JP2004296875A - Process for producing flexible hybrid rare earth bonded magnet, magnet and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material exhibiting (BH)max higher than that of a magnetically isotropic bonded magnet by fixing an Nd<SB>2</SB>Fe<SB>14</SB>B based aggregated polycrystalline rare earth magnet powder of pulverized melt span ribbon with resin. <P>SOLUTION: A compound precursor forming a cell of single domain particle rare earth magnet powder through a medium of binder component using a magnetically anisotropic aggregated polycrystalline rare earth magnet powder as a core substance is prepared, and a compound comprising the precursor, a powdery thermosetting polymer compound and the binder is compacted while applying an orienting magnetic field in the plasticizing temperature region of the powdery thermosetting polymer compound. A green compact can be made while suppressing mutual mechanical damage of the core substance of compound precursor, i.e. the aggregated polycrystalline rare earth magnet powder, by the compression stress distributing action of the precursor cell or the buffering action of the powdery thermosetting polymer compound through plastic deformation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３３】
（ＮＨ_２ＮＨＣＯＣＨ_２ＣＨ_２）_２Ｎ（ＣＨ_２）_１１ＣＯＮＨＮＨ_２・・（化２）
【００３４】
（実施例の説明２、コンパウンド前駆体の作製）
先ず、本発明にかかるコンパウンド前駆体の芯物質となるＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型異方性希土類磁石粉末１は、予め液状エポキシオリゴマ−（０．５、または１．０ｗｔ．％）で図４（ａ）に示したように表面被覆した。ただし、図４（ａ）において、１は多結晶集合型希土類磁石粉体、３は表面被覆したエポキシオリゴマ−である。なお、エポキシオリゴマ−３はケトン系有機溶媒（アセトン）にて希釈し、当該有機溶媒溶液を多結晶集合型希土類磁石粉体１表面に存在し得る図９の矢印で示すマイクロクラックにも浸透させるようにした。
【００３５】
次いで、図４（ｂ）に示した如く、コンパウンド前駆体の芯物質Ｎｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体１表面のエポキシオリゴマ−３をセル形成媒体とし、図３で示したような本発明にかかるＳｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体２を（０〜４０ｗｔ．％）セル物質として付着せしめた。斯様に、比較的簡単なプロセスによって、本発明でいう多結晶集合型希土類磁石粉体を芯物質とし、結合剤成分の媒体を介して単磁区粒子型希土類磁石粉体でセルを形成する構成のコンパウンド前駆体Ａを作製することができる。ここではさらに、図４（ｂ）のコンパウンド前駆体Ａのセル部分に図４（ｃ）のような結合剤構成成分４（粉体状潜在性エポキシ効果剤）を０．３ｗｔ．％付着せしめた。
【００３６】
（実施例の説明３、グリ−ンコンパクトの作製）
以上のようなコンパウンド前駆体Ａは図６のように、熱可塑性高分子化合物粉体５（ここではペンタエリスリト−ルＣ１７トリエステル１０重量部を含む、ポリアミド粉体３ｗｔ．％）と混合して本発明にかかるコンパウンドＢに仕上げた。
【００３７】
上記、本発明にかかるコンパウンドＢを粉体状熱可塑性高分子化合物５の可塑化温度領域（８０℃）に加熱した成形型キャビティに充填すると、当該コンパウンドは温度上昇し、図６（ａ）のように粉体状熱可塑性高分子化合物５は軟化し、且つコンパウンド前駆体Ａと互いに接触するようになる。他方では、セル形成媒体のエポキシオリゴマ−３も低粘度化し、セルの単磁区粒子型希土類磁石粉体２への拘束力が減少する。このような状態で配向磁界Ｈ（２ＭＡ／ｍ）を印加するとコンパウンド前駆体Ａのコアである多結晶集合型希土類磁石粉体１、セルである単磁区粒子型希土類磁石粉体２各々の磁化容易軸１１（００６）、２２（００６）は何れも配向磁界Ｈの印加方向に磁化され、図６（ｂ）のように配向する。
【００３８】
上記のように、配向磁界を印加したのち、配向磁界を印加した状態で圧縮圧力を加える。すると、コンパウンドＢ全体の緻密化が始まる。その際、多結晶集合型希土類磁石粉体１はセル形成媒体３と単磁区粒子型希土類磁石粉体２、および粉体状熱可塑性高分子化合物５の緩衝作用によって互いに直接的に殆ど接触することなく図７（ａ）のように緻密化が進行する。その際、図７（ａ）２Ａのように、単磁区粒子型希土類磁石粉体２の一部は粉体状熱可塑性高分子化合物５に取り込まれるように緻密化し、他方では、図７（ａ）２Ｂのように多結晶集合型希土類磁石粉体１の間に介在して多結晶集合型希土類磁石粉体１に生じる圧縮応力を分散せしめる。また、粉体状熱可塑性高分子化合物は図７（ａ）５Ａのように多結晶集合型希土類磁石粉体１間で形成された比較的大きな空間に塑性変形しながら移動する場合もある。そして、圧縮圧力が最大（０．６〜１．０ ＧＰａ）に達すると緻密化は終息する。その際、図７（ｂ）のように、多結晶集合型希土類磁石粉体１の境界部（Ｂｏｕｎｄａｒｙ）は単磁区粒子型希土類磁石粉体２、エポキシオリゴマ−のような結合剤成分３、潜在性エポキシ硬化剤のような結合剤成分４、粉体状熱可塑性高分子化合物５が殆ど空隙なく複合化した状態となる。
【００３９】
上記、図７（ｂ）を成形型キャビティから取り出せば、本発明にかかるグリ−ンコンパクトが得られるのである。
【００４０】
（実施例の説明４、ハイブリッド型希土類ボンド磁石の作製）
以上のように作製したグ−ンコンパクトを加熱（１８０℃、１５ｍｉｎ）すると、図８（ａ）のようにエポキシオリゴマ−のような結合剤成分３、潜在性エポキシ硬化剤のような結合剤成分４、粉体状熱可塑性高分子化合物５が互いに架橋した連続相６で多結晶集合型希土類磁石粉体１および単磁区粒子型希土類磁石粉体２を所定形状に固定化した構成の本発明にかかるハイブリッド型希土類ボンド磁石が得られる。なお、当該ハイブリッド型希土類ボンド磁石を塑性加工することにより円弧状、或いは環状に形状変換することができる。円弧状とするには図８（ａ）の当該磁石をホットスタンパブル（温間成形型を用いた塑性加工）でシ−ト状から円弧状に形状変換する。或いは、所望の環状とするには、当該磁石の連続相６を図８（ｂ）６６のように一方向に延伸する。このように結合剤を延伸した本発明にかかるハイブリッド型希土類ボンド磁石はシ−ト状から巻きつけることによって環状に形状変換できる。なお、延伸率を１０％以下とした厚さ１．１ｍｍ以下のシ−ト状から環状に形状変換すると、多結晶集合型希土類磁石粉体１および単磁区粒子型希土類磁石粉体２の延伸による配向の減少を抑制することができる。
【００４１】
（実施例の説明５、高（ＢＨ）ｍａｘ化に関するハイブリッド効果）
図１０は本発明にかかる異方性ハイブリッド型希土類ボンド磁石の（ＢＨ）ｍａｘをコンパウンド前駆体Ａの芯物質であるＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体１に対して、セルであるＳｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体２の割合（ｗｔ．％）をプロットした特性図である。また、図中に示した比較例は、Ｓｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体２をエポキシオリゴマ−３（０．５ ｗｔ．％）を用いて３５０μｍ以下に予めグラニュ−ル化したものを多結晶集合型希土類磁石粉体１、並びに粉体状熱可塑性高分子化合物５と混合したコンパウンドを作製し、同一成形条件で磁石としたものである。なお、磁石の寸法は８ｍｍ×８ｍｍ×８ｍｍの立法体をＰｃ≒３に加工し、配向した方向に４ＭＡ／ｍのバルス磁界で磁化したのちに測定磁界Ｈｍ±１．６ＭＡ／ｍの下、ＶＳＭで測定したものである。
【００４２】
図１０から明らかなように、比較例のようにコンパウンドにグラニュ−ル化したＳｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体が存在すると、当該グラニュ−ルは圧縮の際に系内で分散されない。したがって、Ｎｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体粒子１の間にはグラニュ−ル化したＳｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体を多量に含ませることはできない。しかしながら、本発明にかかるコンパウンド前駆体Ａから構成したコンパウンドＢを用いると、セル形成媒体の量にもよるが、単磁区粒子型希土類磁石粉体が系内でよく分散しているため、比較例よりも多くの量を含有させても（ＢＨ）ｍａｘは減少しない。むしろ、図１０から明らかなように、本発明例１（０．５ｗｔ．％），２（１．０ｗｔ．％）のハイブリッド型希土類ボンド磁石では単磁区粒子型希土類磁石粉体の割合が概ね５ｗｔ％から２０ｗｔ．％、または３０ｗｔ．％の範囲で（ＢＨ）ｍａｘは１６０ｋＪ／ｍ^３を越える程に改善さけるのである。また、結合剤含有量２〜３ｗｔ％の範囲では、圧縮圧力０．６〜１．０ＧＰａの範囲で（ＢＨ）ｍａｘの水準に差はなく、両者共に１６０ｋＪ／ｍ^３を越える（ＢＨ）ｍａｘ値が得られる。この（ＢＨ）ｍａｘの水準は、ＴｏｋｕｎａｇａらのＮｄ_１４Ｆｅ_８０−ＸＢ_６Ｇａ_Ｘ（Ｘ＝０．４〜０．５）を熱間据え込み加工（Ｄｉｅ−ｕｐ−ｓｅｔ）して得たバルクを機械粉砕した保磁力ＨｃＪ＝１．５２ＭＡ／ｍの異方性Ｎｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体を樹脂で固めた（ＢＨ）ｍａｘ＝１２７ｋＪ／ｍ^３の異方性希土類ボンド磁石［Ｍ．Ｔｏｋｕｎａｇａ，Ｎ．Ｎｏｚａｗａ，Ｋ．Ｉｗａｓａｋｉ，Ｍ．Ｅｎｄｏｈ，Ｓ，Ｔａｎｉｇａｗａ ａｎｄ Ｈ．Ｈａｒａｄａ：ＩＥＥＥ Ｔｒａｎｓ．Ｍａｇｎ．，Ｖｏｌ．２５，３５６１（１９８９）］。或いは、Ｍ．Ｄｏｓｅｒ，Ｖ．Ｐａｎｃｈａｎａｔｈａｎらの、熱間加工後のバルクの粒界から水素を侵入させＮｄ_２Ｆｅ_１４ＢＨ_Ｘとして崩壊させ、その後真空加熱により脱水素したＨＤ（Ｈｙｄｒｏｇｅｎ Ｄｅｃｒｅｐｉｔａｔｉｏｎ）異方性Ｎｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体を樹脂で固めた（ＢＨ）ｍａｘ＝１５０ｋＪ／ｍ^３の希土類ボンド磁石［Ｍ．Ｄｏｓｅｒ，Ｖ．Ｐａｎｃｈａｎａｃｔｈａｎ，ａｎｄ Ｒ．Ｋ．Ｍｉｓｈｒａ：Ｊ．Ａｐｐｌ．Ｐｈｙｓ．，Ｖｏｌ．７０，６６０３（１９９１）］に比較しても、本発明にかかるハイブリッド型希土類ボンド磁石の（ＢＨ）ｍａｘはコンパウンド前駆体Ａの構造によるハイブリッド効果によって明らかに上回るものとなっている。
【００４３】
（実施例の説明６、初期不可逆磁束損失低減に関するハイブリッド効果）
