JP7138481B2 - Hexagonal boron nitride powder and method for producing the same - Google Patents

Hexagonal boron nitride powder and method for producing the same Download PDF

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JP7138481B2
JP7138481B2 JP2018103131A JP2018103131A JP7138481B2 JP 7138481 B2 JP7138481 B2 JP 7138481B2 JP 2018103131 A JP2018103131 A JP 2018103131A JP 2018103131 A JP2018103131 A JP 2018103131A JP 7138481 B2 JP7138481 B2 JP 7138481B2
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boron nitride
nitride powder
hexagonal boron
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JP2019206455A (en
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祐一 池田
健太郎 福田
祥太 台木
恭一 藤波
雄一郎 三鍋
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Tokuyama Corp
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Description

本発明は、新規な六方晶窒化ホウ素粉末及びその製造方法に関する。詳しくは、樹脂との親和性に優れ、得られる樹脂組成物において高い熱中性子吸収性能、高い熱伝導率、優れた絶縁耐力、及び銅箔等との高い接着強度を付与することが可能な、六方晶窒化ホウ素粉末及びその製造方法を提供するものである。 The present invention relates to a novel hexagonal boron nitride powder and a method for producing the same. Specifically, it has excellent affinity with resins, and can impart high thermal neutron absorption performance, high thermal conductivity, excellent dielectric strength, and high adhesive strength to copper foil etc. in the resulting resin composition. Kind Code: A1 A hexagonal boron nitride powder and a method for producing the same are provided.

ＳＲＡＭ（Ｓｔａｔｉｃ Ｒａｍｄｏｍ Ａｃｃｅｓｓ Ｍｅｍｏｒｙ）やＤＲＡＭ（Ｄｙｎａｍｉｃ Ｒａｎｄｏｍ Ａｃｃｅｓｓ Ｍｅｍｏｒｙ）といった半導体メモリで保持データが自然に破壊されることがあり、この現象はソフトエラーと呼ばれている。近年、半導体素子の微細化、動作電圧の低電圧化によりソフトエラーの問題がより重要となってきている。ソフトエラーの起因となる放射線は３つある。半導体パッケージ材に含まれる微量な放射性物質に起因するα線、宇宙線に起因する高速中性子、熱中性子である。このうち熱中性子起因のソフトエラーは半導体中に含まれる１０Ｂと熱中性子が反応することで発生する。熱中性子起因のソフトエラーの抑制には半導体中の１０Ｂの排除、または熱中性子が半導体に入る前に中性子捕獲断面積の大きい元素で吸収することが有効である。中性子捕獲断面積が大きい元素には３Ｈｅ、６Ｌｉ、１０Ｂ等がある。 In semiconductor memories such as SRAMs (Static Random Access Memories) and DRAMs (Dynamic Random Access Memories), stored data may be destroyed spontaneously, and this phenomenon is called a soft error. In recent years, the problem of soft errors has become more important due to the miniaturization of semiconductor devices and the reduction in operating voltage. There are three types of radiation that cause soft errors. They are alpha rays originating from trace amounts of radioactive substances contained in semiconductor package materials, fast neutrons originating from cosmic rays, and thermal neutrons. Of these, soft errors caused by thermal neutrons are generated by reaction between 10 B contained in the semiconductor and thermal neutrons. To suppress soft errors caused by thermal neutrons, it is effective to eliminate 10 B in the semiconductor, or to absorb thermal neutrons in an element with a large neutron capture cross section before entering the semiconductor. Elements with large neutron capture cross sections include 3 He, 6 Li, 10 B, and the like.

熱中性子起因のソフトエラー対策として、特許文献１にあるような窒化ホウ素を含有するシートが考案されており、該窒化ホウ素含有シートは、熱伝導性や電気絶縁性に優れているため、該窒化ホウ素含有シートを使用することにより、半導体装置の放熱特性および電気絶縁性を改善することができるとされている。しかしながら、特許文献１のようにソフトエラー率を一桁下げることを目標とした場合、上記シートについて、窒化ホウ素の含有量を６５％と高充填しても１ｍｍ程度の厚みが必要とされる。このような窒化ホウ素含有シートを一般的な方法で製作した場合に得られる熱伝導性能は、熱伝導性絶縁シートとしては低く好適ではないことを本発明者等は確認した。 As a countermeasure against soft errors caused by thermal neutrons, a sheet containing boron nitride as described in Patent Document 1 has been devised. Since the boron nitride-containing sheet has excellent thermal conductivity and electrical insulation, the nitriding The use of a boron-containing sheet is said to improve the heat dissipation properties and electrical insulation properties of semiconductor devices. However, when the goal is to reduce the soft error rate by one digit as in Patent Document 1, the sheet needs to have a thickness of about 1 mm even if the boron nitride content is as high as 65%. The present inventors have confirmed that the thermal conductivity obtained when such a boron nitride-containing sheet is produced by a general method is low and not suitable as a thermally conductive insulating sheet.

ところで、天然に存在するホウ素は２種類の安定同位体１０Ｂと１１Ｂから成っており、その存在比は１０Ｂが１９．９％、１１Ｂが８０．１％である。濃縮等の操作を行った場合を除き、天然由来のホウ素を原料としたホウ素化合物は、その天然のホウ素の安定同位体存在比を引き継ぐため、天然由来のホウ素原料から製造した窒化ホウ素を含有するシートについて、熱中性子の吸収に有効に作用しているホウ素は全ホウ素中のおよそ２０％であり、熱中性子吸収性能の点において改善の余地があった。この熱中性子吸収性能を向上させるには、例えば、シートの厚みや含有量を増大することが有効であるが、その効率は悪い。また、シートの厚みが増すと、前記したように、熱抵抗を増大させるため熱伝導性能を損なう虞がある。 By the way, naturally occurring boron consists of two kinds of stable isotopes, 10 B and 11 B, and the abundance ratio of 10 B is 19.9% and 11 B is 80.1%. Boron compounds made from naturally-occurring boron as a raw material contain boron nitride produced from naturally-occurring boron raw materials in order to inherit the stable isotope abundance ratio of the naturally-occurring boron, except when operations such as concentration are performed. About 20% of the total boron in the sheet is effective in absorbing thermal neutrons, and there is room for improvement in terms of thermal neutron absorption performance. To improve the thermal neutron absorption performance, for example, it is effective to increase the thickness and content of the sheet, but the efficiency is poor. Further, when the thickness of the sheet is increased, the heat resistance is increased as described above, which may impair the heat conduction performance.

前記熱伝導性絶縁シートに充填し使用する六方晶窒化ホウ素粒子は、一般に、結晶構造に由来する厚みの薄い鱗片状粒子よりなる一次粒子を含む。そのため、上記窒化ホウ素粒子は、該熱伝導性絶縁シート中において、その厚み方向に配向し易い。しかも、一般に、窒化ホウ素粒子は結晶構造に由来して、面方向に比べて厚さ方向には低い熱伝導性しか示さないという熱的異方性を有する。それゆえ、上記熱伝導性絶縁シートの厚さ方向の熱伝導率は低い。 The hexagonal boron nitride particles used to fill the thermally conductive insulating sheet generally contain primary particles made of thin scaly particles derived from the crystal structure. Therefore, the boron nitride particles are easily oriented in the thickness direction of the thermally conductive insulating sheet. Moreover, in general, boron nitride particles have thermal anisotropy due to their crystal structure, in which they show lower thermal conductivity in the thickness direction than in the plane direction. Therefore, the thermal conductivity in the thickness direction of the thermally conductive insulating sheet is low.

また、六方晶窒化ホウ素粒子はＢ原子とＮ原子が交互に結合した六方晶系平面が積層しており、上記平面上には官能基が存在せず、平面に直交した端面のＢ原子にＯＨ基、ＮＨ２基が結合しているが、一般的に六方晶窒化ホウ素粒子は鱗片状であり、上記平面に対して端面の面積が少ないため、官能基量も少ない。 In addition, the hexagonal boron nitride particles have stacked hexagonal planes in which B atoms and N atoms are alternately bonded, and no functional groups are present on the planes, and OH In general, hexagonal boron nitride particles are scaly, and the end face area is small with respect to the plane, so the amount of functional groups is also small.

上記官能基量が少ない六方晶窒化ホウ素粉末は、官能基量が少ないが故に、樹脂との親和性が悪く、樹脂組成物とした際に、六方晶窒化ホウ素と樹脂界面に熱抵抗が生じ、熱が伝わり難い傾向がある。このように、六方晶窒化ホウ素粉末を樹脂充填用無機フィラーとして使用する際には、鱗片状由来の粒子形状及び表面官能基が乏しいことが障壁となり、上記問題が発生することとなる。 The hexagonal boron nitride powder having a small amount of functional groups has poor affinity with resins because of the small amount of functional groups, and when it is made into a resin composition, thermal resistance occurs at the interface between hexagonal boron nitride and the resin. Heat tends to be difficult to transfer. Thus, when hexagonal boron nitride powder is used as an inorganic filler for resin filling, the poor particle shape and surface functional groups derived from the scaly form are obstacles, and the above problems occur.

また、官能基量の多い六方晶窒化ホウ素粉末として、先行文献２および３記載の通り、不活性雰囲気下で大気圧プラズマ処理を施し、ＮＨ２基を直接導入した六方晶窒化ホウ素粉末や、ホウ酸、ホウ砂、メラミンを原料としたメラミン法によって合成された、ＯＨ基、ＮＨ２基を含有した六方晶窒化ホウ素粉末が提供されている。 In addition, as hexagonal boron nitride powder with a large amount of functional groups, as described in Prior Documents 2 and 3, hexagonal boron nitride powder obtained by performing atmospheric pressure plasma treatment under an inert atmosphere and directly introducing NH groups, and boron There is provided a hexagonal boron nitride powder containing OH groups and NH2 groups synthesized by a melamine method using acid, borax and melamine as raw materials.

また、非特許文献１には、永久気体流ＢＣｌ３とＮＨ３とから化学気相反応により製造された窒化ホウ素に、室温で１時間２０ｍｂａｒのＨ２を付加すると、３１００－４０００ｃｍ－１の範囲にＯＨ、ＮＨ／ＮＨ２バンドの非対称拡張が見られることが報告されているが、この範囲における最高吸収ピークは３１００－３５００ｃｍ－１の範囲に存在する点で特徴的である。 Also, in Non-Patent Document 1, the addition of 20 mbar of H 2 for 1 h at room temperature to boron nitride produced by chemical vapor reaction from permanent gas streams BCl 3 and NH 3 results in a range of 3100-4000 cm −1 . have been reported to exhibit asymmetric broadening of the OH, NH/NH2 bands in , and the highest absorption peak in this range is characteristic in that it exists in the range of 3100-3500 cm -1 .

しかしながら、一般的な窒化ホウ素粉末の表面改質処理である、紫外線照射、オゾン処理、プラズマ処理等による官能基導入処理は、工業的な大量生産の難しさやコストアップだけでなく、窒化ホウ素表面を活性化させてしまうため、空気中の水分等との反応性も上昇し、窒化ホウ素粉末の耐水性等を低下させてしまい、得られる樹脂組成物の絶縁耐力を低下させてしまう虞がある。また、ＯＨ基を含有した窒化ホウ素粉末も同様に、耐水性等の問題が発生する虞がある。 However, the introduction of functional groups by ultraviolet irradiation, ozone treatment, plasma treatment, etc., which are general surface modification treatments of boron nitride powder, not only make industrial mass production difficult and costly, but also reduce the boron nitride surface. Since it is activated, the reactivity with moisture in the air is increased, the water resistance of the boron nitride powder is lowered, and the dielectric strength of the obtained resin composition may be lowered. Similarly, boron nitride powder containing OH groups may also have problems such as water resistance.

特開平１１－３５４６９０号公報JP-A-11-354690 特開２０１５－１３７３３５号公報JP 2015-137335 A 特開２０１０－０７６９５６号公報JP 2010-076956 A

Ｌａｎｇｍｕｉｒ １９９３ ９ １４８６－１４９１Langmuir 1993 9 1486-1491

従って、本発明の目的は、樹脂との高い親和性と高い耐水性を発現し、さらに、樹脂に充填した際に高い熱中性子吸収性能、熱伝導性や絶縁耐力の高い樹脂組成物を与える六方晶窒化ホウ素粉末を提供することにある。 Therefore, the object of the present invention is to provide a hexagonal resin composition that exhibits high affinity with resins and high water resistance, and also has high thermal neutron absorption performance, high thermal conductivity and high dielectric strength when filled in resins. An object of the present invention is to provide a crystalline boron nitride powder.

本発明の他の目的は、本発明の上記六方晶窒化ホウ素粉末を製造する方法を提供することにある。 Another object of the present invention is to provide a method for producing the hexagonal boron nitride powder of the present invention.

本発明の更に他の目的および利点は、以下の説明から明らかになろう。 Further objects and advantages of the present invention will become apparent from the following description.

