JP2002260217A - Magnetic tape, its cleaning method and optical servo track forming and cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic tape which has a high S/N ratio in optical servo signal and hardly causes a dropout caused by its disordered rolling and the unnecessary adherence of powder to it and the like, a cleaning method suitable for obtaining such a magnetic tape and an optical servo track forming and cleaning device. SOLUTION: A back coat layer 2 containing a non-magnetic powder which contains carbon black as a component and a binder is provided completely on the surface of a non-magnetic base material 3 opposite to a magnetic layer 4. A servo pattern 5 consisting of a concave part for optical servo is formed in the back coat layer 2, and an average light reflectivity at the flat part of the back coat layer 2 is at least 8.5% and a maximum variation rate in light reflectivity at the flat part depending on the location of the magnetic tape is set to be 10% or below. Combusted gases adhered to the surface of the back coat layer are blown off by spraying solid carbon dioxide to the surface of the back coat layer 2. A cleaning method with a kind of soft brush contacted is also an effective means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape provided with a concave portion for an optical servo track in a back coat layer, a cleaning method thereof, and an optical servo track forming / cleaning apparatus.

[0002]

2. Description of the Related Art Magnetic tapes have various uses such as audio tapes, video tapes, and tapes for computer data backup. Of these, for example, in the field of data backup tapes (backup tapes), several tens of G
Although those having a storage capacity of B or more are commercialized, it is indispensable to increase the capacity of the hard disk in order to cope with a further increase in the capacity of the hard disk in the future. Further, in order to increase the access speed and the transfer speed, it is necessary to increase the tape feeding speed and the relative speed between the tape and the head.

In order to increase the capacity per one roll of backup tape, the total thickness of the tape is reduced to increase the length of the tape per roll, and the thickness of the magnetic layer is extremely thin to 0.3 μm or less. Therefore, it is necessary to reduce the thickness demagnetization to shorten the recording wavelength, and to reduce the track width to 15 μm or less to increase the recording density in the width direction.

If the thickness of the magnetic layer is extremely thin, 0.3 μm or less, the durability deteriorates. Therefore, it is preferable to provide at least one undercoat layer between the nonmagnetic support and the magnetic layer. Further, when the recording wavelength is shortened, the influence of the spacing between the magnetic layer and the magnetic head is increased. Therefore, if the magnetic layer has a large protrusion or dent, the error rate increases due to a decrease in output due to spacing loss.

[0005] When the thickness of the magnetic layer is extremely reduced to 0.3 µm or less and the recording wavelength is shortened, the magnetic flux leaking from the magnetic recording medium is reduced. It is preferable to use a reproducing head (hereinafter, MR head) using a pattern element.

Further, the track width (track width of a signal recorded on a data track) is reduced to 1.5 μm or less,
If the recording density in the width direction is increased, a decrease in the reproduction output due to off-track becomes a problem, and therefore a track servo is required as a countermeasure.

[0007] One of such track servo systems is an optical track servo system. In this method, a concave portion for optical servo is formed by irradiating a laser beam or pressing with a stamper, and servo tracking is performed by optically detecting the concave portion.

Further, this type of optical track servo system includes a magnetic layer of a floppy disk (floppy (registered trademark) disk of an optical servo track system) as disclosed in JP-A-3-14087. In which a concave portion for optical servo is formed,
As disclosed in JP-A-254-254 and JP-A-11-213384, there is a magnetic tape in which a concave portion for an optical servo is formed in a back coat layer.

When a concave portion for optical servo is formed in the back coat layer, track servo is performed by detecting a difference in light reflectance between the concave portion and the flat portion in the back coat layer. That is, when light is applied to the back coat layer having such a concave portion, the light is diffusely reflected in the concave portion, so that the reflected light intensity entering the photodetector is weak, and the light is specularly reflected in the flat portion, so that the reflected light intensity is low. Although it becomes stronger, the above-described method utilizes this to track the servo track formed by the concave portion. Specifically, the servo of the magnetic recording track is performed by moving the magnetic head for recording / reproducing the magnetic layer in conjunction with the servo tracking of the back coat layer.

In this method, if a concave portion for optical servo is formed by a normal laser, the intensity of light reflection from the concave portion can be sufficiently reduced by irregular reflection. Since the intensity is small and the light reflectance of the flat portion greatly varies depending on the location, there is a problem that the S / N of the optical servo cannot be sufficiently high. The reason is that in the back coat layer of the conventional magnetic tape, only the tape running property is emphasized, and the light reflectance is not considered.

Further, when a concave portion is formed in the back coat layer by laser irradiation, stamper pressing, or the like, it is inevitable that a bulge occurs in a peripheral portion (concave end portion) of the concave portion, so that the following problem occurs. . That is, when the total thickness of the tape is 6 μm or less, the tape rigidity (ET ³ when the Young's modulus of the tape is E and the total thickness of the tape is T) becomes small, so that the winding tension during tape running is reduced. However, in this case, if the specific position of the magnetic tape is raised as described above, the track forming portion becomes extremely raised when the tape reel is wound up, and a so-called tape winding phenomenon occurs.

[0012] In addition, if there are such raised portions as described above, they protrude behind the recording layer (magnetic recording surface) of the magnetic tape, and irregularities are formed on the recording layer. As a result, the reproduction output decreases. Such a problem also arises. In addition, since the magnetic disk using the optical servo track method does not take up like a magnetic tape, even if the peripheral portion of the concave portion for the optical servo is raised, the above-described tape winding phenomenon and the reverse side of the tape may occur. There is no room for depression. That is, such a phenomenon becomes a problem only for a magnetic tape. In order to solve this problem, it is preferable that the height of the raised portion be equal to or less than the maximum projection height (PO) of the flat portion.

Further, in the method of forming a concave portion in the back coat layer by laser irradiation, the back coat layer is irradiated with laser light to burn off the coating surface with the energy and form a concave pattern, so that the productivity is high. However, a large amount of burned scum (burning scum) burned off by the laser during pattern formation becomes a powder and adheres to the concave portion and the periphery thereof. Leaving the combustion residue as it is causes not only contamination of the running system, but also a reduction in the optical reading S / N of the back coat layer and a dropout due to the adhesion of the combustion residue to the magnetic layer. become. In addition, the light reflectance of the flat portion of the surface of the back coat layer decreases, and the fluctuation of the reflectance in the longitudinal direction of the magnetic tape increases. This also causes a reduction in the optical reading S / N. For this reason, it is essential to remove combustion residues.

[0014] As a method of removing combustion scum generated when a concave portion for optical servo is formed by laser irradiation,
There is known a method of using solid CO ₂ to remove combustion residues from a floptical disk having a concave portion for optical servo (US Pat. No. 5,419,733). In the case of a disk-shaped floptical disk, the area to be cleaned is limited, and solid CO ₂ required for cleaning can be easily sprayed by rotating the disk at high speed many times.

[0015] However, if this is used as it is as the magnetic tape of the cleaning means, the magnetic tape is long object extending the area of interest for cleaning becomes enormous, disc shaped to yet blow multiple solid CO ₂ such as CO ₂ amount than that of the is mass,
There is a problem in efficiency. In addition, the burning swarf generated when the servo pattern is generated by laser irradiation is transferred to the magnetic tape by rewinding the magnetic tape, and the burning scum adheres to the drive guide roller and the magnetic head. There is no problem.

On the other hand, as a method of cleaning the surface of the tape-shaped magnetic tape, there is a method of cleaning by bringing a tape-shaped tissue cleaning tape into contact with the front and back surfaces of the magnetic tape. However, the cleaning effect of the flat portion is insufficient. The effect of cleaning the inside of the servo dot formed concavely by the laser is small. Also,
It is also conceivable to combine blade treatment with the above cleaning treatment.However, since the back coat layer has a lower strength than the magnetic layer, a strong blade treatment damages the back coat layer. Since the effect is lost, it is very difficult to set conditions and mass production is difficult. Further, there is almost no effect of cleaning the inside of the servo dot formed in a concave shape.

The present invention has been made to solve the above-mentioned problems.

[0018]

SUMMARY OF THE INVENTION The present inventors have studied a magnetic tape having a high S / N of an optical servo signal.
In order to increase the S / N, the average value of the light reflectance of the flat portion in the back coat layer is set to 8.5% or more, and the magnetic tape position of the light reflectance of the flat portion (location on the magnetic tape) Rate of change [<(light reflectance-average value of light reflectance)]
Maximum value of absolute value> ÷ (average value of light reflectance) × 100]
To 10% or less.

A preferred method for making the average value of the light reflectance of the flat portion in the back coat layer 8.5% or more and making the variation of the light reflectance of the flat portion depending on the location 10% or less includes backing. Non-magnetic powder content of coat layer [(non-magnetic powder weight) / (non-magnetic powder weight + binder weight) × 10
0] is 50% by weight or more, and an atomic force microscope (AF
Surface roughness Ra of flat portion of back coat layer measured in M)
Is controlled to 30 nm or less, and the half width of the variation of the surface roughness Ra depending on the position of the magnetic tape is set to 5 nm or less.

It is preferable that the proportion of carbon black in the non-magnetic powder be 80% by weight or more, since a concave portion (servo hole) for optical servo is easily formed by a laser beam. Further, it is preferable to add a total of 20% by weight or less of iron oxide (for example, red iron oxide) together with carbon black because the strength of the back coat layer is increased.

The inventors of the present invention have studied in detail how to solve the problem of the tape winding turbulence of a magnetic tape having a total thickness of 6 μm or less. As a result, the total thickness of the magnetic tape is T, and the concave end of the back coat layer is T. H / T is 1 when the average height per 100 convex portions of (the peripheral portion of the concave portion for optical servo) is H.
It has been found that setting the ratio to / 50 or less can prevent the problem of tape winding disorder. H / T is more preferably 1/100 or less.

Another object of the present invention is to provide combustion scum (powder or the like) generated when a concave portion for optical servo is formed on a surface of a back coat layer of a magnetic tape by laser irradiation, and particularly adhered to the inside and periphery of the concave portion. It is an object of the present invention to provide a method and an apparatus capable of efficiently removing combustion waste, and to obtain a magnetic tape having a low error rate. As a result of examining a method for efficiently removing combustion residues generated by laser irradiation, it was found that a cleaning method using CO _{2 and} a cleaning method using a brushed body were effective. Although the cleaning method according to CO ₂ that require relatively large apparatus, consumables relatively running cost is low only CO _2. On the other hand, the cleaning method using a raised body consumes the raised body,
It has the advantage that the device is relatively simple.

