JP2020123703A - Rare earth bonded magnet manufacturing method - Google Patents
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本発明は磁気特性に優れ、かつ優れた強度を有する希土類系ボンド磁石の製造方法に関する。 The present invention relates to a method for producing a rare earth-based bonded magnet having excellent magnetic properties and excellent strength.
希土類系永久磁石は高い磁気特性を有しており、今日、様々な分野で使用されている。希土類系永久磁石は使用する原料粉末や製造方法により焼結磁石とボンド磁石に大きく分類されるが、希土類系ボンド磁石（以下、単にボンド磁石と称する）は、希土類系焼結磁石に比べて形状の自由度が大きく、さらに、磁石粉末同士の間に絶縁物である樹脂が存在している為、電気抵抗が高いという利点を有している。しかしながら、ボンド磁石は磁石粉末を樹脂バインダーによって結合した構造であるため、希土類系焼結磁石に比べて磁石強度が低くならざるをえず、高い磁石強度を要する用途への採用は困難であった。 Rare earth-based permanent magnets have high magnetic properties and are used in various fields today. Rare earth permanent magnets are roughly classified into sintered magnets and bonded magnets depending on the raw material powder used and the manufacturing method. Rare earth bonded magnets (hereinafter simply referred to as bond magnets) are more compact than rare earth sintered magnets. Has a large degree of freedom, and further has the advantage of high electric resistance because the resin, which is an insulator, exists between the magnet powders. However, since the bonded magnet has a structure in which magnet powders are bonded by a resin binder, the magnet strength is inevitably lower than that of the rare earth-based sintered magnet, and it is difficult to adopt it in applications requiring high magnet strength. ..
国際公開第2012/118001号（特許文献１）には、混錬時に添加する樹脂量と有機溶剤量を一定の範囲として作製したボンド磁石用コンパウンドを強圧縮することによって、高い成形体密度を有するとともに、高い磁気特性を有するボンド磁石を製造する方法が開示されている。 International Publication No. 2012/118001 (Patent Document 1) has a high compact density by strongly compressing a bond magnet compound produced with a resin amount and an organic solvent amount added during kneading within a certain range. At the same time, a method of manufacturing a bonded magnet having high magnetic properties is disclosed.
特開2017-34097号（特許文献２）には、通常の圧縮ボンド磁石や特許文献１に記載の強圧縮ボンド磁石に採用可能で、高温における機械的強度に優れる成形用樹脂が開示されている。 Japanese Unexamined Patent Application Publication No. 2017-34097 (Patent Document 2) discloses a molding resin that can be used in a normal compression bonded magnet and the strong compression bonded magnet described in Patent Document 1 and that has excellent mechanical strength at high temperatures. ..
一方、特開平4-27102号（特許文献3）には、希土類系磁石粉末を常温で固体状のエポキシ樹脂、硬化剤、及び硬化促進剤を含有するバインダー1によって成形し、バインダー1を熱硬化させた成形体に対し、エポキシ樹脂と硬化剤（イミダゾール化合物）を含むバインダー2を真空含浸し、バインダー2を熱硬化させることによってボンド磁石を製造する方法が開示されている。 On the other hand, in JP-A-4-27102 (Patent Document 3), a rare earth magnet powder is molded with a binder 1 containing a solid epoxy resin at room temperature, a curing agent, and a curing accelerator, and the binder 1 is thermally cured. There is disclosed a method for producing a bonded magnet by vacuum-impregnating the formed body thus obtained with a binder 2 containing an epoxy resin and a curing agent (imidazole compound) and thermally curing the binder 2.
しかしながら、特許文献１に記載のボンド磁石の磁石強度は実用的なものにとどまっており、高い磁石強度を必要とする用途への採用は通常の成形体密度のボンド磁石よりもさらに困難である。また、特許文献２に記載の樹脂を採用することによって、ある程度機械的強度は向上するものの、例えば、より高い強度が求められる高速回転するモーターなどの用途には決して十分な強度を有しているとは言えない。 However, the magnet strength of the bonded magnet described in Patent Document 1 is limited to a practical value, and it is more difficult to apply it to an application requiring high magnet strength than a bonded magnet having a normal compact density. Further, although the mechanical strength is improved to some extent by adopting the resin described in Patent Document 2, for example, it has nevertheless sufficient strength for applications such as high-speed rotating motors requiring higher strength. It can not be said.
さらに、特許文献3に記載の方法によれば、強度に優れるエポキシ樹脂によって成形して熱硬化させた成形体に対し、さらに強度に優れるエポキシ樹脂を前記成形体に存在する空隙に含浸させた後、熱硬化させるため、前記空隙がエポキシ樹脂によって埋められ、磁石強度の大幅な向上が期待できる。しかしながら、含浸樹脂組成物（バインダー2）は硬化剤（イミダゾール化合物）を含んでおり、真空含浸装置の樹脂槽内で、常温でも徐々に硬化が始まってしまうためにポットライフを有しており、頻繁に含浸樹脂を入れ替えたり、真空含浸装置を清掃したりする必要があり生産効率が悪い。 Further, according to the method described in Patent Document 3, for a molded body that is molded and thermoset with an epoxy resin having excellent strength, after impregnating the voids existing in the molded body with an epoxy resin having further excellent strength Since the resin is heat-cured, the voids are filled with an epoxy resin, and it is expected that the magnet strength will be significantly improved. However, the impregnated resin composition (binder 2) contains a curing agent (imidazole compound), and has a pot life in the resin tank of the vacuum impregnation device because curing begins gradually even at room temperature, Since it is necessary to frequently replace the impregnating resin and clean the vacuum impregnating device, production efficiency is poor.
従って、本発明の目的は、高い磁石強度を有する希土類系ボンド磁石を優れた生産効率で製造する方法を提供することである。 Therefore, an object of the present invention is to provide a method for producing a rare earth-based bonded magnet having high magnet strength with excellent production efficiency.
