Magnetic tape, magnetic tape cartridge and magnetic tape device

Abstract

To provide a magnetic tape that can record and / or reproduce data excellently with a dimension in a width direction of the magnetic tape controlled by adjusting a tension to be applied in a longitudinal direction of the magnetic tape.SOLUTION: One embodiment of the present invention is a magnetic tape that satisfies TDSage+TDSenv-TC≤0.30 μm. One embodiment of the present invention is a magnetic tape cartridge and a magnetic tape device that include the magnetic tape. The TDSage is a maximum value of an absolute value of a differential between the servo band interval obtained prior to a prescribed storage and the servo band obtained after the storage. The TDSenv is a value to be calculated by multiplying a differential between a maximum value and minimum value in the servo band intervals obtained respectively under prescribed five environments with 1 / 2. The TC is a value to be calculated by multiplying TDStens with 0.5N, in which the TDStens is a ratio of a change in servo band interval with respect to a change in tension to be calculated from respective servo band intervals obtained respectively under the prescribed five environments by applying a plurality of different tensions in a longitudinal direction of the magnetic tape.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 include tape-type and disk-type recording media, and tape-type magnetic recording media, that is, magnetic tapes, are primarily used for data storage applications such as data backup and archiving (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6590102 specification Summary of the Invention [Problem to be solved by the invention]

[0004] Data is usually recorded on a magnetic tape by running the magnetic tape in a magnetic tape device (usually called a "drive") and recording data on the data band of the magnetic tape 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.

[0005] In order to improve the accuracy with which the magnetic head tracks the data band of the magnetic tape during the above-described recording and / or reproduction, a system that performs head tracking using a servo signal (hereinafter referred to as a "servo system") has been put into practical use. Furthermore, the width of the magnetic tape is controlled by acquiring width dimensional information of the magnetic tape while it is running using a servo signal, and adjusting the tension applied to the magnetic tape in the longitudinal direction according to the acquired width information (see paragraph 0171 of Patent Document 1 as an example). If, during recording or reproduction, the magnetic head for recording or reproducing data deviates from the target track position due to width deformation of the magnetic tape and records or reproduces data, phenomena such as overwriting of recorded data and reproduction failure occur. The present inventor believes that adjusting the tension as described above is an effective means for suppressing the occurrence of such phenomena.

[0006] In view of the above, one aspect of the present invention aims to provide a magnetic tape that can perform good recording and / or playback by controlling the width dimension of the magnetic tape by adjusting the tension applied to the magnetic tape in the longitudinal direction. [Means for solving the problem]

[0007] One aspect of the present invention is A non-magnetic support and a magnetic layer containing ferromagnetic powder, The magnetic layer has a plurality of servo bands, Formula 1 below: (Formula 1) TDSage+TDSenv-TC≦0.30μm Fulfilling In formula 1, TDSage is the maximum absolute value of the difference between the servo band intervals obtained before and after 24 hours of storage in an environment with a temperature of 60°C and a relative humidity of 20%, and is expressed in μm. TDSenv works in the following 5 environments: Temperature 16℃, relative humidity 20%, Temperature 16℃ Relative humidity 80%, Temperature 26℃, relative humidity 80%, Temperature 32℃, relative humidity 20%, Temperature 32℃, relative humidity 55%, This value is calculated by multiplying the difference between the maximum and minimum values ​​of the servo band intervals obtained in each of the above by 1 / 2, and is expressed in μm. TC is calculated by multiplying TDStens by 0.5N. TDStens applies different tensions to the magnetic tape in the longitudinal direction under the following five conditions: Temperature 16℃, relative humidity 20%, Temperature 16℃ Relative humidity 80%, Temperature 26℃, relative humidity 80%, Temperature 32℃, relative humidity 20%, Temperature 32℃, relative humidity 55%, This is the ratio of the change in servo band spacing to the change in tension, calculated from the servo band spacing obtained in each step, and is expressed in μm / N. Magnetic tape, Regarding.

[0008] In one embodiment, the magnetic tape can satisfy the following formula 1-1. (Formula 1-1) TDSage+TDSenv-TC≦0.05μm

[0009] In one embodiment, the magnetic tape may have a tape thickness of 5.6 μm or less.

[0010] In one embodiment, the magnetic tape may have a tape thickness of 5.3 μm or less.

[0011] In one embodiment, the magnetic tape can have a non-magnetic layer containing non-magnetic powder between the non-magnetic support and the magnetic layer.

[0012] In one embodiment, the magnetic tape can have a backcoat layer containing a nonmagnetic powder on the surface side of the nonmagnetic support opposite to the surface side having the magnetic layer.

[0013] In one embodiment, the non-magnetic support can be an aromatic polyester support.

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

[0015] In one form, the aromatic polyester support can be a polyethylene naphthalate support.

[0016] One aspect of the present invention relates to a magnetic tape cartridge including the above-mentioned magnetic tape.

[0017] One aspect of the present invention relates to a magnetic tape device including the above-mentioned magnetic tape cartridge.

[0018] In one embodiment, the tension applied to the magnetic tape in the longitudinal direction while the magnetic tape is running within the magnetic tape device can be variably adjusted.

[0019] In one embodiment, the tension can be adjusted in the range of 0.2N to 1.2N.

[0020] In one embodiment, the magnetic tape device can further include a magnetic head having a read element with a read element width of 0.8 μm or less. Effect of the Invention

[0021] According to one aspect of the present invention, it is possible to provide a magnetic tape that can control the width direction of the magnetic tape by adjusting the tension applied to the magnetic tape in the longitudinal direction, thereby enabling good recording and / or reproduction. Also, according to one aspect of the present invention, it is possible to provide a magnetic tape cartridge including the magnetic tape, and a magnetic tape device including the magnetic tape cartridge. [Brief description of the drawings]

[0022] [Figure 1] 2 shows an example of the arrangement of data bands and servo bands. [Diagram 2] An example of servo pattern arrangement on an LTO (Linear Tape-Open) Ultrium format tape is shown. [Diagram 3] FIG. 1 is a schematic diagram illustrating an example of a magnetic tape device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [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 layer having a plurality of servo bands and satisfying formula 1 above.

[0024] In a magnetic tape device that controls the width of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape, the greater the tension applied in the longitudinal direction of the magnetic tape, the greater the shrinkage of the width of the magnetic tape (i.e., the narrower it can be), and the smaller the tension, the smaller the degree of shrinkage. In this way, the width of the magnetic tape can be controlled by adjusting the tension applied in the longitudinal direction of the magnetic tape. In the course of repeated investigations to obtain a magnetic tape capable of controlling the widthwise dimensions of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape and performing good recording and / or reproduction, the inventors have noticed that the dimensional stability of the magnetic tape when tension is applied in the longitudinal direction of the tape can vary depending on the measurement environment. As a result of further intensive investigations, the inventors have come to use as an index the dimensional stability of the magnetic tape when tension is applied in the longitudinal direction of the tape, which is measured in various environments in which the magnetic tape may be placed during use and / or storage. These indexes are the above-mentioned TDSage and TDSenv. "TDS" is an abbreviation for "Tape Dimensional Stability," and "age" is an abbreviation for long-term storage. Also, "env" is an abbreviation for "environment." Also, in the TDStens described below, "tens" is an abbreviation for "tension." The inventor believes that "TDSage" in the formula 1 is a value obtained by the method described later, and can be an index of the amount of change in the servo band interval caused by long-term storage. The inventor believes that "TDSenv" is a value obtained by the method described later, and can be an index of the amount of change in the servo band interval caused by the usage environment. The inventor believes that "TC" can be an index of the amount of track position deviation that is permissible when recording and / or reproducing while adjusting the tension. After extensive research, the inventor has newly found that a magnetic tape whose "TDSage", "TDSenv" and "TC" satisfy the formula 1 is suitable as a magnetic tape for recording and / or reproducing in a magnetic tape device that controls the width dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape. For example, it has been newly found that a magnetic tape that satisfies the above formula 1 can contribute to enabling good recording and / or reproducing by controlling the width dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape after long-term storage. The magnetic tape will be further described in detail below. Hereinafter, the area sandwiched between two adjacent servo bands is referred to as a data band.

[0025] <Measurement method of TDSage> TDSage is obtained by the following method. A magnetic tape cartridge containing the magnetic tape to be measured is placed in an environment of 23°C ambient temperature and 50% relative humidity for 5 days in order to acclimatize the magnetic tape to the measurement environment. Thereafter, in a magnetic tape apparatus having a tension adjusting mechanism for applying tension in the longitudinal direction of the magnetic tape under the measurement environment, the magnetic tape is run with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. Regarding such running, the interval between two adjacent servo bands sandwiching the data band is measured at 1 m intervals over the entire length of the magnetic tape. In the measurement for obtaining TDSage, TDSenv and TC described in the present invention and this specification, the value of the tension applied in the longitudinal direction of the magnetic tape shall be the set value set in the magnetic tape apparatus. Also, in the present invention and this specification, "measured at 1 m intervals" means that for a measurement target area with a length of L meters (m), the position of one end of the measurement target area is 0 m, and each position in the direction towards the other end is 1 m, 2 m, 3 m ···, and when the position of the other end is Lm, the first measurement position is the position of 1 m, and the last measurement position is the position one before the position of Lm. Also, when there are a plurality of servo band intervals, the servo band intervals are measured in the same manner for all servo band intervals. The servo band interval measured in this way is defined as the "pre-storage servo band interval" at each measurement position. Thereafter, the magnetic tape cartridge is stored in a storage environment of 60°C ambient temperature and 20% relative humidity for 24 hours. The present inventor believes that this storage may correspond to long-term storage for about 10 years in an environment of 32°C ambient temperature and 55% relative humidity. After such storage, the magnetic tape cartridge is placed in a measurement environment of an ambient temperature of 23°C and a relative humidity of 50% for 5 days, and then in the same measurement environment, in a magnetic tape device having a tension adjustment mechanism for applying tension in the longitudinal direction of the magnetic tape, the magnetic tape is run with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. For such running, the servo band interval is measured in the same manner as the method described above. The servo band interval thus measured is taken as the "servo band interval after storage" at each measurement position. For all servo band intervals, the difference between the servo band interval before storage and the servo band interval after storage measured at 1 m intervals is obtained. Thus, a plurality of difference values are obtained. The maximum value of the absolute value of the obtained differences is taken as the "TDSage" of the magnetic tape to be measured. The interval between two adjacent servo bands sandwiching the data band can be obtained, for example, using the PES (Position Error Signal) obtained from the servo signal obtained by reading the servo pattern by the servo signal reading element. For details, reference can be made to the description of the examples below.

[0026] <Measurement method of TDSenv> TDSenv is obtained by the following method. For each measurement environment, the magnetic tape cartridge containing the magnetic tape to be measured is placed in the measurement environment for 5 days in order to acclimatize it to the measurement environment. The measurement environments are the 5 environments described above (i.e., temperature 16°C, relative humidity 20%, temperature 16°C, relative humidity 80%, temperature 26°C, relative humidity 80%, temperature 32°C, relative humidity 20%, temperature 32°C, relative humidity 55%). After that, in a magnetic tape device having a tension adjusting mechanism for applying tension in the longitudinal direction of the magnetic tape under the measurement environment, the magnetic tape is run with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. For the magnetic tape, the end on the side wound around the reel of the magnetic tape cartridge is called the inner end, and the end on the opposite side is called the outer end. With the outer end set to 0 m, in the region spanning a length of 0 m to 100 m (hereinafter referred to as the "100 m region on the outer periphery of the reel"), at intervals of 1 m, for the above running, in data band 0 (zero), the servo band interval is measured at intervals of 1 m. "Data band 0" is a data band defined as the data band where data embedding (recording) is first performed according to the standard. The arithmetic mean of the measured servo band intervals is taken as the servo band interval in that measurement environment. After obtaining the servo band interval in each of the above five environments as described above, using the maximum value and the minimum value among the obtained values, the value calculated as "(maximum value - minimum value) × 1 / 2" is taken as the "TDSenv" of the magnetic tape to be measured.

[0027] <Measurement method of TC> TC is obtained by the following method. For each measurement environment, the magnetic tape cartridge containing the magnetic tape to be measured is placed in the measurement environment for 5 days in order to acclimatize it to the measurement environment. The measurement environments are the five environments described above (i.e., temperature 16°C, relative humidity 20%, temperature 16°C, relative humidity 80%, temperature 26°C, relative humidity 80%, temperature 32°C, relative humidity 20%, temperature 32°C, relative humidity 55%). After that, in a magnetic tape device having a tension adjusting mechanism for applying tension in the longitudinal direction of the magnetic tape under the measurement environment, the following measurements are performed. The magnetic tape is run with a tension of 0.2 N applied in the longitudinal direction of the magnetic tape. For such running, in the 100 m region on the outer periphery of the reel at intervals of 1 m, in data band 0 (zero), the servo band interval is measured. The arithmetic mean of the measured servo band intervals is taken as "G 0.2N ". G 0.2NAfter measuring the servo band interval, the tension applied to the magnetic tape in the longitudinal direction is increased to 0.4N, and the servo band interval is measured in the same manner as above while the tension of 0.4N is applied. The arithmetic mean of the measured servo band interval is calculated as "G 0.4N " G 0.4N After measuring the tension in the longitudinal direction of the magnetic tape, increase the tension to 0.6N, and measure the servo band interval in the same manner as above while applying a tension of 0.6N. The arithmetic mean of the measured servo band intervals is called "G 0.6N " G 0.6N After measuring the servo band interval, increase the tension applied to the magnetic tape in the longitudinal direction to 0.8N, and measure the servo band interval in the same manner as above while applying a tension of 0.8N. The measured servo band interval is calculated as "G 0.8N " G 0.8N After measuring the servo band interval, increase the tension applied to the magnetic tape in the longitudinal direction to 1.0 N, and measure the servo band interval in the same manner as above while applying a tension of 1.0 N. The arithmetic average of the measured servo band intervals is called "G 1.0N " G 1.0N After measuring the servo band interval, the tension applied to the magnetic tape in the longitudinal direction is increased to 1.2N, and the servo band interval is measured in the same manner as above while the tension of 1.2N is applied. The arithmetic mean of the measured servo band interval is calculated as "G 1.2N " G 0.2N , G 0.4N , G 0.6N , G 0.8N , G 1.0N and G 1.2N The measurements should be performed within 5 minutes of each other, and measurements at each tension should begin within 5 minutes of the end of the measurement at the previous tension. The G calculated by the above method 0.2N , G 0.4N , G 0.6N , G 0.8N , G 1.0N and G 1.2NThe ratio of change in servo band spacing to change in tension is calculated for the linear function Y=AX+B (A is the slope, B is the intercept) where X is tension and Y is the servo band spacing calculated with each tension applied (i.e., the above arithmetic average calculated from each measurement).The absolute value of the slope A obtained by the least squares method is taken as the ratio of change in servo band spacing to change in tension in the measurement environment, "TDStens". The above measurements are carried out in the five environments. In this way, "TDStens", which is the ratio of change in servo band spacing to change in tension in the five environments, is calculated. The minimum TDStens value calculated in each of the five environments is adopted as the "TDStens" value for calculating the TC of the magnetic tape being measured, and this TDStens value (unit: μm / N) is multiplied by 0.5N, i.e., the value calculated as "TDStens x 0.5" is used as the "TC" of the magnetic tape being measured.

