Fluorine-containing ether compound, lubricant for magnetic recording medium, and magnetic recording medium

Abstract

A fluorine-containing ether compound represented by formula (1): R1-[B]-[A]-CH2-R2 [-CH2-R3-CH2-R2] z-CH2-[C]-[D]-R4 (wherein [A] is represented by formula (2-1). [B] is represented by formula (2-2). [C] is represented by formula (3-1). [D] is represented by formula (3-2). And R4 is represented by formula (4). And R1 represents a terminal group which may be the same as or different from R4. Z is 1 or 2. And R2 is a perfluoropolyether chain. And R3 is represented by formula (5). ). # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a fluorine-containing ether compound, a lubricant for a magnetic recording medium, and a magnetic recording medium.

[0002] This application claims priority based on Japanese Patent Application No. 2022-094482 filed in Japan on June 10, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] In recent years, the amount of information processed via the Internet has increased dramatically. Along with this, the development of recording media for storing information has attracted much attention. In particular, magnetic recording media, which is a type of recording medium, is expected to be a container for increasing information because it can store large amounts of information at a low cost.

[0004] Generally speaking, in order to ensure the durability and reliability of magnetic recording media, a protective layer and a lubricating layer are provided on the magnetic layer (magnetic recording layer) of the magnetic recording medium. The lubricating layer disposed on the outermost surface of the magnetic recording medium is required to have various properties such as long-term stability, chemical resistance (preventing contamination by siloxane, etc.), wear resistance, and heat resistance.

[0005] As a lubricant used when forming a lubricating layer of a magnetic recording medium, for example, a lubricant containing a compound having a polar group such as a hydroxyl group at the terminal of a fluorine-based polymer having a repeating structure containing -CF2- has been proposed.

[0006] For example, Patent Documents 1, 2, and 3 disclose fluorine-containing ether compounds containing two perfluoropolyether chains in the molecule and having a linking group having a secondary hydroxyl group disposed between the two perfluoropolyether chains.

[0007] Patent Document 4 discloses a fluorine-containing ether compound including two perfluoropolyether chains in the molecule and a linking group having a primary hydroxyl group and a secondary hydroxyl group disposed between the two perfluoropolyether chains.

[0008] Patent Documents 5, 6 and 7 disclose fluorinated ether compounds having a skeleton in which three perfluoropolyether chains are linked via a linking group having a secondary hydroxyl group, and terminal groups having polar groups are linked to both sides of the skeleton via methylene groups (-CH2-).

[0009] Patent Document 8 discloses a method for producing a polyol (per)fluoropolyether derivative useful as a lubricant for magnetic media. Patent Document 8 describes that a protected triol having two protected hydroxyl functional groups and one free hydroxyl group is reacted with an activator to generate an activated protected triol, which is then subjected to a nucleophilic substitution reaction with a hydroxyl group disposed at the end of a functional (per)fluoropolyether derivative to generate a protected polyol (per)fluoropolyether derivative.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: International Publication No. 2021 / 251335

[0013] Patent Document 2: U.S. Patent Application Publication No. 2020 / 0002640

[0014] Patent Document 3: International Publication No. 2016 / 084781

[0015] Patent Document 4: International Publication No. 2021 / 019998

[0016] Patent Document 5: U.S. Patent Application Publication No. 2016 / 0260452

[0017] Patent Document 6: International Publication No. 2018 / 116742

[0018] Patent Document 7: International Publication No. 2017 / 145995

[0019] Patent Document 8: Japanese Patent No. 5334064 Summary of the invention

[0020] Problems to be solved by the invention

[0021] In recent years, as the applications of magnetic recording media have become more diverse, the environmental resistance required of magnetic recording media has become increasingly stringent. In response, the lubricating layer, which has a significant impact on the reliability and durability of magnetic recording media, has been required to have improved long-term stability.

[0022] As indicators of the long-term stability of the lubricating layer, the pickup characteristics and the shedding characteristics are known. The so-called pickup is a phenomenon in which the lubricant adheres to the magnetic head as a foreign matter (stain). The pickup affects the flight stability of the magnetic head. The so-called shedding is a phenomenon in which the lubricant is scattered or evaporated due to the centrifugal force and heat generated by the rotation of the magnetic recording medium. If shedding occurs, the film thickness of the lubricating layer is reduced, and thus the chemical resistance and wear resistance of the lubricating layer are deteriorated.

[0023] In addition, in recent years, towards the mass capacity of magnetic recording media, further magnetic spacing (distance between magnetic head and magnetic layer of magnetic recording medium) reduction and high speed of rotation speed of magnetic recording medium are required. However, if the floating height of magnetic head is low, it is easy to pick up. In addition, if the rotation speed of magnetic recording medium is fast, it is easy to fall off. In addition, if the thickness of lubricating layer is thinned in order to make the floating amount of magnetic head small, there is a tendency that the corrosion resistance of magnetic recording medium is reduced.

[0024] The present invention is proposed in view of the above situation, and its purpose is to provide a fluorine-containing ether compound that can form a lubricating layer that can form a thin layer, has a good effect of inhibiting corrosion of magnetic recording media, is not prone to pickup and falling off, and can be used as a material for a lubricant for magnetic recording media.

[0025] Another object of the present invention is to provide a lubricant for a magnetic recording medium comprising the fluorine-containing ether compound of the present invention.

[0026] Another object of the present invention is to provide a magnetic recording medium having a lubricating layer containing the fluorine-containing ether compound of the present invention, which is less likely to be picked up or peeled off and has excellent corrosion resistance.

[0027] Means for solving problems

[0028] That is, the present invention relates to the following matters.

[0029] [1] A fluorine-containing ether compound characterized by being represented by the following formula (1).

[0030] R 1 -[B]-[A]-CH2-R 2 [-CH2-R 3 -CH2-R 2 ] z -CH2-[C]-[D]-R 4 (1)

[0031] (In formula (1), [A] is represented by the following formula (2-1), where a in formula (2-1) is an integer of 0 to 3. [B] is represented by the following formula (2-2), where b in formula (2-2) is an integer of 0 to 3, and c is an integer of 2 to 5. The total value of a and b is 1 to 3. In formula (1), [A] and [B] are interchangeable. [C] is represented by the following formula (3-1), where d in formula (3-1) is an integer of 0 to 2. [D] is represented by the following formula (3-2), where e in formula (3-2) is an integer of 0 to 2, and f is an integer of 2 to 5. The total value of d and e is 1 or 2. In formula (1), [C] and [D] are interchangeable. R 4 is a branched terminal group having 3 to 30 carbon atoms and is represented by the following formula (4). L in the formula (4) represents an integer of 0 to 6. Y in the formula (4) 1 and Y 2 Each is independently a hydrocarbon group having only one primary hydroxyl group and may contain an ether oxygen atom. 3 is a hydrocarbon group having only one primary hydroxyl group, which may contain an ether oxygen atom, or a hydrogen atom. 1 For R 4The terminal groups may be the same or different and are branched terminal groups having 3 to 30 carbon atoms as represented by formula (4), organic groups having 1 to 30 carbon atoms having an ether oxygen atom at the terminal bonded to [A] or [B], or hydroxyl groups. z represents 1 or 2. R 2 is a perfluoropolyether chain. 2 or 3 R 2 Some or all of them may be the same, or they may be different. 3 is a divalent linking group represented by the following formula (5). In the formula (5), y1 is an integer of 1 to 3, and y2 is an integer of 1 to 3. The dotted line that is bonded to the oxygen atom on the left side in the formula (5) indicates the bond with R 1 The dotted line that is bonded to the methylene on the right side indicates the bond with R 4 When z is 2, the two R 3 They can be the same or different.)

[0032]

[0033] [2] The fluorinated ether compound according to [1], wherein R in the above formula (1) is 4 The above formula (4) is any one of the following formulas (6-1) to (6-3).

[0034]

[0035] (In formula (6-1), g represents an integer of 1 to 6. 1 and X 2 It is expressed by formula (7). 1 With X 2 Can be the same or different.)

[0036] (In formula (6-2), h represents an integer of 0 to 6. i and j each independently represent an integer of 1 to 6. 3 and X 4 It is represented by a hydrogen atom or by the formula (7). 3 With X 4 Can be the same or different.)

[0037] (In formula (6-3), k represents an integer of 0 to 6. p, q and r each independently represent an integer of 1 to 6. 5 , X 6 and X 7 It is represented by a hydrogen atom or by the formula (7). 5 , X 6 and X 7 They may be different from each other, or partly or completely the same.)

[0038] (In formula (7), s represents an integer of 2 to 6, and t represents 1 or 2.)

[0039] [3] The fluorinated ether compound according to [1] or [2], wherein R in the formula (1) 1 It is a branched terminal group having 3 to 30 carbon atoms represented by the above formula (4).

[0040] [4] The fluorinated ether compound according to [2], wherein R in the above formula (1) 1 and R 4 Both are branched terminal groups in any of the above formulae (6-1) to (6-3).

[0041] [5] The fluorinated ether compound according to any one of [1] to [4], wherein R in the formula (1) 1 -[B]-[A]-, and -[C]-[D]-R 4 same.

[0042] [6] The fluorinated ether compound according to any one of [1] to [5], wherein z in the formula (1) is 2, and the two R 3 The atoms contained in the R 2 Symmetrical configuration.

[0043] [7] The fluorinated ether compound according to any one of [1] to [6], wherein R in the formula (1) 1 It is represented by the following formula (8).

[0044]

[0045] (In formula (8), u represents an integer of 2 to 6, and v represents 0 or 1. R 5 is any one of a hydrogen atom, an alkyl group which may have a substituent not including a hydroxyl group, and an organic group having at least one double bond or triple bond. The alkyl group and the organic group may be straight-chain or branched.

[0046] [8] The fluorinated ether compound according to [7], wherein R in the formula (8) 5 It is an alkyl group having 1 to 6 carbon atoms.

[0047] [9] The fluorinated ether compound according to [7], wherein R in the above formula (8) 5 It is an alkyl group having 1 to 6 carbon atoms and having a substituent, wherein the substituent is a fluoro group or a cyano group.

[0048]

[10] The fluorinated ether compound according to [7], wherein R in the above formula (8) 5It is any one of an organic group having 6 to 12 carbon atoms having an aromatic hydrocarbon, an organic group having 3 to 10 carbon atoms having an aromatic heterocycle, an alkenyl group having 2 to 8 carbon atoms, and an alkynyl group having 3 to 8 carbon atoms.

[0049]

[11] The fluorinated ether compound according to [7], wherein R in the above formula (8) 5 It is one group selected from methyl, ethyl, n-propyl, isopropyl, 2,2,2-trifluoroethyl, 2,2,3,3,3-pentafluoropropyl, 2,2,2,2,2,2-hexafluoroisopropyl, 2-cyanoethyl, 3-cyanopropyl, 4-cyanobutyl, phenyl, methoxyphenyl, cyanophenyl, phenethyl, thienylethyl, N-methylpyrazolylmethyl, allyl, 3-butenyl, 4-pentenyl, propargyl, 3-butynyl, and 4-pentynyl.

[0050]

[12] The fluorinated ether compound according to [7], wherein R in the above formula (8) 5 A hydrogen atom.

[0051]

[13] The fluorinated ether compound according to any one of [1] to

[12] , wherein two or three R in the formula (1) are 2 Each is independently a perfluoropolyether chain represented by the following formula (9).

[0052] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(9)

[0053] (In formula (9), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20. However, w2, w3, w4, and w5 are not all 0 at the same time. w1 and w6 represent average values ​​of the number of CF2, and each independently represents 1 to 3. There is no particular limitation on the order of arrangement of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) as repeating units in formula (9).)

[0054]

[14] The fluorinated ether compound according to any one of [1] to

[12] , wherein two or three R in the formula (1) are 2 Each independently represents any one selected from the group consisting of perfluoropolyether chains represented by the following formulae (10-1) to (10-4).

[0055] -CF2-(OCF2CF2) l-(OCF2) m -OCF2-(10-1)

[0056] (In formula (10-1), l and m represent average polymerization degrees, l represents 0.1 to 20, and m represents 0 to 20.)

[0057] -CF2CF2-(OCF2CF2CF2) n -OCF2CF2-(10-2)

[0058] (In formula (10-2), n represents an average degree of polymerization and is 0.1 to 15.)

[0059] -CF2CF2CF2-(OCF2CF2CF2CF2) o -OCF2CF2CF2-(10-3)

[0060] (In formula (10-3), o represents an average degree of polymerization and is 0.1 to 10.)

[0061] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(10-4)

[0062] (In formula (10-4), w8 and w9 represent average polymerization degrees, and each independently represents 0.1 to 20. w7 and w10 represent average values ​​of the number of CF2, and each independently represents 1 to 2.)

[0063]

[15] The fluorinated ether compound according to any one of [1] to

[14] , wherein the number average molecular weight is within the range of 500 to 10,000.

[0064]

[16] A lubricant for a magnetic recording medium, comprising the fluorine-containing ether compound according to any one of [1] to

[15] .

[0065]

[17] A magnetic recording medium, characterized in that at least a magnetic layer, a protective layer and a lubricating layer are provided in this order on a substrate,

[0066] The lubricating layer contains the fluorine-containing ether compound according to any one of [1] to

[15] .

[0067]

[18] The magnetic recording medium according to

[17] , wherein the average film thickness of the lubricating layer is 0.5 nm to 2.0 nm.

[0068] Effects of the Invention

[0069] The fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is suitable as a material for a lubricant for a magnetic recording medium.

[0070] The lubricant for magnetic recording media of the present invention contains the fluorine-containing ether compound of the present invention, so that a lubricating layer can be formed which has a good effect of suppressing corrosion of the magnetic recording medium even if the thickness is thin, has good adhesion with the protective layer, and can suppress picking up and falling off.

[0071] The magnetic recording medium of the present invention has a lubricating layer that has good adhesion to the protective layer, can suppress pickup and fall-off, and can obtain excellent corrosion resistance. Therefore, it has excellent reliability and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic cross-sectional view showing an example of an embodiment of the magnetic recording medium of the present invention. DETAILED DESCRIPTION

[0073] In order to solve the above-mentioned problems, the present inventors paid attention to the relationship between the molecular structure of the fluorine-containing ether compound contained in the lubricating layer and the protective layer, and conducted intensive studies as shown below.

[0074] In the past, as the material of the magnetic recording medium lubricant (hereinafter, sometimes abbreviated as "lubricant") coated on the surface of the protective layer, a fluorine-containing ether compound having a polar group such as a hydroxyl group at the end of the chain structure was used. However, the lubricating layer formed using the previous lubricant can not fully obtain the adhesion of the protective layer and / or the effect of suppressing the corrosion of the magnetic recording medium. In addition, the inventors have conducted in-depth research, and it can be seen that if the adhesion of the lubricating layer to the protective layer is insufficient, it is easy to pick up and fall off.

[0075] Therefore, the inventors have repeatedly studied to improve the adhesion of the lubricating layer to the protective layer and the effect of inhibiting the corrosion of the magnetic recording medium. As a result, it is known that as a lubricant, a fluorinated ether compound having a hydroxyl group and a fluorinated ether compound capable of obtaining the functions of <1> to <3> shown below is required.

[0076] <1> The hydroxyl groups in the perfluoropolyether (hereinafter, sometimes referred to as PFPE)-based compound effectively participate in bonding with active sites on the protective layer.

[0077] <2> The hydroxyl group in the PFPE-based compound participates in the formation of hydrogen bonds between molecules of the PFPE-based compounds.

[0078] <3> Sufficient hydrophobicity due to the inclusion of perfluoropolyether chains (PFPE chains) can be obtained, and the PFPE chains are not excessively separated from the protective layer.

[0079] Therefore, the present inventors have repeatedly studied the molecular structure of a fluorine-containing ether compound that can effectively obtain the functions of <1> to <3> described above.

[0080] As a result, it was found that as long as two or three perfluoropolyether chains (PFPE chains) are made to be combined via a methylene group (-CH2-) and a specific bivalent linking group having a secondary hydroxyl group, the perfluoropolyether chains at both ends are respectively combined via a methylene group (-CH2-) with a specific linking group having a secondary hydroxyl group, and a fluorinated ether compound having a branched terminal group having a plurality of primary hydroxyl groups is configured at at least one end. Furthermore, it was confirmed that the lubricating layer containing such a fluorinated ether compound has a high effect of suppressing the corrosion of the magnetic recording medium even if the thickness is thin, and can suppress picking up and falling off, thereby conceiving the present invention.

[0081] Below, fluorine-containing ether compound of the present invention, magnetic recording medium lubricant and magnetic recording medium are described in detail. In addition, the present invention is not limited only to the embodiment shown below. For example, the present invention is not limited only to the following examples, and within the scope not exceeding the purpose of the present invention, number, amount, ratio, composition, kind, position, material, formation etc. can be added, omitted, replaced, changed.

[0082] [Fluorinated ether compounds]

[0083] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

[0084] R 1 -[B]-[A]-CH2-R 2 [-CH2-R 3 -CH2-R 2 ] z -CH2-[C]-[D]-R 4 (1)

[0085] (In formula (1), [A] is represented by the following formula (2-1), where a in formula (2-1) is an integer of 0 to 3. [B] is represented by the following formula (2-2), where b in formula (2-2) is an integer of 0 to 3, and c is an integer of 2 to 5. The total value of a and b is 1 to 3. In formula (1), [A] and [B] are interchangeable. [C] is represented by the following formula (3-1), where d in formula (3-1) is an integer of 0 to 2. [D] is represented by the following formula (3-2), where e in formula (3-2) is an integer of 0 to 2, and f is an integer of 2 to 5. The total value of d and e is 1 or 2. In formula (1), [C] and [D] are interchangeable. R 4 is a branched terminal group having 3 to 30 carbon atoms and is represented by the following formula (4). L in the formula (4) represents an integer of 0 to 6. Y in the formula (4) 1 and Y 2Each is independently a hydrocarbon group having only one primary hydroxyl group and may contain an ether oxygen atom. 3 is a hydrocarbon group having only one primary hydroxyl group, which may contain an ether oxygen atom, or a hydrogen atom. 1 For R 4 The terminal groups may be the same or different and are branched terminal groups having 3 to 30 carbon atoms as represented by formula (4), organic groups having 1 to 30 carbon atoms having an ether oxygen atom at the terminal bonded to [A] or [B], or hydroxyl groups. z represents 1 or 2. R 2 is a perfluoropolyether chain. 2 or 3 R 2 Some or all of them may be the same, or they may be different. 3 is a divalent linking group represented by the following formula (5). In the formula (5), y1 is an integer of 1 to 3, and y2 is an integer of 1 to 3. The dotted line that is bonded to the oxygen atom on the left side in the formula (5) indicates the bond with R 1 The dotted line that is bonded to the methylene on the right side indicates the bond with R 4 When z is 2, the two R 3 They can be the same or different.)

[0086]

[0087] (-[B]-[A]-represented linker)

[0088] In the fluorinated ether compound of the present embodiment represented by formula (1), [A] is represented by the above formula (2-1), and [B] is represented by the above formula (2-2). [A] and [B] in formula (1) are divalent linking groups. [A] and [B] in formula (1) are interchangeable. a in formula (2-1) and b in formula (2-2) are integers of 0 to 3. The total value of a and b is 1 to 3.

[0089] From the viewpoint of raw material availability and ease of synthesis, Formula (2-1) and Formula (2-2) are preferably a combination in which a is 1 and b is 0, or a combination in which a is 0 and b is 1.

[0090] In addition, from the viewpoint of adhesion to the protective layer, the combination of a being 2 and b being 0, or the combination of a being 1 and b being 1 is preferably used for formula (2-1) and formula (2-2). In particular, when a is 2 and b is 0, the directions in which the two hydroxyl groups of formula (2-1) are arranged in the fluorinated ether compound are three-dimensionally the same direction relative to the extension direction of the PFPE chain, and the two hydroxyl groups of formula (2-1) tend to be easily adsorbed to the protective layer. In addition, when a and b are 1 and the bonding order of [A] and [B] is from R to B, the bonding order of [A] and [B] is from R to B. 1When the side is -[A]-[B]-, the distance between the hydroxyl groups contained in the -[A]-[B]- structure becomes greater. Therefore, the intramolecular hydrogen bond of the fluorine-containing ether compound represented by formula (1) can be reduced, and the affinity with the protective layer can be increased.

