WO2017125981A1 - 磁気記録媒体 - Google Patents
磁気記録媒体 Download PDFInfo
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- WO2017125981A1 WO2017125981A1 PCT/JP2016/005121 JP2016005121W WO2017125981A1 WO 2017125981 A1 WO2017125981 A1 WO 2017125981A1 JP 2016005121 W JP2016005121 W JP 2016005121W WO 2017125981 A1 WO2017125981 A1 WO 2017125981A1
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- magnetic
- squareness ratio
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Images
Classifications
-
- 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
- G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
- G11B5/65—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition
- G11B5/658—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent characterised by its composition containing oxygen, e.g. molecular oxygen or magnetic oxide
-
- 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
-
- 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
Definitions
- This technology relates to a magnetic recording medium.
- a magnetic recording medium one having a configuration in which a nonmagnetic layer and a magnetic layer are laminated on a long support is known.
- acicular magnetic powder such as ferromagnetic iron oxide, Co-modified ferromagnetic iron oxide, CrO 2 , and ferromagnetic alloy is widely used.
- the acicular magnetic powder is magnetized in the longitudinal direction when the magnetic layer is formed.
- Magnetic recording media using acicular magnetic powder require ultra-short wavelength recording (reducing the recording wavelength) in order to achieve a high recording density.
- the major axis of the magnetic powder is shortened, the coercive force of the acicular magnetic powder is lowered. This is because the expression of the coercive force of the acicular magnetic powder is caused by the shape of the acicular shape. Further, when short wavelength recording is performed, the self-demagnetization becomes large and there is a possibility that sufficient output cannot be obtained.
- hexagonal barium ferrite magnetic powder is used in place of acicular magnetic powder in recent magnetic recording media compatible with LTO6 (abbreviation of LTO: Linear Tape Open).
- LTO6 abbreviation of LTO: Linear Tape Open
- a road map for high-density recording which shifts from the longitudinal recording method of acicular magnetic powder to the perpendicular recording method of barium ferrite magnetic powder, has been drawn (for example, see Non-Patent Document 1).
- spinel-type ferrimagnetic powder containing Co, Ni and other divalent metals has been reported as a magnetic powder for realizing high-density recording (for example, Patent Documents). 1).
- An object of the present technology is to provide a magnetic recording medium having a high signal-noise ratio (SNR).
- the present technology includes a long base and a magnetic layer containing powder of cubic ferrite magnetic particles, and the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is
- the magnetic recording medium is 1.2 or more and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.15 or more.
- a magnetic recording medium having a high SNR can be provided.
- FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a magnetic recording medium according to an embodiment of the present technology.
- FIG. 2 is a graph showing the relationship between the dispersion time and the squareness ratio.
- FIG. 3A is a graph showing the magnetization curve in the longitudinal direction of the magnetic tapes of Example 1, Comparative Example 1, and Comparative Example 5.
- FIG. 3B is a graph showing magnetization curves in the perpendicular direction of the magnetic tapes of Example 1, Comparative Example 1, and Comparative Example 5.
- FIG. 4A is a graph showing DC erasure noise of the magnetic tapes of Example 1 and Comparative Example 1.
- FIG. 4B is a graph showing frequency characteristics of the magnetic tapes of Example 1 and Comparative Example 1.
- a magnetic recording medium is a so-called perpendicular magnetic recording medium, and as illustrated in FIG. 1, a long base 11 and a base layer provided on one main surface of the base 11. 12 and a magnetic layer 13 provided on the underlayer 12.
- the magnetic recording medium may further include a protective layer and a lubricant layer provided on the magnetic layer 13 as necessary. Moreover, you may make it further provide the backcoat layer provided on the other main surface of the base
- the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.2 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.15 or more.
- the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.28 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.26 or more.
- the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction means the difference when “the squareness ratio in the vertical direction” is subtracted from the “squareness ratio in the longitudinal direction”. If the sum of the squareness ratios is less than 1.2, noise tends to increase and output tends to decrease.
- the SNR tends to deteriorate. If the difference in squareness ratio is less than 0.15, the noise tends to increase and the output tends to decrease, as in the case where the sum of squareness ratios is less than 1.2. That is, the SNR tends to deteriorate.
- the upper limit value of the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is, for example, 1.36 or less.
- the upper limit value of the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is, for example, 0.29 or less.
- the substrate 11 is a long film having flexibility.
- the material of the substrate 11 include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose butyrate, and vinyl-based materials such as polyvinyl chloride and polyvinylidene chloride. Resins, plastics such as polycarbonate, polyimide, and polyamideimide, light metals such as aluminum alloy and titanium alloy, ceramics such as alumina glass, and the like can be used.
- a thin film containing Al or Cu oxide or the like may be provided on at least one main surface of the substrate 11.
- the magnetic layer 13 is a perpendicular recording layer capable of short wavelength recording or ultrashort wave super recording.
- the magnetic layer 13 contains magnetic powder and a binder.
- the magnetic layer 13 may further contain at least one additive selected from conductive particles, a lubricant, an abrasive, a curing agent, a rust preventive agent, and the like as necessary.
- the magnetic powder is a powder of cubic ferrite magnetic particles (hereinafter referred to as “cubic ferrite magnetic powder”).
- cubic ferrite magnetic powder By using cubic ferrite magnetic powder as magnetic powder, higher coercive force Hc can be obtained than when hexagonal barium ferrite magnetic powder or the like is used as magnetic powder.
- the cubic ferrite magnetic powder is oriented in the longitudinal direction of the substrate 11. By being oriented in the longitudinal direction in this way, the sum of squareness ratios can be 1.2 or more, and the difference in squareness ratios can be 0.15 or more.
