JPH0516163B2 - - Google Patents
Info
- Publication number
- JPH0516163B2 JPH0516163B2 JP58026040A JP2604083A JPH0516163B2 JP H0516163 B2 JPH0516163 B2 JP H0516163B2 JP 58026040 A JP58026040 A JP 58026040A JP 2604083 A JP2604083 A JP 2604083A JP H0516163 B2 JPH0516163 B2 JP H0516163B2
- Authority
- JP
- Japan
- Prior art keywords
- cobalt
- iron oxide
- magnetic powder
- aqueous solution
- 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.)
- Expired - Lifetime
Links
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 90
- 239000006247 magnetic powder Substances 0.000 claims description 45
- 239000010941 cobalt Substances 0.000 claims description 34
- 229910017052 cobalt Inorganic materials 0.000 claims description 34
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 34
- 239000007864 aqueous solution Substances 0.000 claims description 24
- 150000001868 cobalt Chemical class 0.000 claims description 16
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 9
- 239000006185 dispersion Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 3
- -1 First Chemical compound 0.000 claims description 2
- 239000003513 alkali Substances 0.000 claims description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 229910001566 austenite Inorganic materials 0.000 description 6
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical class [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 5
- 229940044175 cobalt sulfate Drugs 0.000 description 5
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 5
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 5
- 235000003891 ferrous sulphate Nutrition 0.000 description 5
- 239000011790 ferrous sulphate Substances 0.000 description 5
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 235000011121 sodium hydroxide Nutrition 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 230000005415 magnetization Effects 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- IPCSVZSSVZVIGE-UHFFFAOYSA-N hexadecanoic acid Chemical compound CCCCCCCCCCCCCCCC(O)=O IPCSVZSSVZVIGE-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 229920002554 vinyl polymer Polymers 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-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
- 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
- 235000021314 Palmitic acid Nutrition 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 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
- 229920001577 copolymer Polymers 0.000 description 1
- 229960002089 ferrous chloride Drugs 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- WQEPLUUGTLDZJY-UHFFFAOYSA-N n-Pentadecanoic acid Natural products CCCCCCCCCCCCCCC(O)=O WQEPLUUGTLDZJY-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
- G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
- G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
- G11B5/70652—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides gamma - Fe2 O3
- G11B5/70668—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides gamma - Fe2 O3 containing a dopant
- G11B5/70673—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides gamma - Fe2 O3 containing a dopant containing Co