[0091] In formula (2-2), c is an integer of 2 to 5. When b is an integer of 1 to 3, c is preferably an integer of 2 to 4, and most preferably 2. This is because the number of carbon atoms contained in the -[B]-[A]- structure is not too large, and a fluorine-containing ether compound can form a lubricating layer that has better adhesion to the protective layer and can suppress pickup and falling off.

[0092] (Linking group represented by -[C]-[D]-)

[0093] In the fluorinated ether compound of the present embodiment represented by formula (1), [C] is represented by the above formula (3-1), and [D] is represented by the above formula (3-2). [C] and [D] in formula (1) are divalent linking groups. [C] and [D] in formula (1) are interchangeable. d in formula (3-1) and e in formula (3-2) are integers of 0 to 2. The sum of the values ​​of d and e is 1 or 2.

[0094] From the viewpoint of raw material availability and ease of synthesis, Formula (3-1) and Formula (3-2) are preferably a combination in which d is 1 and e is 0, or a combination in which d is 0 and e is 1.

[0095] In addition, from the viewpoint of adhesion to the protective layer, the combination of d being 2 and e being 0, or the combination of d being 1 and e being 1 is preferably used in formula (3-1) and formula (3-2). In particular, when d is 2 and e is 0, the directions in which the two hydroxyl groups of formula (3-1) are arranged in the fluorinated ether compound are three-dimensionally the same direction relative to the extension direction of the PFPE chain, and the two hydroxyl groups of formula (3-1) tend to be easily adsorbed to the protective layer. In addition, when d and e are 1 and the bonding order of [C] and [D] is from R to C, the bonding order of [C] and [D] is from R to D. 2 When the side is -[D]-[C]-, the distance between the hydroxyl groups contained in the -[D]-[C]- structure becomes greater. Therefore, the intramolecular hydrogen bond of the fluorine-containing ether compound represented by formula (1) can be reduced, and the affinity with the protective layer can be increased.

[0096] In formula (3-2), f is an integer of 2 to 5. When e is an integer of 1 to 2, f is preferably an integer of 2 to 3, and most preferably 2. This is because the number of carbon atoms contained in the -[C]-[D]- structure is not too large, and a fluorine-containing ether compound can form a lubricating layer that has better adhesion to the protective layer and can suppress pickup and falling off.

[0097] (R4 The branched end groups shown)

[0098] In formula (1), R 4 It is represented by formula (4) and is a branched terminal group having 3 to 30 carbon atoms. 4 The number of carbon atoms in R is preferably 3 to 20, more preferably 3 to 12. 4 The number of carbon atoms in can be 3 to 5, 5 to 10, 10 to 15, etc. 4 When the number of carbon atoms in the fluorine-containing ether compound is 3 to 12, the ratio of fluorine atoms in the fluorine-containing ether compound molecule is reduced, and the increase in the surface free energy of the entire molecule can be suppressed.

[0099] Formula (4) is a branched terminal group containing 2 or 3 primary hydroxyl groups with carbon atoms as branch points. 4 The contained plurality of primary hydroxyl groups participate in the formation of hydrogen bonds between molecules of the fluorine-containing ether compound.

[0100] L in formula (4) represents an integer of 0 to 6. In formula (4), Y 1 and Y 2 Each is independently a hydrocarbon group having only one primary hydroxyl group and may contain an ethereal oxygen atom. 1 and Y 2 The hydrocarbon group shown may be a straight chain or a branched chain, and preferably does not contain secondary hydroxyl groups and tertiary hydroxyl groups. 3 is a hydrocarbon group having only one primary hydroxyl group, which may contain an ether oxygen atom, or a hydrogen atom. 3 The hydrocarbon group shown may be straight chain or branched, and preferably does not contain secondary or tertiary hydroxyl groups.

[0101] R 4 It is preferred to contain three or more ether bonds (-O-). In this case, since R 4 Since the fluorinated ether compound represented by the formula (1) has appropriate flexibility, the lubricating layer containing the fluorinated ether compound represented by the formula (1) has more excellent adhesion with the protective layer.

[0102] In R 4 When there are multiple ether bonds, adjacent ether bonds are preferably bonded to each other via a linking group having two or more carbon atoms connected. In this case, the distance between adjacent ether bonds becomes appropriate, and the fluorine-containing ether compound is less likely to aggregate.

[0103] Represents R 4 The formula (4) is preferably any branched terminal group in the following formulas (6-1) to (6-3). 4 In the case of any branched terminal group in formulas (6-1) to (6-3), R 4 The carbon atoms to which the primary hydroxyl groups are bound are bound to each other via a linking group containing methine and / or methylene and an ether bond.4 The distance between adjacent primary hydroxyl groups becomes appropriate, R 4 The plurality of primary hydroxyl groups possessed by the fluorinated ether compound are arranged so as to facilitate hydrogen bonding between molecules of the fluorinated ether compound. 4 is any branched terminal group in the following formulas (6-1) to (6-3), then R 4 The molecular weight of R is large, so the proportion of fluorine atoms in the fluorine-containing ether compound molecule is reduced, which can suppress the increase of the surface free energy of the entire molecule. 4 More preferred is formula (6-1) or (6-2).

[0104]

[0105] (In formula (6-1), g represents an integer of 1 to 6. 1 and X 2 It is expressed by formula (7). 1 With X 2 Can be the same or different.)

[0106] (In formula (6-2), h represents an integer of 0 to 6. i and j each independently represent an integer of 1 to 6. 3 and X 4 It is represented by a hydrogen atom or by the formula (7). 3 With X 4 Can be the same or different.)

[0107] (In formula (6-3), k represents an integer of 0 to 6. p, q and r each independently represent an integer of 1 to 6. 5 , X 6 and X 7 It is represented by a hydrogen atom or by the formula (7). 5 , X 6 and X 7 They may be different from each other, or partly or completely the same.)

[0108] (In formula (7), s represents an integer of 2 to 6, and t represents 1 or 2.)

[0109] In formula (6-1), g represents an integer of 1 to 6. In order to easily ensure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, g is preferably an integer of 1 to 4, and more preferably 1 or 2. In addition, when g is an integer of 1 to 4, R 4 The number of carbon atoms in the fluorine-containing ether is large, so the mobility of the terminal is not too high. Therefore, it is preferred to form a lubricating layer that has better adhesion to the protective layer and can suppress picking up and falling off.

[0110] X1 and X 2 It is expressed by formula (7). 1 With X 2 Can be the same or different.

[0111] In formula (6-2), h represents an integer of 0 to 6. In order to easily ensure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, h is preferably an integer of 0 to 4, and more preferably an integer of 0 to 2. In addition, when h is an integer of 0 to 5, R 4 The number of carbon atoms in the fluorine-containing ether is large, so the mobility of the terminal is not too high. Therefore, it is preferred to form a lubricating layer that has better adhesion to the protective layer and can suppress picking up and falling off.

[0112] In formula (6-2), i and j each independently represent an integer of 1 to 6. In order to easily ensure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, i and j each independently represent an integer of preferably 1 to 4, and more preferably 1 or 2. i and j may be the same or different. In order to facilitate the production of the fluorine-containing ether compound, i and j are preferably the same.

[0113] X 3 and X 4 It is represented by a hydrogen atom or by the formula (7). 3 With X 4 Can be the same or different.

[0114] In the formula (6-3), k represents an integer of 0 to 6. In order to easily secure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, k is preferably an integer of 0 to 4, more preferably an integer of 0 to 2.

[0115] p, q and r each independently represent an integer of 1 to 6. In order to easily ensure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, p, q and r each independently preferably represent an integer of 1 to 4, and more preferably 1 or 2. p, q and r may be different from each other, or may be partially or entirely the same. In order to facilitate the production of the fluorine-containing ether compound, p, q and r are preferably all the same.

[0116] X 5 , X 6 and X 7 It is represented by a hydrogen atom or by the formula (7). 5 , X 6 and X 7 They may be different from each other, or may be partially or entirely the same.

[0117] In formula (7), s represents an integer of 2 to 6. In order to easily secure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, s is preferably an integer of 2 to 4, more preferably 2 or 3.

[0118] t represents 1 or 2. When t is 2, each [-(CH2) s In order to easily ensure the ratio of fluorine atoms in the fluorine-containing ether compound molecule, t is preferably 1.

[0119] As X in formula (6-1) 2 In the formula (7), s is preferably 3 or more, and / or t is 2, and more preferably X in the formula (6-1) 1 Formula (7) and as X in formula (6-1) 2 In formula (7), s is greater than 3 and / or t is 2. This is because the distance from the carbon atom that becomes the branch point to the primary hydroxyl group in formula (6-1) is not too close and becomes appropriate, thereby forming a fluorinated ether compound that can form a lubricating layer that can more effectively suppress pickup and shedding.

[0120] -[C]-[D]-R of formula (1) 4 Specifically, it is preferably any one of the structures represented by the following formulas (11-1) to (11-25). In order to become a fluorine-containing ether compound that can form a lubricating layer that can effectively inhibit picking up and falling off, it is more preferably any one of the structures represented by the following formulas (11-1) to (11-5), (11-7) to (11-10), (11-13) to (11-21), (11-24), and (11-25).

[0121]

[0122]

[0123]

[0124] (R 1 terminal groups shown)

[0125] In formula (1), R 1 The terminal groups shown are 4 The terminal groups may be the same or different and are branched terminal groups having 3 to 30 carbon atoms as represented by formula (4), organic groups having 1 to 30 carbon atoms having an ether oxygen atom at the terminal bonded to [A] or [B], or hydroxyl groups. 1 The terminal groups shown above can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, and the like.

[0126] In R 1 In the case of a terminal group having 3 to 30 carbon atoms represented by formula (4), R 1 It becomes a branched terminal group containing 2 or 3 primary hydroxyl groups with carbon atoms as branch points. 1The contained plurality of primary hydroxyl groups participate in the formation of hydrogen bonds between molecules of the fluorine-containing ether compounds, thereby further strengthening the hydrogen bonds between molecules of the fluorine-containing ether compounds.

[0127] In R 1 In the case of a terminal group represented by formula (4), R 1 The formula (4) is preferably any branched terminal group in the above formulas (6-1) to (6-3). In this case, the preferred values ​​of g in formula (6-1), h to j in formula (6-2), k, p to r in formula (6-3), and s and t in formula (7) are the same as R 4 The same applies to any branched terminal group in formulae (6-1) to (6-3).

[0128] In R 1 In the case of a terminal group represented by formula (4), -[A]-[B]-R 1 Specifically, the structures represented by the above formulae (11-1) to (11-25) are preferred.

[0129] In formula (1), R 1 In the case of the terminal group represented by formula (4), it is more preferred that R 1 and R 4 Both are branched terminal groups in any of the above formulae (6-1) to (6-3).

[0130] In formula (1), R 1 In the case of a terminal group represented by formula (4), R 1 With R 4 Same, more preferably R 1 and R 4 Both are branched terminal groups in any of the above formulae (6-1) to (6-3).

[0131] In the fluorine-containing ether compound of this embodiment represented by formula (1), R 1 When it is not a branched terminal group represented by formula (4), R 1 is an organic group having 1 to 30 carbon atoms and having an ether oxygen atom at the terminal bonded to [A] or [B], or a hydroxyl group. 1 Preferably, it is a terminal group represented by the following formula (8). In this case, R 1 The molecular weight of the fluorine-containing ether compound is large, so that the ratio of fluorine atoms in the fluorine-containing ether compound molecule is reduced, and the increase in the surface free energy of the entire molecule can be suppressed.

[0132]

[0133] (In formula (8), u represents an integer of 2 to 6, and v represents 0 or 1. R 5is any one of a hydrogen atom, an alkyl group which may have a substituent not including a hydroxyl group, and an organic group having at least one double bond or triple bond. The alkyl group and the organic group may be straight-chain or branched.

[0134] In formula (8), u represents an integer of 2 to 6, and v represents 0 or 1. When v in formula (8) is 0, the ratio of fluorine atoms in the fluorine-containing ether compound molecule is reduced, which can more effectively suppress the increase in the surface free energy of the entire molecule. When v is 1, since the ether bond contained in formula (8) imparts flexibility to the fluorine-containing ether compound represented by formula (1), it is easier to adsorb to the protective layer.

[0135] When v in formula (8) is 1, since u is an integer from 2 to 6, R 1 The terminal group shown is chemically stable and is not easily decomposed. u is preferably an integer of 2 to 4, more preferably 2 or 3. When u is 2 or 3, the ratio of fluorine atoms in the fluorine-containing ether compound molecule decreases, and the increase in the surface free energy of the entire molecule can be suppressed.

[0136] R in formula (8) 5 It is any of a hydrogen atom, an alkyl group which may have a substituent not including a hydroxyl group, and an organic group having at least one double bond or triple bond.

[0137] In R 5 When R is a hydrogen atom, 5 Together with the oxygen atom in formula (8), a hydroxyl group is formed. When v in formula (8) is 1, R 1 is an alkoxy group having a hydroxyl group at the end. When v in formula (8) is 0, R 1 It is hydroxyl.

[0138] In R 5 When is a hydrogen atom and v in formula (8) is 1, R represented by formula (8) 1 Preferred specific examples include -O-CH2CH2-OH (u in formula (8) is 2) and -O-CH2CH2CH2-OH (u in formula (8) is 3).

[0139] In R 5 is a hydrogen atom, and v in formula (8) is 0 (i.e., R 1 In the case of hydroxyl group, R 1 It can be combined with [A] shown in formula (2-1) or [B] shown in formula (2-2). 1 When combined with [B], R 1 The distance between the hydroxyl groups shown and the adjacent hydroxyl groups becomes more appropriate, which is preferred.

[0140] In R 5 In the case of an alkyl group which may have a substituent not containing a hydroxyl group, examples of the substituent include a fluoro group, a cyano group, an alkoxy group, etc. The substituents described above do not include a substituent containing a hydroxyl group such as a hydroxyl group and an alkoxy group.

[0141] The alkyl group which may have a substituent is preferably an alkyl group having 1 to 6 carbon atoms which has no substituent or an alkyl group having 1 to 6 carbon atoms which has a substituent. The substituent possessed by the alkyl group having 1 to 6 carbon atoms which has a substituent is preferably a fluoro group or a cyano group. The alkyl group having 1 to 6 carbon atoms which has a substituent is a group in which one or more hydrogen atoms possessed by the alkyl group are substituted by a substituent, or a group in which all hydrogen atoms possessed by the alkyl group are substituted by substituents.

[0142] The alkyl group of the unsubstituted alkyl group having 1 to 6 carbon atoms and the alkyl group of the substituted alkyl group having 1 to 6 carbon atoms may be linear or branched. Specifically, examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl and its structural isomers, and n-hexyl and its structural isomers.

[0143] Examples of the alkyl group having 1 to 6 carbon atoms in which one or more hydrogen atoms are substituted by a fluorine group include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 2,2,2,2,2,2-hexafluoroisopropyl group, a 2,2,3,3,4,4,4-heptafluorobutyl group, a 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, and a 2,2,3,3,4,4,5,5,6,6,6-undecafluorohexyl group.

[0144] The number of cyano groups in the alkyl group having 1 to 6 carbon atoms in which at least one hydrogen atom is replaced by a cyano group may be 1 or 2 or more. If the number of cyano groups is large, the polarity of the fluorine-containing ether compound is too high, so the number of cyano groups is preferably 2 or less, and most preferably 1.

[0145] Examples of the alkyl group having 1 to 6 carbon atoms in which one or more hydrogen atoms are substituted with a cyano group include 2-cyanoethyl, 3-cyanopropyl, 4-cyanobutyl, 5-cyanopentyl, 6-cyanohexyl, 2-cyano-1-methylethyl and 2,2'-dicyanoisopropyl.

[0146] As the organic group having at least one double bond or triple bond, any one of an organic group having 6 to 12 carbon atoms having an aromatic hydrocarbon, an organic group having 3 to 10 carbon atoms having an aromatic heterocycle, an alkenyl group having 2 to 8 carbon atoms, and an alkynyl group having 3 to 8 carbon atoms is preferred. The organic group having at least one double bond or triple bond may be straight-chain or branched. The organic group having at least one double bond or triple bond may have a substituent that does not contain a hydroxyl group.

[0147] Examples of the organic group having 6 to 12 carbon atoms having an aromatic hydrocarbon include phenyl, methoxyphenyl, dimethoxyphenyl, cyanophenyl, dicyanophenyl, fluorophenyl, naphthyl, methoxynaphthyl, benzyl, methoxybenzyl, phenethyl, methoxyphenethyl, fluorophenethyl, naphthylmethyl, and naphthylethyl. When the aromatic hydrocarbon has a substituent, the position where the substituent is bonded may be any position.

[0148] Examples of the organic group having 3 to 10 carbon atoms and having an aromatic heterocyclic ring include pyrrolyl, pyrazolyl, methylpyrazolylmethyl, imidazolyl, furanyl, furfuryl, Azolyl, iso oxazolyl, thienyl, thienylmethyl, thienylethyl, thiazolyl, methylthiazolylethyl, isothiazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, indolinyl, benzofuranyl, benzothienyl, benzimidazolyl, benzo Azolyl, benzothiazolyl, benzopyrazolyl, benzisophthalic acid oxazolyl, benzisothiazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, phthalazinyl, and cinnolinyl.

[0149] Examples of the alkenyl group having 2 to 8 carbon atoms include vinyl, allyl, 1-propenyl, isopropenyl, 3-butenyl and structural isomers thereof, 4-pentenyl and structural isomers thereof, 5-hexenyl and structural isomers thereof, 6-heptenyl and structural isomers thereof, and 7-octenyl and structural isomers thereof.

[0150] Examples of the alkynyl group having 3 to 8 carbon atoms include 1-propynyl, propargyl, 3-butynyl and structural isomers thereof, 4-pentynyl and structural isomers thereof, 5-hexynyl and structural isomers thereof, 6-heptynyl and structural isomers thereof, and 7-octynyl and structural isomers thereof.

[0151] From the viewpoint of availability and / or ease of synthesis, R in formula (8) 5It is preferably one group selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 2,2,2,2,2,2-hexafluoroisopropyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a phenyl group, a methoxyphenyl group, a cyanophenyl group, a phenethyl group, a thienylethyl group, an N-methylpyrazolylmethyl group, an allyl group, a 3-butenyl group, a 4-pentenyl group, a propargyl group, a 3-butynyl group, and a 4-pentynyl group. Among them, it is more preferably one group selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxyphenyl group, a cyanophenyl group, an N-methylpyrazolylmethyl group, a thienylethyl group, a propargyl group, an allyl group, and a 3-butenyl group.

[0152] In the fluorine-containing ether compound represented by formula (1), z represents 1 or 2. Since z in the fluorine-containing ether compound represented by formula (1) is 1 or 2, R 2 The number of PFPE chains (z+1) shown is 2 or 3, which is consistent with R 2 Compared with the compound having 1 PFPE chain, the compound has good hydrophobicity. Therefore, even if the thickness is thin, a lubricating layer with good corrosion inhibition effect on the magnetic recording medium can be formed. In addition, since z is 1 or 2, the compound configured in R 2 R 3 The number of becomes 1 or 2. Therefore, -R in formula (1) 2 [-CH2-R 3 -CH2-R 2 ] z - The number of polar groups possessed becomes appropriate, for example, a lubricating layer having good adhesion to the protective layer can be formed compared with the case where z is 0. In addition, the fluorinated ether compound represented by formula (1) can prevent the interaction between polar groups in the molecule, for example, compared with the case where z is 3 or more, and the polar groups possessed by the fluorinated ether compound are less likely to aggregate with each other.

