Method for manufacturing polishing tape and magnetic recording medium

Abstract

We provide polishing tapes that can increase the productivity of magnetic recording media. [Solution] The polishing tape according to this disclosure is a polishing tape obtained by winding a long tape in a roll shape, on which abrasive grains are fixed as an abrasive material on one surface of a support, and the polishing tape is provided with an adhesive layer on the other surface of the support.

Description

Technical Field

[0006] , , ,

[0007] ,

[0005] , , , , ,

[0001] The present disclosure relates to a method for manufacturing a polishing tape and a magnetic recording medium.

Background Art

[0002] Magnetic storage devices have been increasingly mounted in various products such as personal computers, video recorders, and data servers in recent years, and their importance has been increasing. A magnetic storage device is a device having a magnetic recording medium that stores electronic data by magnetic recording. For example, there is a hard disk drive (HDD) device.

[0003] A general magnetic recording medium has, for example, a multilayer film in which an underlayer, an intermediate layer, a magnetic recording layer, and a protective layer are formed in this order on a non-magnetic substrate, and a lubricating layer is formed on the surface of the protective layer.

[0004] In the manufacture of a magnetic recording medium, a burnishing process using a polishing tape is performed to remove foreign substances and protrusions on the surface of the protective layer.

[0005] For example, Patent Document 1 discloses a method for smoothing the surface of a magnetic disk substrate that polishes a lubricating protective film by performing tape polishing using a wrapping film obtained by processing a lubricating protective film formed on the surface of a magnetic disk substrate into a tape shape.

[0006] Also, in order to prevent foreign substances from adhering to the polishing tape, for example, Patent Document 2 discloses a polishing tape in which a polishing layer formed on the surface of a plastic film is covered with a peelable protective film.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

[0008] In the burning process, as shown in Figure 1, an abrasive tape 100 is used, in which abrasive grains 102 such as alumina are fixed to a resin 103 on a resin film 101. The abrasive tape 100 is several centimeters wide and about 100 meters long, and is supplied wound in a roll on a core material 110.

[0009] If foreign matter or loose abrasive particles are mixed into the polishing tape 100, circumferential scratches will occur on the surface of the multilayer film during the burnishing process, making it easier for dirt to adhere. Therefore, the polishing tape 100 is manufactured under quality control to prevent the inclusion of foreign matter or loose abrasive particles during its manufacturing process. However, in the manufacturing of magnetic recording media, there was still a problem in that scratches or dirt, which are thought to be caused by the burnishing process, sometimes occurred. Magnetic recording media with scratches and dirt on the surface of the multilayer film are treated as defective products, which reduces the productivity of magnetic recording media.

[0010] One aspect of this disclosure aims to provide a polishing tape that can improve the productivity of magnetic recording media. [Means for solving the problem]

[0011] The inventors of this disclosure focused on the correlation between the occurrence rate of defective products caused by circumferential scratches and dirt on the surface of magnetic recording media and the position of the roll of polishing tape used in the burnishing process. They discovered that the occurrence rate of defective products caused by the burnishing process was higher on the outer side of the polishing tape roll compared to the inner side, which is the core material side. When the inventors of this disclosure investigated the cause, they found that the pressure caused by the winding of the polishing tape when it is rolled generated loose abrasive particles, and these loose abrasive particles were the cause of the defective products. Because the pressure caused by winding differed between the inner and outer sides of the roll, there was a difference in the amount of loose abrasive particles generated between the inner and outer sides of the roll. Therefore, the inventors of this disclosure found that by providing an adhesive layer on the back surface of the polishing tape, that is, on the side to which the abrasive particles are not bound to the support constituting the polishing tape, the winding of the polishing tape when it is rolled can be alleviated, and the adhesive layer can capture the loose abrasive particles generated by the pressure caused by winding, thereby improving the productivity of magnetic recording media.

