GLASS FOR USE IN SUBSTRATE FOR INFORMATION RECORDING MEDIUM, SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND INFORMATION RECORDING MEDIUM, AND THEIR MANUFACTURING METHOD

• US 20100167091A1
• Filed: 06/08/2007
• Published: 07/01/2010
• Est. Priority Date: 06/08/2006
• Status: Active Grant

• Current Assignee: Hoya Corporation
• Original Assignee: Hoya Corporation
• Inventors: Ikenishi, Mikio, Tachiwana, Kazuo, Zou, Xuelu, Hachitani, Yoichi, Osakabe, Kinobu
• Granted Patent: US 8,076,014 B2
• Time in Patent Office: Days
• US Class Current: 428/828
• CPC Class Codes: C03C 15/00 Surface treatment of glass, not in the form of fibres or filaments, by etching etching or surface-brightening compositions, in general C09K13/00
• CPC Class Codes: C03C 19/00 Surface treatment of glass, not in the form of fibres or filaments, by mechanical means sand-blasting, grinding, or polishing glass B24
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 23/0075 Cleaning of glass specially adapted to plate glass B08B11/00
• CPC Class Codes: C03C 3/083 containing aluminium oxide or an iron compound
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: C03C 3/095 containing rare earths
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: G11B 5/7315 substrates
• CPC Class Codes: G11B 5/739 Magnetic recording media substrates
• CPC Class Codes: G11B 5/82 Disk carriers
• CPC Class Codes: G11B 5/8404 manufacturing base layers
• CPC Class Codes: Y10T 428/24273 including aperture
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO₂ and Al₂O₃, where SiO₂ content is equal to or greater than 50 percent and Al₂O₃ content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li₂O, Na₂O and K₂O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂; with the molar ratio of the total content of Li₂O, Na₂O and K₂O to the total content of SiO₂, Al₂O₃, ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂ ((Li₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃+ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+Y₂O₃+TiO₂)) being equal to or less than 0.28. Further provided are the substrate for information recording medium, information recording medium and their manufacturing methods according to the present invention.

Claims

1. Glass for use in substrate for information recording medium, which comprises, denoted as molar percentages,

a total of 70 to 85 percent of SiO₂ and Al₂O₃, where SiO₂ content is equal to or greater than 50 percent and Al₂O₃ content is equal to or greater than 3 percent;

a total of equal to or greater than 10 percent of Li₂O, Na₂O and K₂O;

a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content;

a total of greater than 0 percent but equal to or lower than 4 percent of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃ Y₂O₃ and TiO₂;

with the molar ratio of the total content of Li₂O, Na₂O and K₂O to the total content of SiO₂, Al₂O₃, ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂ ((Li₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃+ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+Y₂O₃+TiO₂)) being equal to or less than 0.28.

2. The glass according to claim 1, wherein SiO₂ content is equal to or greater than 60 molar percent, and the total content of SiO₂ and Al₂O₃ is equal to or greater than 75 molar percent.

3. The glass according to claim 1, wherein, denoted as molar percentages, the total content of CaO and MgO is greater than the total content of SrO and BaO, and the molar ratio of the total content of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂ to the total content of Li₂O, Na₂O, K₂O, MgO, CaO, SrO and BaO ((ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+Y₂O₃+TiO₂)/(Li₂O+Na₂O+K₂O+MgO+CaO+SrO+BaO)) is equal to or greater than 0.035.

4. The glass according to claim 1, which comprises, denoted as molar percentages,to 75 percent of SiO₂;

3 to 15 percent of Al₂O₃;

5 to 15 percent of Li₂O;

5 to 15 percent of Na₂O;

0 to 3 percent of K₂O;

greater than 0.5 percent but equal to or less than 5 percent of CaO;

equal to or greater than 0 percent but less than 3 percent of MgO; and

0.3 to 4 percent of ZrO₂.

29. The glass according to claim 1, which further comprises Fe.

30. Chemically strengthened glass for use in substrate for information recording medium, obtained by subjecting the glass according to claim 1 to chemical strengthening treatment.

31. A glass substrate for information recording medium being comprised of the glass according to claim 1.

32. The glass substrate for information recording medium according to claim 31, which has a main surface with a roughness Ra of less than 0.25 nm.

33. The glass substrate for information recording medium according to claim 31, which has been subjected to chemical strengthening treatment.

34. The glass substrate for information recording medium according to claim 31, which has a deflecting strength of equal to or greater than 10 kg.

35. The glass substrate for information recording medium according to claim 31, which has a thickness of equal to or less than 1 mm.

36. The glass substrate for information recording medium according to claim 31, which has a thickness of equal to or greater than 0.3 mm.

