  • the heating time may be, for example, 1 hour or more and 10 hours or less.
  • the crystallization of boron nitride in the precursor is promoted to obtain boron nitride particles.
  • all the boron nitride in the precursor is not crystallized, and low crystalline boron nitride remains inside the boron nitride particles.
  • This manufacturing method does not include a step of heating the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. That is, in this production method, the desired boron nitride particles can be obtained without performing the third stage heating as disclosed in Patent Document 1 described above.
  • the boron nitride particles obtained in the second step are subjected to 1700 ° C. or higher, 1600 ° C. or higher, 1500 ° C. or higher, 1400 ° C. or higher, 1300 ° C. or higher, 1200 ° C. or higher, 1100.
  • °C or more 1000 °C or more, 900 °C or more, 800 °C or more, 700 °C or more, 600 °C or more, 500 °C or more, 400 °C or more, 300 °C or more, 200 °C or more, 100 °C or more, 50 °C or more, 40 °C or more Or, it does not have to be provided with a step of heating at 30 ° C. or higher.
  • the boron nitride particles obtained by the production method described above have a shape closer to a sphere than the conventional one.
  • Another embodiment of the present invention is a boron nitride particle that exhibits a circular planar shape when observed with a transmission electron microscope in a field of view of 100,000 times. The observation is performed using a transmission electron microscope (for example, "JEM-2100" manufactured by JEOL Ltd.) under the following conditions.
  • Objective lens aperture ⁇ 120 ⁇ m
  • Condenser lens aperture ⁇ 150 ⁇ m
  • the boron nitride particles have such a shape
  • the above-mentioned production method does not include a step of heating the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. It is thought that this is due to.
  • a circular planar shape is formed when observed under the above conditions. Boron nitride particles that do not exhibit the above can be obtained.
  • the boron nitride particles include, for example, a central portion containing low-crystalline boron nitride and a peripheral portion containing highly crystalline boron nitride arranged so as to surround the central portion.
  • the difference in crystallinity that can occur between the central portion and the peripheral portion is that the above-mentioned production method involves heating the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. It is thought that this is due to not having it.
  • high crystallinity is derived from the h-BN (0002) plane in the range of 1 to 4 nm -1 on the reciprocal lattice space in the FFT image of the boron nitride particles obtained by the following method. It means a state in which a bright spot (peak) is present due to the periodicity of the above, and “low crystallinity” means a state in which the bright spot (peak) does not exist.
  • the existence of a bright spot (peak) means that the intensity S after subtracting the background by the B-spline method in the range of 1 to 4 nm -1 on the reciprocal lattice space is 15 times or more the noise intensity N. It means that there is a point that becomes.
  • the noise intensity N is defined as the value of the standard deviation in the range of more than 4 nm -1 and 6 nm -1 or less on the reciprocal lattice space after performing background processing by the B-spline method.
  • the bright spots (peaks) include those having fluctuations in the wave number direction or the circumferential direction.
  • the intensity S is preferably 20 times or more, more preferably 23 times the noise intensity N in the range of 1 to 4 nm -1 on the reciprocal lattice space. As mentioned above, there may be a point that is more preferably 25 times or more.
  • FFT image acquisition method First, using a transmission electron microscope (for example, "JEM-2100” manufactured by JEOL Ltd.), a TEM image of 400,000 times that of boron nitride particles is obtained under the following conditions. Objective lens aperture: ⁇ 120 ⁇ m Condenser lens aperture: ⁇ 150 ⁇ m Recording medium: "Orisus SC1000A1" manufactured by AMETEK Bining: 2 Exposure time: 0.5 seconds In addition, image analysis software (for example, "GMS3" manufactured by AMETEC) is used for TEM observation and FFT analysis described later. Subsequently, an FFT analysis is performed on a region of 8.556 nm square in the obtained TEM image, and an FFT image of 256 ⁇ 256 pixels is acquired.
  • a transmission electron microscope for example, "JEM-2100” manufactured by JEOL Ltd.
  • the boron nitride crystallite means the smallest unit of a boron nitride crystal seen when observed with a transmission electron microscope in a field of view of 400,000 times. The observation is performed by the same transmission electron microscope and conditions as in the above-mentioned "Method for acquiring FFT image".
  • the boron nitride crystallite has, for example, a plate shape.
  • the plate-shaped boron nitride crystallite may be in the shape of a flat plate or may be in the shape of a curved plate.
  • plate-shaped boron nitride crystallites may be arranged so as to be laminated in the lateral direction.
  • the outermost surface of the boron nitride particles may have irregularities composed of boron nitride crystallites when observed with a transmission electron microscope in a field of view of 400,000 times. The observation is performed by the same transmission electron microscope and conditions as in the above-mentioned "Method for acquiring FFT image". More specifically, when the boron nitride particles are observed in the field of view, the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles is composed of a plurality of plate-shaped boron nitride crystals, and the plurality of the boron nitride particles are formed.
  • the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles may be uneven.
  • the unevenness may be within the range of 10 nm ⁇ 10 nm in the above field of view.
  • the unevenness may have at least one concave portion and one convex portion within the range of 10 nm ⁇ 10 nm in the above field of view.
  • the unevenness that may occur on the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles is such that the above-mentioned manufacturing method uses the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. It is considered that this is due to the fact that it does not have a process of heating with.
  • the diameter of the central portion of the boron nitride particles may be, for example, 0.1d or more, 0.15d or more, or 0.2d or more, and 0.6d or less, where d is the particle size of the boron nitride particles. , 0.5 or less, 0.4d or less, 0.35d or less, or 0.3d or less.
  • the diameter of the central portion in the boron nitride particles may be, for example, 1 nm or more, 5 nm or more, 10 nm or more, 20 nm or more, or 30 nm or more, and may be 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less.
  • the diameter of the central portion in the boron nitride particles is derived from the h-BN (0002) plane in the “highly crystalline” portion defined as described above, that is, in the range of 1 to 4 nm -1 on the reciprocal lattice space. It means the diameter of the part where the bright spot (peak) exists due to the periodicity of.
  • the thickness of the peripheral portion in the boron nitride particles may be, for example, 0.3d or more, 0.33d or more, or 0.35d or more, and 0.45d or more, where d is the particle size of the boron nitride particles. Hereinafter, it may be 0.43d or less, or 0.4d or less.
  • the diameter of the central portion in the boron nitride particles may be, for example, 5 nm or more, 10 nm or more, 20 nm or more, 40 nm or more, or 60 nm or more, and may be 450 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less.
  • the thickness of the peripheral portion in the boron nitride particles is the h-BN (0002) plane in the “low crystallinity” portion defined as described above, that is, in the range of 1 to 4 nm -1 on the reciprocal lattice space. It means the thickness of the part where there is no bright spot (peak) due to the periodicity of origin.
  • the average particle size of the boron nitride particles is preferably 0.01 ⁇ m or more, 0.05 ⁇ m or more, 0.1 ⁇ m or more, or 0. 1 ⁇ m or less, 0.8 ⁇ m or less, 0.6 ⁇ m or less, or 0.4 ⁇ m from the viewpoint of improving the insulation failure characteristics of the heat radiating member (hereinafter, also simply referred to as “radiating member”) which is 15 ⁇ m or more and contains boron nitride particles. It may be:
  • the average particle size of the boron nitride particles is measured by the following procedure. Distilled water is used as a dispersion medium for dispersing the boron nitride particles, and sodium hexametaphosphate is used as a dispersant to prepare a 0.125 mass% sodium hexametaphosphate aqueous solution. Boron nitride particles are added to this aqueous solution at a ratio of 0.1 g / 80 mL, and ultrasonic dispersion is performed with an ultrasonic homogenizer (for example, manufactured by Nissei Tokyo Office, trade name: US-300E) at 80% AMPLITUDE (amplitude).
  • an ultrasonic homogenizer for example, manufactured by Nissei Tokyo Office, trade name: US-300E
  • a dispersion of boron nitride particles is prepared by performing this once every 1 minute and 30 seconds. This dispersion is separated while stirring at 60 rpm, and the volume-based particle size distribution is measured by a laser diffraction / scattering method particle size distribution measuring device (for example, manufactured by Beckman Coulter, trade name: LS-13 320). At this time, 1.33 is used as the refractive index of water, and 1.7 is used as the refractive index of the boron nitride particles. From the measurement results, the average particle size is calculated as a particle size (median diameter, d50) of 50% of the cumulative value of the cumulative particle size distribution. The average particle size measured in this way is considered to be the average particle size of the boron nitride particles including the primary particles of the boron nitride particles and the particles (secondary particles) in which the primary particles are aggregated. ..
  • the average circularity of the boron nitride particles is preferably 0.8 from the viewpoint of improving the filling property when manufacturing the heat radiating member and making the characteristics (thermal conductivity, dielectric constant, etc.) of the heat radiating member isotropic. 0.82 or more, 0.84 or more, 0.86 or more, 0.88 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, or 0.94 or more. good.
  • the average circularity of the boron nitride particles is measured by the following procedure.
  • Image analysis software for example, manufactured by Mountech, trade name: MacView
  • SEM scanning electron microscope
  • the projected area (S) and the peripheral length (L) of the boron nitride particles are calculated by image analysis using.
  • Circularity 4 ⁇ S / L 2 Calculate the circularity according to.
  • the average value of the circularity obtained for 100 arbitrarily selected boron nitride particles is defined as the average circularity.
  • the above-mentioned boron nitride particles are suitably used for, for example, a heat radiating member.
  • the boron nitride particles are used, for example, in the form of a resin composition mixed with a resin.
  • another embodiment of the present invention is a resin composition containing the resin and the above-mentioned boron nitride particles.
  • This resin composition can have a lower viscosity than the conventional one, and is suitably used as a heat radiating member.