[0012] This disclosure provides the configuration shown below. [1] An abrasive tape in which a long tape having abrasive grains fixed as an abrasive material on one surface of a support is wound into a roll, The abrasive tape comprises an adhesive layer on the other surface of the support. [2] The abrasive tape according to [1], wherein the adhesive layer comprises one or more adhesives selected from the group consisting of rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, and silicone-based adhesives. [3] The abrasive tape according to [1] or [2], wherein the support comprises one or more resins selected from the group consisting of polyester resins, polyolefin resins, acrylic resins, and polycarbonate. [4] The polishing tape according to any one of [1] to [3], further comprising a primer layer between the support and the adhesive layer. [5] The abrasive tape according to [4], wherein the undercoat layer comprises one or more adhesives selected from the group consisting of rubber resins, epoxy resins, polyurethane resins, acrylic resins, polyester resins, silicone resins, silane coupling agents, polyolefin resins, polycarbonate resins, and polyurethane resins. [6] The process includes a burning step in which the surface of a laminate in which a magnetic recording layer and a protective layer are stacked on a substrate in this order is burnished with an abrasive, A method for manufacturing a magnetic recording medium, comprising the burnishing step of using a long polishing tape, which has abrasive grains fixed as the abrasive material on one surface of a support and an adhesive layer on the other surface of the support, wound into a roll, and pressing the polishing tape supplied from the roll onto the surface of the laminate and rubbing it. [7] The step of forming a lubricating layer on the surface of the laminate is included, The method for manufacturing a magnetic recording medium according to [6], wherein the burning step involves burning the surface of the laminate on which the lubricating layer is formed with the abrasive material. [Effects of the Invention]

[0013] According to one aspect of this disclosure, the productivity of magnetic recording media can be increased. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view showing an example of abrasive tape wound into a roll. [Figure 2] This is a cross-sectional view showing an example of a magnetic recording medium being polished using a polishing tape according to an embodiment of this disclosure. [Figure 3] This is a diagram illustrating the burning process. [Figure 4] This is a magnified cross-sectional view showing an example of abrasive tape used when burning. [Figure 5] This figure shows an example of a burnishing apparatus used in the process of burnishing a laminate with polishing tape.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. For ease of understanding the description, the same reference numerals are given to the same components in each drawing, and overlapping descriptions are omitted as appropriate. Also, the scales of the respective members in the drawings may be different from the actual ones. In this specification, "~" indicating a numerical range means that the numerical values described before and after it are included as the lower limit value and the upper limit value unless otherwise specified. Also, when only the unit of the upper limit value is described in the numerical range represented by "~", it means that the lower limit value is also in the same unit.

[0016] Before explaining the polishing tape according to an embodiment of the present disclosure (hereinafter sometimes simply referred to as "this embodiment"), a magnetic recording medium polished using the polishing tape according to this embodiment will be described.

[0017] [Magnetic Recording Medium] FIG. 2 is a cross-sectional view showing an example of a magnetic recording medium polished using the polishing tape according to an embodiment of the present disclosure. As shown in FIG. 2, the magnetic recording medium 1 has a laminate 11 and lubricating layers 12 provided on both surfaces of the laminate 11.

[0018] The laminate 11 includes a magnetic recording layer 112 and a protective layer 113 laminated in this order on both surfaces of a substrate 111, starting from the substrate 111 side.

[0019] The substrate 111 is formed of a non-magnetic material. For the substrate 111, for example, a metal substrate formed of a metal material such as an aluminum alloy may be used, or a non-metal substrate formed of a non-metal material such as glass may be used. Also, a NiP alloy layer may be formed on the surfaces of these metal substrates and non-metal substrates using, for example, a plating method or a sputtering method (sometimes referred to as "sputtering").

[0020] The magnetic recording layer 112 is a layer provided for recording and reproducing information. For example, it is provided for storing data by reversing the direction of magnetization using magnetic energy supplied from the magnetic head of the HDD and maintaining that magnetization state.

[0021] The magnetic recording layer 112 can be made of an FePt-based alloy having an L10 structure, a CoPt-based alloy having an L10 structure, or a CoCrPt-based alloy having an hcp structure.

[0022] For forming the magnetic recording layer 112, general deposition methods such as sputtering or ion beam deposition can be used.

[0023] The protective layer 113 is provided to suppress corrosion of the magnetic recording layer 112, protect the magnetic recording medium 1 by suppressing damage to its surface when the magnetic head contacts it, and enhance the corrosion resistance of the magnetic recording medium 1.

