Abstract: To provide glass for a data storage medium substrate, whereby high heat resistance can be obtained. Glass for a data storage medium substrate, which comprises, as represented by mol percentage based on the following oxides, from 55 to 70% of SiO2, from 2.5 to 9% of Al2O3, from 0 to 10% of MgO, from 0 to 7% of CaO, from 0.5 to 10% of SrO, from 0 to 12.5% of BaO, from 0 to 2.5% of TiO2, from 0.5 to 3.7% of ZrO2, from 0 to 2.5% of Li2O, from 0 to 8% of Na2O, from 2 to 8% of K2O and from 0.5 to 5% of La2O3, provided that the total content of Al2O3 and ZrO2 (Al2O3+ZrO2) is at most 12%, and the total content of Li2O, Na2O and K2O (R2O) is at most 12%.

Abstract: The present invention is directed to the fabrication of rigid memory disks, including a metal plating composition which impedes deposition of non-metallic particles during a plating process. The plating composition includes at least one sulfated fatty acid ester additive, or mixtures or salts thereof, of formula: wherein R1 is selected from the group consisting of OH, OCH2, H2CH3, C1-C7 alkyl, linear or branched; R2 selected from H and C1-C7 alkyl, linear or branched; m=1 to about 5; n=2 to about 30; o=0 to about 10; M+ is a metal or pseudo metal ion or H+. The additive has a zeta potential which impedes deposit of non-metallic particles. The invention is further directed to a method for electroless plating utilizing the additive composition in a bath with at least a stabilizing agent, complexing agent and reducing agent and source of metal ions.

Abstract: A patterned perpendicular magnetic recording disk with discrete data islands of recording layer (RL) material includes a substrate, a patterned exchange bridge layer of magnetic material between the substrate and the islands, and an optional exchange-coupling control layer (CCL) between the exchange bridge layer and the islands. The exchange bridge layer has patterned pedestals below the islands. The exchange bridge layer controls exchange interactions between the RLs in adjacent islands to compensate the dipolar fields between islands, and the pedestals concentrate the flux from the write head. The disk may include a soft underlayer (SUL) of soft magnetically permeable material on the substrate and a nonmagnetic exchange break layer (EBL) on the SUL between the SUL and the exchange bridge layer. In a thermally-assisted recording (TAR) disk a heat sink layer may be located below the exchange bridge layer and the SUL may be optional.

Abstract: A glass substrate for information recording medium, said glass substrate being composed of an aluminosilicate glass containing 60-75% by mass of SiO2, 5-18% by mass of Al2O3, 3-10% by mass of Li2O, 3-15% by mass of Na2O and 0.5-8% by mass of ZrO2 relative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one polyvalent element selected from the group consisting of V (vanadium), Mn (manganese), Ni (nickel), Nb (niobium), Mo (molybdenum), Sn (tin), Ce (cerium), Ta (tantalum) and Bi (bismuth). The molar ratio of the total amount of the polyvalent elements to the amount of Al2O3 is within the range of 0.02-0.20.

Abstract: A hard drive platter comprises a substrate that includes glassy metal. At least one magnetic layer is arranged on the substrate. The glassy metal includes at least three of zirconium, titanium, nickel, copper, and/or beryllium. A perpendicular recording system comprises the hard drive platter. A hard disk drive comprises the hard drive platter. A computer comprises the hard disk drive. A digital camera comprises the hard drive platter. A portable media player comprises the hard drive platter. An insulating layer and/or an Aluminum layer may be located between the glassy metal substrate and the at least one magnetic layer.

Abstract: Disclosed are a biaxially oriented polyester film which is excellent in dimensional stability, especially dimensional stability against environmental changes in, for example, temperature and humidity, and a polyester capable of providing the biaxially oriented polyester film with excellent dimensional stability. There is provided a copolymerized aromatic polyester containing aromatic dicarboxylic acid components represented by the following formulae (I) and (II) and a glycol component represented by the following formula (III), wherein a 4,4?-(alkylenedioxy)bisbenzoic acid component represented by the formula (I) is contained in an amount of 5% by mole or more and less than 90% by mole on the basis of a molar number of an aromatic dicarboxylic acid component; and a film thereof.

