JPH09232123A - Hexagonal system ferrite magnetic powder - Google Patents
Hexagonal system ferrite magnetic powderInfo
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- JPH09232123A JPH09232123A JP8033548A JP3354896A JPH09232123A JP H09232123 A JPH09232123 A JP H09232123A JP 8033548 A JP8033548 A JP 8033548A JP 3354896 A JP3354896 A JP 3354896A JP H09232123 A JPH09232123 A JP H09232123A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は塗布型の磁気記録媒
体に用いられる磁性粉に係わり、さらに詳しくは、光透
過型サーボ方式の磁気記録媒体に適した六方晶系フェラ
イト磁性粉に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic powder used in a coating type magnetic recording medium, and more particularly to a hexagonal ferrite magnetic powder suitable for a light transmissive servo type magnetic recording medium.
【０００２】[0002]
【従来の技術】一軸磁気異方性を有する六方晶系フェラ
イト磁性粉を樹脂バインダとともに基体上に塗布して成
る塗布型磁気記録媒体は、高密度な磁気記録に適し、環
境安定性、走行耐久性や生産性にもすぐれた磁気記録媒
体として知られている。このような磁性粉として用いら
れる六方晶系フェライトは、通常、鉄原子の一部を適当
な金属元素で置換することにより、磁気記録に適するよ
うに保磁力を低減化されて使用される。2. Description of the Related Art A coating type magnetic recording medium prepared by coating hexagonal ferrite magnetic powder having uniaxial magnetic anisotropy with a resin binder on a substrate is suitable for high density magnetic recording, environmental stability and running durability. It is known as a magnetic recording medium excellent in productivity and productivity. The hexagonal ferrite used as such magnetic powder is usually used by reducing a coercive force suitable for magnetic recording by substituting a part of iron atoms with an appropriate metal element.
【０００３】このような六方晶系フェライトのなかで
も、Ｍ型（Magnetoplumbite type）の六方晶系フェライ
ト微粒子は、飽和磁化量が５５〜６０ｅｍｕ／ｇ程度と
比較的低いのにもかかわらず、それを用いて作製した磁
気記録媒体は、線記録密度向上が容易であるだけでな
く、出力、とりわけ０．７μｍ以下の短波長出力がすぐ
れていることが知られている。このことは、以下の理由
に因ると考えられる。すなわち、Ｍ型六方晶系フェライ
ト微粒子においては、磁化反転分布（ＳＦＤ）や粒度分
布の幅が狭く急峻であること、また、微粒子表面にはア
ルカリイオンであるＢａ2+、Ｓｒ2+、あるいはＰｂ2+な
どが酸吸着サイトとして存在するため、通常の磁気記録
媒体で多用される酸性系樹脂バインダとの相互作用が大
きく、したがって磁性塗料調製時に分散状態が良好とな
り、その結果、磁性体が高度に充填され表面性の良好な
磁性層を備えた磁気記録媒体が得られることなどに、起
因している。なお、ＳＦＤは磁性粉の保磁力分布を表す
もので、高密度記録達成のためには、これをできるだけ
小さくすることが求められている。Among such hexagonal ferrites, the M-type (Magnetoplumbite type) hexagonal ferrite fine particles have a relatively low saturation magnetization of about 55 to 60 emu / g, but It is known that the magnetic recording medium produced by using the magnetic recording medium is not only easy to improve the linear recording density, but also has excellent output, especially short wavelength output of 0.7 μm or less. This is considered to be due to the following reasons. That is, in the M-type hexagonal ferrite fine particles, the width of the magnetization reversal distribution (SFD) and the particle size distribution is narrow and steep, and the surface of the fine particles has alkali ions of Ba 2+ , Sr 2+ , or Pb. Since 2+ exists as an acid adsorption site, it interacts strongly with the acidic resin binder that is often used in ordinary magnetic recording media, and therefore the dispersion state is good during the preparation of the magnetic coating, which results in a high degree of magnetic properties. This is due to the fact that it is possible to obtain a magnetic recording medium that is filled with the magnetic recording medium and has a magnetic layer having a good surface property. The SFD represents the coercive force distribution of the magnetic powder, and it is required to make it as small as possible in order to achieve high density recording.
【０００４】このような特長を有するＭ型六方晶系フェ
ライトは、元来、結晶構造上自由電子が存在しないの
で、他の磁性微粒子よりも光透過係数が大きい材料であ
ることが知られている。したがって、Ｍ型六方晶系フェ
ライト微粒子を用いた塗膜は、メタル微粒子あるいはマ
グネタイト微粒子を塗布して得られる磁性膜に比べて良
好な光透過性を示す。このため、Ｍ型六方晶系フェライ
トを用いた磁気記録媒体は、線記録密度向上が可能なだ
けでなく、光サーボ技術とくに光透過型サーボ技術を導
入することによってトラック・ピッチも狭化可能になる
ため、高い面密度での情報の記録再生が可能になると期
待されている。It is known that the M-type hexagonal system ferrite having such characteristics has a light transmission coefficient larger than that of other magnetic fine particles because it has no free electrons due to its crystal structure. . Therefore, the coating film using the M-type hexagonal ferrite fine particles exhibits better light transmittance than the magnetic film obtained by coating the metal fine particles or the magnetite fine particles. Therefore, the magnetic recording medium using the M-type hexagonal ferrite can not only improve the linear recording density but also narrow the track pitch by introducing the optical servo technology, especially the light transmission type servo technology. Therefore, it is expected that information can be recorded / reproduced with high areal density.
