WO2017081848A1 - 磁気記録用磁性粉の分別方法、磁気記録用磁性粉の分別装置、および磁気記録媒体の製造方法 - Google Patents
磁気記録用磁性粉の分別方法、磁気記録用磁性粉の分別装置、および磁気記録媒体の製造方法 Download PDFInfo
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- WO2017081848A1 WO2017081848A1 PCT/JP2016/004729 JP2016004729W WO2017081848A1 WO 2017081848 A1 WO2017081848 A1 WO 2017081848A1 JP 2016004729 W JP2016004729 W JP 2016004729W WO 2017081848 A1 WO2017081848 A1 WO 2017081848A1
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- 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
- G11B5/842—Coating a support with a liquid magnetic dispersion
- G11B5/845—Coating a support with a liquid magnetic dispersion in a magnetic field
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- 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
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/714—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the dimension of the magnetic particles
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- 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
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
- G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
- G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
- G11B5/70678—Ferrites
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- 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
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- 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
- G11B5/842—Coating a support with a liquid magnetic dispersion
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
- H01F41/16—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates the magnetic material being applied in the form of particles, e.g. by serigraphy, to form thick magnetic films or precursors therefor
Definitions
- the present technology relates to a magnetic powder separation method for magnetic recording, a magnetic powder separation device for magnetic recording, and a method for manufacturing a magnetic recording medium.
- the particle size In the magnetic powder for magnetic recording, it is necessary to set the particle size to at least 1/2 or less of the recording wavelength. However, when the particle size is reduced, a phenomenon called superparamagnetism occurs, and the magnetic properties are rapidly deteriorated as the particle size is reduced (see FIG. 6). For this reason, when many particles showing superparamagnetism are contained in the magnetic powder, there is a risk of deteriorating the characteristics of the entire magnetic powder. Thus, a technique for reducing superparamagnetic particles contained in magnetic powder is desired.
- Patent Document 1 describes a technique for classifying magnetic powder according to particle size using a liquid cyclone.
- Patent Document 2 describes the use of classified magnetic powder for a magnetic recording medium. “Classification”, for example, in the explanation of the second edition of the World Encyclopedia, is that fluid particles are used to separate powder particles according to their particle sizes.
- the object of the present technology is to provide a magnetic powder separation method, a magnetic powder separation device, and a magnetic recording medium manufacturing method capable of reducing superparamagnetic particles from the magnetic recording magnetic powder. There is to do.
- the first technique is to apply a magnetic field to a liquid in which magnetic powder for magnetic recording is dispersed, and to move the magnetic field application position relative to the liquid relatively. This is a method for separating powder.
- the second technique is to move at least one of a storage unit that stores a liquid in which magnetic powder for magnetic recording is dispersed, a magnetic field application unit that applies a magnetic field to the liquid, and a storage unit and a magnetic field application unit. It is a magnetic powder sorting device including a moving unit that relatively moves a magnetic field application position.
- magnetic powder for magnetic recording is dispersed, a magnetic field application unit that applies a magnetic field to the liquid stored in the storage unit, and at least one of the storage unit and the magnetic field application unit is moved to It is a magnetic powder sorting device comprising a moving unit that relatively moves an application position.
- a magnetic field is applied to a liquid in which magnetic powder for magnetic recording is dispersed, the magnetic field application position is relatively moved with respect to the liquid, and the liquid at the applied position of the magnetic field after the liquid is moved. And forming a magnetic layer using the magnetic powder for magnetic recording contained in the taken liquid.
- the liquid further includes taking the liquid at the applied position of the magnetic field after movement, and a part of the liquid so as to include the applied position of the magnetic field after movement. It is more preferable that the method further includes separating the liquid and taking a part of the liquid after the separation.
- the liquid is stored in a storage unit having at least a first chamber and a second chamber, and the movement of the magnetic field application position is a movement from the first chamber to the second chamber.
- the movement of the magnetic field application position is a movement from the first chamber to the second chamber.
- the liquid is accommodated in the accommodating portion, and the movement is movement from one end portion of the accommodating portion to the other end portion.
- the magnetic field is preferably applied by a magnetic field application unit held obliquely with respect to the direction of movement.
- the magnetic field during movement is not less than an external magnetic field equivalent to 1/20 of the coercive force Hc of the magnetic powder for magnetic recording and not more than an external magnetic field equivalent to the coercive force Hc of the magnetic powder for magnetic recording. It is preferable.
- the magnetic field is preferably an alternating magnetic field.
- the frequency of the alternating magnetic field during movement is preferably 0.1 Hz to 100 Hz.
- the magnetic powder for magnetic recording is preferably hexagonal ferrite magnetic powder.
- the storage unit is configured to be able to separate a part of the storage unit, and the moving unit can move the application position of the magnetic field from a part of the storage unit to a part of the storage unit.
- the moving unit can move the application position of the magnetic field from a part of the storage unit to a part of the storage unit.
- the storage unit has at least a first chamber and a second chamber, and the moving unit moves the application position of the magnetic field from the first chamber to the second chamber.
- the accommodating portion preferably has a rectangular parallelepiped shape or a cylindrical shape.
- the magnetic field application unit is preferably held obliquely with respect to the direction of movement so that the application position of the magnetic field moves from one end part to the other end part of the housing part with movement. .
- particles exhibiting superparamagnetism can be reduced from the magnetic powder for magnetic recording.
- FIG. 1A is a side view illustrating a configuration example of a magnetic powder sorting apparatus for magnetic recording according to the first embodiment of the present technology.
- FIG. 1B is a top view illustrating a configuration example of a magnetic powder sorting apparatus according to the first embodiment of the present technology.
- FIG. 2A is a perspective view showing one configuration example of a magnetic powder sorting apparatus according to the second embodiment of the present technology.
- FIG. 2B is a top view illustrating a configuration example of a magnetic powder sorting apparatus for magnetic recording according to the second embodiment of the present technology.
- FIG. 3A is a side view showing a configuration example of a magnetic powder sorting apparatus according to a third embodiment of the present technology.
- FIG. 3B is a top view illustrating a configuration example of a magnetic powder sorting apparatus according to the third embodiment of the present technology.
- FIG. 4 is a cross-sectional view illustrating a configuration example of a magnetic recording medium according to the fourth embodiment of the present technology.
