magnetic recording cartridge

Abstract

The objective of the present invention is to provide a magnetic recording cartridge that, even when stored under a high-temperature environment, enables width correction in the longitudinal direction of the magnetic recording medium by adjusting the travelling tensile force of the tape system or changing the winding direction of the tape system.　This magnetic recording cartridge includes a reel, and a magnetic recording medium having a base layer, with the loss modulus of the base layer at 65 °C being 0.40 GPa or less. When the magnetic recording medium is taken up on the reel and the change in width over the total span of the magnetic recording medium is measured after being stored for 360 hours at 65 °C, the sign of the change in width Δout on the outer side of the roll differs from the sign of the change in width Δin on the inner side of the roll. The change in width is 0 ppm at a location of either of two sections that flank the center line of the total span of the magnetic recording medium, among four sections obtained by dividing the total span of the magnetic recording medium into four equal sections.

Description

[Technical Field]

[0001] The present technology relates to magnetic recording cartridges. [Background technology]

[0002] In recent years, demand for archiving has increased, and high-capacity data storage devices have been incorporated into cloud systems. To improve data recording density, magnetic tape (magnetic recording media) used for data storage has become increasingly narrow in track width and distance between adjacent tracks. As track width and distance between tracks become narrower, the maximum allowable dimensional change of the tape itself due to environmental factors such as temperature and humidity changes becomes increasingly smaller.

[0003] Several techniques have been proposed to reduce the amount of dimensional change. For example, the magnetic tape medium disclosed in Patent Document 1 has a Young's modulus of 850 kg / mm2, where X is the Young's modulus of the non-magnetic support in the width direction and Y is the Young's modulus of the back layer in the width direction. 2 or more or 850 kg / mm 2 If X×Y is less than 6×10 5 The magnetic layer is characterized in that, when the Young's modulus in the width direction of the layer including the magnetic layer is Z, Y / Z is 6.0 or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-332510 Summary of the Invention [Problem to be solved by the invention]

[0005] The main purpose of this technology is to provide a magnetic recording cartridge that allows the longitudinal width of the magnetic recording medium to be adjusted by adjusting the running tension of the tape system or changing the winding direction, even when stored in a high-temperature environment. [Means for solving the problem]

[0006] This technology is a magnetic recording medium having a base layer; a reel; The base layer has a loss modulus of 0.40 GPa or less at 65°C, the magnetic recording medium is wound on the reel, and When the amount of change in width was measured over the entire length of the magnetic recording medium after storage at 65°C for 360 hours, The sign of the width change amount Δout on the outer side of the winding is different from the sign of the width change amount Δin on the inner side of the winding, and the width change amount is 0 ppm at any of two portions sandwiching a center line of the entire length of the magnetic recording medium when the entire length of the magnetic recording medium is divided into four equal parts; A magnetic recording cartridge is provided. The width change amount Δin may be a positive value, and the width change amount Δout may be a negative value. When the entire length of the magnetic recording medium in the longitudinal direction is taken as 100%, the width change Δ of the magnetic recording medium after storage at 65° C. for 360 hours can be 0 ppm at a position 25% to 75% from the outer end of the winding. (The width change amount Δin)−(The width change amount Δout) may be 800 ppm or less. The base layer may have a storage modulus at 65° C. of 8.0 GPa or less. The base layer may be formed from PET (polyethylene terephthalate), PEN (polyethylene naphthalate), or PEEK (polyether ether ketone). The average thickness t of the magnetic recording medium T can be 5.6 μm or less. The average thickness t of the magnetic recording medium T can be 5.4 μm or less. The base layer has an average thickness t B can be 5.0 μm or less. The base layer has an average thickness t B can be 4.6 μm or less. According to one embodiment of the present technology, the magnetic recording medium may include a magnetic layer, and the magnetic layer may include magnetic powder. According to another embodiment of the present technology, the magnetic recording medium may include a magnetic layer, and the magnetic layer may be a sputtered layer. This technology is The magnetic recording cartridge is wound around a reel and is housed in the magnetic recording cartridge, When the width change amount was measured over the entire length after storing the film wound on the reel at 65°C for 360 hours, The sign of the width change amount Δout on the outer side of the winding is different from the sign of the width change amount Δin on the inner side of the winding, and The width change amount is 0 ppm at any of two portions on either side of the center line of the entire length when the entire length is divided into four equal parts, and A magnetic recording medium is provided that has a base layer with a loss modulus at 65°C of 0.40 GPa or less. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an exploded perspective view showing a magnetic recording cartridge according to an embodiment of the present technology; [Figure 2] 1 is a schematic diagram of a magnetic recording medium according to an embodiment of the present technology, viewed from the side; [Figure 3] FIG. 2 is a schematic diagram of the magnetic recording medium as viewed from above (the magnetic layer side). [Figure 4] FIG. 2 is an enlarged view showing recording tracks in a data band of the magnetic recording medium. [Figure 5] FIG. 2 is an enlarged view showing a servo pattern written in a servo band of the magnetic recording medium. [Figure 6] FIG. 1 is a diagram illustrating a recording and playback device. [Figure 7]FIG. 2 is a schematic diagram of a drive head in the recording / reproducing device. [Figure 8] FIG. 2 is a diagram showing a state when the recording / reproducing device is recording / reproducing a data signal. [Figure 9] 1 is a front view showing a servo pattern recording device according to an embodiment of the present technology; [Figure 10] FIG. 2 is a partially enlarged view showing a part of the servo pattern recording device. [Figure 11] 1A is a diagram showing the data structure of an LPOS word embedded in a servo pattern, and FIG. 1B is a diagram explaining a manufacturer word. [Figure 12] 1A is a schematic plan view showing an example of the arrangement of the servo pattern 6, and FIG. 1B is a diagram showing the reproduced waveform thereof. [Figure 13] 3A and 3B are schematic diagrams showing configuration examples of a first servo pattern and a second servo pattern. [Figure 14] 3A and 3B are diagrams showing reproduced waveforms of the first servo pattern and the second servo pattern, respectively. [Figure 15] FIG. 2 is a perspective view schematically showing the configuration of a servo write head in the servo pattern recording device. [Figure 16] FIG. 2 is a block diagram showing a configuration of a drive unit in the servo pattern recording device. [Figure 17] 3A and 3B are diagrams each schematically showing a recording signal waveform of a first servo subframe in a first pulse signal and a second pulse signal. [Figure 18] FIG. 10 is an exploded perspective view showing a modified example of the magnetic recording cartridge according to the embodiment of the present technology. [Figure 19] 10A and 10B are diagrams illustrating a method for measuring a servo band pitch using the recording and reproducing device. [Figure 20] FIG. 10 is a diagram illustrating a method for measuring a servo trace line. [Figure 21] FIG. 2 is a cross-sectional view showing the configuration of a magnetic particle. [Figure 22] FIG. 10 is a cross-sectional view showing the configuration of a magnetic particle in a modified example. [Figure 23]FIG. 10 is a cross-sectional view showing the configuration of a magnetic recording medium according to a second embodiment. [Figure 24] FIG. 1 is a schematic diagram showing the configuration of a sputtering apparatus. [Figure 25] FIG. 10 is a cross-sectional view showing the configuration of another example of the magnetic recording medium according to the second embodiment. [Figure 26] 1 is a graph showing an example of an SFD curve. [Figure 27] FIG. 1 is a diagram showing how the entire length of a magnetic tape is divided into four equal parts into four regions. [Figure 28] FIG. 1 is a graph showing the change in width in the longitudinal direction of a magnetic tape after storage at 65° C. for 360 hours, relating to Example 1. [Figure 29] FIG. 10 is a graph showing the change in width in the longitudinal direction of the magnetic tape after storage at 65° C. for 360 hours, relating to Example 2. [Figure 30] FIG. 10 is a graph showing the change in width in the longitudinal direction of the magnetic tape after storage at 65° C. for 360 hours, relating to Example 3. [Figure 31] FIG. 10 is a graph showing the change in width in the longitudinal direction of the magnetic tape after storage at 65° C. for 360 hours, relating to Example 4. [Figure 32] FIG. 10 is a graph showing the change in width in the longitudinal direction of a magnetic tape after storage at 65° C. for 360 hours in Comparative Example 1. [Figure 33] FIG. 10 is a graph showing the change in width in the longitudinal direction of a magnetic tape after storage at 65° C. for 360 hours, for Comparative Example 2. [Figure 34] FIG. 10 is a graph showing the change in width in the longitudinal direction of a magnetic tape after storage at 65° C. for 360 hours, for Comparative Example 3. [Figure 35] FIG. 10 is a graph showing the change in width in the longitudinal direction of the magnetic tape after storage at 65° C. for 360 hours in Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments for carrying out the present technology will be described below. Note that the embodiments described below are representative embodiments of the present technology, and the scope of the present technology is not limited to these embodiments.

[0009] This technology will be described in the following order. 1. Description of this technology 2. First embodiment (example of magnetic recording cartridge including coating-type magnetic recording medium) (1) Structure of magnetic recording cartridge (2) Recording and playback device (3) Configuration of Modified Magnetic Recording Cartridge (4) Description of each layer of magnetic recording media (5) Physical properties and structure of magnetic recording media (6) Manufacturing method of magnetic recording medium (7) Effects (8) Variations 3. Second embodiment (example of magnetic recording cartridge including vacuum thin film magnetic recording medium) (1) Structure of magnetic recording cartridge (2) Description of each layer of magnetic recording media (3) Physical properties and structure of magnetic recording media (4) Configuration of the sputtering equipment (5) Manufacturing method of magnetic recording medium (6) Effects (7) Variations (8) Other examples of magnetic recording media 4. Working Example

[0010] 1. Description of this technology

[0011] There is a demand for a further increase in the recording capacity per magnetic recording cartridge. For example, in order to increase the recording capacity, it is conceivable to make the magnetic recording medium (e.g., magnetic tape) included in the magnetic recording cartridge thinner (reducing the overall thickness) and thereby increase the tape length per magnetic recording cartridge. However, as magnetic recording media become thinner, dimensional changes in the track width direction can occur more easily. Dimensional changes in the width direction can cause undesirable phenomena in magnetic recording, such as off-track phenomena. The off-track phenomenon refers to a situation in which the target track is not present at the track position where the magnetic head should read, or the magnetic head reads the wrong track position. The magnetic tape contained in magnetic recording cartridges has a narrower usable temperature range than HDDs, and has been used in temperatures up to 45°C. By enabling magnetic recording cartridges to be used in high-temperature environments of 60°C or higher, similar to HDDs, it will become easier to manage the temperature environment when incorporating magnetic recording cartridges into data storage systems such as cloud systems, and it is expected that the range of use of tape storage systems will be greatly expanded. However, when the magnetic tape wound on the reel of a magnetic recording cartridge is stored in a high temperature environment of 60°C or higher, the part on the inside of the reel that is subjected to high winding stress expands in the width direction of the magnetic tape, while the part on the outside of the reel that is pulled in the longitudinal direction by the tension on the magnetic recording tape narrows in the width direction due to the creep phenomenon, and the difference in width between the inside and outside of the reel tends to increase.

[0012] Conventionally, in order to suppress dimensional changes in magnetic recording media, for example, a method has been used in which a layer for suppressing dimensional changes in the magnetic recording media is added. However, the addition of such layers may increase the thickness of the magnetic recording tape, without increasing the tape length per cartridge product.

[0013] The present inventors have investigated a magnetic recording medium suitable for use in a recording and reproducing device that can maintain a constant or nearly constant width of a long magnetic recording medium by adjusting the tension in the longitudinal direction of the magnetic recording medium. The recording and reproducing device detects, for example, the dimension or change in dimension of the magnetic recording medium in the width direction and adjusts the tension in the longitudinal direction based on the detection result. However, after storage in a high-temperature environment of 60°C or higher, the difference between the width on the inside and outside of the roll becomes large, and therefore, it is difficult to maintain a constant or nearly constant width of the magnetic recording medium even if the longitudinal tension is adjusted using the recording / reproducing device.

[0014] In light of the above, the present inventors have studied magnetic recording cartridges with a high recording capacity per cartridge. As a result, the present inventors have discovered that a magnetic recording cartridge having a specific configuration has a high recording capacity and that the longitudinal width can be adjusted by adjusting the running tension of the tape system or changing the winding direction, even when stored in a high-temperature environment of 60°C or higher. Note that, for example, in a one-reel cartridge, the winding direction can be changed by winding the magnetic tape onto the reel on the drive side, and in a two-reel cartridge, the winding direction can be changed by rewinding the magnetic tape onto the reel opposite to the way it was stored. For example, if the magnetic tape has been stored wound on the left reel, the direction can be changed by rewinding it onto the right reel. That is, the present technology provides a magnetic recording cartridge including a magnetic recording medium having a base layer and a reel, wherein the base layer has a loss modulus of 0.40 GPa or less at 65°C. The magnetic recording medium is accommodated in a wound state on the reel, and when the width change of the magnetic recording medium is measured over its entire length after storage at 65°C for 360 hours, the sign of the width change Δout on the outside of the reel is different from the sign of the width change Δin on the inside of the reel, and the width change is 0 ppm at either of the two portions on either side of the center line of the entire length of the magnetic recording medium when the entire length of the magnetic recording medium is divided into four equal parts. The method for measuring the width change of the magnetic recording medium will be described below in 2.(5).

[0015] The base layer of the magnetic recording medium included in the magnetic recording cartridge of the present technology may have a loss modulus at 65° C. of 0.40 GPa or less, preferably 0.35 GPa or less, more preferably 0.30 GPa or less, even more preferably 0.25 GPa or less, and even more preferably 0.20 GPa or less. When the loss modulus at 65° C. of the base layer of the magnetic recording medium is within the above numerical range, the width in the longitudinal direction can be adjusted by adjusting the running tension of the tape system or changing the winding direction, even when stored in a high-temperature environment of 60° C. or higher. The lower limit of the loss modulus of the base layer at 65°C is not particularly limited, but may be, for example, preferably 0.01 GPa or more, more preferably 0.02 GPa or more, and even more preferably 0.03 GPa or more. The method for measuring the loss modulus of the base layer at 65°C will be described in 2.(5) below.

[0016] The storage modulus of the base layer of the magnetic recording medium included in the magnetic recording cartridge of the present technology may be preferably 8.0 GPa or less, more preferably 7.0 GPa or less, and even more preferably 6.0 GPa or less at 65° C. When the storage modulus of the base layer of the magnetic recording medium at 65° C. is within the above numerical range, it is possible to provide a magnetic recording cartridge that allows the longitudinal width of the magnetic recording medium to be adjusted by adjusting the running tension or changing the winding direction of the tape system even after storage in a high-temperature environment. The lower limit of the storage modulus of the base layer at 65°C is not particularly limited, but may be, for example, preferably 0.01 GPa or more, more preferably 0.02 GPa or more, and even more preferably 0.03 GPa or more. The method for measuring the storage modulus of the base layer at 65°C will be described in 2.(5) below.

[0017] In the magnetic recording cartridge of the present technology, the magnetic recording medium is wound on a reel, and when the width change amount is measured over the entire length of the magnetic recording medium after storage at 65° C. for 360 hours, the sign of the width change amount Δout on the outside of the reel is different from the sign of the width change amount Δin on the inside of the reel. The width change amount Δ can be expressed by the following formula. Width change Δ = (width change after storage at 65°C and 360°C - width change in initial state) / (width change in initial state) If the width change amount Δ is a negative value, it indicates that the width after storage is narrower than the width in the initial state, and if the width change amount Δ is a positive value, it indicates that the width after storage is wider than the width in the initial state.

[0018] Magnetic recording cartridges are classified into those having one reel and those having two reels. In both types of magnetic recording cartridges, a magnetic recording medium (magnetic tape) is wound onto a reel and housed within the magnetic cartridge. As the magnetic recording media are wound onto the reels during magnetic cartridge manufacturing, the magnetic recording media are stacked to form a stack of magnetic recording media. In this specification, the "inner side of the reel" refers to the innermost layer of the stack of magnetic recording media when the magnetic recording media are wound onto a single reel to form a stack on that reel before the first data is recorded onto the magnetic cartridge, and the "outer side of the reel" refers to the outermost layer of the stack of magnetic recording media. More specifically, the inside of the winding refers to the area starting from the end (hereinafter also referred to as the "inner end" (EOT)) of the two ends of the magnetic recording medium that is attached to the reel inside the magnetic recording cartridge (the reel onto which the magnetic recording medium is wound before the first data is recorded onto the magnetic cartridge), and extending a predetermined distance from that position toward the end opposite the inner end (hereinafter also referred to as the "outer end" (BOT)). 1, the inner side of the reel refers to the area starting from the end attached to the tape reel 13 before the first data recording (hereinafter also referred to as the "inner end of tape" (EOT)) and extending a predetermined distance from that position toward the end opposite the inner end (hereinafter also referred to as the "outer end of tape" (BOT)). The outer side of the reel refers to the area starting from the outer end of the two ends of the magnetic recording medium and extending a predetermined distance from that position toward the inner end. 18, the inner side of the reel refers to the area starting from the end attached to the reel 407 before the first data recording (hereinafter also referred to as the "inner end of the tape" (EOT)) and extending a predetermined distance from that position toward the end opposite the inner end (hereinafter also referred to as the "outer end of the tape" (BOT). The outer side of the reel refers to the area starting from the outer end of the two ends of the magnetic recording medium and extending a predetermined distance from that position toward the inner end.

[0019] The inside and outside winding sides will be described in more detail with reference to Figure 27. Figure 27 is a schematic diagram showing how the entire length of a magnetic tape is divided into four equal parts from the inside end of the winding (EOT) to the outside end of the winding (BOT). As shown in Figure 27, from EOT to BOT, the entire length of the tape is divided into four parts, area D, area C, area B, and area A. In this specification, area A in Figure 27 is referred to as the outside winding side, and area D is referred to as the inside winding side.

[0020] In the magnetic recording cartridge of the present technology, the width change amount is 0 ppm at either of two portions sandwiching the center line of the entire length of the magnetic recording medium when the entire length of the magnetic recording medium is divided into four equal parts. This will be described with reference to FIG. 27. FIG. 27 is a schematic diagram showing the entire length of the magnetic tape divided into four equal parts from the end of tape (EOT) to the base of tape (BOT). As shown in FIG. 27, from the EOT to the BOT, the entire length of the tape is divided into four portions, namely, area D, area C, area B, and area A. As shown in FIG. 27, the center line of the entire length of the magnetic tape is located between area B and area C and is the boundary line separating area B and area C, and the two portions sandwiching the center line are area B and area C. In the magnetic recording cartridge of the present technology, the width change amount is 0 ppm at either area B or area C. The method for measuring the amount of width change will be explained in 2.(5) below.

[0021] In the magnetic recording cartridge of the present technology, the width change amount Δin on the inside of the roll may be a positive value. Here, the width change amount Δin on the inside of the roll means the maximum width change amount on the inside of the roll. A positive width change amount Δin on the inside of the roll means that the width on the inside of the roll after storage is wider than the width in the initial state. In the magnetic recording cartridge of the present technology, the width change amount Δout on the outside of the winding may be a negative value. Here, the width change amount Δout on the outside of the winding means the minimum value of the width change amount on the outside of the winding. A negative value for the width change amount Δout on the outside of the winding means that the width on the outside of the winding after storage is narrower than the width in the initial state. Furthermore, when the entire length of the magnetic recording medium in the longitudinal direction is taken as 100%, preferably at a position 25% to 75% from the outside end (BOT), the width change Δ of the magnetic recording medium after storage at 65°C for 360 hours may be 0 ppm. In the magnetic recording medium shown in Figure 27, the width change Δ of the magnetic recording medium after storage at 65°C for 360 hours may be 0 ppm at either region B or region C, which corresponds to a position 25% to 75% from the outside end (BOT). Furthermore, in a magnetic recording medium whose total length is divided into four equal parts as shown in FIG. 27, the average value of the width change Δ in region A, which corresponds to the outer 1 / 4 of the winding, may preferably be a negative value, and the average value of the width change Δ in region D, which corresponds to the inner 1 / 4 of the winding, may preferably be a positive value. In the magnetic recording medium, (width change amount Δin on the inside of the winding) - (width change amount Δout on the outside of the winding) may be 800 ppm or less.

[0022] The magnetic recording medium included in the magnetic recording cartridge of the present technology is preferably a long magnetic recording medium, and may be, for example, a magnetic recording tape (particularly a long magnetic recording tape).

[0023] The magnetic recording medium included in the magnetic recording cartridge of the present technology may have a magnetic layer, a base layer, and a back layer, and may include other layers in addition to these layers. The other layers may be selected appropriately depending on the type of magnetic recording medium. The magnetic recording medium may be, for example, a coating-type magnetic recording medium or a vacuum thin-film magnetic recording medium. The coating-type magnetic recording medium will be described in more detail in Section 2 below. The vacuum thin-film magnetic recording medium will be described in more detail in Section 3 below. For layers included in the magnetic recording medium other than the above three layers, please refer to these descriptions.