【０００５】ところで、磁気記録媒体において十分な耐
久性や信頼性を示すようにするためには、磁性層表面が
適度の電気伝導性を有していることが必要である。磁性
面の電導性が低い場合には、媒体が走行・回転時などに
摩擦により帯電し、電荷を保持し続けるため、周囲のゴ
ミを静電的に吸いよせてしまう。このため、ヘッド・媒
体間隔が広がり十分な信号の書き込みができない、再生
信号が欠落するといった不具合が発生するばかりか、ゴ
ミの種類によっては、ヘッドクラッシュや媒体損傷など
の事故の原因になる。このような現象を防止するため、
磁性層には酸化錫、酸化チタン、カーボンブラックなど
の半導体微粒子を添加して、適度の導電性を与えてい
る。媒体の線記録密度が高くなればなるほどこの機構に
よる信号消失率が増大するので、高密度記録を指向する
場合、磁性面に導電性をいかにして与え電荷を速やかに
緩和させるかということは、重要な課題となっている。By the way, in order to show sufficient durability and reliability in the magnetic recording medium, it is necessary that the surface of the magnetic layer has an appropriate electric conductivity. When the magnetic surface has a low electrical conductivity, the medium is charged by friction during running and rotation and continues to retain the electric charge, so that the surrounding dust is electrostatically absorbed. As a result, the distance between the head and the medium is widened, and a sufficient signal cannot be written, a reproduced signal is lost, and depending on the type of dust, an accident such as head crash or medium damage may occur. To prevent such a phenomenon,
Semiconductor magnetic particles such as tin oxide, titanium oxide, and carbon black are added to the magnetic layer to impart appropriate conductivity. The higher the linear recording density of the medium, the higher the signal loss rate due to this mechanism. Therefore, when aiming for high-density recording, how to impart conductivity to the magnetic surface and quickly alleviate the electric charge is It has become an important issue.
【０００６】[0006]
【発明が解決しようとする課題】ところで、磁性面に導
電性を付与するために添加されるこれらの半導体微粒子
は、一般に、自由電子をもつため光吸収性が高いことが
知られている。したがって、上記したＭ型六方晶系フェ
ライトを用いた磁気記録媒体において、添加されたこれ
らの半導体微粒子は、磁性膜の光透過性を阻害すること
になる。たとえば、磁性材料として光吸収係数の小さい
公知のＭ型六方晶系フェライト微粒子を用いた磁性層の
場合、信頼性確保のため半導体微粒子を添加すると、媒
体の光透過性が損なわれサーボＳ／Ｎ比が極端に低下し
てしまう。そこで、半導体微粒子を添加しても媒体の光
透過性が確保されるようにと、磁性層をできるだけ薄く
するという試みもなされている。しかしながら、磁性膜
厚が薄くなると、膜の擦過性が悪くなりヘッドとの摺動
で磁性層が傷つきやすくなってしまう。By the way, it is known that these semiconductor fine particles, which are added to impart conductivity to the magnetic surface, generally have high light absorption because they have free electrons. Therefore, in the magnetic recording medium using the above-mentioned M-type hexagonal ferrite, the added semiconductor fine particles impede the light transmittance of the magnetic film. For example, in the case of a magnetic layer using well-known M-type hexagonal ferrite fine particles having a small light absorption coefficient as a magnetic material, if semiconductor fine particles are added to ensure reliability, the optical transmissivity of the medium is impaired and the servo S / N ratio is reduced. The ratio becomes extremely low. Therefore, attempts have been made to make the magnetic layer as thin as possible so that the optical transparency of the medium can be ensured even if the semiconductor fine particles are added. However, when the magnetic film thickness is reduced, the scratching property of the film is deteriorated and the magnetic layer is easily scratched by sliding with the head.
【０００７】また、磁性膜の光透過性を阻害する他の要
因の一つとして、磁性体自体の光反射があげられる。磁
性膜に入射させる光の一部分が磁性体によって反射され
ると、媒体に入射する光量は当然のことながら減少す
る。したがって、反射率が高い場合には、透過率そのも
のは高くとも媒体を透過する光量は減少することになる
ので、透過率が低い場合と同じ結果になってしまう。[0007] Another factor that impedes the optical transparency of the magnetic film is the optical reflection of the magnetic material itself. When a part of the light incident on the magnetic film is reflected by the magnetic material, the amount of light incident on the medium naturally decreases. Therefore, when the reflectance is high, the amount of light transmitted through the medium is reduced even if the transmittance itself is high, and the result is the same as when the transmittance is low.
【０００８】したがって、Ｍ型六方晶系フェライトを磁
性体として用いた光透過型サーボ方式による磁気記録媒
体において、信頼性を維持し記録密度を向上させるため
には、磁性膜厚を薄くすることなく光透過率をさらに向
上させ得る磁性体、いいかえれば光の反射率と吸収率が
共に小さい磁性体が求められていた。Therefore, in order to maintain the reliability and improve the recording density in the magnetic recording medium by the light transmission servo system using the M-type hexagonal ferrite as the magnetic material, it is necessary to reduce the magnetic film thickness. There has been a demand for a magnetic material capable of further improving the light transmittance, in other words, a magnetic material having both small light reflectance and light absorption.
