JP5280661B2 - Method for producing metal magnetic powder - Google Patents
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- JP5280661B2 JP5280661B2 JP2007252450A JP2007252450A JP5280661B2 JP 5280661 B2 JP5280661 B2 JP 5280661B2 JP 2007252450 A JP2007252450 A JP 2007252450A JP 2007252450 A JP2007252450 A JP 2007252450A JP 5280661 B2 JP5280661 B2 JP 5280661B2
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本発明は、金属磁性粉末およびその製造方法に関し、特に、塗布型磁気記録媒体に使用される強磁性金属粉末およびその製造方法に関する。 The present invention relates to a metal magnetic powder and a method for producing the same, and more particularly to a ferromagnetic metal powder used for a coating type magnetic recording medium and a method for producing the same.
塗布型磁気記録媒体に使用される代表的な金属磁性粉末として、鉄を主成分として含有する鉄系磁性粉末がある。このような鉄系金属磁性粉末は、工業的には、オキシ水酸化鉄または酸化鉄を主体とした針状粉末に、形状保持のためにＳｉやＡｌなどを含有させるとともに、焼結防止のために希土類元素やアルカリ土類金属元素などを含有させて、焼成した後に還元することによって製造されている。このような鉄系金属磁性粉末を製造する従来の方法として、α−ＦｅＯＯＨにＮｉ、Ｃｏ、Ａｌ、Ｓｉおよび希土類元素の化合物を被着させ、非還元性雰囲気下で熱処理し、次いで還元性ガスで還元する方法（例えば、特許文献１参照）や、含水酸化鉄の粒子表面に希土類金属化合物やＡｌ化合物などを被着させた後、不活性ガス雰囲気において加熱脱水し、次いで還元性ガスで還元する方法（例えば、特許文献２参照）が知られている。 As a typical metal magnetic powder used for a coating type magnetic recording medium, there is an iron-based magnetic powder containing iron as a main component. Industrially, such iron-based metal magnetic powders contain needle-like powders mainly composed of iron oxyhydroxide or iron oxide to contain Si, Al, etc. in order to maintain the shape and prevent sintering. It is manufactured by adding a rare earth element, an alkaline earth metal element, or the like, firing, and then reducing. As a conventional method for producing such iron-based metal magnetic powder, α-FeOOH is coated with a compound of Ni, Co, Al, Si and a rare earth element, heat-treated in a non-reducing atmosphere, and then reducing gas. (See, for example, Patent Document 1) or after depositing rare earth metal compounds or Al compounds on the surface of hydrous iron oxide particles, followed by heat dehydration in an inert gas atmosphere and then reducing with a reducing gas There is a known method (for example, see Patent Document 2).
近年、塗布型磁気記録媒体などの磁気記録媒体では、大容量化に伴って記録密度を高めることが要求されており、磁気記録媒体の記録密度を高めるためには、磁性粉末の粒子体積を小さくすることが必要になる。 In recent years, magnetic recording media such as coating-type magnetic recording media have been required to increase the recording density as the capacity increases, and in order to increase the recording density of the magnetic recording medium, the particle volume of the magnetic powder is reduced. It becomes necessary to do.
しかし、磁性粉末を微粒子化すると、磁性粉末の粒子の形状を保持し難くなるため、形状保持のために添加するＳｉやＡｌなどの量や、焼結防止のために添加する希土類元素などの量を増加させることが必要になる。しかし、形状保持のために添加するＳｉやＡｌなどや、焼結防止のために添加する希土類元素などは、熱処理工程後には既に役割を終えており、何ら磁性に影響を及ぼすものではなく、粒子体積を大きくするだけであり、粒子性ノイズの低減のためには少ない方がよい。特に、磁性粉末の粒子の表層部に存在する希土類元素などや、ＳｉやＡｌなどの非磁性成分を除去して、粒子体積を小さくするのが望ましい。 However, when the magnetic powder is made into fine particles, it becomes difficult to maintain the shape of the magnetic powder particles. Therefore, the amount of Si or Al added to maintain the shape, the amount of rare earth elements added to prevent sintering, etc. Need to be increased. However, Si and Al added to maintain the shape, rare earth elements added to prevent sintering, etc. have already finished their roles after the heat treatment process and do not affect magnetism at all. It is only necessary to increase the volume, and it is better to reduce the particle noise. In particular, it is desirable to reduce the volume of the particles by removing rare earth elements, etc. present in the surface layer portion of the particles of the magnetic powder and nonmagnetic components such as Si and Al.
本出願人は、このような磁性粉末の粒子の表層部に存在する希土類元素などや、ＳｉやＡｌなどの非磁性成分を除去して、粒子体積を小さくするために、鉄または鉄とコバルトを主成分として含有する金属磁性粉末の表層部に存在する非磁性成分を溶出除去する方法を提案している（特願２００６−２６１５３１）。 In order to reduce the particle volume by removing rare earth elements present in the surface layer portion of such magnetic powder particles and nonmagnetic components such as Si and Al, the applicant of the present invention uses iron or iron and cobalt. A method of eluting and removing nonmagnetic components present in the surface layer portion of the metal magnetic powder contained as the main component has been proposed (Japanese Patent Application No. 2006-261531).
しかし、金属磁性粉末の表層部に存在する非磁性成分を溶出除去して、金属磁性粉末の粒子を微細化すると、粒子同士が凝集して凝集体を形成し易くなる。このような凝集体が大量に存在する金属磁性粉末を、塗布型磁気記録媒体の表面の磁性層を形成するために使用すると、個々の粒子の粒度分布を改善しても、より薄層になる磁性層を形成するための塗料に使用するには適さない。 However, when the nonmagnetic component present in the surface layer portion of the metal magnetic powder is eluted and removed to make the particles of the metal magnetic powder finer, the particles tend to aggregate to form an aggregate. When a metal magnetic powder having a large amount of such aggregates is used to form a magnetic layer on the surface of a coating type magnetic recording medium, a thin layer is obtained even if the particle size distribution of individual particles is improved. Not suitable for use in paints for forming magnetic layers.
したがって、本発明は、粒子を小さくしても粒子同士の凝集を防止することができる、金属磁性粉末およびその製造方法を提供することを目的とする。 Accordingly, an object of the present invention is to provide a metal magnetic powder and a method for producing the same, which can prevent aggregation of particles even when the particles are made smaller.
本発明者らは、上記課題を解決するために鋭意研究した結果、鉄または鉄とコバルトを主成分として含有し且つ非磁性成分を含有する金属磁性粉末の表層部に存在する非磁性成分を溶出除去するとともに、金属磁性粉末の表面に有機物を付着させることにより、金属磁性粉末の粒子を小さくしても粒子同士の凝集を防止することができることを見出し、本発明を完成するに至った。 As a result of diligent research to solve the above problems, the present inventors have eluted non-magnetic components present in the surface layer portion of metal magnetic powder containing iron or iron and cobalt as main components and containing non-magnetic components. It was found that by removing and attaching organic matter to the surface of the metal magnetic powder, the particles could be prevented from aggregating even if the particles of the metal magnetic powder were made smaller, and the present invention was completed.
すなわち、本発明による金属磁性粉末の製造方法は、鉄または鉄とコバルトを主成分として含有し且つ非磁性成分を含有する金属磁性粉末を製造する工程と、この金属磁性粉末の表層部の非磁性成分を溶出除去する工程と、表層部の非磁性成分を溶出除去した後の金属磁性粉末の表面に有機物を付着させる工程とを備えたことを特徴とする。 That is, the method for producing a metal magnetic powder according to the present invention comprises a step of producing a metal magnetic powder containing iron or iron and cobalt as main components and a nonmagnetic component, and a nonmagnetic property of the surface layer portion of the metal magnetic powder. A step of eluting and removing the components, and a step of attaching an organic substance to the surface of the metal magnetic powder after the nonmagnetic component of the surface layer portion is eluted and removed.
