WO2024024781A1 - 含フッ素エーテル化合物、磁気記録媒体用潤滑剤および磁気記録媒体 - Google Patents

含フッ素エーテル化合物、磁気記録媒体用潤滑剤および磁気記録媒体 Download PDF

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WO2024024781A1
WO2024024781A1 PCT/JP2023/027183 JP2023027183W WO2024024781A1 WO 2024024781 A1 WO2024024781 A1 WO 2024024781A1 JP 2023027183 W JP2023027183 W JP 2023027183W WO 2024024781 A1 WO2024024781 A1 WO 2024024781A1
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formula
group
compound
represented
fluorine
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English (en)
French (fr)
Japanese (ja)
Inventor
優 丹治
剛 加藤
大輔 柳生
直也 福本
夏実 吉村
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Resonac Corp
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Resonac Corp
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Priority to CN202380037136.7A priority Critical patent/CN119137092A/zh
Priority to US18/861,341 priority patent/US20250349317A1/en
Priority to JP2024537745A priority patent/JP7754327B2/ja
Publication of WO2024024781A1 publication Critical patent/WO2024024781A1/ja
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/72—Protective coatings, e.g. anti-static or antifriction
    • G11B5/725—Protective coatings, e.g. anti-static or antifriction containing a lubricant, e.g. organic compounds
    • G11B5/7253—Fluorocarbon lubricant
    • G11B5/7257—Perfluoropolyether lubricant
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C233/00—Carboxylic acid amides
    • C07C233/01—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms
    • C07C233/16—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms having the nitrogen atom of at least one of the carboxamide groups bound to a carbon atom of a hydrocarbon radical substituted by singly-bound oxygen atoms
    • C07C233/17—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms having the nitrogen atom of at least one of the carboxamide groups bound to a carbon atom of a hydrocarbon radical substituted by singly-bound oxygen atoms with the substituted hydrocarbon radical bound to the nitrogen atom of the carboxamide group by an acyclic carbon atom
    • C07C233/18—Carboxylic acid amides having carbon atoms of carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms having the nitrogen atom of at least one of the carboxamide groups bound to a carbon atom of a hydrocarbon radical substituted by singly-bound oxygen atoms with the substituted hydrocarbon radical bound to the nitrogen atom of the carboxamide group by an acyclic carbon atom having the carbon atom of the carboxamide group bound to a hydrogen atom or to a carbon atom of an acyclic saturated carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C235/00—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by oxygen atoms
    • C07C235/42—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by oxygen atoms having carbon atoms of carboxamide groups bound to carbon atoms of six-membered aromatic rings and singly-bound oxygen atoms bound to the same carbon skeleton
    • C07C235/44—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by oxygen atoms having carbon atoms of carboxamide groups bound to carbon atoms of six-membered aromatic rings and singly-bound oxygen atoms bound to the same carbon skeleton with carbon atoms of carboxamide groups and singly-bound oxygen atoms bound to carbon atoms of the same non-condensed six-membered aromatic ring
    • C07C235/58—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by oxygen atoms having carbon atoms of carboxamide groups bound to carbon atoms of six-membered aromatic rings and singly-bound oxygen atoms bound to the same carbon skeleton with carbon atoms of carboxamide groups and singly-bound oxygen atoms bound to carbon atoms of the same non-condensed six-membered aromatic ring with carbon atoms of carboxamide groups and singly-bound oxygen atoms, bound in ortho-position to carbon atoms of the same non-condensed six-membered aromatic ring
    • C07C235/60—Carboxylic acid amides, the carbon skeleton of the acid part being further substituted by oxygen atoms having carbon atoms of carboxamide groups bound to carbon atoms of six-membered aromatic rings and singly-bound oxygen atoms bound to the same carbon skeleton with carbon atoms of carboxamide groups and singly-bound oxygen atoms bound to carbon atoms of the same non-condensed six-membered aromatic ring with carbon atoms of carboxamide groups and singly-bound oxygen atoms, bound in ortho-position to carbon atoms of the same non-condensed six-membered aromatic ring having the nitrogen atoms of the carboxamide groups bound to hydrogen atoms or to acyclic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
    • C07C255/15—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms containing cyano groups and singly-bound oxygen atoms bound to the same unsaturated acyclic carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/49—Carboxylic acid nitriles having cyano groups bound to carbon atoms of six-membered aromatic rings of a carbon skeleton
    • C07C255/54—Carboxylic acid nitriles having cyano groups bound to carbon atoms of six-membered aromatic rings of a carbon skeleton containing cyano groups and etherified hydroxy groups bound to the carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C43/00—Ethers; Compounds having groups, groups or groups
    • C07C43/02—Ethers
    • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
    • C07C43/04—Saturated ethers
    • C07C43/13—Saturated ethers containing hydroxy or O-metal groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/002—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from unsaturated compounds
    • C08G65/005—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from unsaturated compounds containing halogens
    • C08G65/007—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from unsaturated compounds containing halogens containing fluorine
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/04—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers only
    • C08G65/22—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring
    • C08G65/223—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring containing halogens
    • C08G65/226—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring containing halogens containing fluorine
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
    • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
    • C08G65/331—Polymers modified by chemical after-treatment with organic compounds containing oxygen
    • C08G65/3311—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing a hydroxy group
    • C08G65/3312—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing a hydroxy group acyclic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
    • C08G65/32—Polymers modified by chemical after-treatment
    • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
    • C08G65/331—Polymers modified by chemical after-treatment with organic compounds containing oxygen
    • C08G65/3311—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing a hydroxy group
    • C08G65/3314—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing a hydroxy group cyclic
    • C08G65/3315—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing a hydroxy group cyclic aromatic
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M107/00—Lubricating compositions characterised by the base-material being a macromolecular compound
    • C10M107/38—Lubricating compositions characterised by the base-material being a macromolecular compound containing halogen
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/72—Protective coatings, e.g. anti-static or antifriction
    • G11B5/725—Protective coatings, e.g. anti-static or antifriction containing a lubricant, e.g. organic compounds
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2650/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
    • C08G2650/28—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule characterised by the polymer type
    • C08G2650/46—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule characterised by the polymer type containing halogen
    • C08G2650/48—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule characterised by the polymer type containing halogen containing fluorine, e.g. perfluropolyethers
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
    • C10M2213/04—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions obtained from monomers containing carbon, hydrogen, halogen and oxygen
    • C10M2213/043—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions obtained from monomers containing carbon, hydrogen, halogen and oxygen used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
    • C10M2213/06—Perfluoro polymers
    • C10M2213/0606—Perfluoro polymers used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/04—Molecular weight; Molecular weight distribution
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/18—Electric or magnetic purposes in connection with recordings on magnetic tape or disc
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
    • C10N2050/023—Multi-layer lubricant coatings
    • C10N2050/025—Multi-layer lubricant coatings in the form of films or sheets

Definitions

  • the present invention relates to a fluorine-containing ether compound, a lubricant for magnetic recording media, and a magnetic recording medium.
  • magnetic recording media in which a recording layer is formed on a substrate, and a protective layer made of carbon or the like is formed on the recording layer.
  • the protective layer protects the information recorded on the recording layer and improves the sliding properties of the magnetic head.
  • simply providing a protective layer on the recording layer does not provide sufficient durability of the magnetic recording medium. For this reason, a lubricant is generally applied to the surface of the protective layer to form a lubricant layer.
  • a lubricant used when forming a lubricant layer of a magnetic recording medium for example, a compound having a polar group such as a hydroxyl group or an amino group at the end of a fluorine-based polymer having a repeating structure containing -CF 2 - is used. It has been proposed that it contains
  • Patent Document 1 and Patent Document 2 describe a divalent linkage in which methylene groups (-CH 2 -) are bonded to both ends of a glycerin structure (-O-CH 2 -CH(OH)-CH 2 -O-).
  • a fluorine-containing ether compound has a skeleton in which two perfluoropolyether chains are bonded via a group, and a terminal group, which is an organic group having a polar group, is bonded to both ends of the skeleton via a methylene group.
  • Patent Documents 3 to 5 describe a methylene group (-CH 2 -) and a group in which one of the hydrogen atoms of the methylene group is substituted with a hydroxyl group (-CH(OH)-), and has two hydroxyl groups. It has a skeleton in which two perfluoropolyether chains are bonded via a divalent linking group, and a terminal group, which is an organic group having a polar group, is bonded to both ends of the skeleton via a methylene group. Fluorine ether compounds are disclosed.
  • Patent Document 6 describes a divalent group containing a methylene group (-CH 2 -) and a group in which one of the hydrogen atoms of the methylene group is replaced with a hydroxyl group (-CH(OH)-), and having two hydroxyl groups. It has a skeleton in which two or three perfluoropolyether chains are bonded through a linking group, and a terminal group, which is an organic group having a polar group, is bonded to both ends of the skeleton via a methylene group.
  • a fluorine-containing ether compound is disclosed.
  • Patent Document 7 and Patent Document 8 contain a methylene group (-CH 2 -) and a group in which one of the hydrogen atoms of the methylene group is replaced with a hydroxyl group (-CH(OH)-), and the hydroxyl group is replaced with one hydroxyl group. It has a skeleton in which three perfluoropolyether chains are bonded via a divalent linking group, and terminal groups, which are organic groups having a hydroxyl group or a polar group, are bonded to both sides of the skeleton via methylene groups.
  • a fluorine-containing ether compound is disclosed.
  • the flying height of the magnetic head In magnetic recording and reproducing devices, it is required to further reduce the flying height of the magnetic head.
  • the flying height of the magnetic head is reduced, the magnetic head and the substrate are more likely to collide. That is, the flying stability of the magnetic head tends to decrease.
  • pickup may occur in which the fluorine-containing ether compound in the lubricating layer adheres to the magnetic head.
  • the present invention has been made in view of the above circumstances, and can form a lubricant layer that has excellent flying stability and can suppress pickup, and can be suitably used as a lubricant material for magnetic recording media.
  • the purpose of the present invention is to provide a fluorine-containing ether compound.
  • Another object of the present invention is to provide a lubricant for a magnetic recording medium that includes the fluorine-containing ether compound of the present invention, has good flying stability, and can form a lubricant layer that is highly effective in suppressing pickup.
  • Another object of the present invention is to provide a magnetic recording medium that has a lubricating layer containing the fluorine-containing ether compound of the present invention, has good flying stability of a magnetic head, and is highly effective in suppressing pickup.
  • a first aspect of the present invention provides the following fluorine-containing ether compound.
  • a fluorine-containing ether compound represented by the following formula (1).
  • x represents an integer of 1 to 2;
  • R 2 is a perfluoropolyether chain;
  • (x+1) R 2 may be partly or completely the same; , may be different from each other;
  • R 3 is a divalent linking group having a hydroxyl group; at least one of the x R 3s is represented by the following formula (2-1) or (2-2).
  • x is 2
  • the two R 3s may be the same or different;
  • R 1 and R 4 have two to two polar groups.
  • the fluorine-containing ether compound of the first aspect of the present invention preferably has the characteristics described in [2] to [9] below. It is also preferable to arbitrarily combine two or more of the features described in [2] to [9] below.
  • R 1 and R 4 in the formula (1) each independently contain at least one polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond.
  • the compound according to [1], wherein R 1 and R 4 in the formula (1) are each independently a terminal group represented by any one of the following formulas (3-1) to (3-4). Fluorine-containing ether compound.
  • Each of the (x+1) R 2 's in the formula (1) is independently any one selected from perfluoropolyether chains represented by the following formulas (4-1) to (4-4).
  • a second aspect of the present invention provides the following lubricant for magnetic recording media.
  • a lubricant for magnetic recording media comprising the fluorine-containing ether compound according to any one of [1] to [9].
  • a third aspect of the present invention provides the following magnetic recording medium.
  • a magnetic recording medium in which at least a magnetic layer, a protective layer, and a lubricant layer are sequentially provided on a substrate A magnetic recording medium characterized in that the lubricating layer contains the fluorine-containing ether compound according to any one of [1] to [9].
  • the magnetic recording medium according to the third aspect of the present invention preferably has the characteristics described in [12] below.
  • the magnetic recording medium according to [11], wherein the lubricating layer has an average thickness of 0.5 nm to 2.0 nm.
  • the fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is suitable as a material for a lubricant for magnetic recording media. Since the lubricant for magnetic recording media of the present invention contains the fluorine-containing ether compound of the present invention, it is possible to form a lubricant layer that has good flying stability and is highly effective in suppressing pickup.
  • the magnetic recording medium of the present invention has a lubricating layer containing the fluorine-containing ether compound of the present invention. Therefore, the magnetic recording medium of the present invention has good flying stability of the magnetic head, high pick-up suppressing effect, and excellent reliability and durability. Further, since the magnetic recording medium of the present invention has a lubricating layer that has good flying stability of the magnetic head and can suppress pickup, the flying height of the magnetic head can be further reduced.
  • FIG. 1 is a schematic cross-sectional view showing an embodiment of a magnetic recording medium of the present invention.
  • a lubricant having a chain structure containing multiple perfluoropolyether chains
  • a fluorine-containing ether compound in which an adsorption site having a polar group is arranged at the end of the chain structure and between the perfluoropolyether chains is preferably used.
  • the adsorption sites in the fluorine-containing ether compound combine with the active sites on the protective layer to improve the adhesion of the lubricating layer to the protective layer.
