JP6826065B2 - Thermally conductive composite materials, thermally conductive fillers and their manufacturing methods - Google Patents
Thermally conductive composite materials, thermally conductive fillers and their manufacturing methods Download PDFInfo
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- JP6826065B2 JP6826065B2 JP2018051313A JP2018051313A JP6826065B2 JP 6826065 B2 JP6826065 B2 JP 6826065B2 JP 2018051313 A JP2018051313 A JP 2018051313A JP 2018051313 A JP2018051313 A JP 2018051313A JP 6826065 B2 JP6826065 B2 JP 6826065B2
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- boron nitride
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- nitride fine
- thermally conductive
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- 239000011231 conductive filler Substances 0.000 title claims description 79
- 238000004519 manufacturing process Methods 0.000 title claims description 23
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- 229910052582 BN Inorganic materials 0.000 claims description 325
- 239000010419 fine particle Substances 0.000 claims description 308
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- 238000010298 pulverizing process Methods 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 21
- 238000003776 cleavage reaction Methods 0.000 claims description 18
- 230000007017 scission Effects 0.000 claims description 18
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- 239000010432 diamond Substances 0.000 claims description 10
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Description
本発明は、熱伝導性複合材料及びそれに用いる熱伝導性フィラー、並びにそれらの製造方法に関する。 The present invention relates to a thermally conductive composite material, a thermally conductive filler used therein, and a method for producing the same.
窒化ホウ素は熱伝導性の高い高絶縁性の材料として知られており、窒化ホウ素粒子を熱伝導性フィラーとしてマトリックス中に分散させた様々な熱伝導性複合材料が開発されている。例えば、特開２０１０−２６０２２５号公報（特許文献１）では、平均粒子径が相違する２種類の窒化ホウ素粉末を熱伝導性フィラーとして含有するシリコーン積層体を積層方向から切断してなる熱伝導性成形体が開示されている。 Boron nitride is known as a highly insulating material having high thermal conductivity, and various thermally conductive composite materials in which boron nitride particles are dispersed in a matrix as a thermally conductive filler have been developed. For example, in Japanese Patent Application Laid-Open No. 2010-260225 (Patent Document 1), a silicone laminate containing two types of boron nitride powders having different average particle diameters as a thermally conductive filler is cut from the lamination direction to obtain thermal conductivity. The molded body is disclosed.
また、国際公開２００８／０４２４４６号公報（特許文献２）では、少なくとも２種類の異なるタイプの窒化ホウ素粉体材料として、プレートレット窒化ホウ素粉体材料と窒化ホウ素粉体材料の球状凝集体とを含むポリマー組成物が開示されている。 Further, in International Publication No. 2008/042446 (Patent Document 2), at least two different types of boron nitride powder materials include a platelet boron nitride powder material and a spherical aggregate of the boron nitride powder material. Polymer compositions are disclosed.
さらに、特開２０１５−６９８５号公報（特許文献３）では、窒化ホウ素凝集粒子中の一次粒子同士がカードハウス構造を有している窒化ホウ素凝集粒子よりなるフィラーと樹脂とを含む組成物が開示されている。 Further, Japanese Patent Application Laid-Open No. 2015-6985 (Patent Document 3) discloses a composition containing a filler and a resin composed of boron nitride agglomerated particles in which the primary particles in the boron nitride agglomerated particles have a cardhouse structure. Has been done.
しかしながら、このような従来の熱伝導性複合材料であっても、熱伝導性の向上に限界があり、必ずしも十分な熱伝導性を達成できるものではなかった。 However, even with such a conventional heat conductive composite material, there is a limit to the improvement of the heat conductivity, and it is not always possible to achieve sufficient heat conductivity.
本発明は、上記従来技術の有する課題に鑑みてなされたものであり、熱伝導性を効率良く向上させることが可能な熱伝導性フィラー及びその製造方法と、優れた熱伝導性を有する熱伝導性複合材料及びその製造方法とを提供することを目的とする。 The present invention has been made in view of the above-mentioned problems of the prior art, and has a thermal conductivity filler capable of efficiently improving thermal conductivity, a method for producing the same, and thermal conductivity having excellent thermal conductivity. It is an object of the present invention to provide a sex composite material and a method for producing the same.
本発明者らは、上記目的を達成すべく鋭意研究を重ねた結果、窒化ホウ素粒子を含有する流体を高圧でノズルから噴射させて湿式衝突粉砕することにより、熱伝導性を効率良く向上させることが可能な熱伝導性フィラーが得られるようになり、その熱伝導性フィラーを用いることによって優れた熱伝導性を有する熱伝導性複合材料が得られることを見出し、本発明を完成するに至った。 As a result of diligent research to achieve the above object, the present inventors have efficiently improved thermal conductivity by injecting a fluid containing boron nitride particles from a nozzle at a high pressure and performing wet collision pulverization. It has become possible to obtain a heat conductive filler capable of obtaining a heat conductive filler, and it has been found that a heat conductive composite material having excellent heat conductivity can be obtained by using the heat conductive filler, and the present invention has been completed. ..
本発明に係る熱伝導性フィラーの製造方法は、窒化ホウ素粒子を含有する流体を高圧でノズルから噴射させて湿式衝突粉砕することにより、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子を含む窒化ホウ素微粒子からなる熱伝導性フィラーを得ることを特徴とする方法である。 In the method for producing a thermally conductive filler according to the present invention , a fluid containing boron nitride particles is injected from a nozzle at a high pressure to perform wet collision pulverization to obtain partially opened boron nitride fine particles in which the boron nitride fine particles are partially opened. This method is characterized by obtaining a thermally conductive filler composed of boron nitride fine particles containing the particles.
このような本発明に係る熱伝導性フィラーの製造方法においては、前記高圧が３０〜２５０ＭＰａの圧力であり、前記流体を前記ノズルから噴射させる際の流速が２００〜８００ｍ／ｓであることが好ましい。 In such a method for producing a thermally conductive filler according to the present invention , it is preferable that the high pressure is a pressure of 30 to 250 MPa and the flow velocity when injecting the fluid from the nozzle is 200 to 800 m / s. ..
また、本発明に係る熱伝導性フィラーは、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子を含有する窒化ホウ素微粒子からなり、前記部分劈開窒化ホウ素微粒子の含有率が前記窒化ホウ素微粒子の全量に対して５体積％以上であることを特徴とするものである。 Further, the thermally conductive filler according to the present invention is composed of boron nitride fine particles containing partially opened boron nitride fine particles in which the boron nitride fine particles are partially opened, and the content of the partially opened boron nitride fine particles is that of the boron nitride fine particles. It is characterized in that it is 5% by volume or more with respect to the total amount.
このような本発明に係る熱伝導性フィラーにおいては、前記窒化ホウ素微粒子の平均粒子径が１〜１００μｍであることが好ましく、また、前記窒化ホウ素微粒子が六方晶系の板状窒化ホウ素微粒子であることが好ましい。 In such a thermally conductive filler according to the present invention , the average particle size of the boron nitride fine particles is preferably 1 to 100 μm, and the boron nitride fine particles are hexagonal plate-shaped boron nitride fine particles. Is preferable.
本発明の熱伝導性複合材料の製造方法は、
六方晶系の板状窒化ホウ素粒子を含有する流体を高圧でノズルから噴射させて湿式衝突粉砕することにより、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子を含む六方晶系の板状窒化ホウ素微粒子を得る工程と、
前記部分劈開窒化ホウ素微粒子を含む六方晶系の板状窒化ホウ素微粒子と、立方晶窒化ホウ素、ダイヤモンド、窒化アルミニウム、酸化アルミニウム、酸化マグネシウム、酸化亜鉛、窒化ケイ素及び炭化ケイ素からなる群から選択される少なくとも一種の熱伝導率が２０Ｗ／ｍＫ以上である高熱伝導性微粒子とを熱伝導性フィラーとしてマトリックス中に分散させて、前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子を含有する熱伝導性複合材料を得る工程と、
を含むことを特徴とする方法である。
The method for producing a thermally conductive composite material of the present invention is
By injecting a fluid containing hexagonal plate-shaped boron nitride particles from a nozzle at high pressure and performing wet collision pulverization, the boron nitride fine particles are partially opened to form a hexagonal plate containing partially opened boron nitride fine particles. The process of obtaining boron nitride fine particles and
It is selected from the group consisting of hexagonal plate-shaped boron nitride fine particles containing the partially opened boron nitride fine particles , and cubic boron nitride, diamond, aluminum nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon nitride and silicon carbide. At least one kind of highly thermally conductive fine particles having a thermal conductivity of 20 W / mK or more was dispersed in the matrix as a thermally conductive filler, and the matrix was filled and swollen in the open voids of the partially opened boron nitride fine particles. The process of obtaining a thermally conductive composite material containing swelled boron nitride fine particles,
It is a method characterized by including.
このような本発明の熱伝導性複合材料の製造方法においては、前記高圧が３０〜２５０ＭＰａの圧力であり、前記流体を前記ノズルから噴射させる際の流速が２００〜８００ｍ／ｓであることが好ましい。 In such a method for producing a thermally conductive composite material of the present invention, it is preferable that the high pressure is a pressure of 30 to 250 MPa and the flow velocity when injecting the fluid from the nozzle is 200 to 800 m / s. ..
また、本発明の熱伝導性複合材料は、六方晶系の板状窒化ホウ素微粒子と、立方晶窒化ホウ素、ダイヤモンド、窒化アルミニウム、酸化アルミニウム、酸化マグネシウム、酸化亜鉛、窒化ケイ素及び炭化ケイ素からなる群から選択される少なくとも一種の熱伝導率が２０Ｗ／ｍＫ以上である高熱伝導性微粒子とを熱伝導性フィラーとしてマトリックス中に分散させてなるものであって、
前記窒化ホウ素微粒子の少なくとも一部が、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子であり、
前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子が前記複合材料に含有されており、
前記複合材料の断面基準で、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積が、前記複合材料の断面面積に対して１〜５０％である、
ことを特徴とするものである。
Further, the thermally conductive composite material of the present invention is a group consisting of hexagonal plate-shaped boron nitride fine particles , cubic boron nitride, diamond, aluminum nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon nitride and silicon carbide. At least one kind of fine particles having a thermal conductivity of 20 W / mK or more selected from the above is dispersed in a matrix as a heat conductive filler.
At least a part of the boron nitride fine particles is partially cleaved boron nitride fine particles in which the boron nitride fine particles are partially cleaved.
The composite material contains swollen boron nitride fine particles in which the matrix is filled and swollen in the cleavage voids of the partially cleaved boron nitride fine particles.
Based on the cross-sectional area of the composite material, the total area of the region corresponding to the swollen boron nitride fine particles is 1 to 50% of the cross-sectional area of the composite material.
It is characterized by that.
このような本発明の熱伝導性複合材料においては、前記部分劈開窒化ホウ素微粒子の含有率が前記窒化ホウ素微粒子の全量に対して５体積％以上であることが好ましく、また、前記熱伝導性フィラーの含有率が前記複合材料の全量に対して１０〜９０体積％であることが好ましい。 In such a thermally conductive composite material of the present invention, the content of the partially opened boron nitride fine particles is preferably 5% by volume or more based on the total amount of the boron nitride fine particles, and the thermally conductive filler. The content of the composite material is preferably 10 to 90% by volume based on the total amount of the composite material.
このように本発明の熱伝導性複合材料において前記高熱伝導性微粒子が含有されている場合は、前記窒化ホウ素微粒子の含有率が前記熱伝導性フィラーの全量に対して５体積％以上であることが好ましい。 When the high thermal conductive fine particles are contained in the thermally conductive composite material of the present invention as described above, the content of the boron nitride fine particles is 5% by volume or more based on the total amount of the thermally conductive filler. Is preferable.
