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

Abstract

The present application is a fluorine-containing ether compound represented by the following formula. R 1 -R 2 -CH2-R 3 [ -CH2-R 4 -CH2-R 3’ ] n -CH2-R 5 -R 6 (n is 1 or 2; R 3 and R 3’ are perfluoropolyether chains; R 4 is a divalent linking group having 1 polar group; R 2 and R 5 are divalent linking groups having 1 or more polar groups; R 2 the terminal on the side bonded to R 1 , R 5 the terminal on the side bonded to R 6 is an oxygen atom; R 1 and R 6 are terminal groups bonded to the terminal oxygen atom of R 2 or R 5 ; R 1 and R 6 are organic groups having 1 to 50 carbon atoms, and at least one is a group having a carbonyl carbon atom or a nitrogen atom constituting an amide bond bonded to a carbon atom of an organic group having 1 to 8 carbon atoms.)

Description

TECHNICAL FIELD

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

[0002] This application claims priority based on Japanese Patent Application No. 2021-143417 filed on September 2, 2021, the contents of which are incorporated herein. BACKGROUND

[0003] In order to improve the recording density of a magnetic recording and reproducing device, development of a magnetic recording medium suitable for high recording density is being carried out.

[0004] In the past, as a magnetic recording medium, there has been a magnetic recording medium obtained by forming a recording layer on a substrate and forming a protective layer of carbon or the like on the recording layer. The protective layer protects information recorded in the recording layer and improves the slidability of a magnetic head. However, by merely providing the protective layer on the recording layer, the durability of the magnetic recording medium cannot be sufficiently obtained. Therefore, a lubricating layer is usually formed by applying a lubricant to the surface of the protective layer.

[0005] As a lubricant used when forming a lubricating layer of a magnetic recording medium, for example, a lubricant containing a compound having a polar group such as a hydroxyl group or an amino group at the terminal of a fluorine-based polymer having a repeating structure containing -CF2- is proposed.

[0006] For example, in Patent Literature 1 and Patent Literature 2, a fluoropolyether compound is disclosed in which a perfluoropolyether is bonded to both sides of an aliphatic hydrocarbon chain having a hydroxyl group present in the central portion of the molecule.

[0007] In addition, in Patent Literature 3, a fluoropolyether compound is disclosed in which a plurality of perfluoropolyether groups are connected by an aliphatic hydrocarbon group having a hydroxyl group.

[0008] In addition, in Patent Literature 4, a fluorine-containing ether compound is disclosed in which a divalent linking group having a polar group is connected to both terminals of a perfluoropolyether chain, and one or more hydrogens of a chain organic group having 1 to 8 carbon atoms bonded to at least one of the terminal groups are substituted with a terminal group having an amide bond.

[0009] PRIOR ART DOCUMENTS

[0010] PATENT LITERATURE

[0011] Patent Literature 1: U.S. Patent No. 10540997

[0012] Patent Literature 2: Japanese Patent No. 6804981

[0013] Patent Literature 3: Japanese Patent No. 6763980

[0014] Patent Literature 4: International Publication No. 2019 / 039265

[0015] Patent Literature 5: International Publication No. 2017 / 154403 SUMMARY

[0016] PROBLEMS TO BE SOLVED BY THE INVENTION

[0017] In a magnetic recording and reproducing apparatus, it is required to further reduce the flying height of a magnetic head. Therefore, it is necessary to make the thickness of a lubricating layer in a magnetic recording medium thinner.

[0018] However, there is generally a tendency that if the thickness of the lubricating layer is made thinner, the chemical resistance and the wear resistance of the magnetic recording medium are reduced. In addition, if the thickness of the lubricating layer is made thinner, sometimes the corrosion resistance of the magnetic recording medium becomes insufficient. Thus, a lubricating layer having excellent chemical resistance and wear resistance, and high effect of suppressing corrosion of the magnetic recording medium is required.

[0019] The present application has been made in view of the above circumstances, and an object thereof is to provide a fluorine-containing ether compound which can form a lubricating layer having excellent chemical resistance and wear resistance, and high effect of suppressing corrosion of the magnetic recording medium, and which can be suitably used as a material of a lubricant for a magnetic recording medium.

[0020] In addition, an object of the present application is to provide a lubricant for a magnetic recording medium which contains the fluorine-containing ether compound of the present application, and which can form a lubricating layer having good chemical resistance and wear resistance, and excellent corrosion resistance.

[0021] In addition, an object of the present application is to provide a magnetic recording medium which has a lubricating layer containing the fluorine-containing ether compound of the present application, and which has good chemical resistance and wear resistance, and excellent corrosion resistance.

[0022] MEANS FOR SOLVING THE PROBLEMS

[0023] The present application includes the following modes.

[0024] The first mode of the present application provides the following fluorine-containing ether compound.

[0025] [1] A fluorine-containing ether compound characterized by being represented by the following formula (1).

[0026] R 1 -R 2 -CH2-R 3 [-CH2-R 4 -CH2-R 3’ ] n -CH2-R5 -R 6 (1)

[0027] (In formula (1), n is 1 or 2; R 3 and R 3’ are perfluoropolyether chains; R 3 and one or two R 3’ may be partially the same or all the same, or each can be different; R 4 is a divalent linking group having one polar group; in the case where n is 2, the two R 4 may be the same or different; R 2 and R 5 are divalent linking groups having one or more polar groups, R 2 and R 5 may be the same or different; R 2 of the end on the side bonded to R 1 is an oxygen atom; R 5 of the end on the side bonded to R 6 is an oxygen atom; R 1 and R 6 are terminal groups bonded to the terminal oxygen atom of R 2 or R 5 , R 1 and R 6 may be the same or different; R 1 and R 6 are organic groups having 1 to 50 carbon atoms, and at least one is a group having a carbonyl carbon atom or a nitrogen atom constituting an amide bond bonded to a carbon atom of an organic group having 1 to 8 carbon atoms.)

[0028] The fluorine-containing ether compound of the first aspect of the present application preferably has the features described in [2] to

[11] below. The features described in [2] to

[11] below are also preferably combined with two or more features arbitrarily.

[0029] [2] The fluorine-containing ether compound according to [1], wherein at least one of R 1 and R 6 in formula (1) is a group having a carbonyl carbon atom or a nitrogen atom constituting an amide bond bonded to a carbon atom of a phenyl group or an alkyl group having 1 to 6 carbon atoms.

[0030] [3] The fluorine-containing ether compound according to [1] or [2], wherein the polar groups of R 2 , R 4 and R 5 in formula (1) are all hydroxyl groups.

[0031] [4] The fluorine-containing ether compound according to [3], wherein R 2 has a total number of 2 to 6 of hydroxyl groups. 5 has a total number of 2 to 6 of hydroxyl groups.

[0032] [5] The fluorine-containing ether compound according to any one of [1] to [4], wherein R 1 and R 6 is a group having a carbonyl carbon atom or a nitrogen atom constituting an amide bond bonded to a carbon atom of a phenyl group or an alkyl group having 1 to 6 carbon atoms.

[0033] [6] The fluorine-containing ether compound according to any one of [1] to [5], wherein R 2 is a linking group represented by the following formula (2-1) or (2-2),

[0034] R 5 is a linking group represented by the following formula (2-3) or (2-4).

[0035]

[0036] (In formula (2-1), p1 represents an integer of 1 to 3.)

[0037] (In formula (2-2), q1 represents an integer of 2 to 4.)

[0038] (In formula (2-3), p2 represents an integer of 1 to 3.)

[0039] (In formula (2-4), q2 represents an integer of 2 to 4.)

[0040] [7] The fluorine-containing ether compound according to any one of [1] to [6], wherein R 3 and 1 or 2 R 3’ are all the same, and R 1 - R 2 - R 6 - R 5 - are the same.

[0041] [8] The fluorine-containing ether compound according to any one of [1] to [7], wherein R 4 is a linking group represented by any one of the following formulas (3-1) to (3-3).

[0042]

[0043] (In formula (3-2), r is an integer of 2 to 4.)

[0044] (In formula (3-3), s is an integer of 2 to 4.)

[0045] [9] The fluorine-containing ether compound according to any one of [1] to [8], wherein R 3 and one or two R 3’ each independently represents a perfluoropolyether chain represented by the following formula (4).

[0046] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0047] (In formula (4), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein, the case where w2, w3, w4, and w5 are all 0 at the same time is excluded; wl and w6 are average values representing the number of CF2, and each independently represents 1 to 3; the arrangement order of the repeating units in formula (4) is not particularly limited.)

[0048]

[10] The fluorine-containing ether compound according to any one of [1] to [9], wherein R 3 and one or two R 3’ each independently represents any one perfluoropolyether chain selected from the group consisting of perfluoropolyether chains represented by the following formulas (4-1) to (4-4).

[0049] -CF2-(OCF2CF2) h -(OCF2) i -OCF2- (4-1)

[0050] (In formula (4-1), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0051] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2- (4-2)

[0052] (In formula (4-2), j represents an average polymerization degree, and represents 1 to 15.)

[0053] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2- (4-3)

[0054] (In formula (4-3), k represents an average polymerization degree, and represents 1 to 10.)

[0055] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 - (4-4)

[0056] (In formula (4-4), w8, w9 represent average polymerization degrees, each independently represents 1 to 20; w7, w10 are average values representing the number of CF2, each independently represents 1 to 2.)

[0057]

[11] The fluorine-containing ether compound according to any one of [1] to

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

[0058] A second aspect of the present application provides the following lubricant for a magnetic recording medium.

[0059]

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

[11] .

[0060] A third aspect of the present application provides the following magnetic recording medium.

[0061]

[13] A magnetic recording medium, characterized by being a magnetic recording medium in which a magnetic layer, a protective layer, and a lubricating layer are provided in this order on a substrate,

[0062] The lubricating layer contains the fluorine-containing ether compound according to any one of [1] to

[11] .

[0063] The magnetic recording medium of the third aspect of the present application preferably has the features described in

[14] below.

[0064]

[14] The magnetic recording medium according to

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

[0065] Effects of the Invention

[0066] The fluorine-containing ether compound of the present application is a compound represented by the above formula (1), and is suitable as a material for a lubricant for a magnetic recording medium.

[0067] The lubricant for a magnetic recording medium of the present application contains the fluorine-containing ether compound of the present application, and thus, a lubricating layer having high effects of good chemical resistance and wear resistance, and high corrosion inhibition of the magnetic recording medium can be formed.

[0068] The magnetic recording medium of the present invention has a lubricating layer comprising the fluorinated ether compound of the present invention. Therefore, the magnetic recording medium of the present invention exhibits good chemical resistance and abrasion resistance, excellent corrosion resistance, and superior reliability and durability. Furthermore, the lubricating layer of the magnetic recording medium of the present invention has good chemical resistance and abrasion resistance, and is highly effective in inhibiting corrosion of the magnetic recording medium, thus enabling a reduction in thickness. Attached Figure Description

[0069] [ Figure 1 This is a schematic cross-sectional view illustrating a preferred embodiment of the magnetic recording medium of the present invention. Detailed Implementation

[0070] In order to solve the above-mentioned problems, the inventors of this application have repeatedly conducted in-depth research as shown below.

[0071] Conventionally, fluorinated ether compounds having polar groups such as hydroxyl groups at the ends of their chain structures are preferred as materials for lubricants (hereinafter sometimes simply referred to as "lubricants") used as coatings on the surface of protective layers for magnetic recording media. The polar groups in the fluorinated ether compounds bond to active sites on the protective layer, thereby improving the adhesion of the lubricant layer to the protective layer. Therefore, fluorinated ether compounds having polar groups not only at the ends of their chain structures but also within the chain structure itself are particularly preferred as lubricant materials.

[0072] However, when using conventional lubricants to form a thin lubricating layer on the protective layer, it is difficult to achieve a lubricating layer with good chemical resistance, wear resistance, and excellent corrosion resistance, as shown below.

[0073] In other words, if the lubricant does not adhere sufficiently to the protective layer, the lubricant applied to the protective layer becomes loose. Therefore, the coating of the lubricant layer onto the protective layer tends to become uneven. If the coating of the lubricant layer is uneven, its chemical resistance and corrosion resistance become insufficient. Therefore, if the film thickness is not increased to ensure uniform coating of the lubricant layer onto the protective layer when the adhesion of the lubricant layer is insufficient, adequate chemical resistance and corrosion resistance cannot be obtained.

[0074] As a method to improve the adhesion of the lubricant to the protective layer, a fluorinated ether compound with polar groups bonded to the last carbon atom at one end of the chain structure, the carbon atom bonded to the last carbon atom, and the carbon atoms in the other chain structures can be considered as the material of the lubricant.

[0075] However, lubricating layers formed using such fluorinated ether compounds sometimes suffer from impaired lubricity and insufficient wear resistance due to excessive adhesion between the lubricating layer and the protective layer.

[0076] In addition, in the case of a lubricating layer formed using such a fluorine-containing ether compound, corrosion of the magnetic recording medium is sometimes observed due to easy intrusion of water because the lubricant has too high hydrophilicity.

[0077] The adhesion of the lubricant to the protective layer can be adjusted, for example, by changing the heat treatment temperature in the heat treatment, which is performed as necessary after the application of the lubricant containing the fluorine-containing ether compound to the protective layer. Specifically, the adhesion of the lubricant to the protective layer becomes stronger as the heat treatment temperature is increased, and becomes weaker as the heat treatment temperature is decreased.

[0078] Therefore, in the case where the adhesion of the lubricant to the protective layer is too strong, the adhesion of the lubricating layer to the protective layer can be weakened by, for example, decreasing the heat treatment temperature, so that the adhesion of the lubricating layer to the protective layer is made to be an appropriate strength, thereby improving the wear resistance of the lubricating layer.

[0079] However, in the case of a lubricating layer formed using a fluorine-containing ether compound in which a polar group is bonded to each of the terminal carbon atom of the chain structure, a carbon atom bonded to the terminal carbon atom, and a carbon atom other than these in the chain structure, if the adhesion of the lubricating layer to the protective layer is made weak by the above method, the chemical resistance and the corrosion resistance of the lubricating layer deteriorate. It is inferred that this is because the proportion of the polar groups in the fluorine-containing ether compound that do not participate in the bonding to the active sites on the protective layer increases. That is, it is inferred that the polar groups in the fluorine-containing ether compound that do not participate in the bonding to the active sites on the protective layer induce environmental substances that generate contaminants, water that is a cause of corrosion of the magnetic recording medium, to the lubricating layer, and deteriorate the chemical resistance of the lubricating layer and the corrosion resistance of the magnetic recording medium.

[0080] Therefore, the inventors of the present application focused on the bonding of the polar groups contained in the fluorine-containing ether compound to the active sites on the protective layer. Also, in order to achieve a fluorine-containing ether compound that is less likely to generate polar groups that do not participate in the bonding to the active sites on the protective layer, can form a lubricating layer that has excellent adhesion to the protective layer, good chemical resistance and wear resistance, and a high effect of suppressing corrosion of the magnetic recording medium, intensive studies were repeatedly conducted.

[0081] As a result, it was found that a fluorine-containing ether compound having a skeleton in which a plurality of perfluoropolyether chains are bonded via a linking group having one polar group, 2-valent linking groups having polar groups, and terminal groups that are organic groups having 1 to 50 carbon atoms are sequentially bonded to both sides thereof via methylene groups (-CH2-), at least one of the terminal groups being a group in which a carbonyl carbon atom or a nitrogen atom that constitutes an amide bond is bonded to a carbon atom of an organic group having 1 to 8 carbon atoms, can be used.

[0082] In such a fluorine-containing ether compound, the polar group not bonded to the functional group (active site) present in a large amount on the protective layer is less likely to be generated for the following reasons. Also, in such a fluorine-containing ether compound, the polar group possessed by the amide contained in at least one terminal group and the divalent linking group independently exhibits a good interaction with the protective layer for the following reasons, and is independently capable of being bonded to the functional group (active site) present in a large amount on the protective layer. It is thus inferred that the above-described fluorine-containing ether compound is capable of forming a lubricating layer having a good adhesion to the protective layer, and is capable of forming a lubricating layer having a good chemical resistance and wear resistance, and a high effect of suppressing corrosion of the magnetic recording medium.

[0083] That is, in the above-described fluorine-containing ether compound, an amide bond is contained in at least one terminal group. The bond possessed by the carbon atom adjacent to the carbonyl carbon atom or the nitrogen atom constituting the amide bond of the terminal group is less likely to freely rotate. Therefore, the amide contained in at least one terminal group and the polar group possessed by the divalent linking group in the fluorine-containing ether compound are less likely to interact with each other. Therefore, the ability of the amide contained in at least one terminal group and the polar group possessed by the divalent linking group in the fluorine-containing ether compound to hinder the interaction between each other and the protective layer is extremely low.

[0084] In addition, in the above-described fluorine-containing ether compound, a perfluoropolyether chain is disposed between the divalent linking groups in the fluorine-containing ether compound, respectively. Therefore, the distance between the polar groups possessed by the adjacent divalent linking groups is appropriate. Also, at least one terminal group is an organic group having an amide bond which is less likely to freely rotate. Due to these reasons, the bonding of the polar group possessed by the divalent linking group in the fluorine-containing ether compound to the active site on the protective layer is not hindered by the amide contained in at least one terminal group or the polar group possessed by the adjacent divalent linking group.

[0085] It is thus considered that, in the above-described fluorine-containing ether compound, the amide contained in at least one terminal group and the polar group possessed by the divalent linking group do not hinder the bonding to the active site on the protective layer from each other, and each easily participates in the bonding to the active site on the protective layer. As a result, the polar group not bonded to the active site on the protective layer is less likely to be generated, and the amount of the polar group not participating in the bonding to the active site on the protective layer can be suppressed. Also, in the above-described fluorine-containing ether compound, the amide contained in at least one terminal group and the polar group possessed by the divalent linking group do not hinder the bonding to the active site on the protective layer from each other, and each independently exhibits a good interaction with the protective layer. As a result, the amide contained in at least one terminal group and the polar group possessed by the divalent linking group are each independently capable of being bonded to the functional group (active site) present in a large amount on the protective layer.

[0086] Further, in the above-mentioned fluorine-containing ether compound, the distance between the polar groups possessed by the divalent linking group is appropriate, and thus the polar groups possessed by the divalent linking group are not easily aggregated with each other. Also, the both end portions of each perfluoropolyether chain are respectively bonded to the protective layer by the polar groups possessed by the divalent linking group. Therefore, the state of the fluorine-containing ether compound coated on the protective layer is not easily made bulky, the fluorine-containing ether compound easily spreads on the protective layer, and a lubricating layer having a uniform coating state is easily obtained. Thus, it is inferred that the above-mentioned fluorine-containing ether compound can form a lubricating layer which is excellent in chemical resistance and wear resistance, and which is high in effect of suppressing corrosion of the magnetic recording medium.

