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

Abstract

A fluorine-containing ether compound represented by the following formula. R 1 -[B]-[A]-O-CH2-R 2 -CH2-O-[C]-[D]-R 3 (R 1 is an organic group having 7 to 18 carbon atoms which is a group in which a carbonyl carbon atom or a nitrogen atom of an amide bond is directly bonded to an aromatic hydrocarbon; R 2 is a perfluoropolyether chain; R 3 is formula (2); X 1 is a hydrogen atom or an organic group having 7 to 18 carbon atoms which is a group in which a carbonyl carbon atom or a nitrogen atom of an amide bond is directly bonded to an aromatic hydrocarbon; [A] is formula (3-1); [B] is formula (3-2); [C] is formula (4-1); [D] is formula (4-2); the number of hydroxyl groups in formula (1) is 3 or more.

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 Japan Patent Application No. 2021-143420, filed on September 2, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] In recent years, the amount of information processed via networks has increased dramatically. Therefore, the development of recording media has attracted much attention. In particular, magnetic recording media, as a type of recording medium, is expected to be a receiver of increasing data volumes due to its low cost and ability to store large amounts of data.

[0004] As a magnetic recording medium, there is a type of magnetic recording medium in which a magnetic layer (magnetic recording layer) is formed on a substrate, and a protective layer such as carbon is formed on the magnetic layer. The protective layer protects the information recorded in the magnetic layer and improves the sliding performance of the magnetic head. However, simply placing a protective layer on the magnetic layer is not enough to achieve sufficient durability of the magnetic recording medium. Therefore, a lubricant is usually coated on the surface of the protective layer to form a lubricating layer.

[0005] For the lubricating layer disposed on the outermost surface of the magnetic recording medium, various properties are required, such as chemical resistance (to prevent contamination by siloxanes, etc.), wear resistance, corrosion resistance, head buoyancy stability, heat / decomposition resistance, and long-term stability of film thickness.

[0006] As a lubricant for magnetic recording media used in the lubrication layer (hereinafter sometimes abbreviated as "lubricant"), fluorinated ether compounds having perfluoropolyether (hereinafter sometimes abbreviated as "PFPE") chains have been proposed (see, for example, Patent Documents 1-5).

[0007] Patent Documents 1 and 2 disclose a fluorinated ether compound capable of forming a lubricating layer with excellent chemical resistance and wear resistance even when the layer is thin. Patent Document 1 discloses a fluorinated ether compound having an aryl and a hydroxyl group at one end of a PFPE chain and two or three hydroxyl groups at the other end. Patent Document 2 discloses a fluorinated ether compound having a chain-like organic group with an amide bond at one or both ends of a PFPE chain.

[0008] Patent Document 3 discloses a lubricant containing a fluorinated polyether compound, which maintains excellent resistance to degradation and reduces the film thickness per molecule. Patent Document 3 discloses a fluorinated polyether compound wherein a phenyl group substituted with an alkoxy, amino, or amide group is configured at one end of the PFPE chain, and a specific terminal group containing a hydroxyl group is configured at the other end.

[0009] Patent Document 4 discloses a disk having a lubricating layer and exhibiting excellent LUL (Load Unload) durability and alumina resistance (inhibiting the decomposition of lubricant caused by alumina). Patent Document 4 discloses a compound contained in the lubricating layer, which has a PFPE backbone and aromatic and hydroxyl groups at the ends of the molecule, with the aromatic and hydroxyl groups bonded to different carbon atoms.

[0010] Patent Document 5 discloses a lubricant containing a fluoropolyether compound, which does not undergo thermal decomposition even under high heat, does not transfer or adhere to the magnetic head, and exhibits high heat resistance. Patent Document 5 discloses a fluoropolyether compound having a specific linking group containing a hydroxyl group and a phenyl group substituted with an alkoxy, amino, or amide group at both ends of the PFPE chain.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: International Publication No. 2017 / 154403

[0014] Patent Document 2: International Publication No. 2019 / 039265

[0015] Patent Document 3: Japanese Patent No. 5909837

[0016] Patent Document 4: Japanese Patent No. 5465454

[0017] Patent Document 5: Japanese Patent No. 6040455 Summary of the Invention

[0018] The problem that the invention aims to solve

[0019] To increase the capacity of magnetic recording playback devices, the development of magnetic recording media suitable for high recording density is underway. In recent years, to improve the recording density of magnetic recording media, it is necessary to reduce the magnetic pitch (the distance between the magnetic head and the magnetic layer of the magnetic recording medium (levitation height)) and increase the rotation speed of the magnetic recording medium.

[0020] However, if the head's levitation height is reduced, lubricant can easily adhere to the head as foreign matter (stains), a phenomenon known as sticking. If sticking occurs, the head's levitation becomes unstable, raising concerns about potential contact between the head and the magnetic recording medium.

[0021] Furthermore, increasing the rotation speed of the magnetic recording medium can cause spin-off, which can easily reduce the thickness of the lubricant layer. Spin-off occurs when the lubricant is dispersed or evaporated due to the centrifugal force and / or heat generated by the rotation of the magnetic recording medium. If the thickness of the lubricant layer is reduced due to spin-off, the required chemical resistance, wear resistance, corrosion resistance, and head levitation stability of the lubricant layer cannot be maintained.

[0022] In addition, to improve the floating stability of the magnetic head, besides suppressing adhesion and detachment, it is important that the lubricating layer has good adhesion to the protective layer and that the lubricating layer disposed on the outermost surface of the magnetic recording medium has good smoothness.

[0023] The present invention is made in view of the above circumstances, and its object is to provide a fluorinated ether compound that can form a lubricating layer that is not prone to adhesion and peeling and provides good adhesion and smoothness to the protective layer, and the fluorinated ether compound can be suitably used as a material for a lubricant for magnetic recording media.

[0024] In addition, the present invention aims to provide a lubricant for magnetic recording media, which contains the fluorinated ether compound of the present invention, wherein the lubricant for magnetic recording media can form a lubricating layer that is not prone to adhesion and peeling and provides good adhesion and smoothness to the protective layer.

[0025] In addition, the present invention aims to provide a magnetic recording medium having a lubricating layer comprising the fluorinated ether compound of the present invention, and exhibiting excellent levitation stability of the magnetic head.

[0026] Methods for solving problems

[0027] The inventors of this application have conducted repeated and in-depth research in order to solve the above-mentioned problems.

[0028] It was found that specific fluorinated ether compounds can be used, wherein the fluorinated ether compound has terminal groups at one or two ends of the perfluoropolyether chain, consisting of a carbonyl carbon atom or nitrogen atom containing an amide bond directly bonded to an aromatic hydrocarbon, and has three or more hydroxyl groups. Furthermore, it was confirmed that by using a lubricant for magnetic recording media containing such a fluorinated ether compound, a lubricating layer that is not prone to adhesion or detachment and provides good adhesion and smoothness to the protective layer can be formed, thus leading to the present invention.

[0029] The present invention includes the following methods.

[0030] The first aspect of the present invention provides the following fluorinated ether compound.

[0031] [1] A fluorinated ether compound, characterized in that it is represented by the following formula (1).

[0032] R 1 -[B]-[A]-O-CH2-R 2 -CH2-O-[C]-[D]-R 3 (1)

[0033] (In equation (1), R) 1 An organic group having 7 to 18 carbon atoms, consisting of a carbonyl carbon atom or nitrogen atom containing an amide bond directly bonded to an aromatic hydrocarbon; R 2 It is a perfluoropolyether chain; R 3 It is represented by the following formula (2); in formula (2), a represents an integer from 2 to 6, and b represents 0 or 1; X 1 It is an organic group with 7 to 18 carbon atoms or a hydrogen atom, wherein the organic group with 7 to 18 carbon atoms includes a group formed by the direct bonding of a carbonyl carbon atom or a nitrogen atom with an amide bond and an aromatic hydrocarbon; in formula (1), [A] is represented by the following formula (3-1); in formula (3-1), c is an integer from 0 to 3; in formula (1), [B] is represented by the following formula (3-2); in formula (3-2), d is an integer from 0 to 3, and e is an integer from 2 to 5; wherein, c in formula (3-1) and formula (3-2) The sum of d in the formula is 1 to 3; [A] and [B] in formula (1) can be interchanged; [C] in formula (1) is represented by the following formula (4-1); f in formula (4-1) is an integer from 0 to 3; [D] in formula (1) is represented by the following formula (4-2); g in formula (4-2) is an integer from 0 to 3, and h is an integer from 2 to 5; where the sum of f in formula (4-1) and g in formula (4-2) is 1 to 3; [C] and [D] in formula (1) can be interchanged; [C] is directly bonded to R 3 In the case of R 3 It is not a hydrogen atom; the number of hydroxyl groups in formula (1) is 3 or more, R 1 and R 3 The number of hydroxyl groups in each hydroxyl group is either 0 or 1.

[0034]

[0035] The fluorinated ether compound of the first aspect of the present invention preferably has the features described in [2] to [8] below. It is also preferable that two or more of the features described in [2] to [8] below are combined arbitrarily.

[0036] [2] According to the fluorinated ether compound described in [1], R in formula (1) 1 It can be any structure represented by the following equations (5-1) to (5-5).

[0037]

[0038] (In equations (5-1) to (5-3), X)2 It refers to one or more groups represented by formula (6-1) or (6-2).

[0039] (In equations (5-4) and (5-5), Y) 5 It is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; L represents an integer from 1 to 6; Z is any one or more selected from hydrogen atoms, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, and groups represented by formula (6-1) or (6-2).

[0040]

[0041] (In equation (6-1), Y) 1 and Y 2 Each is independently composed of hydrogen atoms, alkyl groups having 1 to 7 carbon atoms, and Y. 1 With Y 2 Any of the ring structures formed by mutual bonding; the total number of carbon atoms contained in formula (6-1) is 1 to 8.

[0042] (In equation (6-2), Y) 3 Y is an alkyl group having 1 to 7 carbon atoms. 4 It can be a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; it can also be Y. 3 With Y 4 A ring structure formed by bonds between atoms; the total number of carbon atoms in formula (6-2) is 2 to 8.

[0043] [3] According to the fluorinated ether compound described in [1] or [2], R in formula (1) 1 -[B]-[A]-and-[C]-[D]-R 3 They are the same.

[0044] [4] According to the fluorinated ether compound described in [1] or [2], X in formula (2) 1 It is a hydrogen atom.

[0045] [5] According to the fluorinated ether compound described in [1] or [2], the -[C]-[D]-R in formula (1) 3 It can be any one of the following formulas (7-1) to (7-3).

[0046]

[0047] (In equation (7-1), i represents 1 or 2, and j represents an integer from 1 to 5.)

[0048] (In equation (7-2), k represents an integer from 2 to 5, t represents 0 or 1, and p represents an integer from 1 to 5.)

[0049] (In equation (7-3), q represents 0 or 1, r represents an integer from 1 to 5, and s represents an integer from 1 to 4.)

[0050] [6] The fluorinated ether compound according to any one of [1] to [5], wherein R in formula (1) 2 It is represented by the following formula (8-1).

[0051] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(8-1)

[0052] (In Equation (8-1), w2, w3, w4, and w5 represent the average degree of polymerization, each independently representing 0 to 30; excluding the case where all of w2, w3, w4, and w5 are simultaneously 0; w1 and w6 represent the average quantity of CF2, each independently representing 1 to 3; the order of repeating units in Equation (8-1) is not particularly restricted.)

[0053] [7] The fluorinated ether compound according to any one of [1] to [6], wherein R in formula (1) 2 It can be any one of the following formulas (8-2) to (8-5).

[0054] -CF₂O-(CF₂CF₂O) u -(CF2O) v -CF2- (8-2)

[0055] (In equation (8-2), u and v represent the average degree of polymerization, each ranging from 0 to 30; where u or v is 0.1 or higher.)

[0056] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 - (8-3)

[0057] (In equation (8-3), w8 and w9 represent the average degree of polymerization, each independently representing 0.1 to 30; w7 and w10 represent the average amount of CF2, each independently representing 1 to 2.)

[0058] -CF2CF2O-(CF2CF2CF2O) x -CF2CF2- (8-4)

[0059] (In equation (8-4), x represents the average degree of polymerization, and ranges from 0.1 to 30.)

[0060] -CF2CF2CF2O-(CF2CF2CF2CF2O) y -CF2CF2CF2- (8-5)

[0061] (In equation (8-5), y represents the average degree of polymerization, and is expressed as 0.1 to 30.)

[0062] [8] The fluorinated ether compound according to any one of [1] to [7] has a number-average molecular weight in the range of 500 to 10,000.

[0063] A second aspect of the present invention provides a lubricant for magnetic recording media.

[0064] [9] A lubricant for magnetic recording media, characterized in that it comprises any one of [1] to [8] a fluorinated ether compound.

[0065] The third aspect of the present invention provides the following magnetic recording medium.

[0066]

[10] A magnetic recording medium, characterized in that it is a magnetic recording medium having at least a magnetic layer, a protective layer and a lubricating layer sequentially disposed on a substrate, wherein the lubricating layer comprises any one of [1] to [8] a fluorinated ether compound.

[0067] The third-party magnetic recording medium of the present invention preferably has the features described in

[11] .

[0068]

[11] According to the magnetic recording medium of

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

[0069] Invention Effects

[0070] The fluorinated ether compound of the present invention is the compound represented by the above formula (1), and is suitable as a material for a lubricant for magnetic recording media.

[0071] The lubricant for magnetic recording media of the present invention comprises the fluorinated ether compound of the present invention. Therefore, it is possible to form a lubricating layer that is not prone to adhesion and peeling and provides good adhesion and smoothness to the protective layer.

[0072] The magnetic recording medium of this invention has a lubricating layer that is resistant to adhesion and detachment and provides excellent adhesion and smoothness to the protective layer, resulting in superior head levitation stability. Therefore, the magnetic recording medium of this invention enables the reduction of magnetic pitch and the increase of rotational speed, which helps to improve recording density. Attached Figure Description

[0073] [ Figure 1 This is a schematic cross-sectional view illustrating a preferred embodiment of the magnetic recording medium of the present invention. Detailed Implementation

[0074] To address the aforementioned issues, the inventors of this application focused on the relationship between the molecular structure of the fluorinated ether compound contained in the lubricating layer and the protective layer, and conducted repeated in-depth studies as shown below.

[0075] Previously, fluorinated ether compounds with hydroxyl groups in their molecules were used as lubricants to obtain a lubricating layer with good adhesion to the protective layer. However, even with fluorinated ether compounds having multiple hydroxyl groups in their molecules, the lubricating layer formed using conventional lubricants sometimes failed to achieve sufficient adhesion to the protective layer.

[0076] If the adhesion between the lubricating layer and the protective layer is insufficient, the lubricating layer becomes loose, making it difficult to obtain a lubricating layer with uniform thickness and good smoothness. This is presumably because the fluorinated ether compounds in the lubricating layer locally aggregate, or some of the fluorinated ether compound molecules float from the surface of the protective layer, forming unevenness on the surface of the lubricating layer. Furthermore, the localized aggregation of the fluorinated ether compounds and the floating of fluorinated ether compound molecules from the surface of the protective layer are the causes of adhesion and detachment.

[0077] Furthermore, the inventors of this application have learned through in-depth research that if there are hydroxyl groups in the fluorinated ether compound contained in the lubricating layer that have not participated in the adsorption with the protective layer, the adhesion between the lubricating layer and the protective layer cannot be fully obtained, the surface of the lubricating layer becomes more uneven, and adhesion and detachment are more likely to occur.