なお、本発明の熱伝導性フィラーを用いた熱伝導性複合材料によって優れた熱伝導性が得られる理由は必ずしも定かではないが、本発明者らは以下のように推察する。すなわち、本発明の熱伝導性複合材料においては、熱伝導性フィラーとして用いられる窒化ホウ素微粒子のうちの少なくとも一部が、部分的に劈開して粒子の内部や端部に劈開面を有する部分劈開窒化ホウ素微粒子となっており、このような部分劈開窒化ホウ素微粒子は熱伝導性フィラーとしてマトリックス中に分散させる際に劈開空隙中にマトリックスが入り込んで膨潤した状態となる。そのため、部分的な劈開が形成されていない窒化ホウ素微粒子と比較して、このように膨潤した窒化ホウ素微粒子は見掛けの平均直径が増大するとともに変形しやすくなり、それによって複合材料中で窒化ホウ素微粒子間の接触が生じやすくなるとともに密着性が向上し、窒化ホウ素微粒子間の接触部位を通じて熱が拡散する熱伝導パスのネットワーク構造が効率良く形成されるとともに微粒子間の界面熱抵抗が大幅に低減するため、得られる複合材料の熱伝導性が向上して優れた熱伝導性が達成されるようになると本発明者らは推察する。また、窒化ホウ素微粒子内部の未劈開部分は、劈開前の窒化ホウ素粒子の高熱伝導性構造を保持しているため、粒子内部の熱の伝達も効率良く行うことができ、高熱伝導性の複合材料とした時に有利である。 Although the reason why excellent thermal conductivity can be obtained by the thermally conductive composite material using the thermally conductive filler of the present invention is not always clear, the present inventors presume as follows. That is, in the thermally conductive composite material of the present invention, at least a part of the boron nitride fine particles used as the thermally conductive filler is partially cleaved to have a cleaved surface inside or at the end of the particles. The particles are boron nitride fine particles, and when such partially cleaved boron nitride fine particles are dispersed in the matrix as a heat conductive filler, the matrix enters the cleavage voids and becomes swollen. Therefore, as compared with the boron nitride fine particles in which the partial opening is not formed, the boron nitride fine particles swollen in this way increase the apparent average diameter and are easily deformed, whereby the boron nitride fine particles in the composite material are easily deformed. The contact between the particles is more likely to occur, the adhesion is improved, the network structure of the heat conduction path where heat is diffused through the contact site between the boron nitride fine particles is efficiently formed, and the interfacial thermal resistance between the fine particles is significantly reduced. Therefore, the present inventors presume that the thermal conductivity of the obtained composite material is improved and excellent thermal conductivity is achieved. Further, since the uncleaved portion inside the boron nitride fine particles retains the high thermal conductive structure of the boron nitride particles before cleavage, the heat inside the particles can be efficiently transferred, and the composite material having high thermal conductivity. It is advantageous when
また、本発明の熱伝導性フィラーの製造方法においては、窒化ホウ素粒子を含有する流体を高圧でノズルから噴射させることにより、粒子同士が衝突あるいはせん断流動により微細化することによって結晶構造の破壊や過度の微細化を抑制しつつ湿式粉砕されるとともに、粒子が流体中で高圧でせん断流動圧縮させた状態から急激に圧力を低下させることにより、粒子に対して加わっていた圧力が急激に消失することで粒子内部から外部に向かって膨張する力が働き、それに伴って粒子が外側に引っ張られることによって粒子の内部や端部に部分的な劈開が生じて部分劈開窒化ホウ素微粒子が得られると本発明者らは推察する。 Further, in the method for producing a thermally conductive filler of the present invention, by injecting a fluid containing boron nitride particles from a nozzle at a high pressure, the particles collide with each other or become finer due to shear flow, thereby destroying the crystal structure. While wet pulverization is performed while suppressing excessive fineness, the pressure applied to the particles suddenly disappears by rapidly reducing the pressure from the state where the particles are sheared, flowed and compressed at high pressure in the fluid. As a result, a force that expands from the inside of the particle to the outside works, and the particle is pulled outward accordingly, causing partial opening inside and at the end of the particle, and partial opening boron nitride fine particles are obtained. The inventors speculate.
本発明によれば、熱伝導性を効率良く向上させることが可能な熱伝導性フィラー及びその製造方法と、優れた熱伝導性を有する熱伝導性複合材料及びその製造方法とを提供することが可能となる。 According to the present invention, it is possible to provide a thermally conductive filler capable of efficiently improving thermal conductivity and a method for producing the same, and a thermally conductive composite material having excellent thermal conductivity and a method for producing the same. It will be possible.
以下、本発明をその好適な実施形態に即して詳細に説明する。 Hereinafter, the present invention will be described in detail according to its preferred embodiment.
先ず、本発明の熱伝導性フィラーについて説明する。本発明の熱伝導性フィラーは、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子を含有する窒化ホウ素微粒子からなり、前記部分劈開窒化ホウ素微粒子の含有率が前記窒化ホウ素微粒子の全量に対して５体積％以上であることを特徴とするものである。 First, the thermally conductive filler of the present invention will be described. The thermally conductive filler of the present invention is composed of boron nitride fine particles containing partially opened boron nitride fine particles in which the boron nitride fine particles are partially opened, and the content of the partially opened boron nitride fine particles is relative to the total amount of the boron nitride fine particles. It is characterized in that it is 5% by volume or more.
本発明の熱伝導性フィラーは、窒化ホウ素（ＢＮ）の微粒子からなるものであり、窒化ホウ素には六方晶系の常圧相や立方晶系の高圧相等があるが、劈開のしやすさや熱伝導性の観点から六方晶系の板状窒化ホウ素微粒子であることが好ましい。 The thermally conductive filler of the present invention is composed of boron nitride (BN) fine particles, and boron nitride has a hexagonal normal pressure phase, a cubic high pressure phase, and the like, but it is easy to open and heat. From the viewpoint of conductivity, hexagonal plate-shaped boron nitride fine particles are preferable.
また、本発明の熱伝導性フィラーを構成する窒化ホウ素微粒子の大きさは特に制限されないが、平均粒子径が１〜１００μｍであることが好ましく、２〜５０μｍであることがより好ましく、３〜３０μｍであることが特に好ましい。窒化ホウ素微粒子の平均粒子径が前記下限未満では、得られる複合材料において窒化ホウ素微粒子間の粒界抵抗及び複合材料中の粒界数が増大するため熱伝導性が低下する傾向にあり、他方、前記上限を超えると、得られる複合材料における熱伝導性フィラーの分散均一性及び充填率が低下して熱伝導性が低下する傾向にある。なお、本明細書において、「平均粒子径」は、レーザー回折・散乱法によって求めた粒度分布における累積５０％粒子径（メディアン径：Ｄ５０）を意味する。 The size of the boron nitride fine particles constituting the thermally conductive filler of the present invention is not particularly limited, but the average particle diameter is preferably 1 to 100 μm, more preferably 2 to 50 μm, and 3 to 30 μm. Is particularly preferable. If the average particle size of the boron nitride fine particles is less than the above lower limit, the grain boundary resistance between the boron nitride fine particles and the number of grain boundaries in the composite material tend to increase in the obtained composite material, so that the thermal conductivity tends to decrease. When the above upper limit is exceeded, the dispersion uniformity and filling rate of the thermally conductive filler in the obtained composite material tend to decrease, and the thermal conductivity tends to decrease. In the present specification, the "average particle size" means the cumulative 50% particle size (median size: D50) in the particle size distribution obtained by the laser diffraction / scattering method.
本発明においては、前記窒化ホウ素微粒子のうちの少なくとも一部が、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子となっていることが必要である。このような部分劈開窒化ホウ素微粒子は、窒化ホウ素微粒子が部分的に劈開して粒子の内部や端部に劈開面を有するものであり、熱伝導性フィラーとしてマトリックス中に分散させる際に劈開空隙（対向する劈開面の間の空隙）中にマトリックスが入り込んで膨潤した状態（膨潤窒化ホウ素微粒子）となる。 In the present invention, it is necessary that at least a part of the boron nitride fine particles is partially cleaved boron nitride fine particles in which the boron nitride fine particles are partially cleaved. Such partially cleaved boron nitride fine particles are those in which the boron nitride fine particles are partially cleaved and have a cleaved surface inside or at the end of the particles, and when dispersed in the matrix as a heat conductive filler, the cleaved voids ( The matrix enters the gap between the opposing cleavage planes) and swells (swelled boron nitride fine particles).
なお、このような部分劈開窒化ホウ素微粒子は、得られる複合材料の断面の走査型電子顕微鏡（ＳＥＭ）写真において膨潤窒化ホウ素微粒子として観察され、明度と形状に基づいて、劈開されずに未劈開のまま残っている未劈開窒化ホウ素粒子や、窒化ホウ素粒子が劈開により完全に分割されて得られた内部や端部に劈開面を有していない完全劈開窒化ホウ素微粒子と区別することができる。さらに、ＦＩＢ−ＳＥＭ（集束イオンビーム−走査型電子顕微鏡）による三次元分散構造観察によっても区別が可能である。以下、このような未劈開窒化ホウ素粒子と完全劈開窒化ホウ素微粒子とを合わせて「非膨潤窒化ホウ素微粒子」と総称する。 Such partially cleaved boron nitride fine particles were observed as swollen boron nitride fine particles in a scanning electron microscope (SEM) photograph of the cross section of the obtained composite material, and were not cleaved but uncleavage based on the brightness and shape. It can be distinguished from the uncleavage boron nitride particles that remain as they are and the completely open boron nitride fine particles that do not have an open surface at the inside or the end obtained by completely dividing the boron nitride particles by cleavage. Furthermore, distinction is possible by observing the three-dimensional dispersed structure with a FIB-SEM (focused ion beam-scanning electron microscope). Hereinafter, such uncleavage boron nitride particles and completely cleavage boron nitride fine particles are collectively referred to as “non-cleavage boron nitride fine particles”.
本発明の熱伝導性フィラーにおいては、前記部分劈開窒化ホウ素微粒子の含有率が、前記窒化ホウ素微粒子の全量（前記部分劈開窒化ホウ素微粒子と前記未劈開窒化ホウ素粒子と前記完全劈開窒化ホウ素微粒子との総量）に対して５体積％以上となっていることが必要である。前記部分劈開窒化ホウ素微粒子の含有率が５体積％未満では、得られる複合材料中で窒化ホウ素微粒子間の接触部位を通じて熱が拡散する熱伝導パスのネットワーク構造が十分に形成されず、得られる複合材料の熱伝導性が十分に向上しない。また、得られる複合材料の熱伝導性がより向上するという観点から、前記部分劈開窒化ホウ素微粒子の含有率が前記窒化ホウ素微粒子の全量に対して１０体積％以上であることが好ましく、２０体積％以上であることがより好ましい。 In the thermally conductive filler of the present invention, the content of the partially opened boron nitride fine particles is the total amount of the said boron nitride fine particles (the said partially opened boron nitride fine particles, the unopened boron nitride particles, and the completely opened boron nitride fine particles. It is necessary that it is 5% by volume or more with respect to the total amount). If the content of the partially opened boron nitride fine particles is less than 5% by volume, the network structure of the heat conduction path in which heat is diffused through the contact sites between the boron nitride fine particles in the obtained composite material is not sufficiently formed, and the obtained composite is obtained. The thermal conductivity of the material is not sufficiently improved. Further, from the viewpoint of further improving the thermal conductivity of the obtained composite material, the content of the partially cleaved boron nitride fine particles is preferably 10% by volume or more, preferably 20% by volume, based on the total amount of the boron nitride fine particles. The above is more preferable.
なお、前記窒化ホウ素微粒子の全量に対する前記部分劈開窒化ホウ素微粒子の含有率は、以下のようにして求められる。すなわち、得られる複合材料の断面の走査型電子顕微鏡写真（ＳＥＭ像）において、明度と形状に基づいて、
（ｉ）前記膨潤窒化ホウ素微粒子（前記部分劈開窒化ホウ素微粒子とその劈開空隙に取り込まれたマトリックス）に相当する領域と、
（ｉｉ）前記非膨潤窒化ホウ素微粒子（前記未劈開窒化ホウ素粒子及び前記完全劈開窒化ホウ素微粒子）に相当する領域と、
（ｉｉｉ）マトリックスのうち前記膨潤窒化ホウ素微粒子中に取り込まれずに存在するマトリックスに相当する領域と、
を区別して認識し、公知の二値化等の画像解析手法によりそれぞれの領域の面積を求めることができる。したがって、得られる複合材料の断面について、例えば、横６０μｍ以上、縦４０μｍ以上の測定領域を任意に１０箇所以上抽出し、それぞれの測定領域のＳＥＭ像において（ｉｉ）前記非膨潤窒化ホウ素微粒子に相当する領域の合計面積を求め、当該測定領域における全ての窒化ホウ素が未劈開窒化ホウ素粒子である場合の全窒化ホウ素粒子に相当する領域の合計面積との関係から当該領域における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率を求めることができる。そして、全ての測定領域の平均値を算出することにより、用いた熱伝導性フィラーにおける前記窒化ホウ素微粒子の全量に対する前記部分劈開窒化ホウ素微粒子の含有率（平均値）が求められる。
The content of the partially cleaved boron nitride fine particles with respect to the total amount of the boron nitride fine particles is determined as follows. That is, in a scanning electron micrograph (SEM image) of the cross section of the obtained composite material, based on the brightness and shape.
(I) A region corresponding to the swollen boron nitride fine particles (the partially cleaved boron nitride fine particles and the matrix incorporated in the cleaved voids).
(Ii) A region corresponding to the non-cleavage boron nitride fine particles (the uncleavage boron nitride particles and the fully cleaved boron nitride fine particles), and
(Iii) A region of the matrix corresponding to the matrix that exists without being incorporated into the swollen boron nitride fine particles.
Can be distinguished and recognized, and the area of each region can be obtained by a known image analysis method such as binarization. Therefore, with respect to the cross section of the obtained composite material, for example, 10 or more measurement regions having a width of 60 μm or more and a length of 40 μm or more are arbitrarily extracted, and in the SEM image of each measurement region, (ii) corresponds to the non-swelling boron nitride fine particles. The total area of the region to be measured is obtained, and the total area of the region corresponding to the total boron nitride particles when all the boron nitride in the measurement region is unopened boron nitride particles is used with respect to the total amount of the boron nitride fine particles in the region. The content of partially opened boron nitride fine particles can be determined. Then, by calculating the average value of all the measurement regions, the content rate (average value) of the partially cleaved boron nitride fine particles with respect to the total amount of the boron nitride fine particles in the used thermally conductive filler can be obtained.