[0028] <Expression 1> Equation 1 is as follows: (Formula 1) TDSage+TDSenv-TC≦0.30μm

[0029] The method for measuring "TDSage", "TDSenv" and "TC" to obtain formula 1 is as described above. When determining these three values ​​for the magnetic tape to be measured, "TDSage" is measured first. Thereafter, when measuring "TDSenv" and "TC", there is no particular restriction on the order in which the measurements are performed, and either may be measured first.

[0030] The magnetic tape satisfies formula 1. As a result of intensive research by the present inventor, it has been newly found that the magnetic tape that satisfies formula 1 is suitable as a magnetic tape for recording and / or reproducing in a magnetic tape device that controls the width dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape. In detail, the magnetic tape can contribute to enabling good recording and / or reproducing by controlling the width dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape after long-term storage. From this point of view, the value of the left side of formula 1 is 0.30 μm or less, preferably 0.25 μm or less, more preferably 0.20 μm or less, even more preferably 0.15 μm or less, even more preferably 0.10 μm or less, even more preferably 0.05 μm or less, and even more preferably 0.00 μm or less. In one embodiment, the magnetic tape can satisfy formula 1-1 described above. Furthermore, from the viewpoint of process suitability when manufacturing the magnetic tape, the left side of formula 1 is preferably -1.00 μm or more, more preferably -0.90 μm or more, even more preferably -0.80 μm or more, even more preferably -0.70 μm or more, and even more preferably -0.60 μm or more.

[0031] Regarding formula 1, the value on the left side of formula 1 can be adjusted depending on, for example, the thickness of the magnetic tape, the strength of the nonmagnetic support (e.g., Young's modulus), the moisture content of the nonmagnetic support, the manufacturing conditions of the magnetic tape, etc. For this point, the description below can also be referred to.

[0032] The magnetic tape is only required to satisfy formula 1, and the values ​​of TDSage, TDSenv and TC are not particularly limited.

[0033] In one embodiment, the TDSage can be 0.00 μm or more, more than 0.00 μm, 0.05 μm or more, 0.10 μm or more, or 0.30 μm or more, and can be 3.00 μm or less, 2.50 μm or less, 2.00 μm or less, or 1.50 μm or less. The TDSage can be adjusted, for example, by the manufacturing conditions of the magnetic tape.

[0034] In one embodiment, TDSenv can be 0.00 μm or more, more than 0.00 μm, 0.05 μm or more, or 0.10 μm or more, and can be 2.00 μm or less, 1.50 μm or less, or 1.00 μm or less. TDSenv can be adjusted, for example, by the strength (e.g., Young's modulus) of the non-magnetic support, the moisture content of the non-magnetic support, etc.

[0035] In one embodiment, TC can be 0.00 μm or more, more than 0.00 μm, 0.10 μm or more, 0.30 μm or more, or 0.50 μm or more, and can be 3.00 μm or less, 2.50 μm or less, 2.00 μm or less, or 1.50 μm or less. In one embodiment, TDStens can be 0.00 μm / N or more, more than 0.00 μm / N, 0.20 μm / N or more, 0.60 μm / N or more, or 1.00 μm / N or more, and can be 6.00 μm / N or less, 5.00 μm / N or less, 4.00 μm or less, or 3.00 μm or less. TC and TDStens can be adjusted, for example, depending on the thickness of the magnetic tape.

[0036] <Nonmagnetic support> 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 and polyethylene naphthalate are preferred.

[0037] In one embodiment, the non-magnetic support of the magnetic tape may be an aromatic polyester support. In the present invention and this specification, "aromatic polyester" means a resin containing an aromatic skeleton and a plurality of ester bonds, and "aromatic polyester support" means a support containing at least one layer of aromatic polyester film. "Aromatic polyester film" means a film in which the component that constitutes this film in the largest proportion by mass is an aromatic polyester. In the present invention and this specification, the "aromatic polyester support" includes a support in which all the resin films contained in this support are aromatic polyester films, and a support containing an aromatic polyester film and another resin film. Specific embodiments of the aromatic polyester support include a single-layer aromatic polyester film, a laminated film of two or more layers of aromatic polyester films having the same constituent components, a laminated film of two or more layers of aromatic polyester films having different constituent components, a laminated film containing one or more layers of aromatic polyester films and one or more layers of resin films other than aromatic polyesters, and the like. In the laminated film, an adhesive layer or the like may be optionally included between two adjacent layers. In addition, the aromatic polyester support may optionally include a metal film and / or a metal oxide film formed by deposition or the like on one or both surfaces. The above also applies to the "polyethylene terephthalate support" and the "polyethylene naphthalate support" in the present invention and this specification.

[0038] The aromatic ring contained in the aromatic skeleton of the aromatic polyester is not particularly limited, but specific examples of the aromatic ring include a benzene ring and a naphthalene ring. For example, polyethylene terephthalate (PET) is a polyester containing a benzene ring, and is a resin obtained by polycondensation of ethylene glycol with terephthalic acid and / or dimethyl terephthalate. In the present invention and this specification, "polyethylene terephthalate" also includes structures having one or more other components (e.g., copolymerized components, components introduced into the terminals or side chains, etc.) in addition to the above components. Polyethylene naphthalate (PEN) is a polyester containing a naphthalene ring, and is a resin obtained by esterification of dimethyl 2,6-naphthalenedicarboxylate with ethylene glycol, followed by transesterification and polycondensation. In the present invention and this specification, "polyethylene naphthalate" also includes structures having one or more other components (e.g., copolymer components, components introduced into the terminals or side chains, etc.) in addition to the above components.

[0039] The non-magnetic support may be a biaxially stretched film, and may be a film that has been subjected to corona discharge, plasma treatment, easy-adhesion treatment, heat treatment, or the like.

[0040] An example of an index of the physical properties of a non-magnetic support is the moisture content. In the present invention and this specification, the moisture content of a non-magnetic support is a value determined by the following method. The moisture contents shown in the table below are values ​​determined by the following method. A sample piece (e.g., a sample piece having a mass of several grams) cut out from the non-magnetic support for which moisture content is to be measured is dried until it reaches a constant weight in a vacuum dryer at a temperature of 180° C. and a pressure of 100 Pa (pascals) or less. The mass of the sample piece thus dried is designated as W1. W1 is a value measured in a measurement environment at a temperature of 23° C. and a relative humidity of 50% within 30 seconds after it is removed from the vacuum dryer. Next, W2 is the mass of the sample piece after it is placed in an environment at a temperature of 25° C. and a relative humidity of 75% for 48 hours. W2 is a value measured in a measurement environment at a temperature of 23° C. and a relative humidity of 50% within 30 seconds after it is removed from the environment. The moisture content is calculated by the following formula. Moisture content (%)=[(W2-W1) / W1]×100 For example, after removing the portions other than the non-magnetic support, such as the magnetic layer, from the magnetic tape by a known method (such as removal of the film using an organic solvent), the water content of the non-magnetic support can be determined by the above method.

[0041] In one embodiment, the non-magnetic support of the magnetic tape preferably has a moisture content of 1.0% or less, more preferably 0.8% or less, and even more preferably 0.6% or less. The moisture content of the non-magnetic support of the magnetic tape may be 0%, 0% or more, more than 0%, or 0.1% or more. By using a non-magnetic support with a low moisture content, the TDSenv value tends to be smaller.

[0042] An example of an index of the physical properties of a non-magnetic support is Young's modulus. In the present invention and this specification, the Young's modulus of a non-magnetic support is a value measured by the following method in a measurement environment at a temperature of 23°C and a relative humidity of 50%. The Young's moduli shown in the table below are values ​​obtained by the following method using a Tensilon manufactured by Toyo Baldwin Co., Ltd. as a universal tensile testing device. A sample piece cut out from the non-magnetic support to be measured is pulled by a universal tensile tester under the conditions of a chuck distance of 100 mm, a pulling speed of 10 mm / min, and a chart speed of 500 mm / min. As the universal tensile tester, for example, a commercially available universal tensile tester such as Toyo Baldwin's Tensilon or a universal tensile tester of a known configuration can be used. From the tangent of the rising part of the load-elongation curve thus obtained, the Young's modulus in the longitudinal direction and the width direction of the sample piece are calculated. Here, the longitudinal direction and the width direction of the sample piece refer to the longitudinal direction and the width direction when the sample piece is included in a magnetic tape. For example, after removing the portions other than the non-magnetic support, such as the magnetic layer, from the magnetic tape by a known method (e.g., removal using an organic solvent), the Young's modulus in the longitudinal and transverse directions of the non-magnetic support can be determined by the above method.

[0043] In one embodiment, the non-magnetic support of the magnetic tape preferably has a Young's modulus in the longitudinal direction of 3000 MPa or more, more preferably 4000 MPa or more, and even more preferably 5000 MPa or more. The Young's modulus in the longitudinal direction of the non-magnetic support of the magnetic tape can be 15000 MPa or less, 13000 MPa or less, 11000 MPa or less, or 9000 MPa or less. In the width direction, the non-magnetic support of the magnetic tape preferably has a Young's modulus in the width direction of 2000 MPa or more, more preferably 3000 MPa or more, and even more preferably 4000 MPa or more. The Young's modulus in the width direction of the non-magnetic support of the magnetic tape can be 10000 MPa or less, 8000 MPa or less, or 6000 MPa or less. When manufacturing a magnetic tape, the non-magnetic support is usually used with the MD direction (machine direction) of the film as the longitudinal direction and the TD direction (transverse direction) as the width direction. In one embodiment, the Young's modulus in the longitudinal direction is preferably larger than the Young's modulus in the width direction, and the difference (Young's modulus in the longitudinal direction - Young's modulus in the width direction) is more preferably in the range of 800 to 3000 MPa.

[0044] The water content and Young's modulus of the nonmagnetic support can be controlled by the types and mixing ratios of the components constituting the support, the manufacturing conditions of the support, etc. For example, by adjusting the stretching ratio in each direction in the biaxial stretching process, the Young's modulus in the longitudinal direction and the Young's modulus in the transverse direction can be controlled, respectively.

[0045] <Magnetic layer> (Ferromagnetic powder) As the ferromagnetic powder contained in the magnetic layer, one or more of the ferromagnetic powders known as ferromagnetic powders used in the magnetic layers of various magnetic recording media can be used in combination. It is preferable to use a ferromagnetic powder with a small average particle size from the viewpoint of improving recording density. From this viewpoint, the average particle size of the ferromagnetic powder is preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less, even more preferably 35 nm or less, even more preferably 30 nm or less, even more preferably 25 nm or less, and even more preferably 20 nm or less. On the other hand, from the viewpoint of magnetization stability, the average particle size of the ferromagnetic powder is preferably 5 nm or more, more preferably 8 nm or more, even more preferably 10 nm or more, even more preferably 15 nm or more, and even more preferably 20 nm or more.

[0046] Hexagonal Ferrite Powder A preferred specific example of the ferromagnetic powder is hexagonal ferrite powder. For details of the hexagonal ferrite powder, see, for example, JP2011-225417A, paragraphs 0012-0030, JP2011-216149A, paragraphs 0134-0136, JP2012-204726A, paragraphs 0013-0030, and JP2015-127985A, paragraphs 0029-0084.

[0047] In the present invention and this specification, the term "hexagonal ferrite powder" refers to a ferromagnetic powder in which a hexagonal ferrite type crystal structure is detected as the main phase by X-ray diffraction analysis. The main phase refers to a structure to which the most intense diffraction peak belongs in the X-ray diffraction spectrum obtained by X-ray diffraction analysis. For example, when the most intense diffraction peak in the X-ray diffraction spectrum obtained by X-ray diffraction analysis is assigned to a hexagonal ferrite type crystal structure, it is determined that the hexagonal ferrite type crystal structure has been detected as the main phase. When only a single structure is detected by X-ray diffraction analysis, the detected structure is regarded as the main phase. The hexagonal ferrite type crystal structure contains at least an iron atom, a divalent metal atom, and an oxygen atom as constituent atoms. The divalent metal atom is a metal atom that can become a divalent cation as an ion, and examples of such include alkaline earth metal atoms such as strontium atoms, barium atoms, and calcium atoms, and lead atoms. In the present invention and this specification, the hexagonal strontium ferrite powder refers to a powder in which the main divalent metal atom contained therein is a strontium atom, and the hexagonal barium ferrite powder refers to a powder in which the main divalent metal atom contained therein is a barium atom. The main divalent metal atom refers to the divalent metal atom that is the most abundant of the divalent metal atoms contained in the powder on an atomic % basis. However, the above divalent metal atoms do not include rare earth atoms. In the present invention and this specification, the "rare earth atom" is selected from the group consisting of scandium atoms (Sc), yttrium atoms (Y), and lanthanoid atoms. The lanthanide atom is selected from the group consisting of a lanthanum atom (La), a cerium atom (Ce), a praseodymium atom (Pr), a neodymium atom (Nd), a promethium atom (Pm), a samarium atom (Sm), a europium atom (Eu), a gadolinium atom (Gd), a terbium atom (Tb), a dysprosium atom (Dy), a holmium atom (Ho), an erbium atom (Er), a thulium atom (Tm), a ytterbium atom (Yb), and a lutetium atom (Lu).

[0048] Hereinafter, hexagonal strontium ferrite powder, which is one form of hexagonal ferrite powder, will be described in more detail.

[0049] The activation volume of the hexagonal strontium ferrite powder is preferably 800 to 1600 nm 3 The finely divided hexagonal strontium ferrite powder having an activation volume in the above range is suitable for producing a magnetic tape exhibiting excellent electromagnetic conversion characteristics. The activation volume of the hexagonal strontium ferrite powder is preferably 800 nm 3 For example, 850 nm or more. 3 From the viewpoint of further improving the electromagnetic conversion characteristics, the activation volume of the hexagonal strontium ferrite powder can be 1500 nm or more. 3 More preferably, it is 1400 nm or less. 3 More preferably, it is 1300 nm or less. 3 More preferably, it is 1200 nm or less. 3 More preferably, it is equal to or less than 1100 nm. 3 It is even more preferable that the activation volume of the hexagonal barium ferrite powder is equal to or less than 1000 nm. The same is true for the activation volume of the hexagonal barium ferrite powder.

