JPH04299505A - Manufacture of needlelike magnetic ion oxide particle and powder for magnetic recording - Google Patents

Manufacture of needlelike magnetic ion oxide particle and powder for magnetic recording

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Publication number
JPH04299505A
JPH04299505A JP3089500A JP8950091A JPH04299505A JP H04299505 A JPH04299505 A JP H04299505A JP 3089500 A JP3089500 A JP 3089500A JP 8950091 A JP8950091 A JP 8950091A JP H04299505 A JPH04299505 A JP H04299505A
Authority
JP
Japan
Prior art keywords
compound
iron oxide
aqueous solution
magnetic iron
oxide particles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP3089500A
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Japanese (ja)
Other versions
JP2885252B2 (en
Inventor
Tomohisa Moriya
守谷 知久
Katsumi Yamashita
勝巳 山下
Hiroshi Oka
岡   宏
Kazuaki Kamishiro
和明 神代
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toda Kogyo Corp
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Toda Kogyo Corp
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Priority to JP3089500A priority Critical patent/JP2885252B2/en
Publication of JPH04299505A publication Critical patent/JPH04299505A/en
Application granted granted Critical
Publication of JP2885252B2 publication Critical patent/JP2885252B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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  • Compounds Of Iron (AREA)
  • Hard Magnetic Materials (AREA)

Abstract

PURPOSE:To provide the title magnetic ion oxide particles and powder with high coersive force and the magnetic with-time stability by containing a moderate and specific compound in a suspension. CONSTITUTION:When a Si compound is contained in the suspension, Co (OH)2 or Fe(OH)2 reacts to Si ions to produce a complex compound. Later, the reaction can be restrained by the resultant adherent reaction. Even if a needlelike magnetic particles powder are used as a precursor or a lot of Fe<+2> salt is added to enhance high coersive force and black color reaction, the adherent layer shall be composed of a Co compound containing Si produced by denaturizing a Si compound or an Fe compound containing Si. Through these procedures, the magnetic with-time stability can be enhanced while when the uppermost adherent layer is composed of the Co compound containing Si, the oxygen in the air does not come into contact with Fe<+2> so as to further enhance the effect.

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、高い保磁力を有し、且
つ、消去特性と保磁力分布に優れており、しかも、磁気
的な経時安定性の良い針状磁性酸化鉄粒子粉末の製造法
に関するものである。
[Industrial Application Field] The present invention is directed to the production of acicular magnetic iron oxide particles having high coercive force, excellent erasing properties and coercive force distribution, and good magnetic stability over time. It is about law.

【0002】0002

【従来の技術】近年、磁気記録再生用機器の小型軽量化
が進むにつれて磁気テープ、磁気ディスク等の磁気記録
媒体に対する高性能化の必要性が益々生じてきている。 即ち、記録密度特性の向上である。
2. Description of the Related Art In recent years, as magnetic recording and reproducing equipment has become smaller and lighter, there has been an increasing need for higher performance magnetic recording media such as magnetic tapes and magnetic disks. That is, the recording density characteristics are improved.

【0003】磁気記録媒体の記録密度特性を向上させる
為には、用いる磁性材料粒子粉末が出来るだけ高い保磁
力を有することである。この事実は、例えば、社団法人
電子通信学会「電子通信学会技術研究報告」MR77−
36(1978年発行)、第37頁の「磁気テープの記
録密度を上げるためには、テープに用いる磁性粉の保磁
力を大きくすることが必要である。」なる記載の通りで
ある。
In order to improve the recording density characteristics of a magnetic recording medium, it is important that the magnetic material particles used have as high a coercive force as possible. This fact can be seen, for example, in IEICE Technical Research Report MR77-
36 (published in 1978), page 37, "In order to increase the recording density of a magnetic tape, it is necessary to increase the coercive force of the magnetic powder used in the tape."

【0004】現在、高い保磁力を有する針状磁性酸化鉄
粒子粉末として所謂、Coドープ型の針状磁性酸化鉄粒
子と所謂、Co被着型の針状磁性酸化鉄粒子が知られて
おり、これら針状磁性酸化鉄粒子の保磁力は、Co量が
多くなる程高くなる傾向にある。前者は出発原料である
針状ゲータイト粒子の生成反応にあたり予めCo塩を添
加しておくことによりCo含有針状ゲータイト粒子を生
成させ、次いで、還元してCo含有針状マグネタイト粒
子とするか、必要により更に酸化してCo含有針状マグ
ヘマイト粒子とすることにより、後者は出発原料である
針状ゲータイト粒子を還元、又は必要により酸化して得
られた針状マグネタイト粒子又は針状マグヘマイト粒子
を前駆体粒子として該前駆体粒子をCo又はCo及びF
e2+で変成することにより得られる。
Currently, so-called Co-doped acicular magnetic iron oxide particles and so-called Co-coated acicular magnetic iron oxide particles are known as acicular magnetic iron oxide particles having high coercivity. The coercive force of these acicular magnetic iron oxide particles tends to increase as the amount of Co increases. In the former case, Co-containing acicular goethite particles are generated by adding Co salt in advance during the production reaction of acicular goethite particles, which are the starting materials, and then reduced to produce Co-containing acicular magnetite particles, or as necessary. The latter is further oxidized to Co-containing acicular maghemite particles by reducing the acicular goethite particles that are the starting material, or converting the acicular magnetite particles or acicular maghemite particles obtained by oxidizing the starting material into precursors. The precursor particles as particles are Co or Co and F.
Obtained by metamorphosis with e2+.

【0005】一方、磁気記録媒体は、記録、消去を繰り
返して行ない長期に亘り使用するものであるから、消去
特性が優れていることが要求されている。
On the other hand, magnetic recording media are required to have excellent erasing characteristics because they are used for long periods of time by repeated recording and erasing.

【0006】磁気記録媒体に対する上記のような要求を
満足させる為には、用いられる磁性酸化鉄粒子の消去特
性が優れていることが必要である。
In order to satisfy the above requirements for magnetic recording media, it is necessary that the magnetic iron oxide particles used have excellent erasing properties.

【0007】従来、Co被着型の針状磁性酸化鉄粒子の
諸特性を改良する為に、Co塩及びFe2+塩を分割し
て添加しCo化合物及びFe化合物を被着するものとし
ては、特公昭58−29605号公報、特公平1−14
176号公報、特開昭56−59629号公報、特開昭
59−151402号公報、特開昭61−10031号
公報及び特開昭61−212003号公報等に記載の方
法がある。
Conventionally, in order to improve various properties of Co-coated acicular magnetic iron oxide particles, a special method has been developed in which Co salt and Fe2+ salt are added separately to coat Co compound and Fe compound. Publication No. 58-29605, Special Publication No. 1-14
There are methods described in JP-A No. 176, JP-A-56-59629, JP-A-59-151402, JP-A-61-10031, and JP-A-61-212003.

【0008】また、Co塩と共にSi化合物を添加する
ものとしては、特開昭55−72007号公報及び特開
昭63−303817号公報等に記載の方法がある。
Furthermore, methods for adding a Si compound together with a Co salt include methods described in JP-A-55-72007 and JP-A-63-303817.

【0009】[0009]

【発明が解決しようとする課題】高い保磁力を有し、且
つ、消去特性が優れている針状磁性酸化鉄粒子は、現在
最も要求されているところであるが、上述した通りのC
oドープ型の針状磁性酸化鉄粒子は、高い保磁力を有す
るものであるが、一方、Coが結晶内に拡散する等に起
因して保磁力分布の拡がりが大きくなり、その結果、消
去特性が劣化するという欠点を有するものである。
[Problems to be Solved by the Invention] Acicular magnetic iron oxide particles having a high coercive force and excellent erasing properties are currently most in demand, but the above-mentioned C
O-doped acicular magnetic iron oxide particles have a high coercive force, but on the other hand, due to the diffusion of Co into the crystal, the coercive force distribution becomes wider, and as a result, the erasing property It has the disadvantage that it deteriorates.

【0010】この現象は、前出「電子通信学会技術研究
報告」の「Co固溶型(ドープ型)酸化鉄磁性粉は、保
磁力が熱的、経時的に変化しやすいため、テープにした
とき、転写及び消去特性が劣るという大きな欠点を有し
ている。これらの欠点は、室温でもCoイオンが結晶内
を動くことに起因する、と考えられている。」なる記載
の通りである。
[0010] This phenomenon is explained in the above-mentioned ``Technical Research Report of the Institute of Electronics and Communication Engineers'', which states, ``Co solid solution type (doped type) iron oxide magnetic powder has a coercive force that easily changes thermally and over time. When used, it has a major drawback of poor transfer and erasing properties.These drawbacks are thought to be caused by the movement of Co ions within the crystal even at room temperature."

