JP5712594B2 - Hexagonal ferrite particles for magnetic recording media - Google Patents
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Description
本発明は、磁気記録媒体用六方晶フェライト粒子粉末に関するものであり、詳しくは、平均板面径が１０〜３０ｎｍ、粉体ＳＦＤが１．５以下であり、一般式ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）で表される、磁気記録媒体のノイズ低減に効果的な六方晶フェライト粒子粉末に関するものである。 The present invention relates to hexagonal ferrite particles for magnetic recording medium, particularly, an average plate surface diameter of 10 to 30 nm, powder SFD is 1.5 or less, the general formula AFe 12-x / 2- The present invention relates to a hexagonal ferrite particle powder represented by 2y / 3 Ti x Al y O 19 (A: one or more elements selected from Ba, Sr, and Ca) that is effective in reducing noise in magnetic recording media. .
磁気記録技術は、従来、オーディオ用、ビデオ用、コンピューター用等をはじめとしてさまざまな分野で幅広く用いられている。近年、機器の小型軽量化、記録の長時間化及び記録容量の増大等が求められており、記録媒体に対しては、記録密度のより一層の向上が望まれている。 Conventionally, magnetic recording technology has been widely used in various fields including audio, video, and computer. In recent years, there has been a demand for smaller and lighter devices, longer recording time, increased recording capacity, and the like, and further improvement in recording density is desired for recording media.
従来の磁気記録媒体に対してより高密度記録を行うためには、高いＣ／Ｎ比が必要であり、ノイズ（Ｎ）が低く、再生出力（Ｃ）が高いことが求められている。近年では、これまで用いられていた誘導型磁気ヘッドに替わり、磁気抵抗型ヘッド（ＭＲヘッド）や巨大磁気抵抗型ヘッド（ＧＭＲヘッド）等の高感度ヘッドが開発されており、これらは誘導型磁気ヘッドに比べて再生出力が得られやすいことから、高いＣ／Ｎ比を得るためには、出力を上げるよりもノイズを低減する方が重要となってきている。 In order to perform high-density recording on a conventional magnetic recording medium, a high C / N ratio is required, noise (N) is low, and reproduction output (C) is required to be high. In recent years, high-sensitivity heads such as magnetoresistive heads (MR heads) and giant magnetoresistive heads (GMR heads) have been developed in place of the inductive magnetic heads used so far. Since it is easy to obtain a reproduction output as compared with the head, in order to obtain a high C / N ratio, it is more important to reduce the noise than to increase the output.
磁気記録媒体のノイズは、粒子性ノイズと磁気記録媒体の表面性に起因して発生する表面性ノイズに大別される。粒子性ノイズの場合、粒子サイズの影響が大きく、微粒子であるほどノイズ低減に有利であることから、磁気記録媒体に用いる磁性粒子粉末の粒子サイズはできるだけ小さいことが必要となる。 The noise of the magnetic recording medium is roughly classified into particulate noise and surface noise generated due to the surface property of the magnetic recording medium. In the case of particulate noise, the influence of the particle size is large, and the finer the particle, the better the noise reduction. Therefore, the particle size of the magnetic particle powder used for the magnetic recording medium needs to be as small as possible.
一般に、微粒子、且つ、高保磁力値を有する磁性粒子粉末としては、鉄を主成分とする金属磁性粒子粉末及び六方晶フェライト粒子粉末等が知られており、六方晶フェライト粒子粉末は針状の金属磁性粒子粉末に比べ短波長領域で高い出力が得られるという特徴があり、再生にＭＲヘッドやＧＭＲヘッドを用いた高密度記録の磁気記録媒体用磁性粉末として非常に有望である。 Generally, as magnetic particles having fine particles and a high coercive force value, metal magnetic particle powders mainly composed of iron, hexagonal ferrite particle powders, and the like are known, and hexagonal ferrite particle powders are acicular metal. Compared with magnetic particle powder, it has a feature that a high output can be obtained in a short wavelength region, and is very promising as a magnetic powder for high-density recording magnetic recording media using an MR head or GMR head for reproduction.
しかしながら、六方晶フェライト粒子粉末は、一般に、粒子形状が板状であるため粒子同士がスタッキングしやすく、そのため、１個１個の粒子は微細化されているにもかかわらず挙動粒子体積が大きくなるため、ノイズ低減効果が得られ難いという問題を有している。 However, the hexagonal ferrite particle powder generally has a plate shape, so that the particles are easy to stack with each other. Therefore, the behavioral particle volume becomes large even though each particle is miniaturized. Therefore, there is a problem that it is difficult to obtain a noise reduction effect.
また、六方晶フェライト粒子粉末に磁性不純物（例えばγ−Ｆｅ２Ｏ３やＣｏスピネルフェライト等）が存在することにより、保磁力分布ＳＦＤ（Ｓｗｉｔｃｈｉｎｇ Ｆｉｅｌｄ Ｄｉｓｔｒｉｂｕｔｉｏｎ）が拡大するため、ノイズ低減が困難となることから、磁性不純物の存在しない六方晶フェライト粒子粉末が求められている。 Further, the presence of magnetic impurities (for example, γ-Fe 2 O 3 , Co spinel ferrite, etc.) in the hexagonal ferrite particle powder expands the coercive force distribution SFD (Switching Field Distribution), making it difficult to reduce noise. Therefore, hexagonal ferrite particle powder free from magnetic impurities is demanded.
これまでに、六方晶フェライト粒子粉末の配向性向上、スタッキング防止を目的として、板状比が１〜２の六方晶フェライト粒子粉末（特許文献１乃至特許文献４）等が知られている。 To date, hexagonal ferrite particle powders having a plate ratio of 1 to 2 (Patent Documents 1 to 4) and the like are known for the purpose of improving the orientation of the hexagonal ferrite particle powder and preventing stacking.
前出特許文献１乃至特許文献４には、六方晶フェライト粒子粉末の板状比を１〜２とすることで、六方晶フェライト粒子粉末のスタッキングを防止し、これを用いて得られる磁気記録媒体のノイズを低減して出力を向上させることが記載されているが、六方晶フェライト粒子粉末の磁性不純物を低減させて粉体ＳＦＤを改善することについては考慮されておらず、後出比較例に示す通り、六方晶フェライト粒子を構成する鉄の置換元素としてＣｏを用いた場合には、磁性不純物が生成するため、粉体ＳＦＤが拡大し、磁気記録媒体のノイズが高くなるため、優れた出力特性を得ることが困難である。 In the aforementioned Patent Documents 1 to 4, the plate ratio of the hexagonal ferrite particle powder is set to 1 to 2, thereby preventing stacking of the hexagonal ferrite particle powder, and a magnetic recording medium obtained by using this However, no consideration is given to improving the powder SFD by reducing the magnetic impurities in the hexagonal ferrite particles, and this will be described in a later comparative example. As shown, when Co is used as a substitution element for iron constituting the hexagonal ferrite particles, magnetic impurities are generated, so that the powder SFD expands and the noise of the magnetic recording medium increases, resulting in excellent output. It is difficult to obtain characteristics.
そこで、本発明は、六方晶フェライト粒子粉末の平均板面径が１０〜３０ｎｍであり、一般式ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）で表される、磁気記録媒体のノイズ低減に効果的な六方晶フェライト粒子粉末を得ることを技術的課題とする。 Accordingly, the present invention has an average plate surface diameter 10~30nm hexagonal ferrite particles, the formula AFe 12-x / 2-2y / 3 Ti x Al y O 19 (A: Ba, Sr, and Ca It is a technical problem to obtain hexagonal ferrite particle powder that is effective for reducing noise in a magnetic recording medium represented by one or more selected elements.
前記技術的課題は、次の通りの本発明によって達成できる。 The technical problem can be achieved by the present invention as follows.
即ち、本発明は、下記一般式で表されるマグネトプランバイト型フェライト粒子粉末からなり、平均板面径が１０〜３０ｎｍ、粉体ＳＦＤが１．５以下であることを特徴とする磁気記録媒体用六方晶フェライト粒子粉末である（本発明１）。
ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９
（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）
（ｘ：０．０５〜３、ｙ：０．１〜３）
That is, the present invention is a magnetic recording medium comprising a magnetoplumbite type ferrite particle powder represented by the following general formula, having an average plate surface diameter of 10 to 30 nm and a powder SFD of 1.5 or less. Hexagonal ferrite particle powder for use (Invention 1).
AFe 12-x / 2-2y / 3 Ti x Al y O 19
(A: one or more elements selected from Ba, Sr and Ca)
(X: 0.05~3, y: 0.1 ~3)
また、本発明は、板状比が２．０未満である本発明１記載の磁気記録媒体用六方晶フェライト粒子粉末である（本発明２）。 Further, the present invention is the hexagonal ferrite particle powder for magnetic recording media according to the present invention 1 having a plate ratio of less than 2.0 (the present invention 2).
また、本発明は、保磁力（Ｈｃ）が１１９．４ｋＡ／ｍ以上であることを特徴とする本発明１又は本発明２に記載の磁気記録媒体用六方晶フェライト粒子粉末である（本発明３）。 Further, the present invention is the hexagonal ferrite particle powder for magnetic recording media according to the present invention 1 or 2, wherein the coercive force (Hc) is 119.4 kA / m or more (Invention 3). ).
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、平均板面径が１０〜３０ｎｍ、粉体ＳＦＤが１．５以下であり、一般式ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）から成ることによって磁性不純物が生成しにくく、磁気記録媒体のノイズをより低減できるため、高密度磁気記録媒体の磁性粒子粉末として好適である。 The hexagonal ferrite particle powder for magnetic recording media according to the present invention has an average plate surface diameter of 10 to 30 nm, a powder SFD of 1.5 or less, and a general formula AFe 12-x / 2-2y / 3 Ti x Al. The magnetic particles of the high-density magnetic recording medium are made of y O 19 (A: one or more elements selected from Ba, Sr, and Ca), so that magnetic impurities are hardly generated and noise of the magnetic recording medium can be further reduced. Suitable as a powder.
