WO2024225106A1 - 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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WO2024225106A1
WO2024225106A1 PCT/JP2024/015067 JP2024015067W WO2024225106A1 WO 2024225106 A1 WO2024225106 A1 WO 2024225106A1 JP 2024015067 W JP2024015067 W JP 2024015067W WO 2024225106 A1 WO2024225106 A1 WO 2024225106A1
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formula
group
represented
compound
fluorine
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French (fr)
Japanese (ja)
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優 丹治
大輔 柳生
康平 嵯峨
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Resonac Corp
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Resonac Corp
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Priority to JP2024559431A priority patent/JPWO2024225106A1/ja
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    • 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
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
    • C07C255/11—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms containing cyano groups and singly-bound oxygen atoms bound to the same saturated acyclic carbon skeleton
    • C07C255/13—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms containing cyano groups and singly-bound oxygen atoms bound to the same saturated acyclic 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
    • C07C43/10—Saturated ethers of polyhydroxy compounds
    • C07C43/11—Polyethers containing —O—(C—C—O—)n units with ≤ 2 n≤ 10
    • 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
    • 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
    • C07C43/14—Unsaturated ethers
    • C07C43/178—Unsaturated 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
    • C08G65/02—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
    • 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
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/50—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing halogen
    • C10M105/54—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing halogen containing carbon, hydrogen, halogen and oxygen
    • 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
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/56—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen
    • 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
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/56—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen
    • C10M105/58—Amines, e.g. polyalkylene polyamines, quaternary amines
    • 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
    • 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
    • C10M107/40—Lubricating compositions characterised by the base-material being a macromolecular compound containing nitrogen
    • C10M107/44—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • 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
    • 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

Definitions

  • the present invention relates to a fluorine-containing ether compound, a lubricant for a magnetic recording medium, and a magnetic recording medium.
  • magnetic recording media include those in which a recording layer is formed on a substrate, and a protective layer such as carbon is formed on the recording layer.
  • the protective layer protects the information recorded on the recording layer and also improves the sliding properties of the magnetic head.
  • simply providing a protective layer on the recording layer does not provide sufficient durability for the magnetic recording medium. For this reason, a lubricant is generally applied to the surface of the protective layer to form a lubricating layer.
  • lubricants for use in forming a lubricating layer on a magnetic recording medium for example, those containing 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 including --CF 2 -- have been proposed.
  • Patent Documents 1 and 2 disclose fluorine- containing ether compounds in which a glycerin linking group (-O-CH 2 -CH (OH)-CH 2 -O-) and a terminal group which is an organic group having a polar group are bonded in this order to both ends of a perfluoropolyether chain via a methylene group (-CH 2 -).
  • Patent Document 3 discloses a fluorine-containing ether compound in which a linking group containing a structure (-O-CH 2 -CH (OH)-CH 2 -(CH 2 ) n -O-) in which a glycerin linking group has been increased in carbon atom via a methylene group (-CH 2 -) and an end group are bonded in this order to both ends of a perfluoropolyether chain.
  • Patent Document 4 discloses a fluorine-containing ether compound in which one or more glycerin structures are bonded to both ends of a perfluoropolyether chain via a methylene group (-CH 2 -).
  • the present invention was made in consideration of the above circumstances, and aims to provide a fluorine-containing ether compound that has excellent corrosion resistance, can form a lubricating layer that can suppress spin-off, and can be suitably used as a material for lubricants for magnetic recording media.
  • the present invention aims to provide a lubricant for magnetic recording media that contains the fluorine-containing ether compound of the present invention and is capable of forming a lubricating layer that has good corrosion resistance and can suppress spin-off.
  • the present invention aims to provide a magnetic recording medium that has a lubricating layer containing the fluorine-containing ether compound of the present invention, has good corrosion resistance, and can suppress spin-off.
  • the present invention includes the following aspects:
  • R2 is a perfluoropolyether chain.
  • R1 and R3 are terminal groups having 1 to 4 polar groups and 1 to 50 carbon atoms.
  • R1 and R3 may be the same or different.
  • At least one of R1 and R3 is a terminal group represented by the following formula (2).
  • X is a divalent organic group having 2 to 30 carbon atoms which may contain at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms.
  • X contains at least one carbon atom which is not bonded to any of the polar groups and the ether oxygen atoms.
  • l represents an integer of 1 to 3.
  • l's m each independently represents an integer of 1 to 6.
  • l's n each independently represents an integer of 1 to 6.
  • B represents an alkyl group which may have only one polar group, an organic group containing a carbon-carbon unsaturated bond, or a hydrogen atom.
  • p represents an integer of 0 to 3.
  • q represents an integer of 0 to 2.
  • r represents an integer of 0 to 5. The total value of p and r is 1 to 5.
  • D represents a polar group, a vinyl group, an ethynyl group, or an aryl group which may have a substituent.
  • s represents an integer of 0 to 2.
  • t represents an integer of 1 to 5.
  • u represents an integer of 1 to 3.
  • Each of the five E's independently represents a polar group, an alkoxy group having 1 to 8 carbon atoms, a halogeno group, or a hydrogen atom. However, when the five E's include a polar group, the number of polar groups among the five E's is 1.
  • R 2 in the formula (1) is a perfluoropolyether chain represented by the following formula (4): -(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 represent an average degree of polymerization and each independently represents 0 to 20.
  • w1 and w6 represent an average value representing the number of CF2 and each independently represents 1 to 3. There is no particular restriction on the arrangement order of the repeating units (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).)
  • R 2 in the formula (1) is any one selected from perfluoropolyether chains represented by the following formulas (4-1) to (4-4): -CF 2 -(OCF 2 CF 2 ) h -(OCF 2 ) i -OCF 2 - (4-1)
  • h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20.
  • j represents the average degree of polymerization and is 1 to 15.
  • k represents the average degree of polymerization and is 1 to
  • a lubricant for magnetic recording media comprising a fluorine-containing ether compound according to any one of [1] to [10].
  • a magnetic recording medium having at least a magnetic layer, a protective layer, and a lubricating layer sequentially provided on a substrate, the lubricating layer comprising a fluorine-containing ether compound according to any one of [1] to [10].
  • the fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is therefore suitable as a material for a lubricant for magnetic recording media.
  • the lubricant for magnetic recording media of the present invention contains the fluorine-containing ether compound of the present invention, and therefore can form a lubricating layer that has good corrosion resistance and can suppress spin-off.
  • the magnetic recording medium of the present invention has a lubricating layer that contains the fluorine-containing ether compound of the present invention.
  • the magnetic recording medium of the present invention has good corrosion resistance, can suppress spin-off, and is highly reliable and durable.
  • the magnetic recording medium of the present invention can have a thinner lubricating layer, which contributes to reducing magnetic spacing and further reduces the flying height of the magnetic head.
  • FIG. 1 is a schematic cross-sectional view showing one embodiment of a magnetic recording medium of the present invention.
  • fluorine-containing ether compounds having terminal groups containing polar groups such as hydroxyl groups have been preferably used as materials for lubricants for magnetic recording media (hereinafter sometimes abbreviated as "lubricants") that are applied to the surface of a protective layer.
  • the polar groups in the fluorine-containing ether compound not only bind to active sites on the protective layer and participate in interactions with the protective layer, but also participate in intramolecular and intermolecular interactions. If there are not enough polar groups involved in intermolecular interactions between fluorine-containing ether compounds, the fluorine-containing ether compound in the lubricating layer will easily scatter as the magnetic recording medium rotates, making spin-off more likely to occur.
  • the fluorine-containing ether compound must contain sufficient polar groups involved in interactions with the protective layer and intermolecular interactions so that it can form a lubricating layer with good corrosion resistance and suppressed spin-off.
  • the number of polar groups in the fluorine-containing ether compound is increased, the hydrophobicity of the lubricating layer containing it decreases, making it impossible to obtain sufficient corrosion resistance.
  • the inventors therefore conducted extensive research focusing on the strength of the polar groups contained in the fluorinated ether compound and the interactions between the polar groups. As a result, they came to the conclusion that at least a portion of the polar groups in the fluorinated ether compound should be hydroxyl groups of a 1,2-diol structure located at the end of the perfluoropolyether chain. In this case, as shown below, it is possible to ensure hydroxyl groups that can interact with the protective layer and hydroxyl groups that can participate in intermolecular interactions while suppressing the decrease in hydrophobicity caused by the hydroxyl groups contained in the 1,2-diol structure.
  • a 1,2-diol structure (-CH(OH)-CH 2 OH)
  • the carbon atoms to which hydroxyl groups are bonded are bonded to each other, so that the distance between the hydroxyl groups is short, and steric and electrostatic repulsion between the hydroxyl groups is likely to occur.
  • the two hydroxyl groups contained in the 1,2-diol structure are in an opposite conformation to the carbon atom to which the 1,2-diol structure is bonded. Therefore, the dipole moments generated by the two hydroxyl groups contained in the 1,2-diol structure cancel each other out, and an increase in the polarity of the entire fluorine-containing ether compound molecule is suppressed.
  • the distance between active points on the protective layer is sufficiently larger than the distance between hydroxyl groups contained in the 1,2-diol structure.
  • the two hydroxyl groups contained in the 1,2-diol structure are in an opposite conformation with respect to the carbon atom to which the 1,2-diol structure is bonded. Therefore, the two hydroxyl groups contained in the 1,2-diol structure are not in a direction approaching the protective layer at the same time, and only one of the two hydroxyl groups can interact with the active points on the protective layer. Therefore, the other of the two hydroxyl groups can participate in the intermolecular interaction between the fluorine-containing ether compounds.
  • the present inventors deliberately made some of the polar groups in the fluorinated ether compound hydroxyl groups having a 1,2-diol structure, thereby securing polar groups that can participate in intermolecular interactions between fluorinated ether compounds, and then considered that it would be sufficient to adjust the number of polar groups that can interact with active sites on the protective layer as necessary.
  • the present inventors have conducted extensive research into a fluorine-containing ether compound having a 1,2-diol structure at one or both ends of a perfluoropolyether chain, in order to improve the corrosion resistance of a lubricating layer containing this compound and to suppress spin-off.
  • a fluorine-containing ether compound may be obtained in which end groups having 1 to 50 carbon atoms and having 1 to 4 polar groups are arranged on both ends of a perfluoropolyether chain, and at least one of the two end groups contains at least one carbon atom which is not bonded to either a polar group or an ether oxygen atom and is an end group represented by formula (2) having a 1,2-diol structure, and have arrived at the present invention.
  • the number of polar groups is appropriate, and some of the polar groups are hydroxyl groups of a 1,2-diol structure arranged at the end of the perfluoropolyether chain, so that it is possible to suppress the decrease in hydrophobicity caused by the polar groups, while sufficiently securing hydroxyl groups that can interact with the protective layer and hydroxyl groups that can participate in intermolecular interactions.
  • the end group represented by formula (2) arranged at at least one end contains at least one carbon atom that is not bonded to either a polar group or an ether oxygen atom. Since this carbon atom has an extremely low affinity for water, it strongly hinders the interaction between the fluorine-containing ether compound molecule and water.
  • the fluorine-containing ether compound contains multiple polar groups, sufficient hydrophobicity can be obtained.
  • the movement of the above carbon atom is suppressed, it brings appropriate rigidity to the fluorine-containing ether compound molecule, suppresses intramolecular interactions between polar groups, and makes it easier for the polar group to participate in intermolecular interactions between fluorine-containing ether compounds.
  • the above-mentioned fluorine-containing ether compounds are able to maintain low polarity while ensuring the number of polar groups involved in the interaction with the protective layer, and have sufficient hydrophobicity.
  • lubricants containing them are less likely to absorb water, which causes corrosion, and have excellent corrosion resistance.
  • the above-mentioned fluorine-containing ether compounds easily generate polar groups that are not involved in either the interaction with the protective layer or the interaction within the molecule, and the polar groups easily form intermolecular interactions.
  • the fluorine-containing ether compounds are less likely to scatter as the magnetic recording medium rotates, and a lubricating layer with excellent spin-off resistance can be formed.
  • the polar groups contained in the fluorinated ether compound tend to form intramolecular interactions, and therefore the polar groups are less likely to participate in intermolecular interactions. Furthermore, when all of the multiple polar groups contained in the fluorinated ether compound are arranged with a sufficient distance between adjacent polar groups, all of the polar groups are likely to be involved in interactions with the protective layer, and sufficient interaction between the fluorinated ether compounds due to the polar groups is not obtained.
  • the inventors have confirmed that by using a lubricant containing the above-mentioned fluorine-containing ether compound, it is possible to form a lubricating layer that has good corrosion resistance and can suppress spin-off even when the thickness is reduced, and have arrived at the present invention.
  • the fluorine-containing ether compound, the lubricant for magnetic recording media, and the magnetic recording media of the present invention are described in detail below. Note that the present invention is not limited to the embodiments shown below.
