JP4867607B2 - Manufacturing method of glass substrate for information recording medium - Google Patents
Manufacturing method of glass substrate for information recording medium Download PDFInfo
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- JP4867607B2 JP4867607B2 JP2006314024A JP2006314024A JP4867607B2 JP 4867607 B2 JP4867607 B2 JP 4867607B2 JP 2006314024 A JP2006314024 A JP 2006314024A JP 2006314024 A JP2006314024 A JP 2006314024A JP 4867607 B2 JP4867607 B2 JP 4867607B2
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- 239000000758 substrate Substances 0.000 title claims description 91
- 239000011521 glass Substances 0.000 title claims description 85
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- 238000003426 chemical strengthening reaction Methods 0.000 claims description 72
- 239000007788 liquid Substances 0.000 claims description 48
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 42
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 33
- 229910001414 potassium ion Inorganic materials 0.000 claims description 31
- 229910001415 sodium ion Inorganic materials 0.000 claims description 28
- 235000010344 sodium nitrate Nutrition 0.000 claims description 21
- 239000004317 sodium nitrate Substances 0.000 claims description 21
- 150000002500 ions Chemical class 0.000 claims description 18
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 17
- 229910001416 lithium ion Inorganic materials 0.000 claims description 17
- 238000005342 ion exchange Methods 0.000 claims description 15
- 150000003839 salts Chemical class 0.000 claims description 15
- 235000010333 potassium nitrate Nutrition 0.000 claims description 14
- 239000004323 potassium nitrate Substances 0.000 claims description 14
- 238000002156 mixing Methods 0.000 claims description 9
- 239000010410 layer Substances 0.000 description 35
- 238000000034 method Methods 0.000 description 31
- 239000010408 film Substances 0.000 description 18
- 238000000227 grinding Methods 0.000 description 15
- 239000000463 material Substances 0.000 description 12
- 230000003014 reinforcing effect Effects 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 238000005498 polishing Methods 0.000 description 10
- 238000005728 strengthening Methods 0.000 description 10
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 9
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 9
- 238000004140 cleaning Methods 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000005345 chemically strengthened glass Substances 0.000 description 5
- 238000010828 elution Methods 0.000 description 5
- 238000007517 polishing process Methods 0.000 description 5
- 239000005354 aluminosilicate glass Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 239000011241 protective layer Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000003746 surface roughness Effects 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910001413 alkali metal ion Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 230000009477 glass transition Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 239000006060 molten glass Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 239000010702 perfluoropolyether Substances 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910001149 41xx steel Inorganic materials 0.000 description 1
- 229910003321 CoFe Inorganic materials 0.000 description 1
- 229910002441 CoNi Inorganic materials 0.000 description 1
- 229910018979 CoPt Inorganic materials 0.000 description 1
- 229910000684 Cobalt-chrome Inorganic materials 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 239000005407 aluminoborosilicate glass Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000005388 borosilicate glass Substances 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 239000010952 cobalt-chrome Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000012854 evaluation process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000006249 magnetic particle Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
- 239000005361 soda-lime glass Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Surface Treatment Of Glass (AREA)
- Magnetic Record Carriers (AREA)
- Manufacturing Of Magnetic Record Carriers (AREA)
Description
本発明は、化学強化処理液にガラス基板を浸漬し、ガラス基板表層のイオンを化学強化処理液中のイオンでイオン交換してガラス基板を化学強化するための化学強化処理液、該化学強化処理液を用いた情報記録媒体用ガラス基板の製造方法、該製造方法により製造した情報記録媒体用ガラス基板及び情報記録媒体に関する。 The present invention relates to a chemical strengthening treatment liquid for chemically strengthening a glass substrate by immersing a glass substrate in a chemical strengthening treatment liquid, and ion-exchanging ions on the surface of the glass substrate with ions in the chemical strengthening treatment liquid. The present invention relates to a method for producing a glass substrate for information recording medium using a liquid, a glass substrate for information recording medium produced by the production method, and an information recording medium.
磁気、光、光磁気等の性質を利用した記録層を有する情報記録媒体のなかで、代表的なものとして磁気ディスクがある。磁気ディスク用基板として、従来アルミニウム基板が広く用いられていた。しかし、近年、記録密度向上のための磁気ヘッド浮上量の低減の要請に伴い、アルミニウム基板よりも表面の平滑性に優れ、しかも表面欠陥が少ないことから磁気ヘッド浮上量の低減を図ることができるガラス基板を磁気ディスク用基板として用いる割合が増えてきている。 Among information recording media having a recording layer utilizing properties such as magnetism, light, and magnetomagnetism, a typical example is a magnetic disk. Conventionally, aluminum substrates have been widely used as magnetic disk substrates. However, in recent years, with the demand for a reduction in the flying height of the magnetic head for improving the recording density, the surface smoothness is superior to that of an aluminum substrate and the surface defects are few, so that the flying height of the magnetic head can be reduced. The proportion of using glass substrates as magnetic disk substrates is increasing.
このような磁気ディスク等の情報記録媒体用ガラス基板の製造方法においては、ガラス基板の耐衝撃性や耐振動性を向上させ衝撃や振動によって基板が破損するのを防止する目的で、ガラス基板の表面に化学強化処理を施して基板を強化することが一般的に行われている。 In such a method for producing a glass substrate for an information recording medium such as a magnetic disk, for the purpose of improving the impact resistance and vibration resistance of the glass substrate and preventing the substrate from being damaged by impact and vibration, In general, a substrate is strengthened by applying a chemical strengthening treatment to the surface.
化学強化処理は、通常、化学強化処理液にガラス基板を浸漬し、ガラス基板表層のイオンを化学強化処理液中のイオンでイオン交換してガラス基板を化学強化するイオン交換法によって行われる。 The chemical strengthening treatment is usually performed by an ion exchange method in which a glass substrate is immersed in a chemical strengthening treatment liquid, and ions on the surface of the glass substrate are ion exchanged with ions in the chemical strengthening treatment liquid to chemically strengthen the glass substrate.