本発明の構成をより詳しく説明すれば、次の通りである。 The configuration of the present invention will be described in more detail as follows.
先ず、本発明に係る磁気記録媒体用六方晶フェライト粒子粉末について述べる。 First, the hexagonal ferrite particle powder for magnetic recording media according to the present invention will be described.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、下記一般式で表されるマグネトプランバイト型フェライト粒子粉末からなり、平均板面径が１０〜３０ｎｍ、粉体ＳＦＤが１．５以下であることを特徴とする。
ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９
（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）
（ｘ：０．０５〜３、ｙ：０．１〜３）
The hexagonal ferrite particle powder for magnetic recording media according to the present invention comprises a magnetoplumbite type ferrite particle powder represented by the following general formula, having an average plate surface diameter of 10 to 30 nm and a powder SFD of 1.5 or less. It is characterized by being.
AFe 12-x / 2-2y / 3 Ti x Al y O 19
(A: one or more elements selected from Ba, Sr and Ca)
(X: 0.05~3, y: 0.1 ~3)
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、ＡＦｅ１２Ｏ１９で表されるマグネトプランバイト型フェライト粒子粉末のＦｅの置換元素としてＴｉ及びＡｌを用いることで、板状比を２．０未満とすることができると共に、磁性不純物の生成を抑制できるので、粉体ＳＦＤを改善することができる。また、粒子サイズのより一層の低減を考慮すれば、置換元素としては、Ｔｉ及びＡｌを用いることが好ましい。 The hexagonal ferrite particle powder for a magnetic recording medium according to the present invention uses Ti and Al as substitution elements for Fe in the magnetoplumbite type ferrite particle powder represented by AFe 12 O 19 so that the plate ratio is 2. Since it can be less than 0 and the generation of magnetic impurities can be suppressed, the powder SFD can be improved. In consideration of further reduction of the particle size, it is preferable to use Ti and Al as substitution elements.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の上記組成式におけるｘは、０．０５〜３の範囲であることが好ましく、より好ましくは０．５５〜２．５、更により好ましくは０．６０〜２である。ｘの値が０．０５未満の場合には、粒子サイズの分布が悪くなり、粉体ＳＦＤが拡大するため好ましくない。ｘの値が３を超える場合には、保磁力Ｈｃが低下するため好ましくない。また、上記組成におけるｙは、好ましくは０．１〜３の範囲であり、更に好ましくは０．１５〜２である。ｙの値が０、即ち置換元素としてＡｌを用いなくても磁気記録媒体用六方晶フェライト粒子粉末を得ることはできるが、置換元素としてＡｌを用いることにより、粒子サイズの分布及び粉体ＳＦＤをより改善することができると共に、粒子サイズをより一層低減することが可能となる。ｙの値が３を超える場合には、飽和磁化値σｓが低下するため好ましくない。 In the above composition formula of the hexagonal ferrite particles for magnetic recording media according to the present invention, x is preferably in the range of 0.05 to 3, more preferably 0.55 to 2.5, and even more preferably 0. .60-2. When the value of x is less than 0.05, the particle size distribution becomes poor and the powder SFD is enlarged, which is not preferable. When the value of x exceeds 3, the coercive force Hc decreases, which is not preferable. Further, y in the composition, the good Mashiku in the range of 0.1 to 3, more preferably from 0.15 to 2. the value of y is 0, that although it is possible to obtain a hexagonal ferrite particles for magnetic recording medium without using Al as substitution elements, the use of Al as the substituent element, particle size distribution and powder SFD As well as the particle size can be further reduced. When the value of y exceeds 3, the saturation magnetization value σs decreases, which is not preferable.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、一般式ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９で表されるが、Ｆｅの一部が更にＣｏ、Ｎｉ、Ｚｎ、Ｍｎ、Ｍｇ、Ｓｎ、Ｚｒ、Ｃｕ、Ｍｏ、Ｌａ、Ｃｅ、Ｖ、Ｓｉ、Ｓ、Ｓｃ、Ｓｂ、Ｙ、Ｒｈ、Ｐｄ、Ｎｄ、Ｎｂ、Ｂ、Ｐ、Ｇｅ、Ａｇ、Ａｕ、Ｒｕ、Ｐｒ、Ｂｉ、Ｗ、Ｒｅ、Ｔｅ等の元素の１種又は２種以上によって置換されていてもよい。ただし、Ｔｉ及びＡｌ以外の置換元素の合計量はＦｅ １２ｍｏｌに対して０．０７７ｍｏｌ以下（Ｆｅに対して０．６ａｔｍ．％に相当する）であることが好ましく、より好ましくは０．０６４ｍｏｌ以下（Ｆｅに対して０．５ａｔｍ．％に相当する）、更により好ましくは０．０５１ｍｏｌ以下（Ｆｅに対して０．４ａｔｍ．％に相当する）である。Ｔｉ及びＡｌ以外の置換元素の含有量がＦｅ １２ｍｏｌに対して０．０７７ｍｏｌを超える場合には、磁性不純物が生成し、粉体ＳＦＤが大きくなるため好ましくない。また、板状比を２．０未満に維持することが困難になると共に、磁気記録媒体用磁性粒子粉末として要求される磁気特性（保磁力Ｈｃ及び飽和磁化値σｓ）のバランスが崩れるため好ましくない。 The hexagonal ferrite particle powder for magnetic recording media according to the present invention is represented by the general formula AFe 12-x / 2-2y / 3 Ti x Al y O 19 , but a part of Fe is further Co, Ni, Zn , Mn, Mg, Sn, Zr, Cu, Mo, La, Ce, V, Si, S, Sc, Sb, Y, Rh, Pd, Nd, Nb, B, P, Ge, Ag, Au, Ru, Pr , Bi, W, Re, Te, etc. may be substituted by one or more elements. However, the total amount of substitutional elements other than Ti and Al is preferably 0.077 mol or less with respect to 12 mol of Fe (corresponding to 0.6 atm.% With respect to Fe), more preferably 0.064 mol or less ( (Corresponding to 0.5 atm.% With respect to Fe), even more preferably 0.051 mol or less (corresponding to 0.4 atm.% With respect to Fe). When the content of substitutional elements other than Ti and Al exceeds 0.077 mol with respect to 12 mol of Fe, magnetic impurities are generated and the powder SFD becomes large, which is not preferable. Further, it is difficult to maintain the plate ratio below 2.0, and the balance of magnetic properties (coercive force Hc and saturation magnetization value σs) required for the magnetic particle powder for a magnetic recording medium is lost. .
