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

Abstract

A fluorine-containing ether compound represented by formula (1). R1-CH2-R2 [-CH2-R3-CH2-R2] x-CH2-R4 (R1 and R4 are terminal groups including two or three polar groups, each polar group is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are bonded to each other via a linking group including a carbon atom to which no polar group is bonded; x is 1-2; r2 is a perfluoropolyether chain; and R3 is represented by formula (3-1) or (3-2). > # 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. 2022-083156 filed in Japan on May 20, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] In order to improve the recording density of a magnetic recording and reproducing device, development of a magnetic recording medium suitable for high recording density has been carried out.

[0004] In the past, as a magnetic recording medium, there is a recording layer formed on a substrate, and a protective layer of carbon or the like is formed on the recording layer. The protective layer protects the information recorded in the recording layer and improves the sliding property of the magnetic head. In addition, the protective layer covers the recording layer to prevent the metal contained in the recording layer from being corroded by environmental substances.

[0005] However, the durability of the magnetic recording medium cannot be fully obtained by only providing a protective layer on the recording layer. Therefore, a lubricant is applied to the surface of the protective layer to form a lubricating layer with a thickness of about 0.5 to 3 nm. The lubricating layer improves the durability and protective power of the protective layer and prevents the intrusion of pollutants into the interior of the magnetic recording medium.

[0006] 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.

[0007] 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 perfluoroether chains.

[0008] 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 perfluoroether chains.

[0009] Patent Documents 5, 6 and 7 disclose fluorinated ether compounds having a backbone 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 backbone via methylene groups (-CH2-).

[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 Summary of the invention

[0019] Problems to be solved by the invention

[0020] In magnetic recording and reproducing devices, it is required to further reduce the flying height of the magnetic head. Therefore, it is required to further reduce the thickness of the protective layer and / or lubricating layer in the magnetic recording medium.

[0021] However, if the thickness of the lubricating layer is thin, the coating property of the lubricating layer is reduced, and the chemical resistance and the floating stability of the magnetic head tend to be reduced. Therefore, a lubricating layer with excellent chemical resistance and good floating stability of the magnetic head is required even if the thickness is thin.

[0022] 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 has excellent chemical resistance and good floating stability of the magnetic head even if the thickness is thin and can be suitably used as a material for a lubricant for a magnetic recording medium.

[0023] Another object of the present invention is to provide a lubricant for a magnetic recording medium comprising the fluorinated ether compound of the present invention, which can form a lubricating layer having excellent chemical resistance and good flying stability of a magnetic head even though the lubricating layer is thin.

[0024] Another object of the present invention is to provide a magnetic recording medium having a lubricating layer containing the fluorinated ether compound of the present invention and having excellent chemical resistance and flying stability of a magnetic head.

[0025] Means for solving problems

[0026] The present invention includes the following aspects.

[0027] A first aspect of the present invention provides the following fluorine-containing ether compound.

[0028] [1] A fluorine-containing ether compound characterized by being represented by the following formula (1).

[0029] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1)

[0030] (In formula (1), R 1 and R 4 Each independently represents an end group containing 2 or 3 polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms bonded to the polar groups are bonded to each other via a linking group containing a carbon atom not bonded to a polar group; x represents an integer of 1 to 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 (3-1) or (3-2); when x is 2, two R 3 They can be the same or different.)

[0031]

[0032] (In formula (3-1), a represents an integer of 2 to 4; y1 represents an integer of 1 to 3; y2 represents an integer of 1 to 3; at least one of y1 and y2 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 4 The side methylene bond is bonded to the bond.)

[0033] (In formula (3-2), y3 represents an integer of 1 to 3; y4 represents an integer of 1 to 3; at least one of y3 and y4 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 4 The side methylene bond is bonded to the bond.)

[0034] The fluorine-containing ether compound according to the first aspect of the present invention preferably has the features described in the following [2] to [9]. It is also preferred that any two or more of the features described in the following [2] to [9] are combined.

[0035] [2] The fluorinated ether compound according to [1], wherein in the above formula (1), -R 1 and -R 4Each independently represents any one of the following formulae (4-1) to (4-3).

[0036]

[0037] (In formula (4-1), b is an integer of 1 to 2, and c is an integer of 0 to 3; X in formula (4-1) is an alkenyl group, an alkynyl group, or a polar group; when b is 1, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X.)

[0038] (In formula (4-2), d is an integer of 1 to 3, e is an integer of 0 to 1, and f is an integer of 0 to 3; X in formula (4-2) is an alkenyl group, an alkynyl group, or a polar group; when e is 0, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X.)

[0039] (In formula (4-3), g is an integer of 0 to 1, h is an integer of 1 to 3, and i is an integer of 1 to 3; X in formula (4-3) is an alkenyl group, an alkynyl group, or a polar group; when g is 0, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X.)

[0040] [3] The fluorinated ether compound according to [2], wherein in the above formulas (4-1) to (4-3), X is any one of a hydroxyl group, a group having an amide bond, a cyano group, and -CH=CH2.

[0041] [4] The fluorinated ether compound according to any one of [1] to [3], wherein x in the above formula (1) is 1, and R 1 With R 4 Same, 2 R 2 same.

[0042] [5] The fluorinated ether compound according to any one of [1] to [3], wherein x in the formula (1) is 2, and R 1 With R 4 Same, 3 Rs 2 same.

[0043] [6] The fluorinated ether compound according to [5], wherein the two R 3 The atoms contained in the R are located in the center of the molecular chain structure. 2 are symmetrically configured.

[0044] [7] The fluorinated ether compound according to any one of [1] to [6], wherein two or three R in the formula (1) are 2Each is independently a perfluoropolyether chain represented by the following formula (5).

[0045] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(5)

[0046] (In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein 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 (5).)

[0047] [8] The fluorinated ether compound according to any one of [1] to [6], 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 (6-1) to (6-4).

[0048] -CF2-(OCF2CF2) j -(OCF2) k -OCF2-(6-1)

[0049] (In formula (6-1), j and k represent average polymerization degrees, j represents 0.1 to 20, and k represents 0 to 20.)

[0050] -CF2CF2-(OCF2CF2CF2) l -OCF2CF2-(6-2)

[0051] (In formula (6-2), l represents the average degree of polymerization and is 0.1 to 15.)

[0052] -CF2CF2CF2-(OCF2CF2CF2CF2) m -OCF2CF2CF2-(6-3)

[0053] (In formula (6-3), m represents the average degree of polymerization and is 0.1 to 10.)

[0054] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9-(CF2) w10 -(6-4)

[0055] (In formula (6-4), w8 and w9 represent the average degree of polymerization, and each independently represents 0.1 to 20; w7 and w10 represent the average value of the number of CF2, and each independently represents 1 to 2.)

[0056] [9] The fluorinated ether compound according to any one of [1] to [8], wherein the number average molecular weight is within the range of 500 to 10,000.

[0057] A second aspect of the present invention provides the following lubricant for a magnetic recording medium.

[0058]

[10] A lubricant for a magnetic recording medium, comprising the fluorine-containing ether compound according to any one of [1] to [9].

[0059] A third aspect of the present invention provides the following magnetic recording medium.

[0060]

[11] 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,

[0061] The lubricating layer contains the fluorine-containing ether compound described in any one of [1] to [9].

[0062] The magnetic recording medium according to the third aspect of the present invention preferably has the feature described in the following

[12] .

[0063]

[12] The magnetic recording medium according to

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

[0064] Effects of the Invention

[0065] 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.

[0066] Since the lubricant for a magnetic recording medium of the present invention contains the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer having excellent chemical resistance and good flying stability of a magnetic head even if the lubricating layer is thin.

[0067] The magnetic recording medium of the present invention has a lubricating layer comprising a fluorinated ether compound of the present invention, so the chemical resistance and the floating stability of the magnetic head are good. Therefore, the magnetic recording medium of the present invention has excellent durability and reliability. In addition, the magnetic recording medium of the present invention has a lubricating layer having excellent chemical resistance and good floating stability of the magnetic head, so the thickness of the protective layer and / or the lubricating layer can be made thin. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention. DETAILED DESCRIPTION

[0069] The inventors etc. have repeatedly carried out in-depth research as shown below in order to solve the above-mentioned problem. 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, preferably used the fluorine-containing ether compound with polar groups such as hydroxyl. The polar group included by the fluorine-containing ether compound is combined with the active point on the protective layer, so that the adhesion of the lubricating layer to the protective layer is improved. For the fluorine-containing ether compound in the past, the terminal in the chain structure is configured with a polar group. In addition, when the fluorine-containing ether compound has a plurality of perfluoropolyether chains, the adjacent perfluoropolyether chains are also configured with a polar group.

[0070] However, when a thin lubricating layer is formed on a protective layer using a conventional lubricant, it is difficult to realize a lubricating layer having good resistance to chemical substances and good flying stability of a magnetic head.

[0071] The reason for this is that the fluorine-containing ether compound contained in the lubricating layer contains polar groups which are not adsorbed to active sites existing in large numbers on the protective layer.

[0072] If there are polar groups that are not adsorbed to the active points on the protective layer in the fluorinated ether compound contained in the lubricating layer, the lubricant in the lubricating layer becomes bulky, and the coating state of the lubricating layer on the protective layer becomes uneven. Therefore, if there are a large number of polar groups that are not adsorbed to the active points on the protective layer in the fluorinated ether compound contained in the lubricating layer, the chemical resistance of the lubricating layer and the floating stability of the magnetic head are likely to become insufficient.

[0073] Therefore, the present inventors have focused on the bonding behavior of polar groups contained in fluorinated ether compounds with active sites on the protective layer and have conducted intensive studies to realize fluorinated ether compounds that are less likely to generate polar groups that do not participate in bonding with active sites on the protective layer.

[0074] As a result, the present inventors have found that secondary hydroxyl groups contained in divalent linking groups disposed between adjacent perfluoropolyether chains among polar groups contained in a fluorinated ether compound are less likely to participate in bonding with active sites on a protective layer.

[0075] Therefore, the inventors etc. will be configured in the secondary hydroxyl that the divalent linking group that the adjacent perfluoropolyether interchain that the fluorine-containing ether compound has is comprised is chemically modified and is changed into primary hydroxyl.And then, use the fluorine-containing ether compound that has been changed and formed lubricating layer.As a result, it is known that chemical substance resistance and the floating stability of magnetic head improve.It is inferred that this is because, by changing the secondary hydroxyl that the above-mentioned divalent linking group comprises into primary hydroxyl, thereby becomes the fluorine-containing ether compound that is not easy to produce the hydroxyl that is combined with the active point that exists on the protective layer.

[0076] Further, the inventors have repeatedly conducted in-depth research and found that as long as a fluorinated ether compound having two or three perfluoropolyether chains is prepared, a specific divalent linking group having only one primary hydroxyl group is configured between adjacent perfluoropolyether chains, and specific terminal groups are configured at both ends. The divalent linking group has a side chain portion that branches from the chain structure of the fluorinated ether compound and performs ether bonding. The side chain portion is configured with a primary hydroxyl group at the front end, and has a linking group containing a methylene group (-CH2-) that combines the carbon atom bound to the primary hydroxyl group and the oxygen atom bound to the carbon atom of the chain structure. In addition, the terminal group contains two or three polar groups, each of which is bound to a different carbon atom, and the carbon atoms bound to the above-mentioned polar groups are bound to each other via a linking group containing a carbon atom that is not bound to a polar group.

[0077] Such fluorinated ether compounds are not easy to generate polar groups that are not combined with the functional groups (active sites) present on the protective layer due to the following reasons. Therefore, it is estimated that the fluorinated ether compounds can form a lubricating layer with excellent chemical resistance and floating stability of the magnetic head.

[0078] That is, the above-mentioned divalent linking group has only one primary hydroxyl group, and there is a gap in the steric space compared with the case where the secondary hydroxyl group is replaced by the primary hydroxyl group. In addition, for the above-mentioned fluorine-containing ether compound, in the side chain portion of the above-mentioned divalent linking group, the carbon atom to which the primary hydroxyl group is configured at the front end is combined with the oxygen atom combined with the carbon atom of the chain structure through a linking group containing a methylene group (-CH2-). Therefore, the distance between the primary hydroxyl group and the carbon atom of the chain structure of the above-mentioned divalent linking group is appropriate. According to these circumstances, the primary hydroxyl group of the above-mentioned divalent linking group is not easy to be hindered from combining with the active point on the protective layer by the bulky part of the fluorine-containing ether compound such as the tertiary carbon combined with the side chain portion of the divalent linking group. Moreover, the primary hydroxyl group is generally freer to move than the secondary hydroxyl group. Therefore, the primary hydroxyl group of the above-mentioned divalent linking group can move spontaneously relative to the active point on the protective layer. Therefore, the primary hydroxyl group of the above-mentioned divalent linking group can easily form a combination with the active point on the protective layer.

[0079] In addition, when the above-mentioned fluorine-containing ether compound has three perfluoropolyether chains, there are two of the above-mentioned divalent linking groups. In this case, a perfluoropolyether chain is disposed between two adjacent divalent linking groups. Therefore, the distance between the primary hydroxyl groups of the two adjacent divalent linking groups will not become too close. Therefore, for the above-mentioned fluorine-containing ether compound, the primary hydroxyl group of the above-mentioned divalent linking group is not easy to be hindered from combining with the active point on the protective layer by the primary hydroxyl group of other divalent linking groups contained in the fluorine-containing ether compound. In addition, for the above-mentioned fluorine-containing ether compound, the primary hydroxyl groups of the two adjacent divalent linking groups are not easy to agglomerate with each other.

[0080] Furthermore, for the above-mentioned fluorine-containing ether compound, a perfluoropolyether chain is respectively arranged between the above-mentioned divalent linking group and the two terminal groups. Therefore, the distance between the primary hydroxyl group of the above-mentioned divalent linking group and the two or three polar groups of each terminal group will not become too close. As a result, the primary hydroxyl group of the above-mentioned divalent linking group is not easy to be hindered from binding with the active point on the protective layer by the polar group of the terminal group. In addition, since the distance between the primary hydroxyl group of the above-mentioned divalent linking group and the polar group of the terminal group is appropriate, the primary hydroxyl group of the above-mentioned divalent linking group and the polar group of the terminal group are not easy to agglomerate.

[0081] Furthermore, in the above-mentioned fluorine-containing ether compound, the above-mentioned divalent linking group has a side chain portion having only one primary hydroxyl group and branching from the chain structure of the fluorine-containing ether compound to form an ether bond. In the above-mentioned fluorine-containing ether compound, since the side chain portion of the above-mentioned divalent linking group branches from the chain structure to form an ether bond, for example, the flexibility of the side chain portion is better than the case where the carbon atom of the side chain portion is directly bonded to the carbon atom of the chain structure. Therefore, the primary hydroxyl group of the side chain portion of the above-mentioned divalent linking group can easily form a bond with the active point on the protective layer.

[0082] In addition, for the above-mentioned fluorine-containing ether compound, the 2 or 3 polar groups possessed by each terminal group are each combined with different carbon atoms, and the carbon atoms to which the above-mentioned polar groups are combined are combined with each other via a connecting group containing a carbon atom that is not combined with a polar group. Therefore, the 2 or 3 polar groups possessed by each terminal group are all considered to be an orientation that can be closely fitted on the protective layer. Thus, the 2 or 3 polar groups possessed by each terminal group are not easy to agglomerate, and can easily form a combination with an active point on the protective layer.

[0083] As described above, in the above-mentioned fluorine-containing ether compound, the side chain part of the above-mentioned divalent linking group has good flexibility, and the primary hydroxyl groups of the side chain part can move spontaneously, and are not easy to aggregate, and are not easy to be blocked from binding with the active point on the protective layer by the primary hydroxyl groups of other divalent linking groups, the polar groups of the terminal groups, and the bulky parts in the fluorine-containing ether compound. In addition, in the above-mentioned fluorine-containing ether compound, the two or three polar groups of each terminal group are oriented to be closely attached to the protective layer.

[0084] According to these situations, for the above-mentioned fluorinated ether compound, it is difficult to produce the polar group that is not combined with the functional group (active point) existing on the protective layer. As a result, it is inferred that the above-mentioned fluorinated ether compound can form a lubricating layer that has good adhesion to the protective layer, is difficult to introduce pollutants, has excellent chemical resistance, and the floating stability of the magnetic head is good. Further, the inventors etc. confirmed that by using the lubricant that comprises the above-mentioned fluorinated ether compound, a lubricating layer that is good in chemical resistance and the floating stability of the magnetic head can be formed, thereby thought of the present invention.

[0085] Below, the preferred example of fluorine-containing ether compound of the present invention, magnetic recording medium lubricant and magnetic recording medium is described in detail.It should be noted that the present invention is not limited only to the embodiment shown below.The present invention can add, omit, replace, change number, amount, position, ratio, material, formation etc. without exceeding the scope of the purpose of the present invention.

[0086] [Fluorinated ether compounds]

[0087] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

[0088] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1)

[0089] (In formula (1), R 1 and R 4 Each independently represents an end group containing 2 or 3 polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms bonded to the polar groups are bonded to each other via a linking group containing a carbon atom not bonded to a polar group; x represents an integer of 1 to 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 3is a divalent linking group represented by the following formula (3-1) or (3-2); when x is 2, two R 3 They can be the same or different.)

[0090]

[0091] (In formula (3-1), a represents an integer of 2 to 4. y1 represents an integer of 1 to 3; y2 represents an integer of 1 to 3; at least one of y1 and y2 is 1; the dotted line bonded to the oxygen atom on the left represents the bond to R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 4 The side methylene bond is bonded to the bond.)

[0092] (In formula (3-2), y3 represents an integer of 1 to 3; y4 represents an integer of 1 to 3; at least one of y3 and y4 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 4 The side methylene bond is bonded to the bond.)

[0093] The fluorinated ether compound of this embodiment has R having only one primary hydroxyl group as shown in formula (1). 3 One or two divalent linking groups shown, and R 2 The skeleton of the chain structure is composed of two or three perfluoropolyether chains (hereinafter sometimes referred to as PFPE chains) connected via methylene groups. R 2 The PFPE chain shown, R 1 and R 4 The terminal groups shown to contain two or three polar groups are each bonded via a methylene group.

[0094] In the fluorinated ether compound represented by formula (1), x represents an integer of 1 to 2. Since x in the fluorinated ether compound represented by formula (1) is an integer of 1 to 2, the number of polar groups in the molecule is appropriate. That is, the number of polar groups contained in the fluorinated ether compound represented by formula (1) is 5 to 8. Therefore, the fluorinated ether compound represented by formula (1), for example, can form a lubricating layer having good adhesion to the protective layer compared to the case where x is 0. In addition, the fluorinated ether compound represented by formula (1), for example, can prevent the interaction between polar groups in the molecule compared to the case where x is 3 or more, and the polar groups possessed by the fluorinated ether compound are less likely to agglomerate with each other.

[0095] (R 3 The divalent linking group shown

[0096] For the fluorine-containing ether compound represented by formula (1), since x is 1 or 2, R2 Each PFPE chain shown is connected via -CH2-R 3 In the fluorine-containing ether compound represented by formula (1), x R 3 Each has no secondary hydroxyl group and only one primary hydroxyl group. 3 One or more R 3 Compared with the case with secondary hydroxyl groups, R 3 The degree of freedom of the contained hydroxyl groups is high, R 3 The hydroxyl groups in the protective layer are easy to interact with the active points on the protective layer. Therefore, when a lubricating layer is formed on the protective layer using a lubricant containing a fluorinated ether compound represented by formula (1), a suitable interaction occurs between the lubricating layer and the protective layer. Therefore, the fluorinated ether compound represented by formula (1) can form a lubricating layer that has good adhesion to the protective layer and good chemical resistance with sufficient coverage even if the thickness is thin. In addition, the lubricating layer is 3 The contained primary hydroxyl groups are easy to interact with the active sites on the protective layer, so R 3 The primary hydroxyl groups contained in R 3 R on both sides 2 The PFPE chain shown is not easy to float from the protective layer. As a result, the distance from the magnetic head is appropriate and the lubricating layer with good floating stability of the magnetic head is formed.