[0087] Further, the inventors of the present application have confirmed that by using a lubricant containing the above-mentioned fluorine-containing ether compound, a lubricating layer which is excellent in chemical resistance and wear resistance, and which is excellent in corrosion resistance can be formed, and thus have conceived the present application.

[0088] Hereinafter, examples of the fluorine-containing ether compound, the lubricant for a magnetic recording medium, and the magnetic recording medium according to the present application will be described in detail. Note that the present application is not limited only to the following embodiments. The present application can be added, omitted, replaced, changed in number, amount, ratio, material, constitution, and the like without departing from the gist of the present application.

[0089] [Fluorine-containing ether compound]

[0090] A fluorine-containing ether compound characterized by being represented by the following formula (1).

[0091] R 1 -R 2 -CH2-R 3 [-CH2-R 4 -CH2-R 3’ ] n -CH2-R 5 -R 6 (1)

[0092] (In formula (1), n is 1 or 2; R 3 and R 3’ are perfluoropolyether chains; R 3 and one or two R 3’ may be partially the same or entirely the same, or each can be different; R 4 is a divalent linking group having one polar group; in the case where n is 2, the two R 4 may be the same or different; R 2 and R 5 are divalent linking groups having one or more polar groups, and R 2 and R 5 may be the same or different; R2 R 1 bonded to the terminal of R 5 bonded to the terminal of R 6 bonded to the terminal of R 1 and R 6 are terminal groups bonded to the terminal oxygen atom of R 2 or R 5 ; R 1 and R 6 may be the same or different; R 1 and R 6 are organic groups having 1 to 50 carbon atoms, and at least one is a group bonded to a carbon atom of an organic group having 1 to 8 carbon atoms, a carbonyl carbon atom or a nitrogen atom constituting an amide bond.

[0093] The fluorine-containing ether compound of the present embodiment has a linking structure in which a methylene group, a divalent linking group having 1 polar group represented by R 4 is sequentially bonded to R 3 and R 3’ , and a plurality of perfluoropolyether chains (hereinafter, sometimes referred to as "PFPE chains") represented by R 2 and R 5 are linked to the skeleton. On both sides of the skeleton, a methylene group, a divalent linking group having 1 or more polar groups represented by R 1 and R 6 , and terminal groups represented by R 1 and R 6 are sequentially bonded. Also, at least one of the terminal groups in R 1 and R 6 is a group bonded to a carbon atom of an organic group having 1 to 8 carbon atoms, a carbonyl carbon atom or a nitrogen atom constituting an amide bond (hereinafter, sometimes referred to as "terminal group having an amide bond").

[0094] In the fluorine-containing ether compound of the present embodiment, the number n of the repeating unit in formula (1), that is, [-CH2-R 4 -CH2-R 3’ ], is 1 or 2. In the case where n is 1, the skeleton having 2 PFPE chains represented by R 3 and R 3’ is arranged on both sides of a divalent linking group having 1 polar group represented by R 4 as the center via a methylene group. Therefore, it becomes a fluorine-containing ether compound which easily spreads uniformly on the protective layer to be infiltrated, and thus it is preferable to easily obtain a lubricating layer having a uniform film thickness. In the case where n is 2, the skeleton having 2 PFPE chains represented by R 4 is arranged on both sides of a linking group represented by R 3’ and a PFPE chain (R3 Or R 3’ The framework of the fluorinated ether compound is as follows: Therefore, a fluorinated ether compound is preferred as it is easy to uniformly wet and spread on the protective layer, thus easily obtaining a lubricating layer with a uniform film thickness. n can be suitably determined according to the intended use of the fluorinated ether compound, etc.

[0095] (R 4 (representing a divalent linker)

[0096] In the fluorinated ether compound represented by formula (1), R 4 It is a divalent linker with one polar group. R 4 Configured in R 3 and 1 or 2 R 3’ The PFPE chains are represented. Therefore, R 4 This allows the fluorinated ether compound to adhere tightly to the protective layer, forming a thinner lubricating layer with sufficient coverage.

[0097] The repeating unit in equation (1) is [-CH2-R 4 -CH2-R 3’ When the quantity n is 2, there are 2 R 4 They can be the same or different. If two Rs... 4 If the coating is the same, the fluorinated ether compound will result in a more uniform coating of the protective layer, forming a lubricating layer with better adhesion.

[0098] In this manual, the term "2 Rs" refers to... 4 "Same" refers to the two R's that are present in fluorinated ether compounds. 3’ R is disposed at the center of the fluorinated ether compound represented by formula (1). 3’ In terms of 2 Rs 4 The atoms contained therein are arranged in a symmetrical configuration.

[0099] R 4 The divalent linker group is preferably provided with oxygen atoms at both ends. The oxygen atoms at both ends of the linker group and the oxygen atoms at the R... 4 The methylene groups (-CH2-) on both sides form ether bonds (-O-). These two ether bonds impart moderate flexibility to the fluorinated ether compound represented by formula (1), making R... 4 The polar groups of the divalent linker exhibit increased affinity for the protective layer.

[0100] R 4The divalent linking group represented by R<2> is preferably a group in which one polar group is bonded to a carbon atom of an alkylene group having 3 to 6 carbon atoms, and both end portions are oxygen atoms. As the alkylene group having 3 to 6 carbon atoms, an alkylene group having 3 to 4 carbon atoms is preferable. The alkylene group having 3 to 6 carbon atoms preferably has a straight chain structure. R 4 It is particularly preferable that the polar group be bonded to a carbon atom in the vicinity of the center of the alkylene group having 3 to 6 carbon atoms in a straight chain. This is because the fluorine-containing ether compound becomes more uniform in the coated state of the protective layer, and a lubricating layer having a better adhesion property is formed.

[0101] As the polar group possessed by R 4 , for example, a hydroxyl group (-OH), an amino group (-NH2), a carboxyl group (-COOH), an aldehyde group (-COH), a carbonyl group (-CO-), a sulfonic acid group (-SO3H), and the like can be given. Among them, it is particularly preferable that the polar group be a hydroxyl group. The interaction between the hydroxyl group and the protective layer, particularly the protective layer formed of a carbon-based material, is large. Therefore, if R 4 possesses a hydroxyl group as the polar group, the adhesion of the lubricating layer containing the fluorine-containing ether compound to the protective layer becomes higher. In the case where n is 2, two R 4 each have one polar group, it is preferable that at least one be a hydroxyl group, and more preferably both be hydroxyl groups.

[0102] In the fluorine-containing ether compound represented by formula (1), R 4 is a divalent linking group having one polar group, and therefore, compared with, for example, a fluorine-containing ether compound containing a divalent linking group having two or more polar groups instead of R 4 , a lubricating layer containing the same can sufficiently obtain an effect of inhibiting corrosion of a magnetic recording medium. This is because the hydrophilicity of the fluorine-containing ether compound is not excessively high, and the invasion of water, which is a cause of corrosion of the magnetic recording medium, into the lubricating layer containing the same can be inhibited.

[0103] Specifically, R 4 is preferably any one of the following formulas (3-1) to (3-3). In formulas (3-1) to (3-3), the left-side oxygen atom is bonded to one of the two methylene groups bonded to R 4 , and the right-side oxygen atom is bonded to the other methylene group. 2 5

[0104] If R 4 is any one of formulas (3-1) to (3-3), the fluorine-containing ether compound represented by formula (1) is easy to synthesize, and is therefore preferable. In particular, if R 4 is formula (3-1), the fluorine-containing ether compound represented by formula (1) is more easy to synthesize, and is therefore preferable. ​​

[0105]

[0106] (In formula (3-2), r is an integer of 2 to 4.)

[0107] (In formula (3-3), s is an integer of 2 to 4.)

[0108] In formula (3-2), r is an integer of 2 to 4, preferably an integer of 2 to 3, and more preferably 2. This is because the coating state of the fluorine-containing ether compound to the protective layer becomes more uniform, and a lubricating layer having a better adhesion is formed.

[0109] In formula (3-3), s is an integer of 2 to 4, preferably an integer of 2 to 3, and more preferably 2. This is because the coating state of the fluorine-containing ether compound to the protective layer becomes more uniform, and a lubricating layer having a better adhesion is formed.

[0110] The linking group represented by formula (3-2) or (3-3) has a structure in which 1 to 3 methylene groups are added to the skeleton (-OCH2CH(OH)CH2O-) of glycerol. Therefore, R 4 The lubricating layer of the fluorine-containing ether compound of formula (3-2) or (3-3) becomes a lubricating layer having a good hydrophobicity. As a result, it is possible to effectively prevent the invasion of water, which is a cause of corrosion of the magnetic recording medium, and to form a lubricating layer having a high effect of suppressing corrosion of the magnetic recording medium.

[0111] (R 3 and R 3’ representing a PFPE chain)

[0112] In the fluorine-containing ether compound represented by formula (1), R 3 and R 3’ are perfluoropolyether chains. R 3 and R 3’ representing a PFPE chain in the case where a lubricant containing the fluorine-containing ether compound of the present embodiment is applied to the protective layer to form a lubricating layer, coats the surface of the protective layer, and imparts lubricity to the lubricating layer to thereby reduce the frictional force of the head against the protective layer. R 3 and R 3’ representing a PFPE chain can be appropriately selected depending on the properties and the like required of the lubricant containing the fluorine-containing ether compound.

[0113] R 3 and one or two R 3’ may be partially the same or all the same, or each can be different. R 3 and one or two R 3’ are preferably all the same. This is because the coating state of the fluorine-containing ether compound to the protective layer becomes more uniform, and a lubricating layer having a better adhesion is formed.3 and 1 or 2 R 3’ The same also includes a case where the structures of the repeating units of the PFPE chain are the same and the average degree of polymerization is different.

[0114] R as 3 and R 3’ The PFPE chain represented by the formula (1) can be exemplified by a PFPE chain formed of a polymer or a copolymer of a perfluoroalkylene oxide, etc. As the perfluoroalkylene oxide, there can be exemplified, for example, a perfluoromethylenoxide, a perfluoroethylenoxide, a perfluoro-n-propylenoxide, a perfluoro-n-butylenoxide, etc.

[0115] R in the formula (1) 3 and 1 or 2 R 3’ For example, it is preferable that the PFPE chain represented by the following formula (4) be from a polymer or a copolymer of a perfluoroalkylene oxide.

[0116] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0117] (In the formula (4), w2, w3, w4, w5 represent the average degree of polymerization, each independently represents 0 to 20; wherein, a case where w2, w3, w4, w5 are all 0 at the same time is excluded; wl, w6 are the average values representing the number of CF2, each independently represents 1 to 3; the arrangement order of the repeating units in the formula (4) is not particularly limited.)

[0118] In the formula (4), w2, w3, w4, w5 represent the average degree of polymerization, each independently represents 0 to 20, preferably 0 to 15, more preferably 0 to 10. For example, w2, w3, w4, w5 each independently can be 1 to 18, 2 to 13, 3 to 8, 4 to 6, etc.

[0119] In the formula (4), wl, w6 are the average values representing the number of CF2, each independently represents 1 to 3. wl, w6 can be determined depending on the structure of the repeating unit disposed at the end of the chain structure in the PFPE chain represented by the formula (4), etc.

[0120] (CF2O), (CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) in the formula (4) are repeating units. The arrangement order of the repeating units in the formula (4) is not particularly limited. In addition, the number of kinds of the repeating units in the formula (4) is also not particularly limited.

[0121] Specifically, R 3 and R 3’ each independently is preferably any one of PFPE chains represented by the following formulae (4-1) to (4-4).

[0122] If R 3 and R 3’ each is any one of PFPE chains represented by the formulae (4-1) to (4-4), it becomes a fluorine-containing ether compound that can obtain a lubricating layer having good lubricity. In addition, in the case where R 3 and R 3’ each is any one of PFPE chains represented by the formulae (4-1) to (4-4), the proportion of the number of oxygen atoms (the number of ether bonds (-O-)) to the number of carbon atoms in the PFPE chain is appropriate. Thus, it becomes a fluorine-containing ether compound having moderate hardness. Thereby, the fluorine-containing ether compound coated on the protective layer is less likely to aggregate on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage. In addition, since the fluorine-containing ether compound has moderate softness, a lubricating layer having better chemical resistance and wear resistance can be formed.

[0123] -CF2-(OCF2CF2) h -(OCF2) i -OCF2- (4-1)

[0124] (In the formula (4-1), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0125] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2- (4-2)

[0126] (In the formula (4-2), j represents an average polymerization degree, and represents 1 to 15.)

[0127] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2- (4-3)

[0128] (In the formula (4-3), k represents an average polymerization degree, and represents 1 to 10.)

[0129] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 - (4-4)

[0130] (In formula (4-4), w8, w9 represent average polymerization degree, each independently represents 1 to 20; w7, w10 are average values representing the number of CF2, each independently represents 1 to 2.)

[0131] In formula (4-1), the arrangement order of the repeating units (OCF2CF2) and (OCF2) is not particularly limited. In formula (4-1), the number h of (OCF2CF2) and the number i of (OCF2) can be the same or different. The PFPE chain represented by formula (4-1) can be a polymer of (OCF2CF2). In addition, the PFPE chain represented by formula (4-1) can also be any one of a random copolymer, a block copolymer, an alternating copolymer formed of (OCF2CF2) and (OCF2).

[0132] In formulae (4-1) to (4-3), h representing average polymerization degree is 1 to 20, i is 0 to 20, j is 1 to 15, and k is 1 to 10, and thus a fluorine-containing ether compound that can provide a lubricating layer having good lubricity is obtained. In addition, in formulae (4-1) to (4-3), h, i representing average polymerization degree are 20 or less, j is 15 or less, and k is 10 or less, and thus the viscosity of the fluorine-containing ether compound does not excessively increase, and a lubricant containing the same is easily applied, and thus is preferred. In order to be a fluorine-containing ether compound that easily spreads and wets on a protective layer, and thus easily provides a lubricating layer having a uniform film thickness, h, i, j, k representing average polymerization degree are preferably 1 to 10, more preferably 1.5 to 8, and further preferably 2 to 7.

[0133] In formula (4-4), the arrangement order of the repeating units (CF2CF2CF2O) and (CF2CF2O) is not particularly limited. In formula (4-4), the number w8 of (CF2CF2CF2O) representing average polymerization degree and the number w9 of (CF2CF2O) can be the same or different. Formula (4-4) can contain any one of a random copolymer, a block copolymer, an alternating copolymer formed of the monomer units (CF2CF2CF2O) and (CF2CF2O).

[0134] In formula (4-4), w8 and w9 each independently representing average polymerization degree are each independently 1 to 20, preferably 1 to 15, and more preferably 1 to 10.

[0135] In formula (4-4), w7 and w10 are average values representing the number of CF2, each independently represents 1 to 2. w7 and w10 can be determined depending on the structure of the repeating unit disposed at the end of the chain structure in the PFPE chain represented by formula (4-4) or the like.

[0136] (R 2 and R 5 representing a divalent linking group having a polar group)

[0137] In the fluorinated ether compound represented by formula (1), R 2 and R 5 It is a divalent linker having one or more polar groups. R 2 In relation to R 1 The terminal side of the bond has an oxygen atom, which is bonded to R via an ether bond. 1 Bonding. R 5 In relation to R 6 The terminal side of the bond has an oxygen atom, which is bonded to R via an ether bond. 6 Bonding. In the fluorinated ether compound represented by formula (1), R 2 and R 5 Each component has one or more polar groups, thus, when a lubricating layer is formed on the protective layer using a lubricant containing these components, a suitable interaction occurs between the lubricating layer and the protective layer. 2 and R 5 The appropriate choice can be made based on the required properties of the lubricant containing fluorinated ether compounds.

[0138] R 2 With R 5 They can be the same or different. If R 2 With R 5 If the coating is the same, the fluorinated ether compound will result in a more uniform coating of the protective layer, forming a lubricating layer with better adhesion.

[0139] In this specification, the term "R" refers to... 2 With R 5 "Same" refers to the skeleton (-R) at the center of the fluorinated ether compound represented by formula (1). 3 [-CH2-R 4 -CH2-R 3’ ] n -) In terms of R 2 The atoms contained therein and R 5 The atoms contained therein are arranged in a symmetrical configuration.

[0140] As R 2 and R 5 Examples of polar groups include hydroxyl (-OH), amino (-NH2), carboxyl (-COOH), aldehyde (-COH), carbonyl (-CO-), and sulfonic acid (-SO3H). Among these, the hydroxyl group is particularly preferred. The interaction between the hydroxyl group and the protective layer, especially a protective layer formed from carbon-based materials, is significant. Therefore, if R... 2 and / or R 5If at least some of the polar groups are hydroxyl groups, the adhesion between the lubricating layer and the protective layer containing the fluorinated ether compound becomes higher. In this embodiment, R is more preferably preferred. 2 and R 5 All of its polar groups are hydroxyl groups.

[0141] R 2 and R 5 The number of polar groups each contains is preferably 1 to 3, more preferably 1 to 2. In R 2 and / or R 5 When the number of polar groups is 2 or more, the types of polar groups can be partially the same, all the same, or different.

[0142] In R 2 and / or R 5 When the polar group includes a hydroxyl group, R in formula (1) 2 The hydroxyl groups contained therein and R 5 The total number of hydroxyl groups contained therein is preferably 2 to 6, more preferably 2 to 4, and most preferably 2. If the total number of hydroxyl groups is 2 or more, R can be effectively obtained. 2 and / or R 5 The interaction between the hydroxyl groups and the protective layer results in a fluorinated ether compound that can form a lubricating layer with high adhesion to the protective layer. Furthermore, if the total number of the aforementioned hydroxyl groups is 6 or less, the number of polar groups that do not participate in the bonding of the active sites on the lubricating and protective layers decreases. Therefore, it is possible to prevent the polar groups that do not participate in the bonding of the active sites on the lubricating and protective layers from attracting environmental substances that generate pollutants, such as water, which causes corrosion of the magnetic recording medium, into the lubricating layer. This allows for the formation of a lubricating layer that more effectively inhibits contamination and corrosion of the magnetic recording medium. Additionally, if the total number of the aforementioned hydroxyl groups is 4 or less, the fluidity of the lubricating layer containing the fluorinated ether compound becomes sufficiently high. Therefore, even if a portion of the lubricating layer containing the fluorinated ether compound deforms due to wear, causing the fluorinated ether compound to migrate to other parts, its ability to return to its original position is high, resulting in superior wear resistance.

