JPH07223822A - Acicular alpha-ferric oxide and production thereof - Google Patents
Acicular alpha-ferric oxide and production thereofInfo
- Publication number
- JPH07223822A JPH07223822A JP6017586A JP1758694A JPH07223822A JP H07223822 A JPH07223822 A JP H07223822A JP 6017586 A JP6017586 A JP 6017586A JP 1758694 A JP1758694 A JP 1758694A JP H07223822 A JPH07223822 A JP H07223822A
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- Prior art keywords
- ferric
- acicular
- suspension
- ferric oxide
- ratio
- Prior art date
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- Compounds Of Iron (AREA)
- Hard Magnetic Materials (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、空孔を有せず、針状
比、粒度分布及び独立性（粒子が凝縮していない状態）
にすぐれた針状α−酸化第二鉄及びその製造法に関し、
このような針状α−酸化第二鉄は、磁気記録用磁性酸化
鉄の原料として好適に用いられるものである。また、特
異な結晶成長方向を示すことから、透明性赤色顔料やフ
ェライト用原料としても有用である。INDUSTRIAL APPLICABILITY The present invention does not have pores and has an acicular ratio, a particle size distribution and independence (state in which particles are not condensed).
Excellent acicular α-ferric oxide and a method for producing the same,
Such acicular α-ferric oxide is preferably used as a raw material for magnetic iron oxide for magnetic recording. Further, since it shows a peculiar crystal growth direction, it is also useful as a transparent red pigment or a raw material for ferrite.
【０００２】[0002]
【従来の技術】磁気記録用磁性酸化鉄に対する基本的な
要求特性としては、以下に示す４点が挙げられる。第１
に、空孔を有せず、実質的に高密度であることである。
粒子中に空孔が存在すると、その空孔周辺に磁極の発生
を招来し、自発磁化が部分的に乱れて、磁気特性に悪影
響を及ぼす。第２に、粒子の長軸径（ｌ）と短軸径
（ｄ）の比、即ち、針状比（ｌ／ｄ）が大きいことであ
る。針状比が大きくなると、磁性粒子内部に生じる反磁
界が小さくなり、保磁力が大きい値となる。第３に、粒
度分布が狭いことである。粒度分布が広いと、磁気テー
プの重要な特性の一つである反転磁界分布（ｎ−ＳＦ
Ｄ）に悪影響を及ぼす。第４に、磁気記録媒体に高密度
記録が要求される場合は、粒子の微細化が必要となる。2. Description of the Related Art The following four basic characteristics are required for magnetic iron oxide for magnetic recording. First
In addition, it has no pores and has a substantially high density.
The presence of holes in the particles causes the generation of magnetic poles around the holes, the spontaneous magnetization is partially disturbed, and the magnetic properties are adversely affected. Secondly, the ratio of the major axis diameter (1) to the minor axis diameter (d) of the particles, that is, the acicular ratio (1 / d) is large. When the acicular ratio becomes large, the demagnetizing field generated inside the magnetic particles becomes small and the coercive force becomes large. Thirdly, the particle size distribution is narrow. When the particle size distribution is wide, the switching field distribution (n-SF), which is one of the important characteristics of the magnetic tape,
Adversely affect D). Fourthly, when high density recording is required for the magnetic recording medium, it is necessary to make the particles finer.
【０００３】以上のように、空孔を有せず、針状比が大
きく、粒度分布にすぐれ、且つ、微細であることは、磁
気記録用磁性酸化鉄においては、最も重要で、且つ、基
本的な要求特性であり、原料となる針状α−酸化第二鉄
においても、必要不可欠な要件となる。As described above, it is the most important and basic in magnetic iron oxide for magnetic recording that it has no pores, has a large acicular ratio, has an excellent particle size distribution, and is fine. Is a required characteristic, and it is an indispensable requirement also in the acicular α-ferric oxide as a raw material.
【０００４】一般に、針状α−酸化第二鉄は、含水酸化
第二鉄（α−ＦｅＯＯＨ）を加熱脱水し、その針状性を
維持しつつ、結晶変態を生じさせる所謂トポタクテイッ
ク反応によつて製造されることが多い。この製造方法に
よれば、含水酸化第二鉄１モル当たり0.５モルの水分子
が結晶から失われ、その際に生じる脱水孔がそのまま
か、若しくは集合した状態で空孔として結晶内部に残
り、その割合は約３０容積％であるといわれている。こ
のような多孔性の針状α−酸化第二鉄を磁気記録用磁性
酸化鉄の原料として用いた場合は、得られる針状γ−酸
化第二鉄中にも同様に空孔が残存し、低出力の磁気記録
媒体しか得られないという欠点がある。Generally, acicular α-ferric oxide is formed by a so-called topotatactic reaction in which hydrous ferric oxide (α-FeOOH) is dehydrated by heating to maintain crystallinity while maintaining its acicularity. Often manufactured. According to this production method, 0.5 mol of water molecules are lost from the crystal per 1 mol of ferric hydroxide, and the dehydration pores generated at that time remain in the crystal as voids in the state as they are or in an aggregated state. It is said that the ratio is about 30% by volume. When such a porous acicular α-ferric oxide is used as a raw material for magnetic iron oxide for magnetic recording, voids similarly remain in the acicular γ-ferric oxide obtained, There is a drawback that only a low output magnetic recording medium can be obtained.
【０００５】そこで、このような空孔を少なくすべく、
従来、種々の方法が提案されているが、理論的に脱水孔
がなくなることはなく、仮に、高温焼成することによつ
て、空孔が少なくなったとしても、粒子が焼結して融着
し、分散性が低下する等の２次的な欠点を生じる。Therefore, in order to reduce such holes,
Conventionally, various methods have been proposed, but theoretically the dehydration holes do not disappear, and even if the number of pores is reduced by firing at high temperature, the particles will sinter and fuse together. However, secondary defects such as reduced dispersibility occur.
