JPH01159826A - Ferromagnetic powder - Google Patents
Ferromagnetic powderInfo
- Publication number
- JPH01159826A JPH01159826A JP62319875A JP31987587A JPH01159826A JP H01159826 A JPH01159826 A JP H01159826A JP 62319875 A JP62319875 A JP 62319875A JP 31987587 A JP31987587 A JP 31987587A JP H01159826 A JPH01159826 A JP H01159826A
- Authority
- JP
- Japan
- Prior art keywords
- cobalt
- coercive force
- iron oxide
- magnetic powder
- oxide magnetic
- 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.)
- Pending
Links
- 239000000843 powder Substances 0.000 title abstract description 7
- 230000005294 ferromagnetic effect Effects 0.000 title description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 56
- 239000010941 cobalt Substances 0.000 claims abstract description 39
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 39
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000006247 magnetic powder Substances 0.000 claims abstract description 28
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 22
- 239000002245 particle Substances 0.000 claims abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 6
- 229910001429 cobalt ion Inorganic materials 0.000 abstract description 4
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 abstract description 4
- 150000001768 cations Chemical class 0.000 abstract description 3
- 239000011575 calcium Substances 0.000 description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 5
- 150000001868 cobalt Chemical class 0.000 description 4
- 230000005291 magnetic effect Effects 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 159000000007 calcium salts Chemical class 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical class [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 229940044175 cobalt sulfate Drugs 0.000 description 2
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 2
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 229960002089 ferrous chloride Drugs 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Landscapes
- Paints Or Removers (AREA)
- Magnetic Record Carriers (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は酸化鉄磁性粉末の表面にコバルトフェライト
層を形成したコバルト含有酸化鉄磁性粉末に関し、さら
に詳しくは、磁気記録媒体の記録素子として好適で保磁
力の安定性に優れた前記のコバルト含有酸化鉄磁性粉末
に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cobalt-containing iron oxide magnetic powder in which a cobalt ferrite layer is formed on the surface of the iron oxide magnetic powder, and more specifically, it is suitable as a recording element of a magnetic recording medium. The present invention relates to the cobalt-containing iron oxide magnetic powder having excellent coercive force stability.
〔従来の技術］
コバルトを含有する酸化鉄磁性粉末は、従来の磁気記録
媒体の記録素子として汎用されている酸化鉄磁性粉末に
比べ高保磁力を有し、なかでも酸化鉄磁性粉末の粒子表
面にコバルトフェライト層を形成させたものは、粒子内
部までコバルトイオンが固溶されたコバルト含有酸化鉄
磁性粉末に比べて、保磁力が比較的安定であるため、高
性能磁気記録媒体の有用な記録素子として広く使用され
ている。（特公昭５８−５２９２７号）〔発明が解決し
ようとする問題点〕
ところが、この種の粒子表面にコバルトフェライト層を
形成させたコバルト含有酸化鉄磁性粉末は、コバルトフ
ェライト層が厚くなったり、Ｆｅｔ＋／Ｆｅ３＊の値が
大きくなったり、あるいは粒子径が小さくなると、コバ
ルトフェライト層中でコバルトイオンや陽イオン空位が
動きやすくなって、保磁力の安定性が充分でな（なると
いう難点があり、特に、粒子径が０．３μｍ以下の微粒
子では、７００エルステッド以上の高保磁力にしようと
すると、３１’ ｅ２７ Ｆ ｅ３＊を０．０５以上と
しなければならず、このため保磁力が不安定になって、
経時的に保磁力が増大するという欠点がある。[Prior Art] Iron oxide magnetic powder containing cobalt has a higher coercive force than iron oxide magnetic powder commonly used as a recording element of conventional magnetic recording media. Products with a cobalt ferrite layer have relatively stable coercive force compared to cobalt-containing iron oxide magnetic powders in which cobalt ions are dissolved deep inside the particles, making them useful recording elements for high-performance magnetic recording media. It is widely used as (Japanese Patent Publication No. 58-52927) [Problems to be Solved by the Invention] However, with this type of cobalt-containing iron oxide magnetic powder in which a cobalt ferrite layer is formed on the particle surface, the cobalt ferrite layer becomes thick and Fe+ When the value of /Fe3* increases or the particle size decreases, cobalt ions and cation vacancies become more mobile in the cobalt ferrite layer, resulting in insufficient coercive force stability. In particular, in the case of fine particles with a particle diameter of 0.3 μm or less, in order to achieve a high coercive force of 700 Oe or more, 31' e27 Fe3* must be set to 0.05 or more, which causes the coercive force to become unstable. hand,
The drawback is that the coercive force increases over time.