本発明者等は、上記課題を解決するため鋭意検討を行った。その結果、全ホウ素中の１０Ｂの濃縮度が５０％以上である１０Ｂ濃縮含酸素ホウ素化合物、カーボン源及び含酸素カルシウム化合物を用いて行う還元窒化反応において、特定の製造方法を採用することによって、六方晶窒化ホウ素粒子の表面官能基に由来するピークが確認される、拡散反射赤外分光スペクトルによる３１００～３８００ｃｍ－１の測定範囲において、３５３０～３５９０ｃｍ－１の範囲に最高吸収ピークを有する六方晶窒化ホウ素粉末を得ることに成功し、かかる六方晶窒化ホウ素粉末は、樹脂との親和性に優れ、得られる樹脂組成物において高い熱中性子吸収性能および熱伝導率を付与することができ、上記目的を達成し得ることを見出し、本発明を完成するに至った。 The inventors of the present invention have made intensive studies to solve the above problems. As a result, in the reductive nitriding reaction using a 10 B-enriched oxygenated boron compound having a 10 B enrichment in total boron of 50% or more, a carbon source, and an oxygenated calcium compound, a specific production method should be adopted. A peak derived from the surface functional groups of the hexagonal boron nitride particles is confirmed by the diffuse reflectance infrared spectroscopy spectrum of 3100 to 3800 cm -1 , and has the highest absorption peak in the range of 3530 to 3590 cm -1 Succeeded in obtaining hexagonal boron nitride powder, such hexagonal boron nitride powder has excellent affinity with resin, and can impart high thermal neutron absorption performance and thermal conductivity to the resulting resin composition, The inventors have found that the above object can be achieved, and have completed the present invention.

即ち、本発明によれば、全ホウ素中の１０Ｂの存在比が５０％以上であり、拡散反射赤外分光スペクトルの３１００～３８００ｃｍ－１の測定範囲における最高吸収ピークが３５３０～３５９０ｃｍ－１の範囲にある六方晶窒化ホウ素粉末が提供される。 That is, according to the present invention, the abundance ratio of 10 B in the total boron is 50% or more, and the highest absorption peak in the measurement range of 3100 to 3800 cm -1 of the diffuse reflectance infrared spectrum is 3530 to 3590 cm -1 . A range of hexagonal boron nitride powders is provided.

また、上記六方晶窒化ホウ素粉末は、拡散反射赤外分光スペクトルの８００ｃｍ－１付近の六方晶窒化ホウ素に由来する吸収ピーク高さＡと、３５３０～３５９０ｃｍ－１の範囲における最高吸収ピーク高さＢの比（Ｂ／Ａ）が０．０２以上であることが好ましい。 In addition, the hexagonal boron nitride powder has an absorption peak height A derived from hexagonal boron nitride near 800 cm -1 of the diffuse reflectance infrared spectrum, and a maximum absorption peak height B in the range of 3530 to 3590 cm -1 . ratio (B/A) is preferably 0.02 or more.

また、上記六方晶窒化ホウ素粉末は、比表面積が１５ｍ２／ｇ以下であることが好ましく、酸素濃度が０．３質量％以下であることが好ましい。 The hexagonal boron nitride powder preferably has a specific surface area of 15 m 2 /g or less and an oxygen concentration of 0.3 mass % or less.

更に、上記六方晶窒化ホウ素純度が９９．３％以上であることが好ましい。 Furthermore, the hexagonal boron nitride purity is preferably 99.3% or more.

更にまた、本発明は、前記窒化ホウ素粉末は、その特性より、中性子吸収用組成物として好適であり、該中性子吸収用組成物と、窒化アルミニウム、酸化アルミニウムいずれか一つを含むフィラー混合物を充填した樹脂組成物、該樹脂組成物よりなる放熱絶縁シート、該放熱絶縁シートよりなる電子部品の放熱絶縁部材として好適に使用される。 Furthermore, in the present invention, the boron nitride powder is suitable as a neutron absorbing composition due to its properties, and a filler mixture containing the neutron absorbing composition and either one of aluminum nitride and aluminum oxide is filled. It is suitably used as a resin composition, a heat-dissipating insulating sheet made of the resin composition, and a heat-dissipating insulating member of an electronic component made of the heat-dissipating insulating sheet.

本発明の六方晶窒化ホウ素粉末は、全ホウ素中の１０Ｂの濃縮度が５０％以上である１０Ｂ濃縮含酸素ホウ素化合物、カーボン源、含酸素カルシウム化合物を、含酸素ホウ素化合物に含まれるＢ源とカーボン源に含まれるＣ源の割合であるＢ／Ｃ（元素比）換算で０．７５～０．８５、１０Ｂ濃縮含酸素ホウ素化合物とカーボン源との合計量（Ｂ２Ｏ３、Ｃ換算値）１００質量部に対して含酸素カルシウム化合物をＣａＯ換算で１０～１５質量部となる割合で混合し、該混合物を窒素雰囲気下にて１４５０～１５５０℃で４時間以上、１６５０～２１００℃で２時間以上加熱して、還元窒化した後、反応生成物中に存在する窒化ホウ素以外の副生成物を酸洗浄により除去することを特徴とする六方晶窒化ホウ素粉末の製造方法において、該カーボン源の硫黄濃度を１０００～１００００ｐｐｍの範囲に調整することにより、好適に製造することができる。なお、「１０Ｂ濃縮」とは、１０Ｂの存在比を高めた材料を指す。 The hexagonal boron nitride powder of the present invention contains a 10 B-enriched oxygenated boron compound having a concentration of 10 B in the total boron of 50% or more, a carbon source, an oxygenated calcium compound, and B contained in the oxygenated boron compound 0.75 to 0.85 in terms of B/C (element ratio), which is the ratio of the C source contained in the source and the carbon source, the total amount of the 10 B-enriched oxygen-containing boron compound and the carbon source (B 2 O 3 , C conversion value) 100 parts by mass of the oxygen-containing calcium compound is mixed in a ratio of 10 to 15 parts by mass in terms of CaO, and the mixture is heated at 1450 to 1550 ° C. for 4 hours or more under a nitrogen atmosphere. A method for producing a hexagonal boron nitride powder, characterized in that after reducing and nitriding by heating at ° C. for 2 hours or more, by-products other than boron nitride present in the reaction product are removed by acid washing, By adjusting the sulfur concentration of the carbon source to the range of 1000 to 10000 ppm, it can be produced suitably. In addition, " 10 B-enriched" refers to a material in which the abundance ratio of 10 B is increased.

上記方法によれば、本発明の六方晶窒化ホウ素粉末を、還元窒化法により直接製造することができる。 According to the above method, the hexagonal boron nitride powder of the present invention can be directly produced by the reductive nitriding method.

本発明の六方晶窒化ホウ素粉末は、前記したように、全ホウ素中の１０Ｂの存在比が５０％以上であり、拡散反射赤外分光スペクトルの３１００～３８００ｃｍ－１の測定範囲における最高吸収ピークが３５３０～３５９０ｃｍ－１の範囲にあることを最大の特徴とする。 As described above, the hexagonal boron nitride powder of the present invention has an abundance ratio of 10 B in the total boron of 50% or more, and the highest absorption peak in the measurement range of 3100 to 3800 cm -1 of the diffuse reflectance infrared spectrum. is in the range of 3530 to 3590 cm -1 .

一般的に、天然のホウ素には、１０Ｂと１１Ｂとが同位体として１０Ｂが１９．９％、１１Ｂが８０．１％の割合で存在する。六方晶窒化ホウ素粉末は、原料のホウ素化合物中のホウ素の同位体存在比が引き継がれるため、天然のホウ素由来のホウ素化合物を原料として使用し製造された従来の六方晶窒化ホウ素粉末は、熱中性子の吸収に有効に作用する１０Ｂの存在比は、およそ２０％と本発明の六方晶窒化ホウ素粉末の５０％以上と比べて少ない。 In general, natural boron contains 10 B and 11 B as isotopes at a ratio of 19.9% for 10 B and 80.1% for 11 B. Since the hexagonal boron nitride powder inherits the boron isotope abundance ratio in the raw material boron compound, conventional hexagonal boron nitride powder produced using a boron compound derived from natural boron as a raw material has a thermal neutron The abundance ratio of 10 B that effectively acts on the absorption of is about 20%, which is less than 50% or more of the hexagonal boron nitride powder of the present invention.

また、一般的な六方晶窒化ホウ素粉末表面のＮＨ２基を拡散反射赤外分光法で測定した場合、拡散反射赤外分光スペクトルの３１００～３８００ｃｍ－１の測定範囲において、３３５０～３５００ｃｍ－１の範囲のＮＨ２基対称収縮振動ピークもしくは、３６００～３７５０ｃｍ－１の範囲のＯＨ基が最高吸収ピークであり、３５３０～３５９０ｃｍ－１の範囲のＮＨ２基非対称収縮振動ピークが最高吸収ピークとして観測された例は存在しない。 In addition, when the NH 2 group on the surface of a general hexagonal boron nitride powder is measured by diffuse reflectance infrared spectroscopy, in the measurement range of 3100 to 3800 cm -1 of the diffuse reflectance infrared spectrum, 3350 to 3500 cm -1 The NH2 group symmetric contraction vibration peak in the range or the OH group in the range of 3600 to 3750 cm -1 is the highest absorption peak, and the NH2 group asymmetric contraction vibration peak in the range of 3530 to 3590 cm -1 is observed as the highest absorption peak. No example exists.

従って、本発明の六方晶窒化ホウ素粉末は、かかる特徴により、樹脂との親和性に優れるとともに、得られる樹脂組成物において高い熱中性子吸収性能と高い熱伝導率を示す。 Therefore, the hexagonal boron nitride powder of the present invention has excellent affinity with resins, and exhibits high thermal neutron absorption performance and high thermal conductivity in the resulting resin composition.

前記３５３０～３５９０ｃｍ－１の範囲のＮＨ２基非対称収縮振動ピークが最高吸収ピークで観測される本発明の六方晶窒化ホウ素粉末がかかる特性を発現する理由は明らかではないが、六方晶窒化ホウ素粉末のＴＥＭ（Ｔｒａｎｓｍｉｓｓｉｏｎ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ）観察によれば、本発明の六方晶窒化ホウ素粉末を構成する六方晶窒化ホウ素の粒子端部は、比較例１のような従来の六方晶窒化ホウ素の粒子端部がループ状に閉塞しているのに対して、粒子端部が変性し、ループが切れたように見える状態となっており、この構造においてＮＨ２基の密度が高い状態で上記粒子端部に存在することにより、前記特徴的ピークを示し、そして、樹脂との親和性が発現されるものと推定している。また、従来の後処理により官能基を付与する処理をしたものに対して、粒子端部以外の箇所においては、加水分解を引き起こす原因となるＯＨ基は殆ど存在せず、これにより、高い耐水性を発現する。 Although it is not clear why the hexagonal boron nitride powder of the present invention, in which the NH 2 group asymmetric contraction vibration peak in the range of 3530 to 3590 cm −1 is observed as the highest absorption peak, exhibits such characteristics, the hexagonal boron nitride powder According to TEM (Transmission Electron Microscope) observation, the particle edges of the hexagonal boron nitride constituting the hexagonal boron nitride powder of the present invention are different from those of conventional hexagonal boron nitride particles such as those in Comparative Example 1. While it is closed in a loop shape, the end of the particle is denatured and the loop appears to be broken. It is presumed that by doing so, the characteristic peak is shown and the affinity with the resin is expressed. In addition, in contrast to the conventional post-treatment for imparting functional groups, there are almost no OH groups that cause hydrolysis at locations other than the end of the particles, and as a result, high water resistance is achieved. express.

また、前記本発明の六方晶窒化ホウ粉末の製造方法によれば、１０Ｂ濃縮含酸素ホウ素化合物、特定の硫黄濃度を有するカーボン源、含酸素カルシウム化合物を使用することにより、本発明の六方晶窒化ホウ素粉末を、特定の加熱条件で還元窒化法により直接製造することができる。 Further, according to the method for producing the hexagonal boron nitride powder of the present invention, the hexagonal boron nitride powder of the present invention is obtained by using the 10 B-enriched oxygenated boron compound, the carbon source having a specific sulfur concentration, and the oxygenated calcium compound. Boron nitride powder can be directly produced by a reductive nitriding method under certain heating conditions.

拡散反射赤外分光測定の８００ｃｍ－１付近の吸収ピーク高さＡと３５３０～３５９０ｃｍ－１の吸収ピーク高さＢの比Ｂ／Ａの求め方を図解した図である。FIG. 2 is a diagram illustrating how to determine a ratio B/A between an absorption peak height A near 800 cm −1 and an absorption peak height B between 3530 and 3590 cm −1 in diffuse reflectance infrared spectroscopy. １０Ｂの存在比と熱中性子吸収性能の関係を示した図である。FIG. 3 is a diagram showing the relationship between the abundance ratio of 10 B and the thermal neutron absorption performance.

（六方晶窒化ホウ粉末）
本発明において、後述する実施例、比較例において作製した粉末を、Ｘ線回折測定において、六方晶窒化ホウ素以外の帰属ピーク無き事を確認し、六方晶窒化ホウ素粉末として同定した後に、更なる分析を行った。Ｘ線回折測定は、Ｒｉｇａｋｕ社製全自動水平型多目的Ｘ線回折装置 ＳｍａｒｔＬＢ／Ａを用いて測定した。測定条件はスキャンスピード２０度／分、ステップ幅０．０２度、スキャン範囲１０～９０度とした。 (Hexagonal boron nitride powder)
In the present invention, the powders produced in Examples and Comparative Examples to be described later were confirmed to have no attributed peaks other than hexagonal boron nitride in X-ray diffraction measurement, and after being identified as hexagonal boron nitride powder, further analysis was performed. did The X-ray diffraction measurement was performed using a fully automatic horizontal multi-purpose X-ray diffractometer SmartLB/A manufactured by Rigaku. The measurement conditions were a scan speed of 20 degrees/minute, a step width of 0.02 degrees, and a scan range of 10 to 90 degrees.