[0050] "Activation volume" is a unit of magnetization reversal and is an index showing the magnetic size of a particle. The activation volume and the anisotropy constant Ku described in the present invention and this specification are values ​​obtained by measuring the coercive force Hc measurement section at magnetic field sweep speeds of 3 minutes and 30 minutes (measurement temperature: 23°C ± 1°C) using a vibrating sample magnetometer, and calculating from the following relationship between Hc and activation volume V. The unit of the anisotropy constant Ku is 1 erg / cc = 1.0 x 10 -1 J / m 3 It is. Hc=2Ku / Ms{1-[(kT / KuV)ln(At / 0.693)] 1 / 2} [In the above formula, Ku: anisotropy constant (unit: J / m 3 ), Ms: saturation magnetization (unit: kA / m), k: Boltzmann constant, T: absolute temperature (unit: K), V: activation volume (unit: cm 3), A: spin precession frequency (unit: s -1 ), t: magnetic field reversal time (unit: s)]

[0051] The anisotropy constant Ku can be used as an index of reduction in thermal fluctuation, in other words, improvement in thermal stability. The hexagonal strontium ferrite powder is preferably 1.8×10 5 J / m 3 More preferably, the Ku is 2.0×10 or more. 5 J / m 3 The Ku of the hexagonal strontium ferrite powder can be, for example, 2.5×10 5 J / m 3 However, since a higher Ku value means higher thermal stability and is preferable, the Ku value is not limited to the above-mentioned values.

[0052] The hexagonal strontium ferrite powder may or may not contain rare earth atoms. When the hexagonal strontium ferrite powder contains rare earth atoms, it is preferable that the rare earth atoms are contained at a content (bulk content) of 0.5 to 5.0 atomic % relative to 100 atomic % of iron atoms. In one embodiment, the hexagonal strontium ferrite powder containing rare earth atoms can have uneven distribution of rare earth atoms in the surface layer portion. In the present invention and this specification, the term "surface distribution of rare earth atoms" refers to the rare earth atom content relative to 100 atomic % of iron atoms in a solution obtained by partially dissolving a hexagonal strontium ferrite powder in an acid (hereinafter referred to as "surface content of rare earth atoms" or simply "surface content" for rare earth atoms), which is greater than the rare earth atom content relative to 100 atomic % of iron atoms in a solution obtained by completely dissolving a hexagonal strontium ferrite powder in an acid (hereinafter referred to as "bulk content of rare earth atoms" or simply "bulk content" for rare earth atoms), Rare earth atom surface content / rare earth atom bulk content>1.0 The rare earth atom content of the hexagonal strontium ferrite powder described later is synonymous with the rare earth atom bulk content. In contrast, partial dissolution using an acid dissolves the surface layer of the particles constituting the hexagonal strontium ferrite powder, so the rare earth atom content in the solution obtained by partial dissolution is the rare earth atom content in the surface layer of the particles constituting the hexagonal strontium ferrite powder. The rare earth atom surface layer content satisfying the ratio of "rare earth atom surface layer content / rare earth atom bulk content>1.0" means that the rare earth atoms are unevenly distributed (i.e., more present in the surface layer) in the particles constituting the hexagonal strontium ferrite powder. In the present invention and this specification, the surface layer refers to a portion of the region extending from the surface of the particles constituting the hexagonal strontium ferrite powder toward the inside.

[0053] When the hexagonal strontium ferrite powder contains rare earth atoms, the rare earth atom content (bulk content) is preferably in the range of 0.5 to 5.0 atomic % relative to 100 atomic % of iron atoms. It is considered that the rare earth atoms contained in the bulk content in the above range and the rare earth atoms unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder contribute to suppressing the decrease in the reproduction output during repeated reproduction. This is presumed to be because the hexagonal strontium ferrite powder contains rare earth atoms in the bulk content in the above range and the rare earth atoms unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder can increase the anisotropy constant Ku. The higher the value of the anisotropy constant Ku, the more the occurrence of a phenomenon called thermal fluctuation can be suppressed (in other words, the thermal stability can be improved). By suppressing the occurrence of thermal fluctuation, the decrease in the reproduction output during repeated reproduction can be suppressed. It is speculated that the uneven distribution of rare earth atoms in the surface layer of hexagonal strontium ferrite powder particles contributes to stabilizing the spin of the iron (Fe) sites in the crystal lattice of the surface layer, thereby increasing the anisotropy constant Ku. In addition, it is presumed that using the hexagonal strontium ferrite powder having rare earth atom uneven distribution on the surface as the ferromagnetic powder of the magnetic layer also contributes to suppressing the wear of the magnetic layer surface due to sliding with the magnetic head. That is, it is presumed that the hexagonal strontium ferrite powder having rare earth atom uneven distribution on the surface can also contribute to improving the running durability of the magnetic tape. This is presumed to be because the uneven distribution of rare earth atoms on the surface of the particles constituting the hexagonal strontium ferrite powder contributes to improving the interaction between the particle surface and the organic substance (e.g., binder and / or additive) contained in the magnetic layer, and as a result, the strength of the magnetic layer is improved. From the viewpoint of further suppressing the decrease in regeneration output during repeated regeneration and / or further improving running durability, the rare earth atom content (bulk content) is more preferably in the range of 0.5 to 4.5 atomic %, even more preferably in the range of 1.0 to 4.5 atomic %, and even more preferably in the range of 1.5 to 4.5 atomic %.

[0054] The bulk content is the content obtained by completely dissolving the hexagonal strontium ferrite powder. In the present invention and this specification, unless otherwise specified, the content of an atom refers to the bulk content obtained by completely dissolving the hexagonal strontium ferrite powder. The hexagonal strontium ferrite powder containing rare earth atoms may contain only one rare earth atom as a rare earth atom, or may contain two or more rare earth atoms. When two or more rare earth atoms are contained, the bulk content is obtained for the total of two or more rare earth atoms. This point is the same for other components in the present invention and this specification. That is, unless otherwise specified, a certain component may be used in only one type or in two or more types. When two or more types are used, the content or content refers to the total of two or more types.

[0055] When the hexagonal strontium ferrite powder contains rare earth atoms, the rare earth atoms contained therein may be any one or more of rare earth atoms. From the viewpoint of further suppressing the decrease in the reproduction output during repeated reproduction, preferred rare earth atoms include neodymium atoms, samarium atoms, yttrium atoms and dysprosium atoms, more preferred are neodymium atoms, samarium atoms and yttrium atoms, and even more preferred are neodymium atoms.

[0056] In the hexagonal strontium ferrite powder having rare earth atom uneven distribution in the surface layer, the rare earth atoms may be unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder, and the degree of uneven distribution is not limited. For example, for the hexagonal strontium ferrite powder having rare earth atom uneven distribution in the surface layer, the ratio of the surface content of rare earth atoms obtained by partial dissolution under the dissolution conditions described below to the bulk content of rare earth atoms obtained by complete dissolution under the dissolution conditions described below, "surface content / bulk content", is more than 1.0 and can be 1.5 or more. The "surface content / bulk content" being greater than 1.0 means that the rare earth atoms are unevenly distributed in the surface layer (i.e., more than in the interior) in the particles constituting the hexagonal strontium ferrite powder. In addition, the ratio of the surface layer content of rare earth atoms obtained by partial dissolution under the dissolution conditions described later to the bulk content of rare earth atoms obtained by total dissolution under the dissolution conditions described later, "surface layer content / bulk content", can be, for example, 10.0 or less, 9.0 or less, 8.0 or less, 7.0 or less, 6.0 or less, 5.0 or less, or 4.0 or less. However, in a hexagonal strontium ferrite powder having rare earth atom surface layer uneven distribution, it is sufficient that the rare earth atoms are unevenly distributed in the surface layer of the particles constituting the hexagonal strontium ferrite powder, and the above "surface layer content / bulk content" is not limited to the upper or lower limit exemplified.

[0057] The partial and total dissolution of hexagonal strontium ferrite powder will be described below. For hexagonal strontium ferrite powder present as powder, the sample powders to be partially and completely dissolved are taken from the same lot of powder. On the other hand, for hexagonal strontium ferrite powder contained in the magnetic layer of a magnetic tape, a part of the hexagonal strontium ferrite powder taken out from the magnetic layer is subjected to partial dissolution, and the other part is subjected to total dissolution. The hexagonal strontium ferrite powder can be taken out from the magnetic layer by, for example, the method described in paragraph 0032 of JP 2015-91747 A. The above-mentioned partial dissolution means that the hexagonal strontium ferrite powder is dissolved to such an extent that the remaining powder can be visually confirmed in the liquid at the end of dissolution. For example, the partial dissolution can dissolve a region of 10 to 20 mass% of the particles constituting the hexagonal strontium ferrite powder, with the whole particles being 100 mass%. On the other hand, the above-mentioned complete dissolution means that the hexagonal strontium ferrite powder is dissolved to such an extent that the remaining powder cannot be visually confirmed in the liquid at the end of dissolution. The partial dissolution and the surface layer content are measured, for example, by the following method. Note that the dissolution conditions such as the amount of sample powder are merely examples, and any dissolution conditions that allow partial or complete dissolution can be used. A container (e.g., a beaker) containing 12 mg of sample powder and 10 mL of 1 mol / L hydrochloric acid is placed on a hot plate set at 70°C for 1 hour. The resulting solution is filtered through a 0.1 μm membrane filter. Elemental analysis of the filtrate thus obtained is performed using an inductively coupled plasma (ICP) analyzer. In this way, the surface layer content of rare earth atoms relative to 100 atomic % of iron atoms can be determined. When multiple types of rare earth atoms are detected by elemental analysis, the total content of all rare earth atoms is taken as the surface layer content. This is also true for the measurement of bulk content. On the other hand, the total dissolved and bulk contents are measured, for example, by the following method. A container (e.g., a beaker) containing 12 mg of sample powder and 10 mL of 4 mol / L hydrochloric acid is placed on a hot plate set at 80° C. for 3 hours. After that, the bulk content relative to 100 atomic % of iron atoms can be calculated by carrying out the same procedure as the partial dissolution and surface layer content measurement described above.

[0058] From the viewpoint of increasing the reproduction output when reproducing data recorded on a magnetic tape, it is desirable for the mass magnetization σs of the ferromagnetic powder contained in the magnetic tape to be high. In this regard, hexagonal strontium ferrite powder that contains rare earth atoms but does not have uneven distribution of rare earth atoms in the surface layer has a tendency to have a significantly lower σs than hexagonal strontium ferrite powder that does not contain rare earth atoms. In contrast, hexagonal strontium ferrite powder that has uneven distribution of rare earth atoms in the surface layer is considered to be preferable in terms of suppressing such a large decrease in σs. In one embodiment, the σs of the hexagonal strontium ferrite powder is 45 A·m 2 / kg or more, and 47A·m 2 / kg or more. On the other hand, from the viewpoint of noise reduction, σs is 80A·m 2 / kg or less, and 60A·m 2 / kg or less. σs can be measured using a known measuring device capable of measuring magnetic properties, such as a vibrating sample magnetometer. In the present invention and this specification, unless otherwise specified, the mass magnetization σs is a value measured at a magnetic field strength of 15 kOe. 1 [kOe]=10 6 / 4π[A / m].

[0059] Regarding the content (bulk content) of the constituent atoms of the hexagonal strontium ferrite powder, the strontium atom content can be, for example, in the range of 2.0 to 15.0 atomic % relative to 100 atomic % of iron atoms. In one embodiment, the divalent metal atoms contained in the hexagonal strontium ferrite powder can be only strontium atoms. In another embodiment, the hexagonal strontium ferrite powder can also contain one or more other divalent metal atoms in addition to strontium atoms. For example, it can contain barium atoms and / or calcium atoms. When divalent metal atoms other than strontium atoms are contained, the barium atom content and calcium atom content in the hexagonal strontium ferrite powder can each be, for example, in the range of 0.05 to 5.0 atomic % relative to 100 atomic % of iron atoms.

[0060] Known crystal structures of hexagonal ferrite include magnetoplumbite type (also called "M type"), W type, Y type, and Z type. The hexagonal strontium ferrite powder may have any of the crystal structures. The crystal structure can be confirmed by X-ray diffraction analysis. The hexagonal strontium ferrite powder may be one in which a single crystal structure or two or more types of crystal structures are detected by X-ray diffraction analysis. For example, in one embodiment, the hexagonal strontium ferrite powder may be one in which only the M-type crystal structure is detected by X-ray diffraction analysis. For example, M-type hexagonal ferrite is AFe 12 O 19Here, A represents a divalent metal atom, and when the hexagonal strontium ferrite powder is of the M type, A is only a strontium atom (Sr), or when A contains a plurality of divalent metal atoms, the strontium atom (Sr) accounts for the largest proportion on an atomic % basis as described above. The divalent metal atom content of the hexagonal strontium ferrite powder is usually determined by the type of crystal structure of the hexagonal ferrite, and is not particularly limited. The same applies to the iron atom content and the oxygen atom content. The hexagonal strontium ferrite powder contains at least an iron atom, a strontium atom, and an oxygen atom, and may further contain a rare earth atom. Furthermore, the hexagonal strontium ferrite powder may or may not contain atoms other than these atoms. As an example, the hexagonal strontium ferrite powder may contain an aluminum atom (Al). The content of aluminum atoms can be, for example, 0.5 to 10.0 atomic % relative to 100 atomic % of iron atoms. From the viewpoint of further suppressing the decrease in the reproduction output during repeated reproduction, the hexagonal strontium ferrite powder contains iron atoms, strontium atoms, oxygen atoms, and rare earth atoms, and the content of atoms other than these atoms is preferably 10.0 atomic % or less, more preferably in the range of 0 to 5.0 atomic %, relative to 100 atomic % of iron atoms, and may be 0 atomic %. That is, in one embodiment, the hexagonal strontium ferrite powder may not contain atoms other than iron atoms, strontium atoms, oxygen atoms, and rare earth atoms. The content expressed in atomic % above is obtained by converting the content (unit: mass %) of each atom obtained by completely dissolving the hexagonal strontium ferrite powder into a value expressed in atomic % using the atomic weight of each atom. In addition, in the present invention and this specification, "not containing" a certain atom means that the content measured by an ICP analyzer after completely dissolving is 0 mass %. The detection limit of an ICP analyzer is usually 0.01 ppm (parts per million) or less on a mass basis. The above term "free" is used to mean that the content is below the detection limit of the ICP analyzer.In one form, the hexagonal strontium ferrite powder can be one that does not contain bismuth atoms (Bi).