[0143] Preferred R 2 The divalent linker is represented in relation to R. 1 One end of the bond has an oxygen atom, and the other end (bonded to R) 2 Oxygen atoms are also disposed at the ends of adjacent CH2 atoms. Additionally, R is preferred. 5 The divalent linker is represented by R. 6 One end of the bond has an oxygen atom, and the other end (bonded to R) 5The end portion of the CH2adjacent to the oxygen atom is also provided with an oxygen atom. The oxygen atom provided at the end portion of the divalent linking group represented by R 2 and R 5 The oxygen atoms at both end portions of the divalent linking group represented by R 2 and R 5 form ether bonds (-O-) with the atoms bonded to both sides thereof. These ether bonds impart moderate flexibility to the fluorine-containing ether compound represented by formula (1), and increase the affinity of the polar group possessed by the divalent linking group represented by R 2 and R 5 to the protective layer.

[0144] R 2 and R 1 are preferably a group in which one or more polar groups are bonded to the carbon atoms of an alkylene group having 3 to 8 carbon atoms, and the end portions are oxygen atoms. The alkylene group can contain an ether bond between the carbon atoms. The alkylene group having 3 to 8 carbon atoms is preferably an alkylene group having 3 to 5 carbon atoms. The alkylene group having 3 to 8 carbon atoms preferably has a straight chain structure. This is because the fluorine-containing ether compound becomes more uniform in the coated state on the protective layer, and a lubricating layer having better adhesion can be formed.

[0145] R 2 in formula (1) is preferably a linking group represented by the following formula (2-1) or (2-2). In formula (2-1) and (2-2), the left-side oxygen atom is bonded to R 1 , and the right-side oxygen atom is bonded to CH2adjacent to R 2 .

[0146] If R 2 is a linking group represented by the following formula (2-1) or (2-2), R 2 and R 1 are bonded by an ether bond, and an ether bond is provided between R 2 and CH2adjacent to R 2 . As a result, a fluorine-containing ether compound having moderate flexibility is obtained, and a lubricating layer having better chemical resistance and wear resistance can be formed. In addition, if R 2 is formula (2-1), the fluorine-containing ether compound represented by formula (1) is easily synthesized, and is therefore preferred.

[0147]

[0148] (In formula (2-1), p1 represents an integer of 1 to 3.)

[0149] (In formula (2-2), q1 represents an integer of 2 to 4.)

[0150] The linking group represented by formula (2-2) has a structure in which 1 to 3 methylene groups are added to the skeleton of glycerol (-OCH2CH(OH)CH2O-). Therefore, the fluorine-containing ether compound represented by formula (1) has a structure in which the ether bonds are provided at both end portions of the divalent linking group represented by R2 The lubricating layer of the fluorine-containing ether compound of formula (2-2) becomes a lubricating layer having good hydrophobicity. As a result, water, which is a cause of corrosion of the magnetic recording medium, can be effectively prevented from intruding, and a lubricating layer having a high effect of suppressing corrosion of the magnetic recording medium is formed.

[0151] R 5 Preferably, the linking group is represented by the following formula (2-3) or (2-4). In formulae (2-3) and (2-4), the left-side oxygen atom is bonded to CH2adjacent to R 5 , and the right-side oxygen atom is bonded to R 6 .

[0152] If R 5 is a linking group represented by the following formula (2-3) or (2-4), R 5 is bonded via an ether bond to R 6 , and an ether bond is disposed between R 5 and CH2adjacent to R 5 . As a result, a fluorine-containing ether compound having moderate flexibility is obtained, and a lubricating layer having further improved chemical resistance and wear resistance is formed. In addition, if R 5 is formula (2-3), the fluorine-containing ether compound represented by formula (1) is easily synthesized, and is therefore preferred.

[0153]

[0154] (In formula (2-3), p2 represents an integer of 1 to 3.)

[0155] (In formula (2-4), q2 represents an integer of 2 to 4.)

[0156] The linking group represented by formula (2-4) has a structure in which 1 to 3 methylene groups are added to the backbone (-OCH2CH(OH)CH2O-) of glycerol. Therefore, R 5 The lubricating layer of the fluorine-containing ether compound of formula (2-4) becomes a lubricating layer having good hydrophobicity. As a result, water, which is a cause of corrosion of the magnetic recording medium, can be effectively prevented from intruding, and a lubricating layer having a high effect of suppressing corrosion of the magnetic recording medium is formed.

[0157] In formula (1), R 2 is a linking group represented by formula (2-1) or (2-2), and R 5is a linking group represented by formula (2-3) or (2-4). The linking group represented by formula (2-1) to (2-4) has a hydroxyl group, which is a particularly large polar group among arbitrary polar groups in terms of interaction with the protective layer. In addition, in the linking group represented by formula (2-1) to (2-4), a methylene group (-CH2-) is disposed on both sides of a carbon atom to which the hydroxyl group is bonded. Therefore, in the linking group represented by formula (2-1) to (2-4), the distance between the hydroxyl group and R 2 is a linking group represented by formula (2-1) or (2-2), and R 5 is a linking group represented by formula (2-3) or (2-4), becomes a fluorine-containing ether compound capable of forming a lubricating layer having higher adhesion to the protective layer for the following reasons.

[0158] That is, in the linking group represented by formula (2-1) to (2-4), a methylene group and R 1 or R 6 possessing an oxygen atom (-O-) are disposed between the carbon atom to which the hydroxyl group is bonded and R 2 or R 5 Therefore, the distance between the hydroxyl group contained in the linking group represented by formula (2-1) to (2-4) and the amide bond possessed by R 1 and / or R 6 becomes appropriate. In addition, the free rotation of the terminal group is slightly suppressed by the ether bond as the connecting portion of R 1 and R 2 , and / or R 5 and R 6 Therefore, the amide possessed by R 1 and / or R 6 and the hydroxyl group possessed by the linking group represented by formula (2-1) to (2-4) are less likely to interact with each other. Thus, the hydroxyl group possessed by the linking group represented by formula (2-1) to (2-4) and the terminal group represented by R 1 and / or R 6 each independently exhibit a good interaction with the protective layer and each independently easily bond to the functional group (active site) present in a large amount on the protective layer.

[0159] In the linking group represented by formula (2-1), p1 is an integer of 1 to 3. Since p1 in the linking group represented by formula (2-1) is 1 or more, in R 2In the case of the linking group represented by formula (2-1), a compound containing one or more hydroxyl groups having a particularly large interaction with the protective layer as a polar group is obtained. As a result, a fluorine-containing ether compound that provides a lubricating layer having a more excellent adhesion to the protective layer is obtained. In addition, in the case of the linking group represented by formula (2-1), since pi in formula (2-1) is 3 or less, it is possible to prevent a situation in which the number of hydroxyl groups in the linking group represented by formula (2-1) is large, thereby causing the polarity of the fluorine-containing ether compound to be excessively high, resulting in contamination or corrosion of a magnetic recording medium provided with a lubricating layer containing the same.

[0160] In addition, in the linking group represented by formula (2-1), in the case where pi in formula (2-1) is 2 or 3, the distance between the hydroxyl groups contained in the linking group represented by formula (2-1) becomes appropriate. As a result, even if the number of hydroxyl groups contained in R 2 is plural, each of the hydroxyl groups contained in R 2 is likely to participate in bonding to the active sites on the protective layer.

[0161] In the linking group represented by formula (2-1), pi is preferably 1 or 2. In the case where pi in the linking group represented by formula (2-1) is 1, a fluorine-containing ether compound that is easy to synthesize is obtained, and thus is more preferable.

[0162] In the linking group represented by formula (2-2), q1 is an integer of 2 to 4, preferably an integer of 2 to 3, and more preferably 2. If q1 in formula (2-2) is 2 to 4, the hydrophobicity of the fluorine-containing ether compound is increased by the methylene groups contained in formula (2-2), and a higher corrosion-inhibiting effect can be obtained.

[0163] In the linking group represented by formula (2-3), p2 is an integer of 1 to 3. Since p2 in the linking group represented by formula (2-3) is 1 or more, in the case where R 5 is the linking group represented by formula (2-3), a compound containing one or more hydroxyl groups having a particularly large interaction with the protective layer as a polar group is obtained. As a result, a fluorine-containing ether compound that provides a lubricating layer having a more excellent adhesion to the protective layer is obtained. In addition, in the case of the linking group represented by formula (2-3), since p2 in formula (2-3) is 3 or less, it is possible to prevent a situation in which the number of hydroxyl groups in the linking group represented by formula (2-3) is large, thereby causing the polarity of the fluorine-containing ether compound to be excessively high, resulting in contamination or corrosion of a magnetic recording medium provided with a lubricating layer containing the same.

[0164] In addition, in the linking group represented by formula (2-3), in the case where p2 in formula (2-3) is 2 or 3, the distance between the hydroxyl groups contained in the linking group represented by formula (2-3) becomes appropriate. As a result, even if the number of hydroxyl groups contained in R5 It contains multiple hydroxyl groups, R 5 The hydroxyl groups contained therein can also easily participate in the bonding with the active sites on the protective layer.

[0165] In the linking group represented by formula (2-3), p2 is preferably 1 or 2. When p2 is 1 in the linking group represented by formula (2-3), it becomes an easily synthesized fluorinated ether compound, and is therefore more preferred.

[0166] In the linking group represented by formula (2-4), q2 is an integer from 2 to 4, preferably an integer from 2 to 3, and more preferably 2. If q2 in formula (2-4) is 2 to 4, the hydrophobicity of the fluorinated ether compound can be improved by utilizing the methylene group contained in formula (2-4), thereby obtaining a higher corrosion inhibition effect.

[0167] In the fluorinated ether compounds represented by formula (1), in R 2 The linking group is represented by formula (2-1) or (2-2), and R 5 In the case where the linking group is represented by formula (2-3) or (2-4), R is more preferred. 2 With R 5 Same. Specifically, the preferred option is "R". 2 For equation (2-1), R 5 "For equation (2-3), and p1 in equation (2-1) is the same as p2 in equation (2-3)," or "R 2 For equation (2-2), R 5 It is equation (2-4), and q1 in equation (2-2) is the same as q2 in equation (2-4).

[0168] (R 1 and R 6 (representing the terminal group)

[0169] In the fluorinated ether compound represented by formula (1), R 1 and R 6 The terminal group is an organic group having 1 to 50 carbon atoms, and at least one of them is a group having a carbonyl carbon atom or nitrogen atom that forms an amide bond bonded to the carbon atom of an organic group having 1 to 8 carbon atoms (terminal group having an amide bond).

[0170] In the fluorinated ether compound represented by formula (1), the amide contained in the terminal group with amide bond exhibits a moderate interaction with the protective layer. Therefore, the terminal group with amide bond has the function of improving the adhesion between the lubricating layer and the protective layer and forming a lubricating layer with good chemical resistance and wear resistance.

[0171] In the fluorine-containing ether compound represented by formula (1), the kind of the terminal group having an amide bond can be appropriately selected depending on the properties and the like required of the lubricant containing the fluorine-containing ether compound.

[0172] The number of amide bonds possessed by the terminal group having an amide bond is not particularly limited, and can be one or more than two. In order to be a fluorine-containing ether compound that is relatively easy to produce, the number of amide bonds possessed by the terminal group having an amide bond is preferably one.

[0173] The terminal group having an amide bond is a group bonded to a carbon atom of an organic group having 1 to 8 carbon atoms, the carbon atom constituting a carbonyl carbon atom or a nitrogen atom of an amide bond. In the fluorine-containing ether compound represented by formula (1), since the number of carbon atoms of the above-described organic group is 1 to 8, the terminal group having an amide bond does not form steric hindrance, and becomes a fluorine-containing ether compound in which the affinity of the amide to the protective layer is good.

[0174] As the organic group in the terminal group having an amide bond, a phenyl group or an alkyl group having a linear or branched structure having 1 to 8 carbon atoms, and the like can be given, and is preferably a phenyl group or an alkyl group having 1 to 6 carbon atoms. If the organic group in the terminal group having an amide bond is a phenyl group or an alkyl group having 1 to 6 carbon atoms, the interaction between the amide possessed by R 1 and / or R 6 and the polar group possessed by the adjacent linking group (R 2 or R 5 ) can be more effectively suppressed, and a fluorine-containing ether compound in which the affinity of the amide to the protective layer is large is obtained.

[0175] As the group bonded to a carbon atom of an organic group having 1 to 8 carbon atoms, specifically, a group represented by formula (5-1) or (5-2) shown below can be given.

[0176] The dotted line in formula (5-1) and (5-2) is a bond to the organic group in R 1 or R 6 . In the case where the terminal group having an amide bond has a group represented by formula (5-1), the terminal group having an amide bond becomes a group having a carbonyl carbon atom constituting an amide bond bonded to a carbon atom of the organic group in R 1 or R 6 . In the case where the terminal group having an amide bond has a group represented by formula (5-2), the terminal group having an amide bond becomes a group having a nitrogen atom constituting an amide bond bonded to a carbon atom of the organic group in R 1 or R 6 .

[0177]

[0178] (incidentally, in formulae (5-1) and (5-2), X 1 , X 2 , X 3 , X 4 each independently is any group selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, an octafluoropentyl group, a tridecafluorooctyl group, a phenyl group, a methoxyphenyl group, a fluorophenyl group, a naphthyl group, a phenethyl group, a methoxyphenethyl group, a fluorophenethyl group, a benzyl group, a methoxybenzyl group, a naphthylmethyl group, a methoxynaphthyl group, a pyrrolyl group, a pyrazolyl group, a methylpyrazolylmethyl group, an imidazolyl group, a furanyl group, a furfuryl group, a thiazolyl group, an isothiazolyl group, a thiophenyl group, a thiophenylethyl group, a thiazolyl group, a methylthiazolyl ethyl group, an isothiazolyl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a benzimidazolyl group, a benzothiazolyl group, a benzisothiazolyl group, a quinolyl group, an isoquinolyl group, a quinazolyl group, a quinoxalyl group, a phtalazinyl group, a cinnolyl group, a vinyl group, an allyl group, a butenyl group, a propynyl group, a propargyl group, a butynyl group, a methylbutynyl group, a pentynyl group, a methylpentynyl group, a hexynyl group, a cyanoethyl group.

[0179] in formula (5-1), X 1 , X 2 each independently is preferably a group selected from a hydrogen atom, a methyl group, an ethyl group, a phenyl group, a methoxyphenyl group, a trifluoromethyl group, an allyl group.

[0180] in formula (5-2), X 3 is preferably a group selected from a methyl group, an ethyl group, a phenyl group, a methoxyphenyl group, a naphthyl group, a trifluoromethyl group, an allyl group. X 4 is preferably a group selected from a hydrogen atom, a methyl group, an ethyl group, a phenyl group, a methoxyphenyl group, a trifluoromethyl group, an allyl group.

[0181] X in formula (5-1) 1 and X 2 may be bonded to each other to form a cyclic structure. In this case, X in formula (5-1) 1 -X 2 may be, for example, a structure composed of a combination of 1 or more groups selected from a methylene group (-CH2-), an ether bond (-0-), an amine structure (-NH-). X in formula (5-1) 1 and X 2 bonded to each other to form a cyclic structure are preferably a 5- to 7-membered ring containing a nitrogen atom constituting an amide bond.

[0182] In addition, X in formula (5-2)​​​3 X and X 4 may be bonded to each other to form a cyclic structure. In this case, X 3 -X 4 may be, for example, a structure composed of a combination of 1 or more kinds of groups selected from methylene (-CH2-), ether bond (-0-), and amine structure (-NH-). X 3 X and X 4 bonded to each other to form a cyclic structure is preferably a 5- to 7-membered ring containing a carbonyl carbon atom and a nitrogen atom constituting an amide bond.

[0183] As the terminal group having an amide bond, any of the organic groups represented by the following formulae (6-1) to (6-12) can be given, for example. The dotted line in formulae (6-1) to (6-12) is a connecting bond to R 2 or R 5 in formula (1).

[0184] The terminal group having an amide bond in the fluorine-containing ether compound of the present embodiment is not limited to the organic groups represented by formulae (6-1) to (6-12).

[0185]

[0186] (In formula (6-1), t represents an integer of 0 to 7.)

[0187] (In formula (6-2), u represents an integer of 0 to 7.)

[0188] Among the terminal groups represented by formulae (6-1) to (6-12), as the terminal group having an amide bond, the terminal groups represented by formulae (6-1) to (6-4) are preferably used. This is because they become fluorine-containing ether compounds that are relatively easy to produce.

[0189] The terminal group represented by formula (6-1) or (6-2) has a straight-chain aliphatic amide, and has higher flowability than the terminal groups represented by formulae (6-3) to (6-12). Therefore, even if a part of the lubricating layer containing the fluorine-containing ether compound is deformed due to abrasion, and the fluorine-containing ether compound in the lubricating layer moves to another site, the repairability of returning to the original position is high. As a result, the fluorine-containing ether compound having the terminal group represented by formula (6-1) or (6-2) can form a lubricating layer having more excellent abrasion resistance.

[0190] In formula (6-1), t is an integer of 0 to 7, and is preferably an integer of 0 to 5. This is because the amide possessed by R 1 and / or R 6 can be more effectively inhibited from reacting with the adjacent linking group (R 2 or R 5the polar groups possessed by R

[0191] In formula (6-2), u is an integer of 0 to 7, and preferably an integer of 0 to 5. This is because R 1 and / or R 6 the polar groups possessed by R 2 and R 5 .

[0192] In addition, the terminal group represented by formula (6-3) or (6-4) has a comparatively rigid aromatic amide, and thus the movement of the molecule is somewhat restricted. Therefore, the fluorine-containing ether compound having the terminal group represented by formula (6-3) or (6-4) has a lower ability to hinder the interaction between the amide possessed by R 1 and R 6 and the polar groups possessed by R 2 and R 5 and the protective layer from each other than the fluorine-containing ether compound having the terminal group represented by formula (6-1) or (6-2).

[0193] Further, the aromatic amide possessed by the terminal group represented by formula (6-3) or (6-4) has a planar structure composed of carbon, oxygen and nitrogen having sp 2 hybrid orbitals in a wide range from the aromatic ring to the amide skeleton. Therefore, it is presumed that the interaction between the aromatic amide possessed by the terminal group represented by formula (6-3) or (6-4) and the protective layer is stronger than the interaction between the aliphatic amide possessed by the terminal group represented by formula (6-1) or (6-2) and the protective layer.

[0194] In addition, the aromatic amide possessed by the terminal group represented by formula (6-3) or (6-4) contains a phenyl group as the organic group in the terminal group. Therefore, the hydrophobicity of the lubricating layer containing the fluorine-containing ether compound becomes good, and the invasion of water, which is a cause of corrosion of the magnetic recording medium, can be effectively hindered.