[0078] For example, in fluorinated ether compounds with a vicinal diol structure (-CH(OH)-CH(OH)-) formed by carbon atoms bonded to each other with hydroxyl groups, the two adjacent hydroxyl groups in the vicinal diol structure cannot be simultaneously adsorbed onto the protective layer due to steric factors. Therefore, if one of the two hydroxyl groups adsorbs onto the protective layer, the other hydroxyl group cannot participate in the adsorption of the protective layer and will float off the surface of the protective layer. As a result, the adhesion between the lubricating layer and the protective layer of the fluorinated ether compound containing the vicinal diol structure tends to become insufficient, and adhesion and detachment are likely to occur. Furthermore, the hydroxyl groups in the fluorinated ether compound that float off the surface of the protective layer can easily induce contamination of the lubricating layer. Therefore, from the viewpoint of the floating stability of the magnetic head and chemical resistance, a lubricating layer containing a vicinal diol structure is not preferred.

[0079] Therefore, in order to improve the adhesion of the lubricating layer to the protective layer, the inventors of this application have repeatedly studied the molecular structure of fluorinated ether compounds used as lubricating layers. As a result, it was discovered that the following fluorinated ether compounds can be prepared, wherein specific linking groups with secondary hydroxyl groups are respectively configured at both ends of the PFPE chain via methylene (-CH2-), and an organic group containing an amide bond formed by the direct bonding of a carbonyl carbon atom or nitrogen atom to an aromatic hydrocarbon is configured at at least one end, thus leading to the present invention.

[0080] The following provides a detailed description of examples of the fluorinated ether compounds, lubricants for magnetic recording media, and magnetic recording media of the present invention. It should be noted that the present invention is not limited to the embodiments shown below. The present invention may include additions, omissions, substitutions, and modifications to quantities, amounts, ratios, materials, and compositions without departing from the spirit of the invention.

[0081] [Fluoroether compounds]

[0082] The fluorinated ether compound in this embodiment is represented by the following formula (1).

[0083] R 1 -[B]-[A]-O-CH2-R 2 -CH2-O-[C]-[D]-R 3 (1)

[0084] (In equation (1), R) 1 An organic group having 7 to 18 carbon atoms, consisting of a carbonyl carbon atom or nitrogen atom containing an amide bond directly bonded to an aromatic hydrocarbon; R 2 It is a perfluoropolyether chain; R 3 It is represented by the following formula (2); in formula (2), a represents an integer from 2 to 6, and b represents 0 or 1; X 1It is an organic group with 7 to 18 carbon atoms or a hydrogen atom or a carbon atom with 7 to 18 carbon atoms, wherein the organic group with 7 to 18 carbon atoms includes a group formed by the direct bonding of a carbonyl carbon atom or a nitrogen atom with an amide bond and an aromatic hydrocarbon; in formula (1), [A] is represented by the following formula (3-1); c in formula (3-1) is an integer from 0 to 3; in formula (1), [B] is represented by the following formula (3-2); d in formula (3-2) is an integer from 0 to 3, and e is an integer from 2 to 5; wherein the sum of c in formula (3-1) and d in formula (3-2) is 1 to 3; [A] and [B] in formula (1) can be interchanged; in formula (1), [C] is represented by the following formula (4-1); f in formula (4-1) is an integer from 0 to 3. In equation (1), [D] is represented by the following equation (4-2); in equation (4-2), g is an integer from 0 to 3, and h is an integer from 2 to 5; wherein, the sum of f in equation (4-1) and g in equation (4-2) is 1 to 3; [C] and [D] in equation (1] can be interchanged; [C] is directly bonded to R 3 In the case of R 3 It is not a hydrogen atom; the number of hydroxyl groups in formula (1) is 3 or more, R 1 and R 3 The number of hydroxyl groups in each hydroxyl group is either 0 or 1.

[0085]

[0086] (R 2 (representing the PFPE chain)

[0087] In the fluorinated ether compound of this embodiment represented by formula (1), R 2 It consists of perfluoropolyether (PFPE) chains. When a lubricant containing a fluorinated ether compound is coated onto a protective layer to form a lubricating layer, the PFPE chains coat the surface of the protective layer and impart lubrication, thereby reducing the friction between the magnetic head and the protective layer. 2 The PFPE chain indicated is not particularly limited and can be appropriately selected according to the performance requirements of the lubricant.

[0088] As R 2 Examples of PFPE chains include, for example, perfluoromethylene oxidase polymers, perfluoroethyl oxidase polymers, perfluoropropyl oxidase n-propylene polymers, perfluoroisopropyl oxidase isopropyl oxidase polymers, perfluorobutyl oxidase n-butyl polymers, and PFPE chains formed from their copolymers.

[0089] R in equation (1) 2 For example, a structure represented by the following formula (8-1) is preferred, which is a polymer or copolymer derived from perfluoroalkylene oxides.

[0090] -(CF2) w1 -O-(CF2O)w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(8-1)

[0091] (In Equation (8-1), w2, w3, w4, and w5 represent the average degree of polymerization, each independently representing 0 to 30; excluding the case where all of w2, w3, w4, and w5 are simultaneously 0; w1 and w6 represent the average quantity of CF2, each independently representing 1 to 3; the order of repeating units in Equation (8-1) is not particularly restricted.)

[0092] In equation (8-1), w2, w3, w4, and w5 represent the average degree of polymerization, each independently representing 0 to 30, preferably 0 to 20, and more preferably 0 to 15. For example, w2, w3, w4, and w5 can each independently be 1 to 28, 2 to 25, 3 to 17, 5 to 10, etc.

[0093] In equation (8-1), w1 and w6 are average values ​​representing the number of CF2, each independently representing 1 to 3. w1 and w6 can be determined based on the structure of the repeating units arranged at the ends of the chain-like structure in the PFPE chain represented by equation (8-1).

[0094] In equation (8-1), (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) are repeating units. There is no particular restriction on the order of the repeating units in equation (8-1). Furthermore, there is no particular restriction on the number of types of repeating units in equation (8-1).

[0095] Specifically, R in equation (1) 2 Preferably, any one of the following formulas (8-2) to (8-5) is used.

[0096] -CF₂O-(CF₂CF₂O) u -(CF2O) v -CF2- (8-2)

[0097] (In equation (8-2), u and v represent the average degree of polymerization, each ranging from 0 to 30; where u or v is 0.1 or higher.)

[0098] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 - (8-3)

[0099] (In equation (8-3), w8 and w9 represent the average degree of polymerization, each independently representing 0.1 to 30; w7 and w10 represent the average amount of CF2, each independently representing 1 to 2.)

[0100] -CF2CF2O-(CF2CF2CF2O) x -CF2CF2- (8-4)

[0101] (In equation (8-4), x represents the average degree of polymerization, and ranges from 0.1 to 30.)

[0102] -CF2CF2CF2O-(CF2CF2CF2CF2O) y -CF2CF2CF2- (8-5)

[0103] (In equation (8-5), y represents the average degree of polymerization, and is expressed as 0.1 to 30.)

[0104] In Equation (8-2), the order of the repeating units (CF2CF2O) and (CF2O) is not particularly restricted. In Equation (8-2), the quantity u of (CF2CF2O) and the quantity v of (CF2O) can be the same or different. The PFPE chain represented by Equation (8-2) can be a polymer of (CF2CF2O) or a polymer of (CF2O). Furthermore, the PFPE chain represented by Equation (8-2) can include any of the following: random copolymers, block copolymers, and alternating copolymers formed from (CF2CF2O) and (CF2O).

[0105] In formula (8-2), u, representing the average degree of polymerization, is 0 to 30, preferably 1 to 20, and more preferably 2 to 15. In formula (8-2), v, representing the average degree of polymerization, is 0 to 30, preferably 0 to 20, and more preferably 0 to 15. v can also be 1 to 10, 2 to 5, etc. In formula (8-2), when v is 0, u is preferably 1 to 20. If u and v, representing the average degree of polymerization, are within the above ranges, it becomes a fluorinated ether compound that is easily wetted and spread on the protective layer, thus easily obtaining a lubricating layer with a uniform film thickness, and is therefore preferred.

[0106] In Equation (8-3), the order of the repeating units (CF2CF2CF2O) and (CF2CF2O) is not particularly restricted. In Equation (8-3), the number of (CF2CF2CF2O) units w8 and w9, representing the average degree of polymerization, can be the same or different. The PFPE chain represented by Equation (8-3) can contain any of the following: random copolymers, block copolymers, and alternating copolymers formed from (CF2CF2CF2O) and (CF2CF2O).

[0107] In formula (8-3), w8 and w9, representing the average degree of polymerization, are each independently 0.1 to 30, preferably 0.1 to 20, and more preferably 1 to 15. If w8 and w9, representing the average degree of polymerization, are within the above ranges, it becomes a fluorinated ether compound that is easily wetted and spread on the protective layer, thus easily obtaining a lubricating layer with a uniform film thickness, and is therefore preferred. In formula (8-3), w7 and w10 are average values ​​representing the amount of CF2, each independently representing 1 to 2. w7 and w10 can be determined based on the structure of the repeating units disposed at the ends of the chain-like structure in the PFPE chain represented by formula (8-3).

[0108] In formula (8-4), x, representing the average degree of polymerization, is 0.1 to 30. When x is 0.1 to 30, the number-average molecular weight of the fluorinated ether compound of this embodiment is easily within the preferred range. x is preferably 1 to 20, and more preferably 2 to 15.

[0109] In formula (8-5), y, representing the average degree of polymerization, is 0.1 to 30. When y is 0.1 to 30, the number-average molecular weight of the fluorinated ether compound of this embodiment is easily within the preferred range. y is preferably 1 to 20, and more preferably 2 to 15.

[0110] If R in equation (1) 2 If R is any one of formulas (8-2) to (8-5), it becomes a fluorinated ether compound that can produce a lubricating layer with good lubricity. Additionally, in formula (1), R... 2 When any of formulas (8-2) to (8-5) is used, the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) to the number of carbon atoms in the PFPE chain and the arrangement of oxygen atoms in the PFPE chain become appropriate. Therefore, a fluorinated ether compound with moderate hardness is obtained. Consequently, the fluorinated ether compound coated onto the protective layer is less likely to agglomerate on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage. Furthermore, if R in formula (1) 2 If the fluorinated ether compound is any one of formulas (8-2) to (8-5), then the fluorinated ether compound is readily synthesized and is therefore preferred. Especially in R... 2 In the case of formula (8-2) or formula (8-4), the raw materials are readily available, and therefore are preferred.

[0111] (-[B]-[A]- represents the linking group)

[0112] In the fluorinated ether compound of this embodiment represented by formula (1), -[B]-[A]- is a divalent linking group. [A] and [B] in formula (1) are interchangeable. [A] is represented by formula (3-1) above, and [B] is represented by formula (3-2) above. c in formula (3-1) and d in formula (3-2) are integers from 0 to 3.

[0113] For the linking group represented by -[B]-[A]-, from the viewpoint of ease of obtaining raw materials and synthesis, the combination of c in formula (3-1) being 1 and d in formula (3-2) being 0, or the combination of c being 0 and d being 1, is preferred.

[0114] Furthermore, for the linking group represented by -[B]-[A]-, from the viewpoint of adhesion to the protective layer, the combination of c being 2 and d being 0, or the combination of c being 1 and d being 1, is preferred. In the case of c being 2 and d being 0, in the fluorinated ether compound, the orientation of the two hydroxyl groups in formula (3-1) is stereoscopically the same relative to the extension direction of the PFPE chain, and it can be observed that the two hydroxyl groups in formula (3-1) tend to readily adsorb onto the protective layer. Additionally, when c and d are 1 and the bonding order of [A] and [B] is from R... 1 When the side is -[A]-[B]-, the hydroxyl groups in the linking group represented by -[A]-[B]- are further apart than each other. Therefore, the intramolecular hydrogen bonds of the fluorinated ether compound represented by formula (1) can be reduced, and its adhesion to the protective layer can be improved.

[0115] In equation (3-2), e is an integer from 2 to 5. Since e is greater than 2, the bonding order of [A] and [B] follows from R. 1 When the side orientation is -[A]-[B]-, the intramolecular hydrogen bonds formed between the hydroxyl groups contained in [B] and the intramolecular hydrogen bonds formed between the hydroxyl groups contained in [B] and the hydroxyl groups contained in [A] adjacent to [B] can be reduced. Since e is 5 or less, the proportion of fluorine atoms in the fluorinated ether compound molecule is reduced, which can suppress the increase of the overall surface free energy of the molecule. Generally, fluorinated ether compounds with a high overall surface free energy of the molecule are prone to inducing contamination of the lubricating layer containing it. Therefore, from the viewpoint of the chemical resistance of the lubricating layer, fluorinated ether compounds with a low overall surface free energy of the molecule are preferred. When d is an integer from 1 to 3, e is preferably an integer from 2 to 4, and most preferably 2.

[0116] In the linking group represented by -[B]-[A]-, the sum of c in formula (3-1) and d in formula (3-2) is 1 to 3. Since the sum of c and d is 1 or more, a lubricating layer with excellent adhesion to the protective layer can be formed by utilizing the adsorption force of the hydroxyl group of the linking group represented by -[B]-[A]- on the protective layer. Since the sum of c and d is 3 or less, the proportion of fluorine atoms in the fluorinated ether compound molecule can be sufficiently ensured. The sum of c and d is preferably 1 or 2, depending on -[C]-[D]-R 3 The number of hydroxyl groups contained therein is appropriately determined.

[0117] (R 1 (representing the terminal group)

[0118] In equation (1), R 1 The terminal group indicates that the number of hydroxyl groups is 0 or 1. R 1 An organic group having 7 to 18 carbon atoms, consisting of a carbonyl carbon atom or nitrogen atom containing an amide bond directly bonded to an aromatic hydrocarbon. R 1 In this process, either the carbonyl carbon atom or the nitrogen atom that forms the amide bond can be directly bonded to an aromatic hydrocarbon group.

[0119] Typically, it is known that amide bonds directly bonded to aromatic hydrocarbon groups form a coplanar shape with the aromatic hydrocarbon group, thus stabilizing it. Therefore, R in equation (1) 1 Because the amide bond forms a coplanar plane with the aromatic hydrocarbon group, it has a rigid structure with suppressed bond rotation. Therefore, it is speculated that R in equation (1) 1 It is easily adsorbed onto the protective layer. Therefore, in the lubricating layer containing the fluorinated ether compound of this embodiment, a portion of the fluorinated ether compound molecules are not easily lifted from the surface of the protective layer, thus forming a lubricating layer with good adhesion to the protective layer.

[0120] In contrast, the carbonyl carbon atom or nitrogen atom with an amide bond is not directly bonded to the aromatic hydrocarbon group, but the methylene (-CH2-) group, which acts as a linking group, is an organic group that lies between the carbonyl carbon atom or nitrogen atom of the amide bond and the aromatic hydrocarbon group, replacing R in formula (1). 1 In the case of terminal groups, lubricating layers containing fluorinated ether compounds become difficult to adsorb onto the protective layer. This is presumably because the terminal groups bend at the bonding sites composed of methylene groups, and the amide bonds and aromatic hydrocarbon groups do not form the same plane.

[0121] In addition, a chain-like organic group containing an amide bond is used to replace R in formula (1). 1 In the case of terminal groups, lubricating layers containing fluorinated ether compounds also become difficult to adsorb onto the protective layer. This is presumably because the terminal groups possess a high degree of freedom in the bonding of their chain-like organic groups, thus preventing the formation of R in formula (1). 1 That kind of planar structure.

[0122] R in equation (1) 1 The number of amide bonds contained in it is not particularly limited; it can be one or more. From the viewpoint of ease of synthesis of fluorinated ether compounds, R... 1 The number of amide bonds contained therein is preferably one. In R 1 In the case where multiple amide bonds are directly bonded to the carbonyl carbon atom or nitrogen atom of an aromatic hydrocarbon group, R1 The preferred number of amide bonds contained therein is 2.

[0123] From the perspective of the solubility of fluorinated ether compounds in solvents, R in formula (1) 1 The aromatic hydrocarbon group contained therein is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring. When the aromatic hydrocarbon group is a benzene ring or a naphthalene ring, it has good solubility in solvents compared to fluorinated ether compounds having polycyclic aromatic hydrocarbon groups formed by the fusion of three or more rings, thus making the coating of the lubricant containing it easier.

