JP2020113634A - Bonded magnet and manufacturing method of bonded magnet - Google Patents

Bonded magnet and manufacturing method of bonded magnet Download PDF

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JP2020113634A
JP2020113634A JP2019003080A JP2019003080A JP2020113634A JP 2020113634 A JP2020113634 A JP 2020113634A JP 2019003080 A JP2019003080 A JP 2019003080A JP 2019003080 A JP2019003080 A JP 2019003080A JP 2020113634 A JP2020113634 A JP 2020113634A
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mass
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bonded magnet
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JP7271955B2 (en
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高木 忍
Shinobu Takagi
忍 高木
健二 小玉
Kenji Kodama
健二 小玉
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Daido Steel Co Ltd
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Abstract

To provide a bonded magnet which has heat resistance in a temperature region upon use of a vehicular motor and furthermore can be manufactured safety without adversely affecting environment.SOLUTION: A bonded magnet 20 comprises: a magnetic powder; and a binder 22 that binds powders 21 of the magnetic powder together and is composed of a cellulose nano fiber. The bonded magnet 20 can be manufactured through the following steps of: preparing a cellulose nano fiber-water mixture 11 containing 5 to 15 mass% of the cellulose nano fiber; mixing the cellulose nano fiber-water mixture 11 and a magnet powder 12 so that a rate of a mass of water in a total of the mass of the cellulose nano fiber-water mixture-water mixture 11 and the mass of the magnet powder 12 becomes 9 to 28 mass%, and thereby making a bonded magnet material 13; making formed body 14 by forming the bonded magnet material 13 into a prescribed shape; and vaporizing water from the formed body 14.SELECTED DRAWING: Figure 1

Description

本発明はボンド磁石及びその製造方法に関する。 The present invention relates to a bonded magnet and a method for manufacturing the same.

ボンド磁石は、磁性粉末をバインダと混合して固めたものであって、磁性粉末を焼結した焼結磁石よりも、複雑な形状のものを容易に作製することができること、作製時に高温(焼結磁石では1000℃前後)に加熱する必要がないこと、割れや欠けが生じ難いこと等の特長を有する。 The bonded magnet is one in which magnetic powder is mixed with a binder and hardened, and a magnet having a complicated shape can be more easily manufactured than a sintered magnet obtained by sintering the magnetic powder, and a high temperature (burning) is performed during manufacturing. Binder magnets do not need to be heated to around 1000°C), and cracks and chips are less likely to occur.

従来のボンド磁石では多くの場合、フェノール樹脂やエポキシ樹脂等の樹脂がバインダとして用いられている。しかし、例えば自動車用モータでは使用時に150〜180℃という温度に達するのに対して、フェノール樹脂やエポキシ樹脂等をバインダとしたボンド磁石はこのような温度での耐熱性を有しないため、自動車用モータの磁石として使用することはできない。 In many cases, conventional bonded magnets use a resin such as a phenol resin or an epoxy resin as a binder. However, for example, a motor for automobiles reaches a temperature of 150 to 180°C during use, whereas a bonded magnet using a binder such as a phenol resin or an epoxy resin does not have heat resistance at such a temperature. It cannot be used as a magnet for a motor.

特許文献1に記載のボンド磁石では、バインダとしてポリフェニレンサルファイド(PPS)樹脂を用いている(以下、「PPSボンド磁石」と呼ぶ)。PPSは融点が約280℃であるため、PPSボンド磁石は自動車用モータの使用時における温度域での耐熱性を有する。 In the bonded magnet described in Patent Document 1, a polyphenylene sulfide (PPS) resin is used as a binder (hereinafter referred to as "PPS bonded magnet"). Since PPS has a melting point of about 280° C., the PPS bond magnet has heat resistance in a temperature range when an automobile motor is used.

特開2017-212308号公報JP 2017-212308 JP

PPSボンド磁石を作製する際には、PPS樹脂を融点よりもやや高い温度(通常、300〜320℃)に加熱して溶融させた状態で成形を行う。しかし、PPS樹脂をこのような温度に加熱すると、PPS樹脂が徐々に分解し、硫黄原子を含む分子から成る有毒ガスが発生する。そのため、PPSボンド磁石は、製造時の安全性が低く、且つ、環境に悪影響を与えてしまう。 When the PPS bond magnet is produced, the PPS resin is heated to a temperature slightly higher than the melting point (usually 300 to 320° C.) to be melted and molded. However, when the PPS resin is heated to such a temperature, the PPS resin is gradually decomposed and a toxic gas composed of molecules containing a sulfur atom is generated. Therefore, the PPS bond magnet is low in safety during manufacturing and has an adverse effect on the environment.

本発明が解決しようとする課題は、自動車用モータの使用時における温度域での耐熱性を有しつつ、安全且つ環境に悪影響を与えることなく製造することができるボンド磁石を提供することである。 The problem to be solved by the present invention is to provide a bond magnet which has heat resistance in a temperature range when an automobile motor is in use, and which can be manufactured safely and without adversely affecting the environment. ..

上記課題を解決するために成された本発明に係るボンド磁石は、
磁石粉末と、
該磁石粉末の粒子同士を結合する、セルロースナノファイバから成るバインダと
を備えることを特徴とする。
The bonded magnet according to the present invention made to solve the above-mentioned problems,
Magnet powder,
And a binder made of cellulose nanofibers for binding the particles of the magnet powder to each other.

セルロースナノファイバ(Cellulose Nano Fiber、以下「CNF」とする。)は、セルロース(cellulose)の繊維から成り、植物の繊維を太さが10〜50nm、長さが0.1〜20μmとなるように微細に解きほぐしたものである。 Cellulose Nano Fiber (hereinafter referred to as “CNF”) consists of cellulose fibers, which are finely divided into plant fibers with a thickness of 10 to 50 nm and a length of 0.1 to 20 μm. It is a loosened one.

