JPH0351660B2 - - Google Patents
Info
- Publication number
- JPH0351660B2 JPH0351660B2 JP61150732A JP15073286A JPH0351660B2 JP H0351660 B2 JPH0351660 B2 JP H0351660B2 JP 61150732 A JP61150732 A JP 61150732A JP 15073286 A JP15073286 A JP 15073286A JP H0351660 B2 JPH0351660 B2 JP H0351660B2
- Authority
- JP
- Japan
- Prior art keywords
- cobalt
- coercive force
- iron oxide
- aqueous solution
- add
- 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.)
- Expired - Lifetime
Links
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 48
- 229910017052 cobalt Inorganic materials 0.000 claims description 25
- 239000010941 cobalt Substances 0.000 claims description 25
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 25
- 239000007864 aqueous solution Substances 0.000 claims description 19
- 230000005291 magnetic effect Effects 0.000 claims description 16
- 229910001566 austenite Inorganic materials 0.000 claims description 15
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 14
- 239000002245 particle Substances 0.000 claims description 14
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 8
- 150000001868 cobalt Chemical class 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 7
- 239000003513 alkali Substances 0.000 claims description 6
- 230000005294 ferromagnetic effect Effects 0.000 claims description 6
- -1 iron ions Chemical class 0.000 claims description 6
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000009835 boiling Methods 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims 1
- 239000006247 magnetic powder Substances 0.000 description 17
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 8
- 230000005415 magnetization Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 238000011282 treatment Methods 0.000 description 8
- 229910001448 ferrous ion Inorganic materials 0.000 description 7
- 238000003756 stirring Methods 0.000 description 6
- 235000011121 sodium hydroxide Nutrition 0.000 description 5
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 229960002089 ferrous chloride Drugs 0.000 description 4
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229910001631 strontium chloride Inorganic materials 0.000 description 3
- AHBGXTDRMVNFER-UHFFFAOYSA-L strontium dichloride Chemical compound [Cl-].[Cl-].[Sr+2] AHBGXTDRMVNFER-UHFFFAOYSA-L 0.000 description 3
- 239000012670 alkaline solution Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- IIZPXYDJLKNOIY-JXPKJXOSSA-N 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine Chemical compound CCCCCCCCCCCCCCCC(=O)OC[C@H](COP([O-])(=O)OCC[N+](C)(C)C)OC(=O)CCC\C=C/C\C=C/C\C=C/C\C=C/CCCCC IIZPXYDJLKNOIY-JXPKJXOSSA-N 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 1
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 1
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- 229920002433 Vinyl chloride-vinyl acetate copolymer Polymers 0.000 description 1
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 description 1
