WO2024075416A1 - 磁気テープおよびテープカートリッジ - Google Patents

磁気テープおよびテープカートリッジ Download PDF

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Publication number
WO2024075416A1
WO2024075416A1 PCT/JP2023/030077 JP2023030077W WO2024075416A1 WO 2024075416 A1 WO2024075416 A1 WO 2024075416A1 JP 2023030077 W JP2023030077 W JP 2023030077W WO 2024075416 A1 WO2024075416 A1 WO 2024075416A1
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WO
WIPO (PCT)
Prior art keywords
tape
magnetic
magnetic tape
less
substrate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
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PCT/JP2023/030077
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English (en)
French (fr)
Japanese (ja)
Inventor
栄治 中塩
洋 熊谷
菅原　正樹
妙子 高橋
孝信 岩間
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Sony Group Corp
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Sony Group Corp
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Publication date
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Priority to JP2024555652A priority Critical patent/JPWO2024075416A1/ja
Priority to US19/112,457 priority patent/US20260105930A1/en
Publication of WO2024075416A1 publication Critical patent/WO2024075416A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/008—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires
    • G11B5/00813—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes
    • 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
    • G11B23/037—Single reels or spools
    • 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
    • G11B5/62—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
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—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
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers

Definitions

  • This technology relates to magnetic tape and the tape cartridge that houses it.
  • a tape drive device In a single-reel tape cartridge, a tape drive device is used to record information onto the magnetic tape or to play back information recorded on the magnetic tape.
  • the magnetic tape When a tape cartridge is loaded into the tape drive device, the magnetic tape is pulled out of the tape cartridge and wound onto a take-up reel on the tape drive device side.
  • a magnetic head is disposed in the tape path from the tape cartridge to the take-up reel. The magnetic tape is then moved relative to the magnetic head by the take-up reel winding and rewinding of the magnetic tape from the take-up reel, allowing the magnetic head to record or play back information.
  • full-height drive devices that are used in large-scale libraries
  • half-height drive devices that are half the height of full-height drive devices are also known (see, for example, Patent Document 2).
  • Full-height and half-height tape drive devices differ only in height, and there is no significant difference in the performance of recording and reproducing information from tape cartridges, so currently, users use them according to their operating environment.
  • the relative position of the tape to the magnetic head may fluctuate due to factors such as an unavoidable decrease in linearity during the manufacturing process of the magnetic tape and a decrease in the geometric precision of the take-up reel inside the tape drive device, which may interfere with the normal recording or reproducing operation of information by the magnetic head.
  • the objective of this technology is to provide a magnetic tape and a tape cartridge equipped with the same that can ensure stable recording and playback characteristics regardless of the type of tape drive device.
  • a magnetic tape according to one embodiment of the present technology is a magnetic tape having a substrate and a magnetic layer provided on one main surface of the substrate,
  • the substrate is made of polyethylene naphthalate (PEN)
  • the magnetic tape has a total thickness of 4.9 ⁇ m to 5.4 ⁇ m
  • the magnetic tape has a loop stiffness in the width direction of 1.1 mg/ ⁇ m to 1.4 mg/ ⁇ m.
  • the magnetic tape may further include a non-magnetic layer provided between the substrate and the magnetic layer, and a back layer provided on the other main surface of the substrate.
  • the thickness of the substrate may be 4.2 ⁇ m or less, 4.1 ⁇ m or less, or 4.0 ⁇ m or less.
  • the magnetic layer may contain magnetic powder of hexagonal ferrite, ⁇ -iron oxide, or cobalt-containing ferrite.
  • the squareness ratio of the magnetic layer in the longitudinal direction of the magnetic tape may be 35% or less.
  • the coercivity of the magnetic layer may be 2000 Oe or less.
  • the magnetic tape may have a longitudinal shrinkage rate of 0.1% or less when stored at 70°C for 48 hours.
  • a tape cartridge includes a tape reel and a magnetic tape.
  • the tape reel has a first flange, a second flange, and a cylindrical reel hub having a first end integrally formed with the first flange and a second end to which the second flange is joined.
  • the magnetic tape has a substrate and a magnetic layer provided on one main surface of the substrate, and is wound around the outer circumferential surface of the reel hub.
  • the substrate is made of polyethylene naphthalate (PEN)
  • the magnetic tape has a total thickness of 4.9 ⁇ m to 5.4 ⁇ m
  • the magnetic tape has a loop stiffness in the width direction of 1.1 mg/ ⁇ m to 1.4 mg/ ⁇ m.
  • the magnetic tape may be curved in a convex shape toward the second flange, and the deviation from a chord of 1 m of the magnetic tape may be 3.8 mm or less.
  • the inner surface of the first flange and the inner surface of the second flange may be formed with a tapered surface that opens toward the outer periphery of the tape reel.
  • the minimum distance between the first flange and the second flange along the axial direction of the hub may be 12.9 mm ⁇ 0.14 mm.
  • the maximum distance between the first flange and the second flange along the axial direction of the hub may be 13.125 mm ⁇ 0.195 mm.
  • FIG. 1 is an overall perspective view of a tape cartridge according to one embodiment of the present technology, where (A) is a perspective view seen from the top (upper shell) side, and (B) is a perspective view seen from the bottom (lower shell) side.
  • FIG. 2 is an exploded perspective view of the tape cartridge.
  • FIG. 2 is an exploded cross-sectional side view of the tape cartridge.
  • 1 is a schematic diagram showing a magnetic tape according to an embodiment of the present invention as viewed from the side;
  • FIG. 1 is a plan view showing a schematic configuration of a tape drive device.
  • FIG. 2 is a schematic diagram illustrating the curvature direction of a magnetic tape.
  • 1A and 1B are schematic diagrams illustrating the state of the magnetic tape wound around the take-up reel, where (A) shows the state when the curvature direction of the magnetic tape is negative, and (B) shows the state when the curvature direction of the magnetic tape is positive.
  • 2 is a schematic side view showing a configuration of a tape reel in the tape cartridge.
  • FIG. 1 is an overall perspective view of a tape cartridge 1 according to one embodiment of the present technology, where (A) is a perspective view seen from the top (upper shell 2) side, and (B) is a perspective view seen from the bottom (lower shell 3) side.
  • FIG. 2 is an exploded perspective view of the tape cartridge 1
  • FIG. 3 is an exploded cross-sectional side view thereof.
  • the tape cartridge 1 of this embodiment has a configuration in which a single tape reel 5 around which a magnetic tape 22 is wound is rotatably housed inside a cartridge case 4 formed by joining an upper shell 2 and a lower shell 3 with a plurality of screw members.
  • the tape cartridge 1 of this embodiment will be described below using a magnetic tape cartridge conforming to the LTO (Linear Tape Open) standard as an example.
  • the tape reel 5 has a cylindrical reel hub 6 with a bottom, a lower flange 7 integrally formed with the lower end of the reel hub 6, and an upper flange 8 joined to the upper end of the reel hub 6, each of which is made from an injection molded synthetic resin material.
  • a chucking gear 9 is formed in an annular shape in the center of the underside of the tape reel 5, which engages with the reel rotation drive shaft of the tape drive device, and is exposed to the outside through an opening 10 provided in the center of the lower shell 3, as shown in FIG. 1(B).
  • an annular metal plate 11 that is magnetically attracted to the reel rotation drive shaft is fixed to the bottom outer surface of the reel hub 6 by insert molding.
  • a reel lock mechanism is provided inside the reel hub 6 to prevent the tape reel 5 from rotating when the tape cartridge 1 is not in use.
  • the reel lock mechanism includes a plurality of gear forming walls 12 erected on the upper surface of the bottom 60 of the reel hub 6, a reel lock member 13 having engagement teeth 13a that mesh with a gear portion 12a formed on the upper surface of the gear forming walls 12, a reel lock release member 14 for releasing the engagement between the gear forming walls 12 and the reel lock member 13, and a reel spring 15 provided between the inner surface of the upper shell 2 and the upper surface of the reel lock member 13.
  • the reel spring 15 is a coil spring, and biases the tape reel 5 toward the lower shell 3 via the reel lock member 13.
  • the gear forming wall 12 has an arc shape and is formed on the upper surface of the bottom 60 of the reel hub 6 at three equally spaced locations on the same circumference around the axis of the reel hub 6.
  • the engagement teeth 13a of the reel lock member 13 that face the gear portion 12a of the gear forming wall 12 are formed in an annular shape on the lower surface of the reel lock member 13 and are constantly biased in the direction of engagement with the gear portion 12a by receiving a reel spring 15.