【０００６】他方、上述したような問題を根本的に解決
するために、α−ＦｅＯＯＨを経ることなく、湿式で直
接に針状α−酸化第二鉄を製造する方法も開発されてい
る。その方法によれば、独立性にすぐれ、且つ、空孔を
有しない針状α−酸化第二鉄を得ることができ、この針
状α−酸化第二鉄を原料として得られる針状γ−酸化第
二鉄もまた、空孔を有せず、実質的に高密度であり、磁
気特性にすぐれたものになる。On the other hand, in order to fundamentally solve the above-mentioned problems, a method of directly producing acicular α-ferric oxide by a wet method without using α-FeOOH has been developed. According to this method, acicular α-ferric oxide having excellent independence and having no pores can be obtained, and acicular γ-obtained by using this acicular α-ferric oxide as a raw material. Ferric oxide also has no pores, is substantially dense, and has excellent magnetic properties.
【０００７】例えば、特公昭５５−２２４１６号公報に
は、水酸化第二鉄、クエン酸及び／又はその塩、アルカ
リ化合物の３成分が共存する水性スラリーをアルカリ性
領域で１００〜２５０℃で加熱処理する方法が開示され
ており、その方法によれば、長軸径0.５μ、針状比７の
粒子が得られるとされている。特公昭５５−４６９４号
公報には、少なくとも一種の有機ホスホン酸化合物の存
在下、水酸化第二鉄の沈殿の水性懸濁液をアルカリ性ｐ
Ｈ領域において、加熱処理する方法が開示されており、
その方法によれば、長軸５μ、短軸0.３μの粒子が得ら
れるとされている。この粒子は、針状比約１７を有する
が、粒子径が大きく、その比表面積は１０ｍ2 ／ｇにも
達しない。For example, in Japanese Patent Publication No. 55-22416, an aqueous slurry in which three components of ferric hydroxide, citric acid and / or its salt, and an alkali compound coexist is heat treated at 100 to 250 ° C. in an alkaline region. Is disclosed, and it is said that particles having a major axis diameter of 0.5 μ and an acicular ratio of 7 can be obtained. Japanese Patent Publication No. 55-4694 discloses an aqueous suspension of ferric hydroxide precipitate in the presence of at least one organic phosphonic acid compound.
A method for heat treatment in the H region is disclosed,
According to the method, particles having a long axis of 5μ and a short axis of 0.3μ are obtained. The particles have an acicular ratio of about 17, but have a large particle size and their specific surface area does not reach 10 m 2 / g.
【０００８】本発明者らの研究によれば、上記２つの従
来の技術文献に開示された方法を用いれば、４０ｍ2 ／
ｇまでの比表面積を有する粒子を得ることは可能である
が、そのような粒子は、針状比及び粒度分布が悪く、磁
気記録用磁性酸化鉄の原料としては好ましくない。According to the research conducted by the present inventors, it is possible to obtain 40 m 2 /
Although it is possible to obtain particles having a specific surface area of up to g, such particles are not preferable as a raw material of magnetic iron oxide for magnetic recording due to poor acicular ratio and particle size distribution.
【０００９】特開昭６２−２１６９１９号公報には、少
なくとも鉄（III)イオンと錯塩を形成する有機化合物の
存在下に、水酸化鉄（III)のアルカリ性水性懸濁液を８
０〜２５０℃の温度に加熱することによつて、針状α−
Ｆｅ2 Ｏ3 を製造する方法において、スズ（IV）イオン
で変性した水酸化鉄（III)を用いる方法が開示されてい
る。その方法によれば、長軸径0.３μ、針状比１0.０、
比表面積３3.０ｍ2 ／ｇの粒子が得られるとされてい
る。特開平１−２７０５２０号公報には、特開昭６２−
２１６９１９号公報とほぼ同様の内容であるが、水洗を
行なわない利点を有する方法が開示されている。この技
術文献には、得られる粒子の長軸径及び針状比について
の記載はないが、比表面積３6.９ｍ2 ／ｇの粒子が得ら
れるとされている。JP-A-62-216919 discloses an alkaline aqueous suspension of iron (III) hydroxide in the presence of at least an organic compound forming a complex salt with iron (III) ions.
By heating to a temperature of 0 to 250 ° C, needle-like α-
A method for producing Fe 2 O 3 using iron (III) hydroxide modified with tin (IV) ions is disclosed. According to the method, the major axis diameter is 0.3 μ, the needle ratio is 10.0,
It is said that particles having a specific surface area of 33.0 m 2 / g can be obtained. Japanese Unexamined Patent Publication No. 1-275020 discloses Japanese Unexamined Patent Publication No. 62-
Although the content is almost the same as that of the 216919 gazette, a method having an advantage of not performing water washing is disclosed. Although this technical document does not describe the major axis diameter and the acicular ratio of the obtained particles, it is said that particles having a specific surface area of 36.9 m 2 / g can be obtained.
【００１０】また、特開昭６３−５０３２６号公報に
は、水酸化第二鉄の水性懸濁液を４価の金属化合物単独
か、又は４価の金属化合物とリン化合物及び／又はオキ
シカルボン酸化合物との存在下で、アルカリ性ｐＨ領域
において加熱処理する方法が開示されており、この方法
によれば，長軸径0.４μ、針状比７、比表面積２4.５ｍ
2 ／ｇの粒子が得られるとされている。更に、特開昭６
３−１６２５３５号公報には、β−ＦｅＯＯＨを含むｐ
Ｈ７以下の水性懸濁液にリン化合物を添加した後、１０
０〜１３０℃の範囲の温度で水熱処理する方法が開示さ
れている。この方法によれば、長軸径0.８μの粒子が得
られるとされており、その技術文献に記載されている粒
子の写真から判断すれば、針状比は６〜８程度である。Further, in Japanese Patent Laid-Open No. 63-50326.
