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 (wherein x is an integer from 1 to 2; r2 is a perfluoropolyether chain; at least one of the x R3 groups is represented by formula (2-1) or (2-2); r1 and R4 are terminal groups having 2-4 polar groups, wherein the number of carbon atoms, which are the shortest distance between carbon atoms to which adjacent polar groups are bonded, is 1-9, and each has an oxygen atom bonded to a methylene group bonded to R2. > # 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. 2022-122139 filed in Japan on July 29, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] In order to increase the recording density in 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 magnetic recording medium in which a recording layer is formed on a substrate and a protective layer composed 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. However, only by arranging the protective layer on the recording layer, the durability of the magnetic recording medium cannot be fully obtained. Therefore, generally speaking, a lubricant is applied on the surface of the protective layer to form a lubricating layer.

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

[0006] For example, Patent Documents 1 and 2 disclose a fluorinated ether compound having a skeleton in which two perfluoropolyether chains are connected via a divalent connecting group in which a methylene group (-CH2-) is connected to both ends of a glycerol structure (-O-CH2-CH(OH)-CH2-O-), and terminal groups as organic groups having polar groups are connected to both ends via methylene groups.

[0007] In addition, Patent Documents 3 to 5 disclose a fluorinated ether compound having a skeleton in which two perfluoropolyether chains are connected via a divalent connecting group including a methylene group (-CH2-) and a group in which one hydrogen atom of the methylene group is substituted by a hydroxyl group (-CH(OH)-), and having two hydroxyl groups, and having terminal groups of organic groups having polar groups connected to both ends via methylene groups.

[0008] In addition, Patent Document 6 discloses a fluorine-containing ether compound having a skeleton having two or three perfluoropolyether chains connected via a divalent connecting group including a methylene group (-CH2-) and a group in which one hydrogen atom of the methylene group is substituted by a hydroxyl group (-CH(OH)-), and having two hydroxyl groups, and having terminal groups of organic groups having polar groups connected to both ends via methylene groups.

[0009] Furthermore, Patent Documents 7 and 8 disclose a fluorinated ether compound having a skeleton in which three perfluoropolyether chains are connected via a divalent connecting group containing a methylene group (-CH2-) and a group in which one hydrogen atom of the methylene group is substituted by a hydroxyl group (-CH(OH)-), and having one hydroxyl group, and having hydroxyl groups or terminal groups of an organic group having a polar group connected to both sides thereof via methylene groups.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: U.S. Patent No. 10540997

[0013] Patent Document 2: International Publication No. 2021 / 251335

[0014] Patent Document 3: International Publication No. 2021 / 020066

[0015] Patent Document 4: Japanese Patent No. 6804981

[0016] Patent Document 5: Japanese Patent No. 5743438

[0017] Patent Document 6: U.S. Patent No. 10262685

[0018] Patent Document 7: International Publication No. 2018 / 116742

[0019] Patent Document 8: International Publication No. 2017 / 145995 Summary of the invention

[0020] Problems to be solved by the invention

[0021] In a magnetic recording and reproducing device, it is required to further reduce the flying height of the magnetic head.

[0022] Yet, generally speaking, if the floating amount of magnetic head is made small, magnetic head and substrate collide easily. That is, there is a tendency that the floating stability of magnetic head decreases. In addition, if the floating amount of magnetic head is made small, the fluorine-containing ether compound in the lubricating layer sometimes adheres to the adhesion (pickup) of magnetic head.

[0023] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluorine-containing ether compound which can form a lubricating layer having excellent floating stability and capable of suppressing sticking and can be suitably used as a material for a lubricant for a magnetic recording medium.

[0024] Another object of the present invention is to provide a lubricant for a magnetic recording medium which contains the fluorine-containing ether compound of the present invention and can form a lubricating layer having good floating stability and a high adhesion suppressing effect.

[0025] 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, which has excellent flying stability of a magnetic head and a high sticking suppression effect.

[0026] Means for solving problems

[0027] The present invention includes the following aspects.

[0028] A first aspect of the present invention provides the following fluorine-containing ether compound.

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

[0030] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1)

[0031] (In formula (1), x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; (x+1) R 2 They may be partly or completely the same, or they may be different; R 3 is a divalent linking group having a hydroxyl group; x R 3 At least one of them is a divalent linking group represented by the following formula (2-1) or (2-2); when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 2 to 4 polar groups, and the number of carbon atoms for the shortest distance between carbon atoms bonded to adjacent polar groups is 1 to 9 and has a carbon atom bonded to R 2 The terminal group of the oxygen atom of the methylene group; R 1 and R 4 They can be the same or different.)

[0032]

[0033] (In formula (2-2), l represents an integer of 1 to 2.)

[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 R in the above formula (1) 1and R 4 Each independently contains at least one polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond.

[0036] [3] The fluorinated ether compound according to [1], wherein R in the above formula (1) 1 and R 4 Each independently represents a terminal group represented by any one of the following formulae (3-1) to (3-4).

[0037]

[0038] (In formula (3-1), p represents an integer of 0 to 3, r represents an integer of 1 to 5, and the total value of p and r is 1 to 5; q represents an integer of 0 to 2; and A represents a polar group.)

[0039] (In formula (3-2), s represents an integer from 0 to 2, and t represents an integer from 1 to 5.)

[0040] (In formula (3-3), u represents an integer of 2 to 4; Y represents a linear alkylene group which may have an ether oxygen, or a single bond; when Y is the above alkylene group, the total number of carbon atoms and oxygen atoms possessed by Y is 1 to 5.)

[0041] (In formula (3-4), v represents an integer of 1 to 3; B represents a polar group in which a hydrogen atom at any position of the benzene ring is substituted.)

[0042] [4] The fluorinated ether compound according to any one of [1] to [3], wherein R in the formula (1) 1 The polar group and R 4 The total number of polar groups possessed is 4 to 6.

[0043] [5] The fluorinated ether compound according to any one of [1] to [4], wherein R in the formula (1) 1 With R 4 same.

[0044] [6] The fluorinated ether compound according to any one of [1] to [5], wherein the x R in the formula (1) 3 At least one of them is represented by the above formula (2-1).

[0045] [7] The fluorinated ether compound according to any one of [1] to [6], wherein the (x+1)th R in the formula (1) 2 Each is independently a perfluoropolyether chain represented by the following formula (4).

[0046] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O)w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0047] (In formula (4), 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 (4).)

[0048] [8] The fluorinated ether compound according to any one of [1] to [6], wherein the (x+1)th R in the formula (1) 2 Each independently represents any one selected from the group consisting of perfluoropolyether chains represented by the following formulae (4-1) to (4-4).

[0049] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1)

[0050] (In formula (4-1), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0051] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2)

[0052] (In formula (4-2), j represents the average degree of polymerization and is 1 to 15.)

[0053] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3)

[0054] (In formula (4-3), k represents the average degree of polymerization and is 1 to 10.)

[0055] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4)

[0056] (In formula (4-4), w8 and w9 represent the average degree of polymerization, and each independently represents 1 to 20; w7 and w10 represent the average value of the number of CF2, and each independently represents 1 to 2.)

[0057] [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.

[0058] A second aspect of the present invention provides the following lubricant for a magnetic recording medium.

[0059]

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

[0060] A third aspect of the present invention provides the following magnetic recording medium.

[0061]

[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,

[0062] The lubricating layer contains the fluorine-containing ether compound described in any one of [1] to [9].

[0063] The magnetic recording medium according to the third aspect of the present invention preferably has the feature described in the following

[12] .

[0064]

[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.

[0065] Effects of the Invention

[0066] 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.

[0067] 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 floating stability and a high adhesion suppressing effect.

[0068] The magnetic recording medium of the present invention has a lubricating layer comprising a fluorine-containing ether compound of the present invention. Therefore, the magnetic recording medium of the present invention has good floating stability of the magnetic head, high adhesion suppression effect, and excellent reliability and durability. In addition, the magnetic recording medium of the present invention has a lubricating layer that can suppress adhesion and has good floating stability of the magnetic head, so the floating amount of the magnetic head can be further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention. DETAILED DESCRIPTION

[0070] The present inventors have conducted intensive studies in order to solve the above-mentioned problems as described below.

[0071] In the past, as the material of the lubricant for magnetic recording media (hereinafter, sometimes abbreviated as "lubricant") applied to the surface of the protective layer, it is preferred to use a fluorine-containing ether compound having a chain structure containing a plurality of perfluoropolyether chains, and an adsorption site having a polar group disposed at the end of the chain structure and between the perfluoropolyether chains. The adsorption site in the fluorine-containing ether compound combines with the active point on the protective layer to improve the adhesion of the lubricating layer to the protective layer.

[0072] However, when a thin lubricating layer is formed on a protective layer using a conventional lubricant, it is difficult to realize a lubricating layer that has good flying stability of a magnetic head and is less likely to cause sticking, as described below.

[0073] That is, the adsorption sites of the fluorinated ether compounds in the lubricating layer that do not interact with the active points on the protective layer float up to form lumps, which reduces the smoothness of the lubricating layer. The lumps formed by the fluorinated ether compounds in the lubricating layer collide with the magnetic head and reduce the floating stability.

[0074] In addition, there is an adsorption site in the fluorine-containing ether compound contained in the lubricating layer that does not interact with the active point on the protective layer, and the adsorption site is adsorbed to the magnetic head floating near the adsorption site. Furthermore, with the adsorption site adsorbed to the magnetic head as a starting point, the fluorine-containing ether compound is captured by the magnetic head and attached, causing adhesion.

[0075] Therefore, the present inventors focused on the adsorption sites of the fluorinated ether compound contained in the lubricating layer that can interact with the active sites on the protective layer, and repeatedly conducted in-depth studies as shown below in order to realize a fluorinated ether compound that is less likely to produce adsorption sites that do not participate in the interaction with the active sites on the protective layer in the lubricating layer.

[0076] The present inventors first studied the arrangement of a plurality of adsorption sites of a fluorinated ether compound that can interact with active sites on a protective layer, and the strength of interaction between each adsorption site and the active site on the protective layer.

[0077] As a result, it was found that it is necessary to prepare a fluorine-containing ether compound having adsorption sites (hereinafter sometimes referred to as "terminal adsorption sites") arranged at both ends of a chain structure comprising a plurality of perfluoropolyether chains, and having an adsorption site (hereinafter sometimes referred to as "central adsorption site") arranged at least one between adjacent perfluoropolyether chains, the strength of the interaction between the terminal adsorption sites and the active sites on the protective layer and the strength of the interaction between the central adsorption sites and the active sites on the protective layer being appropriately balanced, and the terminal adsorption sites and the central adsorption sites being able to interact with the active sites on the protective layer with sufficient strength.

[0078] That is, if the interaction between the terminal adsorption site and the active points on the protective layer is too strong compared to the interaction between the central adsorption site and the active points on the protective layer, the active points on the protective layer that the central adsorption site can interact with are insufficient, resulting in a central adsorption site that does not participate in the interaction with the active points on the protective layer. As a result, the vicinity of the central adsorption site floats up and becomes a block, the smoothness of the lubricating layer is reduced, and the floating stability is reduced. In addition, if the interaction between the central adsorption site and the active points on the protective layer is too strong compared to the interaction between the terminal adsorption site and the active points on the protective layer, the active points on the protective layer that the terminal adsorption site can interact with are insufficient, resulting in a terminal adsorption site that does not participate in the interaction with the active points on the protective layer. In this case, the vicinity of the terminal adsorption site floats up and is adsorbed to the magnetic head that floats near the terminal adsorption site on the lubricating layer, resulting in adhesion.

[0079] Therefore, the inventors have repeatedly studied the structures of terminal adsorption sites and central adsorption sites that can interact with the active points on the protective layer with sufficient strength, and in which the strength of the interaction between the terminal adsorption sites and the active points on the protective layer is appropriately balanced with the strength of the interaction between the central adsorption sites and the active points on the protective layer.

[0080] As a result, it was found that the fluorinated ether compound can be prepared by configuring a terminal group having 2 to 4 polar groups, wherein the number of carbon atoms in the shortest distance between carbon atoms to which adjacent polar groups are bonded is 1 to 9 and the terminal group has an oxygen atom bonded to a methylene group bonded to a perfluoropolyether chain as a terminal adsorption site, and configuring a divalent connecting group represented by formula (2-1) or (2-2) as a central adsorption site.

[0081] The divalent linking group represented by the formula (2-1) or (2-2) is a highly flexible divalent linking group having two or three hydroxyl groups.

[0082] More specifically, since the perfluoropolyether chain is a sterically bulky skeleton, the adjacent perfluoropolyether chains disposed on both sides of the divalent linking group can easily inhibit the adsorption of the hydroxyl groups of the divalent linking groups disposed between the adjacent perfluoropolyether chains to the protective layer.

[0083] For example, when a divalent linking group having only one hydroxyl group is configured as the central adsorption site instead of the divalent linking group represented by formula (2-1) or (2-2), the adsorption of the hydroxyl group to the protective layer is sometimes hindered by the adjacent perfluoropolyether chains configured on both sides of the divalent linking group, and the divalent linking group cannot participate in the interaction with the active points on the protective layer.

[0084] In addition, when a divalent linking group having a rigid structure is arranged as the central adsorption site, even if the divalent linking group has a plurality of hydroxyl groups, it may not be able to participate in the interaction with the active point on the protective layer. This is because since the divalent linking group having a rigid structure cannot move freely, when the adjacent perfluoropolyether chains arranged on both sides of the divalent linking group move molecules, they may move in conjunction with the perfluoropolyether chains and separate from the protective layer.

[0085] In addition, when a divalent linking group having a number of atoms forming a chain structure of less than 6 is arranged as a central adsorption site, the distance between adjacent perfluoropolyether chains is short. Therefore, the adsorption of the hydroxyl groups possessed by the divalent linking group to the protective layer is easily further hindered by the perfluoropolyether chain, and the hydroxyl groups possessed by the divalent linking group are less likely to be adsorbed to the protective layer.

[0086] In contrast, for the above-mentioned fluorine-containing ether compound, a divalent linking group shown in formula (2-1) or (2-2) is configured as a central adsorption site between at least one of the adjacent perfluoropolyether chains. The divalent linking group shown in formula (2-1) or (2-2) has 2 or 3 hydroxyl groups, and the number of atoms forming the chain structure is 6 or more. Moreover, the number of carbon atoms between the oxygen atoms of the ether bond in the chain structure of the divalent linking group shown in formula (2-1) or (2-2) is 3 or 4, and both ends are connected to the perfluoropolyether chain through ether bonds via methylene. Therefore, it has moderate softness.

[0087] Therefore, for the above-mentioned fluorine-containing ether compound, the distance between adjacent perfluoropolyether chains is fully ensured by the divalent linking group shown in formula (2-1) or (2-2) configured as the central adsorption site, and the adsorption of the hydroxyl group possessed by the divalent linking group to the protective layer is not easily hindered by the perfluoropolyether chain. In addition, even if the adsorption of one hydroxyl group possessed by the above-mentioned divalent linking group to the protective layer is hindered due to the large volume of the adjacent perfluoropolyether chains on both sides of the divalent linking group shown in formula (2-1) or (2-2), the other one or two hydroxyl groups can also be adsorbed on the protective layer. Moreover, since the divalent linking group shown in formula (2-1) or (2-2) has sufficient flexibility, even if the adjacent perfluoropolyether chain molecules configured on both sides of the above-mentioned divalent linking group move, they can move freely and independently without being linked to the perfluoropolyether chain. Therefore, the interaction between the divalent linking group represented by formula (2-1) or (2-2) and the active point on the protective layer is not easily affected by the molecular motion of the adjacent perfluoropolyether chains respectively arranged on both sides of the divalent linking group. Therefore, the divalent linking group represented by formula (2-1) or (2-2) as the central adsorption site is easily involved in the interaction with the active point on the protective layer.

[0088] However, even in the case of a fluorinated ether compound in which a divalent linking group represented by formula (2-1) or (2-2) is arranged as a central adsorption site between at least one of the adjacent perfluoropolyether chains, in the case of a fluorinated ether compound in which terminal groups are bonded to both ends of a chain structure comprising a plurality of perfluoropolyether chains, each of which has 2 to 4 polar groups and to which the shortest distance between carbon atoms to which adjacent polar groups are bonded is 1 to 9 and to which the oxygen atom of a methylene group bonded to the perfluoropolyether chain is bonded, the terminal groups may not participate in the interaction with the active sites on the protective layer.

