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

Abstract

The present invention provides a fluorine-containing ether compound represented by the following formula. In the formula (I), R1-CH2-R2 [-CH2-R3-CH2-R2] x-CH2-R4 (x is 1-2, R2 is a perfluoropolyether chain, and R3 is a divalent linking group with 1-4 polar groups), and the general formula (I) is shown in the description. And each of R1 and R4 represents a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms. At least one of R1 and R4 is-O-X-CH (OH)-CH2OH (X is a divalent organic group having 2 to 30 carbon atoms and optionally containing at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms). And X contains at least one carbon atom that is not bonded to both a polar group and an ether oxygen atom).

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. 2023-074982 filed in Japan on April 28, 2023, and the contents are incorporated herein by reference. Background Art

[0003] In order to increase the recording density of magnetic recording and reproducing devices, magnetic recording media suitable for high recording density are being developed.

[0004] In the past, there was a magnetic recording medium in which a recording layer was formed on a substrate and a protective layer composed of carbon or the like was 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 providing the protective layer on the recording layer does not allow the magnetic recording medium to obtain sufficient durability. Therefore, a lubricant is generally applied to the surface of the protective layer to form a lubricating layer.

[0005] As a lubricant used in 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 end of a fluorine-based polymer having a repeating structure containing -CF2- has been proposed.

[0006] For example, Patent Documents 1 and 2 disclose a fluorine-containing ether compound having a skeleton to which two perfluoropolyether chains are bonded via a divalent connecting group formed by bonding methylene groups (-CH2-) to both ends of a glycerol structure (-O-CH2-CH(OH)-CH2-O-), and end groups having polar groups are bonded to both ends via methylene groups.

[0007] Patent Documents 3 and 4 disclose a fluorine-containing ether compound comprising a methylene group and a group (-CH(OH)-) in which one hydrogen atom of the methylene group is substituted by a hydroxyl group, having a skeleton in which two perfluoropolyether chains are bonded via a divalent connecting group containing two hydroxyl groups, and having end groups of organic groups containing polar groups bonded to both ends thereof via methylene groups.

[0008] Patent Document 5 discloses a fluorine-containing ether compound having a skeleton formed by three perfluoropolyether chains bonded to a methylene group via a glycerol structure, and polar group-containing terminal groups bonded to both sides of the skeleton via methylene groups.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: U.S. Patent No. 10540997 Specification (B)

[0012] Patent document 2: International Publication No. 2021 / 251335 (A).

[0013] Patent Document 3: Japanese Patent No. 5743438 (B)

[0014] Patent Document 4: Japanese Patent No. 6804981 (B)

[0015] Patent document 5: International Publication No. 2022 / 215726 (A). Summary of the invention

[0016] Problems to be solved by the invention

[0017] In the face of the large capacity of magnetic recording and reproducing devices, magnetic recording media suitable for high recording density are being developed. In recent years, in order to improve the recording density of magnetic recording media, it is necessary to further shorten the distance between the magnetic head and the magnetic layer of the magnetic recording medium and reduce the magnetic spacing (flying height). Therefore, it is necessary to make the thickness of the lubricating layer in the magnetic recording medium thinner.

[0018] However, generally speaking, if the thickness of the lubricating layer is reduced, the corrosion resistance of the magnetic recording medium tends to decrease. In addition, if the floating amount of the magnetic head is reduced, the fluorine-containing ether compound in the lubricating layer may sometimes adhere to the sticking (pickle) situation of the magnetic head.

[0019] 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 corrosion resistance and capable of suppressing adhesion and which is suitable as a material for a lubricant for a magnetic recording medium.

[0020] 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 excellent corrosion resistance and a high adhesion suppressing effect.

[0021] Another object of the present invention is to provide a magnetic recording medium having a lubricating layer containing the fluorinated ether compound of the present invention and having excellent corrosion resistance and a high adhesion suppressing effect.

[0022] Means used to solve problems

[0023] The present invention includes the following aspects.

[0024] [1] A fluorine-containing ether compound characterized by being represented by the following formula (1).

[0025] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ]x -CH2-R 4 (1)

[0026] In formula (1), x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; (x+1) R 2 They may be partially or completely the same, or they may be different; R 3 is a divalent linking group having 1 to 4 polar groups; when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms; R 1 and R 4 Can be the same or different; R 1 and R 4 At least one of them is a terminal group represented by the following formula (2).

[0027] -OX-CH(OH)-CH2OH (2)

[0028] In formula (2), X is a divalent organic group having 2 to 30 carbon atoms which may contain at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms, and X contains at least one carbon atom which is not bonded to either the polar group or the ether oxygen atom.

[0029] [2] The fluorinated ether compound according to [1], wherein the terminal group represented by the formula (2) is any one of the following formulas (2-1) to (2-7).

[0030]

[0031] In the formula (2-1), a represents an integer of 1 to 8, and b represents an integer of 1 to 7.

[0032] In formula (2-2), c represents an integer of 1 to 7.

[0033] In the formula (2-3), d represents an integer of 1 to 6.

[0034] In formula (2-4), e represents an integer of 1 to 6, and e R a and R b Each independently represents a hydrogen atom or a methyl group.

[0035] In the formula (2-5), f represents an integer of 1 to 6.

[0036] In the formula (2-6), g represents an integer of 1 to 6.

[0037] In formula (2-7), g2 represents an integer of 1 to 6.

[0038] [3] The fluorinated ether compound according to [1] or [2], wherein R in the formula (1) 1 and R 4 Each is independently a terminal group represented by the above formula (2).

[0039] [4] The fluorinated ether compound according to any one of [1] to [3], wherein R in the formula (1) 1 and R 4 same.

[0040] [5] The fluorinated ether compound according to [1] or [2], wherein R in the formula (1) 1 and R 4 One of them is a terminal group represented by the above formula (2), and the other is a terminal group represented by the following formula (3) which does not belong to the formula (2).

[0041]

[0042] In formula (3), l represents an integer of 1 to 3; l m each independently represents an integer of 1 to 6; l n each independently represents an integer of 1 to 6; in one repeating unit, at least one of m and n is 1; B represents an alkyl group which may have only one polar group, an organic group containing a carbon-carbon unsaturated bond, or a hydrogen atom.

[0043] [6] The fluorinated ether compound according to [1], [2] or [5], wherein R in the formula (1) 1 and R 4 One of them is a terminal group represented by the above formula (2), and the other is a terminal group represented by the following formula (3-1) or (3-2).

[0044]

[0045] In formula (3-1), p represents an integer of 0 to 3; q represents an integer of 0 to 2; r represents an integer of 0 to 5; the total value of p and r is 1 to 5; D represents a polar group, a vinyl group, an ethynyl group, or an aromatic group which may have a substituent.

[0046] In the formula (3-2), s represents an integer of 0-2, and t represents an integer of 1-5.

[0047] [7] The fluorinated ether compound according to any one of [1] to [6], wherein the x R in the formula (1) 3 Each independently represents a divalent linking group having 1 to 3 hydroxyl groups, oxygen atoms at both ends bonded to adjacent methylene groups, and 3 to 50 carbon atoms.

[0048] [8] The fluorinated ether compound according to any one of [1] to [7], wherein the x R in the formula (1) 3 Each independently represents any one selected from the group consisting of linking groups represented by the following formulae (4-1) to (4-6).

[0049]

[0050] In formula (4-1), u1 represents an integer of 0 to 6, and u2 represents an integer of 0 to 6; wherein at least one of u1 and u2 is 0; the oxygen atom at the left terminal of formula (4-1) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

[0051] In formula (4-2), v represents an integer of 1 to 2, and the oxygen atom at the left terminal of formula (4-2) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

[0052] In formula (4-3), w represents an integer of 0 to 6, and the oxygen atom at the left terminal of formula (4-3) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

[0053] In formula (4-4), x1 represents an integer of 0 to 5, and x2 represents an integer of 0 to 5; wherein at least one of x1 and x2 is an integer of 1 to 5; the oxygen atom at the left terminal of formula (4-4) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

[0054] In formula (4-5), y1 represents an integer of 1 to 5, y2 represents an integer of 1 to 5; the oxygen atom at the left terminal of formula (4-5) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

[0055] In formula (4-6), z represents an integer of 1 to 6, and z R c and R d Each independently represents a hydrogen atom, a fluorine atom or a methyl group; the oxygen atom at the left terminal of formula (4-6) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

[0056] [9] The fluorinated ether compound according to any one of [1] to [8], wherein R in the formula (1) 1 With polar groups, R 4 With polar groups and x R 3 The total number of polar groups is 6 to 12.

[0057]

[10] The fluorinated ether compound according to any one of [1] to [9], wherein the (x+1)th R in the formula (1) 2 Each is independently a perfluoropolyether chain represented by the following formula (5).

[0058] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(5)

[0059] In formula (5), w2, w3, w4, and w5 represent the average degree of polymerization, 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 the average values ​​of the number of CF2, and each independently represents 1 to 3; the arrangement order of the repeating units (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) in formula (5) is not particularly limited.

[0060]

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

[10] , 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 (5-1) to (5-4).

[0061] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(5-1)

[0062] In formula (5-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20;

[0063] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(5-2)

[0064] In formula (5-2), j represents the average degree of polymerization and is 1 to 15;

[0065] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(5-3)

[0066] In formula (5-3), k represents the average degree of polymerization and is 1 to 10;

[0067] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(5-4)

[0068] In formula (5-4), 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 groups, and each independently represents 1 to 2.

[0069]

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

[11] , which has a number average molecular weight in the range of 500 to 10,000.

[0070]

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

[12] .

[0071]

[14] A magnetic recording medium comprising at least a magnetic layer, a protective layer, and a lubricating layer provided in this order on a substrate, wherein the lubricating layer comprises the fluorine-containing ether compound described in any one of [1] to

[12] .

[0072]

[15] The magnetic recording medium according to

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

[0073] Effects of the Invention

[0074] Since the fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), it is suitable as a material for a lubricant for a magnetic recording medium.

[0075] The lubricant for a magnetic recording medium of the present invention contains the fluorine-containing ether compound of the present invention, and thus can form a lubricating layer having excellent corrosion resistance and a high adhesion suppressing effect.

[0076] The magnetic recording medium of the present invention has a lubricating layer comprising a fluorinated ether compound of the present invention. Therefore, the magnetic recording medium of the present invention has good corrosion resistance, good adhesion suppression effect, and excellent reliability and durability. In addition, since the magnetic recording medium of the present invention has a lubricating layer with good corrosion resistance and suppressed adhesion, the thickness of the lubricating layer can be reduced, and the floating amount of the magnetic head can be further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention. DETAILED DESCRIPTION

[0078] The present inventors have conducted intensive studies to solve the above-mentioned problems as follows.

[0079] Conventionally, a fluorine-containing ether compound having a polar group such as a hydroxyl group is preferably used as a material of a lubricant for a magnetic recording medium (hereinafter, sometimes simply referred to as a "lubricant") applied to the surface of the protective layer.

[0080] As the fluorinated ether compound having a polar group, there is a fluorinated ether compound having a terminal group having a plurality of polar groups arranged at the end of the chain structure. In addition, as the fluorinated ether compound, there is a fluorinated ether compound having a plurality of perfluoropolyether chains and a connecting group having a polar group arranged between adjacent perfluoropolyether chains.

[0081] However, when a thin lubricating layer is formed on a protective layer using a conventional fluorinated ether compound having a polar group, it is difficult to realize a lubricating layer having good corrosion resistance and a high adhesion suppressing effect as described below.

[0082] That is, the polar groups in the fluorinated ether compound are combined with the active points on the protective layer, so that the adhesion of the lubricating layer to the protective layer is improved. If the adhesion of the lubricating layer to the protective layer is insufficient, the coating state of the lubricating layer to the protective layer becomes insufficient, and the corrosive water becomes easy to enter the protective layer, and sufficient corrosion resistance cannot be obtained. In addition, if the adhesion of the lubricating layer to the protective layer is insufficient, the lubricating layer floating from the protective layer may sometimes collide with the magnetic head and adhere.

[0083] In addition, the polar groups in the fluorinated ether compound not only bind to the active points on the protective layer and participate in the interaction with the protective layer, but also participate in the intramolecular and intermolecular interactions. If the polar groups participating in the intermolecular interactions between the fluorinated ether compound molecules are insufficient, the fluorinated ether compound in the lubricating layer is easy to move from the protective layer to the magnetic head, and adhesion is easy to occur.

[0084] Therefore, the fluorinated ether compound needs to contain sufficient polar groups that participate in the interaction with the protective layer and the polar groups that participate in the interaction between molecules so that a lubricating layer with good corrosion resistance and suppressed adhesion can be formed. However, if the number of polar groups in the fluorinated ether compound is increased, the hydrophobicity of the lubricating layer containing it decreases, so sufficient corrosion resistance cannot be obtained.

[0085] Therefore, the present inventors have repeatedly conducted in-depth studies focusing on the polarity strength of polar groups contained in fluorinated ether compounds and the interaction of polar groups. As a result, it was found that at least a portion of the polar groups in the fluorinated ether compound can be hydroxyl groups of a 1,2-diol structure disposed at the end of the perfluoropolyether chain. In this case, as shown below, the reduction in hydrophobicity caused by the hydroxyl groups contained in the 1,2-diol structure can be suppressed, and hydroxyl groups that can interact with the protective layer and hydroxyl groups that can participate in intermolecular interactions can be ensured.

[0086] In the 1,2-diol structure (-CH(OH)-CH2OH), the carbon atoms to which the hydroxyl groups are bonded are bonded to each other, so the distance between the hydroxyl groups is close, which easily causes steric repulsion and electrostatic repulsion between the hydroxyl groups. As a result, the two hydroxyl groups contained in the 1,2-diol structure are in the reverse conformation relative to the carbon atoms to which the 1,2-diol structure is bonded. Therefore, the dipole moments generated by the two hydroxyl groups contained in the 1,2-diol structure cancel each other out, which can suppress the increase in the polarity of the entire fluorinated ether compound molecule.

[0087] In addition, the distance between the active points on the protective layer is sufficiently large compared to the distance between the hydroxyl groups contained in the 1,2-diol structure. Moreover, the two hydroxyl groups contained in the 1,2-diol structure are in an inverted conformation relative to the carbon atom to which the 1,2-diol structure is bonded. Therefore, the two hydroxyl groups contained in the 1,2-diol structure will not form a direction to approach the protective layer at the same time, and only one of the two hydroxyl groups can interact with the active point on the protective layer. Therefore, the other of the two hydroxyl groups can participate in the intermolecular interaction between the fluorinated ether compounds.

[0088] It should be noted that, in the past, in order to improve the adhesion with the protective layer, the structure of the fluorinated ether compound used in the lubricant was studied to form a configuration that allows as many polar groups in the compound as possible to interact easily with the active points on the protective layer. Therefore, by bonding the carbon atoms to which the hydroxyl groups are bonded to each other, there is a tendency to avoid the structure in which the orientations of adjacent hydroxyl groups on the protective layer are in opposite orientations.

[0089] However, the inventors of the present invention have ensured that polar groups that can participate in the intermolecular interaction between the fluorinated ether compounds are obtained by intentionally making some of the polar groups in the fluorinated ether compound hydroxyl groups of a 1,2-diol structure. Based on this, it is believed that the number of polar groups that can interact with the active points on the protective layer can be adjusted as needed.

[0090] Furthermore, the present inventors have repeatedly studied fluorinated ether compounds having a 1,2-diol structure at one or both ends of a perfluoropolyether chain in order to improve the corrosion resistance of a lubricating layer containing the fluorinated ether compound and suppress adhesion.

[0091] As a result, it was found that any fluorinated ether compound having two or three perfluoropolyether chains, a skeleton having a divalent linking group having 1 to 4 polar groups arranged between adjacent perfluoropolyether chains, end groups having 1 to 4 polar groups and 1 to 50 carbon atoms arranged at both ends of the skeleton, at least one of the two end groups being an end group represented by formula (2) containing at least one carbon atom not bonded to either the polar group or the ether oxygen atom and having a 1,2-diol structure, can be used. This led to the present invention.

[0092] In such a fluorinated ether compound, the number of polar groups is appropriate, and some of the polar groups are hydroxyl groups of a 1,2-diol structure arranged at the end of the perfluoropolyether chain. Therefore, the reduction in hydrophobicity caused by the polar groups can be suppressed, and the polar groups that can interact with the protective layer and the polar groups that can participate in the interaction between molecules can be fully ensured.

[0093] Moreover, the terminal group represented by formula (2) disposed at at least one end contains at least one carbon atom that is not bonded to either the polar group or the ether oxygen atom. The affinity of this carbon atom to water is extremely low, and therefore strongly hinders the interaction between the fluorinated ether compound molecule and water. Therefore, even if a plurality of polar groups are contained in the fluorinated ether compound, sufficient hydrophobicity can be obtained. In addition, since the movement of the above-mentioned carbon atoms is suppressed, appropriate rigidity is brought to the fluorinated ether compound molecule, the intramolecular interaction between the polar groups is suppressed, and the polar groups are easily involved in the intermolecular interaction between the fluorinated ether compounds.

[0094] Furthermore, in the above-mentioned fluorine-containing ether compound, a divalent linking group containing 1 to 4 polar groups is bonded between 2 or 3 perfluoropolyether chains. The distance between the divalent linking group and the adjacent end group sandwiching the perfluoropolyether chain, and the distance between the divalent linking group and other adjacent divalent linking groups sandwiching the perfluoropolyether chain in the case of three perfluoropolyether chains, are all appropriately achieved due to the perfluoropolyether chain. Therefore, the interaction between the polar group possessed by the divalent linking group and the protective layer is not easily hindered by the polar group possessed by the adjacent end group or other adjacent divalent linking groups, and can participate in the interaction with the protective layer.

[0095] In this way, the above-mentioned fluorinated ether compound can ensure the number of polar groups participating in the interaction with the protective layer while maintaining low polarity and having sufficient hydrophobicity. Therefore, the lubricant containing it is not easy to introduce water that causes corrosion, and has excellent corrosion resistance. Moreover, the above-mentioned fluorinated ether compound is prone to produce polar groups that neither participate in the interaction with the protective layer nor participate in the interaction within the molecule, and the polar groups are prone to form intermolecular interactions. Therefore, the fluorinated ether compound in the lubricating layer is difficult to move from the protective layer to the magnetic head, which can inhibit adhesion.

[0096] In contrast, for example, when the end group arranged at at least one end does not include a carbon atom that is not bonded to either the polar group or the ether oxygen atom, or when the fluorinated ether compound is too soft, the polar groups contained in the fluorinated ether compound easily form intramolecular interactions, and thus the polar groups are less likely to participate in intermolecular interactions.

[0097] Furthermore, for example, when the plurality of polar groups contained in the fluorinated ether compound are all arranged so that the distances between adjacent polar groups are sufficiently separated, all polar groups are likely to participate in the interaction with the protective layer, and the interaction between the fluorinated ether compounds due to the polar groups cannot be sufficiently obtained.

[0098] In addition, for example, in the case of a structure in which there is only one perfluoropolyether chain and a divalent connecting group having a polar group is arranged between adjacent perfluoropolyether chains, the central part of the chain structure of the fluorinated ether compound cannot be fully adsorbed on the protective layer. Therefore, the coating state of the lubricating layer on the protective layer becomes insufficient, causing corrosive water to easily enter the protective layer, and sufficient corrosion resistance cannot be obtained. In addition, the lubricating layer is likely to float from the protective layer, and adhesion caused by the collision of the lubricating layer floating from the protective layer with the magnetic head is likely to occur.

[0099] Furthermore, the present inventors have confirmed that by using a lubricant containing the above-mentioned fluorinated ether compound, a lubricating layer having excellent corrosion resistance and a high adhesion suppressing effect can be formed even if the thickness is reduced, and thus conceived the present invention.

[0100] The fluorine-containing ether compound, the lubricant for a magnetic recording medium, and the magnetic recording medium of the present invention are described in detail below. It should be noted that the present invention is not limited to the embodiments described below.

[0101] [Fluorinated ether compounds]

[0102] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

[0103] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ]x-CH2-R 4 (1)

[0104] In formula (1), x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; (x+1) R 2 They may be partially or completely the same, or they may be different; R 3 is a divalent linking group having 1 to 4 polar groups; when x is 2, the two R 3 Can be the same or different; R 1and R 4 is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms; R 1 and R 4 Can be the same or different; R 1 and R 4 At least one of them is a terminal group represented by the following formula (2).

[0105] -OX-CH(OH)-CH2OH(2)

[0106] In formula (2), X is a divalent organic group having 2 to 30 carbon atoms which may contain at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms, and X contains at least one carbon atom which is not bonded to either the polar group or the ether oxygen atom.

[0107] The fluorine-containing ether compound of this embodiment is represented by formula (1) and has R 3 The divalent connecting group represented by R 2 A skeleton in which two or three perfluoropolyether chains (hereinafter sometimes referred to as PFPE chains) are connected via methylene groups. At one end of the skeleton, R 1 The other end of the skeleton is bonded with R 4 Indicates the end group.

[0108] In the fluorine-containing ether compound represented by formula (1), x is 1 or 2, R 2 The number of PFPE chains (x+1) represented by formula (1) is 2 or 3. Therefore, unlike the compound having 1 PFPE chain, in the fluorinated ether compound represented by formula (1), the adjacent R 2 R as a divalent linking group having 1 to 4 polar groups is arranged between 3 . Thus, the fluorinated ether compound represented by formula (1) can form a lubricating layer that has excellent adhesion to the protective layer and is less likely to corrode and adhere to the magnetic recording medium, compared to, for example, a compound having 1 PFPE chain. Moreover, the fluorinated ether compound represented by formula (1) can suppress the molecules from becoming too large and can move freely, compared to a compound having 4 or more PFPE chains. Thus, the fluorinated ether compound represented by formula (1) can easily wet and spread on the protective layer, compared to a compound having 4 or more PFPE chains, and can form a lubricating layer with a thin and uniform film thickness.

[0109] In the fluorinated ether compound represented by formula (1), R 1 , R 3 and R 4 Each has 1 to 4 polar groups. 1 The polar groups contained, R 4 The number of polar groups and x R 3The total number of polar groups contained is preferably 6-12, more preferably 7-10, most preferably 7-8.