[0153] (R 2 PFPE chain shown)

[0154] In the fluorine-containing ether compound represented by formula (1), (z+1) R 2 Each independently represents a perfluoropolyether chain. When a lubricant comprising the fluorinated ether compound of this embodiment is applied onto the protective layer to form a lubricating layer, R 2 The PFPE chains shown cover the surface of the protective layer and impart lubricity to the lubricating layer, thereby reducing the friction between the magnetic head and the protective layer. 2 The PFPE chain shown is appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, etc.

[0155] In the fluorine-containing ether compound represented by formula (1), (z+1) R 2 Some or all of them may be the same, or they may be different. (z+1) R 2 It is preferable that all of them are the same because the coating state of the protective layer with the fluorinated ether compound becomes uniform, and a lubricating layer having better adhesion is obtained.

[0156] So-called (z+1) R 2 Two or more R 2 The same means (z+1) R 2 Among them, the repeating units containing two or more PFPE chains have the same structure R 2 . In the same R 2 The case where the repeating units have the same structure but different average polymerization degrees is also included.

[0157] As R 2 The PFPE chain shown in the figure may be a PFPE chain formed by a polymer or copolymer of a perfluoroalkylene oxide compound, etc. Examples of the perfluoroalkylene oxide compound include perfluoromethylene oxide compounds, perfluoroethylene oxide compounds, perfluoro-n-propylene oxide compounds, perfluoro-isopropylene oxide compounds, and perfluorobutylene oxide compounds.

[0158] The two or three R in formula (1) 2 Preferably, each of the PFPE chains independently is a polymer or copolymer derived from a perfluoroalkylene oxide compound and represented by the following formula (9).

[0159] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(9)

[0160] (In formula (9), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20. However, w2, w3, w4, and w5 are not all 0 at the same time. w1 and w6 represent average values ​​of the number of CF2, and each independently represents 1 to 3. There is no particular limitation on the order of arrangement of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) as repeating units in formula (9).)

[0161] In formula (9), w2, w3, w4, and w5 represent average polymerization degrees, and are each independently 0 to 20, preferably 0 to 15, and more preferably 0 to 10.

[0162] In formula (9), w1 and w6 are average values ​​representing the number of CF2, and each independently represents 1 to 3. In the PFPE chain represented by formula (9), w1 and w6 are determined by the structure of the repeating unit arranged at the end of the chain structure, etc.

[0163] In formula (9), (CF2O), (CF2CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) are repeating units. There is no particular restriction on the arrangement order of the repeating units in formula (9). In addition, there is no particular restriction on the number of types of repeating units in formula (9).

[0164] The two or three R in formula (1) 2 Preferably, each independently is any one selected from the group consisting of PFPE chains represented by the following formulae (10-1) to (10-4).

[0165] If the (z+1) R in formula (1) 2 Each of the PFPE chains represented by formulas (10-1) to (10-4) is a fluorine-containing ether compound that can provide a lubricating layer having good lubricity. 2 When each is any one of the PFPE chains represented by formulas (10-1) to (10-4), the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) in the PFPE chain to the number of carbon atoms is appropriate. Therefore, a fluorinated ether compound having a moderate hardness is obtained. Therefore, the fluorinated ether compound applied on the protective layer is not easy to agglomerate on the protective layer, and a lubricating layer with a thinner thickness can be formed with a sufficient coverage. In addition, the fluorinated ether compound has moderate softness, so that a lubricating layer with better pickup and shedding characteristics can be formed.

[0166] -CF2-(OCF2CF2) l -(OCF2) m -OCF2-(10-1)

[0167] (In formula (10-1), l and m represent average polymerization degrees, l represents 0.1 to 20, and m represents 0 to 20.)

[0168] -CF2CF2-(OCF2CF2CF2) n -OCF2CF2-(10-2)

[0169] (In formula (10-2), n represents an average degree of polymerization and is 0.1 to 15.)

[0170] -CF2CF2CF2-(OCF2CF2CF2CF2) o-OCF2CF2CF2-(10-3)

[0171] (In formula (10-3), o represents an average degree of polymerization and is 0.1 to 10.)

[0172] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(10-4)

[0173] (In formula (10-4), w8 and w9 represent average polymerization degrees, and each independently represents 0.1 to 20. w7 and w10 represent average values ​​of the number of CF2, and each independently represents 1 to 2.)

[0174] In formula (10-1), there is no particular restriction on the arrangement order of (OCF2CF2) and (OCF2) as repeating units. In formula (10-1), the number l of (OCF2CF2) and the number m of (OCF2) may be the same or different. The PFPE chain shown in formula (10-1) may be a polymer of (OCF2CF2). In addition, the PFPE chain shown in formula (10-1) may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF2CF2) and (OCF2).

[0175] In formulas (10-1) to (10-3), since l, which represents the average degree of polymerization, is 0.1 to 20, m is 0 to 20, n is 0.1 to 15, and o is 0.1 to 10, it is a fluorine-containing ether compound that can obtain a lubricating layer with good lubricity. In addition, in formulas (10-1) to (10-3), since l and m, which represent the average degree of polymerization, are 20 or less, n is 15 or less, and o is 10 or less, the viscosity of the fluorine-containing ether compound is not too high, and a lubricant containing the fluorine-containing ether compound is easy to apply, which is preferred. In order to obtain a fluorine-containing ether compound that is easy to wet and spread on the protective layer and easy to obtain a lubricating layer with a uniform film thickness, l, m, n, and o, which represent the average degree of polymerization, are preferably 1 to 10, more preferably 1.5 to 8, and further preferably 2 to 7.

[0176] In formula (10-4), there is no particular restriction on the arrangement order of (CF2CF2CF2O) and (CF2CF2O) as repeating units. In formula (10-4), the number w8 of (CF2CF2CF2O) and the number w9 of (CF2CF2O) representing the average degree of polymerization may be the same or different. Formula (10-4) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF2CF2CF2O) and (CF2CF2O).

[0177] In formula (10-4), w8 and w9, which represent the average degree of polymerization, are each independently 0.1 to 20, preferably 1 to 15, and more preferably 1 to 10.

[0178] w7 and w10 in formula (10-4) are average values ​​representing the number of CF2, and each independently represents 1 to 2. w7 and w10 are determined by the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (10-4).

[0179] (R 3 The divalent linking group shown

[0180] In the fluorinated ether compound represented by formula (1), one or two R 3 is a divalent linking group represented by the above formula (5). The dotted line bonded to the oxygen atom on the left side in formula (5) represents the bond with R 1 The dotted line that is bonded to the methylene on the right side indicates the bond with R 4 When z in formula (1) is 1, R 3 Configured in 2 R 2 In the case where z is 2, the two R 3 They are configured in R 1 Side R 2 With the central R 2 Between, and R 4 Side R 2 With the central R 2 between.

[0181] R 3 is a divalent linking group having a secondary hydroxyl group. 3 It has good adhesion to the protective layer due to the secondary hydroxyl group. 3 Suppression configuration in R 3 The R at both ends 2 The PFPE chains shown are too far away from the protective layer, properly maintained with R 2 The distance between the good hydrophobic lubricating layer and the magnetic head. That is, R 3 This contributes to forming a lubricating layer with a sufficient coverage rate that is effective in suppressing corrosion of the magnetic recording medium.

[0182] In formula (5), y1 is an integer of 1 to 3, and y2 is an integer of 1 to 3. At least one of y1 and y2 is preferably 1. It is preferred that at least one of y1 and y2 is 1 because the production becomes easy. In order to maintain the flexibility of the entire linking group, it is more preferred that y1 is 1 and y2 is 1.

[0183] When z in formula (1) is 2, the two R 3 They can be the same or different. 3 The same, then the coating state of the protective layer by the fluorine-containing ether compound becomes more uniform, and a lubricating layer with better adhesion can be formed. 3 In the same case, the fluorine-containing ether compound is easy to produce and is therefore preferred.

[0184] The so-called "two Rs" 3 Same” means two R 3 The atoms contained in the R 2 That is, when z is 2, the fluorine-containing ether compound represented by formula (1) preferably has two R 3 In the formula (5), y1 and y2 are relative to R arranged in the center of the chain structure. 2 The fluorine-containing ether compound has a symmetrical value. 1 Side R 3 In formula (5), y1 is 1, y2 is 2, and R 4 Side R 3 When y1 is 2 and y2 is 1 in formula (5), the two R 3 In addition, for example, in R 1 Side R 3 In formula (5), y1 is 2, y2 is 1, and R 4 Side R 3 When y1 is 1 and y2 is 2 in formula (5), the two R 3 same.

[0185] In the fluorine-containing ether compound represented by formula (1), it is preferred that R 1 -[B]-[A]-, and -[C]-[D]-R 4 The same, so in -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] z The atoms are arranged symmetrically on both sides of the structure represented by -CH2-. In this case, the production is easy, so the production cost becomes low.

[0186] In formula (1), when z is 1, R is more preferably 1 -[B]-[A]-and-[C]-[D]-R 4 Same, and 2 R 2 This is because it is a fluorine-containing ether compound that is easy to synthesize.

[0187] In formula (1), when z is 2, R is more preferably 1 -[B]-[A]-and-[C]-[D]-R 4 Same, and 3 R 2 This is because it is a fluorine-containing ether compound that is easy to synthesize. Further, when z is 2, preferably 2 R 3 The atoms contained in the R 2 This is because it is a fluorine-containing ether compound that is easier to synthesize.

[0188] Specifically, the fluorine-containing ether compound represented by the formula (1) is preferably a compound represented by the following formulas (1A) to (1V) and (2A) to (2V).

[0189] In the compounds represented by the following formulae (1A) to (1V) and (2A) to (2V), Rf1 and Rf2 representing the PFPE chain each have the following structure. That is, Rf1 is the PFPE chain represented by the above formula (10-1), and Rf2 is the PFPE chain represented by the above formula (10-2). In addition, l and m in Rf1 representing the PFPE chain in the formulae (1A) to (1V) and (2A) to (2V), and n in Rf2 are values ​​representing the average degree of polymerization and are not necessarily integers.

[0190]

[0191] (Rf21a in formula (1A) is represented by formula (1AF). In Rf21a, n1a represents an average degree of polymerization and is 0.1 to 15. n1a in two Rf21a in formula (1A) may be the same or different.)

[0192] (Rf21b in formula (1B) is represented by formula (1BF). In Rf21b, n1b represents an average degree of polymerization and is 0.1 to 15. n1b in two Rf21b in formula (1B) may be the same or different.)

[0193]

[0194] (Rf11c in formula (1C) is represented by formula (1CF). In Rf11c, l1c and m1c represent average polymerization degrees, l1c represents 0.1 to 20, and m1c represents 0 to 20. l1c and m1c in two Rf11c in formula (1C) may be the same or different.)

[0195] (Rf11d in formula (1D) is represented by formula (1DF). In Rf11d, l1d and m1d represent average polymerization degrees, l1d represents 0.1 to 20, and m1d represents 0 to 20. l1d and m1d in two Rf11d in formula (1D) may be the same or different.)

[0196]

[0197] (Rf21e in formula (1E) is represented by formula (1EF). In Rf21e, n1e represents an average degree of polymerization and is 0.1 to 15. n1e in two Rf21e in formula (1E) may be the same or different.)

[0198] (Rf21f in formula (1F) is represented by formula (1FF). In Rf21f, n1f represents an average degree of polymerization and is 0.1 to 15. n1f in two Rf21f in formula (1F) may be the same or different.)

[0199]

[0200] (Rf21g in formula (1G) is represented by formula (1GF). In Rf21g, n1g represents an average degree of polymerization and is 0.1 to 15. n1g in two Rf21g in formula (1G) may be the same or different.)

[0201] (Rf11h in formula (1H) is represented by formula (1HF). In Rf11h, l1h and m1h represent average polymerization degrees, l1h represents 0.1 to 20, and m1h represents 0 to 20. l1h and m1h in two Rf11h in formula (1H) may be the same or different.)

[0202]

[0203] (Rf11i in formula (1I) is represented by formula (1IF). In Rf11i, l1i and m1i represent average polymerization degrees, l1i represents 0.1 to 20, and m1i represents 0 to 20. l1i and m1i in two Rf11i in formula (1I) may be the same or different.)

[0204] (Rf21j in formula (1J) is represented by formula (1JF). In Rf21j, n1j represents an average degree of polymerization and is 0.1 to 15. n1j in two Rf21j in formula (1J) may be the same or different.)

[0205]

[0206] (Rf11k in formula (1K) is represented by formula (1KF). In Rf11k, l1k and m1k represent average polymerization degrees, l1k represents 0.1 to 20, and m1k represents 0 to 20. l1k and m1k in two Rf11k in formula (1K) may be the same or different.)

[0207] (Rf211 in formula (1L) is represented by formula (1LF). In Rf211, n11 represents an average degree of polymerization and is 0.1 to 15. n11 in two Rf211 in formula (1L) may be the same or different.)

[0208]

[0209] (Rf21m in formula (1M) is represented by formula (1MF). In Rf21m, n1m represents an average degree of polymerization and is 0.1 to 15. n1m in two Rf21m in formula (1M) may be the same or different.)

[0210] (Rf21n in formula (1N) is represented by formula (1NF). In Rf21n, n1n represents an average degree of polymerization and is 0.1 to 15. n1n in two Rf21n in formula (1N) may be the same or different.)

[0211]

[0212] (Rf21o in formula (1O) is represented by formula (1OF). In Rf21o, n1o represents an average degree of polymerization and is 0.1 to 15. n1o in two Rf21o in formula (1O) may be the same or different.)

[0213] (Rf21p in formula (1P) is represented by formula (1PF). In Rf21p, n1p represents an average degree of polymerization and is 0.1 to 15. n1p in two Rf21p in formula (1P) may be the same or different.)

[0214]

[0215] (Rf11q in formula (1Q) is represented by formula (1QF). In Rf11q, l1q and m1q represent average polymerization degrees, l1q represents 0.1 to 20, and m1q represents 0 to 20. l1q and m1q in two Rf11q in formula (1Q) may be the same or different.)

[0216] (Rf11r in formula (1R) is represented by formula (1RF). In Rf11r, l1r and m1r represent average polymerization degrees, l1r represents 0.1 to 20, and m1r represents 0 to 20. l1r and m1r in two Rf11r in formula (1R) may be the same or different.)

[0217]

[0218] (Rf11s in formula (1S) is represented by formula (1SF). In Rf11s, l1s and m1s represent average polymerization degrees, l1s represents 0.1 to 20, and m1s represents 0 to 20. l1s and m1s in two Rf11s in formula (1S) may be the same or different.)

[0219] (Rf11t in formula (1T) is represented by formula (1TF). In Rf11t, l1t and m1t represent average polymerization degrees, l1t represents 0.1 to 20, and m1t represents 0 to 20. l1t and m1t in two Rf11t in formula (1T) may be the same or different.)

[0220]

[0221] (Rf21u in formula (1U) is represented by formula (1UF). In Rf21u, n1u represents an average degree of polymerization and is 0.1 to 15. n1u in two Rf21u in formula (1U) may be the same or different.)

[0222] (Rf21v in formula (1V) is represented by formula (1VF). In Rf21v, n1v represents an average degree of polymerization and is 0.1 to 15. n1v in two Rf21v in formula (1V) may be the same or different.)

[0223]

[0224] (Rf22a in formula (2A) is represented by formula (2AF). In Rf22a, n2a represents an average degree of polymerization and is 0.1 to 15. The n2a in the three Rf22a in formula (2A) may be different from each other or may be partially or entirely the same.)

[0225] (Rf22b in formula (2B) is represented by formula (2BF). In Rf22b, n2b represents an average degree of polymerization and is 0.1 to 15. The n2b in the three Rf22b in formula (2B) may be different from each other, or may be partially or entirely the same.)

[0226]

[0227] (Rf12c in formula (2C) is represented by formula (2CF). In Rf12c, l2c and m2c represent average polymerization degrees, l2c represents 0.1 to 20, and m2c represents 0 to 20. l2c and m2c in the three Rf12c in formula (2C) may be different from each other, or may be partially or entirely the same.)

[0228] (Rf12d in formula (2D) is represented by formula (2DF). In Rf12d, l2d and m2d represent average polymerization degrees, l2d represents 0.1 to 20, and m2d represents 0 to 20. l2d and m2d in the three Rf12d in formula (2D) may be different from each other, or may be partially or entirely the same.)

[0229]

[0230] (Rf22e in formula (2E) is represented by formula (2EF). In Rf22e, n2e represents an average degree of polymerization and is 0.1 to 15. The n2e in the three Rf22e in formula (2E) may be different from each other or may be partially or entirely the same.)

[0231] (Rf22f in formula (2F) is represented by formula (2FF). In Rf22f, n2f represents an average degree of polymerization and is 0.1 to 15. The n2f in the three Rf22f in formula (2F) may be different from each other, or may be partially or entirely the same.)

[0232]

[0233] (Rf22g in formula (2G) is represented by formula (2GF). In Rf22g, n2g represents an average degree of polymerization and is 0.1 to 15. The n2g in the three Rf22g in formula (2G) may be different from each other, or may be partially or entirely the same.)

[0234] (Rf12h in formula (2H) is represented by formula (2HF). In Rf12h, l2h and m2h represent average polymerization degrees, l2h represents 0.1 to 20, and m2h represents 0 to 20. l2h and m2h in the three Rf12h in formula (2H) may be different from each other, or may be partially or entirely the same.)

[0235]

[0236] (Rf12i in formula (2I) is represented by formula (2IF). In Rf12i, l2i and m2i represent average polymerization degrees, l2i represents 0.1 to 20, and m2i represents 0 to 20. l2i and m2i in the three Rf12i in formula (2I) may be different from each other, or may be partially or entirely the same.)

[0237] (Rf22j in formula (2J) is represented by formula (2JF). In Rf22j, n2j represents an average degree of polymerization and is 0.1 to 15. The n2j in the three Rf22j in formula (2J) may be different from each other, or may be partially or entirely the same.)

[0238]

[0239] (Rf12k in formula (2K) is represented by formula (2KF). In Rf12k, l2k and m2k represent average polymerization degrees, l2k represents 0.1 to 20, and m2k represents 0 to 20. l2k and m2k in the three Rf12k in formula (2K) may be different from each other, or may be partially or entirely the same.)

[0240] (Rf221 in formula (2L) is represented by formula (2LF). In Rf221, n21 represents an average degree of polymerization and is 0.1 to 15. The n21 in the three Rf221 in formula (2L) may be different from each other or may be partially or entirely the same.)

[0241]

[0242] (Rf22m in formula (2M) is represented by formula (2MF). In Rf22m, n2m represents an average degree of polymerization and is 0.1 to 15. The n2m in the three Rf22m in formula (2M) may be different from each other, or may be partially or entirely the same.)

[0243] (Rf22n in formula (2N) is represented by formula (2NF). In Rf22n, n2n represents an average degree of polymerization and is 0.1 to 15. The n2n in the three Rf22n in formula (2N) may be different from each other or may be partially or entirely the same.)

[0244]

[0245] (Rf22o in formula (2O) is represented by formula (2OF). In Rf22o, n2o represents the average degree of polymerization and is 0.1 to 15. The n2o in the three Rf22o in formula (2O) may be different from each other or may be partially or entirely the same.)

[0246] (Rf22p in formula (2P) is represented by formula (2PF). In Rf22p, n2p represents an average degree of polymerization and is 0.1 to 15. The n2p in the three Rf22p in formula (2P) may be different from each other, or may be partially or entirely the same.)

[0247]

[0248] (Rf12q in formula (2Q) is represented by formula (2QF). In Rf12q, l2q and m2q represent average polymerization degrees, l2q represents 0.1 to 20, and m2q represents 0 to 20. l2q and m2q in the three Rf12q in formula (2Q) may be different from each other, or may be partially or entirely the same.)

[0249] (Rf12r in formula (2R) is represented by formula (2RF). In Rf12r, l2r and m2r represent average polymerization degrees, l2r represents 0.1 to 20, and m2r represents 0 to 20. l2r and m2r in the three Rf12r in formula (2R) may be different from each other, or may be partially or entirely the same.)

