WO2016166931A1 - 磁気記録媒体 - Google Patents
磁気記録媒体 Download PDFInfo
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- WO2016166931A1 WO2016166931A1 PCT/JP2016/001263 JP2016001263W WO2016166931A1 WO 2016166931 A1 WO2016166931 A1 WO 2016166931A1 JP 2016001263 W JP2016001263 W JP 2016001263W WO 2016166931 A1 WO2016166931 A1 WO 2016166931A1
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- particle powder
- metal
- recording medium
- mass
- magnetic recording
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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
- G11B5/733—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 characterised by the addition of non-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
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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
- G11B5/733—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 characterised by the addition of non-magnetic particles
- G11B5/7334—Base layer characterised by composition or structure
Definitions
- This technology relates to a magnetic recording medium.
- the present invention relates to a magnetic recording medium including a support, an underlayer, and a recording layer.
- a coating type magnetic recording medium formed by applying a paint on a nonmagnetic support and drying it is known.
- Such a coating-type magnetic recording medium is widely used as a high-density recording medium such as a backup data cartridge.
- Patent Document 1 proposes a magnetic recording medium that has excellent running durability, suppresses an increase in error rate under a low humidity environment, and has excellent electromagnetic conversion characteristics.
- This document also describes a technique for obtaining the indentation hardness (DH) of the surface of the magnetic layer by using a Barkovich indenter and setting the indentation hardness (DH) to 25 to 80 kg / mm 2 (245 to 785 MPa). ing.
- An object of the present technology is to provide a magnetic recording medium capable of improving running durability in a high humidity environment.
- the present technology includes a support, a base layer containing carbon particle powder and metal-containing particle powder, and a recording layer, and the maximum indentation depth h is 85 ⁇ In the magnetic recording medium, h ⁇ 140, and the ratio d (permanent strain / elastic recovery) of permanent strain to elastic recovery is 0.95 ⁇ d ⁇ 1.25.
- the running durability of the magnetic recording medium in a high humidity environment can be improved.
- 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. 2A is a graph for explaining a measurement method using a nanoindenter.
- FIG. 2B is a schematic diagram for explaining a measurement method using a nanoindenter.
- 3A and 3B are cross-sectional TEM images for explaining how to obtain the volume ratio of the carbon particle powder and the metal-containing particle powder.
- 4A is a cross-sectional TEM image of the magnetic tape of Example 16.
- FIG. 4B is a cross-sectional TEM image of the magnetic tape of Comparative Example 3.
- a magnetic recording medium is a so-called coating-type perpendicular magnetic recording medium, and has a nonmagnetic support 11 and one main surface of the nonmagnetic support 11 as illustrated in FIG.
- a base layer 12 provided and a recording layer 13 provided on the base layer 12 are provided.
- the magnetic recording medium may further include a back coat layer 14 provided on the other main surface of the nonmagnetic support 11 as necessary.
- the magnetic recording medium may further include a protective layer and a lubricant layer provided on the recording layer 13 as necessary.
- the main surface on the recording layer 13 side is referred to as a recording surface 13S.
- the maximum indentation depth h of the recording surface 13S measured with the nano indenter is 85 ⁇ h ⁇ 140, and the ratio d (permanent strain / elastic recovery) of the permanent deformation to the elastic recovery of the recording surface 13S measured with the nano indenter. ) Is 0.95 ⁇ d ⁇ 1.25.
- the maximum indentation depth h and the ratio d of the permanent strain to the elastic recovery are in the above ranges, the running durability in a high humidity environment can be improved.
- FIG. 2A is a load unloading curve showing the displacement of the indenter when the load is continuously increased and the indenter is pushed into the recording surface 13S of the magnetic recording medium and the load is released when the load reaches 200 ⁇ N. is there.
- States (1) to (3) shown in FIG. 2B show states of the indenter 21 at points (1) to (3) shown in FIG. 2A, respectively.
- the nonmagnetic support 11 is, for example, a flexible belt-like film.
- the material of the nonmagnetic support 11 include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose butyrate, polyvinyl chloride, and polyvinylidene chloride. Vinyl resins, polycarbonates, polyimides, polyamideimides and other plastics, light metals such as aluminum alloys and titanium alloys, and ceramics such as alumina glass. Furthermore, in order to increase the mechanical strength, a thin film containing an oxide of Al or Cu may be provided on at least one of the main surfaces of the nonmagnetic support 11 containing a vinyl resin or the like.