- FIG. 5 is a side view illustrating the configuration of the magnetic powder sorting apparatus according to the embodiment.
- FIG. 6 is a graph showing an example of the relationship between the particle size and magnetic properties of barium ferrite magnetic powder.
- the magnetic powder separation device 10 includes a storage unit 11 that stores a dispersion liquid, and a magnetic field applied to the dispersion liquid stored in the storage unit 11.
- a pair of magnetic field applying units 12a and 12b to be applied a moving unit 13a and 13b for moving the magnetic field applying unit 12a and 12b to move a magnetic field applying position with respect to the dispersion liquid, and a supply for supplying the dispersion liquid to the storage unit 11 Part 14, discharge parts 15 a and 15 b for discharging the dispersion, and support part 16 for supporting the storage part 11.
- the magnetic field application units 12a and 12b, the moving units 13a and 13b, the supply unit 14 and the discharge units 15a and 15b are connected to a control unit (not shown) and controlled by this control unit.
- the control unit includes an operation panel, a personal computer, or the like, through which an operator can operate the sorting apparatus 10.
- the dispersion liquid is a liquid containing a solvent and magnetic powder dispersed in the solvent. It is preferable that the dispersion liquid further contains a dispersant. It is because it becomes easy to disperse
- the dispersion may further contain additives other than the dispersant.
- the magnetic powder is, for example, a powder of nanomagnetic particles such as hexagonal ferrite, cobalt ferrite, or ⁇ iron oxide ( ⁇ -Fe 2 O 3 ).
- the hexagonal ferrite for example, barium ferrite can be used, and a part of barium may be substituted with at least one of strontium and calcium.
- Solvents for dispersing magnetic powder are, for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, alcohol solvents such as methanol, ethanol, propanol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate.
- ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone
- alcohol solvents such as methanol, ethanol, propanol, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate.
- Ester solvents such as ethylene glycol acetate, ether solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran and dioxane, aromatic hydrocarbon solvents such as benzene, toluene and xylene, methylene chloride, ethylene chloride, carbon tetrachloride , Halogenated hydrocarbon solvents such as chloroform and chlorobenzene. These may be used alone or in combination of two or more.
- the dispersion includes a magnetic powder whose magnetic properties have been greatly reduced by reducing the particle size (ie, a magnetic powder exhibiting superparamagnetism or a magnetic property close thereto, hereinafter simply referred to as “superparamagnetic magnetic powder”), and a small amount.
- Magnetic powder that does not have a significant decrease in magnetic properties as described above due to particle size ie, magnetic powder that has not yet exhibited superparamagnetism or magnetic properties close thereto, hereinafter simply referred to as “ferromagnetic magnetic powder” (See FIG. 6).
- the accommodating portion 11 is a container having a rectangular parallelepiped shape. It is preferable that the distance between both side surfaces of the accommodating portion 11 facing the magnetic field applying portions 12a and 12b is narrow. This is because a magnetic field can be efficiently applied to the dispersion.
- the accommodating part 11 has 1st, 2nd area
- a supply unit 14 is provided above the first region R1 of the storage unit 11, a discharge unit 15a is provided at the bottom of the first region R1 of the storage unit 11, and a bottom of the second region R2 of the storage unit 11 is provided at the bottom.
- a discharge part 15b is provided.
- the magnetic field applying units 12a and 12b are arranged to face each other with a predetermined interval so as to sandwich the accommodating unit 11 therebetween.
- the magnetic field application units 12a and 12b are electromagnets and may be applied with either an AC magnetic field or a DC magnetic field, but an AC magnetic field can be applied from the viewpoint of suppressing sticking of magnetic powder due to the magnetic field. Those are preferred.
- the moving parts 13a and 13b are linear motors or the like and have support parts 13c and 13d that can move linearly, respectively.
- Magnetic field application units 12a and 12b are supported by the support units 13c and 13d, respectively.
- the moving parts 13a and 13b are arranged so that the magnetic field applying parts 12a and 12b are linear along the both side surfaces of the containing part 11 from one end to the other end of the containing part 11, that is, from the region R1 to the direction R2. Move to.
- a dispersion liquid in which magnetic powder is dispersed in a solvent is supplied to the storage unit 11 via the supply unit 14.
- the magnetic field application units 12 a and 12 b located at one end of the storage unit 11 are driven to apply a magnetic field to the dispersion from both side surfaces of the storage unit 11.
- the moving units 13a and 13b are driven so that the magnetic field application units 12a and 12b are linearly extended from one end to the other end of the storage unit 11 along both side surfaces of the storage unit 11. Move to. Thereby, the application position of the magnetic field is linearly moved from one end to the other end of the accommodating portion 11, that is, from the first region R1 to the second region R2.
- the force attracted to the magnetic field is greatly different between the ferromagnetic magnetic powder dispersed in the dispersion and the superparamagnetic magnetic powder. That is, among the magnetic powders dispersed in the dispersion, the ferromagnetic magnetic powder is more easily attracted to the magnetic field than the superparamagnetic magnetic powder. For this reason, a lot of ferromagnetic magnetic powder tends to gather at the magnetic field application position by the magnetic field application units 12a and 12b, and a lot of superparamagnetic magnetic powder tends to remain in the non-magnetic field application portion after the applied magnetic field has passed. . Therefore, the dispersion liquid in the second region R2 contains more ferromagnetic magnetic powder than the dispersion liquid in the dispersion liquid in the first region R1. That is, superparamagnetic magnetic powder is reduced in the dispersion in the second region R2.
- the magnetic field during movement of the magnetic field application units 12a and 12b is preferably not less than an external magnetic field equivalent to 1/20 of the coercive force Hc of the magnetic powder and not more than an external magnetic field equivalent to the coercive force Hc of the magnetic powder. If the magnetic field is less than the lower limit, the effect of separating magnetic powder by the magnetic properties (coercive force Hc) may be reduced. On the other hand, if the magnetic field exceeds the above upper limit, the magnetization induced by superparamagnetism increases, and the difference in magnetization between superparamagnetic magnetic powder and ferromagnetic magnetic powder becomes small, which may reduce the separation effect. is there.