- the cubic ferrite magnetic particles are spinel ferrimagnetic particles.
- the cubic ferrite magnetic particles are iron oxide particles having cubic ferrite as a main phase.
- the cubic ferrite preferably contains one or more selected from the group consisting of Co, Ni, Mn, Al, Cu and Zn. More preferably, the cubic ferrite contains at least Co, and further contains at least one selected from the group consisting of Ni, Mn, Al, Cu and Zn in addition to Co. More specifically, cubic ferrite has an average composition represented by the general formula MFe 2 O 4 .
- M is preferably one or more metals selected from the group consisting of Co, Ni, Mn, Al, Cu and Zn. M is more preferably a combination of Co and one or more metals selected from the group consisting of Ni, Mn, Al, Cu and Zn.
- the cubic ferrite magnetic particles have a cubic shape or a substantially cubic shape.
- “cubic ferrite magnetic particles are almost cubic” means that the average plate ratio (average aspect ratio (average plate diameter L AM / average plate thickness L BM )) of cubic ferrite magnetic particles is 0.75 or more.
- a rectangular parallelepiped that is 1.25 or less. Since cubic ferrite magnetic particles have a small unit cell size, they are advantageous from the viewpoint of ultrafine particles in the future.
- the average plate diameter (average particle size) of the cubic ferrite magnetic particles is preferably 14 nm or less, more preferably 10 nm or more and 14 nm or less.
- the average plate diameter is 14 nm or less, the exposed area of particles on the medium surface can be reduced, and the SNR can be further improved.
- the average plate diameter is 10 nm or more, the production of cubic ferrite magnetic powder becomes easy.
- the average plate diameter of the cubic ferrite magnetic particles is obtained as follows. First, the surface of the magnetic layer 13 is observed with an atomic force microscope (AFM), and the length L A of one side of a square surface of several hundred cubic ferrite magnetic particles included in the AFM image is determined. Obtained as the plate diameter. Then, simply mean a plate diameter of several hundred cubic ferrite magnetic particles and (arithmetic mean) to obtain an average plate diameter L AM.
- AFM atomic force microscope
- the average plate ratio (average aspect ratio (average plate diameter L AM / average plate thickness L BM )) of the cubic ferrite magnetic particles is preferably 0.75 or more and 1.25 or less.
- the cubic ferrite magnetic particles have a cubic shape or a substantially cubic shape, so that aggregation of the magnetic powder can be suppressed.
- the average plate ratio of the cubic ferrite magnetic particles is obtained as follows. First, as described above, obtaining an average plate diameter L AM cubic ferrite magnetic particles. Next, the cross section of the magnetic layer 13 is observed with a transmission electron microscope (TEM), and the side face width L B of the hundreds of cubic ferrite magnetic particles included in the TEM image, that is, the side face is configured. determining the length L B of the sides of the square-shaped surface that as plate thickness. Next, the plate thickness L B of several hundreds of cubic ferrite magnetic particles is simply averaged (arithmetic average) to obtain the average plate thickness L BM . Next, an average plate ratio (average plate diameter L AM / average plate thickness L BM ) is determined using the average plate diameter L AM and the average plate thickness L BM determined as described above.
- TEM transmission electron microscope
- the binder a resin having a structure in which a crosslinking reaction is imparted to a polyurethane resin, a vinyl chloride resin, or the like is preferable.
- the binder is not limited to these, and other resins may be appropriately blended depending on the physical properties required for the magnetic recording medium.
- the resin to be blended is not particularly limited as long as it is a resin generally used in a coating type magnetic recording medium.
- thermosetting resins or reactive resins examples include phenol resins, epoxy resins, urea resins, melamine resins, alkyd resins, silicone resins, polyamine resins, urea formaldehyde resins, and the like.
- Each binder described above is introduced with a polar functional group such as —SO 3 M, —OSO 3 M, —COOM, P ⁇ O (OM) 2 for the purpose of improving the dispersibility of the magnetic powder. It may be.
- M in the formula is a hydrogen atom or an alkali metal such as lithium, potassium, or sodium.
- examples of the polar functional group include a side chain type having terminal groups of —NR1R2 and —NR1R2R3 + X—, and a main chain type of> NR1R2 + X—.
- R1, R2, and R3 in the formula are hydrogen atoms or hydrocarbon groups
- X- is a halogen element ion such as fluorine, chlorine, bromine, or iodine, or an inorganic or organic ion.
- examples of the polar functional group include —OH, —SH, —CN, and an epoxy group.
- the magnetic layer 13 is made of aluminum oxide ( ⁇ , ⁇ or ⁇ alumina), chromium oxide, silicon oxide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, titanium oxide (non-magnetic reinforcing particles). Rutile type or anatase type titanium oxide) may be further contained.
- the underlayer 12 is a nonmagnetic layer containing nonmagnetic powder and a binder as main components.
- the underlayer 12 may further contain at least one additive selected from conductive particles, lubricants, curing agents, rust inhibitors, and the like as necessary.
- the nonmagnetic powder may be an inorganic substance or an organic substance.
- the nonmagnetic powder may be carbon black.
- Examples of the inorganic substance include metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, and metal sulfides.
- Examples of the shape of the nonmagnetic powder include various shapes such as a needle shape, a spherical shape, a cubic shape, and a plate shape, but are not limited thereto.
- the binder is the same as that of the magnetic layer 13 described above.
- a base layer-forming coating material is prepared by kneading and dispersing a nonmagnetic powder and a binder in a solvent.
- a magnetic layer-forming coating material is prepared by kneading and dispersing magnetic powder, a binder and the like in a solvent. At this time, the dispersion time is adjusted to sufficiently disperse the magnetic powder.