- the underlayer 12 is a nonmagnetic layer containing nonmagnetic powder and a binder.
- the underlayer 12 may further contain various additives such as conductive particles, a lubricant, an abrasive, a curing agent, and a rust preventive as necessary.
- the average thickness of the foundation layer 12 is preferably 1000 nm to 1300 nm, more preferably 1050 nm to 1150 nm.
- the average thickness of the foundation layer 12 is determined as follows. First, a magnetic recording medium is cut out perpendicularly to the main surface, and the cross section is observed with a transmission electron microscope (TEM). Next, 10 points are selected at random from the observed TEM image, and the thickness of the underlayer 12 is measured at each point. Next, these measured values are simply averaged (arithmetic average) to determine the average thickness of the underlayer 12. Below, the measurement conditions of TEM are shown. Equipment: TEM (Hitachi, H9000NAR) Acceleration voltage: 300kV Magnification: 100,000 times
- the non-magnetic powder includes carbon particle powder and metal-containing particle powder.
- the carbon particle powder includes, for example, carbon black particles.
- the metal-containing particle powder includes, for example, one or more selected from the group consisting of metal particles, metal oxide particles, metal carbonate particles, metal sulfate particles, metal nitride particles, metal carbide particles, and metal sulfide particles. Yes. Specifically, for example, at least one selected from the group consisting of silica particles, titanium oxide particles, alumina particles, iron oxide particles, and calcium carbonate particles is included. It is preferable that the nonmagnetic powder contains iron oxide particles and carbon black particles. This is because the dispersibility in the layer is improved, the film quality is improved, and the surface smoothness can be improved.
- the iron oxide particles are, for example, hematite ( ⁇ -Fe 2 O 3 ).
- Examples of the shape of the nonmagnetic powder include various shapes such as a needle shape, a spherical shape, and a plate shape, but are not limited thereto.
- the volume ratio (A: B) of the carbon particle powder A and the metal-containing particle powder B in the foundation layer 12 is 73:27 to 83:17.
- the range of the said volume ratio shall contain the numerical value of an upper limit and a lower limit. If the volume ratio of the carbon particle powder A is less than the above range, the recording surface 13S is too hard and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140. On the other hand, if the volume ratio of the carbon particle powder A exceeds the above range, the recording surface 13S is too soft and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140.
- the area ratio (A: B) of the carbon particle powder A and the metal-containing particle powder B in the foundation layer 12 is 66:34 to 74:26.
- the range of the said area ratio shall contain the numerical value of an upper limit and a lower limit. If the area ratio of the carbon particle powder A is less than the above range, the recording surface 13S is too hard and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140. On the other hand, if the area ratio of the carbon particle powder A exceeds the above range, the recording surface 13S is too soft and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140.
- the area ratio (A: B) between the carbon particle powder A and the metal-containing particle powder B is determined as follows. First, a magnetic recording medium is cut out perpendicularly to the main surface, and the cross section is observed with a TEM to obtain a TEM image. Below, the measurement conditions of TEM are shown. Equipment: TEM (Hitachi, H9000NAR) Acceleration voltage: 300kV Magnification: 100,000 times
- the area ratio (A: B) of the carbon particle powder A and the metal-containing particle powder B is determined from the TEM image using TEM image analysis software (OLYMPUS®Soft®Imaging®Solutions®iTEM) as follows.
- TEM image analysis software OLEDUS®Soft®Imaging®Solutions®iTEM
- the carbon particle powder A and the metal-containing particle powder B included in the cut image The total area (number of pixels) is obtained.
- threshold values of the carbon particle powder A and the metal-containing particle powder B are set, and the image is binarized as shown in FIG. 3B. Thereby, the image of metal containing particle powder is extracted.
- the area (number of pixels) of the metal-containing particle powder B is determined from the binarized image.
- the “area of the metal-containing particle powder B (number of pixels)” is subtracted from the “total area (number of pixels) of the carbon particle powder A and the metal-containing particle powder B” obtained as described above to obtain carbon particles.
- the area (number of pixels) of the powder A is obtained.
- the area ratio (A: B) between the carbon particle powder A and the metal-containing particle powder B is thus determined.
