JP3877924B2 - Magnetic disk substrate polishing composition - Google Patents
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- JP3877924B2 JP3877924B2 JP2000013858A JP2000013858A JP3877924B2 JP 3877924 B2 JP3877924 B2 JP 3877924B2 JP 2000013858 A JP2000013858 A JP 2000013858A JP 2000013858 A JP2000013858 A JP 2000013858A JP 3877924 B2 JP3877924 B2 JP 3877924B2
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Description
【０００１】
本発明は磁気ディスク基板研磨用組成物に関し、さらに詳しくは、磁気ヘッドが低浮上量で飛行するのに適した精度の高い磁気ディスク表面が得られる磁気ディスク基板研磨用組成物に関する。
【０００２】
【従来の技術】
コンピューターやワードプロセッサーの外部記憶装置の中で高速でアクセス出来る手段として磁気ディスク（メモリーハードディスク）が広く使われている。この磁気ディスクの代表的な一例は、Ａｌ合金基板の表面にＮｉＰを無電解メッキしたものを基板とし、この基板を表面研磨した後、Ｃｒ合金下地膜、Ｃｏ合金磁性膜そしてカーボン保護膜を順次スパッターで形成したものである。
磁気ディスク表面に磁気ヘッド浮上量以上の高さを有する突起が残っていると、所定高さにて浮上しながら高速で飛行する磁気ヘッドがその突起に衝突して損傷する原因になる。また、磁気ディスク基板に突起や研磨傷などがあるとＣｒ合金下地膜やＣｏ合金磁性膜などを形成したとき、それらの膜の表面に突起が現れ、また研磨傷に基づく欠陥が生じ、磁気ディスク表面が精度の高い平滑面にならないので、ディスク表面の精度を上げるには基板を精密に研磨する必要がある。
【０００３】
このため、磁気ディスク基板の研磨において、突起物をなくし、またはその高さをできるだけ低くし、かつ研磨傷が生じ難い研磨用組成物として多くのものが提案されてきた。なかでも特開平１０−１２１０３５（チタニアに硝酸アルミニウムを添加してなる組成物を使用）はサブミクロンの酸化チタニウム粒子を砥粒として使用しているので従来に比較して高い面精度、研磨速度は達成しやすいが、最近求められる面精度のレベルには砥粒物質の硬度の影響で達成が困難な状況である。また、特開平１１−１６７７１５（コロイダルシリカに硝酸アルミニウムを添加してなる組成物を使用）は砥粒に硬度の小さい酸化ケイ素微粒子を使用しているため面精度は得られやすいが、実生産に使用できる研磨速度の達成が困難であった。
【０００４】
【発明が解決しようとする課題】
高密度磁気記録を可能とするアルミニウム磁気ディスク基板研磨用組成物に要求される品質は、ヘッドの低浮上を可能とする高精度ディスク面の達成である。
本発明の目的は、磁気ディスクの表面粗さが小さく、かつ突起や研磨傷を発生させず、高密度記録が達成可能であり、しかも経済的な速度で研磨できる磁気ディスク基板の研磨用組成物を提供することにある。
【０００５】
【課題を解決するための手段】
本発明者らは、低浮上量型アルミニウム磁気ディスクに要求される高精度の研磨面を達成するための研磨剤について鋭意研究した結果、酸化ケイ素を研磨材とし、これに硝酸アルミニウム、ゲル化防止剤及び過酸化水素を配合してなる研磨用組成物が優れた性能を示すことを見いだし、本発明の完成に至った。
すなわち、本発明は以下の各発明からなる。
（１） 水、酸化ケイ素、ゲル化防止剤、硝酸アルミニウム及び過酸化水素を含む磁気ディスク基板研磨用組成物。
（２） 酸化ケイ素がコロイダルシリカ、ヒュームドシリカ及びホワイトカーボンから選ばれる１種又は２種以上である上記（１）に記載の磁気ディスク基板研磨用組成物。
（３） 酸化ケイ素の二次粒子の平均粒子径が０．０３〜０．５μｍである上記（１）または（２）に記載の磁気ディスク基板研磨用組成物。
（４） 酸化ケイ素の組成物中濃度が３〜３０質量％である上記（１）〜（３）のいずれかに記載の磁気ディスク基板研磨用組成物。