37. The glass substrate for information recording medium according to claim 31, which is disk-shaped.

38. The glass substrate for information recording medium according to claim 37, which has a hole in the center.

39. A method of manufacturing a glass substrate for information recording medium, which comprises the steps of mirror finishing the glass according to claim 1, and following mirror polishing, conducting acid cleaning and alkali cleaning.

40. The method of manufacturing a glass substrate for information recording medium according to claim 39, which further comprises chemical strengthening treatment between said mirror finishing step and cleaning step.

41. The method of manufacturing a glass substrate for information recording medium according to claim 39, wherein the acid cleaning and the alkali cleaning are sequentially conducted.

42. The method of manufacturing a glass substrate for information recording medium according to claim 39, wherein the alkali cleaning is conducted following the acid cleaning.

43. An information recording medium comprising an information recording layer on the glass substrate for information recording medium according to claim 31.

44. The information recording medium according to claim 43, which is a perpendicular magnetic recording-mode magnetic recording medium.

45. The information recording medium according to claim 44, which has a soft magnetic underlayer, an amorphous underlayer, a crystalline underlayer, a perpendicular magnetic recording layer, a protective layer and a lubricating layer in this order on said substrate.

46. The magnetic recording medium according to claim 43, which has a recording density of equal to or greater than 130 Gbit/inch².

47. A method of manufacturing an information recording medium, wherein a glass substrate for information recording medium is manufactured by the method according to claim 39, and an information recording layer is formed on said glass substrate.

5. Glass for use in substrate for information recording medium, which comprises, denoted as molar percentages,to 75 percent of SiO₂;

3 to 15 percent of Al₂O₃;

5 to 15 percent of Li₂O;

5 to 15 percent of Na₂O;

0 to 3 percent of K₂O;

greater than 0.5 percent but equal to or less than 5 percent of CaO;

equal to or greater than 0 percent but less than 3 percent of MgO, with CaO content being greater than MgO content; and

0.3 to 4 percent of ZrO₂;

with the molar ratio of the total content of Li₂O, Na₂O and K₂O to the total content of SiO₂, Al₂O₃ and ZrO₂ ((Li₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃+ZrO₂)) being equal to or less than 0.28.

6. Glass for use in substrate for information recording medium, which comprises SiO₂;

Al₂O₃;

one or more alkali metal oxides selected from the group consisting of Li₂O, Na₂O and K₂O;

one or more alkaline earth metal oxides selected from the group consisting of MgO, CaO, SrO and BaO; and

one or more oxides selected from the group consisting of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂;

wherein SiO₂ content is equal to or greater than 50 molar percent, and the total content of SiO₂ and Al₂O₃ is equal to or greater than 70 molar percent;

the total content of said alkali metal oxides and said alkaline earth meal oxides is equal to or greater than 8 molar percent; and

the molar ratio of the total content of said oxides to the total content of said alkali metal oxides and said alkaline earth metal oxides ((ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+TiO₂)/(Li₂O+Na₂O+K₂O+MgO+CaO+SrO+BaO)) is equal to or greater than 0.035.

7. The glass according to claim 6, wherein SiO₂ content is equal to or greater than 60 molar percent, and the total content of SiO₂ and Al₂O₃ is equal to or greater than 75 molar percent.

8. The glass according to claim 6, which comprises at least one of Li₂O and Na₂O, and wherein the total content of Li₂O and Na₂O is less than 24 molar percent.

9. The glass according to claim 6, wherein the total content of Li₂O and Na₂O is equal to or less than 22 molar percent.

10. The glass according to claim 6, which comprises, denoted as molar percentages,to 75 percent of SiO₂;

3 to 15 percent of Al₂O₃; and

0.3 to 4 percent of ZrO₂.

11. Aluminosilicate glass for chemical strengthening for use in substrate for information recording medium, which comprises:

one or more alkali metal oxides selected from the group consisting of Li₂O, Na₂O and K₂O, one or more alkaline earth metal oxides selected from the group consisting of MgO, CaO, SrO and BaO, and one or more oxides selected from the group consisting of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂;

wherein the total content of Li₂O and Na₂O is 10 to 22 molar percent;

the total content of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂ is greater than 0 molar percent but equal to or less than 4 molar percent; and

the molar ratio of the total content of said oxides to the total content of said alkaline earth metal oxides ((ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+Y₂O₃+TiO₂)/(MgO+CaO+SrO+BaO)) is equal to or greater than 0.15.

12. The glass according to claim 11, wherein SiO₂ content is equal to or greater than 50 molar percent, and the total content of SiO₂ and Al₂O₃ is equal to or greater than 70 molar percent.

13. The glass according to claim 11, wherein the total content of SiO₂ and Al₂O₃ is equal to or greater than 75 molar percent.

14. The glass according to claim 11, wherein the molar ratio of the total content of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂ to the total content of Li₂O, Na₂O, K₂O, MgO, CaO, SrO and BaO ((ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+Y₂O₃+TiO₂)/(Li₂O+Na₂O+K₂O+MgO+CaO+SrO+BaO)) is equal to or greater than 0.035.

