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

Abstract

A fluorine-containing ether compound represented by formula (1). (1) R1-O-R2-CH2-R3-CH2-R4-R5 (in which R3 is a perfluoropolyether chain, R1 is a C2–8 alkenyl group or a C3–8 alkynyl group, R2 and R4 are each independently a bivalent linking group that includes at least one hydroxyl group, and -R5 is a group that is represented by formula (2)). (2) -O-(CH2)g-N-R6R7 (in which g is an integer that is 2 or 3, R6 and R7 are identical or different saturated aliphatic groups, and R6 and R7 may form a ring structure with a nitrogen atom).

Description

[Technical Field]

[0001] The present invention relates to a fluorine-containing ether compound, a lubricant for a magnetic recording medium, and a magnetic recording medium. This application claims priority based on Japanese Patent Application No. 2020-139604, filed on August 20, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] In order to increase the recording density in magnetic recording and reproducing devices, development of magnetic recording media suitable for high recording densities is underway. Conventional magnetic recording media have a recording layer formed on a substrate, and a protective layer made of carbon or the like formed on the recording layer. The protective layer protects the information recorded on the recording layer and improves the sliding properties of the magnetic head.

[0003] However, simply providing a protective layer on the recording layer does not provide sufficient durability for the magnetic recording medium, so a lubricating layer is generally formed by applying a lubricant to the surface of the protective layer. As lubricants used in forming the lubricating layer of magnetic recording media, for example, those containing compounds having polar groups such as hydroxyl groups or amino groups at the end of a fluorine-based polymer having a repeating structure containing CF2 have been proposed.

[0004] For example, Patent Document 1 discloses a fluoropolyether compound having an amino alcohol group at the molecular end. Patent Document 2 discloses a fluorine-containing ether compound in which an alkenyl or alkynyl group is bonded to one end of a perfluoropolyether chain and a heterocyclic group is bonded to the other end. Patent Document 3 discloses a fluoroether compound having hydroxyl-containing amine groups at both molecular ends. Patent Document 4 discloses a perfluoropolyether-based liquid lubricant having an amine functional group at at least one of the chain molecular ends. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-131083 [Patent Document 2] International Publication No. 2019 / 087548 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-225572 [Patent Document 4] Patent No. 4099860 [Patent Document 5] Japanese Patent Application Publication No. 62-57418 [Patent Document 6] Japanese Patent Application Publication No. 2019-67468 [Patent Document 7] International Publication No. 2019 / 054148 Summary of the Invention [Problem to be solved by the invention]

[0006] In magnetic recording and reproducing devices, there is a demand for an even smaller flying height of the magnetic head, which in turn requires a thinner lubricating layer in the magnetic recording medium. However, reducing the thickness of the lubricating layer generally reduces the coverage of the lubricating layer, which tends to reduce the wear resistance of the magnetic recording medium. Furthermore, conventional lubricating layers have insufficient heat resistance, and there has been a demand for improved heat resistance.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluorine-containing ether compound suitable as a material for a lubricant for a magnetic recording medium, which can form a lubricating layer having excellent wear resistance and heat resistance. Another object of the present invention is to provide a lubricant for magnetic recording media which contains the fluorine-containing ether compound of the present invention and is capable of forming a lubricating layer having excellent wear resistance and heat resistance. Another object of the present invention is to provide a magnetic recording medium having a lubricating layer containing the fluorinated ether compound of the present invention, which can have a thin lubricating layer and has excellent wear resistance and heat resistance. [Means for solving the problem]

[0008] A first aspect of the present invention provides the following fluorine-containing ether compound: [1] A fluorine-containing ether compound represented by the following formula (1): R 1 -OR 2 -CH2-R 3 -CH2-R 4 -R 5 (1) (In formula (1), R 3 is a perfluoropolyether chain; R 1 is an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 3 to 8 carbon atoms; R 2 , R 4 are each independently a divalent linking group containing one or more hydroxyl groups; -R 5 is a group represented by the following formula (2): -O-(CH2) g -NR 6 R 7 (2) (In formula (2), g is an integer of 2 or 3; R 6 and R 7 are the same or different saturated aliphatic groups; R 6 and R 7 may form a ring structure together with the nitrogen atom.

[0009] The compound according to the first aspect of the present invention preferably includes the features described in the following items [2] to

[11] . It is also preferable to combine two or more of these features. [2] -R in the formula (1) 2 The fluorine-containing ether compound according to [1], wherein - is represented by the following formula (3): -((CH2) a -O) z -[X]-[Y]- (3) (In formula (3), a represents an integer of 1 to 3, z represents 0 or 1; [X] is represented by the following formula (X), [Y] is represented by the following formula (Y), and the bonding order of [X] and [Y] may be reversed; however, the sum of c in formula (X) and e in formula (Y) is 1 or 2.)

[0010] [ka] (In formula (X), b is an integer of 1 to 3, and c is an integer of 0 to 2.) (In formula (Y), d is an integer of 2 to 3, and e is an integer of 0 to 2.)

[0011] [3] -R in the formula (1) 4 The fluorine-containing ether compound according to [1] or [2], wherein - is represented by the following formula (4):

[0012] [ka] (In formula (4), f is an integer of 1 to 2.)

[0013] [4] R 2 and the hydroxyl group contained in the R 4 The fluorine-containing ether compound according to any one of [1] to [3], wherein the total number of hydroxyl groups contained in

[0014] [5] R in the formula (2) 6 and R 7 are each independently a saturated aliphatic group having 1 to 4 carbon atoms, or R 6 and R 7 The fluorine-containing ether compound according to any one of [1] to [4], wherein the nitrogen atom is linked to the fluorine-containing ether compound. [6] -NR in the formula (2) 6 R 7 The fluorine-containing ether compound according to any one of [1] to [4], wherein is a dimethylamino group or a diethylamino group. [7] -NR in the formula (2)6 R 7 The fluorine-containing ether compound according to any one of [1] to [4], wherein is any one group selected from a pyrrolidine group, a piperidine group, a morpholine group, and a hexamethyleneimine group.

[0015] [8] R in the formula (1) 1 The fluorine-containing ether compound according to any one of [1] to [7], wherein is any one group selected from a vinyl group, an allyl group, a 3-butenyl group, a 4-pentenyl group and a propargyl group.

[0016] [9] R 3 is any one of the following formulae (5) to (7): -CF2O-(CF2CF2O) h -(CF2O) i -CF2- (5) (In formula (5), h and i represent the average degree of polymerization and each represents 0 to 30; however, h and i cannot be 0 at the same time.) -CF(CF3)-(OCF(CF3)CF2) j -OCF(CF3)- (6) (In formula (6), j represents the average degree of polymerization and is 0.1 to 30.) -CF2CF2O-(CF2CF2CF2O) k -CF2CF2- (7) (In formula (7), k represents the average degree of polymerization and is 0.1 to 30.)

[0017]

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

[0018]

[11] The fluorine-containing ether compound according to [1], wherein the compound represented by formula (1) is any one of compounds represented by the following formulas (A), (B), (E), (F), and (I):

[0019] [ka] (In formula (A), ma and na represent the average degree of polymerization, ma representing 1 to 30, and na representing 0 to 30.) (In formula (B), mb and nb represent the average degree of polymerization, mb represents 1 to 30, and nb represents 0 to 30.) (In formula (E), me represents the average degree of polymerization, and me represents 0.1 to 30.) (In formula (F), mf represents the average degree of polymerization, and mf represents 0.1 to 30.) (In formula (I), pi represents the average degree of polymerization, and pi represents 0.1 to 30.)

[0020] A second aspect of the present invention provides the following lubricant:

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

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

[13] A magnetic recording medium having at least a magnetic layer, a protective layer, and a lubricating layer sequentially provided on a substrate, A magnetic recording medium, wherein the lubricating layer contains the fluorine-containing ether compound according to any one of [1] to

[11] .

[14] The magnetic recording medium according to

[13] , wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm. [Effects of the Invention]

[0021] The fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is therefore suitable as a material for a lubricant for a magnetic recording medium. The lubricant for magnetic recording media of the present invention contains the fluorine-containing ether compound of the present invention, and therefore can form a lubricating layer having excellent wear resistance and heat resistance. The magnetic recording medium of the present invention is provided with a lubricating layer having excellent wear resistance and heat resistance, so that the thickness of the lubricating layer can be made thin, and the magnetic recording medium has excellent reliability and durability. [Brief explanation of the drawings]

[0022] [Figure 1]1 is a schematic cross-sectional view showing a preferred embodiment of a magnetic recording medium of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] In order to solve the above problems, the present inventors have conducted extensive research as described below. As a result, it was found that compounds having alkenyl or alkynyl groups at the end of the perfluoropolyether chain can form lubricating layers with excellent wear resistance. However, the lubricating layers formed using these compounds had insufficient heat resistance. This is presumably because compounds having alkenyl or alkynyl groups are easily oxidized under heat treatment conditions. More specifically, when the alkenyl and / or alkynyl groups in the lubricating layer are oxidized under heat treatment conditions, oxidative decomposition products are generated. The generated oxidative decomposition products cannot remain on the magnetic recording medium rotating at high speed inside a hard disk drive. Therefore, it is presumed that high-speed rotation of the magnetic recording medium reduces the coverage of the lubricating layer and deteriorates the wear resistance of the magnetic recording medium.

[0024] Therefore, the present inventors have conducted further studies to suppress the thermal decomposition of the alkenyl or alkynyl group contained in the fluorine-containing ether compound. As a result, they found that a fluorine-containing ether compound in which the first end of the perfluoropolyether chain is an alkenyl group or an alkynyl group and the second end is a tertiary amine group linked to two or three methylene groups is sufficient.And they confirmed that in such a fluorine-containing ether compound, the tertiary amine suppresses the thermal decomposition of the alkenyl group or the alkynyl group, so that excellent heat resistance can be obtained.Furthermore, they confirmed that a lubricating layer containing this fluorine-containing ether compound can obtain excellent wear resistance, and thus they conceived the present invention.

[0025] Preferred examples of the fluorine-containing ether compound, lubricant for magnetic recording media (hereinafter sometimes abbreviated as "lubricant"), and magnetic recording media of the present invention will be described in detail below. Note that the present invention is not limited to the following embodiments. For example, the present invention is not limited to the following examples, and additions, omissions, substitutions, or changes can be made to the number, amount, ratio, composition, type, position, material, configuration, etc., within the scope of the present invention.

[0026] [Fluorine-containing ether compounds] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1). R 1 -OR 2 -CH2-R 3 -CH2-R 4 -R 5 (1) (In formula (1), R 3 is a perfluoropolyether chain; R 1 is an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 3 to 8 carbon atoms; R 2 , R 4 are each independently a divalent linking group containing one or more hydroxyl groups; -R 5 is a group represented by the following formula (2): -O-(CH2) g -NR 6 R 7 (2) (In formula (2), g is an integer of 2 or 3; R 6 and R 7 are the same or different saturated aliphatic groups; R 6 and R 7 may form a ring structure together with the nitrogen atom.

[0027] (R 1 an alkenyl group or alkynyl group represented by In the fluorine-containing ether compound represented by the above formula (1), R 1 is an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 3 to 8 carbon atoms. In the fluorine-containing ether compound of this embodiment, R 1and an alkenyl or alkynyl group in R 2 The hydroxyl group (—OH) in the lubricating layer containing the hydroxyl group exhibits good interaction with the protective layer. 1 The alkenyl group having 2 to 8 carbon atoms or the alkynyl group having 3 to 8 carbon atoms can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound.

[0028] R 1 is an alkenyl group having 2 to 8 carbon atoms, R 1 is a group having one carbon-carbon double bond. 1 When R is an alkenyl group, if the alkenyl group has 8 or less carbon atoms, R 1 The double bond of and R 2 This results in an appropriate distance between the fluorine-containing ether compound represented by formula (1) and the hydroxyl group of the lubricating layer containing the fluorine-containing ether compound, and the lubricating layer exhibits good interaction with the protective layer.

