JP7392909B2 - Glass substrate for magnetic recording media and magnetic recording device using the same - Google Patents
Glass substrate for magnetic recording media and magnetic recording device using the same Download PDFInfo
- Publication number
- JP7392909B2 JP7392909B2 JP2019212416A JP2019212416A JP7392909B2 JP 7392909 B2 JP7392909 B2 JP 7392909B2 JP 2019212416 A JP2019212416 A JP 2019212416A JP 2019212416 A JP2019212416 A JP 2019212416A JP 7392909 B2 JP7392909 B2 JP 7392909B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic recording
- glass substrate
- glass
- recording medium
- magnetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000011521 glass Substances 0.000 title claims description 77
- 239000000758 substrate Substances 0.000 title claims description 56
- 238000000137 annealing Methods 0.000 claims description 13
- 238000002834 transmittance Methods 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 claims description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 7
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 230000003746 surface roughness Effects 0.000 claims description 7
- 238000000034 method Methods 0.000 description 16
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 16
- 229910052697 platinum Inorganic materials 0.000 description 8
- 238000004031 devitrification Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 239000006066 glass batch Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000006060 molten glass Substances 0.000 description 4
- 238000007500 overflow downdraw method Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 229910018921 CoO 3 Inorganic materials 0.000 description 3
- 229910018068 Li 2 O Inorganic materials 0.000 description 3
- 229910010413 TiO 2 Inorganic materials 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 229910006404 SnO 2 Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 239000006103 coloring component Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000009774 resonance method Methods 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000007088 Archimedes method Methods 0.000 description 1
- 229910015902 Bi 2 O 3 Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 229910005335 FePt Inorganic materials 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 238000006124 Pilkington process Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000006249 magnetic particle Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
Landscapes
- Glass Compositions (AREA)
- Magnetic Record Carriers (AREA)
Description
本発明は、磁気記録媒体用ガラス基板及びそれを用いた磁気記録装置に関する。 The present invention relates to a glass substrate for magnetic recording media and a magnetic recording device using the same.
磁気記録装置は、磁気記録媒体用基板上に磁性層を成膜した磁気記録媒体を備えており、該磁性層を用いて情報を記録することができる。従来まで、磁気記録装置に用いられる磁気記録媒体用基板としてアルミニウム合金基板が使用されてきた。現在では、高記録密度化の要求に伴い、磁気媒体用基板の薄肉化が検討されている。しかし、アルミニウム合金基板を薄くすると剛性がなくなってしまうため、剛性、平坦性、平滑性等に優れるガラス基板に注目が集まっている。 A magnetic recording device includes a magnetic recording medium in which a magnetic layer is formed on a magnetic recording medium substrate, and information can be recorded using the magnetic layer. Until now, aluminum alloy substrates have been used as substrates for magnetic recording media used in magnetic recording devices. Currently, with the demand for higher recording densities, thinner substrates for magnetic media are being considered. However, if aluminum alloy substrates are made thinner, they lose their rigidity, so glass substrates, which have excellent rigidity, flatness, smoothness, etc., are attracting attention.
近年では、更なる高記録密度化のニーズに応えるため、エネルギーアシスト磁気記録方式を用いた磁気記録媒体、つまりエネルギーアシスト磁気記録媒体が検討されている。エネルギーアシスト磁気記録媒体についても、ガラス基板が使用されると共に、ガラス基板の表面上に磁性層等が成膜される。エネルギーアシスト磁気記録媒体では、磁性層の磁性材料として大きな磁気異方性係数Ｋｕ（以下、「高Ｋｕ」と称する）を有する規則合金が用いられる。 In recent years, in order to meet the needs for even higher recording densities, magnetic recording media using an energy-assisted magnetic recording method, that is, energy-assisted magnetic recording media, have been studied. A glass substrate is also used for energy-assisted magnetic recording media, and a magnetic layer and the like are formed on the surface of the glass substrate. In an energy-assisted magnetic recording medium, an ordered alloy having a large magnetic anisotropy coefficient Ku (hereinafter referred to as "high Ku") is used as the magnetic material of the magnetic layer.
磁性層の規則化の程度（規則度）を高めて高Ｋｕ化を図るため、磁性層の成膜時、或いは成膜前後に、ガラス基板を含む基材を８００℃程度の高温で熱処理することがある。この熱処理温度は高記録密度になればなる程、高温が必要になるため、従来の磁気記録媒体用ガラス基板よりも更に高い耐熱性が求められる。また、磁性層の成膜後に、ガラス基板を含む基材に対して、レーザー照射を実行することもある。このような熱処理やレーザー照射は、ＦｅＰｔ系合金等を含む磁性層のアニール温度や保磁力を高めるという目的もある。 In order to increase the degree of ordering (regularity) of the magnetic layer and achieve a high Ku, the base material including the glass substrate is heat-treated at a high temperature of about 800°C during or before and after film formation of the magnetic layer. There is. The higher the recording density, the higher the temperature required for this heat treatment, so higher heat resistance is required than in conventional glass substrates for magnetic recording media. Furthermore, after forming the magnetic layer, laser irradiation may be performed on the base material including the glass substrate. Such heat treatment and laser irradiation also have the purpose of increasing the annealing temperature and coercive force of the magnetic layer containing FePt-based alloy or the like.
ところで、磁気記録媒体用ガラス基板には、高速回転時に大きな変形を起こさないために、高い剛性（ヤング率）を有することが求められる。詳述すると、ディスク状の磁気記録媒体では、媒体を中心軸の周りに高速回転させつつ、磁気ヘッドを半径方向に移動させながら、回転方向に沿って情報の書き込み、読み出しを行う。近年、この書き込み速度や読み出し速度を上げるための回転数は５４００ｒｐｍから７２００ｒｐｍ、更には１００００ｒｐｍと高速化の方向に進んでいるが、ディスク状の磁気記録媒体では、予め中心軸からの距離に応じて情報を記録するポジションが割り当てられる。このため、ガラス基板が回転中に変形を起こすと、磁気ヘッドの位置ズレが起こり、正確な読み取りが困難になる。 Incidentally, glass substrates for magnetic recording media are required to have high rigidity (Young's modulus) in order to avoid large deformation during high-speed rotation. Specifically, in a disk-shaped magnetic recording medium, information is written and read along the rotational direction while the medium is rotated at high speed around the central axis and the magnetic head is moved in the radial direction. In recent years, the number of revolutions to increase the writing speed and reading speed has been increasing from 5,400 rpm to 7,200 rpm, and even 10,000 rpm. You will be assigned a position to record information. Therefore, if the glass substrate is deformed during rotation, the position of the magnetic head will shift, making accurate reading difficult.