- the volume ratio (A: B) between the carbon particle powder A and the metal-containing particle powder B is determined as follows. First, the area ratio (A: B) between the carbon particle powder A and the metal-containing particle powder B is determined as described above. Next, assuming that the carbon particle powder A and the metal-containing particle powder B are spherical, the volume ratio of the carbon particle powder A and the metal-containing particle powder B using the obtained area ratio (A: B) ( A: B) is obtained. Specifically, the volume ratio (A: B) is obtained by the following equation.
- S A area of carbon particle powder A
- S B area of metal-containing particle powder B
- V A volume of carbon particle powder A
- V B volume of metal-containing particle powder B
- 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.
- a polyisocyanate may be used in combination with the resin, and this may be cross-linked and cured.
- the polyisocyanate include toluene diisocyanate and adducts thereof, alkylene diisocyanate, and adducts thereof.
- the conductive particles fine particles containing carbon as a main component, for example, carbon black can be used.
- carbon black for example, Asahi # 15 or # 15HS manufactured by Asahi Carbon Co. can be used.
- Examples of the lubricant include esters of monobasic fatty acids having 10 to 24 carbon atoms and any of monohydric to hexahydric alcohols having 2 to 12 carbon atoms, mixed esters thereof, difatty acid esters, and trifatty acid esters. Can be used as appropriate.
- lubricants include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, butyl stearate, pentyl stearate, heptyl stearate, octyl stearate , Isooctyl stearate, octyl myristate, and the like.
- the content of the lubricant is 1 part by mass or more and 1.5 parts by mass or less with respect to 100 parts by mass of the total amount of the carbon particle powder and the metal-containing particle powder. preferable. If the lubricant content is less than 1 part by mass, the recording surface 13S is too hard, and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140. On the other hand, if the lubricant content exceeds 1.5 parts by mass, the recording surface 13S is too soft and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140.
- abrasive for example, ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, ⁇ carbide of 90% or more, silicon carbide, chromium oxide, cerium oxide, ⁇ -iron oxide, corundum, silicon nitride, titanium carbide, oxide Needle-like ⁇ obtained by dehydrating and annealing titanium, silicon dioxide, tin oxide, magnesium oxide, tungsten oxide, zirconium oxide, boron nitride, zinc oxide, calcium carbonate, calcium sulfate, barium sulfate, molybdenum disulfide, and magnetic iron oxide Iron oxide and, if necessary, surface-treated with aluminum and / or silica are used alone or in combination.
- the content of the abrasive is preferably 2 parts by mass or more and 4 parts by mass or less with respect to 100 parts by mass of the total amount of the carbon particle powder and the metal-containing particle powder. If the content of the abrasive is less than 2 parts by mass, the recording surface 13S is too soft, and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140. On the other hand, when the content of the abrasive exceeds 4 parts by mass, the recording surface 13S is too hard and the maximum indentation depth h may be out of the range of 85 ⁇ h ⁇ 140.
- the recording layer 13 is, for example, a perpendicular recording layer capable of short wavelength recording or ultrashort wave super recording.
- the recording layer 13 is a magnetic layer having magnetic anisotropy in the thickness direction of the recording layer 13. That is, the easy axis of magnetization of the recording layer 13 is oriented in the thickness direction of the recording layer 13.
- the average thickness of the recording layer 13 is preferably 30 nm to 100 nm, more preferably 50 nm to 70 nm.
- the average thickness of the recording layer 13 is determined in the same manner as the above-described method for determining the average thickness of the underlayer 12.
- the recording layer 13 is a magnetic layer containing, for example, magnetic powder and a binder.
- the recording layer 13 may further contain various additives such as conductive particles, a lubricant, an abrasive, a curing agent, and a rust preventive as necessary.
- Magnetic powder is cubic ferrite magnetic powder.
- magnetic powder composed of cubic ferrite magnetic particles is referred to as cubic ferrite magnetic powder.
- the magnetic recording medium has a high S / N ratio.
- a higher output tends to be obtained when the coercive force Hc is higher due to the influence of the demagnetizing field.
- the higher coercive force is excellent in thermal stability when microparticulated.
- the next generation magnetic recording medium preferably has a high coercive force Hc.
- cubic ferrite magnetic powder having a high possibility of developing a coercive force Hc higher than that of hexagonal barium ferrite magnetic powder is used.
- the cubic ferrite magnetic powder has a cubic shape or a substantially cubic shape.
