WO2021100808A1 - Boron nitride particles and resin composition - Google Patents

Boron nitride particles and resin composition Download PDF

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Publication number
WO2021100808A1
WO2021100808A1 PCT/JP2020/043198 JP2020043198W WO2021100808A1 WO 2021100808 A1 WO2021100808 A1 WO 2021100808A1 JP 2020043198 W JP2020043198 W JP 2020043198W WO 2021100808 A1 WO2021100808 A1 WO 2021100808A1
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Prior art keywords
boron nitride
nitride particles
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reaction tube
resin
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PCT/JP2020/043198
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French (fr)
Japanese (ja)
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祐輔 佐々木
建治 宮田
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デンカ株式会社
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Priority to JP2021558443A priority Critical patent/JPWO2021100808A1/ja
Priority to CN202080073914.4A priority patent/CN114599603A/en
Publication of WO2021100808A1 publication Critical patent/WO2021100808A1/en

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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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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
    • C08K2003/382—Boron-containing compounds and nitrogen
    • C08K2003/385—Binary compounds of nitrogen with boron

Definitions

  • the present invention relates to boron nitride particles and a resin composition.
  • a heat radiating member having high thermal conductivity is used together with such an electronic component.
  • boron nitride particles have high thermal conductivity and high insulating properties, and are therefore widely used as fillers in heat radiating members.
  • Patent Document 1 states that a boron nitride agglomerated particle composition having high thermal conductivity and very useful for a heat dissipation sheet required for a power semiconductor device or the like is nitrided having an average particle diameter (D 50 ) of 1 ⁇ m to 200 ⁇ m.
  • D 50 average particle diameter
  • heat dissipation members are also required to have characteristics that contribute to them. Specifically, a heat radiating member having a low dielectric constant and a low dielectric loss tangent is desirable.
  • an object of the present invention is to provide boron nitride particles capable of realizing a heat radiating member having a low dielectric constant and a low dielectric loss tangent.
  • One aspect of the present invention is boron nitride particles having an average particle diameter of 450 nm or more and 800 nm or less and a BET diameter of 160 nm or more and 300 nm 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.
  • boron nitride particles capable of realizing a heat radiating member having a low dielectric constant and a low dielectric loss tangent.
  • One embodiment of the present invention is boron nitride particles having a specific average particle size and BET diameter.
  • the average particle size reflects the particle size in consideration of the aggregated state of the boron nitride particles (both primary particles and secondary particles).
  • the BET diameter reflects the particle size of the primary particles of the boron nitride particles. That is, the boron nitride particles of the present embodiment have specific values for both the BET diameter with respect to the particle size of the primary particles and the average particle size considering the aggregated state (both primary particles and secondary particles). is there.
  • the average particle size of the boron nitride particles is 450 nm or more, preferably 470 nm or more, from the viewpoint of lowering the dielectric constant and the dielectric loss tangent of the heat radiating member containing the boron nitride particles (hereinafter, also simply referred to as “radiating member”). It may be 490 nm or more, 510 nm or more, or 530 nm or more.
  • the average particle size of the boron nitride particles is 800 nm or less, preferably 760 nm or less, 720 nm or less, 680 nm or less, 640 nm or less, 600 nm or less, or 560 nm or less from the viewpoint of improving the dielectric breakdown characteristics of the heat radiating member. May be good.
  • 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 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 Nippon Seiki Seisakusho Co., Ltd., trade name: US-300E) at 80% AMPLITUDE (amplitude).
  • an ultrasonic homogenizer for example, manufactured by Nippon Seiki Seisakusho Co., Ltd., 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 BET diameter of the boron nitride particles is 160 nm or more, preferably 170 nm or more, 180 nm or more, or 190 nm or more from the viewpoint of lowering the dielectric constant and the dielectric loss tangent of the heat radiating member.
  • the BET diameter of the boron nitride particles is 300 nm or less, preferably 290 nm or less, 280 nm or less, 270 nm or less, or 260 nm or less from the viewpoint of lowering the dielectric constant and the dielectric loss tangent of the heat radiating member.
  • the BET diameter of the boron nitride particles is a value calculated by the following formula.
