Magnetic tape cartridge and magnetic recording / reproducing device

Abstract

To satisfactorily perform recording and / or playback in recording and / or playback of data for a magnetic tape after storage accommodated in a magnetic tape cartridge, and adjust tension applied in a longitudinal direction of the magnetic tape to control a dimension in a width direction of the magnetic tape, thereby improving running stability in performing recording and / or playback.SOLUTION: A magnetic tape cartridge accommodating a magnetic tape and a magnetic recording playback device including the same are provided. In the magnetic tape, the maximum value of an amount of deformation of the magnetic tape after one-year storage in five environments is 0.50 μm or less. A ratio of a change in the amount of deformation of the magnetic tape to a change in relative humidity obtained from the five amounts of deformation of the magnetic tape is 0.0001 μm / % or more and 0.0500 μm / % or less. A ratio of a change in the amount of deformation of the magnetic tape to a change in a temperature obtained from the five amounts of deformation of the magnetic tape is 0.0010 μm / °C or more and 0.1000 μm / °C or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a magnetic tape cartridge and a magnetic recording / reproducing device. [Background technology]

[0002] Magnetic recording media include tape-shaped and disk-shaped ones, and tape-shaped magnetic recording media, that is, magnetic tapes, are primarily used for various data storage applications (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6590104 specification Summary of the Invention [Problem to be solved by the invention]

[0004] Data is usually recorded on a magnetic tape by running the magnetic tape in a magnetic recording and reproducing device (commonly called a "drive") and recording data on the data band by making a magnetic head follow the data band of the magnetic tape. This forms a data track on the data band. When reproducing the recorded data, the magnetic tape is run in the magnetic recording and reproducing device and the magnetic head follows the data band of the magnetic tape to read the data recorded on the data band. After such recording or reproduction, the magnetic tape is wound on a reel (hereinafter referred to as a "cartridge reel") in a magnetic tape cartridge and stored until the next recording and / or reproduction is performed.

[0005] In order to improve the accuracy with which the magnetic head tracks the data band of the magnetic tape during the above-described recording and / or reproduction, a system that performs head tracking using a servo signal (hereinafter referred to as a "servo system") has been put into practical use. Furthermore, the width direction dimension of the magnetic tape is controlled by acquiring width direction dimensional information of the magnetic tape while it is running using a servo signal, and adjusting the tension applied to the magnetic tape in the longitudinal direction according to the acquired dimensional information (see paragraph 0170 of Patent Document 1 as an example). The above tension adjustment is considered to contribute to suppressing the occurrence of phenomena such as overwriting of recorded data and playback failure, which occur when the magnetic head for recording or playing back data is shifted from the target track position due to the width deformation of the magnetic tape during recording or playback. Furthermore, when the magnetic tape is run in a magnetic recording and playback device to record and / or play back data while performing such tension adjustment, the high running stability of the magnetic tape is expected to further suppress the occurrence of the above phenomena.

[0006] Furthermore, when recording and / or reproducing is performed after the above storage, if the magnetic head for recording and / or reproducing data deviates from the target track position due to deformation of the magnetic tape and performs recording and / or reproducing of data, phenomena such as overwriting of recorded data and reproduction failure may occur. Meanwhile, in the field of data storage, there has been an increasing need in recent years for long-term storage of data, known as archives. However, in general, the longer the storage period, the more likely the magnetic tape is to deform. Therefore, it is expected that there will be an even greater demand in the future for suppressing the occurrence of the above phenomena after storage.

[0007] In view of the above, one aspect of the present invention is to provide a method for manufacturing a semiconductor device comprising: To enable good recording and / or reproduction of data on a magnetic tape after the magnetic tape has been housed in a magnetic tape cartridge and stored; and To improve running stability during recording and / or playback by controlling the width direction of the magnetic tape by adjusting the tension applied to the magnetic tape in the longitudinal direction; The purpose is to: [Means for solving the problem]

[0008] One aspect of the present invention is A magnetic tape cartridge in which a magnetic tape is wound around a cartridge reel, The magnetic tape has a non-magnetic support and a magnetic layer containing a ferromagnetic powder, The magnetic layer has a plurality of servo bands. The following five magnetic tape deformations: The deformation of magnetic tape after one year of storage in an environment with a temperature of 16°C and a relative humidity of 20%, The deformation of magnetic tape after one year of storage in an environment with a temperature of 16°C and a relative humidity of 80%, The deformation of magnetic tape after one year of storage in an environment with a temperature of 26°C and a relative humidity of 80%, The deformation of magnetic tape after one year of storage in an environment with a temperature of 32°C and a relative humidity of 20%, Deformation of magnetic tape after one year of storage in an environment with a temperature of 32°C and a relative humidity of 55%, The maximum deformation of the magnetic tape after storage for one year in the five environments is 0.50 μm or less. The rate of change in the amount of magnetic tape deformation relative to the change in relative humidity, calculated from the above five amounts of magnetic tape deformation, is 0.0001 μm / % or more and 0.0500 μm / % or less, and a magnetic tape cartridge in which the rate of change in the amount of magnetic tape deformation relative to a change in temperature, calculated from the above five amounts of magnetic tape deformation, is 0.0010 μm / °C or more and 0.1000 μm / °C or less; Regarding.

[0009] In one embodiment, the maximum deformation of the magnetic tape after one year of storage in five environments can be 0.01 μm or more and 0.50 μm or less.

[0010] In one embodiment, the magnetic tape can further include a non-magnetic layer containing non-magnetic powder between the non-magnetic support and the magnetic layer.

[0011] In one embodiment, the magnetic tape can further have a backcoat layer containing a nonmagnetic powder on the surface side of the nonmagnetic support opposite to the surface side having the magnetic layer.

[0012] In one embodiment, the non-magnetic support can be an aromatic polyester support.

[0013] In one form, the aromatic polyester support can be a polyethylene terephthalate support.

[0014] In one form, the aromatic polyester support can be a polyethylene naphthalate support.

[0015] In one form, the non-magnetic support can be an aromatic polyamide support.

[0016] In one embodiment, the squareness ratio of the magnetic tape in the perpendicular direction can be 0.60 or more.

[0017] One aspect of the present invention relates to a magnetic recording and reproducing device including the above magnetic tape cartridge.

[0018] In one embodiment, the magnetic recording and reproducing device can further include a magnetic head having a reproducing element width of 0.8 μm or less.

[0019] In one embodiment, the magnetic recording and reproducing device may include the magnetic tape cartridge and a take-up reel, and may run the magnetic tape between the take-up reel and the cartridge reel of the magnetic tape cartridge under tension in the longitudinal direction, the maximum value of this tension being 0.50 N (Newtons) or more, and the magnetic tape after running under the tension may be wound onto the cartridge reel of the magnetic tape cartridge under a tension of 0.40 N or less in the longitudinal direction. Effect of the Invention

[0020] According to one embodiment of the present invention, it is possible to perform data recording and / or playback on a magnetic tape after it has been stored in a magnetic tape cartridge, and by adjusting the tension applied in the longitudinal direction of the magnetic tape, the width direction dimension of the magnetic tape can be controlled to improve running stability during recording and / or playback. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram showing an example of a magnetic recording and reproducing device. [Diagram 2] 1 is a perspective view of an example of a magnetic tape cartridge. [Diagram 3] FIG. 2 is a perspective view showing when starting to wind the magnetic tape around the reel. [Figure 4] 2 is a perspective view of the state after the magnetic tape has been wound around the reel. FIG. [Diagram 5] 2 shows an example of the arrangement of data bands and servo bands. [Figure 6] An example of servo pattern arrangement on an LTO (Linear Tape-Open) Ultrium format tape is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] One aspect of the present invention relates to the above magnetic tape cartridge.

[0023] Another aspect of the present invention relates to a magnetic recording and reproducing device including the above magnetic tape cartridge.

[0024] The magnetic tape cartridge includes a magnetic tape and a cartridge reel. In an unused magnetic tape cartridge before being attached to a magnetic recording and / or reproducing device for recording and / or reproducing data, the magnetic tape is usually housed in a state wound on the cartridge reel. In the magnetic recording and reproducing device, the magnetic tape is run between a cartridge reel (supply reel) and a take-up reel to record data on the magnetic tape and / or reproduce the recorded data. After recording or reproducing data, the magnetic tape is rewound onto the cartridge reel and is stored in the magnetic tape cartridge in a state wound on the cartridge reel until the next recording and / or reproducing is performed. During storage, it is presumed that the magnetic tape housed in the magnetic tape cartridge undergoes deformation that differs depending on the position, with the portion close to the cartridge reel deforming wider than the initial width due to compressive stress in the tape thickness direction, and the portion farther from the cartridge reel deforming narrower than the initial width due to tensile stress in the tape longitudinal direction. If deformation that differs greatly depending on the position occurs, it is considered that this could cause the magnetic head to record and / or reproduce data while shifting from the target track position when recording and / or reproducing after storage. Through repeated studies, the inventors of the present invention have come to the conclusion that enabling data recording and / or reproduction to be performed satisfactorily on a magnetic tape after the magnetic tape has been housed in a magnetic tape cartridge and stored in various storage environments for at least one year would meet the needs of users expected in the future. In order to meet such needs, the inventors of the present invention have further conducted intensive studies in order to improve the running stability during recording and / or reproduction by controlling the widthwise dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape as described above. As a result, the inventors have come to the conclusion that the maximum deformation amount of the magnetic tape after one year of storage in five environments, the rate of change in the deformation amount of the magnetic tape relative to the change in relative humidity, and the rate of change in the deformation amount of the magnetic tape relative to the change in temperature should be controlled within the ranges described above.

[0025] The magnetic tape cartridge and magnetic recording / reproducing device will be described in more detail below. An embodiment of the magnetic tape cartridge and magnetic recording / reproducing device will be described below with reference to the drawings. However, the magnetic tape cartridge and magnetic recording / reproducing device are not limited to the embodiment shown in the drawings. Furthermore, the present invention is not limited by the inventor's speculations described in this specification.

[0026] [Maximum deformation of magnetic tape after one year storage in five environments] The method for measuring the maximum deformation of a magnetic tape after one year of storage in five environments is described below. The five environments are: "environment with temperature of 16°C and relative humidity of 20%", "environment with temperature of 16°C and relative humidity of 80%", "environment with temperature of 26°C and relative humidity of 80%", "environment with temperature of 32°C and relative humidity of 20%", and "environment with temperature of 32°C and relative humidity of 55%". The deformation of the magnetic tape after one year of storage in each environment was determined by the following method. First, before storing the magnetic tape in each of the five environments, the following measurements are taken regarding the dimensions of the magnetic tape before storage. The magnetic tape cartridge to be measured is placed in an environment with an ambient temperature of 23° C. and a relative humidity of 50% for five days in order to allow the magnetic tape to acclimate to the measurement environment. Then, in the measurement environment, the magnetic tape is run in a magnetic recording and reproducing device having a tension adjustment mechanism for applying tension in the longitudinal direction of the magnetic tape, with a tension of 0.70 N applied in the longitudinal direction of the magnetic tape. During this run, the interval between two adjacent servo bands sandwiching the data band is measured at 1 m intervals over the entire length of the magnetic tape. In various measurements described in this invention and this specification, the value of the tension applied in the longitudinal direction of the magnetic tape is a set value set in the magnetic recording and reproducing device. In this invention and this specification, "measured at 1 m intervals" means that, for a measurement target area of ​​length L meters (m), the position of one end of the measurement target area is 0 m, and the positions in the direction toward the other end are 1 m, 2 m, 3 m, and so on, and the position of the other end is Lm, the first measurement position is the position of 1 m, and the last measurement position is the position one position before the position of Lm. In addition, when there are multiple servo band intervals, the servo band intervals are measured for all servo band intervals in the same manner. The servo band interval thus measured is defined as the "servo band interval before storage" at each measurement position. The magnetic tape cartridge is then stored in one of the five environments for one year. A year for the storage period is 365 days. After such storage, the magnetic tape cartridge is placed in a measurement environment with an ambient temperature of 23°C and a relative humidity of 50% for 5 days, and then in the same measurement environment, the magnetic tape is run in a magnetic recording and reproducing device having a tension adjustment mechanism that applies tension in the longitudinal direction of the magnetic tape with a tension of 0.70 N applied to the magnetic tape in the longitudinal direction. During this run, the servo band interval is measured in the same manner as described above. The servo band interval measured in this manner is defined as the "servo band interval after storage" at each measurement position. For all servo band intervals, the difference between the servo band intervals measured at 1m intervals before storage and after storage is calculated. In this way, multiple difference values ​​are calculated. The maximum absolute value of the calculated differences is regarded as the magnetic tape deformation amount after one year of storage in each environment for the magnetic tape cartridge being measured. The interval between two adjacent servo bands sandwiching a data band can be calculated, for example, by using a PES (Position Error Signal) obtained from a servo signal obtained by reading a servo pattern using a servo signal reading element. For details, see the description of the embodiment described later. The magnetic tape cartridge to be measured is placed in one of the five environments listed above in sequence and stored for one year, after which the amount of magnetic tape deformation is measured using the method described above. The order in which the magnetic tape cartridge is stored in the five environments does not matter. Measurements are performed after storage in each environment in any sequence. The maximum value of the five values ​​of the amount of magnetic tape deformation thus obtained for the five environments is regarded as the maximum amount of magnetic tape deformation after one year of storage in the five environments. Note that the various measurement environments listed above are examples, and the magnetic tape cartridge is not limited to being stored and / or used in the environments listed as examples.

[0027] The maximum deformation amount of the magnetic tape after storage for one year in the five environments of the magnetic tape cartridge is 0.50 μm or less, preferably 0.40 μm or less, more preferably 0.30 μm or less, even more preferably 0.20 μm or less, and even more preferably 0.10 μm or less, from the viewpoint of enabling good recording and / or reproduction in the recording and / or reproduction of data on the magnetic tape after storage in the magnetic tape cartridge. The maximum deformation amount of the magnetic tape after storage in the five environments of the magnetic tape cartridge for one year can be, for example, 0.00 μm or more, more than 0.00 μm, 0.01 μm or more, 0.05 μm or more, or 0.10 μm or more. The smaller the value of the maximum deformation amount of the magnetic tape after storage in the five environments for one year, the more preferable it is from the viewpoint of enabling good recording and / or reproduction in the recording and / or reproduction of data on the magnetic tape after storage in the magnetic tape cartridge.

[0028] [Percentage of change in magnetic tape deformation with respect to change in relative humidity] The rate of change in magnetic tape deformation relative to change in relative humidity of the magnetic tape cartridge is the slope a obtained by the least squares method for the five magnetic tape deformation values ​​obtained for the five environments by the above method, where y is the magnetic tape deformation of the linear function y=ax+b (a is the slope and b is the intercept) and x is the relative humidity of the environment in which the magnetic tape deformation was obtained.

[0029] The rate of change in the amount of deformation of the magnetic tape relative to a change in the relative humidity of the magnetic tape cartridge is 0.0500 μm / % or less, preferably 0.0300 μm / % or less, and more preferably 0.0100 μm / % or less, from the viewpoint of enabling good recording and / or reproduction of data on the magnetic tape after it has been housed in the magnetic tape cartridge and stored. On the other hand, from the viewpoint of improving running stability (hereinafter also simply referred to as "running stability") when recording and / or reproduction is performed by controlling the width direction dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape, the rate of change in the amount of deformation of the magnetic tape relative to a change in the relative humidity of the magnetic tape cartridge is 0.0001 μm / % or more, preferably 0.0005 μm / % or more, more preferably 0.0010 μm / % or more, and even more preferably 0.0050 μm / % or more.

[0030] [Percentage of change in magnetic tape deformation relative to temperature change] For the above magnetic tape cartridge, the rate of change in magnetic tape deformation relative to change in temperature is the slope c obtained by the least squares method for the five magnetic tape deformation values ​​obtained for the five environments by the above method, where y is the magnetic tape deformation of the linear function y=cx+d (c is the slope and d is the intercept) and x is the temperature of the environment in which the magnetic tape deformation was obtained.

[0031] From the viewpoint of enabling good recording and / or reproduction of data on the magnetic tape after it has been housed in the magnetic tape cartridge and stored, the rate of change in the amount of deformation of the magnetic tape relative to the change in temperature of the magnetic tape cartridge is 0.1000 μm / ° C. or less, preferably 0.0700 μm / ° C. or less, and more preferably 0.0500 μm / ° C. or less. On the other hand, from the viewpoint of improving running stability, the rate of change in the amount of deformation of the magnetic tape relative to the change in temperature of the magnetic tape cartridge is 0.0010 μm / ° C. or more, preferably 0.0050 μm / ° C. or more, more preferably 0.0070 μm / ° C. or more, and even more preferably 0.0100 μm / ° C. or more.

[0032] The means for controlling the various values ​​mentioned above will be described later.