First, a cleaning method using CO ₂ will be described. While the magnetic tape is running in the longitudinal direction, the back coat layer is irradiated with laser light to form a concave portion for optical servo in the back coat layer. It has been found that if solid CO ₂ is sprayed on the surface of the coat layer, it is possible to remove combustion scum adhering to and inside the optical servo recess only by running the magnetic tape once. That is, as illustrated in FIGS. 1 to 3, while the magnetic tape 1 to be cleaned is running at a high speed (for example, a speed of about 10 m / sec), the solid CO 2 is applied to the surface of the back coat layer 2. _By spraying ₂ (CO ₂ , which is a liquid at the time of injection and becomes solid immediately after the injection), it has been found that the powder adhering to the surface of the back coat layer 2 can be efficiently removed. FIG.
In FIG. 3 to FIG. 3, reference numeral 3 denotes a nonmagnetic support, 4 denotes a magnetic layer, 5 denotes a servo pattern including a number of concave portions for optical servo, and 6 denotes an undercoat layer.

Such a solid CO_Two Sprayed with fuel
It is considered that burnt waste can be removed efficiently as follows.
You. That is, sprayed on the surface of the back coat layer
CO _Two Is below a certain temperature and above a certain pressure.
Liquid, but the pressure drops sharply after injection.
Changes from a liquid to a solid to form particles or fine particles
It becomes dry ice. This dry ice is CO_Two Squirting
After being sprayed from the spraying nozzle 15
The surface of the back coat layer 2 of
And scatters around the area (carbonated in a short time)
Gas), but when it comes into contact with the backcoat layer surface
The powder (mainly, combustion waste) adhering thereto is adsorbed.
As a result, combustion residues on the surface of the back coat layer are separated.
It will be separated and removed. At this time, it is shown in FIG.
Yeah, CO_Two Spray area (part to be sprayed shown in FIG. 7)
The area around B) is suctioned by suction means such as the suction nozzle 16.
This makes it possible to more efficiently remove combustion waste.

FIG. 3 shows a suction nozzle 1 having a suction port 16a having a width larger than the tape width as a suction means.
6 shows an example in which 6 is disposed above the surface of the back coat layer, but the suction means is not limited to this. For example, as shown in FIG. 4, when viewed from the direction opposite to the running direction of the magnetic tape 1 (in FIG. 4, viewed from above the paper surface), the surface of the magnetic tape 1 on the back coat layer 2 side and both edges (magnetic A suction means 16 having a suction port 16a for covering both ends along the longitudinal direction of the tape 1) may be used, or as shown in FIG. Look at the suction port 1 that surrounds the entire tape
A suction means 16 having 6a may be used. Although not shown, after not block the travel of the magnetic tape, including an injection nozzle 15 for CO ₂ blowing CO ₂
Suction means that covers the entire spray area may be used.

FIG. 6 shows an example of an arrangement pattern (servo pattern) of concave portions for optical servo formed by laser irradiation. In the illustration, the tape width is 12.64 mm
(1/2 inch) is an example of the servo pattern 5 on the magnetic tape 1. In this example, four rows of bands 5 each extending in the tape width direction in the tape width direction are provided.
a is formed. The width of one band 5a is about 0.4 mm
It is. Each band 5a microscopically has a configuration in which concave portions for optical servo are arranged in the longitudinal direction of the tape as one row, and a plurality of concave rows are arranged at intervals in the tape width direction. . Powder generated by laser irradiation,
Since the servo pattern is most adhered to the inner surface of the concave portion, for example, as shown in FIG.
Nozzle 1 having one CO ₂ injection hole 15a
5 is the most efficient. The injection nozzle 15 in the illustrated example has four injection holes 15a for a pattern of four bands.
By uniformly injecting solid CO ₂ (which is liquid at the time of ejection as described above) from these ejection holes 15a, the concave portion forming the servo pattern 5 and its periphery can be reliably cleaned. .

Further, solid CO ₂ is blown from a CO ₂ spraying nozzle having a certain angle in a direction opposite to a magnetic tape running at a high speed (for example, 10 m / sec). Specifically, as shown in FIG. 2, FIG. 3 and FIG. 7, the solid CO ₂ sprayed portion (the portion hit by the solid CO ₂ ) B on the back coat layer surface when viewed from the running direction of the magnetic tape 1. On the front side, for example, 30 ° to 90 ° (preferably 30 ° to 6 °) with respect to the surface of the back coat layer 2
0 °) An injection nozzle 15 for spraying CO ₂ is arranged in an inclined state, and solid CO ₂ is injected from the spray nozzle 15 in a direction opposite to the traveling direction A of the magnetic tape 1 to spray the CO ₂ onto the sprayed portion B.
To burn off the combustion debris attached to the concave portion for the optical servo on the surface of the back coat layer and the periphery thereof. By doing so, the relative speed of blowing CO ₂ can be increased while maintaining the flow of CO ₂ to the concave portion for the optical servo, so that the cleaning effect can be enhanced.

In order to efficiently generate a servo pattern,
While running a magnetic tape wound several thousand meters or more in length, after forming a concave portion for optical servo on the surface of the back coat layer by laser irradiation, perform a cleaning process and a wiping process on the surface, and then again orderly A device that can be wound is effective. In the present invention, as shown in FIG. 7, a delivery mechanism 11 for delivering the wound magnetic tape 1 in a predetermined direction, and a laser on the surface of the back coat layer of the delivered magnetic tape 1 in the present invention. An optical servo track forming unit 12 that forms a concave portion for optical servo by irradiating light, a cleaning unit 13 that cleans the surface of the back coat layer after forming the concave portion, and a winding mechanism that winds the magnetic tape 1 after the cleaning. A CO ₂ spraying unit having an injection nozzle 15 for spraying solid CO ₂ on the optical servo recess formed by the laser beam irradiation and the periphery thereof, the suction nozzle 16 for sucking the recess and burnt residues near its for said optical servo blown away by blowing CO ₂ A suction portion which is provided, by following suction of the burnt residues e.g. tissue and a wiping portion 17 wipes the surface of the backcoat layer and the magnetic layer, using an optical servo track forming cleaning device of the magnetic tape. However, in such an apparatus, a tension loss exists in each of the CO ₂ spraying unit and the wiping unit in the optical servo track forming unit 12 and the cleaning unit 13, and an optimum tension to the tape (for example, 70 g to 20 g) is applied.
0 g). Therefore, it is preferable to provide a tension control unit for controlling the tension of the magnetic tape for each unit. Specifically, as will be described in an embodiment to be described later, the tension is insulated by the first to third suction rolls 22 to 24, and the values of the tension detectors 27 and 28 provided in each part are determined by the respective suction rolls 22. It is effective to use a device in which the magnetic tape 1 is allowed to travel while maintaining an optimum tension by performing feedback control on the rotating servomotor.

Next, a cleaning method using a raised body or the like will be described. As a result of examining a method for efficiently removing the combustion scum adhered to and inside the concave portion formed by laser irradiation for optical servo with a relatively simple device, the brush was raised while running the magnetic tape in the longitudinal direction. By a method including a step of contacting a flocked body, a woven cloth (preferably velvet) or a non-woven cloth having hair, it has been found that a single run of the magnetic tape has a great effect in removing combustion residues. . That is, according to the present invention, the magnetic tape can be moved at high speed (for example, about 10 m).
/ Sec), and cleaning the surface of the back coat layer by a method including a step of contacting a flocked body, a woven fabric (preferably velvet) or a non-woven fabric having raised hair on the surface of the back coat layer, This is to efficiently remove combustion debris (powder or the like) attached to and inside the optical servo concave portion present on the back coat layer surface.

In carrying out the above-mentioned method, according to the present invention, as shown in FIG.
Mechanism section 11 for sending the magnetic tape 1 in a predetermined direction, an optical servo track forming section 12 for irradiating the surface of the back coat layer 2 of the magnetic tape 1 with laser light to form a concave portion for optical servo, A cleaning unit 13 for cleaning the surface of the back coat layer after the formation,
The cleaning unit 13 has a winding mechanism 14 for winding the magnetic tape 1 after the cleaning, and the cleaning unit 13 includes a backing material, woven fabric, or nonwoven fabric having raised hairs for cleaning the surface of the back coat layer. A contact portion 15b for contacting the surface of the coat layer; and a wiping portion 17 for wiping off unnecessary powder adhering to the surface of the back coat layer.
And an optical servo track forming / cleaning device for a magnetic tape, wherein the device is disposed. This apparatus has a high productivity because the operation of forming the concave portion for the optical servo in the back coat layer of the magnetic tape and the operation of cleaning the combustion residue can be performed on one line. In this case, if an optical servo track forming unit, a tension control unit is provided for each of a contact unit and a wiping unit in the cleaning unit, and the tension of the magnetic tape is controlled for each unit by these tension control units, the production is improved. Performance can be improved.

According to the present invention, it is possible to efficiently remove the combustion residue existing on the concave portion on the surface of the back coat layer and the periphery thereof because the raised hair enters the concave portion and has an appropriate length and rigidity. It is considered that the combusted waste is efficiently scraped out of the concave portion by the entered hair.

The single fiber diameter of the raised hair is 0.5 μm.
10 μm, preferably 1 μm to 8 μm, more preferably 2 μm to 6 μm. A single fiber in this range is preferable because, when the single fiber diameter is less than 0.5 μm, the bristle stiffness (stiffness) is small, so the effect of scraping out the combustion residue is small, and when it exceeds 10 μm, the bristle does not easily enter the recess. It is because it becomes.

The hair length of the single fiber is preferably 0.5 mm to 5 mm, more preferably 1 mm to 4 mm, and still more preferably 1 mm to 3 mm. This range is preferable because if it is less than 0.5 mm, the bristle does not easily enter the concave portion, and if it exceeds 5 mm, the bristle stiffness (strength of the bristle) becomes small and the effect of scraping out the combustion waste becomes small. Further, as a means for obtaining a scraping effect while maintaining rigidity, a method of dividing a thick single fiber tip portion is also effective.

The brushed hair is made of natural fibers such as cotton and hemp,
At least one of synthetic fibers such as rayon and polyester is used. The fibers may be either single or mixed. The fibers may be single fibers or two or more fibers.

As a material for these raised hairs, it is preferable to include at least cotton because cotton has appropriate rigidity (lumbar strength) and thickness. For example, 30% to 7% cotton
A blend type of 0% rayon 70% to 30% can be used.

As described above with reference to FIG. 6, the powder generated by the laser irradiation adheres most to the inner surface of the concave portion of the servo pattern. Flocked body with brushed hairs,
The woven or non-woven fabric is made of a rotating drum 31 as shown in FIG.
The brushed cloth 32 may be wound around the magnetic tape, and the brushed cloth may be replaced every one winding of the long magnetic tape of several thousand meters, or the brushed cloth may be continuously supplied. However, the former method simplifies the apparatus. Therefore, the former method will be described below as an example.