  • An engagement protrusion 13c is formed on the upper surface of the reel lock member 13, and an engagement recess 2a that fits into this engagement protrusion 13c is formed in the approximate center of the inner surface of the upper shell 2.
  • the reel lock release member 14 has a roughly triangular shape and is disposed between the bottom 60 of the reel hub 6 and the reel lock member 13.
  • a total of three legs 14a protrude downward from the bottom surface of the reel lock release member 14 near each apex of the roughly triangular shape, and these legs are positioned between the gears of the chucking gear 9 via insertion holes 6a formed in the bottom 60 of the reel hub 6 when the cartridge is not in use.
  • each leg 14a of the reel lock release member 14 is pressed upward by the reel rotation drive shaft of the tape drive device that engages with the chucking gear 9, thereby moving the reel lock member 13 to the unlocked position against the biasing force of the reel spring 15.
  • the reel lock release member 14 is configured to be rotatable relative to the reel lock member 13 together with the tape reel 5.
  • a support surface 14b is provided at approximately the center of the upper surface of the reel lock release member 14 to support a sliding contact portion 13b with an arc-shaped cross section that is formed and protrudes from approximately the center of the lower surface of the reel lock member 13.
  • One side wall 26 of the cartridge case 4 is provided with a pull-out opening 27 for pulling out one end of the magnetic tape 22 to the outside.
  • a sliding door 29 for opening and closing the pull-out opening 27 is disposed inside the side wall 26.
  • the sliding door 29 is configured to slide in a direction that opens the pull-out opening 27 against the biasing force of the torsion spring 57 by engaging with a tape loading mechanism (not shown) of the tape drive device.
  • a leader pin 31 is fixed to one end of the magnetic tape 22.
  • the leader pin 31 is configured to be detachable from a pin holding portion 33 provided on the inside side of the pull-out opening 27.
  • the pin holding portions 33 are attached to the inner surface of the upper shell 2 and the inner surface of the lower shell 3, respectively, and are configured to be able to elastically hold the upper end and lower end of the leader pin 31, respectively.
  • the cartridge memory 54 is made up of a contactless communication medium that has an antenna coil, IC chip, etc. mounted on a substrate.
  • FIG. 4 is a schematic diagram of the magnetic tape 22 as seen from the side.
  • the magnetic tape 22 is configured as a tape that is long in the longitudinal direction (X-axis direction), short in the width direction (Y-axis direction), and thin in the thickness direction (Z-axis direction).
  • the magnetic tape 22 includes a tape-shaped substrate 41 that is long in the longitudinal direction (X-axis direction), an underlayer (non-magnetic layer) 42 provided on one main surface of the substrate 41, a magnetic layer 43 provided on the underlayer 42, and a back layer 44 provided on the other main surface of the substrate 41. Note that the back layer 44 may be provided as necessary, and may be omitted.
  • the magnetic tape 22 may be a perpendicular recording type magnetic recording medium or a longitudinal recording type magnetic recording medium.
  • the magnetic tape 22 has a long tape shape, and runs in the longitudinal direction during recording and playback.
  • the surface of the magnetic layer 43 is the surface over which the magnetic head of the recording and playback device (tape drive device, see Figure 5) runs.
  • the magnetic tape 22 is preferably used in a recording and playback device that has a ring-type head as the recording head.
  • the magnetic tape 22 is preferably used in a recording and playback device that is configured to be able to record data with a data track width of 1500 nm or less or 1000 nm or less.
  • the substrate 41 is a non-magnetic support that supports the underlayer 42 and the magnetic layer 43.
  • the substrate 41 has a long film shape.
  • the upper limit of the average thickness of the substrate 41 is preferably 4.4 ⁇ m or less, more preferably 4.2 ⁇ m or less, and even more preferably 4.0 ⁇ m or less.
  • the lower limit of the average thickness of the substrate 41 is preferably 3 ⁇ m or more, more preferably 3.2 ⁇ m or more.
  • the lower limit of the average thickness of the substrate 41 is 3 ⁇ m or more, the strength reduction of the substrate 41 can be suppressed.
  • the average thickness of the substrate 41 is found as follows. First, a 1/2 inch wide magnetic tape 22 is prepared and cut to a length of 250 mm to prepare a sample. Next, layers other than the substrate 41 of the sample (i.e., the underlayer 42, the magnetic layer 43, and the back layer 44) are removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Next, using a Mitutoyo Laser Hologram (LGH-110C) as a measuring device, the thickness of the sample (substrate 41) is measured at five or more positions, and the measured values are simply averaged (arithmetic mean) to calculate the average thickness of the substrate 41. Note that the measurement positions are selected randomly from the sample.
  • a Mitutoyo Laser Hologram LGH-110C
  • the substrate 41 contains polyester. By including polyester in the substrate 41, the Young's modulus of the substrate 41 in the longitudinal direction can be reduced. Therefore, by adjusting the longitudinal tension of the magnetic tape 22 while it is running using the recording/playback device, the width of the magnetic tape 22 can be kept constant or nearly constant.
  • the polyester includes, for example, at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polycyclohexylene dimethylene terephthalate (PCT), polyethylene-p-oxybenzoate (PEB), and polyethylene bisphenoxycarboxylate.
  • PET polyethylene terephthalate
  • PEN polyethylene naphthalate
  • PBT polybutylene terephthalate
  • PBN polybutylene naphthalate
  • PCT polycyclohexylene dimethylene terephthalate
  • PEB polyethylene-p-oxybenzoate
  • polyethylene bisphenoxycarboxylate polyethylene bisphenoxycarboxylate.
  • the substrate 41 includes two or more types of polyester, the two or more types of polyester may be mixed, copolymerized, or laminated. At least one of the terminals and side chains of the polyester may be modified.
  • polyester in substrate 41 can be confirmed, for example, as follows. First, in the same manner as in measuring the average thickness of substrate 41, layers of the sample other than substrate 41 are removed. Next, an IR spectrum of the sample (substrate 41) is obtained by infrared absorption spectrometry (IR). Based on this IR spectrum, it can be confirmed that substrate 41 contains polyester.
  • IR infrared absorption spectrometry
  • the substrate 41 may further include at least one of polyamide, polyetheretherketone, polyimide, and polyamideimide, or may further include at least one of polyamide, polyimide, polyamideimide, polyolefins, cellulose derivatives, vinyl resins, and other polymer resins.
  • the polyamide may be an aromatic polyamide (aramid).
  • the polyimide may be an aromatic polyimide.
  • the polyamideimide may be an aromatic polyamideimide.
  • the substrate 41 contains a polymer resin other than polyester
  • the substrate 41 contains polyester as a main component.
  • the main component means the component with the largest content (mass ratio) among the polymer resins contained in the substrate 41.
  • the polyester and the polymer resin other than polyester may be mixed or copolymerized.
  • the substrate 41 may be biaxially stretched in the longitudinal and width directions.
  • the polymer resin contained in the substrate 41 is preferably oriented in a direction oblique to the width direction of the substrate 41.
  • the magnetic layer 43 is a recording layer for recording signals by magnetization patterns.
  • the magnetic layer 43 may be a perpendicular recording type recording layer or a longitudinal recording type recording layer.
  • the magnetic layer 43 includes, for example, a magnetic powder, a binder, and a lubricant.
  • the magnetic layer 43 may further include at least one additive selected from antistatic agents, abrasives, hardeners, rust inhibitors, and non-magnetic reinforcing particles, as necessary.
  • the magnetic layer 43 is not limited to being composed of a coating film of a magnetic material, and may be composed of a sputtered film or a vapor deposition film of a magnetic material.
  • the arithmetic mean roughness Ra of the surface of the magnetic layer 43 is 2.0 nm or less, preferably 1.8 nm or less, and more preferably 1.6 nm or less.
  • the lower limit of the arithmetic mean roughness Ra of the surface of the magnetic layer 43 is preferably 1.0 nm or more, and more preferably 1.2 nm or more.
  • the lower limit of the arithmetic mean roughness Ra of the surface of the magnetic layer 43 is 1.0 nm or more, deterioration of running properties due to increased friction can be suppressed.
  • the arithmetic mean roughness Ra is calculated as follows. First, the surface of the magnetic layer 43 is observed by an AFM (Atomic Force Microscope) to obtain an AFM image of 40 ⁇ m ⁇ 40 ⁇ m.
  • the AFM used is a Nano Scope IIIa D3100 manufactured by Digital Instruments, and the cantilever is made of single crystal silicon (Note 1). The measurement is performed with a tapping frequency of 200 to 400 Hz.
  • the upper limit of the average thickness tm of the magnetic layer 43 is 80 nm or less, preferably 70 nm or less, and more preferably 50 nm or less. If the upper limit of the average thickness tm of the magnetic layer 43 is 80 nm or less, when a ring-type head is used as the recording head, the influence of the demagnetizing field can be reduced, and further excellent electromagnetic conversion characteristics can be obtained.