[0097] R 3 is a divalent linking group represented by formula (3-1) or (3-2). 3 The ends of both sides of R are oxygen atoms. 3 The ends of both sides are connected with R 2 The bound methylene group is bound via an ether bond.

[0098] R 3 The main chain part (-O(CH2) y -CH-(CH2) y -O- (y in the formula is an integer of 1 to 3. At least one of the two y is 1.)), and a side chain portion branched from the main chain portion to form an ether bond. The side chain portion is arranged in R 3 The terminal oxygen atoms on both sides of the main chain part are branched from the main chain part through 1 to 3 methylene groups. The side chain part has a primary hydroxyl group at the front end, and has a connecting group containing a methylene group (-CH2-) that connects the carbon atom to which the primary hydroxyl group is bonded and the oxygen atom (etheric oxygen atom) bonded to the carbon atom of the main chain part.

[0099] In R 3On the carbon atom forming the main chain portion, -(CH2) in formula (3-1) is bonded as a side chain portion via an ether bond. a OH or -CH2CH2OCH2CH2OH in formula (3-2). In this embodiment, by R 3 The side chain part of R 3 The carbon atoms forming part of the main chain are ether-bonded, so that, for example, R 3 The carbon atoms that form the main chain and R 3 Compared with the case where the carbon atom of the side chain is directly bonded to 3 The side chain portion of R has good flexibility. 3 The side chain portion of R has a chain structure of appropriate length including a linking group. 3 The side chain part of the protective layer can easily interact with the active sites.

[0100] In formula (3-1), a is an integer of 2 to 4. If a is 2 or more, then R 3 The primary hydroxyl group contained in the PFPE chain in the fluorinated ether compound as R 3 The carbon atoms that form the main chain and R 3 The distance between bulky sites such as tertiary carbons to which the side chains of the R 3 The contained primary hydroxyl groups are easy to move freely. As a result, the primary hydroxyl groups in formula (3-1) are easy to adhere to the protective layer, and the lubricating layer containing the fluorinated ether compound represented by formula (1) is not easy to float from the protective layer. In addition, if a is 4 or less, -(CH2) in formula (3-1) a The flexibility of OH is maintained. a OH can move flexibly, and a is preferably 2 to 3, and most preferably 2.

[0101] In formula (3-1), 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 1. Since at least one of y1 and y2 is 1, it becomes a fluorine-containing ether compound that is easy to manufacture. In order to maintain the overall flexibility of the divalent linking group represented by formula (3-1), y2 when only y1 is 1 (or y1 when only y2 is 1) among y1 and y2 is 3 or less, preferably 2 or less. For y1 and y2, in order to maintain the overall flexibility of the divalent linking group represented by formula (3-1), it is more preferable that y1 is 1 and y2 is 1.

[0102] In the formula (3-2), -CH2CH2OCH2CH2OH contains an ether bond (-O-). Therefore, -CH2CH2OCH2CH2OH in the formula (3-2) ensures flexibility in movement.

[0103] In formula (3-2), y3 is an integer of 1 to 3, and y4 is an integer of 1 to 3. At least one of y3 and y4 is 1. Since at least one of y3 and y4 is 1, it becomes a fluorine-containing ether compound that is easy to manufacture. In order to maintain the overall flexibility of the divalent linking group shown in formula (3-2), among y3 and y4, when only y3 is 1, y4 (or y3 when only y4 is 1) is 3 or less, preferably 2 or less. For y3 and y4, in order to maintain the overall flexibility of the divalent linking group shown in formula (3-2), it is more preferable that y3 is 1 and y4 is 1.

[0104] In formula (1), when x is 2, the two R 3 They can be the same or different. 3 Under the same conditions, it is preferred to be a fluorine-containing ether compound that is easy to manufacture. 3 Same” means two R 3 The atoms contained in the R are located in the center of the molecular chain structure. 2 That is, when x is 2, the fluorine-containing ether compound represented by formula (1) preferably has two R 3 Formula (3-1), 2 R 3 The a in formula (3-1) is the same, and the two R 3 In the formula (3-1), y1 and y2 are relative to R arranged in the center of the chain structure. 2 The symmetric value of the fluorinated ether compound, or 2 R 3 is formula (3-2), and 2 R 3 In the formula (3-2), y3 and y4 are relative to R arranged in the center of the chain structure. 2 The symmetric values ​​of fluorinated ether compounds. For example, in R 1 Side R 3 It is represented by formula (3-1), where y1 is 1, y2 is 2, and R 4 Side R 3 As shown in formula (3-1), when y1 in formula (3-1) is 2 and y2 is 1, and the value of a in formula (3-1) is the same, the two R 3 In addition, for example, in R 1 Side R 3 It is represented by formula (3-2), where y3 is 1, y4 is 2, and R 4 Side R 3 It is represented by formula (3-2). When y3 is 2 and y4 is 1 in formula (3-2), two R 3 same.

[0105] (R2 PFPE chain shown)

[0106] In the fluorinated ether compound represented by formula (1), the number of (x+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.

[0107] In the fluorinated ether compound represented by formula (1), 2 or 3 R 2 Some or all of them may be the same, or they may be different. (x+1) R 2 It is preferred that all of them are the same. This is because the coating state of the protective layer with the fluorinated ether compound becomes uniform, and a lubricating layer with better adhesion is obtained. 2 Two or more R 2 The same means (x+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 same repeating unit structure and different average polymerization degrees are also included. 2 .

[0108] As R 2 The PFPE chain shown in the above-mentioned example includes a PFPE chain formed of a polymer or copolymer of a perfluoroalkylene oxide, etc. Examples of the perfluoroalkylene oxide include perfluoroformaldehyde, perfluoroethylene oxide, perfluoropropylene oxide, perfluoroisopropylene oxide, and perfluorobutylene oxide.

[0109] The (x+1) R in formula (1) 2 Preferably, the PFPE chains are each independently a polymer or copolymer derived from a perfluoroalkylene oxide and represented by the following formula (5).

[0110] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(5)

[0111] (In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein 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 (5).)

[0112] In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20, preferably 0 to 15, and more preferably 0 to 10. They may be 1 to 8, 2 to 6, 3 to 5, and the like.

[0113] In formula (5), w1 and w6 are average values ​​of the number of CF2, and each independently represents 1 to 3. In the PFPE chain represented by formula (5), w1 and w6 are determined by the structure of the repeating unit arranged at the end of the chain structure, etc.

[0114] In formula (5), (CF2O), (CF2CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) are repeating units. There is no particular restriction on the arrangement order of the repeating units in formula (5). In addition, there is no particular restriction on the number of types of repeating units in formula (5).

[0115] The (x+1) R in formula (1) 2 Preferably, each independently is any one selected from the group consisting of PFPE chains represented by the following formulae (6-1) to (6-4).

[0116] If (x+1) R 2 Each independently represents any one of the PFPE chains represented by formulae (6-1) to (6-4), and a lubricating layer having good lubricity is obtained. 2 When each is independently selected from any one of the PFPE chains represented by formulas (6-1) to (6-4), 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 to the protective layer is not easily agglomerated on the protective layer, and a thinner lubricating layer can be formed with a sufficient coverage. In addition, the fluorinated ether compound has moderate softness, so that a lubricating layer with better chemical resistance can be formed.

[0117] -CF2-(OCF2CF2) j -(OCF2) k -OCF2-(6-1)

[0118] (In formula (6-1), j and k represent average polymerization degrees, j represents 0.1 to 20, and k represents 0 to 20.)

[0119] -CF2CF2-(OCF2CF2CF2) l -OCF2CF2-(6-2)

[0120] (In formula (6-2), l represents the average degree of polymerization and is 0.1 to 15.)

[0121] -CF2CF2CF2-(OCF2CF2CF2CF2) m -OCF2CF2CF2-(6-3)

[0122] (In formula (6-3), m represents the average degree of polymerization and is 0.1 to 10.)

[0123] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(6-4)

[0124] (In formula (6-4), w8 and w9 represent the average degree of polymerization, and each independently represents 0.1 to 20; w7 and w10 represent the average value of the number of CF2, and each independently represents 1 to 2.)

[0125] In formula (6-1), there is no particular restriction on the arrangement order of (OCF2CF2) and (OCF2) as repeating units. In formula (6-1), the number j of (OCF2CF2) and the number k of (OCF2) may be the same or different. The PFPE chain shown in formula (6-1) may be a polymer of (OCF2CF2). In addition, the PFPE chain shown in formula (6-1) may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF2CF2) and (OCF2).

[0126] In formulas (6-1) to (6-3), since j representing the average degree of polymerization is 0.1 to 20, k is 0 to 20, l is 0.1 to 15, and m is 0.1 to 10, a fluorine-containing ether compound is obtained that can obtain a lubricating layer having good lubricity. In addition, in formulas (6-1) to (6-3), since j and k representing the average degree of polymerization are 20 or less, l is 15 or less, and m is 10 or less, the viscosity of the fluorine-containing ether compound does not become too high, and a lubricant containing the fluorine-containing ether compound is easy to apply and is preferred. In order to obtain a fluorine-containing ether compound that can easily wet and spread on the protective layer and easily obtain a lubricating layer having a uniform film thickness, j, k, l, and m representing the average degree of polymerization are preferably 1 to 10, more preferably 1.5 to 8, and further preferably 2 to 7.

[0127] In formula (6-4), there is no particular restriction on the arrangement order of (CF2CF2CF2O) and (CF2CF2O) as repeating units. In formula (6-4), the number w8 of (CF2CF2CF2O) representing the average degree of polymerization and the number w9 of (CF2CF2O) may be the same or different. Formula (6-4) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF2CF2CF2O) and (CF2CF2O).

[0128] In formula (6-4), w8 and w9 representing the average degree of polymerization are each independently 0.1 to 20, preferably 1 to 15, and more preferably 1 to 10. w7 and w10 in formula (6-4) are average values ​​representing the number of CF2, and each independently represents 1 to 2. w7 and w10 are determined based on the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (6-4).

[0129] (R 1 and R 4 terminal groups shown)

[0130] In the fluorine-containing ether compound represented by formula (1), R 1 and R 4 The terminal groups shown are independently 2 or 3 polar groups, each of which is combined with different carbon atoms, and the carbon atoms combined with the polar groups are combined with each other via the connecting group of the carbon atoms that are not combined with the polar groups. Therefore, the 2 or 3 polar groups are all oriented to be closely attached to the protective layer, and when a lubricant containing the fluorinated ether compound shown in formula (1) is used to form a lubricating layer on the protective layer, a suitable interaction occurs between the lubricating layer and the protective layer. As a result, the high adhesion to the protective layer is obtained, and a lubricating layer with good chemical resistance and floating stability of the magnetic head can be formed.

[0131] Examples of the polar group include a hydroxyl group (-OH), a group having an amide bond (-NR 5 COR 6 or-CONR 7 R 8 ; R 5 , R 6 , R 7 and R 8 Each is independently a hydrogen atom or an organic group. ), cyano (-CN), amino (-NR 9 R 10 ; R 9 and R 10 Each independently represents a hydrogen atom or an organic group. ), carboxyl (-COOH), formyl (-(C=O)H), carbonyl (-CO-), sulfonyl (-SO3H), etc. In addition, the "group having an amide bond" includes both a group bonded to the carbon atom constituting the amide bond (e.g., formamide (-C(=O)NH2)) and a group bonded to the nitrogen atom constituting the amide bond (e.g., acetamide (-NHC(=O)CH3)) as shown in the above formula. In the group having an amide bond, the above R 5 With R 6 can be combined with each other to form a ring, the above R 7 With R 8 The above R in the group having an amide bond may be bonded to each other to form a ring. 5 , R 6 , R 7 and R 8 Preferably, they are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group.

[0132] R 1 and R 4 It is preferred that at least one selected from a hydroxyl group, a group having an amide bond, and a cyano group be included as a polar group. 1 and R 4 A fluorinated ether compound having at least one selected from a hydroxyl group, a group having an amide bond, and a cyano group, when a lubricating layer is formed on the protective layer using a lubricant containing the fluorinated ether compound, a more suitable interaction occurs between the lubricating layer and the protective layer. 1 and R 4 The two or three polar groups contained in each of the above may be partially or entirely the same, or may be entirely different. In order to form a fluorine-containing ether compound capable of forming a lubricating layer having better adhesion to the protective layer, R 1 and R 4 Preferably, each contains at least one hydroxyl group as a polar group.

[0133] In the fluorine-containing ether compound represented by formula (1), R 1The polar groups contained in R 4 The total number of polar groups included is 4 to 6. Since the total number is 4 or more, the lubricating layer containing the fluorinated ether compound has high adhesion (closeness) to the protective layer. In addition, since the total number is 6 or less, in the magnetic recording medium having the lubricating layer containing the fluorinated ether compound, the fluorinated ether compound can be prevented from being too polar and being attached to the magnetic head as a foreign matter (stain) by pick-up.

[0134] R 1 The number of polar groups contained and R 4 The number of polar groups contained is preferably the same. 1 and R 4 Each contains 2 polar groups, or R 1 and R 4 Each of the two polar groups contains three polar groups. In this case, the lubricant containing the fluorine-containing ether compound is well-balanced and closely attached to the protective layer. Therefore, it is easy to obtain a lubricating layer with high coverage, chemical resistance and better floating stability of the magnetic head.

[0135] R 1 and R 4 The terminal groups shown are preferably terminal groups each having 2 or 3 polar groups and having 4 to 18 carbon atoms, and more preferably terminal groups having 4 to 11 carbon atoms. When the number of carbon atoms is within the above range, the ratio of the number of carbon atoms to the number of polar groups becomes appropriate, resulting in a fluorine-containing ether compound having appropriate molecular polarity.

[0136] R 1 and R 4 The terminal groups shown in the formula (a) are preferably oxygen atoms at the ends of the adjacent methylene groups. 1 and R 4 The fluorinated ether compound is bonded to adjacent methylene groups via ether bonds to form a fluorinated ether compound having moderate hardness. Therefore, the fluorinated ether compound applied on the protective layer is not easily aggregated on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage.

[0137] R 1 and R 4 Specifically, the terminal groups shown are preferably each independently any one of the following formulae (4-1) to (4-3).

[0138]

[0139] (In formula (4-1), b is an integer of 1 to 2, and c is an integer of 0 to 3; X in formula (4-1) is an alkenyl group, an alkynyl group, or a polar group; when b is 1, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X.)

[0140] (In formula (4-2), d is an integer of 1 to 3, e is an integer of 0 to 1, and f is an integer of 0 to 3; X in formula (4-2) is an alkenyl group, an alkynyl group, or a polar group: when e is 0, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X.)

[0141] (In formula (4-3), g is an integer of 0 to 1, h is an integer of 1 to 3, and i is an integer of 1 to 3; X in formula (4-3) is an alkenyl group, an alkynyl group, or a polar group; when g is 0, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X.)

[0142] X in formula (4-1) to (4-3) is an alkenyl group, an alkynyl group, or a polar group. When X is an alkenyl group or an alkynyl group, a π-π interaction with the protective layer occurs. When X is a polar group, an interaction with the protective layer occurs through its polarity. Therefore, the fluorinated ether compound having the terminal group shown in formula (4-1) to (4-3) can form a lubricating layer having good adhesion due to the interaction with the protective layer, thereby obtaining good chemical resistance and floating stability of the magnetic head.

[0143] Examples of the alkenyl group include -CH=CH2, -CH=CHR 11 (R 11 Is an organic group. ), -CR 12 =CHR 13 (R 12 , R 13 Is an organic group. ), -CR 14 =CR 15 R 16 (R 14 , R 15 , R 16 is an organic group. ) etc. 11 ~R 16 The organic groups shown are preferably hydrocarbon groups having 1 to 3 carbon atoms. When X in formulas (4-1) to (4-3) is an alkenyl group, it is preferably -CH=CH2. -CH=CH2 has a suitable large volume. Therefore, the lubricating layer containing a fluorinated ether compound having an end group in which X is -CH=CH2 is easy to be in a state where the height of the fluorinated ether compound on the protective layer is low, and the floating stability of the magnetic head is good.

[0144] Examples of the alkynyl group include -C≡CH, -C≡CR 17 (R 17 is an organic group. ) etc. 17 The organic group shown is preferably a hydrocarbon group having 1 to 3 carbon atoms. When X in formulae (4-1) to (4-3) is an alkynyl group, in order to obtain a terminal group having a suitably large bulkiness, -C≡CH is preferred.

[0145] Examples of the polar group include a hydroxyl group (-OH), a group having an amide bond (-NR 5 COR 6 or-CONR 7 R 8 ; R 5 , R 6 , R 7 and R 8 Each is independently a hydrogen atom or an organic group. ), cyano (-CN), amino (-NR 9 R 10 ; R 9 and R 10 Each independently represents a hydrogen atom or an organic group. ), carboxyl (-COOH), formyl (-(C=O)H), carbonyl (-CO-), sulfo (-SO3H), etc. It should be noted that the "group having an amide bond" includes both a group bonded to the carbon atom constituting the amide bond and a group bonded to the nitrogen atom constituting the amide bond as shown in the above formula. Specific examples of the "group having an amide bond" include the above R 1 and R 4 Specific examples are given by way of example of the polar groups contained therein.

[0146] When X in formulae (4-1) to (4-3) is a polar group, it is preferably any one selected from a hydroxyl group, a group having an amide bond, and a cyano group in order to form a fluorinated ether compound capable of forming a lubricating layer having good adhesion to the protective layer.

[0147] In the above, X in formulas (4-1) to (4-3) is preferably any one of a hydroxyl group, a group having an amide bond, a cyano group, and -CH=CH2. This is because it is a fluorine-containing ether compound that can form a lubricating layer with a higher coverage, better chemical resistance, and better floating stability of the magnetic head.

[0148] In the terminal group shown in formula (4-1), b is an integer of 1 to 2. When b is 1, X is a polar group, and formula (4-1) has two polar groups. In this case, since formula (4-1) has two polar groups, a lubricating layer with good adhesion to the protective layer can be formed. When b is 2, X can be any one of an alkenyl group, an alkynyl group, and a polar group. When X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X. When b is 2 and X is an alkenyl group or an alkynyl group, formula (4-1) also has two polar groups. Therefore, a lubricating layer with good adhesion to the protective layer can be formed. In addition, since X is an alkenyl group or an alkynyl group, the adhesion of the terminal group to the protective layer is not impaired, and a lubricating layer with good chemical resistance and floating stability of the magnetic head can be formed through the π-π interaction between X and the protective layer. In addition, when b is 2 and X is a polar group, formula (4-1) has three polar groups. Therefore, a lubricating layer having excellent adhesion to the protective layer can be formed.

[0149] c in formula (4-1) is an integer of 0 to 3. For the terminal group shown in formula (4-1), even if X in formula (4-1) is a polar group, since the distance between X and the secondary hydroxyl group in formula (4-1) is not too close, the polar group in formula (4-1) is not easy to agglomerate. In the case where X in formula (4-1) is a polar group, in order to make the distance between X and the secondary hydroxyl group in formula (4-1) more appropriate, c is preferably an integer greater than 1. For the terminal group shown in formula (4-1), since c is an integer less than 3, the mobility of X in formula (4-1) does not become too high, and each polar group possessed by the terminal group can be fully adhered to the protective layer. c is more preferably an integer less than 2.

[0150] In the terminal group represented by formula (4-2), d is an integer of 1 to 3. When e is 0, X is a polar group. Since d is an integer greater than 1, when e is 0, the distance between X and the secondary hydroxyl group in formula (4-2) becomes appropriate, and even if X is a polar group, the polar group in formula (4-2) is not easy to agglomerate. In addition, when e is 1, since the distance between the secondary hydroxyl groups in formula (4-2) does not become too close, the secondary hydroxyl groups in formula (4-2) are not easy to agglomerate. For the terminal group represented by formula (4-2), since d is an integer less than 3, the mobility of the terminal group represented by formula (4-2) does not become too high, and each polar group possessed by the terminal group can be fully adhered to the protective layer. d is preferably an integer less than 2.