本発明に係るボンド磁石は、磁石粉末と、該磁石粉末の粒子同士を結合する、CNFから成るバインダを備える。このボンド磁石は、温度を180℃まで上昇させても、バインダであるCNFが溶融することがなく、自動車用モータの使用時の温度域である150〜180℃において耐熱性を有する。 The bonded magnet according to the present invention includes magnet powder and a binder made of CNF that bonds the particles of the magnet powder together. The bonded magnet does not melt the binder CNF even when the temperature is raised to 180° C., and has heat resistance in the temperature range of 150 to 180° C., which is the temperature range when the automobile motor is used.

また、本発明に係るボンド磁石は、以下に述べる方法で製造することにより、有毒ガスが発生することなく、安全且つ環境に悪影響を与えることなく製造することができる。 Further, the bonded magnet according to the present invention can be manufactured by the method described below, without producing toxic gas, safely and without adversely affecting the environment.

本発明に係るボンド磁石の製造方法は、
セルロースナノファイバの含有率が5〜15質量%であるセルロースナノファイバ−水混合物を用意する工程と、
前記セルロースナノファイバ−水混合物と磁石粉末を、該セルロースナノファイバ−水混合物の質量と該磁石粉末の質量の合計に占める水の質量の割合が9〜28質量%となるように混合することによりボンド磁石材料を作製する工程と、
前記ボンド磁石材料を所定の形状に成形することにより成形体を作製する工程と、
前記成形体から水を蒸発させることによりボンド磁石を作製する工程と
を有することを特徴とする。
The method for manufacturing a bonded magnet according to the present invention is
A step of preparing a cellulose nanofiber-water mixture having a content of cellulose nanofibers of 5 to 15% by mass,
By mixing the cellulose nanofiber-water mixture and the magnet powder so that the ratio of the mass of water to the total mass of the cellulose nanofiber-water mixture and the mass of the magnet powder is 9 to 28 mass %. A step of producing a bonded magnet material,
A step of producing a molded body by molding the bonded magnet material into a predetermined shape,
A step of producing a bonded magnet by evaporating water from the molded body.

CNFは、例えば、パルプを水に分散させた分散液を加圧してノズルから噴射させ、噴流同士を衝突させてパルプの繊維を微細に解きほぐすことにより作製される。このような方法で製造されたCNFは、通常はセルロースナノファイバ−水混合物(CNF-水混合物)の状態で販売されている。 The CNF is produced, for example, by pressurizing a dispersion liquid in which pulp is dispersed in water and jetting it from a nozzle, and causing jet streams to collide with each other to finely loosen the fibers of the pulp. The CNF produced by such a method is usually sold in the form of a cellulose nanofiber-water mixture (CNF-water mixture).

CNF−水混合物におけるCNFの含有率を5〜15質量%、且つ、セルロースナノファイバ−水混合物の質量と磁石粉末の質量の合計に占める水の質量の割合(これを、「ボンド磁石材料の含水率」とする)を9〜28質量%とすることにより、ボンド磁石材料を所定の形状に成形した際に、当該形状が維持された成形体を作製することができる。 The content of CNF in the CNF-water mixture is 5 to 15% by mass, and the ratio of the mass of water to the total mass of the cellulose nanofiber-water mixture and the mass of the magnet powder (this is referred to as "the water content of the bonded magnet material". When the bonded magnet material is molded into a predetermined shape, a molded body in which the shape is maintained can be produced.

一方、CNF−水混合物におけるCNFの含有率が5質量%未満であると、ボンド磁石材料全体がペースト状となり、成形することが困難となる。CNF−水混合物におけるCNFの含有率が15質量%を超えると、磁石粉末との混合に時間を要するようになると共に、CNFの分散に偏りが生じ易くなる。また、CNF−水混合物におけるCNFの含有率が15質量%を超えると、成形後の成形体があまり収縮しないことから密度が高くならなかったり、成形体に亀裂が生じ易くなるという問題が生じるうえに、磁気特性が低下する。ボンド磁石材料の含水率が9質量%未満であると、CNFの結着力が弱くなり、成形体から水を蒸発させる際に成形体にひび割れが生じることがある。ボンド磁石材料の含水率が28質量%を超えると、成形体が柔らかくなり、水を蒸発させる際に成形体が膨張したり成形体にひび割れが生じることがある。 On the other hand, if the CNF content in the CNF-water mixture is less than 5% by mass, the entire bonded magnet material will be in a paste form, which makes it difficult to mold. When the content of CNF in the CNF-water mixture exceeds 15% by mass, it takes a long time to mix with the magnet powder, and the CNF is likely to be unevenly dispersed. Further, when the content of CNF in the CNF-water mixture exceeds 15% by mass, the density of the molded product after molding does not increase so much that the density does not become high or cracks easily occur in the molded product. In addition, the magnetic properties deteriorate. When the water content of the bonded magnet material is less than 9% by mass, the binding force of CNF becomes weak, and cracks may occur in the molded body when water is evaporated from the molded body. When the water content of the bonded magnet material exceeds 28% by mass, the molded body becomes soft and the molded body may expand or cracks may occur when the water is evaporated.