【０００９】本発明は上記の事情を鑑みてなされたもの
であり、光の反射率と吸収率を共に小さくすることによ
り光透過率を向上させた磁性体を提供することを、その
目的としている。The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic body having an improved light transmittance by reducing both the reflectance and the absorptance of light. .
【００１０】[0010]
【課題を解決するための手段】本発明の六方晶系フェラ
イト磁性粉は、一般式 ＰｂＯ・Ｆｅ12-xＭ1 x Ｏ18 （ただし、Ｍ1 は原子数平均価数が３価になるように調
節された保磁力低減化のための原子群を表す。）で示さ
れ、光の反射率が１０％以下、光吸収係数が１．１×１
０3 ／ｃｍ以下であることを特徴としている。The hexagonal ferrite magnetic powder of the present invention has a general formula of PbO.Fe 12 -x M1 x O 18 (wherein M1 is adjusted so that the average valence of atoms is trivalent). Represents the atomic group for reducing the coercive force, and has a light reflectance of 10% or less and a light absorption coefficient of 1.1 × 1.
It is characterized in that it is 0 3 / cm or less.
【００１１】本発明においては、光の反射率は１０％以
下が望ましく、より好ましくは８％以下である。光の反
射率が１０％を越える場合には、十分な光が磁性体中に
入らなくなり光量の不足を招くため、光サーボ方式には
適さなくなる。本発明において、光吸収係数は１．１×
１０3 ／ｃｍ以下が望ましく、より好ましくは０．９×
１０3 ／ｃｍ以下である。光吸収係数が１．１×１０3
／ｃｍを越える場合には、媒体中を光が十分透過するこ
とができなくなり、やはり光サーボ方式には適さなくな
るため、好ましくない。また、本発明の六方晶系フェラ
イト磁性粉において、光の反射率は１０％以下、光吸収
係数は１．１×１０3 ／ｃｍ以下で共に小さいほど好ま
しいが、Ｍ型構造では、通常、フォノン吸収の寄与もあ
り、光吸収係数は２００／ｃｍより小さい値をとること
が難しい。In the present invention, the light reflectance is preferably 10% or less, more preferably 8% or less. If the light reflectance exceeds 10%, sufficient light does not enter the magnetic substance, causing a shortage of the light amount, which is not suitable for the optical servo system. In the present invention, the light absorption coefficient is 1.1 ×
10 3 / cm or less is desirable, more preferably 0.9 ×
It is 10 3 / cm or less. Light absorption coefficient is 1.1 × 10 3
If it exceeds / cm, light cannot be sufficiently transmitted through the medium, which is not suitable for the optical servo system, which is not preferable. Further, in the hexagonal ferrite magnetic powder of the present invention, the light reflectance is 10% or less, and the light absorption coefficient is 1.1 × 10 3 / cm or less, both of which are preferable. However, in the M-type structure, phonons are usually used. Because of the contribution of absorption, it is difficult for the light absorption coefficient to take a value smaller than 200 / cm.
【００１２】本発明において磁性粉を特徴づける光の反
射率と吸収係数は、以下のように定義される。まず、当
該磁性粉と同組成の六方晶系フェライト単結晶をフラッ
クス法で育成し、その単結晶に対して、波長８５０ｎｍ
の光の反射率と透過率を室温において測定する。そし
て、その測定値と試料厚みから、光の反射率と吸収係数
を算出する。ここで、光の反射率と吸収係数の数値を波
長８５０ｎｍの光に対するもので代表させているのは、
この波長が、ＬＤ発振波長であり実用ドライブに用いら
れているという理由に因る。また、多結晶粉末である磁
性粉そのものを用いず、あえて単結晶を用いて光の反射
率と吸収係数を求めるようにしたのは、磁性粉の場合に
は、組成が同一であっても、粒子のサイズや配列状態な
ど組成以外の複合的因子によって透過率の測定値が影響
を受けるため、組成と反射や吸収との間に明確な相関が
みられなくなるからである。The light reflectance and absorption coefficient which characterize the magnetic powder in the present invention are defined as follows. First, a hexagonal ferrite single crystal having the same composition as that of the magnetic powder is grown by a flux method, and the single crystal has a wavelength of 850 nm.
The reflectance and transmittance of the light are measured at room temperature. Then, the light reflectance and absorption coefficient are calculated from the measured values and the sample thickness. Here, the numerical values of the reflectance and the absorption coefficient of light are represented by those for light having a wavelength of 850 nm.
This is because this wavelength is the LD oscillation wavelength and is used in a practical drive. Further, instead of using the magnetic powder itself which is a polycrystalline powder, the purpose of determining the reflectance and absorption coefficient of light by using a single crystal is that, in the case of magnetic powder, even if the composition is the same, This is because the measured value of the transmittance is affected by complex factors other than the composition such as the size and arrangement state of the particles, and a clear correlation between the composition and the reflection or absorption cannot be seen.