  • the boron nitride particles are preferably spherical or spherical from the viewpoint of improving the filling property of the boron nitride particles when producing the heat radiating member and making the characteristics (thermal conductivity, dielectric constant, etc.) of the heat radiating member isotropic. It has a shape close to a sphere. From the same viewpoint, the average circularity of the boron nitride particles may be preferably 0.8 or more, 0.82 or more, 0.84 or more, 0.86 or more, or 0.88 or more.
  • 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 boron nitride particles described above have a first step of reacting borate ester and ammonia at 750 to 1400 ° C. to obtain a first precursor, and heating the first precursor at 1000 to 1600 ° C.
  • the environmental temperature at which the second precursor is placed is once lowered to room temperature (10 to 30 ° C.).
  • the boron nitride particles having the above-mentioned characteristics can be obtained by heating at 1000 to 1600 ° C., returning to room temperature, and heating again at 1000 to 1600 ° C.
  • a manufacturing method including the first step, the second step, and the fourth step is known, but in the manufacturing method of the present embodiment, as described above, the first step is described.
  • 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 first precursor (white powder).
  • a part of the generated first precursor adheres to the inside of the reaction tube, but most of the first precursor is sent to the recovery vessel attached to the tip of the reaction tube by the inert gas or unreacted ammonia gas. And be recovered.
  • the time for reacting the boric acid ester with ammonia is preferably within 30 seconds.
  • the reaction time is the time during which the borate 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 borate 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 part of the reaction tube).
  • the first precursor obtained in the first step is placed in another reaction tube (for example, an alumina tube) installed in a resistance heating furnace, and nitrogen gas and ammonia gas are separately charged. Introduce into the reaction tube.
  • 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, as the flow rate of ammonia gas increases, the reaction time tends to be short, and as a result, the average particle size of the finally obtained boron nitride particles tends to be large, and the BET diameter tends to be small.
  • 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. This gives a second precursor.
  • the power of the resistance heating furnace is turned off, the introduction of nitrogen gas and ammonia gas is stopped, and the temperature in the reaction tube is lowered to room temperature (10 to 30 ° C.), and the second precursor is used.
  • the resting time of the body may be, for example, 0.5 hours or more and 96 hours or less.
  • nitrogen gas and ammonia gas are reintroduced into the reaction tube, and the reaction tube is heated again to 1000 to 1600 ° C.
  • Examples of the flow rates of nitrogen gas and ammonia gas, and the heating time may be the same as those described in the second step.
  • the conditions of the second step and the conditions of the third step may be the same as each other or may be different from each other. This gives a third precursor.
  • the third precursor obtained in the third step is placed in a boron nitride crucible and heated to 1800 to 2200 ° C. in an induction heating furnace under a nitrogen atmosphere.
  • the heating time may be, for example, 0.5 hours or more, and may be 10 hours or less.
  • the boron nitride particles described above are suitably used for, for example, a heat radiating member.
  • a heat radiating member having a low dielectric constant and a low dielectric loss tangent can be obtained.
  • the boron nitride particles are used, for example, as 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.
  • 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, polyolefin (polyethylene, etc.), polyimide, polyamideimide, polyetherimide, and poly.
  • 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 resin composition may further contain boron nitride particles other than the above-mentioned boron nitride particles (for example, known boron nitride particles such as massive boron nitride particles formed by aggregating scaly primary particles).
  • boron nitride particles other than the above-mentioned boron nitride particles (for example, known boron nitride particles such as massive boron nitride particles formed by aggregating scaly primary particles).
  • the first precursor obtained in the first step is placed in another reaction tube (alumina tube) installed in the resistance heating furnace, and nitrogen gas and ammonia gas are charged, respectively. Separately, they were introduced into the reaction tube at the flow rates shown in Table 1. Then, the reaction tube was heated at the temperature and time shown in Table 1. This gave a second precursor.
  • alumina tube alumina tube
  • the power of the resistance heating furnace was turned off, the introduction of nitrogen gas and ammonia gas was stopped, and the temperature in the reaction tube was lowered to 25 ° C., and the second precursor was allowed to stand for 2 hours.