[0033] [Configuration of magnetic recording / reproducing device] FIG. 1 is a schematic diagram showing an example of a magnetic recording and reproducing device. A magnetic recording and reproducing device 10 shown in FIG. 1 controls a recording and reproducing head unit 12 in response to commands from a control device 11, and records and reproduces data on a magnetic tape MT. The magnetic recording and reproducing device 10 has a configuration capable of detecting and adjusting tension applied in the longitudinal direction of the magnetic tape from spindle motors 17A, 17B that control the rotation of cartridge reel 130 and take-up reel 16 and their drive devices 18A, 18B. The magnetic recording and reproducing device 10 has a configuration in which a magnetic tape cartridge 13 can be mounted. The magnetic recording and reproducing device 10 has a cartridge memory read / write device 14 capable of reading and writing data from and to a cartridge memory 131 in the magnetic tape cartridge 13 . From the magnetic tape cartridge 13 attached to the magnetic recording and playback device 10, the end or leader pin of the magnetic tape MT is pulled out by an automatic loading mechanism or manually, and the magnetic tape MT passes over the recording and playback head via guide rollers 15A and 15B with the magnetic layer surface in a direction facing the recording and playback head surface of the recording and playback head unit 12, and the magnetic tape MT is wound onto the take-up reel 16. The rotation and torque of spindle motors 17A and 17B are controlled by signals from control device 11, and magnetic tape MT runs at any speed and tension. A servo pattern formed in advance on the magnetic tape can be used to control the tape speed. A tension detection mechanism may be provided between magnetic tape cartridge 13 and take-up reel 16 to detect the tension. The tension may be adjusted using guide rollers 15A and 15B in addition to the control by spindle motors 17A and 17B. The cartridge memory read / write device 14 is configured to be able to read and write information from and to the cartridge memory 131 in response to commands from the control device 11. As a communication method between the cartridge memory read / write device 14 and the cartridge memory 131, for example, the ISO (International Organization for Standardization) 14443 method can be adopted.

[0034] The control device 11 includes, for example, a control unit, a storage unit, a communication unit, and the like.

[0035] The recording and reproducing head unit 12 is composed of, for example, a recording and reproducing head, a servo tracking actuator that adjusts the position of the recording and reproducing head in the track width direction, a recording and reproducing amplifier 19, a connector cable for connecting to the control device 11, etc. The recording and reproducing head is composed of, for example, a recording element that records data on the magnetic tape, a reproducing element that reproduces the data on the magnetic tape, and a servo signal reading element that reads the servo signal recorded on the magnetic tape. One magnetic head is equipped with, for example, one or more of each of the recording element, reproducing element, and servo signal reading element. Alternatively, each element may be provided separately in a plurality of magnetic heads according to the running direction of the magnetic tape.

[0036] The recording / reproducing head unit 12 is configured to be capable of recording data onto the magnetic tape MT in response to a command from the control device 11. Also, the recording / reproducing head unit 12 is configured to be capable of reproducing the data recorded onto the magnetic tape MT in response to a command from the control device 11.

[0037] The control device 11 has a mechanism for determining the running position of the magnetic tape from the servo signals read from the servo bands while the magnetic tape MT is running, and for controlling the servo tracking actuator so that the recording element and / or the reproducing element are positioned at the target running position (track position). The control of this track position is performed, for example, by feedback control. The control device 11 has a mechanism for determining the servo band interval from the servo signals read from two adjacent servo bands while the magnetic tape MT is running. The control device 11 also has a mechanism for adjusting and changing the tension applied in the longitudinal direction of the magnetic tape by controlling the torque of the spindle motor 17A and the spindle motor 17B and / or the guide rollers 15A and 15B so that the servo band interval becomes a target value. The adjustment of this tension is performed, for example, by feedback control. The control device 11 can also store information on the determined servo band interval in a storage unit inside the control device 11, a cartridge memory 131, an external connected device, or the like.

[0038] In the magnetic recording and reproducing device, tension can be applied in the longitudinal direction of the magnetic tape during recording and / or reproduction. In one embodiment, the tension applied in the longitudinal direction of the magnetic tape during recording and / or reproduction is a constant value, and in another embodiment, it varies. With respect to tension in the present invention and this specification, the value of the tension applied in the longitudinal direction of the magnetic tape in the magnetic recording and reproducing device is the value of tension used by the control device of the magnetic recording and reproducing device to control the mechanism for adjusting the above tension as the tension to be applied in the longitudinal direction of the magnetic tape. In addition, the tension actually applied in the longitudinal direction of the magnetic tape in the magnetic recording and reproducing device can be detected, for example, by providing a tension detection mechanism between the magnetic tape cartridge 13 and the take-up reel 16 in FIG. 1, as described above. Furthermore, for example, the minimum tension can be controlled by the control device of the magnetic recording and reproducing device so that it does not fall below a value or a recommended value set by a standard, etc., and / or the maximum tension does not exceed a value or a recommended value set by a standard, etc.

[0039] In one embodiment, the magnetic recording and reproducing device can have a tension adjustment mechanism capable of adjusting the tension applied in the longitudinal direction of the magnetic tape running in the magnetic recording and reproducing device. Such a tension adjustment mechanism can variably control the tension applied in the longitudinal direction of the magnetic tape, and preferably can control the dimension of the magnetic tape in the width direction by adjusting the tension applied in the longitudinal direction of the magnetic tape. In the above tension adjustment, the tension applied in the longitudinal direction of the magnetic tape can be changed. An example of a magnetic recording and reproducing device having a tension adjustment mechanism is as described above with reference to FIG. 1. However, the present invention is not limited to the example shown in FIG. 1.

[0040] [Magnetic tape cartridge] Before being loaded into a magnetic recording and reproducing device and after being removed from the magnetic recording and reproducing device, a magnetic tape cartridge generally contains a magnetic tape wound around a cartridge reel inside the cartridge body. The cartridge reel is rotatably provided inside the cartridge body. As magnetic tape cartridges, single-reel type magnetic tape cartridges having one reel inside the cartridge body and twin-reel type magnetic tape cartridges having two reels inside the cartridge body are widely used. The magnetic tape cartridge may be a single-reel type magnetic tape cartridge in one form, or a twin-reel type magnetic tape cartridge in another form. In the case of a twin-reel type magnetic tape cartridge, the cartridge reel refers to the reel on which the magnetic tape is mainly wound when it is stored after data is recorded and / or reproduced, and the other reel is referred to as the winding reel. When a single-reel type magnetic tape cartridge is loaded into a magnetic recording and reproducing device for recording and / or reproducing data on the magnetic tape, the magnetic tape is pulled out from the magnetic tape cartridge and wound around the take-up reel of the magnetic recording and reproducing device, as shown in FIG. 1 for example. A magnetic head is disposed on the magnetic tape transport path from the magnetic tape cartridge to the take-up reel. The magnetic tape runs by being fed out and taken up between the cartridge reel (also called the "supply reel") of the magnetic tape cartridge and the take-up reel of the magnetic recording and reproducing device. During this time, for example, the magnetic head and the magnetic layer surface of the magnetic tape come into contact with each other and slide, thereby recording and / or reproducing data. In contrast, a dual-reel type magnetic tape cartridge is provided with both a supply reel and a take-up reel inside the magnetic tape cartridge. In one embodiment, the magnetic tape cartridge is preferably a single-reel type magnetic tape cartridge that has been mainly adopted in the data storage field in recent years.

[0041] In one embodiment, the magnetic tape cartridge may include a cartridge memory. The cartridge memory may be, for example, a non-volatile memory, in which tension adjustment information is already recorded or tension adjustment information is to be recorded. The tension adjustment information is information for adjusting the tension applied in the longitudinal direction of the magnetic tape. For the cartridge memory, the above description may also be referred to.

[0042] Fig. 2 is a perspective view of an example of a magnetic tape cartridge, which is a single-reel type magnetic tape cartridge.

[0043] The magnetic tape cartridge 13 shown in Fig. 2 has a case 112. The case 112 is formed in a rectangular box shape. The case 112 is usually made of a resin such as polycarbonate. Only one reel 130 is rotatably housed inside the case 112.

[0044] Fig. 3 is a perspective view when winding of the magnetic tape onto the reel is started, and Fig. 4 is a perspective view when winding of the magnetic tape onto the reel is finished.

[0045] The reel 130 has a cylindrical reel hub 122 that forms the axial center portion.

[0046] The reel hub is a cylindrical member that constitutes the axial center portion around which the magnetic tape is wound within the magnetic tape cartridge. In the magnetic tape cartridge, the reel hub can be a cylindrical member having a single layer structure, or a cylindrical member having a multi-layer structure of two or more layers. From the viewpoint of manufacturing cost and ease of manufacturing, it is preferable that the reel hub be a cylindrical member having a single layer structure.

[0047] It is believed that the reel hub receives a winding force toward the center as the magnetic tape is wound, and tends to deform in a direction that reduces the diameter, and that the lower the rigidity of the reel hub, the easier it is to deform. It is believed that on the cartridge core side of the magnetic tape, compressive stress occurs in the direction that shortens the tape length in response to the deformation of the reel hub, and then tensile stress occurs in the direction that expands the tape width due to compression caused by this compressive stress. It is believed that the greater the stress thus generated, the more likely it is that the magnetic tape will deform significantly during storage in the magnetic tape cartridge. On the other hand, if the rigidity of the reel hub is high, it is possible to suppress the above-mentioned deformation, and therefore it is also possible to suppress the generation of the above-mentioned stress. It is believed that this can lead to smaller values ​​of the maximum deformation amount of the magnetic tape after one year of storage in five environments, the rate of change in the amount of deformation of the magnetic tape with respect to relative humidity, and the rate of change in the amount of deformation of the magnetic tape with respect to temperature. From this point of view, in one embodiment, the flexural modulus of the material constituting at least the outer peripheral surface layer portion of the reel hub is preferably 5 GPa or more, more preferably 6 GPa or more, even more preferably 7 GPa or more, and even more preferably 8 GPa or more. The flexural modulus may be, for example, 20 GPa or less, 15 GPa or less, or 10 GPa or less. However, since a high flexural modulus is preferable from the viewpoint of suppressing deformation of the reel hub, the flexural modulus may exceed the value exemplified here.

[0048] When the reel hub is a cylindrical member having a single layer structure, the above-mentioned flexural modulus is the flexural modulus of the material constituting the cylindrical member. On the other hand, when the reel hub is a cylindrical member having a multi-layer structure of two or more layers, the above-mentioned flexural modulus is the flexural modulus of the material constituting at least the outer peripheral surface layer of the reel hub. In the present invention and this specification, the "flexural modulus" is a value obtained according to JIS (Japanese Industrial Standards) K 7171:2016. JIS K 7171:2016 is a Japanese Industrial Standard created without changing the technical content based on ISO (International Organization for Standardization) 178 and Amendment 1:2013, which were published as the 5th edition in 2010. The test piece used to measure the flexural modulus is prepared according to item 6 "Test piece" of JIS K 7171:2016.

[0049] Examples of materials constituting the reel hub include resins and metals. Examples of metals include aluminum. From the viewpoints of cost and productivity, resins are preferred. Examples of resins include fiber-reinforced resins. Examples of fiber-reinforced resins include glass fiber-reinforced resins and carbon fiber-reinforced resins. As such fiber-reinforced resins, fiber-reinforced polycarbonate is preferred. This is because polycarbonate is easy to procure and can be molded with high precision and low cost using a general-purpose molding machine such as an injection molding machine. In addition, the glass fiber content in the glass fiber-reinforced resin is preferably 15% by mass or more. The higher the glass fiber content, the higher the bending modulus of the glass fiber-reinforced resin tends to be. As an example, the glass fiber content of the glass fiber-reinforced resin can be 50% by mass or less or 40% by mass or less. In one embodiment, the resin constituting the reel hub is preferably glass fiber-reinforced polycarbonate. In addition, examples of resins constituting the reel hub include high-strength resins generally called super engineering plastics. An example of a super engineering plastic is polyphenylene sulfide (PPS).

[0050] The thickness of the reel hub is preferably in the range of 2.0 to 3.0 mm from the viewpoint of achieving both the strength of the reel hub and the dimensional accuracy during molding. For a reel hub having a multi-layer structure of two or more layers, the thickness of the reel hub refers to the total thickness of the multi-layer structure. The outer diameter of the reel hub is usually determined by the standard of the magnetic recording and reproducing device, and can be in the range of 20 to 60 mm, for example.

[0051] At both ends of the reel hub 122, flanges (lower flange 124 and upper flange 126) are provided that extend radially outward from the lower end and upper end of the reel hub 122, respectively. Here, with regard to "upper" and "lower", the side located at the upper side when the magnetic tape cartridge is loaded into the magnetic recording and reproducing device is described as "upper" and the side located at the lower side is described as "lower". From the viewpoint of reinforcing the upper end side and / or the lower end side of the reel hub 122, it is preferable that one or both of the lower flange 124 and the upper flange 126 are integrally formed with the reel hub 122. "Integratedly formed" means that they are formed as one member, not as separate members. In the first embodiment, the reel hub 122 and the upper flange 126 are formed as one member, and this member is joined to the lower flange 124, which is formed as a separate member, by a known method. In the second embodiment, the reel hub 122 and the lower flange 124 are formed as one member, and this member is joined to the upper flange 126, which is formed as a separate member, by a known method. The reel of the magnetic tape cartridge may be in any form. Each member can be produced by a known molding method such as injection molding.

[0052] The magnetic tape MT is wound around the outer circumference of the reel hub 122, starting from the tape inner end Tf (see FIG. 3). Reducing the tension applied in the longitudinal direction of the magnetic tape when the magnetic tape is wound around the reel hub of the cartridge reel during manufacturing of the magnetic tape cartridge (hereinafter, also referred to as "manufacturing winding tension") can also lead to reducing the maximum deformation of the magnetic tape after one year of storage in five environments, the rate of change in the magnetic tape deformation with respect to the relative humidity, and the rate of change in the magnetic tape deformation with respect to the temperature. From this point of view, the manufacturing winding tension is preferably 0.40 N or less, and can be, for example, 0.30 N or less. The manufacturing winding tension can be, for example, 0.10 N or more or 0.20 N or more, or can be tension-free. The manufacturing winding tension can be a constant value or can be changed. The manufacturing winding tension is a set value set in the manufacturing device of the magnetic tape cartridge.

[0053] An opening 114 is formed in the side wall of the case 112 for pulling out the magnetic tape MT wound on the reel 130, and a leader pin 116 is fixed to the outer end Te of the magnetic tape MT pulled out from this opening 114, which is engaged and pulled out by a pull-out member (not shown) of a magnetic recording and reproducing device (not shown).

[0054] Furthermore, the opening 114 is adapted to be opened and closed by a door 118. The door 118 is formed in a rectangular plate shape large enough to close the opening 114, and is biased by a biasing member (not shown) in a direction to close the opening 114. When the magnetic tape cartridge 13 is loaded into the magnetic recording and reproducing device, the door 118 is adapted to be opened against the biasing force of the biasing member.

[0055] For other details of the magnetic tape cartridge, known techniques can be applied. The total length of the magnetic tape housed in the magnetic tape cartridge is not particularly limited, and can be, for example, in the range of about 800 m to 2500 m. The longer the total length of the tape housed in one magnetic tape cartridge, the more preferable it is from the viewpoint of increasing the capacity of the magnetic tape cartridge.

[0056] [Tension during running, tension during winding onto cartridge reel] In the magnetic recording and reproducing device, the magnetic tape is run between a cartridge reel (supply reel) and a take-up reel, and data can be recorded on the magnetic tape and / or the recorded data can be reproduced. In the magnetic recording and reproducing device, tension can be applied in the longitudinal direction of the magnetic tape during the running. The greater the tension applied in the longitudinal direction of the magnetic tape, the greater the shrinkage in the width direction of the magnetic tape (i.e., the narrower the width can be), and the smaller the tension, the smaller the degree of shrinkage can be. Therefore, the width direction dimension of the magnetic tape can be controlled by the value of the tension applied in the longitudinal direction of the magnetic tape running in the magnetic recording and reproducing device. In one embodiment of the magnetic recording and reproducing device, the magnetic tape can be run with a maximum tension of 0.50 N or more applied in the longitudinal direction. If the magnetic tape is stored in the magnetic tape cartridge after running with such a large tension applied, it is considered that the magnetic tape is likely to be deformed during storage. As described above, it is presumed that during storage, the magnetic tape contained in a magnetic tape cartridge undergoes deformation that varies depending on position, with the portion close to the cartridge reel deforming wider than initial due to compressive stress in the tape thickness direction, and the portion farther from the cartridge reel deforming narrower than initial due to tensile stress in the tape longitudinal direction, and that magnetic tape stored under large tension is more likely to experience greater differences in deformation depending on position. Therefore, in one embodiment, in the magnetic recording and reproducing device, when the magnetic tape is wound onto the cartridge reel after running with a tension of 0.50 N or more applied in the longitudinal direction, it is preferable that the tension applied in the longitudinal direction of the magnetic tape is 0.40 N or less. This makes it possible to wind the magnetic tape onto the cartridge reel with a tension smaller than the tension applied in the longitudinal direction during running and store it in the magnetic tape cartridge, and the inventor believes that the occurrence of the phenomenon that may occur due to the deformation described above can be further suppressed. Furthermore, the inventor presumes that, regardless of whether tension was applied during running or not and the value of the tension, it is preferable to apply a tension of 0.40 N or less in the longitudinal direction of the magnetic tape when winding the magnetic tape onto the cartridge reel after running in order to further suppress the occurrence of the phenomenon that may occur due to the deformation described above.

[0057] When tension is applied in the longitudinal direction of the magnetic tape in the above magnetic recording and reproducing device, the maximum value of the tension can be 0.50N or more, 0.60N or more, 0.70N or more, or 0.80N or more. The maximum value can be, for example, 1.50N or less, 1.40N or less, 1.30N or less, 1.20N or less, 1.10N or less, or 1.00N or less. The tension applied in the longitudinal direction of the magnetic tape during running can be a constant value or can be changed. In the case of a constant value, the tension applied in the longitudinal direction of the magnetic tape can be controlled, for example, by a control device of the magnetic recording and reproducing device, so that a constant value of tension is applied in the longitudinal direction of the magnetic tape. On the other hand, when the tension applied in the longitudinal direction of the magnetic tape during running is changed, for example, a servo signal can be used to obtain dimensional information in the width direction of the magnetic tape during running, and the tension applied in the longitudinal direction of the magnetic tape can be adjusted and changed according to the obtained dimensional information. This makes it possible to control the dimension in the width direction of the magnetic tape. One form of such tension adjustment has been described above with reference to FIG. 1. However, the magnetic recording and reproducing device is not limited to the embodiment shown in the example. In the magnetic recording and reproducing device, when the tension applied in the longitudinal direction of the running magnetic tape is changed, the minimum value can be, for example, 0.10 N or more, 0.20 N or more, 0.30 N or more, or 0.40 N or more. In one embodiment, the minimum value can be, for example, 0.40 N or less or less than 0.40 N, and in another embodiment, 0.60 N or less or 0.50 N or less.

