JP2020173884A - Magnetic recording medium and cartridge - Google Patents

Abstract

To provide a magnetic recording medium capable of minimizing deterioration in reproduction reliability.SOLUTION: A magnetic tape MT provided herein is a tape-shaped magnetic recording medium comprising a recording layer 43, a base layer 42, a substrate 41, and a back layer, and has an average thickness tT that satisfies 3.5 [μm]≤tT≤5.5 [μm], and exhibits a dimensional change Δw in a width direction thereof, associated with a change in tension in a longitudinal direction thereof, that satisfies 700 [ppm/N]≤Δw≤20000 [ppm/N].SELECTED DRAWING: Figure 4

Description

The present disclosure relates to magnetic recording media and cartridges.

In recent years, in magnetic tapes (tape-shaped magnetic recording media) used as data storage for computers, the track width and the distance between adjacent tracks have become extremely narrow in order to improve the data recording density. When the track width and the distance between tracks are narrowed in this way, the maximum allowable change amount of the tape itself due to environmental factors such as temperature and humidity changes becomes smaller and smaller.

For this reason, Patent Document 1 proposes a magnetic tape medium capable of suppressing dimensional changes in the width direction due to environmental factors to a small extent and ensuring stable recording / reproduction characteristics with less off-track. Further, Patent Document 1 describes that the amount of dimensional change in the width direction with respect to the tension change in the longitudinal direction is reduced.

Japanese Unexamined Patent Publication No. 2005-332510

In recent years, the number of recording tracks has increased and the width of recording tracks has become narrower due to the demand for larger capacities of magnetic tapes. For this reason, if the width of the magnetic tape fluctuates even slightly after the data is recorded on the magnetic tape, the recording / playback device cannot accurately reproduce the data recorded on the magnetic tape. An error may occur. That is, the reliability of reproduction may decrease.

An object of the present disclosure is to provide a magnetic recording medium and a cartridge capable of suppressing a decrease in reproduction reliability.

In order to solve the above-mentioned problems, the first disclosure is
A tape-shaped magnetic recording medium including a recording layer, a base layer, a substrate, and a back layer.
The average thickness t _T of the magnetic recording medium is 3.5 [μm] ≤ t _T ≤ 5.5 [μm].
This is a magnetic recording medium in which the amount of dimensional change Δw in the width direction of the magnetic recording medium with respect to the tension change in the longitudinal direction of the magnetic recording medium is 700 [ppm / N] ≦ Δw ≦ 20000 [ppm / N].

The second disclosure is
The magnetic recording medium of the first disclosure and
Cartridge case and
Cartridge memory and
Including reels
The magnetic recording medium is a cartridge housed in the cartridge case in a state of being wound on the reel.

It is the schematic which shows an example of the structure of the recording / reproduction system which concerns on 1st Embodiment of this disclosure. It is an exploded perspective view which shows an example of the structure of a cartridge. It is a block diagram which shows an example of the structure of a cartridge memory. It is sectional drawing which shows an example of the structure of a magnetic tape. FIG. 5A is a schematic diagram of the layout of the data band and the servo band. FIG. 5B is an enlarged view of the data band. It is a perspective view which shows the structure of the measuring apparatus. It is a flowchart for demonstrating an example of operation of a recording / reproduction apparatus at the time of data recording. It is a flowchart for demonstrating an example of operation of a recording / reproduction apparatus at the time of data reproduction. It is the schematic which shows an example of the structure of the recording / reproduction system which concerns on the 2nd Embodiment of this disclosure. It is a flowchart for demonstrating an example of operation of a recording / reproduction apparatus at the time of data recording. It is a flowchart for demonstrating an example of operation of a recording / reproduction apparatus at the time of data reproduction.

The embodiments of the present disclosure will be described in the following order. In all the drawings of the following embodiments, the same or corresponding parts are designated by the same reference numerals.
1 1st embodiment 2 2nd embodiment 3 Modified example

<1 First Embodiment>
[Overview]
The present inventors are studying a magnetic tape suitable for use in a recording / playback device capable of keeping the width of the magnetic tape constant or substantially constant by adjusting the tension in the longitudinal direction of the magnetic tape. Further, it is conceivable to adjust the tension by using the tension adjustment information stored in advance in the cartridge memory. However, according to the findings of the present inventors, as described above, a general magnetic tape has a small amount of dimensional change in the width direction with respect to a tension change in the longitudinal direction, so that the width of the magnetic tape can be adjusted by the recording / playback device. It is difficult to keep it constant or nearly constant.

Therefore, the present inventors have diligently studied a magnetic tape capable of keeping the width of the magnetic tape constant or substantially constant by the recording / reproducing device. As a result, contrary to the above-mentioned general magnetic tape, the magnetic tape in which the amount of dimensional change in the width direction with respect to the tension change in the longitudinal direction is increased, specifically, the amount of dimensional change in the width direction with respect to the tension change in the longitudinal direction Δw. We have come up with a magnetic tape in which 650 [ppm / N] ≦ Δw.

[Recording / playback system configuration]
FIG. 1 is a schematic view showing an example of the configuration of the recording / reproducing system 100 according to the embodiment of the present disclosure. The recording / playback system 100 is a magnetic tape recording / playback system, and includes a cartridge 10 and a recording / playback device 50 configured so that the cartridge 10 can be loaded and unloaded.

[Cartridge configuration]
FIG. 2 is an exploded perspective view showing an example of the configuration of the cartridge 10. The cartridge 10 is a magnetic tape cartridge conforming to the LTO (Linear Tape-Open) standard, and is a magnetic tape (tape-shaped magnetic recording medium) inside a cartridge case 12 composed of a lower shell 12A and an upper shell 12B. It straddles the reel 13 on which the MT is wound, the reel lock 14 and the reel spring 15 for locking the rotation of the reel 13, the spider 16 for releasing the locked state of the reel 13, and the lower shell 12A and the upper shell 12B. A slide door 17 for opening and closing the tape outlet 12C provided on the cartridge case 12, a door spring 18 for urging the slide door 17 to the closed position of the tape outlet 12C, and a light protect 19 for preventing erroneous erasure. And a cartridge memory 11. The reel 13 has a substantially disk shape having an opening in the center, and is composed of a reel hub 13A and a flange 13B made of a hard material such as plastic. A leader pin 22 is provided at one end of the magnetic tape MT.

The cartridge memory 11 is provided in the vicinity of one corner of the cartridge 10. In a state where the cartridge 10 is loaded in the recording / reproducing device 50, the cartridge memory 11 faces the reader / writer 57 of the recording / reproducing device 50. The cartridge memory 11 communicates with the recording / reproducing device 50, specifically, the reader / writer 57, in a wireless communication standard compliant with the LTO standard.

[Cartridge memory configuration]
FIG. 3 is a block diagram showing an example of the configuration of the cartridge memory 11. The cartridge memory 11 generates a power source by generating and rectifying using an induced electromotive force from an antenna coil (communication unit) 31 that communicates with the reader / writer 57 according to a specified communication standard and radio waves received by the antenna coil 31. The rectification / power supply circuit 32, the clock circuit 33 that also uses the induced electromotive force to generate a clock from the radio waves received by the antenna coil 31, the detection of the radio waves received by the antenna coil 31, and the signal transmitted by the antenna coil 31. A controller (control unit) 35 composed of a detection / modulation circuit 34 that performs modulation and a logic circuit or the like for discriminating commands and data from the digital signals extracted from the detection / modulation circuit 34 and processing them. , A memory (storage unit) 36 for storing information is provided. Further, the cartridge memory 11 includes a capacitor 37 connected in parallel to the antenna coil 31, and the antenna coil 31 and the capacitor 37 form a resonance circuit.

The memory 36 stores information and the like related to the cartridge 10. The memory 36 is a non-volatile memory (NVM). The storage capacity of the memory 36 is preferably about 32 KB or more.

The memory 36 has a first storage area 36A and a second storage area 36B. The first storage area 36A corresponds to the storage area of the LTO standard cartridge memory before LTO 8 (hereinafter referred to as “conventional cartridge memory”), and is used for storing information conforming to the LTO standard before LTO 8. The area. Information conforming to the LTO standard before LTO 8 is, for example, manufacturing information (for example, the unique number of the cartridge 10), usage history (for example, the number of tape withdrawals (Thread Count), etc.) and the like.

The second storage area 36B corresponds to an extended storage area with respect to the storage area of the conventional cartridge memory. The second storage area 36B is an area for storing additional information. Here, the additional information means information related to the cartridge 10 which is not defined by the LTO standard before LTO8. Examples of the additional information include, but are not limited to, tension adjustment information, management ledger data, index information, thumbnail information of moving images stored in the magnetic tape MT, and the like. The tension adjustment information includes the distance between adjacent servo bands (distance between servo patterns recorded in the adjacent servo bands) when data is recorded on the magnetic tape MT. The distance between adjacent servo bands is an example of width-related information related to the width of the magnetic tape MT. The details of the distance between the servo bands will be described later. In the following description, the information stored in the first storage area 36A may be referred to as "first information", and the information stored in the second storage area 36B may be referred to as "second information".

The memory 36 may have a plurality of banks. In this case, a first storage area 36A may be formed by a part of the plurality of banks, and a second storage area 36B may be formed by the remaining banks. Specifically, for example, the memory 36 has two banks having a storage capacity of about 16 KB, one of the two banks constitutes the first storage area 36A, and the other bank constitutes the second. The storage area 36B may be configured.

The antenna coil 31 induces an induced voltage by electromagnetic induction. The controller 35 communicates with the recording / reproducing device 50 according to a specified communication standard via the antenna coil 31. Specifically, for example, mutual authentication, command transmission / reception, data exchange, etc. are performed.

The controller 35 stores the information received from the recording / reproducing device 50 via the antenna coil 31 in the memory 36. The controller 35 reads information from the memory 36 and transmits the information to the recording / reproducing device 50 via the antenna coil 31 in response to the request of the recording / reproducing device 50.

[Structure of magnetic tape]
FIG. 4 is a cross-sectional view showing an example of the configuration of the magnetic tape MT used in the cartridge 10. The magnetic tape MT is, for example, a magnetic tape of a perpendicular magnetic recording system, and is a long base 41, a base layer (non-magnetic layer) 42 provided on one main surface of the base 41, and a base layer 42. It includes a recording layer (magnetic layer) 43 provided on the top and a back layer 44 provided on the other main surface of the substrate 41. The base layer 42 and the back layer 44 are provided as needed, and may be omitted. In the following, of the two main surfaces of the magnetic tape MT, the surface on the side where the recording layer 43 is provided is referred to as a magnetic surface, and the surface on the opposite side where the back layer 44 is provided is referred to as a back surface. There is.

The magnetic tape MT has a long shape and runs in the longitudinal direction during recording and reproduction. Further, the magnetic tape MT is configured to be capable of recording a signal at the shortest recording wavelength of preferably 100 nm or less, more preferably 75 nm or less, still more preferably 60 nm or less, and particularly preferably 50 nm or less. For example, the shortest recording wavelength is It is used for recording / playback devices within the above range. This recording / reproducing device may include a ring-shaped head as a recording head.

(Hypokeimenon)
The substrate 41 serving as a support is a flexible, long, non-magnetic substrate. The substrate 41 is a film, and the average thickness T _sub of the substrate 41 is preferably 3 μm or more and 8 μm or less, more preferably 3 μm or more and 4.2 μm or less, still more preferably 3 μm or more and 3.8 μm or less, and particularly preferably 3 μm or more 3 It is 0.4 μm or less.

The average thickness T _sub of the substrate 41 is obtained as follows. First, a 1/2 inch wide magnetic tape MT is prepared and cut into a length of 250 mm to prepare a sample. Subsequently, the layers other than the substrate 41 of the sample (that is, the base layer 42, the recording 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 laser holo gauge manufactured by Mitutoyo as a measuring device, the thickness of the sample (base 41) is measured at 5 or more points, and the measured values are simply averaged (arithmetic mean) to make the base 41. The average thickness T _{sub of} is calculated. The measurement position shall be randomly selected from the sample.

The substrate 41 contains, for example, at least one of polyesters, polyolefins, cellulose derivatives, vinyl resins, aromatic polyetherketones (PAEKs), and other polymer resins. When the substrate 41 contains two or more of the above materials, the two or more materials may be mixed, copolymerized, or laminated.

Examples of polyesters include PET (polyethylene terephthalate), PEN (polyethylene terephthalate), PBT (polybutylene terephthalate), PBN (polybutylene terephthalate), PCT (polycyclohexylene methylene terephthalate), and PEB (polyethylene-p- It contains at least one of oxybenzoate) and polyethylene bisphenoxycarboxylate.

Polyolefins include, for example, at least one of PE (polyethylene) and PP (polypropylene). Cellulose derivatives include, for example, at least one of cellulose diacetate, cellulose triacetate, CAB (cellulose acetate butyrate) and CAP (cellulose acetate propionate). The vinyl resin contains, for example, at least one of PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride). Aromatic polyetherketones (PAEKs) include, for example, polyetheretherketones (PEEKs).

Other polymer resins include, for example, PA (polyamide, nylon), aromatic PA (aromatic polyamide, aramid), PI (polyimide), aromatic PI (aromatic polyimide), PAI (polyamideimide), aromatic PAI. (Aromatic polyamideimide), PBO (polybenzoxazole, eg, Zyrone®), polyether, PEK (polyetherketone), polyether ester, PES (polyethersulfon), PEI (polyetherimide), It contains at least one of PSF (polysulphon), PPS (polyphenylene sulfide), PC (polyamide), PAR (polyamide) and PU (polyimide).

(Recording layer)
The recording layer 43 is a so-called perpendicular recording layer and contains, for example, magnetic powder and a binder. If necessary, the recording layer 43 may further contain one or more additives selected from the group consisting of lubricants, conductive particles, abrasives, rust preventives, and the like.

The recording layer 43 has a surface provided with a large number of holes, and it is preferable that a lubricant is stored in these a large number of holes. As a result, friction due to contact between the magnetic tape MT and the head can be reduced. The large number of holes preferably extend perpendicular to the surface of the recording layer 43. This is because the supply of the lubricant to the surface of the recording layer 43 can be improved. It should be noted that a part of a large number of holes may be extended in the vertical direction.

The average thickness t _m of the recording layer 43 is preferably 35 [nm] ≤ t _m ≤ 90 [nm], more preferably 35 [nm] ≤ t _m ≤ 80 [nm], and even more preferably 35 [nm] ≤ t _m ≤ 70 [nm], particularly preferably 35 [nm] ≤ t _m ≤ 50 [nm]. When the average thickness t _m of the recording layer 43 is 35 [nm] ≦ t _m , the output can be secured when the MR type head is used as the reproduction head, so that the electromagnetic conversion characteristics can be improved. On the other hand, when the average thickness t _m of the recording layer 43 is t _m ≤ 90 [nm], the influence of the demagnetic field can be reduced when the ring type head is used as the recording head, so that the electromagnetic conversion characteristics can be improved. Can be done.

The average thickness t _m of the recording layer 43 is obtained as follows. First, the magnetic tape MT is thinly processed perpendicular to its main surface to prepare a sample piece, and the cross section of the sample piece is observed with a transmission electron microscope (TEM) under the following conditions. Do.
Equipment: TEM (H9000NAR manufactured by Hitachi, Ltd.)
Acceleration voltage: 300kV
Magnification: 100,000 times Next, using the obtained TEM image, the thickness of the recording layer 43 is measured at at least 10 points or more in the longitudinal direction of the magnetic tape MT, and then the measured values are simply averaged ( Arithmetic mean) to give the average thickness of the recording layer 43 t _m (nm).

As shown in FIG. 5A, the recording layer 43 preferably has a plurality of servo band SBs and a plurality of data band DBs in advance. The plurality of servo bands SB are provided at equal intervals in the width direction of the magnetic tape MT. A data band DB is provided between adjacent servo bands SB. A servo signal for controlling the tracking of the magnetic head is written in advance in the servo band SB. User data is recorded in the data band DB by the recording / playback device 50.

The upper limit of the ratio R _S (= (S _SB / S) × 100) of the total area S _SB of the servo band SB to the surface area S of the recording layer 43 is preferably 4. from the viewpoint of ensuring a high recording capacity. It is 0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. On the other hand, the lower limit of the ratio R _S of the total area S _SB of the servo band SB to the surface area S of the recording layer 43 is preferably 0.8% or more from the viewpoint of securing a servo track of 5 or more.

The ratio R _S of the total area S _SB of the servo band SB to the surface area S of the recording layer 43 is obtained as follows. First, the surface of the recording layer 43 is observed using a magnetic force microscope (MFM), and an MFM image is acquired. Subsequently, the number of servo bandwidth W _SB and servo band SB is measured using the acquired MFM image. Next, the ratio R _S is calculated from the following formula.
Ratio _{R S [%] = ((} ( servo bandwidth W _SB) × (the number of servo bands SB)) / (width of the magnetic tape MT)) × 100

The lower limit of the number of servo band SBs is preferably 5 or more, more preferably 5 + 4n (where n is a positive integer) or more, and even more preferably 9 + 4n or more. When the number of servo band SBs is 5 or more, it is possible to suppress the influence on the servo signal due to the dimensional change in the width direction of the magnetic tape MT and secure stable recording / playback characteristics with less off-track. The upper limit of the number of servo band SBs is not particularly limited, but is, for example, 33 or less.

The number of servo band SBs can be confirmed as follows. First, the surface of the recording layer 43 is observed using a magnetic force microscope (MFM) to obtain an MFM image. Next, the number of servo band SBs is counted using the MFM image.

The upper limit of the servo bandwidth W _SB is preferably 95 μm or less, more preferably 60 μm or less, and even more preferably 30 μm or less from the viewpoint of ensuring a high recording capacity. The lower limit of the servo bandwidth W _SB is preferably 10 μm or more. It is difficult to manufacture a recording head capable of reading a servo signal having a servo bandwidth of less than 10 μm W _SB .

The servo bandwidth W _SB is obtained as follows. First, the surface of the recording layer 43 is observed using a magnetic force microscope (MFM) to obtain an MFM image. Next, the servo bandwidth W _SB is measured using the MFM image.