イオン交換によってガラス基板を化学強化するための化学強化処理液として、硝酸カリウム（ＫＮＯ3）、硝酸ナトリウム（ＮａＮＯ3）、炭酸カリウム（Ｋ2ＣＯ3）などの溶融塩や、これらの塩を混合したもの（例えば、ＫＮＯ3＋ＮａＮＯ3、ＫＮＯ3＋Ｋ2ＣＯ3など）の溶融塩などが知られている（例えば、特許文献１を参照。）。更に、特許文献１では、硝酸カリウム（６０％）と硝酸ナトリウム（４０％）を混合した化学強化処理液が記載されている。
しかしながら、従来の化学強化処理液（例えば、硝酸カリウム（６０％）と硝酸ナトリウム（４０％）を混合した化学強化処理液）を用いて化学強化を行ったガラス基板に磁性層等の膜を形成した磁気ディスクは、高温高湿の環境下（例えば５０〜１００℃、３０％〜７０％）に曝されると、膜が斑点状あるいはすじ状に白く変色する現象（以下、「膜の白濁」という。）が現れることがあった。 However, a film such as a magnetic layer is formed on a glass substrate subjected to chemical strengthening using a conventional chemical strengthening treatment liquid (for example, a chemical strengthening treatment liquid in which potassium nitrate (60%) and sodium nitrate (40%) are mixed). When a magnetic disk is exposed to a high-temperature and high-humidity environment (for example, 50 to 100 ° C., 30% to 70%), the film turns white in spots or streaks (hereinafter referred to as “film cloudiness”). .) Sometimes appeared.
本発明者が鋭意検討を重ねた結果、この膜の白濁は、化学強化処理されたガラス基板の表面から溶出したリチウムイオンが、表面に形成された保護層や磁性層等の薄膜材料と反応したものであることが判明した。更に、この膜の白濁が進行すると磁性層の劣化につながり、外観上の問題のみならず磁気ディスクとしての性能上大きな問題となることが分かった。 As a result of extensive studies by the present inventors, the cloudiness of this film was caused by the reaction of lithium ions eluted from the surface of the chemically strengthened glass substrate with thin film materials such as a protective layer and a magnetic layer formed on the surface. Turned out to be. Furthermore, it has been found that when the cloudiness of the film progresses, the magnetic layer is deteriorated, which becomes a problem not only in appearance but also in performance as a magnetic disk.
近年は磁気ディスクの用途が拡大し、オフィスに設置される機器のみならず、持ち歩いて使用するポータブル機器や車載用機器等にも磁気ディスクが採用されるケースが多くなっている。そのため、磁気ディスクに要求される信頼性、耐環境性もますます高くなり、膜の白濁の発生は大きな問題となっていた。 In recent years, the use of magnetic disks has expanded, and in many cases, magnetic disks are employed not only in devices installed in offices, but also in portable devices and in-vehicle devices that are carried around. For this reason, the reliability and environmental resistance required for magnetic disks are increasing, and the occurrence of cloudiness in the film has been a major problem.
本発明は上記のような技術的課題に鑑みてなされたものであり、本発明の目的は、化学強化処理されたガラス基板の表面からのリチウムイオンの溶出量を最小限に抑えることで、高温多湿の環境下に曝された場合であっても膜の白濁の発生を防止し、高い信頼性を有する情報記録媒体用ガラス基板の製造方法を提供することである。 The present invention has been made in view of the above technical problems, and an object of the present invention is to minimize the elution amount of lithium ions from the surface of a chemically strengthened glass substrate, thereby increasing the temperature. An object of the present invention is to provide a method for producing a glass substrate for an information recording medium that prevents the occurrence of white turbidity in a film even when exposed to a humid environment and has high reliability.
上記の課題を解決するために、本発明は以下の特徴を有するものである。 In order to solve the above problems, the present invention has the following features.
１． 化学強化処理液にガラス基板を浸漬し、ガラス基板表層のイオンを化学強化処理液中のイオンでイオン交換してガラス基板を化学強化する工程を含む情報記録媒体用ガラス基板の製造方法において、前記ガラス基板は、リチウムイオンを成分として含有するガラス基板であり、前記化学強化処理液は、ナトリウムイオン及びカリウムイオンを含む溶融塩であって、前記化学強化処理液に含まれるナトリウムイオン／カリウムイオンのモル比が０．０１〜０．１２であり、前記化学強化する工程は、該化学強化処理液のみを用いて行われることを特徴とする情報記録媒体用ガラス基板の製造方法。 1. In the method for producing a glass substrate for an information recording medium, comprising the steps of immersing the glass substrate in a chemical strengthening treatment liquid, and ion-exchanging ions on the surface of the glass substrate with ions in the chemical strengthening treatment liquid to chemically strengthen the glass substrate. The glass substrate is a glass substrate containing lithium ions as a component, and the chemical strengthening treatment liquid is a molten salt containing sodium ions and potassium ions, and includes sodium ions / potassium ions contained in the chemical strengthening treatment liquid. The method for producing a glass substrate for an information recording medium , wherein the molar ratio is 0.01 to 0.12, and the chemical strengthening step is performed using only the chemical strengthening treatment liquid .
２． 前記化学強化処理液は、硝酸カリウム及び硝酸ナトリウムからなる混合溶融塩であり、その混合比が、硝酸カリウム１００質量部に対して、硝酸ナトリウム１質量部〜１０質量部であることを特徴とする前記１に記載の情報記録媒体用ガラス基板の製造方法。 2. The chemical strengthening treatment liquid is a mixed molten salt composed of potassium nitrate and sodium nitrate, and the mixing ratio thereof is 1 part by mass to 10 parts by mass of sodium nitrate with respect to 100 parts by mass of potassium nitrate. The manufacturing method of the glass substrate for information recording media as described in 2 ..