[0250]

[0251] (Rf12s in formula (2S) is represented by formula (2SF). In Rf12s, l2s and m2s represent average polymerization degrees, l2s represents 0.1 to 20, and m2s represents 0 to 20. l2s and m2s in the three Rf12s in formula (2S) may be different from each other, or may be partially or entirely the same.)

[0252] (Rf12t in formula (2T) is represented by formula (2TF). In Rf12t, l2t and m2t represent average polymerization degrees, l2t represents 0.1 to 20, and m2t represents 0 to 20. l2t and m2t in the three Rf12t in formula (2T) may be different from each other, or may be partially or entirely the same.)

[0253]

[0254] (Rf22u in formula (2U) is represented by formula (2UF). In Rf22u, n2u represents an average degree of polymerization and is 0.1 to 15. The n2u in the three Rf22u in formula (2U) may be different from each other or may be partially or entirely the same.)

[0255] (Rf22v in formula (2V) is represented by formula (2VF). In Rf22v, n2v represents an average degree of polymerization and is 0.1 to 15. The n2v in the three Rf22v in formula (2V) may be different from each other, or may be partially or entirely the same.)

[0256] The fluorine-containing ether compound represented by the formula (1) is also preferably a compound represented by the following formulas (4A) to (4O) and (5A) to (5O).

[0257] In the compounds represented by the following formulas (4A) to (4O) and (5A) to (5O), Rf1 representing a PFPE chain is the PFPE chain represented by the above formula (10-1), and Rf2 is the PFPE chain represented by the above formula (10-2). In addition, l and m in Rf1 representing a PFPE chain in the formulas (4A) to (4O) and (5A) to (5O), and n in Rf2 are values ​​representing the average degree of polymerization and are not necessarily integers.

[0258]

[0259] (Rf24a in formula (4A) is represented by formula (4AF). In Rf24a, n4a represents an average degree of polymerization and is 0.1 to 15. n4a in two Rf24a in formula (4A) may be the same or different.)

[0260] (Rf24b in formula (4B) is represented by formula (4BF). In Rf24b, n4b represents an average degree of polymerization and is 0.1 to 15. n4b in two Rf24b in formula (4B) may be the same or different.)

[0261]

[0262] (Rf24c in formula (4C) is represented by formula (4CF). In Rf24c, n4c represents an average degree of polymerization and is 0.1 to 15. n4c in two Rf24c in formula (4C) may be the same or different.)

[0263] (Rf24d in formula (4D) is represented by formula (4DF). In Rf24d, n4d represents an average degree of polymerization and is 0.1 to 15. n4d in two Rf24d in formula (4D) may be the same or different.)

[0264]

[0265] (Rf24e in formula (4E) is represented by formula (4EF). In Rf24e, n4e represents an average degree of polymerization and is 0.1 to 15. n4e in two Rf24e in formula (4E) may be the same or different.)

[0266] (Rf24f in formula (4F) is represented by formula (4FF). In Rf24f, n4f represents an average degree of polymerization and is 0.1 to 15. n4f in two Rf24f in formula (4F) may be the same or different.)

[0267]

[0268] (Rf24g in formula (4G) is represented by formula (4GF). In Rf24g, n4g represents an average degree of polymerization and is 0.1 to 15. n4g in two Rf24g in formula (4G) may be the same or different.)

[0269] (Rf24h in formula (4H) is represented by formula (4HF). In Rf24h, n4h represents an average degree of polymerization and is 0.1 to 15. n4h in two Rf24h in formula (4H) may be the same or different.)

[0270]

[0271] (Rf24i in formula (4I) is represented by formula (4IF). In Rf24i, n4i represents an average degree of polymerization and is 0.1 to 15. n4i in two Rf24i in formula (4I) may be the same or different.)

[0272] (Rf24j in formula (4J) is represented by formula (4JF). In Rf24j, n4j represents an average degree of polymerization and is 0.1 to 15. n4j in two Rf24j in formula (4J) may be the same or different.)

[0273]

[0274] (Rf24k in formula (4K) is represented by formula (4KF). Me represents a methyl group. In Rf24k, n4k represents an average degree of polymerization and is 0.1 to 15. n4k in two Rf24k in formula (4K) may be the same or different.)

[0275] (Rf241 in formula (4L) is represented by formula (4LF). In Rf241, n41 represents an average degree of polymerization and is 0.1 to 15. n41 in two Rf241 in formula (4L) may be the same or different.)

[0276]

[0277] (Rf24m in formula (4M) is represented by formula (4MF). In Rf24m, n4m represents an average degree of polymerization and is 0.1 to 15. n4m in two Rf24m in formula (4M) may be the same or different.)

[0278] (Rf24n in formula (4N) is represented by formula (4NF). In Rf24n, n4n represents an average degree of polymerization and is 0.1 to 15. n4n in two Rf24n in formula (4N) may be the same or different.)

[0279]

[0280] (Rf24o in formula (4O) is represented by formula (4OF). In Rf24o, n4o represents an average degree of polymerization, which is 0.1 to 15. n4o in two Rf24o in formula (4O) may be the same or different.)

[0281] (Rf25a in formula (5A) is represented by formula (5AF). In Rf25a, n5a represents an average degree of polymerization and is 0.1 to 15. The n5a in the three Rf25a in formula (5A) may be different from each other, or may be partially or entirely the same.)

[0282]

[0283] (Rf25b in formula (5B) is represented by formula (5BF). In Rf25b, n5b represents an average degree of polymerization and is 0.1 to 15. The n5b in the three Rf25b in formula (5B) may be different from each other, or may be partially or entirely the same.)

[0284] (Rf25c in formula (5C) is represented by formula (5CF). In Rf25c, n5c represents an average degree of polymerization, which is 0.1 to 15. The n5c in the three Rf25c in formula (5C) may be different from each other, or may be partially or entirely the same.)

[0285]

[0286] (Rf25d in formula (5D) is represented by formula (5DF). In Rf25d, n5d represents an average degree of polymerization and is 0.1 to 15. The n5d in the three Rf25d in formula (5D) may be different from each other, or may be partially or entirely the same.)

[0287] (Rf25e in formula (5E) is represented by formula (5EF). In Rf25e, n5e represents an average degree of polymerization and is 0.1 to 15. The n5e in the three Rf25e in formula (5E) may be different from each other, or may be partially or entirely the same.)

[0288]

[0289] (Rf25f in formula (5F) is represented by formula (5FF). In Rf25f, n5f represents an average degree of polymerization and is 0.1 to 15. The n5f in the three Rf25f in formula (5F) may be different from each other, or may be partially or entirely the same.)

[0290] (Rf25g in formula (5G) is represented by formula (5GF). In Rf25g, n5g represents an average degree of polymerization and is 0.1 to 15. The n5g in the three Rf25g in formula (5G) may be different from each other, or may be partially or entirely the same.)

[0291]

[0292] (Rf25h in formula (5H) is represented by formula (5HF). In Rf25h, n5h represents an average degree of polymerization and is 0.1 to 15. The n5h in the three Rf25h in formula (5H) may be different from each other, or may be partially or entirely the same.)

[0293] (Rf25i in formula (5I) is represented by formula (5IF). In Rf25i, n5i represents an average degree of polymerization and is 0.1 to 15. The n5i in the three Rf25i in formula (5I) may be different from each other, or may be partially or entirely the same.)

[0294]

[0295] (Rf25j in formula (5J) is represented by formula (5JF). In Rf25j, n5j represents an average degree of polymerization and is 0.1 to 15. The n5j in the three Rf25j in formula (5J) may be different from each other, or may be partially or entirely the same.)

[0296] (Rf25k in formula (5K) is represented by formula (5KF). Me represents a methyl group. In Rf25k, n5k represents an average degree of polymerization and is 0.1 to 15. The n5k in the three Rf25k in formula (5K) may be different from each other, or may be partially or entirely the same.)

[0297]

[0298] (Rf251 in formula (5L) is represented by formula (5LF). In Rf251, n51 represents an average degree of polymerization and is 0.1 to 15. The n51 in the three Rf251 in formula (5L) may be different from each other or may be partially or entirely the same.)

[0299] (Rf25m in formula (5M) is represented by formula (5MF). In Rf25m, n5m represents the average degree of polymerization and is 0.1 to 15. The n5m in the three Rf25m in formula (5M) may be different from each other, or may be partially or entirely the same.)

[0300]

[0301] (Rf25n in formula (5N) is represented by formula (5NF). In Rf25n, n5n represents an average degree of polymerization and is 0.1 to 15. The n5n in the three Rf25n in formula (5N) may be different from each other or may be partially or entirely the same.)

[0302] (Rf25o in formula (5O) is represented by formula (5OF). In Rf25o, n5o represents the average degree of polymerization and is 0.1 to 15. The n5o in the three Rf25o in formula (5O) may be different from each other or may be partially or entirely the same.)

[0303] When the above equations (4A) to (4O) and (5A) to (5O) are applied to equation (1), the value of z, R 1 , [A], [B], R 2 , R 3 , [C], [D], R 4 The structures are shown in Tables 1 to 4.

[0304] Table 1

[0305]

[0306] Table 2

[0307]

[0308] Table 3

[0309]

[0310] Table 4

[0311]

[0312] If the fluorine-containing ether compound represented by formula (1) is a compound represented by any one of the above formulas (1A) to (1V), (2A) to (2V), (4A) to (4O), and (5A) to (5O), a lubricating layer can be formed that has a good effect of inhibiting corrosion of the magnetic recording medium even if the thickness is thin, and can inhibit pickup and shedding, which is preferred.

[0313] The number average molecular weight (Mn) of the fluorinated ether compound of the present embodiment is preferably in the range of 500 to 10,000, and particularly preferably in the range of 600 to 5,000. If the number average molecular weight is 500 or more, the lubricating layer formed by the lubricant containing the fluorinated ether compound of the present embodiment has excellent heat resistance. The number average molecular weight of the fluorinated ether compound is more preferably 600 or more. In addition, if the number average molecular weight is 10,000 or less, the viscosity of the fluorinated ether compound becomes appropriate, and a lubricating layer with a thin film thickness can be easily formed by applying the lubricant containing the fluorinated ether compound. In order to achieve a viscosity that is easy to handle when applied to a lubricant, the number average molecular weight of the fluorinated ether compound is more preferably 5,000 or less.

[0314] The number average molecular weight (Mn) of the fluorinated ether compound was determined by using AVANCE III 400 manufactured by Bruker Biospin Co., Ltd. 1 H-NMR and 19 Specifically, the value measured by F-NMR. 19 The number of repeating units of the PFPE chain was calculated from the integrated value measured by F-NMR to determine the number average molecular weight. In the measurement of NMR (nuclear magnetic resonance), the sample was diluted in a hexafluorobenzene / d-acetone (4 / 1 v / v) solvent for measurement. 19 The standard for the F-NMR chemical shift was the peak of hexafluorobenzene at -164.7 ppm. 1 The standard of H-NMR chemical shift was set at 2.2 ppm based on the peak of acetone.

[0315] The fluorine-containing ether compound of the present embodiment is preferably subjected to molecular weight fractionation by an appropriate method so that the molecular weight distribution (ratio of weight average molecular weight (Mw) / number average molecular weight (Mn)) is 1.3 or less.

[0316] In the present embodiment, the method for molecular weight fractionation is not particularly limited, and for example, molecular weight fractionation using silica gel column chromatography, gel permeation chromatography (GPC), or the like, molecular weight fractionation using supercritical extraction, or the like can be used.

[0317] Here, the reason why when a lubricant layer is formed on a protective layer of a magnetic recording medium using a lubricant containing a fluorinated ether compound of this embodiment, a lubricant layer that is thin but effective in suppressing corrosion of the magnetic recording medium and can suppress pickup and peeling can be formed is described.

[0318] In the fluorinated ether compound of the present embodiment represented by formula (1), [A], [B], [C] and [D] are each a divalent linking group having a secondary hydroxyl group. Furthermore, in the fluorinated ether compound of the present embodiment, a -[B]-[A]- structure (hereinafter, sometimes abbreviated as "BA structure") containing 1 to 3 secondary hydroxyl groups and a -[C]-[D]- structure (hereinafter, sometimes abbreviated as "CD structure") containing 1 to 2 secondary hydroxyl groups are respectively well-balancedly arranged in -R via a methylene group (-CH2-). 2 [-CH2-R 3 -CH2-R 2 ] z - at both ends. Furthermore, the etheric oxygen atoms in the BA structure and the CD structure impart appropriate flexibility to the molecular structure of the fluorine-containing ether compound represented by the formula (1).

[0319] In addition, when the BA structure and / or the CD structure includes a plurality of secondary hydroxyl groups, the carbon atoms to which the secondary hydroxyl groups are bonded are bonded to each other via a linking group consisting of a methylene group (-CH2-) and an ether bond (-O-). Therefore, when the BA structure and / or the CD structure has a plurality of secondary hydroxyl groups, the distance between adjacent secondary hydroxyl groups also becomes appropriate, and it is considered that each secondary hydroxyl group is easily adsorbed to the protective layer.

[0320] From these facts, when the lubricating layer containing the fluorine-containing ether compound of the present embodiment is formed on the protective layer, the secondary hydroxyl groups contained in the BA structure and the secondary hydroxyl groups contained in the CD structure effectively participate in bonding with the active sites on the protective layer.

[0321] In addition, R in formula (1) 4 It is a branched terminal group containing two or three primary hydroxyl groups. The primary hydroxyl group has less steric hindrance than the secondary hydroxyl group and the tertiary hydroxyl group, and therefore effectively participates in the formation of intermolecular hydrogen bonds between the fluorinated ether compounds.

[0322] Thus, in the fluorine-containing ether compound of the present embodiment represented by formula (1), <1> the secondary hydroxyl groups included in the BA structure and the secondary hydroxyl groups included in the CD structure effectively participate in the bonding with the active sites on the protective layer, and <2> R 4 The contained plurality of primary hydroxyl groups participate in the formation of hydrogen bonds between molecules of the fluorine-containing ether compound.

[0323] Therefore, in the lubricating layer containing the fluorine-containing ether compound of the present embodiment, -R 2 [-CH2-R 3 -CH2-R 2 ] z-The excellent adsorption force to the protective layer exhibited by the secondary hydroxyl groups at both ends of the - and the excellent intermolecular force exhibited by the primary hydroxyl groups of the branched terminal groups effectively function in a well-balanced manner.

[0324] Furthermore, for the lubricating layer comprising the fluorinated ether compound of this embodiment, <3> a lubricating layer comprising R in the formula (1) can be obtained. 2 The 2 or 3 PFPE chains shown above provide sufficient hydrophobicity and can be placed in adjacent R 2 The secondary hydroxyl group R 3 To inhibit R 2 Too far away from the protective layer.

[0325] In this way, the lubricating layer comprising the fluorinated ether compound of the present embodiment has the functions of <1> to <3> described above, and through the synergistic effect of these functions, the adhesion to the protective layer and the effect of inhibiting the corrosion of the magnetic recording medium are fully obtained. As a result, the magnetic recording medium having a lubricating layer comprising the fluorinated ether compound of the present embodiment can prevent the fluorinated ether compound that does not adhere to the protective layer (adsorbed) from being attached to the magnetic head as a foreign matter (stain), thereby inhibiting pickup. In addition, the magnetic recording medium inhibits the shedding of the lubricating layer due to the centrifugal force and / or heat caused by high-speed rotation, which causes the lubricant to scatter / evaporate and the film thickness of the lubricating layer to be reduced. Furthermore, the magnetic recording medium has excellent corrosion resistance, and is reliable and durable.

[0326] "Manufacturing method"

[0327] The method for producing the fluorine-containing ether compound of the present embodiment is not particularly limited, and the fluorine-containing ether compound of the present embodiment can be produced by a conventionally known production method. The fluorine-containing ether compound of the present embodiment can be produced by, for example, the production method described below.

[0328] [First manufacturing method (when z is 1)]

[0329] (R 1 -[B]-[A]-and-[C]-[D]-R 4 Same, 2 R 2 Same situation)

[0330] First, prepare the R 2 The corresponding PFPE chain has a fluorine compound with a hydroxymethyl group (-CH2OH) at both ends. Next, the hydroxyl group of the hydroxymethyl group at one end of the fluorine compound is connected to the R 1 -[B]-[A]-(=-[C]-[D]-R 4 ) is reacted with an epoxy compound corresponding to the group consisting of (first reaction). Thus, a 2One end of the corresponding PFPE chain has 1 -[B]-[A]-(=-[C]-[D]-R 4 ) is an intermediate compound 1-1 of a group corresponding to the above.

[0331] In the first reaction, the compound having the same structure as R can be protected by using an appropriate protecting group. 1 -[B]-[A]-(=-[C]-[D]-R 4 ) is reacted with the hydroxyl group possessed by the epoxy compound corresponding to the group composed of ) and then reacted with the above-mentioned fluorine-based compound.

[0332] The fluorinated ether compound used in the production of this embodiment is 1 -[B]-[A]-(or -[C]-[D]-R 4 The epoxy compound corresponding to the group consisting of ) can be synthesized or purchased from the market and used.

[0333] When synthesizing the above-mentioned epoxy compound, for example, a fluorine-containing ether compound having the same R as that of the fluorine-containing ether compound to be produced can be used. 1 -[B]-[A]-(or -[C]-[D]-R 4 ) and a compound having an epoxy group. In this method, as the compound having an epoxy group, for example, any compound selected from epichlorohydrin, epibromohydrin, 2-bromoethyl oxirane, and allyl glycidyl ether can be used. In addition, as another method for synthesizing the above-mentioned epoxy compound, a fluorine-containing ether compound having an R corresponding to the structure of the group to be produced can be used. 1 -[B]-[A]-(or -[C]-[D]-R 4 ) is an unsaturated compound having a structure corresponding to a group composed of, and its unsaturated bond is oxidized.

[0334] Next, the hydroxyl group of the hydroxymethyl group disposed at the terminal of the intermediate compound 1-1 is reacted with a 3 The halogen compound of the corresponding epoxy group is reacted. Furthermore, the hydroxyl group disposed at the terminal of another molecule of the intermediate compound 1-1 is further reacted with the obtained epoxy compound (second reaction).

[0335] As with the above R 3 The corresponding epoxy halogen compounds, for example, in R 3 In the case where both y1 and y2 in the formula (5) are 1, epibromohydrin can be used.

[0336] By performing the above steps, it is possible to produce a compound wherein z in formula (1) is 1 and R 1 -[B]-[A]-and-[C]-[D]-R4 The same, and R 2 The two PFPE chains shown are identical compounds.

[0337] (R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or 2 R 2 Different situations)

[0338] In the first reaction of the first production method, 1 -[B]-[A]-and-[C]-[D]-R 4 The same, and R 2 The same operation was performed as in the case of the compound with two identical PFPE chains as shown in FIG. 1 Side R 2 One end of the corresponding PFPE chain has 1 The group corresponding to -[B]-[A]- is an intermediate compound 1-2 in which a hydroxymethyl group is arranged at the other end.

[0339] Furthermore, in R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or R 2 In the case of the two PFPE chains shown, in the first reaction, one end of the PFPE chain has a 1 -[B]-[A]- corresponding intermediate compound 1-2 is prepared in the same manner as in R 4 Side R 2 One end of the corresponding PFPE chain has a -[C]-[D]-R 4 The corresponding group is an intermediate compound 1-3 having a hydroxymethyl group at the other end.

[0340] Then, the intermediate compound 1-2 and the compound having R 3 The corresponding halogen compound of the epoxy group is reacted to obtain an epoxy compound. Next, the intermediate compound 1-3 is reacted with the obtained epoxy compound (second reaction).

[0341] In the second reaction, the intermediate compound 1-2 is reacted with a 3 The case where an epoxy compound obtained by reacting a halogen compound having a corresponding epoxy group with the intermediate compound 1-3 is described as an example, but the intermediate compound 1-3 can also be reacted with a halogen compound having R 3 The epoxy compound obtained by reacting the corresponding epoxy group-containing halogen compound is reacted with the intermediate compound 1-2.