この金属磁性粉末の製造方法において、非磁性成分は、（イットリウムを含む）希土類元素、アルミニウムおよび珪素からなる群から選ばれる１種以上であるのが好ましい。また、非磁性成分を溶出除去する工程が、非磁性成分と錯体を形成し得る錯化剤を添加した溶液に、非磁性成分を含有する金属磁性粉末を添加して分散させた後、還元剤を添加し、浸出によって溶液中に非磁性成分を溶出除去する工程であるのが好ましい。また、金属磁性粉末の表面に有機物を付着させる工程は、非磁性成分を溶出除去する工程において使用した溶液中に、有機溶剤または高分子有機化合物を添加することによって、金属磁性粉末の表面に有機物を付着させる工程でもよいし、あるいは、非磁性成分を溶出除去する工程において使用した溶液から分離した金属磁性粉末に、有機溶剤または高分子有機化合物溶液を含浸させることによって、金属磁性粉末の表面に有機物を付着させる工程でもよい。これらの場合、有機溶剤または高分子有機化合物が、アルコール、エーテルおよびそれらの誘導体からなる群から選ばれる１種以上であるのが好ましい。さらに、有機物を付着させた金属磁性粉末の表面に酸化膜を形成する酸化処理工程を含むのが好ましく、酸化膜を形成した金属磁性粉末を還元処理した後に酸化処理する安定化処理工程を含むのが好ましい。 In this metal magnetic powder production method, the nonmagnetic component is preferably at least one selected from the group consisting of rare earth elements (including yttrium), aluminum and silicon. Further, the step of eluting and removing the nonmagnetic component comprises adding a metal magnetic powder containing the nonmagnetic component to a solution containing a complexing agent capable of forming a complex with the nonmagnetic component, and then dispersing the reducing agent. It is preferable that the nonmagnetic component is eluted and removed from the solution by leaching. In addition, the step of attaching the organic substance to the surface of the metal magnetic powder is performed by adding an organic solvent or a polymer organic compound to the solution used in the step of eluting and removing the non-magnetic component, thereby adding an organic substance to the surface of the metal magnetic powder. The surface of the metal magnetic powder may be applied by impregnating the metal magnetic powder separated from the solution used in the step of eluting and removing the nonmagnetic component with an organic solvent or a polymer solution of the organic compound. It may be a step of attaching an organic substance. In these cases, the organic solvent or the polymer organic compound is preferably at least one selected from the group consisting of alcohols, ethers and derivatives thereof. Furthermore, it is preferable to include an oxidation treatment step of forming an oxide film on the surface of the metal magnetic powder to which the organic matter is adhered, and a stabilization treatment step of oxidizing the metal magnetic powder having the oxide film formed thereon after the reduction treatment is included. Is preferred.
また、本発明による金属磁性粉末は、鉄または鉄とコバルトを主成分として含有するとともに、０．５〜４．０質量％の炭素を含有し、磁性成分の含有量に対する非磁性成分の含有量の割合が２０％以下であることを特徴とする。 In addition, the metal magnetic powder according to the present invention contains iron or iron and cobalt as main components and also contains 0.5 to 4.0% by mass of carbon, and the content of the nonmagnetic component with respect to the content of the magnetic component. The ratio is 20% or less.
この金属磁性粉末において、磁性成分が、鉄または鉄とコバルトであり、非磁性成分が、（イットリウムを含む）希土類元素、アルミニウムおよび珪素からなる群から選ばれる１種以上と、炭素を含むのが好ましい。また、金属磁性粉末の粒子の平均長軸長が１０〜５０ｎｍであるのが好ましい。 In this metal magnetic powder, the magnetic component is iron or iron and cobalt, the nonmagnetic component is one or more selected from the group consisting of rare earth elements (including yttrium), aluminum and silicon, and carbon. preferable. The average major axis length of the metal magnetic powder particles is preferably 10 to 50 nm.
本発明によれば、鉄または鉄とコバルトを主成分として含有し且つ非磁性成分を含有する金属磁性粉末の表層部に存在する非磁性成分を溶出除去するとともに、金属磁性粉末の表面に有機物を付着させることにより、金属磁性粉末の粒子を小さくしても粒子同士の凝集を防止することができる。 According to the present invention, the nonmagnetic component present in the surface layer portion of the metal magnetic powder containing iron or iron and cobalt as main components and containing the nonmagnetic component is eluted and removed, and an organic substance is applied to the surface of the metal magnetic powder. By making it adhere, even if it makes the particle | grains of metal magnetic powder small, aggregation of particle | grains can be prevented.
本発明による金属磁性粉末の製造方法の実施の形態は、形状保持や焼結防止のために非磁性成分が添加された原料粉末を焼成した後に還元して、鉄または鉄とコバルトを主成分として含有し且つ形状保持や焼結防止のために添加された非磁性成分を含有する金属磁性粉末を製造する金属磁性粉末製造工程と、この金属磁性粉末の表層部の非磁性成分を溶出除去する溶出処理工程と、表層部の非磁性成分を溶出除去した後の金属磁性粉末の表面に有機物を付着させる有機物処理工程と、有機物を付着させた金属磁性粉末の表面に酸化膜を形成する酸化処理工程と、酸化膜を形成した金属磁性粉末を還元処理した後に酸化処理する再還元・安定化処理工程とを備えている。以下、これらの工程について説明する。 In the embodiment of the method for producing a metal magnetic powder according to the present invention, the raw material powder to which a nonmagnetic component is added is sintered for shape retention and sintering prevention, and then reduced, and iron or iron and cobalt are the main components. Metal magnetic powder manufacturing process for manufacturing metal magnetic powder containing nonmagnetic components that are contained and added for shape retention and prevention of sintering, and elution that elutes and removes nonmagnetic components in the surface layer of this metal magnetic powder Treatment step, organic matter treatment step for attaching organic matter to the surface of metal magnetic powder after elution and removal of non-magnetic components on the surface layer portion, and oxidation treatment step for forming an oxide film on the surface of metal magnetic powder to which organic matter is attached And a re-reduction / stabilization treatment step in which the metal magnetic powder on which the oxide film is formed is subjected to a reduction treatment and then an oxidation treatment. Hereinafter, these steps will be described.
（金属磁性粉末製造工程）
形状保持や焼結防止のために非磁性成分が添加された原料粉末を焼成した後に還元して、鉄または鉄とコバルトを主成分として含有し且つ形状保持や焼結防止のために添加された非磁性成分を含有する金属磁性粉末を製造するまでの工程としては、一般的な金属磁性粉末の製造工程を採用することができる。例えば、コバルトおよび焼結防止のために添加した希土類元素などを含有するオキシ水酸化鉄を２５０〜７００℃で焼成して、α−Ｆｅ２Ｏ３などの鉄酸化物にした後、この鉄酸化物を気相還元によって加熱還元して、α−Ｆｅを主成分として含有し且つ希土類元素などの非磁性成分を含有する金属磁性粉末（中間製品としての金属磁性粉末）を得る。
(Metal magnetic powder manufacturing process)
Raw material powder with non-magnetic components added for shape retention and sintering prevention was reduced after firing, and contained iron or iron and cobalt as main components and added for shape retention and sintering prevention As a process until a metal magnetic powder containing a nonmagnetic component is manufactured, a general process for manufacturing a metal magnetic powder can be employed. For example, iron oxyhydroxide containing cobalt and rare earth elements added to prevent sintering is baked at 250 to 700 ° C. to form iron oxides such as α-Fe 2 O 3, and the iron oxidation The product is heated and reduced by vapor phase reduction to obtain a metal magnetic powder containing α-Fe as a main component and a nonmagnetic component such as a rare earth element (metal magnetic powder as an intermediate product).