As shown in FIG. 8, high speed (for example, 10 m /
At a constant contact angle of 90 ° to 140 ° on the surface of the back coat layer 2 of the magnetic tape 1 running at a constant speed (see FIG. 8).
As shown in FIG.
30) and a constant speed [30 to 30] in a direction opposite to the running direction of the magnetic tape 1.
The brushing drum 30 is rotated at 50 rpm (1800 to 3000 rpm)], and the input side tension is 50 to 100 g,
It is preferable to adjust the tape tension to 1.7 to 2.5 N by adjusting the output side tension to 170 to 260 g, since the effect of removing combustion scum increases.

The contact angle of 90 ° to 140 ° is preferable because if the contact angle is less than 90 °, it is necessary to reduce the feeding speed of the magnetic tape, and it takes a long time to remove combustion residues. This is because, when recording / reproducing is repeated, the combustion scabs fall out of the recesses and re-attach to the magnetic layer and the flat portion of the back coat layer, which tends to cause an increase in the error rate and a decrease in the S / N of the servo signal. On the other hand, when the angle exceeds 140 °, the arrangement of parts of the apparatus tends to be tight. Usually, 90 ° to 120 ° is more preferable.

The rotation speed of the raising drum is 188.4-31.
4 radians / second (1800-3000 rpm) is preferred. When the rotation speed is 188.4 radians / sec (1800 rpm)
If the rotation speed exceeds 314 radians / second (3000 rpm), the motor becomes expensive if the rotation speed exceeds 314 radians / second (3000 rpm). There is also a method of arranging two or more raised drums, but the apparatus becomes large.

To generate a servo pattern efficiently,
While running a magnetic tape wound several thousand meters or more in length, after forming a concave portion for optical servo on the surface of the back coat layer by laser irradiation, perform a cleaning process and a wiping process on the surface, and then again orderly A device that can be wound is effective. In the present invention, as shown in FIG. 9, a delivery mechanism 11 for delivering the wound magnetic tape 1 in a predetermined direction, and a laser on the surface of the back coat layer of the delivered magnetic tape 1 in the present invention. An optical servo track forming unit 12 that forms a concave portion for optical servo by irradiating light, a cleaning unit 13 that cleans the surface of the back coat layer after forming the concave portion, and winds the magnetic tape 1 into a pancake shape after the cleaning. A contact portion for bringing a flocking, woven or non-woven fabric having raised hairs into contact with the surface of the back coat layer in order to clean the surface of the back coat layer; 1
5b and a device for forming and cleaning optical servo tracks of a magnetic tape, wherein a wiping unit 17 for wiping unnecessary powder adhered to the surface of the back coat layer with, for example, a tissue is used. However, in such an apparatus, the optical servo track forming unit 12,
There is a tension loss in each of the contact portion 15b and the wiping portion 17 in the cleaning unit 13, and the tension may exceed the optimal tension (for example, 70 g to 200 g) with respect to the tape. Therefore, it is preferable to provide a tension control unit for controlling the tension of the magnetic tape for each unit. Specifically, as described in an embodiment described later, first to first
The tension is insulated by the third suction rolls 22 to 24, and the values of the tension detectors 27 and 28 provided in each part are determined by the respective suction rolls 22.
An apparatus is effective in which the magnetic tape 1 is caused to travel while maintaining an optimum tension with respect to the magnetic tape 1 by performing feedback control to a servo motor for rotating the magnetic tape 1 to 24.

Hereinafter, a preferred embodiment for each component will be described. <Nonmagnetic Support> The thickness of the nonmagnetic support is preferably 7.0 μm or less, more preferably 2.0 to 7.0 μm. A non-magnetic support having a thickness in this range is more preferable if the thickness is less than 2 μm, the film formation is difficult, and the tape strength is reduced.
If the thickness exceeds μm, the total thickness of the tape becomes large, and the storage capacity per one roll of the tape becomes small.

The Young's modulus of the non-magnetic support in the longitudinal direction varies depending on the thickness of the non-magnetic support, but is usually 5.07 GPa.
(500 kg / mm ² ) or more is used. When the thickness of the non-magnetic support is 5.0 μm or less, 10.13
Those having a Young's modulus of GPa (1000 kg / mm ² ) or more are preferably used. The nonmagnetic support having a Young's modulus in the above range is used because if it is less than 5.07 GPa (500 kg / mm ² ), the strength of the magnetic tape becomes weak or the running of the magnetic tape becomes unstable.

The Young's modulus of the non-magnetic support in the longitudinal direction is M
D, the ratio when the Young's modulus in the width direction is TD (MD / T
D) is preferably from 1.0 to 1.8, more preferably from 1.1 to 1.7. This range is preferable because the head touch is improved. Such a non-magnetic support includes a polyethylene terephthalate film, a polyethylene naphthalate film, an aromatic polyamide film, an aromatic polyimide film and the like.

<Undercoat layer> An undercoat layer may be provided between the nonmagnetic support and the magnetic layer. The thickness of the undercoat layer is 0.3 to 3.0μ
m is preferable, 0.3 to 2.5 μm is more preferable, and 0.3 to 2.5 μm is preferable.
2.0 μm is more preferred. This range is preferred because
If the thickness is less than 0.3 μm, the durability of the magnetic tape may be deteriorated. If the thickness exceeds 3.0 μm, the effect of improving the durability of the magnetic tape is not only saturated, but also the entire thickness of the tape is increased, and the tape length per roll is increased. This is because the storage capacity is reduced and the storage capacity is reduced.

The undercoat layer may contain carbon black (hereinafter also referred to as CB) for the purpose of improving conductivity, and non-magnetic particles for the purpose of controlling paint viscosity and tape rigidity.
The non-magnetic particles used in the undercoat layer include titanium oxide, iron oxide, and alumina, but iron oxide alone or a mixture of iron oxide and alumina is preferably used. The undercoat layer has a particle size of 10 to 1 based on the weight of all inorganic powders in the undercoat layer.
15 to 35% by weight of carbon black of 00 nm, 0.05 to 0.20 μm of major axis length, 35 to 83% by weight of nonmagnetic iron oxide having a minor axis length of 5 to 200 nm, and particle size of 10 to
When 100 nm alumina is contained in an amount of 0 to 20% by weight,
Wet-on-wet is preferable because the surface roughness of the magnetic layer formed thereon is reduced. As the nonmagnetic iron oxide, granular or amorphous nonmagnetic iron oxide may be used in addition to the needle shape. When granular or amorphous non-magnetic iron oxide is used, iron oxide having a particle size of 5 to 200 nm is preferable. In addition, 100 nm within a range that does not impair the smoothness of the surface.
It does not exclude the addition of the above-mentioned large particle size CB. In that case, the CB amount is preferably such that the sum of the small particle size CB and the large particle size CB is within the above range.

Carbon black (C) to be added to the undercoat layer
As B), acetylene black, furnace black, thermal black and the like can be used. Usually, the particle size is 5
nm to 200 nm is used.
00 nm is preferred. This range is preferred because
Because carbon black has a structure,
If the particle size is less than 10 nm, it is difficult to disperse CB,
If the thickness is 0 nm or more, the smoothness is deteriorated. The amount of CB added depends on the particle diameter of CB, but is preferably 15 to 35% by weight. This range is preferable because the effect of improving conductivity is poor when the content is less than 15% by weight, and the effect is saturated when the content exceeds 35% by weight. It is more preferable to use CB having a particle size of 15 nm to 80 nm by 15 to 35% by weight, and it is even more preferable to use CB having a particle size of 20 to 50 nm by 20 to 30% by weight. By adding carbon black having such a particle size and amount, electric resistance is reduced and running unevenness is reduced.

The nonmagnetic iron oxide to be added to the undercoat layer preferably has a major axis length of 0.05 to 0.20 μm and a minor axis length (particle size) of 5 to 200 nm in the case of a needle shape. In the case of an amorphous material, the particle size is preferably 5 to 200 nm. A particle size of 5 to 150 nm is more preferable, and a particle size of 5 to 100 nm.
Is more preferred. Needle-like ones are more preferable because the orientation of the magnetic layer is improved. The addition amount is preferably 35 to 83% by weight, more preferably 40 to 80% by weight. The particle size in this range (short axis length in the case of needles) is preferable because if the particle size is less than 5 nm, uniform dispersion is difficult, and if it exceeds 200 nm, unevenness at the interface between the undercoat layer and the magnetic layer increases. . The addition amount in this range is preferable because if less than 35% by weight, the effect of improving the coating film strength is small, and if it exceeds 83% by weight, the coating film strength is rather reduced.

The undercoat layer may contain alumina in addition to iron oxide. The particle size of alumina is preferably 10 to 100 nm, more preferably 20 to 100 nm, and 30 to 10 nm.
0 nm is more preferred. A particle size in this range is preferable because if the particle size is less than 10 nm, uniform dispersion is difficult and 100 n
If m exceeds m, unevenness at the interface between the undercoat layer and the magnetic layer increases. The addition amount of alumina is usually 0 to 20% by weight, but 2 to 10% by weight is more preferable.

<Lubricant> Lubricants having different roles can be used in the coating layer composed of the undercoat layer and the magnetic layer. When the undercoat layer contains 0.5 to 4.0% by weight of higher fatty acid and 0.2 to 3.0% by weight of higher fatty acid ester based on the whole powder, the magnetic tape and This is preferable because the coefficient of friction with the guide or the like of the traveling system is reduced. The reason for the addition of higher fatty acids in this range is that if it is less than 0.5% by weight, the effect of reducing the friction coefficient is small, and if it exceeds 4.0% by weight, the undercoat layer is plasticized and the toughness is lost. . Further, the addition of higher fatty acid esters in this range is preferably 0.
If it is less than 5% by weight, the effect of reducing the coefficient of friction is small, and if it exceeds 3.0% by weight, the amount of transfer to the magnetic layer is too large, and there are side effects such as sticking of the magnetic tape and the guide of the running system. is there. As fatty acids, higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid and linoleic acid are used. Examples of the fatty acid ester include butyl stearate, octyl stearate, amyl stearate,
Isooctyl stearate, octyl myristate, butoxyethyl stearate, sorbitan mono-stearate anhydride, sorbitan di-stearate, sorbitan tristearate and the like are used.