  • the third precursor obtained in the third step was placed in a boron nitride crucible and heated in an induction heating furnace under a nitrogen atmosphere at the temperature and time shown in Table 1. As a result, boron nitride particles were obtained.
  • 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 Nippon Seiki Seisakusho, 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 permittivity and dielectric loss tangent when each of the obtained boron nitride particles was used was measured by the following method. The results are shown in Table 1. Boron nitride particles are kneaded with polyethylene (manufactured by Japan Polyethylene Corporation, trade name "Novatec HY540") in an amount that makes the amount of boron nitride particles 20% by volume, and sheet molding is performed to obtain a 0.2 mm thick sheet. Got Kneading and sheet forming were carried out using a twin-screw extruder under the condition of a temperature of 180 ° C. Using a measuring device of the cavity resonator method, the sheet obtained under the conditions of a frequency of 36 GHz and a temperature of 25 ° C. was measured, and the dielectric constant and the dielectric loss tangent of the sheet were determined.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
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Abstract

One aspect of the present invention provides boron nitride particles having an average particle diameter of 450 to 800 nm inclusive and each having a BET diameter of 160 to 300 nm inclusive.

Description

窒化ホウ素粒子及び樹脂組成物Boron Nitride Particles and Resin Composition
　本発明は、窒化ホウ素粒子及び樹脂組成物に関する。 The present invention relates to boron nitride particles and a resin composition.
　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良く放熱することが重要な問題となっている。そのため、このような電子部品と共に、高い熱伝導性を有する放熱部材が用いられる。一方、窒化ホウ素粒子は、高熱伝導性及び高絶縁性を有しているため、放熱部材における充填材として幅広く利用されている。 In electronic components such as transistors, thyristors, and CPUs, it is an important issue to efficiently dissipate heat generated during use. Therefore, a heat radiating member having high thermal conductivity is used together with such an electronic component. On the other hand, boron nitride particles have high thermal conductivity and high insulating properties, and are therefore widely used as fillers in heat radiating members.
　例えば特許文献１には、高い熱伝導性を示しパワー半導体デバイスなどで必要とされる放熱シートに非常に有用な窒化ホウ素凝集粒子組成物として、平均粒子径（Ｄ５０）が１μｍ～２００μｍの窒化ホウ素凝集粒子の組成物であって、所定の条件を満たすことを特徴とする窒化ホウ素凝集粒子組成物が開示されている。 For example, Patent Document 1 states that a boron nitride agglomerated particle composition having high thermal conductivity and very useful for a heat dissipation sheet required for a power semiconductor device or the like is nitrided having an average particle diameter (D 50 ) of 1 μm to 200 μm. A composition of boron nitride agglomerated particles, which is characterized by satisfying a predetermined condition, is disclosed.
特開２０１７－０３６１９０号公報Japanese Unexamined Patent Publication No. 2017-036190
　近年、電子部品を搭載したデバイスでは、信号の高速伝送化や大容量化が進んでいるため、放熱部材にもそれに寄与するような特性が求められている。具体的には、低誘電率かつ低誘電正接の放熱部材が望ましい。 In recent years, devices equipped with electronic components have been increasing in speed and capacity of signals, and therefore, heat dissipation members are also required to have characteristics that contribute to them. Specifically, a heat radiating member having a low dielectric constant and a low dielectric loss tangent is desirable.
　そこで、本発明は、低誘電率かつ低誘電正接の放熱部材を実現できる窒化ホウ素粒子を提供することを目的とする。 Therefore, an object of the present invention is to provide boron nitride particles capable of realizing a heat radiating member having a low dielectric constant and a low dielectric loss tangent.
　本発明の一側面は、平均粒子径が４５０ｎｍ以上８００ｎｍ以下であり、ＢＥＴ径が１６０ｎｍ以上３００ｎｍ以下である、窒化ホウ素粒子である。 One aspect of the present invention is boron nitride particles having an average particle diameter of 450 nm or more and 800 nm or less and a BET diameter of 160 nm or more and 300 nm or less.
　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 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.