  • the lower limit of the average thickness tm of the magnetic layer 43 is preferably 35 nm or more. If the lower limit of the average thickness tm of the magnetic layer 43 is 35 nm or more, output can be ensured when an MR head is used as the reproducing head, and therefore further excellent electromagnetic conversion characteristics can be obtained.
  • the average thickness t m of the magnetic layer 43 is obtained as follows. First, the magnetic tape 22 to be measured is processed by the FIB method or the like to be sliced. When the FIB method is used, a carbon layer and a tungsten layer are formed as protective films as a pretreatment for observing a TEM image of the cross section described later. The carbon layer is formed by a deposition method on the surface of the magnetic tape 22 on the magnetic layer 43 side and on the surface of the back layer 44 side, and the tungsten layer is further formed by a deposition method or a sputtering method on the surface on the magnetic layer 43 side. The slice is performed along the length direction (longitudinal direction) of the magnetic tape 22. That is, the slice forms a cross section parallel to both the longitudinal direction and the thickness direction of the magnetic tape 22.
  • TEM transmission electron microscope
  • the thickness of the magnetic layer 43 is measured at at least 10 positions in the longitudinal direction of the magnetic tape 22.
  • the obtained measurements are simply averaged (arithmetic average) to obtain an average value, which is defined as the average thickness t m [nm] of the magnetic layer 43. Note that the positions at which the above measurement is performed are selected at random from the test piece.
  • the magnetic powder includes a plurality of magnetic particles.
  • the magnetic particles are, for example, particles containing hexagonal ferrite (hereinafter referred to as “hexagonal ferrite particles”), particles containing epsilon-type iron oxide ( ⁇ iron oxide) (hereinafter referred to as “ ⁇ iron oxide particles”), or particles containing Co-containing spinel ferrite (hereinafter referred to as “cobalt ferrite particles”). It is preferable that the magnetic powder has a crystal orientation preferentially in the thickness direction (perpendicular direction) of the magnetic tape 22.
  • the hexagonal ferrite particles have a plate shape, such as a hexagonal plate shape.
  • the hexagonal slope shape includes an almost hexagonal slope shape.
  • the hexagonal ferrite preferably contains at least one of Ba, Sr, Pb and Ca, more preferably at least one of Ba and Sr.
  • the hexagonal ferrite may be, specifically, for example, barium ferrite or strontium ferrite.
  • the barium ferrite may further contain at least one of Sr, Pb and Ca in addition to Ba.
  • the strontium ferrite may further contain at least one of Ba, Pb and Ca in addition to Sr.
  • the hexagonal ferrite has an average composition represented by the general formula MFe12O19 .
  • M is, for example, at least one metal selected from Ba, Sr, Pb, and Ca, preferably at least one metal selected from Ba and Sr.
  • M may be a combination of Ba and one or more metals selected from the group consisting of Sr, Pb, and Ca.
  • M may also be a combination of Sr and one or more metals selected from the group consisting of Ba, Pb, and Ca.
  • a part of Fe may be substituted with another metal element.
  • the average particle size of the magnetic powder is preferably 13 nm to 22 nm, more preferably 13 nm to 19 nm, even more preferably 13 nm to 18 nm, particularly preferably 14 nm to 17 nm, and most preferably 14 nm to 16 nm.
  • the average particle size of the magnetic powder is 22 nm or less, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained in a high recording density magnetic tape 22.
  • the average particle size of the magnetic powder is 13 nm or more, the dispersibility of the magnetic powder is further improved, and even better electromagnetic conversion characteristics (e.g., SNR) can be obtained.
  • the average aspect ratio of the magnetic powder is preferably 1.0 or more and 3.0 or less, more preferably 1.3 or more and 2.8 or less, and even more preferably 1.6 or more and 2.7 or less.
  • the average aspect ratio of the magnetic powder is within the range of 1.0 or more and 2.5 or less, aggregation of the magnetic powder can be suppressed.
  • the magnetic powder is vertically oriented in the process of forming the magnetic layer 43, the resistance applied to the magnetic powder can be suppressed. Therefore, the vertical orientation of the magnetic powder can be improved.
  • the average particle size and average aspect ratio of the magnetic powder can be found as follows.
  • the magnetic tape 22 to be measured is processed and sliced by FIB or the like.
  • a carbon layer and a tungsten layer are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below.
  • the carbon layer is formed by deposition on the surface of the magnetic tape 22 on the magnetic layer 43 side and on the surface of the back layer 44 side, and the tungsten layer is further formed by deposition or sputtering on the surface on the magnetic layer 43 side.
  • the slice is performed along the length direction (longitudinal direction) of the magnetic tape 22. In other words, the slice forms a cross section parallel to both the longitudinal direction and the thickness direction of the magnetic tape 22.
  • the above-mentioned cross section of the obtained thin sample is observed using a transmission electron microscope (H-9500 manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV and a total magnification of 500,000 times so that the entire magnetic layer 43 is included in the thickness direction of the magnetic layer 43, and a TEM photograph is taken.
  • a transmission electron microscope H-9500 manufactured by Hitachi High-Technologies Corporation
  • 50 particles are selected that are oriented with their side facing the observation surface direction and whose thickness can be clearly confirmed.
  • the maximum plate thickness DA of each of the selected 50 particles whose thickness can be clearly confirmed is measured.
  • the maximum plate thickness DA thus obtained is simply averaged (arithmetic average) to obtain the average maximum plate thickness DA ave .
  • the plate diameter DB of each magnetic powder is measured.
  • the plate diameter DB of the particles 50 particles whose plate diameter can be clearly confirmed are selected from the TEM photograph taken.
  • the plate diameter DB of each of the selected 50 particles is measured.
  • the plate diameter DB thus obtained is simply averaged (arithmetic average) to obtain the average plate diameter DB ave .
  • the average plate diameter DB ave is the average particle size.
  • the average aspect ratio of the particles (DB ave /DA ave ) is calculated from the average maximum plate thickness DA ave and the average plate diameter DB ave .
  • the average particle volume of the magnetic powder is preferably 500 nm3 or more and 2500 nm3 or less, more preferably 500 nm3 or more and 1600 nm3 or less, even more preferably 500 nm3 or more and 1500 nm3 or less, particularly preferably 600 nm3 or more and 1200 nm3 or less, and most preferably 600 nm3 or more and 1000 nm3 or less.
  • the average particle volume of the magnetic powder is 2500 nm3 or less, the same effect as when the average particle size of the magnetic powder is 22 nm or less can be obtained.
  • the average particle volume of the magnetic powder is 500 nm3 or more, the same effect as when the average particle size of the magnetic powder is 13 nm or more can be obtained.
  • the average particle volume of the magnetic powder is calculated as follows. First, the average major axis length DA ave and the average plate diameter DB ave are calculated as described above in relation to the method for calculating the average particle size of the magnetic powder. Next, the average volume V of the magnetic powder is calculated using the following formula.
  • the ⁇ -iron oxide particles are hard magnetic particles that can obtain high coercivity even in the case of fine particles.
  • the ⁇ -iron oxide particles are spherical or cubic.
  • the term “spherical” includes “approximately spherical.”
  • the term “cubic” includes “approximately cubic.” Since the ⁇ -iron oxide particles have the above-mentioned shape, when the ⁇ -iron oxide particles are used as the magnetic particles, the contact area between the particles in the thickness direction of the magnetic tape 22 can be reduced and the aggregation between the particles can be suppressed compared to when hexagonal plate-shaped barium ferrite particles are used as the magnetic particles. Therefore, the dispersibility of the magnetic powder can be improved, and further excellent electromagnetic conversion characteristics (e.g., SNR) can be obtained.
  • SNR electromagnetic conversion characteristics
  • the ⁇ -iron oxide particles may have a composite particle structure. More specifically, the ⁇ -iron oxide particles include an ⁇ -iron oxide portion and a portion having soft magnetism or a portion having a higher saturation magnetization ⁇ s and a smaller coercive force Hc than ⁇ -iron oxide (hereinafter referred to as the "soft magnetic portion, etc.”).
  • the ⁇ -iron oxide portion contains ⁇ -iron oxide.
  • the ⁇ -iron oxide contained in the ⁇ -iron oxide portion preferably has ⁇ -Fe 2 O 3 crystals as a main phase, and more preferably is made of single-phase ⁇ -Fe 2 O 3 .
  • the soft magnetic portion is in contact with at least a portion of the ⁇ -iron oxide portion. Specifically, the soft magnetic portion may partially cover the ⁇ -iron oxide portion, or may cover the entire periphery of the ⁇ -iron oxide portion.
