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

Abstract

We provide fluorinated ether compounds that can form a lubricating layer with excellent wear resistance even when thin, and with minimal reduction in film thickness due to shedding. The fluorinated ether compound is represented by the following formula: R 1 -R 2 -O-CH2-R 3 -CH2-O-R 4 -R 5 (R 3 It is a perfluoropolyether chain. R 1 and R 5 R can be any of the following: alkyl groups that may have substituents, or hydrocarbon groups that have double or triple bonds. 2 and R 4 Each is a divalent linker containing one or more heteroatoms, has one or more polar groups, and is associated with R. 1 and R 5 The terminal part of the bonding side is a heteroatom. R 2 and R 4 At least one of them contains more than one secondary amine structure. R 1 -R 2 - and -R 4 -R 5 (At least one of them has one or more cyano groups).

Description

Technical Field

[0001] This invention relates to fluorinated ether compounds, lubricants for magnetic recording media, and magnetic recording media.

[0002] This application claims priority based on Japanese Patent Application No. 2021-107598 filed on June 29, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] In order to improve the recording density of magnetic recording reproduction devices, it is necessary to develop magnetic recording media suitable for high recording density.

[0004] Conventionally, magnetic recording media have consisted of materials with a recording layer formed on a substrate and a protective layer, such as carbon, formed on the recording layer. The protective layer protects the information recorded on the recording layer and improves the smoothness of the magnetic head. However, simply providing a protective layer on the recording layer is insufficient to achieve adequate durability of the magnetic recording medium. Therefore, generally, a lubricant is applied to the surface of the protective layer to form a lubricating layer.

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

[0006] For example, Patent Document 1 discloses a fluorinated ether compound in which a divalent linker with a polar group is attached to both ends of a perfluoropolyether chain, and at least one of the links is a terminal group in which one or more hydrogen atoms of an organic group having 1 to 8 carbon atoms are replaced by a cyano group.

[0007] Furthermore, Patent Document 2 discloses a polyether compound having an amino alcohol group introduced at the end of the molecular chain of a perfluoropolyether.

[0008] Furthermore, Patent Document 3 discloses a fluorinated ether compound in which a linker obtained by combining an ether bond (-O-), a methylene group (-CH2-), and a methylene group with one hydrogen atom replaced by a hydroxyl group (-CH(OH)-) is configured between the perfluoropolyether chain and the two end groups.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: International Publication No. 2019 / 039200

[0012] Patent Document 2: Japanese Patent Application Publication No. 11-131083

[0013] Patent Document 3: International Publication No. 2019 / 054148 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] In magnetic recording playback devices, there is a further requirement to minimize the upward movement of the magnetic head. Therefore, it is necessary to make the lubricating layer in the magnetic recording medium thinner. However, generally speaking, if the lubricating layer is thinner, there is a tendency for the wear resistance of the magnetic recording medium to decrease.

[0016] As a method to maintain sufficient wear resistance while achieving a thin lubricating film, the use of lubricants with a low average molecular weight can be considered. However, lubricating layers formed using lubricants with low average molecular weight are prone to peeling off.

[0017] In recent years, with the rapid increase in recording density of magnetic recording media, the rotation speed of magnetic recording media has also increased. If the magnetic recording media is rotated at high speed, lubricant may sometimes scatter due to centrifugal force during rotation, or evaporate due to the heat generated during rotation. This phenomenon is called shedding.

[0018] If detachment occurs, the thickness of the lubricating layer decreases, thus slowly reducing its wear resistance. As a result, in the worst case, this can lead to damage to the magnetic recording medium due to contact with the magnetic head (head impact). Using a lubricant with a high average molecular weight is an effective method to suppress detachment, maintain the wear resistance of the lubricating layer, and improve the durability of the magnetic recording medium.

[0019] The present invention was made in view of the above circumstances, and its object is to provide a fluorinated ether compound that can form a lubricating layer that has excellent wear resistance even when the thickness is thin and is not prone to film thickness reduction due to peeling, and is suitable for use as a lubricant for magnetic recording media.

[0020] Furthermore, the object of the present invention is to provide a lubricant for magnetic recording media comprising the fluorinated ether compound of the present invention.

[0021] Furthermore, the object of the present invention is to provide a magnetic recording medium having excellent reliability and durability, having a lubricating layer comprising the fluorinated ether compound of the present invention.

[0022] Methods for solving problems

[0023] In order to solve the above-mentioned problems, the inventor has repeatedly conducted in-depth research.

[0024] The results showed that the present invention could be conceived simply by preparing a fluorinated ether compound having a structure in which terminal groups are attached to both ends of a perfluoropolyether chain via linkers, at least one of the linkers at both ends having a secondary amine structure (-NH-), and at least one of the structures in which the linkers and terminal groups at both ends are attached having a cyano group (-CN).

[0025] That is, the present invention relates to the following matters.

[0026] [1] A fluorinated ether compound, characterized by being represented by the following formula (1).

[0027] R 1 -R 2 -O-CH2-R 3 -CH2-OR 4 -R 5 (1)

[0028] (In equation (1), R) 3 It is a perfluoropolyether chain. R 1 and R 5 Each is independently a terminal group composed of any of the following: an alkyl group that may have substituents, or a hydrocarbon group having a double or triple bond. R 2 and R 4 Each is a divalent linker containing one or more heteroatoms, has one or more polar groups, and is associated with R. 1 and R 5 The terminal part of the bonding side is a heteroatom. R 2 and R 4 At least one of them contains more than one secondary amine structure. R 1 -R 2 -and-R 4 -R 5 (At least one of them has one or more cyano groups.)

[0029] [2] According to the fluorinated ether compound described in [1], the above R 2 and R 4 The polar group is selected from any one of secondary amine structures, hydroxyl and cyano groups.

[0030] [3] According to the fluorinated ether compound described in [1], in the above formula (1), -R 2 -O- is represented by the following formula (2), -OR 4 - It is represented by the following formula (3).

[0031] -[A] a [B] d -O- (2)

[0032] -O-[C] g [D] j - (3)

[0033] (In equation (2), [A] is represented by equation (4-1) below, and [B] is represented by equation (4-2) below. In equation (2), the order of [A] and [B] can be interchanged. a is an integer from 0 to 3, d is an integer from 0 to 3, and at least one of a and d is 1 or higher. The end -CH2- on the opposite side of X in equation (4-1) or the end -CH2- on the opposite side of X in (4-2) combines with -O- in equation (2).)

[0034] (In equation (3), [C] is represented by equation (5-1) below, and [D] is represented by equation (5-2) below. The order of [C] and [D] in equation (3) can be interchanged. g is an integer from 0 to 3, j is an integer from 0 to 3, and at least one of g and j is 1 or higher. The end -CH2- on the opposite side of X in equation (5-1) or the end -CH2- on the opposite side of X in (5-2) combines with -O- in equation (3).)

[0035]

[0036] (In equation (4-1), b and c are integers from 0 to 4. In equation (4-2), e and f are integers from 0 to 4. In equation (5-1), h and i are integers from 0 to 4. In equation (5-2), k and l are integers from 0 to 4. In equations (4-1), (4-2), (5-1), and (5-2), X is 0 or NH. In equations (4-1), (4-2), (5-1), and (5-2), more than one of X is NH.)

[0037] [4] The fluorinated ether compound according to any one of [1] to [3] contains two or more secondary amine structures in its molecule.

[0038] [5] The fluorinated ether compound according to any one of [1] to [4] contains 3 or fewer hydroxyl groups in its molecule.

[0039] [6] The fluorinated ether compound according to any one of [1] to [5] contains 3 or fewer cyano groups in its molecule.

[0040] [7] The fluorinated ether compound according to any one of [1] to [6] contains a molecule containing a secondary amine structure and a hydroxyl group and a cyano group totaling 8 or less.

[0041] [8] The fluorinated ether compound according to any one of [1] to [7] contains 2 or more secondary amine structures, 3 or fewer hydroxyl groups, 3 or fewer cyano groups, and the total number of secondary amine structures, hydroxyl groups and cyano groups is 8 or fewer.

[0042] [9] The fluorinated ether compound according to any one of [1] to [8], wherein -R in the above formula (1) 2 -O- can be any one of the following formulas (11-1) to (11-12).

[0043]

[0044]

[0045]

[10] In any one of [1] to [9], the alkyl group that may have a substituent is an alkyl group having a hydroxyl or a cyano group.

[0046]

[11] In any one of the fluorinated ether compounds according to [1] to

[10] , the hydrocarbon group having a double or triple bond is any one of an aromatic hydrocarbon group, an aromatic heterocyclic group, an alkenyl group, and an alkynyl group.

[0047]

[12] According to any one of [1] to

[11] , R in the above formula (1) 3 It is any one of the following formulas (6) to (10).

[0048] -CF₂O-(CF₂CF₂O) m -(CF2O) n -CF2- (6)

[0049] (In equation (6), m and n represent the average degree of polymerization, each ranging from 0.1 to 30.)

[0050] -CF₂O-(CF₂CF₂O) w -CF2- (7)

[0051] (In equation (7), w represents the average degree of polymerization, ranging from 0.1 to 30.)

[0052] -CF2CF2O-(CF2CF2CF2O) x -CF2CF2- (8)

[0053] (x in equation (8) represents the average degree of polymerization, ranging from 0.1 to 30.)

[0054] -CF2CF2CF2O-(CF2CF2CF2CF2O) y -CF2CF2CF2- (9)

[0055] (In equation (9), y represents the average degree of polymerization, ranging from 0.1 to 30.)

[0056] -CF(CF3)-(OCF(CF3)CF2) z -OCF(CF3)- (10)

[0057] (In equation (10), z represents the average degree of polymerization, ranging from 0.1 to 30.)

[0058]

[13] According to the fluorinated ether compound described in [1], the compound represented by the above formula (1) is any one of the compounds represented by the following formulas (A), (J), (P), (Q) and (U).

[0059]

[0060] (In formula (A), ma and na represent the average degree of polymerization, where ma represents 1 to 30 and na represents 0.1 to 30.)

[0061] (In formula (J), mj and nj represent the average degree of polymerization, where mj represents 1 to 30 and nj represents 0.1 to 30.)

[0062] (In formula (P), mp and np represent the average degree of polymerization, where mp represents 1 to 30 and np represents 0.1 to 30.)

[0063]

[0064] (In equation (Q), mq and nq represent the average degree of polymerization, where mq represents 1 to 30 and nq represents 0.1 to 30.)

[0065] (In formula (U), mu and nu represent the average degree of polymerization, where mu represents 1 to 30 and nu represents 0.1 to 30.)

[0066]

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

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

[0067]

[15] A lubricant for magnetic recording media, characterized in that it comprises any one of [1] to

[14] a fluorinated ether compound.

[0068]

[16] A magnetic recording medium, characterized in that it is a magnetic recording medium on a substrate having at least a magnetic layer, a protective layer, and a lubricating layer disposed sequentially.

[0069] The above-mentioned lubricating layer contains any one of the fluorinated ether compounds described in [1] to

[14] .

[0070]

[17] According to the magnetic recording medium described in

[16] , the average film thickness of the above-mentioned lubricating layer is 0.5 nm to 2.0 nm.

[0071] The effects of the invention

[0072] The fluorinated ether compound of the present invention is the compound shown in formula (1) above, and is suitable as a material for a lubricant for magnetic recording media.

[0073] The lubricant for magnetic recording media of the present invention contains the fluorinated ether compound of the present invention, thus enabling the formation of a lubricating layer that exhibits excellent wear resistance even when thin and is less prone to film thickness reduction due to shedding.

[0074] The magnetic recording medium of the present invention has excellent reliability and durability because it is provided with a lubricating layer containing the fluorinated ether compound of the present invention, which has excellent wear resistance and shedding resistance. Attached Figure Description

[0075] Figure 1 A schematic cross-sectional view illustrating an example of an embodiment of the magnetic recording medium of the present invention. Detailed Implementation

[0076] The following provides a detailed description of preferred examples of the fluorinated ether compound, the lubricant for magnetic recording media (hereinafter sometimes abbreviated as "lubricant"), and the magnetic recording media of the present invention. Furthermore, the present invention is not limited to the embodiments shown below. The present invention is not limited to the examples shown below; additions, omissions, substitutions, and modifications can be made to the numbers, quantities, ratios, compositions, types, positions, materials, and structures without departing from the spirit of the present invention.

[0077] [Fluoroether compounds]

[0078] The fluorinated ether compound in this embodiment is represented by the following formula (1).

[0079] R 1 -R 2 -O-CH2-R 3 -CH2-OR 4 -R 5 (1)

[0080] (In equation (1), R) 3 It is a perfluoropolyether chain. R 1 and R 5 Each is independently a terminal group composed of any of the following: an alkyl group that may have substituents, or a hydrocarbon group having a double or triple bond. R 2 and R 4 Each is a divalent linker containing one or more heteroatoms, possessing one or more polar groups, and connected with R. 1and R 5 The terminal part of the bonding side is a heteroatom. R 2 and R 4 At least one of them contains more than one secondary amine structure. R 1 -R 2 -and-R 4 -R 5 (At least one of them has one or more cyano groups.)

[0081] Here, the reason why, even with a thin layer, excellent wear resistance and detachment resistance can be obtained when a lubricating layer is formed on the protective layer of the magnetic recording medium using a lubricant containing a fluorinated ether compound of this embodiment is used.

[0082] The fluorinated ether compound of this embodiment is as shown in formula (1), having R 3 The perfluoropolyether chain shown is sometimes abbreviated as "PFPE chain" below. The PFPE chain covers the surface of the protective layer in the lubricating layer containing the fluorinated ether compound of this embodiment, and imparts lubricity to the lubricating layer, thereby reducing the friction between the magnetic head and the protective layer.

[0083] Furthermore, the R of the fluorinated ether compound shown in formula (1) 2 and R 4 Each is a divalent linker containing one or more heteroatoms and has one or more polar groups. Furthermore, R 2 and R 4 At least one of them contains one or more secondary amine structures (-NH-). R 2 and R 4 The polar groups contained therein, and R 2 and R 4 The secondary amine structure, which is a polar group, contained in at least one of the components in the lubricant containing the fluorinated ether compound of this embodiment, causes the fluorinated ether compound to adhere tightly to the protective layer, thereby improving wear resistance.

[0084] The secondary amine structure (-NH-) of the fluorinated ether compound shown in Formula (1) is polar, exhibiting both interaction (affinity) with the protective layer and intramolecular interaction. The interaction of the secondary amine structure with the protective layer is equivalent to that of the hydroxyl group. However, the intramolecular interaction of the secondary amine structure is weaker than that of the hydroxyl group. Therefore, among the -NH- groups contained in the fluorinated ether compound shown in Formula (1) on the protective layer, the interaction with the surface of the protective layer is preferred over the intramolecular interaction. As a result, the fluorinated ether compound shown in Formula (1) is less prone to aggregation on the protective layer compared to fluorinated ether compounds that have the same number of hydroxyl groups as the -NH- groups instead of the -NH- groups contained in the fluorinated ether compound shown in Formula (1), and can form a thin lubricating layer with sufficient coverage. Based on these factors, by using a lubricant containing the fluorinated ether compound shown in Formula (1), a lubricating layer with excellent wear resistance is obtained.

