JP2006205316A - Lapping tape for polishing magnetic layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lapping tape for polishing a magnetic layer, capable of efficiently removing a sticking object and an unrequired microscopic projection in its surface, without damaging the magnetic layer of a magnetic recording medium. <P>SOLUTION: A powder particle of Mohs' hardness of 0.5 to 5 and a binding agent for dispersing these powder particles, are included in a polishing layer arranged on a nonmagnetic support. At this time, the content of the powder particle of the Mohs' hardness of 0.5 to 5 in the polishing layer is set to 25 to 85 wt.%, and the content of the binding agent is set to 15 to 75 wt.%, respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wrapping tape for polishing a magnetic layer used when manufacturing a magnetic recording medium.

  In general, a coating type magnetic recording medium is a surface treatment in which a magnetic layer in which magnetic powder is dispersed in a binder is coated on a nonmagnetic support to form a magnetic layer, and then the surface of the magnetic layer is smoothed. In such magnetic recording media, in recent years, magnetic powder having a small particle size has been used in order to increase the recording density. Although it seems that the miniaturization of the magnetic powder will continue in the future, in that case, the uniform dispersion of the magnetic powder in the binder becomes more difficult than the present, and a magnetic paint in which the magnetic powder is uniformly dispersed is obtained. It becomes increasingly difficult.

  When a magnetic layer is formed using a magnetic coating that is not completely uniform, the surface of the formed magnetic layer has insufficient powder components due to insufficient binder (for example, ferromagnetic fine powder contained in the magnetic layer). Body, non-magnetic particles such as abrasives) and, on the contrary, excess binder. These cause contamination and various adverse effects in a magnetic recording / reproducing system including a magnetic recording medium.

  For example, in a magnetic tape having many powder components that are insufficiently fixed, such powder components that are insufficiently fixed fall off when the tape is running, and as a result, the magnetic head is worn and deteriorated in a short time. Adhering to the magnetic head may cause clogging or dropout. Contamination due to excess binder on the surface of the magnetic layer can cause contamination on the surface of the magnetic head (contact surface with the magnetic tape) and the tape running system such as a guide roll in a magnetic recording / reproducing drive. This may cause various problems such as the tape running being hindered or the reproduction output being lowered. Also, if the dirt is sticky, powder components that fall off the magnetic tape during running are scraped and transferred between the magnetic tape and the drive head or guide roll, and the magnetic layer is moved by sliding. And a backcoat (BC) layer (a layer provided on the back surface of the magnetic tape, that is, the surface opposite to the magnetic layer forming surface for improving running performance and ensuring running reliability).

  In order to remove such stains on the surface of the magnetic tape that have various adverse effects, in the magnetic tape manufacturing process, the surface of the magnetic layer is wiped with a cleaning means such as a wrapping tape. In particular, surface treatment with a wrapping tape is a method that is particularly frequently used in each stage of magnetic recording medium production. Conventionally, for example, a wrapping tape that is run by a winding roll rather than a winding roll is used as a magnetic layer of the magnetic recording medium. A method of pressure contacting the surface (Patent Document 1), a method of winding a wrapping tape and a video tape (magnetic recording medium) around a cylindrical guide post, and polishing the video tape while rotating the guide post (Patent Document 2), etc. Is known.

  As this type of wrapping tape, for example, a material obtained by forming a white fused alumina abrasive (WA abrasive) over the entire surface of a substrate such as a polyester film is used. In that case, an abrasive layer (abrasive layer, that is, an abrasive layer) is formed as thick as possible on the substrate so as not to damage the surface of the magnetic layer, and the surface of the abrasive layer is calendered to obtain an extremely smooth surface. It is produced as follows.

In addition, an abrasive having a Mohs hardness equal to or greater than that of the abrasive contained in the magnetic tape is usually used for the wrapping tape for burnishing. For example, Patent Document 3 discloses a polishing tape containing diamond having an average particle diameter of 1.0 μm and a Mohs hardness of 10 as an abrasive (trade name: MA20000 [Abrasive: Diamond / Cr ₂ O ₃ / Bengara] Fuji Photo Film Co., Ltd.) The example which performed the burnish process using the product made from (refer to Example 3 etc. in the same literature) is described.