（５） ゲル化防止剤がホスホン酸系化合物、フェナントロリン及びアセチルアセトンアルミニウム塩から選ばれる１種又は２種以上である上記（１）〜（４）のいずれかに記載の磁気ディスク基板研磨用組成物。
（６） ゲル化防止剤がホスホン酸系化合物である上記（５）に記載の磁気ディスク基板研磨用組成物。
（７） ホスホン酸系化合物が１−ヒドロキシエタン−１，１−ジホスホン酸である上記（６）に記載の磁気ディスク基板研磨用組成物。
（８） ゲル化防止剤の組成物中濃度が０．１〜２質量％である上記（１）〜（７）のいずれかに記載の磁気ディスク基板研磨用組成物。
（９） 硝酸アルミニウムの組成物中濃度が１〜２０質量％である上記（１）〜（８）のいずれかに記載の磁気ディスク基板研磨用組成物。
（１０） 過酸化水素の組成物中濃度が０．２〜５質量％である上記（１）〜（９）のいずれか１項に記載の磁気ディスク基板研磨用組成物。
（１１） さらに界面活性剤を含む上記（１）〜（１０）のいずれかに記載の磁気ディスク基板研磨用組成物。
（１２） さらに防腐剤を含む上記（１）〜（１１）のいずれかに記載の磁気ディスク基板研磨用組成物。
（１３） 水で希釈して上記（４）及び（８）〜（１０）のいずれかに記載の磁気ディスク基板研磨用組成物となる濃厚な組成物。
（１４） 上記（１３）に記載の濃厚な組成物として運搬する磁気ディスク基板研磨用組成物の運搬方法。
（１５） 上記（１）〜（１２）のいずれかに記載の磁気ディスク基板研磨用組成物を用いて研磨する磁気ディスク基板の研磨方法。
（１６） 上記（１３）に記載の濃厚な組成物を希釈して研磨に用いる磁気ディスク基板の研磨方法。
（１７） 上記（１５）または（１６）に記載の磁気ディスク基板の研磨方法で研磨する工程を含む磁気ディスク基板の製造方法。
【０００６】
本発明によれば、水、酸化ケイ素、ゲル化防止剤、硝酸アルミニウム及び過酸化水素を含んでなる組成物であって、ゲル化防止剤、硝酸アルミニウム及び過酸化水素の３成分が混在することにより、より高い研磨速度が得られることを特徴とする磁気ディスク基板研磨用組成物が提供される。
本発明の研磨用組成物は、例えば磁気抵抗（ＭＲ）効果を利用した磁気ヘッド用磁気ディスクに代表される高記録密度用の基板（通常、１Ｇｂｉｔ／ｉｎｃｈ2 以上の記録密度を有する）に有利に適用できるが、それ以下の記録密度を有する磁気ディスクに対しても信頼性向上という見地から効果的に応用できる。
【０００７】
【発明の実施の形態】
本発明の研磨用組成物に研磨材として含まれる酸化ケイ素は、特に限定されるものではなく、コロイダルシリカ、ヒュームドシリカ、ホワイトカーボンでも良く、二次粒子の平均粒子径は０．０３〜０．５μｍであることが好ましい。二次粒子の平均粒子径はレーザードップラー周波数解析式粒度分布測定器、マイクロトラックＵＰＡ１５０（Ｈｏｎｅｙｗｅｌｌ社製）により測定した値である。
酸化ケイ素の二次粒子径が大きくなると細目のゲル化、凝集は抑制しやすくなるが、粗い粒子の存在確率も高くなるため、研磨傷発生の原因となる。また、二次粒子径が小さくなると、前述のゲル化、凝集が起きやすくなり、やはり研磨傷発生の原因となる。従って、本発明の研磨用組成物に研磨材として含まれる酸化ケイ素の二次粒子の平均粒子径は０．０３〜０．５μｍであることが好ましく、更には０．０４〜０．２μｍがより好ましい。
【０００８】
研磨用組成物中の酸化ケイ素の濃度が３質量％未満の場合は研磨速度が著しく低い。また、濃度が高くなるにつれて研磨速度は高くなるが、３０質量％を越えると研磨速度の上昇が見られないだけでなく、特にコロイダルシリカではゲル化しやすくなる。経済性を加味すると実用的には３０質量％が上限となる。従って、酸化ケイ素の組成物中濃度としては３〜３０質量％の範囲であることが好ましく、更には５〜１５質量％が好ましい。
【０００９】
本発明の研磨用組成物に用いるゲル化防止剤、硝酸アルミニウム及び過酸化水素はこれら３成分の混在により、大きな研磨促進の効果を出すが、それぞれの添加量はゲル化防止剤が０．１〜２質量％、更に好ましくは０．３〜１質量％、硝酸アルミニウムが１〜２０質量％、更に好ましくは２〜１５質量％、過酸化水素が０．２〜５質量％、更に好ましくは０．５〜３質量％である。
ゲル化防止剤の添加量が０．１質量％未満では研磨促進への効果が低く、なお且つ、ゲル化しやすくなる。また、ゲル化防止剤の添加量が２質量％を越えても研磨促進への効果は高くならない。