Is an aqueous suspension of ferric hydroxide containing a tetravalent metal compound alone.
Or tetravalent metal compound and phosphorus compound and / or oki
Alkaline pH range in the presence of sicarboxylic acid compounds
In this method, heat treatment is disclosed.
According to the major axis diameter 0.4μ, needle ratio 7, specific surface area 24.5m
2/ G of particles are said to be obtained. Furthermore, JP-A-6
JP-A-3-162535 discloses p containing β-FeOOH.
After adding the phosphorus compound to the H7 or less aqueous suspension, 10
A method for hydrothermal treatment at a temperature in the range of 0 to 130 ° C is disclosed.
Has been. This method yields particles with a major axis of 0.8μ.
And are described in the technical literature.
Judging from the photograph of the child, the acicular ratio is about 6-8.
【００１１】以上のように、従来、種々の方法が提案さ
れているものの、湿式法によつて直接に針状のα−酸化
第二鉄を得る方法において、針状比が１０以上で、且
つ、比表面積が２０〜４０ｍ2 ／ｇであり、しかも、実
質的に空孔を有しない針状α−酸化第二鉄は、未だ知ら
れていない。As described above, although various methods have been conventionally proposed, in the method of directly obtaining acicular α-ferric oxide by a wet method, the acicular ratio is 10 or more, and Needle-like α-ferric oxide having a specific surface area of 20 to 40 m 2 / g and substantially no pores has not yet been known.
【００１２】[0012]
【発明が解決しようとする課題】そこで、本発明は、湿
式法によつて直接に針状のα−酸化第二鉄を得る方法に
おいて、粒度分布及び針状比の改善を実現して、実質的
に空孔を有しない微細な針状α−酸化第二鉄と、そのよ
うな針状α−酸化第二鉄を製造する方法を提供すること
を目的とする。Therefore, the present invention provides a method for directly obtaining acicular α-ferric oxide by a wet method, which realizes improvement of particle size distribution and acicular ratio, It is an object of the present invention to provide fine acicular α-ferric oxide having no vacant holes and a method for producing such acicular α-ferric oxide.
【００１３】[0013]
【課題を解決するための手段】本発明による針状α−酸
化第二鉄は、（１０４）面に垂直方向の結晶子径Ｄ10 4
と（１１０）面に垂直方向の結晶子径Ｄ110 の比Ｄ104
／Ｄ110 が１〜２であり、平均針状比が１０〜１５であ
り、更に、比表面積が２０〜４０m2／ｇであることを特
徴とする。The acicular α-ferric oxide according to the present invention has a crystallite diameter D 10 4 in the direction perpendicular to the (104) plane.
And the ratio D 104 of the crystallite diameter D 110 in the direction perpendicular to the (110) plane
/ D 110 is 1-2, the average acicular ratio is 10-15, and the specific surface area is 20-40 m 2 / g.
【００１４】本明細書において、（１０４）面は、In this specification, the (104) plane is
【００１５】[0015]
【数１】 [Equation 1]
【００１６】と同義であり、（１１０）面は、Is the same as, and the (110) plane is
【００１７】[0017]
【数２】 [Equation 2]
【００１８】と同義であり、結晶子径Ｄ104 は、And has a crystallite diameter D 104 of
【００１９】[0019]
【数３】 [Equation 3]
【００２０】と同義であり、結晶子径Ｄ110 は、And has a crystallite diameter D 110 of
【００２１】[0021]
【数４】 [Equation 4]
【００２２】と同義である。Is synonymous with
【００２３】本発明による針状α−酸化第二鉄の製造方
法は、第二鉄塩水溶液にアルカリ水溶液を、中和液の温
度を３０℃以下に保ちながら、ｐＨが７〜１０になるま
で添加して、水酸化第二鉄の懸濁液を得、これを濾過、
水洗後、再懸濁して、得られた再懸濁液中のＳｉＯ2 量
を６０ｐｐｍ以下とし、且つ、原料第二鉄塩に由来する
アニオン量を２０００ｐｐｍ以下とした後、この水酸化
第二鉄の懸濁液を４０〜１００℃にて熟成し、次いで、
この懸濁液に結晶化制御剤を加えて、水熱反応を行なう
ことを特徴とする。The method for producing needle-like α-ferric oxide according to the present invention is carried out by adding an alkaline aqueous solution to an aqueous ferric salt solution and keeping the temperature of the neutralizing solution at 30 ° C. or lower until the pH becomes 7 to 10. Addition to give a suspension of ferric hydroxide, which is filtered,
After washing with water and resuspension, the amount of SiO 2 in the obtained resuspension was adjusted to 60 ppm or less, and the amount of anions derived from the ferric iron salt raw material was adjusted to 2000 ppm or less, and then the ferric hydroxide was added. Aging the suspension at 40-100 ° C, then
A crystallization control agent is added to this suspension to carry out a hydrothermal reaction.
【００２４】以下に、本発明による針状α−酸化第二鉄
の製造方法について詳細に説明する。本発明の方法によ
れば、先ず、第二鉄塩水溶液にアルカリ水溶液を添加し
て、無定形水酸化第二鉄の懸濁液を得る。この際、中和
温度は３０℃以下であり、しかも、中和後の懸濁液のｐ
Ｈが７〜１０の範囲にあることが必要である。中和温度
が３０℃を越えるときは、得られる針状α−酸化第二鉄
の粒度分布に悪影響を与え、また、懸濁液のｐＨが上記
範囲をはずれるときは、得られる針状α−酸化第二鉄の
針状比及び粒度分布に悪影響を与える。The method for producing acicular α-ferric oxide according to the present invention will be described in detail below. According to the method of the present invention, first, an aqueous alkaline solution is added to an aqueous ferric salt solution to obtain a suspension of amorphous ferric hydroxide. At this time, the neutralization temperature is 30 ° C. or lower, and the p
It is necessary that H is in the range of 7 to 10. When the neutralization temperature exceeds 30 ° C, the particle size distribution of the acicular α-ferric oxide obtained is adversely affected, and when the pH of the suspension is out of the above range, the acicular α-obtained is obtained. It adversely affects the acicular ratio and particle size distribution of ferric oxide.
