WO2023100869A1 - Bande magnétique et corps d'enveloppement de bande magnétique - Google Patents

Bande magnétique et corps d'enveloppement de bande magnétique Download PDF

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Publication number
WO2023100869A1
WO2023100869A1 PCT/JP2022/043983 JP2022043983W WO2023100869A1 WO 2023100869 A1 WO2023100869 A1 WO 2023100869A1 JP 2022043983 W JP2022043983 W JP 2022043983W WO 2023100869 A1 WO2023100869 A1 WO 2023100869A1
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Prior art keywords
magnetic tape
magnetic
servo
recording
less
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PCT/JP2022/043983
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English (en)
Japanese (ja)
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成人 笠田
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富士フイルム株式会社
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Publication of WO2023100869A1 publication Critical patent/WO2023100869A1/fr

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
    • G11B15/18—Driving; Starting; Stopping; Arrangements for control or regulation thereof
    • G11B15/43—Control or regulation of mechanical tension of record carrier, e.g. tape tension
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/02—Containers; Storing means both adapted to cooperate with the recording or reproducing means
    • G11B23/04—Magazines; Cassettes for webs or filaments
    • G11B23/08—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends
    • G11B23/107—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends using one reel or core, one end of the record carrier coming out of the magazine or cassette
    • 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
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • 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
    • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/584—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes
    • 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
    • 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
    • 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
    • G11B5/735—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 back layer
    • 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
    • G11B5/74—Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
    • G11B5/78—Tape carriers

Definitions

  • the present invention relates to a magnetic tape and a magnetic tape container.
  • tape-shaped and disk-shaped magnetic recording media that is, magnetic tapes
  • tape-shaped magnetic recording media that is, magnetic tapes
  • Recording of data on a magnetic tape and reproduction of recorded data are usually performed by repeatedly pulling out a magnetic tape wound on one reel and winding it on the other reel between two reels. This is done while the tape is running in a magnetic recording/reproducing device (generally called a drive). Data is recorded and reproduced from the magnetic tape running in this way by a magnetic head in the drive.
  • a magnetic recording/reproducing device generally called a drive.
  • magnetic tape is generally said to have excellent cost performance due to the fact that the price per unit of data recorded is inexpensive and the power consumption during data storage is low. The greater the amount of data to be recorded, the higher the cost advantage. Therefore, in recent years, magnetic tapes have attracted attention as large-capacity data storage media. If the data transfer rate (write speed and/or read speed) is constant, the greater the amount of data to be recorded, the longer the time required to record the data and reproduce the recorded data. Therefore, in order to further increase the capacity of data recorded on magnetic tapes, it is desirable to increase the data transfer rate (write speed and/or read speed) of magnetic tapes.
  • a main object of one aspect of the present invention is to make it possible to improve the transfer rate in recording data on a magnetic tape and/or reproducing data recorded on a magnetic tape.
  • a magnetic tape having a non-magnetic support and a magnetic layer containing ferromagnetic powder A dimensional change ⁇ w in the width direction with respect to a change in tension in the longitudinal direction is 400 ppm/N or more and 900 ppm/N or less
  • the non-magnetic support is a polyethylene naphthalate support having a Young's modulus in the width direction of 10000 MPa or more
  • the coefficient of variation CV calculated by is 10% or less, .sigma.G is the standard deviation of the servo band spacing measured in an area over 100 m in the longitudinal direction of the magnetic tape under tension of 0.6 N in the longitudinal direction.
  • [5] The magnetic tape according to any one of [1] to [4], further comprising a nonmagnetic layer containing nonmagnetic powder between the nonmagnetic support and the magnetic layer.
  • [6] The magnetic field according to any one of [1] to [5], further comprising a back coat layer containing a non-magnetic powder on the surface side opposite to the surface side having the magnetic layer of the non-magnetic support. tape.
  • [7] The magnetic tape according to any one of [1] to [6], wherein the perpendicular squareness ratio of the magnetic tape is 0.60 or more.
  • a magnetic tape container including a core around which the magnetic tape according to any one of [1] to [7] is wound.
  • the roundness of the trajectory for one rotation drawn by the magnetic tape when pulling out the wound magnetic tape from the core is the arithmetic mean of the measured values at three points in the width direction of the magnetic tape. , 120 ⁇ m or less, the magnetic tape container according to any one of [8] to [12].
  • FIG. 1 is a perspective view of an example magnetic tape cartridge
  • FIG. FIG. 4 is a perspective view when starting to wind the magnetic tape around the reel
  • FIG. 4 is a perspective view when winding the magnetic tape around the reel is finished
  • 1 shows a schematic diagram of an example of a magnetic recording/reproducing device in which a magnetic tape cartridge is inserted
  • FIG. 1 shows a schematic diagram of an example of a magnetic recording/reproducing apparatus
  • FIG. FIG. 5 shows a schematic diagram of a state in which a magnetic tape cartridge having an opening formed in a case is mounted in the magnetic recording/reproducing apparatus shown in FIG. 4
  • An example arrangement of data bands and servo bands is shown.
  • An example of servo pattern arrangement for an LTO (Linear Tape-Open) Ultrium format tape is shown.
  • One aspect of the present invention relates to a magnetic tape having a non-magnetic support and a magnetic layer containing ferromagnetic powder.
  • the dimensional change amount ⁇ w in the width direction with respect to the tension change in the longitudinal direction of the magnetic tape is 400 ppm/N or more and 900 ppm/N or less.
  • the non-magnetic support is a polyethylene naphthalate support having a Young's modulus of 10000 MPa or more in the width direction.
  • the above ⁇ G is the standard deviation of the servo band spacing measured in an area over 100 m in the longitudinal direction of the magnetic tape under tension of 0.6 N in the longitudinal direction.
  • the magnetic head is normally built into the magnetic recording/reproducing apparatus, whereas the magnetic tape is treated as a removable medium (so-called exchangeable medium).
  • a magnetic tape cartridge containing a magnetic tape is inserted into a magnetic recording/reproducing device, and the magnetic tape is run between the reel of the magnetic tape cartridge and the take-up reel built into the magnetic recording/reproducing device. and/or reproduce data recorded on the magnetic tape.
  • the magnetic tape is housed in a magnetic tape cartridge and taken out from the magnetic recording/reproducing apparatus together with the magnetic tape cartridge.
  • the magnetic tape cartridge may be the magnetic tape container, and the winding core may be a reel provided in the magnetic tape cartridge.
  • the magnetic tape is not treated as a replaceable medium, but is housed in a magnetic recording/reproducing apparatus having a magnetic head.
  • the magnetic recording/reproducing device can be the magnetic tape container, and the core can be a reel provided in the magnetic recording/reproducing device. The configurations of the magnetic tape cartridge and the magnetic recording/reproducing device will be further described later.
  • ⁇ w is a value obtained by the method described in paragraphs 0093 to 0097 of Japanese Patent No. 6590102 (Patent Document 1).
  • ⁇ G in the present invention and this specification is a value determined by the following method.
  • the measurement is performed in an environment with an ambient temperature of 25° C. and a relative humidity of 50%.
  • a magnetic tape container housing a magnetic tape to be measured is placed in the same environment for 5 days or more in order to acclimatize to the measurement environment.
  • a magnetic recording/reproducing apparatus having a tension adjusting mechanism for applying tension in the longitudinal direction of the magnetic tape was subjected to a tension of 0.6 N in the longitudinal direction of the magnetic tape (tension set in the magnetic recording/reproducing apparatus). value) is applied and run the magnetic tape. If the magnetic tape container is a magnetic recording/reproducing device, the magnetic tape is run within this device.
  • the magnetic tape container is a magnetic tape cartridge
  • the magnetic tape cartridge is mounted on the magnetic recording/reproducing apparatus and the magnetic tape is run.
  • the magnetic tape was run under the above tension, and the interval between two adjacent servo bands sandwiching the data band was obtained for each 1 LPOS (Longitudinal Position) word. If there are a plurality of servo band intervals over the entire range in the longitudinal direction, the servo band intervals are found every 1 m for all LPOS words found for all servo band intervals. A region sandwiched between two adjacent servo bands is called a data band.
  • the number of servo band intervals is the same as the number of data bands.
  • the number of intervals between servo bands is also four.
  • the number of servo band intervals is "n”
  • ⁇ G the standard deviation ⁇ (that is, the positive square root of the variance) calculated using the measured values of the "100 ⁇ n” servo band intervals obtained in this way.
  • the interval between two adjacent servo bands sandwiching a data band can be obtained using, for example, PES (Position Error Signal) obtained from a servo signal obtained by reading a servo pattern with a servo signal reading element.
  • PES Position Error Signal
  • a tension of 0.6 N is used as an example of the tension that can be applied in the longitudinal direction of the magnetic tape running in the magnetic recording/reproducing apparatus.
  • a coefficient of variation CV is calculated from the following equation A using ⁇ w and ⁇ G obtained by the above method.
  • Formula A: CV ( ⁇ G/ ⁇ w) x 100
  • recording data on a magnetic tape and reproducing recorded data are usually performed between two reels by pulling out a magnetic tape wound on one reel and winding it on the other reel. This is done while the magnetic tape is running in the magnetic recording/reproducing apparatus by repeating the taking. More specifically, data is recorded on a magnetic tape by running the magnetic tape in a magnetic recording/reproducing apparatus and causing the magnetic head to follow the data band of the magnetic tape to record data on the data band. . A data track is thereby formed in the data band. When reproducing the recorded data, the magnetic tape is run in the magnetic recording/reproducing apparatus, and the magnetic head follows the data band of the magnetic tape to read the data recorded on the data band.
  • a system that performs head tracking using a servo signal (hereinafter referred to as a "servo system”) is in practical use. has been made Furthermore, by using the servo signal to acquire the dimension information of the running magnetic tape in the width direction, and adjusting the tension applied in the longitudinal direction of the magnetic tape according to the acquired dimension information, (as an example, see paragraph 0171 of Patent Document 1 (Japanese Patent No. 6590102)).
  • the magnetic head that records or plays back data shifts from the intended track position due to width deformation of the magnetic tape, resulting in problems such as overwriting of recorded data and poor playback.
  • transfer rate in recording data on the magnetic tape and/or reproducing data recorded on the magnetic tape.
  • transfer rate the transfer rate in recording data on the magnetic tape and/or reproducing data recorded on the magnetic tape.
  • transfer rate the transfer rate in recording data on the magnetic tape and/or reproducing data recorded on the magnetic tape.
  • the inventors of the present invention believe that suppressing the occurrence of the phenomenon described above by adjusting the tension described above would lead to an improvement in the transfer rate.
  • the inventors of the present invention believe that the occurrence of positional deviation in the width direction of the magnetic tape at a period shorter than the period at which the tension adjustment is performed when pulling out the wound magnetic tape is a cause of a decrease in the transfer rate. I assumed it could be.
  • the present inventors have found that such a positional deviation in the width direction of the magnetic tape in such a short period causes the magnetic recording/reproducing apparatus to temporarily stop the running of the magnetic tape, reverse the magnetic tape, and write or write data again. It was speculated that this could be the cause of increasing the frequency of "start/stop” or "repositioning” for reading. The more frequently the "start/stop” and/or “repositioning” are performed, the longer it takes to write data and/or read data, thus reducing the transfer rate. end up As a result of further intensive studies, the inventors of the present invention have come to believe that both ⁇ w and the coefficient of variation CV should be controlled in order to suppress the occurrence of positional deviation in the width direction at a short period.
  • the inventors of the present invention have found that by controlling ⁇ w and the coefficient of variation CV within the ranges described above, it is possible to improve the transfer rate in recording data on a magnetic tape and/or reproducing recorded data. newly found.
  • Patent Document 1 Japanese Patent No. 6590102
  • Japanese Patent No. 6590102 describes ⁇ w
  • the inventor believes that the small value of the coefficient of variation CV suppresses variations in dimensional changes in the width direction that occur when the magnetic tape runs under tension in the longitudinal direction. It is assumed that setting this value to 10% or less contributes to suppressing the occurrence of positional deviation in the width direction in the short period.
  • the present inventor believes that the magnetic tape includes a polyethylene naphthalate support having a Young's modulus in the width direction of 10000 MPa or more as a non-magnetic support, by adjusting the tension applied in the longitudinal direction of the magnetic tape. It is thought that it can contribute to enabling good recording and/or reproduction by controlling the dimension in the width direction.
  • the present invention is not limited to the speculations described herein, including the above speculations.
  • the magnetic tape and the magnetic tape container will be described in more detail below.
  • [Magnetic tape] ⁇ w> ⁇ w of the magnetic tape is 400 ppm/N or more and 900 ppm/N or less.
  • a magnetic tape with a large value of ⁇ w undergoes a large change in dimension in the width direction with respect to a change in tension in the longitudinal direction.
  • the magnetic head for recording or reproducing data may deviate from the target track position due to the width deformation of the magnetic tape, causing phenomena such as overwriting of recorded data and defective reproduction. This is preferable from the viewpoint of facilitating the suppression of the unfolding by adjusting the tension.
  • the ⁇ w of the magnetic tape is preferably 450 ppm/N or more, more preferably 500 ppm/N or more, still more preferably 550 ppm/N or more, and 600 ppm/N or more. is more preferred. Further, if the tension adjustment causes a large deformation in the width direction of the magnetic tape, it may cause an error. From the viewpoint of improving the transfer rate, it is preferable to be able to suppress the occurrence of such errors. From this point of view, ⁇ w of the magnetic tape is 900 ppm/N or less, preferably 850 ppm/N or less, more preferably 800 ppm/N or less, further preferably 750 ppm/N or less, and 700 ppm. /N or less is more preferable. A method of controlling ⁇ w will be described later.
  • the variation coefficient CV of the magnetic tape calculated by the above-described formula A is 10% or less, preferably 9% or less, 8% or less, 7% or less, 6% from the viewpoint of improving the transfer rate. 5% or less, 4% or less, 3% or less, 2% or less, and 1% or less, in that order.
  • the coefficient of variation CV can be, for example, 0%, 0% or more, 0% or more, or 1% or more. From the viewpoint of improving the transfer rate, the smaller the value of the coefficient of variation CV, the better. A method of controlling the coefficient of variation CV will be described later.
  • the magnetic tape includes a polyethylene naphthalate support having a Young's modulus in the width direction of 10000 MPa (megapascal) or more as a non-magnetic support (hereinafter also simply referred to as "support").
  • Polyethylene naphthalate is a resin containing a naphthalene ring and a plurality of ester bonds (that is, a polyester containing a naphthalene ring). It is a resin that can be obtained by subjecting a transesterification reaction and a polycondensation reaction to
  • polyethylene naphthalate has a structure having one or more other components (e.g., copolymer components, components introduced into terminals or side chains, etc.) in addition to the above components. is also included.
  • polyethylene naphthalate support means a support comprising at least one layer of polyethylene naphthalate film.
  • polyethylene naphthalate film refers to a film in which polyethylene naphthalate is the most abundant component on a mass basis among the components constituting this film.
  • the "polyethylene naphthalate support” in the present invention and the specification includes those in which all the resin films contained in this support are polyethylene naphthalate films, and those in which polyethylene naphthalate films and other resin films are included. is included.
  • Specific forms of the polyethylene naphthalate support include a single-layer polyethylene naphthalate film, a laminated film of two or more layers of polyethylene naphthalate films having the same constituents, and a laminate of two or more layers of polyethylene naphthalate films having different constituents.
  • Films laminated films containing one or more layers of polyethylene naphthalate films and one or more layers of resin films other than polyethylene naphthalate films, and the like can be mentioned.
  • An adhesive layer or the like may optionally be included between two adjacent layers in the laminated film.
  • the polyethylene naphthalate support may also optionally include a metal film and/or a metal oxide film formed by vapor deposition or the like on one or both surfaces.
  • the non-magnetic support can be a biaxially stretched film, and may be a film subjected to corona discharge, plasma treatment, easy adhesion treatment, heat treatment, or the like.
  • the Young's modulus of a non-magnetic support is a value measured by the following method in a measurement environment of 23° C. and 50% relative humidity.
  • the Young's modulus shown in the table below is a value determined by the following method using Tensilon manufactured by Toyo Baldwin Co., Ltd. as a universal tensile tester. A sample piece cut out from a non-magnetic support to be measured is pulled by a universal tensile tester under the conditions of a distance between chucks of 100 mm, a tensile speed of 10 mm/min and a chart speed of 500 mm/min.
  • the universal tensile tester for example, a commercially available universal tensile tester such as Tensilon manufactured by Toyo Baldwin Co., Ltd. or a universal tensile tester with a known configuration can be used.
  • the Young's modulus in the longitudinal direction and width direction of the sample piece is calculated from the tangent to the rising portion of the load-elongation curve thus obtained.
  • the longitudinal direction and width direction of the sample piece mean the longitudinal direction and width direction when this sample piece is included in the magnetic tape.