【００１３】本発明において、磁性粉の保磁力は３００
〜３０００ Ｏｅの範囲にあることが望ましい。３００
Ｏｅ以下の場合記録減磁が著しく高密度記録に適さな
くなり、逆に保磁力が３０００ Ｏｅ以上の場合には、
一般的な磁気ヘッドでは飽和を起こしてしまいこれを十
分に磁化させることができない。In the present invention, the coercive force of the magnetic powder is 300.
It is desirable to be in the range of ~ 3000 Oe. 300
When it is less than Oe, the recording demagnetization is remarkably unsuitable for high-density recording.
A general magnetic head causes saturation and cannot be magnetized sufficiently.
【００１４】保磁力を上記範囲に制御するために、上記
フェライトの一般式においてＦｅの一部は適当な金属元
素で置換されている。この際、置換イオンの価数が原子
数平均３価になるようにすることが望ましい。たとえば
置換元素の中に２価金属が含まれる場合には、４価、５
価、６価元素を併用して置換元素の価数が原子数平均３
価になるように調節する。In order to control the coercive force within the above range, part of Fe in the above general formula of ferrite is replaced with an appropriate metal element. At this time, it is desirable that the valence of the substituted ion be trivalent on average. For example, when the substitutional element contains a divalent metal, it is tetravalent or 5
The valence of the substitutional element is 3 when the valence and hexavalent elements are used together.
Adjust to the value.
【００１５】本発明の磁性粉においては、このような置
換元素の中に、III ａ族元素およびIII ｂ族元素の中か
ら選ばれる少なくとも１種の元素が含まれる。すなわ
ち、本発明の磁性粉は、構成元素であるＦｅの一部が、
III ａ族元素およびIII ｂ族元素の中から選ばれる少な
くとも１種の元素により置換されていることを、その第
２の特徴としている。In the magnetic powder of the present invention, at least one element selected from the group IIIa element and the group IIIb element is contained in such a substitution element. That is, in the magnetic powder of the present invention, a part of Fe, which is a constituent element,
The second characteristic is that at least one element selected from the group IIIa elements and the group IIIb elements is substituted.
【００１６】周期表III ａ族元素およびIII ｂ族元素
は、その電子構造上オープンなｄシェルをもたないた
め、正４面***置あるいは正８面***置に入っても、遷
移元素のように***幅が光エネルギーに相当する結晶場
エネルギー***（***幅１０Ｄｑ〜２００００ｃｍ-1）
を起こさない。したがって、光学的には透明である。Since the Group IIIa elements and Group IIIb elements of the periodic table do not have an open d-shell due to their electronic structure, even if they enter the tetrahedral position or the octahedral position, they are split like transition elements. Crystal field energy splitting whose width corresponds to light energy (splitting width 10 Dq to 20000 cm -1 ).
Do not wake up. Therefore, it is optically transparent.
【００１７】さらにいえば、本発明に係わる置換元素は
元々３価のＦｅを置換するためのものであるから、３価
元素であるIII ａ族元素およびIII ｂ族元素を置換元素
として導入した場合、置換サイトでは局所的な価数補償
が保たれている。このために置換サイトは光学的には不
活性となる。これに対して、たとえば２価と４価の元素
を導入する場合、各々の原子サイトでの価数補償は破
れ、エキシトンのトラップセンターとなるため、色が着
き透過率は低下する。したがってIII ａ族、IIIｂ族元
素の導入量が多くなるにつれ磁性体は透明性を増す。導
入に際しては、その導入量が、磁性粉の保磁力や磁化量
に影響を与えるので、磁気記録に適した保磁力や磁化量
を得るためには、適切な範囲内に導入量を制御すること
が必要である。Furthermore, since the substituting element according to the present invention is originally for substituting trivalent Fe, when the trivalent elements IIIa group element and IIIb group element are introduced as substitution elements. , Local valence compensation is maintained at the replacement site. Therefore, the substitution site is optically inactive. On the other hand, for example, when a divalent or tetravalent element is introduced, the valence compensation at each atomic site is broken and it becomes an exciton trap center, which causes coloration and lowers the transmittance. Therefore, the transparency of the magnetic substance increases as the introduction amount of the IIIa group and IIIb group elements increases. At the time of introduction, the amount of introduction affects the coercive force and the amount of magnetization of the magnetic powder. Therefore, in order to obtain the coercive force and the amount of magnetization suitable for magnetic recording, the amount of introduction should be controlled within an appropriate range. is required.
【００１８】本発明に使用可能なIII ａ族元素として
は、Ｂ、Ａｌ、Ｇａ、Ｉｎ、およびＴｌがあげられ、II
I ｂ族元素としては、Ｓｃ、Ｙ、およびランタン系列元
素とアクチニウム系列元素があげられる。置換に際して
は元素種固有の置換サイトが存在する。このことを反映
して、置換元素の違いによってさまざまな磁気特性の粉
末が得られる。たとえばΙｎやＳｃはＭ型マグネトプラ
ンバイトの主要な磁気異方性を決めるＲ層の４ｅサイト
に好んではいるため、これらにより置換した場合には、
結晶の異方性を小さくし、保磁力を下げる。一方、Ａｌ
やＧａなどは異方性を大きくする傾向がある。元素の選
択・組み合わせ・配合比率は無数にあり、導入量の適正
範囲も元素の選択・組み合わせによって、それぞれ異な
ってくる。したがって、必要とされる保磁力や磁化量に
あわせて、置換元素の種類やその導入量を適宜選択する
ことが望ましい。Group IIIa elements that can be used in the present invention include B, Al, Ga, In, and Tl.