[0058] In a magnetic recording and reproducing device, when a magnetic tape is run for recording and / or reproducing data, the following specific modes of running the magnetic tape can be given. Type 1: At the end of a run for recording and / or reproducing data, the entire length of the magnetic tape is wound onto the take-up reel. Type 2: At the end of a run for recording and / or reproducing data, the entire length of the magnetic tape is wound onto the cartridge reel. Mode 3: At the end of running for recording and / or reproducing data, a portion of the magnetic tape is wound on the cartridge reel and a portion is wound on the take-up reel.

[0059] The tension applied to the magnetic tape after it has been run in the longitudinal direction when it is wound onto the cartridge reel (hereinafter also referred to as "rewind tension") refers to the following tension. In the first embodiment, the rewinding tension is a tension applied in the longitudinal direction of the magnetic tape when the entire length of the magnetic tape is wound onto a cartridge reel to be housed in a magnetic tape cartridge. In form 2, first, the magnetic tape is wound from the cartridge reel onto the take-up reel. The tension applied to the magnetic tape in the longitudinal direction at this time is not particularly limited. It may be a constant value or may be variable, and may or may not follow the above description regarding the tension value during running. The tension applied to the magnetic tape in the longitudinal direction when it is subsequently wound onto the cartridge reel is the rewind tension. This tension is the tension applied to the magnetic tape in the longitudinal direction when the entire length of the magnetic tape is wound from the take-up reel onto the cartridge reel. Configuration 3 can be either of the following two configurations. In the first configuration (configuration 3-1), when the running for recording and / or reproducing data is completed, the portion of the magnetic tape wound around the cartridge reel is wound with tension in the longitudinal direction when it is wound around the cartridge reel. This tension during winding is the rewinding tension. In the second configuration (configuration 3-2), the configuration is a configuration other than configuration 3-1 of configuration 3. In configuration 3-1, in order to wind the entire length of the magnetic tape around the cartridge reel and accommodate it in the cartridge, the tension applied in the longitudinal direction of the magnetic tape when the magnetic tape that is not wound around the cartridge reel is wound around the cartridge reel is the rewinding tension. Configuration 3-2 is the same as configuration 2. That is, first, the magnetic tape is wound from the cartridge reel to the take-up reel. Then, the tension applied in the longitudinal direction of the magnetic tape when the entire length of the magnetic tape is wound from the take-up reel to the cartridge reel is the rewinding tension. In any of the above-mentioned forms 1, 2, and 3, the tension applied in the longitudinal direction of the magnetic tape when it is wound around the cartridge reel (rewinding tension) is preferably 0.40 N or less. The rewinding tension may be a constant value or may be changed. In one form, the rewinding tension may be a constant value of 0.40 N or less, or may be changed within a range of 0.40 N or less. When it is changed, the maximum value of the tension applied in the longitudinal direction of the magnetic tape when it is wound around the cartridge reel is preferably 0.40 N or less, and may be, for example, 0.30 N or less. The minimum value of the tension applied in the longitudinal direction of the magnetic tape when it is wound around the cartridge reel may be, for example, 0.10 N or more or 0.20 N or more, or may be less than the value exemplified here. The tension (rewinding tension) when it is wound around the cartridge reel can be controlled, for example, by a control device of the magnetic recording and reproducing device. In addition, an operating program may be recorded in the cartridge memory so that the magnetic tape is wound onto the cartridge reel with the set rewinding tension applied in the longitudinal direction after recording and / or playback of data on the magnetic tape, and the control device may read this program to perform the winding operation.

[0060] [Magnetic tape] In the magnetic tape cartridge, the magnetic tape is wound around a cartridge reel and housed therein. The magnetic tape will be described in more detail below.

[0061] <Nonmagnetic support> The magnetic tape has a non-magnetic support and a magnetic layer containing ferromagnetic powder. The non-magnetic support (hereinafter also simply referred to as "support") may be any of known biaxially oriented polyethylene terephthalate, polyethylene naphthalate, polyamide, polyamideimide, aromatic polyamide, and the like.

[0062] In one embodiment, the non-magnetic support of the magnetic tape may be an aromatic polyester support. In the present invention and this specification, "aromatic polyester" means a resin containing an aromatic skeleton and a plurality of ester bonds, and "aromatic polyester support" means a support containing at least one layer of aromatic polyester film. "Aromatic polyester film" means a film in which the component that constitutes this film in the largest proportion by mass is an aromatic polyester. In the present invention and this specification, the "aromatic polyester support" includes a support in which all the resin films contained in this support are aromatic polyester films, and a support containing an aromatic polyester film and another resin film. Specific embodiments of the aromatic polyester support include a single-layer aromatic polyester film, a laminated film of two or more layers of aromatic polyester films having the same constituent components, a laminated film of two or more layers of aromatic polyester films having different constituent components, a laminated film containing one or more layers of aromatic polyester films and one or more layers of resin films other than aromatic polyesters, and the like. In the laminated film, an adhesive layer or the like may be optionally included between two adjacent layers. In addition, the aromatic polyester support may optionally include a metal film and / or a metal oxide film formed by deposition or the like on one or both surfaces. The above also applies to the "polyethylene terephthalate support" and the "polyethylene naphthalate support" in the present invention and this specification.

[0063] The aromatic ring contained in the aromatic skeleton of the aromatic polyester is not particularly limited, but specific examples of the aromatic ring include a benzene ring and a naphthalene ring. For example, polyethylene terephthalate (PET) is a polyester containing a benzene ring, and is a resin obtained by polycondensation of ethylene glycol with terephthalic acid and / or dimethyl terephthalate. In the present invention and this specification, "polyethylene terephthalate" also includes structures having one or more other components (e.g., copolymerized components, components introduced into the terminals or side chains, etc.) in addition to the above components. Polyethylene naphthalate (PEN) is a polyester containing a naphthalene ring, and is a resin obtained by esterification of dimethyl 2,6-naphthalenedicarboxylate with ethylene glycol, followed by transesterification and polycondensation. In the present invention and this specification, "polyethylene naphthalate" also includes structures having one or more other components (e.g., copolymer components, components introduced into the terminals or side chains, etc.) in addition to the above components.

[0064] In one embodiment, the non-magnetic support of the magnetic tape can be an aromatic polyamide support. In the present invention and this specification, "aromatic polyamide" means a resin containing an aromatic skeleton and a plurality of amide bonds. The aromatic ring contained in the aromatic skeleton of the aromatic polyamide is not particularly limited. Specific examples of aromatic rings include, for example, a benzene ring. "Aromatic polyamide support" means a support containing at least one layer of aromatic polyamide film. "Aromatic polyamide film" means a film in which the component that is the most abundant component by mass among the components constituting this film is aromatic polyamide. The "aromatic polyamide support" in the present invention and this specification includes a support in which all the resin films contained in this support are aromatic polyamide films, and a support containing an aromatic polyamide film and another resin film. Specific embodiments of the aromatic polyamide support include a single layer aromatic polyamide film, a laminate film of two or more layers of aromatic polyamide films having the same constituent components, a laminate film of two or more layers of aromatic polyamide films having different constituent components, a laminate film containing one or more layers of aromatic polyamide films and one or more layers of resin films other than aromatic polyamide, and the like. The laminated film may optionally include an adhesive layer between two adjacent layers. The aromatic polyamide support may optionally include a metal film and / or a metal oxide film formed by deposition or the like on one or both surfaces.

[0065] The non-magnetic support may be a biaxially stretched film, and may be a film that has been subjected to corona discharge, plasma treatment, easy-adhesion treatment, heat treatment, or the like.

[0066] An example of an index of the physical properties of a non-magnetic support is the moisture content. In the present invention and this specification, the moisture content of a non-magnetic support is a value determined by the following method. The moisture contents shown in the table below are values ​​determined by the following method. A sample piece (e.g., a sample piece having a mass of several grams) cut out from the non-magnetic support for which moisture content is to be measured is dried until it reaches a constant weight in a vacuum dryer at a temperature of 180° C. and a pressure of 100 Pa (pascals) or less. The mass of the sample piece thus dried is designated as W1. W1 is a value measured in a measurement environment at a temperature of 23° C. and a relative humidity of 50% within 30 seconds after it is removed from the vacuum dryer. Next, W2 is the mass of the sample piece after it is placed in an environment at a temperature of 25° C. and a relative humidity of 75% for 48 hours. W2 is a value measured in a measurement environment at a temperature of 23° C. and a relative humidity of 50% within 30 seconds after it is removed from the environment. The moisture content is calculated by the following formula. Moisture content (%)=[(W2-W1) / W1]×100 For example, after removing the portions other than the non-magnetic support, such as the magnetic layer, from the magnetic tape by a known method (such as removal of the film using an organic solvent), the water content of the non-magnetic support can be determined by the above method.

[0067] In one embodiment, the non-magnetic support of the magnetic tape preferably has a moisture content of 2.0% or less, more preferably 1.8% or less, even more preferably 1.6% or less, even more preferably 1.4% or less, even more preferably 1.2% or less, and even more preferably 1.0% or less. The moisture content of the non-magnetic support of the magnetic tape may be 0%, 0% or more, more than 0%, or 0.1% or more. The use of a non-magnetic support with a low moisture content can lead to smaller values ​​of the maximum deformation of the magnetic tape after one year of storage in five environments, the rate of change in the deformation of the magnetic tape with respect to relative humidity, and the rate of change in the deformation of the magnetic tape with respect to temperature.

[0068] Young's modulus can also be mentioned as an index of the physical properties of a non-magnetic support. In the present invention and this specification, the Young's modulus of a non-magnetic support is a value measured by the following method in a measurement environment at a temperature of 23°C and a relative humidity of 50%. The Young's modulus shown in the table below is a value determined by the following method using a Tensilon manufactured by Toyo Baldwin Co., Ltd. as a universal tensile testing device. A sample piece cut out from the non-magnetic support to be measured is pulled by a universal tensile tester under the conditions of a chuck distance of 100 mm, a pulling speed of 10 mm / min, and a chart speed of 500 mm / min. As the universal tensile tester, for example, a commercially available universal tensile tester such as Toyo Baldwin's Tensilon or a universal tensile tester of a known configuration can be used. From the tangent of the rising part of the load-elongation curve thus obtained, the Young's modulus in the longitudinal direction and the width direction of the sample piece are calculated. Here, the longitudinal direction and the width direction of the sample piece refer to the longitudinal direction and the width direction when the sample piece is included in a magnetic tape. For example, after removing the portions other than the non-magnetic support, such as the magnetic layer, from the magnetic tape by a known method (e.g., removal using an organic solvent), the Young's modulus in the longitudinal and transverse directions of the non-magnetic support can be determined by the above method.

[0069] In one embodiment, the Young's modulus of the non-magnetic support of the magnetic tape in the longitudinal direction is preferably 3000 MPa or more, more preferably 4000 MPa or more, even more preferably 5000 MPa or more, and even more preferably 6000 MPa or more. The Young's modulus of the non-magnetic support of the magnetic tape in the longitudinal direction can be 15000 MPa or less, 13000 MPa or less, or 12000 MPa or less. In the width direction, the Young's modulus of the non-magnetic support of the magnetic tape in the width direction is preferably 2000 MPa or more, more preferably 3000 MPa or more, even more preferably 4000 MPa or more, and even more preferably 5000 MPa or more. The Young's modulus of the non-magnetic support of the magnetic tape in the width direction can be 12000 MPa or less, 11000 MPa or less, or 10000 MPa or less. When manufacturing a magnetic tape, the non-magnetic support is usually used with the MD direction (machine direction) of the film as the longitudinal direction and the TD direction (transverse direction) as the width direction. In one embodiment, the Young's modulus in the longitudinal direction is preferably greater than that in the transverse direction, and the difference (Young's modulus in the longitudinal direction - Young's modulus in the transverse direction) is more preferably in the range of 800 to 3000 MPa. The values ​​of the maximum deformation amount of the magnetic tape after storage for one year in the five environments, the rate of change in the deformation amount of the magnetic tape with respect to the relative humidity, and the rate of change in the deformation amount of the magnetic tape with respect to the temperature can also be controlled by the Young's modulus of the non-magnetic support.

[0070] The water content and Young's modulus of the nonmagnetic support can be controlled by the types and mixing ratios of the components constituting the support, the manufacturing conditions of the support, etc. For example, by adjusting the stretching ratio in each direction in the biaxial stretching process, the Young's modulus in the longitudinal direction and the Young's modulus in the transverse direction can be controlled, respectively.

[0071] <Magnetic layer> (Ferromagnetic powder) As the ferromagnetic powder contained in the magnetic layer of the magnetic tape, one or more of the ferromagnetic powders known as ferromagnetic powders used in the magnetic layers of various magnetic recording media can be used in combination. It is preferable to use a ferromagnetic powder with a small average particle size from the viewpoint of improving recording density. From this viewpoint, the average particle size of the ferromagnetic powder is preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less, even more preferably 35 nm or less, even more preferably 30 nm or less, even more preferably 25 nm or less, and even more preferably 20 nm or less. On the other hand, from the viewpoint of magnetization stability, the average particle size of the ferromagnetic powder is preferably 5 nm or more, more preferably 8 nm or more, even more preferably 10 nm or more, even more preferably 15 nm or more, and even more preferably 20 nm or more.

[0072] Hexagonal Ferrite Powder A preferred specific example of the ferromagnetic powder is hexagonal ferrite powder. For details of the hexagonal ferrite powder, see, for example, JP2011-225417A, paragraphs 0012-0030, JP2011-216149A, paragraphs 0134-0136, JP2012-204726A, paragraphs 0013-0030, and JP2015-127985A, paragraphs 0029-0084.

[0073] In the present invention and this specification, the term "hexagonal ferrite powder" refers to a ferromagnetic powder in which a hexagonal ferrite type crystal structure is detected as the main phase by X-ray diffraction analysis. The main phase refers to a structure to which the most intense diffraction peak belongs in the X-ray diffraction spectrum obtained by X-ray diffraction analysis. For example, when the most intense diffraction peak in the X-ray diffraction spectrum obtained by X-ray diffraction analysis is assigned to a hexagonal ferrite type crystal structure, it is determined that the hexagonal ferrite type crystal structure has been detected as the main phase. When only a single structure is detected by X-ray diffraction analysis, the detected structure is regarded as the main phase. The hexagonal ferrite type crystal structure contains at least an iron atom, a divalent metal atom, and an oxygen atom as constituent atoms. The divalent metal atom is a metal atom that can become a divalent cation as an ion, and examples of such include alkaline earth metal atoms such as strontium atoms, barium atoms, and calcium atoms, and lead atoms. In the present invention and this specification, the hexagonal strontium ferrite powder refers to a powder in which the main divalent metal atom contained therein is a strontium atom, and the hexagonal barium ferrite powder refers to a powder in which the main divalent metal atom contained therein is a barium atom. The main divalent metal atom refers to the divalent metal atom that is the most abundant of the divalent metal atoms contained in the powder on an atomic % basis. However, the above divalent metal atoms do not include rare earth atoms. In the present invention and this specification, the "rare earth atom" is selected from the group consisting of scandium atoms (Sc), yttrium atoms (Y), and lanthanoid atoms. The lanthanide atom is selected from the group consisting of a lanthanum atom (La), a cerium atom (Ce), a praseodymium atom (Pr), a neodymium atom (Nd), a promethium atom (Pm), a samarium atom (Sm), a europium atom (Eu), a gadolinium atom (Gd), a terbium atom (Tb), a dysprosium atom (Dy), a holmium atom (Ho), an erbium atom (Er), a thulium atom (Tm), a ytterbium atom (Yb), and a lutetium atom (Lu).

[0074] Hereinafter, hexagonal strontium ferrite powder, which is one form of hexagonal ferrite powder, will be described in more detail.

[0075] The activation volume of the hexagonal strontium ferrite powder is preferably 800 to 1600 nm 3 The finely divided hexagonal strontium ferrite powder exhibiting an activation volume in the above range is suitable for producing a magnetic tape exhibiting excellent electromagnetic conversion characteristics. The activation volume of the hexagonal strontium ferrite powder is preferably 800 nm 3 For example, 850 nm or more. 3 From the viewpoint of further improving the electromagnetic conversion characteristics, the activation volume of the hexagonal strontium ferrite powder can be 1500 nm or more. 3 More preferably, it is 1400 nm or less. 3 More preferably, it is 1300 nm or less. 3 More preferably, it is 1200 nm or less. 3 More preferably, it is equal to or less than 1100 nm. 3 It is even more preferable that the activation volume of the hexagonal barium ferrite powder is equal to or less than 1000 nm. The same is true for the activation volume of the hexagonal barium ferrite powder.