The magnetic layer contains 0.2 to 3.0% by weight of a fatty acid amide with respect to the ferromagnetic powder (eg, ferromagnetic metal powder), and 0.2 to 3.0% by weight of a higher fatty acid ester. Contains, magnetic tape and running system guide and MR
This is preferable because the coefficient of friction between the head and the slider or the like is reduced. When the fatty acid amide in this range is preferable, the friction coefficient (dynamic friction coefficient) of the head slider / magnetic layer tends to increase when the content is less than 0.2% by weight, and bleed out and drop out when the content exceeds 3.0% by weight. This is because a defect occurs. As the fatty acid amide, amides of the above higher fatty acids such as palmitic acid and stearic acid can be used. The addition of the higher fatty acid ester in the above range is preferable because the effect of reducing the coefficient of friction is small when the content is less than 0.2% by weight, and when the content exceeds 3.0% by weight, the magnetic tape and the guide of the traveling system stick. This is because there are side effects. Note that this does not exclude mutual movement between the lubricant of the magnetic layer and the lubricant of the undercoat layer. The coefficient of friction (μ _msl ) of the MR head with the slider is preferably 0.30 or less, more preferably 0.25 or less. This range is preferable because if it exceeds 0.30, spacing loss due to slider contamination is likely to occur. It should be noted that it is difficult to realize a value of less than 0.10. The coefficient of friction (μ _msus ) with SUS is preferably 0.10 to 0.25, more preferably 0.12 to 0.20. This range is preferable because if it is less than 0.10, it becomes slippery at the guide portion and the traveling becomes unstable, and if it exceeds 0.25, the guide is easily stained. Also, [(μ _msl ) / (μ
_msus )] is preferably from 0.7 to 1.3, more preferably from 0.8 to 1.2. This range is preferable because tracking deviation (off-track) due to meandering of the magnetic tape is reduced.

<Magnetic Layer> The thickness of the magnetic layer is as described above.
It is usually 0.3 μm or less, preferably 0.01 to 0.3 μm, more preferably 0.3 μm.
01 to 0.25 μm is more preferable, and 0.01 to 0.10 μm
Is more preferred. This range is more preferably 0.0
If the thickness is less than 1 μm, it is difficult to obtain a uniform magnetic layer. If the thickness exceeds 0.3 μm, the reproduction output becomes small due to thickness loss, or the product of the residual magnetic flux density and the thickness becomes too large. Is likely to occur. The coercive force of the magnetic layer is 120 to 320 kA / m
Is preferable, and 140 to 320 kA / m is more preferable.
This range is preferable because if the recording wavelength is shorter than 120 kA / m, the output will decrease due to demagnetizing field demagnetization.
If it exceeds 0 kA / m, it becomes difficult to perform recording with a magnetic head. The product (Brδ) of the residual magnetic flux density (Br) of the magnetic layer in the longitudinal direction of the tape and the magnetic layer thickness (δ) is
0.0018 μTm to 0.06 μTm is preferable, and 0.003 μTm is preferable.
6 to 0.050 Tm is more preferable. This range is preferable because, if it is less than 0.0018 μTm, the reproduction output by the MR head is small, and if it exceeds 0.06 μTm, the reproduction output by the MR head tends to be distorted. When the average surface roughness Ra of the magnetic layer is 3.2 nm or less and 1.0 nm or more, the center value of the unevenness of the magnetic layer is P ₀ , and the maximum protrusion amount of the magnetic layer is P ₁ (P ₁ − P ₀ ) is 30 nm or less and 10 nm or more,
(P ₁ −P ₂₀ ) when the _twentieth convex amount is P ₂₀ is 5
When the thickness is less than nm, the contact with the MR head is improved, and the reproduction output when the MR head is used is high.

As the magnetic powder added to the magnetic layer, ferromagnetic iron-based metal powder and hexagonal barium ferrite powder can be used. The coercive force of the ferromagnetic iron-based metal powder and the hexagonal barium ferrite powder is preferably 120 to 320 kA / m, and the saturation magnetization is 120
^{~200A · m 2 / kg (120~200emu} / g) are ^{preferable, 130~180A · m 2 / kg (} 130~18
0 emu / g) is more preferred. For hexagonal barium ferrite powder, 50 to 70 A · m ² / kg (50 to 70 e
mu / g) is preferred. Note that the magnetic properties of the magnetic layer and the magnetic properties of the ferromagnetic powder are measured values of an external magnetic field of 1.28 MA / m (16 kOe) using a sample vibrating magnetometer.

The average major axis length of the ferromagnetic iron-based metal powder is preferably from 0.03 to 0.2 μm, more preferably from 0.03 to 0.18 μm.
Is more preferable, and 0.03 to 0.10 μm is further preferable. This range is preferable because the average major axis length is 0.03 μm.
If the particle size is less than 0.2 μm, the cohesive force of the magnetic powder increases, and it is difficult to disperse the magnetic powder in the coating. In the hexagonal barium ferrite powder, the plate diameter is preferably 5 to 200 nm, and
100 nm is more preferred, and 10 to 50 nm is even more preferred. The average major axis length and the particle diameter are obtained by actually measuring the particle size from a photograph taken with a scanning electron microscope (SEM) and calculating the average value of 100 particles. The BET specific surface area of the ferromagnetic iron-based metal powder is 35
m is preferably not less than ² / g, more preferably at least 40 m ² / g, most preferably at least 50 m ² / g. The BET specific surface area of the hexagonal barium ferrite powder is 1 to 100 m ^2.
/ G is preferably used.

For the undercoat layer and the magnetic layer, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-acetic acid There is a combination of at least one selected from a vinyl-maleic anhydride copolymer, a vinyl chloride-hydroxyl group-containing alkyl acrylate copolymer, and nitrocellulose with a polyurethane resin. Among them, it is preferable to use a vinyl chloride-hydroxyl group-containing alkyl acrylate copolymer and a polyurethane resin in combination. Polyurethane resins include polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane,
Examples include polyester polycarbonate polyurethane.

COOH, SO ₃ M, OSO
₂ M, P = O (OM) ₃ , OP = O (OM) ₂ [wherein M represents a hydrogen atom, an alkali metal ion or an amine salt. ], OH, NR'R ", N + R '" R ""
R """whereR", R ", R"",R"",
R ′ ″ ″ independently represents hydrogen or a hydrocarbon group], and a binder such as a urethane resin made of a polymer having an epoxy group is used. The reason for using such a binder is to improve the dispersibility of the magnetic powder and the like as described above. When used in combination of two or more resins are preferably match the polarity of the functional groups, among them the combination of each other -SO ₃ M group.

These binders are used in an amount of 7 to 50 parts by weight, preferably 10 to 35 parts by weight, based on 100 parts by weight of the ferromagnetic powder. Particularly, as a binder, 5 to 30 parts by weight of a vinyl chloride resin and 2-2 to a polyurethane resin
It is most preferable to use 0 parts by weight in combination.

It is desirable to use together with these binders a thermosetting crosslinking agent that bonds to a functional group or the like contained in the binder to form a crosslink. Examples of the crosslinking agent include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like, reaction products of these isocyanates with those having a plurality of hydroxyl groups such as trimethylolpropane, and condensation products of the above isocyanates. Various polyisocyanates are preferred. These crosslinking agents are generally used in a proportion of 10 to 50 parts by weight based on 100 parts by weight of the binder. More preferably, it is 10 to 35 parts by weight. The amount of the cross-linking agent used for the magnetic layer is about 1/2 (3
(0% to 60%) is preferable because the coefficient of friction of the MR head with respect to the slider is reduced. This range is preferable because if it is less than 30%, the coating strength of the magnetic layer tends to be weak, and if it exceeds 60%, the conditions for wiping with a tissue (LRT processing conditions) must be increased in order to reduce the coefficient of friction on the slider. It is necessary to do so, leading to an increase in cost.

Conventionally known CB is added for the purpose of improving conductivity and surface lubricity. As these CBs, acetylene black, furnace black, thermal black and the like can be used. Particles having a particle size of 5 nm to 200 nm are used, and particles having a particle size of 10 nm to 100 nm are preferable. This range is preferable because it is difficult to disperse CB when the particle size is 5 nm or less, and a large amount of C
This is because B must be added, and in any case, the surface becomes rough, which causes a decrease in output. The addition amount is preferably 0.2 to 5% by weight with respect to the ferromagnetic powder,
% Is more preferred. This range is preferably 0.2
If the content is less than 5% by weight, the effect is small, and if more than 5% by weight of CB is added, the surface of the magnetic layer tends to be rough.

<Backcoat Layer> The thickness of the backcoat layer is preferably from 0.25 to 0.8 μm, more preferably from 0.4 to 0.8 μm, even more preferably from 0.4 to 0.6 μm. This range is good because if it is less than 0.25 μm, it is difficult to control the conditions (laser power, etc.) for forming the concave portion for optical servo, and if it exceeds 0.8 μm, the total thickness of the tape becomes thick, and This is because the storage capacity of the device becomes small.

The coefficient of friction between the back coat layer and SUS (μ
_Bsus ) is preferably from 0.10 to 0.30, more preferably from 0.10 to 0.25. This range is preferable because when it is less than 0.10, it becomes slippery at the guide portion and the traveling becomes unstable,
If it exceeds 30, the guide is apt to become dirty. [( _ΜmSL ) / ( _μBsus )] is preferably 0.8 to 1.5, and more preferably 0.9 to 1.4. This range is preferable because tracking deviation (off-track) due to meandering of the magnetic tape is reduced.

The average value of the light reflectance of the flat portion of the back coat layer is preferably 8.5% or more, more preferably 9.0% or more, and even more preferably 10% or more. The average value of the light reflectance is
8.5% or more is preferable because if it is less than 8.5%, the servo signal (S) becomes small and causes tracking failure. The upper limit of the average value of the light reflectance of the ordinary practical back coat layer is 15%. If the average value of the light reflectance of the back coat layer exceeds 15%, the durability may generally be deteriorated with a uniform back coat layer. For this reason,
When using a back coat layer having an average value of the light reflectance exceeding 15%, the average value of the light reflectance of the flat portion other than the portion where the concave portion for the optical servo is formed is set to 15% or less. It is necessary to prevent the durability from deteriorating.

The average value of the light reflectance is set to 8.5% or more, and the variation rate of the light reflectance of the flat portion (the position of the magnetic tape) [(the variation of the light reflectance variation from the average value of the light reflectance). (Maximum value of absolute value) ÷ (average value of light reflectance) × 100] = 10
%, Preferably 5% or less, more preferably 3% or less, and most preferably 0%.
It is. This range is preferable because if it exceeds 10%, the S / N of the servo signal becomes small, causing a tracking error. In order to evaluate the variation of the light reflectance depending on the location, it is sufficient to examine the variation of the light reflectance per 40 mm in length. This is because the change in light reflectance per 40 mm length is almost equal to the change in light reflectivity per full length of the magnetic tape.