図１１は実施例の説明５で示した本発明例１（Ｓｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体１０ｗｔ．％）と同じ磁石を４ＭＡ／ｍのパルス磁界で磁化したのち、１００℃および１２０℃の空気中に各１時間暴露し、暴露前後の磁束量をサ−チコイル引抜法で測定し、初期不可逆減磁を算出し、単磁区粒子型希土類磁石粉体の含有量に対してプロットした特性図である。図から明らかなように暴露温度に拘らず単磁区粒子型希土類磁石粉体量が増すと初期不可逆減磁が減少する。とくに、４０ｗｔ．％付近になると多結晶集合型希土類磁石粉体のみの異方性希土類ボンド磁石に比べ、略１／２〜１／３も初期不可逆磁束損失が減少する。すなわち、本発明にかかるハイブリッド型希土類ボンド磁石はコンパウンド前駆体Ａにより、単磁区粒子型希土類磁石粉体を均質に分散した状態で多量に含ませることができるので、高水準の（ＢＨ）ｍａｘを確保しながら、同時に初期不可逆磁束損失を低減することができるハイブリッド効果が認められる。
【００４４】
（実施例の説明７、長期不可逆磁束損失低減に関するハイブリッド効果）
図１２は実施例の説明５で示した本発明例１（Ｓｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体１０ｗｔ．％）と同じ磁石を４ＭＡ／ｍのパルス磁界で磁化したのち、１００℃の空気中に１０００時間暴露し、任意時間毎に暴露前後の磁束量をサ−チコイル引抜法で測定し、不可逆磁束損失の経時変化を示した特性図である。ただし、図中の比較例２は３ｗｔ．％の室温で液状のエポキシ樹脂を結合剤とした従来の異方性希土類ボンド磁石の結果を示している。また、比較例２の磁石で使用した多結晶集合型希土類磁石粉体は本発明例で使用した平均粒子径８０μｍのＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体（Ｎｄ_１２．３Ｄｙ_０．３Ｆｅ_６４．７Ｃｏ_１２．３Ｂ_６．０Ｇａ_０．６Ｚｒ_０．１）と同じものである。図から明らかなように、本発明にかかるハイブリッド型希土類ボンド磁石は長期不可逆磁束損失も減少する。とくに、１０００時間高温暴露後に４ＭＡ／ｍで再着磁した本発明例１のハイブリッド型希土類ボンド磁石の永久磁束損失は３．３％ほどであり、比較例２の６．５％に比べて約１／２も減少する。すなわち、本発明にかかるハイブリッド型希土類ボンド磁石はコンパウンド前駆体Ａの構造により、単磁区粒子型希土類磁石粉体を均質に多量に含ませることができるので、高（ＢＨ）ｍａｘ化、初期不可逆磁束損失ばかりか、長期不可逆磁束損失や希土類磁石粉体の組織変化に基づく永久磁束損失を低減することができるのである。
【００４５】
（実施例の説明８、ハイブリッド組織の観察）
図１３（ａ）は実施例の説明５で示した本発明例１（Ｓｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体１０ｗｔ．％）と同じ磁石の破断面の状態を示す特性図である。また、図１３（ｂ）は実施例の説明７で示した比較例２（は３ｗｔ．％の室温で液状のエポキシ樹脂を結合剤とした従来の異方性希土類ボンド磁石）の破断面を示す特性図である。ただし、両者共に走査方電子顕微鏡による観察結果を示している。図１３（ａ）（ｂ）を比較すると（ｂ）ではＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体にマイクロクラックが生じていること、磁石粉体自体が破砕されている状況が確認される。これは磁石成形時の圧縮応力（０．８ＧＰａ）に抗しきれなかったために生じたものである。他方、本発明にかかる図１３（ａ）では図１３（ｂ）のようにＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体のマイクロクラック、磁石粉体の破砕状況は判り難い。この原因はコンパウンド前駆体セルを形成していたＳｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体が粉体状熱可塑性高分子化合物とともにＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体の損壊を抑制したためであり、引いては実施例の説明５の高（ＢＨ）ｍａｘ化、更には実施例の説明６及び実施例の説明７で説明した磁束損失の減少を招いたものと結論付けることができる。
【００４６】
（実施例の説明６、塑性加工による賦形とモ−タの基本性能）
本発明例１（Ｓｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体１０ｗｔ．％）と同じ条件で本発明にかかる（ＢＨ）ｍａｘ＝１６２ｋＪ／ｍ^３、厚さ０．９７ｍｍの板状ハイブリッド型希土類ボンド磁石を作製した。続いて、前記板状ハイブリッド型希土類ボンド磁石をスタンピング加工によって内半径３．５５ｍｍ、外半径３．６５ｍｍ、最大肉厚０．８８ｍｍ、長さ１０ｍｍの薄肉円弧状磁石とした。ただし、当該塑性加工条件は温度１２０℃、圧力０．５ＧＰａ、圧力保持時間０．１ｓｅｃである。このような条件で最終形状に賦形された本発明にかかる薄肉円弧状磁石は亀裂発生することなく、所望の寸法精度が確保されていた。一方、比較例３として、メルトスパンリボンを粉砕した磁気的に等方性のＮｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体（Ｎｄ_１２Ｆｅ_７７Ｃｏ_５Ｂ_６）をエポキシ樹脂とともに内半径３．５５ｍｍ、外半径３．６５ｍｍ、最大肉厚０．８８ｍｍ、長さ１０ｍｍの薄肉円弧状に圧縮成形したボンド磁石を作製した。なお、この磁石の４ＭＡ／ｍバルス着磁後の（ＢＨ）ｍａｘは７２ｋＪ／ｍ^３であった。
【００４７】
上記２種類の円弧状磁石を４ＭＡ／ｍでパルス着磁したとき、両者の磁束を比較すると本発明にかかる磁石は等方性Ｎｄ_２Ｆｅ_１４Ｂ系圧縮成形ボンド磁石の１．５３倍であった。次いで、前記２種類の薄肉円弧状希土類ボンド磁石を外径１６ｍｍ、軸方向長さ１９ｍｍの小型直流モ−タの永久磁石界磁とし、そのトルク定数Ｋｔを求めた。その結果、本発明にかかる磁石を界磁とした直流モ−タのＫｔは０．００１６ｍＮ・ｍ／ｍＡを示し、等方性Ｎｄ_２Ｆｅ_１４Ｂ系圧縮成形ボンド磁石を界磁とした直流モ−タのＫｔに対して１．４５倍であった。
一方、本発明例１（Ｓｍ_２Ｆｅ_１７Ｎ_３系単磁区粒子型希土類磁石粉体１０ｗｔ．％）と同じ条件で本発明にかかる（ＢＨ）ｍａｘ＝１６２ｋＪ／ｍ^３、厚さ０．９７ｍｍの板状ハイブリッド型希土類ボンド磁石を作製した。続いて、前記板状希土類ボンド磁石を図１４のような温間圧延で厚さ０．９３ｍｍに延伸した。このように、延伸した磁石の破断面を図１５に示す。なお、当該磁石の延伸前は図１３（ａ）に相当する。図１３（ａ）と図１４によって磁石の延伸前後の破断面を比較すると、均質に延伸されている様子が伺える。
【００４８】
当該磁石は圧延方向に可撓性が発現する。そのため、任意の直径を持つ環状形状に賦形することができる。当該磁石は環状に賦形したとき、言うまでもなく半径方向に１６０ｋＪ／ｍ^３級の（ＢＨ）ｍａｘを有する所謂ラジアル異方性希土類ボンド磁石に他ならない。したがって、実質的に〜８０ｋＪ／ｍ^３級の（ＢＨ）ｍａｘである等方性Ｎｄ_２Ｆｅ_１４Ｂ系圧縮成形ボンド磁石を界磁とした直流モ−タのＫｔに対して１．４３倍が得られた。ところで、モ−タの効率ηは機械出力Ｐ、損失をＷとすると下式で表すことができる。
【００４９】
η＝［Ｐ／（Ｐ＋Ｗ）］・・・（式３）
したがって、等方性Ｎｄ_２Ｆｅ_１４Ｂ系圧縮成形ボンド磁石を界磁とした代表的な小型直流モ−タに対して、本発明の目的のひとつである高出力化によるモ−タの高効率化が実現できると結論づけることができる。
【００５０】
【発明の効果】
小型モ−タのための多様な磁石形状に対応する高（ＢＨ）ｍａｘハイブリッド型希土類ボンド磁石を提供するため、本発明は、磁気的に異方性の多結晶集合型希土類磁石粉体を芯物質として結合剤成分の媒体を介して単磁区粒子型希土類磁石粉体でセルを有するコンパウンド前駆体を準備し、少なくとも当該前駆体と粉体状熱可塑性高分子化合物、結合剤成分とで構成した本発明にかかるコンパウンドを、前記粉体状熱可塑性高分子化合物の可塑化温度領域で配向磁界を印加しながら緻密化する。すると、当該前駆体のセルによる圧縮応力の分散作用や当該粉体状熱可塑性高分子化合物の塑性変形による緩衝作用によってコンパウンド前駆体の芯物質である多結晶集合型希土類磁石粉体相互の機械的損壊を抑制しながら緻密化したグリ−ンコンパクトを作製することができる。然る後、得られた当該グリ−ンコンパクトを加熱し、当該結合剤構成成分を架橋せしめて連続相を形成すると本発明にかかるハイブリッド型希土類ボンド磁石が得られる。さらに、（ＢＨ）ｍａｘを維持して多様な小型モ−タの磁石形状に対応するために当該磁石を塑性加工で形状変換する技術が本発明の骨子となる。その結果、異方性Ｎｄ_２Ｆｅ_１４Ｂ系多結晶集合型希土類磁石粉体を用いて小口径化、或いは薄肉化しても磁石の（ＢＨ）ｍａｘが減少しないばかりか、不可逆磁束損失に代表得される耐久性を改善することができる。
【００５１】
例えば、小型モ−タに適用し得る任意の環状、或いは円弧状で、例えば、１６０ｋＪ／ｍ^３以上の高（ＢＨ）ｍａｘ希土類ボンド磁石が、その磁石の大きさに拘らず容易に作製できるので、高出力、高効率の小型モ−タを提供することができ、電気電子機器類の高性能化を促す。何故なら、従来のメルトスパンリボンを粉砕したＮｄ_２Ｆｅ_１４Ｂ系希土類磁石粉体を樹脂で固定した等方性希土類ボンド磁石の（ＢＨ）ｍａｘは略８０ｋＪ／ｍ^３である。これに対し、任意の環状、或いは円弧状で１６０ｋＪ／ｍ^３以上の高（ＢＨ）ｍａｘ希土類ボンド磁石が作製できるからである。
【００５２】
モ−タ磁石と鉄心との空隙磁束密度は略（ＢＨ）ｍａｘの比の平方根となるから、当該小型モ−タの設計思想によるが、約１．４倍の高出力化、３０％の小型化、軽量化などが見込まれるのである。
【００５３】
以上のように、本発明が対象とするコンピュ−タ周辺機、プリンタなどの電気電子機器類の制御用、駆動用として幅広く使用され、所謂永久磁石回転子型、或は永久磁石界磁型のブラシレスモ−タや直流モ−タに関して、当該機器類の高性能化のもと、小型モ−タの更なる小型軽量化、高出力化に対する要求に応えることができる。
【図面の簡単な説明】
【図１】ラジアル配向磁界成形型の構成図
【図２】異方性多結晶集合型希土類磁石粉体の概念図
【図３】異方性単磁区粒子型希土類磁石粉体の概念図
【図４】（ａ）コンパウンド前駆体の構成状態ａを示す概念図
（ｂ）コンパウンド前駆体の構成状態ｂを示す概念図
（ｃ）コンパウンド前駆体の構成状態ｃを示す概念図
【図５】コンパウンド前駆体を含むコンパウンドの概念図
【図６】（ａ）キャビティへの充填と配向状態ａを示す概念図
（ｂ）キャビティへの充填と配向状態ｂを示す概念図
【図７】（ａ）コンパウンドの緻密化の状態ａを示す概念図
（ｂ）コンパウンドの緻密化の状態ｂを示す概念図
【図８】（ａ）延伸前の結合剤の分子配向を示す概念図
（ｂ）延伸後の結合剤の分子配向を示す概念図
【図９】多結晶集合型希土類磁石粉体のマイクロクラックを示す特性図
【図１０】異方性ハイブリッド型希土類ボンド磁石の（ＢＨ）ｍａｘを示す特性図
【図１１】異方性ハイブリッド型希土類ボンド磁石の初期不可逆磁束損失を示す特性図
【図１２】異方性ハイブリッド型希土類ボンド磁石の長期不可逆磁束損失を示す特性図
【図１３】異方性ハイブリッド型希土類ボンド磁石の破断面組織を示す特性図
【図１４】延伸した異方性ハイブリッド型希土類ボンド磁石の破断面組織を示す特性図
【符号の説明】
Ａ コンパウンド前駆体
１ 多結晶集合型希土類磁石粉体（芯物質）
２ 単磁区粒子型希土類磁石粉体（セル形成物質）
３ セル形成媒体となる結合剤構成成分
４ 架橋のための結合剤構成成分[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is widely used for controlling and driving electric and electronic devices such as computer peripherals, printers, etc., and a so-called permanent magnet rotor type in which technological innovation is active mainly in downsizing, weight reduction and high output, Also, the present invention relates to a permanent magnet field type brushless motor or a direct current motor, and more particularly to a method of manufacturing an annular or arc-shaped hybrid rare earth bonded magnet mounted thereon.