本発明において、六方晶窒化ホウ素粉末の全ホウ素中の１０Ｂの存在比は、後述する実施例に示すように、二次イオン質量分析法によって確認することができる。例えば、アルバック・ファイ株式会社製：ＰＨＩ ＡＤＥＰＴ－１０１０を用いて測定することが可能である。 In the present invention, the abundance ratio of 10 B in the total boron in the hexagonal boron nitride powder can be confirmed by secondary ion mass spectrometry, as shown in the examples below. For example, PHI ADEPT-1010 manufactured by ULVAC-PHI, Inc. can be used for measurement.

そして、本発明の六方晶窒化ホウ素粉末の１０Ｂの存在比は、５０％以上であることを特徴とする。また、得られる熱中性子吸収性能の観点から、１０Ｂの存在比は高いほど良いので、９０％以上がより好ましく、９５％以上が更に好ましく、９９％以上がより更に好ましい。即ち、１０Ｂの存在比を高めることで、より高い熱中性子吸収性能が得られる。 The abundance ratio of 10 B in the hexagonal boron nitride powder of the present invention is characterized by 50% or more. Moreover, from the viewpoint of the obtained thermal neutron absorption performance, the higher the abundance ratio of 10 B, the better. That is, by increasing the abundance ratio of 10 B, higher thermal neutron absorption performance can be obtained.

また、本発明において、六方晶窒化ホウ素粉末の拡散反射赤外分光スペクトルは、後述する実施例に示すように、拡散反射赤外分光法によって確認することができる。例えば、アジレント・テクノロジー株式会社製：ＦＴＳ－３０００を用いて測定することが可能である。 In addition, in the present invention, the diffuse reflectance infrared spectroscopy spectrum of the hexagonal boron nitride powder can be confirmed by diffuse reflectance infrared spectroscopy as shown in the examples described later. For example, it can be measured using FTS-3000 manufactured by Agilent Technologies.

そして、本発明の六方晶窒化ホウ素粉末は、拡散反射赤外分光スペクトルの３１００～３８００ｃｍ－１の測定範囲における最高吸収ピークが３５３０～３５９０ｃｍ－１の範囲、特に、３５６８ｃｍ－１付近にあることを特徴とする。 And the hexagonal boron nitride powder of the present invention has the highest absorption peak in the range of 3100 to 3800 cm -1 of the diffuse reflectance infrared spectroscopy spectrum in the range of 3530 to 3590 cm -1 , especially in the vicinity of 3568 cm -1 . Characterized by

一般に、六方晶窒化ホウ素粉末の表面官能基を同定する手段として、拡散反射赤外分光測定による方法があり、３６００～３７５０ｃｍ－１の範囲においてＯＨ基、３３５０～３５００ｃｍ－１の範囲にＮＨ２基の対称収縮振動、３５３０～３５９０ｃｍ－１の範囲にＮＨ２基の非対称収縮振動が観測されることが公知である。 In general, as a means of identifying the surface functional groups of hexagonal boron nitride powder, there is a method by diffuse reflectance infrared spectroscopy. It is known that symmetric contraction vibrations of NH 2 groups are observed in the range of 3530-3590 cm −1 .

しかしながら、従来発明の六方晶窒化ホウ素粉末において、３１００～３８００ｃｍ－１の粒子表面の官能基ピーク範囲において、３５３０～３５９０ｃｍ－１の範囲のＮＨ２基の非対称収縮振動ピークが最高吸収ピークの六方晶窒化ホウ素粉末を得られた例はない。 However, in the hexagonal boron nitride powder of the conventional invention, in the functional group peak range of the particle surface of 3100 to 3800 cm -1 , the asymmetric contraction vibration peak of the NH 2 group in the range of 3530 to 3590 cm -1 is the highest absorption peak hexagonal There are no examples of obtaining boron nitride powder.

本発明の六方晶窒化ホウ素粉末は、上記ＮＨ２基の非対称収縮振動ピークが最高吸収ピークであることが特徴であり、他の六方晶窒化ホウ素粉末とは異なる特徴を有している。 The hexagonal boron nitride powder of the present invention is characterized in that the asymmetric contraction vibration peak of the NH 2 group is the highest absorption peak, and has characteristics different from other hexagonal boron nitride powders.

対称と非対称収縮振動のピーク強度の違いは、例えば芳香族ＮＯ２基の場合、パラ位にＮＨ２基が置換されるとＮＯ２基対称伸縮振動の強度が増大することが知られている。これは、ＮＯ２基と直接結合する原子の環境の違いによって生じるものであると推定されている。そして、本発明の六方晶窒化ホウ素粉末が、３５３０～３５９０ｃｍ－１のＮＨ２基非対称収縮振動に最高吸収ピークが観測されるということは、ＮＨ２基の密度が高いことを意味し、ＴＥＭで観察された本発明の六方晶窒化ホウ素粒子の端部が切れた部分にＮＨ２基が集中して存在していることが予想される。 The difference between the peak intensities of symmetric and asymmetric stretching vibrations is that, for example, in the case of aromatic NO2 groups, it is known that the intensity of NO2 group symmetric stretching vibrations increases when NH2 groups are substituted at the para - positions. It is presumed that this arises from differences in the environment of the atoms that directly bond with the NO2 groups. And the fact that the hexagonal boron nitride powder of the present invention has the highest absorption peak in the NH2 group asymmetric contraction vibration at 3530-3590 cm −1 means that the density of the NH2 group is high, and the TEM It is expected that the NH 2 groups are concentrated in the portions where the ends of the hexagonal boron nitride particles of the present invention are observed.

そして、上記のように密度が高い状態でＮＨ２基が存在することにより、樹脂との親和性が発現され、樹脂組成物とした際の熱抵抗となる、粒子、樹脂界面の熱抵抗を低減させることが可能となる。また、従来の後処理により官能基を付与する処理をしたものに対して、粒子端部以外の箇所においては、加水分解を引き起こす原因となるＯＨ基は殆ど存在せず、これにより、高い耐水性を発現する。 Then, the presence of NH2 groups in a state of high density as described above expresses affinity with the resin, and reduces the thermal resistance at the interface between the particles and the resin, which becomes the thermal resistance when the resin composition is formed. It is possible to In addition, in contrast to the conventional post-treatment for imparting functional groups, there are almost no OH groups that cause hydrolysis at locations other than the end of the particles, and as a result, high water resistance is achieved. express.

本発明において、上記樹脂との親和性及び耐水性を特に向上させるためには、本発明の六方晶窒化ホウ素粉末の、上記３５３０～３５９０ｃｍ－１の範囲のＮＨ２基非対称収縮振動ピーク強度について、拡散反射赤外分光測定の８００ｃｍ－１付近の吸収ピーク高さＡと３５３０～３５９０ｃｍ－１の吸収ピーク高さＢとの比Ｂ／Ａが０．０２以上であることが好ましい。より好ましくは０．０３以上、更に好ましくは０．０４以上である。また、上限は特に制限されないが、０．１５、特に、０．１０程度である。 In the present invention, in order to particularly improve the affinity with the resin and the water resistance, the NH 2 group asymmetric contraction vibration peak intensity in the range of 3530 to 3590 cm -1 of the hexagonal boron nitride powder of the present invention is The ratio B/A between the absorption peak height A near 800 cm −1 and the absorption peak height B between 3530 and 3590 cm −1 in diffuse reflectance infrared spectroscopy is preferably 0.02 or more. It is more preferably 0.03 or more, still more preferably 0.04 or more. Although the upper limit is not particularly limited, it is about 0.15, particularly about 0.10.

本発明において、上記ピーク高さＢ／Ａは、図１に示す六方晶窒化ホウ素粉末の拡散反射赤外分光スペクトルデータにおいて、吸収ピークにベースラインを引き、ピークトップから引いた垂線とベースラインとの交点までの距離を測定することにより求めたものである。 In the present invention, the peak height B / A is, in the diffuse reflectance infrared spectroscopy spectrum data of the hexagonal boron nitride powder shown in FIG. It is obtained by measuring the distance to the intersection of

本発明の六方晶窒化ホウ素粉末は、酸素濃度が０．３質量％以下、特に、０．２、更には０．１質量％以下であることが好ましい。酸素濃度をかかる範囲とすることによって、六方晶窒化ホウ素粉末の耐水性を特に向上することができる。 The hexagonal boron nitride powder of the present invention preferably has an oxygen concentration of 0.3% by mass or less, particularly 0.2% by mass or less, and more preferably 0.1% by mass or less. By setting the oxygen concentration within this range, the water resistance of the hexagonal boron nitride powder can be particularly improved.

上記六方晶窒化ホウ素粉末の酸素濃度は、後述する実施例に示すように非分散赤外吸収法によって測定し、例えば、ＨＯＲＩＢＡ社製ＥＭＧＡ－６２０Ｗ（商品名）によって確認することができる。 The oxygen concentration of the hexagonal boron nitride powder is measured by a non-dispersive infrared absorption method as shown in Examples described later, and can be confirmed by, for example, EMGA-620W (trade name) manufactured by HORIBA.

本発明の六方晶窒化ホウ素粉末の比表面積は、１５．０ｍ２／ｇ以下、特に、０．５～１２．０ｍ２／ｇ、更には、０．７～８．０ｍ２／ｇであるものが好ましい。即ち、１５．０ｍ２／ｇを超える六方晶窒化ホウ素粉末は、微粒子を多く含むため、絶縁放熱シート内での熱抵抗の原因になるだけでなく、粉が舞いやすくなる等といったハンドリング性が低下することが懸念される。 The hexagonal boron nitride powder of the present invention has a specific surface area of 15.0 m 2 /g or less, particularly 0.5 to 12.0 m 2 /g, further 0.7 to 8.0 m 2 /g. is preferred. That is, since the hexagonal boron nitride powder having a density exceeding 15.0 m 2 /g contains many fine particles, it not only causes heat resistance in the insulating heat-dissipating sheet, but also causes deterioration in handling properties such as easy dusting. It is feared that

上記六方晶窒化ホウ素粉末の比表面積は、後述する実施例に示すように、ＢＥＴ１点法によって測定し、例えばマウンテック社製：Ｍａｃｓｏｒｂ ＨＭ ｍｏｄｅｌ－１２０１（商品名）によって確認することができる。 The specific surface area of the hexagonal boron nitride powder can be measured by the BET single-point method, as shown in Examples described later, and can be confirmed by, for example, Macsorb HM model-1201 (trade name) manufactured by Mountec.

また、本発明において、六方晶窒化ホウ素粉末の粒度分布は、特に指定するものではないが、一般的に平均粒径が０．１～１５０μｍ程度が好ましい。 In the present invention, the particle size distribution of the hexagonal boron nitride powder is not particularly specified, but generally the average particle size is preferably about 0.1 to 150 μm.

粒度分布は、湿式レーザー回折粒度分布法によって測定することが可能である。例えばＨＯＲＩＢＡ社製：ＬＡ－９５０Ｖ２（商品名）によって確認することができる。 Particle size distribution can be measured by a wet laser diffraction particle size distribution method. For example, it can be confirmed by LA-950V2 (trade name) manufactured by HORIBA.

本発明の六方晶窒化ホウ素粉末の純度は、９９．３質量％以上、特に、９９．６質量％、更には９９．９質量％以上であることが好ましい。即ち、六方晶窒化ホウ素粉末の純度が９９．３質量％より低下すると、不純物による樹脂の硬化阻害等が起こり好ましくないだけでなく、熱伝導率、絶縁耐力低下の原因にもなる虞がある。尚、ここでいう六方晶窒化ホウ素粉末純度とは、上述した蛍光Ｘ線分析法により、測定した六方晶窒化ホウ素粉末の測定元素中、Ｂ及びＮ以外の不純物元素の含有質量割合を１００から引いた値である。 The purity of the hexagonal boron nitride powder of the present invention is preferably 99.3% by mass or more, particularly 99.6% by mass, further preferably 99.9% by mass or more. That is, if the purity of the hexagonal boron nitride powder is lower than 99.3% by mass, the resin may be inhibited from hardening due to impurities, which may not only be undesirable, but may also cause a decrease in thermal conductivity and dielectric strength. In addition, the hexagonal boron nitride powder purity referred to here is the content mass ratio of impurity elements other than B and N among the measured elements of the hexagonal boron nitride powder measured by the above-described fluorescent X-ray analysis method. Subtract from 100. value.

上記六方晶窒化ホウ素粉末の純度は、後述する実施例に示すように、蛍光Ｘ線分析法によって測定し、例えば蛍光Ｘ線分析装置としては、Ｒｉｇａｋｕ社製ＺＳＸＰｒｉｍｕｓ２（商品名）によって確認することができる。 The purity of the hexagonal boron nitride powder is measured by a fluorescent X-ray analysis method as shown in the examples described later, for example, as a fluorescent X-ray analyzer, it can be confirmed by ZSX Primus 2 (trade name) manufactured by Rigaku. can.