【0011】また、上述した通りのCo被着型の針状磁
性酸化鉄粒子は、高い保磁力を有すると同時に、Coド
ープ型の針状磁性酸化鉄に比べ、消去特性が優れている
という特徴を有するものである。この現象は、前出「電
子通信学会技術研究報告」の「‥‥Coエピタキシャル
(Co被着型)酸化鉄磁性粉においては、二重構造にな
っているため、これらの欠点は解消され、熱的経時的に
も安定で、この磁性粉を使用したテープは、すぐれた転
写特性、消去特性を有する。‥‥」なる記載の通りであ
る。
[0011] Furthermore, the Co-coated acicular magnetic iron oxide particles as described above have a high coercive force and are also characterized in that they have superior erasing properties compared to Co-doped acicular magnetic iron oxide particles. It has the following. This phenomenon is explained in the above-mentioned ``IEICE Technical Research Report'' as ``...Co epitaxial (Co-adhered) iron oxide magnetic powder has a double structure, so these drawbacks are eliminated and heat resistance is reduced. It is stable over time, and tapes using this magnetic powder have excellent transfer and erasing properties.

【0012】しかしながら、近時、消去特性の改良に対
する要求はとどまるところがなく、上記Co被着型の針
状磁性酸化鉄粒子においても未だ、保磁力分布の拡がり
が大きく、消去特性が優れたものとは言い難いことが指
摘されている。
However, in recent years, there has been an unrelenting demand for improvement in erasing properties, and even the above-mentioned Co-coated acicular magnetic iron oxide particles still have a wide coercive force distribution and excellent erasing properties. It has been pointed out that it is difficult to say.

【0013】この事実は、例えば、特開昭61−174
26号公報の「‥‥上記γ−Fe2 O3 粒子を使用
した磁性粉にあっては、このγ−Fe2 O3 粒子が
微粒子になるにつれ抗磁力分布が広がり、さらにコバル
ト被着を行うとこの抗磁力分布はより一層広がる傾向に
あることがわかった。‥‥高密度記録を図るために上記
コバルト被着型γ−Fe2O3 粒子の微細化を進める
と、所定の抗磁力Hcは得られても、抗磁力分布の悪い
消去特性に劣る磁性粉しか得られない。‥‥」なる記載
の通りである。
[0013] This fact is, for example, disclosed in Japanese Patent Laid-Open No. 174-1983
Publication No. 26 states, ``In the magnetic powder using the above-mentioned γ-Fe2 O3 particles, the coercive force distribution broadens as the γ-Fe2 O3 particles become finer particles, and when cobalt is further deposited, this coercive force increases. It was found that the distribution tends to become even wider. When the cobalt-coated γ-Fe2O3 particles are made finer in order to achieve high-density recording, even if a predetermined coercive force Hc is obtained, the coercive force Hc becomes smaller. Only magnetic powder with poor magnetic force distribution and poor erasing properties can be obtained.''

【0014】そして、Co被着型の針状磁性酸化鉄粒子
の保磁力分布の拡がりはCo被着量が多くなる程大きく
なり、その結果、消去特性は劣化する傾向にあり、保磁
力の向上とは逆の相関関係にある。
The spread of the coercive force distribution of Co-coated acicular magnetic iron oxide particles increases as the amount of Co-coated increases, and as a result, the erasing characteristics tend to deteriorate, and the coercive force cannot be improved. There is an inverse correlation.

【0015】一方、ビデオ機器においては、通常、光で
走行テープの端末を検出する機構が採られているため使
用されるビデオテープの光透過率が高くなると誤作動が
発生する。しかしながら、現在最も多くビデオテープに
用いられているCo被着型γ−Fe2 O3 粒子粉末
の微粒子化が進むと光透過率が高くなるという課題をか
かえている。
On the other hand, since video equipment usually employs a mechanism for detecting the end of a running tape using light, malfunctions may occur if the light transmittance of the video tape used becomes high. However, as the Co-coated γ-Fe2O3 particles, which are currently most commonly used in videotapes, become finer, the light transmittance increases.

【0016】カーボンブラツク等の非磁性充填剤を多く
添加して光透過率を改善しようとする試みもなされてい
るが、カーボンブラック等の非磁性体を用いると高密度
記録化が阻害される。
Attempts have been made to improve the light transmittance by adding a large amount of non-magnetic filler such as carbon black, but the use of non-magnetic materials such as carbon black hinders high-density recording.

【0017】そこで、非磁性充填剤を添加することなく
光透過率を改善する方法として、黒色度に優れた針状マ
グネタイト粒子や針状ベルトライド化合物粒子の粒子表
面にCo被着した磁性酸化鉄粒子粉末が用いられるよう
になった。
Therefore, as a method for improving light transmittance without adding a non-magnetic filler, magnetic iron oxide coated with Co on the particle surface of acicular magnetite particles or acicular bertolide compound particles with excellent blackness was proposed. Particulate powders began to be used.

【0018】前述の針状マグネタイト粒子や針状ベルト
ライド化合物粒子の粒子表面にCo被着する技術手段は
周知であり、高い保磁力を有し、しかも、黒色度に優れ
た磁性酸化鉄粒子粉末であることもよく知られている。
The technical means of depositing Co on the particle surface of the acicular magnetite particles or acicular beltolide compound particles described above is well known, and magnetic iron oxide particles have a high coercive force and excellent blackness. It is also well known that

【0019】しかし、針状マグネタイト粒子及び針状ベ
ルトライド化合物粒子にCo被着した磁性酸化鉄粒子粉
末は、高い飽和磁化値と優れた電気抵抗が得られるとい
う利点があるものゝ、含まれるFe2+が徐々に酸化さ
れ磁気特性の経時的劣化が生起するという問題があり、
微粒子化する程その傾向は顕著である。
However, magnetic iron oxide particle powder in which Co is coated on acicular magnetite particles and acicular beltolide compound particles has the advantage of obtaining a high saturation magnetization value and excellent electrical resistance. There is a problem that the magnetic properties are gradually oxidized and the magnetic properties deteriorate over time.
This tendency becomes more pronounced as the particles become finer.

【0020】前掲の各公報に開示されているCo塩及び
Fe2+塩を分割して添加する技術手段によっても、消
去特性及び保磁力分布がいまだ不充分であり、前駆体粒
子に針状マグネタイト粒子や針状ベルトライド化合物粒
子を用いた場合の磁気特性の経時安定性も不充分である
Even with the technical means of dividing and adding Co salt and Fe2+ salt disclosed in the above-mentioned publications, the erasing characteristics and coercive force distribution are still insufficient, and the precursor particles are not mixed with acicular magnetite particles or The stability of magnetic properties over time when acicular bertolide compound particles are used is also insufficient.

【0021】また、特開昭63−303817号公報に
開示されているCo被着後にSi化合物などの被覆層を
形成かる技術手段によってもその効果は不充分である。 尚、特開昭57−72007号公報に開示されているC
o被着時にケイ酸化合物を添加する技術手段においては
、アルカリによるCo被着の一部がこわれるのを防ぐた
めに加熱後1時間後に投入するのが望ましいとされてお
り、後述するように本発明とその作用・効果が異なる。
[0021] Furthermore, even the technical means disclosed in JP-A-63-303817 in which a coating layer of a Si compound or the like is formed after depositing Co has insufficient effects. In addition, C disclosed in Japanese Patent Application Laid-Open No. 57-72007
o In the technical means of adding a silicic acid compound at the time of deposition, it is said that it is desirable to add it one hour after heating in order to prevent part of the Co deposition from being destroyed by alkali. and their actions and effects are different.

【0022】また、特開平1−290534号公報には
、Si化合物と同様の効果を奏することでよく用いられ
るAl塩の存在下にCo被着する技術手段が開示されて
いるが、Al塩がFe2+化合物の被着前或いは被着に
存在すると保磁力を著しく低下させるとしており、後述
するように本発明においてはFe2+を積極的に存在さ
せている点で作用・効果が異なる。
Furthermore, JP-A-1-290534 discloses a technical means of depositing Co in the presence of an Al salt, which is often used because it has the same effect as a Si compound. It is said that the presence of the Fe2+ compound before or during the deposition significantly reduces the coercive force, and as will be described later, the present invention differs in its action and effect in that Fe2+ is actively present.

【0023】そこで、本発明は、Co被着型の針状磁性
酸化鉄粒子の保磁力を維持しながら、消去特性と保磁力
分布を更に改良し、しかも、磁気的な経時安定性の向上
を図ることを技術的課題とするものである。
Therefore, the present invention further improves the erasing characteristics and coercive force distribution while maintaining the coercive force of Co-coated acicular magnetic iron oxide particles, and also improves the magnetic stability over time. The technical challenge is to achieve this goal.

【0024】[0024]

【課題を解決する為の手段】前述の技術的課題は、次の
通りの本発明によって達成できる。
[Means for Solving the Problems] The above-mentioned technical problems can be achieved by the present invention as follows.

