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. R < 1 >-CH < 2 >-R < 2 > [-CH < 2 >-R < 3 >-CH < 2 >-R < 2 >] < x >-CH < 2 >-R < 4 >, r2 is a perfluoropolyether chain; and R3 is represented by formula (2). (R1 and R4 are end groups having 1-4 polar groups and 1-50 carbon atoms) # imgabs0 #

Description

Technical Field

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

[0002] This application claims priority based on Japanese Patent Application No. 2022-158414 filed in Japan on September 30, 2022, and the contents are incorporated herein by reference. Background Art

[0003] In order to increase the recording density in a magnetic recording and reproducing device, a magnetic recording medium suitable for high recording density is 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, the magnetic recording medium cannot obtain sufficient durability by only providing the protective layer on the recording layer. Therefore, a lubricant is usually applied on 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, a lubricant containing a compound which is a fluorine-based polymer having a polar group such as a hydroxyl group or an amino group at the end and having a repeating structure containing -CF2- has been proposed.

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

[0007] Patent Documents 3 and 4 disclose the following fluorinated ether compounds, which contain a methylene group (-CH2-) and a group in which one hydrogen atom of the methylene group is substituted by a hydroxyl group (-CH(OH)-), and have a skeleton in which two perfluoropolyether chains are bonded via a divalent connecting group containing two hydroxyl groups, and terminal groups as organic groups containing polar groups are bonded at both ends via methylene groups.

[0008] Patent document 5 discloses the following fluorine-containing ether compound, which has a methylene group (-CH2-) and a group in which one hydrogen atom of the methylene group is substituted by a hydroxyl group (-CH(OH)-), and has a skeleton in which two or three perfluoropolyether chains are bonded via a divalent connecting group containing two hydroxyl groups, and terminal groups as organic groups having polar groups are bonded at both ends via methylene groups.

[0009] Patent Documents 6 and 7 disclose fluorinated ether compounds having a skeleton in which two perfluoropolyether chains are bonded via a divalent linking group containing a benzene ring or an alicyclic structure, and terminal groups having organic groups containing polar groups bonded at both ends via methylene (-CH2-) groups.

[0010] Prior art literature

[0011] Patent Literature

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

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

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

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

[0016] Patent Document 5: U.S. Patent No. 10262685

[0017] Patent Document 6: International Publication No. 2021 / 065380

[0018] Patent Document 7: International Publication No. 2022 / 113854 Summary of the invention

[0019] Problems to be solved by the invention

[0020] In recent years, in order to increase the capacity of magnetic recording media, it has been required to further reduce the magnetic gap (the distance between a magnetic head and a magnetic layer of a magnetic recording medium). Therefore, it is required to further reduce the thickness of the lubricating layer in the magnetic recording medium.

[0021] However, generally speaking, if the thickness of the lubricating layer is reduced, the chemical resistance of the magnetic recording medium tends to decrease. In addition, if spin-off occurs when the thickness of the lubricating layer is reduced, the film thickness sufficient to satisfy the function of the lubricating layer cannot be maintained. Spin-off is a phenomenon in which the lubricant is scattered or evaporated due to the centrifugal force and heat generated by the rotation of the magnetic recording medium.

[0022] 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 has excellent chemical resistance and can form a lubricating layer with suppressed spin separation and is suitable as a material for a lubricant for a magnetic recording medium.

[0023] Another object of the present invention is to provide a lubricant for a magnetic recording medium, which contains the fluorine-containing ether compound of the present invention and can form a lubricating layer having excellent chemical resistance and a high spin-off suppressing effect.

[0024] Another object of the present invention is to provide a magnetic recording medium having a lubricating layer containing the fluorinated ether compound of the present invention and having excellent chemical resistance and a high spin-off suppressing effect.

[0025] Means used to solve problems

[0026] The present invention includes the following aspects.

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

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

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

[0030] In formula (1), 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 represented by the following formula (2); when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms; R 1 and R 4 They can be the same or different;

[0031]

[0032] In the formula (2), Y represents an acyclic divalent saturated hydrocarbon group having 2 to 8 carbon atoms which may have an ether oxygen atom between carbon atoms.

[0033] The fluorine-containing ether compound according to the first aspect of the present invention preferably has the features described in the following [2] to

[10] . It is also preferred that any two or more of the features described in the following [2] to

[10] are combined.

[0034] [2] The fluorine-containing ether compound according to [1], wherein the formula (2) is a linking group represented by the following formula (2-1) or (2-2).

[0035]

[0036] In formula (2-1), a represents an integer of 2 to 8; a R a and Rb Each independently represents a hydrogen atom or a methyl group; a (-CR a R b -) contains 2 to 8 carbon atoms; the oxygen atom at the left terminal of formula (2-1) 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;

[0037] In formula (2-2), b represents an integer of 2 to 4; b R c Each independently represents -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2- or -CH2CH(CH3); b R c The total number of carbon atoms contained in is 4 to 8; the oxygen atom at the left end of formula (2-2) 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.

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

[0039]

[0040] 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 A represents an alkyl group that may have a polar group, an organic group that may have a polar group and contains a carbon-carbon unsaturated bond, or a hydrogen atom.

[0041] [4] The fluorinated ether compound according to any one of [1] to [3], wherein R in the formula (1) 1 and R 4 Each independently represents a terminal group represented by the following formula (3-1) or (3-2).

[0042]

[0043] 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 1 to 5, the total value of p and r is 1 to 5, and B represents a polar group;

[0044] In the formula (3-2), s represents an integer of 0-2, and t represents an integer of 1-5.

[0045] [5] The fluorinated ether compound according to any one of [1] to [4], wherein R in the formula (1) 1 and R 4 same.

[0046] [6] The fluorinated ether compound according to any one of [1] to [5], wherein R in the formula (1) 1 The polar groups and R 4 The total number of polar groups possessed is 2 to 6.

[0047] [7] The fluorinated ether compound according to any one of [1] to [6], wherein R in the formula (1) 1 The polar groups and R 4 All polar groups are hydroxyl groups.

[0048] [8] The fluorinated ether compound according to any one of [1] to [7], wherein the (x+1)th R in the formula (1) 2 Each independently is a perfluoropolyether chain represented by the following formula (4).

[0049] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0050] In formula (4), w2, w3, w4, and w5 represent the average degree of polymerization, and each independently represents 0 to 20; however, w2, w3, w4, and w5 are not 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 (4) is not particularly limited.

[0051] [9] The fluorinated ether compound according to any one of [1] to [7], wherein the (x+1)th R in the formula (1) 2 Each independently represents any one selected from the group consisting of perfluoropolyether chains represented by the following formulae (4-1) to (4-4).

[0052] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1)

[0053] In formula (4-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20;

[0054] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2)

[0055] In formula (4-2), j represents the average degree of polymerization and is 1 to 15;

[0056] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3)

[0057] In formula (4-3), k represents the average degree of polymerization and is 1 to 10;

[0058] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4)

[0059] In formula (4-4), w8 and w9 represent average polymerization degrees, and each independently represents 1 to 20; w7 and w10 represent average values ​​of the number of CF2, and each independently represents 1 to 2.

[0060]

[10] The fluorinated ether compound according to any one of [1] to [9], which has a number average molecular weight in the range of 500 to 10,000.

[0061] A second aspect of the present invention provides the following lubricant for a magnetic recording medium.

[0062]

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

[10] .

[0063]

[12] A magnetic recording medium comprising at least a magnetic layer, a protective layer and a lubricating layer provided in sequence on a substrate,

[0064] The lubricating layer contains the fluorine-containing ether compound according to any one of [1] to

[10] .

[0065] The magnetic recording medium according to the third aspect of the present invention preferably has the features described in the following

[13] .

[0066]

[13] The magnetic recording medium according to

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

[0067] Effects of the Invention

[0068] The fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is suitable as a material for a lubricant for magnetic recording media.

[0069] 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 chemical resistance and a high spin-off suppressing effect.

[0070] 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 chemical resistance, good spin-off suppression effect, and excellent reliability and durability. In addition, since the magnetic recording medium of the present invention has a lubricating layer that has good chemical resistance and can suppress spin-off, the thickness of the lubricating layer can be thinned to further reduce the magnetic spacing. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 It is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention. DETAILED DESCRIPTION

[0072] The present inventors have conducted intensive studies to solve the above-mentioned problems as described below.

[0073] In the past, as the material of the lubricant for magnetic recording media (hereinafter, sometimes referred to as "lubricant") coated on the surface of the protective layer, a fluorine-containing ether compound having polar groups such as hydroxyl groups at the end and the center of the chain structure was preferably used. The polar groups in the fluorine-containing ether compound are bonded to the active points on the protective layer, thereby improving the adhesion of the lubricant layer to the protective layer.

[0074] However, when a thin lubricating layer is formed on a protective layer using a lubricant containing a conventional fluorinated ether compound, it is difficult to realize a lubricating layer having good chemical resistance and a high spin-off suppressing effect as described below.

[0075] For example, in a fluorinated ether compound in which a divalent connecting group having only one hydroxyl group is arranged between multiple perfluoropolyether chains, the hydroxyl group of the divalent connecting group is hindered from adsorbing to the protective layer due to the sterically bulky perfluoropolyether chains arranged on both sides, and sometimes cannot participate in the interaction with the active points on the protective layer.

[0076] In addition, fluorinated ether compounds in which a bivalent linking group having a rigid structure is arranged between multiple perfluoropolyether chains may not participate in the interaction with the active points on the protective layer even if the bivalent linking group has multiple hydroxyl groups. This is because the bivalent linking group having a rigid structure cannot move freely, so when the perfluoropolyether chains arranged on both sides of the bivalent linking group perform molecular motion, they may move together with the perfluoropolyether chains and separate from the protective layer.

[0077] In addition, the fluorinated ether compound having a divalent linking group having a plurality of hydroxyl groups and the hydroxyl groups being close to each other is arranged between a plurality of perfluoropolyether chains, and a highly flexible structure (-O-CH2-CH(OH)-CH2-O-CH2-CH(OH)-CH2-O-) in which two glycerol structures are directly bonded can also be used, and the hydroxyl groups contained in the divalent linking group are also easy to interact with each other in the molecule. Therefore, the hydroxyl groups contained in the divalent linking group are unlikely to participate in the interaction with the polar groups contained in other fluorinated ether compound molecules present in the lubricating layer.

[0078] Thus, if there is a polar group in the fluorinated ether compound contained in the lubricant that does not participate in the interaction with the active point on the protective layer <1> or the polar group contained in other fluorinated ether compound molecules present in the lubricating layer <2>, contaminants are likely to enter the vicinity of the polar group. In addition, the adhesion with the protective layer is insufficient, and the lubricant is likely to scatter or evaporate due to the centrifugal force and heat associated with the rotation of the magnetic recording medium. Therefore, in the case where the polar group in the fluorinated ether compound contained in the lubricant is difficult to participate in the interaction with the above <1> or <2>, the chemical resistance and spin-off suppression effect of the lubricating layer are insufficient.

[0079] Therefore, the present inventors have conducted intensive studies focusing on the interaction between the polar groups in the fluorinated ether compound molecules contained in the lubricating layer and the above <1> and <2>.

[0080] As a result, it was found that the following fluorinated ether compound can be used, in which the divalent connecting group for bonding multiple perfluoropolyether chains via a methylene group (-CH2-) is a structure represented by formula (2) comprising two glycerol structures and a non-cyclic saturated hydrocarbon group of appropriate length arranged between them, and has terminal groups containing polar groups at both ends of the molecule.

[0081] The divalent linking group represented by formula (2) in such a fluorinated ether compound is a highly flexible structure in which two glycerol structures have hydroxyl groups, and the distance between the two glycerol structures is appropriately maintained by the acyclic saturated hydrocarbon group contained in the divalent linking group. Moreover, the acyclic saturated hydrocarbon group has higher fluidity than, for example, a cyclic organic group, and has little effect on hindering the movement of the two glycerol structures. Therefore, it is presumed that the hydroxyl groups contained in the divalent linking group represented by formula (2) can move freely and independently, and the interaction within the same fluorinated ether compound molecule is suppressed, and it is easy to participate in the interaction with the above <1> and <2>. The interaction between the hydroxyl groups contained in the divalent linking group represented by formula (2) and the above <1> contributes to the improvement of the adhesion between the lubricating layer and the protective layer. In addition, the interaction between the hydroxyl groups contained in the divalent linking group represented by formula (2) and the above <2> is an intermolecular interaction with other fluorinated ether compounds, which contributes to the formation of a dense film that is not easily separated from the protective layer. Therefore, the lubricating layer containing the fluorinated ether compound is dense and difficult to separate, has high adhesion to the protective layer, and is difficult to spin off. In addition, it is difficult to take in pollutants caused by hydroxyl groups that do not participate in the interaction with <1> and <2>, and has good chemical resistance.

[0082] Furthermore, in the above-mentioned fluorinated ether compound, the perfluoropolyether chain is disposed between the end group having a polar group and the divalent connecting group represented by formula (2). Therefore, due to the perfluoropolyether chain, the polar group in the end group and the hydroxyl group in the divalent connecting group are not easy to interact with each other in the molecule, and the end group and the connecting group can interact with the protective layer independently. That is, two or three perfluoropolyether chains have end groups or connecting groups that interact with the protective layer at both ends. Therefore, it is possible to suppress the perfluoropolyether chain from floating and becoming larger in volume. Thus, the lubricating layer containing the above-mentioned fluorinated ether compound can make the thickness further thinner. In other words, even if the thickness of the lubricating layer containing the above-mentioned fluorinated ether compound is reduced, the function as a lubricating layer can be maintained.

[0083] Furthermore, the present inventors have confirmed that a lubricating layer having excellent chemical resistance and a high spin-off suppressing effect can be formed by using a lubricant containing the above-mentioned fluorinated ether compound, and thus have conceived the present invention.

