JP3142324B2 - Manufacturing method of metal magnetic powder - Google Patents

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は高密度磁気記録媒体用の
磁性粉として用いられる、保磁力が高く、保磁力分布が
シャープであり、分散性に優れ、且つ酸化安定性に優れ
る金属磁性粉末の製造法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal powder having a high coercive force, a sharp coercive force distribution, excellent dispersibility, and excellent oxidation stability, which is used as a magnetic powder for a high density magnetic recording medium. The method relates to a method for producing the same.

【０００２】[0002]

【従来の技術】高密度磁気記録媒体用の磁性粉として、
鉄を主成分とする金属磁性粉末の開発が進められ、オー
ディオテープ、ビデオ用テープ、フロッピーディスクと
して実用化されている。金属磁性粉末の現在実用化され
ている一般的な製造法は、鉄を主体とする針状のオキシ
水酸化鉄あるいは酸化鉄を還元性ガス中で加熱還元し
て、金属あるいは合金の粉末とした後、粒子表面に薄い
酸化皮膜を形成させる方法である。近年、磁気記録再生
装置の小型軽量化、高画質化、長時間化が進められ、そ
れに伴い使用する磁気記録媒体の高密度化が強く要望さ
れている。磁気記録媒体の高密度化を達成するために
は、使用する金属磁性粉末が、微細粒子であり、保磁力
が高く、飽和磁束密度が大きく、且つ分散性に優れ、酸
化安定性にも優れる必要がある。2. Description of the Related Art As magnetic powder for high-density magnetic recording media,
Development of metal magnetic powders containing iron as a main component has been promoted, and has been put to practical use as audio tapes, video tapes, and floppy disks. The general production method of metal magnetic powder that is currently in practical use is a method of heating and reducing needle-shaped iron oxyhydroxide or iron oxide mainly composed of iron in a reducing gas to obtain a metal or alloy powder. Then, a thin oxide film is formed on the particle surface. In recent years, the size and weight of magnetic recording / reproducing devices have been reduced, the image quality has been increased, and the length of time has been increased. Accordingly, there has been a strong demand for higher density of magnetic recording media to be used. In order to achieve high density of magnetic recording media, the metal magnetic powder used must be fine particles, have high coercive force, high saturation magnetic flux density, excellent dispersibility, and excellent oxidation stability. There is.

【０００３】金属磁性粉末の保磁力は、金属の組成が一
定であるならば、針状粒子の大きさに最も影響される。
一般論として、粒子の太さが一定であれば、針状粒子の
軸比（粒子の長さ／太さ）が大であるほど保磁力は高く
なる。しかるに、最近の高密度化に伴う、より短波長で
の記録再生の必要性から、金属磁性粉末粒子の長さはよ
り短いものが要望され、また磁気記録再生ヘッドの改良
が進められて、保磁力が高いものでも使用できるように
なり、より保磁力の高いものが強く要望されている。粒
子が短いものでも、粒子の太さがより小さくなり、軸比
が大に出来るならば、保磁力を高くすることが可能であ
るが、粒子の太さを小さくすることには限界がある。こ
の理由は、一つには粒子があまり細くなると、超常磁性
が発現して保磁力を示さないことであり、二つめには金
属磁性粉末には大気中で安全に取り扱えるようにするた
めに粒子の表面に酸化皮膜が形成されており、粒子があ
まり細かくなると酸化皮膜ばかりになり、磁性を示さな
くなってしまうからである。したがって微細粒子は必然
的に軸比の小さい粒子になり、保磁力を高くすることは
難しい傾向がある。飽和磁束密度は金属磁性粉末の組
成、粒子の大きさ、酸化皮膜の厚さにより変化する。組
成としては、鉄を主体とした合金を考えた場合、コバル
トの添加が有効である。粒子の大きさでは粒子が大きい
程、粒子表面の酸化皮膜の厚さが同じもの同士を比較す
ると、酸化皮膜の量と金属部分の割合において、金属部
分の割合が大きくなり、飽和磁束密度も当然のことなが
ら大きくなる。粒子体積が同じものを比較すると、酸化
皮膜の厚さが同じものでは、軸比の小さい方が表面積も
小さく、酸化皮膜の割合が小さくなり、飽和磁束密度は
大きくなる。しかし、軸比は保磁力に大きく影響するの
で、極端に小さくはできない。酸化皮膜を薄くすること
により、金属磁性粉末の飽和磁束密度は大きくはなる
が、大気中で安全に取り扱うこと、また磁気記録媒体と
した時の経時安定性を考えた場合、酸化皮膜を薄くする
ことは好ましくない。金属磁性粉末の分散性は、粒子の
形状、および表面の化学的性質が大きく影響し、媒体に
使用する樹脂との相性もあるが、一般論として、粒子が
微細になるほど分散は難しくなる方向である。金属磁性
粉末の酸化安定性（高温、高湿下でのσs の経時変化）
は、酸化皮膜の緻密さや粒子表面に被覆する形状保持剤
の種類によって変化するが、粒子が微細になり、表面積
が大きくなることにより、σs の経時変化が大きくな
り、酸化安定性は悪くなる傾向がある。[0003] The coercive force of a metal magnetic powder is most affected by the size of the acicular particles if the composition of the metal is constant.
As a general theory, if the thickness of the particles is constant, the coercive force increases as the axial ratio (length / thickness of the particles) of the acicular particles increases. However, due to the recent need for recording and reproducing at shorter wavelengths due to higher densities, shorter magnetic metal powder particles have been required, and improvements in magnetic recording and reproducing heads have been promoted. Materials having high magnetic force can be used, and materials having higher coercive force are strongly desired. Even if the particles are short, it is possible to increase the coercive force if the particle thickness becomes smaller and the axial ratio can be increased, but there is a limit to reducing the particle thickness. One reason is that if the particles become too thin, superparamagnetism will be exhibited and no coercive force will be exhibited.Secondly, metal magnetic powders will be used to ensure safe handling in air. This is because an oxide film is formed on the surface of the film, and if the particles become too fine, only the oxide film is formed, and the particles no longer show magnetism. Therefore, the fine particles necessarily have a small axial ratio, and it tends to be difficult to increase the coercive force. The saturation magnetic flux density changes depending on the composition of the metal magnetic powder, the size of the particles, and the thickness of the oxide film. When considering an alloy mainly composed of iron, the addition of cobalt is effective. As for the size of the particles, the larger the particles, the greater the thickness of the oxide film on the surface of the particles, the greater the ratio of the metal portion in the amount of the oxide film and the ratio of the metal portion. It gets bigger. Comparing particles having the same particle volume, when the thickness of the oxide film is the same, the smaller the axial ratio, the smaller the surface area, the smaller the ratio of the oxide film, and the higher the saturation magnetic flux density. However, since the axial ratio greatly affects the coercive force, it cannot be made extremely small. By making the oxide film thinner, the saturation magnetic flux density of the metal magnetic powder increases, but in consideration of safe handling in the air and stability over time when used as a magnetic recording medium, make the oxide film thinner. It is not preferable. The dispersibility of the metal magnetic powder is greatly affected by the shape of the particles and the chemical properties of the surface, and is compatible with the resin used for the medium.However, in general, the finer the particles, the more difficult it is to disperse. is there. Oxidation stability of metal magnetic powder (change of σs with time under high temperature and high humidity)
Varies depending on the density of the oxide film and the type of shape-retaining agent that covers the particle surface.However, as the particles become finer and the surface area increases, the change over time in σs increases, and the oxidation stability tends to deteriorate. There is.