【００１０】
硝酸アルミニウムの添加量が１質量％未満では研磨促進への効果が低い。また、硝酸アルミニウムの添加量が２０質量％を越えるとよりゲル化しやすくなる傾向がある。
過酸化水素の添加量が０．２質量％未満では研磨促進への効果が低い。また、過酸化水素の添加量が５質量％を越えても研磨促進への効果は高くならない。
【００１１】
本発明に用いられるゲル化防止剤は、好ましくはホスホン酸系化合物、フェナントロリン及びアセチルアセトンアルミニウム塩から選ばれた１種又は２種以上の混合物である。具体的には、ホスホン酸系化合物としては、１−ヒドロキシエタン−１，１−ジホスホン酸（Ｃ2 Ｈ6 Ｏ7 Ｐ2 ）若しくはアミノトリメチレンホスホン酸（Ｃ2 Ｈ12Ｏ9 Ｐ3 Ｎ）を、フェナントロリンとしては、１，１０−フェナントロリン一水和物（Ｃ12Ｈ8 Ｎ2 ・Ｈ2 Ｏ）を、アセチルアセトンアルミニウム塩としては、アセチルアセトンのアルミニウム錯塩（Ａｌ2 〔ＣＨ（ＣＯＣＨ3 ）3 〕）をそれぞれ例示することが出来る。この中でも特に、研磨促進としては１−ヒドロキシエタン−１，１−ジホスホン酸の効果が一番高い。
【００１２】
上記の各成分濃度は磁気ディスク基板を研磨する際の濃度である。研磨用組成物を製造し、運搬等する場合は上記濃度より濃厚な組成物とし、使用に際して上記の濃度に薄めて使用するのが効率的である。
【００１３】
本発明の研磨用組成物は酸化ケイ素にゲル化防止剤、硝酸アルミニウム及び過酸化水素の３成分を混在させることにより、大きな研磨促進の効果を出すが、そのメカニズムについては定かではないが、ゲル化防止剤の分散効果によるマイルドな機械研磨作用、過酸化水素の酸化効果が硝酸アルミニウムの研磨促進効果を増幅させ化学研磨作用をより効果的にさせるように働いていることが推測される。これら３成分が混在することにより、どの２成分の混在よりも研磨速度が高く、研磨傷及びピットの発生を抑制することが確認されている。
【００１４】
本発明の磁気ディスク基板の研磨用組成物は前記の各成分の他に、界面活性剤、防腐剤等を添加することができる。しかし、その種類及び添加量はゲル化を引き起こさないよう注意が必要である。
本発明の研磨用組成物は、従来の研磨用組成物と同様に、水に酸化ケイ素を懸濁し、これにゲル化防止剤、硝酸アルミニウム及び過酸化水素等を添加することによって調製することができる。
【００１５】
本発明の研磨用組成物を適用する磁気ハードディスク基板は格別限定されるものではないが、アルミニウム（合金を含む）基板、とくに、例えばＮｉＰを無電解メッキしたアルミニウム基板の研磨に本発明の組成物を適用すると、酸化ケイ素によるマイルドな機械的研磨作用とゲル化防止剤、硝酸アルミニウム及び過酸化水素による化学的研磨作用とが相俟って、高品質の研磨面が得られる。
研磨方法は一般にスラリー状研磨材に用いられる研磨パッドを磁気ディスク基板上に摺り合わせ、パッドと基板の間にスラリーを供給しながらパッドまたは基板を回転させる方法である。
本発明の研磨用組成物を用いて研磨した基板からつくられた磁気ディスクは、マイクロピット、マイクロスクラッチ等微細な欠陥について発生頻度が非常に低く、また表面粗さ（Ｒａ）も０．２〜０．３ｎｍ位であり、非常に平滑性に優れている。
【００１６】
【実施例】
以下、本発明の実施例について具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
（実施例１〜１３）
コロイダルシリカ（デュポン（株）製、サイトンＨＴ−５０Ｆ）に水、ゲル化防止剤、硝酸アルミニウム及び過酸化水素を表２に示す割合で添加し、種々の水性研磨用組成物を調製し、以下に示す研磨装置および研磨条件で研磨を行った。その結果を表２に示す。
なお、粒子径はレーザードップラー周波数解析式粒度分布測定器、マイクロトラックＵＰＡ１５０（Ｈｏｎｅｙｗｅｌｌ社製）により測定した。粒度測定値を表１に示す。
【００１７】
（実施例１４、１５）
ホワイトカーボン（日本シリカ工業（株）製、Ｅ−１５０Ｊ）及びヒュームドシリカ（日本アエロジル（株）製、ＡＥＲＯＳＩＬ５０）を媒体攪拌ミルにより粉砕、整粒により粗粒子を除去し、二次粒子の平均粒子径が０．１μｍの酸化ケイ素を調製した。次に、水、ゲル化防止剤、硝酸アルミニウム及び過酸化水素を表２に示す割合で添加し、種々の水性研磨用組成物を調製し、以下に示す研磨装置および研磨条件で研磨を行った。その結果を表２に示す。なお、粒度測定値は表１に示す。