Examples of Group Ib elements include Sc, Y, and lanthanum series elements and actinium series elements. Upon substitution, there is a substitution site unique to the element species. Reflecting this, powders with various magnetic properties can be obtained depending on the difference in the substitution element. For example, Ιn and Sc are preferred for the 4e site of the R layer that determines the main magnetic anisotropy of the M-type magnetoplumbite.
It reduces the crystal anisotropy and lowers the coercive force. On the other hand, Al
And Ga tend to increase anisotropy. There are innumerable selections, combinations, and blending ratios of elements, and the appropriate range of introduction amount also differs depending on the selection and combination of elements. Therefore, it is desirable to appropriately select the type of substitution element and the amount of introduction thereof according to the required coercive force and the amount of magnetization.
【００１９】なお、本発明において、３価元素である上
記III ａ族元素およびIII ｂ族元素と併用可能な置換元
素として、２価元素であるＭｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃ
ｕ、Ｚｎ、Μｇ、Ｃｄなどが例示され、３価元素として
はＲｈなど、４価元素としてはＴｉ、Ｚｒ、Ｈｆ、Ｓ
ｎ、Ｇｅ、Ｔｅ、Ｒｕなど、５価元素としてはＶ、Ｎ
ｂ、Ｔａ、Ｂｉ、Ｓｂなど、６価元素としてはＭｏ、Ｗ
などが例示される。In the present invention, divalent elements such as Mn, Fe, Co, Ni and C are used as substitution elements which can be used in combination with the above-mentioned trivalent element group IIIa element and group IIIb element.
u, Zn, Mg, Cd, etc. are exemplified, Rh is used as a trivalent element, and Ti, Zr, Hf, S are used as a tetravalent element.
V, N as pentavalent elements such as n, Ge, Te and Ru
Hexavalent elements such as b, Ta, Bi and Sb are Mo and W.
And the like.
【００２０】本発明においては、磁性粉の室温での磁化
量が４０〜７５ｅｍｕ／ｇの範囲にあることが望まし
い。４０ｅｍｕ／ｇ以下の磁化量では作製した媒体の長
波長出力が不足をきたす。また、７５ｅｍｕ／ｇ以上の
磁化量は、Ｍ型構造であって磁気記録に適した粒径であ
るという条件下では、達成できないものである。In the present invention, the amount of magnetization of the magnetic powder at room temperature is preferably in the range of 40 to 75 emu / g. If the magnetization amount is 40 emu / g or less, the long wavelength output of the manufactured medium becomes insufficient. Further, a magnetization amount of 75 emu / g or more cannot be achieved under the condition that it has an M-type structure and a particle size suitable for magnetic recording.
【００２１】本発明において、磁性粉の平均粒径は２０
〜１００ｎｍの範囲であることが望ましく、さらに好ま
しくは２０〜６０ｎｍの範囲である。１００ｎｍ以上の
粒径では粒度分布が広がり、媒体を作製したときにノイ
ズ成分が増大することが確認されており、本発明の意図
する高密度記録には適さなくなる。２０ｎｍ以下の粒径
では、個々の粒子体積が小さいため、磁気モーメントの
方向が磁化容易軸から外れて絶えず揺動し、磁性粉群の
見かけ上の磁化が消失するという、いわゆるスーパーパ
ラ的に振る舞うようになり、磁気記録には適さなくな
る。In the present invention, the average particle size of the magnetic powder is 20.
˜100 nm is desirable, and more preferably 20 to 60 nm. It has been confirmed that when the particle diameter is 100 nm or more, the particle size distribution is widened and the noise component is increased when the medium is manufactured, which is not suitable for the high density recording intended by the present invention. At a particle size of 20 nm or less, since the volume of each particle is small, the direction of the magnetic moment deviates from the axis of easy magnetization and constantly fluctuates, and the apparent magnetization of the magnetic powder group disappears. As a result, it becomes unsuitable for magnetic recording.
【００２２】本発明の磁性粉は、上記の粒径、形状の範
囲内にあって、かつ、比表面積はＢＥＴ法による値で２
５〜７０ｍ2 ／ｇの範囲にあることが望ましい。好まし
い比表面積がこのように限定されるのは、比表面積が、
媒体製造にあたり磁性塗料を調製する際、磁性粒子が樹
脂バインダと相互作用する度合いに密接に関連する量で
あるためである。すなわち２５ｍ2 ／ｇ以下では、樹脂
バインダから受ける抵抗が少なくなって磁性粉の配向性
は向上するものの、磁性塗料中の磁性粉の分散安定性の
確保が困難になり、一方、７０ｍ2 ／ｇ以上では磁性粉
の配向性・充填性が低下し、高密度記録に適さなくな
る。The magnetic powder of the present invention has a particle size and shape within the above range, and has a specific surface area of 2 by the BET method.