[0084] Below, the preferred examples of the fluorine-containing ether compound of the present invention, the lubricant for magnetic recording medium and the magnetic recording medium are described in detail. It should be noted that the present invention is not limited to the following embodiments. The present invention can add, omit, replace, and modify quantity, amount, position, ratio, material, composition, type, sequence, etc. within the scope of the gist of the present invention.

[0085] [Fluorinated ether compounds]

[0086] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

[0087] R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1)

[0088] 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 represented by the following formula (2); when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms; R 1 and R 4 They can be the same or different.

[0089]

[0090] In the formula (2), Y represents an acyclic divalent saturated hydrocarbon group having 2 to 8 carbon atoms which may have an ether oxygen atom between carbon atoms.

[0091] The fluorine-containing ether compound of this embodiment has R as shown in formula (1). 3 The divalent linking group represented by 2 The perfluoropolyether chains (hereinafter sometimes referred to as "PFPE chains") represented by the above are connected via methylene groups to form a skeleton. At one end of the skeleton, R 1 The other end of the skeleton is bonded with R 4 Indicates the end group.

[0092] In the fluorine-containing ether compound represented by formula (1), x represents an integer of 1 to 2. Since x in the fluorine-containing ether compound represented by formula (1) is an integer of 1 to 2, R 2 The number of PFPE chains (x+1) represented is 2 or 3, which is consistent with R 2 The number of PFPE chains represented is different from that of the compound with one adjacent R 2 R is configured between 3 Therefore, with R 2 Compared with the compound in which the number of PFPE chains represented by 1 is 1, a lubricating layer with excellent adhesion to the protective layer and less prone to spin-off can be obtained. 2Compared with compounds with 4 or more PFPE chains, the molecules do not become too large and can move freely. Therefore, it is easy to wet and spread on the protective layer, and it is easy to obtain a thin and uniform lubricating layer. In addition, since x is an integer of 1 to 2, the configuration of R 2 R 3 The number of is 1 or 2. Therefore, -R in formula (1) 2 [-CH2-R 3 -CH2-R 2 ] x - The number of hydroxyl groups it possesses is easy to become appropriate, and it is easy to obtain a lubricating layer with good adhesion to the protective layer. In addition, the fluorinated ether compound represented by formula (1) is less likely to produce polar groups that do not participate in the interaction with the active points on the protective layer or the polar groups contained in other fluorinated ether compounds present in the lubricating layer, and is less likely to produce the ingestion of pollutants caused by the hydroxyl groups that do not participate in the interaction with the above <1> and <2>, compared with the case where x is 3 or more, so that a lubricating layer with good chemical resistance can be formed.

[0093] (R 3 (represented by a divalent connecting group)

[0094] In the fluorine-containing ether compound represented by formula (1), x R 3 The divalent linking group represented by formula (2) has oxygen atoms at both ends of the chain structure and is bonded to R 3 The oxygen atom contained in the chain structure of the divalent connecting group represented by formula (2) forms an ether bond to impart moderate flexibility to the fluorine-containing ether compound represented by formula (1), thereby increasing the affinity of the hydroxyl group of the divalent connecting group represented by formula (2) with the protective layer.

[0095] The divalent connecting group represented by formula (2) has a glycerol structure (-O-CH2-CH(OH)-CH2-O-) at both ends. Since the glycerol structure is soft, the structure represented by formula (2) in which the two glycerol structures are connected by the non-cyclic saturated hydrocarbon group described later is extremely flexible. Therefore, when the perfluoropolyether chains arranged on both sides perform molecular motion, the two hydroxyl groups in the divalent connecting group represented by formula (2) can also move freely and independently, and it is easy to maintain the interaction between the hydroxyl groups in the divalent connecting group and the active points on the protective layer and the polar groups contained in other fluorinated ether compounds present in the lubricating layer. As a result, the number of hydroxyl groups in the divalent connecting group that may introduce pollutants and do not participate in the interaction becomes less. Therefore, the lubricating layer containing the above-mentioned fluorinated ether compound has excellent chemical resistance. In addition, since the hydroxyl groups in the two glycerol structures are easily involved in the interaction with the protective layer or the intermolecular interaction with other fluorinated ether compounds, the lubricating layer containing the above-mentioned fluorinated ether compound becomes dense, which inhibits the occurrence of spin separation.

[0096] The divalent linking group represented by formula (2) has two hydroxyl groups. Since the divalent linking group represented by formula (2) has two hydroxyl groups, the lubricating layer containing the fluorinated ether compound has good adhesion (closeness) to the protective layer. That is, even if the adsorption of one hydroxyl group in formula (2) to the protective layer is hindered due to the large volume of the perfluoropolyether chains adjacent to both sides, the other hydroxyl group can also adsorb the protective layer. Moreover, since the number of hydroxyl groups possessed by the above-mentioned divalent linking group is 2, in a magnetic recording medium having a lubricating layer containing a fluorinated ether compound, it is possible to prevent the molecules from aggregating with each other due to the high polarity of the fluorinated ether compound, thereby reducing the closeness to the protective layer and causing spin-off.

[0097] Y in the divalent linking group represented by formula (2) is a non-cyclic divalent saturated hydrocarbon group having 2 to 8 carbon atoms. Since the number of carbon atoms contained in Y is 2 or more, the distance between the hydroxyl groups in the two glycerol structures bonded to both sides of Y can be appropriately maintained. Therefore, the two hydroxyl groups in the divalent linking group represented by formula (2) can move independently of each other. In addition, since the number of carbon atoms contained in Y is 8 or less, the volume of Y becomes larger, thereby reducing the effect of hindering the movement of the two glycerol structures bonded to both sides of Y. The number of carbon atoms contained in Y is preferably 3 to 6. When the number of carbon atoms contained in Y is 3 or more, the distance between the two hydroxyl groups contained in the divalent linking group represented by formula (2) becomes more appropriate. As a result, the hydroxyl groups in the divalent linking group are easily involved in the interaction with the active points on the protective layer and the polar groups contained in other fluorinated ether compounds present in the lubricating layer. In addition, if the number of carbon atoms contained in Y is 3 or more, the affinity of the saturated hydrocarbon group to the pollutant is reduced, and the introduction of pollutants into the lubricating layer can be suppressed, so that the chemical resistance becomes better.

[0098] Y in the divalent linking group represented by formula (2) is a saturated hydrocarbon group. Therefore, compared with, for example, a case where Y has an unsaturated bond, the flexibility is high and the movement of the two glycerol structures bonded to both sides of Y is not easily hindered. In addition, Y in the divalent linking group represented by formula (2) is acyclic. Therefore, compared with, for example, a case where Y has a cyclic structure, the fluidity is high and the movement of the two glycerol structures bonded to both sides of Y is not easily hindered.

[0099] Y in the divalent linking group represented by formula (2) may contain an ether oxygen atom (—O—) between carbon atoms. When Y contains an ether oxygen atom between carbon atoms, the flexibility is further improved. Y may be a straight chain or a branched chain.

[0100] xR 3 Preferably, each independently is a divalent linking group represented by the following formula (2-1) or (2-2).

[0101]

[0102] In formula (2-1), a represents an integer of 2 to 8; R a and R b Each independently represents a hydrogen atom or a methyl group; a (-CR a R b -) contains 2 to 8 carbon atoms; the oxygen atom at the left terminal of formula (2-1) 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.

[0103] In formula (2-2), b represents an integer of 2 to 4; b R c Each independently represents -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2- or -CH2CH(CH3); b R c The total number of carbon atoms contained in is 4 to 8; the oxygen atom at the left terminal of formula (2-2) 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.

[0104] The divalent linking group represented by formula (2-1) is -OYO- in the divalent linking group represented by formula (2) is -O-(-CR a R b -) a -O- linking group. a represents an integer of 2 to 8. a R a and R bEach independently represents a hydrogen atom or a methyl group. In the divalent linking group represented by formula (2-1), two glycerol structures are linked via a saturated hydrocarbon group having no ether oxygen atom and having a total of 2 to 8 carbon atoms.

[0105] a(-CR a R b -) does not contain ether oxygen atoms, a R a and R b Each of them is independently a hydrogen atom or a methyl group, so the divalent linking group represented by formula (2-1) has low affinity for pollutants. a R b When the number of carbon atoms contained in -) is 3 or more, it becomes a fluorine-containing ether compound that can form a lubricating layer whose affinity with contaminants is further reduced and which is less likely to take in contaminants.

[0106] Since a in formula (2-1) is 2 or more, there are at least 8 atoms, not including ether oxygen atoms, between the hydroxyl groups contained in the glycerol structures at both ends. Therefore, the distance between the hydroxyl groups contained in the glycerol structures at both ends becomes appropriate. As a result, the hydroxyl groups contained in the glycerol structures at both ends can be suppressed from aggregating within the molecule, and can move independently. In addition, a in formula (2-1) is 8 or less, and a (-CR a R b -) is 8 or less, so the rigidity of the saturated hydrocarbon groups has little effect on hindering the movement of the glycerol structures at both ends.

[0107] Since the divalent linking group represented by formula (2-1) does not contain a saturated hydrocarbon group with an ether oxygen atom, the polarity around the glycerol structure at both ends is reduced, and the affinity with pollutants is reduced. 3 A fluorine-containing ether compound having a divalent linking group represented by the formula (2-1) is preferred because the lubricating layer has better chemical resistance.

[0108] As the divalent linking group represented by formula (2-2), -OYO- in the divalent linking group represented by formula (2) is -O-(R c -O) b -. b represents an integer from 2 to 4. b R c Each independently represents -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2- or -CH2CH(CH3)-. In the divalent linking group represented by formula (2-2), two glycerol structures are linked via a saturated hydrocarbon group containing an ether oxygen atom and having a total of 4 to 8 carbon atoms.

[0109] Since b in formula (2-2) is 2 or more, there are at least 11 atoms including ether oxygen atoms between the hydroxyl groups contained in the glycerol structures at both ends. Therefore, the distance between the hydroxyl groups contained in the glycerol structures at both ends becomes appropriate. As a result, the hydroxyl groups contained in the glycerol structures at both ends can be suppressed from aggregating within the molecule, and can move independently. In addition, b in formula (2-2) is 4 or less, there is an ether oxygen atom between the two glycerol structures, and b R c Since the total number of carbon atoms contained is 8 or less, the rigidity of the saturated hydrocarbon group has little effect of hindering the movement of the glycerol structures at both ends.

[0110] In the divalent linking group represented by formula (2-2), the saturated hydrocarbon group disposed between the two glycerol structures is a saturated hydrocarbon group having an ether oxygen atom and R c The regular arrangement of the repeating structure constitutes the fluorinated ether compound, thereby enhancing the intermolecular interaction of the fluorinated ether compound. 3 The lubricating layer of the fluorine-containing ether compound having a divalent linking group represented by the formula (2-2) becomes denser and spin-off is further suppressed, which is preferred.

[0111] When x is 2 in formula (1), the two R 3 They can be the same or different. 3 If the two R 3 The same refers to the R arranged at the center of the molecular chain structure. 2 , two R 3 The symmetric configuration of the atoms contained in it.

[0112] (R 1 and R 4 The end group represented by

[0113] In the fluorine-containing ether compound represented by formula (1), R 1 and R 4 It is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms.

[0114] In this embodiment, R 1 and R 4 Since they are the above-mentioned terminal groups, the lubricating layer containing the fluorine-containing ether compound represented by the formula (1) has excellent chemical resistance and a high effect of suppressing spin-off.

[0115] More specifically, R 1 and R 4The number of polar groups contained is one or more, so when a lubricating layer is formed on the protective layer using a lubricant containing a fluorinated ether compound, a suitable interaction occurs between the lubricating layer and the protective layer. As a result, a lubricating layer with excellent adhesion to the protective layer and a good spin-off inhibition effect is formed. In addition, R 1 and R 4 The number of polar groups contained is 4 or less, so R 1 and R 4 The polar groups contained in the fluorinated ether compound are unlikely to become groups that do not participate in the interaction with the active points on the protective layer or the polar groups contained in other fluorinated ether compounds present in the lubricating layer, and a lubricating layer having good chemical resistance and spin-off inhibition effect can be obtained. 1 and R 4 The number of polar groups contained is 4 or less, so that the polarity of the fluorinated ether compound is too high in the lubricating layer containing the fluorinated ether compound, the fluorinated ether compound aggregates, and the smoothness of the lubricating layer is prevented from being lost. 1 and R 4 The number of polar groups contained in the fluorine-containing ether compound is preferably 3 or less, and most preferably 2, in order to obtain a lubricating layer having better chemical resistance and spin-off suppression effect. 1 and R 4 When the number of polar groups contained is 2, the magnetic recording medium having a lubricating layer containing a fluorine-containing ether compound can be effectively suppressed. 1 and R 4 The polar groups of the terminal groups represented by are aggregated. 1 and R 4 The polar groups contained in the fluorinated ether compound are more likely to not participate in the interaction with the active points on the protective layer or the polar groups contained in other fluorinated ether compounds present in the lubricating layer. As a result, the fluorinated ether compound can prevent contaminants from entering the magnetic recording medium and can form a lubricating layer with better chemical resistance and spin-off suppression effect.

[0116] R 1 and R 4 can be the same or different. 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 number of polar groups possessed by both is preferably the same in order to make the coating state of the protective layer by the fluorinated ether compound more uniform and to form a lubricating layer having better adhesion.

[0117] R in formula (1)1 The polar groups and R 4 The total number of polar groups is preferably 2 to 6, more preferably 3 to 6, and even more preferably 4 to 6. When the total number of polar groups is 2 or more, R 1 and R 4 The interaction between the polar groups and the protective layer becomes more solid. Thus, it becomes a fluorine-containing ether compound that can form a lubricating layer with high adhesion to the protective layer. As a result, the lubricating layer formed by the fluorine-containing ether compound has excellent resistance to chemical substances. If the total number of the above-mentioned polar groups is less than 6, the polarity of the fluorine-containing ether compound will not become too high, and the affinity with pollutants can be kept lower. Therefore, it becomes a fluorine-containing ether compound that can form a lubricating layer with better resistance to chemical substances.