【００１８】
研磨条件
使用した基板：ＮｉＰを無電解メッキした３．５インチサイズのアルミニウムディスク。
使用した研磨装置および研磨条件
研磨試験機‥‥‥‥‥４ウェイ式両面ポリシングマシン
研磨パッド‥‥‥‥‥スエードタイプ（ポリテックスＤＧ、ロデール社製）
下定盤回転速度‥‥‥６０ｒｐｍ
スラリー供給速度‥‥５０ｍｌ／ｍｉｎ
研磨時間‥‥‥‥‥‥５ｍｉｎ
加工圧力‥‥‥‥‥‥５０ｇ／ｃｍ2
【００１９】
研磨特性の評価
研磨レート‥‥アルミニウムディスクの研磨前後の重量減より換算。
表面粗さ‥‥‥タリステップ、タリデータ２０００（ランクテーラーホブソン社製）を使用。
研磨傷および研磨ピットの深さは触針式表面解析装置Ｐ−１２（ＴＥＮＣＯＲ社製）の３次元モードにより形状解析し深さをもとめた。
研磨特性の評価結果を表２に示す。表２中の研磨傷Ａは研磨傷深さが５ｎｍ以下であり、研磨傷Ｂは研磨傷深さが５〜１０ｎｍである。またピットＡはピット深さが５ｎｍ以下であり、ピットＢはピット深さが５〜１０ｎｍである。研磨傷深さが１０ｎｍより大なもの、またピット深さが１０ｎｍより大なものは、実施例、比較例共に発生しなかった。
【００２０】
（比較例１〜２）
コロイダルシリカ（サイトンＨＴ−５０Ｆ、デュポン（株）製）に水、ゲル化防止剤、硝酸アルミニウム及び過酸化水素を表２に示す割合で添加し、水性研磨用組成物を調製し、実施例と同様に研磨した。その結果を表２に示す。
【００２１】
（比較例３）
酸化チタニウム（スーパータイタニアＦ−２、昭和タイタニウム（株）製）を媒体攪拌ミルにより粉砕、整粒により粗粒子を除去し、平均粒子径０．３μｍの酸化チタニウムをまず得た。次に、水、硝酸アルミニウムを表２に示す割合で添加し、水性研磨用組成物を調製し、実施例と同様に研磨した。その結果を表２に示す。なお、粒度測定値は表１に示す。
【００２２】
【表１】
【表２】
【発明の効果】
本発明の研磨用組成物を用いてディスクの研磨を行うと、表面粗さが非常に小さく、しかも高い速度で研磨することが出来る。研磨したディスクを用いた磁気ディスクは低浮上型ハードディスクとして有用であり、高密度記録が可能である。
特に、研磨したディスクを用いた磁気ディスクは、ＭＲヘッド用メディアに代表される高記録密度媒体（１Ｇｂｉｔ／ｉｎｃｈ2 以上の記録密度を有する）として有用度が高い。それ以下の記録密度を有する磁気ディスクに対しても高信頼性媒体と言う観点で有用である。[0001]
The present invention relates to a composition for polishing a magnetic disk substrate, and more particularly to a composition for polishing a magnetic disk substrate from which a highly accurate magnetic disk surface suitable for a magnetic head flying with a low flying height can be obtained.
[0002]
[Prior art]
Magnetic disks (memory hard disks) are widely used as a means for high-speed access in external storage devices of computers and word processors. A typical example of this magnetic disk is a substrate obtained by electrolessly plating NiP on the surface of an Al alloy substrate. After polishing the surface of the substrate, a Cr alloy underlayer, a Co alloy magnetic layer, and a carbon protective layer are sequentially formed. It is formed with a sputter.
