Method for manufacturing magnetic recording medium

Abstract

The invention provides a method for manufacturing a magnetic recording medium capable of improving the productivity of the magnetic recording medium. This method for manufacturing a magnetic recording medium comprises: a finishing step for finishing the surface of a laminated body in which a magnetic recording layer and a protective layer are laminated in this order on a substrate by means of an abrasive material, said finishing step comprising: using a long abrasive tape in a state in which the abrasive tape is wound into a roll; and a scraping step for scraping the surface of the laminated body by pressing the abrasive tape, which is supplied from the state of being wound into the roll shape and in which abrasive grains are adhered to a support as the abrasive material, on the surface of the laminated body, using the abrasive tape from which free abrasive grains have been removed by being rewound in advance, and scraping the surface of the laminated body by pressing the abrasive tape on the surface of the laminated body. And the grinding belt is wound into the roll shape.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a magnetic recording medium. Background Technology

[0002] In recent years, magnetic storage devices have been installed in various products such as personal computers, motion picture recorders, and data servers, and their importance is increasing. Magnetic storage devices are devices that use magnetic recording media to store electronic data through magnetic recording, such as hard disk drives (HDDs).

[0003] Typical magnetic recording media include multilayer films, which are made by sequentially forming a base layer, an intermediate layer, a magnetic recording layer and a protective layer on a non-magnetic substrate, and forming a lubricating layer on the surface of the protective layer.

[0004] When manufacturing magnetic recording media, a finishing process using an abrasive belt is performed to remove foreign matter and protrusions from the surface of the protective layer (see, for example, Patent Document 1).

[0005] Patent Document 1: Japanese Patent Publication No. 2-10486 Summary of the Invention

[0006] <Problem to be solved by this invention>

[0007] In the burning process, such as Figure 1 As shown, an abrasive belt 100 is used, which is formed by attaching abrasive particles 102 such as alumina to a resin film 101 with resin. The abrasive belt 100 is a long strip several centimeters wide and about 100m long, and is supplied in a state of being wound on a core material 110.

[0008] If foreign matter or free abrasive particles are mixed into the polishing belt 100, circumferential scratches will occur on the surface of the multilayer film during the finishing process, and dirt will easily adhere. Therefore, the polishing belt 100 is manufactured with quality control measures in place to prevent the introduction of foreign matter or free abrasive particles during the manufacturing process. However, in the manufacturing of magnetic recording media, problems such as scratches or dirt that may be attributed to the finishing process still exist. Magnetic recording media with scratches and dirt on the surface of the multilayer film are treated as defective products, reducing the productivity of magnetic recording media.

[0009] One aspect of the present invention is to provide a method for manufacturing a magnetic recording medium that can improve the productivity of magnetic recording media.

[0010] <Methods for solving problems>

[0011] The inventors of this invention focused on the correlation between the rate of defective products caused by circumferential scratches and dirt on the surface of magnetic recording media and the position of the polishing tape spool used in the finishing process. They discovered that the rate of defective products caused by the finishing process increases on the outer side of the polishing tape spool compared to the inner side (core side). Investigation revealed that the pressure generated by winding and tightening the polishing tape into a spool creates free abrasive particles, which contribute to the defective products. Because the pressure generated by winding and tightening differs between the inner and outer sides of the spool, the amount of free abrasive particles generated differs between the inner and outer sides. Therefore, the inventors of this invention discovered that by rewinding the polishing tape, which is wound into a spool, before use and removing free abrasive particles, the productivity of magnetic recording media can be improved.

[0012] The present invention includes the following constituent elements.

[0013] [1] A method for manufacturing a magnetic recording medium, comprising:

[0014] The finishing process involves using an abrasive material to finish the surface of the laminate, in which a magnetic recording layer and a protective layer are sequentially stacked on a substrate.

[0015] The finishing process includes:

[0016] The long abrasive strip is used while wound into a cylindrical shape, and the abrasive strip supplied from the wound cylindrical shape is pressed against the surface of the laminate to scrape. The abrasive strip has abrasive grains attached to the support as the abrasive material.

[0017] The grinding belt, which has had free abrasive grains removed by rewinding, is used as the grinding belt wound into the cylindrical shape.

[0018] [2] The method for manufacturing a magnetic recording medium according to [1], wherein the free abrasive grains are abrasive grains that are freed from the support of the abrasive belt.