【0025】即ち、本発明は、針状磁性酸化鉄粒子粉末
の水性分散液に非酸化性雰囲気下、60℃以下の温度で
Co塩水溶液を添加・混合し、この混合液に水酸化アル
カリ水溶液を加えてアルカリ性懸濁液とし、この懸濁液
を非酸化性雰囲気下、沸点以下の温度で加熱攪拌するこ
とにより前記針状磁性酸化鉄粒子の表面をCo化合物に
よって変成させ、次いで、当該懸濁液を60℃以下の温
度とした後、Fe2+塩水溶液を添加・混合し、非酸化
性雰囲気下、沸点以下の温度で加熱攪拌することにより
前記針状磁性酸化鉄粒子の表面を更にFe化合物によっ
て変成させ、次いで、当該懸濁液を60℃以下の温度と
した後、Co塩水溶液とSi化合物とを添加・混合し、
非酸化性雰囲気下、沸点以下の温度で加熱攪拌すること
により前記針状磁性酸化鉄粒子の表面の最上層をSiを
含むCo化合物によって変成させた後、濾別、水洗、乾
燥して針状磁性酸化鉄粒子粉末を得ることからなる磁気
記録用針状磁性酸化鉄粒子粉末の製造法、
That is, in the present invention, an aqueous Co salt solution is added to and mixed with an aqueous dispersion of acicular magnetic iron oxide particles at a temperature of 60° C. or less in a non-oxidizing atmosphere, and an aqueous alkali hydroxide solution is added to the mixed solution. is added to form an alkaline suspension, and this suspension is heated and stirred in a non-oxidizing atmosphere at a temperature below the boiling point to modify the surface of the acicular magnetic iron oxide particles with a Co compound. After bringing the temperature of the suspension to 60°C or lower, an aqueous Fe2+ salt solution is added and mixed, and the surface of the acicular magnetic iron oxide particles is further coated with Fe compounds by heating and stirring in a non-oxidizing atmosphere at a temperature below the boiling point. Then, after bringing the suspension to a temperature of 60 ° C. or less, adding and mixing a Co salt aqueous solution and a Si compound,
The top layer of the surface of the acicular magnetic iron oxide particles is modified with a Co compound containing Si by heating and stirring in a non-oxidizing atmosphere at a temperature below the boiling point, and then filtered, washed with water, and dried to form acicular magnetic iron oxide particles. A method for producing acicular magnetic iron oxide particles for magnetic recording, comprising obtaining magnetic iron oxide particles;

【0026】
針状磁性酸化鉄粒子粉末の水性分散液に非酸化性雰囲気
下、60℃以下の温度でCo塩水溶液とFe2+塩水溶
液又はCo塩水溶液とSi化合物もしくはCo塩水溶液
、Fe2+塩水溶液及びSi化合物とを添加・混合し、
この混合液に水酸化アルカリ水溶液を加えてアルカリ性
懸濁液とし、この懸濁液を非酸化性雰囲気下、沸点以下
の温度で加熱攪拌することにより前記針状磁性酸化鉄粒
子の表面をCo化合物とFe化合物又はSiを含むCo
化合物もしくはSiを含むCo化合物とFe化合物とに
よって変成させ、次いで、当該懸濁液を60℃以下の温
度とした後、Fe2+塩水溶液を添加・混合し、非酸化
性雰囲気下、沸点以下の温度で加熱攪拌することにより
前記針状磁性酸化鉄粒子の表面を更にFe化合物によっ
て変成させ、次いで、当該懸濁液を60℃以下の温度と
した後、Co塩水溶液とSi化合物とを添加・混合し、
非酸化性雰囲気下、沸点以下の温度で加熱攪拌すること
により前記針状磁性酸化鉄粒子の表面の最上層をSiを
含むCo化合物によって変成させた後、濾別、水洗、乾
燥して針状磁性酸化鉄粒子粉末を得ることからなる磁気
記録用針状磁性酸化鉄粒子粉末の製造法、
[0026]
Co salt aqueous solution and Fe2+ salt aqueous solution or Co salt aqueous solution and Si compound or Co salt aqueous solution, Fe2+ salt aqueous solution and Si compound are added to an aqueous dispersion of acicular magnetic iron oxide particle powder in a non-oxidizing atmosphere at a temperature of 60°C or less. Add and mix,
An aqueous alkali hydroxide solution is added to this mixed solution to form an alkaline suspension, and this suspension is heated and stirred in a non-oxidizing atmosphere at a temperature below the boiling point to coat the surface of the acicular magnetic iron oxide particles with a Co compound. and Co containing Fe compound or Si
compound or a Co compound containing Si and an Fe compound, and then the suspension is brought to a temperature of 60°C or lower, and then an aqueous Fe2+ salt solution is added and mixed, and the temperature is lowered to the boiling point in a non-oxidizing atmosphere. The surface of the acicular magnetic iron oxide particles is further modified with the Fe compound by heating and stirring, and then, after bringing the suspension to a temperature of 60 ° C. or less, an aqueous Co salt solution and a Si compound are added and mixed. death,
The top layer of the surface of the acicular magnetic iron oxide particles is modified with a Co compound containing Si by heating and stirring in a non-oxidizing atmosphere at a temperature below the boiling point, and then filtered, washed with water, and dried to form acicular magnetic iron oxide particles. A method for producing acicular magnetic iron oxide particles for magnetic recording, comprising obtaining magnetic iron oxide particles;

【0027】
針状磁性酸化鉄粒子粉末の水性分散液に非酸化性雰囲気
下、60℃以下の温度でCo塩水溶液を添加・混合し、
この混合液に水酸化アルカリ水溶液を加えてアルカリ性
懸濁液とし、この懸濁液を非酸化性雰囲気下、沸点以下
の温度で加熱攪拌することにより前記針状磁性酸化鉄粒
子の表面をCo化合物によって変成させ、次いで、当該
懸濁液を60℃以下の温度とした後、Fe2+塩水溶液
とCo塩水溶液又はFe2+塩水溶液とSi化合物もし
くはFe2+塩水溶液、Co塩水溶液及びSi化合物と
を添加・混合し、非酸化性雰囲気下、沸点以下の温度で
加熱攪拌することにより前記針状磁性酸化鉄粒子の表面
を更にFe化合物とCo化合物又はSiを含むFe化合
物もしくはSiを含むFe化合物とCo化合物とによっ
て変成させ、次いで、当該懸濁液を60℃以下の温度と
した後、Co塩水溶液とSi化合物とを添加・混合し、
非酸化性雰囲気下、沸点以下の温度で加熱攪拌すること
により前記針状磁性酸化鉄粒子の表面の最上層をSiを
含むCo化合物によって変成させた後、濾別、水洗、乾
燥して針状磁性酸化鉄粒子粉末を得ることからなる磁気
記録用針状磁性酸化鉄粒子粉末の製造法及び
[0027]
Adding and mixing a Co salt aqueous solution to an aqueous dispersion of acicular magnetic iron oxide particle powder at a temperature of 60 ° C. or less in a non-oxidizing atmosphere,
An aqueous alkali hydroxide solution is added to this mixed solution to form an alkaline suspension, and this suspension is heated and stirred in a non-oxidizing atmosphere at a temperature below the boiling point to coat the surface of the acicular magnetic iron oxide particles with a Co compound. Then, after bringing the suspension to a temperature of 60° C. or lower, an aqueous Fe2+ salt solution and an aqueous Co salt solution, or an aqueous Fe2+ salt solution and a Si compound, or an aqueous Fe2+ salt solution, an aqueous Co salt solution, and a Si compound are added and mixed. Then, by heating and stirring at a temperature below the boiling point in a non-oxidizing atmosphere, the surface of the acicular magnetic iron oxide particles is further coated with an Fe compound and a Co compound, or an Fe compound containing Si, or an Fe compound containing Si and a Co compound. Then, after bringing the suspension to a temperature of 60 ° C. or less, adding and mixing a Co salt aqueous solution and a Si compound,
The top layer of the surface of the acicular magnetic iron oxide particles is modified with a Co compound containing Si by heating and stirring in a non-oxidizing atmosphere at a temperature below the boiling point, and then filtered, washed with water, and dried to form acicular magnetic iron oxide particles. A method for producing acicular magnetic iron oxide particles for magnetic recording, which comprises obtaining magnetic iron oxide particles, and

