# US 6,296,917 B1 · Magnetic disk and magnetic recording/reproduction apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,296,917 B1 - Document ID: US6296917B1 - Status: Granted - Kind: B1 - Application number: 09/051,711 - Filed: 1998-04-17 - Granted: 2001-10-02 - Earliest claimed: 1998-04-17 - Assignees: Hitachi, Ltd. - Inventors: Takayuki Nakakawaji; Mitsuyoshi Shouji; Tomoe Takamura; Hiroshi Sasaki; Shuji Imazeki; Yutaka Ito - Web page: https://patentgrep.com/patent/US6296917B1 ## CPC - G11B 5/7257: {Perfluoropolyether lubricant} - G11B 5/7266: {comprising a lubricant over the inorganic carbon coating} - Y10S 428/90: Magnetic feature - Y10T 428/24355: Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.] - Y10T 428/30: Self-sustaining carbon mass or layer with impregnant or other layer - Y10T 428/3154: Of fluorinated addition polymer from unsaturated monomers - Y10T 428/31544: Addition polymer is perhalogenated - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A lubricating film is provided for a magnetic disk having a data region and a CSS region formed on its surface. The lubricating film ensures low stiction and good resistance to contact sliding in the data region and also ensures good CSS durability in the CSS region. Therefore, it is possible to provide a magnetic disk and a magnetic recording/reproducing device which do not cause problems with sliding between the magnetic head and the magnetic disk while the apparatus is running normally and even when the apparatus stops accidentally. The lubricating film formed in the data region of the magnetic disk is firmly fixed to the surface of the magnetic disk and is hardly liable to stiction. In addition, it is thick enough to ensure good durability even in the case of contact sliding. The lubricating film formed in the CSS region is composed of a lubricant which is firmly fixed to the surface of the magnetic disk and another lubricant which is weakly fixed to the surface of the magnetic disk; therefore, it is superior in CSS durability. This contributes to the highly reliable magnetic disk and magnetic recording/reproducing device. ## Claims ### Claim 1 A magnetic disk, comprising: a substrate; a magnetic layer provided over said substrate; a protective layer provided over said magnetic layer; and a lubricating layer provided on said protective layer; wherein said magnetic disk comprises a CSS region on which a head slider is positioned when said magnetic disk starts and stops rotating and a data region over which the head slider is positioned while said magnetic disk is rotating for recording or reproducing information on said data region; wherein said lubricating layer comprises at least a first lubricant and a second lubricant fixed to said protective layer, wherein said first lubricant is more firmly fixed to said protective layer than said second lubricant and wherein said lubricating layer in said CSS region comprises not less than 10% of said second lubricant and said lubricating layer in said data region comprises less than 10% of said second lubricant. ### Claim 2 (depends on 1) The magnetic disk according to claim 1, wherein said first lubricant chemically reacts with said protective layer. ### Claim 3 (depends on 1) The magnetic disk according to claim 1, wherein said lubricating layer includes at least one member selected from the group consisting of perfluoropolyether compounds expressed by the formulae (I) to (III) below, R1—X—(CF2CF2O)m—(CF2O)n—X—R2 (I) F(CF2CF2CF2—O)n—C2F4—X—R3 (II) F—(CF(CF3)—CF2—O)n—CF(CF3)—X—R4 (III) wherein m and n are integers; R1, R2, R3 and R4 are hydrocarbon chains; and X is a divalent binding group. ### Claim 4 (depends on 1) The magnetic disk according to claim 1, wherein said first lubricant includes at least one member selected from the group consisting of perfluoropolyether compounds expressed by the formulae (IV) and (VI) below, (C2H5O)3Si—C3H6—NHCO—(CF2CF2O)m—(CF2O)n—CONH—C3H6—Si(OC2H5)3 (VI) F(CF2CF2CF2—O)n—C2F4—CONH—C3H6—Si(OC2H5)3 (IV) and said second lubricant includes at least one member selected from the group consisting of perfluoropolyether compounds expressed by the formulae (VIII) and (XI) below, F(CF2CF2CF2—O)n—C2F4—CH2OH (VIII) F(CF2CF2CF2O)n—C2F4—COO—+NH3—C6H4—O—C6H5 (XI) where m and n are integers. ### Claim 5 (depends on 1) The magnetic disk according to claim 1, wherein the CSS region has a surface roughness