JPH08246002A - Surface-coated mn-bi magnetic recording powder and its production - Google Patents
Surface-coated mn-bi magnetic recording powder and its productionInfo
- Publication number
- JPH08246002A JPH08246002A JP7079745A JP7974595A JPH08246002A JP H08246002 A JPH08246002 A JP H08246002A JP 7079745 A JP7079745 A JP 7079745A JP 7974595 A JP7974595 A JP 7974595A JP H08246002 A JPH08246002 A JP H08246002A
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- JP
- Japan
- Prior art keywords
- powder
- magnetic recording
- magnetic
- coated
- protective film
- 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.)
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Abstract
Description
【0001】[0001]
【産業上の利用分野】この発明は、磁気カード、磁気テ
ープ等(以下、これらを磁気記録媒体と総称する)の製
造に使用される表面被覆Mn−Bi系磁気記録粉末に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated Mn-Bi magnetic recording powder used in the manufacture of magnetic cards, magnetic tapes and the like (these are collectively referred to as magnetic recording media hereinafter).
【0002】[0002]
【従来の技術】Mn−Bi系磁性粉末を磁気記録粉末と
して用いることは知られており、このMn−Bi系磁性
粉末はBi:20〜60原子%を含有し、残りがMnお
よび不可避不純物からなる組成を有し、さらに必要に応
じてMnあるいはBiの一部をRu,Rh,Pd,A
s,Sb,Al,Ga,Ge,In,Tl,P,Sn,
Pb,Ti,Ir等で20モル%以下の置換が可能なこ
とも知られている。2. Description of the Related Art It is known to use Mn-Bi magnetic powder as a magnetic recording powder. This Mn-Bi magnetic powder contains Bi: 20 to 60 atomic%, and the rest is Mn and inevitable impurities. And a part of Mn or Bi may be added to Ru, Rh, Pd, A if necessary.
s, Sb, Al, Ga, Ge, In, Tl, P, Sn,
It is also known that substitution with Pb, Ti, Ir or the like can be performed at 20 mol% or less.
【0003】これらMn−Bi系磁性粉末は、磁気記録
粉末として優れた特性を有するが酸化しやすく、酸化に
ともなって磁気特性も低下する。そのために、Mn−B
i系磁性粉末の表面に保護皮膜を形成し(以下、この表
面に保護皮膜を形成したMn−Bi系磁性粉末を表面被
覆Mn−Bi系磁気記録粉末という)、酸化による磁気
特性の低下を防いでいる。例えば、特公昭60−571
27号公報には、Mn−Bi系磁性粉末の表面に窒素を
含有する有機化合物を保護皮膜として形成した表面被覆
Mn−Bi系磁気記録粉末が記載されている。この窒素
を含有する有機化合物保護皮膜を形成した表面被覆Mn
−Bi系磁気記録粉末は、120℃を越えた温度に長時
間さらされると窒素を含有する有機化合物が気化消失
し、耐食性が劣化する。したがって、この従来の表面被
覆Mn−Bi系磁気記録粉末で作製した磁気記録媒体は
120℃以下で使用することが好ましいとされている。These Mn-Bi magnetic powders have excellent characteristics as magnetic recording powders, but are easily oxidized, and the magnetic characteristics are deteriorated with the oxidation. Therefore, Mn-B
A protective film is formed on the surface of the i-based magnetic powder (hereinafter, the Mn-Bi-based magnetic powder having the protective film formed thereon is referred to as a surface-coated Mn-Bi-based magnetic recording powder) to prevent deterioration of magnetic properties due to oxidation. I'm out. For example, Japanese Patent Publication Sho 60-571
Japanese Unexamined Patent Publication (Kokai) No. 27 describes surface-coated Mn-Bi magnetic recording powder in which an organic compound containing nitrogen is formed as a protective film on the surface of Mn-Bi magnetic powder. This surface-coated Mn on which a protective film for organic compound containing nitrogen is formed
In the -Bi magnetic recording powder, when exposed to a temperature exceeding 120 ° C for a long time, the organic compound containing nitrogen is vaporized and disappears, and the corrosion resistance is deteriorated. Therefore, it is said that it is preferable to use a magnetic recording medium made of this conventional surface-coated Mn-Bi magnetic recording powder at 120 ° C. or lower.