【0028
】針状磁性酸化鉄粒子粉末の水性分散液に非酸化性雰囲
気下、60℃以下の温度でCo塩水溶液とFe2+塩水
溶液又はCo塩水溶液とSi化合物もしくはCo塩水溶
液、Fe2+塩水溶液及びSi化合物とを添加・混合し
、この混合液に水酸化アルカリ水溶液を加えてアルカリ
性懸濁液とし、この懸濁液を非酸化性雰囲気下、沸点以
下の温度で加熱攪拌することにより前記針状磁性酸化鉄
粒子の表面をCo化合物とFe化合物又はSiを含むC
o化合物もしくはSiを含むCo化合物とFe化合物と
によって変成させ、次いで、当該懸濁液を60℃以下の
温度とした後、Fe2+塩水溶液とCo塩水溶液又はF
e2+塩水溶液とSi化合物もしくはFe2+塩水溶液
、Co塩水溶液及びSi化合物とを添加・混合し、非酸
化性雰囲気下、沸点以下の温度で加熱攪拌することによ
り前記針状磁性酸化鉄粒子の表面を更にFe化合物とC
o化合物又はSiを含むFe化合物もしくはSiを含む
Fe化合物とCo化合物とによって変成させ、次いで、
当該懸濁液を60℃以下の温度とした後、Co塩水溶液
とSi化合物とを添加・混合し、非酸化性雰囲気下、沸
点以下の温度で加熱攪拌することにより前記針状磁性酸
化鉄粒子の表面の最上層をSiを含むCo化合物によっ
て変成させた後、濾別、水洗、乾燥して針状磁性酸化鉄
粒子粉末を得ることからなる磁気記録用針状磁性酸化鉄
粒子粉末の製造法である。
0028
] Add Co salt aqueous solution and Fe2+ salt aqueous solution or Co salt aqueous solution and Si compound or Co salt aqueous solution, Fe2+ salt aqueous solution and Si compound to an aqueous dispersion of acicular magnetic iron oxide particle powder in a non-oxidizing atmosphere at a temperature of 60°C or less. The above-mentioned acicular magnetic oxidation agent is added and mixed, and an aqueous alkali hydroxide solution is added to this mixed solution to form an alkaline suspension, and this suspension is heated and stirred in a non-oxidizing atmosphere at a temperature below the boiling point. The surface of the iron particles is coated with Co compound and Fe compound or C containing Si.
o compound or a Co compound containing Si and an Fe compound, and then, after the suspension is brought to a temperature of 60°C or less, an aqueous Fe2+ salt solution and an aqueous Co salt solution or an F
By adding and mixing the e2+ salt aqueous solution and the Si compound or the Fe2+ salt aqueous solution, the Co salt aqueous solution, and the Si compound, and heating and stirring in a non-oxidizing atmosphere at a temperature below the boiling point, the surface of the acicular magnetic iron oxide particles is Furthermore, Fe compound and C
o compound or a Fe compound containing Si or a Fe compound containing Si and a Co compound, and then
After bringing the temperature of the suspension to 60° C. or lower, a Co salt aqueous solution and a Si compound are added and mixed, and the acicular magnetic iron oxide particles are heated and stirred in a non-oxidizing atmosphere at a temperature below the boiling point. A method for producing acicular magnetic iron oxide particle powder for magnetic recording, which comprises modifying the uppermost layer of the surface with a Co compound containing Si, followed by filtering, washing with water, and drying to obtain acicular magnetic iron oxide particle powder. It is.

【0029】次に、本発明実施にあたっての諸条件につ
いて述べる。
Next, various conditions for implementing the present invention will be described.

【0030】本発明における前駆体とする針状磁性酸化
鉄粒子は、針状マグヘマイト粒子、針状マグネタイト粒
子、マグヘマイトとマグネタイトとの中間酸化物である
針状ベルトライド化合物粒子及びこれらにNi、Si、
Al、Zn、P、Zr、Ba、Sr、Ca、Pb等の1
種又は2種以上を含む粒子を用いることもできる。
The acicular magnetic iron oxide particles used as the precursor in the present invention include acicular maghemite particles, acicular magnetite particles, acicular bertolide compound particles which are intermediate oxides between maghemite and magnetite, and these particles containing Ni and Si. ,
1 such as Al, Zn, P, Zr, Ba, Sr, Ca, Pb, etc.
Particles containing a species or two or more species can also be used.

【0031】本発明におけるCo塩水溶液としては、硫
酸コバルト、塩化コバルト、硝酸コバルト等の水溶液を
使用することができる。
As the Co salt aqueous solution in the present invention, an aqueous solution of cobalt sulfate, cobalt chloride, cobalt nitrate, etc. can be used.

【0032】本発明におけるCo塩水溶液の添加量は、
前駆体粒子に対しCo換算で0.1〜15.0重量%で
あり、好ましくは0.1〜10.0重量%である。0.
1重量%未満の場合には、Co変成効果が顕著に現れな
い。15.0重量%を越える場合には、得られる針状磁
性酸化鉄粒子の保磁力分布が大きくなり、消去特性の改
良が困難となる。
[0032] The amount of Co salt aqueous solution added in the present invention is:
The amount is 0.1 to 15.0% by weight, preferably 0.1 to 10.0% by weight, based on Co, based on the precursor particles. 0.
If it is less than 1% by weight, the Co modification effect will not be noticeable. If it exceeds 15.0% by weight, the coercive force distribution of the obtained acicular magnetic iron oxide particles becomes large, making it difficult to improve the erasing characteristics.

【0033】Co塩水溶液を分割して添加する場合の総
添加量は上記範囲内であって、添加割合は任意に選択す
ることができるが、上層のCo量が下層のCo量より多
い方が良く、その比率は、2〜20倍程度であり、好ま
しくは3〜15倍である。2倍未満の場合には、得られ
る針状磁性酸化鉄粒子の経時安定性が悪くなり、20倍
を越える場合には、高い保磁力が得られなくなり、また
、粒子表面に変成させるFe2+化合物が相対的に少な
くなるので電気抵抗が高くなり好ましくない。
[0033] When the Co salt aqueous solution is added in portions, the total amount added is within the above range, and the addition ratio can be selected arbitrarily, but it is better if the amount of Co in the upper layer is larger than the amount of Co in the lower layer. The ratio is preferably about 2 to 20 times, preferably 3 to 15 times. If it is less than 2 times, the stability of the obtained acicular magnetic iron oxide particles over time will be poor, and if it is more than 20 times, it will not be possible to obtain a high coercive force, and the Fe2+ compound to be transformed on the particle surface will be Since the amount is relatively small, the electrical resistance becomes high, which is not preferable.

【0034】本発明におけるFe2+塩水溶液としては
、硫酸第一鉄、塩化第一鉄等の水溶液を使用することが
できる。
As the Fe2+ salt aqueous solution in the present invention, an aqueous solution of ferrous sulfate, ferrous chloride, etc. can be used.

【0035】Fe2+塩水溶液の添加量は、前駆体粒子
に対しFe換算で0.1〜15.0重量%である。0.
1重量%未満の場合には、保磁力向上の効果が低くなり
、また電気抵抗が上がる。15.0重量%を越える場合
には、得られる針状磁性酸化鉄粒子の保磁力分布が大き
くなり、消去特性の改良が困難となる。
The amount of the Fe2+ salt aqueous solution added is 0.1 to 15.0% by weight in terms of Fe based on the precursor particles. 0.
If it is less than 1% by weight, the effect of improving coercive force will be low and the electrical resistance will increase. If it exceeds 15.0% by weight, the coercive force distribution of the obtained acicular magnetic iron oxide particles becomes large, making it difficult to improve the erasing characteristics.

【0036】Fe2+塩水溶液は、1度に添加してもよ
く、または、分割して添加してもよい。その場合の総添
加量は、上記範囲内であって、その添加割合は任意に選
択することができる。
[0036] The aqueous Fe2+ salt solution may be added at once or may be added in portions. In that case, the total amount added is within the above range, and the addition ratio can be arbitrarily selected.

【0037】本発明における水酸化アルカリ水溶液とし
ては、水酸化ナトリウム、水酸化カリウム、アンモニア
水等の水溶液を使用することができる。
As the aqueous alkali hydroxide solution in the present invention, aqueous solutions of sodium hydroxide, potassium hydroxide, aqueous ammonia, etc. can be used.

【0038】水酸化アルカリ水溶液添加後のOH基濃度
は、0.05〜3.0mol/lであることが好ましい
。0.05mol/l未満の場合には、変成が充分生起
しない。3.0mol/lを越える場合には、水酸化コ
バルトが溶解しはじめるため好ましくない。
The OH group concentration after addition of the aqueous alkali hydroxide solution is preferably 0.05 to 3.0 mol/l. If it is less than 0.05 mol/l, metamorphosis will not occur sufficiently. If it exceeds 3.0 mol/l, cobalt hydroxide starts to dissolve, which is not preferable.

【0039】尚、Co塩及びFe2+塩などを分割添加
して被着処理を行なう際に、被着処理条件を維持するた
めに前記添加量に相当する水酸化アルカリ水溶液を追加
して添加してもよい。
[0039] When carrying out deposition treatment by adding Co salt, Fe2+ salt, etc. in portions, an aqueous alkali hydroxide solution corresponding to the above addition amount is additionally added in order to maintain the deposition treatment conditions. Good too.

【0040】本発明におけるSi化合物としては、水ガ
ラス、コロイダルシリカ、ケイ酸ナトリウム、ケイ酸カ
リウム、二酸化ケイ素等を使用することができる。
As the Si compound in the present invention, water glass, colloidal silica, sodium silicate, potassium silicate, silicon dioxide, etc. can be used.

【0041】Si化合物の添加量は、前駆体粒子に対し
SiO2 換算で0.01〜2.00重量%であり、好
ましくは0.05〜1.00重量%である。0.01重
量%未満の場合には、本発明の効果が得られず、2.0
0重量%を越える場合には、被着反応を阻害するととも
に高い保磁力が得られなくなる。
The amount of the Si compound added is 0.01 to 2.00% by weight, preferably 0.05 to 1.00% by weight, based on SiO2 based on the precursor particles. If it is less than 0.01% by weight, the effect of the present invention cannot be obtained, and the
If it exceeds 0% by weight, the adhesion reaction will be inhibited and high coercive force will not be obtained.