[0118] R 1 and R 4 The carbon number of each of the fluorinated ether compounds is 1 to 50, preferably 3 to 20, and more preferably 4 to 15. If the carbon number is 1 or more, the affinity with the pollutant is reduced, so that a lubricating layer with good chemical resistance is formed. If the carbon number is 50 or less, the terminal part becomes a soft structure, the adhesion of the fluorinated ether compound is improved, and a lubricating layer that can suppress spin-off is formed.

[0119] R 1 and R 4 R can be appropriately selected according to the performance required of the lubricant containing the fluorine-containing ether compound. 1 and R 4 The 1 to 4 polar groups respectively possessed may be partially or entirely the same or may be different from each other.

[0120] R 1 and R 4 The polar group is preferably selected from hydroxyl (-OH), amino (-NH2), carboxyl (-COOH), formyl (-(C=O)H), carbonyl (-CO-), sulfonyl (-SO)3H), cyano (-CN) and a group having an amide bond (-NR 7 COR 8 or-CONR 9 R 10 ; R 7 , R 8 , R 9 and R 10Each independently represents at least one of a hydrogen atom or an organic group. As the 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 7 and R 8 They may also be bonded to each other to form a ring. 9 and R 10 They may also be bonded to each other to form a ring. 7 , R 8 , R 9 and R 10 Preferably, they are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group.

[0121] Preferred R 1 and R 4 The polar groups are independently selected from at least one of 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 there is almost no effect of corroding the substrate.

[0122] R 1 and R 4 More preferably, each of them contains at least one hydroxyl group as a polar group. 1 and R 4 When a lubricant containing a fluorine-containing ether compound and containing a hydroxyl group is used to form a lubricant layer on the protective layer, a suitable interaction occurs between the lubricant layer and the protective layer, resulting in a lubricant layer having excellent adhesion to the protective layer and a good spin-off suppression effect.

[0123] R 1 and R 4 It is further preferred that all polar groups possessed are hydroxyl groups. 1 and R 4 All polar groups are hydroxyl groups, so that the coating state of the protective layer with the fluorine-containing ether compound can be made more uniform.

[0124] Among the fluorine-containing ether compounds represented by formula (1), R 1 and R 4 Each independently represents a terminal group represented by the following formula (3).

[0125]

[0126] 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 A represents an alkyl group that may have a polar group, an organic group that may have a polar group and contains a carbon-carbon unsaturated bond, or a hydrogen atom.

[0127] R 1 and R 4 When the terminal group is represented by formula (3), 2 The oxygen atom is bonded to the methylene group (-CH2-). 1 and R 4 , in R 1 and R 4 The ends of the groups each bonding to an adjacent CH2 have an oxygen atom. 1 and R 4 The oxygen atom disposed at the end of the fluorine-containing ether compound forms an ether bond (-O-) with the atoms bonded to both sides of the ether bond. The ether bond imparts moderate flexibility to the fluorine-containing ether compound represented by formula (1), thereby increasing R 1 and R 4 The polar group of the terminal group represented by formula (1) has affinity with the protective layer. Therefore, the fluorine-containing ether compound represented by formula (1) can form a lubricating layer having excellent adhesion with the protective layer.

[0128] 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, it is possible to prevent the affinity with pollutants from being increased due to excessive hydroxyl groups of the terminal groups represented by formula (3), and a lubricating layer with good chemical resistance can be obtained.

[0129] 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.

[0130] 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.

[0131] 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 is not reduced 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.

[0132] A in formula (3) represents an alkyl group which may have a polar group, an organic group which may have a polar group and contains a carbon-carbon unsaturated bond, or a hydrogen atom.

[0133] When A in the formula (3) is an alkyl group having no polar group, examples of A include methyl, ethyl, propyl, butyl, pentyl, and hexyl groups.

[0134] When A in formula (3) is an alkyl group having a polar group, as the polar group, R 1 and R 4 The groups listed as preferred examples of polar groups contained in the fluorine-containing ether compound are more preferably selected from at least one of a hydroxyl group, a cyano group and a group having an amide bond. Hydroxyl groups, cyano groups and groups 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, so they are preferred. In addition, the acidity of hydroxyl groups, cyano groups and groups having an amide bond is not too high, and there is almost no effect of corroding the substrate.

[0135] When A in formula (3) is an alkyl group having a polar group, examples of A include 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 2-aminoethyl, 3-aminopropyl, 2-carboxyethyl, 3-carboxypropyl, 2-carbonylethyl, 3-carbonylpropyl, 2-acetylethyl, 3-acetylpropyl, 2-sulfoethyl, 3-sulfopropyl, 2-cyanoethyl, 3-cyanopropyl, 4-cyanobutyl, 2-acetylaminoethyl, 3-acetylaminopropyl, 4-acetylaminobutyl, 2-formamidoethyl, 3-formamidopropyl, and 4-formamidobutyl.

[0136] Among the above groups, any one of 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl, 2-cyanoethyl, 3-cyanopropyl, 2-acetamidoethyl, 2-formamidoethyl and 3-formamidopropyl is preferred, and any one of 2-hydroxyethyl, 3-hydroxypropyl, 2-cyanoethyl, 3-cyanopropyl and 2-acetamidoethyl is more preferred.

[0137] When A in formula (3) is an organic group containing a carbon-carbon unsaturated bond, examples of A include organic groups containing at least one selected from aromatic hydrocarbons, unsaturated heterocyclic rings, alkenyl groups, and alkynyl groups. Among the functional groups (active sites) present in large quantities on the protective layer, there are sites where local charge is applied and sites where charge distribution is extended. 3The hydroxyl group contained in formula (3) exhibits adsorption ability by interacting with the local charged site on the protective layer through hydrogen atoms via hydrogen bonds. On the other hand, when the organic group represented by A contained in formula (3) is an organic group containing aromatic hydrocarbons, unsaturated heterocyclic rings, alkenyl groups, and alkynyl groups, they have non-localized charges and thus exhibit adsorption ability by interacting with the charge distribution extension site on the protective layer. Therefore, R represented by formula (2) 3 The hydroxyl group contained in formula (3) and the organic group containing a carbon-carbon unsaturated bond represented by A contained in formula (3) are mutually adsorbed at other positions on the protective layer. 3 The hydroxyl group contained in formula (3) and the organic group containing a carbon-carbon unsaturated bond represented by A contained in formula (3) can interact with the functional group (active point) on the protective layer independently. 1 and / or R 4 When it is a terminal group represented by formula (3) and A in formula (3) is an organic group containing a carbon-carbon unsaturated bond, the lubricating layer containing the fluorine-containing ether compound has excellent adhesion to the protective layer.

[0138] When A in formula (3) is an organic group having no polar group and containing a carbon-carbon unsaturated bond, examples of A include phenyl, methoxyphenyl, fluorophenyl, naphthyl, phenethyl, methoxyphenethyl, fluorophenethyl, benzyl, methoxybenzyl, naphthylmethyl, methoxynaphthyl, pyrrolyl, pyrazolyl, methylpyrazolylmethyl, imidazolyl, furanyl, furfuryl, oxazolyl, isoxazolyl, thienyl, thienylethyl, thiazolyl, methylthiazolylethyl, yl, 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.

[0139] Among the above groups, preferably any one of phenyl, methoxyphenyl, naphthyl, phenethyl, methoxyphenethyl, fluorinated phenethyl, thienylethyl, allyl, butenyl, and propargyl, more preferably any one of phenyl, methoxyphenyl, allyl, and butenyl. If A is any one of phenyl, methoxyphenyl, allyl, and butenyl, the interaction with the charge distribution extension site on the protective layer can be further enhanced, and the adhesion with the protective layer can be improved.

[0140] When A in formula (3) is an organic group having a polar group and containing a carbon-carbon unsaturated bond, the polar group may be 1 and R4 The groups listed as preferred examples of polar groups contained in the fluorine-containing ether compound are more preferably selected from at least one of a cyano group and a group having an amide bond. 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, so they are preferred. In addition, the acidity of the cyano group and the group having an amide bond is not too high, and there is almost no effect of corroding the substrate.

[0141] When A in formula (3) is an organic group having a polar group and containing a carbon-carbon unsaturated bond, examples of A include cyanophenyl, formamidophenyl, acetamidophenyl, cyanonaphthyl, formamidonaphthyl, acetamidonaphthyl, cyanophenethyl, formamidophenethyl, acetamidophenethyl, cyanobenzyl, formamidobenzyl, and acetamidobenzyl.

[0142] Among the above groups, any one of cyanophenyl, formamidophenyl, acetamidophenyl, cyanonaphthyl, formamidonaphthyl, acetamidonaphthyl, cyanobenzyl, formamidobenzyl and acetamidobenzyl is preferred, and any one of cyanophenyl, formamidophenyl and acetamidophenyl is more preferred.

[0143] When A in formula (3) is a hydrogen atom, A forms a hydroxyl group with the oxygen atom in formula (3). When A is a hydrogen atom, the repeating unit (-(CH2) m -CH(OH)-(CH2) n -O-), n is preferably 2 or more. In the repeating unit to which A is bonded, when n is 2 or more, the distance between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group becomes more appropriate, and the adhesion with the protective layer can be improved.

[0144] Among the fluorine-containing ether compounds represented by formula (1), R 1 and R 4 Each independently represents a terminal group represented by the formula (3-1) or (3-2).

[0145]

[0146] In the formula (3-1), p represents an integer of 0 to 3, q ​​represents an integer of 0 to 2, r represents an integer of 1 to 5, the total value of p and r is 1 to 5, and B represents a polar group.

[0147] In the formula (3-2), s represents an integer of 0-2, and t represents an integer of 1-5.

[0148] Each polar group contained in the terminal group represented by formula (3-1) and formula (3-2) is bonded to a different carbon atom. In formula (3-1) and formula (3-2), the carbon atoms bonded to the polar groups are bonded to each other via a connecting group containing a carbon atom to which the polar groups are not bonded. Therefore, R 1 and / or R 4 When the terminal group is represented by formula (3-1) or formula (3-2), the terminal polar group and the hydroxyl group adjacent to the terminal polar group can form an orientation that can be closely attached to the protective layer through a connecting group containing a carbon atom to which the polar group is not bonded. Therefore, it can be inferred that the lubricating layer containing a fluorine-containing ether compound represented by formula (1) can inhibit spin-off.

[0149] In the terminal group represented by formula (3-1), the connecting group between the carbon atom to which the polar group B disposed at the terminal is bonded and the carbon atom to which the hydroxyl group adjacent to the polar group B disposed at the terminal is bonded contains an oxygen atom forming an ether bond. In formula (3-1), p represents an integer of 0 to 3, r represents an integer of 1 to 5, and the total value of p and r is 1 to 5. Therefore, the above-mentioned connecting group has a linear structure composed of 3 to 7 atoms including the polar group B and the carbon atom to which the hydroxyl group is not bonded.

[0150] In the terminal group represented by formula (3-1), the above-mentioned connecting group is a linear structure composed of 3 or more atoms including an oxygen atom forming an ether bond and a carbon atom not bonded to the polar group B and the hydroxyl group, so the distance between the polar group B and the hydroxyl group adjacent to the polar group B is appropriate. Therefore, the interaction between the polar group B and the hydroxyl group adjacent to the polar group B in the molecule can be suppressed, and the polar group B and the hydroxyl group adjacent to the polar group B can both be closely attached to the protective layer. In addition, the above-mentioned connecting group is a linear structure composed of 3 or more 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 close adhesion to the protective layer.

[0151] In the end group represented by formula (3-1), since the above-mentioned connecting group is a linear structure composed of 7 or less atoms including an oxygen atom forming an ether bond and carbon atoms not bonded to the polar group B and the hydroxyl group, the connecting group becomes too large and the effect of hindering the movement of the polar group is small. Therefore, the lubricating layer of the fluorine-containing ether compound having an end group represented by formula (3-1) and a connecting group having a linear structure formed by 3 to 7 atoms including carbon atoms not bonded to the polar group B and the hydroxyl group has excellent adhesion to the protective layer, shows high chemical resistance, and has a good spin-off inhibition effect.

[0152] 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 occurrence of intramolecular interactions between nearby polar groups in preference to interactions between the polar groups and the protective layer, thereby improving the adhesion between the polar groups 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 coat 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, the flexibility of the terminal part is reduced by the rigid alkylene chain length, which can prevent the weakening of the interaction with the protective layer and the floating of the terminal part. p is preferably 0 or 1, and more preferably 0. r is preferably 1 or 2, and more preferably 1.

[0153] In formula (3-1), B represents a polar group. As B, preferably used is 1 and R 4 The groups are listed as preferred examples of polar groups contained in the fluorine-containing ether compound. Among these polar groups, B is more preferably a polar group selected from a hydroxyl group, a cyano group, and a group having an amide bond. This is because hydroxyl groups, cyano groups, and groups 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 groups, cyano groups, and groups having an amide bond is not too high, and there is almost no effect of corroding the substrate.

[0154] In formula (3-1), q represents an integer of 0 to 2. The number of polar groups in formula (3-1) is q+2. As described above, preferably R 1 and R 4 The number of polar groups contained is 3 or less, and most preferably 2. Therefore, q in formula (3-1) is preferably 0 or 1, and more preferably 0.

[0155] 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. Therefore, the intramolecular interaction is small, and intramolecular aggregation is not easy 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. The above-mentioned connecting group contained in formula (3-2) is a straight-chain structure composed of one or more atoms of carbon atoms containing unbonded hydroxyl groups, so the distance between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group is appropriate. Therefore, the interaction between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group in the molecule can be suppressed, and intramolecular aggregation is not easy to occur.

[0156] In addition, similarly to formula (3-1), 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, it is possible to prevent the flexibility of the terminal part from being reduced and the interaction between the terminal hydroxyl group and the protective layer from being reduced. t is preferably 1 or 2, more preferably 1.