Description
この発明は磁気記録媒体の記録素子として好適
な保磁力分布の優れたコバルト含有酸化鉄磁性粉
末の製造方法に関する。
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するため、高性
能磁気記録媒体の記録素子として有用である。
このようなコバルト含有酸化鉄磁性粉末の製造
方法はこれまで種々提案されており、その代表的
な方法の１つとして、酸化鉄磁性粉末をコバルト
塩および第一鉄塩を含む水溶液中に分散させ、こ
れにアルカリ水溶液を加えて酸化鉄磁性粉末の粒
子表面にコバルトを含む酸化鉄層を形成させるも
のがある。また、他の方法として、酸化鉄磁性粉
末をアルカリ水溶液中に分散させ、これにコバル
ト塩および第一鉄塩を含む水溶液を加えて、酸化
鉄磁性粉末の粒子表面にコバルトを含む酸化鉄層
を形成させるものがある。
ところが、この従来の方法では、まず、コバル
ト塩および第一鉄塩を溶解させた水溶液中に酸化
鉄磁性粉末を分散させ、しかる後、アルカリ水溶
液を加えて反応させているため、反応液が酸性側
からアルカリ性側に移行する際に溶存酸素により
コバルトフエライトの新生核が生じたりする場合
があり、また、たとえ酸化鉄磁性粉末をアルカリ
水溶液中に分散させ、これにコバルト塩および第
一鉄塩を含む水溶液を加える場合であつても、多
量のコバルト塩および第一鉄塩を使用して高保磁
力のコバルト含有酸化鉄磁性粉末を得ようとする
と、反応が不均一になつてコバルトを均一に含む
酸化鉄層が形成されず、その結果得られるコバル
ト含有酸化鉄磁性粉末は保磁力分布が悪く、この
磁性粉末を使用して得られる磁気記録媒体は消去
特性に劣り、また充分な出力が得られないという
難点があつた。
この発明者らはかかる現状に鑑み鋭意研究を重
ねた結果、まず、アルカリ水溶液中に酸化鉄磁性
粉末を分散させ、次いでこの分散液中にコバルト
塩および第一鉄塩の水溶液を２回以上にわけて添
加して反応させれば、反応は最初からアルカリ性
側で行われるためコバルトフエライトの新生核が
生じたりすることもなく、またコバルト塩および
第一鉄塩の水溶液の添加を２回以上に分けて行う
ことにより反応が均一に行えて保磁力分布の非常
に良好なコバルト含有酸化鉄磁性粉末が得られ、
従来の欠点が全て解消されることを見いだし、こ
の発明をなすに至つた。
この発明において、出発原料として用いる酸化
鉄磁性粉末は、針状のたとえば、γ−Fe2O3粉
末、Fe3O4粉末およびγ−Fe2O3を水素気流中で
部分還元することによつて得られるγ−Fe2O3と
Fe3O4との中間の酸化状態の酸化鉄磁性粉末等が
好適なものとして使用される。これらの酸化鉄磁
性粉末は、まず、アルカリ水溶液中に分散させ、
次いでこの分散液にコバルト塩および第一鉄塩の
水溶液を添加して反応させるのが好ましく、最初
にアルカリ水溶液中に分散させると、反応が終始
アルカリ性側で行われるためコバルトフエライト
の新生核が生じたりすることもなくコバルトを均
一に含む酸化鉄層が良好に形成される。さらに高
保磁力を得るため多量のコバルト塩および第一鉄
塩を使用する場合にはコバルト塩および第一鉄塩
の水溶液を２回以上に分けて添加すると均一な反
応が行えてコバルトを均一に含む酸化鉄層が良好
に形成され保磁力分布の非常に良好なコバルト含
有酸化鉄磁性粉末が得られる。
このようにして得られるコバルト含有酸化鉄磁
性粉末のコバルト含有量は、磁気記録媒体用とし
て好適な保磁力を得るため、1.5重量％以上であ
ることが好ましく、従つてコバルト塩および第一
鉄塩の水溶液を２回以上に分けて添加することに
よつて、１回ごとのコバルト添加量が0.5〜1.5重
量％の範囲内となるように調製して添加するのが
好ましい。
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。
またアルカリとしては、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。
以上のように、まず、アルカリ水溶液中に酸化
鉄磁性粉末を分散させ、次にこの分散液中にコバ
ルト塩および第一鉄塩の水溶液を２回以上に分け
て添加して反応させると、コバルトを均一に含む
酸化鉄層が酸化鉄磁性粉末の粒子表面に良好に形
成されて保磁力分布の良好なコバルト含有酸化鉄
磁性粉末が得られ、この磁性粉末を用いて得られ
る磁気記録媒体は消去特性に優れ、出力も向上す
る。
次に、この発明の実施例について説明する。
実施例 １
3000ｇの苛性ソーダを溶解させた20の水溶液
中に、長軸径0.25μ、軸比８、BET法による比表
面積33.2m2／ｇの針状γ−Fe2O3粉末3000ｇを分
散させ、これに５の水に溶解させた硫酸コバル
ト215ｇと硫酸第一鉄750ｇとを加えて45℃の温度
で４時間撹拌して反応させた。その後、５の水
に溶解させた硫酸コバルト215ｇと硫酸第一鉄750
ｇとを加え、45℃の温度でさらに６時間撹拌して
反応させた。反応終了後、水洗、脱水、乾燥して
コバルトを含む酸化鉄層を粒子表面に形成させた
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670エルステ
ツドで飽和磁化量は76.3m2／ｇであつた。またコ
バルト含有量は2.57重量％であつた。
実施例 ２
3000ｇの苛性ソーダを溶解させた、20の水溶
液中に、実施例１で使用したのと同じγ−Fe2O3
粉末3000ｇを分散させ、これに硫酸コバルト430
ｇと硫酸第一鉄1500ｇとを溶解させた10の水溶
液を２づつ、1.5時間おきに添加しながら撹拌
し、添加終了後45℃の温度でさらに４時間撹拌を
続けて反応させた。反応終了後、水洗、脱水、乾
燥してコバルトを含む酸化鉄層を粒子表面に形成
させた磁性粉末を得た。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665エ
ルステツドで、飽和磁化量は76.1emu／ｇであつ
た。またコバルト含有量は2.57重量％であつた。
比較例 １
実施例１で使用したのと同じγ−Fe2O3粉末
3000ｇを20の水に分散させた後、これに硫酸コ
バルト430ｇと硫酸第一鉄1500ｇとを加えて溶解
させた。これに10の水に溶解させた苛性ソーダ
3000ｇを加え、45℃の温度で10時間撹拌して反応
させた。反応終了後、水洗、脱水、乾燥して磁性
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660エルステツド
で、飽和磁化量は76.4emu／ｇであつた。またコ
バルト含有量は2.57重量％であつた。
次に、上記実施例１、２および比較例１で得ら
れたコバルト含有酸化鉄磁性粉末を用いて、下記
配合組成により磁性塗料を調製し、この塗料を
12μ厚のポリエステルベースフイルム上に乾燥厚
が5.5μとなるように塗布、乾燥して磁気テープを
つくつた。
コバルト含有酸化鉄磁性粉末 100重量部
VAGH（U.C.C社製、塩化ビニル−酢酸ビニル−
ビニルアルコール共重合体） 13.7 〃
タケラツクＥ−551（武田薬品工業社製、ウレタン
プレポリマー） 8.7 〃