[0076] "Activation volume" is a unit of magnetization reversal and is an index showing the magnetic size of a particle. The activation volume and the anisotropy constant Ku described in the present invention and this specification are values ​​obtained by measuring the coercive force Hc measurement section at magnetic field sweep speeds of 3 minutes and 30 minutes (measurement temperature: 23°C ± 1°C) using a vibrating sample magnetometer, and calculating from the following relationship between Hc and activation volume V. The unit of the anisotropy constant Ku is 1 erg / cc = 1.0 x 10 -1 J / m 3 It is. Hc=2Ku / Ms{1-[(kT / KuV)ln(At / 0.693)] 1 / 2} [In the above formula, Ku: anisotropy constant (unit: J / m 3 ), Ms: saturation magnetization (unit: kA / m), k: Boltzmann constant, T: absolute temperature (unit: K), V: activation volume (unit: cm 3), A: spin precession frequency (unit: s -1 ), t: magnetic field reversal time (unit: s)]

[0077] The anisotropy constant Ku can be used as an index of reduction in thermal fluctuation, in other words, improvement in thermal stability. The hexagonal strontium ferrite powder is preferably 1.8×10 5 J / m 3 More preferably, the Ku is 2.0×10 or more. 5 J / m 3 The Ku of the hexagonal strontium ferrite powder can be, for example, 2.5×10 5 J / m 3 However, since a higher Ku value means higher thermal stability and is preferable, the Ku value is not limited to the above-mentioned values.

[0078] The hexagonal strontium ferrite powder may or may not contain rare earth atoms. When the hexagonal strontium ferrite powder contains rare earth atoms, it is preferable that the rare earth atoms are contained at a content (bulk content) of 0.5 to 5.0 atomic % relative to 100 atomic % of iron atoms. In one embodiment, the hexagonal strontium ferrite powder containing rare earth atoms can have uneven distribution of rare earth atoms in the surface layer portion. In the present invention and this specification, the term "surface distribution of rare earth atoms" refers to the rare earth atom content relative to 100 atomic % of iron atoms in a solution obtained by partially dissolving a hexagonal strontium ferrite powder in an acid (hereinafter referred to as "surface content of rare earth atoms" or simply "surface content" for rare earth atoms), which is greater than the rare earth atom content relative to 100 atomic % of iron atoms in a solution obtained by completely dissolving a hexagonal strontium ferrite powder in an acid (hereinafter referred to as "bulk content of rare earth atoms" or simply "bulk content" for rare earth atoms), Rare earth atom surface content / rare earth atom bulk content>1.0 The rare earth atom content of the hexagonal strontium ferrite powder described later is synonymous with the rare earth atom bulk content. In contrast, partial dissolution using an acid dissolves the surface layer of the particles constituting the hexagonal strontium ferrite powder, so the rare earth atom content in the solution obtained by partial dissolution is the rare earth atom content in the surface layer of the particles constituting the hexagonal strontium ferrite powder. The rare earth atom surface layer content satisfying the ratio of "rare earth atom surface layer content / rare earth atom bulk content>1.0" means that the rare earth atoms are unevenly distributed (i.e., more present in the surface layer) in the particles constituting the hexagonal strontium ferrite powder. In the present invention and this specification, the surface layer refers to a portion of the region extending from the surface of the particles constituting the hexagonal strontium ferrite powder toward the inside.

[0079] When the hexagonal strontium ferrite powder contains rare earth atoms, the rare earth atom content (bulk content) is preferably in the range of 0.5 to 5.0 atomic % relative to 100 atomic % of iron atoms. It is considered that the rare earth atoms contained in the bulk content in the above range and the rare earth atoms unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder contribute to suppressing the decrease in the reproduction output during repeated reproduction. This is presumed to be because the hexagonal strontium ferrite powder contains rare earth atoms in the bulk content in the above range and the rare earth atoms unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder can increase the anisotropy constant Ku. The higher the value of the anisotropy constant Ku, the more the occurrence of a phenomenon called thermal fluctuation can be suppressed (in other words, the thermal stability can be improved). By suppressing the occurrence of thermal fluctuation, the decrease in the reproduction output during repeated reproduction can be suppressed. It is speculated that the uneven distribution of rare earth atoms in the surface layer of hexagonal strontium ferrite powder particles contributes to stabilizing the spin of the iron (Fe) sites in the crystal lattice of the surface layer, thereby increasing the anisotropy constant Ku. In addition, it is presumed that using the hexagonal strontium ferrite powder having rare earth atom uneven distribution on the surface as the ferromagnetic powder of the magnetic layer also contributes to suppressing the wear of the magnetic layer surface due to sliding with the magnetic head. That is, it is presumed that the hexagonal strontium ferrite powder having rare earth atom uneven distribution on the surface can also contribute to improving the running durability of the magnetic tape. This is presumed to be because the uneven distribution of rare earth atoms on the surface of the particles constituting the hexagonal strontium ferrite powder contributes to improving the interaction between the particle surface and the organic substance (e.g., binder and / or additive) contained in the magnetic layer, and as a result, the strength of the magnetic layer is improved. From the viewpoint of further suppressing the decrease in regeneration output during repeated regeneration and / or further improving running durability, the rare earth atom content (bulk content) is more preferably in the range of 0.5 to 4.5 atomic %, even more preferably in the range of 1.0 to 4.5 atomic %, and even more preferably in the range of 1.5 to 4.5 atomic %.

[0080] The bulk content is the content obtained by completely dissolving the hexagonal strontium ferrite powder. In the present invention and this specification, unless otherwise specified, the content of an atom refers to the bulk content obtained by completely dissolving the hexagonal strontium ferrite powder. The hexagonal strontium ferrite powder containing rare earth atoms may contain only one rare earth atom as a rare earth atom, or may contain two or more rare earth atoms. When two or more rare earth atoms are contained, the bulk content is obtained for the total of two or more rare earth atoms. This point is the same for other components in the present invention and this specification. That is, unless otherwise specified, a certain component may be used in only one type, or in two or more types. When two or more types are used, the content or content refers to the total of two or more types.

[0081] When the hexagonal strontium ferrite powder contains rare earth atoms, the rare earth atoms contained therein may be any one or more of rare earth atoms. From the viewpoint of further suppressing the decrease in the reproduction output during repeated reproduction, preferred rare earth atoms include neodymium atoms, samarium atoms, yttrium atoms and dysprosium atoms, more preferred are neodymium atoms, samarium atoms and yttrium atoms, and even more preferred are neodymium atoms.

[0082] In the hexagonal strontium ferrite powder having rare earth atom uneven distribution in the surface layer, the rare earth atoms may be unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder, and the degree of uneven distribution is not limited. For example, for the hexagonal strontium ferrite powder having rare earth atom uneven distribution in the surface layer, the ratio of the surface content of rare earth atoms obtained by partial dissolution under the dissolution conditions described below to the bulk content of rare earth atoms obtained by complete dissolution under the dissolution conditions described below, "surface content / bulk content", is more than 1.0 and can be 1.5 or more. The "surface content / bulk content" being greater than 1.0 means that the rare earth atoms are unevenly distributed in the surface layer (i.e., more than in the interior) in the particles constituting the hexagonal strontium ferrite powder. In addition, the ratio of the surface layer content of rare earth atoms obtained by partial dissolution under the dissolution conditions described later to the bulk content of rare earth atoms obtained by total dissolution under the dissolution conditions described later, "surface layer content / bulk content", can be, for example, 10.0 or less, 9.0 or less, 8.0 or less, 7.0 or less, 6.0 or less, 5.0 or less, or 4.0 or less. However, in a hexagonal strontium ferrite powder having rare earth atom surface layer uneven distribution, it is sufficient that the rare earth atoms are unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder, and the above "surface layer content / bulk content" is not limited to the upper or lower limit exemplified.

[0083] The partial and total dissolution of hexagonal strontium ferrite powder will be described below. For hexagonal strontium ferrite powder present as powder, the sample powders to be partially and completely dissolved are taken from the same lot of powder. On the other hand, for hexagonal strontium ferrite powder contained in the magnetic layer of a magnetic tape, a part of the hexagonal strontium ferrite powder taken out from the magnetic layer is subjected to partial dissolution, and the other part is subjected to total dissolution. The hexagonal strontium ferrite powder can be taken out from the magnetic layer by, for example, the method described in paragraph 0032 of JP 2015-91747 A. The above-mentioned partial dissolution means that the hexagonal strontium ferrite powder is dissolved to such an extent that the remaining powder can be visually confirmed in the liquid at the end of dissolution. For example, the partial dissolution can dissolve a region of 10 to 20 mass% of the particles constituting the hexagonal strontium ferrite powder, with the whole particles being 100 mass%. On the other hand, the above-mentioned complete dissolution means that the hexagonal strontium ferrite powder is dissolved to such an extent that the remaining powder cannot be visually confirmed in the liquid at the end of dissolution. The partial dissolution and the surface layer content are measured, for example, by the following method. Note that the dissolution conditions such as the amount of sample powder are merely examples, and any dissolution conditions that allow partial or complete dissolution can be used. A container (e.g., a beaker) containing 12 mg of sample powder and 10 mL of 1 mol / L hydrochloric acid is placed on a hot plate set at 70°C for 1 hour. The resulting solution is filtered through a 0.1 μm membrane filter. Elemental analysis of the filtrate thus obtained is performed using an inductively coupled plasma (ICP) analyzer. In this way, the surface layer content of rare earth atoms relative to 100 atomic % of iron atoms can be determined. When multiple types of rare earth atoms are detected by elemental analysis, the total content of all rare earth atoms is taken as the surface layer content. This is also true for the measurement of bulk content. On the other hand, the total dissolved and bulk contents are measured, for example, by the following method. A container (e.g., a beaker) containing 12 mg of sample powder and 10 mL of 4 mol / L hydrochloric acid is placed on a hot plate set at 80° C. for 3 hours. After that, the bulk content relative to 100 atomic % of iron atoms can be calculated by carrying out the same procedure as the partial dissolution and surface layer content measurement described above.

[0084] From the viewpoint of increasing the reproduction output when reproducing data recorded on a magnetic tape, it is desirable for the mass magnetization σs of the ferromagnetic powder contained in the magnetic tape to be high. In this regard, hexagonal strontium ferrite powder that contains rare earth atoms but does not have uneven distribution of rare earth atoms in the surface layer has a tendency to have a significantly lower σs than hexagonal strontium ferrite powder that does not contain rare earth atoms. In contrast, hexagonal strontium ferrite powder that has uneven distribution of rare earth atoms in the surface layer is considered to be preferable in terms of suppressing such a large decrease in σs. In one embodiment, the σs of the hexagonal strontium ferrite powder is 45 A·m 2 / kg or more, and 47A·m 2 / kg or more. On the other hand, from the viewpoint of noise reduction, σs is 80A·m 2 / kg or less, and 60A·m 2 / kg or less. σs can be measured using a known measuring device capable of measuring magnetic properties, such as a vibrating sample magnetometer. In the present invention and this specification, unless otherwise specified, the mass magnetization σs is a value measured at a magnetic field strength of 15 kOe. 1 [kOe]=10 6 / 4π[A / m].

[0085] Regarding the content (bulk content) of the constituent atoms of the hexagonal strontium ferrite powder, the strontium atom content can be, for example, in the range of 2.0 to 15.0 atomic % relative to 100 atomic % of iron atoms. In one embodiment, the divalent metal atoms contained in the hexagonal strontium ferrite powder can be only strontium atoms. In another embodiment, the hexagonal strontium ferrite powder can also contain one or more other divalent metal atoms in addition to strontium atoms. For example, it can contain barium atoms and / or calcium atoms. When divalent metal atoms other than strontium atoms are contained, the barium atom content and calcium atom content in the hexagonal strontium ferrite powder can each be, for example, in the range of 0.05 to 5.0 atomic % relative to 100 atomic % of iron atoms.

[0086] Known crystal structures of hexagonal ferrite include magnetoplumbite type (also called "M type"), W type, Y type, and Z type. The hexagonal strontium ferrite powder may have any of the crystal structures. The crystal structure can be confirmed by X-ray diffraction analysis. The hexagonal strontium ferrite powder may be one in which a single crystal structure or two or more types of crystal structures are detected by X-ray diffraction analysis. For example, in one embodiment, the hexagonal strontium ferrite powder may be one in which only the M-type crystal structure is detected by X-ray diffraction analysis. For example, M-type hexagonal ferrite is AFe 12 O 19Here, A represents a divalent metal atom, and when the hexagonal strontium ferrite powder is of the M type, A is only a strontium atom (Sr), or when A contains a plurality of divalent metal atoms, the strontium atom (Sr) accounts for the largest proportion on an atomic % basis as described above. The divalent metal atom content of the hexagonal strontium ferrite powder is usually determined by the type of crystal structure of the hexagonal ferrite, and is not particularly limited. The same applies to the iron atom content and the oxygen atom content. The hexagonal strontium ferrite powder contains at least an iron atom, a strontium atom, and an oxygen atom, and may further contain a rare earth atom. Furthermore, the hexagonal strontium ferrite powder may or may not contain atoms other than these atoms. As an example, the hexagonal strontium ferrite powder may contain an aluminum atom (Al). The content of aluminum atoms can be, for example, 0.5 to 10.0 atomic % relative to 100 atomic % of iron atoms. From the viewpoint of further suppressing the decrease in the reproduction output during repeated reproduction, the hexagonal strontium ferrite powder contains iron atoms, strontium atoms, oxygen atoms, and rare earth atoms, and the content of atoms other than these atoms is preferably 10.0 atomic % or less, more preferably in the range of 0 to 5.0 atomic %, relative to 100 atomic % of iron atoms, and may be 0 atomic %. That is, in one embodiment, the hexagonal strontium ferrite powder may not contain atoms other than iron atoms, strontium atoms, oxygen atoms, and rare earth atoms. The content expressed in atomic % above is obtained by converting the content (unit: mass %) of each atom obtained by completely dissolving the hexagonal strontium ferrite powder into a value expressed in atomic % using the atomic weight of each atom. In addition, in the present invention and this specification, "not containing" a certain atom means that the content measured by an ICP analyzer after completely dissolving is 0 mass %. The detection limit of an ICP analyzer is usually 0.01 ppm (parts per million) or less on a mass basis. The above term "free" is used to mean that the content is below the detection limit of the ICP analyzer.In one form, the hexagonal strontium ferrite powder can be one that does not contain bismuth atoms (Bi).

[0087] metal powder A specific preferred example of the ferromagnetic powder is a ferromagnetic metal powder. For details of the ferromagnetic metal powder, reference can be made to, for example, paragraphs 0137 to 0141 of JP 2011-216149 A and paragraphs 0009 to 0023 of JP 2005-251351 A.

[0088] ε-iron oxide powder A preferred specific example of the ferromagnetic powder is ε-iron oxide powder. In the present invention and this specification, the term "ε-iron oxide powder" refers to a ferromagnetic powder in which the ε-iron oxide crystal structure is detected as the main phase by X-ray diffraction analysis. For example, when the highest intensity diffraction peak in the X-ray diffraction spectrum obtained by X-ray diffraction analysis is assigned to the ε-iron oxide crystal structure, it is determined that the ε-iron oxide crystal structure is detected as the main phase. Known methods for producing ε-iron oxide powder include a method of producing it from goethite and a reverse micelle method. All of the above production methods are publicly known. In addition, for a method for producing ε-iron oxide powder in which a part of Fe is replaced by a substitution atom such as Ga, Co, Ti, Al, or Rh, reference can be made to, for example, J. Jpn. Soc. Powder Metallurgy Vol. 61 Supplement, No. S1, pp. S280-S284, J. Mater. Chem. C, 2013, 1, pp.5200-5206, etc. However, the method for producing the ε-iron oxide powder that can be used as the ferromagnetic powder in the magnetic layer of the magnetic tape is not limited to the method given here.

[0089] The activation volume of the ε-iron oxide powder is preferably 300 to 1500 nm 3 The finely divided ε-iron oxide powder exhibiting an activation volume in the above range is suitable for producing a magnetic tape exhibiting excellent electromagnetic conversion characteristics. The activation volume of the ε-iron oxide powder is preferably 300 nm 3 For example, 500 nm or more.3 From the viewpoint of further improving the electromagnetic conversion characteristics, the activation volume of the ε-iron oxide powder can be 1400 nm or more. 3 More preferably, it is 1300 nm or less. 3 More preferably, it is 1200 nm or less. 3 More preferably, it is equal to or less than 1100 nm. 3 It is even more preferred that:

[0090] The anisotropy constant Ku can be used as an index of the reduction in thermal fluctuation, in other words, the improvement in thermal stability. The ε-iron oxide powder is preferably 3.0×10 4 J / m 3 More preferably, the Ku is 8.0×10 or more. 4 J / m 3 The Ku of the ε-iron oxide powder can be, for example, 3.0×10 5 J / m 3 However, since a higher Ku value means higher thermal stability and is preferable, the Ku value is not limited to the above-mentioned values.

[0091] From the viewpoint of increasing the reproduction output when reproducing data recorded on a magnetic tape, it is desirable that the mass magnetization σs of the ferromagnetic powder contained in the magnetic tape is high. In this regard, in one embodiment, the σs of the ε-iron oxide powder is 8 A m 2 / kg or more, and 12 A m 2 On the other hand, the σs of ε-iron oxide powder is 40 A m 2 / kg or less, and 35A·m 2 It is more preferable that the amount is not more than 1 / kg.

