Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • 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
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • 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
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
  • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • 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
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
  • C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
  • G11B5/739—Magnetic recording media substrates
  • G11B5/73911—Inorganic substrates
  • G11B5/73921—Glass or ceramic substrates
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
  • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers

Definitions

• the present invention relates to a method for manufacturing a magnetic disk and a glass substrate for an information recording medium, and more particularly to a method for manufacturing a magnetic disk for forming a magnetic recording layer at a high temperature and a glass substrate suitable for such a manufacturing method.
• heat-assisted magnetic recording technology is attracting attention as a fusion technology of light and magnetism.
• This is a technique in which a magnetic recording layer is irradiated with a laser beam or near-field light and recorded by applying an external magnetic field in a state where the coercive force is lowered in a locally heated portion, and the recorded magnetization is read by a GMR element or the like.
• recording can be performed on a medium having a high holding force, the magnetic particles can be miniaturized while maintaining thermal stability.
• silicon substrates are generally concerned with strength compared to glass substrates. Therefore, it is preferable to use a glass substrate also in the manufacture of a magnetic disk in which the magnetic recording layer is formed at a high temperature.
• an object of the present invention is to provide a method for manufacturing such a magnetic disk and a method for manufacturing a glass substrate for an information recording medium suitable for such a manufacturing method.
• the present invention is a method of manufacturing a magnetic disk including a step of forming a magnetic recording layer on a glass substrate having a temperature of 550 ° C. or higher,
• the glass substrate is expressed in mole percentage, and SiO 2 is 60 to 75%, Al 2 O 3 is 7 to 17%, B 2 O 3 is less than 0 to less than 2%, and any one component of MgO, CaO, SrO and BaO More than 18% in total and 26% or less in total, the total content of the above 7 components is 95% or more, and any one or more of Li 2 O, Na 2 O and K 2 O is less than 1% in total Provided is a method for manufacturing a magnetic disk which contains or does not contain any of these three components.
• the glass substrate contains 10.5 to 20% in total of one or more components of MgO and CaO in terms of mole percentage.
• the present invention provides a method for producing the magnetic disk, wherein the glass substrate contains Al 2 O 3 in excess of 18% in terms of mass percentage.
• the magnetic disk having a value obtained by dividing the content (molar percentage) of SiO 2 by the total amount RO of the contents (molar percentage) of MgO, CaO, SrO and BaO is 4.3 or less.
• a manufacturing method is provided.
• the present invention provides a method for manufacturing the magnetic disk, wherein a temperature T 2 at which the viscosity of the glass substrate is 10 2 dPa ⁇ s is 1710 ° C. or lower.
• SiO 2 is 60 to 75%
• Al 2 O 3 is 7 to 17%
• B 2 O 3 is 0 to less than 2%
• one or more components of MgO, CaO, SrO and BaO are contained.
• the total content is more than 18% and 26% or less
• the total content of the above seven components is 95% or more
• any one or more of Li 2 O, Na 2 O and K 2 O is contained in less than 1% in total.
• a glass substrate for an information recording medium which does not contain any of these three components.
• the glass substrate for an information recording medium containing a total of 10.5 to 20% of any one component of MgO and CaO in terms of mole percentage.
• the glass substrate for an information recording medium containing 6% or more of MgO in terms of mole percentage.
• the glass substrate for an information recording medium wherein a value obtained by dividing the content (molar percentage) of SiO 2 by the total amount RO of the contents (molar percentage) of MgO, CaO, SrO, and BaO is 4.3 or less. provide.
• the glass substrate for an information recording medium, wherein the information recording medium is a magnetic disk.
• the inventions related to these glass substrates not only enable the substrate to be heated at a high temperature in the production of the magnetic disk for forming the magnetic recording layer, but also facilitate the production as described below. Is.