[0024] The magnetic recording medium included in the magnetic recording cartridge of the present technology may have, for example, at least one data band and at least two servo bands. The number of data bands may be, for example, 2 to 10, particularly 3 to 6, and more particularly 4 or 5. The number of servo bands may be, for example, 3 to 11, particularly 4 to 7, and more particularly 5 or 6. These servo bands and data bands may be arranged, for example, so as to extend in the longitudinal direction of a long magnetic recording medium (particularly a magnetic recording tape), particularly so as to be substantially parallel. The data band and the servo band may be provided on the magnetic layer. An example of a magnetic recording medium having such a data band and servo band is a magnetic recording tape conforming to the LTO (Linear Tape-Open) standard. That is, the magnetic recording medium may be a magnetic recording tape conforming to the LTO standard. For example, the magnetic recording medium may be a magnetic recording tape conforming to the LTO9 standard or later (e.g., LTO10, LTO11, or LTO12). The width of the long magnetic recording medium (particularly magnetic recording tape) can be, for example, 5 mm to 30 mm, particularly 7 mm to 25 mm, more particularly 10 mm to 20 mm, and even more particularly 11 mm to 19 mm. The length of the long magnetic recording medium (particularly magnetic recording tape) can be, for example, 500 m to 1500 m. For example, a tape conforming to the LTO8 standard has a width of 12.65 mm and a length of 960 m.

[0025] 2. First embodiment (example of magnetic recording cartridge including coating-type magnetic recording medium)

[0026] (1) Structure of magnetic recording cartridge

[0027] [Magnetic recording cartridge]

[0028] First, the configuration of a magnetic recording cartridge according to the present technology will be described with reference to Fig. 1. Fig. 1 is an exploded perspective view showing an example of a magnetic recording cartridge 10 according to the present technology. In the description of the present technology, a magnetic recording cartridge conforming to the LTO standard will be used as the magnetic recording cartridge 10.

[0029] As shown in Figure 1, a magnetic recording cartridge 10 includes a cartridge case 11, a tape reel 13, and a magnetic recording medium, namely, magnetic tape 1. The cartridge case 11 is constructed by joining an upper shell 11a and a lower shell 11b with a plurality of screw members. Inside the cartridge case 11, a single tape reel 13 around which the magnetic tape 1 is wound is rotatably housed.

[0030] A ring-shaped chucking gear (not shown) that engages with a spindle 31 (see FIG. 6) of the tape drive device 30 is formed in the center of the bottom of the tape reel 13. This chucking gear is exposed to the outside through an opening 14 formed in the center of the lower shell 11b. An annular metal plate 15 that is magnetically attracted to the spindle 31 is fixed to the inner periphery of this chucking gear.

[0031] A reel spring 16, a reel lock member 17, and a spider 18 are disposed between the inner surface of the upper shell 11a and the tape reel 13. These constitute a reel lock mechanism that prevents the tape reel 13 from rotating when the magnetic recording cartridge 10 is not in use.

[0032] A tape pull-out opening 19 for pulling out one end of the magnetic tape 1 to the outside is provided on one side wall of the cartridge case 11. A slide door 20 for opening and closing the tape pull-out opening 19 is disposed inside this side wall. The slide door 20 is configured to slide in the direction of opening the tape pull-out opening 19 against the biasing force of a torsion spring 21 by engaging with a tape loading mechanism (not shown) of the tape drive device 30.

[0033] A leader pin 22 is fixed to one end of the magnetic tape. The leader pin 22 is configured to be detachable from a pin holder 23 provided on the inside of the tape pull-out opening 19. The pin holder 23 is equipped with elastic holders 24 that elastically hold the upper and lower ends of the leader pin 22 on the inner surface of the top wall (inner surface of the upper shell 11a) and the inner surface of the bottom wall (inner surface of the lower shell 11b) of the cartridge case 11, respectively.

[0034] Inside the other side wall of the cartridge case 11, there is arranged a safety tab 25 for preventing accidental erasure of information recorded on the magnetic tape 1, as well as a cartridge memory 9 that can read and write contents related to the data recorded on the magnetic tape 1 without contact.

[0035] Fig. 2 is a schematic diagram of the magnetic tape 1 as seen from the side, and Fig. 3 is a schematic diagram of the magnetic tape 1 as seen from above (the magnetic layer 43 side). As shown in Figs. 2 and 3, the magnetic tape 1 is configured in the form of a long tape that is long in the longitudinal direction (X-axis direction), short in the width direction (Y-axis direction), and thin in the thickness direction (Z-axis direction).

[0036] The magnetic tape 1 includes a tape-shaped base layer 41 that is long in the longitudinal direction (X-axis direction), a non-magnetic layer (underlayer) 42 provided on one main surface of the base layer 41, a magnetic layer 43 provided on the non-magnetic layer (underlayer) 42, and a back layer 44 provided on the other main surface of the base layer 41. Note that the back layer 44 may be provided as needed, and may be omitted. The magnetic tape 1 may be a perpendicular recording type magnetic recording medium, or may be a longitudinal recording type magnetic recording medium. The layers that make up the magnetic tape 1 will be described in detail later.

[0037] 3, the magnetic layer 43 has a plurality of data bands d (data bands d0 to d3) that are long in the longitudinal direction (X-axis direction) in which data is written, and a plurality of servo bands s (servo bands s0 to s4) that are long in the longitudinal direction in which servo patterns 6 are written. The servo bands s are arranged at positions that sandwich each data band d in the width direction (y-axis direction).

[0038] In this technology, the ratio of the area of ​​the servo bands s to the area of ​​the entire surface of the magnetic layer 43 is typically 4.0% or less. The width of the servo bands s is, for example, 96 μm or less for a ½ inch tape width. The ratio of the area of ​​the servo bands s to the area of ​​the entire surface of the magnetic layer 43 can be measured, for example, by developing the magnetic tape 1 with a developer such as a ferricolloid developer, and then observing the developed magnetic tape 1 with an optical microscope.

[0039] 3 shows an example in which the number of data bands d is 4 and the number of servo bands s is 5. Note that the number of data bands d and the number of servo bands s can be changed as appropriate.

[0040] The data band d is elongated in the longitudinal direction and includes a plurality of recording tracks 5 aligned in the width direction. The number of recording tracks 5 included in one data band d is, for example, about 1,000 to 2,000. Data is recorded along these recording tracks 5 within the recording tracks 5. The length of one bit in the longitudinal direction of the data recorded in the data band d is, for example, 48 nm or less. The servo band s includes a servo pattern 6 of a predetermined shape that is recorded by a servo pattern recording device (see FIG. 9) described later.

[0041] Here, the number of recording tracks 5 of LTO-standard magnetic tape 1 has increased with each generation, dramatically improving recording capacity. For example, the original LTO-1 had 384 recording tracks 5, but the numbers of recording tracks 5 for LTO-2 to LTO-8 have increased to 512, 704, 896, 1280, 2176, 3584, and 6656, respectively. Similarly, data storage capacity was 100 GB (gigabytes) for LTO-1, but increased to 200 GB, 400 GB, 800 GB, 1.5 TB (terabytes), 2.5 TB, 6.0 TB, and 12 TB, respectively, for LTO-2 to LTO-8.

[0042] In this embodiment, the number of recording tracks 5 and the recording capacity are not particularly limited and can be changed as appropriate. However, it is advantageous to apply this to a magnetic tape 1 that has a large number of recording tracks 5 and a large recording capacity (for example, 6656 or more tracks, 12 TB or more: LTO-8 or later) and is susceptible to variations in the width of the magnetic tape.

[0043] [Data band and servo band]

[0044] FIG. 4 is an enlarged view of a recording track 5 in a data band d. As shown in FIG. 4, the recording tracks 5 are elongated in the longitudinal direction, aligned in the width direction, and each track has a predetermined recording track width (track pitch) Wd in the width direction. This recording track width Wd is typically 2.0 μm or less. Note that the recording track width Wd can be measured, for example, by developing the magnetic layer 43 of the magnetic tape 1 using a developer such as a ferricolloid developer and then observing the developed magnetic layer 43 of the magnetic tape 1 with an optical microscope. Alternatively, as a measurement method using a drive head, the recording track width Wd can be measured from the change in output when the drive head is set in a read-while-write state to ignore fluctuations during tape running, and the azimuth of the drive head is changed. (IEEE_Sept1996_Crosstrack Profiles of Thin Film MR Tape Heads Using the Azimuth Displacement Method)

[0045] FIG. 5 is an enlarged view of a servo pattern 6 written in a servo band s. As shown in FIG. 5, the servo pattern 6 includes a plurality of stripes that are inclined at a predetermined azimuth angle α with respect to the width direction (Y-axis direction), as will be described in detail later. These stripes are classified into a first group of stripes 61 that are inclined clockwise with respect to the width direction (Y-axis direction) and a second group of stripes 62 that are inclined counterclockwise with respect to the width direction (Y-axis direction). Each of the first group of stripes 61 and the second group of stripes 62 typically includes four or five stripes. The shape of the servo pattern 6 can be measured, for example, by developing the magnetic layer 43 of the magnetic tape 1 using a developer such as a ferricolloid developer and then observing the developed magnetic layer 43 of the magnetic tape 1 with an optical microscope.

[0046] 5, broken lines indicate servo trace lines T that are lines traced by a servo read head 132 (see FIG. 7) described later on the servo pattern 6. The servo trace lines T are set along the longitudinal direction (X-axis direction) and are set at predetermined intervals Ps in the width direction.

[0047] The number of servo trace lines T per servo band s is, for example, about 30 to 60. The spacing Ps between two adjacent servo trace lines T is the same as the recording track width Wd, and is, for example, 2.0 μm or less. Here, the spacing Ps between two adjacent servo trace lines T is a value that determines the recording track width Wd. In other words, if the spacing Ps between the servo trace lines T is narrowed, the recording track width Wd becomes smaller and the number of recording tracks 5 included in one data band d increases. As a result, the data recording capacity increases.

[0048] (2) Recording and playback device

[0049] 6 is a diagram showing a recording / reproducing device 30. The recording / reproducing device 30 is a data recording / reproducing device capable of recording data on a magnetic tape 1 or reproducing data recorded on the magnetic tape 1.

[0050] 6, the recording / reproducing device 30 is configured so that it can be loaded with a magnetic recording cartridge 10. The recording / reproducing device 30 is configured so that it can be loaded with one magnetic recording cartridge 10.

[0051] The recording / reproducing device 30 includes a spindle 31, a take-up reel 32, a spindle drive device 33, a reel drive device 34, a plurality of guide rollers 35, a drive head 36, a reader / writer 37, and a control device 38. The recording / reproducing device 30 may further include a thermometer 39, a hygrometer 40, etc.

[0052] The spindle 31 has a head portion that engages with a chucking gear of the tape reel 13 through an opening 14 formed in the lower shell 11b of the magnetic recording cartridge 10. The spindle 31 lifts the tape reel 13 a predetermined distance against the biasing force of the reel spring 16, thereby releasing the reel lock function of the reel lock member 17. As a result, the tape reel 13 is rotatably supported inside the cartridge case 11 by the spindle 31.

[0053] The spindle drive device 33 rotates the spindle 31 in response to a command from the control device 38. The take-up reel 32 is configured to be able to fix the leading end (leader pin 22) of the magnetic tape 1 pulled out from the magnetic recording cartridge 10 via a tape loading mechanism (not shown).

[0054] A plurality of guide rollers 35 guide the running of the magnetic tape 1 so that the tape path formed between the magnetic recording cartridge 10 and the take-up reel 32 has a predetermined relative positional relationship with the drive head 36. The reel drive device 34 rotates the take-up reel 32 in response to commands from the control device 38.

[0055] When data is recorded on / played back from the magnetic tape 1, the spindle 31 and take-up reel 32 are rotated by the spindle drive device 33 and the reel drive device 34, causing the magnetic tape 1 to run. The magnetic tape 1 can run back and forth in the forward direction indicated by arrow A1 in Fig. 6 (the direction in which the tape is unwound from the tape reel 13 side to the take-up reel 32 side), and in the reverse direction indicated by arrow A2 (the direction in which the tape is rewound from the take-up reel 32 side to the tape reel 13 side).

[0056] In this embodiment, the tension in the longitudinal direction (X-axis direction) of the magnetic tape 1 during data recording / playback can be adjusted by controlling the rotation of the spindle 31 by the spindle drive device 33 and the rotation of the take-up reel 32 by the reel drive device 34. The tension of the magnetic tape 1 may be adjusted by controlling the movement of the guide roller 35, a tension control unit including a dancer roller, or the like, instead of (or in addition to) controlling the rotation of the spindle 31 and the take-up reel 32.

[0057] The reader / writer 37 is configured to be able to record management information in the cartridge memory 9 in response to a command from the control device 38. The reader / writer 37 is also configured to be able to read management information from the cartridge memory 9 in response to a command from the control device 38. As a communication method between the reader / writer 37 and the cartridge memory 9, for example, the ISO14443 method is adopted.

[0058] The control device 38 includes, for example, a control unit, a storage unit, a communication unit, etc. The control unit is configured, for example, with a CPU (Central Processing Unit) etc., and controls each unit of the recording / playback device 30 in an integrated manner in accordance with a program stored in the storage unit.

[0059] The storage unit includes a non-volatile memory in which various data and programs are recorded, and a volatile memory used as a work area for the control unit. The various programs may be read from a portable recording medium such as an optical disk or semiconductor memory, or may be downloaded from a server device on a network. The storage unit temporarily or non-temporarily stores information from the cartridge memory 9 read by the reader / writer 27, outputs from the thermometer 39 and the hygrometer 40, etc. The communication unit is configured to be able to communicate with other devices such as a PC (Personal Computer) or a server device.

[0060] The drive head 36 is configured to be able to record data on the magnetic tape 1 in response to a command from the control device 38. The drive head 36 is also configured to be able to reproduce data written on the magnetic tape 1 in response to a command from the control device 38.

[0061] The drive head 36 is configured with a head unit having, for example, two servo read heads, a plurality of data write / read heads, etc. Figure 7 is a schematic diagram of the drive head 36 as viewed from the bottom (tape running surface).

[0062] 7, the drive head 36 includes a first drive head portion 36a and a second drive head portion 36b. The first drive head portion 36a and the second drive head portion 36b are configured symmetrically in the X'-axis direction (the running direction of the magnetic tape 1 (the X-axis direction in FIG. 3)). The first drive head portion 36a and the second drive head portion 36b are configured to be movable in the width direction of the magnetic tape 1 (the Y-axis direction in FIG. 3).

[0063] The first drive head unit 36a is a drive head that is used when the magnetic tape 1 runs in the forward direction (direction A1 in FIG. 6). On the other hand, the second drive head unit 36b is a drive head that is used when the magnetic tape 1 runs in the reverse direction (direction A2 in FIG. 6). The first drive head unit 36a and the second drive head unit 36b basically have the same configuration, so the first drive head unit 36a will be described as a representative example.

[0064] The first drive head unit 36 ​​a has a head body 131 , two servo read heads 132 , and a plurality of data write / read heads 133 .

[0065] The servo read heads 132 are provided one on each end of the head body 131 in the width direction (Y'-axis direction in FIG. 7). MR elements include anisotropic magnetoresistive effect elements (AMR: Anisotropic Magneto-Resistive effect elements), giant magnetoresistive effect elements (GMR: Giant Magneto-Resistive effect elements), tunnel magnetoresistive effect elements (TMR: Tunnel Magneto-Resistive effect elements), etc. The spacing between the two servo read heads 132 in the width direction (Y'-axis direction) is approximately the same as the distance between adjacent servo bands s on the magnetic tape 1, and details of this will be described later.

[0066] The data write / read heads 133 are arranged at equal intervals along the width direction (Y'-axis direction). Each data write / read head 133 is arranged at a position sandwiched between two servo read heads 132. The number of data write / read heads 133 is, for example, about 20 to 40, but is not particularly limited to this number.

[0067] The data write / read head 133 includes a data write head 134 and a data read head 135. The data write head 134 is configured to be able to record a data signal on the data band d of the magnetic tape 1 by using a magnetic field generated from the magnetic gap. The data read head 135 is configured to be able to reproduce the data signal by reading the magnetic field generated from the magnetic information recorded on the data band d of the magnetic tape 1 using an MR element (MR: Magneto Resistive effect) or the like. Examples of MR elements include an anisotropic magnetoresistive effect element (AMR: Anisotropic Magneto Resistive effect), a giant magnetoresistive effect element (GMR: Giant Magneto Resistive effect), a tunnel magnetoresistive effect element (TMR: Tunnel Magneto Resistive effect), and the like.

[0068] In the first drive head unit 36a, the data write head 134 is arranged to the left of the data read head 135 (upstream when the magnetic tape 1 flows in the forward direction). On the other hand, in the second drive head unit 36b, the data write head 134 is arranged to the right of the data read head 135 (upstream when the magnetic tape 1 flows in the reverse direction). The data read head 135 is capable of reproducing a data signal immediately after the data write head 134 writes the data signal to the magnetic tape 1.

[0069] Fig. 8 is a diagram showing the state when the first drive head unit 36a is recording / reproducing a data signal. Note that the example shown in Fig. 8 shows the state when the magnetic tape 1 is running in the forward direction (A1 direction).

[0070] 8, when the first drive head unit 36a records / reproduces a data signal, one of the two servo read heads 132 is positioned on one of two adjacent servo bands s and reads the servo pattern 6 on this servo band s. The other of the two servo read heads 132 is positioned on the other of the two adjacent servo bands s and reads the servo pattern 6 on this servo band s.

[0071] Based on the reproduced waveform of the servo pattern 6, the control device 38 determines whether the servo read head 132 is accurately tracing the target servo trace line T (see FIG. 5).

[0072] This principle will be explained below. As shown in Fig. 5, the first stripe group 61 and the second stripe group 62 in the servo pattern 6 are inclined in opposite directions with respect to the width direction (Y-axis direction). Therefore, on the upper servo trace line T, the distance between the first stripe group 61 and the second stripe group 62 in the longitudinal direction (X-axis direction) is relatively narrow. On the other hand, on the lower servo trace line T, the distance between the first stripe group 61 and the second stripe group 62 in the longitudinal direction (X-axis direction) is relatively wide.

[0073] Therefore, by calculating the difference between the time when the reproduced waveform of the first stripe group 61 is detected and the time when the reproduced waveform of the second stripe group 62 is detected, the current position of the servo read head 132 in the width direction (Y-axis direction) relative to the magnetic tape 1 can be determined.

[0074] Therefore, the control device 38 can determine whether the servo read head 132 is accurately tracing the target servo trace line T based on the reproduced waveform of the servo pattern 6. If the servo read head 132 is not accurately tracing the target servo trace line T, the control device 38 moves the drive head 36 in the width direction (Y'-axis direction) to adjust the position of the drive head 36. A method for measuring the servo trace line T traced by the servo read head 132 will be described later with reference to FIG. 20.

[0075] Returning to FIG. 8, if the magnetic tape 1 fluctuates in the width direction while it is running, the data write / read head 133 adjusts its position to follow the servo trace line T and records a data signal in the recording track 5.

[0076] Here, when the magnetic tape 1 is completely pulled out from the magnetic recording cartridge 10, the magnetic tape 1 now runs in the reverse direction (A2 direction). At this time, the second drive head portion 36b is used as the drive head 36. The servo trace line T used is the servo trace line T adjacent to the previous servo trace line T. In this case, the drive head 36 is moved in the width direction (Y'-axis direction) by the interval Ps between the servo trace lines T (=recording track width Wd). In this case, a data signal is recorded on a recording track 5 adjacent to the recording track 5 on which the data signal was previously recorded.

[0077] In this way, the magnetic tape 1 is reciprocated many times, with its running direction changed between forward and reverse, and data signals are recorded on the recording tracks 5. For example, assume that there are 50 servo trace lines T and the first drive head unit 36a (or the second drive head unit 36b) includes 32 data write / read heads 133. In this case, the number of recording tracks 5 included in one data band d is 50 x 32 = 1,600, and in order to record data signals on all of these recording tracks 5, the magnetic tape 1 must be reciprocated 25 times.

[0078] [Servo pattern recording device]

[0079] Next, a description will be given of the configuration of a servo pattern recording device that records servo patterns 6 on servo bands s of the magnetic tape 1. Fig. 9 is a front view showing the servo pattern recording device 100 according to an embodiment of the present technology. Fig. 10 is a partially enlarged view showing a part of the servo pattern recording device 100.