[0024] The protective layer 113 can be formed from materials commonly used as protective layers for magnetic recording media, such as a hard carbon film or diamond-like carbon (DLC).

[0025] For forming the protective layer 113, general deposition methods such as sputtering or ion beam deposition can be used.

[0026] The protective layer 113 may have its surface hydrogenated or nitrogenated. By hydrogenating or nitrogenating its surface, the protective layer 113 can increase its bonding strength with the lubricating layer 12 formed on its surface.

[0027] The lubricating layer 12 is provided to suppress wear on the surface of the magnetic head and the magnetic recording medium 1 when the magnetic head comes into contact with the magnetic recording medium 1, thereby improving the corrosion resistance of the magnetic recording medium 1.

[0028] The lubricating layer 12 is formed using a lubricant. As the lubricant, a lubricant commonly used in the manufacture of magnetic recording media may be used.

[0029] The thickness of the lubricating layer 12 is preferably 5 to 10 Å. By setting the thickness of the lubricating layer 12 to 5 to 10 Å, wear on the surface of the magnetic recording medium 1 is suppressed, the corrosion resistance of the magnetic recording medium 1 is improved, and the distance between the magnetic head and the magnetic recording medium 1 in the HDD can be shortened to achieve high recording density.

[0030] [Manufacturing method for magnetic recording media] The method for manufacturing a magnetic recording medium according to this embodiment includes the steps of forming a laminate 11 by stacking a magnetic recording layer 112 and a protective layer 113 in that order on the surfaces of both main surfaces of a substrate 111 (laminated body formation step), applying a lubricant to the surface of the laminate 11 (application step), and burning the surface of the laminate 11 to which the lubricant has been applied with an abrasive (burnishing step).

[0031] In the manufacturing method of the magnetic recording medium according to this embodiment, the burnishing step may be performed before the coating step, and the surface of the laminate 11, which is not coated with lubricant, may be burnished with an abrasive.

[0032] Furthermore, in the method for manufacturing a magnetic recording medium according to this embodiment, the laminate formation step may include other steps such as forming an adhesion layer, a soft magnetic underlayer, a seed layer, or an orientation control layer between the substrate 111 and the magnetic recording layer 112.

[0033] Furthermore, in the method for manufacturing a magnetic recording medium according to this embodiment, if the laminate 11 is comprised of multiple stacked magnetic recording layers 112, the laminate formation step may include a step of forming a non-magnetic layer between the magnetic recording layers 112.

[0034] In the method for manufacturing a magnetic recording medium according to this embodiment, first, a laminate 11 is formed by stacking a magnetic recording layer 112 and a protective layer 113 in that order on the surfaces of both main surfaces of a prepared substrate 111 (laminated body formation step).

[0035] The laminate 11 can be formed using a general method for depositing the magnetic recording layer 112 and the protective layer 113.

[0036] First, a magnetic recording layer 112 is formed on the surface of both main surfaces of the substrate 111. A general film deposition method such as sputtering can be used to form the magnetic recording layer 112.

[0037] In the sputtering method, a target containing the material for forming the magnetic recording layer 112 can be used.

[0038] As a target containing the material for forming the magnetic recording layer 112, for example, an FePt-based alloy, a CoPt-based alloy, or a CoCrPt-based alloy can be used.

[0039] As for the sputtering method, DC sputtering, DC magnetron sputtering, or RF sputtering can be used.

[0040] When forming the magnetic recording layer 112, RF (Radio Frequency) bias, DC bias, or pulsed DC bias may be used as needed.

[0041] As the reactive gas, O2 gas, H2O gas, or N2 gas may be used.

[0042] The sputtering gas pressure is adjusted as needed to optimize the characteristics of each layer, but it is usually within the range of 0.1 to 30 Pa.

[0043] Next, a protective layer 113 is formed on the magnetic recording layer 112. The method for forming the protective layer 113 is not particularly limited, and general film deposition methods can be used. Examples of methods for forming the protective layer 113 include the RF-CVD (Radio Frequency-Chemical Vapor Deposition) method, in which a source gas consisting of hydrocarbons is decomposed with a high-frequency plasma to form a film; the IBD (Ion Beam Deposition) method, in which the source gas is ionized with electrons emitted from a filament to form a film; and the FCVA (Filtered Cathodic Vacuum Arc) method, in which a solid carbon target is used to form a film without using a source gas.