As shown in FIG. 5B, the recording layer 43 is configured so that a plurality of data tracks Tk can be formed in the data band DB. The total number of data tracks Tk that can be formed on the recording layer 43 is preferably 6000 or more from the viewpoint of ensuring a high recording capacity. The upper limit of the data track width W is preferably 3.0 μm or less, more preferably 1.6 μm or less, still more preferably 0.95 μm or less, particularly from the viewpoint of improving the track recording density and ensuring a high recording capacity. It is preferably 0.51 μm or less. The lower limit of the data track width W is preferably 0.02 μm or more in consideration of the magnetic particle size.

In the recording layer 43, the minimum value L of the magnetization reversal distance and the data track width W are preferably W / L ≦ 200, more preferably W / L ≦ 60, still more preferably W / L ≦ 45, and particularly preferably W. Data can be recorded so that / L ≦ 30. When the minimum value L of the magnetization reversal distance is a constant value and the minimum value L of the magnetization reversal distance and the track width W are W / L> 200 (that is, when the track width W is large), the track recording density increases. Therefore, there is a risk that sufficient recording capacity cannot be secured. Further, when the track width W is a constant value and the minimum value L of the magnetization reversal distance and the track width W are W / L> 200 (that is, when the minimum value L of the magnetization reversal distance is small), the bit length. However, the line recording density may increase, but the SNR may be significantly deteriorated due to the influence of the spacing loss. Therefore, in order to suppress the deterioration of SNR while securing the recording capacity, it is preferable that W / L is in the range of W / L ≦ 60 as described above. However, W / L is not limited to the above range, and may be W / L ≦ 23 or W / L ≦ 13. The lower limit of W / L is not particularly limited, but is, for example, 1 ≦ W / L.

From the viewpoint of ensuring a high recording capacity, the recording layer 43 has a minimum value L of the magnetization reversal distance of preferably 50 nm or less, more preferably 48 nm or less, still more preferably 44 nm or less, and particularly preferably 40 nm or less. , The data can be recorded. The lower limit of the minimum value L of the distance between magnetization reversals is preferably 20 nm or more in consideration of the magnetic particle size.

(Magnetic powder)
The magnetic powder includes powder of nanoparticles containing ε-iron oxide (hereinafter referred to as “ε-iron oxide particles”). The ε iron oxide particles are hard magnetic particles capable of obtaining a high coercive force even with fine particles. It is preferable that the ε-iron oxide contained in the ε-iron oxide particles is preferentially crystal-oriented in the thickness direction (vertical direction) of the magnetic tape MT.

The ε-iron oxide particles have a spherical or substantially spherical shape, or have a cubic or almost cubic shape. Since the ε-iron oxide particles have the above-mentioned shape, when the ε-iron oxide particles are used as the magnetic particles, the magnetic tape MT is compared with the case where the hexagonal plate-shaped barium ferrite particles are used as the magnetic particles. It is possible to reduce the contact area between the particles in the thickness direction of the particles and suppress the aggregation of the particles. Therefore, it is possible to improve the dispersibility of the magnetic powder and obtain a better SNR (Signal-to-Noise Ratio).

The ε iron oxide particles have a core-shell type structure. Specifically, the ε-iron oxide particles include a core portion and a shell portion having a two-layer structure provided around the core portion. The shell portion having a two-layer structure includes a first shell portion provided on the core portion and a second shell portion provided on the first shell portion.

The core part contains ε iron oxide. The iron oxide contained in the core portion preferably has ε-Fe ₂ O ₃ crystals as the main phase, and more preferably one composed of single-phase ε-Fe ₂ O ₃ .

The first shell portion covers at least a part of the periphery of the core portion. Specifically, the first shell portion may partially cover the periphery of the core portion, or may cover the entire periphery of the core portion. From the viewpoint of making the exchange coupling between the core portion and the first shell portion sufficient and improving the magnetic characteristics, it is preferable to cover the entire surface of the core portion.

The first shell portion is a so-called soft magnetic layer, and contains, for example, a soft magnetic material such as α-Fe, Ni-Fe alloy or Fe-Si-Al alloy. α-Fe may be obtained by reducing ε-iron oxide contained in the core portion.

The second shell portion is an oxide film as an antioxidant layer. The second shell portion contains α-iron oxide, aluminum oxide or silicon oxide. The α-iron oxide contains, for example, at least one iron oxide of Fe ₃ O ₄ , Fe ₂ O ₃ and Fe O. When the first shell portion contains α-Fe (soft magnetic material), the α-iron oxide may be obtained by oxidizing α-Fe contained in the first shell portion.

Since the ε iron oxide particles have the first shell portion as described above, the coercive force Hc of the core portion alone is maintained at a large value in order to ensure thermal stability, and the entire ε iron oxide particles (core shell particles) are maintained. The coercive force Hc can be adjusted to a coercive force Hc suitable for recording. Further, since the ε-iron oxide particles have the second shell portion as described above, the ε-iron oxide particles are exposed to the air in the manufacturing process of the magnetic tape MT and before the process, and the surface of the particles is rusted or the like. It is possible to suppress the deterioration of the characteristics of the ε iron oxide particles due to the occurrence of. Therefore, deterioration of the characteristics of the magnetic tape MT can be suppressed.

The average particle size (average maximum particle size) of the magnetic powder is, for example, 22.5 nm or less. The average particle size (average maximum particle size) of the magnetic powder is preferably 22 nm or less, more preferably 8 nm or more and 22 nm or less, still more preferably 12 nm or more and 22 nm or less, particularly preferably 12 nm or more and 15 nm or less, and most preferably 12 nm or more and 14 nm. It is as follows. In the magnetic tape MT, a region having a size of 1/2 of the recording wavelength is the actual magnetization region. Therefore, good electromagnetic conversion characteristics (for example, SNR) can be obtained by setting the average particle size of the magnetic powder to half or less of the shortest recording wavelength. Therefore, when the average particle size of the magnetic powder is 22 nm or less, good electromagnetic conversion characteristics are obtained in a high recording density magnetic tape MT (for example, a magnetic tape MT configured to be able to record a signal at the shortest recording wavelength of 44 nm or less). (For example, SNR) can be obtained. On the other hand, when the average particle size of the magnetic powder is 8 nm or more, the dispersibility of the magnetic powder is further improved, and more excellent electromagnetic conversion characteristics (for example, 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, still more preferably 1.0 or more and 2.1 or less, and particularly preferably 1.0. It is 1.8 or less. When the average aspect ratio of the magnetic powder is in the range of 1.0 or more and 3.0 or less, aggregation of the magnetic powder can be suppressed. Further, when the magnetic powder is vertically oriented in the step of forming the recording 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 above magnetic powder are obtained as follows. First, the magnetic tape MT to be measured is processed by the FIB (Focused Ion Beam) method or the like to prepare flakes, and the cross section of the flakes is observed by TEM. Next, 50 ε-iron oxide particles are randomly selected from the photographed TEM photographs, and the major axis length DL and minor axis length DS of each ε iron oxide particle are measured. Here, the major 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 the ε iron oxide particles (so-called maximum ferret diameter). On the other hand, the minor axis length DS means the maximum length of the ε iron oxide particles in the direction orthogonal to the major axis of the ε iron oxide particles.

Subsequently, the semimajor axis DL of the measured 50 ε iron oxide particles is simply averaged (arithmetic mean) to obtain the average semimajor axis DLave. The average major axis length DLave thus obtained is taken as the average particle size of the magnetic powder. Further, the average minor axis length DSave is obtained by simply averaging (arithmetic mean) the minor axis length DS of the measured 50 ε iron oxide particles. Then, the average aspect ratio (DLave / DSave) of the ε iron oxide particles is obtained from the average major axis length DLave and the average minor axis length DSave.

The average particle volume of the magnetic powder is preferably 5600Nm ³ or less, more preferably 250 nm ³ or more 5600Nm ³ or less, still more preferably 900 nm ³ or more 5600Nm ³ or less, particularly preferably 900 nm ³ or more 1800 nm ³ or less, and most preferably 900 nm ³ It is 1500 nm ³ or less. In general, the noise of the magnetic tape MT is inversely proportional to the square root of the number of particles (that is, proportional to the square root of the particle volume), so that good electromagnetic conversion characteristics (for example, SNR) can be obtained by making the particle volume smaller. .. Therefore, when the average particle volume of the magnetic powder is 5600 nm ³ or less, good electromagnetic conversion characteristics (for example, SNR) can be obtained with the same effect as when the average particle size of the magnetic powder is 22 nm or less. On the other hand, when the average particle volume of the magnetic powder is 250 nm ³ or more, the same effect as when the average particle size of the magnetic powder is 8 nm or more can be obtained.

When the ε iron oxide particles have a spherical shape or a substantially spherical shape, the average particle volume of the magnetic powder can be obtained as follows. First, the average major axis length DLave is obtained in the same manner as the above method for calculating the average particle size of the magnetic powder. Next, the average particle volume V of the magnetic powder is obtained by the following formula.
V = (π / 6) × DLave ³

When the ε iron oxide particles have a cubic shape or a substantially cubic shape, the average particle volume of the magnetic powder can be obtained as follows. First, the magnetic tape MT to be measured is processed by the FIB method or the like to prepare flakes, and the cross section of the flakes is observed by TEM. Subsequently, 50 ε-iron oxide particles having a plane parallel to the TEM cross section are randomly selected from the photographed TEM photographs, and the length L of one side of each ε-iron oxide particle is measured. Next, the length L of one side of the 50 measured iron oxide particles is simply averaged (arithmetic mean) to obtain the average side length Lave.
V = Love ³

(Binder)
As the binder, a resin having a structure in which a cross-linking reaction is applied to a polyurethane resin, a vinyl chloride resin, or the like is preferable. However, the binder is not limited to these, and other resins may be appropriately blended depending on the physical properties required for the magnetic tape MT. The resin to be blended is not particularly limited as long as it is a resin generally used in a coating type magnetic tape MT.

For example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, acrylic acid ester-chloride. Vinyl-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-chloride Vinyl copolymer, methacrylic acid ester-ethylene copolymer, polyfluorinated vinyl, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cellulose die) Acetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene butadiene copolymer, polyester resin, amino resin, synthetic rubber and the like.

Examples of the thermosetting resin or reactive resin include phenol resin, epoxy resin, urea resin, melamine resin, alkyd resin, silicone resin, polyamine resin, urea formaldehyde resin and the like.

Further, in each of the above-mentioned binders, polar functional groups such as -SO ₃ M, -OSO ₃ M, -COOM, and P = O (OM) ₂ are introduced for the purpose of improving the dispersibility of the magnetic powder. May be. Here, M in the formula is a hydrogen atom or an alkali metal such as lithium, potassium, or sodium.

Further, as the polar functional group, -NR1R2, -NR1R2R3 ⁺ X ^- as the side chain type having an end group of,> NR1R2 ⁺ X ^- include those of the main chain type. Here, R1, R2, and R3 in the formula are hydrogen atoms or hydrocarbon groups, and X ^- is a halogen element ion such as fluorine, chlorine, bromine, or iodine, or an inorganic or organic ion. Further, examples of the polar functional group include -OH, -SH, -CN, and an epoxy group.

(Additive)
The recording layer 43 has aluminum oxide (α, β or γ alumina), chromium oxide, silicon oxide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, titanium oxide (titanium carbide) as non-magnetic reinforcing particles. It may further contain rutile-type or anatase-type titanium oxide) and the like.

(Underground layer)
The base layer 42 is a so-called non-magnetic layer and contains, for example, a non-magnetic powder and a binder. The base layer 42 may further contain one or more additives selected from the group consisting of conductive particles, lubricants, curing agents, rust preventives, and the like, if necessary.

The average thickness t _u of the base layer 42 is preferably 0.6μm or more 2.0μm or less, more preferably 0.8μm or 1.4μm below. The average thickness t _u of the base layer 42 is obtained in the same manner as the average thickness t _m of the recording layer 43. However, the magnification of the TEM image is appropriately adjusted according to the thickness of the base layer 42.

(Non-magnetic powder)
The non-magnetic powder may be an inorganic substance or an organic substance. Further, the non-magnetic powder may be carbon black or the like. Examples of the inorganic substance include metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, metal sulfides and the like. Examples of the shape of the non-magnetic powder include, but are not limited to, various shapes such as needle shape, spherical shape, cube shape, and plate shape.

(Binder)
The binder is the same as the recording layer 43 described above.

(Back layer)
The back layer 44 contains a binder and a non-magnetic powder. The back layer 44 may contain various additives such as a lubricant, a curing agent and an antistatic agent, if necessary. The binder and the non-magnetic powder are the same as those of the above-mentioned base layer 42.

The average particle size of the inorganic particles is preferably 10 nm or more and 150 nm or less, and more preferably 15 nm or more and 110 nm or less. The average particle size of the inorganic particles is obtained in the same manner as the average particle size D of the magnetic powder described above.

The average thickness t _b of the back layer 44 is preferably t _b ≦ 0.6 [μm]. When the average thickness t _b of the back layer 44 is within the above range, the thickness of the base layer 42 and the base 41 is kept thick even when the average thickness t _T of the magnetic tape MT is set to t _T ≤ 5.5 [μm]. This makes it possible to maintain the running stability of the magnetic tape MT in the recording / playback device.

The average thickness t _b of the back layer 44 is obtained as follows. First, a 1/2 inch wide magnetic tape MT is prepared and cut into a length of 250 mm to prepare a sample. Next, using a laser holo gauge manufactured by Mitutoyo as a measuring device, the thicknesses of different places of the sample are measured at 5 points or more, and the measured values are simply averaged (arithmetic mean) to obtain an average thickness t _T [μm. ] Is calculated. Subsequently, the back layer 44 of the sample is removed with a solvent such as MEK (methyl ethyl ketone), dilute hydrochloric acid, or the like, and then the thickness of different parts of the sample is measured again at 5 points or more using the above laser holo gauge, and these measured values are measured. Is simply averaged (arithmetic mean) to calculate the average thickness t _B [μm]. Then, the average thickness t _b (μm) of the back layer 44 is obtained from the following formula.
t _b [μm] = t _T [μm] -t _B [μm]

(Average thickness of magnetic tape t _T )
The average thickness t _T of the magnetic tape MT is t _T ≤ 5.5 [μm], preferably t _T ≤ 5.2 [μm], more preferably t _T ≤ 5.0 [μm], and even more preferably t. _T ≤ 4.6 [μm], particularly preferably t _T ≤ 4.4 [μm]. When the average thickness t _T of the magnetic tape MT is t _T ≦ 5.5 [μm], the recording capacity that can be recorded in one data cartridge can be increased as compared with the conventional case. The lower limit of the average thickness t _T of the magnetic tape MT is not particularly limited, but is, for example, 3.5 [μm] ≤ t _T.

The average thickness t _T of the magnetic tape MT is obtained in the same manner as the average thickness t _T of the average thickness t _b of the back layer 44.

(Dimensional change amount Δw)
The amount of dimensional change Δw [ppm / N] in the width direction of the magnetic tape MT with respect to the tension change in the longitudinal direction of the magnetic tape MT is 650 ppm / N ≦ Δw, preferably 670 ppm / N ≦ Δw, and more preferably 680 ppm. / N ≦ Δw, even more preferably 700 ppm / N ≦ Δw, particularly preferably 750 ppm / N ≦ Δw, and most preferably 800 ppm / N ≦ Δw. When the amount of dimensional change Δw is Δw <650 ppm / N, it may be difficult to suppress the change in the width of the magnetic tape MT by adjusting the tension in the longitudinal direction of the magnetic tape MT by the recording / reproducing device 50. The upper limit of the amount of dimensional change Δw is not particularly limited, but is, for example, Δw ≦ 1700000 ppm / N, preferably Δw ≦ 20000 ppm / N, more preferably Δw ≦ 8000 ppm / N, and even more preferably Δw ≦ 5000 ppm / N. , Δw ≦ 4000 ppm / N, Δw ≦ 3000 ppm / N, or Δw ≦ 2000 ppm / N.

The amount of dimensional change Δw can be set to a desired value by selecting the substrate 41. For example, the amount of dimensional change Δw can be set to a desired value by selecting at least one of the thickness of the base 41 and the material of the base 41. Further, the dimensional change amount Δw may be set to a desired value, for example, by adjusting the stretching strength in the width direction and the longitudinal direction of the substrate 41. For example, by stretching the base 41 more strongly in the width direction, the dimensional change amount Δw is further reduced, and conversely, by strengthening the stretching of the base 41 in the longitudinal direction, the dimensional change amount Δw is increased.

（但し、式中、Ｄ（０．２Ｎ）およびＤ（１．０Ｎ）はそれぞれ、サンプル１０Ｓの長手方向に０．２Ｎおよび１．０Ｎの荷重をかけたときのサンプル１０Ｓの幅を示す。） The amount of dimensional change Δw is obtained as follows. First, a 1/2 inch wide magnetic tape MT is prepared and cut into a length of 250 mm to prepare a sample 10S. Next, loads are applied in the order of 0.2N, 0.6N, and 1.0N in the longitudinal direction of the sample 10S, and the width of the sample 10S under the loads of 0.2N, 0.6N, and 1.0N is measured. Subsequently, the amount of dimensional change Δw is obtained from the following equation. The measurement when a load of 0.6N is applied is performed to confirm that no abnormality has occurred in the measurement (especially to confirm that these three measurement results are linear). The measurement result is not used in the following formula.

(However, in the formula, D (0.2N) and D (1.0N) indicate the width of the sample 10S when a load of 0.2N and 1.0N is applied in the longitudinal direction of the sample 10S, respectively.)

The width of the sample 10S when each load is applied is measured as follows. First, the measuring device shown in FIG. 6 incorporating the digital dimension measuring device LS-7000 manufactured by KEYENCE is prepared as the measuring device, and the sample 10S is set in the measuring device. Specifically, one end of the long sample (magnetic tape MT) 10S is fixed by the fixing portion 231. Next, as shown in FIG. 6, the sample 10S is placed on _five substantially columnar and rod-shaped support members 232 _{1 to} 2325. Samples 10S, the back surface is in contact with the support member 232 _{1-232 5} of five, are placed on these support members 232 _{1 to 232 5.} The five support members 232 _{1 to} 232 ₅ (particularly their surfaces) are all made of stainless steel SUS304, and their surface roughness Rz (maximum height) is 0.15 μm to 0.3 μm.