  • the fluorine-containing ether compound contained in the lubricating layer there are adsorption sites that do not interact with the active sites on the protective layer, and these adsorption sites are attracted to the magnetic head floating near the adsorption sites. Then, the fluorine-containing ether compound is taken up and attached to the magnetic head starting from the adsorption site adsorbed to the magnetic head, causing pickup.
  • the present inventors focused on the adsorption sites that can interact with the active points on the protective layer of the fluorine-containing ether compound contained in the lubricating layer.
  • adsorption sites (hereinafter sometimes referred to as “terminal adsorption sites”) are placed at both ends of a chain structure containing multiple perfluoropolyether chains, and adsorption sites are placed between adjacent perfluoropolyether chains.
  • An adsorption site (hereinafter sometimes referred to as “central adsorption site”) is placed on at least one of them, and the strength of the interaction between the terminal adsorption site and the active site on the protective layer and the central adsorption site and the protective layer are determined.
  • the interaction between the terminal adsorption sites and the active sites on the protective layer is too strong compared to the interaction between the central adsorption sites and the active sites on the protective layer, the interaction between the central adsorption sites and the active sites on the protective layer is too strong.
  • the lack of active sites results in a central adsorption site that is not involved in interaction with the active sites on the protective layer. As a result, the vicinity of the central adsorption site floats up and forms a lump, reducing the smoothness of the lubricating layer and reducing floating stability.
  • the end adsorption sites may interact with each other on the protective layer.
  • active sites on the protective layer resulting in terminal adsorption sites that are not involved in interaction with the active sites on the protective layer. In this case, the vicinity of the end attraction site floats up, and the vicinity of the end attraction site on the lubricant layer is attracted to the floating magnetic head, causing pickup.
  • the present inventors developed a structure of a terminal adsorption site and a central adsorption site that can interact with the active points on the protective layer with sufficient strength.
  • the terminal adsorption site is a terminal group having 2 to 4 polar groups, and the shortest distance between carbon atoms to which adjacent polar groups are bonded is 1 to 9 carbon atoms.
  • a terminal group having an oxygen atom bonded to a methylene group bonded to a fluoropolyether chain is arranged, and a divalent linkage represented by formula (2-1) or (2-2) is placed as a central adsorption site. It has been found that it is sufficient to use a fluorine-containing ether compound in which groups are arranged.
  • the divalent linking group represented by formula (2-1) or (2-2) is a highly flexible divalent linking group having two or three hydroxyl groups. More specifically, since the perfluoropolyether chain has a sterically bulky skeleton, the hydroxyl group of the divalent linking group placed between adjacent perfluoropolyether chains is located on both sides of the divalent linking group. Adsorption to the protective layer is likely to be inhibited by the perfluoropolyether chains arranged in each.
  • the adjacent perfluoropolyether chains has a central adsorption site of a divalent compound represented by formula (2-1) or (2-2).
  • a linking group is arranged.
  • the divalent linking group represented by formula (2-1) or (2-2) has 2 or 3 hydroxyl groups and has 6 or more atoms forming a chain structure. .
  • the number of carbon atoms arranged between the oxygen atoms forming the ether bond in the chain structure is 3. or four, and both ends are bonded to a perfluoropolyether chain via a methylene group by an ether bond. Therefore, it has appropriate flexibility.
  • the distance between adjacent perfluoropolyether chains is sufficiently ensured, and the adsorption of the hydroxyl group of the divalent linking group onto the protective layer is unlikely to be inhibited by the perfluoropolyether chain.
  • the divalent connecting group has Even if adsorption of one hydroxyl group to the protective layer is inhibited, one or two other hydroxyl groups can be adsorbed onto the protective layer.
  • the divalent linking group represented by formula (2-1) or (2-2) has sufficient flexibility, so that it can be Even if the fluoropolyether chain moves molecularly, it can move freely independently without interlocking with the perfluoropolyether chain. Therefore, the interaction between the divalent linking group represented by formula (2-1) or (2-2) and the active site on the protective layer is caused by Less affected by molecular movement of perfluoropolyether chains. Therefore, the divalent linking group represented by formula (2-1) or (2-2), which is the central adsorption site, is likely to participate in interaction with the active site on the protective layer.
  • it is a terminal group that has 2 to 4 polar groups at each end of a chain structure containing multiple perfluoropolyether chains, and between carbon atoms to which adjacent polar groups are bonded.
  • the shortest distance of carbon atoms is 1 to 9
  • a terminal group other than a terminal group having an oxygen atom bonded to a methylene group bonded to a perfluoropolyether chain is bonded.
  • the terminal groups may not be able to participate in the interaction with the active sites on the protective layer.
  • the terminal adsorption site has 2 to 4 polar groups, the distance between adjacent polar groups is appropriate, and an ether bond is formed with the methylene group bonded to the perfluoropolyether chain. It is a terminal group. Therefore, the two to four polar groups included in the terminal adsorption site are less susceptible to the effects of interactions between adjacent polar groups, and can exert sufficient adsorption power to the protective layer. From this, even if the divalent linking group represented by formula (2-1) or (2-2) is placed as the central adsorption site, the terminal adsorption sites interact with the active points on the protective layer. It can work.
  • a terminal adsorption site a terminal group having 2 to 4 polar groups, where the shortest distance between carbon atoms to which adjacent polar groups are bonded is 1 to 9 carbon atoms, and perfluorinated
  • a terminal group having an oxygen atom bonded to a methylene group bonded to a polyether chain is arranged, and a divalent linking group represented by formula (2-1) or (2-2) is placed as a central adsorption site.
  • Adsorption sites in the fluorine-containing ether compound that are not involved in interaction with active sites on the protective layer can be prevented from adsorbing to the magnetic head flying near the adsorption sites. Therefore, it is possible to form a lubricating layer that is less susceptible to pickup starting from the attraction site attracted to the magnetic head.
  • the central adsorption site and terminal adsorption sites of the fluorine-containing ether compound interact with the active sites on the protective layer, thereby providing good adsorption power to the protective layer. Therefore, even if an adsorption site that is not involved in interaction with the active points on the protective layer is adsorbed to the magnetic head, the fluorine-containing ether compound is taken up by the magnetic head starting from the adsorption site that is adsorbed to the magnetic head. It is difficult to use, and pickup can be suppressed.
  • the present inventors have confirmed that by using a lubricant containing the above-mentioned fluorine-containing ether compound, it is possible to form a lubricant layer with good floating stability and a high pick-up suppressing effect, and have conceived the present invention.
  • the fluorine-containing ether compound of this embodiment is represented by the following formula (1).
  • x represents an integer of 1 to 2;
  • R 2 is a perfluoropolyether chain;
  • (x+1) R 2 may be partly or completely the same; , may be different from each other;
  • R 3 is a divalent linking group having a hydroxyl group; at least one of the x R 3s is represented by the following formula (2-1) or (2-2).
  • R 1 and R 4 have two to two polar groups.
  • the fluorine-containing ether compound of this embodiment has a divalent linking group represented by R 3 and a perfluoropolyether chain (hereinafter referred to as "PFPE chain") represented by R 2 . ) have skeletons connected via methylene groups.
  • a terminal group represented by R 1 is bonded to one end of the skeleton via a methylene group, and a terminal group represented by R 4 is bonded to the other end of the skeleton via a methylene group.
  • x represents an integer of 1 to 2.
  • the number (x+1) of PFPE chains represented by R 2 is 2 or 3
  • the number of PFPE chains represented by R 2 is 2 or 3.
  • a divalent linking group having a hydroxyl group represented by R 3 is arranged between adjacent R 2 . Therefore, a lubricating layer with excellent adhesion to the protective layer can be obtained compared to a compound in which the number of PFPE chains represented by R 2 is one.
  • the molecule compared to a compound in which the number of PFPE chains represented by R 2 is four or more, the molecule does not become too large and can move freely. Therefore, it is easy to wet and spread on the protective layer, and it is easy to obtain a lubricating layer having a uniform thickness. Furthermore, since x is an integer of 1 to 2, the number of R 3 arranged between R 2 is 1 or 2. From this, the number of hydroxyl groups in -R 2 [-CH 2 -R 3 -CH 2 -R 2 ] x - in formula (1) is likely to be appropriate, and a lubricating layer with good adhesion to the protective layer is formed. Easy to obtain.
  • the fluorine-containing ether compound represented by formula (1) can prevent interactions between polar groups within the molecule, compared to, for example, when x is 3 or more, and the fluorine-containing ether compound The polar groups it has are unlikely to aggregate with each other. Therefore, it is possible to form a lubricating layer that has good flying stability and is highly effective in suppressing pickup.
  • x R 3 are each independently a divalent linking group having a hydroxyl group.
  • R 3 has a hydroxyl group, so when a lubricant containing this is used to form a lubricant layer on the protective layer, there is a gap between the lubricant layer and the protective layer. A favorable interaction occurs.
  • At least one of x R 3 's is a divalent linking group represented by formula (2-1) or (2-2). That is, when x is 1, R 3 is a linking group represented by formula (2-1) or (2-2). When x is 2, one or both of the two R 3s is a divalent linking group represented by formula (2-1) or (2-2).
  • the divalent linking groups represented by formulas (2-1) and (2-2) both have oxygen atoms at both ends of the chain structure, and the ether bond connects the divalent linking group represented by R 3 . Bonds to the methylene group bonded to the linking group.
  • the divalent linking group represented by formula (2-1) has four carbon atoms arranged between the oxygen atoms forming the ether bond in the chain structure, and has the formula (2-1).
  • the divalent linking group represented by 2) has three carbon atoms arranged between adjacent oxygen atoms forming an ether bond in the chain structure.
  • the oxygen atom contained in the chain structure of the divalent linking group represented by formulas (2-1) and (2-2) forms an ether bond to form a fluorine-containing ether compound represented by formula (1).
  • the divalent linking groups represented by formulas (2-1) and (2-2) have sufficient flexibility, so that the perfluoropolyether chains placed on both sides do not move molecularly. However, it can move freely independently without interlocking with the perfluoropolyether chain. Therefore, the divalent linking group represented by formula (2-1) or (2-2) is less susceptible to the molecular movement of the perfluoropolyether chains bonded to both sides of it through methylene groups, respectively. , are likely to be involved in interaction with active sites on the protective layer.
  • the divalent linking groups represented by formulas (2-1) and (2-2) both have 6 or more atoms forming a chain structure. Specifically, the divalent linking group represented by formula (2-1) has six atoms forming a chain structure. The number of atoms forming the chain structure of the divalent linking group represented by formula (2-2) is 9 when l in formula (2-2) is 1, and when l is 2 If so, there are 13 pieces. Therefore, in the above fluorine-containing ether compound, the divalent linking group represented by formula (2-1) or (2-2) ensures a sufficient distance between adjacent perfluoropolyether chains. Therefore, the adsorption of the hydroxyl group of the divalent linking group onto the protective layer is less likely to be inhibited by the perfluoropolyether chain.
  • the divalent linking group represented by formula (2-1) has two hydroxyl groups.
  • the divalent linking group represented by formula (2-2) has two or three hydroxyl groups. Since the divalent linking group represented by formula (2-1) or (2-2) has two or more hydroxyl groups, the lubricating layer containing the fluorine-containing ether compound has poor adhesion (adhesion) with the protective layer. properties) will be good. That is, even if one hydroxyl group in formula (2-1) or (2-2) is inhibited from being adsorbed to the protective layer due to the bulkiness of the perfluoropolyether chains on both sides, the other one or Two hydroxyl groups can be adsorbed onto the protective layer.
  • the number of hydroxyl groups in the divalent linking group is 3 or less, it interacts with the terminal groups represented by R 1 and R 4 in a magnetic recording medium having a lubricating layer containing a fluorine-containing ether compound. It is possible to suppress the generation of adsorption sites that are not involved in interaction with the active sites on the protective layer due to a shortage of active sites on the protective layer. Therefore, it is possible to prevent the occurrence of pickup caused by the vicinity of the adsorption site that is not involved in interaction with the active points on the protective layer floating and adhering to the magnetic head flying on the lubricant layer.
  • the number of hydroxyl groups in the above divalent linking group is preferably two, since the occurrence of pickup can be more effectively prevented.
  • the carbon atoms to which the two hydroxyl groups in formula (2-1) are bonded are directly bonded to each other. Therefore, the two hydroxyl groups in formula (2-1) are different from each other, for example, compared to the case where the carbon atoms to which the hydroxyl groups are bonded are bonded to each other via a rigid alkylene chain consisting of multiple methylene groups. You can exercise flexibly. Therefore, even if the perfluoropolyether chains arranged on both sides move molecularly, the two hydroxyl groups in the divalent linking group represented by formula (2-1) can move independently and freely. The interaction between the hydroxyl group in the divalent linking group and the protective layer is likely to be maintained.
  • the divalent linking group represented by formula (2-1) since the two hydroxyl groups are close to each other, the two hydroxyl groups The orientation in which the two are located in the same direction is restricted. In other words, the two hydroxyl groups contained in the divalent linking group represented by formula (2-1) are oriented in different directions with respect to the alkylene chain containing the carbon atom to which these hydroxyl groups are bonded. Cheap. Therefore, the dipoles induced by the two hydroxyl groups are approximately in opposite directions. From this, the total sum of dipole moments in the divalent linking group represented by formula (2-1) becomes small, and the surface free energy of the fluorine-containing ether compound becomes low. As a result, the lubricating layer containing the fluorine-containing ether compound is preferable because it is difficult to absorb chemical pollutants in the environment and has excellent resistance to chemical substances.