  • the soft magnetic portion (the magnetic portion having a higher saturation magnetization ⁇ s and a smaller coercive force Hc than ⁇ -iron oxide) includes, for example, a soft magnetic material such as ⁇ -Fe, a Ni-Fe alloy, or an Fe-Si-Al alloy.
  • ⁇ -Fe may be obtained by reducing the ⁇ -iron oxide contained in the ⁇ -iron oxide portion.
  • the portion having soft magnetic properties may contain, for example, Fe 3 O 4 , ⁇ -Fe 2 O 3 , or spinel ferrite.
  • the coercive force Hc of the ⁇ -iron oxide portion alone can be kept high to ensure thermal stability, while the coercive force Hc of the ⁇ -iron oxide particle (composite particle) as a whole can be adjusted to a coercive force Hc suitable for recording.
  • the ⁇ iron oxide particles may contain an additive instead of the structure of the composite particles, or may have the structure of the composite particles and contain an additive. In this case, part of the Fe in the ⁇ iron oxide particles is replaced with the additive.
  • the additive is a metal element other than iron, preferably a trivalent metal element, more preferably at least one selected from the group consisting of Al, Ga and In, and even more preferably at least one selected from the group consisting of Al and Ga.
  • the ⁇ -iron oxide containing the additive is an ⁇ -Fe2 - xMxO3 crystal (wherein M is a metal element other than iron, preferably a trivalent metal element, more preferably at least one selected from the group consisting of Al, Ga and In, and even more preferably at least one selected from the group consisting of Al and Ga; x is, for example, 0 ⁇ x ⁇ 1).
  • the average particle size (average maximum particle size) of the magnetic powder is, for example, 22 nm or less.
  • the average particle size (average maximum particle size) of the magnetic powder is preferably 20 nm or less, more preferably 8 nm to 20 nm, even more preferably 10 nm to 18 nm, particularly preferably 10 nm to 16 nm, and most preferably 10 nm to 14 nm.
  • the area with a size of 1/2 the recording wavelength becomes the actual magnetization area. Therefore, by setting the average particle size of the magnetic powder to half or less of the shortest recording wavelength, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained.
  • the average particle size of the magnetic powder is 22 nm or less, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained in a high recording density magnetic tape 22 (e.g., a magnetic tape 22 configured to be able to record signals at the shortest recording wavelength of 44 nm or less).
  • a high recording density magnetic tape 22 e.g., a magnetic tape 22 configured to be able to record signals at the shortest recording wavelength of 44 nm or less.
  • the average particle size of the magnetic powder is 8 nm or more, the dispersibility of the magnetic powder is further improved, and even better electromagnetic conversion characteristics (e.g., SNR) can be obtained.
  • the average aspect ratio of the magnetic powder is preferably 1.0 or more and 3.0 or less, more preferably 1.0 or more and 2.5 or less, even more preferably 1.0 or more and 2.1 or less, and particularly preferably 1.0 or more and 1.8 or less.
  • the average aspect ratio of the magnetic powder is within the range of 1.0 or more and 3.0 or less, aggregation of the magnetic powder can be suppressed.
  • the magnetic powder is vertically oriented in the process of forming the magnetic layer 43, the resistance applied to the magnetic powder can be suppressed. Therefore, the vertical orientation of the magnetic powder can be improved.
  • the average particle size and average aspect ratio of the magnetic powder can be found as follows.
  • the magnetic tape 22 to be measured is processed and sliced by FIB (Focused Ion Beam) method or the like.
  • FIB Flucused Ion Beam
  • a carbon layer and a tungsten layer are formed as protective layers as a pretreatment for observing the cross-sectional TEM image described below.
  • the carbon layer is formed by deposition on the surface of the magnetic tape 22 on the magnetic layer 43 side and the surface on the back layer 44 side, and the tungsten layer is further formed by deposition or sputtering on the surface on the magnetic layer 43 side.
  • the slices are formed along the length direction (longitudinal direction) of the magnetic tape 22. In other words, the slices form a cross section parallel to both the longitudinal direction and the thickness direction of the magnetic tape 22.
  • the above-mentioned cross section of the obtained thin sample is observed by using a transmission electron microscope (H-9500 manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV and a total magnification of 500,000 times so that the entire magnetic layer 43 is included in the thickness direction of the magnetic layer 43, and a TEM photograph is taken.
  • 50 particles whose particle shape can be clearly confirmed are selected from the TEM photograph taken, and the long axis length DL and short axis length DS of each particle are measured.
  • the long axis length DL means the maximum distance between two parallel lines drawn from all angles so as to be in contact with the contour of each particle (so-called maximum Feret diameter).
  • the short axis length DS means the maximum length of the particle in the direction perpendicular to the long axis (DL) of the particle.
  • the long axis lengths DL of the measured 50 particles are simply averaged (arithmetic average) to obtain the average long axis length DL ave .
  • the average long axis length DL ave thus obtained is the average particle size of the magnetic powder.
  • the minor axis lengths DS of the 50 particles are simply averaged (arithmetic mean) to determine the average minor axis length DSave .
  • the average aspect ratio of the particles ( DLave / DSave ) is then calculated from the average major axis length DLave and the average minor axis length DSave .
  • the average particle volume of the magnetic powder is preferably 5600 nm3 or less, more preferably 250 nm3 to 4200 nm3 , even more preferably 600 nm3 to 3000 nm3 , particularly preferably 600 nm3 to 2200 nm3 , and most preferably 600 nm3 to 1500 nm3 . Since the noise of the magnetic tape 22 is generally inversely proportional to the square root of the number of particles (i.e., proportional to the square root of the particle volume), further improved electromagnetic conversion characteristics (e.g., SNR) can be obtained by making the particle volume smaller.
  • SNR electromagnetic conversion characteristics
  • the average particle volume of the magnetic powder is 5600 nm3 or less, further improved electromagnetic conversion characteristics (e.g., SNR) can be obtained in the same way as when the average particle size of the magnetic powder is 22 nm or less.
  • the average particle volume of the magnetic powder is 250 nm3 or more, the same effect as when the average particle size of the magnetic powder is 8 nm or more can be obtained.
  • the average volume of the magnetic powder can be found as follows.
  • the magnetic tape 22 is processed and sliced by FIB (Focused Ion Beam) method or the like.
  • FIB Flucused Ion Beam
  • a carbon film and a tungsten thin film are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below.
  • the carbon film is formed by deposition on the surface of the magnetic tape 22 on the magnetic layer 43 side and on the surface of the back layer 44 side, and the tungsten thin film is further formed by deposition or sputtering on the surface on the magnetic layer 43 side.
  • the slices are formed along the length direction (longitudinal direction) of the magnetic tape 22. In other words, the slices form a cross section parallel to both the longitudinal direction and the thickness direction of the magnetic tape 22.
  • the obtained thin sample is observed in cross section in the thickness direction of the magnetic layer 43 with a transmission electron microscope (H-9500 manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV and a total magnification of 500,000 times, so that the entire magnetic layer 43 is included, and a TEM photograph is obtained.
  • the magnification and acceleration voltage may be appropriately adjusted depending on the type of device.
  • 50 particles whose particle shape is clear are selected from the TEM photograph taken, and the side length DC of each particle is measured.
  • the side lengths DC of the measured 50 particles are simply averaged (arithmetic average) to obtain the average side length DC ave .
  • the average volume V ave (particle volume) of the magnetic powder is calculated from the following formula using the average side length DC ave .
  • V ave DC ave 3
  • the cobalt ferrite particles preferably have uniaxial crystal anisotropy.
  • the cobalt ferrite particles have uniaxial crystal anisotropy, which allows the magnetic powder to be preferentially crystal-oriented in the thickness direction (vertical direction) of the magnetic tape 22.
  • the cobalt ferrite particles have, for example, a cubic shape. In this specification, the cubic shape includes an almost cubic shape.
  • the Co-containing spinel ferrite may further contain at least one of Ni, Mn, Al, Cu, and Zn in addition to Co.
  • the Co-containing spinel ferrite has, for example, an average composition represented by the following formula.
  • Co x M y Fe 2 O Z (In the formula, M is, for example, at least one metal selected from Ni, Mn, Al, Cu, and Zn.
  • x is a value within the range of 0.4 ⁇ x ⁇ 1.0.
  • y is a value within the range of 0 ⁇ y ⁇ 0.3.
  • x and y satisfy the relationship of (x+y) ⁇ 1.0.
  • z is a value within the range of 3 ⁇ z ⁇ 4.
  • a part of Fe may be substituted with another metal element.