[0089] This is presumably because the number of active points on the protective layer that can interact with the fluorinated ether compound is limited. That is, since the divalent linking group represented by formula (2-1) or (2-2) that can strongly interact with the active points on the protective layer is arranged as the central adsorption site, the central adsorption site is more likely to preferentially interact with the active points on the protective layer than the terminal groups. As a result, it is presumed that the terminal groups, which have weaker adsorption force with the active points on the protective layer than the central adsorption site, are less likely to participate in the interaction with the active points on the protective layer.

[0090] In contrast, for the fluorinated ether compound configured with the above-mentioned terminal group as the terminal adsorption site and the divalent linking group shown in formula (2-1) or (2-2) as the central adsorption site, the terminal adsorption site is a terminal group having 2 to 4 polar groups, with adjacent polar groups at an appropriate distance from each other, and forming an ether bond with the methylene group bound to the perfluoropolyether chain. Therefore, the 2 to 4 polar groups contained in the terminal adsorption site are not easily affected by the interaction between the adjacent polar groups, and can fully exert the adsorption force on the protective layer. Therefore, even if the divalent linking group shown in formula (2-1) or (2-2) is configured as the central adsorption site, the terminal adsorption site can interact with the active point on the protective layer.

[0091] Therefore, for a lubricating layer containing a fluorinated ether compound having 2 to 4 polar groups and having 1 to 9 carbon atoms as the shortest distance between carbon atoms bonded to adjacent polar groups and having an oxygen atom bonded to a methylene group bonded to a perfluoropolyether chain as a terminal adsorption site, and having a divalent linking group represented by formula (2-1) or (2-2) as a central adsorption site, the balance between the strength of interaction between the terminal adsorption site and the active point on the protective layer and the strength of interaction between the central adsorption site and the active point on the protective layer is appropriate, and adsorption sites that do not participate in the interaction with the active point on the protective layer are less likely to be generated in the fluorinated ether compound. As a result, it is estimated that the following effects <1> to <3> are obtained.

[0092] <1> It is possible to form a lubricating layer capable of suppressing a decrease in smoothness of the lubricating layer caused by a part of the fluorine-containing ether compound floating up to form lumps, thereby obtaining good floating stability.

[0093] <2> The adsorption site in the fluorine-containing ether compound that does not participate in the interaction with the active point on the protective layer can be prevented from being adsorbed to the magnetic head floating near the adsorption site. Therefore, a lubricating layer that is not prone to adhesion starting from the adsorption site adsorbed to the magnetic head can be formed.

[0094] <3> The central adsorption site and the terminal adsorption site of the fluorinated ether compound interact with the active points on the protective layer, thereby obtaining a good adsorption force on the protective layer. Therefore, even if the adsorption site that does not participate in the interaction with the active points on the protective layer is adsorbed on the magnetic head, it is not easy for the fluorinated ether compound to be captured by the magnetic head with the adsorption site adsorbed on the magnetic head as the starting point, which can inhibit adhesion.

[0095] Furthermore, the present inventors have confirmed that a lubricating layer having good floating stability and a high sticking suppression effect can be formed by using a lubricant containing the above-mentioned fluorinated ether compound, and thus have arrived at the present invention.

[0096] 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. In addition, the present invention is not limited to the embodiment shown below. The present invention can add, omit, replace, change in the scope of number, amount, position, ratio, material, formation etc. without exceeding the purpose of the present invention.

[0097] [Fluorinated ether compounds]

[0098] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

[0099] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1)

[0100] (In formula (1), x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; (x+1) R 2 They may be partly or completely the same, or they may be different; R 3 is a divalent linking group having a hydroxyl group; x R 3 At least one of them is a divalent linking group represented by the following formula (2-1) or (2-2); when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 2 to 4 polar groups, and the number of carbon atoms for the shortest distance between carbon atoms bonded to adjacent polar groups is 1 to 9 and has a carbon atom bonded to R 2 The terminal group of the oxygen atom of the methylene group; R 1 and R 4 They can be the same or different.)

[0101]

[0102] (In formula (2-2), 1 represents an integer from 1 to 2.)

[0103] The fluorine-containing ether compound of this embodiment has R as shown in formula (1). 3 The divalent linking group shown in 2 The perfluoropolyether chains (hereinafter sometimes referred to as "PFPE chains") shown in FIG. 1 are connected via methylene groups. R is bonded to one end of the skeleton via a methylene group. 1 The terminal group shown in FIG. 1 is bonded to R via a methylene group at the other end of the skeleton. 4 The terminal groups are shown.

[0104] In the fluorine-containing ether compound represented by formula (1), x represents an integer of 1 to 2. Since x is an integer of 1 to 2, R 2 The number of PFPE chains (x+1) shown is 2 or 3, which is consistent with R 2 The number of PFPE chains shown is different from that of the compound with one PFPE chain. 2 R 3 Thus, it is possible to obtain a divalent linking group having a hydroxyl group. 2 Compared with the compound having one PFPE chain, the lubricating layer has excellent adhesion to the protective layer. 2 Compared with compounds with 4 or more PFPE chains, the molecules do not become too large and can move freely. Therefore, it is easy to wet and spread on the protective layer, and it is easy to obtain a lubricating layer with a uniform film thickness. In addition, since x is an integer of 1 to 2, it is arranged in R 2 R 3 The number becomes 1 or 2. Therefore, -R in formula (1) 2 [-CH2-R 3 -CH2-R 2 ] x -The number of hydroxyl groups it possesses is easy to become appropriate, and it is easy to obtain a lubricating layer with good adhesion to the protective layer. In addition, the fluorinated ether compound represented by formula (1) can prevent the interaction between polar groups in the molecule, and the polar groups possessed by the fluorinated ether compound are not easy to agglomerate with each other, compared with the case where x is 3 or more. Therefore, a lubricating layer with good floating stability and high adhesion inhibition effect can be formed.

[0105] (R 3 The divalent linking group shown

[0106] In the fluorine-containing ether compound represented by formula (1), x R 3 Each independently represents a divalent linking group having a hydroxyl group. In the fluorine-containing ether compound represented by formula (1), since R 3 Since the fluorine-containing ether compound has a hydroxyl group, when a lubricating layer is formed on a protective layer using a lubricant containing the fluorine-containing ether compound, a suitable interaction occurs between the lubricating layer and the protective layer.

[0107] In the fluorine-containing ether compound represented by formula (1), x R 3 At least one of them is a divalent linking group represented by formula (2-1) or (2-2). That is, when x is 1, R 3 is a linking group represented by formula (2-1) or (2-2). When x is 2, two R 3 One or two R 3It is a divalent linking group represented by formula (2-1) or (2-2).

[0108] The divalent linking groups represented by formula (2-1) and (2-2) both have oxygen atoms at both ends of the chain structure and are bonded to R through ether bonds. 3 The divalent linking group shown in formula (2-1) has a methylene bond. The number of carbon atoms between the oxygen atoms of the ether bond formed in the chain structure of the divalent linking group shown in formula (2-1) is 4, and the number of carbon atoms between the adjacent oxygen atoms of the ether bond formed in the chain structure of the divalent linking group shown in formula (2-2) is 3. The oxygen atoms contained in the chain structure of the divalent linking group shown in formula (2-1) and (2-2) form ether bonds to impart moderate flexibility to the fluorine-containing ether compound shown in formula (1), thereby increasing the affinity of the hydroxyl groups possessed by the divalent linking groups shown in formula (2-1) and (2-2) with the protective layer. In addition, since the divalent linking groups shown in formula (2-1) and (2-2) have sufficient flexibility, even if the perfluoropolyether chains adjacent to the two sides thereof are arranged to move molecules, they are not linked to the perfluoropolyether chains and can move freely independently. Therefore, the divalent linking group represented by formula (2-1) or (2-2) is less susceptible to the molecular motion of the perfluoropolyether chains bonded to both sides thereof via methylene groups and is more likely to participate in the interaction with the active sites on the protective layer.

[0109] The number of atoms forming a chain structure of the divalent linking groups shown in formula (2-1) and (2-2) is 6 or more. Specifically, the number of atoms forming a chain structure of the divalent linking groups shown in formula (2-1) is 6. The number of atoms forming a chain structure of the divalent linking groups shown in formula (2-2) is 9 when l in formula (2-2) is 1, and is 13 when 1 is 2. Therefore, for the above-mentioned fluorine-containing ether compound, the distance between adjacent perfluoropolyether chains is fully ensured by the divalent linking groups shown in formula (2-1) or (2-2), and the adsorption of the hydroxyl groups possessed by the divalent linking groups to the protective layer is not easily hindered by the perfluoropolyether chains.

[0110] The divalent linking group represented by formula (2-1) has two hydroxyl groups. The divalent linking group represented by formula (2-2) has two or three hydroxyl groups. Since the divalent linking group represented by formula (2-1) or (2-2) has two or more hydroxyl groups, the adhesion (closeness) between the lubricating layer containing the fluorinated ether compound and the protective layer is good. That is, even if the adsorption of one hydroxyl group in formula (2-1) or (2-2) to the protective layer is hindered due to the large volume of the adjacent perfluoropolyether chains on both sides, the other one or two hydroxyl groups can also be adsorbed on the protective layer. Moreover, since the number of hydroxyl groups possessed by the above-mentioned divalent linking group is 3 or less, in the magnetic recording medium having a lubricating layer containing a fluorinated ether compound, the ability to bond to R 1 and R 4The active points on the protective layer that the terminal groups interact with are insufficient, resulting in adsorption sites that do not participate in the interaction with the active points on the protective layer. Therefore, it is possible to prevent adhesion caused by the adsorption sites that do not participate in the interaction with the active points on the protective layer floating near the adsorption sites and adhering to the magnetic head floating on the lubricating layer. In order to more effectively prevent the occurrence of adhesion, the number of hydroxyl groups possessed by the above-mentioned divalent linking group is preferably 2.

[0111] In the divalent linking group shown in formula (2-1), the carbon atoms to which the two hydroxyl groups in formula (2-1) are bound are directly bound to each other. Therefore, compared with the case where the carbon atoms to which the hydroxyl groups are bound are bound to each other via a rigid alkylene chain composed of a plurality of methylene groups, the two hydroxyl groups in formula (2-1) can move flexibly. Therefore, even if the perfluoropolyether chains arranged on both sides undergo molecular motion, the two hydroxyl groups in the divalent linking group shown in formula (2-1) can also move freely and independently, making it easy to maintain the interaction between the hydroxyl groups in the divalent linking group and the protective layer.

[0112] In addition, in the divalent linking group shown in formula (2-1), since the two hydroxyl groups are close, the orientation of the two hydroxyl groups in the same direction is restricted relative to the alkylene chain containing the carbon atoms to which these hydroxyl groups are bound. In other words, the two hydroxyl groups contained in the divalent linking group shown in formula (2-1) are easily oriented in different directions relative to the alkylene chain containing the carbon atoms to which these hydroxyl groups are bound. Therefore, the dipoles induced by the two hydroxyl groups are roughly reversed. Therefore, the sum of the dipole moments in the divalent linking group shown in formula (2-1) becomes smaller, and the surface free energy of the fluorinated ether compound becomes lower. As a result, the lubricating layer containing the fluorinated ether compound is not easy to bring in chemical pollutants brought into the environment, and has excellent resistance to chemical substances, which is preferred.

[0113] The divalent linking group shown in formula (2-2) includes a structure formed by connecting 2 to 3 glycerol structures (-O-CH2-CH(OH)-CH2-). Since the glycerol structure is soft, the structure shown in formula (2-2) formed by connecting 2 to 3 of them is extremely flexible, and the hydroxyl groups can move flexibly. Therefore, even when the perfluoropolyether chains arranged on both sides undergo molecular motion, the 2 to 3 hydroxyl groups in the divalent linking group shown in formula (2-2) can move freely and independently, making it easy to maintain the interaction between the hydroxyl groups in the divalent linking group and the protective layer.

[0114] In formula (2-2), 1 represents an integer of 1 to 2. When 1 is 1, the number of hydroxyl groups in the divalent linking group represented by formula (2-2) is 2. Therefore, the central part (-R 2 [-CH2-R 3 -CH2-R 2 ]x -) will not interact too strongly with the protective layer, thus preventing the terminal part (R 1 -CH2- and -CH2-R 4 ) The active points on the protective layer that can interact with each other are insufficient. Therefore, the fluorinated ether compound can form a lubricating layer in which the occurrence of adhesion caused by the floating of the terminal portion of the fluorinated ether compound is further suppressed.

[0115] When 1 in formula (2-2) is 2, the number of hydroxyl groups in the divalent linking group represented by formula (2-2) becomes 3. Therefore, the central part (-R 2 [-CH2-R 3 -CH2-R 2 ] x As a result, the center portion of the compound represented by formula (1) is prevented from departing from the protective layer and floating up, the smoothness of the lubricating layer is maintained, and the floating stability is improved.

[0116] In the fluorine-containing ether compound represented by formula (1), when x is 2 and two R 3 When only one of them is a divalent linking group represented by formula (2-1) or (2-2), one R that is not a divalent linking group represented by formula (2-1) or (2-2) 3 It only needs to be a divalent linking group having a hydroxyl group. 3 It is preferred to have oxygen atoms at both ends and to bond to R through ether bonds. 3 is not an R of a divalent linking group represented by formula (2-1) or (2-2). 3 The number of hydroxyl groups can be, for example, 1 to 3, preferably 1 or 2. As one R which is not a divalent linking group represented by formula (2-1) or (2-2), 3 , for example, a glycerol structure (-O-CH2-CH(OH)-CH2-O-) and the like can be mentioned.

[0117] In formula (1), when x is 2 and two R 3 When both R 3 They can be the same or different. 3 If the two R 3 If the above two compounds are the same, it becomes a fluorine-containing ether compound that can be easily produced, and therefore it is preferred.

[0118] (R 1 and R 4 terminal groups shown)

[0119] In the fluorine-containing ether compound represented by formula (1), R 1 and R 4 is a terminal group having 2 to 4 polar groups, and the number of carbon atoms with the shortest distance between carbon atoms bonded to adjacent polar groups is 1 to 9 and has a carbon atom bonded to R 2 The terminal group of the oxygen atom of the methylene group (-CH2-) is bonded.

[0120] In this embodiment, since R 1 and R 4 Since each of them is the above-mentioned terminal group, the lubricating layer containing the fluorine-containing ether compound represented by the formula (1) has good floating stability and a high adhesion suppressing effect.

[0121] In more detail, due to R 1 and R 4 The number of polar groups contained is 2 or more, so when a lubricating layer is formed on a protective layer using a lubricant containing a fluorinated ether compound, a suitable interaction occurs between the lubricating layer and the protective layer. As a result, the lubricating layer has excellent adhesion to the protective layer and a high adhesion suppression effect. In addition, due to R 1 and R 4 The number of polar groups contained is 4 or less, so in the lubricating layer containing the fluorinated ether compound, the polarity of the fluorinated ether compound is too high, the fluorinated ether compound aggregates to form lumps, and the smoothness of the lubricating layer is lost. In order to make the fluorinated ether compound less likely to aggregate, R 1 and R 4 The number of polar groups contained is preferably 3 or less, and most preferably 2. 1 and R 4 The number of polar groups contained is 2, and in the magnetic recording medium having a lubricating layer containing a fluorine-containing ether compound, R 1 and R 4 As a result, it is possible to form a structure that can prevent R 1 and R 4 A fluorine-containing ether compound that floats to form a lubricating layer with excellent floating stability.

[0122] R 1 and R 4 can be the same or different. 1 The number of polar groups and R 4The number of polar groups they have may be the same or different. In order to make the coating state of the protective layer by the fluorinated ether compound more uniform and to form a lubricating layer with better adhesion, R 1 The number of polar groups and R 4 The number of polar groups possessed is preferably the same.

[0123] R in formula (1) 1 The polar group and R 4 The total number of polar groups possessed is 4 to 8, preferably 4 to 6, more preferably 4 to 5, and most preferably 4.

[0124] If the total number of the polar groups is 4 or more, R 1 and R 4 The interaction between the polar group and the protective layer is stronger. 1 and R 4 The formed terminal group is separated from the protective layer, and the migration of the fluorine-containing ether compound from this portion as a starting point to the magnetic head is suppressed. Therefore, the fluorine-containing ether compound can obtain a lubricating layer with a high adhesion suppression effect.