[0085] Furthermore, R in equation (1) 1 -R 2 -and-R 4 -R 5 At least one of them has more than one cyano group. Because the cyano group has a rigid C≡N bond and low degree of freedom, its intramolecular interaction is weaker than that of the hydroxyl group. Furthermore, because the cyano group has a nitrogen atom, it exhibits interaction with the protective layer. Therefore, among the cyano groups contained in the fluorinated ether compound of formula (1) on the protective layer, the interaction with the surface of the protective layer is preferred over intramolecular interaction. As a result, the fluorinated ether compound of formula (1) is less prone to aggregation on the protective layer compared to fluorinated ether compounds that have the same number of hydroxyl groups as the cyano groups instead of the cyano groups contained in the fluorinated ether compound of formula (1), and can form a thin lubricating layer with sufficient coverage.

[0086] Furthermore, the fluorinated ether compound shown in formula (1) contains one or more secondary amine structures and one or more cyano groups, thus achieving extremely strong adhesion properties to the protective layer through the synergistic effect of the secondary amine structure and the cyano group. Therefore, the fluorinated ether compound shown in formula (1) can form a lubricating layer with suppressed peeling, for example, compared with fluorinated ether compounds that do not contain either or both of the secondary amine structure and the cyano group.

[0087] Based on the above, when a lubricating layer is formed on the protective layer of the magnetic recording medium using a lubricant containing a fluorinated ether compound of this embodiment, excellent wear resistance and shedding resistance can be obtained even if the thickness is thin.

[0088] (R 2 R 4 )

[0089] R in equation (1) 2 and R 4Each is a divalent linker containing one or more heteroatoms and has one or more polar groups. R 2 and R 4 At least one of them contains one or more secondary amine structures (-NH-). Therefore, it becomes a fluorinated ether compound that can form a lubricating layer with excellent wear resistance.

[0090] As R 2 and R 4 The polar groups included can be hydroxyl, alkoxy, amide, amino, carbonyl, carboxyl, nitro, cyano, sulfonyl, and secondary amine structures. In R 2 and R 4 The polar groups in them do not contain ether bonds (-O-). Among them, R 2 and R 4 The polar group is preferably selected from secondary amine structures, hydroxyl groups, and cyano groups. This is because it is a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer.

[0091] R 2 and R 4 The number of polar groups contained is preferably 1 to 6, more preferably 1 to 4. Since R 2 and R 4 Each compound contains more than one polar group, thus exhibiting good adhesion to the protective layer and becoming a fluorinated ether compound capable of forming a lubricating layer with excellent wear resistance. If R 2 and R 4 If each contains 6 or fewer polar groups, it can prevent the fluorinated ether compounds from being too polar and thus adhering to the magnetic head as foreign matter (stains) during pickup.

[0092] R 2 and R 4 Each is preferably a linker with 1 to 15 carbon atoms, and more preferably a linker with 3 to 12 carbon atoms. Because if R 2 and R 4 When the number of carbon atoms is 1 to 15, the proportion of fluorine atoms in the molecule becomes appropriate, making it a fluorinated ether compound capable of forming a lubricating layer with excellent lubricity. However, in R... 2 and R 4 The carbon atom number of the linking group shown does not include the carbon atom number of the polar group mentioned above.

[0093] As R 2 and R 4 The heteroatoms included may include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, boron atoms, etc., and are preferably oxygen atoms and / or nitrogen atoms.

[0094] In R 2 In, with R1 The terminal part of the bonding side is a heteroatom. R 2 In R 1 The heteroatoms that are bonded are preferably oxygen or nitrogen atoms.

[0095] In R 4 In, with R 5 The terminal part of the bonding side is a heteroatom. R 4 In R 5 The heteroatoms that are bonded are preferably oxygen or nitrogen atoms.

[0096] In R 2 and / or R 4 When the main chain contains oxygen atoms as heteroatoms, it is preferable that the oxygen atoms form ether bonds (-O-). This is because it imparts a suitable degree of flexibility to the fluorinated ether compound and makes R... 2 and / or R 4 The polar groups of the connecting base shown have increased affinity with the protective layer, and can form a fluorinated ether compound that has better adhesion to the protective layer.

[0097] In R 2 and / or R 4 When the main chain contains nitrogen atoms as heteroatoms, it is preferable that the nitrogen atoms form a secondary amine structure (-NH-). This is because it becomes a fluorinated ether compound that can form a lubricating layer with excellent wear resistance.

[0098] R 2 and R 4 The linker shown is preferably a linker formed by combining groups selected from methylene (-CH2-), methylene substituted with hydroxyl or cyano (-CHY-; Y represents hydroxyl or cyano), -O-, and -NH- in any number and order to impart appropriate flexibility to the molecule as a whole.

[0099] -R in preferred formula (1) 2 -O- is represented by the following formula (2), -OR 4 - It is represented by the following formula (3).

[0100] -[A] a [B] d -O- (2)

[0101] -O-[C] g [D] j - (3)

[0102] (In equation (2), [A] is represented by equation (4-1) below, and [B] is represented by equation (4-2) below. In equation (2), the order of [A] and [B] can be interchanged. a is an integer from 0 to 3, d is an integer from 0 to 3, and at least one of a and d is 1 or higher. The end -CH2- on the opposite side of X in equation (4-1) or the end -CH2- on the opposite side of X in (4-2) combines with -O- in equation (2).)

[0103] (In equation (3), [C] is represented by equation (5-1) below, and [D] is represented by equation (5-2) below. The order of [C] and [D] in equation (3) can be interchanged. g is an integer from 0 to 3, j is an integer from 0 to 3, and at least one of g and j is 1 or higher. The end -CH2- on the opposite side of X in equation (5-1) or the end -CH2- on the opposite side of X in (5-2) combines with -O- in equation (3).)

[0104]

[0105] (In equation (4-1), b and c are integers from 0 to 4. In equation (4-2), e and f are integers from 0 to 4. In equation (5-1), h and i are integers from 0 to 4. In equation (5-2), k and l are integers from 0 to 4. In equations (4-1), (4-2), (5-1), and (5-2), X is 0 or NH. In equations (4-1), (4-2), (5-1), and (5-2), one or more of X are NH.)

[0106] In equation (2), [A] is represented by equation (4-1), and [B] is represented by equation (4-2). The terminal -CH2- on the opposite side of X in equation (4-1) or the terminal -CH2- on the opposite side of X in equation (4-2) combines with -O- in equation (2). In equation (2), a is an integer from 0 to 3, d is an integer from 0 to 3, and at least one of a and d is 1 or more. That is, equation (2) contains at least one of [A] and [B].

[0107] In equation (2), the order of [A] and [B] can be interchanged. There are no special restrictions on the order of [A] and [B] in equation (2) when a is 2 or more and d is 1 or more, or when d is 2 or more and a is 1 or more.

[0108] In formula (2), since at least one of a and d is 1 or more, it becomes a fluorinated ether compound that can form a lubricating layer with good adhesion to the protective layer. The sum of a and d in formula (2) is 6 or less, preferably 4 or less, and more preferably 2 or less. If the sum of a and d in formula (2) is 6 or less, it is preferable to prevent the fluorinated ether compound from being picked up as a foreign object (stain) due to excessively high polarity.

[0109] When a in equation (2) is 2 or more, the repeating units (-X-CH2-(CH2)) shown in equation (4-1) c -CH(OH)-(CH2) b In -CH2-), the combination of b and c can be the same or different.

[0110] When d in equation (2) is 2 or more, the repeating units (-X-CH2-(CH2)) shown in equation (4-2) f -CH(CN)-(CH2) e In -CH2-), the combination of e and f can be the same or different.

[0111] In equation (4-1), b and c, and in equation (4-2), e and f, are each integers from 0 to 4, preferably integers from 0 to 3. Furthermore, the sum of b and c in equation (4-1) and the sum of e and f in equation (4-2) are each preferably from 0 to 4. If the sum of b and c in equation (4-1) and the sum of e and f in equation (4-2) are each from 0 to 4, then the polar bases in equations (4-1) and (4-2) and R... 1 It is preferred that the distance between the polar groups and / or the distance between each other in equations (4-1) and (4-2) becomes appropriate.

[0112] In the fluorinated ether compound of this embodiment, -R in formula (1) 2 -O- can be appropriately selected based on the required performance of lubricants containing fluorinated ether compounds.

[0113] -R in equation (1) 2 -O-(as shown in equation (2) -[A) a -[B] d -O-) is preferably any of the following formulas (11-1) to (11-12). If -R in formula (1) 2 If -O- is any of the compounds shown in formulas (11-1) to (11-12), then it becomes a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer. For the structures shown in formulas (11-1) to (11-12), R 1 With R 2 The one in is configured on the far left (far R).1 It combines with heteroatoms (oxygen or nitrogen atoms) on the side.

[0114]

[0115]

[0116] In equation (3), [C] is represented by equation (5-1), and [D] is represented by equation (5-2). The terminal -CH2- on the opposite side of X in equation (5-1) or the terminal -CH2- on the opposite side of X in equation (5-2) combines with -O- in equation (3). In equation (3), g is an integer from 0 to 3, j is an integer from 0 to 3, and at least one of g and j is 1 or more. That is, equation (3) contains at least one of [C] and [D].

[0117] In equation (3), the order of [C] and [D] can be interchanged. In equation (3), when g is 2 or more and j is 1 or more, or when j is 2 or more and g is 1 or more, there is no particular restriction on the order of [C] and [D] in equation (3).

[0118] In formula (3), since at least one of g and j is 1 or more, it becomes a fluorinated ether compound that can form a lubricating layer with good adhesion to the protective layer. The sum of g and j in formula (3) is 6 or less, preferably 4 or less, and more preferably 2 or less. If the sum of g and j in formula (3) is 6 or less, it is preferable to prevent the fluorinated ether compound from being picked up as foreign matter (stains) due to excessively high polarity.

[0119] When g in equation (3) is 2 or more, the repeating units (-CH2-(CH2)) shown in equation (5-1) h -CH(OH)-(CH2) i In -CH2-X-), the combination of h and i can be the same or different.

[0120] When j in equation (3) is 2 or more, the repeating units (-CH2-(CH2)) shown in equation (5-2) k -CH(CN)-(CH2) l In -CH2-X-), the combination of k and l can be the same or different.

[0121] In equation (5-1), h and i, and in equation (5-2), k and l, are each integers from 0 to 4, preferably integers from 0 to 3. Furthermore, the sum of h and i in equation (5-1) and the sum of k and l in equation (5-2) are each preferably from 0 to 4. If the sum of h and i in equation (5-1) and the sum of k and l in equation (5-2) are each from 0 to 4, then the polar bases in equations (5-1) and (5-2) and R... 5 It is preferred that the distance between the polar groups in equations (5-1) and (5-2) and / or the distance between the polar groups in equations (5-2) becomes appropriate.

[0122] In the fluorinated ether compound of this embodiment, -OR in formula (1) 4 - The appropriate choice can be made based on the required performance of the lubricant containing fluorinated ether compounds.

[0123] -OR in equation (1) 4 -(as shown in equation (3) -O-[C]) g -[D] j -) is preferably any of the following formulas (12-1) to (12-12). If -OR in formula (1) 4 - If any of the compounds shown in formulas (12-1) to (12-12) are used, then the compound becomes a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer. For the structures shown in formulas (12-1) to (12-12), R 5 With R 4 The one in is configured on the far right (the far R). 5 It combines with heteroatoms (oxygen or nitrogen atoms) on the side.

[0124]

[0125]

[0126]

[0127]

[0128] (R 1 R 5 )

[0129] In the fluorinated ether compound of this embodiment shown in formula (1) above, R 1 To be with R 2 The terminal group of the bond, R 5 To be with R 4 The terminal group of the bond. R 1 and R 5 Each can be independently an alkyl group that may have substituents, or a hydrocarbon group that has a double or triple bond. In R1 and R 5 In the middle, each with R 2 R 4 The last part of the bond side is a carbon atom.

[0130] In the fluorinated ether compound shown in formula (1), in R 2 and R 4 In the case that none of the linking groups shown contain cyano groups, R 1 and R 5 At least one of them has a cyano group as a substituent.

[0131] As R 1 and / or R 5 The alkyl group can be a substituent alkyl group, preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms. Specifically, examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl, which can be straight-chain or branched.

[0132] Examples of substituents in alkyl groups that can have substituents include halogenated groups, alkoxy groups, hydroxyl groups, cyano groups, etc., with hydroxyl or cyano groups being preferred. When the alkyl group that can have substituents has these substituents, it becomes a fluorinated ether compound that can form a lubricating layer with superior wear resistance.

[0133] In this embodiment, R is preferred in order to form a fluorinated ether compound that can create a lubricating layer with superior wear resistance. 1 and R 5 At least one of them is an alkyl group having a cyano group.

[0134] The alkyl group having a halogenated group as a substituent is preferably an alkyl group having at least one fluorine group. Examples of alkyl groups having a fluorine group include trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, octafluoropentyl, tridecafluorooctyl, etc.

[0135] As an alkyl group having a hydroxyl group as a substituent, it is preferably an alkyl group having 1 to 6 carbon atoms having a hydroxyl group, and more preferably an alkyl group shown in the following formula (13-1).

[0136]

[0137] (In equation (13-1), R) 6 (This refers to an alkyl group or hydrogen atom with 1 to 4 carbon atoms, where p represents an integer from 1 to 6.)

[0138] In equation (13-1), R 6It is an alkyl group or a hydrogen atom having 1 to 4 carbon atoms, preferably a hydrogen atom. In the structure shown in formula (13-1), the left side is connected to R. 2 Or R 4 Combined. In formula (13-1), p represents an integer from 1 to 6, preferably an integer from 1 to 4, more preferably 2 or 3. When p is 2 or more, the repeating unit (-CH(R) 6 R in )-) 6 They can be different, or partially or entirely the same. If the number of carbon atoms (R) in equation (13-1) 6 If the total number of carbon atoms and p is 1 to 6, then the decrease in the overall surface free energy of the molecule due to the low proportion of fluorine atoms in the fluorinated ether compound molecule will not occur, which is preferred.

[0139] The alkyl group having a cyano group as a substituent is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group represented by the following formula (13-2).

[0140]

[0141] (In equation (13-2), R) 6 (This refers to an alkyl group or hydrogen atom with 1 to 4 carbon atoms, where q represents an integer from 1 to 6.)