- 229910001626 barium chloride Inorganic materials 0.000 description 1
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940044175 cobalt sulfate Drugs 0.000 description 1
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 150000002505 iron Chemical class 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- 229940067606 lecithin Drugs 0.000 description 1
- 235000010445 lecithin Nutrition 0.000 description 1
- 239000000787 lecithin Substances 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920006267 polyester film Polymers 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 159000000008 strontium salts Chemical class 0.000 description 1
Landscapes
- Compounds Of Iron (AREA)
- Hard Magnetic Materials (AREA)
Description
（産業上の利用分野）
本発明は酸化鉄強磁性粉末の製造に係り、より
詳細には、高記録密度が可能なコバルト含有酸化
鉄強磁性粉末の製造方法に関する。
（従来の技術及び解決しようとする問題点）
従来より、磁気記録用磁性粉としては、形状異
方性により高保磁力を有する針状γ−Fe2O3粒子
が用いられていたが、近年、更に高記録密度が可
能な高保磁力の磁気記録用磁性粉が要求されるよ
うになり、コバルトを含有する酸化鉄磁性粉末の
研究が盛んに行われている。
ところで、従来、コバルト含有γ−Fe2O3粒子
の製造方法としてはこれまで種々提案されている
が、その中でも有用なものの一つとしては、アル
カリ溶液中に針状γ−Fe2O3粒子を分散させ、こ
れにストロンチウム塩などのアルカリ土類金属塩
及びコバルト塩と第１鉄塩を加え、コバルト含有
γ−Fe2O3粒子とする方法がある。
この方法によつて得られるコバルト含有γ−
Fe2O3粒子は、粒子表面にコバルトを含有する酸
化鉄層が形成されているため、保磁力や単位重量
当たりの飽和磁化が増加するものの、分散性が悪
く、保磁力分布に劣り、また保磁力の経時変化も
大きいという欠点があつた。
本発明の目的は、上記従来技術の欠点を解消
し、高保磁力、高飽和磁化で、かつ、その保磁力
分布が均一で、分散性に優れ、しかも保磁力の経
時変化が殆どないコバルト含有酸化鉄強磁性粉末
を製造できる方法を提供することにある。
（問題点を解決するための手段）
上記目的を達成するため、本発明者は、コバル
ト含有酸化鉄磁性粉末の製造に関する従来の方法
についてその欠点をもたらす原因を検討分析した
ところ、従来法では、針状γ−Fe2O3粒子をまず
アルカリ溶液中に分散させた後、これにアルカリ
土類金属塩とコバルト塩と第１鉄塩を添加して、
コバルト含有γ−Fe2O3粒子の表面に第１鉄イオ
ン（Fe2+）を含む酸化鉄層を形成し、単位重量
当たりの飽和磁化σsの減少を抑制せんとしたもの
であると考えられるが、第１鉄イオンの添加量を
増やせばコバルト含有γ−Fe2O3の上記σsが増大
するものの、第１鉄イオン添加前に比べて保磁力
がかなり低下し、その保磁力の経時変化も大きく
なつてしまい、このように特に第１鉄塩の添加態
様に問題があるため、目的とする高保磁力強磁性
粉末が得られにくく、その保磁力分布が悪く、分
散性に劣り、保磁力の経時変化が大きくなつてし
まうことが判明した。
そこで、本発明者は、高保磁力、高飽和磁化
で、かつ、その保磁力分布が均一で分散性に優れ
た磁性粉を開発すべく鋭意研究の結果、針状γ−
Fe2O3粒子にまず添加量の1/2量の第１鉄塩を加
えた後、アルカリ土類金属塩、コバルト塩、次い
で残量の第１鉄塩を添加することで、保磁力の低
下を抑えると共に保磁力分布を均一にすることが
でき、目的の磁性粉を得ることが可能であること
を知見するに至り、本発明をなしたものである。
すなわち、本発明は、針状γ−Fe2O3粒子を
OH-イオン濃度が1.6〜3.0モル／になるような
量のアルカリを含有する水溶液中に分散させ、こ
れにまず添加量の1/2量の鉄塩を含む水溶液を加
え、次いでアルカリ土類金属塩水溶液、コバルト
塩水溶液を加えた後、残量の第１鉄塩を含む水溶
液を加え、非酸化性雰囲気中で該分散液の沸点以
下の温度で処理することにより、針状γ−Fe2O3
粒子表面に第１鉄イオンを含む酸化鉄層とコバル
ト及びアルカリ土類金属を含有する酸化鉄層の２
層を形成せしめることを特徴とする磁気記録用強
磁性粉末の製造方法を要旨とするものである。
以下に本発明を実施例に基づいて詳細に説明す
る。
前述の如く、要するに、本発明の最大の特徴
は、アルカリ土類金属塩を添加し、第１鉄塩を２
回に分けて添加することにあり、これによつて従
来法に比べ少量のコバルト添加量で特に保磁力が
高められたコバルト含有酸化鉄磁性粉末が得られ
るものである。これらの処理は沸点以下の温度で
行うが、処理温度が低くなるにつれて長時間の処
理が必要となるので、沸点近くのできるだけ高い
温度で処理することが好ましい。
本発明では、まず、核となる針状γ−Fe2O3粒
子をアルカリを含有する水溶液中に充分に分散さ
せるが、その際、アルカリ量はOH-イオン濃度
が1.6〜3.0モル／になるような量を添加する必
要がある。アルカリとしては水酸化ナトリウム、
水酸化カリウム、水酸化リチウムなどを使用する
ことができる。アルカリ添加量が上記範囲外で
は、次工程で所要量の第１鉄塩を添加しても核晶
表面に狙いとする第１鉄イオンを含む酸化鉄層を
効果的に形成することがむずかしくなる。
次に、上記分散液を適宜温度（例、90℃）まで
上昇した後、添加量の1/2量の第１鉄塩を添加し
て所要時間（例、30分間）撹拌し、アルカリ土類
金属塩を含む水溶液を添加し、更に昇温（例、
100℃）してコバルト塩を含む水溶液を添加し、
所要時間（例、７時間）充分撹拌する。第１鉄塩
としては塩化第１鉄、硫酸第１鉄などを使用する
