JPS6349722B2 - - Google Patents
Info
- Publication number
- JPS6349722B2 JPS6349722B2 JP55137418A JP13741880A JPS6349722B2 JP S6349722 B2 JPS6349722 B2 JP S6349722B2 JP 55137418 A JP55137418 A JP 55137418A JP 13741880 A JP13741880 A JP 13741880A JP S6349722 B2 JPS6349722 B2 JP S6349722B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- sho
- tokuko
- iron oxyhydroxide
- feooh
- 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
Links
- 239000002184 metal Substances 0.000 claims description 25
- 229910052751 metal Inorganic materials 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 23
- CUPCBVUMRUSXIU-UHFFFAOYSA-N [Fe].OOO Chemical compound [Fe].OOO CUPCBVUMRUSXIU-UHFFFAOYSA-N 0.000 claims description 11
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 claims description 11
- 239000006247 magnetic powder Substances 0.000 claims description 11
- 235000019353 potassium silicate Nutrition 0.000 claims description 10
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 239000001257 hydrogen Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 238000010304 firing Methods 0.000 claims description 4
- 229910006540 α-FeOOH Inorganic materials 0.000 claims description 3
- 229910006299 γ-FeOOH Inorganic materials 0.000 claims description 2
- 229910002588 FeOOH Inorganic materials 0.000 claims 1
- 230000005291 magnetic effect Effects 0.000 description 26
- 230000005294 ferromagnetic effect Effects 0.000 description 12
- 239000000843 powder Substances 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 150000002739 metals Chemical class 0.000 description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 6
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 5
- 229910052753 mercury Inorganic materials 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 5
- 230000004907 flux Effects 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 150000003377 silicon compounds Chemical class 0.000 description 3
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- -1 organic acid salts Chemical class 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 description 1
- 229910017061 Fe Co Inorganic materials 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 150000001728 carbonyl compounds Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 229910052598 goethite Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000003891 oxalate salts Chemical class 0.000 description 1
- 125000005498 phthalate group Chemical class 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 229910001379 sodium hypophosphite Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 229910003153 β-FeOOH Inorganic materials 0.000 description 1
Landscapes