[0002]
[Prior art]
Non-Patent Document 1: J. J. J. Croat, J. et al. F. Herbst, R .; W. Leeand F. E. FIG. Pinkerton: J. Appl. Phys. , Vol. According to 55, 2078 (1984), a ribbon obtained by melt-spreading an R-Fe-B (R is Nd, Pr) alloy has Hci> 1200 kA / m, residual magnetization (Mr) 800 mT, and maximum energy product (BH) max 112 kJ / m. ³ It was revealed that. At the same time, Non-Patent Document 2: Sagawa, S .; Fujiwara, H .; Yamamoto and Y. Matsuura et al. Appl. Phys. , Vol. 55, 2083 (1984), (BH) max 304 kJ / m by powder metallurgy using an Nd-Fe-B alloy as a starting material. ³ It was clarified that the sintered magnet of No. could be obtained. In 1986, Non-Patent Document 3: J. F. Herbst, R .; W. Lee and F.S. E. FIG. Pinkerton et al., Ann. Rev .. Mater. Sci. , Vol. 16, 467 (1986). J. Croat et al. The main phase of the Nd-Fe-B ternary alloy of Sagawa et al. Is Nd ₂ Fe ₁₄ It was revealed that it was a B intermetallic compound. This Nd ₂ Fe ₁₄ As a method for producing a B-based rare earth magnet, a mechanical alloying method, a hot casting method, and the like have been proposed. However, from the late 1980's to the present, a new market was created and expanded. ₂ Fe ₁₄ B-based rare earth magnets are available from Nd by powder metallurgy technique of Sagawa et al. ₂ Fe ₁₄ A B-based rare earth sintered magnet; J. Nd starting from the melt spun ribbon of Croat et al. ₂ Fe ₁₄ It is classified into two systems of B-based rare earth bonded magnets.
[0003]
First, Nd by powder metallurgy ₂ Fe ₁₄ Although it is a B-based rare earth sintered magnet, the production of this magnet has an advantage that a method of producing a 1-5, 2-17 type Sm-Co-based sintered magnet which has already been produced on an industrial scale can be used. Production technology on an industrial scale was quickly established, and (BH) max 300 kJ / m ³ As the strongest magnets described above, MRI, VCM, FA motors and EV motors have become widespread for relatively large motors having a mechanical output of several hundred W to several tens of kW.
[0004]
On the other hand, J. The material form obtained by the melt span of Croat et al. Is limited to a ribbon such as a ribbon or a flake-like powder obtained by grinding the ribbon. For this reason, in order to obtain a generally used bulk permanent magnet, a technique of changing the material form, that is, a technique of fixing a ribbon or powder to a specific bulk by some method is required. The basic powder fixing means in powder metallurgy is pressureless sintering, but it is difficult to apply pressureless sintering because melt spun ribbons need to maintain magnetic properties based on a metastable state. Therefore, it has been practiced to fix the ribbon or powder to a bulk having a specific shape exclusively with a binder such as an epoxy resin. Non-Patent Document 4: R.A. W. Lee, E.A. G. FIG. Brewer and N.M. A. Shaffel: IEEE Trans. Magn. , Vol. 21, 1958 (1985), (BH) _max 111kJ / m ³ When melt spun ribbon is fixed with resin (BH) _max 72kJ / m ³ It is said that the isotropic rare earth bonded magnet of the above was made.
[0005]
In 1986, the present inventors found that the melt spun ribbon was pulverized with Nd ₂ Fe ₁₄ B-based rare earth magnet powder solidified with resin (BH)) max ~ 72 kJ / m ³ It has been found that a small-diameter annular isotropic rare-earth bonded magnet having a diameter of 25 mm or less is useful for a small motor, and the characteristics of the small motor are described in Patent Document 1: Japanese Patent Application Laid-Open No. Sho 62-196957. No. 61-38830). Thereafter, the small motor characteristics of the small-diameter annular isotropic bonded magnet and the Sm-Co-based radial anisotropic bonded magnet are compared, and it is verified that the former is useful (Non-Patent Document 5: T. Shimoda). , SUPPLEMENTARY MATERIAL, "PERMANENT MAGNETS 1988 UPDATE" Wheeler Associate, INC (1988)). Further, a report that it is useful for a small motor is disclosed in Non-Patent Document 6: W.M. Baran, The European Business and Technical Outlook for NdFeB Magnets "Nov. (1989), Non-Patent Document 7: GX Huang, W. M. Gao, SF. -B Bonded Magnet to the Micro-motor ", Proc. Of the 11 ^th International Rare-Earth Magnets and Their Applications, Pittsburgh, USA, pp. 583-595, (1990). Therefore, since the 1990's, Nd obtained by pulverizing a melt spun ribbon as a drive source of electrical and electronic equipment such as OA, AV, PC and its peripheral equipment, information communication equipment, etc. ₂ Fe ₁₄ B-based rare earth magnet powder solidified with resin (BH)) max ~ 72 kJ / m ³ It has been widely used in various small high-performance motors using a small-diameter annular isotropic rare earth bonded magnet having a diameter of 25 mm or less.
[0006]
Hereinafter, patent documents and non-patent documents described in the description of the related art will be described. Patent documents and non-patent documents cited in the problem to be solved by the invention are described.
[0007]
[Patent Document 1]
JP-A-62-196057 (Japanese Patent Application No. 61-38830)
[Patent Document 2]
JP-A-57-170501
[Non-patent document 1]
J. J. Croat, J. et al. F. Herbst, R .; W. Lee and F.S. E. FIG. Pinkerton: J. Appl. Phys. , Vol. 55, 2078 (1984)
[Non-patent document 2]
M. Sagawa, S .; Fujiwara, H .; Yamamoto and Y. Matsuura et al. Appl. Phys. , Vol. 55, 2083 (1984)
[Non-Patent Document 3]
J. F. Herbst, R .; W. Lee and F.S. E. FIG. Pinkerton et al., Ann. Rev .. Mater. Sci. , Vol. 16,467 (1986)
[Non-patent document 4]
R. W. Lee, E.A. G. FIG. Brewer and N.M. A. Shaffel: IEEE Trans. Magn. , Vol. 21, 1958 (1985)
[Non-Patent Document 5]
T. Shimoda, SUPPLEMENTARY MATERIAL, "PERMANENT MAGNETS 1988 UPDATE" Wheeler Associate, INC (1988)
[Non-Patent Document 6]
W. Baran, The European Business and Technical Outlook for NdFeB Magnets "Nov. (1989).
[Non-Patent Document 7]
G. FIG. X. Huang, W.C. M. Gao, S .; F. Yu ,: "Application of Melt-Spun Nd-Fe-B Bonded Magnet to the Micro-motor", Proc. of the 11 ^th International Rare-Earth Magnetsand Their Applications, Pittsburgh, USA, pp. 583-595, (1990)
[Non-Patent Document 8]
M. Tokunaga, N .; Nozawa, K .; Iwasaki, M .; Endoh, S, Tanigawa and H .; Harada: IEEE Trans. Magn. , Vol. 25, 3561 (1989)
[Non-Patent Document 9]
H. Sakamoto, M .; Fujikura and T.S. Mukai: J.M. Appl. Phys. , Vol. 69, 5382 (1991)
[Non-Patent Document 10]
M. Doser, V .; Panchanactan, and R.S. K. Misra: J.M. Appl. Phys. , Vol. 70, 6603 (1991)
[Non-Patent Document 11]
T. Takeshita, and R.S. Nakayama: Proc. of the 11th International Works on Rare-Earth Magnets and Their Applications, Pittsburk, PA. , Vol. 1,49 (1990)
[0008]
[Problems to be solved by the invention]
By the way, from the mid 1980's to the present, research on improving the magnetic properties of melt spun ribbons has been conducted continuously and actively, but the (BH) max of the ribbon is 160 kJ / m. ³ Nd which is obtained by crushing the melt spun ribbon obtained by crushing the ribbon. ₂ Fe ₁₄ (BH) max of a magnetically isotropic bonded magnet obtained by fixing a B-based rare earth magnet powder with a resin is industrially ~ 80 kJ / m. ³ It is. Therefore, from the time of 1985 until recently, Nd ₂ Fe ₁₄ The increase in (BH) max of a magnetically isotropic rare-earth bonded magnet in which a B-based rare-earth magnet powder is fixed with a resin has not progressed much.