[0061] metal powder A specific preferred example of the ferromagnetic powder is a ferromagnetic metal powder. For details of the ferromagnetic metal powder, reference can be made to, for example, paragraphs 0137 to 0141 of JP 2011-216149 A and paragraphs 0009 to 0023 of JP 2005-251351 A.

[0062] ε-iron oxide powder A preferred specific example of the ferromagnetic powder is ε-iron oxide powder. In the present invention and this specification, the term "ε-iron oxide powder" refers to a ferromagnetic powder in which an ε-iron oxide type crystal structure is detected as the main phase by X-ray diffraction analysis. For example, when the highest intensity diffraction peak in the X-ray diffraction spectrum obtained by X-ray diffraction analysis is attributed to an ε-iron oxide type crystal structure, it is determined that the ε-iron oxide type crystal structure is detected as the main phase. Known methods for producing ε-iron oxide powder include a method of producing it from goethite and a reverse micelle method. All of the above production methods are publicly known. In addition, for a method for producing ε-iron oxide powder in which a part of Fe is replaced by a substitution atom such as Ga, Co, Ti, Al, or Rh, reference can be made to, for example, J. Jpn. Soc. Powder Metallurgy Vol. 61 Supplement, No. S1, pp. S280-S284, J. Mater. Chem. C, 2013, 1, pp.5200-5206, etc. However, the method for producing the ε-iron oxide powder that can be used as the ferromagnetic powder in the magnetic layer of the magnetic tape is not limited to the method given here.

[0063] The activation volume of the ε-iron oxide powder is preferably 300 to 1500 nm 3 The finely divided ε-iron oxide powder exhibiting an activation volume in the above range is suitable for producing a magnetic tape exhibiting excellent electromagnetic conversion characteristics. The activation volume of the ε-iron oxide powder is preferably 300 nm 3For example, 500 nm or more. 3 From the viewpoint of further improving the electromagnetic conversion characteristics, the activation volume of the ε-iron oxide powder can be 1400 nm or more. 3 More preferably, it is 1300 nm or less. 3 More preferably, it is 1200 nm or less. 3 More preferably, it is equal to or less than 1100 nm. 3 It is even more preferred that:

[0064] The anisotropy constant Ku can be used as an index of the reduction in thermal fluctuation, in other words, the improvement in thermal stability. The ε-iron oxide powder is preferably 3.0×10 4 J / m 3 More preferably, the Ku is 8.0×10 or more. 4 J / m 3 The Ku of the ε-iron oxide powder can be, for example, 3.0×10 5 J / m 3 However, since a higher Ku value means higher thermal stability and is preferable, the Ku value is not limited to the above-mentioned values.

[0065] From the viewpoint of increasing the reproduction output when reproducing data recorded on a magnetic tape, it is desirable that the mass magnetization σs of the ferromagnetic powder contained in the magnetic tape is high. In this regard, in one embodiment, the σs of the ε-iron oxide powder is 8 A m 2 / kg or more, and 12 A m 2 On the other hand, the σs of ε-iron oxide powder is 40 A m 2 / kg or less, and 35A·m 2 It is more preferable that the amount is not more than 1 / kg.

[0066] In the present invention and this specification, unless otherwise specified, the average particle size of various powders such as ferromagnetic powders is a value measured by the following method using a transmission electron microscope. The powder is photographed at a magnification of 100,000 times using a transmission electron microscope, and then printed on photographic paper at a total magnification of 500,000 times to obtain a photograph of the particles that make up the powder. From the obtained particle photograph, the target particle is selected, the particle's outline is traced with a digitizer, and the particle (primary particle) size is measured. Primary particles are independent particles that are not aggregated. The above measurements are carried out for 500 randomly selected particles. The arithmetic mean of the particle sizes of the 500 particles thus obtained is the average particle size of the powder. As the transmission electron microscope, for example, a Hitachi transmission electron microscope H-9000 type can be used. The particle size can be measured using known image analysis software, for example, Carl Zeiss image analysis software KS-400. The average particle size shown in the examples described below is a value measured using a Hitachi transmission electron microscope H-9000 type as the transmission electron microscope and Carl Zeiss image analysis software KS-400 as the image analysis software, unless otherwise specified. In the present invention and this specification, powder means a collection of multiple particles. For example, ferromagnetic powder means a collection of multiple ferromagnetic particles. In addition, the collection of multiple particles is not limited to a form in which the particles constituting the collection are in direct contact with each other, and also includes a form in which a binder, additive, etc., described later, are interposed between the particles. The term particle is sometimes used to refer to powder.

[0067] As a method for collecting sample powder from the magnetic tape for particle size measurement, for example, the method described in paragraph 0015 of JP 2011-048878 A can be used.

[0068] In the present invention and this specification, unless otherwise specified, the size of the particles constituting the powder (particle size) is determined by the shape of the particles observed in the particle photograph. (1) In the case of needle-shaped, spindle-shaped, columnar (where the height is greater than the maximum major axis of the base), etc., it is expressed by the length of the major axis that constitutes the particle, i.e., the major axis length. (2) In the case of a plate or columnar shape (where the thickness or height is smaller than the maximum long diameter of the plate or base), it shall be expressed by the maximum long diameter of the plate or base. (3) In the case of a particle having a spherical, polyhedral, or amorphous shape, and in which the major axis of the particle cannot be identified from its shape, the particle is expressed as the equivalent circle diameter, which is determined by the circle projection method.

[0069] The average acicular ratio of a powder refers to the arithmetic average of the short axis length of the particles, i.e., the short axis length, the (long axis length / short axis length) value of each particle, and the values ​​obtained for the 500 particles. Here, unless otherwise specified, the short axis length refers to the length of the short axis constituting the particle in the above definition of particle size (1), and to the thickness or height in the above definition of particle size (2), and in the above definition of particle size (3), since there is no distinction between the long axis and the short axis, (long axis length / short axis length) is considered to be 1 for the sake of convenience. Unless otherwise specified, when the particle shape is specific, for example, in the case of the above definition of particle size (1), the average particle size is the average major axis length, in the case of definition (2), the average particle size is the average plate diameter, and in the case of definition (3), the average particle size is the average diameter (also called the average particle diameter or average particle size).

[0070] 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 %. A high filling rate of the ferromagnetic powder in the magnetic layer is preferable from the viewpoint of improving recording density.

[0071] (Binding Agent) The magnetic tape may be a coated magnetic tape, and may contain a binder in the magnetic layer. The binder is one or more kinds of resin. As the binder, various resins that are usually used as binders for coated magnetic recording media may be used. For example, as the binder, a resin selected from polyurethane resin, polyester resin, polyamide resin, vinyl chloride resin, acrylic resin copolymerized with styrene, acrylonitrile, methyl methacrylate, etc., cellulose resin such as nitrocellulose, epoxy resin, phenoxy resin, polyvinyl acetal, polyvinyl butyral, etc. may be used alone or in combination. Among these, polyurethane resin, acrylic resin, cellulose resin, and vinyl chloride resin are preferred. These resins may be homopolymers or copolymers. These resins may also be used as binders in the non-magnetic layer and / or backcoat layer described below. For the above binders, reference can be made to paragraphs 0028 to 0031 of JP 2010-24113 A. The average molecular weight of the resin used as the binder can be, for example, 10,000 to 200,000 in weight average molecular weight. The weight average molecular weight in the present invention and this specification is a value obtained by converting a value measured under the following measurement conditions by gel permeation chromatography (GPC) into polystyrene equivalent. The weight average molecular weight of the binder shown in the examples described later is a value obtained by converting a value measured under the following measurement conditions into polystyrene equivalent. The binder can be used in an amount of, for example, 1.0 to 30.0 parts by mass with respect to 100.0 parts by mass of the ferromagnetic powder. GPC equipment: HLC-8120 (Tosoh Corporation) Column: TSK gel Multipore HXL-M (Tosoh Corporation, 7.8 mm ID (inner diameter) × 30.0 cm) Eluent: tetrahydrofuran (THF)

[0072] (hardening agent) A curing agent can be used together with the resin usable as a binder. In one embodiment, the curing agent can be a thermosetting compound, which is a compound in which a curing reaction (crosslinking reaction) proceeds by heating, and in another embodiment, the curing agent can be a photocuring compound in which a curing reaction (crosslinking reaction) proceeds by light irradiation. As the curing reaction proceeds in the magnetic layer forming process, at least a part of the curing agent can be contained in the magnetic layer in a state of reacting (crosslinking) with other components such as the binder. This point is also true for layers formed using a composition used to form other layers that contains a curing agent. A preferred curing agent is a thermosetting compound, and polyisocyanate is suitable. For details on polyisocyanate, refer to paragraphs 0124 to 0125 of JP 2011-216149 A. The curing agent can be used in an amount of, for example, 0 to 80.0 parts by mass relative to 100.0 parts by mass of the binder, and preferably 50.0 to 80.0 parts by mass from the viewpoint of improving the strength of the magnetic layer.

[0073] (Additives) The magnetic layer may contain one or more additives as necessary. An example of the additive is the curing agent described above. Examples of additives contained in the magnetic layer include non-magnetic powders (e.g., inorganic powders, carbon black, etc.), lubricants, dispersants, dispersion aids, antifungal agents, antistatic agents, antioxidants, etc. For example, reference can be made to paragraphs 0030 to 0033, 0035, and 0036 of JP2016-126817A for lubricants. The non-magnetic layer described below may contain a lubricant. Reference can be made to paragraphs 0030, 0031, 0034 to 0036 of JP2016-126817A for lubricants that may be contained in the non-magnetic layer. Reference can be made to paragraphs 0061 and 0071 of JP2012-133837A for dispersants. A dispersant may be added to the non-magnetic layer forming composition. For dispersants that can be added to the composition for forming the non-magnetic layer, reference can be made to paragraph 0061 of JP-A-2012-133837. Examples of non-magnetic powders that can be included in the magnetic layer include non-magnetic powders that can function as abrasives, and non-magnetic powders (e.g., non-magnetic colloidal particles) that can function as protrusion-forming agents that form protrusions that protrude appropriately on the surface of the magnetic layer. The average particle size of colloidal silica (silica colloidal particles) shown in the examples described below is a value determined by the method described in paragraph 0015 of JP-A-2011-048878 as a method for measuring average particle size. Additives can be appropriately selected from commercially available products according to the desired properties, or can be manufactured by known methods and used in any amount. Examples of additives that can be used to improve the dispersibility of an abrasive in a magnetic layer containing an abrasive include dispersants described in paragraphs 0012 to 0022 of JP-A-2013-131285.

[0074] The magnetic layer described above can be provided directly on the surface of the non-magnetic support, or indirectly via a non-magnetic layer.

[0075] <Nonmagnetic layer> Next, the non-magnetic layer will be described. The magnetic tape may have a magnetic layer directly on the surface of the non-magnetic support, or may have a magnetic layer on the surface of the non-magnetic support via a non-magnetic layer containing non-magnetic powder. The non-magnetic powder used in the non-magnetic layer may be an inorganic powder or an organic powder. Carbon black or the like may also be used. Examples of inorganic powder include powders of metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, metal sulfides, and the like. These non-magnetic powders are commercially available, and can also be produced by known methods. For details, refer to paragraphs 0146 to 0150 of JP-A-2011-216149. For carbon black usable in the non-magnetic layer, refer to paragraphs 0040 and 0041 of JP-A-2010-24113. The content (filling rate) of the non-magnetic powder in the non-magnetic layer is preferably in the range of 50 to 90% by mass, more preferably in the range of 60 to 90% by mass.

[0076] The non-magnetic layer may contain a binder and may also contain an additive. For other details of the binder, additive, etc. of the non-magnetic layer, known techniques related to non-magnetic layers can be applied. In addition, for example, for the type and content of the binder, the type and content of the additive, known techniques related to magnetic layers can also be applied.

[0077] In the present invention and this specification, the nonmagnetic layer also includes a substantially nonmagnetic layer that contains a small amount of ferromagnetic powder, for example as an impurity or intentionally, together with the nonmagnetic powder. Here, the substantially nonmagnetic layer refers to a layer having a residual magnetic flux density of 10 mT or less, a coercive force of 7.96 kA / m (100 Oe) or less, or a layer having a residual magnetic flux density of 10 mT or less and a coercive force of 7.96 kA / m (100 Oe) or less. It is preferable that the nonmagnetic layer has no residual magnetic flux density or coercive force.

[0078] (Backcoat layer) The magnetic tape may or may not have a backcoat layer containing a nonmagnetic powder on the surface side opposite to the surface side having the magnetic layer of the nonmagnetic support. The backcoat layer preferably contains either one or both of carbon black and inorganic powder. The backcoat layer may contain a binder and may also contain additives. For the binder and additives of the backcoat layer, known techniques related to the backcoat layer may be applied, and known techniques related to the formulation of the magnetic layer and / or nonmagnetic layer may also be applied. For example, the descriptions of paragraphs 0018 to 0020 of JP 2006-331625 A and US Pat. No. 7,029,774, column 4, line 65 to column 5, line 38, may be referred to for the backcoat layer.

[0079] <Various thicknesses> Regarding the thickness (total thickness) of the magnetic tape, with the enormous increase in the amount of information in recent years, there is a demand for the magnetic tape to have an increased recording capacity (high capacity). As a means for increasing the capacity, there is a need to reduce the thickness of the magnetic tape (hereinafter also referred to as "thinning") and increase the length of the magnetic tape contained in one magnetic tape cartridge. From this point of view, the thickness (total thickness) of the magnetic tape is preferably 5.6 μm or less, more preferably 5.5 μm or less, more preferably 5.4 μm or less, and even more preferably 5.3 μm or less. Also, from the viewpoint of ease of handling, the thickness of the magnetic tape is preferably 3.0 μm or more, and more preferably 3.5 μm or more. Regarding the thickness of the magnetic tape, the thinner the thickness, the higher the TC value tends to be.

[0080] The thickness (total thickness) of the magnetic tape can be measured by the following method. Ten tape samples (e.g., 5 to 10 cm long) are cut out from any part of the magnetic tape, and the tape samples are stacked and the thickness is measured. The measured thickness is divided by 10 to obtain the value (thickness per tape sample), which is the tape thickness. The thickness measurement can be performed using a known measuring device capable of measuring thickness to the order of 0.1 μm.