このように本発明の熱伝導性フィラーは、前記部分劈開窒化ホウ素微粒子を所定量以上含有する前記窒化ホウ素微粒子からなるものであるが、マトリックスへの分散性をより向上させる観点から、窒化ホウ素微粒子の表面に水酸基、カルボキシル基、エステル基、アミド基、アミノ基等の官能基が結合していてもよい。 As described above, the thermally conductive filler of the present invention comprises the boron nitride fine particles containing the partial open boron nitride fine particles in a predetermined amount or more, but from the viewpoint of further improving the dispersibility in the matrix, the boron nitride fine particles A functional group such as a hydroxyl group, a carboxyl group, an ester group, an amide group, or an amino group may be bonded to the surface of the above.
また、本発明の熱伝導性フィラーは、前記部分劈開窒化ホウ素微粒子を所定量以上含有する前記窒化ホウ素微粒子のみからなるものであってもよいが、前記窒化ホウ素微粒子に加えて、例えば、板状グラファイト、板状窒化アルミニウム、板状アルミナ、アルミフレーク、銅フレーク、ダイヤモンド、窒化ケイ素等の他の熱伝導性粒子や、ＳｉＣ繊維、炭素繊維、カーボンナノチューブ、金属めっきを施した繊維、金属繊維等の他の熱伝導性繊維を更に含有していてもよい。 Further, the thermally conductive filler of the present invention may consist only of the boron nitride fine particles containing the partially opened boron nitride fine particles in a predetermined amount or more, but in addition to the boron nitride fine particles, for example, a plate shape. Other thermally conductive particles such as graphite, plate aluminum nitride, plate alumina, aluminum flakes, copper flakes, diamonds, silicon nitride, SiC fibers, carbon fibers, carbon nanotubes, metal-plated fibers, metal fibers, etc. It may further contain other thermally conductive fibers.
このように前記熱伝導性フィラーとして、前記窒化ホウ素微粒子に加えて他の熱伝導性材料が含有されている場合、他の熱伝導性材料として熱伝導率が２０Ｗ／ｍＫ以上である高熱伝導性微粒子が含有されていることが好ましく、そのような高熱伝導性微粒子としては等方的に高熱伝導性を有するものがより好ましい。このように前記窒化ホウ素微粒子に加えて前記高熱伝導性微粒子が含有されることにより、得られる熱伝導性複合材料における熱伝導性がより向上する傾向にある。 As described above, when the heat conductive filler contains other heat conductive materials in addition to the boron nitride fine particles, the other heat conductive materials have high thermal conductivity of 20 W / mK or more. It is preferable that fine particles are contained, and as such high thermal conductivity fine particles, those having isotropic high thermal conductivity are more preferable. By containing the high thermal conductive fine particles in addition to the boron nitride fine particles in this way, the thermal conductivity of the obtained thermally conductive composite material tends to be further improved.
また、このように前記高熱伝導性微粒子が含有されている場合は、前記窒化ホウ素微粒子が六方晶系の板状窒化ホウ素微粒子であり、かつ、前記高熱伝導性微粒子が、立方晶窒化ホウ素（熱伝導率：１０００〜２０００Ｗ／ｍＫ）、ダイヤモンド（熱伝導率：２０００〜３０００Ｗ／ｍＫ）、窒化アルミニウム（熱伝導率：１５０〜３５０Ｗ／ｍＫ）、酸化アルミニウム（熱伝導率：２０〜３５Ｗ／ｍＫ）、酸化マグネシウム（熱伝導率：４５〜６０Ｗ／ｍＫ）、酸化亜鉛（熱伝導率：２０〜３０Ｗ／ｍＫ）、窒化ケイ素（熱伝導率：８０〜１００Ｗ／ｍＫ）及び炭化ケイ素（熱伝導率：１５０〜１７０Ｗ／ｍＫ）からなる群から選択される少なくとも一種の微粒子であることが好ましい。なお、本明細書中における熱伝導率とは、室温（２０℃）における熱伝導率である。 When the high thermal conductive fine particles are contained in this way, the boron nitride fine particles are hexagonal plate-shaped boron nitride fine particles, and the high thermal conductive fine particles are cubic boron nitride (heat). Conductivity: 1000-2000 W / mK), Diamond (Thermal conductivity: 2000-3000 W / mK), Aluminum nitride (Thermal conductivity: 150-350 W / mK), Aluminum oxide (Thermal conductivity: 20-35 W / mK) , Magnesium oxide (thermal conductivity: 45-60 W / mK), zinc oxide (thermal conductivity: 20-30 W / mK), silicon nitride (thermal conductivity: 80-100 W / mK) and silicon carbide (thermal conductivity: It is preferably at least one kind of fine particles selected from the group consisting of 150 to 170 W / mK). The thermal conductivity in the present specification is the thermal conductivity at room temperature (20 ° C.).
前記高熱伝導性微粒子の大きさは特に制限されないが、平均粒子径が０．１〜１００μｍであることが好ましく、０．３〜５０μｍであることがより好ましく、０．５〜３０μｍであることが特に好ましい。前記高熱伝導性微粒子の平均粒子径が前記下限未満では、得られる複合材料において熱伝導性フィラー間の粒界抵抗及び複合材料中の粒界数が増大するため熱伝導性が低下する傾向にあり、他方、前記上限を超えると、得られる複合材料における熱伝導性フィラーの分散均一性及び充填率が低下して熱伝導性が低下する傾向にある。 The size of the highly thermally conductive fine particles is not particularly limited, but the average particle diameter is preferably 0.1 to 100 μm, more preferably 0.3 to 50 μm, and preferably 0.5 to 30 μm. Especially preferable. If the average particle size of the highly thermally conductive fine particles is less than the lower limit, the thermal conductivity tends to decrease because the grain boundary resistance between the thermally conductive fillers and the number of grain boundaries in the composite material increase in the obtained composite material. On the other hand, if the upper limit is exceeded, the dispersion uniformity and filling rate of the thermally conductive filler in the obtained composite material tend to decrease, and the thermal conductivity tends to decrease.
このように他の熱伝導性材料が含有される場合、本発明の熱伝導性フィラーの全量に対する前記窒化ホウ素微粒子の含有率は５体積％以上であることが好ましく、２０体積％以上であることがより好ましく、６０体積％以上であることが特に好ましい。 When other thermally conductive materials are contained in this way, the content of the boron nitride fine particles with respect to the total amount of the thermally conductive filler of the present invention is preferably 5% by volume or more, preferably 20% by volume or more. Is more preferable, and 60% by volume or more is particularly preferable.
なお、このように前記窒化ホウ素微粒子に加えて前記高熱伝導性微粒子が含有されることにより、得られる熱伝導性複合材料の熱伝導性がより向上する傾向となる理由は必ずしも定かではないが、本発明者らは以下のように推察する。すなわち、高熱伝導性微粒子は粒子内熱抵抗が小さいという利点があるものの、概して硬い粒子であることから粒子間熱抵抗(界面熱抵抗)が大きくなり、そのような粒子を分散せしめた従前の複合材料においては高熱伝導性微粒子による熱伝導性の向上効果を十分に引き出すことが困難であった。それに対して、本発明においては前述の通り部分劈開窒化ホウ素微粒子が含有されており、そのような部分劈開窒化ホウ素微粒子は柔かく界面熱抵抗が低いだけでなく、部分的に劈開した構造が熱伝導性フィラーのネットワーク構造を形成して熱伝導のパスが効率良く形成される。そして、そのような熱伝導性フィラーの一部として前記高熱伝導性微粒子が共存する場合は、前記高熱伝導性微粒子の周りに界面熱抵抗の低い前記部分劈開窒化ホウ素微粒子が存在することにより、高熱伝導性微粒子同士が接触する界面が少なくなり、高熱伝導性微粒子が有する優れた粒子内熱伝導性が効果的に発揮されるようになると本発明者らは推察する。 It should be noted that the reason why the thermal conductivity of the obtained thermally conductive composite material tends to be further improved by containing the highly thermally conductive fine particles in addition to the boron nitride fine particles is not necessarily clear. The present inventors infer as follows. That is, although the highly thermally conductive fine particles have the advantage of low intra-particle thermal resistance, they are generally hard particles, so the inter-particle thermal resistance (interfacial thermal resistance) is large, and the conventional composite in which such particles are dispersed. In the material, it was difficult to sufficiently bring out the effect of improving the thermal conductivity by the highly thermally conductive fine particles. On the other hand, in the present invention, as described above, the partially cleaved boron nitride fine particles are contained, and such the partially cleaved boron nitride fine particles are not only soft and have low interfacial thermal resistance, but also the partially cleaved structure is thermally conductive. A network structure of sex fillers is formed to efficiently form a heat conduction path. When the high thermal conductive fine particles coexist as a part of such a thermally conductive filler, the partial carbide fine particles having a low interfacial thermal resistance are present around the high thermal conductive fine particles, so that the heat is high. The present inventors presume that the number of interfaces where the conductive fine particles come into contact with each other is reduced, and the excellent in-particle thermal conductivity of the high thermal conductive fine particles can be effectively exhibited.
次に、本発明の熱伝導性複合材料について説明する。本発明の熱伝導性複合材料は、窒化ホウ素微粒子からなる熱伝導性フィラーをマトリックス中に分散させてなるものであって、
前記窒化ホウ素微粒子の少なくとも一部が、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子であり、
前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子が前記複合材料に含有されており、
前記複合材料の断面基準で、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積が、前記複合材料の断面面積に対して１〜５０％である、
ことを特徴とするものである。
Next, the heat conductive composite material of the present invention will be described. The thermally conductive composite material of the present invention is obtained by dispersing a thermally conductive filler composed of boron nitride fine particles in a matrix.
At least a part of the boron nitride fine particles is partially cleaved boron nitride fine particles in which the boron nitride fine particles are partially cleaved.
The composite material contains swollen boron nitride fine particles in which the matrix is filled and swollen in the cleavage voids of the partially cleaved boron nitride fine particles.
Based on the cross-sectional area of the composite material, the total area of the region corresponding to the swollen boron nitride fine particles is 1 to 50% of the cross-sectional area of the composite material.
It is characterized by that.
すなわち、本発明の熱伝導性複合材料においては、前記部分劈開窒化ホウ素微粒子を含有する前記窒化ホウ素微粒子からなる本発明の熱伝導性フィラーがマトリックス中に分散して配置されており、前記部分劈開窒化ホウ素微粒子はその劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子となっている。 That is, in the thermally conductive composite material of the present invention, the thermally conductive filler of the present invention composed of the boron nitride fine particles containing the partially opened boron nitride fine particles is dispersed and arranged in the matrix, and the partially opened boron nitride fine particles are arranged. The boron nitride fine particles are swollen boron nitride fine particles in which the matrix is filled in the open voids and swollen.
このような本発明の熱伝導性複合材料におけるマトリックスとしては、好ましくは絶縁性の樹脂や絶縁性のオイルが用いられ、具体的には特に制限されないが、樹脂としては例えば、エポキシ樹脂、フェノール樹脂、シリコーン樹脂等の熱硬化性樹脂や、ポリスチレン、ポリメチルメタクリレート、ポリカーボネート、ポリオレフィン（例えば、ポリエチレン、ポリプロピレン）、ポリオレフィンエラストマー、ポリエチレンテレフタレート、ナイロン、ＡＢＳ樹脂、ポリアミド、ポリイミド、ポリアミドイミド、エチレン−プロピレン−ジエンゴム（ＥＰＤＭ）、ブチルゴム、天然ゴム、ポリイソプレン、ポリエーテルイミド等の熱可塑性樹脂が挙げられる。また、オイルとしては例えば、シリコーンオイル、フルオロエーテルオイル、鉱物油、動植物性天然油、パラフィン等が挙げられる。これらの樹脂やオイルは、１種を単独で使用しても２種以上を併用してもよい。 As the matrix in such a thermosetting composite material of the present invention, an insulating resin or an insulating oil is preferably used, and there is no particular limitation, but the resin is, for example, an epoxy resin or a phenol resin. , Thermosetting resins such as silicone resins, polystyrene, polymethylmethacrylate, polycarbonate, polyolefins (eg polyethylene, polypropylene), polyolefin elastomers, polyethylene terephthalates, nylons, ABS resins, polyamides, polyimides, polyamideimides, ethylene-propylene- Examples thereof include thermoplastic resins such as diene rubber (EPDM), butyl rubber, natural rubber, polystyrene, and polyetherimide. Examples of the oil include silicone oil, fluoroether oil, mineral oil, animal and vegetable natural oil, paraffin and the like. These resins and oils may be used alone or in combination of two or more.