[0157] Furthermore, since the linking group has a linear structure composed of 5 or less atoms excluding an oxygen atom forming an ether bond and including a carbon atom to which a hydroxyl group is not bonded, the effect of the linking group becoming too large and thereby inhibiting the movement of the hydroxyl group is small.

[0158] Therefore, the lubricating layer containing the fluorine-containing ether compound whose connecting group has a linear structure consisting of 1 to 5 atoms which do not contain oxygen atoms forming ether bonds and contain carbon atoms which are not bonded to hydroxyl groups has excellent adhesion to the protective layer, can obtain excellent chemical resistance, and has a good effect of inhibiting spin-off.

[0159] 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 is preferably 1 and R 4 The number of polar groups contained is 3 or less, and most preferably 2. Therefore, s in formula (3-2) is preferably 0 or 1, and more preferably 0.

[0160] When x in formula (1) is 2, there are two R 3 Since R represented by formula (2) 3 Each of the fluorinated ether compounds has two hydroxyl groups, and when x is 2, R 1 and R 4 The proportion of polar groups in the protective layer decreases. Since the number of active sites in the protective layer is limited, R 1 and R 4 When the ratio of the number of polar groups in the 1 and R 4 Therefore, when x is 2, R 1 and R 4 These are Formula (3-1) or Formula (3-2), which are structures that have a relatively strong interaction with the protective layer. 1 and R 4 When the formula (3-1) or formula (3-2) is respectively, for example, in R 1 and / or R 4In the case where the carbon atoms to which the hydroxyl groups are bonded are directly connected to each other, the hydroxyl groups in the molecule are less likely to aggregate with each other and are more likely to interact with the protective layer. 1 and R 4 In the case of Formula (3-1) or Formula (3-2), even if x is 2, the terminal portion in the fluorine-containing ether compound is unlikely to float up, and the adhesion with the protective layer is unlikely to decrease.

[0161] (R 2 PFPE chain represented by

[0162] In the fluorine-containing ether compound represented by formula (1), R 2 R is a perfluoropolyether 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 can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, etc.

[0163] (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 more uniform, forming a lubricating layer with better adhesion. (x+1) R 2 2 or more R 2 The same means that (x+1) R 2 The repeating units containing two or more PFPE chains have the same structure R 2 The same R 2 This also includes the case where the repeating units have the same structure but different average polymerization degrees.

[0164] 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.

[0165] Preferably, (x+1) R in formula (1) 2 Each is independently a PFPE chain represented by the following formula (4) derived from, for example, a polymer or copolymer of a perfluoroalkylene oxide.

[0166] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3-(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0167] In formula (4), w2, w3, w4, and w5 represent the average degree of polymerization, 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 the average value 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 (4) is not particularly limited.

[0168] In formula (4), 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.

[0169] In formula (4), w1 and w6 represent the average value of the number of CF2, and each independently represents 1 to 3. w1 and w6 can be determined based on the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (4).

[0170] In formula (4), (CF2O), (CF2CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) are repeating units. The arrangement order of the repeating units in formula (4) is not particularly limited. In addition, the number of types of repeating units in formula (4) is not particularly limited.

[0171] Preferably, (x+1) R in formula (1) 2 Each independently represents any one selected from the PFPE chains represented by the following formulae (4-1) to (4-4).

[0172] (x+1) R 2 When each of the (x+1) R is selected from any one of the PFPE chains represented by formulas (4-1) to (4-4), a fluorine-containing ether compound can be used to obtain a lubricating layer having good lubricity. 2 When each of the PFPE chains represented by formulas (4-1) to (4-4) is selected, the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) in the PFPE chain to the number of carbon atoms is appropriate. Therefore, a fluorine-containing ether compound having a moderate hardness is obtained. Therefore, the fluorine-containing ether compound applied on the protective layer is not easily aggregated on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage. 2The lubricating layer formed of a fluorinated ether compound selected from any one of the PFPE chains represented by formulae (4-1) to (4-4) becomes denser and can further suppress spin-off.

[0173] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1)

[0174] In the formula (4-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20.

[0175] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2)

[0176] In the formula (4-2), j represents an average degree of polymerization and is 1 to 15.

[0177] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3)

[0178] In the formula (4-3), k represents an average degree of polymerization and is 1 to 10.

[0179] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4)

[0180] In formula (4-4), w8 and w9 represent average polymerization degrees, and each independently represents 1 to 20; w7 and w10 represent average values ​​of the number of CF2, and each independently represents 1 to 2.

[0181] In formula (4-1), the arrangement order of (OCF2CF2) and (OCF2) as repeating units is not particularly limited. In formula (4-1), the number h of (OCF2CF2) and the number i of (OCF2) may be the same or different. The PFPE chain represented by formula (4-1) may also be a polymer of (OCF2CF2). In addition, the PFPE chain represented by formula (4-1) may also be any one of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF2CF2) and (OCF2).

[0182] In formulas (4-1) to (4-3), since h, which represents the average degree of polymerization, is 1 to 20, i is 0 to 20, j is 1 to 15, and k is 1 to 10, a fluorinated ether compound can be obtained that can provide a lubricating layer having good lubricity. In addition, in formulas (4-1) to (4-3), since h and i, which represent the average degree of polymerization, are 20 or less, j is 15 or less, and k is 10 or less, the viscosity of the fluorinated ether compound does not become too high, and a lubricant containing the fluorinated ether compound is easy to apply, which is preferred. In order to obtain a fluorinated ether compound that can easily wet and spread on the protective layer and easily obtain a lubricating layer having 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 even more preferably 2 to 7.

[0183] In formula (4-4), the arrangement order of (CF2CF2CF2O) and (CF2CF2O) as repeating units is not particularly limited. In formula (4-4), the number w8 of (CF2CF2CF2O) and the number w9 of (CF2CF2O) representing the average degree of polymerization may be the same or different. Formula (4-4) may include any one of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF2CF2CF2O) and (CF2CF2O).

[0184] In formula (4-4), w8 and w9 representing the average degree of polymerization are each independently 1-20, preferably 1-15, and more preferably 1-10.

[0185] w7 and w10 in formula (4-4) represent the average value of the number of CF2, and each independently represents 1 to 2. w7 and w10 can be determined based on the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (4-4).

[0186] In the fluorine-containing ether compound represented by formula (1), when x is 1, it is preferred that two R 2 Same, R 1 and R 4 This is to form a fluorine-containing ether compound that can be easily and efficiently produced.

[0187] In the fluorine-containing ether compound represented by formula (1), when x is 2, it is preferred that two R 3 Same, R 1 Side R 2 and R 4 Side R 2 Same, R 1 and R 4 This is to form a fluorine-containing ether compound that can be easily and efficiently produced.

[0188] 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 (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG).

[0189] When the compound represented by formula (1) is any one of the compounds represented by the following formulas (AA) to (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG), the raw materials are easy to obtain, and even if the thickness is thin, the chemical resistance is further improved, thereby forming a lubricating layer with good spin-off suppression effect on the magnetic recording medium.

[0190] In the compounds represented by the following formulas (AA) to (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG), Rf1, Rf2, and Rf3 representing the PFPE chain are the following structures. That is, in the compounds represented by the following formulas (AA) to (AJ), (BC) to (BR), (CA) to (CF), and (DB) to (DG), Rf1 is the PFPE chain represented by the above formula (4-1). In the compounds represented by the following formulas (BA) and (DA), Rf2 is the PFPE chain represented by the above formula (4-2). In the compound represented by the following formula (BB), Rf3 is the PFPE chain represented by the above formula (4-3). It should be noted that h and i in Rf1, j in Rf2, and k in Rf3 of the PFPE chains in the expression formulas (AA) to (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG) represent the average degree of polymerization and are not necessarily integers.

[0191]

[0192] In the compounds represented by the following formulae (AA) to (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG), R 3 It is a linking group represented by the above formula (2-1) or (2-2).

[0193] In the compounds represented by the following formulae (AA) to (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG), R 1 and R 4 Each of them is a terminal group represented by the above formula (3), formula (3-1) or formula (3-2).

[0194] In the compounds represented by the following formulae (AA) to (AG), x in the formula (1) is 1. 3 is a linking group represented by the above formula (2-1). 1 and R 4 is the terminal group represented by the above formula (3-1).2 It is the PFPE chain represented by the above formula (4-1).

[0195] In the compounds represented by the following formulae (AH) to (AJ), x in the formula (1) is 1. 3 is a connecting group represented by the above formula (2-2). 1 and R 4 is the terminal group represented by the above formula (3-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0196] In the compounds represented by the following formulae (BA) and (BB), x in the formula (1) is 1. 3 is a linking group represented by the above formula (2-1). 1 and R 4 is the terminal group represented by the above formula (3-1). 2 is the PFPE chain represented by the above formula (4-2), and for formula (BB), R 2 It is the PFPE chain represented by the above formula (4-3).

[0197] In the compounds represented by the following formulae (BC) to (BR), x in formula (1) is 1. 3 is a linking group represented by the above formula (2-1). For formulas (BC), (BE), (BF), (BH) to (BJ), (BL), (BQ), and (BR), R 1 and R 4 is the terminal group represented by the above formula (3-1), and for the formulas (BD), (BG), and (BK), R 1 and R 4 is the terminal group represented by the above formula (3-2), and for formulas (BM) to (BP), R 1 and R 4 It is an end group represented by the formula (3) which does not belong to the above-mentioned formula (3-1) and formula (3-2). 2 It is the PFPE chain represented by the above formula (4-1).

[0198] The compounds represented by the following formulae (CA) to (CE), wherein x in formula (1) is 2. 3 is a linking group represented by the above formula (2-1). 1 and R 4 is the terminal group represented by the above formula (3-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0199] A compound represented by the following formula (CF), wherein x in the formula (1) is 2. 3 is a connecting group represented by the above formula (2-2).1 and R 4 is the terminal group represented by the above formula (3-1). 2 It is the PFPE chain represented by the above formula (4-1).

[0200] A compound represented by the following formula (DA), wherein x in the formula (1) is 2. 3 is a linking group represented by the above formula (2-1). 1 and R 4 is the terminal group represented by the above formula (3-1). 2 It is the PFPE chain represented by the above formula (4-2).

[0201] The compounds represented by the following formulae (DB) to (DG), wherein x in formula (1) is 2. 3 is a linking group represented by the above formula (2-1). 1 and R 4 is an end group represented by formula (3) which does not belong to the above formula (3-1), and R in formula (DC) 1 and R 4 is an end group represented by formula (3) which does not belong to the above formula (3-2), and R in formula (DG) 1 and R 4 It is an end group represented by the formula (3) which does not belong to the above formula (3-1) and formula (3-2). 2 It is the PFPE chain represented by the above formula (4-1).

[0202]

[0203] 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; h and i in the two Rf1 may be the same or different.

[0204] 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; h and i in the two Rf1 may be the same or different.

[0205] 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; h and i in the two Rf1 may be the same or different.

[0206] 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; h and i in the two Rf1 may be the same or different.

[0207]

[0208] 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; h and i in the two Rf1 may be the same or different.

[0209] 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; h and i in the two Rf1 may be the same or different.

[0210] 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; h and i in the two Rf1 may be the same or different.

[0211] 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; h and i in the two Rf1 may be the same or different.

[0212]

[0213] 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; h and i in the two Rf1 may be the same or different.

[0214] 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; h and i in the two Rf1 may be the same or different.

[0215]

[0216] In the two Rf2 in the formula (BA), j represents the average degree of polymerization, which is 1 to 15; j in the two Rf2 may be the same or different.

[0217] In the two Rf3 in the formula (BB), k represents the average degree of polymerization, which is 1 to 10; k in the two Rf3 may be the same or different.

[0218] 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; h and i in the two Rf1 may be the same or different.

[0219] 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; h and i in the two Rf1 may be the same or different.

[0220]

[0221] 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; h and i in the two Rf1 may be the same or different.

[0222] 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; h and i in the two Rf1 may be the same or different.

[0223] 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; h and i in the two Rf1 may be the same or different.

[0224] 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; h and i in the two Rf1 may be the same or different.

[0225]

[0226] 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; h and i in the two Rf1 may be the same or different.

[0227] 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; h and i in the two Rf1 may be the same or different.

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

[0229] In the two Rf1 in the formula (BL), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the two Rf1 may be the same or different.

[0230]

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

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

[0233] In the two Rf1 in the formula (BO), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the two Rf1 may be the same or different.

[0234] In the two Rf1 in the formula (BP), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the two Rf1 may be the same or different; Me represents a methyl group.

[0235]

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

[0237] In the two Rf1 in the formula (BR), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the two Rf1 may be the same or different.

[0238]

[0239] 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; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0240] 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; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0241] 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; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0242]

[0243] 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; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0244] 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; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0245] 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; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0246]

[0247] In the formula (DA), j in the three Rf2 represents an average degree of polymerization, which is 1 to 15; j in the three Rf2 may be partially or entirely the same, or may be different from each other.

[0248] In the three Rf1 in the formula (DB), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0249] In the three Rf1 in the formula (DC), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be partially or completely the same, or may be different.

[0250]

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

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

[0253] In the three Rf1 in the formula (DF), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; h and i in the three Rf1 may be partially or completely the same, or may be different.

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

[0255] The number average molecular weight (Mn) of the fluorinated ether compound of the present embodiment is preferably in the range of 500 to 10,000, and particularly preferably in the range of 1,000 to 5,000. 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 lubricating layer with a thin film thickness 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.

[0256] The number average molecular weight (Mn) of the fluorinated ether compound was determined using AVANCE III 400 manufactured by Bruker BioSpin. 1 H-NMR determination and 19 The value obtained by F-NMR measurement. 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 for F-NMR chemical shifts was the peak of hexafluorobenzene assigned to -164.7 ppm. 1 The standard for H-NMR chemical shifts was the peak of acetone assigned to 2.2 ppm.

[0257] 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.

[0258] 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.

[0259] "Method of preparation"

[0260] 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, for example, by the following method.