また、近年、磁気ヘッドにＤＦＨ（Ｄｙｎａｍｉｃ Ｆｌｙｉｎｇ Ｈｅｉｇｈｔ）機構を搭載させることで、磁気ヘッドの記録再生素子部と磁気記録媒体表面との間隙の大幅な狭小化（低浮上量化）を達成して、更なる高記録密度化を図ることが行われている。ＤＦＨ機構とは、磁気ヘッドの記録再生素子部の近傍に極小のヒーター等の加熱部を設けて、素子部周辺のみを媒体表面方向に向けて熱膨張させる機構である。このような機構を備えることにより、磁気ヘッドと媒体の磁性層との距離が近づくため、より小さい磁性粒子の信号を拾うことができるようになり、高記録密度化を達成することが可能となる。その一方で、磁気ヘッドの記録再生素子部と磁気記録媒体の表面との間隙が、例えば２ｎｍ以下と極めて小さくなるため、僅かな衝撃によっても磁気ヘッドが磁気記録媒体の表面に衝突する虞がある。この傾向は、高速回転になる程、顕著となる。よって、高速回転時には、この衝突の原因になるガラス基板の撓みやバタツキ（フラッタリング）の発生を防ぐことが重要になる。 In addition, in recent years, by installing a DFH (Dynamic Flying Height) mechanism in magnetic heads, the gap between the recording/reproducing element part of the magnetic head and the surface of the magnetic recording medium has been significantly narrowed (lower flying height). Efforts are being made to further increase the recording density. The DFH mechanism is a mechanism in which a heating section such as a very small heater is provided near the recording/reproducing element section of a magnetic head, and only the periphery of the element section is thermally expanded toward the surface of the medium. Equipped with such a mechanism, the distance between the magnetic head and the magnetic layer of the medium becomes closer, making it possible to pick up signals from smaller magnetic particles, making it possible to achieve higher recording density. . On the other hand, because the gap between the read/write element of the magnetic head and the surface of the magnetic recording medium is extremely small, for example, 2 nm or less, there is a risk that the magnetic head will collide with the surface of the magnetic recording medium even with the slightest impact. . This tendency becomes more pronounced as the rotation speed increases. Therefore, during high-speed rotation, it is important to prevent the glass substrate from bending or fluttering, which could cause this collision.
更に、近年のデータセンターやサーバーの世界的な利用増に付随して、これらの磁気ディスク基板の低コスト化が求められている。ガラス基板の低コスト化には、一般的に、低温溶融が有効である。更に、オーバーフローダウンドロ―法、フロート法を採択して、大型のガラス基板を製品の厚みに近い板厚で成形することも有効である。 Furthermore, with the recent increase in the worldwide use of data centers and servers, there is a demand for lower costs for these magnetic disk substrates. Low-temperature melting is generally effective for reducing the cost of glass substrates. Furthermore, it is also effective to adopt the overflow down-draw method or the float method to form a large glass substrate to a thickness close to that of the product.
そこで、本発明は上記事情に鑑み成されたものであり、その目的は、高速回転時に撓みやバタツキ（フラッタリング）が発生し難く、大幅な高記録密度を実現するために十分な耐熱性を備え、しかも低コスト化に資する磁気記録媒体用ガラス基板を創案することである。 Therefore, the present invention has been made in view of the above circumstances, and its purpose is to provide sufficient heat resistance to prevent deflection or fluttering (fluttering) during high-speed rotation and to realize significantly high recording density. An object of the present invention is to create a glass substrate for a magnetic recording medium that is equipped with the above-mentioned features and contributes to cost reduction.
本発明者は、種々の実験を繰り返した結果、ガラス特性を厳密に規制することにより、上記技術的課題を解決し得ることを見出し、本発明として、提案するものである。すなわち、本発明の磁気記録媒体用ガラス基板は、徐冷点が７８０℃以上であり、高温粘度１０２．５ｄＰａ・ｓにおける温度が１６４０℃以下であり、且つヤング率が８０ＧＰａ以上であることを特徴とする。ここで、「徐冷点」は、周知のファイバーエロンゲーション法で測定可能であり、例えばＡＳＴＭ Ｃ３３６の方法に基づいて測定することができる。「ヤング率」は、周知の共振法で測定可能である。「高温粘度１０２．５ｄＰａ・ｓにおける温度」は、周知の白金球引き上げ法で測定可能である。 As a result of repeated various experiments, the inventors of the present invention have found that the above technical problems can be solved by strictly regulating the glass properties, and the present inventors propose this as the present invention. That is, the glass substrate for a magnetic recording medium of the present invention has an annealing point of 780° C. or higher, a temperature of 1640° C. or lower at a high temperature viscosity of 10 2.5 dPa·s, and a Young's modulus of 80 GPa or higher. It is characterized by Here, the "annealing point" can be measured by the well-known fiber elongation method, for example, based on the ASTM C336 method. "Young's modulus" can be measured by the well-known resonance method. "Temperature at high temperature viscosity of 10 2.5 dPa·s" can be measured by the well-known platinum ball pulling method.
本発明の磁気記録媒体用ガラス基板では、徐冷点が７８０℃以上に規制されている。このようにすれば、熱アシスト等の高温での熱処理やレーザー照射を実行しても、ガラス基板の変形が生じ難くなる。結果として、高Ｋｕ化を図る際に、より高い熱処理温度を採用し得るため、高記録密度の磁気記録装置を作製し易くなる。 In the glass substrate for magnetic recording media of the present invention, the annealing point is regulated to 780° C. or higher. In this way, even if heat treatment at a high temperature such as thermal assist or laser irradiation is performed, deformation of the glass substrate becomes less likely to occur. As a result, a higher heat treatment temperature can be used when increasing Ku, making it easier to manufacture a magnetic recording device with high recording density.
また、本発明の磁気記録媒体用ガラス基板では、高温粘度１０２．５ｄＰａ・ｓにおける温度が１６４０℃以下に規制されている。このようにすれば、低温溶融が可能になるため、ガラス基板の低コスト化に寄与することができる。また成形性も高めることができる。 Further, in the glass substrate for a magnetic recording medium of the present invention, the temperature at a high temperature viscosity of 10 2.5 dPa·s is regulated to 1640° C. or lower. In this way, low-temperature melting becomes possible, which can contribute to lowering the cost of glass substrates. Moreover, moldability can also be improved.
更に、本発明の磁気記録媒体用ガラス基板では、ヤング率が８０ＧＰａ以上に規制されている。このようにすれば、高速回転時に、ガラス基板の撓みやバタツキ（フラッタリング）が発生し難くなるため、情報記録媒体と磁気ヘッドの衝突を防止することができる。 Furthermore, in the glass substrate for a magnetic recording medium of the present invention, the Young's modulus is regulated to 80 GPa or more. This makes it difficult for the glass substrate to bend or flutter during high-speed rotation, thereby making it possible to prevent collisions between the information recording medium and the magnetic head.