The average value of the light reflectance of the flat portion is set to 8.5% or more, and the variation rate of the light reflectance of the flat portion depending on the location is 1%.
A preferred method for reducing the content to 0% or less is to set the content of the nonmagnetic powder in the back coat layer [(weight of nonmagnetic powder) / (weight of nonmagnetic powder + weight of binder) × 100] to 50% by weight or more. In addition, there is a method in which the surface roughness Ra of the flat portion of the back coat layer measured by the AFM method is controlled to 30 nm or less, and the half width of the variation of the surface roughness Ra depending on the magnetic tape position is controlled to 5 nm or less. The surface roughness Ra of the flat portion is usually 10
nm or more is preferable, and 20 nm or more is more preferable. The reason why the surface roughness Ra of the flat portion is preferably set to 10 nm or more is that if Ra is less than 10 nm, the durability tends to deteriorate. When using a back coat layer having a flat portion having a surface roughness Ra of less than 10 nm, the flat portion has a surface roughness Ra other than the portion where the concave portion for optical servo is formed.
Needs to be 10 nm or more. In addition, 40 μm × 4
If the surface roughness Ra per 0 μm is measured by AFM at 100 points, almost the same results as those obtained by measuring Ra and Ra variation per the entire length of the magnetic tape can be obtained. Therefore, the evaluation can be performed by the former measured value. . As described above, the light reflectance of the flat portion of the back coat layer increases when the content of the nonmagnetic powder is 50% by weight or more and the surface is smooth.
When the content of the nonmagnetic powder in the back coat layer is 60% by weight or more, not only is it difficult to reduce the surface roughness Ra of the flat portion to 30 nm or less, but also the calendar condition is increased to increase the roughness Ra of the flat portion to 30 nm or less. In this case, the durability of the back coat layer tends to deteriorate. For this reason, the content of the nonmagnetic powder in the back coat layer is practically 50 to 60% by weight.
Is preferable, and 50 to 58% by weight is more preferable.
50 to 56% by weight is more preferable, and 53 to 56% by weight.
Is even more preferred.

When the proportion of carbon black in the non-magnetic powder is 80% by weight or more, it is preferable to form a concave portion for optical servo by laser light, and it is more preferable to be 85% by weight or more. Furthermore, it is preferable to add a total of 20% by weight or less of iron oxide (for example, red iron oxide) together with carbon black because the strength of the back coat layer is increased.

The carbon black (C
As B), acetylene black, furnace black, thermal black and the like can be used. Usually, small particle size carbon and large particle size carbon are used. As the small-diameter carbon, one having a particle diameter of 5 nm to 200 nm is used, and one having a particle diameter of 10 nm to 100 nm is more preferable.
This range is more preferable because it is difficult to disperse CB when the particle diameter is 10 nm or less, and it is necessary to add a large amount of CB when the particle diameter is 100 nm or more, and in any case, the surface roughness Ra is 30 nm or more. And the light reflectance of the flat portion is reduced. As the large-diameter carbon, 5 to 5 of the total carbon (total of the small-diameter carbon and the large-diameter carbon)
When 15% by weight and a large particle size carbon having a particle size of 200 to 400 nm are used, the surface is not roughened, and the effect of improving the running property is increased. The amount in this range is preferable because if it is less than 5% by weight, the effect of improving the durability is small, and if it exceeds 15% by weight, the fluctuation of the light reflectance of the flat portion becomes large. The added amount of the small particle size carbon and the large particle size carbon is preferably 80 to 100% by weight, and more preferably 85 to 100% by weight based on the weight of the nonmagnetic powder.
100% by weight is more preferred. The surface roughness Ra measured by AFM is preferably 30 nm or less as described above.
0 nm or more.

In the back coat layer, for the purpose of improving the strength,
Iron oxide or the like (for example, an additive usually added to the back coat layer, such as iron oxide or alumina) is added in an amount of 20% by weight or less based on the weight of the inorganic powder. The addition amount is more preferably 2 to 20% by weight, and still more preferably 5 to 15% by weight. This range is more preferable because if it is less than 2% by weight, the strength improving effect is small, and if it exceeds 20% by weight, it becomes difficult to form a concave portion for optical servo by laser. An oxide containing iron oxide as a main component is preferably used. However, when iron oxide and alumina are simultaneously added, the amount of alumina added is preferably 20% by weight or less of the iron oxide. The reason why 20% by weight is preferable is that if the amount of added alumina exceeds 20% by weight of iron oxide, it is necessary to increase the cleaning conditions for removing combustion residues. Particle size of iron oxide (granular) is 0.05μm ~ 0.4μ
m is preferable, and 0.07 μm to 0.35 μm is more preferable. This range is preferable because the effect of improving the strength is small when the thickness is less than 0.05 μm, and the change in the reflectance of the flat portion becomes large when the thickness exceeds 0.4 μm.

As the binder, the same resin as that used for the magnetic layer and the undercoat layer described above can be used for the back coat layer. Among them, a cellulose-based resin is used in order to reduce the friction coefficient and improve the running property. It is preferable to use a resin and a polyurethane resin in combination. The content of the binder is usually 40 to 150 parts by weight based on 100 parts by weight of the total of carbon black and the inorganic nonmagnetic powder, and 50 to 1 part by weight.
It is preferably 20 parts by weight, more preferably 50 to 110 parts by weight, even more preferably 50 to 100 parts by weight. This range is preferred because if the amount is less than 50 parts by weight, the strength of the backcoat layer tends to be insufficient, and if it exceeds 120 parts by weight, the coefficient of friction tends to increase. 30 to 70 parts by weight of a cellulose resin and 20 to 5 parts of a polyurethane resin
It is preferable to use 0 parts by weight. Further, in order to further cure the binder, it is preferable to use a crosslinking agent such as a polyisocyanate compound.

The crosslinking agent used for the magnetic layer and the undercoat layer described above is used as the crosslinking agent in the back coat layer. The amount of the crosslinking agent is usually used in a ratio of 10 to 50 parts by weight based on 100 parts by weight of the binder. Preferably it is 10 to 35 parts by weight, more preferably 10 to 30 parts by weight. This range is preferable because when the amount is less than 10 parts by weight, the coating strength of the back coat layer tends to be weak, and when the amount exceeds 35 parts by weight, S
This is because the dynamic friction coefficient with respect to US increases.

<LRT treatment (wrapping / rotary /
Tissue treatment)> Regarding the magnetic layer, it is possible to optimize the surface smoothness, the coefficient of friction with the slider material or cylinder material of the MR head, the surface roughness, and the surface shape by performing the LRT process as described below. As a result, the running property of the magnetic tape, the spacing loss can be reduced, and the MR reproduction output can be improved.

(1) Wrapping treatment: A polishing tape (lapping tape) is rotated by a rotating roll at a constant speed (standard: 1) in the direction opposite to the tape feeding (standard: 400 m / min).
(4.4 cm / min) and brought into contact with the surface of the tape magnetic layer by pressing the guide block from above. At this time, the tension of unwinding the magnetic tape and the tension of the wrapping tape were constant (standard: 100 g each, 250 g each).
Polishing is performed as g). The polishing tape (wrapping tape) 3 used in this step is, for example, M20000
No. WA10000 or No. K10000 is a polishing tape (lapping tape) with fine abrasive grains. The use of a grinding wheel (wrapping wheel) instead of or in combination with a grinding tape (wrapping tape) is not excluded, but if frequent replacement is required, use only the grinding tape (wrapping tape). I do.

(2) Rotary treatment: grooved wheel for air release [Standard: 1 inch (25.4 mm) wide, 60 mm in diameter,
Air vent groove 2 mm width, groove angle 45 degrees, manufactured by Kyowa Seiko Co., Ltd.] and the magnetic layer at a constant contact angle (standard: 90 degrees) in the opposite direction to the tape at a constant rotational speed (usually: 200 to 3).
000 rpm, standard: 1100 rpm).

(3) Tissue treatment: A tissue (for example, a woven fabric Toraysee made by Toray Industries, Inc.) is rotated at a constant speed (standard: 14.0 mm / min.) In the direction opposite to the tape feed on the back coat layer and the magnetic layer surface with a rotating rod. ) To perform the cleaning process.

The cassette tape incorporating the magnetic tape of the present invention has a high S / N of the optical servo signal, and therefore has excellent servo tracking performance and is highly reliable as a backup tape for a hard disk drive.

[0074]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these. In addition, the part of an Example and a comparative example shows a weight part.

Example 1 << Coating Component for Undercoat Layer >> (1) Iron oxide powder (particle size: 0.11 × 0.02 μm) 68 parts α-alumina (particle size: 0.07 μm) 8 parts Carbon Black (particle size: 25 nm, oil absorption: 55 g / cc) 24 parts Stearic acid 2.0 parts Vinyl chloride-hydroxypropyl acrylate copolymer 8.8 parts (contained -SO ₃ Na group: 0.7 × 10 ^-4) (Equivalent / g) Polyester polyurethane resin 4.4 parts (Tg: 40 ° C., containing-SO ₃ Na group: 1 × 10 ⁻⁴ equivalent / g) Cyclohexanone 25 parts Methyl ethyl ketone 40 parts Toluene 10 parts (2) Butyl stearate 1 part Cyclohexanone 70 parts Methyl ethyl ketone 50 parts Toluene 20 parts (3) Polyisocyanate (Nippon Polyurethane Industry Co., Ltd. Coronate L) 4.4 parts Cyclohexanone 10 parts Methyl ethyl Ton 15 parts 10 parts of toluene

<< Coating Component for Magnetic Layer >> (A) 100 parts of ferromagnetic iron-based metal powder (Co / Fe: 30 at%, Y / (Fe + Co): 3 at%, Al / (Fe + Co): 5 wt%, Ca / Fe: 0, σs: 155 A · m ² / kg, Hc: 188.2 kA / m, pH: 9.4, major axis length: 0.10 μm) 12.3 parts of vinyl chloride-hydroxypropyl acrylate copolymer (contained —SO ₃ Na group: 0.7 × 10 ⁻⁴ equivalents / g) Polyester polyurethane resin 5.5 parts (contained —SO ₃ Na group: 1.0 × 10 ⁻⁴ equivalents / g) α-alumina (average particle size) 8 parts α-alumina (average particle diameter: 0.07 μm) 2 parts Carbon black 1.0 part (average particle diameter: 75 nm, DBP oil absorption: 72 cc / 100 g) Methyl acid phosphate 2 parts Palmitic acid amide 1.5 parts n-butyl stearate 1.0 Part 65 parts tetrahydrofuran 245 parts methyl ethyl ketone 85 parts toluene 85 parts (B) polyisocyanate (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.) 2.0 parts Cyclohexanone 167 parts

After kneading the component (1) in the above undercoat layer coating component with a kneader, the component (2) is added, and the mixture is stirred and subjected to a dispersion treatment with a sand mill having a residence time of 60 minutes. After the component (3) was added and the mixture was stirred and filtered, a paint for an undercoat layer was obtained. Separately, the above-mentioned magnetic layer coating component (A) is kneaded with a kneader, dispersed by a sand mill with a residence time of 45 minutes, and the magnetic layer coating component (B) is added thereto, followed by stirring and filtration. It was a magnetic paint. After drying and calendering the above undercoat paint on a non-magnetic support made of polyethylene naphthalate film (thickness: 6.2 μm, MD = 6.08 Pa, MD / TD = 1.1, manufactured by Teijin) Is applied so as to have a thickness of 1.8 μm, and on this undercoat layer,
Further, the above magnetic paint is applied with a magnetic field orientation treatment, drying, wet-on-wet so that the thickness of the magnetic layer after calendering treatment is 0.15 μm, and after the magnetic field orientation treatment, dried using a dryer, A magnetic sheet was obtained. The magnetic field orientation treatment was performed by installing an N-N counter magnet (5 kG) before the dryer, and in the dryer, 75 cm in front of the finger corrosion drying position of the coating film.
And two NN counter magnets (5 kG) were installed at intervals of 50 cm. The coating speed was 100 m / min.