- the frequency of the alternating magnetic field when moving the magnetic field application units 12a and 12b is 0.1 Hz to 100 Hz. If the frequency is less than 0.1 Hz, it is necessary to slow down the moving speed at the time of movement, which may increase the time required for separating the magnetic powder. On the other hand, if the frequency exceeds 100 Hz, eddy current loss may increase.
- the magnetic field application units 12a and 12b and the moving unit 13a After inserting the partition plate 17 between the first and second regions R1 and R2 and spatially separating the first and second regions R1 and R2, the magnetic field application units 12a and 12b and the moving unit 13a, The drive of 13b is stopped. Next, the dispersion in the first region R1 is discharged through the discharge unit 15a, and the dispersion in the second region R2 is discharged through the discharge unit 15b. Next, if necessary, the dispersion discharged from each of the discharge portions 15a and 15b may be individually dried to obtain magnetic powder.
- a magnetic field is applied to the dispersion liquid in which the magnetic powder is dispersed, and the application position of the magnetic field with respect to the dispersion liquid is relatively moved from the first region R1 to the second region R2 of the storage unit 11.
- the dispersion in the first region R1 contains superparamagnetic magnetic powder at a higher concentration than the dispersion in the second region R2, whereas the second region R2
- This dispersion liquid contains ferromagnetic magnetic powder at a higher concentration than the dispersion liquid in the first region R1.
- the dispersion liquid of the first and second regions R1 and R2 is discharged by the discharge portions 15a and 15b, respectively, thereby superparamagnetism.
- the magnetic powder with reduced magnetic powder and the magnetic powder with reduced ferromagnetic magnetic powder can be separated. That is, it is possible to separate magnetic powder exhibiting good magnetic characteristics from magnetic powder exhibiting poor magnetic characteristics.
- good magnetic properties mean good magnetic properties in terms of use in the recording layer of a magnetic recording medium. Specifically, it means that the coercive force Hc is good.
- the magnetic powder is separated by utilizing the fact that the ferromagnetic magnetic powder and the superparamagnetic magnetic powder have different forces attracted to the magnetic field.
- magnetic powder can be classified based on magnetic properties. Therefore, it is also possible to sort out magnetic powder whose magnetic properties have been reduced due to causes other than particle size variation.
- the magnetic field When the magnetic field is smaller than the magnetic field required for saturation of the magnetic powder, a magnetic force corresponding to the remanent magnetization component is generated in the magnetic powder, and this force attracts the magnetic powder to a higher magnetic field region. At this time, there is a large difference in force between the superparamagnetic powder and the ferromagnetic powder. By removing the magnetic powder far from the position after moving the magnetic field application position, the magnetic powder does not rely on classification. Therefore, the superparamagnetic component can be reduced.
- the accommodating portion 11 may have first to third regions, and the partition plate 17 serving as a separation portion may be configured to be able to separate the first to third regions.
- the magnetic powder sorting device 20 includes a cylindrical housing portion 21 and magnetic field application units 12 a and 12 b along the cylindrical surface of the housing portion 21. And a moving unit 22 for moving the image.
- the accommodating portion 21, the magnetic field applying portions 12 a and 12 b, and the moving portion 22 are supported by the support base 23.
- the magnetic field application units 12a and 12b, the moving unit 22, the supply unit 14, and the discharge units 15a and 15b are connected to a control unit (not shown) and are controlled by the control unit.
- the accommodating part 21 has two first regions R1 and two second regions R2. 1st, 2nd area
- region R1, R2 is provided so that 1st, 2nd area
- FIG. The accommodating part 21 is comprised so that isolation
- the moving part 22 has a ring-shaped table 22a that rotates, and the accommodating part 21 is fixed on the table 22a.
- the accommodating part 21 rotates with respect to the magnetic field applying parts 12a and 12b whose positions are fixed.
- the cylindrical container 21 is rotated and moved with respect to the fixed magnetic field application units 12a and 12b, and the first and second regions R1 and R2 are used to separate the magnetic powder. This is the same as the first embodiment. However, it is preferable to move the magnetic field application units 12a and 12b to the second region R2 after moving the entire first region R1.
- the magnetic powder separation device 30 includes a moving unit 32 that moves a plurality of storage units 31 that store the dispersion, and a moving storage unit 31 that moves.
- the moving unit 32, the magnetic field applying units 33a and 33b, and the supply unit 34 are connected to a control unit (not shown) and are controlled by the control unit.
- the accommodating part 31 is a rectangular parallelepiped container, and one surface is opened to form an open part 31a. On one side of the open portion 31a of the accommodating portion 31, a rectangular extending portion 31b extending outside the open portion 31a is provided.
- the opening portion 31 a is on the upper side, and the extending portion 31 b is positioned between the adjacent accommodating portions 31 and is supplied to the moving portion 32.
- the moving unit 32 is a conveying device such as a belt conveyor, and includes a belt 32a and a plurality of rollers 32b.
- the magnetic field application units 33a and 33b are provided on a moving path along which the storage unit 31 is moved.
- the magnetic field application units 33a and 33b have a long shape, and are provided in parallel with a predetermined interval so that the storage unit 31 moved by the moving unit 32 can pass between the magnetic field application units 33a and 33b.
- the magnetic field application units 33a and 33b are arranged obliquely with respect to the moving direction of the storage unit 31 so that the application position of the magnetic field moves from one end of the storage unit 31 to the other end as the storage unit 31 moves. ing.
- the supply unit 34 supplies the dispersion liquid to the storage unit 31 that is moved by the moving unit 32 through the open portion 31a.
- the collection unit 35 collects the dispersion liquid stored in the storage unit 31 that has been moved by the moving unit 32.
- the collection unit 35 includes a first collection unit 35a and a second collection unit 35b.
- the second recovery unit 35b the dispersion on the other end side of the storage unit 31, that is, the dispersion at the magnetic field application position is recovered.
- recovery part 35a the dispersion liquid in the one end part side of the accommodating part 31, ie, the dispersion liquid in a non-magnetic field application position, is collect
- the supply unit 34 supplies the dispersion from the opening unit 31a.
- the storage unit 31 is moved, and a magnetic field is applied to one end of the storage unit 31 by the magnetic field application units 33a and 33b. Thereafter, with the movement of the supply unit 34, the magnetic field application position by the magnetic field application units 33 a and 33 b moves from one end of the housing unit 31 toward the other end.