　本発明によれば、低誘電率かつ低誘電正接の放熱部材を実現できる窒化ホウ素粒子を提供することが可能となる。 According to the present invention, it is possible to provide boron nitride particles capable of realizing a heat radiating member having a low dielectric constant and a low dielectric loss tangent.
　本発明の一実施形態は、特定の平均粒子径及びＢＥＴ径を有する窒化ホウ素粒子である。なお、平均粒子径は、窒化ホウ素粒子の凝集状態（一次粒子及び二次粒子の両方）を考慮した粒子径を反映したものである。一方、ＢＥＴ径は、窒化ホウ素粒子の一次粒子の粒子径を反映したものである。つまり、本実施形態の窒化ホウ素粒子は、一次粒子の粒子径に関するＢＥＴ径と、凝集状態（一次粒子及び二次粒子の両方）を考慮した平均粒子径との両方について特定の値を有するものである。 One embodiment of the present invention is boron nitride particles having a specific average particle size and BET diameter. The average particle size reflects the particle size in consideration of the aggregated state of the boron nitride particles (both primary particles and secondary particles). On the other hand, the BET diameter reflects the particle size of the primary particles of the boron nitride particles. That is, the boron nitride particles of the present embodiment have specific values for both the BET diameter with respect to the particle size of the primary particles and the average particle size considering the aggregated state (both primary particles and secondary particles). is there.
　窒化ホウ素粒子の平均粒子径は、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）の誘電率及び誘電正接を低くする観点から、４５０ｎｍ以上であり、好ましくは、４７０ｎｍ以上、４９０ｎｍ以上、５１０ｎｍ以上、又は５３０ｎｍ以上であってもよい。窒化ホウ素粒子の平均粒子径は、放熱部材の絶縁破壊特性を向上させる観点から、８００ｎｍ以下であり、好ましくは、７６０ｎｍ以下、７２０ｎｍ以下、６８０ｎｍ以下、６４０ｎｍ以下、６００ｎｍ以下、又は５６０ｎｍ以下であってもよい。 The average particle size of the boron nitride particles is 450 nm or more, preferably 470 nm or more, from the viewpoint of lowering the dielectric constant and the dielectric loss tangent of the heat radiating member containing the boron nitride particles (hereinafter, also simply referred to as “radiating member”). It may be 490 nm or more, 510 nm or more, or 530 nm or more. The average particle size of the boron nitride particles is 800 nm or less, preferably 760 nm or less, 720 nm or less, 680 nm or less, 640 nm or less, 600 nm or less, or 560 nm or less from the viewpoint of improving the dielectric breakdown characteristics of the heat radiating member. May be good.
　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％ヘキサメタリン酸水溶液ナトリウムを調製する。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。 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 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 Nippon Seiki Seisakusho Co., Ltd., 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.
　窒化ホウ素粒子のＢＥＴ径は、放熱部材の誘電率及び誘電正接を低くする観点から、１６０ｎｍ以上であり、好ましくは、１７０ｎｍ以上、１８０ｎｍ以上、又は１９０ｎｍ以上であってもよい。窒化ホウ素粒子のＢＥＴ径は、放熱部材の誘電率及び誘電正接を低くする観点から、３００ｎｍ以下であり、好ましくは、２９０ｎｍ以下、２８０ｎｍ以下、２７０ｎｍ以下、又は２６０ｎｍ以下であってもよい。 The BET diameter of the boron nitride particles is 160 nm or more, preferably 170 nm or more, 180 nm or more, or 190 nm or more from the viewpoint of lowering the dielectric constant and the dielectric loss tangent of the heat radiating member. The BET diameter of the boron nitride particles is 300 nm or less, preferably 290 nm or less, 280 nm or less, 270 nm or less, or 260 nm or less from the viewpoint of lowering the dielectric constant and the dielectric loss tangent of the heat radiating member.