【0042】Si化合物の添加は後述するように前駆体
の粒子表面以外にCoフェライトが析出するのを抑制す
るために行なうのであるから1度に添加してもよいが、
Co塩の反応温度にあわせて分割添加するのが好ましい
。その場合の総添加量は上記範囲内であって、その目安
としては、懸濁液の温度が60℃以下の場合には、前記
前駆体粒子に対しSiO2 換算で0.05〜0.50
重量%が好ましく、また、60℃を越え沸点以下の場合
には、0.10〜1.00重量%が好ましい。何度かに
分けて被着を繰り返す場合においても、その総添加量が
2.00重量%以下とすることが望ましい。
As will be described later, the Si compound is added to suppress the precipitation of Co ferrite on surfaces other than the particle surface of the precursor, so it may be added all at once.
It is preferable to add the Co salt in portions depending on the reaction temperature of the Co salt. In that case, the total amount added is within the above range, and as a guide, when the temperature of the suspension is 60°C or less, 0.05 to 0.50 in terms of SiO2 is added to the precursor particles.
% by weight is preferred, and when the temperature exceeds 60°C and is below the boiling point, 0.10 to 1.00% by weight is preferred. Even when the coating is repeated several times, it is desirable that the total amount added be 2.00% by weight or less.

【0043】尚、Co塩水溶液、Fe2+塩水溶液及び
水酸化アルカリ水溶液とを添加する順序は、どちらが先
でも、また同時であってもよい。
The Co salt aqueous solution, the Fe2+ salt aqueous solution, and the alkali hydroxide aqueous solution may be added in any order or at the same time.

【0044】また、Si化合物を添加する順序は、特に
なくCo塩及びFe2+塩が前駆体の粒子表面以外にC
oフェライトが析出するのを抑制するためであるから前
記処理温度を目安に適度に行なえばよい。
Furthermore, there is no particular order in which the Si compounds are added;
The purpose of this treatment is to suppress the precipitation of o-ferrite, so the treatment temperature may be adjusted appropriately using the above treatment temperature as a guide.

【0045】本発明における前駆体粒子の懸濁液にCo
塩水溶液、Fe2+塩水溶液及び水酸化アルカリ水溶液
を添加・混合する場合の各温度は60℃以下で行ない、
好ましくは40℃以下である。60℃以下の温度するの
は、急激な反応を抑制してCo化合物及びFe化合物が
水酸化アルカリ水溶液と充分に混合してそれぞれCo(
OH)2 及びFe(OH)2 のコロイドを生成させ
た後、前駆体の粒子表面に変成させて高い保磁力と優れ
た保磁力分布を得るためである。
[0045] Co is added to the suspension of precursor particles in the present invention.
When adding and mixing the salt aqueous solution, Fe2+ salt aqueous solution and alkali hydroxide aqueous solution, each temperature is 60°C or less,
Preferably it is 40°C or lower. The reason for keeping the temperature below 60°C is to suppress rapid reactions and ensure that the Co compound and Fe compound are sufficiently mixed with the aqueous alkali hydroxide solution to form Co(
This is to obtain a high coercive force and an excellent coercive force distribution by generating colloids of OH)2 and Fe(OH)2 and then transmuting them onto the particle surface of the precursor.

【0046】この場合の攪拌時間は、30〜120分間
の範囲から選定することが好ましい。30分間未満の場
合には、充分に混合させることが出来ないおそれがあり
、また、120分間を越えても工業的にその意義がない
[0046] In this case, the stirring time is preferably selected from a range of 30 to 120 minutes. If the time is less than 30 minutes, sufficient mixing may not be possible, and if the time is more than 120 minutes, there is no industrial significance.

【0047】本発明における前駆体の粒子表面にCo化
合物及びFe化合物とを強固に変成させる各加熱攪拌は
、沸点以下の温度で行なう。沸点を越える場合にも、被
着処理することはできるがオートクレーブなどの装置を
必要とするため工業的には沸点以下で行なうのが好まし
い。また、被着処理は60℃以下でもできるが、被着反
応が著しく遅くなり、充分な磁気特性をひきだせなくな
るので60℃を越える温度で行なうのが好ましい。
[0047] In the present invention, each heating and stirring process for strongly modifying the Co compound and Fe compound on the particle surface of the precursor is carried out at a temperature below the boiling point. Even if the temperature exceeds the boiling point, it is possible to carry out the deposition treatment, but since equipment such as an autoclave is required, industrially it is preferable to carry out the process at a temperature below the boiling point. Although the adhesion process can be carried out at temperatures below 60°C, it is preferable to carry out the process at temperatures above 60°C since the adhesion reaction becomes extremely slow and sufficient magnetic properties cannot be obtained.

【0048】この場合の攪拌時間は30〜900分間の
範囲から選定することが好ましい。30分間未満の場合
には、被着が充分でなく、また、900分間を越えても
工業的に意義がない。実用上、望ましい範囲は、30〜
600分間である。
[0048] In this case, the stirring time is preferably selected from a range of 30 to 900 minutes. If the duration is less than 30 minutes, the adhesion will not be sufficient, and if it exceeds 900 minutes, there is no industrial significance. Practically, the desirable range is 30 to
It is 600 minutes.

【0049】本発明における各添加、各攪拌処理は、非
酸化性雰囲気下で行なう。非酸化性雰囲気下でFe2+
の酸化を抑制して、被着処理による高い保磁力と優れた
保磁力分布を得るためである。尚、非酸化性雰囲気は、
N2 、Arガス等不活性ガス流下で行なうことが望ま
しい。
[0049] In the present invention, each addition and each stirring treatment are carried out under a non-oxidizing atmosphere. Fe2+ under non-oxidizing atmosphere
This is to suppress the oxidation of the metal and obtain high coercive force and excellent coercive force distribution through the adhesion treatment. In addition, the non-oxidizing atmosphere is
It is desirable to carry out the process under a flow of an inert gas such as N2 or Ar gas.

【0050】[0050]

【作用】前述したように、従来のCo被着型の針状磁性
酸化鉄粒子は、保磁力分布の拡がりが大きく、消去特性
が優れたものとは言い難い。また、Fe2+イオンの多
く含まれた黒色度に優れた針状磁性酸化鉄粒子の場合は
磁気的な経時安定性に問題がある。
[Function] As described above, the conventional Co-coated acicular magnetic iron oxide particles have a wide coercive force distribution and cannot be said to have excellent erasing characteristics. Further, in the case of acicular magnetic iron oxide particles containing a large amount of Fe2+ ions and having excellent blackness, there is a problem in magnetic stability over time.

【0051】本発明者は、従来の技術手段では前駆体粒
子の一個一個の粒子表面にCo及びFeが均一に被着せ
ず、しかも、前駆体粒子とは別の高い保磁力を有する微
細なCoフェライトが生起するために保磁力分布が大き
くなり、消去特性も悪くなるものと考えた。
[0051] The present inventor discovered that Co and Fe could not be uniformly deposited on the surfaces of individual precursor particles using conventional technical means, and that fine Co and Fe having a high coercive force, which is different from the precursor particles, It was thought that the coercive force distribution would increase due to the formation of ferrite, and the erasing characteristics would also deteriorate.

【0052】また、磁気的な経時安定性は、得られたC
o被着型の針状磁性酸化鉄粒子の粒子表面近傍にFe2
+が多く存在すると空気中の酸素に触れて酸化されてF
e3+となり粒子内部にまでFe3+が浸透して磁気的
な経時変化が進むためと考えた。
In addition, the magnetic stability over time was determined by the obtained C
o Fe2 is present near the particle surface of the adhering type acicular magnetic iron oxide particles.
If there is a large amount of +, it will be oxidized by contact with oxygen in the air and become F.
It is thought that this is because Fe3+ penetrates into the inside of the particles to become e3+, and the magnetic change over time progresses.

【0053】そこで、Co及びFeの被着状態を制御で
きる方法について検討を進め、本発明に到達した。
[0053] Therefore, we conducted studies on a method that can control the deposition state of Co and Fe, and arrived at the present invention.

【0054】即ち、懸濁液中に適度のSi化合物を存在
させることによりCo塩及びFe2+塩の急激な反応を
抑制することができるため、充分に混合してCo(OH
)2 及びFe(OH)2 のコロイドを生成した後に
前駆体粒子の粒子表面にCo及びFeを均一に被着する
ことができ、また、前駆体粒子の粒子表面以外に独立し
たCoフェライトを生成することを防ぐことができた。 その結果、高い保磁力を維持しながら、消去特性と保磁
力分布を改良することができた。
That is, by having an appropriate amount of Si compound in the suspension, the rapid reaction of Co salt and Fe2+ salt can be suppressed.
)2 and Fe(OH)2 colloids are produced, Co and Fe can be uniformly deposited on the particle surfaces of the precursor particles, and independent Co ferrite can be produced on surfaces other than the particle surfaces of the precursor particles. I was able to prevent it from happening. As a result, it was possible to improve the erasing characteristics and coercive force distribution while maintaining a high coercive force.

【0055】懸濁液中にSi化合物を存在させるとなぜ
急激な反応が抑制できるのかは不明であるが、本発明者
は、Co(OH)2 又はFe(OH)2 とSiイオ
ンとが反応して錯体化合物を生成し、その後に被着反応
が生起するために反応を抑制することができたものと考
えている。
[0055] Although it is unclear why the presence of a Si compound in the suspension can suppress the rapid reaction, the present inventor has found that Co(OH)2 or Fe(OH)2 and Si ions react. It is believed that the reaction was able to be suppressed because a complex compound was produced and then a deposition reaction occurred.