（窒化ホウ素粉末の製造方法）
本発明の六方晶窒化ホウ素粉末の製造方法は、特に制限されるものではないが、代表的な製造方法を例示すれば、全ホウ素中の１０Ｂの濃縮度が５０％以上である１０Ｂ濃縮含酸素ホウ素化合物、硫黄濃度が１０００～１００００ｐｐｍの範囲のカーボン源、含酸素カルシウム化合物を、含酸素ホウ素化合物に含まれるＢ源とカーボン源に含まれるＣ源の割合であるＢ／Ｃ（元素比）換算で０．７５～０．８５、含酸素ホウ素化合物とカーボン源との合計量（Ｂ２Ｏ３、Ｃ換算値）１００質量部に対して含酸素カルシウム化合物をＣａＯ換算で１０～１５質量部となる割合で混合し、該混合物を窒素雰囲気下にて１４５０～１５５０℃で４時間以上、１６５０～２１００℃で２時間以上加熱、還元窒化した後、反応生成物中に存在する窒化ホウ素以外の副生成物を酸洗浄により除去することを特徴とする六方晶窒化ホウ素粉末の製造方法が挙げられる。 (Method for producing boron nitride powder)
The method for producing the hexagonal boron nitride powder of the present invention is not particularly limited, but a typical production method is a 10 B-enriched powder having a 10 B enrichment of 50% or more in total boron. B/C (element ratio ) in terms of 0.75 to 0.85, and the total amount of the oxygen-containing boron compound and the carbon source (B 2 O 3 , C conversion value) is 100 parts by mass, and the oxygen-containing calcium compound is 10 to 15 masses in terms of CaO. parts, and the mixture is heated at 1450 to 1550° C. for 4 hours or more and at 1650 to 2100° C. for 2 hours or more in a nitrogen atmosphere for reduction nitriding, and then removes other than boron nitride present in the reaction product. A method for producing hexagonal boron nitride powder, characterized in that the by-product of is removed by acid washing.

上記製造方法において、本発明の六方晶窒化ホウ素粉末が得られる理由は明らかではないが、本発明者らは、以下のように推定している。即ち、１０Ｂ濃縮含酸素ホウ素化合物とカーボン源、窒素ガスによる後記の反応式（１）で示す還元窒化反応（１）は、還元剤であるカーボン源が酸化ホウ素を還元する還元反応（２）と窒素ガスとＢガスが反応する窒化反応（３）に分けて考える事が出来る。そして、上記還元窒化反応（１）において、含酸素カルシウム化合物は、焼成中、酸化ホウ素と複合酸化物液相を形成し、該液相が六方晶窒化ホウ素粒子の周囲を覆い、粒成長を促進させる。このようにして粒成長した六方晶窒化ホウ素粒子は、アスペクト比（長軸の長さ対厚みの比）が４～１２の粒子であり、従来の鱗片状六方晶窒化ホウ素粒子よりもアスペクト比が小さい肉厚板状粒子となり、ゆえに、平面に対して端面の割合が多いことを特徴とする。 Although the reason why the hexagonal boron nitride powder of the present invention can be obtained in the above production method is not clear, the present inventors presume as follows. That is, the reductive nitriding reaction (1) represented by the reaction formula (1) described below using a 10 B-enriched oxygenated boron compound, a carbon source, and nitrogen gas is a reduction reaction (2) in which the carbon source, which is a reducing agent, reduces boron oxide. and nitriding reaction (3) in which nitrogen gas and B gas react. In the reductive nitriding reaction (1), the oxygen-containing calcium compound forms a complex oxide liquid phase with boron oxide during firing, and the liquid phase surrounds the hexagonal boron nitride particles to promote grain growth. Let The hexagonal boron nitride particles grain-grown in this way are particles with an aspect ratio (ratio of length to thickness of major axis) of 4 to 12, and the aspect ratio is higher than that of conventional scale-like hexagonal boron nitride particles. It is characterized by small, thick plate-like particles and, therefore, a large ratio of end faces to flat surfaces.

このとき、還元剤であるカーボン源の硫黄濃度が本発明を実現する上で、重要な役割を果たす。即ち、カーボン源に含まれる硫黄分は、還元反応（２）後も、含酸素カルシウム化合物とＣａＳ等の化合物を形成し、反応物中に残存する。このとき、カーボン源は含酸素ホウ素化合物との固相反応で還元反応を引き起こすため、硫黄分も含酸素ホウ素化合物周辺に存在する事が予想され、窒化反応（３）が進行していく段階において、硫黄分が窒素分子近傍に存在していると推測される。硫黄原子と窒素原子は相互作用し易いため、粒成長中、六方晶窒化ホウ素粒子端面の窒素原子は硫黄原子と相互作用したまま、粒成長していく事が予想される。上記還元窒化反応後、酸洗浄で複合酸化物を除去する際に硫黄分も同時に除去され、このとき窒素原子がプロトン化され、六方晶窒化ホウ素粒子端面に高選択的にＮＨ２基が導入されるものと推定している。 At this time, the concentration of sulfur in the carbon source, which is the reducing agent, plays an important role in realizing the present invention. That is, the sulfur contained in the carbon source forms a compound such as CaS with the oxygen-containing calcium compound even after the reduction reaction (2) and remains in the reaction product. At this time, since the carbon source causes a reduction reaction through a solid phase reaction with the oxygen-containing boron compound, it is expected that the sulfur content will also be present around the oxygen-containing boron compound. , the sulfur content is presumed to exist in the vicinity of nitrogen molecules. Since sulfur atoms and nitrogen atoms are likely to interact with each other, it is expected that the nitrogen atoms on the end surfaces of the hexagonal boron nitride particles will grow while interacting with the sulfur atoms during grain growth. After the above reductive nitriding reaction, when the complex oxide is removed by acid washing, sulfur content is also removed at the same time, nitrogen atoms are protonated at this time, and NH2 groups are highly selectively introduced to the end faces of the hexagonal boron nitride particles. It is assumed that

また、本発明で得られた六方晶窒化ホウ素粒子は、従来の六方晶窒化ホウ素粒子の端面が湾曲して互いに繋がっているのに対して、端面が切れた構造になっている点でも特徴があり、該端面に官能基が生成し易い構造になっている。 In addition, the hexagonal boron nitride particles obtained in the present invention are characterized in that the end faces of the conventional hexagonal boron nitride particles are curved and connected to each other, while the end faces are cut. It has a structure in which a functional group is likely to be generated on the end face.

（１）Ｂ２Ｏ３＋３Ｃ＋Ｎ２→２ＢＮ＋３ＣＯ
（２）Ｂ２Ｏ３＋３Ｃ→２Ｂ（ｇ）＋３ＣＯ
（３）２Ｂ（ｇ）＋Ｎ２→２ＢＮ
（原料）
上記本発明の製造方法において、各原料は以下の通りである。 (1) B2O3+ 3C + N2 →2BN+3CO
( 2 ) B2O3+ 3C →2B(g)+3CO
(3) 2B(g)+ N2 →2BN
(material)
In the manufacturing method of the present invention, each raw material is as follows.

（１０Ｂ濃縮含酸素ホウ素化合物）
含酸素ホウ素化合物は、ホウ素の質量数が異なっていても化学的性質は変わらないため、１０Ｂ濃縮度の違いによる製造過程への影響や、得られる六方晶窒化ホウ素の熱伝導性、電気絶縁性、潤滑性、耐腐食性、離型性、高温安定性、低誘電率、化学的安定性等への影響はないことが確認されている。 ( 10 B enriched oxygenated boron compound)
Since the chemical properties of oxygen-containing boron compounds do not change even if the mass number of boron differs, the effect of the difference in the 10 B concentration on the manufacturing process, the thermal conductivity of the resulting hexagonal boron nitride, and the electrical insulation It has been confirmed that there is no effect on properties, lubricity, corrosion resistance, releasability, high temperature stability, low dielectric constant, chemical stability, etc.

そのため、上記本発明の製造方法において、原料の１０Ｂ濃縮含酸素ホウ素化合物としては、１０Ｂの存在比が５０％以上のホウ素原子を含有する化合物が制限なく使用される。上記１０Ｂ濃縮含酸素ホウ素化合物としては、例えば、１０Ｂ濃縮ホウ酸、１０Ｂ濃縮無水ホウ酸、１０Ｂ濃縮メタホウ酸、１０Ｂ濃縮過ホウ酸、１０Ｂ濃縮次ホウ酸、１０Ｂ濃縮四ホウ酸ナトリウム、１０Ｂ濃縮過ホウ酸ナトリウムなどが使用できる。一般的には、入手が容易な１０Ｂ濃縮ホウ酸、１０Ｂ濃縮酸化ホウ素が好適に用いられる。 Therefore, in the production method of the present invention, as the raw material 10 B-enriched oxygen-containing boron compound, a compound containing boron atoms in which the abundance ratio of 10 B is 50% or more is used without limitation. Examples of the 10 B-enriched oxygenated boron compounds include 10 B-enriched boric acid, 10 B-enriched boric anhydride, 10 B-enriched metaboric acid, 10 B-enriched perboric acid, 10 B-enriched hypoboric acid, 10 B-enriched tetraboric acid, Sodium borate, 10 B-enriched sodium perborate, and the like can be used. In general, easily available 10 B-enriched boric acid and 10 B-enriched boron oxide are preferably used.

なお、得られる窒化ホウ素粉末の熱中性子吸収性能の観点から、原料の１０Ｂ濃縮含酸素ホウ素化合物について、１０Ｂの濃縮度は５０％以上が好ましく、９０％以上がより好ましく、９５％以上が更に好ましく、９９％以上がより更に好ましい。 From the viewpoint of the thermal neutron absorption performance of the obtained boron nitride powder, the concentration of 10 B in the raw material 10 B-enriched oxygen-containing boron compound is preferably 50% or more, more preferably 90% or more, and 95% or more. More preferably, 99% or more is even more preferable.

また、前記１０Ｂ濃縮含酸素ホウ素化合物は、単独で用いても良いし、複数組み合わせても良い。複数組み合わせる場合、使用する含酸素ホウ素化合物における１０Ｂの濃縮度を勘案し、該含酸素ホウ素化合物の量を適宜調整することにより、上記存在比の範囲を満足させることができる。例えば、上記濃縮度の範囲になるように、１０Ｂの濃縮度の大きい含酸素ホウ素化合物と、１０Ｂの濃縮度の小さい含酸素ホウ素化合物とを上記範囲内になるように混合し、その割合を調整してもよい。 Further, the 10 B-enriched oxygenated boron compounds may be used singly or in combination. When a plurality of compounds are combined, the above abundance ratio range can be satisfied by appropriately adjusting the amount of the oxygen-containing boron compound in consideration of the concentration of 10 B in the oxygen-containing boron compound to be used. For example, an oxygen-containing boron compound having a high concentration of 10 B and an oxygen-containing boron compound having a low concentration of 10 B are mixed so as to fall within the above range, and the ratio thereof is may be adjusted.

なお、市販の１０Ｂ濃縮含酸素ホウ素化合物としては、濃縮度９５％以上の１０Ｂ濃縮ホウ酸（ステラケミファ株式会社製、ヤマナカセラダイン株式会社製）が、濃縮度９９％の１０Ｂ濃縮ホウ酸（Cambridge Isotope Laboratories, Inc.製）が入手可能である。 As commercially available 10 B enriched oxygenated boron compounds, 10 B enriched boric acid with a concentration of 95% or more (manufactured by Stella Chemifa Co., Ltd., Yamanaka Celadine Co., Ltd.), 10 B enriched boron with a concentration of 99% Acid is available from Cambridge Isotope Laboratories, Inc.

また、使用する１０Ｂ濃縮含酸素ホウ素化合物の平均粒子径も特に限定されないが、操作性及び還元反応制御の観点から、３０～５００μｍが好ましく、５０～４００μｍがより好ましく、１００～２５０μｍが更に好ましい。即ち、１０Ｂ濃縮含酸素ホウ素化合物の平均粒子径が３０μｍより大きいものを使用することによって、取扱いが容易となる。しかし、５００μｍを超えると１０Ｂ濃縮含酸素ホウ素化合物の還元反応が進行し難くなる虞がある。 The average particle size of the 10 B-enriched oxygenated boron compound to be used is also not particularly limited, but is preferably 30 to 500 μm, more preferably 50 to 400 μm, and even more preferably 100 to 250 μm from the viewpoint of operability and reduction reaction control. . That is, use of a 10 B-enriched oxygenated boron compound having an average particle size of greater than 30 μm facilitates handling. However, if it exceeds 500 μm, the reduction reaction of the 10 B-enriched oxygenated boron compound may be difficult to proceed.

（含酸素カルシウム化合物）
前記したように、含酸素カルシウム化合物は、１０Ｂ濃縮含酸素ホウ素化合物と複合酸化物を形成することで、高融点の複合酸化物を形成し、窒化ホウ素粒子の粒成長触媒となるだけでなく、カーボン源中の硫黄分と反応し、硫黄分の揮散防止剤としても作用する。 (Oxygen-containing calcium compound)
As described above, the oxygen-containing calcium compound forms a composite oxide with a 10 B-enriched oxygen-containing boron compound to form a composite oxide with a high melting point, which not only serves as a grain growth catalyst for boron nitride particles. , reacts with the sulfur content in the carbon source, and also acts as an anti-volatilization agent for the sulfur content.

本発明の製造方法において、結晶化触媒及び１０Ｂ濃縮含酸素ホウ素化合物及び硫黄分の揮散防止剤として使用される含酸素カルシウム化合物としては、公知のものが特に制限無く使用されるが、特に、酸素とカルシウムが含まれる含酸素カルシウム化合物が好適に使用される。含酸素カルシウム化合物としては、例えば、炭酸カルシウム、炭酸水素カルシウム、水酸化カルシウム、酸化カルシウム、硝酸カルシウム、硫酸カルシウム、リン酸カルシウム、シュウ酸カルシウム等が挙げられる。その中でも含酸素カルシウム化合物が好適に使用出来る。含酸素カルシウム化合物としては、例えば、炭酸カルシウム、炭酸水素カルシウム、水酸化カルシウム、酸化カルシウム、硝酸カルシウム、硫酸カルシウム、リン酸カルシウム、シュウ酸カルシウム等を使用することが出来、これら２種類以上を混合して使用することも可能である。その中でも、酸化カルシウム、炭酸カルシウムを使用するのが好ましい。 In the production method of the present invention, as the crystallization catalyst, the 10 B-enriched oxygenated boron compound, and the oxygenated calcium compound used as the sulfur volatilization inhibitor, known oxygenated calcium compounds can be used without particular limitation. Oxygenated calcium compounds containing oxygen and calcium are preferably used. Examples of oxygen-containing calcium compounds include calcium carbonate, calcium hydrogen carbonate, calcium hydroxide, calcium oxide, calcium nitrate, calcium sulfate, calcium phosphate, calcium oxalate and the like. Among them, an oxygen-containing calcium compound can be preferably used. As the oxygen-containing calcium compound, for example, calcium carbonate, calcium hydrogen carbonate, calcium hydroxide, calcium oxide, calcium nitrate, calcium sulfate, calcium phosphate, calcium oxalate, etc. can be used. It is also possible to use Among them, it is preferable to use calcium oxide and calcium carbonate.