<< Coating Component for Backcoat Layer >> 78 parts (41.5% by weight) of carbon black (particle diameter: 25 nm) 10 parts (5.3% by weight) of carbon black (particle diameter: 350 nm) [Total of carbon black 88 Part (46.8 parts by weight)] Bengala A (granularity: 0.1 μm) 10 parts (5.3% by weight) Bengala B (particle size: 0.27 μm) 2 parts (1.1% by weight) [Nonmagnetic powder total 100 parts (53.2 parts by weight)] nitrocellulose (NC) 44 parts (23.4% by weight) polyurethane resin (-SO ₃ Na group-containing) 31 parts (16.4 wt%) cyclohexanone 260 parts toluene 260 parts 525 parts of methyl ethyl ketone

After the above-mentioned coating composition for the back coat layer was dispersed in a sand mill with a residence time of 45 minutes, 13 parts (6.9% by weight) of polyisocyanate was added to prepare the coating composition for the back coat layer, followed by filtration. On the opposite side of the magnetic layer of the manufactured magnetic sheet, the magnetic sheet was dried so as to have a thickness of 0.5 μm after calendering, and dried. The magnetic sheet obtained in this way was heated at a temperature of 10 with a seven-stage calendar composed of metal rolls.
At 0 ° C., at a linear pressure of 147 kN / m (150 kgf / cm), the surface is mirror-finished, and the magnetic sheet is wound around a core at 70 ° C.
After aging for 72 hours, the substrate was cut into half widths and subjected to LRT processing under the following conditions. Then, using the optical servo track forming / cleaning apparatus shown in FIG. 7, a concave portion for optical servo was formed in the back coat layer. Then, a spraying process of solid CO ₂ and a cleaning process were performed. The magnetic tape thus obtained was assembled in a cartridge to produce a computer tape. The optical servo track forming / cleaning apparatus and processing using this apparatus will be described later.

<LRT (Lapping / Rotary / Tissue) Processing> (1) Lapping Processing: A polishing tape (lapping tape) is fed by a rotating roll (400 m / l).
The tape is moved at a speed of 14.4 cm / min in a direction opposite to that of the tape magnetic layer, and is pressed by the guide block 4 from above to make contact with the surface of the tape magnetic layer. At this time, the polishing treatment was performed with the magnetic tape unwinding tension set at 100 g and the wrapping tape tension set at 250 g. (2) Rotary aluminum wheel processing: width 1 inch (2
5.4 mm), a 60 mm diameter wheel with a 2 mm width grooved air vent (45 ° groove angle, manufactured by Kyowa Seiko Co., Ltd.) and the magnetic layer at a contact angle of 90 ° and a rotation speed of 1 in the opposite direction to the tape
The treatment was performed by contacting at 100 rpm. (3) Tissue treatment: A cleaning treatment was carried out by feeding a woven cloth tray made by Toray Industries Co., Ltd. with a rotating rod on the back layer and the magnetic layer surface at a speed of 14.0 mm / min in the direction opposite to the tape feeding.

Here, the above-described optical servo track forming / cleaning apparatus and processing using this apparatus will be described.

As shown in FIG. 7, the optical servo track forming / cleaning apparatus includes a delivery mechanism 11 for delivering the wound magnetic tape 1 in a predetermined direction, and a surface of the back coat layer of the delivered magnetic tape 1. Servo track forming section 12 for irradiating a laser beam on the surface to form an optical servo concave section, cleaning section 13 for cleaning the surface of the back coat layer after the concave section is formed, and winding up magnetic tape 1 after this cleaning. And a take-out mechanism 14.

The cleaning unit 13 has the laser light
For optical servo formed by irradiation of
Solid CO around_Two Equipped with an injection nozzle 15 for spraying
CO _Two Spraying part and this solid CO_Two By spraying
The blown-out optical servo recess and its periphery
Equipped with a suction nozzle (suction means) 16 for sucking the combustion waste
And the back coat layer after suction of the combustion waste
Wiping part 1 for wiping the surface of the body with a tissue cleaner
7 are arranged.

Of these, as shown in FIG. 3, the injection nozzle 15 provided in the CO ₂ spraying portion is provided with a CO ₂ injection hole 15a that matches the arrangement pattern of the concave portions for the optical servo in the width direction of the magnetic tape 1. And is set to be inclined by 30 ° with respect to the surface of the back coat layer 2 of the magnetic tape 1 (see FIG. 3). Then, solid CO ₂ is sprayed onto the sprayed portion B from an oblique upper front direction of the sprayed portion B of CO ₂ in the back coat layer 2 in a direction opposite to the running direction of the magnetic tape 1. . The suction nozzle 16 provided in the suction unit has a suction port 16a disposed near the sprayed portion B, and sucks combustion scum separated from the surface of the back coat layer by spraying solid CO _2. 16a to remove by suction.

On the other hand, the wiping portion 17 is provided with tissue cleaners 18 and 19 arranged so as to come into contact with the respective surfaces of the magnetic layer and the back coat layer of the magnetic tape 1 and the tissue cleaners 18 and 19 at a predetermined speed. And a pair of rollers 20 and 21 which are held so as to be able to be wound. Then, the tissue cleaners 18 and 19 are pressed against the respective surfaces of the magnetic layer and the back coat layer of the magnetic tape 1 to wipe off unnecessary powders adhering thereto.

In addition, the apparatus shown in FIG. 7 is provided with the following means to constitute the tension control means according to the present invention. That is, the first suction roll 22 is provided between the optical servo track forming unit 12 and the suction nozzle 16, the second suction roll 23 is provided between the ejection nozzle 15 and the wiping unit 17, and the wiping unit 17 and the winding mechanism are provided. The third suction rolls 24 are arranged between the first and second portions 14. Further, tension arms 25 and 26 for adjusting the tension of the magnetic tape 1 are provided between the feeding mechanism unit 11 and the optical servo track forming unit 12 and between the third suction roll 24 and the winding mechanism unit 14, respectively. Tension detectors 27 and 28 are provided between the second suction roll 23 and the ejection nozzle 15 and the wiping unit 17 for detecting the tension of the magnetic tape 1 and adjusting the tension. . Then, the tension of the magnetic tape 1 is insulated by the suction rolls 22 to 24, and the values of the tension detectors 27 and 28 are fed back to the servo motors that rotate the suction rolls 22 to 24, so that the optical servo track is provided. C in the forming unit 12 and the cleaning unit 13
Each part of the O ₂ spraying part and the wiping part 17 is configured so that an optimum tension to the magnetic tape can be obtained.

In the embodiment of the present invention, such a device is used to keep the magnetic tape tension at 150 g while maintaining the tension of the magnetic tape at 150 g.
The magnetic tape was run at a speed of m / sec to form a concave pattern for optical servo as described below, spraying solid CO ₂ , and cleaning combustion residues.

<Formation of Optical Servo Concave Pattern> FIG. 7
The surface of the back coat layer of the magnetic tape 1 was irradiated with laser light in the optical servo track forming section 12 of the optical servo track forming / cleaning apparatus shown in (1) to form a concave portion for optical servo. At this time, as shown in FIG. 6, the concave pattern for the optical servo is formed so that four bands are arranged in the width direction of the tape of 12.64 mm, and the optical band is formed so that the width of one band is about 0.4 mm. A concave group for servo was formed.

<Solid CO ₂ Spraying Process> Next, the spray nozzle 15 for spraying the solid CO ₂ and the suction nozzle 1
By using No. 6, the combustion scum generated by the laser light irradiation was substantially removed. Note that the angle of the injection nozzle 15 with respect to the backcoat layer surface was set to 30 ° as described above.

<Cleaning Process> Finally, using a tissue cleaner 18 provided in the wiping unit 17, the remaining combustion scum is completely removed, and Brδ (residual magnetic flux density and thickness of the magnetic layer in the longitudinal direction of the tape) is obtained. Product) is 0.
The above magnetic tape having 045 μTm and coercive force Hc of 192 kA / m was produced.

[Embodiment 2] A calendar condition was set to a temperature of 100
A magnetic tape was produced in the same manner as in Example 1, except that the temperature was changed from 90 ° C. and a linear pressure of 294 kN / m (300 kgf / cm) from a linear pressure of 147 kN / m (150 kgf / cm).

[Embodiment 3] A calendar condition was set to a temperature of 100
A magnetic tape was produced in the same manner as in Example 1 except that the temperature was changed from 147 kN / m (150 kgf / cm) at a linear pressure of 147 kN / m (300 kgf / cm).

Example 4 The thickness of the back coat layer was 0.5
A magnetic tape was produced in the same manner as in Example 1, except that the thickness was changed from 0.4 μm to 0.4 μm.

Example 5 The thickness of the back coat layer was 0.5
A magnetic tape was produced in the same manner as in Example 1 except that the thickness was changed from 0.6 μm to 0.6 μm.

Example 6 Using a non-magnetic support of 4.0 μm, the thickness of the undercoat layer was 1.0 μm and the thickness of the magnetic layer was 0.1 μm.
m, the total thickness was 5.7 μm in the same manner as in Example 1 except that the thickness of the back coat layer was changed from 0.5 μm to 0.6 μm.
m, Brδ is 0.030 μTm, coercive force Hc is 192 kA
/ M of magnetic tape.