[0092] In the present invention and this specification, unless otherwise specified, the average particle size of various powders such as ferromagnetic powders is a value measured by the following method using a transmission electron microscope. The powder is photographed at a magnification of 100,000 times using a transmission electron microscope, and then printed on photographic paper at a total magnification of 500,000 times to obtain a photograph of the particles that make up the powder. From the obtained particle photograph, the target particle is selected, the particle's outline is traced with a digitizer, and the particle (primary particle) size is measured. Primary particles are independent particles that are not aggregated. The above measurements are carried out for 500 randomly selected particles. The arithmetic mean of the particle sizes of the 500 particles thus obtained is the average particle size of the powder. As the transmission electron microscope, for example, a Hitachi transmission electron microscope H-9000 type can be used. The particle size can be measured using known image analysis software, for example, Carl Zeiss image analysis software KS-400. The average particle size shown in the examples described below is a value measured using a Hitachi transmission electron microscope H-9000 type as the transmission electron microscope and Carl Zeiss image analysis software KS-400 as the image analysis software, unless otherwise specified. In the present invention and this specification, powder means a collection of multiple particles. For example, ferromagnetic powder means a collection of multiple ferromagnetic particles. In addition, the collection of multiple particles is not limited to a form in which the particles constituting the collection are in direct contact with each other, and also includes a form in which a binder, additive, etc., described later, are interposed between the particles. The term particle is sometimes used to refer to powder.

[0093] As a method for collecting sample powder from the magnetic tape for particle size measurement, for example, the method described in paragraph 0015 of JP 2011-048878 A can be used.

[0094] In the present invention and this specification, unless otherwise specified, the size of the particles constituting the powder (particle size) is determined by the shape of the particles observed in the particle photograph. (1) In the case of needle-shaped, spindle-shaped, columnar (where the height is greater than the maximum major axis of the base), etc., it is expressed by the length of the major axis that constitutes the particle, i.e., the major axis length. (2) In the case of a plate or columnar shape (where the thickness or height is smaller than the maximum long diameter of the plate or base), it shall be expressed by the maximum long diameter of the plate or base. (3) In the case of a particle having a spherical, polyhedral, or amorphous shape, and in which the major axis of the particle cannot be identified from its shape, the particle is expressed as the equivalent circle diameter, which is determined by the circle projection method.

[0095] The average acicular ratio of a powder refers to the arithmetic average of the short axis length of the particles, i.e., the short axis length, the (long axis length / short axis length) value of each particle, and the values ​​obtained for the 500 particles. Here, unless otherwise specified, the short axis length refers to the length of the short axis constituting the particle in the above definition of particle size (1), and to the thickness or height in the above definition of particle size (2), and in the above definition of particle size (3), since there is no distinction between the long axis and the short axis, (long axis length / short axis length) is considered to be 1 for the sake of convenience. Unless otherwise specified, when the particle shape is specific, for example, in the case of the above definition of particle size (1), the average particle size is the average major axis length, in the case of definition (2), the average particle size is the average plate diameter, and in the case of definition (3), the average particle size is the average diameter (also called the average particle diameter or average particle size).

[0096] The content (filling rate) of the ferromagnetic powder in the magnetic layer is preferably in the range of 50 to 90 mass % and more preferably in the range of 60 to 90 mass % relative to the total mass of the magnetic layer. A high filling rate of the ferromagnetic powder in the magnetic layer is preferable from the viewpoint of improving recording density.

[0097] (Binding Agent) The magnetic tape may be a coated magnetic tape, and may contain a binder in the magnetic layer. The binder is one or more kinds of resin. As the binder, various resins that are usually used as binders for coated magnetic tapes may be used. For example, as the binder, a resin selected from polyurethane resin, polyester resin, polyamide resin, vinyl chloride resin, acrylic resin copolymerized with styrene, acrylonitrile, methyl methacrylate, etc., cellulose resin such as nitrocellulose, epoxy resin, phenoxy resin, polyvinyl acetal, polyvinyl butyral, etc. may be used alone or in combination of a plurality of resins. Among these, polyurethane resin, acrylic resin, cellulose resin, and vinyl chloride resin are preferred. These resins may be homopolymers or copolymers. These resins may also be used as binders in the non-magnetic layer and / or backcoat layer described below. For the above binders, reference can be made to paragraphs 0028 to 0031 of JP 2010-24113 A. The average molecular weight of the resin used as the binder can be, for example, 10,000 to 200,000 in weight average molecular weight. The weight average molecular weight in the present invention and this specification is a value obtained by converting a value measured under the following measurement conditions by gel permeation chromatography (GPC) into polystyrene equivalent. The weight average molecular weight of the binder shown in the examples described later is a value obtained by converting a value measured under the following measurement conditions into polystyrene equivalent. The binder can be used in an amount of, for example, 1.0 to 30.0 parts by mass with respect to 100.0 parts by mass of the ferromagnetic powder. GPC equipment: HLC-8120 (Tosoh Corporation) Column: TSK gel Multipore HXL-M (Tosoh Corporation, 7.8 mm ID (inner diameter) × 30.0 cm) Eluent: tetrahydrofuran (THF)

[0098] (hardening agent) A curing agent can be used together with the resin usable as a binder. In one embodiment, the curing agent can be a thermosetting compound, which is a compound in which a curing reaction (crosslinking reaction) proceeds by heating, and in another embodiment, the curing agent can be a photocuring compound in which a curing reaction (crosslinking reaction) proceeds by light irradiation. As the curing reaction proceeds in the magnetic layer forming process, at least a part of the curing agent can be contained in the magnetic layer in a state of reacting (crosslinking) with other components such as the binder. This point is also true for layers formed using a composition used to form other layers that contains a curing agent. A preferred curing agent is a thermosetting compound, and polyisocyanate is suitable. For details on polyisocyanate, refer to paragraphs 0124 to 0125 of JP 2011-216149 A. The curing agent can be used in an amount of, for example, 0 to 80.0 parts by mass relative to 100.0 parts by mass of the binder, and preferably 50.0 to 80.0 parts by mass from the viewpoint of improving the strength of the magnetic layer.

[0099] (Additives) The magnetic layer may contain one or more additives as necessary. The additives may be selected from commercially available products according to the desired properties. Alternatively, compounds synthesized by known methods may be used as additives. The additives may be used in any amount. An example of the additive is the above-mentioned curing agent. Examples of additives contained in the magnetic layer include non-magnetic powders (e.g., inorganic powders, carbon black, etc.), lubricants, dispersants, dispersion aids, antifungal agents, antistatic agents, antioxidants, etc. For example, reference may be made to paragraphs 0030 to 0033, 0035, and 0036 of JP-A-2016-126817 for lubricants. The non-magnetic layer described below may contain a lubricant. Reference may be made to paragraphs 0030 to 0031, 0034, 0035, and 0036 of JP-A-2016-126817 for lubricants that may be contained in the non-magnetic layer. For the dispersant, refer to paragraphs 0061 and 0071 of JP-A-2012-133837. The dispersant may be added to the non-magnetic layer forming composition. For the dispersant that can be added to the non-magnetic layer forming composition, refer to paragraph 0061 of JP-A-2012-133837. In addition, examples of non-magnetic powders that can be included in the magnetic layer include non-magnetic powders that can function as abrasives, and non-magnetic powders (e.g., non-magnetic colloidal particles) that can function as protrusion-forming agents that form protrusions that protrude appropriately on the magnetic layer surface. For example, for the abrasives, refer to paragraphs 0030 to 0032 of JP-A-2004-273070. As the protrusion-forming agent, colloidal particles are preferred, and inorganic colloidal particles are preferred from the viewpoint of availability, inorganic oxide colloidal particles are more preferred, and silica colloidal particles (colloidal silica) are even more preferred. The average particle size of each of the abrasive and protrusion-forming agent is preferably in the range of 30 to 200 nm, and more preferably in the range of 50 to 100 nm.

[0100] The magnetic layer described above can be provided directly on the surface of the non-magnetic support, or indirectly via a non-magnetic layer.

[0101] <Nonmagnetic layer> Next, the non-magnetic layer will be described. The magnetic tape may have a magnetic layer directly on the surface of the non-magnetic support, or may have a magnetic layer on the surface of the non-magnetic support via a non-magnetic layer containing non-magnetic powder. The non-magnetic powder used in the non-magnetic layer may be an inorganic powder or an organic powder. Carbon black or the like may also be used. Examples of inorganic powder include powders of metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, metal sulfides, and the like. These non-magnetic powders are commercially available, and can also be produced by known methods. For details, refer to paragraphs 0146 to 0150 of JP-A-2011-216149. For carbon black usable in the non-magnetic layer, refer to paragraphs 0040 and 0041 of JP-A-2010-24113. The content (filling rate) of the non-magnetic powder in the non-magnetic layer is preferably in the range of 50 to 90% by mass, more preferably in the range of 60 to 90% by mass, based on the total mass of the non-magnetic layer.

[0102] The non-magnetic layer may contain a binder and may also contain an additive. For other details of the binder, additive, etc. of the non-magnetic layer, known techniques related to non-magnetic layers can be applied. In addition, for example, for the type and content of the binder, the type and content of the additive, known techniques related to magnetic layers can also be applied.

[0103] In the present invention and this specification, the nonmagnetic layer also includes a substantially nonmagnetic layer that contains a small amount of ferromagnetic powder, for example as an impurity or intentionally, together with the nonmagnetic powder. Here, the substantially nonmagnetic layer refers to a layer having a residual magnetic flux density of 10 mT or less, a coercive force of 7.96 kA / m (100 Oe) or less, or a layer having a residual magnetic flux density of 10 mT or less and a coercive force of 7.96 kA / m (100 Oe) or less. It is preferable that the nonmagnetic layer has no residual magnetic flux density or coercive force.

[0104] <Backcoat layer> The magnetic tape may or may not have a backcoat layer containing a nonmagnetic powder on the surface side opposite to the surface side having the magnetic layer of the nonmagnetic support. The backcoat layer preferably contains either one or both of carbon black and inorganic powder. The backcoat layer may contain a binder and may also contain additives. For the binder and additives of the backcoat layer, known techniques related to the backcoat layer may be applied, and known techniques related to the formulation of the magnetic layer and / or nonmagnetic layer may also be applied. For example, the descriptions of paragraphs 0018 to 0020 of JP 2006-331625 A and US Pat. No. 7,029,774, column 4, line 65 to column 5, line 38, may be referred to for the backcoat layer.

[0105] <Various thicknesses> Regarding the thickness (total thickness) of the magnetic tape, with the enormous increase in the amount of information in recent years, there is a demand for the magnetic tape to have an increased recording capacity (high capacity). One way to increase the capacity is to make the magnetic tape thinner (hereinafter also referred to as "thinner") and increase the length of the magnetic tape contained in one magnetic tape cartridge. From this point of view, the thickness (total thickness) of the magnetic tape is preferably 5.6 μm or less, more preferably 5.5 μm or less, more preferably 5.4 μm or less, and even more preferably 5.3 μm or less. From the viewpoint of ease of handling, the thickness of the magnetic tape is preferably 3.0 μm or more, and more preferably 3.5 μm or more.

[0106] The thickness (total thickness) of the magnetic tape can be measured by the following method. Ten tape samples (e.g., 5 to 10 cm long) are cut out from any part of the magnetic tape, and the tape samples are stacked and the thickness is measured. The measured thickness is divided by 10 to obtain the value (thickness per tape sample), which is the tape thickness. The thickness measurement can be performed using a known measuring device capable of measuring thickness to the order of 0.1 μm.

[0107] The thickness of the non-magnetic support is preferably 3.0 to 5.0 μm. The thickness of the magnetic layer can be optimized depending on the saturation magnetization amount of the magnetic head used, the head gap length, the band of the recording signal, etc., and is generally 0.01 μm to 0.15 μm, and from the viewpoint of high density recording, is preferably 0.02 μm to 0.12 μm, and more preferably 0.03 μm to 0.1 μm. At least one magnetic layer is sufficient, and the magnetic layer may be separated into two or more layers having different magnetic properties, and a known configuration related to a multilayer magnetic layer can be applied. When the magnetic layer is separated into two or more layers, the thickness of the magnetic layer is the total thickness of these layers. The thickness of the nonmagnetic layer is, for example, 0.1 to 1.5 μm, and preferably 0.1 to 1.0 μm. The thickness of the backcoat layer is preferably 0.9 μm or less, and more preferably 0.1 to 0.7 μm. Various thicknesses such as the thickness of the magnetic layer can be determined by the following method. A cross section of the magnetic tape in the thickness direction is exposed by an ion beam, and then the exposed cross section is observed by a scanning electron microscope. Various thicknesses can be obtained as the arithmetic average of thicknesses obtained at any two points in the cross section observation. Alternatively, various thicknesses can be obtained as design thicknesses calculated from manufacturing conditions, etc.

[0108] <Manufacturing process> (Preparation of compositions for forming each layer) The composition for forming the magnetic layer, non-magnetic layer or backcoat layer usually contains a solvent in addition to the various components described above. As the solvent, one or more of the various solvents usually used in the manufacture of coating-type magnetic recording media can be used. The solvent content of each layer-forming composition is not particularly limited. For the solvent, refer to paragraph 0153 of JP 2011-216149 A. The solid content concentration and solvent composition of each layer-forming composition may be appropriately adjusted according to the handling suitability of the composition, the coating conditions and the thickness of each layer to be formed. The process for preparing the composition for forming the magnetic layer, non-magnetic layer or backcoat layer usually includes at least a kneading process, a dispersing process, and a mixing process provided before or after these processes as necessary. Each individual process may be divided into two or more stages. The various components used in the preparation of each layer-forming composition may be added at the beginning or during any process. Also, each individual component may be added in two or more steps in a divided manner. For example, the binder may be added in a divided manner in the kneading process, the dispersing process and the mixing process for adjusting the viscosity after dispersion. In the manufacturing process of the magnetic tape, conventional known manufacturing techniques can be used as part of the process. In the kneading process, a device having a strong kneading force such as an open kneader, a continuous kneader, a pressure kneader, or an extruder can be used. Details of the kneading process are described in JP-A-1-106338 and JP-A-1-79274. As the dispersing machine, various known dispersing machines utilizing shear force such as a bead mill, a ball mill, a sand mill, or a homomixer can be used. Dispersing beads can be preferably used for dispersion. Examples of dispersing beads include ceramic beads and glass beads, and zirconia beads are preferred. Two or more types of beads may be used in combination. The bead diameter (particle size) and bead packing rate of the dispersing beads are not particularly limited and may be set according to the powder to be dispersed. Each layer-forming composition may be filtered by a known method before being subjected to the coating process. Filtration can be performed, for example, by filter filtration. As the filter used for filtration, for example, a filter with a pore size of 0.01 to 3 μm (for example, a glass fiber filter, a polypropylene filter, etc.) can be used.

[0109] (Coating process) The magnetic layer can be formed by directly applying the magnetic layer-forming composition onto the surface of the non-magnetic support, or by successively or simultaneously applying the magnetic layer-forming composition and the non-magnetic layer-forming composition in a multi-layer manner. The backcoat layer can be formed by applying the backcoat layer-forming composition onto the surface of the non-magnetic support opposite to the surface having the non-magnetic layer and / or magnetic layer (or the non-magnetic layer and / or magnetic layer will be provided later). For details of the coating for forming each layer, refer to paragraph 0066 of JP2010-231843A.

[0110] (Other processes) For other various steps for manufacturing the magnetic tape, known techniques can be applied. For various steps, for example, refer to paragraphs 0067 to 0070 of JP-A-2010-231843. For example, the coating layer of the magnetic layer-forming composition can be subjected to an orientation treatment in an orientation zone while the coating layer is in a wet state. For the orientation treatment, various known techniques including those described in paragraph 0052 of JP-A-2010-24113 can be applied. For example, the vertical orientation treatment can be performed by a known method such as a method using magnets with opposite poles facing each other. In the orientation zone, the drying speed of the coating layer can be controlled by the temperature and volume of the drying air and / or the transport speed in the orientation zone. In addition, the coating layer may be pre-dried before being transported to the orientation zone. As an example, the magnetic field strength in the vertical orientation treatment can be 0.1 to 1.5 T.

[0111] A long magnetic tape roll can be obtained by going through various processes. The obtained magnetic tape roll is cut (slit) by a known cutting machine to the width of the magnetic tape to be wound into a magnetic tape cartridge. The width is determined according to a standard, for example, 1 / 2 inch. 1 / 2 inch = 12.65 mm. A servo pattern is usually formed on the magnetic tape obtained by slitting. The formation of the servo pattern will be described in detail later.

[0112] (Heat treatment) In one embodiment, the magnetic tape can be a magnetic tape manufactured through the following heat treatment. In another embodiment, the magnetic tape can be a magnetic tape manufactured without the following heat treatment. The following heat treatment can lead to a reduction in the maximum deformation amount of the magnetic tape after one year of storage in five environments, the rate of change in the deformation amount of the magnetic tape with respect to the relative humidity, and the rate of change in the deformation amount of the magnetic tape with respect to the temperature.

[0113] As for the heat treatment, the magnetic tape may be slit and cut to a width determined according to a standard, wound around a core member, and the heat treatment may be performed in the wound state.