【００２５】本発明において用いる上記第二鉄塩として
は、塩化第二鉄、硫酸第二鉄、硝酸第二鉄等を挙げるこ
とができ、アルカリとしては、水酸化ナトリウム、水酸
化カリウム、アンモニア等を挙げることができる。得ら
れる水酸化第二鉄懸濁液の濃度は、攪拌が困難でない程
度でよく、通常1.０モル／リットル以下であり、好まし
くは、0.０５〜0.３モル／リットルの範囲である。Examples of the ferric salt used in the present invention include ferric chloride, ferric sulfate and ferric nitrate, and examples of the alkali include sodium hydroxide, potassium hydroxide and ammonia. Can be mentioned. The concentration of the ferric hydroxide suspension obtained may be such that stirring is not difficult and is usually 1.0 mol / liter or less, preferably in the range of 0.05 to 0.3 mol / liter. .
【００２６】次いで、本発明の方法によれば、中和反応
によつて副生した塩類を除去するために、水酸化第二鉄
の懸濁液の濾過及びリパルプ水洗を行なう。この際、水
洗後の水酸化第二鉄懸濁液中に含まれるＳｉＯ2 量が６
０ｐｐｍ以下、好ましくは、４０ｐｐｍ以下であり、且
つ、原料第二鉄塩に由来するアニオン量が２０００ｐｐ
ｍ以下、好ましくは、１５００ｐｐｍ以下となるよう
に、水洗水中のＳｉＯ2濃度を調整し、更に、水洗水量
をも適宜に調整することが必要である。Next, according to the method of the present invention, in order to remove salts by-produced by the neutralization reaction, the suspension of ferric hydroxide is filtered and washed with repulp. At this time, the amount of SiO 2 contained in the ferric hydroxide suspension after washing with water was 6
0 ppm or less, preferably 40 ppm or less, and the amount of anions derived from the ferric salt of the raw material is 2000 pp
It is necessary to adjust the SiO 2 concentration in the wash water so as to be m or less, preferably 1500 ppm or less, and also appropriately adjust the wash water amount.
【００２７】本発明による針状比及び粒度分布にすぐれ
る針状α−酸化第二鉄を得るためには、熟成前の水酸化
第二鉄懸濁液中のＳｉＯ2 量及び原料第二鉄塩に由来す
るアニオン量について、両者共に上記条件を満たすこと
が必要である。いずれか一方の条件を満たしたのみで
は、目的とする針状α−酸化第二鉄を得ることができな
い。残存アニオン量が多いときは、主として、針状比が
低下し、ＳｉＯ2 量が多いときは、主として粒度分布に
悪影響を及ぼす。In order to obtain acicular α-ferric oxide having an excellent acicular ratio and particle size distribution according to the present invention, the amount of SiO 2 in the ferric hydroxide suspension before aging and the ferric iron raw material are used. Both of the amounts of anions derived from the salt must satisfy the above conditions. The target acicular α-ferric oxide cannot be obtained only by satisfying one of the conditions. When the amount of residual anions is large, the acicular ratio mainly decreases, and when the amount of SiO 2 is large, it mainly affects the particle size distribution.
【００２８】本発明の方法によれば、このような水洗の
後に、均一な核を生成させることを目的として、水酸化
第二鉄懸濁液を熟成する。この際、水酸化第二鉄の濃度
は0.１〜1.0 モル／リットルの範囲が好ましい。熟成
は、水酸化第二鉄懸濁液のｐＨを７〜８に調整した後、
４０℃〜１００℃の温度で２〜４時間程度行なうのが好
ましい。この熟成の温度が４０℃よりも低いときは、熟
成効果を十分に得ることができない。また、熟成の時間
が２時間よりも短いときも、熟成の効果に乏しい。しか
し、４時間を上回るときは、粒度分布が悪くなる。According to the method of the present invention, after such washing with water, the suspension of ferric hydroxide is aged for the purpose of producing uniform nuclei. At this time, the concentration of ferric hydroxide is preferably in the range of 0.1 to 1.0 mol / liter. For aging, after adjusting the pH of the ferric hydroxide suspension to 7 to 8,
It is preferable to carry out at a temperature of 40 ° C. to 100 ° C. for about 2 to 4 hours. When the aging temperature is lower than 40 ° C, the aging effect cannot be sufficiently obtained. Also, when the aging time is shorter than 2 hours, the effect of aging is poor. However, when it exceeds 4 hours, the particle size distribution becomes worse.
【００２９】本発明の方法によれば、次いで、かかる熟
成後の水酸化第二鉄懸濁液に結晶化制御剤を添加する。
結晶化制御剤は、鉄に対する配位能を有し、生成するα
−酸化第二鉄の結晶成長方向と速度を制御して、針状粒
子を得るために用いる。かかる結晶化制御剤は、既に知
られている。具体的には、特公昭６０−２９６４６号公
報に記載されているように、ポリカルボン酸、ヒドロキ
シカルボン酸、アミノカルボン酸、ポリアミン、有機ホ
スホン酸、チオカルボン酸、多価アルコール、β−ジカ
ルボニル化合物、芳香族スルホン酸等が用いられ、これ
らの水溶液の塩やエステルも、鉄に対して配位能を有す
る限りは、結晶化制御剤として用いることができる。According to the method of the present invention, a crystallization controlling agent is then added to the ferric hydroxide suspension after the aging.