[0125] In addition, if the total number of the above-mentioned polar groups is less than 6, it is not easy to produce polar groups that do not participate in the combination of the active points on the lubricating layer and the protective layer. Therefore, it is possible to prevent the polar groups that do not participate in the combination of the active points on the lubricating layer and the protective layer from agglomerating and becoming projections and colliding with the magnetic head. Therefore, a lubricating layer with more excellent floating stability can be formed, which is preferred.

[0126] In addition, R 1 and R 4 The number of carbon atoms with the shortest distance between the carbon atoms to which the adjacent polar groups are bonded is 1 to 9. 1 and R 4 Each polar group possessed by the carbon atom 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 containing 1 to 9 carbon atoms to which the polar groups are not bonded. 1 and R 4 The terminal polar group and the polar group adjacent to the terminal polar group can be oriented to be closely attached to the protective layer through the linking group containing the carbon atom to which the polar group is not bonded. 1 and R 4 The terminal groups shown are unlikely to float up and form lumps, and excellent floating stability is obtained.

[0127] In R 1 and R 4In the above, atoms other than carbon atoms may exist between carbon atoms to which adjacent polar groups are bonded. Examples of atoms other than carbon atoms include oxygen atoms and nitrogen atoms.

[0128] In addition, R 1 and R 4 For having been combined with R 2 The terminal group of the oxygen atom of the methylene group (-CH2-) is bonded. 1 and R 4 In combination with R 1 and R 4 Each adjacent CH2 has an oxygen atom at its end. 1 and R 4 The oxygen atom at the end of the fluorine-containing ether compound forms an ether bond (-O-) with the atoms bonded to both sides of the ether bond. The ether bond imparts moderate flexibility to the fluorine-containing ether compound represented by formula (1), making R 1 and R 4 The polar group contained in the terminal group has an increased affinity with the protective layer. Thus, the fluorine-containing ether compound represented by formula (1) can form a lubricating layer having excellent adhesion with the protective layer.

[0129] R 1 and R 4 The polar group is preferably selected from a hydroxyl group (-OH), an amino group (-NH2), a carboxyl group (-COOH), a formyl group (-(C=O)H), a carbonyl group (-CO-), a sulfone group (-SO3H), a cyano group (-CN), and a group having an amide bond (-NR 7 COR 8 or-CONR 9 R 10 ; R 7 , R 8 , R 9 and R 10 Each independently is a hydrogen atom or a polar group in an organic group. In the group having an amide bond, the above R 7 With R 8 can be combined with each other to form a ring, the above R 9 With R 10 The above R in the group having an amide bond may be bonded to each other to form a ring. 7 , R 8 , R 9 and R 10 Preferably, each is independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group. As the group having an amide bond, an acetamide group (-NHC(=O)CH3) or a formamide group (-C(=O)NH2) is preferred. 1 and R 4The two to four polar groups possessed by each may be partially or entirely the same or may be different from each other.

[0130] R 1 and R 4 Preferably, each independently contains at least one polar group selected from a hydroxyl group, a cyano group, and a group having an amide bond. 1 and R 4 More preferably, each contains at least one hydroxyl group as a polar group.

[0131] R 1 and R 4 The 2 to 4 polar groups possessed by each of the groups are preferably polar groups selected from a hydroxyl group, a cyano group, and a group having an amide bond.

[0132] In the fluorine-containing ether compound represented by formula (1), R 1 and R 4 Preferably, each independently is a terminal group represented by any one of formulae (3-1) to (3-4).

[0133]

[0134] (In formula (3-1), p represents an integer of 0 to 3, r represents an integer of 1 to 5, and the total value of p and r is 1 to 5; q represents an integer of 0 to 2; and A represents a polar group.)

[0135] (In formula (3-2), s represents an integer from 0 to 2, and t represents an integer from 1 to 5.)

[0136] (In formula (3-3), u represents an integer of 2 to 4; Y represents a linear alkylene group which may have an ether oxygen, or a single bond; when Y is the above alkylene group, the total number of carbon atoms and oxygen atoms possessed by Y is 1 to 5.)

[0137] (In formula (3-4), v represents an integer of 1 to 3; B represents a polar group in which a hydrogen atom at any position of the benzene ring is substituted.)

[0138] In R 1 and R 4 When it is a terminal group represented by any one of formulae (3-1) to (3-4), R in formula (1) 1 The polar group and R 4 The total number of polar groups (R 1 and / or R 4 is the number of hydroxyl groups and polar groups A in the case of formula (3-1), and R 1 and / or R 4 The number of hydroxyl groups in the case of formula (3-2) and formula (3-3) and R 1 and / or R 4In the case of formula (3-4), the total number of the hydroxyl groups and the polar groups B) is 4 to 8, preferably 4 to 6, more preferably 4 to 5, and most preferably 4.

[0139] The connecting group between the carbon atom to which the polar group A arranged at the terminal of the terminal group represented by formula (3-1) is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group A arranged at the terminal is bonded contains an oxygen atom forming an ether bond. In formula (3-1), p represents an integer of 0 to 3, r represents an integer of 1 to 5, and the total value of p and r is 1 to 5. Therefore, the connecting group has a linear structure consisting of 3 to 7 atoms including the polar group A and the carbon atom to which the hydroxyl group is not bonded.

[0140] In the terminal group shown in formula (3-1), since the above-mentioned linking group is a linear structure composed of more than 3 atoms including an oxygen atom forming an ether bond, a polar group A and a carbon atom to which a hydroxyl group is not bonded, the distance between the polar group A and the hydroxyl group adjacent to the polar group A is appropriate. Therefore, the interaction between the polar group A and the hydroxyl group adjacent to the polar group A in the molecule can be suppressed, and the polar group A and the hydroxyl group adjacent to the polar group A can be closely attached to the protective layer. In addition, since the above-mentioned linking group is a linear structure composed of more than 3 atoms, the mobility of the molecule is appropriate and intramolecular agglomeration is not easy to occur.

[0141] In addition, since the above-mentioned linking group is a straight-chain structure composed of 7 or less atoms including an oxygen atom forming an ether bond, a polar group A, and a carbon atom to which a hydroxyl group is not bonded, there is no situation where the hydrophobicity of the linking group is too high to hinder the adhesion with the protective layer.

[0142] Based on these facts, the lubricating layer containing the fluorinated ether compound whose linking group has a linear structure consisting of 3 to 7 atoms including the polar group A and the carbon atoms to which the hydroxyl group is not bonded has excellent adhesion with the protective layer, excellent floating stability, and a high adhesion suppressing effect.

[0143] In formula (3-1), the total value of p and r is 1 to 5, preferably 1 to 3. 1 and R 4 In the embodiment, the carbon atoms included in the linking group disposed between the carbon atoms bonded to the polar groups prevent the intramolecular interaction between the adjacent polar groups from occurring in priority to the interaction between the polar groups and the protective layer, so that R 1 and R 4 On the other hand, if the number of carbon atoms contained in the linking group is too large, sometimes R 1 and R 4The flexibility of the terminal group shown in formula (3-1) is reduced, and it is difficult to evenly coat the protective layer. In the terminal group shown in formula (3-1), since the total value of p and r is 5 or less, R 1 and R 4 The alkylene chain of the main chain portion is not too long. Therefore, it is possible to prevent the end portion from floating due to the decrease in flexibility of the end portion due to the long rigid alkylene chain and the weakened interaction with the protective layer. p is preferably 0 or 1, more preferably 0. r is preferably 1 or 2, more preferably 1.

[0144] A in formula (3-1) represents a polar group. A is preferably selected from a hydroxyl group (-OH), an amino group (-NH2), a carboxyl group (-COOH), a formyl group (-(C=O)H), a carbonyl group (-CO-), a sulfone group (-SO3H), a cyano group (-CN), and a group having an amide bond (-NR 7 COR 8 or-CONR 9 R 10 ; R 7 , R 8 , R 9 and R 10 Each independently is a hydrogen atom or a polar group in an organic group. As the group having an amide bond, there can be mentioned 1 and R 4 The group having an amide bond exemplified in the description of the polar group is particularly preferably an acetamide group (-NHC(=O)CH3) or a formamide group (-C(=O)NH2) because it is a fluorine-containing ether compound capable of forming a lubricating layer that interacts more strongly with the protective layer.

[0145] Among these polar groups, A is more preferably a polar group selected from a hydroxyl group, a cyano group, and a group having an amide bond, and is further preferably a hydroxyl group, an acetamide group, or a formamide group.

[0146] When A in formula (3-1) is a hydroxyl group, all polar groups in formula (3-1) are hydroxyl groups. 1 and R 4 If all the polar groups are hydroxyl groups, the coating state of the protective layer by the fluorinated ether compound becomes more uniform, and a lubricating layer with better adhesion can be formed. 1 and R 4 When one of them is of formula (3-1) and A is a hydroxyl group, R 1 and R 4 The other one of them is preferably any one of formula (3-1), formula (3-2) and formula (3-3) in which A is a hydroxyl group.

[0147] When A in the formula (3-1) is an acetamide group or a formamide group, it becomes a fluorine-containing ether compound capable of forming a lubricating layer that interacts more strongly with the protective layer.

[0148] In formula (3-1), q represents an integer of 0 to 2. The number of polar groups in formula (3-1) is q+2. As described above, R 1 and R 4 The number of polar groups contained is preferably 3 or less, and most preferably 2. Therefore, q in formula (3-1) is preferably 0 or 1, and more preferably 0.

[0149] In the terminal group shown in formula (3-2), the connecting group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded does not contain an oxygen atom. T in formula (3-2) represents an integer of 1 to 5. Therefore, the above-mentioned connecting group has a straight-chain structure consisting of 1 to 5 atoms including carbon atoms to which the hydroxyl group is not bonded. Since the above-mentioned connecting group contained in formula (3-2) is a straight-chain structure consisting of more than one atom including carbon atoms to which the hydroxyl group is not bonded, the distance between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group is appropriate. Therefore, the interaction between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group in the molecule can be suppressed, and intramolecular agglomeration is not easy to occur.

[0150] In addition, as mentioned above, in R 1 and R 4 In the case where the number of carbon atoms contained in the linking group disposed between the carbon atoms bonded to the polar group is too large, R 1 and R 4 The flexibility of the terminal group represented by formula (3-2) is reduced, and it is difficult to uniformly cover the entire surface of the protective layer. In the terminal group represented by formula (3-2), since t is 5 or less, R 1 and R 4 The alkylene chain of the main chain portion is not too long. Therefore, it is possible to prevent the flexibility of the terminal portion from decreasing due to the rigid alkylene chain being longer, and the interaction with the protective layer from being weakened, thereby preventing the terminal portion from floating up. t is preferably less than 4, more preferably 1 or 2, and further preferably 1.

[0151] Furthermore, since the linking group has a linear structure consisting of 5 or less atoms excluding oxygen atoms forming ether bonds and including carbon atoms to which hydroxyl groups are not bonded, the linking group does not have excessively high hydrophobicity to hinder adhesion to the protective layer.

[0152] Based on these circumstances, the lubricating layer containing the fluorinated ether compound whose connecting group has a linear structure consisting of 1 to 5 atoms containing no oxygen atoms forming ether bonds and containing unbonded carbon atoms of hydroxyl groups has excellent adhesion to the protective layer, obtains excellent floating stability, and has a high adhesion suppression effect.

[0153] In formula (3-2), s represents an integer of 0 to 2. The number of polar groups in formula (3-2) is s+2. As described above, R 1 and R 4 The number of polar groups contained is preferably 3 or less, and most preferably 2. Therefore, s in formula (3-2) is preferably 0 or 1, and more preferably 0.

[0154] The terminal group represented by formula (3-3) has no secondary hydroxyl group but has two primary hydroxyl groups. 1 and / or R 4 When the hydroxyl groups contained are primary hydroxyl groups, the hydroxyl groups are more likely to participate in the interaction with the active points on the protective layer than when they are secondary hydroxyl groups. The terminal group represented by formula (3-3) does not have secondary hydroxyl groups, but only has two primary hydroxyl groups that are more likely to interact with the active points on the protective layer. 1 and / or R 4 In the case of a terminal group represented by formula (3-3), it becomes a fluorine-containing ether compound capable of forming a lubricating layer having good adhesion to the protective layer.

[0155] In addition, in the terminal group represented by formula (3-3), the connecting group between the carbon atoms to which the two primary hydroxyl groups are respectively bonded contains the carbon atom to which the hydroxyl group is not bonded, and the oxygen atom forming the ether bond. u in formula (3-3) represents an integer of 2 to 4. Y represents a straight-chain alkylene group which may have an ether oxygen, or a single bond. When Y is the above-mentioned alkylene group, the total number of carbon atoms and oxygen atoms possessed by Y is 1 to 5. Therefore, the above-mentioned connecting group has a structure consisting of 3 to 10 atoms including the carbon atom to which the hydroxyl group is not bonded, and the oxygen atom forming the ether bond.

[0156] In the terminal group shown in formula (3-3), since the above-mentioned linking group is a structure composed of more than 3 atoms including an oxygen atom forming an ether bond and a carbon atom to which a hydroxyl group is not bonded, the distance between the two primary hydroxyl groups is appropriate. Therefore, the mobility of the molecule is appropriate and intramolecular agglomeration is not likely to occur. Therefore, it becomes a fluorine-containing ether compound that can form a lubricating layer with good adhesion to the protective layer.

[0157] In addition, in the terminal group represented by formula (3-3), since the above-mentioned connecting group is a structure composed of 10 atoms or less including oxygen atoms forming ether bonds and carbon atoms to which hydroxyl groups are not bonded, there is no situation where the hydrophobicity of the connecting group is too high to hinder the adhesion with the protective layer.

[0158] Therefore, the lubricating layer containing the serflurane compound whose linking group has a structure consisting of 3 to 10 atoms including an oxygen atom forming an ether bond and a carbon atom to which a hydroxyl group is not bonded has excellent adhesion to the protective layer, excellent floating stability, and a high adhesion suppression effect.

[0159] In addition, since u in formula (3-3) is 2 or more, -O-(CH2) in formula (3-3) u The primary hydroxyl group contained in -OH (hereinafter sometimes referred to as "side chain part") and the R 1 and R 4 Combined R 2 The distance between the PFPE chain shown and the bulky parts such as tertiary carbon to which the side chain part of formula (3-3) is bonded is sufficiently far. Therefore, the primary hydroxyl group contained in the side chain part of formula (3-3) can move freely and easily. In addition, since u is 4 or less, the flexibility of the side chain part in formula (3-3) is maintained. Therefore, it becomes a fluorine-containing ether compound that can form a lubricating layer with excellent adhesion to the protective layer, high floating stability, and high adhesion suppression effect.

[0160] In addition, as mentioned above, in R 1 and R 4 In the case where the number of carbon atoms contained in the linking group disposed between the carbon atoms bonded to the polar group is too large, R 1 and R 4 The flexibility of the terminal group is reduced, and it is difficult to uniformly cover the entire surface of the protective layer. Therefore, u is preferably 2 or 3, and more preferably 2.

[0161] In addition, in formula (3-3), the primary hydroxyl group contained in -Y-CH2-OH is bonded to the carbon atom to which the side chain portion of formula (3-3) is bonded via -Y-CH2-. Therefore, compared with the case where the hydroxyl group is directly bonded to the above-mentioned carbon atom, the primary hydroxyl group contained in -Y-CH2-OH is easy to move freely and is easy to participate in the interaction with the active point on the protective layer.

[0162] Since the primary hydroxyl group contained in -Y-CH2-OH in formula (3-3) is more likely to participate in the interaction with the active point on the protective layer, Y in formula (3-3) is preferably not a single bond but a straight-chain alkylene group that may have an ether oxygen. The reason is that in this case, the primary hydroxyl group contained in -Y-CH2-OH and the alkylene group connected to R via the methylene group are not a single bond. 1 and R 4 Combined R 2 The distance between bulky sites such as the tertiary carbon to which the side chain portion of the PFPE chain shown in the formula (3-3) is bonded becomes greater, and the primary hydroxyl group contained in -Y-CH2-OH can move more freely.