[0019] [3] The method for manufacturing a magnetic recording medium according to [1] or [2], wherein the free abrasive particles are removed by purging with gas.

[0020] [4] The method of manufacturing a magnetic recording medium according to [1] or [2], wherein the free abrasive particles are removed by bringing another strip into contact with the surface of the abrasive strip and causing the free abrasive particles to be adsorbed onto the other strip.

[0021] [5] A method for manufacturing a magnetic recording medium according to any one of [1] to [4], comprising:

[0022] The lubricating layer formation process involves forming a lubricating layer on the surface of the laminate.

[0023] In the finishing process, the surface of the laminate on which the lubricating layer is formed is finished using the abrasive material.

[0024] <The Effects of the Invention>

[0025] According to one aspect of the present invention, the productivity of magnetic recording media can be improved. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing an example of an abrasive belt wound into a cylindrical shape.

[0027] Figure 2 This is a cross-sectional view showing an example of a magnetic recording medium manufactured by a method for manufacturing a magnetic recording medium according to an embodiment of the present invention.

[0028] Figure 3 This diagram is used to illustrate the finishing process.

[0029] Figure 4 This is an enlarged cross-sectional view showing an example of an abrasive belt containing abrasive material used during finishing.

[0030] Figure 5 This is a schematic diagram illustrating an example of a method for removing free abrasive particles.

[0031] Figure 6 This is a schematic diagram illustrating an example of a method for removing free abrasive particles.

[0032] Figure 7 This figure shows an example of a finishing apparatus used in a process of finishing the surface of a laminate using an abrasive belt.

[0033] Explanation of reference numerals in the attached figures

[0034] 1. Magnetic recording media

[0035] 11-layered structure

[0036] 11A Multilayer

[0037] 12 Lubricating layer

[0038] 20, 20A, 20B grinding belts

[0039] 21 Support body

[0040] 22 Abrasive Material Layer

[0041] 31 Supply-side reel

[0042] 32 guide rollers

[0043] 33 Winding Reel

[0044] 34 Gas Nozzle

[0045] 41 Grinding belt supply side reel

[0046] 42 guide rollers

[0047] 43 Grinding belt winding reel

[0048] 44 Another belt

[0049] 45 Another supply-side reel

[0050] 46 Another winding spool

[0051] 50 Finishing Equipment

[0052] 53A First Grinding Belt Supply Side Roller

[0053] 53B Second Grinding Belt Supply Side Reel

[0054] 54A First Grinding Belt Winding Reel

[0055] 54B Second Grinding Belt Winding Reel

[0056] 111 substrate

[0057] 112 Magnetic Recording Layer

[0058] 113 Protective Layer

[0059] 221 abrasive grains

[0060] 222 Adhesive

[0061] 521 A pair of grinding belt pressing parts

[0062] 522 A pair of grinding belt walking systems

[0063] 521A First Grinding Belt Pressing Component

[0064] 521B Second Grinding Belt Pressing Component

[0065] 522A First Grinding Belt Traveling System

[0066] 522B Second Grinding Belt Traveling System

[0067] S grinding surface. Detailed Implementation

[0068] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, for ease of understanding, the same reference numerals are used to denote the same constituent elements in each drawing, and repetitive descriptions are omitted where appropriate. Additionally, the scales of the components in the drawings may sometimes differ from actual measurements. In this specification, the tilde “~” indicating a numerical range means that, unless otherwise specified, the values ​​described before and after it are considered the lower and upper limits. Furthermore, when only the unit of the upper limit is described in the numerical range indicated by “~”, the lower limit is also described in the same unit.

[0069] Before describing the manufacturing method of the magnetic recording medium according to an embodiment of the present invention, the magnetic recording medium manufactured by the manufacturing method of the magnetic recording medium according to this embodiment will be described first.

[0070] [Magnetic recording media]

[0071] Figure 2 This is a cross-sectional view showing an example of a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium according to this embodiment. Figure 2 As shown, the magnetic recording medium 1 includes a laminate 11 and a lubricating layer 12 disposed on two surfaces of the laminate 11.

[0072] The laminate 11 has a magnetic recording layer 112 and a protective layer 113 on two sides of the substrate 111, and the magnetic recording layer 112 and the protective layer 113 are stacked sequentially from the substrate 111 side.

[0073] The substrate 111 is formed of a non-magnetic material. The substrate 111 can be a metal substrate, for example, formed of a metallic material such as aluminum alloy, or a non-metallic substrate, for example, formed of a non-metallic material such as glass. Furthermore, a NiP alloy layer can be formed on the surface of these metal or non-metallic substrates, for example, using electroplating or sputtering.