上記含酸素カルシウム化合物は、２種類以上を混合して使用することも可能である。また、上記含酸素カルシウム化合物の平均粒子径は、平均粒子径０．０１～２００μｍが好ましく、０．０５～１２０μｍがより好ましく、０．１～８０μｍが特に好ましい。 Two or more kinds of the oxygen-containing calcium compounds can be mixed and used. Moreover, the average particle size of the oxygen-containing calcium compound is preferably 0.01 to 200 μm, more preferably 0.05 to 120 μm, and particularly preferably 0.1 to 80 μm.

（カーボン源）
本発明の製造方法において、カーボン源は、還元剤として作用するものであり、硫黄を特定量含有するものを使用することが、硫黄を反応に確実に寄与せしめるために好ましい。また、上記硫黄をカーボン源とは別に硫黄単体として添加することも可能であるが、カーボン源と近接している方が好ましいため、予め硫黄とカーボン源を、例えばボールミル等で予混合しておく事が好ましい。上記予混合を省略すると、反応時における揮散が激しく、大量の添加が必要となるばかりでなく、反応装置の排気系に硫黄が飛散し、閉塞する虞がある。 (carbon source)
In the production method of the present invention, the carbon source acts as a reducing agent, and it is preferable to use one containing a specific amount of sulfur in order to ensure that sulfur contributes to the reaction. In addition, it is possible to add the above sulfur as elemental sulfur separately from the carbon source, but it is preferable that the sulfur is in close proximity to the carbon source. things are preferable. If the premixing is omitted, volatilization will be intense during the reaction, and not only will a large amount of addition be required, but sulfur will also fly into the exhaust system of the reactor, possibly clogging it.

上記カーボン源に含まれる硫黄濃度は１５００～８０００ｐｐｍが好ましく、２０００～６０００ｐｐｍが更に好ましい。即ち、該硫黄濃度が、１０００ｐｐｍ以下であると、得られる六方晶窒化ホウ素粉末のＮＨ２基の非対称収縮振動ピークが減少し、１００００ｐｐｍ以上であると、不純物として硫黄が残留する虞がある。 The concentration of sulfur contained in the carbon source is preferably 1500-8000 ppm, more preferably 2000-6000 ppm. That is, when the sulfur concentration is 1000 ppm or less, the asymmetric contraction vibration peak of the NH 2 group of the obtained hexagonal boron nitride powder is reduced, and when it is 10000 ppm or more, sulfur may remain as an impurity.

また、カーボン源は、反応性の高い非晶質炭素が好ましく、更に、工業的に品質制御されている点で、カーボンブラックが特に好適に使用される。 Further, the carbon source is preferably highly reactive amorphous carbon, and carbon black is particularly preferably used because the quality is industrially controlled.

更に、上記カーボン源の平均粒子径は、０．０２～３μｍが好ましく、０．０２～２μｍがより好ましく、０．０５～１μｍが特に好ましい。即ち、該カーボン源の平均粒子径を３μｍ以下とすることにより、カーボン源の反応性が高くなり、また、０．０１μｍ以上とすることにより、取り扱いが容易となる。 Furthermore, the average particle size of the carbon source is preferably 0.02 to 3 μm, more preferably 0.02 to 2 μm, particularly preferably 0.05 to 1 μm. That is, by setting the average particle size of the carbon source to 3 μm or less, the reactivity of the carbon source is increased, and by setting the average particle size to 0.01 μm or more, handling becomes easy.

（原料の調製）
本発明において、還元窒化反応は、カーボン源と窒素の供給により実施されるが、目的とする六方晶窒化ホウ素粉末を効果的に得るためには、１０Ｂ濃縮含酸素ホウ素化合物と複合酸化物に含まれるＢ源とカーボン源との割合は、Ｂ／Ｃ（元素比）換算で０．７５～０．８５、好ましくは０．７７～０．８３とすることが必要である。即ち、該モル比が０．８５を超えると、還元されずに揮散するホウ素化合物の割合が増加し、収率が低下するばかりでなく、上記揮散成分により、製造ラインに悪影響を及ぼす。また、該モル比が０．７５以下では、未反応の酸化ホウ素量が少なく、還元窒化後、硫黄分を含む含酸素カルシウム化合物と形成する、上記複合酸化物形成量が少なく、六方晶窒化ホウ素粒子の周囲を均一に覆う事が困難となり、目的とするＮＨ２基量の多い六方晶窒化ホウ素粉末を得る事が困難となる。 (Preparation of raw materials)
In the present invention, the reductive nitriding reaction is carried out by supplying a carbon source and nitrogen. In order to effectively obtain the desired hexagonal boron nitride powder, The ratio of the B source and the carbon source contained should be 0.75 to 0.85, preferably 0.77 to 0.83 in terms of B/C (element ratio). That is, if the molar ratio exceeds 0.85, the proportion of the boron compound that volatilizes without being reduced increases, and not only does the yield decrease, but the volatilized components adversely affect the production line. In addition, when the molar ratio is 0.75 or less, the amount of unreacted boron oxide is small, the amount of the above-mentioned composite oxide formed with the oxygen-containing calcium compound containing sulfur after reduction nitridation is small, and the hexagonal boron nitride It becomes difficult to uniformly cover the periphery of the particles, making it difficult to obtain the desired hexagonal boron nitride powder with a large amount of NH 2 groups.

本発明において、目的とする六方晶窒化ホウ素粉末を効果的に得るためには、１０Ｂ濃縮含酸素ホウ素化合物とカーボン源との合計量（Ｂ２Ｏ３、Ｃ換算値）１００質量部に対して含酸素カルシウム化合物をＣａＯ換算で１０～１５質量部となる割合で混合することが必要である。このとき、ＣａＯ換算質量部が１０質量部未満では、六方晶窒化ホウ素粒子周囲を覆うほどの、酸化ホウ素と形成する上記複合酸化物量を形成することが困難となり、好ましくない。また、還元されずに揮散するホウ素化合物の割合が増加し、収率が低下するばかりでなく、上記揮散成分により、製造ラインに悪影響を及ぼし好ましくない。ＣａＯ換算質量部が１５質量部を超えると、カルシウム由来の不純物が残存する虞があるだけでなく、板状六方晶窒化ホウ素単粒子が粒成長し難く好ましくない。 In the present invention, in order to effectively obtain the desired hexagonal boron nitride powder, the total amount of the 10 B-enriched oxygen-containing boron compound and the carbon source (B 2 O 3 , converted to C) is 100 parts by mass. It is necessary to mix the oxygen-containing calcium compound at a ratio of 10 to 15 parts by mass in terms of CaO. At this time, if the CaO-equivalent mass is less than 10 parts by mass, it is difficult to form an amount of the above-described composite oxide formed with boron oxide to cover the surroundings of the hexagonal boron nitride particles, which is not preferable. In addition, the proportion of the boron compound that volatilizes without being reduced increases, which not only lowers the yield, but also adversely affects the production line due to the volatilized component, which is undesirable. If the CaO-equivalent mass exceeds 15 parts by mass, not only is there a possibility that calcium-derived impurities may remain, but grain growth of plate-like hexagonal boron nitride single particles is difficult, which is undesirable.

本発明の製造方法において、上記の各原料を含む混合物の反応への供給形態は特に制限されず、粉末状のままでもよいが、造粒体を形成して行ってもよい。 In the production method of the present invention, the form in which the mixture containing the above raw materials is supplied to the reaction is not particularly limited, and may be in the form of powder, or may be carried out after forming granules.

本発明の製造方法において、前記原料の混合方法は特に制限されず、振動ミル、ビーズミル、ボールミル、ヘンシェルミキサー、ドラムミキサー、振動攪拌機、Ｖ字混合機等の一般的な混合機が使用可能である。 In the production method of the present invention, the method of mixing the raw materials is not particularly limited, and general mixers such as vibration mills, bead mills, ball mills, Henschel mixers, drum mixers, vibration stirrers, and V-shaped mixers can be used. .

また、造粒を行う場合の造粒方法も、必要に応じてバインダーを使用し、押出造粒、転動造粒、コンパクターによる造粒など、公知の方法により実施することができる。この場合、造粒体の大きさは、５～１０ｍｍ程度が好適である。 Also, the granulation method for granulation can be carried out by known methods such as extrusion granulation, tumbling granulation, and granulation with a compactor, using a binder as necessary. In this case, the size of the granules is preferably about 5 to 10 mm.

（還元窒化）
本発明の窒化ホウ素製造方法において、反応系への窒素源の供給は、公知の手段によって形成することが出来る。例えば、後に例示した反応装置の反応系内に窒素ガスを流通させる方法が最も一般的である。また、使用する窒素源としては、上記窒素ガスに限らず、還元窒化反応において窒化が可能なガスであれば特に制限されない。具体的には、前記窒素ガスの他、アンモニアガスを使用することも可能である。また、窒素ガス、アンモニアガスに、水素、アルゴン、ヘリウム等の非酸化性ガスを混合したガスも使用可能である。 (reduction nitriding)
In the boron nitride production method of the present invention, the supply of the nitrogen source to the reaction system can be formed by known means. For example, the most common method is to pass nitrogen gas through the reaction system of the reactor illustrated later. Further, the nitrogen source to be used is not limited to the nitrogen gas described above, and is not particularly limited as long as it is a gas capable of nitriding in the reductive nitriding reaction. Specifically, ammonia gas can be used in addition to the nitrogen gas. A gas obtained by mixing a non-oxidizing gas such as hydrogen, argon, or helium with nitrogen gas or ammonia gas can also be used.

また、本発明の六方晶窒化ホウ素粉末を得るためには、１４５０～１５５０℃で５時間以上、１６５０～２１００℃の温度で２時間以上反応させる事が重要である。 In order to obtain the hexagonal boron nitride powder of the present invention, it is important to carry out the reaction at a temperature of 1450 to 1550° C. for 5 hours or longer and at a temperature of 1650 to 2100° C. for 2 hours or longer.

即ち、１４５０～１５５０℃の還元窒化反応が起こり始める温度域で５時間以上保持する事で、六方晶系平面が層状に積層し易くなり、粒子端面のＮＨ２基量が多く、アスペクト比の低い六方晶窒化ホウ素粒子を高選択的に得る事が可能となる。１４５０℃以下では還元窒化反応速度が遅く、１５５０℃では速過ぎるため好ましくなく、５時間以下では反応時間が不十分であり、好ましくない。 That is, by holding for 5 hours or more in the temperature range of 1450 to 1550 ° C. where the reductive nitriding reaction starts to occur, the hexagonal planes are easily laminated in layers, the amount of NH 2 groups on the particle end faces is large, and the aspect ratio is low. It becomes possible to obtain hexagonal boron nitride particles with high selectivity. At 1450° C. or less, the reductive nitriding reaction rate is slow, and at 1550° C., it is too fast, which is not preferable, and at 5 hours or less, the reaction time is insufficient, which is not preferable.

また、高結晶性の六方晶窒化ホウ素粒子を得るために、還元窒化反応における最高加熱温度は、通常１６５０℃以上、好ましくは、１７００～２１００℃、更に好ましくは１８００～２０００℃の温度で２時間以上加熱する条件を採用することが必要である。即ち、かかる温度が１６５０℃未満では還元窒化反応が未進行、且つ、結晶性の高い六方晶窒化ホウ素粒子を得ることが困難であり、２１００℃を超える温度では、効果が頭打ちとなり、経済的に不利である。 Further, in order to obtain highly crystalline hexagonal boron nitride particles, the maximum heating temperature in the reductive nitriding reaction is usually 1650° C. or higher, preferably 1700 to 2100° C., more preferably 1800 to 2000° C. for 2 hours. It is necessary to adopt the above heating conditions. That is, if the temperature is less than 1650°C, the reductive nitriding reaction does not proceed and it is difficult to obtain hexagonal boron nitride particles with high crystallinity. disadvantageous.

本発明の六方晶窒化ホウ素粉末の製造方法は、反応雰囲気制御の可能な公知の反応装置を使用して行うことができる。例えば、高周波誘導加熱やヒーター加熱により加熱処理を行う雰囲気制御型高温炉が挙げられ、バッチ炉の他、プッシャー式トンネル炉、竪型反応炉等の連続炉も使用可能である。 The method for producing the hexagonal boron nitride powder of the present invention can be carried out using a known reactor capable of controlling the reaction atmosphere. For example, an atmosphere-controlled high-temperature furnace in which heat treatment is performed by high-frequency induction heating or heater heating can be used. In addition to batch furnaces, continuous furnaces such as pusher-type tunnel furnaces and vertical reactors can also be used.