【0004】[0004]
【発明が解決しようとする課題】しかし、近年、120
℃を越える高温度の過酷な状況下で使用することのでき
る磁気記録媒体が求められており、かかる高温度状況下
で使用することができる磁気記録媒体を作製するための
磁気記録粉末の開発が求められていた。However, in recent years, 120
There is a demand for a magnetic recording medium that can be used under severe conditions of high temperature exceeding ℃, and development of magnetic recording powder for producing a magnetic recording medium that can be used under such high temperature conditions has been required. It was wanted.
【0005】[0005]
【課題を解決するための手段】そこで、本発明者等は、
かかる観点から、高温に長時間さらされても磁気特性が
低下することのない表面被覆Mn−Bi系磁気記録粉末
を得るべく研究を行った結果、二酸化ケイ素(以下、S
iO2 と記す)皮膜を保護皮膜としてMn−Bi系磁性
粉末の表面に形成した表面被覆Mn−Bi系磁気記録粉
末は、高温に長時間さらされても優れた耐食性を示すと
いう知見を得たのである。Therefore, the present inventors have
From this point of view, as a result of research to obtain a surface-coated Mn-Bi magnetic recording powder that does not deteriorate in magnetic properties even when exposed to high temperatures for a long time, silicon dioxide (hereinafter referred to as S
iO 2 and referred) surface coating Mn-Bi-based magnetic recording powder formed on the surface of the Mn-Bi-based magnetic powder coatings as a protective coating, to obtain a finding that exhibits excellent corrosion resistance even when subjected to a high temperature for a long time Of.
【0006】この発明は、かかる知見に基づいてなされ
たものであって、 (1) Mn−Bi系磁性粉末表面にSiO2 保護皮膜
が形成されている表面被覆Mn−Bi系磁気記録粉末、
に特徴を有するものである。The present invention has been made on the basis of the above findings. (1) A surface-coated Mn-Bi magnetic recording powder in which a SiO 2 protective film is formed on the surface of the Mn-Bi magnetic powder,
It is characterized by
【0007】この発明の表面被覆Mn−Bi系磁気記録
粉末のSiO2 保護皮膜の厚さは0.01〜0.2μm
が好ましく、その理由はSiO2 保護皮膜が0.01μ
m未満では膜厚が薄すぎて十分な耐食性が得られず、一
方、0.2μmを越えると磁気特性が落ちるとともに、
製造時の加熱処理工程で皮膜に亀裂が入り、かえって耐
食性改善効果が減少するので好ましくないことによるも
のである。The thickness of the SiO 2 protective film of the surface-coated Mn-Bi magnetic recording powder of the present invention is 0.01 to 0.2 μm.
Is preferable because the SiO 2 protective film has a thickness of 0.01 μm.
If it is less than m, the film thickness is too thin to obtain sufficient corrosion resistance, while if it exceeds 0.2 μm, the magnetic properties deteriorate and
This is because the coating film is cracked during the heat treatment process during production, and the effect of improving corrosion resistance is reduced, which is not preferable.
【0008】SiO2 保護皮膜の一層好ましい厚さは
0.03〜0.15μmである。A more preferable thickness of the SiO 2 protective film is 0.03 to 0.15 μm.
【0009】この発明の表面被覆Mn−Bi系磁気記録
粉末のSiO2 保護皮膜は、ケイ素のアルコキシドを用
いたゾル・ゲル反応により形成するものであり、したが
ってこの発明は、 (2) Siのアルコキシドの加水分解物の皮膜をMn
−Bi系磁性粉末表面に形成させたのち、加熱処理を施
して前記加水分解物の縮合反応を起こさせてMn−Bi
系磁性粉末の表面にSiO2 保護皮膜を形成する表面被
覆Mn−Bi系磁気記録粉末の製造方法、にも特徴を有
するものである。The SiO 2 protective film of the surface-coated Mn-Bi magnetic recording powder of the present invention is formed by a sol-gel reaction using a silicon alkoxide. Therefore, the present invention provides (2) a Si alkoxide. The hydrolyzate film of Mn
After being formed on the surface of the -Bi-based magnetic powder, heat treatment is performed to cause a condensation reaction of the hydrolyzate to cause Mn-Bi.
It is also characterized by a method for producing a surface-coated Mn-Bi magnetic recording powder in which a SiO 2 protective film is formed on the surface of the magnetic magnetic powder.
【0010】Siのアルコキシドとしてはテトラエチル
オルトシリケート(以下、TEOSと記す)が好まし
く、このTEOSをアルコールに溶解したアルコール溶
液に加水分解反応の触媒として少量の酸を添加したのち
撹拌し放置すると化1に示される加水分解が起こる。Tetraethyl orthosilicate (hereinafter referred to as TEOS) is preferable as the alkoxide of Si, and a small amount of an acid as a catalyst for the hydrolysis reaction is added to an alcohol solution prepared by dissolving this TEOS in an alcohol, and the mixture is stirred and left to stand. The hydrolysis shown in 1 occurs.