If a protrusion having a height higher than the flying height of the magnetic head remains on the surface of the magnetic disk, the magnetic head flying at a high speed while flying at a predetermined height may collide with the protrusion and be damaged. Also, if there are protrusions or polishing scratches on the magnetic disk substrate, when a Cr alloy underlayer film or Co alloy magnetic film is formed, protrusions appear on the surface of those films, and defects based on the polishing scratches occur, resulting in magnetic disk Since the surface does not become a highly accurate smooth surface, it is necessary to polish the substrate precisely in order to increase the accuracy of the disk surface.
[0003]
For this reason, many polishing compositions have been proposed in which the protrusions are eliminated or the height thereof is made as low as possible and polishing scratches hardly occur in polishing of the magnetic disk substrate. In particular, Japanese Patent Laid-Open No. 10-121035 (using a composition formed by adding aluminum nitrate to titania) uses submicron titanium oxide particles as abrasive grains, so that the surface accuracy and polishing rate are higher than conventional ones. Although it is easy to achieve, the level of surface accuracy required recently is difficult to achieve due to the hardness of the abrasive material. JP-A-11-167715 (using a composition obtained by adding aluminum nitrate to colloidal silica) uses silicon oxide fine particles with low hardness in the abrasive grains, but surface accuracy is easily obtained, but in actual production. It was difficult to achieve a usable polishing rate.
[0004]
[Problems to be solved by the invention]
The quality required for an aluminum magnetic disk substrate polishing composition that enables high-density magnetic recording is to achieve a high-precision disk surface that enables low head flying.
SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing composition for a magnetic disk substrate that has a low surface roughness of the magnetic disk, can generate high density recording without generating protrusions or polishing flaws, and can be polished at an economical speed. Is to provide.
[0005]
[Means for Solving the Problems]
As a result of diligent research on abrasives for achieving a high-precision polished surface required for a low flying height type aluminum magnetic disk, the present inventors have used silicon oxide as an abrasive, and this includes aluminum nitrate and anti-gelling. It has been found that a polishing composition comprising an agent and hydrogen peroxide exhibits excellent performance, and the present invention has been completed.
That is, the present invention comprises the following inventions.
(1) A magnetic disk substrate polishing composition comprising water, silicon oxide, an antigelling agent, aluminum nitrate and hydrogen peroxide.
(2) The magnetic disk substrate polishing composition according to (1), wherein the silicon oxide is one or more selected from colloidal silica, fumed silica, and white carbon.
(3) The composition for polishing a magnetic disk substrate according to the above (1) or (2), wherein the secondary particles of silicon oxide have an average particle size of 0.03 to 0.5 μm.
(4) The composition for polishing a magnetic disk substrate according to any one of (1) to (3), wherein the concentration of silicon oxide in the composition is 3 to 30% by mass.
(5) The composition for polishing a magnetic disk substrate according to any one of (1) to (4), wherein the gelation inhibitor is one or more selected from phosphonic acid compounds, phenanthroline and acetylacetone aluminum salt. .
(6) The composition for polishing a magnetic disk substrate according to the above (5), wherein the gelation inhibitor is a phosphonic acid compound.
( 7 ) The composition for polishing a magnetic disk substrate according to the above ( 6 ), wherein the phosphonic acid compound is 1-hydroxyethane-1,1-diphosphonic acid.
(8) The composition for polishing a magnetic disk substrate according to any one of (1) to (7), wherein the concentration of the gelation inhibitor in the composition is 0.1 to 2% by mass.
(9) The composition for polishing a magnetic disk substrate according to any one of (1) to (8), wherein the concentration of aluminum nitrate in the composition is 1 to 20% by mass.
(10) The composition for polishing a magnetic disk substrate according to any one of (1) to (9), wherein the concentration of hydrogen peroxide in the composition is 0.2 to 5% by mass.
(11) The composition for polishing a magnetic disk substrate according to any one of (1) to (10), further comprising a surfactant.
(12) The magnetic disk substrate polishing composition according to any one of (1) to (11), further comprising a preservative.
(13) A concentrated composition that is diluted with water to become the magnetic disk substrate polishing composition according to any one of (4) and (8) to (10).
(14) A method for transporting a magnetic disk substrate polishing composition that is transported as a concentrated composition according to (13).
(15) A method for polishing a magnetic disk substrate, comprising polishing using the magnetic disk substrate polishing composition according to any one of (1) to (12) above.
(16) A method for polishing a magnetic disk substrate used for polishing by diluting the thick composition according to (13).
(17) A method for manufacturing a magnetic disk substrate, comprising a step of polishing by the method for polishing a magnetic disk substrate according to (15) or (16).