[0151] In the terminal group shown in formula (4-2), e is an integer of 0 to 1. When e is 0, X is a polar group, and formula (4-2) has two polar groups. In this case, since formula (4-2) has two polar groups, a lubricating layer with good adhesion to the protective layer can be formed. When e is 1, X can be any one of an alkenyl group, an alkynyl group, and a polar group. When X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X. When e is 1 and X is an alkenyl group or an alkynyl group, formula (4-2) also has two polar groups. Therefore, a lubricating layer with good adhesion to the protective layer can be formed. In addition, since X is an alkenyl group or an alkynyl group, the adhesion of the terminal group to the protective layer is not impaired, and a lubricating layer with good chemical resistance and floating stability of the magnetic head can be formed through the π-π interaction between X and the protective layer. In addition, when e is 1 and X is a polar group, formula (4-2) has three polar groups. Therefore, a lubricating layer having excellent adhesion to the protective layer can be formed.

[0152] f in formula (4-2) is an integer of 0 to 3. For the terminal group shown in formula (4-2), even if X in formula (4-2) is a polar group, the distance between X and the secondary hydroxyl group in formula (4-2) will not be too close, so the polar group in formula (4-2) is not easy to agglomerate. In the case where X in formula (4-2) is a polar group, the distance between X and the secondary hydroxyl group in formula (4-2) becomes more appropriate, so f is preferably greater than 1. In addition, when e is 0, even if f is 0, the distance between X as a polar group and the secondary hydroxyl group in formula (4-2) becomes appropriate through d methylene groups. In the case where e is 0, if f is greater than 1, the distance between X as a polar group and the secondary hydroxyl group in formula (4-2) becomes more appropriate through d+f methylene groups, so it is preferred. In the terminal group represented by formula (4-2), since f is an integer of 3 or less, the mobility of X in formula (4-2) does not become too high, and each polar group of the terminal group can sufficiently adhere to the protective layer.

[0153] In the terminal group shown in formula (4-3), g is an integer of 0 to 1. When g is 0, X is a polar group, and formula (4-3) has two polar groups. In this case, since formula (4-3) has two polar groups, a lubricating layer with good adhesion to the protective layer can be formed. When g is 1, X can be any one of an alkenyl group, an alkynyl group, and a polar group. When X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X. When g is 1 and X is an alkenyl group or an alkynyl group, formula (4-3) also has two polar groups. Therefore, a lubricating layer with good adhesion to the protective layer can be formed. In addition, since X is an alkenyl group or an alkynyl group, the adhesion of the terminal group to the protective layer is not impaired, and a lubricating layer with good chemical resistance and floating stability of the magnetic head can be formed through the π-π interaction between X and the protective layer. In addition, when g is 1 and X is a polar group, formula (4-3) has three polar groups. Therefore, a lubricating layer having excellent adhesion to the protective layer can be formed.

[0154] In the terminal group represented by formula (4-3), h is an integer of 1 to 3. Since h is greater than 1, when g is 1, the distance between the secondary hydroxyl groups in formula (4-3) will not become too close. Therefore, the secondary hydroxyl groups in formula (4-3) are not easy to agglomerate. For the terminal group represented by formula (4-3), since h is an integer less than 3, the mobility of the terminal group represented by formula (4-3) will not become too high, and each polar group possessed by the terminal group can be fully adhered to the protective layer. h is preferably an integer less than 2.

[0155] i in formula (4-3) is an integer of 1 to 3. For the terminal group shown in formula (4-3), since i is greater than 1, even if X in formula (4-3) is a polar group, the distance between X and the secondary hydroxyl group in formula (4-3) will not become too close. Therefore, the polar group in formula (4-3) is not easy to agglomerate. When g is 1, h is less than 2, and X is a polar group, in order to make the distance between X and the secondary hydroxyl group in formula (4-3) more appropriate, i is preferably greater than 2. For the terminal group shown in formula (4-3), since i is an integer less than 3, the mobility of X in formula (4-3) will not become too high, and each polar group possessed by the terminal group can be fully adhered to the protective layer.

[0156] In the fluorine-containing ether compound represented by formula (1), R 1 With R 4 They can be the same or different. 1 With R 4 If the coating state of the protective layer with the fluorinated ether compound is the same, the coating state of the protective layer with the fluorinated ether compound becomes more uniform, and a lubricating layer with better adhesion can be formed.

[0157] In the fluorine-containing ether compound represented by formula (1), R1 and R 4 The type of the terminal group shown above can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, etc.

[0158] In the fluorine-containing ether compound represented by formula (1), x is preferably 1, and R 1 With R 4 Same, 2 R 2 The reason is that it is a fluorine-containing ether compound that is easy to synthesize.

[0159] In the fluorine-containing ether compound represented by formula (1), x is preferably 2, and R 1 With R 4 Same, 3 Rs 2 The reason is that it is a fluorine-containing ether compound that is easy to synthesize. Further, when x is 2, preferably 2 R 3 The atoms contained in the R are located in the center of the molecular chain structure. 2 The reason is that it is easier to synthesize fluorine-containing ether compounds. 3 The atoms contained in the R are located in the center of the molecular chain structure. 2 and are symmetrically configured", such as in R 3 As described in the instructions.

[0160] Specifically, the fluorine-containing ether compound represented by the formula (1) is preferably any one of the compounds represented by the following formulae (1A) to (1O), (2A) to (2O), (3A) and (3B).

[0161] When the compound represented by formula (1) is any of the compounds represented by the following formulas (1A) to (1O), (2A) to (2O), (3A), and (3B), the raw materials are easy to obtain and a lubricating layer with good chemical resistance and magnetic head floating stability can be formed.

[0162] In the compounds represented by the following formulae (1A) to (1O), (2A) to (2O), (3A), and (3B), Rf1 and Rf2 representing a PFPE chain each have the following structure. That is, Rf1 is a PFPE chain represented by the above formula (6-1), and Rf2 is a PFPE chain represented by the above formula (6-2). It should be noted that j and k in Rf1 representing a PFPE chain in formulae (1G) to (1I), (1L), (1M), (1O), (2G) to (2I), (2L), (2M), and (2O), and l in Rf2 representing a PFPE chain in formulae (1A) to (1F), (1J), (1K), (1N), (2A) to (2F), (2J), (2K), (2N), (3A), and (3B) are values ​​representing an average degree of polymerization and are not necessarily limited to integers.

[0163]

[0164] The compounds represented by the following formulae (1A) to (1O), (2A) to (2O), (3A), and (3B) are all R 1 With R 4 same.

[0165] The compounds represented by the following formulae (1A) to (1O), (2A) to (2O), (3A), and (3B) all have 2 or 3 R 2 same.

[0166] In the compounds represented by the following formulae (1A) to (1O), (3A), and (3B), x is 1.

[0167] In all of the compounds represented by the following formulae (2A) to (2O), x is 2.

[0168] The two R of the compounds represented by the following formulas (2A) to (2O) are 3 same.

[0169] The compounds represented by the following formulae (1A) to (1O), (2A) to (2O), and (3A) are all R 3 It is represented by formula (3-1), wherein y1 is 1 and y2 is 1. The R of the compound represented by the following formula (3B) 3 Expressed by formula (3-2), y3 in formula (3-2) is 1 and y4 is 1.

[0170] The compounds represented by the following formulae (1A) to (1O) and (2A) to (2O) are all R 3 As expressed by formula (3-1), a is 2.

[0171] The compounds represented by the following formulas (1A) to (1F), (1J), (1K), (1N), (2A) to (2F), (2J), (2K), (2N), (3A), and (3B) are all R 2 The PFPE chain shown is formula (6-2).

[0172] The compounds represented by the following formulae (1G) to (1I), (1L), (1M), (1O), (2G) to (2I), (2L), (2M), and (2O) are all R 2 The PFPE chain shown is formula (6-1).

[0173] In the compound represented by the following formula (1A), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 1, c is 1, and X is a hydroxyl group.

[0174] In the compound represented by the following formula (1B), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 1, c is 2, and X is a hydroxyl group.

[0175] In the compound represented by the following formula (1C), R in the formula (1) is 1 and R 4 It is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 1, and X is a hydroxyl group.

[0176] In the compound represented by the following formula (1D), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 2, and X is a hydroxyl group.

[0177] In the compound represented by the following formula (1E), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-2), wherein d in the formula (4-2) is 1, e is 0, f is 1, and X is a hydroxyl group.

[0178] In the compound represented by the following formula (1F), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-2), wherein d in the formula (4-2) is 1, e is 1, f is 1, and X is a hydroxyl group.

[0179] In the compound represented by the following formula (1G), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g in the formula (4-3) is 0, i is 1, and X is a hydroxyl group.

[0180] In the compound represented by the following formula (1H), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g in the formula (4-3) is 0, i is 3, and X is a hydroxyl group.

[0181] In the compound represented by the following formula (1I), R 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g is 1, h is 1, i is 2, and X is a hydroxyl group.

[0182] In the compound represented by the following formula (1J), R in the formula (1) is 1 and R 4It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 0, and X is -CH=CH2.

[0183] In the compound represented by the following formula (1K), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-2), wherein d is 1, e is 1, f is 1, and X is -CH=CH2.

[0184] In the compound represented by the following formula (1L), R in the formula (1) is 1 and R 4 It is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 2, and X is -CN.

[0185] In the compound represented by the following formula (1M), R in the formula (1) is 1 and R 4 It is the terminal group represented by the above formula (4-2), wherein d in the formula (4-2) is 2, e is 1, f is 1, and X is a hydroxyl group.

[0186] In the compound represented by the following formula (1N), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g is 1, h is 2, i is 1, and X is a hydroxyl group.

[0187] In the compound represented by the following formula (1O), R in the formula (1) is 1 and R 4 It is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 1, and X is -NHCOCH3.

[0188] In the compound represented by the following formula (2A), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 1, c is 1, and X is a hydroxyl group.

[0189] In the compound represented by the following formula (2B), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 1, c is 2, and X is a hydroxyl group.

[0190] In the compound represented by the following formula (2C), R in the formula (1) is 1 and R 4 It is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 1, and X is a hydroxyl group.

[0191] In the compound represented by the following formula (2D), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 2, and X is a hydroxyl group.

[0192] In the compound represented by the following formula (2E), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-2), wherein d in the formula (4-2) is 1, e is 0, f is 1, and X is a hydroxyl group.

[0193] In the compound represented by the following formula (2F), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-2), wherein d in the formula (4-2) is 1, e is 1, f is 1, and X is a hydroxyl group.

[0194] In the compound represented by the following formula (2G), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g in the formula (4-3) is 0, i is 1, and X is a hydroxyl group.

[0195] In the compound represented by the following formula (2H), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g in the formula (4-3) is 0, i is 3, and X is a hydroxyl group.

[0196] In the compound represented by the following formula (2I), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g is 1, h is 1, i is 2, and X is a hydroxyl group.

[0197] In the compound represented by the following formula (2J), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 0, and X is -CH=CH2.

[0198] In the compound represented by the following formula (2K), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-2), wherein d is 1, e is 1, f is 1, and X is -CH=CH2.

[0199] In the compound represented by the following formula (2L), R in the formula (1) is 1 and R 4is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 2, and X is -CN. R in the formula (1) of the compound represented by the following formula (2M) 1 and R 4 It is the terminal group represented by the above formula (4-2), wherein d in the formula (4-2) is 1, e is 0, f is 1, and X is -CN.

[0200] In the compound represented by the following formula (2N), R in the formula (1) is 1 and R 4 It is a terminal group represented by the above formula (4-3), wherein g is 1, h is 2, i is 1, and X is a hydroxyl group.

[0201] In the compound represented by the following formula (2O), R in the formula (1) is 1 and R 4 It is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 2, c is 1, and X is -NHCOCH3.

[0202] In the compound represented by the following formula (3A), R in the formula (1) is 1 and R 4 is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 1, c is 2, and X is a hydroxyl group. 3 It is a linking group represented by formula (3-1), wherein a in formula (3-1) is 4.

[0203] In the compound represented by the following formula (3B), R in the formula (1) is 1 and R 4 is the terminal group represented by the above formula (4-1), wherein b in the formula (4-1) is 1, c is 2, and X is a hydroxyl group. 3 It is a linking group represented by formula (3-2).

[0204]

[0205] (Rf21a in formula (1A) is represented by formula (1AF); in Rf21a, l1a represents an average degree of polymerization, which is 0.1 to 15; l1a in two Rf21a in formula (1A) may be the same or different.)

[0206] (Rf21b in formula (1B) is represented by formula (1BF); in Rf21b, l1b represents an average degree of polymerization, which is 0.1 to 15; l1b in two Rf21b in formula (1B) may be the same or different.)

[0207]

[0208] (Rf21c in formula (1C) is represented by formula (1CF); in Rf21c, l1c represents an average degree of polymerization, which is 0.1 to 15; l1c in two Rf21c in formula (1C) may be the same or different.)

[0209] (Rf21d in formula (1D) is represented by formula (1DF); in Rf21d, l1d represents an average degree of polymerization, which is 0.1 to 15; l1d in two Rf21d in formula (1D) may be the same or different.)

[0210]

[0211] (Rf21e in formula (1E) is represented by formula (1EF); in Rf21e, l1e represents an average degree of polymerization, which is 0.1 to 15; l1e in two Rf21e in formula (1E) may be the same or different.)

[0212] (Rf21f in formula (1F) is represented by formula (1FF); in Rf21f, l1f represents an average degree of polymerization, which is 0.1 to 15; l1f in two Rf21f in formula (1F) may be the same or different.)

[0213]

[0214] (Rf11g in formula (1G) is represented by formula (1GF); in Rf11g, j1g and k1g represent average polymerization degrees, j1g represents 0.1 to 20, and k1g represents 0 to 20; in formula (1G), j1g and k1g in two Rf11g may be the same or different.)

[0215] (Rf11h in formula (1H) is represented by formula (1HF); in Rf11h, j1h and k1h represent average polymerization degrees, j1h represents 0.1 to 20, and k1h represents 0 to 20; in formula (1H), j1h and k1h in two Rf11h may be the same or different.)

[0216]

[0217] (Rf11i in formula (1I) is represented by formula (1IF); in Rf11i, j1i and k1i represent average polymerization degrees, j1i represents 0.1 to 20, and k1i represents 0 to 20; in formula (1I), j1i and k1i in two Rf11i may be the same or different.)

[0218] (Rf21j in formula (1J) is represented by formula (1JF); in Rf21j, l1j represents an average degree of polymerization, which is 0.1 to 15; l1j in two Rf21j in formula (1J) may be the same or different.)

[0219]

[0220] (Rf21k in formula (1K) is represented by formula (1KF); in Rf21k, l1k represents an average degree of polymerization, which is 0.1 to 15; l1k in two Rf21k in formula (1K) may be the same or different.)

[0221] (Rf111 in formula (1L) is represented by formula (1LF); in Rf111, j11 and k11 represent average polymerization degrees, j11 represents 0.1 to 20, and k11 represents 0 to 20; in formula (1L), j11 and k11 in two Rf111 may be the same or different.)

[0222]

[0223] (Rf11m in formula (1M) is represented by formula (1MF); in Rf11m, j1m and k1m represent average polymerization degrees, j1m represents 0.1 to 20, and k1m represents 0 to 20; in formula (1M), j1m and k1m in two Rf11m may be the same or different.)

[0224] (Rf21n in formula (1N) is represented by formula (1NF); in Rf21n, l1n represents an average degree of polymerization, which is 0.1 to 15; l1n in two Rf21n in formula (1N) may be the same or different.)

[0225]

[0226] (Rf11o in formula (1O) is represented by formula (1OF); in Rf11o, j1o and k1o represent average polymerization degrees, j1o represents 0.1 to 20, and k1o represents 0 to 20; in formula (1O), j1o and k1o in two Rf11o may be the same or different.)

[0227] (Rf22a in formula (2A) is represented by formula (2AF); in Rf22a, l2a represents an average degree of polymerization, which is 0.1 to 15; l2a in the three Rf22a in formula (2A) may be different from each other, or may be partially or entirely the same.)

[0228]

[0229] (Rf22b in formula (2B) is represented by formula (2BF); in Rf22b, l2b represents an average degree of polymerization, which is 0.1 to 15; l2b in the three Rf22b in formula (2B) may be different from each other, or may be partially or entirely the same.)

[0230] (Rf22c in formula (2C) is represented by formula (2CF); in Rf22c, l2c represents an average degree of polymerization, which is 0.1 to 15; l2c in the three Rf22c in formula (2C) may be different from each other, or may be partially or entirely the same.)

[0231]

[0232] (Rf22d in formula (2D) is represented by formula (2DF); in Rf22d, l2d represents an average degree of polymerization, which is 0.1 to 15; l2d in the three Rf22d in formula (2D) may be different from each other, or may be partially or entirely the same.)

[0233] (Rf22e in formula (2E) is represented by formula (2EF); in Rf22e, l2e represents an average degree of polymerization, which is 0.1 to 15; l2e in the three Rf22e in formula (2E) may be different from each other, or may be partially or entirely the same.)

[0234]

[0235] (Rf22f in formula (2F) is represented by formula (2FF); in Rf22f, l2f represents an average degree of polymerization, which is 0.1 to 15; l2f in the three Rf22f in formula (2F) may be different from each other, or may be partially or entirely the same.)

[0236] (Rf12g in formula (2G) is represented by formula (2GF); in Rf12g, j2g and k2g represent average polymerization degrees, j2g represents 0.1 to 20, and k2g represents 0 to 20; in formula (2G), j2g and k2g in the three Rf12g may be different from each other, or may be partially or entirely the same.)

[0237]

[0238] (Rf12h in formula (2H) is represented by formula (2HF); in Rf12h, j2h and k2h represent average polymerization degrees, j2h represents 0.1 to 20, and k2h represents 0 to 20; in formula (2H), j2h and k2h in three Rf12h may be different from each other, or may be partially or entirely the same.)

[0239] (Rf12i in formula (2I) is represented by formula (2IF); in Rf12i, j2i and k2i represent average polymerization degrees, j2i represents 0.1 to 20, and k2i represents 0 to 20; in formula (2I), j2i and k2i in the three Rf12i may be different from each other, or may be partially or entirely the same.)

[0240]

[0241] (Rf22j in formula (2J) is represented by formula (2JF); in Rf22j, l2j represents an average degree of polymerization, which is 0.1 to 15; l2j in the three Rf22j in formula (2J) may be different from each other, or may be partially or entirely the same.)

[0242] (Rf22k in formula (2K) is represented by formula (2KF); in Rf22k, l2k represents an average degree of polymerization, which is 0.1 to 15; l2k in the three Rf22k in formula (2K) may be different from each other, or may be partially or entirely the same.)

[0243]

[0244] (Rf121 in formula (2L) is represented by formula (2LF); in Rf121, j21 and k21 represent average polymerization degrees, j21 represents 0.1 to 20, and k21 represents 0 to 20; in formula (2L), j21 and k21 in three Rf121 may be different from each other, or may be partially or entirely the same.)

[0245] (Rf12m in formula (2M) is represented by formula (2MF); in Rf12m, j2m and k2m represent average polymerization degrees, j2m represents 0.1 to 20, and k2m represents 0 to 20; in formula (2M), j2m and k2m in three Rf12m may be different from each other, or may be partially or entirely the same.)

[0246]

[0247] (Rf22n in formula (2N) is represented by formula (2NF); in Rf22n, l2n represents an average degree of polymerization, which is 0.1 to 15; l2n in the three Rf22n in formula (2N) may be different from each other, or may be partially or entirely the same.)