（溶出処理工程）
このようにして得られた金属磁性粉末に含まれる希土類元素（イットリウムを含む）、アルミニウム（Ａｌ）および珪素（Ｓｉ）の少なくとも１種以上と錯体を形成し得る化合物（錯化剤）を溶解した溶液を処理液として用意する。この処理液は、室温付近の温度で調整することができる。錯化剤としては、無電解めっきにおいて錯化剤として通常使用されている薬品、例えば、酒石酸塩、クエン酸塩、リンゴ酸塩、乳酸塩などを使用することができる。錯化剤の濃度は、０.０１〜１０モル／Ｌ程度でよい。また、必要に応じて、ｐＨ緩衝効果がある物質、例えば、アンモニウム塩などを添加してもよい。
(Elution process)
A compound (complexing agent) capable of forming a complex with at least one of rare earth elements (including yttrium), aluminum (Al) and silicon (Si) contained in the metal magnetic powder thus obtained was dissolved. A solution is prepared as a processing solution. This treatment liquid can be adjusted at a temperature around room temperature. As the complexing agent, chemicals usually used as a complexing agent in electroless plating, such as tartrate, citrate, malate, lactate and the like can be used. The concentration of the complexing agent may be about 0.01 to 10 mol / L. Moreover, you may add the substance which has a pH buffer effect, for example, ammonium salt etc. as needed.
次に、この処理液に金属磁性粉末を添加する。金属磁性粉末の添加量は、多過ぎると反応が不均一になる可能性があるので、処理液１Ｌ当たり１〜１００ｇ程度であるのが好ましく、５〜５０ｇ程度であるのがさらに好ましい。また、液中の反応の均一性を維持するため、撹拌または強制分散（例えば、超音波分散など）を行うのが好ましい。 Next, a metal magnetic powder is added to the treatment liquid. If the addition amount of the metal magnetic powder is too large, the reaction may become non-uniform, so that it is preferably about 1 to 100 g, more preferably about 5 to 50 g, per liter of the treatment liquid. Further, in order to maintain the uniformity of the reaction in the liquid, it is preferable to perform stirring or forced dispersion (for example, ultrasonic dispersion).
処理液中に金属磁性粉末が均一に分散させた後、還元剤を添加する。この還元剤としては、ヒドラジン（Ｎ２Ｈ２）、リチウムアルミニウムハイドライド（ＬｉＡｌＨ４）、ナトリウムボロンハイドライド（ＮａＢＨ４）のような強還元剤を使用することができる。還元能力が弱い還元剤を使用すると、磁性元素の溶出が起こり易くなるので好ましくない。また、還元剤の濃度は、濃過ぎると非磁性成分の溶出効果が低下するので好ましくなく、一方、薄過ぎると磁性元素が溶出し易くなるので好ましくない。そのため、還元剤の濃度は、０.０１〜１０モル／Ｌにするのが好ましく、０.０５〜５モル／Ｌにするのがさらに好ましく、０.１〜５モル／Ｌにするのが最も好ましい。 After the metal magnetic powder is uniformly dispersed in the treatment liquid, a reducing agent is added. As this reducing agent, strong reducing agents such as hydrazine (N 2 H 2 ), lithium aluminum hydride (LiAlH 4 ), and sodium boron hydride (NaBH 4 ) can be used. Use of a reducing agent having a weak reducing ability is not preferable because elution of a magnetic element is likely to occur. On the other hand, if the concentration of the reducing agent is too high, the elution effect of the non-magnetic component is lowered, which is not preferable. Therefore, the concentration of the reducing agent is preferably 0.01 to 10 mol / L, more preferably 0.05 to 5 mol / L, and most preferably 0.1 to 5 mol / L. preferable.
この還元剤を添加した後、液温を１０〜５０℃、好ましくは１５〜４０℃に保持しながら、１０〜３００分間浸出操作を行う。この浸出操作によって処理液中に非磁性成分が溶出し、金属磁性粉末の粒子中における磁性元素の量が相対的に上昇する。なお、この反応は、不活性ガス雰囲気において行うのが好ましい。 After adding this reducing agent, a leaching operation is performed for 10 to 300 minutes while maintaining the liquid temperature at 10 to 50 ° C., preferably 15 to 40 ° C. By this leaching operation, the nonmagnetic component is eluted in the treatment liquid, and the amount of the magnetic element in the particles of the metal magnetic powder is relatively increased. This reaction is preferably performed in an inert gas atmosphere.
（有機物処理工程）
次に、溶出処理した金属磁性粉末に有機物を付着させる有機物処理工程を行う。この有機物処理工程として、溶出処理に使用した液に有機溶剤や高分子有機化合物を直接投入してもよいし、溶出処理液から分離した金属磁性粉末に有機溶剤や高分子有機化合物溶液を含浸させてもよい。この有機物処理工程によって、金属磁性粉末に炭素成分を含有させるので、金属磁性粉末に有機物を均一に付着させるために、攪拌または強制分散（例えば、超音波分散など）を行うのが好ましい。
(Organic treatment process)
Next, an organic substance treatment step is performed in which an organic substance is attached to the eluted magnetic metal powder. As the organic matter treatment step, an organic solvent or a polymer organic compound may be directly added to the liquid used for the elution treatment, or the metal magnetic powder separated from the elution treatment liquid is impregnated with the organic solvent or the polymer organic compound solution. May be. Since the carbon component is contained in the metal magnetic powder through this organic substance treatment step, it is preferable to perform stirring or forced dispersion (for example, ultrasonic dispersion) in order to uniformly attach the organic substance to the metal magnetic powder.
この有機物処理工程に使用する有機化合物としては、メタノールやエタノールなどのアルコール類またはその誘導体、ジメチルエーテルやジエチルエーテルなどのエーテル類またはその誘導体を使用するのが好ましい。 As the organic compound used in this organic substance treatment step, alcohols such as methanol and ethanol or derivatives thereof, ethers such as dimethyl ether and diethyl ether or derivatives thereof are preferably used.
（酸化処理工程）
次に、必要に応じて、有機物処理した金属磁性粉末の粒子の表面に酸化膜を形成する酸化処理工程を行う。この酸化処理工程は、有機物処理に使用した液に酸化物を投入して湿式法で酸化処理する工程でもよいし、有機物処理液から分離して抽出した金属磁性粉末を乾式法で酸化処理する工程でもよい。
(Oxidation process)
Next, if necessary, an oxidation treatment step of forming an oxide film on the surface of the particles of the metal magnetic powder treated with organic matter is performed. This oxidation treatment step may be a step in which an oxide is added to a liquid used for organic matter treatment and oxidation treatment is performed by a wet method, or a metal magnetic powder separated and extracted from an organic treatment liquid is oxidized by a dry method. But you can.
（再還元・安定化処理工程）
次に、必要に応じて、酸化処理した金属磁性粉末に再度還元処理を施し、その後、再度酸化雰囲気に曝す安定化処理を施す。この再還元・安定化処理工程によって先端部が丸みを帯びた粒子が得られ易くなるので好ましい。再還元工程は、水素ガスなどの還元雰囲気下において熱処理することによって行うことができる。熱処理温度は、１５０℃以上であるのが好ましいが、高温になり過ぎると粒子間焼結が起こり易くなるので、３５０℃以下にする必要があり、３００℃以下にするのが好ましい。また、安定化処理は、酸化性ガス雰囲気において熱処理することによって行うことができる。この場合も、温度が高過ぎると焼結が生じ易いので、約１５０〜３５０℃で行うのが好ましい。
(Re-reduction / stabilization process)
Next, if necessary, the oxidized magnetic metal powder is subjected to reduction treatment again, and then subjected to stabilization treatment that is again exposed to an oxidizing atmosphere. This re-reduction / stabilization treatment step is preferable because particles having a rounded tip are easily obtained. The re-reduction step can be performed by heat treatment in a reducing atmosphere such as hydrogen gas. The heat treatment temperature is preferably 150 ° C. or higher. However, if the temperature is too high, inter-particle sintering is likely to occur. Therefore, the heat treatment temperature needs to be 350 ° C. or lower, and preferably 300 ° C. or lower. The stabilization treatment can be performed by heat treatment in an oxidizing gas atmosphere. In this case as well, sintering is likely to occur if the temperature is too high, so it is preferable to carry out at about 150 to 350 ° C.