  • the divalent linking group represented by formula (2-2) includes a structure in which two to three glycerin structures (-O-CH 2 -CH(OH)-CH 2 -) are connected. Since the glycerin structure is flexible, the structure represented by formula (2-2) in which two to three glycerin molecules are linked is extremely flexible, and the hydroxyl group can move flexibly. Therefore, even when the perfluoropolyether chains placed on both sides undergo molecular movement, the two to three hydroxyl groups in the divalent linking group represented by formula (2-2) are independent of each other. The hydroxyl group in the divalent linking group can move freely, and the interaction between the hydroxyl group in the divalent linking group and the protective layer is easily maintained.
  • l represents an integer of 1 to 2.
  • the number of hydroxyl groups in the divalent linking group represented by formula (2-2) is two. Therefore, the interaction between the central portion (-R 2 [-CH 2 -R 3 -CH 2 -R 2 ] x -) of the fluorine-containing ether compound represented by formula (1) and the protective layer is too strong. This prevents the lack of active sites on the protective layer with which the terminal portions (R 1 --CH 2 -- and --CH 2 --R 4 ) can interact. Therefore, the fluorine-containing ether compound is capable of forming a lubricating layer in which the occurrence of pick-up due to lifting of the end portion of the fluorine-containing ether compound is further suppressed.
  • x is 2 and only one of the two R 3 is a divalent linkage represented by formula (2-1) or (2-2).
  • R 3 is a group
  • the one R 3 that is not the divalent linking group represented by formula (2-1) or (2-2) may be a divalent linking group having a hydroxyl group.
  • R 3 which is not the divalent linking group represented by formula (2-1) or (2-2), has oxygen atoms at both ends, and the ether bond connects the divalent linking group represented by R 3 . It is preferable that it be bonded to the methylene group bonded to the linking group.
  • the number of hydroxyl groups of R 3 that is not a divalent linking group represented by formula (2-1) or (2-2) can be, for example, 1 to 3, and 1 or 2. It is preferable that the number of As R 3 which is not a divalent linking group represented by formula (2-1) or (2-2), for example, a glycerin structure (-O-CH 2 -CH(OH)-CH 2 -O- ), etc.
  • R 1 and R 4 are terminal groups having 2 to 4 polar groups, and the shortest distance between carbon atoms to which adjacent polar groups are bonded is It is a terminal group having a distance of 1 to 9 carbon atoms and having an oxygen atom bonded to the methylene group (-CH 2 -) bonded to R 2 .
  • the lubricating layer containing the fluorine-containing ether compound represented by formula (1) has good floating stability and a high pick-up suppressing effect. Become something.
  • the lubricant layer A favorable interaction occurs between the protective layer and the protective layer.
  • the lubricating layer has excellent adhesion to the protective layer and is highly effective in suppressing pickup.
  • the number of polar groups contained in R 1 and R 4 is 4 or less, the polarity of the fluorine-containing ether compound is too high in the lubricating layer containing the fluorine-containing ether compound, and the fluorine-containing ether compound is It is possible to prevent the lubricating layer from agglomerating into lumps and losing the smoothness of the lubricating layer.
  • the number of polar groups contained in R 1 and R 4 is preferably 3 or less, and most preferably 2, since the fluorine-containing ether compound is less likely to aggregate.
  • R 1 and R 4 may be the same or different. Therefore, the number of polar groups that R 1 has and the number of polar groups that R 4 has may be the same or different.
  • the number of polar groups possessed by R 1 and the number of polar groups possessed by R 4 are such that the coating state of the fluorine-containing ether compound on the protective layer becomes more uniform, and a lubricating layer having better adhesion can be formed. Therefore, it is preferable that they be the same.
  • the total number of polar groups possessed by R 1 and polar groups possessed by R 4 in formula (1) is 4 to 8, preferably 4 to 6, more preferably 4 to 5, 4 is most preferred.
  • the interaction between the polar groups of R 1 and R 4 in the fluorine-containing ether compound and the protective layer becomes stronger.
  • the terminal group consisting of R 1 and R 4 which is an adsorption site for the fluorine-containing ether compound, separates from the protective layer, and the movement of the fluorine-containing ether compound from this portion as a starting point to the magnetic head is suppressed. Therefore, the fluorine-containing ether compound provides a lubricating layer with a high pick-up suppressing effect.
  • polar groups that are not involved in the bonding between the lubricating layer and the active sites on the protective layer are less likely to occur. Therefore, polar groups that are not involved in the bonding between the lubricating layer and the active sites on the protective layer can be prevented from agglomerating into protrusions and colliding with the magnetic head. Therefore, a lubricating layer with better flying stability can be formed, which is preferable.
  • each polar group of R 1 and R 4 is bonded to a different carbon atom, and each carbon atom to which a polar group is bonded has one carbon atom to which a polar group is not bonded. They are bonded via linking groups containing ⁇ 9. Therefore, the terminal polar group of R 1 and R 4 and the polar group adjacent to the terminal polar group are oriented so that they can adhere to the protective layer due to the linking group containing a carbon atom to which no polar group is bonded. be able to.
  • the terminal groups represented by R 1 and R 4 are less likely to float and form lumps, resulting in excellent floating stability.
  • atoms other than carbon atoms may exist between the carbon atoms to which adjacent polar groups are bonded. Examples of atoms other than carbon atoms include oxygen atoms and nitrogen atoms.
  • R 1 and R 4 are terminal groups having an oxygen atom bonded to the methylene group (-CH 2 -) bonded to R 2 . That is, R 1 and R 4 have oxygen atoms at the ends bonded to CH 2 adjacent to R 1 and R 4 , respectively.
  • the oxygen atoms placed at the ends of R 1 and R 4 form an ether bond (-O-) with the atoms bonded on both sides thereof.
  • This ether bond imparts appropriate flexibility to the fluorine-containing ether compound represented by formula (1) and increases the affinity between the polar groups of the terminal groups represented by R 1 and R 4 and the protective layer. .
  • the fluorine-containing ether compound represented by formula (1) can form a lubricating layer with excellent adhesion to the protective layer.
  • R 7 , R 8 , R 9 and R 10 are (each independently a hydrogen atom or an organic group) is preferably a polar group selected from the group consisting of: In the group having an amide bond, R 7 and R 8 may be bonded to each other to form a ring, and R 9 and R 10 may be bonded to each other to form a ring.
  • R 7 , R 8 , R 9 and R 10 in the group having an amide bond are each independently selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group.
  • the 2 to 4 polar groups each of R 1 and R 4 may have partially or entirely the same, or may be different.
  • R 1 and R 4 each independently contain at least one polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond. More preferably, R 1 and R 4 each contain at least one hydroxyl group as a polar group.
  • the two to four polar groups each of R 1 and R 4 have are preferably polar groups selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond.
  • R 1 and R 4 are preferably terminal groups each independently represented by any one of formulas (3-1) to (3-4). .
  • R 1 and R 4 are terminal groups represented by any of formulas (3-1) to (3-4), the polar group possessed by R 1 in formula (1) and the polarity possessed by R 4
  • the total number of groups (the number of hydroxyl groups and polar groups A when R 1 and/or R 4 are formula (3-1), and the total number of hydroxyl groups and polar groups A when R 1 and/or R 4 are formula (3-2), formula ( 3-3), and the total number of hydroxyl groups and polar groups B when R 1 and/or R 4 are formula (3-4) is 4 to 8, It is preferably 4 to 6, more preferably 4 to 5, and most preferably 4.
  • the terminal group represented by formula (3-1) is a carbon atom to which a polar group A placed at the end is bonded, and a carbon atom to which a hydroxyl group adjacent to the polar group A placed at the end is bonded.
  • the linking group between contains an oxygen atom forming an ether bond.
  • p represents an integer of 0 to 3
  • r represents an integer of 1 to 5
  • the total value of p and r is 1 to 5. Therefore, the above-mentioned linking group has a linear structure consisting of 3 to 7 atoms including the polar group A and a carbon atom to which no hydroxyl group is bonded.
  • the connecting group contains an oxygen atom forming an ether bond, and is composed of three or more atoms containing a polar group A and a carbon atom to which a hydroxyl group is not bonded. Since it has a linear structure, the distance between the polar group A and the hydroxyl group adjacent to the polar group A is appropriate. Therefore, interaction between the polar group A and the hydroxyl group adjacent to the polar group A within the molecule can be suppressed, and both the polar group A and the hydroxyl group adjacent to the polar group A can adhere to the protective layer. Moreover, since the above-mentioned linking group has a linear structure consisting of three or more atoms, molecular mobility is appropriate and intramolecular aggregation is less likely to occur.
  • the connecting group contains an oxygen atom forming an ether bond and has a linear structure consisting of 7 or less atoms including a carbon atom to which a polar group A and a hydroxyl group are not bonded
  • the connecting group The hydrophobicity is so high that it does not interfere with the adhesion with the protective layer.
  • a lubricating layer containing a fluorine-containing ether compound in which the connecting group has a linear structure of 3 to 7 atoms including a polar group A and a carbon atom to which no hydroxyl group is bonded can be used as a protective layer. It has excellent adhesion, provides excellent floating stability, and has a high pick-up suppressing effect.
  • the total value of p and r is 1 to 5, preferably 1 to 3.
  • the carbon atoms contained in the linking group arranged between the carbon atoms to which the polar groups are bonded are such that the intramolecular interaction between adjacent polar groups causes mutual interaction between the polar groups and the protective layer. This prevents the occurrence of the effect preferentially and improves the adhesion between the polar groups in R 1 and R 4 and the protective layer.
  • the number of carbon atoms contained in the linking group is too large, the flexibility of the terminal groups represented by R 1 and R 4 will decrease, making it difficult to uniformly coat the protective layer. be.
  • the total value of p and r is 5 or less, so the alkylene chains of the main chain portions of R 1 and R 4 are not too long. Therefore, since the rigid alkylene chain is long, the flexibility of the terminal portion is reduced, the interaction with the protective layer is weakened, and lifting of the terminal portion can be prevented.
  • p is preferably 0 or 1, more preferably 0.
  • r is preferably 1 or 2, more preferably 1.
  • a in formula (3-1) represents a polar group.
  • A is more preferably a polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond, and even more preferably a hydroxyl group, an acetamido group, or a carboxamide group.
  • a in formula (3-1) is a hydroxyl group
  • all polar groups in formula (3-1) are hydroxyl groups.
  • the polar groups of R 1 and R 4 are all hydroxyl groups, the state of coating of the fluorine-containing ether compound on the protective layer becomes more uniform, and a lubricating layer with better adhesion can be formed.
  • R 1 and R 4 when one of R 1 and R 4 has the formula (3-1) and A is a hydroxyl group, the other of R 1 and R 4 has the formula (3-1) where A is a hydroxyl group. ), formula (3-2), or formula (3-3).
  • a in formula (3-1) is an acetamido group or a carboxamide group, the fluorine-containing ether compound can form a lubricating layer with stronger interaction with the protective layer.
  • q represents an integer from 0 to 2.
  • the number of polar groups in formula (3-1) is q+2, and as mentioned above, the number of polar groups contained in R 1 and R 4 is preferably 3 or less, and 2 each. Most preferably. Therefore, q in formula (3-1) is preferably 0 or 1, more preferably 0.
  • the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded does not contain an oxygen atom.
  • t in formula (3-2) represents an integer from 1 to 5. Therefore, the above-mentioned linking group has a linear structure consisting of 1 to 5 atoms including carbon atoms to which no hydroxyl group is bonded.
  • the above-mentioned linking group included in formula (3-2) has a linear structure consisting of one or more atoms including a carbon atom to which no hydroxyl group is bonded, so it has a terminal hydroxyl group and a hydroxyl group adjacent to the terminal hydroxyl group The distance between the two is appropriate. Therefore, interaction between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group within the molecule can be suppressed, and intramolecular aggregation is less likely to occur.
  • t is 5 or less, so the alkylene chains of the main chain portions of R 1 and R 4 are not too long. Therefore, since the rigid alkylene chain is long, the flexibility of the terminal portion is reduced, the interaction with the protective layer is weakened, and lifting of the terminal portion can be prevented.
  • t is preferably 4 or less, more preferably 1 or 2, and even more preferably 1.
  • the above-mentioned linking group does not contain an oxygen atom forming an ether bond and has a linear structure consisting of 5 or less atoms including a carbon atom to which a hydroxyl group is not bonded
  • the hydrophobicity of the linking group is so high that it does not impede the adhesion with the protective layer.
  • the lubricating layer containing the above has excellent adhesion with the protective layer, provides excellent flying stability, and has a high pick-up suppressing effect.
  • s represents an integer from 0 to 2.
  • the number of polar groups in formula (3-2) is s+2, and as mentioned above, the number of polar groups contained in R 1 and R 4 is preferably 3 or less, and 2 each. Most preferably. Therefore, s in formula (3-2) is preferably 0 or 1, and more preferably 0.
  • the terminal group represented by formula (3-3) does not have a secondary hydroxyl group and has two primary hydroxyl groups.
  • the hydroxyl group contained in R 1 and/or R 4 is a primary hydroxyl group
  • the hydroxyl group is more likely to interact with the active site on the protective layer than when it is a secondary hydroxyl group.