  On the other hand, as described in Patent Document 4, a surface-treated tape is also known in which a filler having a lower Mohs hardness than an abrasive contained in a magnetic layer is included as an abrasive. In Reference 4, in order to be able to remove deposits and unnecessary protrusions without damaging the surface of the magnetic layer, CaO having a Mohs hardness lower than that of the abrasive in the magnetic layer is used as the abrasive in the surface treatment tape. Inorganic materials containing

  Patent Document 5 discloses a polishing sheet containing carbon black having a Mohs hardness of 5 or less as one component of the polishing layer, which cleans a thermal head for a thermal head color recording material. Therefore, the surface of the magnetic layer, which is completely different in configuration and characteristics from the thermal head, is not intended for polishing. Moreover, the carbon black in this case is contained in the polishing layer as a conductive material for preventing electrostatic breakdown, and as the original abrasive, there are more powders having a Mohs hardness of more than 5 than carbon black. include.

JP-A-4-205817 JP-A-2-161615 JP-A-6-52544 JP 2002-342917 A Japanese Patent Laid-Open No. 9-1555749

  When a wrapping tape containing alumina or titanium oxide as a main component of the polishing layer is used, fine protrusions on the surface of the magnetic layer can be removed, but the surface of the magnetic layer may be damaged if the magnetic layer is brittle. For this reason, when the magnetic recording medium is used, the magnetic layer coating is further broken due to contact between the magnetic layer and the magnetic head, and in the worst case, clogging of the head (head clog) is caused. Moreover, in the wrapping tape containing the hard powder as described above, since the portion other than the protrusion is a smooth surface, the wiping efficiency may be lowered.

  Particularly in recent coating-type high recording density magnetic recording media, not only ultrafine magnetic powder is used, but also a resin having a relatively low molecular weight is often used as a binder. The layers are becoming fragile and are more susceptible to damage by abrasive tape. For this reason, there is an increasing need for a wrapping tape that can remove surface protrusions and deposits without damaging such a delicate magnetic layer.

  In addition, the same problem occurs in varnish processing that scrapes the surface using sapphire, diamond, tungsten carbide, etc., so a surface treatment method that removes deposits and unnecessary protrusions without damaging the magnetic layer surface more. Development was required.

  When such a hard powder is blended, the polishing layer becomes hard and does not become dented, or only the hard powder contacts the surface to be polished, that is, the magnetic layer surface, thereby reducing the contact area. When polishing with such a wrapping tape, even if the original purpose of removing protrusions on the surface of the magnetic layer can be achieved, there is a disadvantage that the surface of the magnetic layer is damaged at the same time.

  In order to solve such a problem, in Patent Document 4 described above, an example in which CaO (Mohs hardness 1), which is a filler having a Mohs hardness of 5 or less, is used as a component of the polishing layer. The powder is limited to CaO and further contains titanium oxide having a Mohs hardness of 6 as the main powder, which is insufficient in terms of preventing damage to the medium.

  The present invention addresses the above-described problems, and provides a magnetic layer polishing wrapping tape that can efficiently remove deposits and unnecessary fine protrusions on the surface of the magnetic recording medium without damaging the magnetic layer. The purpose is to do.

  In order to remove the unnecessary fine protrusions on the magnetic layer surface of the magnetic recording medium and to perform the original polishing so as not to damage the magnetic layer surface, a magnetic recording medium is used by using a polishing layer containing a relatively soft powder. It is necessary to increase the contact area between the wrapping tape and the lapping tape so that the entire polishing surface of the wrapping tape is in contact with the magnetic layer surface of the magnetic recording medium. Also, when polishing with a wrapping tape with a relatively soft polishing surface, the wrapping tape is scraped off, so that unnecessary deposits and microprojections on the surface of the magnetic layer can be removed, so the polishing surface of the wrapping tape Is preferably a relatively soft structure. From this point of view, the magnetic layer polishing wrapping tape of the present invention is configured as follows as means for solving the above-mentioned problems.

  That is, the lapping tape for polishing a magnetic layer of the present invention has a nonmagnetic support and a polishing layer provided on the nonmagnetic support, and the polishing layer has a Mohs hardness of 0.5 to 5 Powder particles and a binder for dispersing these powder particles, and the content of the powder particles having a Mohs hardness of 0.5 to 5 in the polishing layer is 25 to 85% by weight. The content is 15 to 75% by weight.

  Here, in addition to the powder particles, the polishing layer preferably contains 0.5 to 15% by weight of powder particles having a Mohs hardness of more than 5 and 9 or less. Moreover, it is preferable that the powder particles having a Mohs hardness of 0.5 to 5 in the polishing layer are composed of conductive particles. These points will be described later.