[0029] R 1 The alkenyl group having 2 to 8 carbon atoms is not particularly limited, and examples thereof include vinyl, allyl, crotyl, butenyl, beta-methallyl, methylbutenyl, pentenyl, hexenyl, heptenyl, and octenyl. Among these, alkenyl groups having 2 to 5 carbon atoms are preferred because they provide a lubricating layer that exhibits good affinity with the protective layer of the magnetic recording medium. Specifically, vinyl, allyl, 3-butenyl, and 4-pentenyl groups are preferred, with allyl and 3-butenyl being particularly preferred. 1 is an alkenyl group having 3 or more carbon atoms, the double bond is preferably located at the extreme end of the fluorine-containing ether compound, since this results in a fluorine-containing ether compound that can provide a lubricating layer that exhibits better interaction with the protective layer of the magnetic recording medium.

[0030] R 1 is an alkynyl group having 3 to 8 carbon atoms, R 1 is a group having one carbon-carbon triple bond.1 When R is an alkynyl group, if the alkynyl group has 8 or less carbon atoms, R 1 The triple bond of and R 2 This results in an appropriate distance between the fluorine-containing ether compound represented by formula (1) and the hydroxyl group of the lubricating layer containing the fluorine-containing ether compound, and the lubricating layer exhibits good interaction with the protective layer.

[0031] R 1 The alkynyl group having 3 to 8 carbon atoms is not particularly limited, and examples thereof include 1-propynyl, propargyl, butynyl, methylbutynyl, pentynyl, methylpentynyl, hexynyl, methylhexynyl, heptynyl, and octynyl groups. Among these, alkynyl groups having 3 to 5 carbon atoms are preferred because they provide a lubricating layer that exhibits good affinity with the protective layer of the magnetic recording medium. Specifically, 1-propynyl, propargyl, butynyl, and pentynyl groups are preferred, with propargyl being particularly preferred. The alkynyl group may also be in a form containing an alkenyl group in the molecule, such as a vinylpentynyl group. R 1 is an alkynyl group having 3 or more carbon atoms, the resulting fluorine-containing ether compound provides a lubricating layer that exhibits better interaction with the protective layer of the magnetic recording medium, so it is preferable that the triple bond be located at the extreme end of the fluorine-containing ether compound.

[0032] (R 2 a divalent linking group represented by R in Equation (1) 2 is a divalent linking group containing one or more hydroxyl groups. 2 The number of hydroxyl groups contained in R is preferably 1 or 2. 2 contains one or more hydroxyl groups, when a lubricating layer is formed on a protective layer using a lubricant containing the fluorine-containing ether compound of this embodiment, the lubricating layer can adhere appropriately to the protective layer. Therefore, the lubricating layer containing the fluorine-containing ether compound of this embodiment has good affinity with the protective layer and has excellent wear resistance.

[0033] -R in the formula (1) 2 - is preferably represented by the following formula (3). -((CH2) a -O) z -[X]-[Y]- (3) (In formula (3), a represents an integer of 1 to 3, z represents 0 or 1; [X] is represented by the following formula (X), [Y] is represented by the following formula (Y), and the bonding order of [X] and [Y] may be reversed; however, the sum of c in formula (X) and e in formula (Y) is 1 or 2.)

[0034] [ka] (In formula (X), b is an integer of 1 to 3, and c is an integer of 0 to 2.) (In formula (Y), d is an integer of 2 to 3, and e is an integer of 0 to 2.)

[0035] In formula (3), a is an integer of 1 to 3, and z is 0 or 1. When a and z are within this range, R 1 Intramolecular aggregation of the alkenyl or alkynyl group in the alkyl group (X) and / or the hydroxyl group in (Y) can be prevented. 2 In the lubricating layer containing the fluorine-containing ether compound represented by formula (3), R 1 an alkenyl or alkynyl group in R 2 The hydroxyl group (-OH) in the protective layer exhibits good interaction with the protective layer. Therefore, the lubricating layer has a high coverage and excellent wear resistance. In addition, since "a" in formula (3) is an integer of 3 or less and "z" is 0 or 1, R 2 The chain structure in the middle is too long, which increases the mobility of the molecules, 1 an alkenyl or alkynyl group in R 2 Therefore, the adhesion of the hydroxyl groups in the protective layer to the protective layer is not impaired.

[0036] In the formula (X) in the above formula (3), b is an integer of 1 to 3. If b is 3 or less, the proportion of carbon atoms in the molecule becomes too high, which increases the hydrophobicity of the molecule, and R 1 an alkenyl or alkynyl group in R 2 In addition, since b in formula (X) is an integer of 1 to 3, the adhesion between the hydroxyl groups in formula (X) and the protective layer does not become difficult to obtain due to excessive molecular motion. Furthermore, R 2 When there is one hydroxyl group contained in formula (X), when c in formula (X) is 1 and b is an integer of 1 to 3, R 2 The hydroxyl groups contained in R are less susceptible to the influence of surrounding atoms, making it easier to achieve adhesion to the protective layer. 2 When there are two hydroxyl groups contained in R, and b is an integer of 1 to 3, 2 The distance between the hydroxyl groups in the molecule is within an appropriate range (the number of atoms between the two hydroxyl groups is 5 to 9), which prevents intramolecular aggregation.

[0037] In the formula (3), d in the formula (Y) is an integer of 2 to 3. If d is 3 or less, the proportion of carbon atoms in the molecule becomes too high, which increases the hydrophobicity of the molecule, and R 1 an alkenyl or alkynyl group in R 2 In addition, since d in formula (Y) is an integer of 2 to 3, the adhesion between the hydroxyl groups in formula (Y) and the protective layer does not become difficult to obtain due to excessive molecular motion. Furthermore, R 2 When there is one hydroxyl group contained in formula (Y), when e in formula (Y) is 1 and d is an integer of 2 to 3, R 2 The hydroxyl groups contained in R are less susceptible to the influence of surrounding atoms, making it easier to achieve adhesion to the protective layer. 2 When there are two hydroxyl groups contained in R, and d is an integer of 2 to 3, 2 The distance between the hydroxyl groups in the molecule is within an appropriate range (the number of atoms between the two hydroxyl groups is 5 to 9), which prevents intramolecular aggregation.

[0038] In the above formula (3), c in formula (X) is an integer of 0 to 2, and e in formula (Y) is an integer of 0 to 2, and the sum of c and e is 1 or 2. Since c and e are within this range, -R 2 - is expressed by equation (3), R 2 has one or two hydroxyl groups. When the sum of c and e is 1 or more, when a lubricating layer is formed on a protective layer using a lubricant containing the fluorine-containing ether compound of this embodiment, R 2 The interaction between the hydroxyl group of R and the protective layer is obtained. 2 The interaction between the hydroxyl groups of the protective layer and the hydroxyl groups of the protective layer becomes more pronounced.

[0039] In addition, since the sum of c and e in the above formula (3) is 2 or less, R 2 The polarity of the fluorine-containing ether compound does not become too high due to the presence of too many hydroxyl groups, and therefore the occurrence of pickup in which the fluorine-containing ether compound adheres to the magnetic head as foreign matter (smear) can be suppressed.

[0040] (R 4 a divalent linking group represented by R in Equation (1) 4 is a divalent linking group containing one or more hydroxyl groups. 4 The number of hydroxyl groups contained in R is preferably 1 or 2. 4 contains one or more hydroxyl groups, when a lubricating layer is formed on a protective layer using a lubricant containing the fluorine-containing ether compound of this embodiment, R 4 The lubricating layer can adhere properly to the protective layer due to the interaction between the hydroxyl groups of the fluorine-containing ether compound and the protective layer. Therefore, the lubricating layer containing the fluorine-containing ether compound of this embodiment has good affinity with the protective layer and excellent abrasion resistance. -R in the formula (1) 4 - is preferably represented by the following formula (4).

[0041] [ka] (In formula (4), f is an integer of 1 to 2.)

[0042] In formula (4), f is an integer between 1 and 2. Therefore, R 4 When is expressed by equation (4), R 4 has one or two hydroxyl groups. Since f is 2 or less, R 4 The polarity of the fluorine-containing ether compound does not become too high due to the presence of too many hydroxyl groups, and therefore the occurrence of pickup in which the fluorine-containing ether compound adheres to the magnetic head as foreign matter (smear) can be suppressed.

[0043] R in Equation (1) 2 , R 4 are each independently a divalent linking group containing one or more hydroxyl groups. 2 and R 4 The total number of hydroxyl groups contained in R is 2 or more. 2 and R 4 The total number of hydroxyl groups contained in R is preferably 3 or more, and more preferably 3 or 4. 2 and R 4 When the total number of hydroxyl groups contained in is 3 or 4, the lubricating layer containing the fluorine-containing ether compound of this embodiment is likely to have appropriate adhesion to the protective layer.

[0044] (R 5 (a group having a tertiary amine represented by formula (2)) -R in formula (1) 5 is a group represented by the following formula (2). -O-(CH2) g -NR 6 R 7 (2) (In formula (2), g is an integer of 2 or 3.)

[0045] The group represented by formula (2) is a tertiary amine (—NR 6 R 7). The unshared electron pair of the nitrogen atom forming the tertiary amine exhibits good interaction with the protective layer in a lubricating layer containing the fluorinated ether compound represented by formula (1), thereby enhancing adhesion to the protective layer. Furthermore, the tertiary amine contained in the group represented by formula (2) has the function of capturing radicals under heat treatment conditions. This allows the fluorinated ether compound of this embodiment to have excellent heat resistance. Furthermore, a lubricating layer containing the fluorinated ether compound of this embodiment, which has excellent heat resistance, can maintain an appropriate coverage rate and has good wear resistance.

[0046] R 5 The nitrogen atom of the tertiary amine contained in the alkylene group (-(CH2) g -) in formula (2). g - is a divalent linking group having an ether bond, and g in formula (2) is an integer of 2 or 3. Therefore, in the fluorine-containing ether compound represented by formula (1), the nitrogen atom in the tertiary amine and R 4 The distance between the hydroxyl group (-OH) in the lubricant and the fluorine-containing ether compound represented by formula (1) is appropriate. Therefore, the fluorine-containing ether compound is less likely to aggregate intramolecularly and is more likely to be arranged in a uniformly extending state on the protective layer by spreading in the surface direction. Therefore, even if the lubricant containing the fluorine-containing ether compound represented by formula (1) is thin, it can cover the surface of the protective layer with a high coverage rate and form a lubricant layer with excellent wear resistance.

[0047] On the other hand, if g in formula (2) is less than 2, the resulting fluorine-containing ether compound is prone to intramolecular aggregation. As a result, when the lubricating layer containing this compound is thinned, it does not achieve sufficient coverage and therefore does not achieve sufficient wear resistance. Furthermore, if g in formula (2) is more than 3, the alkylene group is too long, which increases the mobility of the molecular terminals, making it difficult to achieve adhesion to the tertiary amine protective layer.

[0048] In addition, in the fluorine-containing ether compound represented by formula (1), the ether bond (—O—) in formula (2) forms R 4 is a tertiary amine (-NR 6 R 7) is bonded to a group containing the fluorine-containing ether compound, the molecular structure has moderate flexibility. Therefore, in the lubricating layer containing the fluorine-containing ether compound represented by formula (1), the R 4 and tertiary amines (-NR 6 R 7 ) interacts favorably with the protective layer disposed in contact with the lubricating layer. Therefore, the lubricating layer containing the fluorine-containing ether compound is easily adsorbed to the protective layer, and has excellent adhesion to the protective layer and excellent wear resistance.