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の平均板面径は１０〜３０ｎｍであり、好ましくは１０〜２８ｎｍ、より好ましくは１０〜２５ｎｍである。六方晶フェライト粒子粉末の平均板面径が３０ｎｍを超える場合には、粒子サイズが大きいため、粒子性ノイズをより低減することが難しく、高いＣ／Ｎ比を有する磁気記録媒体を得ることが困難となる。また、平均板面径が１０ｎｍ未満である場合には、磁性粒子粉末の微細化に伴う熱揺らぎの影響が大きくなるため好ましくない。 The average plate surface diameter of the hexagonal ferrite particles for magnetic recording media according to the present invention is 10 to 30 nm, preferably 10 to 28 nm, and more preferably 10 to 25 nm. When the average plate surface diameter of the hexagonal ferrite particle powder exceeds 30 nm, the particle size is large, so that it is difficult to further reduce the particulate noise, and it is difficult to obtain a magnetic recording medium having a high C / N ratio. It becomes. Moreover, when the average plate surface diameter is less than 10 nm, the influence of thermal fluctuation accompanying the miniaturization of the magnetic particle powder increases, which is not preferable.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の板状比は、後出評価方法により１．０以上２．０未満であることが好ましく、より好ましくは１．０〜１．８、更により好ましくは１．０〜１．６である。板状比が２．０以上の場合には、粒子間のスタッキングが多くなり、磁性塗料の製造時におけるビヒクル中への分散性が低下すると共に、粘度が増加する場合があるため好ましくない。 The plate ratio of the hexagonal ferrite particle powder for magnetic recording media according to the present invention is preferably 1.0 or more and less than 2.0, more preferably 1.0 to 1.8, more preferably 1.0 to 1.8. More preferably, it is 1.0-1.6. When the plate ratio is 2.0 or more, stacking between particles increases, dispersibility in the vehicle during production of the magnetic coating material decreases, and viscosity may increase, which is not preferable.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の粒子形状は、六角板状、球状、粒状、立方体状等を用いることができる。 The hexagonal ferrite particle powder for magnetic recording media according to the present invention may have a hexagonal plate shape, a spherical shape, a granular shape, a cubic shape, or the like.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末のＢＥＴ比表面積値は１０〜２００ｍ2／ｇが好ましく、より好ましくは１５〜１５０ｍ2／ｇ、更により好ましくは２０〜１００ｍ2／ｇである。ＢＥＴ比表面積値が１０ｍ2／ｇ未満の場合には、磁気記録媒体用磁性微粒子粉末が粗大であるため、これを用いて得られた磁気記録媒体の表面平滑性が低下し、それに起因して出力も向上し難くなる。また、短波長領域における飽和磁化値や保磁力値が低下すると共に粒子性ノイズが増大するため好ましくない。ＢＥＴ比表面積値が２００ｍ2／ｇを超える場合には、粒子の微細化による分子間力の増大により凝集を起こしやすいため、磁性塗料の製造時におけるビヒクル中への分散性が低下する。 BET specific surface area of the magnetic recording medium for the hexagonal ferrite particles according to the present invention is preferably 10 to 200 m 2 / g, more preferably 15~150m 2 / g, still more preferably is 20 to 100 m 2 / g . When the BET specific surface area is less than 10 m 2 / g, the magnetic fine particle powder for a magnetic recording medium is coarse, so that the surface smoothness of the magnetic recording medium obtained by using this decreases, resulting in that It becomes difficult to improve the output. In addition, the saturation magnetization value and the coercive force value in the short wavelength region are decreased, and particle noise is increased, which is not preferable. When the BET specific surface area value exceeds 200 m 2 / g, aggregation tends to occur due to an increase in intermolecular force due to finer particles, so that the dispersibility in the vehicle during the production of the magnetic coating material decreases.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の磁性不純物の有無の確認は後出評価方法により行い、本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、（１）ＸＲＤによる定性分析において、γ−Ｆｅ２Ｏ３を示すピークが認められないこと、（２）磁気特性の測定において、保磁力分布曲線のピークが１つであること、が好ましい。ＸＲＤによる定性分析において、γ−Ｆｅ２Ｏ３を示すピークが認められた場合、又は／及び、磁気特性の測定において、保磁力分布曲線のピークが２つ以上ある場合は磁性不純物が存在し、粉体ＳＦＤが拡大する傾向にあるため、好ましくない。 The presence or absence of magnetic impurities in the hexagonal ferrite particles for magnetic recording media according to the present invention is confirmed by the later-described evaluation method. The hexagonal ferrite particles for magnetic recording media according to the present invention are (1) qualitative analysis by XRD. It is preferable that no peak showing γ-Fe 2 O 3 is observed in (2), and that the coercive force distribution curve has one peak in the measurement of magnetic properties. In the qualitative analysis by XRD, when a peak indicating γ-Fe 2 O 3 is observed, or / and in the measurement of magnetic properties, if there are two or more peaks of the coercive force distribution curve, magnetic impurities are present, Since the powder SFD tends to expand, it is not preferable.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の磁気特性は、保磁力（Ｈｃ）が１１９．４〜３９７．９ｋＡ／ｍが好ましく、より好ましくは１２７．３〜３１８．３ｋＡ／ｍであり、飽和磁化値が３０〜７０Ａｍ２／ｋｇが好ましく、より好ましくは３５〜７０Ａｍ２／ｋｇである。また、粉体ＳＦＤは１．５以下であり、好ましくは１．２以下である。 As for the magnetic properties of the hexagonal ferrite particles for magnetic recording media according to the present invention, the coercive force (Hc) is preferably 119.4 to 397.9 kA / m, more preferably 127.3 to 318.3 kA / m. a saturation magnetization value is 30~70Am 2 / kg weight, more preferably 35~70Am 2 / kg. The powder SFD is 1.5 or less, preferably 1.2 or less.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、必要により、六方晶フェライト粒子粉末の粒子表面を、アルミニウムの水酸化物、アルミニウムの酸化物、ケイ素の水酸化物及びケイ素の酸化物、コバルトの水酸化物及びコバルトの酸化物から選ばれた１種又は２種以上の化合物（以下、「アルミニウムの水酸化物等」という。）で被覆しておいてもよい。アルミニウムの水酸化物等で被覆処理を行うことにより、磁性塗料中に分散させた場合に、結合剤樹脂とのなじみがよく、所望の分散度がより得られ易い。 The hexagonal ferrite particle powder for magnetic recording media according to the present invention, if necessary, the particle surface of the hexagonal ferrite particle powder, aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide, You may coat | cover with the 1 type (s) or 2 or more types of compounds (henceforth "aluminum hydroxide etc.") chosen from the hydroxide of cobalt and the oxide of cobalt. By carrying out a coating treatment with aluminum hydroxide or the like, when dispersed in a magnetic paint, it is well-familiar with the binder resin and a desired degree of dispersion is more easily obtained.
なお、六方晶フェライト粒子粉末の結晶構造中のＡｌ、Ｓｉ又はＣｏと、表面処理により被覆されている粒子表面に存在するＡｌ、Ｓｉ又はＣｏについては、「Ｘ線光電子分析装置 ＥＳＣＡ３５００」（島津製作所株式会社製）を用い、高速Ａｒイオンエッチングによりエッチング処理を行ないながら深さ方向のＡｌ原子、Ｓｉ原子又はＣｏ原子とＦｅ原子の存在比の測定を行うことにより、存在位置の違いを判定することができる。 Regarding the Al, Si or Co in the crystal structure of the hexagonal ferrite particle powder and the Al, Si or Co present on the surface of the particles coated by the surface treatment, “X-ray photoelectron analyzer ESCA3500” (Shimadzu Corporation) The difference in location is determined by measuring the abundance ratio of Al atoms, Si atoms or Co atoms and Fe atoms in the depth direction while performing etching processing by high-speed Ar ion etching. Can do.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末を得るための製造法としては、所望のフェライト組成になるように混合した原材料とガラス形成物質を溶融し、急冷して非晶質体とし、次いで再加熱処理した後、洗浄・粉砕して六方晶フェライト粒子粉末を得るガラス結晶化法、所望のフェライト組成のアルカリ性懸濁液を１００℃以上で液相加熱し、洗浄・乾燥した後９００℃前後で熱処理し、粉砕して六方晶フェライト粒子粉末を得る水熱合成法、所望のフェライト組成の金属塩溶液をアルカリで中和し、得られた鉄塩とバリウム塩の共沈物を水洗・乾燥した後８００℃で熱処理し、粉砕して六方晶フェライト粒子粉末を得る共沈−焼成法等があるが、前述の特性を満たすものであれば特に限定されない。 As a manufacturing method for obtaining a hexagonal ferrite particle powder for magnetic recording media according to the present invention, the raw material and the glass-forming substance mixed so as to have a desired ferrite composition are melted and rapidly cooled to an amorphous body, Next, after reheating treatment, glass crystallization method to obtain hexagonal ferrite particle powder by washing and pulverizing, liquid phase heating of alkaline suspension of desired ferrite composition at 100 ° C. or higher, washing and drying, 900 ° C. Hydrothermal synthesis method to obtain hexagonal ferrite particle powder by heat treatment before and after grinding, neutralize metal salt solution of desired ferrite composition with alkali, wash the resulting iron salt and barium salt coprecipitate with water There is a coprecipitation-firing method in which, after drying, heat treatment at 800 ° C. and pulverization to obtain hexagonal ferrite particle powder, there is no particular limitation as long as it satisfies the aforementioned characteristics.
＜作用＞
本発明において最も重要な点は、下記一般式で表される本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、磁気記録媒体のノイズをより低減できるという事実である。ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９
（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）
（ｘ：０．０５〜３、ｙ：０．１〜３）
<Action>
The most important point in the present invention is the fact that the hexagonal ferrite particle powder for magnetic recording media according to the present invention represented by the following general formula can further reduce the noise of the magnetic recording media. AFe 12-x / 2-2y / 3 Ti x Al y O 19
(A: one or more elements selected from Ba, Sr and Ca)
(X: 0.05~3, y: 0.1 ~3)
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末が、磁気記録媒体のノイズをより低減できた理由について、本発明者は、次のように考えている。 The present inventor considers the reason why the hexagonal ferrite particle powder for magnetic recording media according to the present invention can further reduce the noise of the magnetic recording media as follows.
即ち、磁気記録媒体のノイズ低減には、粒子サイズの影響が大きいことから、磁気記録媒体に用いる磁性粒子粉末の粒子サイズはできるだけ小さい方が有利であることが知られている。しかしながら、六方晶フェライト粒子粉末は、前述したとおり、一般に、粒子形状が板状であるため粒子同士がスタッキングしやすく、そのため、１個１個の粒子は微細化されているにもかかわらず挙動粒子体積が大きくなるため、ノイズ低減効果が得られ難いという問題を有している。本発明に係る六方晶フェライト粒子粉末は、ＡＦｅ１２Ｏ１９で表されるマグネトプランバイト型フェライト粒子粉末のＦｅの置換元素としてＴｉ及びＡｌを用いることで、板状比を２．０未満とすることができたことによって、六方晶系フェライト粒子粉末の欠点であったスタッキングを防止できたため、磁気記録媒体のノイズ低減を達成できたものと本発明者は考えている。 That is, it is known that the particle size of the magnetic particle powder used for the magnetic recording medium is advantageously as small as possible because the influence of the particle size is large for noise reduction of the magnetic recording medium. However, as described above, the hexagonal ferrite particle powder generally has a plate-like shape, so that the particles are easy to stack with each other. Since the volume increases, there is a problem that it is difficult to obtain a noise reduction effect. The hexagonal ferrite particle powder according to the present invention uses Ti and Al as substitution elements for Fe in the magnetoplumbite type ferrite particle powder represented by AFe 12 O 19 , thereby setting the plate ratio to less than 2.0. The inventor believes that the noise reduction of the magnetic recording medium can be achieved because the stacking that has been a defect of the hexagonal ferrite particles can be prevented.