本発明の熱伝導性複合材料においては、その断面基準で、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積が、前記複合材料の断面面積に対して１〜５０％となっていることが必要である。前記膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率が１％未満では、複合材料中で窒化ホウ素微粒子間の接触部位を通じて熱が拡散する熱伝導パスのネットワーク構造が十分に形成されず、得られる複合材料の熱伝導性が十分に向上しない。一方、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率が５０％を超えると、複合材料にする際にフィラーがかさ高くなって取り扱いが困難となる。また、複合材料の熱伝導性がより向上するという観点から、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率が、前記複合材料の断面面積に対して５〜４５％であることが好ましく、１０〜４０％であることがより好ましく、１５〜３５％であることが特に好ましい。 In the thermally conductive composite material of the present invention, it is necessary that the total area of the region corresponding to the swollen boron nitride fine particles is 1 to 50% of the cross-sectional area of the composite material based on the cross section. Is. If the ratio of the total area of the region corresponding to the swollen boron nitride fine particles is less than 1%, the network structure of the heat conduction path in which heat is diffused through the contact site between the boron nitride fine particles in the composite material is not sufficiently formed. The thermal conductivity of the composite material is not sufficiently improved. On the other hand, if the ratio of the total area of the region corresponding to the swollen boron nitride fine particles exceeds 50%, the filler becomes bulky when the composite material is formed, which makes handling difficult. Further, from the viewpoint of further improving the thermal conductivity of the composite material, the ratio of the total area of the region corresponding to the swollen boron nitride fine particles is preferably 5 to 45% with respect to the cross-sectional area of the composite material. , 10-40% is more preferable, and 15-35% is particularly preferable.
なお、複合材料の断面基準で、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率（前記複合材料の断面面積に対する比率）は、以下のようにして求められる。すなわち、前述のとおり、複合材料の断面の走査型電子顕微鏡写真（ＳＥＭ像）において、明度と形状に基づいて、
（ｉ）前記膨潤窒化ホウ素微粒子（前記部分劈開窒化ホウ素微粒子とその劈開空隙に取り込まれたマトリックス）に相当する領域と、
（ｉｉ）前記非膨潤窒化ホウ素微粒子（前記未劈開窒化ホウ素粒子及び前記完全劈開窒化ホウ素微粒子）に相当する領域と、
（ｉｉｉ）マトリックスのうち前記膨潤窒化ホウ素微粒子中に取り込まれずに存在するマトリックスに相当する領域と、
を区別して認識し、公知の二値化等の画像解析手法によりそれぞれの領域の面積を求めることができる。したがって、複合材料の断面について、例えば、横６０μｍ以上、縦４０μｍ以上の測定領域を任意に１０箇所以上抽出し、それぞれの測定領域のＳＥＭ像において（ｉ）前記膨潤窒化ホウ素微粒子に相当する領域の合計面積を求め、当該測定領域の面積に対する比率として当該領域における前記膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率を求めることができる。そして、全ての測定領域の平均値を算出することにより、測定対象の熱伝導性複合材料について、その断面基準で、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率（前記複合材料の断面面積に対する比率、平均値）が求められる。
The ratio of the total area of the region corresponding to the swollen boron nitride fine particles (ratio to the cross-sectional area of the composite material) is obtained as follows on the basis of the cross section of the composite material. That is, as described above, in a scanning electron micrograph (SEM image) of a cross section of a composite material, based on brightness and shape,
(I) A region corresponding to the swollen boron nitride fine particles (the partially cleaved boron nitride fine particles and the matrix incorporated in the cleaved voids).
(Ii) A region corresponding to the non-cleavage boron nitride fine particles (the uncleavage boron nitride particles and the fully cleaved boron nitride fine particles), and
(Iii) A region of the matrix corresponding to the matrix that exists without being incorporated into the swollen boron nitride fine particles.
Can be distinguished and recognized, and the area of each region can be obtained by a known image analysis method such as binarization. Therefore, with respect to the cross section of the composite material, for example, 10 or more measurement regions having a width of 60 μm or more and a length of 40 μm or more are arbitrarily extracted, and in the SEM image of each measurement region, (i) the region corresponding to the swollen boron nitride fine particles. The total area can be obtained, and the ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the region can be obtained as the ratio to the area of the measurement region. Then, by calculating the average value of all the measurement regions, the ratio of the total area of the regions corresponding to the swollen boron nitride fine particles (cross section of the composite material) of the thermally conductive composite material to be measured is based on the cross section. Ratio to area, average value) is obtained.
本発明の熱伝導性複合材料においては、前記熱伝導性フィラーの含有率が前記複合材料の全量に対して１０〜９０体積％であることが好ましく、１５〜８０体積％であることがより好ましく、２０〜７０体積％であることが特に好ましい。前記熱伝導性フィラーの含有率が前記下限未満では、複合材料中で窒化ホウ素微粒子（前記高熱伝導性微粒子を含有する場合は前記窒化ホウ素微粒子及び前記高熱伝導性微粒子）間の接触部位を通じて熱が拡散する熱伝導パスのネットワーク構造が十分に形成されず、得られる複合材料の熱伝導性が十分に向上しない傾向にある。一方、前記熱伝導性フィラーの含有率が前記上限を超えると、膨潤窒化ホウ素微粒子領域にマトリックスが十分に浸透せず、空隙が生じやすくなり、フィラーの部分劈開による高熱伝導化の効果が相殺されてしまい、また、粒子同士の立体的な干渉により充填率が低下してしまう傾向にある。 In the thermally conductive composite material of the present invention, the content of the thermally conductive filler is preferably 10 to 90% by volume, more preferably 15 to 80% by volume, based on the total amount of the composite material. It is particularly preferably 20 to 70% by volume. When the content of the heat conductive filler is less than the lower limit, heat is generated through the contact portion between the boron nitride fine particles (in the case where the high heat conductive fine particles are contained, the boron nitride fine particles and the high heat conductive fine particles) in the composite material. The network structure of the diffusing heat conduction path is not sufficiently formed, and the heat conductivity of the obtained composite material tends not to be sufficiently improved. On the other hand, when the content of the thermally conductive filler exceeds the upper limit, the matrix does not sufficiently permeate into the swollen boron nitride fine particle region, and voids are likely to occur, and the effect of high thermal conductivity due to partial cleavage of the filler is offset. In addition, the filling rate tends to decrease due to the three-dimensional interference between the particles.
次に、本発明の熱伝導性フィラーの製造方法及び本発明の熱伝導性複合材料の製造方法について説明する。 Next, the method for producing the thermally conductive filler of the present invention and the method for producing the thermally conductive composite material of the present invention will be described.
先ず、本発明の熱伝導性フィラーの製造方法（本発明の熱伝導性複合材料の製造方法の前段工程）においては、窒化ホウ素粒子を含有する流体を高圧でノズルから噴射させて湿式衝突粉砕することにより、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子を含む窒化ホウ素微粒子からなる熱伝導性フィラーを得る（湿式粉砕工程）。 First, in the method for producing a thermally conductive filler of the present invention (the first step of the method for producing a thermally conductive composite material of the present invention), a fluid containing boron nitride particles is injected from a nozzle at a high pressure to perform wet collision pulverization. As a result, a thermally conductive filler composed of boron nitride fine particles containing the partially opened boron nitride fine particles in which the boron nitride fine particles are partially opened is obtained (wet grinding step).
このような本発明にかかる湿式粉砕工程においては、原料粒子としての窒化ホウ素粒子を含有する流体を高圧でノズルから噴射させることにより、粒子同士が衝突あるいはせん断流動により微細化することによって結晶構造の破壊や過度の微細化を抑制しつつ湿式粉砕されるとともに、粒子が流体中で高圧でせん断流動圧縮させた状態から急激に圧力を低下させることにより、粒子に対して加わっていた圧力が急激に消失することで粒子内部から外部に向かって膨張する力が働き、それに伴って粒子が外側に引っ張られることによって粒子の内部や端部に部分的な劈開が生じて前述の部分劈開窒化ホウ素微粒子が得られるようになる。 In such a wet pulverization step according to the present invention, a fluid containing boron nitride particles as raw material particles is injected from a nozzle at a high pressure, so that the particles collide with each other or become finer due to shear flow to form a crystal structure. Wet pulverization while suppressing fracture and excessive micronization, and the pressure applied to the particles suddenly decreases from the state where the particles are sheared, flowed and compressed at high pressure in the fluid. When the particles disappear, a force that expands from the inside to the outside of the particles acts, and the particles are pulled outward accordingly, causing partial opening inside and at the ends of the particles, resulting in the above-mentioned partially opened boron nitride fine particles. You will be able to obtain it.
このような湿式粉砕工程に用いる装置としては、特に制限されず、原料粒子を含有する流体を高圧でノズルから噴射させて湿式衝突粉砕させて微細化する原理に基づく市販の湿式粉砕装置（湿式微細化装置）を用いることができる。また、窒化ホウ素粒子の結晶構造の破壊や過度の微細化を抑制しつつ湿式粉砕するという観点から、ストレート型のノズルを備える湿式粉砕装置を用いることが好ましい。 The apparatus used in such a wet pulverization step is not particularly limited, and is a commercially available wet pulverizer (wet pulverization) based on the principle of injecting a fluid containing raw material particles from a nozzle at high pressure to perform wet collision pulverization to make the particles finer. A device) can be used. Further, from the viewpoint of wet pulverization while suppressing destruction of the crystal structure of the boron nitride particles and excessive miniaturization, it is preferable to use a wet pulverizer provided with a straight nozzle.
また、原料粒子として用いる窒化ホウ素粒子も特に制限されず、目的とする窒化ホウ素微粒子の平均粒子径等に応じて、平均粒子径が２〜２００μｍ（より好ましくは１０〜６０μｍ）程度の市販の窒化ホウ素粉末（好ましくは六方晶系の板状窒化ホウ素粉末）を用いることができる。 Further, the boron nitride particles used as the raw material particles are not particularly limited, and commercially available boron nitride having an average particle diameter of about 2 to 200 μm (more preferably 10 to 60 μm) depends on the average particle diameter of the target boron nitride fine particles and the like. Boron powder (preferably hexagonal plate-shaped boron nitride powder) can be used.
また、前記窒化ホウ素粒子とともにノズルから噴射させる流体の分散媒も特に制限されず、例えば、水；Ｎ−メチル−２−ピロリドン、クロロホルム、ジクロロメタン、四塩化炭素、アセトン、メチルエチルケトン、メチルイソブチルケトン、ジイソブチルケトン、酢酸メチル、酢酸エチル、酢酸プロピル、酢酸イソプロピル、酢酸ブチル、酢酸イソブチル、酢酸ペンチル、酢酸イソペンチル、酢酸アミル、テトラヒドロフラン、ジメチルホルムアルデヒド、ジメチルアセトアミド、ジメチルスルホキシド、アセトニトリル、メタノール、エタノール、プロパノール、イソプロパノール、ブタノール、ヘキサノール、オクタノール、ヘキサフルオロイソプロパノール、エチレングリコール、プロピレングリコール、テトラメチレングリコール、テトラエチレングリコール、ヘキサメチレングリコール、ジエチレングリコール、ベンゼン、トルエン、キシレン、クロロベンゼン、ジクロロベンゼン、トリクロロベンゼン、クロロフェノール、フェノール、テトラヒドロフラン、スルホラン、１，３−ジメチル−２−イミダゾリジノン、γ−ブチロラクトン、Ｎ−ジメチルピロリドン、ペンタン、ヘキサン、ネオペンタン、シクロヘキサン、ヘプタン、オクタン、イソオクタン、ノナン、デカン、ジエチルエーテル等の有機溶媒；シリコーンオイル、流動パラフィン等のオイル類が挙げられる。 Further, the dispersion medium of the fluid jetted from the nozzle together with the boron nitride particles is not particularly limited, and for example, water; N-methyl-2-pyrrolidone, chloroform, dichloromethane, carbon tetrachloride, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl. Ketone, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, amyl acetate, tetrahydrofuran, dimethylformaldehyde, dimethylacetamide, dimethylsulfoxide, acetonitrile, methanol, ethanol, propanol, isopropanol, Butanol, hexanol, octanol, hexafluoroisopropanol, ethylene glycol, propylene glycol, tetramethylene glycol, tetraethylene glycol, hexamethylene glycol, diethylene glycol, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene, chlorophenol, phenol, tetrahydrofuran , Sulfolane, 1,3-dimethyl-2-imidazolidinone, γ-butylolactone, N-dimethylpyrrolidone, pentane, hexane, neopentane, cyclohexane, heptane, octane, isooctane, nonane, decane, diethyl ether and other organic solvents; Examples include oils and oils such as liquid paraffin.
さらに、前記窒化ホウ素粒子を含有する流体（分散液）の濃度も特に制限されないが、前記窒化ホウ素粒子の含有率が０．１〜２０体積％が好ましく、０．５〜１０体積％がより好ましい。前記分散液の濃度が前記下限未満では劈開窒化ホウ素微粒子の収率が小さくなる傾向にあり、他方、前記上限を超えると分散液の粘度が高くなり粉砕処理が困難となる傾向にある。 Further, the concentration of the fluid (dispersion liquid) containing the boron nitride particles is not particularly limited, but the content of the boron nitride particles is preferably 0.1 to 20% by volume, more preferably 0.5 to 10% by volume. .. If the concentration of the dispersion liquid is less than the lower limit, the yield of the cleavage boron nitride fine particles tends to be small, while if it exceeds the upper limit, the viscosity of the dispersion liquid tends to be high and the pulverization treatment tends to be difficult.