上記目的に鑑み鋭意検討の結果、本発明者らは、希土類ボンド磁石の製造工程において、例えば、希土類系ボンド磁石を成形する際に使用する成型用エポキシ樹脂組成物に、過剰の硬化剤を含ませて硬化させ、過剰の硬化剤を残存させた状態で希土類系ボンド磁石を作製した後、さらに硬化剤を含まない樹脂組成物を含浸させ、前記残存する硬化剤によって硬化させることによって、高い磁石強度を有する希土類系ボンド磁石を優れた生産効率で製造することができることを見出し本発明に想到した。 As a result of intensive studies in view of the above object, the present inventors have found that, in the process of manufacturing a rare earth bonded magnet, for example, a molding epoxy resin composition used when molding a rare earth bonded magnet contains an excessive curing agent. After making a rare earth-based bonded magnet in a state where it is hardened and the excess hardener remains, a resin composition containing no hardener is further impregnated, and the remaining hardener is hardened to obtain a high magnet. The inventors have found that it is possible to manufacture a strong rare earth-based bonded magnet with excellent production efficiency, and have conceived the present invention.
すなわち、本発明の希土類系ボンド磁石の製造方法は、
希土類系急冷合金磁石粉末、エポキシ樹脂及び硬化剤を混練した混練物を圧縮して熱処理することにより得られるボンド磁石成形体に、前記硬化剤で硬化可能なエポキシ樹脂を含浸させて含浸成形体を得るエポキシ樹脂含浸工程と、
前記含浸成形体を熱処理して希土類系ボンド磁石を得る熱処理工程とを含み、
前記ボンド磁石成形体は、前記硬化剤が残存し、
前記ボンド磁石成形体及び前記含浸成形体に硬化剤は含浸させず、
前記熱処理工程では、前記ボンド磁石成形体中に残存する前記硬化剤により、前記エポキシ樹脂含浸工程により前記ボンド磁石成形体に含浸させた前記エポキシ樹脂を硬化させることを特徴とする。
That is, the method for producing a rare earth-based bonded magnet of the present invention is
A bond magnet molded body obtained by compressing and heat-treating a kneaded material obtained by kneading a rare earth-based quenched alloy magnet powder, an epoxy resin, and a curing agent is impregnated with an epoxy resin curable with the curing agent to form an impregnated molded body. An epoxy resin impregnation step of obtaining,
And a heat treatment step of heat-treating the impregnated molded body to obtain a rare earth-based bonded magnet,
In the bonded magnet compact, the curing agent remains,
A curing agent is not impregnated into the bonded magnet molded body and the impregnated molded body,
In the heat treatment step, the epoxy resin impregnated in the bonded magnet compact in the epoxy resin impregnation step is cured by the curing agent remaining in the bonded magnet compact.
前記含浸は真空加圧含浸であるのが好ましい。 The impregnation is preferably vacuum pressure impregnation.
本発明によれば、高い磁石強度を有する希土類系ボンド磁石を優れた生産効率で製造できる。 According to the present invention, a rare earth-based bonded magnet having high magnet strength can be manufactured with excellent production efficiency.
本発明の方法は、例えば、過剰の硬化剤を含有する成形用樹脂組成物を用いて成形及び硬化したボンド磁石成形体に対し、硬化剤を含有しないエポキシ樹脂（含浸用樹脂組成物）を含浸させて熱処理することにより、ボンド磁石成形体に残存する硬化剤によって含浸させたエポキシ樹脂を硬化させることを特徴とする方法であり、磁石強度の高いボンド磁石を得ることができるとともに、硬化剤を含まない含浸用樹脂組成物はポットライフが長く、樹脂の入れ替えや樹脂槽の清掃のサイクルが長いので生産効率が良い。 In the method of the present invention, for example, a bond magnet molded article molded and cured using a molding resin composition containing an excess of a curing agent is impregnated with a curing agent-free epoxy resin (impregnation resin composition). This is a method characterized by curing the epoxy resin impregnated with the curing agent remaining in the bonded magnet molded body by heat treatment, and it is possible to obtain a bond magnet with high magnet strength and to cure the curing agent. A resin composition for impregnation that does not contain it has a long pot life and a long cycle of resin replacement and cleaning of a resin tank, resulting in good production efficiency.
以下、図１を参照しながら本発明の希土類系ボンド磁石の製造方法を詳細に説明する。 Hereinafter, the method for manufacturing the rare earth-based bonded magnet of the present invention will be described in detail with reference to FIG.
(1) 希土類系急冷合金粉末を準備する工程S1
まず、希土類系急冷合金粉末を準備する。本発明で使用できる希土類系急冷合金粉末に特段制限はない。例えば、所定の組成の合金の溶湯をメルトスピニング法やストリップキャスト法などのロール急冷法により急冷して作製した急冷合金薄帯を粉砕して製造したものが挙げられる。好適な希土類系急冷合金磁石粉末としては、例えば、米国特許第4802931号に記載のNd-Fe-B系急冷合金磁石粉末が挙げられる。
(1) Step S1 of preparing a rare earth-based quenched alloy powder
First, a rare earth-based quenched alloy powder is prepared. There is no particular limitation on the rare earth-based quenched alloy powder that can be used in the present invention. For example, the alloy may be produced by crushing a quenched alloy ribbon produced by rapidly cooling a melt of an alloy having a predetermined composition by a roll quenching method such as a melt spinning method or a strip casting method. Examples of suitable rare earth-based quenched alloy magnet powders include Nd—Fe—B-based quenched alloy magnet powders described in US Pat. No. 4,802,931.