また、本発明者は、ＡＦｅ１２Ｏ１９で表されるマグネトプランバイト型フェライト粒子粉末のＦｅの置換元素としてＴｉ及びＡｌ以外の元素を用いること、及び、Ｆｅの置換元素としてＴｉ及びＡｌ以外の元素をＦｅ １２ｍｏｌに対して０．０７７ｍｏｌ（Ｆｅに対して０．６ａｔｍ．％に相当する）を超えて用いた場合、磁性不純物が生成し、粉体ＳＦＤが拡大することを見出した。本発明に係る六方晶フェライト粒子粉末は、マグネトプランバイト型フェライト粒子粉末のＦｅの置換元素としてＴｉ及びＡｌを選択することにより、磁性不純物の生成を抑制し、粉体ＳＦＤを改善することができたため、磁気記録媒体のノイズ低減を達成できたものと本発明者は考えている。 In addition, the present inventor uses an element other than Ti and Al as the substitution element of Fe in the magnetoplumbite type ferrite particle powder represented by AFe 12 O 19 , and uses other than Ti and Al as the substitution element of Fe. It has been found that when the element is used in an amount exceeding 0.077 mol (corresponding to 0.6 atm.% With respect to Fe) with respect to 12 mol of Fe, magnetic impurities are generated and the powder SFD expands. The hexagonal ferrite particle powder according to the present invention can suppress the generation of magnetic impurities and improve the powder SFD by selecting Ti and Al as substitution elements of Fe in the magnetoplumbite type ferrite particle powder. Therefore, the present inventor considers that noise reduction of the magnetic recording medium has been achieved.
以下に、本発明における実施例を示し、本発明を具体的に説明する。 Examples of the present invention are shown below, and the present invention will be specifically described.
六方晶フェライト粒子粉末の平均板面径は、透過型電子顕微鏡を用いて複数の視野において粒子の写真を撮影し、該写真を用いて粒子３６０個以上について板面径を測定し、その平均値で粒子の平均板面径を示した。なお、平均板面径を求める際の粒子の選定基準としては、粒子同士が重なっており、境界がはっきりしていないものは測定を行わないものとした。 The average plate surface diameter of the hexagonal ferrite particle powder is obtained by taking a photograph of particles in a plurality of fields using a transmission electron microscope, measuring the plate surface diameter of 360 or more particles using the photograph, and calculating the average value. Shows the average plate surface diameter of the particles. In addition, as selection criteria of the particle | grains at the time of calculating | requiring an average plate | board surface diameter, the particle | grains overlapped and the thing where the boundary was not clear shall not be measured.
六方晶フェライト粒子粉末の板状比は、Ｘ線回折装置「ＲＩＮＴ２５００」（株式会社リガク製）を用いて、ＣｕのＫα線を線源とした面指数（２，２，０）面と（０，０，６）面のそれぞれのピークの半値幅を求め、Ｓｃｈｅｒｒｅｒの式より結晶子径を計算し、（２，２，０）面の結晶子径／（０，０，６）面の結晶子径を板状比として示した。 The plate-like ratio of the hexagonal ferrite particle powder was determined by using an X-ray diffractometer “RINT2500” (manufactured by Rigaku Corporation) and a plane index (2,2,0) plane using Cu Kα ray as a radiation source and (0 , 0,6) plane, the half width of each peak is calculated, the crystallite diameter is calculated from Scherrer's formula, and the crystallite diameter of (2,2,0) plane / crystal of (0,0,6) plane The child diameter was shown as a plate ratio.
比表面積は、「モノソーブＭＳ−１１」（カンタクロム株式会社製）を用いて、ＢＥＴ法により測定した値で示した。 The specific surface area was shown by the value measured by BET method using “Monosorb MS-11” (manufactured by Kantachrome Co., Ltd.).
六方晶フェライト粒子粉末に含有される各種元素の含有量は、試料０．２ｇと王水１０ｍｌとを１００ｍｌのフッ素樹脂製ビーカーへ入れて攪拌し、２４０℃で２０分保持して溶解させ、この溶液を「誘導結合プラズマ発光分光分析装置 ＳＰＳ４０００」（セイコー電子工業株式会社製）を用いて測定した。 The content of various elements contained in the hexagonal ferrite particle powder was as follows: 0.2 g of sample and 10 ml of aqua regia were placed in a 100 ml fluororesin beaker and stirred, and kept at 240 ° C. for 20 minutes to dissolve. The solution was measured using an “inductively coupled plasma emission spectrometer SPS4000” (manufactured by Seiko Denshi Kogyo Co., Ltd.).
六方晶フェライト粒子粉末の磁性不純物の有無については、以下に示す２つの方法によって確認を行った。
（１）ＸＲＤによる定性分析を行ない、γ−Ｆｅ２Ｏ３を示すピークの有無の確認を行った。
（２）「振動試料型磁力計ＶＳＭ ＳＳＭ−５−１５」（東英工業株式会社製）を用いて外部磁場１１９３．７ｋＡ／ｍの条件で測定を行ない、保磁力分布曲線にピークが２つ以上ある場合は磁性不純物が存在すると判定した。
The presence or absence of magnetic impurities in the hexagonal ferrite particle powder was confirmed by the following two methods.
(1) Qualitative analysis was performed by XRD, and the presence or absence of a peak indicating γ-Fe 2 O 3 was confirmed.
(2) Measurement was performed under the condition of an external magnetic field of 1193.7 kA / m using a “vibrating sample magnetometer VSM SSM-5-15” (manufactured by Toei Kogyo Co., Ltd.), and there were two peaks in the coercive force distribution curve. When there was more, it was determined that magnetic impurities were present.
六方晶フェライト粒子粉末の磁気特性は、「振動試料型磁力計ＶＳＭ ＳＳＭ−５−１５」（東英工業株式会社製）を用いて外部磁場１１９３．７ｋＡ／ｍの条件で測定した。また、粉体ＳＦＤは、印加磁場が０〜３９７．９ｋＡ／ｍの範囲ではスイープ速度を７９．６（ｋＡ／ｍ）／分とし、３９７．９〜１，１９３．７ｋＡ／ｍの範囲ではスイープ速度を３９７．９（ｋＡ／ｍ）／分として測定した。 The magnetic properties of the hexagonal ferrite particle powder were measured using a “vibrating sample magnetometer VSM SSM-5-15” (manufactured by Toei Kogyo Co., Ltd.) under an external magnetic field of 1193.7 kA / m. The powder SFD has a sweep speed of 79.6 (kA / m) / min when the applied magnetic field is in the range of 0 to 397.9 kA / m and sweeps in the range of 397.9 to 193.7 kA / m. The rate was measured as 397.9 (kA / m) / min.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末の磁気記録媒体における特性を評価・確認するため、以下に示す方法で磁気テープを作製し評価した。 In order to evaluate and confirm the characteristics of the hexagonal ferrite particles for magnetic recording media according to the present invention in the magnetic recording media, magnetic tapes were prepared and evaluated by the following methods.
非磁性下地層形成用の非磁性塗料組成
非磁性下地層用ヘマタイト粒子粉末 １００．０重量部、
スルホン酸カリウム基を有する塩化ビニル系共重合樹脂 １１．８重量部、
スルホン酸ナトリウム基を有するポリウレタン樹脂 １１．８重量部、
シクロヘキサノン ７８．３重量部、
メチルエチルケトン １９５．８重量部、
トルエン １１７．５重量部、
硬化剤（ポリイソシアネート） ３．０重量部、
潤滑剤（ブチルステアレート） １．０重量部。
Nonmagnetic coating composition for nonmagnetic underlayer formation 100.0 parts by weight of hematite particle powder for nonmagnetic underlayer,
11.8 parts by weight of a vinyl chloride copolymer resin having a potassium sulfonate group,
11.8 parts by weight of a polyurethane resin having a sodium sulfonate group,
78.3 parts by weight of cyclohexanone,
195.8 parts by weight of methyl ethyl ketone,
117.5 parts by weight of toluene,
Curing agent (polyisocyanate) 3.0 parts by weight,
Lubricant (butyl stearate) 1.0 part by weight.
非磁性下地層用ヘマタイト粒子粉末と結合剤樹脂溶液（スルホン酸カリウム基を有する塩化ビニル系共重合樹脂３０重量％とシクロヘキサノン７０重量％）及びシクロヘキサノンとを固形分が７２ｗｔ％となるよう混合し、自動乳鉢を用いて３０分間混練して混練物を得た。 A non-magnetic underlayer hematite particle powder, a binder resin solution (vinyl chloride copolymer resin having potassium sulfonate group 30 wt% and cyclohexanone 70 wt%) and cyclohexanone are mixed so that the solid content is 72 wt%; A kneaded product was obtained by kneading for 30 minutes using an automatic mortar.
次いで、上記非磁性塗料組成となるように、上記混練物と、追加の結合剤樹脂溶液（スルホン酸ナトリウム基を有するポリウレタン樹脂３０重量％、溶剤（メチルエチルケトン：トルエン＝１：１）７０重量％）、シクロヘキサノン、メチルエチルケトン及びトルエン１．５ｍｍφガラスビーズ９５ｇと共に１４０ｍｌガラス瓶に添加し、ペイントシェーカーで６時間混合・分散を行って非磁性塗料組成物を得た。その後、潤滑剤及び硬化剤を加え、更に、ペイントシェーカーで１５分間混合・分散した後、３μｍの平均孔径を有するフィルターを用いてろ過し、非磁性下地層用非磁性塗料を調整した。 Next, the kneaded product and an additional binder resin solution (30% by weight of a polyurethane resin having a sodium sulfonate group, 70% by weight of a solvent (methyl ethyl ketone: toluene = 1: 1)) so that the nonmagnetic coating composition is obtained. , Cyclohexanone, methyl ethyl ketone and 95 g of toluene 1.5 mmφ glass beads were added to a 140 ml glass bottle and mixed and dispersed for 6 hours with a paint shaker to obtain a nonmagnetic coating composition. Thereafter, a lubricant and a curing agent were added, and further mixed and dispersed for 15 minutes with a paint shaker, followed by filtration using a filter having an average pore diameter of 3 μm to prepare a nonmagnetic paint for a nonmagnetic underlayer.