【０００４】[0004]

【発明が解決しようとする課題】近年の磁気記録再生装
置の高性能化に伴い、使用する磁気記録媒体の高出力
化、低ノイズ化の要望が強く、使用する金属磁性粉末
も、微細で、保磁力が高く、飽和磁束密度の大きいもの
が望まれている。しかしながら、従来の技術では、上述
の事情によりこれらの項目を全て満足するような金属磁
性粉末は得られない。本発明はこの問題を解決すること
を目的としたものである。With the recent increase in the performance of magnetic recording / reproducing devices, there is a strong demand for higher output and lower noise of the magnetic recording medium to be used. What has a high coercive force and a large saturation magnetic flux density is desired. However, according to the conventional technique, a metal magnetic powder satisfying all of these items cannot be obtained due to the above-described circumstances. The present invention aims to solve this problem.

【０００５】[0005]

【課題を解決するための手段】本発明者等はこの問題を
解決するために種々の検討を行った結果、第一鉄塩とア
ルカリを混合した水懸濁液に、酸化性ガスを吹き込むこ
とによって得られたオキシ水酸化鉄を主体とする種結晶
の粒子表面に、酸化反応終了後、または酸化反応途中に
おいて、該懸濁液に非酸化性雰囲気下、酸化反応終了後
の場合には懸濁液に第一鉄塩水溶液及び稀土類元素化合
物および／またはケイ素化合物の水溶液を加えた後、酸
化反応途中の場合には稀土類元素化合物および／または
ケイ素化合物の水溶液を加え、酸化反応温度以上の温度
で熟成後、再び酸化性ガスを吹き込んでオキシ水酸化鉄
結晶を成長させた後、該オキシ水酸化鉄の表面に形状保
持剤を被覆し、次いで、非還元性雰囲気下、 500〜800
℃の温度で加熱処理し、しかる後、還元性ガスで加熱還
元することにより、前記の問題が解決できることを見出
し、本発明を完成するに到った。The present inventors have conducted various studies to solve this problem, and found that an oxidizing gas was blown into an aqueous suspension containing a ferrous salt and an alkali. After the oxidation reaction is completed or during the oxidation reaction, the suspension is placed under a non-oxidizing atmosphere under the non-oxidizing atmosphere, and the suspension is suspended on the particle surface of the seed crystal mainly composed of iron oxyhydroxide obtained as described above. After adding an aqueous solution of a ferrous salt and an aqueous solution of a rare earth element compound and / or a silicon compound to the suspension, add an aqueous solution of the rare earth element compound and / or a silicon compound when the oxidation reaction is in progress, and add the aqueous solution at an oxidation reaction temperature or higher. After aging at a temperature of, an oxidizing gas is blown again to grow iron oxyhydroxide crystals, and then the surface of the iron oxyhydroxide is coated with a shape-retaining agent.
It has been found that the above-mentioned problem can be solved by performing a heat treatment at a temperature of ° C. and then reducing by heating with a reducing gas, thereby completing the present invention.

【０００６】本発明において使用される第一鉄塩として
は、塩化第一鉄、硫酸第一鉄、硝酸第一鉄が使用でき
る。またアルカリとしては、水酸化ナトリウム、水酸化
カリウム等の水酸化アルカリ、炭酸ナトリウム、炭酸ア
ンモニウム等の炭酸アルカリ、アンモニア等が使用でき
る。また、酸化性ガスとしては、酸素ガス、空気等の公
知のガスが使用できる。このようにして得られるオキシ
水酸化鉄としては、α−FeOOH 、β−FeOOH 、γ−FeOO
H 等があげられ、特にα−FeOOH 、γ−FeOOH が好まし
い。なお、該オキシ水酸化鉄の形状は、長軸長が0.05〜
0.3 μm 、軸比が３〜15の、針状、柱状、紡錘状、棒状
のものが好ましく、粒子中にCo，Ni，Cr，Mn，Mg，Ca，
Ba，Sr，Zn，Ti，Mo，Ag，Cu等の金属化合物が含まれる
場合にも有効である。本発明で使用される稀土類元素は
La，Ce，Pr，Nd，Sm，Gd，Dy，Y のうち少なくとも１種
類であり、これらの組合せでも有効である。添加量はオ
キシ水酸化鉄中の鉄に対して 0.3〜10wt％が好ましく、
0.5〜5.0 wt％がより好ましい。ケイ素化合物としては
メタ珪酸ソーダ、オルト珪酸ソーダ、水ガラスが使用出
来、その添加量はオキシ水酸化鉄中の鉄に対してケイ素
として 0.1〜５wt％が好ましく、さらに好ましくは 0.2
〜３wt％である。本発明で使用される形状保持剤として
は、Si，Al，B ，P のうち少なくとも１種類またはその
組合せが使用出来る。As the ferrous salt used in the present invention, ferrous chloride, ferrous sulfate and ferrous nitrate can be used. Examples of the alkali include alkali hydroxides such as sodium hydroxide and potassium hydroxide, alkali carbonates such as sodium carbonate and ammonium carbonate, and ammonia. Further, as the oxidizing gas, a known gas such as oxygen gas and air can be used. As the iron oxyhydroxide thus obtained, α-FeOOH, β-FeOOH, γ-FeOO
H and the like, and α-FeOOH and γ-FeOOH are particularly preferable. The shape of the iron oxyhydroxide has a major axis length of 0.05 to
Needles, columns, spindles, and rods having a diameter of 0.3 μm and an axial ratio of 3 to 15 are preferable, and Co, Ni, Cr, Mn, Mg, Ca,
It is also effective when metal compounds such as Ba, Sr, Zn, Ti, Mo, Ag, and Cu are included. The rare earth elements used in the present invention are
It is at least one of La, Ce, Pr, Nd, Sm, Gd, Dy, and Y, and a combination of these is also effective. The addition amount is preferably 0.3 to 10% by weight based on the iron in the iron oxyhydroxide,
0.5-5.0 wt% is more preferable. As the silicon compound, sodium metasilicate, sodium orthosilicate and water glass can be used, and the addition amount thereof is preferably 0.1 to 5% by weight as silicon with respect to iron in iron oxyhydroxide, and more preferably 0.2 to 0.2%.
~ 3 wt%. As the shape retaining agent used in the present invention, at least one of Si, Al, B, and P or a combination thereof can be used.