[0049] In the fluorine-containing ether compound represented by formula (1), the structure of the tertiary amine contained in formula (2) can be appropriately selected depending on the performance required of a lubricant containing the fluorine-containing ether compound. R in equation (2) 6 and R 7 are the same or different saturated aliphatic groups. The saturated aliphatic groups may be linear, branched, or cyclic. 6 and R 7 may form a ring structure together with the nitrogen atom. The tertiary amine contained in formula (2) is preferably a cyclic amine.

[0050] R 5 The tertiary amine contained in is an acyclic amine (R 6 and R 7 does not form a ring structure with the nitrogen atom), R 6 and R 7 are preferably each independently a saturated aliphatic group having 1 to 4 carbon atoms. In this case, the tertiary amine (—NR 6 R 7 ) has a suitable bulkiness, resulting in a fluorine-containing ether compound with suitable steric hindrance and mobility. Therefore, the lubricating layer containing this fluorine-containing ether compound has a suitable bulkiness. 5This prevents intramolecular aggregation due to the interaction between the unshared electron pair of the nitrogen atom of the tertiary amine contained in the compound and the adjacent hydroxyl group, improving adhesion to the protective layer. As a result, it is possible to maintain a more appropriate coverage rate on the protective layer, resulting in a lubricating layer with better wear resistance.

[0051] R 6 and R 7 are each independently a saturated aliphatic group having 1 to 4 carbon atoms, examples of the saturated aliphatic group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Among these, a saturated aliphatic group having 1 to 2 carbon atoms is preferred. Specifically, R 6 and R 7 are preferably each independently a methyl group or an ethyl group, and R 6 and R 7 It is more preferable that R 5 When the tertiary amine contained in formula (2) is an acyclic amine, -NR 6 R 7 is preferably any one group selected from a dimethylamino group, a methylethylamino group, and a diethylamino group, and is more preferably a dimethylamino group or a diethylamino group because of ease of synthesis.

[0052] R 5 The tertiary amine contained in is an acyclic amine (R 6 and R 7 does not form a ring structure together with the nitrogen atom), the tertiary amine (—NR 6 R 7) include, for example, a dimethylamino group, a diethylamino group, a dipropylamino group, a diisopropylamino group, a di-n-butylamino group, a diisobutylamino group, a di-sec-butylamino group, a di-tert-butylamino group, an ethylmethylamino group, a n-propylmethylamino group, an isopropylmethylamino group, a n-butylmethylamino group, an isobutylmethylamino group, a sec-butylmethylamino group, a tert-butylmethylamino group, an ethyl-n-propylamino group, an ethylisopropylamino group, an ethyl-n-butylamino group, an ethylisobutylamino group, a sec-butylethylamino group, a tert-butylethylamino group, an isopropylpropylamino group, normal butylpropylamino group, (2-methylpropyl)(propyl)amino group, N-sec-butylpropylamino group, N-tert-butylpropylamino group, N-(1-methylethyl)-1-butylamino group, N-isopropyl-2-methyl-1-propylamino group, N-(1-methylethyl)-2-butylamino group, N-isopropyl-2-methyl-2-propylamino group, butylisobutylamino group, butyl-sec-butylamino group, butyl-tert-butylamino group, N-(2-methylpropyl)-2-butylamino group, N-(1,1-dimethylethyl)-2-methylpropylamino group, and N-(1,1-dimethylethyl)-2-butylamino group.

[0053] R 5 The tertiary amine contained in is a cyclic amine (R 6 and R 7 forms a ring structure together with the nitrogen atom), the tertiary amine (—NR 6 R 7 Specific examples of the alkyl group include an ethyleneimine group, an azacyclobutane group, a pyrrolidine group, a piperidine group, a morpholine group, a hexamethyleneimine group, a heptamethyleneimine group, and an octamethyleneimine group.

[0054] R 5 The tertiary amine contained in is a cyclic amine (R 6 and R 7When R forms a ring structure together with the nitrogen atom, the cyclic amine may have a substituent. Specific examples of the substituent include an alkyl group having 1 to 3 carbon atoms and a polar group. 5 When the cyclic amine contained in has a substituent containing a polar group, examples of the polar group include a hydroxyl group, an amino group, a carboxyl group, etc., and a hydroxyl group is preferable. The bonding position of the substituent in the cyclic amine having a substituent is not particularly limited, and the substituent may be bonded to any carbon atom constituting the cyclic amine. R 6 and R 7 When the nitrogen atom forms a ring structure together with the tertiary amine, the ring structure may contain a heteroatom other than the nitrogen atom of the tertiary amine. Examples of the heteroatom other than the nitrogen atom of the tertiary amine include an oxygen atom and / or a nitrogen atom.

[0055] R 5 When the tertiary amine contained in R is a cyclic amine, 6 and R 7 In this case, -NR in formula (2) preferably forms a 5- to 7-membered ring together with the nitrogen atom. 6 R 7 Since -NR has a moderate bulkiness, it becomes a fluorine-containing ether compound with a moderate steric hindrance and mobility. As a result, the lubricating layer containing this has good affinity with the protective layer and excellent wear resistance. Specifically, -NR in formula (2) 6 R 7 is preferably any one group selected from a pyrrolidine group, a piperidine group, a morpholine group, and a hexamethyleneimine group.

[0056] On the other hand, when the fluorine-containing ether compound represented by formula (1) has, for example, a primary amine or a secondary amine instead of the tertiary amine in formula (2), the primary amine or the secondary amine has a smaller steric hindrance than the tertiary amine, so that the unshared electron pair of the nitrogen atom is likely to interact with the adjacent hydroxyl group, and intramolecular aggregation is likely to occur. As a result, the lubricating layer containing this fluorine-containing ether compound has a low coverage and insufficient wear resistance.

[0057] Furthermore, when the fluorine-containing ether compound represented by formula (1) has an unsaturated heterocycle containing a nitrogen atom instead of the tertiary amine in formula (2), sufficient heat resistance cannot be obtained. This is because the unsaturated heterocycle containing a nitrogen atom undergoes thermal decomposition under heating conditions. Furthermore, the unsaturated heterocycle containing a nitrogen atom has lower mobility than the tertiary amine. Therefore, in a lubricating layer containing this fluorine-containing ether compound, the unshared electron pair in the lubricating layer is less likely to approach the protective layer, making it difficult to obtain adhesion to the protective layer. As a result, the wear resistance is insufficient.

[0058] (R 3 PFPE chain represented by In the fluorine-containing ether compound represented by formula (1), R 3 is a perfluoropolyether chain (hereinafter, sometimes abbreviated as "PFPE chain"). When a lubricant containing the fluorine-containing ether compound of this embodiment is applied to a protective layer to form a lubricating layer, the PFPE chain coats the surface of the protective layer and imparts lubricity to the lubricating layer, thereby reducing the frictional force between the magnetic head and the protective layer.

[0059] The PFPE chain is appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, etc. Examples of the PFPE chain include perfluoromethylene oxide polymers, perfluoroethylene oxide polymers, perfluoro-n-propylene oxide polymers, perfluoroisopropylene oxide polymers, and copolymers of the monomers that constitute these polymers.

[0060] The PFPE chain may be, for example, a structure represented by the following formula (Rf) derived from a polymer or copolymer of perfluoroalkylene oxide. -(CF2) w1 O(CF2O) w2 (CF2CF2O) w3 (CF2CF2CF2O) w4 (CF2CF2CF2CF2O) w5 (CF2) w6- (Rf) (In formula (Rf), w2, w3, w4, and w5 represent an average degree of polymerization and each independently represent 0 to 30; provided that w2, w3, w4, and w5 cannot all be 0 at the same time; w1 and w6 represent an average value indicating the number of -CF2- and each independently represent 1 to 3; there are no particular limitations on the arrangement order of repeating units in formula (Rf).) In formula (Rf), w2, w3, w4, and w5 represent average degrees of polymerization, each independently representing 0 to 30, preferably 0 to 20, and more preferably 0 to 15. In formula (Rf), w1 and w6 are average values ​​indicating the number of -CF2- groups, and each independently represents 1 to 3. w1 and w6 are determined depending on the structure of the repeating units located at the ends of the chain structure in the polymer represented by formula (Rf), etc. In formula (Rf), (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) are repeating units. There are no particular restrictions on the arrangement order of the repeating units in formula (Rf). There are also no particular restrictions on the number of types of repeating units in formula (Rf).

[0061] R in Equation (1) 3 is preferably a PFPE chain represented by the following formula (Rf-1), for example. -(CF2) w7 O-(CF2CF2O) w8 -(CF2CF2CF2O) w9 -(CF2) w10 - (Rf-1) (In formula (Rf-1), w8 and w9 represent the average degree of polymerization, each independently representing 0.1 to 30; w7 and w10 represent the average value representing the number of -CF2-, each independently representing 1 to 2.) The sequence of the repeating units (CFCFO) and (CFCFCFO) in formula (Rf-1) is not particularly limited. Formula (Rf-1) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of the monomer units (CFCFO) and (CFCFCFO). In formula (Rf-1), w8 and w9, which represent the average degree of polymerization, each independently represent 0.1 to 30, preferably 0.1 to 20, and more preferably 1 to 15. In formula (Rf-1), w7 and w10 represent the average number of -CF- groups and each independently represent 1 to 2. w7 and w10 are determined depending on the structure of the repeating units located at the ends of the chain structure in the polymer represented by formula (Rf-1).

[0062] R in Equation (1) 3 It is also preferable that R is represented by any one of the following formulas (5) to (7). 3 When R is any one of the formulas (5) to (7), the synthesis of the fluorine-containing ether compound is easy. 3 is formula (5) or (7), it is more preferable because raw materials are easily available. Also, R 3 When R is any one of the formulas (5) to (7), the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) to the number of carbon atoms in the perfluoropolyether chain is appropriate. This results in a fluorine-containing ether compound with appropriate hardness. Therefore, the fluorine-containing ether compound applied to the protective layer is less likely to aggregate on the protective layer, and a thinner lubricating layer can be formed with a sufficient coverage. In addition, R 3 When is any one of the formulas (5) to (7), the resulting fluorine-containing ether compound provides a lubricating layer with good wear resistance.

[0063] -CF2O-(CF2CF2O) h -(CF2O) i -CF2- (5) (In formula (5), h and i represent the average degree of polymerization and each represents 0 to 30; however, h and i cannot be 0 at the same time.) In formula (5), there is no particular limitation on the arrangement order of the repeating units (CF2-CF2-O) and (CF2-O). In formula (5), the number h of (CF2-CF2-O) and the number i of (CF2-O) may be the same or different. However, h and i cannot be 0 at the same time. Formula (5) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of the monomer units (CF2-CF2-O) and (CF2-O).

[0064] In formula (5), h, which indicates the average degree of polymerization, is 0 to 30, preferably 1 to 20, and more preferably 3 to 10, so that the fluorinated ether compound easily wets and spreads on the protective layer, and a lubricating layer having a uniform thickness is easily obtained. For example, h is also preferably 4 to 8 or 5 to 7. In formula (5), i, which indicates the average degree of polymerization, is 0 to 30, preferably 1 to 20, and more preferably 3 to 10, so that the fluorinated ether compound easily wets and spreads on the protective layer, and a lubricating layer having a uniform thickness is easily obtained. For example, i is also preferably 4 to 8 or 5 to 7.

[0065] -CF(CF3)-(OCF(CF3)CF2) j -OCF(CF3)- (6) (In formula (6), j represents the average degree of polymerization and is 0.1 to 30.) In formula (6), j, which indicates the average degree of polymerization, is 0.1 to 30, preferably 1 to 30, more preferably 2 to 20, and further preferably 3 to 10, since the fluorine-containing ether compound easily wets and spreads on the protective layer and easily forms a lubricating layer with a uniform thickness. For example, j is also preferably 4 to 8 or 5 to 7.