• the glass having the composition shown in Example 14 of International Publication No. 2011/136027 has a low specific elastic modulus of 31.2 MNm ⁇ kg, and fluttering phenomenon easily occurs at the time of high-speed rotation of the disk and cannot cope with a high recording density. It became clear. Furthermore, it has been clarified that the glass having the above composition has insufficient acid resistance, and a phenomenon such as surface roughness is likely to occur after a polishing process or the like, and cannot cope with a high recording density. Further, it has also been clarified that the glass having the composition has insufficient alkali resistance, and a phenomenon such as surface roughness is likely to occur after a cleaning process or the like, and cannot cope with a high recording density.
• the present inventors have found the facts as described above, have heat resistance applicable to the heat-assisted magnetic recording technology, have excellent mechanical properties, have excellent chemical durability, and have excellent solubility.
• the present invention has led to the invention of the glass substrate of the present invention for the purpose of providing a glass substrate.
• the present invention also includes a disk processing step for processing a glass plate into a glass disc, a wrapping step for wrapping the main surface of the glass disc, a main surface polishing step for polishing the main surface wrapped with the glass disc, and these A method for producing a glass substrate for an information recording medium comprising a washing step of washing a glass disc between or after these steps, wherein the glass plate is expressed in mole percentage, SiO 2 is 60 to 75%, 7 to 17% of Al 2 O 3 , 0 to less than 2% of B 2 O 3 , and any one or more of MgO, CaO, SrO and BaO in total including more than 18% and 26% or less, The total content is 95% or more, and any one or more of Li 2 O, Na 2 O and K 2 O is contained in total less than 1%, or none of these three components is contained.
• a method for producing a glass substrate for an information recording medium is provided.
• the glass disk may have a so-called donut shape having a hole in the center or may have no hole. Further, the end face is usually subjected to chamfering, and may be subjected to etching treatment or mirror polishing.
• the downdraw method include a fusion method and a slit downdraw method.
• a magnetic recording layer can be formed on a glass substrate at a high temperature, so that the recording density of the magnetic disk can be increased.
• the glass substrate on which the magnetic recording layer is formed has a high specific elastic modulus and is less likely to cause surface roughness in a polishing process or a cleaning process. Can be obtained.
• the glass substrate for an information recording medium of the present invention is a glass substrate that can form a magnetic recording layer at a high temperature and can increase the density of the magnetic disk.
• the glass substrate for information recording medium of the present invention is less likely to cause surface roughness with respect to an acidic polishing slurry liquid (hereinafter referred to as acid solution) in the glass substrate polishing step or the like, and the glass substrate for information recording medium of the present invention. It becomes possible to manufacture a high recording density information recording medium with high productivity. If the glass substrate is prone to surface roughness with respect to the acid solution, an alternative to an acid solution having a high pH is required. In the polishing of a glass substrate using an acid solution having a high pH, the polishing rate decreases, and it takes time for a predetermined polishing amount, resulting in a decrease in productivity. Alternatively, the polishing time until surface roughness occurs is shortened and the predetermined surface roughness is not reached.
• acid solution acidic polishing slurry liquid
• the glass substrate for information recording medium of the present invention is less likely to cause surface roughness with respect to an alkaline liquid in a glass substrate cleaning process or the like, and a high recording density information recording medium is obtained by using the glass substrate for information recording medium of the present invention.
• the glass substrate for information recording medium of the present invention is not only capable of forming a magnetic recording layer at a high temperature but also a glass substrate for information recording medium excellent in solubility, that is, mass productivity.
• the material of the magnetic recording layer for use in the production method of the magnetic disk of the present invention is a FePt or SmCo 5 is typical.
• the magnetic recording layer is formed on a glass substrate whose temperature is typically 550 ° C. or higher.
• the temperature of the glass substrate is preferably 600 ° C. or higher or 650 ° C. or higher, as necessary.
• the temperature of this glass substrate shall be 800 degrees C or less normally.
• a layer such as an underlayer is formed between the glass substrate and the magnetic recording layer, and if necessary, a protective film or the like is formed on the magnetic recording layer. Layers are formed.
• the temperature is 650 ° C. or higher so that deformation of the glass during formation is suppressed and the magnetic disk can be read and written normally. More preferably, it is 700 ° C. or higher, particularly preferably 750 ° C. or higher, and typically 800 ° C. or lower.