【０００７】本発明について、オキシ水酸化鉄を針状の
α−FeOOH とした場合を例として説明する。先ず、第一
鉄塩とアルカリを混合した水懸濁液に、酸化性ガスを吹
き込むことによって針状α−FeOOH を主体とする種結晶
を製造する。この時の酸化反応の温度は40〜70℃で、pH
は10.5以上が望ましい。またこの時、Co，Ni，Cr，Mn，
Mg，Ca，Ba，Sr，Zn，Ti，Mo，Ag，Cu等の金属化合物が
添加されていてもよい。次に種結晶の粒子表面に、酸化
反応終了後、または酸化反応途中において、該懸濁液に
非酸化性雰囲気下、酸化反応終了後の場合には懸濁液に
第一鉄塩水溶液および稀土類元素化合物および／または
ケイ素化合物の水溶液を加えた後、酸化反応途中の場合
には稀土類元素化合物および／またはケイ素化合物の水
溶液を加え、酸化反応温度以上の温度で熟成後、再び酸
化性ガスを吹き込んで針状α−FeOOHの結晶を成長させ
る。この反応で稀土類元素化合物および／またはケイ素
化合物の添加方法は種々あるが、酸化反応終了後の場合
には、添加する第一鉄水溶液と稀土類化合物水溶液を別
々に添加しても、予め混合した水溶液を添加してもよ
い。ケイ素化合物水溶液は酸化反応終了後、第一鉄塩水
溶液を添加する前のα−FeOOH の懸濁液中に添加しても
よいし、また第一鉄塩水溶液を添加した後、この水酸化
第一鉄とα−FeOOH の懸濁液中に添加してもよい。この
工程で添加される第一鉄塩の量は添加される鉄／α−Fe
OOH 中の鉄比で10〜50モル％が好ましい。これより少な
いと添加する稀土類元素化合物および／またはケイ素化
合物が完全に成長時に取り込まれない。これより多いと
成長がうまく行われず、新たにα−ＦｅＯＯＨ結晶の核
の生成が起こり、粒子の揃いが悪くなる。熟成及び成長
反応の温度は酸化反応の温度以上で行うことが望まし
い。成長反応が酸化反応温度以下で行われると成長がう
まく行われず、新たに核の生成が起こり、粒子の揃いが
悪くなる。また反応途中で稀土類元素化合物および／ま
たはケイ素化合物を添加する場合には稀土類化合物の水
溶液を水酸化第一鉄とα−FeOOH の懸濁液に添加しても
よいし、ケイ素化合物の水溶液を水酸化第一鉄とα−Fe
OOH 懸濁液に添加してもよい。また稀土類化合物とケイ
素化合物の両方を添加する場合には、反応途中の水酸化
第一鉄とα−FeOOH 懸濁液にそれぞれの化合物の水溶液
を添加してもよいし、予め両者をよく混合して添加して
もよい。この時の酸化反応率は50〜90％が適当である。
酸化反応率が50％より低いときに添加すると、新たに核
が生成し、粒子の揃いが悪くなり、また酸化反応率が90
％を越えたときに添加すると、添加する稀土類元素化合
物および／またはケイ素化合物が完全に成長時に取り込
まれない。またこの工程で添加される稀土類元素は添加
される鉄＋α−FeOOH 中の鉄に対し、 0.3〜10wt％が好
ましく、またケイ素量は 0.1〜5.0wt ％の範囲が好まし
い。これより量が少ないと期待される形状保持効果が得
られず、保磁力の向上が望めない。これより量が多いと
飽和磁束密度が低下したり、還元に長時間を要する等の
問題が出てくる。この工程で使用される第一鉄塩および
稀土類元素化合物としては、塩化物、硫酸塩、硝酸塩等
の水溶性塩が使用できる。次いで、粒子の表面近傍に稀
土類元素化合物および／またはケイ素化合物をドープし
たα−FeOOH 懸濁液を攪拌しながら、Al，Si，B ，Pの
化合物の単独もしくはこれら化合物の組合せを含む水溶
液を添加し、pHを酸、またはアルカリを添加して５〜10
に調整することで被着し、濾過、洗浄、乾燥する。次い
で、非還元性雰囲気中で 500〜800 ℃の温度で加熱処理
し、しかる後、還元性ガスで加熱還元することで金属磁
性粉末を得る。The present invention will be described by taking as an example the case where iron oxyhydroxide is formed into acicular α-FeOOH. First, an oxidizing gas is blown into an aqueous suspension in which a ferrous salt and an alkali are mixed to produce a seed crystal mainly composed of acicular α-FeOOH. The temperature of the oxidation reaction at this time is 40-70 ° C, and the pH is
Is preferably 10.5 or more. At this time, Co, Ni, Cr, Mn,
Metal compounds such as Mg, Ca, Ba, Sr, Zn, Ti, Mo, Ag, and Cu may be added. Next, after the oxidation reaction is completed or during the oxidation reaction, the suspension is placed under a non-oxidizing atmosphere on the surface of the seed crystal particles. After the aqueous solution of the elemental compound and / or the silicon compound is added, if the oxidation reaction is in progress, an aqueous solution of the rare earth element compound and / or the silicon compound is added, and after aging at a temperature higher than the oxidation reaction temperature, the oxidizing gas is again added. To grow acicular α-FeOOH crystals. There are various methods for adding a rare earth element compound and / or a silicon compound in this reaction. In the case of completion of the oxidation reaction, a ferrous aqueous solution and a rare earth compound aqueous solution to be added may be added separately or mixed. The added aqueous solution may be added. After the oxidation reaction, the silicon compound aqueous solution may be added to the α-FeOOH suspension before the addition of the ferrous salt aqueous solution, or after the addition of the ferrous salt aqueous solution, It may be added to a suspension of ferrous iron and α-FeOOH. The amount of ferrous salt added in this step depends on the iron / α-Fe added.
The iron ratio in OOH is preferably 10 to 50 mol%. If the amount is less than this, the added rare earth element compound and / or silicon compound will not be completely taken in during growth. If it is more than this, the growth is not performed well, nuclei of α-FeOOH crystals are newly generated, and the uniformity of the particles is deteriorated. It is desirable that the temperature of the ripening and growth reactions be higher than the temperature of the oxidation reaction. If the growth reaction is performed at a temperature lower than the oxidation reaction temperature, the growth is not performed well, nuclei are newly generated, and the uniformity of the particles is deteriorated. When a rare earth element compound and / or silicon compound is added during the reaction, an aqueous solution of the rare earth compound may be added to a suspension of ferrous hydroxide and α-FeOOH, or an aqueous solution of the silicon compound may be added. With ferrous hydroxide and α-Fe
It may be added to the OOH suspension. When both the rare earth compound and the silicon compound are added, an aqueous solution of each compound may be added to the suspension of ferrous hydroxide and α-FeOOH during the reaction, or both may be mixed well in advance. May be added. The oxidation reaction rate at this time is suitably from 50 to 90%.
If the addition is performed when the oxidation reaction rate is lower than 50%, nuclei are newly formed, the particles become less uniform, and the oxidation reaction rate is reduced to 90%.
%, The added rare earth element compound and / or silicon compound will not be completely incorporated during growth. The rare earth element added in this step is preferably 0.3 to 10% by weight, and the silicon content is preferably in the range of 0.1 to 5.0% by weight based on the iron in the added iron + α-FeOOH. If the amount is less than this, the expected shape retention effect cannot be obtained, and an improvement in coercive force cannot be expected. If the amount is larger than this, there arise problems such as a decrease in the saturation magnetic flux density and a long time for reduction. As the ferrous salt and the rare earth element compound used in this step, water-soluble salts such as chlorides, sulfates and nitrates can be used. Then, while stirring the α-FeOOH suspension doped with a rare earth element compound and / or a silicon compound in the vicinity of the surface of the particles, an aqueous solution containing a compound of Al, Si, B, or P alone or a combination of these compounds is added. PH is adjusted to 5-10 by adding acid or alkali.
And then filtered, washed and dried. Next, a heat treatment is carried out at a temperature of 500 to 800 ° C. in a non-reducing atmosphere, and thereafter, a metal magnetic powder is obtained by heating and reducing with a reducing gas.