前記成形体から水を蒸発させる際には、該成形体を常温に維持した状態で行ってもよいし、加熱してもよい。その際、磁石粉末が酸化することを防ぐために、成形体を真空中(減圧下)又は不活性ガス中に置くことが望ましい。真空中(減圧下)に置くことにより、水の蒸発を促進させることができるという効果も得られる。また、成形体を加熱する場合には、水に含まれる溶存酸素又は磁石粉末の粒子に吸着している吸着酸素等によって、乾燥工程において磁石粉末が酸化することを抑えるために、乾燥温度を150℃以下とすることが望ましい。また、加熱時間は、酸化を抑えるためには短い方が好ましいが、成形体を急激に加熱すると成形体中の水が突沸して成形体の形状が崩れるおそれがある。これらの点を勘案して、加熱時間は予備実験を行うこと等により、適宜定めればよい。成形体の加熱には、ヒーター、白熱ランプ、あるいは電子レンジその他のマイクロ波を用いた加熱装置等を用いることができる。 When water is evaporated from the molded body, the molded body may be maintained at room temperature or heated. At that time, in order to prevent the magnet powder from being oxidized, it is desirable to place the compact in a vacuum (under reduced pressure) or in an inert gas. By placing in a vacuum (under reduced pressure), the effect that the evaporation of water can be promoted is also obtained. Further, when the molded body is heated, the drying temperature is set to 150 in order to suppress the oxidation of the magnet powder in the drying step due to the dissolved oxygen contained in water or the adsorbed oxygen adsorbed to the particles of the magnet powder. It is desirable to set the temperature below ℃. Further, the heating time is preferably short in order to suppress oxidation, but when the molded body is rapidly heated, water in the molded body may bump and the shape of the molded body may be destroyed. Considering these points, the heating time may be appropriately determined by conducting a preliminary experiment or the like. A heater, an incandescent lamp, a microwave oven or other heating device using microwaves can be used to heat the molded body.

本発明に係るボンド磁石の製造工程では上記のように、成形体から水を蒸発させることにより固化させる。そのため、製造時に有毒ガスを発生させることがなく、安全に、且つ環境に悪影響を与えることなく製造することができる。 In the manufacturing process of the bonded magnet according to the present invention, as described above, the molded body is solidified by evaporating water. Therefore, no toxic gas is generated during manufacturing, and the manufacturing can be performed safely and without adversely affecting the environment.

磁石粉末には、希土類元素("R"とする)、鉄(Fe)及び硼素(B)を主な構成元素とするRFeB系磁石(特に、Rとして主にネオジム(Nd)を有するNdFeB系磁石)の粉末、サマリウム(Sm)、鉄及び窒素(N)を主な構成元素とするSmFeN系磁石の粉末、サマリウム及びコバルト(Co)を主な構成元素とするSmCo系磁石の粉末等を用いることができる。特に、SmFeN系磁石の粉末は、NdFeB系磁石の粉末よりも水に対する耐食性が高く錆び難いため、好ましい。 The magnet powder includes RFeB-based magnets containing rare earth elements ("R"), iron (Fe) and boron (B) as main constituent elements (particularly NdFeB-based magnets containing mainly neodymium (Nd) as R). ) Powder, samarium (Sm), SmFeN magnet powder containing iron and nitrogen (N) as main constituent elements, SmCo magnet powder containing samarium and cobalt (Co) as main constituent elements, etc. You can In particular, the powder of the SmFeN-based magnet is preferable because it has higher corrosion resistance to water and is less likely to rust than the powder of the NdFeB-based magnet.

上記製造方法(以下、「第1の態様」の製造方法とする)では成形体を作製した後に該成形体から水を蒸発させるが、その代わりに、ボンド磁石材料を所定の形状に成形しながら該ボンド磁石材料から水を蒸発させること、言い換えれば、成形と水の蒸発を同時並行で行うこともできる。すなわち、本発明に係るボンド磁石の製造方法の他の態様(以下、「第2の態様」の製造方法とする)は、
セルロースナノファイバの含有率が5〜15質量%であるセルロースナノファイバ−水混合物を用意する工程と、
前記セルロースナノファイバ−水混合物と磁石粉末を、該セルロースナノファイバ−水混合物の質量と該磁石粉末の質量の合計に占める水の質量の割合が9〜28質量%となるように混合することによりボンド磁石材料を作製する工程と、
前記ボンド磁石材料を所定の形状に成形しながら該ボンド磁石材料から水を蒸発させる工程と
を有することを特徴とする。
In the above-mentioned manufacturing method (hereinafter, referred to as “manufacturing method of “first aspect”), water is evaporated from the molded body after the molded body is manufactured. Instead, the bonded magnet material is molded into a predetermined shape. It is also possible to evaporate water from the bonded magnet material, in other words, to perform molding and water evaporation in parallel. That is, another aspect of the method for producing a bonded magnet according to the present invention (hereinafter referred to as the “second aspect”) is
A step of preparing a cellulose nanofiber-water mixture having a content of cellulose nanofibers of 5 to 15% by mass,
By mixing the cellulose nanofiber-water mixture and the magnet powder so that the ratio of the mass of water to the total mass of the cellulose nanofiber-water mixture and the mass of the magnet powder is 9 to 28 mass %. A step of producing a bonded magnet material,
A step of evaporating water from the bonded magnet material while molding the bonded magnet material into a predetermined shape.

なお、ボンド磁石材料を所定の形状に成形しながら該ボンド磁石材料から水を蒸発させる工程においては、例えば磁石粉末及びセルロースナノファイバは通過せず水のみが通過するフィルタや隙間を成形型に設けておくことにより、それらフィルタや隙間から水を蒸発させることができる。その際、成形型の周囲を真空にしたり、成形型内のボンド磁石材料を加熱することにより、水の蒸発を促進させてもよい。 In addition, in the step of evaporating water from the bond magnet material while molding the bond magnet material into a predetermined shape, for example, a filter or a gap through which only water passes but not magnet powder and cellulose nanofibers is provided in the molding die. By preserving it, water can be evaporated from the filters and the gaps. At that time, the evaporation of water may be promoted by creating a vacuum around the mold or by heating the bonded magnet material in the mold.