[0342] By performing the above steps, it is possible to produce a compound wherein z in formula (1) is 1 and R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or R 2 The two PFPE chains shown are different compounds.

[0343] [Second manufacturing method (when z is 2)]

[0344] (R 1 -[B]-[A]-and-[C]-[D]-R 4 Same, 2 R 3 Same, 3 Rs 2 Same situation)

[0345] First, prepare the R 2 The corresponding PFPE chain has a fluorine compound having a hydroxymethyl group (-CH2OH) at both ends. Next, the hydroxyl groups of the hydroxymethyl groups at both ends of the fluorine compound are connected to a fluorine compound having a 3 The corresponding epoxy group is reacted with a halogen compound (first reaction). 2 The two ends of the corresponding PFPE chain have 3 The corresponding epoxy intermediate compound 2-1.

[0346] In addition, prepare the R 2 The corresponding PFPE chain has a fluorine compound having a hydroxymethyl group (-CH2OH) at both ends. Furthermore, the hydroxyl group of the hydroxymethyl group at one end of the fluorine compound is connected to R in formula (1). 1 -[B]-[A]-(=-[C]-[D]-R 4 ) is reacted with an epoxy compound corresponding to the group consisting of (second reaction). Thus, a 2 One end of the corresponding PFPE chain has 1 -[B]-[A]-(=-[C]-[D]-R 4 ) and an intermediate compound 2-2 having a hydroxymethyl group at the other end.

[0347] In the second reaction, the residue with R can be protected by using an appropriate protecting group. 1 -[B]-[A]-(=-[C]-[D]-R 4 ) is reacted with the hydroxyl group possessed by the epoxy compound corresponding to the group composed of ) and then reacted with the above-mentioned fluorine-based compound.

[0348] In addition, the second reaction in the second production method may be performed after the first reaction or before the first reaction.

[0349] Then, the hydroxyl group of the hydroxymethyl group disposed at one terminal of the intermediate compound 2-2 is reacted with the epoxy groups disposed at both terminals of the intermediate compound 2-1 (third reaction).

[0350] By carrying out the above steps, it is possible to produce a compound wherein z in formula (1) is 2 and R 3 The two linkers shown are identical and R 1 -[B]-[A]-and-[C]-[D]-R 4 The same, and R 2 The three PFPE chains shown are identical compounds.

[0351] (2 R 3 Same, R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or 3 R's 2 Any one or more of the following situations)

[0352] In the first reaction of the second production method, R 2 The two ends of the corresponding PFPE chain have 3 The corresponding epoxy intermediate compound 2-1.

[0353] Next, in the second reaction, the following intermediate compound 2-2a and intermediate compound 2-2b were synthesized in the same manner as in the intermediate compound 2-2.

[0354] Specifically, prepare 1 Side R 2 The corresponding PFPE chain has a fluorochemical compound with a hydroxymethyl group at both ends. Furthermore, the hydroxyl group of the hydroxymethyl group at one end of the fluorochemical compound is connected to the R 1 -[B]-[A]- corresponding epoxy compound of the group. Thus, the 1 Side R 2 One end of the corresponding PFPE chain has 1 The group corresponding to -[B]-[A]- is an intermediate compound 2-2a having a hydroxymethyl group at the other end.

[0355] In addition, prepare 4 Side R 2 The corresponding PFPE chain has a fluorochemical compound with a hydroxymethyl group at both ends. Furthermore, the hydroxyl group of the hydroxymethyl group at one end of the fluorochemical compound is connected to the -[C]-[D]-R 4The epoxy compound corresponding to the group consisting of 4 Side R 2 One end of the corresponding PFPE chain has a -[C]-[D]-R 4 The corresponding group is an intermediate compound 2-2b having a hydroxymethyl group at the other end.

[0356] Then, in the third reaction, the intermediate compound 2-2a and the intermediate compound 2-2b are respectively reacted with the intermediate compound 2-1 at each end thereof and the intermediate compound 2-1. 3 The corresponding epoxy groups react. In the third reaction, the reaction of the terminal of the intermediate compound 2-1 with the intermediate compound 2-2a may be performed before or after the reaction of the terminal of the intermediate compound 2-1 with the intermediate compound 2-2b.

[0357] By carrying out the above steps, it is possible to produce a compound wherein z in formula (1) is 2 and R 3 The two linkers shown are identical and R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or R 2 A compound in which at least one of the three PFPE chains shown is different.

[0358] (2 R 3 Different, R 1 -[B]-[A]-and-[C]-[D]-R 4 Same, 3 Rs 2 Same situation)

[0359] In the first reaction of the second production method, a compound having R 3 The corresponding epoxy group of the halogen compound, and having R 3 The corresponding epoxy halogen compound reacts with the hydroxyl group of the hydroxymethyl group disposed at each end of the above-mentioned fluorine-based compound. 2 One end of the corresponding PFPE chain has an R 3 The corresponding epoxy group has an R 3 The corresponding epoxy intermediate compound 2-1b.

[0360] Next, in the second reaction, with R 1 -[B]-[A]-and-[C]-[D]-R 4 Same, 2 R 3 Same, 3 Rs 2 The same operation was carried out in the same manner to synthesize intermediate compound 2-2.

[0361] Then, in the third reaction, the intermediate compound 2-1b is used instead of the intermediate compound 2-1, and R 1 -[B]-[A]-and-[C]-[D]-R 4 Same, 2 R 3 Same, 3 Rs 2 In the same case, the intermediate compound 2-1b and the intermediate compound 2-2 are reacted in the same manner.

[0362] By carrying out the above steps, it is possible to produce a compound wherein z in formula (1) is 2 and R 3 The two linkers shown are different, R 1 -[B]-[A]-and-[C]-[D]-R 4 The same, and R 2 The three PFPE chains shown are identical compounds.

[0363] (2 R 3 Different, R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or 3 R's 2 Any one or more of the following situations)

[0364] In the first reaction of the second production method, two R 3 Different, R 1 -[B]-[A]-and-[C]-[D]-R 4 Same, 3 Rs 2 The same operation was carried out under the same conditions to synthesize the intermediate compound 2-1b.

[0365] Then, in the second reaction, with 2 R 3 Same, R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or 3 R's 2 When any one or more of the above are different, the intermediate compound 2-2a and the intermediate compound 2-2b are synthesized in the same manner.

[0366] Then, in the third reaction, the intermediate compound 2-1b is used instead of the intermediate compound 2-1, and the two R 3 Same, R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or 3 R's 2 In the case where any one or more of the above are different, the intermediate compound 2-1b and R 1 Side R 3The corresponding epoxy group reacts with the intermediate compound 2-2a to make the intermediate compound 2-1b and R 4 Side R 3 The corresponding epoxy group reacts with the intermediate compound 2-2b.

[0367] By carrying out the above steps, it is possible to produce a compound wherein z in formula (1) is 2 and R 3 The two linkers shown are different, R 1 -[B]-[A]-and-[C]-[D]-R 4 Different and / or R 2 A compound in which at least one of the three PFPE chains shown is different.

[0368] "Lubricants for magnetic recording media"

[0369] The lubricant for a magnetic recording medium according to the present embodiment contains a fluorine-containing ether compound represented by the above formula (1).

[0370] The lubricant of the present embodiment may be mixed with a known material used as a lubricant material as needed, as long as the properties due to the fluorine-containing ether compound represented by the above formula (1) are not impaired.

[0371] Specific examples of known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco), etc. The known material used in combination with the lubricant of the present embodiment preferably has a number average molecular weight of 1,000 to 10,000.

[0372] When the lubricant of the present embodiment contains a material other than the fluorinated ether compound represented by the above formula (1), the content of the fluorinated ether compound represented by the above formula (1) in the lubricant of the present embodiment is preferably 50% by mass or more, more preferably 70% by mass or more.

[0373] Since the lubricant of this embodiment contains the fluorine-containing ether compound represented by the above formula (1), it can form a lubricating layer that has a good effect of suppressing corrosion of the magnetic recording medium even if the thickness is thin, has good adhesion with the protective layer, and has good pickup and peeling characteristics of the magnetic recording medium.

[0374] "Magnetic recording media"

[0375] The magnetic recording medium of this embodiment includes at least a magnetic layer, a protective layer, and a lubricating layer provided in this order on a substrate.

[0376] In the magnetic recording medium of this embodiment, one or more underlayers may be provided between the substrate and the magnetic layer as required. In addition, at least one of an adhesion layer and a soft magnetic layer may be provided between the underlayer and the substrate.

[0377] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0378] The magnetic recording medium 10 of the present embodiment has a structure in which an adhesion layer 12 , a soft magnetic layer 13 , a first underlayer 14 , a second underlayer 15 , a magnetic layer 16 , a protective layer 17 , and a lubricating layer 18 are sequentially provided on a substrate 11 .

[0379] "Substrate"

[0380] As the substrate 11 , 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 can be used.

[0381] In addition, as the substrate 11, a non-magnetic substrate formed of a non-metallic material such as glass, ceramics, silicon, silicon carbide, carbon, or resin can be used, or a non-magnetic substrate having a film of NiP or NiP alloy formed on a base formed of these non-metallic materials can be used.

[0382] "Attachment Layer"

[0383] The adhesion layer 12 prevents the substrate 11 from being corroded when the substrate 11 and the soft magnetic layer 13 provided on the adhesion layer 12 are arranged in contact with each other.

[0384] The material of the adhesion layer 12 can be appropriately selected from, for example, Cr, Cr alloy, Ti, Ti alloy, CrTi, NiAl, AlRu alloy, etc. The adhesion layer 12 can be formed by, for example, sputtering.

[0385] "Soft magnetic layer"

[0386] The soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer including a Ru film, and a second soft magnetic film are stacked in sequence. That is, the soft magnetic layer 13 preferably has a structure in which the upper and lower soft magnetic films of the intermediate layer are antiferrocoupled (AFC) by sandwiching the intermediate layer including a Ru film between the two soft magnetic films.

[0387] Examples of the material of the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy.

[0388] Preferably, any one of Zr, Ta, and Nb is added to the CoFe alloy used for the first soft magnetic film and the second soft magnetic film. This promotes the amorphization of the first soft magnetic film and the second soft magnetic film. As a result, the orientation of the first base layer (seed layer) can be improved, and the floating amount of the magnetic head can be reduced.

[0389] The soft magnetic layer 13 can be formed by, for example, sputtering.

[0390] "1st base layer"

[0391] The first underlayer 14 is a layer for controlling the orientation and crystal size of the second underlayer 15 and the magnetic layer 16 provided thereon.

[0392] Examples of the first base layer 14 include a Cr layer, a Ta layer, a Ru layer, a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, a CrTi alloy layer, and the like.

[0393] The first base layer 14 can be formed by, for example, sputtering.

[0394] "Second base layer"

[0395] The second underlayer 15 is a layer controlled so as to improve the orientation of the magnetic layer 16. The second underlayer 15 is preferably a layer formed of Ru or a Ru alloy.

[0396] The second base layer 15 may be composed of a single layer or a plurality of layers. When the second base layer 15 is composed of a plurality of layers, all layers may be composed of the same material, or at least one layer may be composed of a different material.

[0397] The second base layer 15 can be formed by, for example, sputtering.

[0398] "Magnetic layer"

[0399] The magnetic layer 16 is made of a magnetic film whose easy magnetization axis is oriented vertically or horizontally with respect to the substrate surface. The magnetic layer 16 is a layer containing Co and Pt. In order to improve the SNR characteristics, the magnetic layer 16 may be a layer containing oxide, Cr, B, Cu, Ta, Zr, etc.

[0400] Examples of the oxide contained in the magnetic layer 16 include SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO 2 .

[0401] The magnetic layer 16 may be composed of a single layer or a plurality of magnetic layers formed of materials having different compositions.

[0402] For example, when the magnetic layer 16 is composed of three layers, namely, the first magnetic layer, the second magnetic layer, and the third magnetic layer, which are stacked in order from the bottom, the first magnetic layer is preferably a granular structure formed by a material containing Co, Cr, Pt, and further containing an oxide. As the oxide contained in the first magnetic layer, it is preferred to use, for example, oxides of Cr, Si, Ta, Al, Ti, Mg, Co, etc. Among them, TiO2, Cr2O3, SiO2, etc. can be particularly suitable. In addition, the first magnetic layer is preferably formed by a composite oxide to which two or more oxides are added. Among them, Cr2O3-SiO2, Cr2O3-TiO2, SiO2-TiO2, etc. can be particularly suitable.

[0403] The first magnetic layer may contain one or more elements selected from the group consisting of B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides.

[0404] The second magnetic layer can be made of the same material as that of the first magnetic layer. The second magnetic layer preferably has a granular structure.

[0405] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, and Pt and containing no oxide. In addition to Co, Cr, and Pt, the third magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn.

[0406] When the magnetic layer 16 is formed of a plurality of magnetic layers, a non-magnetic layer is preferably provided between adjacent magnetic layers. When the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer, a non-magnetic layer is preferably provided between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.

[0407] The non-magnetic layer arranged between adjacent magnetic layers of the magnetic layer 16 can be suitably made of, 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.

[0408] It is preferable to use an alloy material containing oxide, metal nitride, or metal carbide in the non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16. Specifically, as oxides, for example, SiO2, Al2O3, Ta2O5, Cr2O3, MgO, Y2O3, TiO2, etc. can be used. As metal nitrides, for example, AlN, Si3N4, TaN, CrN, etc. can be used. As metal carbides, for example, TaC, BC, SiC, etc. can be used.

[0409] The non-magnetic layer can be formed by, for example, sputtering.

[0410] In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer with its easy magnetization axis oriented perpendicularly to the substrate surface. The magnetic layer 16 may be an in-plane magnetic recording magnetic layer.

[0411] The magnetic layer 16 can 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.

[0412] "Protective layer"

[0413] The protective layer 17 protects the magnetic layer 16. The protective layer 17 may be composed of one layer or multiple layers. As the protective layer 17, a carbon-based protective layer may be preferably used, 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 (especially hydroxyl group) contained in the fluorine-containing ether compound in the lubricating layer 18 is further improved, which is preferred.

[0414] 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 carbon nitride 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). In addition, the nitrogen content in the carbon-based protective layer is preferably 4 atomic % to 15 atomic % when measured by X-ray photoelectron spectroscopy (XPS).

[0415] The hydrogen and / or nitrogen contained in the carbon-based protective layer does not need to be uniformly contained in the entire carbon-based protective layer. The carbon-based protective layer is preferably a composition gradient layer 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.

[0416] The protective layer 17 preferably has a thickness of 1 nm to 7 nm. When the protective layer 17 has a thickness of 1 nm or more, sufficient performance as the protective layer 17 can be obtained. When the protective layer 17 has a thickness of 7 nm or less, this is preferred from the viewpoint of reducing the thickness of the protective layer 17.

[0417] As a method for forming the protective layer 17 , a sputtering method using a target containing carbon, a CVD (chemical vapor deposition) method using a hydrocarbon raw material such as ethylene or toluene, an IBD (ion beam deposition) method, or the like can be used.

[0418] When a carbon-based protective layer is formed as the protective layer 17, for example, a film can be formed by a DC magnetron sputtering method. In particular, when a carbon-based protective layer is formed as the protective layer 17, it is preferable to form an amorphous carbon protective layer by a plasma CVD method. The surface of the amorphous carbon protective layer formed by the plasma CVD method is uniform and has little roughness.

[0419] "Lubricating layer"

[0420] 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.

[0421] like Figure 1 As shown, the lubricating layer 18 is formed 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. Therefore, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.

[0422] When the protective layer 17 disposed under the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 is particularly bonded with the protective layer 17 with a high bonding force. As a result, 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 even if the thickness of the lubricating layer 18 is thin, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented.

[0423] The average film thickness of the lubricating layer 18 is preferably More preferably If the average film thickness of the lubricating layer 18 is more than 0.5nm, the lubricating layer 18 is not island-shaped or mesh-shaped but is formed with uniform film thickness. Therefore, the surface of the protective layer 17 can be coated with a high coverage rate by the lubricating layer 18. In addition, by making the average film thickness of the lubricating layer 18 less than 2.0nm, the lubricating layer 18 can be fully filmized, and the floating amount of the magnetic head can be fully reduced.

[0424] "Method for forming a lubricating layer"

[0425] Examples of a method for forming the lubricating layer 18 include a method of preparing a magnetic recording medium in which each layer up to the protective layer 17 is formed on the substrate 11 , applying a lubricating layer forming solution on the protective layer 17 , and drying the solution.

[0426] The lubricant layer-forming solution is obtained by dispersing and dissolving the lubricant for a magnetic recording medium of the above-described embodiment in a solvent as necessary to obtain a viscosity and a concentration suitable for a coating method.

[0427] Examples of the solvent used for the lubricating layer-forming solution include fluorine-based solvents such as Batler (registered trademark) XF (trade name, manufactured by DuPont Mitsui Fluoro Chemical Co., Ltd.).

[0428] The coating method of the lubricating layer forming solution is not particularly limited, and examples thereof include a spin coating method, a spray method, a paper coating method, and a dipping method.

[0429] When the dipping method is used, for example, the following method can be used. First, the substrate 11 on which each layer up to the protective layer 17 is formed is dipped in the lubricating layer forming solution placed in the dipping tank of the dipping coating device. Next, the substrate 11 is pulled out of the dipping tank at a predetermined speed. Thus, the lubricating layer forming solution is applied to the surface of the substrate 11 on the protective layer 17.

[0430] By using the dipping method, the lubricating layer-forming solution can be uniformly applied to the surface of the protective layer 17 , and the lubricating layer 18 can be formed on the protective layer 17 with a uniform film thickness.

[0431] In the present embodiment, it is preferable to perform heat treatment on the substrate 11 on which the lubricating layer 18 is formed. By performing the heat treatment, the adhesion between the lubricating layer 18 and the protective layer 17 is improved, and the adhesion between the lubricating layer 18 and the protective layer 17 is improved.

[0432] The heat treatment temperature is preferably 100° C. to 180° C., 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 is sufficiently obtained. In addition, by setting the heat treatment temperature to 180° C. or lower, thermal decomposition of the lubricating layer 18 caused by the heat treatment can be prevented. The heat treatment time can be appropriately adjusted according to the heat treatment temperature, and is preferably 10 minutes to 120 minutes.

[0433] In the present embodiment, in order to further improve the adhesion of the lubricating layer 18 to the protective layer 17 , the lubricating layer 18 may be irradiated with ultraviolet light (UV) before or after the heat treatment.

[0434] The magnetic recording medium 10 of the present embodiment is provided with at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 in sequence on a substrate 11. For the magnetic recording medium 10 of the present embodiment, a lubricating layer 18 containing the above-mentioned fluorine-containing ether compound is formed in contact with the protective layer 17. Even if the lubricating layer 18 has a thin film thickness, the effect of suppressing the corrosion of the magnetic recording medium is good, and good pickup characteristics and shedding characteristics can be obtained. Therefore, the reliability and durability of the magnetic recording medium 10 of the present embodiment are excellent. In addition, the magnetic recording medium 10 of the present embodiment can make the floating amount of the magnetic head low (for example, less than 10nm), and even in a harsh environment with a variety of uses, it can operate stably for a long time. Therefore, the magnetic recording medium 10 of the present embodiment is particularly suitable as a magnetic disk mounted on a magnetic disk device of the LUL (Load Unload) method.

[0435] Example

[0436] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples. In addition, the present invention is not limited to the following examples.

[0437] [Example 1]

[0438] The compound represented by the above formula (1A) was produced by the method shown below.

[0439] (First reaction)

[0440] Under nitrogen atmosphere, add HOCH2CF2CF2O (CF2CF2CF2O) into a 200 mL eggplant flask. n 20 g of a compound represented by CF2CF2CH2OH (where n represents the average degree of polymerization and is 3.8) (number average molecular weight 909, molecular weight distribution 1.1), 5.3 g of a compound represented by the following formula (12) (molecular weight 404, 13.2 mmol), and 20 mL of tert-butyl alcohol were stirred at room temperature until the mixture became uniform. 0.74 g of potassium tert-butylate (molecular weight 112.21, 6.6 mmol) was further added to the uniform liquid, and the mixture was stirred at 70°C for 16 hours to react.