[0163] In formula (3-3), when Y is a straight-chain alkylene group that may have ether oxygen, the total number of carbon atoms and oxygen atoms possessed by Y is 1 to 5. In the terminal group represented by formula (3-3), since the total number of carbon atoms and oxygen atoms possessed by Y is 5 or less, the alkylene chain of the main chain portion in formula (3-3) will not be too long. Therefore, it is possible to prevent the flexibility of the terminal portion from decreasing due to the longer rigid alkylene chain, and the terminal portion from floating due to the weakened interaction with the protective layer. The total number of carbon atoms and oxygen atoms possessed by Y is preferably 1 to 4, and more preferably 1 to 3. The number of carbon atoms possessed by Y is preferably 1 to 3, and more preferably 1 to 2.

[0164] In the formula (3-3), when Y is a straight-chain alkylene group which may have an ether oxygen, specific examples include -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2OCH2-, -CH2OCH2CH2-, -CH2OCH2CH2CH2-, -CH2CH2OCH2-, and the like.

[0165] In the terminal group represented by formula (3-4), the linking group between the carbon atom to which the polar group B is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group B is bonded contains an oxygen atom forming an ether bond. The above-mentioned linking group has a structure consisting of 3 to 5 atoms including the polar group B and the carbon atom to which the hydroxyl group is not bonded. The number of atoms of the above-mentioned linking group refers to the number of atoms of the shortest distance between the carbon atom to which the polar group B is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group B is bonded.

[0166] In the terminal group shown in formula (3-4), since the above-mentioned linking group is a structure composed of more than 3 atoms including an oxygen atom forming an ether bond, a polar group B and a carbon atom to which a hydroxyl group is not bonded, the distance between the polar group B and the hydroxyl group adjacent to the polar group B is appropriate. In addition, since the benzene ring is rigid, it is difficult to rotate freely. Therefore, the interaction between the polar group B substituted on the benzene ring and the hydroxyl group adjacent to the polar group B can be suppressed.

[0167] In addition, when v in formula (3-4) is 2 or more, -(CH2CH(OH)CH2O) v - The linking group between the carbon atoms to which the adjacent plurality of hydroxyl groups are bonded has a linear structure consisting of three atoms including an oxygen atom forming an ether bond, a polar group B, and a carbon atom to which the hydroxyl group is not bonded. Since the linking group is a linear structure consisting of three atoms including a polar group B and a carbon atom to which the hydroxyl group is not bonded, the distance between adjacent hydroxyl groups is appropriate. Therefore, the interaction between the hydroxyl groups in the molecule can be suppressed.

[0168] According to these conditions, the fluorinated ether compound having the terminal group shown in formula (3-4) can inhibit the interaction between polar groups in the molecule. Therefore, the lubricating layer containing the fluorinated ether compound having the terminal group shown in formula (3-4) has excellent adhesion to the protective layer, obtains excellent floating stability, and has a high adhesion inhibition effect.

[0169] B in formula (3-4) represents a polar group substituted at any position of the benzene ring. B is preferably selected from a hydroxyl group (-OH), an amino group (-NH2), a carboxyl group (-COOH), a formyl group (-(C=O)H), a carbonyl group (-CO-), a sulfone group (-SO3H), a cyano group (-CN), and a group having an amide bond (-NR 7 COR 8 or-CONR 9 R 10 ; R 7 , R 8 , R 9 and R 10 Each independently is a hydrogen atom or a polar group in an organic group. As the group having an amide bond, there can be mentioned 1 and R 4 The group having an amide bond exemplified in the description of the polar group is particularly preferably an acetamide group (-NHC(=O)CH3) or a formamide group (-C(==O)NH2) because it is a fluorine-containing ether compound capable of forming a lubricating layer that interacts more strongly with the protective layer.

[0170] Among these polar groups, B is more preferably a polar group selected from a cyano group and a group having an amide bond, and is further preferably a cyano group, an acetamide group or a formamide group.

[0171] In formula (3-4), v represents an integer of 1 to 3. The number of polar groups in formula (3-4) is v+1. As described above, R 1 and R 4 The number of polar groups contained is preferably 3 or less, and most preferably 2. Therefore, v in formula (3-4) is preferably 1 or 2, and more preferably 1.

[0172] R 1 With R 4 They can be the same or different. If R 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.

[0173] (R 2 PFPE chain shown)

[0174] In the fluorine-containing ether compound represented by formula (1), R 4When a lubricant containing 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.

[0175] (x+1) 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 more 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 .

[0176] 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 perfluoromethylene oxide, perfluoroethylene oxide, perfluoropropylene oxide, perfluoroisopropylene oxide, and perfluorobutylene oxide.

[0177] The (x+1) R in formula (1) 2 Preferably, each independently is a PFPE chain represented by the following formula (4) derived from, for example, a polymer or copolymer of a perfluoroalkylene oxide.

[0178] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0179] (In formula (4), 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 (4).)

[0180] In formula (4), 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. It may be 1 to 8, 2 to 6, 3 to 5, or the like.

[0181] In formula (4), 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 (4), w1 and w6 are determined by the structure of the repeating unit arranged at the end of the chain structure, etc.

[0182] In formula (4), (CF2O), (CF2CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) are repeating units. There is no particular restriction on the arrangement order of the repeating units in formula (4). In addition, there is no particular restriction on the number of types of repeating units in formula (4).

[0183] 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 (4-1) to (4-4).

[0184] If (x+1) R 2 Each of the (x+1) R 2 When each is any one of the PFPE chains shown in formulas (4-1) to (4-4), the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) in the PFPE chain to the number of carbon atoms is appropriate. Therefore, a fluorinated ether compound having a moderate hardness is obtained. Therefore, the fluorinated ether compound applied on the protective layer is not easy to agglomerate on the protective layer, and a 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 floating stability can be formed.

[0185] -CF2-(OCF2CF2) h -(OCF2) i -OCF2- (4-1)

[0186] (In formula (4-1), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0187] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2- (4-2)

[0188] (In formula (4-2), j represents the average degree of polymerization and is 1 to 15.)

[0189] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2- (4-3)

[0190] (In formula (4-3), k represents the average degree of polymerization and is 1 to 10.)

[0191] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 - (4-4)

[0192] (In formula (4-4), w8 and w9 represent the average degree of polymerization, and each independently represents 1 to 20; w7 and w10 represent the average value of the number of CF2, and each independently represents 1 to 2.)

[0193] In formula (4-1), there is no particular restriction on the arrangement order of (OCF2CF2) and (OCF2) as repeating units. In formula (4-1), the number h of (OCF2CF2) and the number i of (OCF2) may be the same or different. The PFPE chain shown in formula (4-1) may be a polymer of (OCF2CF2). In addition, the PFPE chain shown in formula (4-1) may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF2CF2) and (OCF2).

[0194] In formulas (4-1) to (4-3), since h, which represents the average degree of polymerization, is 1 to 20, i is 0 to 20, j is 1 to 15, and k is 1 to 10, a fluorine-containing ether compound is obtained that can obtain a lubricating layer having good lubricity. In addition, in formulas (4-1) to (4-3), since h and i, which represent the average degree of polymerization, are 20 or less, j is 15 or less, and k 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, which is preferred. In order to obtain a fluorine-containing ether compound that is easy to wet and spread on the protective layer and easy to obtain a lubricating layer with a uniform film thickness, h, i, j, and k, which represent the average degree of polymerization, are preferably 1 to 10, more preferably 1.5 to 8, and further preferably 2 to 7.

[0195] In formula (4-4), there is no particular restriction on the arrangement order of (CF2CF2CF2O) and (CF2CF2O) as repeating units. In formula (4-4), the number w8 of (CF2CF2CF2O) representing the average degree of polymerization and the number w9 of (CF2CF2O) may be the same or different. Formula (4-4) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF2CF2CF2O) and (CF2CF2O).

[0196] In formula (4-4), w8 and w9 representing the average degree of polymerization are each independently 1-20, preferably 1-15, and more preferably 1-10.

[0197] w7 and w10 in formula (4-4) are average values ​​of the number of CF2, and each independently represents 1 to 2. w7 and w10 are determined by the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (4-4).

[0198] In the fluorine-containing ether compound represented by formula (1), it is preferred that the (x+1) R in formula (1) 2 Same, x R 3 Same, R 1 With R 4 This is because it is a fluorine-containing ether compound that can be easily and efficiently produced.

[0199] Specifically, the fluorine-containing ether compound represented by the formula (1) is preferably any one of the compounds represented by the following formulae (AA) to (AV) and (BA) to (BK).

[0200] When the compound represented by formula (1) is any of the compounds represented by the following formulae (AA) to (AV) and (BA) to (BK), the raw materials are easily available and a lubricating layer having better floating stability and a high adhesion suppression effect on the magnetic recording medium can be formed even if the thickness is thin.

[0201] In the compounds represented by the following formulas (AA) to (AV), (BA) to (BK), Rf1, Rf2, and Rf3 representing the PFPE chain each have the following structure. That is, in the compounds represented by the following formulas (AA) to (AP), (AS) to (AV), (BA) to (BI), and (BK), Rf1 is the PFPE chain represented by the above formula (4-1). In the compounds represented by the following formulas (AQ) and (BJ), Rf2 is the PFPE chain represented by the above formula (4-2). In the compound represented by the following formula (AR), Rf3 is the PFPE chain represented by the above formula (4-3). In addition, h and i in Rf1 representing the PFPE chain in the formulas (AA) to (AV), (BA) to (BK), j in Rf2, and k in Rf3 are not necessarily integers because they are values ​​representing the average degree of polymerization.

[0202]

[0203] In the compounds represented by the following formulae (AA) to (AV) and (BA) to (BK), at least one R 3 It is a linking group represented by the above formula (2-1) or (2-2).

[0204] In the compounds represented by the following formulae (AA) to (AV) and (BA) to (BK), R 1 and R 4 Each is a terminal group represented by any one of the above formulae (3-1) to (3-4).

[0205] The compounds represented by the following formulae (AA) to (AV) and (BA) to (BK) all have (x+1) R in formula (1): 2 same.

[0206] In the compounds represented by the following formulae (AA) to (AM), x in the formula (1) is 1. 1 and R 4 is the terminal group represented by the above formula (3-1) or (3-2). 3 is a linking group represented by the above formula (2-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0207] In the compounds represented by the following formulae (AN) to (AP), x in the formula (1) is 1. 1 and R 4 is the terminal group represented by the above formula (3-1). 3 is a linking group represented by the above formula (2-2). 2 It is the PFPE chain represented by the above formula (4-1).

[0208] In the compounds represented by the following formulas (AQ) and (AR), x in the formula (1) is 1. 1 and R 4 is the terminal group represented by the above formula (3-1). 3 is a linker represented by the above formula (2-1). 2 is the PFPE chain represented by the above formula (4-2). 2 It is the PFPE chain represented by the above formula (4-3).

[0209] In the compounds represented by the following formulas (AS) and (AT), x in the formula (1) is 1. 1 and R 4 is the terminal group represented by the above formula (3-3). 3 is a linking group represented by the above formula (2-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0210] In the compounds represented by the following formulas (AU) and (AV), x in the formula (1) is 1. 1 and R 4 is the terminal group represented by the above formula (3-4). 3 is a linking group represented by the above formula (2-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0211] In the compounds represented by the following formulae (BA) to (BF), x in the formula (1) is 2. 1 and R 4 is the terminal group represented by the above formula (3-1) or (3-2). 3 is a linking group represented by the above formula (2-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0212] In the compounds represented by the following formulas (BG) and (BH), x in the formula (1) is 2. 1 and R 4 is the terminal group represented by the above formula (3-1). 3 is a linking group represented by the above formula (2-2). 2 It is the PFPE chain represented by the above formula (4-1).

[0213] In the compound represented by the following formula (BI), x in the formula (1) is 2. 1 and R 4 is the terminal group represented by the above formula (3-1). 3One of them is a linking group represented by the above formula (2-1), and the other is a glycerol structure (-O-CH2-CH(OH)-CH2-O-). 2 It is the PFPE chain represented by the above formula (4-1).

[0214] In the compound represented by the following formula (BJ), x in the formula (1) is 2. 1 and R 4 is the terminal group represented by the above formula (3-1). 3 is a linking group represented by the above formula (2-1). 2 It is the PFPE chain represented by the above formula (4-2).

[0215] In the compound represented by the following formula (BK), x in the formula (1) is 2. 1 and R 4 is the terminal group represented by the above formula (3-1). 3 is a linking group represented by the above formula (2-2). 2 It is the PFPE chain represented by the above formula (4-1).

[0216]

[0217] (In the two Rf1 in formula (AA), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0218] (In the two Rf1 in formula (AB), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0219] (In the two Rf1 in formula (AC), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0220] (In the two Rf1 in formula (AD), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0221]

[0222] (In the two Rf1 in formula (AE), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0223] (In the two Rf1 in formula (AF), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0224] (In the two Rf1 in formula (AG), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0225]

[0226] (In the two Rf1 in formula (AH), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0227] (In the two Rf1 in formula (AI), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0228] (In the two Rf1 in formula (AJ), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0229]

[0230] (In the two Rf1 in formula (AK), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0231] (In the two Rf1 in formula (AL), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0232] (In the two Rf1 in formula (AM), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0233]

[0234] (In the two Rf1 in formula (AN), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0235] (In the two Rf1 in formula (AO), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0236] (In the two Rf1 in formula (AP), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0237]

[0238] (In the two Rf2 in formula (AQ), j represents the average degree of polymerization, which is 1 to 15; in the two Rf2, the average degree of polymerization may be the same or different.)

[0239] (In the two Rf3 in formula (AR), k represents the average degree of polymerization, which is 1 to 10; in the two Rf3, the average degree of polymerization may be the same or different.)

[0240] (In the two Rf1 in formula (AS), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0241] (In the two Rf1 in formula (AT), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0242]

[0243] (In the two Rf1 in formula (AU), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0244] (In the two Rf1 in formula (AV), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average polymerization degrees may be the same or different.)

[0245]

[0246] (In the three Rf1 in formula (BA), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0247] (In the three Rf1 in formula (BB), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0248] (In the three Rf1 in formula (BC), h and i represent the average degree of polymerization, h represents 1-20, and i represents 0-20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0249]

[0250] (In the three Rf1 in formula (BD), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0251] (In the three Rf1 in formula (BE), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0252] (In the three Rf1 in formula (BF), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0253]

[0254] (In the three Rf1 in formula (BG), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0255] (In the three Rf1 in formula (BH), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0256] (In the three Rf1 in formula (BI), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0257] (In the three Rf2 in formula (BJ), j represents the average degree of polymerization and is 1 to 15; j in the three Rf2 may be different from each other, or may be partially or entirely the same.)

[0258] (In the three Rf1 in formula (BK), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.)

[0259] 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 1,000 to 5,000. It may be 2,000 to 4,500, 2,500 to 4,000, 3,000 to 3,500, etc. 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 1,000 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 applied to a lubricant, the number average molecular weight of the fluorinated ether compound is preferably 5,000 or less.

[0260] The number average molecular weight (Mn) of the fluorinated ether compound was determined by using AVANCE III 400 manufactured by Bruker Biospin Co., Ltd. 1 H-NMR and 19 Specifically, the value measured by F-NMR. 19 The number of repeating units of the PFPE chain was calculated from the integrated value measured by F-NMR, and the number average molecular weight was determined. 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.

[0261] 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.

[0262] 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.

[0263] [Manufacturing method]

[0264] 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.

[0265] [First manufacturing method (when x is 1)]

[0266] (R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Same, 2 R 2 Same situation)

[0267] Prepare R in formula (1) 2 The corresponding perfluoropolyether chain has fluorine compounds having hydroxymethyl groups (-CH2OH) at both ends.

[0268] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the fluorine-based compound is fused with a hydroxyl group having the same structure as R in formula (1). 1 The corresponding group (with =R 4 Thus, the epoxy compound corresponding to R is obtained. 2 One end of the corresponding perfluoropolyether chain has 1 The corresponding group (with =R 4 The intermediate compound 1-1 of the corresponding group).

[0269] As R in formula (1) 1 The corresponding group (with =R 4 The epoxy compound of the corresponding group) can be, for example, the compounds represented by the following formulae (5-1) to (5-14). THP in the following formulae (5-1) to (5-10) represents a tetrahydropyranyl group.

[0270]

[0271] It has the same R as in formula (1) 1 The corresponding group (with =R 4 The epoxy compound of the corresponding group) can be produced, for example, by the method shown below. That is, as shown in the following formula (6-1), a group having the same R as in formula (1) can be used. 1 (or R 4 ) is produced by a method of reacting an alcohol having a structure (R in formula (6-1)) corresponding to a part of the terminal group shown in ), with a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (formula (6-1) is the case where the halogen compound is a bromine compound). The number of methylene groups contained in the halogen compound having an epoxy group (a1 in formula (6-1)) is 1 to 4 and can be appropriately determined according to the structure of the terminal group of the compound to be synthesized.