[0074] The magnetic recording layer 112 is a layer configured to record and reproduce information, for example, to store data by using magnetic energy provided from the HDD's magnetic head to reverse the magnetization direction and maintain the magnetization state.

[0075] The magnetic recording layer 112 can be made of FePt alloys with an L10 structure, CoPt alloys with an L10 structure, CoCrPt alloys with an hcp structure, etc.

[0076] The magnetic recording layer 112 can be formed using known methods such as sputtering and ion beam deposition.

[0077] The protective layer 113 is configured to suppress corrosion of the magnetic recording layer 112 and to protect the surface of the magnetic recording medium 1 from damage when the magnetic head contacts the magnetic recording medium 1, while also improving the corrosion resistance of the magnetic recording medium 1.

[0078] The protective layer 113 can be formed from known materials, such as hard carbon film and diamond-like carbon (DLC).

[0079] The protective layer 113 can be formed using known methods such as sputtering and ion beam deposition.

[0080] The surface of the protective layer 113 can also be hydrogenated or nitrided. By hydrogenating or nitriding the surface of the protective layer 113, the adhesion to the lubricating layer 12 formed on its surface can be enhanced.

[0081] The lubricating layer 12 is configured to suppress wear on the surfaces of the magnetic head and the magnetic recording medium 1 when the magnetic head comes into contact with the magnetic recording medium 1, and to improve the corrosion resistance of the magnetic recording medium 1.

[0082] The lubricating layer 12 is formed of a lubricant. As a lubricant, a lubricant commonly used in the manufacture of magnetic recording media can be used.

[0083] The thickness of the lubricating layer 12 is preferably... By setting the thickness of the lubrication layer 12 to It can suppress wear on the surface of the magnetic recording medium 1 and improve the corrosion resistance of the magnetic recording medium 1. At the same time, it can achieve high recording density by shortening the distance between the magnetic head and the magnetic recording medium 1 in the HDD.

[0084] [Manufacturing methods for magnetic recording media]

[0085] The method for manufacturing a magnetic recording medium according to this embodiment includes: a step of forming a laminate 11 (laminate forming step), wherein the laminate 11 is formed by sequentially laminating a magnetic recording layer 112 and a protective layer 113 on the surfaces of two main surfaces of a substrate 111; and a step of polishing the surface of the laminate 11 coated with a lubricant using an abrasive material (polishing step).

[0086] It should be noted that in the manufacturing method of the magnetic recording medium according to this embodiment, the finishing process can also be performed before the coating process, and the surface of the laminate 11 without lubricant coating is finished using an abrasive material.

[0087] Furthermore, in the method for manufacturing a magnetic recording medium according to this embodiment, the laminate formation process may also include other processes, such as forming an adhesion layer, a soft magnetic substrate layer, a seed layer, and an orientation control layer between the substrate 111 and the magnetic recording layer 112.

[0088] Furthermore, in the method for manufacturing a magnetic recording medium according to this embodiment, when the laminate 11 has a plurality of stacked magnetic recording layers 112, the laminate forming process may include a process of forming non-magnetic recording layers between the magnetic recording layers 112.

[0089] In the method for manufacturing a magnetic recording medium according to this embodiment, firstly, a laminate 11 is formed (laminate forming process), which is formed by sequentially stacking a magnetic recording layer 112 and a protective layer 113 on the surfaces of two main surfaces of a prepared substrate 111.

[0090] The laminate 11 can be formed using conventional film-forming methods for the magnetic recording layer 112 and the protective layer 113.

[0091] First, a magnetic recording layer 112 is formed on the surfaces of the two main surfaces of the substrate 111. As a method for forming the magnetic recording layer 112, conventional film formation methods such as sputtering (also known as "sputtering film formation") can be used.

[0092] In sputtering, a target containing a material that forms the magnetic recording layer 112 can be used.

[0093] As a target material containing the material forming the magnetic recording layer 112, for example, FePt alloys with an L10 structure, CoPt alloys with an L10 structure, and CoCrPt alloys can be used.

[0094] As a sputtering method, DC sputtering, DC magnetron sputtering, and RF sputtering can be used.

[0095] When forming the magnetic recording layer 112, RF (radio frequency) bias, DC (direct current) bias, and pulsed DC bias can be used as needed.