  • the terminal group represented by formula (3-3) does not have a secondary hydroxyl group and only has two primary hydroxyl groups that easily interact with the active sites on the protective layer. Therefore, when R 1 and/or R 4 are terminal groups represented by formula (3-3), the fluorine-containing ether compound can form a lubricating layer with good adhesion to the protective layer.
  • the linking group between the carbon atoms to which two primary hydroxyl groups are bonded connects to the carbon atom to which no hydroxyl group is bonded, and to the ether bond.
  • u in formula (3-3) represents an integer of 2 to 4.
  • Y represents a linear alkylene group which may have an ether oxygen or a single bond.
  • the above-mentioned linking group has a structure consisting of 3 to 10 atoms, including a carbon atom to which no hydroxyl group is bonded, and an oxygen atom forming an ether bond.
  • the connecting group contains an oxygen atom forming an ether bond, and has a structure consisting of three or more atoms including a carbon atom to which a hydroxyl group is not bonded. Therefore, the distance between the two primary hydroxyl groups is appropriate. Therefore, molecular mobility is appropriate and intramolecular aggregation is less likely to occur. Therefore, the fluorine-containing ether compound can form a lubricating layer with good adhesion to the protective layer.
  • the connecting group contains an oxygen atom forming an ether bond, and a structure consisting of 10 or less atoms including a carbon atom to which a hydroxyl group is not bonded. Therefore, the hydrophobicity of the linking group is so high that it does not interfere with the adhesion with the protective layer. Therefore, a lubricating layer containing a fluorine-containing ether compound in which the connecting group includes an oxygen atom forming an ether bond and has a structure consisting of 3 to 10 atoms including a carbon atom to which no hydroxyl group is bonded is a protective layer. It has excellent adhesion to the surface, provides excellent flying stability, and has a high pick-up suppressing effect.
  • u in formula (3-3) is 2 or more, -O-(CH 2 ) u -OH in formula (3-3) (hereinafter sometimes referred to as "side chain moiety").
  • the PFPE chain represented by R 2 which is bonded to R 1 and R 4 via a methylene group, and the tertiary carbon to which the side chain portion of formula (3-3) is bonded.
  • the distance from bulky parts such as Therefore, the primary hydroxyl group contained in the side chain portion of formula (3-3) can easily move freely.
  • u is 4 or less, the flexibility of the side chain portion in formula (3-3) is maintained. Therefore, the fluorine-containing ether compound has excellent adhesion with the protective layer, exhibits high flying stability, and can form a lubricating layer with a high pick-up suppressing effect.
  • u is preferably 2 or 3, more preferably 2.
  • the primary hydroxyl group contained in -Y-CH 2 -OH is bonded to the side chain portion of formula (3-3) via -Y-CH 2 -. Bonded to a carbon atom. Therefore, the primary hydroxyl group contained in -Y-CH 2 -OH is more likely to move freely than when the hydroxyl group is directly bonded to the carbon atom, and interacts with the active site on the protective layer. easy to get involved in.
  • Y is not a single bond but a linear alkylene group which may have an ether oxygen.
  • the primary hydroxyl group contained in -Y-CH 2 -OH, the PFPE chain represented by R 2 bonded to R 1 and R 4 via a methylene group, and the side chain of formula (3-3) This is because the distance from the bulky site such as tertiary carbon to which the moiety is bonded increases, and the primary hydroxyl group contained in -Y-CH 2 -OH becomes more likely to move freely.
  • the total number of carbon atoms and oxygen atoms that Y has is 1 to 5.
  • the total number of carbon atoms and oxygen atoms in Y is 5 or less, so the alkylene chain in the main chain part in formula (3-3) is not too long. Become something. Therefore, since the rigid alkylene chain is long, the flexibility of the terminal portion is reduced, the interaction with the protective layer is weakened, and lifting of the terminal portion can be prevented.
  • the total number of carbon atoms and oxygen atoms in Y is preferably 1 to 4, more preferably 1 to 3.
  • the number of carbon atoms in Y is preferably 1 to 3, more preferably 1 to 2.
  • Y in formula (3-3) is a linear alkylene group which may have an ether oxygen
  • Y is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 --, --CH 2 OCH 2 --, --CH 2 OCH 2 CH 2 --, --CH 2 OCH 2 CH 2 CH 2 --, --CH 2 CH 2 OCH 2 --, and the like.
  • the linking group between the carbon atom to which polar group B is bonded and the carbon atom to which the hydroxyl group adjacent to polar group B is bonded is an ether bond.
  • the above linking group has a structure consisting of 3 to 5 atoms including the polar group B and a carbon atom to which no hydroxyl group is bonded.
  • the number of atoms in the connecting group refers to the number of atoms at the shortest distance between the carbon atom to which the polar group B is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group B is bonded.
  • the connecting group contains an oxygen atom forming an ether bond, and is composed of three or more atoms including a carbon atom to which a polar group B and a hydroxyl group are not bonded. Therefore, the distance between the polar group B and the hydroxyl group adjacent to the polar group B is appropriate. Furthermore, since the benzene ring is rigid, it is difficult to rotate it freely. Therefore, interaction between the polar group B substituted on the benzene ring and the hydroxyl group adjacent to the polar group B can be suppressed.
  • the carbon atoms to which adjacent hydroxyl groups are bonded are contained in -(CH 2 CH (OH) CH 2 O) v -.
  • the connecting group between them includes an oxygen atom forming an ether bond, and has a linear structure consisting of three atoms including a polar group B and a carbon atom to which a hydroxyl group is not bonded. Since the above-mentioned connecting group has a linear structure consisting of three atoms including the polar group B and a carbon atom to which no hydroxyl group is bonded, the distance between adjacent hydroxyl groups is appropriate. Therefore, interaction between hydroxyl groups within the molecule can be suppressed.
  • a lubricating layer containing a fluorine-containing ether compound having a terminal group represented by formula (3-4) has excellent adhesion with the protective layer, provides excellent flying stability, and has a high pick-up suppressing effect. Become something.
  • B in formula (3-4) represents a polar group substituted at any position on the benzene ring.
  • B is more preferably a polar group selected from the group consisting of a cyano group and a group having an amide bond, and even more preferably a cyano group, an acetamido group, or a carboxamide group.
  • v represents an integer from 1 to 3.
  • the number of polar groups in formula (3-4) is v+1, and as described above, the number of polar groups contained in R 1 and R 4 is preferably 3 or less, and 2 each. Most preferably. Therefore, v in formula (3-4) is preferably 1 or 2, more preferably 1.
  • R 1 and R 4 may be the same or different.
  • the coating state of the fluorine-containing ether compound on the protective layer becomes more uniform, and a lubricating layer with better adhesion can be formed.
  • R 2 is a perfluoropolyether chain.
  • PFPE chain represented by R2 is a perfluoropolyether chain.
  • R 2 cover the surface of the protective layer and provide lubrication to the lubricant layer. This reduces the frictional force between the magnetic head and the protective layer.
  • the PFPE chain represented by R 2 is appropriately selected depending on the performance required of a lubricant containing a fluorine-containing ether compound.
  • Part or all of the (x+1) R 2 's may be the same, or may be different. It is preferable that all (x+1) R 2 are the same. This is because the coating state of the fluorine-containing ether compound on the protective layer becomes more uniform, resulting in a lubricating layer with better adhesion.
  • Two or more R2s out of (x+1) R2s are the same means that out of (x+1) R2s , two or more R2s with the same repeating unit structure of the PFPE chain are included. It means there is.
  • the same R 2 also includes those having the same repeating unit structure but different average degrees of polymerization.
  • Examples of the PFPE chain represented by R 2 include those made of a perfluoroalkylene oxide polymer or copolymer.
  • Examples of the perfluoroalkylene oxide include perfluoromethylene oxide, perfluoroethylene oxide, perfluoro-n-propylene oxide, perfluoroisopropylene oxide, and perfluorobutylene oxide.
  • (x+1) R 2 in formula (1) are each independently a PFPE chain represented by the following formula (4) derived from a polymer or copolymer of perfluoroalkylene oxide, for example. . -(CF 2 ) w1 -O-(CF 2 O) w2 -(CF 2 CF 2 O) w3 - (CF 2 CF 2 CF 2 O) w4 - (CF 2 CF 2 CF 2 CF 2 O) w5 -( CF 2 ) w6 - (4)
  • w2, w3, w4, and w5 indicate the average degree of polymerization, and each independently represents 0 to 20; however, all of w2, w3, w4, and w5 are They never become 0 at the same time; w1 and w6 are average values representing the number of CF 2 and each independently represents 1 to 3; (CF 2 O), (CF There is no particular restriction on the arrangement order of (CF 2 CF 2
  • w2, w3, w4, and w5 represent average degrees of polymerization, each independently representing 0 to 20, preferably 0 to 15, and more preferably 0 to 10. It may be 1-8, 2-6, 3-5, etc.
  • w1 and w6 are average values indicating the number of CF 2 and each independently represents 1 to 3.
  • w1 and w6 are determined depending on the structure of repeating units arranged at the ends of the chain structure in the PFPE chain represented by formula (4).
  • (CF 2 O), (CF 2 CF 2 O), (CF 2 CF 2 CF 2 O), and (CF 2 CF 2 CF 2 O) in formula (4) are repeating units. There is no particular restriction on the arrangement order of the repeating units in formula (4). Further, there is no particular restriction on the number of types of repeating units in formula (4).
  • (x+1) R 2 in formula (1) are each independently selected from PFPE chains represented by the following formulas (4-1) to (4-4).
  • (x+1) R 2 are each one selected from the PFPE chains represented by formulas (4-1) to (4-4)
  • a lubricating layer with good lubricity can be obtained. It becomes a fluorine-containing ether compound.
  • oxygen relative to the number of carbon atoms in the PFPE chain The ratio of the number of atoms (the number of ether bonds (-O-)) is appropriate. Therefore, the fluorine-containing ether compound has appropriate hardness.
  • the fluorine-containing ether compound applied on the protective layer is unlikely to aggregate on the protective layer, and a thinner lubricating layer can be formed with a sufficient coverage. Furthermore, since the fluorine-containing ether compound has appropriate flexibility, a lubricating layer with better flying stability can be formed.
  • formula (4-1) there is no particular restriction on the arrangement order of the repeating units (OCF 2 CF 2 ) and (OCF 2 ).
  • the number h of (OCF 2 CF 2 ) and the number i of (OCF 2 ) may be the same or different.
  • the PFPE chain represented by formula (4-1) may be a polymer of (OCF 2 CF 2 ).
  • the PFPE chain represented by formula (4-1) is a random copolymer, a block copolymer, or an alternating copolymer consisting of (OCF 2 CF 2 ) and (OCF 2 ). Good too.
  • h indicating the average degree of polymerization is 1 to 20, i is 0 to 20, j is 1 to 15, and k is 1 to 10, so good lubrication is achieved.
  • the resulting fluorine-containing ether compound provides a lubricating layer with properties.
  • h and i, which indicate the average degree of polymerization are 20 or less, j is 15 or less, and k is 10 or less, so the viscosity of the fluorine-containing ether compound is high. It is preferable because it does not become too thick and the lubricant containing it is easy to apply.
  • h, i, j, and k which indicate the average degree of polymerization, are preferably from 1 to 10 because the fluorine-containing ether compound easily spreads on the protective layer and provides a lubricating layer with a uniform thickness. , more preferably from 1.5 to 8, and even more preferably from 2 to 7.
  • formula (4-4) there is no particular restriction on the arrangement order of the repeating units (CF 2 CF 2 CF 2 O) and (CF 2 CF 2 O).
  • the number w8 of (CF 2 CF 2 CF 2 O) and the number w9 of (CF 2 CF 2 O) indicating the average degree of polymerization may be the same or different.
  • Formula (4-4) includes a random copolymer, a block copolymer, or an alternating copolymer consisting of monomer units (CF 2 CF 2 CF 2 O) and (CF 2 CF 2 O). It may be.
  • w8 and w9 indicating the average degree of polymerization are each independently from 1 to 20, preferably from 1 to 15, and more preferably from 1 to 10.
  • w7 and w10 in formula (4-4) are average values indicating the number of CF 2 and each independently represents 1 to 2.
  • w7 and w10 are determined depending on the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (4-4).
  • the fluorine-containing ether compound represented by formula (1) is preferably one of the compounds represented by the following formulas (AA) to (AV) and (BA) to (BK).
  • the compound represented by formula (1) is one of the compounds represented by the following formulas (AA) to (AV) and (BA) to (BK)
  • the raw materials are easily available and the thickness is thin.
  • Rf 1 , Rf 2 , and Rf 3 representing PFPE chains have the following structures, respectively. That is, in the compounds represented by the following formulas (AA) to (AP), (AS) to (AV), (BA) to (BI), and (BK), Rf 1 is represented by the above formula (4-1). The PFPE chains represented. In the compounds represented by the following formulas (AQ) and (BJ), Rf 2 is a PFPE chain represented by the above formula (4-2). In the compound represented by the following formula (AR), Rf 3 is a PFPE chain represented by the above formula (4-3).
  • h and i in Rf 1 representing the PFPE chains in formulas (AA) to (AV) and (BA) to (BK), j in Rf 2 , and k in Rf 3 are values indicating the average degree of polymerization. Therefore, it is not necessarily an integer.
  • R 3 is a linkage represented by the above formula (2-1) or (2-2). It is the basis.