The crystallization control agent has a coordination ability with respect to iron and produces α
Used to obtain needle-shaped particles by controlling the crystal growth direction and speed of ferric oxide. Such crystallization control agents are already known. Specifically, as described in JP-B-60-29646, polycarboxylic acid, hydroxycarboxylic acid, aminocarboxylic acid, polyamine, organic phosphonic acid, thiocarboxylic acid, polyhydric alcohol, β-dicarbonyl compound. , Aromatic sulfonic acid and the like are used, and salts and esters of these aqueous solutions can also be used as a crystallization control agent as long as they have a coordination ability with iron.
【００３０】本発明においては、これらのうち、特に好
ましいものとして、例えば、クエン酸、酒石酸、アミノ
トリ（メチレンホスホン酸）、エチレンジアミノテトラ
（メチレンホスホン酸）、エチレン−1,1'−ジホスホン
酸等を挙げることができる。In the present invention, among these, particularly preferable are, for example, citric acid, tartaric acid, aminotri (methylenephosphonic acid), ethylenediaminotetra (methylenephosphonic acid), ethylene-1,1'-diphosphonic acid and the like. Can be mentioned.
【００３１】本発明において、結晶化制御剤の使用量
は、水熟反応において、α−酸化第二鉄の結晶成長方向
と速度を制御するのに足る量であれば、特に制限されな
いが、通常、水酸化第二鉄１モルに対して、１×１０-5
〜１×１０-1モル、好ましくは、１×１０-4〜１×１０
-2モルの範囲である。結晶化制御剤の使用量が少なすぎ
るときは、針状比にすぐれるα−酸化第二鉄を得ること
が困難であり、他方、過多に用いるときは、反応に長時
間を要するので好ましくない。In the present invention, the amount of the crystallization control agent used is not particularly limited as long as it is an amount sufficient to control the crystal growth direction and rate of α-ferric oxide in the water maturation reaction, but is usually , 1 × 10 -5 per 1 mol of ferric hydroxide
˜1 × 10 −1 mol, preferably 1 × 10 −4 to 1 × 10
-In the range of 2 moles. When the amount of the crystallization control agent used is too small, it is difficult to obtain α-ferric oxide having an excellent acicular ratio. On the other hand, when it is used in excess, the reaction takes a long time, which is not preferable. .
【００３２】本発明の方法によれば、最終の工程とし
て、上述したように処理した水酸化第二鉄の懸濁液に水
熟反応を行なう。この水熟反応は、懸濁液にアルカリを
加えて、そのｐＨを９〜１１の範囲とし、これを１００
℃以上の温度に加熱することによって行なう。ここに、
用いるアルカリとしては、水酸化ナトリウム、水酸化カ
リウム、アンモニア等を挙げることができる。According to the method of the present invention, as a final step, the suspension of ferric hydroxide treated as described above is subjected to a water maturation reaction. In this water-ripening reaction, alkali is added to the suspension to adjust its pH to the range of 9 to 11, and the pH is adjusted to 100.
It is performed by heating to a temperature of ℃ or more. here,
Examples of the alkali used include sodium hydroxide, potassium hydroxide and ammonia.
【００３３】水熱反応における反応温度は、上述したよ
うに、１００℃以上であつて、その上限温度は、用いる
結晶化制御剤の熱分解しない温度であり、反応時間は、
通常、数十分から数時間である。反応温度が１００℃よ
りも低いときは、十字形やＴ字形の粒子や、或いはα−
ＦｅＯＯＨの生成が認められ、独立性にすぐれた針状α
−酸化第二鉄を得ることが困難である。反応温度は、通
常、１００〜２５０℃の範囲であり、好ましくは、１３
０〜２００℃の範囲である。反応終了後、冷却し、常法
にて、濾過、水洗、乾燥することによつて、本発明によ
る針状α−酸化第二鉄を得ることができる。As described above, the reaction temperature in the hydrothermal reaction is 100 ° C. or higher, the upper limit temperature is a temperature at which the crystallization controlling agent used is not thermally decomposed, and the reaction time is
It is usually several tens of minutes to several hours. When the reaction temperature is lower than 100 ° C, cross-shaped particles, T-shaped particles, or α-
Formation of FeOOH was observed, and needle-shaped α with excellent independence
-It is difficult to obtain ferric oxide. The reaction temperature is usually in the range of 100 to 250 ° C., preferably 13
It is in the range of 0 to 200 ° C. After completion of the reaction, the reaction mixture is cooled, filtered, washed with water, and dried by a conventional method to obtain the acicular α-ferric oxide of the present invention.
【００３４】このようにして得られる本発明による針状
α−酸化第二鉄は、その内部に有する結晶子において、
α−ＦｅＯＯＨを加熱脱水して得られる針状α−酸化第
二鉄とは、異なつた様態を有する。前者と後者につい
て、それぞれ（１０４）面に垂直方向の結晶子径Ｄ104
と（１１０）面に垂直方向の結晶子径Ｄ110 の比（Ｄ10
4 ／Ｄ110 ）をとると、前者はＤ104 ／Ｄ110 ＝１〜２
であるのに対し、後者はＤ104 ／Ｄ110 ＝0.５〜0.９で
ある。このことは、本発明による針状α−酸化第二鉄の
結晶子は、Ｃ軸方向によく成長していることを示してお
り、粒子の長軸方向は〔００１〕方向と考えられる。The needle-shaped α-ferric oxide according to the present invention thus obtained has a crystallite inside thereof,
It has a different form from the acicular α-ferric oxide obtained by heating and dehydrating α-FeOOH. For the former and the latter, the crystallite diameter D 104 in the direction perpendicular to the (104) plane, respectively
And the ratio of the crystallite diameter D 110 in the direction perpendicular to the (110) plane (D 10
4 / D 110 ), the former is D 104 / D 110 = 1 to 2
On the other hand, the latter has D 104 / D 110 = 0.5 to 0.9. This indicates that the acicular α-ferric oxide crystallites according to the present invention grow well in the C-axis direction, and the major axis direction of the particles is considered to be the [001] direction.