[0096] As reactive gases, O2, H2O, and N2 can be used.

[0097] The pressure of the sputtering gas is adjusted appropriately to optimize the properties of each layer, generally within the range of about 0.1 to 30 Pa.

[0098] Next, a protective layer 113 is formed on the magnetic recording layer 112. There are no particular limitations on the method for forming the protective layer 113. For example, conventional film formation methods can be used, such as RF-CVD (Radio Frequency-Chemical Vapor Deposition), which uses high-frequency plasma to decompose a feed gas composed of hydrocarbons for film formation; IBD (Ion Beam Deposition), which uses electrons released from a filament to ionize the feed gas for film formation; and FCVA (Filtered Cathodic Vacuum Arc), which uses a solid carbon target for film formation without using a feed gas.

[0099] It should be noted that, in this embodiment, during the laminate formation process, an adhesion layer, a soft magnetic substrate layer, a seed layer, or an orientation control layer may also be formed between the substrate 111 and the magnetic recording layer 112.

[0100] In this embodiment, when the laminate 11 has a plurality of stacked magnetic recording layers 112, the laminate forming process may include forming non-magnetic recording layers between the magnetic recording layers 112.

[0101] Next, a lubricant is applied to the surface of the laminate 11 to form a lubricating layer 12 (a film composed of lubricant) (coating process). Thus, a multilayer 11A with a lubricating layer 12 formed on the surface of the laminate 11 can be obtained.

[0102] The lubricant can be applied using conventional coating methods, such as dip coating, spin coating, and vapor deposition. It should be noted that, as described above, the finishing process can be performed either before or after the coating process. When the finishing process is performed before the coating process, the multilayer 11A is a laminate 11 on which the lubricant layer 12 is not formed. On the other hand, when the finishing process is performed after the coating process, the multilayer 11A is formed by laminating the lubricant layer 12 onto the laminate 11.

[0103] Next, as Figure 3 As shown, the surface of the multilayer body 11A is polished using the polishing belt 20 (polishing process).

[0104] Finishing is performed by using an abrasive belt 20 wound into a roll shape. The abrasive belt 20, which is supplied in a roll shape, is pressed onto the surface of the multilayer body 11A and scraped.

[0105] Here, in this embodiment, the polishing tape 20, wound into a cylindrical shape and used in the finishing process, is a polishing tape whose free abrasive grains have been removed by rewinding. That is, as described above, when the polishing tape 20 is made into a cylindrical shape, free abrasive grains are generated due to the pressure generated by winding and tightening, and these free abrasive grains become the cause of defective products. In this embodiment, the free abrasive grains are removed by rewinding the cylindrical polishing tape 20 before use. Therefore, the generation of defective products of the multilayer 11A caused by free abrasive grains can be suppressed, thereby improving the productivity of the magnetic recording medium 1.

[0106] Figure 4 This is an enlarged cross-sectional view showing an example of the abrasive belt 20 used during finishing. (See attached image.) Figure 4 As shown, the grinding belt 20 can grind the multilayer 11A by sliding the grinding surface S relative to the surface of the multilayer 11A.

[0107] The abrasive belt 20 has an abrasive material layer 22 on the support 21. The abrasive material layer 22 includes abrasive grains 221 and an adhesive 222, which bonds the abrasive grains 221 to each other and to the support 21 so that the abrasive grains 221 are fixed on the abrasive material layer 22.

[0108] The material constituting the support 21 is not particularly limited. For example, various resins such as polyethylene terephthalate can be used as materials constituting the support 21.

[0109] Abrasive grains 221 can be used as abrasive materials contained in the abrasive belt 20. Abrasive grains 221 can be, for example, particles including chromium oxide, α-alumina, silicon carbide, non-magnetic iron oxide, diamond, γ-alumina, α,γ-alumina, fused alumina, corundum, synthetic diamond, etc. Abrasive grains 221 can also be particles composed of these materials. One type can be used alone, or two or more can be combined appropriately.

[0110] There are no particular limitations on the adhesive 222. For example, thermosetting resins, thermoplastic resins, photosensitive resins, etc., can be used as adhesive 222. One type of resin can be used alone, or two or more types can be used in combination.

[0111] As mentioned above, the grinding belt 20 is relatively long, therefore... Figure 1 As shown, the grinding belt is supplied in a wound-up cylindrical state and is used on the roller of the finishing device in a wound-up cylindrical state.