【0056】また、前駆体として針状マグネタイト粒子
や針状ベルトライド化合物粒子を用いたり、高い保磁力
と黒色度の向上をはかるためにFe2+塩を多く添加す
る場合においてもSi化合物の存在下で変成処理したこ
とにより得られるSiを含むCo化合物又はSiを含む
Fe化合物もしくはSiを含むCo化合物とFe化合物
との被着層としたことにより磁気的な経時安定性も良く
なり、更に、最上層の被着をSiを含むCo化合物とし
た時には、空気中の酸素とFe2+が触れ難くなり、そ
の効果は飛躍的に向上した。
Furthermore, even when using acicular magnetite particles or acicular beltolide compound particles as a precursor, or when adding a large amount of Fe2+ salt in order to improve coercive force and blackness, in the presence of Si compounds, The magnetic stability over time is improved by using a Co compound containing Si obtained through modification treatment, an Fe compound containing Si, or a Co compound containing Si and an Fe compound as an adhesion layer. When a Co compound containing Si was used as the coating material, it became difficult for Fe2+ to come into contact with oxygen in the air, and the effect was dramatically improved.

【0057】これらの優れた効果は、Co塩及びFe2
+塩をそれぞれ2回以上に分割して添加する場合におい
ても得られる。
These excellent effects are due to Co salt and Fe2
It can also be obtained when +salt is added in two or more portions.

【0058】本発明は、従来、Si化合物を添加して被
着を行なうと高い保磁力を阻害するばかりでなく、被着
反応そのものにさまざまな悪影響を及ぼすと考えられて
きた定説をくつがえす画期的なものといえる。
The present invention is a breakthrough that overturns the conventional wisdom that adding a Si compound to deposition not only inhibits high coercive force but also has various negative effects on the deposition reaction itself. It can be said that it is something like that.

【0059】尚、本発明によるCo被着後の針状磁性酸
化鉄粒子粉末にSi、Al、Ca、Ti、V、Mn、N
i、Zn、P、Zrなどの1種又は2種の化合物を被覆
処理しても本発明の効果を妨げることはなく、むしろ、
さらに磁気的な経時安定性を向上させたり、結合剤樹脂
との分散性向上などの効果が期待できる。
It should be noted that Si, Al, Ca, Ti, V, Mn, N are added to the acicular magnetic iron oxide particle powder after coating Co according to the present invention.
Coating treatment with one or two compounds such as i, Zn, P, and Zr does not impede the effects of the present invention; rather,
Furthermore, effects such as improved magnetic stability over time and improved dispersibility with the binder resin can be expected.

【0060】[0060]

【実施例】次に、実施例並びに比較例により、本発明を
説明する。
[Examples] Next, the present invention will be explained with reference to Examples and Comparative Examples.

【0061】尚、以下の実施例並びに比較例における粒
子の平均径は、電子顕微鏡写真から測定した数値の平均
値であり、また、比表面積はBET法により測定した値
で示した。針状磁性酸化鉄粒子粉末の磁気特性は、「振
動試料型磁力計VSM−3S−15」(東英工業(株)
製)を使用し、外部磁場10KOeまでかけて測定した
値である。
[0061] In the following Examples and Comparative Examples, the average diameter of the particles is the average value of numerical values measured from electron micrographs, and the specific surface area is shown as the value measured by the BET method. The magnetic properties of the acicular magnetic iron oxide particles were measured using a "vibrating sample magnetometer VSM-3S-15" (Toei Kogyo Co., Ltd.).
These are the values measured using an external magnetic field of up to 10 KOe.

【0062】Fe2+の含有量の測定は、磁性酸化鉄粒
子粉末をフラスコに投入し、不活性ガスで置換し通気し
ながら硫酸と燐酸との混酸を添加・加熱溶解した後、当
該溶液中のFe2+を酸化還元滴定法により求めた。
[0062] To measure the content of Fe2+, put the magnetic iron oxide particles into a flask, replace with inert gas, add a mixed acid of sulfuric acid and phosphoric acid while aerating, heat and dissolve, and then measure the Fe2+ content in the solution. was determined by redox titration method.

【0063】消去特性は、社団法人粉体粉末冶金協会「
昭和61年春季大会講演概要集」の第152〜153頁
に記載の「磁性粉の消去磁化測定法」に従って測定した
値で示した。即ち、消去特性は、試料に直流磁界10K
Oeを印加した後、残留磁化Mrを測定し、次に、消去
装置にセットして消去磁界を800Oeから零まで印加
させた後、残留磁化Meを測定し、20logMe/M
r(dB)の値を求め、実測値を得た。消去特性の値は
、保磁力値と密接な関係があり、保磁力値が高くなる程
消去特性が劣化する傾向がある為、上記実測値を保磁力
700Oeにおける消去特性値に補正して示した。
[0063] The erasing property is determined by the Powder Metallurgy Association of Japan.
The values are shown as values measured according to the ``Measurement method for erasure magnetization of magnetic powder'' described on pages 152-153 of ``Collection of Abstracts of Lectures at the 1986 Spring Conference.'' That is, the erasing characteristic is determined by applying a DC magnetic field of 10K to the sample.
After applying Oe, the residual magnetization Mr was measured, and then the eraser was set in an eraser and an erase magnetic field was applied from 800 Oe to zero, and the residual magnetization Me was measured.
The value of r (dB) was determined and an actual value was obtained. The value of the erase characteristic is closely related to the coercive force value, and the higher the coercive force value, the worse the erase characteristic tends to be. Therefore, the above measured value was corrected to the erase characteristic value at a coercive force of 700 Oe. .

【0064】磁気特性の経時安定性を示すΔHcは、温
度60℃、相対湿度90%の恒温槽に2週間放置した後
に保磁力Hcを測定し、初期のHc値を差し引いた値で
ある。
ΔHc, which indicates the stability of magnetic properties over time, is the value obtained by measuring the coercive force Hc after leaving the sample in a constant temperature bath at a temperature of 60° C. and a relative humidity of 90% for two weeks, and subtracting the initial Hc value.

【0065】保磁力分布(S.F.D.)の測定はシー
ト試料片を用い、前記磁気測定機の微分回路を使用して
、保磁力の微分曲線を得、この曲線の半値巾を測定し、
この値のピーク値の保磁力で除することにより求めた。
To measure the coercive force distribution (S.F.D.), use a sheet sample piece, use the differential circuit of the magnetic measuring machine to obtain a differential curve of coercive force, and measure the half-width of this curve. death,
It was calculated by dividing this value by the coercive force of the peak value.

【0066】シート状試料片は、140ccのガラスビ
ンに磁性酸化鉄粒子粉末、樹脂及び溶剤を下記の割合で
入れた後、ペイントコンディショナーで2時間混合分散
を行うことにより調整した磁性塗料を厚さ25μmのポ
リエチレンテレフタレートフィルム上にアプリケーター
を用いて40μmの厚さに塗布し、次いで、1900G
aussの磁場中で配向させ、乾燥させることにより得
た。
[0066] The sheet-like sample piece was prepared by placing magnetic iron oxide particles, resin, and solvent in a 140 cc glass bottle in the proportions shown below, and then mixing and dispersing the mixture with paint conditioner for 2 hours. using an applicator to a thickness of 40 μm on a polyethylene terephthalate film of 1900G.
It was obtained by orienting it in the magnetic field of AUSS and drying it.

【0067】   1.5mmφガラスビーズ           
               100重量部  磁性
酸化鉄粒子粉末                  
                15重量部  塩化
ビニル−酢酸ビニル共重合体樹脂          
          3重量部  ニトリルゴム   
                         
        0.75重量部  シクロヘキサノン
                         
       11.5重量部  メチルエチルケトン
                         
     11.5重量部  トルエン       
                         
        11.5重量部  レシチン    
                         
           0.03重量部  リン酸エス
テル(ガファック  RE−610)      0.
03重量部
1.5mmφ glass beads
100 parts by weight magnetic iron oxide particle powder
15 parts by weight Vinyl chloride-vinyl acetate copolymer resin
3 parts by weight Nitrile rubber

0.75 parts by weight cyclohexanone
11.5 parts by weight Methyl ethyl ketone
11.5 parts by weight toluene

11.5 parts by weight lecithin

0.03 parts by weight Phosphate ester (Gafac RE-610) 0.
03 parts by weight

【0068】実施例1 前駆体粒子として針状マグネタイト粒子粉末(平均長軸
径0.19μm、軸比(長軸径/短軸径)8.0、BE
T比表面積32m2 /g、保磁力400Oe、飽和磁
化値80.5emu/g、Fe2+18.7重量%)8
00gを3200mlの水に分散して得られた水性分散
液に、2.0mol/lのCoSO4 水溶液67.9
ml(前駆体粒子に対しCo換算で1.0重量%に該当
する。)を添加・混合し、、N2 ガスを流して非酸化
性雰囲気とした上で、この混合液の温度を30℃とした
。以後、非酸化性雰囲気下で処理した。
Example 1 Acicular magnetite particle powder (average major axis diameter 0.19 μm, axial ratio (major axis diameter/minor axis diameter) 8.0, BE
T specific surface area 32m2/g, coercive force 400Oe, saturation magnetization value 80.5emu/g, Fe2+18.7% by weight)8
00 g in 3200 ml of water to obtain an aqueous dispersion, add 2.0 mol/l CoSO4 aqueous solution 67.9
ml (corresponding to 1.0% by weight in terms of Co relative to the precursor particles) was added and mixed, and after flowing N2 gas to create a non-oxidizing atmosphere, the temperature of this mixed solution was set to 30°C. did. Thereafter, it was treated under a non-oxidizing atmosphere.