  • the longitudinal direction and width direction of the non-magnetic support are removed by the above method. Young's modulus can also be obtained.
  • the Young's modulus of the polyethylene naphthalate support in the width direction is 10000 MPa or more. This is the reason why the above-mentioned magnetic tape makes it possible to control the dimension of the magnetic tape in the width direction by adjusting the tension applied to the magnetic tape in the longitudinal direction and to perform good recording and/or reproduction.
  • the widthwise Young's modulus of the polyethylene naphthalate support may be, for example, 11000 MPa or more.
  • the widthwise Young's modulus of the polyethylene naphthalate support may be, for example, 20,000 MPa or less, 18,000 MPa or less, 16,000 MPa or less, or 14,000 MPa or less, or may exceed the values exemplified here.
  • the polyethylene naphthalate support may have a Young's modulus of 10000 MPa or more in the width direction, and the Young's modulus in the longitudinal direction is not particularly limited.
  • the longitudinal Young's modulus of the polyethylene naphthalate support is preferably 2500 MPa or more, more preferably 3000 MPa or more.
  • the longitudinal Young's modulus of the polyethylene naphthalate support may be, for example, 10000 MPa or less, 9000 MPa or less, 8000 MPa or less, 7000 MPa or less, or 6000 MPa or less. When the Young's modulus in the longitudinal direction of the non-magnetic support is large, ⁇ w tends to be small.
  • a non-magnetic support is generally used with the MD (machine direction) of the film as the longitudinal direction and the TD (transverse direction) as the width direction.
  • the Young's modulus in the longitudinal direction and the Young's modulus in the width direction of the non-magnetic support can be the same value in one form, and can be different values in another form. In one form, the Young's modulus in the width direction of the polyethylene naphthalate support may be larger than the Young's modulus in the longitudinal direction.
  • the Young's modulus of the non-magnetic support can be controlled by the types and mixing ratios of the components constituting the support, manufacturing conditions of the support, and the like.
  • the Young's modulus in the longitudinal direction and the Young's modulus in the width direction can be controlled by adjusting the draw ratio in each direction in the biaxial stretching process.
  • ferromagnetic powder As the ferromagnetic powder contained in the magnetic layer, one or a combination of two or more ferromagnetic powders known as ferromagnetic powders used in the magnetic layers of various magnetic recording media can be used. From the viewpoint of improving the recording density, it is preferable to use a ferromagnetic powder having a small average particle size. From this point of view, the average particle size of the ferromagnetic powder is preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less, even more preferably 35 nm or less, and 30 nm or less. It is even more preferably 25 nm or less, and even more preferably 20 nm or less.
  • the average particle size of the ferromagnetic powder is preferably 5 nm or more, more preferably 8 nm or more, still more preferably 10 nm or more, and 15 nm or more. is more preferable, and 20 nm or more is even more preferable.
  • Hexagonal Ferrite Powder A preferred specific example of the ferromagnetic powder is hexagonal ferrite powder.
  • hexagonal ferrite powder for details of the hexagonal ferrite powder, for example, paragraphs 0012 to 0030 of JP-A-2011-225417, paragraphs 0134-0136 of JP-A-2011-216149, paragraphs 0013-0030 of JP-A-2012-204726 and Paragraphs 0029 to 0084 of JP-A-2015-127985 can be referred to.
  • hexagonal ferrite powder refers to ferromagnetic powder in which the crystal structure of hexagonal ferrite is detected as the main phase by X-ray diffraction analysis.
  • the main phase refers to the structure to which the highest intensity diffraction peak is attributed in the X-ray diffraction spectrum obtained by X-ray diffraction analysis.
  • the highest intensity diffraction peak in an X-ray diffraction spectrum obtained by X-ray diffraction analysis is attributed to the crystal structure of hexagonal ferrite, it is determined that the crystal structure of hexagonal ferrite has been detected as the main phase. do.
  • the crystal structure of hexagonal ferrite contains at least iron atoms, divalent metal atoms and oxygen atoms as constituent atoms.
  • a divalent metal atom is a metal atom that can become a divalent cation as an ion, and examples thereof include alkaline earth metal atoms such as strontium, barium, and calcium atoms, and lead atoms.
  • hexagonal strontium ferrite powder means that the main divalent metal atoms contained in this powder are strontium atoms
  • hexagonal barium ferrite powder means that the main divalent metal atoms contained in this powder are a barium atom as a divalent metal atom.
  • the main divalent metal atom means the divalent metal atom that accounts for the largest amount on an atomic % basis among the divalent metal atoms contained in the powder.
  • the above divalent metal atoms do not include rare earth atoms.
  • "Rare earth atoms" in the present invention and herein are selected from the group consisting of scandium atoms (Sc), yttrium atoms (Y), and lanthanide atoms.
  • Lanthanide atoms include lanthanum atom (La), cerium atom (Ce), praseodymium atom (Pr), neodymium atom (Nd), promethium atom (Pm), samarium atom (Sm), europium atom (Eu), gadolinium atom (Gd ), terbium atom (Tb), dysprosium atom (Dy), holmium atom (Ho), erbium atom (Er), thulium atom (Tm), ytterbium atom (Yb), and lutetium atom (Lu) be.
  • La lanthanum atom
  • Ce cerium atom
  • Pr praseodymium atom
  • Nd neodymium atom
  • Pm promethium atom
  • Sm samarium atom
  • Eu europium atom
  • Gd gadolinium atom
  • Tb terbium atom
  • Dy dys
  • the hexagonal strontium ferrite powder which is one form of the hexagonal ferrite powder, will be described in more detail below.
  • the activated volume of the hexagonal strontium ferrite powder is preferably in the range of 800-1600 nm 3 .
  • a finely divided hexagonal strontium ferrite powder exhibiting an activation volume within the above range is suitable for making a magnetic tape exhibiting excellent electromagnetic conversion characteristics.
  • the activated volume of the hexagonal strontium ferrite powder is preferably greater than or equal to 800 nm 3 , for example it may be greater than or equal to 850 nm 3 .
  • the activated volume of the hexagonal strontium ferrite powder is more preferably 1500 nm 3 or less, further preferably 1400 nm 3 or less, and 1300 nm 3 or less. is more preferable, 1200 nm 3 or less is even more preferable, and 1100 nm 3 or less is even more preferable.
  • the same is true for the activation volume of hexagonal barium ferrite powder.
  • the "activation volume” is a unit of magnetization reversal, and is an index indicating the magnetic size of a particle.
  • the activation volume and the anisotropy constant Ku described in the present invention and this specification were measured using a vibrating sample magnetometer at magnetic field sweep speeds of 3 minutes and 30 minutes at the coercive force Hc measurement unit (measurement Temperature: 23° C. ⁇ 1° C.), which is a value obtained from the following relational expression between Hc and activation volume V.
  • Hc 2Ku/Ms ⁇ 1 ⁇ [(kT/KuV)ln(At/0.693)] 1/2 ⁇
  • Ku anisotropy constant (unit: J/m 3 )
  • Ms saturation magnetization (unit: kA/m)
  • k Boltzmann constant
  • T absolute temperature (unit: K)
  • V activity volume (unit: cm 3 )
  • A spin precession frequency (unit: s ⁇ 1 )
  • t magnetic field reversal time (unit: s)]
  • An anisotropic constant Ku can be cited as an index for reducing thermal fluctuation, in other words, improving thermal stability.
  • the hexagonal strontium ferrite powder can preferably have a Ku of 1.8 ⁇ 10 5 J/m 3 or more, more preferably 2.0 ⁇ 10 5 J/m 3 or more.
  • Ku of the hexagonal strontium ferrite powder can be, for example, 2.5 ⁇ 10 5 J/m 3 or less.
  • the higher the Ku value the higher the thermal stability, which is preferable.
  • the hexagonal strontium ferrite powder may or may not contain rare earth atoms.
  • the hexagonal strontium ferrite powder contains rare earth atoms, it preferably contains 0.5 to 5.0 atomic % of rare earth atoms (bulk content) with respect to 100 atomic % of iron atoms.
  • the hexagonal strontium ferrite powder containing rare earth atoms can have uneven distribution of rare earth atoms on the surface layer.
  • rare earth atom surface uneven distribution refers to the rare earth atom content ratio (hereinafter referred to as "Rare earth atom surface layer content” or simply “surface layer content” with respect to rare earth atoms) is based on 100 atomic% of iron atoms in the solution obtained by completely dissolving the hexagonal strontium ferrite powder with an acid rare earth atom content (hereinafter referred to as "rare earth atom bulk content” or simply “bulk content” with respect to rare earth atoms);
  • Rare earth atom surface layer content/rare earth atom bulk content>1.0 means that the ratio of The rare earth atom content rate of the hexagonal strontium ferrite powder described later is synonymous with the rare earth atom bulk content rate.
  • the content of rare earth atoms in the solution obtained by partial dissolution is It is the rare earth atom content rate in the surface layer of the particles.
  • the rare earth atom surface layer portion content ratio satisfies the ratio of "rare earth atom surface layer portion content/rare earth atom bulk content rate >1.0" means that the rare earth atoms in the surface layer portion of the particles constituting the hexagonal strontium ferrite powder It means that it is unevenly distributed (that is, it exists more than inside).
  • the term "surface layer portion” means a partial region extending from the surface toward the inside of a particle that constitutes the hexagonal strontium ferrite powder.
  • the rare earth atom content is preferably in the range of 0.5 to 5.0 atomic % with respect to 100 atomic % of iron atoms.
  • the fact that the rare earth atoms are contained in the bulk content in the above range and that the rare earth atoms are unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder contributes to suppressing the decrease in reproduction output during repeated reproduction. Conceivable. This is because the hexagonal strontium ferrite powder contains rare earth atoms with a bulk content within the above range, and the rare earth atoms are unevenly distributed in the surface layers of the particles constituting the hexagonal strontium ferrite powder.
  • hexagonal strontium ferrite powder which has rare earth atoms unevenly distributed in the surface layer, as the ferromagnetic powder for the magnetic layer contributes to suppressing abrasion of the magnetic layer surface due to sliding against the magnetic head.
  • hexagonal strontium ferrite powder having rare earth atoms unevenly distributed on the surface layer can contribute to the improvement of the running durability of the magnetic tape. This is because the uneven distribution of rare earth atoms on the surfaces of the particles that make up the hexagonal strontium ferrite powder improves the interaction between the particle surfaces and organic substances (e.g., binders and/or additives) contained in the magnetic layer.
  • the rare earth atom content is in the range of 0.5 to 4.5 atomic %. is more preferable, the range of 1.0 to 4.5 atomic % is more preferable, and the range of 1.5 to 4.5 atomic % is even more preferable.
  • the above bulk content is the content obtained by completely dissolving the hexagonal strontium ferrite powder.
  • the atomic content refers to the bulk content obtained by completely dissolving the hexagonal strontium ferrite powder.
  • the hexagonal strontium ferrite powder containing rare earth atoms may contain only one kind of rare earth atoms as rare earth atoms, or may contain two or more kinds of rare earth atoms. When two or more rare earth atoms are included, the bulk content is determined for the total of two or more rare earth atoms. This point also applies to the present invention and other components in this specification. That is, unless otherwise specified, only one component may be used, or two or more components may be used. When two or more are used, the content or content refers to the total of two or more.
  • the contained rare earth atoms may be any one or more rare earth atoms.
  • Preferred rare earth atoms from the viewpoint of further suppressing a decrease in reproduction output in repeated reproduction include neodymium atoms, samarium atoms, yttrium atoms and dysprosium atoms, with neodymium atoms, samarium atoms and yttrium atoms being more preferred, and neodymium atoms. Atoms are more preferred.
  • the rare earth atoms need only be unevenly distributed on the surface layer of the particles constituting the hexagonal strontium ferrite powder, and the degree of uneven distribution is not limited.
  • the surface layer content of rare earth atoms obtained by partially dissolving under the dissolving conditions described later and the rare earth elements obtained by completely dissolving under the dissolving conditions described later The ratio of atoms to the bulk content, "surface layer content/bulk content", is greater than 1.0 and can be 1.5 or more.
  • the "surface layer content/bulk content” is greater than 1.0, it means that the rare earth atoms are unevenly distributed in the surface layer (ie, more present than in the interior) in the particles constituting the hexagonal strontium ferrite powder. do.
  • the ratio between the surface layer content of rare earth atoms obtained by partial dissolution under the dissolution conditions described later and the bulk content of rare earth atoms obtained by complete dissolution under the dissolution conditions described later, "surface layer content/ The “bulk content” can be, for example, 10.0 or less, 9.0 or less, 8.0 or less, 7.0 or less, 6.0 or less, 5.0 or less, or 4.0 or less.
  • the rare earth atoms should be unevenly distributed in the surface layer portion of the particles constituting the hexagonal strontium ferrite powder.
  • "Ratio" is not limited to the exemplified upper or lower limits.
  • Partial dissolution and total dissolution of hexagonal strontium ferrite powder are described below.
  • sample powders for partial dissolution and total dissolution are taken from the same lot of powder.
  • part of the hexagonal strontium ferrite powder taken out from the magnetic layer is subjected to partial melting, and the other part is subjected to complete melting.
  • the hexagonal strontium ferrite powder can be extracted from the magnetic layer, for example, by the method described in paragraph 0032 of JP-A-2015-91747.
  • the partial dissolution means dissolution to such an extent that residual hexagonal strontium ferrite powder can be visually confirmed in the liquid at the end of dissolution.
  • a region of 10 to 20% by mass of the particles constituting the hexagonal strontium ferrite powder can be dissolved out of 100% by mass of the entire particles.
  • the above-mentioned complete dissolution means that the hexagonal strontium ferrite powder is dissolved to the point where no residue of the hexagonal strontium ferrite powder remains in the liquid at the end of dissolution.
  • the partial dissolution and the measurement of the surface layer content are performed, for example, by the following methods.
  • dissolution conditions such as the amount of sample powder described below are examples, and dissolution conditions that allow partial dissolution and complete dissolution can be arbitrarily adopted.
  • a container for example, a beaker
  • 10 mL of 1 mol/L hydrochloric acid is held on a hot plate with a set temperature of 70° C. for 1 hour.
  • the resulting solution is filtered through a 0.1 ⁇ m membrane filter.
  • Elemental analysis of the filtrate thus obtained is performed by an inductively coupled plasma (ICP) analyzer. In this way, the surface layer portion content of rare earth atoms relative to 100 atomic % of iron atoms can be obtained.
  • ICP inductively coupled plasma
  • the total content of all rare earth atoms is taken as the surface layer portion content.
  • This point also applies to the measurement of the bulk content.
  • the measurement of the total dissolution and bulk content is carried out, for example, by the following method.
  • a container for example, a beaker
  • sample powder containing 12 mg of sample powder and 10 mL of 4 mol/L hydrochloric acid is held on a hot plate with a set temperature of 80° C. for 3 hours. After that, the partial dissolution and the measurement of the surface layer portion content are carried out in the same manner as described above, and the bulk content with respect to 100 atom % of iron atoms can be obtained.
  • the ferromagnetic powder contained in the magnetic tape have a high mass magnetization ⁇ s.
  • hexagonal strontium ferrite powder containing rare earth atoms but not unevenly distributed in the surface layer of rare earth atoms tends to have a significantly lower ⁇ s than hexagonal strontium ferrite powder containing no rare earth atoms.
  • hexagonal strontium ferrite powder having rare earth atoms unevenly distributed in the surface layer is considered preferable in order to suppress such a large decrease in ⁇ s.
  • the ⁇ s of the hexagonal strontium ferrite powder can be 45 A ⁇ m 2 /kg or greater, and can also be 47 A ⁇ m 2 /kg or greater.
  • ⁇ s is preferably 80 A ⁇ m 2 /kg or less, more preferably 60 A ⁇ m 2 /kg or less.
  • the strontium atom content can be, for example, in the range of 2.0 to 15.0 atomic % with respect to 100 atomic % of iron atoms. .
  • the hexagonal strontium ferrite powder can have strontium atoms as the only divalent metal atoms contained in the powder.
  • the hexagonal strontium ferrite powder can also contain one or more other divalent metal atoms in addition to the strontium atoms. For example, it can contain barium atoms and/or calcium atoms.
  • the barium atom content and calcium atom content in the hexagonal strontium ferrite powder are, for example, 0.05 to 5 atoms per 100 atomic percent of iron atoms. can be in the range of .0 atomic %.
  • hexagonal strontium ferrite powder may have any crystal structure.
  • the crystal structure can be confirmed by X-ray diffraction analysis.
  • the hexagonal strontium ferrite powder can have a single crystal structure or two or more crystal structures detected by X-ray diffraction analysis.
  • a hexagonal strontium ferrite powder can be one in which only the M-type crystal structure is detected by X-ray diffraction analysis.
  • M-type hexagonal ferrite is represented by a composition formula of AFe 12 O 19 .
  • A represents a divalent metal atom
  • the hexagonal strontium ferrite powder is M-type, A is only a strontium atom (Sr), or if A contains a plurality of divalent metal atoms, , as described above, strontium atoms (Sr) account for the largest amount on an atomic % basis.