ことができ、アルカリ土類金属塩としては塩化ス
トロンチウムのほか、塩化バリウム、塩化カルシ
ウムなどを、またコバルト塩としては塩化コバル
ト、硫酸コバルトなどを使用することができる。
その後、残量の第１鉄塩を含む水溶液を加え、
所要時間（例、１時間）撹拌する。
なお、これらの処理、特に残量の第１鉄塩を添
加する前後では、空気の混入を防止する必要があ
ることから、非酸化性雰囲気中で行う。
このような工程によれば、針状γ−Fe2O3の核
晶の表面に第１鉄イオンを含有する酸化鉄層とコ
バルト及びアルカリ土類金属を含有する酸化鉄層
の２層が形成されるので、高い飽和磁化を有し、
高保磁力で、その保磁力分布が均一で、しかも保
磁力の経時変化が殆どなく、分散性にも優れたコ
バルト含有酸化鉄磁性粉末が得られる。
次に本発明の一実施例を示す。なお、本発明は
本実施例に限定されるものではないことは云うま
でもない。
（実施例）
常法により製造した針状γ−Fe2O3粉末（保磁
力：370Oe、飽和磁化：74emu／ｇ）1300ｇを、
９の水に1200ｇのNaOHを溶解させた苛性ソ
ーダ水溶液に加え、充分に分散させた後、この分
散液の温度を90℃まで昇温して塩化第１鉄100ｇ
を含む水溶液500mlを加えて30分間撹拌し、塩化
ストロンチウム20ｇを含む水溶液100ml添加して
更に昇温し、100℃で塩化コバルト105ｇを含む水
溶液900mlを添加し、可及的に空気の混入を防止
しながら、この温度を保持したまま撹拌を続け、
１時間後、３時間後、５時間後及び７時間後にそ
れぞれ約30mlの試料を採取した。７時間後の試料
採取後、塩化第１鉄100ｇを含む水溶液500mlを添
加し、更に１時間撹拌して反応を終了した。採取
した各試料及び反応終了後のスラリーを充分に水
洗し、脱水、乾燥した。得られた試料を振動試料
型磁力計（VSM−3S型、東英工業製）により外
部磁界10KOeで磁気特性を測定した。その結果
を第１表及び第１図に示す。
このように８時間反応処理後に得られたコバル
ト含有酸化鉄磁性粉末は、保磁力Hcが673Oe、
飽和磁化σsが77emu／ｇであつた。また、この磁
性粉を温度70℃で400時間保存した後の保磁力Hc
は682Oeであつた。
（比較例）
上記実施例と同様の針状γ−Fe2O3粉末1300ｇ
を、９の水に1200ｇのNaOHを溶解させた苛
性ソーダ水溶液に加え、充分に分散させた後、こ
の分散液の温度を90℃まで昇温して塩化ストロン
チウム20ｇを含む水溶液100ml添加し、100℃で塩
化コバルト105ｇを含む水溶液900mlを添加し、可
級的に空気の混入を防止しながら、この温度を保
持したまま撹拌を続け、１時間後、３時間後、５
時間後及び７時間後にそれぞれ約30mlの試料を採
取した。７時間後の試料採取後、塩化第１鉄200
ｇを含む水溶液１を添加し、更に１時間撹拌し
て反応を終了した。採取した各試料及び反応終了
後のスラリーを充分に水洗し、脱水、乾燥した。
得られた試料を上記実施例と同様の磁力計により
外部磁界10KOeで磁気特性を測定した。その結
果を第１表及び第１図に併記する。
このように８時間反応処理後に得られたコバル
ト含有酸化鉄磁性粉末は、保磁力Hcが659Oe、
飽和磁気σsが77emu／ｇであつた。また、この磁
性粉を温度70℃で400時間保存した後の保磁力Hc
は685Oeであつた。
(Industrial Field of Application) The present invention relates to the production of iron oxide ferromagnetic powder, and more particularly to a method of producing cobalt-containing iron oxide ferromagnetic powder that enables high recording density. (Prior art and problems to be solved) Acicular γ-Fe 2 O 3 particles, which have a high coercive force due to shape anisotropy, have traditionally been used as magnetic powder for magnetic recording, but in recent years, Furthermore, magnetic powder for magnetic recording with high coercive force capable of high recording density is required, and research on iron oxide magnetic powder containing cobalt is being actively conducted. By the way, various methods for producing cobalt-containing γ-Fe 2 O 3 particles have been proposed so far, but one of the most useful methods is to produce acicular γ-Fe 2 O 3 particles in an alkaline solution. There is a method of dispersing and adding an alkaline earth metal salt such as a strontium salt, a cobalt salt, and a ferrous salt to obtain cobalt-containing γ-Fe 2 O 3 particles. Cobalt-containing γ- obtained by this method