- the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction will be 1.2 or more even if the magnetic powder is magnetically oriented in the subsequent step, and the perpendicularity to the squareness ratio in the longitudinal direction will be There is a possibility that the difference in the squareness ratio of the directions will not be 0.15 or more.
- the following solvent, dispersing device and kneading device can be used.
- 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 singly or may be mixed as appropriate.
- 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 12 is formed by applying the base layer forming paint to one main surface of the substrate 11 and drying it.
- the magnetic layer 13 is formed on the underlayer 12 by applying a coating for forming the magnetic layer on the underlayer 12 and drying it. During drying, the cubic ferrite magnetic powder contained in the magnetic powder is magnetically oriented in the longitudinal direction of the substrate 11 by, for example, a solenoid coil.
- a protective layer and a lubricant layer may be formed on the magnetic layer 13, or a backcoat layer may be formed on the other main surface of the substrate 11.
- the substrate 11 on which the underlayer 12 and the magnetic layer 13 are formed is rewound around the large-diameter core, and a curing process is performed.
- the base body 11 on which the underlayer 12 and the magnetic layer 13 are formed is calendered and then cut into a predetermined width. In this way, a pancake cut to a predetermined width can be obtained.
- the magnetic layer 13 includes cubic ferrite magnetic powder, the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.2 or more, and the longitudinal direction The difference between the squareness ratio and the squareness ratio in the vertical direction is 0.15 or more.
- cubic ferrite magnetic powder is used as the magnetic powder, and the cubic ferrite magnetic powder is longitudinally oriented in the coating and drying process of the magnetic layer forming paint. Is magnetically oriented.
- the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction can be 1.2 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction can be 0.15 or more.
- Aluminum oxide powder 5 parts by mass ( ⁇ -Al 2 O 3 , average particle size 0.2 ⁇ m)
- Carbon black 2 parts by mass (trade name: Seast TA, manufactured by Tokai Carbon Co., Ltd.)
- Vinyl chloride resin 27.8 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
- n-butyl stearate 2 parts by mass
- Methyl ethyl ketone 121.3 parts by mass
- Toluene 121.3 parts by mass
- Cyclohexanone 60.7 parts by mass
- a third composition having the following composition was kneaded with an extruder. Then, the 3rd composition and the 4th composition of the following mixing
- Polyurethane resin UR8200 (manufactured by Toyobo): 18.5 parts by mass n-butyl stearate: 2 parts by mass Methyl ethyl ketone: 108.2 parts by mass Toluene: 108.2 parts by mass Cyclohexanone: 18.5 parts by mass
- an underlayer and a magnetic layer were formed on a polyethylene naphthalate film (PEN film) as a substrate as follows.
- PEN film polyethylene naphthalate film
- an underlayer was formed on the PEN film by applying and drying an underlayer-forming paint on a 6.2 ⁇ m thick PEN film.
- the magnetic layer was formed on the underlayer by applying and drying the magnetic layer-forming paint on the underlayer.
- the CoNiMnZn ferrite crystal magnetic powder was magnetically oriented in the longitudinal direction of the PEN film by a solenoid coil.
- the PEN film on which the underlayer and the magnetic layer were formed was calendered with a metal roll to smooth the surface of the magnetic layer.
- a coating having the following composition was applied to a thickness of 0.6 ⁇ m on the surface of the PEN film on the side opposite to the magnetic layer, and a drying treatment was performed.
- Carbon black (Asahi Co., Ltd., trade name: # 80): 100 parts by mass Polyester polyurethane: 100 parts by mass (Nippon Polyurethanes, trade name: N-2304) Methyl ethyl ketone: 500 parts by mass Toluene: 400 parts by mass Cyclohexanone: 100 parts by mass
- the PEN film on which the underlayer, the magnetic layer, and the backcoat layer were formed as described above was cut into a 1 ⁇ 2 inch (12.65 mm) width to obtain a magnetic tape.
- the first composition was kneaded with an extruder.
- the first composition and the second composition were added to a stirring tank equipped with a disper and premixed.
- the same composition as in Reference Example 1-1 was used.
- sand mill mixing was further performed, and a filter treatment was performed to obtain a mixture.
- the mixture was pre-dispersed for 9 hours by a bead mill disperser (first disperser) using a circulating operation method using 3 mm ⁇ zirconia beads.
- a final dispersion treatment was further performed on the mixture subjected to the dispersion treatment by a bead mill disperser (second disperser) using a circulating operation method using 0.1 mm ⁇ zirconia beads.
- the final dispersion process time by the second disperser was changed for each sample in the range of 1 to 8 hours, so that the dispersion state of the paint was different for each sample.
- the magnetic layer forming coating material was prepared.
- a magnetic tape was obtained in the same manner as in Reference Example 1-1 except for the process for preparing the magnetic layer forming paint.
- Fig. 2 shows the relationship between dispersion time and squareness ratio.
- the following can be seen from FIG.
- the magnetic tape Reference Examples 1-1 to 1-17
- Co-based spinel ferrimagnetic powder cubic ferrite magnetic powder
- the squareness ratio in the longitudinal direction of the magnetic tape tends to increase. This is because by increasing the dispersion time, particles in which a certain number of particles are present in a lump are loosened, and the easy magnetization axes of the individual particles are easily oriented in the magnetic field direction.
- a final dispersion treatment was further performed on the mixture subjected to the dispersion treatment by a bead mill disperser (second disperser) using a circulating operation method using 0.1 mm ⁇ zirconia beads.
- the dispersion time of the paint was adjusted by setting the time of the final dispersion treatment by the second disperser for each sample.
- the magnetic layer forming coating material was prepared.