  • the divalent metal atom content of the hexagonal strontium ferrite powder is usually determined by the type of crystal structure of the hexagonal ferrite, and is not particularly limited. The same applies to the iron atom content and the oxygen atom content.
  • the hexagonal strontium ferrite powder contains at least iron atoms, strontium atoms and oxygen atoms, and may also contain rare earth atoms.
  • the hexagonal strontium ferrite powder may or may not contain atoms other than these atoms.
  • the hexagonal strontium ferrite powder may contain aluminum atoms (Al).
  • the content of aluminum atoms can be, for example, 0.5 to 10.0 atomic % with respect to 100 atomic % of iron atoms.
  • the hexagonal strontium ferrite powder contains iron atoms, strontium atoms, oxygen atoms and rare earth atoms, and the content of atoms other than these atoms is 100 iron atoms.
  • the hexagonal strontium ferrite powder may contain no atoms other than iron atoms, strontium atoms, oxygen atoms and rare earth atoms.
  • the content expressed in atomic % above is the content of each atom (unit: mass %) obtained by completely dissolving the hexagonal strontium ferrite powder, and converted to the value expressed in atomic % using the atomic weight of each atom. It is required by conversion.
  • the phrase "not containing" an atom means that the content of the atom is 0% by mass as measured by an ICP analyzer after being completely dissolved.
  • the detection limit of an ICP analyzer is usually 0.01 ppm (parts per million) or less on a mass basis.
  • the above-mentioned "does not contain” shall be used in the sense of containing in an amount below the detection limit of the ICP analyzer.
  • the hexagonal strontium ferrite powder in one form, can be free of bismuth atoms (Bi).
  • Metal powder Ferromagnetic metal powder is also a preferred specific example of the ferromagnetic powder.
  • paragraphs 0137 to 0141 of JP-A-2011-216149 and paragraphs 0009-0023 of JP-A-2005-251351 can be referred to.
  • ⁇ -iron oxide powder A preferred specific example of the ferromagnetic powder is ⁇ -iron oxide powder.
  • ⁇ -iron oxide powder means a ferromagnetic powder in which the crystal structure of ⁇ -iron oxide is detected as the main phase by X-ray diffraction analysis.
  • X-ray diffraction analysis For example, when the highest intensity diffraction peak in the X-ray diffraction spectrum obtained by X-ray diffraction analysis is attributed to the crystal structure of ⁇ -iron oxide, it is determined that the crystal structure of ⁇ -iron oxide has been detected as the main phase.
  • a method for producing ⁇ -iron oxide powder a method of producing from goethite, a reverse micelle method, and the like are known.
  • the activated volume of the ⁇ -iron oxide powder is preferably in the range of 300-1500 nm 3 .
  • a finely divided ⁇ -iron oxide powder exhibiting an activation volume in the above range is suitable for making a magnetic tape exhibiting excellent electromagnetic conversion properties.
  • the activated volume of the ⁇ -iron oxide powder is preferably greater than or equal to 300 nm 3 and may eg be greater than or equal to 500 nm 3 .
  • the activated volume of the ⁇ -iron oxide powder is more preferably 1400 nm 3 or less, further preferably 1300 nm 3 or less, and 1200 nm 3 or less. is more preferable, and 1100 nm 3 or less is even more preferable.
  • An anisotropic constant Ku can be cited as an index for reducing thermal fluctuation, in other words, improving thermal stability.
  • the ⁇ -iron oxide powder can preferably have a Ku of 3.0 ⁇ 10 4 J/m 3 or more, more preferably 8.0 ⁇ 10 4 J/m 3 or more.
  • Ku of the ⁇ -iron oxide powder can be, for example, 3.0 ⁇ 10 5 J/m 3 or less.
  • a higher Ku means a higher thermal stability, which is preferable, and thus is not limited to the values exemplified above.
  • the ferromagnetic powder contained in the magnetic tape have a high mass magnetization ⁇ s.
  • the ⁇ s of the ⁇ -iron oxide powder can be 8 A ⁇ m 2 /kg or greater, and can also be 12 A ⁇ m 2 /kg or greater.
  • ⁇ s of the ⁇ -iron oxide powder is preferably 40 A ⁇ m 2 /kg or less, more preferably 35 A ⁇ m 2 /kg or less, from the viewpoint of noise reduction.
  • the average particle size of various powders such as ferromagnetic powder is a value measured by the following method using a transmission electron microscope.
  • the powder is photographed using a transmission electron microscope at a magnification of 100,000 times, and a photograph of the particles constituting the powder is obtained by printing on photographic paper or displaying on a display at a total magnification of 500,000 times.
  • the particles of interest are selected from the photograph of the particles obtained, and the contours of the particles are traced with a digitizer to measure the size of the particles (primary particles).
  • Primary particles refer to individual particles without agglomeration. The above measurements are performed on 500 randomly selected particles.
  • the arithmetic mean of the particle sizes of the 500 particles thus obtained is taken as the average particle size of the powder.
  • the transmission electron microscope for example, Hitachi's H-9000 transmission electron microscope can be used.
  • the particle size can be measured using known image analysis software such as Carl Zeiss image analysis software KS-400. Unless otherwise specified, the average particle size shown in the examples below was measured using a transmission electron microscope H-9000 manufactured by Hitachi, and image analysis software KS-400 manufactured by Carl Zeiss as image analysis software. value.
  • powder means a collection of particles.
  • ferromagnetic powder means an aggregate of ferromagnetic particles.
  • the aggregation of a plurality of particles is not limited to the form in which the particles constituting the aggregation are in direct contact, but also includes the form in which binders, additives, etc., which will be described later, are interposed between the particles. be.
  • the term particles is sometimes used to describe powders.
  • the size of the particles constituting the powder is the shape of the particles observed in the above particle photographs.
  • particle size is the shape of the particles observed in the above particle photographs.
  • (1) In the case of needle-like, spindle-like, columnar (however, the height is greater than the maximum major diameter of the bottom surface), etc., the length of the major axis constituting the particle, that is, the major axis length,
  • (2) In the case of a plate-like or columnar shape (where the thickness or height is smaller than the maximum major diameter of the plate surface or bottom surface), it is expressed by the maximum major diameter of the plate surface or bottom surface
  • (3) If the particle is spherical, polyhedral, irregular, or the like, and the major axis of the particle cannot be specified from the shape, it is represented by the equivalent circle diameter.
  • the equivalent circle diameter is obtained by the circular projection method.
  • the average acicular ratio of the powder is obtained by measuring the length of the minor axis of the particles in the above measurement, that is, the minor axis length, and obtaining the value of (long axis length / minor axis length) of each particle. It refers to the arithmetic mean of the values obtained for the particles.
  • the minor axis length is the length of the minor axis constituting the particle in the case of (1) in the definition of the particle size, and the thickness or height in the case of (2).
  • (long axis length/short axis length) is regarded as 1 for convenience.
  • the average particle size is the average major axis length
  • the average particle size is Average plate diameter
  • the average particle size is the average diameter (also referred to as average particle size or average particle size).
  • the ferromagnetic powder content (filling rate) in the magnetic layer is preferably in the range of 50 to 90% by mass, more preferably in the range of 60 to 90% by mass, relative to the total mass of the magnetic layer.
  • a high filling rate of the ferromagnetic powder in the magnetic layer is preferable from the viewpoint of improving the recording density.
  • the magnetic tape may be a coated magnetic tape, and the magnetic layer may contain a binder.
  • a binder is one or more resins.
  • various resins commonly used as binders for coating-type magnetic recording media can be used.
  • binders include polyurethane resins, polyester resins, polyamide resins, vinyl chloride resins, acrylic resins obtained by copolymerizing styrene, acrylonitrile, methyl methacrylate, etc., cellulose resins such as nitrocellulose, epoxy resins, phenoxy resins, polyvinyl acetal,
  • a resin selected from polyvinyl alkylal resins such as polyvinyl butyral can be used singly, or a plurality of resins can be mixed and used.
  • polyurethane resins acrylic resins, cellulose resins, and vinyl chloride resins. These resins may be homopolymers or copolymers. These resins can also be used as binders in the non-magnetic layer and/or backcoat layer, which will be described later. Paragraphs 0028 to 0031 of JP-A-2010-24113 can be referred to for the above binders.
  • the weight-average molecular weight of the resin used as the binder can be, for example, 10,000 or more and 200,000 or less.
  • the binder can be used in an amount of, for example, 1.0 to 30.0 parts by mass with respect to 100.0 parts by mass of the ferromagnetic powder.
  • Curing agents can also be used with resins that can be used as binders.
  • the curing agent can be, in one form, a thermosetting compound which is a compound in which a curing reaction (crosslinking reaction) proceeds by heating, and in another form, a photocuring compound in which a curing reaction (crosslinking reaction) proceeds by light irradiation. can be a chemical compound.
  • the curing agent can be contained in the magnetic layer in a state where at least a portion of it reacts (crosslinks) with other components such as a binder as the curing reaction progresses during the process of forming the magnetic layer. In this respect, when the composition used for forming other layers contains a curing agent, the same applies to layers formed using this composition.
  • Preferred curing agents are thermosetting compounds, preferably polyisocyanates.
  • the curing agent is contained in the composition for forming the magnetic layer in an amount of, for example, 0 to 80.0 parts by weight per 100.0 parts by weight of the binder, and preferably 50.0 to 80.0 parts by weight from the viewpoint of improving the strength of the magnetic layer. Parts by weight amounts can be used.
  • the magnetic layer may optionally contain one or more additives.
  • additives include the curing agents described above.
  • Additives contained in the magnetic layer include nonmagnetic powders (e.g., inorganic powders, carbon black, etc.), lubricants, dispersants, dispersing aids, antifungal agents, antistatic agents, antioxidants, and the like. can be done.
  • nonmagnetic powders e.g., inorganic powders, carbon black, etc.
  • lubricants e.g., inorganic powders, carbon black, etc.
  • lubricants e.g., inorganic powders, carbon black, etc.
  • dispersants e.g., dispersants, dispersing aids, antifungal agents, antistatic agents, antioxidants, and the like.
  • a non-magnetic layer which will be described later, may contain a lubricant.
  • Paragraphs 0030, 0031, 0034 to 0036 of JP-A-2016-126817 can be referred to for lubricants that can be contained in the non-magnetic layer.
  • paragraphs 0061 and 0071 of JP-A-2012-133837 can be referred to.
  • a dispersant may be added to the non-magnetic layer forming composition. See paragraph 0061 of JP-A-2012-133837 for the dispersant that can be added to the composition for forming a non-magnetic layer.
  • the non-magnetic powder that can be contained in the magnetic layer includes a non-magnetic powder that can function as an abrasive, and a non-magnetic powder that can function as a protrusion-forming agent that forms moderately protruding protrusions on the surface of the magnetic layer. (for example, non-magnetic colloidal particles, etc.).
  • the average particle size of colloidal silica (silica colloidal particles) shown in the examples below is a value obtained by the method described as a method for measuring the average particle size in paragraph 0015 of JP-A-2011-048878. .
  • Additives can be appropriately selected from commercial products according to desired properties, or can be produced by known methods and used in any amount. Examples of additives that can be used to improve the dispersibility of the abrasive in the magnetic layer containing the abrasive include dispersants described in paragraphs 0012 to 0022 of JP-A-2013-131285.
  • the magnetic layer described above can be provided directly on the surface of the non-magnetic support or indirectly via the non-magnetic layer.
  • the magnetic tape may have a magnetic layer directly on the surface of the non-magnetic support, or may have a magnetic layer on the surface of the non-magnetic support via a non-magnetic layer containing non-magnetic powder.
  • the non-magnetic powder used in the non-magnetic layer may be inorganic powder or organic powder. Carbon black or the like can also be used. Examples of powders of inorganic substances include powders of metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, metal sulfides, and the like. These non-magnetic powders are commercially available and can be produced by known methods.
  • paragraphs 0146 to 0150 of Japanese Patent Application Laid-Open No. 2011-216149 can be referred to.
  • carbon black that can be used in the non-magnetic layer see paragraphs 0040 and 0041 of JP-A-2010-24113.
  • the nonmagnetic powder content (filling rate) in the nonmagnetic layer is preferably in the range of 50 to 90% by mass, more preferably in the range of 60 to 90% by mass, based on the total mass of the nonmagnetic layer. .
  • the inventor believes that reducing the variation in the thickness of the magnetic tape (differences in thickness depending on the position) will lead to a smaller value of the coefficient of variation CV.
  • One of the means for reducing the thickness variation of the magnetic tape is to increase the dispersibility of the non-magnetic powder in the non-magnetic layer.
  • the composition for forming the non-magnetic layer preferably contains a component (dispersant) capable of enhancing the dispersibility of the non-magnetic powder contained in the composition.
  • a component dispersant
  • a compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 below can be used.
  • the "alkylester anion” can also be called an "alkylcarboxylate anion”.
  • R represents an alkyl group having 7 or more carbon atoms or a fluorinated alkyl group having 7 or more carbon atoms
  • Z + represents an ammonium cation
  • two or more components capable of forming the compound having the salt structure can be used when preparing the composition for forming the non-magnetic layer.
  • at least a portion of these components can form a compound having the above salt structure during the preparation of the composition for forming a non-magnetic layer.
  • the groups described below may have a substituent or may be unsubstituted.
  • the “carbon number” of a group having a substituent means the number of carbon atoms not including the number of carbon atoms of the substituent unless otherwise specified.
  • substituents include, for example, alkyl groups (eg alkyl groups having 1 to 6 carbon atoms), hydroxy groups, alkoxy groups (eg alkoxy groups having 1 to 6 carbon atoms), halogen atoms (eg fluorine atom, chlorine atom, bromine atom, etc.), a cyano group, an amino group, a nitro group, an acyl group, a carboxy group, a salt of a carboxy group, a sulfonic acid group, a salt of a sulfonic acid group, and the like.
  • alkyl groups eg alkyl groups having 1 to 6 carbon atoms
  • alkoxy groups eg alkoxy groups having 1 to 6 carbon atoms
  • halogen atoms eg fluorine atom, chlorine atom, bromine atom, etc.
  • a cyano group an amino group, a nitro group, an acyl group, a carboxy group, a salt of a carboxy
  • R represents an alkyl group having 7 or more carbon atoms or a fluorinated alkyl group having 7 or more carbon atoms.
  • a fluorinated alkyl group has a structure in which some or all of the hydrogen atoms constituting the alkyl group are substituted with fluorine atoms.
  • the alkyl group or fluorinated alkyl group represented by R may have a linear structure, may have a branched structure, may be a cyclic alkyl group or fluorinated alkyl group, and has a linear structure. is preferred.
  • the alkyl group or fluorinated alkyl group represented by R may have a substituent or may be unsubstituted, and is preferably unsubstituted.
  • An alkyl group represented by R can be represented by, for example, C n H 2n+1 -.
  • n represents an integer of 7 or more.
  • the fluorinated alkyl group represented by R can have a structure in which, for example, some or all of the hydrogen atoms constituting the alkyl group represented by C n H 2n+1 - are substituted with fluorine atoms.
  • the number of carbon atoms in the alkyl group or fluorinated alkyl group represented by R is 7 or more, preferably 8 or more, more preferably 9 or more, further preferably 10 or more, and 11 or more. more preferably, 12 or more, and even more preferably 13 or more.
  • the number of carbon atoms in the alkyl group or fluorinated alkyl group represented by R is preferably 20 or less, more preferably 19 or less, and even more preferably 18 or less.
  • Z + represents an ammonium cation.
  • the ammonium cation specifically has the following structure.
  • "*" in formulas representing part of a compound represents the bonding position between the structure of that part and an adjacent atom.
  • the nitrogen cation N + of the ammonium cation and the oxygen anion O 2 ⁇ in formula 1 can form a salt bridging group to form the ammonium salt structure of the alkyl ester anion represented by formula 1.
  • the fact that the compound having the ammonium salt structure of the alkyl ester anion represented by Formula 1 is contained in the non-magnetic layer can be confirmed by X-ray photoelectron spectroscopy (ESCA) and infrared spectroscopy for the magnetic tape. (IR: Infrared Spectroscopy) or the like can be used for confirmation. It can also be confirmed by the same method that the backcoat layer, which will be described later, contains the compound having the ammonium salt structure of the alkyl ester anion represented by formula (1).
  • ESA X-ray photoelectron spectroscopy
  • IR Infrared Spectroscopy
  • an ammonium cation represented by Z + can be provided, for example, by a nitrogen atom of a nitrogen-containing polymer becoming a cation.
  • a nitrogen-containing polymer means a polymer containing nitrogen atoms.
  • the terms "polymer” and “polymer” are used in the sense of including homopolymers and copolymers.
  • a nitrogen atom can be contained as an atom constituting a main chain of a polymer in one form, and can be contained as an atom constituting a side chain of a polymer in one form.