[0272]

[0273] (In formula (6-1), R represents the same as R in formula (1) 1 (or R 4 ) represents a structure corresponding to a part of the terminal group shown in the formula; a1 represents an integer of 1 to 4.

[0274] In addition, the above-mentioned epoxy compound can be produced by the method shown below. That is, as shown in the following formula (6-2), a compound having the same R as in formula (1) can be prepared. 1 (or R 4 ) is reacted with an alcohol having a structure (R in formula (6-2)) corresponding to a part of the terminal group shown in the formula, and a halogen compound such as a bromine compound or a chlorine compound having an alkenyl group (the formula (6-2) is the case where the halogen compound is a bromine compound). Then, it is manufactured by a method of oxidizing the obtained compound by allowing meta-chloroperbenzoic acid (mCPBA) to act. The number of methylene groups contained in the halogen compound having an alkenyl group (a2 in formula (6-2)) is 1 to 4, which can be appropriately determined according to the structure of the terminal group of the compound to be synthesized.

[0275]

[0276] (In formula (6-2), R represents the same as R in formula (1) 1 (or R 4 ) represents a structure corresponding to a part of the terminal group shown in the formula; a2 represents an integer from 1 to 4.

[0277] In addition, the above-mentioned epoxy compound can be produced by the method shown below. That is, as shown in the following formula (6-3), a 1 (or R 4 ) is reacted with an alcohol having a structure (R in formula (6-3)) corresponding to a part of the terminal group shown in ), and a compound having an alkenyl group and an epoxy group. Then, the compound obtained by the addition reaction is oxidized by allowing meta-chloroperbenzoic acid (mCPBA) to act. Before the compound obtained by the addition reaction is oxidized by allowing meta-chloroperbenzoic acid (mCPBA) to act, the hydroxyl group generated by the addition reaction can be protected by a known method. The number of methylene groups contained in the compound having an alkenyl group and an epoxy group (a3 in formula (6-3)) is 1 to 4, which can be appropriately determined according to the structure of the terminal group of the compound to be synthesized.

[0278]

[0279] (In formula (6-3), R represents the same as R in formula (1) 1 (or R 4) represents a structure corresponding to a part of the terminal group shown in the formula; a3 represents an integer of 1 to 4.

[0280] Then, the hydroxyl group at one end of the intermediate compound 1-1 produced in the first reaction is reacted with a hydroxyl group having two residues corresponding to R in the formula (1). 3 The corresponding epoxy compound is reacted (second reaction).

[0281] As a having two R 3 As the corresponding epoxy group compound, for example, compounds represented by the following formulae (7-1) to (7-3) can be used. THP in the following formula (7-3) represents a tetrahydropyranyl group.

[0282]

[0283] When using the compound represented by formula (7-2) as a compound having two R 3 In the case of a compound having a corresponding epoxy group, for example, it can be produced by the method shown below. That is, it can be produced by a method in which the alkenyl group of a compound having an alkenyl group and an epoxy group (allyl glycidyl ether) is oxidized by reacting m-chloroperbenzoic acid (mCPBA) as shown in the following formula (8-1).

[0284]

[0285] When the compound represented by formula (7-3) is used as the above-mentioned epoxy compound, for example, it can be manufactured using the method shown below. That is, as shown in the following formula (8-2), a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (the formula (8-2) is the case where the halogen compound is a bromine compound) and an alcohol (allyl alcohol) having an alkenyl group can be reacted. Furthermore, the secondary hydroxyl group of the compound generated after the reaction is protected with dihydropyran, and meta-chloroperbenzoic acid (mCPBA) is allowed to act to oxidize the alkenyl group. THP in formula (8-2) represents tetrahydropyranyl.

[0286]

[0287] The compound represented by formula (7-3) can be manufactured, for example, using the method shown below. That is, it can be manufactured by reacting a compound having two hydroxyl groups with a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (the halogen compound in formula (8-3) is a bromine compound). THP in formula (8-3) represents tetrahydropyranyl.

[0288]

[0289] As a having two R 3 As the corresponding epoxy group-containing compound, a commercially available product can be used.

[0290] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 1 and R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Same, 2 R 2 Same compound.

[0291] [Second manufacturing method (when x is 1)]

[0292] (R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Same, 2 R 2 Same situation)

[0293] Prepare R in formula (1) 2 The corresponding perfluoropolyether chain has fluoro compounds with hydroxymethyl groups at both ends. Next, the hydroxyl group of the hydroxymethyl group at one end of the fluoro compound is reacted with an epoxy compound having a structure corresponding to the chain portion (main chain portion) containing Y of the terminal group shown in formula (3-3) (first reaction). Thus, a fluoropolymer having a structure corresponding to R 2 The corresponding intermediate compound 1-2 has a group corresponding to the chain portion (main chain portion) containing Y of the terminal group represented by formula (3-3) at one end of the perfluoropolyether chain and a secondary hydroxyl group forming the side chain portion of the terminal group represented by formula (3-3).

[0294] As a terminal group represented by formula (3-3) (with =R 1 and R 4 As the epoxy compound having a structure corresponding to the chain portion (main chain portion) containing Y, for example, the compounds represented by the above formulae (5-1) to (5-4) and (5-9), the compound represented by the later-described formula (17), etc. can be used.

[0295] Next, the hydroxyl group at one end of the intermediate compound 1-2 is fused to a compound having the same structure as R in the formula (1). 3 The corresponding leaving group reacts with the protected hydroxyl compound to obtain the intermediate compound 1-3 (second reaction).

[0296] As with R 3The corresponding leaving group and the compound of the protected hydroxyl group include, for example, the compound represented by the formula (14) described below, the compound represented by the formula (31) below, and the compound represented by the formula (32) below. In the formulas (31) and (32), THP represents tetrahydropyranyl, and Ts represents toluenesulfonyl (p-toluenesulfonyl).

[0297]

[0298] Next, the side chain portion having the terminal group represented by formula (3-3) is made to have -(CH2) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 1-3 (third reaction).

[0299] As the side chain part having the terminal group represented by formula (3-3), -(CH2) u Examples of the halogen compound of a protected hydroxyl group corresponding to -OH include the compound represented by the formula (16) described below, the compound represented by the formula (33) below, and the compound represented by the formula (34) below. THP in the formulas (33) and (34) represents tetrahydropyranyl.

[0300]

[0301] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 1 and R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Same, 2 R 2 Same compound.

[0302] [Third manufacturing method (when x is 1)]

[0303] (R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Different, and / or 2 R 2 Different situations)

[0304] First, make the 1 Side R 2 The corresponding perfluoropolyether chain has a hydroxyl group at one end of the fluorine-based compound having a hydroxymethyl group at both ends, and a 1 The corresponding group of epoxy compounds is reacted to obtain the intermediate compound 1a (first reaction).

[0305] Next, make the 4 Side R 2 The corresponding perfluoropolyether chain has a hydroxyl group at one end of the fluorine-based compound having a hydroxymethyl group at both ends, and a 4 The corresponding group is reacted with an epoxide to obtain an intermediate compound 1b (second reaction).

[0306] Next, the hydroxyl group at one end of the intermediate compound 1a is fused with a compound having the same R as in formula (1). 3 After the corresponding epoxy and alkenyl compounds are reacted, the double bond of the purified compound is oxidized to obtain an intermediate compound 1-4 (third reaction).

[0307] As R in formula (1) 3 As the corresponding compounds of epoxy group and alkenyl group, for example, compounds represented by formulae (9-1) to (9-3) described later can be used.

[0308] Next, the hydroxyl group at one terminal of the intermediate compound 1b is reacted with the epoxy group of the intermediate compound 1-4 obtained in the third reaction (fourth reaction).

[0309] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 1 and R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Different and / or 2 R 2 Different compounds.

[0310] [Fourth manufacturing method (when x is 1)]

[0311] (R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Different situations)

[0312] First, make the 1 Side R 2 The corresponding perfluoropolyether chain has a hydroxyl group at one end of the fluorine-based compound having a hydroxymethyl group at both ends, and a 1 The epoxy compound having a structure corresponding to the chain portion (main chain portion) containing Y at the terminal group represented by formula (3-3) is reacted to obtain an intermediate compound 1-2a (first reaction).

[0313] Next, make the 4 Side R2 The corresponding perfluoropolyether chain has a hydroxyl group at one end of the fluorine-based compound having a hydroxymethyl group at both ends, and a 4 The epoxy compound having a structure corresponding to the chain portion (main chain portion) containing Y at the terminal group represented by formula (3-3) is reacted to obtain an intermediate compound 1-2b (second reaction).

[0314] Next, the hydroxyl group at one end of the intermediate compound 1-2a is fused to a compound having the same structure as R in formula (1). 3 The corresponding leaving group reacts with a leaving group of the compound having a protected hydroxyl group to obtain an intermediate compound 1-3a (third reaction).

[0315] Next, the hydroxyl group at one end of the intermediate compound 1-2b is reacted with the leaving group of the intermediate compound 1-3a obtained in the third reaction to obtain the intermediate compound 1-3b (fourth reaction).

[0316] Next, make R 1 -(CH2) in the side chain portion of the terminal group represented by formula (3-3) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 1-3b to obtain the intermediate compound 1-5 (fifth reaction).

[0317] Next, make R 4 -(CH2) in the side chain portion of the terminal group represented by formula (3-3) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 1-5 (sixth reaction).

[0318] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 1 and R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Different compounds.

[0319] [Fifth manufacturing method (when x is 1)]

[0320] (R 1 is the terminal group shown in formula (3-3), R 4 In the case of a terminal group represented by formula (3-1), (3-2) or (3-4)

[0321] First, the intermediate compound 1-3a is obtained in the same manner as in the fourth production method (first reaction).

[0322] Next, the intermediate compound 1b is obtained in the same manner as in the third production method (second reaction).

[0323] Next, the hydroxyl group at one end of the intermediate compound 1b is reacted with the leaving group of the intermediate compound 1-3a obtained in the first reaction to obtain the intermediate compound 1-6 (third reaction).

[0324] Next, make R 1 -(CH2) in the side chain portion of the terminal group represented by formula (3-3) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 1-6 (fourth reaction).

[0325] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 1 and R 1 is the terminal group shown in formula (3-3), R 4 A compound having a terminal group represented by formula (3-1), (3-2) or (3-4).

[0326] [Sixth Manufacturing Method (When x is 2)]

[0327] (R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Same, and 2 R 3 Same, R 1 Side R 2 With R 4 Side R 2 Same situation)

[0328] First, the same operation as the first manufacturing method is performed to manufacture a 1 Side and R 4 Side R 2 One end of the corresponding perfluoropolyether chain has 1 The corresponding group (with =R 4 The intermediate compound 1-1 (the first reaction) is obtained by preparing the intermediate compound 1-1 of the corresponding group.

[0329] Next, prepare R at the center of the molecule in formula (1) 2The corresponding perfluoropolyether chain has hydroxymethyl (-CH2OH) groups at both ends of the fluorine-based compound. Next, the hydroxyl groups of the hydroxymethyl groups at both ends of the fluorine-based compound are connected to a fluorine-based compound having the same R as in formula (1). 3 The corresponding epoxy and alkenyl compounds are reacted (second reaction).

[0330] As R in formula (1) 3 As the corresponding compounds of epoxy group and alkenyl group, for example, compounds represented by the following formulae (9-1) to (9-3) can be used. THP in the following formula (9-3) represents tetrahydropyranyl.

[0331]

[0332] When the compound represented by formula (9-3) is used as the above-mentioned epoxy compound, for example, it can be manufactured by the method shown below. That is, as shown in the following formula (10-1), a halogen compound such as a bromine compound or a chlorine compound having an epoxy group (the formula (10-1) is the case where the halogen compound is a bromine compound) and an alcohol (allyl alcohol) having an alkenyl group can be reacted. Furthermore, it is manufactured by a method in which the secondary hydroxyl group of the compound generated after the reaction is protected with dihydropyran, and then meta-chloroperbenzoic acid (mCPBA) is allowed to act to oxidize only one alkenyl group. THP in the following formula (10-1) represents tetrahydropyranyl.

[0333]

[0334] The compound represented by formula (9-3) can be manufactured, for example, using the method shown below. That is, as shown in the following formula (10-2), a compound having two hydroxyl groups is reacted with a halogen compound such as a bromine compound or a chlorine compound having an alkenyl group (the halogen compound in formula (10-2) is a bromine compound), and after a substituent having an alkenyl group is introduced into one hydroxyl group, a halogen compound such as a bromine compound or a chlorine compound having an epoxy group is reacted (the halogen compound in formula (10-2) is a bromine compound) to manufacture. THP in the following formula (10-2) represents tetrahydropyranyl.

[0335]

[0336] Next, m-chloroperbenzoic acid (mCPBA) is allowed to act on the compound generated after the second reaction to oxidize the olefinic group (third reaction). 2 The two ends of the corresponding perfluoropolyether chain have the same two R 3The corresponding epoxy intermediate compound 2-1. The third reaction can be carried out after appropriately protecting the hydroxyl group of the compound produced after the second reaction by a known method.

[0337] Then, the hydroxyl group of the hydroxymethyl group disposed at one terminal of the intermediate compound 1-1 is reacted with the epoxy groups disposed at both terminals of the intermediate compound 2-1 (fourth reaction).

[0338] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 2 and R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Same, and 2 R 3 Same, R 1 Side R 2 With R 4 Side R 2 Same compound.

[0339] [Seventh Manufacturing Method (When x is 2)]

[0340] (R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Same, 2 R 3 Same, R 1 Side R 2 With R 4 Side R 2 Same situation)

[0341] First, the same method as the second manufacturing method is used to manufacture a 1 Side and R 4 Side R 2 One end of the corresponding perfluoropolyether chain has an intermediate compound 1-2 (first reaction) having a group corresponding to the chain portion (main chain portion) containing Y of the terminal group represented by formula (3-3) and a secondary hydroxyl group forming the side chain portion of the terminal group represented by formula (3-3).

[0342] Next, prepare R at the center of the molecule in formula (1) 2 The corresponding perfluoropolyether chain has hydroxymethyl (-CH2OH) groups at both ends of the fluorine-based compound. Next, the hydroxyl groups of the hydroxymethyl groups at both ends of the fluorine-based compound are connected to a fluorine-based compound having the same R as in formula (1). 3 The corresponding leaving group reacts with the protected hydroxyl compound (second reaction). Thus, R2 The two ends of the corresponding perfluoropolyether chain have the same two R 3 The corresponding structure and leaving group of the intermediate compound 2-2.

[0343] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1-2 is reacted with the intermediate compound 2-2 to obtain the intermediate compound 2-3 (third reaction).

[0344] Next, the side chain portion having the terminal group represented by formula (3-3) is made to have -(CH2) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 2-3 (fourth reaction).

[0345] After the above steps, a deprotection reaction is carried out using a known method, thereby preparing a compound wherein x in the formula (1) is 2, ' and R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Same, 2 R 3 Same, R 1 Side R 2 With R 4 Side R 2 Same compound.

[0346] [Eighth Manufacturing Method (When x is 2)]

[0347] (2 R 3 Same, R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Different situations, and / or R 1 Side R 2 With R 4 Side R 2 Different situations)

[0348] First, the same method as the third manufacturing method is used to manufacture a 1 Side R 2 One end of the corresponding perfluoropolyether chain has 1 In addition, the intermediate compound 1a corresponding to the group of R is prepared in the same manner as the third production method. 4 Side R 2 One end of the corresponding perfluoropolyether chain has 4The corresponding radical is the intermediate compound 1b (second reaction).

[0349] Next, in the same manner as the sixth production method, a compound R 2 The two ends of the corresponding perfluoropolyether chain have the same two R 3 The corresponding epoxy intermediate compound 2-1 (third reaction).

[0350] Then, the hydroxyl group of the hydroxymethyl group disposed at one terminal of the intermediate compound 1a is reacted with the epoxy group disposed at one terminal of the intermediate compound 2-1 to obtain the intermediate compound 2-4 (fourth reaction).

[0351] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1b is reacted with the epoxy group of the intermediate compound 2-4 obtained in the fourth reaction (fifth reaction).