また、前記湿式粉砕処理の際の諸条件としては、特に制限されるものではないが、前記部分劈開窒化ホウ素微粒子が効率良く得られるという観点から、以下の諸条件が好ましい。
噴射前圧力：３０〜２５０ＭＰａ（より好ましくは５０〜２００ＭＰａ）
噴射後圧力：常圧
ノズル径：０．１〜０．５ｍｍ
流量：０．１〜７．０Ｌ／ｍｉｎ（より好ましくは０．５〜１．１Ｌ／ｍｉｎ）
ノズル噴射流速：２００〜８００ｍ／ｓ（より好ましくは３００〜７００ｍ／ｓ）。
The conditions for the wet pulverization treatment are not particularly limited, but the following conditions are preferable from the viewpoint of efficiently obtaining the partially cleaved boron nitride fine particles.
Pre-injection pressure: 30-250 MPa (more preferably 50-200 MPa)
Post-injection pressure: Normal pressure Nozzle diameter: 0.1 to 0.5 mm
Flow rate: 0.1 to 7.0 L / min (more preferably 0.5 to 1.1 L / min)
Nozzle injection flow velocity: 200 to 800 m / s (more preferably 300 to 700 m / s).
前記湿式粉砕処理における噴射前圧力や流量やノズル噴射流速が前記下限未満では、前記窒化ホウ素粒子の劈開が進行しにくくなり、前記部分劈開窒化ホウ素微粒子が十分に得られなくなる傾向にある。他方、前記湿式粉砕処理における噴射前圧力や流量やノズル噴射流速が前記上限を超えると、前記窒化ホウ素粒子の劈開が進行し過ぎてしまい、大半の窒化ホウ素粒子が劈開により完全に分割されて前記完全劈開窒化ホウ素微粒子となり、前記部分劈開窒化ホウ素微粒子が十分に得られなくなる傾向にある。 If the pre-injection pressure, the flow rate, or the nozzle injection flow velocity in the wet pulverization treatment is less than the lower limit, the cleavage of the boron nitride particles is difficult to proceed, and the partially cleaved boron nitride fine particles tend to be insufficiently obtained. On the other hand, if the pre-injection pressure, the flow rate, or the nozzle injection flow velocity in the wet pulverization treatment exceeds the upper limit, the boron nitride particles are opened too much, and most of the boron nitride particles are completely divided by the opening. Completely open boron nitride fine particles tend to be obtained, and the partially open boron nitride fine particles tend to be insufficiently obtained.
さらに、前記窒化ホウ素粒子に前記湿式粉砕処理を施す回数は１回でもよいが、前記窒化ホウ素粒子に前記湿式粉砕処理を繰り返し施して所望量の前記部分劈開窒化ホウ素微粒子を含む窒化ホウ素微粒子を得るようにしてもよい。このように前記湿式粉砕処理を繰り返し施す場合、その繰り返す回数（パス数）は２〜２０回（より好ましくは２〜１０回）程度が好ましい。湿式粉砕処理を繰り返す回数（パス数）が前記上限を超えると、前記窒化ホウ素粒子の劈開が進行し過ぎてしまい、大半の窒化ホウ素粒子が劈開により完全に分割されて前記完全劈開窒化ホウ素微粒子となり、前記部分劈開窒化ホウ素微粒子が十分に得られなくなる傾向にある。 Further, the number of times the wet pulverization treatment is applied to the boron nitride particles may be one time, but the wet pulverization treatment is repeatedly applied to the boron nitride particles to obtain boron nitride fine particles containing the desired amount of the partially opened boron nitride fine particles. You may do so. When the wet pulverization treatment is repeatedly performed in this way, the number of repetitions (number of passes) is preferably about 2 to 20 times (more preferably 2 to 10 times). If the number of times the wet pulverization process is repeated (the number of passes) exceeds the upper limit, the cleavage of the boron nitride particles progresses too much, and most of the boron nitride particles are completely divided by the cleavage to become the completely open boron nitride fine particles. , The partial cleavage boron nitride fine particles tend to be insufficiently obtained.
前記湿式粉砕工程においては、前記湿式粉砕処理の後に、必要に応じてろ過、洗浄、及び乾燥処理を施して前記部分劈開窒化ホウ素微粒子を含む前記窒化ホウ素微粒子を得るが、かかるろ過、洗浄、及び乾燥処理としてはいずれも特に制限されず、公知の方法を適宜採用することができる。 In the wet pulverization step, after the wet pulverization treatment, if necessary, filtration, washing, and drying treatment are performed to obtain the boron nitride fine particles containing the partially opened boron nitride fine particles, which are filtered, washed, and dried. The drying treatment is not particularly limited, and a known method can be appropriately adopted.
次に、本発明の熱伝導性複合材料の製造方法の後段工程においては、前記部分劈開窒化ホウ素微粒子を含む窒化ホウ素微粒子（前記高熱伝導性微粒子を含有する場合は前記窒化ホウ素微粒子及び前記高熱伝導性微粒子）からなる熱伝導性フィラーをマトリックス中に分散させて、前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子を含有する熱伝導性複合材料を得る（複合工程）。 Next, in the subsequent step of the method for producing the heat conductive composite material of the present invention, the boron nitride fine particles containing the partially opened boron nitride fine particles (when the high thermal conductive fine particles are contained, the boron nitride fine particles and the high thermal conductivity). A thermally conductive filler composed of (sexual fine particles) is dispersed in a matrix to obtain a thermally conductive composite material containing the expanded boron nitride fine particles in which the matrix is filled in the open voids of the partially opened boron nitride fine particles. (Composite process).
このような本発明にかかる複合工程においては、先ず、前記部分劈開窒化ホウ素微粒子を含む窒化ホウ素微粒子からなる熱伝導性フィラーとマトリックスとを混合する。その際、得られる複合材料中の熱伝導性フィラーの含有率が目的の含有率となるように熱伝導性フィラーとマトリックスとの混合割合を定める。また、熱伝導性フィラーとマトリックスとを混合する方法は特に制限されず、公知の混合方法が適宜用いられる。 In such a composite step according to the present invention, first, a thermally conductive filler made of boron nitride fine particles containing the partially cleaved boron nitride fine particles and a matrix are mixed. At that time, the mixing ratio of the heat conductive filler and the matrix is determined so that the content of the heat conductive filler in the obtained composite material becomes the desired content. Further, the method of mixing the thermally conductive filler and the matrix is not particularly limited, and a known mixing method is appropriately used.
このようなマトリックスとして前記オイルを用いる場合は、前記熱伝導性フィラーと前記オイルとを混合して均一スラリーとすることにより前記熱伝導性複合材料を得ることができる。すなわち、このように前記熱伝導性フィラーと前記オイルとを混合する過程において、前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記オイルが入り込んで膨潤窒化ホウ素微粒子となり、前記膨潤窒化ホウ素微粒子を含有する熱伝導性複合材料が得られる。 When the oil is used as such a matrix, the heat conductive composite material can be obtained by mixing the heat conductive filler and the oil to form a uniform slurry. That is, in the process of mixing the thermally conductive filler and the oil in this way, the oil enters into the open voids of the partially opened boron nitride fine particles to become swollen boron nitride fine particles, and contains the swollen boron nitride fine particles. A thermally conductive composite material is obtained.
また、このようなマトリックスとして前記樹脂を用いる場合は、前記熱伝導性フィラーと前記樹脂とを混合して均一混合物とし、得られた混合物を成形することにより前記熱伝導性複合材料を得ることができる。すなわち、このように前記熱伝導性フィラーと前記樹脂とを混合及び成形する過程において、前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記樹脂が入り込んで膨潤窒化ホウ素微粒子となり、前記膨潤窒化ホウ素微粒子を含有する熱伝導性複合材料が得られる。 When the resin is used as such a matrix, the thermally conductive filler and the resin can be mixed to form a homogeneous mixture, and the obtained mixture can be molded to obtain the thermally conductive composite material. it can. That is, in the process of mixing and molding the thermally conductive filler and the resin in this way, the resin enters into the open voids of the partially opened boron nitride fine particles to become swollen boron nitride fine particles, and the swollen boron nitride fine particles are produced. A thermally conductive composite material containing the material is obtained.
このように前記熱伝導性フィラーと前記樹脂とを混合して均一混合物とする際に、分散媒を更に加えて均一スラリーとしてもよく、その場合は真空乾燥等の公知の方法で分散媒を除去した後に成形することが好ましい。このような分散媒としては特に制限されず、前記窒化ホウ素粒子とともにノズルから噴射させる流体の分散媒として挙げた有機溶媒と同様の有機溶媒を適宜用いてもよい。 When the thermally conductive filler and the resin are mixed in this way to form a homogeneous mixture, a dispersion medium may be further added to form a homogeneous slurry. In that case, the dispersion medium is removed by a known method such as vacuum drying. It is preferable to mold after The dispersion medium is not particularly limited, and an organic solvent similar to the organic solvent mentioned as the dispersion medium of the fluid jetted from the nozzle together with the boron nitride particles may be appropriately used.
また、前記混合物を成形する際に加圧して圧縮することが好ましい。このような圧縮方法としては特に制限されず、一軸圧縮であっても二軸圧縮であってもよい。また、静水圧で等方的に圧縮してもよい。また、圧縮時の圧力も特に制限はないが、５〜２０ＭＰａが好ましい。圧縮時の圧力が前記下限未満になると、得られる複合材料に空隙が残存しやすくなる傾向にあり、他方、前記上限を超えると、得られる複合材料内のフィラーの配向制御が困難となり、残留ひずみが発生する傾向にある。 Further, it is preferable to pressurize and compress the mixture when molding it. Such a compression method is not particularly limited, and may be uniaxial compression or biaxial compression. It may also be isotropically compressed with hydrostatic pressure. The pressure during compression is also not particularly limited, but is preferably 5 to 20 MPa. When the compression pressure is less than the lower limit, voids tend to remain in the obtained composite material, while when the pressure exceeds the upper limit, it becomes difficult to control the orientation of the filler in the obtained composite material, resulting in residual strain. Tends to occur.
さらに、前記混合物を成形する際に樹脂を固化させる方法としては特に制限はなく、公知の方法、例えば、樹脂として熱可塑性樹脂を用いた場合には放冷等の冷却による方法、各種（熱、光、水）硬化性樹脂を用いた場合にはそれぞれ適切な硬化方法を採用することができる。また、このような固化は、成形時又は成形後のいずれにおいて実施してもよい。 Further, the method for solidifying the resin when molding the mixture is not particularly limited, and a known method, for example, when a thermoplastic resin is used as the resin, a cooling method such as allowing to cool, various methods (heat, When a curable resin (light, water) is used, an appropriate curing method can be adopted for each. Moreover, such solidification may be carried out either at the time of molding or after molding.
以下、実施例および比較例に基づいて本発明をより具体的に説明するが、本発明は以下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 based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.
（実施例１）
原料粒子としての窒化ホウ素粒子としてデンカ株式会社製「デンカボロンナイトライド粉 ＳＧＰ」（平均粒子径：１８μｍ、六方晶板状窒化ホウ素（ＢＮ）粒子）を用い、Ｎ−メチル−２−ピロリドン（ＮＭＰ）を分散媒とする５体積％分散液を得た。次いで、市販のストレート型ノズルを備えた湿式粉砕装置を用い、噴射前のチャンバー内圧力を２００ＭＰａとし、前記窒化ホウ素粒子を含有する分散液をノズル（ノズル径：０．２ｍｍ）から流量１．０６９Ｌ／ｍｉｎ、流速６３２ｍ／ｓで噴射させ、高圧でせん断流動圧縮された状態から常圧まで急激に圧力を低下させることにより、１回目の湿式粉砕処理が施された分散液を得た。さらに、得られた分散液を再び同じ条件でノズルから噴射させる湿式粉砕処理を計１０回繰り返し（パス数：１０回）、湿式粉砕された窒化ホウ素微粒子を含有する分散液を得た。そして、得られた分散液から窒化ホウ素微粒子をろ過し、メタノールで洗浄した後に真空乾燥して、湿式粉砕された窒化ホウ素微粒子を得た。得られた窒化ホウ素微粒子の平均粒子径は５μｍであった。
(Example 1)
N-methyl-2-pyrrolidone (NMP) using "Denkaboron nitride powder SGP" (average particle size: 18 μm, hexagonal plate-shaped boron nitride (BN) particles) manufactured by Denka Co., Ltd. as boron nitride particles as raw material particles. ) Was used as a dispersion medium to obtain a 5% by volume dispersion. Next, using a commercially available wet pulverizer equipped with a straight nozzle, the pressure inside the chamber before injection was set to 200 MPa, and the dispersion liquid containing the boron nitride particles was discharged from the nozzle (nozzle diameter: 0.2 mm) at a flow rate of 1.069 L. The dispersion was subjected to the first wet pulverization treatment by injecting at a flow rate of 632 m / s at / min and rapidly reducing the pressure from a state of shear flow compression at high pressure to normal pressure. Further, the wet pulverization treatment of injecting the obtained dispersion liquid from the nozzle again under the same conditions was repeated 10 times in total (number of passes: 10 times) to obtain a dispersion liquid containing the wet pulverized boron nitride fine particles. Then, the boron nitride fine particles were filtered from the obtained dispersion, washed with methanol and then vacuum dried to obtain wet-pulverized boron nitride fine particles. The average particle size of the obtained boron nitride fine particles was 5 μm.