  • the content of the above-mentioned boron nitride particles is preferably 30% by volume or more, based on the total volume of the resin composition, from the viewpoint of improving the thermal conductivity of the resin composition and easily obtaining excellent heat dissipation performance. It is preferably 40% by volume or more, more preferably 50% by volume or more, and preferably 85% by volume or less, more preferably 85% by volume or less, from the viewpoint of suppressing the generation of voids during molding and the decrease in insulating property and mechanical strength. It is 80% by volume or less, more preferably 70% by volume or less.
  • the resin examples include epoxy resin, silicone resin, silicone rubber, acrylic resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide, polybutylene terephthalate, polyethylene terephthalate, and the like.
  • the content of the resin may be 15% by volume or more, 20% by volume or more, or 30% by volume or more, based on the total volume of the resin composition, and is 70% by volume or less, 60% by volume or less, or 50% by volume. It may be:
  • the resin composition may further contain a curing agent that cures the resin.
  • the curing agent is appropriately selected depending on the type of resin.
  • examples of the curing agent include phenol novolac compounds, acid anhydrides, amino compounds, and imidazole compounds.
  • the content of the curing agent may be, for example, 0.5 parts by mass or more or 1.0 part by mass or more, and may be 15 parts by mass or less or 10 parts by mass or less with respect to 100 parts by mass of the resin.
  • the above-mentioned boron nitride particles can be distributed, for example, in a form housed in a container. That is, another embodiment of the present invention is an accommodating body including the above-mentioned boron nitride particles and a container for accommodating the boron nitride particles.
  • the container may have a shape capable of accommodating boron nitride particles, and may be, for example, a bag, a box, a bottle, a can, or the like.
  • Example 1 (Preparation of boron nitride particles)
  • the reaction tube (quartz tube) installed in the resistance heating furnace was heated to raise the temperature to 1150 ° C.
  • trimethyl borate was introduced into the reaction tube by passing nitrogen gas through trimethyl borate and then introducing it into the reaction tube.
  • ammonia gas was introduced directly into the reaction tube.
  • the molar ratio of the amount of ammonia introduced to the amount of trimethyl borate introduced was 4.5.
  • trimethyl borate was reacted with ammonia to obtain a precursor (white powder) of boron nitride particles.
  • the reaction time was 10 seconds.
  • the precursor obtained in the first step is placed in another reaction tube (alumina tube) installed in the resistance heating furnace, and nitrogen gas 10 L / min and ammonia gas 15 L. Each was introduced into the reaction tube separately at a flow rate of / min. Then, the reaction tube was heated at 1500 ° C. for 2.5 hours. As a result, boron nitride particles were obtained.
  • alumina tube alumina tube
  • FIG. 1 shows a TEM bright-field image (magnification: 100,000 times) of the obtained boron nitride particles as a whole. Further, an enlarged image of one of the boron nitride particles shown in FIG. 1 was observed in FIG. 2 (a) at a magnification of 400,000 with respect to the peripheral portion S of the boron nitride particles shown in FIG. 2 (a). TEM dark-field images are shown in FIG. 2 (b), respectively.
  • the boron nitride particles had a circular planar shape.
  • the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles is composed of a plurality of plate-shaped boron nitride crystals, and the plurality of plate-shaped boron nitride crystals.
  • the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles was uneven because the particles were arranged so as to extend in different directions. This unevenness was within the range of 10 nm ⁇ 10 nm.
  • FIG. 4 FFT analysis was performed on the other regions S2 to S5 in the peripheral portion S of the boron nitride particles in the same manner as in the region S1.
  • FIGS. 4 and 5 bright spots (peaks) due to periodicity derived from the h-BN (0002) plane were confirmed in the range of 1 to 4 nm -1 on the reciprocal lattice space. That is, it was confirmed that the regions S2 to S5 in the peripheral portion S of the boron nitride particles were also composed of highly crystalline boron nitride.
  • FIG. 6 shows a TEM dark-field image of the central portion C of the boron nitride particles shown in FIG. 1 observed at a magnification of 400,000.
  • FFT analysis was performed on the other regions C1 to C4 in the central portion C of the boron nitride particles in the same manner as in the region S1.
  • no bright spot (peak) due to periodicity derived from the h-BN (0002) plane was confirmed in the range of 1 to 4 nm -1 on the reciprocal lattice space. That is, it was confirmed that the regions C1 to C4 in the central portion C of the boron nitride particles are composed of low crystallinity boron nitride.
  • the graphs shown in FIGS. 3 (b), 5 and 7 are graphs showing the intensity after subtracting the background by the B-spline method. Further, from the graphs shown in FIGS. 5 and 7 of FIG. 3B, the maximum intensity (relative intensity) Smax in the range of 1 to 4 nm -1 on the reciprocal lattice space for each of the regions S1 to S5 and C1 to C4. The noise intensity (standard deviation in the range of more than 4 nm -1 and 6 nm -1 or less on the reciprocal lattice space) N and their ratio (Smax / N) were obtained. The results are shown in Table 1.
  • the obtained boron nitride particles contain highly crystalline boron nitride in the peripheral portion (the region where the above-mentioned bright spot (peak) can be confirmed is dominant), and the central portion is low. It was found that crystalline boron nitride was contained (the region where the above-mentioned bright spot (peak) could not be confirmed was dominant).
  • the diameter of the central portion was about 40 nm, and the thickness of the peripheral portion was about 50 nm.
  • Distilled water was used as a dispersion medium for dispersing the boron nitride particles, and sodium hexametaphosphate was used as a dispersant to prepare a 0.125 mass% sodium hexametaphosphate aqueous solution.
  • Boron nitride particles are added to this aqueous solution at a ratio of 0.1 g / 80 mL, and ultrasonic dispersion is performed with an ultrasonic homogenizer (manufactured by Nissei Tokyo Office, trade name: US-300E) at 80% AMPLITUDE (amplitude).
  • a dispersion of boron nitride particles was prepared by performing this once every 1 minute and 30 seconds.
  • This dispersion was separated while stirring at 60 rpm, and the volume-based particle size distribution was measured with a laser diffraction / scattering method particle size distribution measuring device (manufactured by Beckman Coulter, trade name: LS-13 320). At this time, 1.33 was used as the refractive index of water, and 1.7 was used as the refractive index of the boron nitride particles. From the measurement results, the average particle size was calculated as a particle size (median diameter, d50) of 50% of the cumulative value of the cumulative particle size distribution. The average particle size of the obtained boron nitride particles was 510 nm.
  • Example 1 After the second step of Example 1, the boron nitride particles were placed in a boron nitride crucible and heated in an induction heating furnace at 2000 ° C. for 5 hours in the same manner as in Example 1. Boron nitride particles for comparison were obtained.
  • FIG. 8 shows a TEM image of the obtained comparative boron nitride particles obtained by the same equipment and conditions as in Example 1.
  • FIG. 8A is a TEM image of the entire comparative boron nitride particles observed at a magnification of 100,000
  • FIG. 8B is a TEM image of the periphery of the comparative boron nitride particles observed at a magnification of 400,000. It is a statue.
  • the boron nitride particles had a polygonal planar shape. Further, as can be seen from FIG. 8B, the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles was substantially flat (no unevenness within the range of 10 nm ⁇ 10 nm was observed). ..
  • the viscosities of the boron nitride particles obtained in Example 1 and the comparative boron nitride particles obtained in Comparative Example 1 were measured as a resin composition according to the following procedure.
  • a resin composition was prepared by mixing 86 parts by volume of an epoxy resin (manufactured by DIC Corporation, trade name "HP-4032D") and 14 parts by volume of boron nitride particles.
  • the obtained resin composition has a viscosity of a rheometer (“MCR92” manufactured by Anton Pearl Co., Ltd., using a parallel plate of ⁇ 25 mm as an upper jig, at a temperature of 40 ° C. and a shear rate of 0.01 to 100 s- 1.
  • MCR92 manufactured by Anton Pearl Co., Ltd.

Abstract

An aspect of the present invention pertains to a method for producing boron nitride particles, the method comprising: a first step for reacting boric acid ester with ammonia at 750-1400°C to obtain a precursor of boron nitride particles; and a second step for heating the precursor at 1000-1600°C to obtain boron nitride particles, but not comprising a step for heating the boron nitride particles above 1800°C after the second step.

Description

窒化ホウ素粒子及びその製造方法、並びに、該窒化ホウ素粒子を含む樹脂組成物及び収容体Boron nitride particles and a method for producing the same, and a resin composition and an inclusion body containing the boron nitride particles.
　本開示は、窒化ホウ素粒子及びその製造方法、並びに、該窒化ホウ素粒子を含む樹脂組成物及び収容体に関する。 The present disclosure relates to boron nitride particles and a method for producing the same, and a resin composition and an inclusion body containing the boron nitride particles.
　パワーデバイス、トランジスタ、サイリスタ、ＣＰＵ等の電子部品においては、使用時に発生する熱を効率的に放熱するための放熱部材が用いられる。放熱部材は、例えば、熱伝導率が高いセラミックス粒子を含有する。セラミックス粒子としては、高熱伝導率、高絶縁性、低比誘電率等の特性を有している窒化ホウ素粒子が注目されている。 In electronic components such as power devices, transistors, thyristors, and CPUs, heat dissipation members are used to efficiently dissipate heat generated during use. The heat radiating member contains, for example, ceramic particles having high thermal conductivity. As ceramic particles, boron nitride particles having characteristics such as high thermal conductivity, high insulation, and low relative permittivity are attracting attention.
　例えば、窒化ホウ素粒子が電子部品を一次封止する際の充填材として用いられる場合、電子部品周辺の狭い隙間にも窒化ホウ素粒子が入り込めるように、比較的小さな粒子径を有する窒化ホウ素粒子が好適である。例えば特許文献１には、平均粒子径０．０１～１．０μｍ、配向性指数１～１５、窒化ホウ素純度９８．０質量％以上、及び平均円形度０．８０以上であることを特徴とする球状窒化ホウ素微粒子、及びその製造方法が開示されている。 For example, when boron nitride particles are used as a filler for primary sealing an electronic component, boron nitride particles having a relatively small particle diameter are preferable so that the boron nitride particles can enter even in a narrow gap around the electronic component. Is. For example, Patent Document 1 is characterized by having an average particle size of 0.01 to 1.0 μm, an orientation index of 1 to 15, a boron nitride purity of 98.0% by mass or more, and an average circularity of 0.80 or more. Spherical boron nitride fine particles and a method for producing the same are disclosed.