[0195] Thus, the fluorine-containing ether compound having the terminal group represented by formula (6-3) or (6-4) can form a lubricating layer having more excellent chemical resistance and a higher effect of suppressing corrosion of the magnetic recording medium.

[0196] In the terminal group having an amide bond represented by formula (6-3), the carbonyl carbon atom constituting the amide bond can be bonded at any of the ortho position, the meta position and the para position of the phenyl group as the organic group. In order to more effectively suppress the interaction between the amide possessed by R 1 and / or R 6 and the adjacent linking group (R 2 or R5 The interaction between the polar groups of the phenyl group is preferably such that a carbonyl carbon atom constituting an amide bond is bonded at the para position of the phenyl group.

[0197] In the terminal group with an amide bond represented by formula (6-4), a nitrogen atom constituting the amide bond can be bonded at any position (ortho, meta, or para) of the phenyl group, which is an organic group. To more effectively suppress R... 1 and / or R 6 The amide group it contains and the adjacent linking group (R) 2 or R 5 The interaction between the polar groups of the phenyl group is preferably such that a nitrogen atom constituting an amide bond is bonded at the para position of the phenyl group.

[0198] In the fluorinated ether compound represented by formula (1), R 1 and R 6 When both of the terminal groups represented are terminal groups with amide bonds, R 1 With R 6 They can be the same or different. If R 1 With R 6 If the coating is the same, the fluorinated ether compound will result in a more uniform coating of the protective layer, forming a lubricating layer with better adhesion.

[0199] In this specification, the term "R" refers to... 1 With R 6 "Same" refers to the skeleton (-R) at the center of the fluorinated ether compound represented by formula (1). 3 [-CH2-R 4 -CH2-R 3’ ] n -) In other words, separated by methylene and R 2 or R 5 R 1 The atoms contained therein and R 6 The atoms contained therein are arranged in a symmetrical configuration.

[0200] Among the fluorinated ether compounds represented by formula (1), only R 1 and R 6 One of the terminal groups represented (e.g., R) 1 In the case where the terminal group is an amide bond, another terminal group that is not an amide bond (e.g., R) 6 Any organic group having 1 to 50 carbon atoms is acceptable; it can be any group and there are no particular limitations. The other terminal group is preferably an organic group having 1 to 30 carbon atoms, and more preferably an organic group having 1 to 15 carbon atoms.

[0201] The other terminal group is preferably an organic group having at least one double bond or triple bond, and examples thereof include a group containing an aromatic ring, a group containing an unsaturated heterocyclic ring, a group containing an alkenyl group, a group containing an alkynyl group, and the like. The organic group having at least one double bond or triple bond can also be a group containing a cyano group, for example. That is, the double bond and the triple bond can be a carbon-carbon bond, or a bond formed between a carbon atom and a heteroatom (e.g., a carbon-nitrogen bond).

[0202] The other terminal group can also be an alkyl group having 1 to 8 carbon atoms which can have a substituent. As the substituent, an alkoxy group, a hydroxyl group, a mercapto group, a carboxyl group, a carbonyl group, an amino group, a fluorine group, and the like can be given. The alkyl group is more preferably an alkyl group having 1 to 6 carbon atoms, and further preferably an alkyl group having 1 to 4 carbon atoms. Among the alkyl groups having 1 to 8 carbon atoms which can have a substituent, an alkyl group having 1 to 8 carbon atoms which has a hydroxyl group is preferable.

[0203] In the case where the other terminal group is an organic group having at least one double bond or triple bond, specific examples thereof include a phenyl group, a methoxyphenyl group, a fluorophenyl group, a naphthyl group, a phenethyl group, a methoxyphenethyl group, a fluorophenethyl group, a benzyl group, a methoxybenzyl group, a naphthylmethyl group, a methoxynaphthyl group, a pyrrolyl group, a pyrazolyl group, a methylpyrazolylmethyl group, an imidazolyl group, a furanyl group, a furfuryl group, a thiazolyl group, an isothiazolyl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a benzimidazolyl group, a benzothiazolyl group, a benzopyrazolyl group, a benzisothiazolyl group, a quinolyl group, an isoquinolyl group, a quinazolyl group, a quinoxalyl group, a phtalazinyl group, a cinnolinyl group, a vinyl group, an allyl group, a butenyl group, a propynyl group, a propargyl group, a butynyl group, a methylbutynyl group, a pentynyl group, a methylpentynyl group, a hexynyl group, a cyanoethyl group, and the like. a thiazolyl group, an isothiazolyl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a benzimidazolyl group, a benzothiazolyl group, a benzopyrazolyl group, a benzisothiazolyl group, a quinolyl group, an isoquinolyl group, a quinazolyl group, a quinoxalyl group, a phtalazinyl group, a cinnolinyl group, a vinyl group, an allyl group, a butenyl group, a propynyl group, a propargyl group, a butynyl group, a methylbutynyl group, a pentynyl group, a methylpentynyl group, a hexynyl group, a cyanoethyl group, and the like. a thiazolyl group, an isothiazolyl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a benzimidazolyl group, a benzothiazolyl group, a benzopyrazolyl group, a benzisothiazolyl group, a quinolyl group, an isoquinolyl group, a quinazolyl group, a quinoxalyl group, a phtalazinyl group, a cinnolinyl group, a vinyl group, an allyl group, a butenyl group, a propynyl group, a propargyl group, a butynyl group, a methylbutynyl group, a pentynyl group, a methylpentynyl group, a hexynyl group, a cyanoethyl group, and the like. a thiazolyl group, an isothiazolyl group, a pyridyl group, a pyrimidinyl group, a pyridazinyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a benzimidazolyl group, a benzothiazolyl group, a benzopyrazolyl group, a benzisothiazolyl group, a quinolyl group, an isoquinolyl group, a quinazolyl group, a quinoxalyl group, a phtalazinyl group, a cinnolinyl group, a vinyl group, an allyl group, a butenyl group, a propynyl group, a propargyl group, a butynyl group, a methylbutynyl group, a pentynyl group, a methylpentynyl group, a hexynyl group, a cyanoethyl group, and the like.

[0204] In the case where the other terminal group is an alkyl group having 1 to 8 carbon atoms which can have a substituent, specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, an octafluoropentyl group, a tridecafluorooctyl group, a hydroxymethyl group (-CH2OH), a hydroxyethyl group (-CH2CH2OH), a hydroxypropyl group (-CH2CH2CH2OH), a hydroxybutyl group (-CH2CH2CH2CH2OH), and the like.

[0205] Among the above-mentioned groups, the above-mentioned another end group is preferably any one of a phenyl group, a methoxyphenyl group, a thienylethyl group, a naphthyl group, a butenyl group, an allyl group, an acetylenyl group, a phenethyl group, a methoxyphenyl ethyl group, a fluorophenethyl group, a hydroxyethyl group, a hydroxypropyl group, particularly preferably any one of a phenyl group, a naphthyl group, a thienylethyl group, an allyl group, a butenyl group, a hydroxyethyl group. In this case, a fluorine-containing ether compound capable of forming a lubricating layer having more excellent wear resistance is obtained.

[0206] In the fluorine-containing ether compound represented by formula (1), R 3 and 1 or 2 R 3’ are all the same, and R 1 - R 2 - and R 6 - R 5 - are the same. This is because it becomes a fluorine-containing ether compound that can be easily and efficiently manufactured. Furthermore, in the case of a fluorine-containing ether compound in which R 4 is a linking group represented by formula (3-1), it can be more easily and efficiently manufactured, and thus is more preferable.

[0207] Specifically, the fluorine-containing ether compound represented by formula (1) is preferably any one of the compounds represented by the following formulas (A) to (Y).

[0208] In the case where the compound represented by formula (1) is any one of the compounds represented by the following formulas (A) to (Y), raw materials are easily available, and a lubricating layer having excellent adhesion, chemical resistance, and wear resistance even with a thin thickness, and a high effect of suppressing corrosion of a magnetic recording medium can be formed.

[0209] The compounds represented by the following formulas (A) to (Y) are all the same in the PFPE chain represented by R 3 and 1 or 2 R 3’ in formula (1). Among the compounds represented by the following formulas (A) to (Y), Rf1, Rf2, and Rf3 representing the PFPE chain are the following structures, respectively. That is, in the compounds represented by the following formulas (A) to (M), (P) to (X), Rf1 is the PFPE chain represented by the above formula (4-1). In the compounds represented by the following formulas (N), (Y), Rf2 is the PFPE chain represented by the above formula (4-2). In the compound represented by the following formula (O), Rf3 is the PFPE chain represented by the above formula (4-3). Note that h and i in Rf1, j in Rf2, and k in Rf3 representing the PFPE chain in formulas (A) to (Y) are values representing average polymerization degree, and thus are not necessarily limited to integers.

[0210]

[0211] The compounds represented by the following formulas (A) to (Y) are all R 2 is a linking group represented by the above formula (2-1) or (2-2), and R 5 is a linking group represented by the above formula (2-3) or (2-4).

[0212] The compounds represented by the following formulas (A) to (Y) are all R 4 is a linking group represented by the above formula (3-1) to (3-3).

[0213] The compounds represented by the following formulas (A) to (Y) are all R 1 and / or R 6 is a group represented by formula (5-1) or (5-2).

[0214] In the compound represented by the following formula (A), n in formula (1) is 1. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R 2 is a linking group represented by the above formula (2-1) and p1 is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. R 4 is a linking group represented by the above formula (3-1). R 3 and R 3’ is a PFPE chain represented by the above formula (4-1).

[0215] In the compounds represented by the following formulas (B) to (D), n in formula (1) is all 1. R 2 is a linking group represented by the above formula (2-1) and p1 is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. R 4 is a linking group represented by the above formula (3-1). R 3 and R 3’ is a PFPE chain represented by the above formula (4-1).

[0216] In the compound represented by the following formula (B), R 1 and R 6 is a terminal group represented by the above formula (6-2) and u is 1. In the compound represented by the following formula (C), R 1 and R 6 is a terminal group represented by the above formula (6-2) and u is 3. In the compound represented by the following formula (D), R 1 and R 6 is a terminal group represented by the above formula (6-2) and u is 5.

[0217] The compound represented by the following formula (E) is one in which n in formula (1) is 1. R 1 and R 6 is a terminal group represented by the above formula (6-3) and has a carbonyl carbon atom that constitutes an amide bond bonded at the para position of the phenyl group. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. R 4 is a linking group represented by the above formula (3-1). R 3 and R 3’ is a PFPE chain represented by the above formula (4-1).

[0218] The compound represented by the following formula (F) is one in which n in formula (1) is 1. R 1 and R 6 is a terminal group represented by the above formula (6-4) and has a nitrogen atom that constitutes an amide bond bonded at the para position of the phenyl group. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. R 4 is a linking group represented by the above formula (3-1). R 3 and R 3’ is a PFPE chain represented by the above formula (4-1).

[0219] The compound represented by the following formula (G) is one in which n in formula (1) is 1. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R 2 is a linking group represented by the above formula (2-1) and pi is 2. R 5 is a linking group represented by the above formula (2-3) and p2 is 2. R 4 is a linking group represented by the above formula (3-1). R 3 and R 3’ is a PFPE chain represented by the above formula (4-1).

[0220] The compound represented by the following formula (H) is one in which n in formula (1) is 1. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 2. R 4 is a linking group represented by the above formula (3-1). R 3 and R 3’a PFPE chain represented by the above formula (4-1).

[0221] The compound represented by the following formula (I) is one in which n in formula (1) is 1. 1 and R 6 a terminal group represented by the above formula (6-1) and t is 1. 2 a linking group represented by the above formula (2-2) and q1 is 2. 5 a linking group represented by the above formula (2-4) and q2 is 2. 4 a linking group represented by the above formula (3-1). 3 and R 3’ a PFPE chain represented by the above formula (4-1).

[0222] The compound represented by the following formula (I) is one in which n in formula (1) is 1. 1 and R 6 a terminal group represented by the above formula (6-1) and t is 1. 2 a linking group represented by the above formula (2-1) and p1 is 1. 5 a linking group represented by the above formula (2-3) and p2 is 1. 4 a linking group represented by the above formula (3-3) and s is 2. 3 and R 3’ a PFPE chain represented by the above formula (4-1).

[0223] The compound represented by the following formula (I) is one in which n in formula (1) is 1. 1 a terminal group represented by the above formula (6-1) and t is 1. 6 is a hydroxyethyl group (-CH2CH2OH) as a terminal group having no amide bond. 2 a linking group represented by the above formula (2-1) and p1 is 1. 5 a linking group represented by the above formula (2-3) and p2 is 1. 4 a linking group represented by the above formula (3-1). 3 and R 3’ a PFPE chain represented by the above formula (4-1).

[0224] The compound represented by the following formula (I) is one in which n in formula (1) is 1. 1 a terminal group represented by the above formula (6-1) and t is 1. 6 is an allyl group as a terminal group having no amide bond. 2 a linking group represented by the above formula (2-1) and p1 is 1. 5R is the linking group represented by the above formula (2-3) and p2 is 2. 4 R represents the linking group indicated by formula (3-1) above. 3 and R 3’ Let be the PFPE chain represented by equation (4-1) above.

[0225] In the compounds represented by the following formula (M), n in formula (1) is 1. R 1 R represents the terminal group as shown in equation (6-1) above, and t is 1. 6 It is a phenyl group that does not have an amide bond as a terminal group. R 2 R is the linking group represented by the above formula (2-1) and p1 is 1. 5 R is the linking group represented by the above formula (2-3) and p2 is 1. 4 R represents the linking group indicated by formula (3-1) above. 3 and R 3’ Let be the PFPE chain represented by equation (4-1) above.

[0226] In the compounds represented by the following formulas (N) and (O), n in formula (1) is always 1. 1 and R 6 R represents the terminal group as shown in equation (6-1) above, and t is 1. 2 R is the linking group represented by the above formula (2-1) and p1 is 1. 5 R is the linking group represented by the above formula (2-3) and p2 is 1. 4 The linking group is represented by the above formula (3-1).

[0227] In the compounds represented by the following formula (N), R 3 and R 3’ The PFPE chain is represented by formula (4-2) above. In the compounds represented by formula (O) below, R... 3 and R 3’ Let be the PFPE chain represented by equation (4-3) above.

[0228] In the compounds represented by the following formula (P), n in formula (1) is 2. R 1 and R 6 R represents the terminal group as shown in equation (6-1) above, and t is 1. 2 R is the linking group represented by the above formula (2-1) and p1 is 1. 5 The linking group is represented by the above formula (2-3), and p2 is 1.2 R. 4 R represents the linking group indicated by formula (3-1) above. 3 and 2 Rs 3’ Let be the PFPE chain represented by equation (4-1) above.

[0229] The compounds represented by the following formulae (Q) and (R) are such that n in formula (1) is 2. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0230] The compounds represented by the following formula (Q) are such that R 1 and R 6 is a terminal group represented by the above formula (6-2) and u is 1. The compounds represented by the following formula (R) are such that R 1 and R 6 is a terminal group represented by the above formula (6-2) and u is 3.

[0231] The compounds represented by the following formula (S) are such that n in formula (1) is 2. R 1 and R 6 is a terminal group represented by the above formula (6-3) and the carbonyl carbon atom constituting the amide bond is bonded at the para position of the phenyl group. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0232] The compounds represented by the following formula (T) are such that n in formula (1) is 2. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. 2 R 4 is a linking group represented by the above formula (3-2) and a linking group represented by the above formula (3-3). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0233] The compounds represented by the following formula (U) are such that n in formula (1) is 2. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R2 is a linking group represented by the above formula (2-1) and pi is 2. R 5 is a linking group represented by the above formula (2-3) and p2 is 2. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0234] is a compound represented by the following formula (V) in which n in formula (1) is 2. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R 2 is a linking group represented by the above formula (2-2) and qi is 2. R 5 is a linking group represented by the above formula (2-4) and q2 is 2. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0235] is a compound represented by the following formula (W) in which n in formula (1) is 2. R 1 is a terminal group represented by the above formula (6-1) and t is 1. R 6 is a hydroxyethyl group (-CH2CH2OH) as a terminal group not having an amide bond. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0236] is a compound represented by the following formula (X) in which n in formula (1) is 2. R 1 is a terminal group represented by the above formula (6-1) and t is 1. R 6 is an allyl group as a terminal group not having an amide bond. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 2. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-1).

[0237] The compound represented by the following formula (Y) is one in which n in formula (1) is 2. R 1 and R 6 is a terminal group represented by the above formula (6-1) and t is 1. R 2 is a linking group represented by the above formula (2-1) and pi is 1. R 5 is a linking group represented by the above formula (2-3) and p2 is 1. 2 R 4 is a linking group represented by the above formula (3-1). R 3 and 2 R 3’ is a PFPE chain represented by the above formula (4-2).

[0238]

[0239] (In 2 Rf1in formula (A), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0240] (In 2 Rf1in formula (B), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0241] (In 2 Rf1in formula (C), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0242]

[0243] (In 2 Rf1in formula (D), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0244] (In 2 Rf1in formula (E), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0245] (In 2 Rf1in formula (F), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0246]

[0247] (In 2 Rf1in formula (G), h, i represent average polymerization degree, h represents 1 to 20, and i represents 0 to 20. The average polymerization degree can be the same or different between the 2 Rf1.)

[0248] (2 Rf1in the formula (H), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be the same or different between 2 Rf1.)

[0249] (2 Rf1in the formula (I), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be the same or different between 2 Rf1.)

[0250]

[0251] (2 Rf1in the formula (J), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be the same or different between 2 Rf1.)

[0252] (2 Rf1in the formula (K), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be the same or different between 2 Rf1.)

[0253] (2 Rf1in the formula (L), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be the same or different between 2 Rf1.)

[0254]

[0255] (2 Rf1in the formula (M), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be the same or different between 2 Rf1.)

[0256] (2 Rf2in the formula (N), j represents average polymerization degree, and represents 1 to 15; the average polymerization degree can be the same or different between 2 Rf2.)

[0257] (2 Rf3in the formula (O), k represents average polymerization degree, and represents 1 to 10; the average polymerization degree can be the same or different between 2 Rf3.)

[0258]

[0259] (3 Rf1in the formula (P), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree can be different between 3 Rf1, or the average polymerization degree of 2 or 3 Rf1can be the same.)

[0260] (3 Rf1in the formula (Q), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0261] (3 Rf1in the formula (R), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0262]

[0263] (3 Rf1in the formula (S), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0264] (3 Rf1in the formula (T), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0265] (3 Rf1in the formula (U), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0266]

[0267] (3 Rf1in the formula (V), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0268] (3 Rf1in the formula (W), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0269]

[0270] (3 Rf1in the formula (X), h, i represent average polymerization degree, h represents 1 to 20, i represents 0 to 20; the average polymerization degree of 3 Rf1may be different, or the average polymerization degrees of 2 or 3 Rf1are the same.)