上記非磁性下地層用非磁性塗料を厚さ４．５μｍの芳香族ポリアミドフィルム上に塗布し、次いで、乾燥させることにより非磁性下地層を形成した。 The nonmagnetic coating for the nonmagnetic underlayer was applied onto an aromatic polyamide film having a thickness of 4.5 μm, and then dried to form a nonmagnetic underlayer.
磁気記録層形成用の磁性塗料組成
六方晶フェライト粒子粉末 １００．０重量部、
スルホン酸カリウム基を有する塩化ビニル系共重合樹脂 １２．５重量部、
スルホン酸ナトリウム基を有するポリウレタン樹脂 ７．５重量部、
研磨剤（ＡＫＰ−５０） ５．０重量部、
カーボンブラック ２．０重量部、
潤滑剤（ミリスチン酸：ステアリン酸ブチル＝１：２） ３．０重量部、
硬化剤（ポリイソシアネート） ５．０重量部、
シクロヘキサノン １７０．０重量部、
メチルエチルケトン １７０．０重量部。
Magnetic coating composition for magnetic recording layer formation Hexagonal ferrite particle powder 100.0 parts by weight,
12.5 parts by weight of a vinyl chloride copolymer resin having a potassium sulfonate group,
7.5 parts by weight of a polyurethane resin having a sodium sulfonate group,
Abrasive (AKP-50) 5.0 parts by weight,
2.0 parts by weight of carbon black,
Lubricant (myristic acid: butyl stearate = 1: 2) 3.0 parts by weight,
Curing agent (polyisocyanate) 5.0 parts by weight,
170.0 parts by weight of cyclohexanone,
170.0 parts by weight of methyl ethyl ketone.
六方晶フェライト粒子粉末と研磨剤、カーボンブラック、結合剤樹脂溶液（スルホン酸カリウム基を有する塩化ビニル系共重合樹脂３０重量％とシクロヘキサノン７０重量％）及びシクロヘキサノンとを固形分が７６ｗｔ％となるよう混合し、自動乳鉢を用いて４０分間混練して混練物を得た。 Hexagonal ferrite particles, abrasive, carbon black, binder resin solution (30% by weight of vinyl chloride copolymer resin having potassium sulfonate group and 70% by weight of cyclohexanone) and cyclohexanone so that the solid content becomes 76% by weight. They were mixed and kneaded for 40 minutes using an automatic mortar to obtain a kneaded product.
次いで、上記磁性塗料組成となるように、上記混練物と、追加の結合剤樹脂溶液（スルホン酸ナトリウム基を有するポリウレタン樹脂３０重量％、溶剤（メチルエチルケトン：トルエン＝１：１）７０重量％）、シクロヘキサノン、メチルエチルケトン及びトルエン１．５ｍｍφガラスビーズ９５ｇと共に１４０ｍｌガラス瓶に添加し、ペイントシェーカーで１２時間混合・分散を行って磁性塗料組成物を得た。その後、潤滑剤及び硬化剤を加え、更に、ペイントシェーカーで１５分間混合・分散した後、３μｍの平均孔径を有するフィルターを用いてろ過し、磁気記録層用磁性塗料を調整した。 Next, the kneaded product and an additional binder resin solution (30% by weight of a polyurethane resin having a sodium sulfonate group, 70% by weight of a solvent (methyl ethyl ketone: toluene = 1: 1)) so that the magnetic coating composition is obtained, A magnetic coating composition was obtained by adding to a 140 ml glass bottle together with 95 g of cyclohexanone, methyl ethyl ketone and toluene 1.5 mmφ glass beads, and mixing and dispersing in a paint shaker for 12 hours. Thereafter, a lubricant and a curing agent were added, and further mixed and dispersed for 15 minutes with a paint shaker, followed by filtration using a filter having an average pore diameter of 3 μm to prepare a magnetic coating material for a magnetic recording layer.
上記磁気記録層用塗料を、乾燥後の厚さが１．５μｍになるよう前記非磁性下地層の上に塗布した後、磁場中において配向・乾燥した。その後、６０℃で２４時間硬化反応を行い、１２．７ｍｍ幅にスリットして磁気テープを得た。 The magnetic recording layer coating composition was applied on the nonmagnetic underlayer so that the thickness after drying was 1.5 μm, and then oriented and dried in a magnetic field. Thereafter, a curing reaction was performed at 60 ° C. for 24 hours, and a magnetic tape was obtained by slitting to a width of 12.7 mm.
磁気テープの磁気特性は、「振動試料型磁力計ＶＳＭ ＳＳＭ−５−１５」（東英工業株式会社製）を用いて外部磁場１１９３．７ｋＡ／ｍの条件で測定した。また磁気テープのＳＦＤは、印加磁場が０〜３９７．９ｋＡ／ｍの範囲ではスイープ速度を７９．６（ｋＡ／ｍ）／分とし、３９７．９〜１，１９３．７ｋＡ／ｍの範囲ではスイープ速度を３９７．９（ｋＡ／ｍ）／分として測定した。 The magnetic characteristics of the magnetic tape were measured using a “vibrating sample magnetometer VSM SSM-5-15” (manufactured by Toei Kogyo Co., Ltd.) under an external magnetic field of 1193.7 kA / m. The SFD of the magnetic tape sweeps when the applied magnetic field is in the range of 0 to 397.9 kA / m and the sweep speed is 79.6 (kA / m) / min, and in the range of 397.9 to 193.7 kA / m. The rate was measured as 397.9 (kA / m) / min.
磁気テープの塗膜表面の光沢度は、「グロスメーター ＵＧＶ−５Ｄ」（スガ試験機株式会社製）を用いて入射角４５°で測定した値であり、標準板光沢を８６．３％とした時の値を％で示したものである。 The glossiness of the coating film surface of the magnetic tape is a value measured at an incident angle of 45 ° using “Gloss meter UGV-5D” (manufactured by Suga Test Instruments Co., Ltd.), and the standard plate gloss is 86.3%. The hour value is shown in%.
表面粗度Ｒａは、「ＺＹＧＯ ＮｅｗＶｉｅｗ６００Ｓ」（ＺＹＧＯ株式会社製）を用いて塗膜の中心線平均粗さを測定した。 Surface roughness Ra measured the centerline average roughness of the coating film using "ZYGO NewView600S" (made by ZYGO Corporation).
磁気記録媒体を構成する非磁性支持体及び磁気記録層の各層の厚みは、デジタル電子マイクロメーターＫ３５１Ｃ（安立電気株式会社製）を用いて測定した。 The thickness of each layer of the nonmagnetic support and the magnetic recording layer constituting the magnetic recording medium was measured using a digital electronic micrometer K351C (manufactured by Anritsu Electric Co., Ltd.).
磁気テープの電磁変換特性は、ドラムテスターを用い、記録ヘッドにはＭＩＧヘッドを、再生用ヘッドにはＭＲヘッドを用いて測定を行った。ヘッドと磁気テープとの相対速度は２．５ｍ／ｓｅｃとし、記録周波数１０ＭＨｚにおける再生信号出力（Ｃ）及び記録周波数９ＭＨｚにおける出力をノイズ信号出力（Ｎ）を、それぞれ後出比較例２−１を０ｄＢ（基準テープ）として、基準テープに対する相対値として求めた。またＣ／Ｎはこれら再生信号出力（Ｃ）とノイズ信号出力（Ｎ）を用いて示した。 The electromagnetic conversion characteristics of the magnetic tape were measured using a drum tester, a MIG head as a recording head, and an MR head as a reproducing head. The relative speed between the head and the magnetic tape is 2.5 m / sec. The reproduction signal output (C) at a recording frequency of 10 MHz and the output at a recording frequency of 9 MHz are noise signal outputs (N). The relative value with respect to the reference tape was determined as 0 dB (reference tape). C / N is shown using these reproduction signal output (C) and noise signal output (N).
磁気テープの劣化は、磁気テープを温度６０℃、相対湿度９０％の環境下で１４日間保存し、保存前と保存後の磁気テープそれぞれについて、前述の電磁変換特性を測定したときと同様の条件で得られるエンベロープより、単位時間当たりのドロップアウトの個数をカウントし、保存前に対する保存後のドロップアウトの増加量で示した。 The deterioration of the magnetic tape is the same condition as when the magnetic tape was stored for 14 days in an environment of a temperature of 60 ° C. and a relative humidity of 90%, and the electromagnetic conversion characteristics were measured for each of the magnetic tape before and after storage. From the envelope obtained in step 1, the number of dropouts per unit time was counted and indicated by the amount of increase in dropout after storage compared to before storage.