　特許文献１に開示された製造方法は、アンモニア／ホウ酸アルコキシドのモル比が１～１０のホウ酸アルコキシドとアンモニアを不活性ガス気流中、７５０℃以上、３０秒以内で反応させた後、アンモニアガス、又は、アンモニアガスと不活性ガスの混合ガスの雰囲気下、１，０００～１，６００℃、１時間以上で熱処理後、さらに、不活性ガス雰囲気下、１，８００～２，２００℃、０．５時間以上で焼成する製造方法である。 In the production method disclosed in Patent Document 1, a borate alkoxide having a molar ratio of ammonia / borate alkoxide of 1 to 10 and ammonia are reacted in an inert gas stream at 750 ° C. or higher and within 30 seconds, and then ammonia. After heat treatment at 1,000 to 1,600 ° C. for 1 hour or more under the atmosphere of gas or a mixed gas of ammonia gas and inert gas, and further under the atmosphere of inert gas, 1,800 to 2,200 ° C. It is a manufacturing method of firing in 0.5 hours or more.
国際公開第２０１５／１２２３７９号International Publication No. 2015/122379
　窒化ホウ素粒子が、上述したように電子部品を一次封止する際の充填材に利用される場合、通常、樹脂と共に混合されて樹脂組成物の形態で用いられるが、取扱い性の観点から、当該樹脂組成物の粘度をできる限り低くすることが望ましい。 When the boron nitride particles are used as a filler for primary sealing of electronic components as described above, they are usually mixed with a resin and used in the form of a resin composition. It is desirable to make the viscosity of the resin composition as low as possible.
　そこで、本発明の一側面は、低粘度の樹脂組成物を形成可能な窒化ホウ素粒子を製造することを目的とする。 Therefore, one aspect of the present invention is to produce boron nitride particles capable of forming a low-viscosity resin composition.
　上述したように、特許文献１に記載されている製造方法では、条件を変えながら少なくとも三段階に分けて加熱が行われるが、本発明者らが鋭意検討したところ、三段階目の加熱工程を省略することにより、驚くべきことに、低粘度の樹脂組成物を形成可能な窒化ホウ素粒子が得られることを見出した。 As described above, in the production method described in Patent Document 1, heating is performed in at least three stages while changing the conditions. However, as a result of diligent studies by the present inventors, the third stage heating step is performed. It has been surprisingly found that by omitting it, boron nitride particles capable of forming a low-viscosity resin composition can be obtained.
　本発明の一側面は、ホウ酸エステルとアンモニアとを７５０～１４００℃で反応させて窒化ホウ素粒子の前駆体を得る第１の工程と、前駆体を１０００～１６００℃で加熱して窒化ホウ素粒子を得る第２の工程と、を備え、第２の工程の後に窒化ホウ素粒子を１８００℃以上で加熱する工程を備えない、窒化ホウ素粒子の製造方法である。 One aspect of the present invention is a first step of reacting boric acid ester and ammonia at 750 to 1400 ° C. to obtain a precursor of boron nitride particles, and heating the precursor at 1000 to 1600 ° C. to obtain boron nitride particles. This is a method for producing boron nitride particles, which comprises a second step of obtaining the boron nitride particles, and does not include a step of heating the boron nitride particles at 1800 ° C. or higher after the second step.
　また、本発明者らの検討によれば、上記の製造方法により得られる窒化ホウ素粒子が低粘度の樹脂組成物を形成可能である理由は、当該窒化ホウ素粒子が球形に極めて近い形状を有しているためであると推察される。 Further, according to the study by the present inventors, the reason why the boron nitride particles obtained by the above-mentioned production method can form a low-viscosity resin composition is that the boron nitride particles have a shape extremely close to a sphere. It is presumed that this is because of the fact.
　すなわち、本発明の他の一側面は、複数の窒化ホウ素結晶子を含む窒化ホウ素粒子であって、透過型電子顕微鏡により１００，０００倍の視野で観察したときに円形の平面形状を呈する、窒化ホウ素粒子である。 That is, another aspect of the present invention is boron nitride particles containing a plurality of boron nitride crystallites, which exhibit a circular planar shape when observed with a transmission electron microscope in a field of view of 100,000 times. It is a boron particle.
　窒化ホウ素粒子の平均粒子径は、１μｍ以下であってよい。窒化ホウ素粒子の平均円形度は、０．８以上であってよい。 The average particle size of the boron nitride particles may be 1 μm or less. The average circularity of the boron nitride particles may be 0.8 or more.
　本発明の他の一側面は、樹脂と、上記の窒化ホウ素粒子と、を含有する樹脂組成物である。 Another aspect of the present invention is a resin composition containing a resin and the above-mentioned boron nitride particles.
　本発明の他の一側面は、上記の窒化ホウ素粒子と、窒化ホウ素粒子を収容する容器と、を備える収容体である。 Another aspect of the present invention is an accommodating body including the above-mentioned boron nitride particles and a container for accommodating the boron nitride particles.
　本発明の一側面によれば、低粘度の樹脂組成物を形成可能な窒化ホウ素粒子を製造することができる。 According to one aspect of the present invention, boron nitride particles capable of forming a low-viscosity resin composition can be produced.
実施例の窒化ホウ素粒子全体のＴＥＭ像である。It is a TEM image of the whole boron nitride particle of an Example. 図１における窒化ホウ素粒子を拡大したＴＥＭ像である。It is an enlarged TEM image of the boron nitride particles in FIG. 図２における窒化ホウ素粒子の領域Ｓ１についてＦＦＴ解析を行った結果を示す図及びグラフである。It is a figure and the graph which shows the result of having performed the FFT analysis about the region S1 of the boron nitride particle in FIG. 図１における窒化ホウ素粒子の周囲部Ｓの領域Ｓ２～Ｓ５についてＦＦＴ解析を行った結果を示す図である。It is a figure which shows the result of having performed FFT analysis about the region S2 to S5 of the peripheral portion S of the boron nitride particle in FIG. 1. 図１における窒化ホウ素粒子の周囲部Ｓの領域Ｓ２～Ｓ５についてＦＦＴ解析を行った結果を示すグラフである。It is a graph which shows the result of having performed FFT analysis about the region S2 to S5 of the peripheral part S of the boron nitride particle in FIG. 図１における窒化ホウ素粒子の中心部Ｃの領域Ｃ１～Ｃ４についてＦＦＴ解析を行った結果を示す図である。It is a figure which shows the result of having performed FFT analysis about the region C1 to C4 of the central portion C of the boron nitride particle in FIG. 1. 図１における窒化ホウ素粒子の中心部Ｃの領域Ｃ１～Ｃ４についてＦＦＴ解析を行った結果を示すグラフである。It is a graph which shows the result of having performed FFT analysis about the region C1 to C4 of the central portion C of the boron nitride particle in FIG. 1. 比較例の窒化ホウ素粒子を観察したＴＥＭ像である。It is a TEM image which observed the boron nitride particle of the comparative example. 実施例及び比較例における粘度の測定結果を示すグラフである。It is a graph which shows the measurement result of the viscosity in an Example and a comparative example.
　以下、本発明の実施形態について詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail.
　本発明の一実施形態は、ホウ酸エステルとアンモニアとを７５０～１４００℃で反応させて窒化ホウ素粒子の前駆体を得る第１の工程と、前駆体を１０００～１６００℃で加熱して窒化ホウ素粒子を得る第２の工程と、を備える窒化ホウ素粒子の製造方法である。 One embodiment of the present invention includes a first step of reacting boric acid ester and ammonia at 750 to 1400 ° C. to obtain a precursor of boron nitride particles, and heating the precursor at 1000 to 1600 ° C. to obtain boron nitride particles. A method for producing boron nitride particles, which comprises a second step of obtaining particles.
　第１の工程では、例えば、抵抗加熱炉内に設置された反応管（例えば石英管）を加熱して、７５０～１５００℃まで昇温する。一方、不活性ガスを液状のホウ酸エステルに通した上で反応管に導入することにより、ホウ酸エステルが反応管に導入される。他方、アンモニアガスを反応管に直接導入する。不活性ガスとしては、例えば、ヘリウム、ネオン、アルゴンなどの希ガス、及び窒素ガスが挙げられる。ホウ酸エステルは、例えばアルキルホウ酸エステルであってよく、好ましくはホウ酸トリメチルである。 In the first step, for example, a reaction tube (for example, a quartz tube) installed in a resistance heating furnace is heated to raise the temperature to 750 to 1500 ° C. On the other hand, the boric acid ester is introduced into the reaction tube by passing the inert gas through the liquid boric acid ester and then introducing it into the reaction tube. On the other hand, ammonia gas is introduced directly into the reaction tube. Examples of the inert gas include rare gases such as helium, neon and argon, and nitrogen gas. The borate ester may be, for example, an alkyl borate ester, preferably trimethyl borate.
　ホウ酸エステルの導入量に対するアンモニアの導入量のモル比（アンモニア／ホウ酸エステル）は、例えば、１以上であってよく、１０以下であってよい。 The molar ratio of the amount of ammonia introduced to the amount of boric acid introduced (ammonia / boric acid ester) may be, for example, 1 or more and 10 or less.