[0352] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 2 and two R 3 Same, R 1 and R 4 is a terminal group represented by formula (3-1), (3-2) or (3-4), R 1 With R 4 Different situations, and / or R 1 Side R 2 With R 4 Side R 2 Different compounds.

[0353] [Ninth Manufacturing Method (When x is 2)]

[0354] (R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Different situations)

[0355] First, the same method as in the fourth manufacturing method is used to manufacture a 1 Side R 2 One end of the corresponding perfluoropolyether chain has 1 An intermediate compound 1-2a (first reaction) having a structure corresponding to the chain portion (main chain portion) containing Y at the terminal group represented by formula (3-3) is obtained.

[0356] In addition, the same operation as the fourth manufacturing method is performed to manufacture a 4 Side R 2 One end of the corresponding perfluoropolyether chain has4 An intermediate compound 1-2b (second reaction) having a structure corresponding to the chain portion (main chain portion) containing Y at the terminal group represented by formula (3-3) is obtained.

[0357] Next, the same operation as in the seventh production method is performed to obtain R 2 The two ends of the corresponding perfluoropolyether chain have the same two R 3 The corresponding structure and leaving group of the intermediate compound 2-2 (third reaction).

[0358] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1-2a is reacted with the leaving group disposed at one end of the intermediate compound 2-2 to obtain the intermediate compound 2-5 (fourth reaction).

[0359] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1-2b is reacted with the leaving group of the intermediate compound 2-5 obtained in the fourth reaction to obtain the intermediate compound 2-6 (fifth reaction).

[0360] Next, make R 1 -(CH2) in the side chain portion of the terminal group represented by formula (3-3) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 2-6 to obtain the intermediate compound 2-7 (sixth reaction).

[0361] Next, make R 4 -(CH2) in the side chain portion of the terminal group represented by formula (3-3) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 2-7 (seventh reaction).

[0362] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 2 and R 1 and R 4 is the terminal group shown in formula (3-3), R 1 With R 4 Different compounds.

[0363] [Tenth Manufacturing Method (When x is 2)]

[0364] (R 1 is the terminal group shown in formula (3-3), R 4In the case of a terminal group represented by formula (3-1), (3-2) or (3-4)

[0365] First, the intermediate compound 2-5 is obtained in the same manner as in the ninth production method (first reaction).

[0366] In addition, the same operation as the third manufacturing method is performed to manufacture a 4 Side R 2 One end of the corresponding perfluoropolyether chain has 4 The corresponding radical is the intermediate compound 1b (second reaction).

[0367] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1b is reacted with the leaving group of the intermediate compound 2-5 to obtain the intermediate compound 2-8 (third reaction).

[0368] Next, make R 1 -(CH2) in the side chain portion of the terminal group represented by formula (3-3) u The halogen compound of the protected hydroxyl group corresponding to -OH reacts with the secondary hydroxyl group of the side chain portion forming the terminal group represented by the formula (3-3) possessed by the intermediate compound 2-8 (fourth reaction).

[0369] By performing a deprotection reaction using a known method after the above steps, it is possible to produce a compound wherein x in the formula (1) is 2 and R 1 is the terminal group shown in formula (3-3), R 4 A compound having a terminal group represented by formula (3-1), (3-2) or (3-4).

[0370] [Eleventh Manufacturing Method (When x is 2)]

[0371] (2 R 3 different, at least one of which is a divalent linking group represented by formula (2-1) or (2-2), R 1 and R 4 In the case of a terminal group represented by formula (3-1), (3-2) or (3-4)

[0372] Intermediate compound 2-9 can be produced by the method shown below, or by using intermediate compound 2-9 instead of intermediate compound 2-1 in the sixth production method.

[0373] That is, prepare R at the center of the molecule in formula (1) 2The corresponding perfluoropolyether chain has a fluorochemical compound having a hydroxymethyl group (-CH2OH) at both ends. Next, the hydroxyl group of the hydroxymethyl group at one end of the fluorochemical compound is connected to a fluorochemical compound having an R 3 Then, the resulting compound is reacted with another R 3 The corresponding epoxy and alkenyl compounds react.

[0374] Then, m-chloroperbenzoic acid (mCPBA) is allowed to act on the generated compound to oxidize the olefinic group. 2 One end of the corresponding perfluoropolyether chain has an R 3 The corresponding epoxy group has at the other end the same radical as the other R in formula (1) 3 The corresponding epoxy intermediate compound 2-9.

[0375] (2 R 3 different, at least one of which is a divalent linking group represented by formula (2-1) or (2-2), R 1 and R 4 In the case of a terminal group represented by formula (3-3)

[0376] Intermediate compound 2-10 can be produced by the method shown below, or by using intermediate compound 2-10 instead of intermediate compound 2-2 in the seventh production method.

[0377] That is, prepare R at the center of the molecule in formula (1) 2 The corresponding perfluoropolyether chain has a fluorochemical compound having a hydroxymethyl group (-CH2OH) at both ends. Next, the hydroxyl group of the hydroxymethyl group at one end of the fluorochemical compound is connected to a fluorochemical compound having an R 3 The corresponding leaving group is reacted with the protected hydroxyl compound. Then, the generated compound is reacted with another R 3 The corresponding leaving group reacts with the protected hydroxyl compound.

[0378] Thus, R in the center of the molecule in formula (1) is obtained. 2 One end of the corresponding perfluoropolyether chain has an R 3 The corresponding structure and leaving group, at the other end having another R in formula (1) 3 The corresponding structure and leaving group of the intermediate compound 2-10.

[0379] [Lubricant for magnetic recording media]

[0380] The lubricant for a magnetic recording medium according to the present embodiment contains a fluorine-containing ether compound represented by the above formula (1).

[0381] The lubricant of the present embodiment may be mixed with known materials used as lubricant materials as needed within a range not impairing the properties due to the inclusion of the fluorine-containing ether compound represented by the above formula (1).

[0382] 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).

[0383] The known material to be mixed with the lubricant of the present embodiment preferably has a number average molecular weight of 1,000 to 10,000.

[0384] 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, and further preferably 90% by mass or more.

[0385] 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 having excellent floating stability and a high sticking suppression effect.

[0386] [Magnetic recording media]

[0387] 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.

[0388] 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.

[0389] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0390] 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 .

[0391] "Substrate"

[0392] 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.

[0393] 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.

[0394] "Attachment Layer"

[0395] 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.

[0396] 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.

[0397] "Soft magnetic layer"

[0398] The soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer formed 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 antiferromagnetically coupled (AFC) by sandwiching an intermediate layer formed of a Ru film between the two soft magnetic films.

[0399] Examples of the material of the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy.

[0400] 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. Thus, the amorphization of the first soft magnetic film and the second soft magnetic film is promoted. 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.

[0401] The soft magnetic layer 13 can be formed by, for example, sputtering.

[0402] "1st base layer"

[0403] 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.

[0404] 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.

[0405] The first base layer 14 can be formed by, for example, sputtering.

[0406] "Second base layer"

[0407] The second underlayer 15 is a layer controlled so as to improve the orientation of the magnetic layer 16. The second underlayer 15 is preferably a layer formed of Ru or a Ru alloy.

[0408] The second base layer 15 may be a single layer or a plurality of layers. When the second base layer 15 is a plurality of layers, all layers may be made of the same material or at least one layer may be made of a different material.

[0409] The second base layer 15 can be formed by, for example, sputtering.

[0410] "Magnetic layer"

[0411] The magnetic layer 16 is formed of a magnetic film whose easy magnetization axis is oriented vertically or horizontally with respect to the substrate surface. The magnetic layer 16 is a layer containing Co and Pt. In order to improve the SNR characteristics, the magnetic layer 16 may be a layer containing oxide, Cr, B, Cu, Ta, Zr, etc.

[0412] 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 .

[0413] The magnetic layer 16 may be composed of a single layer or a plurality of magnetic layers formed of materials having different compositions.

[0414] 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.

[0415] The first magnetic layer may contain one or more elements selected from the group consisting of B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides.

[0416] The second magnetic layer can be made of the same material as that of the first magnetic layer. The second magnetic layer preferably has a granular structure.

[0417] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, Pt and not containing oxides. 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 in addition to Co, Cr, and Pt.

[0418] 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 formed 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.

[0419] The non-magnetic layer arranged between adjacent magnetic layers of the magnetic layer 16 can be suitably made of, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 represents one or more elements selected from Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Ti, V, B), etc.

[0420] An alloy material containing oxide, metal nitride, or metal carbide is preferably used 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.

[0421] The non-magnetic layer can be formed by, for example, sputtering.

[0422] In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer with its easy magnetization axis oriented perpendicularly to the substrate surface. The magnetic layer 16 may be an in-plane magnetic recording magnetic layer.

[0423] 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.

[0424] "Protective layer"

[0425] The protective layer 17 protects the magnetic layer 16. The protective layer 17 may be formed 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.

[0426] 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).

[0427] 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 chlorine 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.

[0428] 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.

[0429] 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.

[0430] 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.

[0431] "Lubricating layer"

[0432] 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.

[0433] like Figure 1As shown, the lubricating layer 18 is formed in contact with the protective layer 17. The lubricating layer 18 is formed by applying the lubricant for a magnetic recording medium of the above-mentioned embodiment onto the protective layer 17. Therefore, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.

[0434] 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 with a particularly high bonding force. As a result, it is easy to obtain a magnetic recording medium 10 that can cover the surface of the protective layer 17 with a high coverage rate even if the lubricating layer 18 is thin, and can effectively prevent contamination of the surface of the magnetic recording medium 10.

[0435] 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.

[0436] "Method for forming a lubricating layer"

[0437] 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.

[0438] 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.

[0439] 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 Depompico Mitsui Co., Ltd.).

[0440] 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.

[0441] When the dipping method is used, for example, the following method can be used. First, the substrate 11 on which each layer up to the protective layer 17 is formed is dipped in the lubricating layer forming solution placed in the dipping tank of the dipping coating device. Next, the substrate 11 is pulled out of the dipping tank at a predetermined speed. Thus, the lubricating layer forming solution is applied to the surface of the substrate 11 on the protective layer 17.

[0442] 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.

[0443] 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.

[0444] 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.

[0445] 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.

[0446] 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. In 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. The lubricating layer 18 has good floating stability and a high adhesion suppression effect. Therefore, the magnetic recording medium 10 of the present embodiment has excellent reliability and durability. 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 work 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.

[0447] Example

[0448] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples. In addition, the present invention is not limited to the following examples.

[0449] [Example 1]

[0450] The compound represented by the above formula (AA) was obtained by the method shown below.

[0451] (First reaction)

[0452] In a 100 mL eggplant flask under nitrogen atmosphere, add HOCH2CF2O (CF2CF2O)h (CF2O) i 20 g of a compound represented by CF2CH2OH (wherein h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1), 4.12 g of the compound represented by the above formula (5-1), and 20 mL of tert-butyl alcohol were stirred at room temperature until they became uniform to prepare a mixture. 1.12 g of potassium tert-butylate was added to the mixture, and the mixture was stirred at 70°C for 16 hours to react.

[0453] The compound represented by formula (5-1) is synthesized by protecting the hydroxyl group of ethylene glycol monoallyl ether with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0454] 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 9.61 g of the compound represented by the following formula (11) as an intermediate compound 1-1.

[0455]

[0456] (Rf1 in formula (11) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0457] (Second reaction)

[0458] Next, 9.61 g of the compound represented by formula (11) as the intermediate compound 1-1 obtained above, 0.34 g of the compound represented by formula (7-1) above, and 20 mL of tert-butanol were added to a 100 mL eggplant flask under a nitrogen atmosphere, and stirred at room temperature until the mixture became uniform to prepare a mixture. 0.45 g of potassium tert-butoxide was added to the mixture, and the mixture was stirred at 70° C. for 16 hours to react.

[0459] The reaction solution obtained after the reaction was returned to room temperature, 50 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine 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 to obtain 2.81 g of compound (AA) (Rf1 in formula (AA) is the PFPE chain shown in the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0460] The obtained compound (AA) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0461] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (30H), 3.85-4.10 (8H)

[0462] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0463] [Example 2]

[0464] The compound represented by the above formula (AB) was obtained by the method shown below.

[0465] The same operation as in Example 1 was performed except that the compound represented by formula (5-2) was used instead of the compound represented by formula (5-1), thereby obtaining 2.92 g of compound (AB) (Rf1 in formula (AB) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0466] The compound represented by formula (5-2) is synthesized by protecting one hydroxyl group of 1,3-propanediol with dihydropyran and then reacting the hydroxyl group with epibromohydrin.

[0467] The obtained compound (AB) is subjected to 1 H-NMR determination and 19The structure was identified based on the following results from F-NMR measurement.

[0468] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (30H), 3.85-4.10 (8H)

[0469] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0470] [Example 3]

[0471] The compound represented by the above formula (AC) was obtained by the method shown below.

[0472] The same operation as in Example 1 was performed except that the compound represented by formula (5-3) was used instead of the compound represented by formula (5-1), thereby obtaining 2.54 g of compound (AC) (Rf1 in formula (AC) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0473] The compound represented by formula (5-3) is synthesized by protecting the hydroxyl group of 3-butene-1-ol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

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

[0475] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (22H), 3.85-4.10 (8H)

[0476] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0477] [Example 4]

[0478] The compound represented by the above formula (AD) was obtained by the method shown below.

[0479] The same operation as in Example 1 was performed except that the compound represented by formula (5-4) was used instead of the compound represented by formula (5-1), thereby obtaining 2.54 g of compound (AD) (Rf1 in formula (AD) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0480] The compound represented by formula (5-4) is synthesized by allowing 2-(2-bromoethoxy)tetrahydro-2H-pyran to react with the hydroxyl group of 3-butene-1-ol, and then oxidizing it with m-chloroperbenzoic acid.

[0481] The obtained compound (AD) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0482] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (30H), 3.85-4.10 (8H)

[0483] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0484] [Example 5]

[0485] The compound represented by the above formula (AE) was obtained by the method shown below.

[0486] The same operations as in Example 1 were performed except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), thereby obtaining 2.84 g of compound (AE) (Rf1 in formula (AE) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0487] The compound represented by formula (5-5) is synthesized by subjecting the compound represented by formula (5-1) to an addition reaction with allyl alcohol, protecting the hydroxyl group of the obtained compound with dihydropyran, and further oxidizing the compound with m-chloroperbenzoic acid.

[0488] The obtained compound (AE) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0489] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (42H), 3.85-4.10 (8H)

[0490] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0491] [Example 6]

[0492] The compound represented by the above formula (AF) was obtained by the method shown below.

[0493] The same operations as in Example 1 were performed except that the compound represented by formula (5-6) was used instead of the compound represented by formula (5-1), thereby obtaining 2.84 g of compound (AF) (Rf1 in formula (AF) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0494] The compound represented by formula (5-6) is synthesized by subjecting the compound represented by formula (5-3) to an addition reaction with allyl alcohol, protecting the hydroxyl group of the obtained compound with dihydropyran, and further oxidizing the compound with m-chloroperbenzoic acid.

[0495] The obtained compound (AF) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0496] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (34H), 3.85-4.10 (8H)

[0497] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0498] [Example 7]

[0499] The compound represented by the above formula (AG) was obtained by the method shown below.

[0500] The same operations as in Example 1 were performed except that the compound represented by formula (5-7) was used instead of the compound represented by formula (5-1), thereby obtaining 2.84 g of compound (AG) (Rf1 in formula (AG) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0501] The compound represented by formula (5-7) is synthesized by subjecting the compound represented by formula (5-1) to an addition reaction with 3-butene-1-ol, protecting the hydroxyl group of the obtained compound with dihydropyran, and further oxidizing the compound with m-chloroperbenzoic acid.

[0502] The obtained compound (AG) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0503] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (42H), 3.85-4.10 (8H)

[0504] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0505] [Example 8]

[0506] The compound represented by the above formula (AH) was obtained by the method shown below.

[0507] (First reaction)

[0508] In the same manner as in the first reaction of Example 1, a compound represented by formula (11) was obtained as an intermediate compound 1a.

[0509] (Second reaction)

[0510] The same operation as in the first reaction of Example 1 was carried out except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), thereby obtaining a compound represented by formula (12) as an intermediate compound 1b.