- Vinyl chloride resin 27.8 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
- n-butyl stearate 2 parts by mass
- Methyl ethyl ketone 121.3 parts by mass
- Toluene 121.3 parts by mass
- Cyclohexanone 60.7 parts by mass
- a third composition having the following composition was kneaded with an extruder. Then, the 3rd composition and the 4th composition of the following mixing
- Polyurethane resin UR8200 (manufactured by Toyobo): 18.5 parts by mass n-butyl stearate: 2 parts by mass Methyl ethyl ketone: 108.2 parts by mass Toluene: 108.2 parts by mass Cyclohexanone: 18.5 parts by mass
- an underlayer and a magnetic layer were formed on the PEN film as a substrate as follows.
- an underlayer was formed on the PEN film by applying and drying an underlayer-forming paint on a 6.2 ⁇ m thick PEN film.
- the magnetic layer was formed on the underlayer by applying and drying the magnetic layer-forming paint on the underlayer.
- the CoNiMnZn ferrite crystal magnetic powder was magnetically oriented in the longitudinal direction of the PEN film by a solenoid coil. At this time, as shown in Table 1, the intensity of the magnetic field was set for each sample.
- the PEN film on which the underlayer and the magnetic layer were formed was calendered with a metal roll to smooth the surface of the magnetic layer.
- a coating having the following composition was applied to a thickness of 0.6 ⁇ m on the surface of the PEN film on the side opposite to the magnetic layer, and a drying treatment was performed.
- Carbon black (Asahi Co., Ltd., trade name: # 80): 100 parts by mass Polyester polyurethane: 100 parts by mass (Nippon Polyurethanes, trade name: N-2304) Methyl ethyl ketone: 500 parts by mass Toluene: 400 parts by mass Cyclohexanone: 100 parts by mass
- the PEN film on which the underlayer, the magnetic layer, and the backcoat layer were formed as described above was cut into a 1 ⁇ 2 inch (12.65 mm) width to obtain a magnetic tape.
- Example 6 to 9 In the first composition preparation step, instead of CoNiMnZn ferrite crystal magnetic powder, CoNiMn ferrite crystal magnetic powder (particle shape: almost cubic, average particle size (average plate diameter): 20 to 30 nm, average aspect ratio (average plate) (Shape ratio): 1 to 1.2). Further, as shown in Table 1, the dispersion time of the second disperser was set for each sample to adjust the dispersion state of the paint. Further, in the magnetic layer forming step, as shown in Table 1, the strength of the magnetic field was set for each sample. Except for this, a magnetic tape was obtained in the same manner as in Example 1.
- the CoNiMn ferrite crystal magnetic powder was not oriented without magnetic field orientation in the longitudinal direction of the PEN film. Further, as shown in Table 1, the dispersion time of the second disperser was set for each sample to adjust the dispersion state of the paint. Except for this, a magnetic tape was obtained in the same manner as in Example 6.
- FIG. 3A shows longitudinal magnetization curves of the magnetic tapes of Example 1, Comparative Example 1, and Comparative Example 5.
- FIG. 3B shows the perpendicular magnetization curves of the magnetic tapes of Example 1, Comparative Example 1, and Comparative Example 5.
- SNR DC erase noise and SNR were determined by running a magnetic tape with a commercially available Mountain Engineering LFF and performing recording and reproduction using a head for a linear tape drive.
- the recording wavelength was 280 kFCI (kilo Flux Changes per Inch).
- DC erasure noise was measured with a spectrum analyzer, and direct current erasure was performed by applying a magnetic field to the tape with a commercially available neodymium magnet.
- the DC erasure noise means noise generated when a magnetic tape that has been DC erased (demagnetized) is reproduced.
- FIG. 4A shows DC erasure noise of the magnetic tapes of Example 1 and Comparative Example 1.
- FIG. 4B shows frequency characteristics of the magnetic tapes of Example 1 and Comparative Example 1.
- DC erasing noise obtained by integration up to a linear recording density of 500 kFCI was evaluated according to the following criteria.
- the symbols “ ⁇ ”, “ ⁇ ”, and “ ⁇ ” mean “very low noise”, “low noise”, and “high noise” as evaluation results, respectively.
- at least the DC erasure noise needs to be 0.0015 mVrms or less. Therefore, 0.0015 mVrms was set as a criterion for determining low DC erasure noise.
- SNR is 17 dB or more.
- ⁇ SNR is 15 dB or more and less than 17 dB.
- X SNR is less than 15 dB.
- the symbols “ ⁇ ”, “ ⁇ ”, and “ ⁇ ” mean “very good SNR”, “good SNR”, and “bad SNR” as evaluation results, respectively. Since the minimum SNR required to establish the recording / reproducing system is generally said to be about 15 dB, 15 dB was determined as a good SNR criterion.
- Table 1 shows the evaluation results of the magnetic tapes of Examples 1 to 9 and Comparative Examples 1 to 6.
- Rs Squareness ratio
- Hc Coercive force
- Table 1 shows the following.
- the magnetic tape (Examples 1 to 9) in which Co-based spinel ferrimagnetic powder (cubic ferrite magnetic powder) is magnetically oriented in the longitudinal direction of the magnetic tape, the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.2 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.15 or more.
- the magnetic tape in which Co-based spinel ferrimagnetic powder is not oriented, the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction does not become 0.15 or more.
- the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction does not become 1.2 or more.
- the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction does not become 0.15 or more, and the squareness ratio in the longitudinal direction and the perpendicular direction. The sum of the squareness ratios does not exceed 1.2.
- a magnetic tape in which the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.2 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.15 or more (Example 1) In (9) to (9), the DC erasing noise is low and a good SNR can be obtained. On the other hand, in the magnetic tapes (Comparative Examples 1 to 4) in which the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is not more than 0.15, the DC erasure noise is large and a good SNR cannot be obtained.