次いで、得られた窒化ホウ素微粒子を熱伝導性フィラーとし、一液熱硬化型エポキシ樹脂（セメダイン社製「エポキシ樹脂 ＥＰ１６０」）をマトリックスとして、以下のようにして複合材料を得た。すなわち、先ず、得られる複合材料中のフィラー（窒化ホウ素微粒子）含有率が４０体積％となるように、前記エポキシ樹脂のジクロロメタン溶液（濃度：６．０体積％）と前記窒化ホウ素微粒子とを混合し、得られたスラリーを撹拌しながらジクロロメタンを揮発させた後に約１５分真空乾燥してジクロロメタンを完全に除去して、前記窒化ホウ素微粒子が前記エポキシ樹脂中に分散した混合物を得た。次いで、得られた混合物を、１１０℃に予熱した円筒容器（内径：１４ｍｍφ）中に成形後の厚みが３５ｍｍとなるように充填し、円筒容器の長手方向に７．５ＭＰａの圧力で圧縮した状態で１１０℃に３０分維持してエポキシ樹脂を硬化せしめて円柱状の熱伝導性複合材料を得た。得られた複合材料の空隙率は０％であった。 Next, the obtained boron nitride fine particles were used as a heat conductive filler, and a one-component thermosetting epoxy resin (“epoxy resin EP160” manufactured by Semedyne Co., Ltd.) was used as a matrix to obtain a composite material as follows. That is, first, the dichloromethane solution (concentration: 6.0% by volume) of the epoxy resin and the boron nitride fine particles are mixed so that the filler (boron nitride fine particles) content in the obtained composite material is 40% by volume. After volatilizing dichloromethane while stirring the obtained slurry, the mixture was vacuum-dried for about 15 minutes to completely remove dichloromethane to obtain a mixture in which the boron nitride fine particles were dispersed in the epoxy resin. Next, the obtained mixture was filled in a cylindrical container (inner diameter: 14 mmφ) preheated to 110 ° C. so that the thickness after molding was 35 mm, and compressed at a pressure of 7.5 MPa in the longitudinal direction of the cylindrical container. The epoxy resin was cured by maintaining the temperature at 110 ° C. for 30 minutes to obtain a columnar heat conductive composite material. The porosity of the obtained composite material was 0%.
＜熱伝導率測定＞
図１に示すように、円柱状の複合材料１から熱伝導率測定用試料２（ｘ軸方向長さ：３ｍｍ、ｙ軸方向長さ：１０ｍｍ、ｚ軸方向長さ：１０ｍｍ）を切り出し、前記試料の厚さ方向（ｘ軸方向）を熱流方向としてキセノンフラッシュアナライザー（ＮＥＴＺＳＣＨ社製「ＬＦＡ ４４７ ＮａｎｏＦｌａｓｈ」）を用いて圧縮方向に垂直な方向（ｘ軸方向）の熱拡散率を測定した。
<Measurement of thermal conductivity>
As shown in FIG. 1, a sample 2 for measuring thermal conductivity (length in the x-axis direction: 3 mm, length in the y-axis direction: 10 mm, length in the z-axis direction: 10 mm) was cut out from the columnar composite material 1 and described above. The thermal diffusivity in the direction perpendicular to the compression direction (x-axis direction) was measured using a xenon flash analyzer (“LFA 447 NanoFlash” manufactured by NETZSCH) with the thickness direction (x-axis direction) of the sample as the heat flow direction.
また、前記試料の比熱を熱振動型示差走査熱量測定装置（ティー・エイ・インスツル社製）を用いてＤＳＣ法により測定した。さらに、前記試料の密度を水中置換法（アルキメデス法）により求めた。これらの結果から次式：
熱伝導率（Ｗ／（ｍ・Ｋ））＝比熱（Ｊ／（ｋｇ・Ｋ））×密度（ｋｇ／ｍ３）×熱拡散率（ｍ２／秒）
により、圧縮方向に垂直な方向（ｘ軸方向）の熱伝導率を求めた。得られた結果を表２に示す。
Further, the specific heat of the sample was measured by the DSC method using a thermal vibration type differential scanning calorimetry device (manufactured by TA Instruments). Further, the density of the sample was determined by an underwater substitution method (Archimedes method). From these results, the following equation:
Thermal conductivity (W / (m · K)) = specific heat (J / (kg · K)) x density (kg / m 3 ) x thermal diffusivity (m 2 / sec)
The thermal conductivity in the direction perpendicular to the compression direction (x-axis direction) was obtained. The results obtained are shown in Table 2.
＜断面の電子顕微鏡観察及び構造解析＞
円柱状の複合材料から断面の電子顕微鏡観察用の試料を切り出し、任意の１０箇所の断面測定領域（実施例１においては縦２１０ミクロン、横７０ミクロンの領域）について研磨機（ビューラー社製「ミニメットＴＭ１０００」）を用いて機械研磨を施した後に走査型電子顕微鏡（（株）日立ハイテクノロジーズ製「ＮＢ−５０００」）を用いて断面の電子顕微鏡観察を行った。得られた走査型電子顕微鏡写真（ＳＥＭ像）の一例を図２に示す。
<Electron microscope observation and structural analysis of cross section>
A sample for electron microscope observation of the cross section is cut out from the columnar composite material, and a polishing machine (Buehler's "Minimet") is used for arbitrary 10 cross section measurement regions (210 microns in length and 70 microns in width in Example 1). After mechanical polishing using TM 1000 "), cross-sectional electron microscope observation was performed using a scanning electron microscope ("NB-5000" manufactured by Hitachi High-Technologies Corporation). An example of the obtained scanning electron micrograph (SEM image) is shown in FIG.
次いで、得られた各測定領域のＳＥＭ像において、明度と形状に基づいて、
（ｉ）膨潤窒化ホウ素微粒子（部分劈開窒化ホウ素微粒子とその劈開空隙に取り込まれたマトリックス）に相当する領域と、
（ｉｉ）非膨潤窒化ホウ素微粒子（未劈開窒化ホウ素粒子及び完全劈開窒化ホウ素微粒子）に相当する領域と、
（ｉｉｉ）マトリックスのうち前記膨潤窒化ホウ素微粒子中に取り込まれずに存在するマトリックスに相当する領域と、
を区別して認識し、二値化により（ｉ）膨潤窒化ホウ素微粒子に相当する領域の合計面積を求め、当該測定領域の面積に対する比率として当該領域における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率を求めた。そして、全ての測定領域の平均値を算出することにより、得られた複合材料における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率（前記複合材料の断面面積に対する比率、平均値）を求めた。得られた結果を表２に示す。また、二値化により、（ｉ）膨潤窒化ホウ素微粒子に相当する領域以外の領域、すなわち（ｉｉ）非膨潤窒化ホウ素微粒子に相当する領域及び（ｉｉｉ）マトリックスのうち前記膨潤窒化ホウ素微粒子中に取り込まれずに存在するマトリックスに相当する領域、を濃色に着色したＳＥＭ像の一例を図３に示す。
Then, in the obtained SEM image of each measurement region, based on the brightness and shape,
(I) A region corresponding to swollen boron nitride fine particles (partially cleaved boron nitride fine particles and a matrix incorporated into the cleaved voids) and
(Ii) Regions corresponding to non-cleavage boron nitride fine particles (uncleavage boron nitride particles and fully cleaved boron nitride fine particles), and
(Iii) A region of the matrix corresponding to the matrix that exists without being incorporated into the swollen boron nitride fine particles.
(I) Obtain the total area of the region corresponding to the swollen boron nitride fine particles by binarization, and calculate the total area of the region corresponding to the swollen boron nitride fine particles in the region as a ratio to the area of the measurement region. The ratio was calculated. Then, by calculating the average value of all the measurement regions, the ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the obtained composite material (ratio to the cross-sectional area of the composite material, the average value) was obtained. .. The results obtained are shown in Table 2. Further, by binarization, the region other than the region corresponding to the (i) swollen boron nitride fine particles, that is, the region corresponding to the (ii) non-swelled boron nitride fine particles and the (iii) matrix are incorporated into the swollen boron nitride fine particles. FIG. 3 shows an example of an SEM image in which the region corresponding to the matrix that exists without any particles is darkly colored.
また、得られた各測定領域のＳＥＭ像において、同様に二値化により（ｉｉ）非膨潤窒化ホウ素微粒子（未劈開窒化ホウ素粒子及び完全劈開窒化ホウ素微粒子）に相当する領域の合計面積を求め、当該測定領域における全ての窒化ホウ素が未劈開窒化ホウ素粒子である場合の全窒化ホウ素粒子に相当する領域の合計面積（後述する比較例１における同一面積の測定領域における非膨潤窒化ホウ素微粒子に相当する領域の合計面積）との関係から、当該領域における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率を求めた。そして、全ての測定領域の平均値を算出することにより、得られた複合材料に用いたフィラーにおける窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率（平均値）を求めた。得られた結果を表２に示す。 Further, in the obtained SEM image of each measurement region, the total area of the region corresponding to (ii) non-swelling boron nitride fine particles (unexpanded boron nitride particles and completely open boron nitride fine particles) was obtained by binarization in the same manner. The total area of the region corresponding to the total boron nitride particles when all the boron nitride in the measurement region is unopened boron nitride particles (corresponding to the non-swelling boron nitride fine particles in the measurement region of the same area in Comparative Example 1 described later). From the relationship with the total area of the region), the content of the partially opened boron nitride fine particles with respect to the total amount of the boron nitride fine particles in the region was determined. Then, by calculating the average value of all the measurement regions, the content (average value) of the partially cleaved boron nitride fine particles with respect to the total amount of the boron nitride fine particles in the filler used in the obtained composite material was obtained. The results obtained are shown in Table 2.
（比較例１）
実施例１において原料粒子として用いた窒化ホウ素粒子を、湿式粉砕することなくそのまま熱伝導性フィラーとして用いるようにしたこと以外は実施例１と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例１と同様にして熱伝導率測定を行い、圧縮方向に垂直な方向（ｘ軸方向）の熱伝導率を求めた。得られた結果を表２に示す。
(Comparative Example 1)
A thermally conductive composite material was obtained in the same manner as in Example 1 except that the boron nitride particles used as the raw material particles in Example 1 were used as they were as a thermally conductive filler without wet pulverization. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 1, and the thermal conductivity in the direction perpendicular to the compression direction (x-axis direction) was determined. The results obtained are shown in Table 2.
また、得られた複合材料について実施例１と同様にして断面の電子顕微鏡観察及び構造解析を行い、得られた複合材料における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率、並びに、用いたフィラーおける部分劈開窒化ホウ素微粒子の含有率を求めた。得られた結果を表２に示す。また、得られた走査型電子顕微鏡写真（ＳＥＭ像）の一例を図４に示す。さらに、二値化により非膨潤窒化ホウ素粒子に相当する領域を濃色に着色したＳＥＭ像の一例を図５に示す。 Further, the obtained composite material was subjected to electron microscope observation and structural analysis of the cross section in the same manner as in Example 1, and the ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the obtained composite material and the ratio of the total area were used. The content of the partially opened boron nitride fine particles in the filler was determined. The results obtained are shown in Table 2. Further, an example of the obtained scanning electron micrograph (SEM image) is shown in FIG. Further, FIG. 5 shows an example of an SEM image in which the region corresponding to the non-swelling boron nitride particles is darkly colored by binarization.
（比較例２）
窒化ホウ素粒子としてデンカ株式会社製「デンカボロンナイトライド粉 ＳＧＰ」（平均粒子径：１８μｍ）に代えてデンカ株式会社製「デンカボロンナイトライド粉 ＨＧＰ」（平均粒子径：５μｍ、六方晶板状窒化ホウ素（ＢＮ）粒子）を用いるようにしたこと以外は比較例１と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例１と同様にして熱伝導率測定を行い、圧縮方向に垂直な方向（ｘ軸方向）の熱伝導率を求めた。得られた結果を表２に示す。
(Comparative Example 2)
As boron nitride particles, "Dencaboron nitride powder SGP" (average particle size: 18 μm) manufactured by Denka Co., Ltd. is replaced with "Dencaboron nitride powder HGP" (average particle size: 5 μm, hexagonal plate-like nitrided) manufactured by Denka Co., Ltd. A thermally conductive composite material was obtained in the same manner as in Comparative Example 1 except that boron (BN) particles) were used. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 1, and the thermal conductivity in the direction perpendicular to the compression direction (x-axis direction) was determined. The results obtained are shown in Table 2.