【００３５】本発明による針状α−酸化第二鉄を公知の
方法によつて針状γ−酸化第二鉄に変態させた場合、そ
の長軸方向は〔１１１〕方向になると考えられ、γ−酸
化第二鉄の結晶磁気異方性による磁化容易方向と一致す
ることになり、α−ＦｅＯＯＨから得られる針状γ−酸
化第二鉄の長軸方向が〔１１０〕方向であることと比較
して、保磁力の点で有利である。When the acicular α-ferric oxide according to the present invention is transformed into acicular γ-ferric oxide by a known method, the major axis direction is considered to be the [111] direction. -Comparing with the direction of easy magnetization due to the crystal magnetic anisotropy of ferric oxide, the major axis direction of the acicular γ-ferric oxide obtained from α-FeOOH is the [110] direction. This is advantageous in terms of coercive force.
【００３６】また、本発明の製造方法によつて得られる
針状α−酸化第二鉄は、粒度分布にすぐれており、公知
の方法を用いて針状γ−酸化第二鉄に変態させ、磁気テ
ープを作成した場合に、その反転磁界分布（ｎ−ＳＦ
Ｄ）が小さい値となる。更に、製造条件の調整によつ
て、その針状比が１０〜１５という従来にない大きさを
有する針状α−酸化第二鉄を得ることができ、針状γ−
酸化第二鉄に変態させた際の保磁力の発現に有利であ
る。Further, the acicular α-ferric oxide obtained by the production method of the present invention has an excellent particle size distribution and is transformed into acicular γ-ferric oxide by a known method. When a magnetic tape is created, its switching field distribution (n-SF
D) has a small value. Further, by adjusting the production conditions, needle-shaped α-ferric oxide having a needle-shaped ratio of 10 to 15 which is unprecedented can be obtained, and needle-shaped γ-
It is advantageous in developing coercive force when transformed into ferric oxide.
【００３７】[0037]
【実施例】以下に、本発明を実施例に基づいて説明す
る。尚、懸濁液中の塩素イオン量は、硝酸銀を用いた滴
定法によつて求め、また、ＳｉＯ2 量はモリブデンブル
ーによる吸光光度法により求めた。得られた針状α−酸
化第二鉄については、比表面積、平均針状比、Ｄ104 、
Ｄ 110 及びＤ104 ／Ｄ110 を求めた。比表面積はＢＥＴ
法で測定し、針状比は、電子顕微鏡写真から５０個の粒
子の針状比を求めて平均した。結晶子径は、Ｘ線回折装
置（理学電機製）を用い、得られたプロファイルから半
価幅を求め、シェラーの式に代入して算出した。尚、線
源としてはＣｕＫα線を用い、フィルターとしてＮｉを
使用した。EXAMPLES The present invention will be described below based on examples.
It The amount of chloride ions in the suspension is measured using silver nitrate.
Obtained by a conventional method, and SiO2Amount is molybdenum bull
It was determined by the spectrophotometric method. Obtained acicular α-acid
For ferric chloride, specific surface area, average acicular ratio, D104,
D 110And D104/ D110I asked. Specific surface area is BET
Method, the acicular ratio is 50 particles from electron micrograph
The needle ratio of the pups was calculated and averaged. Crystallite size is X-ray diffractometer
Half (from Rigaku Denki)
The price range was calculated and substituted into Scherrer's formula. The line
CuKα ray is used as the source, and Ni is used as the filter.
used.
【００３８】更に、得られた針状α−酸化第二鉄を公知
の方法で還元、酸化し、針状γ−酸化第二鉄を得、これ
を用いて磁気テープを作成した。針状γ−酸化第二鉄に
ついては、保持力と飽和磁化量を測定し、磁気テープに
ついては、反転磁界分布をＶＳＭを用いて測定した。磁
気テープの製造条件は以下のとおりである。即ち、針状
γ−酸化第二鉄粉末１００重量部をニトロセルロース５
重量部、塩化ビニル−酢酸ビニル共重合体樹脂2.５重量
部、ウレタン樹脂１7.５重量部及び溶剤２５３重量部か
らなる樹脂溶液に混合し、分散させて、磁性塗料を作成
した。この磁性塗料をポリエステルフィルム上に塗布
し、磁場配向をかけ、乾燥させて、約５μｍの塗膜（磁
性層）を有する磁気テープを得た。Further, the obtained acicular α-ferric oxide was reduced and oxidized by a known method to obtain acicular γ-ferric oxide, which was used to prepare a magnetic tape. For the acicular γ-ferric oxide, the coercive force and the saturation magnetization were measured, and for the magnetic tape, the reversal magnetic field distribution was measured using VSM. The manufacturing conditions of the magnetic tape are as follows. That is, 100 parts by weight of acicular γ-ferric oxide powder was added to nitrocellulose 5
A magnetic paint was prepared by mixing and dispersing in a resin solution consisting of 2.5 parts by weight of vinyl chloride-vinyl acetate copolymer resin, 17.5 parts by weight of urethane resin and 253 parts by weight of solvent. This magnetic paint was applied onto a polyester film, subjected to magnetic field orientation, and dried to obtain a magnetic tape having a coating film (magnetic layer) of about 5 μm.