【０００８】[0008]

【作用】本発明の第一の効果は加熱還元時の粒子の形状
保持効果にある。従来の技術においても粒子表面にAl，
Si，B , P 等の化合物の一種、またはこれらの組合せを
存在させ、形状保持効果を得ているが、本発明では、形
状保持剤の下層に稀土類元素化合物および／またはケイ
素化合物をドープさせておくことにより、形状保持効果
がさらに優れたものになり、その結果として、ほぼ同じ
サイズの粒子で従来技術で製造したものと、粉体磁気特
性を比較すると、保磁力が顕著に高くなり、角型比も向
上する。また、温度＝60℃、相対湿度＝90％雰囲気中で
１週間放置した後の飽和磁束密度（σs ）の保持率も高
く、酸化安定性にも優れている。さらに、この金属磁性
粉末をテープ化して磁気特性を測定すると、Br，角型
比、Ｓ．Ｆ．Ｄ（突発性周波数変動）が従来技術で製造
したものに比較して優れている。このことは、本発明で
製造した金属磁性粉が塗料中での分散性、パッキング性
に優れることを示している。また、テープでのＳ．Ｆ．
Ｄ．が小さいことは、粉体の保磁力分布がシャープであ
ることを示している。本発明で得られた金属磁性粉末の
この優れた特性の発現理由については明らかではない
が、形状保持剤の下層に難還元性で、酸素との親和力の
強い稀土類元素化合物および／またはケイ素化合物が存
在することにより、熱処理時の熱による歪みで粒子表面
の形状保持剤と内部の鉄を主体とする酸化物が遊離した
り、加熱還元時に、内部の酸化物が還元され収縮して粒
子内に空孔を生じたり、粒子がちぎれたり、粒子の一部
分だけが還元が進行してコブのついた粒子になったり、
あるいは粒子同士が焼結すること等を防止する効果が顕
著に現れるためと考えられる。The first effect of the present invention resides in the effect of maintaining the shape of particles during heat reduction. In the conventional technology, Al,
One of compounds such as Si, B, and P or a combination thereof is present to obtain a shape-retaining effect. In the present invention, however, a rare earth element compound and / or a silicon compound is doped in a lower layer of the shape-retaining agent. By doing so, the shape retention effect becomes even better, as a result, when compared with those manufactured by conventional technology with particles of almost the same size, the coercive force is significantly higher, The squareness ratio is also improved. Further, it has a high retention rate of the saturation magnetic flux density (σs) after being left for one week in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90%, and has excellent oxidation stability. Further, when the magnetic properties of the metal magnetic powder were taped and measured, the Br, squareness ratio, S.P. F. D (sudden frequency fluctuation) is superior to that manufactured by the prior art. This indicates that the metal magnetic powder produced in the present invention is excellent in dispersibility and packing property in paint. In addition, S.P. F.
D. Is small indicates that the coercive force distribution of the powder is sharp. It is not clear why the metal magnetic powder obtained in the present invention exhibits such excellent properties, but a rare-earth element compound and / or a silicon compound which are hardly reducible and have a strong affinity for oxygen are formed in the lower layer of the shape-retaining agent. Is present, the shape-maintaining agent on the particle surface and the oxide mainly composed of iron are released by heat distortion during heat treatment, or the internal oxide is reduced and shrunk during heat reduction to reduce the particle size. Vacancies occur, particles are torn off, only a part of the particles undergoes reduction to become bumpy particles,
Alternatively, it is considered that the effect of preventing sintering of the particles is remarkably exhibited.

【０００９】[0009]

【実施例】以下に実施例を挙げて本発明を更に詳しく説
明するが、本発明はこれらに限定されるものではない。EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