- the accommodating part 31 When the accommodating part 31 reaches the other end of the moving path, the accommodating part 31 falls. Thereby, among the dispersion liquid accommodated in the accommodating part 31, the dispersion liquid from the central part of the accommodating part 31 to one end part side (that is, the magnetic field non-application position side) is recovered by the first recovery part 35a. On the other hand, the dispersion liquid on the other end side (that is, on the magnetic field application position side) from the central portion of the accommodating portion 31 is recovered by the second recovery portion 35b. Next, if necessary, the dispersions collected by the first and second collection units 35a and 35b may be individually dried to obtain magnetic powder.
- Modification 1 instead of the long magnetic field application units 33a and 33b, a plurality of magnetic field application units arranged obliquely with respect to the moving direction of the housing unit 31 may be provided.
- a collecting device such as an articulated robot may be provided near the other end of the moving path of the moving unit 32, and the containing unit 31 falling from one end of the moving unit may be collected by the collecting device.
- Modification 3 An overturning device such as an articulated robot is provided near the other end of the moving path of the moving unit 32, and the containing unit 31 that has been moved to one end of the moving path of the moving unit 32 is overturned and accommodated by this overturning device.
- the dispersion liquid that has flowed down from the unit 31 may be recovered by the recovery unit 35.
- the some accommodating part 31 may be fixed to the belt 32a, and the structure by which the several accommodating part 31 is used repeatedly may be sufficient.
- a magnetic recording medium 40 according to the fourth embodiment of the present technology includes a nonmagnetic support 41, an underlayer 42 provided on one main surface of the nonmagnetic support 41, A recording layer 43 provided on the underlayer 42.
- the magnetic recording medium 40 may further include a backcoat layer 44 provided on the other main surface of the nonmagnetic support 41 as necessary.
- the magnetic recording medium 40 may further include a protective layer and a lubricant layer provided on the recording layer 43 as necessary.
- a base layer-forming coating material is prepared by kneading and dispersing a nonmagnetic powder and a binder in a solvent.
- a recording powder for forming a recording layer is prepared by kneading and dispersing magnetic powder, a binder and the like in a solvent.
- magnetic powder what shows the favorable magnetic characteristic sorted in the magnetic powder separation method in any one of the above-mentioned 1st to 3rd embodiment is used. In addition, you may use the thing of the state of a dispersion liquid, without drying.
- a backcoat layer-forming coating material is prepared by kneading and dispersing a binder, inorganic particles, a lubricant, and the like in a solvent.
- a solvent for example, the following solvent, dispersion apparatus, and kneading apparatus can be applied to the preparation of the base layer forming paint, the recording layer forming paint, and the backcoat layer forming paint.
- Examples of the solvent used in the above-mentioned coating preparation include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, alcohol solvents such as methanol, ethanol, and propanol, methyl acetate, ethyl acetate, butyl acetate, and propyl acetate.
- ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone
- alcohol solvents such as methanol, ethanol, and propanol, methyl acetate, ethyl acetate, butyl acetate, and propyl acetate.
- Ester solvents such as ethyl lactate and ethylene glycol acetate, ether solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran and dioxane, aromatic hydrocarbon solvents such as benzene, toluene and xylene, methylene chloride, ethylene chloride, Halogenated hydrocarbon solvents such as carbon tetrachloride, chloroform, chlorobenzene and the like. These may be used alone or in combination of two or more.
- Examples of the kneading apparatus used for the coating preparation described above include a continuous biaxial kneader, a continuous biaxial kneader capable of diluting in multiple stages, a kneader, a pressure kneader, and a roll kneader.
- the present invention is not particularly limited to these devices.
- a dispersing device such as a sonic disperser can be used, but is not particularly limited to these devices.
- the base layer 42 is formed on one main surface of the nonmagnetic support 41 by applying a coating for forming the base layer on one main surface of the nonmagnetic support 41 and drying it.
- the recording layer 43 is formed on the underlayer 42 by applying a recording layer forming paint on the underlayer 42 and drying it.
- the back coat layer 44 is applied to the other main surface of the nonmagnetic support 41 and dried to dry the back coat layer 44 to the other main surface of the nonmagnetic support 41. Form on top. Thereby, a wide magnetic recording medium 40 is obtained.
- the obtained wide magnetic recording medium 40 is rewound around a large-diameter core, and a curing process is performed.
- a calendar process is performed on the wide magnetic recording medium 40 and then cut into a predetermined width. Thereby, the target magnetic recording medium 40 is obtained.
- the step of forming the backcoat layer 44 may be after the calendar process.
- the recording layer 43 is formed by using magnetic powder that exhibits good magnetic properties sorted by the magnetic powder sorting method of any of the first to third embodiments described above. is doing. Thereby, the magnetization reversal region in the short wavelength region becomes clear in magnetic recording, and the S / N ratio is improved.
- a barium ferrite magnetic powder having a holding power of Hc 2700 Oe was dispersed in a solvent to prepare a dispersion.
- the magnetic powder was dispersed into primary particles using a dispersant or the like.
- this dispersion was supplied to the vertical container 51, and an alternating magnetic field was applied from the side surface of the vertical container 51 by the electromagnets 52a and 52b.
- the frequency of the alternating magnetic field was set to 10 Hz, and the magnitude of the magnetic field was set to 1.1 kG (Gauss).
- the electromagnets 52a and 52b were moved from the bottom side to the top of the vertical container 51 while maintaining the application of the alternating magnetic field. After the movement, the dispersion in the upper region of the vertical container 51 to which an alternating magnetic field was applied was collected with a spoid 53.
- the present technology can also employ the following configurations.
- a method for separating magnetic powder for magnetic recording comprising relatively moving a position of application of a magnetic field to the liquid.
- the liquid is stored in a storage unit having at least a first chamber and a second chamber, The method for separating magnetic powder for magnetic recording according to (1), wherein the movement of the application position of the magnetic field is movement from the first chamber to the second chamber. (5) After the movement, the first chamber and the second chamber are separated, The method for fractionating magnetic powder for magnetic recording according to (4), further comprising: taking the liquid in the second chamber. (6) The liquid is stored in a storage unit, The said movement is a separation method of the magnetic powder for magnetic recording as described in (1) which is a movement from the one end part of the said accommodating part to the other end part.