[0080] The servo pattern recording device 100 includes, in order from the upstream side in the transport direction of the magnetic tape 1, a feed roller 111, a pre-processing unit 112, a servo write head 113, a reproducing head unit 114, and a take-up roller 115. The servo pattern recording device 100 further includes a drive unit 120 and a controller 130. The controller 130 includes a control unit that comprehensively controls each unit of the servo pattern recording device 100, a recording unit that stores various programs and data required for processing by the control unit, a display unit that displays data, an input unit for inputting data, etc.

[0081] The feed roller 111 is capable of rotatably supporting the rolled magnetic tape 1 (before the servo pattern 6 is recorded). The feed roller 111 is rotated in response to the driving of a driving source such as a motor, and feeds out the magnetic tape 1 downstream in response to the rotation.

[0082] The take-up roller 115 is capable of rotatably supporting the rolled magnetic tape 1 (after the servo pattern 6 is recorded). The take-up roller 115 rotates in synchronization with the feed-out roller 111 in response to the drive of a drive source such as a motor, and takes up the magnetic tape 1 on which the servo pattern 6 is recorded as it rotates. The feed-out roller 111 and the take-up roller 115 are capable of moving the magnetic tape 1 at a constant speed on the transport path.

[0083] The servo write head 113 is disposed, for example, above the magnetic tape 1 (on the magnetic layer 43 side). The servo write head 113 may also be disposed below the magnetic tape 1 (on the base layer 41 side). The servo write head 113 generates a magnetic field at a predetermined timing in response to a square wave pulse signal, and applies the magnetic field to a part of the magnetic layer 43 (after pre-processing) of the magnetic tape 1.

[0084] As a result, the servo write head 113 magnetizes a portion of the magnetic layer 43 in the first direction to record the servo pattern 6 on the magnetic layer 43 (see the black arrows in FIG. 10 for the magnetization direction). The servo write head 113 is capable of recording the servo pattern 6 on each of the five servo bands s0 to s4 when the magnetic layer 43 passes below the servo write head 113.

[0085] The first direction, which is the magnetization direction of the servo pattern 6, includes a perpendicular component perpendicular to the top surface of the magnetic layer 43. That is, in this embodiment, since perpendicularly oriented or non-oriented magnetic powder is included in the magnetic layer 43, the servo pattern 6 recorded in the magnetic layer 43 includes a perpendicular magnetization component.

[0086] The pre-processing unit 112 is disposed, for example, below the magnetic tape 1 (toward the base layer 41) and upstream of the servo write head 113. The pre-processing unit 112 may also be disposed above the magnetic tape 1 (toward the magnetic layer 43). The pre-processing unit 112 includes a permanent magnet 112a that can rotate around the Y-axis direction (the width direction of the magnetic tape 1) as the central axis of rotation. The shape of the permanent magnet 112a is, for example, cylindrical or polygonal prism, but is not limited to these.

[0087] Before the servo write head 113 records the servo pattern 6, the permanent magnet 112a applies a magnetic field to the entire magnetic layer 43 using a DC magnetic field, thereby demagnetizing the entire magnetic layer 43. This allows the permanent magnet 112a to magnetize the magnetic layer 43 in advance in a second direction opposite to the magnetization direction of the servo pattern 6 (see the white arrow in FIG. 10). By thus setting the two magnetization directions in opposite directions, the reproduced waveform of the servo signal obtained by reading the servo pattern 6 can be made symmetrical in the up-down direction (±). As a method for adjusting the second direction, for example, the rotation angle of the permanent magnet 112a may be set arbitrarily, the entire magnetic layer 43 may be demagnetized, and then the servo pattern 6 may be recorded on the magnetic layer 43, and the rotation angle of the permanent magnet 112a centered on the width direction of the magnetic tape 1 may be adjusted based on the slope of the reproduced waveform.

[0088] The reproducing head unit 114 is disposed downstream of the servo write head 113 and above the magnetic tape 1 (on the magnetic layer 43 side). The reproducing head unit 114 reads the servo pattern 6 from the magnetic layer 43 of the magnetic tape 1, which has been preprocessed by the preprocessing unit 112 and on which the servo pattern 6 has been recorded by the servo write head 113. The reproduced waveform of the servo pattern 6 read by the reproducing head unit 114 is displayed on the screen of the display unit. Typically, the reproducing head unit 114 detects magnetic flux generated from the surface of the servo band s when the magnetic layer 43 passes below the reproducing head unit 114. The magnetic flux detected at this time becomes the reproduced waveform of the servo pattern 6 as a servo signal.

[0089] [Servo pattern]

[0090] Next, the servo pattern 6 will be described in detail. The servo pattern 6 has a data structure that complies with the "ECMA-319 standard." Fig. 11(A) is a diagram showing the data structure of the LPOS word embedded in the servo pattern 6, and Fig. 11(B) is a diagram explaining the manufacturer word.

[0091] 11(A), a plurality of LPOS (Longitudinal position) words LW arranged consecutively in the longitudinal direction of the tape are embedded in the servo pattern 6. Each LPOS word LW is made up of 36 bits of data including an 8-bit synchronization mark Sy indicating its beginning, an LPOS value Ls consisting of six 4-bit pieces (24 bits in total) indicating a position (address) in the longitudinal direction of the tape, and 4-bit manufacturer data Tx.

[0092] The manufacturer data Tx forms a manufacturer word TW on the magnetic tape 1. As shown in Figure 11(B), the manufacturer word TW has a length of 97 pieces of manufacturer data Tx and is obtained by consecutively reading 97 LPOS words LW. The manufacturer word TW is constructed as follows: Manufacturer word TW:D,A0,A1,A0,A1,···,A0,A1

[0093] The first manufacturer data Tx, "D", is a symbol indicating the beginning of the manufacturer word TW, and contains 4 bits of data (typically "0001") converted using a specified table.

[0094] The second and subsequent 96 pieces of manufacturer data Tx consist of alternating "A0" and "A1" bits, with two adjacent "A0" and "A1" bits forming a symbol pair. Each pair of "A0" and "A1" bits contains one of 13 basic symbols (typically 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, and C) other than "D." These 13 basic symbols also consist of 4-bit data converted using the predetermined table. A single symbol (hereinafter also referred to as an LPOS record value) is identified based on the combination of two specific basic symbols (corresponding to the symbol pair) among the 13 basic symbols.

[0095] The LPOS record value consists of 8 bits of data. The two basic symbols that form a symbol pair may be homogeneous (e.g., 0,0) or heterogeneous (e.g., 0,1).

[0096] The 96 manufacturer data Tx configured as described above typically contain embedded information such as manufacturer information represented by the LPOS recorded value, management information such as the manufacturing date and serial number of the magnetic tape, and servo band identification information for identifying the servo band.

[0097] FIG. 12(A) is a schematic plan view showing an example of the arrangement of the servo patterns 6, and FIG. 12(B) is a diagram showing the reproduced waveform.

[0098] In a timing-based head tracking servo, the servo pattern includes a plurality of azimuthal slope patterns of two or more different shapes. The position of the servo read head 132 is recognized based on the time interval between reading two slope patterns of different shapes and the time interval between reading two slope patterns of the same shape. Based on the position of the servo read head 132 recognized in this way, the position of the drive head 36 in the width direction (Y-axis direction) of the magnetic tape 1 is controlled (see FIGS. 7 and 8).

[0099] As shown in Figure 12(A), the servo pattern 6 forms a servo frame SF having a first servo subframe SSF1 and a second servo subframe SSF2. The servo frames SF are arranged consecutively at predetermined intervals along the longitudinal direction of the tape. Each servo frame SF encodes one bit, either "1" or "0." In other words, one servo frame SF corresponds to one bit.

[0100] The first servo subframe SSF1 is composed of an A burst 6a and a B burst 6b. The A burst 6a is composed of five straight line patterns (corresponding to the first stripe group 61 in FIG. 5) that are inclined in a first direction relative to the longitudinal direction of the tape, and the B burst 6b is composed of five straight line patterns (corresponding to the second stripe group 62 in FIG. 5) that are inclined in a second direction opposite to the first direction relative to the longitudinal direction of the tape.

[0101] On the other hand, the second servo subframe SSF2 is composed of a C burst 6c and a D burst 6d. The C burst 6c is composed of four straight line patterns inclined in the first direction (corresponding to the first stripe group 61 in FIG. 5), and the D burst 6d is composed of four straight line patterns inclined in the second direction (corresponding to the second stripe group 62 in FIG. 5).

[0102] The lengths of the servo frame SF and each of the servo subframes SSF1 and SSF2, and the intervals between the sloped portions that slope each of the bursts 6a to 6d can be set arbitrarily according to the type and specifications of the magnetic tape.

[0103] The reproduced waveform of the servo pattern 6 typically exhibits a burst waveform as shown in Figure 12(B), where signal S6a corresponds to A burst 6a, signal S6b corresponds to B burst 6b, signal S6c corresponds to C burst 6c, and signal S6d corresponds to D burst 6d.

[0104] In a timing-based head tracking servo, a position error signal (PES) is generated by reading servo patterns 6 on two servo bands adjacent to one data band, and the recording / playback head is appropriately positioned relative to the recording track within that data band. Typically, the servo patterns 6 are read from a magnetic tape 1 traveling at a predetermined speed, and the ratio of the distance (time interval) AC between A bursts 6a and C bursts 6c, which are arrays of inclined patterns with the same shape, to the distance (time interval) AB between A bursts 6a and B bursts 6b, which are arrays of inclined patterns with different shapes (or the ratio of the distance CA between C bursts 6c and A bursts 6a to the distance CD between C bursts 6c and D bursts 6d) is calculated, and the drive head 36 is moved in the tape width direction (Y-axis direction) until the calculated value becomes a preset value determined for each recording track (see Figure 8).

[0105] [Data band identification]

[0106] A different combination of servo band identification information is written to each servo band s (s0 to s4) for each data band. For example, the combination of servo band identification information obtained from two servo bands s2 and s3 adjacent to data band d0 is different from the combination of servo band identification information obtained from servo bands s1 and s2 adjacent to data band d1, the combination of servo band identification information obtained from two servo bands s3 and s4 adjacent to data band d2, and the combination of servo band identification information obtained from two servo bands s0 and s1 adjacent to data band d3. In this way, by making the servo band identification information obtained from two servo bands adjacent to one data band different from the servo band identification information obtained from two servo bands adjacent to another data band, it becomes possible to identify each individual data band.

[0107] In this embodiment, two types of servo bands are used to identify the data bands d0 to d4 to be recorded / reproduced. As described above, servo band identification information is embedded in the servo bands. The servo band identification information is multi-bit information, and is embedded in predetermined positions of the second and subsequent 96 pieces of manufacturer data Tx in the manufacturer word TW. The servo band identification information is typically 4 bits, but may be 8 bits (a combination of the symbol pair "A0" and "A1"), or may be a number of bits other than 4 or 8 bits.

[0108] In this embodiment, the two types of servo bands include a first servo band in which first servo band identification information is recorded and a second servo band in which second servo band identification information is recorded. The first servo band identification information is 4-bit information (e.g., "1001"), and the second servo band identification information is 4-bit information (e.g., "0111") different from the first servo band identification information.

[0109] The combination of the codes "0" and "1" that make up the first and second servo band identification information is identified from the reproduced waveform of the servo pattern 6. In other words, the reproduced waveform of the servo pattern 6 corresponds to a modulated wave of the codes "0" and "1", and the first and second servo band identification information is read out by demodulating the reproduced waveform and combining, for example, four bits. The first and second servo band identification information will be described below with reference to FIGS. 13 and 14.

[0110] 13A and 13B are schematic diagrams showing configuration examples of a servo pattern (hereinafter also referred to as a first servo pattern 601) in which first servo band identification information is embedded and a servo pattern (hereinafter also referred to as a second servo pattern 602) in which second servo band identification information is embedded. As shown in the figures, both the first servo pattern 601 and the second servo pattern 602 are composed of a combination of two types of servo frames SF, including a servo frame SF1 representing one code (e.g., "1") and a servo frame SF0 representing the other code (e.g., "0"). Each servo frame SF1 and SF0 have in common the fact that they use a servo frame SF consisting of a first servo subframe SSF1 and a second servo subframe SSF2 as a constituent unit, but the first servo subframe SSF1 (A burst 6a and B burst 6b) are different from each other.

[0111] As shown in FIG. 13A, in a servo frame SF1 representing a code "1," when the five slope patterns constituting the A burst 6a and the B burst 6b are, from left to right in the figure, the first slope portion, the second slope portion, the third slope portion, the fourth slope portion, and the fifth slope portion, the second slope portion and the fourth slope portion are positioned so as to be biased toward the first slope portion and the fifth slope portion, respectively. In contrast, as shown in FIG. 13B, in a servo frame SF0 representing a code "0," the arrangement intervals of some of the slope patterns constituting the A burst 6a and the B burst 6b are different from those in the servo frame SF1. In the illustrated example, the five slope patterns constituting the A burst 6a and the B burst 6b are positioned so as to be biased toward the third slope portion, the second slope portion, and the fourth slope portion are positioned so as to be biased toward the third slope portion. Therefore, for the A burst 6a and the B burst 6b in the servo frame SF0, the distance between the second inclined portion and the third inclined portion, and between the third inclined portion and the fourth inclined portion, is the smallest, and the distance between the first inclined portion and the second inclined portion, and between the fourth inclined portion and the fifth inclined portion is the largest.

[0112] 14A and 14B show the reproduced waveforms SP1 and SP2 of the first servo pattern 601 and the second servo pattern 602, respectively. The reproduced waveforms of each servo frame SF1 and SF0 are composed of burst signals having peaks at positions corresponding to the slopes of each of the burst portions 6a to 6d. As described above, the configuration of the A burst 6a and the B burst 6b of the servo frame SF0 is different from that of the A burst 6a and the B burst 6b of the servo frame SF1, and therefore the peak positions of the burst signals S6a and S6b are shifted corresponding to the intervals between the different slopes. Therefore, by detecting the location where the peak positions are shifted, as well as the amount and direction of the shift, it is possible to read the information written in the servo frame SF. Here, for example, the servo frame SF1 shown in FIG. 14A represents one bit "1," and the servo frame SF0 shown in FIG. 14B represents another bit "0." By arbitrarily combining, for example, four bits of these two servo frames SF1 and SF0, first and second servo band identification information can be configured.

[0113] 10, the servo pattern recording device 100 has a drive unit 120 that drives the servo write head 113. Fig. 15 is a perspective view that schematically shows the configuration of the servo write head 113, and Fig. 16 is a block diagram showing the configuration of the drive unit 120.

[0114] 15, the servo write head 113 has a plurality of head blocks h0 to h4 for recording servo patterns 6 on each of the servo bands s0 to s4 of the magnetic tape 1. The head blocks h0 to h4 are joined to one another via an adhesive layer hs. Each of the head blocks h0 to h4 forms a recording section disposed corresponding to each of the servo bands s0 to s4 of the magnetic tape 1, and has a magnetic gap g for recording a servo pattern on each of the servo bands.

[0115] The magnetic gap g consists of a pair of straight lines (" / " and "\") that are inclined in opposite directions, with one straight line " / " recording the A burst 6a and C burst 6c, and the other straight line "\" recording the B burst 6b and D burst 6d. The magnetic gaps g of each head block h1 to h5 are aligned on an axis parallel to the longitudinal direction of the servo write head 113. The head blocks h0 to h4 are magnetically separated from each other and are configured to be able to record different types of servo patterns 6 simultaneously in two or more servo bands.

[0116] 16, the servo write head 113 includes a converter 121 that converts a servo signal into pulse information based on the output from the drive unit 130 (see FIG. 9), a signal generator 122 that generates a pulse signal based on the output from the converter 121, and an amplifier 123 that amplifies the generated pulse signal. A plurality of signal generators 122 and amplifiers 123 are provided corresponding to each of the head blocks h0 to h4, and are configured to be able to output a pulse signal specific to the head blocks h0 to h4 of each servo write head 113.

[0117] The controller 130 includes a memory that stores data relating to the positions of the servo bands where the first servo band identification information should be recorded (s0, s1, s4 in this example) and the positions of the servo bands where the second servo band identification information should be recorded (s2, s3 in this example). The controller 130 controls the drive unit 120 based on the data stored in the memory.

[0118] The converter 121 outputs information corresponding to the servo band identification information to be recorded in each of the servo bands s0 to s4 to the signal generators 122 corresponding to each of the head blocks h0 to h4. In this embodiment, the converter 121 outputs a first pulse signal PS1 for recording a first servo pattern 601 (FIG. 13A) including the first servo band identification information in the head blocks h0, h1, and h4 corresponding to the servo bands s0, s1, and s4, and outputs a second pulse signal PS2 for recording a second servo pattern 602 (FIG. 13B) including the second servo band identification information in the head blocks h2 and h3 corresponding to the servo bands s2 and s3.

[0119] 17A and 17B show schematic diagrams of the recording signal waveforms of the first servo subframe SSF1 in the first pulse signal PS1 and the second pulse signal PS2, respectively. As shown in the figures, the first and second pulse signals PS1 and PS2 include a first pulse group SPF1 consisting of five pulse groups and a second pulse group SPF2 consisting of four pulse groups. The first pulse group SPF1 is a signal for recording each slope portion of the A6 burst 6a, and the second pulse group SPF2 is a signal for recording each slope portion of the B burst 6b.

[0120] As shown in the figure, the rise times of the second and fourth pulses in the first pulse group SPF1 are different between the first pulse signal PS1 and the second pulse signal PS2, with the second pulse rising later and the fourth pulse rising earlier in pulse signal PS2 than in pulse signal PS1. This results in a first servo subframe SSF1 in which the arrangement intervals of the slopes of the A6 bursts 6a are partially different from each other, as shown in Figures 13(A) and 13(B).

[0121] Furthermore, the first pulse signal PS1 and the second pulse signal PS2 are transmitted to the head blocks h0 to h4 in the same phase (at the same timing), so that in each of the head blocks h0 to h4, a first servo pattern 601 (first servo band identification information) is recorded in the servo bands s0, s1, and s4, and a second servo pattern 602 (second servo band identification information) is recorded in the same phase in the servo bands s2 and s3.

[0122] [About fluctuations in tape width]

[0123] Incidentally, magnetic tape 1 is generally manufactured through processes such as coating a base film (base layer 41) with a magnetic material, calendering, cutting, and recording of servo patterns 6. These processes are performed while the base film is being wound under a constant tension, so the completed magnetic tape 1 has internal strain, and as this internal strain relaxes over time, the width of the magnetic tape 1 tends to expand. Furthermore, in storage and use environments at high temperatures of 60°C or higher, tension causes creep, resulting in longitudinal expansion. Therefore, the tape tends to expand in width on the inside of the winding where no tension is applied, due to the overlap of strain relaxation and widthwise creep caused by winding pressure. On the outside of the winding, the opposing phenomena of creep due to longitudinal tension, which causes widthwise shrinkage, and strain relaxation, combine to determine whether the width expands or contracts depending on the condition of the magnetic tape. In particular, in recent magnetic tapes where high capacity is required, the total thickness of the tape is thinned due to thinner base films and coating thicknesses, and the number of times the magnetic tape is wound around a reel is increased, which increases the surface pressure due to tight winding on the inside of the reel and increases the fluctuation in the width dimension of the magnetic tape. As the track width becomes narrower due to higher capacity, the impact of fluctuation in the width direction becomes even greater.

[0124] For this reason, when recording or reproducing data using a recording / reproducing device, even if the magnetic tape is run with the same tension as when the servo patterns were recorded, the width of the magnetic tape may increase from the width of the magnetic tape when the servo patterns were recorded. In this case, the spacing between adjacent servo bands changes, which causes fluctuations in the spacing of the servo patterns recorded on these servo bands, making it difficult to achieve the desired tracking control. This problem can become more pronounced as magnetic tape becomes thinner in recent years due to the increasing recording capacity.

[0125] (3) Configuration of Modified Magnetic Recording Cartridge

[0126] [Magnetic recording cartridge]

[0127] In the embodiment of the magnetic recording cartridge described above, the magnetic recording cartridge was described as a one-reel type cartridge, but the magnetic recording cartridge of the present technology may also be a two-reel type cartridge. That is, the magnetic recording cartridge of the present technology may have one or more (e.g., two) reels on which the magnetic tape is wound. Below, a modified example of the magnetic recording cartridge of the present technology having two reels will be described with reference to FIG. 18.