[0142] In equation (13-2), R 6 It is an alkyl group or a hydrogen atom having 1 to 4 carbon atoms, preferably a hydrogen atom. In the structure shown in formula (13-2), the left side is connected to R. 2 Or R 4 Combined. In equation (13-2), q represents an integer from 1 to 6, preferably an integer from 1 to 4, more preferably 2 or 3. When q is 2 or more, the repeating unit (-CH(R) 6 R in )-) 6 They can be different, or partially or entirely the same. If the number of carbon atoms (R) in equation (13-2) 6 If the sum of the number of carbon atoms contained in the compound and q is 1 to 6, then the overall surface free energy of the molecule will not decrease due to the low proportion of fluorine atoms in the fluorinated ether compound molecule, which is preferred.

[0143] Alkyl groups having cyano groups as substituents can have two or more cyano groups. Examples of alkyl groups having two cyano groups include 5-cyano-3-(cyanomethyl)pentyl, 4-cyano-1-(cyanomethyl)butyl, 4-cyano-2-(cyanomethyl)butyl, 4-cyano-3-(cyanomethyl)butyl, 4-cyano-1-(cyanoethyl)butyl, 4-cyano-2-(cyanoethyl)butyl, 3-cyano-1-(cyanomethyl)propyl, 3-cyano-2-(cyanomethyl)propyl, 3-cyano-1-(cyanoethyl)propyl, and 2-cyano-1-(cyanomethyl)ethyl.

[0144] As R 1 and / or R 5 The hydrocarbon group having a double or triple bond is a hydrocarbon group having at least one double or triple bond. The double bond can be either an alkene double bond or an aromatic double bond. Examples of hydrocarbon groups having double or triple bonds include groups containing aromatic hydrocarbons, groups containing aromatic heterocycles, alkenyl groups, alkynyl groups, etc. Hydrocarbon groups having double or triple bonds can have substituents such as alkyl, alkoxy, hydroxyl, mercapto, carboxyl, carbonyl, amino, cyano, halogenated, etc. Specifically, hydrocarbon groups having double or triple bonds can be phenyl, methoxyphenyl, fluorophenyl, naphthyl, phenethyl, methoxyphenethyl, fluorophenethyl, benzyl, methoxybenzyl, naphthylmethyl, methoxynaphthyl, pyrrole, pyrazolyl, methylpyrazolylmethyl, imidazolyl, furanyl, furfural, etc. azole group, iso Azolyl, thiophene, thiopheneylethyl, thiazolyl, methylthiazolylethyl, isothiazolyl, pyridyl, pyrimidinyl, pyrazinyl, dihydroindolyl, benzofuranyl, benzothiophene, benzimidazolyl, benzo[] Azolyl, benzothiazolyl, benzopyrazole, benzisocyanate Azolyl, benzisothiazolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, phthalazinyl, cyclolinyl, vinyl, allyl, butenyl, 1-propynyl, propynyl (2-propynyl), butynyl, methylbutynyl, penynyl, methylpentynyl, hexynyl.

[0145] The hydrocarbon group having double or triple bonds is preferably any one of phenyl, methoxyphenyl, thienylethyl, butenyl, allyl, propargyl, phenethyl, methoxyphenethyl, or fluorophenylethyl, and more preferably phenyl, thienylethyl, allyl, or butenyl. When the hydrocarbon group having double or triple bonds is any one of phenyl, thienylethyl, allyl, or butenyl, it becomes a fluorinated ether compound capable of forming a lubricating layer with superior wear resistance.

[0146] (R 3 )

[0147] In the fluorinated ether compound of this embodiment shown in formula (1) above, R 3 It is a perfluoropolyether chain (PFPE chain). R 3 There are no particular limitations; the appropriate choice can be made based on the required performance of the lubricant containing fluorinated ether compounds. Examples of PFPE chains include those formed from polymers of perfluoromethylene oxide, perfluoroethyl oxide, perfluoropropylene oxide, perfluoroisopropylene oxide, and copolymers thereof.

[0148] The PFPE chain can be, for example, a structure represented by the following formula (Rf) of a polymer or copolymer derived from a perfluoroalkylene oxide.

[0149] -(CF2) p1 O(CF2O) p2 (CF2CF2O) p3 (CF2CF2CF2O) p4 (CF2CF2CF2CF2O) p5 (CF2) p6 -(Rf)

[0150] (In equation (Rf), p2, p3, p4, and p5 represent the average degree of polymerization, each independently representing 0 to 30; p2, p3, p4, and p5 will not all be 0 at the same time; p1 and p6 represent the average number of -CF2-, each independently representing 1 to 3; there is no particular restriction on the order of repeating units in equation (Rf).)

[0151] In formula (Rf), p2, p3, p4, and p5 represent the average degree of polymerization, each independently representing 0 to 30, preferably 0 to 20, and more preferably 0 to 15.

[0152] In formula (Rf), p1 and p6 are average values ​​representing the number of -CF2-, each independently representing 1 to 3. In the polymer shown in formula (Rf), p1 and p6 are determined based on the structure of the repeating units arranged at the ends of the chain structure.

[0153] In equation (Rf), (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) are repeating units. There are no particular restrictions on the order of the repeating units in equation (Rf). Furthermore, there are no particular restrictions on the number of different types of repeating units in equation (Rf).

[0154] R in equation (1) 3For example, a PFPE chain as shown in the following formula (Rf-1) is preferred.

[0155] -(CF2) p7 O-(CF2CF2O) p8 -(CF2CF2CF2O) p9 -(CF2) p10 -(Rf-1)

[0156] (In equation (Rf-1), p8 and p9 represent the average degree of polymerization, each independently representing 0.1 to 30; p7 and p10 represent the average number of -CF2-, each independently representing 1 to 2.)

[0157] There is no particular restriction on the order of (CF2CF2O) and (CF2CF2CF2O) as repeating units in formula (Rf-1). Formula (Rf-1) may include any of the random copolymers, block copolymers, and alternating copolymers formed from monomer units (CF2CF2O) and (CF2CF2CF2O). In formula (Rf-1), p8 and p9, which represent the average degree of polymerization, are each independently represented as 0.1 to 30, preferably 0.1 to 20, and more preferably 1 to 15. p7 and p10 in formula (Rf-1) are average values ​​representing the number of -CF2-, and are each independently represented as 1 to 2. p7 and p10 in the polymer shown in formula (Rf-1) are determined according to the structure of the repeating units arranged at the ends of the chain structure.

[0158] R in equation (1) 3 It is also preferred to use any of the following formulas (6) to (10). In addition, there is no particular restriction on the order of (CF2CF2O) and (CF2O) as repeating units in formula (6). Formula (6) may include any of the random copolymers, block copolymers and alternating copolymers formed by monomer units (CF2-CF2-O) and (CF2-O).

[0159] -CF₂O-(CF₂CF₂O) m -(CF2O) n -CF2- (6)

[0160] (In equation (6), m and n represent the average degree of polymerization, each ranging from 0.1 to 30.)

[0161] -CF₂O-(CF₂CF₂O) w -CF2- (7)

[0162] (In equation (7), w represents the average degree of polymerization, ranging from 0.1 to 30.)

[0163] -CF2CF2O-(CF2CF2CF2O) x -CF2CF2- (8)

[0164] (x in equation (8) represents the average degree of polymerization, ranging from 0.1 to 30.)

[0165] -CF2CF2CF2O-(CF2CF2CF2CF2O) y -CF2CF2CF2- (9)

[0166] (In equation (9), y represents the average degree of polymerization, ranging from 0.1 to 30.)

[0167] -CF(CF3)-(OCF(CF3)CF2) z -OCF(CF3)- (10)

[0168] (In equation (10), z represents the average degree of polymerization, ranging from 0.1 to 30.)

[0169] When m, n, w, x, y, and z in formulas (6) to (10) are each 0.1 to 30, the lubricant containing them is easy to apply, and a lubricating layer with good adhesion can be obtained. The amounts of m, n, w, x, y, and z in formulas (6) to (10) are preferably 20 or less, more preferably 15 or less, and can be 10 or less. The amounts of m, n, w, x, y, and z in formulas (6) to (10) are preferably 1 or more, more preferably 2 or more, can be 3 or more, and can be 5 or more.

[0170] In equation (1) R 3 In the case of any of formulas (6) to (10), the synthesis of fluorinated ether compounds is easy and preferred. In R 3 In the case of formula (6), the raw materials are readily available, and therefore it is a better option.

[0171] Furthermore, in R 3 In the case of any of formulas (6) to (10), the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) to the number of carbon atoms in the perfluoropolyether chain is appropriate. Therefore, a fluorinated ether compound with moderate hardness is obtained. Consequently, the fluorinated ether compound coated on the protective layer does not easily agglomerate on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage. Furthermore, in R... 3 In the case of any one of formulas (6) to (10), it becomes a fluorinated ether compound that can obtain a lubricating layer with good wear resistance.

[0172] The R of the fluorinated ether compound of this embodiment shown in formula (1) above 1 -R 2 -and-R4 -R 5 At least one of them has one or more cyano groups. That is, in the fluorinated ether compounds shown in formula (1), the group selected from R 1 R 2 R 4 R 5 At least one of them has one or more cyano groups. The fluorinated ether compound of this embodiment, due to R... 1 -R 2 -and-R 4 -R 5 At least one of them has more than one cyano group, thus it can form a lubricating layer with good adhesion to the protective layer.

[0173] In the fluorinated ether compound shown in formula (1), the molecule may contain two or more cyano groups. When the number of cyano groups in the molecule is two or more, it is preferable that R... 1 -R 2 -and-R 4 -R 5 Each contains one or more cyano groups. If in R... 1 -R 2 -and-R 4 -R 5 If each component contains one or more cyano groups, the adhesion between the lubricating layer and the protective layer becomes better in a lubricating layer containing a fluorinated ether compound.

[0174] In the fluorinated ether compound shown in formula (1), it is preferable that the number of cyano groups contained in the molecule is 3 or less, more preferably 2 or less. If the total number of cyano groups contained in the molecule is 3 or less, it is preferable that the fluorinated ether compound is too polar and will adhere to the magnetic head as a foreign object (stain) during pickup.

[0175] In the fluorinated ether compound shown in formula (1), R 2 and R 4 At least one of them contains one or more secondary amine structures (-NH-). For the fluorinated ether compound shown in formula (1), a lubricating layer with better adhesion to the protective layer can be obtained, therefore the number of secondary amine structures contained in the molecule is preferably 2 or more. When the number of secondary amine structures contained in the molecule is 2 or more, it is preferable that R 2 and R 4 Each contains one or more secondary amine structures. If in R... 2 and R 4 If each component contains one or more secondary amine structures, the adhesion between the lubricating layer and the protective layer becomes better in a lubricating layer containing fluorinated ether compounds.

[0176] In the fluorinated ether compound shown in formula (1), it is preferable that the number of secondary amine structures contained in the molecule is 6 or less, more preferably 4 or less. If the number of secondary amine structures contained in the molecule is 6 or less, it is preferable that the fluorinated ether compound is too polar and will adhere to the magnetic head as a foreign object (stain) during pickup.

[0177] In the fluorinated ether compound of this embodiment, it is preferable that the number of hydroxyl groups contained in the molecule is 1 or more, and can be 2 or more. If hydroxyl groups are included in the molecule, it becomes a fluorinated ether compound that provides a lubricating layer with better adhesion to the protective layer. When the number of hydroxyl groups contained in the molecule is 2 or more, it is more preferable that the R... 1 -R 2 -and-R 4 -R 5 Each contains more than one hydroxyl group. If in R 1 -R 2 -and-R 4 -R 5 If each component contains one or more hydroxyl groups, the adhesion between the lubricating layer and the protective layer becomes better in a lubricating layer containing a fluorinated ether compound.

[0178] In the fluorinated ether compound shown in formula (1), it is preferable that the number of hydroxyl groups contained in the molecule is 3 or less, more preferably 2 or less. If the total number of hydroxyl groups contained in the molecule is 3 or less, the aggregation of the fluorinated ether compound on the protective layer caused by the intramolecular interaction of the hydroxyl groups is less likely to occur. Therefore, a thin lubricating layer can be formed with a better coverage ratio, and better wear resistance can be obtained.

[0179] For the fluorinated ether compound shown in formula (1), it is preferable that the total number of hydroxyl groups, secondary amine structures (-NH-), and cyano groups contained in the molecule is 8 or less, more preferably 6 or less. In this case, excessive polarity of the fluorinated ether compound can be prevented from causing pick-up.

[0180] The fluorinated ether compound shown in formula (1) preferably contains 2 or more secondary amine structures, 3 or fewer hydroxyl groups, and 3 or fewer cyano groups, and the total number of secondary amine structures, hydroxyl groups, and cyano groups is 8 or fewer. In this case, aggregation of the fluorinated ether compound on the protective layer caused by intramolecular interactions of hydroxyl groups is less likely to occur, and a high synergistic effect of interaction with the protective layer caused by the inclusion of secondary amine structures and cyano groups can be obtained. As a result, a fluorinated ether compound with superior wear resistance and detachment resistance can be obtained.

[0181] In the fluorinated ether compound shown in formula (1), R 1 With R 5 They can be the same or different. If R 1 With R 5If the same compound is present, it readily and uniformly wets and spreads on the protective layer, resulting in a lubricating layer with a uniform film thickness. Consequently, the lubricating layer containing this fluorinated ether compound tends to have good coverage and achieves superior wear resistance. Furthermore, if R... 1 With R 5 If the same conditions are met, fluorinated ether compounds can sometimes be easily manufactured.

[0182] Furthermore, in the fluorinated ether compound shown in formula (1), R 2 With R 4 They can be the same or different. If R 2 With R 4 If the same, it easily and uniformly wets and spreads on the protective layer, becoming a fluorinated ether compound that easily produces a lubricating layer with a uniform film thickness. If R 2 With R 4 If the same conditions are met, fluorinated ether compounds can sometimes be easily manufactured.

[0183] Furthermore, if the R of the fluorinated ether compound shown in formula (1) 1 With R 5 Same, and R 2 With R 4 If they are the same, they can be easily manufactured. Furthermore, if R... 1 With R 5 Same, and R 2 With R 4 If the same, it is easier to wet and spread evenly on the protective layer, becoming a fluorinated ether compound that is easier to obtain a lubricating layer with a more uniform film thickness.

[0184] Specifically, the fluorinated ether compound represented by formula (1) is preferably any of the compounds shown in formulas (A) to (Z) below. In addition, the average degree of polymerization (repetition number) ma~mv, na~nv, w, x, y, z in formulas (A) to (Z) are not necessarily integers since they are values ​​showing average values.

[0185] The compound shown in formula (A) has R in formula (1). 1 It is 3-cyanopropyl, R 2 With [A], R 3 For formula (6). The R of the compound shown in formula (A) 1 With R 5 Same, R 2 With R 4 same.

[0186] The compound shown in formula (B) has R in formula (1). 1 It is 4-cyanobutyl, R 2 With [A], R 3For formula (6). The R of the compound shown in formula (B) 1 With R 5 Same, R 2 With R 4 same.