  • R 1 and R 4 are each one of the above formulas (3-1) to (3-4). This is the terminal group represented by In the compounds represented by the following formulas (AA) to (AV) and (BA) to (BK), (x+1) R 2 's in formula (1) are the same.
  • x in formula (1) is 1.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1) or (3-2).
  • R 3 is a linking group represented by the above formula (2-1).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • x in formula (1) is 1.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1).
  • R 3 is a linking group represented by the above formula (2-2).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • R 1 and R 4 are terminal groups represented by the above formula (3-1).
  • R 3 is a linking group represented by the above formula (2-1).
  • R 2 is a PFPE chain represented by the above formula (4-2).
  • R 2 is a PFPE chain represented by the above formula (4-3).
  • x in formula (1) is 1.
  • R 1 and R 4 are terminal groups represented by the above formula (3-3).
  • R 3 is a linking group represented by the above formula (2-1).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • x in formula (1) is 1.
  • R 1 and R 4 are terminal groups represented by the above formula (3-4).
  • R 3 is a linking group represented by the above formula (2-1).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • x in formula (1) is 2.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1) or (3-2).
  • R 3 is a linking group represented by the above formula (2-1).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • x in formula (1) is 2.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1).
  • R 3 is a linking group represented by the above formula (2-2).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • x in formula (1) is 2.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1).
  • One of the two R 3s is a linking group represented by the above formula (2-1), and the other is a glycerin structure (-O-CH 2 -CH(OH)-CH 2 -O-).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • x in formula (1) is 2.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1).
  • R 3 is a linking group represented by the above formula (2-1).
  • R 2 is a PFPE chain represented by the above formula (4-2).
  • x in formula (1) is 2.
  • R 1 and R 4 are terminal groups represented by the above formula (3-1).
  • R 3 is a linking group represented by the above formula (2-2).
  • R 2 is a PFPE chain represented by the above formula (4-1).
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • j represents the average degree of polymerization and represents 1 to 15; In the two Rf 2 , the average degree of polymerization may be the same or different.
  • k indicates the average degree of polymerization and represents 1 to 10; in the two Rf 3s , the average degree of polymerization may be the same or different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; In the two Rf 1s , the average degree of polymerization is the same. may be different, or may be different.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1 , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1s , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1s , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1 , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1s , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1s , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1s , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1 , respectively They may be different, or may be partially or entirely the same.
  • h and i indicate the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf 1s , respectively They may be different, or may be partially or entirely the same.
  • j indicates the average degree of polymerization and represents 1 to 15; There may be.)
  • the number average molecular weight (Mn) of the fluorine-containing ether compound of the present embodiment is preferably within the range of 500 to 10,000, particularly preferably within the range of 1,000 to 5,000. It may be 2000-4500, 2500-4000, 3000-3500, etc. When the number average molecular weight is 500 or more, the lubricating layer made of the lubricant containing the fluorine-containing ether compound of this embodiment has excellent heat resistance.
  • the number average molecular weight of the fluorine-containing ether compound is more preferably 1000 or more.
  • the number average molecular weight of the fluorine-containing ether compound becomes appropriate, and by applying a lubricant containing this, a thin lubricating layer can be easily formed.
  • the number average molecular weight of the fluorine-containing ether compound is preferably 5,000 or less since it has a viscosity that is easy to handle when applied to a lubricant.
  • the number average molecular weight (Mn) of the fluorine-containing ether compound is a value measured by 1 H-NMR and 19 F-NMR using AVANCE III400 manufactured by Bruker Biospin. Specifically, the number of repeating units of the PFPE chain is calculated from the integral value measured by 19 F-NMR, and the number average molecular weight is determined.
  • NMR nuclear magnetic resonance
  • the sample is diluted into a hexafluorobenzene/d-acetone (4/1 v/v) solvent.
  • the standard for 19 F-NMR chemical shift is the peak of hexafluorobenzene at -164.7 ppm
  • the standard for 1 H-NMR chemical shift is the peak of acetone at 2.2 ppm.
  • the fluorine-containing ether compound of this embodiment is preferably subjected to molecular weight fractionation by an appropriate method to have a molecular weight dispersity (weight average molecular weight (Mw)/number average molecular weight (Mn) ratio) of 1.3 or less.
  • the method of molecular weight fractionation is not particularly limited, but for example, molecular weight fractionation using silica gel column chromatography, gel permeation chromatography (GPC), etc., molecular weight fractionation using supercritical extraction, etc. can be used.
  • the method for producing the fluorine-containing ether compound of this embodiment is not particularly limited, and can be produced using a conventionally known production method.
  • the fluorine-containing ether compound of this embodiment can be manufactured using, for example, the manufacturing method shown below.
  • THP in the following formulas (5-1) to (5-10) represents a tetrahydropyranyl group.
  • the number of methylene groups (a1 in formula (6-1)) contained in the halogen compound having an epoxy group is 1 to 4, and can be appropriately determined depending on the structure of the terminal group of the compound to be synthesized.
  • R represents a structure corresponding to a part of the terminal group represented by R 1 (or R 4 ) in formula (1); a1 represents an integer of 1 to 4.
  • the above-mentioned epoxy compound may be manufactured using the method shown below. That is, as shown in the following formula (6-2), a structure (R in formula (6-2)) corresponding to a part of the terminal group represented by R 1 (or R 4 ) in formula (1) and a halogen compound such as a bromine compound or a chlorine compound having an alkenyl group (formula (6-2) is a case where the halogen compound is a bromine compound). Thereafter, the obtained compound can be produced using a method in which it is oxidized by the action of m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • the number of methylene groups (a2 in formula (6-2)) contained in the halogen compound having an alkenyl group is 1 to 4, and can be appropriately determined depending on the structure of the terminal group of the compound to be synthesized.
  • R represents a structure corresponding to a part of the terminal group represented by R 1 (or R 4 ) in formula (1); a2 represents an integer of 1 to 4.
  • the above-mentioned epoxy compound may be manufactured using the method shown below. That is, as shown in the following formula (6-3), a structure (R in formula (6-3)) corresponding to a part of the terminal group represented by R 1 (or R 4 ) in formula (1) An addition reaction is carried out between an alcohol having an alkenyl group and a compound having an alkenyl group and an epoxy group. Thereafter, the compound obtained by the addition reaction can be produced using a method in which m-chloroperbenzoic acid (mCPBA) is applied to oxidize the compound.
  • mCPBA m-chloroperbenzoic acid
  • the hydroxyl group generated by the addition reaction may be protected by a known method.
  • the number of methylene groups (a3 in formula (6-3)) contained in the compound having an alkenyl group and an epoxy group is 1 to 4, and can be appropriately determined depending on the structure of the terminal group of the compound to be synthesized.
  • R represents a structure corresponding to a part of the terminal group represented by R 1 (or R 4 ) in formula (1); a3 represents an integer of 1 to 4.
  • the hydroxyl group at one end of the intermediate compound 1-1 produced in the first reaction described above is reacted with a compound having two epoxy groups corresponding to R 3 in formula (1) (second reaction).
  • a compound having two epoxy groups corresponding to R 3 in formula (1) for example, compounds represented by the following formulas (7-1) to (7-3) can be used.
  • THP in the following formula (7-3) represents a tetrahydropyranyl group.
  • a compound represented by formula (7-3) As the epoxy compound, it can be produced, for example, using the method shown below. That is, as shown in the following formula (8-2), a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (formula (8-2) is a case where the halogen compound is a bromine compound) and an alkenyl group. React with alcohol (allyl alcohol). Then, it can be produced using a method in which the secondary hydroxyl group of the compound produced after the reaction is protected using dihydropyran, and the alkenyl group is oxidized by the action of m-chloroperbenzoic acid (mCPBA). THP in formula (8-2) represents a tetrahydropyranyl group.
  • mCPBA m-chloroperbenzoic acid
  • the compound represented by formula (7-3) may be produced, for example, using the method shown below. That is, as shown in the following formula (8-3), a compound having two hydroxyl groups and a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (in formula (8-3), the halogen compound is a bromine compound) can be produced using a method of reacting with THP in formula (8-3) represents a tetrahydropyranyl group.
  • a commercially available product may be used as the compound having two epoxy groups corresponding to R 3 in formula (1).
  • x in formula (1) is 1, and R 1 and R 4 are of formulas (3-1), (3-2). ) or (3-4), in which R 1 and R 4 are the same, and two R 2 are the same, can be produced.
  • Intermediate Compound 1-2 is reacted with a compound having a leaving group and a protected hydroxyl group corresponding to R 3 in Formula (1), to form Intermediate Compound 1-3.
  • second reaction examples of the compound having a leaving group and a protected hydroxyl group corresponding to R 3 include a compound represented by the formula (14) described below, a compound represented by the following formula (31), and a compound represented by the following formula (32).
  • Examples include compounds represented by: THP in formulas (31) and (32) represents a tetrahydropyranyl group, and Ts represents a tosyl group (p-toluenesulfonyl group).
  • the terminal group represented by formula (3-3) is A halogen compound having a protected hydroxyl group corresponding to -(CH 2 ) u -OH in the side chain portion is reacted (third reaction).
  • the halogen compound having a protected hydroxyl group corresponding to -(CH 2 ) u -OH in the side chain portion of the terminal group represented by formula (3-3) include those represented by formula (16) described below. Examples include a compound represented by the following formula (33), a compound represented by the following formula (34), and the like.
  • THP in formulas (33) and (34) represents a tetrahydropyranyl group.
  • intermediate compound 1a is reacted with a compound having an epoxy group and an alkenyl group corresponding to R 3 in formula (1), and then the double bond of the purified compound is removed. Oxidation yields intermediate compound 1-4 (third reaction).
  • the compound having an epoxy group and an alkenyl group corresponding to R 3 in formula (1) for example, compounds represented by formulas (9-1) to (9-3) described below can be used.
  • x in formula (1) is 1, and R 1 and R 4 are of formulas (3-1), (3-2). ) or (3-4) in which R 1 and R 4 are different and/or two R 2 are different.
  • intermediate compound 1-2a is reacted with the leaving group at one end of the compound having a leaving group and a protected hydroxyl group corresponding to R 3 in formula (1). , to obtain intermediate compound 1-3a (third reaction).
  • intermediate compound 1-2b is reacted with the leaving group of intermediate compound 1-3a obtained in the third reaction to obtain intermediate compound 1-3b (fourth reaction ).
  • R 1 is represented by formula (3-3).
  • a halogen compound having a protected hydroxyl group corresponding to -(CH 2 ) u -OH in the side chain portion of the terminal group is reacted to obtain intermediate compound 1-5 (fifth reaction).
  • R 4 is represented by formula (3-3).
  • a deprotection reaction is performed using a known method to obtain a terminal in which x in formula (1) is 1 and R 1 and R 4 are represented by formula (3-3). group, and compounds in which R 1 and R 4 are different can be produced.
  • R 1 is represented by formula (3-3).
  • x in formula (1) is 1 and R 1 is a terminal group represented by formula (3-3).
  • R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4) can be produced.
  • a fluorine-based compound is prepared in which hydroxymethyl groups (-CH 2 OH) are placed at both ends of the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1).
  • the hydroxyl groups of the hydroxymethyl groups located at both ends of the fluorine-based compound are reacted with a compound having an epoxy group and an alkenyl group corresponding to R 3 in formula (1) (second reaction).
  • THP in the following formula (9-3) represents a tetrahydropyranyl group.
  • a compound represented by formula (9-3) As the epoxy compound, it can be produced, for example, by the method shown below. That is, as shown in the following formula (10-1), a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (formula (10-1) is a case where the halogen compound is a bromine compound) and an alkenyl group. React with alcohol (allyl alcohol). Then, the secondary hydroxyl group of the compound generated after the reaction is protected using dihydropyran, and then m-chloroperbenzoic acid (mCPBA) is applied to oxidize only one alkenyl group. . THP in the following formula (10-1) represents a tetrahydropyranyl group.
  • mCPBA m-chloroperbenzoic acid
  • the compound represented by formula (9-3) may be produced, for example, using the method shown below. That is, as shown in the following formula (10-2), a compound having two hydroxyl groups and a halogen compound such as a bromine compound or a chlorine compound having an alkenyl group (in formula (10-2), the halogen compound is a bromine compound) After introducing a substituent having an alkenyl group to one of the hydroxyl groups, a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (Formula (10-2) is a halogen compound is a bromine compound. It can be produced using a method of reacting (in case). THP in the following formula (10-2) represents a tetrahydropyranyl group.
  • m-chloroperbenzoic acid mCPBA
  • third reaction m-chloroperbenzoic acid
  • intermediate compound 2-1 has epoxy groups corresponding to two R 3 in formula (1) at both ends of the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1). can get.
  • the third reaction may be carried out after the hydroxyl group of the compound produced after the second reaction is appropriately protected by a known method.
  • a fluorine-based compound is prepared in which hydroxymethyl groups (-CH 2 OH) are placed at both ends of the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1).
  • the hydroxyl groups of the hydroxymethyl groups located at both ends of the fluorine-based compound are reacted with a compound having a leaving group and a protected hydroxyl group corresponding to R 3 in formula (1) (second reaction). ).
  • second reaction results in an intermediate compound 2- having a structure corresponding to two R 3 in formula (1) and a leaving group at both ends of the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1). 2 is obtained.
  • the terminal group represented by formula (3-3) is A halogen compound having a protected hydroxyl group corresponding to -(CH 2 ) u -OH in the side chain portion is reacted (fourth reaction).