[0009]
Notwithstanding the above, a so-called permanent magnet rotor type or permanent magnet field type brushless is widely used for controlling and driving electric and electronic devices such as computer peripherals and printers to which the present invention is directed. With respect to motors and DC motors, there is an ever-increasing demand for smaller and lighter motors and higher output with the advancement of the electric and electronic equipment. Accordingly, Nd obtained by pulverizing a melt spun ribbon found in 1986 by the present inventors was used. ₂ Fe ₁₄ A small-diameter annular isotropic bonded magnet in which a B-based rare earth magnet powder is fixed with a resin cannot be said to be useful for the evolution of a small motor any longer.
[0010]
On the other hand, since the late 1980s, Nd ₂ Fe ₁₄ B magnetically anisotropic Nd starting from a melt spun ribbon having a high Nd composition based on the B stoichiometric composition ₂ Fe ₁₄ Research on B-type polycrystalline aggregated rare earth magnet powder has been actively conducted. In a conventional Sm-Co based bonded magnet, a large coercive force HcJ is obtained by finely pulverizing the ingot, whereas Nd ₂ Fe ₁₄ B-based alloy ingots and Nd ₂ Fe ₁₄ Even if the B-based rare earth sintered magnet is pulverized, only a small coercive force HcJ can be obtained. Therefore, magnetically anisotropic Nd ₂ Fe ₁₄ As a starting material for the B-type polycrystalline aggregated rare earth magnet powder, a melt spun ribbon was first studied. In 1989, Tokunaga et al. Nd ₁₄ Fe _80-X B ₆ Ga _X (X = 0.4-0.5), the bulk obtained by hot upsetting (Die-up-set) is mechanically pulverized and anisotropic Nd having a coercive force HcJ1.52 MA / m. ₂ Fe ₁₄ B-type polycrystalline aggregated rare earth magnet powder is prepared and solidified with resin (BH) _max 127 kJ / m ³ [Non-Patent Document 8: M.A. Tokunaga, N .; Nozawa, K .; Iwasaki, M .; Endoh, S, Tanigawa and H .; Harada: IEEE Trans. Magn. , Vol. 25, 3561 (1989)]. In 1991, T.A. Mukai et al. Nd ₁₄ Fe _79.8 B _5.2 Cu ₁ Is hot rolled to obtain an anisotropic Nd having a coercive force HcJ of 1.30 MA / m. ₂ Fe ₁₄ A B-type polycrystalline aggregated rare earth magnet powder is produced [Non-Patent Document 9: H. Sakamoto, M .; Fujikura and T.S. Mukai: J.M. Appl. Phys. , Vol. 69, 5382 (1991)]. Thus, the addition of Ga, Cu, or the like improves hot workability and can suppress the crystal grain size to approximately 500 nm or less. If the crystal grain growth is suppressed, a powder having a particle diameter of approximately 100 μm or more will be a polycrystalline aggregated rare earth magnet powder in which a decrease in coercive force HcJ is suppressed. 1991; Doser, V .; Panchanathan et al. Reported that as a method of pulverizing the bulk after hot working, hydrogen infiltrates from grain boundaries and Nd ₂ Fe ₁₄ BH _X HD (Hydrogen Decrepitation) anisotropic Nd ₂ Fe ₁₄ B-type polycrystalline aggregated rare earth magnet powder solidified with resin (BH) _max 150kJ / m ³ [Non-Patent Document 10: M.S. Doser, V .; Panchanactan, and R.S. K. Misra: J.M. Appl. Phys. , Vol. 70, 6603 (1991)].
[0011]
However, anisotropic Nd obtained by hot-upsetting or hot-rolling the above melt-spun ribbon ₂ Fe ₁₄ The B-based rare earth magnet powder has a defect that an Nd-rich phase exists in the crystal grain boundaries and permanent demagnetization due to intergranular corrosion is easily caused. As a method of overcoming this drawback, a Nd—Fe (Co) —B-based alloy ingot to which elements such as Ga, Zr, and Hf are added is heat-treated in hydrogen and Nd ₂ (Fe, Co) ₁₄ Hydrogenation of phase B (Hydrogenation, Nd ₂ [Fe, Co] ₁₄ B Hx), phase decomposition at 650-1000 ° C. (Decomposition, NdH) ₂ + Fe + Fe ₂ B), dehydrogenation (Desorpsion), and recombination (Recombination), so-called HDDR processing, have been proposed [for example, Non-Patent Document 11: T. et al. Takeshita, and R.S. Nakayama: Proc. of the 11th International Works on Rare-Earth Magnets and Their Applications, Pittsburk, PA. , Vol. 1, 49 (1990)]. Anisotropic Nd produced by this method ₂ Fe ₁₄ The B-type polycrystalline aggregated rare earth magnet powder is composed of only the texture of crystal grains of 0.5 μm or less, and has no Nd-rich phase at the crystal grain boundaries.
[0012]
However, the anisotropic Nd ₂ Fe ₁₄ High (BH) max rare earth bonded magnets using B-type polycrystalline aggregated rare earth magnet powders are often bonded magnets mixed with a binder such as epoxy resin and then compression molded at a pressure of 1 GPa or more. . Therefore, in the case of densification by compression, cracking or damage of the rare earth magnet powder is inevitable. Then, as the surface area increases, a large amount of Nd ₂ Fe ₁₄ The B crystal was newly exposed, and a reduction in the durability as a magnet existed as a fundamental problem, such as a permanent demagnetization increasing due to a change in the structure of the B crystal at high temperature exposure. That is, no matter how high (BH) max anisotropic rare earth bonded magnet is, durability such as magnetic flux loss in a practical temperature range must be ensured.
[0013]
Further, the anisotropic Nd ₂ Fe ₁₄ The high (BH) max rare earth bonded magnet using the B-based polycrystalline aggregated rare earth magnet powder is a prototype made of a cylinder or a cube, and is actually Nd obtained by pulverizing a melt spun ribbon. ₂ Fe ₁₄ It is not used for general small motors, such as a magnetically isotropic bonded magnet in which a B-based rare earth magnet powder is fixed with a resin. The reason is that the magnet mounted on the small motor targeted by the present invention has a shape of Nd obtained by pulverizing a melt spun ribbon. ₂ Fe ₁₄ This is because the shape of the magnetically isotropic bonded magnet in which the B-based rare earth magnet powder is fixed with resin is, for example, an annular magnet having a diameter of 25 mm or less or an arc-shaped magnet having a thickness of 1 mm or less. Therefore, instead of a simple cylinder or cube like the anisotropic high (BH) max rare earth bonded magnets once produced, for example, a radially anisotropic rare earth bonded magnet magnetically anisotropic in the radial direction is required. Become. As a means for generating such a radial orientation magnetic field, as described in Japanese Patent Application Laid-Open No. 57-170501, a magnetic yoke is shown in FIG. A mold is used in which 01a, 01b and non-magnetic yoke 02a, 02b are alternately combined and magnetized coils 03a, 03b are arranged on the outside. In this method, in order to generate a radially oriented magnetic field (FLUX) having a predetermined strength in the annular mold cavity MC, a high voltage current type power supply is used and the magnetomotive force is increased. However, in order to effectively focus the magnetic flux (FLUX) excited by the magnetized coils 03a and 03b from the outer periphery of the annular molding cavity MC by the magnetic yokes 01a and 01b into the annular molding cavity MC, the magnetic yoke is required. Inevitably, the magnetic paths 01a and 01b have to be long, and particularly when the annular molding cavity MC has a small diameter (or long), a considerable amount of magnetomotive force is consumed as leakage magnetic flux. As a result, there is a problem that the orientation magnetic field (FLUX) of the annular mold cavity MC is reduced. For example, the diameter is 25 mm or less, the wall thickness is 1 to 2 mm, and the ratio of length to diameter (L / D = 0.5-1). In the case of the ring magnet of the above, the degree of orientation of the magnet powder was reduced, and in the case of the anisotropic rare earth bonded magnet, the reduction of (BH) max due to the reduction in diameter was inevitable.
[0014]
[Means for Solving the Problems]
As described above, the present invention is widely used for controlling and driving electric and electronic devices such as computer peripherals, printers, etc., and is a so-called permanent magnet rotor type or permanent magnet field type. With regard to brushless motors and DC motors, in order to respond to the demand for smaller and lighter and higher output of small motors with the high performance of the devices concerned, higher (BH) max is required. Nd crushed melt spun ribbon that does not progress much ₂ Fe ₁₄ B-type rare earth magnet powder is replaced with a magnetically isotropic bonded magnet fixed with resin, and anisotropic Nd ₂ Fe ₁₄ The present invention relates to the disclosure of a manufacturing technique in which the (BH) max of a magnet does not decrease even when the diameter is reduced or the thickness is reduced using a B-based polycrystalline aggregate type rare earth magnet powder.
[0015]
For example, any circular or arc shape applicable to a small motor, for example, 160 kJ / m ³ If the above-mentioned high (BH) max rare earth bonded magnet can be easily manufactured regardless of the size of the magnet, a small motor with high output and high efficiency can be provided, and the performance of electric and electronic equipment can be improved. Prompt. The reason is that Nd, which is a crushed conventional melt spun ribbon ₂ Fe ₁₄ The (BH) max of the isotropic rare earth bonded magnet in which the B-based rare earth magnet powder is fixed with resin is 80 kJ / m as described above. ³ It is. On the other hand, 160 kJ / m in any circular or arc shape ³ If a high (BH) max rare earth bonded magnet as described above can be manufactured, the air gap magnetic flux density between the motor magnet and the iron core is approximately the square root of the ratio of (BH) max, and this depends on the design concept of the small motor. This is because about 1.4 times higher output, 30% smaller size and lighter weight are expected.
[0016]
In order to produce a high (BH) max rare earth bonded magnet corresponding to various magnet shapes of a small motor, the present invention uses a magnetically anisotropic polycrystalline aggregated rare earth magnet powder as a core material. The present invention comprising preparing a compound precursor having cells with single domain particle type rare earth magnet powder through a binder component medium, and comprising at least the precursor, a powdery thermoplastic polymer compound, and a binder component Is densified while applying an orientation magnetic field in the plasticizing temperature range of the powdery thermoplastic polymer compound. Then, the polycrystalline aggregated rare earth magnet powder which is the core material of the compound precursor is mechanically dispersed by the dispersing action of the compressive stress by the cells of the precursor and the buffering action by the plastic deformation of the powdery thermoplastic polymer compound. A compact green compact can be produced while suppressing damage. Thereafter, the obtained green compact is heated to crosslink the binder components to form a continuous phase, whereby the hybrid rare earth bonded magnet according to the present invention is obtained. Furthermore, the technology of transforming the shape of the magnet by plastic working in order to accommodate the magnet shape of various small motors while maintaining (BH) max is the gist of the present invention.
[0017]
(Action)
Hereinafter, the present invention will be described in more detail.