コロネートＬ（日本ポリウレタン工業社製、三官
能性低分子量イソシアネート化合物） 2.5 〃
弁 柄 2.0 〃
パルミチン酸 0.8 〃
メチルイソブチルケトン 64 〃
トルエン 64〃
このようにして得られた各磁気テープについ
て、保磁力、消去特性および12.5KHzでの出力を
調べた。
下表はその結果である。
The present invention relates to a method for producing cobalt-containing iron oxide magnetic powder having an excellent coercive force distribution and suitable as a recording element of a magnetic recording medium. Iron oxide magnetic powder containing cobalt has a higher coercive force than iron oxide magnetic powder commonly used as a recording element in conventional magnetic recording media, and is therefore useful as a recording element in high-performance magnetic recording media. Various methods for producing such cobalt-containing iron oxide magnetic powder have been proposed, and one typical method involves dispersing iron oxide magnetic powder in an aqueous solution containing a cobalt salt and a ferrous salt. There is a method in which an aqueous alkaline solution is added to this to form an iron oxide layer containing cobalt on the surface of the iron oxide magnetic powder particles. Another method is to disperse iron oxide magnetic powder in an alkaline aqueous solution, and add an aqueous solution containing cobalt salt and ferrous salt to this to form an iron oxide layer containing cobalt on the particle surface of the iron oxide magnetic powder. There is something to be formed. However, in this conventional method, iron oxide magnetic powder is first dispersed in an aqueous solution in which cobalt salts and ferrous salts are dissolved, and then an alkaline aqueous solution is added and reacted, so the reaction solution is acidic. New nuclei of cobalt ferrite may be generated due to dissolved oxygen when transitioning from an alkaline side to an alkaline side.Also, even if iron oxide magnetic powder is dispersed in an alkaline aqueous solution and cobalt salts and ferrous salts are added to it, Even when adding an aqueous solution containing cobalt, if you try to obtain a cobalt-containing iron oxide magnetic powder with a high coercive force by using a large amount of cobalt salt and ferrous salt, the reaction will become non-uniform and the cobalt will be uniformly contained. The iron oxide layer is not formed, and the cobalt-containing iron oxide magnetic powder obtained as a result has a poor coercive force distribution, and the magnetic recording medium obtained using this magnetic powder has poor erasing characteristics and cannot obtain sufficient output. The problem was that there was no. As a result of extensive research in view of the current situation, the inventors first dispersed iron oxide magnetic powder in an alkaline aqueous solution, and then added an aqueous solution of cobalt salt and ferrous salt to this dispersion twice or more. If the aqueous solutions of cobalt salts and ferrous salts are added at least twice, the reaction will be alkaline from the beginning and new nuclei of cobalt ferrite will not be generated. By performing the reaction in separate parts, the reaction can be carried out uniformly and a cobalt-containing iron oxide magnetic powder with a very good coercive force distribution can be obtained.