[0081] The thickness of the non-magnetic support is preferably 3.0 to 5.0 μm. The thickness of the magnetic layer can be optimized depending on the saturation magnetization amount of the magnetic head used, the head gap length, the band of the recording signal, etc., and is generally 0.01 μm to 0.15 μm, and from the viewpoint of high density recording, is preferably 0.02 μm to 0.12 μm, and more preferably 0.03 μm to 0.1 μm. At least one magnetic layer is sufficient, and the magnetic layer may be separated into two or more layers having different magnetic properties, and a known configuration related to a multilayer magnetic layer can be applied. When the magnetic layer is separated into two or more layers, the thickness of the magnetic layer is the total thickness of these layers. The thickness of the nonmagnetic layer is, for example, 0.1 to 1.5 μm, and preferably 0.1 to 1.0 μm. The thickness of the backcoat layer is preferably 0.9 μm or less, and more preferably 0.1 to 0.7 μm. Various thicknesses such as the thickness of the magnetic layer can be determined by the following method. A cross section of the magnetic tape in the thickness direction is exposed by an ion beam, and then the exposed cross section is observed by a scanning electron microscope. Various thicknesses can be obtained as the arithmetic average of thicknesses obtained at any two points in the cross section observation. Alternatively, various thicknesses can be obtained as design thicknesses calculated from manufacturing conditions, etc.

[0082] <Manufacturing process> (Preparation of compositions for forming each layer) The process of preparing the composition for forming the magnetic layer, non-magnetic layer or backcoat layer can usually include at least a kneading process, a dispersion process, and a mixing process provided before or after these processes as necessary. Each process may be divided into two or more stages. The components used in the preparation of the composition for forming each layer may be added at the beginning or during any process. As the solvent, one or more of various solvents usually used in the manufacture of coating-type magnetic recording media can be used. For the solvent, refer to paragraph 0153 of JP-A-2011-216149. Also, each component may be added in two or more steps in a divided manner. For example, the binder may be added in a divided manner in the kneading process, the dispersion process, and the mixing process for adjusting the viscosity after dispersion. In order to manufacture the magnetic tape, known manufacturing techniques can be used in various steps. In the kneading process, it is preferable to use a kneader with a strong kneading force, such as an open kneader, a continuous kneader, a pressure kneader, or an extruder. For details of the kneading treatment, reference can be made to JP-A-1-106338 and JP-A-1-79274. A known dispersing machine can be used. At any stage of preparing each layer-forming composition, filtration may be performed by a known method. Filtration can be performed, for example, by filter filtration. As the filter used for filtration, for example, a filter with a pore size of 0.01 to 3 μm (for example, a glass fiber filter, a polypropylene filter, etc.) can be used.

[0083] (coating process) The magnetic layer can be formed by directly applying the magnetic layer-forming composition onto the surface of the non-magnetic support, or by successively or simultaneously applying the magnetic layer-forming composition and the non-magnetic layer-forming composition in a multi-layer manner. The backcoat layer can be formed by applying the backcoat layer-forming composition onto the surface of the non-magnetic support opposite to the surface having the non-magnetic layer and / or magnetic layer (or the non-magnetic layer and / or magnetic layer will be provided later). For details of the coating for forming each layer, refer to paragraph 0066 of JP2010-231843A.

[0084] (Other processes) Known techniques can be applied to other various steps for manufacturing a magnetic tape. For various steps, see, for example, paragraphs 0067-0070 of JP-A-2010-231843. For example, the coating layer of the magnetic layer-forming composition can be subjected to an orientation treatment in an orientation zone while the coating layer is in a wet state. For the orientation treatment, various known techniques, including those described in paragraph 0052 of JP-A-2010-24113, can be applied. For example, the vertical orientation treatment can be performed by a known method such as a method using magnets with different poles facing each other. In the orientation zone, the drying speed of the coating layer can be controlled by the temperature and volume of the drying air and / or the transport speed in the orientation zone. In addition, the coating layer may be pre-dried before being transported to the orientation zone. A long magnetic tape roll can be obtained through various processes. The obtained magnetic tape roll is cut (slit) to the width of the magnetic tape to be wound into a magnetic tape cartridge by a known cutter. The width is determined according to standards and is usually 1 / 2 inch. 1 inch = 12.65 mm. A servo pattern is formed on the magnetic tape obtained by slitting, as will be described in detail later.

[0085] (Heat treatment) In one embodiment, the magnetic tape can be a magnetic tape manufactured through the following heat treatment: When the following heat treatment is performed, the TDSage value tends to become smaller.

[0086] The heat treatment can be carried out by winding the magnetic tape, which has been slit and cut to a width determined in accordance with a standard, around a core member and carrying out the heat treatment in the wound state.

[0087] In one embodiment, the above-mentioned heat treatment is performed with the magnetic tape wound around a core-shaped member for heat treatment (hereinafter referred to as the "heat treatment core"), and the magnetic tape after heat treatment is wound onto a reel of a magnetic tape cartridge, thereby producing a magnetic tape cartridge in which the magnetic tape is wound around a reel. The heat treatment core may be made of metal, resin, paper, or the like. The material of the heat treatment core is preferably a material with high rigidity from the viewpoint of suppressing the occurrence of winding failures such as sporking. From this viewpoint, the heat treatment core is preferably made of metal or resin. In addition, as an index of rigidity, the bending modulus of the material of the heat treatment core is preferably 0.2 GPa or more, more preferably 0.3 GPa or more. On the other hand, since high rigidity materials are generally expensive, using a heat treatment core of a material having a rigidity exceeding the rigidity that can suppress the occurrence of winding failures leads to an increase in cost. In consideration of the above, the bending modulus of the material of the heat treatment core is preferably 250 GPa or less. The bending modulus is a value measured according to ISO (International Organization for Standardization) 178, and the bending modulus of various materials is publicly known. In addition, the heat treatment core may be a solid or hollow core-shaped member. In the case of a hollow shape, the wall thickness is preferably 2 mm or more from the viewpoint of maintaining rigidity. In addition, the heat treatment core may or may not have a flange. It is preferable to prepare a magnetic tape having a length equal to or greater than the length (hereinafter referred to as the "final product length") to be finally accommodated in a magnetic tape cartridge as the magnetic tape to be wound around the core for heat treatment, and to perform heat treatment by placing the magnetic tape wound around the core for heat treatment in a heat treatment environment. The length of the magnetic tape to be wound around the core for heat treatment is equal to or greater than the final product length, and from the viewpoint of ease of winding around the core for heat treatment, it is preferable that the length is "final product length + α". From the viewpoint of ease of winding, this α is preferably 5 m or more. The tension during winding around the core for heat treatment is preferably 0.1 N (Newton) or more. In addition, from the viewpoint of suppressing the occurrence of excessive deformation, the tension during winding around the core for heat treatment is preferably 1.5 N or less, more preferably 1.0 N or less. The outer diameter of the core for heat treatment is preferably 20 mm or more, more preferably 40 mm or more, from the viewpoint of ease of winding and suppression of coiling (longitudinal curl). The outer diameter of the heat treatment core is preferably 100 mm or less, more preferably 90 mm or less. The width of the heat treatment core may be equal to or greater than the width of the magnetic tape wound around the core. After the heat treatment, when removing the magnetic tape from the heat treatment core, it is preferable to remove the magnetic tape from the heat treatment core after the magnetic tape and the heat treatment core have been sufficiently cooled in order to prevent unintended deformation of the tape during the removal operation. The removed magnetic tape is preferably once wound around another core (called a "temporary winding core"), and then the magnetic tape is preferably wound from the temporary winding core onto a reel of a magnetic tape cartridge (generally with an outer diameter of about 40 to 50 mm). This allows the magnetic tape to be wound around the reel of a magnetic tape cartridge while maintaining the relationship between the inside and outside of the magnetic tape with respect to the heat treatment core during the heat treatment. For details of the temporary winding core and the tension when winding the magnetic tape around this core, the above description of the heat treatment core can be referred to. In a form in which the above-mentioned heat treatment is performed on a magnetic tape having a length of "final product length + α", the length of "+ α" can be cut off at any stage. For example, in one form, the magnetic tape of the final product length can be wound from a temporary winding core onto a reel of a magnetic tape cartridge, and the remaining length of "+ α" can be cut off.From the viewpoint of reducing the portion that is cut off and discarded, the above α is preferably 20 m or less.

[0088] A specific embodiment of the heat treatment performed in the state where the material is wound around the core member as described above will be described below. The atmospheric temperature at which the heat treatment is performed (hereinafter referred to as "heat treatment temperature") is preferably 40° C. or higher, and more preferably 50° C. or higher. On the other hand, from the viewpoint of suppressing excessive deformation, the heat treatment temperature is preferably 75° C. or lower, more preferably 70° C. or lower, and even more preferably 65° C. or lower. The weight absolute humidity of the atmosphere in which the heat treatment is carried out is preferably 0.1 g / kg dry air or more, more preferably 1 g / kg dry air or more. An atmosphere with a weight absolute humidity in the above range is preferable because it can be prepared without using a special device for reducing moisture. On the other hand, the weight absolute humidity is preferably 70 g / kg dry air or less, more preferably 66 g / kg dry air or less, from the viewpoint of suppressing the occurrence of condensation and the deterioration of workability. The heat treatment time is preferably 0.3 hours or more, more preferably 0.5 hours or more. Moreover, the heat treatment time is preferably 48 hours or less from the viewpoint of production efficiency.

[0089] (Formation of servo pattern) “Formation of a servo pattern” can also be called “recording of a servo signal.” The formation of a servo pattern will be described below.

[0090] The servo pattern is usually formed along the longitudinal direction of the magnetic tape. Control methods that use servo signals (servo control) include timing-based servo (TBS), amplitude servo, and frequency servo.

[0091] As shown in ECMA (European Computer Manufacturers Association)-319 (June 2001), magnetic tapes (generally called "LTO tapes") conforming to the LTO (Linear Tape-Open) standard employ a timing-based servo system. In this timing-based servo system, a servo pattern is formed by a pair of non-parallel magnetic stripes (also called "servo stripes") arranged continuously in the longitudinal direction of the magnetic tape. In this invention and this specification, the "timing-based servo pattern" refers to a servo pattern that enables head tracking in a servo system of the timing-based servo system. As described above, the servo pattern is formed by a pair of non-parallel magnetic stripes in order to inform the servo signal reading element passing over the servo pattern of its passing position. Specifically, the pair of magnetic stripes is formed so that the interval between them changes continuously along the width direction of the magnetic tape, and the servo signal reading element can know the relative position between the servo pattern and the servo signal reading element by reading the interval. This relative position information enables tracking of the data track. For this reason, a plurality of servo tracks are usually set on the servo pattern along the width direction of the magnetic tape.

[0092] A servo band is made up of a continuous servo pattern in the longitudinal direction of the magnetic tape. Usually, 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. The data band is made up of multiple data tracks, and each data track corresponds to one servo track.

[0093] Also, in one embodiment, as shown in JP 2004-318983 A, information indicating the number of the servo band (also called "servo band ID (identification)" or "UDIM (Unique Data Band Identification Method) information") is embedded in each servo band. This servo band ID is recorded by shifting a specific one of a plurality of pairs of servo stripes in the servo band so that its position is displaced relatively in the longitudinal direction of the magnetic tape. Specifically, the way in which a specific one of a plurality of pairs of servo stripes is shifted is changed for each servo band. As a result, the recorded servo band ID is unique for each servo band, so that the servo band can be uniquely identified simply by reading one servo band with a servo signal reading element.

[0094] As a method for uniquely identifying servo bands, there is also a method using the staggered method as shown in ECMA-319 (June 2001). In this staggered method, a group of pairs of non-parallel magnetic stripes (servo stripes) arranged continuously in the longitudinal direction of the magnetic tape are recorded so that they are shifted in the longitudinal direction of the magnetic tape for each servo band. The combination of the shift between adjacent servo bands is unique across the entire magnetic tape, so when the servo pattern is read by two servo signal reading elements, it is possible to uniquely identify the servo bands.

[0095] Also, as specified in ECMA-319 (June 2001), information indicating the longitudinal position of the magnetic tape (also called "LPOS (Longitudinal Position) information") is usually embedded in each servo band. Like UDIM information, this LPOS information is also recorded by shifting the positions of a pair of servo stripes in the longitudinal direction of the magnetic tape. However, unlike UDIM information, the same signal is recorded in each servo band with this LPOS information.

[0096] It is also possible to embed information other than the above UDIM information and LPOS information in the servo bands. In this case, the embedded information may be different for each servo band, such as UDIM information, or may be common to all servo bands, such as LPOS information. Also, methods other than those described above can be used to embed information in the servo bands. For example, a predetermined code may be recorded by thinning out a predetermined pair from a group of pairs of servo stripes.

[0097] The head for forming a servo pattern is called a servo write head. The servo write head usually has a pair of gaps corresponding to the pair of magnetic stripes, the number of which is equal to the number of servo bands. Usually, a core and a coil are connected to each pair of gaps, and a magnetic field generated in the core can generate a leakage magnetic field in the pair of gaps by supplying a current pulse to the coil. When forming a servo pattern, a magnetic pattern corresponding to the pair of gaps can be transferred to the magnetic tape by inputting a current pulse while running the magnetic tape on the servo write head, thereby forming the servo pattern. The width of each gap can be appropriately set according to the density of the servo pattern to be formed. The width of each gap can be set, for example, to 1 μm or less, 1 to 10 μm, or 10 μm or more.

[0098] Before forming a servo pattern on the magnetic tape, the magnetic tape is usually subjected to a demagnetization (erase) process. This erase process can be performed by applying a uniform magnetic field to the magnetic tape using a direct current magnet or an alternating current magnet. There are two types of erase processes: DC (Direct Current) erase and AC (Alternating Current) erase. AC erase is performed by gradually lowering the strength of the magnetic field applied to the magnetic tape while reversing the direction of the magnetic field. On the other hand, DC erase is performed by applying a unidirectional magnetic field to the magnetic tape. There are two more methods of DC erase. The first method is horizontal DC erase, which applies a unidirectional magnetic field along the longitudinal direction of the magnetic tape. The second method is vertical DC erase, which applies a unidirectional magnetic field along the thickness direction of the magnetic tape. The erase process may be performed on the entire magnetic tape, or may be performed for each servo band of the magnetic tape.

[0099] The direction of the magnetic field of the formed servo pattern is determined according to the direction of erasure. For example, when the magnetic tape is subjected to horizontal DC erasure, the servo pattern is formed so that the direction of the magnetic field is opposite to the direction of erasure. This makes it possible to increase the output of the servo signal obtained by reading the servo pattern. As shown in JP2012-53940A, when the magnetic pattern is transferred to the magnetic tape that has been vertically DC erased using the above gap, the servo signal obtained by reading the formed servo pattern has a unipolar pulse shape. On the other hand, when the magnetic pattern is transferred to the magnetic tape that has been horizontally DC erased using the above gap, the servo signal obtained by reading the formed servo pattern has a bipolar pulse shape.

[0100] [Magnetic tape cartridge] One aspect of the present invention relates to a magnetic tape cartridge including the above-mentioned magnetic tape.

[0101] The details of the magnetic tape contained in the tape cartridge are as described above.