Examples 7 to 10 A magnetic tape was produced in the same manner as in Example 1 except that the backcoat layer having the composition shown in Table 1 was used.

Reference Example 1 A magnetic tape was produced in the same manner as in Example 1, except that no solid CO ₂ spraying treatment was performed.

Comparative Examples 1 to 6 Magnetic tapes were prepared in the same manner as in Example 1 except that the backcoat layer having the composition and thickness shown in Table 2 was used.

Comparative Example 7 A non-magnetic support having a thickness of 4.0 μm was used, and the thickness of the undercoat layer was 1.0 μm and the thickness of the magnetic layer was 0.1 μm.
m, the total thickness was 5.7 μm in the same manner as in Comparative Example 3 except that the thickness of the back coat layer was changed from 0.5 μm to 0.6 μm.
m of magnetic tape was produced.

[0100]

[Table 1]

[0101]

[Table 2]

[Embodiment 11] Using the optical servo track forming / cleaning apparatus shown in FIG. 9, a concave portion for optical servo was formed in the back coat layer. A computer tape was produced in the same manner as in Example 1 except that the cleaning treatment was performed.

Here, the optical servo track forming / cleaning apparatus shown in FIG. 9 and the processing using this apparatus will be described.

As shown in FIG. 9, the optical servo track forming / cleaning apparatus used in this embodiment includes a feeding mechanism 11 for feeding the wound magnetic tape 1 in a predetermined direction, and a feeding mechanism 11 for feeding the fed magnetic tape 1. An optical servo track forming unit 12 for irradiating a laser beam on the surface of the back coat layer to form a concave portion for optical servo; a cleaning unit 13 for cleaning the surface of the back coat layer after forming the concave portion; And a take-up mechanism section 14 for taking up the roll 1.

The cleaning section 13 includes a contact section 15b for contacting a surface of the back coat layer with a brushed cloth, such as a flocked body, woven cloth or non-woven cloth, having brushed hair, for cleaning the surface of the back coat layer. And a wiping portion 17 for wiping the surfaces of the back coat layer and the magnetic layer with a tissue cleaner.

The raised portion drum 30 as shown in FIG. 8 is provided at the contact portion 15b. This brushed drum 30
Is a rotating drum (a drum having a diameter of 100 mm in this embodiment) rotating in a direction opposite to the running direction of the magnetic tape 1.
The brushed cloth 32 is wound around the peripheral surface of No. 1. A pair of guide rollers 41 are provided before and after the raising drum 30 for bringing the raising drum 30 into contact with the surface of the back coat layer of the magnetic tape 1 in a predetermined state.

On the other hand, the wiping unit 17 includes tissue cleaners 18 and 19 arranged so as to be in contact with the respective surfaces of the magnetic layer of the magnetic tape 1 and the back coat layer 2.
It has a pair of rollers 20 and 21 for holding the tissue cleaners 18 and 19 so that they can be wound up at a predetermined speed. Then, the tissue cleaners 18 and 19 are pressed against the magnetic layer of the magnetic tape 1 and the respective surfaces of the back coat layer 2 to wipe off unnecessary powders adhering thereto.

In addition, the apparatus shown in FIG. 9 is provided with the following means to constitute the tension control means in the apparatus of the present invention. That is, the first suction roll 22 is provided between the optical servo track forming section 12 and the contact section 15b, the second suction roll 23 is provided between the contact section 15b and the wiping section 17, and the wiping section 17 and the winding mechanism are provided. The third suction rolls 24 are arranged between the first and second portions 14. Further, tension arms 25 and 26 for adjusting the tension of the magnetic tape 1 are provided between the feeding mechanism unit 11 and the optical servo track forming unit 12 and between the third suction roll 24 and the winding mechanism unit 14, respectively. And the second suction roll 23, the contact portion 15b and the wiping portion 1
7, tension detectors 27 and 28 are provided to detect the tension of the magnetic tape 1 and to adjust the tension. The tension of the magnetic tape 1 is insulated by the suction rolls 22 to 24 and the tension detector 2
By feeding back the values of 7 and 28 to the servomotors that rotate the suction rolls 22 to 24, the optical tape track forming unit 12, the contact unit 15 b in the cleaning unit 13, and the wiping unit 17 are separated from each other with respect to the magnetic tape 1. It is configured to obtain an optimum tension.

In the embodiment of the present invention, by using such an apparatus, 10 m / m
The magnetic tape is run at a speed of 2 seconds to form a concave pattern for optical servo as described below, a contact processing by the raising drum 30, and tissue cleaners 18 and 19.
Was performed.

<Formation of Optical Servo Concave Pattern> FIG. 9
In the optical servo track forming unit 12 of the optical servo track forming / cleaning apparatus shown in (1), a laser beam is applied to the surface of the back coat layer 2 of the magnetic tape 1 to form a concave portion for optical servo so as to have a predetermined servo pattern. did. At this time, as the concave pattern for the optical servo,
As shown in FIG. 6, four bands were formed so as to be arranged in the width direction of the tape of 12.64 mm, and concave portions for optical servo were formed so that the width of one band was about 0.4 mm.

<Contact Processing by Raising Drum> Next, as shown in FIG. 8, the raising drum 30 is moved in the contact portion 15b in a direction opposite to the running direction of the magnetic tape by 314 radians / mm.
By rotating the magnetic tape 1 at a rotation speed of 3000 rpm to bring the surface of the back coat layer 2 of the magnetic tape 1 into contact with the raised cloth 32 mounted on the outer periphery of the raised drum 30 while applying a tension of 2.0 N, the servo pattern is formed. Burning scum was substantially removed from inside and around the concave portion of the back coat layer generated by laser baking during the formation. The brushed cloth 32 in the brushed drum 30 has a single fiber diameter of 4 μm.
A velvet planted with 2.5 mm long fibers obtained by twisting four pieces of cotton was used. At this time, the input side tension is 86 g, the output side tension is 208 g, and the raising drum 30
The contact angle between the magnetic tape 1 and the magnetic tape 1 was 120 °.

<Cleaning Process> Finally, using the tissue cleaners 18 and 19 provided in the wiping unit 17,
The residual combustion residue is completely removed, and Brδ is reduced to 0.0.
The above magnetic tape having 45 μTm and coercive force Hc of 192 kA / m was produced. The average reflectance of this magnetic tape is
9.0%, fluctuation rate is 3.0%, AFM surface roughness Ra is 25.1
The half value width of nm and Ra is 3.3 nm, and the S / N of the servo signal of Example 11 is 1.5 when the S / N of Reference Example 2 is 0 dB.
dB (6.1 d when the S / N of Comparative Example 1 is 0 dB)
B).

Example 12 Example 1 was performed except that the contact angle between the magnetic tape 1 and the raising drum 30 was 90 °.
A magnetic tape was prepared and processed in the same manner as in No. 1.

Example 13 A magnetic tape was treated in the same manner as in Example 11 except that the rotation speed of the raising drum 30 was set to 188.4 radians / second (1800 rpm). In addition, the input side tension at the time of the contact processing (processing at the contact portion) was 95 g, and the output side tension was 188 g.

Example 14 A magnetic tape was prepared and processed in the same manner as in Example 11, except that the tape tension used when performing the contact treatment with the raising drum was 1.8 N. In addition, the entry side tension at the time of contact processing is 80
g, and the output side tension was 188 g.

Example 15 A non-magnetic support having a thickness of 4.0 μm was used. The thickness of the undercoat layer was 1.0 μm and the thickness of the magnetic layer was 0.1.
μm, except that the thickness of the back coat layer was changed from 0.5 μm to 0.6 μm.
7 μm, Brδ is 0.030 μTm, coercive force Hc is 192
Preparation and processing of a magnetic tape having a kA / m were performed.

[Examples 16 to 19] Using a flocked body, woven fabric or non-woven fabric having raised hairs as shown in Table 3 as a raised cloth, and the number of raised brushes as shown in Table 3 A magnetic tape was prepared and processed in the same manner as in Example 11, except for the following.

Reference Example 2 A magnetic tape was prepared and processed in the same manner as in Example 11, except that the contact treatment by the raising drum 30 was not performed. The reflectivity of the back coat layer of this magnetic tape was 8.5%, the variation was 4.0%,
The FM surface roughness Ra is 25.2 nm, and the half width of Ra is 4.5 n.
m.

[0119]

[Table 3]

The measurement and evaluation were performed as follows. <Reflectance> The reflectance of the flat portion of the magnetic tape at an incident angle of 20 degrees and a reflection angle of 20 degrees was evaluated using a spectrometer manufactured by Unisoff Corporation. An LED having a wavelength of 880 nm was used as an incident light source. The spot diameter was 100 μm. With respect to the magnetic tape, the reflectance was measured at 400 points per 40 mm, and the average reflectance and the maximum variation were evaluated.
The average reflectance is a simple average value of the reflectance, and the maximum fluctuation rate is a percentage of a value obtained by dividing a maximum value of a deviation from the average reflectance by the average reflectance. The reflectivity and the maximum fluctuation rate of the flat portion after running the magnetic tape were measured by running the magnetic tape twice with an LTO drive and partially cutting the magnetic tape after running.

<Evaluation of Ra by AFM> Digital-Inst
The average surface roughness Ra was measured using a DimensionTM3100 AFM measuring device manufactured by rument. The scanning mode was a tapping mode AFM. In the tapping mode, a cantilever with a probe at the tip is vibrated near the resonance frequency (approximately 50 to 500 kHz) using a piezo vibrator, and the sample surface is intermittently lightly touched (while tapping). Scan. The change in the amplitude of the cantilever due to the unevenness of the sample surface is evaluated using laser light. The measurement visual field is 40 μm × 40 μm. In addition, Ra depending on the location
Is measured at 100 points at equal intervals per 40 mm length, Ra at each measurement point is plotted on the horizontal axis, and frequency (1 nm pitch) is plotted on the vertical axis, and the half width of Ra fluctuation is determined from this figure. .

<S / N of Servo Track> Flopti
Using a servo signal measuring section of a cal drive, light having a center wavelength of 880 nm was irradiated to the back coat layer at an incident angle of 20 degrees, and the servo signal S / N was measured from the reflected light.
The servo signals S / N of Examples 1 to 10, Reference Example 1, and Comparative Examples 2 to 7 are represented by relative values with Comparative Example 1 as a reference (0 dB). The S / N of the servo signals of Examples 11 to 19 was expressed as a relative value when the S / N of Reference Example 2 was 0 dB.

<Measurement of Error Rate> The error rate (E
RT) was measured using an LTO drive that was improved so that thin tapes could also be measured (recording wavelength 0.37 μm).
-It was done by playing. ERT is a value in the test mode.