greater than or equal to Ra 10 nm at the place where the magnetic head slider is positioned when the magnetic disk starts and stops rotating, and the data region has a surface roughness smaller than or equal to Ra 3 mn at the place where the magnetic head slider is positioned while the magnetic disk is rotating. ### Claim 6 A method for producing a magnetic disk having a lubricating layer on a protective layer of the disk surface, a CSS region on which a head slider is positioned when the magnetic disk starts and stops rotating and a data region over which the head is positioned and performs recording and reproducing while the disk is rotating, comprising: carrying out the following steps (a), (b), and (c) in the data region; and carrying out the following steps (a) and (b) in the CSS region, where the steps (a), (b), and (c) are: (a): coating the disk surface with a lubricant (b): performing a heat treatment or UV treatment (c): washing the disk surface. ### Claim 7 (depends on 6) The method for producing a magnetic disk according to claim 6, comprising the steps of: carrying out the steps (a), and (b), over all of the disk surface; and then carrying out the step (a) over all the disk surface; and then carrying out the step only in the data region. ### Claim 8 (depends on 7) The method for producing a magnetic disk according to claim 7, wherein, the lubricant which is first coated over all the disk surface comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (IV) below, and F(CF2CF2CF2—O)n—C2F4—CONH—C3H6—Si(OC2H5)3 (IV), and the lubricant that is secondly coated all over the disk surface comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (XI) below F(CF2CF2CF2O)n—C2F4—COO—+NH3—C6H4—O—C6H5 (XI) where m and n are integers. ### Claim 9 (depends on 6) The method for producing a magnetic disk according to claim 6, comprising carrying out the steps (a), (b), and (c) over all of the disk surface; and then carrying out the step (a) over all of the disk surface; and then carrying out the step (c) and then (a) only in the data region. ### Claim 10 (depends on 9) The method for producing a magnetic disk according to claim 9, wherein the lubricant that is first coated over all of the disk surface comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (VI) below, (C2H5O)3Si—C3H6—NHCO—(CF2CF2O)m—(CF2O)n—CONH—C3H6—Si(OC2H5)3 (VI) the lubricant which is secondly coated over all of the disk surface comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (VIII) below, and F(CF2CF2CF2—O)n—C2F4—CH2OH (VIII) the lubricant that is thirdly coated only in the data region comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (VI) below (C2H5O)3Si—C3H6—NHCO—(CF2CF2O)m—(CF2O)n—CONH—C3H6—Si(OC2H5)3 (VI) where m and n are integers. ### Claim 11 (depends on 6) The method for producing a magnetic disk according to claim 6, comprising carrying out the steps (a), (b), and (c) over all of the disk surface; and then carrying out the step (a) over all of the disk surface; and then carrying out the steps (b) and then (c) only in the data region. ### Claim 12 (depends on 1) The method for producing a magnetic disk according to claim 1, wherein, the lubricant that is first coated over all of the disk surface comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (XIII) below, the lubricant that is secondly coated over all of the disk surface comprises a compound selected from the group consisting of perfluoropolyether compounds expressed by the formula (VII) below C6H5—O—C6H4—H3N+—OCO—(CF2CF2O)m—(CF2O)n—COO—+NH3—C6H4—O—C6H5 (VII) where m and n are integers. ### Claim 13 (depends on 6) The method for producing a magnetic disk according to claim 6, further comprising drying the lubricant in the data region and the CSS region after the step (a). ### Claim 14 (depends on 6) The method for producing a magnetic disk according to claim 6, wherein the CSS region is formed to have a surface roughness greater than or equal to Ra 10 nm at the place where the magnetic head slider is positioned when the magnetic disk starts and stops rotating, and the data region is formed to have a surface roughness smaller than or equal to Ra 3 nm at the place where the magnetic head slider is positioned while the magnetic disk is rotating. ### Claim 15 (depends on 6) The method for producing a magnetic disk according to claim 6, wherein the step (c) is carried out with a perfluorocarbon solvent.