第1及び第2の態様の製造方法において、前記ボンド磁石材料を作製した後であって前記成形体を作製する前に、前記ボンド磁石材料に含まれる水の一部を蒸発させる工程を行うことができる。これにより、ボンド磁石材料を作製する際には相対的に水の含有率が高い状態でCNF−水混合物と磁石粉末を混合するため、ボンド磁石材料内の磁石粉末が均一に近くなるように混合することができる。また、成形体を作製する際には相対的に水の含有率が低い状態で成形を行うため、成形体の形状を維持し易くなる。 In the manufacturing methods of the first and second aspects, performing a step of evaporating a part of water contained in the bond magnet material after the bond magnet material is manufactured and before the molded body is manufactured. You can This allows the CNF-water mixture and the magnet powder to be mixed in a state in which the water content is relatively high when the bonded magnet material is produced, so that the magnet powder in the bonded magnet material is mixed so as to be nearly uniform. can do. In addition, since the molding is performed in a state where the water content is relatively low, the shape of the molded body can be easily maintained.

本発明によれば、自動車用モータの使用時における温度域での耐熱性を有し、安全且つ環境に悪影響を与えることなく製造することができるボンド磁石を得ることができる。 According to the present invention, it is possible to obtain a bonded magnet that has heat resistance in a temperature range when an automobile motor is used and that can be manufactured safely and without adversely affecting the environment.

本発明に係るボンド磁石製造方法((a)〜(f))及びボンド磁石((g))の一実施形態を示す概略図。Schematic which shows one Embodiment of the bonded magnet manufacturing method ((a)-(f)) and bonded magnet ((g)) which concern on this invention. 本実施形態のボンド磁石の一例につき、(a)上面及び(b)側面の外見を示す写真。The photograph which shows the appearance of (a) upper surface and (b) side surface about an example of the bonded magnet of this embodiment. 本実施形態のボンド磁石の実施例及び従来のボンド磁石につき、室温における磁石密度及び最大エネルギー積(BH)maxを測定した結果を示すグラフ。The graph which shows the result of having measured the magnet density and maximum energy product (BH) max in room temperature about the example of the bonded magnet of this embodiment, and the conventional bonded magnet. 実施例のボンド磁石につき、室温から180℃までの温度範囲で残留磁束密度Brを測定した結果を示すグラフ。Per bonded magnets of Examples, a graph showing the results of measuring the residual magnetic flux density B r in a temperature range up to 180 ° C. from room temperature. 実施例のボンド磁石につき、室温から180℃までの温度範囲で保磁力HcJを測定した結果を示すグラフ。The graph which shows the result of having measured the coercive force HcJ in the temperature range from room temperature to 180 degreeC about the bonded magnet of an Example.

図1〜図5を用いて、本発明に係るボンド磁石及びその製造方法の実施形態を説明する。 Embodiments of a bonded magnet and a method for manufacturing the same according to the present invention will be described with reference to FIGS.

まず、図1を用いて、本発明に係る第1の態様のボンド磁石の製造方法につき、その実施形態を説明する。初めに、CNF−水混合物11を用意する(図1(a))。CNF−水混合物11は、株式会社スギノマシーンにより「BiNFi-s」(登録商標)との商品名で販売されている。CNF−水混合物11におけるCNFの含有率は、5〜15質量%の範囲内となるようにする。例えば、上記「BiNFi-s」では規格品として、CNFの含有率が5質量%及び10質量%のものが販売されており、それらを本実施形態のCNF−水混合物11として用いることができる。また、規格品を加熱して水の一部を蒸発させることにより、これら規格品よりもCNFの含有率が高いCNF−水混合物11を得ることができる。ここでCNF−水混合物11中のCNFの含有率が小さすぎると後述の成形体14の形状を維持し難くなる。一方、該含有率が大きすぎると、成形体14があまり収縮しないことから密度が高くならなかったり、成形体14に亀裂が生じ易くなるという問題が生じるうえに、磁気特性が低下する。そのため、CNFの含有率は5〜15質量%の範囲内とする。なお、CNFの含有率が5質量%よりも小さい場合には、フィルター等を用いて脱水することにより、CNFの含有率を5〜15質量%の範囲内となるように調整しても良い。また、CNFの含有率が15質量%よりも大きい場合には、水を添加することにより、CNFの含有率を5〜15質量%の範囲内となるように調整しても良い。 First, an embodiment of a method for manufacturing a bonded magnet according to a first aspect of the present invention will be described with reference to FIG. First, a CNF-water mixture 11 is prepared (FIG. 1(a)). The CNF-water mixture 11 is sold by Sugino Machine Limited under the trade name "BiNFi-s" (registered trademark). The content of CNF in the CNF-water mixture 11 should be in the range of 5 to 15% by mass. For example, in the above-mentioned “BiNFi-s”, as standard products, CNF contents of 5% by mass and 10% by mass are sold, and these can be used as the CNF-water mixture 11 of the present embodiment. Further, by heating the standard product to evaporate part of the water, the CNF-water mixture 11 having a higher CNF content than these standard products can be obtained. If the CNF content in the CNF-water mixture 11 is too low, it will be difficult to maintain the shape of the molded body 14 described below. On the other hand, if the content is too large, the molded body 14 does not shrink so much that the density does not increase, cracks are likely to occur in the molded body 14, and the magnetic properties deteriorate. Therefore, the content ratio of CNF is set within the range of 5 to 15% by mass. When the content of CNF is less than 5% by mass, the content of CNF may be adjusted to be in the range of 5 to 15% by dehydration using a filter or the like. When the CNF content is higher than 15% by mass, water may be added to adjust the CNF content to be in the range of 5 to 15% by mass.

それと共に、磁石粉末12を用意する。磁石粉末12には、RFeB系磁石の粉末、SmFeN系磁石の粉末、SmCo系磁石の粉末等を用いることができる。その中でSmFeN系磁石の粉末は、酸化し難く、且つFeよりも高価なCoを使用する必要がないという点で優れている。磁石粉末12の作製方法は、従来のボンド磁石を製造する際に用いられている方法と同じであるため、説明を省略する。 At the same time, magnet powder 12 is prepared. As the magnet powder 12, RFeB-based magnet powder, SmFeN-based magnet powder, SmCo-based magnet powder, or the like can be used. Among them, the powder of the SmFeN magnet is excellent in that it is difficult to oxidize and it is not necessary to use Co which is more expensive than Fe. The method for producing the magnet powder 12 is the same as the method used for producing a conventional bonded magnet, and thus the description thereof is omitted.