  • Polyalkyleneimine is a ring-opening polymer of alkyleneimine, and is a polymer having a plurality of repeating units represented by formula 2 below.
  • the nitrogen atom N constituting the main chain in Formula 2 can become a nitrogen cation N + to provide an ammonium cation represented by Z + in Formula 1. and can form an ammonium salt structure with an alkyl ester anion, for example as follows.
  • R 1 and R 2 each independently represent a hydrogen atom or an alkyl group, and n1 represents an integer of 2 or more.
  • the alkyl group represented by R 1 or R 2 includes, for example, an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group. group, more preferably a methyl group.
  • the alkyl group represented by R 1 or R 2 is preferably an unsubstituted alkyl group.
  • the combination of R 1 and R 2 in Formula 2 includes a mode in which one is a hydrogen atom and the other is an alkyl group, a mode in which both are hydrogen atoms, and a mode in which both are alkyl groups (same or different alkyl groups). There is a form, preferably a form in which both are hydrogen atoms.
  • n1 in Formula 2 is 2 or more.
  • n1 in Formula 2 can be, for example, 10 or less, 8 or less, 6 or less, or 4 or less.
  • the polyalkyleneimine may be a homopolymer containing only the same structure as the repeating structure represented by Formula 2, or may be a copolymer containing two or more different structures as the repeating structure represented by Formula 2. .
  • the number average molecular weight of the polyalkyleneimine that can be used to form the compound having the ammonium salt structure of the alkyl ester anion represented by Formula 1 can be, for example, 200 or more, preferably 300 or more, It is more preferably 400 or more.
  • the number average molecular weight of the polyalkyleneimine may be, for example, 10,000 or less, preferably 5,000 or less, and more preferably 2,000 or less.
  • the average molecular weight (weight average molecular weight and number average molecular weight) is measured by gel permeation chromatography (GPC: Gel Permeation Chromatography) and refers to a value determined by standard polystyrene conversion. Unless otherwise specified, the average molecular weight shown in the examples below is a value obtained by converting the value measured under the following measurement conditions using GPC into standard polystyrene (polystyrene conversion value).
  • GPC device HLC-8220 (manufactured by Tosoh Corporation) Guard column: TSKguardcolumn Super HZM-H Column: TSKgel Super HZ 2000, TSKgel Super HZ 4000, TSKgel Super HZ-M (manufactured by Tosoh Corporation, 4.6 mm (inner diameter) ⁇ 15.0 cm, 3 types of columns connected in series)
  • Eluent Tetrahydrofuran (THF) containing stabilizer (2,6-di-t-butyl-4-methylphenol)
  • Eluent flow rate 0.35 mL/min
  • Polyallylamine is a polymer of allylamine and is a polymer having a plurality of repeating units represented by Formula 3 below.
  • the nitrogen atom N constituting the amino group of the side chain in Formula 3 can become a nitrogen cation N + to provide an ammonium cation represented by Z + in Formula 1. and can form an ammonium salt structure with an alkyl ester anion, for example as follows.
  • the weight average molecular weight of the polyallylamine that can be used to form the compound having the ammonium salt structure of the alkyl ester anion represented by Formula 1 can be, for example, 200 or more, preferably 1,000 or more. , 1,500 or more.
  • the weight average molecular weight of the polyallylamine may be, for example, 15,000 or less, preferably 10,000 or less, and more preferably 8,000 or less.
  • the compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 is a nitrogen-containing polymer and at least one fatty acid selected from the group consisting of fatty acids having 7 or more carbon atoms and fluorinated fatty acids having 7 or more carbon atoms.
  • the salt-forming nitrogen-containing polymer can be one or more nitrogen-containing polymers, such as nitrogen-containing polymers selected from the group consisting of polyalkyleneimines and polyallylamines.
  • Fatty acids that form salts can be one or more fatty acids selected from the group consisting of fatty acids having 7 or more carbon atoms and fluorinated fatty acids having 7 or more carbon atoms.
  • a fluorinated fatty acid has a structure in which some or all of the hydrogen atoms constituting the alkyl group bonded to the carboxyl group COOH in the fatty acid are substituted with fluorine atoms.
  • the salt formation reaction can proceed easily. Room temperature is, for example, about 20 to 25.degree.
  • one or more nitrogen-containing polymers and one or more of the above fatty acids are used as components of the composition for forming a non-magnetic layer, and these are mixed in the process of preparing the composition for forming a non-magnetic layer. , the salt-forming reaction can proceed.
  • one or more nitrogen-containing polymers and one or more fatty acids are mixed to form a salt before preparing the composition for forming a non-magnetic layer, and then the salt is added to the non-magnetic layer.
  • a composition for forming a non-magnetic layer can be prepared by using it as a component of the composition for forming.
  • fatty acids examples include fatty acids having an alkyl group described above as R in Formula 1 and fluorinated fatty acids having a fluorinated alkyl group described as R in Formula 1 above.
  • the mixing ratio of the nitrogen-containing polymer and the fatty acid used to form the compound having the ammonium salt structure of the alkyl ester anion represented by Formula 1 is 10:10 as a mass ratio of the nitrogen-containing polymer:the fatty acid. It is preferably from 90 to 90:10, more preferably from 20:80 to 85:15, even more preferably from 30:70 to 80:20.
  • the compound having an ammonium salt structure of the alkyl ester anion represented by Formula 1 is added in an amount of, for example, 1.0 to 20.0 parts per 100.0 parts by mass of the non-magnetic powder when the composition for forming the non-magnetic layer is prepared. 0 parts by weight can be used, and it is preferable to use 1.0 to 10.0 parts by weight.
  • 0.1 to 10.0 parts by mass of nitrogen-containing polymer can be used per 100.0 parts by mass of nonmagnetic powder, and 0.5 to 8.0 parts by mass. It is preferred to use 0 parts by weight of the nitrogen-containing polymer.
  • the above fatty acid can be used, for example, in an amount of 0.05 to 10.0 parts by mass, preferably 0.1 to 5.0 parts by mass, per 100.0 parts by mass of the non-magnetic powder.
  • the non-magnetic layer can contain a binder and can also contain additives.
  • Known techniques for nonmagnetic layers can be applied to other details such as binders and additives for the nonmagnetic layer.
  • the type and content of the binder, the type and content of the additive, etc. can be applied to known techniques relating to the magnetic layer.
  • non-magnetic layers include non-magnetic powders as well as substantially non-magnetic layers containing a small amount of ferromagnetic powders, for example as impurities or intentionally.
  • the substantially non-magnetic layer means that the residual magnetic flux density of this layer is 10 mT or less, the coercive force is 7.96 kA/m (100 Oe) or less, or the residual magnetic flux density is 10 mT or less. and a coercive force of 7.96 kA/m (100 Oe) or less.
  • the non-magnetic layer preferably has no residual magnetic flux density and no coercive force.
  • the magnetic tape may or may not have a back coat layer containing non-magnetic powder on the surface of the non-magnetic support opposite to the surface having the magnetic layer.
  • the non-magnetic powder for the back coat layer the above description of the non-magnetic powder for the non-magnetic layer can be referred to.
  • the content (filling rate) of the nonmagnetic powder in the backcoat layer is preferably in the range of 50 to 90% by mass, more preferably in the range of 60 to 90% by mass, relative to the total mass of the backcoat layer. more preferred.
  • the composition for forming the backcoat layer preferably contains a component (dispersant) capable of enhancing the dispersibility of the non-magnetic powder contained in the composition.
  • a component capable of enhancing the dispersibility of the non-magnetic powder contained in the composition.
  • a compound having an ammonium salt structure of the alkyl ester anion represented by Formula 1 above can be used.
  • the backcoat layer-forming composition containing such a compound reference can be made to the above description of the non-magnetic layer-forming composition.
  • the mixing ratio of the nitrogen-containing polymer and the fatty acid used to form the compound having the ammonium salt structure of the alkyl ester anion represented by Formula 1 is 10:10 as a mass ratio of the nitrogen-containing polymer:the fatty acid. It is preferably from 90 to 90:10, more preferably from 20:80 to 85:15, even more preferably from 30:70 to 80:20. Further, the compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 is added in an amount of, for example, 1.0 to 20.0 parts per 100.0 parts by mass of the non-magnetic powder when preparing the composition for forming the backcoat layer. 0 parts by weight can be used, and it is preferable to use 1.0 to 10.0 parts by weight.
  • 0.1 to 10.0 parts by mass of the nitrogen-containing polymer can be used per 100.0 parts by mass of the non-magnetic powder. It is preferred to use 0 parts by weight of the nitrogen-containing polymer.
  • the above fatty acid can be used, for example, in an amount of 0.05 to 10.0 parts by mass, preferably 0.1 to 5.0 parts by mass, per 100.0 parts by mass of the non-magnetic powder.
  • the backcoat layer can contain a binder and can also contain additives.
  • binders and additives for the backcoat layer known techniques for the backcoat layer can be applied, and known techniques for the formulation of the magnetic layer and/or the non-magnetic layer can also be applied. For example, paragraphs 0018 to 0020 of JP-A-2006-331625 and US Pat. .
  • the thickness (total thickness) of magnetic tapes As for the thickness (total thickness) of magnetic tapes, with the enormous increase in the amount of information in recent years, magnetic tapes are required to have a higher recording capacity (higher capacity). Means for increasing the capacity include reducing the thickness of the magnetic tape (hereinafter also referred to as "thinning") and increasing the length of the magnetic tape that can be accommodated per roll of the magnetic tape cartridge. From this point, the thickness (total thickness) of the magnetic tape is preferably 5.6 ⁇ m or less, more preferably 5.5 ⁇ m or less, more preferably 5.4 ⁇ m or less, and more preferably 5.3 ⁇ m. It is more preferably 5.2 ⁇ m or less, and even more preferably 5.2 ⁇ m or less. From the viewpoint of ease of handling, the thickness of the magnetic tape is preferably 3.0 ⁇ m or more, more preferably 3.5 ⁇ m or more. As for the thickness of the magnetic tape, the value of ⁇ w tends to increase as the thickness decreases.
  • the thickness (total thickness) of the magnetic tape can be measured by the following method. Ten tape samples (for example, 5 to 10 cm in length) are cut out from an arbitrary portion of the magnetic tape, these tape samples are overlapped, and the thickness is measured. The value (thickness per tape sample) obtained by dividing the measured thickness by 1/10 is taken as the tape thickness. The thickness measurement can be performed using a known measuring instrument capable of measuring thickness on the order of 0.1 ⁇ m.
  • the thickness of the nonmagnetic support can be, for example, 3.0 ⁇ m or more, and can be, for example, 5.0 ⁇ m or less, 4.8 ⁇ m or less, 4.6 ⁇ m or less, 4.4 ⁇ m or less, or 4.2 ⁇ m or less. can.
  • the thickness of the magnetic layer can be optimized depending on the saturation magnetization amount of the magnetic head to be used, the head gap length, the recording signal band, etc., and is generally 0.01 ⁇ m to 0.15 ⁇ m. , preferably 0.02 ⁇ m to 0.12 ⁇ m, more preferably 0.03 ⁇ m to 0.1 ⁇ m.
  • At least one magnetic layer is sufficient, and the magnetic layer may be separated into two or more layers having different magnetic properties, and a known multilayer magnetic layer structure can be applied.
  • the thickness of the magnetic layer when separated into two or more layers is the total thickness of these layers.
  • the thickness of the nonmagnetic layer is, for example, 0.1 to 1.5 ⁇ m, preferably 0.1 to 1.0 ⁇ m.
  • the thickness of the backcoat layer is preferably 0.9 ⁇ m or less, more preferably 0.1 to 0.7 ⁇ m.
  • Various thicknesses such as the thickness of the magnetic layer can be obtained by the following methods. After exposing a section of the magnetic tape in the thickness direction with an ion beam, the exposed section is observed with a scanning electron microscope or a transmission electron microscope. Various thicknesses can be determined as the arithmetic mean of the thicknesses determined at two arbitrary locations in cross-sectional observation. Alternatively, various thicknesses can be obtained as design thicknesses calculated from manufacturing conditions and the like.
  • the process of preparing a composition for forming a magnetic layer, non-magnetic layer or backcoat layer usually includes at least a kneading process, a dispersing process, and a mixing process provided before or after these processes as required. can be done. Each step may be divided into two or more stages.
  • the components used for preparing each layer-forming composition may be added at the beginning or in the middle of any step.
  • the solvent one or more of various solvents commonly used in the production of coating-type magnetic recording media can be used.
  • paragraph 0153 of JP-A-2011-216149 can be referred to.
  • individual components may be added in two or more steps.
  • the binder may be dividedly added in the kneading step, the dispersing step, and the mixing step for viscosity adjustment after dispersion.
  • known manufacturing techniques can be used in various steps.
  • the kneading step it is preferable to use a kneader having a strong kneading force such as an open kneader, a continuous kneader, a pressure kneader or an extruder. Details of the kneading process can be referred to JP-A-1-106338 and JP-A-1-79274.
  • a known disperser can be used.
  • Filtration may be performed by a known method at any stage of preparing each layer-forming composition. Filtration can be performed, for example, by filter filtration.
  • a filter used for filtration for example, a filter having a pore size of 0.01 to 3 ⁇ m (eg, glass fiber filter, polypropylene filter, etc.) can be used.
  • the magnetic layer can be formed by directly coating the magnetic layer-forming composition on the surface of the non-magnetic support, or by sequentially or simultaneously coating the magnetic layer-forming composition with the non-magnetic layer-forming composition.
  • the backcoat layer is formed by applying a composition for forming a backcoat layer to It can be formed by coating the surface. For details of coating for forming each layer, paragraph 0066 of JP-A-2010-231843 can be referred to.
  • the coating layer of the composition for forming the magnetic layer can be subjected to orientation treatment in the orientation zone while the coating layer is in a wet state.
  • Various known techniques including those described in paragraph 0052 of JP-A-2010-24113 can be applied to the alignment treatment.
  • the vertical alignment treatment can be performed by a known method such as a method using opposed magnets with different polarities.
  • the drying speed of the coating layer can be controlled by the temperature and air volume of the drying air and/or the conveying speed in the orientation zone.
  • the coated layer may be pre-dried before being conveyed to the orientation zone.
  • increasing the calendering conditions can help reduce the thickness variation of the magnetic tape. Reducing the thickness variation of the magnetic tape can lead to reducing the coefficient of variation CV.
  • Calender conditions include calender pressure, calender temperature (surface temperature of calender rolls), calender speed, and the like. As for the calender pressure and calender temperature, the greater these values, the stronger the calendering, and the slower the calendering speed, the stronger the calendering.
  • the calendar pressure linear pressure
  • the calender temperature (surface temperature of the calender rolls) can be, for example, in the range of 85-120°C, preferably in the range of 90-110°C.
  • the calendering speed can range, for example, from 50 to 300 m/min, preferably from 50 to 200 m/min.
  • the magnetic tape can be a magnetic tape manufactured through the following heat treatment. Performing the following heat treatment can contribute to reducing the value of the coefficient of variation CV. Further, when performing such a heat treatment, strengthening the heat treatment conditions (for example, increasing the heat treatment temperature) can contribute to reducing the value of the coefficient of variation CV.
  • the magnetic tape that has been slit and cut to a width determined according to the standard can be wound around the core member, and heat treatment can be performed in the wound state.
  • the heat treatment is performed while the magnetic tape is wound around a core member for heat treatment (hereinafter referred to as "heat treatment winding core"), and the magnetic tape after the heat treatment is wound on a reel of a magnetic tape cartridge.
  • a magnetic tape cartridge in which a magnetic tape is wound on a reel can be manufactured.
  • the core for heat treatment can be made of metal, resin, paper, or the like. From the viewpoint of suppressing the occurrence of winding failures such as spokes, the material of the core for heat treatment is preferably a material with high rigidity. From this point of view, the core for heat treatment is preferably made of metal or resin.
  • the bending elastic modulus of the material of the core for heat treatment is preferably 0.2 GPa or more, more preferably 0.3 GPa or more.
  • the bending elastic modulus of the material of the core for heat treatment is preferably 250 GPa or less.
  • the core for heat treatment can be a solid or hollow core member. In the case of a hollow shape, the thickness is preferably 2 mm or more from the viewpoint of maintaining rigidity.
  • the core for heat treatment may or may not have a flange.
  • a magnetic tape to be wound around the core for heat treatment a magnetic tape having a length longer than that to be finally accommodated in the magnetic tape cartridge (hereinafter referred to as "final product length") was prepared, and this magnetic tape was wound around the core for heat treatment.
  • the heat treatment is performed by placing in a heat treatment environment in a state.
  • the length of the magnetic tape wound around the heat-treating core is equal to or longer than the final product length, and from the viewpoint of ease of winding around the heat-treating core or the like, it is preferably "final product length + ⁇ ". This ⁇ is preferably 5 m or more from the viewpoint of ease of winding.