[0124] R in equation (1) 1 The total number of carbon atoms contained therein is 7 to 18, and in order to suppress the decrease in the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably 7 to 15, and more preferably 7 to 13.

[0125] In formula (1), considering the adhesion of the fluorinated ether compound to the protective layer, R 1 Preferably, any structure represented by formulas (5-1) to (5-5) below is preferred, considering the solubility of fluorinated ether compounds in solvents, R 1 More preferably, any structure represented by formula (5-1), formula (5-4), and formula (5-5) is preferred, considering that the amide bond and the aromatic hydrocarbon group can easily form a coplanar shape, R 1 The structure represented by formula (5-1) is particularly preferred.

[0126]

[0127] (In equations (5-1) to (5-3), X) 2 It refers to one or more groups represented by formula (6-1) or (6-2).

[0128] (In equations (5-4) and (5-5), Y) 5 It is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; L represents an integer from 1 to 6; Z is any one or more selected from hydrogen atoms, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, and groups represented by formula (6-1) or (6-2).

[0129]

[0130] (In equation (6-1), Y) 1 and Y 2 Each is independently composed of hydrogen atoms, alkyl groups having 1 to 7 carbon atoms, and Y. 1 With Y 2 Any of the ring structures formed by mutual bonding; the total number of carbon atoms contained in formula (6-1) is 1 to 8.

[0131] (In equation (6-2), Y) 3 Y is an alkyl group having 1 to 7 carbon atoms. 4 It can be a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; it can also be Y. 3 With Y 4 A ring structure formed by bonds between atoms; the total number of carbon atoms in formula (6-2) is 2 to 8.

[0132] In formulas (5-1), (5-4), and (5-5), the position of the substituents bonded to the benzene ring is not particularly limited. For example, in formula (5-1), X... 2 When there is only one Z, its positional relationship can be any relationship between adjacent, between, or in pairs. In addition, when there is only one Z in equations (5-4) and (5-5), its positional relationship can be any relationship between adjacent, between, or in pairs.

[0133] In formulas (5-2) and (5-3), the position of the substituents bonded to the naphthalene ring is not particularly limited, and all combinations can be selected.

[0134] In equation (6-1), Y 1 and Y 2 Each is independently composed of hydrogen atoms, alkyl groups having 1 to 7 carbon atoms, and Y. 1 With Y 2 Any one of the ring structures formed by bonding together.

[0135] Alkyl groups having 1 to 7 carbon atoms can be straight-chain or branched. Specifically, examples of alkyl groups having 1 to 7 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl and their structural isomers, n-hexyl and their structural isomers, and n-heptyl and their structural isomers.

[0136] From the perspective of steric hindrance when adsorbed onto the protective layer, Y 1 and / or Y 2 Preferably, it is selected from any one of hydrogen atom, methyl, ethyl, and n-propyl, more preferably Y. 1 and Y 2 At least one of them is a hydrogen atom, with Y being the most preferred. 1 and Y 2 Both of these are hydrogen atoms. If Y 1 and Y 2 If one of them is a hydrogen atom, then R 1 The -NH- groups contained therein adsorb onto the protective layer, thus becoming a fluorinated ether compound capable of forming a lubricating layer with better adhesion to the protective layer. Additionally, in Y... 1 and Y 2 When both are hydrogen atoms, the adsorption of Y during the protective layer... 1 and Y 2The resulting spatial steric hindrance becomes minimal, R 1 The -NH2 groups contained therein are adsorbed onto the protective layer. Thus, it becomes a fluorinated ether compound capable of forming a lubricating layer with better adhesion to the protective layer.

[0137] In equation (6-1) Y 1 With Y 2 When the amide bonds are bonded together to form a ring structure, a ring structure consisting only of the nitrogen atom constituting the amide bond and the methylene group (-CH2-) is preferred, or a ring structure consisting of a combination of the nitrogen atom constituting the amide bond and the methylene group (-CH2-) and the ether bond (-O-). Considering the chemical stability of the amide bond (-C(=O)-N-) contained in formula (6-1), Y 1 With Y 2 The ring structure formed by bonding together is preferably a five-membered ring or a six-membered ring.

[0138] The total number of carbon atoms contained in formula (6-1) is 1 to 8. From the viewpoint of steric hindrance when adsorbed on the protective layer, it is preferably 1 to 5, and more preferably 1 to 3.

[0139] In equation (6-2), Y 3 It is an alkyl group having 1 to 7 carbon atoms. Alkyl groups having 1 to 7 carbon atoms can be straight-chain or branched. Considering the steric hindrance when adsorbed onto a protective layer, Y... 3 Preferably, it is selected from any one of methyl, ethyl, n-propyl, and isopropyl, and more preferably methyl.

[0140] In equation (6-2), Y 4 It is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Alkyl groups having 1 to 6 carbon atoms can be straight-chain or branched. From the viewpoint of steric hindrance when adsorbed onto a protective layer, Y... 4 Preferably, it is selected from any one of hydrogen atom, methyl, and ethyl, more preferably hydrogen atom or methyl, and most preferably hydrogen atom. If Y 4 If R is a hydrogen atom, then 1 The -NH- groups contained therein adsorb onto the protective layer, thus becoming a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer.

[0141] Y in equation (6-2) 3 With Y 4 It can also be a ring structure formed by bonds between the elements. 3 With Y 4 The cyclic structure formed by mutual bonding is preferably a cyclic structure consisting only of amide bonds (-C(=O)-N-) and methylene (-CH2-). From the viewpoint of the chemical stability of the amide bonds contained in formula (6-2), Y 3 With Y4 The ring structure formed by bonding together is preferably a five-membered ring or a six-membered ring.

[0142] The total number of carbon atoms contained in formula (6-2) is 2 to 8. From the viewpoint of steric hindrance when adsorbed on the protective layer, it is preferably 2 to 5, and more preferably 2 to 3.

[0143] In equations (5-4) and (5-5), Y 5 It is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Alkyl groups having 1 to 6 carbon atoms can be straight-chain or branched. From the viewpoint of steric hindrance when adsorbed onto a protective layer, Y... 5 Preferably, it is selected from any one of hydrogen atom, methyl, and ethyl, more preferably hydrogen atom or methyl, and most preferably hydrogen atom. If Y 5 If R is a hydrogen atom, then 1 The -NH- groups contained therein adsorb onto the protective layer, thus becoming a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer.

[0144] In equations (5-4) and (5-5), L represents an integer from 1 to 6. If L is an integer less than 6, the proportion of fluorine atoms in the fluorinated ether compound molecule decreases, which can suppress the increase in the overall surface free energy of the molecule. From the perspective of effectively suppressing the increase in the overall surface free energy of the molecule, L is more preferably an integer less than 3. In addition, from the viewpoint of the stability of the fluorinated ether compound, L is preferably an integer of 2 or more. In order to suppress the increase in the overall surface free energy of the molecule and to become a fluorinated ether compound with good stability, L is most preferably 2 or 3.

[0145] In formulas (5-4) and (5-5), Z is any one or more selected from hydrogen atom, alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, and group represented by formula (6-1) or (6-2), preferably any one of the above groups. The alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms can be straight-chain or branched.

[0146] Z is preferably selected from any one of hydrogen atom, alkyl group having 1 to 3 carbon atoms, and alkoxy group having 1 to 3 carbon atoms, and more preferably selected from any one of hydrogen atom, methyl group, and methoxy group. If Z is selected from any one of hydrogen atom, methyl group, and methoxy group, the proportion of fluorine atoms in the fluorinated ether compound molecule is reduced, which can suppress the increase of the overall surface free energy of the molecule.

[0147] The total number of carbon atoms contained in formula (5-4) or (5-5) is 8 to 18. In order to suppress the decrease in the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably 8 to 15, and more preferably 8 to 13.

[0148] Specifically, R 1 The terminal group represented is preferably any one of the following formulas (10-1) to (10-34), in order to make R 1 The -NH- or -NH2- groups contained therein adsorb onto the protective layer to form a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer. More preferably, it is any one of the following formulas (10-1) to (10-4), (10-10) to (10-14), (10-16) to (10-19), (10-21), (10-22), (10-25) to (10-27), (10-29), (10-31) to (10-34). In particular, in order to suppress the decrease in the proportion of fluorine atoms in the fluorinated ether compound molecule, formula (10-1) or formula (10-12) is preferred.

[0149]

[0150]

[0151]

[0152]

[0153] (-[C]-[D]- indicates the linking group)

[0154] In the fluorinated ether compound of this embodiment represented by formula (1), -[C]-[D]- is a divalent linking group. [C] and [D] in formula (1) are interchangeable. [C] is represented by formula (4-1) above, and [D] is represented by formula (4-2) above. f in formula (4-1) and g in formula (4-2) are integers from 0 to 3.

[0155] For the linking group represented by -[C]-[D]-, from the viewpoint of ease of obtaining raw materials and synthesis, the combination of f in formula (4-1) being 1 and g in formula (4-2) being 0, or the combination of f being 0 and g being 1, is preferred.

[0156] Furthermore, for the linking group represented by -[C]-[D]-, from the viewpoint of adhesion to the protective layer, the combination of f being 2 and g being 0, or the combination of f being 1 and g being 1, is preferred. In the case of f being 2 and g being 0, in the fluorinated ether compound, the orientation of the two hydroxyl groups in formula (4-1) is stereoscopically the same relative to the extension direction of the PFPE chain, and it can be observed that the two hydroxyl groups in formula (4-1) tend to readily adsorb onto the protective layer. Additionally, when f and g are 1 and the bonding order of [C] and [D] is from R... 2When the side is -[D]-[C]-, the hydroxyl groups in the linking group represented by -[D]-[C]- are further apart than each other. Therefore, the intramolecular hydrogen bonds of the fluorinated ether compound represented by formula (1) can be reduced, and its adhesion to the protective layer can be improved.

[0157] In equation (4-2), h is an integer from 2 to 5. Since h is greater than 2, the bonding order of [C] and [D] follows from R. 2 When the side is -[D]-[C]-, the intramolecular hydrogen bonds formed between the hydroxyl groups contained in [D] and between the hydroxyl groups contained in [D] and the hydroxyl groups contained in [C] adjacent to [D] can be reduced. Since h is 5 or less, the proportion of fluorine atoms in the fluorinated ether compound molecule is reduced, which can suppress the increase of the overall surface free energy of the molecule. When g is an integer from 1 to 3, h is preferably an integer from 2 to 4, and most preferably 2.

[0158] In the linking group represented by -[C]-[D]-, the sum of f in formula (4-1) and g in formula (4-2) is 1 to 3. Since the sum of f and g is 1 or more, a lubricating layer with excellent adhesion to the protective layer can be formed by utilizing the adsorption force of the hydroxyl group of the linking group represented by -[C]-[D]- on the protective layer. Since the sum of f and g is 3 or less, the proportion of fluorine atoms in the fluorinated ether compound molecule can be sufficiently ensured. The sum of f and g is preferably 1 or 2, which can be determined according to R. 1 The number of hydroxyl groups contained in -[B]-[A]- is appropriately determined.

[0159] (R 3 (representing the terminal group)

[0160] In equation (1), R 3 The terminal group indicates that the number of hydroxyl groups is 0 or 1. R 3 It is represented by the above formula (2). In formula (2), a represents an integer from 2 to 6, and b represents 0 or 1.

[0161] When b is 0 in equation (2), the proportion of fluorine atoms in the fluorinated ether compound molecule decreases, which can effectively suppress the increase of the overall surface free energy of the molecule.

[0162] In equation (2), b is 1, and X 1 In the case of an organic group with 7 to 18 carbon atoms, which is a group consisting of a carbonyl carbon atom or a nitrogen atom containing an amide bond directly bonded to an aromatic hydrocarbon, the ether bond contained in formula (2) imparts flexibility to the fluorinated ether compound represented by formula (1), thus making it easier to adsorb onto the protective layer.

[0163] In equation (2), b is 1, and X1 In the case of hydrogen atoms, in R 3 The terminal group represented by the symbol has a primary hydroxyl group at its very end (-CH2OH). Compared to secondary hydroxyl groups, primary hydroxyl groups have a stronger adsorption force on the protective layer. Therefore, it is contained in R 3 In the lubricating layer of a fluorinated ether compound with a primary hydroxyl group at the very end (-CH2OH) of the terminal group, a portion of the fluorinated ether compound molecule will not float off the surface of the protective layer, resulting in better adhesion of the protective layer.

[0164] Furthermore, when b is 1 in equation (2), since a is an integer from 2 to 6, therefore, R 3 The terminal group becomes chemically stable and less prone to decomposition. 'a' is preferably an integer from 2 to 4, more preferably 2 or 3. If 'a' is 2 or 3, the proportion of fluorine atoms in the fluorinated ether molecule decreases, which can suppress the increase in the overall surface free energy of the molecule.

[0165] X in equation (2) 1 It is an organic group having 7 to 18 carbon atoms, including a carbonyl carbon atom or a nitrogen atom directly bonded to an aromatic hydrocarbon via an amide bond. In X 1 In the case of an organic group having 7 to 18 carbon atoms, which is a group formed by the direct bonding of a carbonyl carbon atom or nitrogen atom containing an amide bond to an aromatic hydrocarbon, as X 1 It can be used as R as mentioned above. 1 The terminal group is used as an example group. X 1 With R 1 They can be the same or different.

[0166] In equation (2) X 1 In the case of an organic group with 7 to 18 carbon atoms, which is a group formed by the direct bonding of a carbonyl carbon atom or nitrogen atom containing an amide bond to an aromatic hydrocarbon, the fluorinated ether compound represented by formula (1) has organic groups at both ends of the molecule that are groups formed by the direct bonding of a carbonyl carbon atom or nitrogen atom containing an amide bond to an aromatic hydrocarbon. Therefore, the fluorinated ether compound represented by formula (1) can form a lubricating layer with better adhesion to the protective layer.

[0167] Additionally, X in equation (2) 1 In the case of an organic group having 7 to 18 carbon atoms, which is a group formed by the direct bonding of a carbonyl carbon atom or a nitrogen atom containing an amide bond to an aromatic hydrocarbon, R in formula (1) 1 -[B]-[A]-and-[C]-[D]-R 3 Preferably, they have the same structure. In other words, in the fluorinated ether compound represented by formula (1), R 2The PFPE chain is preferably symmetrical on both sides. This is because such fluorinated ether compounds can be easily manufactured at low cost. In this case, b in equation (2) is 0, and X... 1 With R 1 same.

[0168] X in equation (2) 1 Preferably, it contains hydrogen atoms. X 1 Fluorinated ether compounds containing hydrogen atoms exhibit good solubility in solvents. Therefore, lubricants containing these compounds are readily coated onto magnetic recording media, and are thus preferred. Additionally, in X... 1 In the case of hydrogen atoms, regardless of whether b is 0 or 1, it is in R 3 The terminal group (-CH2OH) is configured with a primary hydroxyl group at its very end. Therefore, a portion of the fluorinated ether compound molecule will not float off the surface of the protective layer, resulting in better adhesion of the lubricating layer to the protective layer.

[0169] However, in the fluorinated ether compound of this embodiment represented by formula (1), [C] is directly bonded to R. 3 In the case of R 3 It is not a hydrogen atom (in other words, b in equation (2) is 0 and X is not a hydrogen atom). 1 (For hydrogen atoms). [C] is directly bonded to R. 3 In the case where b is 0 and X is 0 in equation (2) 1 This refers to an organic group with 7 to 18 carbon atoms, formed by the direct bonding of a carbonyl carbon atom or nitrogen atom containing an amide bond to an aromatic hydrocarbon, or, in formula (2), b = 1. This is because [C] is directly bonded to R... 3 In the case of R 3 If the atom is hydrogen, it becomes a fluorinated ether compound with a vicinal diol structure (-CH(OH)-CH(OH)-). As mentioned above, the two adjacent hydroxyl groups in the vicinal diol structure cannot be simultaneously adsorbed onto the protective layer due to steric factors. Therefore, from the viewpoint of magnetic head levitation stability and chemical resistance, a lubricating layer containing a fluorinated ether compound with a vicinal diol structure is not preferred.