- the magnetic field separation method according to (1) wherein the magnetic field is applied by a magnetic field application unit that is held obliquely with respect to the moving direction.
- the magnetic field at the time of movement is not less than an external magnetic field equivalent to 1/20 of the coercive force Hc of the magnetic powder for magnetic recording and not more than an external magnetic field equivalent to the coercive force Hc of the magnetic powder for magnetic recording.
- a method for separating magnetic powder for magnetic recording according to any one of the above. (9) The magnetic field separation method according to any one of (1) to (8), wherein the magnetic field is an alternating magnetic field.
- the frequency of the alternating magnetic field at the time of the movement is 0.1 Hz or more and 100 Hz or less
- a magnetic powder sorting apparatus comprising: a moving unit that moves at least one of the storage unit and the magnetic field applying unit to relatively move a magnetic field application position with respect to the liquid.
- a magnetic powder sorting apparatus comprising: a moving unit that moves at least one of the storage unit and the magnetic field applying unit to relatively move a magnetic field application position with respect to the liquid.
- the housing portion is configured to be separable from a part of the housing portion,
- the said moving part is a magnetic powder separation apparatus as described in (12) which moves the application position of the said magnetic field from the part outside the said accommodating part to a part of the said accommodating part.
- the magnetic powder separation device for magnetic recording according to (14) further comprising a discharge unit that discharges the dispersion liquid in a part of the storage unit.
- the accommodating portion has at least a first chamber and a second chamber,
- the magnetic field application unit is held obliquely with respect to the direction of movement (13) so that the application position of the magnetic field moves from one end to the other end of the accommodation unit with the movement.
- the magnetic powder separation apparatus for magnetic recording described.
- a method of manufacturing a magnetic recording medium comprising: forming a magnetic layer using magnetic powder for magnetic recording contained in the taken liquid.
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- Manufacturing Of Magnetic Record Carriers (AREA)
- Thin Magnetic Films (AREA)
Abstract
Description
1 第1の実施形態(磁気記録用磁性粉(以下単に「磁性粉」という。)の分別装置および分別方法の例)
2 第2の実施形態(磁性粉の分別装置および分別方法の例)
3 第3の実施形態(磁性粉の分別装置および分別方法の例)
4 第4の実施形態(磁気記録媒体の製造方法の例)
[磁性粉の分別装置]
図1A、図1Bに示すように、本技術の第1の実施形態に係る磁性粉の分別装置10は、分散液を収容する収容部11と、収容部11に収容された分散液に磁場を印加する一対の磁場印加部12a、12bと、磁場印加部12a、12bを移動して、分散液に対する磁場の印加位置を移動する移動部13a、13bと、分散液を収容部11に供給する供給部14と、分散液を排出する排出部15a、15bと、収容部11を支持する支持部16とを備える。なお、図1Aでは、移動部13a、13bの図示を省略している。磁場印加部12a、12b、移動部13a、13b、供給部14および排出部15a、15bは、図示しない制御部に接続されており、この制御部によって制御される。制御部は、操作パネルまたはパーソナルコンピュータ等を備え、これらを介して作業者が分別装置10を操作可能となっている。