　導入されたホウ酸エステル及びアンモニアは、加熱された反応管内で反応し、窒化ホウ素粒子の前駆体を生成する。この前駆体は、例えば、非結晶性又は低結晶性の窒化ホウ素を含んでおり、白色の粉末であってよい。生成した前駆体の一部は反応管内に付着するが、前駆体の多くは、不活性ガスや未反応のアンモニアガスにより、反応管の先に取り付けられた回収容器に送られて回収される。 The introduced boric acid ester and ammonia react in a heated reaction tube to produce a precursor of boron nitride particles. The precursor contains, for example, amorphous or low crystalline boron nitride and may be a white powder. A part of the generated precursor adheres to the inside of the reaction tube, but most of the precursor is sent to the recovery container attached to the tip of the reaction tube by the inert gas or unreacted ammonia gas and recovered.
　第１の工程においてホウ酸エステルとアンモニアとを反応させる時間（反応時間）は、好ましくは、３０秒間以内である。反応時間は、ホウ酸エステル及びアンモニアが、反応管のうち７５０～１４００℃に加熱された部分（加熱部分）にとどまる時間であり、ホウ酸エステル及びアンモニアを導入する際のガス流量と、抵抗加熱炉内に設置された反応管の長さ（反応管の加熱部分の長さ）とによって、調整することができる。 The time (reaction time) for reacting the boric acid ester with ammonia in the first step is preferably within 30 seconds. The reaction time is the time during which the boric acid ester and ammonia stay in the portion of the reaction tube heated to 750 to 1400 ° C. (heated portion), and the gas flow rate when introducing the boric acid ester and ammonia and resistance heating. It can be adjusted by the length of the reaction tube installed in the furnace (the length of the heated portion of the reaction tube).
　第２の工程では、第１の工程で得られた前駆体を、抵抗加熱炉内に設置された別の反応管（例えばアルミナ管）に入れ、窒素ガス及びアンモニアガスをそれぞれ別々に反応管内に導入する。このとき導入するガスは、アンモニアガスのみであってもよい。窒素ガス及びアンモニアガスの流量は、それぞれ、反応時間が所望の値となるように適宜調整されればよい。例えば、アンモニアガスの流量が多いほど、反応時間が短くなる。 In the second step, the precursor obtained in the first step is placed in another reaction tube (for example, an alumina tube) installed in the resistance heating furnace, and nitrogen gas and ammonia gas are separately placed in the reaction tube. Introduce. The gas introduced at this time may be only ammonia gas. The flow rates of nitrogen gas and ammonia gas may be appropriately adjusted so that the reaction time becomes a desired value, respectively. For example, the higher the flow rate of ammonia gas, the shorter the reaction time.
　続いて、反応管を１０００～１６００℃に加熱する。加熱する時間は、例えば、１時間以上であってよく、１０時間以下であってよい。これにより、前駆体中の窒化ホウ素の結晶化を進行させ、窒化ホウ素粒子を得る。ただし、前駆体中のすべての窒化ホウ素は結晶化されずに、低結晶性の窒化ホウ素が窒化ホウ素粒子の内部に残留する。 Subsequently, the reaction tube is heated to 1000 to 1600 ° C. The heating time may be, for example, 1 hour or more and 10 hours or less. As a result, the crystallization of boron nitride in the precursor is promoted to obtain boron nitride particles. However, all the boron nitride in the precursor is not crystallized, and low crystalline boron nitride remains inside the boron nitride particles.
　この製造方法は、第２の工程の後に、第２の工程で得られた窒化ホウ素粒子を１８００℃以上で加熱する工程を備えていない。すなわち、この製造方法では、上述した特許文献１に開示されているような三段階目の加熱を行わずに、目的とする窒化ホウ素粒子が得られる。この製造方法は、第２の工程の後に、第２の工程で得られた窒化ホウ素粒子を、１７００℃以上、１６００℃以上、１５００℃以上、１４００℃以上、１３００℃以上、１２００℃以上、１１００℃以上、１０００℃以上、９００℃以上、８００℃以上、７００℃以上、６００℃以上、５００℃以上、４００℃以上、３００℃以上、２００℃以上、１００℃以上、５０℃以上、４０℃以上、又は３０℃以上で加熱する工程を備えていなくてもよい。 This manufacturing method does not include a step of heating the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. That is, in this production method, the desired boron nitride particles can be obtained without performing the third stage heating as disclosed in Patent Document 1 described above. In this production method, after the second step, the boron nitride particles obtained in the second step are subjected to 1700 ° C. or higher, 1600 ° C. or higher, 1500 ° C. or higher, 1400 ° C. or higher, 1300 ° C. or higher, 1200 ° C. or higher, 1100. ℃ or more, 1000 ℃ or more, 900 ℃ or more, 800 ℃ or more, 700 ℃ or more, 600 ℃ or more, 500 ℃ or more, 400 ℃ or more, 300 ℃ or more, 200 ℃ or more, 100 ℃ or more, 50 ℃ or more, 40 ℃ or more Or, it does not have to be provided with a step of heating at 30 ° C. or higher.
　以上説明した製造方法により得られる窒化ホウ素粒子は、従来に比べてより球形に近い形状を有している。本発明の他の一実施形態は、透過型電子顕微鏡により１００，０００倍の視野で観察したときに円形の平面形状を呈する、窒化ホウ素粒子である。当該観察は、透過型電子顕微鏡（例えば、日本電子株式会社製「ＪＥＭ－２１００」）を用い、以下の条件で行われる。
　　対物レンズ絞り：φ１２０μｍ
　　集束レンズ絞り：φ１５０μｍ
　　記録媒体：ＡＭＥＴＥＫ社製「ＯｒｉｓｕｓＳＣ１０００Ａ１」
　　Ｂｉｎｉｎｇ：２
　　露光時間：０．５秒間 The boron nitride particles obtained by the production method described above have a shape closer to a sphere than the conventional one. Another embodiment of the present invention is a boron nitride particle that exhibits a circular planar shape when observed with a transmission electron microscope in a field of view of 100,000 times. The observation is performed using a transmission electron microscope (for example, "JEM-2100" manufactured by JEOL Ltd.) under the following conditions.
Objective lens aperture: φ120 μm
Condenser lens aperture: φ150 μm
Recording medium: "Orisus SC1000A1" manufactured by AMETEK
Bining: 2
Exposure time: 0.5 seconds
　窒化ホウ素粒子がこのような形状を有するのは、上述した製造方法が、第２の工程の後に、第２の工程で得られた窒化ホウ素粒子を１８００℃以上で加熱する工程を備えていないことに起因すると考えられる。なお、後述する比較例で示されるように、第２の工程で得られた窒化ホウ素粒子を１８００℃以上で加熱する工程を備える従来の方法では、上記の条件で観察したときに円形の平面形状を呈さない窒化ホウ素粒子が得られる。 The reason why the boron nitride particles have such a shape is that the above-mentioned production method does not include a step of heating the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. It is thought that this is due to. As shown in the comparative example described later, in the conventional method including a step of heating the boron nitride particles obtained in the second step at 1800 ° C. or higher, a circular planar shape is formed when observed under the above conditions. Boron nitride particles that do not exhibit the above can be obtained.
　この窒化ホウ素粒子は、例えば、低結晶性の窒化ホウ素を含む中心部と、中心部の周りを囲うように配置された、高結晶性の窒化ホウ素を含む周囲部と、を備えている。このような中心部及び周囲部において生じ得る結晶性の違いは、上述した製造方法が、第２の工程の後に、第２の工程で得られた窒化ホウ素粒子を１８００℃以上で加熱する工程を備えていないことに起因すると考えられる。 The boron nitride particles include, for example, a central portion containing low-crystalline boron nitride and a peripheral portion containing highly crystalline boron nitride arranged so as to surround the central portion. The difference in crystallinity that can occur between the central portion and the peripheral portion is that the above-mentioned production method involves heating the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. It is thought that this is due to not having it.
　本明細書において、「高結晶性」とは、以下の方法により取得される窒化ホウ素粒子のＦＦＴ像において、逆格子空間上の１～４ｎｍ－１の範囲で、ｈ－ＢＮ（０００２）面由来の周期性による輝点（ピーク）が存在する状態を意味し、「低結晶性」とは、当該輝点（ピーク）が存在しない状態を意味する。輝点（ピーク）が存在するとは、上記逆格子空間上の１～４ｎｍ－１の範囲において、Ｂ－スプライン法にてバックグラウンドを差し引いた後の強度Ｓがノイズ強度Ｎに対して１５倍以上となる点が存在することを意味する。ここで、ノイズ強度Ｎは、Ｂ－スプライン法にてバックグラウンド処理を行った後、上記逆格子空間上の４ｎｍ－１を超え６ｎｍ－１以下の範囲における標準偏差の値と定義される。また、輝点（ピーク）には、波数方向又は円周方向に揺らぎをもつものも含むこととする。高結晶性の窒化ホウ素を含む周囲部では、上記逆格子空間上の１～４ｎｍ－１の範囲において、上記強度Ｓが上記ノイズ強度Ｎに対して、好ましくは２０倍以上、より好ましくは２３倍以上、更に好ましくは２５倍以上となる点が存在してよい。 In the present specification, "high crystallinity" is derived from the h-BN (0002) plane in the range of 1 to 4 nm -1 on the reciprocal lattice space in the FFT image of the boron nitride particles obtained by the following method. It means a state in which a bright spot (peak) is present due to the periodicity of the above, and “low crystallinity” means a state in which the bright spot (peak) does not exist. The existence of a bright spot (peak) means that the intensity S after subtracting the background by the B-spline method in the range of 1 to 4 nm -1 on the reciprocal lattice space is 15 times or more the noise intensity N. It means that there is a point that becomes. Here, the noise intensity N is defined as the value of the standard deviation in the range of more than 4 nm -1 and 6 nm -1 or less on the reciprocal lattice space after performing background processing by the B-spline method. In addition, the bright spots (peaks) include those having fluctuations in the wave number direction or the circumferential direction. In the peripheral portion containing highly crystalline boron nitride, the intensity S is preferably 20 times or more, more preferably 23 times the noise intensity N in the range of 1 to 4 nm -1 on the reciprocal lattice space. As mentioned above, there may be a point that is more preferably 25 times or more.