[0170] In equation (1), -[C]-[D]-R 3 Preferably, it is any one of the following formulas (7-1) to (7-3), and more preferably, it is a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer.

[0171]

[0172] (In equation (7-1), i represents 1 or 2, and j represents an integer from 1 to 5.)

[0173] (In equation (7-2), k represents an integer from 2 to 5, t represents 0 or 1, and p represents an integer from 1 to 5.)

[0174] (In equation (7-3), q represents 0 or 1, r represents an integer from 1 to 5, and s represents an integer from 1 to 4.)

[0175] In equations (7-1) to (7-3), i in equation (7-1) is 1 or 2, t in equation (7-2) is 0 or 1, and q in equation (7-3) is 0 or 1. Therefore, the total number of hydroxyl groups in -[C]-[D]- is 1 or 2, and -[C]-[D]-R 3 It possesses 2 or 3 hydroxyl groups. Therefore, -[C]-[D]-R 3 Fluorinated ether compounds of any of formulas (7-1) to (7-3) can form a lubricating layer with good adhesion to the protective layer by utilizing the adsorption force of the hydroxyl groups of the fluorinated ether compound on the protective layer.

[0176] In formula (7-1), j is an integer from 1 to 5. In order to easily ensure the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably an integer from 1 to 3, and more preferably 1 or 2.

[0177] In formula (7-2), k is an integer from 2 to 5. To easily ensure the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably 2 or 3, more preferably 2. In addition, in formula (7-2), p is an integer from 1 to 5. To easily ensure the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably an integer from 1 to 3, more preferably 1 or 2.

[0178] In formula (7-3), r is an integer from 1 to 5. To easily ensure the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably an integer from 1 to 3, more preferably 1 or 2. In formula (7-3), s is an integer from 1 to 4. To easily ensure the proportion of fluorine atoms in the fluorinated ether compound molecule, it is preferably an integer from 1 to 3, more preferably 1 or 2.

[0179] In the fluorinated ether compound of this embodiment represented by formula (1), the number of hydroxyl groups contained in the molecule is 3 or more. Therefore, the lubricating layer containing the fluorinated ether compound can obtain sufficient adhesion to the protective layer by utilizing the adsorption force of the hydroxyl groups in the fluorinated ether compound on the protective layer. In addition, the good adhesion between the lubricating layer and the protective layer results in a small surface unevenness, making it less prone to adhesion and detachment. From the viewpoint of suppressing the overall surface free energy of the molecule, the number of hydroxyl groups contained in the molecule of the fluorinated ether compound is preferably 3 to 5, more preferably 3 to 4.

[0180] Specifically, the fluorinated ether compound represented by formula (1) is preferably a compound represented by formulas (AA) to (BB) below. It should be noted that the number of repetitions shown in formulas (AA) to (BB) represents the average degree of polymerization and is therefore not necessarily an integer.

[0181] When the compound represented by formula (1) is any of the compounds represented by formulas (AA) to (BB), the raw materials are readily available and the compound becomes a fluorinated ether compound that can form a lubricating layer that is not prone to adhesion or detachment and provides good adhesion and smoothness to the protective layer.

[0182] In the compounds represented by the following formulas (AA) to (AD), R 1 All are represented by the above formula (10-1) having the structure represented by formula (5-1), with the substituents bonded to the benzene ring in the ortho position. In the compounds represented by formulas (AA) to (AD) below, -[B]-[A]- are represented by formula (3-1) with c=1, and -[C]-[D]- are represented by formula (4-1) with f=1. R 3 As expressed by equation (2) above, a is 2, b is 1, and X 1 It is a hydrogen atom.

[0183] In the compounds represented by the following formula (AA), R 2 It is a PFPE chain represented by the above formula (8-2), where u and v are each 1 to 30. In the compounds represented by the following formula (AB), R... 2 It is a PFPE chain represented by the above formula (8-2), where u is 1 to 30 and v is 0. In the compounds represented by the following formula (AC), R... 2 The PFPE chain is represented by formula (8-4) above. In the compounds represented by formula (AD) below, R... 2 Let be the PFPE chain represented by the above equation (8-5).

[0184] In the compounds represented by the following formulas (AE) and (AF), R 1 The above formula (10-1) is represented by the structure shown in formula (5-1). In formula (AE), the bonded to R 1 The substituents on the benzene ring are in a meta position, and in formula (AF), the substituents are bonded to R. 1 The substituents on the benzene ring are in the para position. In the compound represented by the following formula (AG), R 1 The above equation (10-11) is represented by the structure represented by equation (5-3).

[0185] In the compounds represented by formulas (AE) to (AG) below, -[B]-[A]- is represented by formula (3-1) with c = 1, and -[C]-[D]- is represented by formula (4-1) with f = 1. 3As expressed by equation (2) above, a is 2, b is 1, and X 1 It is a hydrogen atom. R 2 It is a PFPE chain represented by the above formula (8-2), where u and v are each 1 to 30.

[0186] In the compounds represented by the formulas (AH) to (AM) below, R 1 All have the structure represented by equation (5-1) and are bonded to R. 1 The substituents on the benzene ring are in the para position. The compound represented by the following formula (AH) has R in the para position. 1 As indicated by the above formula (10-27), R in the compound represented by the following formula (AI) 1 As indicated by the above formula (10-28), R in the compound represented by the following formula (AJ) 1 As represented by the above formula (10-8), R in the compound represented by the following formula (AK) 1 As represented by the above formula (10-12), R in the compound represented by the following formula (AL) 1 As indicated by the above formula (10-29), R in the compound represented by the following formula (AM) 1 It is represented by the above formula (10-30).

[0187] In the compounds represented by the following formulas (AN) to (AR), R 1 All have the structure represented by formula (5-4). R in the compounds represented by the following formula (AN) 1 As indicated by the above formula (10-18), R in the compound represented by the following formula (AO) 1 As represented by the above formula (10-31), R in the compound represented by the following formula (AP) 1 As represented by the above formula (10-32), R in the compound represented by the following formula (AQ) 1 As indicated by the above formula (10-33), R in the compound represented by the following formula (AR) 1 It is represented by the above formula (10-34).

[0188] In the compounds represented by the following formulas (AS) and (AT), R 1 It has the structure represented by formula (5-5). R in the compound represented by the following formula (AS) 1 As indicated by the above formula (10-21), R in the compound represented by the following formula (AT) 1 It is represented by the above formula (10-23).

[0189] In the compounds represented by formulas (AH) to (AT) below, -[B]-[A]- are all represented by formula (3-1) with c = 1, and -[C]-[D]- are represented by formula (4-1) with f = 1.3 As expressed by equation (2) above, a is 2, b is 1, and X 1 It is a hydrogen atom. R 2 It is a PFPE chain represented by the above formula (8-2), where u and v are each 1 to 30.

[0190] In the compounds represented by the following formulas (AU) to (AZ), R 1 All are represented by the above formula (10-1) having the structure represented by formula (5-1), and the substituents bonded to the benzene ring are in the ortho position, R 2 It is a PFPE chain represented by the above formula (8-2), where u and v are each 1 to 30.

[0191] In the compounds represented by the following formula (AU), -[B]-[A]- is represented by formula (3-1) with c = 1, and -[C]-[D]- is represented by formula (4-1) with f = 1. R 3 As expressed by equation (2) above, a is 6, b is 1, and X 1 It is a hydrogen atom.

[0192] In the compounds represented by the following formula (AV), -[B]-[A]- is represented by formula (3-1) with c = 1, and -[C]-[D]- is represented by formula (4-1) with f = 2. R 3 As expressed by equation (2) above, a is 2, b is 1, and X 1 It is a hydrogen atom.

[0193] In the compounds represented by the following formula (AW), -[B]-[A]- is represented by formula (3-1) with c = 2, and -[C]-[D]- is represented by formula (4-1) with f = 1. R 3 As expressed by equation (2) above, a is 2, b is 1, and X 1 It is a hydrogen atom.

[0194] In the compounds represented by the following formula (AX), -[B]-[A]- is represented by formula (3-1) with c = 2, -[C]-[D]- is represented by formula (4-2) with g = 1 and h = 2. R 3 As expressed by equation (2) above, b is 0, X 1 It is a hydrogen atom.

[0195] In the compounds represented by the following formula (AY), -[B]-[A]- is represented by formula (3-1), and c is 1. -[C]-[D]- is represented by formulas (4-1) and (4-2), and f is 1, g is 1, and h is 5. The bonding order of [C] and [D] starts from R. 2 The side view is -[C]-[D]-. R 3 As expressed by equation (2) above, b is 0, X 1 It is a hydrogen atom.

[0196] In the compounds represented by the following formula (AZ), -[B]-[A]- is represented by formula (3-1), and c is 1. -[C]-[D]- is represented by formulas (4-1) and (4-2), and f is 1, g is 1, and h is 2. The bonding order of [C] and [D] starts from R. 2 The side view is -[D]-[C]-. R 3 As expressed by equation (2) above, a is 2, b is 1, and X 1 It is a hydrogen atom.

[0197] In the compounds represented by formulas (BA) and (BB) below, R 1 All are represented by the above formula (10-12) having the structure represented by formula (5-1), and the substituents bonded to the benzene ring are in the para position. R 2 Let f be the PFPE chain represented by equation (8-4) above. -[C]-[D]- is represented by equation (4-1), where f is 2. R 3 As expressed by equation (2) above, b is 0, X 1 With R 1 same.

[0198] In the compounds represented by formula (BA) below, -[B]-[A]- is represented by formula (3-1), and c is 1. In the compounds represented by formula (BB) below, -[B]-[A]- is represented by formula (3-1), and c is 2.

[0199]

[0200] (In formula (AA), maa and naa represent the average degree of polymerization, each ranging from 1 to 30.)

[0201] (In formula (AB), nab represents the average degree of polymerization, and it ranges from 1 to 30.)

[0202] (In formula (AC), nac represents the average degree of polymerization, and ranges from 1 to 30.)

[0203] (In formula (AD), nad represents the average degree of polymerization, and ranges from 1 to 30.)

[0204]

[0205] (In formula (AE), mae and nae represent the average degree of polymerization, each ranging from 1 to 30.)

[0206] (In formula (AF), maf and naf represent the average degree of polymerization, each ranging from 1 to 30.)

[0207] (In formula (AG), mag and nag represent the average degree of polymerization, each ranging from 1 to 30.)

[0208] (In formula (AH), mah and nah represent the average degree of polymerization, each ranging from 1 to 30.)

[0209]

[0210] (In formula (AI), mai and nai represent the average degree of polymerization, each ranging from 1 to 30.)

[0211] (In formula (AJ), maj and naj represent the average degree of polymerization, each ranging from 1 to 30.)

[0212] (In formula (AK), mak and nak represent the average degree of polymerization, each ranging from 1 to 30.)

[0213] (In formula (AL), mal and nal represent the average degree of polymerization, each ranging from 1 to 30.)

[0214]

[0215] (In formula (AM), mam and nam represent the average degree of polymerization, each ranging from 1 to 30.)

[0216] (In formula (AN), man and nan represent the average degree of polymerization, each ranging from 1 to 30.)

[0217] (In formula (AO), maο and naο represent the average degree of polymerization, each ranging from 1 to 30.)

[0218] (In formula (AP), map and nap represent the average degree of aggregation, each ranging from 1 to 30.)

[0219]

[0220] (In formula (AQ), maq and naq represent the average degree of polymerization, each ranging from 1 to 30.)

[0221] (In formula (AR), mar and nar represent the average degree of polymerization, each ranging from 1 to 30.)

[0222] (In formula (AS), mas and nas represent the average degree of polymerization, each ranging from 1 to 30.)

[0223] (In formula (AT), mat and nat represent the average degree of polymerization, each ranging from 1 to 30.)

[0224]

[0225] (In formula (AU), mau and nau represent the average degree of polymerization, each ranging from 1 to 30.)

[0226] (In formula (AV), mav and nav represent the average degree of polymerization, each ranging from 1 to 30.)

[0227] (In formula (AW), maw and naw represent the average degree of polymerization, each ranging from 1 to 30.)

[0228] (In formula (AX), max and nax represent the average degree of polymerization, each ranging from 1 to 30.)

[0229]

[0230] (In formula (AY), may and nay represent the average degree of polymerization, each ranging from 1 to 30.)

[0231] (In formula (AZ), maz and naz represent the average degree of polymerization, each ranging from 1 to 30.)

[0232] (In formula (BA), nba represents the average degree of polymerization, and ranges from 1 to 30.)

[0233] (In formula (BB), nbb represents the average degree of polymerization, and ranges from 1 to 30.)

[0234] The number-average molecular weight (Mn) of the fluorinated ether compound in this embodiment is preferably in the range of 500 to 10,000, more preferably in the range of 700 to 7,000, and particularly preferably in the range of 800 to 4,000.

[0235] If the number-average molecular weight is 500 or higher, the lubricant containing the fluorinated ether compound of this embodiment becomes less prone to evaporation. Therefore, if the number-average molecular weight is 500 or higher, it becomes a fluorinated ether compound capable of forming a lubricating layer that is less prone to adhesion and detachment. Furthermore, if the number-average molecular weight is 10,000 or lower, the viscosity of the fluorinated ether compound does not become excessively high, resulting in a viscosity suitable for use as a lubricant. For easy handling when applied as a lubricant, the number-average molecular weight of the fluorinated ether compound is more preferably 4,000 or lower.

[0236] Considering the ease of obtaining raw materials for PFPE chains, the number-average molecular weight of the fluorinated ether compound in this embodiment is more preferably in the range of 1000 to 3000. Furthermore, even with a thinner film thickness, the lubricating layer containing a fluorinated ether compound in the range of 1000 to 3000 does not suffer from poor coverage, resulting in a lubricating layer with good chemical resistance and wear resistance. From the viewpoint of suppressing adhesion and detachment in the lubricating layer containing it, and the thinning of the lubricating layer, the fluorinated ether compound in the range of 1000 to 3000 offers the best balance of performance.

[0237] In the fluorinated ether compound of this embodiment, R 2The ratio of the number-average molecular weight of the PFPE chain to the number-average molecular weight of the entire molecule (PFPE chain / molecular total) is preferably 0.45 to 0.90, more preferably 0.55 to 0.85. If the above-mentioned number-average molecular weight ratio is 0.45 or higher, the proportion of fluorine atoms in the fluorinated ether compound molecule decreases, which can suppress the increase in the surface free energy of the entire molecule. Furthermore, if the above-mentioned number-average molecular weight ratio is 0.90 or lower, then relative to the length of the PFPE chain, the R-type molecular weight distributions at both ends of the PFPE chain are... 1 -[B]-[A]-and-[C]-[D]-R 3 The amount of hydroxyl groups contained therein becomes appropriate. Therefore, it becomes a fluorinated ether compound that can form a lubricating layer with better adhesion to the protective layer.

[0238] "Manufacturing method"

[0239] The method for manufacturing the fluorinated ether compound in this embodiment is not particularly limited, and conventionally known manufacturing methods can be used. For example, the fluorinated ether compound in this embodiment can be manufactured using the methods shown below.

[0240] First, prepare R corresponding to equation (1). 2 A fluorinated compound with a PFPE chain and hydroxymethyl (-CH2OH) groups at both ends of the molecule.

[0241] Next, the hydroxyl group of the hydroxymethyl group at one end of the above-mentioned fluorinated compound is replaced with the R in formula (1). 1 The group consisting of -[B]-[A]- (reaction 1). Then, the hydroxyl group of the hydroxymethyl group at the other end is replaced with the group consisting of -[C]-[D]-R in formula (1). 3 The group that forms it (reaction 2).

[0242] The first and second reactions can be carried out using methods known in the past, and can be appropriately determined according to the type of terminal group in formula (1). Alternatively, either the first or the second reaction can be carried out first.

[0243] The fluorinated ether compound represented by formula (1) can be obtained by the above method.