また、得られた複合材料について実施例１と同様にして断面の電子顕微鏡観察及び構造解析を行い、得られた複合材料における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率、並びに、用いたフィラーおける部分劈開窒化ホウ素微粒子の含有率を求めた。得られた結果を表２に示す。 Further, the obtained composite material was subjected to electron microscope observation and structural analysis of the cross section in the same manner as in Example 1, and the ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the obtained composite material and the ratio of the total area were used. The content of the partially opened boron nitride fine particles in the filler was determined. The results obtained are shown in Table 2.
（実施例２）
原料粒子としての窒化ホウ素粒子としてデンカ株式会社製「デンカボロンナイトライド粉 ＳＧＰ」（平均粒子径：１８μｍ）に代えてモメンティブ社製「窒化ホウ素（ＢＮ）パウダー ＰＴ１１０」（平均粒子径：４０μｍ、六方晶板状窒化ホウ素（ＢＮ）粒子）を用いるようにしたこと以外は実施例１と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例１と同様にして熱伝導率測定を行い、圧縮方向に垂直な方向（ｘ軸方向）の熱伝導率を求めた。得られた結果を表２に示す。
(Example 2)
As boron nitride particles as raw material particles, "Dencaboron Nitride Powder SGP" (average particle size: 18 μm) manufactured by Denka Co., Ltd. is replaced with "Boron Nitride (BN) Powder PT110" manufactured by Momentive Co., Ltd. (average particle size: 40 μm, hexagonal). A thermally conductive composite material was obtained in the same manner as in Example 1 except that the crystal plate-shaped boron nitride (BN) particles were used. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 1, and the thermal conductivity in the direction perpendicular to the compression direction (x-axis direction) was determined. The results obtained are shown in Table 2.
また、得られた複合材料について、断面測定領域を縦６０ミクロン、横４０ミクロンの領域としたこと以外は実施例１と同様にして断面の電子顕微鏡観察及び構造解析を行い、得られた複合材料における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率、並びに、用いたフィラーにおける部分劈開窒化ホウ素微粒子の含有率を求めた。得られた結果を表２に示す。 Further, with respect to the obtained composite material, the cross section was observed and structurally analyzed by an electron microscope in the same manner as in Example 1 except that the cross-sectional measurement region was set to a region of 60 microns in length and 40 microns in width, and the obtained composite material was obtained. The ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the above, and the content of the partially opened boron nitride fine particles in the filler used were determined. The results obtained are shown in Table 2.
（実施例３〜４）
湿式粉砕処理における諸条件を表１に示すように変更したこと以外は実施例２と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例１と同様にして熱伝導率測定を行い、圧縮方向に垂直な方向（ｘ軸方向）の熱伝導率を求めた。得られた結果を表２に示す。
(Examples 3 to 4)
A thermally conductive composite material was obtained in the same manner as in Example 2 except that the conditions in the wet pulverization treatment were changed as shown in Table 1. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 1, and the thermal conductivity in the direction perpendicular to the compression direction (x-axis direction) was determined. The results obtained are shown in Table 2.
また、得られた複合材料について、断面測定領域を縦６０ミクロン、横４０ミクロンの領域としたこと以外は実施例１と同様にして断面の電子顕微鏡観察及び構造解析を行い、得られた複合材料における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率、並びに、用いたフィラーにおける部分劈開窒化ホウ素微粒子の含有率を求めた。得られた結果を表２に示す。 Further, with respect to the obtained composite material, the cross section was observed and structurally analyzed by an electron microscope in the same manner as in Example 1 except that the cross-sectional measurement region was set to a region of 60 microns in length and 40 microns in width, and the obtained composite material was obtained. The ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the above, and the content of the partially opened boron nitride fine particles in the filler used were determined. The results obtained are shown in Table 2.
（比較例３）
実施例２において原料粒子として用いた窒化ホウ素粒子を、湿式粉砕することなくそのまま熱伝導性フィラーとして用いるようにしたこと以外は実施例２と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例１と同様にして熱伝導率測定を行い、圧縮方向に垂直な方向（ｘ軸方向）の熱伝導率を求めた。得られた結果を表２に示す。
(Comparative Example 3)
A thermally conductive composite material was obtained in the same manner as in Example 2 except that the boron nitride particles used as the raw material particles in Example 2 were used as they were as a thermally conductive filler without wet pulverization. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 1, and the thermal conductivity in the direction perpendicular to the compression direction (x-axis direction) was determined. The results obtained are shown in Table 2.
また、得られた複合材料について、断面測定領域を縦６０ミクロン、横４０ミクロンの領域としたこと以外は実施例１と同様にして断面の電子顕微鏡観察及び構造解析を行い、得られた複合材料における膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率、並びに、用いたフィラーにおける部分劈開窒化ホウ素微粒子の含有率を求めた。得られた結果を表２に示す。 Further, with respect to the obtained composite material, the cross section was observed and structurally analyzed by an electron microscope in the same manner as in Example 1 except that the cross-sectional measurement region was set to a region of 60 microns in length and 40 microns in width, and the obtained composite material was obtained. The ratio of the total area of the region corresponding to the swollen boron nitride fine particles in the above, and the content of the partially opened boron nitride fine particles in the filler used were determined. The results obtained are shown in Table 2.
＜表１及び表２に示した結果の評価＞
表１及び表２に示した結果から明らかな通り、本発明の熱伝導性フィラーの製造方法により得られた実施例１〜４の熱伝導性フィラーにおいては、いずれも部分劈開窒化ホウ素微粒子の含有率が窒化ホウ素微粒子の全量に対して５体積％以上のものであった。それに対して、本発明にかかる湿式粉砕処理を施していない市販の窒化ホウ素粒子においては、いずれも部分劈開窒化ホウ素微粒子は含有されていないことが確認された。
<Evaluation of the results shown in Tables 1 and 2>
As is clear from the results shown in Tables 1 and 2, the thermally conductive fillers of Examples 1 to 4 obtained by the method for producing the thermally conductive filler of the present invention all contain partially cleaved boron nitride fine particles. The ratio was 5% by volume or more based on the total amount of the boron nitride fine particles. On the other hand, it was confirmed that none of the commercially available boron nitride particles subjected to the wet pulverization treatment according to the present invention contained the partially cleaved boron nitride fine particles.
さらに、前記のように部分劈開窒化ホウ素微粒子を含有する本発明の熱伝導性フィラーを用いて本発明の熱伝導性複合材料の製造方法により得られた実施例１〜４の熱伝導性複合材料においては、いずれも複合材料の断面基準で膨潤窒化ホウ素微粒子に相当する領域の合計面積が複合材料の断面面積に対して１〜５０％の範囲内にあり、このような本発明の熱伝導性複合材料は、膨潤窒化ホウ素微粒子の存在が確認されない比較例１〜３の熱伝導性複合材料に比べて熱伝導率が非常に高いことが確認された。 Further, as described above, the thermally conductive composite material of Examples 1 to 4 obtained by the method for producing the thermally conductive composite material of the present invention using the thermally conductive filler of the present invention containing the partially open boron nitride fine particles. In each case, the total area of the region corresponding to the swollen boron nitride fine particles is in the range of 1 to 50% with respect to the cross-sectional area of the composite material based on the cross-sectional area of the composite material, and the thermal conductivity of the present invention is such. It was confirmed that the composite material has a much higher thermal conductivity than the heat conductive composite materials of Comparative Examples 1 to 3 in which the presence of swollen boron nitride fine particles was not confirmed.
（実施例５）
熱伝導性フィラーとして、実施例２において得られた湿式粉砕された窒化ホウ素微粒子と、窒化アルミニウム微粒子（巴工業株式会社製「窒化アルミ（ＡｌＮ）パウダー」、平均粒子径：１０μｍ）とを用い、得られる複合材料中の粉砕窒化ホウ素微粒子及び窒化アルミニウム微粒子の含有率がそれぞれ３２体積％及び８体積％となるように混合して用いるようにしたこと以外は実施例２と同様にして熱伝導性複合材料を得た。
(Example 5)
As the heat conductive filler, the wet-pulverized boron nitride fine particles obtained in Example 2 and aluminum nitride fine particles (“aluminum nitride (AlN) powder” manufactured by Tomoe Kogyo Co., Ltd., average particle diameter: 10 μm) were used. Thermal conductivity is the same as in Example 2 except that the crushed boron nitride fine particles and aluminum nitride fine particles in the obtained composite material are mixed and used so as to be 32% by volume and 8% by volume, respectively. A composite material was obtained.
次いで、得られた円柱状の複合材料１から熱伝導率測定用試料（ｚ軸方向厚さ：２ｍｍ、直径：１４ｍｍφ、図示せず）を切り出し、前記試料の厚さ方向（ｚ軸方向）を熱流方向としてキセノンフラッシュアナライザー（ＮＥＴＺＳＣＨ社製「ＬＦＡ ４４７ ＮａｎｏＦｌａｓｈ」）を用いて圧縮方向に平行な方向（ｚ軸方向）の熱拡散率を測定し、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。 Next, a sample for measuring thermal conductivity (thickness in the z-axis direction: 2 mm, diameter: 14 mmφ, not shown) was cut out from the obtained columnar composite material 1, and the thickness direction (z-axis direction) of the sample was determined. As the heat flow direction, a xenon flash analyzer ("LFA 447 NanoFlash" manufactured by NETZSCH) is used to measure the thermal conductivity in the direction parallel to the compression direction (z-axis direction), and the direction parallel to the compression direction (z-axis direction). The thermal conductivity was calculated. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例２で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 2 (the latter is proportional to the content of boron nitride fine particles).
（比較例４）
実施例２において得られた湿式粉砕された窒化ホウ素微粒子に代えて比較例３において用いた未粉砕の窒化ホウ素粒子を用いるようにしたこと以外は実施例５と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Comparative Example 4)
The thermally conductive composite material was prepared in the same manner as in Example 5 except that the unpulverized boron nitride particles used in Comparative Example 3 were used instead of the wet-pulverized boron nitride fine particles obtained in Example 2. Obtained. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
（実施例６）
湿式粉砕処理における諸条件を表１に示すように変更し、さらに得られる複合材料中のフィラー（窒化ホウ素微粒子）含有率が６０体積％となるようにしたこと以外は実施例２と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 6)
The conditions in the wet pulverization treatment were changed as shown in Table 1, and the filler (boron nitride fine particles) content in the obtained composite material was changed to 60% by volume in the same manner as in Example 2. A thermally conductive composite material was obtained. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料について、断面測定領域を縦６０ミクロン、横４０ミクロンの領域としたこと以外は実施例１と同様にして断面の電子顕微鏡観察及び構造解析を行い、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］を求めたところ、それぞれ３２．１体積％及び４４．７％であった。 Further, with respect to the obtained composite material, the cross-section was observed and structurally analyzed in the same manner as in Example 1 except that the cross-sectional measurement region was set to a region of 60 microns in length and 40 microns in width, and the obtained composite material was obtained. The content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the above and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material were determined. It was 1 volume% and 44.7%.
（実施例７）
熱伝導性フィラーとして、実施例６において得られた湿式粉砕された窒化ホウ素微粒子と、窒化アルミニウム微粒子（株式会社トクヤマ製「窒化アルミニウム（ＡｌＮ）粉末 Ｅグレード」、平均粒子径：１μｍ）とを用い、得られる複合材料中の粉砕窒化ホウ素微粒子及び窒化アルミニウム微粒子の含有率がそれぞれ４８体積％及び１２体積％となるように混合して用いるようにしたこと以外は実施例６と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 7)
As the heat conductive filler, the wet pulverized boron nitride fine particles obtained in Example 6 and aluminum nitride fine particles (“Aluminum Nitride (AlN) Powder E Grade” manufactured by Tokuyama Co., Ltd., average particle diameter: 1 μm) were used. , Heat conduction in the same manner as in Example 6 except that the crushed boron nitride fine particles and the aluminum nitride fine particles in the obtained composite material were mixed and used so as to be 48% by volume and 12% by volume, respectively. A sex composite material was obtained. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例６で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 6 (the latter is proportional to the content of boron nitride fine particles).
（比較例５）
熱伝導性フィラーとして前記窒化アルミニウム微粒子（平均粒子径：１μｍ）のみを用い、得られる複合材料中の窒化アルミニウム微粒子の含有率が６０体積％となるようにしたこと以外は実施例７と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Comparative Example 5)
The same as in Example 7 except that only the aluminum nitride fine particles (average particle diameter: 1 μm) were used as the heat conductive filler and the content of the aluminum nitride fine particles in the obtained composite material was 60% by volume. Obtained a thermally conductive composite material. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
（実施例８）
熱伝導性フィラーとして、実施例６において得られた湿式粉砕された窒化ホウ素微粒子と、窒化アルミニウム微粒子（古河電子株式会社製「高熱伝導ＡｌＮフィラー ＦＡＮ−ｆ０５」、平均粒子径：５μｍ）とを用い、得られる複合材料中の粉砕窒化ホウ素微粒子及び窒化アルミニウム微粒子の含有率がそれぞれ４８体積％及び１２体積％となるように混合して用いるようにしたこと以外は実施例６と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 8)
As the heat conductive filler, the wet pulverized boron nitride fine particles obtained in Example 6 and aluminum nitride fine particles (“High heat conductive AlN filler FAN-f05” manufactured by Furukawa Electronics Co., Ltd., average particle diameter: 5 μm) were used. , Heat conduction in the same manner as in Example 6 except that the crushed boron nitride fine particles and aluminum nitride fine particles in the obtained composite material were mixed and used so as to be 48% by volume and 12% by volume, respectively. A sex composite material was obtained. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例６で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 6 (the latter is proportional to the content of boron nitride fine particles).
