JP4929473B2 - Magnetic powder for magnetic recording medium, method for producing the same, and magnetic recording medium using the same - Google Patents
Magnetic powder for magnetic recording medium, method for producing the same, and magnetic recording medium using the same Download PDFInfo
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Description
本発明は、磁気記録媒体に使用する耐酸化性に優れた磁性粉末に関するものである。 The present invention relates to a magnetic powder having excellent oxidation resistance used for a magnetic recording medium.
家庭用ＡＶ機器用テープおよびデータバックアップ用ストレージテープといった磁気記録媒体は近年高密度化、高画質化を向上させる目的から広く検討が行われるようになっている。
具体的には、現在精力的に検討されている用途として、コンピューター用途のデータストレージテープがあげられる。データストレージ用途は高容量化、すなわち小さな記録領域に出来るだけ多くの情報を書き込むことが絶えず試みられている。高密度化が進行していくにつれて、情報の仲立ちとなる磁性粉末に対しても出来るだけ小さいもの、すなわち微粒子が望まれるようになっている。
In recent years, magnetic recording media such as home AV equipment tapes and data backup storage tapes have been widely studied for the purpose of increasing the density and improving the image quality.
Specifically, data storage tapes for computer use are examples of applications that are currently being studied energetically. For data storage applications, attempts are constantly made to increase the capacity, that is, to write as much information as possible in a small recording area. As the density increases, the magnetic powder that serves as a mediator of information is desired to be as small as possible, that is, fine particles.
しかし、磁性粒子の微粒子化には大きな問題があることが指摘されている。その中の最たるものが粒子自体の酸化安定性である。酸化安定性の悪い粒子を磁気記録媒体に使用すると、従来公知の情報にも多く示されているように保持がうまくいかず、情報の保存安定性に著しい悪影響を及ぼすことが知られている。そのため、磁性粒子の酸化安定性改善の試みは様々な観点から行われている。
たとえば、弱酸化性ガスや酸素ガスを不活性ガス中に投入して粒子表面を酸化させる方法（例えば特許文献１参照）、還元後に酸化処理、不活性雰囲気下でのアニール処理を行う方法（例えば特許文献２参照）、不活性ガス中での１００〜５００℃の加熱処理（例えば特許文献３参照）、酸化処理を施した後に不活性ガス下で８０〜６００℃の温度で０.５〜２４時間アニール処理して再酸化する方法（例えば特許文献４参照）、また、流動床を用いて徐酸化処理を行った後に不活性ガス雰囲気下で１５０〜６００℃の温度で０.２〜２４時間加熱処理した後に再酸化処理を行う方法（例えば特許文献５参照）が示されている。
However, it has been pointed out that there are significant problems in making magnetic particles fine. The most important of these is the oxidation stability of the particles themselves. When particles having poor oxidation stability are used in a magnetic recording medium, it is known that retention is not successful as shown in many conventionally known information, and the storage stability of information is significantly adversely affected. Therefore, attempts to improve the oxidation stability of magnetic particles have been made from various viewpoints.
For example, a method in which a weak oxidizing gas or oxygen gas is introduced into an inert gas to oxidize the particle surface (for example, see Patent Document 1), an oxidation treatment after reduction, and a method for performing an annealing treatment in an inert atmosphere (for example, Patent Document 2), heat treatment at 100 to 500 ° C. in an inert gas (see, for example, Patent Document 3), oxidation treatment, and 0.5 to 24 at a temperature of 80 to 600 ° C. under an inert gas. A method of re-oxidation by annealing for a period of time (see, for example, Patent Document 4), and after performing gradual oxidation treatment using a fluidized bed, at a temperature of 150 to 600 ° C. in an inert gas atmosphere for 0.2 to 24 hours A method of performing re-oxidation treatment after heat treatment (see, for example, Patent Document 5) is shown.
また、粒子の表面に関する検討としては、ＥＳＣＡによる組成を規定したもの（例えば特許文献６参照）があげられ、耐酸化性の向上のためには表面における組成が重要な役割を果たしうることが公知の条件のものとして広く知られているところである。
しかしながら、微粒子化に伴う耐酸化性の改善については現在でも広く検討がなされていることからも明らかなとおり、未だ技術として確立し切れていない。
However, as is clear from the fact that the improvement in oxidation resistance associated with the formation of fine particles is still widely studied, it has not been established as a technology yet.
上記に述べたとおり、従来公知の発明では耐酸化性に関する問題が完全に解決しているわけではなく、さらなる改善が求められている。そこで、本発明が解決すべき課題は酸化安定性に優れた磁気記録媒体用磁性粉末の提供である。 As described above, the conventional known invention does not completely solve the problem regarding oxidation resistance, and further improvement is required. Therefore, the problem to be solved by the present invention is to provide a magnetic powder for magnetic recording media having excellent oxidation stability.
先に述べた技術的な課題は次に示すような方法により解決しうる。
本発明者らは、いかにして磁気特性を維持しつつ耐酸化性の改善を図るか、という一点について種々な観点から検討を行ってきた。その際着目したのは、還元後の粉末のハンドリングもしくは処理をいかにして行うかという点である。
具体的には、本発明者らは還元後に酸素により酸化膜形成処理を行った後に、活性を持った気体中、例えば還元能力を持ったＣＯやＨ2などにより緩やかな気相活性化処理を行うことによって酸化膜の状態を変化させた。
このときのＥＳＣＡにより測定される結合エネルギーのピークの発現位置は処理を行わなかったものと比較してピークが低エネルギー側にシフトしており、通常公知の方法で得られる酸化膜の構造とは異なっているものが得られていることがわかった。得られた酸化膜の構造は一概には同定できないが、難酸化性の物質に変化しているものと推測できる。
本方法では、従来公知の技術で示されていたような異種金属の添加など磁気特性に必ずしも好影響を及ぼさない要因を排除できるため好適な磁性粉末の提供を行うことが出来る。
The technical problems described above can be solved by the following method.
The inventors of the present invention have studied from various points of view how to improve the oxidation resistance while maintaining the magnetic characteristics. At that time, the focus was on how to handle or process the powder after reduction.
Specifically, the present inventors performed an oxide film formation process with oxygen after reduction, and then performed a gentle gas-phase activation process with an active gas such as CO or H 2 having a reducing ability. By doing so, the state of the oxide film was changed.
The peak position of the binding energy measured by ESCA at this time is shifted to a lower energy side compared to the case where the treatment was not performed, and what is the structure of the oxide film obtained by a generally known method? I found that something different was obtained. Although the structure of the obtained oxide film cannot be generally identified, it can be assumed that the oxide film has been changed to a hardly oxidizable substance.
In this method, it is possible to provide a suitable magnetic powder because it is possible to eliminate factors that do not necessarily have a positive effect on magnetic properties, such as the addition of different metals as shown in the prior art.
すなわち本発明は第１に、ＣｏをＣｏ／Ｆｅ原子％比で４０％以下の範囲で含有し、かつその表面に酸化膜が形成されてなり、ＥＳＣＡにより測定される結合エネルギーピークを５２５〜５３２ｅＶに有することを特徴とする磁気記録媒体用金属磁性粉末；第２に、温度６０℃、相対湿度９０％の恒温恒湿下に一週間保持したときの飽和磁化量の低下率Δσｓが１５％未満である第１記載の磁気記録媒体用金属磁性粉末。ただし、該恒温恒湿下に保持する前の飽和磁化量をσｓ（ｉ）、一週間保持後の飽和磁化量をσｓ（ｉｉ）としたとき、Δσｓ＝１００×〔σｓ（ｉ）−σｓ（ｉｉ）〕／σｓ（ｉ）で表される；第３に、水蒸気を添加した雰囲気中の還元処理により得られたＣｏをＣｏ／Ｆｅ原子％比で４０％以下の範囲で含有する金属合金粉末を水蒸気を添加した雰囲気中で酸化処理し、次いで水蒸気を添加した還元性を有する気体により該粉末表面を還元した後、再度水蒸気を添加した雰囲気中で酸化処理することを特徴とする磁気記録媒体用金属磁性粉末の製造方法；第４に、前記還元処理される被還元物質がオキシ水酸化鉄である第３記載の製造方法；第５に、前記還元処理される被還元物質がα−酸化鉄である第３記載の製造方法；第６に、磁性層を構成する磁性粉末として第１または２に記載の金属磁性粉末を用いた磁気記録媒体である。 That is, the present invention firstly includes Co in a Co / Fe atomic ratio of 40% or less and an oxide film is formed on the surface thereof. The binding energy peak measured by ESCA is 525 to 532 eV. Metal magnetic powder for magnetic recording media characterized in that: Second, the rate of decrease Δσs in saturation magnetization when held at a constant temperature and humidity of 60 ° C. and 90% relative humidity for less than 15% is less than 15% The metal magnetic powder for magnetic recording media as described in 1 above. However, when the saturation magnetization before holding under constant temperature and humidity is σs (i) and the saturation magnetization after holding for one week is σs (ii), Δσs = 100 × [σs (i) −σs ( ii)] / σs (i); Third, a metal alloy powder containing Co obtained by reduction treatment in an atmosphere to which water vapor has been added in a Co / Fe atomic% ratio of 40% or less. the oxidation treatment in an atmosphere supplemented with steam, then after reduction of the powder surface by the gas with the reducing added steam, magnetic recording medium, characterized in that the oxidation treatment in an atmosphere supplemented with steam again fourth, the manufacturing method of the third aspect the reducible substance is an iron oxyhydroxide is reduced processed; production method of use metallic magnetic powder to the fifth, the reducible substance is the reduction treatment α- oxide the third method of manufacturing wherein the iron; sixth, structure of the magnetic layer A magnetic recording medium using the metal magnetic powder according to the first or 2 as the magnetic powder.