[0244] Lubricant for magnetic recording media

[0245] The lubricant for the magnetic recording medium in this embodiment includes a fluorinated ether compound represented by formula (1).

[0246] For the lubricant of this embodiment, it can be used by mixing with known materials that are used as the lubricant, as long as it does not impair the properties due to the inclusion of the fluorinated ether compound represented by formula (1).

[0247] Specific examples of known materials include, for instance, FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), and Moresco A20H (manufactured by Moresco). The known materials used in combination with the lubricant of this embodiment are preferably materials with a number average molecular weight of 1000 to 10000.

[0248] In the case where the lubricant of this embodiment contains materials other than the fluorinated ether compound represented by formula (1), the content of the fluorinated ether compound represented by formula (1) in the lubricant is preferably 50% by mass or more, more preferably 70% by mass or more. The content of the fluorinated ether compound represented by formula (1) in the lubricant may be 80% by mass or more, or 90% by mass or more.

[0249] The lubricant of this embodiment contains a fluorinated ether compound represented by formula (1), thus forming a lubricating layer with good adhesion and smoothness to the protective layer and capable of inhibiting adhesion and detachment.

[0250] [Magnetic recording media]

[0251] The magnetic recording medium of this embodiment is a magnetic recording medium on a substrate having at least a magnetic layer, a protective layer and a lubricating layer disposed therein in sequence.

[0252] In the magnetic recording medium of this embodiment, one or more base layers can be provided between the substrate and the magnetic layer as needed. Alternatively, an adhesion layer and / or a soft magnetic layer can be provided between the base layer and the substrate.

[0253] Figure 1 A schematic cross-sectional view illustrating one embodiment of the magnetic recording medium of the present invention.

[0254] The magnetic recording medium 10 of this embodiment has a structure in which 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 are sequentially disposed on a substrate 11.

[0255] "Substrate"

[0256] As substrate 11, for example, a non-magnetic substrate obtained by forming a film made of NiP or NiP alloy on a substrate made of a metal or alloy material such as Al or Al alloy can be used.

[0257] In addition, as substrate 11, a non-magnetic substrate made of non-metallic materials such as glass, ceramic, silicon, silicon carbide, carbon, and resin can be used, or a non-magnetic substrate obtained by forming a NiP or NiP alloy film on a substrate made of these non-metallic materials can be used.

[0258] Glass substrates are rigid and have excellent smoothness, making them suitable for high recording density. Examples of glass substrates include aluminosilicate glass substrates. Chemically reinforced aluminosilicate glass substrates are particularly suitable.

[0259] The surface roughness of the main surface of the substrate 11 is preferably ultra-smooth, that is, Rmax is less than 6 nm and Ra is less than 0.6 nm. The surface roughness Rmax and Ra referred to here are roughnesses specified in JIS B0601.

[0260] "Adhesion layer"

[0261] The adhesion layer 12 prevents corrosion of the substrate 11 that occurs when the substrate 11 and the soft magnetic layer 13 to be disposed on the adhesion layer 12 are arranged in contact.

[0262] The material of the adhesion layer 12 can be suitably 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.

[0263] "Soft magnetic layer"

[0264] The soft magnetic layer 13 preferably has 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 in which the soft magnetic films above and below the intermediate layer are antiferromagnetically coupled (AFC) by sandwiching an intermediate layer made of Ru film between the two soft magnetic films.

[0265] Materials used for the first and second soft magnetic films include CoZrTa alloys and CoFe alloys.

[0266] Preferably, any one of Zr, Ta, or 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. As a result, the orientation of the first substrate layer (seed layer) can be improved, and the rise of the magnetic head can be reduced.

[0267] The soft magnetic layer 13 can be formed, for example, by sputtering.

[0268] "First basal layer"

[0269] The first substrate layer 14 is a layer used to control the orientation and crystal size of the second substrate layer 15 and the magnetic layer 16 disposed thereon.

[0270] Examples of first base layers 14 include base layers composed of Cr layers, Ta layers, Ru layers, or CrMo alloy layers, CoW alloy layers, CrW alloy layers, CrV alloy layers, CrTi alloy layers, etc.

[0271] The first base layer 14 can be formed, for example, by sputtering.

[0272] "Second basal layer"

[0273] The second substrate layer 15 is a layer whose orientation is controlled to improve the magnetic layer 16. The second substrate layer 15 is preferably a layer made of Ru or a Ru alloy.

[0274] 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.

[0275] The second base layer 15 can be formed, for example, by sputtering.

[0276] "Magnetic layer"

[0277] 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 is a layer containing Co and Pt. The magnetic layer 16 may also be a layer containing oxides, Cr, B, Cu, Ta, Zr, etc., to improve the SNR (Signal to Noise Ratio) characteristics.

[0278] Examples of oxides contained in the magnetic layer 16 include SiO2, SiO, Cr2O3, CoO, Ta2O3, and TiO2.

[0279] The magnetic layer 16 can consist of a single layer or multiple magnetic layers comprising different materials.

[0280] For example, when the magnetic layer 16 is composed of three layers—a first magnetic layer, a second magnetic layer, and a third magnetic layer—layered sequentially from bottom to top, the first magnetic layer is preferably a granular structure formed of a material containing Co, Cr, Pt, and also oxides. As the oxide contained in the first magnetic layer, oxides of, for example, Cr, Si, Ta, Al, Ti, Mg, Co, etc., are preferred. Among these, TiO2, Cr2O3, SiO2, etc., are particularly suitable. Furthermore, the first magnetic layer is preferably made of a composite oxide containing two or more oxides. Among these, Cr2O3-SiO2, Cr2O3-TiO2, SiO2-TiO2, etc., are particularly suitable.

[0281] The first magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re, in addition to Co, Cr, Pt, and oxides.

[0282] The second magnetic layer can be made of the same material as the first magnetic layer. The second magnetic layer is preferably granular.

[0283] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, and Pt but without oxides. In addition to Co, Cr, and Pt, the third magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn.

[0284] 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 composed 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.

[0285] The non-magnetic layer disposed between adjacent magnetic layers of magnetic layer 16 may 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.).

[0286] In the non-magnetic layer disposed between adjacent magnetic layers of magnetic layer 16, an alloy material comprising oxides, metal nitrides, or metal carbides is preferably used. 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.

[0287] Non-magnetic layers can be formed, for example, using sputtering.

[0288] 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 may also be a magnetic layer for in-plane magnetic recording.

[0289] The magnetic layer 16 can be formed using any previously known method, such as vapor deposition, ion beam sputtering, or magnetron sputtering. The magnetic layer 16 is typically formed using sputtering.

[0290] "Protective layer"

[0291] 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.

[0292] 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 between it and 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.

[0293] The adhesion between the carbon-based protective layer and the lubricating layer 18 can be controlled by making the carbon-based protective layer hydrogenated carbon and / or carbon nitride and adjusting the hydrogen and / or nitrogen content in the carbon-based protective layer. The hydrogen content in the carbon-based protective layer is preferably 3 atomic% to 20 atomic% when measured using hydrogen forward scattering (HFS). Furthermore, the nitrogen content in the carbon-based protective layer is preferably 4 atomic% to 15 atomic% when measured using X-ray photoelectron spectroscopy (XPS).

[0294] 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. The carbon-based protective layer is suitable, for example, as a tilted layer, i.e., containing nitrogen on the lubrication layer 18 side of the protective layer 17 and hydrogen on the magnetic layer 16 side of the protective layer 17. In this case, the adhesion between the magnetic layer 16 and the lubrication layer 18 and the carbon-based protective layer is further improved. This is because the nitrogen in the protective layer 17 acts as an active site, promoting bonding with the lubrication layer 18. The hydrogen or nitrogen in the carbon-based protective layer also functions as active sites.

[0295] 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.

[0296] The film formation method for the protective layer 17 can be sputtering using a carbon-containing target, CVD (chemical vapor deposition) using hydrocarbon raw materials such as ethylene or toluene, or IBD (ion beam deposition).

[0297] When forming a carbon-based protective layer as protective layer 17, film deposition can be performed, for example, using 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 using plasma CVD. The amorphous carbon protective layer obtained by plasma CVD has a uniform surface and low roughness.

[0298] "Lubrication layer"

[0299] 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.

[0300] like Figure 1 As shown, the lubricating layer 18 is formed on the protective layer 17 in a contact manner. The lubricating layer 18 contains the aforementioned fluorinated ether compound.

[0301] When the protective layer 17 disposed beneath the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 bonds with the protective layer 17 with a particularly high bonding strength. As a result, it is easy to obtain a magnetic recording medium 10 that covers the surface of the protective layer 17 with a high coverage even when the thickness of the lubricating layer 18 is relatively thin, and it is possible to effectively prevent contamination of the surface of the magnetic recording medium 10.

[0302] The average film thickness of the lubricating layer 18 is preferably... More preferably If the average film thickness of the lubricating layer 18 is 0.5 nm or more, the lubricating layer 18 will not become island-like or mesh-like, but will be formed with a uniform film thickness. Therefore, the surface of the protective layer 17 can be covered with the lubricating layer 18 with a high coverage rate. In addition, 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 significantly reduced.

[0303] Without utilizing the lubricating layer 18 to cover the surface of the protective layer 17 with a sufficiently high coverage, environmental substances adsorbed onto the surface of the magnetic recording medium 10 penetrate through the gaps in the lubricating layer 18 and infiltrate below the lubricating layer 18. These infiltrated environmental substances in the lower layer of the lubricating layer 18 adsorb and bind to the protective layer 17, generating contaminants. Then, 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.

[0304] Examples of environmental pollutants include 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 contained in ionic impurities include sodium ions and potassium ions. Examples of inorganic ions contained in ionic impurities include chloride ions, bromide ions, nitrate ions, sulfate ions, and ammonium ions. Examples of organic ions contained in ionic impurities include oxalate ions and formate ions.

[0305] "Methods for forming a lubricating layer"

[0306] As a method for forming the lubricating layer 18, one can exemplify the following method: prepare a magnetic recording medium in the manufacturing process on which each layer up to the protective layer 17 is formed on the substrate 11, apply a lubricating layer forming solution to the protective layer 17, and allow it to dry.

[0307] The solution for forming the lubricating layer can be obtained, for example, by dissolving the lubricant of the magnetic recording medium described above in a solvent as needed and adjusting the viscosity and concentration to be suitable for the coating method.

[0308] Examples of solvents used in solutions for forming a lubricating layer include fluorinated solvents such as Bartel XF (trade name, manufactured by Mitsui Dupont Froroike Mikaru Co., Ltd.).

[0309] There are no particular limitations on the application method of the solution for forming the lubricating layer; examples include spin coating, spray coating, paper coating, and impregnation.

[0310] When using the immersion method, the following method can be employed, for example. First, the substrate 11, to which the protective layer 17 has been formed, is immersed in a lubricant layer forming solution placed in the immersion tank of the immersion coating apparatus. Next, the substrate 11 is lifted from the immersion tank at a predetermined speed. As a result, the lubricant layer forming solution is applied to the surface of the protective layer 17 on the substrate 11.

[0311] 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.

[0312] 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.

[0313] The heat treatment temperature is preferably set to 100°C to 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 fully achieved. Furthermore, by setting the heat treatment temperature below 180°C, thermal decomposition of the lubricating layer 18 due to heat treatment can be prevented. The heat treatment time is preferably set to 10 minutes to 120 minutes.

[0314] In this embodiment, in order to further improve the adhesion of the lubricating layer 18 to the protective layer 17, the lubricating layer 18 of the substrate 11 before or after heat treatment can be treated with ultraviolet (UV) irradiation.

[0315] The magnetic recording medium 10 of this embodiment is a magnetic recording medium on a substrate 11 in which at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are sequentially disposed. 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. The lubricating layer 18 has good adhesion and smoothness to the protective layer 17, which can suppress adhesion and detachment. Therefore, the magnetic head of the magnetic recording medium 10 of this embodiment has excellent levitation stability.

[0316] Furthermore, since the magnetic recording medium 10 of this embodiment has a lubricating layer 18 that is less prone to adhesion, the magnetic pitch can be further reduced. In addition, since the magnetic recording medium 10 of this embodiment has a lubricating layer 18 that is less prone to peeling, the rotational speed of the magnetic recording medium can be increased. Therefore, the magnetic recording medium 10 of this embodiment can contribute to increasing the recording density and capacity of the magnetic recording medium. Therefore, the magnetic recording medium 10 of this embodiment is suitable as a disk drive for use in disk drives, especially those employing LUL (Load Unload) mode.

[0317] In contrast, conventional magnetic recording media suffer from the following problems: the lubricating layer does not adhere sufficiently to the protective layer. Therefore, reducing the magnetic pitch can easily lead to adhesion, and increasing the rotational speed of the magnetic recording medium can easily cause it to detach. Consequently, in conventional magnetic recording media, it is difficult to reduce the magnetic pitch or increase the rotational speed of the magnetic recording medium while maintaining reliability and durability.

[0318] Example

[0319] The present invention will now be described in more detail using examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

[0320] [Nuclear Magnetic Resonance (NMR) Measurement Methods]

[0321] The structures of the compounds obtained in the following examples and comparative examples were determined using an NMR apparatus (AVANCEIII-400) manufactured by Blu-ray Bio-Spin Co., Ltd. 1 H-NMR determination and 19 The results obtained from F-NMR measurements were validated.

[0322] In the NMR determination, approximately 10 mg of the sample is weighed and dissolved in approximately 0.5 mL of deuterated acetone (with hexafluorobenzene added as a reference substance). 1 The baseline for the H-NMR chemical shift is set at 2.05 ppm for the acetone peak. 19 The baseline for F-NMR chemical shift is set at -164.7 ppm for the peak of hexafluorobenzene.

[0323] The number-average molecular weight (Mn) of each compound is derived from 19 The results were calculated using F-NMR measurements. Specifically, this was achieved by utilizing... 19 The number of repeating units in the PFPE chain is calculated from the integrated intensity of fluorine atoms measured by F-NMR. The number-average molecular weight of the PFPE chain and the number-average molecular weight of the whole molecule are determined for each compound, and their ratio is calculated (PFPE ratio = PFPE chain Mn / whole molecule Mn).

[0324] [Example 1]

[0325] The compound (AA) represented by the above formula (AA) was obtained by the method shown below (in formula (AA), maa, which represents the average degree of polymerization, is 6.2, and naa, which represents the average degree of polymerization, is 6.2).

[0326] First, 2-hydroxybenzamide was reacted with epibromoethanol to synthesize the compound represented by formula (11-1). Then, ethylene glycol monoallyl ether was reacted with 3,4-dihydro-2H-pyran, and after protecting the hydroxyl group with a tetrahydropyran group, the double bond was oxidized using m-chloroperoxybenzoic acid, thereby synthesizing the compound represented by formula (12-1).

[0327]

[0328] Under a nitrogen atmosphere, HOCH2CF2O(CF2CF2O) was added to a 200mL round-bottom flask. u(CF2O) v A fluoropolyether (number average molecular weight 1300, molecular weight distribution 1.1) (40.0 g) representing CF2CH2OH (where u represents the average degree of polymerization and v represents the average degree of polymerization 6.2) (40.0 g), a compound represented by formula (11-1) (3.57 g), and t-BuOH (tert-butanol) (40.0 mL) were stirred at room temperature until homogeneous. Further, t-BuOK (potassium tert-butoxide) (1.04 g) was added to the above-mentioned flask, heated to 70°C, and stirred for 12 hours to allow the reaction to proceed.

[0329] The obtained reaction product was then cooled to 25°C, water was added, and ethyl acetate was added as a solvent to extract the organic layer, followed by washing with water. Anhydrous sodium sulfate was added to the organic layer for dehydration, and the desiccant was filtered off. The filtrate was then concentrated. The residue was purified by silica gel column chromatography to obtain the compound represented by the following formula (13-1) (18.4 g).

[0330]

[0331] (In equation (13-1), maa, representing the average degree of polymerization, is 6.2, and naa, representing the average degree of polymerization, is 6.2.)