[0187] The compound shown in formula (C) has R in formula (1). 1 It is 2-cyanopropyl, R 2 With [A], R 3 For formula (6). The R of the compound shown in formula (C) 1 With R 5 Same, R 2 With R 4 same.

[0188] The compound shown in formula (D) has R in formula (1). 1 It is 3-cyanopropyl, R 2 It has 2 [A], R 3 For formula (6). The R of the compound shown in formula (D) 1 With R 5 Same, R 2 With R 4 same.

[0189] The compound shown in formula (E) has R in formula (1). 1 It is 3-cyanopropyl, R 2 It has 2 [A], R 3 For formula (6). The R of the compound shown in formula (E) 1 With R 5 Same, R 2 With R 4 same.

[0190] The compound shown in formula (F) has R in formula (1). 1 It is 3-cyanopropyl, R 2 Having [A] and [B], R 3 For formula (6). The R of the compound shown in formula (F) 1 With R 5 Same, R 2 With R 4 same.

[0191] The compound represented by formula (G) has R in formula (1). 1 It is 3-hydroxypropyl, R 2 Having [A] and [B], R 3 For formula (6). The R of the compound shown in formula (G) 1 With R 5 Same, R 2 With R 4 same.

[0192] The compound represented by formula (H) in formula (1) has R 1 It is 2-hydroxyethyl, R 2 With [A], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0193] The compound shown in formula (I) has R in formula (1). 1 It is 3-hydroxypropyl, R 2 It has 2 [A], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0194] The compound represented by formula (J) has R in formula (1). 1 It is 3-cyanopropyl, R 2 With [A], R 3 Equation (6). R 4 With [C], R 5 With R 1 same.

[0195] The compound represented by formula (K) in formula (1) has R 1 It is 4-hydroxybutyl, R 2 Having [A] and [B], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0196] The compound represented by formula (L) has R in formula (1). 1 It is 3-cyanopropyl, R 2 Having [A] and [B], R 3 Equation (6). R 4 With [C], R 5 With R 1 same.

[0197] The compound represented by formula (M) in formula (1) has R 1 It is 2-propynyl, R 2 With [A], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0198] The R of the compound represented by formula (N) 1 For propyl, R 2 With [A], R 3Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0199] The compound represented by formula (O) has R in formula (1). 1 It is 4-methoxyphenyl, R 2 With [A], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0200] The compound represented by formula (P) has R in formula (1). 1 It is allyl, R 2 It has 2 [A], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0201] The compound represented by formula (Q) has R in formula (1). 1 It is 3-butenyl, R 2 Having [A] and [B], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0202] The compound represented by formula (R) is in formula (1), where R 1 It is 3-cyanopropyl, R 2 It has 3 [A], R 3 Equation (6). R 4 With [C], R 5 With R 1 same.

[0203] The compound represented by formula (S) has R in formula (1). 1 It is 2-hydroxyethyl, R 2 With 1 [A] and 2 [B], R 3 Equation (6). R 4 With [C], R 5 It is 3-cyanopropyl.

[0204] The compound represented by formula (T) has R in formula (1). 1 It is 3-cyanopropyl, R 2 With 2 [A] and 1 [B], R 3 Equation (6). R 4 With [C], R 5 With R 1 same.

[0205] The compound represented by formula (U) has R in formula (1). 1 It is allyl, R 2 With [A], R 3 Equation (6). R 4 With [C], R 5 It is 4-cyano-2-(cyanomethyl)butyl.

[0206] The compound represented by formula (V) has R in formula (1). 1 It is allyl, R 2 It has 3 [A], R 3 Equation (6). R 4 With [C], R 5 It is 4-cyano-2-(cyanomethyl)butyl.

[0207] The compound represented by formula (W) has R in formula (1). 1 It is allyl, R 2 It has 2 [A], R 3 For equation (7). R 4 With [C], R 5 It is 3-cyanopropyl.

[0208] The compound represented by formula (X) has R in formula (1). 1 It is allyl, R 2 It has 2 [A], R 3 Equation (8). R 4 With [C], R 5 It is 3-cyanopropyl.

[0209] The compound represented by formula (Y) has R in formula (1). 1 It is allyl, R 2 It has 2 [A], R 3 Equation (9). R 4 With [C], R 5 It is 3-cyanopropyl.

[0210] The compound represented by formula (Z) has R in formula (1). 1 It is allyl, R 2 It has 2 [A], R 3 Equation (10). R 4 With [C], R 5 It is 3-cyanopropyl.

[0211] The following shows compounds represented by formulas (A) to (Z).

[0212]

[0213] (In formula (A), ma and na represent the average degree of polymerization, where ma represents 1 to 30 and na represents 0.1 to 30.)

[0214] (In equation (B), mb and nb represent the average degree of polymerization, where mb represents 1 to 30 and nb represents 0.1 to 30.)

[0215] (In equation (C), mc and nc represent the average degree of polymerization, where mc represents 1 to 30 and nc represents 0.1 to 30.)

[0216]

[0217] (In equation (D), md and nd represent the average degree of polymerization, where md represents 1 to 30 and nd represents 0.1 to 30.)

[0218] (In equation (E), me and ne represent the average degree of polymerization, where me represents 1 to 30 and ne represents 0.1 to 30.)

[0219] (In formula (F), mf and nf represent the average degree of polymerization, where mf represents 1 to 30 and nf represents 0.1 to 30.)

[0220] (In formula (G), mg and ng represent the average degree of polymerization, with mg representing 1 to 30 and ng representing 0.1 to 30.)

[0221]

[0222] (In formula (H), mh and nh represent the average degree of polymerization, where mh represents 1 to 30 and nh represents 0.1 to 30.)

[0223] (In equation (I), mi and ni represent the average degree of polymerization, where mi represents 1 to 30 and ni represents 0.1 to 30.)

[0224]

[0225] (In formula (J), mj and nj represent the average degree of polymerization, where mj represents 1 to 30 and nj represents 0.1 to 30.)

[0226] (In formula (K), mk and nk represent the average degree of polymerization, where mk represents 1 to 30 and nk represents 0.1 to 30.)

[0227] (In formula (L), ml and nl represent the average degree of polymerization, where ml represents 1 to 30 and nl represents 0.1 to 30.)

[0228]

[0229] (In formula (M), mm and nm represent the average degree of polymerization, with mm representing 1 to 30 and nm representing 0.1 to 30.)

[0230] (In equation (N), mn and nn represent the average degree of polymerization, where mn represents 1 to 30 and nn represents 0.1 to 30.)

[0231]

[0232] (In formula (O), mo and no represent the average degree of polymerization, where mo represents 1 to 30 and no represents 0.1 to 30.)

[0233] (In formula (P), mp and np represent the average degree of polymerization, where mp represents 1 to 30 and np represents 0.1 to 30.)

[0234] (In equation (Q), mq and nq represent the average degree of polymerization, where mq represents 1 to 30 and nq represents 0.1 to 30.)

[0235]

[0236] (In equation (R), mr and nr represent the average degree of polymerization, where mr represents 1 to 30 and nr represents 0.1 to 30.)

[0237] (In formula (S), ms and ns represent the average degree of polymerization, where ms represents 1 to 30 and ns represents 0.1 to 30.)

[0238] (In formula (T), mt and nt represent the average degree of polymerization, where mt represents 1 to 30 and nt represents 0.1 to 30.)

[0239]

[0240] (In formula (U), mu and nu represent the average degree of polymerization, where mu represents 1 to 30 and nu represents 0.1 to 30.)

[0241] (In formula (V), mv and nv represent the average degree of polymerization, where mv represents 1 to 30 and nv represents 0.1 to 30.)

[0242]

[0243] (In formula (W), w represents the average degree of polymerization, and w ranges from 0.1 to 30.)

[0244] (In equation (X), x represents the average degree of polymerization, and x ranges from 0.1 to 30.)

[0245]

[0246] (In formula (Y), y represents the average degree of polymerization, and y represents 0.1 to 30.)

[0247] (In formula (Z), z represents the average degree of polymerization, and z represents 0.1 to 30.)

[0248] If the compound represented by formula (1) is any of the compounds represented by formulas (A) to (Z) above, the raw materials are readily available, and a lubricating layer with excellent wear resistance and detachment resistance can be formed even with a thin thickness, which is preferred. Among them, any of the compounds represented by formulas (A) to (C), (J) to (Q), (U), and (W) to (Z) is more preferred in order to form a lubricating layer with even better wear resistance. In particular, any of the compounds represented by formulas (A), (J), (P), (Q), and (U) are preferred. This is because, through the secondary amine structure in R 2 and R 4 The numbers are appropriate and are placed in the appropriate positions in R. 1 -R 2 -and-R 4 -R 5 In at least one of them, the cyano groups are in an appropriate number and are arranged in an appropriate position, thereby improving the adhesion between the lubricating layer and the protective layer.

[0249] The fluorinated ether compound in this embodiment preferably has a number-average molecular weight (Mn) in the range of 500 to 10,000. If the number-average molecular weight is 500 or higher, the lubricant containing the fluorinated ether compound of this embodiment is less prone to evaporation, and a lubricating layer that is less likely to experience film thickness reduction due to peeling can be formed. Furthermore, if the number-average molecular weight is 500 or higher, lubricant evaporation and migration to the magnetic head can be prevented. The number-average molecular weight of the fluorinated ether compound is more preferably 1,000 or higher. Furthermore, if the number-average molecular weight is 10,000 or lower, the viscosity of the fluorinated ether compound becomes suitable, and a thin lubricating layer can be easily formed by coating the lubricant containing it. To achieve a viscosity that is easy to handle when applied as a lubricant, the number-average molecular weight of the fluorinated ether compound is more preferably 3,000 or lower.

[0250] The number-average molecular weight (Mn) of the fluorinated ether compounds was determined by using AVANCE III 400 manufactured by Blu-ray Bio-Spin Corporation. 1 H-NMR and 19 The value is obtained by F-NMR. In NMR (nuclear magnetic resonance) determination, the sample is diluted in one or a mixture of solvents such as hexafluorobenzene, d-acetone, and d-tetrahydrofuran for determination. 19 The baseline for F-NMR chemical shift is set at -164.7 ppm for the peak of hexafluorobenzene. 1The baseline for H-NMR chemical shift is set at 2.2 ppm for the acetone peak.

[0251] "Manufacturing method"

[0252] The method for manufacturing the fluorinated ether compound of this embodiment is not particularly limited, and conventionally known manufacturing methods can be used. For example, the fluorinated ether compound of this embodiment can be manufactured using the manufacturing method shown below.

[0253] First, prepare R in equation (1) 3 The two ends of the corresponding perfluoropolyether chain are respectively configured with fluorinated compounds containing hydroxymethyl (-CH2OH).

[0254] Next, the hydroxyl group of the hydroxymethyl group at one end of the above-mentioned fluorinated compound is replaced with R from formula (1). 1 -R 2 - The group constitutes (reaction 1). Then, the hydroxyl group of the hydroxymethyl group configured at another end is replaced by -R in formula (1). 4 -R 5 The terminal group formed (reaction 2).

[0255] The first and second reactions can be carried out using conventionally known methods, based on R in equation (1). 1 R 2 R 4 R 5 The type, etc., can be appropriately determined. Furthermore, either reaction 1 or reaction 2 can be performed first. In R... 1 R 5 Same, and R 2 R 4 Under the same conditions, the first reaction and the second reaction can occur simultaneously.

[0256] The compound shown in formula (1) can be obtained by the above method.

[0257] In this embodiment, in order to manufacture -R 2 -O- is represented by equation (2), -OR 4 - The fluorinated ether compound represented by formula (3) is preferably an epoxide compound. This epoxide compound can be commercially available or synthesized. In the case of synthesizing the epoxide compound, for example, it can be synthesized using the following (a) and (b). The epoxide compound can be synthesized by oxidizing unsaturated bonds.

[0258] (a) Having the same R as the manufactured fluorinated ether compound 1 Or R 5 The terminal groups shown correspond to the structures of alcohols or protected amines.

[0259] (b) Selected from epichlorohydrin, epibromohydrin, and 2-bromoethyl ethylene oxide.

[0260] The fluorinated ether compound in this embodiment is the compound shown in formula (1) above. Therefore, if a lubricating layer is formed on the protective layer using a lubricant containing it, then by using R in formula (1) 3 The PFPE chain shown is covered with a protective layer on its surface, and the friction between the magnetic head and the protective layer is reduced.

[0261] Furthermore, in the lubricating layer formed using a lubricant containing a fluorinated ether compound of this embodiment, R in formula (1) 1 and R 5 The terminal base shown, and R 2 and R 4 At least one of them contains a secondary amine structure (-NH-), and R 1 -R 2 -and-R 4 -R 5 The aggregation of fluorinated ether compounds on the protective layer is less likely to occur due to intramolecular interactions between the cyano groups contained in at least one of them. Furthermore, a high level of interaction with the protective layer can be achieved through the synergistic effect of the inclusion of the secondary amine structure and the cyano group. Based on these factors, the fluorinated ether compound according to this embodiment can form a lubricating layer with excellent wear resistance and detachment resistance.

[0262] Lubricant for magnetic recording media

[0263] The lubricant for the magnetic recording medium in this embodiment comprises a fluorinated ether compound as shown in formula (1).

[0264] In this embodiment, the lubricant can be a mixture of known materials used as lubricants, provided that the properties of the fluorinated ether compound represented by formula (1) are not impaired.

[0265] Specific examples of known materials include, for instance, FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (and above, manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco). The known materials used in combination with the lubricant of this embodiment preferably have a number-average molecular weight of 1000 to 10000.

[0266] When the lubricant of this embodiment contains materials other than the fluorinated ether compound shown in formula (1), the content of the fluorinated ether compound shown in formula (1) in the lubricant of this embodiment is preferably 50% by mass or more, more preferably 70% by mass or more. The upper limit can be arbitrarily selected, but for example, it can be 99% by mass or less, 95% by mass or less, 90% by mass or less, or 85% by mass or less.

[0267] The lubricant of this embodiment contains a fluorinated ether compound as shown in formula (1), thus enabling the formation of a lubricating layer that can cover the surface of the protective layer with a high coverage rate even when the thickness is thin, and exhibits excellent adhesion to the protective layer. Therefore, the lubricant according to this embodiment can form a lubricating layer that has excellent wear resistance even when the thickness is thin, and where film thickness reduction due to peeling is not likely to occur.

[0268] Furthermore, since the lubricant of this embodiment contains a fluorinated ether compound as shown in formula (1), the fluorinated ether compound in the lubricating layer, which does not adhere (adsorb) to the protective layer, is less likely to agglomerate. Therefore, it is possible to prevent the fluorinated ether compound from agglomerating and adhering to the magnetic head as foreign matter (stains), thus inhibiting pickup.