このように、本発明による金属磁性粉末の製造方法の実施の形態は、金属磁性粉末の表層部に存在する（焼結防止剤のために添加した）希土類元素や（形状保持のために添加した）ＡｌやＳｉのような直接磁気特性への関与が薄い非磁性成分を選択的に溶出除去する工程と、金属磁性粒子の表面に炭素化合物由来の被覆層を形成する工程とを備えているので、個々の粒子の分散を保持し易い金属磁性粉末を製造することができる。 As described above, the embodiment of the method for producing the metal magnetic powder according to the present invention includes the rare earth element (added for the sintering inhibitor) present in the surface layer portion of the metal magnetic powder (added for maintaining the shape). ) Because it includes a step of selectively eluting and removing nonmagnetic components that are not directly involved in direct magnetic properties such as Al and Si, and a step of forming a coating layer derived from a carbon compound on the surface of metal magnetic particles. A metal magnetic powder that can easily maintain dispersion of individual particles can be produced.
上述した本発明による金属磁性粉末の製造方法の実施の形態により製造された金属磁性粉末は、鉄または鉄とコバルトを主成分とする金属磁性相を有する粒子からなる金属磁性粉末である。すなわち、金属磁性相を構成する磁性元素（例えば、鉄、コバルト、ニッケル）のうち、鉄または鉄とコバルトの合計の原子割合が５０％以上の金属磁性粉末である。この金属磁性粉末の表面には酸化膜が形成されており、鉄（Ｆｅ）とコバルト（Ｃｏ）を主成分として含有する金属磁性粉末では、酸化膜と金属磁性相を含む金属磁性粉末の粒子全体に存在する元素のモル比として「Ｃｏ含有量（ａｔ％）／Ｆｅ含有量（ａｔ％）×１００」で表される、Ｆｅに対するＣｏの原子割合（以下「Ｃｏ／Ｆｅ原子比」という）が、０〜５０ａｔ％であるのが好ましく、５〜４５ａｔ％であるのがさらに好ましく、１０〜４０ａｔ％であるのが最も好ましい。このような範囲であれば、安定した磁気特性が得られ易く、耐候性も良好になる。なお、酸化膜として鉄酸化物が検出されるが、その他の元素の酸化物が同時に存在してもよい。 The metal magnetic powder produced by the embodiment of the method for producing metal magnetic powder according to the present invention described above is a metal magnetic powder composed of particles having a metal magnetic phase mainly composed of iron or iron and cobalt. That is, among magnetic elements (for example, iron, cobalt, nickel) constituting the metal magnetic phase, it is a metal magnetic powder in which the total atomic ratio of iron or iron and cobalt is 50% or more. An oxide film is formed on the surface of the metal magnetic powder. In the metal magnetic powder containing iron (Fe) and cobalt (Co) as main components, the entire metal magnetic powder particles including the oxide film and the metal magnetic phase are used. The atomic ratio of Co to Fe (hereinafter referred to as “Co / Fe atomic ratio”) expressed as “Co content (at%) / Fe content (at%) × 100” as the molar ratio of the elements present in 0 to 50 at% is preferable, 5 to 45 at% is more preferable, and 10 to 40 at% is most preferable. Within such a range, stable magnetic characteristics can be easily obtained and weather resistance is also improved. Although iron oxide is detected as the oxide film, oxides of other elements may be present at the same time.
また、金属磁性粉末製造工程では、焼結防止のために（イットリウム（Ｙ）を含む）希土類元素（Ｒ）、Ａｌ、Ｓｉなどの非磁性成分が添加されているが、これらの非磁性成分は、溶出処理工程において除去されているので、（Ｒ＋Ｓｉ＋Ａｌ）／（Ｆｅ＋Ｃｏ）原子比が、２０ａｔ％以下になり、好ましくは１５ａｔ％以下、さらに好ましくは１３ａｔ％以下、最も好ましくは１２ａｔ％以下にすることができる。このように非磁性成分を除去することによって、従来の微粉化された金属磁性粉末と比べて、粒子体積が小さい割に飽和磁化が大きい粉末を得ることができる。 In addition, in the magnetic metal powder manufacturing process, non-magnetic components such as rare earth elements (R), Al, and Si (including yttrium (Y)) are added to prevent sintering. Since it is removed in the elution treatment step, the (R + Si + Al) / (Fe + Co) atomic ratio is 20 at% or less, preferably 15 at% or less, more preferably 13 at% or less, and most preferably 12 at% or less. Can do. By removing the nonmagnetic component in this way, it is possible to obtain a powder having a large saturation magnetization for a small particle volume as compared with a conventional finely divided metal magnetic powder.
また、上述した本発明による金属磁性粉末の製造方法の実施の形態により製造された金属磁性粉末には、有機物処理工程において有機物による表面被覆処理によって生じた炭素化合物成分が存在している。一般に、有機物処理を行わない金属磁性粉末には０.１質量％以下の炭素分が存在しているが、このように炭素分の含有量が少ないと、金属磁性粉末の個々の粒子の分散を保持するには不十分である。一方、炭素化合物は基本的には非磁性成分であるので、炭素化合物の被着量が多過ぎると、磁気特性を劣化させ、溶出処理工程において非磁性成分を除去した効果が損なわれるので好ましくない。そのため、金属磁性粉末中の炭素化合物として炭素の量は、０.５〜４.０質量％であるのが好ましく、１.０〜３.５質量％であるのがさらに好ましく、１.０〜３.０質量％であるのが最も好ましい。 In addition, the metal magnetic powder produced by the above-described embodiment of the method for producing metal magnetic powder according to the present invention contains a carbon compound component produced by surface coating treatment with an organic substance in the organic substance treatment step. In general, the metal magnetic powder not subjected to the organic treatment has a carbon content of 0.1% by mass or less. If the carbon content is so small, the dispersion of the individual particles of the metal magnetic powder is reduced. Insufficient to hold. On the other hand, since carbon compounds are basically non-magnetic components, if the amount of carbon compound deposited is too large, the magnetic properties are deteriorated and the effect of removing the non-magnetic components in the elution process is impaired, which is not preferable. . Therefore, the amount of carbon as the carbon compound in the metal magnetic powder is preferably 0.5 to 4.0% by mass, more preferably 1.0 to 3.5% by mass, and 1.0 to 1.0%. Most preferably, it is 3.0 mass%.
また、金属磁性粉末の粒子サイズについては、平均長軸長が１０〜５０ｎｍであるのが好ましく、１０〜４０ｎｍであるのがさらに好ましく、１０〜３５ｎｍであるのが最も好ましい。平均長軸長が５０ｎｍを超えると、粒子体積が大きくなってしまい、磁気記録の高記録密度化に十分対応することが難しくなる。 In addition, regarding the particle size of the metal magnetic powder, the average major axis length is preferably 10 to 50 nm, more preferably 10 to 40 nm, and most preferably 10 to 35 nm. When the average major axis length exceeds 50 nm, the particle volume becomes large, and it becomes difficult to sufficiently cope with the increase in recording density of magnetic recording.
上述した本発明による金属磁性粉末の製造方法の実施の形態により製造された金属磁性粉末は、重層塗布型磁気記録媒体の磁性層に使用することができる。重層塗布型磁気記録媒体は、ベースフィルムの上に、下層として非磁性層を有し、その上に上層として磁性層を有するが、金属磁性粉末は、上層の磁性層を形成するための塗料中に配合させて使用することができる。 The metal magnetic powder produced by the embodiment of the method for producing metal magnetic powder according to the present invention described above can be used for the magnetic layer of the multilayer coating type magnetic recording medium. The multilayer coating type magnetic recording medium has a nonmagnetic layer as a lower layer on a base film and a magnetic layer as an upper layer on the base film, but the metal magnetic powder is contained in a paint for forming an upper magnetic layer. Can be used in combination.
なお、上層および下層のいずれの塗料も、各材料を所定組成となるような割合で配合し、ニーダーやサンドグラインダーを用いて混練・分散させる方法により調合することができる。ベースフィルムへの塗料の塗布は、下層が湿潤なうちに可及的に速やかに上層の磁性層を塗布する、所謂ウエット・オン・ウエット方式で行うことが好ましい。 It should be noted that both the upper layer paint and the lower layer paint can be blended by a method in which the respective materials are blended at a ratio such that a predetermined composition is obtained and kneaded and dispersed using a kneader or a sand grinder. The coating is preferably applied to the base film by a so-called wet-on-wet method in which the upper magnetic layer is applied as quickly as possible while the lower layer is wet.