- a magnetic tape (Comparative Example 6) in which the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is not 1.2 or more the DC erasure noise is large and a good SNR cannot be obtained.
- a magnetic tape in which the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.28 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.26 or more (Example 1, In 2, 6), the DC erasing noise is particularly low, and a very good SNR can be obtained.
- 3A and 3B show the following. It can be seen that the residual magnetization that affects the output can be changed by applying a magnetic field in the longitudinal direction of the elongated substrate in the magnetic layer forming step. Note that the residual magnetization can be adjusted by changing the applied magnetic field strength.
- a magnetic tape in which Co-based spinel ferrimagnetic powder is magnetically oriented in the longitudinal direction of the magnetic tape has lower DC erasure noise and higher output than a magnetic tape in which Co-based spinel ferrimagnetic powder is not oriented. Therefore, a good SNR can be obtained.
- the present technology can also employ the following configurations.
- a long substrate A magnetic layer containing powder of cubic ferrite magnetic particles, A magnetic recording medium in which the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.2 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.15 or more.
- the magnetic recording medium according to (2), wherein the cubic ferrite magnetic particles further include one or more selected from the group consisting of Ni, Mn, Al, Cu, and Zn.
- the sum of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 1.28 or more, and the difference between the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.26 or more (1) to (3)
- a magnetic recording medium according to any one of the above (5) The magnetic recording medium according to any one of (1) to (4), wherein the powder of the cubic ferrite magnetic particles is oriented in the longitudinal direction. (6) The magnetic recording medium according to any one of (1) to (5), wherein the cubic ferrite magnetic particles have a cubic shape or a substantially cubic shape. (7) The magnetic recording medium according to any one of (1) to (6), wherein the magnetic layer is a perpendicular recording layer.
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Abstract
Description
1 磁気記録媒体の構成
2 磁気記録媒体の製造方法
3 効果
[1 磁気記録媒体の構成]
本技術の一実施形態に係る磁気記録媒体は、いわゆる垂直磁気記録媒体であり、図1に示すように、長尺状の基体11と、基体11の一方の主面上に設けられた下地層12と、下地層12上に設けられた磁性層13とを備える。磁気記録媒体が、必要に応じて、磁性層13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。また、必要に応じて、基体11の他方の主面上に設けられたバックコート層をさらに備えるようにしてもよい。
基体11は、可撓性を有する長尺状のフィルムである。基体11の材料としては、例えば、ポリエチレンテレフタレートなどのポリエステル類、ポリエチレン、ポリプロピレンなどのポリオレフィン類、セルローストリアセテート、セルロースダイアセテート、セルロースブチレートなどのセルロース誘導体、ポリ塩化ビニル、ポリ塩化ビニリデンなどのビニル系樹脂、ポリカーボネート、ポリイミド、ポリアミドイミドなどのプラスチック、アルミニウム合金、チタン合金などの軽金属、アルミナガラスなどのセラミックなどを用いることができる。磁気記録媒体の機械的強度を高めるために、AlまたはCuの酸化物などを含む薄膜が基体11の少なくとも一方の主面に設けられていてもよい。
磁性層13は、短波長記録または超短波超記録が可能な垂直記録層である。磁性層13は、磁性粉および結着剤を含んでいる。磁性層13が、必要に応じて、導電性粒子、潤滑剤、研磨剤、硬化剤および防錆剤などのうちの少なくとも1種の添加剤をさらに含んでいてもよい。