(2) 成形用樹脂溶液を準備する工程S2
次に、エポキシ樹脂（成形用樹脂）及び硬化剤を配合した成形用樹脂組成物を有機溶剤等で溶解して成形用樹脂溶液を準備する。使用できる成形用樹脂組成物（エポキシ樹脂と硬化剤との組合せ）は、含まれる硬化剤が、後述の含浸用樹脂（エポキシ樹脂）も硬化できるような組合せであれば特に制限はない。成形用樹脂組成物は2種類以上のエポキシ樹脂や、硬化促進剤などを含有してもよい。このような成形用樹脂組成物としては、例えば、特許文献２記載の樹脂組成物や、DIC社製エピクロン4050、三菱ケミカル社製JER7007Pなどが挙げられる。
(2) Step S2 of preparing a molding resin solution
Next, a molding resin composition containing an epoxy resin (molding resin) and a curing agent is dissolved in an organic solvent or the like to prepare a molding resin solution. The molding resin composition (combination of epoxy resin and curing agent) that can be used is not particularly limited as long as the curing agent contained therein is a combination that can also cure the impregnating resin (epoxy resin) described below. The molding resin composition may contain two or more kinds of epoxy resins, a curing accelerator and the like. Examples of such a molding resin composition include the resin composition described in Patent Document 2, Epicron 4050 manufactured by DIC, and JER7007P manufactured by Mitsubishi Chemical.
エポキシ樹脂と硬化剤との配合比は、硬化剤が成形用樹脂のエポキシ樹脂と含浸用樹脂のエポキシ樹脂の双方を完全に硬化できる量を含むように設定される。すなわち、成形用樹脂組成物中のエポキシ樹脂を硬化させるのに必要な量に対して過剰の硬化剤を含み、後述の熱処理工程S5によって得られるボンド磁石成形体に硬化剤が残存するよう配合する。通常、エポキシ樹脂と硬化剤とを配合する場合、その配合比は完全にエポキシ樹脂を硬化できるよう、理論的な反応量に対してある程度過剰の硬化剤を含むように設定するため、反応に寄与しなかった硬化剤はボンド磁石内に残存する。含浸用樹脂はその含浸量がわずかであるため、通常の成形用樹脂の組成物を硬化させた後に残存する硬化剤で含浸用樹脂を十分に硬化させることができる。 The compounding ratio of the epoxy resin and the curing agent is set so that the curing agent includes an amount capable of completely curing both the epoxy resin of the molding resin and the epoxy resin of the impregnating resin. That is, an excessive amount of a curing agent is contained with respect to the amount necessary to cure the epoxy resin in the molding resin composition, and the curing agent is compounded so that the curing agent remains in the bond magnet molding obtained by the heat treatment step S5 described below. .. Normally, when mixing an epoxy resin and a curing agent, the mixing ratio is set so that the curing agent can be completely cured, and a certain amount of excess curing agent relative to the theoretical reaction amount is included, thus contributing to the reaction. The curing agent that has not been left remains in the bonded magnet. Since the impregnating resin has a small amount of impregnation, the impregnating resin can be sufficiently cured by the curing agent remaining after curing the ordinary molding resin composition.
有機溶剤は、常温で気体となる揮発性の有機溶剤が好ましい。好適に使用され得る有機溶剤としては、例えば、アセトン、メチルエチルケトン、メチルイソブチルケトン、ベンゼン、トルエン、キシレンが挙げられる。安全性や取扱い性の観点から、メチルエチルケトンなどのケトン類が最も好ましい。 The organic solvent is preferably a volatile organic solvent that becomes a gas at room temperature. Examples of the organic solvent that can be suitably used include acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene and xylene. From the viewpoint of safety and handleability, ketones such as methyl ethyl ketone are most preferable.
成形用樹脂溶液は、上記のようにエポキシ樹脂と硬化剤とを含む成形用樹脂組成物を有機溶剤で溶解することによって準備してもよいが、エポキシ樹脂を有機溶剤で溶解したものに硬化剤を混合することで成形用樹脂溶液を得てもよく、硬化剤を有機溶剤で溶解したものにエポキシ樹脂を混合することで成形用樹脂溶液を得てもよい。さらに、エポキシ樹脂や硬化剤は、溶剤可溶型の樹脂に限定されず、水性や無溶剤型の樹脂を用いることもできる。 The molding resin solution may be prepared by dissolving a molding resin composition containing an epoxy resin and a curing agent as described above in an organic solvent, but a curing agent may be prepared by dissolving the epoxy resin in an organic solvent. The resin solution for molding may be obtained by mixing, or the resin solution for molding may be obtained by mixing an epoxy resin with a solution of a curing agent in an organic solvent. Furthermore, the epoxy resin and the curing agent are not limited to the solvent-soluble type resin, and an aqueous or solventless type resin may be used.