  According to the present invention, since an appropriate amount of powder having an appropriate hardness is included in the polishing layer, deposits and unnecessary protrusions on the surface of the magnetic layer can be removed without damaging the surface of the magnetic layer.

  Hereinafter, preferred embodiments that can be adopted in carrying out the present invention, including the best mode for carrying out the present invention, will be described. In the following, a wrapping tape for polishing a polishing layer of a magnetic tape will be described. Of course, the wrapping tape of the present invention can also be used for surface treatment of a disk-shaped coated magnetic recording medium such as a flexible disk. It is.

The magnetic layer polishing wrapping tape of the present invention has a nonmagnetic support and a polishing layer provided on the nonmagnetic support, and further improves the running reliability of the wrapping tape. Therefore, it is preferable that the back coat layer is provided on the back surface of the nonmagnetic support, that is, the surface opposite to the surface on which the polishing layer is formed.
Is preferred.

  The polishing layer of the wrapping tape of the present invention contains predetermined powder particles serving as a filler and a binder for dispersing the powder particles. Among these, the binder is divided into a resin component and a curing agent component blended as necessary. As the powder particles, those having a Mohs hardness of 0.5 to 5 are used. When the Mohs hardness is less than 0.5, the lapping tape polishing layer itself is easily scraped off during lapping, and the effect of removing dirt on the surface of the magnetic tape cannot be obtained. Also, if the Mohs hardness exceeds 5, the polishing layer of the wrapping tape becomes difficult to scrape, and not only the entire wrapping tape but also a part of it contacts the magnetic tape. It becomes easy to hurt. A more preferable range of the Mohs hardness of the powder particles is 1 to 4.5. Examples of powder particles having a Mohs hardness of 0.5 to 5 include carbon black, talc, ZnO, aluminum, and mica.

Among these powder particles, those having conductivity are more preferable. The surface specific resistance, which is an index of conductivity in the polishing layer of the wrapping tape, is preferably 10 ³ to 10 ⁹ Ω / sq, more preferably 10 ⁴ to 10 ⁷ Ω / sq. This is because, if there is conductivity, the effect of suppressing charging prevents foreign matters such as dust, which may damage the magnetic tape or cause dropout, during surface treatment. Examples of conductive powder particles include carbon black and graphite.

  The amount of powder particles having a Mohs hardness of 0.5 to 5 contained in the polishing layer is set to 25 to 85% by weight with respect to the total weight of the polishing layer. When the content of the powder particles is less than 25% by weight, the effect of removing the dirt on the magnetic tape surface is reduced. When the content exceeds 85% by weight, the elastic modulus of the polishing layer formed as a coating film is increased and polishing is performed. The amount of deformation of the layer is reduced. For this reason, uniform (overall) contact with the magnetic tape cannot be achieved, the dirt removal effect of the whole magnetic tape is lowered, the adhesive force of the polishing layer is lowered, and dirt on the magnetic tape cannot be collected. The amount of powder can be determined by weighing at the time of blending, and can be identified by thermal analysis of the polishing layer.

  Further, it is not excluded that the polishing layer in the present invention contains powder particles having a Mohs hardness of 5 or more in a range of less than 15% by weight per coating weight.

  The amount of the binder (including the resin component and the crosslinking agent) contained in the polishing layer is 15% to 75% per coating weight, but preferably 40% to 60%. If the binder content is higher than 75%, the wrapping tape is likely to be charged, which may cause dust to get involved in the burnish process, causing foreign matter to adhere to the magnetic tape, or scratching. Increases nature. On the other hand, when the content ratio of the binder is lower than 15%, the elastic modulus of the coating film increases and the deformation amount of the coating film decreases. As a result, the contact with the entire magnetic tape is deteriorated and the effect of removing dirt is reduced, or the polishing layer of the wrapping tape is scraped off during burnishing to increase the solid content. The dirt will not be collected. As a crosslinking agent contained in the polishing layer, a polyisocyanate compound is usually suitable.

  The thickness of the polishing layer is preferably 2 to 8 μm, more preferably 3 to 7.5 μm. When the thickness of the polishing layer is less than 2 μm, the amount of scraping of the entire coating film is reduced, so that the adhesion to the magnetic tape is deteriorated during the burnishing process, and the dirt removing effect is lowered. On the other hand, if it is thicker than 8 μm, it will be pulled greatly in the direction of the coating film, so it is not suitable as a wrapping tape.