[0128] 18 is an exploded perspective view showing an example of the configuration of a two-reel type cartridge 421. Cartridge 421 includes an upper half 402 made of synthetic resin, a transparent window member 423 fitted into and fixed to a window 402a opened in the top surface of upper half 402, a reel holder 422 fixed to the inside of upper half 402 to prevent reels 406 and 407 from floating up, a lower half 405 corresponding to upper half 402, reels 406 and 407 stored in a space formed when upper half 402 and lower half 405 are combined, magnetic tape MT1 wound on reels 406 and 407, a front lid 409 that closes a front opening formed when upper half 402 and lower half 405 are combined, and a back lid 409A that protects magnetic tape MT1 exposed in this front opening.

[0129] The reel 406 includes a lower flange 406b having a cylindrical hub portion 406a in the center around which the magnetic tape MT1 is wound, an upper flange 406c having approximately the same size as the lower flange 406b, and a reel plate 411 sandwiched between the hub portion 406a and the upper flange 406c. The reel 407 has the same configuration as the reel 406.

[0130] The window member 423 is provided with mounting holes 423a at positions corresponding to the reels 406 and 407, respectively, for assembling reel holders 422, which are reel holding means for preventing these reels from floating up. The magnetic tape MT1 is the same as the magnetic tape T in the first embodiment.

[0131] (4) Description of each layer of magnetic recording media

[0132] Next, the configuration of the magnetic recording medium 1 will be described with reference to the aforementioned Fig. 2. The magnetic recording medium 1 is, for example, a magnetic recording medium that has been subjected to a vertical orientation process, and as shown in Fig. 2, includes a long base layer (also referred to as substrate) 41, an underlayer (non-magnetic layer) 42 provided on one major surface of the base layer 41, a magnetic layer (also referred to as recording layer) 43 provided on the underlayer 42, and a back layer 44 provided on the other major surface of the base layer 41. Hereinafter, of the two major surfaces of the magnetic recording medium 1, the surface on which the magnetic layer 43 is provided will be referred to as the magnetic surface, and the surface opposite to the magnetic surface (the surface on which the back layer 44 is provided) will be referred to as the back surface.

[0133] The magnetic recording medium 1 has an elongated shape and runs in the longitudinal direction during recording and reproduction. The magnetic recording medium 1 may be configured to record signals at a shortest recording wavelength of preferably 100 nm or less, more preferably 75 nm or less, even more preferably 60 nm or less, and particularly preferably 50 nm or less, and may be used, for example, in a recording and reproduction device whose shortest recording wavelength is within the above range. This recording and reproduction device may be equipped with a ring-type head as a recording head. The recording track width is, for example, 2 μm or less.

[0134] [Base layer]

[0135] The base layer 41 can function as a support for the magnetic recording medium 1 and can be, for example, a flexible, long, non-magnetic substrate, particularly a non-magnetic film. The thickness of the base layer 41 can be, for example, 2.0 μm to 5.0 μm, preferably 2.2 μm to 4.6 μm, more preferably 2.5 μm to 4.2 μm, and even more preferably 2.6 μm to 3.8 μm. The base layer 41 can contain, for example, at least one of polyester resins, polyolefin resins, cellulose derivatives, vinyl resins, aromatic polyether ketone resins, and other polymer resins. When the base layer 11 contains two or more of the above materials, the two or more materials can be mixed, copolymerized, or laminated.

[0136] The average thickness of the base layer 41 is determined as follows. First, the magnetic tape 1 housed in the magnetic recording cartridge 10 is unwound, and samples are prepared by cutting out pieces of 250 mm length from three positions: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from the joint between the magnetic tape 1 and the leader tape LT. In this specification, the "longitudinal direction" in the "longitudinal direction from the joint between the magnetic tape 1 and the leader tape LT" refers to the direction from one end on the leader tape LT side toward the other end on the opposite side.

[0137] Next, all layers other than the base layer 41 of each sample (i.e., the non-magnetic layer (underlayer) 42, the magnetic layer 43, and the back layer 44) are removed with acetone, ethanol, or the like. Next, using a Mitutoyo Laser Hologram (LGH-110C) as a measuring device, the thickness of the sample (base layer 41) is measured at five positions, and these measurements (15 positions in total) are simply averaged (arithmetic mean) to calculate the average thickness of the base layer 41. Note that the five measurement positions are selected randomly from each sample so that they are different positions in the longitudinal direction of the magnetic tape 1.

[0138] The polyester-based resin may be, for example, one or a mixture of two or more of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PCT (polycyclohexylene dimethylene terephthalate), PEB (polyethylene-p-oxybenzoate), and polyethylene bisphenoxycarboxylate. According to a preferred embodiment of the present technology, the base layer 41 may be formed from PET or PEN.

[0139] The polyolefin resin may be, for example, one or a mixture of two or more of PE (polyethylene) and PP (polypropylene).

[0140] The cellulose derivative may be, for example, one or a mixture of two or more of cellulose diacetate, cellulose triacetate, CAB (cellulose acetate butyrate), and CAP (cellulose acetate propionate).

[0141] The vinyl resin may be, for example, one or a mixture of two or more of PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride).

[0142] The aromatic polyetherketone resin may be, for example, one or a mixture of two or more of PEK (polyetherketone), PEEK (polyetheretherketone), PEKK (polyetherketoneketone), and PEEKK (polyetheretherketoneketone). According to a preferred embodiment of the present technology, the base layer 41 may be formed from PEEK.

[0143] The other polymer resin may be, for example, one or a mixture of two or more of PA (polyamide, nylon), aromatic PA (aromatic polyamide, aramid), PI (polyimide), aromatic PI (aromatic polyimide), PAI (polyamideimide), aromatic PAI (aromatic polyamideimide), PBO (polybenzoxazole, for example, Zylon (registered trademark)), polyether, polyetherester, PES (polyethersulfone), PEI (polyetherimide), PSF (polysulfone), PPS (polyphenylene sulfide), PC (polycarbonate), PAR (polyarylate), and PU (polyurethane).

[0144] [Magnetic layer]

[0145] The magnetic layer 43 may be, for example, a perpendicular recording layer. The magnetic layer 43 may contain magnetic powder. In addition to the magnetic powder, the magnetic layer 43 may further contain, for example, a binder and conductive particles. The magnetic layer 43 may further contain additives such as a lubricant, an abrasive, and an anti-rust agent, as necessary.

[0146] The average thickness t of the magnetic layer 43 m is preferably 35 nm≦t m ≦120 nm, and more preferably 35 nm≦t m ≦100 nm, and particularly preferably 35 nm≦t m The average thickness t of the magnetic layer 43 can be ≦90 nm. m Being within the above range contributes to improving the electromagnetic conversion characteristics.

[0147] The average thickness t of the magnetic layer 43 mis determined as follows. First, the magnetic tape 1 housed in the magnetic recording cartridge 10 is unwound, and samples are cut to lengths of 250 mm from three locations: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from the connection between the magnetic tape 1 and the leader tape LT. Next, each sample is thinned using a FIB method or similar. When using the FIB method, a carbon layer and a tungsten layer are formed as protective films as a pretreatment for observing the cross-sectional TEM images described below. The carbon layer is formed by vapor deposition on the surface of the magnetic tape 1 facing the magnetic layer 43 and the surface facing the back layer 44, and the tungsten layer is further formed by vapor deposition or sputtering on the surface facing the magnetic layer 43. The thinning is performed along the longitudinal direction of the magnetic tape 1. That is, the thinning results in a cross section parallel to both the longitudinal and thickness directions of the magnetic tape 1.

[0148] The cross section of each obtained sliced ​​sample is observed under a transmission electron microscope (TEM) under the following conditions to obtain a TEM image of each sliced ​​sample. Note that the magnification and acceleration voltage may be adjusted appropriately depending on the type of device. Apparatus: TEM (Hitachi H9000NAR) Accelerating voltage: 300 kV Magnification: 100,000x

[0149] Next, using the TEM image of each obtained sliced ​​sample, the thickness of the magnetic layer 43 is measured at five positions on each sliced ​​sample. The five measurement positions on each sliced ​​sample are randomly selected from the sample so that they are different positions in the longitudinal direction of the magnetic tape 1. The measured values ​​of each obtained sliced ​​sample (a total of 15 thicknesses of the magnetic layer 43) are simply averaged (arithmetic average) to obtain the average value, which is defined as the average thickness tm [nm] of the magnetic layer 43.

[0150] The magnetic layer 43 is preferably a magnetic layer that is perpendicularly oriented. In this specification, perpendicular orientation means that the squareness ratio S1 measured in the longitudinal direction (travel direction) of the magnetic recording medium 1 is 35% or less. The magnetic layer 43 may be an in-plane oriented (longitudinal oriented) magnetic layer. That is, the magnetic recording medium 1 may be a horizontal recording type magnetic recording medium. However, from the viewpoint of achieving high recording density, a perpendicular orientation is more preferable.

[0151] [Magnetic powder]

[0152] Examples of magnetic particles constituting the magnetic powder contained in the magnetic layer 43 include, but are not limited to, epsilon iron oxide (ε iron oxide), gamma hematite, magnetite, chromium dioxide, cobalt-coated iron oxide, hexagonal ferrite, barium ferrite (BaFe), Co ferrite, strontium ferrite, and metals. The magnetic powder may be one of these, or a combination of two or more. Particularly preferably, the magnetic powder may include ε iron oxide magnetic powder, barium ferrite magnetic powder, cobalt ferrite magnetic powder, or strontium ferrite magnetic powder. The ε iron oxide may contain Ga and / or Al. These magnetic particles may be appropriately selected by those skilled in the art based on factors such as the manufacturing method of the magnetic layer 43, the tape specifications, and the tape functions.

[0153] The average particle size (average maximum particle size) D of the magnetic powder can be preferably 22 nm or less, more preferably 8 nm or more and 22 nm or less, and even more preferably 10 nm or more and 20 nm or less.

[0154] The average particle size D of the magnetic powder is determined as follows. First, the magnetic recording medium 1 to be measured is processed by a FIB (Focused Ion Beam) method or the like to prepare a thin piece, and the cross section of the thin piece is observed by a TEM. Next, 500 ε-iron oxide particles are randomly selected from the TEM photograph, and the maximum particle size d of each particle is measured. max Measure the maximum particle size d of the magnetic powder.max The particle size distribution is calculated as follows: max " refers to the so-called maximum Feret diameter, specifically the maximum distance between two parallel lines drawn from any angle so as to be tangent to the contour of the ε-iron oxide particle. Then, the maximum particle size d max The maximum particle size d from the particle size distribution max The median diameter (50% diameter, D50) is determined and used as the average particle size (average maximum particle size) D of the magnetic powder.

[0155] The shape of the magnetic particles depends on the crystal structure of the magnetic particles. For example, BaFe and strontium ferrite can be hexagonal plate-shaped. ε-iron oxide can be spherical. Cobalt ferrite can be cubic. Metal can be spindle-shaped. These magnetic particles are oriented during the manufacturing process of the magnetic recording medium 1.

[0156] According to one preferred embodiment of the present technology, the magnetic powder may preferably comprise a powder of nanoparticles containing ε-iron oxide (hereinafter referred to as "ε-iron oxide particles"). ε-iron oxide particles can achieve high coercivity even when they are fine particles. It is preferable that the ε-iron oxide contained in the ε-iron oxide particles has a preferential crystal orientation in the thickness direction (perpendicular direction) of the magnetic recording medium 1.

[0157] The ε-iron oxide particles are spherical or nearly spherical, or cubic or nearly cubic. Because of the shape of the ε-iron oxide particles, when used as magnetic particles, the contact area between particles in the thickness direction of the medium can be reduced, and particle aggregation can be suppressed, compared to when hexagonal plate-shaped barium ferrite particles are used as magnetic particles. This improves the dispersibility of the magnetic powder, resulting in a better SNR (Signal-to-Noise Ratio).

[0158] The ε-iron oxide particles have a core-shell structure. Specifically, as shown in Fig. 21, the ε-iron oxide particles include a core 221 and a two-layer shell 222 provided around the core 221. The two-layer shell 222 includes a first shell 222a provided on the core 221 and a second shell 222b provided on the first shell 222a.

[0159] The core portion 221 contains ε-iron oxide. The ε-iron oxide contained in the core portion 221 preferably has ε-Fe2O3 crystals as its main phase, and more preferably is made of single-phase ε-Fe2O3.

[0160] The first shell portion 222a covers at least a portion of the periphery of the core portion 221. Specifically, the first shell portion 222a may cover a portion of the periphery of the core portion 221, or may cover the entire periphery of the core portion 221. From the viewpoint of ensuring sufficient exchange coupling between the core portion 221 and the first shell portion 222a and improving magnetic properties, it is preferable that the entire surface of the core portion 221 be covered.

[0161] The first shell portion 222a is a so-called soft magnetic layer and may include, for example, a soft magnetic material such as α-Fe, a Ni-Fe alloy, or an Fe-Si-Al alloy. The α-Fe may be obtained by reducing ε-iron oxide contained in the core portion 221.

[0162] The second shell portion 222b is an oxide coating that serves as an oxidation prevention layer. The second shell portion 222b may contain α-iron oxide, aluminum oxide, or silicon oxide. The α-iron oxide may include at least one iron oxide selected from Fe3O4, Fe2O3, and FeO. When the first shell portion 222a contains α-Fe (soft magnetic material), the α-iron oxide may be obtained by oxidizing the α-Fe contained in the first shell portion 222a.

[0163] The ε-iron oxide particles have the first shell portion 222a as described above, which ensures thermal stability, thereby maintaining a high coercivity Hc of the core portion 221 alone and / or adjusting the coercivity Hc of the ε-iron oxide particles (core-shell particles) as a whole to a coercivity Hc suitable for recording. Furthermore, the ε-iron oxide particles have the second shell portion 222b as described above, which prevents the ε-iron oxide particles from being exposed to air during and before the manufacturing process of the magnetic recording medium 1, which can lead to rust and other damage on the particle surface. This prevents the deterioration of the properties of the ε-iron oxide particles.

[0164] As shown in Fig. 22, the epsilon iron oxide particles may have a shell portion 223 with a single layer structure. In this case, the shell portion 223 has the same structure as the first shell portion 222a. However, from the viewpoint of suppressing deterioration of the properties of the epsilon iron oxide particles, it is more preferable that the epsilon iron oxide particles have a shell portion 222 with a two-layer structure.

[0165] The ε-iron oxide particles may contain an additive instead of a core-shell structure, or may have a core-shell structure and contain an additive. In these cases, a portion of the Fe in the ε-iron oxide particles is substituted with the additive. By including an additive in the ε-iron oxide particles, the coercivity Hc of the entire ε-iron oxide particles can be adjusted to a coercivity Hc suitable for recording, thereby improving ease of recording. The additive is a metal element other than iron, preferably a trivalent metal element, more preferably one or more selected from the group consisting of aluminum (Al), gallium (Ga), and indium (In). Specifically, the ε-iron oxide containing additives is ε-Fe 2-x M x O3 crystal (wherein M is a metal element other than iron, preferably a trivalent metal element, more preferably one or more selected from the group consisting of Al, Ga, and In. x is, for example, 0 <x<1である。)である。

[0166] According to another preferred embodiment of the present technology, the magnetic powder may be barium ferrite (BaFe) magnetic powder. The barium ferrite magnetic powder includes magnetic particles of iron oxide with barium ferrite as the main phase (hereinafter referred to as "barium ferrite particles"). The barium ferrite magnetic powder has high reliability in data recording, for example, because the coercive force does not decrease even in a high-temperature and high-humidity environment. From this perspective, the barium ferrite magnetic powder is preferable as the magnetic powder.

[0167] The average particle size of the barium ferrite magnetic powder is 50 nm or less, more preferably 10 nm or more and 40 nm or less, and even more preferably 12 nm or more and 25 nm or less.

[0168] When the magnetic layer 43 contains barium ferrite magnetic powder as the magnetic powder, the average thickness t m [nm] is 35nm≦t m Preferably, the coercive force Hc measured in the thickness direction (perpendicular direction) of the magnetic recording medium 1 is 160 kA / m or more and 280 kA / m or less, more preferably 165 kA / m or more and 275 kA / m or less, and even more preferably 170 kA / m or more and 270 kA / m or less.

[0169] According to yet another preferred embodiment of the present technology, the magnetic powder may be cobalt ferrite magnetic powder. The cobalt ferrite magnetic powder includes magnetic particles of iron oxide having cobalt ferrite as a main phase (hereinafter referred to as "cobalt ferrite magnetic particles"). The cobalt ferrite magnetic particles preferably have uniaxial anisotropy. The cobalt ferrite magnetic particles have, for example, a cubic or nearly cubic shape. The cobalt ferrite is cobalt ferrite containing Co. The cobalt ferrite may further include one or more elements selected from the group consisting of Ni, Mn, Al, Cu, and Zn in addition to Co.

[0170] Cobalt ferrite has an average composition represented by the following formula (1), for example. Co x M y FeO z···(1) (In formula (1), M is, for example, one or more metals selected from the group consisting of Ni, Mn, Al, Cu, and Zn. x is a value within the range of 0.4≦x≦1.0. y is a value within the range of 0≦y≦0.3, with the proviso that x and y satisfy the relationship (x+y)≦1.0. z is a value within the range of 3≦z≦4. A portion of Fe may be substituted with another metal element.)

[0171] The average particle size of the cobalt ferrite magnetic powder is preferably 25 nm or less, more preferably 23 nm or less.The coercive force Hc of the cobalt ferrite magnetic powder is preferably 2500 Oe or more, more preferably 2600 Oe to 3500 Oe.

[0172] According to yet another preferred embodiment of the present technology, the magnetic powder may include a powder of nanoparticles containing hexagonal ferrite (hereinafter referred to as "hexagonal ferrite particles"). The hexagonal ferrite particles have, for example, a hexagonal plate shape or an approximately hexagonal plate shape. The hexagonal ferrite may preferably contain at least one of Ba, Sr, Pb, and Ca, more preferably at least one of Ba and Sr. Specifically, the hexagonal ferrite may be, for example, barium ferrite or strontium ferrite. Barium ferrite may further contain at least one of Sr, Pb, and Ca in addition to Ba. Strontium ferrite may further contain at least one of Ba, Pb, and Ca in addition to Sr. More specifically, hexagonal ferrites have the general formula MFe 12 O 19 The alloy may have an average composition represented by the formula: where M is, for example, at least one metal selected from Ba, Sr, Pb, and Ca, preferably at least one metal selected from Ba and Sr. M may be a combination of Ba and one or more metals selected from the group consisting of Sr, Pb, and Ca. M may also be a combination of Sr and one or more metals selected from the group consisting of Ba, Pb, and Ca. In the above general formula, part of Fe may be substituted with another metal element. When the magnetic powder includes a powder of hexagonal ferrite particles, the average particle size of the magnetic powder is preferably 50 nm or less, more preferably 10 nm or more and 40 nm or less, and even more preferably 15 nm or more and 30 nm or less.

[0173] [Binder]

[0174] The binder is preferably a resin having a structure in which a crosslinking reaction has been imparted to a polyurethane resin or a vinyl chloride resin. However, the binder is not limited to these, and other resins may be appropriately blended depending on the physical properties required for the magnetic recording medium 1. The resin to be blended is not particularly limited, as long as it is a resin that is generally used in coating-type magnetic recording media.

[0175] Examples of the binder include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, acrylic acid ester-vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer, acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinyl chloride copolymer, methacrylic acid ester-ethylene copolymer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene-butadiene copolymer, polyester resin, amino resin, and synthetic rubber.

[0176] Furthermore, a thermosetting resin or a reactive resin may be used as the binder, and examples of such a resin include a phenolic resin, an epoxy resin, a urea resin, a melamine resin, an alkyd resin, a silicone resin, a polyamine resin, and a urea-formaldehyde resin.

[0177] Furthermore, to improve the dispersibility of the magnetic powder, polar functional groups such as -SO3M, -OSO3M, -COOM, and P=O(OM)2 may be introduced into each of the binders described above, where M is a hydrogen atom or an alkali metal such as lithium, potassium, or sodium.

[0178] Furthermore, the polar functional groups include -NR1R2 and -NR1R2R3 + X - Side chain type with terminal group of >NR1R2 + X - In the formula, R1, R2, and R3 are hydrogen atoms or hydrocarbon groups, and X - is a halogen ion such as fluorine, chlorine, bromine, or iodine, or an inorganic or organic ion. Polar functional groups include —OH, —SH, —CN, and epoxy groups.

[0179] [Additives]

[0180] The magnetic layer 43 may further contain non-magnetic reinforcing particles such as aluminum oxide (α, β, or γ alumina), chromium oxide, silicon oxide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, titanium oxide (rutile or anatase titanium oxide), etc.

[0181] [Nonmagnetic layer (base layer)]

[0182] The non-magnetic layer (underlayer) 42 is a non-magnetic layer containing non-magnetic powder and a binder as its main components. The above description of the binder contained in the magnetic layer 43 also applies to the binder contained in the non-magnetic layer (underlayer) 42. The non-magnetic layer (underlayer) 42 may further contain at least one additive selected from the group consisting of conductive particles, lubricants, hardeners, and rust inhibitors, as needed.