本発明によれば、化学強化処理されたガラス基板の表面からのリチウムイオンの溶出量を最小限に抑えることで、高温多湿の環境下に曝された場合であっても膜の白濁の発生を防止し、高い信頼性を有する情報記録媒体用ガラス基板の製造方法を提供することができる。 According to the present invention, by suppressing the elution amount of lithium ions from the surface of the chemically strengthened glass substrate, the occurrence of cloudiness of the film can be achieved even when exposed to a high temperature and humidity environment. The manufacturing method of the glass substrate for information recording media which can prevent and has high reliability can be provided.
以下、本発明の実施の形態について詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail.
（情報記録媒体用ガラス基板の製造方法）
情報記録媒体用ガラス基板は、一般的に、ブランク材作製工程、内外周加工工程、研削・研磨工程、化学強化工程、洗浄工程などの工程を経て製造される。ブランク材作製工程は情報記録媒体用ガラス基板の基になるブランク材を形成する工程であり、溶融ガラスをプレス成形して作製する方法や、シート状のガラスを切断して作製する方法が知られている。内外周加工工程は、中心孔の穿孔加工、内外周の形状や寸法精度確保のための研削加工、内外周の研磨加工等を行う工程である。研削・研磨工程は、記録層が形成される面の平坦度、表面粗さを満足させるための研削加工、研磨加工を行う工程である。通常は、粗研削加工、精研削加工、１次研磨加工、２次研磨加工といったようにいくつかの段階に分けて行われる場合が多い。化学強化工程は、化学強化処理液にガラス基板を浸漬することでガラス基板を強化する工程である。また、洗浄工程は、ガラス基板の表面に残った研磨剤や化学強化処理液等の異物を除去する工程である。
(Method for producing glass substrate for information recording medium)
The glass substrate for information recording media is generally manufactured through processes such as a blank material manufacturing process, an inner and outer peripheral processing process, a grinding / polishing process, a chemical strengthening process, and a cleaning process. The blank material production process is a process for forming a blank material that is the basis of a glass substrate for information recording media, and a method of producing a molten glass by press molding or a method of producing by cutting a sheet-like glass is known. ing. The inner and outer peripheral machining step is a step of performing drilling of the center hole, grinding for ensuring the shape and dimensional accuracy of the inner and outer circumferences, polishing of the inner and outer circumferences, and the like. The grinding / polishing step is a step of performing grinding and polishing to satisfy the flatness and surface roughness of the surface on which the recording layer is formed. Usually, it is often performed in several stages such as rough grinding, fine grinding, primary polishing, and secondary polishing. The chemical strengthening step is a step of strengthening the glass substrate by immersing the glass substrate in the chemical strengthening treatment liquid. The cleaning step is a step of removing foreign matters such as abrasives and chemical strengthening treatment liquid remaining on the surface of the glass substrate.
本発明の情報記録媒体用ガラス基板の製造方法は、これらの工程の内、主に化学強化工程に特徴を有するものである。本発明においては、研削・研磨工程が完了した後に化学強化工程を行っても良いし、先に化学強化工程を行ってから研削・研磨工程を行ってもよい。また、研削・研磨工程がある段階まで進んだ時点で化学強化工程を行い、その後に研削・研磨工程の残りの工程を行って仕上げることもできる。 The manufacturing method of the glass substrate for information recording media of this invention has the characteristics mainly in the chemical strengthening process among these processes. In the present invention, the chemical strengthening step may be performed after the grinding / polishing step is completed, or the grinding / polishing step may be performed after the chemical strengthening step is performed first. Alternatively, the chemical strengthening process may be performed when the grinding / polishing process has progressed to a certain stage, and then the remaining processes of the grinding / polishing process may be performed.
化学強化工程の後に研削・研磨工程を行うか否かに拘わらず、イオン交換が行われて強化された領域（以下、「強化層」という。）の上に磁性層等の薄膜を形成する場合は、本発明を好ましく適用できる。また、化学強化工程の後の研削・研磨工程によって強化層が除去された後の表面に磁性層等の薄膜を形成する場合であっても、内外周の端面には強化層が残存するのが一般的であり、本発明によってそのような残存強化層からのリチウムイオンの溶出を防止することができ、膜の白濁を防止する効果が得られる。 When a thin film such as a magnetic layer is formed on a region strengthened by ion exchange (hereinafter referred to as “strengthening layer”) regardless of whether the grinding / polishing step is performed after the chemical strengthening step. The present invention can be preferably applied. Even when a thin film such as a magnetic layer is formed on the surface after the reinforcing layer is removed by the grinding / polishing process after the chemical strengthening process, the reinforcing layer may remain on the inner and outer peripheral end faces. In general, according to the present invention, the elution of lithium ions from such a remaining reinforcing layer can be prevented, and the effect of preventing the cloudiness of the film can be obtained.
なお、本発明の情報記録媒体用ガラス基板の製造方法においては、上記以外の種々の工程を有していても良い。例えば、ガラス基板の内部歪みを緩和するためのアニール工程、ガラス基板の強度の信頼性確認のためのヒートショック工程、種々の検査・評価工程等を有していても良い。 In addition, in the manufacturing method of the glass substrate for information recording media of this invention, you may have various processes other than the above. For example, an annealing process for relaxing internal strain of the glass substrate, a heat shock process for confirming the reliability of the strength of the glass substrate, various inspection / evaluation processes, and the like may be included.
（化学強化処理液と化学強化工程）
化学強化工程は、加熱された化学強化処理液にガラス基板を浸漬することによってガラス基板の成分であるリチウムイオン、ナトリウムイオン等のアルカリ金属イオンをこれらのイオンよりイオン半径の大きなナトリウムイオン、カリウムイオン等のアルカリ金属イオンと置換するイオン交換法によって行われる。イオン半径の違いによって生じる歪みより、イオン交換された領域に圧縮応力が発生し、ガラス基板の表面が強化される。なお、イオン半径を比較すると、リチウムイオン＜ナトリウムイオン＜カリウムイオンとなる。
(Chemical strengthening treatment liquid and chemical strengthening process)
In the chemical strengthening process, by immersing the glass substrate in a heated chemical strengthening solution, alkali metal ions such as lithium ions and sodium ions that are components of the glass substrate are converted into sodium ions and potassium ions having a larger ion radius than these ions. It is carried out by an ion exchange method for substituting alkali metal ions such as. Compressive stress is generated in the ion-exchanged region due to distortion caused by the difference in ion radius, and the surface of the glass substrate is strengthened. When the ionic radii are compared, lithium ion <sodium ion <potassium ion.