次に、CNF−水混合物11と磁石粉末12を、両者の質量の合計に占める水の質量の割合(ボンド磁石材料13の含水率)が9〜28質量%の範囲内となるように混合する(図1(b))ことにより、ボンド磁石材料13を作製する(同(c))。ボンド磁石材料13は、CNF−水混合物11中のCNFの含有率を上記範囲内にすると共に、該ボンド磁石材料13の含水率を上記範囲内にすることにより、次に述べる成形体14の形状を維持することができる程度の適度な粘性を有する流動体となる。 Next, the CNF-water mixture 11 and the magnet powder 12 are mixed so that the ratio of the mass of water to the total mass of the both (water content of the bonded magnet material 13) is in the range of 9 to 28 mass %. The bonded magnet material 13 is produced by (FIG. 1(b)) (FIG. 1(c)). The bonded magnet material 13 has a CNF content in the CNF-water mixture 11 within the above range, and the bonded magnet material 13 has a water content within the above range, whereby the shape of the molded body 14 described below is obtained. The fluid has an appropriate viscosity to the extent that it can be maintained.

次に、ボンド磁石材料13を成形する(図1(d))ことにより成形体14を作製する(同(e))。ボンド磁石材料13の成形には、圧縮成形や射出成形の手法を用いることができる。圧縮成形では、図1(d)に示すように、ボンド磁石材料13をモールド131に充填したうえで、プレス機(図示せず)を用いてパンチ132によってボンド磁石材料13に圧力を印加することにより、成形体14を作製することができる。圧縮成形時の圧力は、本実施形態では2〜20tonf/cm2(約0.2〜2GPa)としたが、この範囲には限定されない。射出成形では、例えば二軸混練押出器によりCNF−水混合物11と磁石粉末12を混練したうえでモールド内に押し出すことにより、成形体14を作製することができる。 Next, the molded body 14 is manufactured by molding the bonded magnet material 13 (FIG. 1D) (FIG. 1E). A method such as compression molding or injection molding can be used for molding the bonded magnet material 13. In the compression molding, as shown in FIG. 1D, after the bond magnet material 13 is filled in the mold 131, a pressure is applied to the bond magnet material 13 by the punch 132 using a press machine (not shown). Thus, the molded body 14 can be manufactured. The pressure during compression molding is 2 to 20 tonf/cm 2 (about 0.2 to 2 GPa) in this embodiment, but the pressure is not limited to this range. In injection molding, the molded body 14 can be produced by, for example, kneading the CNF-water mixture 11 and the magnet powder 12 with a biaxial kneading extruder and extruding the mixture into the mold.

次に、得られた成形体14から水を蒸発させる(図1(f))。その際、成形体14を常温に維持したままにしてもよいし、成形体14を加熱してもよい。成形体14を加熱する場合には、温度を150℃以下とすることが望ましい。また、加熱の有無に依らず、成形体14は真空中(減圧下)又は不活性ガス中に置くことが望ましい。 Next, water is evaporated from the obtained molded body 14 (FIG. 1(f)). At this time, the molded body 14 may be kept at room temperature, or the molded body 14 may be heated. When the molded body 14 is heated, it is desirable that the temperature be 150° C. or lower. Further, it is desirable that the molded body 14 is placed in a vacuum (under reduced pressure) or in an inert gas regardless of whether or not it is heated.

以上の操作により、本発明に係るボンド磁石20が得られる(図1(g))。本発明に係るボンド磁石20は、磁石粉末と、該磁石粉末の粒子21同士を結合するCNFから成るバインダ22とを備える。ボンド磁石20の磁石粉末に含まれる磁石の種類は、上述した製造時に用いる原料のものと同じである。 By the above operation, the bonded magnet 20 according to the present invention is obtained (FIG. 1(g)). The bonded magnet 20 according to the present invention includes magnet powder and a binder 22 made of CNF that bonds the particles 21 of the magnet powder. The type of magnet contained in the magnet powder of the bonded magnet 20 is the same as that of the raw material used in the above-described manufacturing.

上記実施形態の製造方法では成形体14を作製した後に該成形体14から水を蒸発させたが、ボンド磁石材料13を成形しながら水を蒸発させるようにしてもよい。その際、例えばモールド131とパンチ132の間に、磁石粉末及びセルロースナノファイバは通過せず水のみが通過する隙間を設けたり、モールド131の一部に、磁石粉末及びセルロースナノファイバは通過せず水のみが通過する大きさの目を有するフィルタを設けること等により、成形体14から蒸発する水をモールド131の外に排出することができる。また、モールド131の周囲を真空にしたり、モールド131内の成形体14を加熱することにより、成形体14からの水の蒸発を促進させてもよい。 In the manufacturing method of the above-described embodiment, the water is evaporated from the molded body 14 after the molded body 14 is manufactured, but the water may be evaporated while the bonded magnet material 13 is molded. At that time, for example, a gap is provided between the mold 131 and the punch 132, through which the magnet powder and the cellulose nanofibers do not pass, and only water passes, or a part of the mold 131 does not pass the magnet powder and the cellulose nanofibers. The water evaporated from the molded body 14 can be discharged to the outside of the mold 131 by providing a filter having a size that allows only water to pass through. Further, the evaporation of water from the molded body 14 may be promoted by creating a vacuum around the mold 131 or by heating the molded body 14 in the mold 131.

次に、本発明に係るボンド磁石を作製したうえで磁気特性を測定した実験の結果を説明する。 Next, the results of an experiment in which the magnetic characteristics of the bonded magnet according to the present invention were measured will be described.