【００１０】実施例１ 窒素ガスを流して酸化性ガスを追い出した容器に、2.0m
ol/lの塩化第一鉄水溶液４リットルと1.5mol/lの水酸化
ナトリウム水溶液20リットルを混合した懸濁液に、空気
を１時間吹き込むことによって、完全に酸化し、針状の
α−FeOOH を得た。この時の反応は40℃の温度で行っ
た。この懸濁液に非酸化性雰囲気下で、0.5mol/lの塩化
第一鉄水溶液２リットルおよび0.1mol/lの塩化ランタン
水溶液１リットルを加え、１時間攪拌した。この時の熟
成は45℃の温度で行った。この後再び空気を吹き込み、
ランタンを表面にドープした針状のα−FeOOH を得た。
このα−FeOOH を濾過、水洗後、再び40リットルの蒸留
水に分散させ、この懸濁液に0.5mol/lの塩化アルミニュ
ーム水溶液２リットルを添加して30分間攪拌した。水酸
化ナトリウム水溶液を徐々に添加して懸濁液のpHを８に
調整して、水酸化アルミニュームを針状のα−FeOOH 粒
子の表面に被覆した。この懸濁液を濾過、水洗後、120
℃の乾燥器中で乾燥した。この乾燥ケーキを窒素雰囲気
中 700℃で３時間熱処理し、次いで、水素ガス流下 470
℃の温度で６時間還元した。還元後、ガスを窒素ガスに
変え、温度を室温まで下げた後、窒素ガス流中に空気を
徐々に流して、常法により安定化処理を行って長軸長
0.2μm、軸比10の金属磁性粉末を得た。透過電子顕微鏡
で粒子を観察したところ、形崩れや焼結のない、また粒
子中に空孔の少ない粒子であった粉末の磁気特性及び温
度＝60℃、相対湿度＝90％中での１週間後の飽和磁束密
度（σs ）の数値を表１に示した。また、得られた金属
磁性粉末をテープ化して測定した磁気特性を表２に示し
た。テープ化は以下の方法で行った。又、以下の実施
例、比較例についても同様に、金属磁性粉末の磁気特性
を表１に、テープにした場合の磁気特性を表２に示し
た。Example 1 A container having a flow of nitrogen gas to expel an oxidizing gas was placed in a container of 2.0 m.
ol / l ferrous chloride aqueous solution (4 liters) and 1.5 mol / l sodium hydroxide aqueous solution (20 liters) were mixed and completely oxidized by blowing air into the suspension for 1 hour to obtain acicular α-FeOOH. I got The reaction at this time was performed at a temperature of 40 ° C. Under a non-oxidizing atmosphere, 2 liters of a 0.5 mol / l ferrous chloride aqueous solution and 1 liter of a 0.1 mol / l lanthanum chloride aqueous solution were added to the suspension and stirred for 1 hour. The aging at this time was performed at a temperature of 45 ° C. After this, air is blown again,
Acicular α-FeOOH doped with lanthanum on the surface was obtained.
The α-FeOOH was filtered, washed with water, dispersed again in 40 l of distilled water, and 2 l of a 0.5 mol / l aluminum chloride aqueous solution was added to the suspension and stirred for 30 minutes. An aqueous sodium hydroxide solution was gradually added to adjust the pH of the suspension to 8, and aluminum hydroxide was coated on the surfaces of the acicular α-FeOOH particles. The suspension is filtered, washed with water,
Dried in a desiccator at ℃. The dried cake is heat-treated at 700 ° C. for 3 hours in a nitrogen atmosphere, and then dried under a hydrogen gas flow.
Reduction at a temperature of 6 ° C. for 6 hours. After the reduction, the gas was changed to nitrogen gas, the temperature was lowered to room temperature, air was gradually flowed into the nitrogen gas flow, and stabilization was performed by a conventional method to obtain a long axis.
A metal magnetic powder having 0.2 μm and an axial ratio of 10 was obtained. Observation of the particles with a transmission electron microscope revealed that the particles had no deformation or sintering, and had few pores in the particles. The magnetic properties of the powder and one week at a temperature of 60 ° C and a relative humidity of 90% Table 1 shows the values of the subsequent saturation magnetic flux density (σs). In addition, Table 2 shows the magnetic properties measured by tape-forming the obtained metal magnetic powder. The tape was formed by the following method. Similarly, Table 1 shows the magnetic properties of the metal magnetic powder and Table 2 shows the magnetic properties when the tape was used for the following Examples and Comparative Examples.

【００１１】テープ化の方法及び評価 金属粉末100gとポリウレタン樹脂11g 、塩化ビニル−酢
酸ビニル共重合体7.75g 、トルエン／メチルエチルケト
ン／シクロヘキサノン＝１／１／１の混合溶液345gとを
混合し、サンドグラインダーで５時間分散を行って磁性
塗料を作成した。この塗料に架橋剤としてコロネートＬ
を2.5g添加したのち、ポリエステルフィルムに塗布し、
3000ガウスの磁界を印加して、50℃の温度で乾燥した。
次いで80℃、線圧200Kg/cmでカレンダー処理を行い、60
℃で24時間熟成を行った後、カットしてＶＳＭ磁力計を
用いて最大印加磁場５kOe で磁気特性を測定した。 Method and evaluation of tape formation 100 g of metal powder, 11 g of polyurethane resin, 7.75 g of vinyl chloride-vinyl acetate copolymer, and 345 g of a mixed solution of toluene / methyl ethyl ketone / cyclohexanone = 1/1/1 were mixed, and the mixture was sand-sanded. For 5 hours to produce a magnetic paint. Coronate L is used as a crosslinking agent in this paint.
After adding 2.5 g, apply to polyester film,
Drying was performed at a temperature of 50 ° C. by applying a magnetic field of 3000 gauss.
Next, calendering was performed at 80 ° C and a linear pressure of 200 kg / cm,
After aging at 24 ° C. for 24 hours, it was cut, and the magnetic properties were measured using a VSM magnetometer at a maximum applied magnetic field of 5 kOe.

【００１２】実施例２〜４ 稀土類金属元素の種類および添加量を変えた以外は実施
例１と同様にして金属磁性粉末を得た。Examples 2 to 4 Metal magnetic powders were obtained in the same manner as in Example 1 except that the kind and amount of the rare earth metal element were changed.

【００１３】実施例５ 窒素ガスを流して酸化性ガスを追い出した容器に、8.0m
olの塩化第一鉄と0.3molの塩化ニッケルを４リットルの
蒸留水に溶解した混合溶液と1.5mol/lの水酸化ナトリウ
ム水溶液20リットルを混合した懸濁液に、空気を１時間
吹き込むことによって完全に酸化し、針状のα−FeOOH
を得た。この時の反応は40℃の温度で行った。この懸濁
液に非酸化性雰囲気下0.5mol/lの塩化第一鉄水溶液２リ
ットルおよびSiO₂換算で100g/lの濃度の水ガラスを75ml
加え、１時間攪拌した。この時の熟成は45℃の温度で行
った。この後再び空気を吹き込みケイ素化合物を表面に
ドープした針状のα−FeOOH を得た。この針状のα−Fe
OOH を濾過、水洗後、再び40リットルの蒸留水に分散さ
せ、この懸濁液に0.5mol/lの塩化アルミニューム水溶液
２リットルを添加し、30分攪拌した。水酸化ナトリウム
水溶液を徐々に添加してpHを８に調整して水酸化アルミ
ニュームを針状のα−FeOOH の表面に被覆した。この懸
濁液を濾過、水洗後 120℃の乾燥機中で乾燥した。この
乾燥ケーキを窒素雰囲気下、 700℃で３時間熱処理し、
次いで水素ガス流下、 470℃の温度で６時間還元を行っ
た。還元後、ガスを窒素ガスに変え、温度を室温まで下
げた後、窒素ガス流中に空気を徐々に流して常法により
安定化処理を行って金属磁性粉末を得た。Example 5 In a container in which nitrogen gas was flowed to expel oxidizing gas, 8.0 m
ol ferrous chloride and 0.3 mol of nickel chloride dissolved in 4 liters of distilled water and 20 liters of a 1.5 mol / l aqueous sodium hydroxide solution were mixed with a suspension of air for 1 hour. Completely oxidized, acicular α-FeOOH
I got The reaction at this time was performed at a temperature of 40 ° C. 75 ml of a water glass having a concentration of 100 g / l in terms of SiO ₂ and 2 liters of a 0.5 mol / l ferrous chloride aqueous solution in a non-oxidizing atmosphere
The mixture was stirred for 1 hour. The aging at this time was performed at a temperature of 45 ° C. Thereafter, air was blown again to obtain needle-like α-FeOOH doped with a silicon compound on the surface. This acicular α-Fe
After OOH was filtered and washed with water, it was dispersed again in 40 liters of distilled water, and 2 liters of a 0.5 mol / l aluminum chloride aqueous solution was added to the suspension, followed by stirring for 30 minutes. Aqueous sodium hydroxide was gradually added to adjust the pH to 8, and aluminum hydroxide was coated on the surface of the needle-like α-FeOOH. The suspension was filtered, washed with water and dried in a dryer at 120 ° C. This dried cake is heat-treated under nitrogen atmosphere at 700 ° C for 3 hours,
Next, reduction was carried out at a temperature of 470 ° C. for 6 hours under a flow of hydrogen gas. After the reduction, the gas was changed to nitrogen gas, and the temperature was lowered to room temperature. Then, air was gradually flowed into the nitrogen gas flow to perform a stabilization treatment by a conventional method to obtain a metal magnetic powder.