（ＦＦＴ像の取得方法）
　まず、透過型電子顕微鏡（例えば、日本電子株式会社製「ＪＥＭ－２１００」）を用いて、以下の条件にて、窒化ホウ素粒子の４００，０００倍のＴＥＭ像を取得する。
　　対物レンズ絞り：φ１２０μｍ
　　集束レンズ絞り：φ１５０μｍ
　　記録媒体：ＡＭＥＴＥＫ社製「ＯｒｉｓｕｓＳＣ１０００Ａ１」
　　Ｂｉｎｉｎｇ：２
　　露光時間：０．５秒間
また、ＴＥＭ観察及び後述するＦＦＴ解析のために、画像解析ソフト（例えば、ＡＭＥＴＥＣ社製「ＧＭＳ３」）を用いる。
　続いて、得られたＴＥＭ像における８．５５６ｎｍ角の領域に対してＦＦＴ解析を行い、２５６×２５６ピクセルのＦＦＴ像を取得する。 (FFT image acquisition method)
First, using a transmission electron microscope (for example, "JEM-2100" manufactured by JEOL Ltd.), a TEM image of 400,000 times that of boron nitride particles is obtained under the following conditions.
Objective lens aperture: φ120 μm
Condenser lens aperture: φ150 μm
Recording medium: "Orisus SC1000A1" manufactured by AMETEK
Bining: 2
Exposure time: 0.5 seconds In addition, image analysis software (for example, "GMS3" manufactured by AMETEC) is used for TEM observation and FFT analysis described later.
Subsequently, an FFT analysis is performed on a region of 8.556 nm square in the obtained TEM image, and an FFT image of 256 × 256 pixels is acquired.
　周囲部に含まれる高結晶性の窒化ホウ素は、窒化ホウ素結晶子を構成している。窒化ホウ素結晶子とは、透過型電子顕微鏡により４００，０００倍の視野で観察したときに見られる、窒化ホウ素の結晶の最小単位を意味する。当該観察は、上記「ＦＦＴ像の取得方法」と同様の透過型電子顕微鏡及び条件によって行われる。窒化ホウ素結晶子は、例えば板状を呈している。板状の窒化ホウ素結晶子は、平板状であってよく、曲板状であってもよい。周囲部では、例えば、板状の窒化ホウ素結晶子が短手方向に積層するように配置されていてよい。 Highly crystalline boron nitride contained in the peripheral part constitutes boron nitride crystallinity. The boron nitride crystallite means the smallest unit of a boron nitride crystal seen when observed with a transmission electron microscope in a field of view of 400,000 times. The observation is performed by the same transmission electron microscope and conditions as in the above-mentioned "Method for acquiring FFT image". The boron nitride crystallite has, for example, a plate shape. The plate-shaped boron nitride crystallite may be in the shape of a flat plate or may be in the shape of a curved plate. In the peripheral portion, for example, plate-shaped boron nitride crystallites may be arranged so as to be laminated in the lateral direction.
　窒化ホウ素粒子の最表面（周囲部の最表面）には、透過型電子顕微鏡により４００，０００倍の視野で観察したときに、窒化ホウ素結晶子で構成される凹凸が形成されていてよい。当該観察は、上記「ＦＦＴ像の取得方法」と同様の透過型電子顕微鏡及び条件によって行われる。より具体的には、窒化ホウ素粒子を当該視野で観察したときに、窒化ホウ素粒子の最表面（周囲部の最表面）が複数の板状窒化ホウ素結晶子で構成されており、かつ、当該複数の板状窒化ホウ素結晶子が互いに異なる方向に延びるように配置されていることにより、窒化ホウ素粒子の最表面（周囲部の最表面）が凹凸状となっていてよい。この凹凸は、上記視野における１０ｎｍ×１０ｎｍの範囲内に収まっていてよい。言い換えれば、凹凸は、上記視野における１０ｎｍ×１０ｎｍの範囲内に少なくとも一つずつの凹部及び凸部を有していてよい。このような窒化ホウ素粒子の最表面（周囲部の最表面）に生じ得る凹凸は、上述した製造方法が、第２の工程の後に、第２の工程で得られた窒化ホウ素粒子を１８００℃以上で加熱する工程を備えていないことに起因すると考えられる。 The outermost surface of the boron nitride particles (the outermost surface of the peripheral portion) may have irregularities composed of boron nitride crystallites when observed with a transmission electron microscope in a field of view of 400,000 times. The observation is performed by the same transmission electron microscope and conditions as in the above-mentioned "Method for acquiring FFT image". More specifically, when the boron nitride particles are observed in the field of view, the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles is composed of a plurality of plate-shaped boron nitride crystals, and the plurality of the boron nitride particles are formed. By arranging the plate-shaped boron nitride crystals of the above so as to extend in different directions, the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles may be uneven. The unevenness may be within the range of 10 nm × 10 nm in the above field of view. In other words, the unevenness may have at least one concave portion and one convex portion within the range of 10 nm × 10 nm in the above field of view. The unevenness that may occur on the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles is such that the above-mentioned manufacturing method uses the boron nitride particles obtained in the second step at 1800 ° C. or higher after the second step. It is considered that this is due to the fact that it does not have a process of heating with.
　窒化ホウ素粒子中の中心部の径は、窒化ホウ素粒子の粒子径をｄとしたときに、例えば、０．１ｄ以上、０．１５ｄ以上、又は０．２ｄ以上であってよく、０．６ｄ以下、０．５以下、０．４ｄ以下、０．３５ｄ以下、又は０．３ｄ以下であってよい。窒化ホウ素粒子中の中心部の径は、例えば、１ｎｍ以上、５ｎｍ以上、１０ｎｍ以上、２０ｎｍ以上、又は３０ｎｍ以上であってよく、４００ｎｍ以下、３００ｎｍ以下、２００ｎｍ以下、又は１００ｎｍ以下であってよい。窒化ホウ素粒子中の中心部の径は、上述したとおり定義される「高結晶性」の部分、すなわち、上記逆格子空間上の１～４ｎｍ－１の範囲で、ｈ－ＢＮ（０００２）面由来の周期性による輝点（ピーク）が存在する部分の径を意味する。 The diameter of the central portion of the boron nitride particles may be, for example, 0.1d or more, 0.15d or more, or 0.2d or more, and 0.6d or less, where d is the particle size of the boron nitride particles. , 0.5 or less, 0.4d or less, 0.35d or less, or 0.3d or less. The diameter of the central portion in the boron nitride particles may be, for example, 1 nm or more, 5 nm or more, 10 nm or more, 20 nm or more, or 30 nm or more, and may be 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less. The diameter of the central portion in the boron nitride particles is derived from the h-BN (0002) plane in the “highly crystalline” portion defined as described above, that is, in the range of 1 to 4 nm -1 on the reciprocal lattice space. It means the diameter of the part where the bright spot (peak) exists due to the periodicity of.
　窒化ホウ素粒子中の周囲部の厚さは、窒化ホウ素粒子の粒子径をｄとしたときに、例えば、０．３ｄ以上、０．３３ｄ以上、又は０．３５ｄ以上であってよく、０．４５ｄ以下、０．４３ｄ以下、又は０．４ｄ以下であってよい。窒化ホウ素粒子中の中心部の径は、例えば、５ｎｍ以上、１０ｎｍ以上、２０ｎｍ以上、４０ｎｍ以上、又は６０ｎｍ以上であってよく、４５０ｎｍ以下、３００ｎｍ以下、２００ｎｍ以下、又は１００ｎｍ以下であってよい。窒化ホウ素粒子中の周囲部の厚さは、上述したとおり定義される「低結晶性」の部分、すなわち、上記逆格子空間上の１～４ｎｍ－１の範囲で、ｈ－ＢＮ（０００２）面由来の周期性による輝点（ピーク）が存在しない部分の厚さを意味する。 The thickness of the peripheral portion in the boron nitride particles may be, for example, 0.3d or more, 0.33d or more, or 0.35d or more, and 0.45d or more, where d is the particle size of the boron nitride particles. Hereinafter, it may be 0.43d or less, or 0.4d or less. The diameter of the central portion in the boron nitride particles may be, for example, 5 nm or more, 10 nm or more, 20 nm or more, 40 nm or more, or 60 nm or more, and may be 450 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less. The thickness of the peripheral portion in the boron nitride particles is the h-BN (0002) plane in the “low crystallinity” portion defined as described above, that is, in the range of 1 to 4 nm -1 on the reciprocal lattice space. It means the thickness of the part where there is no bright spot (peak) due to the periodicity of origin.
　窒化ホウ素粒子の平均粒子径は、窒化ホウ素粒子と樹脂とを混合した際の粘度増加を更に抑制できる観点から、好ましくは、０．０１μｍ以上、０．０５μｍ以上、０．１μｍ以上、又は０．１５μｍ以上であり、窒化ホウ素粒子を含む放熱部材（以下、単に「放熱部材」ともいう）の絶縁破壊特性を向上させる観点から、１μｍ以下、０．８μｍ以下、０．６μｍ以下、又は０．４μｍ以下であってよい。 The average particle size of the boron nitride particles is preferably 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, or 0. 1 μm or less, 0.8 μm or less, 0.6 μm or less, or 0.4 μm from the viewpoint of improving the insulation failure characteristics of the heat radiating member (hereinafter, also simply referred to as “radiating member”) which is 15 μm or more and contains boron nitride particles. It may be:
　窒化ホウ素粒子の平均粒子径は、以下の手順により測定される。
　窒化ホウ素粒子を分散させる分散媒として蒸留水を用い、分散剤としてヘキサメタリン酸ナトリウムを用い、０．１２５質量％ヘキサメタリン酸ナトリウム水溶液を調製する。この水溶液中に０．１ｇ／８０ｍＬの比率で窒化ホウ素粒子を加え、超音波ホモジナイザー（例えば、日本精機製作所製、商品名：ＵＳ－３００Ｅ）により、ＡＭＰＬＩＴＵＤＥ（振幅）８０％にて超音波分散を１分３０秒間で１回行うことで、窒化ホウ素粒子の分散液を調製する。この分散液を６０ｒｐｍで撹拌しながら分取し、レーザー回折散乱法粒度分布測定装置（例えば、ベックマンコールター社製、商品名：ＬＳ－１３　３２０）により体積基準の粒度分布を測定する。このとき、水の屈折率として１．３３を用い、窒化ホウ素粒子の屈折率として１．７を用いる。測定結果から、累積粒度分布の累積値５０％の粒径（メジアン径、ｄ５０）として平均粒子径を算出する。なお、このように測定される平均粒子径は、窒化ホウ素粒子の一次粒子に加えて、当該一次粒子同士が凝集した粒子（二次粒子）も含む窒化ホウ素粒子の平均粒子径であると考えられる。 The average particle size of the boron nitride particles is measured by the following procedure.