【0011】[0011]
【化1】 上記加水分解反応の触媒としての酸は、硫酸、硝酸、塩
酸、シュウ酸、酢酸などいかなる酸でもよいが、特に硝
酸が好ましい。Embedded image The acid as the catalyst for the above hydrolysis reaction may be any acid such as sulfuric acid, nitric acid, hydrochloric acid, oxalic acid, acetic acid, etc., but nitric acid is particularly preferable.
【0012】この加水分解が起きた溶液をさらにアルコ
ールで希釈するがこの希釈された溶液濃度はSiO2 換
算で0.1〜5wt%となるように希釈することが好まし
い。その理由は、溶液中のSiO2 換算濃度が5wt%を
越えるとSiO2 保護皮膜の厚さが0.2μmよりも厚
くなり、一方SiO2 換算濃度が0.1wt%未満ではS
iO2 保護皮膜の厚さが0.01μm未満となることに
よるものである。The solution in which the hydrolysis has occurred is further diluted with alcohol, but it is preferable that the diluted solution has a concentration of 0.1 to 5 wt% in terms of SiO 2 . The reason is that if the SiO 2 conversion concentration in the solution exceeds 5 wt%, the thickness of the SiO 2 protective film becomes thicker than 0.2 μm, while if the SiO 2 conversion concentration is less than 0.1 wt%, S
This is because the thickness of the iO 2 protective film is less than 0.01 μm.
【0013】上述のようにしてアルコール希釈したアル
コール希釈溶液に、Mn−Bi系磁性粉末を浸漬し、ろ
別後室温で攪拌しながら乾燥するとMn−Si系磁性粉
末の表面にSi(OH)4 モノマーの皮膜が一様に形成
され、このSi(OH)4 モノマー皮膜が形成されたM
n−Bi系磁性粉末を加熱するとSi(OH)4 モノマ
ーが縮合反応し、Mn−Bi系磁性粉末の表面にSiO
2 皮膜が形成される。The Mn-Bi magnetic powder was immersed in the alcohol-diluted solution diluted with alcohol as described above, filtered, and dried at room temperature with stirring to dry Si (OH) 4 on the surface of the Mn-Si magnetic powder. Monomer film is uniformly formed, and this Si (OH) 4 monomer film is formed on M
When the n-Bi magnetic powder is heated, the Si (OH) 4 monomer undergoes a condensation reaction to cause SiO 2 on the surface of the Mn-Bi magnetic powder.
2 A film is formed.
【0014】上記Si(OH)4 モノマーに縮合反応を
起こさせる加熱雰囲気は、真空またはAr、N2 ガスな
どの不活性ガス雰囲気が好ましく、その加熱温度は縮合
反応を促進するために150℃以上が望ましく、また3
50℃を越えるとMn−Bi系磁性粉末の金属組織変化
が起こるのでその上限は350℃以下が望ましい。The heating atmosphere for causing the condensation reaction of the Si (OH) 4 monomer is preferably vacuum or an atmosphere of an inert gas such as Ar or N 2 gas, and the heating temperature is 150 ° C. or higher for promoting the condensation reaction. Is desirable, and 3
If the temperature exceeds 50 ° C, the metallic structure of the Mn-Bi magnetic powder changes, so the upper limit is preferably 350 ° C or less.
【0015】[0015]
【実施例】MnおよびBiを共に高周波溶解炉に装入
し、Ar雰囲気中で溶解し、鋳造して表1〜表2に示さ
れる成分組成のMn−Bi系合金鋳塊を作製し、このM
n−Bi系合金鋳塊をAr雰囲気中、400℃、100
時間保持の熱処理を施したのち、アトライタミルにより
トルエン溶媒中で微粉砕し、得られたMn−Bi系合金
粉末の粒径(d50)をレーザー回折式粒度分布計で測定
し、この測定結果を表1〜表2に示した。EXAMPLE Mn and Bi were both charged into a high-frequency melting furnace, melted in an Ar atmosphere, and cast to prepare Mn-Bi alloy ingots having the component compositions shown in Tables 1 and 2. M
The n-Bi alloy ingot is placed in an Ar atmosphere at 400 ° C. for 100
After the heat treatment for holding for a while, the particles were pulverized in a toluene solvent with an attritor mill, and the particle size (d 50 ) of the obtained Mn-Bi alloy powder was measured with a laser diffraction type particle size distribution meter. The results are shown in Tables 1 and 2.