分散液は、溶媒と、溶媒に分散された磁性粉とを含む液体である。分散液が、分散剤をさらに含んでいることが好ましい。磁性粉を一次粒子の状態にまで分散させ易くなるからである。分散液が、分散剤以外の添加剤をさらに含んでいてもよい。磁性粉は、例えば、六方晶フェライト、コバルトフェライトまたはε酸化鉄(ε-Fe2O3)などのナノ磁性粒子の粉末である。六方晶フェライトとしては、例えばバリウムフェライトを用いることができ、バリウムの一部がストロンチウムおよびカルシウムのうちの少なくとも1種で置換されていてもよい。磁性粉を分散させる溶媒は、例えば、アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノンなどのケトン系溶媒、メタノール、エタノール、プロパノールなどのアルコール系溶媒、酢酸メチル、酢酸エチル、酢酸ブチル、酢酸プロピル、乳酸エチル、エチレングリコールアセテートなどのエステル系溶媒、ジエチレングリコールジメチルエーテル、2-エトキシエタノール、テトラヒドロフラン、ジオキサンなどのエーテル系溶媒、ベンゼン、トルエン、キシレンなどの芳香族炭化水素系溶媒、メチレンクロライド、エチレンクロライド、四塩化炭素、クロロホルム、クロロベンゼンなどのハロゲン化炭化水素系溶媒などである。これらは単独で用いてもよいし、2種以上混合して用いてもよい。
収容部11は、直方体状を有する容器である。磁場印加部12a、12bとそれぞれ対向する収容部11の両側面の間の距離は、狭い方が好ましい。分散液に対して効率的に磁場を印加できるからである。収容部11は、第1、第2領域R1、R2を有し、分離部としての仕切板17により、第1、第2領域R1、R2間を分離可能に構成されている。収容部11の第1領域R1の上部には供給部14が設けられ、収容部11の第1領域R1の底部には排出部15aが設けられ、収容部11の第2領域R2の底部には排出部15bが設けられている。
磁場印加部12a、12bは、収容部11を間に挟むようにして所定の間隔離して対向配置されている。磁場印加部12a、12bは、電磁石であり、交流磁場および直流磁場のいずれを印加可能なものであってもよいが、磁場による磁性粉の固着を抑制する観点からすると、交流磁場を印加可能なものが好ましい。
移動部13a、13bは、リニアモータなどであり、直線移動可能な支持部13c、13dをそれぞれ有している。支持部13c、13dにはそれぞれ磁場印加部12a、12bが支持されている。移動部13a、13bはそれぞれ、収容部11の両側面に沿って収容部11の一端部から他端部に向けて、すなわち領域R1からR2の方向に向けて磁場印加部12a、12bを直線的に移動する。
次に、本技術の第1の実施形態に係る磁性粉の分別方法の一例について説明する。
本技術の第1の実施形態では、磁性粉が分散された分散液に磁場を印加し、分散液に対する磁場の印加位置を収容部11の第1領域R1から第2領域R2まで相対的に移動する。磁場の印加位置の移動後において、第1領域R1の分散液は、第2領域R2の分散液に比して高い濃度で超常磁性の磁性粉を含んでいるのに対して、第2領域R2の分散液は、第1領域R1の分散液に比して高い濃度で強磁性の磁性粉を含んでいる。したがって、第1、第2領域R1、R2の間を仕切板17で仕切り分離した後、第1、第2領域R1、R2の分散液をそれぞれ排出部15a、15bにより排出することで、超常磁性の磁性粉が低減された磁性粉と、強磁性の磁性粉が低減された磁性粉とを分別することができる。すなわち、良好な磁気特性を示す磁性粉と、良好でない磁気特性を示す磁性粉とを分別することができる。ここで、良好な磁気特性とは、磁気記録媒体の記録層に用いる観点における良好な磁気特性を意味している。具体的には保磁力Hcが良好であることを意味している。
(変形例1)
上述の第1の実施形態では、固定された収容部11に対して磁場印加部12a、12bを移動させる例について説明したが、収容部11に対する磁場印加部12a、12bの移動は相対移動でよい。すなわち、固定された磁場印加部12a、12bに対して収容部11を移動させるようにしてもよいし、収容部11と磁場印加部12a、12bとを互いに異なる方向に移動させるようにしてもよい。
上述の第1の実施形態では、分離部としての仕切板17により、第1、第2領域R1、R2間を分離可能な構成とする例について説明したが、収容部11が、第1、第2領域R1、R2間に自動で開閉する開閉部を有し、第1、第2領域R1、R2がそれぞれ第1、第2室を構成していてもよい。この場合、開閉部の開閉動作は、図示を省略した制御部により行われる。
上述の第1の実施形態では、磁場印加部12a、12bを収容部11の一端部から他端部まで動かし、磁場印加部12a、12bが停止した他端部にある分散液を取る例について説明したが、磁場印加部12a、12bを収容部11の中央部で最終的に停止させて、中央部にある分散液を取るようにしてもよい。具体的には例えば、磁場印加部12a、12bを収容部11の一端部から他端部まで動かした後に、収容部11の中央部に戻し、中央部にある分散液を取るようにしてもよいし、磁場印加部12a、12bを収容部11の中央部から一端部に移動させた後、他端部に移動し、他端部から中央部に戻し、中央部にある分散液を取るようにしてもよい。この場合、収容部11が、第1~第3領域を有し、分離部としての仕切板17により、第1~第3領域の各領域間を分離可能に構成されていてもよい。
[磁性粉の分別装置]
図2A、図2Bに示すように、本技術の第2の実施形態に係る磁性粉の分別装置20は、円筒状の収容部21と、磁場印加部12a、12bを収容部21円筒面に沿って移動させる移動部22とを備えている。収容部21、磁場印加部12a、12bおよび移動部22は、支持台23に支持されている。なお、第2の実施形態において第1の実施形態と同様の箇所には同一の符号を付して説明を省略する。磁場印加部12a、12b、移動部22、供給部14および排出部15a、15bは、図示しない制御部に接続されており、この制御部によって制御される。
固定された磁場印加部12a、12bに対して円筒状の収容部21を回転移動させ、2つの第1領域R1と2つの第2領域R2を利用して、磁性粉の分別を行う以外は第1の実施形態と同様である。但し、磁場印加部12a、12bを第1領域R1全体に渡って移動させた後に、第2領域R2に移動させることが好ましい。
第2の実施形態では、円筒状の収容部21に設定された2つの第1領域R1と2つの第2領域R2を利用して、磁性粉の分別を行うので、第1の実施形態よりも短い時間でより多くの磁性粉の分別を行うことができる。すなわち、磁性粉の分別効率を向上することができる。
(変形例1)
第2の実施形態では、円筒状の収容部21が第1、第2領域R1をそれぞれ2つ備える構成について説明したが、第1、第2領域R1、R2をそれぞれ3つ以上備える構成を採用してもよい。
[磁性粉の分別装置]