[0261] [First preparation method (when x is 1)]

[0262] (R 1 and R 4 Same, two R 2 Same as

[0263] Preparation of R in formula (1) 2 The corresponding perfluoropolyether chain has fluoro compounds with hydroxymethyl (-CH2OH) at both ends.

[0264] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the fluorine-based compound is fused with a hydroxyl group having the same structure as R in formula (1). 1 The corresponding group (= with R 4 Thus, R 2 One end of the corresponding perfluoropolyether chain has a 1 The corresponding group (= with R 4 The intermediate compound 1-1 of the corresponding group).

[0265] As R in formula (1) 1 The corresponding group (= with R 4 The epoxy compound of the corresponding group) can be, for example, the compounds represented by the following formulas (5-1) to (5-16). THP in the following formulas (5-1) to (5-13) represents a tetrahydropyranyl group. Me in the following formula (5-14) represents a methyl group.

[0266]

[0267] It has the same R as in formula (1) 1 The corresponding group (= with R 4 The epoxy compound having a corresponding group) can be prepared by the method shown below. That is, it can be prepared by the following method: prepare a 1 or R 4 A diol having a structure corresponding to the partial end group represented by the formula is prepared, and after protecting one hydroxyl group by a known method, it is reacted with a halogen compound such as a bromine compound or a chlorine compound having an epoxy group. For example, in the case of preparing a compound represented by formula (5-2), as shown in the following formula (6-1), the following method can be used to prepare the compound: one hydroxyl group of the diol having the corresponding structure is protected using dihydropyran (DHP), and then reacted with epibromohydrin. THP in the following formula (6-1) represents tetrahydropyranyl.

[0268]

[0269] The above-mentioned epoxy compound can be prepared by the method shown below. That is, 2-(2-bromoethoxy)tetrahydro-2H-pyran and a compound having the same R as in formula (1) can be reacted. 1 or R 4The hydroxyl group of the alkenyl alcohol corresponding to the part of the terminal groups represented by the formula is reacted. Then, the obtained compound is oxidized by the action of m-chloroperbenzoic acid (mCPBA) to prepare it. For example, the compound represented by formula (5-4) can be prepared by a method in which 2-(2-bromoethoxy)tetrahydro-2H-pyran is reacted with 3-butene-1-ol and then oxidized by the action of m-chloroperbenzoic acid as shown in the following formula (6-2). THP in the following formula (6-2) represents tetrahydropyranyl.

[0270]

[0271] The above-mentioned epoxy compound can be prepared by the method shown below. That is, the epoxy compound having the same R as in formula (1) can be prepared by a known method. 1 or R 4 The epoxy compound has a structure corresponding to the partial terminal group represented by and has a hydroxyl group protected by a protecting group at one end. 1 or R 4 The alcohol of the alkenyl group corresponding to the part of the terminal groups represented by the formula is subjected to an addition reaction. Then, the obtained compound is oxidized by the action of meta-chloroperbenzoic acid (mCPBA) to prepare it. Before the compound obtained by the addition reaction is oxidized by the action of meta-chloroperbenzoic acid (mCPBA), the hydroxyl group generated by the addition reaction can be protected by a known method. For example, the compound represented by formula (5-5) can be prepared by a method in which the epoxy compound represented by formula (5-1) is subjected to an addition reaction with allyl alcohol as shown in the following formula (6-3), and then protected with dihydropyran (DHP), and oxidized by the action of meta-chloroperbenzoic acid (mCPBA). THP in the following formula (6-3) represents tetrahydropyranyl.

[0272]

[0273] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the intermediate compound 1-1 generated in the first reaction is reacted with R in the formula (1). 3 The corresponding compound having two epoxy groups is reacted (second reaction).

[0274] As R in formula (1) 3 As the corresponding compound having two epoxy groups, for example, compounds represented by the following formula (7-1) to (7-10) can be used.

[0275]

[0276] With R in formula (1) 3The corresponding compound having two epoxy groups can be prepared by the method shown below. 3 The compound represented by formula (7-1) can be prepared by reacting a diol having a structure corresponding to Y in formula (2) of a divalent linking group represented by the formula (7-1) with a 2-fold molar amount of epibromohydrin. For example, the compound represented by formula (7-1) can be prepared by reacting 1,3-propanediol with a 2-fold molar amount of epibromohydrin as shown in the following formula (8-1).

[0277]

[0278] With R in formula (1) 3 The corresponding compound having two epoxy groups can be prepared by a method of allowing a compound having two alkenyl groups to react with m-chloroperbenzoic acid (mCPBA) for oxidation, or a commercially available product can be used.

[0279] After the above steps, a deprotection reaction is carried out using a known method, thereby preparing a compound in which x is 1 and R 1 and R 4 Same, two R 2 Same compound.

[0280] [Second preparation method (when x is 1)]

[0281] (R 1 and R 4 Different and / or two R 2 Not at the same time)

[0282] First, make the 1 Side R 2 The corresponding perfluoropolyether chain has two hydroxyl groups at one end of the fluoro compound and a hydroxymethyl group at both ends. 1 The corresponding group of epoxy compounds is reacted to give the intermediate compound 1a (first reaction).

[0283] Next, make the 4 Side R 2 The corresponding perfluoropolyether chain has two hydroxyl groups at one end of the fluoro compound and a hydroxymethyl group at both ends. 4 The corresponding group of epoxy compounds is reacted to obtain the intermediate compound 1b (second reaction).

[0284] Next, the hydroxyl group at one end of the intermediate compound 1a is reacted with R in the formula (1) 3 After the corresponding compounds having an epoxy group and an alkenyl group are reacted, the double bond of the generated compound is oxidized to obtain an intermediate compound 1-2 (third reaction).

[0285] As R in formula (1)3 As the corresponding compound having an epoxy group and an alkenyl group, for example, compounds represented by formulae (9-1) to (9-10) described later can be used.

[0286] Next, the hydroxyl group at one terminal of the intermediate compound 1b is reacted with the epoxy group of the intermediate compound 1-2 obtained in the third reaction (fourth reaction).

[0287] After the above steps, a deprotection reaction is carried out using a known method, thereby preparing a compound in which x is 1 and R 1 and R 4 Different and / or two R 2 Different compounds.

[0288] [Third preparation method (when x is 2)]

[0289] (R 1 and R 4 Same, two R 3 Same, R 1 Side R 2 and R 4 Side R 2 Same as

[0290] First, the same operation as in the first preparation method is performed to obtain 1 Side and R 4 Side R 2 At one end of the corresponding perfluoropolyether chain, there is 1 The corresponding group (= with R 4 The intermediate compound 1-1 (the first reaction) is obtained by the reaction of

[0291] Next, prepare the R 2 The corresponding perfluoropolyether chains are provided with hydroxymethyl (-CH2OH) fluorine compounds at both ends. Then, the hydroxyl groups of the hydroxymethyl groups provided at both ends of the fluorine compounds are combined with R in formula (1) 3 The corresponding compounds having epoxy and alkenyl groups are reacted to obtain the intermediate compound 2-1 (second reaction).

[0292] As R in formula (1) 3 As the corresponding compound having an epoxy group and an alkenyl group, for example, compounds represented by the following formula (9-1) to (9-10) can be used.

[0293]

[0294] With R in formula (1) 3The corresponding compounds having epoxy and alkenyl groups can be prepared by the following method. 3 The compound represented by formula (9-1) can be prepared by a method of sequentially reacting a diol having a structure corresponding to Y in formula (2) of a divalent linking group represented by 1,3-propylene glycol, allyl bromide and epibromohydrin. For example, the compound represented by formula (9-1) can be prepared by a method of sequentially reacting 1,3-propylene glycol, allyl bromide and epibromohydrin as shown in the following formula (10-1).

[0295]

[0296] With R in formula (1) 3 The corresponding compound having an epoxy group and an alkenyl group can be prepared by a method in which m-chloroperbenzoic acid (mCPBA) is allowed to act on a compound having two alkenyl groups to oxidize one of the alkenyl groups, or a commercially available product can be used.

[0297] Next, m-chloroperbenzoic acid (mCPBA) is allowed to act on the intermediate compound 2-1 generated in the second reaction to oxidize it (third reaction). 2 The two ends of the corresponding perfluoropolyether chain have the same 3 The corresponding intermediate compound 3-1 has an epoxy group. The third reaction can be carried out after appropriately protecting the hydroxyl group of the intermediate compound 2-1 by a known method.

[0298] Then, the hydroxyl group of the methylol group disposed at one end of the intermediate compound 1-1 is reacted with the epoxy groups disposed at both ends of the intermediate compound 3-1 (fourth reaction).

[0299] After the above steps, a deprotection reaction is performed to produce a compound in which x is 2 and R 1 and R 4 Same, two R 3 Same, R 1 Side R 2 and R 4 Side R 2 Same compound.

[0300] [The fourth preparation method (when x is 2)]

[0301] (R 1 Side R 3 and R 4 Side R 3 Same, R 1 and R 4 Different and / or R 1 Side R 2 and R 4Side R 2 Not at the same time)

[0302] In the first reaction of the third production method, the intermediate compound 1a and the intermediate compound 1b in the second production method are obtained instead of the intermediate compound 1-1. Then, the same operation as the second reaction and the third reaction of the third production method is carried out to obtain the intermediate compound 3-1. Then, the intermediate compound 1a and the intermediate compound 1b are reacted in sequence with respect to the epoxy groups disposed at both ends of the intermediate compound 3-1.

[0303] After the above steps, a deprotection reaction is performed to produce a compound in which x is 2 and R 1 Side R 3 and R 4 Side R 3 Same, R 1 and R 4 Different and / or R 1 Side R 2 and R 4 Side R 2 Different compounds.

[0304] [Fifth Preparation Method (when x is 2)]

[0305] (R 1 Side R 3 and R 4 Side R 3 Different, R 1 and R 4 Same, R 1 Side R 2 and R 4 Side R 2 Same as

[0306] In the second reaction of the third preparation method, R 3 The corresponding compound having epoxy group and alkenyl group is made to react with R in formula (1) 1 Side R 3 The corresponding compound having epoxy group and alkenyl group, and R in formula (1) 4 Side R 3 The corresponding compounds having epoxy and alkenyl groups react with the above fluorine compounds in sequence to obtain intermediate compound 2-2. Then, the same operation as the third preparation method is carried out except that intermediate compound 2-2 is used instead of intermediate compound 2-1 to carry out the third reaction and the fourth reaction.

[0307] After the above steps, a deprotection reaction is performed to produce a compound in which x is 2 and R 1 Side R 3and R 4 Side R 3 Different, R 1 and R 4 Same, R 1 Side R 2 and R 4 Side R 2 Same compound.

[0308] In the third to fifth production methods for preparing a compound wherein x is 2, R 2 The corresponding perfluoropolyether chains can be combined with other R 2 The same, or different.

[0309] [Lubricant for magnetic recording media]

[0310] The lubricant for magnetic recording media according to the present embodiment contains the fluorine-containing ether compound represented by the above formula (1).

[0311] 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).

[0312] Specific examples of known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), and Moresco A20H (manufactured by Moresco).

[0313] The number average molecular weight of the known material used in combination with the lubricant of the present embodiment is preferably 1,000 to 10,000.

[0314] 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.

[0315] 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 chemical resistance and a high spin-off suppressing effect.

[0316] [Magnetic recording media]

[0317] 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.

[0318] 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.

[0319] Figure 1 It is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0320] 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 .

[0321] "Substrate"

[0322] 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.

[0323] 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.

[0324] "Attachment Layer"

[0325] 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.

[0326] 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.

[0327] "Soft magnetic layer"

[0328] 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.

[0329] Examples of the material of the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy.

[0330] 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 while reducing the floating amount of the magnetic head.

[0331] The soft magnetic layer 13 can be formed by, for example, sputtering.

[0332] "First Base Layer"

[0333] 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.

[0334] 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.

[0335] The first base layer 14 can be formed by, for example, sputtering.

[0336] "Second base layer"

[0337] 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.

[0338] 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.

[0339] The second base layer 15 can be formed by, for example, sputtering.

[0340] "Magnetic layer"

[0341] 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.

[0342] 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 .

[0343] The magnetic layer 16 may be composed of a single layer or a plurality of magnetic layers composed of materials having different compositions.

[0344] For example, when the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer, which are stacked in order 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.

[0345] The first magnetic layer may contain, in addition to Co, Cr, Pt, and oxides, one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re.

[0346] The second magnetic layer can be made of the same material as the first magnetic layer. The second magnetic layer preferably has a granular structure.

[0347] The third magnetic layer is preferably a non-granular structure composed 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.

[0348] When the magnetic layer 16 is formed of a plurality of magnetic layers, a non-magnetic layer is preferably provided between adjacent magnetic layers. When the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer, a non-magnetic layer is preferably provided between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.

[0349] 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.

[0350] 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 listed. As metal nitrides, for example, AlN, Si3N4, TaN, CrN, etc. can be listed. As metal carbides, for example, TaC, BC, SiC, etc. can be used.

[0351] The non-magnetic layer can be formed by, for example, sputtering.

[0352] 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.

[0353] 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.

[0354] "Protective layer"

[0355] The protective layer 17 protects the magnetic layer 16. The protective layer 17 may be composed of one layer or multiple layers. As the protective layer 17, a carbon protective layer may be preferably used, and an amorphous carbon protective layer is particularly preferred. If the protective layer 17 is a carbon 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 improved, so it is preferred.

[0356] 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. The hydrogen content in the carbon protective layer is preferably 3 atomic % to 20 atomic % when measured by hydrogen forward scattering (HFS). 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).

[0357] 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.

[0358] 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.

[0359] 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.

[0360] When a carbon-based protective layer is formed as the protective layer 17, the film formation can be performed by, for example, a DC magnetron sputtering method. In particular, when a carbon-based protective layer is formed as the protective layer 17, it is preferable to form an amorphous carbon protective layer by a plasma CVD method. The surface of the amorphous carbon protective layer formed by the plasma CVD method is uniform and has little roughness.