- Paints Or Removers (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Magnetic Record Carriers (AREA)
- Hard Magnetic Materials (AREA)
Description
本発明は強磁性粉末の製造法に関するものであ
り、特に高密度記録に適した保持力及び飽和磁束
密度の高い磁気記録媒体用の強磁性金属、合金粉
末の製造方法に関するものである。
従来、磁気記録体に使用されていた強磁性粉末
としてはγ−Fe2O3、Co含有γ−Fe2O3、Fe3O4
Co含有Fe3O4、Fe3O4−γ−Fe2O3、CrO2等があ
つた。しかしこれらの強磁性粉末は今後の磁性層
の単位体積当りの記録信号を多くしようとする高
密度化の方向に適したものであるとは言えない。
すなわち高密度記録に使用するには保磁力（Hc）
および磁束密度（σ）等の磁気特性が不充分であ
り記録波長の短い信号の磁気記録にはあまり適し
ていない。
そのため最近になり高密度記録に適する強磁性
媒体の開発が盛んになされている。その対象とな
る材料の１つとして強磁性金属、合金の粉末があ
る。すなわち、γ−Fe2O3は単位体積当りの飽和
磁束密度は約5000ガウスであるが、Fe、Fe−Co
合金等ではγ−Fe2O3の約４倍に当る約20000〜
25000ガウスにも及ぶ高い飽和磁束密度を有して
いると言われ、きわめて簡単に換算すれば約４倍
の再生出力が期待され、より高密度記録が可能と
なる。
このような強磁性金属、合金粉末の製造法とし
ては従来から次のような方法が検討されてきた。
(1) 強磁性の金属、合金の有機酸塩（主として蓚
酸塩）を加熱分解し、還元性気体で還元する方
法。
例えば特公昭36−11412、特公昭36−22230、
特公昭40−8027、特公昭42−24032、特公昭43
−22394、特公昭47−38417、特開昭47−38523
号、特公昭48−29280、特開昭48−22346、特開
昭48−22994、米国特許第3186829、米国特許第
3190748号、フタル酸塩を用いるものとして特
公昭47−4286、
(2) オキシ水酸化鉄あるいはこれらに他の金属
（例えばCo）を含有（ドープ）せしめたもの、
あるいは酸化鉄、又はフエライト組成酸化物を
還元性気体で還元する方法。
例えば特公昭35−3862、特公昭37−11520、
特公昭39−20939、特公昭47−29706、特公昭47
−30477、特公昭47−39477、特開昭46−5057、
特開昭46−7153、特公昭48−24952、特開昭48
−79153、特開昭48−82393、特公昭49−7313、
特開昭49−135867、特公昭51−5608、米国特許
第3598568、米国特許第3607220、米国特許第
3702270、英国特許第640438、
(3) 強磁性金属、合金を不活性ガス中で蒸発させ
る方法。例えば、特公昭47−27718、特公昭48
−964、特公昭48−42780、特開昭48−25662〜
25665、特開昭48−31166、特開昭48−55400、
特開昭48−81092、特開昭49−52134、
(4) 金属カルボニル化合物を分解する方法。
例えば、特公昭45−16868、米国特許第
2983997、米国特許第3172776、米国特許第
3200007、米国特許第3228882、
(5) 水銀電解によつて強磁性金属粉末を電析させ
たのち、水銀を分解除去する方法。
例えば、特公昭39−15525、特公昭40−8123、
特公昭47−6007、米国特許第3156650、米国特
許第3262812、
(6) 強磁性を有する金属の塩を、その溶液中で次
亜リン酸ナトリウム、あるいは水素化ホウ素ナ
トリウム、などで湿式還元する方法。
例えば、特公昭38−20520、特公昭38−
26555、特公昭43−20116、特公昭45−9869、特
公昭47−7820、特公昭47−16052、特公昭47−
41718、特公昭47−41719、特開昭47−1353、特
開昭47−42252、特開昭47−42253、特開昭48−
7585、特開昭48−25896、特開昭48−44194、特
開昭48−79754、特開昭48−82396、特開昭48−
28999、特開昭48−1998、米国特許第3607218、
米国特許第3494760、米国特許第3535104、米国
特許第3661556、米国特許第3663318、米国特許
第3669643、米国特許第3672867、
(7) その他、例えば衝撃大電流を通じて放電爆発
によつて強磁性金属粉末を生成させる方法。
例えば特開昭47−33857、
以上のように、各種方法によつて検討されて来
たが、それぞれ、どの方法も一長一短を有してお
り、まだ、いずれも工業的、実用的な意味におい
て、決定的な方法とはなり得ない。
例えば(1)の蓚酸塩の分解による方法は古くから
検討された来た方法であるが、この方法で得られ
る磁性粉末は一般に粒子サイズが大きく５〜10μ
程度もあり、このままでは磁気テープとした時テ
ープの表面がザラザラして、雑音レベルが悪く、
また、磁気ヘツドの摩耗、およびヘツドとテープ
表面の密着性がさまたげられ、目的とする高密度
化記録が実現しがたいという欠点がある。
また(3)の蒸発法は複雑な装置および作業を必要
とし、大規模な実施は、工業性、経済性の面で欠
点を有している。
また(5)の水銀電解法においては、電着した生成
物は４〜６％の水銀を含んだ樹枝状の粒子であ
り、これを熱処理して樹枝状粒子から除くわけで
あるが、水銀の完全な除去は困難であり、水銀公
害等の面からも実用化にはむづかしい問題点を有
している。
また(6)の湿式還元反応による方法については、
この方法で得られた強磁性金属、合金粉末は表面
の活性度が強いため自然性が強く、空気中の酸素
や湿気に弱く、常温、常湿においても、徐々に酸
化され、磁気特性の低下をまねきやすい。またこ
の方法で得られる個々の粒子は糸状をしている
が、結合剤と混合分散処理の過程において、その