本発明の磁気記録媒体用ガラス基板は、ガラス組成として、質量％で、ＳｉＯ２ ５５～７０％、Ａｌ２Ｏ３ １７～２５％、Ｂ２Ｏ３ ０～２％、ＭｇＯ ０～６％、ＣａＯ ０～７％、ＳｒＯ ０．１～７％、ＢａＯ ０．１～１５％を含有することが好ましい。 The glass substrate for a magnetic recording medium of the present invention has a glass composition, in mass %, of SiO 2 55-70%, Al 2 O 3 17-25%, B 2 O 3 0-2%, MgO 0-6%, It is preferable to contain 0 to 7% of CaO, 0.1 to 7% of SrO, and 0.1 to 15% of BaO.
また、本発明の磁気記録媒体用ガラス基板は、表面の平均表面粗さＲａが１．０ｎｍ以下であることが好ましい。このようにすれば、高記録密度化のためにビットサイズが微細化されても、磁気特性の改善が可能になる。ここで、「表面の平均表面粗さＲａ」は、端面を除く主表面（両表面）の平均表面粗さＲａを指し、例えば、原子間力顕微鏡（ＡＦＭ）で測定することができる。 Further, it is preferable that the glass substrate for a magnetic recording medium of the present invention has an average surface roughness Ra of 1.0 nm or less. In this way, even if the bit size is miniaturized to increase the recording density, it is possible to improve the magnetic properties. Here, the "average surface roughness Ra of the surface" refers to the average surface roughness Ra of the main surface (both surfaces) excluding the end surfaces, and can be measured using, for example, an atomic force microscope (AFM).
また、本発明の磁気記録媒体用ガラス基板は、光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率が７０％以上であることが好ましい。 Further, it is preferable that the glass substrate for a magnetic recording medium of the present invention has an optical path length of 1 mm and an average linear transmittance of 70% or more in a wavelength range of 350 to 1500 nm.
また、本発明の磁気記録媒体用ガラス基板は、ディスク形状、つまり円盤形状であり、且つ中心部に円形の開口部が形成されている形状（図1参照）であることが好ましい。 Further, the glass substrate for a magnetic recording medium of the present invention preferably has a disk shape, that is, a disk shape, and has a circular opening formed in the center (see FIG. 1).
また、本発明の磁気記録装置は、上記の磁気記録媒体用ガラス基板を備えることが好ましい。 Further, the magnetic recording device of the present invention preferably includes the above-mentioned glass substrate for a magnetic recording medium.
本発明の磁気記録媒体用ガラス基板において、徐冷点は、好ましくは７８０℃以上、７８５℃以上、７９０℃以上、７９５℃以上、８００℃以上、特に好ましくは８０５～９００℃である。徐冷点が低過ぎると、高温での熱処理やレーザー照射を実行し難くなり、高記録密度の磁気記録媒体を作製し難くなる。 In the glass substrate for magnetic recording media of the present invention, the annealing point is preferably 780°C or higher, 785°C or higher, 790°C or higher, 795°C or higher, 800°C or higher, particularly preferably 805 to 900°C. If the annealing point is too low, it will be difficult to perform heat treatment at high temperatures or laser irradiation, and it will be difficult to produce a magnetic recording medium with high recording density.
本発明の磁気記録媒体用ガラス基板において、高温粘度１０２．５ｄＰａ・ｓにおける温度は、好ましくは１６４０℃以下、１６３５℃以下、１６３０℃以下、特に１４５０～１６２５℃である。高温粘度１０２．５ｄＰａ・ｓにおける温度が高過ぎると、溶融性や成形性が低下して、ガラス基板の製造コストが高騰する。 In the glass substrate for magnetic recording media of the present invention, the temperature at a high temperature viscosity of 10 2.5 dPa·s is preferably 1640°C or lower, 1635°C or lower, 1630°C or lower, particularly 1450 to 1625°C. If the temperature at a high-temperature viscosity of 10 2.5 dPa·s is too high, the meltability and moldability will decrease and the manufacturing cost of the glass substrate will increase.
本発明の磁気記録媒体用ガラス基板において、ヤング率は、好ましくは８０ＧＰａ以上、８１ＧＰａ以上、８２ＧＰａ以上、特に好ましくは８３～１００ＧＰａである。ヤング率が低過ぎると、高速回転時に、ガラス基板の撓みやバタツキ（フラッタリング）が発生し易くなるため、情報記録媒体と磁気ヘッドが衝突し易くなる。 In the glass substrate for magnetic recording media of the present invention, Young's modulus is preferably 80 GPa or more, 81 GPa or more, 82 GPa or more, particularly preferably 83 to 100 GPa. If the Young's modulus is too low, the glass substrate tends to bend or flutter during high-speed rotation, making it easier for the information recording medium to collide with the magnetic head.
本発明の磁気記録媒体用ガラス基板は、ガラス組成として、質量％で、ＳｉＯ２ ５５～７０％、Ａｌ２Ｏ３ １７～２５％、Ｂ２Ｏ３ ０～２％、ＭｇＯ ０～６％、ＣａＯ ０～７％、ＳｒＯ ０．１～７％、ＢａＯ ０．１～１５％を含有することが好ましい。上記のように各成分の含有量を限定した理由を以下に示す。なお、各成分の含有量の説明において、％表示は、特に断りがある場合を除き、質量％を表す。 The glass substrate for a magnetic recording medium of the present invention has a glass composition, in mass %, of SiO 2 55-70%, Al 2 O 3 17-25%, B 2 O 3 0-2%, MgO 0-6%, It is preferable to contain 0 to 7% of CaO, 0.1 to 7% of SrO, and 0.1 to 15% of BaO. The reason why the content of each component was limited as described above is shown below. In addition, in the description of the content of each component, % represents mass % unless otherwise specified.
ＳｉＯ２は、ガラスのネットワークを形成する成分である。ＳｉＯ２の含有量は、好ましくは５５～７０％、５６～６７％、５７～６５％、特に５８～６３％である。ＳｉＯ２の含有量が少な過ぎると、ガラス化し難くなり、また耐熱性が低下し易くなる。一方、ＳｉＯ２の含有量が多過ぎると、溶融性、成形性、ヤング率が低下し易くなる。 SiO 2 is a component that forms the glass network. The content of SiO 2 is preferably 55-70%, 56-67%, 57-65%, especially 58-63%. If the content of SiO 2 is too low, it becomes difficult to vitrify and the heat resistance tends to decrease. On the other hand, if the content of SiO 2 is too large, meltability, moldability, and Young's modulus tend to decrease.