  • the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1) has epoxy groups corresponding to two R 3 in formula (1) at both ends of the perfluoropolyether chain.
  • Intermediate compound 2-1 is produced (third reaction).
  • x in formula (1) is 2, two R 3 are the same, and R 1 and R 4 are of the formula ( 3-1), (3-2) or (3-4), and when R 1 and R 4 are different, and/or R 2 on the R 1 side and R on the R 4 side Compounds in which 2 are different can be produced.
  • intermediate compound 2- 6 is obtained (fifth reaction).
  • R 1 is represented by formula (3-3).
  • a halogen compound having a protected hydroxyl group corresponding to -(CH 2 ) u -OH in the side chain portion of the terminal group is reacted to obtain intermediate compound 2-7 (sixth reaction).
  • R 4 is represented by formula (3-3). ( 7th reaction ).
  • an intermediate compound 1b having a group corresponding to R 4 at one end of the perfluoropolyether chain corresponding to R 2 on the R 4 side is produced (second reaction ). Thereafter, the hydroxyl group of the hydroxymethyl group located at one end of intermediate compound 1b is reacted with the leaving group of intermediate compound 2-5 to obtain intermediate compound 2-8 (third reaction).
  • R 1 is represented by formula (3-3).
  • x in formula (1) is 2 and R 1 is a terminal group represented by formula (3-3).
  • R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4) can be produced.
  • a fluorine-based compound is prepared in which hydroxymethyl groups (-CH 2 OH) are arranged at both ends of a perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1).
  • the hydroxyl group of the hydroxymethyl group located at one end of the fluorine-based compound is reacted with a compound having an epoxy group and an alkenyl group corresponding to one R 3 in formula (1).
  • the generated compound is reacted with a compound having an epoxy group and an alkenyl group corresponding to the other R 3 in formula (1).
  • the generated compound is treated with m-chloroperbenzoic acid (mCPBA) to oxidize the alkenyl group.
  • mCPBA m-chloroperbenzoic acid
  • one end of the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1) has an epoxy group corresponding to one R 3 in formula (1), and the other end has an epoxy group corresponding to one R 3 in formula (1).
  • an intermediate compound 2-9 having an epoxy group corresponding to the other R 3 in formula (1) is obtained.
  • Intermediate compound 2-10 can be produced using the method shown below, and can be produced by using intermediate compound 2-10 in place of intermediate compound 2-2 in the seventh production method.
  • a fluorine-based compound is prepared in which hydroxymethyl groups (-CH 2 OH) are arranged at both ends of a perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1).
  • the hydroxyl group of the hydroxymethyl group located at one end of the fluorine-based compound is reacted with a compound having a leaving group and a protected hydroxyl group corresponding to one R 3 in formula (1).
  • the generated compound is reacted with a compound having a leaving group and a protected hydroxyl group corresponding to the other R 3 in formula (1).
  • one end of the perfluoropolyether chain corresponding to R 2 at the center of the molecule in formula (1) has a structure and a leaving group corresponding to one R 3 in formula (1), and the other end has a leaving group.
  • An intermediate compound 2-10 having a structure corresponding to the other R 3 in formula (1) and a leaving group at the end is obtained.
  • the magnetic recording medium lubricant of this embodiment contains a fluorine-containing ether compound represented by the above formula (1).
  • the lubricant of this embodiment may be made of known materials used as lubricant materials as long as the properties of the fluorine-containing ether compound represented by formula (1) are not impaired. They can be mixed and used depending on the situation.
  • known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco), and the like.
  • the known material used in combination with the lubricant of this embodiment preferably has a number average molecular weight of 1,000 to 10,000.
  • the fluorine-containing ether compound represented by the above formula (1) in the lubricant of this embodiment contains other materials of the fluorine-containing ether compound represented by the above formula (1)
  • the fluorine-containing ether compound represented by the above formula (1) in the lubricant of this embodiment The content is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.
  • the lubricant of this embodiment contains the fluorine-containing ether compound represented by the above formula (1), it is possible to form a lubricant layer that has excellent flying stability and is highly effective in suppressing pickup.
  • the magnetic recording medium of this embodiment has at least a magnetic layer, a protective layer, and a lubricating layer provided in this order on a substrate.
  • one or more underlayers can be provided between the substrate and the magnetic layer as necessary.
  • at least one of an adhesion layer and a soft magnetic layer may be provided between the underlayer and the substrate.
  • FIG. 1 is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.
  • the magnetic recording medium 10 of this embodiment includes, on a substrate 11, an adhesion layer 12, a soft magnetic layer 13, a first underlayer 14, a second underlayer 15, a magnetic layer 16, a protective layer 17, It has a structure in which lubricating layers 18 are sequentially provided.
  • substrate for example, a nonmagnetic substrate in which a film made of NiP or NiP alloy is formed on a base made of metal or alloy material such as Al or Al alloy can be used. Further, as the substrate 11, a nonmagnetic substrate made of a nonmetallic material such as glass, ceramics, silicon, silicon carbide, carbon, or resin may be used, or NiP or a NiP alloy may be used on a substrate made of these nonmetallic materials. A nonmagnetic substrate having a film formed thereon may also be used.
  • the adhesion layer 12 prevents the progress of corrosion of the substrate 11 that occurs when the substrate 11 and the soft magnetic layer 13 provided on the adhesion layer 12 are placed in contact with each other.
  • the material of the adhesion layer 12 can be appropriately selected from, for example, Cr, Cr alloy, Ti, Ti alloy, CrTi, NiAl, AlRu alloy, etc.
  • the adhesion layer 12 can be formed by, for example, a sputtering method.
  • the soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer made of a Ru film, and a second soft magnetic film are laminated in this order. That is, the soft magnetic layer 13 has a structure in which the soft magnetic films above and below the intermediate layer are coupled by anti-ferro coupling (AFC) by sandwiching an intermediate layer made of a Ru film between two soft magnetic films. It is preferable to have.
  • AFC anti-ferro coupling
  • the material for the first soft magnetic film and the second soft magnetic film examples include CoZrTa alloy and CoFe alloy. It is preferable that Zr, Ta, or Nb be added to the CoFe alloy used for the first soft magnetic film and the second soft magnetic film. This promotes amorphization of the first soft magnetic film and the second soft magnetic film. As a result, it becomes possible to improve the orientation of the first underlayer (seed layer) and to reduce the flying height of the magnetic head.
  • the soft magnetic layer 13 can be formed by, for example, a sputtering method.
  • the first underlayer 14 is a layer that controls the orientation and crystal size of the second underlayer 15 and magnetic layer 16 provided thereon.
  • Examples of the first underlayer 14 include a Cr layer, a Ta layer, a Ru layer, a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, a CrTi alloy layer, and the like.
  • the first base layer 14 can be formed by, for example, a sputtering method.
  • the second underlayer 15 is a layer that controls the orientation of the magnetic layer 16 to be good.
  • the second base layer 15 is preferably a layer made of Ru or Ru alloy.
  • the second base layer 15 may be a single layer or may be a plurality of layers. When the second base layer 15 is composed of multiple layers, all the layers may be composed of the same material, or at least one layer may be composed of different materials.
  • the second base layer 15 can be formed by, for example, a sputtering method.
  • the magnetic layer 16 is made of a magnetic film whose axis of easy magnetization is perpendicular or horizontal to the substrate surface.
  • the magnetic layer 16 is a layer containing Co and Pt.
  • the magnetic layer 16 may be a layer containing oxide, Cr, B, Cu, Ta, Zr, etc. to improve SNR characteristics. Examples of the oxide contained in the magnetic layer 16 include SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO 2 .
  • the magnetic layer 16 may be composed of one layer, or may be composed of a plurality of magnetic layers made of materials with different compositions.
  • the first magnetic layer contains Co, Cr, and Pt, and is further oxidized. It is preferable to have a granular structure made of a material containing substances.
  • the oxide contained in the first magnetic layer it is preferable to use, for example, an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, or the like. Among them, TiO 2 , Cr 2 O 3 , SiO 2 and the like can be particularly preferably used.
  • the first magnetic layer is preferably made of a composite oxide containing two or more types of oxides.
  • Cr 2 O 3 --SiO 2 , Cr 2 O 3 --TiO 2 , SiO 2 --TiO 2 and the like can be particularly preferably used.
  • the first magnetic layer contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides. can be included.
  • the same material as the first magnetic layer can be used for the second magnetic layer.
  • the second magnetic layer has a granular structure.
  • the third magnetic layer preferably has a non-granular structure made of a material containing Co, Cr, and Pt and no oxide.
  • the third magnetic layer contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn in addition to Co, Cr, and Pt. be able to.
  • the magnetic layer 16 When the magnetic layer 16 is formed of a plurality of magnetic layers, it is preferable to provide a non-magnetic layer between adjacent magnetic layers.
  • the magnetic layer 16 consists of three layers: a first magnetic layer, a second magnetic layer, and a third magnetic layer, there is a gap between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer. It is preferable to provide a nonmagnetic layer between them.
  • the nonmagnetic layer provided between adjacent magnetic layers of the magnetic layer 16 is, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 is Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Represents one or more elements selected from Ge, Si, O, N, W, Mo, Ti, V, and B), etc. can be suitably used.
  • an alloy material containing an oxide, a metal nitride, or a metal carbide for the nonmagnetic layer provided between adjacent magnetic layers of the magnetic layer 16.
  • the oxide for example, SiO 2 , Al 2 O 3 , Ta 2 O 5 , Cr 2 O 3 , MgO, Y 2 O 3 , TiO 2 or the like can be used.
  • the metal nitride for example, AlN, Si 3 N 4 , TaN, CrN, etc. can be used.
  • the metal carbide for example, TaC, BC, SiC, etc. can be used.
  • the nonmagnetic layer can be formed by, for example, a sputtering method.
  • the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer in which the axis of easy magnetization is perpendicular to the substrate surface.
  • the magnetic layer 16 may be a magnetic layer for longitudinal magnetic recording.
  • the magnetic layer 16 may be formed by any conventionally known method, such as vapor deposition, ion beam sputtering, and magnetron sputtering.
  • the magnetic layer 16 is usually formed by a sputtering method.
  • Protective layer 17 protects magnetic layer 16 .
  • the protective layer 17 may be composed of one layer or may be composed of multiple layers.
  • a carbon-based protective layer can be preferably used, and an amorphous carbon protective layer is particularly preferable. It is preferable that the protective layer 17 is a carbon-based protective layer because the interaction with the polar groups (especially hydroxyl groups) contained in the fluorine-containing ether compound in the lubricating layer 18 is further enhanced.
  • the adhesion between the carbon-based protective layer and the lubricating layer 18 can be achieved by using hydrogenated carbon and/or nitrogenated carbon as the carbon-based protective layer and adjusting the hydrogen content and/or nitrogen content in the carbon-based protective layer. It is controllable.
  • the hydrogen content in the carbon-based protective layer is preferably 3 at.% to 20 at.% when measured by hydrogen forward scattering (HFS).
  • the nitrogen content in the carbon-based protective layer is preferably 4 atomic % to 15 atomic % when measured by X-ray photoelectron spectroscopy (XPS).
  • the hydrogen and/or nitrogen contained in the carbon-based protective layer does not need to be uniformly contained throughout the carbon-based protective layer.
  • the carbon-based protective layer is preferably a compositionally graded layer in which the protective layer 17 on the lubricating layer 18 side contains nitrogen and the protective layer 17 on the magnetic layer 16 side contains hydrogen. In this case, the adhesion between the magnetic layer 16 and lubricating layer 18 and the carbon-based protective layer is further improved.
  • the thickness of the protective layer 17 is preferably 1 nm to 7 nm. When the thickness of the protective layer 17 is 1 nm or more, sufficient performance as the protective layer 17 can be obtained. It is preferable that the thickness of the protective layer 17 is 7 nm or less from the viewpoint of making the protective layer 17 thinner.
  • a sputtering method using a target material containing carbon As a method for forming the protective layer 17, a sputtering method using a target material containing carbon, a CVD (chemical vapor deposition) method using a hydrocarbon raw material such as ethylene or toluene, an IBD (ion beam deposition) method, etc. can be used. can.
  • a carbon-based protective layer as the protective layer 17 it can be formed by, for example, a DC magnetron sputtering method.
  • the amorphous carbon protective layer formed by plasma CVD has a uniform surface and low roughness.
  • Lubricating layer 18 prevents contamination of magnetic recording medium 10. Furthermore, the lubricating layer 18 reduces the frictional force of the magnetic head of the magnetic recording/reproducing device that slides on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10.
  • the lubricating layer 18 is formed on and in contact with the protective layer 17, as shown in FIG.
  • the lubricant layer 18 is formed by applying the magnetic recording medium lubricant of the above-described embodiment onto the protective layer 17. Therefore, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.
  • the lubricating layer 18 is bonded to the protective layer 17 with a high bonding force, especially when the protective layer 17 disposed below the lubricating layer 18 is a carbon-based protective layer. As a result, even if the lubricating layer 18 is thin, it is easy to obtain a magnetic recording medium 10 in which the surface of the protective layer 17 is coated with a high coverage rate, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented. .
  • the average thickness of the lubricating layer 18 is preferably 0.5 nm (5 ⁇ ) to 2.0 nm (20 ⁇ ), more preferably 0.5 nm (5 ⁇ ) to 1.2 nm (12 ⁇ ).