下地層12は、非磁性粉および結着剤を主成分として含む非磁性層である。下地層12が、必要に応じて、導電性粒子、潤滑剤、硬化剤および防錆剤などのうちの少なくとも1種の添加剤をさらに含んでいてもよい。
次に、上述の構成を有す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、磁性層形成用塗料を調製する。この際、分散時間などを調整して、十分に磁性粉を分散させるようにする。分散が不十分であると、後工程にて磁性粉を磁場配向させても、長手方向の角形比と垂直方向の角型比の和が1.2以上となり、かつ長手方向の角形比と垂直方向の角型比の差が0.15以上とならなくなる虞がある。磁性層形成用塗料および下地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用いることができる。
本技術の一実施形態に係る磁気記録媒体では、磁性層13が立方晶フェライト磁性粉を含み、長手方向の角形比と垂直方向の角型比の和が1.2以上であり、かつ長手方向の角形比と垂直方向の角型比の差が0.15以上である。これにより、高いSNRを有し、短波長記録が可能な磁気記録媒体を得ることができる。
i 磁性層形成用塗料の分散時間と角型比との関係
ii 長手方向、垂直方向の角型比の和および差とSNRとの関係
[参考例1-1~1-9]
まず、下記配合の第1組成物をエクストルーダで混練した。次に、ディスパーを備えた攪拌タンクに、第1組成物と、下記配合の第2組成物を加えて予備混合を行った。その後、さらにサンドミル混合を行い、フィルター処理を行って混合物を得た。次に、0.3mmφのジルコニアビーズを用いた循環運転方式のビーズミル分散機(第1分散機)により、上記混合物に分散処理(予備分散処理のみ)を施した。なお、第1分散機による分散処理の時間を1~9時間の範囲でサンプル毎に変化させて、塗料の分散状態をサンプル毎に異なるものとした。以上により、磁性層形成用塗料が調製された。
CoNiMnZnフェライト結晶磁性粉:100質量部
(粒子形状:ほぼ立方体状、平均粒子サイズ(平均板径):21nm、平均アスペクト比(平均板状比(平均板径/平均板厚)):1(=21nm/21nm)
塩化ビニル系樹脂(シクロヘキサノン溶液30質量%):55.6質量部
(重合度300、Mn=10000、極性基としてOSO3K=0.07mmol/g、2級OH=0.3mmol/gを含有する。)
酸化アルミニウム粉末:5質量部
(α-Al2O3、平均粒径0.2μm)
カーボンブラック:2質量部
(東海カーボン社製、商品名:シーストTA)
塩化ビニル系樹脂:27.8質量部
(樹脂溶液:樹脂分30質量%、シクロヘキサノン70質量%)
n-ブチルステアレート:2質量部
メチルエチルケトン:121.3質量部
トルエン:121.3質量部
シクロヘキサノン:60.7質量部
針状酸化鉄粉末:100質量部
(α-Fe2O3、平均長軸長0.15μm)
塩化ビニル系樹脂:55.6質量部
(樹脂溶液:樹脂分30質量%、シクロヘキサノン70質量%)
カーボンブラック:10質量部
(平均粒径20nm)
ポリウレタン系樹脂UR8200(東洋紡績製):18.5質量部
n-ブチルステアレート:2質量部
メチルエチルケトン:108.2質量部
トルエン:108.2質量部
シクロヘキサノン:18.5質量部
カーボンブラック(旭社製、商品名:#80):100質量部
ポリエステルポリウレタン:100質量部
(日本ポリウレタン社製、商品名:N-2304)
メチルエチルケトン:500質量部
トルエン:400質量部
シクロヘキサノン:100質量部
まず、第1組成物をエクストルーダで混練した。次に、ディスパーを備えた攪拌タンクに、第1組成物と、第2組成物を加えて予備混合を行った。なお、第1、第2組成物としては、参考例1-1と同様の配合のものを用いた。その後、さらにサンドミル混合を行い、フィルター処理を行って混合物を得た。次に、3mmφのジルコニアビーズを用いた循環運転方式のビーズミル分散機(第1分散機)により、上記混合物に予備分散処理を9時間施した。次に、0.1mmφのジルコニアビーズを用いた循環運転方式のビーズミル分散機(第2分散機)により、上記分散処理を施した混合物に最終分散処理をさらに施した。なお、第2分散機による最終分散処理の時間を1~8時間の範囲でサンプル毎に変化させて、塗料の分散状態をサンプル毎に異なるものとした。以上により、磁性層形成用塗料が調製された。
磁性層の形成工程において、CoNiMnZnフェライト結晶磁性粉をPENフィルムの長手方向に磁場配向させずに、無配向とする以外は参考例1-1~1-9と同様にして磁気テープを得た。
磁性層の形成工程において、CoNiMnZnフェライト結晶磁性粉をPENフィルムの長手方向に磁場配向させずに、無配向とする以外は参考例1-10~1-17と同様にして磁気テープを得た。
上述のようにして得られた磁気テープについて、以下の評価を行った。
振動試料型磁束計(Lakeshore社製)を用い、環境温度23~25℃、印加磁場15kOeで磁気テープの長手方向の磁化曲線を測定し、磁気テープの長手方向の角型比Rs(=Mr(無磁界での残留磁化)/Ms(15kOe時の磁化))を求めた。この際、ベースフィルム単体での磁化量の測定を行い、その磁化量を磁気テープの磁化量から引いてバックグランドの補正を行った。
[実施例1~5]
まず、下記配合の第1組成物をエクストルーダで混練した。その後、ディスパーを備えた攪拌タンクに、第1組成物と、下記配合の第2組成物を加えて予備混合を行った。その後、さらにサンドミル混合を行い、フィルター処理を行って混合物を得た。次に、3mmφのジルコニアビーズを用いた循環運転方式のビーズミル分散機(第1分散機)により、上記混合物に予備分散処理を9時間施した。次に、0.1mmφのジルコニアビーズを用いた循環運転方式のビーズミル分散機(第2分散機)により、上記分散処理を施した混合物に最終分散処理をさらに施した。なお、表1に示すように、第2分散機による最終分散処理の時間をサンプル毎に設定して、塗料の分散状態を調整した。以上により、磁性層形成用塗料が調製された。
CoNiMnZnフェライト結晶磁性粉:100質量部
(粒子形状:ほぼ立方体状、平均粒子サイズ(平均板径):20~30nm、平均アスペクト比(平均板状比(平均板径/平均板厚)):1.0~1.2)
塩化ビニル系樹脂(シクロヘキサノン溶液30質量%):55.6質量部
(重合度300、Mn=10000、極性基としてOSO3K=0.07mmol/g、2級OH=0.3mmol/gを含有する。)
酸化アルミニウム粉末:5質量部
(α-Al2O3、平均粒径0.2μm)
カーボンブラック:2質量部
(東海カーボン社製、商品名:シーストTA)
塩化ビニル系樹脂:27.8質量部
(樹脂溶液:樹脂分30質量%、シクロヘキサノン70質量%)
n-ブチルステアレート:2質量部
メチルエチルケトン:121.3質量部
トルエン:121.3質量部
シクロヘキサノン:60.7質量部
針状酸化鉄粉末:100質量部
(α-Fe2O3、平均長軸長0.15μm)