重層塗布型磁気記録媒体では、ベースフィルムとして、例えば、ポリエチレンテレフタラート、ポリエチレンナフタレートなどのポリエステル類、ポリオレフィン類、セルローストリアセテート、ポリカーボネイト、ポリアミド、ポリイミド、ポリアミドイミド、ポリスルフォンアラミド、芳香族ポリアミドなどの樹脂フィルムを使用することができる。また、下層の非磁性層用塗料として、例えば、非磁性粉末（ＤＯＷＡエレクトロニクス（株）製のα−酸化鉄、平均長軸粒子径８０ｎｍ）８５質量部と、カーボンブラック２０質量部と、アルミナ３質量部と、塩化ビニル樹脂（日本ゼオン（株）製の塩化ビニル系バインダーＭＲ−１１０）１５質量部と、ポリウレタン樹脂（東洋紡（株）製のポリウレタン樹脂ＵＲ−８２００）１５質量部と、メチルエチルケトン１９０質量部と、シクロヘキサノン８０質量部と、トルエン１１０質量部とからなる組成の非磁性塗料を使用することができる。さらに、上層の磁性層用塗料として、例えば、金属磁性粉末１００質量部と、カーボンブラック５質量部と、アルミナ３質量部と、塩化ビニル樹脂（日本ゼオン（株）製のＭＲ−１１０）１５質量部と、ポリウレタン樹脂（東洋紡（株）製のＵＲ−８２００）１５質量部と、ステアリン酸１質量部と、アセチルアセトン１質量部と、メチルエチルケトン１９０質量部と、シクロヘキサノン８０質量部と、トルエン１１０質量部とからなる組成の磁性塗料を使用することができる。 In the multilayer coating type magnetic recording medium, as a base film, for example, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins, cellulose triacetate, polycarbonate, polyamide, polyimide, polyamideimide, polysulfone aramid, aromatic polyamide, etc. A resin film can be used. Examples of the coating material for the lower nonmagnetic layer include, for example, 85 parts by mass of nonmagnetic powder (α-iron oxide manufactured by DOWA Electronics Co., Ltd., average major axis particle size of 80 nm), 20 parts by mass of carbon black, and alumina 3 15 parts by mass of vinyl chloride resin (vinyl chloride binder MR-110 manufactured by Nippon Zeon Co., Ltd.), 15 parts by mass of polyurethane resin (polyurethane resin UR-8200 manufactured by Toyobo Co., Ltd.), and methyl ethyl ketone 190 A nonmagnetic paint having a composition composed of part by mass, 80 parts by mass of cyclohexanone, and 110 parts by mass of toluene can be used. Further, as the magnetic layer coating for the upper layer, for example, 100 parts by mass of metal magnetic powder, 5 parts by mass of carbon black, 3 parts by mass of alumina, and 15 parts by mass of vinyl chloride resin (MR-110 manufactured by Nippon Zeon Co., Ltd.) Parts, 15 parts by mass of polyurethane resin (UR-8200 manufactured by Toyobo Co., Ltd.), 1 part by mass of stearic acid, 1 part by mass of acetylacetone, 190 parts by mass of methyl ethyl ketone, 80 parts by mass of cyclohexanone, and 110 parts by mass of toluene A magnetic coating composition having the following composition can be used.
以下、本発明による金属磁性粉末およびその製造方法の実施例について詳細に説明する。 Examples of the magnetic metal powder and the method for producing the same according to the present invention will be described in detail below.
［実施例１］
まず、５０００ｍＬのビーカーに純水３０００ｍＬを入れた後、温調機で３０℃に維持しながら、０.０３モル／Ｌの硫酸コバルト（特級試薬）溶液と０.１５モル／Ｌの硫酸第一鉄（特級試薬）水溶液をＣｏ：Ｆｅ＝１：４の混合割合になるように混合した。この混合溶液５００ｍＬに、Ｆｅ＋Ｃｏに対して炭酸が３当量になる量の顆粒状の炭酸ナトリウムを直接添加し、液中温度が４０±５℃の範囲を超えないように調整しながら、炭酸鉄を主体とする懸濁液を作製した。この懸濁液を９０分間熟成させた後、Ｆｅイオンの酸化率が２０％になるように調整した量の空気を５０ｍＬ／分の流量で添加して核晶を形成させ、６０℃まで昇温させ、純酸素を５０ｍＬ／分の流量で通気して６０分間酸化を継続した。その後、純酸素を窒素に切り替えて、３０分間程度熟成した。
[Example 1]
First, after adding 3000 mL of pure water to a 5000 mL beaker, maintaining a temperature controller at 30 ° C., a 0.03 mol / L cobalt sulfate (special grade reagent) solution and 0.15 mol / L sulfuric acid first An aqueous solution of iron (special grade reagent) was mixed so as to have a mixing ratio of Co: Fe = 1: 4. To 500 mL of this mixed solution, granulated sodium carbonate in an amount of 3 equivalents of Fe + Co was directly added, and the temperature in the liquid was adjusted so as not to exceed the range of 40 ± 5 ° C. A main suspension was prepared. After aging this suspension for 90 minutes, air adjusted to an oxidation rate of Fe ions of 20% was added at a flow rate of 50 mL / min to form nuclei, and the temperature was raised to 60 ° C. Then, pure oxygen was aerated at a flow rate of 50 mL / min and oxidation was continued for 60 minutes. Thereafter, the pure oxygen was switched to nitrogen and aged for about 30 minutes.
次に、液温を４０℃まで降温させて温度が安定した後、１.０質量％のＡｌの硫酸アルミニウム水溶液を５.０ｇ／分の添加速度で２０分間添加し続けてオキシ水酸化鉄を成長させた。その後、純酸素を５０ｍＬ／分の流量で流し続け、酸化を完結させた。なお、酸化の終点の確認は、上澄み液を少量分取し、ヘキサシアノ酸鉄カリウム溶液を添加して、液色が変化しないことを確認することによって行った。 Next, after the liquid temperature was lowered to 40 ° C. and stabilized, 1.0 mass% Al aluminum sulfate aqueous solution was continuously added at an addition rate of 5.0 g / min for 20 minutes, and iron oxyhydroxide was added. Grown up. Thereafter, pure oxygen was kept flowing at a flow rate of 50 mL / min to complete the oxidation. The end point of the oxidation was confirmed by taking a small amount of the supernatant and adding an iron potassium hexacyanoate solution to confirm that the liquid color did not change.
次に、酸化終了後の液に（イットリウムとして２.０質量％含有する）酸化イットリウムの硫酸水溶液３００ｇを添加して、Ａｌを固溶させ、イットリウムが表面に被着したオキシ水酸化鉄の粉末（ケーキ）を得た。 Next, 300 g of an aqueous solution of sulfuric acid of yttrium oxide (containing 2.0% by mass as yttrium) is added to the liquid after completion of oxidation to dissolve Al, and iron oxyhydroxide powder with yttrium deposited on the surface (Cake) was obtained.
このオキシ水酸化鉄のケーキを濾過し、水洗した後、１３０℃で６時間乾燥させ、オキシ水酸化鉄の乾燥固形物を得た。この乾燥固形物１０ｇをバケットに入れ、水の流量として１.０ｇ／分で水蒸気を添加しながら大気中において４００℃で焼成し、α−酸化鉄（ヘマタイト）を主成分とする鉄系酸化物を得た。 The iron oxyhydroxide cake was filtered, washed with water, and then dried at 130 ° C. for 6 hours to obtain a dried solid product of iron oxyhydroxide. 10 g of this dried solid substance is put in a bucket, and fired at 400 ° C. in the air while adding water vapor at a flow rate of 1.0 g / min, and an iron-based oxide containing α-iron oxide (hematite) as a main component. Got.