Fe 2 O 3 particles have an iron oxide layer containing cobalt formed on the particle surface, so although the coercive force and saturation magnetization per unit weight increase, they have poor dispersibility, poor coercive force distribution, and The drawback was that the coercive force changed significantly over time. The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a cobalt-containing oxide that has high coercive force, high saturation magnetization, uniform coercive force distribution, excellent dispersibility, and almost no change in coercive force over time. The object of the present invention is to provide a method for producing iron ferromagnetic powder. (Means for Solving the Problems) In order to achieve the above object, the present inventor investigated and analyzed the causes of the drawbacks of the conventional method for producing cobalt-containing iron oxide magnetic powder, and found that the conventional method: Acicular γ-Fe 2 O 3 particles are first dispersed in an alkaline solution, and then an alkaline earth metal salt, a cobalt salt, and a ferrous salt are added thereto.
It is thought that an iron oxide layer containing ferrous ions (Fe 2+ ) was formed on the surface of cobalt-containing γ-Fe 2 O 3 particles to suppress the decrease in saturation magnetization σs per unit weight. However, if the amount of ferrous ions added increases, the above σs of cobalt-containing γ-Fe 2 O 3 increases, but the coercive force decreases considerably compared to before adding ferrous ions, and the coercive force changes over time. Because of this problem, especially in the manner in which the ferrous salt is added, it is difficult to obtain the desired high coercive force ferromagnetic powder, and the coercive force distribution is poor, the dispersibility is poor, and the coercive force It was found that the change over time becomes large. Therefore, as a result of intensive research to develop magnetic powder with high coercive force, high saturation magnetization, uniform coercive force distribution, and excellent dispersibility, the present inventors found that acicular γ-
By first adding 1/2 the amount of ferrous salt to Fe 2 O 3 particles, then adding alkaline earth metal salt, cobalt salt, and then the remaining amount of ferrous salt, the coercive force can be increased. The present invention was made based on the discovery that it is possible to suppress the decrease and to make the coercive force distribution uniform, thereby obtaining the desired magnetic powder. That is, the present invention uses acicular γ-Fe 2 O 3 particles.
It is dispersed in an aqueous solution containing an amount of alkali such that the OH - ion concentration is 1.6 to 3.0 mol/h, an aqueous solution containing an iron salt in an amount of 1/2 of the added amount is added, and then an alkaline earth metal After adding the aqueous salt solution and the aqueous cobalt salt solution, an aqueous solution containing the remaining amount of ferrous salt is added and treated in a non-oxidizing atmosphere at a temperature below the boiling point of the dispersion to form acicular γ-Fe 2 O 3
An iron oxide layer containing ferrous ions on the particle surface and an iron oxide layer containing cobalt and alkaline earth metals.