（酸洗浄）
本発明の製造方法において、上述の還元窒化によって得られる反応生成物は、六方晶窒化ホウ素粉末の他に、酸化ホウ素―酸化カルシウムから成る複合酸化物等の不純物が存在するため、酸を用いて洗浄することが好ましい。かかる酸洗浄の方法は特に制限されず、公知の方法が制限無く採用される。例えば、窒化処理後に得られた副生成物含有窒化ホウ素を解砕して容器に投入し、該不純物を含有する六方晶窒化ホウ素粉末の５～１０倍量の希塩酸（１０～２０質量％ＨＣｌ）を加え、４時間以上接触せしめる方法などが挙げられる。 (Acid cleaning)
In the production method of the present invention, the reaction product obtained by the above-described reductive nitriding contains impurities such as boron oxide-calcium oxide composite oxides in addition to the hexagonal boron nitride powder. Washing is preferred. The method of acid washing is not particularly limited, and known methods are employed without limitation. For example, by-product-containing boron nitride obtained after nitriding treatment is pulverized and put into a container, and 5 to 10 times the amount of hexagonal boron nitride powder containing the impurity is diluted hydrochloric acid (10 to 20% by mass HCl). is added and kept in contact for 4 hours or longer.

上記酸洗浄時に用いる酸としては、塩酸以外にも、硝酸、硫酸、酢酸等を用いることも可能である。 In addition to hydrochloric acid, nitric acid, sulfuric acid, acetic acid, etc. may be used as the acid used for the acid cleaning.

上記酸洗浄の後、残存する酸を洗浄する目的で、純水を用いて洗浄する。上記洗浄の方法としては、上記酸洗浄時の酸をろ過した後、使用した酸と同量の純水に酸洗浄した窒化ホウ素を分散させ、再度ろ過する。 After the acid cleaning, pure water is used to clean the remaining acid. As the cleaning method, after filtering the acid used for the acid cleaning, the acid-cleaned boron nitride is dispersed in the same amount of pure water as the acid used, and filtered again.

（乾燥）
上記、酸洗浄、水洗浄後の、含水塊状物を乾燥条件としては、５０～２５０℃の大気、もしくは減圧下での乾燥が好ましい。乾燥時間は、特に指定しないが、含水率が０％に限りなく近づくまで乾燥することが好ましい。 (dry)
As drying conditions for the water-containing mass after acid washing and water washing, drying in the air at 50 to 250° C. or under reduced pressure is preferable. Although the drying time is not specified, it is preferable to dry until the moisture content approaches 0%.

（分級）
乾燥後の窒化ホウ素粉末は、必要に応じて、粗解砕、篩等による粗粒除去、気流分級等による微粉除去を行ってもよい。 (Classification)
If necessary, the dried boron nitride powder may be subjected to coarse pulverization, removal of coarse particles by a sieve or the like, and removal of fine particles by air classification or the like.

（窒化ホウ素粉末の用途）
本発明の窒化ホウ素粉末の用途は、特に限定されず、公知の用途に特に制限無く適用可能である。好適に使用される用途を例示するならば、中性子吸収性能付与、電気絶縁性向上、熱伝導性付与等の目的で樹脂に充填剤として使用する用途が挙げられる。上記窒化ホウ素粉末の用途において、得られる樹脂組成物は、優れた中性子吸収性能、高い電気絶縁性や熱伝導性を有する。 (Uses of boron nitride powder)
The use of the boron nitride powder of the present invention is not particularly limited, and it can be applied to known uses without particular limitations. Examples of suitable uses include use as a filler in resins for the purpose of imparting neutron absorption performance, improving electrical insulation, imparting thermal conductivity, and the like. In the application of the boron nitride powder, the resulting resin composition has excellent neutron absorption performance, high electrical insulation and thermal conductivity.

本発明の樹脂組成物は制限無く公知の用途に使用することが出来るが、後述する樹脂と混合し、樹脂組成物あるいは成形体とすることでポリマー系放熱シートやフェイズチェンジシート等のサーマルインターフェイスマテリアル、放熱テープ、放熱グリース、放熱接着剤、ギャップフィラー等の有機系放熱シート類、放熱塗料、放熱コート等の放熱塗料類、ＰＷＢベース樹脂基板、ＣＣＬベース樹脂基板等の放熱樹脂基板、アルミベース基板、銅ベース基板等のメタルベース基板の絶縁層、パワーデバイス用封止材等の用途に好ましく用いることが出来る。 The resin composition of the present invention can be used for known applications without limitation, but it can be mixed with a resin described later to form a resin composition or a molded product, such as a thermal interface material such as a polymer heat dissipation sheet or a phase change sheet. , heat dissipation tape, heat dissipation grease, heat dissipation adhesive, organic heat dissipation sheets such as gap filler, heat dissipation paint, heat dissipation paint such as heat dissipation coat, heat dissipation resin substrate such as PWB base resin substrate, CCL base resin substrate, aluminum base substrate , insulating layers of metal base substrates such as copper base substrates, sealing materials for power devices, and the like.

前記樹脂としては、ポリオレフィン、塩化ビニル樹脂、メタクリル酸メチル樹脂、ナイロン、フッ素樹脂等の熱可塑性樹脂、エポキシ樹脂、フェノール樹脂、尿素樹脂、メラミン樹脂、不飽和ポリエステル樹脂、ケイ素樹脂、ビスマレイミドトリアジン樹脂、ウレタン樹脂等の熱硬化性樹脂、合成ゴムなどが挙げられる。 Examples of the resin include thermoplastic resins such as polyolefin, vinyl chloride resin, methyl methacrylate resin, nylon, fluorine resin, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicone resin, and bismaleimide triazine resin. , thermosetting resin such as urethane resin, and synthetic rubber.

また、上記樹脂組成物には、必要に応じて樹脂組成物の配合剤として公知の重合開始剤、硬化剤、重合禁止剤、重合遅延剤、カップリング剤、可塑剤、紫外線吸収剤、顔料、染料、抗菌剤、有機フィラー、有機無機複合フィラーなどの公知の添加剤を含んでもよい。また、本発明の効果を損なわない範囲で他の無機フィラーを含んでいてもよい。 In addition, the resin composition may optionally contain known polymerization initiators, curing agents, polymerization inhibitors, polymerization retarders, coupling agents, plasticizers, ultraviolet absorbers, pigments, Known additives such as dyes, antibacterial agents, organic fillers, and organic-inorganic composite fillers may also be included. In addition, other inorganic fillers may be contained within a range that does not impair the effects of the present invention.

また、本発明の窒化ホウ素粉末は、立方晶窒化ホウ素や窒化ホウ素成型品等の窒化ホウ素加工品製品の原料、エンジニアリングプラスチックへの核剤、フェーズチェンジマテリアル、固体状または液体状のサーマルインターフェイスマテリアル、溶融金属や溶融ガラス成形型の離型剤、化粧品、複合セラミックス原料等の用途にも使用することができる。 Further, the boron nitride powder of the present invention is used as a raw material for processed boron nitride products such as cubic boron nitride and boron nitride molded products, as a nucleating agent for engineering plastics, as a phase change material, as a solid or liquid thermal interface material, It can also be used as a release agent for molds for molten metals and molten glass, cosmetics, raw materials for composite ceramics, and the like.

以下、本発明を実施例により更に詳細に説明するが、本発明は、これらの実施例に限定されるものではない。 EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

尚、実施例において、各測定は、以下の方法により測定した値である。 In addition, in the examples, each measurement is a value measured by the following method.

［六方晶窒化ホウ素粉末の同位体存在比］
得られた六方晶窒化ホウ素粉末について、アルバック・ファイ株式会社製：ＰＨＩ ＡＤＥＰＴ－１０１０を用いて同位体存在比の分析を行った。マススペクトルの１０Ｂと１１Ｂのカウントの比から窒化ホウ素粉末の全ホウ素中の１０Ｂの存在比を確認した。 [Isotope abundance ratio of hexagonal boron nitride powder]
The obtained hexagonal boron nitride powder was analyzed for the isotope abundance ratio using PHI ADEPT-1010 manufactured by ULVAC-PHI, Inc. From the ratio of 10 B and 11 B counts in the mass spectrum, the abundance ratio of 10 B in the total boron of the boron nitride powder was confirmed.

［六方晶窒化ホウ素粉末の赤外吸収スペクトル］
得られた六方晶窒化ホウ素粉末について、アジレント・テクノロジー株式会社製：ＦＴＳ－３０００を用いて、拡散反射赤外分光測定を行った。試料の前処理として２００℃、減圧下で２時間乾燥処理を行った。測定カップに試料を詰め測定した。分解能は４ｃｍ－１、測定範囲は～４０００ｃｍ－１、積算回数は６４回で行った。得られた六方晶窒化ホウ素粉末の表面官能基が現れる３１００～３８００ｃｍ－１のピークの有無、最高吸収ピークを確認した。また、上述した方法を用いて、８００ｃｍ－１付近の吸収ピーク高さＡと３５３０～３５９０ｃｍ－１の最高吸収ピーク高さＢの比Ｂ／Ａを求めた。 [Infrared absorption spectrum of hexagonal boron nitride powder]
The obtained hexagonal boron nitride powder was subjected to diffuse reflectance infrared spectroscopy using FTS-3000 manufactured by Agilent Technologies. As a pretreatment of the sample, drying treatment was performed at 200° C. under reduced pressure for 2 hours. A sample was packed in a measuring cup and measured. The resolution was 4 cm −1 , the measurement range was up to 4000 cm −1 , and the number of integrations was 64. The presence or absence of a peak at 3100 to 3800 cm −1 where the surface functional groups appear in the obtained hexagonal boron nitride powder and the highest absorption peak were confirmed. Also, the ratio B/A between the absorption peak height A near 800 cm −1 and the highest absorption peak height B between 3530 and 3590 cm −1 was determined using the method described above.

［六方晶窒化ホウ素粉末の比表面積（ｍ２／ｇ）］
得られた六方晶窒化ホウ素粉末について、マウンテック社製：Ｍａｃｓｏｒｂ ＨＭ ｍｏｄｅｌ－１２０１を用いて比表面積を測定した。 [Specific surface area of hexagonal boron nitride powder (m 2 /g)]
The specific surface area of the obtained hexagonal boron nitride powder was measured using Macsorb HM model-1201 manufactured by Mountech.

［六方晶窒化ホウ素粉末中に含まれる酸素濃度（質量％）］
得られた六方晶窒化ホウ素粉末について、酸素濃度を、ＨＯＲＩＢＡ社製ＥＭＧＡ－６２０Ｗを用いて測定した。 [Oxygen concentration contained in hexagonal boron nitride powder (% by mass)]
The oxygen concentration of the obtained hexagonal boron nitride powder was measured using EMGA-620W manufactured by HORIBA.

［六方晶窒化ホウ素粉末の粒度分布の累積体積頻度５０％の粒径Ｄ１（μｍ）］
得られた六方晶窒化ホウ素粉末について、ＨＯＲＩＢＡ社製：ＬＡ－９５０Ｖ２を用いて粒度分布の累積体積頻度５０％の粒径（Ｄ１）を測定した。測定はエタノール溶媒中に窒化ホウ素粉末を分散させ、測定した。得られた粒度分布の累積体積頻度５０％の粒径を（Ｄ１）とした。 [Particle size D1 (μm) at cumulative volume frequency of 50% in particle size distribution of hexagonal boron nitride powder]
For the obtained hexagonal boron nitride powder, the particle size (D1) at a cumulative volume frequency of 50% in the particle size distribution was measured using LA-950V2 manufactured by HORIBA. The measurement was carried out by dispersing boron nitride powder in an ethanol solvent. The particle size at a cumulative volume frequency of 50% in the obtained particle size distribution was defined as (D1).

［六方晶窒化ホウ素粉末純度（質量％）］
得られた六方晶窒化ホウ素粉末について、Ｒｉｇａｋｕ社製ＺＳＸ Ｐｒｉｍｕｓ２を用いて六方晶窒化ホウ素粉末純度を測定した。六方晶窒化ホウ素粉末純度とは、上述した蛍光Ｘ線分析法により、測定した六方晶窒化ホウ素粉末の測定元素中、Ｂ及びＮ以外の不純物元素の含有質量割合を１００から引いた値である。 [Hexagonal boron nitride powder purity (mass%)]
The obtained hexagonal boron nitride powder was measured for hexagonal boron nitride powder purity using ZSX Primus 2 manufactured by Rigaku. The hexagonal boron nitride powder purity is a value obtained by subtracting from 100 the content mass ratio of impurity elements other than B and N among the measured elements of the hexagonal boron nitride powder measured by the above-described fluorescent X-ray analysis method.

［原料カーボンブラックの硫黄濃度（ｐｐｍ）］
原料カーボンブラックの硫黄濃度は吉田科学器械社製ＱＳ－ＡＣ１を用いて測定した。 [Sulfur concentration of raw carbon black (ppm)]
The sulfur concentration of raw material carbon black was measured using QS-AC1 manufactured by Yoshida Scientific Instruments Co., Ltd.

実施例１
１０Ｂの濃縮度が９０％の１０Ｂ濃縮ホウ酸３４６ｇ、硫黄濃度３５００ｐｐｍのカーボンブラック８２ｇ、炭酸カルシウム５０ｇを、ボールミルを使用して混合した。該混合物の（Ｂ／Ｃ）元素比換算は０．８２、１０Ｂ濃縮含酸素ホウ素化合物、カーボン源、含酸素カルシウム化合物の、Ｂ２Ｏ３、Ｃ換算質量合計量１００質量部に対する上記含酸素カルシウム化合物のＣａＯ換算質量含有割合は１０質量部である。該混合物１００ｇを、黒鉛製タンマン炉を用い、窒素ガス雰囲気下、１５００℃で８時間、１８５０℃で４時間保持することで窒化処理した。窒化処理品を蛍光Ｘ線分析測定したところ、窒化処理品の硫黄濃度が２００ｐｐｍであり、硫黄分の残留が確認された。 Example 1
346 g of 10 B enriched boric acid with a 10 B enrichment of 90%, 82 g of carbon black with a sulfur concentration of 3500 ppm and 50 g of calcium carbonate were mixed using a ball mill. The ( B /C) element ratio conversion of the mixture is 0.82 , and the oxygen - containing The CaO equivalent mass content ratio of the calcium compound is 10 parts by mass. 100 g of the mixture was subjected to nitriding treatment by holding at 1500° C. for 8 hours and at 1850° C. for 4 hours in a nitrogen gas atmosphere using a graphite Tammann furnace. When the nitriding product was measured by fluorescent X-ray analysis, the sulfur concentration of the nitriding product was 200 ppm, and residual sulfur was confirmed.