  • the fluorine-containing ether compound of the present embodiment is represented by the following formula (1).
  • R 1 -CH 2 -R 2 -CH 2 -R 3 (1) (In formula (1), R2 is a perfluoropolyether chain. R1 and R3 are terminal groups having 1 to 4 polar groups and 1 to 50 carbon atoms. R1 and R3 may be the same or different. At least one of R1 and R3 is a terminal group represented by the following formula (2).) -O-X-CH(OH) -CH2OH (2) (In formula (2), X is a divalent organic group having 2 to 30 carbon atoms which may contain at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms. X contains at least one carbon atom which is not bonded to any of the polar groups and the ether oxygen atoms.)
  • the fluorine-containing ether compound of the present embodiment has a perfluoropolyether chain (hereinafter, sometimes referred to as PFPE chain) represented by R2 , in which an end group represented by R1 is bonded via a methylene group to one end of the skeleton, and an end group represented by R3 is bonded via a methylene group to the other end of the skeleton.
  • PFPE chain perfluoropolyether chain
  • R 1 and R 3 are terminal groups having 1 to 4 polar groups and 1 to 50 carbon atoms. At least one of R 1 and R 3 is a terminal group represented by the above formula (2).
  • R 1 and R 3 When one of R 1 and R 3 is a terminal group that does not fall under formula (2), the number of polar groups contained in the terminal group that does not fall under formula (2) among R 1 and R 3 is 1 or more. In addition, the number of polar groups contained in the terminal group represented by formula (2) is 2 or more. Therefore, when a lubricating layer is formed on a protective layer using a lubricant containing a fluorine-containing ether compound, a suitable interaction occurs between the lubricating layer and the protective layer.
  • the number of polar groups contained in R 1 and R 3 is preferably 2 or more.
  • the fluorine-containing ether compound has excellent adhesion to the protective layer, and further, the intermolecular interaction between the polar groups is suitably formed, and the lubricating layer that can suppress spin-off can be formed.
  • the number of polar groups contained in R 1 and R 3 is 4 or less. Therefore, in the lubricating layer containing the fluorine-containing ether compound, the polarity of the fluorine-containing ether compound is too high, so that the fluorine-containing ether compound aggregates and becomes a mass, and the smoothness of the lubricating layer is prevented from being lost.
  • the number of polar groups contained in R 1 and R 3 is preferably 3 or less.
  • the hydrophilicity of the fluorine-containing ether compound becomes too high, so that the water that causes corrosion is prevented from being taken into the magnetic recording medium, and the fluorine-containing ether compound can form a lubricating layer with high corrosion resistance.
  • the total number of polar groups of R 1 and R 3 in formula (1) is preferably 3 to 6, more preferably 4 to 6.
  • the total number of the polar groups is 3 or more, the interaction between the polar groups of R 1 and R 3 and the protective layer is effectively obtained.
  • the fluorine-containing ether compound can form a lubricating layer with high adhesion to the protective layer. Therefore, a lubricating layer with better spin-off resistance can be obtained.
  • the total number of the polar groups is 6 or less, the polarity of the fluorine-containing ether compound is too high, and water that causes corrosion can be prevented from being taken in. Therefore, a lubricating layer with better corrosion resistance can be formed.
  • the polar groups that R1 and R3 each have may be partially or entirely the same, or may be different.
  • the number of polar groups that R1 has and the number of polar groups that R3 has may be the same, or may be different.
  • the number of polar groups that R1 has and the number of polar groups that R3 has are preferably the same, because the covering state of the fluorine-containing ether compound with respect to the protective layer becomes more uniform, and a lubricating layer with better adhesion can be formed.
  • R 8 and R 9 may bond to each other to form a ring
  • R 10 and R 11 may bond to each other to form a ring.
  • R 8 , R 9 , R 10 and R 11 are preferably 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 term "polar group” does not include halogeno groups (--F, -Cl, -Br, etc.) or ether bonds (--O--).
  • R1 and R3 each independently comprise at least one polar group selected from the group consisting of hydroxyl group, cyano group, and group having amide bond.
  • hydroxyl group, cyano group, and group having amide bond are chemically stable, and the lubricating layer containing the fluorine-containing ether compound having these polar groups does not deteriorate over a long period of time.
  • hydroxyl group, cyano group, and group having amide bond are not too acidic, and do not corrode the substrate.
  • the polar groups of R1 and R3 each preferably contain at least one hydroxyl group. It is more preferable that the polar groups of R1 and R3 are all hydroxyl groups. When the polar groups of R1 and R3 are all hydroxyl groups, the coating state of the fluorine-containing ether compound on the protective layer becomes more uniform.
  • the number of carbon atoms of the terminal group represented by R 1 and R 3 is 1 to 50, preferably 3 to 20, and more preferably 4 to 15.
  • the number of carbon atoms of the terminal group represented by R 1 and R 3 is 1 or more, the hydrophobicity of the terminal group can be ensured, so that the lubricating layer can be prevented from attracting water, which causes corrosion, and the lubricating layer has good corrosion resistance.
  • the number of carbon atoms of the terminal group represented by R 1 and R 3 is 50 or less, the terminal group has a flexible structure, and the adhesion between the lubricating layer containing the fluorine-containing ether compound and the protective layer is good. As a result, a lubricating layer capable of suppressing spin-off is obtained.
  • At least one of R 1 and R 3 is a terminal group represented by the above formula (2).
  • the terminal group represented by formula (2) has an oxygen atom (ether oxygen atom) bonded to a methylene group (-CH 2 -) bonded to R 2.
  • the oxygen atom arranged at the end of the terminal group represented by formula (2) forms an ether bond (-O-) with the atoms bonded to both sides of it.
  • This ether bond imparts appropriate flexibility to the fluorine-containing ether compound represented by formula (1) and increases the affinity between the polar group of the terminal group represented by formula (2) and the protective layer.
  • the fluorine-containing ether compound represented by formula (1) can form a lubricating layer that has excellent adhesion to the protective layer.
  • the terminal group represented by formula (2) has a 1,2-diol structure (-CH(OH)-CH 2 OH) at its terminal. Therefore, a lubricating layer containing the fluorine-containing ether compound represented by formula (1) has good corrosion resistance and can suppress spin-off.
  • the terminal group represented by formula (2) has a divalent organic group represented by X having 2 to 30 carbon atoms. Since the organic group represented by X has 2 or more carbon atoms, it is moderately rigid and can suppress intramolecular interactions while at the same time obtaining sufficient hydrophobicity. Furthermore, since the number of carbon atoms is 30 or less, it is possible to prevent the terminal group represented by formula (2) from becoming too bulky, which would impede the movement of the polar group and inhibit the interaction with the protective layer.
  • the number of carbon atoms in the organic group represented by X is preferably 2 to 15, and more preferably 3 to 10.
  • the organic group represented by X contains at least one carbon atom that is not bonded to either polar group or ether oxygen atom.
  • Examples of the carbon atom that is not bonded to either polar group or ether oxygen atom include carbon atoms of methylene group, methine group, or fluorinated groups thereof that are not bonded to either polar group or ether oxygen atom.
  • fluoro group is not included in the polar group.
  • the organic group represented by X has a polar group containing a carbon atom (for example, a carboxy group, a formyl group, a carbonyl group, a cyano group, or a group having an amide bond)
  • the carbon atom contained in the polar group is not included in the "carbon atom that is not bonded to either a polar group or an ether oxygen atom.”
  • the number of carbon atoms that are not bonded to either polar groups or ether oxygen atoms may be 1 or more, and may be, for example, 1 to 6, or may be 1 to 4.
  • the hydrophobicity of the lubricating layer containing the fluorine-containing ether compound is good.
  • the ratio of the number of carbon atoms to the number of polar groups is appropriate, the polarity of the molecule is appropriate, and the ratio of the number of carbon atoms to the number of ether oxygen atoms is appropriate, resulting in a fluorine-containing ether compound with appropriate molecular flexibility.
  • the compound contains multiple carbon atoms that are not bonded to either polar groups or ether oxygen atoms, the carbon atoms that are not bonded to either polar groups or ether oxygen atoms may be bonded to each other.
  • the fluorine-containing ether compound molecule becomes more rigid, the intramolecular interaction between the polar groups is suppressed, and the polar groups are more likely to be involved in the intermolecular interaction between the fluorine-containing ether compounds.
  • the organic group represented by X may contain one or two polar groups.
  • the adhesion of the fluorine-containing ether compound represented by formula (1) to the protective layer is improved, and it is easy to form a lubricating layer that provides a sufficient coating state even if the thickness is thin.
  • the organic group represented by X contains a polar group, the number of polar groups is preferably one. In this case, it is possible to further suppress the fluorine-containing ether compound represented by formula (1) from being too hydrophilic and inducing water that causes corrosion.
  • examples of the polar group include those exemplified as the polar groups contained in R1 and R3 , and a polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond is more preferable.
  • the organic group represented by X in formula (2) may contain 1 to 3 ether oxygen atoms.
  • the ether oxygen atoms impart appropriate flexibility to the fluorinated ether compound represented by formula (1) and increase the affinity between the polar group and the protective layer.
  • the number of ether oxygen atoms is preferably 1 or 2. In this case, it is possible to further prevent the fluorinated ether compound represented by formula (1) from becoming too flexible and causing intramolecular interactions.
  • the organic group represented by X in formula (2) may be partially fluorinated.
  • the hydrophilicity of the organic group represented by X in formula (2) is reduced compared to when the organic group is not fluorinated.
  • the fluorine-containing ether compound can suppress the induction of water that causes corrosion and can form a lubricating layer with good corrosion resistance.
  • the organic group represented by X is preferably a non-cyclic organic group.
  • the organic group represented by X is acyclic, it is possible to prevent the organic group from becoming too bulky and hindering the movement of the polar group and inhibiting the interaction with the protective layer, compared to when X has a cyclic structure.
  • the non-cyclic organic group may be linear or branched.
  • the organic group represented by X does not contain an unsaturated carbon-carbon bond.
  • the orientation of the molecules is restricted, the movement of the polar groups is hindered, and the inhibition of interaction with the protective layer can be suppressed, compared to when X contains an unsaturated carbon-carbon bond.
  • the terminal group represented by formula (2) is preferably any one of the following formulas (2-1) to (2-7).
  • the terminal group represented by formula (2-1) is an organic group represented by X in formula (2) that is -CH 2 -CH(OH)-(CH 2 ) a -O-(CH 2 ) b -CH 2 -, where a is an integer of 1 to 8, and b is an integer of 1 to 7.
  • the terminal group represented by formula (2-1) has a structure in which a glycerin structure (-O-CH 2 -CH(OH)-CH 2 OH) is carbonized with b methylene groups at the terminal portion. Since the structure in which the glycerin structure is carbonized has a moderate rigidity, the terminal group represented by formula (2-1) can be suppressed from forming an intramolecular interaction. In addition, the ether bond in the structure in which the glycerin structure is carbonized imparts a moderate mobility to the terminal group represented by formula (2-1), so that when one of the two hydroxyl groups at the terminal portion interacts with the protective layer, the other hydroxyl group is more likely to be involved in the intermolecular interaction between the fluorine-containing ether compounds.
  • the polar group in the fluorine-containing ether compound represented by formula (1) can more easily form an intermolecular interaction.
  • the lubricating layer containing the fluorine-containing ether compound represented by formula (1) is less likely to scatter the fluorine-containing ether compound due to the rotation of the magnetic recording medium, and is more excellent in spin-off resistance.
  • a in formula (2-1) is 1 or more, the terminal group represented by formula (2-1) has sufficient hydrophobicity.
  • a is 8 or less, the number of a is not too large, so that the terminal group represented by formula (2-1) does not become too bulky, and the movement of the hydroxyl group in the terminal group represented by formula (2-1) is prevented from being hindered, thereby preventing the interaction with the protective layer from being hindered.
  • a is preferably 1 to 6, and more preferably 1 to 4.
  • b in formula (2-1) is 1 or more, the terminal group represented by formula (2-1) has sufficient hydrophobicity. In addition, because b is 7 or less, the terminal group represented by formula (2-1) does not become too bulky due to the number of b being too large, and it is possible to suppress the movement of the hydroxyl group in the terminal group represented by formula (2-1) being hindered and the inhibition of interaction with the protective layer.
  • b is preferably 1 to 5, and more preferably 1 to 3.
  • the sum of a and b in formula (2-1) is preferably 9 or less.
  • the terminal group represented by formula (2-1) does not become too bulky, and the movement of the hydroxyl group in the terminal group represented by formula (2-1) is hindered, which further suppresses the inhibition of the interaction with the protective layer.
  • the sum of a and b is more preferably 6 or less, and even more preferably 4 or less.