[0102] In a magnetic tape cartridge, the magnetic tape is generally accommodated inside the cartridge body in a state where it is wound around a reel. The reel is provided rotatably inside the cartridge body. As the magnetic tape cartridge, a single-reel type magnetic tape cartridge having one reel inside the cartridge body and a twin-reel type magnetic tape cartridge having two reels inside the cartridge body are widely used. When a single-reel type 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 wound around the reel on the magnetic tape device side. A magnetic head is disposed on the magnetic tape transport path from the magnetic tape cartridge to the take-up reel. The magnetic tape is fed and wound between the reel (supply reel) on the magnetic tape cartridge side and the reel (take-up reel) on the magnetic tape device side. During this time, the magnetic head comes into contact with and slides on the surface of the magnetic layer of the magnetic tape, thereby recording and / or reproducing data. 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.

[0103] In one embodiment, the magnetic tape cartridge may include a cartridge memory. The cartridge memory may be, for example, a non-volatile memory, in which tension adjustment information has already been recorded, or tension adjustment information will be recorded. The tension adjustment information is information for adjusting the tension applied in the longitudinal direction of the magnetic tape. For more information on the cartridge memory, please refer to the description below.

[0104] The above magnetic tape and magnetic tape cartridge can be suitably used in a magnetic tape device (in other words, a magnetic recording and reproducing system) that controls the width direction of the magnetic tape by adjusting the tension applied to the magnetic tape in the longitudinal direction.

[0105] [Magnetic tape device] One aspect of the present invention relates to a magnetic tape device including a magnetic tape cartridge. In the magnetic tape device, data can be recorded on the magnetic tape and / or data recorded on the magnetic tape can be reproduced by bringing a magnetic head into contact with the surface of the magnetic layer of the magnetic tape and sliding the magnetic head. The magnetic tape device can detachably include the magnetic tape cartridge according to one aspect of the present invention.

[0106] 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. In the present invention and this specification, the term "magnetic tape device" refers to a device capable of recording data on a magnetic tape and / or reproducing data recorded on the magnetic tape. Such a device is generally called a drive. The magnetic head included in the magnetic tape device can be a recording head capable of recording data on the magnetic tape, and can also be a reproducing head capable of reproducing data recorded on the magnetic tape. In one embodiment, the magnetic tape device can include both a recording head and a reproducing head as separate magnetic heads. In another embodiment, the magnetic head included in the magnetic tape device can have a configuration in which both a recording element and a reproducing element are provided in one magnetic head. As the reproducing head, a magnetic head (MR head) that includes a magnetoresistive (MR) element as a reproducing element capable of reading information recorded on a magnetic tape with good sensitivity is preferable. As the MR head, various known MR heads (for example, a GMR (Giant Magnetoresistive) head, a TMR (Tunnel Magnetoresistive) head, etc.) can be used. A servo pattern reading element may be included in the magnetic head that records and / or reproduces data. Alternatively, a magnetic head (servo head) equipped with a servo pattern reading element may be included in the magnetic tape device as a head separate from the magnetic head that records and / or reproduces data. For example, a magnetic head that records and / or reproduces recorded data (hereinafter also referred to as a "recording and reproducing head") may include two servo signal reading elements, and each of the two servo signal reading elements can simultaneously read two adjacent servo bands sandwiching a data band. One or more data elements may be disposed between the two servo signal reading elements. An element for recording data (a recording element) and an element for reproducing data (a reproducing element) are collectively referred to as a "data element".

[0107] By using a reproducing element with a narrow reproducing element width as the reproducing element to reproduce data, data recorded at a high density can be reproduced with high sensitivity. From this viewpoint, the reproducing element width of the reproducing element is preferably 0.8 μm or less. The reproducing element width of the reproducing element can be, for example, 0.3 μm or more. However, from the above viewpoint, it is also preferable that the reproducing element width is less than this value. On the other hand, the narrower the reproducing element width, the more likely it is that phenomena such as poor reproduction caused by off-track will occur. In order to suppress the occurrence of such phenomena, a magnetic tape device that controls the dimension of the magnetic tape in the width direction by adjusting the tension applied in the longitudinal direction of the magnetic tape is preferable. Here, the "reading element width" refers to the physical dimension of the width of the reading element. Such physical dimension can be measured using an optical microscope, a scanning electron microscope, or the like.

[0108] When recording data and / or reproducing recorded data, tracking can be performed using servo signals first. That is, by making the servo signal reading element follow a specific servo track, the data element can be controlled to pass over the target data track. The data track is moved by changing the servo track read by the servo signal reading element in the tape width direction. The recording / reproducing head can also record and / or reproduce data on other data bands by using the UDIM information described above to move the servo signal reading element to a specific servo band and start tracking on that servo band.

[0109] FIG. 1 shows an example of the arrangement of data bands and servo bands. In FIG. 1, a plurality of servo bands 1 are arranged on the magnetic layer of the magnetic tape MT, sandwiched between guide bands 3. A plurality of regions 2 sandwiched between two servo bands are data bands. A servo pattern is a magnetized region, and is formed by magnetizing a specific region of the magnetic layer with a servo write head. The region magnetized by the servo write head (the position where the servo pattern is formed) is determined by a standard. For example, in an LTO Ultrium format tape, which is an industry standard, a plurality of servo patterns inclined with respect to the tape width direction are formed on the servo band during the manufacturing of the magnetic tape, as shown in FIG. 2. More specifically, in FIG. 2, a servo frame SF on the servo band 1 is composed of a servo subframe 1 (SSF1) and a servo subframe 2 (SSF2). The servo subframe 1 is composed of an A burst (symbol A in FIG. 2) and a B burst (symbol B in FIG. 2). The A burst is composed of servo patterns A1 to A5, and the B burst is composed of servo patterns B1 to B5. On the other hand, the servo subframe 2 is composed of a C burst (symbol C in FIG. 2) and a D burst (symbol D in FIG. 2). The C burst is composed of servo patterns C1 to C4, and the D burst is composed of servo patterns D1 to D4. Such 18 servo patterns are arranged in a subframe arranged in a 5, 5, 4, 4 arrangement in a set of 5 and 4, and are used to identify a servo frame. For the sake of explanation, one servo frame is shown in FIG. 2. However, in reality, a plurality of servo frames are arranged in the running direction in each servo band on the magnetic layer of a magnetic tape where head tracking of the timing-based servo method is performed. In FIG. 2, the arrow indicates the running direction. For example, an LTO Ultrium format tape usually has 5,000 or more servo frames per meter of tape length in each servo band on the magnetic layer.

[0110] The magnetic tape device preferably has a tension adjustment mechanism for controlling the width dimension of the magnetic tape by adjusting the tension applied to the magnetic tape in the longitudinal direction. An example of such a magnetic tape device will be described below with reference to Fig. 3. However, the present invention is not limited to the example shown in Fig. 3.

[0111] <Magnetic tape device configuration> A magnetic tape device 10 shown in FIG. 3 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 capable of detecting and adjusting 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 capable of reading from and writing to a cartridge memory 131 in the magnetic tape cartridge 13 . From the magnetic tape cartridge 13 attached to the magnetic tape device 10, the end or leader pin of the magnetic tape MT is pulled out by an automatic loading mechanism or manually, and the magnetic tape MT passes over the recording / playback head via guide rollers 15A and 15B with the magnetic layer surface in a direction facing the recording / playback head surface of the recording / playback head unit 12, and the magnetic tape MT is taken up onto the take-up reel 16. The rotation and torque of spindle motors 17A and 17B are controlled by signals from control device 11, and magnetic tape MT runs at any speed and tension. A servo pattern formed in advance on the magnetic tape can be used to control the tape speed. A tension detection mechanism may be provided between magnetic tape cartridge 13 and take-up reel 16 to detect the tension. The tension may be adjusted using guide rollers 15A and 15B in addition to the control by spindle motors 17A and 17B. The cartridge memory read / write device 14 is configured to be able to read and write information from and to the cartridge memory 131 in response to commands from the control device 11. As a communication method between the cartridge memory read / write device 14 and the cartridge memory 131, for example, the ISO (International Organization for Standardization) 14443 method can be adopted.

[0112] The control device 11 includes, for example, a control unit, a storage unit, a communication unit, and the like.

[0113] The recording and reproducing head unit 12 is composed of, for example, a recording and reproducing head, a servo tracking actuator that adjusts the position of the recording and reproducing head in the track width direction, a recording and reproducing amplifier 19, a connector cable for connecting to the control device 11, etc. The recording and reproducing head is composed of, for example, a recording element that records data on the magnetic tape, a reproducing element that reproduces the data on the magnetic tape, and a servo signal reading element that reads the servo signal recorded on the magnetic tape. One magnetic head is equipped with, for example, one or more of each of the recording element, reproducing element, and servo signal reading element. Alternatively, each element may be provided separately in a plurality of magnetic heads according to the running direction of the magnetic tape.

[0114] The recording / reproducing head unit 12 is configured to be capable of recording data onto the magnetic tape MT in response to a command from the control device 11. Also, the recording / reproducing head unit 12 is configured to be capable of reproducing the data recorded onto the magnetic tape MT in response to a command from the control device 11.

[0115] The control device 11 has a mechanism for determining the running position of the magnetic tape MT from the servo signal read from the servo band while the magnetic tape MT is running, and for controlling the servo tracking actuator so that the recording element and / or the reproducing element are positioned at the target running position (track position). This control of the track position is performed, for example, by feedback control. The control device 11 has a mechanism for determining the servo band interval from the servo signals read from two adjacent servo bands while the magnetic tape MT is running. The control device 11 also has a mechanism for adjusting the tension applied in the longitudinal direction of the magnetic tape by controlling the torque of the spindle motor 17A and the spindle motor 17B and / or the guide rollers 15A and 15B so that the servo band interval becomes a target value. This tension adjustment is performed, for example, by feedback control. The control device 11 can also store information on the determined servo band interval in a storage unit inside the control device 11, a cartridge memory 131, an external connected device, or the like.

[0116] In the magnetic tape device, the tension applied in the longitudinal direction of the magnetic tape during recording and / or playback can be variably adjusted. In the range in which this tension adjustment is performed (hereinafter also referred to as the "tension adjustment range"), the minimum tension can be, for example, 0.10 N or more, and from the viewpoint of improving running stability, it is preferable that it is 0.20 N or more. In the tension adjustment range, the maximum tension can be, for example, 1.30 N or less, and from the viewpoint of improving running stability, it is preferable that it is 1.20 N or less. It is presumed that the stability of servo tracking is improved by setting the tension adjustment range to the range of 0.2 N to 1.2 N, which is thought to lead to improved running stability. The tension value related to the tension adjustment range is the tension value used by the control device of the magnetic tape device to control the mechanism for adjusting the tension as the tension to be applied in the longitudinal direction of the magnetic tape during tension adjustment. In the magnetic tape device, the tension actually applied in the longitudinal direction of the magnetic tape during tension adjustment can be detected, for example, by providing a tension detection mechanism between the magnetic tape cartridge 13 and the take-up reel 16 in FIG. 3, as described above. Furthermore, for example, the minimum tension can be controlled by a control device of the magnetic tape device so that it does not fall below a value specified or recommended by a standard, etc., and / or the maximum tension can be controlled so that it does not exceed a value specified or recommended by a standard, etc. EXAMPLES

[0117] An embodiment of the present invention will be described below based on an example. However, the present invention is not limited to the embodiment shown in the example. The indications of "parts" and "%" below mean "parts by mass" and "% by mass" unless otherwise specified. "eq" is an equivalent, and is a unit that cannot be converted to SI units. In addition, the following various steps and operations were carried out in an environment with a temperature of 20 to 25° C. and a relative humidity of 40 to 60%, unless otherwise specified.

[0118] In Table 1, "PEN" indicates a polyethylene naphthalate support and "PET" indicates a polyethylene terephthalate support. The water content and Young's modulus in Table 1 are values ​​measured by the method described above.

[0119] [Example 1] (1) Preparation of alumina dispersion Alpha conversion rate approximately 65%, BET (Brunauer-Emmett-Teller) specific surface area 20m 2 100.0 parts of alumina powder (HIT-80 manufactured by Sumitomo Chemical Co., Ltd.) with a molecular weight of 1.0 g / g was mixed with 3.0 parts of 2,3-dihydroxynaphthalene (manufactured by Tokyo Chemical Industry Co., Ltd.) and SO 3 31.3 parts of a 32% solution (solvent is a mixed solvent of methyl ethyl ketone and toluene) of polyester polyurethane resin having a Na group (UR-4800 (polar group amount: 80 meq / kg) manufactured by Toyobo Co., Ltd.) was mixed with 570.0 parts of a mixed solution of methyl ethyl ketone and cyclohexanone at a 1:1 (mass ratio) as a solvent, and dispersed for 5 hours in the presence of zirconia beads using a paint shaker. After dispersion, the dispersion liquid and the beads were separated using a mesh to obtain an alumina dispersion.