（比較例６）
熱伝導性フィラーとして前記窒化アルミニウム微粒子（平均粒子径：５μｍ）のみを用い、得られる複合材料中の窒化アルミニウム微粒子の含有率が６０体積％となるようにしたこと以外は実施例８と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Comparative Example 6)
The same as in Example 8 except that only the aluminum nitride fine particles (average particle diameter: 5 μm) were used as the heat conductive filler and the content of the aluminum nitride fine particles in the obtained composite material was 60% by volume. Obtained a thermally conductive composite material. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
（実施例９）
熱伝導性フィラーとして、実施例６において得られた湿式粉砕された窒化ホウ素微粒子と、ダイヤモンド微粒子（ビジョン開発株式会社製「ナノダイヤモンド」、平均粒子径：５μｍ）とを用い、得られる複合材料中の粉砕窒化ホウ素微粒子及びダイヤモンド微粒子の含有率がそれぞれ４８体積％及び１２体積％となるように混合して用いるようにしたこと以外は実施例６と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 9)
As the heat conductive filler, the wet-ground boron nitride fine particles obtained in Example 6 and diamond fine particles (“Nanodiamond” manufactured by Vision Development Co., Ltd., average particle diameter: 5 μm) are used in the obtained composite material. A thermally conductive composite material was obtained in the same manner as in Example 6 except that the crushed boron nitride fine particles and the diamond fine particles were mixed and used so as to be 48% by volume and 12% by volume, respectively. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例６で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 6 (the latter is proportional to the content of boron nitride fine particles).
（比較例７）
熱伝導性フィラーとして前記ダイヤモンド微粒子のみを用い、得られる複合材料中のダイヤモンド微粒子の含有率が６０体積％となるようにしたこと以外は実施例９と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Comparative Example 7)
A thermally conductive composite material was obtained in the same manner as in Example 9 except that only the diamond fine particles were used as the thermally conductive filler and the content of the diamond fine particles in the obtained composite material was 60% by volume. .. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
（実施例１０）
熱伝導性フィラーとして、実施例６において得られた湿式粉砕された窒化ホウ素微粒子と、立方晶窒化ホウ素微粒子（株式会社グローバルダイヤモンド製「立方晶窒化ホウ素（ＣＢＮ）パウダー ＦＢＮ−ＢＭ」、平均粒子径：５μｍ）とを用い、得られる複合材料中の粉砕窒化ホウ素微粒子及び立方晶窒化ホウ素微粒子の含有率がそれぞれ４８体積％及び１２体積％となるように混合して用いるようにしたこと以外は実施例６と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 10)
As the thermally conductive filler, the wet-pulverized boron nitride fine particles obtained in Example 6 and cubic boron nitride fine particles (“Cublic Boron Nitride (CBN) Powder FBN-BM” manufactured by Global Diamond Co., Ltd., average particle diameter). : 5 μm) and mixed so that the contents of the crushed boron nitride fine particles and the cubic boron nitride fine particles in the obtained composite material are 48% by volume and 12% by volume, respectively. A thermally conductive composite material was obtained in the same manner as in Example 6. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例６で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 6 (the latter is proportional to the content of boron nitride fine particles).
（比較例８）
熱伝導性フィラーとして前記立方晶窒化ホウ素微粒子のみを用い、得られる複合材料中の立方晶窒化ホウ素微粒子の含有率が６０体積％となるようにしたこと以外は実施例１０と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Comparative Example 8)
Thermal conductivity is the same as in Example 10 except that only the cubic boron nitride fine particles are used as the heat conductive filler and the content of the cubic boron nitride fine particles in the obtained composite material is 60% by volume. A sex composite material was obtained. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
（実施例１１）
熱伝導性フィラーとして実施例３において得られた湿式粉砕された窒化ホウ素微粒子を用い、得られる複合材料中のフィラー（窒化ホウ素微粒子）含有率が６０体積％となるようにしたこと以外は実施例３と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 11)
Examples except that the wet-ground boron nitride fine particles obtained in Example 3 were used as the thermally conductive filler and the filler (boron nitride fine particles) content in the obtained composite material was set to 60% by volume. A thermally conductive composite material was obtained in the same manner as in 3. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例３で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 3 (the latter is proportional to the content of boron nitride fine particles).
（実施例１２）
熱伝導性フィラーとして、実施例３において得られた湿式粉砕された窒化ホウ素微粒子と、アルミナ微粒子（キンセイマテック株式会社製「セラフ００６１０」、平均粒子径：０．６μｍ）とを用い、得られる複合材料中の粉砕窒化ホウ素微粒子及びアルミナ微粒子の含有率がそれぞれ４８体積％及び１２体積％となるように混合して用いるようにしたこと以外は実施例１１と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Example 12)
A composite obtained by using the wet-ground boron nitride fine particles obtained in Example 3 and alumina fine particles (“Seraph 00160” manufactured by Kinsei Matek Co., Ltd., average particle diameter: 0.6 μm) as the thermally conductive filler. A thermally conductive composite material was obtained in the same manner as in Example 11 except that the crushed boron nitride fine particles and the alumina fine particles in the material were mixed and used so as to be 48% by volume and 12% by volume, respectively. It was. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
また、得られた複合材料における窒化ホウ素微粒子の全量に対する部分劈開窒化ホウ素微粒子の含有率［体積％］及び複合材料の断面面積に対する膨潤窒化ホウ素微粒子に相当する領域の合計面積の比率［％］はいずれも実施例３で得られた複合材料と同等（後者は窒化ホウ素微粒子の含有率に比例）のものであった。 Further, the content ratio [% by volume] of the partially opened boron nitride fine particles to the total amount of the boron nitride fine particles in the obtained composite material and the ratio [%] of the total area of the region corresponding to the swollen boron nitride fine particles to the cross-sectional area of the composite material are All of them were equivalent to the composite material obtained in Example 3 (the latter is proportional to the content of boron nitride fine particles).
（比較例９）
熱伝導性フィラーとして前記アルミナ微粒子（平均粒子径：０．６μｍ）のみを用い、得られる複合材料中のアルミナ微粒子の含有率が６０体積％となるようにしたこと以外は実施例１２と同様にして熱伝導性複合材料を得た。そして、得られた複合材料について実施例５と同様にして熱伝導率測定を行い、圧縮方向に平行な方向（ｚ軸方向）の熱伝導率を求めた。得られた結果を表３に示す。
(Comparative Example 9)
The same as in Example 12 except that only the alumina fine particles (average particle diameter: 0.6 μm) were used as the thermally conductive filler and the content of the alumina fine particles in the obtained composite material was 60% by volume. Obtained a thermally conductive composite material. Then, the obtained composite material was measured for thermal conductivity in the same manner as in Example 5, and the thermal conductivity in the direction parallel to the compression direction (z-axis direction) was determined. The results obtained are shown in Table 3.
＜表３に示した結果の評価＞
表３に示した結果から明らかな通り、熱伝導性フィラーとして部分劈開窒化ホウ素微粒子を含有する湿式粉砕された窒化ホウ素微粒子のみを用いた本発明の熱伝導性複合材料においても高い熱伝導率が達成されているが（実施例６、１１）、熱伝導性フィラーとして熱伝導率が２０Ｗ／ｍＫ以上である高熱伝導性微粒子が更に含有されていると（実施例５、７〜１０、１２）、得られる複合材料の熱伝導率が更に向上することが確認された。
<Evaluation of the results shown in Table 3>
As is clear from the results shown in Table 3, the thermal conductivity composite material of the present invention using only wet-ground boron nitride fine particles containing partially open boron nitride fine particles as the thermal conductive filler also has high thermal conductivity. Although it has been achieved (Examples 6 and 11), when high thermal conductive fine particles having a thermal conductivity of 20 W / mK or more are further contained as the thermally conductive filler (Examples 5, 7 to 10 and 12). It was confirmed that the thermal conductivity of the obtained composite material was further improved.
以上説明したように、本発明によれば、熱伝導性を効率良く向上させることが可能な熱伝導性フィラー及びその製造方法と、優れた熱伝導性を有する熱伝導性複合材料及びその製造方法とを提供することが可能となる。したがって、本発明の複合材料は、熱伝導性に優れているため、例えば、自動車用放熱材料、ヒーター材料等として有用である。 As described above, according to the present invention, a thermally conductive filler capable of efficiently improving thermal conductivity and a method for producing the same, and a thermally conductive composite material having excellent thermal conductivity and a method for producing the same. And can be provided. Therefore, since the composite material of the present invention is excellent in thermal conductivity, it is useful as, for example, a heat radiating material for automobiles, a heater material, and the like.
また、本発明の複合材料として、高い熱伝導性を有していると共に絶縁性のものが得られることから、電気系部品等と組み合わせて使用する場合に絶縁シート等を用いることなく本発明の複合材料のみによって熱を拡散・伝達することが可能となる。したがって、本発明の複合材料は、インバーター、コンバーター等の電力変換器に用いられるパワーデバイスやＣＰＵ等の発熱性電子部品の熱を放熱部材に伝達する中間部材(熱インターフェース材)等としても非常に有用である。 Further, since a composite material of the present invention having high thermal conductivity and insulating properties can be obtained, the present invention can be used without using an insulating sheet or the like when used in combination with an electrical component or the like. Heat can be diffused and transferred only by the composite material. Therefore, the composite material of the present invention is also very useful as an intermediate member (thermal interface material) for transferring the heat of a power device used for a power converter such as an inverter or a converter or a heat-generating electronic component such as a CPU to a heat-dissipating member. It is useful.
１：複合材料、２：熱伝導率測定用試料。 1: Composite material 2: Sample for measuring thermal conductivity.
Claims (7)
前記窒化ホウ素微粒子の少なくとも一部が、窒化ホウ素微粒子が部分的に劈開した部分劈開窒化ホウ素微粒子であり、
前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子が前記複合材料に含有されており、
前記複合材料の断面基準で、前記膨潤窒化ホウ素微粒子に相当する領域の合計面積が、前記複合材料の断面面積に対して１〜５０％である、
ことを特徴とする熱伝導性複合材料。 Hexagonal plate-shaped boron nitride fine particles and at least one selected from the group consisting of cubic boron nitride, diamond, aluminum nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon nitride and silicon carbide have a thermal conductivity of 20 W. A thermally conductive composite material obtained by dispersing highly thermally conductive fine particles of / mK or more as a thermally conductive filler in a matrix.
At least a part of the boron nitride fine particles is partially cleaved boron nitride fine particles in which the boron nitride fine particles are partially cleaved.
The composite material contains swollen boron nitride fine particles in which the matrix is filled and swollen in the cleavage voids of the partially cleaved boron nitride fine particles.
Based on the cross-sectional area of the composite material, the total area of the region corresponding to the swollen boron nitride fine particles is 1 to 50% of the cross-sectional area of the composite material.
A thermally conductive composite material characterized by that.
前記部分劈開窒化ホウ素微粒子を含む六方晶系の板状窒化ホウ素微粒子と、立方晶窒化ホウ素、ダイヤモンド、窒化アルミニウム、酸化アルミニウム、酸化マグネシウム、酸化亜鉛、窒化ケイ素及び炭化ケイ素からなる群から選択される少なくとも一種の熱伝導率が２０Ｗ／ｍＫ以上である高熱伝導性微粒子とを熱伝導性フィラーとしてマトリックス中に分散させて、前記部分劈開窒化ホウ素微粒子の劈開空隙中に前記マトリックスが充填されて膨潤した膨潤窒化ホウ素微粒子を含有する熱伝導性複合材料を得る工程と、
を含むことを特徴とする熱伝導性複合材料の製造方法。 By injecting a fluid containing hexagonal plate-shaped boron nitride particles from a nozzle at high pressure and performing wet collision pulverization, the boron nitride fine particles are partially opened to form a hexagonal plate containing partially opened boron nitride fine particles. The process of obtaining boron nitride fine particles and
It is selected from the group consisting of hexagonal plate-shaped boron nitride fine particles containing the partially opened boron nitride fine particles , and cubic boron nitride, diamond, aluminum nitride, aluminum oxide, magnesium oxide, zinc oxide, silicon nitride and silicon carbide. At least one kind of highly thermally conductive fine particles having a thermal conductivity of 20 W / mK or more was dispersed in the matrix as a thermally conductive filler, and the matrix was filled and swollen in the open voids of the partially opened boron nitride fine particles. The process of obtaining a thermally conductive composite material containing swelled boron nitride fine particles,
A method for producing a thermally conductive composite material, which comprises.
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