化学強化処理液として、ナトリウムイオンやカリウムイオンを含む溶融塩を用いることが一般的であるが、本発明者は、化学強化処理液として、ナトリウムイオン及びカリウムイオンを含む溶融塩であり、ナトリウムイオン／カリウムイオンのモル比が０．０１〜０．６の範囲のものを用いることで、化学強化処理されたガラス基板の表面からのリチウムイオンの溶出量を最小限に抑え、高温多湿の環境下に曝された場合であっても膜の白濁の発生を防止することができることを見いだした。 Although it is common to use a molten salt containing sodium ions and potassium ions as the chemical strengthening treatment liquid, the present inventor is a molten salt containing sodium ions and potassium ions as the chemical strengthening treatment liquid. / Mass ratio of potassium ions in the range of 0.01-0.6 minimizes the elution amount of lithium ions from the surface of the chemically strengthened glass substrate, in a high temperature and high humidity environment It has been found that the occurrence of white turbidity of the film can be prevented even when exposed to.
このような化学強化処理液を用いることで化学強化処理されたガラス基板の表面からのリチウムイオンの溶出量が抑えられる理由については、必ずしも明らかではないが、以下のように予想される。化学強化処理によってガラス基板の表面に入り込むイオンのうち、ナトリウムイオンの割合が多い場合、ガラス基板が高温多湿の環境下に曝されると、表面のナトリウムイオンが徐々に溶出して微細な空隙が生じ、ガラス基板の内部に存在するリチウムイオンが空隙を通って表面から溶出しやすくなる。これに対し、カリウムイオンはナトリウムイオンよりもイオン半径が大きいためにガラス基板内部で動きにくく、ガラス基板が高温多湿の環境下に曝されても表面に溶出しにくい。そのため、化学強化処理によってガラス基板の表面に入り込むイオンのうち、カリウムイオンの割合が多い場合、ガラス基板の内部に存在するリチウムイオンが動くための空隙が発生しにくく、リチウムイオンは溶出しにくいのではないかと考えられる。 The reason why the elution amount of lithium ions from the surface of the chemically strengthened glass substrate can be suppressed by using such a chemical strengthening treatment liquid is not necessarily clear, but is expected as follows. When the proportion of sodium ions out of the ions entering the surface of the glass substrate by chemical strengthening treatment is high, when the glass substrate is exposed to a high temperature and humidity environment, the sodium ions on the surface gradually elute and fine voids are formed. As a result, the lithium ions existing inside the glass substrate are easily eluted from the surface through the voids. On the other hand, potassium ions have a larger ion radius than sodium ions, so that they do not easily move inside the glass substrate, and even if the glass substrate is exposed to a high temperature and high humidity environment, it is difficult to elute on the surface. Therefore, among the ions that enter the surface of the glass substrate by chemical strengthening treatment, when there is a large proportion of potassium ions, voids for movement of lithium ions existing inside the glass substrate are not easily generated, and lithium ions are difficult to elute. It is thought that.
化学強化処理によってガラス基板の表面に入り込むイオンのうち、カリウムイオンの割合を増やすためには、化学強化処理液中のナトリウムイオン／カリウムイオンのモル比を小さくすれば良い。本発明者による鋭意検討の結果、ナトリウムイオン／カリウムイオンのモル比を０．６以下とすることで、膜の白濁を防止できることが分かった。また、ナトリウムイオン／カリウムイオンのモル比を０．３以下とすることが更に好ましい。 In order to increase the proportion of potassium ions among the ions that enter the surface of the glass substrate by the chemical strengthening treatment, the molar ratio of sodium ions / potassium ions in the chemical strengthening treatment solution may be reduced. As a result of intensive studies by the present inventor, it was found that the white turbidity of the film can be prevented by setting the molar ratio of sodium ion / potassium ion to 0.6 or less. The molar ratio of sodium ion / potassium ion is more preferably 0.3 or less.
一方、ナトリウムイオン／カリウムイオンのモル比を小さくしすぎると、カリウムイオンがガラス表面に入り込みにくくなり、強化が進まないという問題が発生する。これは、ガラス表面から溶出するリチウムイオンと、ガラス表面に入り込もうとするカリウムイオンのイオン半径の差が大きすぎ、イオン交換がスムーズに進行しないためと考えられる。ところが、化学強化処理液中にナトリウムイオンが存在すると、リチウムイオンが抜けた空隙に一旦ナトリウムイオンが入り込み、その後再びナトリウムイオンが溶出して最終的にカリウムイオンが入り込むという現象が起こり、リチウムイオンとカリウムイオンとのイオン交換がスムーズに進行することが判明した。具体的には、化学強化処理液中のナトリウムイオン／カリウムイオンのモル比が０．０１以上であればイオン交換をスムーズに進行させることができる。また、ナトリウムイオン／カリウムイオンのモル比が０．０５以上であることが更に好ましい。 On the other hand, when the molar ratio of sodium ions / potassium ions is too small, potassium ions are difficult to enter the glass surface, resulting in a problem that strengthening does not proceed. This is presumably because the difference in ion radius between lithium ions eluted from the glass surface and potassium ions trying to enter the glass surface is too large and ion exchange does not proceed smoothly. However, when sodium ions are present in the chemical strengthening treatment solution, sodium ions once enter the voids from which lithium ions have escaped, and then sodium ions elute again and finally potassium ions enter. It was found that ion exchange with potassium ions proceeds smoothly. Specifically, if the molar ratio of sodium ions / potassium ions in the chemical strengthening treatment liquid is 0.01 or more, ion exchange can proceed smoothly. The molar ratio of sodium ion / potassium ion is more preferably 0.05 or more.