塩化ビニル系樹脂:55.6質量部
(樹脂溶液:樹脂分30質量%、シクロヘキサノン70質量%)
カーボンブラック:10質量部
(平均粒径20nm)
ポリウレタン系樹脂UR8200(東洋紡績製):18.5質量部
n-ブチルステアレート:2質量部
メチルエチルケトン:108.2質量部
トルエン:108.2質量部
シクロヘキサノン:18.5質量部
カーボンブラック(旭社製、商品名:#80):100質量部
ポリエステルポリウレタン:100質量部
(日本ポリウレタン社製、商品名:N-2304)
メチルエチルケトン:500質量部
トルエン:400質量部
シクロヘキサノン:100質量部
第1組成物の調製工程において、CoNiMnZnフェライト結晶磁性粉に代えて、CoNiMnフェライト結晶磁性粉(粒子形状:ほぼ立方体状、平均粒子サイズ(平均板径):20~30nm、平均アスペクト比(平均板状比):1~1.2)を用いた。また、表1に示すように、第2分散機の分散時間をサンプル毎に設定して、塗料の分散状態を調整した。更に、磁性層の形成工程において、表1に示すように、磁場の強度をサンプル毎に設定した。これ以外のことは、実施例1と同様にして磁気テープを得た。
磁性層の形成工程において、CoNiMnZnフェライト結晶磁性粉をPENフィルムの長手方向に磁場配向させずに、無配向とした。また、表1に示すように、第2分散機の分散時間をサンプル毎に設定して、塗料の分散状態を調整した。これ以外のことは、実施例1と同様にして磁気テープを得た。
磁性層の形成工程において、CoNiMnフェライト結晶磁性粉をPENフィルムの長手方向に磁場配向させずに、無配向とした。また、表1に示すように、第2分散機の分散時間をサンプル毎に設定して、塗料の分散状態を調整した。これ以外のことは、実施例6と同様にして磁気テープを得た。
第1組成物の調製工程において、CoNiMnZnフェライト磁性粉に代えて、針状を有するFeCo合金系メタル磁性粉を用いた。また、磁性層の形成工程において、FeCo合金系メタル磁性粉をPENフィルムの長手方向に10kOeで磁場配向させた。これ以外のことは、実施例1と同様にして磁気テープを得た。
第1組成物の調製工程において、CoNiMnZnフェライト磁性粉に代えて、六角板状を有するバリウムフェライト磁性粉を用いた。また、磁性層の形成工程において、磁場を加えずにバリウムフェライト磁性粉を自然にPENフィルムの厚さ方向に多少配向させた。これ以外のことは、実施例1と同様にして磁気テープを得た。
上述のようにして得られた磁気テープについて、以下の評価を行った。
振動試料型磁束計(Lakeshore社製)を用い、環境温度23~25℃、印加磁場15kOeで磁気テープの長手方向および磁気テープの表面に対して垂直方向の磁化曲線を測定し、長手方向および垂直方向の角型比Rs(=Mr(無磁界での残留磁化)/Ms(15kOe時の磁化))、垂直方向の保磁力Hcを求めた。この際、ベースフィルム単体での磁化量の測定を行い、その磁化量を磁気テープの磁化量から引いてバックグランドの補正を行った。次に、磁気テープの評価指標として、求めた長手方向および垂直方向の角型比から「長手方向の角形比と垂直方向の角型比の和」および「長手方向の角形比と垂直方向の角型比の差」を求めた。図3Aに、実施例1、比較例1、比較例5の磁気テープの長手方向の磁化曲線を示す。図3Bは、実施例1、比較例1、比較例5の磁気テープの垂直方向の磁化曲線を示す。
まず、市販のMountain Engineering社製のLFFで磁気テープを走行させ、リニアテープドライブ用のヘッドを用いて記録再生を行うことにより、DC消去ノイズおよびSNRを求めた。なお、記録波長は280kFCI(kilo Flux Changes per Inch)とした。DC消去ノイズの測定はスペクトラムアナライザーで行い、直流消去はテープに市販のネオジム磁石で磁場をかけることで行った。なお、DC消去ノイズは、直流消去(消磁)した磁気テープを再生した場合に発生するノイズを意味する。図4Aに、実施例1、比較例1の磁気テープの直流消去ノイズを示す。図4Bに、実施例1、比較例1の磁気テープの周波数特性を示す。
◎:DC消去ノイズが0.0012mVrms以下である。
○:DC消去ノイズが0.0012mVrmsを超え0.0015mVrms以下である。
×:DC消去ノイズが0.0015mVrmsを超える。
但し、SNRの評価において上記記号“◎”、“○”、“×”はそれぞれ、評価結果として“ノイズが非常に低い”、“ノイズが低い”、“ノイズが大きい”を意味する。記録再生システムを成立させるのに最低必要となるSNRを得るためには、少なくともDC消去ノイズを0.0015mVrms以下とする必要があるため、0.0015mVrmsを低いDC消去ノイズの判断基準とした。
◎:SNRが17dB以上である。
○:SNRが15dB以上17dB未満である。
×:SNRが15dB未満である。
但し、SNRの評価において上記記号“◎”、“○”、“×”はそれぞれ、評価結果として“SNRが非常に良好”、“SNRが良好”、“SNRが悪い”を意味する。記録再生システムを成立させるのに最低必要となるSNRは、一般に15dB程度といわれているため、15dBを良好なSNRの判断基準とした。
(1)
長尺状の基体と、
立方晶フェライト磁性粒子の粉末を含む磁性層と
を備え、
長手方向の角形比と垂直方向の角型比の和が1.2以上であり、かつ長手方向の角形比と垂直方向の角型比の差が0.15以上である磁気記録媒体。
(2)
上記立方晶フェライト磁性粒子は、Coを含んでいる(1)に記載の磁気記録媒体。
(3)
上記立方晶フェライト磁性粒子は、Ni、Mn、Al、CuおよびZnからなる群より選ばれる1種以上をさらに含んでいる(2)に記載の磁気記録媒体。
(4)
長手方向の角形比と垂直方向の角型比の和が1.28以上であり、長手方向の角形比と垂直方向の角型比の差が0.26以上である(1)から(3)のいずれかに記載の磁気記録媒体。
(5)
上記立方晶フェライト磁性粒子の粉末は、長手方向に配向している(1)から(4)のいずれかに記載の磁気記録媒体。
(6)
上記立方晶フェライト磁性粒子は、立方体状またはほぼ立方体状を有する(1)から(5)のいずれかに記載の磁気記録媒体。
(7)
上記磁性層は、垂直記録層である(1)から(6)のいずれかに記載の磁気記録媒体。
12 下地層
13 磁性層
Claims (7)
- 長尺状の基体と、
立方晶フェライト磁性粒子の粉末を含む磁性層と
を備え、
長手方向の角形比と垂直方向の角型比の和が1.2以上であり、かつ長手方向の角形比と垂直方向の角型比の差が0.15以上である磁気記録媒体。 - 上記立方晶フェライト磁性粒子は、Coを含んでいる請求項1に記載の磁気記録媒体。
- 上記立方晶フェライト磁性粒子は、Ni、Mn、Al、CuおよびZnからなる群より選ばれる1種以上をさらに含んでいる請求項2に記載の磁気記録媒体。
- 長手方向の角形比と垂直方向の角型比の和が1.28以上であり、長手方向の角形比と垂直方向の角型比の差が0.26以上である請求項1に記載の磁気記録媒体。