このα−酸化鉄を主成分とする鉄系酸化物を通気可能なバケット内に投入した後、バケットを貫通型還元炉内に装入し、水素ガスを４０Ｌ／分の流量で通気しながら、水の流量として１.０ｇ／分で水蒸気を添加しながら、４００℃で３０分間焼成させて還元処理を行った。この還元処理が終了した後、水蒸気の供給を停止し、水素雰囲気下において昇温速度１０℃／分で６００℃まで昇温させた。その後、水の流量として１.０ｇ／分で水蒸気を添加しながら６０分間高温還元処理を行い、鉄系合金粉末（中間製品としての金属磁性粉末）を得た。 After putting this iron-based oxide containing α-iron oxide as a main component into a bucket that can be ventilated, the bucket was charged into a through-type reduction furnace, and hydrogen gas was vented at a flow rate of 40 L / min. While adding water vapor at a water flow rate of 1.0 g / min, baking was performed at 400 ° C. for 30 minutes for reduction treatment. After the reduction treatment was completed, the supply of water vapor was stopped, and the temperature was raised to 600 ° C. at a temperature rising rate of 10 ° C./min in a hydrogen atmosphere. Thereafter, a high temperature reduction treatment was performed for 60 minutes while adding water vapor at a water flow rate of 1.0 g / min to obtain an iron-based alloy powder (metal magnetic powder as an intermediate product).
次に、この粉末の溶出処理を行うために使用する処理液として、純水９００ｍＬに対して、錯化剤として酒石酸ナトリウムを０.０５モル／Ｌ、緩衝剤として硫酸アンモニウムを０.１モル／Ｌになるように混合し、ＮＨ３でｐＨ＝９に調整した処理液を用意した。この処理液に還元処理後の粉末１０ｇを投入して３０℃に保持した後、還元剤として水素化ホウ素ナトリウムを０.３モル／Ｌになるように添加し、３０℃で３０分間撹拌しながら熟成させ、スラリーを得た。このスラリーを固液分離し、固形分を水洗し、濾過して濾過物を得た。 Next, as a treatment liquid used for the elution treatment of the powder, 0.05 mol / L of sodium tartrate as a complexing agent and 0.1 mol / L of ammonium sulfate as a buffering agent are used with respect to 900 mL of pure water. Then, a treatment liquid adjusted to pH = 9 with NH 3 was prepared. 10 g of the powder after the reduction treatment was added to this treatment liquid and kept at 30 ° C., then sodium borohydride was added as a reducing agent to 0.3 mol / L, and the mixture was stirred at 30 ° C. for 30 minutes. Aging was performed to obtain a slurry. This slurry was subjected to solid-liquid separation, and the solid content was washed with water and filtered to obtain a filtrate.
この濾過物を２.０質量％のポリビニルアルコール水溶液（分子量１８０００〜２７０００）に入れ、２５℃で３０分間攪拌して有機物処理を行い、得られたスラリーから固形分を回収した。 This filtrate was put into a 2.0% by mass aqueous polyvinyl alcohol solution (molecular weight: 18000-27000), stirred at 25 ° C. for 30 minutes for organic treatment, and solid content was recovered from the resulting slurry.
次に、回収した固形分を通気可能なバケット内に入れた後、バケットを貫通型還元炉内に装入し、５０Ｌ／分の流量で窒素を導入しながら９０℃で乾燥させて粉末を得た。その後、窒素と純酸素をそれぞれ５０Ｌ／分および４００ｍＬ／分の流量で混合したガスを炉内に添加し、水の流量として１.０ｇ／分で水蒸気を添加しながら、水蒸気と酸素と窒素の混合雰囲気中において、粉末の表面に酸化膜を形成し、表面の酸化による発熱が抑制された段階で純酸素の流量を徐々に増加することによって、混合雰囲気中における酸素濃度を上昇させ、最終的な純酸素の流量を２.０Ｌ／分にした。なお、炉内に導入されるガスの総量は、窒素の流量を調整することによってほぼ一定に保たれるようにし、この酸化処理は、約９０℃に維持される雰囲気下において１時間行った。 Next, after putting the collected solid content in a bucket that can be ventilated, the bucket is placed in a through-type reduction furnace and dried at 90 ° C. while introducing nitrogen at a flow rate of 50 L / min to obtain a powder. It was. Thereafter, a gas in which nitrogen and pure oxygen are mixed at a flow rate of 50 L / min and 400 mL / min, respectively, is added to the furnace, and water vapor is added at a flow rate of 1.0 g / min. In the mixed atmosphere, an oxide film is formed on the surface of the powder, and the oxygen concentration in the mixed atmosphere is increased and finally increased by gradually increasing the flow rate of pure oxygen at the stage where heat generation due to surface oxidation is suppressed. The flow rate of pure oxygen was 2.0 L / min. The total amount of gas introduced into the furnace was kept substantially constant by adjusting the flow rate of nitrogen, and this oxidation treatment was performed for 1 hour in an atmosphere maintained at about 90 ° C.
次に、表面に酸化膜を形成した粉末を２５０℃の水素雰囲気下に３０分間曝すことによって再還元処理を行った後、上記の酸化処理と同様の方法によって安定化処理を行った。 Next, after performing re-reduction treatment by exposing the powder having an oxide film formed on the surface in a hydrogen atmosphere at 250 ° C. for 30 minutes, stabilization treatment was performed by the same method as the oxidation treatment described above.
このようにして得られた金属磁性粉末（最終製品としての金属磁性粉末）について、組成分析、炭素含有量および磁気特性などの測定を行った。粉末の組成は、金属磁性相と酸化膜を含む粒子全体の質量分析を行うことによって求めた。なお、Ｃｏ、Ａｌおよび希土類元素（Ｙを含む）の定量は、日本ジャーレルアッシュ株式会社製の高周波誘導プラズマ発光分析装置ＩＣＰ（ＩＲＩＳ／ＡＰ）を使用し、Ｆｅの定量は、平沼産業株式会社製の平沼自動滴定装置（ＣＯＮＴＩＭＥ−９８０型）を使用して行った。また、粉末中の炭素含有量は、堀場製作所製のＣ／Ｓ同時分析装置ＥＭＩＡ−２２０Ｖを使用して測定した。さらに、粉末の磁気特性は、東英工業株式会社製のＶＳＭ装置（ＶＳＭ−７Ｐ）を使用して外部磁場１０ｋＯｅ（７９５.８ｋＡ／ｍ）で測定した。その結果を表２および表３に示す。なお、本実施例において得られた金属磁性粉末の製造条件を表１に示し、表２の「非磁性／磁性」は、磁性成分（Ｆｅ、Ｃｏ）に対する非磁性成分（Ａｌ、Ｙ、Ｃ）の割合（百分率）を示している。 The thus obtained metal magnetic powder (metal magnetic powder as a final product) was measured for composition analysis, carbon content, magnetic properties, and the like. The composition of the powder was determined by performing mass analysis of the entire particle including the metal magnetic phase and the oxide film. Co, Al and rare earth elements (including Y) were quantified using a high frequency induction plasma emission analyzer ICP (IRIS / AP) manufactured by Nippon Jarrel Ash Co., and Fe was quantified by Hiranuma Sangyo Co., Ltd. This was carried out using a Hiranuma automatic titrator (CONTIME-980 type). Further, the carbon content in the powder was measured using a C / S simultaneous analyzer EMIA-220V manufactured by Horiba. Furthermore, the magnetic properties of the powder were measured with an external magnetic field of 10 kOe (795.8 kA / m) using a VSM apparatus (VSM-7P) manufactured by Toei Industry Co., Ltd. The results are shown in Tables 2 and 3. The production conditions of the metal magnetic powder obtained in this example are shown in Table 1, and “Nonmagnetic / Magnetic” in Table 2 is a nonmagnetic component (Al, Y, C) relative to a magnetic component (Fe, Co). The percentage (percentage) is shown.