  • the terminal group represented by formula (2-2) is an organic group represented by X in formula (2) that is --CH.sub.2-- CH(OH)-- CH.sub.2 --( CH.sub.2 ) c --O-- CH.sub.2-- , where c is an integer of 1 to 7.
  • the terminal group represented by formula (2-2) has a glycerin structure (-O-CH 2 -CH(OH)-CH 2 OH) at the terminal portion. Since the glycerin structure has high mobility, when one of the two hydroxyl groups at the terminal portion interacts with the protective layer, the other hydroxyl group is likely to interact intermolecularly with a polar group in another fluorine-containing ether compound. Therefore, the polar group in the fluorine-containing ether compound represented by formula (1) can more easily form an intermolecular interaction. As a result, a lubricant containing the fluorine-containing ether compound represented by formula (1) is less likely to scatter the fluorine-containing ether compound as the magnetic recording medium rotates, and has even better spin-off resistance.
  • c in formula (2-2) is 1 or more, the terminal group represented by formula (2-2) has sufficient hydrophobicity. Furthermore, since c is 7 or less, the terminal group represented by formula (2-2) does not become too bulky due to the number of c being too large, and it is possible to suppress the movement of the hydroxyl group in the terminal group represented by formula (2-2) being hindered and the inhibition of interaction with the protective layer.
  • c is preferably 1 to 5, and more preferably 1 to 3.
  • the terminal group represented by formula (2-3) is an organic group represented by X in formula (2) which is --CH 2 --CH(OH)--(CH 2 ) d --, where d is an integer of 1 to 6.
  • the terminal group represented by formula (2-3) does not contain an ether oxygen atom, which is a hydrophilic site, in X. For this reason, the terminal group represented by formula (2-3) has a low affinity for water. As a result, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) is less likely to absorb water, which causes corrosion, and has better corrosion resistance.
  • the terminal group represented by formula (2-3) does not contain an ether oxygen atom in X in formula (2), and d is 1 or more, so that it is moderately rigid. As a result, intramolecular interactions between polar groups are more effectively suppressed, and intermolecular interactions are more easily formed, making it possible to form a lubricating layer with even better spin-off resistance.
  • d is 6 or less, the terminal group represented by formula (2-3) does not become too bulky due to the number d being too large, and the movement of the hydroxyl group in the terminal group represented by formula (2-3) is hindered, thereby preventing the interaction with the protective layer from being hindered.
  • d is preferably 1 to 4, and more preferably 2 to 4.
  • the organic group represented by X in formula (2) is -CH2- CH(OH) -CH2 -O- CH2- ( CRaRb ) e - CH2 -O- CH2- , where e represents an integer of 1 to 6.
  • e instances of R a and R b each independently represent a hydrogen atom or a methyl group.
  • Each of the e --CR a R b -- groups in the terminal group represented by formula (2-4) may be any of --CH 2 --, --CH(CH 3 )--, and --C(CH 3 ) 2 --.
  • the terminal group represented by formula (2-4) when the organic group represented by X in formula (2) has a linear structure, that is, when R a and R b are hydrogen atoms, the terminal group is not too bulky compared to when X has a branch. Therefore, it is possible to suppress the movement of the hydroxyl group from being hindered and the interaction with the protective layer being inhibited. As a result, when one of the two hydroxyl groups forming the terminal 1,2-diol structure interacts with the protective layer, the other hydroxyl group can more easily form an intermolecular interaction with a polar group in another fluorine-containing ether compound. This makes it more difficult for the fluorine-containing ether compound to scatter when the magnetic recording medium rotates, and the lubricant containing the fluorine-containing ether compound represented by formula (1) has excellent spin-off resistance.
  • the organic group represented by X in formula (2) contains a branched structure, i.e., -CH(CH 3 )- and/or -C(CH 3 ) 2 -
  • X becomes appropriately rigid and can effectively suppress intramolecular interactions between hydroxyl groups of the terminal groups. Therefore, the polar groups in the fluorine-containing ether compound represented by formula (1) can more easily form intermolecular interactions.
  • the lubricant containing the fluorine-containing ether compound represented by formula (1) is less likely to scatter due to the rotation of the magnetic recording medium, and has even better spin-off resistance.
  • e in formula (2-4) is 1 or more, the terminal group represented by formula (2-4) has sufficient hydrophobicity. Also, since e is 6 or less, the terminal group represented by formula (2-4) does not become too bulky, and the movement of the hydroxyl group is prevented from being hindered, thereby preventing the interaction with the protective layer from being inhibited.
  • e is preferably 1 to 4, and more preferably 1 to 2.
  • the terminal group represented by formula (2-5) is an organic group represented by X in formula (2) that is —CH 2 —CH(OH)—CH 2 —O—CH 2 —(CF 2 ) f —CH 2 —O—CH 2 —, where f is an integer of 1 to 6.
  • the terminal group represented by formula (2-5) contains a linear perfluoroalkylene chain having 1 to 6 carbon atoms, which reduces the affinity with water.
  • the saturated hydrocarbon group containing the perfluoroalkylene chain (-CH 2 -(CF 2 ) f -CH 2 - in formula (2-5)) reduces the polarity of the entire molecule and improves the hydrophobicity. This reduces the affinity between the fluorine-containing ether compound and water, which causes corrosion.
  • the lubricating layer containing the fluorine-containing ether compound represented by formula (1) is inhibited from taking in water, which causes corrosion, and has even better corrosion resistance.
  • f in formula (2-5) is 1 or more, the terminal group represented by formula (2-5) becomes appropriately rigid, and intramolecular interactions can be suppressed. Furthermore, since f is 6 or less, the terminal group represented by formula (2-5) does not become too bulky, and the movement of the hydroxyl group is prevented from being hindered, and the interaction with the protective layer is prevented from being inhibited.
  • f is preferably 1 to 4, and more preferably 2 to 4.
  • the terminal group represented by formula (2-6) is an organic group represented by X in formula (2) that is --(CH 2 ) g --CH 2 --, where g is an integer of 1 to 6.
  • the terminal group represented by formula (2-6) does not contain a polar group or an ether oxygen atom, which are hydrophilic sites, in X. For this reason, the terminal group represented by formula (2-6) has a low affinity for water. Therefore, a lubricating layer containing a fluorine-containing ether compound represented by formula (1) is less likely to absorb water, which causes corrosion, and has better corrosion resistance.
  • formula (2-6) Since g in formula (2-6) is 1 or more, formula (2-6) becomes moderately rigid, and the hydroxyl groups of the 1,2-diol structure are less likely to form intramolecular interactions. Furthermore, since g in formula (2-6) is 6 or less, the terminal group represented by formula (2-6) does not become too bulky, and the movement of the hydroxyl groups is prevented from being hindered, thereby preventing the interaction with the protective layer from being hindered.
  • g is preferably 1 to 5, and more preferably 1 to 3.
  • the terminal group represented by formula (2-7) has the organic group represented by X in formula (2) being -(CH 2 ) g2 -CH 2 -CH(OH)-CH 2 -O-CH 2 -, where g2 represents an integer of 1 to 6.
  • the terminal group represented by formula (2-7) has a glycerin structure (-O-CH 2 -CH(OH)-CH 2 OH) at the terminal portion. Since the glycerin structure has high mobility, when one of the two hydroxyl groups at the terminal portion interacts with the protective layer, the other hydroxyl group is likely to interact intermolecularly with a polar group in another fluorine-containing ether compound.
  • the polar group in the fluorine-containing ether compound represented by formula (1) can more easily form an intermolecular interaction.
  • a lubricant containing the fluorine-containing ether compound represented by formula (1) is less likely to scatter the fluorine-containing ether compound as the magnetic recording medium rotates, and has even better spin-off resistance.
  • formula (2-7) Since g2 in formula (2-7) is 1 or more, formula (2-7) becomes moderately rigid, and the hydroxyl groups of the 1,2-diol structure are less likely to form intramolecular interactions. In addition, since g2 in formula (2-7) is 6 or less, the terminal group represented by formula (2-7) does not become too bulky, and the movement of the hydroxyl groups is prevented from being hindered, which prevents the interaction with the protective layer from being hindered. g2 is preferably 1 to 5, and more preferably 1 to 3.
  • terminal groups represented by formulas (2-1) to (2-7) the terminal groups represented by formulas (2-3), (2-5), and (2-6) have better corrosion resistance.
  • the terminal groups represented by formulas (2-1) to (2-7) have better spin-off resistance when the sum of a and b in formula (2-1) is 4 or less, c in formula (2-2) is 3 or less, e in formula (2-4) is 2 or less, and g2 in formula (2-7) is 3 or less.
  • R 1 and R 3 may be the same or different. It is preferable that R 1 and R 3 are the same. In this case, the fluorine-containing ether compound can be produced easily and efficiently.
  • “R 1 and R 3 are the same” means that the atoms contained in R 1 and the atoms contained in R 3 are arranged symmetrically with respect to -CH 2 -R 2 -CH 2 -.
  • R 1 and R 3 may each independently be an end group represented by formula (2), or one of R 1 and R 3 may be an end group represented by formula (2) and the other may be an end group not corresponding to formula (2).
  • the end group not corresponding to formula (2) may be an end group having 1 to 4 polar groups and 1 to 50 carbon atoms, as described above.
  • R1 and R3 are end groups represented by formula (2) and the other is an end group not corresponding to formula (2)
  • the end group not corresponding to formula (2) is preferably represented by the following formula (3).
  • l represents an integer of 1 to 3.
  • l's m each independently represents an integer of 1 to 6.
  • l's n each independently represents an integer of 1 to 6.
  • B represents an alkyl group which may have only one polar group, an organic group containing a carbon-carbon unsaturated bond, or a hydrogen atom.
  • the terminal group represented by formula (3) has an oxygen atom (ether oxygen atom) bonded to a methylene group (-CH 2 -) bonded to R 2.
  • the oxygen atom located at the end of the terminal group represented by formula (3) forms an ether bond (-O-) with the atoms bonded to both sides of it.
  • This ether bond imparts appropriate flexibility to the fluorine-containing ether compound represented by formula (1) and increases the affinity between the polar group of the terminal group represented by formula (3) and the protective layer.
  • the fluorine-containing ether compound represented by formula (1) can form a lubricating layer that has excellent adhesion to the protective layer.
  • l is an integer of 1 to 3, preferably an integer of 1 to 2, and more preferably 1. If l in formula (3) is 3 or less, the number of hydroxyl groups in the terminal groups represented by formula (3) is too large, which can prevent water, which causes corrosion, from being attracted to the lubricating layer, and a lubricating layer with good corrosion resistance can be obtained.
  • l m's each independently represent an integer from 1 to 6.
  • l n's each independently represent an integer from 1 to 6.
  • one repeating unit (-(CH 2 ) m -CH(OH)-(CH 2 ) n -O-) in formula (3) at least one of m and n is 1. In this case, it is possible to suppress a decrease in the mobility of the hydroxyl group in the repeating unit due to an excessive number of carbon atoms in the alkylene group between the carbon atom to which the hydroxyl group is bonded and the ether oxygen atom.
  • B represents an alkyl group that may have only one polar group, an organic group that contains a carbon-carbon unsaturated bond, or a hydrogen atom.
  • B in formula (3) is an alkyl group that does not have a polar group
  • examples of B include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.
  • the polar group is preferably one of the preferred examples of the polar group contained in R 1 and R 3.
  • a polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond is more preferred.
  • examples of B include 2-hydroxyethyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxyhexyl group, 2-aminoethyl group, 3-aminopropyl group, 1-carboxymethyl group, 2-carboxyethyl group, 3-carboxypropyl group, 1-carbonylmethyl group, 2-carbonylethyl group, 3-carbonylpropyl group, 1-acetylmethyl group, 2-acetylethyl group, 3-acetylpropyl group, 2-sulfoethyl group, 3-sulfopropyl group, 1-cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, 2-acetamidoethyl group, 3-acetamidopropyl group, 4-acetamidobutyl group, 1-carboxamidomethyl group, 2-carboxamidomethyl group, 2-carboxyl group, 4-hydroxybut
  • any of the following is preferred: 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 1-cyanomethyl, 2-cyanoethyl, 3-cyanopropyl, 2-acetamidoethyl, 1-carboxamidomethyl, 2-carboxamidoethyl, and 3-carboxamidopropyl groups, and any of the following is more preferred: 2-hydroxyethyl, 3-hydroxypropyl, 2-cyanoethyl, 3-cyanopropyl, 2-acetamidoethyl, and 1-carboxamidomethyl groups.
  • examples of B include an organic group containing at least one selected from an aromatic hydrocarbon, an unsaturated heterocycle, an alkenyl group, and an alkynyl group.