[0361] "Lubricating layer"

[0362] 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.

[0363] 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.

[0364] 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.

[0365] The average film thickness of the lubricating layer 18 is preferably More preferably If the average film thickness of the lubricating layer 18 is more than 0.5nm, the lubricating layer 18 will not become an island or a mesh shape but will be formed with a uniform film thickness. Therefore, the surface of the protective layer 17 can be coated with a high coverage rate by the lubricating layer 18. In addition, by setting the average film thickness of the lubricating layer 18 to less than 2.0nm, the lubricating layer 18 can be fully filmized, and the floating amount of the magnetic head can be fully reduced.

[0366] "Method for forming a lubricating layer"

[0367] Examples of a method for forming the lubricating layer 18 include preparing a magnetic recording medium in the process of manufacturing each layer including the protective layer 17 formed on the substrate 11 , applying a lubricating layer forming solution on the protective layer 17 , and drying the solution.

[0368] 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.

[0369] 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 Mitsui DuPont Fluorochemicals Co., Ltd.).

[0370] 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.

[0371] 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.

[0372] 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.

[0373] 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.

[0374] 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.

[0375] 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.

[0376] 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 chemical resistance and a good effect of inhibiting spin-off. Therefore, the reliability of the magnetic recording medium 10 of the present embodiment, especially the inhibition of silicon contamination and durability are excellent. Therefore, the magnetic recording medium 10 of the present embodiment can help reduce the magnetic spacing, and can work stably for a long time even in a harsh environment with a variety of uses. Therefore, the magnetic recording medium 10 of the present embodiment is particularly suitable as a magnetic disk mounted on a magnetic disk device of the LUL (Load Unload) method.

[0377] Example

[0378] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

[0379] [Example 1]

[0380] The compound represented by the above formula (AA) is obtained by the method shown below.

[0381] (First reaction)

[0382] Under nitrogen atmosphere, add HOCH2CF2O (CF2CF2O) into a 100 mL eggplant flask. h (CF2O) i 20 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), 4.12 g of a compound represented by the above formula (5-1), and 20 mL of tert-butanol were stirred at room temperature until uniform to form a mixture. 1.12 g of potassium tert-butoxide was added to the mixture, and the mixture was stirred at 70°C for 16 hours to react.

[0383] The compound represented by formula (5-1) is synthesized by protecting the hydroxyl group of ethylene glycol monoallyl ether with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0384] 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 9.74 g of a compound represented by the following formula (11) as an intermediate compound 1-1.

[0385]

[0386] Rf1 in formula (11) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization in Rf1 represents 4.5, and i representing the average degree of polymerization represents 4.5; THP represents tetrahydropyranyl.

[0387] (Second reaction)

[0388] Next, 9.61 g of the compound represented by formula (11) as the intermediate compound 1-1 obtained above, 0.75 g of the compound represented by formula (7-1) above, and 20 mL of tert-butanol were added to a 100 mL eggplant-shaped flask under a nitrogen atmosphere, and stirred at room temperature until uniform to form a mixture. 0.45 g of potassium tert-butoxide was added to the mixture, and stirred at 70° C. for 16 hours to react. The compound represented by formula (7-1) is synthesized by reacting one molecule of 1,3-propanediol with two molecules of epibromohydrin.

[0389] 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 3.38 g of compound (AA) (Rf1 in formula (AA) is the PFPE chain represented by the above formula (4-1). h representing the average degree of polymerization in the two Rf1s represents 4.5, and i representing the average degree of polymerization represents 4.5).

[0390] The obtained compound (AA) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0391] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(38H), 3.85-4.10(8H)

[0392] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0393] [Example 2]

[0394] The compound represented by the above formula (AB) is obtained by the method shown below.

[0395] The same operation as in Example 1 was carried out except that the compound represented by formula (7-2) was used instead of the compound represented by formula (7-1), thereby obtaining 3.43 g of compound (AB) (Rf1 in formula (AB) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0396] The compound represented by formula (7-2) is synthesized by reacting one molecule of ethylene glycol with two molecules of epibromohydrin.

[0397] The obtained compound (AB) is subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0398] 1 H-NMR (acetone-D6): δ[ppm]=3.40-3.85(38H), 3.85-4.10(8H)

[0399] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0400] [Example 3]

[0401] The compound represented by the above formula (AC) is obtained by the method shown below.

[0402] Except for using the compound represented by formula (7-3) instead of the compound represented by formula (7-1), the same operation as in Example 1 was carried out to obtain 3.43 g of compound (AC) (Rf1 in formula (AC) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0403] As the compound represented by formula (7-3), a commercially available product (manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0404] The obtained compound (AC) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0405] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(38H), 3.85-4.10(8H)

[0406] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0407] [Example 4]

[0408] The compound represented by the above formula (AD) is obtained by the method shown below.

[0409] Except for using the compound represented by formula (7-4) instead of the compound represented by formula (7-1), the same operation as in Example 1 was carried out to obtain 3.61 g of compound (AD) (Rf1 in formula (AD) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0410] The compound represented by formula (7-4) is synthesized by reacting one molecule of 1,6-hexanediol with two molecules of epibromohydrin.

[0411] The obtained compound (AD) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0412] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.85(8H), 3.40-3.85(38H), 3.85-4.10(8H)

[0413] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0414] [Example 5]

[0415] The compound represented by the above formula (AE) is obtained by the method shown below.

[0416] Except for using the compound represented by formula (7-5) instead of the compound represented by formula (7-1), the same operation as in Example 1 was carried out to obtain 3.68 g of compound (AE) (Rf1 in formula (AE) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0417] The compound represented by formula (7-5) is synthesized by reacting one molecule of 1,8-octanediol with two molecules of epibromohydrin.

[0418] The obtained compound (AE) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0419] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.85(12H), 3.40-3.85(38H), 3.85-4.10(8H)

[0420] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0421] [Example 6]

[0422] The compound represented by the above formula (AF) is obtained by the method shown below.

[0423] Except for using the compound represented by formula (7-6) instead of the compound represented by formula (7-1), the same operations as in Example 1 were carried out to obtain 3.52 g of compound (AF) (Rf1 in formula (AF) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0424] As the compound represented by the formula (7-6), a commercially available product (manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0425] The obtained compound (AF) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0426] 1H-NMR (acetone-D6): δ [ppm] = 0.90 (6H), 3.40-3.85 (38H), 3.85-4.10 (8H)

[0427] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0428] [Example 7]

[0429] The compound represented by the above formula (AG) is obtained by the method shown below.

[0430] The same operation as in Example 1 was performed except that the compound represented by formula (7-7) was used instead of the compound represented by formula (7-1), thereby obtaining 3.21 g of compound (AG) (Rf1 in formula (AG) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0431] The compound represented by formula (7-7) is synthesized by reacting one molecule of 2,3-butanediol with two molecules of epibromohydrin.

[0432] The obtained compound (AG) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0433] 1 H-NMR (acetone-D6): δ[ppm]=1.15-1.20(6H), 3.40-3.85(36H), 3.85-4.10(8H)

[0434] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0435] [Example 8]

[0436] The compound represented by the above formula (AH) is obtained by the method shown below.

[0437] The same operation as in Example 1 was performed except that the compound represented by formula (7-8) was used instead of the compound represented by formula (7-1), thereby obtaining 3.35 g of compound (AH) (Rf1 in formula (AH) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0438] The compound represented by the formula (7-8) is synthesized by reacting one molecule of dipropylene glycol with two molecules of epibromohydrin.

[0439] The obtained compound (AH) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0440] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(42H), 3.85-4.10(8H)

[0441] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0442] [Example 9]

[0443] The compound represented by the above formula (AI) is obtained by the method shown below.

[0444] The same operation as in Example 1 was performed except that the compound represented by formula (7-9) was used instead of the compound represented by formula (7-1), thereby obtaining 3.63 g of compound (AI) (Rf1 in formula (AI) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0445] The compound represented by the formula (7-9) is synthesized by reacting one molecule of diethylene glycol with two molecules of epibromohydrin.

[0446] The obtained compound (AI) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0447] 1 H-NMR (acetone-D6): δ[ppm]=, 3.40-3.85(42H), 3.85-4.10(8H)

[0448] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0449] [Example 10]

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

[0451] Except for using the compound represented by formula (7-10) instead of the compound represented by formula (7-1) in Example 1, the same operations as in Example 1 were carried out to obtain 3.81 g of compound (AJ) (Rf1 in formula (AJ) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0452] The compound represented by the formula (7-10) is synthesized by reacting one molecule of tetraethylene glycol with two molecules of epibromohydrin.

[0453] The obtained compound (AJ) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0454] 1 H-NMR (acetone-D6): δ[ppm]=3.40-3.85(50H), 3.85-4.10(8H)

[0455] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0456] [Example 11]

[0457] The compound represented by the above formula (BA) is obtained by the method shown below.

[0458] 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) iThe same operation as in Example 1 was carried out to obtain 3.49 g of compound (BA) (Rf2 in formula (BA) is the PFPE chain represented by the above formula (4-2). j representing the average degree of polymerization in the two Rf2s is 4.5).

[0459] The obtained compound (BA) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0460] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(38H), 3.85-4.10(8H)

[0461] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(36F), -86.4(8F), -124.3(8F), -130.0~-129.0(18F)

[0462] [Example 12]

[0463] The compound represented by the above formula (BB) is obtained by the method shown below.

[0464] 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 for the above to obtain 3.23 g of compound (BB) (Rf3 in formula (BB) is the PFPE chain represented by the above formula (4-3). k representing the average degree of polymerization in the two Rf3s is 3.0).

[0465] The obtained compound (BB) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0466] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(38H), 3.85-4.10(8H)

[0467] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(32F), -122.5(8F), -126.0(24F), -129.0~-128.0(8F)

[0468] [Example 13]

[0469] The compound represented by the above formula (BC) is obtained by the method shown below.

[0470] Except for using the compound represented by formula (5-2) instead of the compound represented by formula (5-1), the same operation as in Example 1 was carried out to obtain 3.45 g of compound (BC) (Rf1 in formula (BC) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0471] The compound represented by formula (5-2) is synthesized by protecting one hydroxyl group of 1,3-propanediol with dihydropyran and then reacting the protected group with epibromohydrin.

[0472] The obtained compound (BC) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0473] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(38H), 3.85-4.10(8H)

[0474] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0475] [Example 14]

[0476] The compound represented by the above formula (BD) is obtained by the method shown below.

[0477] Except that the compound represented by formula (5-3) was used instead of the compound represented by formula (5-1), the same operations as in Example 1 were carried out to obtain 3.12 g of compound (BD) (Rf1 in formula (BD) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0478] The compound represented by the formula (5-3) is synthesized by protecting 3-buten-1-ol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

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

[0480] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(30H), 3.85-4.10(8H)

[0481] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0482] [Example 15]

[0483] The compound represented by the above formula (BE) is obtained by the method shown below.

[0484] Except for using the compound represented by formula (5-4) instead of the compound represented by formula (5-1) in Example 1, the same operations as in Example 1 were carried out to obtain 3.34 g of compound (BE) (Rf1 in formula (BE) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0485] The compound represented by the formula (5-4) is synthesized by reacting 2-(2-bromoethoxy)tetrahydro-2H-pyran with 3-butene-1-ol and then oxidizing it with m-chloroperbenzoic acid.

[0486] The obtained compound (BE) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0487] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(38H), 3.85-4.10(8H)

[0488] 19F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0489] [Example 16]

[0490] The compound represented by the above formula (BF) is obtained by the method shown below.

[0491] The same operation as in Example 1 was performed except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), thereby obtaining 3.71 g of compound (BF) (Rf1 in formula (BF) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0492] The compound represented by the formula (5-5) is synthesized by subjecting the compound represented by the formula (5-1) to an addition reaction with allyl alcohol, followed by protection with dihydropyran, and further oxidation with m-chloroperbenzoic acid.

[0493] The obtained compound (BF) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0494] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(50H), 3.85-4.10(8H)

[0495] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0496] [Example 17]

[0497] The compound represented by the above formula (BG) is obtained by the method shown below.

[0498] The same operation as in Example 1 was performed except that the compound represented by formula (5-6) was used instead of the compound represented by formula (5-1), thereby obtaining 3.52 g of compound (BG) (Rf1 in formula (BG) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0499] The compound represented by the formula (5-6) is synthesized by subjecting the compound represented by the formula (5-3) to an addition reaction with allyl alcohol, followed by protection with dihydropyran, and further oxidation with m-chloroperbenzoic acid.

[0500] The obtained compound (BG) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0501] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(42H), 3.85-4.10(8H)

[0502] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0503] [Example 18]

[0504] The compound represented by the above formula (BH) is obtained by the method shown below.

[0505] The same operation as in Example 1 was performed except that the compound represented by formula (5-7) was used instead of the compound represented by formula (5-1), thereby obtaining 3.63 g of compound (BH) (Rf1 in formula (BH) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0506] The compound represented by the formula (5-7) is synthesized by subjecting the compound represented by the formula (5-1) to an addition reaction with 3-butene-1-ol, followed by protection with dihydropyran and further oxidation with m-chloroperbenzoic acid.

[0507] The obtained compound (BH) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0508] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(6H), 3.40-3.85(50H), 3.85-4.10(8H)

[0509] 19F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0510] [Example 19]

[0511] The compound represented by the above formula (BI) is obtained by the method shown below.

[0512] (First reaction)

[0513] The same operation as in the first reaction of Example 1 was carried out to obtain a compound represented by formula (11) as an intermediate compound 1a.

[0514] (Second reaction)

[0515] The same operation as in the first reaction of Example 1 was carried out except that the compound represented by formula (5-5) was used instead of the compound represented by formula (5-1), thereby obtaining a compound represented by formula (12) as an intermediate compound 1b.

[0516]

[0517] Rf1 in formula (12) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization in Rf1 represents 4.5, and i representing the average degree of polymerization represents 4.5; THP represents tetrahydropyranyl.