このように、化学強化処理によってガラス基板の表面に入り込むイオンのうち、カリウムイオンの割合を多くすると共に、リチウムイオンとカリウムイオンとのイオン交換をスムーズに進行させるという観点から、化学強化処理液中のナトリウムイオン／カリウムイオンのモル比は、０．０１〜０．６の範囲であることが必要であり、０．０５〜０．３の範囲が特に好ましい。但し、請求項１に記載の発明では、ナトリウムイオン／カリウムイオンのモル比を０．０１〜０．１２とする。 In this way, in the chemical strengthening treatment liquid, from the viewpoint of increasing the proportion of potassium ions among the ions entering the surface of the glass substrate by the chemical strengthening treatment and smoothly proceeding the ion exchange between lithium ions and potassium ions. The sodium ion / potassium ion molar ratio must be in the range of 0.01 to 0.6, particularly preferably in the range of 0.05 to 0.3. However, in the invention according to claim 1, the molar ratio of sodium ion / potassium ion is set to 0.01 to 0.12.
ナトリウムイオン及びカリウムイオンを含む溶融塩としては、ナトリウムやカリウムの硝酸塩、炭酸塩、硫酸塩などの混合溶融塩が挙げられるが、融点が低く、ガラス基板の変形を防止できるという観点から、硝酸ナトリウム（ＮａＮＯ３）と硝酸カリウム（ＫＮＯ３）の混合溶融塩を用いることが好ましい。この場合、混合溶融塩中のナトリウムイオン／カリウムイオンのモル比を上記範囲とする観点から、硝酸ナトリウムと硝酸カリウムの混合比は、硝酸カリウム１００質量部に対して、硝酸ナトリウム１質量部〜５０質量部であることが好ましく、硝酸ナトリウム５質量部〜２５質量部であることが特に好ましい。硝酸ナトリウムが１質量部未満であるとイオン交換がスムーズに行われず、強化が進行しにくい。また、硝酸ナトリウムが５０質量部よりも多いと膜の白濁が発生し易い。但し、請求項２に記載の発明では、硝酸ナトリウムと硝酸カリウムの混合比は、硝酸カリウム１００質量部に対して、硝酸ナトリウム１質量部〜１０質量部とする。 Examples of the molten salt containing sodium ions and potassium ions include mixed molten salts such as nitrates, carbonates, and sulfates of sodium and potassium. From the viewpoint that the melting point is low and deformation of the glass substrate can be prevented. It is preferable to use a mixed molten salt of (NaNO 3 ) and potassium nitrate (KNO 3 ). In this case, from the viewpoint of setting the molar ratio of sodium ions / potassium ions in the mixed molten salt to the above range, the mixing ratio of sodium nitrate and potassium nitrate is 1 part by mass to 50 parts by mass of sodium nitrate with respect to 100 parts by mass of potassium nitrate. It is preferable that it is 5 mass parts-25 mass parts of sodium nitrate. When the sodium nitrate is less than 1 part by mass, ion exchange is not performed smoothly, and strengthening is difficult to proceed. Moreover, when there is more sodium nitrate than 50 mass parts, the cloudiness of a film | membrane tends to generate | occur | produce. However, in invention of Claim 2, the mixing ratio of sodium nitrate and potassium nitrate shall be 1 mass part-10 mass parts of sodium nitrate with respect to 100 mass parts of potassium nitrate.
化学強化処理液は、上記の成分が融解する温度よりも高温になるよう加熱される。一方、化学強化処理液の加熱温度が高すぎると、ガラス基板の温度が上がりすぎ、ガラス基板の変形を招く虞がある。このため、化学強化処理液の加熱温度はガラス基板のガラス転移点（Ｔｇ）よりも低い温度が好ましく、ガラス転移点−５０℃よりも低い温度とすることが更に好ましい。 The chemical strengthening treatment liquid is heated to a temperature higher than the temperature at which the above components melt. On the other hand, if the heating temperature of the chemical strengthening treatment liquid is too high, the temperature of the glass substrate is excessively increased, and the glass substrate may be deformed. For this reason, the heating temperature of the chemical strengthening treatment liquid is preferably lower than the glass transition point (Tg) of the glass substrate, more preferably lower than the glass transition point −50 ° C.
強化層の厚みは、ガラス基板と化学強化処理液の温度、及び浸漬時間等によって決まる。情報記録媒体用ガラス基板として必要な堅さ、強度、表面粗さを備えるという観点から、強化層の厚みは、研削・研磨工程が完了した後に化学強化工程を行う場合は５μｍ〜２００μｍ、化学強化工程の後、更に研削・研磨工程を行う場合は、１０μｍ〜５００μｍの範囲が好ましい。このような強化層の厚みを得るために必要な浸漬時間は、通常、０．５時間〜２０時間程度となる。 The thickness of the reinforcing layer is determined by the temperature of the glass substrate and the chemical strengthening treatment liquid, the immersion time, and the like. From the viewpoint of providing the necessary rigidity, strength and surface roughness as a glass substrate for information recording media, the thickness of the reinforcing layer is 5 μm to 200 μm when the chemical strengthening process is performed after the grinding / polishing process is completed. When a grinding / polishing step is further performed after the step, a range of 10 μm to 500 μm is preferable. The immersion time necessary to obtain such a thickness of the reinforcing layer is usually about 0.5 to 20 hours.
なお、加熱された化学強化処理液に浸漬される際の熱衝撃によるガラス基板の割れや微細なクラックの発生を防止するため、化学強化処理液への浸漬に先立って、予熱槽でガラス基板を所定温度に加熱する予熱工程を有していても良い。 In addition, in order to prevent the occurrence of cracks and fine cracks in the glass substrate due to thermal shock when immersed in the heated chemical strengthening treatment liquid, the glass substrate is placed in a preheating tank prior to immersion in the chemical strengthening treatment liquid. You may have the preheating process heated to predetermined temperature.
（洗浄工程）
化学強化処理工程の後、ガラス基板の表面に残存する化学強化処理液等を十分に除去するため、ガラス基板の洗浄を行うのが一般的である。
(Washing process)
After the chemical strengthening treatment step, the glass substrate is generally washed in order to sufficiently remove the chemical strengthening treatment liquid remaining on the surface of the glass substrate.