[0110] If the total number of the above-mentioned polar groups is more than 6, the interaction between the polar groups and the protective layer of the fluorinated ether compound can be effectively obtained. As a result, a fluorinated ether compound can form a lubricating layer with good adhesion to the protective layer. Therefore, a lubricating layer with better adhesion resistance can be obtained. In addition, if the total number of the above-mentioned polar groups is less than 12, it is possible to prevent the polarity of the fluorinated ether compound from being too high and introducing water that causes corrosion. Therefore, a lubricating layer with better corrosion resistance can be formed.

[0111] (R 1 and R 4 The end group represented by

[0112] R 1 and R 4 It is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms. 1 and R 4 They can be the same or different. 1 and R 4 At least one of them is a terminal group represented by the above formula (2).

[0113] In R 1 and R 4 When one of the groups is a terminal group not belonging to the formula (2), R 1 and R 4 The number of polar groups contained in the terminal groups not belonging to formula (2) is 1 or more. In addition, the terminal groups represented by formula (2) contain at least two hydroxyl groups of the 1,2-diol structure and have two or more polar groups. Therefore, when a lubricant containing a fluorinated ether compound represented by formula (1) is used to form a lubricating layer on the protective layer, regardless of whether R 1 and R 4 When one of the groups is a terminal group represented by formula (2), R 1 and R 4 When both are terminal groups represented by formula (2), R 1 and R 4 The polar groups contained can be polar groups that can interact with the protective layer and polar groups that can participate in intermolecular interactions. As a result, the lubricating layer containing the fluorinated ether compound represented by formula (1) has good corrosion resistance and a good adhesion suppression effect.

[0114] Whether in R 1 and R 4 When both of them are terminal groups represented by formula (2), 1 and R 4When one of the groups is a terminal group not belonging to formula (2), R 1 and R 4 The number of polar groups contained is preferably 2 or more. 1 and R 4 If the number of polar groups contained is 2 or more, the number of polar groups that can interact with the protective layer and the number of polar groups that can participate in intermolecular interactions increase, thereby becoming a fluorine-containing ether compound that can form a lubricating layer with further improved corrosion resistance and good adhesion inhibition effect.

[0115] In addition, R 1 and R 4 The number of polar groups contained is 4 or less. Therefore, in the lubricating layer containing the fluorine-containing ether compound, R 1 and R 4 The polar groups of the terminal groups represented by R can be prevented from agglomerating into a mass, causing the lubricating layer to lose its smoothness, and preventing the lubricating layer from colliding with the magnetic head. 1 and R 4 The number of polar groups contained is less than 4, so in R 1 and R 4 In the lubricating layer, it is difficult to generate polar groups that do not participate in the interaction with the active points on the protective layer or the interaction with the polar groups contained in other fluorinated ether compounds present in the lubricating layer. As a result, it is possible to prevent the R 1 and R 4 If polar groups not participating in these interactions are present in the fluorine-containing ether compound, the hydrophilicity of the fluorine-containing ether compound becomes too high, thereby introducing water that causes corrosion in the magnetic recording medium having a lubricating layer containing it. 1 and R 4 If the number of polar groups contained is 4 or less, the fluorine-containing ether compound can form a lubricating layer having excellent corrosion resistance and adhesion inhibition effects. 1 and R 4 The number of polar groups contained is preferably 3 or less.

[0116] R in formula (1) 1 and R 4 The total number of polar groups possessed is 3 or more, more preferably 4 or more. Since the total number of polar groups is 3 or more, 1 and R 4The polar groups contained can obtain polar groups that can interact with the protective layer and polar groups that can participate in the interaction between molecules. As a result, the lubricating layer containing the fluorinated ether compound represented by formula (1) has excellent adhesion with the protective layer, good corrosion resistance, and good adhesion inhibition effect. R in formula (1) 1 and R 4 The total number of polar groups is preferably 6 or less. If the total number of polar groups is 6 or less, it is possible to more effectively prevent the fluorinated ether compound from having excessively high polarity and from introducing water that causes corrosion into a magnetic recording medium having a lubricating layer containing the fluorinated ether compound.

[0117] R 1 and R 4 When one of the two is an end group not belonging to formula (2), the polar group contained in the end group not belonging to formula (2), and the polar group that X in formula (2) may contain are preferably selected from hydroxyl (-OH), carboxyl (-COOH), formyl (-(C=O)H), carbonyl (-(C=O)R 7 , R 7 is an organic group), a sulfone group (-SO3H), a cyano group (-CN), and a group having an amide bond (-NR 8 COR 9 or-CONR 10 R 11 , R 8 , R 9 , R 10 and R 11 are each independently a hydrogen atom or an organic group), an amino group (-NR 12 R 13 , R 12 and R 13 Each independently is a hydrogen atom or an organic group). As a group having an amide bond, as shown in the above formula, it includes both a group bonded to the carbon atom constituting the amide bond (for example, a formamide group (-C(=O)NH2)) and a group bonded to the nitrogen atom constituting the amide bond (for example, an acetamide group (-NHC(=O)CH3)). In the group having an amide bond, the above R 8 With R 9 can be bonded to each other to form a ring, the above R 10 With R 11 The above R in the group having an amide bond may be bonded to each other to form a ring. 8 , R 9 , R 10 and R 11 Preferably, they are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group.

[0118] The "polar group" in this specification does not include a halogenated group (-F, -Cl, -Br, etc.) or an ether bond (-O-).

[0119] R 1 and R 4 The polar group contained in the terminal group not belonging to formula (2) when one of the terminals is not belonging to formula (2), and the polar group that X in formula (2) may contain preferably contains at least one polar group selected from hydroxyl, cyano, and a group having an amide bond. This is because hydroxyl, cyano, and a group having an amide bond are chemically stable, and the lubricating layer containing the fluorine-containing ether compound having these polar groups will not deteriorate for a long time. In addition, the acidity of hydroxyl, cyano, and a group having an amide bond is not too high, and it is not easy to corrode the substrate.

[0120] In R 1 and R 4 When one of the groups is a terminal group not belonging to the formula (2), the terminal group not belonging to the formula (2) preferably contains at least one hydroxyl group. This is because the coating state of the protective layer with the fluorinated ether compound becomes more uniform.

[0121] Whether in R 1 and R 4 In the case where one of the two is a terminal group represented by formula (2), 1 and R 4 When both are terminal groups represented by formula (2), R 1 The polar groups and R 4 The polar groups possessed are more preferably hydroxyl groups, because the coating state of the protective layer with the fluorine-containing ether compound becomes more uniform.

[0122] R 1 and R 4 When one of them is a terminal group not belonging to formula (2), the polar group contained in the terminal group not belonging to formula (2) and the polar group that X in formula (2) may contain may be partially or entirely the same or may be different.

[0123] In addition, R 1 The number of polar groups and R 4 The number of polar groups they have may be the same or different. 1 The number of polar groups and R 4 The numbers of polar groups possessed are preferably the same in order to make the coating state of the protective layer with the fluorinated ether compound more uniform and to form a lubricating layer having better adhesion.

[0124] In R 1 and R 4 When one of the groups is a terminal group not belonging to formula (2), R 1and R 4 The number of carbon atoms contained in the terminal group not belonging to formula (2) is one or more. In addition, the terminal group represented by formula (2) contains at least two carbon atoms contained in the 1,2-diol structure and two or more carbon atoms contained in X, and has a total of four or more carbon atoms. 1 and R 4 The number of carbon atoms in the terminal group represented by R is one or more, so the hydrophobicity of the terminal group can be ensured, water that causes corrosion can be prevented from being attracted to the lubricating layer, and a lubricating layer with good corrosion resistance can be formed. 1 and R 4 When one of the groups is a terminal group not belonging to formula (2), R 1 and R 4 The number of carbon atoms contained in the terminal groups not belonging to the formula (2) is preferably 3 or more, more preferably 4 or more.

[0125] In R 1 and R 4 When one of the groups is a terminal group not belonging to formula (2), R 1 and R 4 The number of carbon atoms contained in the terminal group not belonging to formula (2) is 50 or less. In addition, the terminal group represented by formula (2) contains 2 carbon atoms of the 1,2-diol structure and 30 or less carbon atoms of X, and has a total of 32 or less carbon atoms. 1 and R 4 The number of carbon atoms of the terminal groups represented is 50 or less, so the terminal groups form a soft structure, and the adhesion between the lubricating layer containing the fluorinated ether compound and the protective layer becomes good. As a result, a lubricating layer capable of suppressing adhesion can be formed. 1 and R 4 The number of carbon atoms of each of the terminal groups represented is preferably 20 or less, more preferably 15 or less.

[0126] (Terminal group represented by formula (2))

[0127] R 1 and R 4 At least one of them is a terminal group represented by the following formula (2).

[0128] -OX-CH(OH)-CH2OH(2)

[0129] In formula (2), X is a divalent organic group having 2 to 30 carbon atoms which may contain at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms, and X contains at least one carbon atom which is not bonded to either the polar group or the ether oxygen atom.

[0130] The terminal group represented by formula (2) has a bond to R 2The oxygen atom on the methylene group (-CH2-) bonded to the end of the terminal group represented by formula (2) forms an ether bond (-O-) with the atoms bonded to both sides thereof. The ether bond imparts moderate softness to the fluorinated ether compound represented by formula (1), thereby increasing the affinity of the polar group possessed by the terminal group represented by formula (2) with the protective layer. Thus, the fluorinated ether compound represented by formula (1) can form a lubricating layer having excellent adhesion to the protective layer.

[0131] The terminal group represented by formula (2) includes a 1,2-diol structure. As described above, it is possible to suppress a decrease in hydrophobicity due to hydroxyl groups contained in the 1,2-diol structure while ensuring hydroxyl groups that can interact with the protective layer and that can participate in intermolecular interactions.

[0132] Therefore, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) has low affinity with water, is not easy to introduce water that causes corrosion, and has excellent corrosion resistance. In addition, since the polar groups that do not participate in the interaction with the protective layer are easy to form intermolecular interactions, the fluorine-containing ether compound in the lubricating layer is not easy to move from the protective layer to the magnetic head, thereby inhibiting adhesion.

[0133] X in the terminal group represented by formula (2) contains at least one carbon atom that is not bonded to either the polar group or the ether oxygen atom. Therefore, the lubricating layer containing the fluorinated ether compound represented by formula (1) has a low affinity for water. Furthermore, the above-mentioned carbon atoms bring moderate rigidity to the fluorinated ether compound molecules, inhibit the intramolecular interaction between the polar groups, and make it easy for the polar groups to participate in the intermolecular interaction between the fluorinated ether compounds. Therefore, the above-mentioned carbon atoms contained in X in the terminal group represented by formula (2) contribute to the formation of a lubricating layer with good corrosion resistance and good adhesion inhibition effect.

[0134] On the other hand, in formula (2), when -OX- is replaced by -OCH2CH(OH)CH2OCH2-, for example, all carbon atoms in the structure are bonded to polar groups or ether oxygen atoms. The lubricating layer containing such a fluorinated ether compound has a high affinity for water and poor corrosion resistance compared to the lubricating layer containing the fluorinated ether compound represented by formula (1), and has insufficient polar groups that can participate in intermolecular interactions, so it has poor adhesion resistance.

[0135] The number of carbon atoms of the organic group represented by X in formula (2) is 2 or more, thus bringing about moderate rigidity, suppressing the intramolecular interaction between polar groups, making it easy for the polar groups to participate in the intermolecular interaction between the fluorinated ether compounds, and at the same time hindering the interaction with water, thereby improving the hydrophobicity. In addition, since the number of carbon atoms of the organic group represented by X is 30 or less, it is possible to suppress the end group represented by formula (2) from becoming too large, hindering the movement of the polar groups contained in the fluorinated ether compounds, and hindering the interaction between the polar groups and the protective layer. The number of carbon atoms of the organic group represented by X is preferably 2 to 15, and more preferably 3 to 10.

[0136] The organic group represented by X contains at least one carbon atom that is not bonded to either the polar group or the ether oxygen atom. Examples of the carbon atom that is not bonded to either the polar group or the ether oxygen atom include a methylene group, a methine group, or a carbon atom of a group formed by fluorination of these groups that are not bonded to either the polar group or the ether oxygen atom. It should be noted that, as described above, a fluorine group is not included in the above-mentioned polar group.

[0137] When the organic group represented by X is a polar group containing carbon atoms (e.g., carboxyl group, formyl group, carbonyl group, cyano group, group having an amide bond), the carbon atoms contained in the polar group are not included in the “carbon atoms not bonded to either the polar group or the ether oxygen atom”.

[0138] The number of carbon atoms that are not bonded to polar groups and ether oxygen atoms may be 1 or more, for example, it may be set to 1 to 6, or 1 to 4. If the number of carbon atoms that are not bonded to polar groups and ether oxygen atoms is 1 or more, the hydrophobicity of the lubricating layer containing the fluorine-containing ether compound becomes good. In addition, if the number of carbon atoms that are not bonded to polar groups and ether oxygen atoms is 6 or less, the ratio of the number of carbon atoms to the number of polar groups is appropriate, the polarity of the molecule is appropriate, and the ratio of the number of carbon atoms to the number of ether oxygen atoms becomes appropriate, and a fluorine-containing ether compound with appropriate molecular flexibility is formed. In addition, in the case of containing a plurality of carbon atoms that are not bonded to polar groups and ether oxygen atoms, the carbon atoms that are not bonded to polar groups and ether oxygen atoms can be bonded to each other. In this case, the fluorine-containing ether compound molecule becomes more rigid, the intramolecular interaction between polar groups is suppressed, and the polar groups are more likely to participate in the intermolecular interaction between fluorine-containing ether compounds.

[0139] The organic group represented by X in formula (2) may contain 1 or 2 polar groups. In the case where the organic group represented by X in formula (2) contains 1 or 2 polar groups, the adhesion of the fluorinated ether compound represented by formula (1) to the protective layer is improved, and it is easy to form a lubricating layer that can obtain a sufficient coating state even if the thickness is reduced. In the case where the organic group represented by X in formula (2) contains a polar group, the number of polar groups is preferably one. This is because it is possible to suppress the excessive hydrophilicity of the fluorinated ether compound represented by formula (1) from inducing water that causes corrosion.

[0140] When the organic group represented by X in formula (2) has a polar group, the polar group is preferably a polar group selected from a hydroxyl group, a cyano group and a group having an amide bond as described above.

[0141] The organic group represented by X in formula (2) may contain 1 to 3 ether bonds. When the organic group represented by X in formula (2) contains an ether bond, the oxygen atom forming the ether bond imparts moderate softness to the fluorinated ether compound represented by formula (1), thereby increasing the affinity between the polar group and the protective layer. When the organic group represented by X in formula (2) contains an ether bond, the number of ether bonds is preferably 1 or 2. This is to prevent the fluorinated ether compound represented by formula (1) from becoming too soft and easily generating polar groups that participate in intramolecular interactions.

[0142] The organic group represented by X in formula (2) may be partially fluorinated. When the organic group represented by X in formula (2) is partially fluorinated, the hydrophilicity of the organic group represented by X in formula (2) is reduced compared to the case where the organic group represented by X is not fluorinated. As a result, a fluorine-containing ether compound is formed that can suppress the generation of water that causes corrosion and form a lubricating layer with better corrosion resistance.

[0143] The organic group represented by X in formula (2) is preferably a non-cyclic organic group. When the organic group represented by X is non-cyclic, the organic group represented by X will not become too large compared with the case where X is an organic group having a cyclic structure. Therefore, the organic group represented by X can be suppressed from hindering the movement of the polar group contained in the fluorinated ether compound and hindering the interaction between the polar group and the protective layer. The non-cyclic organic group can be a straight chain or a branched chain.

[0144] The organic group represented by X in formula (2) preferably does not contain an unsaturated carbon-carbon bond. In the case where the organic group represented by X does not contain an unsaturated carbon-carbon bond, compared with the case where X contains an unsaturated carbon-carbon bond, the molecular orientation contained in the organic group represented by X is restricted, which can inhibit the movement of the polar group contained in the fluorine-containing ether compound and hinder the interaction between the polar group and the protective layer.

[0145] More specifically, the terminal group represented by the formula (2) is preferably a terminal group represented by any one of the following formulae (2-1) to (2-7).

[0146]

[0147] In the formula (2-1), a represents an integer of 1 to 8, and b represents an integer of 1 to 7.

[0148] In formula (2-2), c represents an integer of 1 to 7.

[0149] In the formula (2-3), d represents an integer of 1 to 6.

[0150] In formula (2-4), e represents an integer of 1 to 6, and e R a and R b Each independently represents a hydrogen atom or a methyl group.

[0151] In the formula (2-5), f represents an integer of 1 to 6.

[0152] In the formula (2-6), g represents an integer of 1 to 6.

[0153] In formula (2-7), g2 represents an integer of 1 to 6.

[0154] The terminal group represented by formula (2-1) is a terminal group represented by formula (2) wherein -X- is -CH2-CH(OH)-(CH2) a -O-(CH2) b a represents an integer of 1 to 8, and b represents an integer of 1 to 7.

[0155] The terminal group represented by formula (2-1) has a connecting group formed by bonding b+1 methylene groups between the 1,2-diol structure (-CH(OH)-CH2OH) disposed at the end of formula (2) and the ether oxygen atom forming the ether bond contained in X in formula (2). The connecting group has b carbon atoms that are not bonded to the polar group and the ether oxygen atom. Therefore, the terminal group represented by formula (2-1) has moderate rigidity due to the connecting group composed of b+1 methylene groups, which can inhibit the hydroxyl groups of the terminal group represented by formula (2-1) from forming intramolecular interactions.

[0156] Since b in formula (2-1) is 1 or more, the terminal group represented by formula (2-1) has a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and sufficient hydrophobicity can be obtained. In addition, since b is 7 or less, it is possible to prevent the terminal group represented by formula (2-1) from becoming too large, hindering the movement of the hydroxyl group possessed by the terminal group represented by formula (2-1), and hindering the interaction with the protective layer. b is preferably 1 to 5, and more preferably 1 to 3.

[0157] In addition, the end group represented by formula (2-1) has a connecting group formed by bonding a methylene group between the carbon atom bonded to the secondary hydroxyl group on one side of the perfluoropolyether chain and the ether oxygen atom forming the ether bond. Since a in formula (2-1) is greater than 1, the end group represented by formula (2-1) has sufficient hydrophobicity. In addition, since a is less than 8, the end group represented by formula (2-1) can be prevented from becoming too large, hindering the movement of the hydroxyl group possessed by the end group represented by formula (2-1), and hindering the interaction with the protective layer. a is preferably 1 to 6, and more preferably 1 to 4.

[0158] The sum of a and b of the terminal group represented by formula (2-1) is preferably 9 or less. When the sum of a and b is 9 or less, it is possible to effectively prevent the terminal group represented by formula (2-1) from becoming too large, hindering the movement of the hydroxyl group possessed by the terminal group represented by formula (2-1), and hindering the interaction with the protective layer. The sum of a and b is more preferably 6 or less.

[0159] In addition, the end group represented by formula (2-1) has moderate mobility because X in formula (2) contains an ether bond. Therefore, when only one of the two hydroxyl groups in the 1,2-diol structure in formula (2-1) interacts with the protective layer, the other hydroxyl group is more likely to interact with the polar groups in other fluorinated ether compounds. Therefore, the hydroxyl groups in formula (2-1) can easily form intermolecular interactions. As a result, the lubricating layer containing the fluorinated ether compound having the end group represented by formula (2-1) is difficult to move from the protective layer to the magnetic head, thereby suppressing adhesion.

[0160] The terminal group represented by formula (2-2) is that -X- in formula (2) is -CH2-CH(OH)-CH2-(CH2) c -O-CH2- group. c represents an integer of 1-7.

[0161] The terminal group represented by formula (2-2) has a connecting group formed by bonding c+1 methylene groups between the carbon atom bonded to the secondary hydroxyl group on one side of the perfluoropolyether chain and the ether oxygen atom formed by the ether bond contained in X in formula (2). The connecting group has c carbon atoms that are not bonded to the polar group and the ether oxygen atom. Therefore, the terminal group represented by formula (2-2) has moderate rigidity caused by the connecting group composed of c+1 methylene groups, which can inhibit the hydroxyl groups of the terminal group represented by formula (2-2) from forming intramolecular interactions.

[0162] In addition, since c in formula (2-2) is 1 or more, the terminal group represented by formula (2-2) has a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and sufficient hydrophobicity can be obtained. In addition, since c is 7 or less, it is possible to prevent the terminal group represented by formula (2-2) from becoming too large, hindering the movement of the hydroxyl group possessed by the terminal group represented by formula (2-2), and hindering the interaction with the protective layer. c is preferably 1 to 5, and more preferably 1 to 3.

[0163] In addition, the end group represented by formula (2-2) has high mobility because X in formula (2) contains an ether bond, and the ether oxygen atom forming the ether bond is bonded to the carbon atom bonded to the 1,2-diol structure (-CH(OH)-CH2OH). Therefore, of the two hydroxyl groups possessed by the 1,2-diol structure in formula (2-2), only one hydroxyl group easily interacts with the protective layer, and the other hydroxyl group easily interacts with polar groups in other fluorinated ether compounds. Therefore, the hydroxyl groups in formula (2-2) can easily form intermolecular interactions. As a result, the lubricating layer containing the fluorinated ether compound having the end group represented by formula (2-2) is difficult to move from the protective layer to the magnetic head, thereby suppressing adhesion.

[0164] The terminal group represented by formula (2-3) is that -X- in formula (2) is -CH2-CH(OH)-(CH2) d -. d represents an integer of 1-6.

[0165] The terminal group represented by formula (2-3) has a connecting group formed by bonding d methylene groups between the 1,2-diol structure (-CH(OH)-CH2OH) and the carbon atom to which the secondary hydroxyl group contained in X in formula (2) is bonded. The connecting group has d carbon atoms that are not bonded to either the polar group or the ether oxygen atom. Therefore, the terminal group represented by formula (2-3) has moderate rigidity due to the connecting group composed of d methylene groups, which can inhibit the hydroxyl groups of the terminal group represented by formula (2-3) from forming intramolecular interactions.