Distilled water is used as a dispersion medium for dispersing the boron nitride particles, and sodium hexametaphosphate is used as a dispersant to prepare a 0.125 mass% sodium hexametaphosphate aqueous solution. Boron nitride particles are added to this aqueous solution at a ratio of 0.1 g / 80 mL, and ultrasonic dispersion is performed with an ultrasonic homogenizer (for example, manufactured by Nissei Tokyo Office, trade name: US-300E) at 80% AMPLITUDE (amplitude). A dispersion of boron nitride particles is prepared by performing this once every 1 minute and 30 seconds. This dispersion is separated while stirring at 60 rpm, and the volume-based particle size distribution is measured by a laser diffraction / scattering method particle size distribution measuring device (for example, manufactured by Beckman Coulter, trade name: LS-13 320). At this time, 1.33 is used as the refractive index of water, and 1.7 is used as the refractive index of the boron nitride particles. From the measurement results, the average particle size is calculated as a particle size (median diameter, d50) of 50% of the cumulative value of the cumulative particle size distribution. The average particle size measured in this way is considered to be the average particle size of the boron nitride particles including the primary particles of the boron nitride particles and the particles (secondary particles) in which the primary particles are aggregated. ..
　窒化ホウ素粒子の平均円形度は、放熱部材を作製する際の充填性を向上させ、放熱部材の特性（熱伝導性、誘電率など）を等方的にする観点から、好ましくは、０．８以上、０．８２以上、０．８４以上、０．８６以上、０．８８以上、０．９０以上、０．９１以上、０．９２以上、０．９３以上、又は０．９４以上であってよい。 The average circularity of the boron nitride particles is preferably 0.8 from the viewpoint of improving the filling property when manufacturing the heat radiating member and making the characteristics (thermal conductivity, dielectric constant, etc.) of the heat radiating member isotropic. 0.82 or more, 0.84 or more, 0.86 or more, 0.88 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, or 0.94 or more. good.
　窒化ホウ素粒子の平均円形度は、以下の手順で測定される。
　走査型電子顕微鏡（ＳＥＭ）を用いて撮影した窒化ホウ素粒子の像（倍率：１０，０００倍、画像解像度：１２８０×１０２４ピクセル）について、画像解析ソフト（例えば、マウンテック社製、商品名：ＭａｃＶｉｅｗ）を用いた画像解析により、窒化ホウ素粒子の投影面積（Ｓ）及び周囲長（Ｌ）を算出する。投影面積（Ｓ）及び周囲長（Ｌ）を用いて、以下に式：
　　円形度＝４πＳ／Ｌ２
に従って円形度を求める。任意に選ばれた１００個の窒化ホウ素粒子について求めた円形度の平均値を平均円形度と定義する。 The average circularity of the boron nitride particles is measured by the following procedure.
Image analysis software (for example, manufactured by Mountech, trade name: MacView) for images of boron nitride particles (magnification: 10,000 times, image resolution: 1280 x 1024 pixels) taken with a scanning electron microscope (SEM). The projected area (S) and the peripheral length (L) of the boron nitride particles are calculated by image analysis using. Using the projected area (S) and the perimeter (L), the following equation:
Circularity = 4πS / L 2
Calculate the circularity according to. The average value of the circularity obtained for 100 arbitrarily selected boron nitride particles is defined as the average circularity.
　上述した窒化ホウ素粒子は、例えば、放熱部材に好適に用いられる。窒化ホウ素粒子は、放熱部材に用いられる場合、例えば樹脂と共に混合された樹脂組成物の形態で用いられる。すなわち、本発明の他の一実施形態は、樹脂と、上記の窒化ホウ素粒子とを含有する樹脂組成物である。この樹脂組成物は、従来に比べて低粘度化が可能となっており、放熱部材として好適に用いられる。 The above-mentioned boron nitride particles are suitably used for, for example, a heat radiating member. When the boron nitride particles are used for a heat radiating member, they are used, for example, in the form of a resin composition mixed with a resin. That is, another embodiment of the present invention is a resin composition containing the resin and the above-mentioned boron nitride particles. This resin composition can have a lower viscosity than the conventional one, and is suitably used as a heat radiating member.
　上記の窒化ホウ素粒子の含有量は、樹脂組成物の全体積を基準として、樹脂組成物の熱伝導率を向上させ、優れた放熱性能が得られやすい観点から、好ましくは３０体積％以上、より好ましくは４０体積％以上であり、更に好ましくは５０体積％以上であり、成形時に空隙の発生、並びに、絶縁性及び機械強度の低下を抑制できる観点から、好ましくは８５体積％以下、より好ましくは８０体積％以下、更に好ましくは７０体積％以下である。 The content of the above-mentioned boron nitride particles is preferably 30% by volume or more, based on the total volume of the resin composition, from the viewpoint of improving the thermal conductivity of the resin composition and easily obtaining excellent heat dissipation performance. It is preferably 40% by volume or more, more preferably 50% by volume or more, and preferably 85% by volume or less, more preferably 85% by volume or less, from the viewpoint of suppressing the generation of voids during molding and the decrease in insulating property and mechanical strength. It is 80% by volume or less, more preferably 70% by volume or less.
　樹脂としては、例えば、エポキシ樹脂、シリコーン樹脂、シリコーンゴム、アクリル樹脂、フェノール樹脂、メラミン樹脂、ユリア樹脂、不飽和ポリエステル、フッ素樹脂、ポリイミド、ポリアミドイミド、ポリエーテルイミド、ポリブチレンテレフタレート、ポリエチレンテレフタレート、ポリフェニレンエーテル、ポリフェニレンスルフィド、全芳香族ポリエステル、ポリスルホン、液晶ポリマー、ポリエーテルスルホン、ポリカーボネート、マレイミド変性樹脂、ＡＢＳ（アクリロニトリル－ブタジエン－スチレン）樹脂、ＡＡＳ（アクリロニトリル－アクリルゴム・スチレン）樹脂、及びＡＥＳ（アクリロニトリル・エチレン・プロピレン・ジエンゴム－スチレン）樹脂が挙げられる。 Examples of the resin include epoxy resin, silicone resin, silicone rubber, acrylic resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide, polybutylene terephthalate, polyethylene terephthalate, and the like. Polyphenylene ether, polyphenylene sulfide, total aromatic polyester, polysulfone, liquid crystal polymer, polyether sulfone, polycarbonate, maleimide modified resin, ABS (acrylonitrile-butadiene-styrene) resin, AAS (acrylonitrile-acrylic rubber / styrene) resin, and AES (Acrylonitrile-acrylic rubber / styrene) resin. Acrylonitrile, ethylene, propylene, diene rubber-styrene) resin can be mentioned.
　樹脂の含有量は、樹脂組成物の全体積を基準として、１５体積％以上、２０体積％以上、又は３０体積％以上であってよく、７０体積％以下、６０体積％以下、又は５０体積％以下であってよい。 The content of the resin may be 15% by volume or more, 20% by volume or more, or 30% by volume or more, based on the total volume of the resin composition, and is 70% by volume or less, 60% by volume or less, or 50% by volume. It may be:
　樹脂組成物は、樹脂を硬化させる硬化剤を更に含有していてよい。硬化剤は、樹脂の種類によって適宜選択される。例えば、樹脂がエポキシ樹脂である場合、硬化剤としては、フェノールノボラック化合物、酸無水物、アミノ化合物、及びイミダゾール化合物が挙げられる。硬化剤の含有量は、樹脂１００質量部に対して、例えば、０．５質量部以上又は１．０質量部以上であってよく、１５質量部以下又は１０質量部以下であってよい。 The resin composition may further contain a curing agent that cures the resin. The curing agent is appropriately selected depending on the type of resin. For example, when the resin is an epoxy resin, examples of the curing agent include phenol novolac compounds, acid anhydrides, amino compounds, and imidazole compounds. The content of the curing agent may be, for example, 0.5 parts by mass or more or 1.0 part by mass or more, and may be 15 parts by mass or less or 10 parts by mass or less with respect to 100 parts by mass of the resin.
　上述した窒化ホウ素粒子は、例えば、容器に収容された形態で流通し得る。すなわち、本発明の他の一実施形態は、上記の窒化ホウ素粒子と、窒化ホウ素粒子を収容する容器と、を備える収容体である。容器は、窒化ホウ素粒子を収容できる形状を有していればよく、例えば、袋、箱、瓶、缶等であってよい。 The above-mentioned boron nitride particles can be distributed, for example, in a form housed in a container. That is, another embodiment of the present invention is an accommodating body including the above-mentioned boron nitride particles and a container for accommodating the boron nitride particles. The container may have a shape capable of accommodating boron nitride particles, and may be, for example, a bag, a box, a bottle, a can, or the like.
　以下、実施例により本発明をより具体的に説明する。ただし、本発明は下記の実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples.