  • examples of B include a phenyl group, a methoxyphenyl group, a fluorinated phenyl group, an acetamidophenyl group, a carboxamidophenyl group, a cyanophenyl group, a naphthyl group, a phenethyl group, a methoxyphenethyl group, a fluorinated phenethyl group, a benzyl group, a methoxybenzyl group, a naphthylmethyl group, a methoxynaphthyl group, a pyrrolyl group, a pyrazolyl group, a methylpyrazolylmethyl group, an imidazolyl group, a furyl group, a furfuryl group, an oxazolyl group, an isoxazolyl group, a thienyl group,
  • alkyl group examples include ethyl, isothiazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, indolinyl, benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzopyrazolyl, benzoisoxazolyl, benzoisothiazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, phthalazinyl, cinnolinyl, vinyl, allyl, butenyl, propynyl, propargyl, butynyl, methylbutynyl, pentynyl, methylpentynyl, and hexynyl groups.
  • any of the following is preferred: phenyl, methoxyphenyl, acetamidophenyl, carboxamidophenyl, cyanophenyl, naphthyl, phenethyl, methoxyphenethyl, fluorinated phenethyl, thienylethyl, allyl, butenyl, and propargyl, and more preferably any of the following: phenyl, methoxyphenyl, carboxamidophenyl, allyl, and butenyl.
  • the terminal group represented by formula (3) has sufficient hydrophobicity and is not too bulky, so that the movement of the hydroxyl group in formula (3) is hindered, and the interaction with the protective layer is prevented from being inhibited.
  • B in formula (3) is a hydrogen atom
  • B forms a hydroxyl group together with the oxygen atom in formula (3).
  • the terminal group represented by formula (3) is more preferably represented by any one of the following formulas (3-1) to (3-3).
  • p represents an integer of 0 to 3.
  • q represents an integer of 0 to 2.
  • r represents an integer of 0 to 5. The total value of p and r is 1 to 5.
  • D represents a polar group, a vinyl group, an ethynyl group, or an aryl group which may have a substituent.
  • s represents an integer of 0 to 2.
  • t represents an integer of 1 to 5.
  • u represents an integer of 1 to 3.
  • Each of the five E's independently represents a polar group, an alkoxy group having 1 to 8 carbon atoms, a halogeno group, or a hydrogen atom. However, when the five E's include a polar group, the number of polar groups among the five E's is 1.
  • each polar group contained in the terminal group is bonded to a different carbon atom.
  • the carbon atoms to which the polar groups are bonded are bonded to each other via a linking group that includes a carbon atom to which no polar group is bonded.
  • the terminal groups represented by formulas (3-1) to (3-3) can be oriented in such a way that both the terminal polar group and the hydroxyl group adjacent to the terminal polar group can adhere to the protective layer, due to the linking group that includes a carbon atom to which no polar group is bonded. Therefore, a lubricating layer that has a strong interaction with the protective layer can be formed.
  • the polar groups in the terminal groups are less likely to aggregate with each other and are more likely to interact with the protective layer than in terminal groups in which the carbon atoms to which the polar groups are bonded are directly bonded. For this reason, the terminal portions of the terminal groups represented by formulas (3-1) to (3-3) in the fluorinated ether compound are less likely to float up, and the adhesion to the protective layer is less likely to decrease.
  • the linking group between the carbon atom to which D is bonded and the carbon atom to which the hydroxyl group adjacent to D at the terminal is bonded contains an ether oxygen atom.
  • the linking group has a linear structure consisting of 2 to 7 atoms, including a carbon atom to which no polar group is bonded.
  • the terminal group represented by formula (3-1) has a linear structure in which the linking group is composed of two or more atoms including a carbon atom to which no polar group is bonded. Therefore, the distance between D and the hydroxyl group adjacent to D is appropriate. Therefore, it is possible to suppress the interaction between D and the hydroxyl group adjacent to D within the molecule, and the polar group can be efficiently adhered to the protective layer. Furthermore, since the terminal group represented by formula (3-1) has the above structure, a fluorine-containing ether compound having good hydrophobicity can be obtained even if it contains an ether oxygen atom. In addition, the molecular mobility is appropriate, intramolecular aggregation is unlikely to occur, and the compound has excellent adhesion to the protective layer.
  • the terminal group represented by formula (3-1) is a linear structure in which the linking group contains an ether oxygen atom and is composed of 7 or less atoms including a carbon atom to which no polar group is bonded. Therefore, the adhesion between the lubricating layer containing the fluorine-containing ether compound and the protective layer is not impaired due to the linking group being too hydrophobic.
  • a fluorine-containing ether compound having a terminal group represented by formula (3-1) can form a lubricating layer that has excellent adhesion to a protective layer, exhibits high corrosion resistance, and can suppress spin-off.
  • the terminal group represented by formula (3-1) has a linking group between the carbon atom to which D is bonded and the carbon atom to which the hydroxyl group adjacent to D located at the terminal is bonded.
  • the carbon atom contained in the linking group prevents the intramolecular interaction between adjacent polar groups from occurring in preference to the interaction between the polar groups and the protective layer. As a result, the carbon atom contained in the linking group improves the adhesion between the polar group in formula (3-1) and the protective layer.
  • the flexibility of the terminal group represented by formula (3-1) decreases, and it may become difficult to uniformly cover the entire surface of the protective layer.
  • the total value of p and r is 5 or less, so the alkylene chain in the main chain portion of formula (3-1) is not too long. Therefore, the long rigid alkylene chain reduces the flexibility of the terminal portion, weakening the interaction with the protective layer and preventing the terminal portion from lifting up.
  • p is an integer from 0 to 3, preferably 0 or 1, and more preferably 0.
  • r is an integer from 0 to 5, preferably 1 or 2, and more preferably 1.
  • D in formula (3-1) represents a polar group, a vinyl group, an ethynyl group, or an aryl group which may have a substituent.
  • D is a polar group
  • D is preferably one of the preferred examples of the polar group contained in R 1 and R 3.
  • D is more preferable that D is a polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond.
  • D is an aryl group which may have a substituent
  • an aryl group which may have a substituent and is contained in the organic group which can be used when B in the above formula (3) is an organic group containing a carbon-carbon unsaturated bond can be used.
  • q represents an integer of 0 to 2.
  • the number of polar groups in formula (3-1) is q+2 when D is a polar group, and q+1 when D is a vinyl group or an ethynyl group.
  • the number of polar groups contained in R 1 and R 3 is preferably 2 or 3, respectively. Therefore, q in formula (3-1) is preferably 0 or 1 when D is a polar group, and is preferably 1 or 2 when D is a vinyl group or an ethynyl group.
  • D is an aryl group which may have a substituent, it is preferable to select q so that the number of polar groups in formula (3-1) is 2 or 3.
  • 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.
  • intramolecular interactions are small and intramolecular aggregation is unlikely to occur, resulting in excellent adhesion to the protective layer.
  • the terminal group represented by formula (3-2) has a linear structure in which the linking group is made up of 1 to 5 atoms including a carbon atom not bonded to a hydroxyl group. Because the linking group is made up of a linear structure made up of one or more atoms including a carbon atom not bonded to a hydroxyl group, the distance between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group is appropriate. Therefore, intramolecular aggregation is unlikely to occur, and a fluorine-containing ether compound having good hydrophobicity can be obtained.
  • the terminal group represented by formula (3-2) is a linear structure in which the linking group does not contain an oxygen atom and is composed of five or less atoms including a carbon atom to which no hydroxyl group is bonded. Therefore, the linking group is not so hydrophobic that it interferes with adhesion to the protective layer, and the linking group is not so bulky that it interferes with the movement of the hydroxyl group.
  • t is an integer of 1 to 5.
  • the flexibility of the terminal group represented by formula (3-2) decreases, and it may become difficult to uniformly cover the entire surface of the protective layer.
  • t is 5 or less, so that the alkylene chain in the main chain portion of formula (3-2) is not too long. Therefore, it is possible to prevent the flexibility of the terminal portion from decreasing due to the long rigid alkylene chain, and the interaction between the terminal hydroxyl group and the protective layer from decreasing.
  • t is preferably 1 or 2, and more preferably 1.
  • the fluorine-containing ether compound having an end group represented by formula (3-2) can form a lubricating layer that has excellent adhesion to the protective layer, high corrosion resistance, and can suppress spin-off, because the linking group in formula (3-2) does not contain an oxygen atom and has a linear structure consisting of 1 to 5 atoms including a carbon atom that is not bonded to a hydroxyl group.
  • s represents an integer of 0 to 2.
  • the number of polar groups in formula (3-2) is s+2, and as described above, the number of polar groups contained in R1 and R3 is preferably 2 or 3, respectively. Therefore, in formula (3-2), s is preferably 0 or 1.
  • the five E's each independently represent a polar group, an alkoxy group having 1 to 8 carbon atoms, a halogeno group, or a hydrogen atom. If the five E's include a polar group, the number of polar groups among the five E's is one.
  • the linking group between the carbon atom to which the polar group represented by E is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group represented by E is bonded contains an oxygen atom forming an ether bond.
  • the linking group has a structure consisting of 3 to 5 atoms, including a carbon atom to which no polar group is bonded.
  • the number of atoms in the linking group refers to the number of atoms in the shortest distance between the carbon atom to which the polar group contained in E is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group contained in E is bonded.
  • the linking group contains an oxygen atom forming an ether bond, and is a structure consisting of three or more atoms including a carbon atom to which no polar group is bonded. Therefore, the distance between the polar group represented by E and the hydroxyl group adjacent to the polar group represented by E is appropriate.
  • the benzene ring is rigid, making it difficult for it to rotate freely. Therefore, it is possible to suppress interaction between the polar group represented by E, which is a substituent bonded to the benzene ring, and the hydroxyl group adjacent to the polar group represented by E.
  • u represents an integer of 1 to 3.
  • the linking group between the carbon atoms to which adjacent hydroxyl groups are bonded which is included in -(CH 2 CH(OH)CH 2 O) u -, contains an oxygen atom forming an ether bond, and has a linear structure consisting of three atoms including a carbon atom to which no hydroxyl group is bonded. Since the linking group has a linear structure consisting of three atoms including a carbon atom to which no hydroxyl group is bonded, the distance between adjacent hydroxyl groups is appropriate. Therefore, it is possible to suppress interaction between hydroxyl groups within the molecule.
  • a lubricating layer containing a fluorine-containing ether compound having a terminal group represented by formula (3-3) has excellent adhesion to the protective layer and is highly effective in suppressing spin-off.
  • a lubricating layer containing a fluorine-containing ether compound having a terminal group represented by formula (3-3) can further suppress the induction of water, which causes corrosion, and has higher corrosion resistance.
  • E when E is a polar group, E is preferably one of the preferred examples of the polar group contained in R 1 and R 3.
  • the polar group is a cyano group, an acetamide group or a carboxamide group
  • the fluorine-containing ether compound can form a lubricating layer with a stronger interaction with the protective layer.
  • the fluorine-containing ether compound having these groups hardly has an effect of corroding the substrate.
  • E is not a polar group, it is preferable that each of them is independently a methoxy group, a fluoro group or a hydrogen atom.
  • the number of polar groups in formula (3-3) is u+1 when the five E's contain polar groups, and is u when the five E's do not contain polar groups.
  • the number of polar groups contained in R 1 and R 3 is preferably 2 or 3, respectively. Therefore, u in formula (3-3) is preferably 1 or 2 when the five E's contain polar groups, and is preferably 2 or 3 when the five E's do not contain polar groups.
  • the five E's in formula (3-3) include polar groups, some or all of the four E's other than the polar groups may be the same, or they may be different from each other.
  • the five E's include polar groups it is preferable that the four E's other than the polar groups are all the same.
  • the five E's do not include polar groups some or all of the five E's may be the same, or they may be different from each other.
  • the polar groups may be located at any of the five E's.
  • R2 is a perfluoropolyether chain.
  • the PFPE chain represented by R2 covers the surface of the protective layer and imparts lubricity to the lubricating layer, thereby reducing the frictional force between the magnetic head and the protective layer.
  • the PFPE chain represented by R2 is appropriately selected according to the performance required for the lubricant containing the fluorine-containing ether compound.
  • the PFPE chain represented by R2 may be a polymer or copolymer of perfluoroalkylene oxide.
  • perfluoroalkylene oxide include perfluoromethylene oxide, perfluoroethylene oxide, perfluoro-n-propylene oxide, perfluoroisopropylene oxide, and perfluorobutylene oxide.
  • R2 in formula (1) is preferably a PFPE chain represented by the following formula (4) derived from a polymer or copolymer of perfluoroalkylene oxide.
  • formula (4) derived from a polymer or copolymer of perfluoroalkylene oxide.
  • w1 and w6 represent an average value representing the number of CF2 and each independently represents 1 to 3. There is no particular restriction on the arrangement order of the repeating units (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).)
  • w2, w3, w4, and w5 each independently represent an average degree of polymerization of 0 to 20, preferably 0 to 15, and more preferably 0 to 10.