[0269] Furthermore, the lubricant of this embodiment contains a fluorinated ether compound as shown in formula (1), therefore, through R in formula (1) 1 and R 5 The terminal base shown, R 2 and R 4 At least one of them contains a secondary amine structure (-NH-), R 1 -R 2 -and-R 4 -R 5 The cyano group contained in at least one of the components interacts with the protective layer to form a lubricating layer with excellent wear resistance and shedding resistance.

[0270] [Magnetic recording media]

[0271] In this embodiment, the magnetic recording medium has at least a magnetic layer, a protective layer, and a lubricating layer sequentially disposed on the substrate.

[0272] For the magnetic recording medium of this embodiment, one or more base layers may be provided between the substrate and the magnetic layer as needed. Alternatively, an adhesion layer and / or a soft magnetic layer may be provided between the base layer and the substrate.

[0273] Figure 1 A schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0274] In this embodiment, the magnetic recording medium 10 is formed on a substrate 11 with an adhesion layer 12, a soft magnetic layer 13, a first base layer 14, a second base layer 15, a magnetic layer 16, a protective layer 17, and a lubricating layer 18 disposed sequentially.

[0275] "Substrate"

[0276] The substrate 11 can be selected arbitrarily. As the substrate 11, a non-magnetic substrate, for example, on which a film formed of NiP or NiP alloy is formed on a substrate formed of a metal or alloy material such as Al or Al alloy is preferably used.

[0277] Furthermore, as substrate 11, a non-magnetic substrate formed of non-metallic materials such as glass, ceramic, silicon, silicon carbide, carbon, and resin can be used, or a non-magnetic substrate on which a NiP or NiP alloy film is further formed on a substrate formed of these non-metallic materials can be used as substrate 11.

[0278] "Adhesion layer"

[0279] The adhesion layer 12 prevents corrosion of the substrate 11 when the substrate 11 is disposed in contact with the soft magnetic layer 13 disposed on the adhesion layer 12.

[0280] The material of the adhesion layer 12 can be arbitrarily selected, and 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, for example, by sputtering.

[0281] "Soft magnetic layer"

[0282] The soft magnetic layer 13 can be chosen arbitrarily, but it is preferred to have a structure in which a first soft magnetic film, an intermediate layer made of Ru film, and a second soft magnetic film are stacked in sequence. That is, the soft magnetic layer 13 preferably has a structure obtained by sandwiching an intermediate layer made of Ru film between two soft magnetic films, so that the soft magnetic films above and below the intermediate layer are antiferroic coupled (AFC).

[0283] Examples of materials that can be used for the first and second soft magnetic films include CoZrTa alloys and CoFe alloys.

[0284] Preferably, any one of Zr, Ta, and Nb is added to the CoFe alloy used in the first and second soft magnetic films. This promotes the amorphization of the first and second soft magnetic films, improves the orientation of the first substrate layer (seed layer), and reduces the lift of the magnetic head.

[0285] The soft magnetic layer 13 can be formed, for example, by sputtering.

[0286] "First basal layer"

[0287] 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 disposed thereon.

[0288] Examples of first base layers 14 include layers composed of Cr, Ta, Ru, or CrMo alloy layers, CoW alloy layers, CrW alloy layers, CrV alloy layers, CrTi alloy layers, etc.

[0289] The first base layer 14 can be formed, for example, by sputtering.

[0290] "Second basal layer"

[0291] The second substrate layer 15 is a layer controlled in such a way that the orientation of the magnetic layer 16 becomes well. The second substrate layer 15 can be chosen arbitrarily, but is preferably a layer made of Ru or a Ru alloy.

[0292] The second base layer 15 can be a single layer or multiple layers. If the second base layer 15 is composed of multiple layers, all layers can be made of the same material, or at least one layer can be made of a different material.

[0293] The second base layer 15 can be formed, for example, by sputtering.

[0294] "Magnetic layer"

[0295] The magnetic layer 16 is made of a magnetic film with its easy magnetization axis facing vertically or horizontally relative to the substrate surface. The magnetic layer 16 can be chosen arbitrarily, but is preferably a layer containing Co and Pt. Furthermore, in order to improve SNR characteristics, it can be a layer containing oxides, Cr, B, Cu, Ta, Zr, etc.

[0296] Examples of oxides contained in the magnetic layer 16 include SiO2, SiO, Cr2O3, CoO, Ta2O3, and TiO2.

[0297] The magnetic layer 16 can consist of a single layer or multiple magnetic layers composed of different materials.

[0298] For example, when the magnetic layer 16 is composed of three layers stacked sequentially from bottom to top—a first magnetic layer, a second magnetic layer, and a third magnetic layer—the first magnetic layer is preferably a granular structure formed of a material containing Co, Cr, and Pt, and further containing oxides. As the oxide contained in the first magnetic layer, oxides of, for example, Cr, Si, Ta, Al, Ti, Mg, and Co are preferred. Among these, TiO2, Cr2O3, and SiO2 are particularly suitable. Furthermore, the first magnetic layer is preferably formed of a composite oxide containing two or more oxides. Among these, Cr2O3-SiO2, Cr2O3-TiO2, and SiO2-TiO2 are particularly suitable.

[0299] In addition to Co, Cr, Pt, and oxides, the first magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re.

[0300] The second magnetic layer can be made of the same material as the first magnetic layer. The second magnetic layer is preferably granular.

[0301] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, and Pt but not oxides. In addition to Co, Cr, and Pt, the third magnetic layer may also contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn.

[0302] When the magnetic layer 16 is formed of multiple magnetic layers, it is preferable to provide a non-magnetic layer between adjacent magnetic layers. When the magnetic layer 16 is formed of three layers: a first magnetic layer, a second magnetic layer, and a third magnetic layer, it is preferable to provide a non-magnetic layer between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.

[0303] The non-magnetic layer disposed between adjacent magnetic layers of magnetic layer 16 can be, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 represents one or more elements selected from Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Ti, V, B, etc.).

[0304] Preferably, an alloy material comprising oxides, metal nitrides, or metal carbides is used in the non-magnetic layer disposed between adjacent magnetic layers of the magnetic layer 16. Specifically, as oxides, examples include SiO2, Al2O3, Ta2O5, Cr2O3, MgO, Y2O3, TiO2, etc. As metal nitrides, examples include AlN, Si3N4, TaN, CrN, etc. As metal carbides, examples include TaC, BC, SiC, etc.

[0305] Non-magnetic layers can be formed, for example, by sputtering.

[0306] To achieve higher recording density, the magnetic layer 16 is preferably a magnetic layer for perpendicular magnetic recording with its easy magnetization axis oriented perpendicular to the substrate surface. The magnetic layer 16 can also be a magnetic layer for in-plane magnetic recording.

[0307] The magnetic layer 16 can be formed by any conventionally known method, such as vapor deposition, ion beam sputtering, or magnetron sputtering. The magnetic layer 16 is typically formed by sputtering.

[0308] "Protective layer"

[0309] The protective layer 17 protects the magnetic layer 16. The protective layer 17 can be composed of one layer or multiple layers. Examples of materials for the protective layer 17 include carbon, nitrogen-containing carbon, and silicon carbide.

[0310] As the protective layer 17, a carbon-based protective layer is preferred, and an amorphous carbon protective layer is particularly preferred. If the protective layer 17 is a carbon-based protective layer, the interaction with the polar groups (especially hydroxyl groups) contained in the fluorinated ether compound in the lubricating layer 18 is further enhanced, and therefore it is preferred.

[0311] The adhesion between the carbon-based protective layer and the lubricating layer 18 can be controlled by making the carbon-based protective layer hydrogenated carbon and / or nitrided carbon, and adjusting the hydrogen and / or nitrogen content in the carbon-based protective layer. The hydrogen content in the carbon-based protective layer is preferably 3 to 20 atomic percent when measured by hydrogen forward scattering (HFS). Furthermore, the nitrogen content in the carbon-based protective layer is preferably 4 to 15 atomic percent when measured by X-ray photoelectron spectrophotometry (XPS).

[0312] The hydrogen and / or nitrogen contained in the carbon-based protective layer do not need to be uniformly contained throughout the entire carbon-based protective layer. For example, a tilted composition is suitable for the carbon-based protective layer, where nitrogen is contained on the lubrication layer 18 side of the protective layer 17 and hydrogen is contained on the magnetic layer 16 side of the protective layer 17. In this case, the adhesion between the magnetic layer 16 and the lubrication layer 18 and the carbon-based protective layer is further improved.

[0313] The thickness of the protective layer 17 is preferably 1 nm to 7 nm. If the thickness of the protective layer 17 is 1 nm or more, the performance of the protective layer 17 can be fully obtained. If the thickness of the protective layer 17 is 7 nm or less, it is preferred from the viewpoint of thinning the protective layer 17.

[0314] The film formation method for the protective layer 17 can be a sputtering method using a carbon-containing target, a CVD (chemical vapor deposition) method using hydrocarbon raw materials such as ethylene and toluene, or an IBD (ion beam deposition) method.

[0315] When forming a carbon-based protective layer as protective layer 17, the film can be formed, for example, by DC magnetron sputtering. In particular, when forming a carbon-based protective layer as protective layer 17, it is preferable to form an amorphous carbon protective layer by plasma CVD. The amorphous carbon protective layer formed by plasma CVD has a uniform surface and low roughness.

[0316] "Lubrication layer"

[0317] The lubricating layer 18 prevents contamination of the magnetic recording medium 10. In addition, the lubricating layer 18 reduces the friction of the magnetic head of the magnetic recording and playback device that slides on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10.

[0318] like Figure 1 As shown, the lubricating layer 18 is formed in contact with the protective layer 17. The lubricating layer 18 contains the aforementioned fluorinated ether compound.

[0319] When the protective layer 17 disposed beneath the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 is bonded to the protective layer 17 with a particularly strong adhesion. As a result, it is easy to obtain a magnetic recording medium 10 in which the surface of the protective layer 17 is covered with a high coverage even when the thickness of the lubricating layer 18 is thin, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented.

[0320] The average film thickness of the lubricating layer 18 can be arbitrarily selected, but is preferably [specific thickness]. More preferably If the average film thickness of the lubricating layer 18 is 0.5 nm or more, the lubricating layer 18 will not form islands or meshes but will be formed with a uniform film thickness. Therefore, the surface of the protective layer 17, which is covered with a high coverage rate through the lubricating layer 18, is less likely to experience film thickness reduction due to peeling. Furthermore, by making the average film thickness of the lubricating layer 18 2.0 nm or less, the lubricating layer 18 can be sufficiently thinned, and the rise of the magnetic head can be kept sufficiently small.

[0321] If the surface of the protective layer 17 is not covered by the lubricating layer 18 with a sufficiently high coverage, environmental substances adsorbed on the surface of the magnetic recording medium 10 can penetrate through the gaps in the lubricating layer 18 and infiltrate below the lubricating layer 18. These environmental substances penetrating below the lubricating layer 18 adsorb and combine with the protective layer 17 to generate contaminants. Furthermore, during magnetic recording reproduction, these contaminants (agglomerated components) adhere (transfer) to the magnetic head as stains, causing head damage or reducing the magnetic recording reproduction characteristics of the magnetic recording reproduction device.

[0322] Examples of environmental substances that contribute to the formation of pollutants include, for example, siloxane compounds (cyclic siloxanes, linear siloxanes), ionic impurities, high molecular weight hydrocarbons such as octadecane, and plasticizers such as dioctyl phthalate. Examples of metal ions included as ionic impurities include, for example, sodium ions and potassium ions. Examples of inorganic ions included as ionic impurities include, for example, chloride ions, bromide ions, nitrate ions, sulfate ions, and ammonium ions. Examples of organic ions included as ionic impurities include, for example, oxalate ions and formate ions.

[0323] "Methods for forming a lubricating layer"

[0324] As a method for forming the lubricating layer 18, for example, a magnetic recording medium in the manufacturing process in which layers up to the protective layer 17 are formed on the substrate 11 is prepared, a lubricating layer forming solution is applied to the protective layer 17, and then dried.

[0325] The lubricating layer forming solution is obtained by dispersing and dissolving the lubricant for the magnetic recording medium described in the above embodiments in a solvent as needed, thereby achieving a viscosity and concentration suitable for the coating method.

[0326] Solvents used in solutions for forming lubricating layers include, for example, fluorinated solvents such as Bartel XF (trade name, manufactured by Mitsui Dupont Fluorokemica Co., Ltd.).

[0327] There are no particular limitations on the coating method of the solution for forming the lubricating layer. Examples include spin coating, spray coating, paper coating, and impregnation.

[0328] When using the immersion method, the following method can be used, for example. First, a substrate 11, with each layer up to the protective layer 17, is immersed in a lubricant layer forming solution added to the immersion tank of the immersion coating apparatus. Then, the substrate 11 is pulled out of the immersion tank at a predetermined speed. As a result, the lubricant layer forming solution is coated onto the surface of the protective layer 17 on the substrate 11.

[0329] By using the impregnation method, the lubricating layer forming solution can be uniformly coated on 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.

[0330] In this embodiment, it is preferable to perform heat treatment on the substrate 11 on which the lubricating layer 18 is formed. By performing heat treatment, the adhesion between the lubricating layer 18 and the protective layer 17 is improved, and the bonding force between the lubricating layer 18 and the protective layer 17 is enhanced.

[0331] The heat treatment temperature is preferably 100–180°C. If the heat treatment temperature is above 100°C, the effect of improving the adhesion between the lubricating layer 18 and the protective layer 17 can be sufficiently achieved. Furthermore, by keeping the heat treatment temperature below 180°C, thermal decomposition of the lubricating layer 18 can be prevented. The heat treatment time is preferably 10–120 minutes.

[0332] The magnetic recording medium 10 of this embodiment has at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 sequentially disposed on a substrate 11. In the magnetic recording medium 10 of this embodiment, a lubricating layer 18 comprising the aforementioned fluorinated ether compound is formed in contact with the protective layer 17. Even though the lubricating layer 18 is thin, it covers the surface of the protective layer 17 with a high coverage rate. Therefore, the lubricating layer 18 in the magnetic recording medium 10 of this embodiment has excellent wear resistance and shedding resistance.

[0333] Furthermore, in the magnetic recording medium 10 of this embodiment, the surface of the protective layer 17 is covered with a high coverage by the lubricating layer 18. Therefore, environmental substances that generate contaminants, such as ionic impurities, can be prevented from intruding through the gaps in the lubricating layer 18. Thus, the magnetic recording medium 10 of this embodiment has fewer contaminants on its surface. In addition, the lubricating layer 18 in the magnetic recording medium 10 of this embodiment is less prone to the generation of foreign matter (stains), which can suppress pickup.

[0334] In summary, the magnetic recording medium 10 of this embodiment has excellent reliability and durability.

[0335] Example

[0336] The present invention will be further described in detail below through examples and comparative examples. However, the present invention is not limited to the following examples.