[0006]
According to the present invention, a composition comprising water, silicon oxide, an anti-gelling agent, aluminum nitrate and hydrogen peroxide, wherein the three components of the anti-gelling agent, aluminum nitrate and hydrogen peroxide are mixed. Provides a polishing composition for a magnetic disk substrate characterized in that a higher polishing rate can be obtained.
The polishing composition of the present invention is advantageous for high recording density substrates (typically having a recording density of 1 Gbit / inch 2 or more) typified by a magnetic disk for a magnetic head using the magnetoresistive (MR) effect, for example. However, it can be effectively applied to a magnetic disk having a recording density lower than that from the viewpoint of improving reliability.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The silicon oxide contained in the polishing composition of the present invention as an abrasive is not particularly limited, and may be colloidal silica, fumed silica, white carbon, and the average particle size of secondary particles is 0.03 to 0. It is preferably 5 μm. The average particle diameter of the secondary particles is a value measured by a laser Doppler frequency analysis type particle size distribution analyzer, Microtrac UPA150 (manufactured by Honeywell).
When the secondary particle diameter of silicon oxide is increased, fine gelation and aggregation are easily suppressed, but the existence probability of coarse particles is increased, which causes polishing scratches. Further, when the secondary particle size is reduced, the above-mentioned gelation and aggregation are liable to occur, which also causes polishing scratches. Therefore, the average particle diameter of the secondary particles of silicon oxide contained as an abrasive in the polishing composition of the present invention is preferably 0.03 to 0.5 μm, and more preferably 0.04 to 0.2 μm. preferable.
[0008]
When the concentration of silicon oxide in the polishing composition is less than 3% by mass, the polishing rate is extremely low. Further, the polishing rate increases as the concentration increases. However, when the concentration exceeds 30% by mass, not only the polishing rate does not increase, but particularly colloidal silica is easily gelled. In consideration of economy, the upper limit is practically 30% by mass. Therefore, the concentration of silicon oxide in the composition is preferably in the range of 3 to 30% by mass, and more preferably 5 to 15% by mass.
[0009]
The anti-gelling agent, aluminum nitrate and hydrogen peroxide used in the polishing composition of the present invention have a great effect of promoting polishing due to the mixture of these three components. ~ 2 mass%, more preferably 0.3-1 mass%, aluminum nitrate 1-20 mass%, more preferably 2-15 mass%, hydrogen peroxide 0.2-5 mass%, more preferably 0 0.5-3 mass%.
When the addition amount of the anti-gelling agent is less than 0.1% by mass, the effect of promoting the polishing is low, and the gelation easily occurs. Further, even if the addition amount of the anti-gelling agent exceeds 2% by mass, the effect of promoting the polishing does not increase.
[0010]
When the amount of aluminum nitrate added is less than 1% by mass, the effect on the promotion of polishing is low. Moreover, when the addition amount of aluminum nitrate exceeds 20 mass%, it tends to gel more easily.
When the amount of hydrogen peroxide added is less than 0.2% by mass, the effect on the promotion of polishing is low. Further, even if the amount of hydrogen peroxide added exceeds 5% by mass, the effect of promoting polishing does not increase.
[0011]
The antigelling agent used in the present invention is preferably one or a mixture of two or more selected from phosphonic acid compounds, phenanthroline and acetylacetone aluminum salt. Specifically, as the phosphonic acid compound, 1-hydroxyethane-1,1-diphosphonic acid (C 2 H 6 O 7 P 2 ) or aminotrimethylene phosphonic acid (C 2 H 12 O 9 P 3 N) is used. 1,10-phenanthroline monohydrate (C 12 H 8 N 2 .H 2 O) as phenanthroline, and aluminum complex salt of acetylacetone (Al 2 [CH (COCH 3 ) 3 ] as acetylacetone aluminum salt) ) Can be illustrated respectively. Of these, 1-hydroxyethane-1,1-diphosphonic acid is most effective for promoting polishing.
[0012]
Each of the above component concentrations is a concentration at the time of polishing the magnetic disk substrate. When a polishing composition is produced and transported, it is efficient to use a composition thicker than the above concentration and dilute to the above concentration when used.
[0013]
The polishing composition of the present invention produces a large polishing acceleration effect by mixing three components of an antigelling agent, aluminum nitrate and hydrogen peroxide in silicon oxide, but the mechanism is not clear, but the gel It is presumed that the mild mechanical polishing action due to the dispersion effect of the antioxidant and the oxidation effect of hydrogen peroxide work to amplify the polishing promoting effect of aluminum nitrate and make the chemical polishing action more effective. By mixing these three components, it has been confirmed that the polishing rate is higher than that of any two components, and the generation of polishing flaws and pits is suppressed.