[0248] (Rf12o in formula (2O) is represented by formula (2OF); in Rf12o, j2o and k2o represent average polymerization degrees, j2o represents 0.1 to 20, and k2o represents 0 to 20; in formula (2O), j2o and k2o in the three Rf12o may be different from each other, or may be partially or entirely the same.)

[0249]

[0250] (Rf23a in formula (3A) is represented by formula (3AF); in Rf23a, l3a represents an average degree of polymerization, which is 0.1 to 15; l3a in two Rf23a in formula (3A) may be the same or different.)

[0251] (Rf23b in formula (3B) is represented by formula (3BF); in Rf23b, l3b represents an average degree of polymerization, which is 0.1 to 15; l3b in two Rf23b in formula (3B) may be the same or different.)

[0252] 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 is 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 used as a lubricant, the number average molecular weight of the fluorinated ether compound is preferably 5,000 or less.

[0253] 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 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.

[0254] 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.

[0255] 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.

[0256] "Manufacturing method"

[0257] 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, for example, by the production method described below.

[0258] [First Manufacturing Method]

[0259] When producing a compound wherein x in the formula (1) is 1, the following production method can be used.

[0260] <2 R 2 Same situation>

[0261] (First reaction)

[0262] In the manufacturing formula (1), the two R 2 In the case of a compound having the same perfluoropolyether chain, a 2 The corresponding perfluoropolyether chain has fluoro compounds with hydroxymethyl (-CH2OH) groups at both ends. Then, a protecting group such as a tetrahydropyranyl (THP) group is introduced into the hydroxyl group of the hydroxymethyl group at one end of the fluoro compound to obtain an intermediate compound 1-1.

[0263] (Second reaction)

[0264] Next, the terminal hydroxyl group of the intermediate compound 1-1 is fused with a 3 Thus, a halogen compound having an epoxy group corresponding to R in the center is produced. 3 The linking group corresponding to the main chain portion of R is bonded to R via methylene groups at both ends. 2 The corresponding perfluoropolyether chain intermediate compound 1-2. In the intermediate compound 1-2, 3 In the linking group corresponding to the main chain portion of , one secondary hydroxyl group generated by the reaction of the terminal hydroxyl group of the intermediate compound 1-1 and the epoxy group of the halogen compound is arranged.

[0265] As above with R 3 The main chain part corresponds to the halogen compound of the epoxy group, for example, in R 3 It is represented by formula (3-1), when y1 and y2 in formula (3-1) are both 1, or R 3 In the case where both y3 and y4 in the formula (3-2) are 1, epibromohydrin or epichlorohydrin can be used.

[0266] <2 R 2 Different situations>

[0267] In the manufacturing formula (1), the two R 2 In the case of compounds having different perfluoropolyether chains, the following reactions are carried out as the first reaction and the second reaction.

[0268] (First reaction)

[0269] With 2 R 2 The first reaction under the same conditions is carried out in the same manner to produce 1 Side R 2 The first intermediate compound 1-1-1 of the corresponding perfluoropolyether chain. 2 The first reaction under the same conditions is carried out in the same manner to produce 4 Side R 2 The corresponding second intermediate compound of the perfluoropolyether chain is 1-1-2.

[0270] (Second reaction)

[0271] The terminal hydroxyl group of the first intermediate compound 1-1-1 is fused with a 3 The terminal hydroxyl group of the second intermediate compound 1-1-2 is reacted with a halogen compound having an epoxy group corresponding to the main chain portion of R. 3 The compound obtained by reacting a halogen compound corresponding to the epoxy group in the main chain portion of the first intermediate compound 1-1-1 is reacted with the terminal hydroxyl group of the first intermediate compound 1-1-1.

[0272] Thus, the manufacturing has a central 3 The linking group corresponding to the main chain portion of 1 Side R 2 The corresponding perfluoropolyether chain has a methylene group bonded to R 4 Side R 2 The corresponding perfluoropolyether chain, intermediate compound 1-2-2. 2 In different intermediate compounds 1-2-2, in the presence of R 3 In the linking group corresponding to the main chain portion of , a secondary hydroxyl group generated by the reaction of the terminal hydroxyl group of the first intermediate compound 1-1-1 or the terminal hydroxyl group of the second intermediate compound 1-1-2 with the epoxy group of the halogen compound is arranged.

[0273] (Third reaction)

[0274] Then, in 2 R 2 The same intermediate compound 1-2 (or 2 R 2Different intermediate compounds 1-2-2) will be configured to become R 3 The secondary hydroxyl groups in the main chain are chemically modified and converted into primary hydroxyl groups.

[0275] Make it equal to R 3 The structure corresponding to the side chain part and the halogen compound with a protective group introduced into the terminal primary hydroxyl group and the intermediate compound 1-2 (or intermediate compound 1-2-2) and R 3 The secondary hydroxyl group of the connecting group corresponding to the main chain portion is reacted to produce the intermediate compound 1-3.

[0276] As for R 3 The side chain portion corresponds to the structure and a halogen compound with a protecting group is introduced into the terminal primary hydroxyl group, for example, in R 3 In the case represented by formula (3-1), BnO(CH2) can be used. a Br (Bn represents a benzyl group. a is an integer of 2 to 4.) etc. As the above-mentioned halogen compound, for example, in R 3 In the case of the formula (3-2), BnO(CH2)2O(CH2)2Br (Bn represents a benzyl group) or the like can be used.

[0277] (Fourth reaction)

[0278] Next, the protecting groups (e.g., THP groups) bonded to both ends of the intermediate compound 1-3 are removed by a known method to obtain the intermediate compound 1-4. For example, when a THP group is introduced as a protecting group, the THP group can be removed by a method using an acid such as a mixed solution of hydrogen chloride and methanol.

[0279] <R 1 With R 4 Same situation>

[0280] (Fifth Reaction)

[0281] In formula (1), R 1 With R 4 In the same case, the terminal hydroxyl group of the intermediate compound 1-4 is connected to the 1 - the corresponding group (= with R 4 - corresponding group) of the epoxy compound. Thus, the 3 The two ends of the linker corresponding to the main chain of 2 The two ends of the chain structure of the backbone have R 1 - the corresponding group (= with R 4 -corresponding group) to the intermediate compound 1-5.

[0282] <R 1 With R 4 Different situations>

[0283] In formula (1), R 1 With R 4 In other cases, the following reaction is performed as the fifth reaction.

[0284] (Fifth Reaction)

[0285] In the process of making a terminal hydroxyl group of the intermediate compound 1-4 and a 1 - The epoxy group of the epoxy compound corresponding to the group is reacted to make the other terminal hydroxyl group react with the epoxy group of the epoxy compound corresponding to R 4 - the epoxy group of the epoxy compound corresponding to the group. Or by reacting a terminal hydroxyl group of the intermediate compound 1-4 with a 4 - The epoxy group of the epoxy compound corresponding to the group is reacted to make the other terminal hydroxyl group react with the epoxy group of the epoxy compound corresponding to R 1 - the epoxy group of the epoxy compound corresponding to the group. Thus, the 3 The two ends of the linker corresponding to the main chain of 2 One end of the chain structure skeleton has a connection with R through a methylene group. 1 - corresponding group, having a terminal end connected to R via a methylene group 4 - the intermediate compound 1-5-2 of the corresponding group.

[0286] The compound used in the fifth reaction has the same R as in formula (1). 1 - the corresponding group (or 4 - corresponding group) can be prepared by, for example, making the fluorinated ether compound have R 1 (or R 4 ) and a compound having an epoxy group selected from epichlorohydrin, epibromohydrin, 2-bromoethyl oxirane, and allyl glycidyl ether. Such an epoxy compound can be synthesized by oxidizing an unsaturated bond, or a commercially available product can be purchased and used.

[0287] In the fifth reaction, R 1 - the corresponding group (or 4 - corresponding group) can also be combined with R 1 - the corresponding group (or 4-corresponding group) is protected with an appropriate protecting group and then reacted with the intermediate compound 1-4. Examples of the protecting group for protecting the hydroxyl group of the epoxy compound include a tetrahydropyranyl (THP) group and a methoxymethyl (MOM) group.

[0288] (Sixth Reaction)

[0289] Finally, all the protecting groups introduced into the intermediate compound 1-5 (or intermediate compound 1-5-2) are removed by conventionally known methods. 3 In the case where a Bn group is introduced as a protecting group into the terminal primary hydroxyl group in the corresponding structure, the protection can be removed by reacting it with palladium carbon (Pd / C) under acidic conditions. 1 and R 4 In the case where a THP group is introduced as a protecting group into the corresponding structure, the THP group can be removed together with the Bn group by reacting the intermediate compound 1-5 (or intermediate compound 1-5-2) with R 1 and R 4 When a MOM group is introduced as a protecting group into each of the corresponding structures, it can be removed by, for example, a method using an acid such as a mixed solution of hydrogen chloride and methanol.

[0290] By carrying out the above steps, a compound wherein x is 1 in the formula (1) can be produced.

[0291] [Second manufacturing method]

[0292] When producing a compound wherein x in the formula (1) is 2, the following production method can be used.

[0293] <2 R 3 When the main chain parts are the same>

[0294] (First reaction)

[0295] Prepare the three R in formula (1) 2 The middle R 2 The corresponding perfluoropolyether chain has hydroxymethyl (-CH2OH) groups at both ends of the fluorine-based compound. Then, the hydroxyl groups of the hydroxymethyl groups at both ends of the fluorine-based compound are connected to a fluorine-based compound having a structure similar to R 3 The main chain portion of the epoxy group corresponding to the halogen compound is reacted. 2 The corresponding intermediate compound 2-1 has epoxy groups at both ends of the perfluoropolyether chain.

[0296] As above with R 3 The main chain part corresponds to the halogen compound of the epoxy group, for example, R 3 It is represented by formula (3-1), when y1 and y2 in formula (3-1) are both 1, or in R 3 In the case where both y3 and y4 in the formula (3-2) are 1, epibromohydrin or epichlorohydrin can be used.

[0297] <2 R 3 When the main chain part is different >

[0298] (First reaction)

[0299] In the manufacturing formula (1), the two R 3 In the case of compounds having different main chain parts, the following reaction is performed as the first reaction.

[0300] Make the R 2 The corresponding perfluoropolyether chain has a hydroxyl group of a hydroxymethyl group of a fluorine compound having a hydroxymethyl group (-CH2OH) and a hydroxymethyl group having R 1 Side R 3 After the halogen compound of the epoxy group corresponding to the main chain part of the reaction, it is purified. Thus, the 2 One end of the corresponding perfluoropolyether chain has 1 Side R 3 Next, the intermediate compound obtained is reacted with a hydroxyl group corresponding to the main chain portion of R 4 Side R 3 The main chain portion corresponds to the epoxy group of the halogen compound.

[0301] Thus, we can obtain 2 One end of the corresponding perfluoropolyether chain has 1 Side R 3 The main chain portion corresponds to an epoxy group, and the other end has an epoxy group corresponding to R 4 Side R 3 The main chain portion corresponds to the epoxy group of the intermediate compound 2-1-2.

[0302] The intermediate compound 2-1-2 can also be prepared by reacting the hydroxyl group of the hydroxymethyl group of the fluorine compound with a 4 Side R 3 A compound obtained by reacting a halogen compound with an epoxy group corresponding to the main chain portion of the present invention and then purifying the compound, and a compound having R 1 Side R 3The method is to prepare the epoxy group corresponding to the main chain part by reacting a halogen compound.

[0303] As above with R 1 Side R 3 (or R 4 Side R 3 ) corresponding to the main chain part of the epoxy halogen compound, for example, in R 3 It is represented by formula (3-1), when y1 and y2 in formula (3-1) are both 1, or in R 3 In the case where both y3 and y4 in the formula (3-2) are 1, epibromohydrin or epichlorohydrin can be used.

[0304] As above with R 1 Side R 3 The main chain part corresponds to the halogen compound of the epoxy group, for example, in R 1 Side R 3 In the formula (3-1), when y1 is 1 and y2 is 2, or when R 1 Side R 3 In the formula (3-2), when y3 is 1 and y4 is 2, 2-(2-chloroethyl)ethylene oxide and 2-(2-bromoethyl)ethylene oxide can be used. 1 Side R 3 In the formula (3-1), when y1 is 1 and y2 is 3, or when R 1 Side R 3 In the case where y3 is 1 and y4 is 3 and represented by the formula (3-2), (3-chloropropyl)ethylene oxide and (3-bromopropyl)ethylene oxide can be used.

[0305] As above with R 4 Side R 3 The main chain part corresponds to the halogen compound of the epoxy group, for example, in R 4 Side R 3 In the formula (3-1), when y1 is 2 and y2 is 1, or when R 4 Side R 3 In the formula (3-2), when y3 is 2 and y4 is 1, 2-(2-chloroethyl)ethylene oxide and 2-(2-bromoethyl)ethylene oxide can be used. 4 Side R 3 In the formula (3-1), when y1 is 3 and y2 is 1, or when R 4 Side R 3In the case where y3 is 3 and y4 is 1 and represented by the formula (3-2), (3-chloropropyl)ethylene oxide and (3-bromopropyl)ethylene oxide can be used.

[0306] <2 R 3 The main chain parts of R 1 Side R 2 With R 4 Side R 2 Same situation>

[0307] (Second reaction)

[0308] Prepare R in formula (1) 1 Side R 2 (=R 4 Side R 2 ) are respectively provided with hydroxymethyl (-CH2OH) at both ends of the corresponding perfluoropolyether chain. Furthermore, a protecting group (e.g., THP group) is introduced into the hydroxyl group of the hydroxymethyl group provided at one end of the above-mentioned fluorine-based compound to obtain an intermediate compound 2-2.

[0309] (Third reaction)

[0310] Next, the intermediate compound 2-1 and R 3 The epoxy group corresponding to the main chain portion of the intermediate compound 2-2 reacts with the hydroxyl group of the intermediate compound 2-2. 2 The two ends of the corresponding perfluoropolyether chain are respectively connected to R through a methylene group. 3 The linking group corresponding to the main chain portion of R is bonded to R via methylene groups at both ends. 1 Side R 2 (=R 4 Side R 2 ) is an intermediate compound 2-3 of a perfluoropolyether chain corresponding to R 3 In the two linking groups corresponding to the main chain portion of , one secondary hydroxyl group generated by the reaction between the epoxy group of the intermediate compound 2-1 and the hydroxyl group of the intermediate compound 2-2 is respectively arranged.

[0311] <2 R 3 The main chain parts of R 1 Side R 2 With R 4 Side R 2 In different situations>

[0312] (Second reaction)

[0313] In the manufacturing formula (1), R 1 Side R 2 With R4 Side R 2 In the case of compounds having different perfluoropolyether chains, the following reactions are carried out as the second reaction and the third reaction.

[0314] With R 1 Side R 2 With R 4 Side R 2 The second reaction under the same conditions is carried out in the same manner to produce 1 Side R 2 The first intermediate compound 2-2-1 of the corresponding perfluoropolyether chain. 1 Side R 2 With R 4 Side R 2 The second reaction under the same conditions is carried out in the same manner to produce 4 Side R 2 The corresponding second intermediate compound of the perfluoropolyether chain is 2-2-2.

[0315] (Third reaction)

[0316] In making the intermediate compound 2-1 and R 3 The epoxy group corresponding to the main chain portion of the first intermediate compound 2-2-1 reacts with the hydroxyl group of the first intermediate compound 2-2-1, and then purifies the first intermediate compound 2-2-1. 2 One end of the corresponding perfluoropolyether chain is bonded to R via a methylene group. 3 The main chain portion corresponding to the connecting group, methylene and R 1 Side R 2 The corresponding perfluoropolyether chain has an intermediate compound having an epoxy group at the other end. Next, the epoxy group of the obtained intermediate compound is reacted with the hydroxyl group of the second intermediate compound 2-2-2.

[0317] Thus, the R 2 One end of the corresponding perfluoropolyether chain is bonded to R via a methylene group. 3 The main chain portion corresponding to the connecting group, methylene and R 1 Side R 2 The corresponding perfluoropolyether chain has a methylene group bonded to R 3 The main chain portion corresponding to the connecting group, methylene and R 4 Side R 2 The corresponding perfluoropolyether chain, intermediate compound 2-3-1. 1 Side R 2 , and R 4 Side R 2 In different intermediate compounds 2-3-1, in the presence of two R 3In each linking group corresponding to the main chain portion, a secondary hydroxyl group generated by the reaction of the hydroxyl group of the first intermediate compound 2-2-1 or the hydroxyl group of the second intermediate compound 2-2-2 with the epoxy group of the intermediate compound 2-1 is arranged.

[0318] The intermediate compound 2-3-1 can also be prepared by making the intermediate compound 2-1 3 The epoxy group corresponding to the main chain portion of is reacted with the hydroxyl group of the second intermediate compound 2-2-2, followed by purification, and the obtained compound is reacted with the hydroxyl group of the first intermediate compound 2-2-1.

[0319] <2 R 3 When the main chain part is different >

[0320] (Third reaction)

[0321] In the manufacturing formula (1), the two R 3 In the case of a compound having a different main chain portion, the following reaction is performed as the third reaction.

[0322] Instead of using the above two R 3 The intermediate compound 2-1 is prepared by the first reaction when the main chain parts are the same as those of 3 The main chain part of R is different from that of R 2 One end has an R 1 Side R 3 The main chain part corresponds to the epoxy group in R 2 The other end has an R 4 Side R 3 The intermediate compound 2-1-2 has an epoxy group corresponding to the main chain portion, and in addition, two R 3 In the case where the main chain part is the same, the third reaction is carried out in the same manner.

[0323] Specifically, in R 1 Side R 2 With R 4 Side R 2 In the same case, the intermediate compound 2-1-2 is reacted with R 1 Side R 3 The epoxy group corresponding to the main chain part of the intermediate compound 2-2 reacts with the hydroxyl group of the intermediate compound 2-2, and the intermediate compound 2-1-2 and R 4 Side R 3 The epoxy group corresponding to the main chain part reacts with the hydroxyl group of the intermediate compound 2-2.

[0324] In R 1 Side R2 With R 4 Side R 2 Under different circumstances, the intermediate compound 2-1-2 will be 1 Side R 3 The compound obtained by reacting the epoxy group corresponding to the main chain part of the first intermediate compound 2-2-1 with the hydroxyl group of the second intermediate compound 2-2-2 is reacted. Alternatively, the epoxy group corresponding to the main chain part of the intermediate compound 2-1-2 with R 4 Side R 3 The compound obtained by reacting the epoxy group corresponding to the main chain portion of with the hydroxyl group of the second intermediate compound 2-2-2 reacts with the hydroxyl group of the first intermediate compound 2-2-1.

[0325] Thus, the R 2 One end of the corresponding perfluoropolyether chain is bonded to R via a methylene group. 1 Side R 3 The main chain portion corresponding to the connecting group, methylene and R 1 Side R 2 The corresponding perfluoropolyether chain has a methylene group bonded to R 4 Side R 3 The main chain portion corresponding to the connecting group, methylene and R 4 Side R 2 The corresponding perfluoropolyether chain, intermediate compound 2-3-2. 1 Side R 3 With R 4 Side R 3 In different intermediate compounds 2-3-2, in the presence of two R 3 In each linking group corresponding to the main chain portion, the hydroxyl group of the intermediate compound 2-2 (or the first intermediate compound 2-2-1 and the second intermediate compound 2-2-2) and one secondary hydroxyl group generated by reacting with the epoxy group of the intermediate compound 2-1-2 are respectively arranged.

[0326] (Fourth reaction)

[0327] Then, in 2 R 3 The main chain parts are the same and R 1 Side R 2 With R 4 Side R 2 The same intermediate compound 2-3, 2 R 3 The main chain parts are the same and R 1 Side R 2 With R 4 Side R 2 Different intermediate compounds 2-3-1, 2 R 3The main chain part is different and R 1 Side R 2 With R 4 Side R 2 In any of the same or different intermediate compounds 2-3-2, two R 3 The secondary hydroxyl groups in the main chain are chemically modified and converted into primary hydroxyl groups.