[0271] (3 Rf2in formula (Y), j represents the average degree of polymerization, and represents 1 to 15; the average degree of polymerization can be different for each of the 3 Rf2, or the average degree of polymerization can be the same for 2 or 3 Rf2.)

[0272] The number average molecular weight (Mn) of the fluorine-containing ether compound of the present embodiment is preferably in the range of 500 to 10,000, and particularly preferably in the range of 1,000 to 5,000. If the number average molecular weight is 500 or greater, the lubricating layer made of the lubricant containing the fluorine-containing ether compound of the present embodiment has excellent heat resistance. The number average molecular weight of the fluorine-containing ether compound is more preferably 1,000 or greater. In addition, if the number average molecular weight is 10,000 or less, the viscosity of the fluorine-containing ether compound becomes appropriate, and by applying the lubricant containing the same, a lubricating layer having a relatively thin film thickness can be easily formed. In order to become a viscosity that is easy to handle in the case of being applied to a lubricant, the number average molecular weight of the fluorine-containing ether compound is preferably 5,000 or less.

[0273] The number average molecular weight (Mn) of the fluorine-containing ether compound is measured by using AVANCE III 400 manufactured by Bruker Biospin, Inc. 1 H-NMR and 19 F-NMR. Specifically, the number of repeating units of the PFPE chain is calculated from the integral value measured by 19 F-NMR, and the number average molecular weight is calculated. In the measurement of NMR (nuclear magnetic resonance), the sample is diluted in a hexafluorobenzene / d-acetone (4 / 1 v / v) solvent and then measured. 19 The reference of the chemical shift of F-NMR is set to the peak of hexafluorobenzene at -164.7 ppm, 1 The reference of the chemical shift of H-NMR is set to the peak of acetone at 2.2 ppm.

[0274] For the fluorine-containing ether compound of the present embodiment, it is preferable to perform molecular weight fractionation using an appropriate method so that the molecular weight dispersity (ratio of weight average molecular weight (Mw) / number average molecular weight (Mn)) is 1.3 or less.

[0275] In the present embodiment, as the method of performing molecular weight fractionation, there is no particular limitation, and molecular weight fractionation using silica gel column chromatography, gel permeation chromatography (GPC), or the like, molecular weight fractionation using supercritical extraction, or the like can be employed.

[0276] "Manufacturing method"

[0277] The manufacturing method of the fluorine-containing ether compound of the present embodiment is not particularly limited, and a conventionally known manufacturing method can be employed. The fluorine-containing ether compound of the present embodiment can be manufactured, for example, using the manufacturing method shown below.

[0278] (1st manufacturing method)

[0279] In the case of a compound in which n is 1, R 3 and R 3’ in formula (1) are the same and R 1 - R 2 - is the same as R 6 - R 5 , the following production method shown below can be employed.

[0280] First, a fluorine-based compound in which a hydroxymethyl group (-CH2OH) is provided at each of both ends of a perfluoropolyether chain corresponding to R 3 and R 3’ in formula (1) is prepared.

[0281] Next, the hydroxyl group of the hydroxymethyl group provided at one end of the fluorine-based compound is allowed to react with the epoxy group of an epoxy compound having a group (= a group that becomes R 1 - R 2 (= a group that becomes R 6 - R 5 ). Thus, a first intermediate compound having a group corresponding to R 3 (= R 3’ ) at one end of a perfluoropolyether chain corresponding to R 1 - R 2 (= R 6 - R 5 ) is obtained.

[0282] As the epoxy compound having a group (= a group that becomes R 1 - R 2 (= a group that becomes R 6 - R 5 ), for example, a compound represented by formulae (7-1a) to (7-1c), (7-2a) to (7-2c), (7-3), and (7-4) shown below, and the like can be used.

[0283] In the case of synthesizing the above first intermediate compound by allowing the above fluorine-based compound to react with the above epoxy compound, the hydroxyl group possessed by the above epoxy compound can be protected using an appropriate protecting group and then allowed to react with the above fluorine-based compound.

[0284]

[0285] As the epoxy compound having a group (= a group that becomes R 1 - R 2 (= a group that becomes R 6 - R 5 ), for example, in the case where R2 is a linking group represented by the above formula (2-1) and pi is 1 (=R 5 is a linking group represented by the above formula (2-3) and p2 is 1), it can be produced by the method shown below. That is, as shown in the following formula (8), it can be produced by a method of reacting an alcohol having a structure of a terminal group represented by R 1 or R 6 in formula (1) (R in formula (8) ) with a halogen compound having an epoxy group corresponding to R 2 or R 5 .

[0286]

[0287] (in formula (8), R represents a structure of a terminal group represented by R 1 or R 6 in formula (1).)

[0288] In addition, for the above epoxy compound, for example, in a case where R 2 is a linking group represented by the above formula (2-1) and pi is 2 (=R 5 is a linking group represented by the above formula (2-3) and p2 is 2), it can be produced by the method shown below. That is, as shown in the following formula (9), it can be produced by a method of subjecting an alcohol having a structure of a terminal group represented by R 1 or R 6 in formula (1) (R in formula (9) ) to an addition reaction with allyl glycidyl ether. Then, the compound obtained by the addition reaction is subjected to action with m-chloroperoxybenzoic acid (mCPBA) to perform oxidation.

[0289]

[0290] (in formula (9), R represents a structure of a terminal group represented by R 1 or R 6 in formula (1).)

[0291] In addition, for the above epoxy compound, for example, in a case where R 2 is a linking group represented by the above formula (2-2) and qi is 2 (=R 5 is a linking group represented by the above formula (2-4) and q2 is 2), it can be produced by the method shown below. That is, as shown in the following formula (10), it can be produced by a method of subjecting an alcohol having a structure of a terminal group represented by R 1 or R 6An alcohol with the structure of the terminal group (R in formula (10)) and having a terminal group corresponding to R 2 Or R 5 The alkenyl halogen compound is reacted. Then, the resulting compound is reacted with m-chloroperoxybenzoic acid (mCPBA) to undergo oxidation.

[0292]

[0293] (In equation (10), R represents the R in equation (1). 1 Or R 6 (The structure of the terminal group is shown.)

[0294] The aforementioned epoxy compounds can be purchased commercially available for use.

[0295] Next, make in the corresponding R 3 (=R 3’ One end of the perfluoropolyether chain has a corresponding R 1 -R 2 - group (=corresponding to R) 6 -R 5 The first intermediate compound of the group (-), and having a corresponding R 4 The reaction is carried out with halogen compounds with epoxy groups or dihalogen compounds with protected hydroxyl groups.

[0296] In the first manufacturing method, the following steps may be performed instead of the steps described above.

[0297] That is, it can also be manufactured by the following method: making the material corresponding to R... 3 (=R 3’ One end of the perfluoropolyether chain has a corresponding R 1 -R 2 - group (=corresponding to R) 6 -R 5 The first intermediate compound of the group (-), and having a corresponding R 4 The first intermediate compound is reacted with an alkenyl halogen compound to produce a second intermediate compound. The resulting second intermediate compound is then oxidized to produce an epoxide compound, thereby reacting the first intermediate compound described above.

[0298] By performing the above steps, we can obtain n=1 and R in equation (1). 3 and R 3’ The two PFPE chains are identical and R 1 -R 2 -with R 6 -R 5 - The same compound.

[0299] (Second Manufacturing Method)

[0300] In manufacturing formula (1), n ​​is 1 and R 1 With R 6 R 2 With R 5 R 3 With R 3’ When there are more than one different compound in the two PFPE chains, the manufacturing method shown below can be used.

[0301] In this case, the process is the same as in the first manufacturing method, manufacturing in the area corresponding to R. 3 One end of the perfluoropolyether chain has a corresponding R 1 -R 2 The first intermediate compound of the - group.

[0302] Next, make in the corresponding R 3 One end of the perfluoropolyether chain has a corresponding R 1 -R 2 The first intermediate compound with a group corresponding to R, and the compound having a group corresponding to R 4 The halogen compound with an epoxy group or a dihalogen compound having a protected hydroxyl group is reacted. Thus, a compound corresponding to R is produced. 3 One end of the perfluoropolyether chain has a corresponding R 1 -R 2 - a group, and at another end having a corresponding R 4 A third intermediate compound containing epoxy or halogen groups.

[0303] Next, following the same procedure as with the first intermediate compound, the product is manufactured in the form corresponding to R. 3’ One end of the perfluoropolyether chain has a corresponding R 6 -R 5 The fourth intermediate compound of the - group.

[0304] Then, the third intermediate compound is reacted with the fourth intermediate compound.

[0305] By performing the above steps, it is possible to manufacture a product where n is 1 and R is in equation (1). 1 With R 6 R 2 With R 5 R 3 With R 3’ It represents any one or more different compounds in the two PFPE chains.

[0306] (Third Manufacturing Method)

[0307] In manufacturing formula (1), n ​​is 2 and R is 2.3 and 2 R 3’ The three PFPE chains represented are the same, R 4 The two linking groups are identical and R 1 -R 2 -with R 6 -R 5 - For the same compound, the manufacturing method shown below can be used.

[0308] First, prepare R at the center of the molecule corresponding to equation (1). 3’ A fluorinated compound with hydroxymethyl (-CH2OH) groups configured at both ends of a perfluoropolyether chain. Next, the hydroxyl groups of the hydroxymethyl groups at the two ends of the fluorinated compound are reacted with a compound having a corresponding R... 4 The halogen compound reacts with the epoxy group (first reaction). Thus, R is obtained at the center of the molecule corresponding to formula (1). 3’ Intermediate compound 1, which has epoxy groups at both ends of the perfluoropolyether chain.

[0309] Next, prepare R corresponding to equation (1) 3 (=R 6 Side R 3’ A fluorinated compound having hydroxymethyl (-CH2OH) groups at both ends of a perfluoropolyether chain. Next, the hydroxyl group of the hydroxymethyl group at one end of the fluorinated compound is reacted with an R group having the form of formula (1). 1 -R 2 - group (= becomes R) 6 -R 5 The reaction of the epoxide with the - group (second reaction) yields a compound corresponding to R. 3 (=R 6 Side R 3’ One end of the perfluoropolyether chain has a corresponding R 1 -R 2 - group (=corresponding to R) 6 -R 5 Intermediate compound 2 (with a group of -).

[0310] As having become R in equation (1) 1 -R 2 - group (= becomes R) 6 -R 5 Epoxy compounds with the group (-) can be used in the same way as the first manufacturing method, for example, compounds represented by the above formulas (7-1a) to (7-1c), (7-2a) to (7-2c), (7-3), (7-4), etc.

[0311] In the case of synthesizing intermediate compound 2 by reacting the above-mentioned fluorine compound with the above-mentioned epoxy compound, the hydroxyl groups of the above-mentioned epoxy compound can be protected with an appropriate protecting group before reacting with the above-mentioned fluorine compound.

[0312] Then, the hydroxyl group of the hydroxymethyl group at one end of the intermediate compound 2 reacts with the epoxy groups at both ends of the intermediate compound 1 (third reaction).

[0313] By performing the above steps, it is possible to manufacture the product in formula (1) where n is 2 and R is 1. 3 and 2 R 3’ The three PFPE chains represented are the same, R 4 The two linking groups are identical and R 1 -R 2 -with R 6 -R 5 - The same compound.

[0314] In this embodiment, the second reaction is performed after the first reaction, but the first reaction may also be performed after the second reaction.

[0315] (Manufacturing Method 4)

[0316] In manufacturing formula (1), n ​​is 2 and R is 2. 4 The two linking groups are identical and R 1 With R 6 R 2 With R 5 R 3 With R 6 Side R 3’ If there are more than one different compound in the PFPE chain, the manufacturing method shown below can be used.

[0317] First, the first reaction is carried out in the same manner as the third manufacturing method to produce intermediate compound 1.

[0318] Next, in the second reaction, synthesis occurs at the reaction corresponding to R. 3 One end of the perfluoropolyether chain has a corresponding R 1 -R 2 Intermediate compound 2a of the - group. Furthermore, in the second reaction, the intermediate compound corresponding to R is synthesized. 6 Side R 3’ One end of the perfluoropolyether chain has a corresponding R 6 -R 5 Intermediate compound 2b of the - group.

[0319] Then, in a third reaction, intermediate compound 2a and intermediate compound 2b are sequentially reacted with the epoxy groups disposed at each end of intermediate compound 1.

[0320] By performing the above procedure, a compound in which n is 2, R 4 is the same and R 1 is the same as R 6 , R 2 is the same as R 5 , R 3 is the same as R 6 , and R 3’ is the same as R 3 can be manufactured.

[0321] (5th manufacturing method)

[0322] In the case of manufacturing a compound in which n is 2, R 3’ is the same, R 4 is the same, R 1 is different, and R 2 is the same as R 6 is the same as R 5 , the manufacturing method shown below can be employed.

[0323] First, in a first reaction, a fluorine-based compound in which a hydroxymethyl group (-CH2OH) is disposed at each end of a perfluoropolyether chain corresponding to R 3’ in the middle of the molecule in formula (1) is prepared. Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the above fluorine-based compound is reacted with a halogen compound having an epoxy group corresponding to one of the two linking groups represented by R 4 . Next, the hydroxyl group of the hydroxymethyl group disposed at the other end of the above fluorine-based compound is reacted with a halogen compound having an epoxy group corresponding to the other of the two linking groups represented by R 4 . Thus, an intermediate compound 1a having epoxy groups corresponding to the two linking groups represented by R 3’ at each end of the perfluoropolyether chain corresponding to R 4 in the middle of the molecule in formula (1) is obtained.

[0324] Next, the second reaction is performed by the same operation as in the 3rd manufacturing method to manufacture intermediate compound 2.

[0325] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the above intermediate compound 2 is reacted with the epoxy groups disposed at both ends of the above intermediate compound 1a (third reaction).

[0326] By performing the above procedure, a compound of formula (1) in which n is 2, R 3 and 2 R 3’ representing three PFPE chains are the same, R 4 representing two linking groups are different and R 1 - R 2 - is the same as R 6 - R 5 - is the same as R

[0327] The fluorine-containing ether compound of the present embodiment is a compound represented by formula (1), and has a skeleton in which a plurality of perfluoropolyether chains (R 4 ) and methylene are sequentially bonded to connect a 2-valent linking group (R 3 and R 3’ ) having one or more polar groups, and methylene, a 2-valent linking group (R 2 and R 5 ) having one or more polar groups, and a terminal group (R 1 and R 6 ) are sequentially bonded on both sides of the skeleton. Also, at least one of R 1 and R 6 is a group in which a carbonyl carbon atom or a nitrogen atom constituting an amide bond is bonded to a carbon atom of an organic group having 1 to 8 carbon atoms. Therefore, the chemical resistance and wear resistance of a lubricating layer formed on a protective layer using a lubricant containing the fluorine-containing ether compound of the present embodiment are good, and the effect of suppressing corrosion of a magnetic recording medium is high.

[0328] [Lubricant for magnetic recording medium]

[0329] The lubricant for a magnetic recording medium of the present embodiment contains the fluorine-containing ether compound represented by the above formula (1).

[0330] For the lubricant of the present embodiment, a known material used as a material for a lubricant can be mixed and used as needed, as long as the characteristics due to the inclusion of the fluorine-containing ether compound represented by the above formula (1) are not impaired.

[0331] As specific examples of the known material, FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco), and the like can be given. The number average molecular weight of the known material used in combination with the lubricant of the present embodiment is preferably 1000 to 10000.

[0332] In the case where the lubricant of the present embodiment contains a material other than the fluorine-containing ether compound represented by the above formula (1), the content of the fluorine-containing ether compound represented by the above formula (1) in the lubricant of the present embodiment is preferably 50% by mass or more, more preferably 70% by mass or more.

[0333] The lubricant of the present embodiment can form a lubricating layer having excellent chemical resistance and wear resistance and high effect of suppressing corrosion of a magnetic recording medium, because it contains the fluorine-containing ether compound represented by the above formula (1).

[0334] [Magnetic recording medium]

[0335] The magnetic recording medium of the present embodiment is a magnetic recording medium in which at least a magnetic layer, a protective layer, and a lubricating layer are sequentially provided on a substrate.

[0336] In the magnetic recording medium of the present embodiment, one or two or more underlayers can be provided between the substrate and the magnetic layer as needed. In addition, at least one of an adhesion layer and a soft magnetic layer can be provided between the underlayer and the substrate.

[0337] Figure 1 A schematic cross-sectional view of one embodiment of the magnetic recording medium of the present application is shown.

[0338] The magnetic recording medium 10 of the present embodiment is formed in a structure in which an adhesion layer 12, a soft magnetic layer 13, a first underlayer 14, a second underlayer 15, a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are sequentially provided on a substrate 11.

[0339] "Substrate"

[0340] As the substrate 11, for example, a non-magnetic substrate obtained by forming a film made of NiP or NiP alloy on a base made of a metal or an alloy material such as Al or Al alloy, or the like can be used.

[0341] In addition, as the substrate 11, a non-magnetic substrate made of a non-metal material such as glass, ceramic, silicon, silicon carbide, carbon, resin, or the like can be used, and a non-magnetic substrate obtained by forming a film of NiP or NiP alloy on a base made of these non-metal materials can be used.

[0342] "Adhesion layer"

[0343] The adhesion layer 12 prevents the progress of corrosion of the substrate 11 that occurs when the substrate 11 and the soft magnetic layer 13 to be provided on the adhesion layer 12 are arranged in abutment.

[0344] The material of the adhesion layer 12 can be appropriately selected from, for example, Cr, Cr alloy, Ti, Ti alloy, CrTi, NiAl, AlRu alloy, or the like. The adhesion layer 12 can be formed, for example, by a sputtering method.

[0345] "Soft magnetic layer"

[0346] 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 stacked in this order. That is, the soft magnetic layer 13 preferably has a structure in which the upper and lower soft magnetic films of the intermediate layer are coupled in an antiferromagnetic coupling (AFC) by interposing the intermediate layer made of a Ru film between the two soft magnetic films.

[0347] As the material of the first soft magnetic film and the second soft magnetic film, CoZrTa alloy, CoFe alloy, or the like can be given.

[0348] It is preferable to add any one of Zr, Ta, and Nb to the CoFe alloy used for the first soft magnetic film and the second soft magnetic film. Thereby, amorphization of the first soft magnetic film and the second soft magnetic film can be promoted. As a result, the orientation property of the first underlayer (seed layer) can be improved, and the flying height of the magnetic head can be reduced.

[0349] The soft magnetic layer 13 can be formed, for example, by a sputtering method.