[0166] Since d in formula (2-3) is 1 or more, the terminal group represented by formula (2-3) has a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and sufficient hydrophobicity can be obtained. In addition, since d is 6 or less, the terminal group represented by formula (2-3) can be prevented from becoming too large, hindering the movement of the hydroxyl group possessed by the terminal group represented by formula (2-3), and hindering the interaction with the protective layer. d is preferably 1 to 4, and more preferably 2 to 4.

[0167] In addition, the end group represented by formula (2-3) does not contain an ether bond in which X in formula (2) is a hydrophilic part. Therefore, the end group represented by formula (2-3) has low affinity with water and good hydrophobicity. Thus, the fluorinated ether compound having the end group represented by formula (2-3) is further less likely to introduce water that causes corrosion, and can form a lubricating layer with better corrosion resistance.

[0168] The terminal group represented by formula (2-4) is a terminal group represented by formula (2) wherein -X- is -CH2-CH(OH)-CH2-O-CH2-(CR a R b ) e -CH2-O-CH2- group. e represents an integer from 1 to 6, and e R a and R b Each independently represents a hydrogen atom or a methyl group. That is, the e terminal groups (—CR a R b -) may be any of -CH2-, -CH(CH3)-, and -C(CH3)2-.

[0169] The terminal group represented by formula (2-4) is a group in which X in formula (2) contains two ether bonds, and between the oxygen atoms forming the two ether bonds there is a group (-CR a R b -) connecting group, the group (-CR a R b -) has at least e carbon atoms which are not bonded to either polar groups or ether oxygen atoms.

[0170] Since e in formula (2-4) is 1 or more, the terminal group represented by formula (2-4) has a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and sufficient hydrophobicity can be obtained. In addition, since e is 6 or less, it is possible to prevent the terminal group represented by formula (2-4) from becoming too large, hindering the movement of the hydroxyl group possessed by the terminal group represented by formula (2-4), and hindering the interaction with the protective layer. e is preferably 1 to 4, and more preferably 1 to 2.

[0171] The terminal group represented by formula (2-4) is a terminal group represented by formula (2) when X in formula (2) has a straight-chain structure connecting group between the oxygen atoms forming two ether bonds (in other words, e R a and R b When all R are hydrogen atoms), the linking group having a structure in which a branched chain exists between the above oxygen atoms (in other words, e R a and R bCompared with the case where more than one of the fluorocarbons is a methyl group, the end group represented by formula (2-4) can be inhibited from becoming too large and hindering the movement of the hydroxyl group possessed by the end group represented by formula (2-4). Therefore, for the end group represented by formula (2-4), when X in formula (2) has a connecting group with a straight-chain structure between oxygen atoms that form two ether bonds, only one of the two hydroxyl groups possessed by the 1,2-diol structure in formula (2-4) is easy to interact with the protective layer, and the other hydroxyl group is easy to interact with polar groups in other fluorinated ether compounds. Therefore, the hydroxyl group in formula (2-4) can easily form intermolecular interactions. As a result, the lubricating layer containing the fluorinated ether compound having the end group represented by formula (2-4) is difficult to move from the protective layer to the magnetic head, thereby inhibiting adhesion.

[0172] In the end group represented by formula (2-4), when X in formula (2) has a connecting group having a structure of branched chain between oxygen atoms forming two ether bonds (i.e., including -CH(CH3)- and / or -C(CH3)2-), X becomes a moderately rigid group. Therefore, the hydroxyl groups possessed by the end groups represented by formula (2-4) can be effectively suppressed from forming intramolecular interactions with each other, and the hydroxyl groups in formula (2-4) can easily form intermolecular interactions. Thus, the lubricating layer comprising the fluorinated ether compound represented by the end group of formula (2-4) is not easy to move to the magnetic head from the protective layer, and has excellent adhesion resistance.

[0173] The terminal group represented by formula (2-5) is that -X- in formula (2) is -CH2-CH(OH)-CH2-O-CH2-(CF2) f f represents an integer of 1 to 6.

[0174] The terminal group represented by formula (2-5) has X in formula (2) containing two ether bonds and a linking group between the oxygen atoms forming the two ether bonds, wherein the linking group has f carbon atoms that are not bonded to the polar group and the ether oxygen atom.

[0175] The terminal group represented by formula (2-5) contains a linear perfluoroalkylene chain [-(CF2) f -]. The linear perfluoroalkylene chain having 1 to 6 carbon atoms is excellent in hydrophobicity and reduces the affinity of the lubricating layer containing the fluorinated ether compound to water.

[0176] The terminal group represented by formula (2-5) has a saturated hydrocarbon group (-CH2-(CF2) in formula (2-5)) containing a linear perfluoroalkylene chain having 1 to 6 carbon atoms between the oxygen atoms forming the two ether bonds. f-CH2-). Therefore, the polarity of the fluorinated ether compound molecule as a whole becomes low, and a lubricating layer with good hydrophobicity can be formed. As a result, the lubricating layer containing the fluorinated ether compound having the terminal group represented by formula (2-5) has a low affinity for water that causes corrosion, is not easily introduced with water, and has further improved corrosion resistance.

[0177] Since f in formula (2-5) is 1 or more, the terminal group represented by formula (2-5) has a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and sufficient hydrophobicity can be obtained while being moderately rigid, which can inhibit the hydroxyl groups of the terminal groups represented by formula (2-5) from forming intramolecular interactions with each other. In addition, since f is 6 or less, it is possible to inhibit the terminal group represented by formula (2-5) from becoming too large, hindering the movement of the hydroxyl groups of the terminal groups represented by formula (2-5), and hindering the interaction with the protective layer. f is preferably 1 to 4, and more preferably 2 to 4.

[0178] The terminal group represented by formula (2-6) is -X- in formula (2) is -(CH2) g g represents an integer of 1 to 6.

[0179] The terminal group represented by formula (2-6) has a connecting group formed by g+1 methylene groups bonding between the 1,2-diol structure (-CH(OH)-CH2OH) and the ether oxygen atom at the bonding end. By having this connecting group, the terminal group represented by formula (2-6) has g carbon atoms that are not bonded to the polar group and the ether oxygen atom. Therefore, the terminal group represented by formula (2-6) has moderate rigidity due to the connecting group composed of g+1 methylene groups, which can inhibit the hydroxyl groups of the terminal group represented by formula (2-6) from forming intramolecular interactions.

[0180] Since g in formula (2-6) is 1 or more, the terminal group represented by formula (2-6) has a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and becomes a moderately rigid group, which can inhibit the hydroxyl group of the 1,2-diol structure from forming an intramolecular interaction. In addition, since g in formula (2-6) is 6 or less, it is possible to inhibit the terminal group represented by formula (2-6) from becoming too large and hindering the movement of the hydroxyl group of the 1,2-diol structure and hindering the interaction with the protective layer. g is preferably 1 to 5, and more preferably 1 to 3.

[0181] In addition, the end group represented by formula (2-6) does not contain a polar group and an ether bond in which X in formula (2) is a hydrophilic part. Therefore, the end group represented by formula (2-6) has low affinity with water and good hydrophobicity. Thus, the fluorinated ether compound having the end group represented by formula (2-6) is further less likely to introduce water that causes corrosion, and can form a lubricating layer with better corrosion resistance.

[0182] The terminal group represented by formula (2-7), the organic group represented by X in formula (2) is -(CH2) g2 -CH2-CH(OH)-CH2-O-CH2-. g2 represents an integer of 1 to 6.

[0183] The terminal group represented by formula (2-7) has a glycerol structure (-O-CH2-CH(OH)-CH2OH) at the terminal portion. Since the glycerol structure has high mobility, when one of the two hydroxyl groups at the terminal portion interacts with the protective layer, the other hydroxyl group easily interacts with the polar groups in other fluorinated ether compounds between molecules. Therefore, the polar groups in the fluorinated ether compounds represented by formula (1) can more easily form intermolecular interactions. As a result, the lubricant containing the fluorinated ether compound represented by formula (1) is not easy to move from the protective layer to the magnetic head, and has excellent adhesion resistance.

[0184] Since g2 in formula (2-7) is 1 or more, formula (2-7) becomes moderately rigid, and the hydroxyl groups in the 1,2-diol structure are less likely to form intramolecular interactions. In addition, since g2 in formula (2-7) is 6 or less, the end groups represented by formula (2-7) do not become too large, which can inhibit the movement of the hydroxyl groups and hinder the interaction with the protective layer. g2 is preferably 1 to 5, and more preferably 1 to 3.

[0185] R in formula (1) 1 and R 4 Each of them may be independently a terminal group represented by formula (2), or may be R 1 and R 4 Only one of them is a terminal group represented by formula (2).

[0186] In the fluorine-containing ether compound represented by formula (1), R 1 With R 4 They can be the same or different. 1 and R 4 This is to form a fluorine-containing ether compound that can be easily and efficiently prepared.

[0187] It should be noted that “R 1 and R 4 The same refers to R 1 The atoms and R contained in 4 The atoms contained in 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-symmetric configuration.

[0188] In the fluorine-containing ether compound represented by formula (1), R 1 With R 4Different, it can be R 1 and R 4 are terminal groups represented by formula (2), and may also be R 1 and R 4 Only one of them is a terminal group represented by formula (2), and the other is a terminal group not belonging to formula (2). As for the terminal group not belonging to formula (2), as described above, it only needs to be a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms.

[0189] (Terminal group represented by formula (3))

[0190] In R 1 and R 4 When one of them is a terminal group represented by formula (2) and the other is a terminal group not belonging to formula (2), the other is preferably a terminal group not belonging to formula (2) represented by the following formula (3).

[0191]

[0192] In formula (3), l represents an integer of 1 to 3, l m each independently represents an integer of 1 to 6, l n each independently represents an integer of 1 to 6, in one repeating unit, at least one of m and n is 1, and B represents an alkyl group which may have only one polar group, an organic group containing a carbon-carbon unsaturated bond, or a hydrogen atom.

[0193] The terminal group represented by formula (3) has a bond to R 2 The oxygen atom on the methylene group (-CH2-) bonded to the end group represented by formula (3) forms an ether bond (-O-) with the atoms bonded to both sides thereof. The ether bond imparts moderate softness to the fluorinated ether compound represented by formula (1), thereby increasing the affinity of the polar group possessed by the end group represented by formula (3) with the protective layer. Thus, the fluorinated ether compound represented by formula (1) can form a lubricating layer having excellent adhesion to the protective layer.

[0194] In formula (3), l is an integer of 1 to 3, preferably an integer of 1 to 2, and most preferably 1. If l in formula (3) is 3 or less, the number of hydroxyl groups of the terminal groups represented by formula (3) is excessive, thereby preventing water that causes corrosion from being attracted to the lubricating layer, and obtaining a lubricating layer with good corrosion resistance.

[0195] When l in formula (3) is 2 or 3, 2 or 3 repeating units (-(CH2) m -CH(OH)-(CH2) n The combination of m and n in (-O-) may be different from each other, or may be partially or entirely the same.

[0196] In the formula (3), each of the 1 m's independently represents an integer of 1 to 6, and each of the 1 n's independently represents an integer of 1 to 6.

[0197] In formula (3), a repeating unit (-(CH2) m -CH(OH)-(CH2) n -O-), at least one of m and n is 1. This is because the mobility of the hydroxyl group in the repeating unit does not decrease due to too many carbon atoms in the alkylene group between the carbon atom to which the hydroxyl group is bonded and the ether oxygen atom.

[0198] In the formula (3), each of the 1 m's is preferably an integer of 1 to 4 independently. In addition, each of the 1 n's is preferably an integer of 1 to 4 independently.

[0199] B in formula (3) represents an alkyl group which may have only one polar group, an organic group containing a carbon-carbon unsaturated bond, or a hydrogen atom.

[0200] When B in the formula (3) is an alkyl group having no polar group, specific examples of B include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.

[0201] When B in formula (3) is an alkyl group having a polar group, the polar group is preferably a group listed as a preferred example of a polar group not included in the terminal group of formula (2). Among the above polar groups, a polar group selected from a hydroxyl group, a cyano group and a group having an amide bond is more preferred.

[0202] In the case where B in the formula (3) is an alkyl group having a polar group, examples of B include 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 2-aminoethyl, 3-aminopropyl, 1-carboxymethyl, 2-carboxyethyl, 3-carboxypropyl, 1-carbonylmethyl, 2-carbonylethyl, 3-carbonylpropyl, 1-acetylmethyl, 2-acetylethyl, 3-acetylpropyl, 2-sulfoethyl, 3-sulfopropyl, 1-cyanomethyl, 2-cyanoethyl, 3-cyanopropyl, 4-cyanobutyl, 2-acetamidoethyl, 3-acetamidopropyl, 4-acetamidobutyl, 1-formamidomethyl, 2-formamidoethyl, 3-formamidopropyl, and 4-formamidobutyl.

[0203] Among the above-mentioned alkyl groups having polar groups, any one of 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 1-cyanomethyl, 2-cyanoethyl, 3-cyanopropyl, 2-acetamidoethyl, 1-formamidomethyl, 2-formamidoethyl, and 3-formamidopropyl is preferred, and any one of 2-hydroxyethyl, 3-hydroxypropyl, 2-cyanoethyl, 3-cyanopropyl, 2-acetamidoethyl, and 1-formamidomethyl is more preferred.

[0204] When B in formula (3) is an organic group containing a carbon-carbon unsaturated bond, examples of B include organic groups containing at least one selected from aromatic hydrocarbons, unsaturated heterocycles, alkenyl groups, and alkynyl groups.

[0205] In the case where B in the formula (3) is an organic group containing a carbon-carbon unsaturated bond, examples of B include phenyl, methoxyphenyl, fluorophenyl, acetamidophenyl, formamidophenyl, cyanophenyl, naphthyl, phenethyl, methoxyphenethyl, fluorophenethyl, benzyl, methoxybenzyl, naphthylmethyl, methoxynaphthyl, pyrrolyl, pyrazolyl, methylpyrazolylmethyl, imidazolyl, furanyl, furfuryl, oxazolyl, isoxazolyl, thienyl, thienylethyl, thiazole yl, methylthiazolylethyl, isothiazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, indolyl, benzofuranyl, benzothiophenyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzopyrazolyl, benzisoxazolyl, benzisothiazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, phthalazinyl, cinnolinyl, vinyl, allyl, butenyl, propynyl, propargyl, butynyl, methylbutynyl, pentynyl, methylpentynyl, hexynyl and the like.

[0206] Among the organic groups containing carbon-carbon unsaturated bonds, preferably any one of phenyl, methoxyphenyl, acetamidophenyl, formamidophenyl, cyanophenyl, naphthyl, phenethyl, methoxyphenethyl, fluorinated phenethyl, thienylethyl, allyl, butenyl, and propargyl is preferred, and more preferably any one of phenyl, methoxyphenyl, formamidophenyl, allyl, and butenyl is preferred. This is because it has sufficient hydrophobicity and does not become too large to hinder the movement of the hydroxyl group in formula (3), thereby preventing the interaction with the protective layer from being hindered.

[0207] When B in formula (3) is a hydrogen atom, B forms a hydroxyl group together with the oxygen atom in formula (3).

[0208] In R 1 and R 4 When one of them is a terminal group represented by formula (3), it is more preferably a terminal group represented by formula (3-1) or (3-2).

[0209]

[0210] In formula (3-1), p represents an integer of 0 to 3, q ​​represents an integer of 0 to 2, r represents an integer of 0 to 5, the total value of p and r is 1 to 5, and D represents a polar group, a vinyl group, an ethynyl group, or an aryl group which may have a substituent.

[0211] In the formula (3-2), s represents an integer of 0-2, and t represents an integer of 1-5.

[0212] Each polar group contained in the terminal group represented by formula (3-1) and (3-2) is bonded to a different carbon atom. In formula (3-1) and (3-2), the carbon atoms bonded with the polar groups are bonded to each other via a connecting group containing a carbon atom to which the polar groups are not bonded. 1 or R 4 In the fluorine-containing ether compound represented by formula (1) having an end group represented by formula (3-1) or (3-2), the terminal polar group in formula (3-1) or (3-2) and the hydroxyl group adjacent to the terminal polar group can form an orientation capable of being closely attached to the protective layer by means of a connecting group containing a carbon atom that is not bonded to the polar group in formula (3-1) or (3-2). Therefore, a strong interaction with the protective layer can be obtained.

[0213] In R 1 or R 4 In the case of the terminal group represented by formula (3-1) or formula (3-2), the polar groups in the terminal group are less likely to aggregate with each other and are more likely to interact with the protective layer. 1 or R 4 In the case of the terminal group represented by formula (3-1) or (3-2), the terminal portion in the fluorinated ether compound is less likely to float up and the adhesion to the protective layer is less likely to decrease compared to the case of the terminal group in which the carbon atoms to which the polar group is bonded are directly bonded to each other.

[0214] In the terminal group represented by formula (3-1), the connecting group between the carbon atom to which D is bonded in the polar group, vinyl group, ethynyl group, or aryl group which may have a substituent and the carbon atom to which the hydroxyl group adjacent to D is bonded at the terminal contains an oxygen atom forming an ether bond. In formula (3-1), p represents an integer of 0 to 3, q ​​represents an integer of 0 to 2, r represents an integer of 0 to 5, and the total value of p and r is 1 to 5. Therefore, the above-mentioned connecting group has a straight-chain structure composed of 2 to 7 atoms including carbon atoms to which the polar group is not bonded.

[0215] In the end group represented by formula (3-1), the above-mentioned connecting group is a linear structure composed of more than 2 atoms of atoms including an oxygen atom forming an ether bond and a carbon atom not bonded to a polar group, so the distance between D and the hydroxyl adjacent to D is appropriate. Therefore, it is possible to suppress the interaction between D and the hydroxyl adjacent to D in the molecule, and the polar group in the end group represented by formula (3-1) can efficiently fit the protective layer. In addition, since the above-mentioned connecting group is a linear structure composed of more than 2 atoms, even a fluorine-containing ether compound containing an oxygen atom forming an ether bond can become a fluorine-containing ether compound with good hydrophobicity. In addition, the above-mentioned connecting group is a linear structure composed of more than 2 atoms, so even if it contains an oxygen atom forming an ether bond, the mobility of the molecule is appropriate, it is not easy to cause intramolecular aggregation, and it has excellent adhesion to the protective layer.

[0216] In the terminal group represented by formula (3-1), since the above-mentioned connecting group is a straight-chain structure composed of 7 or less atoms including oxygen atoms forming ether bonds and carbon atoms not bonded to polar groups, the adhesion between the lubricating layer containing the fluorine-containing ether compound and the protective layer will not be hindered due to the excessively high hydrophobicity of the connecting group.

[0217] Thus, the lubricating layer containing a fluorinated ether compound having a linear structure in which the connecting group is composed of 2 to 7 carbon atoms containing an unbonded polar group and having an end group represented by formula (3-1) has excellent adhesion to the protective layer, exhibits high corrosion resistance, and has a good adhesion inhibition effect.

[0218] In formula (3-1), the total value of p and r is 1 to 5, preferably 1 to 3. In formula (3-1), the carbon atoms contained in the connecting group arranged between the carbon atoms to which the polar group is bonded prevent the intramolecular interaction between adjacent polar groups from occurring in priority to the interaction between the polar group and the protective layer, thereby improving the adhesion between the polar group in formula (3-1) and the protective layer. On the other hand, when the number of carbon atoms contained in the above-mentioned connecting group is too large, the flexibility of the end group represented by formula (3-1) is reduced, and it is sometimes difficult to evenly cover the protective layer. In the end group represented by formula (3-1), the total value of p and r is 5 or less, so the alkylene chain of the main chain part of formula (3-1) will not be too long. Therefore, due to the rigid alkylene chain length, the flexibility of the terminal part is reduced, which can prevent the interaction with the protective layer from weakening and causing the terminal part to float. p is preferably 0 or 1, and more preferably 0. r is preferably 1 or 2, and more preferably 1.

[0219] D in formula (3-1) represents a polar group, vinyl, ethynyl, or an aryl group which may have a substituent. When D is a polar group, D is preferably a group listed as a preferred example of a polar group contained in the end group not belonging to formula (2). Among the above polar groups, a polar group selected from a hydroxyl group, a cyano group, and a group having an amide bond is more preferably used. When D is an aryl group which may have a substituent, an aryl group which may have a substituent contained in an organic group which can be used when B in the above formula (3) is an organic group containing a carbon-carbon unsaturated bond can be used.

[0220] In formula (3-1), q represents an integer of 0 to 2. The number of polar groups in formula (3-1) is q+2 when D is a polar group, and is q+1 when D is a vinyl group or an ethynyl group. As described above, R 1 and R 4 The number of polar groups contained is preferably 2 or more and 3 or less. Therefore, q in formula (3-1) is preferably 0 or 1 when D is a polar group, and is preferably 1 or 2 when D is a vinyl or ethynyl group. When D is an aryl group which may have a substituent, q is preferably selected so that the number of polar groups in formula (3-1) becomes 2 or 3.

[0221] In the end group represented by 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. As a result, the intramolecular interaction is small and intramolecular aggregation is not likely to occur, so it has excellent adhesion to the protective layer. T in formula (3-2) represents an integer of 1 to 5. Therefore, the above-mentioned connecting group has a straight-chain structure composed of 1 to 5 atoms of carbon atoms containing unbonded hydroxyl groups.

[0222] The linking group contained in formula (3-2) is a linear structure composed of one or more atoms including a carbon atom not bonded to a hydroxyl group, so the distance between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group is appropriate, intramolecular aggregation is unlikely to occur, and the hydrophobicity is good.

[0223] In addition, the above-mentioned connecting group contained in formula (3-2) is a straight-chain structure that does not contain oxygen atoms that form ether bonds and is composed of 5 or less atoms including carbon atoms that are not bonded to hydroxyl groups. Therefore, the hydrophobicity of the connecting group will not be too high to hinder the adhesion to the protective layer, and the impact of the connecting group becoming too large to hinder the movement of hydroxyl groups is also small.