(3) 希土類系ボンド磁石用コンパウンドを作製する工程S3
続いて、工程S1で準備した希土類系急冷合金粉末と工程S2で準備した成形用樹脂溶液とを混練し、有機溶剤を揮発させることにより希土類系ボンド磁石用コンパウンドを作製する。混練に使用する成形用樹脂溶液は、混練される希土類系急冷合金粉末を100質量％としたとき、0.5質量％以上5.0質量％以下のエポキシ樹脂と、3質量％以上7質量％以下の有機溶剤とを含有するのが好ましい。有機溶剤の含有量が3質量％未満であると、混練の際、樹脂が磁石粉末表面に行き渡るまでに有機溶剤が揮発してしまい、均一被覆ができない恐れがある。また、有機溶剤の割合が7質量％を超えると有機溶剤が揮発するまでに時間がかかり、生産性の面から好ましくない。このような割合で混練して、混練中に有機溶剤を揮発させることにより、個々の粉末粒子の表面が樹脂によって薄くかつ均一に被覆されたコンパウンドを作製することができる。好ましい実施形態において、コンパウンド中の樹脂は希土類系急冷合金の磁石粉末粒子を90%以上の被覆率で被覆し、その樹脂の厚さは0.1μm以上1μm以下である。このようなコンパウンドは磁石粉末粒子が高い被覆率で薄く均一に被覆されている為、磁石粉末粒子同士が接しても導通し難く、最終的に高い電気抵抗を有するボンド磁石を得ることができる。続く圧縮成形時の金型の損傷を低減するためには、コンパウンドにステアリン酸カルシウムなどの潤滑剤などを添加・混合するのが望ましい。
(3) Step S3 of producing compound for rare earth bond magnet
Then, the rare earth-based quenched alloy powder prepared in step S1 and the molding resin solution prepared in step S2 are kneaded, and the organic solvent is volatilized to prepare a compound for a rare earth-based bonded magnet. The molding resin solution used for kneading is an epoxy resin of 0.5% by mass or more and 5.0% by mass or less and an organic solvent of 3% by mass or more and 7% by mass or less, when the mass of the rare earth-based quenched alloy powder to be kneaded is 100% by mass. It is preferable to contain and. If the content of the organic solvent is less than 3% by mass, the organic solvent may volatilize before the resin reaches the surface of the magnet powder during kneading, and uniform coating may not be possible. Further, if the proportion of the organic solvent exceeds 7% by mass, it takes time for the organic solvent to volatilize, which is not preferable in terms of productivity. By kneading in such a ratio and volatilizing the organic solvent during the kneading, a compound in which the surface of each powder particle is thinly and uniformly coated with the resin can be produced. In a preferred embodiment, the resin in the compound covers the magnet powder particles of a rare earth-based quenched alloy with a coverage of 90% or more, and the resin has a thickness of 0.1 μm or more and 1 μm or less. In such a compound, since the magnet powder particles are thinly and uniformly coated with a high coverage, it is difficult to conduct even if the magnet powder particles come into contact with each other, and finally a bonded magnet having a high electric resistance can be obtained. In order to reduce damage to the mold during subsequent compression molding, it is desirable to add and mix a lubricant such as calcium stearate with the compound.
(4) 圧縮成形体を作製する工程S4
次に、工程S3で得られた希土類系ボンド磁石用コンパウンドを圧縮して圧縮成形体を作製する。この圧縮成形工程では、圧縮成形体の密度が希土類系急冷合金粉末の真密度の70％以上90％以下の範囲になるように希土類系ボンド磁石用コンパウンドを圧縮するのが好ましい。このような圧縮成形体を得るためには、成形圧力は80 MPa以上2000 MPa以下の範囲であるのが好ましく、200 MPa以上1000 MPa以下の範囲であるのがより好ましい。成形圧力が80 MPa未満であると、高い磁石密度が得られにくい。また、2000 MPaを超えると、金型への負荷が大きくなりすぎるため好ましくない。圧縮成形に用いるプレス装置としては、例えば、メカ式冷間プレス機や特許文献１に記載の超高圧粉末プレス装置が挙げられる。本発明の方法は、特許文献１記載の強圧縮高密度磁石に限定されることなく、汎用の圧縮ボンド磁石にも適用可能であり、本発明の方法によって得られる希土類系ボンド磁石は高い磁石強度が必要な用途に好適に採用される。
(4) Step S4 of producing a compression molded body
Next, the compound for rare earth bond magnets obtained in step S3 is compressed to produce a compression molded body. In this compression molding step, it is preferable to compress the compound for rare earth based bonded magnet so that the density of the compression molded product is in the range of 70% to 90% of the true density of the rare earth based quenched alloy powder. In order to obtain such a compression molded body, the molding pressure is preferably in the range of 80 MPa or more and 2000 MPa or less, and more preferably in the range of 200 MPa or more and 1000 MPa or less. If the molding pressure is less than 80 MPa, it is difficult to obtain a high magnet density. On the other hand, if it exceeds 2000 MPa, the load on the mold becomes too large, which is not preferable. Examples of the press machine used for compression molding include a mechanical cold press machine and an ultrahigh pressure powder press machine described in Patent Document 1. The method of the present invention is not limited to the strong compression high-density magnet described in Patent Document 1, but can be applied to general-purpose compression bonded magnets, and the rare earth-based bonded magnet obtained by the method of the present invention has high magnet strength. It is suitable for applications that require
汎用の圧縮ボンド磁石に本発明を適用する場合には、希土類系ボンド磁石用の材料、他製造条件、含浸条件を汎用の圧縮ボンド磁石に合わせ設定すればよい。 When the present invention is applied to a general-purpose compression bond magnet, the material for the rare earth-based bond magnet, other manufacturing conditions, and the impregnation condition may be set according to the general-purpose compression bond magnet.
(5) 圧縮成形体を熱処理してボンド磁石成形体を作製する工程S5
こうして圧縮成形された圧縮成形体を熱処理することにより、成形用樹脂が硬化してなるボンド磁石成形体が得られる。熱処理条件は使用する樹脂の硬化条件に準ずればよいが、熱処理温度は、好ましくは150℃以上300℃以下であり、より好ましくは175℃以上250℃以下である。希土類系急冷合金粉末としてNd-Fe-B系急冷合金粉末を採用する場合、特に酸化され易いため、熱処理雰囲気は、10 Pa以下の減圧雰囲気中（特に、真空度1 Pa以下の真空中）、Arガスや窒素ガスなどの不活性ガス雰囲気中などの非酸化性雰囲気が好ましい。同様に酸化防止の観点から、熱処理時間（前記熱処理温度での保持時間）は、好ましくは1分以上4時間以下であり、より好ましくは5分以上1時間以下である。
(5) Step S5 of heat-treating the compression molded body to produce a bonded magnet molded body
By heat-treating the compression-molded body thus compression-molded, a bonded magnet molded body obtained by curing the molding resin is obtained. The heat treatment conditions may be in accordance with the curing conditions of the resin used, but the heat treatment temperature is preferably 150°C or higher and 300°C or lower, more preferably 175°C or higher and 250°C or lower. When Nd-Fe-B quenching alloy powder is used as the rare earth quenching alloy powder, it is particularly easily oxidized, so the heat treatment atmosphere is a reduced pressure atmosphere of 10 Pa or less (especially in a vacuum of 1 Pa or less), A non-oxidizing atmosphere such as an atmosphere of an inert gas such as Ar gas or nitrogen gas is preferable. Similarly, from the viewpoint of preventing oxidation, the heat treatment time (holding time at the heat treatment temperature) is preferably 1 minute or more and 4 hours or less, and more preferably 5 minutes or more and 1 hour or less.