- 上記立方晶フェライト磁性粒子の粉末は、長手方向に配向している請求項1に記載の磁気記録媒体。
- 上記立方晶フェライト磁性粒子は、立方体状またはほぼ立方体状を有する請求項1に記載の磁気記録媒体。
- 上記磁性層は、垂直記録層である請求項1に記載の磁気記録媒体。
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PCT/JP2016/005121 WO2017125981A1 (ja) | 2016-01-20 | 2016-12-14 | 磁気記録媒体 |
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US (1) | US11355145B2 (ja) |
JP (1) | JP7073718B2 (ja) |
DE (1) | DE112016006261T5 (ja) |
WO (1) | WO2017125981A1 (ja) |
Cited By (1)
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JP2022091958A (ja) * | 2019-11-05 | 2022-06-21 | ソニーグループ株式会社 | 磁気記録媒体およびカートリッジ |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US11205455B2 (en) * | 2018-03-30 | 2021-12-21 | Sony Corporation | Magnetic recording medium |
JP2020043133A (ja) * | 2018-09-06 | 2020-03-19 | キオクシア株式会社 | 磁気記憶装置 |
KR20220131916A (ko) * | 2020-01-27 | 2022-09-29 | 파우더테크 컴퍼니 리미티드 | 페라이트 분말 및 그 제조 방법 |
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JPH05314457A (ja) * | 1992-05-13 | 1993-11-26 | Tdk Corp | 磁気記録媒体およびその製造方法 |
JP2007294084A (ja) * | 2006-03-31 | 2007-11-08 | Fujifilm Corp | 磁気記録媒体、磁気信号再生システムおよび磁気信号再生方法 |
JP2008243317A (ja) * | 2007-03-28 | 2008-10-09 | Fujifilm Corp | 磁気記録媒体及びその製造方法 |
WO2015198514A1 (ja) * | 2014-06-24 | 2015-12-30 | ソニー株式会社 | 磁気記録媒体 |
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JP3862088B2 (ja) | 2003-05-07 | 2006-12-27 | 学校法人明治大学 | スピネル型フェリ磁性粉及び磁気記録用媒体 |
JP4385216B2 (ja) * | 2003-11-27 | 2009-12-16 | 財団法人かがわ産業支援財団 | 六方晶フェライト微粒子分散流体の製造方法 |
US20090174969A1 (en) | 2006-03-31 | 2009-07-09 | Fujifilm Corporation | Magnetic recording medium, magnetic signal reproduction system and magnetic signal reproduction method |
AP2013007168A0 (en) * | 2011-03-15 | 2013-10-31 | Peerless Worldwide Llc | Facile synthesis of graphene, graphene derivativesand abrasive nanoparticles and their various uses , including as tribolofically-beneficial lubricantadditives |
-
2016
- 2016-12-14 WO PCT/JP2016/005121 patent/WO2017125981A1/ja active Application Filing
- 2016-12-14 DE DE112016006261.3T patent/DE112016006261T5/de not_active Withdrawn
- 2016-12-14 JP JP2017562161A patent/JP7073718B2/ja active Active
- 2016-12-14 US US16/070,140 patent/US11355145B2/en active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH05314457A (ja) * | 1992-05-13 | 1993-11-26 | Tdk Corp | 磁気記録媒体およびその製造方法 |
JP2007294084A (ja) * | 2006-03-31 | 2007-11-08 | Fujifilm Corp | 磁気記録媒体、磁気信号再生システムおよび磁気信号再生方法 |
JP2008243317A (ja) * | 2007-03-28 | 2008-10-09 | Fujifilm Corp | 磁気記録媒体及びその製造方法 |
WO2015198514A1 (ja) * | 2014-06-24 | 2015-12-30 | ソニー株式会社 | 磁気記録媒体 |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2022091958A (ja) * | 2019-11-05 | 2022-06-21 | ソニーグループ株式会社 | 磁気記録媒体およびカートリッジ |
JP7327561B2 (ja) | 2019-11-05 | 2023-08-16 | ソニーグループ株式会社 | 磁気記録媒体およびカートリッジ |
Also Published As
Publication number | Publication date |
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JP7073718B2 (ja) | 2022-05-24 |
US11355145B2 (en) | 2022-06-07 |
DE112016006261T5 (de) | 2018-10-04 |
US20190013043A1 (en) | 2019-01-10 |
JPWO2017125981A1 (ja) | 2018-11-15 |
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