[0044] In this embodiment, the laminate formation process may involve forming an adhesion layer, a soft magnetic underlayer, a seed layer, or an orientation control layer between the substrate 111 and the magnetic recording layer 112.

[0045] In this embodiment, if the laminate 11 is comprised of multiple magnetic recording layers 112 stacked together, the laminate formation step may include a step of forming a non-magnetic layer between the magnetic recording layers 112.

[0046] Next, a lubricant is applied to the surface of the laminate 11 to form a lubricating layer 12 (lubricant formation step). This results in a magnetic recording medium 1, which is a multilayer body with a lubricating layer 12 formed on the surface of the laminate 11.

[0047] For applying the lubricant, common application methods such as the dip method, spin coating method, or vapor coating method can be used.

[0048] Next, as shown in Figure 3, the surfaces of the lubricating layers 12 formed on both sides of the laminate 11 are burnished with a tape containing an abrasive material (hereinafter sometimes referred to as a polishing tape) 20 (burnishing process).

[0049] The burning process involves using the abrasive tape 20 in a rolled state and pressing the abrasive tape 20 supplied from the rolled state against the surface of the laminate 11 and rubbing it.

[0050] Because the abrasive tape 20 is long, it is supplied in a rolled state, as shown in Figure 1, and is used by setting it on the reel of the burnishing device in this rolled state.

[0051] The varnishing is performed using abrasive tape 20 wound into a roll. This is done by pressing the abrasive tape 20, supplied from the roll, against the surface of the lubricating layer 12 formed on the surface of the laminate 11 and rubbing it. This makes it possible to form a varnished laminate 11 on both sides of the laminate 11.

[0052] Figure 4 is an enlarged cross-sectional view showing an example of a polishing tape 20 used when burning. As shown in Figure 4, the polishing tape 20 can polish the surface of the lubricating layer 12 formed on the surface of the laminate 11 by sliding the polishing surface S against the surface of the lubricating layer 12.

[0053] The abrasive tape 20 has an abrasive layer 22 on one surface of the support 21 and an adhesive layer 24 on the other surface of the support 21. This structure allows the adhesive layer 24 to capture loose abrasive particles that become loose when the tape is rolled up. Therefore, circumferential scratches on the surface of the lubricating layer 12 during the burnishing process, preventing dirt from adhering, can be suppressed, thereby increasing the productivity of the magnetic recording medium 1. Furthermore, because the adhesive layer 24 is easily elastically deformable, it can alleviate the tightness of the tape when it is rolled up. This suppresses the loosening of abrasive particles, further increasing the productivity of the magnetic recording medium.

[0054] The adhesive layer 24 preferably contains one or more adhesives selected from the group consisting of rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, and silicone-based adhesives. By containing such adhesives, the adhesive layer 24 can more easily capture loose abrasive grains and become more elastically deformable, thereby suppressing the loosening of abrasive grains and improving the productivity of magnetic recording media.

[0055] The thickness of the adhesive layer 24 is appropriately selected according to the particle size of the abrasive grains to be captured, but it is preferable that it be several times the particle size of the abrasive grains to be captured or more. The thickness of the adhesive layer 24 is preferably about 0.1 to 50 μm, and more preferably 0.5 to 20 μm.

[0056] The support 21 preferably contains one or more resins selected from the group consisting of polyester resins, polyolefin resins, acrylic resins, and polycarbonates. By forming the support 21 using such resins, the abrasive tape 20 can have mechanical properties, namely strength, heat resistance, and flexibility.

[0057] Suitable polyester resins include, for example, resins mainly composed of polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate. Suitable polyolefin resins include, for example, resins mainly composed of polyethylene or polypropylene. Suitable acrylic resins include, for example, resins mainly composed of polystyrene, polyvinyl chloride, polyvinyl alcohol, or methacrylic alcohol.

[0058] The thickness of the support 21 is preferably in the range of 5 to 100 μm, and more preferably in the range of 10 to 75 μm, in order to ensure the mechanical properties of the abrasive tape 20.