[0441] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel to which 100 mL of water was added, 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 and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 11.6 g (molecular weight 1313, 8.8 mmol) of the compound represented by the following formula (13) as an intermediate compound 1-1.

[0442] The compound represented by the following formula (12) was synthesized by the method shown below. One equivalent of 3-allyloxy-1,2-propanediol and two equivalents of 2-(2-bromoethoxy)tetrahydro-2H-pyran were reacted. The double bond of the obtained compound was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by the following formula (12).

[0443]

[0444] (In formula (12), THP represents tetrahydropyranyl.)

[0445] (In formula (13), n, which represents the average degree of polymerization, represents 3.8. THP represents tetrahydropyranyl.)

[0446] (Second reaction)

[0447] In a 200 mL eggplant flask under a nitrogen atmosphere, 11.6 g (molecular weight 1313, 8.8 mmol) of the compound represented by formula (13) as the intermediate compound 1-1, 6.0 mL of tert-butyl alcohol, and 0.59 g (molecular weight 112.21, 5.3 mmol) of potassium tert-butylate were added, and stirred at room temperature until the mixture became uniform. 0.50 g (molecular weight 137, 3.6 mmol) of epibromohydrin was added to the uniform liquid, and the mixture was stirred at 70° C. for 24 hours to react.

[0448] The reaction solution obtained after the reaction was returned to room temperature, 31 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 2 hours. The reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline solution, and extracted 3 times with 200 mL of ethyl acetate. The organic layer was washed in the order of 100 mL of saline solution, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline solution, and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was refined by silica gel column chromatography.

[0449] By carrying out the above steps, 4.2 g (number average molecular weight 2349, 1.8 mmol) of compound (1A) (Rf21a in formula (1A) is represented by formula (1AF). Among two Rf21a, n1a representing the average degree of polymerization is 3.8) was obtained.

[0450] The obtained compound (1A) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0451] 1H-NMR (CD3COCD3): δ[ppm]=3.46~4.24(56H)

[0452] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0453] [Example 2]

[0454] In the first reaction, 5.5 g (molecular weight 419, 13.2 mmol) of the compound represented by the following formula (14) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.3 g (number average molecular weight 2377, 1.8 mmol) of the compound represented by the above formula (1B) (Rf21b in formula (1B) is represented by formula (1BF). Among the two Rf21bs, n1b representing the average degree of polymerization is 3.8.).

[0455] The compound represented by formula (14) was synthesized by the following method: Allyl glycidyl ether was reacted with tetrahydropyranyl glycol, and the double bond of the compound obtained by reacting the obtained compound with 2-(3-bromopropoxy)tetrahydro-2H-pyran was oxidized using m-chloroperbenzoic acid to synthesize the compound.

[0456]

[0457] (In formula (14), THP represents tetrahydropyranyl.)

[0458] The obtained compound (1B) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0459] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(56H)

[0460] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0461] [Example 3]

[0462] In the first reaction, instead of HOCH2CF2CF2O (CF2CF2CF2O)n CF2CF2CH2OH, and HOCH2CF2O (CF2CF2O) was used l (CF2O) m 20 g of the compound represented by CF2CH2OH (wherein l represents the average degree of polymerization and m represents the average degree of polymerization) (number average molecular weight 906, molecular weight distribution 1.1) was used, and 5.7 g (molecular weight 432, 13.2 mmol) of the compound represented by the following formula (15) was used instead of the compound represented by formula (12). Except for this, the same operation as in Example 1 was carried out to obtain 4.3 g (number average molecular weight 2399, 1.8 mmol) of the compound represented by the above formula (1C) (Rf11c in formula (1C) is represented by formula (1CF). Among the two Rf11c, l1c representing the average degree of polymerization is 4.0, and m1c representing the average degree of polymerization is 4.0.

[0463] The compound represented by formula (15) was synthesized by the method shown below. One equivalent of 3-allyloxy-1,2-propanediol and two equivalents of 2-(3-bromopropoxy)tetrahydro-2H-pyran were reacted. The double bond of the obtained compound was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by formula (15).

[0464]

[0465] (In formula (15), THP represents tetrahydropyranyl.)

[0466] The obtained compound (1C) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0467] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(8H), 3.39~4.35(56H)

[0468] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(16F), -77.7(4F), -80.3(4F), -91.0~-88.5(32F)

[0469] [Example 4]

[0470] In the first reaction, instead of HOCH2CF2CF2O (CF2CF2CF2O) n CF2CF2CH2OH, and HOCH2CF2O (CF2CF2O) was used l(CF2O) m 20 g of the compound represented by CF2CH2OH (wherein l represents the average degree of polymerization and m represents the average degree of polymerization and is 0) (number average molecular weight 909, molecular weight distribution 1.1) was used, and 6.1 g (molecular weight 461, 13.2 mmol) of the compound represented by the following formula (16) was used instead of the compound represented by formula (12). Except for this, the same operation as in Example 1 was carried out to obtain 4.4 g (number average molecular weight 2460, 1.8 mmol) of the compound represented by the above formula (1D) (Rf11d in formula (1D) is represented by formula (1DF). Among the two Rf11d, l1d representing the average degree of polymerization is 6.3, and m1d representing the average degree of polymerization is 0).

[0471] The compound represented by formula (16) was synthesized by the method shown below. One equivalent of 3-allyloxy-1,2-propanediol and two equivalents of 2-(4-bromobutyloxy)tetrahydro-2H-pyran were reacted. The double bond of the obtained compound was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by the following formula (16).

[0472]

[0473] (In formula (16), THP represents tetrahydropyranyl.)

[0474] The obtained compound (1D) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0475] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(16H), 3.39~4.35(56H)

[0476] 19 F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0477] [Example 5]

[0478] In the first reaction, 5.7 g (molecular weight 432, 13.2 mmol) of the compound represented by the following formula (18) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.3 g (number average molecular weight 2405, 1.8 mmol) of the compound represented by the above formula (1E) (Rf21e in formula (1E) is represented by formula (1EF). Among the two Rf21es, n1e representing the average degree of polymerization is 3.8.).

[0479] The compound represented by formula (18) was synthesized by the method shown below. After the double bond on one side of di(3-butenyl)ether was oxidized to an epoxy group using 1 equivalent of m-chloroperbenzoic acid, the epoxy group was ring-opened using concentrated sulfuric acid to synthesize the compound represented by the following formula (17). 2 equivalents of 2-(2-bromoethoxy)tetrahydro-2H-pyran were reacted with the obtained compound represented by formula (17). Then, the double bond was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by formula (18).

[0480]

[0481] (In formula (18), THP represents tetrahydropyranyl.)

[0482] The obtained compound (1E) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0483] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(8H), 3.39~4.35(56H)

[0484] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0485] [Example 6]

[0486] In the first reaction, 6.8 g (molecular weight 516, 13.2 mmol) of the compound represented by the following formula (20) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.6 g (number average molecular weight 2573, 1.8 mmol) of the compound represented by the above formula (1F) (Rf21f in formula (1F) is represented by formula (1FF). Among the two Rf21f, n1f representing the average degree of polymerization is 3.8).

[0487] The compound represented by formula (20) was synthesized by the method shown below. After the double bond on one side of di(6-heptenyl)ether was oxidized to an epoxy group using 1 equivalent of meta-chloroperbenzoic acid, the epoxy group was ring-opened using concentrated sulfuric acid to synthesize the compound represented by formula (19). 2 equivalents of 2-(2-bromoethoxy)tetrahydro-2H-pyran were reacted with the obtained compound represented by formula (19). Then, it was oxidized using meta-chloroperbenzoic acid to synthesize the compound represented by formula (20).

[0488]

[0489] (In formula (20), THP represents tetrahydropyranyl.)

[0490] The obtained compound (1F) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0491] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(32H), 3.39~4.35(56H)

[0492] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0493] [Example 7]

[0494] In the first reaction, 6.3 g (molecular weight 479, 13.2 mmol) of the compound represented by the following formula (21) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.5 g (number average molecular weight 2497, 1.8 mmol) of the compound represented by the above formula (1G) (Rf21g in formula (1G) is represented by formula (1GF). Among the two Rf21g, n1g representing the average degree of polymerization is 3.8.).

[0495] The compound represented by the following formula (21) is synthesized by reacting allyl alcohol with the compound represented by the above formula (12) and then oxidizing the double bond of the obtained compound using m-chloroperbenzoic acid.

[0496]

[0497] (In formula (21), THP represents tetrahydropyranyl.)

[0498] The obtained compound (1G) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0499] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(68H)

[0500] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0501] [Example 8]

[0502] In the first reaction, 2.5 g (molecular weight 188, 13.2 mmol) of the compound represented by the following formula (23) was used instead of the compound represented by formula (15). The same operations as in Example 3 were carried out to obtain 3.9 g (number average molecular weight 2167, 1.8 mmol) of the compound represented by the above formula (1H) (Rf11h in formula (1H) is represented by formula (1HF). Among the two Rf11h, l1h representing the average degree of polymerization is 4.0, and m1h representing the average degree of polymerization is 4.0.).

[0503] The compound represented by the following formula (23) was synthesized by the following method. The carbonyl site of the alkan-5-one was reduced with lithium aluminum hydride to synthesize a compound represented by the following formula (22). The compound represented by the obtained formula (22) was reacted with epibromohydrin to synthesize a compound represented by the following formula (23).

[0504]

[0505] The obtained compound (1H) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0506] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(40H)

[0507] 19F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0508] [Example 9]

[0509] In the first reaction, 2.7 g (molecular weight 202, 13.2 mmol) of the compound represented by the following formula (24) was used instead of the compound represented by formula (16). The same operations as in Example 4 were carried out to obtain 4.0 g (number average molecular weight 2200, 1.8 mmol) of the compound represented by the above formula (1I) (Rf11i in formula (1I) is represented by formula (1IF). Among the two Rf11i, l1i representing the average degree of polymerization is 6.3, and m1i representing the average degree of polymerization is 0.

[0510] The compound represented by formula (24) is prepared by reacting epibromohydrin with 5-hydroxymethyl-2,2-dimethyl-1,3-di It is synthesized by reaction of alkanes.

[0511]

[0512] The obtained compound (1I) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0513] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(2H), 3.39~4.35(52H)

[0514] 19 F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0515] [Example 10]

[0516] In the first reaction, 2.9 g (molecular weight 216, 13.2 mmol) of the compound represented by the following formula (25) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.0 g (number average molecular weight 2228, 1.8 mmol) of the compound represented by the above formula (1J) (Rf21j in formula (1J) is represented by formula (1JF). Among the two Rf21j, n1j representing the average degree of polymerization is 3.8).

[0517] The compound represented by formula (25) is prepared by reacting epibromohydrin with 5-hydroxyethyl-2,2-dimethyl-1,3- Alkane is thus synthesized.

[0518]

[0519] The obtained compound (1J) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0520] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(6H), 3.39~4.35(42H)

[0521] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0522] [Example 11]

[0523] In the first reaction, 3.6 g (molecular weight 272, 13.2 mmol) of the compound represented by the following formula (26) was used instead of the compound represented by formula (16). The same operations as in Example 4 were carried out to obtain 4.2 g (number average molecular weight 2340, 1.8 mmol) of the compound represented by the above formula (1K) (Rf11k in formula (1K) is represented by formula (1KF). Among the two Rf11ks, l1k representing the average degree of polymerization is 6.3, and m1k representing the average degree of polymerization is 0.).

[0524] The compound represented by formula (26) is prepared by reacting epibromohydrin with 5-hydroxyhexyl-2,2-dimethyl-1,3-di Alkane is thus synthesized.

[0525]

[0526] The obtained compound (1K) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0527] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(22H), 3.39~4.35(42H)

[0528] 19F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0529] [Example 12]

[0530] In the first reaction, 2.7 g (molecular weight 202, 13.2 mmol) of the compound represented by the following formula (27) was used instead of the compound represented by formula (12). The same operations as in Example 1 were carried out to obtain 4.0 g (number average molecular weight 2200, 1.8 mmol) of the compound represented by the above formula (1L) (Rf211 in formula (1L) is represented by formula (1LF). Among the two Rf211, n11 representing the average degree of polymerization is 3.8).

[0531] The compound represented by the formula (27) is synthesized by reacting 3-butenyl bromide with the compound represented by the above formula (22), and then oxidizing the double bond of the obtained compound using m-chloroperbenzoic acid.

[0532]

[0533] The obtained compound (1L) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0534] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(40H)

[0535] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0536] [Example 13]

[0537] In the first reaction, 3.6 g (molecular weight 276, 13.2 mmol) of the compound represented by the following formula (28) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.2 g (number average molecular weight 2349, 1.8 mmol) of the compound represented by the above formula (1M) (Rf21m in formula (1M) is represented by formula (1MF). Among the two Rf21ms, n1m representing the average degree of polymerization is 3.8).

[0538] The compound represented by the formula (28) is synthesized by reacting 3-butene-1-ol with the compound represented by the above formula (23), and then oxidizing the double bond of the obtained compound using m-chloroperbenzoic acid.

[0539]

[0540] The obtained compound (1M) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0541] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(52H)

[0542] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0543] [Example 14]

[0544] In the first reaction, 5.3 g (molecular weight 405, 13.2 mmol) of the compound represented by the following formula (29) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.2 g (number average molecular weight 2321, 1.8 mmol) of the compound represented by the above formula (1N) (Rf21n in formula (1N) is represented by formula (1NF). Among the two Rf21ns, n1n representing the average degree of polymerization is 3.8).

[0545] The compound represented by the formula (29) is synthesized by reacting allyl alcohol with the compound represented by the above formula (23) and then oxidizing the double bond of the obtained compound using m-chloroperbenzoic acid.

[0546]

[0547] The obtained compound (1N) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0548] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(52H)

[0549] 19F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0550] [Example 15]

[0551] In the first reaction, 5.3 g (molecular weight 404, 13.2 mmol) of the compound represented by the following formula (31) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.2 g (number average molecular weight 2349, 1.8 mmol) of the compound represented by the above formula (1O) (Rf21o in formula (1O) is represented by formula (1OF). Among the two Rf21o, n1o representing the average degree of polymerization is 3.8.).

[0552] The compound represented by formula (31) was synthesized by the method shown below. Two equivalents of tetrahydropyranylethylene glycol and one equivalent of epichlorohydrin were reacted to synthesize the compound represented by formula (30). The obtained compound represented by formula (30) was reacted with epibromohydrin to synthesize the compound represented by formula (31).

[0553]

[0554] (In formula (30), THP represents tetrahydropyranyl.)

[0555] (In formula (31), THP represents tetrahydropyranyl.)

[0556] The obtained compound (1O) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0557] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(56H)

[0558] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0559] [Example 16]

[0560] In the first reaction, 5.7 g (molecular weight 433, 13.2 mmol) of the compound represented by the following formula (33) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.3 g (number average molecular weight 2405, 1.8 mmol) of the compound represented by the above formula (1P) (Rf21p in formula (1P) is represented by formula (1PF). Among the two Rf21ps, n1p representing the average degree of polymerization is 3.8.).

[0561] The compound represented by formula (33) was synthesized by the method shown below. Two equivalents of tetrahydropyranyl 1,3-propanediol were reacted with one equivalent of epichlorohydrin to synthesize the compound represented by formula (32). The obtained compound represented by formula (32) was reacted with epibromohydrin to synthesize the compound represented by formula (33).

[0562]

[0563] (In formula (32), THP represents tetrahydropyranyl.)

[0564] (In formula (33), THP represents tetrahydropyranyl.)

[0565] The obtained compound (1P) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0566] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(10H), 3.39~4.35(54H)

[0567] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0568] [Example 17]

[0569] In the first reaction, 6.1 g (molecular weight 461, 13.2 mmol) of the compound represented by the following formula (35) was used instead of the compound represented by formula (15). The same operations as in Example 3 were carried out to obtain 4.4 g (number average molecular weight 2455, 1.8 mmol) of the compound represented by the above formula (1Q) (Rf11q in formula (1Q) is represented by formula (1QF). Among the two Rf11q, l1q representing the average degree of polymerization is 4.0, and m1q representing the average degree of polymerization is 4.0.

[0570] The compound represented by formula (35) was synthesized by the method shown below. Two equivalents of tetrahydropyranyl 1,4-butanediol and one equivalent of epichlorohydrin were reacted to synthesize the compound represented by formula (34). The obtained compound represented by formula (34) was reacted with epibromohydrin to synthesize the compound represented by formula (35).

[0571]

[0572] (In formula (34), THP represents tetrahydropyranyl.)

[0573] (In formula (35), THP represents tetrahydropyranyl.)

[0574] The obtained compound (1Q) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0575] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(18H), 3.39~4.35(54H)

[0576] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0577] [Example 18]

[0578] In the first reaction, 6.8 g (molecular weight 517, 13.2 mmol) of the compound represented by the following formula (37) was used instead of the compound represented by formula (16). The same operation as in Example 4 was carried out to obtain 4.6 g (number average molecular weight 2573, 1.8 mmol) of the compound represented by the above formula (1R) (Rf11r in formula (1R) is represented by formula (1RF). Among the two Rf11r, l1r representing the average degree of polymerization is 6.3, and m1r representing the average degree of polymerization is 0.).

[0579] The compound represented by formula (37) was synthesized by the method shown below. Two equivalents of tetrahydropyranyl 1,6-hexanediol were reacted with one equivalent of epichlorohydrin to synthesize the compound represented by formula (36). The compound represented by formula (36) obtained was reacted with epibromohydrin to synthesize the compound represented by formula (37).

[0580]

[0581] (In formula (36), THP represents tetrahydropyranyl.)

[0582] (In formula (37), THP represents tetrahydropyranyl.)

[0583] The obtained compound (1R) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0584] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(32H), 3.39~4.35(56H)

[0585] 19 F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0586] [Example 19]

[0587] In the first reaction, 7.0 g (molecular weight 531, 13.2 mmol) of the compound represented by the following formula (39) was used instead of the compound represented by formula (15). The same operations as in Example 3 were carried out to obtain 4.7 g (number average molecular weight 2595, 1.8 mmol) of the compound represented by the above formula (1S) (Rf11s in formula (1S) is represented by formula (1SF). Among the two Rf11s, l1s representing the average degree of polymerization is 4.0, and m1s representing the average degree of polymerization is 4.0.

[0588] The compound represented by formula (39) was synthesized by the method shown below. One equivalent of 4-allyloxy-1,2-butanediol and two equivalents of 2-(6-bromohexyloxy)tetrahydro-2H-pyran were reacted to synthesize the compound represented by formula (38). The double bond of the obtained compound represented by formula (38) was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by formula (39).

[0589]

[0590] (In formula (38), THP represents tetrahydropyranyl.)

[0591] (In formula (39), THP represents tetrahydropyranyl.)

[0592] The obtained compound (1S) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0593] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(36H), 3.39~4.35(56H)

[0594] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0595] [Example 20]

[0596] In the first reaction, 7.7 g (molecular weight 587, 13.2 mmol) of the compound represented by the following formula (41) was used instead of the compound represented by formula (16). The same operations as in Example 4 were carried out to obtain 4.9 g (number average molecular weight 2713, 1.8 mmol) of the compound represented by the above formula (1T) (Rf11t in formula (1T) is represented by formula (1TF). Among the two Rf11t, l1t representing the average degree of polymerization is 6.3, and m1t representing the average degree of polymerization is 0.).

[0597] The compound represented by formula (41) was synthesized by the method shown below. One equivalent of 8-allyloxy-1,2-octanediol and two equivalents of 2-(6-bromohexyloxy)tetrahydro-2H-pyran were reacted to synthesize the compound represented by formula (40). The double bond of the obtained compound represented by formula (40) was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by formula (41).

[0598]

[0599] (In formula (40), THP represents tetrahydropyranyl.)

[0600] (In formula (41), THP represents tetrahydropyranyl.)