粒子形状の破壊を生じて磁場配向性が悪くなり、
磁気記録体の磁気特性、特に角形比が悪くなる欠
点を有している。
さて本発明は(2)のオキシ水酸化鉄、又は酸化鉄
を還元性ガスで乾式還元する方法に属するもので
あるが、これに属する従来の方法についても幾つ
かの欠点が指摘されていた。まず、還元処理が通
常高温水素気流中で行なわれるため、体積の減
少、多孔質化、形状の変化、焼結が生じて、たと
え望ましい形状の鉄酸化物から出発しても期待ほ
どの磁気特性が得られ難い。
これはγ−Fe2O3の通常の製造工程においても
α−Fe2O3→Fe3O4の工程つまり水素ガスによつ
てα−Fe2O3の1/9の酸素を取る工程において、
形状の変化、焼結が一番起り易いと言われ、これ
を防ぐ努力がかなりなされている。これに比較し
て金属、合金の場合はさらに全部の酸素を取るわ
けであるから、なおさら、形状の変化、焼結は激
しくなる方向にあると言え、保磁力（Hc）、角形
比が悪く、テープ化において分散が不完全となり
記録材料的に、有望な性質をそなえているにもか
かわらず実用的になり得ていない。また、この方
法で得られた金属、合金粉末も発火性であるとい
う欠点を有し、実際上の使用の妨げとなつてい
る。
本発明は上記欠点を解除するものである。
すなわち、針状オキシ水酸化鉄を水ガラスで処
理した後、過、水洗、焼成し次いで還元するこ
とにより、上記欠点である形状の崩れ、焼結が防
止され、保持力（Hc）、角形比（σr／σs）、分散
性に優れ、かつ発火性のおさえられた安定な磁気
記録用強磁性体として充分使用に耐え得る金属粉
末が得られる。
本発明に用いられる針状オキシ水酸化鉄として
はα−FeOOH、β−FeOOH及びγ−FeOOHが
挙げられ、またこれらの混合物であつても良い。
本発明でいう針状オキシ水酸化鉄とは上記針状オ
キシ水酸化鉄にCo、Ni、Ti、Bi、Mo、Agなど
の金属をドープせしめたものも含まれる。
ケイ素化合物による処理は上記原料を水に懸濁
させた後、ケイ素化合物を溶解させ、良く撹拌、
混合することにより行なわれる。処理に用いられ
るケイ素化合物としては水に可溶性のものもしく
はコロイド状のものであればよく、例えば
Na2SiO3、Na2Si2O5等の如きコイ酸塩、Si
（OH）4、コロイドシリカ等を挙げることができ
るが、特に水ガラスが好適である。
また、水ガラスによる処理量は原料の針状オキ
シ水酸化鉄に対してFe2O3換算で0.1〜10重量％で
ある。この水ガラスの使用量については多くなる
と金属、合金粉の磁気特性が稀釈されることにな
り、特性値を落すから多量の使用は望ましくな
い。
次いで処理物をフイルター等で過し、水洗す
る。
次いでこれら処理、過、水洗がなされた針状
オキシ水酸化鉄を600〜800℃で焼成し、しかる
後、600℃を越えない温度、好ましくは500℃を越
えない温度で水素雰囲気中において還元する。濃
度については下限は実際上ないが、低温において
は反応が非常にゆつくり進むので、実施の観点か
らは、反応時間が長くなつて実際的でなくなるの
をさけるため、少なくとも250℃の温度を使用す
べきである。しかし、200℃程度の低い温度でも
可能である。
還元後、還元器を冷却して、空気１％および窒
素99％の混合ガスを還元器に導入し、約30分の間
隔で、このガスの空気含有量を２倍づつにする。
４〜５時間後、空気だけに切り替え、還元器から
磁性鉄粉を取り出すことができる。そして、磁気
テープ、その他の磁気記録体とすることができ
る。
つぎに、さらに詳細に、本発明の具体化例を実
施例をもつて説明するが、この実施例によつて本
発明の制限がなされるものではない。
実施例１、比較例１
針状晶ゲータイト（α−FeOOH）100ｇを９
の水に懸濁させJIS−１号水ガラス９ｇ（α−
Fe2O3換算で10重量％）を溶解し、40分間撹拌し
た後、過し、充分に水洗した。ケーキは乾燥し
た後400、500、600、700、800℃の各温度で焼成
した後、水素ガスで還元した。
得られた金属磁性粉の磁気特性を表−１に示し
た。尚焼成しない場合をも比較例に併記した。
尚、焼成は空気雰囲気中で２時間行い、還元は次
の条件により行つた。すなわち、窒素気流中で
450℃まで約１時間かけて昇温させ、次いで窒素
を水素に切換え、水素流量を２／minとし、３
時間、450℃に維持した。還元後、窒素気流中で
冷却し、次いで空気１％および窒素99％の混合ガ
スを導入し、約30分の間隔で、このガスの空気含
有量を２倍づつにし、４時間後に空気だけに切り
換えた。
The present invention relates to a method for producing ferromagnetic powder, and in particular to a method for producing ferromagnetic metal or alloy powder for magnetic recording media with high coercive force and high saturation magnetic flux density suitable for high-density recording. Ferromagnetic powders conventionally used in magnetic recording materials include γ-Fe 2 O 3 , Co-containing γ-Fe 2 O 3 , Fe 3 O 4
Co-containing Fe 3 O 4 , Fe 3 O 4 −γ−Fe 2 O 3 , CrO 2 , etc. were found. However, these ferromagnetic powders cannot be said to be suitable for the future trend toward higher densification in which the recording signal per unit volume of the magnetic layer is increased.