[0350] "First underlayer"

[0351] The first underlayer 14 is a layer that controls the orientation and crystal size of the second underlayer 15 and the magnetic layer 16 provided thereon.

[0352] As the first underlayer 14, a base layer composed of, for example, a Cr layer, a Ta layer, a Ru layer, or a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, a CrTi alloy layer, or the like can be given.

[0353] The first underlayer 14 can be formed, for example, by a sputtering method.

[0354] "Second underlayer"

[0355] The second underlayer 15 is a layer that is controlled in such a manner that the orientation of the magnetic layer 16 is improved. The second underlayer 15 is preferably a layer made of Ru or a Ru alloy.

[0356] The second underlayer 15 can be a layer composed of one layer, or can be composed of multiple layers. In the case where the second underlayer 15 is composed of multiple layers, all the layers can be composed of the same material, or at least one layer can be composed of a different material.

[0357] The second underlayer 15 can be formed, for example, by a sputtering method.

[0358] "Magnetic layer"

[0359] The magnetic layer 16 is made of a magnetic film whose easy magnetization axis is oriented in a direction perpendicular or horizontal to the plane of the substrate. The magnetic layer 16 is a layer containing Co and Pt. The magnetic layer 16 can also be a layer containing an oxide, Cr, B, Cu, Ta, Zr, or the like, in order to improve SNR characteristics.

[0360] As the oxide contained in the magnetic layer 16, SiO2, SiO, Cr2O3, CoO, Ta2O3, TiO2, or the like can be given.

[0361] The magnetic layer 16 can be composed of one layer, or can be composed of a plurality of magnetic layers containing different materials.

[0362] For example, in the case where the magnetic layer 16 is composed of three layers of a first magnetic layer, a second magnetic layer, and a third magnetic layer, stacked in this order from the bottom, the first magnetic layer is preferably a granular structure formed of a material containing Co, Cr, Pt, and further containing an oxide. As the oxide contained in the first magnetic layer, an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, or the like is preferably used. Of these, TiO2, Cr2O3, SiO2, or the like can be particularly suitably used. Further, the first magnetic layer is preferably made of a composite oxide to which two or more oxides are added. Of these, Cr2O3-SiO2, Cr2O3-TiO2, SiO2-TiO2, or the like can be particularly suitably used.

[0363] The first magnetic layer can contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, in addition to Co, Cr, Pt, and an oxide.

[0364] In the second magnetic layer, the same material as the first magnetic layer can be used. The second magnetic layer is preferably a granular structure.

[0365] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, Pt, and not containing an oxide. The third magnetic layer can contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, Mn, in addition to Co, Cr, Pt.

[0366] In the case where the magnetic layer 16 is formed of a plurality of magnetic layers, a non-magnetic layer is preferably provided between adjacent magnetic layers. In the case where the magnetic layer 16 is composed of three layers of a first magnetic layer, a second magnetic layer, and a third magnetic layer, a non-magnetic layer is preferably provided between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.

[0367] The non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16 can be appropriately formed of, for example, Ru, a Ru alloy, a CoCr alloy, a CoCrXl alloy (Xl represents one or two or more elements selected from the group consisting of Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Ti, V, and B), or the like.

[0368] In the non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16, an alloy material containing an oxide, a metal nitride, or a metal carbide is preferably used. Specifically, as the oxide, for example, SiO2, Al2O3, Ta2O5, Cr2O3, MgO, Y2O3, TiO2, or the like can be used. As the metal nitride, for example, AlN, Si3N4, TaN, CrN, or the like can be used. As the metal carbide, for example, TaC, BC, SiC, or the like can be used.

[0369] The non-magnetic layer can be formed, for example, by a sputtering method.

[0370] In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer in which the easy magnetization axis is oriented in the perpendicular direction with respect to the substrate surface. The magnetic layer 16 can also be an in-plane magnetic recording magnetic layer.

[0371] The magnetic layer 16 can be formed by any of the conventionally known methods such as an evaporation method, an ion beam sputtering method, a magnetron sputtering method, or the like. The magnetic layer 16 is typically formed by a sputtering method.

[0372] "Protective Layer"

[0373] The protective layer 17 protects the magnetic layer 16. The protective layer 17 can be formed of one layer or can be formed of a plurality of layers. As the protective layer 17, a carbon-based protective layer, particularly an amorphous carbon protective layer, can be preferably used. If the protective layer 17 is a carbon-based protective layer, the interaction with the polar group (particularly the hydroxyl group) contained in the fluorine-containing ether compound in the lubricating layer 18 is further increased, and thus is preferred.

[0374] The adhesion of the carbon-based protective layer to the lubricating layer 18 can be controlled by making the carbon-based protective layer a hydrogenated carbon and / or a nitrogenated carbon and adjusting the hydrogen content and / or the nitrogen content in the carbon-based protective layer. The hydrogen content in the carbon-based protective layer is preferably 3 atomic % to 20 atomic % when measured by a hydrogen forward scattering method (HFS). In addition, the nitrogen content in the carbon-based protective layer is preferably 4 atomic % to 15 atomic % when measured by an X-ray photoelectron spectroscopy method (XPS).

[0375] The hydrogen and / or nitrogen contained in the carbon-based protective layer do not need to be uniformly contained throughout the entire carbon-based protective layer. The carbon-based protective layer is suitable, for example, as a tilted layer, i.e., containing nitrogen on the lubrication layer 18 side of the protective layer 17 and hydrogen on the magnetic layer 16 side of the protective layer 17. In this case, the adhesion between the magnetic layer 16 and the lubrication layer 18 and the carbon-based protective layer is further improved.

[0376] The thickness of the protective layer 17 is preferably 1 nm to 7 nm. If the thickness of the protective layer 17 is 1 nm or more, the performance of the protective layer 17 can be fully obtained. If the thickness of the protective layer 17 is 7 nm or less, it is preferred from the viewpoint of thinning the protective layer 17.

[0377] The film formation method for the protective layer 17 can be sputtering using a target containing carbon, CVD (chemical vapor deposition) using hydrocarbon raw materials such as ethylene and toluene, or IBD (ion beam deposition).

[0378] When forming a carbon-based protective layer as protective layer 17, film deposition can be performed, for example, using DC magnetron sputtering. In particular, when forming a carbon-based protective layer as protective layer 17, it is preferable to form an amorphous carbon protective layer using plasma CVD. The amorphous carbon protective layer obtained by plasma CVD has a uniform surface and low roughness.

[0379] "Lubrication layer"

[0380] The lubricating layer 18 prevents contamination of the magnetic recording medium 10. In addition, the lubricating layer 18 reduces the friction of the magnetic head of the magnetic recording and playback device that slides on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10.

[0381] like Figure 1 As shown, the lubricating layer 18 is formed on the protective layer 17 in contact with it. The lubricating layer 18 is formed by coating the protective layer 17 with the lubricant for magnetic recording media of the above embodiment. Therefore, the lubricating layer 18 contains the fluorinated ether compound described above.

[0382] When the protective layer 17 disposed beneath the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 bonds with the protective layer 17 with a particularly high bonding strength. As a result, it is easy to obtain a magnetic recording medium 10 that covers the surface of the protective layer 17 with a high coverage even when the thickness of the lubricating layer 18 is relatively thin, and it is possible to effectively prevent contamination of the surface of the magnetic recording medium 10.

[0383] The average film thickness of the lubricating layer 18 is preferably... More preferably If the average film thickness of the lubricating layer 18 is 0.5 nm or more, the lubricating layer 18 does not become island-like or mesh-like, but is formed with a uniform film thickness. Therefore, the surface of the protective layer 17 can be coated with the lubricating layer 18 at a high coating rate. In addition, by making the average film thickness of the lubricating layer 18 2.0 nm or less, the lubricating layer 18 can be sufficiently thinned, and the amount of floating of the magnetic head can be sufficiently reduced.

[0384] "Method for forming lubricating layer"

[0385] To form the lubricating layer 18, a method such as the following can be mentioned: a magnetic recording medium at an intermediate stage of manufacture in which the layers up to the protective layer 17 are formed on the substrate 11 is prepared, and a lubricating layer-forming solution is applied to the protective layer 17.

[0386] The lubricating layer-forming solution can be obtained by dispersing and dissolving the magnetic recording medium lubricant of the above-described embodiment in a solvent as needed and making the viscosity and concentration suitable for the application method.

[0387] As the solvent used in the lubricating layer-forming solution, a fluorine-based solvent such as, for example, BARTRELL (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) or the like can be mentioned.

[0388] The application method of the lubricating layer-forming solution is not particularly limited, and a method such as, for example, spin coating, spray coating, paper coating, dipping, or the like can be mentioned.

[0389] In the case of using the dipping method, for example, the following method can be used. First, the substrate 11 on which the layers up to the protective layer 17 have been formed is dipped in the lubricating layer-forming solution charged in a dipping tank of a dip coater. Next, the substrate 11 is lifted from the dipping tank at a predetermined speed. By this, the lubricating layer-forming solution is applied to the surface of the protective layer 17 of the substrate 11.

[0390] By using the dipping method, the lubricating layer-forming solution can be uniformly applied to the surface of the protective layer 17, and the lubricating layer 18 can be formed on the protective layer 17 with a uniform film thickness.

[0391] In the present embodiment, it is preferable to perform heat treatment on the substrate 11 on which the lubricating layer 18 is formed. By performing heat treatment, the adhesion of the lubricating layer 18 to the protective layer 17 is improved, and the adhesion of the lubricating layer 18 to the protective layer 17 is improved.

[0392] The heat treatment temperature is preferably set to 100°C to 180°C, and more preferably to 100°C to 160°C. If the heat treatment temperature is above 100°C, the effect of improving the adhesion between the lubricating layer 18 and the protective layer 17 can be sufficiently achieved. Furthermore, by keeping the heat treatment temperature below 180°C, thermal decomposition of the lubricating layer 18 caused by heat treatment can be prevented. The heat treatment time can be appropriately adjusted according to the heat treatment temperature, and is preferably set to 10 minutes to 120 minutes.

[0393] In this embodiment, in order to further improve the adhesion of the lubricating layer 18 to the protective layer 17, the lubricating layer 18 can be treated with ultraviolet (UV) irradiation before or after heat treatment.

[0394] The magnetic recording medium 10 of this embodiment is a magnetic recording medium on a substrate 11 in which at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are sequentially disposed. In the magnetic recording medium 10 of this embodiment, a lubricating layer 18 containing the aforementioned fluorinated ether compound is formed on the protective layer 17 in a contact manner. This lubricating layer 18 has excellent adhesion even when the film thickness is relatively thin, good chemical resistance and abrasion resistance, and a high effect on inhibiting corrosion of the magnetic recording medium. Therefore, the magnetic recording medium 10 of this embodiment is excellent in terms of reliability, especially in terms of inhibition of silicon contamination and durability. As a result, the magnetic recording medium 10 of this embodiment can reduce the magnetic head float (for example, to less than 10 nm) and can operate stably for a long time even in harsh environments that accompany the diversification of applications. Therefore, the magnetic recording medium 10 of this embodiment is suitable as a disk for use in disk drives, especially in LUL (Load Unload) type disk drives.

[0395] Example

[0396] The present invention will now be described in more detail using examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

[0397] [Example 1]

[0398] The compound represented by formula (A) above was obtained by the method shown below.

[0399] Under a nitrogen atmosphere, HOCH2CF2O(CF2CF2O) was added to a 100mL round-bottom flask. h (CF2O) iCF2CH2OH (h in the formula represents the average degree of polymerization and is 3.2, and i represents the average degree of polymerization and is 3.2.) 20 g, the compound represented by the above formula (7-1a) 4.15 g, and t-butyl alcohol 20 mL were stirred at room temperature until they became uniform, and a mixture was prepared. To the mixture was added potassium t-butoxide 1.60 g, and the reaction was performed by stirring at 70°C for 16 hours.

[0400] Note that the compound represented by the formula (7-1a) is synthesized by reacting 3-hydroxypropionamide with epi-bromohydrin.

[0401] The resulting reaction product was returned to room temperature after the reaction, transferred to a separatory funnel containing 100 mL of water, and extracted with 100 mL of ethyl acetate three times. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After the drying agent was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 8.69 g of the compound represented by the following formula (15) as an intermediate.

[0402]

[0403] (Rf1in the formula (15) is the PFPE chain represented by the above formula (4-1). In Rf1, h represents the average degree of polymerization and is 3.2, and i represents the average degree of polymerization and is 3.2.)

[0404] Next, 8.69 g of the above obtained intermediate, i.e., the compound represented by the formula (15), 0.845 g of epi-bromohydrin, and 10 mL of t-butyl alcohol were put into a 100 mL vial, and stirred at room temperature until they became uniform under a nitrogen atmosphere. To the uniform liquid was added 0.92 g of potassium t-butoxide, and the reaction was performed by stirring at 70°C for 23 hours.

[0405] The resulting reaction liquid was returned to room temperature after the reaction, transferred to a separatory funnel containing 100 mL of water, and extracted with 100 mL of ethyl acetate three times. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After the drying agent was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 5.74 g of the compound (A) (Rf1in the formula (A) is the PFPE chain represented by the above formula (4-1). In 2 Rf1, h represents the average degree of polymerization and is 3.2, and i represents the average degree of polymerization and is 3.2.).

[0406] The resulting compound (A) was subjected to H-NMR and F-NMR measurement, and the structure was identified based on the following results. 1 H-NMR and F-NMR measurement, and the structure was identified based on the following results. 19 F-NMR measurement, and the structure was identified based on the following results.

[0407] 1H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (22H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0408] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0409] [Example 2]

[0410] The compound represented by the above formula (B) was obtained by the following method.

[0411] The same operation as in Example 1 was performed, except that the compound represented by formula (7-2a) was used instead of the compound represented by formula (7-1a) in Example 1, to obtain 5.89 g of compound (B) (Rf1in formula (B) is a PFPE chain represented by the above formula (4-1). Of the two Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0412] Note that the compound represented by formula (7-2a) was synthesized by reacting N-(2-hydroxyethyl)acetamide with phenylbromide.

[0413] The obtained compound (B) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0414] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (6H), 3.40-4.00 (26H), 4.10-4.20 (8H), 6.30-6.50 (2H)

[0415] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0416] [Example 3]

[0417] The compound represented by the above formula (C) was obtained by the following method.

[0418] The same operation as in Example 1 was conducted, except that the compound represented by formula (7-2b) was used instead of the compound represented by formula (7-1a) in Example 1, to obtain 6.08 g of the compound (C) (Rf1in formula (C) is a PFPE chain represented by the above formula (4-1). Of the two Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0419] Note that the compound represented by formula (7-2b) was synthesized by reacting 4-aminobutanol with acetyl chloride to obtain an intermediate, and reacting the intermediate with phenylbromomagnesium.

[0420] The obtained compound (C) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0421] 1 H-NMR (Acetone-D6): δ [ppm] = 1.20-1.80 (8H), 3.40-4.00 (26H), 4.10-4.20 (8H), 6.30-6.50 (2H)

[0422] 19 F-NMR (Acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0423] [Example 4]

[0424] The compound represented by the above formula (D) was obtained by the method shown below.

[0425] The same operation as in Example 1 was conducted, except that the compound represented by formula (7-2c) was used instead of the compound represented by formula (7-1a) in Example 1, to obtain 6.28 g of the compound (D) (Rf1in formula (D) is a PFPE chain represented by the above formula (4-1). Of the two Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0426] Note that the compound represented by formula (7-2c) was synthesized by reacting 6-aminohexanol with acetyl chloride to obtain an intermediate, and reacting the intermediate with phenylbromomagnesium.

[0427] The obtained compound (D) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0428] 1H-NMR (acetone-D6): δ [ppm] = 1.20-1.80 (16H), 3.40-4.00 (26H), 4.10-4.20 (8H), 6.30-6.50 (2H)

[0429] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0430] [Example 5]

[0431] The compound represented by the above formula (E) was obtained by the following method.

[0432] The same operation as in Example 1 was performed, except that the compound represented by formula (7-3) was used instead of the compound represented by formula (7-la) in Example 1, to obtain 6.14 g of the compound (E) (Rf1in formula (E) is the PFPE chain represented by the above formula (4-la). Of the two Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0433] Note that the compound represented by formula (7-3) was synthesized by reacting 4-hydroxybenzamide with phenylthiol.

[0434] The obtained compound (E) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0435] 1 H-NMR (acetone-D6): δ [ppm] = 1.20-1.80 (16H), 3.40-4.00 (26H), 4.10-4.20 (8H), 6.30-6.50 (2H)

[0436] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0437] [Example 6]

[0438] The compound represented by the above formula (F) was obtained by the following method.

[0439] The same operation as in Example 1 was conducted, except that the compound represented by formula (7-4) was used instead of the compound represented by formula (7-1a) in Example 1, to obtain 6.09 g of the compound (F) (Rf1in formula (F) is a PFPE chain represented by the above formula (4-1). Of the two Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0440] Note that the compound represented by formula (7-4) was synthesized by reacting N-(4-hydroxyphenyl)acetamide with epibromohydrin.

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

[0442] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (6H), 3.40-4.00 (18H), 4.10-4.20 (8H), 6.30-6.50 (2H), 7.30-7.80 (8H)

[0443] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 -88.5 (26F)

[0444] [Example 7]

[0445] The compound represented by the above formula (G) was obtained by the following method.

[0446] The same operation as in Example 1 was conducted, except that the compound represented by formula (7-1b) was used instead of the compound represented by formula (7-1a) in Example 1, to obtain 5.95 g of the compound (G) (Rf1in formula (G) is a PFPE chain represented by the above formula (4-1). Of the two Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0447] Note that the compound represented by formula (7-1b) was synthesized by reacting 3-hydroxypropionamide with allyl glycidyl ether to obtain an intermediate, and subjecting the intermediate to action of meta-chloroperoxybenzoic acid.

[0448] The obtained compound (G) was subjected to the following. 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0449] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (34H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0450] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 -88.5 (26F)

[0451] [Example 8]

[0452] The compound represented by the above formula (H) was obtained by the following method.

[0453] The compound represented by the above formula (15) was reacted with phenylthiol to thereby obtain, as an intermediate, the compound represented by the following formula (16).

[0454]

[0455] (Rf1in the formula (16) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.)

[0456] Next, 4.23 g of the above obtained intermediate, the compound represented by the formula (16), 4.15 g of the intermediate of Example 7, the compound represented by the following formula (17), and 10 mL of tert-butyl alcohol were put into a 100 mL vial under a nitrogen atmosphere, and stirred at room temperature until it became uniform. To the uniform liquid, 0.92 g of potassium tert-butoxide was added, and it was stirred at 70°C for 23 hours to thereby make it react.