[0183] The average thickness of the nonmagnetic layer (underlayer) 42 is preferably 0.6 μm or more and 2.0 μm or less, more preferably 0.8 μm or more and 1.4 μm or less. The average thickness of the nonmagnetic layer (underlayer) 42 is determined as follows. First, the magnetic tape 1 housed in the magnetic recording cartridge 10 is unwound, and samples are cut into 250 mm lengths at three locations: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from the connection between the magnetic tape 1 and the leader tape LT. Next, each sample is processed into thin sections using a FIB method or the like. When using the FIB method, a carbon layer and a tungsten layer are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below. The carbon layer is formed by vapor deposition on the surface of the magnetic tape 1 facing the magnetic layer 43 and the surface facing the back layer 44, and the tungsten layer is further formed by vapor deposition or sputtering on the surface facing the magnetic layer 43. The thinning is performed along the longitudinal direction of the magnetic tape 1. That is, the thinning forms a cross section parallel to both the longitudinal direction and the thickness direction of the magnetic tape 1.

[0184] The cross section of each of the obtained thinned samples is observed under a transmission electron microscope (TEM) under the following conditions. Apparatus: TEM (Hitachi H9000NAR) Accelerating voltage: 300 kV Magnification: 100,000x Next, using the obtained TEM image, the thickness of the non-magnetic layer 42 is measured at at least 15 positions along the longitudinal direction of the magnetic tape 1, and then the measured values ​​are simply averaged (arithmetic averaged) to obtain the average thickness (μm) of the non-magnetic layer (underlayer) 42.

[0185] [Non-magnetic powder]

[0186] The non-magnetic powder contained in the underlayer 42 may include, for example, at least one type selected from inorganic particles and organic particles. One type of non-magnetic powder may be used alone, or two or more types of non-magnetic powder may be used in combination. The inorganic particles may include, for example, one or a combination of two or more types selected from metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, and metal sulfides. More specifically, the inorganic particles may be, for example, one or more types selected from iron oxyhydroxide, hematite, titanium oxide, and carbon black. The shape of the non-magnetic powder may be, for example, acicular, spherical, cubic, plate-like, or other shapes, but is not particularly limited to these.

[0187] [Back layer]

[0188] The back layer 44 may contain a binder and non-magnetic powder. The back layer 44 may also contain various additives such as a lubricant, a curing agent, and an antistatic agent as necessary. The above description of the binder and non-magnetic powder contained in the non-magnetic layer (underlayer) 42 also applies to the binder and non-magnetic powder contained in the back layer 44.

[0189] The average particle size of the inorganic particles contained in the back layer 44 is preferably 10 nm or more and 150 nm or less, and more preferably 15 nm or more and 110 nm or less. The average particle size of the inorganic particles is determined in the same manner as the average particle size D of the magnetic powder described above.

[0190] The average thickness t of the back layer 44 b is t b The average thickness t of the back layer 44 is preferably ≦0.6 μm. b When the average thickness t of the magnetic recording medium 1 is within the above range, T A T Even when set to ≦5.5 μm, the thicknesses of the nonmagnetic layer (underlayer) 42 and base layer 41 can be kept thick, thereby maintaining the running stability of the magnetic recording medium 1 within a recording / reproducing device.

[0191] The average thickness t of the back layer 44 bis calculated as follows: The magnetic tape 1 housed in the magnetic recording cartridge 10 is unwound, and samples are cut out to a length of 250 mm from each of three positions, 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from the connection between the magnetic tape 1 and the leader tape LT, to prepare samples. First, the average thickness (average total thickness) t of the magnetic tape 1 is measured using the measurement method described in the "Average Thickness of Magnetic Recording Medium" below. T Measure the average thickness t T After measuring the average total thickness, the back layer 44 of each sample whose average thickness was measured is removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Next, using a Mitutoyo Laser Hologram (LGH-110C), the thickness of the sample is measured at five positions, and these measurements (15 points in total) are simply averaged (arithmetic mean) to obtain the average value t B Then, the average thickness t of the back layer 44 is calculated using the following formula: b The five measurement positions are selected at random from each sample so that they are different positions in the longitudinal direction of the magnetic tape 1. t b [μm]=t T [μm]-t B [μm]

[0192] (5) Physical properties and structure of magnetic recording media

[0193] [Width change amount Δ of magnetic recording medium]

[0194] When the width change Δ is measured over the entire length of the magnetic recording medium after storage at 65°C for 360 hours, the sign of the width change Δout on the outside of the roll is different from the sign of the width change Δin on the inside of the roll. Because the sign of the width change Δout on the outside of the roll is different from the sign of the width change Δin on the inside of the roll, excellent running stability can be obtained even when stored in a high-temperature environment. Furthermore, when the entire length of the magnetic recording medium is divided into four equal parts, the width change Δ is 0 ppm at either of two positions on either side of the center line of the entire length of the magnetic recording medium. In this way, the width change Δ is 0 ppm in a specific region in the longitudinal direction of the magnetic recording medium, thereby achieving excellent running stability even when stored in a high-temperature environment.

[0195] The width change Δ of the magnetic recording medium is measured as follows.

[0196] First, the servo band pitch in the longitudinal direction of the magnetic recording medium in its initial state before storage for 360 hours at 65° C. is measured using the magnetic recording and reproducing device 30. The servo band pitch means the interval between the arrangement of the servo bands. In measuring the servo band pitch, the magnetic tape 1 is wound into the magnetic recording cartridge 10 with a tension of 0.55 N, and the magnetic tape 1 housed in the magnetic recording cartridge 10 is run so as to be wound into the magnetic recording and reproducing device 30 (running in the so-called forward direction) in an environment of 32°C and 55% RH, and the servo band pitch is measured at each position in the longitudinal direction of the magnetic tape 1 over the entire length of the magnetic tape 1. In this measurement, the tension applied to the magnetic tape 1 is 0.55 N, and the running speed is 3 to 6 m / s. Next, the magnetic tape 1 is wound into the magnetic recording cartridge 10 with a tension of 0.55 N and stored at 65°C and 40 RH% for 24 hours, then run once back and forth at a tension of 0.55 N in a magnetic recording and reproducing device in an environment of 32°C and 55 RH%, and then stored again in an environment of 65°C and 40 RH% for 24 hours, after which it is run once back and forth at a tension of 0.55 N in a magnetic recording and reproducing device in an environment of 32°C and 55 RH%, repeating this process for a total of 360 hours of storage. The ratio of the servo band pitch after storage at each position in the longitudinal direction of the magnetic tape 1 to the servo band pitch at the corresponding position in the longitudinal direction in the initial state (corresponding positions in the longitudinal direction mean positions with the same length ratio in the entire length) is defined as the width change amount Δ. The part where the width change amount Δ is minimum and the part where the width change amount Δ is maximum are identified, and the maximum width change amount Δ is calculated. max and the minimum width change Δ min Find the difference between The method for measuring the servo band pitch will be described in more detail below. Here, an example will be described in which the drive head 36 tracks the data band d0 sandwiched between the servo band s2 and the servo band s3, as shown in FIG.

[0197] As described above, the method for measuring the servo band pitch using the magnetic recording and reproducing device 30 involves running the magnetic tape 1 over its entire length using the magnetic recording and reproducing device 30, measuring the numerical values ​​representing the relative positions of the servo trace lines T on each servo band of the two servo read heads 132 with respect to the servo pattern 6, and calculating the servo band pitch from the measured relative positions of each servo trace line T with respect to the servo pattern 6. The spacing between the servo trace lines T shown by the solid line in Fig. 19 indicates the servo band pitch when the width of the magnetic tape 1 does not change (first pitch P1, which is the arrangement distance between the two servo read heads 132 of the drive head 36). Also, the spacing between the servo trace lines T shown by the dashed line in Fig. 19 corresponds to the servo band pitch (P2') when the width of the magnetic tape 1 is expanded.

[0198] 20 is a diagram illustrating a method for measuring the servo trace line T. The magnetic recording and reproducing device 30 outputs a servo reproduction signal having a waveform corresponding to the position of the servo trace line T relative to the servo pattern 6. Typically, the distance AC between the A burst and the C burst, which are arrays of inclined patterns of the same shape, and the distance AB between the A burst and the B burst, which are arrays of inclined patterns of different shapes, are calculated, and a numerical value representing the relative position of the servo trace line T of each servo read head 132 relative to the servo pattern 6 is calculated using the following formula (1). Note that θ is the azimuth angle of each inclined pattern, which corresponds to the angle α in FIG. 5, and is set to 12° in this example. The distance AC is calculated by multiplying AC Time by the tape running speed. Here, AC Time means the time from signal A to signal C. When measuring AC Time using multiple servo frames, the distance AC is calculated by multiplying the arithmetic mean value of AC Time by the tape running speed. Similarly, the distance AB is calculated by multiplying AB Time by the tape running speed. Here, AB Time refers to the time from signal A to signal B. In the following [Equation 1], ΣAB Time and ΣAC Time refer to the integrated values ​​of AB Time and AC Time for 100 to 100,000 servo frames. In [Equation 1], when calculating (ΣAB Time / ΣAC Time), if AB Time is the time when the servo playback waveform between the first slope portions has a peak, AC Time is also the time when the servo playback waveform between the first slope portions has a peak. If AB Time is the time when the servo playback waveform between the second slope portions has a peak, AC Time is also the time when the servo playback waveform between the second slope portions has a peak. If AB Time is the time when the servo playback waveform between the third slope portions has a peak, AC Time is also the time when the servo playback waveform between the third slope portions has a peak. If AB Time is the time when the servo playback waveform between the fourth slope portions has a peak, AC Time is also the time when the servo playback waveform between the fourth slope portions has a peak. The position of T is the position where (ΣAB Time / ΣAC Time) is 1.

[0199]

number

[0200] Here, the distance AC may be the distance AC1 between the first slopes of the A burst and the C burst, the distance AC2 between their second slopes, the distance AC3 between their third slopes, or the distance AC4 between their fourth slopes. These distances AC (AC1 to AC4) are calculated by multiplying the tape running speed by the time between the timings at which the amplitude of the servo playback waveform reaches its maximum positive value (upper peak).

[0201] The servo band pitch is then calculated from the difference between the numerical value representing the position of the servo trace line T on the servo pattern in servo band s2, which is calculated from the ratio of distances AB and AC using equation [1], and the numerical value representing the position of the servo trace line T on the servo pattern in servo band s3. Here, of the two servo bands being measured, the difference is taken between the measurement value of the servo band on the tape edge side (servo band s3) and the measurement value of the servo band on the tape center side (servo band s2). The positive or negative value indicates the direction of change in tape width; a positive value corresponds to a narrowing of the servo band pitch, and a negative value corresponds to a widening of the servo band pitch. A difference of zero indicates no change in tape width.

[0202] The servo band pitch is preferably determined from measurements using a large number of servo frames, and may be, for example, a simple average value of measurements calculated from the differences between 100 to 100,000 servo frames. The number of measurements may be a simple average value within the above range. The tape tension during measurement is 0.55 N, and measurements are performed at a constant tension over the entire length of the magnetic tape 1.

[0203] As shown in FIG. 19, when the servo trace line T is at the position indicated by the dashed line, the distance AB is 38.5 μm and the distance AC is 76 μm in the servo band s2, and the distance AB is 37.5 μm and the distance AC is 76 μm in the servo band s3. In servo band s2, (38.5 / 76)×(76 / 2tan12°)=90.5641[μm] In servo band s3, (37.5 / 76)×(76 / 2tan12°)=88.2118[μm] The difference between these values ​​is 88.2118-90.5641=-2.3523[μm] This becomes: Therefore, the servo band pitch in this case is determined to be a value that is 2.3523 μm wider than the first pitch P1, which is the interval between the servo read heads.

[0204] 19, when the servo trace line T is located at the position indicated by the solid line, the distance AB is 38 μm and the distance AC is 76 μm for both the servo band s2 and the servo band s3. In this case, the servo band pitch is 89.3880 μm for both the servo band s2 and the servo band s3, and the difference therebetween is 0 μm.

[0205] The amount of width change in the longitudinal direction of the magnetic recording medium can be adjusted, for example, as follows. To reduce distortion and creep that occurs in the magnetic recording medium 1, the material of the base layer, its longitudinal and transverse strength (longitudinal and transverse stretching conditions), the type of magnetic layer (coated magnetic layer, vacuum thin-film magnetic layer), and, in the case of a coated layer, the Tg of the binder and the amount of hardener, etc., may be selected appropriately. Furthermore, to alleviate distortion, the magnetic recording medium 1 may be stored for a long period of time at a temperature of 65°C or higher before cutting, and further may be stored for a long period of time at a temperature of 55°C or higher before servo writing.

[0206] [Loss modulus, storage modulus]

[0207] The loss modulus of base layer 41 at 65° C. can be 0.40 GPa or less, preferably 0.35 GPa or less, more preferably 0.30 GPa or less, even more preferably 0.25 GPa or less, and preferably 0.20 GPa or less. By having the loss modulus within this range, it is possible to provide a magnetic recording cartridge that allows the width of the magnetic recording medium in the longitudinal direction to be adjusted by adjusting the running tension of the tape system or changing the winding direction, even when stored in a high-temperature environment of 60° C. or higher.

[0208] The loss modulus and storage modulus are measured by dynamic viscoelasticity measurement, which is a temperature-dependent measurement, and is specifically carried out as follows. The magnetic tape 1 housed in the magnetic recording cartridge 10 is unwound and cut into 250 mm lengths from three locations: 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from the connection between the magnetic tape 1 and the leader tape LT. All layers of the sample other than the base layer 41 (i.e., the nonmagnetic layer (underlayer) 42, the magnetic layer 43, and the back layer 44) are removed using acetone or ethanol. Both longitudinal ends of the sample are clamped to the measuring section of a dynamic viscoelasticity measuring device (RSA II, manufactured by TA Instruments). Dynamic viscoelasticity measurements are then performed under the following measurement conditions. Measurements are taken at five locations for each acid sample, and the measured values ​​(15 in total) are simply averaged (arithmetic mean) to calculate the loss modulus and storage modulus. The five measurement locations are randomly selected from each sample so that they are different positions along the longitudinal direction of the magnetic tape 1. Measurement temperature range: -10℃~180℃ Heating rate: 2°C / min Amplitude: Stretched and contracted with an amplitude of 0.1% of the initial tape length Measurement frequency: 10Hz Test Type: “Strain-Controlled” Measurement Type: "Dynamic" Environment in which the device is placed: Temperature 25°C, humidity 50%RH Humidity control of the measurement section: None Measurement N number: 3 More detailed settings regarding the measurement conditions of the device are as follows. That is, as described below, in the measurement, the tension is adjusted so that it does not become 0 or less, and the strain is adjusted so that it does not fall below the lower limit of the transducer. The measurement conditions for these adjustments may be appropriately set by those skilled in the art, but for example, the following settings may be adopted for the dynamic viscoelasticity measuring device. Option settings Delay Before Test: OFF Auto Tension (setting to adjust tension so that it never falls below 0) Mode Static Force Tracking Dynamic Force Auto Tension Direction Tension Initial Static Force 10.0g Static>Dynamic Force by 5.0% Minimum Static Force 1.0g Auto Tension Sensitivity 1.0g Auto Strain (setting to adjust strain so that it does not fall below the lower limit of the transducer) Max Applied Strain 0.1% Maximum Allowed Force 100.0g Min allowed force 2.0g Strain Adjustment 3.0% Meas Ops: Default setting

[0209] By carrying out the dynamic viscoelasticity measurement described above on the base layer 41, the values ​​of the loss modulus and storage modulus at a measurement temperature of 65°C can be obtained.

[0210] The loss modulus and storage modulus of the base layer 41 can be adjusted, for example, by the type of material forming the base layer, the stretching state of the base layer in the longitudinal and transverse directions, and / or the coating and drying process, calendaring process, curing process, aging process, etc.

[0211] For example, by using PEN, PET, or PEEK as the material for forming the base layer, the loss modulus and storage modulus can be made smaller than those of other materials.

[0212] [Arithmetic mean roughness Ra]

[0213] The arithmetic mean roughness Ra of the magnetic surface is preferably 2.5 nm or less, and more preferably 2.0 nm or less. When Ra is 2.5 nm or less, a better SNR can be obtained.

[0214] The arithmetic mean roughness Ra is determined as follows: First, an AFM (Atomic Force Microscope) (Dimension Icon, manufactured by Bruker) is used to observe the surface on which the magnetic layer 43 is provided, and a cross-sectional profile is obtained. Next, the arithmetic mean roughness Ra is determined from the obtained cross-sectional profile in accordance with JIS B0601:2001.

[0215] [Average thickness of magnetic recording medium t T ]

[0216] Average thickness t of magnetic recording medium 1 T The average thickness t of the magnetic recording medium 1 is preferably 5.6 μm or less, more preferably 5.4 μm or less, even more preferably 5.0 μm or less, and particularly preferably 4.6 μm or less. T t T When the average thickness t of the magnetic recording medium 1 is ≦5.6 μm, the recording capacity that can be recorded in one data cartridge can be increased compared to the conventional case. T The lower limit of t is not particularly limited, but for example, 3.5 μm≦t T is.

[0217] Average thickness t of magnetic recording medium 1 T is obtained as follows. First, the magnetic tape 1 housed in the magnetic recording cartridge 10 is unwound, and samples are cut out to a length of 250 mm from each of three positions, 10 m to 20 m, 30 m to 40 m, and 50 m to 60 m from the connection between the magnetic tape 1 and the leader tape LT, to prepare samples. Next, the thickness of each sample is measured at five positions using a Mitutoyo Laser Hologram (LGH-110C) as a measuring device, and these measurements (15 points in total) are simply averaged (arithmetic mean) to obtain the average thickness t T The five measurement positions are selected at random from each sample so that they are different positions in the longitudinal direction of the magnetic tape 1.

[0218] (6) Manufacturing method of magnetic recording medium

[0219] Next, a method for manufacturing the magnetic recording medium 1 having the above-described configuration will be described. First, a paint for forming an underlayer is prepared by kneading and / or dispersing non-magnetic powder, a binder, etc. in a solvent. Next, a paint for forming a magnetic layer is prepared by kneading and / or dispersing magnetic powder, a binder, etc. in a solvent. The following solvents, dispersing devices, and kneading devices can be used, for example, to prepare the paint for forming the magnetic layer and the paint for forming the underlayer.

[0220] Examples of solvents that can be used in preparing the coating material include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol-based solvents such as methanol, ethanol, and propanol; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, and ethylene glycol acetate; ether-based solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, and dioxane; aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene; and halogenated hydrocarbon-based solvents such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, and chlorobenzene. One of these solvents may be used, or a mixture of two or more of them may be used.

[0221] Examples of kneading devices that can be used in preparing the above-mentioned coating materials include, but are not limited to, continuous twin-screw kneaders, continuous twin-screw kneaders capable of multi-stage dilution, kneaders, pressure kneaders, and roll kneaders. Examples of dispersing devices that can be used in preparing the above-mentioned coating materials include, but are not limited to, roll mills, ball mills, horizontal sand mills, vertical sand mills, spike mills, pin mills, tower mills, pearl mills (such as the "DCP Mill" manufactured by Eirich), homogenizers, and ultrasonic dispersers.

[0222] Next, a non-magnetic layer (hereinafter also referred to as an underlayer) 42 is formed by applying a paint for forming an underlayer to one main surface of the base layer 41 and drying it. Subsequently, a paint for forming a magnetic layer is applied to the underlayer 42 and dried, thereby forming a magnetic layer 43 on the underlayer 42. During drying, the magnetic powder is magnetically oriented in the thickness direction of the base layer 41, for example, by a solenoid coil. Alternatively, during drying, the magnetic powder may be magnetically oriented in the longitudinal direction (running direction) of the base layer 41, for example, by a solenoid coil, and then magnetically oriented in the thickness direction of the base layer 41. After the magnetic layer 43 is formed, a back layer 44 is formed on the other main surface of the base layer 41. This completes the magnetic recording medium 1.

[0223] The obtained magnetic recording medium 1 is then rewound around a large diameter core and hardened. Finally, the magnetic recording medium 1 is calendered and then cut to a predetermined width (for example, 1 / 2 inch width). In this way, the desired long, thin magnetic recording medium 1 is obtained.