- “cubic ferrite magnetic powder is 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 powder is 0.75 or more.
- a rectangular parallelepiped that is 1.25 or less. Since the cubic ferrite magnetic powder has a small unit cell size, it is advantageous from the viewpoint of ultrafine particles in the future.
- the cubic ferrite magnetic powder is dispersed in the recording layer 13.
- the easy magnetization axis of the cubic ferrite magnetic powder is oriented in the thickness direction of the recording layer 13 or substantially in the thickness direction of the recording layer 13. That is, the cubic ferrite magnetic powder is dispersed in the recording layer 13 so that the square surface thereof is perpendicular or almost perpendicular to the thickness direction of the recording layer 13.
- the contact area between the particles in the thickness direction of the medium can be reduced and aggregation of the particles can be suppressed as compared with the hexagonal barium ferrite magnetic powder. That is, the dispersibility of the magnetic powder can be enhanced.
- the square surface of the cubic ferrite magnetic powder is preferably exposed from the surface of the recording layer 13. Performing short wavelength recording on the square surface with a magnetic head is advantageous in terms of high density recording compared to performing short wavelength recording on the hexagonal surface of a hexagonal plate-like barium ferrite magnetic powder having the same volume. It is. From the viewpoint of high density recording, the surface of the recording layer 13 is preferably covered with a square surface of cubic ferrite magnetic powder.
- the cubic ferrite magnetic particles are so-called spinel ferrimagnetic particles.
- the cubic ferrite magnetic particles are iron oxide particles having cubic ferrite as a main phase.
- the cubic ferrite contains one or more selected from the group consisting of Co, Ni, Mn, Al, Cu and Zn.
- 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, for example, cubic ferrite has an average composition represented by the general formula MFe 2 O 4 .
- M is one or more metals selected from the group consisting of Co, Ni, Mn, Al, Cu and Zn.
- M is a combination of Co and one or more metals selected from the group consisting of Ni, Mn, Al, Cu and Zn.
- the average plate diameter (average particle size) of the cubic ferrite magnetic powder is preferably 14 nm or less, more preferably 10 nm or more and 14 nm or less.
- the average plate diameter exceeds 14 nm, the exposed area of particles on the medium surface increases, and the S / N ratio may decrease.
- the average plate diameter is less than 10 nm, it may be difficult to produce cubic ferrite magnetic powder.
- the average plate ratio (average aspect ratio (average plate diameter L AM / average plate thickness L BM )) of the cubic ferrite magnetic powder is preferably 0.75 or more and 1.25 or less. If the average plate ratio is out of this numerical range, the cubic ferrite magnetic powder does not have a cubic or almost cubic shape, and thus aggregation occurs, which may make short wavelength recording difficult.
- the binder, conductive particles, lubricant, and abrasive are the same as those of the above-described underlayer 12.
- the recording 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) and the like.
- the back coat layer 14 contains a binder, inorganic particles, and a lubricant.
- the back coat layer 14 may contain various additives such as a curing agent and an antistatic agent as necessary.
- the binder, inorganic particles, and lubricant are the same as those of the above-described underlayer 12.
- 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.
- a backcoat layer-forming coating material is prepared by kneading and dispersing a binder, inorganic particles, a lubricant, and the like in a solvent.
- 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 for 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 on one main surface of the nonmagnetic support 11 by applying a coating for forming the base layer on one main surface of the nonmagnetic support 11 and drying it.
- the recording layer 13 is formed on the underlayer 12 by applying a coating for forming the recording layer on the underlayer 12 and drying it.
- the cubic ferrite magnetic powder contained in the magnetic powder is magnetically oriented so that the easy axis of magnetization of the cubic ferrite magnetic powder is oriented in the thickness direction of the recording layer 13 or substantially the recording layer 13. It is preferable to direct in the thickness direction.
- the obtained wide magnetic recording medium is rewound around a large-diameter core, and a curing process is performed.
- a calendar process is performed on the wide magnetic recording medium, and then cut into a predetermined width. Thereby, the intended magnetic recording medium is obtained.
- the step of forming the backcoat layer 14 may be after the calendar process.
- the maximum indentation depth h of the recording surface 13S measured with the nanoindenter is 85 ⁇ h ⁇ 140.