It is desirably in the range of 5 to 70 m 2 / g. The preferred specific surface area is thus limited because the specific surface area is
This is because the amount is closely related to the degree of interaction of the magnetic particles with the resin binder when the magnetic coating material is prepared for producing the medium. That is, at 25 m 2 / g or less, the resistance received from the resin binder is reduced and the orientation of the magnetic powder is improved, but it is difficult to secure the dispersion stability of the magnetic powder in the magnetic paint, while at 70 m 2 / g If the above conditions are satisfied, the orientation and filling of the magnetic powder will deteriorate, making it unsuitable for high-density recording.
【００２３】本発明において磁性粉の板状比は、媒体中
の充填性、配向性を勘案すると２〜９の範囲内であるこ
とが望ましく、さらに好ましくは３〜６の範囲である。
板状比が大きくなるにしたがい、配向性の向上や磁化反
転分布（ＳＦＤ）の急峻化が見られるが、充填性は逆に
低下する。再生出力を増大させるには充填性、配向性の
向上，ＳＦＤの急峻化のバランスを取ることが重要であ
り、それらを勘案した結果上記範囲が好ましいとされる
に至った。In the present invention, the plate ratio of the magnetic powder is preferably in the range of 2 to 9 in view of the filling property and orientation in the medium, and more preferably in the range of 3 to 6.
As the plate ratio increases, the orientation is improved and the magnetization switching distribution (SFD) is sharpened, but the filling property is decreased. In order to increase the reproduction output, it is important to balance the filling property, the orientation, and the steepness of the SFD, and as a result of considering them, the above range has been considered preferable.
【００２４】このように、本発明の六方晶系フェライト
磁性粉においては、元素の電子構造や置換サイトでの光
学活性度合いを勘案し、アルカリイオンとしてＰｂ2+を
含み、フェライトを構成するＦｅの一部を置換する置換
元素として、III ａ族元素、III ｂ族元素から選ばれる
少なくとも１種の元素が含まれるようにすることによっ
て、１０％以下という光の反射率と同時に１×１０3 ／
ｃｍ以下という光吸収係数を実現させている。As described above, in the hexagonal ferrite magnetic powder of the present invention, in consideration of the electronic structure of the element and the degree of optical activity at the substitution site, Pb 2+ as an alkali ion is contained in the Fe, which constitutes ferrite. By including at least one element selected from the group IIIa element and the group IIIb element as a substituting element for substituting a part of the element, the light reflectance of 10% or less and 1 × 10 3 /
The light absorption coefficient of cm or less is realized.
【００２５】本発明の磁性粉は、光の反射率と吸収係数
が低いため、作製した媒体の表面反射を抑えるとともに
透過率を高めることができるので、線記録密度をさらに
向上し得る。Since the magnetic powder of the present invention has a low light reflectance and absorption coefficient, it can suppress the surface reflection of the manufactured medium and can increase the transmittance, so that the linear recording density can be further improved.
【００２６】本発明の磁性粉は、たとえばガラス結晶化
法などの六方晶系フェライトの通常の製法によって得る
ことが可能である。The magnetic powder of the present invention can be obtained by a conventional method for producing hexagonal ferrite such as a glass crystallization method.
【００２７】[0027]
【発明の実施の形態】以下、本発明の実施の形態を実施
例にしたがって説明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to examples.
【００２８】実施例１ 一般式 ＰｂＯ・Ｆｅ12-2x-y Ｃｏx Ｔｉx Ｍ2 y Ｏ18 （ただし、Ｍ2 はIII ａ族元素およびIII ｂ族元素の中
から選択される少なくとも１種の元素を表す）で示され
る六方晶系フェライトについて、ｘ＝０．７０、Ｍ2 ＝
Ａｌ、ｙ＝１．０として、単結晶と磁性粉とを作製し
た。Example 1 General formula PbO.Fe 12-2x-y Co x Ti x M 2 y O 18 (wherein M 2 is at least one element selected from the IIIa group element and the IIIb group element) For a hexagonal ferrite represented by the formula), x = 0.70, M2 =
A single crystal and magnetic powder were produced with Al and y = 1.0.
【００２９】上記組成の単結晶育成は、フラックスとし
てＮａ2 ＣＯ3 を用い、１３００℃を上限とし冷却速度
３℃／ｈとしたフラックス法により行った。The growth of the single crystal having the above composition was performed by a flux method using Na 2 CO 3 as a flux and a cooling rate of 3 ° C./h with an upper limit of 1300 ° C.
【００３０】得られた試料は、５×５ｍｍ2 （００１）
面、厚み１ｍｍ程度であった。吸収係数測定に際して
は、（００１）面を研磨加工し、（００１）面鉛直入射
で波長７００〜９００ｎｍの範囲で透過率を測定した。
測定は、室温で（株）日立社製分光光度計Ｕ３２００を
用いて行った。The obtained sample was 5 × 5 mm 2 (001)
The surface had a thickness of about 1 mm. In measuring the absorption coefficient, the (001) plane was polished, and the transmittance was measured in the wavelength range of 700 to 900 nm at the (001) plane vertical incidence.
The measurement was performed using a spectrophotometer U3200 manufactured by Hitachi, Ltd. at room temperature.