次いで、副生成物含有窒化ホウ素を解砕して容器に投入し、該副生成物含有窒化ホウ素の５倍量の塩酸（７質量％ＨＣｌ）を加え、回転数７００ｒｐｍで２４時間撹拌した。該酸洗浄の後、酸をろ過し、使用した酸と同量の純水に、ろ過して得られた窒化ホウ素を分散させ、再度ろ過した。この操作を６回繰り返した後、２００℃で６時間真空乾燥させた。 Next, the boron nitride containing the by-product was pulverized and put into a container, and hydrochloric acid (7% by mass HCl) was added in an amount five times the amount of the boron nitride containing the by-product, and the mixture was stirred at a rotation speed of 700 rpm for 24 hours. After the acid washing, the acid was filtered, and the boron nitride obtained by filtration was dispersed in the same amount of pure water as the acid used, and filtered again. After repeating this operation 6 times, it was vacuum-dried at 200° C. for 6 hours.

乾燥後に得られた粉末を目開き１２０μｍの篩にかけて、白色の粉末を得た。得られた白色粉末は、Ｘ線回折測定により、六方晶窒化ホウ素と同定された。得られた六方晶窒化ホウ素粉末の全ホウ素中の１０Ｂの存在比、拡散反射赤外吸収スペクトル、酸素濃度、比表面積、平均粒径、純度を上述した方法で測定し、表２に示した。 The powder obtained after drying was passed through a sieve with an opening of 120 μm to obtain a white powder. The resulting white powder was identified as hexagonal boron nitride by X-ray diffraction measurement. The abundance ratio of 10 B in the total boron of the obtained hexagonal boron nitride powder, the diffuse reflection infrared absorption spectrum, the oxygen concentration, the specific surface area, the average particle size, and the purity were measured by the methods described above, and are shown in Table 2. .

実施例１において得られた六方晶窒化ホウ素粉末について、倍率２０００倍で観察した６０μｍ×４０μｍ四方の複数のＳＥＭ観察像を画像解析装置（Ａ像くん：旭化成エンジニアリング株式会社製）により解析し、異なる単粒子を５００個無作為に選び、長軸の長さと厚み方向の長さを測定し、長軸の長さ／厚み方向の長さよりアスペクト比を算出したところ、平均アスペクト比は７．３であった。 For the hexagonal boron nitride powder obtained in Example 1, multiple SEM observation images of 60 μm × 40 μm square observed at a magnification of 2000 were analyzed with an image analysis device (Azo-kun: manufactured by Asahi Kasei Engineering Co., Ltd.). 500 single particles were randomly selected, the length of the major axis and the length in the thickness direction were measured, and the aspect ratio was calculated from the length of the major axis/length in the thickness direction. The average aspect ratio was 7.3. there were.

実施例２
原料カーボンブラックの硫黄濃度を８０００ｐｐｍ、（Ｂ／Ｃ）元素比換算を０．７９、１０Ｂ濃縮含酸素ホウ素化合物、カーボン源、含酸素カルシウム化合物の、Ｂ２Ｏ３、Ｃ換算質量合計量１００質量部に対する上記含酸素カルシウム化合物のＣａＯ質量換算含有割合を１０．５質量部とした以外は実施例１と同様にした。各条件、測定値を表１、２に示した。 Example 2
The sulfur concentration of the raw material carbon black is 8000 ppm, the (B/C) element ratio conversion is 0.79, the total mass of the 10 B enriched oxygenated boron compound, the carbon source, and the oxygenated calcium compound in terms of B 2 O 3 and C is 100 The procedure was the same as in Example 1, except that the content ratio of the oxygen-containing calcium compound in terms of CaO mass relative to the mass parts was changed to 10.5 parts by mass. Tables 1 and 2 show the conditions and measured values.

実施例３
原料カーボンブラックの硫黄濃度を１２００ｐｐｍ、（Ｂ／Ｃ）元素比換算を０．７８、１０Ｂ濃縮含酸素ホウ素化合物、カーボン源、含酸素カルシウム化合物の、Ｂ２Ｏ３、Ｃ換算質量合計量１００質量部に対する上記含酸素カルシウム化合物のＣａＯ質量換算含有割合を１１質量部、還元窒化最高温度を１８００℃とした以外は実施例１と同様にした。各条件、測定値を表１、２に示した。 Example 3
The sulfur concentration of the raw material carbon black is 1200 ppm, the (B/C) element ratio conversion is 0.78, the total mass of the 10 B-enriched oxygenated boron compound, the carbon source, and the oxygenated calcium compound in terms of B 2 O 3 and C is 100 The procedure was the same as in Example 1, except that the content ratio of the oxygen-containing calcium compound in terms of CaO mass relative to the mass parts was 11 parts by mass, and the maximum reductive nitriding temperature was 1800°C. Tables 1 and 2 show the conditions and measured values.

実施例４
（Ｂ／Ｃ）元素比換算を０．７５、１０Ｂ濃縮含酸素ホウ素化合物、カーボン源、含酸素カルシウム化合物の、Ｂ２Ｏ３、Ｃ換算質量合計量１００質量部に対する上記含酸素カルシウム化合物のＣａＯ質量換算含有割合を１２質量部、還元窒化最高温度を１９５０℃とした以外は実施例１と同様にした。各条件、測定値を表１、２に示した。 Example 4
(B/C) element ratio conversion of 0.75, 10 B-enriched oxygen-containing boron compound, carbon source, oxygen-containing calcium compound, B 2 O 3 , C conversion mass total amount of 100 parts by mass of the oxygen-containing calcium compound The procedure was the same as in Example 1, except that the content ratio in terms of CaO mass was 12 parts by mass and the maximum temperature for reductive nitriding was 1950°C. Tables 1 and 2 show the conditions and measured values.

実施例５
１０Ｂの濃縮度が５０％の１０Ｂ濃縮ホウ酸とした以外は実施例１と同様にした。各条件、測定値を表１、２に示した。 Example 5
The procedure was the same as in Example 1, except that 10 B enriched boric acid with a 10 B enrichment of 50% was used. Tables 1 and 2 show the conditions and measured values.

実施例６
１０Ｂの濃縮度が９９％の１０Ｂ濃縮ホウ酸とした以外は実施例１と同様にした。各条件、測定値を表１、２に示した。 Example 6
Same as Example 1 except that 10 B enriched boric acid with a 10 B enrichment of 99% was used. Tables 1 and 2 show the conditions and measured values.

実施例１～６で得られた六方晶窒化ホウ素粉末は、３５６８ｃｍ－１のＮＨ２基の非対称収縮振動に最高吸収ピークを観測した。また、実施例１～６で作製した六方晶窒化ホウ素粉末は、拡散反射赤外分光測定の８００ｃｍ－１付近の吸収ピーク高さＡと３５３０～３５９０ｃｍ－１の吸収ピーク高さＢとの比Ｂ／Ａが０．０２以上であった。 The hexagonal boron nitride powders obtained in Examples 1-6 observed the highest absorption peak at the asymmetric contraction vibration of the NH 2 group at 3568 cm −1 . Further, the hexagonal boron nitride powders produced in Examples 1 to 6 are the ratio B of the absorption peak height A near 800 cm -1 and the absorption peak height B at 3530 to 3590 cm -1 in diffuse reflectance infrared spectroscopy. /A was 0.02 or more.

比較例１
原料カーボンブラックの硫黄濃度を１００ｐｐｍとした以外は実施例１と同様にした。各条件、測定値を表１、２に示した。比較例１で処理した窒化処理品を蛍光Ｘ線分析測定したところ、窒化処理品の硫黄濃度が１０ｐｐｍであり、実施例１に対して硫黄分の残留分が少ない事が確認された。 Comparative example 1
The procedure was the same as in Example 1, except that the sulfur concentration of the raw carbon black was changed to 100 ppm. Tables 1 and 2 show the conditions and measured values. When the nitriding product treated in Comparative Example 1 was measured by fluorescent X-ray analysis, the sulfur concentration of the nitriding product was 10 ppm, and it was confirmed that the residual sulfur content in the nitriding product was less than in Example 1.

比較例２
比較例２として、３６００～３７５０ｃｍ－１の範囲のＯＨ基、３３５０～３５００ｃｍ－１の範囲のＮＨ２基の対称収縮振動が確認される、日新リフラテック社製Ｒ－ＢＮの各分析測定値を表２に示した。 Comparative example 2
As Comparative Example 2, each analysis measurement value of R-BN manufactured by Nisshin Refratec Co., Ltd., in which symmetric contraction vibration of OH group in the range of 3600 to 3750 cm -1 and NH 2 group in the range of 3350 to 3500 cm -1 is confirmed. Table 2 shows.

比較例１で得られた六方晶窒化ホウ素粉末は明確なピークが観測されず、比較例２の六方晶窒化ホウ素粉末は、３６７０ｃｍ－１のＯＨ基に最高吸収ピークを観測した。 No clear peak was observed in the hexagonal boron nitride powder obtained in Comparative Example 1, and the highest absorption peak was observed in the OH group at 3670 cm −1 in the hexagonal boron nitride powder of Comparative Example 2.

比較例３
１０Ｂを濃縮していないホウ酸を使用した以外は実施例１と同様にした。各条件、測定値を表１、２に示した。 Comparative example 3
Same as Example 1 except that 10 B was used in unconcentrated boric acid. Tables 1 and 2 show the conditions and measured values.

実施例７～１２
実施例１～６で得られた窒化ホウ素粉末をエポキシ樹脂に充填し樹脂組成物を作製し、熱中性子の吸収性能と熱伝導率の評価を行った。エポキシ樹脂は、（三菱化学株式会社製ＪＥＲ８０６）１００質量部と硬化剤（脂環式ポリアミン系硬化剤、三菱化学株式会社製ＪＥＲキュア１１３）２８質量部との混合物を準備した。次に、各基材樹脂４１体積％と、前記特定窒化ホウ素粉末５９体積％とを自転・公転ミキサー（倉敷紡績株式会社製ＭＡＺＥＲＵＳＴＡＲ）にて混合して樹脂組成物を得た。 Examples 7-12
The boron nitride powder obtained in Examples 1 to 6 was filled into an epoxy resin to prepare a resin composition, and thermal neutron absorption performance and thermal conductivity were evaluated. As the epoxy resin, a mixture of 100 parts by mass of JER806 manufactured by Mitsubishi Chemical Corporation and 28 parts by mass of a curing agent (alicyclic polyamine-based curing agent, JER Cure 113 manufactured by Mitsubishi Chemical Corporation) was prepared. Next, 41% by volume of each base resin and 59% by volume of the specific boron nitride powder were mixed in a rotation/revolution mixer (MAZERUSTAR manufactured by Kurashiki Boseki Co., Ltd.) to obtain a resin composition.

これを金型体に注型し、熱プレスを使用し、温度：２００℃、圧力：５ＭＰａ、保持時間：３０分の条件で硬化させ、直径４０ｍｍ、厚さ０．２２ｍｍのシートを作製した。 This was cast into a mold body and cured using a hot press under the conditions of temperature: 200°C, pressure: 5 MPa, holding time: 30 minutes to prepare a sheet with a diameter of 40 mm and a thickness of 0.22 mm.

次いで、以下に示す方法により、本発明の六方晶窒化ホウ素の中性子吸収性能を評価した。 Next, the neutron absorption performance of the hexagonal boron nitride of the present invention was evaluated by the method shown below.

先ず、１０Ｂおよび１０Ｂとともに存在する１１Ｂの中性子捕獲断面積、前記シートに含まれる六方晶窒化ホウ素の分子数および１０Ｂの存在比、前記シートの厚みから、１０Ｂの存在比と熱中性子吸収率の関係を計算によって求め、グラフ化した。得られたグラフを図２に示す。該グラフは、横軸に１０Ｂの存在比、縦軸に熱中性子吸収率の相対値を取ったものである。なお、該相対値とは、熱中性子の吸収が無い場合を０、全ての熱中性子を吸収した場合を１とし算出したものである。該グラフによれば、１０Ｂの存在比が高いほど高い熱中性子吸収性能が得られることがわかる。 First, from the neutron capture cross section of 11 B present together with 10 B and 10 B, the number of molecules of hexagonal boron nitride contained in the sheet and the abundance ratio of 10 B, the thickness of the sheet, the abundance ratio of 10 B and the heat The relationship between the neutron absorption rates was calculated and graphed. The resulting graph is shown in FIG. In the graph, the abscissa indicates the abundance ratio of 10 B and the ordinate indicates the relative value of the thermal neutron absorption rate. The relative value is calculated with 0 when no thermal neutrons are absorbed and 1 when all thermal neutrons are absorbed. According to the graph, it can be seen that the higher the abundance ratio of 10 B, the higher the thermal neutron absorption performance can be obtained.