[0601] The obtained compound (1T) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0602] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(52H), 3.39~4.35(56H)

[0603] 19F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0604] [Example 21]

[0605] In the first reaction, 6.5 g (molecular weight 493, 13.2 mmol) of the compound represented by the following formula (43) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.5 g (number average molecular weight 2525, 1.8 mmol) of the compound represented by the above formula (1U) (Rf21u in formula (1U) is represented by formula (1UF). Among the two Rf21u, n1u representing the average degree of polymerization is 3.8.).

[0606] The compound represented by formula (43) was synthesized by the method shown below. Two equivalents of tetrahydropyranyl diglycol and one equivalent of epichlorohydrin were reacted to synthesize the compound represented by formula (42). The obtained compound represented by formula (42) was reacted with epibromohydrin to synthesize the compound represented by formula (43).

[0607]

[0608] (In formula (42), THP represents tetrahydropyranyl.)

[0609] (In formula (43), THP represents tetrahydropyranyl.)

[0610] The obtained compound (1U) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0611] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(72H)

[0612] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0613] [Example 22]

[0614] In the first reaction, 5.9 g (molecular weight 445, 13.2 mmol) of the compound represented by the following formula (45) was used instead of the compound represented by formula (12). The same operation as in Example 1 was carried out to obtain 4.1 g (number average molecular weight 2260, 1.8 mmol) of the compound represented by the above formula (1V) (Rf21v in formula (1V) is represented by formula (1VF). Among the two Rf21v, n1v representing the average degree of polymerization is 3.8).

[0615] The compound represented by formula (45) was synthesized by the method shown below. 2-(bromomethyl)-2-(hydroxymethyl)-1,3-propanediol and 3,4-dihydro-2H-pyran were reacted, and the hydroxyl group of 2-(bromomethyl)-2-(hydroxymethyl)-1,3-propanediol was protected with a tetrahydropyranyl group to synthesize the compound represented by formula (44). After reacting the obtained compound represented by formula (44) with allyl alcohol, the double bond of the obtained compound was oxidized using m-chloroperbenzoic acid to synthesize the compound represented by formula (45).

[0616]

[0617] (In formula (44), THP represents tetrahydropyranyl.)

[0618] (In formula (45), THP represents tetrahydropyranyl.)

[0619] The obtained compound (1V) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0620] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(48H)

[0621] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0622] [Example 23]

[0623] The compound represented by the above formula (2A) was produced by the method shown below.

[0624] (First reaction)

[0625] Under nitrogen atmosphere, add HOCH2CF2CF2O (CF2CF2CF2O) into a 200 mL eggplant flask.n 12.2 g (20 mmol) of a compound represented by CF2CF2CH2OH (where n in the formula represents the average degree of polymerization is 2.0) (number average molecular weight 610, molecular weight distribution 1.1), 1.76 g (44 mmol) of 60% sodium hydride, and 15.6 mL of N,N-dimethylformamide were stirred at room temperature until it became uniform. 3.45 mL (42 mmol) of epibromohydrin was added to the uniform liquid, and the mixture was stirred at 40°C for 2 hours to react.

[0626] The reaction product obtained after the reaction was cooled to 25 ° C, 80 mL of water was added to stop the reaction, transferred to a separatory funnel, and extracted twice with 150 mL of ethyl acetate. The organic layer was washed with saturated brine and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was refined by silica gel column chromatography to obtain 3.5 g (molecular weight 580, 6.0 mmol) of the compound shown in the following formula (46) as an intermediate compound 2-1.

[0627]

[0628] (In formula (46), n, which represents the average degree of polymerization, is 2.0.)

[0629] (Second reaction)

[0630] Under nitrogen atmosphere, add HOCH2CF2CF2O (CF2CF2CF2O) into a 200 mL eggplant flask. n 14 g of a compound represented by CF2CF2CH2OH (where n in the formula represents an average degree of polymerization of 2.0) (number average molecular weight 610, molecular weight distribution 1.1), 5.4 g of a compound represented by the above formula (12) (molecular weight 405, 13 mmol), and 20 mL of tert-butyl alcohol were stirred at room temperature until the mixture became uniform. 0.74 g of potassium tert-butylate (molecular weight 112, 6.6 mmol) was further added to the uniform liquid, and the mixture was stirred at 70°C for 16 hours to react.

[0631] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel to which 100 mL of water was added, 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 and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 12 g (molecular weight 1015, 12.0 mmol) of the compound represented by the above formula (13) as the intermediate compound 2-2 (in formula (13), n representing the average degree of polymerization represents 2.0. THP represents tetrahydropyranyl).

[0632] (Third reaction)

[0633] In a nitrogen atmosphere, 10 g of the intermediate compound 2-2 represented by formula (13) (where n represents the average degree of polymerization is 2.0), 0.38 g of potassium tert-butoxide, and 9.5 mL of tert-butanol were added to a 200 mL eggplant flask, and stirred at room temperature until it became uniform. 2.2 g of the intermediate compound 2-1 represented by formula (46) (where n represents the average degree of polymerization is 2.0) was further added to the uniform liquid, and stirred at 70°C for 16 hours to react.

[0634] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel added with 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 and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain the compound represented by the above formula (2A) (Rf22a in formula (2A) is represented by formula (2AF). Among the three Rf22a, n2a representing the average degree of polymerization is 2.0.) 4.4 g (molecular weight 2419, 1.8 mmol).

[0635] The obtained compound (2A) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0636] 1 H-NMR (CD3COCD3): δ[ppm]=3.46~4.24(66H)

[0637] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0638] [Example 24]

[0639] In the second reaction, 5.6 g of the compound represented by formula (14) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.4 g (molecular weight 2447, 1.8 mmol) of the compound represented by the above formula (2B) (Rf22b in formula (2B) is represented by formula (2BF). Among the three Rf22bs, n2b representing the average degree of polymerization is 2.0.

[0640] The obtained compound (2B) is subjected to 1 H-NMR determination and 19The structure was identified based on the following results from F-NMR measurement.

[0641] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(66H)

[0642] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0643] [Example 25]

[0644] In the first and second reactions, HOCH2CF2CF2O (CF2CF2CF2O) is substituted n CF2CF2CH2OH, and HOCH2CF2O (CF2CF2O) was used l (CF2O) m 12 g of the compound represented by CF2CH2OH (wherein l represents the average degree of polymerization and m represents the average degree of polymerization) (number average molecular weight 615, molecular weight distribution 1.1) was used. In the second reaction, 5.7 g of the compound represented by formula (15) was used instead of the compound represented by formula (12). Otherwise, the same operation as in Example 23 was carried out to obtain 4.5 g (number average molecular weight 2490, 1.8 mmol) of the compound represented by the above formula (2C) (Rf12c in formula (2C) is represented by formula (2CF). Among the three Rf12c, l2c representing the average degree of polymerization is 2.4, and m2c representing the average degree of polymerization is 2.4.

[0645] The obtained compound (2C) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0646] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(8H), 3.39~4.35(66H)

[0647] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0648] [Example 26]

[0649] In the first and second reactions, HOCH2CF2CF2O (CF2CF2CF2O) is substituted n CF2CF2CH2OH, and HOCH2CF2O (CF2CF2O) was used l (CF2O) m 12 g of the compound represented by CF2CH2OH (wherein l represents the average degree of polymerization and m represents the average degree of polymerization and is 0) (number average molecular weight 619, molecular weight distribution 1.1) was prepared. In the second reaction, 6.0 g of the compound represented by formula (16) was used instead of the compound represented by formula (12). Otherwise, the same operation as in Example 23 was performed to obtain 4.6 g (number average molecular weight 2557, 1.8 mmol) of the compound represented by the above formula (2D) (Rf12d in formula (2D) is represented by formula (2DF). Among the three Rf12d, l2d representing the average degree of polymerization is 3.8, and m2d representing the average degree of polymerization is 0).

[0650] The obtained compound (2D) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0651] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(16H), 3.39~4.35(66H)

[0652] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0653] [Example 27]

[0654] In the second reaction, 5.7 g of the compound represented by formula (18) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.5 g (molecular weight 2475, 1.8 mmol) of the compound represented by the above formula (2E) (Rf22e in formula (2E) is represented by formula (2EF). Among the three Rf22es, n2e representing the average degree of polymerization is 2.0.

[0655] The obtained compound (2E) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0656] 1H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(8H), 3.39~4.35(66H)

[0657] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0658] [Example 28]

[0659] In the second reaction, 6.8 g of the compound represented by formula (20) was used instead of the compound represented by formula (12). Except for this, the same operation as in Example 23 was carried out to obtain 4.8 g (molecular weight 2644, 1.8 mmol) of the compound represented by the above formula (2F) (Rf22f in formula (2F) is represented by formula (2FF). Among the three Rf22f, n2f representing the average degree of polymerization is 2.0.

[0660] The obtained compound (2F) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0661] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(32H), 3.39~4.35(66H)

[0662] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0663] [Example 29]

[0664] In the second reaction, 6.4 g of the compound represented by formula (21) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.6 g (molecular weight 2567, 1.8 mmol) of the compound represented by the above formula (2G) (Rf22g in formula (2G) is represented by formula (2GF). Among the three Rf22g, n2g representing the average degree of polymerization is 2.0.

[0665] The obtained compound (2G) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0666] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(78H)

[0667] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0668] [Example 30]

[0669] In the second reaction, 2.5 g of the compound represented by formula (23) was used instead of the compound represented by formula (15). The same operations as in Example 25 were carried out to obtain 4.1 g (number average molecular weight 2257, 1.8 mmol) of the compound represented by the above formula (2H) (Rf12h in formula (2H) is represented by formula (2HF). Among the three Rf12h, l2h representing the average degree of polymerization is 2.4, and m2h representing the average degree of polymerization is 2.4.

[0670] The obtained compound (2H) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0671] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(50H)

[0672] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0673] [Example 31]

[0674] In the second reaction, 2.6 g of the compound represented by formula (24) was used instead of the compound represented by formula (16). The same operations as in Example 26 were carried out to obtain 4.1 g (number average molecular weight 2297, 1.8 mmol) of the compound represented by the above formula (2I) (Rf12i in formula (2I) is represented by formula (2IF). Among the three Rf12i, l2i representing the average degree of polymerization is 3.8, and m2i representing the average degree of polymerization is 0.

[0675] The obtained compound (2I) is subjected to 1 H-NMR determination and 19The structure was identified based on the following results from F-NMR measurement.

[0676] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(2H), 3.39~4.35(62H)

[0677] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0678] [Example 32]

[0679] In the second reaction, 2.9 g of the compound represented by formula (25) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.1 g (molecular weight 2299, 1.8 mmol) of the compound represented by the above formula (2J) (Rf22j in formula (2J) is represented by formula (2JF). Among the three Rf22j, n2j representing the average degree of polymerization is 2.0.).

[0680] The obtained compound (2J) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0681] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(6H), 3.39~4.35(52H)

[0682] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0683] [Example 33]

[0684] In the second reaction, 3.6 g of the compound represented by formula (26) was used instead of the compound represented by formula (16). The same operations as in Example 26 were carried out to obtain 4.4 g (number average molecular weight 2437, 1.8 mmol) of the compound represented by the above formula (2K) (Rf12k in formula (2K) is represented by formula (2KF). Among the three Rf12k, l2k representing the average degree of polymerization is 3.8, and m2k representing the average degree of polymerization is 0.

[0685] The obtained compound (2K) is subjected to 1H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0686] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(22H), 3.39~4.35(52H)

[0687] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0688] [Example 34]

[0689] In the second reaction, 2.7 g of the compound represented by formula (27) was used instead of the compound represented by formula (12). The same operations as in Example 23 were performed to obtain 4.1 g (molecular weight 2271, 1.8 mmol) of the compound represented by the above formula (2L) (Rf221 in formula (2L) is represented by formula (2LF). Among the three Rf221, n21 representing the average degree of polymerization is 2.0.

[0690] The obtained compound (2L) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0691] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(50H)

[0692] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0693] [Example 35]

[0694] In the second reaction, 3.7 g of the compound represented by formula (28) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.4 g (molecular weight 2419, 1.8 mmol) of the compound represented by the above formula (2M) (Rf22m in formula (2M) is represented by formula (2MF). Among the three Rf22m, n2m representing the average degree of polymerization is 2.0.

[0695] The obtained compound (2M) was subjected to 1H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0696] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(62H)

[0697] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0698] [Example 36]

[0699] In the second reaction, 3.5 g of the compound represented by formula (29) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.3 g (molecular weight 2391, 1.8 mmol) of the compound represented by the above formula (2N) (Rf22n in formula (2N) is represented by formula (2NF). Among the three Rf22n, n2n representing the average degree of polymerization is 2.0.

[0700] The obtained compound (2N) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0701] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(62H)

[0702] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0703] [Example 37]

[0704] In the second reaction, 5.4 g of the compound represented by formula (31) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.4 g (molecular weight 2419, 1.8 mmol) of the compound represented by the above formula (2O) (Rf22o in formula (2O) is represented by formula (2OF). Among the three Rf22o, n2o representing the average degree of polymerization is 2.0.).

[0705] The obtained compound (2O) is subjected to1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0706] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(66H)

[0707] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0708] [Example 38]

[0709] In the second reaction, 5.7 g of the compound represented by formula (33) was used instead of the compound represented by formula (12). Except for this, the same operation as in Example 23 was carried out to obtain 4.5 g (molecular weight 2475, 1.8 mmol) of the compound represented by the above formula (2P) (Rf22p in formula (2P) is represented by formula (2PF). Among the three Rf22p, n2p representing the average degree of polymerization is 2.0.

[0710] The obtained compound (2P) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0711] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(10H), 3.39~4.35(64H)

[0712] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0713] [Example 39]

[0714] In the second reaction, 6.1 g of the compound represented by formula (35) was used instead of the compound represented by formula (15). The same operations as in Example 25 were carried out to obtain 4.6 g (number average molecular weight 2546, 1.8 mmol) of the compound represented by the above formula (2Q) (Rf12q in formula (2Q) is represented by formula (2QF). Among the three Rf12q, l2q representing the average degree of polymerization is 2.4, and m2q representing the average degree of polymerization is 2.4.

[0715] The obtained compound (2Q) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0716] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(18H), 3.39~4.35(64H)

[0717] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0718] [Example 40]

[0719] In the second reaction, 6.8 g of the compound represented by formula (37) was used instead of the compound represented by formula (16). Except for this, the same operation as in Example 26 was carried out to obtain 4.8 g (number average molecular weight 2670, 1.8 mmol) of the compound represented by the above formula (2R) (Rf12r in formula (2R) is represented by formula (2RF). Among the three Rf12r, l2r representing the average degree of polymerization is 3.8, and m2r representing the average degree of polymerization is 0.

[0720] The obtained compound (2R) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0721] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(32H), 3.39~4.35(66H)

[0722] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0723] [Example 41]

[0724] In the second reaction, 7.0 g of the compound represented by formula (39) was used instead of the compound represented by formula (15). The same operations as in Example 25 were carried out to obtain 4.8 g (number average molecular weight 2686, 1.8 mmol) of the compound represented by the above formula (2S) (Rf12s in formula (2S) is represented by formula (2SF). Among the three Rf12s, l2s representing the average degree of polymerization is 2.4, and m2s representing the average degree of polymerization is 2.4.

[0725] The obtained compound (2S) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0726] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(36H), 3.39~4.35(66H)

[0727] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0728] [Example 42]

[0729] In the second reaction, 7.7 g of the compound represented by formula (41) was used instead of the compound represented by formula (16). The same operations as in Example 26 were carried out to obtain 5.1 g (number average molecular weight 2810, 1.8 mmol) of the compound represented by the above formula (2T) (Rf12t in formula (2T) is represented by formula (2TF). Among the three Rf12t, l2t representing the average degree of polymerization is 3.8, and m2t representing the average degree of polymerization is 0.

[0730] The obtained compound (2T) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0731] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(52H), 3.39~4.35(66H)

[0732] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0733] [Example 43]

[0734] In the second reaction, 6.5 g of the compound represented by formula (43) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.7 g (molecular weight 2595, 1.8 mmol) of the compound represented by the above formula (2U) (Rf22u in formula (2U) is represented by formula (2UF). Among the three Rf22u, n2u representing the average degree of polymerization is 2.0.

[0735] The obtained compound (2U) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0736] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(82H)

[0737] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0738] [Example 44]

[0739] In the second reaction, 5.9 g of the compound represented by formula (45) was used instead of the compound represented by formula (12). The same operation as in Example 23 was carried out to obtain 4.2 g (molecular weight 2331, 1.8 mmol) of the compound represented by the above formula (2V) (Rf22v in formula (2V) is represented by formula (2VF). Among the three Rf22v, n2v representing the average degree of polymerization is 2.0.

[0740] The obtained compound (2V) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0741] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.35(58H)

[0742] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0743] When the compounds (1A) to (1V) and (2A) to (2V) of Examples 1 to 44 obtained in this manner are applied to the formula (1), the values ​​of z, R 1 , [A], [B], R 2 , R 3 , [C], [D], R 4 The structures are shown in Tables 5 to 9.

[0744] Table 5

[0745]

[0746] Table 6

[0747]

[0748] Table 7

[0749]

[0750] Table 8

[0751]

[0752] Table 9

[0753]

[0754] [Comparative Example 1]

[0755] According to the method described in Patent Document 1, a compound represented by the following formula (3A) was synthesized.

[0756]

[0757] (Rf13a in formula (3A) is the PFPE chain represented by the above formula (3AF). Among the two Rf13a, l3a representing the average degree of polymerization is 4.0, and m3a representing the average degree of polymerization is 4.0.)

[0758] [Comparative Example 2]

[0759] By the method described in Patent Document 2, a compound represented by the following formula (3B) was synthesized.

[0760]

[0761] (Rf23b in formula (3B) is the PFPE chain represented by the above formula (3BF). Among the two Rf23b, n3b indicating the average degree of polymerization is 3.8.)

[0762] [Comparative Example 3]

[0763] According to the method described in Patent Document 4, a compound represented by the following formula (3C) was synthesized.

[0764]

[0765] (Rf23c in formula (3C) is the PFPE chain represented by the above formula (3CF). Among the two Rf23c, n3c representing the average degree of polymerization is 3.8.)

[0766] [Comparative Example 4]

[0767] By the method described in Patent Document 4, a compound represented by the following formula (3D) was synthesized.

[0768]

[0769] (Rf23d in formula (3D) is the PFPE chain represented by the above formula (3DF). Me represents a methyl group. Among the two Rf23d, n3d representing the average degree of polymerization is 3.8.)

[0770] [Comparative Example 5]

[0771] According to the method described in Patent Document 4, a compound represented by the following formula (3E) was synthesized.

[0772]

[0773] (Rf23e in formula (3E) is the PFPE chain represented by the above formula (3EF). Among the two Rf23e, n3e indicating the average degree of polymerization is 3.8.)

[0774] [Comparative Example 6]

[0775] By the method described in Patent Document 3, a compound represented by the following formula (3F) was synthesized.

[0776]

[0777] (Rf23f in formula (3F) is the PFPE chain represented by the above formula (3FF). Among the two Rf23f, n3f indicating the average degree of polymerization is 3.8.)

[0778] [Comparative Example 7]

[0779] By the method described in Patent Document 6, a compound represented by the following formula (3G) was synthesized.

[0780]

[0781] (Rf13g in formula (3G) is a PFPE chain represented by the above formula (3GF). Among the three Rf13g, the central Rf13g has l3g indicating the average degree of polymerization of 3.8 and m3g indicating the average degree of polymerization of 0. In the two Rf13g on the terminal side, l3g indicating the average degree of polymerization of 2.4 and m3g indicating the average degree of polymerization of 2.4.)

[0782] [Comparative Example 8]

[0783] By the method described in Patent Document 7, a compound represented by the following formula (3H) was synthesized.

[0784]

[0785] (Rf13h in formula (3H) is a PFPE chain represented by the above formula (3HF). Among the three Rf13h, l3h representing the average degree of polymerization is 3.8, and m3h representing the average degree of polymerization is 0.)