＜実施例１：磁気記録媒体用六方晶フェライト粒子粉末の製造＞
ＢａＣｌ２・２Ｈ２Ｏ ０．８１７ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ６．００ｍｏｌ、ＴｉＣｌ４ ０．５４ｍｏｌに純水を加えて溶解し、７Ｌの混合溶液を調製した。次いで、１８．５５ｍｏｌ／ＬのＮａＯＨ水溶液５Ｌを攪拌させながら前記混合溶液を２００ｍＬ／ｍｉｎ．の流量でＮａＯＨ水溶液中に添加した後、６０℃で２時間反応を行った。次に、純水を用いて十分に水洗し、共沈物を含む１０Ｌのスラリーとした後、酢酸を用いてｐＨ値を８．５に調整し、その後、アルミン酸ナトリウム ０．２７ｍｏｌを添加して３０分間攪拌して共沈混合物とした。次いで、フラックスとしてＮａＣｌを、ろ過・乾燥後の前記共沈混合物１００重量部に対して３０重量部となるように添加し、ろ過・乾燥してフラックスを含む共沈混合物を得た。
<Example 1: Production of hexagonal ferrite particle powder for magnetic recording medium>
Pure water was added to and dissolved in BaCl 2 .2H 2 O 0.817 mol, FeCl 3 .6H 2 O 6.00 mol, and TiCl 4 0.54 mol to prepare a 7 L mixed solution. Next, while stirring 5 L of 18.55 mol / L NaOH aqueous solution, the mixed solution was stirred at 200 mL / min. Was added to an aqueous NaOH solution at a flow rate of 2 ° C., followed by reaction at 60 ° C. for 2 hours. Next, after thoroughly washing with pure water to make a 10 L slurry containing coprecipitate, the pH value was adjusted to 8.5 with acetic acid, and then 0.27 mol of sodium aluminate was added. For 30 minutes to obtain a coprecipitation mixture. Next, NaCl as a flux was added to 30 parts by weight with respect to 100 parts by weight of the coprecipitation mixture after filtration and drying, and filtration and drying were performed to obtain a coprecipitation mixture containing the flux.
次いで、得られたフラックスを含む共沈混合物を空気雰囲気下、７００℃の温度で４時間焼成し、得られた焼成物に純水１Ｌを加えて分散スラリーとした。得られたスラリーを、塩酸を用いてｐＨ値を２に調製して６０分間保持して酸処理を行い、水酸化ナトリウム水溶液を用いてｐＨ値を５に調整した後、水洗・ろ過・乾燥・粉砕して、実施例１の六方晶フェライト粒子粉末を得た。 Subsequently, the coprecipitation mixture containing the obtained flux was fired at 700 ° C. for 4 hours in an air atmosphere, and 1 L of pure water was added to the obtained fired product to obtain a dispersed slurry. The obtained slurry was adjusted to pH value 2 with hydrochloric acid and kept for 60 minutes for acid treatment, adjusted to pH value 5 with aqueous sodium hydroxide solution, washed with water, filtered, dried, By grinding, the hexagonal ferrite particle powder of Example 1 was obtained.
得られた六方晶フェライト粒子粉末は粒状であり、平均板面径は１７．７ｎｍ、板状比は１．２、ＢＥＴ比表面積値は４５．３ｍ２／ｇであり、保磁力値（Ｈｃ）は１５５．２ｋＡ／ｍ、飽和磁化（σｓ）は４４．５Ａｍ２／ｋｇ、粉体ＳＦＤは０．８３であった。ＸＲＤの定性分析において、γ−Ｆｅ２Ｏ３のピークは認められなかった。また、磁気特性の保磁力分布曲線では、１つのピークしか認められなかった。ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９の組成式において、ＡはＢａ、ｘは１．０、ｙは０．５であった。 The obtained hexagonal ferrite particle powder is granular, the average plate surface diameter is 17.7 nm, the plate ratio is 1.2, the BET specific surface area value is 45.3 m 2 / g, and the coercive force value (Hc) Was 155.2 kA / m, the saturation magnetization (σs) was 44.5 Am 2 / kg, and the powder SFD was 0.83. In the qualitative analysis of XRD, no peak of γ-Fe 2 O 3 was observed. Moreover, only one peak was recognized in the coercive force distribution curve of the magnetic characteristics. In the composition formula of AFe 12-x / 2-2y / 3 Ti x Al y O 19 , A was Ba, x was 1.0, and y was 0.5.
実施例２：
ＢａＣｌ２・２Ｈ２Ｏ ０．８１７ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ６．００ｍｏｌ、ＴｉＣｌ４ ０．５４ｍｏｌに純水を加えて溶解し、７Ｌの混合溶液を調製した。次いで、１８．５５ｍｏｌ／ＬのＮａＯＨ水溶液５Ｌを攪拌させながら前記混合溶液を２００ｍＬ／ｍｉｎ．の流量でＮａＯＨ水溶液中に添加した後、６０℃で４時間反応を行った。次に、純水を用いて十分に水洗し、共沈物を含む１０Ｌのスラリーとした後、酢酸を用いてｐＨ値を８．５に調整し、その後、アルミン酸ナトリウム ０．３８ｍｏｌを添加して３０分間攪拌して共沈混合物とした。次いで、フラックスとしてＮａＣｌを、ろ過・乾燥後の前記共沈混合物１００重量部に対して３０重量部となるように添加し、ろ過・乾燥してフラックスを含む共沈混合物を得た。
Example 2:
Pure water was added to and dissolved in BaCl 2 .2H 2 O 0.817 mol, FeCl 3 .6H 2 O 6.00 mol, and TiCl 4 0.54 mol to prepare a 7 L mixed solution. Next, while stirring 5 L of 18.55 mol / L NaOH aqueous solution, the mixed solution was stirred at 200 mL / min. Was added to an aqueous NaOH solution at a flow rate of 4 ° C., followed by reaction at 60 ° C. for 4 hours. Next, after sufficiently washing with pure water to make a 10 L slurry containing coprecipitate, the pH value is adjusted to 8.5 with acetic acid, and then 0.38 mol of sodium aluminate is added. For 30 minutes to obtain a coprecipitation mixture. Next, NaCl as a flux was added to 30 parts by weight with respect to 100 parts by weight of the coprecipitation mixture after filtration and drying, and filtration and drying were performed to obtain a coprecipitation mixture containing the flux.
次いで、得られたフラックスを含む共沈混合物を空気雰囲気下、６７０℃の温度で６時間焼成し、得られた焼成物に純水１Ｌを加えて分散スラリーとした。得られたスラリーを、塩酸を用いてｐＨ値を２に調製して６０分間保持して酸処理を行い、水酸化ナトリウム水溶液を用いてｐＨ値を５に調整した後、水洗・ろ過・乾燥・粉砕して、実施例２の六方晶フェライト粒子粉末を得た。得られた六方晶フェライト粒子粉末の諸特性を表１に示す。 Next, the coprecipitation mixture containing the obtained flux was fired at a temperature of 670 ° C. for 6 hours in an air atmosphere, and 1 L of pure water was added to the obtained fired product to obtain a dispersion slurry. The obtained slurry was adjusted to pH value 2 with hydrochloric acid and kept for 60 minutes for acid treatment, adjusted to pH value 5 with aqueous sodium hydroxide solution, washed with water, filtered, dried, The hexagonal ferrite particle powder of Example 2 was obtained by pulverization. Table 1 shows various properties of the obtained hexagonal ferrite particle powder.
実施例３：
ＢａＣｌ２・２Ｈ２Ｏ ０．８１７ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ６．００ｍｏｌ、ＴｉＣｌ４ ０．５０ｍｏｌに純水を加えて溶解し、７Ｌの混合溶液を調製した。次いで、１８．５５ｍｏｌ／ＬのＮａＯＨ水溶液５Ｌを攪拌させながら前記混合溶液を２００ｍＬ／ｍｉｎ．の流量でＮａＯＨ水溶液中に添加した後、６０℃で４時間反応を行った。次に、純水を用いて十分に水洗し、共沈物を含む１０Ｌのスラリーとした後、酢酸を用いてｐＨ値を８．５に調整し、その後、アルミン酸ナトリウム ０．５５ｍｏｌを添加して３０分間攪拌して共沈混合物とした。次いで、フラックスとしてＮａＣｌを、ろ過・乾燥後の前記共沈混合物１００重量部に対して３０重量部となるように添加し、ろ過・乾燥してフラックスを含む共沈混合物を得た。
Example 3:
Pure water was added and dissolved in BaCl 2 .2H 2 O 0.817 mol, FeCl 3 .6H 2 O 6.00 mol, TiCl 4 0.50 mol to prepare a 7 L mixed solution. Next, while stirring 5 L of 18.55 mol / L NaOH aqueous solution, the mixed solution was stirred at 200 mL / min. Was added to an aqueous NaOH solution at a flow rate of 4 ° C., followed by reaction at 60 ° C. for 4 hours. Next, after thoroughly washing with pure water to make a 10 L slurry containing coprecipitate, the pH value was adjusted to 8.5 with acetic acid, and then 0.55 mol of sodium aluminate was added. For 30 minutes to obtain a coprecipitation mixture. Next, NaCl as a flux was added to 30 parts by weight with respect to 100 parts by weight of the coprecipitation mixture after filtration and drying, and filtration and drying were performed to obtain a coprecipitation mixture containing the flux.
次いで、得られたフラックスを含む共沈混合物を空気雰囲気下、７５０℃の温度で６時間焼成し、得られた焼成物に純水１Ｌを加えて分散スラリーとした。得られたスラリーを、塩酸を用いてｐＨ値を２に調製して６０分間保持して酸処理を行い、水酸化ナトリウム水溶液を用いてｐＨ値を５に調整した後、水洗・ろ過・乾燥・粉砕して、実施例３の六方晶フェライト粒子粉末を得た。得られた六方晶フェライト粒子粉末の諸特性を表１に示す。 Next, the coprecipitation mixture containing the obtained flux was fired at a temperature of 750 ° C. for 6 hours in an air atmosphere, and 1 L of pure water was added to the obtained fired product to obtain a dispersion slurry. The obtained slurry was adjusted to pH value 2 with hydrochloric acid and kept for 60 minutes for acid treatment, adjusted to pH value 5 with aqueous sodium hydroxide solution, washed with water, filtered, dried, By grinding, hexagonal ferrite particle powder of Example 3 was obtained. Table 1 shows various properties of the obtained hexagonal ferrite particle powder.