[0224] (7) Effects

[0225] A magnetic recording cartridge 10 according to a first embodiment includes a magnetic recording medium having a base layer and a reel, the base layer having a loss modulus of 0.40 GPa or less at 65°C, the magnetic recording medium is accommodated in a wound state on the reel, and when the width change of the magnetic recording medium is measured over its entire length after storage at 65°C for 360 hours, the sign of the width change Δout on the outside of the reel is different from the sign of the width change Δin on the inside of the reel, and the width change is 0 ppm at either of two portions on either side of the center line of the entire length of the magnetic recording medium when the entire length of the magnetic recording medium is divided into four equal parts. This makes it possible to provide a magnetic recording cartridge that allows the width of the magnetic recording medium in the longitudinal direction to be adjusted by adjusting the running tension of the tape system or changing the winding direction, even when stored in a high-temperature environment of 60°C or higher.

[0226] (8) Variations

[0227] [Variation 1]

[0228] The magnetic recording medium 1 may be incorporated into a library device. That is, the present technology also provides a library device equipped with at least one magnetic recording medium 1. The library device has a configuration capable of adjusting the tension applied to the magnetic recording medium 1 in the longitudinal direction, and may be equipped with a plurality of the above-described recording / reproducing devices 30.

[0229] [Variation 2]

[0230] The magnetic recording medium 1 may be subjected to a servo signal writing process by a servo writer. The servo writer can keep the width of the magnetic recording medium 1 constant or approximately constant by adjusting the tension in the longitudinal direction of the magnetic recording medium 1 when recording the servo signal. In this case, the servo writer can include a detection device that detects the width of the magnetic recording medium 1. The servo writer can adjust the tension in the longitudinal direction of the magnetic recording medium 1 based on the detection result of the detection device.

[0231] 3. Second embodiment (example of magnetic recording cartridge including vacuum thin film magnetic recording medium)

[0232] (1) Structure of magnetic recording cartridge

[0233] The magnetic recording cartridge of this embodiment is the same as the magnetic recording cartridge 1 described in "(1) Configuration of the Magnetic Cartridge" above in 2., except that it includes a vacuum thin-film magnetic recording medium 810 instead of the coating-type magnetic recording medium 1. The vacuum thin-film magnetic recording medium 810 will be described below.

[0234] 23, the magnetic recording medium 810 is a long perpendicular magnetic recording medium and includes a film-like base layer 811, a soft magnetic underlayer (hereinafter referred to as "SUL") 812, a first seed layer 813A, a second seed layer 813B, a first underlayer 814A, a second underlayer 814B, and a magnetic layer 815. The SUL 812, the first and second seed layers 813A and 813B, the first and second underlayers 814A and 814B, and the magnetic layer 815 may be vacuum thin films such as layers formed by sputtering (hereinafter also referred to as "sputtered layers").

[0235] The SUL 812, the first and second seed layers 813A, 813B, and the first and second underlayers 814A, 814B are provided between one major surface (hereinafter referred to as the "surface") of the base layer 811 and the magnetic layer 815, and are stacked in the order of SUL 812, first seed layer 813A, second seed layer 813B, first underlayer 814A, and second underlayer 814B from the base layer 811 toward the magnetic layer 815.

[0236] If necessary, the magnetic recording medium 810 may further include a protective layer 816 provided on the magnetic layer 815 and a lubricating layer 817 provided on the protective layer 816. Furthermore, if necessary, the magnetic recording medium 810 may further include a back layer 818 provided on the other main surface (hereinafter referred to as the "back surface") of the base layer 811.

[0237] Hereinafter, the longitudinal direction of the magnetic recording medium 810 (the longitudinal direction of the base layer 811) is referred to as the machine direction (MD). Here, the machine direction refers to the direction of relative movement of the recording and reproducing head with respect to the magnetic recording medium 810, that is, the direction in which the magnetic recording medium 810 runs during recording and reproduction.

[0238] The magnetic recording medium 810 is suitable for use as a storage medium for data archives, a demand for which is expected to increase in the future. The magnetic recording medium 810 has an areal recording density of 50 Gb / in, which is 10 times or more that of current coated magnetic recording media for storage. 2 When a magnetic recording medium 810 having such an areal recording density is used to configure a data cartridge of a general linear recording system, a large capacity of 100 TB or more can be recorded per data cartridge.

[0239] The magnetic recording medium 810 is suitable for use in a recording and reproducing device (a recording and reproducing device for recording and reproducing data) having a ring-type recording head and a giant magnetoresistive (GMR) or tunneling magnetoresistive (TMR) type reproducing head. The magnetic recording medium 810 according to the second embodiment preferably uses a ring-type recording head as a servo signal write head. A data signal is perpendicularly recorded on the magnetic layer 815, for example, by a ring-type recording head. A servo signal is perpendicularly recorded on the magnetic layer 815, for example, by a ring-type recording head.

[0240] (2) Description of each layer of magnetic recording media

[0241] (base layer)

[0242] The description of the base layer 811 for the base layer 41 in the first embodiment applies, so a description of the base layer 811 will be omitted. The average thickness, loss modulus, and storage modulus of the base layer 811 are measured in the same manner as for the base layer 41 in the first embodiment, except that the layers other than the base layer of each sample are removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid, and then washed with pure water.

[0243] (SUL)

[0244] SUL812 includes a soft magnetic material in an amorphous state. The soft magnetic material includes, for example, at least one of a Co-based material and an Fe-based material. The Co-based material includes, for example, CoZrNb, CoZrTa, or CoZrTaNb. The Fe-based material includes, for example, FeCoB, FeCoZr, or FeCoTa.

[0245] The SUL 812 is a single layer SUL, and is provided directly on the base layer 811. The average thickness of the SUL 812 is preferably 10 nm or more and 50 nm or less, and more preferably 20 nm or more and 30 nm or less.

[0246] The average thickness of the SUL 812 is determined by the same method as that used to measure the average thickness of the magnetic layer 43 in the first embodiment. The average thicknesses of the layers other than the SUL 812 (i.e., the average thicknesses of the first and second seed layers 813A and 813B, the first and second underlayers 814A and 814B, and the magnetic layer 815), which will be described later, are also determined by the same method as that used to measure the average thickness of the magnetic layer 43 in the first embodiment. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of each layer.

[0247] (First and second seed layers)

[0248] First seed layer 813A includes an alloy containing Ti and Cr, and is in an amorphous state. This alloy may further include O (oxygen). This oxygen may be impurity oxygen contained in trace amounts in first seed layer 813A when first seed layer 813A is formed by a film formation method such as sputtering.

[0249] Here, "alloy" refers to at least one of a solid solution, a eutectic, an intermetallic compound, etc. containing Ti and Cr. "Amorphous state" refers to a state in which a halo is observed by X-ray diffraction or electron diffraction, etc., and the crystal structure cannot be identified.

[0250] The atomic ratio of Ti to the total amount of Ti and Cr contained in first seed layer 813A is preferably within a range of 30 atomic % or more and less than 100 atomic %, more preferably 50 atomic % or more and less than 100 atomic %. If the atomic ratio of Ti is less than 30%, the (100) plane of the body-centered cubic lattice (bcc) structure of Cr will become oriented, and there is a risk that the orientation of first and second underlayers 814A and 814B formed on first seed layer 813A will be reduced.

[0251] The atomic ratio of Ti is determined as follows. While ion milling the magnetic recording medium 810 from the magnetic layer 815 side, a depth profile analysis (depth profile measurement) of the first seed layer 813A is performed by Auger Electron Spectroscopy (hereinafter referred to as "AES"). Next, the average composition (average atomic ratio) of Ti and Cr in the film thickness direction is determined from the obtained depth profile. Next, the atomic ratio of Ti is determined using the determined average composition of Ti and Cr.

[0252] When first seed layer 813A contains Ti, Cr, and O, the atomic ratio of O to the total amount of Ti, Cr, and O contained in first seed layer 813A is preferably 15 atomic % or less, more preferably 10 atomic % or less. If the atomic ratio of O exceeds 15 atomic %, TiO crystals are generated, which may affect the crystal nucleation of first and second underlayers 814A and 814B formed on first seed layer 813A, and may reduce the orientation of first and second underlayers 814A and 814B. The atomic ratio of O is determined using the same analytical method as for the atomic ratio of Ti.

[0253] The alloy contained in first seed layer 813A may further contain an element other than Ti and Cr as an additional element, which may be, for example, one or more elements selected from the group consisting of Nb, Ni, Mo, Al, and W.

[0254] The average thickness of first seed layer 813A is preferably 2 nm or more and 15 nm or less, and more preferably 3 nm or more and 10 nm or less.

[0255] The second seed layer 813B contains, for example, NiW or Ta, and is in a crystalline state. The average thickness of the second seed layer 813B is preferably 3 nm or more and 20 nm or less, and more preferably 5 nm or more and 15 nm or less.

[0256] The first and second seed layers 813A and 813B have a crystalline structure similar to that of the first and second base layers 814A and 814B, and are not seed layers provided for the purpose of crystal growth, but rather seed layers that improve the vertical orientation of the first and second base layers 814A and 814B due to the amorphous state of the first and second seed layers 813A and 813B.

[0257] (First and second base layers)

[0258] The first and second underlayers 814A and 814B preferably have the same crystal structure as the magnetic layer 815. When the magnetic layer 815 contains a Co-based alloy, the first and second underlayers 814A and 814B preferably contain a material with a hexagonal close-packed (hcp) structure similar to that of the Co-based alloy, with the c-axis of the structure oriented perpendicular to the film surface (i.e., in the film thickness direction). This enhances the orientation of the magnetic layer 815 and can achieve relatively good lattice constant matching between the second underlayer 814B and the magnetic layer 815. As the material with the hexagonal close-packed (hcp) structure, a material containing Ru is preferably used, specifically Ru alone or a Ru alloy. Examples of Ru alloys include Ru alloy oxides such as Ru-SiO2, Ru-TiO2, and Ru-ZrO2, and the Ru alloy may be any one of these.

[0259] As described above, the first and second underlayers 814A and 814B can be made of the same material. However, the first and second underlayers 814A and 814B have different intended effects. Specifically, the second underlayer 814B has a film structure that promotes the granular structure of the magnetic layer 815 that is the layer thereover, while the first underlayer 814A has a film structure that has a high degree of crystalline orientation. To achieve such film structures, it is preferable to use different film formation conditions, such as sputtering conditions, for the first and second underlayers 814A and 814B.

[0260] The average thickness of the first underlayer 814A is preferably 3 nm to 15 nm, more preferably 5 nm to 10 nm. The average thickness of the second underlayer 814B is preferably 7 nm to 40 nm, more preferably 10 nm to 25 nm.

[0261] (magnetic layer)

[0262] The magnetic layer (also referred to as the recording layer) 815 can be a perpendicular magnetic recording layer in which the magnetic material is perpendicularly oriented. From the viewpoint of improving recording density, the magnetic layer 815 is preferably a granular magnetic layer containing a Co-based alloy. This granular magnetic layer is composed of ferromagnetic crystal grains containing a Co-based alloy and nonmagnetic grain boundaries (nonmagnetic materials) surrounding the ferromagnetic crystal grains. More specifically, this granular magnetic layer is composed of columns (columnar crystals) containing a Co-based alloy and nonmagnetic grain boundaries (e.g., oxides such as SiO2) surrounding the columns and magnetically separating them. This structure allows the magnetic layer 815 to be constructed such that each column is magnetically separated.

[0263] The Co-based alloy has a hexagonal close-packed (hcp) structure, with its c-axis oriented perpendicular to the film surface (film thickness direction). The Co-based alloy is preferably a CoCrPt-based alloy containing at least Co, Cr, and Pt. The CoCrPt-based alloy may further contain an additive element. The additive element may be, for example, one or more elements selected from the group consisting of Ni, Ta, etc.

[0264] The nonmagnetic grain boundaries surrounding the ferromagnetic crystal grains contain a nonmagnetic metal material. Here, metal includes semimetal. Examples of the nonmagnetic metal material include at least one of a metal oxide and a metal nitride. From the viewpoint of maintaining a more stable granular structure, a metal oxide is preferable. Examples of metal oxides include metal oxides containing at least one element selected from the group consisting of Si, Cr, Co, Al, Ti, Ta, Zr, Ce, Y, and Hf. Metal oxides containing at least Si oxide (i.e., SiO2) are preferred. Specific examples of metal oxides include SiO2, Cr2O3, CoO, Al2O3, TiO2, Ta2O5, ZrO2, and HfO2. Examples of metal nitrides include metal nitrides containing at least one element selected from the group consisting of Si, Cr, Co, Al, Ti, Ta, Zr, Ce, Y, and Hf. Specific examples of metal nitrides include SiN, TiN, and AlN.

[0265] It is preferable that the CoCrPt alloy contained in the ferromagnetic crystal grains and the Si oxide contained in the non-magnetic grain boundaries have an average composition shown in the following formula (1). This is because it is possible to suppress the influence of the demagnetizing field and realize a saturation magnetization Ms that can ensure sufficient reproduction output, thereby achieving further improvement in the recording and reproduction characteristics. (Co x Pt y Cr 100-x-y ) 100-z -(SiO2) z ···(1) (In formula (1), x, y, and z are values ​​within the ranges of 69≦X≦75, 10≦y≦16, and 9≦Z≦12, respectively.)

[0266] The above composition can be determined as follows: While ion milling the magnetic recording medium 810 from the magnetic layer 815 side, depth direction analysis of the magnetic layer 815 is performed by AES to determine the average composition (average atomic ratio) of Co, Pt, Cr, Si, and O in the film thickness direction.

[0267] Average thickness t of the magnetic layer 815 m [nm] is preferably 9 nm ≦ t m ≦90 nm, more preferably 9 nm≦t m ≦20 nm, and even more preferably 9 nm≦t m The average thickness t of the magnetic layer 815 is ≦15 nm. m When the value of is within the above range, the electromagnetic conversion characteristics can be improved.

[0268] (protective layer)

[0269] The protective layer 816 includes, for example, a carbon material or silicon dioxide (SiO2), and preferably includes a carbon material from the viewpoint of the film strength of the protective layer 816. Examples of the carbon material include graphite, diamond-like carbon (DLC), and diamond.

[0270] (lubricating layer)

[0271] The lubricating layer 817 includes at least one type of lubricant. The lubricating layer 817 may further include various additives, such as a rust inhibitor, as necessary. The lubricant has at least two carboxyl groups and one ester bond and includes at least one type of carboxylic acid compound represented by the following general formula (1). The lubricant may further include a type of lubricant other than the carboxylic acid compound represented by the following general formula (1). General formula (1): [ka] (In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group or hydrocarbon group, Es is an ester bond, and R is, although it may be absent, an unsubstituted or substituted, saturated or unsaturated hydrocarbon group.)

[0272] The carboxylic acid compound is preferably one represented by the following general formula (2) or (3). General formula (2): [ka] (In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group or hydrocarbon group.) General formula (3): [ka] (In the formula, Rf is an unsubstituted or substituted, saturated or unsaturated fluorine-containing hydrocarbon group or hydrocarbon group.)

[0273] The lubricant preferably contains one or both of the carboxylic acid compounds represented by the above general formulas (2) and (3).

[0274] When a lubricant containing a carboxylic acid compound represented by general formula (1) is applied to magnetic layer 815 or protective layer 816, a lubricating effect is exhibited due to the cohesive force between the hydrophobic fluorine-containing hydrocarbon groups or hydrocarbon groups Rf. When the Rf group is a fluorine-containing hydrocarbon group, it preferably has a total of 6 to 50 carbon atoms and a total of 4 to 20 carbon atoms in the fluorinated hydrocarbon group. The Rf group may be, for example, a saturated or unsaturated linear, branched, or cyclic hydrocarbon group, but is preferably a saturated linear hydrocarbon group.

[0275] For example, when the Rf group is a hydrocarbon group, it is desirable that it is a group represented by the following general formula (4). General formula (4): [ka] (However, in general formula (4), l is an integer selected from the range of 8 to 30, more preferably 12 to 20.)

[0276] When the Rf group is a fluorine-containing hydrocarbon group, it is preferably a group represented by the following general formula (5). General formula (5): [ka] (In the general formula (5), m and n are integers independently selected from the following ranges: m=2 to 20, n=3 to 18, and more preferably m=4 to 13, n=3 to 10.)

[0277] The fluorohydrocarbon groups may be concentrated at one location within the molecule as described above, or may be dispersed as shown in the following general formula (6), and may be -CF3 or -CF2-, or may be -CHF2 or -CHF-, etc. General formula (6): [ka] (However, in general formulas (5) and (6), n1+n2=n, and m1+m2=m.)

[0278] The reason for limiting the number of carbon atoms in the general formulas (4), (5), and (6) as above is that if the number of carbon atoms constituting the alkyl group or fluorine-containing alkyl group (l or the sum of m and n) is equal to or greater than the lower limit, the length becomes appropriate, the cohesive force between the hydrophobic groups is effectively exerted, good lubricating action is exhibited, and friction and wear resistance are improved. On the other hand, if the number of carbon atoms is equal to or less than the upper limit, the solubility of the lubricant composed of the carboxylic acid compound in the solvent is maintained good.

[0279] In particular, when the Rf groups in the general formulae (1), (2), and (3) contain a fluorine atom, this is effective in reducing the coefficient of friction and further improving running performance, etc. However, it is preferable to provide a hydrocarbon group between the fluorine-containing hydrocarbon group and the ester bond to separate the fluorine-containing hydrocarbon group from the ester bond, thereby ensuring the stability of the ester bond and preventing hydrolysis.

[0280] The Rf group may also have a fluoroalkyl ether group or a perfluoropolyether group.

[0281] The R group in general formula (1) may not be present, but if present, it is preferably a hydrocarbon chain with a relatively small number of carbon atoms.

[0282] Furthermore, the Rf group or the R group contains one or more elements selected from nitrogen, oxygen, sulfur, phosphorus, and halogen as constituent elements, and may further have a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ester bond, or the like in addition to the functional groups described above.

[0283] Specifically, the carboxylic acid compound represented by general formula (1) is preferably at least one of the compounds shown below. That is, the lubricant preferably contains at least one of the compounds shown below. CF3(CF2)7(CH2) 10 COOCH(COOH)CH2COOH CF3(CF2)3(CH2) 10 COOCH(COOH)CH2COOH C 17 H 35 COOCH(COOH)CH2COOH CF3(CF2)7(CH2)2OCOCH2CH(C 18 H 37 )COOCH(COOH)CH2COOH CF3(CF2)7COOCH(COOH)CH2COOH CHF2(CF2)7COOCH(COOH)CH2COOH CF3(CF2)7(CH2)2OCOCH2CH(COOH)CH2COOH CF3(CF2)7(CH2)6OCOCH2CH(COOH)CH2COOH CF3(CF2)7(CH2) 11 OCOCH2CH(COOH)CH2COOH CF3(CF2)3(CH2)6OCOCH2CH(COOH)CH2COOH C 18 H 37 OCOCH2CH(COOH)CH2COOH CF3(CF2)7(CH2)4COOCH(COOH)CH2COOH CF3(CF2)3(CH2)4COOCH(COOH)CH2COOH CF3(CF2)3(CH2)7COOCH(COOH)CH2COOH CF3(CF2)9(CH2) 10 COOCH(COOH)CH2COOH CF3(CF2)7(CH2) 12 COOCH(COOH)CH2COOH CF3(CF2)5(CH2) 10 COOCH(COOH)CH2COOH CF3(CF2)7CH(C9H 19 )CH2CH=CH(CH2)7COOCH(COOH)CH2COOH CF3(CF2)7CH(C6H 13 )(CH2)7COOCH(COOH)CH2COOH CH3(CH2)3(CH2CH2CH(CH2CH2(CF2)9CF3))2(CH2)7COOCH(COOH)CH2COOH

[0284] The carboxylic acid compound represented by general formula (1) is soluble in non-fluorinated solvents that have a low environmental impact, and has the advantage that it can be applied by coating, immersion, spraying, etc. using general-purpose solvents such as hydrocarbon solvents, ketone solvents, alcohol solvents, and ester solvents. Specific examples of the general-purpose solvents include hexane, heptane, octane, decane, dodecane, benzene, toluene, xylene, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropanol, diethyl ether, tetrahydrofuran, dioxane, and cyclohexanone.

[0285] When the protective layer 816 contains a carbon material, applying the above-mentioned carboxylic acid compound as a lubricant onto the protective layer 816 causes two carboxyl groups and at least one ester bond group, which are the polar bases of the lubricant molecule, to be adsorbed onto the protective layer 816, and the cohesive force between the hydrophobic groups allows the formation of a particularly durable lubricant layer 817.

[0286] In addition, the lubricant may not only be retained as a lubricating layer 817 on the surface of the magnetic recording medium 810 as described above, but may also be contained and retained in layers such as the magnetic layer 815 and protective layer 816 that constitute the magnetic recording medium 810.

[0287] (Back layer)

[0288] The description of the back layer 44 in the first embodiment applies to the back layer 818 .