この発明は、かかる現状に鑑み鋭意研究を重ねた結果な
されたもので、酸化鉄磁性粉末の表面にコバルトフェラ
イト層を形成した、保磁力が７００エルステッド以上、
粒子径が０．３μｍ以下で、Ｆｅｔ＋／Ｆｅ２＊が０．
０５以上のコバルト含有酸化鉄磁性粉末のコバルトフェ
ライト層中に、ＣａをＣｏに対して３重量％以上含ませ
ることによって、コバルトイオンや陽イオン空位を動き
に＜＜シ、保磁力を安定化して、経時的な保磁力の増大
を効果的に抑制したものである。This invention was made as a result of intensive research in view of the current situation, and consists of a cobalt ferrite layer formed on the surface of iron oxide magnetic powder, and a coercive force of 700 Oe or more.
The particle size is 0.3 μm or less, and Fet+/Fe2* is 0.
By including 3% or more of Ca relative to Co in the cobalt ferrite layer of the cobalt-containing iron oxide magnetic powder of . , which effectively suppresses the increase in coercive force over time.
この発明において、酸化鉄磁性粉末の表面のコバルトフ
ェライト層中に含まれるＣａは、コバルトフェライト層
中のＣｏに対して３重量％以上であることが好ましく、
Ｃｏに対して３重量％以上のＣａをコバルトフェライト
層中に含有させると、コバルトフェライト層中のＣａイ
オンによって、コバルトイオンや陽イオン空位が動きに
くくなり、保磁力が安定化して、保磁力の経時的な増大
が抑制される。そして、この種のコバルト含有酸化鉄磁
性粉末を使用して得られる磁気記録媒体の保磁力の安定
性も一段と向上される。これに対して、コバルトフェラ
イト層中に含まれるＣａがＣｏに対して３重量％より少
なくては、所期の効果が得られず、多いほどより保磁力
を安定化することができるが、３０重量％より多くなる
と、生成物の保磁力および飽和磁化量が低下するため好
ましくない。In this invention, it is preferable that Ca contained in the cobalt ferrite layer on the surface of the iron oxide magnetic powder is 3% by weight or more with respect to Co in the cobalt ferrite layer,
When Ca is contained in a cobalt ferrite layer in an amount of 3% by weight or more based on Co, the Ca ions in the cobalt ferrite layer make it difficult for cobalt ions and cation vacancies to move, stabilizing the coercive force and increasing the coercive force. Increase over time is suppressed. Furthermore, the stability of the coercive force of the magnetic recording medium obtained using this type of cobalt-containing iron oxide magnetic powder is further improved. On the other hand, if the amount of Ca contained in the cobalt ferrite layer is less than 3% by weight relative to Co, the desired effect cannot be obtained. If it exceeds % by weight, it is not preferable because the coercive force and saturation magnetization of the product decrease.
このように、Ｃｏに対して３重量％以上のＣａを含有さ
せたコバルトフェライト層の形成は、酸化鉄磁性粉末を
、コバルト塩および第一鉄塩とアルカリとを含む水溶液
中で反応させる際、同時にカルシウム塩を添加して反応
させることによって形成され、カルシウム塩の添加量を
調節することによって、コバルトフェライト層中のＣａ
含有量が調整される。As described above, the formation of a cobalt ferrite layer containing 3% by weight or more of Ca relative to Co can be achieved by reacting iron oxide magnetic powder in an aqueous solution containing a cobalt salt, a ferrous salt, and an alkali. It is formed by simultaneously adding calcium salt and reacting, and by adjusting the amount of calcium salt added, Ca in the cobalt ferrite layer can be
The content is adjusted.