【0069】上記混合液に18mol/lのNaOH水
溶液1230mlを加え、OH基濃度が1.5mol/
lの懸濁液とし、40℃の温度で10分間攪拌した後、
更に1.723mol/lのFeSO4 水溶液466
ml(前駆体粒子に対しFe換算で5.6重量%に相当
する。)を加え、温度を40℃とし、添加後30分間攪
拌処理を続け、黒褐色沈澱粒子を生成させた。
[0069] 1230 ml of 18 mol/l NaOH aqueous solution was added to the above mixture, and the OH group concentration was 1.5 mol/l.
After stirring for 10 minutes at a temperature of 40°C,
Furthermore, 1.723 mol/l FeSO4 aqueous solution 466
ml (corresponding to 5.6% by weight in terms of Fe based on the precursor particles) was added, the temperature was set at 40° C., and stirring was continued for 30 minutes after the addition to form blackish brown precipitated particles.

【0070】次いで、黒色沈澱粒子を2.0mol/l
のCoSO4 水溶液176.5ml(前駆体粒子に対
しCo換算で2.6重量%に該当する。)と3号水ガラ
ス3.2g(前駆体粒子に対しSiO2 換算で0.1
14重量%に該当する。)と水とを加え全容量を130
00mlとした。引き続き40℃の温度で30分間攪拌
を続け、更に前記3号水ガラス8.0g(前駆体粒子に
対しSiO2 が0.285重量%に該当する。)を加
えながら98℃に昇温した。昇温後、360分間保持し
加熱攪拌して黒色沈澱粒子を生成させた。
Next, black precipitate particles were added at 2.0 mol/l.
176.5 ml of CoSO4 aqueous solution (corresponding to 2.6% by weight in terms of Co based on the precursor particles) and 3.2 g of No. 3 water glass (0.1% in terms of SiO2 based on the precursor particles)
This corresponds to 14% by weight. ) and water to bring the total volume to 130.
00ml. Subsequently, stirring was continued for 30 minutes at a temperature of 40°C, and the temperature was raised to 98°C while adding 8.0 g of the above-mentioned No. 3 water glass (corresponding to 0.285% by weight of SiO2 based on the precursor particles). After raising the temperature, the mixture was maintained for 360 minutes and stirred under heating to generate black precipitated particles.

【0071】生成された黒色沈澱粒子を常法により、濾
別、水洗、乾燥して、黒色粒子粉末を得た。
The produced black precipitated particles were filtered, washed with water, and dried in a conventional manner to obtain black particle powder.

【0072】得られた黒色粒子粉末はCo被着型の針状
磁性酸化鉄粒子粉末であり、平均長軸径0.20μm、
軸比(長軸径/短軸径)7.5、保磁力750Oe、飽
和磁化値84.4emu/g、Fe2+含有量17.8
重量%であった。また、消去特性は54.3dBであり
、ΔHcは−22Oeと経時劣化の少ないものであった
The obtained black particles are Co-coated acicular magnetic iron oxide particles, with an average major axis diameter of 0.20 μm,
Axial ratio (long axis diameter/short axis diameter) 7.5, coercive force 750 Oe, saturation magnetization value 84.4 emu/g, Fe2+ content 17.8
% by weight. Further, the erasing characteristic was 54.3 dB, and ΔHc was -22 Oe, which showed little deterioration over time.

【0073】得られたCo被着型磁性酸化鉄粒子粉末を
用いて、シート試料片を作製して求めたシート特性は、
保磁力770Oe、角型比(Br/Bm)0.811、
保磁力分布(S.F.D.)0.422、電気抵抗1.
6×109Ω/sqであった。
[0073] Using the obtained Co-coated magnetic iron oxide particle powder, a sheet sample was prepared and the sheet properties were determined as follows:
Coercive force 770Oe, squareness ratio (Br/Bm) 0.811,
Coercive force distribution (S.F.D.) 0.422, electrical resistance 1.
It was 6×10 9 Ω/sq.

【0074】実施例2〜10、比較例1〜4前駆体粒子
の種類、Co塩水溶液の量及び添加時期、Fe2+水溶
液の量及び添加時期、Si化合物の量及び添加時期、水
酸化アルカリ水溶液のOH基濃度、添加時及び加熱攪拌
時の温度並びに添加攪拌時間及び加熱攪拌時間を種々変
化させた以外は、実施例1と同様にしてCo被着型の針
状磁性酸化鉄粒子粉末を得た。
Examples 2 to 10, Comparative Examples 1 to 4 Types of precursor particles, amount and timing of addition of aqueous Co salt solution, amount and timing of addition of aqueous Fe2+ solution, amount and timing of addition of Si compound, aqueous alkali hydroxide solution Co-coated acicular magnetic iron oxide particle powder was obtained in the same manner as in Example 1, except that the OH group concentration, the temperature during addition and heating stirring, and the addition stirring time and heating stirring time were varied. .

【0075】この時の主要製造条件及び諸特性を表1乃
至表3に示す。
[0075] The main manufacturing conditions and various properties at this time are shown in Tables 1 to 3.

【0076】[0076]

【表1】[Table 1]

【0077】[0077]

【表2】[Table 2]

【0078】[0078]

【表3】[Table 3]

【0079】[0079]

【発明の効果】本発明によって製造されたCo被着型の
針状磁性酸化鉄粒子粉末は、前出実施例に示した通り、
高い保磁力を有し、且つ、消去特性と保磁力分布に優れ
、しかも、磁気的な経時安定性が良いので高密度記録用
として好適である。
[Effects of the Invention] The Co-coated acicular magnetic iron oxide particles produced according to the present invention have the following properties as shown in the above examples:
It has high coercive force, excellent erasing characteristics and coercive force distribution, and good magnetic stability over time, making it suitable for high-density recording.

Claims (4)