- the ratio d (permanent strain / elastic recovery) of the permanent strain to the elastic recovery of the recording surface 13S measured with the nanoindenter is 0.95 ⁇ d ⁇ 1.25.
- the magnetic recording medium is a perpendicular magnetic recording medium
- the magnetic recording medium may be a horizontal magnetic recording medium.
- the magnetic powder is not limited to this example, and a perpendicular magnetic recording medium or horizontal magnetic recording medium is used. Those generally used in can be used.
- Specific examples of the magnetic powder include Fe-based and Fe-Co-based metal powders, barium ferrite, iron carbide, and iron oxide.
- the formation process of the underlayer 12 and the recording layer 13 is not limited to the above example.
- the coating for forming the under layer is applied to one main surface of the nonmagnetic support 11 to form a coating film, and the coating for forming the recording layer is applied on the coating film in a wet state. Then, the undercoat layer 12 and the recording layer 13 may be formed on one main surface of the nonmagnetic support 11 by drying both coating films.
- Examples 1 to 21, Comparative Examples 1 to 9 (Preparation process of recording layer forming paint) A recording layer-forming coating material was prepared as follows. First, the following raw materials were kneaded with an extruder to obtain a kneaded product.
- Vinyl chloride resin 27.8 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
- Polyisocyanate 4 parts by mass (trade name: Coronate L, manufactured by Nippon Polyurethane)
- Myristic acid 2 parts 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 paint for forming the underlayer was prepared as follows. First, the following raw materials were kneaded with an extruder to obtain a kneaded product.
- Acicular iron oxide powder 21-56 parts by mass (content is adjusted for each sample as shown in Table 1)
- Vinyl chloride resin 55.6 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
- Carbon black 44 to 79 parts by mass (content is adjusted for each sample as shown in Table 1)
- C410 E410 ⁇ -alumina (abrasive): 2.2 to 3.5 parts by mass (adjust the content for each sample as shown in Table 2)
- the volume ratio (A: B) of carbon black A and acicular iron oxide powder B is 68 as shown in Table 1. : Adjuste
- a paint for forming a backcoat layer was prepared as follows. The following raw materials were mixed in a stirring tank equipped with a disper and filtered to prepare a backcoat layer-forming coating material.
- 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
- a base layer and a recording layer were formed as follows. First, a coating for forming an underlayer is applied to one main surface of a nonmagnetic support, a thickness of 6.2 ⁇ m, and a strip-shaped PEN film, and dried to obtain an average on one main surface of the PEN film. An underlayer having a thickness of 0.8 ⁇ m to 1.3 ⁇ m (see Table 2) was formed. Next, a recording layer-forming coating material was applied on the underlayer and dried to form a recording layer having an average thickness of 70 nm on the underlayer. Note that the magnetic powder was magnetically oriented during drying.
- the obtained wide magnetic tape was calendered with a metal roll to smooth the recording layer surface.
- the wide magnetic tape was cut into a width of 1/2 inch (12.65 mm) to obtain a target magnetic tape.
- Bit error rate is 10 ⁇ 5.9 or less
- Bit error rate is more than 10 ⁇ 5.9 and less than 10 ⁇ 5.5
- Bit error rate is 10 ⁇ 5.5 or more
- “ ⁇ ” indicates that the evaluation result is very good.
- “ ⁇ ” indicates that the evaluation result is good, and “X” indicates that the evaluation result is bad.
- Tables 1 and 2 show the structures and evaluation results of the magnetic tapes of Examples 1 to 21 and Comparative Examples 1 to 9.
- the maximum indentation depth h of the recording surface measured with the nanoindenter is 85 ⁇ h ⁇ 140, and the ratio d (permanent) of the permanent deformation to the elastic recovery of the recording surface measured with the nanoindenter It can be seen that when the strain / elastic recovery is 0.95 ⁇ d ⁇ 1.25, running durability in a high humidity environment can be improved.
- the present technology can also employ the following configurations.
- a support An underlayer comprising carbon particle powder and metal-containing particle powder; With a recording layer, On the recording surface, the maximum indentation depth h is 85 ⁇ h ⁇ 140, and the ratio d of permanent strain to elastic recovery (permanent strain / elastic recovery) is 0.95 ⁇ d ⁇ 1.25. .
- the area ratio of the carbon particle powder A to the metal-containing particle powder B (the area of the carbon particle powder: the area of the metal-containing particle powder) is 66:34 to 74:26, as described in (1) or (2) Magnetic recording media.