  • the average particle size of the magnetic powder is 22 nm or less.
  • the average particle size (average maximum particle size) of the magnetic powder is preferably 20 nm or less, more preferably 8 nm to 20 nm, even more preferably 10 nm to 18 nm, particularly preferably 10 nm to 16 nm, and most preferably 10 nm to 14 nm.
  • the average particle size of the magnetic powder is 22 nm or less, it is possible to obtain even better electromagnetic conversion characteristics (e.g., SNR) in a high recording density magnetic tape 22.
  • the average particle size of the magnetic powder is 8 nm or more, the dispersibility of the magnetic powder is further improved, and it is possible to obtain even better electromagnetic conversion characteristics (e.g., SNR).
  • the method of calculating the average particle size of the magnetic powder is the same as the method of calculating the average particle size of the magnetic powder when the magnetic powder contains ⁇ iron oxide particles.
  • the average aspect ratio of the magnetic powder is preferably 1.0 or more and 3.0 or less, more preferably 1.0 or more and 2.5 or less, even more preferably 1.0 or more and 2.1 or less, and particularly preferably 1.0 or more and 1.8 or less.
  • the average aspect ratio of the magnetic powder is within the range of 1.0 or more and 3.0 or less, aggregation of the magnetic powder can be suppressed.
  • the magnetic powder is vertically oriented in the process of forming the magnetic layer 43, the resistance applied to the magnetic powder can be suppressed. Therefore, the vertical orientation of the magnetic powder can be improved.
  • the method of calculating the average aspect ratio of the magnetic powder is the same as the method of calculating the average aspect ratio of the magnetic powder when the magnetic powder contains ⁇ iron oxide particle powder.
  • the average particle volume of the magnetic powder is preferably 5600 nm3 or less, more preferably 250 nm3 to 4200 nm3 , even more preferably 600 nm3 to 3000 nm3 , particularly preferably 600 nm3 to 2200 nm3, and most preferably 600 nm3 to 1500 nm3 .
  • the average particle volume of the magnetic powder is 5600 nm3 or less, the same effect as when the average particle size of the magnetic powder is 25 nm or less can be obtained.
  • the average particle volume of the magnetic powder is 500 nm3 or more, the same effect as when the average particle size of the magnetic powder is 8 nm or more can be obtained.
  • the method of calculating the average particle volume of the magnetic component is the same as the method of calculating the average particle volume when the ⁇ iron oxide particles have a cubic shape.
  • binder examples include thermoplastic resins, thermosetting resins, and reactive resins.
  • thermoplastic resin examples include vinyl chloride, vinyl acetate, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylonitrile copolymers, acrylic acid ester-acrylonitrile copolymers, acrylic acid ester-vinyl chloride-vinylidene chloride copolymers, acrylic acid ester-acrylonitrile copolymers, acrylic acid ester-vinylidene chloride copolymers, methacrylic acid ester-vinylidene chloride copolymers, methacrylic acid ester-vinyl chloride copolymers, methacrylic acid ester-ethylene copolymers, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymers, acrylonitrile-butadiene copolymers, polyamide resins, polyvinyl fluoride, vinyliden
  • thermosetting resins examples include phenolic resins, epoxy resins, polyurethane curing resins, urea resins, melamine resins, alkyd resins, silicone resins, polyamine resins, and urea formaldehyde resins.
  • all of the above-mentioned binders may contain polar functional groups such as -SO 3 M, -OSO 3 M, -COOM, P ⁇ O(OM) 2 (wherein M represents a hydrogen atom or an alkali metal such as lithium, potassium, or sodium), side-chain amines having terminal groups represented by -NR1R2 or -NR1R2R3 + X - , and main-chain amines represented by >NR1R2 + X - (wherein R1, R2, and R3 represent a hydrogen atom or a hydrocarbon group, and X - represents a halogen element ion such as fluorine, chlorine, bromine, or iodine, an inorganic ion, or an organic ion), -OH, -SH, -CN, and an epoxy group.
  • the amount of these polar functional groups introduced into the binder is preferably 10 -1 to 10 -8 mol/g, and more preferably
  • the lubricant contains at least one selected from, for example, fatty acids and fatty acid esters, preferably both fatty acids and fatty acid esters.
  • the inclusion of a lubricant in the magnetic layer 43 contributes to improving the running stability of the magnetic tape 22. More particularly, the magnetic layer 43 contains a lubricant and has pores, thereby achieving good running stability. The improvement in running stability is believed to be due to the lubricant adjusting the dynamic friction coefficient of the magnetic layer 43 side surface of the magnetic tape 22 to a value suitable for running the magnetic tape 22.
  • the fatty acid may preferably be a compound represented by the following general formula (1) or (2).
  • the fatty acid may contain either a compound represented by the following general formula (1) or a compound represented by the following general formula (2), or may contain both.
  • the fatty acid ester may preferably be a compound represented by the following general formula (3) or (4).
  • the fatty acid ester may contain either a compound represented by the following general formula (3) or a compound represented by the following general formula (4), or may contain both.
  • the lubricant contains either or both of a compound represented by general formula (1) and a compound represented by general formula (2), and either or both of a compound represented by general formula (3) and a compound represented by general formula (4), thereby making it possible to suppress an increase in the dynamic friction coefficient of the magnetic tape 22 due to repeated recording or playback.
  • k is an integer selected from the range of 14 to 22, more preferably from the range of 14 to 18.
  • Antistatic Agent examples include carbon black, natural surfactants, nonionic surfactants, and cationic surfactants.
  • abrasive examples include acicular ⁇ -iron oxide obtained by dehydrating and annealing raw materials such as ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, silicon carbide, chromium oxide, cerium oxide, ⁇ -iron oxide, corundum, silicon nitride, titanium carbide, titanium oxide, silicon dioxide, tin oxide, magnesium oxide, tungsten oxide, zirconium oxide, boron nitride, zinc oxide, calcium carbonate, calcium sulfate, barium sulfate, molybdenum disulfide, and magnetic iron oxide, and if necessary, those obtained by surface-treating these with aluminum and/or silica.
  • raw materials such as ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, silicon carbide, chromium oxide, cerium oxide, ⁇ -iron oxide, corundum, silicon nitride, titanium carbide, titanium oxide, silicon dioxide, tin oxide, magnesium oxide, tungsten oxide, zi
  • Examples of the curing agent include polyisocyanates.
  • Examples of the polyisocyanates include aromatic polyisocyanates such as an adduct of tolylene diisocyanate (TDI) and an active hydrogen compound, and aliphatic polyisocyanates such as an adduct of hexamethylene diisocyanate (HMDI) and an active hydrogen compound.
  • the weight average molecular weight of these polyisocyanates is preferably in the range of 100 to 3,000.
  • anti-rust examples include phenols, naphthols, quinones, heterocyclic compounds containing a nitrogen atom, heterocyclic compounds containing an oxygen atom, and heterocyclic compounds containing a sulfur atom.
  • Non-magnetic reinforcing particles examples include aluminum oxide ( ⁇ , ⁇ or ⁇ alumina), chromium oxide, silicon oxide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, titanium oxide (rutile or anatase type titanium oxide), and the like.
  • the underlayer 42 serves to reduce the unevenness of the surface of the substrate 41 and adjust the unevenness of the surface of the magnetic layer 43.
  • the underlayer 42 is a non-magnetic layer containing non-magnetic powder, a binder, and a lubricant.
  • the underlayer 42 supplies the lubricant to the surface of the magnetic layer 43.
  • the underlayer 42 may further contain at least one additive selected from the group consisting of an antistatic agent, a hardener, and an anti-rust agent, as necessary.
  • the average thickness of the underlayer 42 is preferably 0.3 ⁇ m or more and 2.0 ⁇ m or less, and more preferably 0.5 ⁇ m or more and 1.4 ⁇ m or less.
  • the average thickness of the underlayer 42 is determined in the same manner as the average thickness of the magnetic layer 43. However, the magnification of the TEM image is adjusted appropriately according to the thickness of the underlayer 42. If the average thickness of the underlayer 42 is 2.0 ⁇ m or less, the elasticity of the magnetic tape 22 due to external forces becomes even higher, making it even easier to adjust the width of the magnetic tape 22 by adjusting the tension.
  • the non-magnetic powder includes at least one of inorganic particle powder and organic particle powder.
  • the non-magnetic powder may also include carbon powder such as carbon black.
  • One type of non-magnetic powder may be used alone, or two or more types of non-magnetic powder may be used in combination.
  • the inorganic particles include, for example, metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, metal sulfides, etc.
  • the shape of the non-magnetic powder may be, for example, various shapes such as needle-like, spherical, cubic, and plate-like, but is not limited to these shapes.