[0114] In one embodiment, the above-mentioned heat treatment is performed with the magnetic tape wound around a core-shaped member for heat treatment (hereinafter referred to as the "heat treatment core"), and the magnetic tape after heat treatment is wound onto a cartridge reel of a magnetic tape cartridge, thereby producing a magnetic tape cartridge in which the magnetic tape is wound around the cartridge reel. The heat treatment core may be made of metal, resin, paper, or the like. The material of the heat treatment core is preferably a material with high rigidity from the viewpoint of suppressing the occurrence of winding failures such as sporking. From this viewpoint, the heat treatment core is preferably made of metal or resin. In addition, as an index of rigidity, the bending elastic modulus of the material of the heat treatment core is preferably 0.2 GPa or more, more preferably 0.3 GPa or more. On the other hand, since high rigidity materials are generally expensive, using a heat treatment core made of a material having a rigidity exceeding the rigidity that can suppress the occurrence of winding failures leads to an increase in cost. In consideration of the above, the bending elastic modulus of the material of the heat treatment core is preferably 250 GPa or less. In addition, the heat treatment core may be a solid or hollow core-shaped member. In the case of a hollow shape, the wall thickness is preferably 2 mm or more from the viewpoint of maintaining rigidity. In addition, the heat treatment core may or may not have a flange. It is preferable to prepare a magnetic tape having a length equal to or greater than the length (hereinafter referred to as the "final product length") to be finally accommodated in a magnetic tape cartridge as the magnetic tape to be wound around the core for heat treatment, and to perform heat treatment by placing the magnetic tape wound around the core for heat treatment under a heat treatment environment. The length of the magnetic tape to be wound around the core for heat treatment is equal to or greater than the final product length, and from the viewpoint of ease of winding around the core for heat treatment, it is preferable that the length is "final product length + α". From the viewpoint of ease of winding, this α is preferably 5 m or more. The tension during winding around the core for heat treatment is preferably 0.10 N or more. In addition, from the viewpoint of suppressing excessive deformation during manufacturing, the tension during winding around the core for heat treatment is preferably 1.50 N or less, and more preferably 1.00 N or less. The outer diameter of the core for heat treatment is preferably 20 mm or more, and more preferably 40 mm or more, from the viewpoint of ease of winding and suppression of coiling (curl in the longitudinal direction). The outer diameter of the heat treatment core is preferably 100 mm or less, more preferably 90 mm or less. The width of the heat treatment core may be equal to or greater than the width of the magnetic tape wound around the core. After the heat treatment, when removing the magnetic tape from the heat treatment core, it is preferable to remove the magnetic tape from the heat treatment core after the magnetic tape and the heat treatment core have been sufficiently cooled in order to prevent unintended deformation of the tape during the removal operation. The removed magnetic tape is preferably once wound around another core (called a "temporary winding core"), and then the magnetic tape is preferably wound from the temporary winding core onto a cartridge reel of a magnetic tape cartridge (generally with an outer diameter of about 40 to 50 mm). This allows the magnetic tape to be wound around the cartridge reel of a magnetic tape cartridge while maintaining the relationship between the inside and outside of the magnetic tape with respect to the heat treatment core during the heat treatment. For details of the temporary winding core and the tension when winding the magnetic tape around this core, the above description of the heat treatment core can be referred to. In a form in which the above-mentioned heat treatment is performed on a magnetic tape having a length of "final product length + α", the length of "+ α" can be cut off at any stage. For example, in one form, the magnetic tape of the final product length is wound from a temporary winding core onto a reel of a magnetic tape cartridge, and the remaining length of "+ α" can be cut off.From the viewpoint of reducing the portion that is cut off and discarded, the above α is preferably 20 m or less.

[0115] A specific embodiment of the heat treatment performed in the state where the material is wound around the core member as described above will be described below. The atmospheric temperature at which the heat treatment is performed (hereinafter referred to as "heat treatment temperature") is preferably 40° C. or higher, and more preferably 50° C. or higher. On the other hand, from the viewpoint of suppressing excessive deformation, the heat treatment temperature is preferably 75° C. or lower, more preferably 70° C. or lower, and even more preferably 65° C. or lower. The weight absolute humidity of the atmosphere in which the heat treatment is carried out is preferably 0.1 g / kg dry air or more, more preferably 1 g / kg dry air or more. An atmosphere with a weight absolute humidity in the above range is preferable because it can be prepared without using a special device for reducing moisture. On the other hand, the weight absolute humidity is preferably 70 g / kg dry air or less, more preferably 66 g / kg dry air or less, from the viewpoint of suppressing the occurrence of condensation and the deterioration of workability. The heat treatment time is preferably 0.3 hours or more, more preferably 0.5 hours or more. Moreover, the heat treatment time is preferably 48 hours or less from the viewpoint of production efficiency.

[0116] (Formation of servo pattern) The magnetic tape has a plurality of servo bands in the magnetic layer. The servo bands are composed of servo patterns that are continuous in the longitudinal direction of the magnetic tape. The servo patterns on the magnetic tape enable tracking control of a magnetic head in a magnetic recording and reproducing device, control of the running speed of the magnetic tape, and the like. "Formation of a servo pattern" can also be called "recording of a servo signal." For example, the width direction dimension of the magnetic tape can be controlled by acquiring dimensional information of the magnetic tape in the width direction during the running using the servo signal, and adjusting and changing the tension applied to the magnetic tape in the longitudinal direction according to the acquired dimensional information.

[0117] The formation of the servo pattern will be described below.

[0118] The servo patterns are formed along the length of the magnetic tape. Control methods that use servo signals (servo control) include timing-based servo (TBS), amplitude servo, and frequency servo.

[0119] As shown in ECMA (European Computer Manufacturers Association)-319 (June 2001), magnetic tapes (generally called "LTO tapes") conforming to the LTO (Linear Tape-Open) standard employ a timing-based servo system. In this timing-based servo system, a servo pattern is formed by a pair of non-parallel magnetic stripes (also called "servo stripes") arranged continuously in the longitudinal direction of the magnetic tape. A servo system is a system that performs head tracking using a servo signal. In this invention and this specification, the "timing-based servo pattern" refers to a servo pattern that enables head tracking in a servo system of the timing-based servo system. As described above, the servo pattern is formed by a pair of non-parallel magnetic stripes in order to inform the servo signal reading element that passes over the servo pattern of its passing position. Specifically, the pair of magnetic stripes is formed so that the interval between them changes continuously along the width direction of the magnetic tape, and the servo signal reading element can know the relative position between the servo pattern and the servo signal reading element by reading the interval. This relative position information enables tracking of the data track. For this reason, a plurality of servo tracks are usually set on the servo pattern along the width direction of the magnetic tape.

[0120] A servo band is composed of a continuous servo pattern in the longitudinal direction of the magnetic tape. The magnetic tape has multiple servo bands in the magnetic layer. For example, there are five servo bands in an LTO tape. The area between two adjacent servo bands is the data band. The data band is composed of multiple data tracks, and each data track corresponds to one servo track.

[0121] Also, in one embodiment, as shown in JP 2004-318983 A, information indicating the number of the servo band (also called "servo band ID (identification)" or "UDIM (Unique Data Band Identification Method) information") is embedded in each servo band. This servo band ID is recorded by shifting a specific one of a plurality of pairs of servo stripes in the servo band so that its position is displaced relatively in the longitudinal direction of the magnetic tape. Specifically, the way in which a specific one of a plurality of pairs of servo stripes is shifted is changed for each servo band. As a result, the recorded servo band ID is unique for each servo band, so that the servo band can be uniquely identified simply by reading one servo band with a servo signal reading element.

[0122] As a method for uniquely identifying servo bands, there is also a method using the staggered method as shown in ECMA-319 (June 2001). In this staggered method, a group of pairs of non-parallel magnetic stripes (servo stripes) arranged continuously in the longitudinal direction of the magnetic tape are recorded so that they are shifted in the longitudinal direction of the magnetic tape for each servo band. The combination of the shift between adjacent servo bands is unique across the entire magnetic tape, so when the servo pattern is read by two servo signal reading elements, it is possible to uniquely identify the servo bands.

[0123] Also, as specified in ECMA-319 (June 2001), information indicating the longitudinal position of the magnetic tape (also called "LPOS (Longitudinal Position) information") is usually embedded in each servo band. Like UDIM information, this LPOS information is also recorded by shifting the positions of a pair of servo stripes in the longitudinal direction of the magnetic tape. However, unlike UDIM information, the same signal is recorded in each servo band with this LPOS information.

[0124] It is also possible to embed information other than the above UDIM information and LPOS information in the servo bands. In this case, the embedded information may be different for each servo band, such as UDIM information, or may be common to all servo bands, such as LPOS information. Also, methods other than those described above can be used to embed information in the servo bands. For example, a predetermined code may be recorded by thinning out a predetermined pair from a group of pairs of servo stripes.

[0125] The head for forming a servo pattern is called a servo write head. The servo write head usually has a pair of gaps corresponding to the pair of magnetic stripes, the number of which is equal to the number of servo bands. Usually, a core and a coil are connected to each pair of gaps, and a magnetic field generated in the core can generate a leakage magnetic field in the pair of gaps by supplying a current pulse to the coil. When forming a servo pattern, a magnetic pattern corresponding to the pair of gaps can be transferred to the magnetic tape by inputting a current pulse while running the magnetic tape on the servo write head, thereby forming the servo pattern. The width of each gap can be appropriately set according to the density of the servo pattern to be formed. The width of each gap can be set, for example, to 1 μm or less, 1 to 10 μm, or 10 μm or more.

[0126] Before forming a servo pattern on the magnetic tape, the magnetic tape is usually subjected to a demagnetization (erase) process. This erase process can be performed by applying a uniform magnetic field to the magnetic tape using a direct current magnet or an alternating current magnet. There are two types of erase processes: DC (Direct Current) erase and AC (Alternating Current) erase. AC erase is performed by gradually lowering the strength of the magnetic field applied to the magnetic tape while reversing the direction of the magnetic field. On the other hand, DC erase is performed by applying a unidirectional magnetic field to the magnetic tape. There are two more methods of DC erase. The first method is horizontal DC erase, which applies a unidirectional magnetic field along the longitudinal direction of the magnetic tape. The second method is vertical DC erase, which applies a unidirectional magnetic field along the thickness direction of the magnetic tape. The erase process may be performed on the entire magnetic tape, or may be performed for each servo band of the magnetic tape.

[0127] The direction of the magnetic field of the formed servo pattern is determined according to the direction of erasure. For example, when the magnetic tape is subjected to horizontal DC erasure, the servo pattern is formed so that the direction of the magnetic field is opposite to the direction of erasure. This makes it possible to increase the output of the servo signal obtained by reading the servo pattern. As shown in JP2012-53940A, when the magnetic pattern is transferred to the magnetic tape that has been vertically DC erased using the above gap, the servo signal obtained by reading the formed servo pattern has a unipolar pulse shape. On the other hand, when the magnetic pattern is transferred to the magnetic tape that has been horizontally DC erased using the above gap, the servo signal obtained by reading the formed servo pattern has a bipolar pulse shape.

[0128] Usually, after the servo pattern is formed, the magnetic tape is wound around a reel hub of a cartridge reel and housed in a magnetic tape cartridge.

[0129] <Vertical squareness ratio> In one embodiment, the perpendicular squareness of the magnetic tape can be, for example, 0.55 or more, and is preferably 0.60 or more. It is preferable that the perpendicular squareness of the magnetic tape is 0.60 or more from the viewpoint of improving electromagnetic conversion characteristics. The upper limit of the squareness is, in principle, 1.00 or less. The perpendicular squareness of the magnetic tape can be 1.00 or less, and can be 0.95 or less, 0.90 or less, 0.85 or less, or 0.80 or less. It is preferable that the perpendicular squareness of the magnetic tape has a large value from the viewpoint of improving electromagnetic conversion characteristics. The perpendicular squareness of the magnetic tape can be controlled by a known method such as performing a perpendicular orientation process.

[0130] In the present invention and this specification, the "perpendicular squareness" refers to the squareness measured in the perpendicular direction of the magnetic tape. The "perpendicular direction" described in relation to the squareness is the direction perpendicular to the magnetic layer surface, and can also be called the thickness direction. In the present invention and this specification, the perpendicular squareness is determined by the following method. A sample piece of a size that can be introduced into a vibration sample magnetometer is cut out from the magnetic tape to be measured. A magnetic field is applied to this sample piece in a vertical direction (perpendicular to the magnetic layer surface) using a vibration sample magnetometer at a maximum applied magnetic field of 3979 kA / m, a measurement temperature of 296 K, and a magnetic field sweep speed of 8.3 kA / m / sec, and the magnetization strength of the sample piece against the applied magnetic field is measured. The measured value of the magnetization strength is obtained as a value after demagnetization field correction and a value obtained by subtracting the magnetization of the sample probe of the vibration sample magnetometer as background noise. When the magnetization strength at the maximum applied magnetic field is Ms and the magnetization strength at zero applied magnetic field is Mr, the squareness ratio SQ is a value calculated as SQ=Mr / Ms. The measurement temperature refers to the temperature of the sample piece, and by setting the ambient temperature around the sample piece to the measurement temperature, the temperature equilibrium is established and the temperature of the sample piece can be set to the measurement temperature.

[0131] [Magnetic head] One aspect of the present invention relates to a magnetic recording and reproducing device including the magnetic tape cartridge. In the present invention and this specification, the term "magnetic recording and reproducing device" refers to a device capable of at least one of recording data to a magnetic tape and reproducing data recorded on the magnetic tape. Such a device is generally called a drive, and usually includes a magnetic head. A magnetic tape cartridge is inserted into the magnetic recording and reproducing device, and the magnetic tape is run in the magnetic recording and reproducing device, so that data can be recorded on the magnetic tape and / or the recorded data can be reproduced by the magnetic head. The magnetic head included in the magnetic recording and reproducing device can be a recording head capable of recording data on the magnetic tape, and can also be a reproducing head capable of reproducing data recorded on the magnetic tape. In one embodiment, the magnetic recording and reproducing device can include both a recording head and a reproducing head as separate magnetic heads. In another embodiment, the magnetic head included in the magnetic recording and reproducing device can have a configuration in which both a recording element and a reproducing element are provided in one magnetic head. As the reproducing head, a magnetic head (MR head) including a magnetoresistive (MR) element capable of reading information recorded on the magnetic tape with high sensitivity as a reproducing element is preferable. As the MR head, various known MR heads (for example, a GMR (Giant Magnetoresistive) head, a TMR (Tunnel Magnetoresistive) head, etc.) can be used. A servo pattern reading element may be included in the magnetic head that records and / or reproduces data. Alternatively, a magnetic head (servo head) equipped with a servo pattern reading element may be included in the magnetic recording and reproducing device as a head separate from the magnetic head that records and / or reproduces data. For example, a magnetic head that records and / or reproduces recorded data (hereinafter also referred to as a "recording and reproducing head") may include two servo signal reading elements, and each of the two servo signal reading elements can simultaneously read two adjacent servo bands sandwiching a data band. One or more data elements may be arranged between the two servo signal reading elements.The elements for recording data (recording elements) and the elements for reproducing data (reproducing elements) are collectively referred to as "data elements."

[0132] By using a reproducing element with a narrow reproducing element width as the reproducing element to reproduce data, data recorded at a high density can be reproduced with high sensitivity. From this viewpoint, the reproducing element width of the reproducing element is preferably 0.8 μm or less. The reproducing element width of the reproducing element can be, for example, 0.1 μm or more. However, from the above viewpoint, it is also preferable that the reproducing element width is less than this value. On the other hand, the narrower the reproducing element width, the more likely it is that phenomena such as reproduction failure due to off-track will occur. In order to suppress the occurrence of such phenomena, a magnetic recording and reproducing device is preferred that controls the dimension of the magnetic tape in the width direction by adjusting and changing the tension applied to the magnetic tape in the longitudinal direction while it is running. Here, the "reading element width" refers to the physical dimension of the reading element width. Such physical dimension can be measured using an optical microscope, a scanning electron microscope, or the like.

[0133] When recording data and / or reproducing recorded data, head tracking using servo signals can be performed first. That is, by making the servo signal reading element follow a specific servo track, the data element can be controlled to pass over the target data track. The data track is moved by changing the servo track read by the servo signal reading element in the tape width direction. The recording / reproducing head can also record and / or reproduce data on other data bands by using the UDIM information described above to move the servo signal reading element to a specific servo band and start tracking on that servo band.

[0134] FIG. 5 shows an example of the arrangement of data bands and servo bands. In FIG. 5, a plurality of servo bands 1 are arranged on the magnetic layer of the magnetic tape MT, sandwiched between guide bands 3. A plurality of regions 2 sandwiched between two servo bands are data bands. A servo pattern is a magnetized region, and is formed by magnetizing a specific region of the magnetic layer with a servo write head. The region magnetized by the servo write head (the position where the servo pattern is formed) is determined by a standard. For example, in an LTO Ultrium format tape, which is an industry standard, a plurality of servo patterns inclined with respect to the tape width direction are formed on the servo band during the manufacturing of the magnetic tape, as shown in FIG. 6. More specifically, in FIG. 6, a servo frame SF on the servo band 1 is composed of a servo subframe 1 (SSF1) and a servo subframe 2 (SSF2). The servo subframe 1 is composed of an A burst (symbol A in FIG. 6) and a B burst (symbol B in FIG. 6). The A burst is composed of servo patterns A1 to A5, and the B burst is composed of servo patterns B1 to B5. On the other hand, the servo subframe 2 is composed of a C burst (symbol C in FIG. 6) and a D burst (symbol D in FIG. 6). The C burst is composed of servo patterns C1 to C4, and the D burst is composed of servo patterns D1 to D4. Such 18 servo patterns are arranged in a subframe arranged in a 5, 5, 4, 4 arrangement in a set of 5 and 4, and are used to identify a servo frame. For the sake of explanation, one servo frame is shown in FIG. 6. However, in reality, a plurality of servo frames are arranged in the running direction in each servo band on the magnetic layer of a magnetic tape where head tracking of the timing-based servo method is performed. In FIG. 6, the arrow indicates the running direction. For example, an LTO Ultrium format tape usually has 5,000 or more servo frames per meter of tape length in each servo band on the magnetic layer. EXAMPLES

[0135] The present invention will be described below based on examples. However, the present invention is not limited to the embodiments shown in the examples. The indications of "parts" and "%" below mean "parts by mass" and "% by mass" unless otherwise specified. "eq" is an equivalent, and is a unit that cannot be converted to SI units. Moreover, the following various steps and operations were carried out in an environment with a temperature of 20 to 25° C. and a relative humidity of 40 to 60%, unless otherwise specified.