Ａｌ２Ｏ３は、ヤング率や徐冷点を高める成分である。Ａｌ２Ｏ３の含有量は、好ましくは１７～２５％、１８～２３％、１８．５～２１％、特に１９～２０％である。Ａｌ２Ｏ３の含有量が少な過ぎると、ヤング率や耐熱性が低下し易くなる。一方、Ａｌ２Ｏ３の含有量が多過ぎると、溶融性、成形性、耐失透性が低下し易くなる。 Al 2 O 3 is a component that increases Young's modulus and annealing point. The content of Al 2 O 3 is preferably 17-25%, 18-23%, 18.5-21%, especially 19-20%. If the content of Al 2 O 3 is too low, Young's modulus and heat resistance tend to decrease. On the other hand, if the content of Al 2 O 3 is too large, meltability, moldability, and devitrification resistance tend to decrease.
Ｂ２Ｏ３は、ガラスのネットワークを形成する成分であるが、ヤング率や耐熱性を低下させる成分である。よって、Ｂ２Ｏ３の含有量は、好ましくは０～２％、０．１～１．８％、０．３～１．５％、特に０．４～１％である。 B 2 O 3 is a component that forms a glass network, but it is a component that lowers Young's modulus and heat resistance. Therefore, the content of B 2 O 3 is preferably 0-2%, 0.1-1.8%, 0.3-1.5%, especially 0.4-1%.
ＭｇＯは、ヤング率を大幅に高める成分であり、また高温粘度を低下させて、溶融性や成形性を高める成分である。ＭｇＯの含有量は、好ましくは０～６％、１～６％、１．５～５％、２～５％、２～４．５％、特に２．５～４％である。ＭｇＯの含有量が少な過ぎると、上記効果を享受し難くなる。一方、ＭｇＯの含有量が多過ぎると、耐熱性、耐失透性が低下し易くなる。 MgO is a component that significantly increases Young's modulus, and also lowers high temperature viscosity and improves meltability and moldability. The MgO content is preferably 0-6%, 1-6%, 1.5-5%, 2-5%, 2-4.5%, especially 2.5-4%. If the MgO content is too low, it will be difficult to enjoy the above effects. On the other hand, if the MgO content is too large, heat resistance and devitrification resistance tend to decrease.
ＣａＯは、高温粘度を低下させて、溶融性及び成形性を高める成分である。ＣａＯの含有量は、好ましくは０～７％、１～６％、２～５％、特に２．５～４．５％である。ＣａＯの含有量が少な過ぎると、上記効果を享受し難くなる。一方、ＣａＯの含有量が多過ぎると、耐失透性が低下し易くなる。 CaO is a component that lowers high temperature viscosity and improves meltability and moldability. The CaO content is preferably 0-7%, 1-6%, 2-5%, especially 2.5-4.5%. If the CaO content is too low, it will be difficult to enjoy the above effects. On the other hand, if the content of CaO is too large, the devitrification resistance tends to decrease.
ＳｒＯは、他の成分とのバランスを取り、耐失透性を高める効果があり、特に無アルカリガラス系ではガラスの安定化に必須の成分である。一方、ＳｒＯの含有量が多過ぎると、ＣａＯ系の結晶析出が促進されて、耐失透性が低下することを加えて、ヤング率も低下してしまう。よって、ＳｒＯの含有量は、好ましくは０．１～７％、０．１～６％、０．５～５％、１～４．５％、特に１～４％である。 SrO has the effect of maintaining balance with other components and increasing resistance to devitrification, and is an essential component for stabilizing glass, especially in alkali-free glass systems. On the other hand, if the content of SrO is too large, precipitation of CaO-based crystals will be promoted, resulting in a decrease in devitrification resistance and a decrease in Young's modulus. Therefore, the content of SrO is preferably 0.1 to 7%, 0.1 to 6%, 0.5 to 5%, 1 to 4.5%, particularly 1 to 4%.
ＢａＯは、ＣａＯ系の結晶析出を低減する効果があり、特に無アルカリガラス系ではガラスの安定化に必須の成分である。一方、ＢａＯの含有量を多過ぎると、ヤング率が低下し易くなる。よって、ＢａＯの含有量は、好ましくは０．１～１５％、３～１３％、４～１２％、５～１２％、特に６～１１％である。 BaO has the effect of reducing the precipitation of CaO-based crystals, and is an essential component for stabilizing the glass, especially in alkali-free glass systems. On the other hand, if the BaO content is too high, the Young's modulus tends to decrease. Therefore, the BaO content is preferably 0.1 to 15%, 3 to 13%, 4 to 12%, 5 to 12%, particularly 6 to 11%.
上記成分以外にも、例えば以下の成分を添加してもよい。 In addition to the above components, for example, the following components may be added.
Ｌｉ２Ｏ、Ｎａ２Ｏ及びＫ２Ｏは、高温粘度を低下させて、溶融性及び成形性を高める成分であるが、耐水性や耐候性を低下させる成分である。Ｌｉ２Ｏ、Ｎａ２Ｏ及びＫ２Ｏの合量は、好ましくは０～１５％、０～１０％、０～５％、０～１％、特に０～０．１％未満である。Ｌｉ２Ｏ、Ｎａ２Ｏ及びＫ２Ｏのそれぞれの含有量は、好ましくは０～１０％、０～５％、０～１％未満、特に０～０．１％未満である。 Li 2 O, Na 2 O, and K 2 O are components that reduce high-temperature viscosity and improve meltability and moldability, but they are components that reduce water resistance and weather resistance. The total amount of Li 2 O, Na 2 O and K 2 O is preferably from 0 to 15%, from 0 to 10%, from 0 to 5%, from 0 to 1%, especially from 0 to less than 0.1%. The respective contents of Li 2 O, Na 2 O and K 2 O are preferably from 0 to 10%, from 0 to 5%, from 0 to less than 1%, especially from 0 to less than 0.1%.
ＺｎＯは、高温粘性を下げて、溶融性を顕著に高める成分である。ＺｎＯの含有量は、好ましくは０～７％、０．１～５％、特に０．５～３％である。ＺｎＯの含有量が少な過ぎると、上記効果を享受し難くなる。なお、ＺｎＯの含有量が多過ぎると、ガラスが失透し易くなる。 ZnO is a component that lowers high temperature viscosity and significantly increases meltability. The content of ZnO is preferably 0-7%, 0.1-5%, especially 0.5-3%. If the ZnO content is too low, it will be difficult to enjoy the above effects. Note that if the ZnO content is too large, the glass tends to devitrify.