The arrangement of the _five rod-shaped support members 232 _{1 to} 232 ₅ will be described with reference to FIG. As shown in FIG. 6, the sample 10S is placed on _five support members 232 _{1 to} 2325. Regarding the _five support members 232 _{1 to} 232 ₅ , in the following, "first support member 232 ₁ ", "second support member 232 ₂ ", and "third support member 232 ₃ " (from the one closest to the fixing portion 231) ( (Has a slit 232A), "fourth support member 232 ₄ ", and "fifth support member 232 ₅ " (closest to the weight 233). The diameters of these five first to fifth support members 232 _{1 to} 232 ₅ are all 7 mm. The distance d1 between the first support member 232 ₁ and the second support member 232 ₂ (particularly, the distance between the central axes of these support members) is 20 mm. The distance d2 between the second support member 232 ₂ and the third support member 232 ₃ is 30 mm. The distance d3 between the third support member 232 ₃ and the fourth support member 232 ₄ is 30 mm. The distance d4 between the fourth support member 232 ₄ and the fifth support member 232 ₅ is 20 mm.

Further, in the sample 10S, the portion of the sample 10S that sits between the second support member 232 ₂ , the third support member 232 ₃ , and the fourth support member 232 ₄ forms a plane substantially perpendicular to the direction of gravity. , These three support members 232 _{2 to} 232 ₄ are arranged. Further, the sample 10S is, between the first support member 232 ₁ and the second support member 232 _2, so as to form an angle .theta.1 = 30 ° to the plane of the substantially vertical, the first support member 232 ₁ and the second support member 232 ₂ is arranged. Further, the fourth support member 232 is formed so that the sample 10S forms an angle of θ2 = 30 ° with respect to the above-mentioned substantially vertical plane between the fourth support member 232 ₄ and the fifth support member 232 _{5. fourth} and fifth support member 232 ₅ is arranged. Further, of the five first to fifth support members 232 _{1 to} 232 ₅ , the third support member 232 ₃ is fixed so as not to rotate, but the other four first, second, and fourth support members are fixed. , Fifth support member 232 ₁ , 232 ₂ , 232 ₄ , 232 ₅ are all rotatable.

Samples 10S is held so as not to move in the width direction of the sample 10S on the support member 232 _{1-232 5.} Among the supporting members 232 _{1 to 232 5,} located between the light emitter 234 and light receiver 235, and a slit 232A is a support member 232 ₃ is located in the approximate center of the portion to apply a fixing portion 231 load Is provided. Light L is emitted from the light emitter 234 to the light receiver 235 via the slit 232A. The slit width of the slit 232A is 1 mm, and the light L can pass through the slit 232A without being blocked by the frame of the slit 232A.

Subsequently, after the measuring device is housed in a chamber controlled under a constant environment of a temperature of 25 ° C. and a relative humidity of 50%, a weight 233 for applying a load of 0.2 N is attached to the other end of the sample 10S, and the sample is sampled. Place 10S in the above environment for 2 hours. After leaving for 2 hours, the width of sample 10S is measured. Next, the weight for applying a load of 0.2 N is changed to a weight for applying a load of 0.6 N, and the width of the sample 10S is measured 5 minutes after the change. Finally, the weight is changed to a weight for applying a load of 1.0 N, and the width of the sample 10S is measured 5 minutes after the change.

As described above, the load applied in the longitudinal direction of the sample 10S can be changed by adjusting the weight of the weight 233. With each load applied, light L is irradiated from the light emitter 234 toward the receiver 235, and the width of the sample 10S to which the load is applied in the longitudinal direction is measured. The measurement of the width is performed in a state where the sample 10S is not curled. The light emitter 234 and the light receiver 235 are provided in the digital dimension measuring instrument LS-7000.

(Coefficient of thermal expansion α)
The coefficient of thermal expansion α of the magnetic tape MT is preferably 6 [ppm / ° C] ≤ α ≤ 8 [ppm / ° C]. When the coefficient of thermal expansion α is in the above range, the change in the width of the magnetic tape MT can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic tape MT by the recording / reproducing device.

（但し、式中、Ｄ（４５℃）、Ｄ（１０℃）はそれぞれ、温度４５℃、１０℃におけるサンプル１０Ｓの幅を示す。） The coefficient of thermal expansion α is obtained as follows. First, a sample 10S is prepared in the same manner as in the method for measuring the amount of dimensional change Δw, and the sample 10S is set in the same measuring device as in the method for measuring the amount of dimensional change Δw. It is housed in a chamber controlled in a constant environment. Next, a load of 0.2 N is applied in the longitudinal direction of the sample 10S to acclimatize the sample 10S to the above environment. Then, while maintaining a relative humidity of 24%, the temperature is changed in the order of 45 ° C., 29 ° C., 10 ° C., the width of the sample 10S at 45 ° C. and 10 ° C. is measured, and the coefficient of thermal expansion α is obtained from the following formula. .. The width of the sample 10S at a temperature of 29 ° C. is measured in order to confirm whether or not an abnormality has occurred in the measurement (particularly in order to confirm that these three measurement results are linear). The measurement result is not used in the following formula.

(However, in the formula, D (45 ° C.) and D (10 ° C.) indicate the width of the sample 10S at a temperature of 45 ° C. and 10 ° C., respectively.)

(Humidity expansion coefficient β)
The humidity expansion coefficient β of the magnetic tape MT is preferably β ≦ 5 [ppm /% RH]. When the coefficient of thermal expansion β is in the above range, the change in the width of the magnetic tape MT can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic tape MT by the recording / reproducing device.

（但し、式中、Ｄ（８０％）、Ｄ（１０％）はそれぞれ、湿度８０％、１０％におけるサンプル１０Ｓの幅を示す。） The coefficient of thermal expansion β is obtained as follows. First, a sample 10S is prepared in the same manner as in the method for measuring the amount of dimensional change Δw, and the sample 10S is set in the same measuring device as in the method for measuring the amount of dimensional change Δw. It is housed in a chamber controlled in a constant environment. Next, a load of 0.2 N is applied in the longitudinal direction of the sample 10S to acclimatize the sample 10S to the above environment. Then, while maintaining the temperature of 29 ° C., the relative humidity is changed in the order of 80%, 24%, and 10%, the width of the sample 10S at 80% and 10% is measured, and the coefficient of thermal expansion β is obtained from the following formula. .. The width of the sample 10S at a humidity of 24% is measured to confirm that no abnormality has occurred in the measurement (particularly to confirm that these three measurement results are linear). The measurement result is not used in the following formula.

(However, in the formula, D (80%) and D (10%) indicate the width of the sample 10S at a humidity of 80% and 10%, respectively.)

(Poisson's ratio ρ)
The Poisson's ratio ρ of the magnetic tape MT is preferably 0.3 ≦ ρ. When the Poisson's ratio ρ is in the above range, the change in the width of the magnetic tape MT can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic tape MT by the recording / reproducing device.

Poisson's ratio ρ is obtained as follows. First, a 1/2 inch wide magnetic tape MT is prepared, cut out to a length of 150 mm to prepare a sample, and then a mark having a size of 6 mm × 6 mm is given to the central portion of the sample. Next, both ends of the sample in the longitudinal direction are chucked so that the distance between the chucks is 100 mm, an initial load of 2N is applied, and the length of the mark in the longitudinal direction of the sample at that time is set as the initial length, and the width of the sample is set. The width of the mark in the direction is set as the initial width. Then, at a tensile speed of 0.5 mm / min, the sample was pulled by an Instron-type universal tensile tester, and the keyence image sensor was used to measure the length of the mark in the longitudinal direction of the sample and the width of the mark in the width direction of the sample. Measure the amount of each dimensional change. After that, the Poisson's ratio ρ is calculated from the following equation.

(Elastic limit value in the longitudinal direction σ _MD )
The elastic limit value σ _{MD in} the longitudinal direction of the magnetic tape MT is preferably 0.8 [N] ≦ σ _MD . When the elastic limit value σ _MD is in the above range, the change in the width of the magnetic tape MT can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic tape MT by the recording / reproducing device. In addition, it becomes easier to control the drive side. The upper limit of the elastic limit value σ _{MD in} the longitudinal direction of the magnetic tape MT is not particularly limited, but is, for example, σ _MD ≤ 5.0 [N]. It is preferable that the elastic limit value σ _MD does not depend on the tensile speed V when performing the elastic limit measurement. Since the elastic limit value σ _MD does not depend on the tensile speed V, the magnetic tape is effectively magnetic without being affected by the traveling speed of the magnetic tape MT in the recording / playback device, the tension adjustment speed of the recording / playback device, and its responsiveness. This is because the change in the width of the tape MT can be suppressed. The elastic limit value σ _MD is set to a desired value by, for example, selecting the curing conditions of the base layer 42, the recording layer 43 and the back layer 44, and selecting the material of the base 41. For example, the longer the curing time of the base layer forming paint, the recording layer forming paint, and the back layer forming paint, or the higher the curing temperature, the more the reaction between the binder contained in each of these paints and the curing agent accelerates. .. As a result, the elastic characteristics are improved and the elastic limit value σ _MD is improved.

The elastic limit value σ _MD is obtained as follows. First, a 1/2 inch wide magnetic tape MT is prepared, cut out to a length of 150 mm to prepare a sample, and the sample is placed in a universal tensile test device so that the distance between chucks λ ₀ is λ ₀ = 100 mm. Chuck both ends in the longitudinal direction. Next, the sample is pulled at a tensile speed of 0.5 mm / min, and the load σ (N) with respect to the interchuck distance λ (mm) is continuously measured. Subsequently, the obtained data of λ (mm) and σ (N) are used to graph the relationship between Δλ (%) and σ (N). However, Δλ (%) is given by the following equation.
Δλ (%) = ((λ-λ0) / λ0) × 100
Next, in the above graph, a region in which the graph becomes a straight line is calculated in the region of σ ≧ 0.2N, and the maximum load σ thereof is set as the elastic limit value σ _MD (N).

(Interlayer friction coefficient μ)
The inter-story friction coefficient μ between the magnetic surface and the back surface is preferably 0.20 ≦ μ ≦ 0.80. When the inter-story friction coefficient μ is in the above range, it is possible to suppress the occurrence of winding misalignment when the magnetic tape MT is wound on a reel (for example, the reel 13 in FIG. 2). More specifically, when the interlayer friction coefficient μ is μ <0.20, the magnetic surface of the magnetic tape MT already wound on the cartridge reel, which is located on the outermost periphery, and newly wound on the outer side thereof. The interlayer friction between the magnetic tape MT to be wound and the back surface is extremely low, and the magnetic tape MT to be newly wound is located on the outermost periphery of the already wound magnetic tape MT. It becomes easy to shift from the magnetic surface. Therefore, the winding deviation of the magnetic tape MT occurs. On the other hand, when the inter-story friction coefficient μ is 0.80 <μ, the tape is wound around the back surface of the magnetic tape MT that is about to be unwound from the outermost periphery of the drive-side reel and the drive reel that is located directly below the magnetic tape MT. The interlayer friction between the magnetic tape MT and the magnetic surface of the magnetic tape MT as it is left is extremely high, and the back surface and the magnetic surface are stuck to each other. Therefore, the operation of the magnetic tape MT toward the cartridge reel becomes unstable, which causes the magnetic tape MT to be unwound.

The inter-story friction coefficient μ is obtained as follows. First, a 1/2 inch wide magnetic tape MT is wound around a 1 inch diameter cylinder with the back surface facing up, and the magnetic tape MT is fixed. Next, a 1/2 inch wide magnetic tape MT is brought into contact with this cylinder at a holding angle θ (°) = 180 ° + 1 ° to 180 ° -10 ° so that the magnetic surface is in contact with the magnetic tape. One end of the MT is connected to a movable strain gauge, and tension T0 = 0.6 (N) is applied to the other end. When the movable strain gauge is reciprocated 8 times at 0.5 mm / s, the strain gauge readings T1 (N) to T8 (N) are measured on each outward route, and the average value of T4 to T8 is T _ave (N). ). After that, the inter-story friction coefficient μ is calculated from the following formula.

(Surface roughness R _{b of the} back surface)
The surface roughness of the back surface (surface roughness of the back layer 44) R _b is preferably R _b ≤ 6.0 [nm]. When the surface roughness R _b of the back surface is in the above range, the electromagnetic conversion characteristics can be improved.

The surface roughness R _b of the back surface is obtained as follows. First, a 1/2 inch wide magnetic tape MT is prepared and attached to a slide glass with its back surface facing up to prepare a sample piece. Next, the surface roughness of the back surface of the sample piece is measured by a non-contact roughness meter using the following optical interference.
Equipment: Non-contact roughness meter using optical interference (Non-contact surface / layer cross-sectional shape measurement system VertScan R5500GL-M100-AC manufactured by Ryoka System Co., Ltd.)
Objective lens: 20x (approx. 237 μm x 178 μm field of view)
Resolution: 640 points x 480 points
Measurement mode: phase
Wavelength filter: 520 nm
Surface correction: Correction with a quadratic polynomial approximation surface As described above, after measuring the surface roughness at at least 5 points or more in the longitudinal direction, each of them is automatically calculated from the surface profile obtained at each position. Let the average value of the arithmetic average roughness Sa (nm) of the back surface be the surface roughness R _b (nm) of the back surface.

(Coercive force Hc)
The coercive force Hc measured in the thickness direction (vertical direction) of the magnetic tape MT is preferably 220 kA / m or more and 310 kA / m or less, more preferably 230 kA / m or more and 300 kA / m or less, and even more preferably 240 kA / m or more and 290 kA. It is less than / m. When the coercive force Hc is 220 kA / m or more, the coercive force Hc becomes sufficiently large, so that deterioration of the magnetization signal recorded on the adjacent track due to the leakage magnetic field from the recording head can be suppressed. Therefore, a better SNR can be obtained. On the other hand, when the coercive force Hc is 310 kA / m or less, saturation recording by the recording head becomes easy, so that a more excellent SNR can be obtained.

The above coercive force Hc is obtained as follows. First, a measurement sample is cut out from a long magnetic tape MT, and the M- of the entire measurement sample is used in the thickness direction of the measurement sample (thickness direction of the magnetic tape MT) using a vibrating sample magnetometer (VSM). Measure the H-loop. Next, the coating film (base layer 42, recording layer 43, etc.) is wiped off with acetone, ethanol, etc., leaving only the base 41 for background correction, and VSM is used in the thickness direction of the base 41 (magnetic tape). The MH loop of the substrate 41 is measured in the (thickness direction of MT) direction. Then, the MH loop of the substrate 41 is subtracted from the MH loop of the entire measurement sample to obtain the MH loop after background correction. The coercive force Hc is obtained from the obtained MH loop. It is assumed that all the above-mentioned measurements of the MH loop are performed at 25 ° C. Further, it is assumed that "demagnetic field correction" is not performed when measuring the MH loop in the thickness direction (vertical direction) of the magnetic tape MT. Further, the MH loop may be measured by stacking a plurality of samples to be measured according to the sensitivity of the VSM to be used.

(Ratio R of coercive force Hc (50) and coercive force Hc (25))
The ratio R (= (=) of the coercive force Hc (50) measured in the thickness direction (vertical direction) of the magnetic tape MT at 50 ° C. and the coercive force Hc (25) measured in the thickness direction of the magnetic tape MT at 25 ° C. Hc (50) / Hc (25)) × 100) is preferably 95% or more, more preferably 96% or more, even more preferably 97% or more, and particularly preferably 98% or more. When the ratio R is 95% or more, the temperature dependence of the coercive force Hc becomes small, and deterioration of SNR in a high temperature environment can be suppressed.

The coercive force Hc (25) is obtained in the same manner as the method for measuring the coercive force Hc. Further, the coercive force Hc (50) is obtained in the same manner as the method for measuring the coercive force Hc, except that the measurement sample and the MH loop of the substrate 41 are both measured at 50 ° C.

(Square ratio S1 measured in the traveling direction)
The square ratio S1 measured in the traveling direction of the magnetic tape MT 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. .. When the square ratio S1 is 35% or less, the vertical orientation of the magnetic powder becomes sufficiently high, so that a more excellent SNR can be obtained. Therefore, better electromagnetic conversion characteristics can be obtained. In addition, the shape of the servo signal is improved, which makes it easier to control the drive side.

The square ratio S1 is obtained as follows. First, a measurement sample is cut out from the long magnetic tape MT, and the MH loop of the entire measurement sample corresponding to the traveling direction (longitudinal direction) of the magnetic tape MT is measured using VSM. Next, the coating film (base layer 42, recording layer 43, etc.) is wiped off with acetone, ethanol, etc., leaving only the base 41 for background correction, and the traveling direction (magnetic) of the base 41 is used using VSM. The MH loop of the substrate 41 corresponding to the traveling direction of the tape MT) is measured. Then, the MH loop of the substrate 41 is subtracted from the MH loop of the entire measurement sample to obtain the MH loop after background correction. By substituting the saturated magnetization Ms (emu) and residual magnetization Mr (emu) of the obtained MH loop into the following equation, the square ratio S1 (%) is calculated. It is assumed that all the above-mentioned measurements of the MH loop are performed at 25 ° C. Further, the MH loop may be measured by stacking a plurality of samples to be measured according to the sensitivity of the VSM to be used.
Square ratio S1 (%) = (Mr / Ms) x 100

(Square ratio S2 measured in the vertical direction)
The square ratio S2 measured in the vertical direction (thickness direction) of the magnetic tape MT 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. When the square ratio S2 is 65% or more, the vertical orientation of the magnetic powder becomes sufficiently high, so that a more excellent SNR can be obtained. Therefore, better electromagnetic conversion characteristics can be obtained. In addition, the shape of the servo signal is improved, which makes it easier to control the drive side.

The square ratio S2 is obtained in the same manner as the square ratio S1 except that the MH loop is measured in the vertical direction (thickness direction) of the magnetic tape MT and the substrate 41. In the measurement of the square ratio S2, "demagnetic field correction" when measuring the MH loop in the vertical direction of the magnetic tape MT is not performed.