【００３９】実施例１〜４及び比較例１、２ 塩化第二鉄結晶をイオン交換水（ＳｉＯ2 量0.１ｐｐ
ｍ）に溶解し、鉄濃度１2.７ｇ／リットルの水溶液を調
製した。別に、水酸化ナトリウムをイオン交換水に溶解
し、濃度２００ｇ／リットルの水酸化ナトリウム水溶液
を調製した。塩化第二鉄水溶液4.４リットルを攪拌しな
がら、水酸化ナトリウム水溶液をｐＨが8.５になるまで
徐々に添加し、赤褐色の水酸化第二鉄の懸濁液を得た。
中和中のスラリーの温度は１０℃に保持した。このよう
にして得られた水酸化第二鉄の懸濁液について、濾過、
リパルブ水洗及び濾過を繰り返した後、得られたケーキ
から、水酸化第二鉄を鉄として１6.７ｇ採取し、イオン
交換水中に分散させて、懸濁液0.５リットルを得た。こ
の懸濁液のｐＨを7.５にし、７０℃に昇温後、３時間攪
拌して、熟成した。Examples 1 to 4 and Comparative Examples 1 and 2 Ferric chloride crystals were deionized water (SiO 2 amount 0.1 pp).
m) to prepare an aqueous solution having an iron concentration of 12.7 g / liter. Separately, sodium hydroxide was dissolved in ion-exchanged water to prepare a sodium hydroxide aqueous solution having a concentration of 200 g / liter. While stirring 4.4 liters of ferric chloride aqueous solution, sodium hydroxide aqueous solution was gradually added until pH reached 8.5 to obtain a reddish brown ferric hydroxide suspension.
The temperature of the slurry during neutralization was kept at 10 ° C. The suspension of ferric hydroxide thus obtained was filtered,
After repeating the reparb washing with water and filtration, 16.7 g of ferric hydroxide as iron was collected from the obtained cake and dispersed in ion-exchanged water to obtain 0.5 liter of a suspension. The pH of this suspension was adjusted to 7.5, the temperature was raised to 70 ° C., and the mixture was stirred for 3 hours for aging.
【００４０】この熟成を施した懸濁液にアミノトリ（メ
チレンホスホン酸）0.６３ｇを添加し、ｐＨを１0.０に
調整した後、密閉容器に仕込み、攪拌しながら、１５０
℃に昇温し、９０分間攪拌して、水熟反応を行つた。反
応終了後、冷却し、常法にて、濾過、水洗、乾燥し、針
状α−酸化第二鉄を得た。これとは別に、使用水のＳｉ
Ｏ2 濃度及び水洗の程度を変えて、塩素イオン濃度及び
ＳｉＯ2 濃度の異なる５つの懸濁液各0.５リットルを調
製し、上記と同様にして、針状α−酸化第二鉄を得た。
結果を表１に示す。After adding 0.63 g of aminotri (methylenephosphonic acid) to the aged suspension to adjust the pH to 10.0, the mixture was placed in a closed container and stirred at 150
The temperature was raised to 0 ° C. and the mixture was stirred for 90 minutes to carry out a water maturation reaction. After completion of the reaction, the mixture was cooled, filtered, washed with water and dried by a conventional method to obtain acicular α-ferric oxide. Separately from this, the water used is Si
0.5 liters of each of 5 suspensions having different chlorine ion concentrations and SiO 2 concentrations were prepared by changing the O 2 concentration and the degree of washing with water, and needle-shaped α-ferric oxide was obtained in the same manner as above. It was
The results are shown in Table 1.
【００４１】実施例５、６及び比較例３ 熟成温度を５０℃、８５℃、２０℃とした以外は、実施
例１と同様の操作を行つて、３種の針状α−酸化第二鉄
を得た。結果を表２に示す。Examples 5 and 6 and Comparative Example 3 Three kinds of needle-like α-ferric oxides were prepared in the same manner as in Example 1 except that the aging temperatures were 50 ° C, 85 ° C and 20 ° C. Got The results are shown in Table 2.
【００４２】実施例７、８及び比較例４ 中和温度を５℃、２０℃、５０℃にした以外は、実施例
１と同様の操作を行つて、３種の針状α−酸化第二鉄を
得た。結果を表３に示す。Examples 7 and 8 and Comparative Example 4 The same operation as in Example 1 was carried out except that the neutralization temperature was changed to 5 ° C., 20 ° C. and 50 ° C. Got the iron. The results are shown in Table 3.
【００４３】比較例５ 硫酸第一鉄とアルカリを用いて水酸化第一鉄の懸濁液を
調製し、これに空気を吹き込んで、針状α−ＦｅＯＯＨ
を製造し、更に、これを６５０℃で１時間加熱脱水し
て、針状α−酸化第二鉄を得た。この針状α−酸化第二
鉄の比表面積は３8.０ｍ2 ／ｇ、針状比は１１、Ｄ104
は１６０オングストローム、Ｄ110 は２５４オングスト
ローム、Ｄ104 ／Ｄ110は0.６３であつた。針状γ−酸
化第二鉄の保磁力は３９２（Ｏｅ）、飽和磁化量は６9.
５（ｅｍｕ／ｇ）であり、磁気テープの反転磁界分布は
0.４０であつた。Comparative Example 5 A suspension of ferrous hydroxide was prepared using ferrous sulfate and an alkali, and air was blown into the suspension to form needle-shaped α-FeOOH.
Was further produced, and this was further heated and dehydrated at 650 ° C. for 1 hour to obtain acicular α-ferric oxide. The acicular α-ferric oxide has a specific surface area of 38.0 m 2 / g, an acicular ratio of 11, D 104
Was 160 Å, D 110 was 254 Å, and D 104 / D 110 was 0.63. The acicular γ-ferric oxide has a coercive force of 392 (Oe) and a saturation magnetization of 69.