[0120] (2) Magnetic layer forming composition formulation (Magnetic liquid) Ferromagnetic powder 100.0 parts Hexagonal barium ferrite powder with an average particle size (average plate diameter) of 21 nm ("BaFe" in Table 1) SO3 Sodium-containing polyurethane resin 14.0 parts Weight average molecular weight: 70,000, SO 3 Sodium group: 0.2 meq / g Cyclohexanone 150.0 parts Methyl ethyl ketone 150.0 parts (abrasive liquid) 6.0 parts of the alumina dispersion prepared in (1) above (Silica sol (protrusion forming liquid)) Colloidal silica (average particle size 120 nm) 2.0 parts Methyl ethyl ketone 1.4 parts (Other Ingredients) Stearic acid 2.0 parts Stearic acid amide 0.2 parts Butyl stearate 2.0 parts Polyisocyanate (Tosoh Corporation, Coronate (registered trademark) L) 2.5 parts (Finishing solvent) Cyclohexanone 200.0 parts Methyl ethyl ketone 200.0 parts

[0121] (3) Formulation of composition for forming nonmagnetic layer Non-magnetic inorganic powder: α-iron oxide 100.0 parts Average particle size (average major axis length): 0.15μm Average acicular ratio: 7 BET specific surface area: 52m 2 / g Carbon black 20.0 parts Average particle size: 20nm SO 3 Sodium-containing polyurethane resin 18.0 parts Weight average molecular weight: 70,000, SO 3 Sodium group: 0.2 meq / g Stearic acid 2.0 parts Stearic acid amide 0.2 parts Butyl stearate 2.0 parts Cyclohexanone 300.0 parts Methyl ethyl ketone 300.0 parts

[0122] (4) Formulation of composition for forming backcoat layer Carbon black 100.0 parts DBP (Dibutyl phthalate) oil absorption 74cm 3 / 100g Nitrocellulose 27.0 parts Polyester polyurethane resin containing sulfonic acid groups and / or their salts 62.0 copies Polyester resin 4.0 parts Alumina powder (BET specific surface area: 17m 2 / g) 0.6 parts Methyl ethyl ketone 600.0 parts Toluene 600.0 parts Polyisocyanate (Tosoh Corporation, Coronate (registered trademark) L) 15.0 parts

[0123] (5) Preparation of compositions for forming each layer The magnetic layer forming composition was prepared by the following method. The magnetic liquid was prepared by dispersing each component for 24 hours (bead dispersion) using a batch-type vertical sand mill. Zirconia beads with a bead diameter of 0.5 mm were used as the dispersion beads. The prepared magnetic liquid, the abrasive liquid, and other components (silica sol, other components, and finishing additive solvent) were mixed using the sand mill and dispersed with beads for 5 minutes, and then treated with a batch-type ultrasonic device (20 kHz, 300 W) for 0.5 minutes (ultrasonic dispersion). After that, filtration was performed using a filter with a pore size of 0.5 μm to prepare the magnetic layer forming composition. The composition for forming the nonmagnetic layer was prepared by the following method. The above components, except for the lubricants (stearic acid, stearic acid amide, and butyl stearate), were kneaded and diluted using an open kneader, and then dispersed using a horizontal bead mill disperser. The lubricants (stearic acid, stearic acid amide, and butyl stearate) were then added, and the mixture was stirred and mixed using a dissolver stirrer to prepare the composition for forming the nonmagnetic layer. The composition for forming a backcoat layer was prepared by the following method. The above components except for the polyisocyanate were introduced into a dissolver mixer, stirred at a peripheral speed of 10 m / sec for 30 minutes, and then dispersed using a horizontal bead mill disperser. Then, the polyisocyanate was added, and the mixture was stirred and mixed using the dissolver mixer to prepare the composition for forming a backcoat layer.

[0124] (6) Methods for manufacturing magnetic tapes and magnetic tape cartridges On the surface of the biaxially stretched support of the type and thickness shown in Table 1, the nonmagnetic layer-forming composition prepared in (5) above was applied and dried to a thickness of 1.0 μm after drying to form a nonmagnetic layer. Next, the magnetic layer-forming composition prepared in (5) above was applied on the nonmagnetic layer to a thickness of 0.1 μm after drying to form a coating layer. Thereafter, while the coating layer of the magnetic layer-forming composition was still in a wet state, a magnetic field with a magnetic field strength of 0.3 T was applied in a direction perpendicular to the surface of the coating layer to perform a vertical orientation treatment, and then the coating layer was dried to form a magnetic layer. Then, the backcoat layer-forming composition prepared in (5) above was applied and dried on the surface of the support opposite to the surface on which the nonmagnetic layer and magnetic layer were formed to a thickness of 0.5 μm after drying to form a backcoat layer. Thereafter, a surface smoothing treatment (calendering) was performed using a calender roll consisting only of a metal roll at a speed of 100 m / min, a linear pressure of 300 kg / cm, and a calender temperature (surface temperature of the calender roll) of 90°C. Thereafter, the long magnetic tape was heat-treated by storing it in a heat treatment furnace at an atmospheric temperature of 70°C (heat treatment time: 36 hours). After the heat treatment, the magnetic tape was slit into 1 / 2 inch width to obtain a magnetic tape. A servo signal was recorded on the magnetic layer of the obtained magnetic tape by a commercially available servo writer to obtain a magnetic tape having a data band, a servo band, and a guide band in an arrangement according to the LTO (Linear Tape-Open) Ultrium format, and having a servo pattern (timing-based servo pattern) on the servo band with an arrangement and shape according to the LTO Ultrium format. The servo pattern thus formed is a servo pattern according to the descriptions of JIS (Japanese Industrial Standards) X6175:2006 and Standard ECMA-319 (June 2001). The total number of servo bands is 5, and the total number of data bands is 4. The magnetic tape (length 970 m) after the servo pattern was formed was wound around a core for heat treatment, and heat treatment was performed while the tape was wound around the core. A solid core-shaped member (outer diameter: 50 mm) made of resin with a flexural modulus of 0.8 GPa was used as the core for heat treatment, and the tension during winding was 0.6 N. The heat treatment was performed for 5 hours at the heat treatment temperature shown in Table 1. The weight absolute humidity of the atmosphere in which the heat treatment was performed was 10 g / kg dry air. After the above heat treatment, the magnetic tape and the core for heat treatment were sufficiently cooled, and then the magnetic tape was removed from the core for heat treatment and wound onto the core for temporary winding, and then the magnetic tape for the final product length (960 m) was wound from the core for temporary winding onto a reel (reel outer diameter: 44 mm) of a magnetic tape cartridge (LTO Ultrium 7 data cartridge), and the remaining 10 m was cut off, and a leader tape was joined to the end of the cut-off side using a commercially available splicing tape in accordance with item 9 of Standard ECMA (European Computer Manufacturers Association)-319 (June 2001) Section 3. The core for temporary winding was a solid core member made of the same material and having the same outer diameter as the core for heat treatment, and the tension during winding was 0.6 N. As a result of the above, a single-reel type magnetic tape cartridge of Example 1 was produced, in which a magnetic tape of 960 m in length was wound around a reel.

[0125] [Examples 2 to 10, Comparative Examples 1 and 2] A magnetic tape cartridge was produced in the same manner as in Example 1, except that the items in Table 1 were changed as shown in Table 1. In the examples and comparative examples in Table 1 where the "Heat treatment temperature" column is marked with "-", no heat treatment was performed while the magnetic tape was wound around the heat treatment core, and the magnetic tape having a final product length of 960 m was housed in a magnetic tape cartridge.

[0126] [Example 11] A magnetic tape cartridge was produced in the same manner as in Example 1, except that a hexagonal strontium ferrite powder ("SrFe1" in Table 1) prepared as follows was used as the ferromagnetic powder. SrCO 3 1707g, H 3 BO 3 687g, Fe 2 O 3 1120g, Al(OH) 3 45g BaCO 3 24g, CaCO 3 13g, and Nd 2O 3 The above was weighed out in an amount of 235 g and mixed in a mixer to obtain a raw material mixture. The obtained raw material mixture was melted in a platinum crucible at a melting temperature of 1390°C, and the melt was poured into a rod shape at about 6 g / sec by heating the tapping hole at the bottom of the platinum crucible while stirring the melt. The tapped liquid was rolled and quenched with a water-cooled twin roller to produce an amorphous body. 280 g of the produced amorphous body was placed in an electric furnace, heated to 635°C (crystallization temperature) at a heating rate of 3.5°C / min, and held at that temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles. Next, the crystallized material obtained above containing hexagonal strontium ferrite particles was coarsely crushed in a mortar, and 1000 g of zirconia beads with a particle size of 1 mm and 800 mL of 1% aqueous acetic acid solution were added to a glass bottle and dispersed for 3 hours using a paint shaker. The resulting dispersion was then separated from the beads and placed in a stainless steel beaker. The dispersion was left to stand at a liquid temperature of 100°C for 3 hours to dissolve the glass components, and then precipitated in a centrifuge and washed by repeated decantation, and dried for 6 hours in a heating furnace at a furnace temperature of 110°C to obtain hexagonal strontium ferrite powder. The average particle size of the hexagonal strontium ferrite powder obtained above is 18 nm, and the activation volume is 902 nm. 3 , the anisotropy constant Ku is 2.2×10 5 J / m 3 , mass magnetization σs is 49A m 2 / kg. A 12 mg sample powder was taken from the hexagonal strontium ferrite powder obtained above, and this sample powder was partially dissolved under the dissolution conditions exemplified above. The elemental analysis of the filtrate obtained was performed using an ICP analyzer to determine the surface layer content of neodymium atoms. Separately, 12 mg of sample powder was taken from the hexagonal strontium ferrite powder obtained above, and this sample powder was completely dissolved under the dissolution conditions exemplified above. The elemental analysis of the filtrate obtained was performed using an ICP analyzer to determine the bulk content of neodymium atoms. The neodymium atom content (bulk content) relative to 100 atomic % of iron atoms in the hexagonal strontium ferrite powder obtained above was 2.9 atomic %. The surface layer content of neodymium atoms was 8.0 atomic %. The ratio of the surface layer content to the bulk content, "surface layer content / bulk content," was 2.8, confirming that neodymium atoms were unevenly distributed in the surface layers of the particles.

[0127] It was confirmed that the powder obtained above exhibited a hexagonal ferrite crystal structure by scanning with CuKα radiation at a voltage of 45 kV and an intensity of 40 mA and measuring the X-ray diffraction pattern under the following conditions (X-ray diffraction analysis). The powder obtained above exhibited a magnetoplumbite-type (M-type) hexagonal ferrite crystal structure. The crystal phase detected by the X-ray diffraction analysis was a single phase of magnetoplumbite type. PANalytical X'Pert Pro diffractometer, PIXcel detector Soller slits for incident and diffracted beams: 0.017 radians Dispersion slit fixed angle: 1 / 4 degree Mask: 10mm Anti-scatter slit: 1 / 4 degree Measurement mode: Continuous Measurement time per step: 3 seconds Measurement speed: 0.017 degrees per second Measurement step: 0.05 degrees

[0128] [Example 12] A magnetic tape cartridge was produced in the same manner as in Example 1, except that a hexagonal strontium ferrite powder ("SrFe2" in Table 1) prepared as follows was used as the ferromagnetic powder. SrCO 3 1725g, H 3 BO 3 666g, Fe 2 O 3 1332g, Al(OH) 3 52g, CaCO 3 34g, BaCO 3 The above was weighed out in an amount of 141 g and mixed in a mixer to obtain a raw material mixture. The obtained raw material mixture was melted in a platinum crucible at a melting temperature of 1380°C, and the melt was poured into a rod shape at about 6 g / sec by heating the tapping hole at the bottom of the platinum crucible while stirring the melt. The tapped liquid was quenched and rolled with a water-cooled twin roll to produce an amorphous body. 280 g of the obtained amorphous body was placed in an electric furnace, heated to 645° C. (crystallization temperature), and held at that temperature for 5 hours to precipitate (crystallize) hexagonal strontium ferrite particles. Next, the crystallized material obtained above containing hexagonal strontium ferrite particles was coarsely crushed in a mortar, and 1000 g of zirconia beads with a particle size of 1 mm and 800 mL of 1% aqueous acetic acid solution were added to a glass bottle and dispersed for 3 hours using a paint shaker. The resulting dispersion was then separated from the beads and placed in a stainless steel beaker. The dispersion was left to stand at a liquid temperature of 100°C for 3 hours to dissolve the glass components, and then precipitated in a centrifuge and washed by repeated decantation, and dried for 6 hours in a heating furnace at a furnace temperature of 110°C to obtain hexagonal strontium ferrite powder. The average particle size of the obtained hexagonal strontium ferrite powder was 19 nm, and the activation volume was 1102 nm. 3 , the anisotropy constant Ku is 2.0×10 5 J / m 3 , mass magnetization σs is 50A m 2 / kg.

[0129] [Example 13] A magnetic tape cartridge was produced in the same manner as in Example 1, except that ε-iron oxide powder prepared as follows (in Table 1, "ε-iron oxide") was used as the ferromagnetic powder. 8.3g of iron (III) nitrate nonahydrate, 1.3g of gallium (III) nitrate octahydrate, 190mg of cobalt (II) nitrate hexahydrate, 150mg of titanium (IV) sulfate, and 1.5g of polyvinylpyrrolidone (PVP) were dissolved in 90g of pure water, and 4.0g of ammonia solution with a concentration of 25% was added under the condition of an atmospheric temperature of 25°C while stirring with a magnetic stirrer in the air, and the mixture was stirred for 2 hours at an atmospheric temperature of 25°C. A citric acid solution obtained by dissolving 1g of citric acid in 9g of pure water was added to the obtained solution, and the mixture was stirred for 1 hour. The powder precipitated after stirring was collected by centrifugation, washed with pure water, and dried in a heating furnace at an internal temperature of 80°C. 800g of pure water was added to the dried powder, and the powder was dispersed in water again to obtain a dispersion. The obtained dispersion was heated to 50°C, and 40g of 25% ammonia aqueous solution was added dropwise while stirring. After stirring for 1 hour while maintaining the temperature at 50°C, 14mL of tetraethoxysilane (TEOS) was added dropwise and stirred for 24 hours. 50g of ammonium sulfate was added to the obtained reaction solution, and the precipitated powder was collected by centrifugation, washed with pure water, and dried for 24 hours in a heating furnace with an internal temperature of 80°C to obtain a precursor of ferromagnetic powder. The obtained precursor of the ferromagnetic powder was placed in a heating furnace at an internal temperature of 1000° C. in an air atmosphere and subjected to a heat treatment for 4 hours. The heat-treated ferromagnetic powder precursor was placed in a 4 mol / L aqueous solution of sodium hydroxide (NaOH), and the liquid temperature was maintained at 70°C while stirring for 24 hours, thereby removing the impurity silicate compound from the heat-treated ferromagnetic powder precursor. Thereafter, the silicic acid compound was removed by centrifugation, and the ferromagnetic powder was collected and washed with pure water to obtain a ferromagnetic powder. The composition of the obtained ferromagnetic powder was confirmed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The results showed that the powder was composed of Ga, Co, and Ti substituted ε-iron oxide (ε-Ga 0.28 Co 0.05 Ti 0.05 Fe 1.62 O 3In addition, X-ray diffraction analysis was performed under the same conditions as those described above for the hexagonal strontium ferrite powder SrFe1, and it was confirmed from the peaks in the X-ray diffraction pattern that the obtained ferromagnetic powder had a single-phase ε-phase crystal structure (ε-iron oxide type crystal structure) that did not contain 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.

[0130] The activation volume and anisotropy constant Ku of the above hexagonal strontium ferrite powder and ε-iron oxide powder were determined for each ferromagnetic powder by the method described above using a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd.). The mass magnetization σs is a value measured using a vibrating sample magnetometer (manufactured by Toei Industry Co., Ltd.) at a magnetic field strength of 1194 kA / m (15 kOe).