[0066] -CF2CF2O-(CF2CF2CF2O) k -CF2CF2- (7) (In formula (7), k represents the average degree of polymerization and is 0.1 to 30.) In formula (7), k, which indicates the average degree of polymerization, is 0.1 to 30, preferably 1 to 30, more preferably 2 to 20, and further preferably 3 to 10, since this fluorine-containing ether compound easily wets and spreads on the protective layer and easily forms a lubricating layer having a uniform thickness. For example, k is also preferably 4 to 8 or 5 to 7.

[0067] When h, i, j, and k, which represent the average degree of polymerization in the formulas (5) to (7), are 30 or less, the viscosity of the fluorinated ether compound does not become too high, and the lubricant containing it becomes easy to apply, which is preferable.

[0068] Here, the reason why the lubricating layer containing the fluorine-containing ether compound of this embodiment has excellent heat resistance and wear resistance will be described. In the fluorine-containing ether compound represented by formula (1), R 5 The tertiary amine contained in R 1 Specifically, the thermal decomposition of the alkenyl or alkynyl group in the fluorine-containing ether compound contained in the lubricating layer is suppressed. 5 The tertiary amine contained in the compound (1) scavenges radicals generated from oxygen in the atmosphere and oxygen present in the lubricating layer and / or on the protective layer under heat treatment conditions. As a result, the oxidative decomposition reaction of the alkenyl or alkynyl group contained in the fluorine-containing ether compound due to the radicals is suppressed. Therefore, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) has good heat resistance, and 1 The effect of improving the wear resistance due to the alkenyl or alkynyl group contained in the copolymer is maintained for a long period of time.

[0069] Examples of cases in which the lubricating layer is subjected to heat treatment include cases in which a substrate on which a lubricating layer has been formed is subjected to heat treatment at a temperature of, for example, 100°C to 180°C in order to improve adhesion between the lubricating layer and the protective layer, and cases in which ultraviolet (UV) rays are irradiated onto the substrate on which a lubricating layer has been formed before or after the heat treatment.

[0070] In general, the alkenyl or alkynyl group in a fluorine-containing ether compound is susceptible to oxidation. For this reason, for example, when a lubricating layer containing a fluorine-containing ether compound that does not contain a tertiary amine and has an alkenyl or alkynyl group is subjected to heat treatment conditions, the alkenyl or alkynyl group is thermally decomposed to produce an oxidative decomposition product.

[0071] The oxidative decomposition products produced by thermal decomposition of the alkenyl or alkynyl groups in the fluorinated ether compound are presumed to be compounds containing aldehydes or ketones. These oxidative decomposition products are presumed to be produced by radicals generated under heat treatment conditions from oxygen in the atmosphere and oxygen present in the lubricating layer and / or on the protective layer, which oxidize the α- and / or β-positions of the alkenyl or alkynyl groups in the lubricating layer. The oxidative decomposition products produced by thermal decomposition are unstable compounds, and are therefore thought to accelerate the oxidative decomposition of the alkenyl or alkynyl groups in the lubricating layer and accelerate the deterioration of the lubricating layer. As a result, it is presumed that the wear resistance improving effect of the alkenyl or alkynyl groups in the lubricating layer, which does not contain a tertiary amine and contains a fluorine-containing ether compound having an alkenyl or alkynyl group, will decrease in a short period of time.

[0072] Specifically, the fluorine-containing ether compound of the present embodiment is preferably a compound represented by the following formulas (A) to (I): In the formulas (A) to (I), ma to mh, na to nd, and pi are values ​​indicating the average degree of polymerization, and are not necessarily integers.

[0073] The compounds represented by the following formulas (A) to (H) are all the same as R in the above formula (1). 3 is a PFPE chain represented by the above formula (5), and R 4 is the above formula (4). R 2 is the above equation (3). The compound represented by the following formula (A) is a compound represented by the formula (1) 1 is an allyl group, and R 2In (X), z is 0, b is 1, c is 2, e is 0 in (Y), g in formula (2) is 3, -NR 6 R 7 is a morpholine group.

[0074] The compound represented by the following formula (B) is a compound represented by the formula (1) 1 is an allyl group, and R 2 a in (X) is 2, z is 1, b in (X) is 1, c is 2, e in (Y) is 0, g in formula (2) is 2, -NR 6 R 7 is a piperidine group. The compound represented by the following formula (C) is a compound represented by the formula (1) 1 is a propargyl group, and R 2 a in (X) is 2, z is 1, b in (X) is 1, c is 2, e in (Y) is 0, g in formula (2) is 2, -NR 6 R 7 is a pyrrolidine group.

[0075] [ka] (In formula (A), ma and na represent the average degree of polymerization, ma representing 1 to 30, and na representing 0 to 30.) (In formula (B), mb and nb represent the average degree of polymerization, mb represents 1 to 30, and nb represents 0 to 30.) (In formula (C), mc and nc represent the average degree of polymerization, mc represents 1 to 30, and nc represents 0 to 30.) The ma, mb, and mc may be, for example, 1 to 20, 2 to 15, 3 to 10, 4 to 8, or 5 to 7. The na, nb, and nc may be, for example, 0 to 25, 1 to 20, 2 to 15, 3 to 10, 4 to 8, or 5 to 7.

[0076] The compound represented by the following formula (D) is a compound represented by the formula (1) 1 is an allyl group, and R 2a in (X) is 2, z is 1, b in (X) is 1, c is 2, e in (Y) is 0, g in formula (2) is 3, -NR 6 R 7 is a dimethylamino group. The compound represented by the following formula (E) is a compound represented by the formula (1) 1 is an allyl group, and R 2 In (X), z is 0, b is 1, c is 2, e is 0 in (Y), g is 2 in formula (2), -NR 6 R 7 is a morpholine group. The compound represented by the following formula (F) is a compound represented by the formula (1) 1 is a butenyl group, and R 2 In (X), z is 0, b is 1, c is 1, d is 2, e is 1 in (Y), g in formula (2) is 2, -NR 6 R 7 is a morpholine group.

[0077] [ka] (In formula (D), md and nd represent the average degree of polymerization, md represents 1 to 30, and nd represents 0 to 30.) (In formula (E), me represents the average degree of polymerization, and me represents 0.1 to 30.) (In formula (F), mf represents the average degree of polymerization, and mf represents 0.1 to 30.) The md may be, for example, 1 to 20, 2 to 15, 3 to 10, 4 to 8, or 5 to 7. The nd may be, for example, 0 to 25, 1 to 20, 2 to 15, 3 to 10, 4 to 8, or 5 to 7. The me and mf may be, for example, 0.1 to 25, 0.3 to 20, 0.5 to 15, 1 to 10, 2 to 8, or 3 to 6.

[0078] The compound represented by the following formula (G) is a compound represented by the formula (1) 1 is a butenyl group, and R 2In (X), z is 0, b is 1, c is 1, d is 2, e is 1 in (Y), g in formula (2) is 2, -NR 6 R 7 is a diethylamino group. The compound represented by the following formula (H) is a compound represented by the formula (1) 1 is a pentenyl group, and R 2 In (X), z is 0, b is 1, c is 2, e is 0 in (Y), g is 2 in formula (2), -NR 6 R 7 is a hexamethyleneimine group. The compound represented by the following formula (I) is a compound represented by the formula (1) 3 is a PFPE chain represented by formula (7), and R 4 is the above formula (4), and R 1 is a propargyl group, and R 2 a in (X) is 2, z is 1, b in (X) is 1, c is 2, e in (Y) is 0, g in formula (2) is 3, -NR 6 R 7 is a pyrrolidine group.

[0079] [ka] (In formula (G), mg represents the average degree of polymerization, and mg represents 0.1 to 30.) (In formula (H), mh represents the average degree of polymerization, and mh represents 0.1 to 30.) (In formula (I), pi represents the average degree of polymerization, and pi represents 0.1 to 30.) The mg, mh, and pi may be, for example, 0.1 to 25, 0.3 to 20, 0.5 to 15, 1 to 10, 2 to 8, or 3 to 6.

[0080] When the compound represented by formula (1) is any of the compounds represented by formulas (A) to (I), the raw materials are easily available. Furthermore, all of the compounds represented by formulas (A) to (I) have excellent heat resistance. Furthermore, the compounds represented by formulas (A) to (I) can form a lubricating layer that has even better wear resistance and heat resistance, even if the thickness is thin. It is more preferable that the compound represented by formula (1) is any of the compounds represented by formulas (A), (B), (E), (F), and (I), because it can form a lubricating layer that is particularly excellent in heat resistance.

[0081] The fluorine-containing ether compound of this embodiment preferably has a number-average molecular weight (Mn) 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 1,000 to 3,000. When the number-average molecular weight is 500 or more, the lubricant containing the fluorine-containing ether compound of this embodiment is less likely to evaporate, preventing the lubricant from evaporating and transferring to a magnetic head. Furthermore, when the number-average molecular weight is 10,000 or less, the viscosity of the fluorine-containing ether compound is appropriate, and a thin lubricating layer can be easily formed by applying a lubricant containing the compound. A number-average molecular weight of 3,000 or less is more preferred because it results in a viscosity that is easy to handle when applied to a lubricant.

[0082] The number average molecular weight (Mn) of fluorine-containing ether compounds was measured using AVANCEIII400 manufactured by Bruker Biospin. 1 H-NMR and 19 This is a value measured by F-NMR. In NMR (nuclear magnetic resonance) measurements, samples were diluted in a single or mixed solvent such as hexafluorobenzene, d-acetone, or d-tetrahydrofuran and used for the measurements. 19 The reference for F-NMR chemical shifts is the hexafluorobenzene peak at -164.7 ppm. 1 The reference for H-NMR chemical shifts was the acetone peak at 2.2 ppm.

[0083] "Manufacturing method" The method for producing the fluorinated ether compound of the present embodiment is not particularly limited, and the compound can be produced by a conventionally known production method. The fluorinated ether compound of the present embodiment can be produced, for example, by the production method shown below.

[0084] First, R in Equation (1) 3 A fluorine-based compound is prepared in which a hydroxymethyl group (-CH2OH) is placed at each end of the perfluoropolyether chain corresponding to Next, the hydroxyl group of the hydroxymethyl group located at one end of the fluorine-based compound is converted to R 1 -OR 2 Then, the hydroxyl group of the hydroxymethyl group located at the other end is replaced with a group consisting of -R 4 -R 5 (second reaction)

[0085] The first and second reactions can be carried out by a conventionally known method, and R 1 , R 2 , R 4 , R 5 The reaction time can be determined appropriately depending on the type of the catalyst, etc. Either the first reaction or the second reaction may be carried out first. By the above method, the compound represented by formula (1) can be obtained.

[0086] In this embodiment, for example, R 1 -OR 2 In the first reaction for introducing a group consisting of -, the hydroxyl group of the hydroxymethyl group at one end of the fluorine-based compound and R 1 -OR 2 It is preferable to react the compound with the corresponding epoxy compound. In the second reaction, the fluorine-based compound is 4 -R 5 To introduce a group consisting of: 4 -R 5It is preferable to react the compound with an epoxy compound corresponding to the following formula:

[0087] The epoxy compound used in producing the fluorinated ether compound of the present embodiment may be, for example, R 1 -OR 2 - or an end group represented by -R 4 -R 5 The epoxy compound can be synthesized by reacting an alcohol having a structure corresponding to the terminal group represented by the formula (1) with a compound having an epoxy group selected from epichlorohydrin, epibromohydrin, 2-bromoethyloxirane, and allyl glycidyl ether. Such an epoxy compound may be synthesized by oxidizing an unsaturated bond, or a commercially available product may be purchased and used.