[0457]

[0458] (Rf1in the formula (17) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.)

[0459] The obtained reaction liquid was returned to room temperature after the reaction, transferred to a separatory funnel equipped with 100 mL of water, and extracted with 100 mL of ethyl acetate three times. The organic layer was washed with water, and dehydrated with anhydrous sodium sulfate. After the drying agent was separated by filtration, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to thereby obtain 4.52 g of the compound (H) (Rf1in the formula (H) is the PFPE chain represented by the above formula (4-1). In 2 Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.).

[0460] The obtained compound (H) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0461] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (28H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0462] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 -88.5 (26F)

[0463] [Example 9]

[0464] The compound represented by the above formula (I) was obtained by the following method.

[0465] Using a compound represented by formula (7-1c) instead of the compound represented by formula (7-1a) of Example 1, the same operation as in Example 1 was performed to obtain 6.02 g of compound (I) (Rf1in formula (I) is a PFPE chain represented by the above formula (4-1). Of the 2 Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0466] Note that the compound represented by formula (7-1c) was synthesized by reacting 3-hydroxypropionamide with 4-bromo-l-butene to obtain an intermediate, and subjecting the intermediate to action of meta-chloroperoxybenzoic acid.

[0467] The obtained compound (I) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0468] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (28H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0469] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 -88.5 (26F)

[0470] [Example 10]

[0471] The compound represented by the above formula (J) was obtained by the following method.

[0472] The compound represented by the above formula (15) of Example 1 was reacted with 4-bromo-l-butene, and then subjected to the action of meta-chloroperoxybenzoic acid, whereby the compound represented by the following formula (18) as an intermediate was obtained.

[0473]

[0474] (Rf1in formula (18) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.)

[0475] The same operation as in Example 8 was performed, except that the compound represented by formula (18) was used instead of the compound represented by formula (16) of Example 8, and the compound represented by formula (15) was used instead of the compound represented by formula (17), whereby 5.89 g of the compound (J) (Rf1in formula (J) is the PFPE chain represented by the above formula (4-1). In 2 Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.) was obtained.

[0476] The obtained compound (J) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0477] 1 H-NMR (acetone-D6): δ [ppm] = 1.20-1.80 (2H), 1.90-2.05 (4H), 3.40-4.00 (22H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0478] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0479] [Example 11]

[0480] The compound represented by the above formula (K) was obtained by the following method.

[0481] Into a 200 mL vial under a nitrogen atmosphere, HOCH2CF2O(CF2CF2O) h (CF2O)i CF2CH2OH (h in the formula represents 3.2 as the average polymerization degree, and i represents 3.2 as the average polymerization degree.) 14 g, a compound represented by the following formula (19) 2.4 g, and t-butyl alcohol 14 mL were stirred at room temperature until they became uniform. Further, potassium t-butoxide 0.45 g was added to the uniform liquid, and the mixture was stirred at 70°C for 16 hours to allow the reaction to proceed.

[0482]

[0483] The compound represented by formula (19) was synthesized by oxidizing a compound in which ethylene glycol monomallyl ether was protected with dihydropyran.

[0484] The resulting reaction product was cooled to 25°C after the reaction, transferred to a separatory funnel containing 100 mL of water, and extracted with 100 mL of ethyl acetate three times. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After the drying agent was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 6.62 g of a compound represented by the following formula (20) as an intermediate.

[0485]

[0486] (Rf1in formula (20) is a PFPE chain represented by the above formula (4-1). In Rf1, h represents 3.2 as the average polymerization degree, and i represents 3.2 as the average polymerization degree.)

[0487] Next, 3.63 g of the above obtained intermediate, the compound represented by formula (20), 4.05 g of the intermediate of Example 8, the compound represented by formula (16), and 10 mL of t-butyl alcohol were put into a 100 mL vial, and stirred at room temperature until they became uniform under a nitrogen atmosphere. Potassium t-butoxide 0.90 g was added to the uniform liquid, and the mixture was stirred at 70°C for 23 hours to allow the reaction to proceed.

[0488] The resulting reaction liquid was returned to room temperature after the reaction, 18 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at room temperature for 2 hours. The mixture was transferred to a separatory funnel containing 100 mL of water, and extracted with 100 mL of ethyl acetate three times. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After the drying agent was separated by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 4.03 g of a compound (K) (Rf1in formula (K) is a PFPE chain represented by the above formula (4-1). In 2 Rf1, h represents 3.2 as the average polymerization degree, and i represents 3.2 as the average polymerization degree.).

[0489] The obtained compound (K) was subjected to 1 H-NMR and 19 The structure was identified from the following results of F-NMR measurement.

[0490] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (2H), 3.40-4.00 (25H), 4.10-4.20 (8H), 6.30-6.70 (2H)

[0491] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0492] [Example 12]

[0493] The compound represented by the above formula (L) was obtained by the following method.

[0494] The same operation as in Example 8 was performed, except that the compound represented by formula (21) was used instead of the compound represented by formula (17), to obtain 5.40 g of compound (L) (Rf1in formula (L) is a PFPE chain represented by the above formula (4-1). Of Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.).

[0495] Note that the compound represented by formula (21) was synthesized according to Patent Literature 5.

[0496]

[0497] (Rf1in formula (21) is a PFPE chain represented by the above formula (4-1). Of Rf1, h representing the average polymerization degree indicates 3.2, and i representing the average polymerization degree indicates 3.2.)

[0498] The obtained compound (L) was subjected to 1 H-NMR and 19 The structure was identified from the following results of F-NMR measurement.

[0499] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (2H), 3.40-4.00 (25H), 4.10-4.20 (8H), 6.30-6.70 (2H)

[0500] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0501] [Example 13]

[0502] The compound represented by the above formula (M) was obtained by the following method.

[0503] The same operation as in Example 8 was performed, except that the compound represented by formula (22) was used instead of the compound represented by formula (17) in Example 8, to obtain 5.40 g of the compound (M) (Rf1in formula (M) is a PFPE chain represented by the above formula (4-1). Of Rf1, h representing the average degree of polymerization indicates 3.2, and i representing the average degree of polymerization indicates 3.2.).

[0504] Note that the compound represented by formula (22) was synthesized according to Patent Literature 5.

[0505]

[0506] (Rf1in formula (22) is a PFPE chain represented by the above formula (4-1). Of Rf1, h representing the average degree of polymerization indicates 3.2, and i representing the average degree of polymerization indicates 3.2.)

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

[0508] 1 H-NMR (acetone-D6): δ [ppm] = 1.90 - 2.05 (2H), 3.40 - 4.00 (22H), 4.10 - 50 (9H)

[0509] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0510] [Example 14]

[0511] The compound represented by the above formula (N) was obtained by the following method.

[0512] HOCH2CF2CF2(OCF2CF2CF2) ja compound represented by OCF2CF2CH2OH (in the formula, j representing the average degree of polymerization is 2.6) instead of HOCH2CF2O(CF2CF2O) in Example 1 h (CF2O) i CF2CH2OH instead of HOCH2CF2O(CF2CF2O) in Example 1, the same operation as in Example 1 was performed to obtain 6.17 g of the compound (N) (in the formula (N), Rf2 is a PFPE chain represented by the above formula (4-2). Of the two Rf2, j representing the average degree of polymerization indicates 2.6).

[0513] The obtained compound (N) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0514] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (22H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0515] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 -83.0 (36F), -86.4 (8F), -124.3 (8F), -130.0 -129.0 (18F)

[0516] [Example 15]

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

[0518] HOCH2CF2CF2CF2(OCF2CF2CF2CF2) k OCF2CF2CF2CH2OH (in the formula, k representing the average degree of polymerization is 1.6) instead of HOCH2CF2O(CF2CF2O) in Example 1 h (CF2O) i CF2CH2OH instead of HOCH2CF2O(CF2CF2O) in Example 1, the same operation as in Example 1 was performed to obtain 6.17 g of the compound (N) (in the formula (N), Rf2 is a PFPE chain represented by the above formula (4-2). Of the two Rf2, j representing the average degree of polymerization indicates 2.6).

[0519] The obtained compound (O) was subjected to 1 H-NMR and 19The structure was identified based on the following results of F-NMR measurement.

[0520] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (22H), 4.10-4.20 (8H), 6.30-6.70 (4H)

[0521] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 -83.0 (34F), -122.5 (8F), -126.0 (13F), -129.0 -128.0 (8F)

[0522] [Example 16]

[0523] The compound represented by the above formula (P) was obtained by the following method.

[0524] The compound represented by the above formula (P) was obtained by the following method. h (CF2O) i The compound represented by the above formula (P) was obtained by the following method.

[0525]

[0526] (Rf1in formula (23) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average polymerization degree represents 3.2, and i representing the average polymerization degree represents 3.2.)

[0527] Next, in the reaction of the compound represented by formula (15) in Example 1 with epihalohydrin, the compound represented by formula (23) was used instead of epihalohydrin, and the same operation as in Example 1 was performed, except for this, to obtain 4.75 g of the compound (P) (Rf1in formula (P) is the PFPE chain represented by the above formula (4-1). In 3 Rf1, h representing the average polymerization degree represents 3.2, and i representing the average polymerization degree represents 3.2.).

[0528] The obtained compound (P) was subjected to 1 H-NMR and 19 The structure was identified based on the following results of F-NMR measurement.

[0529] 1H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (28H), 4.10-4.20 (12H), 6.30-6.70 (4H)

[0530] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0531] [Example 17]

[0532] The compound represented by the above formula (Q) was obtained by the following method.

[0533] In the process of synthesizing the compound represented by formula (15), a compound represented by formula (7-2a) was used instead of the compound represented by formula (7-1a), and the same operation as in Example 16 was performed, except for this, to obtain 4.81 g of the compound (Q) (Rf1in formula (Q) is a PFPE chain represented by the above formula (4-1). Of the 3 Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

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

[0535] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (6H), 3.40-4.00 (32H), 4.10-4.20 (8H), 6.30-6.50 (2H)

[0536] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0537] [Example 18]

[0538] The compound represented by the above formula (R) was obtained by the following method.

[0539] In the procedure for synthesizing the compound represented by formula (15), a compound represented by formula (7-2b) was used instead of the compound represented by formula (7-1a), and the same operation as in Example 16 was performed, except for this, to obtain 4.89 g of the compound (R) (Rf1 in formula (R) is a PFPE chain represented by the above formula (4-1). Of the 3 Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2.).

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

[0541] 1 H-NMR (acetone-D6): δ [ppm] = 1.20-1.80 (8H), 3.40-4.00 (32H), 4.10-4.20 (8H), 6.30-6.50 (2H)

[0542] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0543] [Example 19]

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

[0545] In the procedure for synthesizing the compound represented by formula (15), a compound represented by formula (7-3) was used instead of the compound represented by formula (7-1a), and the same operation as in Example 16 was performed, except for this, to obtain 4.99 g of the compound (S) (Rf1 in formula (S) is a PFPE chain represented by the above formula (4-1). Of the 3 Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2.).

[0546] The obtained compound (S) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0547] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-4.00 (24H), 4.10-4.20 (12H), 6.30-6.70 (4H), 7.30-7.80 (8H)

[0548] 19F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0549] [Example 20]

[0550] The compound represented by the above formula (T) was obtained by the following method.

[0551] The compound represented by the above formula (T) was obtained by the following method. h (CF2O) i CF2CH2OH (h in the formula represents the average degree of polymerization of 3.2, and i represents the average degree of polymerization of 3.2.) was reacted with 4-bromo-l-butene, and then subjected to the action of meta-chloroperoxybenzoic acid, whereby the intermediate represented by formula (24) was obtained.

[0552] The same operation as in Example 16 was performed using the compound represented by formula (24) instead of the compound represented by formula (23) in Example 16, whereby 4.32 g of the compound (T) (Rf1in the formula (T) is the PFPE chain represented by the above formula (4-1). In Rf1, h represents the average degree of polymerization of 3.2, and i represents the average degree of polymerization of 3.2.) was obtained.

[0553]

[0554] (Rf1in the formula (24) is the PFPE chain represented by the above formula (4-1). In Rf1, h represents the average degree of polymerization of 3.2, and i represents the average degree of polymerization of 3.2.)

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

[0556] 1 H-NMR (acetone-D6): δ [ppm] = 1.20 - 1.80 (4H), 1.90 - 2.05 (4H), 3.40 - 4.00 (28H), 4.10 - 4.20 (12H), 6.30 - 6.70 (4H)

[0557] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0558] [Example 21]

[0559] The compound represented by the above formula (U) was obtained by the following method.

[0560] In the process of synthesizing the compound represented by formula (15), a compound represented by formula (7-1b) was used instead of the compound represented by formula (7-1a), and the same operation as in Example 16 was performed, except for this, to obtain 4.65 g of the compound (U) (Rf1in formula (U) is a PFPE chain represented by the above formula (4-1). Of the 3 Rf1, h representing the average degree of polymerization indicates 3.2, and i representing the average degree of polymerization indicates 3.2.).

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

[0562] 1 H-NMR (Acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (40H), 4.10-4.20 (12H), 6.30-6.70 (4H)

[0563] 19 F-NMR (Acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0564] [Example 22]

[0565] The compound represented by the above formula (V) was obtained by the following method.

[0566] In the process of synthesizing the compound represented by formula (15), a compound represented by formula (7-1c) was used instead of the compound represented by formula (7-1a), and the same operation as in Example 16 was performed, except for this, to obtain 4.41 g of the compound (V) (Rf1in formula (V) is a PFPE chain represented by the above formula (4-1). Of the 3 Rf1, h representing the average degree of polymerization indicates 3.2, and i representing the average degree of polymerization indicates 3.2.).

[0567] The obtained compound (V) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0568] 1H-NMR (acetone-D6): δ [ppm] = 1.20-1.80 (4H), 1.90-2.05 (4H), 3.40-4.00 (28H), 4.10-4.20 (12H), 6.30-6.70 (4H)

[0569] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0570] [Example 23]

[0571] The above compound represented by formula (W) was obtained by the following method.

[0572] In the step of reacting the compound represented by formula (20) with the compound represented by formula (16), an intermediate obtained by reacting the compound represented by formula (15) with the compound represented by formula (23) was used instead of the compound represented by formula (16), and otherwise the same operation as in Example 11 was performed to obtain 4.11 g of the compound (W) (Rf1in formula (W) is a PFPE chain represented by the above formula (4-1). Of the three Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0573] The obtained compound (W) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0574] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (2H), 3.40-4.00 (31H), 4.10-4.20 (12H), 6.30-6.70 (2H)

[0575] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0576] [Example 24]

[0577] The above compound represented by formula (X) was obtained by the following method.

[0578] The same operation as Example 23 was performed, except that a compound represented by formula (21) was used instead of the compound represented by formula (20), to obtain 4.31 g of compound (X) (Rf1in formula (X) is a PFPE chain represented by the above formula (4-1). Of the three Rf1, h representing the average degree of polymerization is 3.2, and i representing the average degree of polymerization is 3.2).

[0579] The obtained compound (X) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0580] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (2H), 2.40-2.60 (2H), 3.40-4.00 (28H), 4.10-4.20 (12H), 5.40-6.10 (3H), 6.30-6.70 (2H)

[0581] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 - -51.5 (13F), -78.5 (4F), -80.5 (4F), -91.0 - -88.5 (26F)

[0582] [Example 25]

[0583] The compound represented by the above formula (Y) was obtained by the following method.

[0584] HOCH2CF2CF2(OCF2CF2CF2) j OCF2CF2CH2OH (j representing the average degree of polymerization in the formula is 2.6.) represented compound (number average molecular weight: 700, molecular weight distribution: 1.1) was used instead of HOCH2CF2O(CF2CF2O) h (CF2O) i CF2CH2OH, except that the same operation as Example 16 was performed, to obtain 4.89 g of compound (Y) (Rf2in formula (Y) is a PFPE chain represented by the above formula (4-2). Of the three Rf2, j representing the average degree of polymerization is 2.6).

[0585] The obtained compound (Y) was subjected to 1 H-NMR and 19 F-NMR measurement, and the structure was identified based on the following results.

[0586] 1H-NMR (acetone-D6): δ [ppm] = 1.90-2.05 (4H), 3.40-4.00 (28H), 4.10-4.20 (12H), 6.30-6.70 (4H)

[0587] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 -83.0 (26F), -86.4 (8F), -124.3 (8F), -130.0 -129.0 (13F)

[0588] The structures of R 1 (amide group, organic group), R 2 , R 3 , R 3’ , R 4 , R 5 , R 6 (amide group, organic group), n.

[0589] [Table 1]

[0590]

[0591] [Table 2]

[0592]

[0593] [Comparative Example 1]

[0594] The compound represented by the following formula (AA) was synthesized by the method described in Patent Document 1.

[0595]

[0596] (Rf1in formula (AA) is a PFPE chain represented by the above formula (4-1). Of the two Rf1, h representing the average degree of polymerization is 7.0, and i is 0.)

[0597] [Comparative Example 2]

[0598] The compound represented by the following formula (AB) was synthesized by the method described in Patent Document 2.

[0599]

[0600] (Rf2in formula (AB) is a PFPE chain represented by the above formula (4-2). Of the two Rf2, j representing the average degree of polymerization is 4.0.)

[0601] [Comparative Example 3]

[0602] A compound represented by the following formula (AC) was synthesized by the method described in Patent Document 3.

[0603]

[0604] (Rf2in formula (AC) is a PFPE chain represented by the above formula (4-2). j, which represents the average degree of polymerization, is 4.0 in 3 Rf2.)

[0605] [Comparative Example 4]

[0606] A compound represented by the following formula (AD) was synthesized by the method described in Patent Document 4.

[0607]

[0608] (Rf1in formula (AD) is a PFPE chain represented by the above formula (4-1). h and i, which represent the average degree of polymerization, are each 4.5 in Rf1.)

[0609] The number average molecular weight (Mn) of the compounds obtained in Examples 1 to 25 and Comparative Examples 1 to 4 as described above was measured by the above-described method. The results thereof are shown in Table 3.

[0610] Next, the compounds obtained in Examples 1 to 25 and Comparative Examples 1 to 4 were used to prepare lubricating layer-forming solutions by the method shown below. Then, using the obtained lubricating layer-forming solutions, a lubricating layer of a magnetic recording medium was formed by the method shown below, to obtain the magnetic recording medium of Examples 1 to 25 and Comparative Examples 1 to 4.

[0611] "Lubricating layer-forming solution"

[0612] The compounds obtained in Examples 1 to 25 and Comparative Examples 1 to 4 were each dissolved in BURTRIL (registered trademark) XF (trade name, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) as a fluorine-based solvent, diluted with BURTRIL XF so as to have a film thickness of 100 nm when coated onto a protective layer, and prepared into a lubricating layer-forming solution.