  • w1 and w6 are average values indicating the number of CF2 , and each independently represents 1 to 3.
  • w1 and w6 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), etc.
  • (CF 2 O), (CF 2 CF 2 O), (CF 2 CF 2 CF 2 O), and (CF 2 CF 2 CF 2 O) are repeating units. There is no particular restriction on the arrangement order of the repeating units in formula (4). There is also no particular restriction on the number of types of repeating units in formula (4).
  • R 2 in formula (1) is preferably any one selected from the PFPE chains represented by the following formulas (4-1) to (4-4).
  • -CF 2 -(OCF 2 CF 2 ) h -(OCF 2 ) i -OCF 2 - (4-1) (In formula (4-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20.)
  • j represents the average degree of polymerization and is 1 to 15.
  • k represents the average degree of polymerization and is 1 to 10.)
  • the fluorine-containing ether compound provides a lubricating layer having good lubricity.
  • the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) to the number of carbon atoms in the PFPE chain is appropriate. Therefore, the fluorine-containing ether compound has a moderate hardness. Therefore, the fluorine-containing ether compound applied on the protective layer is less likely to aggregate on the protective layer, and a lubricating layer with a thinner thickness can be formed with a sufficient coverage.
  • the lubricating layer containing the fluorine-containing ether compound in which R 2 is any one selected from the PFPE chains represented by formulas (4-1) to (4-4) is denser and can further suppress spin-off, which is preferable.
  • 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) may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF 2 CF 2 ) and (OCF 2 ).
  • h which indicates the average degree of polymerization
  • i which is 0 to 20
  • h and i which indicate the average degree of polymerization
  • j is 15 or less
  • k is 10 or less, so the viscosity of the fluorine-containing ether compound is not too high, and the lubricant containing the fluorine-containing ether compound is easy to apply, which is preferable.
  • h, i, j, and k which indicate the average degree of polymerization, are preferably 1 to 10, more preferably 1.5 to 8, and even more preferably 2 to 7, so that the fluorine-containing ether compound can easily wet and spread on the protective layer and easily provide a lubricating layer with a uniform thickness.
  • the arrangement order of the repeating units (CF 2 CF 2 CF 2 O) and (CF 2 CF 2 O) is not particularly limited.
  • the number w8 of (CF 2 CF 2 O) and the number w9 of (CF 2 CF 2 O) showing the average degree of polymerization may be the same or different.
  • Formula (4-4) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF 2 CF 2 CF 2 O) and (CF 2 CF 2 O ).
  • w8 and w9 each representing the average degree of polymerization independently represent 1 to 20, preferably 1 to 15, and more preferably 1 to 10.
  • w7 and w10 are average values indicating the number of CF2 , 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), etc.
  • the fluorine-containing ether compound represented by formula (1) is preferably any of the compounds represented by the following formulae (AA)-(AS), (BA)-(BH), and (CA)-(CK).
  • the compound represented by formula (1) is any of the compounds represented by the following formulae (AA)-(AS), (BA)-(BH), and (CA)-(CK)
  • the raw materials are easy to obtain, and even if the thickness is thin, a lubricating layer that has better corrosion resistance and can suppress spin-off can be formed.
  • Rf 1 , Rf 2 , and Rf 3 which represent PFPE chains, respectively have the following structures. That is, in the compounds represented by the following formulae (AA) to (AS), (BA) to (BF), (CA), (CB), and (CE), Rf 1 is a PFPE chain represented by the above formula (4-1). In the compounds represented by the following formulae (BG), (CC), and (CF) to (CK), Rf 2 is a PFPE chain represented by the above formula (4-2). In the compounds represented by the following formulae (BH) and (CD), Rf 3 is a PFPE chain represented by the above formula (4-3).
  • h and i in Rf1 , j in Rf2 , and k in Rf3 which represent the PFPE chain in the formulae (AA) to (AS), (BA) to (BH), and (CA) to (CK), are values indicating the average degree of polymerization, and therefore are not necessarily integers.
  • R 1 and R 3 in formula (1) are terminal groups represented by any one of the above formulae (2-1) to (2-6), and R 2 is a PFPE chain represented by the above formula (4-1).
  • R1 and R3 in formula (1) are an end group represented by the above formula (2-1), and the other is an end group represented by either of the above formulas (3-1) and (3-2), and R2 is a PFPE chain represented by the above formula (4-1).
  • one of R1 and R3 in formula (1) is an end group represented by the above formula (2-1), and the other is an end group represented by formula (3).
  • R2 is a PFPE chain represented by the above formula (4-1).
  • the end group represented by formula (3) does not correspond to any of the above formulae (3-1) to (3-3).
  • R1 and R3 in formula (1) are terminal groups represented by the above formula (2-1), and R2 is a PFPE chain represented by the above formula (4-2) or (4-3).
  • R1 and R3 in formula (1) are terminal groups represented by any one of the above formulas (2-1) to (2-7), and R2 is a PFPE chain represented by any one of the above formulas (4-1) to (4-3).
  • the number average molecular weight (Mn) of the fluorine-containing ether compound of this embodiment is preferably in the range of 500 to 10,000, and particularly preferably in the range of 1,000 to 5,000.
  • 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 1,000 or more.
  • the viscosity of the fluorine-containing ether compound becomes appropriate, and a lubricating layer with a thin film thickness can be easily formed by applying a lubricant containing this.
  • the number average molecular weight of the fluorine-containing ether compound is preferably 5,000 or less, since this results in 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 an AVANCEIII400 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 to obtain the number average molecular weight.
  • NMR nuclear magnetic resonance
  • the sample is diluted in a hexafluorobenzene/d-acetone (4/1 v/v) solvent and measured.
  • the reference of the 19 F-NMR chemical shift is the hexafluorobenzene peak at -164.7 ppm
  • the reference of the 1 H-NMR chemical shift is the acetone peak at 2.2 ppm.
  • the fluorine-containing ether compound of this embodiment is preferably fractionated by molecular weight using an appropriate method to make the molecular weight distribution (ratio of weight average molecular weight (Mw)/number average molecular weight (Mn)) 1.3 or less.
  • the method of molecular weight fractionation is not particularly limited, but for example, molecular weight fractionation by silica gel column chromatography, gel permeation chromatography (GPC), etc., molecular weight fractionation by supercritical extraction, etc. can be used.
  • the method for producing the fluorinated ether compound of the present embodiment is not particularly limited, and the compound can be produced by a conventionally known production method.
  • the fluorinated ether compound of the present embodiment can be produced, for example, by the production method shown below.
  • compounds represented by the following formulas (5-1) to (5-16) and the following formula (5-24) can be used.
  • compounds represented by the following formulas (5-25) to (5-27) can be used.
  • MOM in formulas (5-25) and (5-26) represents a methoxymethyl group.
  • Ts in formulas (5-25) to (5-27) represents a tosyl group.
  • the hydroxyl group of the epoxy compound (or a compound having a leaving group) may be protected with an appropriate protecting group before reacting with the fluorine-based compound.
  • An epoxy compound (e.g., an epoxy compound represented by formula (5-1)) can be produced by reacting an alcohol compound, which may be appropriately protected, with a halogen compound having an epoxy group, as shown in the following formula (6-1).
  • An epoxy compound (e.g., an epoxy compound represented by formula (5-5)) may be produced, for example, by reacting an alcohol compound having a vinyl group with a halogen compound having an alcohol that may be appropriately protected, as shown in formula (6-2) below, and then oxidizing the resulting compound with m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • An epoxy compound (e.g., an epoxy compound represented by formula (5-10)) may be produced by, for example, reacting a diol compound with a halogen compound having an alcohol, which may be appropriately protected, and a halogen compound having an epoxy group in sequence, as shown in formula (6-3) below.
  • the epoxy compound (or compound having a leaving group) may be purchased commercially.
  • a fluorine-based compound is prepared in which a hydroxymethyl group (-CH 2 OH) is arranged at each end of a perfluoropolyether chain corresponding to R 2 in formula (1).
  • the hydroxyl groups of the hydroxymethyl groups arranged at both ends of the fluorine-based compound are reacted with a halogen compound having a vinyl group at its end. This produces a compound having a vinyl group at both ends of a chain structure containing a perfluoropolyether chain.
  • a fluorine-based compound is prepared in which a hydroxymethyl group (—CH 2 OH) is located at each end of the perfluoropolyether chain corresponding to R 2 in formula (1).
  • the intermediate compound 1 is reacted with an epoxy compound having a group that becomes R3 in formula (1) (second reaction).
  • a compound having a leaving group may be used in place of the epoxy compound.
  • the epoxy compounds corresponding to the end group not corresponding to formula (2) may be, for example, epoxy compounds represented by the following formulas (5-17) to (5-23).
  • THP represents a tetrahydropyranyl group.
  • the lubricant for a magnetic recording medium of this embodiment contains a fluorine-containing ether compound represented by the above formula (1).
  • the lubricant of the present embodiment can be used by mixing, as necessary, known materials used as lubricant materials, so long as the properties resulting from the inclusion of the fluorinated ether compound represented by the above formula (1) are not impaired.
  • the known material to be mixed with the lubricant of this embodiment has a number average molecular weight of 1,000 to 10,000.
  • the content of the fluorine-containing ether compound represented by the above formula (1) in the lubricant of this embodiment is preferably 70 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more.
  • the lubricant of this embodiment contains a fluorine-containing ether compound represented by the above formula (1), and therefore can form a lubricating layer that has excellent corrosion resistance and can suppress spin-off.
  • 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 may be provided between the substrate and the magnetic layer, if necessary.
  • at least one of an adhesive 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 a magnetic recording medium of the present invention.
  • the magnetic recording medium 10 of this embodiment has a structure in which an adhesive layer 12, a soft magnetic layer 13, a first underlayer 14, a second underlayer 15, a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are sequentially provided on a substrate 11.
  • the substrate 11 may be, for example, a non-magnetic substrate in which a film made of NiP or a NiP alloy is formed on a base made of a metal or alloy material such as Al or an Al alloy. Furthermore, the substrate 11 may be a non-magnetic substrate made of a non-metallic material such as glass, ceramics, silicon, silicon carbide, carbon, or resin, or a non-magnetic substrate having a NiP or NiP alloy film formed on a base made of these non-metallic materials.
  • the adhesion layer 12 prevents the progress of corrosion of the substrate 11, which occurs when the substrate 11 and the soft magnetic layer 13 provided on the adhesion layer 12 are disposed in contact with each other.
  • the material of the adhesion layer 12 can be appropriately selected from, for example, Cr, a Cr alloy, Ti, a Ti alloy, CrTi, NiAl, an 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 preferably has a structure in which the intermediate layer made of a Ru film is sandwiched between two soft magnetic films, so that the soft magnetic films above and below the intermediate layer are anti-ferro-coupling (AFC).
  • AFC anti-ferro-coupling
  • the first and second soft magnetic films may be made of a material such as a CoZrTa alloy or a CoFe alloy. It is preferable to add any one of Zr, Ta, and Nb to the CoFe alloy used for the first and second soft magnetic films. This promotes the amorphization of the first and second soft magnetic films. As a result, it is possible to improve the orientation of the first underlayer (seed layer) and 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 the magnetic layer 16 that are provided thereon.
  • the first underlayer 14 may be, for example, a Cr layer, a Ta layer, a Ru layer, or a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, or a CrTi alloy layer.
  • the first underlayer 14 can be formed by, for example, a sputtering method.
  • the second underlayer 15 is a layer that controls good orientation of the magnetic layer 16.
  • the second underlayer 15 is preferably a layer made of Ru or a Ru alloy.
  • the second underlayer 15 may be a layer consisting of one layer, or may be composed of multiple layers. When the second underlayer 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 a different material.
  • the second underlayer 15 can be formed by, for example, a sputtering method.
  • the magnetic layer 16 is a magnetic film with an easy axis of magnetization oriented perpendicular or parallel to the substrate surface.
  • the magnetic layer 16 is a layer containing Co and Pt.
  • the magnetic layer 16 may be a layer containing an oxide, Cr, B, Cu, Ta, Zr, or the like to improve the SNR characteristics. Examples of oxides contained in the magnetic layer 16 include SiO2 , SiO, Cr2O3 , CoO, Ta2O3 , and TiO2 .
  • the magnetic layer 16 may be composed of a single layer, or may be composed of multiple magnetic layers made of materials with different compositions.
  • the first magnetic layer is preferably a granular structure made of a material containing Co, Cr, Pt, and further containing an oxide.
  • an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, etc. can be preferably used.
  • TiO 2 , Cr 2 O 3 , SiO 2, etc. can be particularly preferably used.
  • the first magnetic layer is preferably made of a composite oxide to which two or more kinds of oxides are added.
  • Cr 2 O 3 -SiO 2 , Cr 2 O 3 -TiO 2 , SiO 2 -TiO 2, etc. can be particularly preferably used.