The square ratios S1 and S2 are, for example, the strength of the magnetic field applied to the recording layer forming coating material, the application time of the magnetic field to the recording layer forming coating material, the dispersed state of the magnetic powder in the recording layer forming coating material, or the recording layer forming. A desired value is set by adjusting the concentration of solid content in the paint for use. Specifically, for example, as the strength of the magnetic field is increased, the square ratio S1 becomes smaller, whereas the square ratio S2 becomes larger. Further, as the application time of the magnetic field is lengthened, the square ratio S1 becomes smaller, while the square ratio S2 becomes larger. Further, as the dispersed state of the magnetic powder is improved, the square ratio S1 becomes smaller, while the square ratio S2 becomes larger. Further, as the concentration of the solid content is lowered, the square ratio S1 becomes smaller, while the square ratio S2 becomes larger. The above adjustment method may be used alone or in combination of two or more.

(Hc2 / Hc1)
The ratio of the coercive force Hc1 in the vertical direction to the coercive force Hc2 in the longitudinal direction Hc2 / Hc1 is Hc2 / Hc1 ≦ 0.8, preferably Hc2 / Hc1 ≦ 0.75, more preferably Hc2 / Hc1 ≦ 0.7, Even more preferably, the relationship of Hc2 / Hc1 ≦ 0.65, and particularly preferably Hc2 / Hc1 ≦ 0.6 is satisfied. When the coercive forces Hc1 and Hc2 satisfy the relationship of Hc2 / Hc1 ≦ 0.8, the degree of vertical orientation of the magnetic powder can be increased. Therefore, the magnetization transition width can be reduced and a high-output signal can be obtained during signal reproduction, so that the electromagnetic conversion characteristics (for example, C / N) can be improved. As described above, when Hc2 is small, the magnetization reacts with high sensitivity by the magnetic field in the vertical direction from the recording head, so that a good recording pattern can be formed.

When the ratio Hc2 / Hc1 is Hc2 / Hc1 ≦ 0.8, it is particularly effective that the average thickness of the recording layer 43 is 90 nm or less. When the average thickness of the recording layer 43 exceeds 90 nm, when a ring-shaped head is used as the recording head, the lower region (region on the base layer 42 side) of the recording layer 43 is magnetized in the longitudinal direction, and the recording layer 43 May not be able to be magnetized uniformly in the thickness direction. Therefore, even if the ratio Hc2 / Hc1 is set to Hc2 / Hc1 ≦ 0.8 (that is, even if the vertical orientation of the magnetic powder is increased), the electromagnetic conversion characteristics (for example, C / N) may not be improved. ..

The lower limit of Hc2 / Hc1 is not particularly limited, but is, for example, 0.5 ≦ Hc2 / Hc1. Hc2 / Hc1 represents the vertical orientation of the magnetic powder, and the smaller the Hc2 / Hc1, the higher the vertical orientation of the magnetic powder.

(SFD)
In the SFD (Switching Field Distribution) curve of the magnetic tape MT, the peak ratio X / Y of the main peak height X and the sub-peak height Y near zero magnetic field is preferably 3.0 or more, more preferably 5.0. Above, even more preferably 7.0 or more, particularly preferably 10.0 or more, and most preferably 20.0 or more. When the peak ratio X / Y is 3.0 or more, in addition to the ε-iron oxide particles that contribute to the actual recording, low coercive force components peculiar to ε-iron oxide (for example, soft magnetic particles and superparamagnetic particles) are magnetic powder. It can be suppressed that it is contained in a large amount. Therefore, it is possible to suppress deterioration of the magnetization signal recorded on the adjacent track due to the leakage magnetic field from the recording head, so that a better SNR can be obtained. The upper limit of the peak ratio X / Y is not particularly limited, but is, for example, 100 or less.

The above peak ratio X / Y is obtained as follows. First, the MH loop after background correction is obtained in the same manner as the above-mentioned method for measuring the coercive force Hc. Next, the SFD curve is calculated from the obtained MH loop. A program attached to the measuring machine may be used for calculating the SFD curve, or another program may be used. Let "Y" be the absolute value of the point where the calculated SFD curve crosses the Y axis (dM / dH), and let "X" be the height of the main peak seen near the coercive force Hc in the MH loop. The peak ratio X / Y is calculated. It is assumed that the measurement of the MH loop is performed at 25 ° C. in the same manner as the above-mentioned method for measuring the coercive force Hc. Further, it is assumed that "demagnetic field correction" is not performed when measuring the MH loop in the thickness direction (vertical direction) of the magnetic tape MT. Further, the MH loop may be measured by stacking a plurality of samples to be measured according to the sensitivity of the VSM to be used.

(Activation volume V _act )
Activation volume V _act is preferably 8000 nm ³ or less, more preferably 6000 nm ³ or less, still more preferably 5000 nm ³ or less, particularly preferably 4000 nm ³ or less, most preferably 3000 nm ³ or less. When the activated volume V _act is 8000 nm ³ or less, the dispersed state of the magnetic powder becomes good, so that the bit inversion region can be steep, and the leakage magnetic field from the recording head causes recording on an adjacent track. Deterioration of the magnetization signal can be suppressed. Therefore, there is a risk that a better SNR cannot be obtained.

The above activated volume V _act is calculated by the following formula derived by Street & Woolley.
V _act (nm ³ ) = k _B × T × Χ _irr / (μ ₀ × Ms × S)
(However, k _B : Boltzmann constant (1.38 × 10 ^-23 J / K), T: temperature (K), Χ _irr : irreversible magnetic susceptibility, μ ₀ : vacuum magnetic permeability, S: magnetic viscosity coefficient, Ms: Saturation magnetization (emu / cm ³ ))

The irreversible magnetic susceptibility Χ _irr , the saturation magnetization Ms, and the magnetic viscosity coefficient S substituted in the above equation are obtained by using VSM as follows. The measurement direction by VSM is the thickness direction (vertical direction) of the magnetic tape MT. Further, the measurement by VSM shall be performed at 25 ° C. for the measurement sample cut out from the long magnetic tape MT. Further, it is assumed that "demagnetic field correction" is not performed when measuring the MH loop in the thickness direction (vertical direction) of the magnetic tape MT. Further, the MH loop may be measured by stacking a plurality of samples to be measured according to the sensitivity of the VSM to be used.

(Lossy susceptibility Χ _irr )
The irreversible magnetic susceptibility Χ _irr is defined as the slope near the residual coercive force Hr in the slope of the residual magnetization curve (DCD curve). First, a magnetic field of -1193 kA / m (15 kOe) is applied to the entire magnetic tape MT, and the magnetic field is returned to zero to bring it into a residual magnetization state. Then, a magnetic field of about 15.9 kA / m (200 Oe) is applied in the opposite direction to return it to zero again, and the residual magnetization amount is measured. After that, similarly, the measurement of applying a magnetic field 15.9 kA / m larger than the applied magnetic field to return it to zero is repeated, and the residual magnetization amount is plotted against the applied magnetic field to measure the DCD curve. From the obtained DCD curve, the point where the amount of magnetization becomes zero is defined as the residual coercive force Hr, and the DCD curve is further differentiated to obtain the slope of the DCD curve in each magnetic field. In the slope of this DCD curve, the slope near the residual coercive force Hr is Χ _irr .

(Saturation magnetization Ms)
First, the MH loop of the entire magnetic tape MT (measurement sample) is measured in the thickness direction of the magnetic tape MT. Next, the coating film (base layer 42, recording layer 43, etc.) is wiped off with acetone, ethanol, or the like, leaving only the base 41, and the MH loop of the base 41 is similarly thickened for background correction. Measure in the direction. Then, the MH loop of the substrate 41 is subtracted from the MH loop of the entire magnetic tape MT to obtain the MH loop after background correction. Ms (emu / cm ³ ) is calculated from the value of the saturation magnetization Ms (emu) of the obtained MH loop and the volume (cm ³ ) of the recording layer 43 in the measurement sample. The volume of the recording layer 43 is obtained by multiplying the area of the measurement sample by the average thickness of the recording layer 43. Further, the MH loop may be measured by stacking a plurality of samples to be measured according to the sensitivity of the VSM to be used. The method of calculating the average thickness of the recording layer 43 required for calculating the volume of the recording layer 43 will be described later.

(Magnetic viscosity coefficient S)
First, a magnetic field of -1193 kA / m (15 kOe) is applied to the entire magnetic tape MT (measurement sample), and the magnetic field is returned to zero to be in a residual magnetization state. Then, in the opposite direction, a magnetic field equivalent to the value of the residual coercive force Hr obtained from the DCD curve is applied. The amount of magnetization is continuously measured at regular time intervals for 1000 seconds while a magnetic field is applied. The magnetic viscosity coefficient S is calculated by comparing the relationship between the time t and the amount of magnetization M (t) thus obtained with the following equation.
M (t) = M0 + S × ln (t)
(However, M (t): magnetization amount at time t, M0: initial magnetization amount, S: magnetic viscosity coefficient, ln (t): natural logarithm of time)

(BET specific surface area)
The lower limit of the total BET specific surface area of the magnetic tape MT in the state where the lubricant is removed is 3.5 m ² / mg or more, preferably 4 m ² / mg or more, more preferably 4.5 m ² / mg or more, and even more. It is preferably 5 m ² / mg or more. When the lower limit of the BET specific surface area is 3.5 m ² / mg or more, even after repeated recording or reproduction (that is, even after the magnetic head is brought into contact with the surface of the magnetic tape MT and repeated running). It is possible to suppress a decrease in the amount of lubricant supplied between the surface of the recording layer 43 and the magnetic head. Therefore, it is possible to suppress an increase in the dynamic friction coefficient.

The upper limit of the total BET specific surface area of the magnetic tape MT in the state where the lubricant is removed is preferably 7 m ² / mg or less, more preferably 6 m ² / mg or less, and even more preferably 5.5 m ² / mg or less. is there. When the upper limit of the BET specific surface area is 7 m ² / mg or less, the lubricant can be sufficiently supplied without being exhausted even after a large number of runs. Therefore, it is possible to suppress an increase in the dynamic friction coefficient.

The average pore diameter of the entire magnetic tape MT determined by the BJH method is 6 nm or more and 11 nm or less, preferably 7 nm or more and 10 nm or less, and more preferably 7.5 nm or more and 10 nm or less. When the average pore diameter is 6 nm or more and 11 nm or less, the effect of suppressing the increase in the dynamic friction coefficient described above can be further improved.

The BET specific surface area and pore distribution (pore volume, pore diameter of maximum pore volume at the time of desorption) can be obtained as follows. First, the magnetic tape MT is washed with hexane for 24 hours, and then cut into a size of 0.1265 m ² to prepare a measurement sample. Next, the BET specific surface area is determined using a specific surface area / pore distribution measuring device. Further, the pore distribution (pore volume, pore diameter of the maximum pore volume at the time of desorption) is determined by the BJH method. The measuring device and measuring conditions are shown below.
Measuring device: Micromeritics 3FLEX
Measurement adsorbent: N ₂ gas Measurement pressure range (p / p0): 0 to 0.995

(Arithmetic Mean Roughness Ra)
The arithmetic mean roughness Ra of the magnetic surface is preferably 2.5 nm or less, more preferably 2.0 nm or less. When Ra is 2.5 nm or less, a better SNR can be obtained.

The above arithmetic mean roughness Ra is obtained as follows. First, an AFM (Atomic Force Microscope) (manufactured by Bruker, Dimension Icon) is used to observe the surface on the side where the recording layer 43 is provided to acquire a cross-sectional profile. Next, the arithmetic mean roughness Ra is obtained from the acquired cross-sectional profile in accordance with JIS B0601: 2001.

[Manufacturing method of magnetic tape]
Next, an example of a method for manufacturing a magnetic tape MT having the above configuration will be described. First, a coating material for forming an underlayer is prepared by kneading and dispersing a non-magnetic powder, a binder and the like in a solvent. Next, a coating material for forming a recording layer is prepared by kneading and dispersing a magnetic powder, a binder and the like in a solvent. For the preparation of the coating material for forming the recording layer and the coating material for forming the base layer, for example, the following solvent, dispersion device and kneading device can be used.

Examples of the solvent used for preparing the above-mentioned paint include a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, an alcohol solvent such as methanol, ethanol and propanol, methyl acetate, ethyl acetate, butyl acetate and propyl acetate. , Ester solvents such as ethyl lactate and ethylene glycol acetate, ether solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran and dioxane, aromatic hydrocarbon solvents such as benzene, toluene and xylene, methylene chloride, ethylene chloride, Examples thereof include halogenated hydrocarbon solvents such as carbon tetrachloride, chloroform and chlorobenzene. These may be used alone or may be mixed appropriately.

As the kneading device used for the above-mentioned paint preparation, for example, a continuous twin-screw kneader, a continuous twin-screw kneader that can be diluted in multiple stages, a kneader, a pressure kneader, a roll kneader, or the like can be used. However, the device is not particularly limited to these devices. Further, as the disperser used for the above-mentioned paint preparation, for example, a roll mill, a ball mill, a horizontal sand mill, a vertical sand mill, a spike mill, a pin mill, a tower mill, a pearl mill (for example, "DCP mill" manufactured by Erich, etc.), a homogenizer, and an ultra Dispersing devices such as a sound wave disperser can be used, but the device is not particularly limited to these devices.

Next, the base layer 42 is formed by applying the base layer forming paint to one main surface of the base 41 and drying it. Subsequently, the recording layer 43 is formed on the base layer 42 by applying the recording layer forming paint on the base layer 42 and drying it. At the time of drying, the magnetic powder is magnetically oriented in the thickness direction of the substrate 41 by, for example, a solenoid coil. Further, at the time of drying, the magnetic powder may be magnetically oriented in the traveling direction (longitudinal direction) of the substrate 41 by, for example, a solenoid coil, and then magnetically oriented in the thickness direction of the substrate 41. After the recording layer 43 is formed, the back layer 44 is formed on the other main surface of the substrate 41. As a result, the magnetic tape MT is obtained.

Then, the obtained magnetic tape MT is rewound on a large-diameter core and cured. Finally, the magnetic tape MT is subjected to calendar processing and then cut into a predetermined width (for example, 1/2 inch width). From the above, the desired elongated magnetic tape MT can be obtained.

[Configuration of recording / playback device]
The recording / reproducing device 50 records and reproduces the magnetic tape MT having the above-described configuration. The recording / reproducing device 50 has a configuration in which the tension applied in the longitudinal direction of the magnetic tape MT can be adjusted. Further, the recording / reproducing device 50 has a configuration in which the cartridge 10 can be loaded. Here, for the sake of simplicity, a case where the recording / playback device 50 has a configuration in which one cartridge 10 can be loaded will be described, but the recording / playback device 50 can load a plurality of cartridges 10. It may have various configurations.

The recording / playback device 50 is connected to information processing devices such as a server 71 and a personal computer (hereinafter referred to as “PC”) 72 via a network 70, and data supplied from these information processing devices is sent to the cartridge 10. It is configured to be recordable. Further, in response to a request from these information processing devices, data can be reproduced from the cartridge 10 and supplied to these information processing devices. The shortest recording wavelength of the recording / reproducing device 50 is preferably 100 nm or less, more preferably 75 nm or less, still more preferably 60 nm or less, and particularly preferably 50 nm or less.

As shown in FIG. 1, the recording / playback device 50 includes a spindle 51, a reel 52 on the recording / playback device 50 side, a spindle drive device 53, a reel drive device 54, a plurality of guide rollers 55, and a head unit 56. A reader / writer 57 as a communication unit, a communication interface (hereinafter, I / F) 58, and a control device 59 are provided.

The spindle 51 is configured so that the cartridge 10 can be mounted. A V-shaped servo pattern is pre-recorded on the magnetic tape MT as a servo signal. The reel 52 is configured to be able to fix the tip (leader pin 22) of the magnetic tape MT pulled out from the cartridge 10 via a tape loading mechanism (not shown).

The spindle drive device 53 rotates the spindle 51 in response to a command from the control device 59. The reel drive device 54 rotates the reel 52 in response to a command from the control device 59. The plurality of guide rollers 55 guide the traveling of the magnetic tape MT so that the tape paths formed between the cartridge 10 and the reel 52 have a predetermined relative positional relationship with respect to the head unit 56.

When data is recorded on the magnetic tape MT or when data is regenerated from the magnetic tape MT, the spindle drive 53 and the reel drive 54 rotationally drive the spindle 51 and the reel 52. The magnetic tape MT runs. The traveling direction of the magnetic tape MT is such that it can reciprocate in a forward direction (flowing direction from the cartridge 10 side to the reel 52 side) and a reverse direction (flowing direction from the reel 52 side to the cartridge 10 side).

In the present embodiment, the tension in the longitudinal direction of the magnetic tape MT at the time of data recording or data reproduction can be adjusted by controlling the rotation of the spindle 51 by the spindle driving device 53 and controlling the rotation of the reel 52 by the reel driving device 54. It is said that. The tension of the magnetic tape MT may be adjusted by controlling the rotation of the spindle 51 and the reel 52, or by controlling the movement of the guide roller 55 in addition to this control.

The reader / writer 57 is configured to be able to write the first information and the second information to the cartridge memory 11 in response to a command from the control device 59. Further, the reader / writer 57 is configured to be able to read the first information and the second information from the cartridge memory 11 in response to a command from the control device 59. As a communication method between the reader / writer 57 and the cartridge memory 11, for example, the ISO14443 method is adopted. The second information includes tension adjustment information. The tension adjustment information is an example of information at the time of data recording.

The control device 59 includes, for example, a control unit, a storage unit, a communication unit, and the like. The control unit is composed of, for example, a CPU (Central Processing Unit) or the like, and controls each unit of the recording / playback device 50 according to a program stored in the storage unit. For example, the control device 59 records the data signal supplied from the information processing device on the magnetic tape MT by the head unit 56 in response to the request of the information processing device such as the server 71 and the PC 72. Further, the control device 59 reproduces the data signal recorded on the magnetic tape MT by the head unit 56 and supplies the data signal to the information processing device in response to the request of the information processing device such as the server 71 and the PC 72.