  • the average thickness of the lubricant layer 18 is 0.5 nm or more, the lubricant layer 18 does not have an island shape or a mesh shape and is formed with a uniform thickness. Therefore, the surface of the protective layer 17 can be covered with the lubricating layer 18 at a high coverage rate. Further, by setting the average thickness of the lubricant layer 18 to 2.0 nm or less, the lubricant layer 18 can be made sufficiently thin, and the flying height of the magnetic head can be made sufficiently small.
  • Method for forming a lubricating layer As a method for forming the lubricating layer 18, for example, a magnetic recording medium in the process of being manufactured in which each layer up to the protective layer 17 is formed on the substrate 11 is prepared, and a lubricating layer forming solution is applied onto the protective layer 17.
  • a method of drying is a method of drying.
  • the lubricant layer forming solution can be obtained by dispersing and dissolving the magnetic recording medium lubricant of the above-described embodiment in a solvent as necessary to obtain a viscosity and concentration suitable for the coating method.
  • the solvent used in the lubricating layer forming solution include fluorine-based solvents such as Vertrell (registered trademark) XF (trade name, manufactured by DuPont Mitsui Fluorochemicals Co., Ltd.).
  • the method for applying the lubricant layer forming solution is not particularly limited, and examples thereof include a spin coating method, a spray method, a paper coating method, a dipping method, and the like.
  • the dip method for example, the method shown below can be used.
  • the substrate 11 on which each layer up to the protective layer 17 has been formed is immersed in a lubricating layer forming solution placed in a dipping tank of a dip coater.
  • the substrate 11 is pulled up from the immersion bath at a predetermined speed.
  • the lubricating layer forming solution is applied to the surface of the protective layer 17 of the substrate 11.
  • the lubricating layer forming solution can be uniformly applied to the surface of the protective layer 17, and the lubricating layer 18 can be formed on the protective layer 17 with a uniform thickness.
  • the substrate 11 on which the lubricant layer 18 is formed is subjected to heat treatment.
  • the heat treatment temperature is preferably 100°C to 180°C, more preferably 100°C to 160°C.
  • the heat treatment temperature is 100° C. or higher, the effect of improving the adhesion between the lubricating layer 18 and the protective layer 17 can be sufficiently obtained.
  • the heat treatment time can be adjusted as appropriate depending on the heat treatment temperature, and is preferably 10 minutes to 120 minutes.
  • the lubricant layer 18 may be irradiated with ultraviolet (UV) light before or after heat treatment.
  • UV ultraviolet
  • the magnetic recording medium 10 of this embodiment has at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 provided in this order on a substrate 11.
  • a lubricating layer 18 containing the above-mentioned fluorine-containing ether compound is formed on and in contact with the protective layer 17 .
  • This lubricating layer 18 has good flying stability and is highly effective in suppressing pickup. Therefore, the magnetic recording medium 10 of this embodiment has excellent reliability and durability. Therefore, the magnetic recording medium 10 of this embodiment can have a low flying height of the magnetic head (for example, 10 nm or less), and is stable for a long period of time even under harsh environments associated with diversification of applications. and it works. Therefore, the magnetic recording medium 10 of this embodiment is particularly suitable as a magnetic disk mounted in a magnetic disk device of the LUL (Load/Unload) system.
  • Example 1 A compound represented by the above formula (AA) was obtained by the method shown below. (first reaction) HOCH 2 CF 2 O (CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH (in the formula, h indicating the average degree of polymerization is 4.5, i indicating the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) 20 g, and 4.12 g of the compound represented by the above formula (5-1).
  • the compound represented by formula (5-1) was synthesized by protecting the hydroxyl group of ethylene glycol monoallyl ether using dihydropyran and then oxidizing it with m-chloroperbenzoic acid.
  • reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate.
  • the organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering off the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 9.61 g of a compound represented by the following formula (11) as intermediate compound 1-1.
  • Rf 1 in formula (11) is a PFPE chain represented by the above formula (4-1); in Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization. represents 4.5; THP represents a tetrahydropyranyl group.
  • reaction solution obtained after the reaction was returned to room temperature, 50 g of 10% hydrogen chloride/methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature for 4 hours. Thereafter, the reaction solution was transferred little by little into a separatory funnel containing 100 mL of saturated aqueous sodium bicarbonate solution, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate solution, and 100 mL of brine in this order, and dehydrated with anhydrous sodium sulfate.
  • Example 2 A compound represented by the above formula (AB) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-2) was used instead of the compound represented by formula (5-1), and compound (AB) (formula (AB ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-2) was synthesized by protecting one hydroxyl group of 1,3-propanediol using dihydropyran and then reacting it with epibromohydrin.
  • Example 3 A compound represented by the above formula (AC) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-3) was used instead of the compound represented by formula (5-1), and compound (AC) (formula (AC ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-3) was synthesized by protecting the hydroxyl group of 3-buten-1-ol using dihydropyran and then oxidizing it with m-chloroperbenzoic acid.
  • Example 4 A compound represented by the above formula (AD) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-4) was used instead of the compound represented by formula (5-1), and compound (AD) (formula (AD ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-4) is obtained by reacting the hydroxyl group of 3-buten-1-ol with 2-(2-bromoethoxy)tetrahydro-2H-pyran and then reacting with m-chloroperbenzoic acid. Synthesized by oxidation.
  • Example 5 A compound represented by the above formula (AE) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), and compound (AE) (formula (AE ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-5) is obtained by subjecting the compound represented by formula (5-1) to an addition reaction with allyl alcohol, and then protecting the hydroxyl group of the resulting compound using dihydropyran. , further oxidized with m-chloroperbenzoic acid.
  • Example 6 A compound represented by the above formula (AF) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-6) was used instead of the compound represented by formula (5-1), and compound (AF) (formula (AF ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-6) can be obtained by subjecting the compound represented by formula (5-3) to an addition reaction with allyl alcohol, and then protecting the hydroxyl group of the resulting compound using dihydropyran. , further oxidized with m-chloroperbenzoic acid.
  • Example 7 A compound represented by the above formula (AG) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-7) was used instead of the compound represented by formula (5-1), and compound (AG) (formula (AG ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-7) can be obtained by subjecting the compound represented by formula (5-1) to an addition reaction with 3-buten-1-ol, and then converting the hydroxyl group of the resulting compound into dihydropyran. It was synthesized by protecting the compound using m-chloroperbenzoic acid and further oxidizing it with m-chloroperbenzoic acid.
  • Example 8 A compound represented by the above formula (AH) was obtained by the method shown below. (first reaction) In the same manner as the first reaction of Example 1, a compound represented by formula (11) was obtained as intermediate compound 1a.
  • Rf 1 in formula (12) is a PFPE chain represented by the above formula (4-1); in Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization. represents 4.5; THP represents a tetrahydropyranyl group.
  • reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate.
  • the organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering off the drying agent, the filtrate was concentrated, and the residue was oxidized with m-chloroperbenzoic acid, and then purified by silica gel column chromatography to obtain intermediate compound 1-4, which is represented by the following formula (13). 6.48 g of compound was obtained.
  • Rf 1 in formula (13) is a PFPE chain represented by the above formula (4-1); in Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization. represents 4.5; THP represents a tetrahydropyranyl group.
  • reaction solution obtained after the reaction was returned to room temperature, 50 g of 10% hydrogen chloride/methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature for 4 hours. Thereafter, the reaction solution was transferred little by little into a separatory funnel containing 100 mL of saturated aqueous sodium bicarbonate solution, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate solution, and 100 mL of brine in this order, and dehydrated with anhydrous sodium sulfate.
  • Example 9 A compound represented by the above formula (AI) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-8) was used instead of the compound represented by formula (5-1), and compound (AI) (formula (AI ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-8) was synthesized by protecting one hydroxyl group of 1,6-hexanediol using dihydropyran and then reacting it with epibromohydrin.
  • Example 10 A compound represented by the above formula (AJ) was obtained by the method shown below. The same operation as in Example 1 was performed except that the compound represented by formula (5-9) was used instead of the compound represented by formula (5-1), and compound (AJ) (formula (AJ ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-9) was synthesized by protecting the hydroxyl group of 7-octen-1-ol using dihydropyran and then oxidizing it with m-chloroperbenzoic acid.
  • Example 11 A compound represented by the above formula (AK) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-10) was used instead of the compound represented by formula (5-1), and compound (AK) (formula (AK ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-10) is obtained by protecting the hydroxyl group of 2-bromoethanol using dihydropyran, and then reacting it with 5-hexen-1-ol, and then reacting it with m-chloroperbenzoic acid. Synthesized by oxidation.
  • Example 12 A compound represented by the above formula (AL) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (5-11) was used instead of the compound represented by formula (5-1), and compound (AL) (formula (AL ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-11) was synthesized by reacting N-(2-hydroxyethyl)acetamide and epibromohydrin.
  • Example 13 A compound represented by the above formula (AM) was obtained by the method shown below. The same operation as in Example 1 was performed except that the compound represented by formula (5-12) was used instead of the compound represented by formula (5-1), and compound (AM) (formula (AM ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (5-12) was synthesized by reacting 2-cyanoethanol and epibromohydrin.
  • Example 14 A compound represented by the above formula (AN) was obtained by the method shown below. The same operation as in Example 1 was performed except that the compound represented by formula (7-2) was used instead of the compound represented by formula (7-1), and compound (AN) (formula (AN ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (7-2) was synthesized by oxidizing allyl glycidyl ether with m-chloroperbenzoic acid.
  • Example 15 A compound represented by the above formula (AO) was obtained by the method shown below. In place of the compound represented by formula (5-1), a compound represented by formula (5-5) is used, and in place of the compound represented by formula (7-1), formula (7-2) is used. The same operation as in Example 1 was carried out except that the compound represented by the formula (AO) was used, and Rf 1 in the formula (AO) was a PFPE chain represented by the above formula (4-1). In the two Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4.5).
  • Example 16 A compound represented by the above formula (AP) was obtained by the method shown below. The same operation as in Example 1 was carried out except that the compound represented by formula (7-3) was used instead of the compound represented by formula (7-1), and compound (AP) (formula (AP ) in Rf 1 is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4. .5) was obtained.
  • the compound represented by formula (7-3) is obtained by reacting one molecule of epibromohydrin with two molecules of allyl alcohol, and then protecting the secondary hydroxyl group of the compound produced after the reaction using dihydropyran. It was synthesized by further oxidizing with m-chloroperbenzoic acid.
  • Example 17 A compound represented by the above formula (AQ) was obtained by the method shown below. Instead of the compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH, HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) j Example except that a compound represented by CF 2 CF 2 CH 2 OH (j indicating the average degree of polymerization in the formula is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) was used. Perform the same operation as in 1 to obtain compound (AQ) (Rf 2 in formula (AQ) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j indicating the average degree of polymerization is 4.5) was obtained.
  • Example 18 A compound represented by the above formula (AR) was obtained by the method shown below. Instead of the compound represented by HOCH 2 CF 2 O (CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH, HOCH 2 CF 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) k CF 2 CF 2 CF 2 CH 2 OH (k indicating the average degree of polymerization in the formula is 3.0) (number average molecular weight 1000, molecular weight distribution 1.1) was used. The same operation as in Example 1 was carried out except that the compound (AR) (Rf 3 in formula (AR) is a PFPE chain represented by the above formula ( 4-3 ). (k indicating the degree of polymerization is 3.0) was obtained.
  • Example 19 A compound represented by the above formula (AS) was obtained by the method shown below. (first reaction) In the same manner as the first reaction of Example 1, a compound represented by formula (11) was obtained as intermediate compound 1-2.
  • Ts represents a tosyl group (p-toluenesulfonyl group).
  • reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate.
  • the organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering off the desiccant, the filtrate was concentrated, and the residue was oxidized with m-chloroperbenzoic acid, and then purified by silica gel column chromatography to obtain intermediate compound 1-3, which is represented by the following formula (15). 7.22 g of compound was obtained.
  • Rf 1 in formula (15) is a PFPE chain represented by the above formula (4-1); in Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization. represents 4.5; THP represents a tetrahydropyranyl group.
  • THP represents a tetrahydropyranyl group.
  • reaction solution obtained after the reaction was returned to room temperature, 50 g of 10% hydrogen chloride/methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature for 4 hours. Thereafter, the reaction solution was transferred little by little into a separatory funnel containing 100 mL of saturated aqueous sodium bicarbonate solution, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate solution, and 100 mL of brine in this order, and dehydrated with anhydrous sodium sulfate.
  • Example 20 A compound represented by the above formula (AT) was obtained by the method shown below. The same procedure was carried out except that in the first reaction of Example 19, intermediate compound 1-2 was synthesized using a compound represented by the following formula (17) instead of the compound represented by formula (5-1). The same operation as in Example 19 was performed, and compound (AT) (Rf 1 in formula (AT) is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , the average degree of polymerization was 3.28g of 3.28g of 3.28g of the product was obtained (h represents 4.5, and i represents the average degree of polymerization 4.5).
  • THP represents a tetrahydropyranyl group.
  • the compound represented by formula (17) was synthesized by protecting the hydroxyl group of allyl alcohol using dihydropyran and then oxidizing it with m-chloroperbenzoic acid.
  • Example 21 A compound represented by the above formula (AU) was obtained by the method shown below. The same operation as in Example 1 was performed except that the compound represented by formula (5-13) was used instead of the compound represented by formula (5-1) in Example 1, and compound (AU) (Rf 1 in formula (AU) is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h indicating the average degree of polymerization is 4.5, and the average degree of polymerization is 2.04g of 4.5 was obtained.