(1) 実験1
この実験では、CNF−水混合物11中のCNFの含有率は10質量%とした。磁石粉末12にはSmFeN系磁石(実施例1〜11)又はNdFeB系磁石(実施例12)の粉末を用いた。SmFeN系磁石の磁石粉末12の作製方法は以下の通りである。まず、Sm:19.3質量%、Zr:1.7質量%、Co:4.0質量%、N:3.3質量%、Fe:残部となるように、Nを除く各元素を含有する合金を溶解し、得られた溶湯を、単ロール超急冷装置を用いてロール上に落下させて急冷するとによりリボン状のフレーク粉を作製した。このフレーク粉をピンミルで粉砕し、目開き53μmの篩を用いて分級する。その後、窒素原子を有する分子を含むガス(この例ではアンモニアと水素の混合ガス)中で加熱することで窒化させることにより、SmFeN系磁石の磁石粉末12が得られた。NdFeB系磁石の磁石粉末12の作製方法は、原料の合金の組成が異なる(Nd:24.8質量%、Pr:0.84質量%、B:0.92質量%、Fe:残部)点と、窒素原子を有する分子を含むガス中での加熱を行わない点を除いて、SmFeN系磁石の磁石粉末12の作製方法と同様である。
(1) Experiment 1
In this experiment, the content of CNF in the CNF-water mixture 11 was 10% by mass. As the magnet powder 12, powder of SmFeN magnet (Examples 1 to 11) or NdFeB magnet (Example 12) was used. The method for producing the magnet powder 12 of the SmFeN magnet is as follows. First, Sm: 19.3% by mass, Zr: 1.7% by mass, Co: 4.0% by mass, N: 3.3% by mass, Fe: The alloy containing each element except N was obtained by melting so as to be the balance, and obtained. A ribbon-shaped flake powder was produced by dropping the molten metal onto a roll using a single-roll ultra-quenching device and quenching. The flake powder is crushed with a pin mill and classified with a sieve having an opening of 53 μm. Then, by heating in a gas containing a molecule having a nitrogen atom (a mixed gas of ammonia and hydrogen in this example) to perform nitriding, the magnet powder 12 of the SmFeN magnet was obtained. The method for producing the magnet powder 12 of the NdFeB-based magnet is different in the composition of the raw material alloy (Nd: 24.8 mass %, Pr: 0.84 mass %, B: 0.92 mass %, Fe: balance), and a molecule having a nitrogen atom. The method is the same as the method for producing the magnet powder 12 of the SmFeN-based magnet, except that heating is not performed in a gas containing

ボンド磁石材料13における磁石粉末12の含有率は、67質量%〜91質量%の範囲内とした(後掲の表1参照)。比較例として、磁石粉末12としてSmFeN系磁石の粉末を用い、含有率が50質量%である試料の作製を試みた。 The content of the magnet powder 12 in the bonded magnet material 13 was set within the range of 67% by mass to 91% by mass (see Table 1 below). As a comparative example, an SmFeN magnet powder was used as the magnet powder 12, and an attempt was made to prepare a sample having a content rate of 50 mass %.

成形体14は、圧縮成形により作製した。圧縮成形時の圧力は2〜20tonf/cm2(約0.2〜2GPa)の範囲内とした(後掲の表1参照)。なお、ボンド磁石材料13に一度に12tonf/cm2(約1.2GPa)を超える圧力を印加すると、圧縮によってボンド磁石材料13から生じる水をモールド131から十分に排出することができないため、成形不良を生じてしまう。そのため、圧縮成形時の圧力が12tonf/cm2を超える場合には、まず、12tonf/cm2以下の圧力で仮成形を行い、それによってボンド磁石材料13から生じる水をモールド131から排出した後に、12tonf/cm2を超える圧力で本成形を行った。 The molded body 14 was produced by compression molding. The pressure during compression molding was set within the range of 2 to 20 tonf/cm 2 (about 0.2 to 2 GPa) (see Table 1 below). If a pressure exceeding 12 tonf/cm 2 (about 1.2 GPa) is applied to the bonded magnet material 13 at one time, the water generated from the bonded magnet material 13 due to compression cannot be sufficiently discharged from the mold 131, resulting in molding failure. Will occur. Therefore, when the pressure at the time of compression molding exceeds 12 tonf/cm 2 , first, temporary molding is performed at a pressure of 12 tonf/cm 2 or less, and thereby water generated from the bonded magnet material 13 is discharged from the mold 131, The main molding was performed at a pressure exceeding 12 tonf/cm 2 .

図2に、作製したボンド磁石の一例の写真を示す。作製したボンド磁石は円筒形であり(a)上面を、(b)は側面を、それぞれ示している。作製したボンド磁石は外見上、通常のボンド磁石と何らの相違も見られない。 FIG. 2 shows a photograph of an example of the produced bonded magnet. The produced bonded magnet has a cylindrical shape, (a) shows the upper surface, and (b) shows the side surface. The produced bond magnet does not seem to be different from a normal bond magnet in appearance.

作製した各実施例及び比較例の試料につき、ボンド磁石材料13中の磁石粉末12の含有率、圧縮成形時の圧力、成形状態(後述)、ボンド磁石20の密度、及び室温での磁気特性を表1に示す。ここで成形状態は、圧縮成形により所定の形状の成形体14が得られたものを「○」、モールド131から取り出したときに成形体14がわずかに変形したものを「△」、モールド131から取り出したときに形状を保つことができず成形体14を(従って、ボンド磁石20も)得ることができなかったものを「×」とした。磁気特性は、成形状態が「○」及び「△」である試料を対象として、残留磁束密度Br、保磁力HcJ、最大エネルギー積(BH)maxを測定した。
For each of the manufactured samples of Examples and Comparative Examples, the content of the magnet powder 12 in the bonded magnet material 13, the pressure during compression molding, the molding state (described later), the density of the bond magnet 20, and the magnetic characteristics at room temperature were measured. It shows in Table 1. Here, the molding state is “◯” when the molded body 14 having a predetermined shape is obtained by compression molding, “Δ” when the molded body 14 is slightly deformed when taken out from the mold 131, and from the mold 131. The case where the shape could not be maintained and the molded body 14 (and hence the bonded magnet 20) could not be obtained when taken out was designated as "x". Regarding the magnetic properties, the residual magnetic flux density B r , the coercive force H cJ , and the maximum energy product (BH) max were measured for the samples whose molding states were “◯” and “Δ”.