【特許請求の範囲】[Claims] 【請求項1】  針状磁性酸化鉄粒子粉末の水性分散液
に非酸化性雰囲気下、60℃以下の温度でCo塩水溶液
を添加・混合し、この混合液に水酸化アルカリ水溶液を
加えてアルカリ性懸濁液とし、この懸濁液を非酸化性雰
囲気下、沸点以下の温度で加熱攪拌することにより前記
針状磁性酸化鉄粒子の表面をCo化合物によって変成さ
せ、次いで、当該懸濁液を60℃以下の温度とした後、
Fe2+塩水溶液を添加・混合し、非酸化性雰囲気下、
沸点以下の温度で加熱攪拌することにより前記針状磁性
酸化鉄粒子の表面を更にFe化合物によって変成させ、
次いで、当該懸濁液を60℃以下の温度とした後、Co
塩水溶液とSi化合物とを添加・混合し、非酸化性雰囲
気下、沸点以下の温度で加熱攪拌することにより前記針
状磁性酸化鉄粒子の表面の最上層をSiを含むCo化合
物によって変成させた後、濾別、水洗、乾燥して針状磁
性酸化鉄粒子粉末を得ることを特徴とする磁気記録用針
状磁性酸化鉄粒子粉末の製造法。
Claim 1: Add and mix a Co salt aqueous solution to an aqueous dispersion of acicular magnetic iron oxide particle powder in a non-oxidizing atmosphere at a temperature of 60° C. or lower, and add an alkali hydroxide aqueous solution to this mixture to make it alkaline. The surface of the acicular magnetic iron oxide particles is modified with a Co compound by heating and stirring this suspension at a temperature below the boiling point in a non-oxidizing atmosphere, and then the suspension is heated to 60°C. After bringing the temperature below ℃,
Add and mix Fe2+ salt aqueous solution, under non-oxidizing atmosphere,
Further modifying the surface of the acicular magnetic iron oxide particles with an Fe compound by heating and stirring at a temperature below the boiling point,
Next, after bringing the temperature of the suspension to 60°C or less, Co
An aqueous salt solution and a Si compound were added and mixed, and the top layer on the surface of the acicular magnetic iron oxide particles was modified by a Co compound containing Si by heating and stirring in a non-oxidizing atmosphere at a temperature below the boiling point. A method for producing acicular magnetic iron oxide particles for magnetic recording, the method comprising the following steps: filtering, washing with water, and drying to obtain acicular magnetic iron oxide particles.
【請求項2】  針状磁性酸化鉄粒子粉末の水性分散液
に非酸化性雰囲気下、60℃以下の温度でCo塩水溶液
とFe2+塩水溶液又はCo塩水溶液とSi化合物もし
くはCo塩水溶液、Fe2+塩水溶液及びSi化合物と
を添加・混合し、この混合液に水酸化アルカリ水溶液を
加えてアルカリ性懸濁液とし、この懸濁液を非酸化性雰
囲気下、沸点以下の温度で加熱攪拌することにより前記
針状磁性酸化鉄粒子の表面をCo化合物とFe化合物又
はSiを含むCo化合物もしくはSiを含むCo化合物
とFe化合物とによって変成させ、次いで、当該懸濁液
を60℃以下の温度とした後、Fe2+塩水溶液を添加
・混合し、非酸化性雰囲気下、沸点以下の温度で加熱攪
拌することにより前記針状磁性酸化鉄粒子の表面を更に
Fe化合物によって変成させ、次いで、当該懸濁液を6
0℃以下の温度とした後、Co塩水溶液とSi化合物と
を添加・混合し、非酸化性雰囲気下、沸点以下の温度で
加熱攪拌することにより前記針状磁性酸化鉄粒子の表面
の最上層をSiを含むCo化合物によって変成させた後
、濾別、水洗、乾燥して針状磁性酸化鉄粒子粉末を得る
ことを特徴とする磁気記録用針状磁性酸化鉄粒子粉末の
製造法。
[Claim 2] Co salt aqueous solution and Fe2+ salt aqueous solution, or Co salt aqueous solution and Si compound or Co salt aqueous solution, Fe2+ salt are added to an aqueous dispersion of acicular magnetic iron oxide particle powder in a non-oxidizing atmosphere at a temperature of 60° C. or less. An aqueous solution and a Si compound are added and mixed, an alkali hydroxide aqueous solution is added to this mixed solution to obtain an alkaline suspension, and this suspension is heated and stirred at a temperature below the boiling point in a non-oxidizing atmosphere. After denaturing the surface of the acicular magnetic iron oxide particles with a Co compound and a Fe compound, or a Co compound containing Si, or a Co compound containing Si and a Fe compound, and then bringing the temperature of the suspension to 60° C. or lower, The surface of the acicular magnetic iron oxide particles is further modified with the Fe compound by adding and mixing an aqueous Fe2+ salt solution and heating and stirring at a temperature below the boiling point in a non-oxidizing atmosphere, and then the suspension is
After bringing the temperature to 0° C. or lower, a Co salt aqueous solution and a Si compound are added and mixed, and heated and stirred in a non-oxidizing atmosphere at a temperature lower than the boiling point to form the top layer on the surface of the acicular magnetic iron oxide particles. A method for producing acicular magnetic iron oxide particles for magnetic recording, which comprises modifying the powder with a Co compound containing Si, followed by filtering, washing with water, and drying to obtain acicular magnetic iron oxide particles.
【請求項3】  針状磁性酸化鉄粒子粉末の水性分散液
に非酸化性雰囲気下、60℃以下の温度でCo塩水溶液
を添加・混合し、この混合液に水酸化アルカリ水溶液を
加えてアルカリ性懸濁液とし、この懸濁液を非酸化性雰
囲気下、沸点以下の温度で加熱攪拌することにより前記
針状磁性酸化鉄粒子の表面をCo化合物によって変成さ
せ、次いで、当該懸濁液を60℃以下の温度とした後、
Fe2+塩水溶液とCo塩水溶液又はFe2+塩水溶液
とSi化合物もしくはFe2+塩水溶液、Co塩水溶液
及びSi化合物とを添加・混合し、非酸化性雰囲気下、
沸点以下の温度で加熱攪拌することにより前記針状磁性
酸化鉄粒子の表面を更にFe化合物とCo化合物又はS
iを含むFe化合物もしくはSiを含むFe化合物とC
o化合物とによって変成させ、次いで、当該懸濁液を6
0℃以下の温度とした後、Co塩水溶液とSi化合物と
を添加・混合し、非酸化性雰囲気下、沸点以下の温度で
加熱攪拌することにより前記針状磁性酸化鉄粒子の表面
の最上層をSiを含むCo化合物によって変成させた後
、濾別、水洗、乾燥して針状磁性酸化鉄粒子粉末を得る
ことを特徴とする磁気記録用針状磁性酸化鉄粒子粉末の
製造法。
3. Add and mix a Co salt aqueous solution to an aqueous dispersion of acicular magnetic iron oxide particle powder in a non-oxidizing atmosphere at a temperature of 60° C. or less, and add an alkali hydroxide aqueous solution to this mixture to make it alkaline. The surface of the acicular magnetic iron oxide particles is modified with a Co compound by heating and stirring this suspension at a temperature below the boiling point in a non-oxidizing atmosphere, and then the suspension is heated to 60°C. After bringing the temperature below ℃,
Add and mix Fe2+ salt aqueous solution and Co salt aqueous solution or Fe2+ salt aqueous solution and Si compound or Fe2+ salt aqueous solution, Co salt aqueous solution and Si compound, under a non-oxidizing atmosphere,
By heating and stirring at a temperature below the boiling point, the surface of the acicular magnetic iron oxide particles is further coated with Fe compound and Co compound or S.
Fe compound containing i or Fe compound containing Si and C
o compound, and then the suspension was denatured with 6
After bringing the temperature to 0° C. or lower, a Co salt aqueous solution and a Si compound are added and mixed, and heated and stirred in a non-oxidizing atmosphere at a temperature lower than the boiling point to form the top layer on the surface of the acicular magnetic iron oxide particles. A method for producing acicular magnetic iron oxide particles for magnetic recording, which comprises modifying the powder with a Co compound containing Si, followed by filtering, washing with water, and drying to obtain acicular magnetic iron oxide particles.
【請求項4】  針状磁性酸化鉄粒子粉末の水性分散液
に非酸化性雰囲気下、60℃以下の温度でCo塩水溶液
とFe2+塩水溶液又はCo塩水溶液とSi化合物もし
くはCo塩水溶液、Fe2+塩水溶液及びSi化合物と
を添加・混合し、この混合液に水酸化アルカリ水溶液を
加えてアルカリ性懸濁液とし、この懸濁液を非酸化性雰
囲気下、沸点以下の温度で加熱攪拌することにより前記
針状磁性酸化鉄粒子の表面をCo化合物とFe化合物又
はSiを含むCo化合物もしくはSiを含むCo化合物
とFe化合物とによって変成させ、次いで、当該懸濁液
を60℃以下の温度とした後、Fe2+塩水溶液とCo
塩水溶液又はFe2+塩水溶液とSi化合物もしくはF
e2+塩水溶液、Co塩水溶液及びSi化合物とを添加
・混合し、非酸化性雰囲気下、沸点以下の温度で加熱攪
拌することにより前記針状磁性酸化鉄粒子の表面を更に
Fe化合物とCo化合物又はSiを含むFe化合物もし
くはSiを含むFe化合物とCo化合物とによって変成
させ、次いで、当該懸濁液を60℃以下の温度とした後
、Co塩水溶液とSi化合物とを添加・混合し、非酸化
性雰囲気下、沸点以下の温度で加熱攪拌することにより
前記針状磁性酸化鉄粒子の表面の最上層をSiを含むC
o化合物によって変成させた後、濾別、水洗、乾燥して
針状磁性酸化鉄粒子粉末を得ることを特徴とする磁気記
録用針状磁性酸化鉄粒子粉末の製造法。
4. Co salt aqueous solution and Fe2+ salt aqueous solution, or Co salt aqueous solution and Si compound or Co salt aqueous solution, Fe2+ salt in an aqueous dispersion of acicular magnetic iron oxide particle powder at a temperature of 60° C. or less in a non-oxidizing atmosphere. An aqueous solution and a Si compound are added and mixed, an alkali hydroxide aqueous solution is added to this mixed solution to obtain an alkaline suspension, and this suspension is heated and stirred at a temperature below the boiling point in a non-oxidizing atmosphere. After denaturing the surface of the acicular magnetic iron oxide particles with a Co compound and a Fe compound, or a Co compound containing Si, or a Co compound containing Si and a Fe compound, and then bringing the temperature of the suspension to 60° C. or lower, Fe2+ salt aqueous solution and Co
Salt aqueous solution or Fe2+ salt aqueous solution and Si compound or F
By adding and mixing e2+ salt aqueous solution, Co salt aqueous solution and Si compound, and heating and stirring at a temperature below the boiling point in a non-oxidizing atmosphere, the surface of the acicular magnetic iron oxide particles is further coated with Fe compound and Co compound or The suspension is denatured with a Fe compound containing Si or a Fe compound containing Si and a Co compound, and then the temperature of the suspension is lowered to 60°C, and then an aqueous Co salt solution and a Si compound are added and mixed to form a non-oxidized By heating and stirring in a magnetic atmosphere at a temperature below the boiling point, the top layer on the surface of the acicular magnetic iron oxide particles is converted to carbon containing Si.
A method for producing acicular magnetic iron oxide particles for magnetic recording, which comprises modifying the powder with an o compound, followed by filtering, washing with water, and drying to obtain acicular magnetic iron oxide particles.
JP3089500A 1991-03-27 1991-03-27 Method for producing acicular magnetic iron oxide particles for magnetic recording Expired - Fee Related JP2885252B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3089500A JP2885252B2 (en) 1991-03-27 1991-03-27 Method for producing acicular magnetic iron oxide particles for magnetic recording

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3089500A JP2885252B2 (en) 1991-03-27 1991-03-27 Method for producing acicular magnetic iron oxide particles for magnetic recording

Publications (2)

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JPH04299505A true JPH04299505A (en) 1992-10-22
JP2885252B2 JP2885252B2 (en) 1999-04-19

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