The gist of the present invention is a method for producing ferromagnetic powder for magnetic recording, which is characterized by forming a layer. The present invention will be explained in detail below based on examples. As mentioned above, in short, the greatest feature of the present invention is that the alkaline earth metal salt is added and the ferrous salt is
This method allows cobalt-containing iron oxide magnetic powder with particularly high coercive force to be obtained with a smaller amount of cobalt added than in conventional methods. These treatments are performed at a temperature below the boiling point, but as the treatment temperature becomes lower, a longer treatment time becomes necessary, so it is preferable to perform the treatment at a temperature as high as possible near the boiling point. In the present invention, first, the acicular γ-Fe 2 O 3 particles serving as the core are sufficiently dispersed in an aqueous solution containing an alkali, and at that time, the amount of alkali is such that the OH - ion concentration is 1.6 to 3.0 mol/ It is necessary to add such amount. As an alkali, sodium hydroxide,
Potassium hydroxide, lithium hydroxide, etc. can be used. If the amount of alkali added is outside the above range, it will be difficult to effectively form the desired iron oxide layer containing ferrous ions on the surface of the nucleic crystal even if the required amount of ferrous salt is added in the next step. . Next, after raising the above dispersion to an appropriate temperature (e.g. 90°C), 1/2 of the amount of ferrous salt added and stirring for the required time (e.g. 30 minutes), alkaline earth Add an aqueous solution containing a metal salt and further raise the temperature (e.g.
100℃) and add an aqueous solution containing cobalt salt,
Stir thoroughly for the required time (eg, 7 hours). Ferrous salts include ferrous chloride and ferrous sulfate, alkaline earth metal salts include strontium chloride, barium chloride, calcium chloride, and cobalt salts such as cobalt chloride. , cobalt sulfate, etc. can be used. Then, add an aqueous solution containing the remaining amount of ferrous salt,
Stir for the required time (eg, 1 hour). These treatments, especially before and after adding the remaining amount of ferrous salt, are performed in a non-oxidizing atmosphere because it is necessary to prevent air from entering. According to such a process, two layers are formed on the surface of the acicular γ-Fe 2 O 3 nucleus crystal: an iron oxide layer containing ferrous ions and an iron oxide layer containing cobalt and alkaline earth metals. Therefore, it has a high saturation magnetization,
A cobalt-containing iron oxide magnetic powder with high coercive force, uniform coercive force distribution, almost no change in coercive force over time, and excellent dispersibility can be obtained. Next, an embodiment of the present invention will be described. It goes without saying that the present invention is not limited to this embodiment. (Example) 1300 g of acicular γ-Fe 2 O 3 powder (coercive force: 370 Oe, saturation magnetization: 74 emu/g) produced by a conventional method,
Add 1200g of NaOH to the aqueous solution of caustic soda dissolved in water from Step 9 and thoroughly disperse it, then raise the temperature of this dispersion to 90°C to dissolve 100g of ferrous chloride.
Add 500 ml of an aqueous solution containing cobalt chloride, stir for 30 minutes, add 100 ml of an aqueous solution containing 20 g of strontium chloride, further raise the temperature, and add 900 ml of an aqueous solution containing 105 g of cobalt chloride at 100°C to prevent air incorporation as much as possible. While maintaining this temperature, continue stirring.
Approximately 30 ml samples were taken each after 1 hour, 3 hours, 5 hours, and 7 hours. After collecting the sample after 7 hours, 500 ml of an aqueous solution containing 100 g of ferrous chloride was added, and the reaction was further stirred for 1 hour to complete the reaction. Each sample collected and the slurry after completion of the reaction were thoroughly washed with water, dehydrated, and dried. The magnetic properties of the obtained sample were measured using a vibrating sample magnetometer (Model VSM-3S, manufactured by Toei Kogyo) with an external magnetic field of 10 KOe. The results are shown in Table 1 and Figure 1. The cobalt-containing iron oxide magnetic powder obtained after 8 hours of reaction treatment had a coercive force Hc of 673 Oe,
The saturation magnetization σs was 77 emu/g. In addition, the coercive force Hc after storing this magnetic powder at a temperature of 70℃ for 400 hours is
was 682 Oe. (Comparative example) 1300 g of acicular γ-Fe 2 O 3 powder similar to the above example
was added to a caustic soda aqueous solution prepared by dissolving 1200 g of NaOH in water from Step 9 and thoroughly dispersed.Then, the temperature of this dispersion was raised to 90°C, 100ml of an aqueous solution containing 20g of strontium chloride was added, and the mixture was heated to 100°C. 900 ml of an aqueous solution containing 105 g of cobalt chloride was added, and stirring was continued while maintaining this temperature while preventing air from entering. After 1 hour, 3 hours, and 5 hours.