各実施例の試料では、成形状態が○(実施例2〜12)又は△(実施例1)であり、ボンド磁石20を得ることができた。それに対して比較例では、ボンド磁石材料13が圧縮成形後も柔らかく、成形型を外す際に形状を維持することができなかった。 In the samples of each example, the molding state was ◯ (Examples 2 to 12) or Δ (Example 1), and the bonded magnet 20 could be obtained. On the other hand, in the comparative example, the bonded magnet material 13 was soft even after compression molding, and the shape could not be maintained when the mold was removed.

図3に、実施例1〜11(SmFeN系ボンド磁石)の室温での磁気特性のうち最大エネルギー積(BH)maxについて、磁石密度との関係をグラフで示す。グラフ中の菱形の点が各実施例の測定結果を示している。このグラフには併せて、バインダとしてエポキシ樹脂を用い、16又は20tonf/cm2(約1.6又は2GPa)の圧力を印加しつつアルゴンガス中において温度170℃で1時間加熱することにより硬化させた、従来のSmFeN系ボンド磁石の磁石密度と最大エネルギー積(BH)maxの関係を測定したデータを丸印(図3中に「従来」と記載)で示す。磁石密度と最大エネルギー積(BH)maxには一次関数で表される関係がある。本発明の各実施例と従来のSmFeN系ボンド磁石のデータは同じ一次関数で近似することができる。このことは、本発明の各実施例のSmFeN系ボンド磁石が従来のSmFeN系ボンド磁石と同等の最大エネルギー積(BH)maxを有することを意味している。 FIG. 3 is a graph showing the relationship between the maximum energy product (BH) max of the magnetic properties of Examples 1 to 11 (SmFeN-based bonded magnets) at room temperature and the magnet density. The diamond points in the graph show the measurement results of each example. In addition to this graph, epoxy resin was used as a binder, and cured by heating at a temperature of 170° C. for 1 hour in argon gas while applying a pressure of 16 or 20 tonf/cm 2 (about 1.6 or 2 GPa), The data obtained by measuring the relationship between the magnet density and the maximum energy product (BH) max of the conventional SmFeN-based bonded magnet are shown by circles (indicated as “conventional” in FIG. 3). There is a relation expressed by a linear function between the magnet density and the maximum energy product (BH) max . The data of each example of the present invention and the conventional SmFeN-based bonded magnet can be approximated by the same linear function. This means that the SmFeN-based bonded magnets of the respective examples of the present invention have a maximum energy product (BH) max equivalent to that of the conventional SmFeN-based bonded magnet.

次に、実施例4の試料につき、室温から180℃まで温度を上昇させる実験を行った。この試料は、温度が180℃に達しても、バインダが溶解することなく形状を維持することができた。この試料につき、室温から180℃までの温度範囲で残留磁束密度Br及び保磁力HcJを測定した。残留磁束密度Brの測定結果を図4に、保磁力HcJの測定結果を図5に、それぞれ示す。残留磁束密度Br及び保磁力HcJは共に、温度の上昇に伴って低下するものの、180℃において残留磁束密度Brが5.4kG、保磁力HcJが4.7kOeという値が得られる。 Next, an experiment was conducted on the sample of Example 4 to raise the temperature from room temperature to 180°C. This sample was able to maintain its shape without melting the binder even when the temperature reached 180°C. With respect to this sample, the residual magnetic flux density B r and the coercive force H cJ were measured in the temperature range from room temperature to 180°C. The measurement result of the residual magnetic flux density B r is shown in FIG. 4, and the measurement result of the coercive force H cJ is shown in FIG. 5, respectively. Both the residual magnetic flux density B r and the coercive force H cJ decrease with increasing temperature, but at 180° C., the residual magnetic flux density B r is 5.4 kG and the coercive force H cJ is 4.7 kOe.

(2) 実験2
この実験では、CNFの含有率が5質量%、10質量%及び15質量%である3種類のCNF−水混合物11を用いた。これら3種類のCNF−水混合物11についてそれぞれ、実験1で用いたSmFeN系磁石の粉末と同じ組成を有する磁石粉末12とCNF−水混合物11の配合比が質量比で10/1(磁石粉末12が90.9質量%)、10/1.5(同87.0質量%)、10/2(同83.3質量%)、10/2.5(同80.0質量%)、10/3(同76.9質量%)、10/3.5(同74.1質量%)、10/4(同71.4質量%)、10/4.5(同69.0質量%)、10/5(同66.7質量%)及び10/10(同50.0質量%)という異なる複数種のボンド磁石材料13を作製した。それらのボンド磁石材料13につき、含水率、及び12.0tonf/cm2(約1.2GPa)の圧力で圧縮成形した成形体14の成形状態を表2に示す。ここで成形状態の評価基準は、実験1と同様である。
(2) Experiment 2
In this experiment, three kinds of CNF-water mixtures 11 having CNF contents of 5% by mass, 10% by mass and 15% by mass were used. For each of these three types of CNF-water mixture 11, the compounding ratio of the magnet powder 12 having the same composition as the powder of the SmFeN magnet used in Experiment 1 and the CNF-water mixture 11 was 10/1 (magnet powder 12 Is 90.9 mass%), 10/1.5 (87.0 mass% of the same), 10/2 (83.3 mass% of the same), 10/2.5 (80.0 mass% of the same), 10/3 (76.9 mass% of the same), 10/3.5 ( 74.1% by mass, 10/4 (71.4% by mass), 10/4.5 (69.0% by mass), 10/5 (66.7% by mass) and 10/10 (50.0% by mass) A bonded magnet material 13 was produced. Table 2 shows the water content and the molding state of the molded body 14 compression-molded at a pressure of 12.0 tonf/cm 2 (about 1.2 GPa) for these bonded magnet materials 13. Here, the evaluation criteria of the molding state are the same as in Experiment 1.