参考例４：
ＢａＣｌ２・２Ｈ２Ｏ ０．０８ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ０．６０ｍｏｌ、ＴｉＣｌ４ ０．１１ｍｏｌに純水を加えて溶解し、０．７Ｌの混合溶液を調製した。次いで、１８．５５ｍｏｌ／ＬのＮａＯＨ水溶液０．５Ｌを攪拌させながら、前記混合溶液を２０ｍＬ／ｍｉｎ．の流量で３５分間かけてＮａＯＨ水溶液中に添加し、オートクレーブを用いて１７０℃で６時間反応を行った後、室温まで冷却した。
Reference example 4:
Pure water was added and dissolved in 0.08 mol of BaCl 2 .2H 2 O, 0.60 mol of FeCl 3 .6H 2 O and 0.11 mol of TiCl 4 to prepare a 0.7 L mixed solution. Next, while stirring 0.5 L of 18.55 mol / L NaOH aqueous solution, the mixed solution was added at 20 mL / min. Was added to an aqueous NaOH solution at a flow rate of 35 minutes, reacted at 170 ° C. for 6 hours using an autoclave, and then cooled to room temperature.
次に、得られた反応溶液を、純水を用いて十分に水洗して六方晶フェライト粒子の前駆体を含む１Ｌのスラリーとした後、酢酸を用いてｐＨ値を８．５に調整し、超音波ホモジナイザー（ＢＲＡＮＳＯＮ株式会社製ＳｏｎｉｆｉｅｒＩＩ ｍｏｄｅｌ ４５０Ｄ）を用いて１０分間攪拌した。次いで、フラックスとしてＮａＣｌを、ろ過・乾燥後の前記六方晶フェライト粒子の前駆体１００重量部に対して３０重量部となるように添加し、ろ過・乾燥してフラックスを含む六方晶フェライト粒子の前駆体を得た。 Next, the obtained reaction solution was sufficiently washed with pure water to form a 1 L slurry containing a precursor of hexagonal ferrite particles, and then the pH value was adjusted to 8.5 using acetic acid. The mixture was stirred for 10 minutes using an ultrasonic homogenizer (Sonifier II model 450D manufactured by BRANSON Corporation). Next, NaCl as a flux is added to 30 parts by weight with respect to 100 parts by weight of the hexagonal ferrite particles after filtration and drying, and the precursor of hexagonal ferrite particles containing the flux is filtered and dried. Got the body.
上記で得られたフラックスを含む六方晶フェライト粒子の前駆体を、空気雰囲気下７５０℃の温度で６時間焼成し、得られた焼成物に純水１Ｌを加えて分散スラリーとした。得られたスラリーを、湿式粉砕後、塩酸を用いてｐＨ値を２に調製して酸処理を行った後、水酸化ナトリウム水溶液を用いてｐＨ値を５に調整し、水洗・ろ過・乾燥・粉砕して六方晶フェライト粒子粉末を得た。 The precursor of hexagonal ferrite particles containing the flux obtained above was fired at a temperature of 750 ° C. for 6 hours in an air atmosphere, and 1 L of pure water was added to the fired product to obtain a dispersed slurry. The obtained slurry was wet crushed, adjusted to pH value 2 with hydrochloric acid and acid-treated, adjusted to pH value 5 with aqueous sodium hydroxide solution, washed with water, filtered, dried, By grinding, hexagonal ferrite particle powder was obtained.
上記で得られた六方晶フェライト粒子粉末５５５ｇを純水に分散させてラインミル、ビーズミルを通して８Ｌの水分散スラリーを得た。次いで、４．５ｗｔ％の塩化コバルト水溶液を１００ｍＬ添加し、１０分間攪拌を行った。次いで、前記混合溶液を攪拌しながらｐＨ値が１４になるまでＮａＯＨ水溶液を添加し、３０分間攪拌後、１００℃まで昇温し、更に３時間混合・攪拌した。 655 g of the hexagonal ferrite particle powder obtained above was dispersed in pure water, and 8 L of water dispersion slurry was obtained through a line mill and a bead mill. Subsequently, 100 mL of 4.5 wt% cobalt chloride aqueous solution was added, and it stirred for 10 minutes. Next, an aqueous NaOH solution was added while stirring the mixed solution until the pH value became 14, and after stirring for 30 minutes, the temperature was raised to 100 ° C., and further mixed and stirred for 3 hours.
上記で得られた混合溶液をｐＨ値が１２以下になるまで水洗後、酢酸を用いてｐＨ値を９に調整し、更に水洗・ろ過・乾燥・粉砕して、参考例４のＣｏ化合物により表面被覆された六方晶フェライト粒子粉末を得た。得られたＣｏ化合物により表面被覆された六方晶フェライト粒子粉末の諸特性を表１に示す。 The mixed solution obtained above was washed with water until the pH value became 12 or less, adjusted to pH value 9 with acetic acid, further washed with water, filtered, dried and pulverized, and the surface was coated with the Co compound of Reference Example 4 A coated hexagonal ferrite particle powder was obtained. Table 1 shows various properties of the hexagonal ferrite particle powder surface-coated with the obtained Co compound.
実施例５：
ＢａＣｌ２・２Ｈ２Ｏ ０．８１０ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ６．００ｍｏｌ、ＴｉＣｌ４ ０．３２ｍｏｌ、に純水を加えて溶解し、７Ｌの混合溶液を調製した。次いで、１８．５５ｍｏｌ／ＬのＮａＯＨ水溶液５Ｌを攪拌させながら前記混合溶液を２００ｍＬ／ｍｉｎ．の流量でＮａＯＨ水溶液中に添加した後、６５℃で２時間反応を行った。次に、純水を用いて十分に水洗し、共沈物を含む１０Ｌのスラリーとした後、酢酸を用いてｐＨ値を８．５に調整し、その後、アルミン酸ナトリウム ０．２７ｍｏｌ及び塩化亜鉛 ０．０３４ｍｏｌを添加して３０分間攪拌して共沈混合物とした。次いで、フラックスとしてＮａＣｌを、ろ過・乾燥後の前記共沈混合物１００重量部に対して３０重量部となるように添加し、ろ過・乾燥してフラックスを含む共沈混合物を得た。
Example 5:
Pure water was added to BaCl 2 .2H 2 O 0.810 mol, FeCl 3 .6H 2 O 6.00 mol, TiCl 4 0.32 mol and dissolved to prepare a 7 L mixed solution. Next, while stirring 5 L of 18.55 mol / L NaOH aqueous solution, the mixed solution was stirred at 200 mL / min. Was added to an aqueous NaOH solution at a flow rate of 2 ° C., followed by reaction at 65 ° C. for 2 hours. Next, after thoroughly washing with pure water to make a 10 L slurry containing coprecipitate, the pH value was adjusted to 8.5 with acetic acid, and then 0.27 mol of sodium aluminate and zinc chloride. 0.034 mol was added and stirred for 30 minutes to obtain a coprecipitation mixture. Next, NaCl as a flux was added to 30 parts by weight with respect to 100 parts by weight of the coprecipitation mixture after filtration and drying, and filtration and drying were performed to obtain a coprecipitation mixture containing the flux.
次いで、得られたフラックスを含む共沈混合物を空気雰囲気下、６９０℃の温度で４時間焼成し、得られた焼成物に純水１Ｌを加えて分散スラリーとした。得られたスラリーを、塩酸を用いてｐＨ値を２に調製して６０分間保持して酸処理を行い、水酸化ナトリウム水溶液を用いてｐＨ値を５に調整した後、水洗・ろ過・乾燥・粉砕して、実施例５の六方晶フェライト粒子粉末を得た。 Subsequently, the coprecipitation mixture containing the obtained flux was baked for 4 hours at a temperature of 690 ° C. in an air atmosphere, and 1 L of pure water was added to the obtained baked product to obtain a dispersed slurry. The obtained slurry was adjusted to pH value 2 with hydrochloric acid and kept for 60 minutes for acid treatment, adjusted to pH value 5 with aqueous sodium hydroxide solution, washed with water, filtered, dried, By grinding, the hexagonal ferrite particle powder of Example 5 was obtained.
実施例６：
実施例１の六方晶フェライト粒子粉末５５０ｇを純水に分散させて、ラインミル、ビーズミルを通して８Ｌの水分散スラリーを得た。次いで、該スラリーに水酸化ナトリウム水溶液を添加してｐＨ値を９とした後、加熱して６０℃とし、このスラリー中に２０ｗｔ％のアルミン酸ナトリウム水溶液６８．２ｇ（六方晶フェライト粒子粉末に対してＡｌ換算で１．３重量％に相当する）を加え、３０分間保持した後、酢酸を用いてｐＨ値を９に調整した。この状態で３０分間保持した後、濾過・水洗・乾燥・粉砕し、粒子表面がアルミニウムの水酸化物等により被覆されている実施例６の六方晶フェライト粒子粉末を得た。得られた粒子表面がアルミニウムの水酸化物等により被覆されている六方晶フェライト粒子粉末の諸特性を表１に示す。
Example 6:
550 g of hexagonal ferrite particle powder of Example 1 was dispersed in pure water, and 8 L of water dispersion slurry was obtained through a line mill and a bead mill. Next, an aqueous solution of sodium hydroxide was added to the slurry to adjust the pH value to 9 and then heated to 60 ° C. In this slurry, 68.2 g of a 20 wt% aqueous sodium aluminate solution (based on the hexagonal ferrite particle powder) (Corresponding to 1.3% by weight in terms of Al) was added and held for 30 minutes, and then the pH value was adjusted to 9 using acetic acid. After holding for 30 minutes in this state, filtration, washing with water, drying and pulverization were performed to obtain hexagonal ferrite particle powder of Example 6 in which the particle surface was coated with aluminum hydroxide or the like. Table 1 shows properties of the obtained hexagonal ferrite particle powder whose surface is coated with aluminum hydroxide or the like.