[0224] In addition, in formula (3-2), if the number of carbon atoms contained in the connecting group configured between the carbon atoms bonded by the polar group is too large, the flexibility of the end group represented by formula (3-2) is reduced, and it is sometimes difficult to evenly cover the entire surface of the protective layer. In the end group represented by formula (3-2), t is less than 5, so the alkylene chain of the main chain part of formula (3-2) will not be too long. Therefore, by the rigid alkylene chain length, the flexibility of the terminal part can be prevented from being reduced, and the interaction between the terminal hydroxyl group and the protective layer can be reduced.

[0225] Therefore, the lubricating layer containing the fluorine-containing ether compound whose linking group has a linear structure consisting of 1 to 5 atoms containing no oxygen atom forming an ether bond and containing no hydroxyl group-bonded carbon atoms has excellent adhesion to the protective layer, exhibits high corrosion resistance, and has a good adhesion suppression effect.

[0226] In the formula (3-2), t is preferably 1 or 2, and more preferably 1.

[0227] 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 2 or more and 3 or less. Therefore, s in formula (3-2) is preferably 0 or 1.

[0228] (R 3 (represented by a divalent connecting group)

[0229] In the fluorine-containing ether compound represented by formula (1), x R 3 It is a divalent linking group having 1 to 4 polar groups. 3 It is arranged between adjacent PFPE chains via methylene groups. 3 The fluorine-containing ether compound is brought into close contact with the protective layer. As a result, the lubricant containing the fluorine-containing ether compound of the present embodiment can form a thin lubricating layer with a sufficient coverage.

[0230] In formula (1), when x is 2, two R 3 They may be the same or different, but are preferably the same. 3 If the two R 3 The fluorine-containing ether compound can be easily and efficiently prepared.

[0231] In this specification, when x is 2, "2 R 3 The same refers to the two R 3 The atoms contained in R are located in the center of the molecular chain structure. 2Symmetrical configuration.

[0232] The x R in formula (1) 3 Each of the fluorinated ether compounds contains one or more polar groups. Therefore, when a lubricating layer is formed on a protective layer using a lubricant containing a fluorinated ether compound, a suitable interaction is generated between the lubricating layer and the protective layer. Therefore, the fluorinated ether compound represented by formula (1) has excellent adhesion to the protective layer, and a lubricating layer with good adhesion inhibition effect can be formed.

[0233] In addition, due to R 3 The number of polar groups contained is 4 or less, so in the lubricating layer containing the fluorine-containing ether compound, the polarity of the fluorine-containing ether compound can be suppressed from being too high, the fluorine-containing ether compound can be suppressed from agglomerating into a mass, and the lubricating layer can be suppressed from losing its smoothness. Therefore, the occurrence of adhesion caused by the collision between the lubricating layer and the magnetic head can be suppressed. In addition, if R 3 If the number of polar groups contained is 4 or less, the hydrophilicity of the fluorinated ether compound can be prevented from becoming too high, which would cause corrosive water to enter the magnetic recording medium. As a result, the fluorinated ether compound can form a lubricating layer with high corrosion resistance. 3 The number of polar groups contained is preferably 3 or less.

[0234] R 3 The polar groups contained are preferably selected from hydroxyl (-OH), carboxyl (-COOH), formyl (-(C=O)H), carbonyl (-(C=O)R 7 , R 7 is an organic group), a sulfone group (-SO3H), a cyano group (-CN), and a group having an amide bond (-NR 8 COR 9 or-CONR 10 R 11 , R 8 , R 9 , R 10 and R 11 are each independently a hydrogen atom or an organic group), an amino group (-NR 12 R 13 , R 12 and R 13 Each independently is a hydrogen atom or an organic group). As a group having an amide bond, as shown in the above formula, it includes both a group bonded to the carbon atom constituting the amide bond (for example, a formamide group (-C(=O)NH2)) and a group bonded to the nitrogen atom constituting the amide bond (for example, an acetamide group (-NHC(=O)CH3)). In the group having an amide bond, the above R 8 and R 9 can be bonded to each other to form a ring, the above R 10 and R 11The above R in the group having an amide bond may be bonded to each other to form a ring. 8 , R 9 , R 10 and R 11 Preferably, they are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group.

[0235] R 3 Preferably, each independently contains at least one polar group selected from a hydroxyl group, a cyano group, and a group having an amide bond. This is because the hydroxyl group, the cyano group, and the group having an amide bond are chemically stable, and the lubricating layer containing the fluorine-containing ether compound having these polar groups will not deteriorate for a long time. In addition, the acidity of the hydroxyl group, the cyano group, and the group having an amide bond is not too high, and it is not easy to corrode the substrate.

[0236] The x R in formula (1) 3 The 1 to 4 polar groups possessed by each may be partially or entirely the same or may be different from each other.

[0237] The x R in formula (1) 3 Preferably, each contains at least one hydroxyl group, more preferably x R 3 All polar groups are hydroxyl groups because the coating state of the protective layer by the fluorine-containing ether compound becomes more uniform.

[0238] The x R in formula (1) 3 Each of them is preferably a linking group having 1 to 50 carbon atoms, more preferably a linking group having 3 to 50 carbon atoms, further preferably a linking group having 3 to 20 carbon atoms, and most preferably a linking group having 4 to 15 carbon atoms. 3 If the number of carbon atoms of the linking group represented by is 1 or more, the hydrophobicity of the linking group can be ensured, thereby preventing water that causes corrosion from being attracted to the lubricating layer, and forming a lubricating layer with good corrosion resistance. 3 When the carbon number of the linking group represented by is 50 or less, the linking group has a flexible structure, and the adhesion between the lubricating layer containing the fluorinated ether compound and the protective layer becomes good. As a result, a lubricating layer capable of suppressing sticking can be obtained.

[0239] The x R in formula (1) 3 Preferably, the divalent linking group has oxygen atoms disposed at both ends. 3 The oxygen atoms at both ends of the divalent linking group represented by 3 The methylene groups (-CH2-) on both sides form ether bonds (-O-). These ether bonds impart moderate flexibility to the fluorine-containing ether compound represented by formula (1), making R 3 The polar group of the divalent linking group represented by has an increased affinity with the protective layer.

[0240] The x R in formula (1) 3 More preferably, each independently is a divalent linking group having 1 to 3 hydroxyl groups, oxygen atoms at both ends bonded to the adjacent methylene groups, and 3 to 50 carbon atoms.

[0241] More specifically, x R 3 Each independently is preferably any one selected from the group consisting of linking groups represented by the following formulae (4-1) to (4-6).

[0242]

[0243] In formula (4-1), u1 represents an integer of 0 to 6, and u2 represents an integer of 0 to 6, wherein at least one of u1 and u2 is 0, and the oxygen atom at the left terminal of formula (4-1) is in the same position as R in formula (1). 1 The methylene bond on the side, the oxygen atom on the right terminal and R 4 Side methylene bonding.

[0244] In formula (4-2), v represents an integer of 1 to 2, and the oxygen atom at the left terminal of formula (4-2) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R 4 Side methylene bonding.

[0245] In formula (4-3), w represents an integer of 0 to 6, and the oxygen atom at the left terminal of formula (4-3) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R 4 Side methylene bonding.

[0246] In formula (4-4), x1 represents an integer of 0 to 5, and x2 represents an integer of 0 to 5, wherein at least one of x1 and x2 is an integer of 1 to 5, and the oxygen atom at the left terminal of formula (4-4) is in the same position as R in formula (1). 1 The methylene bond on the side, the oxygen atom on the right terminal and R 4 Side methylene bonding.

[0247] In formula (4-5), y1 represents an integer of 1 to 5, y2 represents an integer of 1 to 5, and the oxygen atom at the left terminal of formula (4-5) is in the same position as R in formula (1). 1 The methylene bond on the side, the oxygen atom on the right terminal and R 4 Side methylene bonding.

[0248] In formula (4-6), z represents an integer of 1 to 6, and z R c and R dEach independently represents a hydrogen atom, a fluorine atom or a methyl group, and the oxygen atom at the left terminal of formula (4-6) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R 4 Side methylene bonding.

[0249] The linking group represented by formula (4-1) has a glycerol structure (-OCH2CH(OH)CH2O-) or a structure in which 1 to 6 methylene groups are added to the glycerol structure. Therefore, the linking group represented by formula (4-1) contains only one hydroxyl group, and the linking group maintains a low polarity. As a result, the water intrusion that causes corrosion of the magnetic recording medium can be effectively blocked, and a lubricating layer with a good corrosion inhibition effect on the magnetic recording medium can be formed.

[0250] In formula (4-1), since at least one of u1 and u2 is 0, the fluorinated ether compound represented by formula (1) has excellent flexibility, and the coating state of the protective layer with the fluorinated ether compound becomes more uniform. In the case where only one of u1 and u2 is 0, the value of the non-zero one of u1 and u2 is 1 to 6, preferably 1 to 4, and more preferably 1 to 3. This is because the linking group will not become too rigid, and a lubricating layer with better adhesion and excellent anti-sticking properties can be formed.

[0251] In formula (4-1), when only one of u1 and u2 is 0, there are u1 or u2 carbon atoms that are not bonded to either the polar group or the ether oxygen atom between the carbon atom bonded to the secondary hydroxyl group and the ether oxygen atom disposed at both ends to form an ether bond. Therefore, it becomes a fluorine-containing ether compound that can form a lubricating layer with excellent hydrophobicity and better corrosion resistance due to u1 or u2 methylene groups.

[0252] The linking group represented by formula (4-2) is a structure formed by connecting 2 to 3 glycerol structures (-OCH2CH(OH)CH2O-). The glycerol structure imparts flexibility to the linking group, so the linking group represented by formula (4-2) is extremely soft. As a result, the fluorinated ether compound represented by formula (1) has better adhesion and can form a lubricating layer with better anti-sticking properties.

[0253] In formula (4-2), v represents an integer of 1 to 2, and is preferably 1. When v is 2 or less, the fluorine-containing ether compound represented by formula (1) maintains low polarity, and a lubricating layer having further excellent corrosion resistance can be formed.

[0254] The connecting group represented by formula (4-3) has a structure in which the carbon atoms to which the hydroxyl groups are bonded are directly bonded to each other, or a structure in which the carbon atoms to which the hydroxyl groups are bonded are bonded via an alkylene group having 1 to 6 carbon atoms and not containing an ether bond. Therefore, the connecting group represented by formula (4-3) maintains a lower polarity than a connecting group having a structure in which the carbon atoms to which the hydroxyl groups are bonded are bonded via an oxygen atom and an alkylene group forming an ether bond. As a result, the water intrusion that causes the corrosion of the magnetic recording medium can be effectively blocked, and a lubricating layer with a good corrosion inhibition effect on the magnetic recording medium can be formed.

[0255] In formula (4-3), w represents an integer of 0 to 6, preferably 0 to 4. When w is 6 or less, the linking group represented by formula (4-3) does not become too rigid, and a fluorine-containing ether compound can form a lubricating layer having better adhesion and excellent anti-sticking properties.

[0256] In formula (4-3), when w is 1 or more, there are w carbon atoms that are not bonded to the polar group and the ether oxygen atom between the two carbon atoms bonded to the secondary hydroxyl group. Therefore, it becomes a fluorine-containing ether compound that has excellent hydrophobicity due to the w methylene groups and can form a lubricating layer with better corrosion resistance. When w is 1 or more, w is preferably 2 to 4.

[0257] The connecting group represented by formula (4-4) has a structure in which the carbon atoms bonded to the hydroxyl groups are bonded to each other via a linear connecting chain of 4 or more atoms containing oxygen atoms forming an ether bond. The fluorinated ether compound having the connecting group represented by formula (4-4) fully maintains the distance between the two hydroxyl groups in formula (4-4), so the intramolecular interaction of the hydroxyl groups is suppressed, and a lubricating layer having good adsorption capacity for the protective layer can be formed. Therefore, the lubricating layer containing the fluorinated ether compound represented by formula (1) has better adhesion and better adhesion resistance.

[0258] In formula (4-4), x1 and x2 each independently represent an integer of 0 to 5, and at least one of x1 and x2 is an integer of 1 to 5. Since the total value of x1 and x2 of the linking group represented by formula (4-4) is 1 or more, the hydrophobicity of the fluorinated ether compound becomes good, and the lubricating layer containing it is not easy to introduce water that causes corrosion, and has good corrosion resistance. x1 and x2 are preferably each independently an integer of 3 or less. This is because the linking group will not become too rigid, and a lubricating layer with better adhesion and excellent adhesion resistance can be formed. In addition, the total value of x1 and x2 is preferably 4 or less. In order to impart moderate flexibility to the linking group represented by formula (4-4), it is preferred that one of x1 and x2 is 0.

[0259] The linking group represented by formula (4-5) has a structure having three hydroxyl groups, and carbon atoms to which adjacent hydroxyl groups are bonded are bonded to each other via a linear linking chain of 4 or more atoms including an oxygen atom forming an ether bond.

[0260] The fluorinated ether compound having a connecting group represented by formula (4-5) has three hydroxyl groups, so it is easy to form an interaction between the hydroxyl group and the protective layer, and a lubricating layer with good adhesion to the protective layer can be formed. In addition, the fluorinated ether compound having a connecting group represented by formula (4-5) fully maintains the distance between adjacent hydroxyl groups among the three hydroxyl groups in formula (4-5), so the intramolecular interaction of the hydroxyl group is suppressed, and a lubricating layer with good adsorption capacity to the protective layer can be formed. Therefore, the lubricating layer containing the fluorinated ether compound represented by formula (1) has better adhesion and better adhesion resistance.

[0261] In formula (4-5), y1 and y2 each independently represent an integer of 1 to 5. In the linking group represented by formula (4-5), since y1 and y2 are both 1 or more, the hydrophobicity of the fluorinated ether compound becomes good, and the lubricating layer containing it is not easy to introduce water that causes corrosion, and has good corrosion resistance. In order to give appropriate flexibility to the linking group represented by formula (4-5), y1 and y2 are preferably each independently 1 to 3, and most preferably both are 1. In addition, in order to make the coating state of the fluorinated ether compound on the protective layer more uniform, it is preferred that y1 and y2 are the same.

[0262] The connecting group represented by formula (4-6) is a structure in which the carbon atoms bonded to the hydroxyl groups are bonded to each other by means of a straight-chain connecting chain of more than 7 atoms containing two ether bonds. Since a sufficient distance is maintained between the two hydroxyl groups in the connecting group represented by formula (4-6), intramolecular interactions are suppressed. Therefore, the connecting group represented by formula (4-6) has good adsorption capacity for the protective layer. As a result, the fluorine-containing ether compound having the connecting group represented by formula (4-6) has better adhesion and can form a lubricating layer with excellent adhesion resistance.

[0263] In formula (4-6), z represents an integer of 1 to 6. In order to impart appropriate flexibility to the linking group represented by formula (4-6), z is preferably 4 or less. In order to impart sufficient hydrophobicity to the linking group represented by formula (4-6), z is preferably 2 or more.

[0264] The z R in formula (4-6) c and R d Each independently represents a hydrogen atom, a fluorine atom or a methyl group. For ease of preparation, preferably z (-CR c R d-) are each any one of -CH2-, -CH(CH3)-, -C(CH3)2-, and -CF2-.

[0265] In z (-CR c R d When -) is only one or more -CH2-, the linking group represented by formula (4-6) becomes flexible compared with the case where it contains -CH(CH3)- and / or -C(CH3)2-, which is preferred.

[0266] In addition, in z (-CR c R d -) contains -CH(CH3)- and / or -C(CH3)2-, and z (-CR c R d Compared with the case where all -) are -CH2-, the volume is moderately large, and the intramolecular interaction between the hydroxyl groups possessed by the linking group represented by formula (4-6) can be effectively suppressed, which is preferred.

[0267] In addition, in z (-CR c R d When -) contains one or more -CF2-, the affinity of the linking group represented by formula (4-6) for water is reduced, and it is less likely to introduce water that causes corrosion, which is preferred.

[0268] (R 2 PFPE chain represented by

[0269] In the fluorine-containing ether compound represented by formula (1), (x+1) R 2 Each is independently a perfluoropolyether chain (hereinafter, sometimes referred to as a "PFPE chain"). 2 When a lubricant containing the fluorinated ether compound of this embodiment is applied onto the protective layer to form a lubricating layer, the PFPE chain represented by R covers the surface of the protective layer and imparts lubricity to the lubricating layer, thereby reducing the friction between the magnetic head and the protective layer. 2 The PFPE chain represented by can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound.

[0270] In the fluorine-containing ether compound represented by formula (1), (x+1) R 2 They may be partially or completely the same, or they may be different. Preferably, (x+1) R 2 This is because the coating state of the protective layer with the fluorine-containing ether compound becomes uniform, forming a lubricating layer with better adhesion. (x+1) R 2 Two or more R 2 The same means that (x+1) R 2In the case of repeating units containing two or more PFPE chains, the same structure of R 2 The same R 2 It also includes R 2 .

[0271] As R 2 The PFPE chain represented by may be a PFPE chain composed 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.

[0272] Preferably, (x+1) R in formula (1) 2 Each independently is a PFPE chain represented by the following formula (5) derived from, for example, a polymer or copolymer of a perfluoroalkylene oxide.

[0273] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(5)

[0274] In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20. However, w2, w3, w4, and w5 are not all 0 at the same time. w1 and w6 represent average values ​​of the number of CF2, and each independently represents 1 to 3. The arrangement order of the repeating units (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) in formula (5) is not particularly limited.

[0275] In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and are each independently 0 to 20, preferably 0 to 15, and more preferably 0 to 10.

[0276] In formula (5), w1 and w6 are average values ​​representing the number of CF2, and each independently represents 1 to 3. w1 and w6 are determined based on the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (5).

[0277] In formula (5), (CF2O), (CF2CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) are repeating units. The arrangement order of the repeating units in formula (5) is not particularly limited. In addition, the number of types of repeating units in formula (5) is not particularly limited.

[0278] Preferably, (x+1) R in formula (1) 2 Each independently represents any one selected from the PFPE chains represented by the following formulae (5-1) to (5-4).

[0279] If (x+1) R 2 Each independently is any one of the PFPE chains represented by formulas (5-1) to (5-4), and a lubricating layer having good lubricity can be obtained. 2 When each is independently selected from any one of the PFPE chains represented by formulas (5-1) to (5-4), 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, it becomes a fluorine-containing ether compound with appropriate hardness. Therefore, the fluorine-containing ether compound coated on the protective layer is not easy to accumulate on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage. In addition, the (x+1) R 2 A lubricating layer containing a fluorinated ether compound each independently selected from the PFPE chains represented by formulae (5-1) to (5-4) is more dense and can further suppress sticking, and is therefore preferred.

[0280] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(5-1)

[0281] In the formula (5-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20.

[0282] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(5-2)

[0283] In the formula (5-2), j represents an average degree of polymerization and is 1 to 15.

[0284] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(5-3)

[0285] In the formula (5-3), k represents an average degree of polymerization and is 1 to 10.

[0286] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(5-4)

[0287] In the formula (5-4), w8 and w9 represent average polymerization degrees, and each independently represents 1 to 20, and w7 and w10 represent average values ​​of the number of CF2 groups, and each independently represents 1 to 2.

[0288] In formula (5-1), the arrangement order of (OCF2CF2) and (OCF2) as repeating units is not particularly limited. In formula (5-1), the number h of (OCF2CF2) and the number i of (OCF2) may be the same or different. The PFPE chain represented by formula (5-1) may be a polymer of (OCF2CF2). In addition, the PFPE chain represented by formula (5-1) may be any one of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF2CF2) and (OCF2).

[0289] In formulas (5-1) to (5-3), 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, it is a fluorine-containing ether compound that can obtain a lubricating layer with good lubricity. In addition, in formulas (5-1) to (5-3), 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 the lubricant containing it 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.

[0290] In formula (5-4), the arrangement order of (CF2CF2CF2O) and (CF2CF2O) as repeating units is not particularly limited. In formula (5-4), the number w8 of (CF2CF2CF2O) representing the average degree of polymerization and the number w9 of (CF2CF2O) may be the same or different. Formula (5-4) may include any one of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF2CF2CF2O) and (CF2CF2O).

[0291] In formula (5-4), w8 and w9, which represent the average degree of polymerization, are each independently 1 to 20, preferably 1 to 15, and more preferably 1 to 10.

[0292] w7 and w10 in formula (5-4) are average values ​​of the number of CF2, and each independently represents 1 to 2. w7 and w10 are determined based on the structure of the repeating unit disposed at the end of the chain structure in the PFPE chain represented by formula (5-4).

[0293] 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 (AT), (BA) to (BL), (CA) to (CF), and (DA) to (DH).

[0294] When the fluorinated ether compound represented by formula (1) is any one of the compounds represented by the following formulas (AA) to (AT), (BA) to (BL), (CA) to (CF), and (DA) to (DH), the raw materials are easy to obtain and a lubricating layer can be formed that has better corrosion resistance and a good adhesion inhibition effect even if the thickness is thin.

[0295] In the compounds represented by the following formulas (AA) to (AT), (BA) to (BL), (CA) to (CF), (DA) to (DH), Rf1, Rf2, and Rf3 representing the PFPE chain are the following structures. That is, in the compounds represented by the following formulas (AA) to (AT), (BA) to (BJ), (CA) to (CF), (DA), and (DB), Rf1 is the PFPE chain represented by the above formula (5-1). In the compounds represented by the following formulas (BK), (DC) to (DH), Rf2 is the PFPE chain represented by the above formula (5-2). In the compound represented by the following formula (BL), Rf3 is the PFPE chain represented by the above formula (5-3). In the formulae (AA) to (AT), (BA) to (BL), (CA) to (CF), and (DA) to (DH), h and i in Rf1, j in Rf2, and k in Rf3 representing PFPE chains are values ​​indicating average polymerization degrees and are not necessarily integers.

[0296]

[0297] The compounds represented by the following formulae (AA) to (AN), wherein x in formula (1) is 1. 1 and R 4 are the same and are terminal groups represented by any one of the above formulae (2-1) to (2-6). 2 The same is the PFPE chain represented by the above formula (5-1). 3 It is a connecting group represented by the above formula (4-1).