Abstract: A biaxially oriented polyester film which has a Young's modulus (YMD) in the film machine direction (YMD) of 6.5 GPa or more and a Young's modulus in the width direction (YTD) of 8.2 to 9.8 GPa and is used as a base film for magnetic recording tapes of linear recording system, and a magnetic recording tape of linear recording system comprising the same as a base film. There are provided a biaxially oriented polyester film which has excellent dimensional stability, especially dimensional stability in the width direction and is suitable for use as a base film for magnetic recording tapes of linear recording system and a magnetic recording tape comprising the same.

Abstract: To provide a process to improve acid resistance of a glass substrate for an information recording medium. A process for producing a glass substrate for an information recording medium, comprising processing a glass formed into a plate by a float process, a down-draw method or a press method, wherein, in cooling of the glass in the last step where the glass has a temperature of at least its strain point, the time during which the glass temperature is at least its strain point and at most a temperature where the glass viscosity is 1010 dPa·s is at least 13 minutes.

Abstract: A disk for a hard disk drive is provided. The disk comprises a substrate comprising aluminum, and a coating layer disposed over the substrate. The coating layer comprises an alloy of Ni, X1 and X2, wherein X1 comprises one or more elements selected from the group consisting of Ag, Au, B, Cr, Cu, Ga, In, Mn, Mo, Nb, Pb, Sb, Se, Sn, Te, W, Zn and Zr, and wherein X2 comprises either B or P, and wherein X1 and X2 do not comprise the same elements.

Abstract: There is provided a glass substrate which has the properties required in the use as a substrate for an information recording medium of the next generation such as a perpendicular magnetic recording system, and can be applied as a substrate for an information recording medium of the next generation particularly on the premise of using the glass substrate in a dynamic environment. More particularly, there is provided a glass substrate for an information recording medium which has sufficiently high surface hardness, has a good balance between specific gravity and mechanical strength, and has high strength to withstand high speed rotation or drop impact, and which can be produced with a high productivity adequate for a direct press method, without the occurrence of bubbles in the glass blank or reboil upon pressing even if arsenic components or antimony components are not substantially used.

Abstract: The present invention relates to recording glass substrates molar percentages: 56-75 SiO2, 1-11 Al2O2, more than 0-4 Li2O, 1-15 Na2O. more than 0 less than 3 K2O, no BaO. total Li2O, Na2O and K2O 6-15, (Li2O Na2O) less than 0.50, {K2O/(Li2O, Na2O and K2O)} equal or less than 0.13, total MgO, CaO and SrO 10-30, MgO and CaO 10-30, {(MgO+CaO)/(MgO+CaO+SrO)} equal or more than 0.86, alkali oxides to alkaline earth oxides equal to or more than 0.50. total ZrO2, TiO2, Y2O3, La2O3, Gd2O3, Nb2O5, and Ta2O5 more than 0 equal to or less than 10, molar ratio {(ZrO2, TiO2, Y2O3, La2O3, Gd2O3, Nb2O5, and Ta2O5)/Al2O2 equal or more than 0.40, Tg equal to or higher than 600° C., average coefficient linear expansion equal or higher than 70×10?7/°C. at 100-300° C. and Young's modulus equal to or higher than 80 GPa.

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, La2O3Y2O3 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.

Abstract: A magnetic tape produced by cutting a magnetic sheet with a wide breadth into a tape having a predetermined width using a cutting device, in which the magnetic sheet has a magnetic layer containing magnetic powder and a binder formed on one surface of a non-magnetic substrate having a thickness of 4 ?m or less, and a center line average height (Ra) along a roughness curve of a cut edge of the magnetic tape is from 0.08 to 0.25 ?m.