[0328] In 2 R 3 When the side chain part of is the same as that of R (intermediate compound 2-3 or intermediate compound 2-3-1), 3 The side chain portion of the structure corresponds to the halogen compound having a protective group introduced into the terminal primary hydroxyl group and becomes two R 3 The secondary hydroxyl group of the main chain portion corresponding to the linker is reacted to produce the intermediate compound 2-4.

[0329] In 2 R 3 When the side chain part of is different (intermediate compound 2-3-2), specifically, it is made to be the same as R 1 Side R 3 The side chain of the structure corresponds to that of the primary hydroxyl group at the terminal, and a halogen compound having a protective group is introduced into the intermediate compound 2-3-2 to form R 1 Side R 3 The compound obtained by reacting the secondary hydroxyl group of the linking group corresponding to the main chain part of 4 Side R 3 The side chain of the structure corresponds to the structure and the primary hydroxyl group at the end is introduced into a halogen compound with a protective group. 4 Side R 3 The side chain of the structure corresponds to the structure of the primary hydroxyl group at the end, and the halogen compound with a protective group is introduced into the intermediate compound 2-3-2 to form R 4 Side R 3 The compound obtained by reacting the secondary hydroxyl group of the linking group corresponding to the main chain part of 1 Side R 3 The structure corresponding to the side chain part of the halogen compound and the primary hydroxyl group at the terminal are introduced into the protective group to react. Thus, the intermediate compound 2-4-1 is produced.

[0330] As used in the second manufacturing method, R 1 Side R 3 and R 4 Side R 3 A halogen compound having a structure corresponding to the side chain portion of the present invention and having a protective group introduced into the terminal primary hydroxyl group can be used in the first production method and can be used as a halogen compound for R 3The same substance is used in which a halogen compound having a protecting group is introduced into the primary hydroxyl group at the terminal and the side chain portion has a structure corresponding to that of the substance.

[0331] (Fifth Reaction)

[0332] Next, the protecting groups (for example, THP groups) bonded to both ends of the intermediate compound 2-4 (or the intermediate compound 2-4-1) are removed by a known method to obtain the intermediate compound 2-5.

[0333] (Sixth Reaction)

[0334] Next, the same operation as the fifth reaction in the first production method is carried out to obtain a compound having the same R as in formula (1). 1 - an epoxy compound corresponding to the group (or, having 1 - the corresponding group of epoxy compounds and having R 4 - corresponding group) and the hydroxyl groups bound to both ends of the intermediate compound 2-5. Thus, a 1 - corresponding group, having at the other end the same 4 - the corresponding intermediate compound 2-6.

[0335] (Seventh Reaction)

[0336] Finally, all the protecting groups introduced into the intermediate compound 2-6 are removed. As a method for removing the protecting groups, the same method as in the first production method can be used.

[0337] By carrying out the above steps, a compound wherein x is 2 in the formula (1) can be produced.

[0338] The fluorine-containing ether compound of this embodiment is a compound represented by formula (1). Therefore, even if the lubricating layer formed on the protective layer using the lubricant containing the fluorine-containing ether compound of this embodiment is thin, it has excellent chemical resistance and good flying stability of the magnetic head.

[0339] [Lubricant for magnetic recording media]

[0340] The lubricant for magnetic recording media according to the present embodiment contains the fluorine-containing ether compound represented by the above formula (1).

[0341] The lubricant of the present embodiment may be a mixture of known materials used as lubricant materials as needed, as long as the properties due to the inclusion of the fluorine-containing ether compound represented by the above formula (1) are not impaired.

[0342] Specific examples of known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), and Moresco A20H (manufactured by Moresco).

[0343] 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.

[0344] 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.

[0345] Since the lubricant of the present embodiment contains the fluorine-containing ether compound represented by the above formula (1), it is possible to form a lubricating layer which has high resistance to chemical substances and good flying stability of the magnetic head even if the thickness is thin.

[0346] [Magnetic recording media]

[0347] 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.

[0348] 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.

[0349] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0350] 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 .

[0351] "Substrate"

[0352] 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.

[0353] 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.

[0354] "Attachment Layer"

[0355] 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.

[0356] 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.

[0357] "Soft magnetic layer"

[0358] The soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer composed of 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 an intermediate layer composed of a Ru film between two soft magnetic films.

[0359] Examples of the material of the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy.

[0360] 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.

[0361] The soft magnetic layer 13 can be formed by, for example, sputtering.

[0362] "1st base layer"

[0363] 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.

[0364] 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.

[0365] The first base layer 14 can be formed by, for example, sputtering.

[0366] "Second base layer"

[0367] The second underlayer 15 is a layer that is 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.

[0368] 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 the layers may be composed of the same material, or at least one layer may be composed of a different material.

[0369] The second base layer 15 can be formed by, for example, sputtering.

[0370] "Magnetic layer"

[0371] The magnetic layer 16 is composed of a magnetic film whose easy magnetization axis is oriented in a vertical or horizontal direction relative 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 also be a layer containing oxide, Cr, B, Cu, Ta, Zr, etc.

[0372] 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 .

[0373] The magnetic layer 16 may be composed of a single layer or a plurality of magnetic layers formed of materials having different compositions.

[0374] 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.

[0375] The first magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides. The second magnetic layer may contain the same material as the first magnetic layer. The second magnetic layer preferably has a granular structure.

[0376] 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.

[0377] 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.

[0378] The non-magnetic layer of the magnetic layer 16 arranged between adjacent magnetic layers 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.

[0379] 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.

[0380] The non-magnetic layer can be formed by, for example, sputtering.

[0381] In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer in which the easy magnetization axis is oriented perpendicularly to the substrate surface. The magnetic layer 16 may be an in-plane magnetic recording magnetic layer.

[0382] 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.

[0383] "Protective layer"

[0384] 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, so it is preferred.

[0385] 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).

[0386] 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. For example, the carbon-based protective layer is 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.

[0387] The thickness of the protective layer 17 is preferably 1 nm to 7 nm. When the thickness of the protective layer 17 is 1 nm or more, sufficient performance as the protective layer 17 is obtained. When the thickness of the protective layer 17 is 7 nm or less, it is preferred from the viewpoint of reducing the thickness of the protective layer 17.

[0388] 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.

[0389] 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.

[0390] "Lubricating layer"

[0391] 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.

[0392] Lubricating layer 18 Figure 1 As shown in FIG. 1 , 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 on the protective layer 17. Therefore, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.

[0393] When the protective layer 17 disposed under the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 is bonded to the protective layer 17 by a particularly 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.

[0394] 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.

[0395] "Method for forming a lubricating layer"

[0396] 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.

[0397] 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.

[0398] 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.).

[0399] 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.

[0400] 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 put into the dipping tank of the dipping coating device. Then, 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.

[0401] 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.

[0402] 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.

[0403] 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.

[0404] 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.

[0405] The magnetic recording medium 10 of the present embodiment has at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 arranged 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, a magnetic recording medium 10 having excellent chemical resistance and good floating stability of the magnetic head is obtained. Therefore, the reliability of the magnetic recording medium 10 of the present embodiment, especially the suppression of silicon contamination and durability are excellent. Therefore, 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 can operate stably for a long time even in a harsh environment with a variety of uses. 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.

[0406] Example

[0407] The present invention will be described in more detail below by way of examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

[0408] [Example 1]

[0409] The compound represented by the above formula (1A) was obtained by the method shown below.

[0410] (First reaction)

[0411] In a 300 mL eggplant flask under nitrogen atmosphere, add HOCH2CF2CF2O (CF2CF2CF2O) l20 g of a compound represented by CF2CF2CH2OH (where l in the formula represents the average degree of polymerization and is 3.8) (number average molecular weight 909, molecular weight distribution 1.1), 1.95 g of 3,4-dihydro-2H-pyran, and 44 mL of a mixed solution (volume ratio 1:1) of Asahiklin (registered trademark) AE3000 (manufactured by AGC Co., Ltd.) and dichloromethane as a fluorine-based solvent were stirred at 0°C until it became uniform to prepare a mixture. 0.084 g of p-toluenesulfonic acid monohydrate was added to the mixture, and after stirring at 0°C for 30 minutes, it was stirred at room temperature for 2 hours to react.

[0412] The reaction product obtained after the reaction was cooled to 0°C, 50 mL of saturated sodium bicarbonate water was added to stop the reaction. The resulting reaction solution was transferred to a separatory funnel and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with saline 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 10.8 g of the compound represented by the following formula (7) as an intermediate compound 1-1.

[0413]

[0414] (In formula (7), l, which indicates the average degree of polymerization, represents 3.8, and THP represents tetrahydropyranyl.)

[0415] (Second reaction)

[0416] In a 200 mL eggplant flask under a nitrogen atmosphere, 10.8 g (molecular weight 993, 10.9 mmol) of the compound represented by formula (7) as the intermediate compound 1-1, 10.2 mL of tert-butyl alcohol, and 0.37 g (molecular weight 112, 3.3 mmol) of potassium tert-butylate were added, and stirred at room temperature until it became uniform. 0.49 mL (molecular weight 137, 6.0 mmol) of epibromohydrin was added to the uniform liquid, and stirred at 70°C for 2 hours to react. Next, 0.25 g of potassium tert-butylate was added, and stirred at 70°C for 2 hours to react. Then, 0.25 g of potassium tert-butylate was added, and stirred at 70°C for 13 hours to react.

[0417] 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 brine, and extracted 3 times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine in this order, 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. By performing the above steps, 7.6 g of the compound represented by the following formula (8) was obtained as the intermediate compound 1-2.

[0418]

[0419] (In formula (8), THP represents a tetrahydropyranyl group, and Rf2 is represented by the above formula; l in Rf2, which represents an average degree of polymerization, represents 3.8.)

[0420] (Third reaction)

[0421] In a 200 mL eggplant flask under a nitrogen atmosphere, 7.6 g of the compound represented by formula (8) as the intermediate compound 1-2 (molecular weight 2042, 3.7 mmol), 7.4 mL of N,N-dimethylformamide, and 0.16 g of sodium hydride (purity 60%, molecular weight 24.00, 4.1 mmol) were added, and stirred at 0°C until it became uniform. After further stirring at room temperature for 30 minutes, 1.2 mL of benzyl 2-bromoethyl ether (BnO(CH2)2Br (Bn represents benzyl)) (molecular weight 215, 7.4 mmol) was added dropwise at 0°C, and stirred at room temperature until it became uniform. 0.16 g of sodium hydride was added to the uniform liquid, and after stirring at room temperature for 20 hours, the mixture was stirred at 40°C for 3 hours to react.

[0422] The reaction solution obtained after the reaction was returned to room temperature, the reaction solution was transferred to a separatory funnel added with 40mL of saline solution a little bit, and extracted 3 times with 40mL of ethyl acetate. The organic layer was washed with 20mL of saline solution and dehydrated by anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated, and the residue was refined by silica gel column chromatography.

[0423] By carrying out the above steps, 5.4 g of a compound represented by the following formula (9) was obtained as an intermediate compound 1-3.

[0424]

[0425] (In formula (9), THP represents tetrahydropyranyl, Bn represents benzyl, Rf2 is the same as Rf2 in formula (8); l in Rf2, which represents the average degree of polymerization, represents 3.8.)

[0426] (Fourth reaction)

[0427] In a 200 mL eggplant flask under a nitrogen atmosphere, 6.8 g of the compound represented by formula (9) as the intermediate compound 1-3 (molecular weight 2176, 3.1 mmol) and 46 mL of trifluoroethanol were added, and stirred at room temperature until the mixture became uniform to prepare a mixture. 0.12 g of p-toluenesulfonic acid monohydrate was added to the mixture, and the mixture was stirred at room temperature for 1 hour to react.

[0428] To the reaction product obtained after the reaction, 0.13 mL of diisopropylethylamine was added to stop the reaction. The obtained reaction liquid residue was purified by silica gel column chromatography to obtain 4.5 g of a compound represented by the following formula (10) as an intermediate compound 1-4.

[0429]

[0430] (In formula (10), Bn represents a benzyl group, and Rf2 is the same as Rf2 in formula (8); l in Rf2, which represents an average degree of polymerization, represents 3.8.)

[0431] (Fifth Reaction)

[0432] In a 200 mL eggplant flask under a nitrogen atmosphere, 4.5 g of the compound represented by formula (10) as the intermediate compound 1-4 (number average molecular weight 2008, 2.2 mmol), 1.5 g of the compound represented by the following formula (11) (molecular weight 202.3, 7.2 mmol), and 21 mL of tert-butyl alcohol were added, and stirred at room temperature until it became uniform. 0.025 g of potassium tert-butylate was further added to the uniform liquid, and the mixture was stirred at 70° C. for 16 hours to react.

[0433] The compound represented by the formula (11) is synthesized by oxidizing a compound in which the hydroxyl group of ethylene glycol monoallyl ether is protected using dihydropyran.

[0434]

[0435] (In formula (11), THP represents tetrahydropyranyl.)

[0436] 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 3.3 g of the compound represented by the following formula (12) as an intermediate compound 1-5.

[0437]

[0438] (In formula (12), THP represents tetrahydropyranyl, Bn represents benzyl, and Rf2 is the same as Rf2 in formula (8); l in Rf2, which represents the average degree of polymerization, represents 3.8.)

[0439] (Sixth Reaction)

[0440] In a 200 mL eggplant flask under a nitrogen atmosphere, 3.3 g of the compound represented by formula (12) as the intermediate compound 1-5 (number average molecular weight 2413, 1.4 mmol), 33 mL of methanol, and 3.3 mL of formic acid were added and stirred at room temperature until it became uniform. 0.33 g of palladium carbon (Pd / C) was further added to the uniform liquid, and the mixture was stirred at 70°C for 2 hours to react.

[0441] The reaction solution obtained after the reaction was filtered to remove Pd / C, and the filtrate was concentrated. After concentration, the residue was purified by silica gel column chromatography to obtain 2.4 g (number average molecular weight 2154, 1.1 mmol) of the compound represented by the above formula (1A) (Rf21a in formula (1A) is represented by formula (1AF). l1a representing the average degree of polymerization in the two Rf21a is 3.8.).

[0442] The obtained compound (1A) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0443] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.34(40H)

[0444] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0445] [Example 2]

[0446] In the fifth reaction, 1.6 g (molecular weight 216, 7.2 mmol) of the compound represented by the following formula (13) was used instead of the compound represented by formula (11). The same operation as in Example 1 was carried out to obtain 2.4 g (number average molecular weight 2182, 1.1 mmol) of the compound represented by the above formula (1B) (Rf21b in formula (1B) is represented by formula (1BF). l1b representing the average degree of polymerization among the two Rf21bs is 3.8).

[0447] The compound represented by formula (13) is synthesized by protecting one hydroxyl group of 1,3-propanediol with a tetrahydropyranyl (THP) group and reacting the other hydroxyl group with epibromohydrin.

[0448]

[0449] (In formula (13), THP represents tetrahydropyranyl.)

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

[0451] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(40H)

[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 3]

[0454] In the fifth reaction, the operations up to the sixth reaction were carried out in the same manner as in Example 1 except that 2.3 g (molecular weight 320, 7.2 mmol) of the compound represented by the following formula (14) was used instead of the compound represented by formula (11).

[0455] To the reaction product obtained in the sixth reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in that order, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was purified by silica gel column chromatography. By performing the above steps, 2.5 g (number average molecular weight 2302, 1.1 mmol) of the compound represented by the above formula (1C) (Rf21c in formula (1C) is represented by formula (1CF). l1c representing the average degree of polymerization among the two Rf21c's is 3.8.) was obtained.

[0456] The compound represented by formula (14) was synthesized by the following method.

[0457] A tert-butyldimethylsilyl (TBS) group was introduced as a protecting group to the primary hydroxyl group of 3-allyloxy-1,2-propanediol, and a methoxymethyl (MOM) group was introduced as a protecting group to the secondary hydroxyl group of the obtained compound. The TBS group was removed from the obtained compound, and 2-bromoethoxytetrahydropyran was reacted with the generated primary hydroxyl group. The double bond of the obtained compound was oxidized.

[0458] Through the above steps, the compound represented by formula (14) is obtained.

[0459]

[0460] (In formula (14), THP represents tetrahydropyranyl and MOM represents methoxymethyl.)

[0461] The obtained compound (1C) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0462] 1 H-NMR (CD3COCD3): δ [ppm] = 3.37~4.36 (52H)

[0463] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0464] [Example 4]

[0465] In the fifth reaction, the operations up to the sixth reaction were carried out in the same manner as in Example 1 except that 2.4 g (molecular weight 334, 7.2 mmol) of the compound represented by the following formula (15) was used instead of the compound represented by formula (11).

[0466] To the reaction product obtained in the sixth reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in that order, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was purified by silica gel column chromatography. By performing the above steps, 2.6 g (number average molecular weight 2331, 1.1 mmol) of the compound represented by the above formula (1D) (Rf21d in formula (1D) is represented by formula (1DF). l1d representing the average degree of polymerization among the two Rf21d is 3.8.) was obtained.

[0467] The compound represented by formula (15) was synthesized by the following method.

[0468] A tert-butyldimethylsilyl (TBS) group was introduced as a protecting group into the primary hydroxyl group of 3-allyloxy-1,2-propanediol, and a methoxymethyl (MOM) group was introduced as a protecting group into the secondary hydroxyl group of the obtained compound. The TBS group was removed from the obtained compound, and 2-(chloropropoxy)tetrahydro-2H-pyran was reacted with the generated primary hydroxyl group. The double bond of the obtained compound was oxidized. Through the above steps, a compound represented by formula (15) was obtained.

[0469]

[0470] (In formula (15), THP represents tetrahydropyranyl and MOM represents methoxymethyl.)

[0471] The obtained compound (1D) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0472] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.34(52H)

[0473] 19F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0474] [Example 5]

[0475] In the fifth reaction, 1.6 g (molecular weight 216, 7.2 mmol) of the compound represented by the following formula (16) was used instead of the compound represented by formula (11). The same operation as in Example 1 was carried out to obtain 2.4 g (number average molecular weight 2182, 1.1 mmol) of the compound represented by the above formula (1E) (Rf21e in formula (1E) is represented by formula (1EF). The average degree of polymerization l1e among the two Rf21es is 3.8.).

[0476] The compound represented by formula (16) is synthesized by oxidizing the double bond of a compound obtained by reacting 3-butene-1-ol with 2-bromoethoxytetrahydropyran.

[0477]

[0478] (In formula (16), THP represents tetrahydropyranyl.)

[0479] The obtained compound (1E) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0480] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.79(4H), 3.41~4.33(40H)

[0481] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0482] [Example 6]

[0483] In the fifth reaction, the operations up to the sixth reaction were carried out in the same manner as in Example 1 except that 2.4 g (molecular weight 334, 7.2 mmol) of the compound represented by the following formula (17) was used instead of the compound represented by formula (11).

[0484] To the reaction product obtained in the sixth reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in this order, and dehydrated with anhydrous sodium sulfate. After the desiccant was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography. By performing the above steps, 2.6 g (number average molecular weight 2331, 1.1 mmol) of the compound represented by the above formula (1F) (Rf21f in formula (1F) is represented by formula (1FF). l1f representing the average degree of polymerization among the two Rf21f is 3.8.) was obtained.

[0485] The compound represented by formula (17) was synthesized by the following method.

[0486] The hydroxyl group of ethylene glycol monoallyl ether was protected with dihydropyran, and the double bond of the obtained compound was oxidized. The epoxy group of the compound obtained by oxidizing the double bond was reacted with the hydroxyl group of 3-butene-1-ol. The secondary hydroxyl group of the obtained compound was protected with a methoxymethyl (MOM) group, and the double bond of the obtained compound was oxidized. Through the above steps, the compound represented by formula (17) was obtained.

[0487]

[0488] (In formula (17), THP represents tetrahydropyranyl and MOM represents methoxymethyl.)