• the temperature T 2 at which 10 2 dPa ⁇ s is obtained is preferably 1710 ° C. or lower. More preferably, it is 1700 degrees C or less, More preferably, it is 1680 degrees C or less.
• the density of the glass of the present invention stabilizes the disk rotation, reduces the load on the rotary motor, reduces the power consumption, reduces the exhaust heat load due to the heat generated by the motor, and makes the glass less susceptible to damage. since preferably 2.7 g / cm 3 or less, typically is 2.62 g / cm 3 or less.
• the specific elastic modulus of the substrate glass is preferably 32 MNm / kg or more in order to prevent a fluttering phenomenon during high-speed rotation and to cope with a high recording density. More preferably, it is 32.5 MNm / kg or more, More preferably, it is 33 MNm / kg or more.
• the acid resistance index A of the substrate glass is preferably 0.025 nm / h or less in order to correspond to a high recording density without causing a phenomenon such as surface roughness in a polishing process or the like. More preferably, it is 0.02 nm / h or less.
• the alkali resistance index B of the substrate glass is preferably 0.28 nm / h or less in order to cope with a high recording density without causing a phenomenon such as surface roughness in a cleaning process or the like. More preferably, it is 0.27 nm / h or less.
• the acid resistance index A is determined by the following measurement method.
• a measurement sample is obtained by mirror-polishing both surfaces of a glass plate having a thickness of 1 to 2 mm and a size of 4 cm square with colloidal silica and mirror-polishing end surfaces with cerium oxide abrasive grains. This is immersed in an aqueous HNO 3 solution having a pH of 2 (0.01 mol / liter) kept at room temperature for 3 hours.
• the amount of Si eluted in the aqueous solution is analyzed by ICP mass spectrometry to obtain a measured value.
• the etching rate of the glass is calculated from the following formula from the amount of eluted Si, the content of SiO 2 in the glass and the density of the glass.
• the unit of the acid resistance index A is nm / h
• L1 is the amount of the eluted Si per unit area of the glass plate
• the unit is ⁇ g / cm 2
• d is the density of the glass
• the unit is g / cm 3
• P SiO in the glass.
• the unit of the mass percentage display content is 2.
• the alkali resistance index B is determined by the following measurement method.
• a measurement sample is obtained by mirror-polishing both surfaces of a glass plate having a thickness of 1 to 2 mm and a size of 4 cm square with colloidal silica and mirror-polishing end surfaces with cerium oxide abrasive grains. This is immersed in an aqueous NaOH solution having a pH of 12 (0.01 mol / liter) kept at room temperature for 3 hours while applying an ultrasonic wave of 100 kHz. The amount of Si eluted in the aqueous solution is analyzed by ICP mass spectrometry to obtain a measured value.
• the etching rate of the glass is calculated from the following formula from the amount of eluted Si, the content of SiO 2 in the glass and the density of the glass.
• the acid resistance index B is in units of nm / h
• L2 is the amount of eluted Si per unit area of the glass plate
• the unit is ⁇ g / cm 2
• d is the density of the glass
• the unit is g / cm 3
• P is the SiO in the glass.
• the unit of the mass percentage display content is 2.
• composition of the glass of the present invention will be described using the mole percentage display content unless otherwise specified.
• SiO 2 is an essential component. SiO 2 is 60% or more in order to keep basic chemical durability in order to reduce the weight of the substrate and make it difficult to be damaged. Preferably it is 63% or more, More preferably, it is 65% or more, More preferably, it is 66% or more. On the other hand, the viscosity of the glass is lowered, the solubility is made good, and it is made 75% or less in order to improve the chemical durability in the composition near the present invention. Preferably it is 71% or less, More preferably, it is 70% or less, More preferably, it is 69% or less.
• Al 2 O 3 is an essential component.
• Al 2 O 3 improves heat resistance, suppresses phase separation, maintains 7% or more to maintain the smoothness of the substrate surface after polishing and cleaning the substrate, and maintains resistance to scratches.
• it is 9% or more, more preferably 11% or more, more preferably more than 12%, more preferably more than 12.5%.
• Al 2 O 3 is made 17% or less in order to improve the glass solubility.
• it is 16% or less, More preferably, it is 15% or less, More preferably, it is 14% or less.
• the content of Al 2 O 3 is preferably greater than 18 wt%.
• B 2 O 3 is not an essential component, but may be contained because it has an effect of improving the solubility and fragility of glass. Maintenance of acid-resistant, and less than 2% for the improvement of T A. Preferably it is 1.5% or less, More preferably, it is 1.0% or less, More preferably, it is 0.5% or less.
• MgO, CaO, SrO and BaO are components that improve the solubility of the glass and improve the acid resistance and alkali resistance, and any one or more components must contain more than 18% in total (RO) amount. Preferably it is 18.5% or more, more preferably 19% or more.