比較例１：
ＢａＣｌ２・２Ｈ２Ｏ ０．８１７ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ６．００ｍｏｌ、ＴｉＣｌ４ ０．０１２ｍｏｌに純水を加えて溶解し、７Ｌの混合溶液を調製した。次いで、１８．５５ｍｏｌ／ＬのＮａＯＨ水溶液５Ｌを攪拌させながら前記混合溶液を２００ｍＬ／ｍｉｎ．の流量でＮａＯＨ水溶液中に添加した後、６０℃で２時間反応を行った。次に、純水を用いて十分に水洗し、共沈物を含む１０Ｌのスラリーとした後、酢酸を用いてｐＨ値を８．５に調整し、その後、アルミン酸ナトリウム １．９５ｍｏｌを添加して３０分間攪拌して共沈混合物とした。次いで、フラックスとしてＮａＣｌを、ろ過・乾燥後の前記共沈混合物１００重量部に対して３０重量部となるように添加し、ろ過・乾燥してフラックスを含む共沈混合物を得た。
Comparative Example 1:
Pure water was added to and dissolved in BaCl 2 .2H 2 O 0.817 mol, FeCl 3 .6H 2 O 6.00 mol, TiCl 4 0.012 mol to prepare a 7 L mixed solution. Next, while stirring 5 L of 18.55 mol / L NaOH aqueous solution, the mixed solution was stirred at 200 mL / min. Was added to an aqueous NaOH solution at a flow rate of 2 ° C., followed by reaction at 60 ° C. for 2 hours. Next, after thoroughly washing with pure water to make a 10 L slurry containing coprecipitate, the pH value was adjusted to 8.5 with acetic acid, and then 1.95 mol of sodium aluminate was added. For 30 minutes to obtain a coprecipitation mixture. Next, NaCl as a flux was added to 30 parts by weight with respect to 100 parts by weight of the coprecipitation mixture after filtration and drying, and filtration and drying were performed to obtain a coprecipitation mixture containing the flux.
次いで、得られたフラックスを含む共沈混合物を空気雰囲気下、７５０℃の温度で６時間焼成し、得られた焼成物に純水１Ｌを加えて分散スラリーとした。得られたスラリーを、塩酸を用いてｐＨ値を２に調製して６０分間保持して酸処理を行い、水酸化ナトリウム水溶液を用いてｐＨ値を５に調整した後、水洗・ろ過・乾燥・粉砕して、比較例１の六方晶フェライト粒子粉末を得た。得られた六方晶フェライト粒子粉末の諸特性を表１に示す。 Next, the coprecipitation mixture containing the obtained flux was fired at a temperature of 750 ° C. for 6 hours in an air atmosphere, and 1 L of pure water was added to the obtained fired product to obtain a dispersion slurry. The obtained slurry was adjusted to pH value 2 with hydrochloric acid and kept for 60 minutes for acid treatment, adjusted to pH value 5 with aqueous sodium hydroxide solution, washed with water, filtered, dried, By pulverizing, the hexagonal ferrite particle powder of Comparative Example 1 was obtained. Table 1 shows various properties of the obtained hexagonal ferrite particle powder.
比較例２：
ＢａＣｌ２・２Ｈ２Ｏ ０．０７５ｍｏｌ、ＦｅＣｌ３・６Ｈ２Ｏ ０．６０ｍｏｌ、ＴｉＣｌ４ ０．０３ｍｏｌ、ＣｏＣｌ２ ０．０３ｍｏｌを１Ｌの水に溶解し、得られた溶液を、２．８ｍｏｌの水酸化ナトリウムを溶解した１Ｌの水酸化ナトリウム水溶液に加えて攪拌した。次いで、該懸濁液を１日間熟成した後、オートクレーブを用いて２５０℃で４時間反応を行い六方晶フェライト粒子の前駆体を得た。
Comparative Example 2:
BaCl 2 · 2H 2 O 0.075 mol, FeCl 3 · 6H 2 O 0.60 mol, TiCl 4 0.03 mol, CoCl 2 0.03 mol were dissolved in 1 L of water, and the resulting solution was dissolved in 2.8 mol of water. The mixture was added to 1 L aqueous sodium hydroxide solution in which sodium oxide was dissolved and stirred. Next, the suspension was aged for 1 day, and then reacted at 250 ° C. for 4 hours using an autoclave to obtain a precursor of hexagonal ferrite particles.
次に、得られた六方晶フェライト粒子の前駆体を含む反応溶液を、純水を用いて洗液のｐＨ値が８以下になるまで十分に水洗した後、六方晶フェライト粒子の前駆体の懸濁液を調製し、上澄み液を除去した後、該懸濁液中にフラックスとして５００ｇのＮａＣｌを添加して攪拌し、ＮａＣｌを溶解させた。次に、溶解したＮａＣｌを含む六方晶フェライト粒子の前駆体の懸濁液を面積の広いバットに入れ、乾燥機で１００℃に加熱して、水分を蒸発させた。 Next, the reaction solution containing the obtained hexagonal ferrite particle precursor is sufficiently washed with pure water until the pH value of the washing solution becomes 8 or less, and then the suspension of the hexagonal ferrite particle precursor is suspended. After preparing a turbid liquid and removing the supernatant, 500 g of NaCl was added to the suspension as a flux and stirred to dissolve the NaCl. Next, a suspension of the hexagonal ferrite particle precursor containing dissolved NaCl was placed in a vat with a wide area and heated to 100 ° C. with a dryer to evaporate the water.
次いで、得られた六方晶フェライト粒子の前駆体とＮａＣｌの混合物を解砕し、坩堝に入れ、まず８３０℃で２０分間加熱してＮａＣｌを融解し、次に、温度を８００℃まで下げ、８００℃で約１０時間加熱処理し、その後、室温まで冷却した。次に、水洗によりＮａＣｌを除去し、ろ過・乾燥・粉砕して、比較例２の六方晶フェライト粒子粉末を得た。得られた六方晶フェライト粒子粉末の諸特性を表１に示す。 The resulting hexagonal ferrite particle precursor and NaCl mixture is then crushed and placed in a crucible and first heated at 830 ° C. for 20 minutes to melt NaCl, then the temperature is lowered to 800 ° C. It heat-processed at 10 degreeC for about 10 hours, and cooled to room temperature after that. Next, NaCl was removed by washing with water, followed by filtration, drying and pulverization to obtain hexagonal ferrite particle powder of Comparative Example 2. Table 1 shows various properties of the obtained hexagonal ferrite particle powder.
＜磁気テープの製造＞
磁気テープ１〜６、比較磁気テープ１及び２：
六方晶フェライト粒子粉末の種類を種々変化させた以外は、前記実施例の磁気テープの作製方法に従って磁気テープを製造した。
<Manufacture of magnetic tape>
Magnetic tapes 1-6, comparative magnetic tapes 1 and 2:
A magnetic tape was manufactured according to the magnetic tape manufacturing method of the above example, except that the type of hexagonal ferrite particle powder was variously changed.
得られた磁気テープの諸特性を表２に示す。 Table 2 shows the characteristics of the obtained magnetic tape.
上記実施例より、本発明によって得られた六方晶フェライト粒子粉末は、平均板面径が１０〜３０ｎｍであり、ＡＦｅ１２Ｏ１９で表されるマグネトプランバイト型フェライト粒子粉末のＦｅの置換元素としてＴｉ及びＡｌを用いることによって、磁性不純物を低減し、粉体ＳＦＤを低減することができるので、これらを用いて得られた磁気記録媒体（磁気テープ１〜３，５，６）は、ノイズがより低減され、高いＣ／Ｎが得られている。 From the above examples, the hexagonal ferrite particle powder obtained by the present invention has an average plate surface diameter of 10 to 30 nm, and is used as a substitution element for Fe in the magnetoplumbite type ferrite particle powder represented by AFe 12 O 19. By using Ti and Al, magnetic impurities can be reduced and the powder SFD can be reduced. Therefore, the magnetic recording media (magnetic tapes 1 to 3, 5, 6) obtained using these have noise. It is further reduced and a high C / N is obtained.
本発明に係る磁気記録媒体用六方晶フェライト粒子粉末は、平均板面径が１０〜３０ｎｍ、粉体ＳＦＤが１．５以下であり、一般式ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）から成ることにより磁性不純物が生成しにくいことにより、磁気記録媒体のノイズをより低減できるため、高密度磁気記録媒体の磁性粒子粉末として好適である。
The hexagonal ferrite particle powder for magnetic recording media according to the present invention has an average plate surface diameter of 10 to 30 nm, a powder SFD of 1.5 or less, and a general formula AFe 12-x / 2-2y / 3 Ti x Al. Since magnetic impurities are less likely to be generated by comprising y O 19 (A: one or more elements selected from Ba, Sr, and Ca), noise of the magnetic recording medium can be further reduced. Suitable as magnetic particle powder.
Claims (3)
ＡＦｅ１２−ｘ／２−２ｙ／３ＴｉｘＡｌｙＯ１９
（Ａ：Ｂａ，Ｓｒ及びＣａから選ばれる１種以上の元素）
（ｘ：０．０５〜３、ｙ：０．１〜３） A hexagonal ferrite particle powder for magnetic recording media, comprising a magnetoplumbite type ferrite particle powder represented by the following general formula, having an average plate surface diameter of 10 to 30 nm and a powder SFD of 1.5 or less .
AFe 12-x / 2-2y / 3 Ti x Al y O 19
(A: one or more elements selected from Ba, Sr and Ca)
(X: 0.05~3, y: 0.1 ~3)
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