前述したように、成形用樹脂組成物はエポキシ樹脂を硬化させるに対して過剰の硬化剤を含むので、圧縮成形体の熱処理によって得られたボンド磁石成形体には硬化剤が残存する。 As described above, since the molding resin composition contains an excess amount of the curing agent with respect to the curing of the epoxy resin, the curing agent remains in the bonded magnet molded body obtained by the heat treatment of the compression molded body.
(6) ボンド磁石成形体に含浸用樹脂（エポキシ樹脂）を含浸させて含浸成形体を作製する工程S6
次に、エポキシ樹脂を含む含浸用樹脂組成物を有機溶剤等で溶解して含浸用樹脂溶液を準備する。この含浸用樹脂組成物は硬化剤を含まない。使用できる含浸用樹脂としては、単独では硬化しにくく、成形用樹脂に含まれる硬化剤によって硬化されるものであれば他に特に制限はないが、例えばエポキシ樹脂が使用できる。エポキシ樹脂の種類としてはグリシジルエーテル型、グリシジルエステル型、グリシジルアミン型、脂環型が挙げられる。含浸用樹脂は、特にエポキシ樹脂を含むものが好ましく、エポキシ樹脂以外の樹脂を含んでいても良い。含浸用樹脂は、有機溶剤に溶解して溶液とすることができれば常温で固体であっても良い。含浸用樹脂溶液は、水や溶剤でさらに希釈しても良い。
(6) Step S6 of making an impregnated compact by impregnating the bonded magnet compact with an impregnating resin (epoxy resin)
Next, the impregnating resin composition containing an epoxy resin is dissolved with an organic solvent or the like to prepare an impregnating resin solution. This impregnating resin composition does not contain a curing agent. The impregnating resin that can be used is not particularly limited as long as it is hard to cure by itself and is hardened by the curing agent contained in the molding resin, but an epoxy resin can be used, for example. Examples of the epoxy resin include glycidyl ether type, glycidyl ester type, glycidyl amine type, and alicyclic type. The impregnating resin is particularly preferably an epoxy resin, and may contain a resin other than the epoxy resin. The impregnating resin may be solid at room temperature as long as it can be dissolved in an organic solvent to form a solution. The impregnating resin solution may be further diluted with water or a solvent.
続いて、工程S5で得られたボンド磁石成形体に対し、含浸用樹脂溶液を含浸させて含浸成形体を作製する。含浸の方法は、真空加圧法、真空法、加圧法、浸漬法、遠心法等を採用することができる。特に真空加圧含浸法が好ましい。これらの方法で含浸処理する際には、含浸用樹脂溶液及びボンド磁石成形体を加熱して含浸処理するのが好ましい。加熱することで含浸用樹脂溶液がボンド磁石成形体に含浸されやすくなる。 Subsequently, the bonded magnet molded body obtained in step S5 is impregnated with an impregnating resin solution to prepare an impregnated molded body. As a method of impregnation, a vacuum pressure method, a vacuum method, a pressure method, a dipping method, a centrifugal method or the like can be adopted. The vacuum pressure impregnation method is particularly preferable. When the impregnation treatment is performed by these methods, it is preferable to heat the impregnation resin solution and the bonded magnet molded body to perform the impregnation treatment. By heating, the impregnating resin solution is easily impregnated into the bonded magnet molding.
(7) 含浸成形体を熱処理して希土類系ボンド磁石を作製する工程S7
続いて、工程S6で作製した含浸成形体を熱処理して希土類系ボンド磁石を作製する。含浸用樹脂組成物は硬化剤を含まないが、工程S5で得られたボンド磁石成形体には硬化剤が残存しているので、ボンド磁石成形体に含浸させたエポキシ樹脂は、この残存する硬化剤によって熱処理で硬化する。
(7) Step S7 of heat-treating the impregnated compact to produce a rare earth-based bonded magnet
Then, the impregnated compact produced in step S6 is heat-treated to produce a rare earth-based bonded magnet. Although the resin composition for impregnation does not contain a curing agent, the curing agent remains in the bonded magnet molded body obtained in step S5. The agent cures by heat treatment.
特許文献３のように硬化剤を含む含浸用樹脂組成物を使用する場合、常温でも徐々に含浸用樹脂の硬化が始まってしまう。そのため含浸用樹脂組成物にはポットライフがあり、ポットライフが短いと頻繁に樹脂の入れ替えや樹脂槽の清掃が必要になるので、ポットライフができるだけ長い樹脂を使うのが好ましいが、そのような樹脂は硬化時間が長く、かつ硬化温度も高いため、生産効率が悪く、磁気特性を劣化させる恐れがある。このように、硬化剤を含有する含浸用樹脂組成物を用いる場合は、ポットライフと、生産効率及び磁気特性劣化率の両立が難しい。 When an impregnating resin composition containing a curing agent is used as in Patent Document 3, the impregnating resin gradually begins to cure even at room temperature. Therefore, the impregnating resin composition has a pot life, and when the pot life is short, it is necessary to frequently replace the resin and clean the resin tank. Therefore, it is preferable to use a resin having a long pot life. Since the resin has a long curing time and a high curing temperature, the production efficiency is poor and the magnetic properties may be deteriorated. As described above, when an impregnating resin composition containing a curing agent is used, it is difficult to satisfy both pot life, production efficiency, and magnetic property deterioration rate.