[0489] The obtained compound (1F) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0490] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.79(4H), 3.41~4.33(52H)

[0491] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0492] [Example 7]

[0493] In the first reaction, instead of HOCH2CF2CF2O (CF2CF2CF2O) l The compound shown in CF2CF2CH2OH is used instead of HOCH2CF2O (CF2CF2O). j (CF2O) k 20 g of the compound represented by CF2CH2OH (wherein j represents the average degree of polymerization and k represents the average degree of polymerization, which is 4.0) (number average molecular weight 906, molecular weight distribution 1.1) was prepared, and in the fifth reaction, 1.2 g (molecular weight 172, 7.2 mmol) of the compound represented by the following formula (18) was used instead of the compound represented by formula (11). Otherwise, the same operation as in Example 1 was carried out to obtain 2.3 g (number average molecular weight 2089, 1.1 mmol) of the compound represented by the above formula (1G) (Rf11g in formula (1G) is represented by formula (1GF). Among the two Rf11g, j1g representing the average degree of polymerization is 4.0, and k1g representing the average degree of polymerization is 4.0).

[0494] The compound represented by formula (18) is synthesized by introducing a tetrahydropyranyl (THP) group into the primary hydroxyl group of 3-buten-1-ol and oxidizing the double bond of the resulting compound.

[0495]

[0496] (In formula (18), THP represents tetrahydropyranyl.)

[0497] The obtained compound (1G) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0498] 1 H-NMR (CD3COCD3): δ[ppm]=1.66~1.79(4H), 3.42~4.34(32H)

[0499] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(16F), -77.7(4F), -80.3(4F), -91.0~-88.5(32F)

[0500] [Example 8]

[0501] Instead of the compound represented by formula (18), 1.4 g (molecular weight 200, 7.2 mmol) of the compound represented by the following formula (19) was used. The same operations as in Example 7 were carried out, and 2.4 g (number average molecular weight 2145, 1.1 mmol) of the compound represented by the above formula (1H) (Rf11h in formula (1H) is represented by formula (1HF). j1h representing the average degree of polymerization of the two Rf11h is 4.0, and k1h representing the average degree of polymerization is 4.0) was obtained.

[0502] The compound represented by formula (19) is synthesized by introducing a tetrahydropyranyl (THP) group into the primary hydroxyl group of 5-hexen-1-ol and oxidizing the double bond of the resulting compound.

[0503]

[0504] (In formula (19), THP represents tetrahydropyranyl.)

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

[0506] 1 H-NMR (CD3COCD3): δ[ppm]=1.37~1.81(12H), 3.39~4.33(32H)

[0507] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(16F), -77.7(4F), -80.3(4F), -91.0~-88.5(32F)

[0508] [Example 9]

[0509] In the first reaction, instead of HOCH2CF2CF2O (CF2CF2CF2O) l The compound shown in CF2CF2CH2OH is used instead of HOCH2CF2O (CF2CF2O). j (CF2O) k 20 g of the compound represented by CF2CH2OH (wherein j representing the average degree of polymerization is 6.3, and k representing the average degree of polymerization is 0) (number average molecular weight 909, molecular weight distribution 1.1) was used, and in the fifth reaction, 2.2 g of the compound represented by the following formula (20) (molecular weight 304, 7.2 mmol) was used instead of the compound represented by formula (11). Except for this, the operations up to the sixth reaction were carried out in the same manner as in Example 1.

[0510] To the reaction product obtained in the sixth reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in that order, and dehydrated with anhydrous sodium sulfate. After the desiccant was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography. By performing the above steps, 2.5 g (number average molecular weight 2270, 1.1 mmol) of the compound represented by the above formula (1I) (Rf11i in formula (1I) is represented by formula (1IF). j1i representing the average degree of polymerization among the two Rf11i is 6.3, and k1i representing the average degree of polymerization is 0.) was obtained.

[0511] The compound represented by formula (20) was synthesized by the following method.

[0512] A tetrahydropyranyl (THP) group is introduced into the primary hydroxyl group of 4-penten-1-ol, and the double bond of the obtained compound is oxidized. The compound obtained by oxidizing the double bond is reacted with allyl alcohol. The secondary hydroxyl group of the obtained compound is protected with a methoxymethyl (MOM) group, and the double bond of the obtained compound is oxidized. The compound represented by formula (20) is obtained through the above steps.

[0513]

[0514] (In formula (20), THP represents tetrahydropyranyl and MOM represents methoxymethyl.)

[0515] The obtained compound (1I) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0516] 1 H-NMR (CD3COCD3): δ[ppm]=1.34~1.67(8H), 3.39~4.34(44H)

[0517] 19 F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0518] [Example 10]

[0519] In the fifth reaction, 2.0 g (molecular weight 272, 7.2 mmol) of the compound represented by the following formula (21) was used instead of the compound represented by formula (11). The same operation as in Example 1 was carried out to obtain 2.5 g (number average molecular weight 2295, 1.1 mmol) of the compound represented by the above formula (1J) (Rf21j in formula (1J) is represented by formula (1JF). The average degree of polymerization of the two Rf21j is represented by l1j, which is 3.8.).

[0520] The compound represented by formula (21) was synthesized by the following method.

[0521] 1,3-Diallyloxy-2-propanol was reacted with 3,4-dihydro-2H-pyran, and one double bond of the obtained compound was oxidized using m-chloroperbenzoic acid. Through the above steps, a compound represented by formula (21) was obtained.

[0522]

[0523] (In formula (21), THP represents tetrahydropyranyl.)

[0524] The obtained compound (1J) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0525] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.34(46H), 5.14~5.22(2H), 5.26~5.35(2H), 5.87~5.91(2H) 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0526] [Example 11]

[0527] In the fifth reaction, 2.2 g (molecular weight 300, 7.2 mmol) of the compound represented by the following formula (22) was used instead of the compound represented by formula (11). The same operation as in Example 1 was carried out to obtain 2.6 g (number average molecular weight 2351, 1.1 mmol) of the compound represented by the above formula (1K) (Rf21k in formula (1K) is represented by formula (1KF). l1k representing the average degree of polymerization among the two Rf21ks is 3.8).

[0528] The compound represented by the following formula (22) was synthesized by the method shown below.

[0529] Two equivalents of 3-butene-1-ol and one equivalent of epichlorohydrin were reacted. The obtained compound was reacted with 3,4-dihydro-2H-pyran, and the secondary hydroxyl group of the compound was protected with a tetrahydropyranyl (THP) group. The double bond on one side of the obtained compound was oxidized using m-chloroperbenzoic acid. The compound represented by formula (22) was obtained through the above steps.

[0530]

[0531] (In formula (22), THP represents tetrahydropyranyl.)

[0532] The obtained compound (1K) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0533] 1 H-NMR (CD3COCD3): δ[ppm]=1.66~1.81(4H), 2.33~2.43(4H), 3.39~4.34(46H), 5.14~5.22(2H), 5.26~5.35(2H), 5.87~5.91(2H)

[0534] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0535] [Example 12]

[0536] In the fifth reaction, 2.1 g (molecular weight 299, 7.2 mmol) of the compound represented by the following formula (23) was used instead of the compound represented by the formula (20). The same operations as in Example 9 were carried out to obtain 2.6 g (number average molecular weight 2348, 1.1 mmol) of the compound represented by the above formula (1L) (Rf111 in formula (1L) is represented by formula (1LF). j1l representing the average degree of polymerization among the two Rf11l is 6.3, and k1l representing the average degree of polymerization is 0.).

[0537] The compound represented by formula (23) was synthesized by the following method.

[0538] The reaction product obtained by reacting cyanopropanol with epibromohydrin is hydrolyzed. After the primary hydroxyl group of the obtained compound is protected with tert-butyldimethylsilyl, the secondary hydroxyl group is protected with tetrahydropyranyl. The tert-butyldimethylsilyl group is deprotected from the compound having the secondary hydroxyl group protected, and the compound is reacted with epibromohydrin. The compound represented by formula (23) is obtained by the above steps.

[0539]

[0540] (In formula (23), THP represents tetrahydropyranyl.)

[0541] The obtained compound (1L) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0542] 1 H-NMR (CD3COCD3): δ[ppm]=1.15~1.25(4H), 2.00~2.10(4H), 3.39~4.34(46H)

[0543] 19 F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0544] [Example 13]

[0545] In the fifth reaction, 2.8 g (molecular weight 389, 7.2 mmol) of the compound represented by the following formula (24) was used instead of the compound represented by formula (18). The same operations as in Example 7 were carried out to obtain 2.6 g (number average molecular weight 2353, 1.1 mmol) of the compound represented by the above formula (1M) (Rf11m in formula (1M) is represented by formula (1MF). Among the two Rf11ms, j1m representing the average degree of polymerization is 4.0, and k1m representing the average degree of polymerization is 4.0.).

[0546] The compound represented by formula (24) was synthesized by the following method.

[0547] The hydroxyl group of ethylene glycol monoallyl ether was protected with dihydropyran, and the double bond of the obtained compound was oxidized. The epoxy group of the compound obtained by oxidizing the double bond was reacted with the hydroxyl group of 4-penten-1-ol. The secondary hydroxyl group of the obtained compound was protected with a THP group, and the double bond of the obtained compound was oxidized. The compound represented by formula (24) was obtained through the above steps.

[0548]

[0549] (In formula (24), THP represents tetrahydropyranyl.)

[0550] The obtained compound (1M) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0551] 1 H-NMR (CD3COCD3): δ[ppm]=1.64~1.81(8H), 3.39~4.34(52H)

[0552] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(16F), -77.7(4F), -80.3(4F), -91.0~-88.5(32F)

[0553] [Example 14]

[0554] In the fifth reaction, the operations up to the sixth reaction were carried out in the same manner as in Example 1 except that 1.9 g (molecular weight 264, 7.2 mmol) of the compound represented by the following formula (25) was used instead of the compound represented by formula (11).

[0555] To the reaction product obtained in the sixth reaction, 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 resulting reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed in the order of 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was refined by silica gel column chromatography. By performing the above steps, 2.5 g (number average molecular weight 2270, 1.1 mmol) of the compound represented by the above formula (1N) (Rf21n in formula (1N) is represented by formula (1NF). l1n representing the average degree of polymerization among the two Rf21ns is 3.8.) was obtained.

[0556] The compound represented by formula (25) was synthesized by the following method.

[0557] 1,2,4-butanetriol was reacted with benzaldehyde dimethyl acetal. Thus, a compound in which the hydroxyl groups bonded to the carbon at the 2-position and the carbon at the 4-position of 1,2,4-butanetriol were protected was synthesized. This compound was reacted with 2-bromoethyloxirane. Through the above steps, a compound represented by formula (25) was obtained.

[0558]

[0559] (In formula (25), Ph represents a phenyl group.)

[0560] The obtained compound (1N) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0561] 1 H-NMR (CD3COCD3): δ[ppm]=1.66~1.85(8H), 3.31~4.43(44H)

[0562] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0563] [Example 15]

[0564] In the fifth reaction, 2.3 g (molecular weight 317, 7.2 mmol) of the compound represented by the following formula (26) was used instead of the compound represented by the formula (20). The same operation as in Example 9 was carried out to obtain 2.6 g (number average molecular weight 2384, 1.1 mmol) of the compound represented by the above formula (1O) (Rf11o in formula (1O) is represented by formula (1OF). j1o representing the average degree of polymerization among the two Rf11o is 6.3, and k1o representing the average degree of polymerization is 0.).

[0565] The compound represented by formula (26) was synthesized by the following method.

[0566] The compound is obtained by reacting 2-acetamideethanol with allyl glycidyl ether. Then, the secondary hydroxyl group of the obtained compound is protected with a THP group. The terminal double bond of the obtained compound is oxidized in dichloromethane using m-chloroperbenzoic acid. Through the above steps, the compound represented by formula (26) is obtained.

[0567]

[0568] (In formula (26), THP represents tetrahydropyranyl.)

[0569] The obtained compound (1O) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0570] 1 H-NMR (CD3COCD3): δ[ppm]=1.80~1.90(6H), 3.32~4.39(50H), 7.25~7.41(2H)

[0571] 19 F-NMR (CD3COCD3): δ [ppm] = -78.6 (4F), -81.3 (4F), -90.0~-88.5 (50.4F)

[0572] [Example 16]

[0573] The compound represented by the above formula (2A) was obtained by the method shown below.

[0574] (First reaction)

[0575] Under nitrogen atmosphere, in a 200 mL eggplant flask, add HOCH2CF2CF2O (CF2CF2CF2O) l 7.1 g (11.6 mmol) of a compound represented by CF2CF2CH2OH (where l in the formula represents the average degree of polymerization, and is 2.0) (number average molecular weight 610, molecular weight distribution 1.1), 1.5 g (38 mmol) of 60% sodium hydride, and 12 mL of N,N-dimethylformamide were stirred at room temperature until the mixture became uniform. 2.0 mL (24 mmol) of epibromohydrin was further added to the uniform liquid, and the mixture was stirred at 40°C for 2 hours to react.

[0576] The reaction product obtained after the reaction was cooled to 25°C, 80 mL of water was added to stop the reaction. The mixed solution was 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 the desiccant was filtered and separated, the filtrate was concentrated and the residue was refined by silica gel column chromatography to obtain 5.0 g (molecular weight 722, 7.0 mmol) of the compound shown in the following formula (27) as an intermediate compound 2-1.

[0577]

[0578] (In formula (27), l, which represents the average degree of polymerization, represents 2.0.)

[0579] (Second reaction)

[0580] Under nitrogen atmosphere, in a 300 mL eggplant flask, add HOCH2CF2CF2O (CF2CF2CF2O) l 15.5 g of a compound represented by CF2CF2CH2OH (where l in the formula represents the average degree of polymerization and is 2.0) (number average molecular weight 610, molecular weight distribution 1.1), 2.2 g of 3,4-dihydro-2H-pyran, and 88 mL of a mixed solution (volume ratio 1:1) of Asahiklin (registered trademark) AE3000 (manufactured by AGC Co., Ltd.) and dichloromethane as a fluorine-based solvent were stirred at 0°C until it became uniform to prepare a mixture. 0.1 g of p-toluenesulfonic acid monohydrate was added to the mixture, and after stirring at 0°C for 30 minutes, it was stirred at room temperature for 2 hours to react.

[0581] The reaction product obtained after the reaction was cooled to 0°C, and 50 mL of saturated sodium bicarbonate water was added to stop the reaction. The obtained reaction solution was transferred to a separatory funnel and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with brine 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 10.2 g (molecular weight 694, 14.7 mmol) of the compound represented by the above formula (7) as the intermediate compound 2-2 (in formula (7), l representing the average degree of polymerization represents 2.0, and THP represents tetrahydropyranyl).

[0582] (Third reaction)

[0583] In a 200 mL eggplant flask under a nitrogen atmosphere, 10.0 g (molecular weight 694, 14.7 mmol) of the compound represented by formula (7) as the intermediate compound 2-2, 0.23 g of potassium tert-butoxide, and 6.5 mL of tert-butanol were added and stirred at room temperature until it became uniform. 5.0 g (molecular weight 722, 7.0 mmol) of the compound represented by formula (27) as the intermediate compound 2-1 was further added to the uniform liquid, and the mixture was stirred at 70° C. for 16 hours to react.

[0584] 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 11.7 g (molecular weight 2110, 5.5 mmol) of the compound represented by the following formula (28) as an intermediate compound 2-3.

[0585]

[0586] (In formula (28), THP represents a tetrahydropyranyl group, and Rf2 is represented by the above formula; l in Rf2, which represents an average degree of polymerization, represents 2.0.)

[0587] (Fourth reaction)

[0588] In a 200 mL eggplant flask under a nitrogen atmosphere, 11.7 g of the compound represented by formula (28) as the intermediate compound 2-3 (molecular weight 2110, 5.5 mmol), 11 mL of N,N-dimethylformamide, and 2.2 g of sodium hydride (purity 60%, molecular weight 24.00, 55 mmol) were added, and stirred at 0°C until it became uniform, and further stirred at room temperature for 30 minutes. Then, 2.6 mL of benzyl 2-bromoethyl ether (molecular weight 215, 16.6 mmol) was added dropwise at 0°C, and stirred at room temperature until it became uniform. 0.2 g of sodium hydride was added to the uniform liquid, and after stirring at room temperature for 20 hours, it was stirred at 40°C for 3 hours to react.

[0589] The reaction solution obtained after the reaction was returned to room temperature, the reaction solution was transferred to a separatory funnel added with 40mL of saline solution a little bit, and extracted 3 times with 40mL of ethyl acetate. The organic layer was washed with 20mL of saline solution and dehydrated by anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated, and the residue was refined by silica gel column chromatography.

[0590] By carrying out the above steps, 8.6 g of a compound represented by the following formula (29) was obtained as an intermediate compound 2-4.

[0591]

[0592] (In formula (29), THP represents tetrahydropyranyl, Bn represents benzyl, and Rf2 is the same as Rf2 in formula (28); l in Rf2, which represents the average degree of polymerization, represents 2.0.)

[0593] (Fifth Reaction)

[0594] In a 200 mL eggplant flask under a nitrogen atmosphere, 8.6 g of the compound represented by formula (29) as the intermediate compound 2-4 (molecular weight 2379, 3.6 mmol) and 53 mL of trifluoroethanol were added, and stirred at room temperature until the mixture became uniform to prepare a mixture. 0.14 g of p-toluenesulfonic acid monohydrate was added to the mixture, and the mixture was stirred at room temperature for 1 hour to react.

[0595] To the reaction product obtained after the reaction, 0.15 mL of diisopropylethylamine was added to stop the reaction. The obtained reaction liquid residue was purified by silica gel column chromatography to obtain 4.8 g of a compound represented by the following formula (30) as an intermediate compound 2-5.

[0596]

[0597] (In formula (30), Bn represents a benzyl group, and Rf2 is the same as Rf2 in formula (28); l in Rf2, which represents an average degree of polymerization, represents 2.0.)

[0598] (Sixth Reaction)

[0599] Under a nitrogen atmosphere, in a 200-mL eggplant-shaped flask, 4.8 g of the compound represented by formula (30) (number average molecular weight 2211, 2.2 mmol) as the intermediate compound 2-5, 0.92 g of the compound represented by the above formula (11) (molecular weight 202.3, 4.5 mmol), and 2 mL of tert-butanol were added and stirred at room temperature until it became uniform to allow the reaction to proceed.

[0600] 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 3.7 g of the compound represented by the following formula (31) as the intermediate compound 2-6.

[0601]

[0602] (In formula (31), THP represents tetrahydropyranyl, Bn represents benzyl, and Rf2 is the same as Rf2 in formula (28); l in Rf2, which represents the average degree of polymerization, represents 2.0.)

[0603] (Seventh Reaction)

[0604] In a 200 mL eggplant flask under a nitrogen atmosphere, 3.7 g of the compound represented by formula (31) (number average molecular weight 2615, 1.4 mmol), 37 mL of methanol, and 3.7 mL of formic acid as the intermediate compound 2-6 were added, and stirred at room temperature until it became uniform. 0.37 g of palladium carbon (Pd / C) was further added to the uniform liquid, and the mixture was stirred at 70°C for 2 hours to react.

[0605] The reaction liquid obtained after the reaction was filtered to remove Pd / C. After the filtrate was concentrated, the residue was purified by silica gel column chromatography to obtain 2.6 g (number average molecular weight 2267, 1.1 mmol) of the compound represented by the above formula (2A) (Rf22a in formula (2A) is represented by formula (2AF). l2a representing the average degree of polymerization among the three Rf22a is 2.0.

[0606] The obtained compound (2A) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0607] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.34(54H)

[0608] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0609] [Example 17]

[0610] In the sixth reaction, 1.0 g of the compound represented by the above formula (13) was used instead of the compound represented by the formula (11). The same operations as in Example 16 were carried out to obtain 2.5 g (number average molecular weight 2295, 1.1 mmol) of the compound represented by the above formula (2B) (Rf22b in formula (2B) is represented by formula (2BF). l2b representing the average degree of polymerization among the three Rf22bs is 2.0.).