Approximately 30 ml samples were taken each time and after 7 hours. After 7 hours of sample collection, ferrous chloride 200
Aqueous solution 1 containing g was added thereto and stirred for an additional 1 hour to complete the reaction. Each sample collected and the slurry after completion of the reaction were thoroughly washed with water, dehydrated, and dried.
The magnetic properties of the obtained sample were measured using the same magnetometer as in the above example with an external magnetic field of 10 KOe. The results are also shown in Table 1 and Figure 1. The cobalt-containing iron oxide magnetic powder obtained after 8 hours of reaction treatment had a coercive force Hc of 659 Oe,
The saturation magnetism σs was 77 emu/g. In addition, the coercive force Hc after storing this magnetic powder at a temperature of 70℃ for 400 hours is
was 685 Oe.
【表】
上記実施例及び比較例で得られたコバルト含有
酸化鉄磁性粉末を用い、これに下記組成の成分を
添加して約48時間ボールミルで混練して磁性塗料
を調整した。
コバルト含有酸化鉄磁性粉 …75重量部
塩化ビニル−酢酸ビニル共重合体 …19 〃
ジオクチルフタレート …４ 〃
レシチン …２ 〃
トルエン …100 〃
メチルイソブチルケトン …100 〃
この磁性塗料を厚さ12μのポリエステルフイル
ム上に乾燥厚が約6μとなるように塗布し、磁場
配向を行いながら乾燥して磁気テープを製造し
た。得られた各磁気テープの角形比（Br／Bm）、
反転磁界分布（SFD）を測定したところ、第２
表に示す結果が得られた。[Table] Using the cobalt-containing iron oxide magnetic powder obtained in the above Examples and Comparative Examples, the following components were added and kneaded in a ball mill for about 48 hours to prepare a magnetic paint. Cobalt-containing iron oxide magnetic powder...75 parts by weight Vinyl chloride-vinyl acetate copolymer...19 Dioctyl phthalate...4 Lecithin...2 Toluene...100 Methyl isobutyl ketone...100 Apply this magnetic paint to a 12μ thick polyester film A magnetic tape was manufactured by coating the film on the surface to a dry thickness of about 6 μm and drying it while applying magnetic field orientation. The squareness ratio (Br/Bm) of each magnetic tape obtained,
When we measured the switching field distribution (SFD), we found that the second
The results shown in the table were obtained.
【表】
第２表により明らかなように、本発明法により
得られたコバルト含有酸化鉄磁性粉末を用いて製
造した磁気テープは、比較例による場合に比べ、
角形比及び反転磁界分布のいずれも優れており、
保磁力分布が均一で分散性も優れているほか、経
時変化も少ないことがわかる。
（発明の効果）
以上詳述したように、本発明によれば、針状γ
−Fe2O3の核晶表面に第１鉄イオンを含む酸化鉄
層とコバルトを含有する酸化鉄層の２層が形成さ
れるので、高保磁力、高飽和磁化で、かつ、その
保磁力分布が均一であると共に分散性に優れたコ
バルト含有酸化鉄磁性粉末を容易に、しかも少量
のコバルト添加量で経済的に製造することができ
る。したがつて、高品質の磁気記録用媒体の製造
を可能にするものである。[Table] As is clear from Table 2, the magnetic tape manufactured using the cobalt-containing iron oxide magnetic powder obtained by the method of the present invention has
Both the squareness ratio and reversal magnetic field distribution are excellent,
It can be seen that the coercive force distribution is uniform, the dispersibility is excellent, and there is little change over time. (Effects of the Invention) As detailed above, according to the present invention, the acicular γ
-Two layers are formed on the surface of the Fe 2 O 3 nucleus: an iron oxide layer containing ferrous ions and an iron oxide layer containing cobalt, resulting in high coercive force, high saturation magnetization, and a high coercive force distribution. A cobalt-containing iron oxide magnetic powder that is uniform and has excellent dispersibility can be easily and economically produced with a small amount of cobalt added. Therefore, it is possible to manufacture a high quality magnetic recording medium.
第１図はコバルト含有酸化鉄磁性粉末の保磁力
Hcと反応処理時間の関係を示す特性図である。
Figure 1 shows the coercive force of cobalt-containing iron oxide magnetic powder.