これに対して本発明の方法においては、成形用樹脂に過剰の硬化剤を含有させて、成形用樹脂硬化後も硬化剤をボンド磁石中に残存させることにより、硬化剤を含まない含浸用樹脂を含浸させて熱処理した場合は、前記残存する硬化剤によって含浸用樹脂を硬化させることができるので、ポットライフ、生産効率、磁気特性の劣化率及び磁石強度のすべてを解決できることができる。 On the other hand, in the method of the present invention, an impregnating resin containing no curing agent is obtained by allowing the molding resin to contain an excessive amount of the curing agent and allowing the curing agent to remain in the bond magnet even after the curing of the molding resin. When impregnated with and heat-treated, the remaining curing agent can cure the impregnating resin, so that all of pot life, production efficiency, deterioration rate of magnetic characteristics, and magnet strength can be solved.
熱処理条件は使用する含浸用樹脂の硬化条件に準ずればよい。希土類系急冷合金粉末としてNd-Fe-B系急冷合金粉末を採用する場合、特に酸化され易いため、熱処理雰囲気はS5工程と同様の非酸化性雰囲気、もしくはオイル中などの酸素を遮断した環境で行うのが好ましい。 The heat treatment conditions may be based on the curing conditions of the impregnating resin used. When Nd-Fe-B quenching alloy powder is used as the rare earth quenching alloy powder, it is particularly easily oxidized, so the heat treatment atmosphere is the same non-oxidizing atmosphere as in the S5 process, or in an environment where oxygen is blocked, such as in oil. It is preferable to carry out.
上記の工程を経て得られたボンド磁石は、成形用樹脂のみを含むボンド磁石成形体に対して磁石強度が1.2倍以上に向上している。また、上記で使用した含浸用樹脂は硬化剤を含んでいないため、硬化剤を含む含浸用樹脂に対して格段にポットライフが長く、真空含浸装置における樹脂の入れ替えや樹脂槽清掃のサイクルが長いため生産効率が高い。また、含浸用樹脂硬化の熱処理を非酸化性雰囲気中で行った場合、ボンド磁石成形体に対する磁気特性劣化率が2.0％以内である。 The bonded magnet obtained through the above steps has a magnetic strength 1.2 times or more higher than that of a bonded magnet molded body containing only the molding resin. Further, since the impregnating resin used above does not contain a curing agent, the pot life is significantly longer than that of the impregnating resin containing a curing agent, and the cycle of resin replacement and resin tank cleaning in the vacuum impregnation device is long. Therefore, the production efficiency is high. Further, when the heat treatment for curing the impregnating resin is performed in a non-oxidizing atmosphere, the deterioration rate of the magnetic properties of the bonded magnet compact is within 2.0%.
工程S5と工程S6との間にボンド磁石成形体の加工工程を追加してもよい。すなわち、ボンド磁石成形体を加工し、加工後のボンド磁石成形体に対して工程S6で準備した含浸用樹脂溶液を含浸させてもよい。また、工程S7の後に加工工程を追加してもよい。すなわち、工程S7で作製したボンド磁石を加工して完成品としてもよい。また、工程S7の後に種々の表面処理を行ってもよい。このように、工程S1〜工程S7は、順番は上記の順であるが、各々の工程の間、後に他の工程を追加してもよい。 You may add the process process of a bonded magnet molded object between process S5 and process S6. That is, the bonded magnet molded body may be processed, and the processed bonded magnet molded body may be impregnated with the impregnating resin solution prepared in step S6. Further, a processing step may be added after the step S7. That is, the bonded magnet produced in step S7 may be processed into a finished product. Further, various surface treatments may be performed after the step S7. As described above, the order of steps S1 to S7 is the order described above, but other steps may be added after each step.
上記の実施形態では、S1工程（希土類系急冷合金粉末を準備する工程）からS7工程（含浸成形体を熱処理して希土類系ボンド磁石を作製する工程）までを説明した。ただし、本発明は上記の実施形態に限定されない。 In the above embodiment, the description has been given from the step S1 (the step of preparing the rare earth-based quenched alloy powder) to the step S7 (the step of heat-treating the impregnated compact to produce the rare earth-based bonded magnet). However, the present invention is not limited to the above embodiment.
例えば、希土類系急冷合金磁石粉末、エポキシ樹脂及び硬化剤を混練した混練物を圧縮して熱処理することにより得られるボンド磁石成形体を入手し、これにエポキシ樹脂を含浸させて含浸成形体を作製し（エポキシ樹脂含浸工程）、この含浸成形体を熱処理することにより（熱処理工程）、希土類系ボンド磁石を得ることができる。 For example, obtain a bonded magnet molding obtained by compressing and heat-treating a kneaded material obtained by kneading a rare earth-based quenched alloy magnet powder, an epoxy resin and a curing agent, and impregnating this with an epoxy resin to produce an impregnated molding (Epoxy resin impregnation step), and the impregnated molded body is heat treated (heat treatment step) to obtain a rare earth-based bonded magnet.