本発明に係る磁気記録媒体用磁性粉末はΔσsが１５％未満と小さいものであって、顕著に改善された耐酸化性特性を有する。 The magnetic powder for magnetic recording media according to the present invention has a small Δσs of less than 15%, and has significantly improved oxidation resistance characteristics.
本発明の構成についてさらに詳述する。
本発明に係る磁性粉末は、酸化膜の構成としてＥＳＣＡ（Electron Spectroscopy for Chemical Analysis：Ｘ線光電子分光法）にて測定した結合エネルギーのピーク（極大点）の発現位置がより低エネルギーの範囲、具体的には、５２５〜５３２ｅＶ（電子ボルト）、より好ましくは５２５〜５３１ｅＶの範囲にあることである。従来の酸化安定性の悪い酸化膜の発現位置は５３３ｅＶ程度にピークの発現を有するため、酸素の結合状態の異なる粒子となっている。
かような磁性粉末について、形状、形態についての制限はないが、通常磁性粉末として使用される形状のものが使用できうる。例えば、針状、紡錘状、平針状、粒状、棒状、楕円状などが主なものである。
The configuration of the present invention will be further described in detail.
In the magnetic powder according to the present invention, the position of the peak (maximum point) of the binding energy measured by ESCA (Electron Spectroscopy for Chemical Analysis) as the structure of the oxide film is in a lower energy range, specifically Specifically, it is in the range of 525 to 532 eV (electron volt), more preferably 525 to 531 eV. Since the conventional oxide film having poor oxidation stability has a peak at about 533 eV, the particles have different oxygen bonding states.
Although there is no restriction | limiting about a shape and a form about such a magnetic powder, The thing of the shape normally used as a magnetic powder can be used. For example, a needle shape, a spindle shape, a flat needle shape, a granular shape, a rod shape, an elliptical shape, and the like are main ones.
本発明に係る磁性粉末の作成方法として例示できるのは、オキシ水酸化鉄粒子を還元して金属鉄磁性粒子を生成させる方法や溶液中に存在する金属イオンを還元剤を用いて還元し金属鉄粒子を得る方法等が例示できるが、現在最も広く行われている金属磁性粒子の製造方法の一例である、オキシ水酸化鉄粒子からの金属鉄磁性粒子の製造方法を例として示す。
まず、前駆物質としてオキシ水酸化鉄を生成させる。オキシ水酸化鉄の製法としては炭酸塩水溶液に第一鉄塩水溶液を添加して炭酸鉄を生成させ、（適宜苛性アルカリを添加しても良い。）酸素含有ガスを添加して核晶を発生させた後、粒子を成長させオキシ水酸化鉄を形成させる方法や、第一鉄塩水溶液に対して苛性アルカリを単独で添加して、オキシ水酸化鉄を形成する反応などが例示できるが、本発明はオキシ水酸化鉄粒子の形状、製造方法には特に制約を受けない。
Examples of the method for producing the magnetic powder according to the present invention include a method of reducing iron oxyhydroxide particles to produce metal iron magnetic particles, and reducing metal ions present in a solution using a reducing agent to form metal iron. Although the method etc. which obtain particle | grains can be illustrated, the manufacturing method of the metal iron magnetic particle from the iron oxyhydroxide particle | grains which is an example of the manufacturing method of the metal magnetic particle currently performed most widely is shown as an example.
First, iron oxyhydroxide is generated as a precursor. Ferric oxyhydroxide is produced by adding ferrous salt aqueous solution to carbonate aqueous solution to produce iron carbonate (caustic alkali may be added as appropriate), and adding oxygen-containing gas to generate nuclei. Examples thereof include a method of growing particles to form iron oxyhydroxide and a reaction in which caustic is added alone to a ferrous salt aqueous solution to form iron oxyhydroxide. The invention is not particularly limited by the shape and manufacturing method of the iron oxyhydroxide particles.
本発明に係る粒子は後の還元による酸化膜の構造変化を論じるものであるため、磁性粒子の前駆体としては、コバルトを組成中に含むもの、またはコバルト化合物で粒子最表面が被覆されたもののいずれでも構わない。具体的には、コバルトをオキシ水酸化鉄の組成として含ませる場合であれば、炭酸塩の添加前に混合する方法や酸化反応途中に適宜添加するような場合のいずれでも構わないし、コバルト化合物で被覆する際にはいったん反応を完結させた後でコバルトを錯体の形［アンモニウムイオン、ＥＤＴＡ（Ethylene Diamine Tetraacetic Acid；エチレンジアミン四酢酸）との錯体等］で添加する方法や反応液のｐＨを適当に調整した上で水和イオンの形でコバルトを添加して、表面に被着する方法などが例示できる。
このときのＣｏ添加量の目安としては全体として、Ｃｏ／Ｆｅ（原子％比）が０〜５０％、好ましくは０〜４０％、より好ましくは０〜３５％である。この添加割合は保磁力や飽和磁化、酸化安定性などの要因から、最も好ましい割合を適宜選択して添加する。特に、Ｃｏ／Ｆｅが５０％を超える場合には単位体積当たりの飽和磁化量および耐酸化性の観点からみた特性のバランスが悪化してしまい好ましくない。
Since the particle according to the present invention discusses the structural change of the oxide film due to subsequent reduction, the precursor of the magnetic particle is one containing cobalt in the composition or the outermost surface of which is coated with a cobalt compound. Either is fine. Specifically, as long as cobalt is included as a composition of iron oxyhydroxide, either a method of mixing before the addition of carbonate or a case of adding it appropriately during the oxidation reaction may be used. When coating, once the reaction is completed, cobalt is added in the form of a complex [ammonium ion, complex with EDTA (Ethylene Diamine Tetraacetic Acid), etc.] and the pH of the reaction solution is adjusted appropriately. An example is a method in which cobalt is added in the form of hydrated ions after adjustment and deposited on the surface.
At this time, as a measure of the amount of Co added, the overall Co / Fe (atomic% ratio) is 0 to 50%, preferably 0 to 40%, more preferably 0 to 35%. This addition ratio is appropriately selected from the factors such as coercive force, saturation magnetization, oxidation stability, and the like. In particular, when Co / Fe exceeds 50%, the balance of characteristics from the viewpoint of saturation magnetization per unit volume and oxidation resistance deteriorates, which is not preferable.
本発明に係る磁性粒子はアルミニウムを、耐摩耗性改善、適当な硬度の付与、焼結防止効果、バインダーへの分散性改善などを目的として添加することが望ましい。その際の添加量はＡｌ／(Ｆｅ＋Ｃｏ)（原子％比）で０〜５０％、好ましくは１〜３０％、より好ましくは２〜１５％である。５０％を超えてアルミニウムを添加すると、粒子の有する硬度は高くなり研磨力は増加するものの、磁気特性なかでも飽和磁化の著しい低下を引き起こすため好ましくない。アルミニウムは核晶の生成段階初期には添加しない。これを怠った場合には、粒子の針状性が保持されないため、形状磁気異方性に由来する磁気特性が十分に得られなくなる。そのため、適当な添加時期としては、ある程度粒子の形状が整いつつある成長段階中から酸化終了直前にかけて添加することが適当である。 The magnetic particles according to the present invention preferably contain aluminum for the purpose of improving wear resistance, imparting appropriate hardness, preventing sintering, improving dispersibility in a binder, and the like. The addition amount at that time is 0 to 50%, preferably 1 to 30%, more preferably 2 to 15% in terms of Al / (Fe + Co) (atomic% ratio). If aluminum is added in excess of 50%, the hardness of the particles increases and the polishing power increases, but this is not preferable because it causes a significant decrease in saturation magnetization even in the magnetic properties. Aluminum is not added early in the nucleation stage. If this is neglected, the acicularity of the particles will not be maintained, so that sufficient magnetic properties derived from shape magnetic anisotropy will not be obtained. Therefore, as an appropriate addition time, it is appropriate to add from the growth stage where the shape of the particles is being adjusted to some extent to just before the end of oxidation.