　窒化ホウ素粒子のＢＥＴ径は、下記式により算出される値である。
　　ＢＥＴ径＝窒化ホウ素１ｇで真球の１粒子となると仮定したときの直径／（ＢＥＴ比表面積／窒化ホウ素１ｇで真球の１粒子となると仮定したときの表面積）
　ここで、
・窒化ホウ素１ｇで真球の１粒子となると仮定したときの直径
　＝（６／（窒化ホウ素粒子の密度×π））１／３
　（ただし、窒化ホウ素粒子の密度として２．２６ｇ／ｃｍ３を用いる）
・窒化ホウ素１ｇで真球の１粒子となると仮定したときの表面積
　＝π×（窒化ホウ素１ｇで真球の１粒子となると仮定したときの直径）２
・ＢＥＴ比表面積
　ＪＩＳ　Ｚ　８８０３：２０１３に準拠し、窒素ガスを使用してＢＥＴ一点法により測定される窒化ホウ素粒子のＢＥＴ比表面積
である。 The BET diameter of the boron nitride particles is a value calculated by the following formula.
BET diameter = diameter when 1 g of boron nitride is assumed to be one true sphere particle / (BET specific surface area / surface area when 1 g of boron nitride is assumed to be one true sphere)
here,
-Diameter assuming that 1 g of boron nitride becomes one true sphere particle = (6 / (density of boron nitride particles x π)) 1/3
(However, 2.26 g / cm 3 is used as the density of boron nitride particles)
・ Surface area when 1 g of boron nitride is assumed to be one true sphere particle = π × (diameter when 1 g of boron nitride is assumed to be one true sphere particle) 2
BET specific surface area This is the BET specific surface area of boron nitride particles measured by the BET one-point method using nitrogen gas in accordance with JIS Z 8803: 2013.
　窒化ホウ素粒子は、放熱部材を作製する際の窒化ホウ素粒子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、球状、又は球状に近い形状を有している。同様の観点から、窒化ホウ素粒子の平均円形度は、好ましくは、０．８以上、０．８２以上、０．８４以上、０．８６以上、又は０．８８以上であってよい。 The boron nitride particles are preferably spherical or spherical from the viewpoint of improving the filling property of the boron nitride particles when producing the heat radiating member and making the characteristics (thermal conductivity, dielectric constant, etc.) of the heat radiating member isotropic. It has a shape close to a sphere. From the same viewpoint, the average circularity of the boron nitride particles may be preferably 0.8 or more, 0.82 or more, 0.84 or more, 0.86 or more, or 0.88 or more.
　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.
　以上説明した窒化ホウ素粒子は、ホウ酸エステルとアンモニアとを７５０～１４００℃で反応させて第１の前駆体を得る第１の工程と、第１の前駆体を１０００～１６００℃で加熱して第２の前駆体を得る第２の工程と、第２の前駆体を１０００～１６００℃で加熱して第３の前駆体を得る第３の工程と、第３の前駆体を１８００～２２００℃で加熱して第４の前駆体を得る第４の工程と、を備える製造方法により得られる。 The boron nitride particles described above have a first step of reacting borate ester and ammonia at 750 to 1400 ° C. to obtain a first precursor, and heating the first precursor at 1000 to 1600 ° C. The second step of obtaining the second precursor, the third step of heating the second precursor at 1000 to 1600 ° C. to obtain the third precursor, and the third step of heating the third precursor at 1800 to 2200 ° C. It is obtained by a production method comprising a fourth step of heating with and obtaining a fourth precursor.
　また、この製造方法では、第２の工程の終了後、第３の工程の開始前に、第２の前駆体が置かれる環境温度を常温（１０～３０℃）まで一旦下げる。このように、１０００～１６００℃での加熱した後、常温に戻し、再び１０００～１６００℃で加熱することにより、上述したような特性を有する窒化ホウ素粒子が得られる。一方、従来の製造方法として、例えば、上記第１の工程、第２の工程、及び第４の工程を備える製造方法は知られているが、本実施形態の製造方法では、上述したとおり、第２の工程に加えて第３の工程を実施し、かつ、第２の工程と第３の工程の間で環境温度を常温まで一旦下げることにより、従来にない特性を有する窒化ホウ素粒子を得ることができる。 Further, in this manufacturing method, after the completion of the second step and before the start of the third step, the environmental temperature at which the second precursor is placed is once lowered to room temperature (10 to 30 ° C.). As described above, the boron nitride particles having the above-mentioned characteristics can be obtained by heating at 1000 to 1600 ° C., returning to room temperature, and heating again at 1000 to 1600 ° C. On the other hand, as a conventional manufacturing method, for example, a manufacturing method including the first step, the second step, and the fourth step is known, but in the manufacturing method of the present embodiment, as described above, the first step is described. By carrying out the third step in addition to the second step and once lowering the environmental temperature to room temperature between the second step and the third step, boron nitride particles having unprecedented characteristics can be obtained. Can be done.