  • the tension at the time of winding onto the core for heat treatment is preferably 0.1 N (Newton) or more. From the viewpoint of suppressing the occurrence of excessive deformation, the tension during winding onto the core for heat treatment is preferably 1.5 N or less, more preferably 1.0 N or less.
  • the outer diameter of the core for heat treatment is preferably 20 mm or more, more preferably 40 mm or more, from the viewpoint of ease of winding and suppression of coiling (curling in the longitudinal direction). Further, the outer diameter of the core for heat treatment is preferably 100 mm or less, more preferably 90 mm or less.
  • the width of the core for heat treatment should be equal to or greater than the width of the magnetic tape to be wound around the core.
  • the magnetic tape and the heat-treating core are sufficiently cooled before the magnetic tape is removed in order to prevent unintended deformation of the tape during the removal operation.
  • the removed magnetic tape is first wound on another core (called a "temporary take-up core"), and then removed from the temporary take-up core to a magnetic tape cartridge reel (generally with an outer diameter of about 40 to 50 mm). ) to wind the magnetic tape.
  • a temporary take-up core another core
  • a magnetic tape cartridge reel generally with an outer diameter of about 40 to 50 mm.
  • the above description of the heat treatment core can be referred to.
  • the length of "+ ⁇ " may be cut at an arbitrary stage.
  • the final product length of the magnetic tape may be wound from the temporary take-up core onto the reel of the magnetic tape cartridge, and the remaining "+ ⁇ " length may be cut off.
  • the ⁇ is preferably 20 m or less.
  • the ambient temperature for heat treatment (hereinafter referred to as “heat treatment temperature”) is preferably 40° C. or higher, more preferably 50° C. or higher.
  • the heat treatment temperature is preferably 75° C. or lower, more preferably 70° C. or lower, and even more preferably 65° C. or lower.
  • the weight absolute humidity of the atmosphere in which the heat treatment is performed is preferably 0.1 g/kg Dry air or more, more preferably 1 g/kg Dry air or more. An atmosphere having a weight absolute humidity within the above range is preferable because it can be prepared without using a special device for reducing moisture.
  • the weight absolute humidity is preferably 70 g/kg dry air or less, more preferably 66 g/kg dry air or less, from the viewpoint of suppressing dew condensation and deterioration of workability.
  • the heat treatment time is preferably 0.3 hours or longer, more preferably 0.5 hours or longer. Moreover, the heat treatment time is preferably 48 hours or less from the viewpoint of production efficiency.
  • Formation of servo pattern can also be called “recording of servo signals.” Formation of the servo pattern will be described below.
  • a servo pattern is usually formed along the longitudinal direction of the magnetic tape.
  • Methods of control using servo signals include timing-based servo (TBS), amplitude servo, frequency servo, and the like.
  • a magnetic tape conforming to the LTO (Linear Tape-Open) standard adopts a timing-based servo system.
  • LTO tape Linear Tape-Open
  • a servo pattern is composed of a plurality of non-parallel pairs of magnetic stripes (also called “servo stripes”) arranged continuously in the longitudinal direction of the magnetic tape.
  • servo stripes also called “servo stripes”
  • the term "timing-based servo pattern” refers to a servo pattern that enables head tracking in a timing-based servo system servo system.
  • the reason why the servo pattern is composed of a pair of non-parallel magnetic stripes is to inform the servo signal reading element passing over the servo pattern of its passing position.
  • the pair of magnetic stripes are formed so that the interval between them changes continuously along the width direction of the magnetic tape. and the relative position of the servo signal reading element. This relative position information enables tracking of the data tracks. For this reason, a plurality of servo tracks are usually set on the servo pattern along the width direction of the magnetic tape.
  • a servo band is composed of servo patterns that are continuous in the longitudinal direction of the magnetic tape.
  • a plurality of servo bands are usually provided on the magnetic tape. For example, in LTO tape, the number is five.
  • a data band is an area sandwiched between two adjacent servo bands. The data band is composed of a plurality of data tracks, each data track corresponding to each servo track.
  • each servo band includes information indicating the number of the servo band ("servo band ID (identification)” or "UDIM (Unique Data Band Identification)”).
  • Method also called information
  • This servo band ID is recorded by shifting a specific one of a plurality of pairs of servo stripes in the servo band so that the position thereof is relatively displaced in the longitudinal direction of the magnetic tape. Specifically, the method of shifting a specific one of a plurality of pairs of servo stripes is changed for each servo band.
  • the recorded servo band ID is unique for each servo band, so that one servo band can be uniquely specified only by reading one servo band with a servo signal reading element.
  • a method for uniquely specifying a servo band there is also a method using a staggered method as shown in ECMA-319 (June 2001).
  • this staggered method groups of non-parallel pairs of magnetic stripes (servo stripes) arranged continuously in the longitudinal direction of the magnetic tape are recorded so as to be shifted in the longitudinal direction of the magnetic tape for each servo band. do. Since this combination of shifts between adjacent servo bands is unique for the entire magnetic tape, the servo band can be uniquely identified when reading the servo pattern with two servo signal reading elements. It is possible.
  • each servo band information indicating the position in the longitudinal direction of the magnetic tape (also called “LPOS (Longitudinal Position) information”) is also usually embedded as indicated in ECMA-319 (June 2001).
  • LPOS Longitudinal Position
  • this LPOS information is also recorded by shifting the positions of a pair of servo stripes in the longitudinal direction of the magnetic tape.
  • the same signal is recorded in each servo band in this LPOS information.
  • UDIM and LPOS information can also be embedded in the servo band.
  • the embedded information may be different for each servo band, such as UDIM information, or common to all servo bands, such as LPOS information.
  • a method of embedding information in the servo band it is possible to adopt a method other than the above.
  • a predetermined code may be recorded by thinning out a predetermined pair from a group of paired servo stripes.
  • the servo pattern forming head is called a servo write head.
  • a servo write head normally has a pair of gaps corresponding to the pair of magnetic stripes as many as the number of servo bands.
  • a core and a coil are connected to each pair of gaps, and by supplying current pulses to the coils, a magnetic field generated in the core can generate a leakage magnetic field in the pair of gaps.
  • the magnetic pattern corresponding to the pair of gaps is transferred onto the magnetic tape by inputting a current pulse while the magnetic tape is running over the servo write head, thereby forming the servo pattern. can be done.
  • the width of each gap can be appropriately set according to the density of the servo pattern to be formed.
  • the width of each gap can be set to, for example, 1 ⁇ m or less, 1 to 10 ⁇ m, or 10 ⁇ m or more.
  • the magnetic tape is usually demagnetized (erase).
  • This erasing process can be performed by applying a uniform magnetic field to the magnetic tape using a DC magnet or an AC magnet.
  • the erase process includes DC (Direct Current) erase and AC (Alternating Current) erase.
  • AC erase is performed by gradually decreasing the strength of the magnetic field while reversing the direction of the magnetic field applied to the magnetic tape.
  • DC erase is performed by applying a unidirectional magnetic field to the magnetic tape.
  • the first method is a horizontal DC erase that applies a unidirectional magnetic field along the length of the magnetic tape.
  • the second method is perpendicular DC erase, in which a unidirectional magnetic field is applied along the thickness of the magnetic tape.
  • the erase process may be performed on the entire magnetic tape, or may be performed on each servo band of the magnetic tape.
  • the direction of the magnetic field of the formed servo pattern is determined according to the erase direction. For example, when horizontal DC erasing is performed on a magnetic tape, the servo pattern is formed so that the direction of the magnetic field is opposite to the direction of erasing. As a result, the output of the servo signal obtained by reading the servo pattern can be increased.
  • the formed servo pattern is read and obtained.
  • the servo signal has a unipolar pulse shape.
  • a servo signal obtained by reading the formed servo pattern has a bipolar pulse shape.
  • the vertical squareness ratio of the magnetic tape can be, for example, 0.55 or more, preferably 0.60 or more. It is preferable from the viewpoint of improving the electromagnetic conversion characteristics that the vertical squareness ratio of the magnetic tape is 0.60 or more.
  • the upper limit of the squareness ratio is, in principle, 1.00 or less.
  • the vertical squareness ratio of the magnetic tape may be 1.00 or less, 0.95 or less, 0.90 or less, 0.85 or less, or 0.80 or less.
  • a magnetic tape having a large squareness ratio in the vertical direction is preferable from the viewpoint of improving electromagnetic conversion characteristics.
  • the perpendicular squareness ratio of the magnetic tape can be controlled by a known method such as performing a perpendicular orientation treatment.
  • the vertical squareness ratio is the squareness ratio measured in the perpendicular direction of the magnetic tape.
  • the "perpendicular direction” described with respect to the squareness ratio is the direction orthogonal to the surface of the magnetic layer, and can also be called the thickness direction.
  • the vertical squareness ratio is obtained by the following method. A sample piece of a size that can be introduced into the vibrating sample magnetometer is cut out from the magnetic tape to be measured. Using a vibrating sample magnetometer, this sample piece was measured at a maximum applied magnetic field of 3979 kA/m, a measurement temperature of 296 K, and a magnetic field sweep rate of 8.3 kA/m/sec.
  • the measured value of the magnetization intensity shall be obtained as a value after demagnetization correction and as a value obtained by subtracting the magnetization of the sample probe of the vibrating sample magnetometer as background noise.
  • the measurement temperature refers to the temperature of the sample piece, and by setting the ambient temperature around the sample piece to the measurement temperature, the temperature equilibrium is established, whereby the temperature of the sample piece can be made the measurement temperature.
  • Magnetic tape container One aspect of the present invention relates to a magnetic tape container including a core around which the magnetic tape is wound.
  • Magnetic Tape Container (Magnetic Tape Cartridge)
  • One form of the magnetic tape container is a magnetic tape cartridge.
  • a magnetic tape cartridge (hereinafter simply referred to as "cartridge”) contains a magnetic tape wound around a reel (core) inside the cartridge body.
  • a core around which a magnetic tape is wound in a magnetic tape container such as a reel of a cartridge comprises at least a hub, and flanges are usually provided at both ends of the hub.
  • the core of the magnetic tape container is rotatably provided inside the magnetic tape container.
  • the magnetic tape When a single-reel type magnetic tape cartridge is mounted on a magnetic recording/reproducing apparatus for recording and/or reproducing data on the magnetic tape, the magnetic tape is pulled out from the magnetic tape cartridge and provided in the magnetic recording/reproducing apparatus. It is wound up on a reel (hereinafter also referred to as “take-up reel”).
  • a magnetic head is arranged in the magnetic tape transport path from the magnetic tape cartridge to the take-up reel. The magnetic tape is pulled out and wound between the reel (supply reel) of the magnetic tape cartridge and the reel (take-up reel) of the magnetic recording/reproducing device.
  • data is recorded and/or reproduced by, for example, contacting and sliding between the magnetic head and the magnetic layer surface of the magnetic tape.
  • a twin-reel type magnetic tape cartridge has both a supply reel and a take-up reel inside the magnetic tape cartridge.
  • the magnetic tape container may be a single reel type magnetic tape cartridge, and in another form it may be a dual reel type magnetic tape cartridge.
  • the core from which the magnetic tape is pulled out for the measurement of roundness, which will be described later in detail is one of the two reels where the magnetic tape cartridge has not yet been installed. A reel on which, in use, a larger portion of the magnetic tape is wound.
  • the roundness measurement shall be performed using an unused magnetic tape cartridge.
  • "unused" with respect to a magnetic tape container means that the magnetic tape contained in the magnetic tape container after being provided as a product is running. is not performed.
  • the magnetic tape container is preferably a single-reel magnetic tape cartridge that has been mainly used in the data storage field in recent years.
  • the hub of the winding core is a cylindrical member that constitutes the axial center around which the magnetic tape is wound.
  • the hub of the winding core can be a single-layered cylindrical member, or can be a multi-layered cylindrical member having two or more layers. From the viewpoint of manufacturing cost and ease of manufacturing, the hub of the winding core is preferably a single-layered cylindrical member.
  • the flexural modulus of the material forming at least the outer peripheral side surface layer of the hub can be, for example, 3 GPa (gigapascal) or more.
  • the high rigidity of the core hub around which the magnetic tape is wound contributes to suppressing the above-described positional deviation in the width direction at short intervals when pulling out the wound magnetic tape. The inventor believes that it is possible. The inventor presumes that this is preferable from the viewpoint of further improving the transfer rate. From this point of view, in one embodiment, the flexural modulus of the material constituting at least the outer peripheral side surface layer of the hub is preferably 5 GPa (gigapascal) or more, more preferably 6 GPa or more, and 7 GPa or more.
  • the flexural modulus can be, for example, 20 GPa or less, 15 GPa or less, or 10 GPa or less.
  • the high flexural modulus is considered preferable for suppressing the positional deviation in the width direction in the short cycle. Therefore, the flexural modulus may exceed the values exemplified here.
  • the bending elastic modulus is the bending elastic modulus of the material that constitutes the cylindrical member.
  • the bending elastic modulus is the bending elastic modulus of the material forming at least the outer peripheral side surface layer of the hub.
  • "flexural modulus” is a value determined according to JIS (Japanese Industrial Standards) K 7171:2016.
  • JIS K 7171:2016 is a Japanese Industrial Standard created based on ISO (International Organization for Standardization) 178 and Amendment 1:2013 published as the 5th edition in 2010 without changing the technical content.
  • a test piece used for measuring the flexural modulus is prepared according to JIS K 7171:2016 Item 6 "Test piece".
  • Resin, metal, etc. can be mentioned as the material that constitutes the core hub of the reel of the magnetic tape cartridge.
  • metals include aluminum.
  • Resin is preferable from the viewpoint of cost, productivity, and the like.
  • resins include fiber-reinforced resins.
  • fiber reinforced resins include glass fiber reinforced resins and carbon fiber reinforced resins. Fiber-reinforced polycarbonate is preferable as such a fiber-reinforced resin. This is because polycarbonate is easily procured and can be molded with high precision and at low cost using a general-purpose molding machine such as an injection molding machine.
  • the glass fiber content can be, for example, 10% by mass or more, preferably 15% by mass or more.
  • the glass fiber content of the glass fiber reinforced resin may be 50% by mass or less or 40% by mass or less.
  • the resin constituting the hub is preferably glass fiber reinforced polycarbonate.
  • a high-strength resin generally called super engineering plastic can be used.
  • super engineering plastics is polyphenylene sulfide (PPS).
  • the thickness of the hub is preferably in the range of 2.0 to 3.0 mm from the viewpoint of achieving both hub strength and dimensional accuracy during molding.
  • the thickness of the hub refers to the total thickness of the multiple layers in the case of a hub having a multi-layer structure of two or more layers.
  • the outer diameter of the hub is usually determined by the standards of magnetic recording/reproducing devices, and can range, for example, from 20 to 60 mm.
  • FIG. 1 is a perspective view of an example of a magnetic tape cartridge.
  • FIG. 1 shows a single reel type magnetic tape cartridge.
  • the magnetic tape cartridge 10 shown in FIG. 1 has a case 12 .
  • the case 12 is formed in a rectangular box shape.
  • the case 12 is usually made of resin such as polycarbonate. Only one reel 20 is rotatably accommodated inside the case 12 .
  • FIG. 2 is a perspective view when starting to wind the magnetic tape around the reel.
  • FIG. 3 is a perspective view when the magnetic tape has been completely wound around the reel.
  • the reel 20 has a cylindrical reel hub 22 forming an axial center.
  • the reel hub is as described in detail above.
  • Both ends of the reel hub 22 are provided with flanges (lower flange 24 and upper flange 26) projecting radially outward from the lower end and upper end of the reel hub 22, respectively.
  • flanges lower flange 24 and upper flange 26
  • the upper side is referred to as “upper”
  • the lower side is referred to as “lower”.
  • One or both of the lower flange 24 and the upper flange 26 are preferably configured integrally with the reel hub 22 from the viewpoint of reinforcing the upper end side and/or the lower end side of the reel hub 22 .
  • Integrally configured means configured as one member instead of separate members.
  • the reel hub 22 and upper flange 26 are constructed as one piece which is joined to the separately constructed lower flange 24 in a known manner.
  • the reel hub 22 and lower flange 24 are constructed as one piece which is joined in a known manner to an upper flange 26 constructed as a separate piece.
  • the reel of the magnetic tape cartridge may be of any form.
  • Each member can be produced by a known molding method such as injection molding.
  • the magnetic tape T is wound around the outer periphery of the reel hub 22, starting from the tape inner end Tf (see FIG. 2).
  • the tension applied in the longitudinal direction of the magnetic tape when winding the magnetic tape around the reel hub is preferably 1.5 N (Newton) or less, more preferably 1.0 N or less, and is also preferably tension-free. .
  • the side wall of the case 12 has an opening 14 for pulling out the magnetic tape T wound around the reel 20.
  • the tape outer end Te of the magnetic tape T pulled out from the opening 14 is equipped with a magnetic recording/reproducing device (not shown).