[0112] As described above, when the grinding belt 20 is rolled into a cylindrical shape, free abrasive grains are generated inside the drum due to the pressure generated by the winding and tightening. Here, if the pressure generated by the winding and tightening is very large, the abrasive grains 221 adhering to the support 21 may themselves become free, but it is generally believed that the weaker abrasive grains 221 adhering to the support 21 or the abrasive grains 221 adhering to the adhering abrasive grains 221 will become free. It is difficult to completely remove such free abrasive grains 221 during the manufacturing process of the grinding belt 20, and most of them are likely to be generated after the grinding belt 20 is manufactured, that is, after the grinding belt 20 is wound into a cylindrical shape.

[0113] In this embodiment, since the free abrasive grains 221 are removed by rewinding the cylindrical abrasive belt 20 before use, the generation of defective products caused by the free abrasive grains 221 can be suppressed. Here, although the abrasive belt 20 becomes cylindrical again by rewinding, the pressure generated by the winding and tightening has already been applied to the abrasive belt 20, so even if it is rewound, the generation of free abrasive grains 221 can be suppressed.

[0114] The rewinding speed of the grinding belt 20 is preferably about 1 to 20 m / min. Since the rewinding of the grinding belt 20 will subject the surface of the grinding belt 20 to wind pressure, the free abrasive particles 221 on the surface of the grinding belt 20 can be removed by the wind pressure.

[0115] Furthermore, in this embodiment, such as Figure 5 As shown, it is preferable to use gas to blow away the free abrasive particles 221 in the cylindrical abrasive belt 20. By using such a method, the free abrasive particles 221 can be removed more effectively and reliably.

[0116] exist Figure 5 In this process, the grinding belt 20 is placed on the supply-side reel 31, and the grinding belt 20 is guided by the guide roller 32 while being wound by the winding reel 33. Then, both sides of the grinding belt 20 are cleaned by gas ejected from a pair of gas nozzles 34 during its travel. In order to prevent the re-adhesion of free abrasive particles 221 caused by static electricity, it is preferable to remove the free abrasive particles 221 in an anti-static atmosphere.

[0117] Furthermore, in this embodiment, such as Figure 6 As shown, free abrasive particles 221 are preferably removed by bringing another belt 44 into contact with the surface of the abrasive belt 20, thereby causing the free abrasive particles 221 to be adsorbed onto the other belt 44. By using such a method, free abrasive particles 221 can be removed more effectively and reliably.

[0118] exist Figure 6In this process, an abrasive belt 20 is placed on a reel 41 on the abrasive belt supply side, and the abrasive belt 20 is guided by a guide roller 42 while being wound by an abrasive belt winding reel 43. Then, the surface of the abrasive belt 20 comes into contact with another belt 44 during its travel, thereby removing free abrasive particles 221. In order to facilitate the adsorption of free abrasive particles, it is preferable to make the contact surface of the other belt 44 electrified or to give it adhesive properties. The other belt 44 is placed on a reel 45 on the other belt supply side, and comes into contact with the surface of the abrasive belt 20 by being guided by a guide roller 42, and is then wound by a reel 46.

[0119] In the finishing process, a method can be used to press a belt containing abrasive material (abrasive belt 20) onto the surface of the multilayer body 11A and scrape it. The finishing method and finishing apparatus will be described in detail with reference to the figures.

[0120] Figure 7 This figure shows an example of a finishing apparatus used in a process of finishing the surface of a multilayer body 11A using an abrasive belt 20. Figure 7 As shown, the finishing apparatus 50 includes a set of grinding belts 20 (hereinafter also referred to as "a set of grinding belts 20A and 20B"), a rotating support component 51, and a belt moving component 52.

[0121] A set of grinding belts 20A and 20B are supplied from the first grinding belt supply side reel 53A and the second grinding belt supply side reel 53B respectively in a cylindrical state, and then wound in a cylindrical state by the first grinding belt winding reel 54A and the second grinding belt winding reel 54B.

[0122] In the finishing apparatus 50, by arranging a set of grinding belts 20A and 20B relative to each other to clamp the multilayer body 11A from its two sides, the two sides of the multilayer body 11A can be finished simultaneously and effectively.

[0123] With the rotating support member 51 supporting the central opening of the multilayer body 11A, the multilayer body 11A is rotated in the circumferential direction (in the direction of arrow r).

