Glass substrate for information recording medium and magnetic information recording medium to which the glass substrate is applied
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
C03C-003/085
C03C-003/091
G11B-007/241
출원번호
US-0656512
(2010-02-01)
등록번호
US-8222170
(2012-07-17)
우선권정보
JP-2001-165226 (2001-05-31)
발명자
/ 주소
Ikenishi, Mikio
Morita, Atsuko
Zou, Xuelu
출원인 / 주소
Hoya Corporation
대리인 / 주소
Nixon & Vanderhye P.C.
인용정보
피인용 횟수 :
4인용 특허 :
28
초록▼
Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 μm−1/2 or less or having a fragility index value, measured in a
Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 μm−1/2 or less or having a fragility index value, measured in an atmosphere having a dew point of −5° C. or lower, of 7 μm−1/2 or less, or the glass substrate comprising, by mol %, 40 to 75% of SiO2, 2 to 45% of B2O3 and/or Al2O3 and 0 to 40% of R′2O in which R′ is at least one member selected from the group consisting of Li, Na and K), wherein the total content of SiO2, B2O3, Al2O3 and R′2O is at least 90 mol %, and a magnetic information recording medium comprising a magnetic recording layer formed on the glass substrate.
대표청구항▼
1. A magnetic information recording medium comprising a magnetic recording layer formed on a glass substrate for an information recording medium, said glass substrate comprising, by mol %, 40 to 74.5% of SiO2, 7.5 to 15% of Al2O3, 1% or more MgO as RO, 0 to 25% of B2O3, the total content of Al2O3 an
1. A magnetic information recording medium comprising a magnetic recording layer formed on a glass substrate for an information recording medium, said glass substrate comprising, by mol %, 40 to 74.5% of SiO2, 7.5 to 15% of Al2O3, 1% or more MgO as RO, 0 to 25% of B2O3, the total content of Al2O3 and B2O3 being 7.5% or more, 1 to 12% of total RO in which R is at least one member selected from the group consisting of Mg, Ca, Zn, Sr and Ba, wherein MgO is an essential component and CaO, ZnO, SrO and BaO are optional components, 17 to 25% of total R′2O in which R′ is Li, Na and K, 0 to 7% of TiO2 and 0 to 7% of ZrO2, the glass substrate containing 10 to 18% of Li2O, 1 to 10% of Na2O and 2 to 8% of K2O as R′2O, the total content of SiO2, Al2O3, B2O3, RO and R′2O being 90% or more, the total content of RO and R′2O being 18 to 29%. 2. The magnetic information recording medium of claim 1, wherein the glass substrate has a fragility index value, measured in an atmosphere having a dew point of −5° C. or lower, of 7 μm−1/2 or less. 3. The magnetic information recording medium of claim 1, wherein the glass substrate has a Young's modulus of at least 70 GPa. 4. The magnetic information recording medium of claim 1, wherein the glass substrate has a modulus of rigidity of at least 20 GPa. 5. The magnetic information recording medium of claim 1, wherein the glass substrate is made of a glass having a region wherein the glass has a viscosity of at least 1 Pa·s, in a range of temperatures equivalent to, and higher than, a liquidus temperature of the glass. 6. The magnetic information recording medium of claim 1, wherein the glass substrate is made of a glass having a thermal expansion coefficient of 60×10−7/° C. or greater at a temperature of 100° C. to 300° C. 7. The magnetic information recording medium of claim 1, wherein the glass substrate has no chemically strengthened layer. 8. The magnetic information recording medium of claim 1, wherein the glass substrate has a chemically strengthened layer. 9. The magnetic information recording medium of claim 1, wherein said glass substrate contains 5 mol % or more of RO. 10. The magnetic information recording medium of claim 9, wherein said glass substrate contains 1 to 5 mol % of Na2O. 11. The magnetic information recording medium of claim 10, wherein said glass substrate contains 60 to 74.5 mol % of SiO2.
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