[0136] [Nonmagnetic support] In Table 1, "PEN" indicates a polyethylene naphthalate substrate, "PET" indicates a polyethylene terephthalate substrate, and "PA" indicates an aromatic polyamide substrate. The water content and Young's modulus in Table 1 are values ​​measured by the method described above.

[0137] [Ferromagnetic powder] In Table 1, "BaFe" in the ferromagnetic powder column indicates hexagonal barium ferrite powder with an average particle size (average plate diameter) of 21 nm.

[0138] In Table 1, "SrFe1" in the ferromagnetic powder column indicates hexagonal strontium ferrite powder prepared as follows. 1707 g of SrCO3, 687 g of H3BO3, 1120 g of Fe2O3, 45 g of Al(OH)3, 24 g of BaCO3, 13 g of CaCO3, and 235 g of Nd2O3 were weighed out and mixed in a mixer to obtain a raw material mixture. The obtained raw material mixture was melted in a platinum crucible at a melting temperature of 1390°C, and the melt was poured into a rod shape at about 6 g / sec by heating the tapping hole at the bottom of the platinum crucible while stirring the melt. The tapped liquid was rolled and quenched with a water-cooled twin roller to produce an amorphous body. 280 g of the produced amorphous body was placed in an electric furnace, heated to 635°C (crystallization temperature) at a heating rate of 3.5°C / min, and held at that temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles. Next, the crystallized material obtained above containing hexagonal strontium ferrite particles was coarsely crushed in a mortar, and 1000 g of zirconia beads with a particle size of 1 mm and 800 mL of 1% aqueous acetic acid solution were added to a glass bottle and dispersed for 3 hours using a paint shaker. The resulting dispersion was then separated from the beads and placed in a stainless steel beaker. The dispersion was left to stand at a liquid temperature of 100°C for 3 hours to dissolve the glass components, and then precipitated in a centrifuge and washed by repeated decantation, and dried for 6 hours in a heating furnace at a furnace temperature of 110°C to obtain hexagonal strontium ferrite powder. The average particle size of the hexagonal strontium ferrite powder obtained above is 18 nm, and the activation volume is 902 nm. 3 , the anisotropy constant Ku is 2.2×10 5 J / m 3 , mass magnetization σs is 49A m 2 / kg. A 12 mg sample powder was taken from the hexagonal strontium ferrite powder obtained above, and this sample powder was partially dissolved under the dissolution conditions exemplified above. The elemental analysis of the filtrate obtained was performed using an ICP analyzer to determine the surface layer content of neodymium atoms. Separately, 12 mg of sample powder was taken from the hexagonal strontium ferrite powder obtained above, and this sample powder was completely dissolved under the dissolution conditions exemplified above. The elemental analysis of the filtrate obtained was performed using an ICP analyzer to determine the bulk content of neodymium atoms. The neodymium atom content (bulk content) relative to 100 atomic % of iron atoms in the hexagonal strontium ferrite powder obtained above was 2.9 atomic %. The surface layer content of neodymium atoms was 8.0 atomic %. The ratio of the surface layer content to the bulk content, "surface layer content / bulk content," was 2.8, confirming that neodymium atoms were unevenly distributed in the surface layers of the particles.

[0139] It was confirmed that the powder obtained above exhibited a hexagonal ferrite crystal structure by scanning with CuKα radiation at a voltage of 45 kV and an intensity of 40 mA and measuring the X-ray diffraction pattern under the following conditions (X-ray diffraction analysis). The powder obtained above exhibited a magnetoplumbite-type (M-type) hexagonal ferrite crystal structure. The crystal phase detected by the X-ray diffraction analysis was a single phase of magnetoplumbite type. PANalytical X'Pert Pro diffractometer, PIXcel detector Soller slits for incident and diffracted beams: 0.017 radians Dispersion slit fixed angle: 1 / 4 degree Mask: 10mm Anti-scatter slit: 1 / 4 degree Measurement mode: Continuous Measurement time per step: 3 seconds Measurement speed: 0.017 degrees per second Measurement step: 0.05 degrees

[0140] In Table 1, "SrFe2" in the ferromagnetic powder column indicates hexagonal strontium ferrite powder prepared as follows. 1725 g of SrCO3, 666 g of H3BO3, 1332 g of Fe2O3, 52 g of Al(OH)3, 34 g of CaCO3, and 141 g of BaCO3 were weighed out and mixed in a mixer to obtain a raw material mixture. The obtained raw material mixture was melted in a platinum crucible at a melting temperature of 1380°C, and the melt was poured into a rod shape at about 6 g / sec by heating the tapping hole at the bottom of the platinum crucible while stirring the melt. The tapped liquid was rolled and quenched with a water-cooled twin roll to produce an amorphous body. 280 g of the obtained amorphous body was placed in an electric furnace, heated to 645° C. (crystallization temperature), and held at that temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles. Next, the crystallized material obtained above containing hexagonal strontium ferrite particles was coarsely crushed in a mortar, and 1000 g of zirconia beads with a particle size of 1 mm and 800 mL of 1% aqueous acetic acid solution were added to a glass bottle and dispersed for 3 hours using a paint shaker. The resulting dispersion was then separated from the beads and placed in a stainless steel beaker. The dispersion was left to stand at a liquid temperature of 100°C for 3 hours to dissolve the glass components, and then precipitated in a centrifuge and washed by repeated decantation, and dried for 6 hours in a heating furnace at a furnace temperature of 110°C to obtain hexagonal strontium ferrite powder. The average particle size of the obtained hexagonal strontium ferrite powder was 19 nm, and the activation volume was 1102 nm. 3 , the anisotropy constant Ku is 2.0×10 5 J / m 3 , mass magnetization σs is 50A m 2 / kg.

[0141] In Table 1, "ε-iron oxide" in the ferromagnetic powder column indicates ε-iron oxide powder prepared as follows. 8.3g of iron (III) nitrate nonahydrate, 1.3g of gallium (III) nitrate octahydrate, 190mg of cobalt (II) nitrate hexahydrate, 150mg of titanium (IV) sulfate, and 1.5g of polyvinylpyrrolidone (PVP) were dissolved in 90g of pure water, and 4.0g of ammonia solution with a concentration of 25% was added under the condition of an atmospheric temperature of 25°C while stirring with a magnetic stirrer in the air, and the mixture was stirred for 2 hours at an atmospheric temperature of 25°C. A citric acid solution obtained by dissolving 1g of citric acid in 9g of pure water was added to the obtained solution, and the mixture was stirred for 1 hour. The powder precipitated after stirring was collected by centrifugation, washed with pure water, and dried in a heating furnace at an internal temperature of 80°C. 800g of pure water was added to the dried powder, and the powder was dispersed in water again to obtain a dispersion. The obtained dispersion was heated to 50°C, and 40g of 25% ammonia aqueous solution was added dropwise while stirring. After stirring for 1 hour while maintaining the temperature at 50°C, 14mL of tetraethoxysilane (TEOS) was added dropwise and stirred for 24 hours. 50g of ammonium sulfate was added to the obtained reaction solution, and the precipitated powder was collected by centrifugation, washed with pure water, and dried for 24 hours in a heating furnace with an internal temperature of 80°C to obtain a precursor of ferromagnetic powder. The obtained precursor of the ferromagnetic powder was placed in a heating furnace at an internal temperature of 1000° C. in an air atmosphere and subjected to a heat treatment for 4 hours. The heat-treated ferromagnetic powder precursor was placed in a 4 mol / L aqueous solution of sodium hydroxide (NaOH), and the liquid temperature was maintained at 70°C while stirring for 24 hours, thereby removing impurities such as silicate compounds from the heat-treated ferromagnetic powder precursor. Thereafter, the silicic acid compound was removed by centrifugation, and the ferromagnetic powder was collected and washed with pure water to obtain a ferromagnetic powder. The composition of the obtained ferromagnetic powder was confirmed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The results showed that the powder was composed of Ga, Co, and Ti substituted ε-iron oxide (ε-Ga 0.28 Co 0.05 Ti 0.05 Fe 1.62 In addition, X-ray diffraction analysis was performed under the same conditions as those described above for the hexagonal strontium ferrite powder SrFe1, and it was confirmed from the peaks in the X-ray diffraction pattern that the obtained ferromagnetic powder had a single-phase ε-phase crystal structure (ε-iron oxide crystal structure) that did not contain α- or γ-phase crystal structures. The average particle size of the obtained ε-iron oxide powder was 12 nm, and the activation volume was 746 nm. 3 , the anisotropy constant Ku is 1.2×10 5 J / m 3 , mass magnetization σs is 16A m 2 / kg.

[0142] The activation volume and anisotropy constant Ku of the above hexagonal strontium ferrite powder and ε-iron oxide powder were determined for each ferromagnetic powder by the method described above using a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd.). The mass magnetization σs is a value measured using a vibrating sample magnetometer (manufactured by Toei Industry Co., Ltd.) at a magnetic field strength of 1194 kA / m (15 kOe).

[0143] [Example 1] (1) Preparation of alumina dispersion Alpha conversion rate approximately 65%, BET (Brunauer-Emmett-Teller) specific surface area 20m 2 100.0 parts of alumina powder (HIT-80 manufactured by Sumitomo Chemical Co., Ltd.) with a molecular weight of 100 g / g was mixed with 3.0 parts of 2,3-dihydroxynaphthalene (manufactured by Tokyo Chemical Industry Co., Ltd.), 31.3 parts of a 32% solution (solvent is a mixed solvent of methyl ethyl ketone and toluene) of polyester polyurethane resin having SO3Na groups as polar groups (UR-4800 manufactured by Toyobo Co., Ltd. (polar group amount: 80 meq / kg)), and 570.0 parts of a mixed solution of methyl ethyl ketone and cyclohexanone 1:1 (mass ratio) as a solvent, and dispersed for 5 hours using a paint shaker in the presence of zirconia beads. After dispersion, the dispersion liquid and the beads were separated using a mesh to obtain an alumina dispersion.

[0144] (2) Magnetic layer forming composition formulation (Magnetic liquid) Ferromagnetic powder (see Table 1) 100.0 parts SO3Na group-containing polyurethane resin 14.0 parts Weight average molecular weight: 70,000, SO3Na group: 0.2meq / g Cyclohexanone 150.0 parts Methyl ethyl ketone 150.0 parts (abrasive liquid) 6.0 parts of the alumina dispersion prepared in (1) above (Silica sol (protrusion forming liquid)) Colloidal silica (average particle size 120 nm) 2.0 parts Methyl ethyl ketone 1.4 parts (Other Ingredients) Stearic acid 2.0 parts Stearic acid amide 0.2 parts Butyl stearate 2.0 parts Polyisocyanate (Tosoh Corporation, Coronate (registered trademark) L) 2.5 parts (Finishing solvent) Cyclohexanone 200.0 parts Methyl ethyl ketone 200.0 parts

[0145] (3) Formulation of composition for forming nonmagnetic layer Non-magnetic inorganic powder: α-iron oxide 100.0 parts Average particle size (average major axis length): 0.15μm Average acicular ratio: 7 BET specific surface area: 52m 2 / g Carbon black 20.0 parts Average particle size: 20nm SO3Na group-containing polyurethane resin 18.0 parts Weight average molecular weight: 70,000, SO3Na group: 0.2meq / g Stearic acid 2.0 parts Stearic acid amide 0.2 parts Butyl stearate 2.0 parts Cyclohexanone 300.0 parts Methyl ethyl ketone 300.0 parts

[0146] (4) Formulation of composition for forming backcoat layer Carbon black 100.0 parts DBP (Dibutyl phthalate) oil absorption 74cm 3 / 100g Nitrocellulose 27.0 parts Polyester polyurethane resin containing sulfonic acid groups and / or their salts 62.0 copies Polyester resin 4.0 parts Alumina powder (BET specific surface area: 17m 2 / g) 0.6 parts Methyl ethyl ketone 600.0 parts Toluene 600.0 parts Polyisocyanate (Tosoh Corporation, Coronate (registered trademark) L) 15.0 parts

[0147] (5) Preparation of compositions for forming each layer The magnetic layer forming composition was prepared by the following method. The magnetic liquid was prepared by dispersing each component for 24 hours (bead dispersion) using a batch-type vertical sand mill. Zirconia beads with a bead diameter of 0.5 mm were used as the dispersion beads. The prepared magnetic liquid, the abrasive liquid, and other components (silica sol, other components, and finishing additive solvent) were mixed using the sand mill and dispersed with beads for 5 minutes, and then treated with a batch-type ultrasonic device (20 kHz, 300 W) for 0.5 minutes (ultrasonic dispersion). After that, filtration was performed using a filter with a pore size of 0.5 μm to prepare the magnetic layer forming composition. The composition for forming the nonmagnetic layer was prepared by the following method. The above components, except for the lubricants (stearic acid, stearic acid amide, and butyl stearate), were kneaded and diluted using an open kneader, and then dispersed using a horizontal bead mill disperser. The lubricants (stearic acid, stearic acid amide, and butyl stearate) were then added, and the mixture was stirred and mixed using a dissolver stirrer to prepare the composition for forming the nonmagnetic layer. The composition for forming a backcoat layer was prepared by the following method. The above components except for the polyisocyanate were introduced into a dissolver mixer, stirred at a peripheral speed of 10 m / sec for 30 minutes, and then dispersed using a horizontal bead mill disperser. Then, the polyisocyanate was added, and the mixture was stirred and mixed using the dissolver mixer to prepare the composition for forming a backcoat layer.

[0148] (6) Methods for manufacturing magnetic tapes and magnetic tape cartridges The nonmagnetic layer-forming composition prepared in (5) above was applied and dried on the surface of the support described in Table 1, which was biaxially stretched to a thickness of 4.0 μm, so that the thickness after drying was 1.0 μm, to form a nonmagnetic layer. Next, the magnetic layer-forming composition prepared in (5) above was applied on the nonmagnetic layer so that the thickness after drying was 0.1 μm, to form a coating layer. Thereafter, while the coating layer of the magnetic layer-forming composition was still in a wet state, a magnetic field with a magnetic field strength of 0.3 T was applied in the perpendicular direction to the surface of the coating layer to perform a vertical orientation treatment, and then the coating layer was dried to form a magnetic layer. Thereafter, the backcoat layer-forming composition prepared in (5) above was applied and dried on the surface of the support opposite to the surface on which the nonmagnetic layer and magnetic layer were formed, so that the thickness after drying was 0.5 μm, to form a backcoat layer. Thereafter, a surface smoothing treatment (calendering) was performed using a calender roll consisting only of a metal roll at a speed of 100 m / min, a linear pressure of 300 kg / cm, and a calender temperature of 90° C. (surface temperature of the calender roll). Thereafter, the long magnetic tape was heat-treated by storing it in a heat treatment furnace at an atmospheric temperature of 70°C (heat treatment time: 36 hours). After the heat treatment, the magnetic tape was slit into 1 / 2 inch width to obtain a magnetic tape. A servo signal was recorded on the magnetic layer of the obtained magnetic tape by a commercially available servo writer to obtain a magnetic tape having a data band, a servo band, and a guide band in an arrangement according to the LTO (Linear Tape-Open) Ultrium format, and having a servo pattern (timing-based servo pattern) on the servo band with an arrangement and shape according to the LTO Ultrium format. The servo pattern thus formed is a servo pattern according to the descriptions of JIS (Japanese Industrial Standards) X6175:2006 and Standard ECMA-319 (June 2001). The total number of servo bands is 5, and the total number of data bands is 4. The magnetic tape (length 970 m) after the servo pattern was formed was wound around a core for heat treatment, and heat treatment was performed while the tape was wound around the core. A solid core-shaped member (outer diameter: 50 mm) made of resin with a flexural modulus of elasticity of 0.8 GPa was used as the core for heat treatment, and the tension during winding was 0.60 N. The heat treatment was performed for 5 hours at the heat treatment temperature shown in Table 1. The weight absolute humidity of the atmosphere in which the heat treatment was performed was 10 g / kg dry air. After the above heat treatment, the magnetic tape and the heat treatment core were sufficiently cooled, and then the magnetic tape was removed from the heat treatment core and wound onto a temporary winding core, and then the magnetic tape of the final product length (960 m) was wound from the temporary winding core onto the reel hub of the reel of the magnetic tape cartridge in the longitudinal direction with tension of the value listed in the "Winding tension at manufacturing" column in Table 1, and the remaining 10 m was cut off, and a leader tape was joined to the end of the cut side using a commercially available splicing tape in accordance with item 9 of Standard ECMA (European Computer Manufacturers Association)-319 (June 2001) Section 3. A solid core-shaped member made of the same material and having the same outer diameter as the heat treatment core was used as the temporary winding core. As the magnetic tape cartridge for accommodating the magnetic tape, a single-reel type magnetic tape cartridge having the configuration shown in FIG. 2 was used. The reel hub of this magnetic tape cartridge is a single-layer reel hub (thickness: 2.5 mm, outer diameter: 44 mm) made by injection molding glass fiber reinforced polycarbonate. The glass fiber content of this glass fiber reinforced polycarbonate is the value shown in Table 1 (unit: mass %). A part of the glass fiber reinforced polycarbonate for injection molding was taken, and a recommended test piece described in JIS K 7171:2016, item 6.3.1 (production from molding material) was prepared according to the same JIS, item 6.1.2. The bending modulus (arithmetic average of five test pieces) was obtained according to the same JIS, and the value was shown in Table 1. For the examples and comparative examples described later, the bending modulus of the reel hub material was obtained by the above method. The bending modulus of the above-mentioned heat treatment winding core was also obtained in the same manner. As a result of the above, a single-reel type magnetic tape cartridge of Example 1 was produced, in which a magnetic tape of 960 m in length was wound around a reel.

[0149] [Examples 2 to 26, Comparative Examples 1 to 11] A magnetic tape cartridge was prepared in the same manner as described in Example 1, except that the items in Table 1 were changed as shown in Table 1. In the comparative examples in Table 1 where the "Heat treatment temperature" column is marked "None," no heat treatment was performed while the magnetic tape was wound around the heat treatment core, and the magnetic tape having a final product length of 960 m was housed in a magnetic tape cartridge.

[0150] For each of the above examples and comparative examples, three magnetic tape cartridges were produced, one was used to evaluate the magnetic tape deformation amount and tape thickness described below, another was used to evaluate the recording and playback performance described below, and the remaining one was used to evaluate the running stability described below.

[0151] [Evaluation method] <Maximum deformation of magnetic tape after one year storage in five environments> The magnetic tape cartridge to be measured was placed in a measurement environment of 23° C. and 50% relative humidity for 5 days to allow it to acclimate to the measurement environment. Thereafter, under the above measurement environment, the magnetic tape was run in the magnetic recording and reproducing device shown in Figure 1 with a tension of 0.70 N applied in the longitudinal direction of the magnetic tape. During this run, the distance between two adjacent servo bands sandwiching the data band was measured at 1 m intervals over the entire length of the magnetic tape. Measurements were performed for all servo band distances. The servo band distances measured in this way were designated as the "servo band distance before storage" at each measurement position. The distance between two adjacent servo bands sandwiching the data band was determined as follows. To determine the distance between two adjacent servo bands with a data band in between, the dimensions of the servo pattern are required. The standards for the dimensions of the servo pattern differ depending on the generation of LTO. First, we use a magnetic force microscope or similar to measure the average distance AC between the four corresponding stripes of the A burst and the C burst, and the azimuth angle α of the servo pattern. Next, the servo patterns formed on the magnetic tape are read sequentially along the tape longitudinal direction using a reel tester and a servo head equipped with two servo signal reading elements (hereinafter, one is called the upper side and the other is called the lower side) fixed at an interval in a direction perpendicular to the longitudinal direction of the magnetic tape. The average time between five stripes corresponding to A burst and B burst over the length of one LPOS word is defined as a. The average time between four stripes corresponding to A burst and C burst over a length of 1 m is defined as b. In this case, the value defined as AC×(1 / 2-a / b) / (2×tan(α)) represents the read position PES in the width direction based on the servo signal obtained by the servo signal reading element. The servo patterns are read simultaneously by two servo signal reading elements on the upper and lower sides. The value of PES obtained by the upper servo signal reading element is defined as PES1, and the value of PES obtained by the lower servo signal reading element is defined as PES2. The interval between two adjacent servo bands sandwiching a data band can be obtained as "PES2-PES1". This is because the upper and lower servo pattern reading elements are fixed to the servo head and the distance between them does not change. Thereafter, the magnetic tape cartridge was stored for one year in five environments, namely, "environment of temperature 16°C and relative humidity 20%", "environment of temperature 16°C and relative humidity 80%", "environment of temperature 26°C and relative humidity 80%", "environment of temperature 32°C and relative humidity 20%", and "environment of temperature 32°C and relative humidity 55%", by the method described above, and the servo band intervals after one year of storage were measured. Storage in the five environments was performed in the order of "environment of temperature 16°C and relative humidity 20%" → "environment of temperature 16°C and relative humidity 80%" → "environment of temperature 26°C and relative humidity 80%" → "environment of temperature 32°C and relative humidity 20%" → "environment of temperature 32°C and relative humidity 55%". However, the order is not limited to this. From the servo band intervals obtained after one year of storage in each environment, the magnetic tape deformation amount after one year of storage in each environment was obtained by the method described above. The maximum value of the five magnetic tape deformation amounts obtained for the five environments was taken as the maximum magnetic tape deformation amount after one year of storage in the five environments.

[0152] <Percentage of change in magnetic tape deformation with respect to change in relative humidity> For the five magnetic tape deformation values ​​obtained after one year of storage in each of the five environments mentioned above, the magnetic tape deformation was expressed as y in the linear function y=ax+b (a is the slope and b is the intercept), the relative humidity of the environment in which the magnetic tape deformation was obtained was expressed as x, and the slope a obtained by the least squares method was calculated as the ratio of the change in magnetic tape deformation to the change in relative humidity.

[0153] <Proportion of change in magnetic tape deformation with respect to temperature change> For the five magnetic tape deformation values ​​obtained after one year of storage in each of the five environments mentioned above, the magnetic tape deformation was expressed as y in the linear function y=cx+d (c is the slope and d is the intercept), and the temperature of the environment in which the magnetic tape deformation was obtained was expressed as x. The slope c obtained by the least squares method was calculated as the ratio of the change in magnetic tape deformation to the change in temperature.

[0154] <Tape thickness> After the above evaluation, the magnetic tape cartridge was placed in an environment with a temperature of 20 to 25°C and a relative humidity of 40 to 60% for 5 days or more to allow it to acclimate to the environment. Then, still in the same environment, 10 tape samples (5 cm long) were cut out from any part of the magnetic tape removed from the magnetic tape cartridge, and these tape samples were stacked and the thickness was measured. The thickness was measured using a digital thickness meter with a Millimar 1240 compact amplifier and a Millimar 1301 inductive probe manufactured by MARH. The measured thickness was divided by 10 to obtain the value (thickness per tape sample), which was taken as the tape thickness. The tape thickness for each magnetic tape was 5.6 μm.

[0155] <Evaluation of recording / playback performance> (1) Recording of data on magnetic tape before storage and playback of recorded data Recording and playback before storage were performed using a magnetic recording and playback device with the configuration shown in Figure 1. The recording and playback head mounted on the recording and playback head unit has 32 or more channels of playback elements (playback element width: 0.8 μm) and recording elements, with servo signal reading and playback elements on both sides. For each magnetic tape cartridge, the environment in which recording and playback, which will be described later, were performed was the environment in which the amount of magnetic tape deformation was the maximum among the five environments mentioned above. In order to acclimate the magnetic tape cartridge to the recording environment, it was placed in the playback environment for five days. After that, recording was performed in the same environment as follows. A magnetic tape cartridge is set in a magnetic recording and playback device, and the magnetic tape is loaded. Next, while performing servo tracking, the recording and playback head unit records pseudo-random data with a specific data pattern onto the magnetic tape. A constant tension of 0.50 N is applied to the tape in the longitudinal direction during this process. At the same time as the data is recorded, the servo band intervals along the entire length of the tape are measured every 1 m along the length, and recorded in the cartridge memory. Next, the data recorded on the magnetic tape is reproduced by the recording / reproducing head unit while performing servo tracking. At this time, the value of the servo band interval is measured simultaneously with the reproduction, and the tension applied in the longitudinal direction of the tape is changed so that the absolute value of the difference from the servo band interval at the time of recording at the same longitudinal position approaches 0 based on the information recorded in the cartridge memory. During reproduction, the measurement of the servo band interval and the tension control based on the measurement are performed continuously in real time. During such reproduction, the tension applied in the longitudinal direction of the magnetic tape is changed in the range of 0.50N to 0.85N by the control device of the magnetic recording / reproducing device. Therefore, during the above reproduction, the maximum value of the tension applied in the longitudinal direction of the magnetic tape is 0.85N. At the end of the playback, the entire length of the magnetic tape has been wound onto the cartridge reel of the magnetic tape cartridge.

[0156] (2) Winding (rewinding) onto a cartridge reel and storing Subsequently, in the same environment, the magnetic tape was run in the magnetic recording and reproducing device and the entire length of the magnetic tape was wound onto the take-up reel of the magnetic recording and reproducing device. During this winding, the tension applied to the magnetic tape in the longitudinal direction was set to a constant value of 0.40 N. Thereafter, a constant tension of 0.40 N was applied to the magnetic tape in the longitudinal direction, and the entire length of the magnetic tape was wound onto the cartridge reel (also referred to as "rewinding"). After the above-mentioned rewinding, the magnetic tape cartridge containing the magnetic tape was stored for one year in each of the following environments: "environment of 16°C and 20% relative humidity" → "environment of 16°C and 80% relative humidity" → "environment of 26°C and 80% relative humidity" → "environment of 32°C and 20% relative humidity" → "environment of 32°C and 55% relative humidity."

[0157] (3) Evaluation of recording and playback performance after storage After the above storage, in order to acclimate the magnetic tape cartridge to the environment in which it would be played back, the magnetic tape cartridge was placed in the environment in which the magnetic tape deformation was greatest among the above five environments for five days. Thereafter, playback was performed in the same environment in the same manner as in the playback before storage in (1) above. That is, playback was performed while changing the tension applied to the magnetic tape in the longitudinal direction as described above. The number of channels in the above playback was 32. When playback after storage was performed, if the data of all 32 channels was read correctly, the recording and playback performance was evaluated as "4." If the data of 31 or 30 channels was read correctly, the recording and playback performance was evaluated as "3." If the data of 29 or 28 channels was read correctly, the recording and playback performance was evaluated as "2." In all other cases, the recording and playback performance was evaluated as "1."

[0158] <Evaluation of driving stability> Using each of the magnetic tape cartridges of the examples and comparative examples, data was recorded and reproduced using a magnetic recording and reproducing device having the configuration shown in Fig. 1. The recording and reproducing head mounted on the recording and reproducing head unit has 32 or more channels of reproducing elements (reproducing element width: 0.8 μm) and recording elements, and has servo signal reading elements on both sides. Data was recorded and reproduced by the following method, and the running stability during reproduction was evaluated. A magnetic tape cartridge is set in a magnetic recording and playback device, and the magnetic tape is loaded. Next, while performing servo tracking, the recording and playback head unit records pseudo-random data with a specific data pattern onto the magnetic tape. A constant tension is applied to the tape in the longitudinal direction during this process. At the same time as the data is recorded, the servo band intervals along the entire length of the tape are measured every 1m along the longitudinal direction, and are recorded in the cartridge memory. Next, the data recorded on the magnetic tape is played back by the recording / playback head unit while performing servo tracking. At the same time as playback, the servo band interval is measured, and based on the information recorded in the cartridge memory, the tension applied in the longitudinal direction of the tape is controlled so that the absolute value of the difference from the servo band interval at the time of recording at the same longitudinal position approaches zero. During playback, the servo band interval is measured and tension is controlled based on the measurement in real time continuously. The running stability was evaluated using as an index the standard deviation (hereinafter referred to as "σPES") of the read position PES (Position Error Signal) in the width direction based on the servo signal obtained by the servo signal reading element during the above reproduction. PES is calculated in the following manner: To calculate the PES, the dimensions of the servo pattern are required. The standard dimensions of the servo pattern differ depending on the generation of LTO. First, we use a magnetic force microscope or similar to measure the average distance AC between the four corresponding stripes of the A burst and the C burst, and the azimuth angle α of the servo pattern. The average time between five stripes corresponding to A burst and B burst over the length of one LPOS word is defined as a. The average time between four stripes corresponding to A burst and C burst over the length of one LPOS word is defined as b. In this case, the value defined by AC×(1 / 2-a / b) / (2×tan(α)) is the read position PES (Position Error Signal) in the width direction based on the servo signal obtained by the servo signal reading element over the length of one LPOS word. For the magnetic tape, the end wound on the reel of the magnetic tape cartridge is called the inner end, and the opposite end is called the outer end. The outer end is set to 0 m, and the standard deviation (σPES) of the PES obtained by the above method was calculated for a region in the tape longitudinal direction over a length of 30 m to 200 m. If σPES is less than 70 nm, it can be determined that the running stability is excellent.

[0159] The above results are shown in Table 1 (Table 1-1 to Table 1-3).

[0160] [Table 1-1]

[0161] [Table 1-2]

[0162] [Table 1-3]

[0163] For the magnetic tape cartridge of Example 1, the recording and reproducing performance was evaluated using the above method, except that the rewinding tension for winding the cartridge reel was changed from 0.40 N to 0.50 N, and the evaluation result was "2."

[0164] A magnetic tape cartridge was produced in the same manner as described above for Example 1, except that no vertical orientation treatment was performed during the production of the magnetic tape. A sample piece was cut out from the magnetic tape removed from the magnetic tape cartridge. The squareness in the vertical direction of the sample piece was measured by the above-mentioned method using a vibrating sample magnetometer, TM-TRVSM5050-SMSL model manufactured by Tamagawa Seisakusho, and was found to be 0.55. The magnetic tape was also removed from the magnetic tape cartridge of Example 1, and a sample piece was cut out from this magnetic tape. The squareness ratio in the vertical direction was similarly determined to be 0.60.

[0165] The magnetic tapes taken out of the two magnetic tape cartridges were each attached to a 1 / 2 inch reel tester, and the electromagnetic conversion characteristics (SNR; Signal-to-Noise Ratio) were evaluated by the following method. As a result, the magnetic tape taken out of the magnetic tape cartridge of Example 1 had an SNR value 2 dB higher than that of the magnetic tape produced without the vertical orientation treatment. In an environment with a temperature of 23°C and a relative humidity of 50%, 10 passes of recording and reproduction were performed with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. The relative speed between the magnetic tape and the magnetic head was 6 m / sec. Recording was performed using a MIG (Metal-in-gap) head (gap length 0.15 μm, track width 1.0 μm) as the recording head, and the recording current was set to the optimal recording current for each magnetic tape. Reproduction was performed using a GMR (Giant-magnetoresistive) head (element thickness 15 nm, shield spacing 0.1 μm, reproduction element width 0.8 μm) as the reproduction head. A signal with a linear recording density of 300 kfci was recorded, and the reproduction signal was measured with a spectrum analyzer manufactured by Shibasoku. The unit kfci is the unit of linear recording density (not convertible to SI units). The signal was used at a portion where the signal was sufficiently stable after the magnetic tape started running. [Industrial Applicability]

[0166] One aspect of the present invention is useful in the technical fields of various data storage such as archives.

Claims

1. A magnetic tape cartridge in which a magnetic tape is wound around a cartridge reel, The magnetic tape has a non-magnetic support and a magnetic layer containing a ferromagnetic powder, the magnetic layer has a plurality of servo bands; The following five magnetic tape deformations: Deformation of magnetic tape after one year of storage in an environment of 16°C and 20% relative humidity. The deformation of the magnetic tape after one year of storage in an environment of 16°C and 80% relative humidity. Deformation of magnetic tape after one year of storage in an environment of 26°C and 80% relative humidity. Deformation of magnetic tape after one year of storage in an environment of 32°C and 20% relative humidity. Deformation of magnetic tape after one year of storage in an environment of 32°C and 55% relative humidity. The maximum value is 0.50 μm or less, The rate of change in the amount of deformation of the magnetic tape relative to the change in relative humidity, calculated from the five amounts of deformation of the magnetic tape, is 0.0001 μm / % or more and 0.0500 μm / % or less, and A rate of change in the amount of deformation of the magnetic tape relative to a change in temperature, calculated from the five amounts of deformation of the magnetic tape, is equal to or greater than 0.0010 μm / ° C. and equal to or less than 0.1000 μm / ° C., A magnetic tape cartridge, wherein the deformation amount of the magnetic tape is the maximum value of the absolute value of the difference between before and after storage of all servo band intervals at each measurement position measured at 1 m intervals along the entire length of the magnetic tape.

2. 2. The magnetic tape cartridge according to claim 1, wherein the maximum value of said five magnetic tape deformation amounts is 0.01 [mu]m or more and 0.50 [mu]m or less.

3. 3. The magnetic tape cartridge according to claim 1, wherein the magnetic tape further comprises a non-magnetic layer containing a non-magnetic powder between the non-magnetic support and the magnetic layer.

4. 4. The magnetic tape cartridge according to claim 1, wherein the magnetic tape further comprises a backcoat layer containing a nonmagnetic powder on a surface side of the nonmagnetic support opposite to the surface side having the magnetic layer.

5. 5. The magnetic tape cartridge according to claim 1, wherein the non-magnetic support is an aromatic polyester support.

6. 6. The magnetic tape cartridge of claim 5, wherein said aromatic polyester support is a polyethylene terephthalate support.

7. 6. The magnetic tape cartridge of claim 5, wherein said aromatic polyester support is a polyethylene naphthalate support.

8. 5. The magnetic tape cartridge according to claim 1, wherein the non-magnetic support is an aromatic polyamide support.

9. 9. The magnetic tape cartridge according to claim 1, wherein the squareness of the magnetic tape in the perpendicular direction is 0.60 or more.

10. A magnetic recording and reproducing device comprising the magnetic tape cartridge according to any one of claims 1 to 9.

11. 11. The magnetic recording and reproducing apparatus according to claim 10, further comprising a magnetic head having a reproducing element width of 0.8 [mu]m or less.

12. the magnetic tape cartridge; A take-up reel; Including, The magnetic tape is run between the take-up reel and the cartridge reel of the magnetic tape cartridge under tension in the longitudinal direction of the magnetic tape, the maximum value of the tension being 0.50 N or more; and 12. The magnetic recording and reproducing device according to claim 10, wherein the magnetic tape after being run under said tension is wound around a cartridge reel of the magnetic tape cartridge under a tension of 0.40 N or less in the longitudinal direction of the magnetic tape.

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