[0124] The moving part 52 presses a set of abrasive belts 20A and 20B onto two surfaces of the rotating multilayer body 11A in the direction of arrow F, while moving the set of abrasive belts 20A and 20B relative to each other in the radial direction of the multilayer body 11A.

[0125] In addition, the moving part 52 has a pair of grinding belt pressing parts 521 and a pair of grinding belt traveling systems 522, the pair of grinding belt pressing parts 521 being configured to clamp the multilayer body 11A from its two sides via a set of grinding belts 20A and 20B.

[0126] A pair of grinding belt pressing components 521 includes a first grinding belt pressing component 521A and a second grinding belt pressing component 521B. A pair of grinding belt traveling systems 522 includes a first grinding belt traveling system 522A and a second grinding belt traveling system 522B.

[0127] That is, the belt moving member 52 has a first grinding belt traveling system 522A and a first grinding belt pressing member 521A disposed on one side through the multilayer body 11A, and a second grinding belt traveling system 522B and a second grinding belt pressing member 521B disposed on the other side.

[0128] The first grinding belt traveling system 522A has first guide rollers 523A-1 to 523A-6 to make the grinding belt 20A travel in the direction of arrow Ra.

[0129] The second grinding belt traveling system 522B has second guide rollers 523B-1 to 523B-6 to make the grinding belt 20B travel in the direction of arrow Rb.

[0130] As described above, the manufacturing method of the magnetic recording medium according to this embodiment includes a finishing process, in which an abrasive belt 20, supplied in a wound roll state, is pressed onto the surface of the multilayer 11A and scraped. At this time, the abrasive belt 20, in its wound roll state, is pre-rewound to remove free abrasive grains. Therefore, circumferential damage caused by free abrasive grains and the adhesion of free abrasive grains as foreign matter or other contaminants can be suppressed on the surface of the multilayer 11A. Therefore, according to the manufacturing method of the magnetic recording medium according to this embodiment, the occurrence rate of defective products in the magnetic recording medium 1 can be reduced in the finishing process, thereby improving the productivity of the magnetic recording medium 1.

[0131] As described above, the magnetic recording medium 1 manufactured using the manufacturing method of the magnetic recording medium according to this embodiment has almost no circumferential damage and contamination on its surface, thus improving quality reliability. Since the magnetic recording medium 1 can suppress defects in writing and reading and maintain a high recording density, it can be appropriately used in magnetic recording and reproducing apparatuses. As long as a magnetic recording medium manufactured using the manufacturing method of the magnetic recording medium according to this embodiment is available, the form of the magnetic recording and reproducing apparatus is not particularly limited; it can also be a magnetic recording and reproducing apparatus that uses a heat-assisted recording method to record magnetic information on the magnetic recording medium, etc.

[0132] As described above, the embodiments have been illustrated, but these embodiments are merely examples and do not limit the present invention. The embodiments described above can be implemented in various other ways, and various combinations, omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments described above and their variations are included within the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

[0133] [Example]

[0134] The following describes this implementation method in detail based on the embodiments, but these embodiments do not constitute a limitation on this implementation method.

[0135] <Example 1>

[0136] [Preparation of abrasive belts]

[0137] The abrasive belt uses Al₂O₃ (manufactured by Mipox) with a particle size of 0.2 μm as the abrasive material. The belt is 12.6 mm wide and 100 m long, rolled into a cylindrical shape. Through the use of… Figure 5 The apparatus shown rewinds the abrasive belt, removing loose abrasive particles. At this time, gas is not ejected from gas nozzle 34, and the abrasive belt travels at a speed of 10 m / min. Rewinding is performed in a de-electrified environment.

[0138] [Fabrication of Magnetic Recording Media]

[0139] The cleaned glass substrate (HOYA, 2.5-inch) was placed in the deposition chamber of a DC magnetron sputtering apparatus (ANELVA C-3040). The deposition chamber was evacuated until a vacuum of 1×10⁻⁶ was achieved. -5 Pa. Then, by sputtering, a 10 nm thick adhesion layer is formed on the glass substrate using a Cr target.

[0140] Then, a soft magnetic substrate layer is formed on the adhesion layer by sputtering. As the soft magnetic substrate layer, a first soft magnetic recording layer, an intermediate layer, and a second soft magnetic recording layer are formed sequentially. First, a first soft magnetic recording layer with a thickness of 25 nm is formed using a target material Co-20Fe-5Zr-5Ta {Fe content 20 atomic%, Zr content 5 atomic%, Ta content 5 atomic%, balance Co} at a substrate temperature below 100°C. Next, an intermediate layer with a thickness of 0.7 nm composed of Ru is formed. Then, a second soft magnetic recording layer with a thickness of 25 nm composed of Co-20Fe-5Zr-5Ta is formed.