[0088] By forming a lubricating layer on a protective layer using a lubricant containing the fluorinated ether compound of this embodiment, the following effects can be obtained. In the fluorine-containing ether compound represented by formula (1), R 1 The alkenyl or alkynyl group in the compound exhibits good interaction with the protective layer, and as a result, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) can maintain an appropriate coverage rate with the protective layer and has excellent wear resistance.

[0089] Also, R 5 The tertiary amine contained in R 1 The thermal decomposition of the alkenyl or alkynyl group in R is suppressed. As a result, the fluorine-containing ether compound represented by formula (1) and the lubricating layer using the same have good heat resistance. More specifically, 5 The tertiary amine contained in the compound (I) scavenges radicals generated under heat treatment conditions, such as heat treatment carried out at a temperature in the range of 100°C to 180°C. 1 The oxidation reaction of the alkenyl or alkynyl group in R 1 The effect of improving the wear resistance due to the alkenyl or alkynyl group in the alkyl group is maintained.

[0090] Furthermore, R 5 The unshared electron pair of the nitrogen atom forming the tertiary amine contained in the compound (1) exhibits good interaction with the protective layer, resulting in a lubricating layer with good adhesion to the protective layer, which allows the lubricating layer to maintain an appropriate coverage rate with respect to the protective layer and provides excellent wear resistance. Also, R 5 The tertiary amine contained in has moderate steric hindrance and mobility. Therefore, it is possible to prevent aggregation due to interaction with the hydroxyl group adjacent to the tertiary amine without impairing the interaction with the protective layer through the unshared electron pair of the nitrogen atom forming the tertiary amine. As a result, a lubricating layer with an appropriate coverage rate relative to the protective layer and excellent wear resistance is obtained.

[0091] R in the lubricating layer 3 The surface of the protective layer is covered with the PFPE chains represented by R 3 R linked to the first end of the PFPE chain represented by 2 and the bond between the hydroxyl group and the protective layer, and R 4 The lubricating layer is adhered to the protective layer by the bond between the hydroxyl group of the compound and the protective layer. That is, the fluorine-containing ether compound represented by formula (1) has two or more hydroxyl groups in the molecule at appropriate positions, so that the interaction between the hydroxyl group and the protective layer is effectively obtained, and the surface of the protective layer is covered with a high coverage. Therefore, the lubricating layer containing the fluorine-containing ether compound of this embodiment is firmly bonded to the protective layer and has excellent wear resistance.

[0092] [Lubricants for magnetic recording media] The lubricant for a magnetic recording medium of this embodiment contains a fluorine-containing ether compound represented by formula (1). The lubricant of the present embodiment can be used by mixing, as needed, known materials used as lubricant materials, as long as the properties resulting from the inclusion of the fluorinated ether compound represented by formula (1) are not impaired.

[0093] Specific examples of known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco), etc. The known material to be mixed with the lubricant of the present embodiment preferably has a number average molecular weight of 1,000 to 10,000.

[0094] When the lubricant of this embodiment contains a material other than the fluorinated ether compound represented by formula (1), the content of the fluorinated ether compound represented by formula (1) in the lubricant of this embodiment 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) may be 80% by mass or more, or may be 90% by mass or more. The upper limit of the content can be selected arbitrarily and may be, for example, 99% by mass, 97% by mass, or 95% by mass.

[0095] The lubricant of this embodiment contains a fluorine-containing ether compound represented by formula (1), and therefore, even when the thickness is thin, it can cover the surface of the protective layer with a high coverage rate, and can form a lubricating layer that has excellent adhesion to the protective layer and excellent wear resistance and heat resistance.

[0096] [Magnetic recording media] The magnetic recording medium of this embodiment has at least a magnetic layer, a protective layer, and a lubricating layer provided in this order on a substrate. In the magnetic recording medium of this embodiment, one or more underlayers may be provided between the substrate and the magnetic layer, if necessary. An adhesive layer and / or a soft magnetic layer may also be provided between the underlayer and the substrate.

[0097] FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of the magnetic recording medium of the present invention. The magnetic recording medium 10 of this embodiment has a structure in which an adhesive layer 12, a soft magnetic layer 13, a first underlayer 14, a second underlayer 15, a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are sequentially provided on a substrate 11.

[0098] "substrate" The substrate 11 may be, for example, a non-magnetic substrate in which a film made of NiP or a NiP alloy is formed on a base made of a metal or alloy material such as Al or an Al alloy. The substrate 11 may be a non-magnetic substrate made of a non-metallic material such as glass, ceramics, silicon, silicon carbide, carbon, or resin, or may be a non-magnetic substrate having a NiP or NiP alloy film formed on a base made of any of these non-metallic materials.

[0099] "Adhesion layer" The adhesive layer 12 prevents the progress of corrosion of the substrate 11, which occurs when the substrate 11 and the soft magnetic layer 13 provided on the adhesive layer 12 are disposed in contact with each other. The material of the adhesive layer 12 can be appropriately selected from, for example, Cr, a Cr alloy, Ti, a Ti alloy, CrTi, NiAl, an AlRu alloy, etc. The adhesive layer 12 can be formed by, for example, a sputtering method.

[0100] "Soft magnetic layer" The soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer made of a Ru film, and a second soft magnetic film are laminated in this order. That is, the soft magnetic layer 13 preferably has a structure in which the intermediate layer made of a Ru film is sandwiched between two soft magnetic films, and the soft magnetic films above and below the intermediate layer are antiferro-coupling (AFC).

[0101] Examples of materials for the first and second soft magnetic films include a CoZrTa alloy and a CoFe alloy. It is preferable to add Zr, Ta, or Nb to the CoFe alloy used in the first and second soft magnetic films, which promotes the amorphization of the first and second soft magnetic films, improves the orientation of the first underlayer (seed layer), and reduces the flying height of the magnetic head. The soft magnetic layer 13 can be formed by, for example, a sputtering method.

[0102] "First base layer" The first underlayer 14 is a layer that controls the orientation and crystal size of the second underlayer 15 and magnetic layer 16 that are provided thereon. The first underlayer 14 may be, for example, a Cr layer, a Ta layer, a Ru layer, a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, or a CrTi alloy layer. The first underlayer 14 can be formed by, for example, a sputtering method.

[0103] "Second base layer" The second underlayer 15 is a layer that controls the orientation of the magnetic layer 16. The second underlayer 15 is preferably a layer made of Ru or a Ru alloy. The second underlayer 15 may be a single layer or may be composed of multiple layers. When the second underlayer 15 is composed of multiple layers, all of the layers may be composed of the same material, or at least one layer may be composed of a different material. The second underlayer 15 can be formed by, for example, a sputtering method.

[0104] "Magnetic layer" The magnetic layer 16 is a magnetic film with an easy axis of magnetization oriented perpendicular or parallel to the substrate surface. The magnetic layer 16 contains Co and Pt, and may also contain oxides, Cr, B, Cu, Ta, Zr, or the like to further improve the SNR characteristics. Examples of oxides contained in the magnetic layer 16 include SiO2, SiO, Cr2O3, CoO, Ta2O3, and TiO2.

[0105] The magnetic layer 16 may be composed of a single layer, or may be composed of multiple magnetic layers made of materials with different compositions. For example, when the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer stacked in this order from the bottom, the first magnetic layer preferably has a granular structure made of a material containing Co, Cr, and Pt and further containing an oxide. The oxide contained in the first magnetic layer is preferably an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, or the like. Among these, TiO2, Cr2O3, SiO2, and the like are particularly suitable. Furthermore, the first magnetic layer is preferably made of a composite oxide containing two or more types of oxides. Among these, Cr2O3-SiO2, Cr2O3-TiO2, SiO2-TiO2, and the like are particularly suitable.

[0106] 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. The second magnetic layer may be made of the same material as the first magnetic layer. The second magnetic layer preferably has a granular structure.

[0107] The third magnetic layer preferably has a non-granular structure made of a material containing Co, Cr, and Pt and not containing oxides, and may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn in addition to Co, Cr, and Pt.

[0108] When magnetic layer 16 is formed of multiple magnetic layers, it is preferable to provide a non-magnetic layer between adjacent magnetic layers. When magnetic layer 16 is formed of three layers, namely, 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.

[0109] The non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16 can suitably be made of, for example, Ru, a Ru alloy, a CoCr alloy, or a 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, and B).

[0110] The non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16 preferably uses an alloy material containing an oxide, metal nitride, or metal carbide. Specifically, oxides that can be used include, for example, SiO2, Al2O3, Ta2O5, Cr2O3, MgO, Y2O3, and TiO2. Metal nitrides that can be used include, for example, AlN, Si3N4, TaN, and CrN. Metal carbides that can be used include, for example, TaC, BC, and SiC. The non-magnetic layer can be formed by, for example, a sputtering method.

[0111] To achieve higher recording density, the magnetic layer 16 is preferably a magnetic layer for perpendicular magnetic recording, in which the axis of easy magnetization is oriented perpendicular to the substrate surface, but may also be a magnetic layer for longitudinal magnetic recording. The magnetic layer 16 may be formed by any known method such as vapor deposition, ion beam sputtering, magnetron sputtering, etc. The magnetic layer 16 is usually formed by sputtering.

[0112] "Protective layer" The protective layer 17 protects the magnetic layer 16. The protective layer 17 may be made of a single layer or multiple layers. Examples of materials for the protective layer 17 include carbon, carbon containing nitrogen, and silicon carbide. A carbon-based protective layer, particularly an amorphous carbon protective layer, can be preferably used as the protective layer 17. When the protective layer 17 is a carbon-based protective layer, the interaction with the hydroxyl group contained in the fluorine-containing ether compound in the lubricating layer 18 is further enhanced, which is preferable.

[0113] The adhesion between the carbon-based protective layer and the lubricating layer 18 can be controlled by using hydrogenated carbon and / or nitrogenated carbon for the carbon-based protective layer and adjusting the hydrogen and / or nitrogen content in the carbon-based protective layer. The hydrogen content in the carbon-based protective layer is preferably 3 to 20 atomic % when measured by hydrogen forward scattering (HFS). The nitrogen content in the carbon-based protective layer is preferably 4 to 15 atomic % when measured by X-ray photoelectron spectroscopy (XPS).

[0114] The hydrogen and / or nitrogen contained in the carbon-based protective layer does not need to be uniformly contained throughout the carbon-based protective layer. The carbon-based protective layer is preferably a compositionally graded layer, for example, in which nitrogen is contained on the lubricating layer 18 side of protective layer 17 and hydrogen is contained on the magnetic layer 16 side of protective layer 17. In this case, the adhesion between the magnetic layer 16 and lubricating layer 18 and the carbon-based protective layer is further improved.

[0115] 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, sufficient performance as the protective layer 17 can be obtained. If the thickness of the protective layer 17 is 7 nm or less, it is preferable from the viewpoint of making the protective layer 17 thinner.

[0116] The protective layer 17 can be formed by sputtering using a target material containing carbon, CVD (chemical vapor deposition) using a hydrocarbon raw material such as ethylene or toluene, or IBD (ion beam deposition). When a carbon-based protective layer is formed as protective layer 17, it can be deposited by, for example, DC magnetron sputtering. In particular, when a carbon-based protective layer is formed as protective layer 17, it is preferable to deposit an amorphous carbon protective layer by plasma CVD. The amorphous carbon protective layer deposited by plasma CVD has a uniform surface with little roughness.

[0117] "Lubricant layer" The lubricating layer 18 prevents contamination of the magnetic recording medium 10. The lubricating layer 18 also reduces the frictional force of the magnetic head of the magnetic recording / reproducing device that slides on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10. 1, the lubricating layer 18 is formed on and in contact with the protective layer 17. The lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.

[0118] When the protective layer 17 disposed below the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 bonds with the protective layer 17 with particularly high bonding strength. As a result, even if the thickness of the lubricating layer 18 is thin, it becomes easier to obtain a magnetic recording medium 10 in which the surface of the protective layer 17 is covered with a high coverage, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented.