【００１４】実施例６ 窒素ガスを流して、酸化性ガスを追い出した容器に、8.
0molの塩化第一鉄と0.25mol の塩化ニッケルを４リット
ルの蒸留水に溶解した混合溶液と1.5mol/lの水酸化ナト
リウム水溶液20リットルを混合した懸濁液に、空気を40
分間吹き込むことによって、第一鉄の70％を酸化した。
この時の反応は40℃の温度で行った。この懸濁液に非酸
化性雰囲気下、0.1mol/lの塩化ネオジム１リットルおよ
びSiO₂換算で、100g/lの濃度の水ガラスを70ml加え、１
時間攪拌した。この時の熟成は45℃の温度で行った。こ
の後再び空気を吹き込み、ネオジム化合物及びケイ素化
合物をドープした針状のα−FeOOH を得た。この針状の
α−FeOOH を濾過、水洗後、再び40リットルの蒸留水に
分散させ、この懸濁液に0.5mol/lの塩化アルミニューム
水溶液２リットルを添加し、30分攪拌した。水酸化ナト
リウム水溶液を徐々に添加してpHを８に調整し、水酸化
アルミニュームを針状のα−FeOOH の表面に被覆した。
この懸濁液を濾過、水洗後 120℃の乾燥器中で10時間乾
燥した。この乾燥ケーキを窒素雰囲気中 700℃の温度で
３時間熱処理し、次いで水素ガス流下、500 ℃の温度で
６時間還元を行った。還元後、ガスを窒素ガスに変え、
温度を室温まで下げた後、窒素ガス流中に空気を徐々に
流して常法により安定化処理を行って金属磁性粉末を得
た。Example 6 A container in which nitrogen gas was flown to remove oxidizing gas was placed in a container.
40 ml of air was added to a suspension obtained by mixing 0 mol of ferrous chloride and 0.25 mol of nickel chloride in 4 liters of distilled water and 20 liters of a 1.5 mol / l sodium hydroxide aqueous solution.
By blowing for a minute, 70% of the ferrous iron was oxidized.
The reaction at this time was performed at a temperature of 40 ° C. To this suspension was added 1 ml of 0.1 mol / l neodymium chloride and 70 ml of water glass having a concentration of 100 g / l in terms of SiO ₂ under a non-oxidizing atmosphere, and
Stirred for hours. The aging at this time was performed at a temperature of 45 ° C. Thereafter, air was blown again to obtain acicular α-FeOOH doped with a neodymium compound and a silicon compound. The needle-like α-FeOOH was filtered, washed with water, dispersed again in 40 l of distilled water, and 2 l of a 0.5 mol / l aluminum chloride aqueous solution was added to the suspension and stirred for 30 minutes. An aqueous solution of sodium hydroxide was gradually added to adjust the pH to 8, and aluminum hydroxide was coated on the surface of the needle-like α-FeOOH.
The suspension was filtered, washed with water and dried in a dryer at 120 ° C. for 10 hours. The dried cake was heat-treated in a nitrogen atmosphere at a temperature of 700 ° C. for 3 hours, and then reduced under a flow of hydrogen gas at a temperature of 500 ° C. for 6 hours. After reduction, change the gas to nitrogen gas,
After the temperature was lowered to room temperature, air was gradually flown in a nitrogen gas flow to perform a stabilization treatment by an ordinary method, to obtain a metal magnetic powder.

【００１５】実施例７ 窒素ガスを流して酸化性ガスを追い出した容器に、8.0m
olの塩化第一鉄と0.25mol の塩化ニッケルを４リットル
の蒸留水に溶解した混合溶液と1.5mol/lの水酸化ナトリ
ウム水溶液20リットルを混合した懸濁液に、空気を40分
間吹き込むことによって、第一鉄の70％を酸化した。こ
の時の反応は40℃の温度で行った。この懸濁液に非酸化
性雰囲気下、0.1mol/lの塩化ネオジム１リットルおよび
SiO₂換算で100g/l濃度の水ガラスを70ml加え、１時間攪
拌した。この時の熟成は45℃の温度で行った。この後再
び空気を吹き込み、ネオジム化合物およびケイ素化合物
をドープした針状のα−FeOOH を得た。この針状のα−
FeOOH を濾過、水洗後、再び40リットルの蒸留水に分散
させ、この懸濁液に成長反応に使用したものと同じ濃度
の水ガラス900ml を添加し、30分攪拌した。塩酸水溶液
を徐々に添加してpHを８に調整してケイ素化合物を針状
のα−FeOOH の表面に被覆した。この懸濁液を濾過、水
洗して 120℃の乾燥器中で10時間乾燥した。この乾燥ケ
ーキを窒素雰囲気中 600℃の温度で３時間熱処理し、次
いで、水素ガス流下 520℃で６時間還元した。安定化は
実施例１と同じように行い金属磁性粉末を得た。Example 7 A container which was purged with an oxidizing gas by flowing nitrogen gas was charged with 8.0 m.
ol ferrous chloride and 0.25 mol of nickel chloride dissolved in 4 liters of distilled water and 20 liters of a 1.5 mol / l aqueous sodium hydroxide solution were mixed with a suspension of air for 40 minutes. Oxidized 70% of ferrous iron. The reaction at this time was performed at a temperature of 40 ° C. One liter of 0.1 mol / l neodymium chloride was added to this suspension in a non-oxidizing atmosphere.
70 ml of water glass having a concentration of 100 g / l in terms of SiO ₂ was added and stirred for 1 hour. The aging at this time was performed at a temperature of 45 ° C. Thereafter, air was blown again to obtain acicular α-FeOOH doped with a neodymium compound and a silicon compound. This needle-shaped α-
After FeOOH was filtered and washed with water, it was dispersed again in 40 liters of distilled water, and 900 ml of water glass having the same concentration as that used in the growth reaction was added to the suspension, followed by stirring for 30 minutes. Hydrochloric acid aqueous solution was gradually added to adjust the pH to 8, and the silicon compound was coated on the surface of the needle-like α-FeOOH. This suspension was filtered, washed with water and dried in a dryer at 120 ° C. for 10 hours. The dried cake was heat-treated in a nitrogen atmosphere at a temperature of 600 ° C. for 3 hours, and then reduced at 520 ° C. for 6 hours under a flow of hydrogen gas. Stabilization was performed in the same manner as in Example 1 to obtain a metal magnetic powder.