It was discovered that all the drawbacks of the conventional method were solved, and this invention was made. In this invention, the iron oxide magnetic powder used as a starting material is obtained by partially reducing acicular, for example, γ-Fe 2 O 3 powder, Fe 3 O 4 powder, and γ-Fe 2 O 3 in a hydrogen stream. γ−Fe 2 O 3 obtained by
Iron oxide magnetic powder having an oxidation state intermediate to that of Fe 3 O 4 is preferably used. These iron oxide magnetic powders are first dispersed in an alkaline aqueous solution,
Next, it is preferable to add an aqueous solution of a cobalt salt and a ferrous salt to this dispersion and cause the reaction to occur.If the dispersion is first dispersed in an alkaline aqueous solution, the reaction is carried out on the alkaline side from beginning to end, resulting in the formation of new nuclei of cobalt ferrite. An iron oxide layer uniformly containing cobalt can be formed well without any smearing. Furthermore, when using a large amount of cobalt salt and ferrous salt to obtain a high coercive force, adding the aqueous solution of cobalt salt and ferrous salt in two or more portions will allow a uniform reaction to occur and contain cobalt uniformly. A cobalt-containing iron oxide magnetic powder with a well-formed iron oxide layer and a very good coercive force distribution can be obtained. The cobalt content of the cobalt-containing iron oxide magnetic powder thus obtained is preferably 1.5% by weight or more in order to obtain a coercive force suitable for use in magnetic recording media. It is preferable to add the aqueous solution in two or more portions so that the amount of cobalt added each time is within the range of 0.5 to 1.5% by weight. Suitable cobalt salts include cobalt chloride, cobalt sulfate, cobalt nitrate, etc., and ferrous salts include ferrous chloride, ferrous sulfate,
Ferrous nitrate and the like are preferably used. Further, caustic soda is usually used as the alkali, and its suitable amount is preferably at least equivalent to the total amount of cobalt salt and ferrous salt. As described above, first, iron oxide magnetic powder is dispersed in an alkaline aqueous solution, and then an aqueous solution of cobalt salt and ferrous salt is added to this dispersion in two or more portions and reacted. A cobalt-containing iron oxide magnetic powder with a good coercive force distribution is obtained by forming an iron oxide layer uniformly on the particle surface of the iron oxide magnetic powder, and a magnetic recording medium obtained using this magnetic powder can be erased. Excellent characteristics and improved output. Next, embodiments of the invention will be described. Example 1 3000 g of acicular γ-Fe 2 O 3 powder with a major axis diameter of 0.25 μ, an axial ratio of 8, and a specific surface area of 33.2 m 2 /g by BET method was dispersed in an aqueous solution containing 3000 g of caustic soda. To this were added 215 g of cobalt sulfate and 750 g of ferrous sulfate dissolved in water from Step 5, and the mixture was stirred at 45° C. for 4 hours to react. After that, 215 g of cobalt sulfate and 750 g of ferrous sulfate dissolved in water from step 5.
g was added thereto, and the mixture was further stirred at a temperature of 45° C. for 6 hours to react. After the reaction was completed, the particles were washed with water, dehydrated, and dried to obtain magnetic powder in which an iron oxide layer containing cobalt was formed on the particle surface. The cobalt-containing iron oxide magnetic powder thus obtained had a coercive force of 670 Oersted and a saturation magnetization of 76.3 m 2 /g. Moreover, the cobalt content was 2.57% by weight. Example 2 The same γ-Fe 2 O 3 as used in Example 1 was added in an aqueous solution of 20 in which 3000 g of caustic soda was dissolved.
Disperse 3000g of powder and add 430g of cobalt sulfate to this.
An aqueous solution of 10 in which g and 1500 g of ferrous sulfate were dissolved was added in two portions every 1.5 hours while stirring, and after the addition was completed, stirring was continued for an additional 4 hours at a temperature of 45° C. to cause reaction. After the reaction was completed, the particles were washed with water, dehydrated, and dried to obtain magnetic powder in which an iron oxide layer containing cobalt was formed on the particle surface. The cobalt-containing iron oxide magnetic powder thus obtained had a coercive force of 665 oersted and a saturation magnetization of 76.1 emu/g. Moreover, the cobalt content was 2.57% by weight. Comparative Example 1 Same γ-Fe 2 O 3 powder used in Example 1
After dispersing 3,000 g in 20 g of water, 430 g of cobalt sulfate and 1,500 g of ferrous sulfate were added and dissolved. Caustic soda dissolved in water for 10 minutes
3000g was added and stirred at a temperature of 45°C for 10 hours to react. After the reaction was completed, the mixture was washed with water, dehydrated, and dried to obtain a magnetic powder. The cobalt-containing iron oxide magnetic powder thus obtained had a coercive force of 660 oersted and a saturation magnetization of 76.4 emu/g. Moreover, the cobalt content was 2.57% by weight. Next, using the cobalt-containing iron oxide magnetic powders obtained in Examples 1 and 2 and Comparative Example 1, a magnetic paint was prepared according to the composition shown below.
It was coated on a 12μ thick polyester base film to a dry thickness of 5.5μ and dried to produce a magnetic tape. Cobalt-containing iron oxide magnetic powder 100 parts by weight VAGH (manufactured by UCC, vinyl chloride-vinyl acetate-
(Vinyl alcohol copolymer) 13.7 〃 Takerac E-551 (manufactured by Takeda Pharmaceutical Co., Ltd., urethane prepolymer) 8.7 〃 Coronate L (manufactured by Nippon Polyurethane Industries, Ltd., trifunctional low molecular weight isocyanate compound) 2.5 〃 Valve handle 2.0 〃 Palmitic acid 0.8 〃 Methyl isobutyl ketone 64 〃 Toluene 64〃 The coercive force, erasing characteristics, and output at 12.5 KHz of each magnetic tape thus obtained were examined. The table below shows the results.