[0518] (Third reaction)

[0519] Next, in a nitrogen atmosphere, 9.66 g of the compound represented by formula (11) as the intermediate compound 1a obtained above, 0.69 g of the compound represented by formula (9-1) above, and 20 mL of tert-butanol were added to a 100 mL eggplant-shaped flask, and stirred at room temperature until uniform to form a mixture. 0.45 g of potassium tert-butoxide was added to the mixture, and stirred at 70°C for 16 hours to react. The compound represented by formula (9-1) was synthesized by reacting 1,3-propylene glycol with allyl bromide and epibromohydrin in sequence.

[0520] The reaction solution obtained above 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 oxidized with m-chloroperbenzoic acid and purified by silica gel column chromatography to obtain 7.58 g of the compound represented by the following formula (13) as an intermediate compound 1-2.

[0521]

[0522] Rf1 in formula (13) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization in Rf1 represents 4.5, and i representing the average degree of polymerization represents 4.5; THP represents tetrahydropyranyl.

[0523] (Fourth reaction)

[0524] Next, 7.35 g of the compound represented by formula (12) as the intermediate compound 1b obtained above, 7.58 g of the compound represented by formula (13) as the intermediate compound 1-2 obtained above, and 20 mL of tert-butanol were added to a 100 mL eggplant-shaped flask under a nitrogen atmosphere, and stirred at room temperature until uniform to form a mixture. 0.45 g of potassium tert-butoxide was added to the mixture, and stirred at 70° C. for 16 hours to react.

[0525] 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 4.54 g of compound (BI) (Rf1 in formula (BI) is the PFPE chain represented by the above formula (4-1). h representing the average degree of polymerization in the two Rf1s represents 4.5, and i representing the average degree of polymerization represents 4.5).

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

[0527] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(44H), 3.85-4.10(8H)

[0528] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0529] [Example 20]

[0530] The compound represented by the above formula (BJ) is obtained by the method shown below.

[0531] The same operation as in Example 1 was performed except that the compound represented by formula (5-8) was used instead of the compound represented by formula (5-1), thereby obtaining 3.67 g of compound (BJ) (Rf1 in formula (BJ) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0532] The compound represented by the formula (5-8) is synthesized by protecting one hydroxyl group of 1,6-hexanediol with dihydropyran and then reacting the protected hydroxyl group with epibromohydrin.

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

[0534] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.85(18H), 3.40-3.85(38H), 3.85-4.10(8H)

[0535] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0536] [Example 21]

[0537] The compound represented by the above formula (BK) is obtained by the method shown below.

[0538] Except that the compound represented by formula (5-9) was used instead of the compound represented by formula (5-1), the same operations as in Example 1 were carried out to obtain 3.48 g of compound (BK) (Rf1 in formula (BK) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0539] The compound represented by the formula (5-9) is synthesized by protecting 7-octen-1-ol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

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

[0541] 1H-NMR (acetone-D6): δ[ppm]=1.20-1.85(18H), 3.40-3.85(30H), 3.85-4.10(8H)

[0542] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0543] [Example 22]

[0544] The compound represented by the above formula (BL) is obtained by the method shown below.

[0545] Except that the compound represented by formula (5-10) was used instead of the compound represented by formula (5-1), the same operations as in Example 1 were carried out to obtain 3.02 g of compound (BL) (Rf1 in formula (BL) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0546] The compound represented by the formula (5-10) is synthesized by protecting 2-bromoethanol with dihydropyran, reacting it with 5-hexen-1-ol, and then oxidizing it with m-chloroperbenzoic acid.

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

[0548] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.85(14H), 3.40-3.85(38H), 3.85-4.10(8H)

[0549] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0550] [Example 23]

[0551] The compound represented by the above formula (BM) is obtained by the method shown below.

[0552] Except for using the compound represented by formula (5-11) instead of the compound represented by formula (5-1), the same operation as in Example 1 was carried out to obtain 3.14 g of compound (BM) (Rf1 in formula (BM) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0553] The compound represented by the formula (5-11) is synthesized by protecting allyl alcohol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0554] The obtained compound (BM) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0555] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(30H), 3.85-4.10(8H)

[0556] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0557] [Example 24]

[0558] The compound represented by the above formula (BN) is obtained by the method shown below.

[0559] Except for using the compound represented by formula (5-12) instead of the compound represented by formula (5-1), the same operation as in Example 1 was carried out to obtain 3.28 g of compound (BN) (Rf1 in formula (BN) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0560] The compound represented by formula (5-12) is synthesized by protecting the two hydroxyl groups of 1-allyloxy-2,3-propanediol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0561] The obtained compound (BN) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0562] 1H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(42H), 3.85-4.10(8H)

[0563] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0564] [Example 25]

[0565] The compound represented by the above formula (BO) is obtained by the method shown below.

[0566] Except for using the compound represented by formula (5-13) instead of the compound represented by formula (5-1), the same operation as in Example 1 was carried out to obtain 3.31 g of compound (BO) (Rf1 in formula (BO) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0567] The compound represented by formula (5-13) is synthesized by adding allyl alcohol to allyl glycidyl ether, protecting the generated hydroxyl group with dihydropyran, and then oxidizing one allyl group with m-chloroperbenzoic acid.

[0568] The obtained compound (BO) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0569] 1 H-NMR(acetone-D)6δ[ppm]=1.65-1.85(2H), 3.40-3.85(44H), 3.85-4.10(8H), 5.40-6.10(6H)

[0570] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0571] [Example 26]

[0572] The compound represented by the above formula (BP) is obtained by the method shown below.

[0573] Except for using the compound represented by formula (5-14) instead of the compound represented by formula (5-1), the same operation as in Example 1 was carried out to obtain 3.52 g of compound (BP) (Rf1 in formula (BP) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0574] The compound represented by the formula (5-14) is synthesized by allowing epibromohydrin to act on p-methoxyphenol.

[0575] The obtained compound (BP) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0576] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 3.40-3.85(34H), 3.85-4.10(8H), 6.30-7.10(8H)

[0577] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0578] [Example 27]

[0579] The compound represented by the above formula (BQ) is obtained by the method shown below.

[0580] Except for using the compound represented by formula (5-15) instead of the compound represented by formula (5-1) in Example 1, the same operations as in Example 1 were carried out to obtain 3.36 g of compound (BQ) (Rf1 in formula (BQ) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0581] The compound represented by the formula (5-15) is synthesized by reacting N-(2-hydroxyethyl)acetamide with epibromohydrin.

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

[0583] 1H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 1.90(6H), 3.40-3.85(36H), 3.85-4.10(8H), 6.30-6.50(2H)

[0584] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0585] [Example 28]

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

[0587] Except for using the compound represented by formula (5-16) instead of the compound represented by formula (5-1) in Example 1, the same operations as in Example 1 were carried out to obtain 3.57 g of compound (BR) (Rf1 in formula (BR) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0588] The compound represented by the formula (5-16) is synthesized by reacting 2-cyanoethanol with epibromohydrin.

[0589] The obtained compound (BR) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0590] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(2H), 2.00~2.10(4H), 3.40-3.85(32H), 3.85-4.10(8H)

[0591] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(18F), -78.5(4F), -80.5(4F), -91.0~-88.5(36F)

[0592] [Example 29]

[0593] The compound represented by the above formula (CA) is obtained by the method shown below.

[0594] The same operation as in Example 1 was carried out except that the compound represented by the following formula (14) was used instead of the compound represented by the formula (7-1), thereby obtaining 4.03 g of compound (CA) (Rf1 in the formula (CA) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0595]

[0596] Rf1 in formula (14) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization in Rf1 represents 4.5, and i representing the average degree of polymerization represents 4.5.

[0597] The compound represented by formula (14) is obtained by reacting HOCH2CF2O(CF2CF2O) h (CF2O) i The compound represented by CF2CH2OH (wherein h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5) (number average molecular weight 1000, molecular weight distribution 1.1) is reacted with the compound represented by formula (9-1), and then oxidized with m-chloroperbenzoic acid to synthesize the compound.

[0598] The obtained compound (CA) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0599] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(54H), 3.85-4.10(12H)

[0600] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0601] [Example 30]

[0602] The compound represented by the above formula (CB) is obtained by the method shown below.

[0603] Except for using the compound represented by formula (9-2) instead of the compound represented by formula (9-1), the same operations as in Example 29 were carried out to obtain 4.11 g of compound (CB) (Rf1 in formula (CB) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0604] The compound represented by formula (9-2) is synthesized by reacting ethylene glycol with allyl bromide and epibromohydrin in this order.

[0605] The obtained compound (CB) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0606] 1 H-NMR (acetone-D6): δ[ppm]=3.40-3.85(54H), 3.85-4.10(12H)

[0607] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0608] [Example 31]

[0609] The compound represented by the above formula (CC) is obtained by the method shown below.

[0610] Except for using the compound represented by formula (9-5) instead of the compound represented by formula (9-1), the same operations as in Example 29 were carried out to obtain 4.32 g of compound (CC) (Rf1 in formula (CC) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0611] The compound represented by formula (9-5) is synthesized by reacting 1,8-octanediol with allyl bromide and epibromohydrin in this order.

[0612] The obtained compound (CC) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0613] 1 H-NMR (acetone-D6): δ[ppm]=1.20-1.85(24H), 3.40-3.85(54H), 3.85-4.10(12H)

[0614] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0615] [Example 32]

[0616] The compound represented by the above formula (CD) is obtained by the method shown below.

[0617] Except for using the compound represented by formula (9-6) instead of the compound represented by formula (9-1), the same operations as in Example 29 were carried out to obtain 4.21 g of compound (CD) (Rf1 in formula (CD) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0618] The compound represented by formula (9-6) is synthesized by reacting 2,2-dimethyl-1,3-propanediol with allyl bromide and epibromohydrin in this order.

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

[0620] 1 H-NMR (acetone-D6): δ [ppm] = 0.90 (12H), 3.40-3.85 (54H), 3.85-4.10 (12H)

[0621] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0622] [Example 33]

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

[0624] Except that the compound represented by formula (9-7) was used instead of the compound represented by formula (9-1), the same operations as in Example 29 were performed to obtain 3.96 g of compound (CE) (Rf1 in formula (CE) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0625] The compound represented by formula (9-7) is synthesized by reacting 2,3-butanediol with allyl bromide and epibromohydrin in this order.

[0626] The obtained compound (CE) was subjected to 1 H-NMR determination and 19The structure was identified based on the following results from F-NMR measurement.

[0627] 1 H-NMR (acetone-D6): δ[ppm]=1.15-1.20(12H), 3.40-3.85(50H), 3.85-4.10(12H)

[0628] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0629] [Example 34]

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

[0631] Except for using the compound represented by formula (9-9) instead of the compound represented by formula (9-1), the same operations as in Example 29 were carried out to obtain 4.35 g of compound (CF) (Rf1 in formula (CF) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0632] The compound represented by formula (9-9) is synthesized by reacting diethylene glycol with allyl bromide and epibromohydrin in this order.

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

[0634] 1 H-NMR (acetone-D6): δ[ppm]=3.40-3.85(62H), 3.85-4.10(12H)

[0635] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0636] [Example 35]

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

[0638] In the synthesis of the compound represented by formula (11) and the compound represented by formula (14), HOCH2CF2CF2O (CF2CF2CF2O) is used respectively. 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 same operation as in Example 29 was carried out to obtain 4.25 g of compound (DA) (Rf2 in formula (DA) is the PFPE chain represented by the above formula (4-2). j representing the average degree of polymerization among the three Rf2s is 4.5).

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

[0640] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(54H), 3.85-4.10(12H)

[0641] 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(54F), -86.4(12F), -124.3(12F), -130.0~-129.0(27F)

[0642] [Example 36]

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

[0644] Except for using the compound represented by formula (5-5) instead of the compound represented by formula (5-1), the same operations as in Example 29 were carried out to obtain 4.41 g of compound (DB) (Rf1 in formula (DB) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

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

[0646] 1H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(66H), 3.85-4.10(12H)

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

[0648] [Example 37]

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

[0650] Except for using the compound represented by formula (5-3) instead of the compound represented by formula (5-1), the same operations as in Example 29 were carried out to obtain 3.81 g of compound (DC) (Rf1 in formula (DC) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0651] The obtained compound (DC) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0652] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(46H), 3.85-4.10(12H)

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

[0654] [Example 38]

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

[0656] Except for using the compound represented by formula (5-4) instead of the compound represented by formula (5-1), the same operations as in Example 29 were carried out to obtain 4.07 g of compound (DD) (Rf1 in formula (DD) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

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

[0658] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(8H), 3.40-3.85(54H), 3.85-4.10(12H)

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

[0660] [Example 39]

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

[0662] Except for using the compound represented by formula (5-15) instead of the compound represented by formula (5-1), the same operations as in Example 29 were carried out to obtain 4.18 g of compound (DE) (Rf1 in formula (DE) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

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

[0664] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 1.90(6H), 3.40-3.85(52H), 3.85-4.10(12H), 6.30-6.50(2H)

[0665] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0666] [Example 40]

[0667] The compound represented by the above formula (DF) is obtained by the method shown below.

[0668] Except for using the compound represented by formula (5-16) instead of the compound represented by formula (5-1), the same operations as in Example 29 were carried out to obtain 4.32 g of compound (DF) (Rf1 in formula (DF) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

[0669] The obtained compound (DF) was subjected to 1 H-NMR determination and 19 The structure was identified based on the following results from F-NMR measurement.

[0670] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 2.00~2.10(4H), 3.40-3.85(48H), 3.85-4.10(12H)

[0671] 19 F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0672] [Example 41]

[0673] The compound represented by the above formula (DG) is obtained by the method shown below.

[0674] Except for using the compound represented by formula (5-11) instead of the compound represented by formula (5-1), the same operations as in Example 29 were carried out to obtain 3.86 g of compound (DG) (Rf1 in formula (DG) is the PFPE chain represented by the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5).