  The center line average roughness Ra of the polishing layer surface of the present invention is preferably in the range of 10 to 100 nm, and the ten-point average roughness Rz is preferably in the range of 80 to 800 nm. Further, Ra is more preferably in the range of 30 to 80 nm, and Rz is more preferably in the range of 240 to 640 nm. If Ra is less than 10 nm and Rz is less than 80 nm, the polishing ability with respect to the magnetic recording medium may be significantly reduced. On the other hand, if Ra exceeds 100 nm and Rz exceeds 800 nm, the polishing ability is too large, and the magnetic recording medium may be damaged, eventually causing a dropout or the like.

  The thickness of the nonmagnetic support used in the present invention is preferably in the range of 2.5 to 50 μm, more preferably in the range of 14 to 33 μm. As the material for the nonmagnetic support, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, and polyamides such as aramid are preferable.

  As described above, it is preferable to provide a backcoat layer on the back surface side of the nonmagnetic support for improving running performance. The thickness of the back coat layer is preferably 0.2 to 0.8 μm. If the thickness of the back coat layer is less than 0.2 μm, the running performance may not be sufficiently improved. If the thickness exceeds 0.8 μm, the total thickness of the wrapping tape becomes thick, and the amount of tape per roll (1 roll) The total length of the tape is small. The back coat layer can be formed by applying a paint in which a filler is dispersed in a binder. In this case, the application is performed using a conventionally known apparatus such as gravure coating, roll coating, blade coating, or die coating. It can be carried out.

  Examples of the present invention will be described below. In addition, "part" about the component in a following example and a comparative example shows a weight part.

《Paint component for polishing layer of wrapping tape》
(1)
Iron oxide (average particle size: 0.4 μm, Mohs hardness 6) 10 parts Carbon black (average particle size: 25 nm, Mohs hardness 1) 78 parts Carbon black (average particle size: 370 nm, Mohs hardness 1) 10 parts polyurethane resin (manufactured by Toyobo Co., Ltd. UR8300) (- S0 ₃ Na group-containing) 27 parts cyclohexanone 47 parts toluene 47 parts (2)
Alumina (average particle size: 170 nm, Mohs hardness 9) 2 parts Cyclohexanone 117 parts Toluene 117 parts (3)
・ Nitrocellulose 170 parts ・ Isocyanic crosslinking agent 35 parts ・ Cyclohexanone 1036.5 parts ・ Toluene 1036.5 parts ・ Ethyl acetate 11 parts

  After kneading (1) in the coating component for the polishing layer of the wrapping tape with a kneader, (2) is added and stirred, and then a sand mill dispersion treatment is performed with a residence time of 5 minutes. The filtered one was used as a polishing layer coating for a wrapping tape. This coating material for polishing layer was applied on a nonmagnetic support made of a polyethylene terephthalate film having a thickness of 21 μm so that the thickness after drying was 2.0 μm, and dried to obtain a raw sheet for a wrapping tape. The raw sheet thus obtained was aged at 70 ° C. for 72 hours in a state of being wound around a core, and then slitted to a width of 1/2 inch (about 1.27 mm), whereby the wrapping tape of Example 1 was obtained. Produced.

  Except that the blending amount of nitrocellulose in the paint component (3) for Example 1 in Example 1 was changed to 70 parts, the blending amount of isocyanate-based crosslinking agent was 25 parts, and the blending amount of ethyl acetate was changed to 8 parts. A wrapping tape was produced in the same manner as in Example 1.

  In the coating component (1) for the polishing layer of Example 1, the blending amount of iron oxide is 0 part, the blending amount of carbon having an average particle size of 370 nm is 20 parts, the blending amount of polyurethane resin is 0 part, (2) The blending amount of alumina in 0 is changed to 0 parts, the blending amount of nitrocellulose in (3) is changed to 16 parts, the blending amount of isocyanate-based crosslinking agent is changed to 8 parts, and the blending amount of ethyl acetate is changed to 2.5 parts. A wrapping tape was produced in the same manner as in Example 1 except for.

  A wrapping tape was produced in the same manner as in Example 1 except that the total amount of carbon black having an average particle size of 25 nm and 370 nm in the paint component (1) for the polishing layer of Example 1 was changed to ZnO powder having a Mohs hardness of 4. .

  A wrapping tape was produced in the same manner as in Example 1 except that the polishing layer was coated so that the thickness after drying of the coating film was 0.5 μm.