[0014]
The polishing composition for a magnetic disk substrate of the present invention may contain a surfactant, a preservative and the like in addition to the above components. However, care must be taken so that the type and amount added do not cause gelation.
The polishing composition of the present invention can be prepared by suspending silicon oxide in water and adding an antigelling agent, aluminum nitrate, hydrogen peroxide, and the like to this, similarly to the conventional polishing composition. it can.
[0015]
The magnetic hard disk substrate to which the polishing composition of the present invention is applied is not particularly limited, but the composition of the present invention is used for polishing an aluminum (including alloy) substrate, particularly, for example, an aluminum substrate electrolessly plated with NiP. Is combined with a mild mechanical polishing action by silicon oxide and a chemical polishing action by an anti-gelling agent, aluminum nitrate and hydrogen peroxide to obtain a high-quality polished surface.
The polishing method is a method in which a polishing pad generally used for a slurry-like abrasive is slid onto a magnetic disk substrate, and the pad or the substrate is rotated while supplying the slurry between the pad and the substrate.
The magnetic disk produced from the substrate polished using the polishing composition of the present invention has a very low frequency of occurrence of fine defects such as micropits and microscratches, and the surface roughness (Ra) is 0.2 to It is about 0.3 nm and is very excellent in smoothness.
[0016]
【Example】
Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.
(Examples 1 to 13)
Water, an antigelling agent, aluminum nitrate and hydrogen peroxide are added to colloidal silica (DuPont Co., Ltd., Cyton HT-50F) in the proportions shown in Table 2, to prepare various aqueous polishing compositions. Polishing was performed using the polishing apparatus and polishing conditions shown in FIG. The results are shown in Table 2.
The particle diameter was measured with a laser Doppler frequency analysis type particle size distribution analyzer, Microtrac UPA150 (manufactured by Honeywell). Table 1 shows the measured particle size.
[0017]
(Examples 14 and 15)
White carbon (manufactured by Nippon Silica Kogyo Co., Ltd., E-150J) and fumed silica (manufactured by Nippon Aerosil Co., Ltd., AEROSIL 50) are pulverized by a medium stirring mill, coarse particles are removed by sizing, and the average of secondary particles Silicon oxide having a particle size of 0.1 μm was prepared. Next, water, an antigelling agent, aluminum nitrate and hydrogen peroxide were added in the proportions shown in Table 2 to prepare various aqueous polishing compositions, and polishing was performed with the following polishing apparatus and polishing conditions. . The results are shown in Table 2. The measured particle size is shown in Table 1.
[0018]
Substrate used for polishing conditions: 3.5 inch size aluminum disc electrolessly plated with NiP.
Polishing equipment and polishing condition polishing tester used 4-way double-side polishing machine polishing pad-Suede type (Polytex DG, manufactured by Rodel)
Lower platen rotation speed 60rpm
Slurry supply speed 50ml / min
Polishing time 5min
Processing pressure 50g / cm 2
[0019]
Evaluation of polishing characteristics Polishing rate: Converted from weight loss before and after polishing of aluminum disk.
Surface roughness: Taristep, Taridata 2000 (Rank Taylor Hobson) is used.
The depth of the polishing scratches and polishing pits was determined by shape analysis using a three-dimensional mode of a stylus type surface analyzer P-12 (manufactured by TENCOR).
Table 2 shows the evaluation results of the polishing characteristics. The polishing flaw A in Table 2 has a polishing flaw depth of 5 nm or less, and the polishing flaw B has a polishing flaw depth of 5 to 10 nm. The pit A has a pit depth of 5 nm or less, and the pit B has a pit depth of 5 to 10 nm. Neither the example nor the comparative example had a polishing flaw depth greater than 10 nm and a pit depth greater than 10 nm.
[0020]
(Comparative Examples 1-2)
Water, an antigelling agent, aluminum nitrate, and hydrogen peroxide were added to colloidal silica (Cytton HT-50F, manufactured by DuPont Co., Ltd.) in the proportions shown in Table 2 to prepare an aqueous polishing composition. Polished in the same manner. The results are shown in Table 2.
[0021]
(Comparative Example 3)
Titanium oxide (Super Titania F-2, manufactured by Showa Titanium Co., Ltd.) was pulverized by a medium stirring mill, and coarse particles were removed by sizing to obtain titanium oxide having an average particle size of 0.3 μm. Next, water and aluminum nitrate were added in the proportions shown in Table 2 to prepare an aqueous polishing composition, which was polished in the same manner as in the examples. The results are shown in Table 2. The measured particle size is shown in Table 1.