[0337] "Lubricant Manufacturing"

[0338] (Example 1)

[0339] The compound shown in formula (A) above was produced by the method shown below.

[0340] First, 4-aminobutyronitrile was reacted with di-tert-butyl dicarbonate in methanol to obtain the compound. Then, the obtained compound was reacted with epibromool to synthesize the compound shown in formula (20).

[0341]

[0342] (In equation (20), t-Bu represents tert-butyl.)

[0343] Next, under a nitrogen atmosphere, HOCH2CF2O(CF2CF2O) was added to a 200 mL flask. m (CF2O) n 20 g of fluorinated polyether (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m represents the average degree of polymerization and n represents the average degree of polymerization 4.5) , 10.6 g of the compound represented by formula (20) (molecular weight 240.30, 44 mmol) and 20 mL of tert-butanol were stirred at room temperature until homogeneous.

[0344] 0.90 g of potassium tert-butoxide (molecular weight 112.21, 8 mmol) was added to the homogeneous liquid, and the mixture was stirred at 70 °C for 14 hours to allow the reaction to proceed. The resulting reaction product was cooled to 25 °C, neutralized with 1 mol / L hydrochloric acid, extracted with hydrochloric acid (registered trademark) XF, and washed with water. The organic layer was dehydrated with anhydrous sodium sulfate, filtered to separate the layers using a drying agent, and the filtrate was concentrated.

[0345] 15 mL of trifluoroacetic acid was added to the concentrated filtrate, and the mixture was stirred at 25 °C for 3 hours to allow the reaction to proceed. The reaction solution was transferred to a beaker containing 70 mL of 8% sodium bicarbonate solution and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with water and dehydrated using anhydrous sodium sulfate. After filtration with a drying agent, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 12.8 g of compound (A). In formula (A), ma, representing the average degree of polymerization, is 4.5, and na, representing the average degree of polymerization, is 4.5.

[0346] The resulting compound (A) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0347] Compound (A); 1 H-NMR (CD3COCD3);

[0348] δ[ppm]1.8(4H), 2.5(4H), 3.4~3.9(22H)

[0349] (Example 2)

[0350] Instead of the compound shown in formula (20), 11.2 g of the compound shown in formula (21) was used, and the same procedure as in Example 1 was performed to obtain 13.1 g of compound (B). In formula (B), mb, which represents the average degree of polymerization, is 4.5, and nb, which represents the average degree of polymerization, is 4.5.

[0351] The compound shown in formula (21) was synthesized by reacting a compound obtained by reacting 5-aminopentanilide with di-tert-butyl dicarbonate in methanol and then reacting it with epibromool.

[0352]

[0353] (In equation (21), t-Bu represents tert-butyl.)

[0354] The resulting compound (B) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0355] Compound (B); 1 H-NMR (CD3COCD3);

[0356] δ[ppm]1.6~2.0(6H), 2.2~2.4(2H), 2.5(4H), 3.4~4.0(22H)

[0357] (Example 3)

[0358] Instead of the compound shown in formula (20), 10.6 g of the compound shown in formula (22) was used, and otherwise the same operation as in Example 1 was performed to obtain 12.8 g of compound (C). In formula (C), mc, which represents the average degree of polymerization, is 4.5, and nc, which represents the average degree of polymerization, is 4.5.

[0359] The compound shown in formula (22) was synthesized by reacting epibromool with the amino group of 3-amino-2-methylpropionitrile protected with di-tert-butyl dicarbonate.

[0360]

[0361] (In equation (22), t-Bu represents tert-butyl.)

[0362] The resulting compound (C) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0363] Compound (C); 1 H-NMR (CD3COCD3);

[0364] δ[ppm]1.4(6H), 3.4~4.0(24H)

[0365] (Example 4)

[0366] Instead of the compound shown in formula (20), 13.8 g of the compound shown in formula (23) was used, and otherwise the same operation as in Example 1 was performed to obtain 14.3 g of compound (D). In formula (D), md, which represents the average degree of polymerization, is 4.5, and nd, which represents the average degree of polymerization, is 4.5.

[0367] The compound shown in formula (23) is synthesized by reacting the compound shown in formula (20) with glycidol.

[0368]

[0369] (In equation (23), t-Bu represents tert-butyl.)

[0370] The resulting compound (D) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0371] Compound (D); 1 H-NMR (CD3COCD3);

[0372] δ[ppm]1.8(4H), 2.5(4H), 3.4~3.9(34H)

[0373] (Example 5)

[0374] Instead of the compound shown in formula (20), 18.8 g of the compound shown in formula (24) was used, and otherwise the same operation as in Example 1 was performed to obtain 14.5 g of compound (E). In formula (E), me, which represents the average degree of polymerization, is 4.5, and ne, which represents the average degree of polymerization, is 4.5.

[0375] The compound shown in formula (24) was synthesized by reacting the compound shown in formula (20) with 3-buten-1-amine whose amino group was protected by di-tert-butyl dicarbonate, and by oxidizing the double bond of the resulting compound.

[0376]

[0377] (In equation (24), t-Bu represents tert-butyl.)

[0378] The resulting compound (E) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0379] Compound (E); 1H-NMR (CD3COCD3);

[0380] δ[ppm]1.6~2.0(10H), 2.2~2.4(2H), 2.5(4H), 3.4~3.9(32H)

[0381] (Example 6)

[0382] Instead of the compound shown in formula (20), 14.8 g of the compound shown in formula (29) was used, and otherwise the same operation as in Example 1 was performed to obtain 14.5 g of compound (F). In formula (F), mf, which represents the average degree of polymerization, is 4.5, and nf, which represents the average degree of polymerization, is 4.5.

[0383] The compound shown in formula (29) was synthesized by the following method.

[0384] First, 4-hydroxybutyronitrile was reacted with epibromoethanol to synthesize the compound shown in formula (25). Next, the compound shown in formula (25) was reacted with 2-propen-1-amine, whose amino group was protected by di-tert-butyl dicarbonate, to synthesize the compound shown in formula (26). Next, the compound shown in formula (26) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (27). Next, the compound shown in formula (27) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (28). Then, the double bond of the compound shown in formula (28) was oxidized to synthesize the compound shown in formula (29).

[0385]

[0386] (In equations (26) to (29), t-Bu represents tert-butyl.)

[0387] The resulting compound (F) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0388] Compound (F); 1 H-NMR (CD3COCD3);

[0389] δ[ppm]1.8(4H), 2.5(4H), 3.4~4.0(32H)

[0390] (Example 7)

[0391] Instead of the compound shown in formula (20), 18.1 g of the compound shown in formula (31) was used, and otherwise the same operation as in Example 1 was performed to obtain 14.3 g of compound (G). In formula (G), mg represents the average degree of polymerization and ng represents the average degree of polymerization.

[0392] The compound shown in formula (31) was synthesized by using the compound shown in formula (30) instead of the compound shown in formula (25), except that the same operations as those for the synthesis of the compound shown in formula (29) were performed.

[0393] The compound shown in formula (30) is synthesized by reacting a compound obtained by protecting one side of the hydroxyl group of 1,3-propanediol with dihydropyran with epibromoethanol.

[0394]

[0395] (In equation (31), t-Bu represents tert-butyl.)

[0396] The resulting compound (G) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0397] Compound (G); 1 H-NMR (CD3COCD3);

[0398] δ[ppm]1.8(4H), 2.5(4H), 3.4~4.0(34H)

[0399] (Example 8)

[0400] The compound represented by formula (H) above was produced by the method shown below.

[0401] Under a nitrogen atmosphere, add HOCH2CF2O(CF2CF2O) to a 100mL eggplant-shaped flask. m (CF2O) n 20.0 g of a fluorinated polyether (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m represents the average degree of polymerization and n represents the average degree of polymerization 4.5) was mixed with 2.88 g of the compound represented by formula (20) above and 12 mL of tert-butanol, and stirred at room temperature until homogeneous. 0.674 g of potassium tert-butoxide was further added to this homogeneous liquid, and the mixture was stirred at 70 °C for 8 hours to allow the reaction to proceed and obtain the reaction product.

[0402] The resulting reaction product was cooled to 25°C, neutralized with 0.5 mol / L hydrochloric acid, extracted with Biotelle XF (registered trademark), the organic layer was washed with water, and dehydrated using anhydrous sodium sulfate. After separation by filtration with a desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 9.93 g of the compound shown in formula (32).

[0403]

[0404] (In equation (32), mh represents the average degree of polymerization and nh represents the average degree of polymerization. t-Bu represents tert-butyl.)

[0405] In a 200 mL flask under a nitrogen atmosphere, 6.20 g of the compound shown in formula (32) above, 1.21 g of the compound shown in formula (33) below, and 50 mL of tert-butanol were added and stirred at room temperature until homogeneous. 0.168 g of potassium tert-butoxide was then added to the homogeneous liquid, and the mixture was stirred at 70 °C for 16 hours to allow the reaction to proceed.

[0406] The compound shown in formula (33) is synthesized by reacting a compound in which one side of the hydroxyl group of ethylene glycol is protected with dihydropyran with epibromool.

[0407]

[0408] The reacted liquid was brought to room temperature, and 20 g of a 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%), manufactured by Tokyo Chemical Industry Co., Ltd.) was added. The mixture was stirred at room temperature for 1 hour. The reaction solution was transferred to a beaker containing 70 mL of 8% sodium bicarbonate solution and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with water and dehydrated using anhydrous sodium sulfate. After filtration to separate the layers using a drying agent, the filtrate was concentrated.

[0409] 15 mL of trifluoroacetic acid was added to the concentrated filtrate, and the mixture was stirred at 25 °C for 3 hours to allow the reaction to proceed. The reaction solution was transferred to a beaker containing 70 mL of 8% sodium bicarbonate solution and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with water and dehydrated using anhydrous sodium sulfate. After filtration with a drying agent, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 4.40 g of compound (H). In formula (H), mh, representing the average degree of polymerization, is 4.5, and nh, representing the average degree of polymerization, is 4.5.

[0410] The resulting compound (H) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0411] Compound (H);1 H-NMR (CD3COCD3);

[0412] δ[ppm]1.8(2H), 2.5(2H), 3.4~4.2(24H)

[0413] (Example 9)

[0414] Instead of the compound shown in formula (33), 1.91 g of the compound shown in formula (34) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.81 g of compound (I). In formula (I), mi, which represents the average degree of polymerization, is 4.5, and ni, which represents the average degree of polymerization, is 4.5.

[0415] The compound shown in formula (34) was synthesized by reacting a compound obtained by protecting one side of the hydroxyl group of 1,3-propanediol with dihydropyran with bis(2-epoxyethylene ethyl) ether.

[0416]

[0417] The resulting compound (I) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0418] Compound (I); 1 H-NMR (CD3COCD3);

[0419] δ[ppm]1.6~2.0(6H), 2.2~2.4(2H), 2.5(2H), 3.3~4.2(30H)

[0420] (Example 10)

[0421] Instead of the compound shown in formula (33), 1.52 g of the compound shown in formula (35) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.53 g of compound (J). In formula (J), mj, representing the average degree of polymerization, is 4.5, and nj, representing the average degree of polymerization, is 4.5.

[0422] The compound shown in formula (35) was synthesized by reacting a compound obtained by reacting 4-aminobutyronitrile with di-tert-butyl dicarbonate in methanol with 2-(2-bromoethyl)ethylene oxide.

[0423]

[0424] (In equation (35), t-Bu represents tert-butyl.)

[0425] The resulting compound (J) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0426] Compound (J); 1 H-NMR (CD3COCD3);

[0427] δ[ppm]1.6~2.0(5H), 2.2~2.4(1H), 2.5(4H), 3.3~4.2(22H)

[0428] (Example 11)

[0429] Instead of the compound shown in formula (33), 2.81 g of the compound shown in formula (40) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.98 g of compound (K). In formula (K), mk, which represents the average degree of polymerization, is 4.5, and nk, which represents the average degree of polymerization, is 4.5.

[0430] The compound shown in formula (40) was synthesized by the following method.

[0431] First, the double bond on one side of a compound obtained by reacting di-4-pentenylamine with di-tert-butyl dicarbonate in methanol was oxidized to synthesize the compound shown in formula (36). Next, the compound shown in formula (36) was reacted with a compound obtained by protecting one side of the hydroxyl group of 1,4-butanediol with dihydropyran to synthesize the compound shown in formula (37). Next, the compound shown in formula (37) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (38). Next, the compound shown in formula (38) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (39). Then, the double bond of the compound shown in formula (39) was oxidized to synthesize the compound shown in formula (40).

[0432]

[0433] (In equations (36) to (40), t-Bu represents tert-butyl.)

[0434] The resulting compound (K) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0435] Compound (K); 1 H-NMR (CD3COCD3);

[0436] δ[ppm]1.6~2.0(8H), 2.2~2.4(2H), 2.5(2H), 3.3~4.2(34H)

[0437] (Example 12)

[0438] Instead of the compound shown in formula (33), 2.11 g of the compound shown in formula (45) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.87 g of compound (L). In formula (L), ml, which represents the average degree of polymerization, is 4.5, and nl, which represents the average degree of polymerization, is 4.5.

[0439] The compound shown in formula (45) was synthesized by the following method.

[0440] First, the double bond on one side of the compound obtained by reacting di-3-butenylamine with di-tert-butyl dicarbonate in methanol was oxidized to synthesize the compound shown in formula (41). Next, the compound shown in formula (41) was reacted with 4-hydroxybutyronitrile to synthesize the compound shown in formula (42). Next, the compound shown in formula (42) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (43). Next, the compound shown in formula (43) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (44). Then, the double bond of the compound shown in formula (44) was oxidized to synthesize the compound shown in formula (45).

[0441]

[0442] (In equations (41) to (45), t-Bu represents tert-butyl.)

[0443] The resulting compound (L) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0444] Compound (L); 1 H-NMR (CD3COCD3);

[0445] δ[ppm]1.6~2.0(6H), 2.2~2.4(2H), 2.5(2H), 3.3~4.2(29H)

[0446] (Example 13)

[0447] Instead of the compound shown in formula (33), 2.35 g of the compound shown in formula (46) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.43 g of compound (M). In formula (M), mm, representing the average degree of polymerization, is 4.5, and nm, representing the average degree of polymerization, is 4.5.

[0448] The compound shown in formula (46) was synthesized by reacting a compound obtained by reacting propargylamine with di-tert-butyl dicarbonate in methanol with 2-(2-bromoethyl)ethylene oxide.

[0449]

[0450] (In equation (46), t-Bu represents tert-butyl.)

[0451] The resulting compound (M) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0452] Compound (M); 1 H-NMR (CD3COCD3);

[0453] δ[ppm]1.6~2.0(3H), 2.2~2.4(1H), 2.5(2H), 2.7(1H), 3.3~4.2(22H)

[0454] (Example 14)

[0455] Instead of the compound shown in formula (33), 1.29 g of the compound shown in formula (47) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.39 g of compound (N). In formula (N), mn, which represents the average degree of polymerization, is 4.5, and nn, which represents the average degree of polymerization, is 4.5.