［実施例１］
（窒化ホウ素粒子の作製）
　まず、第１の工程では、抵抗加熱炉内に設置された反応管（石英管）を加熱して、１１５０℃まで昇温した。一方、窒素ガスをホウ酸トリメチルに通した上で反応管に導入することにより、ホウ酸トリメチルを反応管に導入した。他方、アンモニアガスを反応管に直接導入した。ホウ酸トリメチルの導入量に対するアンモニアの導入量のモル比（アンモニア／ホウ酸トリメチル）は、４．５とした。これにより、ホウ酸トリメチルとアンモニアとを反応させて、窒化ホウ素粒子の前駆体（白色粉末）を得た。なお、反応時間は１０秒間であった。 [Example 1]
(Preparation of boron nitride particles)
First, in the first step, the reaction tube (quartz tube) installed in the resistance heating furnace was heated to raise the temperature to 1150 ° C. On the other hand, trimethyl borate was introduced into the reaction tube by passing nitrogen gas through trimethyl borate and then introducing it into the reaction tube. On the other hand, ammonia gas was introduced directly into the reaction tube. The molar ratio of the amount of ammonia introduced to the amount of trimethyl borate introduced (ammonia / trimethyl borate) was 4.5. As a result, trimethyl borate was reacted with ammonia to obtain a precursor (white powder) of boron nitride particles. The reaction time was 10 seconds.
　続いて、第２の工程では、第１の工程で得られた前駆体を、抵抗加熱炉内に設置された別の反応管（アルミナ管）に入れ、窒素ガス１０Ｌ／分、及びアンモニアガス１５Ｌ／分の流量でそれぞれ別々に反応管内に導入した。そして、反応管を１５００℃で２．５時間加熱した。これにより、窒化ホウ素粒子を得た。 Subsequently, in the second step, the precursor obtained in the first step is placed in another reaction tube (alumina tube) installed in the resistance heating furnace, and nitrogen gas 10 L / min and ammonia gas 15 L. Each was introduced into the reaction tube separately at a flow rate of / min. Then, the reaction tube was heated at 1500 ° C. for 2.5 hours. As a result, boron nitride particles were obtained.
（窒化ホウ素粒子の観察及び結晶性の評価）
　透過型電子顕微鏡（ＴＥＭ；日本電子株式会社製「ＪＥＭ－２１００」）を用いて、以下の条件にて得られた窒化ホウ素粒子を観察した。
　　対物レンズ絞り：φ１２０μｍ
　　集束レンズ絞り：φ１５０μｍ
　　記録媒体：ＡＭＥＴＥＫ社製「ＯｒｉｓｕｓＳＣ１０００Ａ１」
　　Ｂｉｎｉｎｇ：２
　　露光時間：０．５秒間
また、ＴＥＭ観察及び後述するＦＦＴ解析のための画像解析ソフトとして、ＡＭＥＴＥＫ社製「ＧＭＳ３」を用いた。 (Observation of boron nitride particles and evaluation of crystallinity)
Boron nitride particles obtained under the following conditions were observed using a transmission electron microscope (TEM; "JEM-2100" manufactured by JEOL Ltd.).
Objective lens aperture: φ120 μm
Condenser lens aperture: φ150 μm
Recording medium: "Orisus SC1000A1" manufactured by AMETEK
Bining: 2
Exposure time: 0.5 seconds In addition, "GMS3" manufactured by AMETEK, Inc. was used as image analysis software for TEM observation and FFT analysis described later.
　得られた窒化ホウ素粒子全体のＴＥＭ明視野像（倍率：１００，０００倍）を図１に示す。また、図１に示される窒化ホウ素粒子のうち一粒子を拡大した像を図２（ａ）に、図２（ａ）に示される窒化ホウ素粒子の周囲部Ｓについて、４００，０００倍で観察したＴＥＭ暗視野像を図２（ｂ）にそれぞれ示す。 FIG. 1 shows a TEM bright-field image (magnification: 100,000 times) of the obtained boron nitride particles as a whole. Further, an enlarged image of one of the boron nitride particles shown in FIG. 1 was observed in FIG. 2 (a) at a magnification of 400,000 with respect to the peripheral portion S of the boron nitride particles shown in FIG. 2 (a). TEM dark-field images are shown in FIG. 2 (b), respectively.
　図１から分かるとおり、窒化ホウ素粒子は円形の平面形状を呈していた。また、図２（ｂ）から分かるとおり、窒化ホウ素粒子の最表面（周囲部の最表面）は複数の板状窒化ホウ素結晶子で構成されており、かつ、当該複数の板状窒化ホウ素結晶子が互いに異なる方向に延びるように配置されていることにより、窒化ホウ素粒子の最表面（周囲部の最表面）が凹凸状となっていた。この凹凸は、１０ｎｍ×１０ｎｍの範囲内に収まっていた。 As can be seen from FIG. 1, the boron nitride particles had a circular planar shape. Further, as can be seen from FIG. 2B, the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles is composed of a plurality of plate-shaped boron nitride crystals, and the plurality of plate-shaped boron nitride crystals. The outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles was uneven because the particles were arranged so as to extend in different directions. This unevenness was within the range of 10 nm × 10 nm.
　続いて、図２（ｂ）における８．５５６ｎｍ角の領域Ｓ１に対してＦＦＴ解析を行い、２５６×２５６ピクセルのＦＦＴ像を取得した。得られたＦＦＴ図形について、図３（ａ），（ｂ）に示すように、逆格子空間上の１～４ｎｍ－１の範囲で、ｈ－ＢＮ（０００２）面由来の周期性による輝点（ピーク）が確認された。つまり、窒化ホウ素粒子の周囲部Ｓにおける領域Ｓ１は、高結晶性の窒化ホウ素で構成されていることが確認された。 Subsequently, FFT analysis was performed on the 8.556 nm square region S1 in FIG. 2B, and an FFT image of 256 × 256 pixels was obtained. With respect to the obtained FFT figure, as shown in FIGS. 3 (a) and 3 (b), a bright spot due to periodicity derived from the h-BN (0002) plane in the range of 1 to 4 nm -1 on the reciprocal lattice space Peak) was confirmed. That is, it was confirmed that the region S1 in the peripheral portion S of the boron nitride particles was composed of highly crystalline boron nitride.
　また、図４に示すように、窒化ホウ素粒子の周囲部Ｓにおける他の領域Ｓ２～Ｓ５についても、領域Ｓ１と同様にしてＦＦＴ解析を行った。その結果、図４及び図５に示すように、逆格子空間上の１～４ｎｍ－１の範囲で、ｈ－ＢＮ（０００２）面由来の周期性による輝点（ピーク）が確認された。つまり、窒化ホウ素粒子の周囲部Ｓにおける領域Ｓ２～Ｓ５も、高結晶性の窒化ホウ素で構成されていることが確認された。 Further, as shown in FIG. 4, FFT analysis was performed on the other regions S2 to S5 in the peripheral portion S of the boron nitride particles in the same manner as in the region S1. As a result, as shown in FIGS. 4 and 5, bright spots (peaks) due to periodicity derived from the h-BN (0002) plane were confirmed in the range of 1 to 4 nm -1 on the reciprocal lattice space. That is, it was confirmed that the regions S2 to S5 in the peripheral portion S of the boron nitride particles were also composed of highly crystalline boron nitride.
　また、図１に示される窒化ホウ素粒子の中心部Ｃについて、４００，０００倍で観察したＴＥＭ暗視野像を図６に示す。図６に示すように、窒化ホウ素粒子の中心部Ｃにおける他の領域Ｃ１～Ｃ４についても、領域Ｓ１と同様にしてＦＦＴ解析を行った。その結果、図６及び図７に示すように、逆格子空間上の１～４ｎｍ－１の範囲で、ｈ－ＢＮ（０００２）面由来の周期性による輝点（ピーク）が確認されなかった。つまり、窒化ホウ素粒子の中心部Ｃにおける領域Ｃ１～Ｃ４は、低結晶性の窒化ホウ素で構成されていることが確認された。 Further, FIG. 6 shows a TEM dark-field image of the central portion C of the boron nitride particles shown in FIG. 1 observed at a magnification of 400,000. As shown in FIG. 6, FFT analysis was performed on the other regions C1 to C4 in the central portion C of the boron nitride particles in the same manner as in the region S1. As a result, as shown in FIGS. 6 and 7, no bright spot (peak) due to periodicity derived from the h-BN (0002) plane was confirmed in the range of 1 to 4 nm -1 on the reciprocal lattice space. That is, it was confirmed that the regions C1 to C4 in the central portion C of the boron nitride particles are composed of low crystallinity boron nitride.
　なお、図３（ｂ）、図５及び図７に示すグラフは、Ｂ－スプライン法にてバックグラウンドを差し引いた後の強度を示すグラフである。また、図３（ｂ）図５及び図７に示すグラフより、領域Ｓ１～Ｓ５及びＣ１～Ｃ４の各領域について、逆格子空間上の１～４ｎｍ－１の範囲における最大強度（相対強度）Ｓｍａｘと、ノイズ強度（逆格子空間上の４ｎｍ－１を超え６ｎｍ－１以下の範囲における標準偏差）Ｎと、これらの比（Ｓｍａｘ／Ｎ）とを求めた。結果を表１に示す。 The graphs shown in FIGS. 3 (b), 5 and 7 are graphs showing the intensity after subtracting the background by the B-spline method. Further, from the graphs shown in FIGS. 5 and 7 of FIG. 3B, the maximum intensity (relative intensity) Smax in the range of 1 to 4 nm -1 on the reciprocal lattice space for each of the regions S1 to S5 and C1 to C4. The noise intensity (standard deviation in the range of more than 4 nm -1 and 6 nm -1 or less on the reciprocal lattice space) N and their ratio (Smax / N) were obtained. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　以上のとおり、得られた窒化ホウ素粒子の周囲部には高結晶性の窒化ホウ素が含まれており（上述した輝点（ピーク）が確認できる領域が支配的であり）、中心部には低結晶性の窒化ホウ素が含まれている（上述した輝点（ピーク）が確認できない領域が支配的である）ことが分かった。また、中心部の径は約４０ｎｍであり、周囲部の厚さは約５０ｎｍであった。 As described above, the obtained boron nitride particles contain highly crystalline boron nitride in the peripheral portion (the region where the above-mentioned bright spot (peak) can be confirmed is dominant), and the central portion is low. It was found that crystalline boron nitride was contained (the region where the above-mentioned bright spot (peak) could not be confirmed was dominant). The diameter of the central portion was about 40 nm, and the thickness of the peripheral portion was about 50 nm.