15. The glass according to claim 11, which comprises, denoted as molar percentages,

equal to or greater than 3 percent of Al₂O₃;

a total of equal to or greater than 8 percent of Li₂O, Na₂O, K₂O, MgO, CaO, SrO and BaO; and

a total of greater than 0 percent but equal to or less than 5 percent of MgO, CaO, SrO and BaO.

16. Glass for use in substrate for information recording medium, which comprises SiO₂;

Al₂O₃;

one or more alkali metal oxides selected from the group consisting of Li₂O, Na₂O and K₂O;

one or more alkaline earth metal oxides selected from the group consisting of MgO, CaO, SrO and BaO; and

one or more oxides selected from the group consisting of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂;

which has an acidity resistance resulting in an etching rate of equal to or less than 3.0 nm/minute when immersed in 0.5 volume percent hydrogenfluosilicic acid (H₂SiF) aqueous solution maintained at 50°

C.; and

which has an alkalinity resistance resulting in an etching rate of equal to or less than 0.1 nm/minute when immersed in 1 mass percent potassium hydroxide aqueous solution maintained at 50°

C.

17. The glass according to claim 16, wherein SiO₂ content is equal to or greater than 50 molar percent, and the total content of SiO₂ and Al₂O₃ is equal to or greater than 70 molar percent.

18. The glass according to claim 16, wherein the total content of SiO₂ and Al₂O₃ is equal to or greater than 75 molar percent.

19. The glass according to claim 16, which has a composition that the total content of said alkali metal oxides and said alkaline earth metal oxides is equal to or greater than 8 molar percent, and the molar ratio of the total content of said oxides to the total content of said alkali metal oxides and said alkaline earth metal oxides ((ZrO₂+HfO₂+Nb₂O₅+Ta₂O₅+La₂O₃+Y₂O₃+TiO₂)/(Li₂O+Na₂O+K₂O+MgO+CaO+SrO+BaO)) is equal to or greater than 0.035.

20. The glass according to claim 16, which comprises at least one of Li₂O and Na₂O, and wherein the total content of Li₂O and Na₂O is equal to or less than 24 molar percent.

21. The glass according to claim 16, wherein the total content of Li₂O and Na₂O is equal to or less than 22 molar percent.

22. The glass according to claim 16, which comprises, denoted as molar percentages,to 75 percent of SiO₂;

3 to 15 percent of Al₂O₃; and

a total of 0.3 to 4 percent of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂.

23. Glass for use in substrate for information recording medium, which comprises, denoted as mass percentages,to 75 percent of SiO₂;

5 to 20 percent of Al₂O₃, with the total content of SiO₂ and Al₂O₃ being equal to or greater than 74 percent;

a total of greater than 0 percent but equal to or less than 6 percent of ZrO₂, HfO₂, Nb₂O₅, Ta₂O₅, La₂O₃, Y₂O₃ and TiO₂;

greater than 1 percent but equal to or less than 9 percent of Li₂O;

5 to 18 percent of Na₂O, with the mass ratio, Li₂O/Na₂O being equal to or less than 0.5;

0 to 6 percent of K₂O;

0 to 4 percent of MgO;

greater than 0 percent but equal to or less than 5 percent of CaO, with the total content of MgO and CaO being equal to or less than 5 percent and CaO content being greater than MgO content; and

a total of 0 to 3 percent of SrO and BaO.

25. The glass according to claim 23, wherein the total content of SiO₂ and Al₂O₃ is greater than 79 percent.

26. The glass according to claim 23, which comprises equal to or greater than 11 percent of Al₂O₃.

27. The glass according to claim 23, which comprises 0.1 to 4 percent of MgO.

28. The glass for use in substrate for information recording medium according to claim 23, wherein the total content of SiO₂, Al₂O₃, ZrO₂, Li₂O, Na₂O, K₂O, MgO and CaO is equal to or greater than 99 percent.

24. Glass for use in substrate for information recording medium, which comprises, denoted as mass percentages,to 75 percent of SiO₂;

5 to 20 percent of Al₂O₃, with the total content of SiO₂ and Al₂O₃ being equal to or greater than 74 percent;

greater than 0 percent but equal to or less than 5.5 percent of ZrO₂;

greater than 1 percent but equal to or less than 9 percent of Li₂O;

5 to 18 percent of Na₂O, with the mass ratio, Li₂O/Na₂O being equal to or less than 0.5;

0 to 6 percent of K₂O;

0 to 4 percent of MgO;

greater than 0 percent but equal to or less than 5 percent of CaO, with the total content of MgO and CaO being equal to or less than 5 percent and CaO content being greater than MgO content;

a total of 0 to 3 percent of SrO and BaO; and

0 to 1 percent of TiO₂.