図3に示すように、本技術の第3の実施形態に係る磁性粉の分別装置30は、分散液を収容する複数の収容部31を移動する移動部32と、移動される収容部31に収容された分散液に対して磁場を印加する一対の磁場印加部33a、33bと、分散液を収容部31に供給する供給部34と、収容部31により移動されてきた分散液を回収する回収部35とを備える。移動部32、磁場印加部33a、33bおよび供給部34は、図示しない制御部に接続されており、この制御部によって制御される。
収容部31は、直方体状の容器であり、1つの面が開放されて開放部31aとなっている。収容部31の開放部31aの一辺には、開放部31aの外側に延設された矩形状の延設部31bが設けられている。収容部31を移動部32に供給する際には、開放部31aが上側となるとともに、隣接する収容部31の間に延設部31bが位置するようにして、移動部32に供給される。これにより、供給部34により分散液を収容部31に供給する際に、延設部31bにより隣接する収容部31間に分散液がこぼれ落ちることを抑制できる。
移動部32は、ベルトコンベアなどの搬送装置であり、ベルト32aと複数のローラ32bとを備えている。
磁場印加部33a、33bは、収容部31が移動される移動路に設けられている。磁場印加部33a、33bは、長尺状を有し、移動部32により移動される収容部31が磁場印加部33a、33b間を通過可能なように、所定間隔離して平行に設けられている。
磁場印加部33a、33bは、収容部31の移動に伴って収容部31の一端部から他端部に磁場の印加位置が移動するように、収容部31の移動方向に対して斜めに配置されている。
供給部34は、移動部32により移動される収容部31に、その開放部31aを介して分散液を供給する。
回収部35は、移動部32により移動されてきた収容部31に収容された分散液を回収する。回収部35は、第1回収部35aと第2回収部35bを有している。第2回収部35bでは、収容部31の他端部側にある分散液、すなわち磁場印加位置にある分散液が回収される。第1回収部35aでは、収容部31の一端部側にある分散液、すなわち非磁場印加位置にある分散液が回収される。
まず、移動部32の移動路の一端部に収容部31が供給されると、移動部32は収容部31を所定の距離移動し停止する。停止後、移動部32の移動路の一端部に次の収容部31が供給され、再び所定の距離移動し停止する。この移動と停止の動作が交互に繰り返されることで、収容部31が移動路の一端部から他端部に順次移動されるようになっている。
第3の実施形態では、複数の収容部31を移動しながら、収容部31の移動方向に対して斜めに配置された磁場印加部33a、33bにより磁性粉の分別を行うので、第1の実施形態よりも短い時間でより多くの磁性粉の分別を行うことができる。すなわち、磁性粉の分別効率を向上することができる。
(変形例1)
長尺状の磁場印加部33a、33bに代えて、収容部31の移動方向に対して斜めに配列された複数の磁場印加部を設けるようにしてもよい。
移動部32の移動路の他端部の近くに多関節ロボットなどの回収装置が設けられ、この回収装置により移動部の一端部から落下する収容部31が回収されるようにしてもよい。
移動部32の移動路の他端部の近くに多関節ロボットなど転倒装置が設けられ、この転倒装置により移動部32の移動路の一端部まで移動されてきた収容部31が転倒されて、収容部31から流れ落ちた分散液が回収部35により回収されるようにしてもよい。
複数の収容部31がベルト32aに固定され、複数の収容部31が繰り返し用いられる構成であってもよい。
[磁気記録媒体の構成]
図4に示すように、本技術の第4の実施形態に係る磁気記録媒体40は、非磁性支持体41と、非磁性支持体41の一方の主面上に設けられた下地層42と、下地層42上に設けられた記録層43とを備える。磁気記録媒体40が、必要に応じて、非磁性支持体41の他方の主面上に設けられたバックコート層44をさらに備えるようにしてもよい。また、磁気記録媒体40が、必要に応じて、記録層43上に設けられた保護層および潤滑剤層などをさらに備えるようにしてもよい。
以下、本技術の第4の実施形態に係る磁気記録媒体の製造方法の一例について説明する。
まず、非磁性粉および結着剤などを溶剤に混練、分散させることにより、下地層形成用塗料を調製する。次に、磁性粉および結着剤などを溶剤に混練、分散させることにより、記録層形成用塗料を調製する。磁性粉としては、上述の第1から第3の実施形態のいずれかの磁性粉の分別方法において分別された良好な磁気特性を示すものが用いられる。なお、分散液の状態のものを乾燥せずに用いてもよい。次に、必要に応じて、結着剤、無機粒子および潤滑剤などを溶剤に混練、分散させることにより、バックコート層形成用塗料を調製する。下地層形成用塗料、記録層形成用塗料およびバックコート層形成用塗料の調製には、例えば、以下の溶剤、分散装置および混練装置を適用することができる。
次に、非磁性支持体41の一方の主面上に下地層形成用塗料を塗布して乾燥させることにより、下地層42を非磁性支持体41の一方の主面上に形成する。
次に、下地層42上に記録層形成用塗料を塗布して乾燥させることにより、記録層43を下地層42上に形成する。
次に、必要に応じて、非磁性支持体41の他方の主面上にバックコート層形成用塗料を塗布して乾燥させることにより、バックコート層44を非磁性支持体41の他方の主面上に形成する。これにより、幅広の磁気記録媒体40が得られる。
次に、得られた幅広の磁気記録媒体40を大径コアに巻き直し、硬化処理を行う。次に、幅広の磁気記録媒体40に対してカレンダー処理を行った後、所定の幅に裁断する。これにより、目的とする磁気記録媒体40が得られる。なお、バックコート層44を形成する工程は、カレンダー処理後であってもよい。
本技術の第4の実施形態では、上述の第1から第3の実施形態のいずれかの磁性粉の分別方法において分別された良好な磁気特性を示す磁性粉を用いて、記録層43を形成している。これにより、磁気記録において短波長領域における磁化反転領域が明確となり、S/N比が改善される。
まず、保持力Hc2700Oeのバリウムフェライト磁性粉を溶媒に分散させて分散液を調製した。この際、分散剤等を用いて磁性粉を一次粒子の状態にまで分散させた。次に、この分散液を縦型容器51に供給し、電磁石52a、52bにより縦型容器51の側面から交流磁場を印加した。この際、交流磁場の周波数は10Hz、磁場の大きさは1.1kG(ガウス)に設定された。次に、この交流磁場の印加を保持しつつ、縦型容器51の底部側から上部に向けて電磁石52a、52bを移動させた。移動後、交流磁場が印加されている縦型容器51の上部領域にある分散液をスポイド53で採取した。
(1)
磁気記録用磁性粉が分散された液体に磁場を印加し、
前記液体に対する磁場の印加位置を相対的に移動させる
ことを含む磁気記録用磁性粉の分別方法。
(2)
前記液体のうち、前記移動後の磁場の印加位置にある液体を取る
ことをさらに含む(1)に記載の磁気記録用磁性粉の分別方法。
(3)
前記移動後の磁場の印加位置を含むように前記液体のうちの一部を分離し、