The storage unit includes a non-volatile memory in which various data and various programs are recorded, and a volatile memory used as a work area of the control unit. The various programs may be read from a portable recording medium such as an optical disk or a portable storage device such as a semiconductor memory, or may be downloaded from a server device on a network.

The control device 59 reads the servo signals recorded in the two adjacent servo bands SB by the head unit 56 when the data is recorded on the magnetic tape MT or when the data is reproduced from the magnetic tape MT. The control device 59 uses the servo signals read from the two servo bands SB to control the position of the head unit 56 so that the head unit 56 follows the servo pattern.

The control device 59 determines the distance between the two adjacent servo bands SB (the width direction of the magnetic tape MT) from the reproduced waveform of the servo signal read from the two adjacent servo bands SB when recording the data on the magnetic tape MT. Distance) d1 is obtained. Then, the obtained distance is written to the memory 36 by the reader / writer 57.

When the control device 59 reproduces the data from the magnetic tape MT, the distance between the two adjacent servo band SBs (width of the magnetic tape MT) from the reproduction waveform of the servo signal read from the two adjacent servo bands SB. Distance in direction) d2 is obtained. At the same time, the control device 59 reads the distance d1 between the two adjacent servo bands SB obtained at the time of recording the data on the magnetic tape MT from the memory 36 by the reader / writer 57. In the control device 59, the difference Δd between the distance d1 between the servo bands SB obtained when recording the data on the magnetic tape MT and the distance d2 between the servo bands SB obtained when reproducing the data from the magnetic tape MT is within a specified range. The rotation of the spindle drive device 53 and the reel drive device 54 is controlled so as to be inside, and the tension applied in the longitudinal direction of the magnetic tape MT is adjusted. The control of this tension adjustment is performed by, for example, feedback control.

The head unit 56 is configured to be able to record data on the magnetic tape MT in response to a command from the control device 59. Further, the head unit 56 is configured to be able to reproduce the data recorded on the magnetic tape MT in response to a command from the control device 59. The head unit 56 has, for example, two servo lead heads, a plurality of data write / lead heads, and the like.

The servo lead head is configured to be able to reproduce the servo signal by reading the magnetic field generated from the servo signal recorded on the magnetic tape MT by an MR element (MR: Magneto Resistive) or the like. The distance between the two servo lead heads in the width direction is substantially the same as the distance between the two adjacent servo bands SB.

The data write / lead heads are arranged at positions sandwiched between the two servo lead heads at equal intervals along the direction from one servo lead head to the other servo lead head. The data write / read head is configured to be able to record data on the magnetic tape MT by the magnetic field generated from the magnetic gap. Further, the data write / read head is configured to be able to reproduce the data by reading the magnetic field generated from the data recorded on the magnetic tape MT with an MR element or the like.

The communication I / F 58 is for communicating with information processing devices such as the server 71 and the PC 72, and is connected to the network 70.

[Operation of recording / playback device during data recording]
Hereinafter, an example of the operation of the recording / reproducing device 50 at the time of data recording will be described with reference to FIG. 7.

First, the control device 59 loads the cartridge 10 into the recording / playback device 50 (step S11). Next, the control device 59 controls the rotation of the spindle 51 and the reel 52, and causes the magnetic tape MT to travel while applying a predetermined tension in the longitudinal direction of the magnetic tape MT. Then, the control device 59 reads the servo signal by the servo lead head of the head unit 56, and records the data on the magnetic tape MT by the data write / lead head of the head unit 56 (step S12).

At this time, the head unit 56 records data in the data band DB by the data write / lead head of the head unit 56 while tracing the two adjacent servo band SBs by the two servo lead heads of the head unit 56. To do.

Next, the control device 59 obtains the distance d1 between two adjacent servo bands SB at the time of data recording from the reproduced waveform of the servo signal read by the servo lead head of the head unit 56 (step S13). Next, the control device 59 writes the distance d1 between the servo bands SB at the time of data recording to the cartridge memory 11 by the reader / writer 57 (step S14). The control device 59 may continuously measure the distance d1 between the servo bands SB and write it to the cartridge memory 11, or may measure the distance d1 between the servo bands SB at regular intervals and write it to the cartridge memory 11. When the distance d1 between the servo band SBs is measured at regular intervals and written to the cartridge memory 11, the amount of information written to the memory 36 can be reduced.

[Operation of recording / playback device during data playback]
Hereinafter, an example of the operation of the recording / reproducing device 50 at the time of data reproduction will be described with reference to FIG.

First, the control device 59 loads the cartridge 10 into the recording / playback device 50 (step S21). Next, the control device 59 reads out the distance d1 between the servo bands SB at the time of recording from the cartridge memory 11 by the reader / writer 57 (step S22).

Next, the control device 59 controls the rotation of the spindle 51 and the reel 52, and causes the magnetic tape MT to travel while applying a predetermined tension in the longitudinal direction of the magnetic tape MT. Then, the control device 59 reads the servo signal by the servo lead head of the head unit 56, and reproduces the data from the magnetic tape MT by the data write / lead head of the head unit 56 (step S23).

Next, the control device 59 calculates the distance d2 between two adjacent servo bands SB at the time of data reproduction from the reproduction waveform of the servo signal read by the servo lead head of the head unit 56 (step S24). ..

Next, the control device 59 determines whether or not the difference Δd between the distance d1 between the servo bands SB read in step S22 and the distance d2 between the servo bands SB calculated in step S24 is within the specified value. (Step S25).

When it is determined in step S25 that the difference Δd is within the specified value, the control device 59 controls the rotation of the spindle 51 and the reel 52 so that the specified tension is maintained (step S26).

On the other hand, when it is determined in step S25 that the difference Δd is not within the specified value, the control device 59 controls the rotation of the spindle 51 and the reel 52 so that the difference Δd becomes small, and travels the magnetic tape MT. The tension applied to the device is adjusted, and the process returns to step S24 (step S27).

[effect]
As described above, in the first embodiment, the average thickness t _T of the magnetic tape MT is t _T ≤ 5.5 [μm], and the magnetic tape MT with respect to the tension change in the longitudinal direction of the magnetic tape MT. The amount of dimensional change Δw in the width direction is 650 [ppm / N] ≦ Δw. Further, the memory (storage unit) 36 of the cartridge memory 11 has an area (second storage area 36B) for writing width-related information related to the width of the magnetic tape MT at the time of data recording. As a result, even if the width of the magnetic tape MT fluctuates for some reason (for example, a change in temperature and humidity), the width-related information is used at the time of data reproduction, and the recording / reproduction device 50 uses the recording / reproduction device 50 in the longitudinal direction of the magnetic tape MT. By adjusting the tension, it is possible to suppress a change in the width of the magnetic tape MT. Therefore, even if the width of the magnetic tape MT fluctuates for some reason, it is possible to suppress a decrease in reproduction reliability.

<2 Second embodiment>
[Configuration of recording / playback device]
FIG. 9 is a schematic view showing an example of the configuration of the recording / reproducing system 100A according to the second embodiment of the present disclosure. The recording / playback system 100A includes a cartridge 10 and a recording / playback device 50A.

The recording / reproducing device 50 further includes a thermometer 60 and a hygrometer 61. The thermometer 60 measures the temperature around the magnetic tape MT (cartridge 10) and outputs the temperature to the control device 59. Further, the hygrometer 40 measures the humidity around the magnetic tape MT (cartridge 10) and outputs the humidity to the control device 59.

The control device 59 measures the temperature Tm1 and the humidity H1 around the magnetic tape MT (cartridge 10) by the thermometer 39 and the hygrometer 40 at the time of recording the data on the magnetic tape MT, and the cartridge memory via the reader / writer 57. Write in 11. The temperature Tm1 and the humidity H1 are examples of environmental information around the magnetic tape MT.

The control device 59 obtains the tension Tn1 applied in the longitudinal direction of the magnetic tape MT based on the drive data of the spindle 51 and the reel 52 when recording the data on the magnetic tape MT, and obtains the tension Tn1 applied in the longitudinal direction of the magnetic tape MT, and obtains the tension Tn1 applied in the longitudinal direction of the magnetic tape MT. Write to.

The control device 59 obtains the distance d1 between the two adjacent servo bands SB from the reproduced waveform of the servo signal read from the two adjacent servo bands SB when recording the data on the magnetic tape MT. Then, based on this distance d1, the width W1 of the magnetic tape MT at the time of data recording is calculated and written to the memory 36 by the reader / writer 57.

The control device 59 measures the temperature Tm2 and the humidity H2 around the magnetic tape MT (cartridge 10) by the thermometer 39 and the hygrometer 40 when reproducing the data from the magnetic tape MT.

The control device 59 obtains the tension Tn2 applied in the longitudinal direction of the magnetic tape MT based on the drive data of the spindle 51 and the reel 52 when reproducing the data from the magnetic tape MT.

The control device 59 obtains the distance d2 between the two adjacent servo bands SB from the reproduced waveform of the servo signal read from the two adjacent servo bands SB when the data from the magnetic tape MT is reproduced. Then, based on this distance d2, the width W2 of the magnetic tape MT at the time of data reproduction is calculated.

When the data from the magnetic tape MT is reproduced, the control device 59 reads the temperature Tm1, the humidity H1, the tension Tn1 and the width W1 written at the time of data recording from the cartridge memory 11 via the reader / writer 57. Then, the control device 59 uses the temperature Tm1, humidity H1, tension Tn1 and width W1 at the time of data recording, and the temperature Tm2, humidity H2, tension Tn2 and width W2 at the time of data reproduction, and magnetically at the time of data reproduction. The tension applied to the magnetic tape MT is controlled so that the width W2 of the tape MT is equal to or substantially equal to the width W1 of the magnetic tape at the time of data recording.

The controller 35 of the cartridge memory 11 stores the temperature Tm1, the humidity H1, the tension Tn1 and the width W1 received from the recording / reproducing device 50A via the antenna coil 31 in the second storage area 36B of the memory 36. The controller 35 of the cartridge memory 11 reads the temperature Tm1, the humidity H1, the tension Tn1 and the width W1 from the memory 36 in response to the request from the recording / reproducing device 50A, and transmits them to the recording / reproducing device 50A via the antenna coil 31.

[Operation of recording / playback device during data recording]
Hereinafter, an example of the operation of the recording / reproducing device 50A at the time of data recording will be described with reference to FIG.

First, the control device 59 loads the cartridge 10 into the recording / playback device 50 (step S101). Next, the control device 59 controls the rotation of the spindle 51 and the reel 52, and causes the magnetic tape MT to travel while applying a predetermined tension in the longitudinal direction of the magnetic tape MT. Then, the control device 59 records data on the magnetic tape MT by the head unit 56 (step S102).

Next, the control device 59 acquires the temperature Tm1 and the humidity H1 (environmental information) around the magnetic tape MT at the time of data recording from the thermometer 39 and the hygrometer 40 (step S103).

Next, the control device 59 calculates the tension Tn1 applied in the longitudinal direction of the magnetic tape MT at the time of data recording based on the drive data of the spindle 51 and the reel 52 at the time of data recording (step S104).

Next, the control device 59 obtains the distance d1 between the two adjacent servo bands SB from the reproduced waveform of the servo signal read by the servo lead head of the head unit 56. Next, the control device 59 calculates the width W1 of the magnetic tape MT at the time of data recording based on this distance d1 (step S105).

Next, the control device 59 writes the temperature Tm1, the humidity H1, the tension Tn1 and the width W1 of the magnetic tape MT into the cartridge memory 11 as data recording information by the reader / writer 57 (step S106).

[Operation of recording / playback device during data playback]
Hereinafter, an example of the operation of the recording / reproducing device 50A at the time of data reproduction will be described with reference to FIG.

First, the control device 59 loads the cartridge 10 into the recording / playback device 50 (step S111). Next, the control device 59 reads the data recording information (temperature Tm1, humidity H1, tension Tn1 and width W1 of the magnetic tape MT) written in the cartridge memory 11 from the cartridge memory 11 by the reader / writer 57, and acquires the information. (Step S112). Next, the control device 59 acquires information on the temperature Tm2 and humidity H2 around the current magnetic tape MT at the time of data reproduction by the thermometer 39 and the hygrometer 40 (step S113).

Next, the control device 59 calculates the temperature difference TmD (TmD = Tm2-Tm1) between the temperature Tm1 at the time of data recording and the temperature Tm2 at the time of data reproduction (step S114). Further, the control device 59 calculates the humidity difference HD (HD = H2-H1) between the humidity H1 at the time of data recording and the humidity H2 at the time of data reproduction (step S115).

Next, the control device 59 multiplies the temperature difference TmD by the coefficient α (TmD × α) and multiplies the humidity difference HD by the coefficient β (HD × β) (step S116). The coefficient α is a value indicating how much the tension of the magnetic tape MT should be changed as compared with the tension Tn1 at the time of data recording per 1 ° C. of the temperature difference. The coefficient β is a value indicating how much the tension of the magnetic tape MT should be changed with respect to the tension Tn1 at the time of data recording per 1% humidity difference.

Next, the control device 59 adds the value of TmD × α and the value of HD × β to the tension Tn1 at the time of data recording, so that the length of the magnetic tape MT at the time of data reproduction (current) The tension Tn2 to be applied in the direction is calculated (step S117).
Tn2 = Tn1 + TmD x α + HD x β

After determining the tension Tn2 of the magnetic tape MT at the time of data reproduction, the control device 59 controls the rotation of the spindle 51 and the reel 52, and controls the traveling of the magnetic tape MT so that the magnetic tape MT travels with the tension Tn2. To do. Then, the control device 59 reproduces the data recorded in the data track Tk by the data write / lead head of the head unit 56 while reading the servo signal of the servo band SB by the servo lead head of the head unit 56.

At this time, since the width of the magnetic tape MT is adjusted to the width at the time of data recording by adjusting the tension of the magnetic tape MT, the data write / read head of the head unit 56 is accurately positioned with respect to the data track Tk. Can be matched. As a result, even if the width of the magnetic tape MT fluctuates for some reason (for example, fluctuations in temperature and humidity), the data recorded on the magnetic tape MT can be accurately reproduced.

At the time of data reproduction (current), the value of the tension Tn2 to be applied to the magnetic tape MT becomes higher if the temperature at the time of data reproduction is higher than the temperature at the time of data recording. Therefore, when the temperature rises and the width of the magnetic tape MT becomes wider than that at the time of data recording, the width of the magnetic tape MT can be narrowed to reproduce the same width as at the time of data reproduction.

On the contrary, at the time of data reproduction (current), the value of tension Tn2 to be applied to the magnetic tape MT becomes lower if the temperature at the time of data reproduction is lower than the temperature at the time of data recording. Therefore, when the temperature becomes low and the width of the magnetic tape MT becomes narrower than that at the time of data recording, the width of the magnetic tape MT can be widened to reproduce the same width as at the time of data reproduction.

Further, at the time of data reproduction (current), the value of the tension Tn2 to be applied to the magnetic tape MT becomes higher if the humidity at the time of data reproduction is higher than the humidity at the time of data recording. Therefore, when the humidity becomes high and the width of the magnetic tape MT becomes wider than that at the time of data recording, the width of the magnetic tape MT can be narrowed to reproduce the same width as at the time of data reproduction.

On the contrary, at the time of data reproduction (current), the value of the tension Tn2 to be applied to the magnetic tape MT becomes lower if the humidity at the time of data reproduction is lower than the humidity at the time of data recording. Therefore, when the humidity becomes low and the width of the magnetic tape MT becomes narrower than that at the time of data recording, the width of the magnetic tape MT can be widened to reproduce the same width as at the time of data reproduction.

Here, in order to obtain the tension Tn2 to be applied to the magnetic tape MT at the time of data reproduction, in addition to the temperature Tm1 at the time of data recording, the humidity H1, and the tension Tn1 of the magnetic tape MT (or instead of the tension Tn1), Further, the information of the width W1 of the magnetic tape MT at the time of data recording may be used.

In this case as well, the control device 59 similarly calculates the temperature difference TmD (TmD = Tm2-Tm1) and the humidity difference HD (HD = H2-H1). Then, the control device 59 multiplies the temperature difference TmD by the coefficient γ (TmD × γ) and multiplies the humidity difference HD by the coefficient δ (HD × δ) (step S118).

Here, the coefficient γ is a value indicating how much the width of the magnetic tape MT fluctuates per 1 ° C. of a temperature difference (a value indicating an expansion rate per unit length (width direction) based on temperature). The coefficient δ is a value indicating how much the width of the magnetic tape MT fluctuates per 1% of the humidity difference (a value indicating the expansion coefficient per unit length (width direction) based on the humidity).

Next, the control device 59 predicts the width W2 of the current magnetic tape MT at the time of data reproduction based on the width W1 of the past magnetic tape MT at the time of data recording by the following equation.
W2 = W1 (1 + TmD x γ + HD2 x δ)

Next, the control device 59 calculates the difference WD between the width W2 of the current magnetic tape MT at the time of data reproduction and the width W1 of the past magnetic tape MT at the time of data recording (WD = W2-W1 = W1 (WD = W2-W1 = W1). TmD x γ + HD2 x δ)).

Then, the control device 59 adds the value obtained by multiplying the width difference WD by the coefficient ε to the tension Tn1 of the magnetic tape MT at the time of data recording, and calculates the tension Tn2 of the magnetic tape MT at the time of data reproduction Tn2 = Tn1 + WD × ε

Here, the coefficient ε is a value representing the tension in the longitudinal direction of the magnetic tape MT required to change the width of the magnetic tape MT by a unit distance.

After determining the tension Tn2 of the magnetic tape MT at the time of data reproduction, the control device 59 controls the rotation of the spindle 51 and the reel 52, and controls the traveling of the magnetic tape MT so that the magnetic tape MT travels with the tension Tn2. To do. Then, the control device 59 reproduces the data recorded in the data track Tk by the data write / lead head of the head unit 56 while reading the servo signal of the servo band SB by the servo lead head of the head unit 56.

Even when the tension Tn2 is determined by such a method, if the width of the magnetic tape MT fluctuates due to some cause (for example, fluctuations in temperature and humidity), the data recorded on the magnetic tape MT can be used. It can be played accurately.