洗浄液に特に制限はなく、水、有機溶剤、界面活性剤を含んだ各種洗浄剤等の公知の洗浄液の中から適宜選択して用いることができる。特に水は、化学強化処理液が結晶化した微粒子を溶解することが容易であるため好ましく、異物の付着を防止する観点から、フィルタリングした純水、イオン交換水、超純水などが特に好ましい。結晶化した微粒子の溶解度を更に上げるため、３０〜８０℃程度に加熱した温水を用いることも好ましい。また、洗浄工程は、複数の洗浄槽を用いて複数段階に分けて行うこともできる。更に、ガラス基板を洗浄液に浸漬するだけではなく、超音波を加えても良いし、ブラシやスポンジ等でガラス基板の表面を擦るスクラブ式の洗浄を行っても良い。 There is no restriction | limiting in particular in a washing | cleaning liquid, It can select suitably from well-known washing | cleaning liquids, such as various cleaning agents containing water, an organic solvent, and surfactant, and can use. In particular, water is preferable because the chemical strengthening treatment liquid can easily dissolve crystallized fine particles, and filtered pure water, ion-exchanged water, ultrapure water, and the like are particularly preferable from the viewpoint of preventing adhesion of foreign substances. In order to further increase the solubility of the crystallized fine particles, it is also preferable to use hot water heated to about 30 to 80 ° C. Further, the cleaning process can be performed in a plurality of stages using a plurality of cleaning tanks. In addition to immersing the glass substrate in the cleaning liquid, ultrasonic waves may be applied, or scrub cleaning may be performed by rubbing the surface of the glass substrate with a brush or sponge.
（ガラス基板）
本発明においては、化学強化処理液に浸漬することでイオン交換が可能なガラス基板であって、リチウムイオンを成分として含有するガラス基板を対象としている。例えば、アルミノシリケートガラス、ソーダライムガラス、ソーダアルミノケイ酸ガラス、アルミノボロシリケートガラス、ボロシリケートガラスなどが挙げられる。中でも、アルミノシリケートガラスは、耐衝撃性や耐振動性に優れるため特に好ましい。
(Glass substrate)
In this invention, it is the glass substrate which is ion-exchangeable by being immersed in a chemical strengthening process liquid, Comprising: The glass substrate containing a lithium ion as a component is made into object. Examples thereof include aluminosilicate glass, soda lime glass, soda aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, and the like. Among these, aluminosilicate glass is particularly preferable because it is excellent in impact resistance and vibration resistance.
ガラス基板の大きさに限定はない。例えば、外径が２．５インチ、１．８インチ、１インチ、０．８インチなど種々の大きさのガラス基板を用いることができる。また、ガラス基板の厚みにも限定はない。例えば、２ｍｍ、１ｍｍ、０．６３ｍｍなど種々の厚みのガラス基板を用いることができる。 There is no limitation on the size of the glass substrate. For example, glass substrates having various sizes such as 2.5 inches, 1.8 inches, 1 inch, and 0.8 inches can be used. Moreover, there is no limitation also on the thickness of a glass substrate. For example, glass substrates having various thicknesses such as 2 mm, 1 mm, and 0.63 mm can be used.
（情報記録媒体）
本発明の方法により得られた情報記録媒体用ガラス基板の上に、少なくとも記録層を形成することで情報記録媒体を得ることができる。記録層は特に限定されず、磁気、光、光磁気等の性質を利用した種々の記録層を用いることができるが、特に磁性層を記録層として用いた情報記録媒体（磁気ディスク）の製造に好適である。
(Information recording medium)
An information recording medium can be obtained by forming at least a recording layer on the glass substrate for information recording medium obtained by the method of the present invention. The recording layer is not particularly limited, and various recording layers utilizing properties such as magnetism, light, and magnetomagnetism can be used. In particular, for the production of an information recording medium (magnetic disk) using the magnetic layer as a recording layer. Is preferred.
磁性層に用いる磁性材料としては、特に限定はなく公知の材料を適宜選択して用いることができる。例えば、Ｃｏを主成分とするＣｏＰｔ、ＣｏＣｒ、ＣｏＮｉ、ＣｏＮｉＣｒ、ＣｏＣｒＴａ、ＣｏＰｔＣｒ、ＣｏＮｉＰｔ、ＣｏＮｉＣｒＰｔ、ＣｏＮｉＣｒＴａ、ＣｏＣｒＰｔＴａ、ＣｏＣｒＰｔＳｉＯなどが挙げられる。また、磁性層を非磁性膜（例えば、Ｃｒ、ＣｒＭｏ、ＣｒＶなど）で分割してノイズの低減を図った多層構成としてもよい。 The magnetic material used for the magnetic layer is not particularly limited, and a known material can be appropriately selected and used. Examples thereof include CoPt, CoCr, CoNi, CoNiCr, CoCrTa, CoPtCr, CoNiPt, CoNiCrPt, CoNiCrTa, CoCrPtTa, and CoCrPtSiO containing Co as a main component. The magnetic layer may be divided by a nonmagnetic film (for example, Cr, CrMo, CrV, etc.) to have a multilayer structure in which noise is reduced.
磁性層として、上記のＣｏ系材料の他、フェライト系や鉄−希土類系の材料や、ＳｉＯ2、ＢＮなどからなる非磁性膜中にＦｅ、Ｃｏ、ＣｏＦｅ、ＣｏＮｉＰｔ等の磁性粒子が分散された構造のグラニュラーなどを用いることもできる。磁性層は、面内型、垂直型の何れであっても良い。 As the magnetic layer, in addition to the above-mentioned Co-based material, ferrite or iron - and material of the rare earth-based, Fe, Co, CoFe, magnetic particles such CoNiPt are dispersed in a non-magnetic film made of SiO 2, BN A granular structure can also be used. The magnetic layer may be either an in-plane type or a vertical type.