　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、第１の前駆体（白色粉末）が生成する。生成した第１の前駆体の一部は反応管内に付着するが、第１の前駆体の多くは、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。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 introduced boric acid ester and ammonia react in a heated reaction tube to produce a first precursor (white powder). A part of the generated first precursor adheres to the inside of the reaction tube, but most of the first precursor is sent to the recovery vessel attached to the tip of the reaction tube by the inert gas or unreacted ammonia gas. And be recovered. The time for reacting the boric acid ester with ammonia (reaction time) is preferably within 30 seconds. The reaction time is the time during which the borate 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 borate 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 part of the reaction tube).
　第２の工程では、第１の工程で得られた第１の前駆体を、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、反応時間が短くなり、結果として、最終的に得られる窒化ホウ素粒子の平均粒子径が大きくなる傾向にあり、ＢＥＴ径が小さくなる傾向にある。 In the second step, the first precursor obtained in the first step is placed in another reaction tube (for example, an alumina tube) installed in a resistance heating furnace, and nitrogen gas and ammonia gas are separately charged. Introduce into the reaction tube. 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, as the flow rate of ammonia gas increases, the reaction time tends to be short, and as a result, the average particle size of the finally obtained boron nitride particles tends to be large, and the BET diameter tends to be small.
　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、第２の前駆体が得られる。 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. This gives a second precursor.
　第２の工程が終了した後、抵抗加熱炉の電源を切り、窒素ガス及びアンモニアガスの導入を停止し、反応管内の温度を常温（１０～３０℃）まで下げた状態で、第２の前駆体を静置する、静置する時間は、例えば、０．５時間以上であってよく、９６時間以下であってよい。 After the second step is completed, the power of the resistance heating furnace is turned off, the introduction of nitrogen gas and ammonia gas is stopped, and the temperature in the reaction tube is lowered to room temperature (10 to 30 ° C.), and the second precursor is used. The resting time of the body may be, for example, 0.5 hours or more and 96 hours or less.
　第３の工程では、窒素ガス及びアンモニアガスを反応管内に再び導入すると共に、反応管を１０００～１６００℃に再び加熱する。窒素ガス及びアンモニアガスの流量、並びに加熱する時間の例は、第２の工程で説明したものと同様であってよい。第２の工程の条件と第３の工程の条件は、互いに同一であってよく、互いに異なっていてもよい。これにより、第３の前駆体が得られる。 In the third step, nitrogen gas and ammonia gas are reintroduced into the reaction tube, and the reaction tube is heated again to 1000 to 1600 ° C. Examples of the flow rates of nitrogen gas and ammonia gas, and the heating time may be the same as those described in the second step. The conditions of the second step and the conditions of the third step may be the same as each other or may be different from each other. This gives a third precursor.
　第４の工程では、第３の工程で得られた第３の前駆体を窒化ホウ素製ルツボに入れ、誘導加熱炉において、窒素雰囲気下で１８００～２２００℃に加熱する。加熱する時間は、例えば、０．５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、上述した特性を有する窒化ホウ素粒子が得られる。 In the fourth step, the third precursor obtained in the third step is placed in a boron nitride crucible and heated to 1800 to 2200 ° C. in an induction heating furnace under a nitrogen atmosphere. The heating time may be, for example, 0.5 hours or more, and may be 10 hours or less. As a result, boron nitride particles having the above-mentioned characteristics can be obtained.