- the underlayer further includes a lubricant, Any one of (1) to (6), wherein the content of the lubricant is 1 part by mass or more and 1.5 parts by mass or less with respect to 100 parts by mass of the total amount of the carbon particle powder and the metal-containing particle powder.
- the underlayer further includes an abrasive, Content of the said abrasive
- polishing agent is 2 to 4 mass parts in any one of (1) to (7) with respect to 100 mass parts of total amounts of the said carbon particle powder and the said metal containing particle powder. Magnetic recording media.
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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
4 変形例
本技術の一実施形態に係る磁気記録媒体は、いわゆる塗布型の垂直磁気記録媒体であり、図1に示すように、非磁性支持体11と、非磁性支持体11の一方の主面上に設けられた下地層12と、下地層12上に設けられた記録層13とを備える。磁気記録媒体が、必要に応じて、非磁性支持体11の他方の主面上に設けられたバックコート層14をさらに備えるようにしてもよい。また、磁気記録媒体が、必要に応じて、記録層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。以下では、磁気記録媒体の両主面のうち、記録層13側の主面を記録面13Sという。
非磁性支持体11は、例えば、可撓性を有する帯状のフィルムである。非磁性支持体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。さらには、機械的強度を高めるために、AlまたはCuの酸化物を含む薄膜が、ビニル系樹脂などを含む非磁性支持体11の主面のうち少なくとも一方に設けられていてもよい。
下地層12は、非磁性粉および結着剤を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、研磨剤、硬化剤および防錆剤などの各種添加剤をさらに含んでいてもよい。
以下に、TEMの測定条件を示す。
装置:TEM(日立製作所製、H9000NAR)
加速電圧:300kV
倍率:100000倍
以下に、TEMの測定条件を示す。
装置:TEM(日立製作所製、H9000NAR)
加速電圧:300kV
倍率:100000倍
VA:VB=(SA)3/2:(SB)3/2
但し、SA:炭素粒子粉Aの面積、SB:金属含有粒子粉Bの面積、VA:炭素粒子粉Aの体積、VB:金属含有粒子粉Bの体積
記録層13は、例えば、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。記録層13は、記録層13の厚さ方向に磁気異方性を有する磁性層である。すなわち、記録層13の磁化容易軸は、記録層13の厚さ方向に向いている。記録層13の平均厚さは、好ましくは30nm以上100nm以下、より好ましくは50nm以上70nm以下である。なお、記録層13の平均厚さは、上述の下地層12の平均厚さの求め方と同様にして求められる。
バックコート層14は、結着剤、無機粒子および潤滑剤を含んでいる。バックコート層14が、必要に応じて硬化剤および帯電防止剤などの各種添加剤を含んでいてもよい。結着剤、無機粒子および潤滑剤は、上述の下地層12と同様である。
(塗料の調整工程)
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。次に、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11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12を非磁性支持体11の一方の主面上に形成する。
次に、下地層12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13を下地層12上に形成する。なお、乾燥の際に、磁性粉に含まれる立方晶フェライト磁性粉を磁場配向させることにより、立方晶フェライト磁性粉の磁化容易軸を記録層13の厚さ方向に向けるか、もしくはほぼ記録層13の厚さ方向に向けることが好ましい。
次に、非磁性支持体11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14を非磁性支持体11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が得られる。