[0018]
Here, in the production of the high (BH) max rare-earth bonded magnet according to the present invention, as is well known, a technique for making the magnetic anisotropic rare-earth magnet powder highly oriented and densified is fundamental. First, it goes without saying that compression molding is more advantageous than injection molding or extrusion molding for increasing the density of rare earth bonded magnets. On the other hand, regarding the generation of the orientation magnetic field of the magnet powder in the general compression molding in a magnetic field, it is necessary that: 1. electromagnet, 2. pulse magnetic field; There is known a method using a mold in which a permanent magnet is embedded. Here, a high coercive force rare earth magnet powder requires a high orientation magnetic field (static magnetic field) to achieve high orientation, and it is well known that the electromagnet 1 is used for an orientation (demagnetization) magnetic field. At this time, there are known many types of compression molding in an orientation magnetic field such as a horizontal orientation magnetic field in which the compression direction is perpendicular to the magnetic field direction, a vertical orientation magnetic field in which the compression direction and the magnetic field direction are the same, a radial orientation magnetic field, and a polar orientation magnetic field. From the viewpoint of orientation, a transverse orientation magnetic field in which the compression direction and the magnetic field direction are orthogonal to each other, and a vertical orientation magnetic field in which the compression direction and the magnetic field direction are the same are more advantageous than the radial orientation field and the polar orientation field. Therefore, the application of the alignment magnetic field of the present invention employs a horizontal alignment magnetic field or a vertical alignment magnetic field.
[0019]
In the present invention, a compound precursor having cells in a single domain particle type rare earth magnet powder through a medium of a binder component using a magnetically anisotropic polycrystalline aggregated rare earth magnet powder as a core material, at least the precursor A compound composed of a body and a powdery thermoplastic polymer compound, a binder component is densified while applying an orientation magnetic field in a plasticization temperature region of the powdery thermoplastic polymer compound, and the precursor cell is formed. By compressive stress dispersing action and the buffering action by plastic deformation of the powdery thermoplastic polymer compound while suppressing mechanical damage between the polycrystalline aggregated rare earth magnet powders, which are the core material of the compound precursor, (B) a method for producing a hybrid rare earth bonded magnet in which the binder component is crosslinked by heating the obtained green compact to form a continuous phase; ) To maintain max diverse small motor - is the magnet to correspond to the magnet shape data as to the essence of the technique of shape conversion in plastic working.
[0020]
Next, the present invention will be described in more detail with reference to the drawings. First, the magnetically anisotropic polycrystalline aggregated rare earth magnet powder referred to in the present invention is shown in the schematic diagram of FIG. In the figure, 1 is a polycrystalline aggregated rare earth magnet powder, 11G is a crystal grain constituting the polycrystalline aggregated rare earth magnet powder 1, and 11 (006) is an axis of easy magnetization existing in each crystal grain. I have. Here, many easy axes 11 (006) existing in the polycrystalline aggregate type rare earth magnet powder 1 are aligned in substantially the same direction as shown in the figure. Such polycrystalline aggregated rare earth magnet powder 1 according to the present invention is prepared by Nd prepared by hot upsetting (Die-Up-Setting). ₂ Fe ₁₄ B-based rare earth magnet powder (for example, M. Doser, V. Panchanathan; "Pulverizing anisotropic rapidly solidified Nd-Fe-B materials for bonded magnetnet"; J. Ap. 19, P. 70, p. Magnetically anisotropic Nd prepared by HDDR treatment (hydrogen decomposition / recombination) ₂ Fe ₁₄ Nd of B-based rare earth magnet powder, that is, Nd-Fe (Co) -B-based alloy ₂ (Fe, Co) ₁₄ Hydrogenation of phase B ( H hydrogenation, Nd ₂ [Fe, Co] ₁₄ BHx), phase decomposition at 650-1000 ° C ( D ecomposition, NdH ₂ + Fe + Fe ₂ B), dehydrogenation ( D esorpsion), recombination ( R HDDR processing (T. Takeshita and R. Nakayama: Proc. of the 10) ^th RE Magnets and Their Applications, Kyoto, Vol. 1,551 1989) produced by magnetically anisotropic Nd ₂ Fe ₁₄ It is a B-based rare earth magnet powder. The surface of the rare earth magnet powder is inactivated beforehand, such as Zn, which has been photolyzed beforehand (for example, K. Machida, K. Noguchi, M. Nushimura, Y. Hamaguchi, G. Adachi, Proc. 9th). Int.Workshop on Rare-Earth Magnets and Ttheir Applications, Sendai, Japan, II, 845 2000, or K. Machida, Y. Hamaguchi, K. Noguchi, G. Adagi, G. Adagi. ^th Annual conference on Magnetcs in Japan, 28aC-6 2001).
[0021]
Next, the single domain particle type rare earth magnet powder referred to in the present invention is schematically shown in FIG. In the drawing, reference numeral 2 denotes a magnet powder, and 2 (006) denotes an easy axis of magnetization existing in a magnetic domain of the magnet powder 2. One easy axis 2 (006) per single magnetic domain particle type rare earth magnet powder. Exists. Such a single-domain particle type rare earth magnet powder according to the present invention is a magnetically anisotropic Sm prepared by RD (oxidation-reduction) treatment. ₂ Fe ₁₇ N ₃ -Based single-domain particle-type rare earth magnet powder, or powder obtained by previously inactivating the surface of the powder, Sm ₁ Co ₅ One or more of the single magnetic domain particle type rare earth magnet powders can be used in combination as needed.
[0022]
Next, a compound precursor that forms a cell with a single-domain particle-type rare earth magnet powder through a medium of a binder component, using the polycrystalline aggregated rare earth magnet powder referred to in the present invention as a core material, will be described. First, the polycrystalline aggregated anisotropic rare earth magnet powder 1 according to the present invention is previously coated with a liquid epoxy oligomer as shown in FIG. However, in FIG. 4 (a), reference numeral 1 denotes a polycrystalline aggregated rare earth magnet powder, and reference numeral 3 denotes a binder constituent component whose surface is coated. As the binder component 3, a liquid epoxy oligomer having tackiness is reduced in viscosity with, for example, a ketone-based organic solvent, and the organic solvent solution is applied to a microcrystal that can be present on the surface of the polycrystalline aggregated rare earth magnet powder 1. It is desirable to make the crack penetrate. Further, as shown in FIG. 4B, the single domain particles according to the present invention as shown in FIG. 3 using the binder component 3 as a medium so as to cover the entire surface of the polycrystalline aggregated rare earth magnet powder 1 The rare earth magnet powder 2 is adhered. Thus, by a relatively simple process, a compound precursor having a cell with a single domain particle type rare earth magnet powder through a medium of a binder component, using the polycrystalline aggregated rare earth magnet powder as the core material according to the present invention as a core material. Body A can be made. Further, the binder component 4 as shown in FIG. 4 (c) can be optionally used in the cell portion of the compound precursor A in FIG. 4 (b) as needed. For example, in FIG. 4, if the binder component 3 serving as the medium of the cell is a liquid epoxy oligomer, the binder component 4 used in combination with the cell material may be a powder latent epoxy curing agent or the like. Can be.
[0023]
In the above compound precursor A, if the average particle diameter of the polycrystalline aggregated rare earth magnet powder 1 serving as the core material is less than 50 μm or exceeds 150 μm, the (BH) max of the powder itself generally decreases. Therefore, it is desirable that the polycrystalline aggregate type rare earth magnet powder 1 has an average particle diameter of 50 to 150 μm. The single-domain particle type rare earth magnet powder 2 serving as a cell of the compound precursor A has a magnetically anisotropic Sm having an average particle diameter of 2 to 5 μm. ₂ Fe ₁₇ N _x (X ≒ 3) -based rare earth magnet powder or SmCo ₅ It is preferable to use a rare earth magnet powder. If the average particle size is less than 2 μm, densification by compression does not proceed, and if it exceeds 5 μm, the powder itself decreases in (BH) max. Further, the single magnetic domain particle type rare earth magnet powder 2 serving as a cell of the compound precursor A contains 5 wt. % Or more, 60 wt. % Or less. 5 wt. %, The effect of suppressing damage due to direct contact between the polycrystalline aggregated rare earth magnet powders 1 serving as the core material during densification by compression is lost. %, The density of the hybrid rare earth bonded magnet according to the present invention decreases. On the other hand, the single-domain particle type rare earth magnet powder cell forming medium 3 of the compound precursor A is a room temperature liquid epoxy oligomer having two or more oxirane rings in the molecular chain, and the cell constituent material of the compound precursor A It is preferable to add a latent crosslinking agent of the powder to the oxirane ring, since the formation of the continuous phase by the thermosetting of the binder becomes strong.
[0024]
Next, the compound precursor A as described above is mixed with the thermoplastic polymer compound powder 5 as shown in FIG. 6 to finish the compound B according to the present invention. Here, the thermoplastic polymer compound powder 5 has a functional group capable of reacting with the cell forming medium of the compound precursor A, and chemically forms a continuous phase with other binder components by thermal curing of the green compact. Are preferred. As such a thermoplastic polymer compound powder 5, for example, when the single domain particle type rare earth magnet powder cell forming medium 3 of the compound precursor A is an epoxy oligomer, amino active hydrogen capable of reacting with the oxirane ring is used. Examples thereof include polyamide and / or polyamideimide powder having (-NHCOO-).
[0025]
When the compound B according to the present invention as described above is filled in a mold cavity heated to the plasticizing temperature region of the powdery thermoplastic polymer compound 5, the temperature rises and the powdery thermoplastic polymer compound 5 as shown in FIG. The thermoplastic polymer compound 5 softens and comes into contact with the compound precursor A. On the other hand, the viscosity of the epoxy oligomer-3 of the cell forming medium is also reduced, and the binding force of the cell to the single-domain particle type rare earth magnet powder 2 is reduced. When the orientation magnetic field H is applied in such a state, the easily magnetized magnetic domains 11 (006) and 22 (006) of the polycrystalline aggregate type rare earth magnet powder 1 of the core material and the single magnetic domain particle type rare earth magnet powder 2 of the cell are changed. Both are magnetized in the direction of application of the magnetic field H and are oriented as shown in FIG.
[0026]
As described above, when the compressive pressure is applied after the application of the orientation magnetic field, the entire compound B starts to be densified. At this time, the polycrystalline aggregated rare earth magnet powder 1 does not directly contact each other due to the buffering action of the cell forming medium 3, the single domain particle type rare earth magnet powder 2, and the powdery thermoplastic polymer compound 5 as shown in FIG. Densification as in (a). At this time, as shown in FIG. 7 (a) 2A, a part of the single-domain particle type rare earth magnet powder 2 is densified so as to be taken into the powdery thermoplastic polymer compound 5, and on the other hand, as shown in FIG. 2) As shown in 2B, the compression stress is dispersed by interposing between the polycrystalline aggregated rare earth magnet powders 1. Also, the powdery thermoplastic polymer compound moves while plastically deforming into a relatively large space formed between the polycrystalline aggregated rare earth magnet powders 1 as shown in FIG. Densification ends when the compression pressure reaches a maximum. At this time, as shown in FIG. 7 (b), the boundary (Boundary) of the polycrystalline aggregate type rare earth magnet powder 1 is a single magnetic domain particle type rare earth magnet powder 2, a binder component 3 such as epoxy oligomer, The binder component 4 such as a water-soluble epoxy curing agent and the powdery thermoplastic polymer compound 5 are in a composite state with almost no voids.