[0119] The average thickness of the lubricating layer 18 is preferably 0.5 nm (5 Å) to 2.0 nm (20 Å), and more preferably 0.5 nm (5 Å) to 1.0 nm (10 Å). When the average thickness of the lubricating layer 18 is 0.5 nm or more, the lubricating layer 18 is formed with a uniform thickness without forming an island or mesh-like structure. This allows the lubricating layer 18 to cover the surface of the protective layer 17 with a high coverage. Furthermore, by setting the average thickness of the lubricating layer 18 to 2.0 nm or less, the lubricating layer 18 can be made sufficiently thin, and the flying height of the magnetic head can be sufficiently reduced.

[0120] If the surface of the protective layer 17 is not covered with the lubricating layer 18 at a sufficiently high coverage rate, environmental substances adsorbed to the surface of the magnetic recording medium 10 will pass through the gaps in the lubricating layer 18 and penetrate underneath the lubricating layer 18. The environmental substances that penetrate underneath the lubricating layer 18 will adsorb and bond to the protective layer 17, generating contaminants. The generated contaminants (aggregated components) will adhere (transfer) to the magnetic head as smear during magnetic recording and playback, damaging the magnetic head or degrading the magnetic recording and playback characteristics of the magnetic recording and playback device.

[0121] Environmental substances that generate contaminants include, for example, siloxane compounds (cyclic siloxanes, linear siloxanes), ionic impurities, hydrocarbons with relatively high molecular weights such as octacosane, 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.

[0122] "Method for forming lubricating layer" A method for forming the lubricating layer 18 includes, for example, preparing a magnetic recording medium in the middle of manufacturing in which the layers up to the protective layer 17 are formed on the substrate 11, applying a solution for forming the lubricating layer onto the protective layer 17, and drying the solution.

[0123] The lubricant layer forming solution can be obtained by dispersing and dissolving the lubricant for a magnetic recording medium according to the above embodiment in a solvent as needed, and adjusting the viscosity and concentration to suit the coating method. Examples of the solvent used in the lubricating layer-forming solution include fluorine-based solvents such as Vertrel (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.).

[0124] The method for applying the lubricating layer-forming solution is not particularly limited, but examples thereof include spin coating, spraying, paper coating, and dipping. When using the dipping method, for example, the following method can be used. First, the substrate 11 on which each layer up to the protective layer 17 has been formed is immersed in a lubricant layer-forming solution placed in an immersion tank of a dip coating device. Next, the substrate 11 is lifted from the immersion tank at a predetermined speed. In this way, the lubricant layer-forming solution is applied to the surface of the substrate 11 above the protective layer 17. By using the dipping method, the lubricating layer forming solution can be applied uniformly to the surface of the protective layer 17, and the lubricating layer 18 can be formed on the protective layer 17 with a uniform thickness.

[0125] In this embodiment, it is preferable to perform a heat treatment on the substrate 11 on which the lubricating layer 18 is formed. By performing the heat treatment, the adhesion between the lubricating layer 18 and the protective layer 17 is improved, and the adhesive force between the lubricating layer 18 and the protective layer 17 is also improved. The heat treatment temperature is preferably 100 to 180° C. If the heat treatment temperature is 100° C. or higher, the effect of improving the adhesion between the lubricating layer 18 and the protective layer 17 can be sufficiently obtained. Furthermore, by setting the heat treatment temperature to 180° C. or lower, thermal decomposition of the lubricating layer 18 can be prevented. The heat treatment time is preferably 10 to 120 minutes. In this embodiment, in order to further improve the adhesion of the lubricating layer 18 to the protective layer 17, the lubricating layer 18 on the substrate 11 may be irradiated with ultraviolet (UV) rays before or after the heat treatment.

[0126] The magnetic recording medium 10 of this embodiment includes at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18, which are sequentially formed on a substrate 11. In the magnetic recording medium 10 of this embodiment, a lubricating layer 18 containing the above-described fluorine-containing ether compound is formed on and in contact with the protective layer 17. Despite its thin thickness, this lubricating layer 18 covers the surface of the protective layer 17 with a high coverage. Therefore, the magnetic recording medium 10 of this embodiment prevents environmental substances that generate contaminants, such as ionic impurities, from penetrating through gaps in the lubricating layer 18. Therefore, the magnetic recording medium 10 of this embodiment has minimal contaminants present on its surface. Furthermore, the lubricating layer 18 of the magnetic recording medium 10 of this embodiment is less likely to produce foreign matter (smear), thereby suppressing pickup. Furthermore, the lubricating layer 18 of the magnetic recording medium 10 of this embodiment has excellent heat resistance and wear resistance. Therefore, the magnetic recording medium 10 of this embodiment has excellent reliability and durability. [Example]

[0127] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0128] ( Reference example 1) The compound represented by the above formula (A) was produced by the method shown below. Under a nitrogen gas atmosphere, HOCH2CF2O (CF2CF2O) was added to a 100 mL recovery flask. m (CF2O) n 40 g of a compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m is 4.5 and n is 4.5), 6.5 g of a compound (molecular weight 272.3, 24 mmol) represented by the following formula (8), and 38 mL of t-butanol (t-BuOH) were charged and stirred at room temperature until homogeneous. 1.4 g of potassium tert-butoxide (t-BuOK) (molecular weight 112.21, 12 mmol) was added to this homogeneous solution, and the mixture was stirred at 70°C for 16 hours to react.

[0129] The compound represented by formula (8) was synthesized by oxidizing one of the double bond groups of a compound in which the hydroxyl groups of glycerol α,α'-diallyl ether were protected using dihydropyran.

[0130] The resulting reaction product was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated using anhydrous sodium sulfate. After filtering off the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography. By performing the above steps, 20.2 g (molecular weight 1272.3, 15.9 mmol) of the compound represented by the following formula (9) was obtained as an intermediate.

[0131] [ka] (In formula (8), THP represents a tetrahydropyranyl group.) (In formula (9), m, which represents the average degree of polymerization, is 4.5, and n, which represents the average degree of polymerization, is 4.5. THP represents a tetrahydropyranyl group.)

[0132] Under a nitrogen gas atmosphere, 6.4 g (molecular weight 1272.3, 5.0 mmol) of the intermediate compound represented by formula (9), 1.1 g (molecular weight 201.3, 5.5 mmol) of the compound represented by formula (10) below, and 2.4 mL of t-butanol were charged into a 100 mL recovery flask and stirred at room temperature until homogeneous. To this homogeneous solution, 1.87 g (molecular weight 112.21, 25.2 mmol) of potassium tert-butoxide was added and the mixture was stirred at 70°C for 22.5 hours to react. The compound represented by formula (10) was synthesized by reacting the primary hydroxyl group of 4-(3-hydroxypropyl)morpholine with epibromohydrin.

[0133] [ka]

[0134] The reaction mixture was returned to room temperature, and 26 g of a 10% hydrogen chloride-methanol solution (hydrogen chloride-methanol reagent (5-10%), Tokyo Chemical Industry Co., Ltd.) was added and stirred at room temperature for 3.5 hours. The reaction mixture was gradually transferred to a separatory funnel containing 100 mL of brine and extracted twice with 200 mL of ethyl acetate. The organic layer was washed sequentially with 100 mL of brine, 100 mL of saturated sodium bicarbonate solution, and 100 mL of brine, and then dehydrated over anhydrous sodium sulfate. After filtering off the desiccant (anhydrous sodium sulfate), the filtrate was concentrated, and the residue was purified by silica gel column chromatography. Through these steps, 4.6 g (3.3 mmol) of compound (A) was obtained. (In formula (A), ma, which indicates the average degree of polymerization, is 4.5, and na, which indicates the average degree of polymerization, is 4.5.)

[0135] The obtained compound (A) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CD3COCD3); δ[ppm]1.6~1.7(2H), 2.4~2.5(6H), 3.4~4.2(30H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0136] ( Reference example 2) The experiment was carried out in the same manner as above except that 6.6 g of a compound represented by the following formula (11) was used instead of the compound represented by formula (8) and 1.0 g of a compound represented by the following formula (12) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.7 g of the compound represented by the above formula (B) (in formula (B), mb indicating the average degree of polymerization is 4.5, and nb indicating the average degree of polymerization is 4.5).

[0137] [ka] (In formula (11), MOM represents a methoxymethyl group.)

[0138] [ka]

[0139] The compound represented by formula (11) was synthesized by the following method. Epibromohydrin was reacted with the primary hydroxyl group of ethylene glycol monoallyl ether, and the resulting compound was reacted with sulfuric acid to obtain a dialcohol. The primary hydroxyl group of the resulting dialcohol was protected with a t-butyldimethylsilyl group using t-butyldimethylsilyl chloride, and then the secondary hydroxyl group was protected with a methoxymethyl (MOM) group using methoxymethyl chloride. The t-butyldimethylsilyl group of the resulting compound was removed, and the resulting primary hydroxyl group was reacted with epibromohydrin. The compound represented by formula (11) was obtained by the above steps.

[0140] The compound represented by formula (12) was synthesized by reacting the primary hydroxyl group of 1-piperidineethanol with epibromohydrin.

[0141] The obtained compound (B) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CD3COCD3); δ[ppm]1.5~1.6(6H), 2.5~2.8(6H), 3.4~4.2(30H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0142] ( Reference example 3) The experiment was carried out in the same manner as above except that 6.6 g of a compound represented by the following formula (13) was used instead of the compound represented by formula (8), and 0.9 g of a compound represented by the following formula (14) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.6 g of the compound represented by the above formula (C) (in formula (C), mc indicating the average degree of polymerization is 4.5, and nc indicating the average degree of polymerization is 4.5).

[0143] [ka] (In formula (13), MOM represents a methoxymethyl group.)

[0144] [ka]

[0145] The compound represented by formula (13) was synthesized in the same manner as for the compound represented by formula (11), except that 2-(2-propynyloxy)ethanol was used instead of ethylene glycol monoallyl ether. The compound represented by formula (14) was synthesized by reacting the primary hydroxyl group of 1-(2-hydroxyethyl)pyrrolidine with epibromohydrin.

[0146] The obtained compound (C) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CD3COCD3); δ[ppm]1.6~1.7(4H), 2.5~2.8(7H), 3.4~4.2(30H) 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0147] Example 4 The experiment was carried out in the same manner as above, except that 6.6 g of the compound represented by formula (11) was used instead of the compound represented by formula (8), and 0.9 g of the compound represented by formula (15) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.6 g of the compound represented by the above formula (D) (in formula (D), md indicating the average degree of polymerization is 4.5, and nd indicating the average degree of polymerization is 4.5).

[0148] [ka]

[0149] The compound represented by formula (15) was synthesized by reacting epibromohydrin with the primary hydroxyl group of 3-(dimethylamino)-1-propanol.

[0150] The obtained compound (D) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR (CD3COCD3); δ[ppm]1.7~1.8(2H), 2.3(6H), 2.5~2.6(2H)3.4~4.2(32H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0151] ( Reference example 5) Reference example 1 of HOCH2CF2O(CF2CF2O) m (CF2O) n Instead of the compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5), HOCH2CF2O(CF2CF2O) m′ (CF2O) n′ The compound (number average molecular weight: 1000, molecular weight distribution: 1.1) represented by CF2CH2OH (where m', which indicates the average degree of polymerization, is 7.1, and n', which indicates the average degree of polymerization, is 0) was used, and 1.0 g of the compound represented by the following formula (16) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.5 g of the compound represented by the above formula (E) (in formula (E), me, which indicates the average degree of polymerization, is 7.1).

[0152] [ka]

[0153] The compound represented by formula (16) was synthesized by reacting epibromohydrin with the primary hydroxyl group of 4-(2-hydroxyethyl)morpholine.