【００１６】実施例８ 窒素ガスを流して、酸化性ガスを追い出した容器に、2.
0mol/lの塩化第一鉄水溶液４リットルと２mol/l の塩化
コバルト水溶液 200mlおよび1.5mol/lの水酸化ナトリウ
ム水溶液20リットルを混合した懸濁液に、空気を40分間
吹き込むことによって、第一鉄の70％を酸化した。この
時の反応は40℃の温度で行った。この懸濁液に非酸化性
雰囲気下、0.1mol/lの塩化ネオジム水溶液を１リットル
およびSiO₂換算で100g/lの濃度の水ガラスを70ml加え、
１時間攪拌した。この時の熟成は45℃の温度で行った。
この後再び空気を吹き込みネオジム化合物およびケイ素
化合物をドープした針状のα−FeOOH を得た。この針状
のα−FeOOH を濾過、水洗後、再び40リットルの蒸留水
に分散させ、この懸濁液に0.5mol/lの塩化アルミニュー
ム水溶液１リットルを添加し、30分攪拌した。水酸化ナ
トリウム水溶液を徐々に添加してpHを８に調整して、水
酸化アルミニュームを針状のα−FeOOH に被覆した。こ
の懸濁液を濾過、水洗後、圧搾して水分を良く絞った湿
ケーキを得た。この湿ケーキに0.25mol の硼酸をできる
だけ少量の蒸留水に溶解した水溶液を加え、十分に混合
し、 120℃の乾燥器中で10時間乾燥した。この乾燥ケー
キを窒素雰囲気下 550℃の温度で熱処理し、次いで、水
素ガス流下、 480℃の温度で６時間還元した。安定化は
実施例１と同様に行い金属磁性粉末を得た。Example 8 In a container in which nitrogen gas was flown to expel oxidizing gas, 2.
By blowing air for 40 minutes into a suspension obtained by mixing 4 liters of a 0 mol / l ferrous chloride aqueous solution, 200 ml of a 2 mol / l aqueous cobalt chloride solution and 20 liters of a 1.5 mol / l aqueous sodium hydroxide solution for 40 minutes, 70% of the iron was oxidized. The reaction at this time was performed at a temperature of 40 ° C. Under a non-oxidizing atmosphere, 1 liter of a 0.1 mol / l neodymium chloride aqueous solution and 70 ml of water glass having a concentration of 100 g / l in terms of SiO ₂ were added to the suspension.
Stir for 1 hour. The aging at this time was performed at a temperature of 45 ° C.
Thereafter, air was blown again to obtain acicular α-FeOOH doped with a neodymium compound and a silicon compound. The needle-like α-FeOOH was filtered, washed with water, dispersed again in 40 liters of distilled water, and 1 liter of a 0.5 mol / l aqueous solution of aluminum chloride was added to the suspension, followed by stirring for 30 minutes. An aqueous sodium hydroxide solution was gradually added to adjust the pH to 8, and aluminum hydroxide was coated on α-FeOOH in the form of needles. The suspension was filtered, washed with water, and squeezed to obtain a wet cake whose moisture was well squeezed. An aqueous solution in which 0.25 mol of boric acid was dissolved in as little distilled water as possible was added to the wet cake, mixed well, and dried in a dryer at 120 ° C. for 10 hours. This dried cake was heat-treated at a temperature of 550 ° C. under a nitrogen atmosphere and then reduced at a temperature of 480 ° C. for 6 hours under a flow of hydrogen gas. Stabilization was performed in the same manner as in Example 1 to obtain a metal magnetic powder.

【００１７】実施例９ 窒素ガスを流して酸化性ガスを追い出した容器に、2.0m
ol/lの塩化第一鉄水溶液４リットルと2.0mol/lの塩化コ
バルト水溶液200ml 、および0.5mol/lの炭酸ナトリウム
水溶液20リットルを混合した懸濁液に、空気を１時間吹
き込むことによって、完全に酸化し紡錘状のα−FeOOH
を得た。この時の反応は40℃の温度で行った。この懸濁
液に非酸化性雰囲気下、0.5mol/lの塩化第一鉄水溶液２
リットルおよび0.1mol/lの塩化ネオジム水溶液１リット
ルとSiO₂換算で100g/lの濃度の水ガラスを36ml加え、１
時間攪拌した。この時の熟成は45℃の温度で行った。こ
の後再び空気を吹き込みネオジム化合物およびケイ素化
合物をドープした紡錘状のα−FeOOH を得た。この紡錘
状のα−FeOOH を濾過、水洗後、再び40リットルの蒸留
水に分散させ、この懸濁液に成長反応で使用したのと同
じ濃度の水ガラス400ml を添加し、30分間攪拌した。塩
酸水溶液を徐々に添加しpHを８に調整し、ついで0.5mol
/lの塩化アルミニューム水溶液１リットルを添加し、30
分間攪拌した。水酸化ナトリウム水溶液を徐々に添加し
pHを８に調整し、紡錘状のα−FeOOHの表面にケイ素化
合物および水酸化アルミニュームを被覆した。この懸濁
液を濾過、水洗後 120℃の乾燥器中で10時間乾燥した。
この乾燥ケーキを窒素雰囲気中 500℃で３時間熱処理
し、次いで、水素ガス流下 480℃で６時間還元した。安
定化処理は実施例１と同様に行い金属磁性粉末を得た。Example 9 A container, into which a nitrogen gas was flowed to expel an oxidizing gas, was charged with a 2.0 m
air was blown for 1 hour into a suspension prepared by mixing 4 liters of an aqueous solution of 1 mol / l ferrous chloride, 200 ml of a 2.0 mol / l aqueous solution of cobalt chloride, and 20 liters of a 0.5 mol / l aqueous solution of sodium carbonate. Spindle-shaped α-FeOOH
I got The reaction at this time was performed at a temperature of 40 ° C. A 0.5 mol / l ferrous chloride aqueous solution 2 was added to this suspension under a non-oxidizing atmosphere.
1 liter and 1 liter of an aqueous 0.1 mol / l neodymium chloride solution and 36 ml of water glass having a concentration of 100 g / l in terms of SiO ₂ were added.
Stirred for hours. The aging at this time was performed at a temperature of 45 ° C. Thereafter, air was blown again to obtain a spindle-shaped α-FeOOH doped with a neodymium compound and a silicon compound. The spindle-shaped α-FeOOH was filtered, washed with water, dispersed again in 40 liters of distilled water, and 400 ml of water glass having the same concentration as that used in the growth reaction was added to the suspension, followed by stirring for 30 minutes. Aqueous hydrochloric acid is gradually added to adjust the pH to 8, then 0.5 mol
1 liter of an aluminum chloride aqueous solution
Stirred for minutes. Slowly add aqueous sodium hydroxide
The pH was adjusted to 8, and the surface of the spindle-shaped α-FeOOH was coated with a silicon compound and aluminum hydroxide. The suspension was filtered, washed with water and dried in a dryer at 120 ° C. for 10 hours.
This dried cake was heat-treated at 500 ° C. for 3 hours in a nitrogen atmosphere, and then reduced at 480 ° C. for 6 hours under a flow of hydrogen gas. The stabilization treatment was performed in the same manner as in Example 1 to obtain a metal magnetic powder.