[0027]
The green compact according to the present invention can be obtained by removing the above-mentioned FIG. 7 (b) from the mold cavity. Then, by heating the green compact, a binder component 3 such as an epoxy oligomer, a binder component 4 such as a latent epoxy curing agent, and a powdery thermoplastic polymer as shown in FIG. A hybrid type rare earth bonded magnet according to the present invention having a configuration in which the polycrystalline aggregate type rare earth magnet powder 1 and the single domain particle type rare earth magnet powder 2 are fixed in a predetermined shape by the continuous phase 6 in which the compounds 5 are cross-linked to each other is obtained. . The hybrid rare-earth bonded magnet can be transformed into an arc shape or an annular shape by plastic working. In order to make the magnet into an arc shape, the magnet shown in FIG. 8A is transformed from a sheet shape into an arc shape by hot stamping (shaping by plastic working using a warm forming die). In order to form an annular shape, the continuous phase 6 of the magnet is extended in one direction as shown in FIG. The hybrid rare-earth bonded magnet according to the present invention in which the binder is stretched in this way can change its shape from a sheet shape to a ring shape. When the stretching ratio is changed from a sheet shape having a thickness of 1.1 mm or less to an annular shape with the stretching ratio of 10% or less, the polycrystalline aggregated rare earth magnet powder 1 and the single domain particle type rare earth magnet powder 2 are stretched. A decrease in orientation can be suppressed.
[0028]
The (BH) max of the hybrid rare-earth bonded magnet according to the present invention, which has been converted from an arc shape into an annular shape as described above, is 160 kJ / m. ³ It is desirable to make the above. If the maximum thickness of the arc-shaped magnet is 1 mm or less, and the diameter of the annular magnet is 25 mm or less, the miniaturization and high output of the small DC motor and brushless motor according to the present invention can be further promoted. .
[0029]
The method for treating the poly-oligomer aggregate type anisotropic rare-earth magnet powder 1 according to the present invention with the epoxy oligomer as the cell forming medium 3 is as follows: first, dissolving the epoxy oligomer in an organic solvent; The solution and the anisotropic rare earth magnet powder are wet-mixed to remove the solvent. In order to increase the crosslink density of the epoxy oligomer, a novolak type epoxy having an epoxy group in the molecular chain or a diglycidyl ether type epoxy which is a condensate of epichlorohydrin and a bisphenol is preferred. Examples of the powdered epoxy curing agent 4 that crosslinks with the epoxy oligomer include one or more selected from the group consisting of dicyandiamide and derivatives thereof, carboxylic dihydrazide, diaminomaleonitrile and hydrazides of derivatives thereof, and the like. it can. These are generally high-melting organic compounds that are hardly soluble in organic solvents, but are adjusted to a particle size of several to several tens μm or less, and physically adhere to anisotropic magnet powder or other thermosetting resin compositions. Those having strong properties are preferred. The dicyandiamide derivatives include, for example, o-tolylbiguanide, α-2,5-dimethylbiquanide, α-ω-diphenylbiguanide, 5-hydroxybutyl-1-biguanide, phenylbiguanide, α-, ω-dimethylbiquanide Anide and the like can be mentioned. Further, examples of the carboxylic acid dihydrazide include succinic hydrazide, adipic hydrazide, isophthalic hydrazide, p-hydroxybenzoic hydrazide and the like. These epoxy resin curing agents are desirably added to the compound by dry mixing. In order to prevent the transfer of the compound to the mold, 0.2 wt. Of one or more selected from higher fatty acids, higher fatty acid amides and higher fatty acid metal soaps having a higher melting point than the set temperature of the mold cavity. . % Or less is desirably added to the compound by dry mixing.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited by the examples.
[0031]
(Description of Example 1, Raw Materials)
The polycrystalline aggregated rare earth magnet powder 1 used in the present embodiment is Nd having an anisotropic average particle diameter of 80 μm prepared by HDDR treatment (hydrogen decomposition / recombination). ₂ Fe ₁₄ B-type polycrystalline aggregated rare earth magnet powder (Nd _12.3 Dy _0.3 Fe _64.7 Co _12.3 B _6.0 Ga _0.6 Zr _0.1 ), Single domain particle type rare earth magnet powder 2 is RD (oxidized and reduced) Sm having an average particle diameter of 3 μm. ₂ Fe ₁₇ N ₃ This is a single magnetic domain particle type rare earth magnet powder. Liquid diglycidyl ether terbisphenol A type epoxy oligomer is used as the cell forming medium 3 as a binder component, and a powdery latent epoxy curing agent having a particle diameter of 15 μm or less is used as a curing agent 4 as a binder component. The thermoplastic resin compound 5 includes a polyamide powder containing an adhesive and previously frozen and pulverized to 100 μm or less, and a lubricant having a particle diameter of 10 μm or less (pentaerythritol C17 triester) as an additive to be added as needed. Was selected in this example. The chemical structures of the diglycidyl ether terbisphenol A type epoxy oligomer (Chemical formula 1) and the powdery latent epoxy curing agent (Chemical formula 2) were as follows.
[0032]
Embedded image

[0033]
(NH ₂ NHCOCH ₂ CH ₂ ) ₂ N (CH ₂ ) ₁₁ CONHNH ₂ .. (Chemical 2)
[0034]
(Description of Example 2, Preparation of Compound Precursor)
First, Nd as a core material of the compound precursor according to the present invention ₂ Fe ₁₄ The surface of the B-type polycrystalline aggregated anisotropic rare earth magnet powder 1 was previously coated with a liquid epoxy oligomer (0.5 or 1.0 wt.%) As shown in FIG. In FIG. 4A, reference numeral 1 denotes a polycrystalline aggregated rare earth magnet powder, and reference numeral 3 denotes a surface-coated epoxy oligomer. The epoxy oligomer-3 is diluted with a ketone-based organic solvent (acetone), and the organic solvent solution is allowed to penetrate into the microcracks indicated by arrows in FIG. 9 that may exist on the surface of the polycrystalline aggregated rare earth magnet powder 1. I did it.
[0035]
Next, as shown in FIG. 4 (b), the core material Nd of the compound precursor ₂ Fe ₁₄ The epoxy oligomer-3 on the surface of the B-based polycrystalline aggregate type rare earth magnet powder 1 was used as a cell forming medium, and the Sm according to the present invention as shown in FIG. ₂ Fe ₁₇ N ₃ A single magnetic domain particle type rare earth magnet powder 2 was attached as a cell material (0 to 40 wt.%). As described above, by a relatively simple process, the polycrystalline aggregated rare earth magnet powder according to the present invention is used as a core material, and a single domain particle type rare earth magnet powder is formed through a binder component medium to form cells. Can be prepared. Here, 0.3 wt.% Of binder component 4 (powder-like latent epoxy effect agent) as shown in FIG. 4C was further added to the cell portion of compound precursor A in FIG. 4B. %.
[0036]
(Explanation 3 of embodiment, production of green compact)
The compound precursor A as described above is mixed with a thermoplastic polymer compound powder 5 (here, 3 wt.% Of a polyamide powder containing 10 parts by weight of pentaerythritol C17 triester) as shown in FIG. Thus, Compound B according to the present invention was completed.
[0037]
When the compound B according to the present invention is filled in a mold cavity heated to the plasticizing temperature region (80 ° C.) of the powdery thermoplastic polymer compound 5, the compound rises in temperature and the compound shown in FIG. Thus, the powdery thermoplastic polymer compound 5 softens and comes into contact with the compound precursor A. On the other hand, the viscosity of the epoxy oligomer-3 of the cell forming medium is also reduced, and the binding force of the cell to the single-domain particle type rare earth magnet powder 2 is reduced. When an orientation magnetic field H (2 MA / m) is applied in such a state, the magnetization of the polycrystalline aggregated rare earth magnet powder 1 as the core of the compound precursor A and the single domain particle type rare earth magnet powder 2 as the cell are easily magnetized. Both axes 11 (006) and 22 (006) are magnetized in the direction of application of the orientation magnetic field H, and are oriented as shown in FIG.
[0038]
As described above, after applying the orientation magnetic field, the compression pressure is applied in a state where the orientation magnetic field is applied. Then, densification of the entire compound B starts. At this time, the polycrystalline aggregate type rare earth magnet powder 1 almost directly contacts each other due to the buffering action of the cell forming medium 3, the single domain particle type rare earth magnet powder 2, and the powdery thermoplastic polymer compound 5. And the densification proceeds as shown in FIG. At this time, as shown in FIG. 7 (a) 2A, a part of the single-domain particle type rare earth magnet powder 2 is densified so as to be taken into the powdery thermoplastic polymer compound 5, and on the other hand, as shown in FIG. 2) Disperse the compressive stress generated in the polycrystalline aggregated rare earth magnet powder 1 by intervening between the polycrystalline aggregated rare earth magnet powders 1 as in 2B. Also, the powdery thermoplastic polymer compound may move while plastically deforming into a relatively large space formed between the polycrystalline aggregated rare earth magnet powders 1 as shown in FIG. Then, when the compression pressure reaches the maximum (0.6 to 1.0 GPa), the densification ends. At this time, as shown in FIG. 7 (b), the boundary (Boundary) of the polycrystalline aggregate type rare earth magnet powder 1 is a single magnetic domain particle type rare earth magnet powder 2, a binder component 3 such as epoxy oligomer, The binder component 4 such as a water-soluble epoxy curing agent and the powdery thermoplastic polymer compound 5 are in a composite state with almost no voids.
[0039]
The green compact according to the present invention can be obtained by removing the above-mentioned FIG. 7 (b) from the mold cavity.
[0040]
(Explanation 4 of Example, Production of Hybrid Rare Earth Bonded Magnet)
When the green compact prepared as described above is heated (180 ° C., 15 minutes), a binder component 3 such as an epoxy oligomer and a binder component such as a latent epoxy curing agent are applied as shown in FIG. 4. The present invention having a structure in which the polycrystalline aggregated rare earth magnet powder 1 and the single magnetic domain particle type rare earth magnet powder 2 are fixed in a predetermined shape by the continuous phase 6 in which the powdery thermoplastic polymer compound 5 is cross-linked to each other. Such a hybrid type rare earth bonded magnet is obtained. The hybrid rare-earth bonded magnet can be transformed into an arc shape or an annular shape by plastic working. In order to make it into an arc shape, the magnet shown in FIG. 8A is transformed from a sheet shape into an arc shape by hot stamping (plastic working using a warm forming die). Alternatively, in order to form a desired annular shape, the continuous phase 6 of the magnet is extended in one direction as shown in FIG. The hybrid rare earth bonded magnet according to the present invention in which the binder is stretched in this way can be annularly transformed by winding it from a sheet. When the stretching ratio is changed from a sheet shape having a thickness of 1.1 mm or less to an annular shape with the stretching ratio of 10% or less, the polycrystalline aggregated rare earth magnet powder 1 and the single domain particle type rare earth magnet powder 2 are stretched. A decrease in orientation can be suppressed.