[0289] (3) Physical properties and structure of magnetic recording media

[0290] All of the explanations regarding the physical properties and structure described in 2.(5) above also apply to the second embodiment. Explanations regarding the physical properties and structure of the magnetic recording medium of the second embodiment will be omitted except for differences from the first embodiment. The average thickness, loss modulus, and storage modulus of the base layer 811 are measured in the same manner as for the base layer 41 in the first embodiment, except that layers other than the base layer of each sample are removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid, and then washed with pure water.

[0291] (4) Configuration of the sputtering equipment

[0292] 24, an example of the configuration of a sputtering apparatus 920 used in manufacturing magnetic recording medium 810 will be described. This sputtering apparatus 920 is a continuous winding type sputtering apparatus used to form SUL 812, first seed layer 813A, second seed layer 813B, first underlayer 814A, second underlayer 814B, and magnetic layer 815, and as shown in FIG. 24, includes a film formation chamber 921, a drum 922 which is a metal can (rotating body), cathodes 923a-923f, a supply reel 924, a take-up reel 925, and a plurality of guide rollers 927a-927c, 928a-928c. Sputtering apparatus 920 is, for example, a DC (direct current) magnetron sputtering type apparatus, but the sputtering type is not limited to this type.

[0293] The film formation chamber 921 is connected to a vacuum pump (not shown) via an exhaust port 926, and the atmosphere inside the film formation chamber 921 is set to a predetermined vacuum level by this vacuum pump. A rotatable drum 922, a supply reel 924, and a take-up reel 925 are arranged inside the film formation chamber 921. A plurality of guide rollers 927a to 927c are provided inside the film formation chamber 921 to guide the transport of the base layer 811 between the supply reel 924 and the drum 922, and a plurality of guide rollers 928a to 928c are provided inside the film formation chamber 921 to guide the transport of the base layer 811 between the drum 922 and the take-up reel 925. During sputtering, the base layer 811 unwound from the supply reel 924 is wound onto the take-up reel 925 via the guide rollers 927a to 927c, the drum 922, and the guide rollers 928a to 928c. The drum 922 has a cylindrical shape, and the long base layer 811 is transported along the cylindrical circumferential surface of the drum 922. The drum 922 is provided with a cooling mechanism (not shown), and is cooled to, for example, about −20° C. during sputtering. Inside the film formation chamber 921, multiple cathodes 923a to 923f are arranged facing the circumferential surface of the drum 922. Targets are set on each of these cathodes 923a to 923f. Specifically, targets for forming the SUL 812, the first seed layer 813A, the second seed layer 813B, the first underlayer 814A, the second underlayer 814B, and the magnetic layer 815 are set on the cathodes 923a, 923b, 923c, 923d, 923e, and 923f, respectively. These cathodes 923a to 923f simultaneously deposit multiple types of films, namely, SUL 812, first seed layer 813A, second seed layer 813B, first underlayer 814A, second underlayer 814B, and magnetic layer 815.

[0294] In the sputtering apparatus 920 having the above-described configuration, the SUL 812, the first seed layer 813A, the second seed layer 813B, the first underlayer 814A, the second underlayer 814B, and the magnetic layer 815 can be continuously deposited by the roll-to-roll method.

[0295] (5) Manufacturing method of magnetic recording medium

[0296] The magnetic recording medium 810 can be manufactured, for example, as follows.

[0297] First, using the sputtering apparatus 920 shown in FIG. 24, the SUL 812, first seed layer 813A, second seed layer 813B, first underlayer 814A, second underlayer 814B, and magnetic layer 815 are sequentially deposited on the surface of the base layer 811. Specifically, the deposition is performed as follows. First, the deposition chamber 921 is evacuated to a predetermined pressure. Then, while a process gas such as Ar gas is introduced into the deposition chamber 921, the targets set on the cathodes 923a to 923f are sputtered. As a result, the SUL 812, first seed layer 813A, second seed layer 813B, first underlayer 814A, second underlayer 814B, and magnetic layer 815 are sequentially deposited on the surface of the traveling base layer 811.

[0298] The atmosphere in the film forming chamber 921 during sputtering is, for example, 1×10 -5 Pa~5×10 -5 The pressure is set to about Pa. The film thickness and characteristics of SUL 812, first seed layer 813A, second seed layer 813B, first underlayer 814A, second underlayer 814B, and magnetic layer 815 can be controlled by adjusting the tape line speed for winding up base layer 811, the pressure of process gas such as Ar gas introduced during sputtering (sputtering gas pressure), input power, etc.

[0299] Next, protective layer 816 is formed on magnetic layer 815. Protective layer 816 can be formed by, for example, chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0300] Next, a paint for forming the back layer is prepared by kneading and dispersing a binder, inorganic particles, a lubricant, etc. in a solvent. Next, the paint for forming the back layer is applied to the back surface of the base layer 811 and dried, thereby forming the back layer 818 on the back surface of the base layer 811.

[0301] Next, for example, a lubricant is applied onto protective layer 816 to form lubricating layer 817. As a method for applying the lubricant, various application methods such as gravure coating and dip coating can be used. Next, if necessary, magnetic recording medium 810 is cut to a predetermined width. In this manner, magnetic recording medium 810 shown in FIG. 23 is obtained.

[0302] (6) Effects

[0303] Like the first embodiment, the magnetic recording cartridge according to the second embodiment has a high recording capacity per cartridge, and even when stored in a high-temperature environment of 60°C or higher, the longitudinal width of the magnetic recording medium 810 can be adjusted by adjusting the running tension of the tape system or changing the winding direction.

[0304] (7) Variations

[0305] The magnetic recording medium 810 may further include an underlayer between the base layer 811 and the SUL 812. Because the SUL 812 is amorphous, it does not promote epitaxial growth of layers formed on the SUL 812. However, it is required not to disturb the crystalline orientation of the first and second underlayers 814A and 814B formed on the SUL 812. To achieve this, it is preferable that the soft magnetic material have a fine structure that does not form columns. However, if the release of gases such as moisture from the base layer 811 has a significant effect, the soft magnetic material may become coarse and disturb the crystalline orientation of the first and second underlayers 814A and 814B formed on the SUL 812. To suppress the effect of the release of gases such as moisture from the base layer 811, it is preferable to provide an underlayer that contains an alloy containing Ti and Cr and has an amorphous state between the base layer 811 and the SUL 812, as described above. As a specific configuration of this underlayer, the same configuration as that of the first seed layer 813A of the second embodiment can be adopted.

[0306] The magnetic recording medium 810 does not necessarily have to include at least one of the second seed layer 813B and the second underlayer 814B. However, from the viewpoint of improving the SNR, it is more preferable to include both the second seed layer 813B and the second underlayer 814B.

[0307] The magnetic recording medium 810 may be provided with an APC-SUL (Antiparallel Coupled SUL) instead of a single-layer SUL.

[0308] (8) Other examples of magnetic recording media

[0309] (Configuration of another example of magnetic recording medium)

[0310] The magnetic recording cartridge 10 may include a magnetic recording medium 830, which will be described below, instead of the magnetic recording medium 810. As shown in Fig. 25, the magnetic recording medium 830 includes a base layer 811, an SUL 812, a seed layer 831, a first underlayer 832A, a second underlayer 832B, and a magnetic layer 815. In the description of the magnetic recording medium 830, the same components as those in the magnetic recording medium 810 are denoted by the same reference numerals, and the description thereof will be omitted.

[0311] The SUL 812, seed layer 831, first and second underlayers 832A and 832B are provided between one major surface of the base layer 811 and the magnetic layer 815, and are stacked in the order of SUL 812, seed layer 831, first underlayer 832A, and second underlayer 832B from the base layer 811 toward the magnetic layer 815.

[0312] (seed layer)

[0313] The seed layer 831 contains Cr, Ni, and Fe, and has a face-centered cubic lattice (fcc) structure, with the (111) plane of this face-centered cubic structure preferentially oriented so that it is parallel to the surface of the base layer 811. Here, preferred orientation means a state in which the diffraction peak intensity from the (111) plane of the face-centered cubic lattice structure is greater than the diffraction peaks from other crystal planes in a θ-2θ scan of an X-ray diffraction method, or a state in which only the diffraction peak intensity from the (111) plane of the face-centered cubic lattice structure is observed in a θ-2θ scan of an X-ray diffraction method.

[0314] From the viewpoint of improving the SNR, the intensity ratio of the X-ray diffraction of the seed layer 831 is preferably 60 cps / nm or more, more preferably 70 cps / nm or more, and even more preferably 80 cps / nm or more. Here, the intensity ratio of the X-ray diffraction of the seed layer 831 is a value (I / D (cps / nm)) obtained by dividing the intensity I (cps) of the X-ray diffraction of the seed layer 831 by the average thickness D (nm) of the seed layer 831.

[0315] The Cr, Ni, and Fe contained in the seed layer 831 preferably have an average composition represented by the following formula (2). Cr X (Ni Y Fe 100-Y ) 100-X ···(2) (In formula (2), X is within the range of 10≦X≦45, and Y is within the range of 60≦Y≦90.) When X is within the above range, the (111) orientation of the face-centered cubic lattice structure of Cr, Ni, and Fe is improved, resulting in a better SNR. Similarly, when Y is within the above range, the (111) orientation of the face-centered cubic lattice structure of Cr, Ni, and Fe is improved, resulting in a better SNR.

[0316] The average thickness of the seed layer 831 is preferably 5 nm or more and 40 nm or less. By setting the average thickness of the seed layer 831 within this range, the (111) orientation of the face-centered cubic lattice structure of Cr, Ni, and Fe can be improved, resulting in a better SNR. The average thickness of the seed layer 831 is determined in the same manner as for the magnetic layer 43 in the first embodiment. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of the seed layer 831.

[0317] (First and second base layers)

[0318] The first underlayer 832A contains Co and O having a face-centered cubic lattice structure and has a columnar (columnar crystal) structure. The first underlayer 832A containing Co and O provides substantially the same effect (function) as the second underlayer 832B containing Ru. The concentration ratio of the average atomic concentration of O to the average atomic concentration of Co ((average atomic concentration of O) / (average atomic concentration of Co)) is 1 or more. When the concentration ratio is 1 or more, the effect of providing the first underlayer 832A is improved, and a better SNR can be obtained.

[0319] From the viewpoint of improving the SNR, the columnar structure is preferably tilted. The tilt direction is preferably the longitudinal direction of the long magnetic recording medium 830. The longitudinal direction is preferred for the following reason: The magnetic recording medium 830 is a magnetic recording medium for so-called linear recording, and the recording tracks are parallel to the longitudinal direction of the magnetic recording medium 830. The magnetic recording medium 830 is also a so-called perpendicular magnetic recording medium. From the viewpoint of recording characteristics, it is preferable that the crystalline orientation axis of the magnetic layer 815 is vertical. However, the tilt of the columnar structure of the first underlayer 832A may cause the crystalline orientation axis of the magnetic layer 815 to tilt. In the magnetic recording medium 830 for linear recording, a configuration in which the crystalline orientation axis of the magnetic layer 815 is tilted in the longitudinal direction of the magnetic recording medium 830 in relation to the head magnetic field during recording can reduce the impact of the tilt of the crystalline orientation axis on recording characteristics compared to a configuration in which the crystalline orientation axis of the magnetic layer 815 is tilted in the width direction of the magnetic recording medium 830. In order to tilt the crystal orientation axis of the magnetic layer 815 in the longitudinal direction of the magnetic recording medium 830, it is preferable that the tilt direction of the columnar structure of the first underlayer 832A be the longitudinal direction of the magnetic recording medium 830 as described above.

[0320] The tilt angle of the columnar structure is preferably greater than 0° and not greater than 60°. When the tilt angle is greater than 0° and not greater than 60°, the tip shapes of the columns included in first foundation layer 832A change significantly, becoming roughly triangular mountain-shaped, which tends to enhance the effect of the granular structure, reduce noise, and improve SNR. On the other hand, when the tilt angle exceeds 60°, the tip shapes of the columns included in first foundation layer 832A change slightly, becoming less likely to become roughly triangular mountain-shaped, which tends to weaken the low-noise effect.

[0321] The average grain size of the columnar structure is 3 nm or more and 13 nm or less. If the average grain size is less than 3 nm, the average grain size of the columnar structure included in the magnetic layer 815 will be small, which may reduce the ability of current magnetic materials to retain data. On the other hand, if the average grain size is 13 nm or less, noise can be suppressed and a better SNR can be obtained.

[0322] The average thickness of the first underlayer 832A is preferably 10 nm or more and 150 nm or less. When the average thickness of the first underlayer 832A is 10 nm or more, the (111) orientation of the face-centered cubic lattice structure of the first underlayer 832A is improved, resulting in a better SNR. On the other hand, when the average thickness of the first underlayer 832A is 150 nm or less, the columnar grain size can be prevented from increasing. Therefore, noise can be suppressed and a better SNR can be obtained. The average thickness of the first underlayer 832A is determined in the same manner as the magnetic layer 43 in the first embodiment. However, the magnification of the TEM image is appropriately adjusted depending on the thickness of the first underlayer 832A.

[0323] The second underlayer 832B preferably has the same crystal structure as the magnetic layer 815. When the magnetic layer 815 contains a Co-based alloy, the second underlayer 832B preferably contains a material with a hexagonal close-packed (hcp) structure similar to that of the Co-based alloy, with the c-axis of the structure oriented perpendicular to the film surface (i.e., in the film thickness direction). This is because it enhances the orientation of the magnetic layer 815 and can achieve relatively good lattice constant matching between the second underlayer 832B and the magnetic layer 815. As a material with a hexagonal close-packed structure, a material containing Ru is preferably used, and specifically, Ru alone or a Ru alloy is preferably used. Examples of Ru alloys include Ru alloy oxides such as Ru-SiO2, Ru-TiO2, and Ru-ZrO2.

[0324] The average thickness of the second underlayer 832B may be thinner than that of an underlayer in a typical magnetic recording medium (e.g., an underlayer containing Ru), and can be, for example, 1 nm to 5 nm. Because the seed layer 831 and the first underlayer 832A having the above-described configuration are provided under the second underlayer 832B, a good SNR can be obtained even if the average thickness of the second underlayer 832B is thin as described above. The average thickness of the second underlayer 832B is determined in the same manner as for the magnetic layer 43 in the first embodiment. However, the magnification of the TEM image is appropriately adjusted depending on the thickness of the second underlayer 832B.

[0325] (effect)

[0326] The magnetic recording cartridge according to the second embodiment, even when using magnetic recording medium 830 instead of magnetic recording medium 810, can provide a magnetic recording cartridge that, like the first embodiment, allows the longitudinal width of magnetic recording medium 830 to be adjusted by adjusting the running tension of the tape system or changing the winding direction, even when stored in a high-temperature environment of 60°C or higher.

[0327] The magnetic recording medium 830 includes a seed layer 831 and a first underlayer 832A between a base layer 811 and a second underlayer 832B. The seed layer 831 contains Cr, Ni, and Fe and has a face-centered cubic lattice structure, with the (111) plane of this face-centered cubic structure preferentially oriented parallel to the surface of the base layer 811. The first underlayer 832A contains Co and O, and has a columnar structure in which the ratio of the average atomic concentration of O to the average atomic concentration of Co is 1 or greater and the average grain size is 3 nm or greater and 13 nm or less. This allows the thickness of the second underlayer 832B to be reduced, minimizing the use of Ru, an expensive material, and realizing a magnetic layer 815 with good crystal orientation and high coercivity.

[0328] The Ru contained in the second underlayer 832B has the same hexagonal close-packed lattice structure as Co, the main component of the magnetic layer 815. Therefore, Ru has the effect of simultaneously improving the crystalline orientation and granularity of the magnetic layer 815. To further improve the crystalline orientation of the Ru contained in the second underlayer 832B, the first underlayer 832A and seed layer 831 are provided below the second underlayer 832B. In the magnetic recording medium 830, the first underlayer 832A containing inexpensive CoO and having a face-centered cubic lattice structure achieves substantially the same effect (function) as the second underlayer 832B containing Ru. This allows the thickness of the second underlayer 832B to be reduced. To improve the crystalline orientation of the first underlayer 832A, the seed layer 831 containing Cr, Ni, and Fe is provided.

[0329] 4. Working Example

[0330] Hereinafter, the present technology will be specifically explained using examples, but the present technology is not limited to these examples.

[0331] In the following examples and comparative examples, the loss modulus of the base layer of the magnetic tape is a value determined by the measurement method described in the first embodiment.

[0332] [Width change amount]

[0333] The amount of change in width was determined by the measurement method described in the first embodiment.

[0334] [Example 1] (Preparation process of paint for forming magnetic layer) The magnetic layer-forming paint was prepared as follows. First, a first composition having the following formulation was kneaded using an extruder. Next, the kneaded first composition and a second composition having the following formulation were added to a stirring tank equipped with a disperser and premixed. Next, further mixing was performed using a Dynomill and filtering was performed to prepare the magnetic layer-forming paint.

[0335] (First composition) Barium ferrite (BaFe 12 O 19 ) Magnetic powder: 100 parts by mass (Hexagonal plate shape, average aspect ratio: 3.0, average particle volume: 1600nm 3 ) Polyurethane resin (number average molecular weight Mn: 25,000, Tg: 110°C): 52 parts by mass (Resin solution: 30% resin by mass, 70% cyclohexanone by mass) Aluminum oxide powder: 5 parts by mass (α-Al2O3, average particle size 0.1μm) Carbon black: 2 parts by mass (Manufactured by Tokai Carbon Co., Ltd., product name: Seest TA)

[0336] (Second composition) Polyurethane resin (number average molecular weight Mn: 25,000, Tg: 110°C): 4.7 parts by mass (Resin solution: 30% resin by mass, 70% cyclohexanone by mass) n-Butyl stearate: 2 parts by mass Methyl ethyl ketone: 121.3 parts by mass Toluene: 121.3 parts by mass Cyclohexanone: 60.7 parts by mass

[0337] Finally, 3.4 parts by mass of polyisocyanate (product name: Coronate L, manufactured by Tosoh Corporation) and 2 parts by mass of stearic acid were added as a curing agent to the magnetic layer-forming coating material prepared as described above.

[0338] (Preparation process of paint for forming base layer) The paint for forming the primer layer was prepared as follows. First, the third composition having the following composition was kneaded using an extruder. Next, the kneaded third composition and the fourth composition having the following composition were added to a stirring tank equipped with a disperser and premixed. Subsequently, further mixing was performed using a Dynomill and filtering was performed to prepare the paint for forming the primer layer.

[0339] (Third composition) Acicular iron oxide powder: 100 parts by mass (α-Fe2O3, average major axis length 0.12μm) Polyurethane resin (Tg: 110 ° C): 55.6 parts by mass (Resin solution: 30% resin by mass, 70% cyclohexanone by mass) Carbon black: 10 parts by mass (Average particle size 20nm)

[0340] (4th composition) Polyurethane resin (Tg: 110 ° C): 18.5 parts by mass (Resin solution: 30% resin by mass, 70% cyclohexanone by mass) n-Butyl stearate: 2 parts by mass Methyl ethyl ketone: 108.2 parts by mass Toluene: 108.2 parts by mass Cyclohexanone: 18.5 parts by mass

[0341] Finally, 4.45 parts by mass of polyisocyanate (trade name: Coronate L, manufactured by Tosoh Corporation) as a curing agent and 2 parts by mass of stearic acid were added to the coating material for forming an undercoat layer prepared as described above.

[0342] (Preparation process of paint for forming back layer) The coating material for forming a back layer was prepared as follows: The following raw materials were mixed in a stirring tank equipped with a disperser, and the mixture was filtered to prepare the coating material for forming a back layer. Carbon black (manufactured by Asahi Carbon Co., Ltd., product name: #80): 100 parts by mass Polyester polyurethane: 100 parts by mass (Nippon Polyurethane Co., Ltd., product name: N-2304) Methyl ethyl ketone: 500 parts by mass Toluene: 400 parts by mass Cyclohexanone: 100 parts by mass

[0343] (Film forming process) Using the coating material prepared as described above, a base layer (hereinafter also referred to as the "lower layer" in Table 1) was formed on a long polyethylene terephthalate film (hereinafter referred to as the "PET film"), which was a non-magnetic support (base layer), so that the average thickness after calendaring was 1.33 μm. m A magnetic layer (hereinafter also referred to as "upper layer" in Table 1) was formed as follows so that the thickness of the magnetic layer was 1.40 μm. First, a base layer-forming paint was applied to the film and dried to form a base layer on the film. Next, a magnetic layer-forming paint was applied to the base layer and dried to form a magnetic layer on the base layer. During drying of the magnetic layer-forming paint, a solenoid coil was used to magnetically orient the magnetic powder in the thickness direction of the film. The application time of the magnetic field to the magnetic layer-forming paint was also adjusted to set the squareness ratio S2 in the thickness direction (perpendicular direction) of the magnetic tape to 65%.