  • a leader pin 16 that is pulled out while being locked by a pull-out member (not shown) is fixed.
  • the opening 14 is opened and closed by a door 18.
  • the door 18 is formed in a rectangular plate shape large enough to close the opening 14 and is biased by a biasing member (not shown) in a direction to close the opening 14 .
  • the door 18 is opened against the biasing force of the biasing member.
  • the magnetic tape is treated as a removable medium (so-called replaceable medium), and a magnetic tape cartridge (magnetic tape container) containing the magnetic tape can be inserted into the magnetic recording/reproducing device.
  • a magnetic tape cartridge containing a tape can also be removed from the magnetic recording/reproducing device.
  • FIG. 4 shows a schematic diagram of an example of a magnetic recording/reproducing apparatus in which a magnetic tape cartridge is inserted.
  • the magnetic tape cartridge 10 is inserted into the housing H of the magnetic recording/reproducing device 60 , the magnetic tape T is pulled out within the housing H, and wound onto the take-up reel 606 .
  • the housing H can be made of metal, resin, or the like, for example.
  • Data is recorded on and reproduced from the magnetic tape T by controlling the recording/reproducing head unit 602 according to commands from the control device 601 .
  • the magnetic recording/reproducing device 60 has a structure capable of detecting and adjusting the tension applied in the longitudinal direction of the magnetic tape from the spindle motors 607A and 607B that control the rotation of the cartridge reel 20 and the take-up reel 606 and their driving devices 608A and 608B. have.
  • the magnetic recording/reproducing device 60 has a configuration in which the magnetic tape cartridge 10 can be loaded.
  • the magnetic recording/reproducing device 60 has a cartridge memory read/write device 604 capable of reading from and writing to the cartridge memory 27 in the magnetic tape cartridge 10 .
  • the cartridge memory can be, for example, a non-volatile memory, and in one form, information on tension adjustment, which will be described later, is already recorded, or information on tension adjustment is recorded.
  • Information on tension adjustment is information for adjusting the tension applied to the magnetic tape in the longitudinal direction.
  • one end of the magnetic tape T or the leader pin is pulled out by an automatic loading mechanism or manually, and the magnetic layer surface of the magnetic tape T is pulled out.
  • the magnetic tape T is passed over the recording/reproducing head through guide rollers 605A and 605B in a direction in contact with the surface of the recording/reproducing head of the recording/reproducing head unit 602, and the magnetic tape T is taken up on the take-up reel 606.
  • the magnetic head contacts and slides on the surface of the magnetic layer of the magnetic tape when recording data on the magnetic tape and/or when reproducing data recorded on the magnetic tape in the magnetic recording/reproducing apparatus.
  • a magnetic recording/reproducing device is generally called a sliding drive or contact sliding drive.
  • the magnetic head records data on the magnetic tape and/or records data on the magnetic tape without contacting the surface of the magnetic layer, except when the magnetic head contacts the surface of the magnetic layer inadvertently. Play back the data that has been recorded.
  • Such a magnetic recording/reproducing device is generally called a floating drive.
  • a signal from the control device 601 controls the rotation and torque of the spindle motors 607A and 607B, and the magnetic tape T is run at an arbitrary speed and tension.
  • a servo pattern preformed on the magnetic tape can be used to control the tape speed.
  • a tension detection mechanism may be provided between the magnetic tape cartridge 10 and the take-up reel 606 to detect tension.
  • Tension adjustments may be made using guide rollers 605A and 605B in addition to the control provided by spindle motors 607A and 607B.
  • the cartridge memory read/write device 604 is configured to be able to read and write information from the cartridge memory 27 according to commands from the control device 601 .
  • the ISO International Organization for Standardization
  • the control device 601 includes, for example, a control unit, a storage unit, a communication unit, and the like.
  • the recording/reproducing head unit 602 is composed of, for example, a recording/reproducing head, a servo tracking actuator for adjusting the position of the recording/reproducing head in the track width direction, a recording/reproducing amplifier 609, a connector cable for connecting to the control device 601, and the like.
  • a recording/reproducing head is composed of, for example, a recording element for recording data on a magnetic tape, a reproducing element for reproducing data from the magnetic tape, and a servo signal reading element for reading a servo signal recorded on the magnetic tape.
  • one or more recording elements, one or more reproducing elements, and one or more servo signal reading elements are mounted in one magnetic head.
  • each element may be separately provided in a plurality of magnetic heads corresponding to the traveling direction of the magnetic tape.
  • the recording/reproducing head unit 602 is configured to be able to record data on the magnetic tape T according to commands from the control device 601 . Further, it is configured to be able to reproduce data recorded on the magnetic tape T according to a command from the control device 601 .
  • the controller 601 obtains the running position of the magnetic tape from the servo signal read from the servo band while the magnetic tape T is running, and controls the servo so that the recording element and/or the reproducing element are positioned at the target running position (track position). It has a mechanism for controlling the tracking actuator. This track position control is performed, for example, by feedback control.
  • the control device 601 has a mechanism for obtaining a servo band interval from servo signals read from two adjacent servo bands while the magnetic tape T is running. A mechanism that controls the torque of the spindle motors 607A and 607B and/or the guide rollers 605A and 605B to adjust and change the tension applied in the longitudinal direction of the magnetic tape so that the servo band interval becomes the target value.
  • control device 601 stores the obtained servo band interval information in the storage unit inside the control device 601 arranged in the housing H of the magnetic recording/reproducing device 60, and in the housing as a device separate from the control device. It can be stored in a storage device (not shown) arranged inside H, the cartridge memory 27, an external storage device (not shown) arranged outside the housing H, or the like.
  • tension can be applied in the longitudinal direction of the magnetic tape during recording and/or reproduction.
  • the tension applied in the longitudinal direction of the magnetic tape is constant in one form and varies in another form.
  • the tension can be detected by providing a tension detection mechanism between the magnetic tape cartridge 10 and the take-up reel 606 in FIG.
  • the minimum tension does not fall below the value specified or recommended by the standard, etc., and / or the maximum tension does not exceed the value specified or recommended by the standard, etc. It can also be controlled by a control device of a magnetic recording/reproducing device or the like.
  • the tension in the longitudinal direction of the magnetic tape can be variably controlled by a tension adjusting mechanism capable of adjusting the tension in the longitudinal direction of the magnetic tape running in the magnetic recording/reproducing apparatus.
  • the dimension in the width direction of the magnetic tape can be controlled by adjusting the tension applied in the longitudinal direction of the magnetic tape. In the tension adjustment described above, the tension applied to the magnetic tape in the longitudinal direction can be changed.
  • Data is recorded on the magnetic tape while the magnetic tape T is running between the take-up reel 606 and the cartridge reel 20 . Data recorded on the magnetic tape is also reproduced while the magnetic tape T is running between the take-up reel 606 and the cartridge reel 20 .
  • the magnetic tape T is normally wound around the cartridge reel 20 of the magnetic tape cartridge 10 , and the entire length of the magnetic tape T is contained within the magnetic tape cartridge 10 .
  • the magnetic tape cartridge 10 containing the magnetic tape T is held in the housing H of the magnetic recording/reproducing device 60 in one form, and is removed from the housing H in another form.
  • a thermo-hygrometer 610 can be arbitrarily arranged in the housing H of the magnetic recording/reproducing device 60 . The temperature and humidity inside the housing H of the magnetic recording/reproducing device 60 can be measured and monitored by the thermohygrometer 610 .
  • Magnetic Tape Container (Magnetic Recording/Reproducing Device)
  • Another form of the magnetic tape container is a magnetic recording/reproducing apparatus.
  • the magnetic tape is not treated as a removable medium, and the magnetic tape and the magnetic head are housed in a magnetic tape container (magnetic recording/reproducing apparatus).
  • the winding core from which the magnetic tape is pulled out for measuring the roundness which will be described in detail later, is the two reels in the unused magnetic recording/reproducing device, on which the larger part of the magnetic tape is wound. shall refer to the reel being spun.
  • the measurement of roundness which will be described in detail later, shall be performed using a magnetic recording/reproducing apparatus in an unused state.
  • FIG. 5 shows a schematic diagram of an example in which a reel on which a magnetic tape is wound and a magnetic recording/reproducing device are integrated as an example of the above embodiment.
  • the tape reel 911A and the tape reel 911B are fixed inside the housing H of the magnetic recording/reproducing device 90, and the magnetic tape T is not treated as a replaceable medium. Data is recorded on the magnetic tape while the magnetic tape T is running between the tape reels 911A and 911B. Data recorded on the magnetic tape is also reproduced while the magnetic tape T is running between the tape reels 911A and 911B. After completion of recording and/or reproduction, the magnetic tape T is usually stored in the magnetic recording/reproducing apparatus 90 with most of it wound on the tape reel 911A or the tape reel 911B.
  • control device 901 recording/reproducing head unit 902, guide rollers 905A and 905B, spindle motors 907A and 907B, driving devices 908A and 908B, recording/reproducing amplifier 909, and thermo-hygrometer 910 in FIG. 4 can be referred to above.
  • tape reels 911A and 911B reference can be made to the previous description of the parts of FIGS. 2, 3 and 4, respectively.
  • the magnetic recording/reproducing device 90 has a storage device 912 housed inside the housing H and an external storage device 913 arranged outside the housing H.
  • Controller 901 may store servo band spacing information determined, for example, as described above with respect to FIG.
  • the total length of the magnetic tape accommodated in the magnetic tape container is not particularly limited, and can be, for example, 200 m or more, or 800 m or more (for example, the range of about 800 m to 2500 m). can. From the viewpoint of increasing the capacity of the magnetic tape container, the longer the total length of the tape contained in one magnetic tape container, the better.
  • the circularity of the trajectory for one rotation drawn by the magnetic tape when the magnetic tape wound around the core is pulled out from the core is the width direction of the magnetic tape.
  • the arithmetic mean of the measured values at the three points may be, for example, 120 ⁇ m or less, preferably 100 ⁇ m or less.
  • the inventor believes that the circularity of 100 ⁇ m or less is preferable from the viewpoint of further improving the transfer rate.
  • the roundness is more preferably 95 ⁇ m or less, still more preferably 90 ⁇ m or less, even more preferably 85 ⁇ m or less, and more preferably 80 ⁇ m or less.
  • the roundness can be, for example, 30 ⁇ m or more, 35 ⁇ m or more, 40 ⁇ m or more, or 45 ⁇ m or more, or can be less than the values exemplified here.
  • a smaller circularity value is preferable from the viewpoint of further improving the transfer rate. The circularity tends to be smaller as the flexural modulus of the hub of the winding core increases.
  • the above-mentioned "roundness" in the present invention and this specification is a value obtained by the following method.
  • the following measurements are performed in a measurement environment in which the ambient temperature is in the range of 20-25° C. and the relative humidity is in the range of 40-60%.
  • the measurement is carried out after placing them in the measurement environment for one day or more.
  • the measurement method will be described below, taking as an example the case where the magnetic tape container to be measured is a single reel type magnetic tape cartridge.
  • a magnetic recording/reproducing device (drive) with a detachable magnetic tape cartridge is used to pull out the magnetic tape from the reel (core) of the magnetic tape cartridge.
  • the magnetic tape cartridge is processed as follows. After the magnetic tape cartridge to be measured is placed in the above measurement environment for one day or longer, the reel with the magnetic tape wound thereon is taken out from the case of the magnetic tape cartridge. Removal of the reel is performed in the above measurement environment. If the magnetic tape wound around the reel has a leader tape and/or a leader pin, the magnetic tape is taken out with the leader tape and/or leader pin attached. The reel (on which the magnetic tape is wound) thus taken out is placed in the above-described measurement environment until it is transferred to a case having an opening.
  • the cartridge memory is also removed.
  • the removed reel and cartridge memory are transferred from the outside of the case to a cartridge case provided with an opening so that the top surface of the upper flange of the reel and the surface of the magnetic tape can be observed with an optical discrimination sensor and a laser displacement meter, respectively.
  • the transfer to the case provided with the opening is performed in the above measurement environment.
  • the case of the magnetic tape cartridge to be measured may be processed to form the opening. The processing for forming the opening is performed while the reel with the magnetic tape wound thereon is housed in the case, or after the reel with the magnetic tape wound thereon is taken out of the case. can do.
  • the reel After placing the magnetic tape cartridge to be measured in the above-described measurement environment for one day or longer, the reel is taken out in the above-described measurement environment. If the magnetic tape wound around the reel has a leader tape and/or a leader pin, the magnetic tape is taken out with the leader tape and/or leader pin attached. The reel (on which the magnetic tape is wound) thus taken out is placed in the above measurement environment until it is housed in the case again after the opening is formed.
  • the processing for forming the opening is carried out while the reel with the magnetic tape wound is housed in the case, the magnetic tape cartridge to be measured is placed in the above measurement environment for one day or more, and then the above measurement is continued. Forming the opening is performed in the environment. Formation of the opening can be performed by a known method.
  • a light-reflecting seal or the like is affixed to the top surface of the upper flange of the reel, and the rotation cycle of the reel (winding core) of the magnetic tape cartridge is detected by detecting this with an optical discrimination sensor or the like during measurement.
  • an optical discrimination sensor for example, a light discrimination sensor capable of emitting light with a spot diameter of about 5 mm and capable of externally outputting an electric signal synchronized with the index can be used.
  • Specific examples include CZ-H35S and CZ-C21A manufactured by KEYENCE.
  • the laser spot diameter is 1.5 mm or less
  • the displacement resolution is 0.5 ⁇ m or less
  • the time resolution is 50 ⁇ m. Seconds or less, and capable of outputting an electric signal corresponding to the amount of displacement to the outside are used.
  • Specific examples of usable laser displacement meters include LK-G85 and LK-GD500 manufactured by KEYENCE.
  • the magnetic tape cartridge is inserted into the magnetic recording/reproducing apparatus, and the magnetic tape is loaded.
  • the magnetic recording/reproducing apparatus used for the measurement can be of any standard and generation as long as the magnetic tape cartridge can be mounted and the magnetic tape housed in the magnetic tape cartridge can run.
  • FIG. 6 shows a schematic diagram of the state in which the magnetic tape cartridge having the opening formed in the case is mounted in the magnetic recording/reproducing apparatus shown in FIG.
  • the upper part of the magnetic recording/reproducing apparatus may be opened, or an opening may be provided in the housing H of the magnetic recording/reproducing apparatus so that the displacement of the surface of the magnetic tape can be measured by the laser displacement meter.
  • FIG. 6 shows a schematic diagram of the state in which the magnetic tape cartridge having the opening formed in the case is mounted in the magnetic recording/reproducing apparatus shown in FIG.
  • the upper part of the magnetic recording/reproducing apparatus may be opened, or an opening may be provided in the housing H of the magnetic recording/reproducing apparatus so that the displacement of the surface of the magnetic tape can be measured by the laser displacement meter.
  • the position where the displacement of the surface of the magnetic tape is measured by the laser displacement meter is the rotational angle position where the magnetic tape is not completely unwound from the reel (core) of the magnetic tape cartridge.
  • the dotted line extending from the laser displacement gauge schematically indicates the laser beam.
  • the measurement points in the width direction of the surface of the magnetic tape are three points: the central portion in the width direction of the tape, 1 mm below the top edge, and 1 mm above the bottom edge.
  • a digital oscilloscope, a data logger, etc. are used to continuously measure the electrical signal of the displacement of the magnetic tape surface obtained by the laser displacement meter and the electrical signal of the reel rotation index obtained by the optical discrimination sensor.
  • the measurement pitch is set to a measurement pitch finer than 1 degree of reel rotation angle.
  • the electrical signal representing the displacement of the surface of the magnetic tape and the electrical signal representing the rotational index of the reel are detected by a digital oscilloscope and a data logger as described above. , etc., to measure and save.
  • the above tension value and speed value are set values in the magnetic recording/reproducing apparatus.
  • the electrical signal of displacement is converted into a displacement amount (unit: ⁇ m) using a coefficient for converting the electrical signal of displacement (voltage value) into a displacement amount, which is determined for the laser displacement meter used. Such coefficients are described, for example, in the specification sheet of the laser displacement meter.
  • the measurement result used for calculating the roundness is extracted from the measurement results of the displacement amount.
  • the end on the reel side of the magnetic tape is called the inner end, and the other end is called the outer end.
  • a length of about 50 m from the outer end of the magnetic tape is wound on the reel of the magnetic recording/reproducing device, and then the measurement results for three continuous rotations (three cycles) are extracted.
  • the roundness of the trajectory of the magnetic tape pulled out from the core is calculated for each rotation (one cycle), and three rotations are performed at three measurement points in the width direction.
  • the roundness of the trajectory for one rotation is obtained as the arithmetic mean of the minutes (three cycles).
  • the arithmetic mean of the values obtained for each of the three points is taken as the roundness value of the trajectory for one rotation of the magnetic tape in the magnetic tape cartridge (magnetic tape container) to be measured.
  • the roundness is calculated by the method (minimum area center method) specified in JISB0621:1984.