　以上説明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。上記の窒化ホウ素粒子を用いることにより、低誘電率かつ低誘電正接の放熱部材が得られる。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として用いられる。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。 The boron nitride particles described above are suitably used for, for example, a heat radiating member. By using the above-mentioned boron nitride particles, a heat radiating member having a low dielectric constant and a low dielectric loss tangent can be obtained. When the boron nitride particles are used for a heat radiating member, they are used, for example, as 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.
　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、ポリオレフィン（ポリエチレン等）、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, polyolefin (polyethylene, etc.), polyimide, polyamideimide, polyetherimide, and poly. Butylene terephthalate, polyethylene terephthalate, 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 / ethylene / propylene / diene rubber-styrene) resin.
　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.
　樹脂組成物は、上記の窒化ホウ素粒子以外の窒化ホウ素粒子（例えば、鱗片状の一次粒子が凝集してなる塊状窒化ホウ素粒子等の公知の窒化ホウ素粒子）を更に含有してもよい。 The resin composition may further contain boron nitride particles other than the above-mentioned boron nitride particles (for example, known boron nitride particles such as massive boron nitride particles formed by aggregating scaly primary particles).
　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１～３］
　以下の手順により、窒化ホウ素粒子を作製した。
　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、表１に示す温度まで昇温した。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、第１の前駆体（白色粉末）を得た。なお、反応時間は表１に示すとおりである。 [Examples 1 to 3]
Boron nitride particles were prepared by the following procedure.
First, in the first step, the reaction tube (quartz tube) installed in the resistance heating furnace was heated to raise the temperature to the temperature shown in Table 1. 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 first precursor (white powder). The reaction time is as shown in Table 1.
　続いて、第２の工程では、第１の工程で得られた第１の前駆体を、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、窒素ガス及びアンモニアガスをそれぞれ別々に、表１に示す流量で反応管内に導入した。そして、反応管を表１に示す温度及び時間で加熱した。これにより、第２の前駆体を得た。 Subsequently, in the second step, the first precursor obtained in the first step is placed in another reaction tube (alumina tube) installed in the resistance heating furnace, and nitrogen gas and ammonia gas are charged, respectively. Separately, they were introduced into the reaction tube at the flow rates shown in Table 1. Then, the reaction tube was heated at the temperature and time shown in Table 1. This gave a second precursor.
　続いて、抵抗加熱炉の電源を切り、窒素ガス及びアンモニアガスの導入を停止し、反応管内の温度を２５℃まで下げた状態で、第２の前駆体を２時間静置した。 Subsequently, the power of the resistance heating furnace was turned off, the introduction of nitrogen gas and ammonia gas was stopped, and the temperature in the reaction tube was lowered to 25 ° C., and the second precursor was allowed to stand for 2 hours.
　続いて、第３の工程では、窒素ガス及びアンモニアガスを表１に示す流量で反応管内に再び導入すると共に、反応管を表１に示す温度及び時間で再び加熱した。これにより、第３の前駆体を得た。 Subsequently, in the third step, nitrogen gas and ammonia gas were reintroduced into the reaction tube at the flow rates shown in Table 1, and the reaction tube was heated again at the temperature and time shown in Table 1. This gave a third precursor.
　続いて、第４の工程では、第３の工程で得られた第３の前駆体を窒化ホウ素製ルツボに入れ、誘導加熱炉において、窒素雰囲気下で表１に示す温度及び時間で加熱した。これにより、窒化ホウ素粒子を得た。 Subsequently, in the fourth step, the third precursor obtained in the third step was placed in a boron nitride crucible and heated in an induction heating furnace under a nitrogen atmosphere at the temperature and time shown in Table 1. As a result, boron nitride particles were obtained.
［比較例１］
　第３の工程を実施しなかった以外は、実施例１と同様にして、窒化ホウ素粒子を得た。 [Comparative Example 1]
Boron nitride particles were obtained in the same manner as in Example 1 except that the third step was not carried out.
　得られた各窒化ホウ素粒子について、平均粒子径、ＢＥＴ径、及び平均円形度を以下の方法によりそれぞれ測定した。結果を表１に示す。 For each of the obtained boron nitride particles, the average particle size, BET diameter, and average circularity were measured by the following methods. The results are shown in Table 1.