磁性膜の形成方法としては、公知の方法を用いることがでる。例えば、スパッタリング法、無電解メッキ法、スピンコート法などが挙げられる。 As a method for forming the magnetic film, a known method can be used. For example, a sputtering method, an electroless plating method, a spin coating method, and the like can be given.
磁気ディスクには、更に必要により下地層、保護層、潤滑層等を設けても良い。これらの層はいずれも公知の材料を適宜選択して用いることができる。下地層の材料としては、例えば、Ｃｒ、Ｍｏ、Ｔａ、Ｔｉ、Ｗ、Ｖ、Ｂ、Ａｌ、Ｎｉなどが挙げられる。保護層の材料としては、例えば、Ｃｒ、Ｃｒ合金、Ｃ、ＺｒＯ2、ＳｉＯ2などが挙げられる。また、潤滑層としては、例えば、パーフロロポリエーテル（ＰＦＰＥ）等からなる液体潤滑剤を塗布し、必要に応じ加熱処理を行ったものなどが挙げられる。 The magnetic disk may further be provided with an underlayer, a protective layer, a lubricating layer, etc., if necessary. Any of these layers can be used by appropriately selecting a known material. Examples of the material for the underlayer include Cr, Mo, Ta, Ti, W, V, B, Al, and Ni. Examples of the material for the protective layer include Cr, Cr alloy, C, ZrO 2 , and SiO 2 . Moreover, as a lubrication layer, the thing etc. which apply | coated the liquid lubricant which consists of perfluoro polyether (PFPE) etc., and heat-processed as needed are mentioned, for example.
（実施例１）
ガラス材料としてアルミノシリケートガラスを用い、溶融ガラスをプレス成形してブランク材を作製した。内外周加工工程、研削・研磨工程を経て、外径６５ｍｍ、内径２０ｍｍ、厚み０．６３５ｍｍのガラス基板とした。表面粗さは、表裏ともに算術平均高さＲａ（ＪＩＳ Ｂ０６０１：２００１）が０．４〜０．５ｎｍとなるように仕上げた。
Example 1
Aluminosilicate glass was used as the glass material, and the blank glass was produced by press molding the molten glass. The glass substrate having an outer diameter of 65 mm, an inner diameter of 20 mm, and a thickness of 0.635 mm was obtained through an inner and outer peripheral processing step and a grinding / polishing step. The surface roughness was finished so that the arithmetic average height Ra (JIS B0601: 2001) was 0.4 to 0.5 nm on both sides.
化学強化処理液として、硝酸ナトリウム（ＮａＮＯ3）と硝酸カリウム（ＫＮＯ3）の混合溶融塩を用意した。混合比は、硝酸カリウム１００質量部に対して、硝酸ナトリウム１０質量部とした。このときのナトリウムイオン／カリウムイオンのモル比は約０．１２となる。化学強化処理液の加熱温度は３７０℃とした。 A mixed molten salt of sodium nitrate (NaNO 3 ) and potassium nitrate (KNO 3 ) was prepared as a chemical strengthening treatment liquid. The mixing ratio was 10 parts by mass of sodium nitrate with respect to 100 parts by mass of potassium nitrate. At this time, the molar ratio of sodium ion / potassium ion is about 0.12. The heating temperature of the chemical strengthening treatment liquid was 370 ° C.
ガラス基板２０枚を１つの搬送治具にセットし、３７０℃に加熱した予熱槽に投入して予熱を行った後、化学強化処理液に浸漬した。浸漬時間は２時間とした。その後、洗浄槽に貯留した純水に浸漬し、ガラス基板に付着した化学強化処理液等を除去した。純水温度は６０℃とし、洗浄槽に超音波を付加した。 20 glass substrates were set in one conveyance jig, put in a preheating tank heated to 370 ° C., preheated, and then immersed in a chemical strengthening treatment solution. The immersion time was 2 hours. Then, the chemical strengthening process liquid etc. which were immersed in the pure water stored in the washing tank and adhered to the glass substrate were removed. The pure water temperature was 60 ° C., and ultrasonic waves were added to the cleaning tank.
得られたガラス基板のうち、１０枚の基板を切断して強化層の厚みを測定した。ここでは、切断した断面を偏光顕微鏡で観察してイオン交換により歪んだ領域の深さを測定し、これを強化層の厚みとした。強化層の厚みが１００μｍ以上であればイオン交換がスムーズに進行したと考えられる。 Of the obtained glass substrates, 10 substrates were cut to measure the thickness of the reinforcing layer. Here, the cut section was observed with a polarizing microscope, the depth of the region distorted by ion exchange was measured, and this was taken as the thickness of the reinforcing layer. If the thickness of the reinforcing layer is 100 μm or more, it is considered that ion exchange proceeded smoothly.
さらに、残った１０枚のガラス基板の表面にＣｒからなる下地層（８０ｎｍ）、ＣｏＮｉＣｒからなる磁性層（４０ｎｍ）、Ｃからなる保護層（１０ｎｍ）をスパッタリング法により形成して磁気ディスクを作製した。 Further, a magnetic disk was manufactured by forming an underlayer (80 nm) made of Cr, a magnetic layer (40 nm) made of CoNiCr, and a protective layer (10 nm) made of C on the surface of the remaining 10 glass substrates by sputtering. .
作製した磁気ディスクを７０℃、８０％の環境下に１００時間置いた後、光学顕微鏡によって膜の白濁を評価した。評価は、磁気ディスク１枚当たりに発生した１０μｍ以上の大きさの白濁の個数によって行い、１０個未満であれば良好（○）、１０個以上の場合は問題あり（×）と判断した。 The produced magnetic disk was placed in an environment of 70 ° C. and 80% for 100 hours, and the cloudiness of the film was evaluated by an optical microscope. The evaluation was performed based on the number of white turbidity having a size of 10 μm or more generated per magnetic disk, and it was determined that the number was less than 10 (good) and the case of 10 or more was problematic (×).