ＴｉＯ２は、耐水性や耐候性を高める成分であるが、ガラスを着色させる成分である。しかし、ＴｉＯ２の含有量が多過ぎると、光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率が低下し易くなる。よって、ＴｉＯ２の含有量は、好ましくは０～０．５％、特に０～０．１％未満である。 TiO 2 is a component that improves water resistance and weather resistance, but it is also a component that colors glass. However, if the content of TiO 2 is too large, the average linear transmittance in the optical path length of 1 mm and the wavelength range of 350 to 1500 nm tends to decrease. The content of TiO 2 is therefore preferably between 0 and 0.5%, especially between 0 and less than 0.1%.
清澄剤として、ＳｎＯ２、Ｃｌ、ＳＯ３、ＣｅＯ２の群（好ましくはＳｎＯ２、ＳＯ３の群）から選択された一種又は二種以上を０．０５～０．５％添加してもよい。 As a clarifier, 0.05 to 0.5% of one or more selected from the group of SnO 2 , Cl, SO 3 and CeO 2 (preferably the group of SnO 2 and SO 3 ) may be added. .
Ｆｅ２Ｏ３は、ガラス原料に不純物として不可避的に混入する成分であり、着色成分である。よって、Ｆｅ２Ｏ３の含有量は、好ましくは０．５％以下、０．００１～０．１％、０．００５～０．０７％、０．００８～０．０２５％、特に０．０１～０．０３％である。Ｆｅ２Ｏ３の含有量が多過ぎると、光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率が低下し易くなる。 Fe 2 O 3 is a component that is inevitably mixed into glass raw materials as an impurity, and is a coloring component. Therefore, the content of Fe 2 O 3 is preferably 0.5% or less, 0.001 to 0.1%, 0.005 to 0.07%, 0.008 to 0.025%, especially 0.01%. ~0.03%. If the content of Fe 2 O 3 is too large, the average linear transmittance in the optical path length of 1 mm and the wavelength range of 350 to 1500 nm tends to decrease.
Ｖ２Ｏ５、Ｃｒ２Ｏ３、ＣｏＯ３及びＮｉＯは、着色成分である。よって、Ｖ２Ｏ５、Ｃｒ２Ｏ３、ＣｏＯ３及びＮｉＯのそれぞれの含有量は、好ましくは０．１％以下、特に０．０１％未満である。Ｖ２Ｏ５、Ｃｒ２Ｏ３、ＣｏＯ３及びＮｉＯのそれぞれの含有量が多過ぎると、光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率が低下し易くなる。 V 2 O 5 , Cr 2 O 3 , CoO 3 and NiO are coloring components. Therefore, the content of each of V 2 O 5 , Cr 2 O 3 , CoO 3 and NiO is preferably 0.1% or less, particularly less than 0.01%. If the content of each of V 2 O 5 , Cr 2 O 3 , CoO 3 and NiO is too large, the average in-line transmittance in the optical path length of 1 mm and the wavelength range of 350 to 1500 nm tends to decrease.
環境的配慮から、ガラス組成として、実質的にＡｓ２Ｏ３、Ｓｂ２Ｏ３、ＰｂＯ、Ｂｉ２Ｏ３及びＦを含有しないことが好ましい。ここで、「実質的に～を含有しない」とは、ガラス成分として積極的に明示の成分を添加しないものの、不純物として混入する場合を許容する趣旨であり、具体的には、明示の成分の含有量が０．０５％未満であることを指す。 From environmental considerations, it is preferable that the glass composition does not substantially contain As 2 O 3 , Sb 2 O 3 , PbO, Bi 2 O 3 and F. Here, "substantially does not contain..." means that although the specified ingredients are not actively added as glass components, it is allowed to be mixed in as impurities. It means that the content is less than 0.05%.
本発明の磁気記録媒体用ガラス基板は、以下の特性を有することが好ましい。 The glass substrate for magnetic recording media of the present invention preferably has the following characteristics.
磁気記録媒体用ガラス基板には、磁気記録媒体の記録再生の信頼性を高めるために、適正な熱膨張係数を有することが求められる。詳述すると、磁気記録媒体を組み込んだＨＤＤ（ハードディスクドライブ）は、中央部分をスピンドルモーターのスピンドルで押圧して、磁気記録媒体自身を回転させる構造を備えている。このため、ガラス基板とスピンドル材料の熱膨張係数差が大き過ぎると、周囲の温度変化に対して、両者の熱膨張・熱収縮が相違するため、磁気記録媒体が変形するという現象が生じる。このような現象が生じると、書き込んだ情報を磁気ヘッドで読み出せなくなってしまい、記録再生の信頼性を損なう虞がある。よって、磁気記録媒体用ガラス基板には、スピンドル材料（例えばステンレス等）の熱膨張係数に整合する熱膨張係数を有していることが望ましい。このような観点から、３０～３８０℃の温度範囲における平均線熱膨張係数は、好ましくは２５×１０－７～６０～１０－７／℃、２８×１０－７～５５～１０－７／℃、特に３０×１０－７～５０～１０－７／℃である。 Glass substrates for magnetic recording media are required to have an appropriate coefficient of thermal expansion in order to improve the reliability of recording and reproduction of magnetic recording media. Specifically, an HDD (hard disk drive) incorporating a magnetic recording medium has a structure in which the central portion is pressed by a spindle of a spindle motor to rotate the magnetic recording medium itself. Therefore, if the difference in thermal expansion coefficient between the glass substrate and the spindle material is too large, the thermal expansion and contraction of the two will be different in response to changes in ambient temperature, resulting in a phenomenon in which the magnetic recording medium is deformed. When such a phenomenon occurs, the written information cannot be read by the magnetic head, which may impair the reliability of recording and reproduction. Therefore, it is desirable that the glass substrate for a magnetic recording medium has a coefficient of thermal expansion that matches the coefficient of thermal expansion of the spindle material (for example, stainless steel, etc.). From this point of view, the average linear thermal expansion coefficient in the temperature range of 30 to 380°C is preferably 25 × 10 -7 to 60 to 10 -7 /°C, 28 × 10 -7 to 55 to 10 -7 /°C , especially 30×10 −7 to 50 to 10 −7 /°C.