  • Circularity as defined in item 4.3 of JISB0621:1984, refers to the degree of deviation of a circular body from a geometrically correct circle (referred to as a geometric circle).
  • the circularity is two concentric circles when the distance between two concentric geometric circles is the minimum when a circular body is sandwiched between two concentric geometric circles. It is expressed by the difference in the radius of If the trajectory of the magnetic tape pulled out from the core for one rotation is a geometric circle, the distance between the laser displacement meter and the measurement position on the surface of the magnetic tape is always the same during one rotation. value (hereinafter referred to as X). However, if the trajectory deviates from the geometric circle, the distance between the laser displacement gauge and the measurement position on the surface of the magnetic tape becomes shorter or longer than X. The difference between this distance and X is the amount of displacement measured by the laser displacement meter, and from this amount of displacement, the trajectory for one rotation of the magnetic tape pulled out from the core can be drawn. The circularity of the trajectory drawn in this manner is obtained as described above.
  • the top surface of the magnetic recording/reproducing device is positioned so that the upper surface of the flange of the reel and the surface of the magnetic tape can be observed from the outside of the device with an optical discrimination sensor and a laser displacement meter, respectively. or provide an opening in the housing of the magnetic recording/reproducing device.
  • the magnetic tape container is a single unit except that the magnetic tape is wound from one reel (winding core) to the other reel by running the magnetic tape in this magnetic recording/reproducing device. The roundness is determined by the method described above for the case of a reel-type magnetic tape cartridge.
  • the magnetic tape cartridge When the magnetic tape container is a twin reel type magnetic tape cartridge, the magnetic tape cartridge is arranged so that the upper surface of the flange of the reel and the surface of the magnetic tape can be observed from the outside of the case with an optical discrimination sensor and a laser displacement meter, respectively. provide an opening in the A magnetic tape container is a single reel, except that an unused twin-reel type magnetic tape cartridge is loaded into a magnetic recording/reproducing device and the magnetic tape is wound from one reel (core) of the magnetic tape cartridge to the other reel.
  • the roundness is determined by the method described above for the case of a magnetic tape cartridge of the type.
  • the magnetic tape is usually wound around the core of the magnetic tape container and stored in the magnetic tape container.
  • the magnetic tape container is, in one form, a magnetic tape cartridge, and in another form, a magnetic recording/reproducing device including a magnetic head.
  • the term "magnetic recording/reproducing apparatus” means an apparatus capable of at least one of recording data on a magnetic tape and reproducing data recorded on the magnetic tape. Such devices are commonly referred to as drives and may be tape drives for digital data recording.
  • the magnetic tape container can be a magnetic tape cartridge, and in another form, it can be a magnetic recording/reproducing device including a magnetic head. The magnetic tape cartridge is inserted into the magnetic recording/reproducing device, the magnetic tape is run in the magnetic recording/reproducing device, and the magnetic head records data on the magnetic tape and/or reproduces the recorded data.
  • the magnetic head included in the magnetic recording/reproducing device can be a recording head capable of recording data on a magnetic tape, and a reproducing head capable of reproducing data recorded on the magnetic tape.
  • the magnetic recording/reproducing apparatus can include both a recording head and a reproducing head as separate magnetic heads.
  • the magnetic head included in the magnetic recording/reproducing device can have a configuration in which both the recording element and the reproducing element are provided in one magnetic head.
  • a magnetic head (MR head) including a magnetoresistive (MR) element capable of reading information recorded on a magnetic tape with high sensitivity as a reproducing element is preferable.
  • a magnetic head for recording and/or reproducing data may also include a servo pattern reading element.
  • the magnetic recording/reproducing apparatus may include a magnetic head (servo head) having a servo pattern reading element as a separate head from the magnetic head that records and/or reproduces data.
  • a magnetic head for recording data and/or reproducing recorded data (hereinafter also referred to as a "recording/reproducing head") can include two servo signal reading elements. Each can simultaneously read two adjacent servo bands across the data band. One or more data elements can be positioned between the two servo signal read elements.
  • An element for recording data (recording element) and an element for reproducing data (reading element) are collectively referred to as a "data element”.
  • the read element width of the read element is preferably 0.8 ⁇ m or less.
  • the read element width of the read element can be, for example, 0.1 ⁇ m or more. However, falling below this value is also preferable from the above viewpoint.
  • the narrower the width of the reproducing element the more likely it is that phenomena such as poor reproduction due to off-track will occur.
  • the "reproducing element width” means the physical dimension of the reproducing element width. Such physical dimensions can be measured with an optical microscope, scanning electron microscope, or the like.
  • head tracking using a servo signal can be performed. That is, by causing the servo signal reading element to follow a predetermined servo track, the data element can be controlled to pass over the target data track. The data track is moved by changing the servo track read by the servo signal reading element in the width direction of the tape.
  • the record/playback head can also record and/or play back other data bands.
  • the above-mentioned UDIM information is used to move the servo signal reading element to a predetermined servo band, and tracking for that servo band is started.
  • Fig. 7 shows an arrangement example of data bands and servo bands.
  • a plurality of servo bands 1 are arranged sandwiched between guide bands 3 .
  • a plurality of areas 2 sandwiched between two servo bands are data bands.
  • a servo pattern is a magnetized region formed by magnetizing a specific region of a magnetic layer with a servo write head.
  • the area magnetized by the servo write head (the position where the servo pattern is formed) is defined by standards.
  • a plurality of servo patterns inclined with respect to the tape width direction as shown in FIG. 8 are formed on the servo band when the magnetic tape is manufactured. Specifically, in FIG.
  • the servo frame SF on servo band 1 is composed of servo sub-frame 1 (SSF1) and servo sub-frame 2 (SSF2).
  • a servo subframe 1 is composed of an A burst (symbol A in FIG. 8) and a B burst (symbol B in FIG. 8).
  • the A burst is composed of servo patterns A1 to A5, and the B burst is composed of servo patterns B1 to B5.
  • servo subframe 2 is composed of a C burst (symbol C in FIG. 8) and a D burst (symbol D in FIG. 8).
  • the C burst is composed of servo patterns C1 to C4, and the D burst is composed of servo patterns D1 to D4.
  • Such 18 servo patterns are arranged in sets of 5 and 4 in subframes arranged in an array of 5, 5, 4, 4, and are used to identify servo frames.
  • FIG. 8 shows one servo frame for explanation. In practice, however, a plurality of servo frames are arranged in the running direction in each servo band on the magnetic layer of the magnetic tape on which the head tracking of the timing-based servo system is performed. In FIG. 8, arrows indicate the direction of travel.
  • an LTO Ultrium format tape typically has 5000 or more servo frames per meter of tape length in each servo band of the magnetic layer.
  • Nonmagnetic support In Table 1, "PEN” indicates polyethylene naphthalate support. Young's modulus in Table 1 is a value measured by the method described above.
  • SrFe1 in the ferromagnetic powder column indicates hexagonal strontium ferrite powder produced as follows. 1707 g of SrCO3, 687 g of H3BO3 , 1120 g of Fe2O3 , 45 g of Al(OH) 3 , 24 g of BaCO3 , 13 g of CaCO3 , and 235 g of Nd2O3 were weighed and mixed in a mixer. A raw material mixture was obtained by mixing.
  • the obtained raw material mixture was melted in a platinum crucible at a melting temperature of 1390° C., and while the melt was being stirred, a tap hole provided at the bottom of the platinum crucible was heated, and the melt was tapped in a rod shape at a rate of about 6 g/sec. .
  • the tapped liquid was rolled and quenched with a water-cooled twin roller to prepare an amorphous body.
  • 280 g of the produced amorphous material was placed in an electric furnace, heated to 635° C. (crystallization temperature) at a heating rate of 3.5° C./min, and held at the same temperature for 5 hours to produce hexagonal strontium ferrite particles. Precipitated (crystallized).
  • the crystallized product obtained above containing hexagonal strontium ferrite particles was coarsely pulverized in a mortar, and 1000 g of zirconia beads having a particle size of 1 mm and 800 mL of 1% concentration of acetic acid aqueous solution were added to a glass bottle and dispersed for 3 hours using a paint shaker. did After that, the resulting dispersion was separated from the beads and placed in a stainless steel beaker. After the dispersion liquid was allowed to stand at a liquid temperature of 100°C for 3 hours to dissolve the glass component, it was precipitated in a centrifugal separator, washed by repeating decantation, and placed in a heating furnace at a temperature of 110°C for 6 hours.
  • hexagonal strontium ferrite powder was obtained.
  • the average particle size of the hexagonal strontium ferrite powder obtained above is 18 nm
  • the activation volume is 902 nm 3
  • the anisotropy constant Ku is 2.2 ⁇ 10 5 J/m 3
  • the mass magnetization ⁇ s is 49 A ⁇ m 2 /. kg.
  • 12 mg of sample powder was taken from the hexagonal strontium ferrite powder obtained above, and the sample powder was partially dissolved under the dissolution conditions exemplified above. The surface layer content was determined. Separately, 12 mg of sample powder was taken from the hexagonal strontium ferrite powder obtained above, and the sample powder was completely dissolved under the dissolution conditions exemplified above.
  • Atomic bulk content was determined.
  • the content of neodymium atoms (bulk content) with respect to 100 atomic % of iron atoms in the hexagonal strontium ferrite powder obtained above was 2.9 atomic %.
  • the content of neodymium atoms in the surface layer was 8.0 atomic %.
  • the ratio of the surface layer portion content rate to the bulk content rate, "surface layer portion content rate/bulk content rate” was 2.8, confirming that neodymium atoms were unevenly distributed in the surface layer of the particles.
  • the fact that the powder obtained above exhibits the crystal structure of hexagonal ferrite can be confirmed by scanning CuK ⁇ rays under the conditions of a voltage of 45 kV and an intensity of 40 mA and measuring the X-ray diffraction pattern under the following conditions (X-ray diffraction analysis). confirmed.
  • the powder obtained above exhibited a crystal structure of magnetoplumbite type (M type) hexagonal ferrite.
  • the crystal phase detected by X-ray diffraction analysis was a magnetoplumbite single phase.
  • SrFe2 in the ferromagnetic powder column indicates hexagonal strontium ferrite powder produced as follows. 1725 g of SrCO3, 666 g of H3BO3 , 1332 g of Fe2O3 , 52 g of Al(OH) 3 , 34 g of CaCO3 and 141 g of BaCO3 were weighed and mixed in a mixer to obtain a raw material mixture. The obtained raw material mixture was melted in a platinum crucible at a melting temperature of 1380° C., and the melt was stirred while heating the outlet provided at the bottom of the platinum crucible to dispense the melt in a rod shape at a rate of about 6 g/sec. .
  • the tapped liquid was rolled and quenched with water-cooled twin rolls to prepare an amorphous body.
  • 280 g of the obtained amorphous material was placed in an electric furnace, heated to 645° C. (crystallization temperature), and held at the same temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles.
  • the crystallized product obtained above containing hexagonal strontium ferrite particles was coarsely pulverized in a mortar, and 1000 g of zirconia beads with a particle size of 1 mm and 800 mL of 1% concentration of acetic acid aqueous solution were added to a glass bottle, followed by dispersion treatment with a paint shaker for 3 hours.
  • the resulting dispersion was separated from the beads and placed in a stainless steel beaker. After the dispersion liquid was allowed to stand at a liquid temperature of 100°C for 3 hours to dissolve the glass component, it was precipitated in a centrifuge, washed by repeating decantation, and placed in a heating furnace at a temperature of 110°C for 6 hours. After drying for a few hours, hexagonal strontium ferrite powder was obtained.
  • the obtained hexagonal strontium ferrite powder had an average particle size of 19 nm, an activated volume of 1102 nm 3 , an anisotropy constant Ku of 2.0 ⁇ 10 5 J/m 3 , and a mass magnetization ⁇ s of 50 A ⁇ m 2 /kg. there were.
  • ⁇ -iron oxide in the column of ferromagnetic powder indicates ⁇ -iron oxide powder prepared as follows. 8.3 g of iron (III) nitrate nonahydrate, 1.3 g of gallium (III) nitrate octahydrate, 190 mg of cobalt (II) nitrate hexahydrate, 150 mg of titanium (IV) sulfate, and 4.0 g of an aqueous ammonia solution having a concentration of 25% was added to a solution of 1.5 g of polyvinylpyrrolidone (PVP) in an air atmosphere at an ambient temperature of 25° C. while stirring using a magnetic stirrer. , and the mixture was stirred for 2 hours while maintaining the ambient temperature of 25°C.
  • PVP polyvinylpyrrolidone
  • aqueous citric acid solution obtained by dissolving 1 g of citric acid in 9 g of pure water was added to the obtained solution, and the mixture was stirred for 1 hour.
  • the powder precipitated after stirring was collected by centrifugation, washed with pure water, and dried in a heating furnace with an internal furnace temperature of 80°C. 800 g of pure water was added to the dried powder, and the powder was dispersed again in water to obtain a dispersion liquid.
  • the obtained dispersion was heated to a liquid temperature of 50° C., and 40 g of an ammonia aqueous solution having a concentration of 25% was added dropwise while stirring.
  • TEOS tetraethoxysilane
  • the heat-treated ferromagnetic powder precursor is put into a 4 mol/L sodium hydroxide (NaOH) aqueous solution, and the liquid temperature is maintained at 70° C. and stirred for 24 hours to obtain a heat-treated ferromagnetic powder precursor.
  • the silicic acid compound which is an impurity, was removed from the After that, the ferromagnetic powder from which the silicic acid compound was removed was collected by centrifugal separation and washed with pure water to obtain the ferromagnetic powder.
  • the composition of the obtained ferromagnetic powder was confirmed by high-frequency inductively coupled plasma-optical emission spectrometry (ICP-OES), Ga, Co and Ti-substituted ⁇ -iron oxide ( ⁇ -Ga 0 .28 Co 0.05 Ti 0.05 Fe 1.62 O 3 ).
  • ICP-OES high-frequency inductively coupled plasma-optical emission spectrometry
  • Ga Ga
  • Co Ti-substituted ⁇ -iron oxide
  • ⁇ -Ga 0 .28 Co 0.05 Ti 0.05 Fe 1.62 O 3 X-ray diffraction analysis was performed under the same conditions as those previously described for the hexagonal strontium ferrite powder SrFe1. From the peaks of the X-ray diffraction pattern, the obtained ferromagnetic powder had an ⁇ -phase and a ⁇ -phase crystal structure.
  • the resulting ⁇ -iron oxide powder had an average particle size of 12 nm, an activated volume of 746 nm 3 , an anisotropy constant Ku of 1.2 ⁇ 10 5 J/m 3 and a mass magnetization ⁇ s of 16 A ⁇ m 2 /kg. there were.
  • the activation volume and anisotropy constant Ku of the above hexagonal strontium ferrite powder and ⁇ -iron oxide powder were obtained using a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd.) for each ferromagnetic powder, as previously described. It is a value obtained by the method of The mass magnetization ⁇ s is a value measured with a magnetic field strength of 1194 kA/m (15 kOe) using a vibrating sample magnetometer (manufactured by Toei Industry Co., Ltd.).
  • Example A1 (1) Preparation of alumina dispersion To 100.0 parts of alumina powder (HIT-80 manufactured by Sumitomo Chemical Co., Ltd.) having a gelatinization rate of about 65% and a BET (Brunauer-Emmett-Teller) specific surface area of 20 m 2 /g, 3. 0 part of 2,3-dihydroxynaphthalene (manufactured by Tokyo Kasei Co., Ltd.), a 32% solution of a polyester polyurethane resin (UR-4800 manufactured by Toyobo Co., Ltd.
  • HIT-80 manufactured by Sumitomo Chemical Co., Ltd.
  • BET Brunauer-Emmett-Teller
  • Magnetic layer forming composition Ferromagnetic powder (see Table 1) 100.0 parts SO 3 Na group-containing polyurethane resin 14.0 parts Weight average molecular weight: 70,000, SO 3 Na group: 0.2 meq/g Cyclohexanone 150.0 parts Methyl ethyl ketone 150.0 parts (abrasive liquid) 6.0 parts of the alumina dispersion prepared in (1) above (silica sol (projection forming agent liquid)) Colloidal silica (average particle size 120 nm) 2.0 parts Methyl ethyl ketone 1.4 parts (other ingredients) Stearic acid 2.0 parts Stearic acid amide 0.2 parts Butyl stearate 2.0 parts Polyisocyanate (Coronate (registered trademark) L manufactured by Tosoh Corporation) 2.5 parts (finishing additive solvent) Cyclohexanone 200.0 parts Methyl ethyl ketone 200.0 parts
  • Non-magnetic inorganic powder ⁇ -iron oxide 100.0 parts Average particle size (average major axis length): 0.15 ⁇ m Average acicular ratio: 7 BET specific surface area: 52 m 2 /g Carbon black 20.0 parts Average particle size: 20 nm SO 3 Na group-containing polyurethane resin 18.0 parts Weight average molecular weight: 70,000, SO 3 Na group: 0.2 meq/g Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., number average molecular weight 600) See Table 1 Stearic acid See Table 1 Stearamide 0.2 parts Butyl stearate 2.0 parts Cyclohexanone 300.0 parts Methyl ethyl ketone 300.0 parts
  • composition for forming backcoat layer Carbon black 100.0 parts DBP (Dibutyl phthalate) oil absorption 74 cm 3 /100 g Nitrocellulose 27.0 parts
  • Polyester polyurethane resin containing sulfonic acid groups and/or salts thereof 62.0 parts
  • Polyester resin 4.0 parts Alumina powder (BET specific surface area: 17 m 2 /g) 0.6 parts
  • Polyethyleneimine Japan Catalyst Co., Ltd., number average molecular weight 600
  • Stearic acid See Table 1 Methyl ethyl ketone 600.0 parts Toluene 600.0 parts Polyisocyanate (Coronate (registered trademark) L manufactured by Tosoh Corporation) 15.0 parts
  • a magnetic layer-forming composition was prepared by the following method.