  • the first magnetic layer may contain 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.
  • the second magnetic layer may be made of the same material as the first magnetic layer, and preferably has a granular structure.
  • the third magnetic layer preferably has a non-granular structure made of a material that contains Co, Cr, and Pt and does not contain oxides.
  • the third magnetic layer may contain, in addition to Co, Cr, and Pt, one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn.
  • the magnetic layer 16 When the magnetic layer 16 is formed of multiple magnetic layers, it is preferable to provide a non-magnetic layer between adjacent magnetic layers. When the magnetic layer 16 is composed of three layers, a first magnetic layer, a second magnetic layer, and a third magnetic layer, it is preferable to provide a non-magnetic layer between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.
  • the non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16 can be, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 represents one or more elements selected from Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Ti, V, and B), etc.
  • the non-magnetic layer provided between the adjacent magnetic layers of the magnetic layer 16 it is preferable to use an alloy material containing an oxide, a metal nitride , or a metal carbide.
  • an alloy material containing an oxide, a metal nitride , or a metal carbide Specifically, for example, SiO2 , Al2O3 , Ta2O5 , Cr2O3 , MgO, Y2O3 , TiO2 , etc. can be used as the oxide.
  • AlN , Si3N4 , TaN, CrN, etc. can be used as the metal nitride.
  • TaC, BC , SiC, etc. can be used as the metal carbide.
  • the nonmagnetic layer can be formed by, for example, a sputtering method.
  • the magnetic layer 16 is preferably a magnetic layer for perpendicular magnetic recording in which the axis of easy magnetization is oriented perpendicular to the substrate surface, but may also be a magnetic layer for in-plane magnetic recording.
  • the magnetic layer 16 may be formed by any conventionally known method such as vapor deposition, ion beam sputtering, magnetron sputtering, etc.
  • the magnetic layer 16 is usually formed by sputtering.
  • the protective layer 17 protects the magnetic layer 16.
  • the protective layer 17 may be composed of one layer or multiple layers.
  • a carbon-based protective layer can be preferably used as the protective layer 17, and an amorphous carbon protective layer is particularly preferred. If the protective layer 17 is a carbon-based protective layer, the interaction with the polar group (particularly the hydroxyl group) contained in the fluorine-containing ether compound in the lubricating layer 18 is further enhanced, which is preferable.
  • the adhesion between the carbon-based protective layer and the lubricating layer 18 can be controlled by making the carbon-based protective layer hydrogenated carbon and/or nitrogenated carbon and adjusting the hydrogen content and/or nitrogen content in the carbon-based protective layer.
  • the hydrogen content in the carbon-based protective layer is preferably 3 atomic % to 20 atomic % 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 entire carbon-based protective layer. It is preferable that the carbon-based protective layer be a compositionally graded layer, for example, in which nitrogen is contained on the lubricating layer 18 side of the protective layer 17, and hydrogen is contained on the magnetic layer 16 side of the protective layer 17. In this case, the adhesion between the magnetic layer 16 and the 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. If the thickness of the protective layer 17 is 1 nm or more, sufficient performance as the protective layer 17 can be obtained. If the thickness of the protective layer 17 is 7 nm or less, it is preferable from the viewpoint of making the protective layer 17 thinner.
  • the protective layer 17 can be formed by sputtering using a target material containing carbon, CVD (chemical vapor deposition) using a hydrocarbon source such as ethylene or toluene, or IBD (ion beam deposition).
  • a carbon-based protective layer is formed as the protective layer 17, it can be deposited by, for example, a DC magnetron sputtering method.
  • a carbon-based protective layer is formed as the protective layer 17, it is preferable to deposit an amorphous carbon protective layer by a plasma CVD method.
  • the amorphous carbon protective layer deposited by the plasma CVD method has a uniform surface with small roughness.
  • the lubricating layer 18 prevents contamination of the magnetic recording medium 10. In addition, the lubricating layer 18 reduces the frictional force of the magnetic head of the magnetic recording and reproducing device sliding on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10. 1, the lubricating layer 18 is formed on and in contact with the protective layer 17. The lubricating layer 18 is formed by applying the lubricant for a magnetic recording medium of the above-mentioned embodiment onto the protective layer 17. Thus, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.
  • the lubricating layer 18 bonds with the protective layer 17 with a high bonding strength, especially when the protective layer 17 disposed below the lubricating layer 18 is a carbon-based protective layer. As a result, even if the thickness of 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 ⁇ ), and more preferably 0.5 nm (5 ⁇ ) to 1.2 nm (12 ⁇ ).
  • the lubricating layer 18 is formed with a uniform thickness without being island-shaped or mesh-shaped. This allows the lubricating layer 18 to cover the surface of the protective layer 17 with a high coverage rate.
  • the lubricating layer 18 can be made sufficiently thin, and the flying height of the magnetic head can be sufficiently reduced.
  • Method of forming lubricating layer 18 includes, for example, preparing a magnetic recording medium in the middle of manufacture in which all layers up to the protective layer 17 are formed on the substrate 11, applying a solution for forming a lubricating layer onto the protective layer 17, and drying the solution.
  • the lubricant layer forming solution can be obtained by dispersing and dissolving the lubricant for magnetic recording media of the above-mentioned embodiment in a solvent as necessary, and adjusting the viscosity and concentration to be suitable for the coating method.
  • the solvent used in the lubricant layer forming solution include fluorine-based solvents such as Vertrel (registered trademark) XF (product name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.) and Asahiklin (registered trademark) AE-3000 (product name, manufactured by AGC).
  • the method for applying the solution for forming the lubricating layer is not particularly limited, but examples thereof include spin coating, spraying, paper coating, and dipping.
  • the dip method for example, the following method can be used.
  • the substrate 11 on which each layer up to the protective layer 17 has been formed is immersed in a lubricant layer forming solution placed in an immersion tank of a dip coater.
  • the substrate 11 is lifted from the immersion tank at a predetermined speed.
  • the lubricant layer forming solution is applied to the surface of the substrate 11 above the protective layer 17.
  • the lubricant layer forming solution can be applied uniformly onto the surface of the protective layer 17, and the lubricant layer 18 can be formed on the protective layer 17 with a uniform thickness.
  • the heat treatment temperature is preferably 100° C. to 180° C., and more preferably 100° C. to 160° C. If 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. Furthermore, by setting the heat treatment temperature to 180° C. or lower, thermal decomposition of the lubricating layer 18 due to the heat treatment can be prevented.
  • the heat treatment time can be appropriately adjusted depending on the heat treatment temperature, and is preferably 10 minutes to 120 minutes.
  • the lubricating layer 18 may be irradiated with ultraviolet (UV) light before or after the 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 sequentially provided on a substrate 11.
  • a lubricating layer 18 containing the above-mentioned fluorine-containing ether compound is formed on the protective layer 17. Even if the lubricating layer 18 is thin, it has good corrosion resistance and can suppress spin-off. Therefore, the magnetic recording medium 10 of this embodiment is excellent in reliability, especially corrosion resistance and spin-off suppression, and durability.
  • the magnetic recording medium 10 of this embodiment can contribute to reducing magnetic spacing, can reduce the magnetic head flying height (for example, 10 nm or less), and operates stably for a long period of time even in harsh environments associated with diversification of applications. Therefore, the magnetic recording medium 10 of this embodiment is particularly suitable as a magnetic disk to be mounted on a magnetic disk device of the LUL (Load Unload) type.
  • LUL Load Unload
  • Example 1 The compound represented by the above formula (AA) was obtained by the method described below. In a nitrogen gas atmosphere, 5 g of a compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH (where 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), 2.70 g of a compound represented by the above formula (5-1), and 5 mL of t-butanol were charged into a 100 mL recovery flask, and stirred at room temperature until homogenous to obtain a mixture. 0.30 g of potassium tert-butoxide was added to this mixture, and the mixture was reacted by stirring at 70° C. for 16 hours.
  • a compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH
  • the compound represented by formula (5-1) was synthesized by protecting the 1,2-diol moiety of 1,2,4-butanetriol with acetone, and then reacting the hydroxyl group at the 4-position with epibromohydrin.
  • reaction solution obtained after the reaction was returned to room temperature, 10 g of a 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 to a separatory funnel containing 25 mL of saturated sodium bicarbonate water, and extracted twice with 50 mL of ethyl acetate. The organic layer was washed with 25 mL of saline, 25 mL of saturated sodium bicarbonate water, and 25 mL of saline, in that order, and dehydrated with anhydrous sodium sulfate.
  • a 10% hydrogen chloride-methanol solution hydrogen chloride-methanol reagent (5-10%), manufactured by Tokyo Chemical Industry Co., Ltd.
  • Example 2 The compound represented by the above formula (AB) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-2) was used instead of the compound represented by formula (5-1), to obtain 3.85 g of compound (AB) (Rf 1 in formula (AB) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-2) was synthesized by protecting the 1,2-diol moiety of 1,2,6-hexanetriol with acetone, and then reacting the hydroxyl group at the 6-position with epibromohydrin.
  • Example 3 The compound represented by the above formula (AC) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-3) was used instead of the compound represented by formula (5-1), to obtain 3.85 g of compound (AC) (Rf 1 in formula (AC) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-3) was synthesized by protecting the 1,2-diol moiety of 1,2,8-octanetriol with acetone, and then reacting the hydroxyl group at the 8th position with epibromohydrin.
  • Example 4 The compound represented by the above formula (AD) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-4) was used instead of the compound represented by formula (5-1), to obtain 3.91 g of compound (AD) (Rf 1 in formula (AD) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-4) was synthesized by the following method. After protecting the 1,2-diol moiety of 1,2,4-butanetriol with acetone, the hydroxyl group at the 4-position was brominated and reacted with 3-buten-1-ol to obtain the compound. The vinyl group of the obtained compound was then oxidized with m-chloroperbenzoic acid (mCPBA) to synthesize the compound.
  • mCPBA m-chloroperbenzoic acid
  • Example 5 The compound represented by the above formula (AE) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), to obtain 3.26 g of compound (AE) (Rf 1 in formula (AE) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-5) was synthesized by reacting a compound in which the hydroxyl group of solketal (2,2-dimethyl-1,3-dioxolane-4-methanol) was brominated with 3-buten-1-ol, and then oxidizing the vinyl group of the resulting compound with m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • Example 6 The compound represented by the above formula (AF) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-6) was used instead of the compound represented by formula (5-1), to obtain 3.43 g of compound (AF) (Rf 1 in formula (AF) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-6) was synthesized by reacting a compound in which the hydroxyl group of solketal was brominated with 5-hexen-1-ol, and then oxidizing the vinyl group of the resulting compound with m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • Example 7 The compound represented by the above formula (AG) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-7) was used instead of the compound represented by formula (5-1), to obtain 3.56 g of compound (AG) (Rf 1 in formula (AG) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-7) was synthesized by reacting a compound in which the hydroxyl group of solketal was brominated with 7-octen-1-ol, and then oxidizing the vinyl group of the resulting compound with m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • Example 8 The compound represented by the above formula (AH) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-8) was used instead of the compound represented by formula (5-1), to obtain 3.40 g of compound (AH) (Rf 1 in formula (AH) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-8) was synthesized by the following method.
  • the epoxy group of 1,2-epoxy-5-hexene was ring-opened using dilute sulfuric acid.
  • the 1,2-diol moiety generated by the ring-opening was protected using acetone, and the vinyl group of the resulting compound was oxidized using m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • Example 9 The compound represented by the above formula (AI) was obtained by the method described 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), to obtain 3.45 g of compound (AI) (Rf 1 in formula (AI) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-9) was synthesized by the following method.
  • One of the vinyl groups of 1,7-octadiene was oxidized using m-chloroperbenzoic acid (mCPBA).
  • mCPBA m-chloroperbenzoic acid
  • the epoxy group generated by the oxidation was ring-opened using dilute sulfuric acid.
  • the 1,2-diol moiety generated by the ring-opening was protected using acetone, and the vinyl group of the resulting compound was oxidized using mCPBA to synthesize the compound.