【００１８】比較例１ ランタン化合物をドープしなかった以外は実施例１と同
様な操作で金属磁性粉末を得た。Comparative Example 1 A metal magnetic powder was obtained in the same manner as in Example 1 except that the lanthanum compound was not doped.

【００１９】金属磁性粉末を透過型電子顕微鏡で観察し
たところ、粒子の形崩れや粒子中に空孔のあるものが目
立った。When the metal magnetic powder was observed with a transmission electron microscope, it was found that the particles had collapsed shape or had voids in the particles.

【００２０】比較例２ ケイ素化合物をドープしなかった以外は実施例５と同様
な操作で金属磁性粉末を得た。Comparative Example 2 A metal magnetic powder was obtained in the same manner as in Example 5 except that the silicon compound was not doped.

【００２１】比較例３ ネオジム化合物、ケイ素化合物をドープしなかった以外
は実施例７と同様な操作で金属磁性粉末を得た。Comparative Example 3 A metal magnetic powder was obtained in the same manner as in Example 7, except that the neodymium compound and the silicon compound were not doped.

【００２２】比較例４ ネオジム化合物、ケイ素化合物をドープしなかった以外
は実施例９と同様な操作で金属磁性粉末を得た。Comparative Example 4 A metal magnetic powder was obtained in the same manner as in Example 9 except that the neodymium compound and the silicon compound were not doped.

【００２３】[0023]

【表１】 [Table 1]

【００２４】（表１の注） *1 ：（ ）内は種結晶のオキシ水酸化鉄中にドープさ
れている金属。 *2 ：窒素吸着法で測定した比表面積値。 *3 ：温度＝60℃、相対湿度＝90％中に１週間放置した
後のσs 値。(Notes in Table 1) * 1: (): Metal doped in seed crystal iron oxyhydroxide. * 2: Specific surface area value measured by nitrogen adsorption method. * 3: σs value after standing for one week in temperature = 60 ° C and relative humidity = 90%.

【００２５】[0025]

【表２】 [Table 2]

【００２６】[0026]

【発明の効果】表１，２で明らかなように、本発明で得
られた金属磁性粉末は従来の方法で得られたものに比較
して保磁力が高く、分散性も良好であり、且つ酸化安定
性も優れているものである。テープにした時のＳ．Ｆ．
Ｄ値も小さく、保磁力分布もシャープであることを示し
ている。従って、高密度磁気記録媒体用の磁性粉として
好適のものである。特に、金属磁性粉末の軸比が小さく
ても十分な保磁力が得られるので、短波長記録再生用の
媒体の磁性粉として最適のものである。As is clear from Tables 1 and 2, the metal magnetic powder obtained according to the present invention has a higher coercive force and better dispersibility than those obtained by the conventional method, and It also has excellent oxidation stability. S. when taped F.
The D value is also small, indicating that the coercive force distribution is sharp. Therefore, it is suitable as a magnetic powder for a high-density magnetic recording medium. In particular, since a sufficient coercive force can be obtained even when the axial ratio of the metal magnetic powder is small, it is optimal as a magnetic powder for a medium for short-wavelength recording and reproduction.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉田 功 群馬県渋川市金井425番地 関東電化工 業株式会社研究開発センター内 (56)参考文献 特開 平３−162508（ＪＰ，Ａ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) B22F 9/22 ────────────────────────────────────────────────── ─── Continued on the front page (72) Isao Yoshida, Inventor 425 Kanai, Shibukawa-shi, Gunma Kanto Denka Kogyo Co., Ltd. Research and Development Center (56) References JP-A-3-162508 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22F 9/22

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 第一鉄塩とアルカリを混合した水懸濁液
に、酸化性ガスを吹き込むことによって得られたオキシ
水酸化鉄を主体とする種結晶の粒子表面に、酸化反応途
中において、該懸濁液に非酸化性雰囲気下、稀土類元素
化合物および／またはケイ素化合物の水溶液を加え、酸
化反応温度以上の温度で熟成後、再び酸化性ガスを吹き
込んでオキシ水酸化鉄結晶を成長させた後、該オキシ水
酸化鉄の表面に形状保持剤を被覆し、次いで、非還元性
雰囲気下、 500〜800℃の温度で加熱処理し、しかる
後、還元性ガスで加熱還元することを特徴とする金属磁
性粉末の製造法。1. An oxidation reaction is performed on the particle surface of a seed crystal mainly composed of iron oxyhydroxide obtained by blowing an oxidizing gas into an aqueous suspension in which a ferrous salt and an alkali are mixed. An aqueous solution of a rare earth element compound and / or a silicon compound is added to the suspension under a non-oxidizing atmosphere, the mixture is aged at a temperature higher than the oxidation reaction temperature, and an oxidizing gas is blown again to grow iron oxyhydroxide crystals. After that, the surface of the iron oxyhydroxide is coated with a shape-retaining agent, and then heat-treated at a temperature of 500 to 800 ° C. in a non-reducing atmosphere, and then heat-reduced with a reducing gas. Method for producing metal magnetic powder. 【請求項２】 第一鉄塩とアルカリを混合した水懸濁液
に、酸化性ガスを吹き込むことによって得られたオキシ
水酸化鉄を主体とする種結晶の粒子表面に、酸化反応終
了後、該懸濁液に非酸化性雰囲気下、懸濁液に第一鉄塩
水溶液と稀土類元素化合物および／またはケイ素化合物
の水溶液を加えた後、酸化反応温度以上の温度で熟成
後、再び酸化性ガスを吹き込んでオキシ水酸化鉄結晶を
成長させた後、該オキシ水酸化鉄の表面に形状保持剤を
被覆し、次いで、非還元性雰囲気下、 500〜800 ℃の温
度で加熱処理し、しかる後、還元性ガスで加熱還元する
ことを特徴とする金属磁性粉末の製造法。2. After the oxidation reaction is completed, the surface of the seed crystal mainly composed of iron oxyhydroxide obtained by blowing an oxidizing gas into an aqueous suspension in which a ferrous salt and an alkali are mixed is mixed. Under a non-oxidizing atmosphere, an aqueous solution of a ferrous salt and an aqueous solution of a rare earth element compound and / or a silicon compound are added to the suspension, and the suspension is aged at a temperature higher than the oxidation reaction temperature. After blowing the gas to grow the iron oxyhydroxide crystals, the surface of the iron oxyhydroxide is coated with a shape-retaining agent, and then heat-treated at 500 to 800 ° C. in a non-reducing atmosphere. A method for producing a metallic magnetic powder, comprising reducing the composition by heating with a reducing gas.