[0332] Under a nitrogen atmosphere, 18.4 g of the compound represented by formula (13-1), 2.74 g of the compound represented by formula (12-1), and 65.0 mL of t-BuOH (tert-butanol) were added to a 200 mL flask and stirred at room temperature until homogeneous. Further, 0.41 g of t-BuOK (potassium tert-butoxide) was added to the above flask, and the mixture was heated to 70 °C and stirred for 16 hours to allow the reaction to proceed.

[0333] The resulting reaction product was then cooled to 25°C, and 7% hydrogen chloride / methanol reagent (64.1 g) was added. The mixture was stirred at room temperature for 3 hours to carry out the deprotection reaction.

[0334] The obtained reaction product was neutralized by adding 250 mL of 7% sodium bicarbonate aqueous solution, followed by extraction of the organic layer with ethyl acetate and washing with water. Anhydrous sodium sulfate was added to the organic layer for dehydration, and the mixture was filtered through a drying agent. The filtrate was then concentrated. The residue was purified by silica gel column chromatography to give 13.9 g of compound (AA).

[0335] The resulting compound (AA) was subjected to [further processing]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0336] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0337] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0338] [Example 2]

[0339] The compound (AB) represented by the above formula (AB) was obtained by the method shown below (in formula (AB), the average degree of polymerization, nab, is 9.7).

[0340] Using HOCH2CF2O(CF2CF2O) z A fluorinated polyether (number average molecular weight of 1300, molecular weight distribution of 1.1) (40.0 g) representing CF2CH2OH (where z represents the average degree of polymerization of 9.7) was used instead of HOCH2CF2O (CF2CF2O) in Example 1. u (CF2O) v The fluorinated polyether (number average molecular weight 1300, molecular weight distribution 1.1) represented by CF2CH2OH (where u represents the average degree of polymerization and v represents the average degree of polymerization 6.2) was subjected to the same operation as in Example 1 to obtain 14.2 g of compound (AB).

[0341] The resulting compound (AB) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0342] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0343] 19 F-NMR (acetone-d6): δ [ppm] = -78.57 (4F), -88.92 to -89.57 (38.8F)

[0344] [Example 3]

[0345] The compound (AC) represented by the above formula (AC) was obtained by the method shown below (in formula (AC), nac, which represents the average degree of polymerization, is 6.2).

[0346] Use HOCH2CF2CF2O(CF2CF2CF2O) x A fluorinated polyether (number average molecular weight of 1300, molecular weight distribution of 1.1) (40.0 g) representing CF2CF2CH2OH (where x represents the average degree of polymerization of 6.2) was used instead of HOCH2CF2O (CF2CF2O) in Example 1. u (CF2O) v The fluorinated polyether (number average molecular weight 1300, molecular weight distribution 1.1) represented by CF2CH2OH (where u represents the average degree of polymerization and v represents the average degree of polymerization 6.2) was subjected to the same operation as in Example 1 to obtain 13.6 g of compound (AC).

[0347] The resulting compound (AC) was subjected to [further processing]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0348] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0349] 19 F-NMR (acetone-d6): δ [ppm] = -84.22 (24.8F), -86.40 (4F), -124.30 (4F), -130.08 (12.4F)

[0350] [Example 4]

[0351] The compound (AD) represented by the above formula (AD) was obtained by the method shown below (in formula (AD), nad, which represents the average degree of polymerization, is 4.3).

[0352] Use HOCH2CF2CF2CF2O(CF2CF2CF2CF2O) y The fluorinated polyether represented by CF2CF2CF2CH2OH (where y represents the average degree of polymerization, which is 4.3) (40.0 g) with a number-average molecular weight of 1300 and a molecular weight distribution of 1.1 was used instead of HOCH2CF2O (CF2CF2O) in Example 1. u (CF2O) vThe fluorinated polyether (number average molecular weight 1300, molecular weight distribution 1.1) represented by CF2CH2OH (where u represents the average degree of polymerization and v represents the average degree of polymerization 6.2) was subjected to the same operation as in Example 1 to obtain 14.2 g of compound (AD).

[0353] The resulting compound (AD) was processed. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0354] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0355] 19 F-NMR (acetone-d6): δ [ppm] = -83.70 (21.2F), -123.32 (4F), -125.85 (17.2F), -127.63 (4F)

[0356] [Example 5]

[0357] The compound (AE) represented by the above formula (AE) was obtained by the method shown below (in formula (AE), mae, which represents the average degree of polymerization, is 6.2, and nae, which represents the average degree of polymerization, is 6.2).

[0358] First, 3-hydroxybenzamide was reacted with epibromool to synthesize the compound represented by the following formula (11-2).

[0359]

[0360] The compound (11-2) (3.57 g) represented by formula (11-2) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 13.2 g of compound (AE).

[0361] The resulting compound (AE) was subjected to 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0362] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0363] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0364] [Example 6]

[0365] The compound (AF) represented by the above formula (AF) was obtained by the method shown below (in formula (AF), maf, which represents the average degree of polymerization, is 6.2, and naf, which represents the average degree of polymerization, is 6.2).

[0366] First, 4-hydroxybenzamide was reacted with epibromool to synthesize the compound represented by the following formula (11-3).

[0367]

[0368] The compound (11-3) (3.57 g) represented by formula (11-3) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.5 g of compound (AF).

[0369] The resulting compound (AF) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0370] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0371] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0372] [Example 7]

[0373] The compound (AG) represented by the above formula (AG) was obtained by the method shown below (in formula (AG), mag, which represents the average degree of polymerization, is 6.2, and nag, which represents the average degree of polymerization, is 6.2).

[0374] First, 6-hydroxy-2-naphthylcarboxamide was reacted with epibromool to synthesize the compound represented by the following formula (11-4).

[0375]

[0376] The compound (11-4) (4.49 g) represented by formula (11-4) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.3 g of compound (AG).

[0377] The resulting compound (AG) was subjected to 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0378] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹¹H), 4.10-4.80 (¹⁰H), 6.50-6.70 (¹H), 7.00-8.10 (⁷H)

[0379] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0380] [Example 8]

[0381] The compound (AH) represented by the above formula (AH) was obtained by the method shown below (in formula (AH), mAh, which represents the average degree of polymerization, is 6.2, and nah, which represents the average degree of polymerization, is 6.2).

[0382] First, methyl 4-hydroxybenzoate was reacted with heptaylamine, and the resulting compound was reacted with epibromool to synthesize the compound represented by the following formula (11-5).

[0383]

[0384] The compound (11-5) (5.38 g) represented by formula (11-5) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.7 g of compound (AH).

[0385] The resulting compound (AH) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0386] 1¹H NMR (acetone-d6): δ [ppm] = 0.95 (3H), 1.20–1.60 (10H), 3.40–4.00 (13H), 4.10–4.80 (10H), 6.50–6.70 (1H), 7.00–8.10 (4H)

[0387] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0388] [Example 9]

[0389] The compound (AI) represented by the above formula (AI) was obtained by the method shown below (in formula (AI), mai, which represents the average degree of polymerization, is 6.2, and nai, which represents the average degree of polymerization, is 6.2).

[0390] First, methyl 4-hydroxybenzoate was reacted with dipropylamine, and the resulting compound was reacted with epibromool to synthesize the compound represented by the following formula (11-6).

[0391]

[0392] Using compound (11-6) (5.12 g) of formula (11-6) instead of compound (11-1) of formula (11-1) used in Example 1, otherwise the same operation as in Example 1 was performed to obtain 14.6 g of compound (AI).

[0393] The resulting compound (AI) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0394] 1 ¹H-NMR (acetone-d6): δ [ppm] = 0.98 (6H), 1.41 (4H), 3.40–4.00 (15H), 4.10–4.80 (10H), 7.00–8.10 (4H)

[0395] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0396] [Example 10]

[0397] The compound (AJ) represented by the above formula (AJ) was obtained by the method shown below (in formula (AJ), maj, which represents the average degree of polymerization, is 6.2, and naj, which represents the average degree of polymerization, is 6.2).

[0398] First, 4-(1-piperidinylcarbonyl)phenol was reacted with epibromool to synthesize the compound represented by the following formula (11-7).

[0399]

[0400] The compound (11-7) (4.82 g) represented by formula (11-7) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.5 g of compound (AJ).

[0401] The resulting compound (AJ) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0402] 1 ¹H-NMR (acetone-d6): δ [ppm] = 1.42 (6H), 2.82-3.25 (4H), 3.40-4.00 (11H), 4.10-4.80 (10H), 7.00-8.10 (4H)

[0403] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0404] [Example 11]

[0405] The compound (AK) represented by the above formula (AK) was obtained by the method shown below (in formula (AK), mak, which represents the average degree of polymerization, is 6.2, and nak, which represents the average degree of polymerization, is 6.2).

[0406] First, 4'-hydroxyacetylaniline was reacted with epibromoethanol to synthesize the compound represented by the following formula (11-8).

[0407]

[0408] The compound (11-8) (3.83 g) represented by formula (11-8) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.0 g of compound (AK).

[0409] The obtained compound (AK) was subjected to 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0410] 1 ¹H-NMR (acetone-d6): δ [ppm] = 2.09 (3H), 3.40–4.00 (11H), 4.10–4.80 (10H), 6.50–7.50 (4H), 9.00 (1H)

[0411] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0412] [Example 12]

[0413] The compound (AL) represented by the above formula (AL) was obtained by the method shown below (in formula (AL), mal, which represents the average degree of polymerization, is 6.2, and nal, which represents the average degree of polymerization, is 6.2).

[0414] First, 4-aminophenol was reacted with octanoic acid, and the resulting compound was reacted with epibromool to synthesize the compound represented by the following formula (11-9).

[0415]

[0416] The compound (11-9) (5.38 g) represented by formula (11-9) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.7 g of compound (AL).

[0417] The resulting compound (AL) was subjected to [further processing]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0418] 1 ¹H NMR (acetone-d6): δ [ppm] = 0.95 (3H), 1.20–1.60 (10H), 3.40–4.00 (13H), 4.10–4.80 (10H), 6.50–7.50 (4H), 9.00 (1H)

[0419] 19F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0420] [Example 13]

[0421] The compound (AM) represented by the above formula (AM) was obtained by the method shown below (in formula (AM), mam, which represents the average degree of polymerization, is 6.2, and nam, which represents the average degree of polymerization, is 6.2).

[0422] First, 4'-hydroxyacetanilide was reacted with benzyl bromide to protect the phenolic hydroxyl group with the benzyl group, and then reacted with 1-bromohexane in the presence of sodium hydride. After deprotecting the benzyl group of the obtained compound with a hydrogen chloride / methanol reagent, it was reacted with epibromoethanol to synthesize the compound represented by the following formula (11-10).

[0423]

[0424] The compound (11-10) (5.38 g) represented by formula (11-10) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.8 g of compound (AM).

[0425] The resulting compound (AM) was subjected to [further processing]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0426] 1 ¹H-NMR (acetone-d6): δ [ppm] = 0.95 (3H), 1.20-1.60 (8H), 2.09 (3H), 3.40-4.00 (13H), 4.10-4.80 (10H), 6.50-7.50 (4H)

[0427] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0428] [Example 14]

[0429] The compound (AN) represented by the above formula (AN) was obtained by the method shown below (in formula (AN), man, which represents the average degree of polymerization, is 6.2, and nan, which represents the average degree of polymerization, is 6.2).

[0430] First, N-(2-hydroxyethyl)benzamide was reacted with epibromool to synthesize the compound represented by the following formula (11-11).

[0431]

[0432] The compound (11-11) (4.08 g) represented by formula (11-11) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.1 g of compound (AN).

[0433] The resulting compound (AN) was subjected to [further processing]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0434] 1 ¹H NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹⁵H), 4.10-4.80 (¹⁰H), 7.20-8.00 (¹⁵H), 8.50 (¹H)

[0435] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0436] [Example 15]

[0437] The compound (AO) represented by the above formula (AO) was obtained by the method shown below (in formula (AO), mao, which represents the average degree of polymerization, is 6.2, and nao, which represents the average degree of polymerization, is 6.2).

[0438] First, benzoic acid was reacted with 6-amino-1-hexanol, and the resulting compound was reacted with epibromool to synthesize the compound represented by the following formula (11-12).

[0439]

[0440] The compound (11-12) (5.12 g) represented by formula (11-12) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.6 g of compound (AO).

[0441] The obtained compound (AO) was subjected to 1 H-NMR and 19The structure was identified based on the following results obtained from F-NMR measurements.

[0442] 1 ¹H-NMR (acetone-d6): δ [ppm] = 1.20-1.40 (8H), 3.40-4.00 (15H), 4.10-4.80 (10H), 7.20-8.00 (5H), 8.50 (1H)

[0443] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0444] [Example 16]

[0445] The compound (AP) represented by the above formula (AP) was obtained by the method shown below (in formula (AP), map, which represents the average degree of polymerization, is 6.2, and nap, which represents the average degree of polymerization, is 6.2).

[0446] First, 4-hexylbenzoic acid was reacted with 2-aminoethanol, and the resulting compound was reacted with epibromoethanol to synthesize the compound represented by the following formula (11-13).

[0447]

[0448] The compound (11-13) (5.64 g) represented by formula (11-13) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.9 g of compound (AP).

[0449] The resulting compound (AP) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0450] 1 ¹H-NMR (acetone-d6): δ [ppm] = 0.86 (3H), 1.18-1.61 (8H), 2.56 (2H), 3.40-4.00 (15H), 4.10-4.80 (10H), 7.20-8.00 (5H), 8.50 (1H)

[0451] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0452] [Example 17]

[0453] The compound (AQ) represented by the above formula (AQ) was obtained by the method shown below (in formula (AQ), maq, representing the average degree of polymerization, is 6.2, and naq, representing the average degree of polymerization, is 6.2).

[0454] First, 4-hexyloxybenzoic acid was reacted with 2-aminoethanol, and the resulting compound was reacted with epibromoethanol to synthesize the compound represented by the following formula (11-14).

[0455]

[0456] The compound (11-14) (5.93 g) represented by formula (11-14) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 15.0 g of compound (AQ).

[0457] The resulting compound (AQ) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0458] 1 ¹H-NMR (acetone-d6): δ [ppm] = 0.94 (3H), 1.32-1.61 (8H), 3.40-4.00 (17H), 4.10-4.80 (10H), 7.20-8.00 (5H), 8.50 (1H)

[0459] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0460] [Example 18]

[0461] The compound (AR) represented by the above formula (AR) was obtained by the method shown below (in formula (AR), mar, which represents the average degree of polymerization, is 6.2, and nar, which represents the average degree of polymerization, is 6.2).

[0462] First, terephthalic acid was reacted with 2-aminoethanol, and the resulting compound was reacted with epibromoethanol to synthesize the compound represented by the following formula (11-15).

[0463]

[0464] The compound (11-15) (4.88 g) represented by formula (11-15) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.5 g of compound (AR).

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

[0466] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (15H), 4.10-4.80 (10H), 6.50-6.70 (1H), 7.60-8.70 (5H), 8.50 (1H)

[0467] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0468] [Example 19]

[0469] The compound (AS) represented by the above formula (AS) was obtained by the method shown below (in formula (AS), mas, which represents the average degree of polymerization, is 6.2, and nas, which represents the average degree of polymerization, is 6.2).

[0470] First, 3-hydroxypropionic acid was reacted with aniline and the resulting compound was reacted with epibromool to synthesize the compound represented by the following formula (11-16).

[0471]

[0472] The compound (11-16) (4.08 g) represented by formula (11-16) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.1 g of compound (AS).

[0473] The resulting compound (AS) was subjected to [processing / treatment]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0474] 1¹H-NMR (acetone-d6): δ [ppm] = 2.72 (2H), 3.40-4.00 (¹³H), 4.10-4.80 (¹⁰H), 7.20-8.00 (⁵H), 8.50 (¹H)

[0475] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0476] [Example 20]

[0477] The compound (AT) represented by the above formula (AT) was obtained by the method shown below (in formula (AT), mat, which represents the average degree of polymerization, is 6.2, and nat, which represents the average degree of polymerization, is 6.2).