In other words, coercive force (Hc) is required for use in high-density recording.
Also, the magnetic properties such as magnetic flux density (σ) are insufficient, and it is not very suitable for magnetic recording of signals with short recording wavelengths. Therefore, recently, ferromagnetic media suitable for high-density recording have been actively developed. One of the target materials is powder of ferromagnetic metals and alloys. In other words, the saturation magnetic flux density per unit volume of γ-Fe 2 O 3 is approximately 5000 Gauss, but that of Fe, Fe-Co
For alloys, etc., it is about 20,000~, which is about four times that of γ-Fe 2 O 3 .
It is said to have a saturation magnetic flux density as high as 25,000 gauss, and in very simple terms, it is expected that the playback output will be about four times as high, making even higher density recording possible. Conventionally, the following methods have been studied as methods for producing such ferromagnetic metal and alloy powders. (1) A method in which organic acid salts (mainly oxalates) of ferromagnetic metals and alloys are thermally decomposed and reduced with a reducing gas. For example, Tokuko Sho 36-11412, Tokko Sho 36-22230,
Tokuko Sho 40-8027, Tokuko Sho 42-24032, Tokko Shou 43
−22394, JP 1977-38417, JP 47-38523
No. 48-29280, 22346-2013, 22994-1984, U.S. Patent No. 3186829, U.S. Patent No.
No. 3190748, Japanese Patent Publication No. 47-4286 for using phthalates, (2) Iron oxyhydroxide or these doped with other metals (e.g. Co),
Alternatively, a method of reducing iron oxide or ferrite composition oxide with a reducing gas. For example, Tokuko Sho 35-3862, Tokko Sho 37-11520,
Tokuko Sho 39-20939, Tokuko Sho 47-29706, Tokuko Sho 47
−30477, Japanese Patent Publication No. 47-39477, Japanese Patent Publication No. 46-5057,
Japanese Patent Publication No. 1973-7153, Special Publication No. 48-24952, Japanese Patent Publication No. 1977-24952
-79153, Japanese Patent Publication No. 1983-82393, Special Publication No. 49-7313,
JP 49-135867, JP 51-5608, U.S. Patent No. 3598568, U.S. Patent No. 3607220, U.S. Patent No.
3702270, British Patent No. 640438, (3) Method for vaporizing ferromagnetic metals and alloys in an inert gas. For example, Tokuko Sho 47-27718, Tokuko Sho 48
-964, JP 1977-42780, JP 1977-25662~
25665, Japanese Patent Publication No. 48-31166, Japanese Patent Publication No. 48-55400,
JP-A-48-81092, JP-A-49-52134, (4) Method for decomposing metal carbonyl compounds. For example, Japanese Patent Publication No. 45-16868, U.S. Patent No.
2983997, U.S. Patent No. 3172776, U.S. Patent No.