  • Binding agent, lubricant The binder and lubricant are the same as those in the magnetic layer 43 described above.
  • the antistatic agent, hardener and anticorrosive agent are the same as those in the magnetic layer 43 described above.
  • the back layer 44 contains a binder and a non-magnetic powder.
  • the back layer 44 may further contain at least one additive selected from the group consisting of a lubricant, a hardener, and an antistatic agent, if necessary.
  • the binder and the non-magnetic powder are the same as those of the underlayer 42 described above.
  • the average particle size of the non-magnetic powder is preferably 10 nm or more and 150 nm or less, more preferably 15 nm or more and 110 nm or less.
  • the average particle size of the non-magnetic powder is determined in the same manner as the average particle size of the magnetic powder described above.
  • the non-magnetic powder may contain non-magnetic powder having two or more particle size distributions.
  • the upper limit of the average thickness of the back layer 44 is preferably 0.6 ⁇ m or less. If the upper limit of the average thickness of the back layer 44 is 0.6 ⁇ m or less, the thickness of the underlayer 42 and the substrate 41 can be kept thick even when the average thickness of the magnetic tape 22 is 5.6 ⁇ m or less, so that the running stability of the magnetic tape 22 within the recording and reproducing device can be maintained.
  • the lower limit of the average thickness of the back layer 44 is not particularly limited, but is, for example, 0.2 ⁇ m or more.
  • the back layer 44 has a surface on which numerous protrusions are provided.
  • the numerous protrusions are intended to form numerous holes in the surface of the magnetic layer 43 when the magnetic tape 22 is wound into a roll.
  • the numerous holes are composed of, for example, numerous non-magnetic particles protruding from the surface of the back layer 44.
  • the upper limit of the average thickness (average total thickness) t T of the magnetic tape 22 is 5.4 ⁇ m or less, preferably 5.2 ⁇ m or less, more preferably 5.1 ⁇ m or less, and even more preferably 5.0 ⁇ m or less.
  • the lower limit of the average thickness t T of the magnetic tape 22 is not particularly limited, but is, for example, 4.5 ⁇ m or more.
  • the total length of the magnetic tape 22 is 1000 m or more.
  • the average thickness t T of the magnetic tape 22 is obtained as follows. First, a 1/2 inch wide magnetic tape 22 is prepared and cut into a length of 250 mm to prepare a sample. Next, using a Mitutoyo Laser Hologram (LGH-110C) as a measuring device, the thickness of the sample is measured at five or more positions, and the measured values are simply averaged (arithmetic mean) to calculate the average value t T [ ⁇ m]. Note that the measurement positions are selected randomly from the sample.
  • LGH-110C Mitutoyo Laser Hologram
  • the upper limit of the coercive force Hc2 of the magnetic layer 43 in the longitudinal direction of the magnetic tape 22 is preferably 2000 Oe or less, more preferably 1900 Oe or less, and even more preferably 1800 Oe or less. If the coercive force Hc2 of the magnetic layer 43 in the longitudinal direction is 2000 Oe or less, sufficient electromagnetic conversion characteristics can be obtained even at high recording density.
  • the lower limit of the coercive force Hc2 of the magnetic layer 43 measured in the longitudinal direction of the magnetic tape 22 is preferably 1000 Oe or more. If the coercive force Hc2 of the magnetic layer 43 measured in the longitudinal direction is 1000 Oe or more, demagnetization due to leakage flux from the recording head can be suppressed.
  • the coercive force Hc2 is obtained as follows. First, three sheets of the magnetic tape 22 are stacked with double-sided tape, and then punched out with a ⁇ 6.39 mm punch to prepare a measurement sample. At this time, marking is performed with any non-magnetic ink so that the longitudinal direction (running direction) of the magnetic tape 22 can be identified. Then, the M-H loop of the measurement sample (whole magnetic tape 22) corresponding to the longitudinal direction (running direction) of the magnetic tape 22 is measured using a vibrating sample magnetometer (VSM). Next, the coating film (undercoat layer 42, magnetic layer 43, back layer 44, etc.) is wiped off using acetone or ethanol, etc., leaving only the substrate 41.
  • VSM vibrating sample magnetometer
  • correction sample a sample for background correction (hereinafter simply referred to as "correction sample”. Then, the MH loop of the correction sample (substrate 41) corresponding to the perpendicular direction of the substrate 41 (perpendicular direction of the magnetic tape 22) is measured using a VSM.
  • VSM-P7-15 type manufactured by Toei Industry Co., Ltd.
  • the measurement conditions are as follows: measurement mode: full loop, maximum magnetic field: 15 kOe, magnetic field step: 40 bits, time constant of locking amp: 0.3 sec, waiting time: 1 sec, number of MH averages: 20.
  • background correction is performed by subtracting the M-H loop of the correction sample (substrate 41) from the M-H loop of the measurement sample (entire magnetic tape 22), and the M-H loop after background correction is obtained.
  • the measurement and analysis program included with the "VSM-P7-15" is used for this background correction calculation.
  • the coercive force Hc2 is obtained from the obtained M-H loop after background correction. Note that the measurement and analysis program included with the "VSM-P7-15" is used for this calculation. Note that all of the above M-H loop measurements are performed at 25°C. Also, no "demagnetization field correction" is performed when measuring the M-H loop in the longitudinal direction of the magnetic tape 22.
  • the squareness ratio S1 of the magnetic layer 43 in the perpendicular direction (thickness direction) of the magnetic tape 22 is preferably 65% or more, more preferably 70% or more, even more preferably 75% or more, particularly preferably 80% or more, and most preferably 85% or more. If the squareness ratio S1 is 65% or more, the perpendicular orientation of the magnetic powder is sufficiently high, so that even better electromagnetic conversion characteristics (e.g., SNR) can be obtained.
  • SNR electromagnetic conversion characteristics
  • the squareness ratio S1 in the vertical direction is obtained as follows. First, three magnetic tapes 22 are stacked with double-sided tape, and then punched with a ⁇ 6.39 mm punch to prepare a measurement sample. At this time, marking is performed with any non-magnetic ink so that the longitudinal direction (running direction) of the magnetic tape 22 can be recognized. Then, the MH loop of the measurement sample (whole magnetic tape 22) corresponding to the vertical direction (thickness direction) of the magnetic tape 22 is measured using a VSM. Next, the coating film (undercoat layer 42, magnetic layer 43, back layer 44, etc.) is wiped off using acetone or ethanol, etc., leaving only the substrate 41.
  • VSM-P7-15 type manufactured by Toei Industry Co., Ltd.
  • the measurement conditions are as follows: measurement mode: full loop, maximum magnetic field: 15 kOe, magnetic field step: 40 bits, time constant of locking amp: 0.3 sec, waiting time: 1 sec, number of MH averages: 20.
  • background correction is performed by subtracting the M-H loop of the correction sample (substrate 41) from the M-H loop of the measurement sample (entire magnetic tape 22), thereby obtaining the M-H loop after background correction.
  • the measurement and analysis program included with the "VSM-P7-15" is used to calculate this background correction.
  • the squareness ratio S2 of the magnetic layer 43 in the longitudinal direction (running direction) of the magnetic tape 22 is preferably 35% or less, more preferably 30% or less, even more preferably 25% or less, particularly preferably 20% or less, and most preferably 15% or less. If the squareness ratio S2 is 35% or less, the magnetic powder will have a sufficiently high vertical orientation, making it possible to obtain even better electromagnetic conversion characteristics (e.g., SNR).
  • the squareness ratio S2 in the longitudinal direction is determined in the same manner as the squareness ratio S1, except that the M-H loop is measured in the longitudinal direction (running direction) of the magnetic tape 22 and the substrate 41.
  • the surface roughness Rb of the back surface is Rb ⁇ 6.0 [nm].
  • the surface roughness Rb of the back surface is in the above range, even better electromagnetic conversion characteristics can be obtained.
  • [Tape drive device] 5 is a plan view showing a schematic configuration of a tape drive device 100 for recording and/or reproducing data from the tape cartridge 1. As shown in FIG.
  • the tape drive device 100 includes a mounting section 101, a loading mechanism (not shown) that pulls out the magnetic tape 22 from the tape cartridge 1 mounted in the mounting section 101, a take-up reel 102 that winds up the magnetic tape 22 pulled out by the loading mechanism, a number of guide rollers 103a, 103b, 103c, 103d that form a tape path between the tape cartridge 1 and the take-up reel 102 and guide the running of the magnetic tape 22, and a magnetic head 104 as a head section that is disposed opposite the magnetic surface of the magnetic tape 22.