（平均円形度の測定）
　まず、走査型電子顕微鏡（ＳＥＭ）を用いて撮影した窒化ホウ素粒子の像（倍率：１０，０００倍、画像解像度：１２８０×１０２４ピクセル）について、画像解析ソフト（例えば、マウンテック社製、商品名：ＭａｃＶｉｅｗ）を用いた画像解析により、窒化ホウ素粒子の投影面積（Ｓ）及び周囲長（Ｌ）を算出した。次に、投影面積（Ｓ）及び周囲長（Ｌ）を用いて、以下に式：
　　円形度＝４πＳ／Ｌ２
に従って円形度を求めた。任意に選ばれた１００個の窒化ホウ素粒子について求めた円形度の平均値を平均円形度として算出した。得られた窒化ホウ素粒子の平均円形度は、０．９４であった。 (Measurement of average circularity)
First, for an image of boron nitride particles (magnification: 10,000 times, image resolution: 1280 x 1024 pixels) taken with a scanning electron microscope (SEM), image analysis software (for example, manufactured by Mountech Co., Ltd., trade name: The projected area (S) and peripheral length (L) of the boron nitride particles were calculated by image analysis using a MacView). Next, using the projected area (S) and the perimeter (L), the following equation:
Circularity = 4πS / L 2
The circularity was calculated according to. The average value of the circularity obtained for 100 arbitrarily selected boron nitride particles was calculated as the average circularity. The average circularity of the obtained boron nitride particles was 0.94.
（平均粒子径の測定）
　窒化ホウ素粒子を分散させる分散媒として蒸留水を用い、分散剤としてヘキサメタリン酸ナトリウムを用い、０．１２５質量％ヘキサメタリン酸ナトリウム水溶液を調製した。この水溶液中に０．１ｇ／８０ｍＬの比率で窒化ホウ素粒子を加え、超音波ホモジナイザー（日本精機製作所製、商品名：ＵＳ－３００Ｅを使用）により、ＡＭＰＬＩＴＵＤＥ（振幅）８０％にて超音波分散を１分３０秒間で１回行うことで、窒化ホウ素粒子の分散液を調製した。この分散液を６０ｒｐｍで撹拌しながら分取し、レーザー回折散乱法粒度分布測定装置（ベックマンコールター社製、商品名：ＬＳ－１３　３２０）により体積基準の粒度分布を測定した。このとき、水の屈折率として１．３３を用い、窒化ホウ素粒子の屈折率として１．７を用いた。測定結果から、累積粒度分布の累積値５０％の粒径（メジアン径、ｄ５０）として平均粒子径を算出した。得られた窒化ホウ素粒子の平均粒子径は、５１０ｎｍであった。 (Measurement of average particle size)
Distilled water was used as a dispersion medium for dispersing the boron nitride particles, and sodium hexametaphosphate was used as a dispersant to prepare a 0.125 mass% sodium hexametaphosphate aqueous solution. Boron nitride particles are added to this aqueous solution at a ratio of 0.1 g / 80 mL, and ultrasonic dispersion is performed with an ultrasonic homogenizer (manufactured by Nissei Tokyo Office, trade name: US-300E) at 80% AMPLITUDE (amplitude). A dispersion of boron nitride particles was prepared by performing this once every 1 minute and 30 seconds. This dispersion was separated while stirring at 60 rpm, and the volume-based particle size distribution was measured with a laser diffraction / scattering method particle size distribution measuring device (manufactured by Beckman Coulter, trade name: LS-13 320). At this time, 1.33 was used as the refractive index of water, and 1.7 was used as the refractive index of the boron nitride particles. From the measurement results, the average particle size was calculated as a particle size (median diameter, d50) of 50% of the cumulative value of the cumulative particle size distribution. The average particle size of the obtained boron nitride particles was 510 nm.
［比較例１］
　実施例１の第２の工程の後に、窒化ホウ素粒子を窒化ホウ素製ルツボに入れ、誘導加熱炉において、窒素雰囲気下にて２０００℃で５時間加熱した以外は、実施例１と同様にして、比較用窒化ホウ素粒子を得た。 [Comparative Example 1]
After the second step of Example 1, the boron nitride particles were placed in a boron nitride crucible and heated in an induction heating furnace at 2000 ° C. for 5 hours in the same manner as in Example 1. Boron nitride particles for comparison were obtained.
　得られた比較用窒化ホウ素粒子について、実施例１と同じ装置及び条件により得られたＴＥＭ像を図８に示す。図８（ａ）は、１００，０００倍で観察した比較用窒化ホウ素粒子全体のＴＥＭ像であり、図８（ｂ）は、４００，０００倍で観察した比較用窒化ホウ素粒子の周囲部のＴＥＭ像である。 FIG. 8 shows a TEM image of the obtained comparative boron nitride particles obtained by the same equipment and conditions as in Example 1. FIG. 8A is a TEM image of the entire comparative boron nitride particles observed at a magnification of 100,000, and FIG. 8B is a TEM image of the periphery of the comparative boron nitride particles observed at a magnification of 400,000. It is a statue.
　図８（ａ）から分かるとおり、窒化ホウ素粒子は多角形の平面形状を呈していた。また、図８（ｂ）から分かるとおり、窒化ホウ素粒子の最表面（周囲部の最表面）は略平面状となっていた（１０ｎｍ×１０ｎｍの範囲内に収まるような凹凸は観察されなかった）。 As can be seen from FIG. 8A, the boron nitride particles had a polygonal planar shape. Further, as can be seen from FIG. 8B, the outermost surface (the outermost surface of the peripheral portion) of the boron nitride particles was substantially flat (no unevenness within the range of 10 nm × 10 nm was observed). ..
＜粘度の測定＞
　実施例１で得られた窒化ホウ素粒子、及び比較例１で得られた比較用窒化ホウ素粒子について、以下の手順で樹脂組成物としたときの粘度を測定した。
　エポキシ樹脂（ＤＩＣ社製、商品名「ＨＰ－４０３２Ｄ」）８６体積部と、窒化ホウ素粒子１４体積部とを混合して樹脂組成物を調製した。得られた樹脂組成物について、レオメータ（アントンパール社製「ＭＣＲ９２」にて、上部治具としてφ２５ｍｍのパラレルプレートを用い、温度：４０℃、せん断速度：０．０１～１００ｓ－１の条件で粘度を測定した。得られた結果を図９に示す。 <Measurement of viscosity>
The viscosities of the boron nitride particles obtained in Example 1 and the comparative boron nitride particles obtained in Comparative Example 1 were measured as a resin composition according to the following procedure.
A resin composition was prepared by mixing 86 parts by volume of an epoxy resin (manufactured by DIC Corporation, trade name "HP-4032D") and 14 parts by volume of boron nitride particles. The obtained resin composition has a viscosity of a rheometer (“MCR92” manufactured by Anton Pearl Co., Ltd., using a parallel plate of φ25 mm as an upper jig, at a temperature of 40 ° C. and a shear rate of 0.01 to 100 s- 1. The obtained results are shown in FIG.

Claims (6)

  1. 　ホウ酸エステルとアンモニアとを７５０～１４００℃で反応させて窒化ホウ素粒子の前駆体を得る第１の工程と、
    　前記前駆体を１０００～１６００℃で加熱して窒化ホウ素粒子を得る第２の工程と、を備え、
    　前記第２の工程の後に前記窒化ホウ素粒子を１８００℃以上で加熱する工程を備えない、窒化ホウ素粒子の製造方法。     The first step of reacting boric acid ester and ammonia at 750 to 1400 ° C. to obtain a precursor of boron nitride particles, and
    A second step of heating the precursor at 1000 to 1600 ° C. to obtain boron nitride particles is provided.
    A method for producing boron nitride particles, which does not include a step of heating the boron nitride particles at 1800 ° C. or higher after the second step.
  2. 　複数の窒化ホウ素結晶子を含む窒化ホウ素粒子であって、
    　透過型電子顕微鏡により１００，０００倍の視野で観察したときに円形の平面形状を呈する、窒化ホウ素粒子。     Boron nitride particles containing a plurality of boron nitride crystals.
    Boron nitride particles that exhibit a circular planar shape when observed with a transmission electron microscope in a field of view of 100,000 times.
  3. 　前記窒化ホウ素粒子の平均粒子径が１μｍ以下である、請求項２に記載の窒化ホウ素粒子。 The boron nitride particles according to claim 2, wherein the average particle size of the boron nitride particles is 1 μm or less.
  4. 　前記窒化ホウ素粒子の平均円形度が０．８以上である、請求項２又は３に記載の窒化ホウ素粒子。 The boron nitride particles according to claim 2 or 3, wherein the boron nitride particles have an average circularity of 0.8 or more.
  5. 　樹脂と、請求項２～４のいずれか一項に記載の窒化ホウ素粒子と、を含有する樹脂組成物。 A resin composition containing a resin and the boron nitride particles according to any one of claims 2 to 4.
  6. 　請求項２～４のいずれか一項に記載の窒化ホウ素粒子と、前記窒化ホウ素粒子を収容する容器と、を備える収容体。 An accommodating body including the boron nitride particles according to any one of claims 2 to 4 and a container for accommodating the boron nitride particles.
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