  A wrapping tape was produced in the same manner as in Example 1 except that the thickness of the polishing layer after drying was 3 μm.

  A wrapping tape was produced in the same manner as in Example 1 except that the thickness of the polishing layer after drying was 7 μm.

  A wrapping tape was produced in the same manner as in Example 1 except that the thickness of the polishing layer after drying was 8 μm.

  A wrapping tape was produced in the same manner as in Example 1 except that all of the toluene in the paint component (1), (2), and (3) for the abrasive layer in Example 1 was changed to methyl ethyl ketone.

  A wrapping tape was produced in the same manner as in Example 1 except that the dried raw sheet was calendered at 80 ° C. and 15 kgf / cm (15 × 9.8 N / cm).

[Comparative Example 1]
All the carbon blacks having an average particle diameter of 25 nm and 370 nm and alumina having an average particle diameter of 170 nm in the paint component (1) for the polishing layer of Example 1 were changed to TiO ₂ having an average particle diameter of 50 nm and a Mohs hardness of 5.5. A wrapping tape was produced in the same manner as Example 1 except for the above.

[Comparative Example 2]
A wrapping tape was produced in the same manner as in Example 1 except that carbon black of 25 nm and 370 nm in the coating component (1) for the abrasive layer of Example 1 was changed to alumina having a particle size of 170 nm and a Mohs hardness of 9.

[Comparative Example 3]
A wrapping tape was produced in the same manner as in Example 1 except that the carbon black having an average particle size of 370 nm in the coating component (1) for the polishing layer in Example 1 was changed to alumina having an average particle size of 170 nm and a Mohs hardness of 9. did.

[Comparative Example 4]
In the coating component (1) for the polishing layer of Example 1, the blending amount of iron oxide is 0 part, the blending amount of carbon having an average particle diameter of 370 nm is 22 parts, the blending amount of polyurethane resin is 0 part, (2) The amount of alumina was changed to 0 parts, the amount of nitrocellulose in (3) was changed to 9 parts, the amount of isocyanate crosslinking agent was changed to 8 parts, and the amount of ethyl acetate was changed to 2.5 parts. A wrapping tape was produced in the same manner as in Example 1 except that.

[Comparative Example 5]
The iron oxide in the coating component (1) for the polishing layer in Example 1 was changed to 13 parts of NiO having an average particle size of 300 nm, and carbon having an average particle size of 370 nm and an average particle size of 25 nm was changed to CaO having an average particle size of 300 nm. The amount of polyurethane resin was changed to 74 parts, the amount of polyurethane resin was changed to 15 parts, the alumina in (2) was changed to TiO ₂ with an average particle size of 0.3 μm, and the amount of 13 parts was changed to nitro in (3). A wrapping tape was prepared in the same manner as in Example 1, except that the cellulose content was changed to 0 parts, the isocyanate crosslinking agent content was changed to 0 parts, and the ethyl acetate content was changed to 0 parts. .

[Comparative Example 6]
The blending amount of iron oxide in the coating component (1) for the polishing layer of Example 1 is 0 part, and the blending amount of carbon black having an average particle diameter of 17 nm is 50 parts instead of two types of carbon blacks having different particle diameters. The blending amount of the polyurethane resin is 12 parts, the average particle size of alumina in (2) is 3 μm, the blending amount is 50 parts, the blending amount of nitrocellulose in (3) is 0 part, and the blending amount of isocyanate crosslinking agent A wrapping tape was prepared in the same manner as in Example 1 except that the amount of ethyl acetate was changed to 3 parts and the amount of ethyl acetate was changed to 1 part.

[Comparative Example 7]
In the polishing layer paint component (1) of Example 1, the blending amount of iron oxide is 0 part, the blending amount of carbon having an average particle size of 370 nm is 0 part, the blending amount of polyurethane resin is 50 parts, (2) A wrapping tape was produced in the same manner as in Example 1 except that the amount of alumina was changed to 0 parts.

[Comparative Example 8]
In the coating component (1) for the polishing layer of Example 1, the blending amount of iron oxide is 0 part, the blending amount of carbon having an average particle diameter of 370 nm is 22 parts, the blending amount of polyurethane resin is 0 part, (2) The amount of alumina in 2 is changed to 2 parts, the amount of nitrocellulose in (3) is changed to 9 parts, the amount of isocyanate crosslinking agent is changed to 8 parts, and the amount of ethyl acetate is changed to 2.5 parts. A wrapping tape was produced in the same manner as in Example 1 except that.