次に、得られた幅広の磁気記録媒体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が得られる。なお、バックコート層14を形成する工程は、カレンダー処理後であってもよい。
本技術の一実施形態に係る磁気記録媒体では、ナノインデンターで測定した記録面13Sの最大押し込み深さhが、85≦h≦140である。また、ナノインデンターで測定した記録面13Sの、弾性回復に対する永久歪みの比d(永久歪み/弾性回復)が、0.95≦d≦1.25である。これにより、高湿度環境下における走行耐久性を向上できる。
上述の一実施形態では、磁気記録媒体が垂直磁気記録媒体である場合を例として説明したが、磁気記録媒体が水平磁気記録媒体であってもよい。
(記録層形成用塗料の調製工程)
記録層形成用塗料を次のようにして調製した。まず、下記原料をエクストルーダで混練して混練物を得た。
CoNiフェライト結晶磁性粉:100質量部
(形状:ほぼ立方体形状、平均板径:11nm、平均板状比:0.95)
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%)
ポリイソシアネート:4質量部
(商品名:コロネートL、日本ポリウレタン社製)
ミリスチン酸:2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: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
下地層形成用塗料を次のようにして調製した。まず、下記原料をエクストルーダで混練して混練物を得た。
針状酸化鉄粉末:21~56質量部(表1に示すようにサンプル毎に含有量を調整)
(ヘマタイト(α-Fe2O3)、XG-250またはDB-65Y)
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:44~79質量部(表1に示すようにサンプル毎に含有量を調整)
(CABOT製 E410)
α-アルミナ(研磨剤):2.2~3.5質量部(表2に示すようにサンプル毎に含有量を調整)
但し、カーボンブラックと針状酸化鉄粉末との含有量を上記範囲で調整することで、カーボンブラックAと針状酸化鉄粉末Bとの体積比(A:B)を表1に示すように68:32~91:9の範囲内で調整した。また、カーボンブラックAと針状酸化鉄粉末Bとの面積比(A:B)を表1に示すように62:38~82:18の範囲内で調整した。
ポリウレタン系樹脂UR8200(東洋紡績製):18.5質量部
ポリイソシアネート:4質量部
(商品名:コロネートL、日本ポリウレタン社製)
ステアリン酸(潤滑剤):0.8~1.5質量部(表2に示すようにサンプル毎に含有量を調整)
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
バックコート層形成用塗料を次のようにして調製した。下記原料を、ディスパーを備えた攪拌タンクで混合を行い、フィルター処理を行うことで、バックコート層形成用塗料を調製した。
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
次に、下地層および記録層を次のようにして形成した。まず、非磁性支持体である、厚さ6.2μm、帯状のPENフィルムの一方の主面上に、下地層形成用塗料を塗布、乾燥させることにより、PENフィルムの一方の主面上に平均厚さ0.8μm~1.3μm(表2参照)の下地層を形成した。次に、下地層上に、記録層形成用塗料を塗布、乾燥させることにより、下地層上に平均厚さ70nmの記録層を形成した。なお、乾燥の際に、磁性粉を磁場配向させた。
次に、PENフィルムの他方の主面上に、バックコート層形成用塗料を塗布、乾燥させることにより、PENフィルムの他方の面上に平均厚さ0.6μmのバックコート層を形成した。これにより、幅広の磁気テープを得た。
次に、得られた幅広の磁気テープに対して、金属ロールによるカレンダー処理を行い、記録層表面を平滑化した。次に、幅広の磁気テープを1/2インチ(12.65mm)幅に裁断して、目的とする磁気テープを得た。
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。
実施例16、比較例3の磁気テープをその記録面に対して垂直に切り出し、その断面をTEMにより観察した。その結果を図4A、図4Bに示す。
ナノインデンター測定方法により、最大押し込み深さ、および弾性回復に対する永久歪みの比d(永久歪み/弾性回復)を求めた。その結果を表2に示す。
以下に、測定条件を示す。
[圧子]
材質:三角錐ダイヤモンド圧子(Berkovich)
稜角:142.3°
硬度測定機:Hysitron社 Triboscope/島津SPM9500J
[評価条件]
測定環境:23℃/50%RH
荷重範囲:0~200μN(測定時)
最大荷重:200μN(設定)
荷重分解能:0.01μN
押し込み方向:記録面に対して垂直
まず、マウンテンエンジニアリング社のテープ走行系システムを用いるとともに、1/2インチテープに市販のLTO(Linier Tape Open)ドライブの磁気ヘッドを用いて、記録信号を市販のLTO6相当の記録密度で記録した。その後、29℃絶対湿度80%の環境で、初期から600時間走行後の磁気テープのエラーレートを測定した。その結果を表2に示す。なお、表2には、ビットエラーレートのうち10の指数の値のみを示した。次に、測定したビットエラーレートに基づき、以下の基準で走行耐久性を判定した。