【００３１】上記組成の磁性粉の作製にあたっては、Ｂ
ａＯ−Ｂ2 Ｏ3 をガラス母相としたガラス結晶化法を用
いた。すなわちＢａＯ−Ｂ2 Ｏ3 のガラス母相成分とフ
ェライト成分原料とを良く混合した後、溶融し融液を双
ロールにて急冷した。ガラス母相成分／フェライト成分
の重量比は６５／３５となるようにした。その後熱処理
を施しフェライトをガラス母相中で成長させた。ガラス
母相を除去することによって、本発明の磁性粉であるフ
ェライト微粉末を得た。In producing the magnetic powder having the above composition, B
The aO-B 2 O 3 using a glass crystallization method using glass matrix. That was well mixed and the glass matrix component and a ferrite component material of BaO-B 2 O 3, was quenched molten melt with a double roll. The weight ratio of glass matrix component / ferrite component was set to 65/35. Then, heat treatment was performed to grow ferrite in the glass matrix. By removing the glass matrix, ferrite fine powder, which is the magnetic powder of the present invention, was obtained.
【００３２】得られた磁性粉について、磁気特性の測定
は振動試料型磁力計（ＶＳＭ）を用いて行った。保磁力
および磁化量は１０ｋＯｅでの値である。磁性粉の粒径
・形状は２０万倍の透過電子顕微鏡写真像より無作為に
２００個の粒子を選び、その粒径、板厚みを測定して得
られた平均値である。比表面積はＢＥＴ法により求め
た。これらの測定結果は、後出の表１の上段に示されて
いる。The magnetic properties of the obtained magnetic powder were measured using a vibrating sample magnetometer (VSM). The coercive force and the magnetization amount are values at 10 kOe. The particle size and shape of the magnetic powder are average values obtained by randomly selecting 200 particles from a transmission electron micrograph image of 200,000 times, and measuring the particle size and plate thickness. The specific surface area was determined by the BET method. The results of these measurements are shown in the upper part of Table 1 below.
【００３３】実施例２〜６ 上記フェライトの一般式において置換元素Ｍ2 の種類と
その置換量ｙを変えた他は実施例１と同様にして、単結
晶と磁性粉とを作製した。そして、実施例１と同様にし
てその特性を調べた。これらの測定結果を、次の表１の
上段に示した。Examples 2 to 6 Single crystals and magnetic powders were produced in the same manner as in Example 1 except that the kind of the substituting element M2 and the substitution amount y in the general formula of the above ferrite were changed. Then, the characteristics were examined in the same manner as in Example 1. The results of these measurements are shown in the upper part of Table 1 below.
【００３４】[0034]
【表１】 次いで、上記フェライトの一般式において構成元素ある
いは置換量ｙが本発明にしたがわない磁性粉を比較例と
して作製し、実施例と同様にその特性を調べた。これら
の測定結果は、後出の表２の上段に示されている。[Table 1] Next, a magnetic powder in which the constituent element or the substitution amount y in the above general formula of ferrite did not comply with the present invention was prepared as a comparative example, and its characteristics were examined in the same manner as in the example. The results of these measurements are shown in the upper part of Table 2 below.
【００３５】比較例１ 上記フェライトの一般式においてＰｂＯの代わりにＢａ
Ｏを用いた他は、実施例１と同様にして磁性粉を作製し
た。Comparative Example 1 In the general formula of the above ferrite, instead of PbO, Ba was used.
A magnetic powder was produced in the same manner as in Example 1 except that O was used.
【００３６】比較例２ 上記フェライトの一般式においてＰｂＯの代わりにＳｒ
Ｏを用いた他は、実施例１と同様にして磁性粉を作製し
た。Comparative Example 2 Sr was used instead of PbO in the above general formula of ferrite.
A magnetic powder was produced in the same manner as in Example 1 except that O was used.
【００３７】比較例３ 上記フェライトの一般式において、置換元素Ｍ2 の置換
量ｙ＝０とした他は、実施例１と同様にして磁性粉を作
製した。Comparative Example 3 A magnetic powder was produced in the same manner as in Example 1 except that the substitution amount y of the substitution element M2 in the above general formula of ferrite was changed to y = 0.
【００３８】[0038]
【表２】 次いで、このようにして得られた本発明の実施例および
比較例の磁性粉を用いて、下記組成の磁性塗料を調製
し、さらに磁性塗膜を作製してその特性を調べた。＜磁
性塗料組成＞ 磁性粉 １００重量部 極性基含有ウレタン樹脂 ５重量部 極性基含有塩化ビニル樹脂 ５重量部 メチルエチルケトン／シクロヘキサノン／トルエン 混合溶剤 ３００重量部 この磁性塗料調製にあたっては、分散メデイアを用い充
分に分散した。そして膜厚み１μｍ程度になるように、
ポリエステルフィルムの上に無磁界で塗布した。得られ
た塗膜試料は、室温で（株）日立社製分光光度計Ｕ３２
００を用い、波長７００〜９００ｎｍの範囲で反射率お
よび透過率を測定した。これらの測定結果は、表１およ
び表２の下段に併せて示してある。[Table 2] Then, using the magnetic powders of the examples and comparative examples of the present invention thus obtained, magnetic coating materials having the following compositions were prepared, and a magnetic coating film was prepared to examine its characteristics. <Magnetic coating composition> Magnetic powder 100 parts by weight Polar group-containing urethane resin 5 parts by weight Polar group-containing vinyl chloride resin 5 parts by weight Methyl ethyl ketone / cyclohexanone / toluene mixed solvent 300 parts by weight In preparing this magnetic coating material, it is sufficient to use a dispersion medium. Dispersed. And, so that the film thickness is about 1 μm,
It was applied onto a polyester film without a magnetic field. The obtained coating film sample was a spectrophotometer U32 manufactured by Hitachi, Ltd. at room temperature.