FIG. 3 is a characteristic diagram showing the relationship between Hc and reaction treatment time.
Claims (1)
〜3.0モル／になるような量のアルカリを含有
する水溶液中に分散させ、これにまず添加量の1/
２量の第１鉄塩を含む水溶液を加え、次いでアル
カリ土類金属塩水溶液、コバルト塩水溶液を加え
た後、残量の第１鉄塩を含む水溶液を加え、非酸
化性雰囲気中で該分散液の沸点以下の温度で処理
することにより、針状γ−Fe2O3粒子表面に第１
鉄イオンを含む酸化鉄層とコバルト及びアルカリ
土類金属を含有する酸化鉄層の２層を形成せしめ
ることを特徴とする磁気記録用強磁性粉末の製造
方法。1 OH - ion concentration of acicular γ-Fe 2 O 3 particles is 1.6
Disperse the alkali in an aqueous solution containing an amount of ~3.0 mol/ml, and then add 1/1/2 of the amount added.
Add an aqueous solution containing two amounts of ferrous salt, then add an aqueous alkaline earth metal salt solution and an aqueous cobalt salt solution, then add the remaining amount of an aqueous solution containing ferrous salt, and disperse in a non-oxidizing atmosphere. By treating at a temperature below the boiling point of the liquid, a first layer is formed on the surface of the acicular γ-Fe 2 O 3 particles.
A method for producing ferromagnetic powder for magnetic recording, comprising forming two layers: an iron oxide layer containing iron ions and an iron oxide layer containing cobalt and an alkaline earth metal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61150732A JPS638223A (en) | 1986-06-27 | 1986-06-27 | Production of ferromagnetic powder for magnetic recording |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61150732A JPS638223A (en) | 1986-06-27 | 1986-06-27 | Production of ferromagnetic powder for magnetic recording |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS638223A JPS638223A (en) | 1988-01-14 |
| JPH0351660B2 true JPH0351660B2 (en) | 1991-08-07 |
Family
ID=15503202
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61150732A Granted JPS638223A (en) | 1986-06-27 | 1986-06-27 | Production of ferromagnetic powder for magnetic recording |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS638223A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014027047A (en) * | 2012-07-25 | 2014-02-06 | Ricoh Co Ltd | Magnetic structure and method for manufacturing the same |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5939730A (en) * | 1982-08-30 | 1984-03-05 | Ishihara Sangyo Kaisha Ltd | Manufacture of ferromagnetic iron oxide |
| JPS59107924A (en) * | 1982-12-08 | 1984-06-22 | Ishihara Sangyo Kaisha Ltd | Manufacture of magnetic iron oxide powder containing cobalt |
| JPS59138312A (en) * | 1983-01-28 | 1984-08-08 | Ishihara Sangyo Kaisha Ltd | Manufacture of magnetic ferrous oxide powder containing cobalt |
| JPS6051242A (en) * | 1983-08-29 | 1985-03-22 | 三協アルミニウム工業株式会社 | Curtain wall |
| JPS61111508A (en) * | 1984-11-06 | 1986-05-29 | Showa Denko Kk | Manufacturing method for magnetic powder used in magnetic recording |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59500739A (en) * | 1983-04-12 | 1984-04-26 | メモレックス・コーポレーション | ferromagnetic recording material |
-
1986
- 1986-06-27 JP JP61150732A patent/JPS638223A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5939730A (en) * | 1982-08-30 | 1984-03-05 | Ishihara Sangyo Kaisha Ltd | Manufacture of ferromagnetic iron oxide |
| JPS59107924A (en) * | 1982-12-08 | 1984-06-22 | Ishihara Sangyo Kaisha Ltd | Manufacture of magnetic iron oxide powder containing cobalt |
| JPS59138312A (en) * | 1983-01-28 | 1984-08-08 | Ishihara Sangyo Kaisha Ltd | Manufacture of magnetic ferrous oxide powder containing cobalt |
| JPS6051242A (en) * | 1983-08-29 | 1985-03-22 | 三協アルミニウム工業株式会社 | Curtain wall |
| JPS61111508A (en) * | 1984-11-06 | 1986-05-29 | Showa Denko Kk | Manufacturing method for magnetic powder used in magnetic recording |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS638223A (en) | 1988-01-14 |
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