◎:ビットエラーレートが10-5.9以下
○:ビットエラーレートが10-5.9を超え10-5.5未満
×:ビットエラーレートが10-5.5以上
但し、“◎”印は、評価結果が非常に良好であることを示し、“○”印は、評価結果が良好であることを示し、“×”印は、評価結果が悪いことを示す。
(1)
支持体と、
炭素粒子粉および金属含有粒子粉を含む下地層と、
記録層と
を備え、
記録面において、最大押し込み深さhが、85≦h≦140であり、弾性回復に対する永久歪みの比d(永久歪み/弾性回復)が、0.95≦d≦1.25である磁気記録媒体。
(2)
上記炭素粒子粉と上記金属含有粒子粉との体積比(上記炭素粒子粉の体積:上記金属含有粒子粉の体積)が、73:27~83:17である(1)に記載の磁気記録媒体。
(3)
炭素粒子粉Aと金属含有粒子粉Bとの面積比(上記炭素粒子粉の面積:上記金属含有粒子粉の面積)は、66:34~74:26である(1)または(2)に記載の磁気記録媒体。
(4)
上記金属含有粒子粉が、金属酸化物粒子粉である(1)から(3)のいずれかに記載の磁気記録媒体。
(5)
上記金属含有粒子粉が、酸化鉄粒子粉である(1)から(3)のいずれかに記載の磁気記録媒体。
(6)
上記炭素粒子粉が、カーボンブラック粒子粉である(1)から(5)のいずれかに記載の磁気記録媒体。
(7)
上記下地層が、潤滑剤をさらに含み、
上記潤滑剤の含有量が、上記炭素粒子粉と上記金属含有粒子粉との合計量100質量部に対して1質量部以上1.5質量部以下である(1)から(6)のいずれかに記載の磁気記録媒体。
(8)
上記下地層が、研磨剤をさらに含み、
上記研磨剤の含有量が、上記炭素粒子粉と上記金属含有粒子粉との合計量100質量部に対して2質量部以上4質量部以下である(1)から(7)のいずれかに記載の磁気記録媒体。
12 下地層
13 記録層
13S 記録面
14 バックコート層
Claims (8)
- 支持体と、
炭素粒子粉および金属含有粒子粉を含む下地層と、
記録層と
を備え、
記録面において、最大押し込み深さhが、85≦h≦140であり、弾性回復に対する永久歪みの比d(永久歪み/弾性回復)が、0.95≦d≦1.25である磁気記録媒体。 - 上記炭素粒子粉と上記金属含有粒子粉との体積比(上記炭素粒子粉の体積:上記金属含有粒子粉の体積)が、73:27~83:17である請求項1に記載の磁気記録媒体。
- 上記炭素粒子粉と上記金属含有粒子粉との面積比(上記炭素粒子粉の面積:上記金属含有粒子粉の面積)は、66:34~74:26である請求項1に記載の磁気記録媒体。
- 上記金属含有粒子粉が、金属酸化物粒子粉である請求項1に記載の磁気記録媒体。
- 上記金属含有粒子粉が、酸化鉄粒子粉である請求項1に記載の磁気記録媒体。
- 上記炭素粒子粉が、カーボンブラック粒子粉である請求項1に記載の磁気記録媒体。
- 上記下地層が、潤滑剤をさらに含み、
上記潤滑剤の含有量が、上記炭素粒子粉と上記金属含有粒子粉との合計量100質量部に対して1質量部以上1.5質量部以下である請求項1に記載の磁気記録媒体。 - 上記下地層が、研磨剤をさらに含み、
上記研磨剤の含有量が、上記炭素粒子粉と上記金属含有粒子粉との合計量100質量部に対して2質量部以上4質量部以下である請求項1に記載の磁気記録媒体。
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2016
- 2016-03-08 WO PCT/JP2016/001263 patent/WO2016166931A1/ja active Application Filing
- 2016-03-08 JP JP2017512188A patent/JP6586995B2/ja active Active
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JP2002237023A (ja) * | 2001-02-07 | 2002-08-23 | Fuji Photo Film Co Ltd | 磁気記録媒体 |
JP2006260613A (ja) * | 2005-03-15 | 2006-09-28 | Tdk Corp | 磁気記録媒体 |
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JP7136273B2 (ja) | 2022-09-13 |
JP6760456B2 (ja) | 2020-09-23 |
JP2020191153A (ja) | 2020-11-26 |
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US20180114541A1 (en) | 2018-04-26 |
DE112016001708T5 (de) | 2017-12-28 |
JP6586995B2 (ja) | 2019-10-09 |
JP2021119553A (ja) | 2021-08-12 |
DE112016001708B4 (de) | 2023-06-15 |
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JP6888724B2 (ja) | 2021-06-16 |
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