  • the above magnetic liquid was prepared by dispersing (bead dispersion) each component for 24 hours using a batch-type vertical sand mill.
  • As dispersion beads zirconia beads with a bead diameter of 0.5 mm were used.
  • the prepared magnetic liquid, the abrasive liquid, the silica sol, other components, and the finishing additive solvent were mixed and dispersed in beads for 5 minutes, followed by 0.5 minutes with a batch-type ultrasonic device (20 kHz, 300 W). Treatment (ultrasonic dispersion) was performed.
  • a composition for forming a non-magnetic layer was prepared by the following method.
  • the above ingredients except for stearic acid, stearic acid amide and butyl stearate were kneaded and diluted by an open kneader, and then dispersed by a horizontal bead mill disperser. After that, stearic acid, stearic acid amide and butyl stearate were added and stirred and mixed with a dissolver stirrer to prepare a composition for forming a non-magnetic layer.
  • a composition for forming a backcoat layer was prepared by the following method.
  • the components except for the polyisocyanate were introduced into a dissolver stirrer, stirred at a peripheral speed of 10 m/sec for 30 minutes, and then dispersed using a horizontal bead mill disperser. After that, polyisocyanate was added, and the mixture was stirred and mixed with a dissolver stirrer to prepare a composition for forming a backcoat layer.
  • the backcoat layer-forming film prepared in (5) above was applied so that the thickness after drying was as shown in Table 1.
  • the composition was applied and dried to form a backcoat layer.
  • the surface is smoothed (calendered) at the calender speed, calender pressure (linear pressure), and calender temperature (surface temperature of the calender roll) shown in Table 1.
  • heat treatment was performed by storing the long magnetic tape raw material in a heat treatment furnace with an atmospheric temperature of 70° C. (heat treatment time: 36 hours).
  • the film was slit to a width of 1/2 inch to obtain a magnetic tape.
  • a servo signal on the magnetic layer of the obtained magnetic tape with a commercially available servo writer
  • a data band, a servo band, and a guide band are arranged in accordance with the LTO (Linear Tape-Open) Ultrium format, and the servo
  • a magnetic tape having a servo pattern (timing-based servo pattern) arranged and shaped according to the LTO Ultrium format on the band was obtained.
  • the servo pattern thus formed is a servo pattern according to the descriptions of JIS (Japanese Industrial Standards) X6175:2006 and Standard ECMA-319 (June 2001).
  • the total number of servo bands is five, and the total number of data bands is four.
  • the magnetic tape (length 970 m) after forming the servo pattern was wound around a core for heat treatment, and heat-treated while being wound around the core.
  • a core for heat treatment a resin-made solid core member (outer diameter: 50 mm) having a bending elastic modulus of 0.8 GPa was used, and the tension during winding was set to 0.6 N.
  • the heat treatment was performed at the heat treatment temperature shown in Table 1 for 5 hours.
  • the weight absolute humidity of the heat-treated atmosphere was 10 g/kg Dry air.
  • the magnetic tape is removed from the heat treatment core, wound on the temporary take-up core, and then removed from the temporary take-up core to the magnetic tape cartridge ( Wind the magnetic tape for the final product length (960 m) onto a reel (reel outer diameter: 44 mm) of LTO Ultrium 7 data cartridge), cut off the remaining 10 m, and attach Standard ECMA ( A leader tape was spliced according to European Computer Manufacturers Association)-319 (June 2001) Section 3, Item 9.
  • the winding core for temporary winding a solid core member made of the same material as the winding core for heat treatment and having the same outer diameter was used, and the tension during winding was set to 0.6N.
  • the reel hub of this magnetic tape cartridge is a single-layer reel hub (thickness: 2.5 mm, outer diameter: 44 mm) injection-molded from glass fiber reinforced polycarbonate.
  • the glass fiber content of this glass fiber reinforced polycarbonate is the value shown in Table 1.
  • a part of the glass fiber reinforced polycarbonate for injection molding was collected, and according to JIS K 7171: 2016, item 6.3.1 (manufacture from molding material), described in item 6.1.2 of the same JIS.
  • a recommended test piece was prepared, and the flexural modulus (arithmetic average of five test pieces) was determined according to the same JIS.
  • the flexural modulus of the reel hub material was determined by the above method.
  • the flexural modulus of the core for heat treatment is also determined in the same manner.
  • the magnetic tape was wound around the reel hub of the magnetic tape cartridge while applying a tension of 1.0 N or less in the longitudinal direction of the tape, and the magnetic tape was housed in the magnetic tape cartridge.
  • a single-reel type magnetic tape cartridge of Example A1 in which a magnetic tape having a length of 960 m was wound around a reel was produced.
  • the presence of the compound containing the ammonium salt structure of the alkyl ester anion represented by Formula 1 formed by polyethyleneimine and stearic acid in the magnetic tape can be confirmed by the method described above.
  • the backcoat layer contains a compound containing an ammonium salt structure of an alkyl ester anion represented by formula 1 formed by polyethyleneimine and stearic acid.
  • a sample is cut out from the magnetic tape, and X-ray photoelectron spectroscopic analysis is performed on the surface of the backcoat layer (measurement area: 300 ⁇ m ⁇ 700 ⁇ m) using an ESCA device. Specifically, wide scan measurement is performed with an ESCA device under the following measurement conditions.
  • tape thickness Ten tape samples (5 cm in length) were cut out from an arbitrary portion of the magnetic tape, and these tape samples were stacked to measure the thickness. Thickness measurements were made using a MARH Millimar 1240 compact amplifier and a Millimar 1301 inductive probe digital thickness gauge. The value (thickness per tape sample) obtained by dividing the measured thickness by 1/10 was taken as the tape thickness. The tape thickness was the value shown in Table 1.
  • the average distance AC between the corresponding four stripes of the A burst and the C burst and the azimuth angle ⁇ of the servo pattern are measured.
  • a reel tester and a servo head equipped with two servo signal reading elements (hereinafter referred to as the upper side and the other as the lower side) spaced apart in a direction perpendicular to the longitudinal direction of the magnetic tape. are used to sequentially read the servo patterns formed on the magnetic tape along the longitudinal direction of the tape.
  • a as the average time between 5 stripes corresponding to A and B bursts over the length of 1 LPOS word.
  • b Define b as the average time of the corresponding 4 stripes of the A and C bursts over the length of 1 LPOS word.
  • the value defined by AC ⁇ (1/2 ⁇ a/b)/(2 ⁇ tan( ⁇ )) is the width direction based on the servo signal obtained by the servo signal reading element over the length of 1 LPOS word. represents the reading position PES of .
  • the reading of the servo pattern for one LPOS word is done simultaneously by the two upper and lower servo signal reading elements.
  • PES1 be the PES value obtained by the upper servo signal reading element
  • PES2 be the PES value obtained by the lower servo signal reading element.
  • the magnetic tape cartridge was inserted into a magnetic recording/reproducing apparatus, and data was recorded on the magnetic tape and the recorded data was reproduced.
  • a magnetic recording/reproducing apparatus a recording/reproducing unit having 32 or more channels of a reproducing element and a recording element with a reproducing element width of 0.8 ⁇ m, and having servo signal reading elements on both sides thereof, has the configuration shown in FIG. A recording and playback device was used. After acclimatizing the magnetic tape cartridge and the magnetic recording/reproducing apparatus to the measurement environment (atmospheric temperature 20-25° C., relative humidity 40-60%) for at least one day, recording and reproduction were performed over the full length of the tape.
  • the maximum capacity of the magnetic tape was recorded and reproduced using drive control software. Further, during recording and reproduction, the tension applied to the magnetic tape in the longitudinal direction changed due to the tension adjustment performed by the controller of the magnetic recording and reproducing apparatus.
  • the transfer rate is calculated as the recorded or played back capacity per unit time (MB (megabytes)/second) by dividing the "recorded or played back capacity" by the "time required for recording or playback.” bottom.
  • MB microbytes
  • Table 1 shows the transfer rate as a relative value assuming that the maximum transfer rate in the combination of the magnetic recording/reproducing device and the magnetic tape is 100.0%.
  • the recording/reproducing head mounted on the recording/reproducing head unit 602 has 32 or more channels of reproducing elements (reproducing element width: 0.8 ⁇ m) and recording elements, and has servo signal reading elements on both sides thereof.
  • Each magnetic tape cartridge of Example A1 was placed in an environment with an ambient temperature of 23° C. and a relative humidity of 50% for 5 days or more. After acclimatizing to the environment in this way, data was recorded as follows in the same environment. A magnetic tape cartridge is set in the magnetic recording/reproducing device, and the magnetic tape is loaded.
  • pseudo-random data having a specific data pattern is recorded on the magnetic tape by the recording/reproducing head unit while performing servo tracking.
  • the tension applied in the longitudinal direction of the tape is 0.7N.
  • three or more reciprocations are performed so that the difference in the value of (PES1+PES2)/2 between adjacent tracks is 1.16 ⁇ m.
  • the value of the servo band interval over the entire length of the tape is measured every 1 m of the longitudinal position and recorded in the cartridge memory.
  • the magnetic tape cartridge on which data was recorded as described above was placed in a storage environment with an ambient temperature of 60° C. and a relative humidity of 20% for 72 hours.
  • the magnetic tape cartridge of Example A1 was placed in an environment with an ambient temperature of 23° C. and a relative humidity of 50% for 5 days or longer. After acclimatization to the environment, the data was reproduced in the same environment as follows. A magnetic tape cartridge is set in the magnetic recording/reproducing device, and the magnetic tape is loaded. Next, while performing servo tracking, the data recorded on the magnetic tape is reproduced by the recording/reproducing head unit. At that time, the value of the servo band interval is measured at the same time as the reproduction. Adjust the tension in the direction. During playback, measurement of the servo band interval and adjustment of tension based thereon are continuously performed in real time.
  • Example A1 the tension value used by the control device 601 for the tension adjustment was in the range of 0.2 to 1.2N.
  • the number of channels in the above playback is 32 channels, and the recording/playback performance is evaluated as "3" when the data of all 32 channels are correctly read during playback, and the recording is performed when the data of the 31st to 28th channels are correctly read.
  • the reproduction performance was evaluated as "2", and the other cases were evaluated as the recording and reproduction performance as "1".
  • Examples A2 to A23, Examples B1 to B18 A magnetic tape cartridge was fabricated and variously evaluated as described for Example A1, except that the items in Table 1 were changed as shown in Table 1.
  • Table 1 in the examples described as “none” in the “heat treatment temperature” column, the heat treatment was not performed while being wound around the core for heat treatment.
  • the following points can be confirmed. From the comparison between Examples A1 to A23 and B15 to B18 and Examples B1 to B14, it can be seen that the ⁇ w and CV of the magnetic tape are within the ranges described above, enabling recording and reproduction at a high transfer rate. can be confirmed to contribute to From the comparison between Examples A1 to A23 and Examples B1 to B18, the magnetic tape including a polyethylene naphthalate support having a Young's modulus in the width direction of 10000 MPa or more as a non-magnetic support adjusts the tension applied to the magnetic tape in the longitudinal direction. Therefore, it can be confirmed that the magnetic tape can be suitably used in a magnetic recording/reproducing apparatus for controlling the dimension in the width direction of the magnetic tape.
  • a magnetic tape cartridge was fabricated in the manner previously described for Example A1, except that no vertical orientation treatment was performed during the fabrication of the magnetic tape.
  • a sample piece was cut out from the magnetic tape taken out from the magnetic tape cartridge.
  • the squareness ratio in the vertical direction of this sample piece was found to be 0.55 by using the TM-TRVSM5050-SMSL model manufactured by Tamagawa Seisakusho as a vibrating sample magnetometer by the method described above.
  • a magnetic tape was taken out from the magnetic tape cartridge of Example A1, and the vertical squareness ratio of a sample piece cut out from this magnetic tape was similarly determined to be 0.60.
  • the magnetic tapes taken out from the above two magnetic tape cartridges were each attached to a 1/2 inch reel tester, and the electromagnetic conversion characteristics (SNR: Signal-to-Noise Ratio) were evaluated by the following method. As a result, a 2 dB higher SNR value was obtained for the magnetic tape taken out from the magnetic tape cartridge of Example A1 than for the magnetic tape produced without the perpendicular orientation treatment. In an environment of temperature 23° C. and relative humidity 50%, 10 passes of recording and reproduction were performed by applying a tension of 0.7 N in the longitudinal direction of the magnetic tape.
  • the relative speed between the magnetic tape and the magnetic head was 6 m/sec, and recording was performed using a MIG (Metal-in-gap) head (gap length 0.15 ⁇ m, track width 1.0 ⁇ m) as a recording head, and recording current.
  • the optimum recording current was set for each magnetic tape.
  • Reproduction was performed using a GMR (Giant-Magnetoresistive) head (element thickness: 15 nm, shield interval: 0.1 ⁇ m, reproduction element width: 0.8 ⁇ m).
  • a signal with a linear recording density of 300 kfci was recorded, and the reproduced signal was measured with a spectrum analyzer manufactured by Shibasoku.
  • the unit kfci is the unit of linear recording density (cannot be converted to the SI unit system). As the signal, a portion where the signal was sufficiently stabilized after the magnetic tape started running was used.
  • One aspect of the present invention is useful in the technical field of various data storage such as backup and archive.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

La présente invention concerne une bande magnétique comprenant un support non magnétique et une couche magnétique contenant de la poudre ferromagnétique. La quantité de variation dimensionnelle Δw dans le sens de la largeur par rapport à une variation de tension dans le sens longitudinal est comprise entre 400 ppm/N et 900 ppm/N (les deux inclus), le support non magnétique est un support en polyéthylène naphtalate dont le module de Young dans le sens de la largeur est de 10 000 MPa ou plus, la couche magnétique comprend une pluralité de bandes d'asservissement, et un coefficient de variation CV calculé à partir de l'équation A : CV = (σG/Δw) × 100 est 10 % ou moins, σG représentant un écart type d'intervalles de bande d'asservissement mesuré dans une zone s'étendant sur 100 mètres dans le sens longitudinal de la bande magnétique avec une tension de 0,6 N appliquée sur celle-ci dans le sens longitudinal.
PCT/JP2022/043983 2021-12-02 2022-11-29 Bande magnétique et corps d'enveloppement de bande magnétique WO2023100869A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5523584U (fr) * 1978-08-02 1980-02-15
JP2019021363A (ja) * 2017-07-19 2019-02-07 富士フイルム株式会社 磁気テープおよび磁気テープ装置
WO2019171665A1 (fr) * 2018-03-09 2019-09-12 ソニー株式会社 Bande d'enregistrement magnétique, son procédé de fabrication et cartouche de bande d'enregistrement magnétique
JP2021108236A (ja) * 2020-07-03 2021-07-29 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
JP2021125279A (ja) * 2020-02-07 2021-08-30 富士フイルム株式会社 磁気テープ装置、磁気テープおよび磁気テープカートリッジ
JP2021125273A (ja) * 2020-01-31 2021-08-30 富士フイルム株式会社 磁気テープ、磁気テープカートリッジおよび磁気テープ装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5523584U (fr) * 1978-08-02 1980-02-15
JP2019021363A (ja) * 2017-07-19 2019-02-07 富士フイルム株式会社 磁気テープおよび磁気テープ装置
WO2019171665A1 (fr) * 2018-03-09 2019-09-12 ソニー株式会社 Bande d'enregistrement magnétique, son procédé de fabrication et cartouche de bande d'enregistrement magnétique
JP2021125273A (ja) * 2020-01-31 2021-08-30 富士フイルム株式会社 磁気テープ、磁気テープカートリッジおよび磁気テープ装置
JP2021125279A (ja) * 2020-02-07 2021-08-30 富士フイルム株式会社 磁気テープ装置、磁気テープおよび磁気テープカートリッジ
JP2021108236A (ja) * 2020-07-03 2021-07-29 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

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