そして、前記シートの熱中性子吸収性能を評価するため、中性子シンチレータの一種であるＥｕ：ＬｉＣＡＦシンチレータを光検出器に接続して中性子検出器を用意した。まず、前記中性子シンチレータの一面を光出射面とし、当該光出射面以外の面にテープ状のポリテトラフロロエチレンを巻いて光反射膜とした。次いで、光検出器として浜松ホトニクス製：光電子増倍管（Ｒ９８８０Ｕ－１１０）を用意し、当該光電子増倍管の光検出面と前記中性子シンチレータの光出射面を光学グリースによって光学的に接着した後、該中性子シンチレータと光検出器を遮光用の暗幕で覆った。前記光電子増倍管に電源を接続し、また、信号読出し回路として、光電子増倍管側から前置増幅器、整形増幅器及び多重波高分析器を接続し、中性子検出器を得た。 In order to evaluate the thermal neutron absorption performance of the sheet, a neutron detector was prepared by connecting an Eu:LiCAF scintillator, which is a type of neutron scintillator, to a photodetector. First, one surface of the neutron scintillator was used as a light emitting surface, and a tape-like polytetrafluoroethylene was wrapped around the surface other than the light emitting surface to form a light reflecting film. Next, prepare a photomultiplier tube (R9880U-110) manufactured by Hamamatsu Photonics as a photodetector, and optically bond the photodetection surface of the photomultiplier tube and the light emission surface of the neutron scintillator with optical grease. , the neutron scintillator and the photodetector were covered with a blackout curtain. A power supply was connected to the photomultiplier tube, and a preamplifier, shaping amplifier, and multiple pulse height analyzer were connected from the photomultiplier tube side as a signal readout circuit to obtain a neutron detector.

次に、２０ｃｍ角の立方体形状の高密度ポリエチレンの中心にＣｆ－２５２中性子線源を設置し、Ｃｆ－２５２由来の中性子線を高密度ポリエチレンで減速して熱中性子線源とした。 Next, a Cf-252 neutron beam source was placed in the center of a 20 cm square cube-shaped high-density polyethylene, and neutron beams derived from Cf-252 were moderated by the high-density polyethylene to obtain a thermal neutron beam source.

そして、前記シートの熱中性子吸収性能を、中性子カウントの減少率で評価した。まず、中性子検出器と熱中性子線源のみで測定（ブランク測定）を行った。光電子増倍管に接続した電源から高電圧を光電子増倍管に印加し、中性子の入射によって、中性子シンチレータから発せられた光を光電子増倍管でパルス状の電気信号に変換し、当該電気信号を前置増幅器、整形増幅器を介して多重波高分析器に入力した。多重波高分析器に入力された電気信号を解析して波高分布スペクトルを作成した。波高分布スペクトルの中性子由来のピークに正規分布をフィッティングし、その面積から中性子由来のカウント数を求めた。そのときの中性子カウントの減少率を０とした。次に中性子検出器と中性子線源の間に該シートを挿入し、該シート越しに中性子検出を行った。ブランク測定の中性子カウント数とシート越しの測定で得られた中性子カウント数との差分を取り、さらにブランク測定の中性子カウント数で除して中性子カウントの減少率を得た。各シートで得られたカウント減少率を表３に記し、図２のグラフにプロットした。図２によると、該カウント減少率と中性子吸収率とは良い相関を示しており、シート中の１０Ｂの存在比が高いほど、熱中性子吸収性能に優れることがわかる。１０Ｂの存在比が天然のホウ素の１０Ｂの存在比を超える六方晶窒化ホウ素粉末を使用して製作したシートは、１０Ｂの存在比が天然ホウ素の１０Ｂの存在比に相当する六方晶窒化ホウ素粉末を使用して製作したシートより高い熱中性子吸収性能を示した。 Then, the thermal neutron absorption performance of the sheet was evaluated by the neutron count reduction rate. First, measurements (blank measurements) were performed using only the neutron detector and the thermal neutron source. A high voltage is applied to the photomultiplier tube from a power source connected to the photomultiplier tube, and the light emitted from the neutron scintillator due to the incidence of neutrons is converted into a pulsed electrical signal by the photomultiplier tube, and the electrical signal is was input to the multi-pulse height analyzer through a preamplifier and a shaping amplifier. A pulse-height distribution spectrum was created by analyzing the electrical signal input to the multi-pulse-height analyzer. A normal distribution was fitted to the neutron-derived peak in the pulse-height distribution spectrum, and the neutron-derived count was obtained from the area. The decrease rate of the neutron count at that time was set to zero. Next, the sheet was inserted between the neutron detector and the neutron beam source, and neutrons were detected through the sheet. The difference between the neutron count obtained by the blank measurement and the neutron count obtained by the measurement through the sheet was taken and divided by the neutron count obtained by the blank measurement to obtain the neutron count decrease rate. The count reduction rate obtained for each sheet is listed in Table 3 and plotted in the graph of FIG. According to FIG. 2, the count reduction rate and the neutron absorption rate show a good correlation, and it can be seen that the higher the abundance ratio of 10 B in the sheet, the better the thermal neutron absorption performance. The sheet produced using the hexagonal boron nitride powder in which the 10 B abundance ratio exceeds the 10 B abundance ratio of natural boron is a hexagonal It showed higher thermal neutron absorption performance than the sheet fabricated using boron nitride powder.

また、該シートを温度波熱分析装置にて解析し、熱伝導率を算出した結果を表３に示した。実施例１～６で作製した窒化ホウ素粉末を充填したシートの熱伝導率は、７．０Ｗ／ｍ・Ｋ以上であり、高熱伝導率を示した。また、耐電圧試験機（多摩電測株式会社製）にて絶縁耐力を測定した結果を表３に示した。平均４５ｋＶ／ｍｍ以上と高絶縁耐力であった。また、ＪＩＳ Ｃ６４８１に基づき、銅箔と樹脂組成物の銅箔ひきはがし強さを求めた。実施例１で作製した六方晶窒化ホウ素粉末を用いた値を１として、相対値を求めた。 In addition, the sheet was analyzed with a temperature wave thermal analyzer, and the results of calculating the thermal conductivity are shown in Table 3. The thermal conductivity of the sheets filled with the boron nitride powder produced in Examples 1 to 6 was 7.0 W/m·K or higher, indicating high thermal conductivity. In addition, Table 3 shows the results of measuring the dielectric strength with a withstand voltage tester (manufactured by Tama Densoku Co., Ltd.). It had a high dielectric strength of 45 kV/mm or more on average. Moreover, based on JIS C6481, the copper foil peeling strength of the copper foil and the resin composition was determined. A relative value was obtained with the value using the hexagonal boron nitride powder produced in Example 1 as 1.

比較例４～６
比較例１，３で得られた窒化ホウ素粉末及び比較例２の六方晶窒化ホウ素粉末を用いた以外は実施例７～１２と同様にした。該シートの熱中性子の吸収性能を中性子カウントの減少率で評価した。得られた評価結果を表３と図２のグラフに示した。温度波熱分析装置にて該シートを解析し、熱伝導率を算出した結果を表３に示した。また、耐電圧試験機（多摩電測株式会社製）にて絶縁耐力を測定した結果を表３に示した。またＪＩＳ Ｃ６４８１に基づき、銅箔と樹脂組成物の銅箔ひきはがし強さを求め、実施例１で作製した六方晶窒化ホウ素粉末を用いた値を１として、相対値を求めた。比較例１で得られた窒化ホウ素粉末及び比較例２の市販品六方晶窒化ホウ素粉末を充填したシートはいずれも７．０Ｗ／ｍ・Ｋ、４５ｋＶ／ｍｍ以下であり、低熱伝導率、低絶縁耐力を示した。また、銅箔ひきはがし強さは実施例１の値を１としたときに、０．５以下であり、接着強度が弱かった。
Comparative Examples 4-6
The procedure was the same as in Examples 7 to 12, except that the boron nitride powders obtained in Comparative Examples 1 and 3 and the hexagonal boron nitride powder of Comparative Example 2 were used. The thermal neutron absorption performance of the sheet was evaluated by the reduction rate of the neutron count. The obtained evaluation results are shown in Table 3 and the graph of FIG. The sheet was analyzed with a temperature wave thermal analyzer, and the results of calculating the thermal conductivity are shown in Table 3. In addition, Table 3 shows the results of measuring the dielectric strength with a withstand voltage tester (manufactured by Tama Densoku Co., Ltd.). Also, based on JIS C6481, the copper foil peeling strength of the copper foil and the resin composition was determined, and relative values were determined by setting the value using the hexagonal boron nitride powder produced in Example 1 to 1. The sheets filled with the boron nitride powder obtained in Comparative Example 1 and the commercially available hexagonal boron nitride powder in Comparative Example 2 are both 7.0 W / m K and 45 kV / mm or less, and have low thermal conductivity and low insulation. showed endurance. Moreover, the copper foil peeling strength was 0.5 or less when the value of Example 1 was taken as 1, and the adhesive strength was weak.

Figure 0007138481000001
Figure 0007138481000001

Figure 0007138481000002
Figure 0007138481000002

Figure 0007138481000003
Figure 0007138481000003

Claims (9)

全ホウ素中の１０Ｂの存在比が５０％以上であり、拡散反射赤外分光スペクトルの３１００～３８００ｃｍ－１の範囲における最高吸収ピークが３５３０～３５９０ｃｍ－１の範囲にあり、酸素濃度が０．２１質量％以下である六方晶窒化ホウ素粉末。 The abundance ratio of 10 B in all boron is 50% or more, the highest absorption peak in the range of 3100 to 3800 cm -1 of the diffuse reflectance infrared spectrum is in the range of 3530 to 3590 cm -1 , and the oxygen concentration is 0 .21% by weight or less of a hexagonal boron nitride powder. 拡散反射赤外分光スペクトルの８００ｃｍ－１付近の窒化ホウ素に由来する吸収ピークの高さＡと、３５３０～３５９０ｃｍ－１の範囲における最高吸収ピークの高さＢの比（Ｂ／Ａ）が０．０２以上である請求項１に記載の六方晶窒化ホウ素粉末。 The ratio (B/A) of the height A of the absorption peak derived from boron nitride in the vicinity of 800 cm −1 in the diffuse reflectance infrared spectrum and the height B of the highest absorption peak in the range of 3530 to 3590 cm −1 is 0. 02 or more, the hexagonal boron nitride powder according to claim 1. 比表面積が１５ｍ２／ｇ以下である請求項１又は２に記載の六方晶窒化ホウ素粉末。 The hexagonal boron nitride powder according to claim 1 or 2, having a specific surface area of 15 m 2 /g or less. 請求項１～３のいずれか一項に記載の六方晶窒化ホウ素粉末を含む中性子吸収用組成物。 A neutron absorbing composition comprising the hexagonal boron nitride powder according to any one of claims 1 to 3 . 請求項４に記載の中性子吸収用組成物を含む樹脂組成物。 A resin composition comprising the neutron absorbing composition according to claim 4 . 請求項４に記載の中性子吸収用組成物と、酸化アルミニウム粉末及び／又は窒化アルミニウム粉末を含む混合粉末を充填してなる樹脂組成物。 A resin composition filled with a mixed powder containing the neutron absorbing composition according to claim 4 and aluminum oxide powder and/or aluminum nitride powder. 請求項５又は６に記載の樹脂組成物よりなる放熱絶縁シート。 A heat-dissipating insulating sheet comprising the resin composition according to claim 5 or 6 . 請求項７に記載の放熱絶縁シートよりなる電子部品の放熱絶縁部材。 A heat-dissipating insulating member for an electronic component, comprising the heat-dissipating insulating sheet according to claim 7 . 全ホウ素中の１０Ｂの濃縮度が５０％以上である１０Ｂ濃縮含酸素ホウ素化合物、カーボン源、含酸素カルシウム化合物を、１０Ｂ濃縮含酸素ホウ素化合物に含まれるＢ源とカーボン源に含まれるＣ源の割合であるＢ／Ｃ（元素比）換算で０．７５～０．８５、１０Ｂ濃縮含酸素ホウ素化合物とカーボン源との合計量（Ｂ２Ｏ３、Ｃ換算値）１００質量部に対して含酸素カルシウム化合物をＣａＯ換算で１０～１５質量部となる割合で混合し、該混合物を窒素雰囲気下にて、１４５０～１５５０℃で４時間以上、１６５０～２１００℃で２時間以上加熱して、還元窒化した後、反応生成物中に存在する窒化ホウ素以外の副生成物を酸洗浄により除去することを特徴とする六方晶窒化ホウ素粉末の製造方法において、該カーボン源の硫黄濃度が１０００～１００００ｐｐｍの範囲であることを特徴とする、六方晶窒化ホウ素粉末の製造方法。 A 10 B-enriched oxygenated boron compound, a carbon source, and an oxygenated calcium compound having a concentration of 10 B in total boron of 50% or more are included in the B source and the carbon source contained in the 10 B-enriched oxygenated boron compound. 0.75 to 0.85 in terms of B/C (element ratio), which is the ratio of the C source, and the total amount of the 10 B-enriched oxygenated boron compound and the carbon source (B 2 O 3 , C conversion value) 100 parts by mass 10 to 15 parts by mass in terms of CaO is mixed with the oxygen-containing calcium compound, and the mixture is heated at 1450 to 1550 ° C. for 4 hours or more and at 1650 to 2100 ° C. for 2 hours or more in a nitrogen atmosphere. and after reducing and nitriding, by-products other than boron nitride present in the reaction product are removed by acid washing, wherein the sulfur concentration of the carbon source is A method for producing hexagonal boron nitride powder, characterized in that the concentration is in the range of 1000 to 10000 ppm.
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