00, the reflectance and the transmittance were measured in the wavelength range of 700 to 900 nm. The results of these measurements are also shown at the bottom of Tables 1 and 2.
【００３９】表１および表２からも明らかなように、本
発明の磁性粉によって、光の透過率が高く反射率が低い
という光透過性にすぐれた磁気記録媒体が得られた。As is clear from Tables 1 and 2, the magnetic powder of the present invention provided a magnetic recording medium having a high light transmittance and a low reflectance, which was excellent in light transmittance.
【００４０】[0040]
【発明の効果】以上の説明からも明らかなように、本発
明の磁性粉は光の反射率も吸収率も共に低い光透過性に
すぐれた磁性体であって、光透過型サーボ方式に用いる
塗布型磁気記録媒体用磁性粉として好適である。As is apparent from the above description, the magnetic powder of the present invention is a magnetic material having excellent light transmittance with low light reflectance and absorptance, and is used in the light transmitting servo system. It is suitable as a magnetic powder for a coating type magnetic recording medium.
【００４１】[0041]
Claims (2)
節された保磁力低減化のための原子群を表す。）で示さ
れ、光の反射率が１０％以下、光吸収係数が１．１×１
０3 ／ｃｍ以下であることを特徴とする六方晶系フェラ
イト磁性粉。1. The general formula PbO.Fe 12 -x M1 x O 18 (wherein M1 represents an atomic group for reducing the coercive force, which is adjusted so that the average valence of the atoms becomes trivalent). , The light reflectance is 10% or less, and the light absorption coefficient is 1.1 × 1.
Hexagonal ferrite magnetic powder characterized by having a content of 0 3 / cm or less.
元素およびIII ｂ族元素の中から選ばれる少なくとも１
種の元素により置換されていることを特徴とする特許請
求の範囲請求項１記載の六方晶系フェライト磁性粉。2. A part of Fe, which is a constituent element, is at least 1 selected from a group IIIa element and a group IIIb element.
The hexagonal ferrite magnetic powder according to claim 1, wherein the hexagonal ferrite magnetic powder is substituted with a seed element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03354896A JP3231989B2 (en) | 1996-02-21 | 1996-02-21 | Hexagonal ferrite magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03354896A JP3231989B2 (en) | 1996-02-21 | 1996-02-21 | Hexagonal ferrite magnetic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09232123A true JPH09232123A (en) | 1997-09-05 |
| JP3231989B2 JP3231989B2 (en) | 2001-11-26 |
Family
ID=12389621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03354896A Expired - Lifetime JP3231989B2 (en) | 1996-02-21 | 1996-02-21 | Hexagonal ferrite magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3231989B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020095770A (en) * | 2018-12-06 | 2020-06-18 | Ｄｏｗａエレクトロニクス株式会社 | Hexagonal crystal ferrite magnetic powder |
| WO2021226297A1 (en) * | 2020-05-07 | 2021-11-11 | Rogers Corporation | M-type hexaferrite having a planar anisotropy |
| US11679991B2 (en) | 2019-07-30 | 2023-06-20 | Rogers Corporation | Multiphase ferrites and composites comprising the same |
| US11691892B2 (en) | 2020-02-21 | 2023-07-04 | Rogers Corporation | Z-type hexaferrite having a nanocrystalline structure |
| US11783975B2 (en) | 2019-10-17 | 2023-10-10 | Rogers Corporation | Nanocrystalline cobalt doped nickel ferrite particles, method of manufacture, and uses thereof |
| US11827527B2 (en) | 2019-09-24 | 2023-11-28 | Rogers Corporation | Bismuth ruthenium M-type hexaferrite |
-
1996
- 1996-02-21 JP JP03354896A patent/JP3231989B2/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020095770A (en) * | 2018-12-06 | 2020-06-18 | Ｄｏｗａエレクトロニクス株式会社 | Hexagonal crystal ferrite magnetic powder |
| US11679991B2 (en) | 2019-07-30 | 2023-06-20 | Rogers Corporation | Multiphase ferrites and composites comprising the same |
| US11827527B2 (en) | 2019-09-24 | 2023-11-28 | Rogers Corporation | Bismuth ruthenium M-type hexaferrite |
| US11783975B2 (en) | 2019-10-17 | 2023-10-10 | Rogers Corporation | Nanocrystalline cobalt doped nickel ferrite particles, method of manufacture, and uses thereof |
| US11691892B2 (en) | 2020-02-21 | 2023-07-04 | Rogers Corporation | Z-type hexaferrite having a nanocrystalline structure |
| WO2021226297A1 (en) * | 2020-05-07 | 2021-11-11 | Rogers Corporation | M-type hexaferrite having a planar anisotropy |
| GB2609128A (en) * | 2020-05-07 | 2023-01-25 | Rogers Corp | M-type hexaferrite having a planar anisotropy |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3231989B2 (en) | 2001-11-26 |
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