[0511]

[0512] (Rf1 in formula (12) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0513] (Third reaction)

[0514] Next, 9.66 g of the compound represented by formula (11) as the intermediate compound 1a obtained above, 0.69 g of the compound represented by formula (9-1) above, and 20 mL of tert-butanol were added to a 100 mL eggplant flask under a nitrogen atmosphere, and stirred at room temperature until the mixture became uniform to prepare a mixture. 0.45 g of potassium tert-butoxide was added to the mixture, and the mixture was stirred at 70° C. for 16 hours to react.

[0515] 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 oxidized with meta-chloroperbenzoic acid and purified by silica gel column chromatography to obtain 6.48 g of the compound represented by the following formula (13) as an intermediate compound 1-4.

[0516]

[0517] (Rf1 in formula (13) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0518] (Fourth reaction)

[0519] Next, 7.21 g of the compound represented by formula (12) as the intermediate compound 1b obtained above, 6.48 g of the compound represented by formula (13) as the intermediate compound 1-4 obtained above, and 20 mL of tert-butanol were added to a 100 mL eggplant flask under a nitrogen atmosphere, and stirred at room temperature until the mixture became uniform to prepare a mixture. 0.45 g of potassium tert-butoxide was added to the mixture, and the mixture was stirred at 70° C. for 16 hours to react.

[0520] The reaction solution obtained after the reaction was returned to room temperature, 50 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine 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 to obtain 4.34 g of compound (AH) (Rf1 in formula (AH) is the PFPE chain shown in the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0521] The obtained compound (AH) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0522] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (36H), 3.85-4.10 (8H)

[0523] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0524] [Example 9]

[0525] The compound represented by the above formula (AI) was obtained by the method shown below.

[0526] By performing the same operations as in Example 1 except that the compound represented by formula (5-8) was used instead of the compound represented by formula (5-1), 3.06 g of compound (AI) (Rf1 in formula (AI) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0527] The compound represented by formula (5-8) is synthesized by protecting one hydroxyl group of 1,6-hexanediol with dihydropyran and then reacting the 1,6-hexanediol with epibromohydrin.

[0528] The obtained compound (AI) is 1 H-NMR determination and 19The structure was identified based on the following results from F-NMR measurement.

[0529] 1 H-NMR (acetone-D6): δ [ppm] = 1.25-1.85 (16H), 3.40-3.85 (30H), 3.85-4.10 (8H)

[0530] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0531] [Example 10]

[0532] The compound represented by the above formula (AJ) was obtained by the method shown below.

[0533] By performing the same operations as in Example 1 except that the compound represented by formula (5-9) was used instead of the compound represented by formula (5-1), 2.81 g of compound (AJ) (Rf1 in formula (AJ) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0534] The compound represented by formula (5-9) is synthesized by protecting the hydroxyl group of 7-octen-1-ol with dihydropyran and then oxidizing it with m-fluoroperbenzoic acid.

[0535] The obtained compound (AJ) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0536] 1 H-NMR (acetone-D6): δ [ppm] = 1.25-1.85 (16H), 3.40-3.85 (22H), 3.85-4.10 (8H)

[0537] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0538] [Example 11]

[0539] The compound represented by the above formula (AK) was obtained by the method shown below.

[0540] By performing the same operations as in Example 1 except that the compound represented by formula (5-10) was used instead of the compound represented by formula (5-1), 2.61 g of compound (AK) (Rf1 in formula (AK) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0541] The compound represented by formula (5-10) is synthesized by protecting the hydroxyl group of 2-bromoethanol with dihydropyran, further reacting it with 5-hexen-1-ol, and then oxidizing it with m-chloroperbenzoic acid.

[0542] The obtained compound (AK) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0543] 1 H-NMR (acetone-D6): δ [ppm] = 1.25-1.85 (12H), 3.40-3.85 (30H), 3.85-4.10 (8H)

[0544] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0545] [Example 12]

[0546] The compound represented by the above formula (AL) was obtained by the method shown below.

[0547] Instead of the compound represented by formula (5-1), the compound represented by formula (5-11) was used. The same operations as in Example 1 were carried out to obtain 2.42 g of compound (AL) (Rf1 in formula (AL) is the PFPE chain represented by the above formula (4-1). Among the two R.f1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0548] The compound represented by formula (5-11) can be synthesized by reacting N-(2-hydroxyethyl)acetamide with epibromohydrin.

[0549] The obtained compound (AL) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0550] 1H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (6H), 3.40-3.85 (28H), 3.85-4.10 (8H), 6.30-6.50 (2H)

[0551] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0552] [Example 13]

[0553] The compound represented by the above formula (AM) was obtained by the method shown below.

[0554] Instead of the compound represented by formula (5-1), the compound represented by formula (5-12) was used. The same operations as in Example 1 were carried out to obtain 2.65 g of compound (AM) (Rf1 in formula (AM) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0555] The compound represented by formula (5-12) is synthesized by reacting 2-cyanoethanol with epibromohydrin.

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

[0557] 1 H-NMR (acetone-D6): δ [ppm] = 2.00-2.10 (4H), 3.40-3.85 (24H), 3.85-4.10 (8H)

[0558] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0559] [Example 14]

[0560] The compound represented by the above formula (AN) was obtained by the method shown below.

[0561] By performing the same operations as in Example 1, 2.41 g of compound (AN) (Rf1 in formula (AN) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0562] The compound represented by formula (7-2) is synthesized by oxidizing allyl glycidyl ether with m-chloroperbenzoic acid.

[0563] The obtained compound (AN) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0564] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (34H), 3.85-4.10 (8H)

[0565] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0566] [Example 15]

[0567] The compound represented by the above formula (AO) was obtained by the method shown below.

[0568] The same operations as in Example 1 were performed, except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), and the compound represented by formula (7-2) was used instead of the compound represented by formula (7-1), to obtain 2.41 g of compound (AO) (Rf1 in formula (AO) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

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

[0570] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (46H), 3.85-4.10 (8H)

[0571] 19F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0572] [Example 16]

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

[0574] By performing the same operations as in Example 1, 2.56 g of compound (AP) (Rf1 in formula (AP) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0575] The compound represented by formula (7-3) is synthesized by reacting two molecules of allyl alcohol with one molecule of epibromohydrin, protecting the secondary hydroxyl group of the compound produced after the reaction with dihydropyran, and further oxidizing with m-chloroperbenzoic acid.

[0576] The obtained compound (AP) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0577] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (40H), 3.85-4.10 (8H)

[0578] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0579] [Example 17]

[0580] The compound represented by the above formula (AQ) was obtained by the method shown below.

[0581] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2O (CF2CF2CF2O). jA compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) was obtained by the same operation as in Example 1 (Rf1 in formula (AQ) is the PFPE chain represented by the above formula (4-2). In Rf2, j representing the average degree of polymerization is 4.5) 2.74 g.

[0582] The obtained compound (AQ) was 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0583] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (30H), 3.85-4.10 (8H)

[0584] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (36F), -86.4 (8F), -124.3 (8F), -130.0 to -129.0 (18F)

[0585] [Example 18]

[0586] The compound represented by the above formula (AR) was obtained by the method shown below.

[0587] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2CF2O (CF2CF2CF2CF2O). k A compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CF2CH2oH (where k representing the average degree of polymerization is 3.0) was obtained by the same operation as in Example 1 to obtain 2.67 g of compound (AR) (Rf3 in formula (AR) is the PFPE chain represented by the above formula (4-3). In Rf3, k representing the average degree of polymerization is 3.0).

[0588] The obtained compound (AR) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0589] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (30H), 3.85-4.10 (8H)

[0590] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (32F), -122.5 (8F), -126.0 (24F), -129.0 to -128.0 (8F)

[0591] [Example 19]

[0592] The compound represented by the above formula (AS) was obtained by the method shown below.

[0593] (First reaction)

[0594] In the same manner as in the first reaction of Example 1, a compound represented by formula (11) was obtained as an intermediate compound 1-2.

[0595] (Second reaction)

[0596] Next, 9.25 g of the compound represented by formula (11) as the intermediate compound 1-2 obtained above, 2.15 g of the compound represented by the following formula (14), and 20 mL of dimethylformamide were added to a 100 mL eggplant flask under a nitrogen atmosphere, and stirred at room temperature until the mixture became uniform to prepare a mixture. 2.88 g of cesium carbonate was added to the mixture, and the mixture was stirred at 70° C. for 16 hours to react.

[0597]

[0598] (In formula (14), Ts represents a toluenesulfonyl group (p-toluenesulfonyl group).)

[0599] 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 oxidized with meta-chloroperbenzoic acid and purified by silica gel column chromatography to obtain 7.22 g of the compound represented by the following formula (15) as an intermediate compound 1-3.

[0600]

[0601] (Rf1 in formula (15) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0602] (Third reaction)

[0603] Next, 7.21 g of the compound represented by formula (15) as the intermediate compound 1-3 obtained above, 1.51 g of the compound represented by the following formula (16), and 20 mL of dimethylformamide were added to a 100 mL eggplant flask under a nitrogen atmosphere, and stirred at room temperature until the mixture became uniform to prepare a mixture. 0.45 g of sodium hydride was added to the mixture, and the mixture was stirred at 40° C. for 16 hours to react.

[0604]

[0605] (In formula (16), THP represents tetrahydropyranyl.)

[0606] The reaction solution obtained after the reaction was returned to room temperature, 50 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine 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 to obtain 3.51 g of compound (AS) (Rf1 in formula (AS) is the PFPE chain shown in the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0607] The obtained compound (AS) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0608] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (38H), 3.85-4.10 (8H)

[0609] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0610] [Example 20]

[0611] The compound represented by the above formula (AT) was obtained by the method shown below.

[0612] In the first reaction of Example 19, the intermediate compound 1-2 was synthesized by using the compound represented by the following formula (17) instead of the compound represented by the formula (5-1). The same operation as in Example 19 was performed to obtain 3.28 g of compound (AT) (Rf1 in formula (AT) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0613]

[0614] (In formula (17), THP represents tetrahydropyranyl.)

[0615] The compound represented by formula (17) is synthesized by protecting the hydroxyl group of allyl alcohol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0616] The obtained compound (AT) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0617] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (30H), 3.85-4.10 (8H)

[0618] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0619] [Example 21]

[0620] The compound represented by the above formula (AU) was obtained by the method shown below.

[0621] The same operations as in Example 1 were performed except that the compound represented by formula (5-13) was used instead of the compound represented by formula (5-1) in Example 1, thereby obtaining 2.04 g of compound (AU) (Rf1 in formula (AU) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0622] The compound represented by formula (5-13) is synthesized by reacting salicylamide with epibromohydrin.

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

[0624] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (20H), 3.85-4.10 (8H), 6.70-8.20 (12H)

[0625] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0626] [Example 22]

[0627] The compound represented by the above formula (AV) was obtained by the method shown below.

[0628] By performing the same operations as in Example 1, 2.21 g of compound (AV) (Rf1 in formula (AV) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0629] The compound represented by formula (5-14) is synthesized by reacting 3-cyanophenol with epibromohydrin.

[0630] The obtained compound (AV) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0631] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (20H), 3.85-4.10 (8H), 7.20-7.60 (8H)

[0632] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0633] [Example 23]

[0634] The compound represented by the above formula (BA) was obtained by the method shown below.

[0635] The same operation as in Example 1 was performed except that the compound represented by the following formula (18) was used instead of the compound represented by the formula (7-1), thereby obtaining 3.61 g of compound (BA) (Rf1 in the formula (BA) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0636]

[0637] (Rf1 in formula (18) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0638] The compound represented by formula (18) is prepared by making HOCH2CF2O(CF2CF2O) h (CF2O) i The compound represented by CF2CH2OH (wherein h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) is reacted with the compound represented by formula (9-1), and then oxidized with m-chloroperbenzoic acid to synthesize the compound.

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

[0640] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (38H), 3.85-4.10 (12H)

[0641] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0642] [Example 24]

[0643] The compound represented by the above formula (BB) was obtained by the method shown below.

[0644] By performing the same operation as in Example 23, 3.76 g of compound (BB) (Rf1 in formula (BB) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

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

[0646] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (50H), 3.85-4.10 (12H)

[0647] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0648] [Example 25]

[0649] The compound represented by the above formula (BC) was obtained by the method shown below.

[0650] Instead of the compound represented by formula (5-1), the compound represented by formula (5-3) was used. Except for this, the same operation as in Example 23 was carried out to obtain 3.43 g of compound (BC) (Rf1 in formula (BC) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0651] The obtained compound (BC) 1 H-NMR determination and 19 The structure was identified by the following results using F-NMR measurements.

[0652] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (30H), 3.85-4.10 (12H)

[0653] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0654] [Example 26]

[0655] The compound represented by the above formula (BD) was obtained by the method shown below.

[0656] Instead of the compound represented by formula (5-1), the compound represented by formula (5-4) was used. Except for this, the same operation as in Example 23 was performed to obtain 3.43 g of compound (BD) (Rf1 in formula (BD) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0657] The obtained compound (BD) was 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0658] 1 H-NMR (acetone-D6): δ [ppm] = 1.65-1.85 (4H), 3.40-3.85 (42H), 3.85-4.10 (12H)

[0659] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0660] [Example 27]

[0661] The compound represented by the above formula (BE) was obtained by the method shown below.

[0662] Instead of the compound represented by formula (5-1), the compound represented by formula (5-11) was used. Except for this, the same operation as in Example 23 was carried out to obtain 3.56 g of compound (BE) (Rf1 in formula (BE) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0663] The obtained compound (BE) was 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0664] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (6H), 3.40-3.85 (36H), 3-85-4.10 (12H), 6.30-6.50 (2H) 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0665] [Example 28]

[0666] The compound represented by the above formula (BF) was obtained by the method shown below.

[0667] Instead of the compound represented by formula (5-1), the compound represented by formula (5-12) was used. Except for this, the same operation as in Example 23 was carried out to obtain 3.82 g of compound (BF) (Rf1 in formula (BF) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0668] The obtained compound (BF) is 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0669] 1 H-NMR (acetone-D6): δ [ppm] = 2.00-2.10 (4H), 3.40-3.85 (32H), 3.85-4.10 (12H)

[0670] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0671] [Example 29]

[0672] The compound represented by the above formula (BG) was obtained by the method shown below.

[0673] By performing the same operations as in Example 23, 3.06 g of compound (BG) (Rf1 in formula (BG) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0674] The obtained compound (BG) was 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0675] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (46H), 3.85-4.10 (12H)

[0676] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0677] [Example 30]

[0678] The compound represented by the above formula (BH) was obtained by the method shown below.

[0679] By performing the same operations as in Example 23, 3.14 g of compound (BH) (Rf1 in formula (BH) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) was obtained.

[0680] The compound represented by formula (9-3) is synthesized by reacting two molecules of allyl alcohol with one molecule of epibromohydrin, protecting the secondary hydroxyl group of the generated compound with dihydropyran, and oxidizing one carbon-carbon double bond with m-fluoroperbenzoic acid.

[0681] The obtained compound (BH) 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0682] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (58H), 3.85-4.10 (12H)

[0683] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0684] [Example 31]

[0685] The compound represented by the above formula (BI) was obtained by the method shown below.

[0686] The same operation as in Example 23 was performed except that the compound represented by the following formula (19) was used instead of the compound represented by the formula (18), thereby obtaining 3.24 g of compound (BI) (Rf1 in formula (BI) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0687]

[0688] (Rf1 in formula (19) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5)

[0689] The compound represented by formula (19) is prepared by the following method. h (CF2O) i A compound represented by CF2CH2OH (wherein h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) was reacted. Next, the generated compound was reacted with epibromohydrin. Then, m-chloroperbenzoic acid was allowed to act on the generated compound to oxidize the carbon-carbon double bond to synthesize.

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

[0691] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (36H), 3.85-4.10 (12H)

[0692] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0693] [Example 32]

[0694] The compound represented by the above formula (BJ) was obtained by the method shown below.

[0695] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2O (CF2CF2CF2O). jA compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CH2OH (where j representing the average degree of polymerization is 4.5) was obtained by the same operation as in Example 23 to obtain 2.74 g of compound (BJ) (Rf2 in formula (BJ) is the PFPE chain represented by the above formula (4-2). Among the three Rf2s, j representing the average degree of polymerization is 4.5).

[0696] The obtained compound (BJ) was 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0697] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (38H), 3.85-4.10 (12H)

[0698] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (54F), -86.4 (12F), -124.3 (12F), -130.0 to -129.0 (27F)

[0699] [Example 33]

[0700] The compound represented by the above formula (BK) was obtained by the method shown below.