[0298] The compounds represented by the following formulae (AO) to (AT), wherein x in the formula (1) is 1. 1 is the terminal group represented by the above formula (2-1), R 4 It is an end group represented by any one of the above formulas (3-1), (3-2), (3-1) and (3-2). 2 The same is the PFPE chain represented by the above formula (5-1). 3It is a connecting group represented by the above formula (4-1).

[0299] The compounds represented by the following formulae (BA) to (BJ), wherein x in the formula (1) is 1. 1 and R 4 The same as the terminal group represented by the above formula (2-1). 2 The same is the PFPE chain represented by the above formula (5-1). 3 It is a linking group represented by any one of the above formulae (4-1) to (4-6).

[0300] The compounds represented by the following formulas (BK) and (BL), wherein x in the formula (1) is 1. 1 and R 4 The same as the terminal group represented by the above formula (2-1). 2 The same is the PFPE chain represented by the above formula (5-2) or (5-3). 3 It is a connecting group represented by the above formula (4-1).

[0301] The compounds represented by the following formulae (CA) to (CD), wherein x in formula (1) is 2. 1 and R 4 are the same and are terminal groups represented by any one of the above formulae (2-1) to (2-4). 2 The same is the PFPE chain represented by the above formula (5-1). 3 The same is the linking group represented by the above formula (4-1).

[0302] The compounds represented by the following formulae (CE) to (CF), wherein x in formula (1) is 2. 1 and R 4 The same as the terminal group represented by the above formula (2-1). 2 The same is the PFPE chain represented by the above formula (5-1). 3 The same is the linking group represented by the above formula (4-2) or (4-3).

[0303]

[0304] In the two Rf1 in the formula (AA), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0305] In the two Rf1 in the formula (AB), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0306] In the two Rf1 in the formula (AC), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0307] In the two Rf1 in the formula (AD), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0308] In the two Rf1 in the formula (AE), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0309]

[0310] In the two Rf1 in the formula (AF), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0311] In the two Rf1 in the formula (AG), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0312] In the two Rf1 in the formula (AH), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0313] In the two Rf1 in the formula (AI), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0314] In the two Rf1 in the formula (AJ), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0315]

[0316] In the two Rf1 in the formula (AK), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0317] In the two Rf1 in the formula (AL), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0318] In the two Rf1 in the formula (AM), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0319] In the two Rf1 in the formula (AN), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0320] In the two Rf1 in the formula (AO), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0321]

[0322] In the two Rf1 in the formula (AP), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0323] In the two Rf1 in the formula (AQ), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0324] In the two Rf1 in the formula (AR), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0325] In the two Rf1 in the formula (AS), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0326] In the two Rf1 in the formula (AT), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0327]

[0328] In the two Rf1 in the formula (BA), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0329] In the two Rf1 in the formula (BB), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0330] In the two Rf1 in the formula (BC), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0331] In the two Rf1 in the formula (BD), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0332] In the two Rf1 in the formula (BE), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0333]

[0334] In the two Rf1 in the formula (BF), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0335] In the two Rf1 in the formula (BG), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0336] In the two Rf1 in the formula (BH), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0337] In the two Rf1 in the formula (BI), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0338] In the two Rf1 in the formula (BJ), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the two Rf1 may be the same or different.

[0339]

[0340] In the two Rf2 in the formula (BK), j represents the average degree of polymerization and is 1 to 15. The j in the two Rf2 may be the same or different.

[0341] In the two Rf3 in the formula (BL), k represents the average degree of polymerization and is 1 to 10. The k in the two Rf3 may be the same or different.

[0342] In the three Rf1 in the formula (CA), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.

[0343] In the three Rf1 in the formula (CB), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.

[0344] In the three Rf1 in the formula (CC), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.

[0345]

[0346] In the three Rf1 in the formula (CD), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.

[0347] In the three Rf1 in the formula (CE), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.

[0348] In the three Rf1 in the formula (CF), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20. The h and i in the three Rf1 may be different from each other, or may be partially or entirely the same.

[0349] In the compounds represented by the following formulae (DA) to (DG), x in formula (1) is 1. 1 and R 4 The same is the terminal group represented by any one of the above formulae (2-1), (2-2), (2-6) and (2-7). 2 The same is the PFPE chain represented by the above formula (5-1) or (5-2). 3 It is a linking group represented by the above formula (4-1) or (4-4).

[0350] A compound represented by the following formula (DH), wherein x in the formula (1) is 2. 1 and R 4 The same as the terminal group represented by the above formula (2-2). 2 The same is the PFPE chain represented by the above formula (5-2). 3 The same is the linking group represented by the above formula (4-1).

[0351]

[0352] In the two Rf1 in the formula (DA), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0. The h in the two Rf1 may be the same or different.

[0353] In the two Rf1 in the formula (DB), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0. The h in the two Rf1 may be the same or different.

[0354] In the two Rf2 in the formula (DC), j represents the average degree of polymerization and is 1 to 15. The j in the two Rf2 may be the same or different.

[0355] In the two Rf2 in the formula (DD), j represents the average degree of polymerization and is 1 to 15. The j in the two Rf2 may be the same or different.

[0356] In the two Rf2 in the formula (DE), j represents the average degree of polymerization and is 1 to 15. The j in the two Rf2 may be the same or different.

[0357] In the two Rf2 in the formula (DF), j represents the average degree of polymerization and is 1 to 15. The j in the two Rf2 may be the same or different.

[0358] In the two Rf2 in the formula (DG), j represents the average degree of polymerization and is 1 to 15. The j in the two Rf2 may be the same or different.

[0359] In the three Rf2 in the formula (DH), j represents the average degree of polymerization and is 1 to 15. The j in the three Rf2 may be different from each other or may be partially or entirely the same.

[0360] 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, more preferably in the range of 500 to 5,000, and particularly preferably in the range of 1,000 to 3,000. If the number average molecular weight is 500 or more, the lubricating layer formed by the lubricant containing the fluorinated ether compound of the present embodiment has excellent heat resistance. The number average molecular weight of the fluorinated ether compound is more preferably 1,000 or more. In addition, if the number average molecular weight is 10,000 or less, the viscosity of the fluorinated ether compound becomes appropriate, and a thin lubricating layer can be easily formed by applying a lubricant containing it. The number average molecular weight of the fluorinated ether compound is preferably 5,000 or less in order to form a viscosity that is easy to handle when used as a lubricant.

[0361] The number average molecular weight (Mn) of the fluorinated ether compound was determined by using AVANCE III 400 prepared by Bruker BioSpin.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 of the F-NMR measurement to determine the number average molecular weight. In the NMR (nuclear magnetic resonance) measurement, the sample was diluted in a hexafluorobenzene / d-acetone (4 / 1 v / v) solvent for measurement. 19 The standard of F-NMR chemical shift was assigned to the peak of hexafluorobenzene at -164.7 ppm. 1 The standard for H-NMR chemical shifts was the peak of acetone assigned to 2.2 ppm.

[0362] 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.

[0363] In the present embodiment, the method of molecular weight fractionation is not particularly limited, and for example, molecular weight fractionation by silica gel column chromatography, gel permeation chromatography (GPC), or the like, molecular weight fractionation by supercritical extraction, or the like can be used.

[0364] "Method of preparation"

[0365] The method for preparing 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 prepared by a conventionally known method. The fluorine-containing ether compound of the present embodiment can be prepared by, for example, the following method.

[0366] [First preparation method (when x is 1)]

[0367] (R 1 and R 4 Same, two R 2 Same as

[0368] Prepare R in formula (1) 2 The corresponding perfluoropolyether chains have fluoro compounds with hydroxymethyl groups (-CH2OH) at both ends.

[0369] 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 The epoxy compound (first raw material compound) of the corresponding group) is reacted (first reaction). Thus, 2 One end of the corresponding perfluoropolyether chain has 1 The corresponding group (= with R 4 The intermediate compound 1 of the corresponding group).

[0370] When the fluorine-based compound is reacted with the first raw material compound, the hydroxyl group of the first raw material compound may be protected with an appropriate protecting group and then reacted with the fluorine-based compound.

[0371] As a first raw material compound having two protected hydroxyl groups in a 1,2-diol structure, having the same structure as R in formula (1), 1 The corresponding group (= with R 4 The epoxy compound having a corresponding group) may be, for example, the compounds represented by the following formulae (6-1) to (6-16).

[0372] As the first raw material compound, the epoxy compound may be replaced by a compound having the same R as in formula (1): 1 The corresponding group (= with R 4 As the compound having a leaving group, compounds represented by the following formulas (6-24) and (6-25) can be used. In formulas (6-24) and (6-25), Ts represents a tosyl group. In formula (6-25), MOM represents a methoxymethyl group.

[0373]

[0374] The epoxy compound represented by the formula (6-1) as an example of the first raw material compound can be prepared, for example, by the method represented by the following formula (7-1). That is, it can be prepared by the following method: 1 (=R 4 ) and a portion of X in formula (2) (X') and a portion of the 1,2-diol structure (-X'-CH(OH)-CH2OH) bonded thereto, and a halogen compound having a portion corresponding to a portion of X in formula (2) and an epoxy group, that is, an epibromohydrin represented by formula (8-1) are reacted. As represented by formula (7-1), as the alcohol compound, an alcohol compound in which two hydroxyl groups of the 1,2-diol structure are appropriately protected can be used.

[0375]

[0376] In addition, an epoxy compound represented by formula (6-5) as another example of the first raw material compound can be prepared, for example, by the method represented by the following formula (7-2). That is, 3-butene-1-ol, an alcohol compound having a part corresponding to a part of X in formula (2) and a vinyl group, and a group having a vinyl group corresponding to R 1 (=R 4) is reacted with a halogen compound (in this embodiment, a halogen compound obtained by brominating the hydroxyl group of sorbital) of a part (X') of X in formula (2) of the present invention and a 1,2-diol structure (-X'-CH(OH)-CH2OH) bonded thereto. Then, meta-chloroperbenzoic acid (mCPBA) is allowed to act on the obtained compound for oxidation to produce. As shown in formula (7-2), as the halogen compound, a halogen compound in which the two hydroxyl groups of the 1,2-diol structure are appropriately protected can be used.

[0377]

[0378] In addition, an epoxy compound represented by formula (6-10) as another example of the first raw material compound can be prepared, for example, by the method represented by the following formula (7-3). That is, a diol compound having a portion corresponding to a portion of X in formula (2) and a diol compound having a portion corresponding to R 1 (=R 4 ) is reacted with a halogen compound (in this embodiment, a halogen compound obtained by brominating the hydroxyl group of sorbital) that is a part (X′) of X in formula (2) and a part of the 1,2-diol structure (-X′-CH(OH)-CH2OH) bonded thereto. Then, the obtained alcohol compound is reacted with a halogen compound having a part corresponding to a part of X in formula (2) and an epoxy group, i.e., epibromohydrin represented by formula (8-1). As shown in formula (7-3), as a halogen compound, a halogen compound in which the two hydroxyl groups of the 1,2-diol structure are appropriately protected can be used, similarly to the halogen compound used in the method shown in formula (7-2).

[0379]

[0380] As the first raw material compound, 1 The corresponding group (= with R 4 The epoxy compound (or the compound having a leaving group) having a corresponding group may be purchased from a commercial product and used.

[0381] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1 generated in the first reaction is reacted with R in the formula (1). 3 A compound having an epoxy group at one end of the corresponding part and a halogen bonded to the other end, or R in formula (1) 3 The corresponding part is reacted with a compound having epoxy groups at both ends (second raw material compound) (second reaction).

[0382] As the second raw material compound, R in the formula (1) 3A compound having an epoxy group at one end of the corresponding part and a halogen bonded to the other end, or R in formula (1) 3 As the compound having epoxy groups at both ends of the corresponding part, for example, compounds represented by the following formulae (8-1) to (8-12) can be used. THP in the following formula (8-7) represents a tetrahydropyranyl group.

[0383]

[0384] The second raw material compound can be prepared, for example, by the following method. That is, it can be prepared by the following method: 3 The diol corresponding to a part of the linking group represented by is reacted with 2 times the molar amount of epibromohydrin.

[0385] For example, when preparing a compound represented by formula (8-8) as an example of the second raw material compound, it can be prepared by reacting 1,4-butanediol with a 2-fold molar amount of epibromohydrin represented by formula (8-1) as shown in the following formula (9-1).

[0386]

[0387] The second raw material compound can be prepared by the method shown below. 3 The halogen compound corresponding to the epoxy group of the connecting group and having R 3 The alcohol of the alkenyl group corresponding to a part of the connecting group represented by is subjected to addition reaction. At this time, the alcohol having an alkenyl group is reacted with the halogen compound in an amount of 2 times the molar amount of the halogen compound. Then, the method of oxidizing the obtained compound by allowing meta-chloroperbenzoic acid (mCPBA) to act can be used to prepare it. Before allowing meta-chloroperbenzoic acid (mCPBA) to act on the compound obtained by the addition reaction to oxidize it, the hydroxyl group generated by the addition reaction can be protected by a known method.

[0388] For example, as shown in the following formula (9-2), a compound represented by formula (8-7) as another example of the second raw material compound can be prepared by the following method: after the epibromohydrin represented by formula (8-1) is subjected to an addition reaction with a 2-fold molar amount of 3-butene-1-ol, the hydroxyl group generated by the addition reaction is protected with dihydropyran (DHP), and then oxidized by the action of m-chloroperbenzoic acid (mCPBA). THP in the following formula (9-2) represents tetrahydropyranyl.

[0389]

[0390] When the compound obtained after the second reaction has a hydroxyl group protected by a protecting group, a deprotection reaction is carried out by a known method. By carrying out the above steps, a compound in which x is 1 and R 1 With R 4 Same, 2 R 2 The same fluorinated ether compounds.

[0391] [Second preparation method (when x is 1)]

[0392] (R 1 and R 4 Different and / or two R 2 Not at the same time)

[0393] First, make the 1 Side R 2 The corresponding perfluoropolyether chain has a hydroxyl group at one end of the fluorine compound with a hydroxymethyl group at both ends, and a hydroxyl group having R 1 The epoxy compound of the corresponding group (or the compound having a leaving group) is reacted to obtain the intermediate compound 1a (first reaction).

[0394] As with R 1 As the epoxy compound of the corresponding group (or the compound having a leaving group), for example, any one compound selected from the above-mentioned first raw material compound can be used.

[0395] Next, make the 4 Side R 2 The corresponding perfluoropolyether chain has a hydroxyl group at one end of the fluorine compound with a hydroxymethyl group at both ends, and a hydroxyl group having R 4 The corresponding group is reacted with an epoxy compound (or a compound having a leaving group) to obtain an intermediate compound 1b (second reaction).

[0396] In the second preparation method, R 1 With R 4 Same (ie, R 1 and R 4 When the fluorine-containing ether compound is a terminal group having the same terminal group as R 4 The epoxy compound (or the compound having a leaving group) corresponding to the group is used with the epoxy compound having R 1 The epoxy compounds (or compounds having a leaving group) of the corresponding groups are the same compounds.

[0397] In the second preparation method, R 1 With R 4 Different, R 1 and R 4When the terminal groups are all fluorinated ether compounds represented by formula (2), as the compound having R 4 The epoxy compound (or compound having a leaving group) having a corresponding group can be, for example, any one compound selected from the first raw material compound and having a group corresponding to R 1 The epoxy compounds (or compounds having a leaving group) of the corresponding groups are different compounds.

[0398] In addition, in the second preparation method, R 1 With R 4 Different, R 1 is the terminal group represented by formula (2), R 4 is a terminal group (R) not belonging to formula (2) 1 and R 4 When only one of the fluorinated ether compounds is a terminal group represented by formula (2), as a fluorinated ether compound having R 4 The corresponding group of epoxy compounds, using the intermediate compound 1b obtained after the reaction with R 4 The corresponding part does not belong to the epoxy compound (third raw material compound) of the formula (2).

[0399] As the third raw material compound, for example, epoxy compounds represented by the following formulae (6-17) to (6-23) can be used. In the formulae (6-17), (6-18), (6-21) to (6-23), THP represents a tetrahydropyranyl group.

[0400]

[0401] Next, the intermediate compound 1a obtained in the first reaction is reacted with any compound selected from the second raw material compound. 1 Side R 2 One end of the corresponding perfluoropolyether chain has 1 The corresponding group, the other end has 3 The corresponding epoxy intermediate compound 2a (third reaction).

[0402] It should be noted that in the third reaction, a compound which is the same as R in formula (1) may be used instead of the second raw material compound. 3 The corresponding compound has an epoxy group at one end and an alkenyl group bonded to the other end, and the double bond of the generated compound is oxidized to prepare an intermediate compound 2a having an epoxy group.

[0403] Next, the intermediate compound 1b obtained in the second reaction is reacted with the intermediate compound 2a obtained in the third reaction (fourth reaction).

[0404] When the compound obtained after the fourth reaction has a hydroxyl group protected by a protecting group, a deprotection reaction is carried out by a known method. By carrying out the above steps, a compound in which x is 1 and R 1 With R 4 Different and / or 2 R 2 Different fluorinated ether compounds.

[0405] [Third preparation method (when x is 2)]

[0406] (R 1 With R 4 Same, 2 R 3 Same, R 1 Side R 2 With R 4 Side R 2 Same as

[0407] First, the same operation as in the first preparation method is performed to obtain 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 (first reaction) of the corresponding group.

[0408] Next, prepare the R 2 The corresponding perfluoropolyether chain is provided with a fluoro compound having a hydroxymethyl group (-CH2OH) at both ends. Next, the hydroxyl groups of the hydroxymethyl groups provided at both ends of the fluoro compound are reacted with any one of the second raw material compounds. Thus, a fluoro compound having a hydroxymethyl group at the center of the molecule is obtained. 2 The corresponding perfluoropolyether chain has two ends with R 3 The corresponding epoxy intermediate compound 3a (second reaction).

[0409] It should be noted that in the second reaction, a compound which is the same as R in formula (1) may be used instead of the second raw material compound. 3 The corresponding part has an epoxy group at one end and an alkenyl group bonded to the other end, and the double bond of the generated compound is oxidized to prepare an intermediate compound 3a having epoxy groups at both ends.

[0410] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1 obtained in the first reaction is reacted with the epoxy groups disposed at both ends of the intermediate compound 3a (third reaction).

[0411] When the compound obtained after the third reaction has a hydroxyl group protected by a protecting group, a deprotection reaction is carried out by a known method. By carrying out the above steps, a compound in which x is 2 and R 1 With R 4 Same, 2 R 3 Same, R 1 Side R 2 With R 4 Side R 2 The same fluorinated ether compounds.

[0412] [The fourth preparation method (when x is 2)]

[0413] (R 1 Side R 3 With R 4 Side R 3 Same, R 1 With R 4 Different and / or R 1 Side R 2 With R 4 Side R 2 Not at the same time)

[0414] In the first reaction of the third production method, intermediate compound 1a and intermediate compound 1b in the second production method are obtained instead of intermediate compound 1. Then, the same operation as the second reaction of the third production method is performed to obtain intermediate compound 3a. Then, intermediate compound 1a and intermediate compound 1b are reacted with epoxy groups disposed at both ends of intermediate compound 3a in sequence.

[0415] When the compound obtained after the above steps has a hydroxyl group protected by a protecting group, a deprotection reaction is carried out by a known method. 1 Side R 3 With R 4 Side R 3 Same, R 1 With R 4 Different and / or R 1 Side R 2 With R 4 Side R 2 Different fluorinated ether compounds.

[0416] [Fifth Preparation Method (when x is 2)]

[0417] [R 1 Side R 3 With R 4 Side R 3 Different, R 1 With R4 Same, R 1 Side R 2 With R 4 Side R 2 Same as]

[0418] In the second reaction of the third preparation method, R 2 The corresponding perfluoropolyether chain is provided with a fluoro compound having a hydroxymethyl group (-CH2OH) at both ends and a fluoro compound selected from the second raw material compound having the same R 1 Side R 3 Then, the obtained compound is reacted with a compound selected from the above second raw material compound having a 4 Side R 3 Any one of the corresponding compounds is reacted to obtain the intermediate compound 3b.

[0419] Then, the third reaction was carried out in the same manner as in the third production method except that the intermediate compound 3b was used instead of the intermediate compound 3a.

[0420] When the compound obtained after the third reaction has a hydroxyl group protected by a protecting group, a deprotection reaction is carried out by a known method. By carrying out the above steps, a compound in which x is 2 and R 1 Side R 3 With R 4 Side R 3 Different, R 1 With R 4 Same, R 1 Side R 2 With R 4 Side R 2 The same fluorinated ether compounds.

[0421] In formula (1), x is 2 and R 2 The corresponding perfluoropolyether chain and R 1 Side R 2 and / or R 4 Side R 2 The same fluorine-containing ether compound and the different fluorine-containing ether compound can be prepared by appropriately selecting the fluorine-containing ether compound having an R 2 The corresponding perfluoropolyether chain is prepared by the type of fluorine compound.

[0422] Therefore, the fluorinated ether compound having R at the center of the molecule used in the third to fifth production methods for producing the fluorinated ether compound wherein x in the formula (1) is 2 2The corresponding perfluoropolyether chain of the fluorine compound can be combined with other R 2 The fluorine compounds of the corresponding perfluoropolyether chains may be the same or different.

[0423] In addition, the method for producing the fluorine-containing ether compound of the present embodiment is not limited to the first to fifth production methods described above, and for example, the following method may be used.

[0424] Prepare R in formula (1) 2 The corresponding perfluoropolyether chain (when x is 2, 1 Side R 2 and / or R 4 Side R 2 The corresponding perfluoropolyether chain) has fluoro compounds with hydroxymethyl (-CH2OH) at both ends.

[0425] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the fluorine-based compound is reacted with a halogen compound having a vinyl group at the terminal, thereby obtaining an intermediate compound 1c having a vinyl group at one end of a chain structure including a perfluoropolyether chain.

[0426] Then, the intermediate compound 1c is used instead of the intermediate compound 1, intermediate compound 1a, or intermediate compound 1b in the first to fifth production methods to carry out the final reaction of the first to fifth production methods. Thus, a compound having a vinyl group at one or both ends of a chain structure including a perfluoropolyether chain is obtained.