液相温度は、好ましくは１３００℃以下、１２８０℃以下、１２６０℃以下、１２５０℃以下、１２４０℃以下、特に１２３０℃以下である。液相粘度は、好ましくは１０３．８ｄＰａ・ｓ以上、１０４．４ｄＰａ・ｓ以上、１０４．６ｄＰａ・ｓ以上、１０４．８ｄＰａ・ｓ以上、特に１０５．０ｄＰａ・ｓ以上である。このようにすれば、成形時に失透結晶が析出し難くなり、オーバーフローダウンドロー法等で板状に成形し易くなるため、表面を研磨しなくても、或いは少量の研磨によって、表面の平均表面粗さＲａを１．０ｎｍ以下、特に０．２ｎｍ以下にすることができる。結果として、ビットサイズの微細化によって磁気特性を高めることが可能になる。また失透結晶や研磨量の低減により、ガラス基板を低コスト化することができる。ここで、「液相温度」は、標準篩３０メッシュ（５００μｍ）を通過し、５０メッシュ（３００μｍ）に残るガラス粉末を白金ボートに入れた後、温度勾配炉中に２４時間保持して、結晶が析出する温度を測定することにより算出可能である。「液相粘度」は、液相温度におけるガラスの粘度を指し、白金球引き上げ法で測定可能である。 The liquidus temperature is preferably 1300°C or lower, 1280°C or lower, 1260°C or lower, 1250°C or lower, 1240°C or lower, particularly 1230°C or lower. The liquidus viscosity is preferably 10 3.8 dPa·s or more, 10 4.4 dPa·s or more, 10 4.6 dPa·s or more, 10 4.8 dPa·s or more, especially 10 5.0 dPa·s. s or more. This makes it difficult for devitrification crystals to precipitate during molding, making it easier to form into a plate shape using the overflow down-draw method. The roughness Ra can be set to 1.0 nm or less, particularly 0.2 nm or less. As a result, it becomes possible to improve magnetic properties by reducing the bit size. Further, by reducing devitrification crystals and the amount of polishing, the cost of the glass substrate can be reduced. Here, the "liquidus temperature" is defined as the glass powder that passes through a standard sieve of 30 mesh (500 μm) and remains at 50 mesh (300 μm), is placed in a platinum boat, and then held in a temperature gradient furnace for 24 hours to crystallize. It can be calculated by measuring the temperature at which it precipitates. “Liquidus viscosity” refers to the viscosity of glass at liquidus temperature, and can be measured by the platinum ball pulling method.
光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率は、好ましくは７０％以上、８０％以上、特に９０％以上である。光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率が低過ぎると、レーザー照射する際に、レーザー光が磁性層に十分に照射されず、磁性層の高Ｋｕ化を図り難くなる。 The average linear transmittance at an optical path length of 1 mm and a wavelength range of 350 to 1500 nm is preferably 70% or more, 80% or more, particularly 90% or more. If the average in-line transmittance at an optical path length of 1 mm and a wavelength range of 350 to 1500 nm is too low, the laser beam will not be sufficiently irradiated onto the magnetic layer during laser irradiation, making it difficult to increase the Ku of the magnetic layer.
β－ＯＨは、好ましくは０．３０／ｍｍ以下、０．２５／ｍｍ以下、０．２０／ｍｍ以下、０．１５／ｍｍ以下、特に０．１０／ｍｍ以下である。β－ＯＨが大き過ぎると、徐冷点が低下し易くなる。なお、β－ＯＨが小さ過ぎると、ガラス中の塩素が高い状態で推移している虞がある。よって、β－ＯＨは、好ましくは０．０１／ｍｍ以上、特に０．０２／ｍｍ以上である。 β-OH is preferably 0.30/mm or less, 0.25/mm or less, 0.20/mm or less, 0.15/mm or less, particularly 0.10/mm or less. If β-OH is too large, the annealing point tends to decrease. Note that if β-OH is too small, there is a possibility that chlorine in the glass remains high. Therefore, β-OH is preferably 0.01/mm or more, particularly 0.02/mm or more.
β－ＯＨを低下させる方法として、以下の方法が挙げられる。（１）低含水量の原料を選択する。（２）ガラス中にβ－ＯＨを低下させる成分（Ｃｌ、ＳＯ３等）を添加する。（３）炉内雰囲気中の水分量を低下させる。（４）溶融ガラス中でＮ２バブリングを行う。（５）小型溶融炉を採用する。（６）溶融ガラスの流量を多くする。（７）電気溶融法を採用する。 Examples of methods for reducing β-OH include the following methods. (1) Select raw materials with low moisture content. (2) Adding components (Cl, SO 3, etc.) that reduce β-OH to the glass. (3) Reduce the amount of moisture in the furnace atmosphere. (4) Perform N2 bubbling in the molten glass. (5) Adopt a small melting furnace. (6) Increase the flow rate of molten glass. (7) Adopt electric melting method.
ここで、「β－ＯＨ」は、ＦＴ－ＩＲを用いてガラス基板の透過率を測定し、下記の式で求めた値を指す。 Here, "β-OH" refers to a value obtained by measuring the transmittance of a glass substrate using FT-IR and using the following formula.
[数１]
β－ＯＨ＝（１／Ｘ）ｌｏｇ（Ｔ１／Ｔ２）
Ｘ：板厚（ｍｍ）
Ｔ１：参照波長３８４６ｃｍ－１における透過率（％）
Ｔ２：水酸基吸収波長３６００ｃｍ－１付近における最小透過率（％）
[Number 1]
β-OH=(1/X)log(T 1 /T 2 )
X: Plate thickness (mm)
T 1 : Transmittance (%) at reference wavelength 3846 cm −1
T 2 : Minimum transmittance (%) near hydroxyl group absorption wavelength 3600 cm −1
表面の平均表面粗さＲａは、好ましくは１．０ｎｍ以下、０．７ｎｍ以下、０．４ｎｍ以下、特に０．２ｎｍ以下である。表面の平均表面粗さＲａが大き過ぎると、高記録密度化のためにビットサイズを微細化しても、磁気特性の改善が見込めなくなる。 The average surface roughness Ra of the surface is preferably 1.0 nm or less, 0.7 nm or less, 0.4 nm or less, particularly 0.2 nm or less. If the average surface roughness Ra of the surface is too large, no improvement in magnetic properties can be expected even if the bit size is made finer for higher recording density.
板厚は、好ましくは１．５ｍｍ以下、１．２ｍｍ以下、０．２～１．０ｍｍ、特に０．３～０．９ｍｍである。板厚が厚過ぎると、所望の板厚まで研磨しなければならず、加工コストが高騰する虞がある。 The plate thickness is preferably 1.5 mm or less, 1.2 mm or less, 0.2 to 1.0 mm, particularly 0.3 to 0.9 mm. If the plate thickness is too thick, the plate must be polished to the desired thickness, which may increase processing costs.