[0059] The abrasive layer 22 can be composed of abrasive grains 221 and a binder 222 that fixes the abrasive grains 221 to the support 21.

[0060] Examples of abrasive particles 221 include particles containing chromium oxide, α-alumina, silicon carbide, nonmagnetic iron oxide, diamond, γ-alumina, α,γ-alumina, fused alumina, corundum, or artificial diamond. The abrasive particles 221 may also be particles made from these materials. These may be used individually or in appropriate combinations of two or more types.

[0061] The binder 222 is not particularly limited, and for example, a thermosetting resin, a thermoplastic resin, or a photosensitive resin can be used. The resin used as the binder 222 may be used alone or in combination of two or more types.

[0062] Preferably, the abrasive tape 20 further includes an undercoat layer 23 between the support 21 and the adhesive layer 24. By providing the undercoat layer 23 between the support 21 and the adhesive layer 24, the adhesion between the support 21 and the adhesive layer 24 is improved, and the adhesive of the adhesive layer 24 is prevented from being transferred to the abrasive surface S and contaminating the abrasive surface S.

[0063] The undercoat layer 23 preferably contains one or more adhesives selected from the group consisting of rubber resins, epoxy resins, polyurethane resins, acrylic resins, polyester resins, silicone resins, silane coupling agents, polyolefin resins, polycarbonate resins, and polyurethane resins.

[0064] The thickness of the undercoat layer 23 is not particularly limited, but is usually in the range of 0.1 to 6 μm, and more preferably in the range of 0.5 to 3 μm.

[0065] Furthermore, when selecting the materials that constitute the support 21, the undercoat layer 23, and the adhesive layer 24, it is preferable to consider their compatibility with each other.

[0066] For example, when the adhesive layer 24 is formed using a rubber-based adhesive, the undercoat layer 23 may be formed using a rubber-based resin such as chloroprene rubber, polyisoprene, or polybutadiene, epoxy resin, or polyurethane resin. When an acrylic-based adhesive is used, the undercoat layer 23 may be formed using an acrylic resin, polyester resin, epoxy resin, or polyurethane resin. When a urethane-based adhesive is used, the undercoat layer may be formed using a polyurethane resin, epoxy resin, or acrylic resin. When a silicone-based adhesive is used, the undercoat layer 23 may be formed using a silicone resin, silane coupling agent, or epoxy resin.

[0067] When the support 21 is formed using a polyester resin, the undercoat layer 23 may be formed using a polyester resin, epoxy resin, or acrylic resin. When the support 21 is formed using a polyolefin resin, the undercoat layer 23 may be formed using a polyolefin resin, epoxy resin, or chloroprene rubber. When the support 21 is formed using an acrylic resin, the undercoat layer 23 may be formed using an acrylic resin, polyester resin, or epoxy resin. When the support 21 is formed using polycarbonate, the undercoat layer 23 may be formed using a polycarbonate resin, epoxy resin, or polyurethane resin.

[0068] As described above, since the abrasive tape 20 is long, it is supplied in a rolled state, as shown in Figure 1, and is used by setting it on the reel of the burnishing device in that rolled state.

[0069] When the abrasive tape 20 is rolled, the pressure from winding causes loose abrasive particles to form within the roll. If the pressure from winding is very high, it is possible that the abrasive particles 221 that are strongly bonded to the support 21 may become loose. However, normally, it is thought that loose particles 221 that are weakly bonded to the support 21 or particles 221 that are attached to the bonded particles 221 become loose. It is difficult to completely remove these loose abrasive particles 221 during the manufacturing process of the abrasive tape 20, and it is thought that most of them are generated after the manufacturing of the abrasive tape 20, that is, after the abrasive tape 20 has been wound into a roll.

[0070] The polishing tape 20 reduces the detachment of abrasive grains and captures any detached abrasive grains on its back surface. Therefore, even if abrasive grains detach, it is possible to suppress the adverse effects of these detached grains on the magnetic recording medium 1 during the burnishing process.