[0456] The compound shown in formula (47) was synthesized by reacting a compound in methanol with 1-propylamine and di-tert-butyl dicarbonate, and then with epibromool.

[0457]

[0458] (In equation (47), t-Bu represents tert-butyl.)

[0459] The resulting compound (N) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0460] Compound (N); 1 H-NMR (CD3COCD3);

[0461] δ[ppm]0.9~1.1(5H), 1.8(2H), 2.5(2H), 3.4~4.2(22H)

[0462] (Example 15)

[0463] Instead of the compound shown in formula (33), 1.67 g of the compound shown in formula (48) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.62 g of compound (O). In formula (O), mo, which represents the average degree of polymerization, is 4.5, and no, which represents the average degree of polymerization, is 4.5.

[0464] The compound shown in formula (48) is synthesized by reacting a compound obtained by reacting p-anisidine with di-tert-butyl dicarbonate in methanol with epibromool.

[0465]

[0466] (In formula (48), t-Bu represents tert-butyl and Me represents methyl.)

[0467] The resulting compound (O) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0468] Compound (O); 1 H-NMR (CD3COCD3);

[0469] δ[ppm]1.8(2H), 2.5(2H), 2.7(1H), 3.3~4.2(21H)6.8(4H), 7.4(1H)

[0470] (Example 16)

[0471] Instead of the compound shown in formula (33), 2.32 g of the compound shown in formula (49) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.64 g of compound (P). In formula (P), mp, which represents the average degree of polymerization, is 4.5, and np, which represents the average degree of polymerization, is 4.5.

[0472] The compound represented by formula (49) was synthesized by the following method. Allylamine was reacted with di-tert-butyl dicarbonate in methanol to obtain compound 1. The obtained compound 1 was reacted with sodium hydroxide and epibromoethanol to obtain compound 2. Next, the double bond on one side of compound 2 was oxidized. Through the above steps, the compound represented by formula (49) was obtained.

[0473]

[0474] (In equation (49), t-Bu represents tert-butyl.)

[0475] The resulting compound (P) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0476] Compound (P); 1 H-NMR (CD3COCD3);

[0477] δ[ppm]1.8(2H), 2.5(2H), 3.3~4.2(29H), 5.1~5.2(1H), 5.8~6.0(1H), 7.4(1H)

[0478] (Example 17)

[0479] Instead of the compound shown in formula (33), 2.54 g of the compound shown in formula (53) was used, and otherwise the same operation as in Example 8 was performed to obtain 4.77 g of compound (Q). In formula (Q), mq, which represents the average degree of polymerization, is 4.5, and nq, which represents the average degree of polymerization, is 4.5.

[0480] The compound shown in formula (53) was synthesized by the following method.

[0481] First, the compound obtained by reacting 3-butenylamine with di-tert-butyl dicarbonate in methanol was reacted with sodium hydroxide and epibromoethanol to synthesize the compound shown in formula (50). Next, the compound shown in formula (50) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (51). Next, the compound shown in formula (51) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (52). Then, the double bond on one side of the compound shown in formula (52) was oxidized to synthesize the compound shown in formula (53).

[0482]

[0483] (In equations (50) to (53), t-Bu represents tert-butyl.)

[0484] The resulting compound (Q) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0485] Compound (Q); 1 H-NMR (CD3COCD3);

[0486] δ[ppm]1.6~2.0(5H), 2.2~2.4(1H), 2.5(2H), 3.3~4.2(28H), 5.1~5.2(1H), 5.8~6.0(1H), 7.4(1H)

[0487] (Example 18)

[0488] Instead of the compound shown in formula (20), 1.69 g of the compound shown in formula (25) was used, and instead of the compound shown in formula (33), 2.32 g of the compound shown in formula (55) was used. Otherwise, the same operation as in Example 8 was performed, and 5.00 g of compound (R) was obtained through the intermediate shown in formula (54). In formula (R), mr, which represents the average degree of polymerization, is 4.5, and nr, which represents the average degree of polymerization, is 4.5.

[0489] The compound shown in formula (55) is obtained by oxidizing the double bond of the compound shown in formula (26) and then reacting it with glycidol.

[0490]

[0491] (In equation (54), mr, representing the average degree of polymerization, is 4.5, and nr, representing the average degree of polymerization, is 4.5.)

[0492] (In equation (55), t-Bu represents tert-butyl.)

[0493] The resulting compound (R) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0494] Compound (R); 1 H-NMR (CD3COCD3);

[0495] δ[ppm]1.8(4H), 3.3~4.2(37H)

[0496] (Example 19)

[0497] Instead of the compound shown in formula (55), 2.97 g of the compound shown in formula (60) was used, and otherwise the same operation as in Example 18 was performed to obtain 5.08 g of compound (S). In formula (S), ms represents the average degree of polymerization and ns represents the average degree of polymerization.

[0498] The compound shown in formula (60) was synthesized by the following method.

[0499] First, a compound obtained by reacting a compound in methanol with di-tert-butyl dicarbonate containing a hydroxyl group protected with dihydropyran was reacted with bis(2-epoxyethylene ethyl) ether to synthesize the compound shown in formula (56). Next, the compound shown in formula (56) was reacted with allyl alcohol to synthesize the compound shown in formula (57). Next, the compound shown in formula (57) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (58). Next, the compound shown in formula (58) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (59). Then, the double bond of the compound shown in formula (59) was oxidized to synthesize the compound shown in formula (60).

[0500]

[0501] (In equations (56) to (60), t-Bu represents tert-butyl.)

[0502] The resulting compound (S) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0503] Compound (S); 1 H-NMR (CD3COCD3);

[0504] δ[ppm]1.6~2.0(4H), 2.2~2.4(2H), 3.3~4.2(36H)

[0505] (Example 20)

[0506] Instead of the compound shown in formula (55), 2.63 g of the compound shown in formula (65) was used, and otherwise the same operation as in Example 18 was performed to obtain 5.18 g of compound (T). In formula (T), mt, which represents the average degree of polymerization, is 4.5, and nt, which represents the average degree of polymerization, is 4.5.

[0507] The compound shown in formula (65) was synthesized by the following method.

[0508] First, allyl alcohol was reacted with 2-(3-bromopropyl)ethylene oxide to synthesize the compound shown in formula (61). Next, the compound obtained by reacting 4-aminobutyronitrile with di-tert-butyl dicarbonate in methanol was reacted with the compound shown in formula (61) to synthesize the compound shown in formula (62). Next, the compound shown in formula (62) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (63). Next, the compound shown in formula (63) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (64). Then, the double bond of the compound shown in formula (64) was oxidized and reacted with 2-(hydroxyethyl)ethylene oxide to synthesize the compound shown in formula (65).

[0509]

[0510] (In equations (62) to (65), t-Bu represents tert-butyl.)

[0511] The resulting compound (T) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0512] Compound (T); 1 H-NMR (CD3COCD3);

[0513] δ[ppm]1.6~2.0(7H), 2.2~2.4(1H), 2.5(2H), 3.4~4.0(36H)

[0514] (Example 21)

[0515] Instead of the compound shown in formula (20), 13.69 g of the compound shown in formula (69) was used, and instead of the compound shown in formula (33), 1.28 g of the compound shown in formula (71) was used. Otherwise, the same operation as in Example 8 was performed, and 4.62 g of compound (U) was obtained through the intermediate shown in formula (70). In formula (U), mu, which represents the average degree of polymerization, is 4.5, and nu, which represents the average degree of polymerization, is 4.5.

[0516] The compound shown in formula (69) was synthesized by the following method.

[0517] First, the compound obtained by reacting 2-(aminomethyl)butane-1,4-diol with di-tert-butyl dicarbonate in methanol was reacted with 4-bromo-1-butene to synthesize the compound shown in formula (66). Next, the compound shown in formula (66) was reacted with pyridine and p-toluenesulfonyl chloride to synthesize the compound shown in formula (67). Next, the compound shown in formula (67) was reacted with trimethylsilyl cyanide and tetra-n-butylammonium fluoride to synthesize the compound shown in formula (68). Then, the double bond of the compound shown in formula (68) was oxidized to synthesize the compound shown in formula (69).

[0518] The compound shown in formula (71) is synthesized by reacting diallylamine with di-tert-butyl dicarbonate in methanol, and by oxidizing the double bond on one side of the resulting compound.

[0519]

[0520] (In equations (66) to (71), t-Bu represents tert-butyl.)

[0521] (In equation (70), mu, representing the average degree of polymerization, is 4.5, and nu, representing the average degree of polymerization, is 4.5.)

[0522] The resulting compound (U) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0523] Compound (U); 1 H-NMR (CD3COCD3);

[0524] δ[ppm]1.6~2.0(4H), 2.2~2.4(1H), 3.4~3.9(26H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~6.0(1H)

[0525] (Example 22)

[0526] Instead of the compound shown in formula (71), 2.93 g of the compound shown in formula (73) was used, and otherwise the same operation as in Example 21 was performed to obtain 4.97 g of compound (V). In formula (V), mv, which represents the average degree of polymerization, is 4.5, and nv, which represents the average degree of polymerization, is 4.5.

[0527] The compound shown in formula (73) is synthesized by reacting the compound shown in formula (72) with allyl alcohol.

[0528] The compound shown in formula (72) is synthesized by oxidizing the double bond of the compound shown in formula (50).

[0529]

[0530] (In equations (72) and (73), t-Bu represents tert-butyl.)

[0531] The resulting compound (V) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0532] Compound (V); 1 H-NMR (CD3COCD3);

[0533] δ[ppm]3.4~3.9(25H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~6.0(1H)

[0534] (Example 23)

[0535] Replace HOCH2CF2O(CF2CF2O) m (CF2O) n The fluorinated polyether represented by CF2CH2OH (where m represents the average degree of polymerization and n represents the average degree of polymerization and n is 4.5) was used, while HOCH2CF2O (CF2CF2O) was used instead. w The fluoropolyether represented by CF2CH2OH (where w represents the average degree of polymerization, which is 7.0) was subjected to the same operation as in Example 16 as an intermediate, and was processed by the compound represented by the following formula (74) to obtain 4.61 g of the compound represented by formula (W). In formula (W), w represents the average degree of polymerization, which is 7.0.

[0536]

[0537] (In equation (74), w represents the average degree of polymerization and is 7.0. t-Bu represents tert-butyl.)

[0538] The resulting compound (W) was subjected to... 1The structure was identified by H-NMR measurements, and the following results were obtained.

[0539] Compound (W); 1 H-NMR (CD3COCD3);

[0540] δ[ppm]1.8(2H), 2.5(2H), 3.3~4.2(29H), 5.1~5.2(1H), 5.8~6.0(1H), 7.4(1H)

[0541] (Example 24)

[0542] Replace HOCH2CF2O(CF2CF2O) m (CF2O) n The fluorinated polyether represented by CF2CH2OH (where m represents the average degree of polymerization and n represents the average degree of polymerization and n is 4.5) was used, while HOCH2CF2CF2O (CF2CF2CF2O) was used. x The fluoropolyether represented by CF2CF2CH2OH (where x represents the average degree of polymerization of 4.5) was subjected to the same operation as in Example 16 as an intermediate, and was processed by the compound represented by the following formula (75) to obtain 4.54 g of the compound represented by formula (X).

[0543] In equation (X), x represents the average degree of polymerization, which is 4.5.

[0544]

[0545] (In equation (75), x represents the average degree of polymerization and is 4.5. t-Bu represents tert-butyl.)

[0546] The resulting compound (X) was subjected to... 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0547] Compound (X); 1 H-NMR (CD3COCD3);

[0548] δ[ppm]1.8(2H), 2.5(2H), 3.3~4.2(29H), 5.1~5.2(1H), 5.8~6.0(1H), 7.4(1H)

[0549] (Example 25)

[0550] Replace HOCH2CF2O(CF2CF2O) m (CF2O) nThe fluorinated polyether represented by CF2CH2OH (where m represents the average degree of polymerization and n represents the average degree of polymerization and n is 4.5) was used, while HOCH2CF2CF2CF2O (CF2CF2CF2CF2O) was used. y The fluoropolyether represented by CF2CF2CF2CH2OH (where y represents the average degree of polymerization, which is 3.0) was subjected to the same operation as in Example 16 as an intermediate, and was processed by the compound represented by the following formula (76) to obtain 4.53 g of the compound represented by formula (Y). In formula (Y), y represents the average degree of polymerization, which is 3.0.

[0551]

[0552] (In equation (76), y represents the average degree of polymerization and is 3.0. t-Bu represents tert-butyl.)

[0553] The resulting compound (Y) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0554] Compound (Y); 1 H-NMR (CD3COCD3);

[0555] δ[ppm]1.8(2H), 2.5(2H), 3.3~4.2(29H), 5.1~5.2(1H), 5.8~6.0(1H), 7.4(1H)

[0556] (Example 26)

[0557] Replace HOCH2CF2O(CF2CF2O) m (CF2O) n The fluorinated polyether represented by CF2CH2OH (where m represents the average degree of polymerization and n represents the average degree of polymerization and n is 4.5) was used, while HOCH2CF(CF3)(OCF(CF3)CF2) was used. z The fluorinated polyether represented by OCF(CF3)CH2OH (where z represents the average degree of polymerization of 4.5) was subjected to the same operation as in Example 16 as an intermediate, and was processed by the compound represented by the following formula (77) to obtain 4.57 g of the compound represented by formula (Z).

[0558] In equation (Z), z represents the average degree of polymerization, which is 4.5.

[0559]

[0560] (In equation (77), z represents the average degree of polymerization, which is 4.5. t-Bu represents tert-butyl.)

[0561] The resulting compound (Z) was subjected to 1 The structure was identified by H-NMR measurements, and the following results were obtained.

[0562] Compound (Z); 1 H-NMR (CD3COCD3);

[0563] δ[ppm]1.8(2H), 2.5(2H), 3.3~4.2(29H), 5.1~5.2(1H), 5.8~6.0(1H), 7.4(1H)

[0564] Substituting the compounds of Examples 1-26 obtained in this manner into the R of formula (1) 1 The terminal base shown, R 2 The connecting bases shown (X in [A] and X in [B] of equation (2)) and R 3 The PFPR chain and R shown 4 The connecting base shown (X in [C] and X in [D] of equation (3)), R 5 The structures of the terminal groups shown are illustrated in Tables 1 to 3.

[0565] In Tables 1 to 3, R in the compounds of Examples 1 to 26 2 When there are two or more [A] and [B] in equation (2), the one closest to R will be... 3 The side [A] or [B] is recorded at the top, below which is R. 3 Side to R 1 The following are listed sequentially. Furthermore, R in the compounds of Examples 1-26... 4 When there are more than two [C] and [D] in equation (3), the one closest to R will be... 3 The [C] or [D] on the side is recorded at the top, below which is R. 3 Side to R 5 Recorded sequentially from the side.