本発明の磁気記録媒体用ガラス基板は、例えば、以下の方法で作製することができる。まず所望のガラス組成になるように調合したガラス原料を連続溶融炉に投入して、１５００～１７００℃で加熱溶融し、清澄した後、溶融ガラスを成形装置に供給した上で板状に成形し、冷却することが好ましい。板状に成形した後に、所定寸法に切断加工する方法は、周知の方法を採用することができる。ガラス基板の成形方法として、種々の方法を採択することができるが、表面平滑性を高めるために、オーバーフローダウンドロー法、スロットダウン法等を採択することが好ましい。 The glass substrate for a magnetic recording medium of the present invention can be produced, for example, by the following method. First, glass raw materials prepared to have the desired glass composition are put into a continuous melting furnace, heated and melted at 1500 to 1700°C, and after being clarified, the molten glass is fed to a forming device and formed into a plate. , preferably cooled. After forming into a plate shape, a well-known method can be used to cut the plate into a predetermined size. Various methods can be used to form the glass substrate, but in order to improve surface smoothness, it is preferable to use an overflow down-draw method, a slot-down method, or the like.
以下、本発明を実施例に基づいて説明する。なお、以下の実施例は単なる例示である。本発明は、以下の実施例に何ら限定されない。 Hereinafter, the present invention will be explained based on examples. Note that the following examples are merely illustrative. The present invention is not limited to the following examples.
表１～３は、本発明の実施例（試料Ｎｏ．１～５０）を示している。 Tables 1 to 3 show examples (sample Nos. 1 to 50) of the present invention.
まず表中のガラス組成になるように、ガラス原料を調合したガラスバッチを白金坩堝に入れた後、１５００～１７００℃で２４時間溶融、清澄、均質化を行った。ガラスバッチの溶解に際しては、白金スターラーを用いて攪拌し、均質化を行った。次いで、溶融ガラスをカーボン板上に流し出して、板状に成形した後、徐冷点付近の温度で３０分間徐冷した。得られた各ガラス基板について、３０～３８０℃の温度範囲における平均線熱膨張係数α３０～３８０℃、密度Density、β－ＯＨ、歪点Ｐｓ、徐冷点Ｔａ、軟化点Ｔｓ、高温粘度１０４．５ｄＰａ・ｓにおける温度、高温粘度１０４．０ｄＰａ・ｓにおける温度、高温粘度１０３．０ｄＰａ・ｓにおける温度、高温粘度１０２．５ｄＰａ・ｓにおける温度、液相温度ＴＬ、液相粘度logη at TL、ヤング率Young’s Modulus、ヤング率／密度で計算されるSpecific modulusを評価した。 First, a glass batch containing glass raw materials prepared to have the glass composition shown in the table was placed in a platinum crucible, and then melted, refined, and homogenized at 1500 to 1700°C for 24 hours. When melting the glass batch, it was stirred using a platinum stirrer to achieve homogenization. Next, the molten glass was poured onto a carbon plate, formed into a plate shape, and then annealed for 30 minutes at a temperature near the annealing point. For each glass substrate obtained, average linear thermal expansion coefficient α in the temperature range of 30 to 380° C, density Density, β-OH, strain point Ps, annealing point Ta, softening point Ts, high temperature viscosity 10 Temperature at 4.5 dPa・s, temperature at high temperature viscosity 10 4.0 dPa・s, temperature at high temperature viscosity 10 3.0 dPa・s, temperature at high temperature viscosity 10 2.5 dPa・s, liquidus temperature TL, Liquidus viscosity logη at TL, Young's modulus, and Specific modulus calculated from Young's modulus/density were evaluated.
３０～３８０℃の温度範囲における平均線熱膨張係数は、ディラトメーターで測定した値である。 The average linear thermal expansion coefficient in the temperature range of 30 to 380°C is a value measured with a dilatometer.
密度は、アルキメデス法によって測定した値である。 The density is a value measured by the Archimedes method.
β－ＯＨは、上記方法により測定した値である。 β-OH is a value measured by the above method.
歪点、徐冷点、軟化点は、ＡＳＴＭ Ｃ３３６及びＣ３３８の方法に基づいて測定した値である。 The strain point, annealing point, and softening point are values measured based on the methods of ASTM C336 and C338.
高温粘度１０４．５ｄＰａ・ｓ、１０４．０ｄＰａ・ｓ、１０３．０ｄＰａ・ｓ、１０２．５ｄＰａ・ｓにおける温度は、白金球引き上げ法で測定した値である。 The temperatures at high temperature viscosities of 10 4.5 dPa·s, 10 4.0 dPa·s, 10 3.0 dPa·s, and 10 2.5 dPa·s are values measured by the platinum ball pulling method.
液相温度は、標準篩３０メッシュ（篩目開き５００μｍ）を通過し、５０メッシュ（篩目開き３００μｍ）に残るガラス粉末を白金ボートに入れて、温度勾配炉中に２４時間保持して、結晶（初相）の析出する温度を測定した値である。液相粘度は、液相温度におけるガラスの粘度を白金球引き上げ法で測定した値である。 The liquidus temperature is determined by placing the glass powder that passes through a standard 30 mesh sieve (sieve opening 500 μm) and remaining on the 50 mesh (sieve opening 300 μm) into a platinum boat, holding it in a temperature gradient furnace for 24 hours, and crystallizing. This is the measured value of the temperature at which the (initial phase) precipitates. The liquidus viscosity is the value of the viscosity of the glass at the liquidus temperature measured by the platinum ball pulling method.
ヤング率は、共振法により測定した値を指す。 Young's modulus refers to a value measured by a resonance method.
表から明らかなように、試料Ｎｏ．１～５０は、徐冷点が７９６℃以上、ヤング率が８１．２ＧＰａ以上、１０２．５ｄＰａ・ｓにおける温度が１６４０℃以下であるため、磁気記録媒体用ガラス基板として好適である。 As is clear from the table, sample No. Nos. 1 to 50 have an annealing point of 796° C. or higher, a Young's modulus of 81.2 GPa or higher, and a temperature of 1640° C. or lower at 10 2.5 dPa·s, so they are suitable as glass substrates for magnetic recording media.
表中の試料Ｎｏ．１～５０のガラス組成になるように、ガラス原料を調合したガラスバッチを溶融窯に投入した後、１５００～１７００℃で２４時間溶融、清澄、均質化を行い、板厚０．６７５ｍｍになるように、オーバーフローダウンドロー法で板状に成形した。得られたガラス基板の表面の表面粗さＲａを原子間力顕微鏡（ＡＦＭ）で測定したところ、０．１０～０．２０ｎｍであった。更に、得られたガラス基板について、光路長１ｍｍ、波長範囲３５０～１５００ｎｍにおける平均直線透過率を島津製作所製分光光度計ＵＶ－３１００で測定したところ、何れも９０％以上であった。 Sample No. in the table. After putting the glass batch prepared with glass raw materials into a melting kiln so that the glass composition would be 1 to 50, it was melted, clarified, and homogenized at 1500 to 1700°C for 24 hours, and the glass batch was made to a plate thickness of 0.675 mm. Then, it was formed into a plate shape using the overflow down-draw method. The surface roughness Ra of the surface of the obtained glass substrate was measured using an atomic force microscope (AFM) and was found to be 0.10 to 0.20 nm. Furthermore, when the average linear transmittance of the obtained glass substrate was measured using a spectrophotometer UV-3100 manufactured by Shimadzu Corporation with an optical path length of 1 mm and a wavelength range of 350 to 1500 nm, all of the results were 90% or more.