[0071] In the burning process, a method can be used in which an abrasive tape 20 is pressed against the surface of the lubricating layer 12 formed on the surface of the laminate 11 and rubbed. An example of a burning apparatus will be explained in detail with reference to the figure.

[0072] Figure 5 shows an example of a burnishing apparatus used in the process of burnishing a laminate 11 with abrasive tapes 20. As shown in Figure 5, the burnishing apparatus 50 has a pair of abrasive tapes 20 (hereinafter also referred to as "a pair of abrasive tapes 20A and 20B") arranged opposite each other so as to sandwich the laminate 11, on which a lubricating layer 12 is formed on its surface, from both sides, as well as a rotation support means 51 and a tape moving means 52.

[0073] A pair of abrasive tapes 20A and 20B are supplied in a rolled state from the first abrasive tape supply reel 53A and the second abrasive tape supply reel 53B, respectively, and are wound in a rolled state by the first abrasive tape take-up reel 54A and the second abrasive tape take-up reel 54B.

[0074] In the burnishing apparatus 50, a pair of polishing tapes 20A and 20B are positioned opposite each other so as to sandwich the laminate 11, on which a lubricating layer 12 is formed on its surface, from both sides, allowing for efficient burnishing of the laminate 11 simultaneously.

[0075] The rotational support means 51 supports the central opening of the laminate 11, which has a lubricating layer 12 formed on its surface, and rotates the laminate 11 in the circumferential direction (direction of arrow r).

[0076] The tape moving means 52 presses a pair of abrasive tapes 20A and 20B against the lubricating layers 12 formed on both surfaces of the rotated laminate 11 in the direction of arrow F, while moving the pair of abrasive tapes 20A and 20B relative to each other in the radial direction of the laminate 11.

[0077] Furthermore, the tape moving means 52 includes a pair of abrasive tape pressing means 521 and a pair of abrasive tape running systems 522, which are positioned opposite each other so as to sandwich a laminate 11, on which a lubricating layer 12 is formed on the surface, from both sides via a set of abrasive tapes 20A and 20B.

[0078] The pair of abrasive tape pressing means 521 comprises a first abrasive tape pressing means 521A and a second abrasive tape pressing means 521B. The pair of abrasive tape running systems 522 comprises a first abrasive tape running system 522A and a second abrasive tape running system 522B.

[0079] In other words, the tape moving means 52 includes a first polishing tape pressing means 521A and a first polishing tape running system 522A, which are arranged on one side of the laminate 11 on which a lubricating layer 12 is formed on the surface, and a second polishing tape pressing means 521B and a second polishing tape running system 522B, which are arranged on the other side.

[0080] The first abrasive tape pressing means 521A is a pressing member that presses the abrasive tape 20A supplied from the first abrasive tape supply reel 53A toward the laminate 11 (direction F on the left in Figure 5).

[0081] The second abrasive tape pressing means 521B is a pressing member that presses the abrasive tape 20B supplied from the second abrasive tape supply reel 53B toward the laminate 11 (direction F on the right in Figure 5).

[0082] The first abrasive tape transport system 522A has first guide rolls 523A-1 to 523A-6 and transports the abrasive tape 20A in the direction of arrow Ra.

[0083] The second abrasive tape transport system 522B has second guide rolls 523B-1 to 523B-6 and transports the abrasive tape 20B in the direction of arrow Rb.

[0084] As described above, the magnetic recording medium 1 manufactured using the manufacturing method for magnetic recording media according to this embodiment has fewer circumferential scratches and dirt on its surface, thus improving the reliability of its quality. The magnetic recording medium 1 can suppress defects in reading and recording and maintain a high recording density, making it suitable for use in magnetic recording and playback devices. The form of the magnetic recording and playback device is not particularly limited as long as it has a magnetic recording medium manufactured using the manufacturing method for magnetic recording media according to this embodiment, and may include a magnetic recording and playback device that records magnetic information on a magnetic recording medium using a heat-assisted recording method.

[0085] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present disclosure is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. The above embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Examples]

[0086] The embodiments will be described in detail below based on examples, but the embodiments are not limited to these examples.