[0131] [Magnetic tape evaluation] (1) TDSage The magnetic tape cartridge containing the magnetic tape to be measured was placed in an environment with an ambient temperature of 23° C. and a relative humidity of 50% for five days in order to acclimate it to the measurement environment. Thereafter, under this measurement environment, the magnetic tape was run in the magnetic tape device shown in Figure 3 with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. During this run, the distance between two adjacent servo bands sandwiching a data band was measured at 1 m intervals over the entire length of the magnetic tape. Measurements were performed for all servo band distances. The servo band distances measured in this way were designated as the "servo band distance before storage" at each measurement position. The distance between two adjacent servo bands sandwiching a data band was determined as follows. To determine the distance between two adjacent servo bands with a data band in between, the dimensions of the servo pattern are required. The standards for the dimensions of the servo pattern differ depending on the generation of LTO. First, we use a magnetic force microscope or similar to measure the average distance AC between the four corresponding stripes of the A burst and the C burst, and the azimuth angle α of the servo pattern. Next, the servo patterns formed on the magnetic tape are read sequentially along the tape longitudinal direction using a reel tester and a servo head equipped with two servo signal reading elements (hereinafter, one is called the upper side and the other is called the lower side) fixed at an interval in a direction perpendicular to the longitudinal direction of the magnetic tape. The average time between five stripes corresponding to A burst and B burst over the length of one LPOS word is defined as a. The average time between four stripes corresponding to A burst and C burst over a length of 1 m is defined as b. In this case, the value defined as AC×(1 / 2-a / b) / (2×tan(α)) represents the read position PES in the width direction based on the servo signal obtained by the servo signal reading element. The servo patterns are read simultaneously by two servo signal reading elements on the upper and lower sides. The value of PES obtained by the upper servo signal reading element is defined as PES1, and the value of PES obtained by the lower servo signal reading element is defined as PES2. The interval between two adjacent servo bands sandwiching a data band can be obtained as "PES2-PES1". This is because the upper and lower servo pattern reading elements are fixed to the servo head and the distance between them does not change. Thereafter, the magnetic tape cartridge was stored in an environment having an atmospheric temperature of 60° C. and a relative humidity of 20% for 24 hours. After this storage, the magnetic tape cartridge was placed in a measurement environment with an ambient temperature of 23°C and a relative humidity of 50% for 5 days, and then, under the same measurement environment, the magnetic tape was run in the magnetic tape device shown in Figure 3 with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. During this run, the servo band interval was measured in the same manner as described above. The servo band interval measured in this manner was taken as the "servo band interval after storage" at each measurement position. For all servo band intervals, the difference between the servo band intervals measured at 1m intervals before and after storage was calculated. In this way, multiple difference values ​​were calculated. The maximum absolute value of the calculated differences was determined as the "TDSage" of the magnetic tape being measured.

[0132] (2) TDSenv Measurements were performed in five environments (temperature 16°C and relative humidity 20%, temperature 16°C and relative humidity 80%, temperature 26°C and relative humidity 80%, temperature 32°C and relative humidity 20%, and temperature 32°C and relative humidity 55%) using the following methods. For each measurement environment, a magnetic tape cartridge containing a magnetic tape to be measured was placed in the measurement environment for five days to allow the magnetic tape to become accustomed to the measurement environment. Then, under the measurement environment, the magnetic tape was run in the magnetic tape device shown in Fig. 3 with a tension of 0.7 N applied in the longitudinal direction of the magnetic tape. The servo band intervals were measured for the above run at 1 m intervals in a 100 m region around the reel circumference, at data band 0 (zero), by the method described in (1) above. As described above, the arithmetic mean of the measured servo band intervals was taken as the servo band interval in the measurement environment. After determining the servo band spacing in each of the five environments as described above, the maximum and minimum values ​​obtained were used to calculate "(maximum value - minimum value) x 1 / 2", which was used as the "TDSenv" of the magnetic tape being measured.

[0133] (3)TC Measurements were performed in five environments (temperature 16°C and relative humidity 20%, temperature 16°C and relative humidity 80%, temperature 26°C and relative humidity 80%, temperature 32°C and relative humidity 20%, and temperature 32°C and relative humidity 55%) using the following methods. For each measurement environment, a magnetic tape cartridge containing a magnetic tape to be measured was placed in the measurement environment for five days to allow the magnetic tape to become accustomed to the measurement environment. Thereafter, under the measurement environment, the following measurements were carried out in the magnetic tape device shown in FIG. The magnetic tape was run with a tension of 0.2 N applied in the longitudinal direction of the magnetic tape. During this run, the servo band intervals were measured at 1 m intervals in the data band 0 (zero) in a 100 m area around the reel. The arithmetic mean of the measured servo band intervals was defined as "G 0.2N " G 0.2N After measuring the servo band interval, the tension applied to the magnetic tape in the longitudinal direction is increased to 0.4N, and the servo band interval is measured in the same manner as above while the tension of 0.4N is applied. The arithmetic mean of the measured servo band interval is calculated as "G 0.4N " G 0.4N After measuring the tension in the longitudinal direction of the magnetic tape, increase the tension to 0.6N, and measure the servo band interval in the same manner as above while applying a tension of 0.6N. The arithmetic mean of the measured servo band intervals is called "G 0.6N " G 0.6N After measuring the servo band interval, increase the tension applied to the magnetic tape in the longitudinal direction to 0.8N, and measure the servo band interval in the same manner as above while applying a tension of 0.8N. The measured servo band interval is calculated as "G 0.8N " G 0.8N After measuring the servo band interval, increase the tension applied to the magnetic tape in the longitudinal direction to 1.0 N, and measure the servo band interval in the same manner as above while applying a tension of 1.0 N. The arithmetic average of the measured servo band intervals is called "G 1.0N " G 1.0N After measuring the servo band interval, the tension applied to the magnetic tape in the longitudinal direction is increased to 1.2N, and the servo band interval is measured in the same manner as above while the tension of 1.2N is applied. The arithmetic mean of the measured servo band interval is calculated as "G 1.2N " The G calculated by the above method 0.2N , G 0.4N , G 0.6N , G 0.8N , G 1.0N and G 1.2NThe absolute value of the slope A obtained by the least squares method using the servo band spacing (i.e., the above arithmetic average obtained by each measurement) obtained with tension as X and each tension as Y of the linear function Y = AX + B (A is the slope and B is the intercept) was determined as "TDStens", which is the ratio of the change in servo band spacing to the change in tension in the measurement environment. The above measurements were performed in the five environments. The minimum TDStens value found in each of the five environments was adopted as the "TDStens" value for calculating the TC of the magnetic tape being measured, and this TDStens value (unit: μm / N) was multiplied by 0.5N, i.e., the value calculated as "TDStens x 0.5" was used as the "TC" of the magnetic tape being measured.

[0134] From the various values ​​obtained above, the left side of Equation 1 (i.e., "TDSage+TDSenv-TC") was calculated. The calculated values ​​are shown in Table 1.

[0135] (4) Tape thickness After the above evaluation, the magnetic tape cartridge was placed in an environment with a temperature of 20 to 25°C and a relative humidity of 40 to 60% for 5 days or more to allow it to acclimate to the environment. Then, still in the same environment, 10 tape samples (5 cm long) were cut out from any part of the magnetic tape taken out of the magnetic tape cartridge, and these tape samples were stacked and the thickness was measured. The thickness was measured using a digital thickness meter with a Millimar 1240 compact amplifier and a Millimar 1301 inductive probe manufactured by MARH. The measured thickness was divided by 10 to obtain the value (thickness per tape sample), which was taken as the tape thickness. The tape thickness for each magnetic tape was as shown in Table 1.

[0136] [Evaluation of recording and playback performance] The recording and playback performance was evaluated using a magnetic tape device with the configuration shown in Figure 3. The recording and playback head mounted on the recording and playback head unit has 32 or more channels of playback elements (playback element width: 0.8 μm) and recording elements, with servo signal reading elements on both sides. Each magnetic tape cartridge of the Example and Comparative Example was placed for 5 days or more in the environment in which the servo band interval obtained in the measurement for obtaining TDSenv was the maximum among the above 5 environments. After being acclimatized to the environment in this way, data was recorded in the same environment as described below. A magnetic tape cartridge is set in a magnetic tape device and the magnetic tape is loaded. Next, pseudo-random data with a specific data pattern is recorded onto the magnetic tape by the recording / playback head unit while performing servo tracking. At this time, a tension of 0.7 N is applied along the length of the tape. When recording data, recording is performed three or more times back and forth so that the difference in the (PES1+PES2) / 2 value between adjacent tracks is 1.16 μm. At the same time as recording the data, the servo band spacing value over the entire length of the tape is measured every 1 m along the length and recorded in the cartridge memory. The magnetic tape cartridge on which data had been recorded as described above was placed in a storage environment at an atmospheric temperature of 60° C. and a relative humidity of 20% for 24 hours. Then, each of the magnetic tape cartridges of the examples and comparative examples was placed for 5 days or more in the environment in which the servo band interval obtained in the measurement for obtaining TDSenv was the smallest among the above 5 environments. After being acclimatized to the environment in this way, data was reproduced in the same environment as described below. A magnetic tape cartridge is set in a magnetic tape device, and the magnetic tape is loaded. Next, the data recorded on the magnetic tape is reproduced by the recording / reproducing head unit while performing servo tracking. At this time, the value of the servo band interval is measured simultaneously with the reproduction, and the tension applied in the longitudinal direction of the tape is adjusted so that the absolute value of the difference from the servo band interval at the time of recording at the same longitudinal position approaches 0 based on the information recorded in the cartridge memory. During reproduction, the measurement of the servo band interval and the tension adjustment based on the measurement are performed continuously in real time. During reproduction using each of the magnetic tape cartridges of the examples and comparative examples, the maximum and minimum tensions among the tension values ​​used by the control device 11 for the above tension adjustment were the values ​​shown in Table 1.

[0137] The number of channels in the above playback was 32. During playback, if data from all 32 channels was read correctly, the recording and playback performance was rated as "3." If data from channels 31 to 28 was read correctly, the recording and playback performance was rated as "2." In all other cases, the recording and playback performance was rated as "1."

[0138] [Evaluation of driving stability] The running stability was evaluated using a magnetic tape device with the configuration shown in Figure 3. The recording / playback head mounted on the recording / playback head unit has 32 or more channels of playback elements (playback element width: 0.8 μm) and recording elements, with servo signal reading elements on both sides. Each of the magnetic tape cartridges of the Examples and Comparative Examples was placed in a measurement environment of an ambient temperature of 23° C. and a relative humidity of 50% for 5 days or more. After being acclimatized to the measurement environment in this manner, the running stability was evaluated in the same environment as described below. A magnetic tape cartridge is set in a magnetic tape device, and the magnetic tape is loaded. Next, the magnetic tape is repeatedly run over the entire length while performing servo tracking. The tape running speed is in the range of 4 to 7 m / s. The tension applied to the magnetic tape in the longitudinal direction is variable within the range of the minimum tension and the maximum tension listed in Table 1. During running, the previously described "PES1" and "PES2" are continuously measured for each servo frame, and if these values ​​exceed ±0.3 μm with respect to the servo tracking position, it is determined that off-track has occurred. Running is performed continuously for 24 hours, and if off-track occurrence is measured once or more in each running pass (full length one way) in servo frames of 1% or more of the entire length of the magnetic tape, the running stability is evaluated as "B", and if no off-track occurrence is measured, the running stability is evaluated as "A".

[0139] The above results are shown in Table 1. [Table 1]

[0140] From the results shown in Table 1, it can be confirmed that the magnetic tape of the embodiment is a magnetic tape that can be suitably used in a magnetic tape device that controls the width dimension of the magnetic tape by adjusting the tension applied in the longitudinal direction of the magnetic tape. Furthermore, it can also be seen from the results shown in Table 1 that from the viewpoint of running stability, the tension adjustment range is preferably between 0.2N and 1.2N. [Industrial Applicability]

[0141] One aspect of the present invention is useful in various data storage technical fields.

Claims

1. A non-magnetic support and a magnetic layer containing ferromagnetic powder, the magnetic layer has a plurality of servo bands; The following formula 1: (Formula 1) TDSage+TDSenv-TC≦0.30μm Fulfilling In formula 1, TDSage is the maximum absolute value of the difference between the servo band intervals obtained before and after 24 hours of storage in an environment with a temperature of 60° C. and a relative humidity of 20%, and is expressed in μm. The TDSage is 0.00 μm or more and 3.00 μm or less, TDSenv runs in the following five environments: Temperature 16℃, relative humidity 20%, Temperature 16℃, relative humidity 80%, Temperature 26°C, relative humidity 80%, Temperature 32°C, relative humidity 20%, Temperature 32°C, relative humidity 55%, The value is calculated by multiplying the difference between the maximum and minimum values ​​of the servo band intervals obtained by each of the above steps by 1 / 2, and is expressed in μm. TC is a value calculated by multiplying TDStens by 0.5N, TDSTens applies multiple different tensions to the magnetic tape in the longitudinal direction under the following five conditions: Temperature 16℃, relative humidity 20%, Temperature 16℃, relative humidity 80%, Temperature 26°C, relative humidity 80%, Temperature 32°C, relative humidity 20%, Temperature 32°C, relative humidity 55%, The ratio of the change in the servo band interval to the change in tension is calculated from the servo band intervals obtained in the above items and is expressed in units of μm / N.

2. The following formula 1-1: (Formula 1-1) TDSage+TDSenv-TC≦0.05μm 2. The magnetic tape according to claim 1,

3. 3. The magnetic tape according to claim 1, wherein the TDSage is greater than 0.00 μm and not greater than 2.50 μm.

4. 3. The magnetic tape according to claim 1, wherein the TDSage is 0.05 μm or more and 2.00 μm or less.

5. 3. The magnetic tape according to claim 1, wherein the TDSage is 0.05 μm or more and 1.50 μm or less.

6. 6. The magnetic tape according to claim 1, wherein the tape thickness is 5.6 μm or less.

7. 7. The magnetic tape according to claim 1, wherein the tape thickness is 5.3 μm or less.

8. 8. The magnetic tape according to claim 1, further comprising a non-magnetic layer containing non-magnetic powder between the non-magnetic support and the magnetic layer.

9. 9. The magnetic tape according to claim 1, further comprising a backcoat layer containing a nonmagnetic powder on the surface of the nonmagnetic support opposite to the surface having the magnetic layer.

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

11. 11. The magnetic tape of claim 10, wherein the aromatic polyester support is a polyethylene terephthalate support.

12. 11. The magnetic tape of claim 10, wherein the aromatic polyester support is a polyethylene naphthalate support.

13. A magnetic tape cartridge comprising the magnetic tape according to any one of claims 1 to 12.

14. A magnetic tape device comprising the magnetic tape cartridge according to claim 13.

15. 15. The magnetic tape device according to claim 14, wherein tension applied to the magnetic tape in the longitudinal direction while the magnetic tape is running within the magnetic tape device is variably adjusted.

16. 16. The magnetic tape device according to claim 15, wherein the tension is adjusted in a range of 0.2N to 1.2N.

17. 17. The magnetic tape device according to claim 14, further comprising a magnetic head having a read element with a read element width of 0.8 μm or less.

Images