[0344] Next, the film on which the underlayer and magnetic layer were formed was subjected to a calendering treatment to obtain an average thickness t b The back layer was applied and dried so that the thickness was 0.30 μm. The film on which the underlayer, magnetic layer, and back layer were formed was then subjected to a curing treatment. Subsequently, a calendering treatment was performed to smooth the surface of the magnetic layer. The calendering conditions (temperature) were adjusted so that the interlayer friction coefficient μ between the magnetic surface and the back surface was approximately 0.5, and then the film was re-cured to a thickness of 0.30 μm. T A magnetic tape with a thickness of 5.3 μm was obtained.

[0345] (Cutting process) The magnetic tape obtained as described above was cut into 1 / 2 inch (12.65 mm) widths and wound around a core to obtain pancakes.

[0346] The magnetic tape obtained as described above had the properties shown in Table 1. For example, the loss modulus of the base layer of the magnetic tape at 65°C was 0.07 GPa.

[0347] The 1 / 2-inch-wide magnetic tape was wound onto a reel provided inside a cartridge case to obtain a magnetic recording cartridge. A servo pattern was recorded on the magnetic tape. The servo pattern consisted of a series of V-shaped servo frames, and the servo frames were pre-recorded in two or more rows parallel to the longitudinal direction at known intervals. The magnetic tape was wound into the magnetic recording cartridge with a tension of 0.55 N and stored at 65°C and 40% RH for 360 hours. The servo band pitch was then measured while the magnetic tape housed in the magnetic recording cartridge was being run in the forward direction so as to be wound into a magnetic recording and playback device. The servo band pitch in the longitudinal direction was also measured for the magnetic tape housed in the magnetic recording cartridge in its initial state before storage, and the width change, expressed as the ratio of the servo band pitch after storage to the servo band pitch in the initial state, was calculated. The results are shown in Figure 28. In Figure 28, the horizontal axis indicates the position in the longitudinal direction of the magnetic tape. In FIG. 28, the position of the outermost (outside winding) end (BOT) of the magnetic tape wound around the tape reel is designated as 0, and the position of the innermost (inside winding) end (hereinafter also referred to as EOT) of the magnetic tape wound around the tape reel is designated as 84, and the total length of the magnetic tape was divided into 84 equal parts. In FIG. 28, the vertical axis indicates the width change after storage at 65°C, 40% RH, and 360 hours, and indicates width after storage / width before storage. In FIG. 28, when the width change indicates a negative value, it means that the width of the magnetic tape is narrower after storage than before storage, and when the width change indicates a positive value, it means that the width of the magnetic tape is wider after storage than before storage. Note that the explanation for FIG. 28 applies to the horizontal and vertical axes in FIGS. 29 to 39 as well. As shown in FIG. 28, the width change at the outer winding end at positions 0 to 20 is negative, the width change at the inner winding end at positions 60 to 84 is positive, and the width change is 0 ppm between positions 55 and 56.

[0348] [Example 2] A magnetic tape was obtained in the same manner as in Example 1, except that a polyethylene naphthalate film (hereinafter referred to as "PEN film") was used as the base layer material. As in Example 1, a magnetic recording cartridge was manufactured using the magnetic tape, and a servo pattern was recorded on the magnetic tape. The results of the width change in the longitudinal direction of the magnetic tape are shown in Figure 29. As shown in Figure 29, the width change on the outside of the winding at positions 0 to 20 was a negative value, the width change on the inside of the winding at positions 60 to 84 was a positive value, and the width change was 0 ppm between positions 59 and 60.

[0349] [Example 3] A magnetic tape was obtained in the same manner as in Example 1, except that a polyether ether ketone film (hereinafter referred to as "PEEK film") was used as the base layer material, the average thickness of the base layer was 4.0 μm, the average thicknesses of the upper and lower layers were 1.2 μm, the average thickness of the back layer was 0.4 μm, and the average total thickness was 5.6 μm. As in Example 1, a magnetic recording cartridge was manufactured using the magnetic tape, and a servo pattern was recorded on the magnetic tape. The results of the width change in the longitudinal direction of the magnetic tape are shown in FIG. 31. As shown in FIG. 31, the width change on the outside of the winding at positions 0 to 20 was a negative value, the width change on the inside of the winding at positions 60 to 84 was a positive value, and the width change was 0 ppm between positions 37 and 38.

[0350] [Example 4] (SUL film formation process) First, a CoZrNb layer (SUL) having an average thickness of 10 nm was formed on the surface of a long polymer film serving as a non-magnetic support under the following film formation conditions: A PEN film was used as the polymer film. Film formation method: DC magnetron sputtering method Target: CoZrNb target Gas type: Ar Gas pressure: 0.1 Pa

[0351] (First seed layer formation process) Next, a TiCr layer (first seed layer) having an average thickness of 5 nm was formed on the CoZrNb layer under the following film formation conditions. Sputtering method: DC magnetron sputtering method Target: TiCr target Ultimate vacuum: 5×10 -5 Pa Gas type: Ar Gas pressure: 0.5 Pa

[0352] (Second seed layer formation process) Next, a NiW layer (second seed layer) having an average thickness of 10 nm was formed on the TiCr layer under the following film formation conditions. Sputtering method: DC magnetron sputtering method Target: NiW target Ultimate vacuum: 5×10 -5 Pa Gas type: Ar Gas pressure: 0.5 Pa

[0353] (First Underlayer Forming Process) Next, a Ru layer (first underlayer) having an average thickness of 0.1 μm was formed on the NiW layer under the following film formation conditions. Sputtering method: DC magnetron sputtering method Target: Ru target Gas type: Ar Gas pressure: 0.5 Pa

[0354] (Second Underlayer Forming Process) Next, a Ru layer (second underlayer) having an average thickness of 0.1 μm was formed on the Ru layer under the following film formation conditions. Sputtering method: DC magnetron sputtering method Target: Ru target Gas type: Ar Gas pressure: 1.5Pa

[0355] (Magnetic layer deposition process) Next, a (CoCrPt)-(SiO2) layer (magnetic layer) having an average thickness of 12 nm was formed on the Ru layer under the following film formation conditions. Film formation method: DC magnetron sputtering method Target: (CoCrPt)-(SiO2) target Gas type: Ar Gas pressure: 1.5Pa

[0356] (Protective layer deposition process) Next, a carbon layer (protective layer) having an average thickness of 5 nm was formed on the magnetic layer under the following film formation conditions. Film formation method: DC magnetron sputtering method Target: Carbon target Gas type: Ar Gas pressure: 1.0 Pa

[0357] (Lubrication layer formation process) Next, a lubricant was applied onto the protective layer to form a lubricating layer.

[0358] (Back layer deposition process) Next, a coating material for forming a back layer is applied to the surface opposite the magnetic layer and dried to form a layer with an average thickness of t b This resulted in a back layer with an average thickness of t T A magnetic tape with a thickness of 4.6 μm was obtained.

[0359] (Cutting process) The magnetic tape obtained as described above was cut into a width of 1 / 2 inch (12.65 mm).

[0360] The magnetic tape obtained as described above was used to manufacture a magnetic recording cartridge, and a servo pattern was recorded on the magnetic tape, in the same manner as in Example 1. The results of the width change in the longitudinal direction of the magnetic tape are shown in Figure 31. As shown in Figure 31, the width change on the outside of the winding at positions 0 to 20 was a negative value, the width change on the inside of the winding at positions 60 to 84 was a positive value, and the width change was 0 ppm between positions 31 and 32.

[0361] [Comparative Example 1] A magnetic tape was obtained in the same manner as in Example 2, except that the average thickness of the base layer was 4.0 μm, the average thickness of the upper and lower layers was 1.2 μm, the average thickness of the back layer was 0.4 μm, and the average total thickness was 5.6 μm. The polyurethane resin blended into the magnetic layer-forming paint and the primer layer-forming paint had a Tg of 70°C. Polyisocyanate was not added as a curing agent to the primer layer-forming paint. A magnetic recording cartridge was manufactured using the magnetic tape in the same manner as in Example 2, and a servo pattern was recorded on the magnetic tape. The results of the width change in the longitudinal direction of the magnetic tape are shown in FIG. 32. As shown in FIG. 32, the width change on the outer side of the winding at positions 0 to 20 was a positive value, and the width change on the inner side of the winding at positions 60 to 84 was also a positive value.

[0362] Comparative Example 2 A magnetic tape was manufactured in the same manner as in Example 1, except that the average thickness of the base layer was 4.0 μm, the average thickness of the upper and lower layers was 1.2 μm, the average thickness of the back layer was 0.4 μm, and the average total thickness was 5.6 μm. The polyurethane resin blended into the magnetic layer-forming paint and the primer layer-forming paint had a Tg of 70°C. 1.7 parts by mass of polyisocyanate (product name: Coronate L, manufactured by Tosoh Corporation) was added as a curing agent to the magnetic layer-forming paint, and 2.23 parts by mass of polyisocyanate (product name: Coronate L, manufactured by Tosoh Corporation) was added as a curing agent to the primer layer-forming paint. A magnetic recording cartridge was manufactured using the magnetic tape in the same manner as in Example 1, and a servo pattern was recorded on the magnetic tape. The results of the width change in the longitudinal direction of the magnetic tape are shown in FIG. 33. As shown in FIG. 33, the width change on the outer side of the winding at positions 0 to 20 was a positive value, and the width change on the inner side of the winding at positions 60 to 84 was also a positive value.

[0363] Comparative Example 3 A magnetic tape was obtained in the same manner as in Example 2, except that a polyurethane resin with a Tg of 70°C was used as the resin blended into the magnetic layer-forming paint and the primer layer-forming paint, and no polyisocyanate was added as a curing agent to the primer layer-forming paint. As in Example 2, a magnetic recording cartridge was manufactured using the magnetic tape, and a servo pattern was recorded on the magnetic tape. The results of the width change in the longitudinal direction of the magnetic tape are shown in Figure 34. As shown in Figure 34, the width change on the outside of the winding at positions 0 to 20 was a negative value, and the width change on the inside of the winding at positions 60 to 84 was also a negative value.

[0364] Comparative Example 4 A magnetic tape was obtained in the same manner as in Example 2, except that an aramid film (hereinafter referred to as "ARAMID film") was used as the base layer, a polyurethane resin with a Tg of 70°C was used as the resin blended into the magnetic layer-forming paint and the primer layer-forming paint, and no polyisocyanate was added as a curing agent to the primer layer-forming paint. As in Example 2, a magnetic recording cartridge was manufactured using the magnetic tape, and a servo pattern was recorded on the magnetic tape. The results of the width change in the longitudinal direction of the magnetic tape are shown in Figure 35.

[0365] [Running characteristics after rewinding and long-term storage]

[0366] After storing the magnetic recording cartridge for two weeks at 65°C and 40% RH, the magnetic tape was wound around the take-up reel 32 of the magnetic recording and reproducing device 30, with the winding direction reversed, and then stored for another two weeks. After that, the entire magnetic tape was recorded and reproduced using the magnetic recording and reproducing device 30, and the running characteristics were given a rating based on the following three-level criteria. A rating of "B" or "C" indicated an undesirable rating. When the entire magnetic tape could be recorded and reproduced, the amount of change in width in the data band at the center of the magnetic tape's width from before storage was measured, and the difference between the minimum and maximum width portions was calculated. A: No abnormalities occurred (no failures occurred). B: After several runs, the servo cannot be read and the system stops with an error. C: The servo cannot be read and the system will stop immediately due to a system error.

[0367] Table 1 shows the configurations and evaluation results of the magnetic tapes of Examples 1 to 4 and Comparative Examples 1 to 4. Also, Figures 28 to 38 are diagrams showing the amount of width change in the longitudinal direction of the magnetic tapes of Examples 1 to 4 and Comparative Examples 1 to 4.

[0368] [Table 1]

[0369] The symbols in Table 1 represent the following measured values. t T : Average thickness of magnetic tape (unit: μm) t m : Average thickness of magnetic layer (unit: nm) t b : Average thickness of back layer (unit: μm)

[0370] The results shown in Table 1 reveal the following:

[0371] All of the magnetic tapes of Examples 1 to 4 were stored for two weeks in an environment of 65°C and 40% RH, then rewound so that the outer and inner windings were reversed, and after another two weeks of storage in the same environment, the entire tape was played back in a magnetic recording and playback device. The running characteristics were evaluated as A, with no failures occurring, and good running characteristics were observed. Therefore, it can be seen that the magnetic recording cartridge according to the present technology is suitable for storage and use in high-temperature environments of 60°C or higher.

[0372] The results of the change in tape width in the longitudinal direction for Example 1 and Comparative Example 2 show that by having the sign of the width change Δout on the outside of the reel different from the sign of the width change Δin on the inside of the reel, the magnetic recording tape can improve its running characteristics after being rewound and stored for a long period of time.

[0373] A comparison between Example 2 and Comparative Example 3 shows that when (inner width change Δin) - (outer width change Δout) after storage at 65°C for 360 hours is 800 ppm or less, the running properties after rewinding and long-term storage can be improved.

[0374] A comparison between Example 2 and Comparative Example 1 shows that when the total longitudinal length of the magnetic tape is taken as 100%, the width change Δ of the magnetic recording medium after storage at 65°C for 360 hours is 0 ppm at 59 to 60, which is located 25% to 75% from the outer end of the winding, and therefore the running characteristics after rewinding and long-term storage can be improved.

[0375] A comparison between Example 2 and Comparative Example 4 shows that the loss modulus of the base layer at 65° C. is 0.40 GPa or less, which makes it possible to improve the running characteristics after rewound and long-term storage.

[0376] A comparison of the results of Example 4 with those of the other Examples shows that even with a vacuum thin film type (sputter type) magnetic recording tape, evaluation results similar to those of a coated type magnetic recording tape can be obtained.

[0377] Although the embodiments and examples of the present technology have been specifically described above, the present technology is not limited to the above-described embodiments and examples, and various modifications based on the technical ideas of the present technology are possible.

[0378] For example, the configurations, methods, steps, shapes, materials, and numerical values, etc., given in the above-described embodiments and examples are merely examples, and different configurations, methods, steps, shapes, materials, and numerical values, etc., may be used as necessary. Furthermore, the chemical formulas of compounds, etc., are representative, and are not limited to the valences, etc., given as long as they are general names of the same compounds.

[0379] Furthermore, the configurations, methods, processes, shapes, materials, numerical values, and the like of the above-described embodiments and examples can be combined with each other without departing from the spirit of the present technology.

[0380] Furthermore, in this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in one stage may be replaced with the upper or lower limit of a numerical range in another stage. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types.

[0381] The present technology can also be configured as follows. [1] A magnetic recording medium having a base layer; a reel; The base layer has a loss modulus of 0.40 GPa or less at 65°C, the magnetic recording medium is wound on the reel, and When the amount of change in width was measured over the entire length of the magnetic recording medium after storage at 65°C for 360 hours, The sign of the width change amount Δout on the outer side of the winding is different from the sign of the width change amount Δin on the inner side of the winding, and the width change amount is 0 ppm at any of two portions sandwiching a center line of the entire length of the magnetic recording medium when the entire length of the magnetic recording medium is divided into four equal parts; Magnetic recording cartridge. [2] The magnetic recording cartridge according to [1], wherein the width change amount Δin is a positive value and the width change amount Δout is a negative value. [3] The magnetic recording cartridge according to [1] or [2], wherein, when the total length of the magnetic recording medium in the longitudinal direction is taken as 100%, the width change Δ of the magnetic recording medium after storage at 65°C for 360 hours is 0 ppm at a position 25% to 75% from the outer end of the winding. [4] The magnetic recording cartridge according to any one of [1] to [3], wherein (the amount of change in width Δin)−(the amount of change in width Δout) is 800 ppm or less. [5] The magnetic recording cartridge according to any one of [1] to [4], wherein the storage modulus of the base layer is 8.0 GPa or less. [6] The magnetic recording cartridge according to any one of [1] to [5], wherein the base layer is formed from PET (polyethylene terephthalate), PEN (polyethylene naphthalate), or PEEK (polyether ether ketone). [7] The average thickness t of the magnetic recording medium T The magnetic recording cartridge according to any one of [1] to [6], wherein the thickness is 5.6 μm or less. [8] The average thickness t of the magnetic recording medium T The magnetic recording cartridge according to any one of [1] to [6], wherein the thickness is 5.4 μm or less. [9] The average thickness t of the base layer B The magnetic recording cartridge according to any one of [1] to [8], wherein the thickness is 5.0 μm or less.

[10] The average thickness t of the base layer B The magnetic recording cartridge according to any one of [1] to [8], wherein the thickness is 4.6 μm or less.

[11] The magnetic recording medium comprises a magnetic layer, The magnetic recording cartridge according to any one of [1] to

[10] , wherein the magnetic layer contains magnetic powder.

[12] The magnetic recording medium comprises a magnetic layer, The magnetic recording cartridge according to any one of [1] to

[10] , wherein the magnetic layer is a sputtered layer.

[13] The magnetic recording cartridge is wound around a reel and is housed in the magnetic recording cartridge, When the width change amount was measured over the entire length after storing the film wound on the reel at 65°C for 360 hours, The sign of the width change amount Δout on the outer side of the winding is different from the sign of the width change amount Δin on the inner side of the winding, and The width change amount is 0 ppm at any of two portions on either side of the center line of the entire length when the entire length is divided into four equal parts, and A magnetic recording medium having a base layer with a loss modulus at 65°C of 0.40 GPa or less. [Explanation of symbols]

[0382] 1. Magnetic recording media 10 Magnetic recording cartridge 13 Tape reel 41 Base Layer 42 Base layer 43 Magnetic layer 44 Back layer

Claims

1. a magnetic recording medium having a base layer; a reel; the base layer has a loss modulus at 65°C of 0.40 GPa or less; the magnetic recording medium is wound on the reel, and When the amount of change in width was measured over the entire length of the magnetic recording medium after storage at 65° C. for 360 hours, The sign of the width change amount Δout on the outer side of the winding is different from the sign of the width change amount Δin on the inner side of the winding, and the width change amount is 0 ppm at any of two portions sandwiching a center line of the entire length of the magnetic recording medium when the entire length of the magnetic recording medium is divided into four equal parts; Magnetic recording cartridge.

2. 2. The magnetic recording cartridge according to claim 1, wherein the width change amount .DELTA.in is a positive value and the width change amount .DELTA.out is a negative value.

3. 2. The magnetic recording cartridge according to claim 1, wherein, when the total length of the magnetic recording medium in the longitudinal direction is taken as 100%, the amount of change in width Δ of the magnetic recording medium after storage at 65° C. for 360 hours is 0 ppm at a position 25% to 75% from the outer end of the winding.

4. 2. The magnetic recording cartridge according to claim 1, wherein (the amount of change in width Δin) - (the amount of change in width Δout) is 800 ppm or less.

5. 2. The magnetic recording cartridge of claim 1, wherein the storage modulus of the base layer at 65[deg.] C. is 8.0 GPa or less.

6. 2. The magnetic recording cartridge of claim 1, wherein the base layer is formed from PET (polyethylene terephthalate), PEN (polyethylene naphthalate), or PEEK (polyether ether ketone).

7. The average thickness t of the magnetic recording medium Ｔ 2. The magnetic recording cartridge of claim 1, wherein the thickness is 5.6 [mu]m or less.

8. The average thickness t of the magnetic recording medium Ｔ 2. The magnetic recording cartridge of claim 1, wherein the thickness is 5.4 [mu]m or less.

9. The average thickness t of the base layer Ｂ 2. The magnetic recording cartridge of claim 1, wherein the thickness is 5.0 [mu]m or less.

10. The average thickness t of the base layer Ｂ 2. The magnetic recording cartridge of claim 1, wherein the thickness is 4.6 [mu]m or less.

11. the magnetic recording medium comprises a magnetic layer, 10. The magnetic recording cartridge of claim 1, wherein the magnetic layer comprises magnetic powder.

12. the magnetic recording medium comprises a magnetic layer, 2. The magnetic recording cartridge of claim 1, wherein the magnetic layer is a sputtered layer.

13. The magnetic recording cartridge is wound around a reel and is housed in the magnetic recording cartridge, When the width change amount was measured over the entire length after storing the film wound on the reel at 65°C for 360 hours, The sign of the width change amount Δout on the outer side of the winding is different from the sign of the width change amount Δin on the inner side of the winding, and The width change amount is 0 ppm at any of two portions on either side of the center line of the entire length when the entire length is divided into four equal parts, and A base layer having a loss modulus at 65°C of 0.40 GPa or less. Magnetic recording media.

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