[Evaluation]
The lapping tape obtained in each of the above Examples and Comparative Examples was used to polish the surface of the magnetic layer of the magnetic tape, and the soil removal evaluation was performed. The evaluation method is as follows.

  While running a 1/2 inch (about 1.27 mm) wide magnetic tape (ultra high capacity LTO2 tape) at a speed of 200 m / min, the surface of the magnetic tape was wrapped with the above wrapping tape and super steel blade, Toraysee made by Toray Industries, Inc. The surface was wiped off using (trade name).

  The magnetic tape after the surface wiping treatment was wound on a reel, and the actual machine was run for 24 hours at a running speed of 2 m / sec in a reel-reel tester equipped with a mock head for dirt evaluation. Thereafter, the simulated head was observed with an optical microscope, and the degree of contamination was evaluated (4-step evaluation: good 0 ← → bad 3, that is, 0 was the best and 3 was the worst). If it is determined to be 2 or less in this evaluation, it has been confirmed that no problem occurs in practice. In this dirt evaluation, “0” indicates that no dirt is observed on both the head and the outrigger, “1” indicates that some dirt is seen on the outrigger, and “2” indicates that dirt is seen near the head. Means that there is no dirt, and “3” means that dirt is seen on the head.

  For measuring the surface properties of the wrapping tape, an optical interference type surface roughness measuring device Maximum-2000 manufactured by ZYGO was used, and the MIRAU lens, center line average roughness Ra and 10-point average roughness Rz in a 175 × 175 μm visual field were measured. evaluated.

  The evaluation of the contact property of the wrapping tape with respect to the magnetic tape was evaluated by the effective area ratio of the wrapping tape after use as shown below. From the viewpoint that contact with the magnetic tape is important for removing dirt from the wrapping tape, the microscopic photograph of the surface of the wrapping tape after the processing experiment is binarized with a threshold value based on the wrapping tape before the processing experiment, and the surface treatment The area of the area where the reflectivity of the wrapping tape surface was changed was obtained, and the ratio with the total area was expressed. A larger value means that the tape is rubbed as a whole.

  The damage evaluation of the magnetic tape was performed as follows. The magnetic tape for which the smear test was completed was observed using an optical microscope at five locations every 1 m. In a 3 mm × 5 mm field of view, a flaw having a width of 50 μm and a length of 1 mm or more was found to be flawed if it was found in any one of the five places, and no flaw was found if all five places were not found.

The surface resistivity of the polishing layer in the wrapping tape was measured as follows. A piece of tape with a width of 12.65 mm and a length of 150 mm is cut out along the longitudinal direction from the produced original sheet for wrapping tape (the original sheet just before making the wrapping tape by slitting), and two electrodes are used. The bars (quadrature with a cross section of 10 mm radius) were placed apart by a distance equal to the width of the sample, and the sample was placed so that its length direction was perpendicular to the electrode and the measurement surface was in contact with the electrode. Next, a load was applied to both ends of the sample so that the tension was 5 N / mm ² , the electrical resistance between both electrodes was measured, and the obtained value was defined as the surface specific resistance.

  Tables 1 and 2 show the evaluation results of the wrapping tapes obtained in the examples and comparative examples, respectively.

  From the results of Tables 1 and 2, it can be seen that the wrapping tapes obtained in the respective examples of the present invention have higher polishing performance than the wrapping tapes obtained in the respective comparative examples. Similarly, it can be seen that the wrapping tapes obtained in the examples of the present invention do not damage the magnetic layer.

Claims (3)

A magnetic layer polishing wrapping tape for polishing a magnetic layer of a magnetic recording medium,
A nonmagnetic support and a polishing layer provided on the nonmagnetic support;
The polishing layer comprises powder particles having a Mohs hardness of 0.5 to 5, and a binder for dispersing the powder particles.
Magnetic layer polishing characterized in that the content of powder particles having a Mohs hardness of 0.5 to 5 in the polishing layer is set to 25 to 85% by weight and the content of a binder is set to 15 to 75% by weight, respectively. Wrapping tape for   The lapping layer for polishing a magnetic layer according to claim 1, wherein the polishing layer contains 0.5 to 15% by weight of powder particles having a Mohs hardness of more than 5 and not more than 9 in addition to the powder particles. tape.   The wrapping tape for polishing a magnetic layer according to claim 1 or 2, wherein the powder particles having a Mohs hardness of 0.5 to 5 in the polishing layer are composed of conductive particles.