本発明に係る磁性粒子には希土類元素の添加については妨げない。希土類元素の添加効果としては、磁性粒子の形状保持効果、焼結防止効果および粒度分布改善効果があげられる。希土類元素（Ｙを含む。）Ｒの望ましい添加範囲としては、Ｒ／（Ｆｅ＋Ｃｏ）原子％比で０〜２５％、好ましくは１〜２０％、より好ましくは２〜１５％である。Ｒが２５％を超える場合は、磁気特性の著しい低下を引き起こすため好ましくない。添加時期としては、オキシ水酸化鉄の成長段階での添加でもいいし、成長終了後添加のいずれの場合であっても構わない。
本発明に係る磁性粒子には、製造工程上不可避な成分の他、磁気特性もしくはバインダーに対するなじみの向上、すなわちバインダーに対する分散性の向上のために好適になる成分の添加を妨げない。
The magnetic particles according to the present invention do not interfere with the addition of rare earth elements. Examples of the effect of adding rare earth elements include the effect of maintaining the shape of magnetic particles, the effect of preventing sintering, and the effect of improving particle size distribution. A desirable addition range of the rare earth element (including Y) R is 0 to 25%, preferably 1 to 20%, and more preferably 2 to 15% in the R / (Fe + Co) atomic% ratio. When R exceeds 25%, it is not preferable because it causes a significant decrease in magnetic properties. The addition time may be the addition of iron oxyhydroxide at the growth stage, or may be added after the growth is completed.
In addition to the components that are inevitable in the production process, the magnetic particles according to the present invention do not interfere with the addition of components that are suitable for improving the magnetic properties or familiarity with the binder, that is, improving the dispersibility with respect to the binder.
以上の工程を経て、コバルト含有のオキシ水酸化鉄を得た。こうして得られたオキシ水酸化鉄について、常法により濾過、水洗、乾燥を施す。乾燥温度としては８０〜３００℃、好ましくは１００〜２５０℃、より好ましくは１２０〜２２０℃の範囲で行う。３００℃を超える場合には乾燥は行えるがヘマタイト化が不均一に進んでしまうため好ましくなく、８０℃未満の場合では水分が十分に抜けずに不均一な還元の原因になりうる。 Through the above steps, cobalt-containing iron oxyhydroxide was obtained. The iron oxyhydroxide thus obtained is filtered, washed with water and dried by a conventional method. The drying temperature is 80 to 300 ° C, preferably 100 to 250 ° C, more preferably 120 to 220 ° C. If it exceeds 300 ° C., drying can be performed, but hematite formation proceeds nonuniformly, which is not preferable. If it is less than 80 ° C., moisture cannot be sufficiently removed and nonuniform reduction may be caused.
得られたオキシ水酸化鉄絶乾物を常法によりα−ヘマタイト等の酸化鉄に変換して実施することも可能である。このときの粒子の保持条件としては、ガス通気可能なバケットの中に静置してＮ2ガスを通気させつつ変化させる方法や粒子を回転可能な炉内に導入した上、回転させながら粒子を変化させる方法などがあげられるが、いずれの方法であっても構わない。このときの焼成温度としては２５０〜７５０℃、好ましくは３００〜６００℃、より好ましくは３５０〜５５０℃である。焼成時における雰囲気には水蒸気、炭酸ガスといったガスの存在があることを妨げない。焼成温度が２５０℃未満の場合には、オキシ水酸化鉄からα−酸化鉄（ヘマタイト）への形態変換が不均一となる可能性があり適当でない。また７５０℃を超える温度での焼成も可能ではあるが、粒子の焼結が進んでしまうため好ましくない。 It is also possible to carry out by converting the obtained iron oxyhydroxide absolute dry matter into iron oxide such as α-hematite by a conventional method. The particle holding conditions at this time include a method of changing the particles while allowing them to stand in a gas-permeable bucket and introducing N 2 gas, or introducing particles into a rotatable furnace, and then rotating the particles while rotating them. Although the method of changing is mention | raise | lifted, any method may be used. As a calcination temperature at this time, it is 250-750 degreeC, Preferably it is 300-600 degreeC, More preferably, it is 350-550 degreeC. It does not prevent the presence of gas such as water vapor and carbon dioxide in the atmosphere during firing. When the calcination temperature is less than 250 ° C., the form conversion from iron oxyhydroxide to α-iron oxide (hematite) may be non-uniform, which is not appropriate. Further, although firing at a temperature exceeding 750 ° C. is possible, it is not preferable because the sintering of the particles proceeds.
そうして得られたオキシ水酸化鉄もしくは酸化鉄系粒子を気相還元する。還元性のガスの種類としては一酸化炭素、水素、アセチレンなどがあげられる。こうした還元は一段目の温度と二段目の温度を変化させる、いわゆる多段還元の方法を用いてもよい。ここで言う多段還元とは、一段目の還元を比較的低温を維持して還元した上で昇温工程を経て、比較的高温を維持して還元を行うものである。低温還元温度は３００〜６００℃、好ましくは３００〜５５０℃とし、高温還元温度は３５０〜７００℃、好ましくは３５０〜６５０℃とする。 The iron oxyhydroxide or iron oxide particles thus obtained are subjected to gas phase reduction. Examples of the reducing gas include carbon monoxide, hydrogen, and acetylene. For such reduction, a so-called multistage reduction method in which the temperature of the first stage and the temperature of the second stage are changed may be used. The multistage reduction referred to here is to perform the reduction while maintaining the relatively high temperature through the temperature raising step after reducing the first stage while maintaining the relatively low temperature. The low temperature reduction temperature is 300 to 600 ° C, preferably 300 to 550 ° C, and the high temperature reduction temperature is 350 to 700 ° C, preferably 350 to 650 ° C.
得られた磁性金属粒子は活性が非常に高いことから、表面に安定化酸化膜を形成させる必要がある。このとき本発明では酸素含有ガス雰囲気中で２００℃以下、好ましくは１８０℃以下、より好ましくは１５０℃以下の温度で酸化膜形成処理を行う。２００℃を超えた温度での酸化膜形成処理も可能であるが、酸化膜が厚くなりすぎるため好ましくない。
次いで、炉内雰囲気を切り替え、活性を持った気体を導入、例えば還元能力を持ったＣＯやＨ2などにより緩やかな気相活性化処理を行うことによって酸化膜の状態を変化させた。その後再び酸素含有ガスを導入して酸化膜をさらに形成させた。このときの気相活性化処理温度（アニール処理温度）としては１００℃未満の場合ではアニール処理によってもたらされる酸化膜の改善効果が低下し、Δσｓの改善効果が低下してしまうため好ましくない。一方、５００℃を超える場合にもアニール処理の効果が薄れてしまい、Δσｓの改善効果が低下してしまうため好ましくない。従って、アニール処理の好ましい温度範囲としては、１００〜５００℃、好ましくは１５０〜４５０℃、より好ましくは２００〜４００℃で行うことが望ましい。
Since the obtained magnetic metal particles have very high activity, it is necessary to form a stabilized oxide film on the surface. At this time, in the present invention, the oxide film forming process is performed at a temperature of 200 ° C. or less, preferably 180 ° C. or less, more preferably 150 ° C. or less in an oxygen-containing gas atmosphere. Although an oxide film formation process at a temperature exceeding 200 ° C. is possible, it is not preferable because the oxide film becomes too thick.
Next, the atmosphere in the furnace was switched, an active gas was introduced, and the state of the oxide film was changed by, for example, performing a gentle gas-phase activation treatment with CO or H 2 having a reducing ability. Thereafter, an oxygen-containing gas was again introduced to further form an oxide film. If the vapor phase activation temperature (annealing temperature) at this time is less than 100 ° C., the improvement effect of the oxide film caused by the annealing treatment is lowered, and the improvement effect of Δσs is lowered. On the other hand, when the temperature exceeds 500 ° C., the effect of annealing treatment is diminished, and the effect of improving Δσs is lowered, which is not preferable. Accordingly, the preferable temperature range for the annealing treatment is 100 to 500 ° C., preferably 150 to 450 ° C., more preferably 200 to 400 ° C.
以下に本発明の実施例を記載するが、本発明の技術的範囲はこれらの記載に制限されるものではないことはいうまでもない。 Examples of the present invention are described below, but it goes without saying that the technical scope of the present invention is not limited to these descriptions.