表２に示すように、金属磁性粉末中のＦｅ、Ｃｏ、Ａｌ、Ｙ、Ｃの含有量は、それぞれ５７．５６質量％、１２．４質量％、１．８１質量％、４．９８質量％、２．４６質量％であり、非磁性／磁性は１３．２％であった。また、表３に示すように、金属磁性粉末の保磁力は１８８１Ｏｅ（１４９．８ｋＡ／ｍ）、飽和磁化は１２３．６Ａｍ２／ｋｇであった。 As shown in Table 2, the contents of Fe, Co, Al, Y, and C in the metal magnetic powder were 57.56% by mass, 12.4% by mass, 1.81% by mass, and 4.98% by mass, respectively. It was 2.46% by mass, and nonmagnetic / magnetic was 13.2%. Further, as shown in Table 3, the coercive force of the metal magnetic powder was 1881 Oe (149.8 kA / m), and the saturation magnetization was 123.6 Am 2 / kg.
次に、得られた金属磁性粉末（最終製品としての金属磁性粉末）０.３５ｇを秤量して（内径４５ｍｍ、深さ１３ｍｍの）ポットに入れ、蓋を開けた状態で１０分間放置した後、マイクロピペットでビヒクル（東洋紡製の塩化ビニル系樹脂ＭＲ−１１０（２２質量％）と、シクロヘキサノン（３８.７質量％）と、アセチルアセトン（０.３質量％）と、ステアリン酸−ｎ−ブチル（０.３質量％）と、メチルエチルケトン（３８.７質量％）の混合溶液）０.７ｍＬを添加し、その直後にスチールボール（２φ）３０ｇ、ナイロンボール（８φ）１０個をポットに加えて、蓋を閉じた状態で１０分間静置した。その後、ポットを遠心式ボールミル（ＦＲＩＴＳＨ Ｐ−６）にセットし、ゆっくりと回転数を上げて６００ｒｐｍに調整し、６０分間分散させた。遠心式ボールミルを停止した後、ポットを取り出し、予めメチルエチルケトンとトルエンを１：１で混合した調整液１.８ｍＬをマイクロピペットで添加した。その後、再びポットを遠心式ボールミルにセットし、６００ｒｐｍで５分間分散させ、磁性塗料を作製した。 Next, 0.35 g of the obtained metal magnetic powder (metal magnetic powder as a final product) was weighed and placed in a pot (inner diameter 45 mm, depth 13 mm) and left for 10 minutes with the lid open, A vehicle with a micropipette (vinyl chloride resin MR-110 (22% by mass), cyclohexanone (38.7% by mass), acetylacetone (0.3% by mass), stearic acid-n-butyl (0% by Toyobo) .3 mass%) and methyl ethyl ketone (38.7 mass%) mixed solution (0.7 mL) are added. Immediately thereafter, 30 g of steel balls (2φ) and 10 nylon balls (8φ) are added to the pot, Was allowed to stand for 10 minutes in a closed state. Thereafter, the pot was set on a centrifugal ball mill (FRITSH P-6), and the number of rotations was slowly increased to 600 rpm and dispersed for 60 minutes. After stopping the centrifugal ball mill, the pot was taken out, and 1.8 mL of a preliminarily mixed solution of methyl ethyl ketone and toluene at 1: 1 was added with a micropipette. Thereafter, the pot was set again on the centrifugal ball mill, and dispersed at 600 rpm for 5 minutes to produce a magnetic paint.
次に、ポットの蓋を開けてナイロンボールを取り除き、スチールボールごと磁性塗料をアプリケータ（５５０μｍ）に入れ、ベースフィルム（東レ株式会社製のポリエチレンフィルム１５Ｃ−Ｂ５００、膜厚１５μｍ）上に磁性塗料を塗布し、迅速に５.５ｋＧの配向器のコイル中心に置いて磁場配向させた後、乾燥させて磁気テープを作製した。なお、ここでは金属磁性粉末の効果をより鮮明に確認するため、非磁性層を設けず、磁性層単層のテープを作製した。
Next, the pot lid is opened, the nylon balls are removed, the steel ball and the magnetic paint are placed in the applicator (550 μm), and the magnetic paint is applied on the base film (polyethylene film 15C-B500 manufactured by Toray Industries, Inc.,
このようにして作製した媒体としての磁気テープについて、東英工業株式会社製のＶＳＭ装置（ＶＳＭ−７Ｐ）を使用して磁気測定を行い、保磁力Ｈｃ、保磁力分布ＳＦＤ、角形比ＳＱ、配向比ＯＲを求めた。その結果を表４に示す。 The magnetic tape as the medium thus produced was subjected to magnetic measurement using a VSM device (VSM-7P) manufactured by Toei Kogyo Co., Ltd., and coercive force Hc, coercive force distribution SFD, squareness ratio SQ, orientation The ratio OR was determined. The results are shown in Table 4.
表４に示すように、磁気テープの保磁力Ｈｃは２５３３Ｏｅ（２０１．７ｋＡ／ｍ）、保磁力分布ＳＦＤは０．７０、角形比ＳＱは０．７８８、配向比ＯＲは２．３２であった。 As shown in Table 4, the coercive force Hc of the magnetic tape was 2533 Oe (201.7 kA / m), the coercive force distribution SFD was 0.70, the squareness ratio SQ was 0.788, and the orientation ratio OR was 2.32. .
［実施例２〜７］
有機物処理において使用したポリビニルアルコール水溶液の代わりに、実施例２では２.０質量％のアセチレングリコール系分散剤水溶液（日信化学工業株式会社製のＥｘｐ．４０３６）、実施例３では１０質量％のビニルピロリドン水溶液（分子量１１１.１４）、実施例４では２５質量％のエチレングリコール水溶液（分子量６２.０７）、実施例５では２５質量％のジエチレングリコール水溶液（分子量１０６.１２）、実施例６では２５質量％のポリエチレングリコール２００水溶液（分子量１９０〜２００）、実施例７ではエタノールを使用した以外は、実施例１と同様の処理により、金属磁性粉末および磁気テープを作製し、実施例１と同様の測定を行った。その製造条件および結果を表１〜表４に示す。
[Examples 2 to 7]
Instead of the aqueous polyvinyl alcohol solution used in the organic substance treatment, in Example 2, a 2.0% by mass acetylene glycol-based dispersant aqueous solution (Exp. 4036 manufactured by Nissin Chemical Industry Co., Ltd.), in Example 3, 10% by mass Vinylpyrrolidone aqueous solution (molecular weight 111.14), 25 mass% ethylene glycol aqueous solution (molecular weight 62.07) in Example 4, 25 mass% diethylene glycol aqueous solution (molecular weight 106.12) in Example 5, 25 in Example 6 A metal magnetic powder and a magnetic tape were prepared in the same manner as in Example 1 except that ethanol was used in mass% of polyethylene glycol 200 aqueous solution (molecular weight 190 to 200) and Example 7 except that ethanol was used. Measurements were made. The production conditions and results are shown in Tables 1 to 4.
［実施例８〜１０］
有機物処理において使用したポリビニルアルコール水溶液の代わりに２５質量％のエチレングリコール水溶液（分子量６２.０７）を使用し、回収した固形分を乾燥させる前に、メタノール（実施例８）、アセトン（実施例９）、イソプロピルアルコール（実施例１０）中で攪拌して後処理を行った以外は、実施例１と同様の処理により、金属磁性粉末および磁気テープを作製し、実施例１と同様の測定を行った。その製造条件および結果を表１〜表４に示す。
[Examples 8 to 10]
A 25% by mass ethylene glycol aqueous solution (molecular weight 62.07) was used in place of the polyvinyl alcohol aqueous solution used in the organic treatment, and methanol (Example 8) and acetone (Example 9) were dried before the collected solid was dried. ) A metal magnetic powder and a magnetic tape were prepared by the same treatment as in Example 1 except that the post-treatment was performed by stirring in isopropyl alcohol (Example 10), and the same measurement as in Example 1 was performed. It was. The production conditions and results are shown in Tables 1 to 4.