前記分離後に前記液体のうちの一部を取る
ことをさらに含む(2)に記載の磁気記録用磁性粉の分別方法。
(4)
前記液体は、少なくとも第1室と第2室とを有する収容部に収容され、
前記磁場の印加位置の移動は、前記第1室から前記第2室への移動である(1)に記載の磁気記録用磁性粉の分別方法。
(5)
前記移動後に、前記第1室と前記第2室とを分離し、
前記第2室にある液体を取る
ことをさらに含む(4)に記載の磁気記録用磁性粉の分別方法。
(6)
前記液体は、収容部に収容され、
前記移動は、前記収容部の一端部から他端部への移動である(1)に記載の磁気記録用磁性粉の分別方法。
(7)
前記磁場は、前記移動の方向に対して斜めに保持された磁場印加部により印加される(1)に記載の磁気記録用磁性粉の分別方法。
(8)
前記移動時の磁場は、磁気記録用磁性粉の保磁力Hcの1/20相当の外部磁場以上、磁気記録用磁性粉の保磁力Hc相当の外部磁場以下である(1)から(7)のいずれかに記載の磁気記録用磁性粉の分別方法。
(9)
前記磁場は、交流磁場である(1)から(8)のいずれかに記載の磁気記録用磁性粉の分別方法。
(10)
前記移動時の交流磁場の周波数は、0.1Hz以上100Hz以下である(9)に記載の磁気記録用磁性粉の分別方法。
(11)
前記磁気記録用磁性粉は、六方晶フェライト磁性粉である(1)から(10)のいずれかに記載の磁気記録用磁性粉の分別方法。
(12)
磁気記録用磁性粉が分散された液体を収容する収容部と、
前記液体に磁場を印加する磁場印加部と、
前記収容部および前記磁場印加部の少なくとも一方を移動して、前記液体に対する磁場の印加位置を相対的に移動する移動部と
を備える磁気記録用磁性粉の分別装置。
(13)
磁気記録用磁性粉が分散され、収容部に収容された液体に磁場を印加する磁場印加部と、
前記収容部および前記磁場印加部の少なくとも一方を移動して、前記液体に対する磁場の印加位置を相対的に移動する移動部と
を備える磁気記録用磁性粉の分別装置。
(14)
前記収容部は、該収容部の一部を分離可能に構成され、
前記移動部は、前記磁場の印加位置を前記収容部の一部の外から前記収容部の一部まで移動する(12)に記載の磁気記録用磁性粉の分別装置。
(15)
前記収容部の一部にある分散液を排出する排出部をさらに備える(14)に記載の磁気記録用磁性粉の分別装置。
(16)
前記収容部は、少なくとも第1室と第2室とを有し、
前記移動部は、前記磁場の印加位置を前記第1室から前記第2室に移動する(12)に記載の磁気記録用磁性粉の分別装置。
(17)
前記磁場印加部は、前記移動に伴って前記磁場の印加位置が前記収容部の一端部から他端部に移動するように、前記移動の方向に対して斜めに保持されている(13)に記載の磁気記録用磁性粉の分別装置。
(18)
前記収容部は、直方体状または円筒状を有する(12)から(17)のいずれかに記載の磁気記録用磁性粉の分別装置。
(19)
磁気記録用磁性粉が分散された液体に磁場を印加し、
前記液体に対する磁場の印加位置を相対的に移動し、
前記液体のうち、前記移動後の磁場の印加位置にある液体を取り、
取られた前記液体に含まれる磁気記録用磁性粉を用いて磁性層を形成する
ことを含む磁気記録媒体の製造方法。
11、21、31 収容部
12a、12、33a、33b 磁場印加部
13a、13b、21 移動部
R1 第1領域
R2 第2領域
Claims (19)
- 磁気記録用磁性粉が分散された液体に磁場を印加し、
前記液体に対する磁場の印加位置を相対的に移動させる
ことを含む磁気記録用磁性粉の分別方法。 - 前記液体のうち、前記移動後の磁場の印加位置にある液体を取る
ことをさらに含む請求項1に記載の磁気記録用磁性粉の分別方法。 - 前記移動後の磁場の印加位置を含むように前記液体のうちの一部を分離し、
前記分離後に前記液体のうちの一部を取る
ことをさらに含む請求項2に記載の磁気記録用磁性粉の分別方法。 - 前記液体は、少なくとも第1室と第2室とを有する収容部に収容され、
前記磁場の印加位置の移動は、前記第1室から前記第2室への移動である請求項1に記載の磁気記録用磁性粉の分別方法。 - 前記移動後に、前記第1室と前記第2室とを分離し、
前記第2室にある液体を取る
ことをさらに含む請求項4に記載の磁気記録用磁性粉の分別方法。 - 前記液体は、収容部に収容され、
前記移動は、前記収容部の一端部から他端部への移動である請求項1に記載の磁気記録用磁性粉の分別方法。 - 前記磁場は、前記移動の方向に対して斜めに保持された磁場印加部により印加される請求項1に記載の磁気記録用磁性粉の分別方法。
- 前記移動時の磁場は、磁気記録用磁性粉の保磁力Hcの1/20相当の外部磁場以上、磁気記録用磁性粉の保磁力Hc相当の外部磁場以下である請求項1に記載の磁気記録用磁性粉の分別方法。
- 前記磁場は、交流磁場である請求項1に記載の磁気記録用磁性粉の分別方法。
- 前記移動時の交流磁場の周波数は、0.1Hz以上100Hz以下である請求項9に記載の磁気記録用磁性粉の分別方法。
- 前記磁気記録用磁性粉は、六方晶フェライト磁性粉である請求項1に記載の磁気記録用磁性粉の分別方法。
- 磁気記録用磁性粉が分散された液体を収容する収容部と、
前記液体に磁場を印加する磁場印加部と、
前記収容部および前記磁場印加部の少なくとも一方を移動して、前記液体に対する磁場の印加位置を相対的に移動する移動部と
を備える磁気記録用磁性粉の分別装置。 - 磁気記録用磁性粉が分散され、収容部に収容された液体に磁場を印加する磁場印加部と、
前記収容部および前記磁場印加部の少なくとも一方を移動して、前記液体に対する磁場の印加位置を相対的に移動する移動部と
を備える磁気記録用磁性粉の分別装置。 - 前記収容部は、該収容部の一部を分離可能に構成され、
前記移動部は、前記磁場の印加位置を前記収容部の一部の外から前記収容部の一部まで移動する請求項12に記載の磁気記録用磁性粉の分別装置。 - 前記収容部の一部にある分散液を排出する排出部をさらに備える請求項14に記載の磁気記録用磁性粉の分別装置。
- 前記収容部は、少なくとも第1室と第2室とを有し、
前記移動部は、前記磁場の印加位置を前記第1室から前記第2室に移動する請求項12に記載の磁気記録用磁性粉の分別装置。 - 前記磁場印加部は、前記移動に伴って前記磁場の印加位置が前記収容部の一端部から他端部に移動するように、前記移動の方向に対して斜めに保持されている請求項13に記載の磁気記録用磁性粉の分別装置。
- 前記収容部は、直方体状または円筒状を有する請求項12に記載の磁気記録用磁性粉の分別装置。
- 磁気記録用磁性粉が分散された液体に磁場を印加し、
前記液体に対する磁場の印加位置を相対的に移動し、
前記液体のうち、前記移動後の磁場の印加位置にある液体を取り、
取られた前記液体に含まれる磁気記録用磁性粉を用いて磁性層を形成する
ことを含む磁気記録媒体の製造方法。
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