ここで用いられるカルシウム塩としては、塩化カルシウ
ム、硫酸カルシウム、硝酸カルシウムなどの水可溶性塩
などが好適なものとして使用される。As the calcium salt used here, water-soluble salts such as calcium chloride, calcium sulfate, and calcium nitrate are preferably used.
また、コバルト塩としては塩化コバルト、硫酸コバルト
、硝酸コバルトなどが好適なものとして使用され、第一
鉄塩としては塩化第一鉄、硫酸第一鉄、硝酸第一鉄など
が好ましく使用される。Further, cobalt salts such as cobalt chloride, cobalt sulfate, and cobalt nitrate are preferably used, and ferrous salts such as ferrous chloride, ferrous sulfate, and ferrous nitrate are preferably used.
アルカリとしては、通常、苛性ソーダが用いら゛・
れ、その好適な配合量は、コバルト塩と第一鉄
塩との総量に対して当量以上とするのが好ましい。Caustic soda is usually used as the alkali.
The suitable amount of the cobalt salt and the ferrous salt is preferably equal to or more than the total amount of the cobalt salt and the ferrous salt.
出発原料として用いる酸化鉄磁性粉末は、たとえば、７
ＦｅｚＯｓ粉末、Ｆｅ５０．粉末およびγ−Ｆｅ、Ｏ，
を水素気流中で部分還元することによって得られるγ−
Ｆｅ、Ｏ，とＦｅ、Ｏ。The iron oxide magnetic powder used as a starting material is, for example, 7
FezOs powder, Fe50. Powder and γ-Fe, O,
γ- obtained by partial reduction in a hydrogen stream
Fe, O, and Fe, O.
との中間の酸化状態の酸化鉄磁性粉末等粒子径が０．３
μｍ以下のものが好適なものとして使用される。Iron oxide magnetic powder with an oxidation state intermediate between the particle size of 0.3
A material having a diameter of .mu.m or less is preferably used.
次に、この発明の実施例について説明する。 Next, embodiments of the invention will be described.
実施例１ 長軸径０．２０μｍ、軸比８の針状１−Ｆｅ２Ｏ。Example 1 Acicular 1-Fe2O with a major axis diameter of 0.20 μm and an axial ratio of 8.
粉末３００ｇを２０ｆｆｉの純水に分散させ、これに硫
酸コバルト５７２．５ ｇと硫酸第１鉄２２６５ｇおよ
び塩化カルシウム１６．６ ｇとを加えて溶解させた、
これに１ｏＩｌの純水に溶解させたＮａＯＨ３２１５ｇ
を加えて撹拌しながら４５℃の温度で８時間反応させた
。しかる後、水洗、脱水、乾燥して、ＣａをＣｏに対し
て５．０重量％含有したコバルトフェライト層を粒子表
面に形成したコバルト含有酸化鉄磁性粉末を得た。この
ようにして得られたコバルト含有酸化鉄磁性粉末は、保
磁力がが８５０エルステツドで、Ｆｅ”／Ｆｅ３＋は分
析の結果０．０９０であった。300 g of powder was dispersed in 20ffi of pure water, and 572.5 g of cobalt sulfate, 2265 g of ferrous sulfate, and 16.6 g of calcium chloride were added and dissolved.
3215g of NaOH dissolved in 1oIl of pure water
was added and reacted at a temperature of 45° C. for 8 hours while stirring. Thereafter, the powder was washed with water, dehydrated, and dried to obtain a cobalt-containing iron oxide magnetic powder in which a cobalt ferrite layer containing 5.0% by weight of Ca based on Co was formed on the particle surface. The thus obtained cobalt-containing iron oxide magnetic powder had a coercive force of 850 oersteds, and an analysis of Fe''/Fe3+ was 0.090.
比較例１
実施例１において、塩化カルシウムの添加を省いた以外
は実施例１と同様にして、カルシウムを含まないコバル
トフェライト層を粒子表面に形成したコバルト含有酸化
鉄磁性粉末を得た。このようにして得られたコバルト含
有酸化鉄磁性粉末は、保磁力が８３０エルステツドで、
Ｆｅ”／Ｆｅ１は分析の結果０．０８８であった。Comparative Example 1 A cobalt-containing iron oxide magnetic powder having a calcium-free cobalt ferrite layer formed on the particle surface was obtained in the same manner as in Example 1 except that the addition of calcium chloride was omitted. The cobalt-containing iron oxide magnetic powder thus obtained has a coercive force of 830 oersted,
Fe''/Fe1 was 0.088 as a result of analysis.