[0154] The obtained compound (E) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CD3COCD3);δ[ppm]2.4~2.5(6H), 3.4~4.2(30H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19F-NMR (acetone-D6): δ[ppm]=-78.6(2F), -81.3(2F), -90.0~-88.5(28F)

[0155] ( Reference example 6) Reference example 1 of HOCH2CF2O(CF2CF2O) m (CF2O) n Instead of the compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5), HOCH2CF2O(CF2CF2O) m′ (CF2O) n′ The following conditions were met: a compound (number average molecular weight: 1000, molecular weight distribution: 1.1) represented by CF2CH2OH (where m', which indicates the average degree of polymerization, is 7.1, and n', which indicates the average degree of polymerization, is 0) was used; 5.2 g of a compound represented by the following formula (17) was used instead of the compound represented by formula (8); and 1.0 g of a compound represented by the above formula (16) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.6 g of the compound represented by the above formula (F) (in formula (F), mf indicating the average degree of polymerization is 7.1).

[0156] [ka]

[0157] The compound represented by formula (17) was synthesized by reacting 3-buten-1-ol with epichlorohydrin, and then oxidizing one of the double bond groups of the compound obtained.

[0158] The obtained compound (F) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1H-NMR(CD3COCD3);δ[ppm]1.6~1.8(2H), 2.3~2.4(2H), 2.4~2.5(6H), 3.4~4.2(30H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19 F-NMR (acetone-D6): δ[ppm]=-78.6(2F), -81.3(2F), -90.0~-88.5(28F)

[0159] Example 7 Reference example 1 of HOCH2CF2O(CF2CF2O) m (CF2O) n Instead of the compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5), HOCH2CF2O(CF2CF2O) m′ (CF2O) n′ The following conditions were met: a compound (number average molecular weight: 1000, molecular weight distribution: 1.1) represented by CF2CH2OH (where m', which indicates the average degree of polymerization, is 7.1, and n', which indicates the average degree of polymerization, is 0) was used; 5.2 g of the compound represented by the above formula (17) was used instead of the compound represented by formula (8); and 1.8 g of the compound represented by the following formula (18) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.8 g of the compound represented by the above formula (G) (in formula (G), mg representing the average degree of polymerization is 7.1).

[0160] [ka] (In formula (18), THP represents a tetrahydropyranyl group.)

[0161] The compound represented by formula (18) was synthesized by the following method. Allyl glycidyl ether was reacted with the primary hydroxyl group of 2-diethylaminoethanol. The primary hydroxyl group of the obtained compound was protected with a tetrahydropyranyl (THP) group, and the terminal double bond of the obtained compound was oxidized. Through the above steps, the compound represented by formula (18) was obtained.

[0162] The obtained compound (G) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CD3COCD3);δ[ppm]1.0(6H), 1.6~1.8(2H), 2.3~2.4(2H), 2.5~2.6(6H), 3.4~4.2(32H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19 F-NMR (acetone-D6): δ[ppm]=-78.6(2F), -81.3(2F), -90.0~-88.5(28F)

[0163] ( Reference example 8) Reference example 1 of HOCH2CF2O(CF2CF2O) m (CF2O) n Instead of the compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5), HOCH2CF2O(CF2CF2O) m′ (CF2O) n′ The following conditions were met: a compound (number average molecular weight: 1000, molecular weight distribution: 1.1) represented by CF2CH2OH (where m', which indicates the average degree of polymerization, is 7.1, and n', which indicates the average degree of polymerization, is 0) was used; 6.2 g of a compound represented by the following formula (19) was used instead of the compound represented by formula (8); and 2.0 g of a compound represented by the following formula (20) was used instead of the compound represented by formula (10). Reference exampleThe same procedure as in 1 was carried out to obtain 4.9 g of the compound represented by the above formula (H) (in formula (H), mh representing the average degree of polymerization is 7.1).

[0164] [ka] (In formula (19), MOM represents a methoxymethyl group.)

[0165] [ka] (In formula (20), THP represents a tetrahydropyranyl group.)

[0166] The compound represented by formula (19) was synthesized by the following method. The primary hydroxyl group of 3-(4-pentenyloxy)-1,2-propanediol was protected with a tert-butyldimethylsilyl (TBS) group, and the secondary hydroxyl group of the resulting compound was protected with a methoxymethyl (MOM) group. The TBS group of the resulting compound was then removed, and the resulting compound was reacted with epibromohydrin to synthesize the compound.

[0167] The compound represented by formula (20) was synthesized by the following method. Allyl glycidyl ether was reacted with the primary hydroxyl group of hexahydro-1H-azepine-1-ethanol. The secondary hydroxyl group of the obtained compound was protected with a THP group, and the terminal double bond of the obtained compound was oxidized. The compound represented by formula (20) was obtained by the above steps.

[0168] The obtained compound (H) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR (CD3COCD3); δ[ppm]1.6~1.8(10H), 2.3~2.4(2H), 2.4~2.7(6H)3.4~4.2(32H), 5.1~5.2(1H), 5.2~5.3(1H), 5.8~5.9(1H) 19F-NMR (acetone-D6): δ[ppm]=-78.6(2F), -81.3(2F), -90.0~-88.5(28F)

[0169] ( Reference example 9) Reference example 1 of HOCH2CF2O(CF2CF2O) m (CF2O) n Instead of the compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5), HOCH2CF2CF2O(CF2CF2CF2O) p The following conditions were met: a compound (number average molecular weight: 1000, molecular weight distribution: 1.1) represented by CFCFCHOH (where p, which indicates the average degree of polymerization, is 4.4) was used; 6.6 g of the compound represented by the above formula (13) was used instead of the compound represented by formula (8); and 1.9 g of the compound represented by the following formula (21) was used instead of the compound represented by formula (10). Reference example The same procedure as in 1 was carried out to obtain 4.9 g of the compound represented by the above formula (I) (in formula (I), pi indicating the average degree of polymerization is 4.4).

[0170] [ka] (In formula (21), THP represents a tetrahydropyranyl group.)

[0171] The compound represented by formula (21) was synthesized by the following method. Allyl glycidyl ether was reacted with the primary hydroxyl group of 1-(3-hydroxypropyl)pyrrolidine. The secondary hydroxyl group of the obtained compound was protected with a THP group, and the terminal double bond of the obtained compound was oxidized. The compound represented by formula (21) was obtained by the above steps.

[0172] The obtained compound (I) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1H-NMR(CD3COCD3);δ[ppm]=1.7~1.8(2H), 1.8~1.9(4H), 2.5~2.8(7H), 3.4~4.2(36H) 19 F-NMR (acetone-D6): δ[ppm]=-84.0~-83.0(18F), -86.4(4F), -124.3(4F), -130.0~-129.0(9F)

[0173] (Comparative Example 1) The compound represented by the following formula (J) was synthesized by the following method. HOCH2CF2O(CF2CF2O) m (CF2O) n Using the method described in Patent Document 5, 4.12 g of a compound represented by the following formula (22) having a glycidyl group at the molecular terminal was obtained from 4.20 g of a compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (in the formula, m representing the average degree of polymerization is 4.5, and n representing the average degree of polymerization is 4.5).

[0174] Next, 40 mL of a dimethylamine aqueous solution (50% by mass) was added to the compound represented by formula (22), and the mixture was stirred at room temperature for 4 hours to react. The organic layer was separated from the reaction product obtained after the reaction, dissolved in 100 mL of Vertrel (registered trademark) XF, and dehydrated with anhydrous sodium sulfate. After filtering the desiccant, the filtrate was concentrated to synthesize 3.97 g (3.3 mmol) of compound (J).

[0175] [ka] (In formula (22), m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5.) (In formula (J), mj representing the average degree of polymerization is 4.5, and nj representing the average degree of polymerization is 4.5.)

[0176] The obtained compound (J) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CDCl3);δ[ppm]=2.3(12H), 2.4~2.5(4H), 3.4~4.2(12H) 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0177] (Comparative Example 2) The compound represented by the following formula (K) was synthesized by the method described in Patent Document 6.

[0178] [ka] (In formula (K), mk, which indicates the average degree of polymerization, is 4.5, and nk, which indicates the average degree of polymerization, is 4.5.)

[0179] The obtained compound (K) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CDCl3);δ[ppm]=3.5~4.0(20H), 5.1~5.3(4H), 5.9(2H) 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0180] (Comparative Example 3) The compound represented by the following formula (L) was synthesized by the method described in Patent Document 7.

[0181] [ka] (In formula (L), ml representing the average degree of polymerization is 4.5, and nl representing the average degree of polymerization is 4.5.)

[0182] The obtained compound (L) 1 H-NMR measurement and 19 F-NMR measurements were carried out and the structure was identified based on the following results. 1 H-NMR(CD3COCD3);δ[ppm]=1.6~1.8(4H), 3.1(2H), 3.5~4.2(21H), 5.1~5.3(2H), 5.9(1H) 19 F-NMR (CD3COCD3): δ[ppm]=-55.6~-50.6(9F), -77.7(2F), -80.3(2F), -91.0~-88.5(18F)

[0183] Comparative Example 4 The compound represented by the following formula (M) was synthesized by the method described in Patent Document 2.

[0184] [ka] (In formula (M), mm representing the average degree of polymerization is 4.5, and nm representing the average degree of polymerization is 4.5.)

[0185] The obtained compound (M) 1 H-NMR measurement was carried out, and the structure was identified from the following results. 1 H-NMR(CD3COCD3);δ[ppm]=3.5~4.3(23H), 5.1~5.3(2H), 5.9(1H), 6.2(1H), 7.3(1H)

[0186] (Comparative Example 5) The compound represented by the following formula (N) was synthesized by the following method. 2.5 g of trifluoromethanesulfonic acid chloride and 0.92 g of dimethylaminopyridine were added and stirred at -20°C. Then, HOCH2CF2O(CF2CF2O) m (CF2O) n 5.0 g of a compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (where m, which indicates the average degree of polymerization, is 4.5, and n, which indicates the average degree of polymerization, is 4.5) was added dropwise and reacted for 2 hours.

[0187] The reaction product obtained after the reaction was returned to room temperature, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated over anhydrous sodium sulfate. After filtering off the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography. By performing the above steps, 6.4 g (molecular weight 1264, 5.1 mmol) of the compound represented by the following formula (23) was obtained as an intermediate.

[0188] [ka] (In formula (23), m, which represents the average degree of polymerization, is 4.5, and n, which represents the average degree of polymerization, is 4.5.)

[0189] Under a nitrogen gas atmosphere, 6.0 g (molecular weight 1264.1, 4.8 mmol) of the intermediate compound represented by formula (23), 1.8 g (molecular weight 129.20, 14.2 mmol) of a commercially available compound represented by the following formula (24) (manufactured by UORSY, molecular weight 129.20, 14.2 mmol) and 12.4 mL of acetonitrile were placed in a 100 mL recovery flask, stirred at room temperature until homogenous, and then heated under reflux and stirring for 6 hours.

[0190] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of saturated sodium bicarbonate solution, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated using anhydrous sodium sulfate. After filtering off the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography. By performing the above steps, 4.0 g (3.3 mmol) of compound (N) (in formula (N), mn, which indicates the average degree of polymerization, is 4.5, and nn, which indicates the average degree of polymerization, is 4.5) was obtained.

[0191] [ka] (In formula (N), mn, which indicates the average degree of polymerization, is 4.5, and nn, which indicates the average degree of polymerization, is 4.5.)