[0611] The obtained compound (2B) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0612] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.35(54H)

[0613] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0614] [Example 18]

[0615] The operations up to the seventh reaction were carried out in the same manner as in Example 16, except that 1.45 g of the compound represented by the above formula (14) was used instead of the compound represented by the formula (11) in the sixth reaction.

[0616] To the reaction product obtained in the seventh reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in that order, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was refined by silica gel column chromatography. By performing the above steps, 2.7 g (number average molecular weight 2415, 1.1 mmol) of the compound represented by the above formula (2C) (Rf22c in formula (2C) is represented by formula (2CF). l2c representing the average degree of polymerization among the three Rf22c is 2.0.) was obtained.

[0617] The obtained compound (2C) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0618] 1 H-NMR (CD3COCD3): δ[ppm]=3.37~4.36(66H)

[0619] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0620] [Example 19]

[0621] The operations up to the seventh reaction were carried out in the same manner as in Example 16, except that 1.52 g of the compound represented by the above formula (15) was used instead of the compound represented by the formula (11) in the sixth reaction.

[0622] To the reaction product obtained in the seventh reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed in the order of 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was refined by silica gel column chromatography. By performing the above steps, 2.7 g (number average molecular weight 2443, 1.1 mmol) of the compound represented by the above formula (2D) (Rf22d in formula (2D) is represented by formula (2DF). l2d representing the average degree of polymerization among the three Rf22d is 2.0.) was obtained.

[0623] The obtained compound (2D) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0624] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.34(66H)

[0625] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0626] [Example 20]

[0627] In the sixth reaction, 1.0 g of the compound represented by the above formula (16) was used instead of the compound represented by formula (11). The same operations as in Example 16 were carried out to obtain 2.5 g (number average molecular weight 2295, 1.1 mmol) of the compound represented by formula (2E) (Rf22e in formula (2E) is represented by formula (2EF). l2e representing the average degree of polymerization among the three Rf22e's) was 2.0.

[0628] The obtained compound (2E) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0629] 1H-NMR (CD3COCD3): δ[ppm]=1.65~1.79(4H), 3.41~4.33(54H)

[0630] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0631] [Example 21]

[0632] The operations up to the seventh reaction were carried out in the same manner as in Example 16, except that 1.5 g of the compound represented by the above formula (17) was used instead of the compound represented by the formula (11) in the sixth reaction.

[0633] To the reaction product obtained in the seventh reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in that order, and dehydrated with anhydrous sodium sulfate. After the desiccant was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography. By performing the above steps, 2.7 g (number average molecular weight 2443, 1.1 mmol) of the compound represented by the above formula (2F) (Rf22f in formula (2F) is represented by formula (2FF). l2f representing the average degree of polymerization among the three Rf22f is 2.0.) was obtained.

[0634] The obtained compound (2F) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0635] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.79(4H), 3.41~4.33(66H)

[0636] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0637] [Example 22]

[0638] In the first and second reactions, HOCH2CF2CF2O (CF2CF2CF2O) is substituted l The compound shown in CF2CF2CH2OH is used instead of HOCH2CF2O (CF2CF2O). j (CF2O) k A compound represented by CF2CH2OH (wherein j represents the average degree of polymerization and k represents the average degree of polymerization) (number average molecular weight 699, molecular weight distribution 1.1), and in the sixth reaction, 0.78 g of the compound represented by the above formula (18) was used instead of the compound represented by formula (11). Except for this, the same operation as in Example 16 was carried out to obtain 2.4 g (number average molecular weight 2221, 1.1 mmol) of the compound represented by the above formula (2G) (Rf12g in formula (2G) is represented by formula (2GF). Among the three Rf12g, j2g representing the average degree of polymerization is 2.4, and k2g representing the average degree of polymerization is 2.4.).

[0639] The obtained compound (2G) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0640] 1 H-NMR (CD3COCD3): δ[ppm]=1.66~1.79(4H), 3.42~4.34(46H)

[0641] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0642] [Example 23]

[0643] In the sixth reaction, 0.91 g of the compound represented by the above formula (19) was used instead of the compound represented by the formula (18). The same operations as in Example 22 were carried out to obtain 2.5 g (number average molecular weight 2277, 1.1 mmol) of the compound represented by the above formula (2H) (Rf12h in formula (2H) is represented by formula (2HF). Among the three Rf12h, j2h representing the average degree of polymerization is 2.4, and k2h representing the average degree of polymerization is 2.4.).

[0644] The obtained compound (2H) is 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0645] 1 H-NMR (CD3COCD3): δ[ppm]=1.37~1.81(12H), 3.39~4.33(46H)

[0646] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0647] [Example 24]

[0648] In the first and second reactions, HOCH2CF2CF2O (CF2CF2CF2O) is substituted l The compound shown in CF2CF2CH2OH is used instead of HOCH2CF2O (CF2CF2O). j (CF2O) k A compound represented by CF2CH2OH (wherein j representing the average degree of polymerization is 3.8, and k representing the average degree of polymerization is 0) (number average molecular weight 703, molecular weight distribution 1.1), and in the sixth reaction, 1.4 g of the compound represented by the above formula (20) was used instead of the compound represented by formula (11). Except for this, the operations up to the seventh reaction were carried out in the same manner as in Example 16.

[0649] To the reaction product obtained in the seventh reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed in the order of 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was refined by silica gel column chromatography. By performing the above steps, 2.6 g (number average molecular weight 2409, 1.1 mmol) of the compound represented by the above formula (2I) (Rf12i in formula (2I) is represented by formula (2IF). j2i representing the average degree of polymerization among the three Rf12i is 3.8, and k2i representing the average degree of polymerization is 0.) was obtained.

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

[0651] 1H-NMR (CD3COCD3): δ[ppm]=1.34~1.67(8H), 3.39~4.34(58H)

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

[0653] [Example 25]

[0654] In the sixth reaction, 1.2 g of the compound represented by the above formula (21) was used instead of the compound represented by formula (11). The same operations as in Example 16 were carried out to obtain 2.6 g (number average molecular weight 2407, 1.1 mmol) of the compound represented by the above formula (2J) (Rf22j in formula (2J) is represented by formula (2JF). l2j representing the average degree of polymerization among the three Rf22j is 2.0).

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

[0656] 1 H-NMR (CD3COCD3): δ[ppm]=3.39~4.34(60H), 5.14~5.22(2H), 5.26~5.35(2H), 5.87~5.91(2H) 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0657] [Example 26]

[0658] In the sixth reaction, 1.4 g of the compound represented by the above formula (22) was used instead of the compound represented by the formula (11). The same operations as in Example 16 were carried out to obtain 2.7 g (number average molecular weight 2463, 1.1 mmol) of the compound represented by the above formula (2K) (Rf22k in formula (2K) is represented by formula (2KF). l2k representing the average degree of polymerization among the three Rf22k is 2.0.).

[0659] The obtained compound (2K) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0660] 1 H-NMR (CD3COCD3): δ[ppm]=1.66~1.81(4H), 2.33~2.43(4H), 3.39~4.34(60H), 5.14~5.22(2H), 5.26~5.35(2H), 5.87~5.91(2H)

[0661] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0662] [Example 27]

[0663] In the sixth reaction, 1.4 g of the compound represented by the above formula (23) was used instead of the compound represented by the formula (20). The same operations as in Example 24 were carried out to obtain 2.7 g (number average molecular weight 2487, 1.1 mmol) of the compound represented by the above formula (2L) (Rf121 in formula (2L) is represented by formula (2LF). Among the three Rf121, j2l representing the average degree of polymerization is 3.8, and k2l representing the average degree of polymerization is 0.).

[0664] The obtained compound (2L) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0665] 1 H-NMR (CD3COCD3): δ[ppm]=1.15~1.25(4H), 2.00~2.10(4H), 3.39~4.34(60H)

[0666] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0667] [Example 28]

[0668] In the sixth reaction, 0.64 g (molecular weight 141, 4.5 mmol) of the compound represented by the following formula (32) was used instead of the compound represented by formula (18). The same operation as in Example 22 was carried out to obtain 2.6 g (number average molecular weight 2327, 1.1 mmol) of the compound represented by the above formula (2M) (Rf12m in formula (2M) is represented by formula (2MF). Among the three Rf12m, j2m representing the average degree of polymerization is 2.4, and k2m representing the average degree of polymerization is 2.4.).

[0669] The compound represented by formula (32) is synthesized by oxidizing the reaction product of 3-hydroxypropionitrile and 4-bromo-1-butene.

[0670]

[0671] The obtained compound (2M) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0672] 1 H-NMR (CD3COCD3): δ[ppm]=1.15~1.25(4H), 2.00~2.10(4H), 3.65~4.10(48H)

[0673] 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(14.4F), -77.7(6F), -80.3(6F), -91.0~-88.5(28.8F)

[0674] [Example 29]

[0675] The operations up to the seventh reaction were carried out in the same manner as in Example 16, except that 1.2 g of the compound represented by the above formula (25) was used instead of the compound represented by the formula (11) in the sixth reaction.

[0676] To the reaction product obtained in the seventh reaction, 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 obtained reaction solution was transferred little by little to a separatory funnel added with 100 mL of saline and extracted three times with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of saline, 100 mL of saturated sodium bicarbonate water, and 100 mL of saline in this order, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated and the residue was refined by silica gel column chromatography. By performing the above steps, 2.6 g (number average molecular weight 2383, 1.1 mmol) of the compound represented by the above formula (2N) (Rf22n in formula (2N) is represented by formula (2NF). l2n representing the average degree of polymerization among the three Rf22n is 2.0.) was obtained.

[0677] The obtained compound (2N) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0678] 1 H-NMR (CD3COCD3): δ[ppm]=1.66~1.85(8H), 3.31~4.43(58H)

[0679] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0680] [Example 30]

[0681] In the sixth reaction, 1.4 g of the compound represented by the above formula (26) was used instead of the compound represented by the formula (20). The same operations as in Example 24 were carried out to obtain 2.8 g (number average molecular weight 2523, 1.1 mmol) of the compound represented by the above formula (2O) (Rf12o in formula (2O) is represented by formula (2OF). Among the three Rf12o, j2o representing the average degree of polymerization is 3.8, and k2o representing the average degree of polymerization is 0.).

[0682] The obtained compound (2O) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0683] 1 H-NMR (CD3COCD3): δ[ppm]=1.80~1.90(6H), 3.32~4.39(64H), 7.25~7.41(2H)

[0684] 19 F-NMR (CD3COCD3): δ[ppm]=-78.6(6F), -81.3(6F), -90.0~-88.5(45.6F)

[0685] [Example 31]

[0686] In the third reaction, 1.4 mL (molecular weight 243, 7.4 mmol) of benzyl 4-bromobutyl ether (BnO(CH2)4Br (Bn represents benzyl)) was used instead of benzyl 2-bromoethyl ether. The same operation as in Example 2 was performed to obtain 2.4 g (number average molecular weight 2210, 1.1 mmol) of the compound represented by the above formula (3A) (Rf23a in formula (3A) is represented by formula (3AF). l3a representing the average degree of polymerization among the two Rf23a is 3.8).

[0687] The obtained compound (3A) is subjected to1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0688] 1 H-NMR (CD3COCD3): δ[ppm]=1.56~1.82(8H), 3.39~4.35(40H)

[0689] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0690] [Example 32]

[0691] In the third reaction, 1.9 g (molecular weight 259, 7.4 mmol) of 2-(2-benzyloxy)ethoxy-1-bromoethane (BnO(CH2)2O(CH2)2Br (Bn represents benzyl)) was used instead of benzyl 2-bromoethyl ether. The same operation as in Example 2 was performed to obtain 2.4 g (number average molecular weight 2226, 1.1 mmol) of the compound represented by the above formula (3B) (Rf23b in formula (3B) is represented by formula (3BF). l3b representing the average degree of polymerization among the two Rf23bs is 3.8).

[0692] The obtained compound (3B) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0693] 1 H-NMR (CD3COCD3): δ[ppm]=1.65~1.81(4H), 3.39~4.42(44H)

[0694] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(24F), -86.4(12F), -124.3(12F), -130.0~-129.0(12F)

[0695] When the compounds (1A) to (1O), (2A) to (2O), (3A), and (3B) of Examples 1 to 32 obtained in this manner are substituted into the formula (1), the values ​​of x, R 1 , R 2 , R 3 , R 4 The structures are shown in Tables 1 to 4.

[0696] [Table 1]

[0697]

[0698] [Table 2]

[0699]

[0700] [Table 3]

[0701]

[0702] [Table 4]

[0703]

[0704] [Comparative Example 1]

[0705] According to the method described in Patent Document 1, a compound represented by the following formula (4A) was synthesized.

[0706]

[0707] (Rf14a in formula (4A) is the PFPE chain represented by the above formula (4AF); among the two Rf14a, j4a representing the average degree of polymerization is 4.0, and k4a representing the average degree of polymerization is 4.0.)

[0708] [Comparative Example 2]

[0709] According to the method described in Patent Document 2, a compound represented by the following formula (4B) was synthesized.

[0710]

[0711] (Rf24b in formula (4B) is the PFPE chain represented by the above formula (4BF); among the two Rf24b, l4b indicating the average degree of polymerization is 3.8.)

[0712] [Comparative Example 3]

[0713] According to the method described in Patent Document 4, a compound represented by the following formula (4C) was synthesized.

[0714]

[0715] (Rf24c in formula (4C) is the PFPE chain represented by the above formula (4CF); among the two Rf24c, l4c representing the average degree of polymerization is 3.8.)

[0716] [Comparative Example 4]

[0717] According to the method described in Patent Document 4, a compound represented by the following formula (4D) was synthesized.

[0718]

[0719] (Rf24d in formula (4D) is the PFPE chain represented by the above formula (4DF); among the two Rf24d, l4d indicating the average degree of polymerization is 3.8.)

[0720] [Comparative Example 5]

[0721] According to the method described in Patent Document 4, a compound represented by the following formula (4E) was synthesized.

[0722]

[0723] (Rf24e in formula (4E) is the PFPE chain represented by the above formula (4EF); among the two Rf24e, l4e indicating the average degree of polymerization is 3.8.)

[0724] [Comparative Example 6]

[0725] According to the method described in Patent Document 3, a compound represented by the following formula (4F) was synthesized.

[0726]

[0727] (Rf24f in formula (4F) is the PFPE chain represented by the above formula (4FF); among the two Rf24f, l4f representing the average degree of polymerization is 3.8.)

[0728] [Comparative Example 7]

[0729] The compound represented by the following formula (4G) was synthesized by the method shown below.

[0730] Under nitrogen atmosphere, in a 200 mL eggplant flask, add HOCH2CF2CF2O (CF2CF2CF2O) l 20 g of a compound represented by CF2CH2OH (where l in the formula represents the average degree of polymerization and is 3.8) (number average molecular weight 909, molecular weight distribution 1.1), 2.4 g of a compound represented by the above formula (11), and 20 mL of tert-butyl alcohol were stirred at room temperature until the mixture became uniform. 0.67 g of potassium tert-butylate was further added to the uniform liquid, and the mixture was stirred at 70°C for 16 hours to react.

[0731] 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 8.9 g (molecular weight 1111, 8.0 mmol) of the compound represented by the following formula (33) as an intermediate.

[0732]

[0733] (In formula (33), l, which represents the average degree of polymerization, represents 3.8, and THP represents tetrahydropyranyl.)

[0734] Next, in a 200 mL eggplant flask under a nitrogen atmosphere, 8.9 g of the compound represented by formula (33) as the intermediate and 80 mL of N,N-dimethylformamide were added and stirred at room temperature until it became uniform. The uniform solution was cooled to 0°C, and 0.33 g of sodium hydride (purity 60%, molecular weight 24.00, 8.2 mmol) was added and stirred for 30 minutes. Then, 1.31 g of the compound represented by formula (34) (molecular weight 328.04, 4.0 mmol) was slowly added and stirred at room temperature for 24 hours to react.

[0735]

[0736] (In formula (34), THP represents tetrahydropyranyl.)

[0737] In the reaction solution obtained after the reaction, 10 mL of water was slowly added under ice cooling, and a little bit was transferred to a separatory funnel to which 100 mL of saturated saline solution was added, and 200 mL of a mixed solvent of ethyl acetate and hexane was extracted 3 times. Each organic layer extracted was washed with 100 mL of saline solution and dehydrated by anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated, and the residue was refined by silica gel column chromatography, and 3.7 g (molecular weight 2307, 1.6 mmol) of the compound shown in formula (35) was obtained as an intermediate.

[0738]

[0739] (Rf2 in formula (35) is the PFPE chain represented by the above formula; among the two Rf2, l representing the average degree of polymerization is 3.8.)

[0740] The compound represented by the formula (34) used in the above reaction is synthesized through five steps of reactions from the first reaction to the fifth reaction shown below.

[0741] One hydroxyl group of ethylene glycol is protected with a tetrahydropyranyl (THP) group (first reaction). Next, another hydroxyl group of ethylene glycol is converted into an aldehyde group by Sven oxidation to obtain an aldehyde compound represented by formula (36) (second reaction). The compound represented by formula (37) is obtained by subjecting the obtained aldehyde compound represented by formula (36) to a Knoevenagel condensation reaction with dimethyl malonate (third reaction). The compound represented by formula (38) is obtained by reducing the ester of the compound represented by formula (37) (fourth reaction). Then, the hydroxyl group of the compound represented by formula (38) is brominated by an Appel reaction to obtain a compound represented by formula (34) (fifth reaction).

[0742]

[0743] (In formula (36), THP represents tetrahydropyranyl.)

[0744] (In formula (37), THP represents tetrahydropyranyl.)

[0745] (In formula (38), THP represents tetrahydropyranyl.)

[0746] In a 200 mL eggplant flask under a nitrogen atmosphere, 3.7 g of the compound represented by the above formula (35), 30 mL of ethanol, and 0.10 g of palladium carbon (Pd / C) (5% Pd) were added, and the reaction system was placed in a hydrogen atmosphere, and stirred at room temperature for 16 hours. After removing Pd / C by diatomaceous earth filtration, 30 mL of 5% hydrogen chloride methanol solution was added to the filtrate and stirred at room temperature for 2 hours. After the reaction solution was neutralized with 125 mL of saturated sodium bicarbonate aqueous solution, it was extracted three times with 250 mL of ethyl acetate. The extracted organic layers were washed with 125 mL of saturated sodium chloride aqueous solution 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 3.0 g of the compound represented by the following formula (4G) (number average molecular weight 2138, 1.4 mmol).

[0747]

[0748] (Rf24g in formula (4G) is the PFPE chain represented by the above formula (4GF); among the two Rf24g, l4g indicating the average degree of polymerization is 3.8.)

[0749] The obtained compound (4G) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0750] 1 H-NMR (CD3COCD3); δ[ppm]=1.51~1.89(7H), 3.4~4.3(37H)

[0751] 19 F-NMR (CD3COCD3): δ[ppm]=-84.0~-83.0(30.4F), -86.4(8F), -124.3(8F), -130.0~-129.0(15.2F)

[0752] [Comparative Example 8]

[0753] According to the method described in Patent Document 6, a compound represented by the following formula (4H) was synthesized.

[0754]

[0755] (Rf14h in formula (4H) is a PFPE chain represented by the above formula (4HF); in the central Rf14h among the three Rf14h, j4h indicating the average degree of polymerization is 3.8, and k4h indicating the average degree of polymerization is 0; in the two Rf14h on the terminal side, j4h indicating the average degree of polymerization is 2.4, and k4h indicating the average degree of polymerization is 2.4.)

[0756] [Comparative Example 9]

[0757] According to the method described in Patent Document 7, a compound represented by the following formula (4I) was synthesized.

[0758]

[0759] (Rf14i in formula (4I) is the PFPE chain represented by the above formula (4IF); among the three Rf14i, j4i representing the average degree of polymerization is 3.8, and k4i representing the average degree of polymerization is 0.)