[0427] Next, the vinyl groups at one or both ends of the obtained compound are oxidized to obtain a compound having an epoxy group at one or both ends of a chain structure including a perfluoropolyether chain. Then, the epoxy group disposed at one or both ends of the obtained compound is subjected to a ring-opening reaction to convert the epoxy group into 1,2-diol.

[0428] By carrying out the above steps, the fluorine-containing ether compound represented by the formula (1) can also be produced.

[0429] [Lubricant for magnetic recording media]

[0430] The lubricant for magnetic recording media according to the present embodiment contains the fluorine-containing ether compound represented by the above formula (1).

[0431] The lubricant of the present embodiment may be mixed with a known material used as a lubricant material as needed within a range not impairing the properties of the fluorine-containing ether compound represented by the above formula (1).

[0432] Specific examples of known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco), etc. The number average molecular weight of the known material mixed with the lubricant of the present embodiment is preferably 1,000 to 10,000.

[0433] 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 70% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more.

[0434] 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 corrosion resistance and a high adhesion suppressing effect.

[0435] [Magnetic recording media]

[0436] The magnetic recording medium of the present embodiment includes at least a magnetic layer, a protective layer, and a lubricating layer provided in this order on a substrate.

[0437] 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.

[0438] Figure 1 It is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0439] 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 .

[0440] "Substrate"

[0441] 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.

[0442] In addition, as the substrate 11, a non-magnetic substrate made of non-metallic materials such as glass, ceramics, silicon, silicon carbide, carbon, and resin can be used, and a non-magnetic substrate in which a film of NiP or NiP alloy is formed on a base made of these non-metallic materials can also be used.

[0443] "Attachment Layer"

[0444] The adhesive layer 12 prevents corrosion of the substrate 11 when the substrate 11 and the soft magnetic layer 13 provided on the adhesive layer 12 are arranged in contact with each other.

[0445] 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.

[0446] "Soft magnetic layer"

[0447] The soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer composed of a Ru film, and a second soft magnetic film are sequentially laminated. That is, the soft magnetic layer 13 preferably has a structure in which the soft magnetic films above and below the intermediate layer are antiferromagnetically coupled (AFC) by sandwiching an intermediate layer composed of a Ru film between two soft magnetic films.

[0448] Examples of the material of the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy.

[0449] In the CoFe alloy used in the first soft magnetic film and the second soft magnetic film, it is preferred to add any one of Zr, Ta, and Nb. This can promote the amorphization of the first soft magnetic film and the second soft magnetic film. As a result, the orientation of the first base layer (seed layer) can be improved, and the floating amount of the magnetic head can be reduced.

[0450] The soft magnetic layer 13 can be formed by, for example, sputtering.

[0451] "First Base Layer"

[0452] The first base layer 14 is a layer that controls the orientation and crystal size of the second base layer 15 and the magnetic layer 16 provided thereon.

[0453] 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.

[0454] The first base layer 14 can be formed by, for example, sputtering.

[0455] "Second base layer"

[0456] The second underlayer 15 is a layer that controls and improves the orientation of the magnetic layer 16. The second underlayer 15 is preferably a layer composed of Ru or a Ru alloy.

[0457] The second base layer 15 may be composed of a single layer or a plurality of layers. When the second base layer 15 is composed of a plurality of layers, all the layers may be composed of the same material, or at least one layer may be composed of a different material.

[0458] The second base layer 15 can be formed by, for example, sputtering.

[0459] "Magnetic layer"

[0460] The magnetic layer 16 is composed of a magnetic film whose easy magnetization axis is oriented in a vertical or horizontal direction relative to the substrate surface. The magnetic layer 16 is a layer containing Co and Pt. In order to improve the SNR characteristics, the magnetic layer 16 may also be a layer containing oxide, Cr, B, Cu, Ta, Zr, etc.

[0461] 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 .

[0462] The magnetic layer 16 may be composed of a single layer or a plurality of magnetic layers including materials having different compositions.

[0463] For example, in the case where the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer stacked in sequence from the bottom, the first magnetic layer is preferably a granular structure composed of a material containing Co, Cr, Pt, and further containing an oxide. As the oxide contained in the first magnetic layer, for example, oxides of Cr, Si, Ta, Al, Ti, Mg, Co, etc. are preferably used. Among them, TiO2, Cr2O3, SiO2, etc. are particularly preferred. In addition, the first magnetic layer is preferably composed of a composite oxide to which two or more oxides are added. Among them, Cr2O3-SiO2, Cr2O3-TiO2, SiO2-TiO2, etc. are particularly preferred. The first magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides.

[0464] 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.

[0465] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, Pt and no oxide. 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.

[0466] When the magnetic layer 16 is composed of a plurality of magnetic layers, a non-magnetic layer is preferably provided between adjacent magnetic layers. When the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer, a non-magnetic layer is preferably provided between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.

[0467] The non-magnetic layer arranged between adjacent magnetic layers of the magnetic layer 16 can preferably use 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.

[0468] The non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16 preferably uses an alloy material containing oxides, metal nitrides or metal carbides. 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.

[0469] The non-magnetic layer can be formed by, for example, sputtering.

[0470] In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer in which the easy magnetization axis is oriented perpendicular to the substrate surface. The magnetic layer 16 may also be an in-plane magnetic recording magnetic layer.

[0471] 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.

[0472] "Protective layer"

[0473] The protective layer 17 protects the magnetic layer 16. The protective layer 17 may be composed of one layer or multiple layers. Examples of the material of the protective layer 17 include carbon, carbon containing nitrogen, silicon carbide, and the like. As the protective layer 17, a carbon-based protective layer may be preferably used, and an amorphous carbon protective layer may be particularly preferred. If the protective layer 17 is a carbon-based protective layer, the interaction with the polar groups (especially hydroxyl groups) contained in the fluorine-containing ether compound in the lubricating layer 18 is further enhanced, and therefore, it is preferred.

[0474] The adhesion between the carbon protective layer and the lubricating layer 18 can be controlled by making the carbon protective layer hydrogenated carbon and / or carbon nitride and adjusting the hydrogen content and / or nitrogen content in the carbon protective layer. When measured by hydrogen forward scattering (HFS), the hydrogen content in the carbon protective layer is preferably 3 atomic % to 20 atomic %. In addition, the nitrogen content in the carbon protective layer is preferably 4 atomic % to 15 atomic % when measured by X-ray photoelectron spectroscopy (XPS).

[0475] The hydrogen and / or nitrogen contained in the carbon-based protective layer need not be uniformly contained in the entire carbon-based protective layer. The carbon-based protective layer is preferably set as a composition gradient layer containing nitrogen on the lubricating layer 18 side of the protective layer 17 and hydrogen 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.

[0476] The protective layer 17 preferably has a thickness of 1 nm to 7 nm. When the protective layer 17 has a thickness of 1 nm or more, sufficient performance as the protective layer 17 can be obtained. When the protective layer 17 has a thickness of 7 nm or less, it is preferred from the perspective of reducing the thickness of the protective layer 17.

[0477] As a film-forming method of the protective layer 17, a sputtering method using a carbon-containing target, a CVD (chemical vapor deposition) method using a hydrocarbon raw material such as ethylene and toluene, an IBD (ion beam deposition) method, or the like can be used.

[0478] When a carbon-based protective layer is formed as the protective layer 17, for example, the 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 preferred 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.

[0479] "Lubricating layer"

[0480] 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.

[0481] like Figure 1 As shown, the lubricating layer 18 is formed in contact with the protective layer 17. The lubricating layer 18 is formed by applying the lubricant for a magnetic recording medium of the above-mentioned embodiment onto the protective layer 17. Therefore, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.

[0482] When the protective layer 17 disposed under the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 is particularly strongly bonded to the protective layer 17. As a result, even if the lubricating layer 18 is thin, it is easy to obtain a magnetic recording medium 10 having a surface covered with the protective layer 17 at a high coverage rate, and the surface contamination of the magnetic recording medium 10 can be effectively prevented.

[0483] The average film thickness of the lubricating layer 18 is preferably , more preferably If the average film thickness of the lubricating layer 18 is 0.5 nm or more, the lubricating layer 18 will not be island-shaped or mesh-shaped but will be formed with a uniform film thickness. Therefore, the surface of the protective layer 17 can be coated with the lubricating layer 18 at a high coverage rate. In addition, by setting the average film thickness of the lubricating layer 18 to 2.0 nm or less, the lubricating layer 18 can be sufficiently thinned, and the floating amount of the magnetic head can be sufficiently reduced.

[0484] "Method for forming a lubricating layer"

[0485] Examples of a method for forming the lubricating layer 18 include a method of preparing a magnetic recording medium in the manufacturing process 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.

[0486] The lubricating layer-forming solution can be 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 solution having a viscosity and a concentration suitable for a coating method.

[0487] Examples of the solvent used in the lubricating layer-forming solution include fluorine-based solvents such as Batler (registered trademark) XF (trade name, manufactured by DuPont Mitsui Fluorochemicals Co., Ltd.) and Asahicrine (registered trademark) AE-3000 (trade name, manufactured by AGC Corporation).

[0488] The coating method of the lubricating layer forming solution is not particularly limited, and examples thereof include spin coating, spray coating, paper coating, and dipping.

[0489] 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 device. Then, the substrate 11 is pulled out of the dipping tank at a predetermined speed. Thus, the lubricating layer forming solution is applied to the surface of the substrate 11 on the protective layer 17.

[0490] 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.

[0491] In the present embodiment, it is preferable to perform heat treatment on the substrate 11 formed with the lubricating layer 18. 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.

[0492] The heat treatment temperature is preferably set to 100° C. to 180° C., and more preferably set to 100° C. to 160° C. If the heat treatment temperature is 100° C. or higher, the effect of improving the adhesion between the lubricating layer 18 and the protective layer 17 can be fully 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 set to 10 minutes to 120 minutes.

[0493] In this 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.

[0494] 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. Even if the lubricating layer 18 has a thin film thickness, it has good corrosion resistance and a good adhesion inhibition effect. Therefore, the reliability, especially corrosion resistance, adhesion inhibition, and durability of the magnetic recording medium 10 of the present embodiment are excellent. Therefore, the magnetic recording medium 10 of the present embodiment can help reduce the magnetic spacing, can reduce the floating amount of the magnetic head (for example, less than 10nm), and can work stably for a long time even in a harsh environment accompanied by diversified 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.

[0495] Example

[0496] The present invention will be described in more detail below by way of examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

[0497] [Example 1]

[0498] The compound represented by the above formula (AA) is obtained by the method shown below.

[0499] Under nitrogen atmosphere, add HOCH2CF2O (CF2CF2O) into a 100 mL eggplant flask. h (CF2O) i12.5 g of 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), 2.70 g of a compound represented by the above formula (6-1) (first raw material compound), and 12 mL of tert-butanol were stirred at room temperature until uniform to form a mixture. 1.10 g of potassium tert-butoxide was added to the mixture, and the mixture was stirred at 70°C for 16 hours to react.

[0500] The compound represented by formula (6-1) is prepared by the method represented by formula (7-1). That is, the 1,2-diol site of 1,2,4-butanetriol is protected with acetone. Then, the hydroxyl group of the obtained compound is reacted with epibromohydrin represented by formula (8-1) to synthesize the compound.

[0501] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel added with 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 7.21 g of the compound represented by the following formula (10-1) as an intermediate compound 1.

[0502]

[0503] Rf1 in the formula (10-1) is the PFPE chain represented by the above formula (5-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0504] Next, 7.21 g of the compound represented by formula (10-1) obtained as intermediate compound 1, 0.55 g of epibromohydrin (second raw material compound) represented by formula (8-1) and 10 mL of tert-butyl alcohol were added to a 100 mL eggplant-shaped flask under a nitrogen atmosphere, and stirred at room temperature until uniform. 0.72 g of potassium tert-butylate was added to the uniform liquid, and the mixture was stirred at 70° C. for 23 hours to react.

[0505] The reaction solution obtained after the reaction was returned to room temperature, 10 g of a 10% hydrogen chloride·methanol solution (hydrogen chloride-methanol reagent (5-10%), manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 25 mL of a saturated sodium bicarbonate aqueous solution, and extracted twice with 50 mL of ethyl acetate. The organic layer was washed with 25 mL of brine, 25 mL of saturated sodium bicarbonate water, and 25 mL of brine in sequence, 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 3.58 g of compound (AA) (the two Rf1 in formula (AA) are PFPE chains represented by the above formula (5-1), and 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).

[0506] The obtained compound (AA) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0507] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(8H)

[0508] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0509] [Example 2]

[0510] The compound represented by the above formula (AB) is obtained by the method shown below.

[0511] The same operations as in Example 1 were performed except that the compound represented by formula (6-2) (first raw material compound) was used instead of the compound represented by formula (6-1), thereby obtaining 3.61 g of compound (AB) (the two Rf1 in formula (AB) are PFPE chains represented by the above formula (5-1); 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).

[0512] The compound represented by formula (6-2) is synthesized by protecting the 1,2-diol site of 1,2,6-hexanetriol with acetone and then reacting the hydroxyl group at the 6-position with epibromohydrin.

[0513] The obtained compound (AB) is subjected to 1 H-NMR and 19The structure was identified by the following results from F-NMR measurement.

[0514] 1 H-NMR (acetone-D6): δ[ppm]=1.40-1.85(12H), 3.40-3.85(32H), 3.85-4.10(8H)

[0515] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0516] [Example 3]

[0517] The compound represented by the above formula (AC) is obtained by the method shown below.

[0518] The same operations as in Example 1 were performed except that the compound represented by formula (6-4) (first raw material compound) was used instead of the compound represented by formula (6-1), thereby obtaining 3.53 g of compound (AC) (the two Rf1 in formula (AC) are PFPE chains represented by the above formula (5-1), and 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).

[0519] The compound represented by formula (6-4) is prepared by the method shown below. That is, acetone is used to protect the 1,2-diol site of 1,2,4-butanetriol. Then, the hydroxyl group at the 4-position is brominated and reacted with 3-butene-1-ol. The vinyl group of the compound thus obtained is oxidized using mCPBA (meta-chloroperbenzoic acid). Through the above steps, the compound represented by formula (6-4) is synthesized.

[0520] The obtained compound (AC) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0521] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(32H), 3.85-4.10(8H)

[0522] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0523] [Example 4]

[0524] The compound represented by the above formula (AD) is obtained by the method shown below.

[0525] The same operations as in Example 1 were performed except that the compound represented by formula (6-5) (the first raw material compound) was used instead of the compound represented by formula (6-1), to obtain 3.67 g of compound (AD) (the two Rf1 in formula (AD) are PFPE chains represented by the above formula (5-1), and 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).

[0526] The compound represented by formula (6-5) is prepared by the method represented by formula (7-2). That is, 3-butene-1-ol is reacted with a halogen compound obtained by brominating the hydroxyl group of p-sorbitol (2,2-dimethyl-1,3-dioxolane-4-methanol), and the vinyl group of the obtained compound is oxidized using mCPBA to synthesize the compound.

[0527] The obtained compound (AD) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0528] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(8H)

[0529] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0530] [Example 5]

[0531] The compound represented by the above formula (AE) is obtained by the method shown below.

[0532] The same operations as in Example 1 were performed except that the compound represented by formula (6-6) (the first raw material compound) was used instead of the compound represented by formula (6-1), to obtain 3.52 g of compound (AE) (the two Rf1 in formula (AE) are PFPE chains represented by the above formula (5-1), and 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).

[0533] The compound represented by formula (6-6) is synthesized by reacting 5-hexen-1-ol with a halogen compound obtained by brominating the hydroxyl group of p-sorbital, and oxidizing the vinyl group of the obtained compound using mCPBA.

[0534] The obtained compound (AE) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0535] 1 H-NMR (acetone-D6): δ[ppm]=1.40-1.85(12H), 3.40-3.85(32H), 3.85-4.10(8H)

[0536] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0537] [Example 6]

[0538] The compound represented by the above formula (AF) is obtained by the method shown below.

[0539] The same operations as in Example 1 were performed except that the compound represented by formula (6-8) (the first raw material compound) was used instead of the compound represented by formula (6-1), to obtain 3.43 g of compound (AF) (the two Rf1 in formula (AF) are PFPE chains represented by the above formula (5-1), and 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).

[0540] The compound represented by formula (6-8) is prepared by the method shown below. That is, the epoxy group of 1,2-epoxy-5-hexene is ring-opened using dilute sulfuric acid. The 1,2-diol site of the generated compound is protected using acetone. Then, the vinyl group of the obtained compound is oxidized using mCPBA to synthesize.

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

[0542] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(24H), 3.85-4.10(8H)

[0543] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0544] [Example 7]

[0545] The compound represented by the above formula (AG) is obtained by the method shown below.

[0546] Except that the compound represented by formula (6-9) (first raw material compound) was used instead of the compound represented by formula (6-1), the same operations as in Example 1 were carried out to obtain 3.15 g of compound (AG) (the two Rf1 in formula (AG) are PFPE chains represented by the above formula (5-1), and 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).

[0547] The compound represented by formula (6-9) is prepared by the method shown below. That is, one vinyl group of 1,7-octadiene is oxidized using mCPBA. The epoxy group thus produced is ring-opened using dilute sulfuric acid. The 1,2-diol site of the generated compound is protected using acetone. Then, the vinyl group of the obtained compound is oxidized using mCPBA to synthesize.

[0548] The obtained compound (AG) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0549] 1 H-NMR (acetone-D6): δ[ppm]=1.40-1.85(16H), 3.40-3.85(24H), 3.85-4.10(8H)

[0550] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0551] [Example 8]

[0552] The compound represented by the above formula (AH) is obtained by the method shown below.

[0553] The same operations as in Example 1 were performed except that the compound represented by formula (6-10) (the first raw material compound) was used instead of the compound represented by formula (6-1), to obtain 3.91 g of compound (AH) (the two Rf1s in formula (AH) are PFPE chains represented by the above formula (5-1); 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).

[0554] The compound represented by formula (6-10) is prepared by the method represented by formula (7-3). That is, one hydroxyl group of 1,3-propylene glycol is reacted with a halogen compound obtained by brominating the hydroxyl group of p-sorbital. Then, the hydroxyl group of the generated alcohol compound is reacted with epibromohydrin represented by formula (8-1) to synthesize the compound.

[0555] The obtained compound (AH) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0556] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(40H), 3.85-4.10(8H)

[0557] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0558] [Example 9]

[0559] The compound represented by the above formula (AI) is obtained by the method shown below.

[0560] The same operations as in Example 1 were performed except that the compound represented by formula (6-11) (the first raw material compound) was used instead of the compound represented by formula (6-1), to obtain 3.72 g of compound (AI) (the two Rf1 in formula (AI) are PFPE chains represented by the above formula (5-1), and 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).

[0561] The compound represented by formula (6-11) is prepared by the following method. That is, one hydroxyl group of 2,2-dimethyl-1,3-propanediol is reacted with a halogen compound obtained by brominating the hydroxyl group of p-sorbital. Then, the hydroxyl group of the generated alcohol compound is reacted with epibromohydrin to synthesize the compound.

[0562] The obtained compound (AI) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0563] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.25(12H), 3.40-3.85(40H), 3.85-4.10(8H)

[0564] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0565] [Example 10]

[0566] The compound represented by the above formula (AJ) is obtained by the method shown below.

[0567] Except that the compound represented by formula (6-12) (the first raw material compound) was used instead of the compound represented by formula (6-1), the same operations as in Example 1 were carried out to obtain 3.43 g of compound (AJ) (the two Rf1 in formula (AJ) are PFPE chains represented by the above formula (5-1), and 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).

[0568] The compound represented by formula (6-12) is prepared by the following method. That is, one hydroxyl group of 1,4-butanediol is reacted with a halogen compound obtained by brominating the hydroxyl group of p-sorbital, and then the hydroxyl group of the generated alcohol compound is reacted with epibromohydrin.

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

[0570] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(40H), 3.85-4.10(8H)

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

[0572] [Example 11]

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

[0574] Except that the compound represented by formula (6-13) (the first raw material compound) was used instead of the compound represented by formula (6-1), the same operations as in Example 1 were carried out to obtain 3.61 g of compound (AK) (the two Rf1 in formula (AK) are PFPE chains represented by the above formula (5-1), and 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).

[0575] The compound represented by formula (6-13) is prepared by the following method. That is, one hydroxyl group of 2,3-dimethyl-1,4-butanediol is reacted with a halogen compound obtained by brominating the hydroxyl group of p-sorbital. Then, the hydroxyl group of the generated alcohol compound is reacted with epibromohydrin to synthesize the compound.

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

[0577] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.25(12H), 1.65-1.85(4H), 3.40-3.85(40H), 3.85-4.10(8H)

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

[0579] [Example 12]

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

[0581] Except that the compound represented by formula (6-15) (the first raw material compound) was used instead of the compound represented by formula (6-1), the same operations as in Example 1 were carried out to obtain 4.21 g of compound (AL) (the two Rf1 in formula (AL) are PFPE chains represented by the above formula (5-1), and 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).

[0582] The compound represented by formula (6-15) is prepared by the following method. That is, one hydroxyl group of 2,2,3,3-tetrafluoro-1,4-butanediol is reacted with a halogen compound obtained by brominating the hydroxyl group of p-sorbital, and then the hydroxyl group of the generated alcohol compound is reacted with epibromohydrin to synthesize the compound.

[0583] The obtained compound (AL) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0584] 1 H-NMR (acetone-D6): δ[ppm]=3.40-3.85(32H), 3.85-4.10(16H)

[0585] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F), -128.5~130.0(8F)

[0586] [Example 13]

[0587] The compound represented by the above formula (AM) is obtained by the method shown below.

[0588] Under nitrogen atmosphere, add HOCH2CF2O (CF2CF2O) into a 100 mL eggplant flask. h (CF2O) i 15 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), 4.50 g of 1-bromo-4-pentene and 30 mL of N,N-dimethylformamide were stirred at room temperature until uniform to form a mixture. 1.20 g of sodium hydride (purity 60%, containing mineral oil) was added to the mixture, and the mixture was stirred at 70°C for 16 hours to react.

[0589] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel added with 50 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 6.81 g of a compound represented by the following formula (10-2) as an intermediate compound 1c.

[0590]

[0591] Rf1 in the formula (10-2) is the PFPE chain represented by the above formula (5-1). In Rf1, h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4.5.