[0192] The obtained compound (N) 1 H-NMR measurement was carried out, and the structure was identified from the following results. 1 H-NMR(CD3COCD3);δ[ppm]=1.6~1.8(6H), 2.3~2.4(4H), 2.5~2.8(12H), 3.5~4.1(6H), 5.4~5.5(4H)

[0193] This is how it was obtained Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 When the compound is applied to formula (1), R 1 The structure of the formula (3), a, z, [X], [Y], and R 3 The structure of R 4 The structure of R 5 The structure is shown in Table 1. Also, Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The number average molecular weights (Mn) of the compounds of Comparative Examples 1 to 5 were calculated using the above method. 1 H-NMR and 19 The results were obtained by F-NMR measurement, and are shown in Table 2.

[0194] [Table 1]

[0195] [Table 2]

[0196] Next, by the method shown below, Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 A solution for forming a lubricating layer was prepared using the compounds obtained in Comparative Examples 1 to 5. Then, the obtained solution for forming a lubricating layer was used to form a lubricating layer for a magnetic recording medium by the method described below. Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 Thus, magnetic recording media of Comparative Examples 1 to 5 were obtained.

[0197] "Lubricant layer forming solution" Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9The compounds obtained in Comparative Examples 1 to 5 were each dissolved in a fluorine-based solvent, Vertrel (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.), and diluted with Vertrel XF so that the film thickness when applied to the protective layer would be 9 Å to 10 Å, to prepare a solution for forming a lubricating layer.

[0198] "Magnetic recording media" A magnetic recording medium was prepared by sequentially depositing an adhesive layer, a soft magnetic layer, a first underlayer, a second underlayer, a magnetic layer, and a protective layer on a substrate having a diameter of 65 mm. The protective layer was made of carbon. On the protective layer of the magnetic recording medium on which each layer up to the protective layer has been formed, Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The lubricating layer-forming solutions of Comparative Examples 1 to 5 were each applied by dipping under the conditions of an immersion speed of 10 mm / sec, an immersion time of 30 seconds, and a pull-up speed of 1.2 mm / sec. The magnetic recording medium coated with the lubricating layer-forming solution was then placed in a thermostatic chamber at 120°C and heated for 10 minutes to remove the solvent in the lubricating layer-forming solution, thereby forming a lubricating layer on the protective layer and obtaining the magnetic recording medium. It was decided.

[0199] This is how it was obtained Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The thickness of the lubricating layer of the magnetic recording media of Comparative Examples 1 to 5 was measured using an FT-IR (product name: Nicolet iS50, manufactured by Thermo Fisher Scientific). The results are shown in Table 2.

[0200] next, Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The magnetic recording media of Comparative Examples 1 to 5 were subjected to the following wear resistance test. (Wear resistance test) Using a pin-on-disk friction and wear tester, a 2 mm diameter alumina ball was slid on the lubricating layer of the magnetic recording medium at a load of 40 gf and a sliding speed of 0.25 m / sec to measure the friction coefficient of the surface of the lubricating layer. The sliding time until the friction coefficient of the surface of the lubricating layer suddenly increased was then measured. The sliding time until the friction coefficient suddenly increased was measured four times for the lubricating layer of each magnetic recording medium, and the average value (time) was used as an index of the wear resistance of the lubricant coating (time until the friction coefficient increased). Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The results for the magnetic recording media using the compounds of Comparative Examples 1 to 5 are shown in Table 2. The time until the friction coefficient increases was evaluated as follows: The longer the time it takes for the friction coefficient to increase sharply, the better the wear resistance, and therefore the more preferable it is.

[0201] "Evaluation Criteria" A:850sec or more B: 750 seconds or more, less than 850 seconds C: 650 seconds or more, less than 750 seconds D: 550 seconds or more, less than 650 seconds E: 450 seconds or more, less than 550 seconds

[0202] The time until the coefficient of friction increases sharply can be used as an indicator of the wear resistance of the lubricating layer for the following reason: The lubricating layer of a magnetic recording medium wears away as the magnetic recording medium is used, and when the lubricating layer is worn away, the contact and protective layer come into direct contact, causing a sharp increase in the coefficient of friction. The time until the coefficient of friction increases sharply is thought to correlate with friction tests.

[0203] As shown in Table 2, the lubricating layer contains the compound represented by formula (1). Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The magnetic recording medium of this invention had good wear resistance. Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 R in the compound 1 The alkenyl or alkynyl group of R exhibits good interaction with the protective layer, and 5 Tertiary amine (-NR 6 R 7) has a suitable bulkiness, which is presumed to have enabled the coating rate with respect to the protective layer to be maintained at an appropriate level without impairing the adhesion to the protective layer.

[0204] In contrast, as shown in Table 2, the magnetic recording media of Comparative Examples 1 to 5 have the following characteristics: Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The results show that the wear resistance is inferior compared to the compounds in Comparative Examples 1 to 5. This is presumably because the lubricating layers containing the compounds in Comparative Examples 1 to 5 are less likely to adhere to the protective layer.

[0205] next, Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The compounds of Comparative Examples 1 to 5 were subjected to the following heat resistance test. (Heat resistance test) Using a thermogravimetric differential thermal analyzer (TG-DTA) (manufactured by Bruker, product name: Galaxy), Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The compounds of Comparative Examples 1 to 5 were subjected to thermal decomposition measurements under nitrogen and under air. The results are shown in Table 2. The exothermic onset temperature was evaluated as follows. Note that a higher exothermic onset temperature is preferable because it indicates better heat resistance.

[0206] "Evaluation Criteria" A: 240℃ or higher B: 200℃ or higher, less than 240℃ C: 180℃ or higher, less than 200℃ D: 140℃ or higher, less than 180℃ E: Less than 140℃

[0207] As shown in Table 2, the compound represented by formula (1) Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The heat generation starting temperature was high under nitrogen and in air, and the heat resistance was good. 5 Tertiary amine (-NR 6 R 7 ) acts as a radical scavenger, 1 This is presumably because the heat resistance of the alkenyl or alkynyl group in the compound (I) has improved, making it less susceptible to oxidative decomposition due to heat. Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 From the results, the tertiary amine (-NR 6 R 7It was confirmed that when the group represented by the formula (I) is a morpholine group, particularly excellent heat resistance can be obtained.

[0208] As shown in Table 2, the compounds of Comparative Examples 1 and 5 showed no difference in exothermic onset temperature between under nitrogen and under air, and exhibited heat resistance comparable to that of Examples. This is presumably because the compounds of Comparative Examples 1 and 5 contain a tertiary amine. In contrast, the compounds of Comparative Examples 2 and 3, which did not have a tertiary amine but had an alkenyl group, showed poor heat resistance. This is presumably because the alkenyl group in the compounds of Comparative Examples 2 and 3 was oxidatively decomposed by heat.

[0209] In addition, Comparative Example 4 showed heat resistance under nitrogen at the same level as in Examples, but the exotherm onset temperature under air was low, resulting in poor heat resistance. This is presumably because the unsaturated heterocycle having a nitrogen atom was decomposed by heat, resulting in a decrease in the radical-capturing function of the unsaturated heterocycle having a nitrogen atom.

[0210] Also, Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9 The compounds and magnetic recording media of Comparative Examples 1 to 5 were comprehensively evaluated based on the following criteria. The results are shown in Table 2. "Evaluation Criteria" A: A or B in the abrasion resistance test and A in the heat resistance test (in air) B: A or B in the abrasion resistance test, and B in the heat resistance test (in air). C: Abrasion resistance test rating of C and heat resistance test (in air) rating of A to C D: The abrasion resistance test was rated C, and the heat resistance test (in air) was rated D or E, or the abrasion resistance test was rated D or E, and the heat resistance test (in air) was rated A to C. E: Abrasion resistance test rating of D or E, and heat resistance test (in air) rating of D or E

[0211] As shown in Table 2, the compound represented by formula (1) was used. Examples 4 and 7, Reference Examples 1 to 3, 5, 6, 8, and 9The overall evaluation was A or B. In contrast, the overall evaluations of Comparative Example 1 and Comparative Examples 3 to 5 were D, and the overall evaluation of Comparative Example 2 was E. [Industrial Applicability]

[0212] The present invention provides a fluorine-containing ether compound suitable as a material for a lubricant for a magnetic recording medium, which is capable of forming a lubricating layer having excellent wear resistance and heat resistance. By using a lubricant for magnetic recording media containing the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer that can achieve excellent wear resistance and heat resistance even if it is thin. [Explanation of symbols]

[0213] 10...magnetic recording medium, 11...substrate, 12...adhesion layer, 13...soft magnetic layer, 14...first underlayer, 15...second underlayer, 16...magnetic layer, 17...protective layer, 18...lubricating layer.

Claims

1. A fluorine-containing ether compound represented by the following formula (1): R １ -O-R ２ -CH ２ -R ３ -CH ２ -R ４ -R ５ (1) (In formula (1), R ３ is a perfluoropolyether chain; R １ is an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 3 to 8 carbon atoms; R ２ , R ４ are each independently a divalent linking group containing one or more hydroxyl groups; -R ５ is a group represented by the following formula (2): -O-(CH ２ ) ｇ -N-R ６ R ７ (2) (In formula (2), g is an integer of 2 or 3; R ６ and R ７ are the same or different saturated aliphatic groups; -NR 6 R 7 is an acyclic amine.

2. -R in the formula (1) ２ 2. The fluorine-containing ether compound according to claim 1, wherein - is represented by the following formula (3): -((CH ２ ) ａ -O) ｚ -[X]-[Y]- (3) (In formula (3), a represents an integer of 1 to 3, z represents 0 or 1; [X] is represented by the following formula (X), [Y] is represented by the following formula (Y), and the bonding order of [X] and [Y] may be reversed; however, the sum of c in formula (X) and e in formula (Y) is 1 or 2.) 【Chemical 1】 (In formula (X), b is an integer of 1 to 3, and c is an integer of 0 to 2.) (In formula (Y), d is an integer of 2 to 3, and e is an integer of 0 to 2.)

3. -R in the formula (1) ４ 3. The fluorine-containing ether compound according to claim 1, wherein - is represented by the following formula (4): 【Chemistry 2】 (In formula (4), f is an integer of 1 to 2.)

4. The R ２ and the hydroxyl group contained in the R ４ The fluorine-containing ether compound according to any one of claims 1 to 3, wherein the total number of hydroxyl groups contained in

5. R in the formula (2) ６ and R ７ The fluorine-containing ether compound according to any one of claims 1 to 4, wherein each of the groups independently represents a saturated aliphatic group having 1 to 4 carbon atoms.

6. -N-R in the formula (2) ６ R ７ The fluorine-containing ether compound according to any one of claims 1 to 4, wherein is a dimethylamino group or a diethylamino group.

7. R in the formula (1) １ The fluorine-containing ether compound according to any one of claims 1 to 6, wherein is any one group selected from a vinyl group, an allyl group, a 3-butenyl group, a 4-pentenyl group, and a propargyl group.

8. The R ３ The fluorine-containing ether compound according to any one of claims 1 to 7, wherein is represented by any one of the following formulas (5) to (7): -CF ２ O-(CF ２ CF ２ O) ｈ -(CF ２ O) ｉ -CF ２ - (5) (In formula (5), h and i represent the average degree of polymerization, each representing 0 to 30; however, h and i cannot be 0 at the same time.) -CF(CF ３ )-(OCF(CF ３ )CF ２ ) ｊ -OCF(CF ３ )- (6) (In formula (6), j represents the average degree of polymerization and is 0.1 to 30.) -CF ２ CF ２ O-(CF ２ CF ２ CF ２ O) ｋ -CF ２ CF ２ - (7) (In formula (7), k represents the average degree of polymerization and is 0.1 to 30.)

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

10. A lubricant for magnetic recording media, comprising the fluorine-containing ether compound according to any one of claims 1 to 9.

11. A magnetic recording medium having at least a magnetic layer, a protective layer, and a lubricating layer sequentially provided on a substrate, 10. A magnetic recording medium, wherein the lubricating layer contains the fluorine-containing ether compound according to claim 1.

12. 12. The magnetic recording medium according to claim 11, wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm.

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