[0760] [Comparative Example 10]

[0761] The compound represented by the following formula (4J) was synthesized by the method described in Patent Document 5. j CF2CH2OH, and HOCH2CF2O (CF2CF2O) was used j (CF2O) kThe compound represented by CF2CH2OH (wherein j representing the average degree of polymerization is 2.4, and k representing the average degree of polymerization is 2.4) (number average molecular weight 699, molecular weight distribution 1.1) was obtained. In addition, the operation described in patent document 5 was carried out to obtain 2.5 g of the compound represented by the following formula (4J) (number average molecular weight 2253, 1.1 mmol).

[0762]

[0763] (Rf14j in formula (4J) is the PFPE chain represented by the above formula (4JF); among the three Rf14j, j4j representing the average degree of polymerization is 2.4, and k4j representing the average degree of polymerization is 2.4.)

[0764] The number average molecular weight (Mn) of the compounds of Examples 1 to 32 and Comparative Examples 1 to 10 obtained in this manner was measured by the above-mentioned method. The results are shown in Table 5 or Table 6.

[0765] [Table 5]

[0766]

[0767] [Table 6]

[0768]

[0769] Next, a lubricant layer forming solution was prepared by the method described below using the compounds obtained in Examples 1 to 32 and Comparative Examples 1 to 10. 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 32 and Comparative Examples 1 to 10.

[0770] "Lubricating layer forming solution"

[0771] The compounds obtained in Examples 1 to 32 and Comparative Examples 1 to 10 were dissolved in a fluorine-based solvent, Batorel (registered trademark) XF (trade name, manufactured by Mitsui Dupont Fluoro Chemical Co., Ltd.), and applied on the protective layer to a film thickness of The solution was diluted with Batler XF in a manner of 100% to prepare a lubricating layer forming solution.

[0772] "Magnetic recording media"

[0773] 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.

[0774] On the protective layer of the magnetic recording medium having each layer formed thereon, the lubricating layer forming solutions of Examples 1 to 32 and Comparative Examples 1 to 10 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.

[0775] 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.

[0776] (Film thickness measurement)

[0777] The film thickness of the lubricating layer of the magnetic recording media of Examples 1 to 32 and Comparative Examples 1 to 10 obtained in this manner was measured using FT-IR (trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific).

[0778] Next, the magnetic recording media of Examples 1 to 32 and Comparative Examples 1 to 10 were subjected to the following flying stability test and chemical substance resistance test.

[0779] (Floating stability test)

[0780] The following sliding test and credence measurement were performed, and the floating stability was evaluated based on the following evaluation criteria. The results are shown in Table 5 or Table 6.

[0781] "Sliding Test"

[0782] In the sliding test, it is checked whether there are protrusions on the surface of the magnetic recording medium. That is, when the magnetic recording medium is recorded and reproduced using a magnetic head, if there are protrusions on the surface of the magnetic recording medium with a height greater than the floating amount (the interval between the magnetic recording medium and the magnetic head), it may cause the magnetic head to collide with the protrusion and damage the magnetic head, or cause defects in the magnetic recording medium. In the sliding test, 50 pieces of magnetic recording media are checked for the presence or absence of protrusions with a height greater than the floating amount on the surface.

[0783] Specifically, the interval between the inspection head and the magnetic recording medium was set to 0.25 microinches, and the inspection head was moved on the magnetic recording medium. When a signal caused by a collision with a protrusion on the surface of the magnetic recording medium was output from the inspection head, the magnetic recording medium was judged to be defective, and the other signals were judged to be qualified. Furthermore, the number of magnetic recording media judged to be qualified among 50 magnetic recording media was used for evaluation.

[0784] "Reliability Measurement"

[0785] When the above-mentioned sliding test is carried out, the following phenomenon sometimes occurs: the noise temporarily increases, and even in the same place on the magnetic recording medium, the signal caused by the collision with the protrusion on the surface is detected or not detected in multiple measurements. Such a phenomenon is called reliability. Reliability is not detected as a protrusion in the sliding test and is not used to judge whether the sliding test is qualified or not. However, a temporary increase in noise in a sliding test generally indicates the unevenness of the lubricant layer or the presence of relatively soft foreign matter. Therefore, by performing a sliding test on the magnetic recording medium, the total number of times the reliability is detected is divided by the number of magnetic recording media (50 pieces) on which the sliding test is performed, thereby calculating the reliability average value, which is used as an indicator of the smoothness and cleanliness of the lubricant layer.

[0786] “Evaluation Benchmarks”

[0787] A: The number of qualified pieces in the sliding test is more than 45 and the average reliability value is less than 0.5

[0788] B: The number of qualified pieces in the sliding test is 45 or more and the reliability average is 0.5 or more and less than 1.0

[0789] C: The number of qualified pieces in the sliding test is 45 or more and the reliability average is 1.0 or more and less than 5.0

[0790] D: The number of qualified pieces in the sliding test is less than 45 or the reliability average is above 5.0

[0791] E: The number of qualified pieces in the sliding test is less than 45 and the reliability average is above 5.0

[0792] [Chemical resistance test]

[0793] The contamination of magnetic recording media by environmental substances that generate contaminants in a high temperature environment was investigated by the following method: Si ions were used as environmental substances, and the amount of Si adsorption was measured as the amount of contaminants generated by the environmental substances and contaminating the magnetic recording medium.

[0794] Specifically, the magnetic recording medium as the evaluation object was kept for 240 hours in the presence of siloxane-based Si rubber under a high temperature environment of 85°C and 0% humidity. Next, the Si adsorption amount present on the surface of the magnetic recording medium was analyzed and measured using secondary ion mass spectrometry (SIMS), and the degree of contamination caused by Si ions was evaluated as the Si adsorption amount. The evaluation of the Si adsorption amount was evaluated based on the following evaluation criteria using the numerical value when the result of Comparative Example 1 was set to 1.00. The results are shown in Tables 5 and 6.

[0795] “Evaluation Benchmarks”

[0796] A: Si adsorption is less than 0.60

[0797] B: Si adsorption amount is 0.60 or more and less than 0.75

[0798] C: Si adsorption amount is 0.75 or more and less than 0.90

[0799] D: Si adsorption amount is 0.90 or more and less than 1.00

[0800] E: Si adsorption is 1.00 or more

[0801] As shown in Table 5, the evaluations of the flying stability test and the chemical resistance test of the magnetic recording media of Examples 1 to 32 were all A or B. Therefore, it was confirmed that the magnetic recording media of Examples 1 to 32 had good flying stability of the magnetic head and high chemical resistance.

[0802] This is presumably because the compounds (1A) to (1O), (2A) to (2O), (3A), and (3B) that form the lubricating layers of the magnetic recording media of Examples 1 to 32 are less likely to generate polar groups that are not bonded to the functional groups (active sites) present on the protective layer. In other words, this is presumably because the R 1 and R 4 The polar groups and R 3 The primary hydroxyl groups in the lubricant layer are closely bonded to the protective layer with a high probability. As a result, it is estimated that the adhesion of the lubricant layer to the protective layer becomes good, and the inclusion of contaminants caused by polar groups contained in the lubricant layer that are not closely bonded to the protective layer is suppressed, thereby obtaining excellent chemical resistance and good floating stability of the magnetic head.

[0803] In addition, the evaluation of the floating stability test of the magnetic recording media of Examples 2 to 4, 7 to 9, 12, 13, 15, 17 to 19, 22 to 24, 27, 30 to 32 was A, and the floating stability of the magnetic head was particularly good. This is presumably because the magnetic recording media of the above-mentioned Examples have the use of R 1 and R 4 The lubricating layer is formed of a compound represented by any one of formulae (4-1) to (4-3) in which X is a polar group. Therefore, the lubricating layer has good adhesion to the protective layer and the lubricating layer is unlikely to float off the protective layer.

[0804] In addition, the magnetic recording media of Examples 10, 11, 25, and 26 are made of R 1 and R 4It is formed by a compound of formula (4-1) or (4-2) in which all X are alkenyl groups. Therefore, it is inferred that for the magnetic recording media of Examples 10, 11, 25, and 26, the alkenyl groups in the compound forming the lubricating layer interact with the π-π of the protective layer, thereby improving the adhesion of the protective layer and achieving good floating stability of the magnetic head.

[0805] Furthermore, the evaluation of the chemical substance resistance test of the magnetic recording media of Examples 1, 2, 7, 9, 13, 16, 17, 22, 24, 28, and 32 was A, which is good.

[0806] On the other hand, as shown in Table 6, the magnetic recording media of Comparative Examples 1 to 10 were rated C to E in at least one of the evaluation of the floating stability test and the evaluation of the chemical substance resistance test, which were inferior to Examples 1 to 32.

[0807] The magnetic recording medium of Comparative Example 1 was evaluated as C in the floating stability test and D in the chemical resistance test. The magnetic recording medium of Comparative Example 1 has a lubricating layer formed using compound (4A). The x and R in formula (1) of compound (4A) and compounds (1B), (3A), and (3B) used in the lubricating layers of Examples 2, 31, and 32 are 1 and R 4 However, compound (4A) is different from compounds (1B), (3A), and (3B) in that 3 The connecting group of contains a secondary hydroxyl group. Therefore, it is inferred that in Comparative Example 1, the corresponding R in formula (1) 3 The secondary hydroxyl group in the linking group is not bonded to the protective layer and is arranged in R 3 The two sides are equivalent to R 2 The PFPE chains floated from the protective layer, and the floating stability deteriorated. In addition, it is estimated that in Comparative Example 1, the contaminants adhered to the R in the formula (1) that floated from the protective layer. 3 The secondary hydroxyl group in the linking group is reduced, thereby deteriorating the chemical resistance.

[0808] The magnetic recording media of Comparative Examples 2 and 6 have lubricating layers formed using compounds (4B) and (4F). Compounds (4B) and (4F) are similar to compound (4A) in that R in formula (1) is 3 The connecting group of contains secondary hydroxyl group. Therefore, it is estimated that in Comparative Examples 2 and 6, as in Comparative Example 1, the corresponding R in Formula (1) 3 The secondary hydroxyl group in the linking group is not bonded to the protective layer, and the floating stability and chemical resistance are deteriorated.

[0809] The magnetic recording medium of Comparative Example 5 has a lubricating layer formed using the compound (4E). The compound (4E) corresponds to R in the formula (1).3 The linking group of contains one primary hydroxyl group and two secondary hydroxyl groups. Therefore, it is inferred that in Comparative Example 5, the corresponding R in formula (1) 3 The secondary hydroxyl group in the linking group is not bonded to the protective layer, and the floating stability and chemical resistance are deteriorated.

[0810] The magnetic recording medium of Comparative Example 3 has a lubricating layer formed using the compound (4C). 3 The two hydroxyl groups contained in the linking group are respectively bonded to adjacent carbon atoms. 3 One of the two hydroxyl groups in the connecting group is considered to be in a state that it is difficult to adhere to the protective layer. As a result, it is estimated that the floating stability of the magnetic head is poor, and contaminants caused by the hydroxyl group that is not closely attached to the protective layer are involved, resulting in poor chemical resistance.

[0811] The magnetic recording medium of Comparative Example 4 has a lubricating layer formed using the compound (4D). 3 The linking group of has a main chain portion forming a chain structure of a fluorinated ether compound and a side chain portion branched from the main chain portion and having a primary hydroxyl group at the front end. 3 In the linking group, the carbon atom of the main chain part to which the side chain part with the primary hydroxyl group at the front end is bonded is also bonded to an ethyl group (-CH2CH3). Therefore, it is presumed that the bonding between the primary hydroxyl group of the side chain part and the protective layer is hindered by the steric hindrance of the carbon atom of the main chain part to which the ethyl group is bonded, and the evaluation of the floating stability test is D. Moreover, compound (4D) is equivalent to R 3 There are two secondary hydroxyl groups in the connecting group of 3 The two secondary hydroxyl groups in the linking group are not bonded to the protective layer and float from the protective layer, and the chemical resistance and floating stability are deteriorated.

[0812] The magnetic recording media of Comparative Examples 2 to 6 and 10 have lubricating layers formed using compounds (4B) to (4F) and (4J). Compounds (4B) to (4F) and (4J) all have a lubricating layer equivalent to R 1 and R 4 The terminal groups of the two hydroxyl groups are the same, and the adjacent carbon atoms are bonded to hydroxyl groups. Since the two hydroxyl groups bonded to the adjacent carbon atoms are oriented in opposite directions, one of the two hydroxyl groups is considered to be in a state where it is difficult to adhere to the protective layer. As a result, it is estimated that hydroxyl groups that are not closely attached to the protective layer are easily generated, and the chemical resistance is deteriorated.

[0813] The magnetic recording medium of Comparative Example 7 was evaluated as B in the floating stability test and C in the chemical resistance test. The magnetic recording medium of Comparative Example 7 has a lubricating layer formed using compound (4G). The x and R in formula (1) of compound (4G) and compound (1A) used in the lubricating layer of Example 1 are 1 and R 4 Moreover, compound (4G) is equivalent to R 3 The linking group of has only one primary hydroxyl group. Therefore, it is presumed that in Comparative Example 7, the lubricating layer that can maintain a state of not floating from the protective layer is formed by the adhesion to the protective layer, and good floating stability is obtained.

[0814] In addition, the compound (4G) is equivalent to R 3 The linking group of has a main chain portion forming a chain structure of a fluorinated ether compound and a side chain portion consisting of -CH2CH2OH branched from the main chain portion and having a primary hydroxyl group at the front end. 3 The side chain part composed of -CH2CH2OH is directly bonded to the carbon atom of the main chain part. Therefore, the flexibility of the side chain part is insufficient, and -CH2CH2OH is considered to be in a state that is not easy to adhere to the protective layer. As a result, it is estimated that hydroxyl groups that are not closely attached to the protective layer are easily generated, and contaminants caused by the hydroxyl groups that are not closely attached to the protective layer are involved, resulting in poor resistance to chemical substances.

[0815] The magnetic recording medium of Comparative Example 8 was evaluated as C in the floating stability test and C in the chemical resistance test. The magnetic recording medium of Comparative Example 8 has a lubricating layer formed using compound (4H). The x and R in formula (1) of compound (4H) and compound (2A) used in the lubricating layer of Example 16 are 1 and R 4 However, compound (4H) is different from compound (2A) in that 3 The connecting group of contains a secondary hydroxyl group. Therefore, it is inferred that in Comparative Example 8, the corresponding R in formula (1) 3 The secondary hydroxyl group in the linking group is not bonded to the protective layer and is arranged in R 3 The two sides are equivalent to R 2 The PFPE chains floated from the protective layer, and the floating stability deteriorated. In addition, it is estimated that in Comparative Example 8, the contaminants adhered to the R in the formula (1) that floated from the protective layer. 3 The secondary hydroxyl group in the linking group is reduced, thereby deteriorating the chemical resistance.

[0816] The magnetic recording media of Comparative Examples 9 and 10 have lubricating layers formed using Compounds (4I) and (4J). Compounds (4I) and (4J) are similar to Compound (4H) in the presence of a lubricating agent corresponding to R 3 The connecting group of contains secondary hydroxyl group. Therefore, it is estimated that Comparative Examples 9 and 10 are similar to Comparative Example 8, and the corresponding R in Formula (1) 3 The secondary hydroxyl group in the linking group is not bonded to the protective layer, and the floating stability and chemical resistance are deteriorated.

[0817] One terminal of the compound (4I) forming the lubricating layer of Comparative Example 9 is composed of a hydroxyl group bonded to a perfluoropolyether chain via a methylene group (-CH2-). Therefore, it is estimated that the adhesion of the lubricating layer as a whole to the protective layer of the magnetic recording medium of Comparative Example 9 is insufficient, and the evaluations of the floating stability test and the chemical resistance test are both E.

[0818] Industrial Availability

[0819] By using the lubricant for a magnetic recording medium containing the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer which has excellent chemical resistance and good flying stability of a magnetic head even if the lubricating layer is thin.

[0820] Explanation of symbols

[0821] 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, characterized in that It is represented by the following formula (1): R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1) In formula (1), R 1 and R 4 Each independently represents an end group containing 2 or 3 polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms bonded to the polar groups are bonded to each other via a linking group containing a carbon atom not bonded to the polar group; x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; 2 or 3 R 2 They may be partially or completely the same, or they may be different; R 3 is a divalent linking group represented by the following formula (3-1) or (3-2); when x is 2, two R 3 They can be the same or different; In formula (3-1), a represents an integer of 2 to 4; y1 represents an integer of 1 to 3; y2 represents an integer of 1 to 3; at least one of y1 and y2 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 4 The side methylene bond is bonded to the bond; In formula (3-2), y3 represents an integer of 1 to 3; y4 represents an integer of 1 to 3; at least one of y3 and y4 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 4 The side methylene bond is bonded to the bond.

2. The fluorinated ether compound according to claim 1, wherein in the formula (1), -R 1 and -R 4 Each is independently any one of the following formulas (4-1) to (4-3), In formula (4-1), b is an integer of 1 to 2, and c is an integer of 0 to 3; X in formula (4-1) is an alkenyl group, an alkynyl group, or a polar group; when b is 1, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X; In formula (4-2), d is an integer of 1 to 3, e is an integer of 0 to 1, and f is an integer of 0 to 3; X in formula (4-2) is an alkenyl group, an alkynyl group, or a polar group; when e is 0, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X; In formula (4-3), g is an integer from 0 to 1, h is an integer from 1 to 3, and i is an integer from 1 to 3; X in formula (4-3) is an alkenyl group, an alkynyl group, or a polar group; when g is 0, X is a polar group; when X is an alkenyl group or an alkynyl group, the carbon atom constituting the unsaturated bond in X is bonded to the methylene group adjacent to X. 3 . The fluorine-containing ether compound according to claim 2 , wherein in the formulae (4-1) to (4-3), X is any one of a hydroxyl group, a group having an amide bond, a cyano group, and —CH═CH 2 .

4. The fluorine-containing ether compound according to any one of claims 1 to 3, wherein x in the formula (1) is 1, and R 1 With R 4 Same, 2 R 2 same.

5. The fluorine-containing ether compound according to any one of claims 1 to 3, wherein x in the formula (1) is 2, and R 1 With R 4 Same, 3 Rs 2 same.

6. The fluorinated ether compound according to claim 5, wherein the two R 3The atoms contained in the R are located in the center of the molecular chain structure. 2 are symmetrically configured.

7. The fluorinated ether compound according to any one of claims 1 to 3, wherein two or three R in the formula (1) are 2 Each independently is a perfluoropolyether chain represented by the following formula (5), -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(5) In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein, w2, w3, w4, and w5 are not all 0 at the same time; w1 and w6 are average values ​​of numbers representing CF2, and each independently represents 1 to 3; there is no particular restriction on the arrangement order of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) as repeating units in formula (5).

8. The fluorinated ether compound according to any one of claims 1 to 3, 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 (6-1) to (6-4), -CF2-(OCF2CF2) j -(OCF2) k -OCF2-(6-1) In formula (6-1), j and k represent the average degree of polymerization, j represents 0.1 to 20, and k represents 0 to 20; -CF2CF2-(OCF2CF2CF2) l -OCF2CF2-(6-2) In formula (6-2), l represents the average degree of polymerization, which is 0.1 to 15; -CF2CF2CF2-(OCF2CF2CF2CF2) m -OCF2CF2CF2-(6-3) In formula (6-3), m represents the average degree of polymerization and is 0.1 to 10; -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(6-4) In formula (6-4), 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. 9 . The fluorine-containing ether compound according to claim 1 , which has a number average molecular weight in the range of 500 to 10,000.

10. A lubricant for a magnetic recording medium, characterized in that: The fluorine-containing ether compound according to any one of claims 1 to 3.

11. A magnetic recording medium, 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 any one of claims 1 to 3. 12 . The magnetic recording medium according to claim 11 , wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm.

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