[0701] Instead of the compound represented by formula (5-1), the compound represented by formula (5-12) was used. Except for this, the same operations as in Example 29 were performed to obtain 3.21 g of compound (BK) (Rf1 in formula (BK) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0702] The obtained compound (BK) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0703] 1 H-NMR (acetone-D6): δ [ppm] = 2.00-2.10 (4H), 3.40-3.85 (40H), 3.85-4.10 (12H)

[0704] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0705] The compounds (AA) to (AV) and (BA) to (BK) of Examples 1 to 33 obtained in this manner are substituted into the formula (1), respectively, and the values ​​of x and R are changed. 1 , R 2 , R 3 , R 4 The structures of are shown in Table 1. In addition, except for compound (AH), all R 1 With R 4 The structure is the same.

[0706] Table 1

[0707]

[0708] [Comparative Example 1]

[0709] According to the method described in Patent Document 1, a compound represented by the following formula (ZA) was synthesized.

[0710]

[0711] (Rf1 in formula (ZA) is the PFPE chain represented by the above formula (4-1); in the two Rf1, h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0.)

[0712] [Comparative Example 2]

[0713] According to the method described in Patent Document 2, a compound represented by the following formula (ZB) was synthesized.

[0714]

[0715] (Rf1 in formula (ZB) is the PFPE chain represented by the above formula (4-1); in the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0716] [Comparative Example 3]

[0717] According to the method described in Patent Document 3, a compound represented by the following formula (ZC) was synthesized.

[0718]

[0719] (Rf1 in formula (ZC) is the PFPE chain represented by the above formula (4-1); in the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0720] [Comparative Example 4]

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

[0722]

[0723] (Rf2 in formula (ZD) is the PFPE chain represented by the above formula (4-2); in the two Rf2, j indicating the average degree of polymerization is 4.5.)

[0724] [Comparative Example 5]

[0725] According to the method described in Patent Document 5, a compound represented by the following formula (ZE) was synthesized.

[0726]

[0727] (Rf1 in formula (ZE) is the PFPE chain represented by the above formula (4-1); in the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0728] [Comparative Example 6]

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

[0730]

[0731] (Rf1 in formula (ZF) is the PFPE chain represented by the above formula (4-1); in the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0732] The same operations as in Example 1 were performed, except that the compound represented by the above formula (17) was used instead of the compound represented by the formula (5-1), and the compound represented by the formula (7-2) was used instead of the compound represented by the formula (7-1), to obtain 2.21 g of compound (ZF) (Rf1 in the formula (ZF) is the PFPE chain represented by the above formula (4-1). Among the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0733] The obtained compound (ZF) is 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0734] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (26H), 3.85-4.10 (8H)

[0735] 19F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0736] [Comparative Example 7]

[0737] According to the method described in Patent Document 6, a compound represented by the following formula (ZG) was synthesized.

[0738]

[0739] (Rf1 in formula (ZG) is the PFPE chain represented by the above formula (4-1); among the three Rf1, h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0.)

[0740] [Comparative Example 8]

[0741] According to the method described in Patent Document 7, a compound represented by the following formula (ZH) was synthesized.

[0742]

[0743] (Rf1 in formula (ZH) is the PFPE chain represented by the above formula (4-1); in the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0744] [Comparative Example 9]

[0745] According to the method described in Patent Document 8, a compound represented by the following formula (ZI) was synthesized.

[0746]

[0747] (Rf1 in formula (ZI) is the PFPE chain represented by the above formula (4-1); among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0748] The number average molecular weight (Mn) of the compounds of Examples 1 to 33 and Comparative Examples 1 to 9 obtained in this manner was measured by the above-mentioned method. The results are shown in Tables 2 and 3.

[0749] Next, a lubricant layer forming solution was prepared by the method described below using the compounds obtained in Examples 1 to 33 and Comparative Examples 1 to 9. 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 33 and Comparative Examples 1 to 9.

[0750] "Lubricating layer forming solution"

[0751] The compounds obtained in Examples 1 to 33 and Comparative Examples 1 to 9 were dissolved in a fluorine-based solvent, Batorel (registered trademark) XF (trade name, manufactured by DuPont Mitsui Chemical Co., Ltd.), respectively, to form a film with a thickness of 100 Å to 200 Å when applied on the protective layer. The solution was diluted with Biotrel XF in a manner of 100% to prepare a lubricating layer forming solution.

[0752] "Magnetic recording media"

[0753] 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.

[0754] On the protective layer of the magnetic recording medium formed with each layer up to the protective layer, the lubricating layer forming solutions of Examples 1 to 33 and Comparative Examples 1 to 9 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 lifting speed of 1.2 mm / sec.

[0755] 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.

[0756] (Film thickness measurement)

[0757] The film thickness of the lubricating layer of the magnetic recording media of Examples 1 to 33 and Comparative Examples 1 to 9 obtained in this manner was measured using a Fourier transform infrared spectrophotometer (FT-IR, trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific).

[0758] Next, the magnetic recording media of Examples 1 to 33 and Comparative Examples 1 to 9 were subjected to the following flying stability test and adhesion characteristic test.

[0759] [Floating stability test]

[0760] The following sliding test and reliability measurement were performed, and the floating stability was evaluated based on the following evaluation criteria. The results are shown in Tables 2 and 3.

[0761] "Sliding Test"

[0762] 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 will become a cause of collision between the magnetic head and the protrusion, causing damage to the magnetic head, or defects in the magnetic recording medium. In the sliding test, 50 pieces of magnetic recording media are checked for protrusions with a height greater than the floating amount on the surface.

[0763] 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 otherwise it was judged to be qualified. Furthermore, the number of magnetic recording media judged to be qualified among 50 magnetic recording media was used for evaluation.

[0764] "Reliability Measurement"

[0765] When the above-mentioned sliding test is carried out, the noise temporarily increases. Although it is the same position on the magnetic recording medium, in multiple measurements, sometimes a signal caused by the collision with the protrusion on the surface is detected or not detected. 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 unevenness of the lubricant layer or the presence of relatively soft foreign matter. Therefore, a sliding test is carried out on the magnetic recording medium, and the total number of detected reliability is divided by the number of magnetic recording media (50 pieces) on which the sliding test is carried out, so as to calculate the reliability average value, which is used as an indicator of the smoothness and cleanliness of the lubricant layer.

[0766] “Evaluation Benchmarks”

[0767] A+: The number of qualified pieces in the sliding test is more than 45 and the average reliability value is less than 0.5

[0768] A: The number of qualified pieces in the sliding test is more than 45 and the reliability average is more than 0.5 and less than 1.0

[0769] B: 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

[0770] C: The number of qualified pieces in the sliding test is 45 or more and the reliability average is 5.0 or more

[0771] D: The number of qualified pieces in the sliding test is less than 45 pieces

[0772] [Adhesion characteristics test]

[0773] The magnetic recording medium and the magnetic head were installed on the spin stand, and the magnetic head was rotated at room temperature under reduced pressure (about 250 Torr) to float the magnetic head at a fixed point for 10 minutes. Then, the surface of the magnetic head opposite to the magnetic recording medium was analyzed using an ESCA (Electron Spectroscopy for Chemical Analysis) analysis device. The intensity of the peak derived from fluorine obtained by the analysis using the ESCA analysis device (signal intensity (au)) represents the amount of lubricant attached to the magnetic head. Using the obtained signal intensity, the adhesion characteristics were evaluated using the evaluation criteria shown below.

[0774] “Evaluation Benchmarks”

[0775] A+: Signal strength is less than 120 (almost no adhesion)

[0776] A: Signal strength is above 120 and less than 180 (very little adhesion)

[0777] B: Signal strength is above 180 and less than 300 (small amount of adhesion)

[0778] C: Signal strength is 300 or more and less than 1000 (large amount of adhesion)

[0779] D: Signal strength 1000 or more (very high amount of adhesion)

[0780] [Comprehensive evaluation]

[0781] From the results of the floating stability test and the adhesion property test, a comprehensive evaluation was performed based on the following criteria.

[0782] “Comprehensive evaluation”

[0783] A: Both the evaluation of the floating stability test and the evaluation of the adhesion characteristics test are A+ or A

[0784] B: One of the evaluations in the floating stability test and the adhesion characteristics test is B, and the other is A+, A, or B

[0785] C: One of the evaluations in the floating stability test and the adhesion characteristics test is C, and the other is A+, A, B, or C

[0786] D: At least one of the evaluation in the floating stability test and the evaluation in the adhesion characteristics test is D

[0787] Table 2

[0788]

[0789] Table 3

[0790]

[0791] As shown in Table 2, R 1 and R 4 is a terminal group represented by any one of the formulae (3-1) to (3-4), and is disposed between adjacent perfluoropolyether chains. 3 The evaluation of the floating stability test and adhesion property test of the magnetic recording media of Examples 1 to 33 for the compounds (AA) to (AV), (BA) to (BK) represented by formula (1) in which at least one of the compounds is a divalent linking group represented by formula (2-1) or (2-2) is any one of A+, A, and B, and the comprehensive evaluation is all A or B. Therefore, it can be confirmed that the floating stability of the lubricating layer of the magnetic recording media of Examples 1 to 33 is good and the adhesion suppression effect is high.

[0792] The evaluation of the floating stability test and adhesion characteristics test of the magnetic recording media of Examples 1 to 4, 12 to 14, 17 to 23, 25 to 29, 32, and 33 using compounds (AA) to (AD), (AL) to (AN), (AQ) to (AV), (BA), (BC) to (BG), (BJ), and (BK) was either A+ or A in the floating stability test and adhesion characteristics test, and the overall evaluation was A.

[0793] x R of compounds (AA) to (AD), (AL) to (AN), (AQ) to (AT), (BA), (BC) to (BG), (BJ), (BK) 3 The number of hydroxyl groups contained is 2, R 1 and R 4 The number of polar groups contained is 2, R 1 and R 4 Each of the free formulas (3-1) to (3-3) indicates that R 1 and R 4 The alkylene chain of the main chain portion is not too long (the total of p and r in formula (3-1) is 3 or less, t in formula (3-2) is 4 or less, and the total number of carbon atoms and oxygen atoms in Y in formula (3-3) is 3 or less). In addition, R 3 The number of hydroxyl groups contained is 2, R 1 and R 4 The number of polar groups contained is 2, R 1 and R 4 Expressed by formula (3-4).

[0794] Among the above compounds, R 3 Formula (2-1), R 1 and R 4In Examples 12, 21, and 27 containing compounds (AL), (AU), and (BE) having a group having an amide bond, the evaluation in the floating stability test was A, and the evaluation in the adhesion property test was A+, which were excellent results.

[0795] In addition, when x is 2 and R 3 Formula (2-2) and 1 = 1, R 1 and R 4 In Example 33 of the cyano group-containing compound (BK), the evaluation in the floating stability test was A+, and the evaluation in the adhesion property test was A, which were excellent results.

[0796] For the compounds of Examples 12, 21, 27 and 33, it is estimated that R 1 and R 4 The strength of the interaction with the active sites on the protective layer and R 3 The strength of the interaction with the active sites on the protective layer is appropriately balanced.

[0797] On the other hand, in Comparative Examples 1 to 9 using compounds (ZA) to (ZI), the evaluations in the floating stability test and the adhesion property test were C or D, and the overall evaluation was D.

[0798] More specifically, in Comparative Examples 1, 2, 8, and 9 using compounds (ZA), (ZB), (ZH), and (ZI) in which the linking group disposed between adjacent perfluoropolyether chains contained only one hydroxyl group, the results of the floating stability test were D. This is considered to be because the number of hydroxyl groups in the linking group was insufficient, so that the linking group and the protective layer could not interact sufficiently, and the center portion of the fluorinated ether compound floated, thereby losing the smoothness of the lubricating layer.

[0799] In addition, in Comparative Examples 3 and 4 using compounds (ZC) and (ZD) in which the linking group disposed between adjacent perfluoropolyether chains has two hydroxyl groups, but a rigid alkylene chain formed by four methylene groups is disposed between carbon atoms to which the hydroxyl groups are bonded, the result of the floating stability test is D. This is presumably because the rigid alkylene chain of the linking group restricts the movement of the hydroxyl groups contained in the linking group. As a result, sufficient interaction between the linking group portion of the compound and the protective layer cannot be obtained, the center portion of the compound floats, and the smoothness of the lubricating layer is lost.

[0800] In addition, in the comparative examples 1, 4 to 7 using compounds (ZA), (ZD) to (ZG) having terminal groups in which carbon atoms to which hydroxyl groups are bonded are directly bonded, the evaluation of the adhesion property test is D. For these compounds, since the hydroxyl groups contained in the terminal groups are close to each other, the intramolecular interaction between the close hydroxyl groups occurs preferentially over the interaction between the hydroxyl groups and the protective layer. Therefore, it can be considered that sufficient interaction between the terminal groups and the protective layer cannot be obtained, and the terminal portion of the compound floats and is easily adsorbed on the magnetic head.

[0801] In addition, in Comparative Example 9 using a compound (ZI) having only one hydroxyl group in one terminal group, the evaluation of the adhesion property test was D. This is presumably because the number of hydroxyl groups in the terminal group is insufficient, thereby failing to obtain sufficient interaction between the terminal group and the protective layer. As a result, it is presumed that the terminal portion of the compound floats and is easily adsorbed to the magnetic head.

[0802] Industrial Availability

[0803] By using the lubricant for a magnetic recording medium containing the fluorine-containing ether compound of the present invention, a lubricating layer having excellent floating stability and a high sticking suppression effect can be formed.

[0804] Explanation of symbols

[0805] 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), x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; (x+1) R 2 They may be partly or completely the same, or they may be different; R 3 is a divalent linking group having a hydroxyl group; x R 3 At least one of them is a divalent linking group represented by the following formula (2-1) or (2-2); when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 2 to 4 polar groups, and the number of carbon atoms of the shortest distance between carbon atoms to which adjacent polar groups are bonded is 1 to 9 and has a bond to R 2 The terminal group of the oxygen atom of the methylene group; R 1 and R 4 They can be the same or different; In formula (2-2), l represents an integer of 1 to 2.

2. The fluorinated ether compound according to claim 1, wherein R in the formula (1) 1 and R 4 Each independently contains at least one polar group selected from the group consisting of a hydroxyl group, a cyano group, and a group having an amide bond.

3. The fluorinated ether compound according to claim 1, wherein R in the formula (1) 1 and R 4 Each independently represents a terminal group represented by any one of the following formulae (3-1) to (3-4), In formula (3-1), p represents an integer of 0 to 3, r represents an integer of 1 to 5, and the total value of p and r is 1 to 5; q represents an integer of 0 to 2; A represents a polar group; In formula (3-2), s represents an integer from 0 to 2, and t represents an integer from 1 to 5; In formula (3-3), u represents an integer of 2 to 4; Y represents a linear alkylene group which may have an ether oxygen, or a single bond; when Y is the alkylene group, the total number of carbon atoms and oxygen atoms possessed by Y is 1 to 5; In the formula (3-4), v represents an integer of 1 to 3; and B represents a polar group in which a hydrogen atom at any position of the benzene ring is substituted.

4. The fluorinated ether compound according to any one of claims 1 to 3, wherein R in the formula (1) 1 The polar group and R 4 The total number of polar groups possessed is 4 to 6.

5. The fluorinated ether compound according to any one of claims 1 to 3, wherein R in the formula (1) 1 With R 4 same.

6. The fluorinated ether compound according to any one of claims 1 to 3, wherein the x R in the formula (1) 3 At least one of them is represented by the above formula (2-1).

7. The fluorinated ether compound according to any one of claims 1 to 3, wherein the (x+1)th R in the formula (1) 2 Each is independently a perfluoropolyether chain represented by the following formula (4); -(CF2) w1-O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4) In formula (4), 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 the number of 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 (4).

8. The fluorinated ether compound according to any one of claims 1 to 3, wherein the (x+1)th R in the formula (1) 2 Each independently represents any one selected from the perfluoropolyether chains represented by the following formulae (4-1) to (4-4); -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1) In formula (4-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2) In formula (4-2), j represents the average degree of polymerization and is 1 to 15; -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3) In formula (4-3), k represents the average degree of polymerization and is 1 to 10; -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4) In formula (4-4), w8 and w9 represent average polymerization degrees, and each independently represents 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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