[effect]
As described above, in the second embodiment, the data recording information of the magnetic tape MT is stored in the cartridge memory 11, and the width of the magnetic tape MT can be appropriately adjusted by using this information at the time of data reproduction. Can be adjusted to. Therefore, even if the width of the magnetic tape MT fluctuates for some reason, the data recorded on the magnetic tape MT can be accurately reproduced.

Further, in the present embodiment, the temperature Tm1 and the humidity H1 (environmental information) around the magnetic tape MT at the time of data recording are written as the data recording information. Therefore, it is possible to appropriately cope with the fluctuation of the width of the magnetic tape MT and the width of the data track Tk due to the fluctuation of temperature and humidity.

<3 Modification example>
(Modification example 1)
In the above-described embodiment, the case where the ε-iron oxide particles have a shell portion having a two-layer structure has been described, but the ε-iron oxide particles may have a shell portion having a single-layer structure. In this case, the shell portion has the same configuration as the first shell portion. However, from the viewpoint of suppressing deterioration of the characteristics of the ε-iron oxide particles, it is preferable that the ε-iron oxide particles have a shell portion having a two-layer structure as in the above-described embodiment.

(Modification 2)
In the above-described embodiment, the case where the ε-iron oxide particles have a core-shell structure has been described, but the ε-iron oxide particles may contain an additive instead of the core-shell structure, and also have a core-shell structure. It may contain additives. In this case, a part of Fe of the ε iron oxide particles is replaced with an additive. Even when the ε-iron oxide particles contain an additive, the coercive force Hc of the entire ε-iron oxide particles can be adjusted to a coercive force Hc suitable for recording, so that the ease of recording can be improved. The additive is a metal element other than iron, preferably a trivalent metal element, more preferably at least one of Al, Ga and In, and even more preferably at least one of Al and Ga.

Specifically, the ε-iron oxide containing the additive is an ε-Fe _2-x M _x O ₃ crystal (where M is a metal element other than iron, preferably a trivalent metal element, more preferably Al, Ga. And at least one of In, and even more preferably at least one of Al and Ga. X is, for example, 0 <x <1).

(Modification 3)
In the above-described embodiment, the case where the magnetic powder contains the powder of ε-iron oxide particles has been described, but the magnetic powder is a nanoparticle containing hexagonal ferrite instead of the powder of ε-iron oxide particles (hereinafter, “hexagonal crystal”). It may contain powder of "ferrite particles"). The hexagonal ferrite particles have, for example, a hexagonal plate shape or a substantially hexagonal plate shape. The hexagonal ferrite preferably contains at least one of Ba, Sr, Pb and Ca, and more preferably at least one of Ba and Sr. Specifically, the hexagonal ferrite may be, 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.

More specifically, hexagonal ferrite has an average composition represented by the general formula MFe ₁₂ O ₁₉ . However, M is, for example, at least one metal among Ba, Sr, Pb and Ca, preferably at least one metal among 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. Further, M may be a combination of Sr and one or more metals selected from the group consisting of Ba, Pb and Ca. In the above general formula, a part of Fe may be replaced with another metal element.

When the magnetic powder contains hexagonal ferrite particle powder, the average particle size of the magnetic powder is preferably 30 nm or less, more preferably 12 nm or more and 25 nm or less, and even more preferably 15 nm or more and 22 nm or less. When the average particle size of the magnetic powder is 30 nm or less, good electromagnetic conversion characteristics (for example, C / N) can be obtained in a magnetic tape MT having a high recording density. On the other hand, when the average particle size of the magnetic powder is 12 nm or more, the dispersibility of the magnetic powder is further improved, and more excellent electromagnetic conversion characteristics (for example, C / N) can be obtained. When the magnetic powder contains a powder of hexagonal ferrite particles, the average aspect ratio of the magnetic powder is the same as that of the above-described embodiment.

The average particle size and average aspect ratio of the magnetic powder are obtained as follows. First, the magnetic tape MT to be measured is processed by the FIB method or the like to prepare flakes, and the cross section of the flakes is observed by TEM. Next, 50 magnetic powders oriented at an angle of 75 degrees or more with respect to the horizontal direction are randomly selected from the TEM photographs taken, and the maximum plate thickness DA of each magnetic powder is measured. Subsequently, the maximum plate thickness DA of the 50 measured magnetic powders is simply averaged (arithmetic mean) to obtain the average maximum plate thickness DAave.

Next, the surface of the recording layer 43 of the magnetic tape MT is observed by TEM. Next, 50 magnetic powders are randomly selected from the TEM photographs taken, and the maximum plate diameter DB of each magnetic powder is measured. Here, the maximum plate diameter DB means the maximum distance (so-called maximum ferret diameter) between two parallel lines drawn from all angles so as to be in contact with the contour of the magnetic powder. Subsequently, the maximum plate diameter DB of the 50 measured magnetic powders is simply averaged (arithmetic mean) to obtain the average maximum plate diameter DBave. The average maximum plate diameter DBave thus obtained is defined as the average particle size of the magnetic powder. Next, the average aspect ratio (DBave / DAave) of the magnetic powder is obtained from the average maximum plate thickness DAave and the average maximum plate diameter DBave.

If the magnetic powder contains a powder of hexagonal ferrite particles, average particle volume of the magnetic powder is preferably 5900Nm ³ or less, more preferably 500 nm ³ or more 3400 nm ³ or less, still more preferably 1000 nm ³ or more 2500 nm ³ or less. When the average particle volume of the magnetic powder is 5900 nm ³ or less, the same effect as when the average particle size of the magnetic powder is 30 nm or less can be obtained. On the other hand, when the average particle volume of the magnetic powder is 500 nm ³ or more, the same effect as when the average particle size of the magnetic powder is 12 nm or more can be obtained.

The average particle volume of the magnetic powder is obtained as follows. First, the average maximum plate thickness DAave and the average maximum plate diameter DBave are obtained in the same manner as in the above method for calculating the average particle size of the magnetic powder. Next, the average particle volume V of the magnetic powder is obtained by the following formula.
V = 3√3 / 8 x DAave x DBave ²

(Modification example 4)
In the above-described embodiment, the case where the magnetic powder contains the powder of ε-iron oxide particles has been described, but the magnetic powder is a nanoparticle containing Co-containing spinel ferrite instead of the powder of ε-iron oxide particles (hereinafter, “cobalt”). It may contain powder of "ferrite particles"). The cobalt ferrite particles preferably have uniaxial anisotropy. The cobalt ferrite particles have, for example, a cubic shape or a substantially 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 (1).
_{Co x M y Fe 2 O Z} ··· (1)
(However, in the formula (1), M is, for example, at least one metal of Ni, Mn, Al, Cu and Zn. X is within the range of 0.4 ≦ x ≦ 1.0. The value y is a value within the range of 0 ≦ y ≦ 0.3. However, x and y satisfy the relationship of (x + y) ≦ 1.0. Z is within the range of 3 ≦ z ≦ 4. It is a value of. A part of Fe may be replaced with another metal element.)

When the magnetic powder contains cobalt ferrite particle powder, the average particle size of the magnetic powder is preferably 25 nm or less, more preferably 8 nm or more and 23 nm or less. When the average particle size of the magnetic powder is 25 nm or less, good electromagnetic conversion characteristics (for example, C / N) can be obtained in a magnetic tape MT having a high recording density. On the other hand, when the average particle size of the magnetic powder is 8 nm or more, the dispersibility of the magnetic powder is further improved, and more excellent electromagnetic conversion characteristics (for example, C / N) can be obtained. When the magnetic powder contains a powder of cobalt ferrite particles, the average aspect ratio of the magnetic powder is the same as that of the above-described embodiment. Further, the method of calculating the average particle size and the average aspect ratio of the magnetic powder is also obtained in the same manner as in the above-described embodiment.

The average particle volume of the magnetic powder is preferably 15000 nm ³ or less, more preferably 500 nm ³ or more 12000 nm ³ or less. When the average particle volume of the magnetic powder is 15000 nm ³ or less, the same effect as when the average particle size of the magnetic powder is 25 nm or less can be obtained. On the other hand, when the average particle volume of the magnetic powder is 500 nm ³ 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 for calculating the average particle volume of the magnetic powder is the method for calculating the average particle volume of the magnetic powder in the above-described embodiment (the average particle volume when the ε iron oxide particles have a cubic shape or a substantially cubic shape). Calculation method) is the same.

(Modification 5)
The magnetic tape MT may be used for the library device. In this case, the library device has a configuration in which the tension applied in the longitudinal direction of the magnetic tape MT can be adjusted, and may include a plurality of recording / playback devices 50 according to the first embodiment.

(Modification 6)
The magnetic tape MT may be used as a servo writer. That is, the servo writer may adjust the tension in the longitudinal direction of the magnetic tape MT at the time of recording the servo signal or the like to keep the width of the magnetic tape MT constant or substantially constant. In this case, the servo writer may include a detection device for detecting the width of the magnetic tape MT, and adjust the tension in the longitudinal direction of the magnetic tape MT based on the detection result of the detection device.

(Modification 7)
The magnetic tape MT is not limited to the perpendicular recording type magnetic recording medium, and may be a horizontal recording type magnetic recording medium. In this case, needle-shaped magnetic powder such as metal magnetic powder may be used as the magnetic powder.

(Modification 8)
In the first embodiment described above, the case where the distance between the servo bands SB is used as the width-related information related to the magnetic tape MT at the time of data recording has been described, but the width of the magnetic tape MT may be used. ..

In this case, the control device 59 calculates the width W1 of the magnetic tape MT from the distance d1 between the servo bands SB at the time of data recording, and writes this width W1 in the cartridge memory 11 by the reader / writer 57.

The control device 59 reads the width W1 of the magnetic tape MT at the time of data recording from the cartridge memory 11 at the time of data reproduction, and reads the width W2 of the magnetic tape MT at the time of data reproduction from the distance d2 between the servo bands SB at the time of data reproduction. calculate. Then, the control device 59 calculates the difference ΔW between the width W1 of the magnetic tape MT at the time of data recording and the width W2 of the magnetic tape MT at the time of data reproduction, and determines whether or not the difference ΔW is within the specified value. To do.

When the difference ΔW is within the specified value, the control device 59 controls the rotational drive of the spindle 51 and the reel 52 so that the specified tension is maintained. On the other hand, when the difference ΔW is not within the specified value, the rotational drive of the spindle 51 and the reel 52 is controlled and the tension applied to the traveling magnetic tape MT is adjusted so that the difference ΔW is within the specified value.

(Modification 9)
In the second embodiment described above, the case where all of the temperatures Tm1, Tm2, humidity H1, H2, tension Tn1, Tn2, widths W1 and W2 are used as the data recording information has been described, but the data recording information is , Temperature Tm1, Tm2, Humidity H1, H2, Tension Tn1, Tn2, and Widths W1 and W2, or any combination of two or three.

Not only the information at the time of data recording (temperature Tm1, humidity H1, tension Tn1, width W1) but also the information at the time of data reproduction (temperature Tm2, humidity H2, tension Tn2, width W2) is stored in the cartridge memory 11. You may. For example, this information at the time of data reproduction is used when the data in the magnetic tape MT is reproduced at yet another opportunity after the data is reproduced.

(Modification example 10)
In the first and second embodiments described above, the case where the magnetic tape MT is a coating type magnetic tape in which the base layer, the recording layer and the like are produced by a coating step (wet process) has been described. The recording layer or the like may be a thin film type magnetic tape manufactured by a vacuum thin film manufacturing technique (dry process) such as sputtering. In the case of a thin film type magnetic tape, the average thickness t _m of the recording layer is preferably 9 [nm] ≤ t _m ≤ 90 [nm], more preferably 9 [nm] ≤ t _m ≤ 20 [nm], and even more. It is preferably 9 [nm] ≤ t _m ≤ 15 [nm]. When the average thickness t _m of the recording layer 43 is 9 [nm] ≤ t _m ≤ 90 [nm], the electromagnetic conversion characteristics can be improved.

Hereinafter, the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to these Examples.

In the following examples and comparative examples, the average thickness T _sub of the substrate, the average thickness t _{T of} the magnetic tape, the amount of dimensional change Δw in the width direction of the magnetic tape with respect to the tension change in the longitudinal direction of the magnetic tape, and the temperature expansion coefficient of the magnetic tape. alpha, humidity expansion coefficient of the magnetic tape beta, Poisson's ratio of the magnetic tape [rho, the longitudinal direction of the elastic limit of the magnetic tape sigma _MD, pulling speed V at the time of performing the elastic limit measured, the average thickness t _m of the recording layer, squareness S2, the average thickness t _{b of} the back layer, the surface roughness R _b of the back layer, and the interlayer friction coefficient μ between the magnetic surface and the back surface are values obtained by the measurement method described in the first embodiment. .. However, as will be described later, in Example 11, the tensile speed V when measuring the elastic limit value σ _MD in the longitudinal direction is set to a value different from that of the first embodiment.

[Example 1]
(Preparation process of paint for forming recording layer)
The coating material for forming a recording layer was prepared as follows. First, the first composition having the following composition was kneaded with an extruder. Next, the kneaded first composition and the second composition having the following composition were added to a stirring tank equipped with a disper and premixed. Subsequently, sandmill mixing was further performed and filtering was performed to prepare a coating material for forming a recording layer.

(First composition)
Powder of ε iron oxide nanoparticles (ε-Fe ₂ O ₃ crystal particles): 100 parts by mass Vinyl chloride resin (cyclohexanone solution 30% by mass): 10 parts by mass (degree of polymerization 300, Mn = 10000, OSO ₃ as polar group It contains K = 0.07 mmol / g and secondary OH = 0.3 mmol / g.)
Aluminum oxide powder: 5 parts by mass (α-Al ₂ O ₃ , average particle size 0.2 μm)
Carbon black: 2 parts by mass (manufactured by Tokai Carbon Co., Ltd., product name: Seast TA)

(Second composition)
Vinyl chloride resin: 1.1 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
n-Butyl stearate: 2 parts by mass Methyl ethyl ketone: 121.3 parts by mass Toluene: 121.3 parts by mass Cyclohexanone: 60.7 parts by mass

Finally, 4 parts by mass of polyisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 2 parts by mass of myristic acid were added as a curing agent to the coating material for forming a recording layer prepared as described above. did.

(Preparation process of paint for forming base layer)
The paint for forming the base layer was prepared as follows. First, the third composition having the following composition was kneaded with an extruder. Next, the kneaded third composition and the fourth composition having the following composition were added to a stirring tank equipped with a disper and premixed. Subsequently, sand mill mixing was further performed and filtering was performed to prepare a coating material for forming a base layer.

(Third composition)
Needle-shaped iron oxide powder: 100 parts by mass (α-Fe ₂ O ₃ , average major axis length 0.15 μm)
Vinyl chloride resin: 55.6 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
Carbon black: 10 parts by mass (average particle size 20 nm)

(4th composition)
Polyurethane resin UR8200 (manufactured by Toyo Spinning Co., Ltd.): 18.5 parts by mass n-butyl stearate: 2 parts by mass Methyl ethyl ketone: 108.2 parts by mass Toluene: 108.2 parts by mass Cyclohexanone: 18.5 parts by mass

Finally, to the base layer forming paint prepared as described above, polyisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.): 4 parts by mass and myristic acid: 2 parts by mass were added as a curing agent. did.

(Preparation process of paint for forming back layer)
The paint for forming the back layer was prepared as follows. The following raw materials were mixed in a stirring tank equipped with a disper and filtered to prepare a coating material for forming a back layer.
Carbon black (manufactured by Asahiyashiro, product name: # 80): 100 parts by mass Polyester polyurethane: 100 parts by mass (manufactured by Nippon Polyurethane Industry, product name: N-2304)
Methyl ethyl ketone: 500 parts by mass Toluene: 400 parts by mass Cyclohexanone: 100 parts by mass

(Film formation process)
Using the paint prepared as described above, an average thickness T _sub : 3.8 μm, which is a substrate (non-magnetic support), is averaged on a long poleethylene naphthalate film (hereinafter referred to as “PEN film”). An underlayer having a thickness of t _u : 1.0 μm and a recording layer having an average thickness of t _m : 90 nm were formed as follows. First, a base layer forming paint was applied onto the film and dried to form a base layer on the film. Next, a recording layer forming paint was applied onto the base layer and dried to form a recording layer on the base layer. When the coating material for forming the recording layer was dried, the magnetic powder was magnetically oriented in the thickness direction of the film by a solenoid coil. Further, the application time of the magnetic field to the coating material for forming the recording layer was adjusted, and the square ratio S2 in the thickness direction (vertical direction) of the magnetic tape was set to 65%.

Subsequently, a back layer having an average thickness of t _b : 0.6 μm was applied to the film on which the base layer and the recording layer were formed and dried. Then, the film on which the base layer, the recording layer, and the back layer were formed was cured. Subsequently, a calendar process was performed to smooth the surface of the recording layer. At this time, after adjusting the calendar processing conditions (temperature) so that the inter-story friction coefficient μ between the magnetic surface and the back surface is 0.5, re-hardening treatment is performed, and the magnetism has an average thickness t _T : 5.5 μm. The tape was obtained.

(Cutting process)
The magnetic tape obtained as described above was cut to a width of 1/2 inch (12.65 mm). As a result, the desired long magnetic tape having the characteristics shown in Tables 1 and 2 was obtained.

(Servo pattern recording process)
With respect to the magnetic tape obtained as described above, two or more rows of V-shaped magnetic patterns (servo patterns) were recorded parallel to the longitudinal direction.

(Cartridge manufacturing process)
First, as a cartridge, a cartridge having an area for writing tension adjustment information in the cartridge memory and capable of writing tension adjustment information to the area and reading tension adjustment information from the area was prepared. Next, a magnetic tape on which a row of magnetic patterns was recorded was wound around this cartridge. After that, the cartridge is loaded into the recording / playback device to record the specified data, and at the same time, two or more rows of the above-mentioned C-shaped magnetic pattern rows are simultaneously reproduced, or the above-mentioned C-shaped magnetic pattern is not recorded. Only two or more rows of magnetic pattern rows are reproduced, and the interval d1 of the magnetic pattern sequence at the time of data recording is measured at regular intervals (every 1 m interval) from the shape of the reproduced waveform of each column, and the position and the position are measured. The interval was written to the cartridge memory. As a result, the desired cartridge was obtained.