• the RO amount is set to 26% or less in order to improve devitrification characteristics and make it difficult to be damaged. Preferably it is 24% or less, more preferably 22% or less.
• MgO + CaO is preferably 20% or less. More preferably, it is 18% or less.
• the value obtained by dividing the content of SiO 2 (mole percentage) by the total amount RO of the contents of MgO, CaO, SrO and BaO (mole percentage) increases the specific elastic modulus and improves acid resistance and alkali resistance.
• T 2 the temperature at which the viscosity becomes 10 2 dPa ⁇ s
• it is preferably 4.3 or less. More preferably, it is 4.1 or less, More preferably, it is 3.9 or less.
• MgO is a component that increases the Young's modulus and has the effect of increasing the rigidity of the glass. More preferably, it is 7% or more.
• the glass of the present invention consists essentially of the above seven components, but may contain other components as long as the object of the present invention is not impaired. However, even in that case, the total content of these components is less than 5% for maintaining resistance to scratches, maintaining acid resistance, alkali resistance, and maintaining specific elasticity.
• components other than the above seven components will be exemplarily described.
• ZnO is a component having the same effect as MgO, CaO, SrO and BaO, and may be contained in a range of less than 5%.
• the total content of ZnO and RO is preferably more than 18% and 26% or less.
• Li 2 O since Na 2 O and K 2 O decreases the T A, it is preferable that the total content of these three components do not contain less than 1%, or substantially.
• the total content thereof is preferably 3% or less. More preferably, it is 2% or less, particularly preferably 1% or less, and most preferably 0.3% or less.
• SO 3 , F, Cl, As 2 O 3 , Sb 2 O 3, SnO 2 and the like are typical components as fining agents.
• MgCa is the total content of MgO and CaO
• RO is the total content of MgO, CaO, SrO and BaO.
• the acid resistance index A was determined by the following measurement method.
• a glass sample having a thickness of 1 to 2 mm and a size of 4 cm square was mirror-polished on both sides with colloidal silica, and the end surface was mirror-polished with cerium oxide abrasive grains as a measurement sample. This was immersed in an aqueous HNO 3 solution having a pH of 2 (0.01 mol / liter) kept at room temperature for 3 hours.
• the amount of Si eluted in the aqueous solution was analyzed by ICP mass spectrometry to obtain a measured value.
• the etching rate of the glass was calculated by the following formula from the amount of dissolved Si, the content of SiO 2 in the glass, and the density of the glass.
• the unit of the acid resistance index A is nm / h
• L1 is the amount of the eluted Si per unit area of the glass plate
• the unit is ⁇ g / cm 2
• d is the density of the glass
• the unit is g / cm 3
• P SiO in the glass.
• the unit of the mass percentage display content is 2.
• the alkali resistance index B was determined by the following measurement method.
• a glass sample having a thickness of 1 to 2 mm and a size of 4 cm square was mirror-polished on both sides with colloidal silica, and the end surface was mirror-polished with cerium oxide abrasive grains as a measurement sample.
• This was immersed in an aqueous NaOH solution having a pH of 12 (0.01 mol / liter) kept at room temperature for 3 hours while applying an ultrasonic wave of 100 kHz.
• the amount of Si eluted in the aqueous solution was analyzed by ICP mass spectrometry to obtain a measured value.
• the etching rate of the glass was calculated by the following formula from the amount of dissolved Si, the content of SiO 2 in the glass, and the density of the glass.
• the unit of the alkali resistance index B is nm / h
• L2 is the amount of the eluted Si per unit area of the glass plate
• the unit is ⁇ g / cm 2
• d is the density of the glass
• the unit is g / cm 3
• P is the SiO in the glass.
• the unit of the mass percentage display content is 2.
• Examples 1 to 6 are examples of the substrate glass used in the present invention.
• Example 7 is a substrate glass for comparison.
• the present invention can be used for manufacturing a magnetic disk and a glass substrate for an information recording medium.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Geochemistry & Mineralogy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Ceramic Engineering (AREA)
• Inorganic Chemistry (AREA)
• Glass Compositions (AREA)
• Manufacturing Of Magnetic Record Carriers (AREA)
• Magnetic Record Carriers (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=49711961

Family Applications (1)

Country Status (4)

Cited By (6)

Citations (4)

Family Cites Families (4)

• 2013
  • 2013-05-31 JP JP2014519971A patent/JP5907259B2/ja active Active
  • 2013-05-31 CN CN201710066079.1A patent/CN107032603B/zh active Active
  • 2013-05-31 WO PCT/JP2013/065285 patent/WO2013183569A1/fr not_active Ceased
  • 2013-05-31 CN CN201380029770.2A patent/CN104364212A/zh active Pending
  • 2013-05-31 SG SG11201408098RA patent/SG11201408098RA/en unknown

Patent Citations (4)

Also Published As

Similar Documents

Legal Events