[0592] Next, 6.81 g of the compound represented by formula (10-2) obtained as the intermediate compound 1c, 0.58 g of epibromohydrin and 10 mL of tert-butyl alcohol were added to a 100 mL eggplant-shaped flask under a nitrogen atmosphere, and stirred at room temperature until uniform. 0.76 g of potassium tert-butylate was added to the uniform liquid, and the mixture was stirred at 70° C. for 23 hours to react.

[0593] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel added with 50 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 4.85 g of a compound represented by the following formula (10-3) as an intermediate compound.

[0594]

[0595] The two Rf1 in the formula (10-3) are PFPE chains represented by the above formula (5-1). Of the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0596] Next, 4.85 g of the compound represented by formula (10-3) obtained as an intermediate compound, 20 mL of dichloromethane, and 2.45 g of mCPBA (purity 73%, containing water) were added to a 100 mL eggplant flask under a nitrogen atmosphere, and the mixture was stirred at room temperature for 16 hours to react.

[0597] To the reaction solution obtained after the reaction, 50 mL of an aqueous solution of 2.50 g of sodium sulfite was added to inactivate the excess mCPBA. After the generated solid was separated by filtration, it was transferred to a separatory funnel and extracted 3 times with 100 mL of dichloromethane. The organic layer was washed with water 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 4.14 g of a compound represented by the following formula (10-4) as an intermediate compound.

[0598]

[0599] The two Rf1s in the formula (10-4) are PFPE chains represented by the above formula (5-1). Of the two Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0600] Next, 4.14 g of the compound represented by the formula (10-4) obtained above as an intermediate compound, 20 mL of acetone, and 20 mL of 10% dilute sulfuric acid were added to a 100 mL eggplant flask under a nitrogen atmosphere, and the mixture was stirred at room temperature for 16 hours to react.

[0601] After the reaction, 20 mL of saturated sodium bicarbonate aqueous solution was added to the reaction solution obtained for neutralization, and the generated solid was separated by filtration. Then, it was transferred to a separatory funnel and extracted 3 times with 100 mL of ethyl acetate. The organic layer was washed with water 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 3.63 g of compound (AM) (the 2 Rf1 in formula (AM) are PFPE chains represented by the above formula (5-1), and among the 2 Rf1, h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4.5).

[0602] The obtained compound (AM) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0603] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(20H), 3.85-4.10(8H)

[0604] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0605] [Example 14]

[0606] The compound represented by the above formula (AN) is obtained by the method shown below.

[0607] (First reaction)

[0608] The same operation as in the first reaction of Example 1 was carried out to obtain 7.25 g of the compound represented by the above formula (10-1) as an intermediate compound 1a.

[0609] (Second reaction)

[0610] The same operation as the first reaction of Example 1 was carried out except that the compound represented by formula (6-5) (first raw material compound) was used instead of the compound represented by formula (6-1) to obtain 7.19 g of a compound represented by the following formula (10-5) as an intermediate compound 1b.

[0611]

[0612] Rf1 in the formula (10-5) is the PFPE chain represented by the above formula (5-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0613] Next, 7.25 g of the compound represented by formula (10-1) obtained as the intermediate compound 1a, 4.50 g of epibromohydrin represented by formula (8-1) (second raw material compound), and 30 mL of N,N-dimethylformamide were added to a 100 mL eggplant-shaped flask under a nitrogen atmosphere, and stirred at room temperature until uniform to form a mixture. 0.25 g of sodium hydride (purity 60%, containing mineral oil) was added to the mixture, and stirred at room temperature for 16 hours to react.

[0614] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel added with 50 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 4.81 g of a compound represented by the following formula (10-6) as an intermediate compound 2a.

[0615]

[0616] Rf1 in the formula (10-6) is the PFPE chain represented by the above formula (5-1). In Rf1, h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4.5.

[0617] Next, in a nitrogen atmosphere, 4.81 g of the compound represented by formula (10-6) obtained as the intermediate compound 2a, 7.19 g of the compound represented by formula (10-5) as the intermediate compound 1b, and 20 mL of tert-butanol were added to a 100 mL eggplant-shaped flask, and stirred at room temperature until uniform to form a mixture. 0.61 g of potassium tert-butoxide was added to the mixture, and stirred at 70°C for 16 hours to react.

[0618] 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 aqueous solution, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine in sequence, 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 4.21 g of compound (AN) (Rf1 in formula (AN) is the PFPE chain represented by the above formula (5-1), and in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

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

[0620] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(8H)

[0621] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0622] [Example 15]

[0623] The compound represented by the above formula (AO) is obtained by the method shown below.

[0624] Except that the compound represented by formula (6-17) (the third raw material compound) is used instead of the compound represented by formula (6-5), the same operations as in Example 14 are carried out to obtain 3.51 g of compound (AO) (the two Rf1 in formula (AO) are PFPE chains represented by the above formula (5-1), and 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).

[0625] The compound represented by the formula (6-17) is synthesized by protecting the hydroxyl group of ethylene glycol monoallyl ether with dihydropyran and then oxidizing the vinyl group with mCPBA.

[0626] The obtained compound (AO) is subjected to 1 H-NMR and19 The structure was identified based on the following results from F-NMR measurement.

[0627] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(30H), 3.85-4.10(8H)

[0628] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0629] [Example 16]

[0630] The compound represented by the above formula (AP) is obtained by the method shown below.

[0631] Except that the compound represented by formula (6-18) (the third raw material compound) is used instead of the compound represented by formula (6-5), the same operations as in Example 14 are carried out to obtain 3.66 g of compound (AP) (the two Rf1 in formula (AP) are PFPE chains represented by the above formula (5-1), and 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).

[0632] The compound represented by formula (6-18) is prepared by the following method. That is, epichlorohydrin is reacted with 3-butene-1-ol in a 2-fold molar amount thereof. Then, the hydroxyl group generated by the reaction is protected with dihydropyran and one vinyl group is oxidized with mCPBA to synthesize the compound.

[0633] The obtained compound (AP) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0634] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(33H), 3.85-4.10(8H), 5.20-5.80(3H)

[0635] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0636] [Example 17]

[0637] The compound represented by the above formula (AQ) is obtained by the method shown below.

[0638] Except that the compound represented by formula (6-19) (the third raw material compound) was used instead of the compound represented by formula (6-5), the same operations as in Example 14 were carried out to obtain 3.42 g of compound (AQ) (the two Rf1 in formula (AQ) are PFPE chains represented by the above formula (5-1), and 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).

[0639] The compound represented by the formula (6-19) is synthesized by reacting the hydroxyl group of 2-acetamidoethanol with epibromohydrin.

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

[0641] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 1.90(3H), 3.40-3.85(29H), 3.85-4.10(8H), 6.70-6.80(1H)

[0642] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0643] [Example 18]

[0644] The compound represented by the above formula (AR) is obtained by the method shown below.

[0645] Except that the compound represented by formula (6-20) (the third raw material compound) is used instead of the compound represented by formula (6-5), the same operations as in Example 14 are carried out to obtain 3.78 g of compound (AR) (the two Rf1 in formula (AR) are PFPE chains represented by the above formula (5-1), and 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).

[0646] The compound represented by the formula (6-20) is synthesized by reacting the hydroxyl group of 3-cyanopropanol with epibromohydrin.

[0647] The obtained compound (AR) was subjected to 1 H-NMR and 19The structure was identified based on the following results from F-NMR measurement.

[0648] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 1.90-2.00(2H), 3.40-3.85(27H), 3.85-4.10(8H)

[0649] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0650] [Example 19]

[0651] The compound represented by the above formula (AS) is obtained by the method shown below.

[0652] Except that the compound represented by formula (6-21) (the third raw material compound) was used instead of the compound represented by formula (6-5), the same operations as in Example 14 were carried out to obtain 3.44 g of compound (AS) (the two Rf1 in formula (AS) are PFPE chains represented by the above formula (5-1), and 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).

[0653] The compound represented by the formula (6-21) is synthesized by protecting the hydroxyl group of 3-buten-1-ol with dihydropyran and then oxidizing the vinyl group with mCPBA.

[0654] The obtained compound (AS) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0655] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(26H), 3.85-4.10(8H)

[0656] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0657] [Example 20]

[0658] The compound represented by the above formula (AT) is obtained by the method shown below.

[0659] Except that the compound represented by formula (6-22) (the third raw material compound) was used instead of the compound represented by formula (6-5), the same operations as in Example 14 were carried out to obtain 3.32 g of compound (AT) (the two Rf1 in formula (AT) are PFPE chains represented by the above formula (5-1), and 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).

[0660] The compound represented by the formula (6-22) is synthesized by protecting the two hydroxyl groups of 3-allyloxy-1,2-propanediol with dihydropyran and then oxidizing the vinyl groups with mCPBA.

[0661] The obtained compound (AT) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0662] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(32H), 3.85-4.10(8H)

[0663] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0664] [Example 21]

[0665] The compound represented by the above formula (BA) is obtained by the method shown below.

[0666] The same operations as in Example 1 were carried out except that the compound represented by formula (8-2) (the second raw material compound) was used instead of epibromohydrin, to obtain 3.21 g of compound (BA) (the two Rf1 in formula (BA) are PFPE chains represented by the above formula (5-1), and 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).

[0667] The obtained compound (BA) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0668] 1H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(32H), 3.85-4.10(8H)

[0669] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0670] [Example 22]

[0671] The compound represented by the above formula (BB) is obtained by the method shown below.

[0672] The same operation as in Example 1 was carried out except that the compound represented by formula (8-3) (the second raw material compound) was used instead of epibromohydrin, to obtain 2.96 g of compound (BB) (the two Rf1 in formula (BB) are PFPE chains represented by the above formula (5-1), and 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).

[0673] The obtained compound (BB) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0674] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(38H), 3.85-4.10(8H)

[0675] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0676] [Example 23]

[0677] The compound represented by the above formula (BC) is obtained by the method shown below.

[0678] The same operation as in Example 1 was carried out except that the compound represented by formula (8-4) (the second raw material compound) was used instead of epibromohydrin, to obtain 3.04 g of compound (BC) (the two Rf1 in formula (BC) are PFPE chains represented by the above formula (5-1), and 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).

[0679] The obtained compound (BC) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0680] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(34H), 3.85-4.10(8H)

[0681] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0682] [Example 24]

[0683] The compound represented by the above formula (BD) is obtained by the method shown below.

[0684] The same operations as in Example 1 were performed except that the compound represented by formula (8-5) (the second raw material compound) was used instead of epibromohydrin, to obtain 3.43 g of compound (BD) (the two Rf1 in formula (BD) are PFPE chains represented by the above formula (5-1); 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).

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

[0686] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(34H), 3.85-4.10(8H)

[0687] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0688] [Example 25]

[0689] The compound represented by the above formula (BE) is obtained by the method shown below.

[0690] Except that the compound represented by formula (8-6) (the second raw material compound) was used instead of epibromohydrin, the same operations as in Example 1 were carried out to obtain 3.61 g of compound (BE) (the two Rf1 in formula (BE) are PFPE chains represented by the above formula (5-1), and 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).

[0691] The compound represented by formula (8-6) is synthesized by reacting 3-butene-1-ol with epibromohydrin and then oxidizing the vinyl group with mCPBA.

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

[0693] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(38H), 3.85-4.10(8H)

[0694] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0695] [Example 26]

[0696] The compound represented by the above formula (BF) is obtained by the method shown below.

[0697] Except that the compound represented by formula (8-7) (the second raw material compound) was used instead of epibromohydrin, the same operations as in Example 1 were carried out to obtain 3.20 g of compound (BF) (the two Rf1 in formula (BF) are PFPE chains represented by the above formula (5-1), and 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).

[0698] The compound represented by formula (8-7) is prepared by the method represented by formula (9-2). That is, the epibromohydrin represented by formula (8-1) is reacted with 2 times the molar amount of 3-butene-1-ol, the generated hydroxyl group is protected with dihydropyran, and the vinyl groups at both ends are oxidized with mCPBA to synthesize.

[0699] The obtained compound (BF) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0700] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(44H), 3.85-4.10(8H)

[0701] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0702] [Example 27]

[0703] The compound represented by the above formula (BG) is obtained by the method shown below.

[0704] Except that the compound represented by formula (8-8) (the second raw material compound) was used instead of epibromohydrin, the same operations as in Example 1 were carried out to obtain 3.41 g of compound (BG) (the two Rf1 in formula (BG) are PFPE chains represented by the above formula (5-1), and 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).

[0705] The compound represented by formula (8-8) was prepared by the method represented by formula (9-1), that is, by reacting 1,4-butanediol with a 2-fold molar amount of epibromohydrin represented by formula (8-1).

[0706] The obtained compound (BG) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0707] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(42H), 3.85-4.10(8H)

[0708] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0709] [Example 28]

[0710] The compound represented by the above formula (BH) is obtained by the method shown below.

[0711] The same operations as in Example 1 were carried out except that the compound represented by formula (8-9) (the second raw material compound) was used instead of epibromohydrin, to obtain 3.37 g of compound (BH) (the two Rf1s in formula (BH) are PFPE chains represented by the above formula (5-1); 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).

[0712] The compound represented by formula (8-9) is synthesized by reacting 2,2-dimethyl-1,3-propanediol with a 2-fold molar amount of epibromohydrin.

[0713] The obtained compound (BH) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0714] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.25(6H), 1.65-1.85(4H), 3.40-3.85(42H), 3.85-4.10(8H)

[0715] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0716] [Example 29]

[0717] The compound represented by the above formula (BI) is obtained by the method shown below.

[0718] The same operations as in Example 1 were performed except that the compound represented by formula (8-10) (the second raw material compound) was used instead of epibromohydrin to obtain 3.58 g of compound (BI) (the two Rf1s in formula (BI) are PFPE chains represented by the above formula (5-1); 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).

[0719] The compound represented by formula (8-10) is synthesized by reacting 2,3-dimethyl-1,4-butanediol with a 2-fold molar amount of epibromohydrin.

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

[0721] 1H-NMR (acetone-D6): δ[ppm]=1.20-1.25(6H), 1.65-1.85(6H), 3.40-3.85(42H), 3.85-4.10(8H)

[0722] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0723] [Example 30]

[0724] The compound represented by the above formula (BJ) is obtained by the method shown below.

[0725] The same operations as in Example 1 were performed except that the compound represented by formula (8-11) (the second raw material compound) was used instead of epibromohydrin to obtain 3.97 g of compound (BJ) (the two Rf1s in formula (BJ) are PFPE chains represented by the above formula (5-1); 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).

[0726] The compound represented by formula (8-11) is synthesized by reacting 2,2,3,3-tetrafluoro-1,4-butanediol with a 2-fold molar amount of epibromohydrin.

[0727] The obtained compound (BJ) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0728] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(38H), 3.85-4.10(12H)

[0729] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F), -128.5~130.0(4F)

[0730] [Example 31]

[0731] The compound represented by the above formula (BK) is obtained by the method shown below.

[0732] Using HOCH2CF2CF2O (CF2CF2CF2O)j A compound represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) is substituted for HOCH2CF2O (CF2CF2O) h (CF2O) i The compound represented by CF2CH2OH was treated with the same operation as in Example 1 to obtain 3.48 g of compound (BK) (the two Rf2 in formula (BK) are PFPE chains represented by the above formula (5-2), and among the two Rf2, j representing the average degree of polymerization is 4.5).

[0733] The obtained compound (BK) was subjected to 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]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(4H)

[0735] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0736] [Example 32]

[0737] The compound represented by the above formula (BL) is obtained by the method shown below.

[0738] Use HOCH2CF2CF2CF2O (CF2CF2CF2CF2O) k A compound represented by CF2CF2CF2CH2OH (where k representing the average degree of polymerization is 3.0) (number average molecular weight 1000, molecular weight distribution 1.1) instead of HOCH2CF2O (CF2CF2O) h (CF2O) i The same operation as in Example 1 was carried out except that the compound represented by CF2CH2OH was used to obtain 3.38 g of compound (BL) (Rf3 in formula (BL) is the PFPE chain represented by the above formula (5-3), and in Rf3, k representing the average degree of polymerization is 3.0).

[0739] The obtained compound (BL) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0740] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(4H)

[0741] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(32F), -122.5(8F), -126.0(24F), -129.0~-128.0(8F)

[0742] [Example 33]

[0743] The compound represented by the above formula (CA) is obtained by the method shown below.

[0744] Make HOCH2CF2O(CF2CF2O) 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) reacts with epibromohydrin (the second raw material compound) to obtain a compound represented by the following formula (10-7) as an intermediate compound 3a.

[0745]

[0746] Rf1 in the formula (10-7) is the PFPE chain represented by the above formula (5-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0747] Next, in the reaction between the compound represented by formula (10-1) in Example 1 and epibromohydrin, the same operations as in Example 1 were performed except that the compound represented by formula (10-7) as the intermediate compound 3a was used instead of epibromohydrin to obtain 4.75 g of compound (CA) (the three Rf1s in formula (CA) are PFPE chains represented by the above formula (5-1); 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).

[0748] The obtained compound (CA) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0749] 1H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(38H), 3.85-4.10(12H)

[0750] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0751] [Example 34]

[0752] The compound represented by the above formula (CB) is obtained by the method shown below.

[0753] When preparing the compound represented by formula (10-1) in Example 1, the compound represented by formula (6-5) (first raw material compound) was used instead of the compound represented by formula (6-1). Except for this, the same operations as in Example 33 were performed to obtain 4.51 g of compound (CB) (the three Rf1 in formula (CB) are PFPE chains represented by the above formula (5-1); 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).

[0754] The obtained compound (CB) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0755] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(38H), 3.85-4.10(12H)

[0756] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0757] [Example 35]

[0758] The compound represented by the above formula (CC) is obtained by the method shown below.

[0759] In Example 1, when preparing the compound represented by formula (10-1), the compound represented by formula (6-8) (first raw material compound) was used instead of the compound represented by formula (6-1). Except for this, the same operations as in Example 33 were carried out to obtain 4.15 g of compound (CC) (the three Rf1 in formula (CC) are PFPE chains represented by the above formula (5-1); 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).

[0760] The obtained compound (CC) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0761] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(12H), 3.40-3.85(30H), 3.85-4.10(12H)

[0762] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0763] [Example 36]

[0764] The compound represented by the above formula (CD) is obtained by the method shown below.

[0765] When preparing the compound represented by formula (10-1) in Example 1, the compound represented by formula (6-10) (the first raw material compound) was used instead of the compound represented by formula (6-1). Except for this, the same operations as in Example 33 were performed to obtain 4.36 g of compound (CD) (the three Rf1 in formula (CD) are PFPE chains represented by the above formula (5-1); 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).

[0766] The obtained compound (CD) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0767] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(46H), 3.85-4.10(12H)

[0768] 19F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0769] [Example 37]

[0770] The compound represented by the above formula (CE) was obtained by the method shown below.

[0771] Make HOCH2CF2O(CF2CF2O) 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) is reacted with allyl glycidyl ether. After protecting the hydroxyl group of the compound generated by the reaction with dihydropyran, the double bond of the compound is oxidized with mCPBA, thereby obtaining a compound represented by the following formula (10-8) as an intermediate compound 3a.

[0772]

[0773] Rf1 in the formula (10-8) is the PFPE chain represented by the above formula (5-1), in Rf1, h representing the average degree of polymerization represents 4.5, i representing the average degree of polymerization represents 4.5, and THP represents tetrahydropyranyl.

[0774] Next, in the reaction between the compound represented by formula (10-1) in Example 1 and epibromohydrin, the same operations as in Example 1 were performed except that the compound represented by formula (10-8) as the intermediate compound 3a was used instead of epibromohydrin to obtain 4.56 g of compound (CE) (the three Rf1s in formula (CE) are PFPE chains represented by the above formula (5-1); 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).

[0775] The obtained compound (CE) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0776] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(50H), 3.85-4.10(12H)

[0777] 19F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0778] [Example 38]

[0779] The compound represented by the above formula (CF) is obtained by the method shown below.

[0780] Using 1,2-epoxy-5-hexene instead of allyl glycidyl ether, the same operations as in Example 37 were carried out to obtain 3.87 g of compound (CF) (the three Rf1 in formula (CF) are PFPE chains represented by the above formula (5-1), and 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).

[0781] The obtained compound (CF) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0782] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(12H), 3.40-3.85(42H), 3.85-4.10(12H)

[0783] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0784] [Example 39]

[0785] The compound represented by the above formula (DA) is obtained by the method shown below.

[0786] Using HOCH2CF2O (CF2CF2O) h (CF2O) i A compound represented by CF2CH2OH (wherein h representing the average degree of polymerization is 7.0 and i representing the average degree of polymerization is 0) replaces HOCH2CF2O (CF2CF2O) h (CF2O) iThe same operation as in Example 1 was carried out except that 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) was obtained to obtain 3.31 g of compound (DA) (the two Rf1 in formula (DA) are PFPE chains represented by the above formula (5-1), and among the two Rf1, h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0).

[0787] The obtained compound (DA) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0788] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(8H)

[0789] 19 F-NMR (acetone-D6): δ [ppm] = -78.5 (8F), -91.0 to -88.5 (56F)

[0790] [Example 40]

[0791] The compound represented by the above formula (DB) is obtained by the method shown below.

[0792] Except that the compound represented by formula (6-5) was used instead of the compound represented by formula (6-1), the same operations as in Example 39 were performed to obtain 3.81 g of compound (DB) (the two Rf1 in formula (DB) are PFPE chains represented by the above formula (5-1); among the two Rf1, h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0).

[0793] The obtained compound (DB) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0794] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(8H)

[0795] 19 F-NMR (acetone-D6): δ [ppm] = -78.5 (8F), -91.0 to -88.5 (56F)

[0796] [Example 41]

[0797] The compound represented by the above formula (DC) is obtained by the method shown below.

[0798] Except for using the compound represented by formula (6-5) instead of the compound represented by formula (6-1), the same operations as in Example 31 were carried out to obtain 3.61 g of compound (DC) (the two Rf2 in formula (DC) are PFPE chains represented by the above formula (5-2), and among the two Rf2, j representing the average degree of polymerization is 4.5).