[0022]
[Table 1]
[Table 2]
【The invention's effect】
When the disk is polished using the polishing composition of the present invention, the surface roughness is very small and the polishing can be performed at a high speed. A magnetic disk using a polished disk is useful as a low flying type hard disk, and high density recording is possible.
In particular, a magnetic disk using a polished disk is highly useful as a high recording density medium (having a recording density of 1 Gbit / inch 2 or more) typified by an MR head medium. Even a magnetic disk having a recording density lower than that is useful from the viewpoint of a highly reliable medium.
Claims (12)
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000013858A JP3877924B2 (en) | 2000-01-24 | 2000-01-24 | Magnetic disk substrate polishing composition |
| MYPI20010276 MY118633A (en) | 2000-01-24 | 2001-01-22 | Abrasive composition for polishing magnetic recording disk substrates |
| CN 01104631 CN1243070C (en) | 2000-01-24 | 2001-01-23 | Abrasive composition for polishing magnetic recording disk matrix |
| US09/767,024 US6478835B2 (en) | 2000-01-24 | 2001-01-23 | Abrasive composition for polishing magnetic recording disk substrates |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000013858A JP3877924B2 (en) | 2000-01-24 | 2000-01-24 | Magnetic disk substrate polishing composition |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JP2001207161A JP2001207161A (en) | 2001-07-31 |
| JP2001207161A5 JP2001207161A5 (en) | 2005-08-04 |
| JP3877924B2 true JP3877924B2 (en) | 2007-02-07 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000013858A Expired - Lifetime JP3877924B2 (en) | 2000-01-24 | 2000-01-24 | Magnetic disk substrate polishing composition |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3877924B2 (en) |
| CN (1) | CN1243070C (en) |
| MY (1) | MY118633A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4231632B2 (en) * | 2001-04-27 | 2009-03-04 | 花王株式会社 | Polishing liquid composition |
| MY133305A (en) * | 2001-08-21 | 2007-11-30 | Kao Corp | Polishing composition |
| JP4462599B2 (en) * | 2001-08-21 | 2010-05-12 | 花王株式会社 | Polishing liquid composition |
| JP3875156B2 (en) * | 2002-08-07 | 2007-01-31 | 花王株式会社 | Roll-off reducing agent |
| JP4202172B2 (en) * | 2003-03-31 | 2008-12-24 | 株式会社フジミインコーポレーテッド | Polishing composition |
| JP4891304B2 (en) * | 2008-10-23 | 2012-03-07 | 花王株式会社 | Manufacturing method of memory hard disk substrate |
| MY186419A (en) * | 2014-03-28 | 2021-07-22 | Yamaguchi Seiken Kogyo Co Ltd | Polishing composition and method for polishing magnetic disk substrate |
| WO2015146941A1 (en) * | 2014-03-28 | 2015-10-01 | 山口精研工業株式会社 | Polishing agent composition and method for polishing magnetic disk substrate |
| JP6480139B2 (en) * | 2014-09-30 | 2019-03-06 | 株式会社フジミインコーポレーテッド | Polishing composition |
| JP6775511B2 (en) * | 2015-09-25 | 2020-10-28 | 山口精研工業株式会社 | Abrasive composition and method for polishing magnetic disk substrates |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3653133B2 (en) * | 1996-01-30 | 2005-05-25 | 昭和電工株式会社 | Polishing composition, magnetic disk substrate polishing method, and manufacturing method |
| JP3825827B2 (en) * | 1996-01-30 | 2006-09-27 | 昭和電工株式会社 | Polishing composition, magnetic disk substrate polishing method, and manufacturing method |
| JPH10121034A (en) * | 1996-03-18 | 1998-05-12 | Showa Denko Kk | Composition for polishing magnetic disk substrate |
| JPH10121035A (en) * | 1996-08-30 | 1998-05-12 | Showa Denko Kk | Composition for polishing magnetic disk substrate |
| JP3457144B2 (en) * | 1997-05-21 | 2003-10-14 | 株式会社フジミインコーポレーテッド | Polishing composition |
| US6149696A (en) * | 1997-11-06 | 2000-11-21 | Komag, Inc. | Colloidal silica slurry for NiP plated disk polishing |
-
2000
- 2000-01-24 JP JP2000013858A patent/JP3877924B2/en not_active Expired - Lifetime
-
2001
- 2001-01-22 MY MYPI20010276 patent/MY118633A/en unknown
- 2001-01-23 CN CN 01104631 patent/CN1243070C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001207161A (en) | 2001-07-31 |
| CN1309160A (en) | 2001-08-22 |
| CN1243070C (en) | 2006-02-22 |
| MY118633A (en) | 2004-12-31 |
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