[0478] First, 3-(benzyloxy)propionic acid was reacted with aniline, and then reacted with iodomethane in the presence of sodium hydride. The resulting compound was then subjected to contact hydrogenation in the presence of palladium on carbon, and then reacted with epibromoethanol to synthesize the compound represented by the following formulas (11-17).

[0479]

[0480] The compound (11-17) (4.34 g) represented by formula (11-17) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.2 g of compound (AT).

[0481] The resulting compound (AT) was subjected to [treatment / processing]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0482] 1 ¹H-NMR (acetone-d6): δ [ppm] = 2.72 (2H), 3.21 (3H), 3.40–4.00 (13H), 4.10–4.80 (10H), 7.20–8.00 (5H)

[0483] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0484] [Example 21]

[0485] The compound (AU) represented by the above formula (AU) was obtained by the method shown below (in formula (AU), mau, which represents the average degree of polymerization, is 6.2, and nau, which represents the average degree of polymerization, is 6.2).

[0486] First, 1 equivalent of 3,4-dihydro-2H-pyran was reacted with 1,6-hexanediol. The resulting compound was then reacted with epibromoethanol to synthesize the compound represented by formula (12-2).

[0487]

[0488] The compound (12-2) (3.50 g) represented by formula (12-2) was used instead of the compound (12-1) represented by formula (12-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.4 g of compound (AU).

[0489] The resulting compound (AU) was subjected to [processing / treatment]. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0490] 1 ¹H-NMR (acetone-d6): δ [ppm] = 1.20-1.80 (8H), 3.40-4.00 (11H), 4.10-4.80 (10H), 6.50-6.70 (1H), 7.00-8.10 (5H)

[0491] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0492] [Example 22]

[0493] The compound (AV) represented by the above formula (AV) was obtained by the method shown below (in formula (AV), mav, which represents the average degree of polymerization, is 6.2, and nav, which represents the average degree of polymerization, is 6.2).

[0494] First, the compound represented by formula (12-4) was synthesized by the method shown below. The primary hydroxyl group of 3-allyloxy-1,2-propanediol was protected with tert-butyldimethylsilyl, and the secondary hydroxyl group was protected with methoxymethyl. The tert-butyldimethylsilyl group was removed from the obtained compound, thereby synthesizing compound (12-3) represented by formula (12-3). The obtained compound (12-3) was reacted with 2-(2-chloroethoxy)tetrahydropyran, and the double bond was oxidized with m-chloroperoxybenzoic acid, thereby synthesizing compound (12-4) represented by formula (12-4).

[0495]

[0496] The compound (12-4) (4.34 g) represented by formula (12-4) was used instead of the compound (12-1) represented by formula (12-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.5 g of compound (AV).

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

[0498] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹⁴H), 4.10-4.80 (¹³H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0499] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0500] [Example 23]

[0501] The compound (AW) represented by the above formula (AW) was obtained by the method shown below (in formula (AW), maw, which represents the average degree of polymerization, is 6.2, and naw, which represents the average degree of polymerization, is 6.2).

[0502] First, 2-hydroxybenzamide was reacted with allyl glycidyl ether, and then the double bond was oxidized with m-chloroperoxybenzoic acid, thereby synthesizing the compound represented by the following formula (11-18).

[0503]

[0504] The compound (11-18) (4.93 g) represented by formula (11-18) was used instead of the compound (11-1) represented by formula (11-1) used in Example 1. Otherwise, the same operation as in Example 1 was performed to obtain 14.5 g of compound (AW).

[0505] The resulting compound (AW) was subjected to 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0506] 1 ¹H-NMR (acetone-d6): δ [ppm] = 3.40-4.00 (¹⁴H), 4.10-4.80 (¹³H), 6.50-6.70 (¹H), 7.00-8.10 (⁵H)

[0507] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0508] [Example 24]

[0509] The compound (AX) represented by the above formula (AX) was obtained by the method shown below (in formula (AX), max, which represents the average degree of polymerization, is 6.2, and nax, which represents the average degree of polymerization, is 6.2).

[0510] First, 3-buten-1-ol was reacted with 3,4-dihydro-2H-pyran. After protecting the hydroxyl group of 3-buten-1-ol with a tetrahydropyran group, the double bond was oxidized with m-chloroperoxybenzoic acid, thereby synthesizing the compound represented by the following formula (12-5).

[0511]

[0512] Using compound (12-5) (2.33 g) of formula (12-5) instead of compound (12-1) of formula (12-1) used in Example 23, the same operation as in Example 23 was performed to obtain 14.3 g of compound (AX).

[0513] The resulting compound (AX) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0514] 1¹H-NMR (acetone-d6): δ [ppm] = 1.40 (2H), 3.40-4.00 (12H), 4.10-4.80 (11H), 6.50-6.70 (1H), 7.00-8.10 (5H)

[0515] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0516] [Example 25]

[0517] The compound (AY) represented by the above formula (AY) was obtained by the method shown below (in formula (AY), may, which represents the average degree of polymerization, is 6.2, and nay, which represents the average degree of polymerization, is 6.2).

[0518] First, the compound represented by formula (12-7) was synthesized by the method shown below. 6-Hepten-1-ol was reacted with 3,4-dihydro-2H-pyran, and the hydroxyl group of 6-hepten-1-ol was protected with a tetrahydropyran group. The double bond was then oxidized with m-chloroperoxybenzoic acid, thereby synthesizing the compound represented by formula (12-6). The resulting compound (12-6) was reacted with allyl alcohol, and then with 3,4-dihydro-2H-pyran, where the secondary hydroxyl group was protected with a tetrahydropyran group. Finally, the double bond was oxidized with m-chloroperoxybenzoic acid, thereby synthesizing the compound (12-7) represented by formula (12-7).

[0519]

[0520] Using compound (12-7) (5.04 g) of formula (12-7) instead of compound (12-1) of formula (12-1) used in Example 1, otherwise the same operation as in Example 1 was performed to obtain 14.6 g of compound (AY).

[0521] The resulting compound (AY) was processed. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0522] 1 ¹H-NMR (acetone-d6): δ [ppm] = 1.20-1.80 (8H), 3.40-4.00 (12H), 4.10-4.80 (11H), 6.50-6.70 (1H), 7.00-8.10 (5H)

[0523] 19F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0524] [Example 26]

[0525] The compound (AZ) represented by the above formula (AZ) was obtained by the method shown below (in formula (AZ), maz, which represents the average degree of polymerization, is 6.2, and naz, which represents the average degree of polymerization, is 6.2).

[0526] First, the compound represented by formula (12-8) was synthesized by the method shown below. Compound (12-1) represented by formula (12-1) was reacted with 3-buten-1-ol, followed by reaction with 3,4-dihydro-2H-pyran, with the secondary hydroxyl group protected by a tetrahydropyran group. Finally, the double bond was oxidized using m-chloroperoxybenzoic acid, thereby synthesizing compound (12-8) represented by formula (12-8).

[0527]

[0528] Using compound (12-8) (5.07 g) of formula (12-8) instead of compound (12-1) of formula (12-1) used in Example 1, otherwise the same operation as in Example 1 was performed to obtain 14.6 g of compound (AZ).

[0529] The obtained compound (AZ) was subjected to 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0530] 1 ¹H-NMR (acetone-d6): δ [ppm] = 1.40 (2H), 3.40–4.00 (14H), 4.10–4.80 (13H), 6.50–6.70 (1H), 7.00–8.10 (5H)

[0531] 19 F-NMR (acetone-d6): δ [ppm] = -51.99 to -55.72 (12.4F), -78.48 (2F), -80.66 (2F), -89.16 to -91.14 (24.8F)

[0532] [Example 27]

[0533] The compound (BA) represented by the above formula (BA) was obtained by the method shown below (in formula (BA), nba, which represents the average degree of polymerization, is 6.2).

[0534] First, 4'-hydroxyacetylaniline was reacted with allyl glycidyl ether, and then the double bond was oxidized with m-chloroperoxybenzoic acid, thereby synthesizing the compound represented by the following formula (11-19).

[0535]

[0536] Use HOCH2CF2CF2O(CF2CF2CF2O) x A fluoropolyether (number average molecular weight of 1300 and molecular weight distribution of 1.1) (40.0 g) representing CF2CF2CH2OH (where x represents the average degree of polymerization of 6.2) was used instead of HOCH2CF2O (CF2CF2O) in Example 11. u (CF2O) v A fluoropolyether (number-average molecular weight of 1300 and molecular weight distribution of 1.1) representing CF2CH2OH (where u represents the average degree of polymerization of 6.2 and v represents the average degree of polymerization of 6.2) was used, and 3.81 g of compound (11-19) representing formula (12-1) was used instead of compound (12-1) representing formula (12-1) used in Example 11. Otherwise, the same operation as in Example 11 was performed to obtain 15.4 g of compound (BA).

[0537] The resulting compound (BA) was subjected to... 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0538] 1 ¹H-NMR (acetone-d6): δ [ppm] = 2.09 (6H), 3.40–4.00 (12H), 4.10–4.80 (11H), 6.50–7.50 (8H), 9.00 (2H)

[0539] 19 F-NMR (acetone-d6): δ [ppm] = -84.22 (24.8F), -86.40 (4F), -124.30 (4F), -130.08 (12.4F)

[0540] [Example 28]

[0541] The compound (BB) represented by the above formula (BB) was obtained by the method shown below (in formula (BB), nbb, which represents the average degree of polymerization, is 6.2).

[0542] Under a nitrogen atmosphere, HOCH2CF2CF2O(CF2CF2CF2O) was added to a 200mL round-bottom flask.x A fluoropolyether (number average molecular weight 1300, molecular weight distribution 1.1) represented by CF2CF2CH2OH (where x represents the average degree of polymerization of 6.2) (40.0 g), a compound represented by formulas (11-19) above (17.3 g), and t-BuOH (tert-butanol) (40.0 mL) were stirred at room temperature until homogeneous. Further, t-BuOK (potassium tert-butoxide) (1.04 g) was added to the above-mentioned flask, heated to 70°C, and stirred for 12 hours to allow the reaction to proceed.

[0543] The reaction product was then cooled to 25°C, water was added, and ethyl acetate was added as a solvent to extract the organic layer, followed by washing with water. Anhydrous sodium sulfate was added to the organic layer for dehydration, and the desiccant was filtered off. The filtrate was then concentrated. The residue was purified by silica gel column chromatography to obtain 34.4 g of compound (BB).

[0544] The resulting compound (BB) was processed. 1 H-NMR and 19 The structure was identified based on the following results obtained from F-NMR measurements.

[0545] 1 ¹H-NMR (acetone-d6): δ [ppm] = 2.09 (6H), 3.40–4.00 (15H), 4.10–4.80 (14H), 6.50–7.50 (8H), 9.00 (2H)

[0546] 19 F-NMR (acetone-d6): δ [ppm] = -84.22 (24.8F), -86.40 (4F), -124.30 (4F), -130.08 (12.4F)

[0547] Tables 1 and 2 show the R values ​​when the compounds (AA) to (BB) of Examples 1 to 28 obtained as described above are substituted into Formula (1). 1 (R 1 The terminal groups, structures, and aromatic hydrocarbons represented by [B]-[A] (c in formula (3-1), d and e in formula (3-2), R 2 The structure, [C]-[D] (f in equation (4-1), g and h in equation (4-2), R 3 (a, b, X in equation (2)) 1 ).

[0548] [Table 1]

[0549]

[0550] [Table 2]

[0551]

[0552] [Comparative Example 1]

[0553] The compound represented by the following formula (ZA) was synthesized using the method described in Patent Document 1.

[0554]

[0555] (In formula (ZA), mza, representing the average degree of polymerization, is 6.2, and nza, representing the average degree of polymerization, is 6.2.)

[0556] [Comparative Example 2]

[0557] The compound represented by the following formula (ZB) was synthesized using the method described in Patent Document 2.

[0558]

[0559] (In formula (ZB), mzb, representing the average degree of polymerization, is 6.2, and nzb, representing the average degree of polymerization, is 6.2.)

[0560] [Comparative Example 3]

[0561] The compound represented by the following formula (ZC) was synthesized using the method described in Patent Document 3. That is, in Example 1 of Patent Document 3, the compound represented by formula (11-8) was synthesized instead of glycidyl phenyl ether.

[0562]

[0563] (In formula (ZC), mzc, representing the average degree of polymerization, is 6.2, and nzc, representing the average degree of polymerization, is 6.2.)

[0564] [Comparative Example 4]

[0565] The compound represented by the following formula (ZD) was synthesized using the method described in Patent Document 4.

[0566]

[0567] (In formula (ZD), mzd, representing the average degree of polymerization, is 6.2, and nzd, representing the average degree of polymerization, is 6.2.)

[0568] [Comparative Example 5]

[0569] The compound represented by the following formula (ZE) was synthesized using the method described in Patent Document 5. That is, in Example 1 of Patent Document 5, the compound represented by formula (11-8) was synthesized instead of 4-methoxyglycidylphenyl ether.

[0570]

[0571] (In formula (ZE), nze, representing the average degree of polymerization, is 6.2.) [Comparative Example 6]

[0572] The compound represented by the following formula (ZF) was synthesized using the method described in Patent Document 2.

[0573]

[0574] (In formula (ZF), mzf, representing the average degree of polymerization, is 6.2, and nzf, representing the average degree of polymerization, is 6.2.)

[0575] [Comparative Example 7]

[0576] The compound represented by the following formula (ZG) was synthesized using the method described in Patent Document 2.

[0577]

[0578] (In formula (ZG), mzg, representing the average degree of polymerization, is 6.2, and nzg, representing the average degree of polymerization, is 6.2.)

[0579] [Comparative Example 8]

[0580] The compound (ZH) represented by the following formula (ZH) was synthesized using the method described in Patent Document 2.

[0581]

[0582] (In formula (ZH), mzh, representing the average degree of polymerization, is 6.2, and nzh, representing the average degree of polymerization, is 6.2.)

[0583] The number-average molecular weights (Mn) (number-average molecular weight of PFPE chains and number-average molecular weight of the whole molecule) and PFPE ratios (PFPE chain Mn / whole molecule Mn) of the compounds (AA) to (BB) and (ZA) to (ZH) obtained in Examples 1 to 28 and Comparative Examples 1 to 8 are shown in Table 3.

[0584] [Table 3]

[0585]

[0586] Next, a lubricant layer forming solution was prepared using the compounds obtained in Examples 1-28 and Comparative Examples 1-8 according to the method shown below. Then, using the obtained lubricant layer forming solution, a lubricant layer of the magnetic recording medium was formed according to the method shown below, thereby obtaining the magnetic recording media of Examples 1-28 and Comparative Examples 1-8.

[0587] [Solution for forming a lubricating layer]

[0588] The compounds obtained in Examples 1-28 and Comparative Examples 1-8 were dissolved in fluorinated solvent, specifically fluorinated solvent, in fluorinated solvent XF (trade name, manufactured by Mitsui Dupont Fluorokemica Co., Ltd.), with the film thickness when coated onto the protective layer being... The solution for forming a lubricating layer is prepared by diluting the compound with Vertebrate XF to a concentration of 0.001% to 0.01% by mass.

[0589] [Magnetic recording media]

[0590] An adhesion layer, a soft magnetic layer, a first base layer, a second base layer, a magnetic layer, and a protective layer were sequentially disposed on a substrate with a diameter of 65 mm. The protective layer was composed of carbon nitride.

[0591] On the protective layer of the substrate having each layer up to the protective layer, the lubricating layer forming solutions of Examples 1 to 28 and Comparative Examples 1 to 8 were applied by dip coating.

[0592] Then, the magnetic recording medium coated with the lubricant layer forming solution was placed in a constant temperature bath at 120°C and subjected to heat treatment for 10 minutes. This formed a lubricant layer on the protective layer, resulting in the magnetic recording media of Examples 1-28 and Comparative Examples 1-8.