（平均粒子径）
　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。 (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 Nippon Seiki Seisakusho, 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.
（ＢＥＴ径）
　ＢＥＴ径は、下記式により算出した。
　　ＢＥＴ径＝窒化ホウ素１ｇで真球の１粒子となると仮定したときの直径／（ＢＥＴ比表面積／窒化ホウ素１ｇで真球の１粒子となると仮定したときの表面積）
　ここで、
・窒化ホウ素１ｇで真球の１粒子となると仮定したときの直径
　＝（６／（窒化ホウ素粒子の密度×π））１／３
　（ただし、窒化ホウ素粒子の密度として２．２６ｇ／ｃｍ３を用いる）
・窒化ホウ素１ｇで真球の１粒子となると仮定したときの表面積
　＝π×（窒化ホウ素１ｇで真球の１粒子となると仮定したときの直径）２
・ＢＥＴ比表面積
　ＪＩＳ　Ｚ　８８０３：２０１３に準拠し、窒素ガスを使用してＢＥＴ一点法により測定した窒化ホウ素粒子のＢＥＴ比表面積
である。 (BET diameter)
The BET diameter was calculated by the following formula.
BET diameter = diameter when 1 g of boron nitride is assumed to be one true sphere particle / (BET specific surface area / surface area when 1 g of boron nitride is assumed to be one true sphere)
here,
-Diameter assuming that 1 g of boron nitride becomes one true sphere particle = (6 / (density of boron nitride particles x π)) 1/3
(However, 2.26 g / cm 3 is used as the density of boron nitride particles)
・ Surface area when 1 g of boron nitride is assumed to be one true sphere particle = π × (diameter when 1 g of boron nitride is assumed to be one true sphere particle) 2
-BET specific surface area This is the BET specific surface area of the boron nitride particles measured by the BET one-point method using nitrogen gas in accordance with JIS Z 8803: 2013.
（平均円形度）
　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。 (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.
　得られた各窒化ホウ素粒子を用いたときの誘電率及び誘電正接を以下の方法により測定した。結果を表１に示す。
　窒化ホウ素粒子が２０体積％となる分量で、窒化ホウ素粒子とポリエチレン（日本ポリエチレン（株）製、商品名「ノバテックＨＹ５４０」）とを混錬し、シート成形を行って、０．２ｍｍ厚のシートを得た。混錬及びシート成形は、二軸押し出し機を用い、温度１８０℃の条件で行った。空洞共振器法の測定装置を用いて、周波数３６ＧＨｚ、温度２５℃の条件で得られたシートの測定を行い、シートの誘電率及び誘電正接を求めた。 The permittivity and dielectric loss tangent when each of the obtained boron nitride particles was used was measured by the following method. The results are shown in Table 1.
Boron nitride particles are kneaded with polyethylene (manufactured by Japan Polyethylene Corporation, trade name "Novatec HY540") in an amount that makes the amount of boron nitride particles 20% by volume, and sheet molding is performed to obtain a 0.2 mm thick sheet. Got Kneading and sheet forming were carried out using a twin-screw extruder under the condition of a temperature of 180 ° C. Using a measuring device of the cavity resonator method, the sheet obtained under the conditions of a frequency of 36 GHz and a temperature of 25 ° C. was measured, and the dielectric constant and the dielectric loss tangent of the sheet were determined.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001

Claims (3)

  1. 　平均粒子径が４５０ｎｍ以上８００ｎｍ以下であり、ＢＥＴ径が１６０ｎｍ以上３００ｎｍ以下である、窒化ホウ素粒子。 Boron nitride particles having an average particle diameter of 450 nm or more and 800 nm or less and a BET diameter of 160 nm or more and 300 nm or less.
  2. 　平均円形度が０．８以上である、請求項１に記載の窒化ホウ素粒子。 The boron nitride particles according to claim 1, which have an average circularity of 0.8 or more.
  3. 　樹脂と、請求項１又は２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 claim 1 or 2.
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JP2019116401A (en) * 2017-12-27 2019-07-18 昭和電工株式会社 Hexagonal crystal boron nitride powder and method for producing the same, and composition and heat dissipation member using the same

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