Claims (5)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019212416A JP7392909B2 (en) | 2019-11-25 | 2019-11-25 | Glass substrate for magnetic recording media and magnetic recording device using the same |
| JP2023195068A JP2024014964A (en) | 2019-11-25 | 2023-11-16 | Glass substrate for magnetic recording medium and magnetic recording device using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019212416A JP7392909B2 (en) | 2019-11-25 | 2019-11-25 | Glass substrate for magnetic recording media and magnetic recording device using the same |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2023195068A Division JP2024014964A (en) | 2019-11-25 | 2023-11-16 | Glass substrate for magnetic recording medium and magnetic recording device using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2021086643A JP2021086643A (en) | 2021-06-03 |
| JP7392909B2 true JP7392909B2 (en) | 2023-12-06 |
Family
ID=76087938
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2019212416A Active JP7392909B2 (en) | 2019-11-25 | 2019-11-25 | Glass substrate for magnetic recording media and magnetic recording device using the same |
| JP2023195068A Pending JP2024014964A (en) | 2019-11-25 | 2023-11-16 | Glass substrate for magnetic recording medium and magnetic recording device using the same |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2023195068A Pending JP2024014964A (en) | 2019-11-25 | 2023-11-16 | Glass substrate for magnetic recording medium and magnetic recording device using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (2) | JP7392909B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101389301B1 (en) | 2005-02-14 | 2014-04-25 | 존슨 앤드 존슨 비젼 케어, 인코포레이티드 | A method of producing ophthalmic lenses, and an ophthalmic device |
| WO2023100893A1 (en) * | 2021-12-01 | 2023-06-08 | 日本電気硝子株式会社 | Glass substrate for magnetic recording medium, glass disk for magnetic recording medium, method for manufacturing magnetic recording medium, and method for manufacturing glass disk |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015107911A (en) | 2006-06-08 | 2015-06-11 | Hoya株式会社 | Glass for use as substrate for information recording medium, substrate for information recording medium, information recording medium, and method for producing them |
| WO2017204143A1 (en) | 2016-05-25 | 2017-11-30 | 旭硝子株式会社 | Glass for data storage medium substrates, glass substrate for data storage medium, and magnetic disk |
| JP2019032918A (en) | 2017-08-08 | 2019-02-28 | 日本電気硝子株式会社 | Glass substrate for magnetic recording medium |
| WO2019146379A1 (en) | 2018-01-23 | 2019-08-01 | 日本電気硝子株式会社 | Glass substrate and method for manufacturing same |
-
2019
- 2019-11-25 JP JP2019212416A patent/JP7392909B2/en active Active
-
2023
- 2023-11-16 JP JP2023195068A patent/JP2024014964A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015107911A (en) | 2006-06-08 | 2015-06-11 | Hoya株式会社 | Glass for use as substrate for information recording medium, substrate for information recording medium, information recording medium, and method for producing them |
| WO2017204143A1 (en) | 2016-05-25 | 2017-11-30 | 旭硝子株式会社 | Glass for data storage medium substrates, glass substrate for data storage medium, and magnetic disk |
| JP2019032918A (en) | 2017-08-08 | 2019-02-28 | 日本電気硝子株式会社 | Glass substrate for magnetic recording medium |
| WO2019146379A1 (en) | 2018-01-23 | 2019-08-01 | 日本電気硝子株式会社 | Glass substrate and method for manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2021086643A (en) | 2021-06-03 |
| JP2024014964A (en) | 2024-02-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100329001B1 (en) | High rigidity glass-ceramic substrate for a magnetic information storage medium | |
| US8394516B2 (en) | Glass substrate for magnetic recording medium and magnetic recording medium | |
| JP5708732B2 (en) | Glass for data storage medium substrate, glass substrate for data storage medium and magnetic disk | |
| US8257831B2 (en) | Glass-ceramics | |
| JP7454021B2 (en) | Glass for magnetic recording media substrates, magnetic recording media substrates, magnetic recording media, and glass spacers for magnetic recording and reproducing devices | |
| JP2024014964A (en) | Glass substrate for magnetic recording medium and magnetic recording device using the same | |
| CN105517966B (en) | glass substrate | |
| JPH07300340A (en) | Crystallized glass for information-recording disk | |
| JP4774466B1 (en) | Crystallized glass substrate for information recording medium and manufacturing method thereof | |
| JP4072275B2 (en) | Substrate for information recording medium made of crystallized glass and information recording medium | |
| JP2023166439A (en) | Glass for magnetic recording medium substrate or for glass spacer for magnetic recording/reproducing device, magnetic recording medium substrate, magnetic recording medium, glass spacer for magnetic recording/reproducing device, and magnetic recording/reproducing device | |
| JP7165655B2 (en) | Glass for information recording medium substrate, information recording medium substrate, information recording medium and glass spacer for recording/reproducing device | |
| JP7276645B2 (en) | Glass substrate for magnetic recording media | |
| WO2021246151A1 (en) | Glass disk for magnetic recording media and magnetic recording device using same | |
| JP4266095B2 (en) | Glass ceramics | |
| WO2023100893A1 (en) | Glass substrate for magnetic recording medium, glass disk for magnetic recording medium, method for manufacturing magnetic recording medium, and method for manufacturing glass disk | |
| US20050181218A1 (en) | Glass substrate for information recording media and information recording medium | |
| WO2024057890A1 (en) | Alkali-free glass plate | |
| WO2024034492A1 (en) | Non-alkali glass plate | |
| JP7488416B2 (en) | Glass for a magnetic recording medium substrate or a glass spacer for a magnetic recording/reproducing device, a magnetic recording medium substrate, a magnetic recording medium, a glass spacer for a magnetic recording/reproducing device, and a magnetic recording/reproducing device | |
| JP4795522B2 (en) | High rigidity glass ceramic substrate and information magnetic storage medium disk | |
| WO2022239742A1 (en) | Alkali-free glass panel | |
| WO2022239741A1 (en) | Alkali-free glass plate | |
| WO2023276608A1 (en) | Alkali-free glass panel | |
| JP7389545B2 (en) | Glass for magnetic recording media substrates, magnetic recording media substrates, magnetic recording media |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20221012 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20230802 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20230921 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20231010 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20231025 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20231107 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 7392909 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |