Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus

Abstract

To provide a magnetic tape which has no leader tape and is excellent in running stability.SOLUTION: Provided are a magnetic tape including a non-magnetic support and a magnetic layer including ferromagnetic powder, and a magnetic tape cartridge and a magnetic tape device including the magnetic tape. The magnetic tape is a data tape in which a leader pin is directly attached to an end portion, wherein in an end portion region of the surface of the magnetic layer on the leader pin attachment side, a frictional force F10 ° with respect to an LTO9 head measured at a head inclination angle of 10 ° is 4 gf to 15 gf, and the end portion region on the leader pin attachment side is a region within a range from a 5 cm position to a 20 cm position with an end of the end portion on the leader pin attachment side of the data tape as a start point 0 cm position in the longitudinal direction position.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Magnetic recording media are available in tape and disk form, and tape-type magnetic recording media, that is, magnetic tape, are primarily used for data storage applications such as data backup and archiving (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2016-524774 [Patent Document 2] US2019 / 0164573A1 [Patent Document 3] Patent No. 6590102 specification Summary of the Invention [Problem to be solved by the invention]

[0004] A typical magnetic tape has a structure in which a data tape and a leader tape are joined together by a splice tape. In the present invention and this specification, a "data tape" is a magnetic tape on which data is recorded, and which usually has a servo pattern formed thereon. In contrast, no data is recorded on the "leader tape." Leader tape is usually a tape that does not have a servo pattern formed on it. A leader pin is usually attached to the end of the leader tape. The leader pin is attached to the outer end of the magnetic tape housed in a magnetic tape cartridge. When the magnetic tape cartridge is loaded into a magnetic tape device, the leader pin is pulled out while being engaged by the pull-out member of the magnetic tape device, and is attached to the take-up reel of the magnetic tape device.

[0005] FIG. 15 is a perspective view of an example of a state in which a magnetic tape having a leader tape is pulled out from a magnetic tape cartridge. In Figure 15, the magnetic tape cartridge 13 has a cartridge case 132 in which an upper case 132a and a lower case 132b are fastened together with screws or the like. A leader pin 133 is attached to the outer tape end of the magnetic tape MT. At the other end of the magnetic tape MT, the end of the data tape is usually wound around a cartridge reel 135. An opening 132c for pulling out the magnetic tape MT is formed in one side wall of the cartridge case 132, and this opening 132c is opened and closed by a sliding door 136 that is biased in the closing direction by elastic means (not shown). Furthermore, when the magnetic tape cartridge 13 is not in use, with the magnetic tape MT completely wound around the cartridge reel 135, the leader pin 133 attached to the tape end is locked in a recessed storage portion 132d formed near the opening 132c.

[0006] Although not shown in Figure 15, a center hole is formed in the center of lower case 132b to rotate cartridge reel 135 using the drive shaft of the magnetic tape device, and a rotation restriction mechanism (not shown) is provided in the center of cartridge reel 135 to restrict rotation of cartridge reel 135 when not in use. A reel plate is attached to the bottom of cartridge reel 135 in the center to attract and hold magnetic rotation drive means, and a reel gear that meshes with the drive gear of the rotation drive means is formed on the outer periphery. When the reel gear and drive gear are meshed, the rotation restriction mechanism is released and cartridge reel 135 is allowed to rotate freely.

[0007] The leader pin 133 is attached to the end of the leader tape LT of the magnetic tape MT using a clamp 138 having a C-shaped cross section.

[0008] Fig. 16 is a cross-sectional view of an example of a state in which a data tape and a leader tape are joined by a splicing tape. In the example shown in Fig. 16, a leader tape LT is joined by a splice tape ST with one end of the leader tape LT butted against one end of a data tape DT.

[0009] In response to this, the inventors have investigated attaching a leader pin directly to the data tape without providing a leader tape. That is, they have investigated magnetic tapes without leader tapes. However, as a result of their investigations, it has become clear that magnetic tapes without leader tapes tend to have poor running stability.

[0010] In view of the above, an object of one aspect of the present invention is to provide a magnetic tape that does not have a leader tape and that has excellent running stability. [Means for solving the problem]

[0011] One aspect of the present invention is as follows. [1] A magnetic tape having a non-magnetic support and a magnetic layer containing ferromagnetic powder, The magnetic tape is a data tape with a leader pin directly attached to the end thereof, The friction force F against the LTO (Linear Tape-Open) head measured at a head tilt angle of 10° in the edge region of the surface of the magnetic layer on the side where the leader pin is attached is 10° (Hereinafter referred to as “F 10° (Leader pin attachment end region) is 4 gf or more and 15 gf or less, The leader pin attachment end region is a region within a range from 5 cm to 20 cm from the end of the leader pin attachment end of the data tape, which is the starting point 0 cm in the longitudinal direction. [2] The arithmetic mean peak curvature Spc of the surface of the magnetic layer as defined in ISO (International Organization for Standardization) 25178 (hereinafter referred to as "Spc of the magnetic layer surface" or simply "Spc") is 0.30 (1 / μm) or more and 0.70 (1 / μm) or less, and The magnetic tape according to [1], wherein the standard deviation σ of the Spc in the width direction of the surface of the magnetic layer (hereinafter also referred to as "width direction σ of Spc") is 0.15 (1 / μm) or less. [3] The magnetic tape according to [1] or [2], wherein the magnetic layer further contains non-magnetic powder having an average plate diameter of 50 nm or more and 1000 nm or less and an average plate thickness of 12 nm or less. [4] The magnetic tape according to any one of [1] to [3], further comprising a non-magnetic layer containing non-magnetic powder between the non-magnetic support and the magnetic layer. [5] The non-magnetic powder of the non-magnetic layer has an average particle volume of 2.0 × 10 -6 μm 3 The magnetic tape according to [4], comprising the following Fe-based inorganic oxide powder: [6] The magnetic tape according to [4] or [5], wherein the non-magnetic powder in the non-magnetic layer contains carbon black having a pH of 9.0 or less. [7] The magnetic tape according to any one of [4] to [6], wherein the thickness of the non-magnetic layer is 0.1 μm or more and 0.7 μm or less. [8] The magnetic tape according to any one of [1] to [7], further comprising a backcoat layer containing non-magnetic powder on the surface of the non-magnetic support opposite to the surface having the magnetic layer. [9] The magnetic tape according to any one of [1] to [8], wherein the tape thickness of the data tape is 5.2 μm or less.

[10] The magnetic tape according to any one of [1] to [9], wherein the tape thickness of the data tape is 5.0 μm or less.

[11] The magnetic tape according to any one of [1] to

[10] , wherein the squareness ratio of the data tape in the perpendicular direction is 0.60 or more.

[12] The magnetic tape according to any one of [1] to

[11] , wherein the squareness ratio of the data tape in the vertical direction is 0.65 or more.

[13] A magnetic tape described in any one of [1] to

[12] , wherein the end of the data tape to which the leader pin is directly attached further has a reinforcing layer on at least one of the magnetic layer side and the side opposite to the magnetic layer side.

[14] The magnetic tape according to

[13] , wherein the reinforcing layer has a thickness of 10.0 μm or more.

[15] The arithmetic mean curvature Spc of the peaks of the surface of the magnetic layer as defined in ISO 25178 is 0.30 (1 / μm) or more and 0.70 (1 / μm) or less, the standard deviation σ of the Spc in the width direction of the surface of the magnetic layer is 0.15 (1 / μm) or less; the magnetic layer further contains non-magnetic powder having an average plate diameter of 50 nm or more and 1000 nm or less and an average plate thickness of 12 nm or less, the data tape further comprises a non-magnetic layer between the non-magnetic support and the magnetic layer, the non-magnetic layer containing a non-magnetic powder; The non-magnetic powder of the non-magnetic layer has an average particle volume of 2.0×10 -6 μm 3 The present invention comprises the following Fe-based inorganic oxide powder and carbon black having a pH of 9.0 or less: the thickness of the non-magnetic layer is 0.1 μm or more and 0.7 μm or less, the data tape further comprises a backcoat layer containing a nonmagnetic powder on a surface of the nonmagnetic support opposite to the surface having the magnetic layer; The data tape has a thickness of 5.0 μm or less, The squareness ratio of the data tape in the vertical direction is 0.65 or more, and The magnetic tape according to [1], wherein the end of the data tape to which the leader pin is directly attached further has a reinforcing layer having a thickness of 10.0 μm or more on at least one of the magnetic layer side and the side opposite to the magnetic layer side.

[16] A magnetic tape cartridge comprising the magnetic tape according to any one of [1] to

[15] .

[17] A magnetic tape device including the magnetic tape according to any one of [1] to

[15] .

[18] Further comprising a magnetic head; the magnetic head has a module including an element array having a plurality of magnetic head elements between a pair of servo signal read elements; The magnetic tape device according to

[17] , wherein the angle θ formed by the axis of the element array with respect to the width direction of the magnetic tape is changed while the magnetic tape is running within the magnetic tape device. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to provide a magnetic tape that does not have a leader tape and that has excellent running stability, and also to provide a magnetic tape cartridge and a magnetic tape device that include such a magnetic tape. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a portion of an example of a magnetic tape. [Figure 2] 1 is a cross-sectional view showing a portion of an example of a magnetic tape provided with a reinforcing layer. [Figure 3] An example of a track profile is shown, with the horizontal axis representing the track position and the vertical axis representing the output of the reproduced signal. [Figure 4] 1 shows an example of a graph relating to an initial nonlinear component. [Figure 5] 10 shows an example of a graph regarding the nonlinear component after storage. [Figure 6] 10 is an example of a graph showing the absolute value of the difference between the initial nonlinear component and the nonlinear component after storage for each reproducing element (the difference between the nonlinear component before and after storage). [Figure 7] FIG. 2 is a schematic diagram showing an example of a magnetic head module. [Figure 8] 1 is an explanatory diagram of the relative positional relationship between a module and a magnetic tape while the magnetic tape is running in a magnetic tape device. [Figure 9] FIG. 10 is an explanatory diagram regarding changes in angle θ while the magnetic tape is running. [Figure 10] An example of a manufacturing process for a magnetic tape (schematic diagram) is shown. [Figure 11] 1 shows an example of the arrangement of data bands and servo bands. [Figure 12] An example of servo pattern layout for an LTO (Linear Tape-Open) Ultrium format tape is shown below. [Figure 13] FIG. 10 is an explanatory diagram of a method for measuring an angle θ while a magnetic tape is running. [Figure 14] FIG. 1 is a schematic diagram illustrating an example of a magnetic tape device. [Figure 15] 1 is a perspective view of an example of a state in which a magnetic tape having a leader tape is pulled out from a magnetic tape cartridge. [Figure 16] 1 is a cross-sectional view of an example of a state in which a data tape and a leader tape are joined by a splicing tape. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, magnetic tapes, magnetic tape cartridges, and magnetic tape devices will be described with reference to the drawings. However, the embodiments shown in the drawings are merely examples, and the present invention is not limited to the embodiments shown in the drawings.

[0015] [Magnetic tape] One aspect of the present invention relates to a magnetic tape having a non-magnetic support and a magnetic layer containing ferromagnetic powder, the magnetic tape being a data tape with a leader pin directly attached to the end, and the frictional force F against an LTO9 head measured at a head tilt angle of 10° in the end region of the surface of the magnetic layer on the side where the leader pin is attached. 10° (F 10° The force (leader pin attachment end region) is 4 gf or more and 15 gf or less. The leader pin attachment end region is a region ranging from 5 cm to 20 cm from the end of the leader pin attachment end of the data tape, which is the starting point (0 cm) in the longitudinal direction. In this invention and this specification, the "surface of the magnetic layer" is synonymous with the magnetic layer side surface of the magnetic tape. Furthermore, in terms of units, "gf" indicates gram force, and 1 N (Newton) is approximately 102 gf.

[0016] The inventors of the present invention have conducted extensive research into improving the running stability of data tapes in which the leader pin is directly attached to the end, i.e., magnetic tapes that do not have a leader tape, and have found that F 10° It has been newly discovered that data tapes with a leader pin attachment end region in the above range can exhibit excellent running stability even when the leader pin is attached directly to the end of the data tape and the tape is run without a leader tape. The magnetic tape will now be described in more detail.

[0017] <F 10° (Leader pin attachment end area) Fig. 1 is a cross-sectional view showing a portion of an example of a magnetic tape. The magnetic tape shown in Fig. 1 does not have a leader tape, and is attached directly to a leader pin 133 at the end of a data tape DT using a clamp 138. The side of the data tape DT that is wound around the leader pin 133 is the magnetic layer side or the opposite side, and is preferably the magnetic layer side. In this invention and this specification, the "leader pin attachment end region" refers to the region ranging from 5 cm to 20 cm from the end of the leader pin attachment end of the data tape, which is the starting point of the longitudinal position at 0 cm (see Figure 1).

[0018] In the present invention and this specification, an "LTO9 head" is a magnetic head that complies with the LTO9 standard. 10° To measure the area (the end area on the side where the leader pin is attached), the magnetic head mounted on the LTO9 drive may be removed and used, or a commercially available magnetic head for LTO9 drives may be used. Here, an LTO9 drive is a drive (magnetic tape device) that complies with the LTO9 standard. The same applies to drives of other generations. In addition, for the magnetic tape to be measured, the F 10° When measuring the area (the end area on the side where the leader pin is attached), a new (i.e., unused) LTO9 head shall be used. Note that the LTO9 standard is a standard that can accommodate the recent trend toward high-density recording, 10° The magnetic tape is not limited to that used in an LTO9 drive. Data may be recorded and / or reproduced on the magnetic tape in an LTO9 drive, or in a next-generation drive, or in a drive of an earlier generation than LTO9, such as an LTO8 drive.

[0019] The LTO9 head has three modules, each containing an element array with multiple magnetic head elements between a pair of servo signal read elements. The three modules are arranged in the LTO9 head in the following order: write module - read module - write module (total number of modules: 3).

[0020] Each module includes an element array, i.e., an array of elements, with a total of 32 magnetic head elements between a pair of servo signal read elements. A module with a write element as a magnetic head element is a recording module for recording data to magnetic tape. A module with a read element as a magnetic head element is a playback module for reproducing data recorded on magnetic tape. In an LTO9 head, the three modules are arranged with the axes of the element arrays of each module oriented parallel. This "parallel" does not necessarily mean "parallel" in the strict sense, but also includes the range of error normally accepted in the technical field to which the present invention pertains. The range of error can mean, for example, a range of ±10° or less from strict parallelism.

[0021] F 10° The head tilt angle in the measurement (at the end area on the leader pin mounting side) is the head tilt angle in the playback module of the LTO9 head.

[0022] In each element array, a pair of servo signal read elements and multiple magnetic head elements (i.e., write elements or read elements) are arranged linearly and spaced apart. Here, "arranged linearly" means that each magnetic head element is arranged on a straight line connecting the center of one servo signal read element to the center of the other servo signal read element. Furthermore, the "axis of the element array" in this invention and this specification refers to the straight line connecting the center of one servo signal read element to the center of the other servo signal read element. Other details of the magnetic head and the head tilt angle will be described later.

[0023] In the present invention and herein, F 10° Measurement of the (leader pin attachment end area) shall be carried out in an environment of 23°C and 50% relative humidity using the following method. Also, F 10°The head tilt angle for measurement (at the end region on the leader pin mounting side) refers to the angle formed by the axis of the element array in the playback module of the LTO9 head with respect to the direction perpendicular to the sliding direction during the first outward movement of the following 100 back-and-forth sliding. This angle is the angle θ formed by A in Figure 8 (described below) and the axis of the element array (B in Figure 8), where A is interpreted as the direction perpendicular to the sliding direction. The head tilt angle is fixed during the 100 back-and-forth sliding. A tape sample including the leader pin attachment end region is cut out from the magnetic tape (i.e., data tape) to be measured. The leader pin is removed before or after cutting. The tape sample thus prepared is placed on two cylindrical guide rolls, each 1 inch in diameter (1 inch = 2.54 cm), arranged parallel to and spaced from each other, so that a randomly selected portion of the leader pin attachment end region of the magnetic layer surface is in contact with the rolls. To extend the tape length, a commercially available guide tape or the like may be attached to the surface of the tape sample opposite the magnetic layer. The randomly selected portion of the leader pin attachment end region of the magnetic layer surface of the tape sample is slid against the LTO9 head with a head tilt angle of 10°. Note that if a reinforcing layer (described later) is laminated in part of the leader pin attachment end region of the magnetic layer surface, a randomly selected portion of the leader pin attachment end region of the magnetic layer surface other than the area where the reinforcing layer is laminated is slid in the manner described above. The resistance force generated during the sliding is detected by a strain gauge. 100 reciprocating slides are performed. The measurement conditions are a wrap angle θ of 6° and a sliding speed of 30 mm / sec. The tension applied to the tape sample in the longitudinal direction during sliding is 0.55 N. The sliding distance for each of the forward and backward passes is 5 cm. The dynamic friction force during the 100th forward pass is expressed as F 10°(the end region on the side where the leader pin is attached). During the above measurement, one of the ends of the tape sample in the longitudinal direction is connected to a strain gauge, and a tension of 0.20 N is applied to the other end. In the case of a tape sample in which the tape length is extended using a guide tape or the like, one or both of the ends may be the end of the guide tape or the like. The tension applied here is T0 (unit: N), and the resistance force detected by the strain gauge is T (unit: N), and the friction force F value is calculated using the following formula. That is, here, the friction force F is calculated as T0 = 0.20. Before measurement, the tape sample is left for at least 24 hours while placed on the guide roll as described above to allow it to acclimate to the measurement environment.

[0024]

number

[0025] The friction force F obtained by the above method is calculated as F of the magnetic tape to be measured. 10° (Leader pin attachment end area). F 10° Regarding the head tilt angle of 10° when measuring the head tilt angle (leader pin attachment end region), there are cases where the head tilt angle is changed while the magnetic tape is running to record and / or play back data (details will be described later), and 10° was adopted as an exemplary value of the angle that can be adopted in such cases. Therefore, the head tilt angle when recording data to the magnetic tape and playing back recorded data is not limited to 10°. Furthermore, the temperature and humidity of the measurement environment are adopted as exemplary values ​​of the temperature and humidity of the environment in which recording and / or playing back of the magnetic tape is performed. Therefore, the environment in which data is recorded to the magnetic tape and played back recorded data is not limited to the above temperature and humidity environments.

[0026] F of the above magnetic tape 10° (Leader pin attachment end region) is 4 gf or more and 15 gf or less from the viewpoint of improving running stability. 10°(Leader pin attachment side end region) is preferably 14 gf or less, more preferably 13 gf or less, 12 gf or less, 11 gf or less, 10 gf or less, 9 gf or less, 8 gf or less, 7 gf or less, and 6 gf or less in that order. F of the above magnetic tape 10° The (leader pin attachment side end region) can be adjusted, for example, by the types of components used to prepare the magnetic layer, etc. Details of this point will be described later.

[0027] <Spc of the magnetic layer surface and σ of Spc in the width direction> Incidentally, data is typically recorded on magnetic tape by running the magnetic tape in a magnetic tape device (commonly called a "drive") and recording data on the data band by moving a magnetic head along 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 tape device and the magnetic head is moved along 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 typically stored wound on a reel inside a magnetic tape cartridge or the like until the next recording and / or reproduction is performed.

[0028] To improve the accuracy with which a magnetic head tracks the data band of a magnetic tape during the above-described recording and / or playback, systems that perform head tracking using servo signals (hereinafter referred to as "servo systems") have been put into practical use. However, when recording and / or playback is performed after the above-described storage, deformation of the magnetic tape width caused by storage can cause the magnetic head for recording and / or playback of data to deviate from the target track position (commonly referred to as "off-track"). Off-track can cause overwriting of recorded data, playback problems, and other issues, reducing the operational stability of the drive. In recent years, the track density has increased along with the increase in magnetic tape capacity, making off-track more likely to occur, and therefore there is a growing need for improved operational stability of the drive. Meanwhile, in the data storage field, long-term data storage, known as archiving, has become common. However, generally, the longer the storage period, the more likely the magnetic tape width deformation occurs, and the frequency of off-track tends to increase.

[0029] Therefore, the present inventor believes that it will be desirable in the future for magnetic tapes to contribute to improving the operational stability of drives during recording and / or playback after long-term storage. As a result of extensive research into this point, the present inventor has come to the following new findings.

[0030] As described above, tape width deformation caused by long-term storage can cause a decrease in the operational stability of the magnetic tape in a drive. In response to this issue, a method has been proposed in recent years for obtaining widthwise dimensional information of a running magnetic tape using a servo signal and varying the angle at which the axial direction of the magnetic head module is tilted relative to the widthwise direction of the magnetic tape (referred to as the "head tilt angle") based on the obtained dimensional information (see Patent Documents 1 and 2, e.g., paragraphs 0059-0067 and 0084 of Patent Document 1). Another method for controlling the widthwise dimension of a magnetic tape is obtaining widthwise dimensional information of a running magnetic tape using a servo signal and adjusting the tension applied to the magnetic tape in the longitudinal direction based on the obtained dimensional information (see, for example, paragraph 0171 of Patent Document 3). For example, the above-described method for dynamically controlling the track position of a running magnetic tape can be used to suppress off-track motion. However, in the course of extensive research into further improving the operational stability of drives during recording and / or playback after long-term storage, the inventors have noticed that there may be off-track factors that are difficult to compensate for using dynamic track position control means. This point will be explained further below. When dynamic track position control is performed by changing the head tilt angle, the pitch of the magnetic head elements (specifically, the recording element and / or the reproducing element) changes uniformly depending on the head tilt angle, regardless of the position in the tape width direction. When dynamic track position control is performed by adjusting the tension applied to the magnetic tape in the longitudinal direction, the tension is usually adjusted across the entire tape width, so tension adjustment results in uniform changes in the tape width regardless of the position in the tape width direction. If the degree of tape width deformation is uniform across the magnetic tape, i.e., if the tape width deformation component is only a linear component, it is possible to completely compensate for off-track using the control means. Therefore, it is possible to completely align the data track and the magnetic head element. On the other hand, if the degree of tape width deformation varies unevenly depending on the position, i.e., if the tape width deformation component includes a nonlinear component, it is difficult for the control means to compensate for off-track caused by the nonlinear component. The inventors believed that reducing this nonlinear component could contribute to suppressing deterioration in drive operational stability due to off-track factors that are difficult to compensate for using dynamic track position control means. In this regard, the inventors believe that the Spc of the magnetic layer surface of a data tape of 0.30 (1 / μm) or more and 0.70 (1 / μm) or less, and the standard deviation σ of Spc of 0.15 (1 / μm) or less, can contribute to suppressing the occurrence of the nonlinear component of the tape width deformation. Furthermore, the inventors believe that the inclusion of a leader tape in a magnetic tape is one cause of the occurrence of the nonlinear component of the tape width deformation. In other words, the inventors believe that the magnetic tape having a leader pin attached directly to the data tape without a leader tape can also contribute to suppressing the occurrence of the nonlinear component of the tape width deformation.

[0031] (Measurement method) In the present invention and this specification, Spc is the arithmetic mean peak curvature Spc defined in ISO 25178. ISO 25178 is an ISO standard related to three-dimensional surface texture parameters, and more specifically, is ISO 25178-2:2021 (Geometrical product specifications (GPS) - Surface texture: Area - Part 2: Terms, definitions and surface texture parameters). To determine the Spc of the magnetic layer surface, measurements are made on the surface of the magnetic layer of the magnetic tape using an atomic force microscope (AFM) as follows. The measurement area is a 40 μm square (40 μm × 40 μm) area. Measurements are performed at five randomly selected locations on the magnetic layer surface, excluding the end region on the leader pin attachment side, as follows: The five locations where measurements are performed on the magnetic layer surface are five locations with the same longitudinal position but different widthwise positions. The longitudinal positions are selected randomly on the magnetic layer surface, and the width is divided into five sections relative to the magnetic tape width at this longitudinal position (i.e., if the magnetic tape width is W, then the width of each section is "W / 5"). Spc, as defined in ISO 25178, is determined for a randomly selected 40 μm square (40 μm × 40 μm) area in each section. Spc can be calculated using known AFM data analysis software. An example of AFM data analysis software is the AFM data analysis software (Nanoscope Analysis) provided by BRUKER. The arithmetic average of the five measured values ​​thus determined is the Spc of the magnetic layer surface of the magnetic tape being measured. The standard deviation σ (ie, the positive square root of the variance) of the five measured values ​​thus obtained is defined as the standard deviation σ of Spc in the width direction of the surface of the magnetic layer of the magnetic tape being measured (Spc width direction σ). The following measurement conditions can be given as an example of the AFM measurement conditions. An AFM (Bruker Nanoscope 5) was used in peak force tapping mode to measure an area of ​​40 μm × 40 μm on the surface of the magnetic layer of the magnetic tape. A Bruker SCANASYST-AIR probe was used, with a resolution of 512 pixels × 512 pixels and a scan speed of 512 seconds per screen (512 pixels × 512 pixels).

[0032] (Spc of magnetic layer surface) From the viewpoint of improving the operational stability of the drive during recording and / or playback after long-term storage, the Spc of the magnetic layer surface is preferably 0.30 (1 / μm) or more, more preferably 0.40 (1 / μm) or more, and even more preferably 0.50 (1 / μm) or more. Also from the above viewpoint, the Spc of the magnetic layer surface is preferably 0.70 (1 / μm) or less, and more preferably 0.60 (1 / μm) or less.

[0033] (Spc width direction σ) The standard deviation σ of the Spc in the width direction of the surface of the magnetic layer of the magnetic tape (i.e., data tape) (the width direction σ of Spc) is preferably 0.15 (1 / μm) or less, more preferably 0.14 (1 / μm) or less, and even more preferably 0.13 (1 / μm) or less, 0.12 (1 / μm) or less, 0.11 (1 / μm) or less, and 0.10 (1 / μm) or less, in that order. The width direction σ of Spc can be, for example, 0.00 (1 / μm) or more, 0.01 (1 / μm) or more, 0.05 (1 / μm) or more, or 0.08 (1 / μm) or more. From the viewpoint of improving the operational stability of the drive during recording and / or playback after long-term storage, it is presumed that the smaller the value of the width direction σ of Spc, the more preferable.

[0034] The method for controlling the Spc on the surface of the magnetic layer and the method for controlling the Spc in the width direction σ will be described later.

[0035] <Nonlinear component of tape width deformation> The inventors believe that the "nonlinear component in the tape width direction resulting from storage for 20 days in an environment with a temperature of 60°C and a relative humidity of 20%," which can be determined by the following method, can serve as an indicator of the nonlinear component of the tape width deformation described above. Note that the storage condition of "storage for 20 days in an environment with a temperature of 60°C and a relative humidity of 20%" is adopted as an example of storage conditions in an accelerated environment equivalent to long-term data storage known as archiving, and the magnetic tape described above is not limited to those stored under such storage conditions. Unless otherwise specified, the following operations and measurements are carried out in an environment with a temperature of 20 to 25°C and a relative humidity of 40 to 60%. The magnetic tape to be measured must be a data tape with a length (including the part where the leader pin is attached) of 200m or more. If the magnetic tape to be measured is housed in a magnetic tape cartridge, remove the magnetic tape from the magnetic tape cartridge. The magnetic tape to be measured is wound onto a magnetic tape reel with a hub diameter (outer diameter, the same applies below) of 44 mm, with a tension of 0.6 N (Newton) applied to the magnetic tape in the longitudinal direction using a device with a winding mechanism that applies tension to the magnetic tape in the longitudinal direction.The magnetic tape thus wound onto the reel is stored for at least 24 hours in an environment with a temperature of 20 to 25°C and a relative humidity of 40 to 60% before the following measurements. Regarding one end and the other end of the magnetic tape, the end closest to the start point of winding onto the reel is called the inner end of the tape, and the other end is called the outer end of the tape. Here, the inner end of the tape is the end of the tape on the side where the leader pin is attached, and in the case of magnetic tape without a leader tape, it is the end of the data tape on the side where the leader pin is attached. The following measurements are performed with the leader pin attached. The outer end of the tape is the end of the tape opposite the side where the leader pin is attached, and is usually the end of the data tape. The following measurements are performed in an area within 100 m from the end of the outer end of the data tape (hereinafter referred to as the "outer tape area") and an area within 100 m from the end of the inner end of the data tape (hereinafter referred to as the "inner tape area"), at the center wrap of each data band. The following measurements were performed using a magnetic head equipped with a reproducing module including an element array with 10 or more channels of reproducing elements with an element width (specifically, reproducing element width) of 0.2 μm to 1.0 μm between a pair of servo signal read elements, and a recording module including an element array with 10 or more channels of recording elements with an element width (specifically, recording element width) of 1.2 μm to 2.9 μm between a pair of servo signal read elements. "Element width" refers to the physical dimension of the element width and can be measured using an optical microscope, scanning electron microscope, or the like. In the recording module, the spacing between two adjacent recording elements in the head width direction is 83.25 μm. In the reproducing module, the spacing between two adjacent reproducing elements in the head width direction is 83.25 μm. The spacing is the spacing between the centers of two adjacent recording elements in the recording module, and the spacing is the spacing between the centers of two adjacent reproducing elements in the reproducing module, and can be measured using an optical microscope, or the like. In the measurements for the examples and comparative examples described below, a magnetic head was used that included a recording module including an element array with 32 channels (0 to 31 channels) of recording elements between a pair of servo signal reading elements, and a reproducing module including an element array with 32 channels (0 to 31 channels) of reproducing elements between a pair of servo signal reading elements. The reel on which the magnetic tape to be measured is wound and the magnetic head are attached to the tape transport system of the magnetic tape device to record and play back data. The tape transport system is attached to a recording / playback amplifier capable of driving the magnetic head elements (specifically, the recording element and playback element) of the magnetic head. The recording / playback amplifier can be controlled from a computer (PC: Personal Computer) via a controller. The magnetic head is attached to an actuator (piezoelectric motor or VCM (voice coil motor)) that moves in the tape width direction. This allows servo following to be performed to maintain a constant track position based on the servo signal from the magnetic tape while the tape is running. To compensate for the linear component of tape width deformation, the head tilt angle of the magnetic head can be changed to dynamically control the track position so that the difference between the widthwise read positions PES (Position Error Signal) (PES1, PES2) based on the servo signals obtained by the upper and lower servo signal reading elements is kept constant. The servo following and dynamic track position control are performed during the following recording and playback operations. Next, while the magnetic tape is running at a constant speed of 3.0 m / s, a DC (Direct Current) pattern is recorded on the first wrap, a 255 kfci single-frequency signal is recorded on the second wrap, and a DC pattern is recorded on the third wrap for three consecutive wraps running in the same direction. The unit "kfci" is a unit of linear recording density (not convertible to SI units). Shingled recording is performed on three or more tracks so that the difference between (PES1 + PES2) / 2 is 1200 nm. Shingled recording is also called shingled recording. Next, data is reproduced over a 90-meter length from the center wrap of three consecutive wraps in an area within 100 meters of the outer edge of the tape (the outer tape area) and an area within 100 meters of the inner edge of the tape (the inner tape area). The reproduced signal waveforms and servo signal waveforms are acquired and saved using an oscilloscope. For each measurement, the track position of the reproducing element is moved across the tape width by an interval of less than 1 / 30 of the track pitch. The "reproduced signal output" is calculated for each reproducing element from the reproduced signal waveforms acquired and saved using the oscilloscope, and the track position is calculated from the servo signal waveform. From these results, a track profile is created, with track position plotted on the horizontal axis and reproduced signal output plotted on the vertical axis. Figure 3 shows an example of a track profile created in this way. The median value between two track positions where the output of the playback signal is 1 dB or more lower than the maximum value is found, and the median value is plotted on the vertical axis for each playback element. A linear approximation line is obtained by linear fitting using the least squares method. The difference between the linear approximation line and the actual measured value is found for each playback element in both the outer and inner tape regions, and this is defined as the "initial nonlinear component." Figure 4 shows an example of a graph related to the initial nonlinear component. In the example shown in Figure 4 and the example shown in Figure 5 (described later), the number of playback elements (channels) is 32 (playback element numbers (No.): channel 0 to channel 31). After measuring the initial nonlinear component as described above, the magnetic tape to be measured is wound onto a magnetic tape reel with a hub diameter of 44 mm, with a tension of 0.6 N applied to the magnetic tape in the longitudinal direction using a device with a winding mechanism that applies tension to the magnetic tape in the longitudinal direction. During this winding, the end of the tape that was the inner end of the tape when wound onto the reel before measuring the initial nonlinear component becomes the inner end of the tape. The magnetic tape wound onto the reel in this manner is stored in an environment at a temperature of 60°C and a relative humidity of 20% for 20 days. After the storage described above, the magnetic tape to be measured was stored wound on a reel in an environment with a temperature of 20-25°C and a relative humidity of 40-60% for at least 24 hours (but up to a maximum of 120 hours). Then, using the magnetic tape device used to measure the initial nonlinear components, the magnetic tape was run back and forth once (forward and reverse) over its entire length. Using the same recording element, reproducing element, magnetic tape device, and reproduction conditions as used in the measurement of the initial nonlinear components, data was reproduced over a length of 90 m in an area within 100 m from the outer edge of the tape (the outer tape area) and an area within 100 m from the inner edge of the tape (the inner tape area). The reproduced signal output and servo signal waveform were acquired and saved using the same oscilloscope used in the measurement of the initial nonlinear components. The track position of the reproducing element was moved across the tape width for each measurement at the same intervals as used in the measurement of the initial nonlinear components. The "reproduced signal output" for each reproducing element was calculated from the reproduced signal waveforms acquired and saved using the oscilloscope, and the track position was calculated from the servo signal waveforms. From these results, a track profile is created by plotting the track position on the horizontal axis and the playback signal output on the vertical axis. Figure 3 is an example of a track profile created in this way. The median value between two track positions where the playback signal output is 1 dB or more lower than the maximum value is found, and the median value is plotted on the vertical axis for each playback element. A linear approximation line is obtained by linear fitting using the least squares method. The difference between the linear approximation line and the actual measured value is found for each playback element for both the outer and inner tape regions, and this is defined as the "nonlinear component after storage." Figure 5 shows an example of a graph of the nonlinear component after storage. The absolute value of the difference between the "initial nonlinear component" and the "nonlinear component after storage" for each reproducing element (the difference in the nonlinear component before and after storage) is calculated. Figure 6 shows an example of a graph showing the absolute value of the difference calculated for each reproducing element in this way. The maximum value of the absolute value in the outer and inner tape regions is taken as the "nonlinear component of tape width deformation" of the magnetic tape being measured. The initial nonlinear component can be considered to be a nonlinear component caused by factors other than the magnetic tape. Therefore, the inventors believe that by calculating the difference in the nonlinear component before and after storage as described above, it is possible to accurately evaluate the nonlinear component caused by the magnetic tape.

[0036] The nonlinear component of tape width deformation determined for the magnetic tape by the method described above is preferably 90 nm or less, in order of preference, 85 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, and 50 nm or less, from the viewpoint of improving the operational stability of the drive during recording and / or playback after long-term storage. Having the Spc and width-direction σ of the Spc on the magnetic layer surface of the magnetic tape within the above ranges, and having a leader pin directly attached to the data tape without a leader tape, can contribute to controlling the value of the nonlinear component within the above range. Furthermore, the nonlinear component of tape width deformation can be, for example, 0 nm or more, more than 0 nm, 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, or 40 nm or more. From the viewpoint of improving the operational stability of the drive, the smaller the nonlinear component of tape width deformation, the more preferable.

[0037] <Explanation of head tilt angle> As described above, one example of a means for dynamically controlling the track position while the magnetic tape is running is to change the head tilt angle. In this regard, the configuration of the magnetic head, the head tilt angle, etc. will be described below. Furthermore, the reason why it is possible to dynamically control the track position while the magnetic tape is running by tilting the axial direction of the magnetic head module relative to the width direction of the magnetic tape while the magnetic tape is running will be described below.

[0038] The magnetic head may have one or more modules, two or more, or three or more, each module including an element array having a plurality of magnetic head elements between a pair of servo signal read elements. The total number of such modules may be, for example, five or less, four or less, or three or less, or the magnetic head may include a number of modules exceeding the total number exemplified here. Examples of arrangements of multiple modules include "recording module-playback module" (total number of modules: 2) and "recording module-playback module-recording module" (total number of modules: 3). However, this is not limited to the examples shown here.

[0039] Each module may include an element array, i.e., an array of elements, having multiple magnetic head elements between a pair of servo signal read elements. A module having a recording element as a magnetic head element is a recording module for recording data onto a magnetic tape data tape. A module having a reproducing element as a magnetic head element is a reproducing module for reproducing data recorded on the magnetic tape data tape. In a magnetic head, multiple modules are arranged, for example, in a recording / reproducing head unit, with the axes of the element arrays of each module oriented parallel. As described above, this "parallel" does not necessarily mean parallel in the strict sense, but also includes the range of error normally accepted in the technical field to which the present invention pertains. The range of error may, for example, mean a range of less than ±10° from strict parallelism.

[0040] In each element array, a pair of servo signal read elements and a plurality of magnetic head elements (i.e., write elements or read elements) are usually arranged linearly and spaced apart. Here, "arranged linearly" means, as described above, that each magnetic head element is arranged on a straight line connecting the center of one servo signal read element to the center of the other servo signal read element. In this invention and this specification, the "axis of the element array" means, as described above, the straight line connecting the center of one servo signal read element to the center of the other servo signal read element.

[0041] Next, the configuration of the module will be further described with reference to the drawings. However, the embodiments shown in the drawings are merely examples and do not limit the present invention.

[0042] FIG. 7 is a schematic diagram showing an example of a magnetic head module. The module shown in FIG. 7 has multiple magnetic head elements between a pair of servo signal read elements (servo signal read elements 1 and 2). A magnetic head element is also called a "channel." "Ch" in the diagram is an abbreviation for Channel. The module shown in FIG. 7 has a total of 32 magnetic head elements, Ch0 to Ch31.

[0043] In FIG. 7, "L" is the distance between a pair of servo signal read elements, i.e., the distance between one servo signal read element and the other servo signal read element. In the module shown in FIG. 7, "L" is the distance between servo signal read element 1 and servo signal read element 2. More specifically, it is the distance between the center of servo signal read element 1 and the center of servo signal read element 2. This distance can be measured, for example, using an optical microscope.

[0044] FIG. 8 is an explanatory diagram of the relative positional relationship between a module and a magnetic tape while the magnetic tape is running in a magnetic tape device. In FIG. 8, dotted line A indicates the width direction of the magnetic tape. Dotted line B indicates the axis of the element array. Angle θ can be said to be the head tilt angle while the magnetic tape is running, and is the angle formed by dotted lines A and B. When angle θ is 0° while the magnetic tape is running, the distance in the width direction of the magnetic tape between one servo signal read element and the other servo signal read element of the element array (hereinafter also referred to as the "effective distance between servo signal read elements") is "L". On the other hand, when angle θ is greater than 0°, the effective distance between the servo signal read elements is "L cos θ", and L cos θ is smaller than L. That is, "L cos θ" <L」である。

[0045] As described above, if the magnetic head for recording or reproducing data deviates from the target track position due to deformation of the magnetic tape (specifically, data tape) during recording or reproduction, it may result in overwriting of recorded data, playback failure, and other problems. For example, if the width of the data tape shrinks or expands, a magnetic head element that should be recording or reproducing data at the target track position may end up recording or reproducing data at a different track position. Furthermore, if the width of the data tape expands, the effective distance between servo signal reading elements may become shorter than the distance between two adjacent servo bands across a data band (also referred to as the "servo band distance" or "servo band distance"; specifically, the distance between the two servo bands in the width direction of the data tape), which may result in data not being recorded or reproduced near the edge of the data tape. In contrast, when the element array is tilted at an angle θ greater than 0°, the effective distance between the servo signal read elements becomes "Lcosθ," as explained above. The larger the value of θ, the smaller the value of Lcosθ, and the smaller the value of θ, the larger the value of Lcosθ. Therefore, by changing the value of θ according to the degree of dimensional change (i.e., contraction or expansion) in the width direction of the magnetic tape (specifically, data tape), it is possible to make the effective distance between the servo signal read elements approach or match the spacing between the servo bands. This can prevent or reduce the frequency of phenomena such as overwriting of recorded data or playback failures caused by the magnetic head for recording or playing back data being shifted from the target track position due to width deformation of the magnetic tape (specifically, data tape).

[0046] FIG. 9 is an explanatory diagram regarding the change in angle θ while the magnetic tape is running. θ is the angle θ at the start of travel initial can be set to, for example, greater than or equal to 0°. In Figure 9, the central diagram shows the state of the module at the start of travel. In Figure 9, the right figure shows the angle θ as θ initial The larger angle is angle θ c The effective distance between the servo signal reading elements is L cos θ. c is Lcosθ when the magnetic tape starts running initial It is preferable to make such an angle adjustment when the width of the data tape contracts during magnetic tape running. On the other hand, in Figure 9, the left figure shows the angle θ as θ initial The smaller angle θ e The effective distance between the servo signal reading elements is L cos θ. e is Lcosθ when the magnetic tape starts running initial It is preferable to make such an angle adjustment when the width of the data tape expands during magnetic tape running.

[0047] As explained above, changing the head tilt angle while the magnetic tape is running can contribute to preventing or reducing the frequency of such phenomena as overwriting of recorded data or playback failures caused by the magnetic head for recording or playing back data being displaced from the target track position due to width deformation of the magnetic tape (more specifically, data tape) during recording or playback. However, while dynamic track position control means such as those described above can usually compensate for off-track caused by the linear component of tape width deformation, it is difficult to suppress off-track caused by the nonlinear component. In contrast, in the magnetic tape described above, the Spc and width-direction σ of the Spc on the magnetic layer surface of the magnetic tape (i.e., data tape) are within the above range, and the leader pin is attached directly to the data tape without a leader tape. This is thought to contribute to reducing the nonlinear component of tape width deformation. This is thought to improve the operational stability of the drive. Such a magnetic tape is preferable for achieving higher track density.

[0048] <Data Tape> The magnetic tape may consist of only a continuous piece of data tape (i.e., no spliced ​​portions where two or more tapes are joined) that does not include a leader tape and has a leader pin directly attached to one end, or may have a reinforcing layer on at least one of the magnetic layer side and the side opposite to the magnetic layer side of the end of the data tape where the leader pin is directly attached. The data tape of the magnetic tape will be described in more detail below. The reinforcing layer will be described later.

[0049] <<Magnetic layer>> (Ferromagnetic powder) The ferromagnetic powder contained in the magnetic layer can be one or a combination of two or more known ferromagnetic powders used in the magnetic layers of various magnetic recording media. Using a ferromagnetic powder with a small average particle size is preferable 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.

[0050] Hexagonal ferrite powder A preferred example of the ferromagnetic powder is hexagonal ferrite powder. For details of the hexagonal ferrite powder, see, for example, JP 2011-225417 A, paragraphs 0012 to 0030, JP 2011-216149 A, paragraphs 0134 to 0136, JP 2012-204726 A, paragraphs 0013 to 0030, and JP 2015-127985 A, paragraphs 0029 to 0084.

[0051] In the present invention and this specification, "hexagonal ferrite powder" refers to a ferromagnetic powder in which a hexagonal ferrite crystal structure is detected as the main phase by X-ray diffraction analysis. The main phase refers to the structure to which the highest diffraction peak belongs in the X-ray diffraction spectrum obtained by X-ray diffraction analysis. For example, if the highest diffraction peak in the X-ray diffraction spectrum obtained by X-ray diffraction analysis is assigned to the hexagonal ferrite crystal structure, it is determined that the hexagonal ferrite crystal structure has been detected as the main phase. If only a single structure is detected by X-ray diffraction analysis, this detected structure is considered to be the main phase. The hexagonal ferrite crystal structure contains at least iron atoms, divalent metal atoms, and oxygen atoms as constituent atoms. Divalent metal atoms are metal atoms that can become divalent cations as ions, and examples of such atoms include alkaline earth metal atoms such as strontium atoms, barium atoms, and calcium atoms, and lead atoms. In the present invention and this specification, "hexagonal strontium ferrite powder" refers to a powder in which the main divalent metal atom contained therein is strontium atom, and "hexagonal barium ferrite powder" refers to a powder in which the main divalent metal atom contained therein is barium atom. "Main divalent metal atom" refers to the divalent metal atom that is the most abundant, on an atomic % basis, among the divalent metal atoms contained in the powder. However, rare earth atoms are not included in the above divalent metal atoms. In the present invention and this specification, "rare earth atom" refers to a powder selected from the group consisting of scandium atom (Sc), yttrium atom (Y), and lanthanoid atom. The lanthanoid atom is selected from the group consisting of lanthanum atom (La), cerium atom (Ce), praseodymium atom (Pr), neodymium atom (Nd), promethium atom (Pm), samarium atom (Sm), europium atom (Eu), gadolinium atom (Gd), terbium atom (Tb), dysprosium atom (Dy), holmium atom (Ho), erbium atom (Er), thulium atom (Tm), ytterbium atom (Yb), and lutetium atom (Lu).

[0052] Hereinafter, hexagonal strontium ferrite powder, which is one form of hexagonal ferrite powder, will be described in more detail.

[0053] The activation volume of the hexagonal strontium ferrite powder is preferably 800 to 1600 nm 3 The microparticulated hexagonal strontium ferrite powder exhibiting an activation volume in the above range is suitable for producing a data tape exhibiting excellent electromagnetic conversion characteristics. The activation volume of the hexagonal strontium ferrite powder is preferably in the range of 800 nm 3 or more, for example, 850 nm 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 It is even more preferable that the value 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 10 ...

[0054] "Activation volume" is a unit of magnetization reversal and is an index showing the magnetic size of a particle. The activation volume described in this invention and this specification and the anisotropy constant Ku described below are values ​​obtained by measuring the coercive force Hc using a vibrating sample magnetometer at magnetic field sweep speeds of 3 minutes and 30 minutes (measurement temperature: 23°C ± 1°C) in the coercive force Hc measurement section, and by using the following relational expression between Hc and activation volume V. Note that the unit of the anisotropy constant Ku is 1 erg / cc = 1.0 x 10 -1 J / m 3 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)]

[0055] The anisotropy constant Ku can be used as an index for reducing thermal fluctuation, in other words, improving thermal stability. The hexagonal strontium ferrite powder preferably has an anisotropy constant of 1.8×10 5 J / m 3 and more preferably 2.0×10 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 therefore preferred, the Ku value is not limited to the above-mentioned values.

[0056] 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 rare earth atoms unevenly distributed in the surface layer portion. In the present invention and this specification, the term "surface layer distribution of rare earth atoms" refers to the ratio of 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 layer content of rare earth atoms" or simply "surface layer content" with respect to rare earth atoms) to the ratio of 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" with respect to rare earth atoms), Rare earth atom surface content / rare earth atom bulk content > 1.0 This means that the ratio of "surface rare earth atom content / bulk rare earth atom content > 1.0" is satisfied. The rare earth atom content of the hexagonal strontium ferrite powder described below 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. When the surface rare earth atom content satisfies the ratio "surface rare earth atom content / bulk rare earth atom content > 1.0", this means that the rare earth atoms are unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder (i.e., present in greater amounts in the surface layer than in the interior). In the present invention and this specification, the surface layer refers to a partial region extending from the surface toward the interior of the particles constituting the hexagonal strontium ferrite powder.

[0057] 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 percent relative to 100 atomic percent of iron atoms. Having rare earth atoms in the above-mentioned bulk content range and having the rare earth atoms unevenly distributed in the surface layers of the particles constituting the hexagonal strontium ferrite powder is thought to contribute to suppressing a decrease in playback output during repeated playback. This is presumably because the hexagonal strontium ferrite powder contains rare earth atoms in the above-mentioned bulk content range and having the rare earth atoms unevenly distributed in the surface layers of the particles constituting the hexagonal strontium ferrite powder can increase the anisotropy constant Ku. The higher the anisotropy constant Ku, the more the occurrence of a phenomenon known as thermal fluctuation can be suppressed (in other words, thermal stability can be improved). By suppressing the occurrence of thermal fluctuation, the decrease in playback output during repeated playback 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 in the surface layer, thereby increasing the anisotropy constant Ku. Furthermore, it is believed that using a hexagonal strontium ferrite powder having rare earth atoms unevenly distributed in the surface layer as the ferromagnetic powder for the magnetic layer also contributes to preventing the magnetic layer surface from being worn away by friction with the magnetic head. That is, it is believed that a hexagonal strontium ferrite powder having rare earth atoms unevenly distributed in the surface layer can also contribute to improving the running durability of data tapes. This is believed to be because the uneven distribution of rare earth atoms on the surfaces of the particles that make up the hexagonal strontium ferrite powder contributes to improving the interaction between the particle surfaces and the organic substances (e.g., binders and / or additives) contained in the magnetic layer, thereby improving the strength of the magnetic layer. From the viewpoint of further suppressing a decrease in reproduction output during repeated reproduction 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 %.

[0058] The bulk content is the content determined 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 determined by completely dissolving the hexagonal strontium ferrite powder. The hexagonal strontium ferrite powder containing rare earth atoms may contain only one rare earth atom or two or more rare earth atoms. When two or more rare earth atoms are contained, the bulk content is determined for the total of the two or more rare earth atoms. This also applies to other components in the present invention and this specification. That is, unless otherwise specified, a certain component may be used alone or in combination with two or more. When two or more components are used, the content or content refers to the total of the two or more components.

[0059] When the hexagonal strontium ferrite powder contains rare earth atoms, the rare earth atoms may be any one or more of rare earth atoms. From the viewpoint of further suppressing the decrease in playback output during repeated playback, preferred rare earth atoms include neodymium atoms, samarium atoms, yttrium atoms, and dysprosium atoms, with neodymium atoms, samarium atoms, and yttrium atoms being more preferred, and neodymium atoms being even more preferred.

[0060] In a hexagonal strontium ferrite powder having rare earth atoms unevenly distributed in the surface layer, the rare earth atoms need only 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 a hexagonal strontium ferrite powder having rare earth atoms unevenly distributed in the surface layer, the ratio of the surface content of rare earth atoms determined by partial dissolution under the dissolution conditions described below to the bulk content of rare earth atoms determined by complete dissolution under the dissolution conditions described below, i.e., "surface content / bulk content," is greater than 1.0 and can be 1.5 or greater. A "surface content / bulk content" ratio greater than 1.0 means that the rare earth atoms are unevenly distributed in the surface layer (i.e., present in greater amounts than in the interior) in the particles constituting the hexagonal strontium ferrite powder. Furthermore, the ratio of the surface content of rare earth atoms determined by partial dissolution under the dissolution conditions described below to the bulk content of rare earth atoms determined by complete dissolution under the dissolution conditions described below, i.e., "surface 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 atoms unevenly distributed in the surface layers, it is sufficient that the rare earth atoms are unevenly distributed in the surface layers of the particles constituting the hexagonal strontium ferrite powder, and the above "surface content / bulk content" is not limited to the exemplified upper or lower limits.

[0061] The partial and total dissolution of hexagonal strontium ferrite powder is described below. For hexagonal strontium ferrite powder present as powder, sample powders to be partially and completely dissolved are collected from the same powder lot. On the other hand, for hexagonal strontium ferrite powder contained in the magnetic layer of a data tape, a portion of the hexagonal strontium ferrite powder removed from the magnetic layer is subjected to partial dissolution, and another portion is subjected to total dissolution. The hexagonal strontium ferrite powder can be removed from the magnetic layer by, for example, the method described in paragraph 0032 of JP 2015-91747 A. The term "partial dissolution" as used herein refers to dissolving the hexagonal strontium ferrite powder to such an extent that the remaining hexagonal strontium ferrite powder can be visually confirmed in the liquid at the end of dissolution. For example, partial dissolution can dissolve 10 to 20 mass% of the particles constituting the hexagonal strontium ferrite powder, with the total particles being 100 mass%. On the other hand, the term "complete dissolution" as used herein refers to dissolving the hexagonal strontium ferrite powder to such an extent that the remaining hexagonal strontium ferrite 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 is performed using an inductively coupled plasma (ICP) analyzer. This allows the surface content of rare earth atoms relative to 100 atomic percent iron atoms to be determined. If multiple types of rare earth atoms are detected by elemental analysis, the total content of all rare earth atoms is taken as the surface content. This also applies to measurements 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 determined by carrying out the same procedures as for the partial dissolution and surface layer content measurements described above.

[0062] From the viewpoint of increasing the reproduction output when reproducing data recorded on a data tape, it is desirable that the mass magnetization σs of the ferromagnetic powder contained in the data tape is high. In this regard, hexagonal strontium ferrite powder that contains rare earth atoms but does not have the rare earth atoms unevenly distributed in the surface layer tends to have a significantly lower σs than hexagonal strontium ferrite powder that does not contain rare earth atoms. On the other hand, hexagonal strontium ferrite powder that has the rare earth atoms unevenly distributed in the surface layer is considered preferable in order to suppress 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 is preferable, and 60A·m 2 / kg or less is more preferable. 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].

[0063] Regarding the content (bulk content) of 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 hexagonal strontium ferrite powder can contain only strontium atoms as divalent metal atoms. In another embodiment, the hexagonal strontium ferrite powder can contain one or more other divalent metal atoms in addition to strontium atoms. For example, barium atoms and / or calcium atoms can be contained. 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.

[0064] 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 these 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, the M-type hexagonal ferrite is AFe 12 O 19The composition formula is represented by the formula: where A represents a divalent metal atom. When the hexagonal strontium ferrite powder is of M type, A is only strontium atom (Sr). Alternatively, when A contains multiple divalent metal atoms, 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 crystalline structure of the hexagonal ferrite and is not particularly limited. The same applies to the iron atom content and oxygen atom content. The hexagonal strontium ferrite powder contains at least iron atoms, strontium atoms, and oxygen atoms, and may further contain rare earth atoms. 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 aluminum atoms (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 a decrease in playback output during repeated playback, 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 0 to 5.0 atomic %, relative to 100 atomic % of iron atoms, and may even be 0 atomic %. That is, in one embodiment, the hexagonal strontium ferrite powder may contain no atoms other than iron atoms, strontium atoms, oxygen atoms, and rare earth atoms. The content expressed in atomic % above is determined 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. Furthermore, in the present invention and this specification, "not containing" a certain atom means that the content is 0 mass % when completely dissolved and measured by an ICP analyzer. The detection limit of an ICP analyzer is usually 0.01 ppm (parts per million) or less by mass. The above term "free from" is used to mean that the substance is contained in an amount 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).

[0065] metal powder A preferred example of the ferromagnetic powder is ferromagnetic metal powder. For details of the ferromagnetic metal powder, see, for example, paragraphs 0137 to 0141 of JP-A No. 2011-216149 and paragraphs 0009 to 0023 of JP-A No. 2005-251351.

[0066] ε-iron oxide powder A preferred 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 an ε-iron oxide crystalline structure is detected as the main phase by X-ray diffraction analysis. For example, if the highest intensity diffraction peak in an X-ray diffraction spectrum obtained by X-ray diffraction analysis is assigned to the ε-iron oxide crystalline structure, it is determined that the ε-iron oxide crystalline structure is detected as the main phase. Known methods for producing ε-iron oxide powder include a method using goethite and a reverse micelle method. All of these production methods are publicly known. For a method for producing ε-iron oxide powder in which part of the Fe atoms are replaced by atoms such as Ga, Co, Ti, Al, or Rh, see, for example, J. Jpn. Soc. Powder Metallurgy, Vol. 61, Supplement, No. S1, pp. S280-S284 and J. Mater. Chem. C, 2013, 1, pp. 5200-5206. However, the method for producing the ε-iron oxide powder that can be used as the ferromagnetic powder in the magnetic layer of the data tape is not limited to the method given here.

[0067] The activation volume of the ε-iron oxide powder is preferably 300 to 1500 nm 3 The microparticulated ε-iron oxide powder exhibiting an activation volume in the above range is suitable for producing a data tape that exhibits excellent electromagnetic conversion characteristics. The activation volume of the ε-iron oxide powder is preferably 300 nm 3or more, for example, 500 nm 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 1100 nm or less. 3 It is even more preferred that:

[0068] 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 and more preferably 8.0×10 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 therefore preferred, the Ku value is not limited to the above-mentioned values.

[0069] From the viewpoint of increasing the reproduction output when reproducing data recorded on a data tape, it is desirable that the mass magnetization σs of the ferromagnetic powder contained in the data 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 can be 40 A m 2 / kg or less, and 35A·m 2 / kg or less is more preferable.

[0070] 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 using a transmission electron microscope at a magnification of 100,000x, and the photograph is printed on photographic paper or displayed on a display so that the total magnification is 500,000x, to obtain a particle photograph of the particles that make up the powder. From the obtained particle photograph, the target particle is selected, and the particle outline is traced with a digitizer to measure the particle (primary particle) size. Primary particles are independent particles that are not aggregated. The above measurements are performed on 500 randomly selected particles. The arithmetic mean of the particle sizes of the 500 particles thus obtained is defined as the average particle size of the powder. The transmission electron microscope may be, for example, a Hitachi H-9000 transmission electron microscope. Furthermore, particle size measurements can be performed using known image analysis software, such as Carl Zeiss KS-400 image analysis software. Unless otherwise specified, the average particle sizes described in the Examples section below are values ​​measured using a Hitachi H-9000 transmission electron microscope and Carl Zeiss KS-400 image analysis software. In this invention and this specification, "powder" refers to a collection of multiple particles. For example, "ferromagnetic powder" refers to a collection of multiple ferromagnetic particles. Furthermore, a collection of multiple particles is not limited to a configuration in which the particles constituting the collection are in direct contact with each other, but also includes a configuration in which binders, additives, etc., as described below, are interposed between the particles. The term "particle" is sometimes used to refer to powder.

[0071] As a method for collecting sample powder from a data tape for particle size measurement, for example, the method described in paragraph 0015 of JP-A No. 2011-048878 can be used.

[0072] In the present invention and this specification, with regard to particle shape, "plate-like" refers to a shape having two opposing plate surfaces. "Plate surface" refers to the plane observed on the surface of the particle in the particle photograph above and the plane opposite to that plane. On the other hand, among particle shapes that do not have such plate surfaces, shapes with a distinct major and minor axis are "elliptical." The major axis is determined as the axis (straight line) along which the particle length can be measured. On the other hand, the minor axis is determined as the axis with the longest length when the particle length is measured along a straight line perpendicular to the major axis. A shape in which there is no distinction between the major and minor axes, i.e., a shape in which the major axis length = the minor axis length, is "spherical." A shape in which the major and minor axes cannot be identified from the shape is called amorphous. In the present invention and this specification, unless otherwise specified, the size of particles constituting the powder (particle size) refers to the plate diameter if the particle shape observed in the particle photograph is plate-like, the major axis length if the particle shape is elliptical, the diameter if the particle shape is spherical, and the equivalent circle diameter if the particle shape is irregular. The equivalent circle diameter is determined by the circle projection method.

[0073] For plate-like particles, the "plate thickness" is the longest distance between two opposing plate surfaces, and the average plate thickness is the arithmetic mean of the values ​​obtained for the above 500 particles.

[0074] 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.

[0075] (binder) The data tape may be a coated magnetic tape, and the magnetic layer may contain a binder. The binder is one or more resins. Various resins commonly used as binders for coated magnetic tapes can be used. For example, the binder may be 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., and may be used alone or in combination. 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 nonmagnetic layer and / or backcoat layer, which will be described later. For details of the binders described above, see 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 or more and 200,000 or less in weight average molecular weight. The binder can be used in an amount of, for example, 1.0 to 30.0 parts by mass per 100.0 parts by mass of the ferromagnetic powder.

[0076] (hardening agent) A curing agent can also be used together with a resin usable as a binder. In one form, the curing agent can be a thermosetting compound, which undergoes a curing reaction (crosslinking reaction) upon heating. In another form, the curing agent can be a photocurable compound, which undergoes a curing reaction (crosslinking reaction) upon irradiation with light. As the curing reaction progresses during the magnetic layer-forming process, at least a portion of the curing agent can be included in the magnetic layer in a state of reaction (crosslinking) with other components, such as the binder. This also applies to layers formed using compositions containing a curing agent when the composition used to form other layers contains the curing agent. A preferred curing agent is a thermosetting compound, and polyisocyanate is suitable. For details about polyisocyanates, see paragraphs 0124-0125 of JP 2011-216149 A. The curing agent can be used in the magnetic layer-forming composition in an amount of, for example, 0 to 80 parts by weight per 100 parts by weight of the binder. From the perspective of improving the strength of the magnetic layer, 50 to 80 parts by weight is preferred.

[0077] (additives) The magnetic layer may contain one or more additives as needed. Commercially available additives can be selected and used depending on the desired properties. Alternatively, compounds synthesized by known methods can be used as additives. Additives can be used in any amount. Examples of additives include the curing agents described above. Examples of additives contained in the magnetic layer include nonmagnetic powders, lubricants, dispersants, dispersion aids, antifungal agents, antistatic agents, and antioxidants. For lubricants, see paragraphs 0030 to 0033, 0035, and 0036 of JP 2016-126817 A. The nonmagnetic layer described below may contain a lubricant. For lubricants that can be contained in the nonmagnetic layer, see paragraphs 0030 to 0031, 0034, 0035, and 0036 of JP 2016-126817 A. For dispersants, see paragraphs 0061 and 0071 of JP 2012-133837 A. A dispersant may be added to the nonmagnetic layer-forming composition. For dispersants that can be added to the nonmagnetic layer-forming composition, see paragraph 0061 of JP-A No. 2012-133837.

[0078] Regarding the Spc and width-direction σ of the Spc on the magnetic layer surface, the inventors' investigations revealed that it is preferable for the magnetic layer to contain nonmagnetic powder composed of plate-like particles, from the viewpoint of controlling the Spc and width-direction σ of the Spc on the magnetic layer surface within the ranges described above. Furthermore, from the viewpoint of controlling the Spc and width-direction σ of the Spc on the magnetic layer surface within the ranges described above, the inventors' investigations also revealed that it is more preferable for the magnetic layer to contain nonmagnetic powder with an average plate diameter of 50 nm to 1000 nm and an average plate thickness of 12 nm or less. The average plate thickness can be, for example, 3 nm or more, 4 nm or more, or 5 nm or more, and can also be less than the values ​​exemplified here. The nonmagnetic powder composed of plate-like particles (preferably a nonmagnetic powder with an average plate diameter of 50 nm to 1000 nm and an average plate thickness of 12 nm or less) can be, for example, a metal oxide powder. Specific examples of metal oxides include aluminum oxide, zirconium oxide, and cerium oxide. Aluminum oxide is also called alumina, zirconium oxide is also called zirconia, and cerium oxide is also called ceria. For example, plate-shaped metal oxide particles can be obtained by heating an aqueous solution of a metal hydroxide to a liquid temperature of 200°C or higher to cause a hydrothermal synthesis reaction. The plate diameter and plate thickness of the plate-shaped particles can be controlled by adjusting various conditions for particle preparation (e.g., concentration of the aqueous solution, mixing time during preparation of the aqueous solution, heating temperature, heating time, etc.). The content of the nonmagnetic powder in the magnetic layer can be, for example, 0.02 to 0.80 parts by mass per 100.00 parts by mass of the ferromagnetic powder.

[0079] Non-magnetic powders that can be contained in the magnetic layer include non-magnetic powders that can function as abrasives. For example, see paragraphs 0030 to 0032 of Japanese Patent Application Laid-Open No. 2004-273070 for abrasives. Examples of abrasives include those with a specific surface area measured by the BET (Brunauer-Emmett-Teller) method (hereinafter referred to as "BET specific surface area") of 14 m. 2 From the viewpoint of dispersibility, it is preferable to use an abrasive having a BET specific surface area of ​​40 m2 It is preferable to use an abrasive having a particle size of 0.1 / g or less.

[0080] As the abrasive, a non-magnetic powder with a Mohs hardness of greater than 8 is preferred, and a non-magnetic powder with a Mohs hardness of 9 or higher is more preferred. The maximum Mohs hardness is 10. The abrasive can be a powder of an inorganic substance or a powder of an organic substance. The abrasive can be a powder of an inorganic or organic oxide or carbide. Examples of carbides include boron carbide (e.g., BC) and titanium carbide (e.g., TiC). Diamond can also be used as the abrasive. In one form, the abrasive is preferably a powder of an inorganic oxide. Specific examples of inorganic oxides include aluminum oxide (alumina), titanium oxide, cerium oxide (ceria), and zirconium oxide (zirconia), with alumina being preferred. The Mohs hardness of alumina is approximately 9. For alumina powder that can be used as an abrasive, see paragraph 0021 of JP 2013-229090 A. The content of the abrasive in the magnetic layer is preferably 0.02 to 0.80 parts by mass per 100.00 parts by mass of the ferromagnetic powder. Only one type of nonmagnetic powder can be used as the abrasive, or two or more types of nonmagnetic powders with different compositions and / or physical properties (e.g., size) can also be used. When two or more types of nonmagnetic powders are used as the abrasive, the content of the abrasive refers to the total content of those two or more nonmagnetic powders. The same applies to the content of various components in this invention and this specification. The abrasive is preferably subjected to a dispersion treatment separately from the ferromagnetic powder (separate dispersion), and more preferably subjected to a dispersion treatment separately from the nonmagnetic powder described above (separate dispersion). When preparing the magnetic layer-forming composition, two or more dispersions with different components and / or dispersion conditions can also be prepared as a dispersion of the abrasive (hereinafter also referred to as "abrasive liquid").

[0081] A dispersant can also be used to adjust the dispersion state of the abrasive liquid. Compounds that can function as dispersants to improve the dispersibility of abrasives include aromatic hydrocarbon compounds having a phenolic hydroxy group. A "phenolic hydroxy group" refers to a hydroxy group directly bonded to an aromatic ring. The aromatic ring contained in the aromatic hydrocarbon compound may be a monocyclic ring, a polycyclic structure, or a fused ring. From the perspective of improving the dispersibility of abrasives, aromatic hydrocarbon compounds containing a benzene ring or a naphthalene ring are preferred. The aromatic hydrocarbon compound may also have a substituent other than the phenolic hydroxy group. Examples of the substituent other than the phenolic hydroxy group include a halogen atom, an alkyl group, an alkoxy group, an amino group, an acyl group, a nitro group, a nitroso group, and a hydroxyalkyl group. A halogen atom, an alkyl group, an alkoxy group, an amino group, and a hydroxyalkyl group are preferred. The number of phenolic hydroxy groups contained in one molecule of the aromatic hydrocarbon compound may be one, two, three, or more.

[0082] A preferred embodiment of the aromatic hydrocarbon compound having a phenolic hydroxy group is a compound represented by the following formula 100.

[0083] [ka] [In formula 100, X 101 ~X 108 Two of the groups are hydroxy groups, and the other six groups each independently represent a hydrogen atom or a substituent.

[0084] In the compound represented by formula 100, the substitution positions of the two hydroxy groups (phenolic hydroxy groups) are not particularly limited.

[0085] The compound of formula 100 is X 101 ~X 108Two of the X's are hydroxy groups (phenolic hydroxy groups), and the other six each independently represent a hydrogen atom or a substituent. 101 ~X 108 In the above, all the moieties other than the two hydroxyl groups may be hydrogen atoms, or some or all may be substituents. Examples of the substituents include the substituents described above. One or more phenolic hydroxyl groups may be included as the substituents other than the two hydroxyl groups. From the viewpoint of improving the dispersibility of the abrasive, X 101 ~X 108 Preferably, the two hydroxy groups other than the two hydroxy groups are not phenolic hydroxy groups. That is, the compound represented by formula 100 is preferably dihydroxynaphthalene or a derivative thereof, more preferably 2,3-dihydroxynaphthalene or a derivative thereof. 101 ~X 108 Preferred examples of the substituent represented by the formula (I) include a halogen atom (for example, a chlorine atom or a bromine atom), an amino group, an alkyl group having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms), a methoxy group, an ethoxy group, an acyl group, a nitro group, a nitroso group, and a —CHOH group.

[0086] Furthermore, for dispersants for improving the dispersibility of abrasives, reference can also be made to paragraphs 0024 to 0028 of JP 2014-179149 A.

[0087] A dispersant for improving the dispersibility of an abrasive can be used, for example, when preparing an abrasive liquid, in a proportion of, for example, 0.5 to 20.0 parts by mass per 100.0 parts by mass of the abrasive, and is preferably used in a proportion of 1.0 to 10.0 parts by mass.

[0088] One type of additive that can be contained in the magnetic layer is a compound having an ammonium salt structure of an alkyl ester anion, as represented by the following formula 1.

[0089] [ka]

[0090] (In formula 1, R represents an alkyl group having 7 or more carbon atoms or a fluorinated alkyl group having 7 or more carbon atoms, and Z + represents an ammonium cation.)

[0091] The inventors believe that the above compounds may function as lubricants, as will be further explained below. Lubricants can be broadly divided into fluid lubricants and boundary lubricants. The inventors believe that compounds having an ammonium salt structure of an alkyl ester anion, as represented by the above formula 1, can function as fluid lubricants. It is believed that fluid lubricants themselves can form a liquid film on the surface of the magnetic layer, thereby providing lubrication to the magnetic layer. F 10° In order to control the frictional force (leader pin attachment end region), it is presumed that it is desirable for the fluid lubricant to form a liquid film on the magnetic layer surface. Also, the more stable the sliding between the magnetic layer surface and the LTO9 head during frictional force measurement, the greater the F 10° The value of (leader pin attachment end region) can be smaller. Regarding the liquid film of the fluid lubricant, from the viewpoint of enabling more stable sliding, it is considered desirable to use an appropriate amount of fluid lubricant forming a liquid film on the magnetic layer surface. This is because if the amount of liquid lubricant forming the liquid film on the magnetic layer surface is excessive, it is thought that the magnetic layer surface and the LTO9 head will stick together, making sliding stability more likely to decrease. Furthermore, if the amount of liquid lubricant forming the liquid film on the magnetic layer surface is excessive, it is thought that protrusions formed on the magnetic layer surface by, for example, non-magnetic filler will be covered by the liquid film. This is also thought to be a factor that makes sliding stability more likely to decrease. In this regard, the compound contains an ammonium salt structure of an alkyl ester anion represented by Formula 1. It is believed that a compound containing such a structure can play an excellent role as a fluid lubricant even in a relatively small amount. Therefore, the inclusion of the compound in the magnetic layer leads to an improvement in the sliding stability between the magnetic layer surface of the magnetic tape and the LTO9 head, and F 10° It is believed that this can contribute to controlling the area of ​​the end portion of the leader pin.

[0092] The above compounds will be described in more detail below.

[0093] In the present invention and this specification, unless otherwise specified, the groups described may have a substituent or may be unsubstituted. Furthermore, with respect to a group having a substituent, the "number of carbon atoms" refers to the number of carbon atoms excluding the number of carbon atoms of the substituent, unless otherwise specified. In the present invention and this specification, examples of the substituent include an alkyl group (e.g., an alkyl group having 1 to 6 carbon atoms), a hydroxy group, an alkoxy group (e.g., an alkoxy group having 1 to 6 carbon atoms), a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, etc.), a cyano group, an amino group, a nitro group, an acyl group, a carboxy group, a salt of a carboxy group, a sulfonic acid group, a salt of a sulfonic acid group, etc.

[0094] At least a portion of the compound having the ammonium salt structure of the alkyl ester anion represented by Formula 1 contained in the magnetic layer can form a liquid film on the surface of the magnetic layer, and a portion can be contained within the magnetic layer and migrate to the surface of the magnetic layer during sliding contact with the magnetic head, forming a liquid film. Furthermore, a portion can be contained in the non-magnetic layer described below, and can migrate to the magnetic layer and then to the surface of the magnetic layer to form a liquid film. The "alkyl ester anion" can also be called an "alkyl carboxylate anion."

[0095] In formula 1, R represents an alkyl group having 7 or more carbon atoms or a fluorinated alkyl group having 7 or more carbon atoms. The fluorinated alkyl group has a structure in which some or all of the hydrogen atoms constituting the alkyl group are substituted with fluorine atoms. The alkyl group or fluorinated alkyl group represented by R may have a linear structure, a branched structure, or a cyclic alkyl group or fluorinated alkyl group, and preferably has a linear structure. The alkyl group or fluorinated alkyl group represented by R may have a substituent or may be unsubstituted, and is preferably unsubstituted. The alkyl group represented by R is, for example, C n H 2n+1-, where n is an integer of 7 or more. The fluorinated alkyl group represented by R can be, for example, C n H 2n+1 The alkyl group or fluorinated alkyl group represented by R may have a structure in which some or all of the hydrogen atoms constituting the alkyl group represented by R are substituted with fluorine atoms. The number of carbon atoms in the alkyl group or fluorinated alkyl group represented by R is 7 or more, preferably 8 or more, more preferably 9 or more, even more preferably 10 or more, still more preferably 11 or more, even more preferably 12 or more, and still more preferably 13 or more. The number of carbon atoms in the alkyl group or fluorinated alkyl group represented by R is preferably 20 or less, more preferably 19 or less, and even more preferably 18 or less.

[0096] In equation 1, Z + represents an ammonium cation. Specifically, the ammonium cation has the following structure: In the present invention and this specification, "*" in a formula representing a part of a compound represents the bonding position between the part of the structure and the adjacent atom.

[0097] [ka]

[0098] Nitrogen cation N of ammonium cation + and the oxygen anion O in Eq. - and form a salt bridging group to form an ammonium salt structure of an alkyl ester anion represented by formula 1. The presence of a compound having an ammonium salt structure of an alkyl ester anion represented by formula 1 in the magnetic layer can be confirmed by analyzing the magnetic tape using X-ray photoelectron spectroscopy (ESCA: Electron Spectroscopy for Chemical Analysis), infrared spectroscopy (IR: infrared spectroscopy), etc.

[0099] In one form, Z +The ammonium cation represented by the formula (I) can be obtained, for example, by converting a nitrogen atom of a nitrogen-containing polymer into a cation. A nitrogen-containing polymer refers to a polymer containing nitrogen atoms. In the present invention and this specification, the terms "polymer" and "polymeric polymer" are used to encompass homopolymers and copolymers. In one form, the nitrogen atom can be included as an atom constituting the main chain of the polymer, or in another form, as an atom constituting the side chain of the polymer.

[0100] One example of the nitrogen-containing polymer is polyalkyleneimine, which is a ring-opening polymer of alkyleneimine and has a plurality of repeating units represented by the following formula 2.

[0101] [ka]

[0102] The nitrogen atom N constituting the main chain in formula 2 is a nitrogen cation N + So Z in Equation 1 + This can result in an ammonium cation represented by the formula: and can form an ammonium salt structure with an alkyl ester anion, for example, as follows:

[0103] [ka]

[0104] Equation 2 will be explained in more detail below.

[0105] In formula 2, R 1 and R 2 each independently represents a hydrogen atom or an alkyl group, and n1 represents an integer of 2 or more.

[0106] R 1 or R 2Examples of the alkyl group represented by R include alkyl groups having 1 to 6 carbon atoms, preferably alkyl groups having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. 1 or R 2 The alkyl group represented by the formula (2) is preferably an unsubstituted alkyl group. 1 and R 2 The combinations include one in which one is a hydrogen atom and the other is an alkyl group, both in which hydrogen atoms are present, and both in which alkyl groups (the same or different alkyl groups) are present, with both in which hydrogen atoms are preferred. The alkyleneimine that yields the polyalkyleneimine has the smallest number of carbon atoms in the ring, which is ethyleneimine, and the alkyleneimine (ethyleneimine) obtained by ring-opening the ethyleneimine has two carbon atoms in its main chain. Therefore, n1 in Formula 2 is 2 or more. n1 in Formula 2 can be, for example, 10 or less, 8 or less, 6 or less, or 4 or less. The polyalkyleneimine may be a homopolymer containing only the same repeating structure represented by Formula 2, or a copolymer containing two or more different repeating structures represented by Formula 2. The number-average molecular weight of the polyalkyleneimine that can be used to form a compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 can be, for example, 200 or more, preferably 300 or more, and more preferably 400 or more. The number average molecular weight of the polyalkyleneimine can be, for example, 10,000 or less, preferably 5,000 or less, and more preferably 2,000 or less.

[0107] In the present invention and this specification, the average molecular weight (weight average molecular weight and number average molecular weight) refers to a value measured by gel permeation chromatography (GPC) and calculated in terms of standard polystyrene. Unless otherwise specified, the average molecular weight shown in the Examples section below is a value (polystyrene-equivalent value) calculated in terms of standard polystyrene from a value measured using GPC under the following measurement conditions: GPC equipment: HLC-8220 (Tosoh Corporation) Guard column: TSKguardcolumn Super HZM-H Columns: TSKgel Super HZ 2000, TSKgel Super HZ 4000, TSKgel Super HZ-M (Tosoh Corporation, 4.6 mm (inner diameter) x 15.0 cm, three columns connected in series) Eluent: tetrahydrofuran (THF), containing stabilizer (2,6-di-t-butyl-4-methylphenol) Eluent flow rate: 0.35mL / min Column temperature: 40℃ Inlet temperature: 40℃ Refractive Index (RI) measurement temperature: 40℃ Sample concentration: 0.3% by mass Sample injection volume: 10 μL

[0108] Another example of the nitrogen-containing polymer is polyallylamine, which is a polymer of allylamine and has a plurality of repeating units represented by the following formula 3:

[0109] [ka]

[0110] The nitrogen atom N constituting the amino group in the side chain in formula 3 is a nitrogen cation N + So Z in Equation 1 + This can result in an ammonium cation represented by the formula: and can form an ammonium salt structure with an alkyl ester anion, for example, as follows:

[0111] [ka]

[0112] The weight-average molecular weight of polyallylamine that can be used to form a compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 can be, for example, 200 or more, preferably 1,000 or more, and more preferably 1,500 or more. The weight-average molecular weight of the polyallylamine can be, for example, 15,000 or less, preferably 10,000 or less, and more preferably 8,000 or less.

[0113] The fact that the compound having an ammonium salt structure of an alkyl ester anion represented by formula 1 includes a compound having a structure derived from polyalkyleneimine or polyallylamine can be confirmed by analyzing the surface of the magnetic layer using time-of-flight secondary ion mass spectrometry (TOF-SIMS) or the like.

[0114] The compound having the ammonium salt structure of an alkyl ester anion represented by Formula 1 can be a salt of a nitrogen-containing polymer and one or more fatty acids selected from the group consisting of fatty acids having 7 or more carbon atoms and fluorinated fatty acids having 7 or more carbon atoms. The nitrogen-containing polymer that forms the salt can be one or more nitrogen-containing polymers, such as a nitrogen-containing polymer selected from the group consisting of polyalkyleneimines and polyallylamines. The fatty acids that form the salt can be one or more fatty acids selected from the group consisting of fatty acids having 7 or more carbon atoms and fluorinated fatty acids having 7 or more carbon atoms. Fluorinated fatty acids have a structure in which some or all of the hydrogen atoms constituting the alkyl group bonded to the carboxyl group COOH in the fatty acid are substituted with fluorine atoms. For example, the salt-forming reaction can easily proceed by mixing the nitrogen-containing polymer and the fatty acid at room temperature. Room temperature is, for example, about 20 to 25°C. In one embodiment, the salt-forming reaction can proceed by using one or more nitrogen-containing polymers and one or more fatty acids as components of the magnetic layer-forming composition and mixing them in the preparation process of the magnetic layer-forming composition. In one embodiment, prior to preparing the magnetic layer-forming composition, one or more nitrogen-containing polymers and one or more fatty acids are mixed to form a salt, and then this salt is used as a component of the magnetic layer-forming composition to prepare the magnetic layer-forming composition. This also applies to forming a non-magnetic layer containing a compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1. For example, for the magnetic layer, 0.1 to 10.0 parts by weight of the nitrogen-containing polymer can be used per 100.0 parts by weight of ferromagnetic powder, with 0.5 to 8.0 parts by weight being preferred. The fatty acids can be used in an amount of, for example, 0.05 to 10.0 parts by weight, with 0.1 to 5.0 parts by weight being preferred, per 100.0 parts by weight of ferromagnetic powder. For the non-magnetic layer, 0.1 to 10.0 parts by weight of the nitrogen-containing polymer can be used per 100.0 parts by weight of non-magnetic powder, with 0.5 to 8.0 parts by weight being preferred.The fatty acids can be used in an amount of, for example, 0.05 to 10.0 parts by mass, and preferably 0.1 to 5.0 parts by mass, per 100.0 parts by mass of the non-magnetic powder. When the nitrogen-containing polymer and the fatty acids are mixed to form the ammonium salt of the alkyl ester anion represented by formula 1, the nitrogen atoms constituting the nitrogen-containing polymer may also react with the carboxy groups of the fatty acids to form the following structure, and forms containing such structures are also encompassed in the above-mentioned compounds.

[0115] [ka]

[0116] Examples of the fatty acids include fatty acids having an alkyl group as described above for R in Formula 1 and fluorinated fatty acids having a fluorinated alkyl group as described above for R in Formula 1.

[0117] The mixing ratio of the nitrogen-containing polymer and the fatty acids used to form the compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 is preferably 10:90 to 90:10, more preferably 20:80 to 85:15, and even more preferably 30:70 to 80:20, in terms of the mass ratio of nitrogen-containing polymer to fatty acids. Furthermore, the compound having an ammonium salt structure of an alkyl ester anion represented by Formula 1 is preferably contained in the magnetic layer in an amount of 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100.0 parts by mass of ferromagnetic powder. Here, the content of the compound in the magnetic layer refers to the total amount of the compound forming a liquid film on the surface of the magnetic layer and the amount contained within the magnetic layer. On the other hand, a high content of ferromagnetic powder in the magnetic layer is preferable from the perspective of high-density recording. Therefore, from the perspective of high-density recording, a low content of components other than the ferromagnetic powder is preferable. From this viewpoint, the content of the above compounds in the magnetic layer is preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, and even more preferably 8.0 parts by mass or less, per 100.0 parts by mass of the ferromagnetic powder. The same applies to the preferred range of the content of the above compounds in the magnetic layer-forming composition used to form the magnetic layer.

[0118] The magnetic layer described above can be provided directly on the surface of the non-magnetic support, or indirectly via a non-magnetic layer.

[0119] <<Nonmagnetic layer>> Next, the nonmagnetic layer will be described. The data tape may have a magnetic layer directly on the nonmagnetic support, or may have a nonmagnetic layer containing nonmagnetic powder between the nonmagnetic support and the magnetic layer. The nonmagnetic powder used in the nonmagnetic layer may be an inorganic powder (inorganic powder) or an organic powder (organic powder). Carbon black, etc., can also be used. Examples of inorganic substances include metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, and metal sulfides. These nonmagnetic powders are commercially available or can be produced by known methods. For details, see paragraphs 0146 to 0150 of JP 2011-216149 A. For carbon black usable in the nonmagnetic layer, see paragraphs 0040 to 0041 of JP 2010-24113 A. The content (filling rate) of the non-magnetic powder in the non-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 non-magnetic layer.

[0120] In one embodiment, the non-magnetic layer may contain an Fe-based inorganic oxide powder as the non-magnetic powder. In the present invention and this specification, "Fe-based inorganic oxide powder" refers to an inorganic oxide powder containing iron as a constituent element. Specific examples of Fe-based inorganic oxide powder include α-iron oxide powder and goethite powder. In the present invention and this specification, "α-iron oxide powder" refers to a non-magnetic powder in which an α-iron oxide crystal structure is detected as the main phase by X-ray diffraction analysis. α-iron oxide powder is also commonly called hematite.

[0121] From the viewpoint of controlling the width direction σ of Spc within the range described above, the non-magnetic powder for the non-magnetic layer is selected to have an average particle volume of 2.0×10 -6 μm 3 As a result of investigations by the present inventors, it has become clear that it is preferable to use the following Fe-based inorganic oxide powder: Therefore, the average particle volume of the Fe-based inorganic oxide powder contained in the non-magnetic layer is 2.0×10 -6 μm 3 Preferably, it is 1.5 x 10 or less. -6 μm3 More preferably, it is 1.0×10 or less. -6 μm 3 The average particle volume is preferably 1.0×10 or less. -9 μm 3 or more than 1.0×10 -8 μm 3 It can be greater than or less than the values ​​exemplified here.

[0122] In the present invention and this specification, the above average particle volume is a value determined by the following method. To observe the Fe-based inorganic oxide powder contained in the nonmagnetic layer of the data tape, the sample is first pretreated by microtoming. The sectioning is performed along the longitudinal direction of the data tape to obtain a thin section sample that allows for observation of the cross section in the thickness direction of the data tape. For each of the examples, comparative examples, and reference examples described below, a thin section sample was obtained from one of the prepared data tapes using a Leica EM UC6 microtome manufactured by Leica. The obtained thin film sample was observed using a transmission electron microscope (TEM) at an acceleration voltage of 300 kV and a total magnification of 200,000 times, so as to include the area from the non-magnetic support to the magnetic layer, and a cross-sectional TEM image was obtained. As the transmission electron microscope, for example, a JEOL JEM-2100Plus can be used. In the examples, comparative examples, and reference examples described below, a JEOL JEM-2100Plus was used as the transmission electron microscope. In the obtained cross-sectional TEM image, 50 particles of the Fe-based inorganic oxide powder are identified from the particles contained in the nonmagnetic layer using a micro-electron diffraction method. Electron diffraction by the micro-electron diffraction method is performed using a transmission electron microscope at an acceleration voltage of 200 kV and a camera length of 50 cm. In the examples, comparative examples, and reference examples described below, a JEOL JEM-2100Plus transmission electron microscope was used for electron diffraction by the micro-electron diffraction method. Thereafter, using 50 particles of the Fe-based inorganic oxide powder identified as above, the average particle volume is determined as follows. First, the major axis length (hereinafter also referred to as "DL") and minor axis length (hereinafter also referred to as "DS") of each particle are measured. The major axis length DL means the maximum distance between two parallel lines drawn at any angle so as to be tangent to the outline of the particle (the so-called maximum Feret's diameter). If the direction of the major axis length defined above is called the major axis direction, the minor axis length DS means the maximum length of the particle in the direction perpendicular to the major axis direction of the particle. Next, the average major axis length DLave is calculated as the arithmetic mean of the major axis lengths DL of the measured 50 particles. Ave is an abbreviation for average. In addition, the average minor axis length DSave is calculated as the arithmetic mean of the minor axis lengths DS of the above 50 particles. The average particle volume Vave is calculated from the average major axis length DLave and the average minor axis length DSave using the following formula. Vave = π / 6 × DSave 2 ×DLave

[0123] In one embodiment, the non-magnetic layer may also contain carbon black as the non-magnetic powder. The average particle size of the carbon black may be, for example, 10 nm or more and 50 nm or less. From the viewpoint of controlling the width direction σ of Spc within the range described above, the inventors' investigations have revealed that it is preferable to use carbon black with a pH of 9.0 or less as the non-magnetic powder in the non-magnetic layer. Therefore, the pH of the carbon black contained in the non-magnetic layer is preferably 9.0 or less, more preferably 8.5 or less, even more preferably 8.0 or less, and even more preferably 7.5 or less. The pH may be, for example, 1.0 or more, 2.0 or more, 3.0 or more, 4.0 or more, 5.0 or more, or 6.0 or more, or may be lower than the values ​​exemplified herein.

[0124] In the present invention and in this specification, the pH of carbon black is the value measured in accordance with standard test method ASTM D1512.

[0125] The non-magnetic layer has an average grain volume of 2.0 × 10 -6 μm 3 It is preferable to include at least one of the following Fe-based inorganic oxide powder and carbon black having a pH of 9.0 or less, and more preferable to include both: an average particle volume of 2.0×10 relative to 100.0 parts by mass of the total amount of non-magnetic powder contained in the non-magnetic layer; -6 μm 3 The content of the Fe-based inorganic oxide powder described below can be 50.0 parts by mass or more, 60.0 parts by mass or more, or 70.0 parts by mass or more, and can be, for example, 90.0 parts by mass or less. The content of carbon black having a pH of 9.0 or less, relative to 100.0 parts by mass of the total amount of non-magnetic powder contained in the non-magnetic layer, can be 10.0 parts by mass or more, or 20.0 parts by mass or more, and can be, for example, 50.0 parts by mass or less, 40.0 parts by mass or less, or 30.0 parts by mass or less.

[0126] The non-magnetic layer may contain a binder and may also contain additives. For other details of the binder, additives, etc. of the non-magnetic layer, known techniques related to non-magnetic layers can be applied. Furthermore, 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.

[0127] The non-magnetic layer of the data tape also includes a substantially non-magnetic layer that contains a small amount of ferromagnetic powder, either as an impurity or intentionally, along with the non-magnetic powder. Here, a substantially non-magnetic 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 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 non-magnetic layer have no residual magnetic flux density or coercive force.

[0128] <<Nonmagnetic support>> Next, the non-magnetic support will be described. Examples of the non-magnetic support (hereinafter also simply referred to as "support") include known biaxially stretched polyethylene terephthalate, polyethylene naphthalate, polyamide, polyamideimide, aromatic polyamide, etc. Among these, polyethylene terephthalate, polyethylene naphthalate, and polyamide are preferred. These supports may be previously subjected to corona discharge, plasma treatment, easy-adhesion treatment, heat treatment, etc.

[0129] <<Backcoat layer>> The data tape may or may not have a backcoat layer containing nonmagnetic powder on the surface of the nonmagnetic support opposite the surface having the magnetic layer. The backcoat layer preferably contains one or both of carbon black and inorganic powder. The backcoat layer may also contain a binder and additives. For details of the nonmagnetic powder, binder, additives, etc., of the backcoat layer, known techniques related to backcoat layers can be applied, as can known techniques related to magnetic and / or nonmagnetic layers. For example, see paragraphs

[0018] to

[0020] of Japanese Patent Laid-Open No. 2006-331625 and U.S. Patent No. 7,029,774, column 4, line 65 to column 5, line 38, for information regarding backcoat layers.

[0130] <<Various thicknesses>> With regard to the thickness (total thickness) of data tapes, the enormous increase in the amount of information in recent years has led to a demand for increased recording capacity (higher capacity) for magnetic recording media. For tape-type magnetic recording media (i.e., data tapes), one way to increase the capacity is to reduce the thickness of the data tape and increase the length of magnetic tape accommodated in one magnetic tape cartridge. From this perspective, the thickness (total thickness) of the data tape is preferably 5.6 μm or less, more preferably 5.5 μm or less, even more preferably 5.4 μm or less, even more preferably 5.3 μm or less, even more preferably 5.2 μm or less, even more preferably 5.0 μm or less, and even more preferably 4.8 μm or less. Furthermore, from the perspective of ease of handling, the thickness of the data tape is preferably 3.0 μm or more, more preferably 3.5 μm or more, and even more preferably 4.0 μm or more. The thickness (total thickness) of the data tape can be measured by the following method. Ten tape samples (e.g., 5 to 10 cm long) are cut from any portion of the data tape, and these tape samples are stacked and measured for thickness. The measured thickness is divided by 10 to obtain the value (thickness per tape sample), which is taken as 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.

[0131] 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 of the magnetic head used, the head gap length, the bandwidth of the recording signal, etc., and is generally 0.01 μm to 0.15 μm, and from the viewpoint of high-density recording, it 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 with different magnetic properties, and known configurations related to multilayer magnetic layers can be applied. When the magnetic layer is separated into two or more layers, the thickness of the magnetic layer refers to the total thickness of these layers. The thickness of the non-magnetic layer is, for example, 0.1 to 1.5 μm, preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0.7 μm. The thickness of the backcoat layer is preferably 0.9 μm or less, and more preferably 0.1 to 0.7 μm. The thickness of the magnetic layer and other thicknesses can be determined by the following method. After exposing a cross section of the data tape in the thickness direction with an ion beam, the exposed cross section is observed using a scanning electron microscope or a transmission electron microscope. The thicknesses can be calculated as the arithmetic mean of the thicknesses measured at any two points during the cross section observation. Alternatively, the thicknesses can be calculated as the design thickness calculated from the manufacturing conditions, etc.

[0132] <<Manufacturing process>> (Preparation of compositions for forming each layer) Compositions for forming the magnetic layer, nonmagnetic layer, or backcoat layer typically contain a solvent in addition to the various components described above. The solvent can be one or more of the various solvents commonly used in the production of particulate magnetic recording media. The solvent content of each layer-forming composition is not particularly limited. For details about solvents, see paragraph 0153 of JP 2011-216149 A. The solids concentration and solvent composition of each layer-forming composition can be adjusted appropriately depending on the composition's handling suitability, coating conditions, and the thickness of each layer to be formed. The process for preparing a composition for forming the magnetic layer, nonmagnetic layer, or backcoat layer typically includes at least a kneading step, a dispersion step, and optionally, a mixing step before or after these steps. Each individual step may be divided into two or more stages. The various components used in preparing each layer-forming composition may be added at the beginning or during any step. Alternatively, individual components may be added in separate steps in two or more steps. For example, the binder may be added in separate steps in the kneading step, the dispersion step, and the mixing step for adjusting the viscosity after dispersion. The manufacturing process for the data tape described above can employ some conventional manufacturing techniques. For the kneading process, devices with strong kneading power, such as an open kneader, continuous kneader, pressure kneader, or extruder, can be used. Details of the kneading process are described in Japanese Patent Application Laid-Open Nos. 1-106338 and 1-79274. Various known dispersers utilizing shear force, such as a bead mill, ball mill, sand mill, or homomixer, can be used. Dispersion beads are preferably used for dispersion. Examples of dispersing beads include ceramic beads and glass beads, with zirconia beads being 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 depending on the powder to be dispersed. The dispersion time is not particularly limited. The inventors believe that, from the perspective of controlling the Spc and width-direction σ of the Spc on the magnetic layer surface within the ranges described above, it is preferable to extend the dispersion time in the preparation of the magnetic layer-forming composition. The composition for forming each layer may be filtered by a known method before being subjected to the coating step.The filtration can be carried out, for example, by filter filtration. The filter used for filtration may be, for example, a filter with a pore size of 0.01 to 3 μm (for example, a glass fiber filter, a polypropylene filter, etc.).

[0133] (Coating process, cooling process, heating and drying process) The magnetic layer can be formed by applying the magnetic layer-forming composition directly onto the non-magnetic support, or by sequentially or simultaneously applying the magnetic layer-forming composition and the non-magnetic layer-forming composition in a multilayer manner. For details on the coating for forming each layer, see paragraph 0066 of JP2010-231843A.

[0134] As described above, in one embodiment, the data tape can have a non-magnetic layer between the non-magnetic support and the magnetic layer. Such a data tape can preferably be manufactured by sequential multilayer coating. The manufacturing process using sequential multilayer coating can be preferably carried out as follows: The non-magnetic layer is formed through a coating step in which a non-magnetic layer-forming composition is applied to the non-magnetic support to form a coating layer, and a heat-drying step in which the formed coating layer is dried by heat treatment. The magnetic layer is then formed through a coating step in which a magnetic layer-forming composition is applied to the formed non-magnetic layer to form a coating layer, and a heat-drying step in which the formed coating layer is dried by heat treatment. In one embodiment, in the non-magnetic layer-forming process of the manufacturing method using sequential multilayer coating, a coating layer can be formed by performing a coating step using a non-magnetic layer-forming composition, and a cooling step in which the coating layer is cooled can be performed between the coating step and the heat-drying step.

[0135] An example of the manufacturing process for the data tape will be described below with reference to Figure 10. However, the present invention is not limited to the following example.

[0136] Fig. 10 is a process schematic diagram showing an example of a process for producing a magnetic tape having a nonmagnetic layer and a magnetic layer, in that order, on one side of a nonmagnetic support, and a backcoat layer on the other side. In the example shown in Fig. 10, the nonmagnetic support (long film) is continuously wound from a feed section to a take-up section, and various processes such as coating, drying, and orientation are performed in each section or zone shown in Fig. 10, so that a nonmagnetic layer and a magnetic layer can be formed by sequential multilayer coating on one side of the running nonmagnetic support, and a backcoat layer can be formed on the other side. The example shown in Fig. 10 can be similar to a manufacturing process typically used for producing particulate magnetic recording media, except that it includes a cooling zone.

[0137] The non-magnetic support delivered from the delivery section is coated with a non-magnetic layer forming composition in the first coating section (non-magnetic layer forming composition coating step).

[0138] After the coating step, the coating layer of the nonmagnetic layer-forming composition formed in the coating step is cooled in a cooling zone (cooling step). For example, the cooling step can be performed by passing the nonmagnetic support on which the coating layer has been formed through a cooling atmosphere. The temperature of the cooling atmosphere can preferably be in the range of -10°C to 0°C, and more preferably in the range of -5°C to 0°C. The time for performing the cooling step (for example, the time from when any part of the coating layer is carried into the cooling zone until when it is carried out (hereinafter also referred to as "residence time")) is not particularly limited. In the cooling step, cooled gas may be blown onto the surface of the coating layer.

[0139] After the cooling zone, the coating layer is dried by heating it in the first heat treatment zone (heat drying step). The heat drying step can be performed by passing the non-magnetic support bearing the coating layer after the cooling step through a heated atmosphere. The temperature of the heated atmosphere here, as well as the temperature of the heated atmosphere in the heat drying step in the second heat treatment zone and the heat drying step in the third heat treatment zone described below, are also referred to as the "drying temperature." In one embodiment, the drying temperature in each heat treatment zone is preferably 95°C or higher, more preferably 100°C or higher. The drying temperature in each heat treatment zone can be, for example, 140°C or lower or 130°C or lower, and can also be higher than the temperatures listed here. Optionally, heated gas may be blown onto the surface of the coating layer.

[0140] Next, in the second coating section, a magnetic layer-forming composition is coated onto the non-magnetic layer formed by the heat drying step in the first heat treatment zone (magnetic layer-forming composition coating step).

[0141] In the case of a subsequent orientation treatment, the ferromagnetic powder in the coating layer of the magnetic layer-forming composition is oriented in the orientation zone while the coating layer is still wet. Various known techniques, including those described in paragraph 0067 of JP 2010-231843 A, can be applied to the orientation treatment. For example, vertical orientation treatment can be performed by known methods, 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 of the magnetic tape in the orientation zone. The coating layer may also be pre-dried before being transported to the orientation zone.

[0142] After the orientation treatment, the coated layer is subjected to a heat drying step in the second heat treatment zone.

[0143] Next, in the third coating section, a backcoat layer-forming composition is applied to the surface of the non-magnetic support opposite to the surface on which the non-magnetic layer and the magnetic layer are formed, to form a coating layer (backcoat layer-forming composition application step).Then, in the third heat treatment zone, the coating layer is heat-treated and dried.

[0144] Through the above steps, a magnetic tape can be obtained which has a nonmagnetic layer and a magnetic layer in this order on one side of a nonmagnetic support and a backcoat layer on the other side.

[0145] (Other processes) In the manufacturing process of magnetic tape, calendering is usually performed to improve the surface smoothness of the magnetic tape. Strengthening the calendering conditions can contribute to reducing the value of the width direction σ of Spc. Specific examples of strengthening the calendering conditions include increasing the calendering pressure, increasing the calendering temperature, and reducing the calendering speed. Regarding the calendering conditions, the calendering pressure (linear pressure) is preferably 300 to 500 kN / m, more preferably 310 to 350 kN / m, the calendering temperature (calender roll surface temperature) is preferably 95 to 120°C, more preferably 100 to 120°C, and the calendering speed is preferably 50 to 75 m / min. For other various steps for manufacturing magnetic tape, reference can be made to paragraphs 0067 to 0070 of JP-A-2010-231843. A long magnetic tape raw material can be obtained through various processes. The obtained magnetic tape raw material is cut (slit) using a known cutting machine to the width of the magnetic tape to be housed in a magnetic tape cartridge, for example. The width can be determined according to standards and is usually 1 / 2 inch. 1 inch = 2.54 cm. The width of the reinforcing layer, which will be described later, is also usually 1 / 2 inch. A servo pattern is usually formed on the magnetic tape obtained by slitting.

[0146] (Servo pattern formation) "Forming a servo pattern" can also be called "recording a servo signal." Forming a servo pattern will be explained below.

[0147] The servo pattern is usually 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.

[0148] As specified in ECMA (European Computer Manufacturers Association)-319 (June 2001), magnetic tapes conforming to the LTO (Linear Tape-Open) standard (commonly referred to as "LTO tapes") 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 along the longitudinal direction of the magnetic tape. In this invention and this specification, the term "timing-based servo pattern" refers to a servo pattern that enables head tracking in a servo system employing the timing-based servo system. The reason why the servo pattern is formed by a pair of non-parallel magnetic stripes as described above is to inform a servo signal reading element passing over the servo pattern of its passing position. Specifically, the spacing between the pair of magnetic stripes is formed so that it continuously changes along the width direction of the magnetic tape. By reading this spacing, the servo signal reading element can determine the relative position between the servo pattern and the servo signal reading element. This relative position information enables tracking of data tracks. For this reason, a plurality of servo tracks are usually set on the servo pattern along the width direction of the magnetic tape.

[0149] A servo band is made up of a continuous servo pattern along the length of the magnetic tape. Typically, multiple servo bands are provided on a magnetic tape. For example, there are five servo bands on an LTO tape. The area between two adjacent servo bands is the data band. A data band is made up of multiple data tracks, and each data track corresponds to one of the servo tracks.

[0150] Also, in one embodiment, as disclosed in Japanese Patent Application Laid-Open No. 2004-318983, information indicating the servo band number (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 relative to 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 varies for each servo band. As a result, the recorded servo band ID is unique for each servo band, and therefore, simply by reading one servo band with a servo signal reading element, that servo band can be uniquely identified.

[0151] One method for uniquely identifying servo bands is the staggered method described in ECMA-319 (June 2001). In this staggered method, pairs of non-parallel magnetic stripes (servo stripes) are continuously arranged along the length of the magnetic tape, and are recorded so that each servo band is offset along the length of the magnetic tape. The combination of this offset between adjacent servo bands is unique across the entire magnetic tape, making it possible to uniquely identify servo bands when reading the servo pattern using two servo signal reading elements.

[0152] As specified in ECMA-319 (June 2001), each servo band also typically contains information indicating the longitudinal position of the magnetic tape (also known as "LPOS (Longitudinal Position) information"). Like UDIM information, this LPOS information is recorded by shifting the positions of a pair of servo stripes along the longitudinal direction of the magnetic tape. However, unlike UDIM information, the same signal is recorded in each servo band for this LPOS information.

[0153] It is also possible to embed information other than the UDIM information and LPOS information described above in the servo bands. In this case, the embedded information may be different for each servo band, such as UDIM information, or it may be common to all servo bands, such as LPOS information. Furthermore, 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.

[0154] The head for forming a servo pattern is called a servo write head. A servo write head typically has a pair of gaps corresponding to the pair of magnetic stripes, the number of which is equal to the number of servo bands. Typically, a core and a coil are connected to each pair of gaps. By supplying a current pulse to the coil, the magnetic field generated in the core can generate a leakage magnetic field in the pair of gaps. To form a servo pattern, a current pulse is input while running a magnetic tape over the servo write head, thereby transferring the magnetic pattern corresponding to the pair of gaps onto the magnetic tape, thereby forming the servo pattern. The width of each gap can be appropriately set depending on 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.

[0155] Before forming a servo pattern on a 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: direct current (DC) erase and alternating current (AC) erase. AC erase is performed by gradually reducing the strength of the magnetic field applied to the magnetic tape while reversing the direction of the magnetic field. DC erase, on the other hand, is performed by applying a unidirectional magnetic field to the magnetic tape. There are two other DC erase methods. The first method is horizontal DC erase, in which a unidirectional magnetic field is applied along the length of the magnetic tape. The second method is vertical DC erase, in which a unidirectional magnetic field is applied along the thickness of the magnetic tape. The erase process can be performed on the entire magnetic tape or on each servo band of the magnetic tape.

[0156] The direction of the magnetic field of the formed servo pattern is determined by the erase direction. For example, when a 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 erase direction. This increases the output of the servo signal obtained by reading the servo pattern. As shown in Japanese Patent Application Laid-Open No. 2012-53940, when a magnetic pattern is transferred to a magnetic tape that has been vertically DC erased using the gap, the servo signal obtained by reading the formed servo pattern has a unipolar pulse shape. On the other hand, when a magnetic pattern is transferred to a magnetic tape that has been horizontally DC erased using the gap, the servo signal obtained by reading the formed servo pattern has a bipolar pulse shape.

[0157] <Vertical squareness ratio> In one embodiment, the perpendicular squareness of the data tape can be, for example, 0.55 or more. From the viewpoint of improving electromagnetic conversion characteristics, it is preferably 0.60 or more, and more preferably 0.65 or more. The upper limit of the squareness is, in principle, 1.00 or less. The perpendicular squareness of the data 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. A large perpendicular squareness of the data tape is preferable from the viewpoint of improving electromagnetic conversion characteristics. The perpendicular squareness of the data tape can be controlled by known methods, such as performing a perpendicular orientation treatment.

[0158] In the present invention and this specification, the "perpendicular squareness" refers to the squareness measured in the perpendicular direction of the data tape. The "perpendicular direction" in relation to the squareness refers to the direction perpendicular to the surface of the magnetic layer, which can also be referred to as 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 suitable for insertion into a vibrating sample magnetometer is cut from the data tape to be measured. A magnetic field is applied to this sample piece perpendicular to the sample piece (perpendicular to the magnetic layer surface) using a vibrating sample magnetometer at a maximum applied magnetic field of 3979 kA / m, a measurement temperature of 296 K, and a magnetic field sweep rate of 8.3 kA / m / s. The magnetization strength of the sample piece in response to the applied magnetic field is measured. The measured magnetization strength is obtained after demagnetization field correction and after subtracting the magnetization of the sample probe of the vibrating sample magnetometer as background noise. The squareness ratio (SQ) is calculated as SQ = Mr / Ms, where Ms is the magnetization strength at the maximum applied magnetic field and Mr is the magnetization strength at zero applied magnetic field. The measurement temperature refers to the temperature of the sample piece. By setting the ambient temperature surrounding the sample piece to the measurement temperature, the temperature of the sample piece can be adjusted to the measurement temperature through thermal equilibrium.

[0159] <Reinforcing layer> In one embodiment, the magnetic tape does not have a reinforcing layer, as described below, and in another embodiment, it has a reinforcing layer, as described below. The present inventors believe that having a reinforcing layer can contribute to further suppressing the occurrence of the nonlinear component of the tape width deformation described above. Therefore, the present inventors speculate that having the reinforcing layer described below on the magnetic tape can contribute to further improving the operational stability of the drive during recording and / or playback after long-term storage.

[0160] In this invention and in this specification, the term "reinforcing layer" refers to one or more layers provided on the outermost surface of a data tape having a non-magnetic support with a magnetic layer (optionally with a non-magnetic layer as described above) on one surface and an optional backcoat layer as described above on the other surface. Such a reinforcing layer can serve to reinforce the data tape.

[0161] Fig. 2 is a cross-sectional view showing a portion of an example of a magnetic tape provided with a reinforcing layer. In the example shown in Fig. 2, the reinforcing layer is made of splice tape ST, which is typically used to join a leader tape and a data tape in a magnetic tape having a leader tape. However, as described above, the magnetic tape according to one embodiment of the present invention does not include a leader tape.

[0162] In the example shown in FIG. 2, the reinforcing layer (splice tape ST) is provided on one surface of the end of the data tape DT where the leader pin 133 is attached, and is in direct contact with the clamp 138. The reinforcing layer can be provided on either the magnetic layer side of the data tape or the opposite side, or both. For example, the side wound around the leader pin 133 can be the magnetic layer side of the data tape, and the splice tape can be attached to the backcoat layer on the other side. Known techniques for splicing tapes used to join the data tape and leader tape of magnetic tapes can be applied to the splice tape. For example, adhesive tapes having an adhesive layer on the substrate surface can be used as splice tapes. Such adhesive tapes are commercially available or can be prepared by known methods. An example of an adhesive tape is an adhesive tape having an acrylic adhesive layer on a polyester substrate. In this invention and this specification, "adhesion" also encompasses "stickiness." An "acrylic adhesive layer" refers to a layer containing a polymer and / or copolymer of a (meth)acrylic compound as an adhesive component. The term "(meth)acrylic compound" refers to a polymerizable compound having one or more polymerizable groups selected from the group consisting of acryloyl, methacryloyl, acryloyloxy, and methacryloyloxy groups per molecule. In the present invention and this specification, the term "polyester substrate" refers to a substrate containing at least one layer of polyester film. Examples of polyester substrates include a single-layer polyester film, a laminate film of two or more polyester film layers with the same constituent components, a laminate film of two or more polyester film layers with different constituent components, and a laminate film containing one or more polyester film layers and one or more non-polyester resin film layers. An adhesive layer or the like may optionally be included between two adjacent layers in the laminate film. The reinforcing layer may be provided, for example, in a region extending from the end of the end of the data tape.

[0163] The thickness of the reinforcing layer can be, for example, 5.0 μm or more, and preferably 10.0 μm or more from the viewpoint of further improving the operational stability of the drive during recording and / or playback after long-term storage. The thickness of the reinforcing layer can also be, for example, 30.0 μm or less or 25.0 μm or less. The thickness of the reinforcing layer can be determined, for example, by the methods described above for measuring various thicknesses, such as the thickness of the magnetic layer. Alternatively, for example, when splice tape is used as the reinforcing layer, the thickness can be determined using the original tape of the splice tape by the method described above for measuring the thickness of a data tape, and this thickness can be used as the thickness of the reinforcing layer (splice tape).

[0164] [Magnetic tape cartridge] One aspect of the present invention relates to a magnetic tape cartridge including the above-mentioned magnetic tape.

[0165] The magnetic tape contained in the magnetic tape cartridge is as described above in detail. The magnetic tape cartridge can be mounted in a magnetic tape device equipped with a magnetic head and used to record and / or reproduce data.

[0166] A magnetic tape cartridge generally contains a magnetic tape wound on a reel within the cartridge body. The reel is rotatably mounted within the cartridge body. Widely used magnetic tape cartridges include single-reel magnetic tape cartridges with one reel within the cartridge body and dual-reel magnetic tape cartridges with two reels within the cartridge body. When a single-reel magnetic tape cartridge is loaded into a magnetic tape device for recording and / or reproducing data on the magnetic tape, the magnetic tape is pulled out from the magnetic tape cartridge and rewound onto a reel on the magnetic tape device. A magnetic head is located in the magnetic tape transport path from the magnetic tape cartridge to the take-up reel. The magnetic tape is fed and rewound between the reel (supply reel) on the magnetic tape cartridge and the reel (take-up reel) on the magnetic tape device. For example, data is recorded and / or reproduced by contact and sliding between the magnetic head and the magnetic layer surface of the magnetic tape during this process. In contrast, a dual-reel magnetic tape cartridge is provided with both a supply reel and a take-up reel inside the magnetic tape cartridge.

[0167] In one embodiment, the magnetic tape cartridge may include a cartridge memory. The cartridge memory may be, for example, a nonvolatile memory. In one embodiment, head tilt angle adjustment information may already be recorded in the cartridge memory, or head tilt angle adjustment information may be recorded in the cartridge memory. The head tilt angle adjustment information is information for adjusting the head tilt angle while the magnetic tape is running in the magnetic tape device. For example, the head tilt angle adjustment information may record the value of the servo band spacing at each position in the longitudinal direction of the magnetic tape when data is recorded. For example, when reproducing data recorded on the magnetic tape, the value of the servo band spacing may be measured during reproduction, and the head tilt angle may be changed by a control device of the magnetic tape device so that the absolute value of the difference between the servo band spacing measured during reproduction and the servo band spacing recorded in the cartridge memory at the same longitudinal position during recording approaches zero. The head tilt angle may be, for example, the angle θ described above.

[0168] The magnetic tape and magnetic tape cartridge described above can be suitably used in a magnetic tape device (in other words, a magnetic recording and / or playback system) that records and / or plays back data at different head tilt angles. In one embodiment of such a magnetic tape device, data can be recorded and / or played back by changing the head tilt angle while the magnetic tape is running. For example, the head tilt angle can be changed according to dimensional information in the width direction of the magnetic tape obtained while the magnetic tape is running. Also, for example, there can be a use mode in which the head tilt angle during one recording and / or playback is different from the head tilt angle during subsequent recording and / or playback, and the head tilt angle is fixed and not changed during each recording and / or playback magnetic tape run.

[0169] [Magnetic tape device] One aspect of the present invention relates to a magnetic tape device including the above-mentioned magnetic tape, in which data can be recorded on the magnetic tape and / or data recorded on the magnetic tape can be reproduced, for example, by bringing a magnetic head into contact with the surface of the magnetic layer of the magnetic tape and sliding it over it.

[0170] For example, magnetic tape is treated as a removable medium (so-called exchangeable medium), and a magnetic tape cartridge containing the magnetic tape is inserted into and removed from a magnetic tape device.

[0171] In this invention and this specification, the term "magnetic tape device" refers to a device that can record data on a magnetic tape and / or reproduce data recorded on a magnetic tape. Such a device is generally called a drive.

[0172] <Magnetic head> The magnetic tape device can include a magnetic head. The configuration of the magnetic head and the angle θ, which is the head tilt angle, are as described above with reference to FIGS. 7 to 9. When the magnetic head includes a reproducing element, the reproducing element is preferably a magnetoresistive (MR) element that can read information recorded on a magnetic tape (specifically, a data tape) with high sensitivity. As the MR element, various known MR elements (e.g., a GMR (Giant Magnetoresistive) element, a TMR (Tunnel Magnetoresistive) element, etc.) can be used. Hereinafter, a magnetic head that records data and / or reproduces recorded data is also referred to as a "recording / reproducing head." An element for recording data (a recording element) and an element for reproducing data (a reproducing element) are collectively referred to as a "magnetic head element."

[0173] When recording and / or reproducing data, tracking can be performed using servo signals. That is, by making the servo signal reading element follow a predetermined servo track, the magnetic head 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 read / write head can also record and / or read data from other data bands by using the UDIM information described above to move the servo signal read element to a specific servo band and start tracking that servo band.

[0174] FIG. 11 shows an example of the arrangement of data bands and servo bands. In FIG. 11, multiple servo bands 1 are sandwiched between guide bands 3 on the magnetic layer of the data tape of the magnetic tape MT. Multiple regions 2 sandwiched between two servo bands form a data band. Servo patterns are magnetized regions formed by magnetizing specific regions of the magnetic layer with a servo write head. The regions magnetized by the servo write head (the positions where servo patterns are formed) are determined by standards. For example, in the industry-standard LTO Ultrium format tape, multiple servo patterns inclined with respect to the tape width direction are formed on the servo bands during magnetic tape manufacturing, as shown in FIG. 12. Specifically, in FIG. 12, a servo frame SF on servo band 1 is composed of a servo subframe 1 (SSF1) and a servo subframe 2 (SSF2). Servo subframe 1 is composed of an A burst (labeled A in FIG. 12) and a B burst (labeled B in FIG. 12). 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, servo subframe 2 is composed of a C burst (C in FIG. 12) and a D burst (D in FIG. 12). The C burst is composed of servo patterns C1 through C4, and the D burst is composed of servo patterns D1 through D4. These 18 servo patterns are arranged in subframes, arranged in groups of 5 and 4, in a 5, 5, 4, 4 arrangement, and are used to identify servo frames. For illustrative purposes, FIG. 12 shows one servo frame. However, in reality, multiple servo frames are arranged in each servo band in the running direction on the magnetic layer of a magnetic tape that uses timing-based servo head tracking. In FIG. 12, the arrow indicates the running direction of the magnetic tape. For example, an LTO Ultrium format tape typically has more than 5,000 servo frames per meter of tape length on each servo band on the magnetic layer.

[0175] In one embodiment, in the magnetic tape device, the head tilt angle can be changed while the magnetic tape is running within the magnetic tape device. The head tilt angle is, for example, the angle θ formed by the axis of the element array with respect to the width direction of the magnetic tape. The angle θ is as described above. For example, by providing an angle adjustment unit that adjusts the angle of the magnetic head module in the recording / reproducing head unit of the magnetic head, the angle θ can be variably adjusted while the magnetic tape is running. Such an angle adjustment unit can include, for example, a rotation mechanism that rotates the module. Publicly known technology can be applied to the angle adjustment unit.

[0176] Regarding the head tilt angle during magnetic tape running, if the magnetic head includes multiple modules, the angle θ described with reference to Figures 7 to 9 can be defined for randomly selected modules. initial can be set to be greater than or equal to 0°. initial The larger the angle θ, the larger the change in the effective distance between the servo signal read elements relative to the change in angle θ, which is preferable in terms of the ability to adjust the effective distance between the servo signal read elements in response to changes in the width direction of the magnetic tape. initial is preferably 1° or more, more preferably 5° or more, and even more preferably 10° or more. On the other hand, with regard to the angle formed by the magnetic layer surface and the contact surface of the magnetic head when the magnetic tape runs and comes into contact with the magnetic head (generally called the "wrap angle"), keeping the deviation in the tape width direction small is effective in increasing the uniformity in the tape width direction of the friction generated by contact between the magnetic head and the magnetic tape while the magnetic tape is running. Furthermore, increasing the uniformity of the friction in the tape width direction is desirable from the viewpoint of the position tracking ability and running stability of the magnetic head. From the viewpoint of reducing the deviation in the tape width direction of the wrap angle, θ initial is preferably 45° or less, more preferably 40° or less, and even more preferably 35° or less.

[0177] Regarding the change in angle θ during magnetic tape running, while the magnetic tape is running in the magnetic tape device for recording data on the magnetic tape and / or for reproducing data recorded on the magnetic tape, the angle θ of the magnetic head is changed from θ at the start of running. initial When the angle θ changes from max and Δθ min The maximum value of the angle θ during magnetic tape running is θ max and the minimum value is θ min Note that "max" is an abbreviation for maximum, and "min" is an abbreviation for minimum. Δθ max =θ max -θ initial Δθ min =θ initial -θ min

[0178] In one embodiment, Δθ can be greater than 0.000°, and is preferably 0.001° or greater, more preferably 0.010° ​​or greater, from the viewpoint of the ability to adjust the effective distance between servo signal read elements in response to dimensional changes in the magnetic tape width direction. Furthermore, from the viewpoint of ease of ensuring synchronization of recorded data and / or reproduced data between multiple magnetic head elements during data recording and / or reproduction, Δθ is preferably 1.000° or less, more preferably 0.900° or less, even more preferably 0.800° or less, even more preferably 0.700° or less, and even more preferably 0.600° or less.

[0179] 8 and 9, the axis of the element array is inclined toward the magnetic tape running direction. However, the present invention is not limited to such an example. The present invention also includes an embodiment in which the axis of the element array in the above-mentioned magnetic tape device is inclined toward the direction opposite to the magnetic tape running direction.

[0180] θ is the head tilt angle when the magnetic tape starts running initialcan be set by the control device of the magnetic tape device, etc. Regarding the head tilt angle during magnetic tape running, FIG. 13 is an explanatory diagram of a method for measuring the angle θ during magnetic tape running. The angle θ during magnetic tape running can be determined, for example, by the following method. When determining the angle θ during magnetic tape running by the following method, the angle θ is changed within a range of 0 to 90° during magnetic tape running. In other words, if the axis of the element array is tilted toward the magnetic tape running direction at the start of magnetic tape running, the element array is not tilted during magnetic tape running so that the axis of the element array is tilted toward the opposite direction from the magnetic tape running direction at the start of magnetic tape running. Conversely, if the axis of the element array is tilted toward the opposite direction from the magnetic tape running direction at the start of magnetic tape running, the element array is not tilted during magnetic tape running so that the axis of the element array is tilted toward the magnetic tape running direction at the start of magnetic tape running. The phase difference (i.e., time difference) ΔT between the playback signals of a pair of servo signal read elements 1 and 2 is measured. ΔT can be measured using a measurement unit included in the magnetic tape drive. The configuration of such a measurement unit is well known. The distance L between the center of servo signal read element 1 and the center of servo signal read element 2 can be measured using an optical microscope or the like. When the magnetic tape running speed is v, the distance between the centers of the two servo signal read elements in the magnetic tape running direction is L sin θ, and the relationship L sin θ = v × ΔT holds. Therefore, the angle θ during magnetic tape running can be calculated using the formula "θ = arcsin(vΔT / L)." Note that the right diagram in Figure 13 shows an example in which the axis of the element array is tilted toward the magnetic tape running direction. In this example, the phase difference (i.e., time difference) ΔT between the phase of the playback signal of servo signal read element 1 and the phase of the playback signal of servo signal read element 2 is measured. When the axis of the element array is tilted in the opposite direction to the running direction of the magnetic tape, θ can be found by the above method, except that ΔT is measured as the phase difference (i.e., time difference) between the phase of the playback signal of servo signal read element 2 and the phase of the playback signal of servo signal read element 1. The measurement pitch of the angle θ, i.e., the measurement interval of the angle θ relative to the tape longitudinal direction, can be selected to be appropriate depending on the frequency of the tape width deformation relative to the tape longitudinal direction. As an example, the measurement pitch can be set to 250 μm.

[0181] <Configuration of magnetic tape device> A magnetic tape device 10 shown in FIG. 14 controls a recording / 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 tape device 10 has a configuration that can detect and adjust tension applied to the magnetic tape in the longitudinal direction from spindle motors 17A, 17B that control the rotation of the magnetic tape cartridge reel and take-up reel and their drive devices 18A, 18B. The magnetic tape device 10 has a configuration in which a magnetic tape cartridge 13 can be loaded. The magnetic tape device 10 has a cartridge memory read / write device 14 that can read and write data from and to a cartridge memory 131 in the magnetic tape cartridge 13 . A leader pin attached to the magnetic tape MT is pulled out from the magnetic tape cartridge 13 loaded into the magnetic tape device 10 by an automatic loading mechanism or manually, and the magnetic tape MT passes over the recording / playback head via guide rollers 15A and 15B with the magnetic layer surface in contact with the recording / playback head surface of the recording / 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, allowing magnetic tape MT to run at a desired speed and tension. Servo patterns pre-formed on the magnetic tape can be used to control the tape speed and head tilt angle. A tension detection mechanism may be provided between magnetic tape cartridge 13 and take-up reel 16 to detect tension. In addition to control by spindle motors 17A and 17B, tension control may also be performed using guide rollers 15A and 15B. 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.

[0182] The control device 11 includes, for example, a control unit, a storage unit, a communication unit, and the like.

[0183] The recording / playback head unit 12 is composed of, for example, a recording / playback head, a servo tracking actuator that adjusts the position of the recording / playback head in the track width direction, a recording / playback amplifier 19, a connector cable for connecting to the control device 11, etc. The recording / playback head is composed of, for example, a recording element that records data on the magnetic tape, a reproducing element that reproduces the data from the magnetic tape, and a servo signal reading element that reads the servo signals recorded on the magnetic tape. One magnetic head may have, for example, one or more recording elements, one or more reproducing elements, and one or more servo signal reading elements. Alternatively, each element may be provided separately in multiple magnetic heads corresponding to the running direction of the magnetic tape.

[0184] The recording / playback head unit 12 is configured to be able to record data onto the magnetic tape MT in response to a command from the control device 11. It is also configured to be able to play back the data recorded on the magnetic tape MT in response to a command from the control device 11.

[0185] The control device 11 has a mechanism for determining the running position of the magnetic tape MT from servo signals read from the servo bands and controlling the servo tracking actuator so that the recording element and / or reproducing element is positioned at the target running position (track position). This track position control is performed, for example, by feedback control. The control device 11 also has a mechanism for determining the servo band spacing from servo signals read from two adjacent servo bands while the magnetic tape MT is running. The control device 11 can store information about the determined servo band spacing in its internal storage unit, cartridge memory 131, an external connected device, or the like. The control device 11 can also change the head tilt angle according to dimensional information about the width of the running magnetic tape. This allows the effective distance between the servo signal reading elements to approach or match the spacing between the servo bands. The dimensional information can be obtained using servo patterns pre-formed on the magnetic tape. For example, while the magnetic tape is running in the magnetic tape device, the angle θ formed by the axis of the element array with respect to the width direction of the magnetic tape can be changed in accordance with the dimensional information of the magnetic tape in the width direction acquired during the running. The head tilt angle can be adjusted, for example, by feedback control. Furthermore, the head tilt angle can also be adjusted, for example, by the method described in JP-A-2016-524774 (Patent Document 1) or US 2019 / 0164573 A1 (Patent Document 2). [Example]

[0186] The present invention will be described below based on examples. However, the present invention is not limited to the embodiments shown in the examples. "Parts" and "%" described below represent "parts by mass" and "% by mass", respectively. Furthermore, the steps and evaluations described below were carried out in an environment with a temperature of 23°C ± 1°C unless otherwise specified. "eq" described below is equivalent, a unit that cannot be converted to SI units.

[0187] [Abrasive liquid] 100.0 parts of the abrasive (alumina powder) shown in Table 1 was mixed with the amount of 2,3-dihydroxynaphthalene (manufactured by Tokyo Chemical Industry Co., Ltd.) shown in Table 1, 31.3 parts of a 32% solution (solvent: a mixed solvent of methyl ethyl ketone and toluene) of a polyester polyurethane resin having SO3Na groups as polar groups (UR-4800 (polar group amount: 80 meq / kg) manufactured by Toyobo Co., Ltd.), and 570.0 parts of a 1:1 (mass ratio) mixed solution of methyl ethyl ketone and cyclohexanone as the solvent, and dispersed in the presence of zirconia beads (bead diameter: 0.1 mm) using a paint shaker for the time (bead dispersion time) shown in Table 1. After dispersion, the dispersion was separated from the beads using a mesh, and the resulting dispersion was centrifuged. The centrifugation was carried out using a Hitachi Koki CS150GXL centrifuge (using a Hitachi Koki S100AT6 rotor) at the rotation speed (rpm: rotations per minute) shown in Table 1 for the time (centrifugation time) shown in Table 1. This centrifugation causes particles with relatively large particle sizes to settle, and particles with relatively small particle sizes to disperse in the supernatant. The supernatant was then recovered by decantation. In the Examples, Comparative Examples, and Reference Examples described below, this recovered liquid was used as the abrasive liquid. Before being used to prepare a magnetic layer-forming composition, the abrasive liquid was subjected to ultrasonic dispersion treatment for 0.5 minutes using a batch-type ultrasonic device (20 kHz, 300 W).

[0188] [Table 1]

[0189] [Ferromagnetic powder] In Table 2, "BaFe" is hexagonal barium ferrite powder (coercive force Hc: 196 kA / m, average particle size (average plate diameter): 24 nm).

[0190] In Table 2, "SrFe1" is a hexagonal strontium ferrite powder produced by the following method. 1707 g of SrCO3, 687 g of H3BO3, 1120 g of Fe2O3, 45 g of Al(OH)3, 24 g of BaCO3, 13 g of CaCO3, and 235 g of Nd2O3 were weighed and mixed in a mixer to obtain a raw material mixture. The resulting raw material mixture was melted in a platinum crucible at a melting temperature of 1390°C, and the melt was stirred while heating the tapping hole at the bottom of the platinum crucible, causing the melt to be poured into a rod shape at a rate of approximately 6 g / sec. The tapped liquid was rolled and quenched using 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 rate of 3.5°C / min, and held at that temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles. The crystallized material obtained above, containing hexagonal strontium ferrite particles, was then coarsely crushed in a mortar. 1,000 g of 1 mm zirconia beads and 800 ml of a 1% aqueous acetic acid solution were then added to the glass bottle containing the crystalline material, followed by dispersion 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 allowed to stand at 100°C for 3 hours to dissolve the glass components, after which it was precipitated in a centrifuge, washed by repeated decantation, and dried for 6 hours in a heating furnace at 110°C to obtain hexagonal strontium ferrite powder. The average particle size of the hexagonal strontium ferrite powder obtained above was 18 nm, and the activation volume was 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 filtrate was subjected to elemental analysis using an ICP analyzer to determine the neodymium atom content in the surface layer. Separately, 12 mg of sample powder was collected from the hexagonal strontium ferrite powder obtained above, and this sample powder was completely dissolved under the dissolution conditions exemplified above. The filtrate thus obtained was subjected to elemental analysis using an ICP analyzer to determine the bulk content of neodymium atoms. The neodymium atom content (bulk content) of the hexagonal strontium ferrite powder obtained above relative to 100 atomic percent of iron atoms was 2.9 atomic percent. The neodymium atom content in the surface layer was 8.0 atomic percent. 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. The powder obtained above was confirmed to have 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 (M-type) hexagonal ferrite crystal structure. Furthermore, the crystalline phase detected by X-ray diffraction analysis was a single magnetoplumbite phase. 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

[0191] In Table 2, "SrFe2" is a hexagonal strontium ferrite powder produced by the following method. 1725 g of SrCO3, 666 g of H3BO3, 1332 g of Fe2O3, 52 g of Al(OH)3, 34 g of CaCO3, and 141 g of BaCO3 were weighed and mixed in a mixer to obtain a raw material mixture. The resulting raw material mixture was melted in a platinum crucible at a melting temperature of 1380°C, and the melt was stirred while heating the tapping hole at the bottom of the platinum crucible, causing the melt to be poured into a rod shape at a rate of approximately 6 g / sec. The tapped liquid was rolled and quenched using a water-cooled twin roller 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 this temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles. The crystallized material obtained above, containing hexagonal strontium ferrite particles, was then coarsely crushed in a mortar. 1,000 g of 1 mm zirconia beads and 800 ml of a 1% aqueous acetic acid solution were then added to the glass bottle containing the crystalline material, followed by dispersion 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 allowed to stand at 100°C for 3 hours to dissolve the glass components, after which it was precipitated in a centrifuge, washed by repeated decantation, and dried for 6 hours in a heating furnace at 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.

[0192] In Table 2, "ε-iron oxide" is ε-iron oxide powder prepared by the following method. 8.3 g of iron(III) nitrate nonahydrate, 1.3 g of gallium(III) nitrate octahydrate, 190 mg of cobalt(II) nitrate hexahydrate, 150 mg of titanium(IV) sulfate, and 1.5 g of polyvinylpyrrolidone (PVP) were dissolved in 90 g of pure water. While stirring using a magnetic stirrer, 4.0 g of 25% aqueous ammonia was added in air at an ambient temperature of 25°C. The mixture was stirred for 2 hours at 25°C. A citric acid solution prepared by dissolving 1 g of citric acid in 9 g of pure water was added to the resulting solution and stirred for 1 hour. The precipitated powder was collected by centrifugation, washed with pure water, and dried in a heating oven at 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 resulting dispersion was heated to 50°C, and 40g of a 25% aqueous ammonia 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 resulting reaction solution, and the precipitated powder was collected by centrifugation, washed with pure water, and dried for 24 hours in a heating furnace at 80°C to obtain a precursor of the 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 the impurity silicate compound from the heat-treated ferromagnetic powder precursor. Thereafter, the silicate 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). It was found that the powder consisted 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 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) without containing α-phase 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.

[0193] 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 using a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd.) by the method described above. The mass magnetization σs is a value measured at a magnetic field strength of 15 kOe using a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd.).

[0194] [Non-magnetic powder for magnetic layer] In Table 2, in the Examples, Comparative Examples, and Reference Examples where the "Average Plate Diameter of Non-Magnetic Powder" and "Average Plate Thickness of Non-Magnetic Powder" are listed in the "Magnetic Layer" column, the magnetic layer was formed using a non-magnetic powder composed of plate-like particles with an average plate diameter and average plate thickness listed in Table 2. These non-magnetic powders were prepared by the methods described below. The metal hydroxide and water were mixed in a sealed container (mixing time and molar concentration of the metal hydroxide aqueous solution: see Table 2). In Table 2, "h" is an abbreviation for "hour (s)." The mixed aqueous solution was heated for 10 days in an autoclave with the internal temperature set at 270° C. After heating, the produced particles were collected by centrifugation. Non-magnetic powders were prepared in this manner: alumina powder was prepared by using aluminum hydroxide as the metal hydroxide, zirconia powder was prepared by using zirconium hydroxide, and ceria powder was prepared by using cerium hydroxide.

[0195] In Table 2, "CS" listed under "Type of non-magnetic powder" in the "Magnetic layer" column is an abbreviation for colloidal silica. The colloidal silica particle shape was spherical or elliptical.

[0196] In Table 2, the "average plate diameter of non-magnetic powder," "average plate thickness of non-magnetic powder," and "average particle size of non-magnetic powder" listed in the "Magnetic layer" column were measured using a Hitachi H-9000 transmission electron microscope and Carl Zeiss KS-400 image analysis software, and were determined as described above.

[0197] [Example 1] (1) Formulation of the composition for forming the magnetic layer (Magnetic liquid) Ferromagnetic powder (see Table 2): 100.0 parts SO3Na group-containing polyurethane resin: 14.0 parts Weight average molecular weight: 70,000, SO3Na group: 0.4meq / g Cyclohexanone: 150 parts Methyl ethyl ketone: 150 parts (abrasive liquid) The abrasive liquid prepared by the method described above was used in an amount such that the content of the abrasive in the abrasive liquid was 0.8 parts per 100.0 parts of the ferromagnetic powder. (Non-magnetic powder) Non-magnetic powder listed in Table 2: 0.2 parts (Other ingredients) Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., number average molecular weight 300): See Table 2 Stearic acid: see Table 2 Butyl stearate: 10.0 parts Polyisocyanate (Coronate manufactured by Nippon Polyurethane Co., Ltd.): 2.5 parts Cyclohexanone: 200.0 parts Methyl ethyl ketone: 200.0 parts

[0198] (2) Formulation of the composition for forming the nonmagnetic layer α-iron oxide powder (average particle volume: see Table 2): 100.0 parts Carbon black (average particle size: 20 nm, pH: see Table 2): 25.0 parts SO3Na group-containing polyurethane resin: 18 parts Weight average molecular weight: 70,000, SO3Na group: 0.2meq / g Stearic acid: 1.0 parts Cyclohexanone: 300.0 parts Methyl ethyl ketone: 300.0 parts

[0199] (3) Formulation of the composition for forming the backcoat layer Carbon black: 100.0 parts Cabot BP-800, average particle size: 17 nm SO3Na group-containing polyurethane resin (SO3Na group: 70 eq / ton): 20.0 parts Vinyl chloride resin containing OSO3K group (OSO3K group: 70 eq / ton): 30.0 parts Cyclohexanone: 140.0 parts Methyl ethyl ketone: 170.0 parts Butyl stearate: 2.0 parts Stearic acid amide: 0.1 parts

[0200] (4) Preparation of compositions for forming each layer The magnetic liquid was prepared by dispersing the above components for 24 hours using a batch-type vertical sand mill. Zirconia beads with a diameter of 0.5 mm were used as dispersion beads. The magnetic liquid and abrasive liquid were mixed with the non-magnetic powder and other ingredients, and then dispersed using a batch-type ultrasonic device (20 kHz, 300 W) (dispersion time: see Table 2).The mixture was then filtered using a filter with a pore size of 0.5 μm to prepare a magnetic layer-forming composition. The non-magnetic layer-forming composition was prepared by dispersing the above components for 24 hours using a batch-type vertical sand mill. Zirconia beads with a diameter of 0.1 mm were used as dispersion beads. The resulting dispersion was filtered using a filter with a pore size of 0.5 μm to prepare the non-magnetic layer-forming composition. The backcoat layer-forming composition was prepared by kneading the above components in a continuous kneader and then dispersing them in a sand mill. 40.0 parts of polyisocyanate (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 1000.0 parts of methyl ethyl ketone were added to the resulting dispersion, and the mixture was filtered through a filter with a pore size of 1 μm to prepare a backcoat layer-forming composition.

[0201] (5) Production of magnetic tapes (data tapes) The magnetic tape was produced according to the manufacturing process shown in Figure 10. The details are as follows. A 3.7 μm thick polyethylene naphthalate support was delivered from a delivery section, and a nonmagnetic layer-forming composition was applied to one surface in a first coating section so that the thickness after drying would be 0.7 μm to form a coating layer. While the formed coating layer was still wet, it was passed through a cooling zone adjusted to an atmospheric temperature of 0°C to perform a cooling process (cooling zone residence time: 1 second), and then passed through a first heat treatment zone at a drying temperature (atmospheric temperature, the same applies below) of 105°C to perform a heat drying process, thereby forming a nonmagnetic layer. The magnetic layer-forming composition prepared above was then applied to the non-magnetic layer in a second coating section so that the thickness after drying would be 0.1 μm, forming a coating layer. While this coating layer was still wet, a magnetic field with a strength of 0.5 T was applied perpendicularly to the surface of the magnetic layer-forming composition coating layer in an orientation zone to perform a vertical orientation treatment, and the coating layer was then dried in a second heat treatment zone at a drying temperature of 105° C. Then, in a third coating section, the backcoat layer forming composition prepared above was applied to the surface of the polyethylene naphthalate support opposite to the surface on which the non-magnetic layer and magnetic layer were formed, to form a coating layer with a dry thickness of 0.3 μm, and the formed coating layer was dried in a third heat treatment zone at a drying temperature of 105°C. Thereafter, calendering (surface smoothing) was carried out under the calendering conditions shown in Table 2 using calender rolls consisting of only metal rolls. Thereafter, the film was subjected to a heat treatment for 36 hours in an atmosphere at 70° C. After the heat treatment, the film was slit into a width of 1 / 2 inch to prepare a magnetic tape. The magnetic layer of the prepared magnetic tape was demagnetized and then a servo signal was recorded on the magnetic layer using a commercially available servo writer. This resulted in a magnetic tape with data bands, servo bands, and guide bands arranged in accordance with the LTO (Linear Tape-Open) Ultrium format, and with a servo pattern (timing-based servo pattern) on the servo band arranged and shaped in accordance with the LTO Ultrium format. The servo pattern thus formed conforms to the specifications of JIS (Japanese Industrial Standards) X6175:2006 and Standard ECMA-319 (June 2001). The total number of servo bands was five, and the total number of data bands was four. In this way, a magnetic tape (960 m long) on ​​which servo signals were recorded was produced as a data tape.

[0202] (6) Preparation of magnetic tape with leader pin The magnetic layer side of the data tape prepared above was wound around a leader pin, and the backcoat layer side was held down with a C-shaped clamp, thereby attaching a leader pin directly to one end of the data tape.

[0203] The presence of a compound containing an ammonium salt structure of an alkyl ester anion represented by formula 1, formed from polyethyleneimine and stearic acid, in the magnetic layer of a magnetic tape can be confirmed by the following method. A sample is cut from the magnetic tape, and the magnetic layer surface (measurement area: 300 μm × 700 μm) is subjected to X-ray photoelectron spectroscopy using an ESCA instrument. Specifically, wide scan measurements are performed using the ESCA instrument under the following measurement conditions. The measurement results show peaks at the position of the binding energy of the ester anion and the position of the binding energy of the ammonium cation. Equipment: Shimadzu AXIS-ULTRA Excitation X-ray source: Monochromated Al-Kα radiation Scan range: 0 to 1200 eV Pass energy: 160 eV Energy resolution: 1 eV / step Capture time: 100ms / step Accumulation count: 5 In addition, a sample piece 3 cm long was cut out from the magnetic tape, and the magnetic layer surface was measured by ATR-FT-IR (Attenuated Total Reflection-Fourier Transform-Infrared Spectrometer) (reflection method). - The wavenumber corresponding to the absorption of -1 or 1430cm -1 ), and the wavenumber corresponding to the absorption of ammonium cation (2400 cm -1 ) absorption is confirmed.

[0204] [Examples 2 to 16, Comparative Examples 1 to 5, Reference Examples 1 and 2] A magnetic tape with a leader pin was obtained by the method described for Example 1, except that the items shown in Table 2 were changed as shown in Table 2. In producing the magnetic tapes of Reference Examples 1 and 2, one end of the data tape was joined to the end of the leader tape (width: 1 / 2 inch) using a splice tape (width: 1 / 2 inch) as shown in FIG. 16. The leader tape used was a magnetic tape having a non-magnetic support and a magnetic layer containing ferromagnetic powder, a non-magnetic layer containing non-magnetic powder between the non-magnetic support and the magnetic layer, and a backcoat layer containing non-magnetic powder on the surface of the non-magnetic support opposite the surface with the magnetic layer. The splice tape used was a commercially available adhesive tape having an adhesive layer on the surface of the substrate. The splice tape was attached to the backcoat layer side of the data tape and leader tape. A leader pin was attached to the end of the leader tape. In the preparation of the magnetic tapes of Examples 10 to 13, for which "Yes" is written in the "Reinforcement with splice tape" column in Table 2, splice tape (width: 1 / 2 inch) was applied to the backcoat layer side of the data tape before attaching the leader pin, as shown in Figure 2. The splice tape used was a commercially available adhesive tape with an acrylic adhesive layer on the surface of a polyester substrate. In Table 2, the thickness of the splice tape used for reinforcement is shown in parentheses in the "Reinforcement with splice tape" column.

[0205] For each Example, Comparative Example, and Reference Example, six magnetic tapes were produced by the above method, and each was used for the following evaluations (1) to (6).

[0206] [Evaluation method] (1)F 10° (Leader pin attachment end area) The leader pin was removed from each of the magnetic tapes of the Examples and Comparative Examples, and the F was measured by the method described above in an environment of a temperature of 23°C and a relative humidity of 50%. 10° The area (edge ​​region on the side where the leader pin is attached) was measured. A commercially available LTO9 head (manufactured by IBM) was used as the LTO9 head. For the magnetic tape of Reference Example 1 and the magnetic tape of Reference Example 2, which have a leader tape, the end of the data tape on the joining side with the leader tape was set as the starting point (0 cm) of the longitudinal position, and the region within the range from the 5 cm position to the 20 cm position was set as the end region on the leader pin attachment side, and the friction force F obtained by the above method was set as F 10° (Leader pin attachment end region).

[0207] (2) Spc and Spc width direction σ on the magnetic layer surface of the data tape The AFM measurement conditions were as follows: Spc and the width direction σ of Spc on the magnetic layer surface of the data tape were determined by the method described above. The AFM data analysis software (Nanoscope Analysis) provided by BRUKER was used. An AFM (Bruker Nanoscope 5) was used in peak force tapping mode to measure an area of ​​40 μm × 40 μm on the surface of the magnetic layer of the data tape. A Bruker SCANASYST-AIR probe was used, with a resolution of 512 pixels × 512 pixels and a scan speed of 512 seconds per screen (512 pixels × 512 pixels).

[0208] (3) Nonlinear component of tape width deformation For each of the magnetic tapes of the Examples, Comparative Examples, and Reference Examples, the nonlinear component of the tape width deformation caused by storage for 20 days in an environment of a temperature of 60°C and a relative humidity of 20% was measured using the method described above.

[0209] (4) Data tape thickness Ten tape samples (5 cm long) were cut from any portion of the data tape of each magnetic tape in the Examples, Comparative Examples, and Reference Examples, and the thickness was measured by stacking these tape samples. The thickness was measured using a digital thickness meter equipped 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) as the tape thickness. The data tape thickness for all magnetic tapes was 4.8 μm. The thickness of the splice tape used as the reinforcing layer shown in Table 2 was determined by the above method using the original splice tape. The thicknesses of the magnetic layer, non-magnetic layer, and backcoat layer of each magnetic tape in the Examples, Comparative Examples, and Reference Examples were confirmed by cross-sectional observation as described above to be the thicknesses described above.

[0210] (5) Driving stability In an environment of a temperature of 23°C and a relative humidity of 50%, running stability was evaluated by the following method. Using magnetic tape cartridges containing the magnetic tapes of the example, comparative example, and reference example, data was recorded and reproduced using a magnetic tape device configured as shown in Figure 14. The arrangement of modules included in the recording and reproduction head mounted in the recording and reproduction head unit is "recording module-playback module-recording module" (total number of modules: 3). Each module has 32 magnetic head elements (Ch0 to Ch31), and these magnetic head elements are sandwiched between a pair of servo signal reading elements to form an element array. The reproducing element width of the reproducing element included in the reproducing module is 0.8 μm. Data was recorded and reproduced using the following method to evaluate the running stability during reproduction, with the head tilt angle set to 10°. This head tilt angle is the angle θ formed by the axis of the element array in the reproduction module with respect to the width direction of the magnetic tape at the start of the run. The angle θ was set by the control device of the magnetic tape device when the magnetic tape started to run, and the head tilt angle was fixed while the magnetic tape was running. A magnetic tape cartridge is inserted into a magnetic tape device and the magnetic tape is loaded. Next, while performing servo tracking, the recording / playback head unit records pseudo-random data with a specific data pattern onto the magnetic tape. A constant tension is applied along the length of the tape during this process. Simultaneously with the data recording, the servo band spacing along the entire length of the tape is measured every 1 meter 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, with a constant tension applied to the tape in the longitudinal direction. The standard deviation (σPES) of the widthwise read position PES (Position Error Signal) based on the servo signal obtained by the servo signal reader during playback was used as an index to evaluate running stability. The PES can be calculated using the following method. The servo pattern dimensions are required to calculate the PES. The servo pattern dimension standards vary depending on the LTO generation. First, we measured the average distance AC between the four corresponding stripes of the A and C bursts and the azimuth angle α of the servo pattern using a magnetic force microscope or similar. The average time between the five stripes corresponding to the A and B bursts over the length of one LPOS word is defined as a. The average time between the four corresponding stripes of the A and C bursts over the length of one LPOS word is defined as b. The value defined as AC × (1 / 2 - a / b) / (2 × tan(α)) is the widthwise read position PES (Position Error Signal) based on the servo signal obtained by the servo signal reader over the length of one LPOS word. With regard to the magnetic tape, the end of the tape wound onto the reel of the magnetic tape cartridge is called the cartridge reel winding end, and a leader pin is attached to the end opposite the cartridge winding end. For magnetic tapes (Examples and Comparative Examples) in which a leader pin is attached to the end of the data tape, the end of the end where the leader pin is attached was set to 0 m, and the standard deviation of PES (σPES) determined by the above method was calculated for a region in the tape longitudinal direction over a length of 30 m to 200 m. For magnetic tapes (Reference Examples) having a leader tape, the end of the data tape end on the joint side with the leader tape was set to 0 m, and the standard deviation of PES (σPES) determined by the above method was calculated for a region in the tape longitudinal direction over a length of 30 m to 200 m.

[0211] (6) Recording and playback performance The recording and reproducing performance of each of the magnetic tapes of the Examples, Comparative Examples and Reference Examples was evaluated by the following method. The magnetic head used was equipped with a reproducing module including an element array with 10 or more channels of reproducing elements with a reproducing element width of 0.2 μm or less between a pair of servo signal reading elements, and a recording module including an element array with 10 or more channels of recording elements with a recording element width of 1.5 times or more between a pair of servo signal reading elements. In the element array, the spacing between two adjacent elements (i.e., two adjacent reproducing elements and two adjacent recording elements) in the head width direction was 40 μm or more. The environment for recording and reproducing data was a temperature of 20 to 25°C and a relative humidity of 40 to 60%. A magnetic tape device with a magnetic tape and magnetic head attached to a tape transport system (reel tester) was placed in this environment for at least 24 hours, after which data was recorded and reproduced. The recording and reproducing amplifier attached to the tape transport system of the magnetic tape device was the same as the recording and reproducing amplifier described above for measuring the nonlinear component of tape width deformation. During data recording and reproduction, the servo following and dynamic track position control (change in head tilt angle) described above were performed. Data recording and reproduction were carried out in detail as follows. Signals were recorded using the recording element while the magnetic tape was running at a constant speed of 5 m / s. The bit sequence used for recording was a 255-bit pseudo random bit sequence (PRBS) generated according to the generating polynomial x^8+x^6+x^5+x^4+1. The symbol "^" indicates exponentiation. The linear recording density was 600 kbpi. The unit "kbpi" is the unit of linear recording density (cannot be converted to SI units). Shingled recording was performed on three or more tracks so that the difference (PES1+PES2) / 2 between adjacent tracks was 1.5 times the playback track width. The magnetic pattern recorded on the magnetic tape is reproduced by the next reproducing element (i.e., the reproducing element with the same channel number) and the signal is amplified by the reproducing amplifier. The reproduced signal is processed by a PLL (Phase Lock Loop) and AGC (Auto Gain Control), and then decoded into a bit sequence based on DD-NPML (Data Dependent Noise Predictive Maximum Likelihood) signal processing. The recorded bit sequence and the reproduced and decoded bit sequence are compared bit by bit, and if the two bits differ, a single bit error is counted. Data is compared over 10 Mbits, and the cumulative error bit count divided by 10 Mbits is defined as the bit error rate. It was confirmed that the bit error rate for the reproduced signal immediately after recording was 1 / 1000 or less in all channels. Next, the magnetic tape was stored for 20 days in an environment of a temperature of 60° C. and a relative humidity of 20% while wound on the reel of the reel tester. After the storage described above, the magnetic tape was removed from the storage environment and placed in the same magnetic tape device as before storage, in an environment with a temperature of 20-25°C and a relative humidity of 40-60% for at least 24 hours. Then, under the same environment, the data tracks recorded before storage were played back (no recording was performed). Only data tracks with data tracks recorded on both sides were played back. The bit error rate was calculated for all channels, and channels with a bit error rate of 1 / 100 or higher were considered defective. The recording and playback performance was evaluated according to the following criteria. (Evaluation criteria) A: The ratio of defective channels to the total number of channels is less than 5% B: The ratio of defective channels to the total number of channels is 5% or more and less than 10% C: The ratio of defective channels to the total number of channels is 10% or more.

[0212] The results are shown in Table 2 (Table 2-1 to Table 2-6).

[0213] [Table 2-1]

[0214] [Table 2-2]

[0215] [Table 2-3]

[0216] [Table 2-4]

[0217] [Table 2-5]

[0218] [Table 2-6]

[0219] As shown in Table 2, the magnetic tapes of the examples had smaller σPES values ​​and were superior in running stability compared to the magnetic tapes of the comparative examples. Furthermore, the magnetic tapes of the Examples exhibited excellent recording and reproduction performance (evaluation result: A or B) after being stored under an accelerated environment equivalent to long-term storage. These results confirm that the magnetic tapes of the Examples contributed to improving the operational stability of drives (magnetic tape devices). The inventors believe that the reasons why the magnetic tapes of the Examples exhibited excellent recording and reproduction performance are that the magnetic tapes of the Examples did not have a leader tape, that the Spc of the magnetic layer surface of the data tape was 0.30 (1 / μm) or more and 0.70 (1 / μm) or less, and that the standard deviation σ of Spc was 0.15 (1 / μm) or less.

[0220] A magnetic tape was prepared in the same manner as in Example 1, except that no vertical orientation treatment was performed during the preparation of the data tape. A sample piece was cut from the data tape portion of the magnetic tape. The squareness ratio of this sample piece in the vertical direction was measured using a Tamagawa Seisakusho TM-TRVSM5050-SMSL vibrating sample magnetometer according to the method described above, and was found to be 0.55. The squareness ratio in the vertical direction of a sample piece cut out from the magnetic tape of Example 1 was similarly determined and was found to be 0.65.

[0221] The two magnetic tapes were each attached to a 1 / 2-inch reel tester, and the electromagnetic conversion characteristics (SNR: Signal-to-Noise Ratio) were evaluated using the following method. As a result, the magnetic tape of Example 1 exhibited an SNR value 4 dB higher than that of the magnetic tape produced without vertical orientation treatment. Ten passes of recording and playback were performed in an environment with a temperature of 23°C and a relative humidity of 50%, applying a tension of 0.7 N (Newton) in the longitudinal direction of the magnetic tape. The relative speed between the magnetic tape and the magnetic head was 6 m / s. Recording was performed using a metal-in-gap (MIG) head (gap length 0.15 μm, track width 1.0 μm) as the recording head, with the recording current set to the optimal recording current for each magnetic tape. Playback was performed using a giant-magnetoresistive (GMR) head (element thickness 15 nm, shield spacing 0.1 μm, playback element width 0.8 μm) as the playback head. The head tilt angle was 0°. A signal with a linear recording density of 300 kfci was recorded, and the playback signal was measured using a Shibasoku spectrum analyzer. The unit kfci is the unit of linear recording density (not convertible to SI units). The signal was recorded from the point where the signal had stabilized sufficiently after the magnetic tape started running. [Industrial Applicability]

[0222] One aspect of the present invention is useful in various data storage technical fields.

Claims

1. A magnetic tape having a non-magnetic support and a magnetic layer containing ferromagnetic powder, The magnetic tape is a data tape having a leader pin attached directly to the end thereof, The friction force F against the LTO9 head measured at a head tilt angle of 10° in the edge region of the surface of the magnetic layer on the side where the leader pin is attached is １０° is 4 gf or more and 15 gf or less, The magnetic tape has a leader pin attachment end region that is a region ranging from 5 cm to 20 cm from the end of the leader pin attachment end of the data tape, which is the starting point 0 cm in the longitudinal direction.

2. The arithmetic mean curvature Spc of the peaks of the surface of the magnetic layer as defined in ISO 25178 is 0.30 (1 / μm) or more and 0.70 (1 / μm) or less, and 2. The magnetic tape according to claim 1, wherein the standard deviation σ of the Spc in the width direction of the surface of the magnetic layer is 0.15 (1 / μm) or less.

3. 2. The magnetic tape according to claim 1, wherein the magnetic layer further contains non-magnetic powder having an average tabular diameter of 50 nm to 1000 nm and an average tabular thickness of 12 nm or less.

4. 2. The magnetic tape of claim 1, wherein the data tape further comprises a non-magnetic layer between the non-magnetic support and the magnetic layer, the non-magnetic layer containing a non-magnetic powder.

5. The non-magnetic powder of the non-magnetic layer has an average particle volume of 2.0×10 －６ μm ３ 5. The magnetic tape according to claim 4, comprising the following Fe-based inorganic oxide powder:

6. 5. The magnetic tape according to claim 4, wherein the non-magnetic powder in the non-magnetic layer contains carbon black having a pH of 9.0 or less.

7. 5. The magnetic tape according to claim 4, wherein the thickness of the non-magnetic layer is 0.1 [mu]m or more and 0.7 [mu]m or less.

8. 2. The magnetic tape according to claim 1, wherein the data tape further comprises a backcoat layer containing non-magnetic powder on the surface of the non-magnetic support opposite to the surface having the magnetic layer.

9. 2. The magnetic tape of claim 1, wherein the data tape has a tape thickness of 5.2 [mu]m or less.

10. 2. The magnetic tape of claim 1, wherein the data tape has a tape thickness of 5.0 μm or less.

11. 2. The magnetic tape of claim 1, wherein the data tape has a squareness ratio in the perpendicular direction of 0.60 or greater.

12. 2. The magnetic tape of claim 1, wherein the data tape has a squareness ratio in the perpendicular direction of 0.65 or greater.

13. 2. The magnetic tape according to claim 1, wherein the end of the data tape to which the leader pin is directly attached further comprises a reinforcing layer on at least one of the magnetic layer side and the side opposite to the magnetic layer side.

14. 14. The magnetic tape according to claim 13, wherein the reinforcing layer has a thickness of 10.0 μm or more.

15. the arithmetic mean curvature Spc of the peaks of the surface of the magnetic layer as defined in ISO 25178 is 0.30 (1 / μm) or more and 0.70 (1 / μm) or less; the standard deviation σ of the Spc in the width direction of the surface of the magnetic layer is 0.15 (1 / μm) or less; the magnetic layer further contains non-magnetic powder having an average plate diameter of 50 nm or more and 1000 nm or less and an average plate thickness of 12 nm or less, the data tape further comprises a non-magnetic layer between the non-magnetic support and the magnetic layer, the non-magnetic layer containing a non-magnetic powder; The non-magnetic powder of the non-magnetic layer has an average particle volume of 2.0×10 －６ μm ３ The composition comprises the following Fe-based inorganic oxide powder and carbon black having a pH of 9.0 or less: the thickness of the nonmagnetic layer is 0.1 μm or more and 0.7 μm or less, the data tape further comprises a backcoat layer containing a nonmagnetic powder on a surface of the nonmagnetic support opposite to the surface having the magnetic layer; The data tape has a tape thickness of 5.0 μm or less, The data tape has a squareness ratio in the vertical direction of 0.65 or more, and 2. The magnetic tape according to claim 1, wherein the end of the data tape to which the leader pin is directly attached further comprises a reinforcing layer having a thickness of 10.0 μm or more on at least one of the magnetic layer side and the side opposite to the magnetic layer side.

16. A magnetic tape cartridge comprising the magnetic tape according to any one of claims 1 to 15.

17. A magnetic tape device comprising the magnetic tape according to any one of claims 1 to 15.

18. further comprising a magnetic head; the magnetic head has a module including an element array having a plurality of magnetic head elements between a pair of servo signal read elements; 18. The magnetic tape device according to claim 17, wherein the magnetic tape device changes an angle θ formed by an axis of the element array with respect to a width direction of the magnetic tape while the magnetic tape is running inside the magnetic tape device.

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