[Example 2]
The thickness of the PEN film was made thinner than that of Example 1 so that the amount of dimensional change Δw was 750 [ppm / N]. A cartridge was obtained in the same manner as in Example 1 except for this.

[Example 3]
The thickness of the PEN film was made thinner than in Example 1 so that the amount of dimensional change Δw was 800 [ppm / N], and the average thickness of the back layer and the base layer was made thinner. A cartridge was obtained in the same manner as in Example 1 except for this.

[Example 4]
The thickness of the PEN film was made thinner than in Example 1 so that the amount of dimensional change Δw was 800 [ppm / N], and the average thickness of the back layer and the base layer was made thinner. Further, the curing treatment conditions of the film on which the base layer, the recording layer, and the back layer were formed were adjusted. A cartridge was obtained in the same manner as in Example 1 except for this.

[Example 5]
A cartridge was obtained in the same manner as in Example 4 except that the composition of the coating material for forming the base layer was changed so that the coefficient of thermal expansion α was 8 [ppm / ° C.].

[Example 6]
A cartridge was obtained in the same manner as in Example 4 except that thin barrier layers were formed on both surfaces of the PEN film so that the coefficient of thermal expansion β was 3 [ppm /% RH].

[Example 7]
A cartridge was obtained in the same manner as in Example 4 except that the composition of the back layer forming paint was changed so that the Poisson's ratio ρ was 0.31.

[Example 8]
A cartridge was obtained in the same manner as in Example 4 except that the composition of the back layer forming paint was changed so that the Poisson's ratio ρ was 0.35.

[Example 9]
The same as in Example 7 except that the curing conditions of the film on which the base layer, the recording layer, and the back layer were formed were adjusted so that the elastic limit value σ _{MD in the} longitudinal direction was 0.80 [N]. I got a cartridge.

[Example 10]
Examples except that the curing conditions and re-curing conditions of the film on which the base layer, the recording layer, and the back layer were formed were adjusted so that the elastic limit value σ _{MD in the} longitudinal direction was 3.50 [N]. A cartridge was obtained in the same manner as in 7.

[Example 11]
A magnetic tape was obtained in the same manner as in Example 9. Then, the elastic limit sigma _MD of the obtained magnetic tape were measured by changing the pulling speed V when measuring the longitudinal direction of the elastic limit sigma _MD to 5 mm / min. As a result, the elastic limit value σ _MD in the longitudinal direction did not change with respect to the elastic limit value σ _MD (Example 9) in the longitudinal direction in which the tensile speed V was 0.5 mm / min, and was 0.80 [N]. there were.

[Example 12]
A cartridge was obtained in the same manner as in Example 7 except that the coating thickness of the coating material for forming the recording layer was changed so that the average thickness t _m of the recording layer was 40 nm.

[Example 13]
(SUL film formation process)
First, a CoZrNb layer (SUL) having an average thickness of 10 nm was formed on the surface of a long polymer film as a non-magnetic support under the following film forming conditions. A PEN film was used as the polymer film.
Film formation method: DC magnetron sputtering method Target: CoZrNb Target Gas type: Ar
Gas pressure: 0.1 Pa

(First seed layer film forming process)
Next, a TiCr layer (first seed layer) having an average thickness of 5 nm was formed on the CoZrNb layer under the following film forming conditions.
Sputtering method: DC magnetron Sputtering method Target: TiCr target Ultimate vacuum: 5 x 10 ^-5 Pa
Gas type: Ar
Gas pressure: 0.5 Pa

(Step of forming a second seed layer)
Next, a NiW layer (second seed layer) having an average thickness of 10 nm was formed on the TiCr layer under the following film forming conditions.
Sputtering method: DC magnetron Sputtering method Target: NiW target Ultimate vacuum: 5 x 10 ^-5 Pa
Gas type: Ar
Gas pressure: 0.5 Pa

(First base layer film forming process)
Next, a Ru layer (first base layer) having an average thickness of 10 nm was formed on the NiW layer under the following film forming conditions.
Sputtering method: DC magnetron Sputtering method Target: Ru Target Gas type: Ar
Gas pressure: 0.5 Pa

(Step of forming the second base layer)
Next, a Ru layer (second base layer) having an average thickness of 20 nm was formed on the Ru layer under the following film forming conditions.
Sputtering method: DC magnetron Sputtering method Target: Ru Target Gas type: Ar
Gas pressure: 1.5 Pa

(Recording process of recording layer)
Next, a (CoCrPt)-(SiO ₂ ) layer (recording layer) having an average thickness of t _m : 9 nm was formed on the Ru layer under the following film forming conditions.
Film formation method: DC magnetron sputtering method Target: (CoCrPt)-(SiO ₂ ) Target gas type: Ar
Gas pressure: 1.5 Pa

(Protective layer film formation process)
Next, a carbon layer (protective layer) having an average thickness of 5 nm was formed on the recording layer under the following film forming conditions.
Film formation method: DC magnetron sputtering method Target: Carbon target Gas type: Ar
Gas pressure: 1.0 Pa

(Lubrication layer film formation process)
Next, a lubricant was applied on the protective layer to form a lubricating layer.

(Back layer film formation process)
Next, a back layer forming paint was applied to the surface opposite to the recording layer and dried to form a back layer having an average thickness t _b : 0.3 μm. As a result, a magnetic tape having an average thickness of t _T : 4.0 μm was obtained.

(Cutting process)
The magnetic tape obtained as described above was cut to a width of 1/2 inch (12.65 mm). As a result, the desired long magnetic tape having the characteristics shown in Tables 1 and 2 was obtained.

A servo pattern was recorded and a cartridge was produced in the same manner as in Example 1 except that the magnetic tape obtained as described above was used to obtain a cartridge.

[Example 14]
A cartridge was obtained in the same manner as in Example 7 except that the coating thickness of the back layer forming paint was changed so that the average thickness t _b of the back layer was 0.3 μm.

[Example 15]
Cartridge in the same manner as in Example 7 except that the composition of the paint for forming the back layer (the amount of the inorganic filler (carbon black) added) was changed so that the surface roughness R _b of the back layer was 3 [nm]. Got

[Example 16]
A cartridge was obtained in the same manner as in Example 7 except that the calendar processing conditions (temperature) were adjusted so that the inter-story friction coefficient μ between the magnetic surface and the back surface was 0.2.

[Example 17]
A cartridge was obtained in the same manner as in Example 7 except that the calendar processing conditions (temperature) were adjusted so that the inter-story friction coefficient μ between the magnetic surface and the back surface was 0.8.

[Example 18]
A cartridge was obtained in the same manner as in Example 7 except that the coating thickness of the coating material for forming the recording layer was changed so that the average thickness t _m of the recording layer was 110 nm.

[Example 19]
Cartridge in the same manner as in Example 7 except that the composition of the paint for forming the back layer (the amount of the inorganic filler (carbon black) added) was changed so that the surface roughness R _b of the back layer was 7 [nm]. Got

[Example 20]
A cartridge was obtained in the same manner as in Example 7 except that the calendar processing conditions (temperature) were adjusted so that the inter-story friction coefficient μ between the magnetic surface and the back surface was 0.18.

[Example 21]
A cartridge was obtained in the same manner as in Example 7 except that the calendar processing conditions (temperature) were adjusted so that the inter-story friction coefficient μ between the magnetic surface and the back surface was 0.82.

[Example 22]
A cartridge was obtained in the same manner as in Example 7 except that the application time of the magnetic field to the paint for forming the magnetic layer was adjusted and the square ratio S2 in the thickness direction (vertical direction) of the magnetic tape was set to 73%.

[Example 23]
A cartridge was obtained in the same manner as in Example 7 except that the application time of the magnetic field to the paint for forming the magnetic layer was adjusted and the square ratio S2 in the thickness direction (vertical direction) of the magnetic tape was set to 80%.

[Example 24]
Examples except that the curing conditions and re-curing conditions of the film on which the base layer, the recording layer, and the back layer were formed were adjusted so that the elastic limit value σ _{MD in the} longitudinal direction was 5.00 [N]. A cartridge was obtained in the same manner as in 10.

[Example 25]
A cartridge was obtained in the same manner as in Example 7 except that barium ferrite (BaFe ₁₂ O ₁₉ ) nanoparticles were used instead of ε iron oxide nanoparticles.

[Example 26]
A PEN film having a stretching strength in the width direction higher than that of the PEN film of Example 7 was used so that the amount of dimensional change Δw was 670 [ppm / N]. A cartridge was obtained in the same manner as in Example 25 except for this.

[Example 27]
A PEN film having a stretching strength in the width direction higher than that of the PEN film of Example 1 was used so that the amount of dimensional change Δw was 650 [ppm / N]. A cartridge was obtained in the same manner as in Example 1 except for this.

[Comparative Example 1]
A PEN film having an average thickness T _sub of 4.0 μm, which had a higher stretching strength in the width direction than the PEN film of Example 26, was used so that the amount of dimensional change Δw was 630 [ppm / N]. A cartridge was obtained in the same manner as in Example 1 except for this.

[Comparative Example 2]
A PEN film having an average thickness T _sub of 5.0 μm, which had a higher stretching strength in the width direction than the PEN film of Example 26, was used so that the amount of dimensional change Δw was 500 [ppm / N]. The average thickness t _b of the back layer was set to 0.4 μm. A cartridge was obtained in the same manner as in Example 1 except for this.

[Reference Examples 1-26, Comparative Examples 3-5]
First, in the same manner as in Examples 1 to 27 and Comparative Examples 1 and 2, a magnetic tape was obtained, and then a row of magnetic patterns in a C shape was recorded on the magnetic tape. Subsequently, a cartridge was prepared in which tension adjustment information could not be written and tension adjustment information could not be read. Next, a magnetic tape on which a row of magnetic patterns was recorded was wound around this cartridge. After that, the cartridge was loaded into the recording / playback device, and the specified data was recorded. As a result, the desired cartridge was obtained.

(Judgment of change in tape width (1))
First, the cartridges of Examples 1 to 27 and Comparative Examples 1 and 2 were loaded into the recording / reproducing device, and the magnetic tape was regenerated and reciprocated while adjusting the tension applied in the longitudinal direction of the magnetic tape. At this time, the tension was adjusted by the recording / playback device as follows. That is, two or more columns of the H-shaped magnetic pattern sequence are reproduced together with the data, and the interval d2 of the magnetic pattern sequence at the time of data reproduction is continuously determined from the shape of the reproduced waveform of each column (the point where the servo position information is present). Every time (specifically, every 6 mm) was measured, the interval d1 of the magnetic pattern sequence at the time of data recording was read from the cartridge memory. Then, the rotational drive of the spindle drive device and the reel drive device is controlled so that the interval d2 of the magnetic pattern strings during data reproduction approaches the interval d1 of the magnetic pattern strings during data recording, and the tension in the longitudinal direction of the magnetic tape is controlled. Was adjusted automatically. All the measured values for one round trip of the interval of the magnetic pattern string are set as "measured magnetic pattern string interval d2", and the maximum value of the difference between this and the "known magnetic pattern string interval d1 when traveling in advance". Was defined as "change in tape width".

In addition, the reciprocating travel by the recording / reproducing device was performed in a constant temperature and humidity chamber. The reciprocating speed was 5 m / sec. The temperature and humidity during the reciprocating travel are independent of the above reciprocating travel, with a temperature range of 10 ° C to 45 ° C and a relative humidity range of 10% to 80%, and a pre-configured environmental change program (10 ° C 10% → 29 ° C) Repeat 80% → 10 ° C. 10% twice. Change from 10 ° C. 10% to 29 ° C. 80% in 2 hours, and gradually change from 29 ° C. 80% to 10 ° C. 10% in 2 hours). And repeatedly changed.

This evaluation was repeated until the "pre-assembled environmental change program" was completed. After the evaluation is completed, the average value (simple average) is calculated using all the absolute values of the "change in tape width" obtained at each round trip, and that value is the "effective amount of change in tape width" of the tape. And said. Judgment was made for each cartridge according to the deviation from the ideal of this "effective amount of change in tape width" (smaller is desirable), and eight levels of judgment values were given. The evaluation "8" indicates the most desirable judgment result, and the evaluation "1" indicates the most undesired judgment result. The following states are observed when the magnetic tape having any of the above eight grades is evaluated.
8: No abnormality occurs 7: A slight increase in the error rate is observed during driving 6: A severe increase in the error rate is observed during driving 5: The servo signal cannot be read during driving and is mild (1 to 1) 2) reloading is required 4: Servo signal cannot be read during driving and moderate (within 10 times) reloading is required 3: Servo signal cannot be read during driving and severe (more than 10 times) reloading is required Such 2: Servo cannot be read and sometimes stops due to a system error 1: Servo cannot be read and stops immediately due to a system error

(Judgment of change in tape width (2))
The cartridges of Reference Examples 1 to 26 and Comparative Examples 1 to 3 were loaded into the recording / reproducing device, and the magnetic tape was regenerated and reciprocated while adjusting the tension applied in the longitudinal direction of the magnetic tape. At this time, the tension was adjusted by the recording / playback device as follows. That is, two or more rows of the V-shaped magnetic pattern trains were reproduced together with the data, and the interval d2 of the magnetic pattern trains at the time of data reproduction was continuously measured from the shape of the reproduced waveform of each row. Then, the rotational drive of the spindle drive device and the reel drive device was controlled so that the interval d2 of the magnetic pattern train at the time of data reproduction approaches the predetermined interval d3, and the tension in the longitudinal direction of the magnetic tape was automatically adjusted. Other than this, in the same manner as the judgment of the amount of change in the tape width (1), the judgment according to the deviation from the ideal of the "effective amount of change in the tape width" is performed for each cartridge, and there are eight stages. Judgment values were given respectively. The specified interval d3 is an interval of a known magnetic pattern sequence that serves as a reference when adjusting the tension in the longitudinal direction of the magnetic tape, and is stored in advance in the control device of the recording / reproducing device.

(Evaluation of electromagnetic conversion characteristics)
First, using a loop tester (manufactured by Microphysics), the reproduction signals of the magnetic tapes used in the cartridges of Examples 1 to 27 and Comparative Examples 1 and 2 were acquired. The acquisition conditions for the reproduction signal are shown below.
head: GMR head
speed: 2m / s
signal: Single recording frequency (10MHz)
Recording current: Optimal recording current

Next, the reproduced signal was captured by a spectrum analyzer with a span (SPAN) of 0 to 20 MHz (resolution band width = 100 kHz, VBW = 30 kHz). Next, the peak of the captured spectrum is defined as the signal amount S, the floor noise excluding the peak is integrated to obtain the noise amount N, and the ratio S / N of the signal amount S and the noise amount N is SNR (Signal-to-). Noise Ratio). Next, the obtained SNR was converted into a relative value (dB) based on the SNR of Comparative Example 1 as a reference medium. Next, using the SNR (dB) obtained as described above, the quality of the electromagnetic conversion characteristics was determined as follows.
Good: The SNR of the magnetic tape is equal to or exceeds the SNR (= 0 (dB)) of the evaluation reference sample (Comparative Example 1) or exceeds this SNR (= 0 (dB)).
Defective: The SNR of the magnetic tape is less than the SNR (= 0 (dB)) of the evaluation reference sample (Comparative Example 1).

(Evaluation of winding deviation)
First, a cartridge sample after the above-mentioned "determination of change in tape width (1)" was prepared. Next, the reel on which the tape was wound was taken out from the cartridge sample, and the end face of the wound tape was visually observed. The reel has a flange, and at least one of the flanges is transparent or translucent, and the internal tape winding state can be observed through the flange.

As a result of observation, if the end face of the tape is not flat and there is a step or the tape pops out, it is assumed that the tape is miswound. In addition, the more these steps and the protrusion of the tape were observed, the worse the "winding deviation" was. The above determination was made for each sample. The winding misalignment state of each sample was compared with the winding misalignment state of Comparative Example 1 as a reference medium, and the quality was judged as follows.
Good: When the winding misalignment of the sample is equal to or less than the winding misalignment of the reference sample (Comparative Example 1) Poor: When the winding misalignment of the sample is larger than that of the reference sample (Comparative Example 1)

Tables 1 and 2 show the configurations and evaluation results of the cartridges of Examples 1 and 27 and Comparative Examples 1 and 2.

Table 3 shows the evaluation results of the cartridges of Reference Examples 1 to 26 and Comparative Examples 3 to 5.

In addition, each symbol in Tables 1 and 2 means the following measured values.
T _sub : Average thickness of the substrate t _T : Thickness of the magnetic tape Δw: Dimensional change in the width direction of the magnetic tape with respect to the tension change in the longitudinal direction of the magnetic tape α: Temperature expansion coefficient of the magnetic tape β: Humidity expansion coefficient of the magnetic tape [rho: Poisson's ratio of the magnetic tape sigma _MD: longitudinal direction of the elastic limit of the magnetic tape V: pulling speed when performing the elastic limit measured t _m: average thickness of the recording layer R2: in the magnetic tape in the thickness direction (vertical direction) Square ratio _tu : Average thickness of base layer t _b : Average thickness of back layer R _b : Surface roughness of back layer μ: Interlayer friction coefficient between magnetic surface and back surface

The following can be seen from Tables 1 to 4.
From the comparison of the evaluation results of Examples 1 to 3, 26, 27, Comparative Examples 1 and 2, etc., the amount of dimensional change Δw of the magnetic tape was set to 650 [ppm / N] ≦ Δw and stored in the cartridge memory at the time of data recording. It can be seen that the deviation from the ideal of the "effective amount of change in the tape width" can be suppressed by adjusting the tension applied in the longitudinal direction of the magnetic tape by using the tension adjustment information.

The following can be seen from the comparison of the evaluation results of Examples 1, 3 and 26, 27, Comparative Examples 1 and 2, and Reference Examples 1 to 3, Reference Example 26, and Comparative Examples 3 to 5. That is, by adjusting the tension applied in the longitudinal direction of the magnetic tape by using the tension adjustment information stored in the cartridge memory at the time of data recording, deviation from the ideal of "effective tape width change amount" is suppressed. Therefore, the lower limit of the dimensional change amount Δw required for this can be lowered from 670 [ppm / N] to 650 [ppm / N] ≦ Δw.