3200007, US Patent No. 3228882, (5) A method of electrodepositing ferromagnetic metal powder by mercury electrolysis and then decomposing and removing mercury. For example, Tokuko Sho 39-15525, Tokuko Sho 40-8123,
Japanese Patent Publication No. 47-6007, U.S. Patent No. 3156650, U.S. Patent No. 3262812, (6) A method of wet reduction of a ferromagnetic metal salt with sodium hypophosphite, sodium borohydride, etc. in its solution. . For example, Tokuko Sho 38-20520, Tokuko Sho 38-
26555, Special Publication No. 43-20116, Special Publication No. 45-9869, Special Publication No. 47-7820, Special Publication No. 47-16052, Special Publication No. 47-
41718, JP 47-41719, JP 47-1353, JP 47-42252, JP 47-42253, JP 48-
7585, JP-A 1987-25896, JP-A 48-44194, JP-A 48-79754, JP-A 1972-82396, JP-A 1972-
28999, Japanese Unexamined Patent Publication No. 48-1998, US Patent No. 3607218,
U.S. Patent No. 3494760, U.S. Patent No. 3535104, U.S. Patent No. 3661556, U.S. Patent No. 3663318, U.S. Patent No. 3669643, U.S. Patent No. 3672867; How to generate it. For example, Japanese Patent Application Laid-Open No. 47-33857. As mentioned above, various methods have been investigated, but each method has its own advantages and disadvantages, and none of them has yet been applied in an industrial or practical sense. It cannot be a definitive method. For example, method (1) by decomposing oxalate is a method that has been studied for a long time, but the magnetic powder obtained by this method generally has a large particle size of 5 to 10 μm.
To some extent, if left as is, when used as a magnetic tape, the surface of the tape would be rough and the noise level would be poor.
Another disadvantage is that the magnetic head is worn out and the adhesion between the head and the tape surface is hindered, making it difficult to achieve the desired high-density recording. Furthermore, the evaporation method (3) requires complicated equipment and operations, and its large-scale implementation has disadvantages in terms of industrial efficiency and economy. In addition, in the mercury electrolysis method (5), the electrodeposited product is dendritic particles containing 4 to 6% mercury, which is removed from the dendritic particles by heat treatment. It is difficult to completely remove it, and there are also problems such as mercury pollution that make it difficult to put it into practical use. Regarding the method using wet reduction reaction (6),
The ferromagnetic metals and alloy powders obtained by this method have a strong surface activity, making them highly natural, and are sensitive to oxygen and moisture in the air. Even at room temperature and humidity, they gradually oxidize and deteriorate their magnetic properties. easy to imitate. In addition, the individual particles obtained by this method are thread-like, but during the process of mixing and dispersing with the binder, the particle shape is destroyed and the magnetic field orientation becomes poor.
This has the disadvantage that the magnetic properties of the magnetic recording medium, especially the squareness ratio, deteriorate. Now, the present invention belongs to the method (2) of dry reducing iron oxyhydroxide or iron oxide with a reducing gas, but some drawbacks have been pointed out in the conventional methods related thereto. First, the reduction process is usually carried out in a high-temperature hydrogen stream, which results in volume reduction, porosity, shape changes, and sintering, resulting in less-than-expected magnetic properties even if starting from iron oxide in the desired shape. is difficult to obtain. This is true even in the normal manufacturing process of γ-Fe 2 O 3 , in the process of α-Fe 2 O 3 → Fe 3 O 4 , that is, the process of removing 1/9 of the oxygen from α-Fe 2 O 3 with hydrogen gas. ,
It is said that shape change and sintering are the most likely to occur, and considerable efforts are being made to prevent this. In comparison, in the case of metals and alloys, all the oxygen is removed, so it can be said that shape changes and sintering become even more severe, resulting in poor coercive force (Hc) and squareness ratio. Due to incomplete dispersion during tape production, it has not been practical as a recording material, although it has promising properties. Furthermore, the metal and alloy powders obtained by this method also have the disadvantage of being flammable, which hinders their practical use. The present invention eliminates the above drawbacks. In other words, by treating acicular iron oxyhydroxide with water glass, filtering, washing with water, firing, and then reducing, the above-mentioned drawbacks of shape collapse and sintering can be prevented, and the holding force (Hc) and squareness ratio can be improved. (σr/σs), a metal powder with excellent dispersibility and suppressed ignitability that can be used as a stable ferromagnetic material for magnetic recording is obtained. The acicular iron oxyhydroxide used in the present invention includes α-FeOOH, β-FeOOH and γ-FeOOH, and may also be a mixture thereof.