5 (emu / g), and the switching field distribution of the magnetic tape is
It was 0.40.
【００４４】[0044]
【表１】 [Table 1]
【００４５】[0045]
【表２】 [Table 2]
【００４６】[0046]
【表３】 [Table 3]
【００４７】[0047]
【発明の効果】本発明の方法による針状α−酸化第二鉄
は、空孔を有せず、独立性にすぐれ、特に、粒度分布に
すぐれているので、これを原料として得られる針状γ−
酸化第二鉄を用いれば、反転磁界分布（ｎ−ＳＦＤ）の
小さい磁気テープを得ることができる。更に、製造条件
を調整することによつて、針状比にすぐれる針状α−酸
化第二鉄を得ることができ、磁気記録用針状γ−酸化第
二鉄の原料として好適に用いることができる。The needle-shaped α-ferric oxide obtained by the method of the present invention has no pores, is excellent in independence, and is particularly excellent in particle size distribution. γ-
If ferric oxide is used, a magnetic tape having a small switching field distribution (n-SFD) can be obtained. Furthermore, by adjusting the production conditions, acicular α-ferric oxide having an excellent acicular ratio can be obtained, which is preferably used as a raw material for acicular γ-ferric oxide for magnetic recording. You can
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山田 洋一 福島県いわき市泉町下川字田宿110 堺化 学工業株式会社小名浜事業所内 (72)発明者 和田 瑞穂 福島県いわき市泉町下川字田宿110 堺化 学工業株式会社小名浜事業所内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoichi Yamada 110 Tadashi, Shimokawa, Izumi-cho, Iwaki-shi, Fukushima Inside the Onahama Plant, Sakai Kagaku Kogyo Co., Ltd. (72) Mizuho Wada 110 Tadashi-juku, Shimokawa, Iwaki, Iwaki, Fukushima Prefecture Sakai Kagaku Kogyo Co., Ltd., Onahama Plant
Claims (2)
と（１１０）面に垂直方向の結晶子径Ｄ110 の比Ｄ104
／Ｄ110 が１〜２であり、平均針状比が１０〜１５であ
り、更に、比表面積が２０〜４０m2／ｇであることを特
徴とする針状α−酸化第二鉄。1. A crystallite diameter D 104 perpendicular to the (104) plane.
And the ratio D 104 of the crystallite diameter D 110 in the direction perpendicular to the (110) plane
/ D 110 is 1 to 2, an average acicular ratio is 10 to 15, and a specific surface area is 20 to 40 m 2 / g, and acicular α-ferric oxide.
液の温度を３０℃以下に保ちながら、ｐＨが７〜１０に
なるまで添加して、水酸化第二鉄の懸濁液を得、これを
濾過、水洗後、再懸濁して、得られた再懸濁液中のＳｉ
Ｏ2 量を６０ｐｐｍ以下とし、且つ、原料第二鉄塩に由
来するアニオン量を２０００ｐｐｍ以下とした後、この
水酸化第二鉄の懸濁液を４０〜１００℃にて熟成し、次
いで、この懸濁液に結晶化制御剤を加えて、水熱反応を
行なうことを特徴とする針状α−酸化第二鉄の製造方
法。2. A ferric hydroxide suspension is prepared by adding an aqueous alkaline solution to an aqueous solution of ferric salt while maintaining the temperature of the neutralizing solution at 30 ° C. or lower until the pH reaches 7 to 10. Obtained, filtered, washed with water and resuspended to obtain Si in the obtained resuspension.
After setting the amount of O 2 to 60 ppm or less and the amount of anions derived from the ferric salt of raw material to 2000 ppm or less, the suspension of ferric hydroxide was aged at 40 to 100 ° C., and then, A method for producing needle-like α-ferric oxide, which comprises adding a crystallization controlling agent to a suspension and carrying out a hydrothermal reaction.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6017586A JPH07223822A (en) | 1994-02-14 | 1994-02-14 | Acicular alpha-ferric oxide and production thereof |
| DE69426813T DE69426813T2 (en) | 1993-12-30 | 1994-12-29 | Fine-particle acicular alpha-iron-III-oxide and manufacturing process |
| US08/368,203 US5569445A (en) | 1993-12-30 | 1994-12-29 | Fine acicular α-ferric oxide and production thereof |
| EP94120879A EP0667607B9 (en) | 1993-12-30 | 1994-12-29 | Fine acicular alpha-ferric oxide and production thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6017586A JPH07223822A (en) | 1994-02-14 | 1994-02-14 | Acicular alpha-ferric oxide and production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07223822A true JPH07223822A (en) | 1995-08-22 |
Family
ID=11948015
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6017586A Pending JPH07223822A (en) | 1993-12-30 | 1994-02-14 | Acicular alpha-ferric oxide and production thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07223822A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006182604A (en) * | 2004-12-28 | 2006-07-13 | Catalysts & Chem Ind Co Ltd | Method for producing metal oxide sol and metal oxide sol |
| KR100906421B1 (en) * | 2007-09-06 | 2009-07-09 | 경북대학교 산학협력단 | A Method for Preparing Iron Oxide Particles for Improved Performance of Membrane Separation, and Advanced Water Treatment using the Iron Oxide Particles obtained |
-
1994
- 1994-02-14 JP JP6017586A patent/JPH07223822A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006182604A (en) * | 2004-12-28 | 2006-07-13 | Catalysts & Chem Ind Co Ltd | Method for producing metal oxide sol and metal oxide sol |
| KR100906421B1 (en) * | 2007-09-06 | 2009-07-09 | 경북대학교 산학협력단 | A Method for Preparing Iron Oxide Particles for Improved Performance of Membrane Separation, and Advanced Water Treatment using the Iron Oxide Particles obtained |
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