本発明で得られる物質の組成、磁気特性は以下のようにして分析した。
［組成分析］
表面分析は、Ｘ線光電子分光法（ＥＳＣＡ）、オージエ電子分光法（ＡＥＳ；Auger Electron Spectroscopy）を用いることが広く行われている。本発明ではＥＳＣＡを用いて測定した結果について示す。測定条件としては、アルバック・ファイ株式会社製の５８００を使用し、取り出し角は４５°に設定し、試料はホルダに設置する形でセッティングした。Scanning Speedは５ｅＶ／分でありエッチングは２ｎｍ／cycleの割合で行い、１０cycle（２０ｎｍ）の値で粒子表面の組成として算出した。また測定範囲は、酸素O(1S)の出現個所に該当する５２５〜５４５ｅＶの範囲で測定している。
The composition and magnetic properties of the substance obtained by the present invention were analyzed as follows.
[Composition analysis]
For surface analysis, X-ray photoelectron spectroscopy (ESCA) and Auger electron spectroscopy (AES) are widely used. In this invention, it shows about the result measured using ESCA. As measurement conditions, 5800 manufactured by ULVAC-PHI Co., Ltd. was used, the take-off angle was set to 45 °, and the sample was set in a form installed in a holder. Scanning Speed was 5 eV / min, etching was performed at a rate of 2 nm / cycle, and the composition of the particle surface was calculated at a value of 10 cycles (20 nm). The measurement range is a range of 525 to 545 eV corresponding to the appearance location of oxygen O (1S).
全体組成分析については、Ｃｏ、Ａｌ、Ｙの定量は日本ジャーレルアッシュ株式会社製の高周波プラズマ発光分析装置（ＩＲＩＳ／ＡＰ）、Ｆｅの定量は平沼産業株式会社製の平沼自動滴定装置（ＣＯＭＴＩＭＥ−９８０）を用いて行った。これらの定量結果は重量％（ｗｔ％と表す。）として与えられるため、算出時には原子％（ａｔ％と表す。）に変換させた。 For the total composition analysis, Co, Al, and Y were quantified by Nihon Jarrel Ash Co., Ltd., high-frequency plasma emission analyzer (IRIS / AP), and Fe was quantified by Hiranuma Sangyo Co., Ltd. 980). Since these quantitative results are given as weight% (expressed as wt%), they were converted to atomic% (expressed as at%) at the time of calculation.
［粒子の長軸長及び短軸長］
平均長軸長並びに短軸長は透過型電子顕微鏡にて観察された視野を１７４０００倍に拡大した写真を使用して、５００個の粒子を測定し平均で示した。測定は粒子の重なりなどの写真の写り方によって境界のはっきりしないもの、写真の端で粒子の端が不正確になっているものに関しては測定を避け、分散のよい単独粒子のみを選択して計測している。
[Long axis length and short axis length of particles]
The average major axis length and the minor axis length were measured and averaged by measuring 500 particles using a photograph in which the field of view observed with a transmission electron microscope was magnified 174,000 times. Measurement is not possible for the case where the boundary is not clear due to the way the photo is taken, such as particle overlap, or the case where the end of the particle is inaccurate at the end of the photo, and only single particles with good dispersion are selected and measured. is doing.
［磁気特性および耐酸化性評価］
磁気特性は東栄工業株式会社製のＶＳＭ装置（ＶＳＭ−７Ｐ）を使用して外部磁場１０ｋOe（１２５.６ｋＡ／ｍ）で測定した。
耐酸化性評価は設定温度６０℃、相対湿度９０％の恒温恒湿の環境下に一週間保持して、該恒温恒湿下に保持する前の飽和磁化量σs(i)、一週間保持後の飽和磁化量σs(ii)を測定し、保存前後の飽和磁化量の低下率Δσs
Δσs＝１００×〔σs(i)−σs(ii)〕／σs(i)
の算出式により評価した。
[Evaluation of magnetic properties and oxidation resistance]
The magnetic properties were measured with an external magnetic field of 10 kOe (125.6 kA / m) using a VSM device (VSM-7P) manufactured by Toei Kogyo Co., Ltd.
Oxidation resistance evaluation is maintained for one week in a constant temperature and humidity environment with a set temperature of 60 ° C. and a relative humidity of 90%, and the saturation magnetization amount σs (i) before being held under the constant temperature and humidity for one week. The saturation magnetization amount σs (ii) is measured, and the decrease rate of the saturation magnetization amount before and after storage Δσs
Δσs = 100 × [σs (i) −σs (ii)] / σs (i)
Evaluation was performed using the following formula.
また、媒体の保存安定性評価として、保存前後のテープ化した小片を設定温度６０℃、相対湿度９０％の恒温恒湿の環境下に一週間保持して、該恒温恒湿下に保持した前後の最大磁束密度Ｂｍの値を測定し、その低下の状態を上記の粉末の飽和磁化σsに係るΔσsと同様にして、テープに係るΔＢｍの算出を行い評価した。すなわち媒体（テープ）を設定温度６０℃、相対湿度９０％の恒温恒湿の環境下に一週間保持して、該恒温恒湿下に保持する前のＢｍ(i)、一週間保持後のＢｍ(ii)を測定し、保存前後のＢｍの低下率ΔＢｍ（％）
ΔＢｍ＝１００×〔Ｂｍ(i)−Ｂｍ(ii)〕／Ｂｍ(i)
の算出式により評価した。
In addition, as a storage stability evaluation of the medium, the taped pieces before and after storage were kept in a constant temperature and humidity environment at a set temperature of 60 ° C. and a relative humidity of 90% for one week, and before and after being held under the constant temperature and humidity. The value of the maximum magnetic flux density Bm was measured, and in the same manner as the Δσs related to the saturation magnetization σs of the powder, ΔBm related to the tape was calculated and evaluated. That is, the medium (tape) is kept in a constant temperature and humidity environment of a set temperature of 60 ° C. and a relative humidity of 90% for one week, and Bm (i) before being held under the constant temperature and humidity and Bm after being held for one week. (ii) is measured, Bm decrease rate before and after storage ΔBm (%)
ΔBm = 100 × [Bm (i) −Bm (ii)] / Bm (i)
Evaluation was performed using the following formula.
［テープ評価］
テープ評価としては、強磁性鉄合金粉末１００重量部に対し以下の材料を下記組成となるような割合で配合して遠心ボールミルで１時間分散させて磁性塗料を作製し、この磁性塗料をポリエチレンテレフタレートからなるベースフイルム上にアプリケーターを用いて塗布することにより、磁気テープを作製し、その保磁力Hcxを測定し、またそのヒステリシスループから媒体のＳＦＤｘ（Switching Fieid Distribution；反転磁界分布）値を算出した。
強磁性鉄合金粉末 １００重量部
ポリウレタン樹脂(東洋紡製ＵＲ８２００) ３０重量部
メチルエチルケトン １９０重量部
シクロヘキサノン ８０重量部
トルエン １１０重量部
ステアリン酸 １重量部
アセチルアセトン １重量部
アルミナ ３重量部
カーボンブラック ２重量部
[Tape evaluation]
For tape evaluation, 100 parts by weight of ferromagnetic iron alloy powder was blended with the following materials in the proportions of the following composition, and dispersed with a centrifugal ball mill for 1 hour to prepare a magnetic paint. A magnetic tape was prepared by applying the film on a base film made of a magnetic film, the coercive force Hcx was measured, and the SFDx (Switching Fieid Distribution) value of the medium was calculated from the hysteresis loop. .
Ferromagnetic iron alloy powder 100 parts by weight Polyurethane resin (UR8200 manufactured by Toyobo) 30 parts by weight Methyl ethyl ketone 190 parts by weight Cyclohexanone 80 parts by weight Toluene 110 parts by weight Stearic acid 1 part by weight Acetylacetone 1 part by weight Alumina 3 parts by weight Carbon black 2 parts by weight
［比表面積］
湯浅イオニクス製の４ソープＵＳを用い、ＢＥＴ法を用いて算出した。
［Ｄｘ（結晶子サイズ）測定］
Ｘ線回折装置（理学電気株式会社製のＲＡＤ−２Ｃ）で得られる、Ｆｅ（１１０）面の回折ピークの半価幅、２θ式から、Ｄ（１１０）=Ｋλ／βcosθ〈式中、Ｋ：シェラー定数０.９、λ：照射Ｘ線波長、β：回折ピークの半価幅（ラジアン径に補正して用いる）、θ：回折角。〉に従って求める。
[Specific surface area]
It calculated using BET method using 4 soap US made from Yuasa Ionics.
[Dx (crystallite size) measurement]
Half-value width of diffraction peak of Fe (110) surface obtained by X-ray diffractometer (RAD-2C manufactured by Rigaku Corporation), 2θ equation, D (110) = Kλ / βcosθ where K: Scherrer constant 0.9, λ: irradiated X-ray wavelength, β: half width of diffraction peak (corrected to radians), θ: diffraction angle. Ask according to>.