[0141] Next, using a target material Ni-6W {W content is 6 atomic%, and the residue is Ni}, a seed layer with a thickness of 5 nm is formed on a soft magnetic substrate by sputtering.

[0142] Then, a Ru layer with a thickness of 10 nm is formed on the seed layer by sputtering as the first orientation control layer, wherein the sputtering pressure is 0.8 Pa. Next, a Ru layer with a thickness of 10 nm is formed on the first orientation control layer by sputtering as the second orientation control layer, wherein the sputtering pressure is 1.5 Pa.

[0143] Next, a first magnetic recording layer, consisting of 91(Co15Cr16Pt)-6(SiO2)-3(TiO2) {Cr content 15 atomic%, Pt content 16 atomic%, balance 91 mol% Co alloy, 6 mol% SiO2, 3 mol% TiO2}, was formed on the second orientation control layer with a layer thickness of 9 nm by sputtering. The sputtering pressure here was 2 Pa.

[0144] Next, a non-magnetic recording layer consisting of 88(Co30Cr)-12(TiO2) {Cr content is 30 atomic%, with the balance being 88 mol% Co alloy and 12 mol% TiO2} is formed on the first magnetic recording layer with a layer thickness of 0.3 nm by sputtering.

[0145] Then, a second magnetic recording layer, consisting of 92(Co11Cr18Pt)-5(SiO2)-3(TiO2) {Cr content 11 atomic%, Pt content 18 atomic%, balance 92 mol% Co alloy, 5 mol% SiO2, 3 mol% TiO2}, was formed on the non-magnetic recording layer with a thickness of 6 nm by sputtering. The sputtering pressure here was 2 Pa.

[0146] Then, a non-magnetic recording layer composed of Ru was formed on the second magnetic recording layer with a layer thickness of 0.3 nm by sputtering.

[0147] Next, a third magnetic recording layer was formed on the non-magnetic recording layer by sputtering using a target material composed of Co-20Cr-14Pt-3B {Cr content is 20 atomic%, Pt content is 14 atomic%, B content is 3 atomic%, and the balance is Co}, with a layer thickness of 7 nm and a sputtering pressure of 0.6 Pa.

[0148] On the surface of the third magnetic recording layer, vaporized toluene was used as the feed gas, and a hydrogenated carbon film was formed as a protective layer by ion beam evaporation. During the formation of the hydrogenated carbon film, the flow rate of the feed gas supplied to the deposition chamber was initially set to 2.9 SCCM, and the reaction pressure was set to 0.2 Pa. The cathode power, serving as the excitation source for the feed gas, was set to 225 W (22.5 V AC, 10 A). Then, the voltage between the cathode electrode and the anode electrode covering the cathode electrode was set to 75 V, the current to 1650 mA, the ion acceleration voltage to 200 V, the current to 180 mA, and the deposition time to 1.5 seconds, forming a hydrogenated carbon film with a thickness of 3.5 nm. After the hydrogenated carbon film was formed, the feed gas supply was stopped, and the deposition chamber was vented for 2 seconds.

[0149] Next, nitrogen gas was supplied to the film-forming chamber at a flow rate of 2 SCCM and a reaction pressure of 5 Pa. Then, nitrogen ions formed from the nitrogen gas were irradiated onto the surface of the carbon hydride film, exposing it to nitrogen plasma. The cathode power was 128 W (16V AC, 8A), the voltage between the cathode and anode electrodes was 75V, the current was 1000 mA, the ion acceleration voltage was 200V, the current was 90 mA, and the treatment time was 1 second. This process dehydrogenated and nitrided the surface of the carbon hydride film.

[0150] Next, a lubricant (D5OH(XS), manufactured by Matsumura Petroleum Research Institute Co., Ltd.) is applied to the surface of the protective layer using an impregnation method, forming a lubricating layer composed of lubricant, with a thickness of approximately

[0151] Next, the surface of the laminate with the lubricating layer is finished using a polishing tape rewound as described above. The finishing conditions are set to a lamination rotation speed of 2000 rpm and a processing time of 7 seconds. Through the finishing process, a magnetic recording medium with a finished lubricating layer laminated on the surface of the laminate is obtained.