［比較例１、２］
有機物処理において使用したポリビニルアルコール水溶液の代わりに、比較例１では２.０質量％のポリビニルピロリドンＫ３０水溶液（分子量４００００）、比較例２では２５質量％ポリエチレングリコール４００水溶液（分子量３８０〜４００）を使用した以外は、実施例１と同様の処理により、金属磁性粉末および磁気テープを作製し、実施例１と同様の測定を行った。その製造条件および結果を表１〜表４に示す。
[Comparative Examples 1 and 2]
Instead of the polyvinyl alcohol aqueous solution used in the organic treatment, Comparative Example 1 uses a 2.0% by weight polyvinylpyrrolidone K30 aqueous solution (molecular weight 40000), and Comparative Example 2 uses a 25% by weight polyethylene glycol 400 aqueous solution (molecular weight 380 to 400). Except for the above, a metal magnetic powder and a magnetic tape were produced by the same treatment as in Example 1, and the same measurement as in Example 1 was performed. The production conditions and results are shown in Tables 1 to 4.
［比較例３］
溶出処理と有機物処理を行わなかった以外は、実施例１と同様の処理により、金属磁性粉末および磁気テープを作製し、実施例１と同様の測定を行った。その製造条件および結果を表１〜表４に示す。
[Comparative Example 3]
A metal magnetic powder and a magnetic tape were produced by the same treatment as in Example 1 except that the elution treatment and the organic matter treatment were not performed, and the same measurement as in Example 1 was performed. The production conditions and results are shown in Tables 1 to 4.
［比較例４］
有機物処理を行わなかった以外は、実施例１と同様の処理により、金属磁性粉末および磁気テープを作製し、実施例１と同様の測定を行った。その製造条件および結果を表１〜表４に示す。
[Comparative Example 4]
A metal magnetic powder and a magnetic tape were produced by the same treatment as in Example 1 except that the organic matter treatment was not performed, and the same measurement as in Example 1 was performed. The production conditions and results are shown in Tables 1 to 4.
また、実施例１〜１０および比較例１〜４で得られた金属磁性粉末の炭素含有量と、保磁力Ｈｃ、飽和磁化、磁気テープの保磁力分布ＳＦＤなどの各特性との関係を図１〜図３に示し、非磁性成分／磁性成分と各特性との関係を図４〜図６に示す。 Further, the relationship between the carbon content of the metal magnetic powders obtained in Examples 1 to 10 and Comparative Examples 1 to 4 and respective characteristics such as the coercive force Hc, the saturation magnetization, and the coercive force distribution SFD of the magnetic tape is shown in FIG. To FIG. 3, and the relationship between the nonmagnetic component / magnetic component and each characteristic is shown in FIGS.
図１〜図３に示すように、金属磁性粉末中の炭素含有量が４.０質量％を超える領域では、各特性が飽和または低下している。この領域では、有機物処理による効果が飽和していると考えられ、過剰の炭素分が磁気特性を悪くする方向に働いている。また、炭素含有量が０.５質量％未満の領域では、磁気記録に重要な特性である保磁力Ｈｃを始め、各特性が悪化する傾向が見られる。また、炭素含有量が５.０質量％を超える領域では、各特性間のバランスが悪くなる。例えば、金属磁性粉末の磁気特性が実施例１〜１０と同等である比較例２でも、媒体の保磁力分布が悪化し、実施例１〜１０のような金属磁性粉末と媒体のバランスがとれていないことがわかる。 As shown in FIGS. 1 to 3, each characteristic is saturated or lowered in a region where the carbon content in the metal magnetic powder exceeds 4.0 mass%. In this region, it is considered that the effect of organic matter treatment is saturated, and excess carbon works in the direction of deteriorating magnetic properties. Also, in the region where the carbon content is less than 0.5 mass%, each characteristic tends to deteriorate, including the coercive force Hc which is an important characteristic for magnetic recording. Moreover, in the area | region where carbon content exceeds 5.0 mass%, the balance between each characteristic will worsen. For example, even in Comparative Example 2 in which the magnetic properties of the metal magnetic powder are equivalent to those of Examples 1 to 10, the coercive force distribution of the medium deteriorates, and the metal magnetic powder and the medium as in Examples 1 to 10 are balanced. I understand that there is no.
また、実施例１で得られた金属磁性粉末の粒子の３０，０００倍と１７４，０００倍の透過型電子顕微鏡（ＴＥＭ）写真をそれぞれ図７および図８に示し、比較例３で得られた金属磁性粉末の粒子の３０，０００倍と１７４，０００倍のＴＥＭ写真をそれぞれ図９および図１０に示す。比較例３で得られた金属磁性粉末の粒子のＴＥＭ写真には、焼結によると考えられる粒子集団（数十個の粒子の塊）が所々に観察されるのに対し、実施例１で得られた金属磁性粉末の粒子のＴＥＭ写真には、そのような粒子集団が殆ど観察されないので、実施例１で得られた金属磁性粉末では、このような良好な分散性が配向性を向上させるのに働いていると考えられ、粒子の独立性が担保できる。 Further, transmission electron microscope (TEM) photographs of 30,000 times and 174,000 times the particles of the metal magnetic powder obtained in Example 1 are shown in FIGS. 7 and 8, respectively, and obtained in Comparative Example 3. FIGS. 9 and 10 show TEM photographs of 30,000 times and 174,000 times the metal magnetic powder particles, respectively. In the TEM photograph of the particles of the metal magnetic powder obtained in Comparative Example 3, a particle population (several tens of particles) considered to be due to sintering is observed in some places, whereas it is obtained in Example 1. Since such a population of particles is hardly observed in the TEM photograph of the particles of the obtained metal magnetic powder, such good dispersibility improves the orientation in the metal magnetic powder obtained in Example 1. The independence of the particles can be guaranteed.
また、実施例５、７および比較例３で得られた金属磁性粉末の粒子のＸ線回折図を図１１に示す。得られた回折線をＪＣＰＤＳ（Ｊｏｉｎｔ Ｃｏｍｍｉｔｔｅｅ ｏｎ Ｐｏｗｄｅｒ Ｄｅｆｆｒａｃｔｉｏｎ Ｓｔａｎｄａｒｄｓ）で確認したところ、いずれのピークもＦｅのみを示す回折線になり、ＦｅとＣは炭化鉄のような化合物に変化していないことが確認された。 Moreover, the X-ray-diffraction figure of the particle | grains of the metal magnetic powder obtained in Examples 5 and 7 and Comparative Example 3 is shown in FIG. When the obtained diffraction lines were confirmed by JCPDS (Joint Committee on Powder Deflection Standards), all the peaks were diffraction lines showing only Fe, and Fe and C were not changed to compounds such as iron carbide. confirmed.
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| JP5781276B2 (en) | 2010-05-12 | 2015-09-16 | ジ・アリゾナ・ボード・オブ・リージェンツ・オン・ビハーフ・オブ・ザ・ユニバーシティ・オブ・アリゾナＴｈｅ Ａｒｉｚｏｎａ Ｂｏａｒｄ Ｏｆ Ｒｅｇｅｎｔｓ Ｏｎ Ｂｅｈａｌｆ Ｏｆ Ｔｈｅ Ｕｎｉｖｅｒｓｉｔｙ Ｏｆ Ａｒｉｚｏｎａ | Method for producing metal magnetic powder |
| JP5577851B2 (en) * | 2010-05-28 | 2014-08-27 | セイコーエプソン株式会社 | Pretreatment liquid, printing method and printed matter |
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| JPS5816001A (en) * | 1981-07-17 | 1983-01-29 | Fuji Photo Film Co Ltd | Production of ferromagnetic powder consisting essentially of iron |
| JPH0643601B2 (en) * | 1985-06-12 | 1994-06-08 | 戸田工業株式会社 | Method for producing metallic iron particle powder or alloy magnetic particle powder mainly composed of iron |
| JPH06279803A (en) * | 1993-03-29 | 1994-10-04 | Kanto Denka Kogyo Co Ltd | Metallic powder for magnetic recording and production thereof |
| JP4358016B2 (en) * | 2004-03-31 | 2009-11-04 | 明久 井上 | Iron-based metallic glass alloy |
| JP2006291257A (en) * | 2005-04-07 | 2006-10-26 | Sumitomo Metal Mining Co Ltd | Rare earth-transition metal-nitrogen based magnetic powder, and method for producing the same |
| JP4758858B2 (en) * | 2006-03-28 | 2011-08-31 | Ｄｏｗａエレクトロニクス株式会社 | Metallic magnetic powder for magnetic recording medium and method for producing the same |
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