［実施例１］ 第一鉄塩とコバルト塩の混合溶液から炭酸塩を経由して生成させたオキシ水酸化鉄を主成分とするケーキ(含まれる粒子の物性：長軸長０.０６２μm、軸比８.５、ＢＥＴ値１２９.７ｍ2／ｇ、Ｃｏ／Ｆｅのａｔ％比２０.３％、Ａｌ／（Ｆｅ＋Ｃｏ）のａｔ％比８.７％、Ｙ／（Ｆｅ＋Ｃｏ）のａｔ％比６.０％。表１中に示す。)を１３０℃にて乾燥して、オキシ水酸化鉄乾燥固形物を得た。その固形物７.６ｇをバケットに装入し、水蒸気を全体のガス流量の１０vol％（１.１３Ｌ／min・cm2）に相当する量の導入速度で添加しながら大気中にて３５０℃で焼成することで、α−ヘマタイトを主成分とする鉄系酸化物を得た。 [Example 1] A cake mainly composed of iron oxyhydroxide produced from a mixed solution of ferrous salt and cobalt salt via carbonate (physical properties of contained particles: major axis length: 0.062 μm, axis Ratio 8.5, BET value 129.7 m 2 / g, Co / Fe at% ratio 20.3%, Al / (Fe + Co) at% ratio 8.7%, Y / (Fe + Co) at% ratio 6 0.0% (shown in Table 1) was dried at 130 ° C. to obtain a dry iron oxyhydroxide solid. 7.6 g of the solid was charged into a bucket, and water vapor was added at 350 ° C. in the atmosphere while adding water vapor at an introduction rate corresponding to 10 vol% (1.13 L / min · cm 2 ) of the total gas flow rate. By firing, an iron-based oxide containing α-hematite as a main component was obtained.
そうして得られたα−ヘマタイトを主成分とする鉄酸化物を通気可能なバケット内に装入し、該バケットを貫通型還元炉内に装入し、水素ガス(１１.３２Ｌ／min・cm2)を通気しつつ、水蒸気を全体のガス流量の１０vol％（１.１３Ｌ／min・cm2）に相当する量の速度で添加しながら、４００℃で５分間還元処理を施した。還元時間終了後、水蒸気の供給を停止し、水素雰囲気下６００℃まで１０℃／分の昇温速度にて昇温させた。その後再度、水蒸気を全体のガス流量の１０vol％（１.１３Ｌ／min・cm2）に相当する量の速度で添加しながら１０分間高温還元処理を行い、還元鉄合金粉末を得た。 The iron oxide mainly composed of α-hematite thus obtained was charged into a bucket that can be ventilated, and the bucket was charged into a through-type reducing furnace, and hydrogen gas (11.32 L / min · while bubbling cm 2), while adding at a rate of an amount corresponding to 10 vol% of the gas flow rate of whole steam (1.13L / min · cm 2) , was subjected to 5 minutes reduced at 400 ° C.. After completion of the reduction time, the supply of water vapor was stopped, and the temperature was raised to 600 ° C. under a hydrogen atmosphere at a rate of temperature increase of 10 ° C./min. Thereafter, again, high-temperature reduction treatment was performed for 10 minutes while adding water vapor at a rate corresponding to 10 vol% (1.13 L / min · cm 2 ) of the total gas flow rate to obtain reduced iron alloy powder.
その後、炉内雰囲気を水素から窒素に変換し、１９.６６Ｌ／min・cm2の流速で炉内温度を降温レート２０℃／分で９０℃まで低下させた。そのあと、酸化膜形成初期段階は窒素１６.９０Ｌ／min・cm2と空気０.０８Ｌ／min・cm2の混合割合にて混合したガスを炉内に添加し、かつ水蒸気を全体のガス流量の１０vol％（１.７０Ｌ／min・cm2）に相当する量の速度で添加しながら、水蒸気・大気・窒素の混合雰囲気中にて酸化膜を形成させ、表面の酸化による発熱が抑制された段階で徐々に空気の供給量を増すことによって、雰囲気中における酸素濃度を上昇させた。最終的な空気の流量は０.７８Ｌ／min・cm2の添加量とした。その際には、炉内に導入される大気の総量調整は適宜窒素の流量を調整することで炉内の通気ガスの総量を一定にする。 Thereafter, the furnace atmosphere was converted from hydrogen to nitrogen, and the furnace temperature was lowered to 90 ° C. at a rate of temperature drop of 20 ° C./min at a flow rate of 19.66 L / min · cm 2 . Thereafter, in the initial stage of oxide film formation, a gas mixed at a mixing ratio of nitrogen 16.90 L / min · cm 2 and air 0.08 L / min · cm 2 is added to the furnace, and water vapor is added to the entire gas flow rate. While being added at a rate equivalent to 10 vol% (1.70 L / min · cm 2 ), an oxide film was formed in a mixed atmosphere of water vapor, air, and nitrogen, and heat generation due to surface oxidation was suppressed. The oxygen concentration in the atmosphere was increased by gradually increasing the air supply in stages. The final air flow rate was 0.78 L / min · cm 2 . In that case, the total amount of air introduced into the furnace is adjusted by appropriately adjusting the flow rate of nitrogen so that the total amount of vent gas in the furnace is constant.
そのあと、窒素雰囲気下において１０℃／分で３５０℃まで温度を上昇させた。引き続き、水素ガス(１１.３２Ｌ／min・cm2)を用い、水蒸気を全体のガス流量の１０vol％（１.１３Ｌ／min・cm2）に相当する量の速度で添加しながら３０分間還元した（アニール処理またはアニール工程という）。
その後、再度水素を窒素に切り替え、水蒸気の供給を停止した後に、降温操作に入り炉内温度を８０℃まで低下させた。窒素１６.９０Ｌ／min・cm2と空気０.０８Ｌ／min・cm2の混合割合にて混合したガスを、炉内に添加し、かつ水蒸気を全体のガス流量の１０vol％（１.７０Ｌ／min・cm2）に相当する量の速度で添加しながら、水蒸気・大気・窒素の混合雰囲気中にて酸化膜を形成させ、開始より１０分を経過した段階で空気の添加量を０.１６Ｌ／min・cm2にあげ、２０分を経過した段階で０.７８Ｌ／min・cm2の添加量とした。その後、１０分間そのままの状態を維持して、金属磁性粉末を得た。その際には、炉内に導入される大気の総量は適宜窒素の流量を調整することで酸化膜改良型磁性粉末を得た。
Thereafter, the temperature was raised to 350 ° C. at 10 ° C./min in a nitrogen atmosphere. Subsequently, hydrogen gas (11.32 L / min · cm 2 ) was used and reduced for 30 minutes while adding water vapor at a rate corresponding to 10 vol% (1.13 L / min · cm 2 ) of the total gas flow rate. (Referred to as annealing treatment or annealing process).
Then, after switching hydrogen to nitrogen again and stopping supply of water vapor | steam, it entered into temperature-fall operation and the furnace temperature was reduced to 80 degreeC. A gas mixed at a mixing ratio of 16.90 L / min · cm 2 of nitrogen and 0.08 L / min · cm 2 of air is added to the furnace, and water vapor is added to 10 vol% (1.70 L / min) of the total gas flow rate. While adding at a rate equivalent to min · cm 2 ), an oxide film is formed in a mixed atmosphere of water vapor, air and nitrogen, and after 10 minutes from the start, the amount of air added is 0.16 L. / listed min · cm 2, and the amount of 0.78L / min · cm 2 at the stage after the elapse of 20 minutes. Then, the state as it was for 10 minutes was maintained and metal magnetic powder was obtained. At that time, the total amount of air introduced into the furnace was adjusted by appropriately adjusting the flow rate of nitrogen to obtain an oxide film-modified magnetic powder.
得られた磁性粉末の磁気特性、テープ評価値並びに物性値について表２に示し、結合エネルギーピークを図１に示す。
これによれば、粉体の結合エネルギーピーク（極大点）は５３１.０ｅＶにあって、Δσsは８.２％と低く、これを前記のとおりテープ化したもののΔＢｍも２.４％と低く、粉体およびこれを用いたテープともに耐酸化性に優れたものであった。
The magnetic properties, tape evaluation values, and physical property values of the obtained magnetic powder are shown in Table 2, and the binding energy peak is shown in FIG.
According to this, the binding energy peak (maximum point) of the powder is 531.0 eV, Δσs is as low as 8.2%, and ΔBm of this taped as described above is as low as 2.4%, Both the powder and the tape using the powder were excellent in oxidation resistance.