From the comparison of the evaluation results of Examples 1 to 3, 26, 27, Comparative Examples 1 and 2, etc., from the viewpoint of suppressing the deviation from the ideal of "effective tape width change amount", the dimensional change amount Δw is , Preferably 670 [ppm / N] ≦ Δw, more preferably 680 [ppm / N] ≦ Δw, even more preferably 700 [ppm / N] ≦ Δw, and particularly preferably 750 [ppm / N]. It can be seen that N] ≦ Δw, and most preferably 800 [ppm / N] ≦ Δw.

From the viewpoint of suppressing the deviation from the ideal of "effective tape width change amount" from the comparison of the evaluation results of Reference Examples 3 to 5, the coefficient of thermal expansion α is 6 [ppm / ° C] ≤ α ≤ 8. It can be seen that [ppm / ° C.] is preferable.
From the viewpoint of suppressing the deviation from the ideal of "effective tape width change amount" from the comparison of the evaluation results of Reference Examples 3, 4, 6 and the like, the humidity expansion coefficient β is β ≦ 5 [ppm /% RH. ] Is preferable.

From the comparison of the evaluation results of Reference Examples 6 to 8 and the like, it is preferable that the Poisson's ratio ρ is 0.3 ≦ ρ from the viewpoint of suppressing the deviation of the “effective amount of change in tape width” from the ideal. I understand.
From the comparison of the evaluation results of Reference Examples 7, 9, 10, 24, etc., from the viewpoint of suppressing the deviation from the ideal of "effective tape width change amount", the elastic limit value σ _{MD in the} longitudinal direction is 0. It can be seen that it is preferable that 8.8 [N] ≤ σ _MD .
It can be seen that the elastic limit value σ _MD of Examples 9 and 11 does not depend on the tensile speed V when the elastic limit measurement is performed.

In Examples 1 to 27, the "determination of change in tape width (1)" is performed regardless of the values of the coefficient of thermal expansion α, the coefficient of thermal expansion β, the Poisson's ratio ρ, and the elastic limit value σ _{MD in} the longitudinal direction. The result is "8". This is because the determination of the amount of change in the tape width is evaluated in eight stages. When a more detailed evaluation (for example, evaluation in 10 stages) is performed, the same in Examples 1 to 27 as in Reference Examples 1 to 26, the coefficient of thermal expansion α, the coefficient of thermal expansion β, the Poisson's ratio ρ, and the longitudinal direction In the numerical range of the elastic limit value σ _MD of, it is presumed that an evaluation result that can further suppress the deviation of the “effective amount of change in tape width” from the ideal can be obtained.

From the comparison of the evaluation results of Examples 9, 12, 18 and the like, it can be seen that the average thickness t _m of the recording layer is preferably t _m ≤ 90 [nm] from the viewpoint of improving the electromagnetic conversion characteristics.

From the comparison of the evaluation results of Examples 7, 15, 19 and the like, from the viewpoint of improving the electromagnetic conversion characteristics, it is preferable that the surface roughness R _b of the back layer is R _b ≤ 6.0 [nm]. I understand.

From the comparison of the evaluation results of Examples 7, 16, 17, 21 and the like, from the viewpoint of suppressing the winding deviation, the inter-story friction coefficient μ between the magnetic surface and the back surface is 0.20 ≦ μ ≦ 0.80. It turns out to be preferable.

From the comparison of the evaluation results of Examples 7, 22, 23 and the like, it can be seen that the square ratio S2 of the magnetic tape in the vertical direction is preferably 80% or more from the viewpoint of improving the electromagnetic conversion characteristics.

From the comparison of the evaluation results of Examples 7, 25, 26 and the like, even when barium ferrite nanoparticles are used as the magnetic particles, each parameter such as the amount of dimensional change Δw, the coefficient of thermal expansion α and the coefficient of thermal expansion β is adjusted. As a result, it can be seen that the same evaluation results as when ε-iron oxide nanoparticles are used as the magnetic particles can be obtained.

Although the embodiments and modifications of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present disclosure are possible. Is.

For example, the configurations, methods, processes, shapes, materials, numerical values, etc. given in the above-described embodiments and modifications are merely examples, and if necessary, different configurations, methods, processes, shapes, materials, numerical values, etc. May be used. Further, the chemical formulas of the compounds and the like are typical, and the general names of the same compounds are not limited to the stated valences and the like.

In addition, the configurations, methods, processes, shapes, materials, numerical values, and the like of the above-described embodiments and modifications can be combined with each other without departing from the gist of the present disclosure.

Further, in the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step may be replaced with the upper limit value or the lower limit value of the numerical range of another step. Unless otherwise specified, the materials exemplified in the present specification may be used alone or in combination of two or more.

The present disclosure may also adopt the following configuration.
(1)
With a tape-shaped magnetic recording medium
A communication unit that communicates with the recording / playback device,
Memory and
The information received from the recording / playback device via the communication unit is stored in the storage unit, and the information is read from the storage unit in response to the request of the recording / playback device, and the information is read through the communication unit. Equipped with a control unit that transmits to the recording / playback device
The information includes adjustment information for adjusting the tension applied in the longitudinal direction of the magnetic recording medium.
The average thickness t _T of the magnetic recording medium is t _T ≤ 5.5 [μm].
A cartridge in which the amount of dimensional change Δw in the width direction with respect to the tension change in the longitudinal direction of the magnetic recording medium is 650 [ppm / N] ≦ Δw.
(2)
The cartridge according to (1), wherein the dimensional change amount Δw is 700 [ppm / N] ≦ Δw.
(3)
The cartridge according to (1), wherein the dimensional change amount Δw is 750 [ppm / N] ≦ Δw.
(4)
The cartridge according to (1), wherein the dimensional change amount Δw is 800 [ppm / N] ≦ Δw.
(5)
The cartridge according to any one of (1) to (4), wherein the adjustment information is acquired at the time of data recording on the magnetic recording medium.
(6)
The cartridge according to (5), wherein the adjustment information includes width-related information related to the width of the magnetic recording medium.
(7)
The cartridge according to (6), wherein the width-related information is distance information between adjacent servo tracks or width information of the magnetic recording medium.
(8)
The cartridge according to any one of (5) to (7), wherein the adjustment information includes environmental information around the magnetic recording medium.
(9)
The cartridge according to (8), wherein the environmental information includes temperature information around the magnetic recording medium.
(10)
The cartridge according to (8) or (9), wherein the environmental information includes humidity information around the magnetic recording medium.
(11)
The cartridge according to any one of (5) to (10), wherein the adjustment information includes tension information of the magnetic recording medium.
(12)
The storage unit
A first storage area for storing the first information conforming to the magnetic tape standard, and
It has a second storage area for storing second information other than the first information, and has a second storage area.
The cartridge according to any one of (1) to (11), wherein the second information includes the adjustment information.
(13)
The cartridge according to any one of (1) to (12), wherein the coefficient of thermal expansion α of the magnetic recording medium is 6 [ppm / ° C] ≤ α ≤ 8 [ppm / ° C].
(14)
The cartridge according to any one of (1) to (13), wherein the coefficient of thermal expansion β of the magnetic recording medium is β ≦ 5 [ppm /% RH].
(15)
The cartridge according to any one of (1) to (14), wherein the Poisson's ratio ρ of the magnetic recording medium is 0.3 ≦ ρ.
(16)
The cartridge according to any one of (1) to (15), wherein the elastic limit value σ _{MD in} the longitudinal direction of the magnetic recording medium is 0.8 [N] ≦ σ _MD .
(17)
The cartridge according to any one of (1) to (16), wherein the magnetic recording medium is configured to form 6000 or more data tracks.
(18)
The cartridge according to any one of (1) to (17), which conforms to the standard of LTO9 or later.
(19)
The magnetic recording medium includes a recording layer and
The cartridge according to any one of (1) to (18), wherein the average thickness t _{m of the} recording layer is 9 [nm] ≤ t _m ≤ 90 [nm].
(20)
The cartridge according to (19), wherein the average thickness t _{m of the} recording layer is 35 [nm] ≤ t _m ≤ 90 [nm].
(21)
With a back layer
The cartridge according to any one of (1) to (20), wherein the average thickness t _{b of the} back layer is t _b ≦ 0.6 [μm].
(22)
With a back layer
The cartridge according to any one of (1) to (21), wherein the surface roughness R _{b of the} back layer is R _b ≤ 6.0 [nm].
(23)
It has a magnetic surface and a back surface that is opposite to the magnetic surface.
The cartridge according to any one of (1) to (22), wherein the interlayer friction coefficient μ between the magnetic surface and the back surface is 0.20 ≦ μ ≦ 0.80.
(24)
The magnetic recording medium includes a recording layer containing magnetic powder.
The cartridge according to any one of (1) to (23), wherein the magnetic powder contains ε-iron oxide, hexagonal ferrite or Co-containing spinel ferrite.
(25)
The cartridge according to any one of (1) to (24), wherein the square ratio of the magnetic recording medium in the vertical direction is 65% or more.
(26)
The cartridge according to any one of (1) to (25), wherein the square ratio of the magnetic recording medium in the vertical direction is 70% or more.
(27)
Described in any one of (1) to (26), wherein the coercive force Hc1 in the vertical direction of the magnetic recording medium and the coercive force Hc2 in the longitudinal direction of the magnetic recording medium satisfy the relationship of Hc2 / Hc1 ≦ 0.8. Cartridge.
(28)
The magnetic recording medium includes a magnetic layer containing a lubricant.
The magnetic layer has a surface provided with a large number of holes and has a surface.
The cartridge according to any one of (1) to (27), wherein the total BET specific surface area of the magnetic recording medium in the state where the lubricant is removed is 3.5 m ² / mg or more.
(29)
With a tape-shaped magnetic recording medium
A storage unit having an area for writing adjustment information for adjusting the tension applied in the longitudinal direction of the magnetic recording medium is provided.
The average thickness t _T of the magnetic recording medium is t _T ≤ 5.5 [μm].
A cartridge in which the amount of dimensional change Δw in the width direction with respect to the tension change in the longitudinal direction of the magnetic recording medium is 650 [ppm / N] ≦ Δw.
(30)
A cartridge memory used for a tape-shaped magnetic recording medium.
A communication unit that communicates with the recording / playback device,
Memory and
The information received from the recording / playback device via the communication unit is stored in the storage unit, and the information is read from the storage unit in response to the request of the recording / playback device, and the information is read through the communication unit. Equipped with a control unit that transmits to the recording / playback device
The information is a cartridge memory including adjustment information for adjusting the tension applied in the longitudinal direction of the magnetic recording medium.
(31)
A cartridge memory used for a tape-shaped magnetic recording medium.
A cartridge memory including a storage unit having an area for writing adjustment information for adjusting the tension applied in the longitudinal direction of the magnetic recording medium.

10 Cartridge 11 Cartridge memory 31 Antenna coil 32 Rectifier / power supply circuit 33 Clock circuit 34 Detection / modulation circuit 35 Controller 36 Memory 36A First storage area 36B Second storage area 41 Base 42 Base layer 43 Recording layer 44 Back layer 50, 50A recording / playback device 51 spindle 52 reel 53 spindle drive device 54 reel drive device 55 guide roller 56 head unit 57 reader / writer 58 communication interface 59 control device 60 thermometer 61 hygrometer 100, 100A recording / playback system MT magnetic tape

In order to solve the above-mentioned problems, the first disclosure is
Widthwise dimension variation [Delta] w of the magnetic recording medium with respect to the longitudinal direction of the tension change in the magnetic recording medium, Ri 650 [ppm / N] ≦ Δw ≦ 20000 [ppm / N] der,
It is a magnetic recording medium in which the square ratio of the magnetic recording medium in the vertical direction is 65% or more .
The second disclosure is
The amount of dimensional change Δw in the width direction of the magnetic recording medium with respect to the tension change in the longitudinal direction of the magnetic recording medium is 650 [ppm / N] ≦ Δw ≦ 20000 [ppm / N].
A magnetic recording medium having a coercive force Hc1 in the vertical direction of the magnetic recording medium of 220 kA / m or more and 310 kA / m or less.
The third disclosure is
The amount of dimensional change Δw in the width direction of the magnetic recording medium with respect to the tension change in the longitudinal direction of the magnetic recording medium is 650 [ppm / N] ≦ Δw ≦ 20000 [ppm / N].
A magnetic recording medium in which the coercive force Hc1 in the vertical direction and the coercive force Hc2 in the longitudinal direction of the magnetic recording medium satisfy the relationship of Hc2 / Hc1 ≦ 0.8.
The fourth disclosure is
The amount of dimensional change Δw in the width direction of the magnetic recording medium with respect to the tension change in the longitudinal direction of the magnetic recording medium is 650 [ppm / N] ≦ Δw ≦ 20000 [ppm / N].
It has a magnetic surface and a back surface that is opposite to the magnetic surface.
This is a magnetic recording medium in which the inter-story friction coefficient μ between the magnetic surface and the back surface is 0.20 ≦ μ ≦ 0.80.

The fifth disclosure is
With any of the magnetic recording media of the first to fourth disclosures,
Cartridge case and
Cartridge memory and
Including reels
A cartridge in which the magnetic recording medium is housed in a cartridge case while being wound on a reel.

Claims (34)

The average thickness t _T is t _T ≤ 5.5 [μm].
A magnetic recording medium in which the amount of dimensional change Δw in the width direction with respect to the change in tension in the longitudinal direction is 700 [ppm / N] ≦ Δw. The magnetic recording medium according to claim 1, wherein the amount of dimensional change Δw is 750 [ppm / N] ≦ Δw. The magnetic recording medium according to claim 1 or 2, wherein the amount of dimensional change Δw is 800 [ppm / N] ≦ Δw. The magnetic recording medium according to any one of claims 1 to 3, wherein the amount of dimensional change Δw is Δw ≦ 20000 [ppm / N]. The magnetic recording medium according to any one of claims 1 to 4, wherein the coefficient of thermal expansion α is 6 [ppm / ° C] ≤ α ≤ 8 [ppm / ° C]. The magnetic recording medium according to any one of claims 1 to 5, wherein the humidity expansion coefficient β is β ≦ 5 [ppm /% RH]. The magnetic recording medium according to any one of claims 1 to 6, wherein the Poisson's ratio ρ is 0.3 ≦ ρ. The magnetic recording medium according to any one of claims 1 to 7, wherein the elastic limit value σ _{MD in the} longitudinal direction is 0.8 [N] ≤ σ _MD . The magnetic recording medium according to claim 8, wherein the elastic limit value σ _MD does not depend on the velocity V when performing the elastic limit measurement. With the base
The magnetic recording medium according to any one of claims 1 to 9, further comprising a recording layer provided on the substrate. The magnetic recording medium according to claim 10, wherein the recording layer is vertically oriented. The magnetic recording medium according to claim 10 or 11, wherein the recording layer is a vacuum thin film. The magnetic recording medium according to claim 12, wherein the average thickness t _{m of the} recording layer is 9 [nm] ≤ t _m ≤ 90 [nm]. The magnetic recording medium according to claim 10 or 11, wherein the recording layer contains magnetic powder. The magnetic recording medium according to claim 14, wherein the average thickness t _{m of the} recording layer is 35 [nm] ≤ t _m ≤ 90 [nm]. The magnetic recording medium according to claim 14 or 15, wherein the magnetic powder contains ε-iron oxide magnetic powder, hexagonal ferrite magnetic powder, or Co-containing spinel ferrite magnetic powder. The magnetic recording medium according to any one of claims 10 to 16, wherein the recording layer has five or more servo bands. The magnetic recording medium according to claim 17, wherein the ratio of the total area of the servo band to the surface area of the recording layer is 4.0% or less. The magnetic recording medium according to claim 17 or 18, wherein the width of the servo band is 95 μm or less. The magnetic recording medium according to any one of claims 10 to 19, wherein the recording layer is configured to be capable of forming 6000 or more data tracks. The recording layer is configured so that a plurality of data tracks can be formed.
The magnetic recording medium according to any one of claims 10 to 19, wherein the width of the data track is 3.0 μm or less. The magnetic recording medium according to any one of claims 10 to 21, wherein the recording layer is configured to be capable of recording data so that the minimum value of the magnetization reversal distance L is 50 nm or less. The magnetic recording medium according to any one of claims 10 to 22, wherein the average thickness of the substrate is 4.2 μm or less. The magnetic recording medium according to any one of claims 10 to 23, wherein the substrate contains polyesters. With a back layer
The magnetic recording medium according to any one of claims 1 to 24, wherein the average thickness t _{b of the} back layer is t _b ≦ 0.6 [μm]. With a back layer
The magnetic recording medium according to any one of claims 1 to 24, wherein the surface roughness R _{b of the} back layer is R _b ≤ 6.0 [nm]. It has a magnetic surface and a back surface that is opposite to the magnetic surface.
The magnetic recording medium according to any one of claims 1 to 26, wherein the interlayer friction coefficient μ between the magnetic surface and the back surface is 0.20 ≦ μ ≦ 0.80. The magnetic recording medium according to any one of claims 1 to 27, wherein the square ratio in the vertical direction is 65% or more. The magnetic recording medium according to any one of claims 1 to 28, wherein the square ratio in the vertical direction is 70% or more. The magnetic recording medium according to any one of claims 1 to 29, which conforms to the standard of LTO9 or later. The magnetic recording medium according to any one of claims 1 to 30, wherein the coercive force Hc1 in the vertical direction is 220 kA / m or more and 310 kA / m or less. The magnetic recording medium according to any one of claims 1 to 31, wherein the coercive force Hc1 in the vertical direction and the coercive force Hc2 in the longitudinal direction satisfy the relationship of Hc2 / Hc1 ≦ 0.8. The magnetic recording medium according to any one of claims 1 to 32, which is used for a cartridge including a storage unit having an area for writing adjustment information for adjusting the tension applied in the longitudinal direction of the magnetic recording medium. The magnetic recording medium according to any one of claims 1 to 32, which is used in a recording / reproducing device for storing adjustment information for adjusting the tension applied in the longitudinal direction of the magnetic recording medium.

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