  • Example 10 The compound represented by the above formula (AJ) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-10) was used instead of the compound represented by formula (5-1), to obtain 3.68 g of compound (AJ) (Rf 1 in formula (AJ) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-10) was synthesized by reacting one of the hydroxyl groups of 1,3-propanediol with a compound in which the hydroxyl group of solketal has been brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 11 The compound represented by the above formula (AK) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-11) was used instead of the compound represented by formula (5-1), to obtain 3.76 g of compound (AK) (Rf 1 in formula (AK) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-11) was synthesized by reacting one of the hydroxyl groups of 2,2-dimethyl-1,3-propanediol with a compound in which the hydroxyl group of solketal is brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 12 The compound represented by the above formula (AL) was obtained by the method described 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), to obtain 3.78 g of compound (AL) (Rf 1 in formula (AL) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-12) was synthesized by reacting one of the hydroxyl groups of 1,4-butanediol with a compound in which the hydroxyl group of solketal has been brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 13 The compound represented by the above formula (AM) was obtained by the method described 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), to obtain 3.85 g of compound (AM) (Rf 1 in formula (AM) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-13) was synthesized by reacting one of the hydroxyl groups of 2,3-dimethyl-1,4-butanediol with a compound in which the hydroxyl group of solketal has been brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 14 The compound represented by the above formula (AN) was obtained by the method described 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), to obtain 3.81 g of compound (AN) (Rf 1 in formula (AN) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-14) was synthesized by reacting one of the hydroxyl groups of 1,8-octanediol with a compound in which the hydroxyl group of solketal has been brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 15 The compound represented by the above formula (AO) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-15) was used instead of the compound represented by formula (5-1), to obtain 4.02 g of compound (AO) (Rf 1 in formula (AO) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-15) was synthesized by reacting one of the hydroxyl groups of 2,2,3,3-tetrafluoro-1,4-butanediol with a compound in which the hydroxyl group of solketal is brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 16 The compound represented by the above formula (AP) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-16) was used instead of the compound represented by formula (5-1), to obtain 4.31 g of compound (AP) (Rf 1 in formula (AP) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-16) was synthesized by reacting one of the hydroxyl groups of 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol with a compound in which the hydroxyl group of solketal is brominated, and then reacting the other hydroxyl group with epibromohydrin.
  • Example 17 The compound represented by the above formula (AQ) was obtained by the method shown below. In a nitrogen gas atmosphere, 5 g of a compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH (where 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), 4.50 g of 1-bromo-4-pentene, and 10 mL of N,N-dimethylformamide were charged into a 100 mL recovery flask, and stirred at room temperature until homogenized to obtain a mixture. 1.20 g of sodium hydride (purity 60%, containing mineral oil) was added to this mixture, and the mixture was reacted by stirring at 70°C for 16 hours.
  • sodium hydride purity 60%, containing mineral oil
  • the reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 50 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 purified by silica gel column chromatography to obtain 4.76 g of the compound represented by the following formula (7-1) as an intermediate compound.
  • Rf 1 in formula (7-1) is a PFPE chain represented by the above formula (4-1).
  • h representing the average degree of polymerization is 4.5
  • i representing the average degree of polymerization is 4.5.
  • Rf 1 in formula (7-2) is a PFPE chain represented by the above formula (4-1).
  • h representing the average degree of polymerization is 4.5
  • i representing the average degree of polymerization is 4.5.
  • reaction liquid obtained after the reaction was neutralized by adding 20 mL of saturated sodium bicarbonate water, and the resulting solid was filtered off. Then, the reaction liquid was transferred to a separatory funnel 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 3.32 g of compound (AQ) (Rf 1 in formula (AQ) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • Example 18 The compound represented by the above formula (AR) was obtained by the method described below. The same operation as in Example 17 was performed except that 1-bromo-7-octene was used instead of 1-bromo-4-pentene, to obtain 3.35 g of compound (AR) (Rf 1 in formula (AR) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h indicating the average degree of polymerization is 4.5, and i indicating the average degree of polymerization is 4.5).
  • 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 purified by silica gel column chromatography to obtain 7.21 g of the compound represented by the following formula (8) as intermediate compound 1.
  • Rf 1 in formula (8) is a PFPE chain represented by the above formula (4-1).
  • h representing the average degree of polymerization is 4.5
  • i representing the average degree of polymerization is 4.5.
  • reaction solution obtained after the reaction was returned to room temperature, 50 g of a 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 to a separatory funnel containing 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in that order, and dehydrated with anhydrous sodium sulfate.
  • a 10% hydrogen chloride-methanol solution hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.
  • Example 20 The compound represented by the above formula (BA) was obtained by the method described below. The same operation as in Example 19 was performed except that the compound represented by formula (5-17) was used instead of the compound represented by formula (5-5), to obtain 3.61 g of compound (BA) (Rf 1 in formula (BA) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-17) was synthesized by protecting the hydroxyl group of ethylene glycol monoallyl ether with dihydropyran and then oxidizing the vinyl group with m-chloroperbenzoic acid (mCPBA).
  • Example 21 The compound represented by the above formula (BB) was obtained by the method described below. The same operation as in Example 19 was performed except that the compound represented by formula (5-18) was used instead of the compound represented by formula (5-5), to obtain 3.61 g of compound (BB) (Rf 1 in formula (BB) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-18) was synthesized by the following method. Epichlorohydrin was reacted with twice the molar amount of 3-buten-1-ol. The hydroxyl group generated by the reaction was protected with dihydropyran. One of the vinyl groups of the compound obtained by the reaction was oxidized with m-chloroperbenzoic acid (mCPBA) to synthesize the compound.
  • mCPBA m-chloroperbenzoic acid
  • Example 22 The compound represented by the above formula (BC) was obtained by the method described below. The same operation as in Example 19 was performed except that the compound represented by formula (5-19) was used instead of the compound represented by formula (5-5), to obtain 3.53 g of compound (BC) (Rf 1 in formula (BC) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-19) was synthesized by reacting the hydroxyl group of 2-acetamidoethanol with epibromohydrin.
  • Example 23 The compound represented by the above formula (BD) was obtained by the method described below. The same operation as in Example 19 was performed except that the compound represented by formula (5-20) was used instead of the compound represented by formula (5-5), to obtain 3.72 g of compound (BD) (Rf 1 in formula (BD) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-20) was synthesized by reacting the hydroxyl group of 3-cyanopropanol with epibromohydrin.
  • Example 24 The compound represented by the above formula (BE) was obtained by the method described below. The same operation as in Example 19 was performed except that the compound represented by formula (5-21) was used instead of the compound represented by formula (5-5), to obtain 3.72 g of compound (BE) (Rf 1 in formula (BE) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-21) was synthesized by protecting the hydroxyl group of 3-buten-1-ol with dihydropyran and then oxidizing the vinyl group with m-chloroperbenzoic acid (mCPBA).
  • Example 25 The compound represented by the above formula (BF) was obtained by the method described below. The same operation as in Example 19 was performed except that the compound represented by formula (5-22) was used instead of the compound represented by formula (5-5), to obtain 3.72 g of compound (BF) (Rf 1 in formula (BF) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-22) was synthesized by protecting the two hydroxyl groups of 3-allyloxy-1,2-propanediol with dihydropyran and then oxidizing the vinyl group with m-chloroperbenzoic acid (mCPBA).
  • Example 26 The compound represented by the above formula (BG) was obtained by the method described below. The same operations as in Example 1 were carried out except that a compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by HOCH 2 CF 2 CF 2 O(CF 2 CF 2 O) j CF 2 CF 2 CH 2 OH ( in which j indicating the average degree of polymerization is 4.5) was used 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, to obtain 3.48 g of compound (BG) (Rf 2 in formula (BG) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j indicating the average degree of polymerization is 4.5).
  • Example 27 The compound represented by the above formula (BH) was obtained by the method described below. The same operations as in Example 1 were carried out except that a compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by HOCH 2 CF 2 O(CF 2 CF 2 O ) h ( CF 2 O ) i CF 2 CH 2 OH (k indicating the average degree of polymerization in the formula is 3.0) was used 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, to obtain 3.44 g of compound (BH) (Rf 3 in formula (BH) is a PFPE chain represented by the above formula (4-3). In Rf 3 , k indicating the average degree of polymerization is 3.0).
  • Example 28 The compound represented by the above formula (CA) was obtained by the method described below. The same operations as in Example 1 were carried out except that a compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) h (CF 2 O) i CF 2 CH 2 OH (wherein h indicating the average degree of polymerization is 7.0 and i indicating the average degree of polymerization is 0) was used 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 (wherein h indicating the average degree of polymerization is 7.0 and i indicating the average degree of polymerization is 0) was used 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 (wherein h indicating the average degree of polymerization is 4.5 and i indicating the average degree of polymerization is 4.5), to obtain 3.
  • Example 29 The compound represented by the above formula (CB) was obtained by the method described below. The same operation as in Example 28 was performed except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), to obtain 3.08 g of compound (CB) (Rf 1 in formula (CB) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0). The resulting compound (CB) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 30 The compound represented by the above formula (CC) was obtained by the method described below. The same operation as in Example 26 was performed except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), to obtain 3.24 g of compound (CC) (Rf 2 in formula (CC) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j representing the average degree of polymerization is 4.5). The obtained compound (CC) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 31 The compound represented by the above formula (CD) was obtained by the method described below. The same operation as in Example 27 was performed except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), to obtain 2.95 g of compound (CD) (Rf 3 in formula (CD) is a PFPE chain represented by the above formula (4-3). In Rf 3 , k indicating the average degree of polymerization is 3.0). The resulting compound (CD) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 32 The compound represented by the above formula (CE) was obtained by the method described below. The same operation as in Example 1 was performed except that the compound represented by formula (5-24) was used instead of the compound represented by formula (5-1), to obtain 3.35 g of compound (CE) (Rf 1 in formula (CE) is a PFPE chain represented by the above formula (4-1). In Rf 1 , h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-24) was synthesized by reacting one of the hydroxyl groups of 2-methyl-1,3-propanediol with a compound obtained by brominating the hydroxyl group of solketal, and then reacting the other hydroxyl group with epibromohydrin.
  • the obtained compound (CE) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 33 The compound represented by the above formula (CF) was obtained by the method shown below. In a nitrogen gas atmosphere, 5 g of a compound represented by HOCH 2 CF 2 CF 2 O(CF 2 CF 2 O) j CF 2 CF 2 CH 2 OH (j in the formula, which indicates the average degree of polymerization, is 4.5) (number average molecular weight: 1000, molecular weight distribution: 1.1), 4.83 g of a compound represented by the above formula (5-25), and 20 mL of N,N-dimethylformamide were charged into a 100 mL recovery flask, and stirred at room temperature until the mixture became homogenous to obtain a mixture.
  • a compound represented by the above formula (CF) was obtained by the method shown below. In a nitrogen gas atmosphere, 5 g of a compound represented by HOCH 2 CF 2 CF 2 O(CF 2 CF 2 O) j CF 2 CF 2 CH 2 OH (j in the formula, which indicates the average degree of polymerization
  • the compound represented by formula (5-25) was synthesized by the following method. First, the hydroxyl group of 3-buten-1-ol was protected using dihydropyran, and then the alkenyl group was oxidized with m-chloroperbenzoic acid. Then, the obtained compound was reacted with solketal, and the secondary hydroxyl group of the resulting compound was protected using chloromethyl methyl ether.
  • the obtained compound represented by the following formula (5-25A) was treated with an acid to selectively deprotect the THP group, and then the primary hydroxyl group was reacted with paratoluenesulfonyl chloride to obtain the compound represented by formula (5-25).
  • the selective deprotection of the THP group was performed by adding 0.52 g (2.07 mmol) of pyridinium p-toluenesulfonate as an acid catalyst to a mixture of 3.60 g (10.3 mmol) of the compound represented by formula (5-25A) and a mixed solvent of 16 g of 2-propanol and 16 g of acetone, and stirring the mixture in an air atmosphere at a reaction temperature of 55° C. for 7 hours.
  • reaction solution obtained after the reaction of the fluorine-based compound with the compound represented by formula (5-25) was returned to room temperature, 10 g of a 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 to a separatory funnel containing 25 mL of saturated sodium bicarbonate water, and extracted twice with 50 mL of ethyl acetate.
  • a 10% hydrogen chloride-methanol solution hydrogen chloride-methanol reagent (5-10%), manufactured by Tokyo Chemical Industry Co., Ltd.
  • Example 34 The compound represented by the above formula (CG) was obtained by the method described below. The same operation as in Example 33 was performed except that the compound represented by formula (5-26) was used instead of the compound represented by formula (5-25), to obtain 2.92 g of compound (CG) (Rf 2 in formula (CG) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j representing the average degree of polymerization is 4.5).
  • the compound represented by formula (5-26) was synthesized by the following method. First, the hydroxyl group of 5-hexen-1-ol was protected using dihydropyran, and then the alkenyl group was oxidized with m-chloroperbenzoic acid.
  • the resulting compound was then reacted with solketal, and the secondary hydroxyl group of the resulting compound was protected using chloromethyl methyl ether.
  • the resulting compound was treated with an acid to selectively deprotect the THP group, and then the primary hydroxyl group was reacted with paratoluenesulfonyl chloride to obtain the compound represented by formula (5-26).
  • the obtained compound (CG) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 35 The compound represented by the above formula (CH) was obtained by the method described below. In a nitrogen gas atmosphere, 12 g of a compound represented by HOCH 2 CF 2 CF 2 O(CF 2 CF 2 O) j CF 2 CF 2 CH 2 OH (j in the formula, which indicates the average degree of polymerization, is 4.5) (number average molecular weight: 1000, molecular weight distribution: 1.1), 1.81 g of a compound represented by the above formula (5-27), and 20 mL of N,N-dimethylformamide were charged into a 100 mL recovery flask, and stirred at room temperature until the mixture became homogenous to obtain a mixture.