  • the compound represented by formula (5-13) was synthesized by reacting salicylamide and epibromohydrin.
  • Example 22 A compound represented by the above formula (AV) was obtained by the method shown below. The same operation as in Example 1 was performed except that the compound represented by formula (5-14) was used instead of the compound represented by formula (5-1) in Example 1, and compound (AV) (Rf 1 in formula (AV) is a PFPE chain represented by the above formula (4-1). In the two Rf 1s , h indicating the average degree of polymerization is 4.5, and the average degree of polymerization is 2.21g of 4.5 was obtained.
  • the compound represented by formula (5-14) was synthesized by reacting 3-cyanophenol and epibromohydrin.
  • Example 23 A compound represented by the above formula (BA) was obtained by the method shown below. The same operation as in Example 1 was performed except that the compound represented by the following formula (18) was used instead of the compound represented by the formula (7-1), and the compound (BA) (formula (BA) Rf 1 therein is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4.5. 5) was obtained.
  • Rf 1 in formula (18) is a PFPE chain represented by the above formula (4-1); in Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization. represents 4.5.
  • the compound represented by formula (18) is HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH (in the formula, h indicating the average degree of polymerization is 4.5. (and i indicating the average degree of polymerization is 4.5.) (number average molecular weight 1000, molecular weight distribution 1.1) and the compound represented by formula (9-1) are reacted. After that, it was synthesized by oxidizing with m-chloroperbenzoic acid.
  • Example 24 A compound represented by the above formula (BB) was obtained by the method shown below. The same operation as in Example 23 was carried out except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), and compound (BB) (formula (BB Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Example 25 A compound represented by the above formula (BC) was obtained by the method shown below. The same operation as in Example 23 was carried out except that the compound represented by formula (5-3) was used instead of the compound represented by formula (5-1), and compound (BC) (formula (BC Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Example 26 A compound represented by the above formula (BD) was obtained by the method shown below. The same operation as in Example 23 was performed except that the compound represented by formula (5-4) was used instead of the compound represented by formula (5-1), and compound (BD) (formula (BD Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Example 27 A compound represented by the above formula (BE) was obtained by the method shown below. The same operation as in Example 23 was performed except that the compound represented by formula (5-11) was used instead of the compound represented by formula (5-1), and compound (BE) (formula (BE Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Example 28 A compound represented by the above formula (BF) was obtained by the method shown below. The same operation as in Example 23 was performed except that the compound represented by formula (5-12) was used instead of the compound represented by formula (5-1), and compound (BF) (formula (BF Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Example 29 A compound represented by the above formula (BG) was obtained by the method shown below. The same operation as in Example 23 was carried out except that the compound represented by formula (9-2) was used instead of the compound represented by formula (9-1), and compound (BG) (formula (BG Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Example 30 A compound represented by the above formula (BH) was obtained by the method shown below. The same operation as in Example 23 was carried out except that the compound represented by formula (9-3) was used instead of the compound represented by formula (9-1), and compound (BH) (formula (BH Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • the compound represented by formula (9-3) is produced by reacting one molecule of epibromohydrin with two molecules of allyl alcohol, and then protecting the secondary hydroxyl group of the resulting compound using dihydropyran. was synthesized by oxidizing the carbon-carbon double bond of with m-chloroperbenzoic acid.
  • Example 31 A compound represented by the above formula (BI) was obtained by the method shown below. The same operation as in Example 23 was carried out except that the compound represented by the following formula (19) was used instead of the compound represented by formula (18), and compound (BI) (in formula (BI)) Rf 1 is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4.5. ) was obtained.
  • Rf 1 in formula (19) is a PFPE chain represented by the above formula (4-1); in Rf 1 , h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization. represents 4.5.
  • the compound represented by formula (19) was produced by the method shown below.
  • HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH in the formula, h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. 5) (number average molecular weight 1000, molecular weight distribution 1.1) was reacted with 1,3-butadiene monoepoxide.
  • the generated compound was reacted with epibromohydrin.
  • m-chloroperbenzoic acid was applied to the generated compound to oxidize the carbon-carbon double bond, thereby synthesizing the compound.
  • Example 32 A compound represented by the above formula (BJ) was obtained by the method shown below. Instead of the compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH, HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) j Example except that a compound represented by CF 2 CF 2 CH 2 OH (j indicating the average degree of polymerization in the formula is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) was used. Perform the same operation as in 23 to obtain compound (BJ) (Rf 2 in formula (BJ) is a PFPE chain represented by the above formula (4-2). In the three Rf 2 , the average degree of polymerization is shown. j represents 4.5) was obtained.
  • Example 33 A compound represented by the above formula (BK) was obtained by the method shown below. The same operation as in Example 29 was carried out except that the compound represented by formula (5-12) was used instead of the compound represented by formula (5-1), and compound (BK) (formula (BK Rf 1 in ) is a PFPE chain represented by the above formula (4-1). In the three Rf 1s , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4. .5) was obtained.
  • Rf 1 in formula (ZA) is a PFPE chain represented by the above formula (4-1); in the two Rf 1s , h indicating the average degree of polymerization represents 7.0, and the average degree of polymerization is The i shown here represents 0.)
  • Rf 1 in formula (ZB) is a PFPE chain represented by the above formula (4-1); in the two Rf 1s , h indicating the average degree of polymerization represents 4.5, and the average degree of polymerization is The i shown represents 4.5.
  • Rf 1 in formula (ZC) is a PFPE chain represented by the above formula (4-1); in the two Rf 1s , h indicating the average degree of polymerization represents 4.5, and the average degree of polymerization is The i shown represents 4.5.
  • Rf 2 in formula (ZD) is a PFPE chain represented by the above formula (4-2); in the two Rf 2 , j indicating the average degree of polymerization represents 4.5.
  • Rf 1 in formula (ZE) is a PFPE chain represented by the above formula (4-1); in the two Rf 1s , h indicating the average degree of polymerization is 4.5, and the average degree of polymerization is The i shown represents 4.5.
  • Rf 1 in formula (ZF) is a PFPE chain represented by the above formula (4-1); in the two Rf 1s , h indicating the average degree of polymerization represents 4.5, and the average degree of polymerization is The i shown represents 4.5.
  • Rf 1 in formula (ZG) is a PFPE chain represented by the above formula (4-1); in the three Rf 1s , h indicating the average degree of polymerization represents 7.0, and the average degree of polymerization is The i shown here represents 0.)
  • Rf 1 in formula (ZH) is a PFPE chain represented by the above formula (4-1); in the two Rf 1s , h indicating the average degree of polymerization represents 4.5, and the average degree of polymerization is The i shown represents 4.5.
  • Rf 1 in formula (ZI) is a PFPE chain represented by the above formula (4-1); in the three Rf 1s , h indicating the average degree of polymerization represents 4.5, and the average degree of polymerization is The i shown represents 4.5.
  • lubricating layer forming solutions were prepared using the compounds obtained in Examples 1 to 33 and Comparative Examples 1 to 9 by the method shown below. Then, using the obtained lubricant layer forming solution, lubricant layers of magnetic recording media were formed by the method shown below to obtain magnetic recording media of Examples 1 to 33 and Comparative Examples 1 to 9.
  • “Lubricant layer forming solution” The compounds obtained in Examples 1 to 33 and Comparative Examples 1 to 9 were each dissolved in a fluorine-based solvent, Bartrel (registered trademark) The solution was diluted with Bartrel XF so that the film thickness would be 9.0 ⁇ to 9.5 ⁇ when mixed, and a solution for forming a lubricating layer was prepared.
  • Magnetic recording medium A magnetic recording medium was prepared in which an adhesive layer, a soft magnetic layer, a first underlayer, a second underlayer, a magnetic layer, and a protective layer were sequentially provided on a substrate having a diameter of 65 mm.
  • the protective layer was made of carbon.
  • the lubricating layer forming solutions of Examples 1 to 33 and Comparative Examples 1 to 9 were applied by dipping onto the protective layer of the magnetic recording medium in which each layer up to the protective layer was formed. Note that the dipping method was performed under the conditions of a dipping speed of 10 mm/sec, a dipping time of 30 sec, and a pulling rate of 1.2 mm/sec.
  • the magnetic recording medium coated with the lubricant layer forming solution is placed in a constant temperature bath, and heat treatment is performed at 120°C for 10 days to remove the solvent in the lubricant layer forming solution and improve the adhesion between the protective layer and the lubricant layer.
  • a lubricating layer was formed on the protective layer by performing this for a few minutes, and a magnetic recording medium was obtained.
  • the thickness of the lubricating layer of the magnetic recording media of Examples 1 to 33 and Comparative Examples 1 to 9 thus obtained was measured using a Fourier transform infrared spectrophotometer (FT-IR, trade name: Nicolet iS50, Thermo (manufactured by Fisher Scientific). The results are shown in Tables 2 and 3.
  • FT-IR Fourier transform infrared spectrophotometer
  • the glide test examines whether there are any protrusions on the surface of the magnetic recording medium. In other words, when a magnetic head is used to read and write information on a magnetic recording medium, if there is a protrusion on the surface of the magnetic recording medium that is higher than the flying height (distance between the magnetic recording medium and the magnetic head), the magnetic head This can cause damage to the magnetic head or defects to the magnetic recording medium due to collision with the protrusion. In the glide test, 50 magnetic recording media are inspected for the presence or absence of protrusions with a height greater than the flying height on the surface.
  • the interval between the magnetic recording head for inspection and the magnetic recording medium is set to 0.25 microinch, the magnetic head for inspection is moved over the magnetic recording medium, and the magnetic recording medium is removed from the magnetic recording head for inspection. If a signal caused by a collision with a protrusion on the surface of the magnetic recording medium was output, the magnetic recording medium was determined to be defective, and otherwise, it was determined to be acceptable. Then, evaluation was made using the number of magnetic recording media that were determined to be acceptable among the 50 magnetic recording media.
  • R 1 and R 4 placed at the ends of the chain structure are terminal groups represented by any of formulas (3-1) to (3-4), and the adjacent part A compound (AA ) ⁇ (AV), (BA) ⁇ (BK)
  • the magnetic recording media of Examples 1 to 33 were evaluated as either A+, A, or B in the flying stability test and pickup characteristic test, and the overall All evaluations were A or B. From this, it was confirmed that the lubricating layers of the magnetic recording media of Examples 1 to 33 had good flying stability and a high pick-up suppressing effect.
  • Example 1 using compounds (AA) to (AD), (AL) to (AN), (AQ) to (AV), (BA), (BC) to (BG), (BJ), and (BK)
  • the magnetic recording media of ⁇ 4, 12 ⁇ 14, 17 ⁇ 23, 25 ⁇ 29, 32, and 33 were evaluated as either A+ or A in the flying stability test and pickup characteristic test, and the overall evaluation was A. Ta.
  • Compounds (AA) to (AD), (AL) to (AN), (AQ) to (AT), (BA), (BC) to (BG), (BJ), and (BK) have x number of R
  • the number of hydroxyl groups contained in 3 is two each, the number of polar groups contained in R 1 and R 4 is two each, and R 1 and R 4 are respectively represented by formulas (3-1) to (3- 3), and the alkylene chain in the main chain portion of R 1 and R 4 is not too long (the sum of p and r in formula (3-1) is 3 or less, in formula (3-2)) t is 4 or less, and the total number of carbon atoms and oxygen atoms in Y in formula (3-3) is 3 or less).
  • the number of hydroxyl groups contained in R 3 is two
  • the number of polar groups contained in R 1 and R 4 is two, respectively, and R 1 and R 4 is expressed by equation (3-4).
  • Example 12 using compounds (AL), (AU), and (BE) in which R 3 is the formula (2-1) and R 1 and R 4 contain a group having an amide bond
  • the evaluation of the flying stability test was A
  • the evaluation of the pick-up characteristic test was A+
  • the evaluation of the pick-up characteristic test was A+, which was an excellent result.
  • the levitation stability test The evaluation was A+
  • the evaluation of the pickup characteristic test was A, which was an excellent result.
  • the strength of the interaction between R 1 and R 4 and the active site on the protective layer and the strength of the interaction between R 3 and the active site on the protective layer were It is presumed that the balance was appropriate.
  • Comparative Examples 1 to 9 using Compounds (ZA) to (ZI) the evaluation in the floating stability test and the pickup characteristic test was C or D, and the overall evaluation was D. More specifically, Comparative Example 1 using compounds (ZA), (ZB), (ZH), and (ZI) in which the linking group arranged between adjacent perfluoropolyether chains contains only one hydroxyl group, In Nos. 2, 8, and 9, the results of the levitation stability test were D. This is because the number of hydroxyl groups in the linking group is insufficient, so sufficient interaction between the linking group and the protective layer cannot be obtained, and the central part of the fluorine-containing ether compound lifts up, causing the lubricating layer to lose its smoothness. This is thought to be due to
  • the lubricant for magnetic recording media containing the fluorine-containing ether compound of the present invention it is possible to form a lubricant layer that has good flying stability and is highly effective in suppressing pickup.
  • SYMBOLS 10 Magnetic recording medium, 11... Substrate, 12... Adhesion layer, 13... Soft magnetic layer, 14... First underlayer, 15... Second underlayer, 16... - Magnetic layer, 17... protective layer, 18... lubricating layer.

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