［実施例２〜４］ 核粒子の組成を表１中の組成および物性値を有するものに変更した以外は実施例１と同様に行って磁性粉末を得た。磁性粉末特性値、テープ評価値を表２に示す。
粉体の結合エネルギーピークは実施例２では５３１.３ｅＶ、実施例３では５３１.９ｅＶ、実施例４では５２８.９ｅＶであった。
また、実施例２〜４においては、表２の記載のとおり、粉体のΔσsは５.３〜１０.２％と低く、これを前記のとおりテープ化したもののΔＢｍも１.７〜３.２％と低く、粉体およびこれを用いたテープともに耐酸化性に優れたものであった。
[Examples 2 to 4] Magnetic powders were obtained in the same manner as in Example 1 except that the composition of the core particles was changed to those having the composition and physical property values shown in Table 1. Table 2 shows the magnetic powder characteristic values and tape evaluation values.
The binding energy peak of the powder was 531.3 eV in Example 2, 531.9 eV in Example 3, and 528.9 eV in Example 4.
Further, in Examples 2 to 4, as described in Table 2, Δσs of the powder is as low as 5.3 to 10.2%, and ΔBm of the tape formed as described above is 1.7 to 3. As low as 2%, both the powder and the tape using the powder were excellent in oxidation resistance.
［実施例５〜８］ α−酸化鉄への転換を行わなかった以外は実施例１〜４と同様に行った実施例５〜８によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２に示す。粉体の結合エネルギーピークは実施例５では５２９.２ｅＶ、実施例６では５２７.３ｅＶ、実施例７では５２５.４ｅＶ、実施例８では５２６.９ｅＶであった。
また、実施例５〜８においては、表２の記載のとおり、粉体のΔσsは４.７〜７.０％と低く、これを前記のとおりテープ化したもののΔＢｍも１.８〜２.５％と低く、粉体およびこれを用いたテープともに耐酸化性に優れたものであった。
Examples 5 to 8 Magnetic powders were obtained by Examples 5 to 8 which were performed in the same manner as Examples 1 to 4 except that the conversion to α-iron oxide was not performed. Table 2 shows the magnetic powder characteristic values and tape evaluation values. The binding energy peaks of the powder were 529.2 eV in Example 5, 527.3 eV in Example 6, 525.4 eV in Example 7, and 526.9 eV in Example 8.
In Examples 5-8, as shown in Table 2, Δσs of the powder was as low as 4.7-7.0%, and ΔBm of this taped as described above was 1.8-2. As low as 5%, both the powder and the tape using the powder were excellent in oxidation resistance.
［実施例９〜１２］ アニール処理時の温度を表２中に記載の温度へ種々変更した以外は実施例１と同様に行った実施例９〜１２によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
粉体の結合エネルギーピークは実施例９では５３１.５ｅＶ、実施例１０では５２８.３ｅＶ、実施例１１では５３１.４ｅＶ、実施例１２では５３２.０ｅＶであった。
また、実施例９〜１２においては、表２の記載のとおり、粉体のΔσsは１０.３〜１４.７％とやや低く、これを前記のとおりテープ化したもののΔＢｍも３.２〜４.５％とやや低く、粉体およびこれを用いたテープともに耐酸化性にやや優れたものであった。
[Examples 9 to 12] Magnetic powders were obtained in Examples 9 to 12 which were performed in the same manner as in Example 1 except that the temperature during annealing was variously changed to the temperatures shown in Table 2. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
The binding energy peak of the powder was 531.5 eV in Example 9, 528.3 eV in Example 10, 531.4 eV in Example 11, and 532.0 eV in Example 12.
In Examples 9 to 12, as shown in Table 2, Δσs of the powder was slightly low at 10.3 to 14.7%, and ΔBm of this taped as described above was also 3.2 to 4 Slightly low at .5%, both the powder and the tape using the powder were somewhat excellent in oxidation resistance.
［実施例１３〜１６］ アニール処理時の時間を表２中に記載の時間へ種々変更した以外は実施例１と同様に行った実施例１３〜１６によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
粉体の結合エネルギーピークは実施例１３では５３１.８ｅＶ、実施例１４では５２９.４ｅＶ、実施例１５では５３０.２ｅＶ、実施例１６では５２７.２ｅＶであった。
また、実施例１３〜１６においては、表２の記載のとおり、粉体のΔσsは５.５〜１０.８％とやや低く、これを前記のとおりテープ化したもののΔＢｍも１.６〜７.６％とやや低く、粉体およびこれを用いたテープともに耐酸化性にやや優れたものであった。
[Examples 13 to 16] Magnetic powders were obtained in Examples 13 to 16 which were performed in the same manner as in Example 1 except that the annealing time was variously changed to the times shown in Table 2. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
The binding energy peaks of the powder were 531.8 eV in Example 13, 529.4 eV in Example 14, 530.2 eV in Example 15, and 527.2 eV in Example 16.
In Examples 13 to 16, as described in Table 2, Δσs of the powder was somewhat low, 5.5 to 10.8%, and ΔBm of the tape formed as described above was 1.6 to 7 It was slightly low at .6%, and both the powder and the tape using the powder were somewhat excellent in oxidation resistance.
［実施例１７］ アニール処理の活性ガスを一酸化炭素に変更した以外は実施例１と同様に行った実施例１７によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
この際の粉体の結合エネルギーピークは５２６.２ｅＶであり、粉体のΔσsは１０.４％とやや低く、これを前記のとおりテープ化したもののΔＢｍも６.４％とやや低く、粉体およびこれを用いたテープともに耐酸化性にやや優れたものであった。
[Example 17] Magnetic powder was obtained by Example 17 performed in the same manner as in Example 1 except that the active gas for the annealing treatment was changed to carbon monoxide. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
The binding energy peak of the powder at this time is 526.2 eV, the Δσs of the powder is slightly low at 10.4%, and the ΔBm of the powdered tape as described above is also slightly low at 6.4%. Both the tapes using the tape and the tape were slightly superior in oxidation resistance.
［実施例１８］ アニール処理の活性ガスをアセチレンに変更した以外は実施例１と同様に行った実施例１８によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
この際の粉体の結合エネルギーピークは５３１.３ｅＶであり、粉体のΔσsは１２.３％とやや低く、これを前記のとおりテープ化したもののΔＢｍも７.４％とやや低く、粉体およびこれを用いたテープともに耐酸化性にやや優れたものであった。
[Example 18] A magnetic powder was obtained by Example 18 performed in the same manner as in Example 1 except that the active gas for the annealing treatment was changed to acetylene. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
In this case, the binding energy peak of the powder is 531.3 eV, the Δσs of the powder is slightly low at 12.3%, and ΔBm of the tape formed as described above is also as low as 7.4%. Both the tapes using the tape and the tape were slightly superior in oxidation resistance.
［実施例１９］ アニール処理の活性ガスを一酸化炭素に変更した以外は実施例５と同様に行った実施例１９によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
この際の粉体の結合エネルギーピークは５２９.４ｅＶであり、粉体のΔσsは１１.５％とやや低く、これを前記のとおりテープ化したもののΔＢｍも７.９％とやや低く、粉体およびこれを用いたテープともに耐酸化性にやや優れたものであった。
[Example 19] A magnetic powder was obtained by Example 19 performed in the same manner as in Example 5 except that the active gas for the annealing treatment was changed to carbon monoxide. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
The binding energy peak of the powder at this time is 529.4 eV, the Δσs of the powder is slightly low as 11.5%, and the ΔBm of the tape formed as described above is also as low as 7.9%. Both the tapes using the tape and the tape were slightly superior in oxidation resistance.
［実施例２０］ アニール処理の活性ガスをアセチレンに変更した以外は実施例５と同様に行った実施例２０によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
この際の粉体の結合エネルギーピークは５３１.８ｅＶであり、粉体のΔσsは１２.８％とやや低く、これを前記のとおりテープ化したもののΔＢｍも７.６％とやや低く、粉体およびこれを用いたテープともに耐酸化性にやや優れたものであった。
[Example 20] Magnetic powder was obtained by Example 20 performed in the same manner as in Example 5 except that the active gas for the annealing treatment was changed to acetylene. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
The binding energy peak of the powder at this time is 531.8 eV, the powder Δσs is slightly low at 12.8%, and the ΔBm of the powdered tape as described above is also slightly low at 7.6%. Both the tapes using the tape and the tape were slightly superior in oxidation resistance.