【表】
上表から明らかなように、この発明で得られた
コバルト含有酸化鉄磁性粉末を使用して得られた
磁気テープ（実施例１および２）は、従来の方法
で得られたコバルト含有酸化鉄磁性粉末を使用し
て得られた磁気テープ（比較例１）に比し、消去
特性がよくて出力も高く、このことから、この発
明の方法で得られる磁性粉末は保磁力分布が良好
で、この磁性粉末を使用して得られる磁気記録媒
体は消去特性に優れ、良好な出力が得られること
がわかる。[Table] As is clear from the above table, the magnetic tapes obtained using the cobalt-containing iron oxide magnetic powder obtained by the present invention (Examples 1 and 2) are different from the cobalt-containing iron oxide magnetic powder obtained by the conventional method. Compared to the magnetic tape obtained using iron oxide magnetic powder (Comparative Example 1), the erasing properties are better and the output is higher. Therefore, the magnetic powder obtained by the method of this invention has a good coercive force distribution. It can be seen that the magnetic recording medium obtained using this magnetic powder has excellent erasing characteristics and can provide good output.
Claims (1)
塩とアルカリとを含む水溶液中で処理して酸化鉄
磁性粉末の粒子表面にコバルトを含む酸化鉄層を
形成するに当たり、まずアルカリ水溶液中に酸化
鉄磁性粉末を分散させ、次いで、この分散液中に
コバルト塩および第一鉄塩の水溶液を、少なくと
も２回以上に分けて添加し、酸化鉄磁性粉末の粒
子表面にコバルトを含む酸化鉄層を形成すること
を特徴とする磁性粉末の製造方法。 ２ コバルト塩水溶液を、その一回ごとの添加量
で、生成される磁性粉末中のコバルト含有量が
0.5〜２重量％の範囲内となるように、酸化鉄磁
性粉末のアルカリ分散液中に添加する特許請求の
範囲第１項記載の磁性粉末の製造方法。[Claims] 1. In forming an iron oxide layer containing cobalt on the particle surface of the iron oxide magnetic powder by treating the iron oxide magnetic powder in an aqueous solution containing a cobalt salt, a ferrous salt, and an alkali, First, iron oxide magnetic powder is dispersed in an alkaline aqueous solution, and then an aqueous solution of cobalt salt and ferrous salt is added to this dispersion in at least two portions to coat the particle surface of the iron oxide magnetic powder. A method for producing magnetic powder, the method comprising forming an iron oxide layer containing. 2 The amount of cobalt salt aqueous solution added each time increases the cobalt content in the magnetic powder produced.
2. The method for producing magnetic powder according to claim 1, wherein the iron oxide magnetic powder is added to an alkaline dispersion in an amount within the range of 0.5 to 2% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58026040A JPS59151402A (en) | 1983-02-17 | 1983-02-17 | Manufacture of magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58026040A JPS59151402A (en) | 1983-02-17 | 1983-02-17 | Manufacture of magnetic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59151402A JPS59151402A (en) | 1984-08-29 |
| JPH0516163B2 true JPH0516163B2 (en) | 1993-03-03 |
Family
ID=12182583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58026040A Granted JPS59151402A (en) | 1983-02-17 | 1983-02-17 | Manufacture of magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59151402A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS525494A (en) * | 1975-07-02 | 1977-01-17 | Fuji Photo Film Co Ltd | Ferromagnetic grit manufacturing process |
| JPS57138110A (en) * | 1981-02-19 | 1982-08-26 | Sony Corp | Ferromagnetic powder |
| JPS58115030A (en) * | 1981-12-25 | 1983-07-08 | Ishihara Sangyo Kaisha Ltd | Preparation of magnetic iron oxide powder containing cobalt |
-
1983
- 1983-02-17 JP JP58026040A patent/JPS59151402A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS525494A (en) * | 1975-07-02 | 1977-01-17 | Fuji Photo Film Co Ltd | Ferromagnetic grit manufacturing process |
| JPS57138110A (en) * | 1981-02-19 | 1982-08-26 | Sony Corp | Ferromagnetic powder |
| JPS58115030A (en) * | 1981-12-25 | 1983-07-08 | Ishihara Sangyo Kaisha Ltd | Preparation of magnetic iron oxide powder containing cobalt |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59151402A (en) | 1984-08-29 |
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