  • the tape drive device 100 rotates the take-up reel 102 in the tape winding direction and the tape rewinding direction, while using the magnetic head 104 to record information onto the magnetic tape 22 or reproduce information recorded on the magnetic tape 22.
  • full-height drive devices that are used in large-scale libraries
  • half-height drive devices that are half the height of full-height drive devices are also known as tape drive devices.
  • Full-height and half-height tape drive devices differ only in height, and there is no significant difference in the performance of recording and reproducing information from tape cartridges, so currently, users use them according to their operating environment.
  • the relative position of the tape to the magnetic head may fluctuate due to factors such as an unavoidable decrease in linearity during the manufacturing process of the magnetic tape and a decrease in the geometric precision of the take-up reel inside the tape drive device, which may interfere with the normal recording or reproducing operation of information by the magnetic head.
  • Figure 6 shows the results of an experiment that shows the relationship between the tape length and the magnitude of the position error signal (PES: Position Error Signal) of the data track when information is recorded on magnetic tape using a half-height tape drive.
  • FWD indicates the magnetic tape feed direction (the direction in which the magnetic tape is wound from the tape reel of the tape cartridge to the take-up reel of the tape drive)
  • RVS indicates the magnetic tape rewind direction (the direction in which the magnetic tape is wound from the take-up reel of the tape drive to the tape reel of the tape cartridge).
  • the tape drive divides the entire length of the magnetic tape into 80 regions (Regions: RGN) and acquires data, and the horizontal axis in the figure indicates the region (RGN) number.
  • the average total thickness of the magnetic tape used was 5.2 ⁇ m, and the substrate was made of PET (polyethylene terephthalate) with a thickness of 4.0 ⁇ m.
  • the loop stiffness of this magnetic tape in the MD direction was 1.5 mg/ ⁇ m, and the loop stiffness in the TD (width direction of the tape) was 1.6 mg/ ⁇ m.
  • this magnetic tape will also be referred to as the magnetic tape relating to the comparative example.
  • the PES is almost uniform over the entire length of the tape in the forward direction (FWD) of the magnetic tape, whereas in the rewind direction (RVS), the PES fluctuates significantly over a 50 RGN (80 RGN-30 RGN) interval from the start of the rewind operation.
  • capacity loss the probability of data write failure occurring for the maximum recording capacity of this magnetic tape
  • the hub of the take-up reel 102 is a molded body made of synthetic resin material formed integrally with the lower flange, and it is believed that these protrusions were unavoidably generated due to molding defects such as sink marks. Then, as a result of the magnetic tape 22 being wound in layers on top of these protrusions, the magnetic tape 22 was deformed, which is thought to have caused the position error during running as described above to increase and the capacitance loss to worsen.
  • the magnetic tape 22 is not always straight, and may be slightly curved, for example, due to reasons associated with the cutting process of the magnetic tape 22 to the product width.
  • the magnetic tape 22 can be curved in two directions, negative and positive.
  • the negative curvature direction refers to the magnetic tape 22 curving in a direction that convexly curves toward the lower flange 102a of the take-up reel 102
  • the positive curvature direction refers to the magnetic tape 22 curving in a direction that convexly curves toward the upper flange 102b of the take-up reel 102.
  • the magnetic tape unwound from the tape reel 5 of the tape cartridge 1 is wound onto the take-up reel 102 of the tape drive device 100 while repeatedly moving up and down.
  • the magnetic tape 22 will be wound around the reel hub 102c toward the lower flange 102a, and the tape edge on the opposite side will tend to deform due to contact with the inner surface of the lower flange 102a.
  • the magnetic tape 22 when the curvature direction of the magnetic tape 22 is positive, the magnetic tape 22 is more likely to be wound around the reel hub 102c with the tape edge in contact with the lower flange 102a side as shown diagrammatically in FIG. 9(B), and is generally stably wound around the area of the lower part of the hub 102c (the lower flange 102a side).
  • the curvature direction of the magnetic tape 22 when the curvature direction of the magnetic tape 22 is positive, deformation of the tape edge is suppressed compared to when the curvature direction is negative, making it possible to reduce capacity loss, but it is preferable to minimize tape damage due to contact with the lower flange 102a.
  • the tape cartridge 1 of this embodiment has a magnetic tape 22 and tape reel 5 configured as follows.
  • the magnetic tape 22 has a substrate 41 and a magnetic layer 43 provided on one main surface of the substrate 41, the substrate 41 is made of polyethylene naphthalate (PEN), the total thickness of the magnetic tape 22 is 4.9 ⁇ m or more and 5.4 ⁇ m or less, and the loop stiffness in the width direction of the magnetic tape 22 is 1.1 mg/ ⁇ m or more and 1.4 mg/ ⁇ m or less.
  • the tape width of the magnetic tape 22 is 12.65 mm.
  • PEN has a higher tensile strength and Young's modulus than PET. Therefore, PEN substrate 41 has the characteristic of being more rigid and less prone to deformation than a PET substrate formed to the same thickness.
  • PEN substrate 41 may be a uniaxially stretched film or a biaxially stretched film.
  • magnetic tape 22 with a PEN substrate 41 has a smaller amount of deformation of magnetic tape 22 even when minute protrusions such as those described above are present on the outer peripheral surface of the hub of take-up reel 102 of tape drive device 100, making it less likely that winding abnormalities will occur on take-up reel 102.
  • the loop stiffness in the TD direction of the PEN substrate 41 is preferably 1.1 mg/ ⁇ m or more and 1.4 mg/ ⁇ m or less. If the loop stiffness exceeds 1.4 mg/ ⁇ m, the rigidity of the substrate 41 becomes too high, which inhibits deformation of the tape edge when it comes into contact with the upper flange or the lower flange, making the tape more susceptible to damage. Furthermore, if the loop stiffness is less than 1.1 mg/ ⁇ m, sufficient rigidity cannot be ensured, making it difficult to achieve the desired effect.
  • the total thickness (average total thickness) of the magnetic tape 22 is preferably 4.9 ⁇ m or more and 5.4 ⁇ m or less.
  • the Young's modulus in the width direction of the magnetic tape 22 is set to 7.8 GPa/ mm2 .
  • the loop stiffness in the width direction of the magnetic tape 22 can be measured in accordance with ECMA-319 Standard 9.16 Bending stiffness (JIS X 6175 (2006) page 38).
  • the longitudinal shrinkage rate of the magnetic tape 22 when stored at 70°C for 48 hours is 0.1% or less. This makes it difficult for the width of the magnetic tape 22 to fluctuate due to temperature, etc. (for example, even under a long-term accelerated deterioration environment such as one month at 45°C). Therefore, off-track can be prevented, and data can be accurately recorded on the magnetic tape 22, or data recorded on the magnetic tape 22 can be accurately reproduced.
  • the longitudinal shrinkage rate may be 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, etc.
  • the TDS (Transverse Dimensional Stability) of the magnetic tape 22 is an index for evaluating the dimensional stability of the magnetic tape 22 in the width direction, and is expressed as an absolute value of the rate of change in the dimension of the magnetic tape 22 in the width direction.
  • causes of dimensional change in the width direction include (1) changes in tape distortion due to aging, (2) changes due to temperature and humidity, and (3) changes due to drive tension while the tape is running.
  • the smaller the TDS value the higher the dimensional stability in the width direction.
  • a reference width of the magnetic tape 22 is determined, and the tension of the magnetic tape 22 is adjusted so that the width of the magnetic tape 22 becomes the reference value during data recording/playback.
  • the magnetic tape 22 configured as described above preferably has a positive curvature direction. This allows the magnetic tape 22 to be stably wound around the area of the lower part (lower flange 102a side) of the hub 102c of the take-up reel 102 as shown in FIG. 9(B). This makes it possible to reduce deformation of the tape edge and reduce capacity loss compared to when the curvature direction is negative.
  • the substrate 41 is made of PEN as described above, it is less susceptible to the influence of minute protrusions present on the outer peripheral surface of the hub 102c, and deformation of the magnetic tape 22 and winding abnormalities on the take-up reel 102 caused by the influence of the minute protrusions can be suppressed.
  • the magnitude of the curvature of the magnetic tape 22 is set to a deviation of 3.8 mm or less from the chord of a length of 1 m of the magnetic tape 22. If the deviation exceeds 3.8 mm, the curvature becomes too strong and deformation of the tape edge cannot be suppressed.
  • FIG. 10 is a schematic side view of the tape reel 5 of the present embodiment.
  • the tape reel 5 has a reel hub 6, a lower flange 7 as a first flange, and an upper flange 8 as a second flange.
  • the lower flange 7 is integrally formed with the lower end (first end) of the reel hub 6, and the upper flange 8 is joined to the upper end (second end) of the reel hub 6 by ultrasonic bonding or the like.