The acicular iron oxyhydroxide used in the present invention includes the above-mentioned acicular iron oxyhydroxide doped with metals such as Co, Ni, Ti, Bi, Mo, and Ag. Treatment with a silicon compound involves suspending the above raw materials in water, dissolving the silicon compound, stirring well,
This is done by mixing. The silicon compound used in the treatment may be water-soluble or colloidal; for example,
Coiates such as Na 2 SiO 3 , Na 2 Si 2 O 5 etc., Si
Examples include (OH) 4 , colloidal silica, and water glass is particularly suitable. The amount of water glass treated is 0.1 to 10% by weight in terms of Fe 2 O 3 based on the raw material acicular iron oxyhydroxide. It is undesirable to use a large amount of water glass, as the magnetic properties of the metal or alloy powder will be diluted and the characteristic values will be lowered. Next, the treated product is filtered and washed with water. The acicular iron oxyhydroxide that has been subjected to these treatments, filtering, and water washing is then calcined at 600 to 800°C, and then reduced in a hydrogen atmosphere at a temperature not exceeding 600°C, preferably not exceeding 500°C. . There is practically no lower limit for concentration, but since the reaction proceeds very slowly at low temperatures, from a practical point of view a temperature of at least 250°C should be used to avoid long reaction times that become impractical. Should. However, it is also possible at temperatures as low as 200°C. After reduction, the reducer is cooled and a gas mixture of 1% air and 99% nitrogen is introduced into the reducer, doubling the air content of this gas at approximately 30 minute intervals.
After 4-5 hours, it is possible to switch to air only and remove the magnetic iron powder from the reducer. Then, it can be a magnetic tape or other magnetic recording medium. Next, embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1, Comparative Example 1 100g of acicular goethite (α-FeOOH) was
9 g of JIS-1 water glass (α-
10% by weight (calculated as Fe 2 O 3 ) was dissolved therein, stirred for 40 minutes, filtered, and thoroughly washed with water. After drying, the cake was baked at temperatures of 400, 500, 600, 700, and 800°C, and then reduced with hydrogen gas. The magnetic properties of the obtained metal magnetic powder are shown in Table 1. In addition, the case where no firing was performed is also shown in the comparative example.
Incidentally, the calcination was performed in an air atmosphere for 2 hours, and the reduction was performed under the following conditions. That is, in a nitrogen stream
Raise the temperature to 450℃ over about 1 hour, then switch nitrogen to hydrogen, set the hydrogen flow rate to 2/min, and heat for 3 hours.
The temperature was maintained at 450°C for an hour. After reduction, it is cooled in a stream of nitrogen, then a gas mixture of 1% air and 99% nitrogen is introduced, the air content of this gas is doubled at intervals of about 30 minutes, and after 4 hours it is reduced to air only. I switched.
【表】
実施例２、比較例２
水ガラス4.5ｇ（α−Fe2O3に対し５重量％）を
用いる以外は実施例１と同様にして金属磁性粉を
得た。金属磁性粉の磁気特性を表−２に示した。[Table] Example 2, Comparative Example 2 Metal magnetic powder was obtained in the same manner as in Example 1, except that 4.5 g of water glass (5% by weight based on α-Fe 2 O 3 ) was used. The magnetic properties of the metal magnetic powder are shown in Table 2.
【表】
実施例３、比較例３
水ガラス0.9ｇ（α−Fe2O3に対し１重量％）を
用いる以外は実施例１と同様にして金属磁性粉を
得た。金属磁性粉の磁気特性を表−３に示した。
尚焼成しない場合を比較例２として併記した。[Table] Example 3, Comparative Example 3 Metal magnetic powder was obtained in the same manner as in Example 1, except that 0.9 g of water glass (1% by weight based on α-Fe 2 O 3 ) was used. The magnetic properties of the metal magnetic powder are shown in Table 3.
The case where no firing was performed was also shown as Comparative Example 2.