［比較例１］ アニール処理を窒素中、３５０℃で３０分間実施した以外は実施例１と同様に行った比較例１によって磁性粉末を作成した。得られた磁性粉末の磁気特性、テープ評価値および物性値について表２に示し、結合エネルギーピークを図１に示す。
これによれば、粉体の結合エネルギーピークは５３２.５ｅＶにあって、Δσsは１７.３％と高く、これを前記のとおりテープ化したもののΔＢｍも８.９％と高く、粉体およびこれを用いたテープともに耐酸化性に劣るものであった。
[Comparative Example 1] A magnetic powder was prepared by Comparative Example 1 performed in the same manner as in Example 1 except that the annealing treatment was performed at 350 ° C for 30 minutes in nitrogen. The magnetic properties, tape evaluation values and physical properties of the obtained magnetic powder are shown in Table 2, and the binding energy peak is shown in FIG.
According to this, the binding energy peak of the powder is 532.5 eV, and Δσs is as high as 17.3%, and ΔBm of the tape as described above is also high as 8.9%. Both the tapes using the tape were inferior in oxidation resistance.
［比較例２〜４］ 核粒子の組成を表１、表２中の組成および物性値を有するものに変更した以外は比較例１と同様に行った比較例２〜４によって磁性粉末を得た。磁性粉末特性値、テープ評価値および物性値を表２に示す。
粉体の結合エネルギーピークは比較例２では５３４.５ｅＶ、比較例３では５３４.８ｅＶ、比較例４では５３３.７ｅＶであった。
また、比較例２〜４においては、表２の記載のとおり、粉体のΔσsは１５.８〜１７.３％と高く、これを前記のとおりテープ化したもののΔＢｍも８.１〜９.３％と高く、粉体およびこれを用いたテープともに耐酸化性に劣るものであった。
[Comparative Examples 2 to 4] Magnetic powders were obtained by Comparative Examples 2 to 4 which were carried out in the same manner as Comparative Example 1 except that the composition of the core particles was changed to those having the compositions and physical properties shown in Tables 1 and 2. . Table 2 shows the magnetic powder characteristic values, tape evaluation values, and physical property values.
The binding energy peak of the powder was 534.5 eV in Comparative Example 2, 534.8 eV in Comparative Example 3, and 533.7 eV in Comparative Example 4.
In Comparative Examples 2 to 4, as shown in Table 2, Δσs of the powder was as high as 15.8 to 17.3%, and ΔBm of this taped as described above was 8.1 to 9. As high as 3%, both the powder and the tape using the powder were inferior in oxidation resistance.
［比較例５〜８］ アニール工程以降を省略した以外は実施例１〜４と同様に行った比較例５〜８によって磁性粉末を得た。磁性粉末特性値、テープ評価値および物性値を表２に示す。
これによれば、粉体の結合エネルギーピークは比較例５では５３５.８ｅＶ、比較例６では５３５.４ｅＶ、比較例７では５３６.１ｅＶ、比較例８では５３５.２ｅＶにピークを有することが分かった。また、耐酸化性Δσsは比較例５で１９.３％、比較例６〜８でも１６.０〜２０.５％と高く、これを前記のとおりテープ化したもののΔＢｍも比較例５で８.７％であり、比較例６〜８でも６.２〜１０.３％と高く、粉体およびこれを用いたテープともに耐酸化性に劣るものであった。
[Comparative Examples 5 to 8] Magnetic powders were obtained by Comparative Examples 5 to 8 which were performed in the same manner as in Examples 1 to 4 except that the annealing process and the subsequent steps were omitted. Table 2 shows the magnetic powder characteristic values, tape evaluation values, and physical property values.
This shows that the binding energy peak of the powder has a peak at 535.8 eV in Comparative Example 5, 535.4 eV in Comparative Example 6, 536.1 eV in Comparative Example 7, and 535.2 eV in Comparative Example 8. It was. Further, the oxidation resistance Δσs was as high as 19.3% in Comparative Example 5 and as high as 16.0 to 20.5% in Comparative Examples 6-8, and ΔBm of this taped as described above was 8. It was 7%, and in Comparative Examples 6 to 8, it was as high as 6.2 to 10.3%. Both the powder and the tape using the same were inferior in oxidation resistance.
［比較例９〜１２］ 窒素中におけるアニール処理の温度を表２中に示したように変更した以外は比較例１と同様に行った比較例９〜１２によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
これによれば、粉体の結合エネルギーピークは比較例９では５３２.９ｅＶにあって、比較例１０では５３２.１ｅＶ、比較例１１では５３２.７ｅＶ、比較例１２では５３３.８ｅＶにピークを有することが分かった。また、耐酸化性Δσsは比較例９で１５.９％、比較例１０〜１２でも１５.４〜１６.２％と高く、これを前記のとおりテープ化したもののΔＢｍも比較例９で６.１％であり、比較例１０〜１２でも５.８〜７.３％とやや高く、粉体およびこれを用いたテープともに耐酸化性に若干劣るものであった。
[Comparative Examples 9-12] Magnetic powders were obtained by Comparative Examples 9-12, which were performed in the same manner as Comparative Example 1, except that the annealing temperature in nitrogen was changed as shown in Table 2. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
According to this, the binding energy peak of the powder is 532.9 eV in Comparative Example 9, and has a peak at 532.1 eV in Comparative Example 10, 532.7 eV in Comparative Example 11, and 533.8 eV in Comparative Example 12. I understood that. Further, the oxidation resistance Δσs was as high as 15.9% in Comparative Example 9 and 15.4 to 16.2% in Comparative Examples 10-12, and ΔBm of the tape obtained as described above was 6. It was 1%, and comparative examples 10 to 12 were slightly high at 5.8 to 7.3%. Both the powder and the tape using the same were slightly inferior in oxidation resistance.
［比較例１３〜１６］ α酸化鉄への変換（焼成）工程を経ずにオキシ水酸化鉄から直接還元処理を実施した後に、安定化処理を行い、その後に実施する窒素中におけるアニール処理の温度を表２中に示したように変更した以外は比較例１と同様に行った比較例１３〜１６によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
これによれば、粉体の結合エネルギーピークは比較例１３では５３５.６ｅＶにあって、比較例１４では５３３.４ｅＶ、比較例１５では５３４.８ｅＶ、比較例１６では５３５.４ｅＶにピークを有することが分かった。また、耐酸化性Δσsは比較例１３で１９.４％、比較例１４〜１６でも１６.４〜１８.６％と高く、これを前記のとおりテープ化したもののΔＢｍも比較例１３で９.８％であり、比較例１４〜１６でも７.２〜８.１％と高く、粉体およびこれを用いたテープともに耐酸化性に劣るものであった。
[Comparative Examples 13 to 16] After carrying out a reduction treatment directly from iron oxyhydroxide without going through a conversion (firing) step into α-iron oxide, a stabilization treatment is carried out, and then an annealing treatment in nitrogen is carried out. Magnetic powders were obtained by Comparative Examples 13 to 16 which were carried out in the same manner as Comparative Example 1 except that the temperature was changed as shown in Table 2. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
According to this, the binding energy peak of the powder is 535.6 eV in Comparative Example 13, and has a peak at 533.4 eV in Comparative Example 14, 534.8 eV in Comparative Example 15, and 535.4 eV in Comparative Example 16. I understood that. Further, the oxidation resistance Δσs was as high as 19.4% in Comparative Example 13 and 16.4 to 18.6% in Comparative Examples 14 to 16, and ΔBm of the tape formed as described above was 9. Even in Comparative Examples 14 to 16, it was as high as 7.2 to 8.1%. Both the powder and the tape using the same were inferior in oxidation resistance.
［比較例１７〜２０］ α酸化鉄への変換（焼成）工程を経ずにオキシ水酸化鉄から直接還元処理を実施した後に、安定化処理を行い、その後に実施する窒素中におけるアニール処理の温度、時間を表２中に示したように変更した以外は比較例１と同様に行った比較例１７〜２０によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
これによれば、粉体の結合エネルギーピークは比較例１７では５３４.２ｅＶにあって、比較例１８では５３２.９ｅＶ、比較例１９では５３５.８ｅＶ、比較例２０では５３５.３ｅＶにピークを有することが分かった。また、耐酸化性Δσsは比較例１７で１７.８％、比較例１８〜２０でも１５.８〜２３.２％と高く、これを前記のとおりテープ化したもののΔＢｍも比較例１７で７.６％であり、比較例１８〜２０でも５.７〜１１.３％と高く、粉体およびこれを用いたテープともに耐酸化性に劣るものであった。
[Comparative Examples 17 to 20] After carrying out a reduction treatment directly from iron oxyhydroxide without going through the conversion (firing) step to α-iron oxide, a stabilization treatment is carried out, and then an annealing treatment in nitrogen is carried out. Magnetic powders were obtained by Comparative Examples 17 to 20 which were carried out in the same manner as Comparative Example 1 except that the temperature and time were changed as shown in Table 2. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
According to this, the binding energy peak of the powder is 534.2 eV in Comparative Example 17, has a peak at 532.9 eV in Comparative Example 18, 535.8 eV in Comparative Example 19, and 535.3 eV in Comparative Example 20. I understood that. Further, the oxidation resistance Δσs was as high as 17.8% in Comparative Example 17 and as high as 15.8 to 23.2% in Comparative Examples 18 to 20, and ΔBm of the tape formed as described above was 7. It was 6%, and Comparative Examples 18-20 were as high as 5.7-11.3%, and both the powder and the tape using the same were inferior in oxidation resistance.