  • a compound represented by the above formula (CH) was obtained by the method described below.
  • Example 36 The compound represented by the above formula (CI) was obtained by the method described below. The same operation as in Example 26 was performed except that the compound represented by formula (5-8) was used instead of the compound represented by formula (5-1), to obtain 3.13 g of compound (CI) (Rf 2 in formula (CI) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j representing the average degree of polymerization is 4.5). The obtained compound (CI) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 37 The compound represented by the above formula (CJ) was obtained by the method described below. The same operation as in Example 26 was performed except that the compound represented by formula (5-10) was used instead of the compound represented by formula (5-1), to obtain 3.52 g of compound (CJ) (Rf 2 in formula (CJ) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j representing the average degree of polymerization is 4.5). The obtained compound (CJ) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • Example 38 The compound represented by the above formula (CK) was obtained by the method described below. The same operation as in Example 26 was performed except that the compound represented by formula (5-15) was used instead of the compound represented by formula (5-1), to obtain 3.61 g of compound (CK) (Rf 2 in formula (CK) is a PFPE chain represented by the above formula (4-2). In Rf 2 , j representing the average degree of polymerization is 4.5). The resulting compound (CK) was subjected to 1 H-NMR and 19 F-NMR measurements, and the structure was identified from the following results.
  • R 1 , R 2 , and R 3 when the thus obtained compounds (AA) to (AS), (BA) to (BH), and (CA) to (CK) of Examples 1 to 38 are respectively substituted into formula (1) are shown in Tables 1 and 2.
  • Rf 2 in formula (ZA) is a PFPE chain represented by the above formula (4-2).
  • j representing the average degree of polymerization is 4.5.
  • Rf 2 in formula (ZB) is a PFPE chain represented by the above formula (4-2).
  • j representing the average degree of polymerization is 4.5.
  • Rf 1 in formula (ZC) is a PFPE chain represented by the above formula (4-1).
  • h representing the average degree of polymerization is 4.5
  • i representing the average degree of polymerization is 4.5.
  • Rf 2 in formula (ZD) is a PFPE chain represented by the above formula (4-2).
  • j representing the average degree of polymerization is 4.5.
  • Example 2 The same operations as in Example 1 were carried out, except that a compound represented by formula (5-23) was used instead of the compound represented by formula (5-1), and a compound represented by HOCH 2 CF 2 CF 2 O(CF 2 CF 2 O ) h (CF 2 O) i CF 2 CH 2 OH (numlecular weight 1000 , molecular weight distribution 1.1) (wherein j indicating the average degree of polymerization is 4.5 ) was used instead of the compound represented by formula (5-23) , and 2.81 g of compound (ZD) was obtained.
  • a compound represented by formula (5-23) was used instead of the compound represented by formula (5-1)
  • a compound represented by HOCH 2 CF 2 CF 2 O(CF 2 CF 2 O ) h (CF 2 O) i CF 2 CH 2 OH number average molecular weight 1000 , molecular weight distribution 1.1
  • Rf 1 in formula (ZE) is a PFPE chain represented by the above formula (4-1).
  • h representing the average degree of polymerization is 4.5
  • i representing the average degree of polymerization is 4.5.
  • a lubricant layer-forming solution was prepared using the compounds obtained in Examples 1 to 38 and Comparative Examples 1 to 5 by the method described below.
  • the lubricant layer-forming solution obtained was then used to form a lubricant layer for the magnetic recording medium by the method described below, thereby obtaining the magnetic recording media of Examples 1 to 38 and Comparative Examples 1 to 5.
  • “Lubricant layer forming solution” The compounds obtained in Examples 1 to 38 and Comparative Examples 1 to 5 were each dissolved in a fluorine-based solvent, Vertrel (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.), and applied onto the protective layer. The solution was diluted with Vertrel XF so that the film thickness upon application would be 9.0 ⁇ to 9.5 ⁇ , to prepare a solution for forming a lubricating layer.
  • Vertrel registered trademark
  • XF trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.
  • Magnetic recording media A magnetic recording medium was prepared by successively providing an adhesive layer, a soft magnetic layer, a first underlayer, a second underlayer, a magnetic layer, and a protective layer on a substrate having a diameter of 65 mm.
  • the protective layer was made of carbon.
  • the lubricant layer forming solutions of Examples 1 to 38 and Comparative Examples 1 to 5 were applied by dipping. The dipping was performed under the conditions of an immersion speed of 10 mm/sec, an immersion time of 30 sec, and a pull-up speed of 1.2 mm/sec.
  • the magnetic recording medium coated with the lubricant layer-forming solution was placed in a thermostatic chamber, and a heat treatment was performed at 120°C for 10 minutes to remove the solvent in the lubricant layer-forming solution and improve the adhesion between the protective layer and the lubricant layer, forming a lubricant layer on the protective layer and obtaining a magnetic recording medium.
  • Corrosion resistance evaluation criteria A+: less than 100 corrosion spots A: 100 or more but less than 300 corrosion spots B: 300 or more but less than 500 corrosion spots C: 500 or more but less than 1000 corrosion spots D: 1000 or more corrosion spots
  • spin-off property test The magnetic recording medium was mounted on a spin stand and rotated at a rotation speed of 10,000 rpm for 72 hours in an environment of 80° C. Before and after this operation, the thickness of the lubricating layer was measured at a position of a radius of 20 mm from the center of the magnetic recording medium using FT-IR, and the thickness reduction rate of the lubricating layer before and after the test was calculated. Using the calculated thickness reduction rate, the spin-off characteristics were evaluated according to the following evaluation criteria.
  • A Both the corrosion resistance test and the spin-off property test were A+ or A.
  • B Either the corrosion resistance test evaluation or the spin-off characteristic test evaluation is B, and the other is A+, A, or B.
  • C Either the corrosion resistance test rating or the spin-off characteristic test rating is C, and the other is A+, A, B, or C.
  • D At least one of the evaluations of the corrosion resistance test and the spin-off characteristic test is D.
  • At least one of R1 and R3 arranged at the end of the perfluoropolyether chain is an end group represented by formula (2), and the magnetic recording media of Examples 1 to 38 using the fluorine-containing ether compounds (AA) to (AS), (BA) to (BH), and (CA) to (CK) satisfying formula (1) were all rated A+, A, or B in the corrosion resistance test and spin-off characteristic test, and the overall rating was A or B. From this, it was confirmed that the lubricating layers of the magnetic recording media of Examples 1 to 38 have good corrosion resistance and can suppress spin-off.
  • the terminal group does not contain a 1,2-diol structure and a carbon atom that is not bonded to either a polar group or an ether oxygen atom.
  • the end groups of compound (ZA) do not contain a 1,2-diol structure, and all of the hydroxyl groups make a large contribution to increasing the polarity of the entire molecule.
  • the end groups of compound (ZA) do not contain carbon atoms that are not bonded to either a polar group or an ether oxygen atom, so the molecule does not have sufficient hydrophobicity. For these reasons, it is believed that in Comparative Example 1, the fluorine-containing ether compound is more likely to absorb water, which causes corrosion, and the result of the corrosion resistance test was D.
  • the distance between hydroxyl groups is greater than the distance between hydroxyl groups in a 1,2-diol structure, so all of the hydroxyl groups tend to interact with the protective layer. As a result, the interaction between the hydroxyl groups in the molecules is reduced, making the lubricant more likely to scatter as the magnetic recording medium rotates, which is thought to be why the spin-off characteristics test was rated C.
  • Compound (ZB) used in Comparative Example 2 and compound (ZC) used in Comparative Example 3 contain carbon atoms whose terminal groups are not bonded to either polar groups or ether oxygen atoms, but do not contain a 1,2-diol structure.
  • Compounds (ZB) and (ZC) have carbon atoms in their terminal groups that are not bonded to either polar groups or ether oxygen atoms, making the molecules more hydrophobic.
  • the total number of hydroxyl groups in compounds (ZB) and (ZC) is 4. Therefore, the total number of hydroxyl groups in compounds (ZB) and (ZC) is smaller than the total number of hydroxyl groups in compound (ZA) used in Comparative Example 1, which is 6. Therefore, in compounds (ZB) and (ZC), the fluorine-containing ether compounds are less likely to absorb water, which causes corrosion, and the results of the corrosion resistance tests in Comparative Examples 2 and 3 were better than those in Comparative Example 1.
  • the distance between hydroxyl groups is greater than the distance between hydroxyl groups in a 1,2-diol structure, so all of the hydroxyl groups are likely to interact with the protective layer.
  • the total number of hydroxyl groups in compounds (ZB) and (ZC) is four, which is relatively small, so there are almost no hydroxyl groups that can contribute to intermolecular interactions.
  • the intermolecular interactions of the fluorine-containing ether compound are small, and the lubricant is likely to scatter as the magnetic recording medium rotates, which is thought to be why Comparative Examples 2 and 3 received a D in the spin-off characteristics test.
  • the terminal group contains a 1,2-diol structure, but does not contain a carbon atom that is not bonded to either a polar group or an ether oxygen atom.
  • Compounds (ZD) and (ZE) have low hydrophobicity because the terminal groups do not contain carbon atoms that are not bonded to either polar groups or ether oxygen atoms. As a result, the fluorine-containing ether compounds are more likely to absorb water, which causes corrosion, and it is believed that this is why the corrosion resistance test result in Comparative Example 4 was C and the corrosion resistance test result in Comparative Example 5 was D. The reason why the corrosion resistance test results were C in Comparative Example 4 and D in Comparative Example 5 is believed to be because the total number of hydroxyl groups in compound (ZD) is 4 and the total number of hydroxyl groups in compound (ZE) is 8, making it easier for Comparative Example 5, which has a larger total number of hydroxyl groups, to absorb water.
  • a lubricant for magnetic recording media containing the fluorine-containing ether compound of the present invention it is possible to form a lubricating layer that has good corrosion resistance and can suppress spin-off, even if it is thin.

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06309654A (ja) * 1993-04-20 1994-11-04 Hitachi Maxell Ltd 磁気記録媒体
WO2004035656A1 (ja) * 2002-10-18 2004-04-29 Asahi Glass Company, Limited ペルフルオロポリエーテル誘導体
WO2005068534A1 (ja) * 2004-01-13 2005-07-28 Asahi Glass Company, Limited 含フッ素ポリエーテル化合物
WO2009013785A1 (ja) * 2007-07-23 2009-01-29 Fujitsu Limited 潤滑剤、磁気記録媒体およびヘッドスライダ
WO2015022871A1 (ja) * 2013-08-13 2015-02-19 旭硝子株式会社 含フッ素ポリエーテル化合物、潤滑剤、液状組成物および物品
US20200002640A1 (en) * 2018-07-02 2020-01-02 Seagate Technology Llc Polyfluoro lubricant compositions
WO2021002178A1 (ja) * 2019-07-03 2021-01-07 株式会社Moresco パーフルオロポリエーテル化合物、潤滑剤および磁気ディスク
WO2024024781A1 (ja) * 2022-07-29 2024-02-01 株式会社レゾナック 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
JP2024052300A (ja) * 2022-09-30 2024-04-11 株式会社Moresco フルオロポリエーテル化合物、潤滑剤、磁気ディスク、およびフルオロポリエーテル化合物の製造方法

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06309654A (ja) * 1993-04-20 1994-11-04 Hitachi Maxell Ltd 磁気記録媒体
WO2004035656A1 (ja) * 2002-10-18 2004-04-29 Asahi Glass Company, Limited ペルフルオロポリエーテル誘導体
WO2005068534A1 (ja) * 2004-01-13 2005-07-28 Asahi Glass Company, Limited 含フッ素ポリエーテル化合物
WO2009013785A1 (ja) * 2007-07-23 2009-01-29 Fujitsu Limited 潤滑剤、磁気記録媒体およびヘッドスライダ
WO2015022871A1 (ja) * 2013-08-13 2015-02-19 旭硝子株式会社 含フッ素ポリエーテル化合物、潤滑剤、液状組成物および物品
US20200002640A1 (en) * 2018-07-02 2020-01-02 Seagate Technology Llc Polyfluoro lubricant compositions
WO2021002178A1 (ja) * 2019-07-03 2021-01-07 株式会社Moresco パーフルオロポリエーテル化合物、潤滑剤および磁気ディスク
WO2024024781A1 (ja) * 2022-07-29 2024-02-01 株式会社レゾナック 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
JP2024052300A (ja) * 2022-09-30 2024-04-11 株式会社Moresco フルオロポリエーテル化合物、潤滑剤、磁気ディスク、およびフルオロポリエーテル化合物の製造方法

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