[0041]
(Explanation 5 of Example, Hybrid effect related to high (BH) max)
FIG. 10 shows that the (BH) max of the anisotropic hybrid rare earth bonded magnet according to the present invention is represented by Nd which is the core material of the compound precursor A. ₂ Fe ₁₄ A cell, Sm, is used for the B-based polycrystalline aggregated rare earth magnet powder 1. ₂ Fe ₁₇ N ₃ FIG. 2 is a characteristic diagram in which the ratio (wt.%) Of a system single magnetic domain particle type rare earth magnet powder 2 is plotted. The comparative example shown in FIG. ₂ Fe ₁₇ N ₃ -Based single-domain particle-type rare earth magnet powder 2 is pre-granulated to 350 μm or less using Epoxy Oligomer-3 (0.5 wt.%), And polycrystalline aggregated rare earth magnet powder 1 and powder A compound was prepared by mixing with the thermoplastic resin compound 5 and was made into a magnet under the same molding conditions. The size of the magnet was 8 mm × 8 mm × 8 mm, processed into Pc ≒ 3, magnetized with a 4 MA / m pulsed magnetic field in the oriented direction, and then measured under a measurement magnetic field of Hm ± 1.6 MA / m. It was measured in.
[0042]
As is apparent from FIG. 10, Sm granulated into a compound as in the comparative example. ₂ Fe ₁₇ N ₃ If the system single domain particle type rare earth magnet powder is present, the granules are not dispersed in the system during compression. Therefore, Nd ₂ Fe ₁₄ Granulated Sm is present between the B-based polycrystalline aggregated rare earth magnet powder particles 1. ₂ Fe ₁₇ N ₃ System single domain particle type rare earth magnet powder cannot be contained in a large amount. However, when the compound B composed of the compound precursor A according to the present invention is used, the single domain particle type rare earth magnet powder is well dispersed in the system, depending on the amount of the cell forming medium. Inclusion of higher amounts does not reduce (BH) max. Rather, as is clear from FIG. 10, in the hybrid type rare earth bonded magnets of Examples 1 (0.5 wt.%) And 2 (1.0 wt.%) Of the present invention, the ratio of the single-domain particle type rare earth magnet powder is approximately 5 wt. % To 20 wt. %, Or 30 wt. (BH) max is 160 kJ / m in the range of%. ³ It can be improved so that it exceeds. Also, in the range of the binder content of 2 to 3 wt%, there is no difference in the level of (BH) max in the range of the compression pressure of 0.6 to 1.0 GPa, and both are 160 kJ / m2. ³ (BH) max value that exceeds The level of this (BH) max is determined by Tokunaga et al. ₁₄ Fe _80-X B ₆ Ga _X (X = 0.4-0.5) The bulk obtained by hot upsetting (Die-up-set) is mechanically pulverized. Coercive force HcJ = 1.52 MA / m Anisotropy Nd ₂ Fe ₁₄ (BH) max = 127 kJ / m obtained by hardening a B-type polycrystalline assembly type rare earth magnet powder with a resin ³ Anisotropic rare earth bonded magnet [M. Tokunaga, N .; Nozawa, K .; Iwasaki, M .; Endoh, S, Tanigawa and H .; Harada: IEEE Trans. Magn. , Vol. 25, 3561 (1989)]. Alternatively, M. Doser, V .; Panchanathan et al. Reported that Nd was introduced by infiltrating hydrogen from the grain boundaries of the bulk after hot working. ₂ Fe ₁₄ BH _X HD (Hydrogen Decrepitation) anisotropic Nd ₂ Fe ₁₄ B-type polycrystalline assembly type rare earth magnet powder solidified with resin (BH) max = 150 kJ / m ³ Rare earth bonded magnet [M. Doser, V .; Panchanactan, and R.S. K. Misra: J.M. Appl. Phys. , Vol. 70, 6603 (1991)], the (BH) max of the hybrid rare-earth bonded magnet according to the present invention is clearly higher due to the hybrid effect due to the structure of the compound precursor A.
[0043]
(Explanation 6 of embodiment, Hybrid effect on reduction of initial irreversible magnetic flux loss)
FIG. 11 shows Example 1 of the present invention (Sm ₂ Fe ₁₇ N ₃ Based single domain particle type rare earth magnet powder 10 wt. %), Magnetized with a pulse magnetic field of 4 MA / m, exposed to air at 100 ° C and 120 ° C for 1 hour each, and the amount of magnetic flux before and after the exposure was measured by a search coil extraction method, and the initial irreversible decrease was observed. FIG. 4 is a characteristic diagram in which magnetism is calculated and plotted against the content of a single-domain particle type rare earth magnet powder. As is apparent from the figure, regardless of the exposure temperature, the initial irreversible demagnetization decreases as the amount of the single magnetic domain particle type rare earth magnet powder increases. In particular, 40 wt. %, The initial irreversible magnetic flux loss is reduced by about ２〜 to 比 べ as compared with an anisotropic rare earth bonded magnet containing only polycrystalline aggregated rare earth magnet powder. That is, the hybrid type rare earth bonded magnet according to the present invention can contain a large amount of single domain particle type rare earth magnet powder in a homogeneously dispersed state by the compound precursor A, so that a high level (BH) max can be obtained. A hybrid effect that can simultaneously reduce the initial irreversible magnetic flux loss while securing is obtained.
[0044]
(Explanation 7 of embodiment, Hybrid effect on reduction of long-term irreversible magnetic flux loss)
FIG. 12 shows Example 1 of the present invention (Sm ₂ Fe ₁₇ N ₃ Based single domain particle type rare earth magnet powder 10 wt. %), Magnetized with a pulse magnetic field of 4 MA / m, exposed to air at 100 ° C. for 1000 hours, and the amount of magnetic flux before and after exposure is measured at any time by a search coil extraction method, and irreversible magnetic flux loss FIG. 4 is a characteristic diagram showing a change with time in FIG. However, Comparative Example 2 in FIG. 2 shows the results of a conventional anisotropic rare earth bonded magnet using a liquid epoxy resin as a binder at room temperature. The polycrystalline aggregated rare earth magnet powder used in the magnet of Comparative Example 2 was the same as the Nd having an average particle diameter of 80 μm used in the present invention. ₂ Fe ₁₄ B-type polycrystalline aggregated rare earth magnet powder (Nd _12.3 Dy _0.3 Fe _64.7 Co _12.3 B _6.0 Ga _0.6 Zr _0.1 ). As is clear from the figure, the hybrid rare-earth bonded magnet according to the present invention also reduces long-term irreversible magnetic flux loss. In particular, the permanent magnet flux loss of the hybrid rare-earth bonded magnet of Example 1 of the present invention re-magnetized at 4 MA / m after exposure to high temperature for 1000 hours is about 3.3%, which is about 6.5% as compared with 6.5% of Comparative Example 2. It also decreases by a factor of two. That is, the hybrid type rare earth bonded magnet according to the present invention can contain a single magnetic domain particle type rare earth magnet powder uniformly and in a large amount by the structure of the compound precursor A, so that the (BH) max is increased and the initial irreversible magnetic flux is increased. It is possible to reduce not only the loss but also the long-term irreversible magnetic flux loss and the permanent magnetic flux loss based on the structural change of the rare earth magnet powder.
[0045]
(Description of Example 8, Observation of Hybrid Tissue)
FIG. 13A shows Example 1 of the present invention (Sm ₂ Fe ₁₇ N ₃ Based single domain particle type rare earth magnet powder 10 wt. %) Is a characteristic diagram showing the same fracture state of the magnet as that of FIG. FIG. 13B shows a fracture surface of Comparative Example 2 (a conventional anisotropic rare earth bonded magnet using a liquid epoxy resin at room temperature of 3 wt.% As a binder) described in Example 7 of the present invention. It is a characteristic diagram. However, both show the results of observation by a scanning electron microscope. Comparing FIGS. 13A and 13B, in FIG. ₂ Fe ₁₄ It is confirmed that microcracks have occurred in the B-type polycrystalline aggregated rare earth magnet powder and that the magnet powder itself has been crushed. This was caused by the inability to withstand the compressive stress (0.8 GPa) during magnet molding. On the other hand, in FIG. 13A according to the present invention, as shown in FIG. ₂ Fe ₁₄ The microcracks of the B-type polycrystalline aggregated rare earth magnet powder and the crushing status of the magnet powder are difficult to understand. This is due to the formation of the compound precursor cell, Sm ₂ Fe ₁₇ N ₃ -Based single-domain particle-type rare-earth magnet powder with Nd ₂ Fe ₁₄ This is because the breakage of the B-based polycrystalline aggregated rare earth magnet powder was suppressed, and as a result, the (BH) max was increased in the explanation 5 of the embodiment, and further, the explanation was given in the explanation 6 of the embodiment and the explanation 7 of the embodiment. It can be concluded that the magnetic flux loss was reduced.
[0046]
(Explanation 6 of Embodiment, Shaping by plastic working and basic performance of motor)
Invention Example 1 (Sm ₂ Fe ₁₇ N ₃ Based single domain particle type rare earth magnet powder 10 wt. %) (BH) max = 162 kJ / m according to the present invention under the same conditions as (%). ³ And a plate-shaped hybrid rare-earth bonded magnet having a thickness of 0.97 mm. Subsequently, the plate-shaped hybrid rare earth bonded magnet was formed into a thin arc-shaped magnet having an inner radius of 3.55 mm, an outer radius of 3.65 mm, a maximum thickness of 0.88 mm, and a length of 10 mm by stamping. However, the plastic working conditions are a temperature of 120 ° C., a pressure of 0.5 GPa, and a pressure holding time of 0.1 sec. The thin-walled arc-shaped magnet according to the present invention formed into a final shape under such conditions did not generate cracks, and the desired dimensional accuracy was secured. On the other hand, as Comparative Example 3, magnetically isotropic Nd ₂ Fe ₁₄ B-type polycrystalline aggregated rare earth magnet powder (Nd ₁₂ Fe ₇₇ Co ₅ B ₆ ) Was compression-molded into a thin circular arc shape having an inner radius of 3.55 mm, an outer radius of 3.65 mm, a maximum thickness of 0.88 mm, and a length of 10 mm together with an epoxy resin. The (BH) max of this magnet after 4 MA / m pulse magnetization was 72 kJ / m. ³ Met.
[0047]
When the two types of arc-shaped magnets are pulse-magnetized at 4 MA / m, the magnetic fluxes of the two magnets are compared with the isotropic Nd ₂ Fe ₁₄ It was 1.53 times that of the B-type compression-molded bonded magnet. Next, the two kinds of thin arc-shaped rare earth bonded magnets were used as permanent magnet fields of a small DC motor having an outer diameter of 16 mm and an axial length of 19 mm, and their torque constants Kt were determined. As a result, the Kt of the DC motor using the magnet according to the present invention as a field is 0.0016 mN · m / mA, and the isotropic Nd ₂ Fe ₁₄ It was 1.45 times the Kt of the DC motor using the B-based compression-bonded bonded magnet as the field.