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

[0676] 1 H-NMR (acetone-D6): δ[ppm]=1.65-1.85(4H), 3.40-3.85(46H), 3.85-4.10(12H)

[0677] 19F-NMR (acetone-D6): δ[ppm]=-55.5~-51.5(27F), -78.5(6F), -80.5(6F), -91.0~-88.5(54F)

[0678] The compounds (AA) to (AJ), (BA) to (BR), (CA) to (CF), and (DA) to (DG) of Examples 1 to 41 thus obtained correspond to the values ​​of x, R 1 , R 2 , R 3 , R 4 The structures of are shown in Table 1. It should be noted that, except for compound (BI), all are R 1 and R 4 The structure is the same.

[0679] Table 1

[0680]

[0681] Table 2

[0682]

[0683] [Comparative Example 1]

[0684] According to the method described in Patent Document 1, a compound represented by the following formula (ZA) was synthesized.

[0685]

[0686] Rf1 in formula (ZA) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization in two Rf1s represents 7.0, and i representing the average degree of polymerization represents 0.

[0687] [Comparative Example 2]

[0688] According to the method described in Patent Document 2, a compound represented by the following formula (ZB) was synthesized.

[0689]

[0690] Rf1 in formula (ZB) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization of the two Rf1s is 4.5, and i representing the average degree of polymerization is 4.5.

[0691] [Comparative Example 3]

[0692] According to the method described in Patent Document 3, a compound represented by the following formula (ZC) was synthesized.

[0693]

[0694] Rf1 in the formula (ZC) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization of the two Rf1s is 4.5, and i representing the average degree of polymerization is 4.5.

[0695] [Comparative Example 4]

[0696] According to the method described in Patent Document 4, a compound represented by the following formula (ZD) was synthesized.

[0697]

[0698] Rf2 in the formula (ZD) is the PFPE chain represented by the above formula (4-2); j representing the average degree of polymerization in the two Rf2s is 4.5.

[0699] [Comparative Example 5]

[0700] According to the method described in Patent Document 5, a compound represented by the following formula (ZE) was synthesized.

[0701]

[0702] Rf1 in the formula (ZE) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization among the three Rf1s is 7.0, and i representing the average degree of polymerization is 0.

[0703] [Comparative Example 6]

[0704] According to the method described in Patent Document 6, a compound represented by the following formula (ZF) was synthesized.

[0705]

[0706] Rf1 in the formula (ZF) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization of the two Rf1s is 4.5, and i representing the average degree of polymerization is 4.5.

[0707] [Comparative Example 7]

[0708] According to the method described in Patent Document 7, a compound represented by the following formula (ZG) was synthesized.

[0709]

[0710] Rf1 in the formula (ZG) is the PFPE chain represented by the above formula (4-1); h representing the average degree of polymerization of the two Rf1s is 4.5, and i representing the average degree of polymerization is 4.5.

[0711] The number average molecular weight (Mn) of the compounds of Examples 1 to 41 and Comparative Examples 1 to 7 thus obtained was measured by the above-mentioned method.

[0712] Next, a lubricant layer forming solution was prepared by the method shown below using the compounds obtained in Examples 1 to 41 and Comparative Examples 1 to 7. 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 41 and Comparative Examples 1 to 7.

[0713] "Lubricating layer forming solution"

[0714] The compounds obtained in Examples 1 to 41 and Comparative Examples 1 to 7 were respectively dissolved in a fluorine-based solvent, Batler (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.), and the films were coated on the protective layer to a thickness of The mixture was diluted with Batler XF in a manner of 1:1 to prepare a lubricating layer forming solution.

[0715] "Magnetic recording media"

[0716] 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.

[0717] 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 41 and Comparative Examples 1 to 7 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.

[0718] 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.

[0719] (Film thickness measurement)

[0720] 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).

[0721] Next, the magnetic recording media of Examples 1 to 41 and Comparative Examples 1 to 7 were subjected to the chemical resistance test and spin-off characteristic test described below.

[0722] [Chemical resistance test]

[0723] The following method is used to evaluate the degree of contamination of the magnetic recording medium by environmental substances that generate contaminants in a high temperature environment. Si ions are used as environmental substances. The degree of contamination of the magnetic recording medium caused by the contaminants generated by the environmental substances is evaluated by measuring the amount of Si adsorption as the amount of the contaminants.

[0724] Specifically, in the presence of siloxane-based Si rubber, the magnetic recording medium to be evaluated was kept in a high temperature environment of 85°C and 0% humidity for 240 hours. Next, the Si adsorption amount present on the surface of the magnetic recording medium was determined using secondary ion mass spectrometry (SIMS), and the degree of contamination caused by Si ions was evaluated as the Si adsorption amount. The evaluation of the degree of contamination was performed using the numerical value when the result of the Si adsorption amount of Comparative Example 5 was designated as 1.00, and was evaluated based on the following evaluation criteria. The results are shown in Tables 3 and 4.

[0725] "Evaluation criteria for chemical resistance"

[0726] A+: Si adsorption is less than 0.60

[0727] A: Si adsorption amount is 0.60 or more and less than 0.70

[0728] B: Si adsorption amount is 0.70 or more and less than 0.90

[0729] C: Si adsorption amount is 0.90 or more and less than 1.10

[0730] D: Si adsorption amount is 1.10 or more

[0731] [Spin-off characteristics test]

[0732] The magnetic recording medium was mounted on a rotating frame and rotated at a rotation speed of 10,000 rpm for 72 hours in an environment of 80°C. Before and after this operation, the film thickness of the lubricating layer at a radius of 20 mm from the center of the magnetic recording medium was measured using FT-IR, and the film thickness reduction rate of the lubricating layer before and after the test was calculated. Using the calculated film thickness reduction rate, the spin-off characteristics were evaluated according to the evaluation criteria shown below.

[0733] "Evaluation criteria for spin-off characteristics"

[0734] A+: Film thickness reduction rate is less than 2%

[0735] A: Film thickness reduction rate is 2% or more and less than 3%

[0736] B: Film thickness reduction rate is 3% or more and less than 5%

[0737] C: Film thickness reduction rate is 5% or more and less than 10%

[0738] D: Film thickness reduction rate is more than 10%

[0739] [Comprehensive evaluation]

[0740] Based on the results of the chemical resistance test and the spin-off characteristics test, comprehensive evaluation was performed based on the following criteria.

[0741] “Comprehensive evaluation”

[0742] A: The chemical resistance test and the spin-off characteristics test were both rated A+ or A

[0743] B: One of the chemical resistance test and the spin-off characteristics test is B, and the other is A+, A, or B

[0744] C: One of the chemical resistance test and the spin-off characteristics test is C, and the other is A+, A, B, or C

[0745] D: At least one of the evaluation in the chemical resistance test and the evaluation in the spin-off characteristics test is D

[0746] Table 3

[0747]

[0748] Table 4

[0749]

[0750] As shown in Tables 3 and 4, R 3 The magnetic recording media of Examples 1 to 41, which are fluorinated ether compounds (AA) to (AJ), (BA) to (BR), (CA) to (CF), (DA) to (DG) having a divalent linking group represented by formula (2-1) or formula (2-2) and satisfying formula (1), were evaluated as any one of A+, A, and B in all evaluation items of the chemical resistance test and the spin-off characteristic test. It can be confirmed that the lubricating layer of the magnetic recording media of Examples 1 to 41 has good chemical resistance and good spin-off suppression effect.

[0751] The R 1 and R 4 is a terminal group represented by formula (3-1), p is 0, q is 0, r is 1, R 2 The compounds (AA) to (AJ) and (CA) to (CF) of the perfluoropolyether chain represented by the formula (4-1) were compared in Examples 1 to 10 and 29 to 34. 3Among the compounds having a connecting group represented by formula (2-1), in Examples 1, 3 to 7, 29, 31 to 33 of compound (AA), compounds (AC) to (AG), compound (CA) and compounds (CC) to (CE) in which the number of carbon atoms contained in Y in formula (2) is 3 or more, the evaluation in the chemical resistance test was A+, showing good results.

[0752] When using R 3 In Examples 8 to 10 and 34 of Compounds (AH) to (AJ) and Compound (CF) having a linking group represented by Formula (2-2), the evaluation of the spin-off characteristic test was A+, showing a good result.

[0753] On the other hand, in Comparative Examples 1 to 7 using compounds (ZA) to (ZG), the evaluations were C or D in all evaluation items of the chemical resistance test and the spin-off characteristic test, and the overall evaluations were all C or D.

[0754] In more detail, in the compound (ZA) used in Comparative Example 1 and the compound (ZB) used in Comparative Example 2, the hydroxyl group contained in the connecting group part between the perfluoropolyether chains is only one. Therefore, sufficient interaction between the connecting group part and the protective layer cannot be obtained, and the central part of the fluorinated ether compound will float and easily be involved in pollutants, so the result of the chemical resistance test is D. In addition, in compounds (ZA) and (ZB), bulky perfluoropolyether chains are arranged on both sides of the glycerol structure. Therefore, it is believed that the free movement of the hydroxyl group of the glycerol structure is hindered, and the hydroxyl group becomes difficult to participate in the interaction with the active point on the protective layer or the polar group in other fluorinated ether compounds present in the lubricating layer, and the evaluation of the spin-off characteristic test is D.

[0755] In addition, the compound (ZF) used in Comparative Example 6 and the compound (ZG) used in Comparative Example 7 have 2 or 3 hydroxyl groups in the linking group between the perfluoropolyether chains. However, in the compounds (ZF) and (ZG), since the two glycerol structures are bonded via the unit containing the rigid ring structure, the movement of the hydroxyl group is restricted by the rigid ring structure. Therefore, sufficient interaction between the linking group part and the protective layer cannot be obtained, and the central part of the fluorinated ether compound floats and is easily involved in contaminants, so the result of the chemical resistance test is C or D.

[0756] The two hydroxyl groups contained in the linking groups of the compound (ZC) used in Comparative Example 3 and the compound (ZD) used in Comparative Example 4 were bonded only via a rigid alkylene chain. Therefore, it is considered that the free movement of the hydroxyl groups contained in the linking group was hindered, and the hydroxyl groups became difficult to participate in the interaction with the active points on the protective layer or the polar groups in other fluorinated ether compounds present in the lubricating layer, and the evaluation of the spin-off characteristic test was D.

[0757] In addition, in the compound (ZE) used in Comparative Example 5, the perfluoropolyether chains are bonded via a linking group having two hydroxyl groups. However, since the distance between the two hydroxyl groups of the linking group is close, the two hydroxyl groups of the linking group are likely to interact with each other in the molecule. Therefore, it is considered that the two hydroxyl groups of the linking group become difficult to participate in the interaction with the polar groups contained in other fluorine-containing ether compound molecules present in the lubricating layer, and the evaluations of the chemical resistance test and the spin-off characteristic test were C.

[0758] Industrial Applicability

[0759] By using the lubricant for a magnetic recording medium containing the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer which has excellent chemical resistance and a high spin-off suppressing effect even if the thickness is thin.

[0760] Explanation of symbols

[0761] 10···magnetic recording medium, 11···substrate, 12···adhesion layer, 13···soft magnetic layer, 14···first base layer, 15···second base layer, 16···magnetic layer, 17···protective layer, 18···lubricating layer.

Claims

1. A fluorine-containing ether compound, characterized in that It is represented by the following formula (1): R 1 -CH2-R 2 [-CH2-R 3 -CH2-R 2 ] x -CH2-R 4 (1) In formula (1), x represents an integer of 1 to 2; R 2 is a perfluoropolyether chain; (x+1) R 2 They may be partially or completely the same, or they may be different; R 3 is a divalent linking group represented by the following formula (2); when x is 2, the two R 3 Can be the same or different; R 1 and R 4 is a terminal group having 1 to 4 polar groups and 1 to 50 carbon atoms; R 1 and R 4 They can be the same or different; In the formula (2), Y represents an acyclic divalent saturated hydrocarbon group having 2 to 8 carbon atoms which may have an ether oxygen atom between carbon atoms.

2. The fluorine-containing ether compound according to claim 1, wherein the formula (2) is a linking group represented by the following formula (2-1) or (2-2), In formula (2-1), a represents an integer of 2 to 8; a R a and R b Each independently represents a hydrogen atom or a methyl group; a (-CR a R b -) contains 2 to 8 carbon atoms; the oxygen atom at the left terminal of formula (2-1) 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 (2-2), b represents an integer of 2 to 4; b R c Each independently represents -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2- or -CH2CH(CH3)-; b R c The total number of carbon atoms contained in is 4 to 8; the oxygen atom at the left end of formula (2-2) 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.

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 following formula (3), In formula (3), I represents an integer of 1 to 3, I m each independently represents an integer of 1 to 6, I n each independently represents an integer of 1 to 6, in one repeating unit, at least one of m and n is 1, and A represents an alkyl group that may have a polar group, an organic group that may have a polar group and contains a carbon-carbon unsaturated bond, or a hydrogen atom.

4. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 and R 4 Each independently represents 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 1 to 5, the total value of p and r is 1 to 5, and B represents a polar group; In the formula (3-2), s represents an integer of 0-2, and t represents an integer of 1-5.

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

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

7. The fluorinated ether compound according to claim 1 or 2, wherein R in the formula (1) 1 The polar groups and R 4 All polar groups are hydroxyl groups.

8. The fluorinated ether compound according to claim 1 or 2, wherein the (x+1) R in the formula (1) 2 Each independently is a perfluoropolyether chain represented by the following formula (4), -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4) In formula (4), w2, w3, w4, and w5 represent the average degree of polymerization, and each independently represents 0 to 20; however, 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 (4) is not particularly limited.

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

10. 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.

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

12. A magnetic recording medium comprising at least a magnetic layer, a protective layer and a lubricating layer provided in sequence on a substrate, The lubricating layer comprises the fluorine-containing ether compound according to claim 1 or 2. 13 . The magnetic recording medium according to claim 12 , wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm.

Images