評価結果を表１に示す。強化層の厚みは１２０μｍ（１０枚の平均値）また、白濁の数は１枚当たり２個であり、良好に強化が行われたことが確認された。 The evaluation results are shown in Table 1. The thickness of the reinforcing layer was 120 μm (average value of 10 sheets), and the number of cloudiness was 2 per sheet, and it was confirmed that the strengthening was performed well.
（実施例２、３及び参考例４、５）
化学強化処理液における硝酸ナトリウム（ＮａＮＯ３）と硝酸カリウム（ＫＮＯ３）の混合比を変えた以外は実施例１と同じ条件で化学強化処理を行い、強化層の厚みと膜の白濁の評価を行った。
(Examples 2 and 3 and Reference Examples 4 and 5)
Except for changing the mixing ratio of sodium nitrate (NaNO 3 ) and potassium nitrate (KNO 3 ) in the chemical strengthening treatment solution, the chemical strengthening treatment was performed under the same conditions as in Example 1 to evaluate the thickness of the strengthening layer and the cloudiness of the film. It was.
混合比は、硝酸カリウム１００質量部に対して、硝酸ナトリウム１質量部（実施例２）、５質量部（実施例３）、２５質量部（参考例４）、５０質量部（参考例５）とした。このときのナトリウムイオン／カリウムイオンのモル比は、それぞれ、約０．０１（実施例２）、約０．０６（実施例３）、約０．３（参考例４）、約０．５９（参考例５）となる。 The mixing ratio is 1 part by mass of sodium nitrate (Example 2), 5 parts by mass (Example 3), 25 parts by mass ( Reference Example 4), 50 parts by mass ( Reference Example 5) and 100 parts by mass of potassium nitrate. did. The molar ratio of sodium ion / potassium ion at this time is about 0.01 (Example 2), about 0.06 (Example 3), about 0.3 ( Reference Example 4), and about 0.59 (respectively). Reference example 5) is obtained.
評価結果を表１に併せて示す。強化層の厚み、白濁の数とも問題なく、良好に強化が行われたことが確認された。 The evaluation results are also shown in Table 1. It was confirmed that the strengthening was carried out satisfactorily without any problem in the thickness of the reinforcing layer and the number of cloudiness.
（比較例１〜４）
化学強化処理液における硝酸ナトリウム（ＮａＮＯ3）と硝酸カリウム（ＫＮＯ3）の混合比を変えた以外は実施例１と同じ条件で化学強化処理を行い、強化層の厚みと膜の白濁の評価を行った。
(Comparative Examples 1-4)
Except for changing the mixing ratio of sodium nitrate (NaNO 3 ) and potassium nitrate (KNO 3 ) in the chemical strengthening treatment liquid, the chemical strengthening treatment was performed under the same conditions as in Example 1 to evaluate the thickness of the strengthening layer and the cloudiness of the film. It was.
比較例１では化学強化処理液として硝酸カリウムのみからなる溶融塩を用い、硝酸ナトリウムは混合しなかった。また、比較例２〜４における化学強化処理液の混合比は、硝酸カリウム１００質量部に対して、硝酸ナトリウム０．７質量部（比較例２）、６０質量部（比較例３）、１００質量部（比較例４）とした。このときのナトリウムイオン／カリウムイオンのモル比は、それぞれ、約０．００８（比較例２）、約０．７１（比較例３）、約１．１９（比較例４）となる。 In the comparative example 1, the molten salt which consists only of potassium nitrate was used as a chemical strengthening process liquid, and sodium nitrate was not mixed. Moreover, the mixing ratio of the chemical strengthening process liquid in Comparative Examples 2-4 is 0.7 mass part of sodium nitrate (comparative example 2), 60 mass parts (comparative example 3), and 100 mass parts with respect to 100 mass parts of potassium nitrate. (Comparative Example 4). The molar ratio of sodium ion / potassium ion at this time is about 0.008 (Comparative Example 2), about 0.71 (Comparative Example 3), and about 1.19 (Comparative Example 4), respectively.
評価結果を表１に併せて示す。比較例１、２では強化層の厚みが１００μｍに満たずイオン交換がスムーズに進行していないことが確認された。また、比較例３、４ではディスク１枚当たりの白濁の数が１０個以上であり問題となることが確認された。 The evaluation results are also shown in Table 1. In Comparative Examples 1 and 2, it was confirmed that the thickness of the reinforcing layer was less than 100 μm and ion exchange did not proceed smoothly. In Comparative Examples 3 and 4, it was confirmed that the number of cloudiness per disc was 10 or more, which was a problem.
Claims (2)
前記ガラス基板は、リチウムイオンを成分として含有するガラス基板であり、
前記化学強化処理液は、ナトリウムイオン及びカリウムイオンを含む溶融塩であって、前記化学強化処理液に含まれるナトリウムイオン／カリウムイオンのモル比が０．０１〜０．１２であり、
前記化学強化する工程は、該化学強化処理液のみを用いて行われることを特徴とする情報記録媒体用ガラス基板の製造方法。 In the method for producing a glass substrate for an information recording medium, comprising immersing the glass substrate in a chemical strengthening treatment liquid, and ion-exchanging ions on the surface of the glass substrate with ions in the chemical strengthening treatment liquid to chemically strengthen the glass substrate.
The glass substrate is a glass substrate containing lithium ions as a component,
The chemical strengthening treatment liquid is a molten salt containing sodium ions and potassium ions, the molar ratio of sodium ions / potassium ions contained in the chemical strengthening treatment liquid Ri der 0.01 to 0.12,
The method for producing a glass substrate for an information recording medium, wherein the chemical strengthening step is performed using only the chemical strengthening treatment liquid .
その混合比が、硝酸カリウム１００質量部に対して、硝酸ナトリウム１質量部〜１０質量部であることを特徴とする請求項１に記載の情報記録媒体用ガラス基板の製造方法。 The chemical strengthening treatment liquid is a mixed molten salt composed of potassium nitrate and sodium nitrate,
The method for producing a glass substrate for an information recording medium according to claim 1, wherein the mixing ratio is 1 to 10 parts by mass of sodium nitrate with respect to 100 parts by mass of potassium nitrate .
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