この実験結果より、CNF−水混合物11中のCNFの含有率が5〜15質量%の範囲内では、当該含有率に依らずに、ボンド磁石材料13の含水率が9〜28質量%の範囲内にあるときに、成形状態が○又は△、すなわち成形体14が得られることがわかる。成形体14が得られれた例におけるボンド磁石20中のCNFの含有率(CNFの質量を、CNFの質量と磁石粉末12の質量の和で除した値)は、磁石粉末12とCNF−水混合物11の配合比が10/1、CNF−水混合物11におけるCNFの含有率が5質量%のときに最小である0.5質量%(1×0.05/(10+1×0.05))となり、前者が10/5、後者が15質量%のときに最大である7質量%(5×0.15/(10+5×0.15))となる。 From this experimental result, when the content of CNF in the CNF-water mixture 11 is in the range of 5 to 15 mass %, the water content of the bonded magnet material 13 is in the range of 9 to 28 mass% regardless of the content. It can be seen that the molding state is ◯ or Δ, that is, the molded body 14 is obtained when it is inside. The content ratio of CNF in the bonded magnet 20 (the value obtained by dividing the mass of CNF by the sum of the mass of CNF and the mass of the magnet powder 12) in the example in which the molded body 14 was obtained is the magnet powder 12 and the CNF-water mixture. When the compounding ratio of 11 is 10/1 and the content of CNF in the CNF-water mixture 11 is 5% by mass, the minimum is 0.5% by mass (1×0.05/(10+1×0.05)), and the former is 10%. /5, the maximum is 7% by mass (5×0.15/(10+5×0.15)) when the latter is 15% by mass.

本発明は上記実施形態・実施例に限定されず、種々の変形が可能である。 The present invention is not limited to the above embodiments and examples, and various modifications can be made.

11…CNF−水混合物
12…磁石粉末
13…ボンド磁石材料
131…モールド
132…パンチ
14…成形体
20…ボンド磁石
21…磁石粉末の粒子
22…バインダ
11... CNF-water mixture 12... Magnet powder 13... Bond magnet material 131... Mold 132... Punch 14... Molded body 20... Bond magnet 21... Magnet powder particles 22... Binder

Claims (6)

磁石粉末と、
該磁石粉末の粒子同士を結合する、セルロースナノファイバから成るバインダと
を備えることを特徴とするボンド磁石。
Magnet powder,
A bonded magnet comprising a binder made of cellulose nanofibers, which binds particles of the magnet powder to each other.
前記磁石粉末がSmFeN系磁石の粉末の粉末であることを特徴とする請求項1に記載のボンド磁石。 The bonded magnet according to claim 1, wherein the magnet powder is a powder of SmFeN magnet. セルロースナノファイバの含有率が0.5〜7質量%であることを特徴とする請求項1又は2に記載のボンド磁石。 The bonded magnet according to claim 1 or 2, wherein the content of the cellulose nanofibers is 0.5 to 7% by mass. セルロースナノファイバの含有率が5〜15質量%であるセルロースナノファイバ−水混合物を用意する工程と、
前記セルロースナノファイバ−水混合物と磁石粉末を、該セルロースナノファイバ−水混合物の質量と該磁石粉末の質量の合計に占める水の質量の割合が9〜28質量%となるように混合することによりボンド磁石材料を作製する工程と、
前記ボンド磁石材料を所定の形状に成形することにより成形体を作製する工程と、
前記成形体から水を蒸発させることによりボンド磁石を作製する工程と
を有することを特徴とするボンド磁石の製造方法。
A step of preparing a cellulose nanofiber-water mixture having a content of cellulose nanofibers of 5 to 15% by mass,
By mixing the cellulose nanofiber-water mixture and the magnet powder so that the ratio of the mass of water to the total mass of the cellulose nanofiber-water mixture and the mass of the magnet powder is 9 to 28 mass %. A step of producing a bonded magnet material,
A step of producing a molded body by molding the bonded magnet material into a predetermined shape,
And a step of producing a bonded magnet by evaporating water from the molded body.
セルロースナノファイバの含有率が5〜15質量%であるセルロースナノファイバ−水混合物を用意する工程と、
前記セルロースナノファイバ−水混合物と磁石粉末を、該セルロースナノファイバ−水混合物の質量と該磁石粉末の質量の合計に占める水の質量の割合が9〜28質量%となるように混合することによりボンド磁石材料を作製する工程と、
前記ボンド磁石材料を所定の形状に成形しながら該ボンド磁石材料から水を蒸発させる工程と
を有することを特徴とするボンド磁石の製造方法。
A step of preparing a cellulose nanofiber-water mixture having a content of cellulose nanofibers of 5 to 15% by mass,
By mixing the cellulose nanofiber-water mixture and the magnet powder so that the ratio of the mass of water to the total mass of the cellulose nanofiber-water mixture and the mass of the magnet powder is 9 to 28 mass %. A step of producing a bonded magnet material,
A step of evaporating water from the bonded magnet material while molding the bonded magnet material into a predetermined shape.
前記磁石粉末がSmFeN系磁石の粉末の粉末であることを特徴とする請求項4又は5に記載のボンド磁石の製造方法。 The method for producing a bonded magnet according to claim 4 or 5, wherein the magnet powder is a powder of SmFeN-based magnet powder.
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