# US 2010/0167091 A1 · Glass for use in substrate for information recording medium, substrate for information recording medium and information recording medium, and their manufacturing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0167091 A1 - Document ID: US20100167091A1 - Status: Published application - Kind: A1 - Application number: 12/303,795 - Filed: 2007-06-08 - Published: 2010-07-01 - Earliest claimed: 2006-06-08 - Assignees: Hoya Corporation - Inventors: Kazuo Tachiwana; Yoichi Hachitani; Xuelu Zou; Mikio Ikenishi; Kinobu Osakabe - Web page: https://patentgrep.com/patent/US20100167091A1 ## CPC - G11B 5/739: {Magnetic recording media substrates} - C03C 3/083: containing aluminium oxide or an iron compound - C03C 3/087: containing calcium oxide, e.g. common sheet or container glass - C03C 3/095: containing rare earths - C03C 3/097: containing phosphorus, niobium or tantalum - 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) - 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) - C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)} - C03C 23/0075: {Cleaning of glass (specially adapted to plate glass B08B11/00)} - G11B 5/7315 - G11B 5/82: Disk carriers - G11B 5/8404: {manufacturing base layers} - Y10T 428/24273: including aperture - Y10T 428/315: Surface modified glass [e.g., tempered, strengthened, etc.] - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## 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 ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 1) The glass according to claim 1, which comprises, denoted as molar percentages, 50 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. ### Claim 5 Glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, 50 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. ### Claim 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. ### Claim 7 (depends on 6) 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. ### Claim 8 (depends on 6) 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. ### Claim 9 (depends on 6) The glass according to claim 6, wherein the total content of Li2O and Na2O is equal to or less than 22 molar percent. ### Claim 10 (depends on 6) The glass according to claim 6, which comprises, denoted as molar percentages, 60 to 75 percent of SiO2; 3 to 15 percent of Al2O3; and 0.3 to 4 percent of ZrO2. ### Claim 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. ### Claim 12 (depends on 11) 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. ### Claim 13 (depends on 11) The glass according to claim 11, wherein the total content of SiO2 and Al2O3 is equal to or greater than 75 molar percent. ### Claim 14 (depends on 11) 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. ### Claim 15 (depends on 11) 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. ### Claim 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. ### Claim 17 (depends on 16) 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. ### Claim 18 (depends on 16) The glass according to claim 16, wherein the total content of SiO2 and Al2O3 is equal to or greater than 75 molar percent. ### Claim 19 (depends on 16) 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. ### Claim 20 (depends on 16) 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. ### Claim 21 (depends on 16) The glass according to claim 16, wherein the total content of Li2O and Na2O is equal to or less than 22 molar percent. ### Claim 22 (depends on 16) The glass according to claim 16, which comprises, denoted as molar percentages, 60 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. ### Claim 23 Glass for use in substrate for information recording medium, which comprises, denoted as mass percentages, 57 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. ### Claim 24 Glass for use in substrate for information recording medium, which comprises, denoted as mass percentages, 57 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. ### Claim 25 (depends on 23) The glass according to claim 23, wherein the total content of SiO2 and Al2O3 is greater than 79 percent. ### Claim 26 (depends on 23) The glass according to claim 23, which comprises equal to or greater than 11 percent of Al2O3. ### Claim 27 (depends on 23) The glass according to claim 23, which comprises 0.1 to 4 percent of MgO. ### Claim 28 (depends on 23) 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. ### Claim 29 (depends on 1) The glass according to claim 1, which further comprises Fe. ### Claim 30 (depends on 1) Chemically strengthened glass for use in substrate for information recording medium, obtained by subjecting the glass according to claim 1 to chemical strengthening treatment. ### Claim 31 (depends on 1) A glass substrate for information recording medium being comprised of the glass according to claim 1. ### Claim 32 (depends on 31) 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. ### Claim 33 (depends on 31) The glass substrate for information recording medium according to claim 31, which has been subjected to chemical strengthening treatment. ### Claim 34 (depends on 31) The glass substrate for information recording medium according to claim 31, which has a deflecting strength of equal to or greater than 10 kg. ### Claim 35 (depends on 31) The glass substrate for information recording medium according to claim 31, which has a thickness of equal to or less than 1 mm. ### Claim 36 (depends on 31) The glass substrate for information recording medium according to claim 31, which has a thickness of equal to or greater than 0.3 mm. ### Claim 37 (depends on 31) The glass substrate for information recording medium according to claim 31, which is disk-shaped. ### Claim 38 (depends on 37) The glass substrate for information recording medium according to claim 37, which has a hole in the center. ### Claim 39 (depends on 1) 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. ### Claim 40 (depends on 39) 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. ### Claim 41 (depends on 39) 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. ### Claim 42 (depends on 39) 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. ### Claim 43 (depends on 31) An information recording medium comprising an information recording layer on the glass substrate for information recording medium according to claim 31. ### Claim 44 (depends on 43) The information recording medium according to claim 43, which is a perpendicular magnetic recording-mode magnetic recording medium. ### Claim 45 (depends on 44) 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. ### Claim 46 (depends on 43) The magnetic recording medium according to claim 43, which has a recording density of equal to or greater than 130 Gbit/inch2. ### Claim 47 (depends on 39) 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.