［比較例２１〜２４］ 窒素中におけるアニール処理の温度および時間を表２中に示したように変更した以外は比較例１と同様に行った比較例２１〜２４によって磁性粉末を得た。磁性粉末特性値、テープ評価値を表２にあわせて示す。
これによれば、粉体の結合エネルギーピークは比較例２１では５３５.９ｅＶにあって、比較例２２では５３４.８ｅＶ、比較例２３では５３６.７ｅＶ、比較例２４では５３７.０ｅＶにピークを有することが分かった。また、耐酸化性Δσsは比較例２１で１７.４％、比較例２２〜２４でも１５.９〜２０.３％と高く、これを前記のとおりテープ化したもののΔＢｍも比較例２１で７.４％であり、比較例２２〜２４でも５.９〜１２.９％と高く、粉体およびこれを用いたテープともに耐酸化性に劣るものであった。
[Comparative Examples 21 to 24] Magnetic powders were obtained by Comparative Examples 21 to 24 which were performed in the same manner as Comparative Example 1 except that the temperature and time of the annealing treatment in nitrogen were changed as shown in Table 2. The magnetic powder characteristic values and tape evaluation values are also shown in Table 2.
According to this, the binding energy peak of the powder is 535.9 eV in Comparative Example 21, has a peak at 534.8 eV in Comparative Example 22, 536.7 eV in Comparative Example 23, and 537.0 eV in Comparative Example 24. I understood that. Moreover, oxidation resistance (DELTA) (sigma) s is as high as 17.4% in the comparative example 21, and 15.9 to 20.3% in the comparative examples 22-24, and (DELTA) Bm of what was taped as above is also 7. It was 4%, and even in Comparative Examples 22 to 24, it was as high as 5.9 to 12.9%, and both the powder and the tape using the same were inferior in oxidation resistance.
図１における実施例１と比較例１の結合エネルギーピークに明らかな相違が観察され、これは酸化膜の形態が何らかの変化をうけているものといえる。また、このときの耐酸化性を示すΔσsに関しても顕著な改善が見られた。
実施例２、比較例２、比較例６の群、実施例３、比較例３、比較例７の群、実施例４、比較例４、比較例８の群に関しては、同一群内では同じ核粒子を使用しているので、粒子中に含有されるコバルト量により、本発明の効果が失われるか否かの検討ができる。その結果、いずれの場合においても、本発明の手法を用いて行うことにより耐酸化性が改善していることが明らかとなった。
A clear difference is observed in the binding energy peaks between Example 1 and Comparative Example 1 in FIG. 1, which can be said to be that the form of the oxide film has undergone some change. In addition, a significant improvement was observed with respect to Δσs indicating oxidation resistance at this time.
Regarding the groups of Example 2, Comparative Example 2, and Comparative Example 6, Example 3, Comparative Example 3, and Comparative Example 7, Group 4, Example 4, Comparative Example 4, and Comparative Example 8, the same nucleus within the same group Since the particles are used, it is possible to examine whether or not the effect of the present invention is lost depending on the amount of cobalt contained in the particles. As a result, in any case, it was revealed that the oxidation resistance was improved by using the method of the present invention.
また、実施例１〜４と実施例５〜８の比較により、焼成を施したときとそうでないとき、即ち還元開始時における粒子状態による相違を知ることができる。これより、還元開始物質としては、むしろヘマタイトよりはオキシ水酸化鉄を用いた方が、本発明の処理方法を適用するにあたり特性をより改善できることが分かる。 Moreover, the comparison with Examples 1-4 and Examples 5-8 can know the difference by the particle state at the time of baking when it does not, ie, at the time of starting reduction. From this, it can be seen that the use of iron oxyhydroxide as a reduction starting material rather than hematite can further improve the characteristics in applying the treatment method of the present invention.
実施例１と実施例１３〜１６の結果の比較により、還元雰囲気中でのアニール処理の時間による特性および耐酸化性に対する効果の相違がわかる。これより、処理時間は長ければ長いほど効果的であるとは限らず、適度な時間設定によって、より効果的に特性が改善することが分かる。 Comparison of the results of Example 1 and Examples 13 to 16 reveals the difference in the effect on the characteristics and oxidation resistance depending on the time of annealing treatment in a reducing atmosphere. From this, it can be seen that the longer the processing time, the more effective the effect, and the more effective the characteristics can be improved by setting an appropriate time.
実施例１と実施例１７、１８の比較により、使用する還元ガスの種類による効果の確認ができるようになっている。この結果から還元性ガスの種類により磁性粉末の特性に違いが生じることがわかり、還元性ガスの中でも水素ガスが最も適していることが分かる。 By comparing Example 1 with Examples 17 and 18, the effect of the type of reducing gas used can be confirmed. From this result, it can be seen that the characteristics of the magnetic powder differ depending on the type of reducing gas, and it is understood that hydrogen gas is most suitable among the reducing gases.
実施例１と実施例９〜１２の比較により、還元雰囲気下におけるアニール処理において還元を行う温度としてどの程度の温度が妥当かの検討を行うことができる。この結果から、温度はやや低めの温度で行うことが好ましく、さらには、３００〜４００℃の間で行うことが特に好ましいことが分かる。 By comparing Example 1 and Examples 9 to 12, it is possible to examine what temperature is appropriate as the temperature at which reduction is performed in the annealing treatment in a reducing atmosphere. From this result, it can be seen that the temperature is preferably slightly lower, and more preferably between 300-400 ° C.
比較例９〜２４は、アニール処理を窒素中で実施した場合のアニール条件による磁性粉末の特性の変動を示したもので、比較例９〜１２が出発原料をα―酸化鉄、比較例１３〜１６が出発原料をオキシ水酸化鉄とし、アニール処理の時間を一定とした上で温度をそれぞれ変化させたもの、比較例１７〜２０が出発原料をオキシ水酸化鉄、比較例２１〜２４が出発原料をα−酸化鉄とし、アニール処理の温度を一定とした上で時間をそれぞれ変化させたときの磁性粉末の特性の動きについて示したものになっている。これらと実施例１を比較すれば、アニール工程では、雰囲気は不活性ガスである窒素よりは水素を用いて弱還元する方が好ましいことが分かる。 Comparative Examples 9 to 24 show changes in the characteristics of the magnetic powder depending on the annealing conditions when the annealing treatment is performed in nitrogen. Comparative Examples 9 to 12 are α-iron oxide as a starting material, and Comparative Examples 13 to No. 16 was iron oxyhydroxide as a starting material, and the temperature was changed after keeping the annealing time constant, Comparative Examples 17 to 20 were iron oxyhydroxide as starting materials, and Comparative Examples 21 to 24 were starting This shows the behavior of the characteristics of the magnetic powder when the raw material is α-iron oxide and the annealing temperature is kept constant and the time is changed. Comparing these with Example 1, it can be seen that in the annealing process, it is preferable that the atmosphere be weakly reduced using hydrogen rather than nitrogen, which is an inert gas.
また、実施例で示しているとおり、通常の還元・酸化安定化処理の後に再度水素を系内に導入し、再度磁性粉末に対してアニール処理を施すことによって、本明細書に示したようなＸ線光電子分光法での特徴のある磁性粉末が得られ、かような磁性粉末は耐酸化性に優れていることが見いだせた。また、各磁気特性においても、公知の方法を使用して得られた磁性粉末の特性よりも優れた特性を有する磁性粉末を得ることができる。 In addition, as shown in the examples, hydrogen is again introduced into the system after the normal reduction / oxidation stabilization treatment, and the magnetic powder is annealed again, so that as shown in the present specification. A magnetic powder characteristic of X-ray photoelectron spectroscopy was obtained, and it was found that such a magnetic powder was excellent in oxidation resistance. Moreover, also in each magnetic characteristic, the magnetic powder which has the characteristic superior to the characteristic of the magnetic powder obtained using the well-known method can be obtained.
家庭用ＡＶ機器用テープ、データバックアップ用ストレージテープといった高容量化、高密度化、高画質化が求められる磁気記録媒体に適用できる。 The present invention can be applied to magnetic recording media that require high capacity, high density, and high image quality, such as home AV equipment tapes and data backup storage tapes.
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| LAPS | Cancellation because of no payment of annual fees |