各実施例および比較例で得られたコバルト含有酸化鉄磁
性粉末について、保磁力の経時変化を調べた。保磁力の
経時変化は、各コバルト含有酸化鉄磁性粉末を内容量１
０ｍ１のガラス容器に入れ、真空ポンプで容器内の空気
を抜いた後、密封しＣ１６０°Ｃの温度で２週間保存し
、保存後、ガラス容器より取り出して保磁力を測定した
。そして、保存前の各コバルト含有酸化鉄磁性粉末の保
磁力と比較した。The cobalt-containing iron oxide magnetic powder obtained in each Example and Comparative Example was examined for changes in coercive force over time. The change in coercive force over time was determined when each cobalt-containing iron oxide magnetic powder was
The sample was placed in a 0 ml glass container, the air inside the container was removed using a vacuum pump, the container was sealed and stored at a temperature of 160° C. for 2 weeks. After storage, it was taken out from the glass container and its coercive force was measured. Then, the coercive force of each cobalt-containing iron oxide magnetic powder before storage was compared.
下記第１表はその結果である。Table 1 below shows the results.
第１表
〔発明の効果〕
上記第１表から明らかなように、この発明で得られたコ
バルトフェライト層にＣａをＣｏに対して３重量％以上
含をさせたコバルト含有酸化鉄磁性粉末（実施例１）は
、いずれも従来のコバルトフェライト層にＣａが存在し
ないコバルト含有酸化鉄磁性粉末（比較例１）に比し、
保磁力の経時的ム増大が少なく、このことから、この発
明で得られる強磁性粉末は保磁力の経時変化が小さく、
保磁力の安定性に優れていることがわかる。Table 1 [Effects of the Invention] As is clear from Table 1 above, the cobalt-containing iron oxide magnetic powder (implemented Example 1) is compared to the conventional cobalt-containing iron oxide magnetic powder (Comparative Example 1) in which no Ca is present in the cobalt ferrite layer.
There is little increase in coercive force over time, and therefore, the ferromagnetic powder obtained by this invention has a small change in coercive force over time.
It can be seen that the stability of coercive force is excellent.
特許出願人 日立マクセル株式会社Patent applicant: Hitachi Maxell, Ltd.
Claims (1)
成した、保磁力が７００エルステッド以上、粒子径が０
．３μｍ以下で、Ｆｅ＾２＾＋／Ｆｅ＾３＾＋）が０．
０５以上のコバルト含有酸化鉄磁性粉末において、コバ
ルトフェライト層中にＣａをＣｏに対して３重量％以上
含有させたことを特徴とする強磁性粉末1. A cobalt ferrite layer is formed on the surface of iron oxide magnetic powder, the coercive force is 700 Oe or more, and the particle size is 0.
．． 3μm or less, Fe^2^+/Fe^3^+) is 0.
05 or higher cobalt-containing iron oxide magnetic powder, characterized in that the cobalt ferrite layer contains 3% by weight or more of Ca based on Co.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62319875A JPH01159826A (en) | 1987-12-16 | 1987-12-16 | Ferromagnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62319875A JPH01159826A (en) | 1987-12-16 | 1987-12-16 | Ferromagnetic powder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01159826A true JPH01159826A (en) | 1989-06-22 |
Family
ID=18115209
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62319875A Pending JPH01159826A (en) | 1987-12-16 | 1987-12-16 | Ferromagnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01159826A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0468336A (en) * | 1990-07-10 | 1992-03-04 | Fuji Photo Film Co Ltd | Silver halide color photographic sensitive material having magnetic recording element |
-
1987
- 1987-12-16 JP JP62319875A patent/JPH01159826A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0468336A (en) * | 1990-07-10 | 1992-03-04 | Fuji Photo Film Co Ltd | Silver halide color photographic sensitive material having magnetic recording element |
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