[0799] The obtained compound (DC) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0800] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(32H), 3.85-4.10(4H)

[0801] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0802] [Example 42]

[0803] The compound represented by the above formula (DD) is obtained by the method shown below.

[0804] Using the compound represented by formula (8-6) (the second raw material compound) instead of epibromohydrin, the same operations as in Example 41 were carried out to obtain 3.42 g of compound (DD) (the two Rf2 in formula (DD) are PFPE chains represented by the above formula (5-2), and among the two Rf2, j representing the average degree of polymerization is 4.5).

[0805] The obtained compound (DD) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0806] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(38H), 3.85-4.10(8H)

[0807] 19F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0808] [Example 43]

[0809] The compound represented by the above formula (DE) is obtained by the method shown below.

[0810] The compound represented by formula (8-12) (the second raw material compound) was used instead of epibromohydrin, and the same operations as in Example 41 were carried out to obtain 3.71 g of compound (DE) (the two Rf2 in formula (DE) are PFPE chains represented by the above formula (5-2), and among the two Rf2, j representing the average degree of polymerization is 4.5).

[0811] The compound represented by formula (8-12) is synthesized by reacting 5-hexen-1-ol with epibromohydrin and then oxidizing the vinyl group with mCPBA.

[0812] The obtained compound (DE) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0813] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(10H), 3.40-3.85(38H), 3.85-4.10(8H)

[0814] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0815] [Example 44]

[0816] The compound represented by the above formula (DF) is obtained by the method shown below.

[0817] Under nitrogen atmosphere, add HOCH2CF2CF2O (CF2CF2CF2O) into a 100 mL eggplant flask. j12 g of a compound represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1), 1.81 g of a compound represented by the above formula (6-24), and 20 mL of N,N-dimethylformamide were stirred at room temperature until uniform to form a mixture. 5.51 g of cesium carbonate was added to the mixture, and the mixture was stirred at 50°C for 16 hours to react.

[0818] The compound represented by formula (6-24) is synthesized by protecting the 1,2-diol site of 1,2,6-hexanetriol with acetone and then reacting the 6-hydroxyl group with p-toluenesulfonyl chloride.

[0819] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel added with 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 6.04 g of a compound represented by the following formula (10-9) as an intermediate compound 1.

[0820]

[0821] Rf2 in the formula (10-9) is the PFPE chain represented by the above formula (5-2), and in Rf2, j indicating the average degree of polymerization is 4.5.

[0822] Next, 6.04 g of the compound represented by formula (10-9) obtained as intermediate compound 1, 0.45 g of the compound represented by formula (8-12) (second raw material compound), and 10 mL of tert-butanol were added to a 100 mL eggplant-shaped flask under a nitrogen atmosphere, and stirred at room temperature until uniform. 0.72 g of potassium tert-butoxide was added to the uniform liquid, and stirred at 70° C. for 23 hours to react.

[0823] The reaction solution obtained after the reaction was returned to room temperature, 10 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 25 mL of saturated sodium bicarbonate aqueous solution, and extracted twice with 50 mL of ethyl acetate. The organic layer was washed with 25 mL of brine, 25 mL of saturated sodium bicarbonate water, and 25 mL of brine in sequence, and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 3.31 g of compound (DF) (the two Rf2 in formula (DF) are PFPE chains represented by the above formula (5-2), and among the two Rf2, j representing the average degree of polymerization is 4.5).

[0824] The obtained compound (DF) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0825] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(18H), 3.40-3.85(26H), 3.85-4.10(8H)

[0826] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0827] [Example 45]

[0828] The compound represented by the above formula (DG) is obtained by the method shown below.

[0829] Except that the epibromohydrin represented by the above formula (8-1) was used instead of the compound represented by formula (8-12), and the compound represented by formula (6-25) was used instead of the compound represented by formula (6-24), the same operations as in Example 44 were carried out to obtain 3.36 g of compound (DG) (the two Rf2 in formula (DG) are PFPE chains represented by the above formula (5-2), and among the two Rf2, j representing the average degree of polymerization is 4.5).

[0830] The compound represented by formula (6-25) is synthesized by the following method. First, the hydroxyl group of 5-hexen-1-ol is protected with dihydropyran, and then the olefinic group is oxidized with m-chloroperbenzoic acid. Then, the obtained compound is reacted with sorbitol ketal, and the secondary hydroxyl group of the generated compound is protected with chloromethyl methyl ether. The compound represented by the following formula (6-25A) is acted on with an acid, and after the THP group is selectively deprotected, the primary hydroxyl group is reacted with p-toluenesulfonyl chloride to obtain the compound represented by formula (6-25).

[0831] Selective deprotection of the THP group was carried out as follows: 1.21 g (4.83 mmol) of pyridinium p-toluenesulfonate as an acid catalyst was added to a mixture of 9.09 g (24.2 mmol) of the compound represented by formula (6-25A) and a mixed solvent of 40 g of 2-propanol and 40 g of acetone, and the mixture was stirred at a reaction temperature of 55°C for 7 hours in an air atmosphere.

[0832]

[0833] The obtained compound (DG) was subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0834] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(12H), 3.40-3.85(32H), 3.85-4.10(8H)

[0835] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0836] [Example 46]

[0837] The compound represented by the above formula (DH) is obtained by the method shown below.

[0838] Using HOCH2CF2CF2O (CF2CF2CF2O) j A compound represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) is substituted for HOCH2CF2O (CF2CF2O) h (CF2O) i The compound represented by CF2CH2OH was treated with the same operation as in Example 34 to obtain 3.21 g of compound (DH) (the three Rf2 in formula (DH) are PFPE chains represented by the above formula (5-2), and among the three Rf2, j representing the average degree of polymerization is 4.5).

[0839] The obtained compound (DH) was subjected to 1 H-NMR and 19 The structure was identified by the following results from F-NMR measurement.

[0840] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(38H), 3.85-4.10(12H)

[0841] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(54F), -86.4(12F), -124.3(12F), -130.0~-129.0(27F)

[0842] The compounds (AA) to (AT), (BA) to (BL), (CA) to (CF), and (DA) to (DH) of Examples 1 to 46 obtained in this way correspond to x and R in the formula (1), respectively. 1 , R 2 , R 3 , R 4 The structures are shown in Tables 1 to 3.

[0843]

[0844]

[0845]

[0846] [Comparative Example 1]

[0847] According to the method described in Patent Document 1, a compound represented by the following formula (ZA) was synthesized.

[0848]

[0849] The two Rf1 in the formula (ZA) are PFPE chains represented by the above formula (5-1). In the two Rf1, h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0.

[0850] [Comparative Example 2]

[0851] By the method described in Patent Document 2, a compound represented by the following formula (ZB) was synthesized.

[0852]

[0853] The two Rf1 in the formula (ZB) are PFPE chains represented by the above formula (5-1). Of the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0854] [Comparative Example 3]

[0855] By the method described in Patent Document 3, a compound represented by the following formula (ZC) was synthesized.

[0856]

[0857] The two Rf1 in the formula (ZC) are PFPE chains represented by the above formula (5-1). Of the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0858] [Comparative Example 4]

[0859] According to the method described in Patent Document 4, a compound represented by the following formula (ZD) was synthesized.

[0860]

[0861] The two Rf2 in the formula (ZD) are PFPE chains represented by the above formula (5-2), and j representing the average degree of polymerization of the two Rf2 is 4.5.

[0862] [Comparative Example 5]

[0863] According to the method described in Patent Document 5, a compound represented by the following formula (ZE) was synthesized.

[0864]

[0865] The three Rf1s in the formula (ZE) are PFPE chains represented by the above formula (5-1). 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.

[0866] The number average molecular weight (Mn) of the compounds of Examples 1 to 46 and Comparative Examples 1 to 5 thus obtained was measured by the above-mentioned method. The results are shown in Tables 4 to 6.

[0867] Next, a lubricant layer forming solution was prepared by the method shown below using the compounds obtained in Examples 1 to 46 and Comparative Examples 1 to 5. Then, the lubricant layer of a magnetic recording medium was formed by the method shown below using the obtained lubricant layer forming solution, thereby obtaining magnetic recording media of Examples 1 to 46 and Comparative Examples 1 to 5.

[0868] "Lubricating layer forming solution"

[0869] The fluorinated ether compounds obtained in Examples 1 to 46 and Comparative Examples 1 to 5 were dissolved in a fluorinated solvent, Batler (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.), and the fluorinated ether compounds were applied on the protective layer at a film thickness of The mixture was diluted with Batler XF in a manner of 1:1 to prepare a lubricating layer forming solution.

[0870] "Magnetic Recording Media"

[0871] 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 made of carbon.

[0872] 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 46 and Comparative Examples 1 to 5 were applied by dipping. The dipping method was performed under the conditions of dipping speed of 10 mm / sec, dipping time of 30 sec, and pulling speed of 1.2 mm / sec.

[0873] Then, the magnetic recording medium coated with the lubricating layer forming solution is placed in a constant temperature bath, and heat treatment is performed 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.

[0874] (Film thickness measurement)

[0875] The film thickness of the lubricating layer of the magnetic recording media of Examples 1 to 41 and Comparative Examples 1 to 7 obtained in this manner was measured using a Fourier transform infrared spectrophotometer (FT-IR, trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific).

[0876] Next, the magnetic recording media of Examples 1 to 46 and Comparative Examples 1 to 5 were subjected to the following corrosion resistance test and adhesion property test. The results are shown in Tables 4 to 6.

[0877] [Corrosion resistance test]

[0878] The magnetic recording medium was exposed to a temperature of 85°C and a relative humidity of 90% for 48 hours. Then, an optical surface analysis device (Candela 7140, manufactured by Celerity Tencore Co., Ltd.) was used to count the number of corrosion spots with a diameter of more than 5 μm produced on the surface of the magnetic recording medium, and the evaluation was performed based on the following evaluation criteria.

[0879] "Evaluation criteria for corrosion resistance"

[0880] A+: The number of corrosion points is less than 100

[0881] A: The number of corrosion points is more than 100 and less than 300

[0882] B: The number of corrosion points is more than 300 and less than 500

[0883] C: The number of corrosion points is 500 or more and less than 1000

[0884] D: The number of corrosion points is more than 1000

[0885] [Adhesion characteristics test]

[0886] The magnetic recording medium and the magnetic head are mounted on a rotating frame, and the magnetic head is rotated under normal temperature and reduced pressure (about 250torr) to make the magnetic head float at a fixed point for 10 minutes. Then, the surface (the surface of the lubricating layer) on the magnetic head relative to the magnetic recording medium is analyzed using an ESCA (Electron Spectroscopy for Chemical Analysis) analysis device. The intensity (signal intensity (au)) of the peak derived from fluorine obtained by the analysis using the ESCA analysis device is used to evaluate the attachment amount of the lubricant to the magnetic head according to the evaluation criteria shown below.

[0887] "Evaluation criteria for adhesion properties"

[0888] A+: Signal strength is less than 120 (almost no attachment)

[0889] A: Signal strength is above 120 and less than 180 (very little adhesion)

[0890] B: Signal strength is 180 or more and less than 300 (small amount of adhesion)

[0891] C: Signal strength is 300 or more and less than 1000 (large amount of adhesion)

[0892] D: Signal strength is above 1000 (very high amount of adhesion)

[0893] [Comprehensive evaluation]

[0894] From the results of the corrosion resistance test and the adhesion property test, comprehensive evaluation was performed based on the following criteria.

[0895] “Comprehensive Evaluation Criteria”

[0896] A: Both the corrosion resistance test and the adhesion test were rated A+ or A

[0897] B: One of the evaluations in the corrosion resistance test and the adhesion test is B, and the other is A+, A, or B

[0898] C: One of the evaluations in the corrosion resistance test and the adhesion test is C, and the other is A+, A, B, or C

[0899] D: At least one of the evaluations in the corrosion resistance test and the adhesion test is D

[0900] Table 4

[0901]

[0902] Table 5

[0903]

[0904] Table 6

[0905]

[0906] As shown in Tables 4 to 6, R 1 and R 4 The evaluations of the corrosion resistance test and adhesion property test of the magnetic recording media of Examples 1 to 46 of the fluorinated ether compounds (AA) to (AT), (BA) to (BL), (CA) to (CF), (DA) to (DH) represented by formula (1), at least one of which is an end group represented by any one of formulas (2-1) to (2-7), were all A+, A, and B, and the comprehensive evaluation was A or B. It can be confirmed that the lubricating layer of the magnetic recording media of Examples 1 to 46 has good corrosion resistance and good adhesion suppression effect.

[0907] In particular, when R in formula (1) is used 3 is a connecting group represented by formula (4-1) and u1 and u2 are 0, R 1 and R 4 In Examples 6, 7, 12, 13, 35, and 45 of the compounds (AF), (AG), (AL), (AM), (CC), and (DG) having terminal groups represented by formula (2-3), (2-5), (2-6), and (2-7), the evaluation of the corrosion resistance test was A+, showing a good result. This confirms that the fluorine-containing ether compounds having terminal groups represented by formula (2-3), (2-5), (2-6), and (2-7) can form a lubricating layer with better corrosion resistance.

[0908] In addition, when using R in formula (1) 3 is a connecting group represented by formula (4-1) and u1 and u2 are 0, R 1 and R 4 In Examples 1 to 5, 8 to 11, 31 to 34, 36, 39 to 41, and 46 of compounds (AA) to (AE), (AH) to (AK), (BK), (BL), (CA), (CB), (CD), (DA) to (DC), and (DH) having terminal groups represented by formula (2-1), (2-2), and (2-4), the evaluation of the adhesion property test was A+, showing a good result. This confirms that the fluorine-containing ether compound having terminal groups represented by formula (2-1), (2-2), and (2-4) can form a lubricating layer with better anti-adhesion properties.

[0909] In addition, in R 1 and R 4 When a is 1 and b is 1 and R is used, 3A compound (BA) in which u1 is 0 and u2 is 1 and R 3 In Examples 21, 24, and 38 of the compound (BD) in which w is 4 and the compound (CF) in which w is 2 and the linking group represented by the formula (4-3) were evaluated as A+ in the corrosion resistance test, showing good results.

[0910] This effect is presumably due to the fact that the number of hydroxyl groups in the linking groups represented by formulae (4-1) and (4-3) is 2 or less, there is no ether bond other than at both ends of the linking groups, and the carbon atoms are not bonded to either the polar group or the ether oxygen atom, thus forming a lubricating layer having more excellent hydrophobicity.

[0911] On the other hand, as shown in Table 6, in Comparative Examples 1 to 5 using compounds (ZA) to (ZE), all evaluations of the corrosion resistance test and the adhesion property test were B, C, and D, and the comprehensive evaluation was C or D.

[0912] More specifically, although the compound (ZA) used in Comparative Example 1 and the compound (ZC) used in Comparative Example 3 have 1,2-diol structures at both ends, the terminal groups do not contain carbon atoms that are not bonded to polar groups and ether oxygen atoms. Therefore, it is considered that sufficient hydrophobicity cannot be obtained in the lubricating layer using the compounds (ZA) and (ZC), and water that causes corrosion is easily introduced, and the results of the corrosion resistance test in Comparative Examples 1 and 3 are D.

[0913] The compound (ZB) used in Comparative Example 2 and the compound (ZE) used in Comparative Example 5 contain carbon atoms that are not bonded to polar groups and ether oxygen atoms between the two hydroxyl groups respectively contained in the two end groups, and do not have a 1,2-diol structure. Therefore, in compound (ZB) and compound (ZE), all hydroxyl groups are configured to be fully separated from adjacent hydroxyl groups, and all hydroxyl groups easily interact with the protective layer. As a result, it can be considered that the intermolecular interaction of the fluorinated ether compound is small, and when the magnetic head collides with the lubricating layer, the lubricating layer easily moves from the protective layer to the magnetic head, and the evaluation of the adhesion property test of Comparative Example 2 and Comparative Example 5 becomes C.

[0914] Although the compound (ZD) used in Comparative Example 4 has a 1,2-diol structure at both ends, the end group does not contain a carbon atom that is not bonded to either the polar group or the ether oxygen atom. Therefore, in the compound (ZD), it is not possible to obtain the moderate rigidity caused by the end group containing a carbon atom that is not bonded to either the polar group or the ether oxygen atom, and the two hydroxyls constituting the 1,2-diol structure easily interact with each other within the molecule. As a result, it can be considered that in the lubricating layer using the compound (ZD), the hydroxyls in the compound are difficult to interact with each other between molecules, and when the magnetic head collides with the lubricating layer, the lubricating layer easily moves from the protective layer to the magnetic head, and the evaluation of the adhesion property test of Comparative Example 4 becomes D.

[0915] Industrial Applicability

[0916] By using the lubricant for a magnetic recording medium containing the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer which has excellent corrosion resistance and a high adhesion suppressing effect even though it is thin.

[0917] Attachment Description

[0918] 10 Magnetic Recording Media

[0919] 11 base plate

[0920] 12 Adhesion layer

[0921] 13 Soft magnetic layer

[0922] 14 First base layer

[0923] 15 Second base layer

[0924] 16 Magnetic layer

[0925] 17 Protective layer

[0926] 18 Lubrication 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 partially or completely the same, or they may be different; R 3 is a divalent linking group having 1 to 4 polar groups; when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms; R 1 and R 4 Can be the same or different; R 1 and R 4 At least one of them is a terminal group represented by the following formula (2); -OX-CH(OH)-CH2OH(2) In formula (2), X is a divalent organic group having 2 to 30 carbon atoms which may contain at least one of 1 to 2 polar groups and 1 to 3 ether oxygen atoms, and X contains at least one carbon atom which is not bonded to either the polar group or the ether oxygen atom.

2. The fluorinated ether compound according to claim 1, wherein the terminal group represented by the formula (2) is any one of the following formulas (2-1) to (2-7): In formula (2-1), a represents an integer from 1 to 8, and b represents an integer from 1 to 7; In formula (2-2), c represents an integer from 1 to 7; In formula (2-3), d represents an integer from 1 to 6; In formula (2-4), e represents an integer of 1 to 6, and e R a and R b each independently represents a hydrogen atom or a methyl group; In formula (2-5), f represents an integer from 1 to 6; In formula (2-6), g represents an integer from 1 to 6; In formula (2-7), g2 represents an integer of 1 to 6.

3. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 and R 4 Each is independently a terminal group represented by the above formula (2).

4. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 and R 4 same.

5. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 and R 4 One of them is a terminal group represented by the above formula (2), and the other is a terminal group represented by the following formula (3) and not belonging to the formula (2); In formula (3), l represents an integer of 1 to 3; l m each independently represents an integer of 1 to 6; l n each independently represents an integer of 1 to 6; in one repeating unit, at least one of m and n is 1; B represents an alkyl group which may have only one polar group, an organic group containing a carbon-carbon unsaturated bond, or a hydrogen atom.

6. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 and R 4 One of them is a terminal group represented by the above formula (2), and the other is a terminal group represented by the following formula (3-1) or (3-2); In formula (3-1), p represents an integer of 0 to 3; q represents an integer of 0 to 2; r represents an integer of 0 to 5; the total value of p and r is 1 to 5; D represents a polar group, a vinyl group, an ethynyl group, or an aromatic group which may have a substituent; In the formula (3-2), s represents an integer of 0-2, and t represents an integer of 1-5.

7. The fluorinated ether compound according to claim 1 or 2, wherein the x R in the formula (1) 3 Each independently represents a divalent linking group having 1 to 3 hydroxyl groups, oxygen atoms at both ends bonded to adjacent methylene groups, and 3 to 50 carbon atoms.

8. The fluorinated ether compound according to claim 1 or 2, wherein the x R in the formula (1) 3 Each is independently selected from any one of the linking groups represented by the following formulae (4-1) to (4-6): In formula (4-1), u1 represents an integer from 0 to 6, and u2 represents an integer from 0 to 6; wherein, At least one of u1 and u2 is 0; the oxygen atom at the left end of formula (4-1) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding; In formula (4-2), v represents an integer of 1 to 2, and the oxygen atom at the left terminal of formula (4-2) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding; In formula (4-3), w represents an integer of 0 to 6, and the oxygen atom at the left terminal of formula (4-3) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding; In formula (4-4), x1 represents an integer of 0 to 5, and x2 represents an integer of 0 to 5, wherein at least one of x1 and x2 is an integer of 1 to 5; the oxygen atom at the left terminal of formula (4-4) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding; In formula (4-5), y1 represents an integer of 1 to 5, y2 represents an integer of 1 to 5; the oxygen atom at the left terminal of formula (4-5) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding; In formula (4-6), z represents an integer of 1 to 6, and z R c and R d Each independently represents a hydrogen atom, a fluorine atom or a methyl group; the oxygen atom at the left terminal of formula (4-6) and R in formula (1) 1 The methylene bond on the side, the oxygen atom on the right terminal and R in formula (1) 4 Side methylene bonding.

9. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 With polar groups, R 4 With polar groups and x R 3 The total number of polar groups is 6 to 12.

10. The fluorine-containing ether compound according to claim 1 or 2, wherein the (x+1) R in the formula (1) 2 Each is independently a perfluoropolyether chain represented by the following formula (5): -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(5) In formula (5), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20, wherein: w2, w3, w4, and w5 are not all 0 at the same time; w1 and w6 are average values ​​of the number of CF2, and each independently represents 1 to 3; the arrangement order of the repeating units (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) in formula (5) is not particularly limited.

11. The fluorine-containing ether compound according to claim 1 or 2, wherein the (x+1)th R in the formula (1) 2 Each independently represents any one of the perfluoropolyether chains selected from the group consisting of the following formulae (5-1) to (5-4): -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(5-1) In formula (5-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(5-2) In formula (5-2), j represents the average degree of polymerization and is 1 to 15; -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(5-3) In formula (5-3), k represents the average degree of polymerization and is 1 to 10; -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(5-4) In formula (5-4), 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 groups, and each independently represents 1 to 2.

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

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

14. A magnetic recording medium, comprising at least a magnetic layer, a protective layer and a lubricating layer arranged in sequence on a substrate, wherein: The lubricating layer comprises the fluorine-containing ether compound according to claim 1 or 2. 15 . The magnetic recording medium according to claim 14 , wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm.

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