実施例１
希土類系急冷合金粉末として、メルトスピニング法で得られたNd-Fe-B系急冷合金粉末（マグネクエンチ社製MQP-13−9）を準備した。成形用樹脂として、DIC社製無水ビスフェノールA型エポキシ樹脂エピクロン4050、三菱ケミカル社製ビスフェノールF型エポキシ樹脂JER4007P、三菱ケミカル社製硬化剤DICY7（ジシアンジアミド）を配合比45：50：5（質量比）にて準備し、これらをメチルエチルケトン（MEK）に溶解し、成形用樹脂溶液を作製した。MEKの量は混錬される急冷合金粉末の質量を基準として4.5質量％となるようにした。
Example 1
As the rare earth-based quenched alloy powder, Nd-Fe-B-based quenched alloy powder (MQP-13-9 manufactured by Magnequench) was prepared by melt spinning. As molding resin, anhydrous bisphenol A type epoxy resin Epicron 4050 manufactured by DIC, bisphenol F type epoxy resin JER4007P manufactured by Mitsubishi Chemical Co., and curing agent DICY7 (dicyandiamide) manufactured by Mitsubishi Chemical Co., mixing ratio 45:50:5 (mass ratio). Were prepared, and these were dissolved in methyl ethyl ketone (MEK) to prepare a molding resin solution. The amount of MEK was set to 4.5 mass% based on the mass of the quenched alloy powder to be kneaded.
この成形用樹脂溶液とNd-Fe-B系急冷合金粉末とを、急冷合金粉末の質量を基準としてMEKを除く樹脂量が2.0質量％となるように混合し、溶液中のMEKが完全に揮発するまで混錬した。その後、急冷合金粉末の質量を基準として0.07質量％のステアリン酸カルシウムを混合して希土類系ボンド磁石用コンパウンドを作製した。 This molding resin solution and Nd-Fe-B system quenched alloy powder were mixed so that the amount of resin excluding MEK was 2.0% by mass based on the mass of the quenched alloy powder, and MEK in the solution was completely volatilized. Kneaded until done. Then, 0.07 mass% of calcium stearate was mixed based on the mass of the quenched alloy powder to prepare a compound for a rare earth-based bonded magnet.
こうして得られた希土類系ボンド磁石用コンパウンドに対して1000 MPaの成形圧力で圧縮成形を行うことにより圧縮成形体を作製した。この成形体に対し、真空雰囲気中で180℃の温度で2時間熱処理して、外径15.5 mm、内径9.7 mm、高さ2.6 mmのボンド磁石成形体を作製した。このボンド磁石成形体の圧環強度は184.8 N（5個の平均値）、磁力はN極240.4 mT、S極243.6 mT（それぞれ5個の平均値）であった。 A compression molded body was produced by subjecting the compound for a rare earth-based bonded magnet thus obtained to compression molding at a molding pressure of 1000 MPa. The molded body was heat-treated in a vacuum atmosphere at a temperature of 180° C. for 2 hours to prepare a bonded magnet molded body having an outer diameter of 15.5 mm, an inner diameter of 9.7 mm and a height of 2.6 mm. The radial crushing strength of this bonded magnet compact was 184.8 N (5 average value), and the magnetic forces were N pole 240.4 mT and S pole 243.6 mT (5 average value each).
本実施例における圧環強度は、圧環強度試験機を用い、ボンド磁石成形体又はボンド磁石の径方向中央部より圧力をかけ、それらが破壊されるときの強度である。磁力はボンド磁石成形体又はボンド磁石を着磁し、日本電磁測器社製マグネットアナライザーを用いて、N極及びS極それぞれ磁石厚み方向の中央部を測定した。（すべて5個の平均値。） The radial crushing strength in this example is the strength when a pressure is applied from the central portion in the radial direction of the bonded magnet molded body or the bonded magnet using a radial crushing strength tester to break them. The magnetic force was measured by magnetizing a bonded magnet molded body or a bonded magnet and using a magnet analyzer manufactured by Nippon Electro-Magnetic Instruments Co., Ltd. to measure the central portions of the north pole and south pole in the magnet thickness direction. (The average of all 5)
続いて含浸用樹脂溶液（エポキシ樹脂F）を作製した。含浸用樹脂溶液の配合比は、ビスフェノールA型エポキシ樹脂：ポリプロピレングリコールジグリジシルエーテル＝1：1（質量比）であった。 Subsequently, a resin solution for impregnation (epoxy resin F) was prepared. The compounding ratio of the impregnating resin solution was bisphenol A type epoxy resin:polypropylene glycol diglycidyl ether=1:1 (mass ratio).
この含浸用樹脂溶液を真空加圧含浸法にて、ボンド磁石成形体に含浸させて含浸成形体を作製した。続いてこの含浸成形体を表1の3つの条件で熱処理して含浸用樹脂を硬化させ、サンプルNo.1〜3の希土類系ボンド磁石を作製した。これらのボンド磁石に対して、圧環強度及び磁力を測定し、ボンド磁石成形体に対する強度比及び磁力低下率を調べた。結果を表２に示す。 The resin solution for impregnation was impregnated into the bonded magnet compact by a vacuum pressure impregnation method to prepare an impregnated compact. Subsequently, this impregnated molded body was heat-treated under the three conditions shown in Table 1 to cure the impregnating resin, and the rare earth-based bonded magnets of Sample Nos. The radial crushing strength and the magnetic force were measured for these bond magnets, and the strength ratio and the magnetic force decrease rate with respect to the bonded magnet molded body were examined. The results are shown in Table 2.
表2から、これらのボンド磁石はボンド磁石成形体に対して圧環強度が1.2倍以上に向上していた。また磁力低下率はN極及びS極ともに2%以内であった。なお含浸用樹脂溶液（エポキシ樹脂F）は硬化剤を含んでおらず、単独では硬化しないことが確認されている。しかしながら、本実施例においてはボンド磁石成形体に含浸させたエポキシ樹脂Fが十分な硬度で硬化し、含浸前のボンド磁石成形体に対して圧環強度が1.2倍以上に向上したことから、エポキシ樹脂Fはボンド磁石成形体に残存していた硬化剤によって硬化したものと考えられる。 From Table 2, the radial crushing strength of these bonded magnets was improved to 1.2 times or more that of the bonded magnet compact. The rate of decrease in magnetic force was within 2% for both N and S poles. It has been confirmed that the impregnating resin solution (epoxy resin F) does not contain a curing agent and does not cure by itself. However, in this example, the epoxy resin F impregnated in the bond magnet molding was cured with sufficient hardness, and the radial crushing strength was improved to 1.2 times or more compared to the bond magnet molding before impregnation. It is considered that F was cured by the curing agent remaining in the bonded magnet compact.