Abstract: To provide a process to improve acid resistance of a glass substrate for an information recording medium. A process for producing the glass substrate for an information recording medium, includes processing a glass formed into a plate by a float process, a down-draw method or a press method, wherein, in cooling the glass at the last step the glass has a temperature of at least its strain point, the time during which the glass temperature is at least its strain point and at most a temperature where the glass viscosity is 1010dPa·s is at least 13 minutes.

Abstract: Embodiments of the invention reduce generation of a magnetic field with a polarity reverse to that of the recording magnetic field, without deteriorating a gradient in the magnetic field. An embodiment of a magnetic disk device according to the present invention suppresses deviation and erase of already recorded data. In an embodiment, the perpendicular magnetic recording head includes the main magnetic pole, an auxiliary magnetic pole, a trailing shield disposed on the trailing side of the main magnetic pole with a non-magnetic film placed in-between, and side shields disposed on both the sides of the main magnetic pole in the direction of the track width with a non-magnetic film placed in-between. The trailing shield has on the trailing side a portion where film thickness is thinner on the trailing side than the thickness of its element in the height direction in its position facing the main magnetic pole.

Abstract: The present invention relates to a method for manufacturing a glass substrate for information recording medium, the method including: a lapping step of lapping a circular glass plate made of an alkali aluminosilicate glass; and a subsequent cerium oxide polishing step of polishing the circular glass plate with a slurry containing a cerium oxide abrasive, in which a difference (SiO2?Al2O3) obtained by subtracting an Al2O3 content from an SiO2 content in the alkali aluminosilicate glass is 62% by mole or less; and in which the method further includes: subsequently to the cerium oxide polishing step, a cleaning step of cleaning the circular glass plate with a cleaning liquid having a sulfuric acid concentration of 20% by mass or more and 80% by mass or less and a hydrogen peroxide concentration of 1% by mass or more and 10% by mass or less at a liquid temperature of 50° C. or higher and 100° C.

Abstract: A biaxially oriented laminated polyester film which has dimensional stability against environmental changes such as temperature and humidity variations and rarely elongates when a load is applied thereto at a high temperature. The biaxially oriented laminated film comprises a film layer (A) made of an aromatic polyester (A) and a film layer (B) made of an aromatic polyester (B), wherein the content of a 6,6?-(alkylenedioxy)di-2-naphthoic acid component represented by the following formula (I) based on the total of all the acid components is less than 5 mol % in the aromatic polyester (A) and not less than 5 mol % and less than 80 mol % in the aromatic polyester (B); and the peak temperature of tan ? on a high temperature side is 135° C. or higher when viscoelasticity is measured in the machine direction. (in the formula (I), R is an alkylene group having 1 to 10 carbon atoms.

Abstract: To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl2O4 and R2TiO4 as a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Abstract: A glass substrate for a magnetic disk, wherein, in regions with respect to two places arbitrarily selected on a surface of the glass substrate on its central portion side relative to its outer peripheral end, a surface shape with a shape wavelength in a band of 60 to 500 ?m is extracted from surface shapes in each of the regions and, assuming that a root mean square roughness Rq of the surface shape is given as a microwaviness Rq, the difference between the microwavinesses Rq of the regions is 0.02 nm or less or the difference between standard deviations of the microwavinesses Rq of the regions is 0.04 nm or less.

Abstract: It is an object to provide a magnetic disk substrate highly reliable to prevent the occurrence of crash failure even if a magnetic disk is rotated at high speed, and suitable for a hard disk that starts and stops by the load/unload method, and a magnetic disk using such a substrate. The representative structure of a magnetic disk substrate according to this invention is a disk-shaped glass substrate 10 having a generally flat main surface 11, an end face 12, a chamfered face 13 formed between the main surface 11 and the end face 12, and an offset portion, at the periphery of the main surface 11, raised or lowered with respect to a flat surface, other than the periphery, of the main surface 11, and characterized in that the magnitude of the offset portion is approximately uniform over the entire circumference of the glass substrate 10.