On the other hand, Invention Example 1 (Sm ₂ Fe ₁₇ N ₃ Based single domain particle type rare earth magnet powder 10 wt. %) (BH) max = 162 kJ / m according to the present invention under the same conditions as (%). ³ And a plate-shaped hybrid rare-earth bonded magnet having a thickness of 0.97 mm. Subsequently, the plate-shaped rare earth bonded magnet was stretched to a thickness of 0.93 mm by warm rolling as shown in FIG. FIG. 15 shows a fractured surface of the magnet stretched in this way. FIG. 13A shows the state before the magnet is stretched. Comparing the fracture surface before and after stretching of the magnet according to FIG. 13A and FIG. 14, it can be seen that the magnet is stretched uniformly.
[0048]
The magnet develops flexibility in the rolling direction. Therefore, it can be shaped into an annular shape having an arbitrary diameter. Needless to say, when the magnet is formed in an annular shape, it is 160 kJ / m in the radial direction. ³ It is nothing but a so-called radially anisotropic rare earth bonded magnet having (BH) max of the class. Therefore, substantially ~ 80 kJ / m ³ Isotropic Nd of (BH) max of class ₂ Fe ₁₄ 1.43 times the Kt of the DC motor using the B-based compression-bonded bonded magnet as the field was obtained. By the way, the motor efficiency η can be expressed by the following equation, where P is the mechanical output and W is the loss.
[0049]
η = [P / (P + W)] (Equation 3)
Therefore, isotropic Nd ₂ Fe ₁₄ It can be concluded that high efficiency of the motor by high output, which is one of the objects of the present invention, can be realized with respect to a typical small DC motor using a B-based compression-bonded bonded magnet as a field. .
[0050]
【The invention's effect】
In order to provide a high (BH) max hybrid rare earth bonded magnet corresponding to various magnet shapes for small motors, the present invention provides a magnetically anisotropic polycrystalline aggregated rare earth magnet powder. A compound precursor having cells in a single domain particle type rare earth magnet powder was prepared via a medium of a binder component as a substance, and was composed of at least the precursor, a powdery thermoplastic polymer compound, and a binder component. The compound according to the present invention is densified while applying an orientation magnetic field in the plasticizing temperature range of the powdery thermoplastic polymer compound. Then, the polycrystalline aggregated rare earth magnet powder which is the core material of the compound precursor is mechanically dispersed by the dispersing action of the compressive stress by the cells of the precursor and the buffering action by the plastic deformation of the powdery thermoplastic polymer compound. A compact green compact can be produced while suppressing damage. Thereafter, the obtained green compact is heated to crosslink the binder components to form a continuous phase, whereby the hybrid rare earth bonded magnet according to the present invention is obtained. Furthermore, the technology of transforming the shape of the magnet by plastic working in order to accommodate the magnet shape of various small motors while maintaining (BH) max is the gist of the present invention. As a result, the anisotropic Nd ₂ Fe ₁₄ Even if the diameter is reduced or the thickness is reduced by using the B-type polycrystalline aggregated rare earth magnet powder, not only does the (BH) max of the magnet not decrease, but also the durability typified by irreversible magnetic flux loss can be improved. .
[0051]
For example, any circular or arc shape applicable to a small motor, for example, 160 kJ / m ³ Since the high (BH) max rare earth bonded magnet described above can be easily manufactured regardless of the size of the magnet, a small motor with high output and high efficiency can be provided, and high performance of electric and electronic equipment can be provided. Promote the change. The reason is that Nd, which is a crushed conventional melt spun ribbon ₂ Fe ₁₄ (BH) max of the isotropic rare earth bonded magnet in which the B-based rare earth magnet powder is fixed with resin is approximately 80 kJ / m. ³ It is. On the other hand, 160 kJ / m in any circular or arc shape ³ This is because a high (BH) max rare earth bonded magnet as described above can be manufactured.
[0052]
The air gap magnetic flux density between the motor magnet and the iron core is approximately the square root of the ratio of (BH) max. Therefore, depending on the design concept of the small motor, the output is increased by about 1.4 times and the size is reduced by 30%. It is expected that the weight and weight will be reduced.
[0053]
As described above, the present invention is widely used for controlling and driving electric and electronic devices such as computer peripherals, printers, etc., and is a so-called permanent magnet rotor type or permanent magnet field type. With respect to brushless motors and DC motors, it is possible to meet the demands for further downsizing and lightening of small motors and higher output power, with higher performance of the devices.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a radially oriented magnetic field forming die.
FIG. 2 is a conceptual diagram of an anisotropic polycrystalline aggregate type rare earth magnet powder.
FIG. 3 is a conceptual diagram of anisotropic single domain particle type rare earth magnet powder.
FIG. 4 (a) is a conceptual diagram showing a composition state a of a compound precursor.
(B) Conceptual diagram showing the composition state b of the compound precursor
(C) Conceptual diagram showing the composition state c of the compound precursor
FIG. 5 is a conceptual diagram of a compound containing a compound precursor.
FIG. 6A is a conceptual diagram showing filling into a cavity and orientation state a.
(B) Conceptual view showing cavity filling and orientation state b
FIG. 7A is a conceptual diagram showing a state “a” of compound densification.
(B) Conceptual diagram showing state b of compound densification
FIG. 8A is a conceptual diagram showing the molecular orientation of a binder before stretching.
(B) Conceptual diagram showing molecular orientation of binder after stretching
FIG. 9 is a characteristic diagram showing microcracks of a polycrystalline aggregated rare earth magnet powder.
FIG. 10 is a characteristic diagram showing (BH) max of an anisotropic hybrid type rare earth bonded magnet.
FIG. 11 is a characteristic diagram showing initial irreversible magnetic flux loss of an anisotropic hybrid type rare earth bonded magnet.
FIG. 12 is a characteristic diagram showing long-term irreversible magnetic flux loss of an anisotropic hybrid type rare earth bonded magnet;
FIG. 13 is a characteristic diagram showing a fracture surface structure of an anisotropic hybrid type rare earth bonded magnet.
FIG. 14 is a characteristic diagram showing a fracture surface structure of a stretched anisotropic hybrid rare earth bonded magnet.
[Explanation of symbols]
A Compound precursor
1 Polycrystalline aggregated rare earth magnet powder (core material)
2 Single domain particle type rare earth magnet powder (cell forming substance)
3 Binder constituents to be cell forming media
4 Components of the binder for crosslinking

Claims (21)

Compound precursor A in which cells are formed of single domain particle type rare earth magnet powder through a medium of a binder component using a magnetically anisotropic polycrystalline aggregated rare earth magnet powder as a core material, at least the precursor and The compound composed of the powdery thermoplastic polymer compound and the binder component is densified while applying an orientation magnetic field in the plasticization temperature region of the powdery thermoplastic polymer compound, and the precursor is compressed by a cell. The dispersion of the stress, and the buffering action due to the plastic deformation of the powdery thermoplastic polymer compound 5, densify while suppressing the mechanical damage of the polycrystalline aggregated rare earth magnet powder which is the core material of the compound precursor, A method for producing a hybrid rare earth bonded magnet in which a binder phase is crosslinked by heating the obtained green compact to form a continuous phase 6. Hybrid of claim 1, wherein the core substance of the compound precursor polycrystalline aggregated rare earth magnet powder a Nd 2 _Fe 14 _B based rare earth magnet powder of magnetically anisotropic with an average particle diameter of 50~150μm Manufacturing method of rare earth bonded magnet. The single domain particle type rare earth magnet powder serving as a cell of the compound precursor is a magnetically anisotropic Sm ₂ Fe ₁₇ N _x (x ≒ 3) based rare earth magnet powder having an average particle diameter of 1 to 5 μm. 2. The method for producing a hybrid rare earth bonded magnet according to item 1. 2. The hybrid rare earth bonded magnet according to claim 1, wherein the single magnetic domain particle type rare earth magnet powder serving as a cell of the compound precursor is a magnetically anisotropic SmCo5-based rare earth magnet powder having an average particle diameter of 1 to _{5 [} mu] m. Production method. The single domain particle type rare earth magnet powder serving as a cell of the compound precursor contains 5 wt. % Or more, 60 wt. %. The method for producing a hybrid type rare earth bonded magnet according to claim 1, wherein 2. The method for producing a hybrid type rare-earth bonded magnet according to claim 1, wherein the single-domain particle-type rare-earth magnet powder cell forming medium of the compound precursor is a liquid epoxy oligomer at room temperature having two or more oxirane rings in a molecular chain. . The method for producing a hybrid type rare-earth bonded magnet according to claim 1, wherein a latent crosslinking agent of a powder for an oxirane ring is added as a cell constituent material of the compound precursor. The method for producing a hybrid type rare earth bonded magnet according to claim 1, wherein the thermoplastic polymer compound powder has a functional group capable of reacting with the cell forming medium of the compound precursor. The thermoplastic polymer compound powder is a polyamide or / and polyamideimide powder having amino active hydrogen (-NHCOO-) capable of reacting with the oxirane ring of the cell forming medium of the single domain particle type rare earth magnet powder cell forming medium of the compound precursor. Item 3. The method for producing a hybrid type rare earth bonded magnet according to Item 1. 2. The rare earth bonded magnet according to claim 1, further comprising a step of transforming the shape of the hybrid type rare earth bonded magnet by plastic working. 2. The method for producing a hybrid rare earth bonded magnet according to claim 1, wherein the continuous phase formed by the crosslinking reaction of the binder component is stretched and the shape is changed from a sheet shape to a ring shape. 10. The method for producing a hybrid type rare earth bonded magnet according to claim 1, wherein the shape is changed from a sheet shape having a thickness of 1.1 mm or less to an annular shape with an elongation ratio of 10% or less. The method for producing a hybrid type rare-earth bonded magnet according to claim 1, wherein the continuous phase formed by the crosslinking reaction of the binder components is unequally stretched and the shape is changed from a sheet shape to an arc shape. 2. The method for producing a hybrid rare earth bonded magnet according to claim 1, wherein the shape is changed from a sheet shape to an arc shape by hot stamping. Maximum energy - product (BH) max is a manufacturing method of a hybrid rare earth bonded magnet according to claim 1, wherein at 160 kJ / ^{m 3} or more. The diameter of the annular magnet is 25mm or less, the maximum energy - claim 1 product (BH) max is 160 kJ / ^{m 3} or more, according to claim 10, claim 11, claim 12, hybrid rare earth bonded magnet of claim 15, wherein Manufacturing method. 16. The hybrid type according to claim 1, wherein the arc-shaped magnet has a maximum thickness of 1 mm or less and a maximum energy product (BH) max of 160 kJ / m ³ or more. Manufacturing method of rare earth bonded magnet. A brushless motor equipped with the radially anisotropic annular hybrid rare earth bonded magnet according to any one of claims 1, 10, 11, 12, and 15. A DC motor mounted with the radially anisotropic annular hybrid type rare earth bonded magnet according to claim 1, claim 10, claim 11, claim 12, or claim 15. A brushless motor equipped with the radially anisotropic arc-shaped hybrid rare-earth bonded magnet according to claim 1, claim 10, claim 13, claim 14, or claim 15. A DC motor on which the radially anisotropic arc hybrid hybrid rare earth bonded magnet according to any one of claims 1, 10, 13, 14, and 15 is mounted.

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