実施例２
比較例の樹脂として、硬化剤を含む含浸用樹脂溶液（エポキシ樹脂C）を準備した。含浸用樹脂溶液の配合比は、ビスフェノールA型エポキシ樹脂：ポリプロピレングリコールジグリシジルエーテル：3 or 4−メチル-1,2,3,6-テトラヒドロ無水フタル酸＝1：1：2（質量比）であった。
Example 2
As a resin of Comparative Example, a resin solution for impregnation (epoxy resin C) containing a curing agent was prepared. The compounding ratio of the impregnating resin solution is bisphenol A type epoxy resin: polypropylene glycol diglycidyl ether: 3 or 4-methyl-1,2,3,6-tetrahydrophthalic anhydride=1:1:2 (mass ratio). there were.
エポキシ樹脂Fを用いた含浸用樹脂溶液と、エポキシ樹脂Cを用いた含浸用樹脂溶液とを作製し、それらの粘度の時間経過による変化を比較することによってポットライフを比較した。なお、粘度は23℃条件下においてBH型粘度計により測定した。 An impregnating resin solution using the epoxy resin F and an impregnating resin solution using the epoxy resin C were prepared, and pot lives were compared by comparing changes in their viscosities with time. The viscosity was measured with a BH type viscometer under the condition of 23°C.
エポキシ樹脂Fは30日経過後も粘度が500 mP・sであり、含浸に使用できる状態であったが、エポキシ樹脂Cは5日経過後で粘度が10000 mP・sとなり含浸に使用することが難しい状態になった。 Epoxy resin F had a viscosity of 500 mP・s even after 30 days and was in a state of being usable for impregnation, but epoxy resin C had a viscosity of 10,000 mP・s after 5 days and was difficult to use for impregnation. Became.
本発明によれば、高い磁石強度を有する希土類系ボンド磁石を優れた生産効率で製造する方法を得られる。 According to the present invention, it is possible to obtain a method for producing a rare earth-based bonded magnet having high magnet strength with excellent production efficiency.
Claims (2)
前記含浸成形体を熱処理して希土類系ボンド磁石を得る熱処理工程とを含み、
前記ボンド磁石成形体は、前記硬化剤が残存し、
前記ボンド磁石成形体及び前記含浸成形体に硬化剤は含浸させず、
前記熱処理工程では、前記ボンド磁石成形体中に残存する前記硬化剤により、前記エポキシ樹脂含浸工程により前記ボンド磁石成形体に含浸させた前記エポキシ樹脂を硬化させる希土類系ボンド磁石の製造方法。 A bond magnet molded body obtained by compressing and heat-treating a kneaded material obtained by kneading a rare earth-based quenched alloy magnet powder, an epoxy resin, and a curing agent is impregnated with an epoxy resin curable with the curing agent to form an impregnated molded body. An epoxy resin impregnation step of obtaining,
And a heat treatment step of heat-treating the impregnated molded body to obtain a rare earth-based bonded magnet,
In the bonded magnet compact, the curing agent remains,
A hardener is not impregnated into the bonded magnet molded body and the impregnated molded body,
In the heat treatment step, a method for producing a rare earth-based bonded magnet, in which the epoxy resin impregnated in the bond magnet molded body in the epoxy resin impregnation step is cured by the curing agent remaining in the bonded magnet molded body.
前記含浸が真空加圧含浸であることを特徴とする希土類系ボンド磁石の製造方法。 The method for manufacturing a rare earth-based bonded magnet according to claim 1,
The method for producing a rare earth-based bonded magnet, wherein the impregnation is vacuum pressure impregnation.
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| JPH0427102A (en) * | 1990-05-23 | 1992-01-30 | Sumitomo Metal Mining Co Ltd | Resin magnet and its manufacturing method |
| JP2010238929A (en) * | 2009-03-31 | 2010-10-21 | Denso Corp | Reactor and method of manufacturing the same |
| WO2012118001A1 (en) * | 2011-03-02 | 2012-09-07 | 日立金属株式会社 | Rare-earth bond magnet manufacturing method |
| JP2017073479A (en) * | 2015-10-08 | 2017-04-13 | 日立化成株式会社 | Bond magnet hardened body |
| JP2017147387A (en) * | 2016-02-19 | 2017-08-24 | 日立オートモティブシステムズ阪神株式会社 | Internal combustion engine ignition coil and method of manufacturing internal combustion engine ignition coil |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0427102A (en) * | 1990-05-23 | 1992-01-30 | Sumitomo Metal Mining Co Ltd | Resin magnet and its manufacturing method |
| JP2010238929A (en) * | 2009-03-31 | 2010-10-21 | Denso Corp | Reactor and method of manufacturing the same |
| WO2012118001A1 (en) * | 2011-03-02 | 2012-09-07 | 日立金属株式会社 | Rare-earth bond magnet manufacturing method |
| JP2017073479A (en) * | 2015-10-08 | 2017-04-13 | 日立化成株式会社 | Bond magnet hardened body |
| JP2017147387A (en) * | 2016-02-19 | 2017-08-24 | 日立オートモティブシステムズ阪神株式会社 | Internal combustion engine ignition coil and method of manufacturing internal combustion engine ignition coil |
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