[0087] <Manufacturing of abrasive tapes> [Example 1] A tape was prepared by bonding 0.2 μm-particle Al2O3 abrasive grains to one side of a 24 μm-thick polyethylene terephthalate tape using a thermosetting resin. This tape had a width of 12.6 mm and a length of 100 m. An acrylic resin undercoat was applied to the back of this tape to a thickness of 1 μm after drying. Then, an adhesive layer was applied on top of the undercoat to a solvent solution of an adhesive composition mainly composed of an elastomer containing 80% natural rubber and 20% liquid isoprene rubber, to a thickness of 3 μm after drying. The tape was then dried to produce an abrasive tape.

[0088] [Comparative Example 1] A polishing tape was manufactured in the same manner as in Example 1, except that a primer layer and an adhesive layer were not formed on the back surface of the tape.

[0089] <Confirmation of the degree to which desulfurized abrasive particles are captured> The polishing tapes of Example 1 and Comparative Example 1 were wound onto a core material in a roll shape under a tension of 10 N, and this roll of polishing tape was left for one week. After one week, the roll of polishing tape was unrolled, and the back surface of the polishing tape was observed using a scanning electron microscope (SEM).

[0090] In the abrasive tape of Example 1, it was confirmed that the detached abrasive grains were captured in the adhesive layer. Furthermore, it was confirmed that the amount of detached abrasive grains captured in the adhesive layer of the abrasive tape of Example 1 was less than the amount of detached abrasive grains captured in the abrasive tape of Comparative Example 1. This is thought to be because, in the abrasive tape of Example 1, the pressure due to winding was relieved, reducing the amount of abrasive grains that detached.

[0091] Therefore, the abrasive tape of Example 1 can reduce the amount of abrasive particles that fall off compared to the abrasive tape of Comparative Example 1, and can suppress the occurrence of circumferential scratches and dirt on the surface of the magnetic recording medium 1, thereby increasing the productivity of the magnetic recording medium. [Explanation of Symbols]

[0092] 1 Magnetic recording medium 11 Laminate 12 Lubricating layer 20, 20A, 20B abrasive tapes 21 Support 22 Abrasive layer 50 Burnishing Machine 53A First abrasive tape supply reel 53B Second polishing tape supply reel 54A First abrasive tape winding reel 54B Second abrasive tape winding reel 111 circuit board 112 Magnetic recording layer 113 Protective layer 221 abrasive grains 222 Binder 521 Pair of abrasive tape pressing means 522 Pair of abrasive tape transport systems 521A First polishing tape pressing means 521B Second polishing tape pressing means 522A First polishing tape transport system 522B Second polishing tape transport system S polished surface

Claims

1. An abrasive tape is formed by winding a long tape, on which abrasive grains are fixed as an abrasive material on one surface of a support, into a roll shape. The abrasive tape comprises an adhesive layer on the other surface of the support.

2. The abrasive tape according to claim 1, wherein the adhesive layer contains one or more adhesives selected from the group consisting of rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, and silicone-based adhesives.

3. The abrasive tape according to claim 1 or 2, wherein the support comprises one or more resins selected from the group consisting of polyester resins, polyolefin resins, acrylic resins, and polycarbonate.

4. The polishing tape according to claim 1 or 2, further comprising an undercoat layer between the support and the adhesive layer.

5. The abrasive tape according to claim 4, wherein the undercoat layer comprises one or more adhesives selected from the group consisting of rubber resins, epoxy resins, polyurethane resins, acrylic resins, polyester resins, silicone resins, silane coupling agents, polyolefin resins, polycarbonate resins, and polyurethane resins.

6. The process includes a burning step in which the surface of a laminate, in which a magnetic recording layer and a protective layer are laminated on a substrate in this order, is burnished with an abrasive material. A method for manufacturing a magnetic recording medium, comprising the burnishing step of using a long polishing tape, which has abrasive grains fixed as the abrasive material on one surface of a support and an adhesive layer on the other surface of the support, wound into a roll, and pressing the polishing tape supplied from the roll onto the surface of the laminate and rubbing it.

7. The process includes forming a lubricating layer on the surface of the laminate, The method for manufacturing a magnetic recording medium according to claim 6, wherein the burning step involves burning the surface of the laminate on which the lubricating layer is formed with the abrasive material.

Images