[0152] [Measurement of TA count]

[0153] The prepared magnetic recording medium is optically inspected to exclude those with large scratches and particles. Next, to remove foreign matter adhering to the magnetic recording medium, after processing with an optical sizing head, a slip evaluation using a sliding head is performed. Slip evaluation is an assessment method that detects vibrations generated when the magnetic recording medium collides with protrusions on its surface using an AE sensor mounted on the sliding head. The TA count is evaluated for magnetic recording media that pass the slip evaluation. The TA count is used for TA count evaluation. The TA count evaluation is a method that detects fluctuations in the signal waveform reproduced from the MR head based on the scraping heat generated when the MR head collides with protrusions on the surface of the magnetic recording medium (i.e., thermal asperity (TA)), and evaluates the smoothness of the magnetic recording medium's surface based on the amount of signal generated (TA count). A smaller TA count indicates a higher smoothness of the magnetic recording medium's surface. In a 100m long polishing tape, the average value of each surface of 100 magnetic recording media that underwent polishing treatment near 20m from the outermost rolled-up end of the polishing tape was calculated, as well as the average value of each surface of 100 magnetic recording media that underwent polishing treatment near 80m from the outermost rolled-up end of the polishing tape. The area up to approximately 20m from the outermost rolled-up end of the polishing tape is located on the outer side of the polishing tape, and the area from 20m to 100m along the length of the polishing tape is located on the inner side of the polishing tape. The evaluation results are shown in Table 1.

[0154] <Examples 2, 3, and Comparative Example 1>

[0155] Except for the following changes to the preparation of the polishing tape, the magnetic recording medium was manufactured and the TA count was measured in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0156] [Example 2]

[0157] from Figure 5 The device shown injects nitrogen gas through gas nozzle 34, and otherwise prepares the grinding belt in the same manner as in Example 1.

[0158] [Example 3]

[0159] By using Figure 6 The apparatus shown is rewound to remove free abrasive particles. A charged polyethylene belt is used as another belt in contact with the grinding belt, and the belt travels at a speed of 10 m / min. The grinding belt is de-energized and rewound. Otherwise, the grinding belt is prepared in the same manner as in Example 1.

[0160] [Comparative Example 1]

[0161] Except for not rewinding, the grinding tape was prepared in the same manner as in Example 1.

[0162]

[0163]

[0164] As can be seen from Table 1, in Comparative Example 1, the TA count differed between the inner and outer sides of the polishing belt roll after finishing. This is believed to be due to the difference in the amount of free abrasive grains generated on the inner and outer sides of the roll caused by the pressure generated during winding and tightening within the polishing belt roll. On the other hand, in Examples 1-3, the TA count was the same on both the inner and outer sides of the polishing belt roll. This is believed to be because the free abrasive grains on the inner and outer sides of the roll were removed by rewinding the polishing belt roll.

[0165] Therefore, by rewinding the spool of the polishing tape during its preparation, the incidence of defective products in the finishing process of the magnetic recording medium to be manufactured can be reduced, thereby improving the productivity of the magnetic recording medium.

Claims

1. A method for manufacturing a magnetic recording medium, comprising: The finishing process involves using an abrasive material to finish the surface of the laminate, in which a magnetic recording layer and a protective layer are sequentially stacked on a substrate. The finishing process includes: The long abrasive strip is used while wound into a cylindrical shape, and the abrasive strip supplied from the wound cylindrical shape is pressed against the surface of the laminate to scrape. The abrasive strip has abrasive grains attached to the support as the abrasive material. The grinding belt, which has had free abrasive grains removed by rewinding, is used as the grinding belt wound into the cylindrical shape.

2. The method for manufacturing a magnetic recording medium according to claim 1, wherein, The free abrasive grains are abrasive grains that are freed from the support of the grinding belt.

3. The method for manufacturing a magnetic recording medium according to claim 1 or 2, wherein, The free abrasive particles are removed by purging with gas.

4. The method for manufacturing a magnetic recording medium according to claim 1 or 2, wherein, The free abrasive particles are removed by bringing another belt into contact with the surface of the abrasive belt and causing the free abrasive particles to be adsorbed onto the other belt.

5. A method for manufacturing a magnetic recording medium according to claim 1 or 2, comprising: The lubricating layer formation process involves forming a lubricating layer on the surface of the laminate. In the finishing process, the surface of the laminate on which the lubricating layer is formed is finished using the abrasive material.

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