【0016】次いでテトラエチルオルトシリケート(T
EOS)をイソプロピルアルコールで溶解し、40.9
wt%TEOSアルコール溶液を作製し、この40.9wt
%TEOSアルコール溶液に対して触媒として0.3wt
%硝酸水溶液を7.1wt%添加し攪拌したのち24時間
放置した。Next, tetraethyl orthosilicate (T
EOS) is dissolved in isopropyl alcohol and 40.9
A wt% TEOS alcohol solution was prepared and this 40.9 wt
0.3wt% as catalyst for% TEOS alcohol solution
% Nitric acid aqueous solution was added and the mixture was stirred and then allowed to stand for 24 hours.
【0017】このようにして得られた溶液をさらにイソ
プロピルアルコールで希釈し、SiO2 換算で表1〜表
2に示される濃度のアルコール希釈溶液を作製した。The solution thus obtained was further diluted with isopropyl alcohol to prepare alcohol diluted solutions having the concentrations shown in Tables 1 and 2 in terms of SiO 2 .
【0018】このアルコール希釈溶液に表1〜表2に示
されるd50の粒径を有するMn−Bi系合金粉末を浸漬
し、ろ別したのち室温で攪拌しながら乾燥し、Mn−B
i系合金粉末表面にSi(OH)4 皮膜を形成し、つい
で2×10-5torrの真空雰囲気中、温度:250℃で1
時間加熱してSiO2 保護皮膜を有する本発明表面被覆
Mn−Bi系磁気記録粉末(以下、本発明記録粉とい
う)1〜18および比較表面被覆Mn−Bi系磁気記録
粉末(以下、比較記録粉という)1〜2を作製した。Mn-Bi alloy powders having a particle size of d 50 shown in Tables 1 and 2 were dipped in the diluted alcohol solution, filtered, and dried at room temperature with stirring to obtain Mn-B.
A Si (OH) 4 film is formed on the surface of the i-based alloy powder, and then in a vacuum atmosphere of 2 × 10 −5 torr at a temperature of 250 ° C. for 1 hour.
The surface-coated Mn-Bi magnetic recording powders of the present invention (hereinafter referred to as the recording powders of the present invention) 1 to 18 and the comparative surface-coated Mn-Bi magnetic recording powders (hereinafter referred to as the comparative recording powders) which have been heated for a time and have a SiO 2 protective film. 1) and 2 were produced.
【0019】これら本発明記録粉1〜18および比較記
録粉1〜2をレーザー回折式粒度分布計で測定し、粒径
(D50)を表1〜表2に示し、d50およびD50の測定値
からSiO2 保護皮膜の厚さ:1/2(D50−d50)を
求めてその結果を表1〜表2に示した。The recording powders 1 to 18 of the present invention and the comparative recording powders 1 to 2 were measured with a laser diffraction type particle size distribution meter, and the particle diameters (D 50 ) are shown in Tables 1 and 2, and d 50 and D 50 The thickness of the SiO 2 protective film: 1/2 (D 50 -d 50 ) was determined from the measured values, and the results are shown in Tables 1 and 2.
【0020】得られた本発明記録粉末1〜18および比
較記録粉末1〜2を大気中で表1〜表2に示される温度
に表1〜表2に示される時間加熱保持したのち、本発明
記録粉末1〜18および比較記録粉末1〜2の保磁力お
よび飽和磁化を測定し、その結果を表1〜表2に示し
た。The obtained recording powders 1 to 18 of the present invention and the comparative recording powders 1 to 2 were heated and held in the atmosphere at the temperatures shown in Tables 1 and 2 for the times shown in Tables 1 and 2, and then the present invention. The coercive force and the saturation magnetization of the recording powders 1 to 18 and the comparative recording powders 1 and 2 were measured, and the results are shown in Tables 1 and 2.