[0566] In addition, the number of secondary amines [-NH-], the number of hydroxyl groups [-OH], the number of cyano groups [-CN], and the total number of secondary amines [-NH-], hydroxyl groups [-OH], and cyano groups [-CN] contained in the molecules of the compounds of Examples 1 to 26 are shown in Tables 1 to 3.

[0567]

[0568]

[0569]

[0570] Comparative Example 1

[0571] The compound represented by the following formula (AA) was synthesized by the method described in Patent Document 3.

[0572]

[0573] (In equation (AA), jA, representing the average degree of polymerization, is 4.5, and kA, representing the average degree of polymerization, is 4.5.)

[0574] Comparative Example 2

[0575] The compound shown in formula (AB) was synthesized by the method described in Patent Document 2.

[0576]

[0577] (In equation (AB), jB, representing the average degree of polymerization, is 4.5, and kB, representing the average degree of polymerization, is 4.5.)

[0578] Comparative Example 3

[0579] The compound represented by the following formula (AC) was synthesized by the method described in Patent Document 1.

[0580]

[0581] (In equation (AC), jC, representing the average degree of polymerization, is 4.5, and kC, representing the average degree of polymerization, is 4.5.)

[0582] The number-average molecular weights (Mn) of the compounds of Examples 1-26 and Comparative Examples 1-3 obtained by the above method were determined. The results are shown in Table 4.

[0583] Table 4

[0584]

[0585] Next, a lubricant layer forming solution was prepared using the compounds obtained in Examples 1-26 and Comparative Examples 1-3, according to the method shown below. Then, using the obtained lubricant layer forming solution, a lubricant layer of the magnetic recording medium was formed using the method shown below, thus obtaining the magnetic recording media of Examples 1-26 and Comparative Examples 1-3.

[0586] "Solution for forming a lubricating layer"

[0587] The compounds obtained in Examples 1-26 and Comparative Examples 1-3 were dissolved in Virtue (registered trademark) XF, respectively, to obtain the film thickness when coated on the protective layer. A solution for forming a lubricating layer was prepared by diluting it with Vertral (registered trademark) XF.

[0588] "Magnetic recording medium"

[0589] A magnetic recording medium is prepared by sequentially depositing an adhesion layer, a soft magnetic layer, a first base layer, a second base layer, a magnetic layer, and a protective layer on a substrate with a diameter of 65 mm. The protective layer is formed of carbon.

[0590] On the protective layer of the magnetic recording medium, which has formed layers up to the protective layer, the lubricating layer forming solutions of Examples 1-26 and Comparative Examples 1-3 were respectively applied by an immersion method. The immersion method was performed at an immersion speed of 10 mm / s, an immersion time of 30 seconds, and a pull-out speed of 1.2 mm / s.

[0591] Then, the magnetic recording medium coated with the lubricant layer forming solution is placed in a constant temperature bath at 120°C and heated for 10 minutes to remove the solvent from the lubricant layer forming solution, thereby forming a lubricant layer on the protective layer and obtaining the magnetic recording medium.

[0592] (Film thickness measurement)

[0593] The film thickness of the lubricating layer of the magnetic recording media of Examples 1-26 and Comparative Examples 1-3 obtained by such operation was measured using FT-IR (trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific). The results are shown in Table 4.

[0594] Next, the magnetic recording media of Examples 1-26 and Comparative Examples 1-3 were subjected to the following abrasion resistance tests.

[0595] (Abrasion resistance test)

[0596] Using a pin-disc type tribometer, an alumina ball with a diameter of 2 mm, acting as the contact element, was slid across the lubricating layer of a magnetic recording medium under a load of 40 gf and a sliding speed of 0.25 m / s. The coefficient of friction of the lubricating layer surface was measured. Furthermore, the sliding time until the coefficient of friction of the lubricating layer surface increased sharply (the coefficient of friction increase time) was measured. The coefficient of friction increase time was measured four times for each lubricating layer of each magnetic recording medium, and the average value (in hours) was used as an indicator of the wear resistance of the lubricant coating.

[0597] The results of the friction coefficient increase time for magnetic recording media using the compounds of Examples 1-26 and Comparative Examples 1-3 are shown in Table 4. The evaluation of the friction coefficient increase time is as follows. It can be understood that a larger value for the friction coefficient increase time is a better result.

[0598] ◎(Excellent): Over 750 seconds

[0599] ○ (Good): 650 seconds or more but less than 750 seconds

[0600] Δ (Pass): 550 seconds or more but less than 650 seconds

[0601] × (Failure): Less than 550 seconds

[0602] Furthermore, the time until the coefficient of friction increases sharply can be used as an indicator of the wear resistance of the lubricating layer for the following reasons. Since the lubricating layer of a magnetic recording medium wears down through the use of the medium, if the lubricating layer disappears due to wear, the contact element comes into direct contact with the protective layer, and the coefficient of friction increases sharply. Therefore, the time until this coefficient of friction increases sharply can be considered relevant to friction tests.

[0603] (Shedding Characteristics Test)

[0604] A magnetic recording medium was mounted on a spin mount and rotated at 10,000 rpm for 72 hours at 80°C. Before and after this operation, the film thickness of the lubricant layer at a radius of 20 mm from the center of the magnetic recording medium was measured using FT-IR, and the reduction rate of the lubricant layer thickness was calculated. The shedding characteristics were evaluated using the calculated film thickness reduction rate according to the evaluation criteria shown below. The results are shown in Table 4.

[0605] Evaluation criteria for shedding characteristics

[0606] ◎(Excellent): Film thickness reduction rate less than 2%

[0607] 〇 (Good): Film thickness reduction rate exceeding 2% but less than 3%

[0608] Δ (Pass): Film thickness reduction rate exceeding 3% but below 9%

[0609] × (Non-compliant): Film thickness reduction rate exceeds 9%

[0610] (Overall Evaluation)

[0611] Based on the results of abrasion resistance and shedding characteristics tests, a comprehensive evaluation was conducted using the following criteria.

[0612] ◎(Excellent): Both the abrasion resistance test and the shedding characteristic test are rated ◎.

[0613] ○ (Good): The evaluation of abrasion resistance test and shedding characteristic test is ◎ or ○, and any evaluation of abrasion resistance test and shedding characteristic test is ○.

[0614] × (Unacceptable): Does not meet the above standards of ◎ (Excellent) and ○ (Good).

[0615] As shown in Table 4, the magnetic recording media of Examples 1-26 exhibited longer sliding time until the coefficient of friction increased sharply, and better wear resistance compared to the magnetic recording media of Comparative Examples 1-3. Furthermore, the magnetic recording media of Examples 1-26 also showed better shedding characteristics (film thickness reduction rate) compared to the magnetic recording media of Comparative Examples 1-3.

[0616] This is presumed to be because the lubricating layer of the magnetic recording media in Examples 1-26 includes R in formula (1). 2 and R 4 At least one of them contains more than one secondary amine structure, and R 1 -R 2 -and-R 4 -R 5 At least one of the compounds contains one or more cyano groups.

[0617] Furthermore, the overall evaluation result of the magnetic recording media used in Examples 1-3, 10-17, 21, and 23-26 of compounds (A)-(C), (J)-(Q), (U), and (W)-(Z) was ◎ (Excellent), which is good. The molecules of compounds (A)-(C), (J)-(Q), (U), and (W)-(Z) contain 2 or more secondary amine structures (-NH-), 3 or fewer hydroxyl groups, 3 or fewer cyano groups, and the total number of secondary amine structures, hydroxyl groups, and cyano groups is 8 or fewer.

[0618] Industry availability

[0619] By using a lubricant for magnetic recording media containing the fluorinated ether compound of the present invention, a lubricating layer with excellent wear resistance and shedding resistance can be formed even when the thickness is thin.

[0620] That is, according to the present invention, a fluorinated ether compound can be provided that is capable of forming a lubricating layer with excellent wear resistance and shedding resistance even when the thickness is thin, making it suitable as a lubricant for magnetic recording media.

[0621] Explanation of symbols

[0622] 10. Magnetic Recording Media

[0623] 11···Substrate

[0624] 12··· Adhesion layer

[0625] 13··· Soft magnetic layer

[0626] 14···First basal layer

[0627] 15···Second basal layer

[0628] 16···Magnetic layer

[0629] 17··· Protective Layer

[0630] 18. Lubricating layer.

Claims

1. A fluorinated ether compound, characterized in that, It is represented by the following formula (1), R 1 -R 2 -O-CH2-R 3 -CH2-O-R 4 -R 5 (1) In equation (1), R 3 It is a perfluoropolyether chain, and is any one of the following formulas (6) to (10); R 1 and R 5 Each is independently a terminal group composed of any of the following: an alkyl group that may have substituents, or a hydrocarbon group having a double or triple bond; R 2 and R 4 Each is a divalent linker containing one or more heteroatoms, has one or more polar groups, and is associated with R. 1 and R 5 The terminal part of the bonding side is a heteroatom; R 2 and R 4 At least one of them contains one or more secondary amine structures; R 1 -R 2 -and-R 4 -R 5 At least one of them has one or more cyano groups. The alkyl group that may have substituents is an alkyl group having 1 to 8 carbon atoms. The substituents in the alkyl group that may have substituents are halogroups, alkoxy groups, hydroxy groups, or cyano groups. The hydrocarbon group having double or triple bonds is selected from phenyl, methoxyphenyl, fluorophenyl, naphthyl, phenethyl, methoxyphenethyl, fluorophenethyl, benzyl, methoxybenzyl, naphthylmethyl, methoxynaphthyl, pyrrolyl, pyrazolyl, methylpyrazolylmethyl, imidazolyl, furanyl, furfural, etc. azole group, iso Azolyl, thiophene, thiopheneylethyl, thiazolyl, methylthiazolylethyl, isothiazolyl, pyridyl, pyrimidinyl, pyrazinyl, dihydroindolyl, benzofuranyl, benzothiophene, benzimidazolyl, benzo[] Azolyl, benzothiazolyl, benzopyrazole, benzisocyanate Azolyl, benzisothiazolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinyl, phthalazinyl, cinolinyl, vinyl, allyl, butenyl, 1-propynyl, propynyl (i.e., 2-propynyl), butynyl, methylbutynyl, penynyl, methylpentynyl, and hexynyl; In equation (1), -R 2 -O- is represented by the following formula (2), -OR 4 - Represented by the following formula (3), -[A] a [B] d -O- (2) -O-[C] g [D] j - (3) In equation (2), [A] is represented by equation (4-1) below, and [B] is represented by equation (4-2) below; the order of [A] and [B] in equation (2) can be interchanged; a is an integer from 0 to 3, d is an integer from 0 to 3, and at least one of a and d is 1 or more; the end -CH2- on the opposite side of X in equation (4-1) or the end -CH2- on the opposite side of X in equation (4-2) combines with -O- in equation (2); In equation (3), [C] is represented by equation (5-1) below, and [D] is represented by equation (5-2) below; the order of [C] and [D] in equation (3) can be interchanged; g is an integer from 0 to 3, j is an integer from 0 to 3, and at least one of g and j is 1 or more; the end -CH2- on the opposite side of X in equation (5-1) or the end -CH2- on the opposite side of X in equation (5-2) combines with -O- in equation (3); In equation (4-1), b and c are integers from 0 to 4; in equation (4-2), e and f are integers from 0 to 4; in equation (5-1), h and i are integers from 0 to 4; in equation (5-2), k and l are integers from 0 to 4; in equations (4-1), (4-2), (5-1), and (5-2), X is 0 or NH; in equations (4-1), (4-2), (5-1), and (5-2), more than one of X is NH. -CF2O-(CF2CF2O) m -(CF2O) n -CF2- (6) In equation (6), m and n represent the average degree of polymerization, each ranging from 0.1 to 30. -CF2O-(CF2CF2O) w -CF2- (7) In equation (7), w represents the average degree of polymerization, ranging from 0.1 to 30. -CF2CF2O-(CF2CF2CF2O) x -CF2CF2- (8) In equation (8), x represents the average degree of polymerization, ranging from 0.1 to 30. -CF2CF2CF2O-(CF2CF2CF2CF2O) y -CF2CF2CF2- (9) In equation (9), y represents the average degree of polymerization, ranging from 0.1 to 30. -CF(CF3)-(OCF(CF3)CF2) z -OCF(CF3)- (10) In equation (10), z represents the average degree of polymerization, which ranges from 0.1 to 30.

2. The fluorinated ether compound according to claim 1, wherein the number of secondary amine structures contained in the molecule is 2 or more.

3. The fluorinated ether compound according to claim 1, wherein the number of hydroxyl groups contained in the molecule is 3 or less.

4. The fluorinated ether compound according to claim 1, wherein the number of cyano groups contained in the molecule is 3 or less.

5. The fluorinated ether compound according to claim 1, wherein the total number of secondary amine structures, hydroxyl groups, and cyano groups contained in the molecule is 8 or less.

6. The fluorinated ether compound according to claim 1, wherein the molecule contains 2 or more secondary amine structures, 3 or fewer hydroxyl groups, 3 or fewer cyano groups, and the total number of secondary amine structures, hydroxyl groups, and cyano groups is 8 or fewer.

7. The fluorinated ether compound according to claim 1, wherein -R in formula (1) 2 -O- can be any one of the following formulas (11-1) to (11-12), 。 8. The fluorinated ether compound according to claim 1, wherein the alkyl group that may have substituents is an alkyl group having a hydroxyl or a cyano group.

9. The fluorinated ether compound according to claim 1, wherein the compound represented by formula (1) is any one of the compounds represented by formulas (A), (J), (P), (Q), and (U) below. In formula (A), ma and na represent the average degree of polymerization, where ma represents 1 to 30 and na represents 0.1 to 30. In formula (J), mj and nj represent the average degree of polymerization, where mj represents 1 to 30 and nj represents 0.1 to 30. In formula (P), mp and np represent the average degree of polymerization, where mp represents 1 to 30 and np represents 0.1 to 30. In equation (Q), mq and nq represent the average degree of polymerization, where mq represents 1 to 30 and nq represents 0.1 to 30. In formula (U), mu and nu represent the average degree of polymerization, where mu represents 1 to 30 and nu represents 0.1 to 30.

10. The fluorinated ether compound according to claim 1, wherein the number average molecular weight is in the range of 500 to 10,000.

11. A lubricant for magnetic recording media, characterized in that, It includes the fluorinated ether compound of claim 1.

12. A magnetic recording medium, characterized in that, It is a magnetic recording medium on which at least a magnetic layer, a protective layer, and a lubricating layer are sequentially disposed on a substrate. The lubricating layer comprises the fluorinated ether compound of claim 1.

13. The magnetic recording medium according to claim 12, wherein the average film thickness of the lubricating layer is 0.5 nm to 2.0 nm.

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