[0593] For the magnetic recording media of Examples 1-28 and Comparative Examples 1-8 obtained as described above, the film thickness of the lubricating layer, the adhesion (bonding rate) between the lubricating layer and the protective layer, the adhesion characteristics test, the detachment characteristics test, and the smoothness (touchdown power) test were performed and evaluated using the methods shown below. The results are shown in Table 3.

[0594] [Measurement of Lubricating Layer Thickness]

[0595] The peak height of the CF vibrational stretching of the lubricating layer was measured using a Fourier transform infrared spectrophotometer (FT-IR, trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific). Then, the film thickness of the lubricating layer was calculated from the measured peak height using a correlation derived later.

[0596] [Methods for calculating correlations]

[0597] A disk was 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. On the protective layer of this disk... ( The film thicknesses at intervals () respectively form the lubricating layers.

[0598] Then, for each disk with a lubricating layer, the increase in film thickness, measured from the surface of the disk without a lubricating layer, was determined using an ellipsometer, and this increase was taken as the film thickness of the lubricating layer. Additionally, for each disk with a lubricating layer, the peak height during CF vibration and stretching was determined using FT-IR.

[0599] Then, the correlation between the peak height obtained by FT-IR and the film thickness of the lubricating layer obtained by ellipsometer is determined.

[0600] [Determination of the adhesion (bonding rate) between the lubricating layer and the protective layer]

[0601] For magnetic recording media with a lubricating layer, after measuring the film thickness of the lubricating layer using the method described above, washing was performed by immersing the medium in Virtue XF as a solvent for 10 minutes and then lifting it out. The immersion speed of the magnetic recording medium in the solvent was set to 10 mm / sec, and the lifting speed was set to 1.2 mm / sec. Then, the film thickness of the lubricating layer after solvent immersion (after washing) was measured using the same method as the lubricating layer film thickness measurement performed before washing.

[0602] Then, the film thickness of the lubricating layer before washing was denoted as α, and the film thickness of the lubricating layer after washing (after solvent impregnation) was denoted as β. The bond ratio of the lubricant was calculated from the ratio of α to β ((β / α) × 100 (%)). Using the calculated bond ratio, the adhesion between the lubricating layer and the protective layer was evaluated according to the criteria shown below.

[0603] The adhesion ratio can be used as an indicator of the bonding strength between the lubricating layer and the protective layer. If the adhesion between the lubricating layer and the protective layer is poor, some of the fluorinated ether compounds contained in the lubricating layer will dissolve into the polar XF and be washed away. Therefore, the film thickness of the lubricating layer becomes smaller after washing, and the adhesion ratio decreases.

[0604] Evaluation criteria for "adhesion (binding rate)"

[0605] ◎(Excellent): Combination rate of over 65%

[0606] 〇 (Good): Binding rate 60%–64%

[0607] △ (Qualified): Binding rate 40%–59%

[0608] × (Unqualified): Binding rate below 39%

[0609] [Adhesion Properties Test]

[0610] The magnetic recording medium and magnetic head were mounted on a spinstand and rotated under reduced pressure (approximately 250 torr) at room temperature, allowing the magnetic head to float at a fixed point for 10 minutes. Then, the surface of the magnetic head opposite the magnetic recording medium was analyzed using an ESCA (Electron Spectroscopy for Chemical Analysis) analyzer. The intensity (signal intensity (au)) of the fluorine peak obtained using the ESCA analyzer represents the amount of lubricant adhering to the magnetic head. The adhesion characteristics were evaluated using the obtained signal intensity of the fluorine peak according to the evaluation criteria shown below.

[0611] Evaluation Criteria for Adhesion Properties

[0612] ◎(Excellent): Signal strength below 160 (very low adhesion)

[0613] 〇 (Good): Signal strength is 161-300 (low adhesion).

[0614] △ (Qualified): Signal strength is 301-1000 (high adhesion amount)

[0615] × (Unacceptable): Signal strength above 1001 (extremely high adhesion amount)

[0616] [Shedding Characteristics Test]

[0617] A magnetic recording medium was mounted on a rotating frame and rotated at 10,000 rpm for 72 hours at 80°C. Before and after this operation, the film thickness of the lubricating layer at a radius of 20 mm from the center of the magnetic recording medium was measured using FT-IR, and the reduction rate of the lubricating layer thickness before and after the test was calculated. Using the calculated reduction rate of film thickness, the shedding characteristics were evaluated according to the evaluation criteria shown below.

[0618] Evaluation criteria for shedding characteristics

[0619] ◎(Excellent): Film thickness reduction rate is less than 2%

[0620] 〇 (Good): Film thickness reduction rate greater than 2% and less than 3%

[0621] △ (Qualified): Film thickness reduction rate greater than 3% and less than 9%

[0622] × (Unacceptable): Film thickness reduction rate greater than 9%

[0623] [Lubricant Smoothness (Ground Contact Power) Test]

[0624] Ground contact power (TDp) was measured as an evaluation index of the smoothness of the lubricating layer surface. TDp was measured using a write tester (DFH tester) as described below.

[0625] The magnetic recording medium being evaluated was rotated at 5400 rpm, with the magnetic head positioned relative to a point with a radius of 18 mm from the center. The heater power of the writing element (DFH element) of the magnetic head was gradually increased, causing thermal expansion of the DFH element due to the heat generated by the heater. The heater power at the point in time when the tip of the DFH element, protruding due to thermal expansion, came into contact with the lubricating layer of the magnetic recording medium was measured and recorded as TDp (in mW). The contact between the tip of the DFH element and the lubricating layer of the magnetic recording medium was detected using an acoustic emission (AE) sensor.

[0626] Generally, if the thickness of the lubricating layer becomes thinner, the TDp required for the DFH element to make contact with the surface of the lubricating layer increases. On the other hand, when comparing magnetic recording media with the same average film thickness, it can be seen that the greater the surface roughness of the lubricating layer, the greater the maximum height of the lubricating layer, and therefore the smaller the value of TDp.

[0627] "Evaluation Criteria for Smoothness"

[0628] ◎(Excellent): TDp value above 51.5mW (very small surface roughness)

[0629] 〇 (Good): TDp value is 51.0~51.4mW (small surface unevenness)

[0630] △ (Qualified): TDp value is 50.5~50.9mW (large surface unevenness)

[0631] × (Unacceptable): TDp value below 50.4mW (extremely uneven surface)

[0632] [Overall Evaluation]

[0633] The results of the adhesion (bonding rate) test between the lubricating layer and the protective layer, the adhesion characteristic test, the detachment characteristic test, and the smoothness (grounding power) test were comprehensively evaluated according to the evaluation criteria shown below.

[0634] Evaluation Criteria for Comprehensive Evaluation

[0635] ◎(Excellent): The evaluation of bonding rate, adhesion characteristics, shedding characteristics, and smoothness is all ◎(Excellent).

[0636] 〇 (Good): The evaluation of bonding rate, adhesion characteristics, shedding characteristics and smoothness is ◎ (Excellent) or 〇 (Good), and more than one of them is 〇 (Good).

[0637] △ (Pass): △ (Pass) is awarded for one or more of the following evaluation criteria: bonding rate, adhesion characteristics, shedding characteristics, and smoothness. × (Fail) is not awarded for any of these criteria.

[0638] × (Unacceptable): If one or more of the following evaluation criteria are met (unacceptable): bonding rate, adhesion characteristics, shedding characteristics, or smoothness, the result is × (unacceptable).

[0639] As shown in Table 3, for the magnetic recording media of Examples 1 to 28, which use the fluorinated ether compound represented by Formula (1) to form a lubricating layer, the evaluation of adhesion rate, adhesion characteristics, detachment characteristics, and smoothness is all ◎ (excellent) or ○ (good), and the overall evaluation is ◎ (excellent) or ○ (good). That is, the magnetic recording media of Examples 1 to 28 have a lubricating layer that is not prone to adhesion and detachment and has good adhesion and smoothness to the protective layer.

[0640] In contrast, the magnetic recording media of Comparative Examples 1 to 8 showed poorer evaluation results in terms of binding rate, adhesion characteristics, shedding characteristics, and smoothness compared to the magnetic recording media of Examples 1 to 28.

[0641] More specifically, the results of Comparative Example 1, which used a compound without an amide bond, the results of Comparative Example 2, which used a compound without an aromatic hydrocarbon, and the results of Comparative Example 3, which used R in formula (1), were compared. 1 Examples 1, 5, 6, 8–14 of compounds containing a carbonyl carbon atom or nitrogen atom of an amide bond directly bonded to an aromatic hydrocarbon group confirmed that: by making R in formula (1) 1 A group consisting of a carbonyl carbon atom or nitrogen atom containing an amide bond directly bonded to an aromatic hydrocarbon results in a better evaluation of binding rate, adhesion properties, shedding properties, and smoothness.

[0642] Therefore, it is inferred that in order to obtain a magnetic recording medium with a comprehensive evaluation of ◎ (excellent) or ○ (good), a fluorinated ether compound represented by formula (1) must be used as the material of the lubricating layer, in which R 1 The carbonyl carbon atom or nitrogen atom of the amide bond is directly bonded to the aromatic hydrocarbon to form the same plane.

[0643] Furthermore, both Comparative Example 3 and Example 11 used compounds with terminal groups consisting of carbonyl carbon atoms or nitrogen atoms containing amide bonds directly bonded to aromatic hydrocarbons. However, as shown in Table 3, significant differences were observed in the evaluation results of binding rate, adhesion characteristics, detachment characteristics, and smoothness between Comparative Example 3 and Example 11. This is presumably because, in the magnetic recording medium of Comparative Example 3, a compound with a vicinal diol structure was used, resulting in the presence of hydroxyl groups in the lubricating layer that did not participate in the adsorption with the protective layer.

[0644] The magnetic recording media of Comparative Examples 4, 6 to 8 did not use compounds with terminal groups consisting of carbonyl carbon atoms or nitrogen atoms containing amide bonds directly bonded to aromatic hydrocarbons. Therefore, as shown in Table 3, the inferred binding rate, adhesion characteristics, shedding characteristics, and smoothness evaluation results were worse than those of the magnetic recording media of Examples 1 to 28.

[0645] The magnetic recording medium of Comparative Example 5 used a compound containing fewer than 3 hydroxyl groups in its molecule. Therefore, it was inferred that the hydroxyl groups in the fluorinated ether compound had insufficient adsorption force on the protective layer, and the evaluation results of binding rate, adhesion characteristics, shedding characteristics, and smoothness were worse than those of the magnetic recording media of Examples 1 to 28.

[0646] Industry availability

[0647] By using a lubricant for magnetic recording media containing the fluorinated ether compound of the present invention, a lubricating layer that is not prone to adhesion and detachment and provides good adhesion and smoothness to the protective layer can be formed.

[0648] Explanation of reference numerals in the attached figures

[0649] 10···Magnetic recording medium, 11···Substrate, 12···Adhesion layer, 13···Soft magnetic layer, 14···First base layer, 15···Second base layer, 16···Magnetic layer, 17···Protective layer, 18···Lubricating layer.

Claims

1. A fluorinated ether compound, characterized in that, It is represented by the following formula (1), R 1 -[B]-[A]-O-CH2-R 2 -CH2-O-[C]-[D]-R 3 (1) In equation (1), R 1 R represents any structure represented by equations (5-1) to (5-5) below; 2 Represented by the following equation (8-1); R 3 It is represented by the following formula (2); in formula (2), a represents an integer from 2 to 6, and b represents 0 or 1; X 1 X is a hydrogen atom or any structure represented by the following formulas (5-1) to (5-5). 1 With R 1 They can be the same or different; in equation (1), [A] is represented by the following equation (3-1); in equation (3-1), c is an integer from 0 to 3; in equation (1), [B] is represented by the following equation (3-2); in equation (3-2), d is an integer from 0 to 3, and e is an integer from 2 to 5; where the sum of c in equation (3-1) and d in equation (3-2) is 1 to 3; in equation (1), [A] and [B] can be interchanged; In equation (1), [C] is represented by equation (4-1) below; f in equation (4-1) is an integer from 0 to 3; in equation (1), [D] is represented by equation (4-2) below; g in equation (4-2) is an integer from 0 to 3, and h is an integer from 2 to 5; wherein, the sum of f in equation (4-1) and g in equation (4-2) is 1 to 3; [C] and [D] in equation (1) can be interchanged; [C] is directly bonded to R 3 In the case of R 3 It is not a hydrogen atom; the number of hydroxyl groups in formula (1) is 3 or more, R 1 and R 3 The number of hydroxyl groups in each is 0 or 1. ， In equations (5-1) to (5-3), X 2 It consists of one or more groups represented by formula (6-1) or (6-2). In equations (5-4) and (5-5), Y 5 It is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; L represents an integer from 1 to 6; Z is any one or more selected from hydrogen atoms, alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, and groups represented by formula (6-1) or (6-2). In equation (6-1), Y 1 and Y 2 Each is independently a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a Y atom. 1 With Y 2 Any of the ring structures formed by mutual bonding; the total number of carbon atoms contained in formula (6-1) is 1 to 8. In equation (6-2), Y 3 Y is an alkyl group having 1 to 7 carbon atoms. 4 It can be a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; it can also be Y. 3 With Y 4 A ring structure formed by mutual bonding; the total number of carbon atoms in formula (6-2) is 2~8. -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 - (8-1) In equation (8-1), w2, w3, w4, and w5 represent the average degree of polymerization, each independently representing 0 to 30; excluding the case where all of w2, w3, w4, and w5 are simultaneously 0; w1 and w6 represent the average quantity of CF2, each independently representing 1 to 3; the order of repeating units in equation (8-1) is not particularly restricted.

2. The fluorinated ether compound according to claim 1, wherein R in formula (1) 1 -[B]-[A]-and-[C]-[D]-R 3 They are the same.

3. The fluorinated ether compound according to claim 1, wherein X in formula (2) 1 It is a hydrogen atom.

4. The fluorinated ether compound according to claim 1, wherein -[C]-[D]-R in formula (1) 3 For any of the following equations (7-1) to (7-3), In equation (7-1), i represents 1 or 2, and j represents an integer from 1 to 5. In equation (7-2), k represents an integer from 2 to 5, t represents 0 or 1, and p represents an integer from 1 to 5. In equation (7-3), q represents 0 or 1, r represents an integer from 1 to 5, and s represents an integer from 1 to 4.

5. The fluorinated ether compound according to claim 1 or 2, wherein R in formula (1) 2 For any of the following equations (8-2) to (8-5), -CF2O-(CF2CF2O) u -(CF2O) v -CF2- (8-2) In equation (8-2), u and v represent the average degree of polymerization, each ranging from 0 to 30; where, If u or v is 0.1 or higher, -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 - (8-3) In equation (8-3), w8 and w9 represent the average degree of polymerization, each independently ranging from 0.1 to 30; w7 and w10 represent the average amount of CF2, each independently ranging from 1 to 2. -CF2CF2O-(CF2CF2CF2O) x -CF2CF2- (8-4) In equation (8-4), x represents the average degree of polymerization, and denoted as 0.1~30. -CF2CF2CF2O-(CF2CF2CF2CF2O) y -CF2CF2CF2- (8-5) In equation (8-5), y represents the average degree of polymerization and is expressed as 0.1~30.

6. The fluorinated ether compound according to claim 1 or 2, wherein the number average molecular weight is in the range of 500 to 10,000.

7. A lubricant for magnetic recording media, characterized in that, It comprises any one of the fluorinated ether compounds according to claims 1 to 6.

8. A magnetic recording medium, characterized in that, It is a magnetic recording medium having at least a magnetic layer, a protective layer and a lubricating layer sequentially disposed on a substrate, wherein the lubricating layer comprises a fluorinated ether compound as described in any one of claims 1 to 6.

9. The magnetic recording medium according to claim 8, wherein the average film thickness of the lubricating layer is 0.5 nm to 2.0 nm.

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