  • the reel hub 6 has a generally cylindrical shape, and its axial height is approximately 13 mm, which is slightly larger than the width (12.65 mm) of the magnetic tape 22.
  • the inner diameter of the reel hub 6 is approximately 40 mm (39.6 mm), and its radial thickness is approximately 2 mm.
  • the reel hub 6 and the lower flange 7 are integrally molded using synthetic resin materials such as PC (polycarbonate) and ABS (acrylonitrile butadiene styrene).
  • the upper flange 8 is also molded using synthetic resin materials such as PC and ABS.
  • the molding material for the reel hub 6 and the lower flange 7 may be a composite material in which an inorganic filler such as glass filler is added to the above synthetic resin material for the purpose of improving strength.
  • the weight ratio of the glass filler is not particularly limited, and is, for example, about 10% to 30% by weight of the base synthetic resin material. In this embodiment, a composite material containing 10% to 20% by weight of glass filler in polycarbonate resin is used as the molding material for the reel hub 6.
  • d1 outer diameter of the lower flange 7 and the upper flange 8): 96.80 mm
  • d2 (the diameter of the hub 6) is 44.00 mm ⁇ 0.10 mm
  • OD1 distance from the inside of the upper flange 8 to the reference plane P at the outer diameter d1: 14.905 mm ⁇ 0.075 mm
  • ID1 distance from the inside of the upper flange 8 to the reference plane P at diameter d2): 14.82 mm ⁇ 0.04 mm OD2 (distance from the inside of the lower flange 7 to the reference plane P at the outer diameter d1): 1.78 mm ⁇ 0.12 mm
  • the reference plane P is the plane defined by the pitch line of the hub teeth (chucking gear 9 in Fig. 1(B)) at a diameter of 37.50 mm, and is the position that is 1/2 the distance from the imaginary tip to the bottom of the tooth (ECMA-319 Standard 8.6.6 Reel hubs (JIS X 6175 (2006) page 14)).
  • Table 1 shows the differences in dimensions of the above-mentioned parts between the tape reel used in the experimental example shown in Figure 6 (a tape reel wound with a magnetic tape relating to the comparative example; hereinafter, also referred to as the tape reel relating to the comparative example) and the tape reel 5 of this embodiment.
  • the inner surface of the upper flange 8 and the inner surface of the lower flange 7 of the tape reel 5 are formed with tapered surfaces that open toward the outer periphery of the reel, making it difficult for the edges of the magnetic tape 22 to come into contact with the flanges while the tape is running.
  • the distance OD1 and the distance ID1 of the tape reel 5 are set lower than those of the tape reel of the comparative example. Therefore, the flange outer diameter d1 and the distances HG1 and HG2 between the two flanges at the diameter d2 of the hub 6 are shorter than those of the tape reel of the comparative example (the flange spacing is narrower).
  • the minimum value of the distance along the axial direction of the hub 6 between the lower flange 7 and the upper flange 8 is 12.96 mm ⁇ 0.20 mm in the comparative example while it is 12.9 mm ⁇ 0.14 mm in this embodiment
  • the maximum value of the above distance is 13.24 mm ⁇ 0.24 mm in the comparative example while it is 13.125 mm ⁇ 0.195 mm in this embodiment.
  • HG1 when expressed relative to the tape width (12.65 mm) of the magnetic tape 22, in the comparative example, HG1 is 1.03 to 1.07 times the tape width and HG2 is 1.01 to 1.04 times the tape width, whereas in this embodiment, HG1 is 1.02 to 1.05 times the tape width and HG2 is 1.01 to 1.03 times the tape width.
  • the taper amount of the upper flange (the difference in height between the inner and outer periphery of the upper flange) in the tape reel of the comparative example is 0.1 mm to 0.14 mm, whereas the taper amount of the upper flange in this embodiment is approximately 0.05 mm.
  • the regulating effect on the running position of the magnetic tape 22 unwound from the tape reel 5 is stronger than in the tape reel of the comparative example, so the vertical movement of the magnetic tape 22 while it runs is small. Therefore, according to this embodiment, the magnetic tape 22 is wound onto the take-up reel 102 of the tape drive device 100 at a stable height position, so the amount of deformation of the tape edge due to contact with the upper and lower flanges of the take-up reel 102 can be reduced.
  • the base material of the magnetic tape 22 is formed from PEN, which provides greater rigidity than the magnetic tape of the comparative example, which has a base material made from PET. This makes it possible to further reduce the amount of deformation of the tape edge due to contact with the upper and lower flanges of the take-up reel 102. Furthermore, as described above, even if there are minute protrusions on the outer peripheral surface of the hub of the take-up reel 102, deformation of the magnetic tape 22 due to the minute protrusions can be suppressed, thereby suppressing the occurrence of winding abnormalities of the magnetic tape 22 on the take-up reel 102.
  • the inventors evaluated the capacitance loss of the magnetic tape by recording and reproducing predetermined data over the entire length of the magnetic tape for the tape cartridge according to the comparative example and the tape cartridge 1 of the present embodiment.
  • the tape drive device used in the experiment was a half-height tape drive device (model number: TS2290) manufactured by IBM.
  • a capacity loss defect was determined when the data write defective area was below a specified capacity (17.4 TB or less (uncompressed) in this example) out of the total recording capacity of the magnetic tape 22 per tape cartridge (45 TB for LTO9 (18 TB uncompressed)), and the number of such defective areas was counted.
  • the method for determining whether or not there was a capacity loss defect was to repeat full volume write only five times for the total recording capacity of the magnetic tape 22 (45 TB for LTO9 (18 TB uncompressed)), and if the area where data was successfully written all five times was 17.4 TB (uncompressed) or more, it was determined that there was no capacity loss, and if it fell below 17.4 TB (uncompressed) even once, it was determined that there was capacity loss.
  • the number of turns with defective capa loss in the tape cartridge according to the comparative example was 4 out of 22 turns, whereas the number of turns with defective capa loss in the tape cartridge according to this embodiment was 0 out of 16 turns.
  • the rigidity of the magnetic tape 22 is increased, thereby making it possible to increase the resistance of the tape edge to deformation caused by contact with the flange of the take-up reel of the tape drive device or by small protrusions present on the outer circumferential surface of the hub.
  • the running position of the magnetic tape 22 unwound from the tape reel 5 can be regulated, thereby suppressing winding abnormalities on the take-up reel. As a result, the PES characteristics during recording and playback of the magnetic tape 22 are improved, and the occurrence of capacitance loss in the magnetic tape 22 can be suppressed.
  • the present technology can also be configured as follows.
  • a magnetic tape having a substrate and a magnetic layer provided on one main surface of the substrate,
  • the substrate is made of polyethylene naphthalate (PEN),
  • PEN polyethylene naphthalate
  • the total thickness of the magnetic tape is 4.9 ⁇ m or more and 5.4 ⁇ m or less
  • the magnetic tape has a loop stiffness in a width direction of 1.1 mg/ ⁇ m or more and 1.4 mg/ ⁇ m or less.
  • the magnetic tape according to (1) a non-magnetic layer provided between the substrate and the magnetic layer; A back layer provided on the other main surface of the substrate.
  • the magnetic tape according to (1) or (2) The magnetic tape, wherein the thickness of the substrate is 4.2 ⁇ m or less.
  • a tape reel including a first flange, a second flange, and a cylindrical reel hub having a first end integrally formed with the first flange and a second end to which the second flange is joined; a magnetic tape having a substrate and a magnetic layer provided on one main surface of the substrate and wound around an outer circumferential surface of the reel hub;
  • the substrate is made of polyethylene naphthalate (PEN),
  • PEN polyethylene naphthalate
  • the total thickness of the magnetic tape is 4.9 ⁇ m or more and 5.4 ⁇ m or less,
  • the magnetic tape has a loop stiffness in a width direction of 1.1 mg/ ⁇ m or more and 1.4 mg/ ⁇ m or less.
  • the tape cartridge according to (10) above, the magnetic tape is curved in a shape that is convex toward the second flange side, and the deviation from a chord of 1 m of the magnetic tape is 3.8 mm or less.
  • an inner surface of the first flange and an inner surface of the second flange are formed as tapered surfaces that open toward an outer periphery of the tape reel.
  • a tape cartridge, wherein the minimum distance between the first flange and the second flange along the axial direction of the hub is 12.9 mm ⁇ 0.14 mm.
  • the tape cartridge according to (12) or (13) above, A tape cartridge, wherein a maximum distance between the first flange and the second flange along the axial direction of the hub is 13.125 mm ⁇ 0.195 mm.

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