【表】【table】
【表】
実施例４、比較例４
水ガラス0.09ｇ（α−Fe2O3に対し0.1重量％）
を用いる以外は実施例１と同様にして金属磁性粉
を得た。金属磁性粉の磁気特性を表−４に示し
た。[Table] Example 4, Comparative Example 4 Water glass 0.09g (0.1% by weight based on α-Fe 2 O 3 )
A metal magnetic powder was obtained in the same manner as in Example 1 except that . The magnetic properties of the metal magnetic powder are shown in Table 4.
【表】
比較例 ５
水ガラス処理をしない以外は実施例４と同様に
して金属磁性粉を得た。金属磁性粉の磁気特性を
表−５に示した。[Table] Comparative Example 5 Metal magnetic powder was obtained in the same manner as in Example 4 except that the water glass treatment was not performed. The magnetic properties of the metal magnetic powder are shown in Table 5.
Claims (1)
鉄に対しFe2O3換算で0.1〜10重量％の水ガラスで
処理した後、濾過、水洗し、600〜800℃の温度で
焼成し、次いで還元することを特徴とする金属磁
性粉末の製造法。 ２ 針状オキシ水酸化鉄がα−FeOOH、β−
FeOOH及びγ−FeOOHの内１種若しくは２種
以上の混合物である特許請求の範囲第１項記載の
製造法。 ３ 還元温度が200〜600℃である特許請求の範囲
第１項記載の製造法。 ４ 還元が水素気流中で行なわれる特許請求の範
囲第１項記載の製造法。[Scope of Claims] 1. Acicular iron oxyhydroxide is treated with water glass in an amount of 0.1 to 10% by weight calculated as Fe 2 O 3 based on the acicular iron oxyhydroxide, and then filtered and washed with water. A method for producing metal magnetic powder, which is characterized by firing at a temperature of 800°C and then reducing. 2 Acicular iron oxyhydroxide is α-FeOOH, β-
The manufacturing method according to claim 1, wherein the method is one or a mixture of two or more of FeOOH and γ-FeOOH. 3. The production method according to claim 1, wherein the reduction temperature is 200 to 600°C. 4. The production method according to claim 1, wherein the reduction is carried out in a hydrogen stream.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55137418A JPS5763605A (en) | 1980-10-01 | 1980-10-01 | Manufacture of metallic magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55137418A JPS5763605A (en) | 1980-10-01 | 1980-10-01 | Manufacture of metallic magnetic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5763605A JPS5763605A (en) | 1982-04-17 |
| JPS6349722B2 true JPS6349722B2 (en) | 1988-10-05 |
Family
ID=15198160
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55137418A Granted JPS5763605A (en) | 1980-10-01 | 1980-10-01 | Manufacture of metallic magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5763605A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5980901A (en) * | 1982-11-01 | 1984-05-10 | Fuji Photo Film Co Ltd | Manufacture of ferromagnetic metal powder |
| JPS60181210A (en) * | 1984-02-27 | 1985-09-14 | Fuji Photo Film Co Ltd | Manufacture of ferromagnetic metallic powder |
| JPH02175806A (en) * | 1988-12-27 | 1990-07-09 | Ishihara Sangyo Kaisha Ltd | Manufacture of metal magnetic powder for magnetic recorder |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4883100A (en) * | 1972-01-21 | 1973-11-06 | ||
| JPS5177900A (en) * | 1974-11-29 | 1976-07-06 | Montedison Spa | |
| JPS534895A (en) * | 1976-06-16 | 1978-01-17 | Fujitsu Ltd | Manufacture of needle-shaped magnetic iron particles |
| JPS5422958A (en) * | 1977-07-20 | 1979-02-21 | Matsushita Electric Ind Co Ltd | Dust remover for vacuum cleaner |
-
1980
- 1980-10-01 JP JP55137418A patent/JPS5763605A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4883100A (en) * | 1972-01-21 | 1973-11-06 | ||
| JPS5177900A (en) * | 1974-11-29 | 1976-07-06 | Montedison Spa | |
| JPS534895A (en) * | 1976-06-16 | 1978-01-17 | Fujitsu Ltd | Manufacture of needle-shaped magnetic iron particles |
| JPS5422958A (en) * | 1977-07-20 | 1979-02-21 | Matsushita Electric Ind Co Ltd | Dust remover for vacuum cleaner |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5763605A (en) | 1982-04-17 |
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