<Evaluation of Magnetic Properties> Both the magnetic properties of the magnetic layer and the magnetic properties of the ferromagnetic powder were evaluated using a sample vibrating magnetometer manufactured by Toei Kogyo. The external magnetic field is 1.28 MA / m (16
kOe).

Tables 4 to 7 show the evaluation results of the magnetic tapes of Examples 1 to 10 and Comparative Examples 1 to 7.

[0126]

[Table 4]

[0127]

[Table 5]

[0128]

[Table 6]

[0129]

[Table 7]

As is apparent from the results of Examples 1 to 10 and Comparative Examples 1 to 7 shown in Tables 4 to 7, the average value of the light reflectance of the flat portion was 8.5% or more, The maximum variation rate of the light reflectance depending on the magnetic tape position [<the maximum value of the absolute value of (light reflectance−average value of light reflectance)> ÷ (average value of light reflectance) × 100] is 10. % Or less, the S / N of the servo signal at the initial stage is high, and the S / N of the servo signal after traveling twice is also high. Further, as is apparent from Example 1 and Reference Example 1, since the solid CO ₂ spraying process increases the error rate and the S / N of the servo signal after running twice, the processing method has a concave portion. It can be seen that this is an effective processing method for removing combustion residues in the inside.

Tables 8 and 9 show the results of evaluation of the magnetic tapes of Examples 11 to 19 and Reference Example 2.

[0132]

[Table 8]

[0133]

[Table 9]

Examples 11 to 19 shown in Tables 8 to 9
As is apparent from the results of Reference Example 2, when cleaning the surface of the back coat layer of the magnetic tape in which the concave portion for optical servo was provided in the back coat layer, the raised hair was applied to the surface of the back coat layer having the concave portion. By performing a method including a step of contacting a flocking body, a woven fabric or a non-woven fabric having the above, and removing the combustion residue attached to the concave portion and the periphery thereof, as a result, the combustion residue present in the concave portion is removed. A magnetic tape with a low error rate can be obtained.

[0135]

According to the present invention, a magnetic layer is formed on one surface of a non-magnetic support, and a back coat layer containing a non-magnetic powder and a binder is formed on the other surface, and a concave portion for optical servo is formed in the back coat layer. The average value of the light reflectance of the flat portion is 8.5% or more, and the maximum variation rate of the light reflectance of the flat portion depending on the position of the magnetic tape [<(light reflectance−light) A magnetic tape having a maximum absolute value of (average reflectance)> 率 (average light reflectance) × 100] of 10% or less has a high initial S / N of the servo signal and runs twice. The S / N of the subsequent servo signal is also high. In addition, since the error rate and the S / N of the servo signal are increased by performing a solid CO ₂ spraying process or a cleaning process by contact with a raised body, this processing method is an effective process for removing combustion residues in the concave portion. It turns out that it is a law.

[Brief description of the drawings]

FIG. 1 is a schematic diagram used for explaining a solid CO ₂ spraying treatment on a back coat layer surface of a magnetic tape in the present invention.

FIG. 2 is a schematic view used to explain an angle at which an injection nozzle for blowing CO ₂ is set in the present invention.

FIG. 3 is a perspective view showing the vicinity of a CO ₂ blowing unit and a suction unit in the optical servo track forming / cleaning apparatus used in the embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a configuration example of a suction unit (suction nozzle).

FIG. 5 is a schematic view showing another configuration example of the suction means (suction nozzle).

FIG. 6 is a perspective view showing an example of a servo pattern formed on the surface of the back coat layer of the magnetic tape.

FIG. 7 is an overall configuration diagram of an optical servo track forming / cleaning apparatus used in the embodiment of the present invention.

FIG. 8 is a perspective view showing the vicinity of a contact portion in the optical servo track forming / cleaning apparatus used in the embodiment of the present invention.

FIG. 9 is an overall configuration diagram of an optical servo track forming / cleaning apparatus used in an embodiment of the present invention.

[Explanation of symbols]

1 the magnetic tape 2 back coat layer 3 nonmagnetic support 4 magnetic layer 5 servo patterns 6 undercoat layer 11 feeding mechanism 12 optical servo track forming section 13 cleaning unit 14 take-up mechanism 15 injection nozzle 15a for a solid CO ₂ blown CO ₂ injection port 15b Contact section 16 Suction nozzle (suction means) 16a Suction port 17 Wiping section 18.19 Tissue cleaner 20.21 Roller 22.23.24 Suction roll 25.26 Tension arm 27.28 Tension detector 30 Brushed drum 31 Rotary Drum 32 Brushed Cloth (Flocked Body, Woven Fabric or Nonwoven Fabric Having Brushed Hair) 41 Guide Roller

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoki Mukai 1-1-88 Ushitora, Ibaraki-shi, Osaka Inside Hitachi Maxell Co., Ltd. (72) Satoru Fukiage 1-1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Inside Maxell Co., Ltd. (72) Kenji Sano, 1-1-88 Ushitora, Ibaraki-shi, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Shigeo Fujitani 1-1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell F term in the company (reference) 5D006 CC01 DA05 EA01 5D042 FA06 GA01 HA18 HB03 HB07 5D112 AA08 BD02 GA08 GA10 GA25

Claims (14)

[Claims] A non-magnetic support, a layer formed on one surface of the non-magnetic support, and a non-magnetic support formed on the other surface of the non-magnetic support.
A magnetic tape comprising a backcoat layer containing a nonmagnetic powder containing carbon black as a component and a binder, wherein a concave portion for optical servo is formed in the backcoat layer, wherein the backcoat layer The average value of the light reflectance of the flat portion is 8.5% or more and the maximum variation rate of the light reflectance of the flat portion depending on the position of the magnetic tape [<(the average value of (light reflectance−average value of light reflectance)) Maximum value> ÷ (average value of light reflectance) ×
[100] is 10% or less. 2. The content of nonmagnetic powder in the backcoat layer [(weight of nonmagnetic powder) ÷ (weight of nonmagnetic powder + weight of binder) × 100] is 50% by weight or more, and is measured by an atomic force microscope. The surface average roughness Ra of the flat portion of the back coat layer thus obtained is 30 nm or less, and the half width of the variation of the surface average roughness Ra depending on the position of the magnetic tape is 5 nm or less.
The magnetic tape as described. 3. A non-magnetic support, a magnetic layer formed on one surface of the non-magnetic support, and a non-magnetic powder containing carbon black as one component formed on the other surface of the non-magnetic support. A magnetic tape having a concave portion for optical servo formed by irradiating the back coat layer with a laser, wherein a solid is formed on the surface of the back coat layer. A method of cleaning a magnetic tape, comprising: removing a burning residue attached to a concave portion for optical servo and a periphery thereof caused by the laser irradiation by spraying CO ₂ . The 4. A solid CO _2, matches the arrangement pattern of recesses for optical servo in the width direction of the magnetic tape CO
4. The method for cleaning a magnetic tape according to claim 3, wherein the magnetic tape is sprayed using an injection nozzle having _two injection holes. 5. A method in which solid CO ₂ is sprayed on the surface of the back coat layer at an angle in a direction opposite to the running direction of the magnetic tape, thereby adhering to the concave portion for optical servo on the surface of the back coat layer and its periphery. The method for cleaning a magnetic tape according to claim 3 or 4, wherein the combustion waste is blown off, and the blown-off combustion waste is suctioned and removed. 6. A feeding mechanism for feeding a wound magnetic tape in a predetermined direction, and an optical servo track for forming a concave portion for optical servo by irradiating a laser beam to a surface of a back coat layer of the fed magnetic tape. A forming unit, a cleaning unit that cleans the surface of the back coat layer after the formation of the concave portion, and a winding mechanism that winds the magnetic tape after the cleaning, and the cleaning unit is formed by irradiating the laser light. Blows solid CO ₂ into and around the recess for optical servo
_{(2) a} spraying part, a suction part for sucking the combustion debris of the optical servo concave portion and its surroundings blown off by blowing the solid CO ₂ , and a wiping part for wiping the surface of the back coat layer after suction of the combustion debris. An optical servo track forming / cleaning apparatus for a magnetic tape, comprising: 7. An optical servo track forming section, and a cleaner
CO _Two Each part of spraying part and wiping part
Provided with tension control means for controlling the tension of the magnetic tape.
7. The optical servo track of a magnetic tape according to claim 6, wherein:
Forming and cleaning equipment. 8. A nonmagnetic support, a magnetic layer formed on one surface of the nonmagnetic support, and a nonmagnetic powder containing carbon black as one component formed on the other surface of the nonmagnetic support. And a back coat layer containing an agent, and a method for cleaning the surface of the back coat layer of the magnetic tape in which the concave portion for optical servo is formed by laser irradiation on the surface of the back coat layer, wherein the concave portion A step of contacting a flocked body, a woven fabric or a nonwoven fabric having raised hairs with the surface of the back coat layer having Method. 9. The raised hair has a hair diameter of 0.5 μm to 10 μm.
9. The method for cleaning a magnetic tape according to claim 8, wherein the magnetic tape comprises a single fiber having a length of 0.5 mm to 5 mm. 10. The method for cleaning a magnetic tape according to claim 8, wherein the raised hair comprises at least one of natural fibers and synthetic fibers. 11. The brushed hair comprises cotton.
11. The method for cleaning a magnetic tape according to any one of items 10 to 10. 12. Rotating or moving a flocked body, woven fabric or nonwoven fabric having raised hairs in a direction opposite to a running direction of a magnetic tape, thereby forming a concave portion for optical servo on a surface of a back coat layer and a periphery thereof. The method for cleaning a magnetic tape according to any one of claims 8 to 11, wherein the adhering combustion residue is scraped off and removed. 13. A feed mechanism for feeding a wound magnetic tape in a predetermined direction, and an optical servo track for irradiating a laser beam on a surface of a back coat layer of the fed magnetic tape to form a concave portion for optical servo. A forming unit, a cleaning unit for cleaning the surface of the back coat layer after the formation of the concave portion, and a winding mechanism for winding the magnetic tape after the cleaning, wherein the cleaning unit cleans the surface of the back coat layer. In order to contact the surface of the back coat layer, a contact portion for bringing a flocked body, woven fabric or non-woven fabric having raised hairs into contact with the surface of the back coat layer, and a wiping portion for wiping off unnecessary powder adhering to the surface of the back coat layer are arranged. An optical servo track forming / cleaning apparatus for a magnetic tape, comprising: 14. An optical servo track forming unit for a magnetic tape according to claim 13, further comprising an optical servo track forming unit and tension control means for controlling a magnetic tape tension for each of a contact unit and a wiping unit in the cleaning unit.・
Cleaning device.