【0021】比較のために、Mn−Bi系合金粉末をジ
ヘキシルアミンナイトライト1.5部およびメチルイソ
ブチルケトン400部と共にアトライタミルにより粉砕
し、Mn−Bi系合金粉末の表面に厚さ:0.10およ
び0.15μmの含窒素防錆皮膜を有する従来表面被覆
Mn−Bi系磁気記録粉末(以下、従来記録粉という)
1〜2を作製し、この従来記録粉1〜2を表2に示され
る温度および時間保持したのち、それらの保磁力および
飽和磁化を測定し、その結果を表2に示した。For comparison, the Mn-Bi alloy powder was pulverized with 1.5 parts of dihexylamine nitrite and 400 parts of methyl isobutyl ketone by an attritor mill, and the surface of the Mn-Bi alloy powder had a thickness of 0.10. And a conventional surface-coated Mn-Bi magnetic recording powder having a nitrogen-containing anticorrosion coating of 0.15 μm (hereinafter referred to as conventional recording powder)
Nos. 1 and 2 were prepared, and the conventional recording powders 1 and 2 were held at the temperatures and the times shown in Table 2, and their coercive force and saturation magnetization were measured. The results are shown in Table 2.
【0022】[0022]
【表1】 [Table 1]
【0023】[0023]
【表2】 [Table 2]
【0024】表1および表2に示される結果から、本発
明記録粉1〜18はいずれも従来記録粉1〜2に比べて
特に高温に長時間保持した場合に磁気特性の低下が少な
いことがわかる。しかし、比較記録粉1〜2に見られる
ようにSiO2 保護皮膜が厚すぎても薄すぎても十分な
効果が得られないこともわかる。From the results shown in Tables 1 and 2, all of the recording powders 1 to 18 of the present invention show less deterioration in magnetic characteristics than the conventional recording powders 1 and 2, especially when kept at a high temperature for a long time. Recognize. However, as can be seen from the comparative recording powders 1 and 2, it cannot be seen that a sufficient effect cannot be obtained if the SiO 2 protective film is too thick or too thin.
【0025】[0025]
【発明の効果】上述のように、この発明の表面被覆Mn
−Bi系磁気記録粉末は、常温にあっては勿論のこと、
高温に長時間さらされても磁気特性は低下しないところ
から、この発明の表面被覆Mn−Bi系磁気記録粉末を
用いて常温および高温において使用可能な磁気記録媒体
を提供することができ、産業の発展に大いに貢献しうる
ものである。As described above, the surface coating Mn of the present invention is used.
-Of course, the Bi-based magnetic recording powder is at room temperature,
Since the magnetic characteristics do not deteriorate even when exposed to high temperature for a long time, the surface-coated Mn-Bi magnetic recording powder of the present invention can be used to provide a magnetic recording medium that can be used at room temperature and high temperature. It can greatly contribute to the development.
Claims (2)
素保護皮膜が形成されていることを特徴とする表面被覆
Mn−Bi系磁気記録粉末。1. A surface-coated Mn-Bi-based magnetic recording powder having a protective film of silicon dioxide formed on the surface of the Mn-Bi-based magnetic powder.
ル反応によりMn−Bi系磁性粉末表面に二酸化ケイ素
保護皮膜を形成することを特徴とする表面被覆Mn−B
i系磁気記録粉末の製造方法。2. A surface-coated Mn-B, characterized in that a silicon dioxide protective film is formed on the surface of the Mn-Bi magnetic powder by a sol-gel reaction using a silicon alkoxide.
Method for producing i-based magnetic recording powder.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7079745A JPH08246002A (en) | 1995-03-10 | 1995-03-10 | Surface-coated mn-bi magnetic recording powder and its production |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7079745A JPH08246002A (en) | 1995-03-10 | 1995-03-10 | Surface-coated mn-bi magnetic recording powder and its production |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH08246002A true JPH08246002A (en) | 1996-09-24 |
Family
ID=13698771
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP7079745A Withdrawn JPH08246002A (en) | 1995-03-10 | 1995-03-10 | Surface-coated mn-bi magnetic recording powder and its production |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH08246002A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1063639A1 (en) * | 1999-06-24 | 2000-12-27 | Toda Kogyo Corporation | Magnetic composite particles for magnetic recording medium, process for producing the same and magnetic recording medium using the same |
JP2008302098A (en) * | 2007-06-11 | 2008-12-18 | Fujifilm Corp | Ultrasonic probe, backing for ultrasonic probe, and method for producing the backing |
-
1995
- 1995-03-10 JP JP7079745A patent/JPH08246002A/en not_active Withdrawn
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1063639A1 (en) * | 1999-06-24 | 2000-12-27 | Toda Kogyo Corporation | Magnetic composite particles for magnetic recording medium, process for producing the same and magnetic recording medium using the same |
JP2008302098A (en) * | 2007-06-11 | 2008-12-18 | Fujifilm Corp | Ultrasonic probe, backing for ultrasonic probe, and method for producing the backing |
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