[0786] [Comparative Example 9]

[0787] According to the method described in Patent Document 5, a compound represented by the following formula (3I) was synthesized.

[0788]

[0789] (Rf13i in formula (3I) is the PFPE chain represented by the above formula (3IF). Among the three Rf13i, l3i representing the average degree of polymerization is 3.8, and m3i representing the average degree of polymerization is 0.)

[0790] [Comparative Example 10]

[0791] By the method described in Patent Document 8, a compound represented by the following formula (3J) was synthesized.

[0792]

[0793] (In formula (3J), l3j representing the average degree of polymerization is 4.5, and m3j representing the average degree of polymerization is 4.5.) [Comparative Example 11]

[0794] By the method described in Patent Document 8, a compound represented by the following formula (3K) was synthesized.

[0795]

[0796] (In formula (3K), l3k representing the average degree of polymerization represents 4.5, and m3k representing the average degree of polymerization represents 4.5.)

[0797] The number average molecular weight (Mn) of the compounds of Examples 1 to 44 and Comparative Examples 1 to 11 obtained in this manner was measured by the above-mentioned method. The results are shown in Tables 10 to 12.

[0798] Next, a lubricant layer forming solution was prepared by the method described below using the compounds obtained in Examples 1 to 44 and Comparative Examples 1 to 11. Furthermore, the lubricant layer of a magnetic recording medium was formed by the method described below using the obtained lubricant layer forming solution, thereby obtaining magnetic recording media of Examples 1 to 44 and Comparative Examples 1 to 11.

[0799] [Lubricating layer forming solution]

[0800] The compounds obtained in Examples 1 to 44 and Comparative Examples 1 to 11 were dissolved in a fluorine-based solvent, Batorel (registered trademark) XF (trade name, manufactured by Mitsui Dupont Fluoro Chemical Co., Ltd.), respectively, to form a film having a thickness of 100% to 100% when applied on the protective layer. The solution was diluted with Batler XF in a manner of 0.001 mass % to 0.01 mass % to prepare a lubricating layer forming solution.

[0801] "Magnetic recording media"

[0802] A magnetic recording medium was prepared in which an adhesion layer, a soft magnetic layer, a first underlayer, a second underlayer, a magnetic layer, and a protective layer were sequentially provided on a substrate having a diameter of 65 mm. The protective layer was formed of carbon.

[0803] On the protective layer of the magnetic recording medium having each layer formed thereon, the lubricating layer forming solutions of Examples 1 to 44 and Comparative Examples 1 to 11 were applied by dipping. The dipping method was performed under the conditions of dipping speed of 10 mm / sec, dipping time of 30 sec, and pulling speed of 1.2 mm / sec.

[0804] Then, the magnetic recording medium coated with the lubricating layer forming solution is added to a constant temperature bath and heat treated at 120°C for 10 minutes to remove the solvent in the lubricating layer forming solution and improve the adhesion between the protective layer and the lubricating layer, thereby forming a lubricating layer on the protective layer to obtain a magnetic recording medium.

[0805] (Film thickness measurement)

[0806] The lubricating layers of the magnetic recording media of Examples 1 to 44 and Comparative Examples 1 to 11 obtained in this manner were measured for the peak height in CF vibration expansion using a Fourier transform infrared spectrophotometer (FT-IR, trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific). Next, the film thickness of the lubricating layer was calculated from the measured value of the peak height in CF vibration expansion of the lubricating layer using a correlation formula obtained by the method described below.

[0807] (Calculation method of correlation formula)

[0808] A magnetic disk having an adhesive layer, a soft magnetic layer, a first base layer, a second base layer, a magnetic layer and a protective layer is prepared in sequence on a substrate having a diameter of 65 mm. (by The film thickness of the interval) forms a lubricating layer respectively.

[0809] Then, for each disk with a lubricating layer formed, the film thickness increase from the disk surface without a lubricating layer was measured using an ellipsometer, and the film thickness of the lubricating layer was determined. In addition, for each disk with a lubricating layer formed, the peak height in CF vibration expansion was measured using FT-IR.

[0810] Furthermore, a correlation equation between the peak height obtained by FT-IR and the film thickness of the lubricating layer obtained by using an ellipsometer was determined.

[0811] Next, the magnetic recording media of Examples 1 to 44 and Comparative Examples 1 to 11 were evaluated by subjecting the following pickup characteristic test, peeling characteristic test, and corrosion resistance test.

[0812] (Pickup characteristics test)

[0813] The magnetic recording medium and the magnetic head are mounted on the spin stand, and the magnetic head is rotated at room temperature under reduced pressure (about 250 Torr) to float the magnetic head at a fixed point for 10 minutes. Then, the surface of the magnetic head opposite to the magnetic recording medium is analyzed using an ESCA (Electron Spectroscopy for Chemical Analysis) analysis device. The intensity (signal intensity (au)) of the peak derived from fluorine obtained by analysis using the ESCA analysis device represents the amount of lubricant attached to the magnetic head. Using the obtained signal intensity, the pickup characteristics are evaluated by the evaluation criteria shown below.

[0814] (Evaluation criteria for pickup characteristics)

[0815] A (excellent): signal strength below 160 (very little adhesion)

[0816] B (good): signal strength 161 to 300 (small amount of adhesion)

[0817] C (qualified): signal strength 301-1000 (high adhesion)

[0818] D (failed): signal strength 1001 or more (very high amount of adhesion)

[0819] (Shedding characteristics test)

[0820] The magnetic recording medium was mounted on the spin stand and rotated at a rotation speed of 10,000 rpm for 72 hours under an environment of 80°C. Before and after this operation, the film thickness of the lubricating layer at a position with a radius of 20 mm from the center of the magnetic recording medium was measured using FT-IR by the above method, and the film thickness reduction rate of the lubricating layer before and after the test was calculated. Using the calculated film thickness reduction rate, the shedding characteristics were evaluated according to the evaluation criteria shown below.

[0821] (Evaluation criteria for shedding characteristics)

[0822] A (excellent): film thickness reduction rate is less than 2%

[0823] B (good): Film thickness reduction rate is more than 2% and less than 3%

[0824] C (pass): Film thickness reduction rate is more than 3% and less than 8%

[0825] D (failure): film thickness reduction rate exceeds 8%

[0826] (Corrosion resistance test)

[0827] The magnetic recording medium was exposed to the conditions of 85°C and 90% relative humidity for 48 hours. Then, the number of corrosion spots with a diameter of 5 μm or more generated on the surface of the magnetic recording medium was counted using an optical surface analysis device (Candela 7140 manufactured by Kellner Tencore Co., Ltd.) and evaluated based on the following evaluation criteria.

[0828] (Evaluation criteria for corrosion resistance test)

[0829] A (excellent): less than 150

[0830] B (good): 150 or more and less than 200

[0831] C (qualified): 200 or more and less than 400

[0832] D (failure): more than 400

[0833] Table 10

[0834]

[0835] Table 11

[0836]

[0837] Table 12

[0838]

[0839] As shown in Tables 10 and 11, the magnetic recording media of Examples 1 to 44 were evaluated as A to B in all evaluation items. Therefore, it was confirmed that the results of the pickup property test, the peeling property test, and the corrosion resistance test of the lubricating layer of the magnetic recording media of Examples 1 to 44 were all good.

[0840] In particular, the results of the pickup characteristic test and the peeling characteristic test of the lubricating layer of the magnetic recording media of Examples 1 to 5, 7 to 10, 12 to 27, 29 to 32, and 34 to 44 were all A, which were good. The compounds (1A) to (1E), (1G) to (1J), (1L) to (1V), (2A) to (2E), (2G) to (2J), and (2L) to (2V) used in the lubricating layers of the above Examples were all R 1 -[B]-[A]-and-[C]-[D]-R 4 The number of carbon atoms contained is relatively small, or even if the number of carbon atoms is large, the distance from the carbon atom that becomes the branch point to the primary hydroxyl group in the branched terminal group is not too close, which is appropriate. 1 -[B]-[A]-and-[C]-[D]-R 4 The excellent adsorption force of the secondary hydroxyl groups present in the protective layer and the excellent intermolecular force balance of the primary hydroxyl groups in the branched terminal groups work effectively, and the adhesion of the hydroxyl groups to the protective layer is more effectively obtained. As a result, it is inferred that the adhesion of the lubricant to the magnetic head is suppressed, showing excellent pickup characteristics. In addition, it is inferred that the adhesion of the lubricating layer to the protective layer is maintained, and good shedding characteristics are obtained.

[0841] On the other hand, as shown in Table 12, the results of the pickup characteristic test and the dropout characteristic test of the magnetic recording media of Comparative Examples 1 to 11 were all C to D.

[0842] In Comparative Examples 1 and 7, the compound used in the lubricating layer is equivalent to R 1 and R 4 The structures of each have only one primary hydroxyl group. Therefore, the lubricating layers of Comparative Examples 1 and 7 are different from those containing R 1 and R 4Compared with the lubricating layers of Examples 1 to 44, which are compounds of branched terminal groups having 2 or 3 primary hydroxyl groups, it is difficult to obtain adhesion to the protective layer. As a result, it is estimated that in Comparative Examples 1 and 7, the lubricant adheres to the magnetic head, and the result of the pickup characteristic test is C. In addition, it is estimated that in Comparative Examples 1 and 7, it is difficult to maintain adhesion to the protective layer, so the result of the peeling characteristic test is C.

[0843] In Comparative Examples 2 to 6 and 9, the compound used in the lubricating layer is equivalent to R 1 and R 4 The structure does not have a branched terminal group having two primary hydroxyl groups, and the two hydroxyl groups arranged at both ends are respectively bonded to adjacent carbon atoms. For the lubricating layer containing the compound used in Comparative Examples 2 to 6 and 9, any of the two hydroxyl groups arranged at both ends of the compound is not easy to adhere to the protective layer. As a result, it is inferred that in Comparative Examples 2 to 6 and 9, the lubricant adheres to the magnetic head, and the result of the pickup characteristic test is D. In addition, it is inferred that the adhesion to the protective layer cannot be maintained, and the result of the shedding characteristic test is D. It is further inferred that in Comparative Examples 2 to 6 and 9, since a compound in which the two hydroxyl groups arranged at both ends are respectively bonded to adjacent carbon atoms is used, the adhesion to the protective layer is insufficient, and the result of the corrosion resistance test is C.

[0844] In Comparative Example 8, the compound used in the lubricating layer is equivalent to R 1 and R 4 The structures of -[B]-[A]- and -[C]-[D]- have only one primary hydroxyl group, and there is only a divalent linking group corresponding to one of the -[B]-[A]- and -[C]-[D]- structures. Therefore, it is inferred that the adhesion of the lubricating layer to the protective layer of Comparative Example 8 is insufficient. As a result, it is inferred that in Comparative Example 8, the lubricant adheres to the magnetic head, and the result of the pickup characteristic test is D. In addition, it is inferred that in Comparative Example 8, the adhesion to the protective layer cannot be maintained, and the result of the shedding characteristic test is also D. It is further inferred that in Comparative Example 8, since a compound with only OH at one end is used, the adhesion to the protective layer is insufficient, and the result of the corrosion resistance test is C.

[0845] In Comparative Examples 10 and 11, a compound having two primary hydroxyl terminal groups arranged at both ends of the molecule was used for the lubricating layer. However, the compound used for the lubricating layer in Comparative Examples 10 and 11 does not contain a divalent linking group that conforms to the -[B]-[A]- structure and the -[C]-[D]- structure in the fluorinated ether compound represented by formula (1). Therefore, it is estimated that the lubricating layers of Comparative Examples 10 and 11 have poor adsorption to the protective layer compared to the lubricating layers of Examples 1 to 44, and the results of the pickup characteristic test are C or D, and the result of the shedding characteristic test is D. It is further estimated that the compound used for the lubricating layer in Comparative Examples 10 and 11 has only one PFPE chain, so the hydrophobicity of the lubricating layer becomes insufficient, and the result of the corrosion resistance test is D.

[0846] Industrial Availability

[0847] Provided is a fluorine-containing ether compound which can form a lubricating layer which has good adhesion to a protective layer, has a good effect of suppressing corrosion of a magnetic recording medium even with a thin thickness, and can suppress pickup and peeling, and can be suitably used as a material for a lubricant for a magnetic recording medium.

[0848] Explanation of symbols

[0849] 10···magnetic recording medium, 11···substrate, 12···adhesion layer, 13···soft magnetic layer, 14···first base layer, 15···second base layer, 16···magnetic layer, 17···protective layer, 18···lubricating layer.

Claims

1. A fluorine-containing ether compound, It is characterized in that It is represented by the following formula (1): R 1 -[B]-[A]-CH 2 -R 2 [-CH 2 -R 3 -CH 2 -R 2 ] z -CH 2 -[C]-[D]-R 4 (1) In formula (1), [A] is represented by the following formula (2-1), where a in formula (2-1) is an integer of 0 to 3; [B] is represented by the following formula (2-2), where b in formula (2-2) is an integer of 0 to 3, and c is an integer of 2 to 5; wherein the sum of the values ​​of a and b is 1 to 3; in formula (1), [A] and [B] are interchangeable; [C] is represented by the following formula (3-1), where d in formula (3-1) is an integer of 0 to 2; [D] is represented by the following formula (3-2), where e in formula (3-2) is an integer of 0 to 2, and f is an integer of 2 to 5; wherein the sum of the values ​​of d and e is 1 or 2; in formula (1), [C] and [D] are interchangeable; R 4 is a branched terminal group having 3 to 30 carbon atoms and is represented by the following formula (4); L in the formula (4) represents an integer of 0 to 6; Y in the formula (4) 1 and Y 2 Each is independently a hydrocarbon group having only one primary hydroxyl group and may contain an ether oxygen atom; Y in formula (4) 3 is a hydrocarbon group having only one primary hydroxyl group, which may contain an ether oxygen atom, or a hydrogen atom; R 1 For R 4 The terminal groups may be the same or different and are branched terminal groups having 3 to 30 carbon atoms as represented by formula (4), organic groups having 1 to 30 carbon atoms having an ether oxygen atom at the terminal bonded to [A] or [B], or hydroxyl groups; z represents 1 or 2; R 2 is a perfluoropolyether chain; 2 or 3 R 2 They may be partly or completely the same, or they may be different; R 3 is a divalent linking group represented by the following formula (5); y1 in the formula (5) is an integer of 1 to 3, and y2 is an integer of 1 to 3; the dotted line in the formula (5) that is bonded to the oxygen atom on the left side represents the bond with R 1 The dotted line that is bonded to the methylene on the right side indicates the bond with R 4 When z is 2, two R 3 They can be the same or different.

2. The fluorinated ether compound according to claim 1, wherein R in the formula (1) is 4 The formula (4) is any one of the following formulas (6-1) to (6-3); In formula (6-1), g represents an integer of 1 to 6; X 1 and X 2 It is expressed by formula (7); X 1 With X 2 It can be the same or different; In formula (6-2), h represents an integer of 0 to 6; i and j each independently represent an integer of 1 to 6; X 3 and X 4 is represented by a hydrogen atom or formula (7); X 3 With X 4 It can be the same or different; In formula (6-3), k represents an integer of 0 to 6; p, q and r each independently represent an integer of 1 to 6; X 5 , X 6 and X 7 is represented by a hydrogen atom or formula (7); X 5 , X 6 and X 7 They may be different from each other, or partly or completely the same; In formula (7), s represents an integer of 2 to 6, and t represents 1 or 2.

3. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 It is a branched terminal group having 3 to 30 carbon atoms represented by the above formula (4).

4. The fluorinated ether compound according to claim 2, wherein R in the formula (1) 1 and R 4 Both are branched terminal groups in any of the formulae (6-1) to (6-3).

5. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 -[B]-[A]-, and -[C]-[D]-R 4 same.

6. The fluorinated ether compound according to claim 1 or 2, wherein z in the formula (1) is 2, and two R 3 The atoms contained in the R 2 Symmetrical configuration.

7. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 It is represented by the following formula (8): In formula (8), u represents an integer of 2 to 6, v represents 0 or 1; R 5 is any one of a hydrogen atom, an alkyl group which may have a substituent not including a hydroxyl group, and an organic group having at least one double bond or triple bond; in, The alkyl group and the organic group may be linear or branched.

8. The fluorinated ether compound according to claim 7, wherein R in the formula (8) 5 It is an alkyl group having 1 to 6 carbon atoms.

9. The fluorine-containing ether compound according to claim 7, wherein R in the formula (8) 5 It is an alkyl group having 1 to 6 carbon atoms and having a substituent, and the substituent is a fluoro group or a cyano group.

10. The fluorine-containing ether compound according to claim 7, wherein R in the formula (8) 5 It is any one of an organic group having 6 to 12 carbon atoms having an aromatic hydrocarbon, an organic group having 3 to 10 carbon atoms having an aromatic heterocycle, an alkenyl group having 2 to 8 carbon atoms, and an alkynyl group having 3 to 8 carbon atoms.

11. The fluorine-containing ether compound according to claim 7, wherein R in the formula (8) 5 It is one group selected from methyl, ethyl, n-propyl, isopropyl, 2,2,2-trifluoroethyl, 2,2,3,3,3-pentafluoropropyl, 2,2,2,2,2,2-hexafluoroisopropyl, 2-cyanoethyl, 3-cyanopropyl, 4-cyanobutyl, phenyl, methoxyphenyl, cyanophenyl, phenethyl, thienylethyl, N-methylpyrazolylmethyl, allyl, 3-butenyl, 4-pentenyl, propargyl, 3-butynyl, and 4-pentynyl.

12. The fluorine-containing ether compound according to claim 7, wherein R in the formula (8) 5 A hydrogen atom.

13. The fluorinated ether compound according to claim 1 or 2, wherein two or three R in the formula (1) are 2 Each is independently a perfluoropolyether chain represented by the following formula (9); -(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 -(9) In formula (9), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; in, w2, w3, w4, w5 are not all 0 at the same time; w1 and w6 represent CF 2 The average value of the number of, and each independently represents 1 to 3; for (CF 2 O)、(CF 2 CF 2 O)、(CF 2 CF 2 CF 2 O)、(CF 2 CF 2 CF 2 CF 2 O) is not particularly limited in the order of arrangement.

14. The fluorinated ether compound according to claim 1 or 2, wherein two or three R 2 Each independently represents any one of the perfluoropolyether chains selected from the group consisting of the following formulae (10-1) to (10-4); -CF 2 -(OCF 2 CF 2 ) l -(OCF 2 ) m -OCF 2 -(10-1) In formula (10-1), l and m represent the average degree of polymerization, l represents 0.1 to 20, and m represents 0 to 20; -CF 2 CF 2 -(OCF 2 CF 2 CF 2 ) n -OCF 2 CF 2 -(10-2) In formula (10-2), n represents the average degree of polymerization and is 0.1 to 15; -CF 2 CF 2 CF 2 -(OCF 2 CF 2 CF 2 CF 2 ) o -OCF 2 CF 2 CF 2 -(10-3) In formula (10-3), o represents the average degree of polymerization and represents 0.1 to 10; -(CF 2 ) w7 -O-(CF 2 CF 2 CF 2 O) w8 -(CF 2 CF 2 O) w9 -(CF 2 ) w10 -(10-4) In formula (10-4), w8 and w9 represent the average degree of polymerization, and each independently represents 0.1 to 20; w7 and w10 represent CF 2 The average value of the number and each independently represents 1 to 2.

15. The fluorine-containing ether compound according to claim 1 or 2, which has a number average molecular weight in the range of 500 to 10,000.

16. A lubricant for a magnetic recording medium, It is characterized in that Contains the fluorine-containing ether compound according to claim 1 or 2.

17. A magnetic recording medium, It is characterized in that A magnetic recording medium having at least a magnetic layer, a protective layer and a lubricating layer arranged in sequence on a substrate. The lubricating layer comprises the fluorine-containing ether compound according to claim 1 or 2. 18 . The magnetic recording medium according to claim 17 , wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm.

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