[0613] "Magnetic recording medium"

[0614] A magnetic recording medium was prepared in which an adhesion layer, a soft magnetic layer, a first base layer, a second base layer, a magnetic layer, and a protective layer were sequentially provided on a substrate having a diameter of 65 mm. The protective layer was composed of carbon.

[0615] ​On the protective layer of the magnetic recording medium formed with the layers up to the protective layer, the lubricating layer-forming solution of Examples 1 to 25 and Comparative Examples 1 to 4 was applied by the dipping method. Note that the dipping method was performed under conditions of a dipping speed of 10 mm / sec, a dipping time of 30 sec, and a lifting speed of 1.2 mm / sec.

[0616] Then, the magnetic recording medium on which the lubricating layer-forming solution was applied was put into a thermostat, and the solvent in the lubricating layer-forming solution was removed, and heat treatment for improving the adhesion of the protective layer and the lubricating layer was performed at 120°C for 10 minutes, whereby the lubricating layer was formed on the protective layer, and a magnetic recording medium was obtained.

[0617] (Measurement of film thickness)

[0618] The film thickness of the lubricating layer possessed by the magnetic recording media of Examples 1 to 25 and Comparative Examples 1 to 4 obtained as described above was measured using FT-IR (trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific). The results are shown in Table 3.

[0619] Next, the magnetic recording media of Examples 1 to 25 and Comparative Examples 1 to 4 were subjected to the abrasion resistance test, the chemical resistance test, and the corrosion resistance test shown below.

[0620] (Abrasion resistance test)

[0621] Using a pin-on-disk type friction and wear tester, a 2-mm-diameter alumina ball as a contact member was made to slide on the lubricating layer of the magnetic recording medium under conditions of a load of 40 gf and a sliding speed of 0.25 m / sec, and the friction coefficient of the surface of the lubricating layer was measured. Then, the sliding time until the friction coefficient of the surface of the lubricating layer sharply increased was measured. The sliding time until the friction coefficient sharply increased was measured four times for each of the lubricating layers of the magnetic recording media, and the average value (time) thereof was taken as an index of the abrasion resistance of the lubricant coating film.

[0622] The results of the magnetic recording media using the compounds of Examples 1 to 25 and the compounds of Comparative Examples 1 to 4 are shown in Table 3, respectively. The evaluation of the abrasion resistance performed using the sliding time until the friction coefficient sharply increased was as described below.

[0623] ◎ (Good): 650 sec or more

[0624] ○ (Good): 550 sec or more and less than 650 sec

[0625] △ (Good): 450 sec or more and less than 550 sec

[0626] × (Not good): less than 450 sec

[0627] Note that the time until the friction coefficient sharply increases can be used as an index of the wear resistance of the lubricating layer for the following reason. That is, for the lubricating layer of the magnetic recording medium, wear progresses by use of the magnetic recording medium, and if the lubricating layer disappears due to wear, the contact member directly contacts the protective layer, and the friction coefficient sharply increases. It is considered that the time until the friction coefficient sharply increases is also correlated with the friction test.

[0628] (Chemical substance resistance test)

[0629] The contamination of the magnetic recording medium caused by environmental substances that generate contaminating substances in a high-temperature environment was investigated by the following method. As the environmental substance, Si ions were used, and as the amount of the contaminating substance that contaminates the magnetic recording medium due to the environmental substance, the Si adsorption amount was measured.

[0630] Specifically, the magnetic recording medium as the evaluation object was left in the presence of silicone-based Si rubber in a high-temperature environment at a temperature of 85°C and a humidity of 0% for 240 hours. Next, the Si adsorption amount present on the surface of the magnetic recording medium was analyzed and measured by secondary ion mass spectrometry (SIMS), and the degree of contamination caused by Si ions was evaluated in terms of the Si adsorption amount. In the evaluation of the Si adsorption amount, the value when the result of Comparative Example 1 was set to 1.00 was used, and the evaluation was performed based on the following evaluation criteria. The results are shown in Table 3.

[0631] "Evaluation Criteria"

[0632] ◎ (Good): Si adsorption amount is less than 0.70

[0633] O (Good): Si adsorption amount is 0.70 or more and less than 0.90

[0634] Δ (Pass): Si adsorption amount is 0.90 or more and less than 1.10

[0635] X (Fail): Si adsorption amount is 1.10 or more

[0636] (Corrosion resistance test)

[0637] The magnetic recording medium was exposed to a condition at a temperature of 85°C and a relative humidity of 90% for 48 hours. Then, the number of sites where corrosion occurred on the magnetic recording medium was counted using an optical surface analysis device (Candel a 7140 manufactured by KEOI AE TENCOR Co., Ltd.), and the evaluation was performed based on the following evaluation criteria. The results are shown in Table 3.

[0638] "Evaluation Criteria"

[0639] ◎ (excellent): less than 150

[0640] O (good): 150 or more and less than 250

[0641] Δ (pass): 250 or more and less than 1000

[0642] X (fail): 1000 or more

[0643] [Table 3]

[0644]

[0645] As shown in Table 3, the magnetic recording medium of Examples 1 to 25 were evaluated as◎(excellent) or O (good) in all evaluation items. It was thus confirmed that the wear resistance and chemical resistance of the lubricating layer of the magnetic recording medium of Examples 1 to 25 were good, and the effect of suppressing corrosion of the magnetic recording medium was high.

[0646] The wear resistance of the lubricating layer of the magnetic recording medium of Examples 1 to 4, 9, 10, 14 to 18, 20, 22, and 25 using the compounds (A) to (D), (I), (J), (N) to (R), (T), (V), and (Y) was particularly good.

[0647] In the compound group used in the above examples, R 2 is equal to the number of hydroxyl groups contained in R 5 , and in the case where n is 1, a symmetrical structure with R 4 at the center is formed, and in the case where n is 2, a symmetrical structure with R 3’ at the center of the molecule is formed. Therefore, it is easy to uniformly spread on the protective layer, and the coating property becomes good, and thus it is considered that a more excellent wear resistance is obtained.

[0648] Further, the compounds (A) to (D), (I), (J), (N) to (R), (T), (V), and (Y) all have high fluidity because R 1 and R 6 are formula (6-1) or formula (6-2) and have a straight-chain aliphatic amide. Therefore, in the case of the magnetic recording medium of Examples 1 to 4, 9, 10, 14 to 18, 20, 22, and 25, even if a part of the lubricating layer is deformed due to wear and the fluorine-containing ether compound in the lubricating layer moves to another part, the repair force to return to the original position is high. As a result, it is presumed that a particularly excellent wear resistance is obtained.

[0649] In addition, in the case where R 1 and R 6 are formula (6-1) and R 2 is different from R 5The magnetic recording medium of Examples 7, 8, 21 of the compounds (G), (H), (U) in which the total number of hydroxyl groups contained is 3 or more has a good wear resistance compared to the magnetic recording medium of Examples 1 to 4, 9, 10, 14 to 18, 20, 22, 25. It is considered that this is because, in the compounds (A) to (D), (I), (J), (N) to (R), (T), (V), (Y), R 2 and R 5 contain a total number of hydroxyl groups of 2, and thus, compared to the above-mentioned compounds in which the total number is 3 or more, the hydroxyl groups involved in adsorption to the lubricating layer and the protective layer are less, the fluidity of the molecules is high, and thus the above-mentioned repairability becomes high.

[0650] In addition, the magnetic recording medium of Examples 12, 13, 24 of the compounds (L), (M), (X) in which R 1 is formula (6-1) and R 6 is an allyl group or a phenyl group has a good wear resistance. It is considered that this is because, by virtue of the straight-chain aliphatic amide possessed by R 1 , a moderate adhesion to the protective layer is obtained, and, by virtue of R 6 not having an amide bond, fluidity is imparted to the fluorine-containing ether compound.

[0651] In addition, the magnetic recording medium of Examples 5, 6, 19 of the compounds (E), (F), (S) in which R 1 and R 6 are either of formula (6-3) or formula (6-4) has a Si adsorption amount of less than 0.70, a good chemical resistance, and also a good corrosion resistance. It is inferred that this is due to the reasons shown below.

[0652] In the case of the compounds (E), (F), (S), R 1 and R 6 have a relatively rigid aromatic amide, and thus the movement of the molecules is somewhat restricted. Due to this, the lubricating layer using the compounds (E), (F), (S) has a lower ability to hinder the interaction with the protective layer compared to the case where a compound in which R 1 and R 6 have an aliphatic amide is used. 1 and R 6 have an amide, and R 2 and R 5 have a hydroxyl group, and thus the ability of the amide possessed by R 1 and R 6 and the hydroxyl group possessed by R 2 and R 5 to hinder the interaction with each other and the protective layer is extremely low. Thus, it is inferred that the amide possessed by R 1 and R 6 and the hydroxyl group possessed by R 2 and R 5 each easily participate in bonding to the active sites on the protective layer.

[0653] Further, R 1 and R 6 have a planar structure composed of carbon, oxygen and nitrogen having sp 2 hybrid orbitals in a wide range from an aromatic ring to an amide skeleton. It is therefore presumed that the interaction between the aromatic amide of R 1 and R 6 is stronger than the interaction between the aliphatic amide of R 1 and R 6 and the protective layer.

[0654] Further, in the compounds (E), (F), (S), the number of hydroxyl groups contained in R 2 and R 5 is equal, and in the case where n is 1, a symmetrical structure is formed with R 4 as the center, and in the case where n is 2, a symmetrical structure is formed with R 3’ in the center of the molecule. It is therefore considered that it is easy to uniformly spread on the protective layer and the coating property is good.

[0655] As described above, in the magnetic recording medium of Examples 5, 6, 19, the number of polar groups not participating in the bonding of the lubricating layer to the active sites on the protective layer is small, and the interaction between the aromatic amide and the protective layer is moderately strong. It is therefore considered that the polar groups not participating in the bonding of the lubricating layer to the active sites on the protective layer are inhibited from attracting environmental substances that generate contaminant substances, and a particularly good chemical substance resistance is obtained.

[0656] Further, in the magnetic recording medium of Examples 5, 6, 19, since an aromatic ring is introduced in R 1 and R 6 , the hydrophobicity of the lubricating layer containing the fluorine-containing ether compound is good. It is therefore considered that the invasion of water, which is a cause of corrosion of the magnetic recording medium, is effectively inhibited, and a particularly excellent corrosion resistance is obtained.

[0657] In the magnetic recording medium of Examples 9 and 22 using the compounds (I), (V) in which R 2 is formula (2-2) (which is a structure in which one methylene group is added to the skeleton of glycerol (-OCH2CH(OH)CH2O-)), and R 5 is formula (2-4) (which is a structure in which one methylene group is added to the skeleton of glycerol), the corrosion resistance is good.

[0658] Further, in the magnetic recording medium of Examples 9 and 22 using the compounds (I), (V) in which R 4In the magnetic recording medium of Example 20 of the compound (T) of Formula (3-2) and Formula (3-3) which are structures in which one methylene group is added to the skeleton of glycerol, corrosion resistance is good.

[0659] In the compounds (I), (T), (V), R 4 or R 2 and R 5 have a structure in which one methylene group is added to the skeleton of glycerol. Therefore, the hydrophobicity of the lubricating layer containing the fluorine-containing ether compound becomes good, and water which is a cause of corrosion of the magnetic recording medium is effectively prevented from invading. Therefore, it is considered that particularly excellent corrosion resistance is obtained in the magnetic recording media of Examples 9, 20, and 22.

[0660] On the other hand, in the magnetic recording medium of Comparative Example 1 in which the compound (AA) which has a glycerol structure at the center of a chain structure and has a perfluoropolyether chain and a terminal group having two hydroxyl groups sequentially bonded on both sides thereof, respectively, was used, the test results of the abrasion resistance, the chemical resistance, and the corrosion resistance were all "Δ (pass)".

[0661] Further, in the magnetic recording medium of Comparative Example 2 in which the compound (AB) which has an alkyl chain having eight carbon atoms having two hydroxyl groups arranged at the center of a chain structure and has a perfluoropolyether chain and a terminal group having two hydroxyl groups sequentially bonded on both sides thereof, respectively, was used, the test result of the abrasion resistance was "Δ (pass)", and the test results of the chemical resistance and the corrosion resistance were "X (fail)".

[0662] It is considered that this is because, in the magnetic recording media of Comparative Examples 1 and 2, the adhesion of the lubricating layer to the protective layer becomes too strong due to the strong interaction of the hydroxyl groups in the compound (AA) or the compound (AB) with the protective layer, the fluidity of the lubricating layer is impaired, and the abrasion resistance becomes insufficient.

[0663] Further, in the lubricating layer in the magnetic recording media of Comparative Examples 1 and 2, the hydroxyl groups in the compound (AA) or the compound (AB) which do not participate in the bonding to the active sites on the protective layer are many. Therefore, it is considered that Si and / or water are easily mixed between the lubricating layer and the protective layer, and the chemical resistance and the corrosion resistance become insufficient.

[0664] Further, in the magnetic recording medium of Comparative Example 3 in which the compound (AC) which has a skeleton formed of three perfluoropolyether chains connected via an alkyl chain having eight carbon atoms having two hydroxyl groups and has a divalent linking group having one hydroxyl group and a methoxyphenyl group sequentially bonded on both ends thereof, respectively, was used, the test results of the abrasion resistance, the chemical resistance, and the corrosion resistance were all "Δ (pass)".

[0665] In the compound (AC), alkyl chains having 8 carbon atoms and having 2 hydroxyl groups are respectively arranged at both ends of the perfluoropolyether chain arranged at the center of the chain structure. Therefore, the hydrophilicity of the lubricating layer in the magnetic recording medium of Comparative Example 3 is high, and water easily mixes from the lubricating layer. It is considered that as a result, the corrosion resistance becomes insufficient.

[0666] In addition, in the compound (AC), methoxyphenyl groups, which lack adsorbing power, are arranged at both ends of the molecule. Therefore, in the magnetic recording medium of Comparative Example 3, the adhesion of the lubricating layer is insufficient, a gap into which Si can enter easily occurs between the protective layer and the lubricating layer, or the protective layer easily comes off. It is considered that as a result, the chemical resistance and the wear resistance become insufficient.

[0667] In addition, in the magnetic recording medium of Comparative Example 4 in which the compound (AD) in which terminal groups having amide bonds are respectively arranged at both ends of the perfluoropolyether chain arranged at the center of the chain structure via a linking group having a hydroxyl group is used, the test result of the chemical resistance is "Δ (pass)", and the test result of the corrosion resistance is "X (fail)".

[0668] In the compound (AD), no structure including a polar group is arranged at the center of the chain structure. Therefore, in the lubricating layer of the magnetic recording medium of Comparative Example 4, only both ends of the molecule of the compound (AD) are adhered to the protective layer, and the central portion of the chain structure is detached from the protective layer. Therefore, it is inferred that as a result, Si and / or water easily mix between the protective layer and the lubricating layer, and the chemical resistance and the corrosion resistance are worse than in the embodiment.

[0669] Industrial applicability

[0670] By using the lubricant for a magnetic recording medium including the fluorine-containing ether compound of the present application, it is possible to form a lubricating layer that has excellent adhesion even if the thickness is thin, has good chemical resistance and wear resistance, and has a high effect of suppressing corrosion of the magnetic recording medium. The fluorine-containing ether compound described above can be suitably used as a material of a lubricant for a magnetic recording medium.

[0671] Explanation of reference numerals

[0672] 10 • • • magnetic recording medium, 11 • • • substrate, 12 • • • attachment layer, 13 • • • soft magnetic layer, 14 • • • first base layer, 15 • • • second base layer, 16 • • • magnetic layer, 17 • • • protective layer, 18 • • • lubricating layer.

Claims

1. A fluorine-containing ether compound, characterized by, which is represented by the following formula (1), R 1 -R 2 -CH2-R 3 [-CH2-R 4 -CH2-R 3’ ] n -CH2-R 5 -R 6 (1) In formula (1), n is 1 or 2; R 3 and 1 or 2 R 3’ each independently is a perfluoropolyether chain represented by the following formula (4), - (CF2) w1 - (CF2O) w2 - (CF2CF2O) w3 - (CF2CF2CF2O) w4 - (CF2CF2CF2CF2O) w5 - (CF2) w6 - (4) In equation (4), w2, w3, w4, and w5 represent the average degree of polymerization, each independently representing 0 to 20; excluding the case where all w2, w3, w4, and w5 are simultaneously 0; w1 and w6 represent the average quantity of CF2, each independently representing 1 to 3; the order of the repeating units in equation (4) is not particularly restricted; R 3 and 1 or 2 R 3’ The components can be partially or completely the same, or they can all be different; R 4 The linking group is represented by any of the following formulas (3-1) to (3-3). In formula (3-2), r is an integer of 2 to 4, In formula (3-3), s is an integer of 2 to 4; In the case where n is 2, 2 R 4 may be the same or different; R 2 is a linking group represented by the following formula (2-1) or (2-2), and R 2 of the side bonded to R 1 is an oxygen atom; R 5 is a linking group represented by the following formula (2-3) or (2-4), and R 5 of the side bonded to R 6 is an oxygen atom; In formula (2-1), p1 represents an integer of 1 to 3, In formula (2-2), q1 represents an integer of 2 to 4, In formula (2-3), p2 represents an integer of 1 to 3, In formula (2-4), q2 represents an integer of 2 to 4, R 1 and R 6 are terminal groups bonded to the terminal oxygen atom of R 2 or R 5 ; R 1 and R 6 may be the same or different; R 1 and R 6 are any organic group represented by the following formulae (6-1) to (6-12), The dotted line in formulae (6-1) to (6-12) is a bond to R 2 or R 5 in formula (1). In formula (6-1), t represents an integer of 0 to 7, and in formula (6-2), u represents an integer of 0 to 7.

2. The fluorine-containing ether compound according to claim 1, wherein R in the formula (1) is 2 has a total number of 2 to 6 hydroxyl groups. 5 has a total number of 2 to 6 hydroxyl groups.

3. The fluorinated ether compound according to claim 1 or 2, wherein R in formula (1) 3 and 1 or 2 R 3’ All are identical, and R 1 -R 2 -with R 6 -R 5 - They are the same.

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

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

6. A lubricant for magnetic recording media, characterized in that, which comprises the fluorine-containing ether compound according to claim 1 or 2.

7. A magnetic recording medium, characterized by comprising: which is a magnetic recording medium in which at least a magnetic layer, a protective layer, and a lubricating layer are provided in this order on a substrate, the lubricating layer comprises the fluorine-containing ether compound according to claim 1 or 2.

8. The magnetic recording medium according to claim 7, wherein the average film thickness of the lubricating layer is 0.5 nm to 2.0 nm.

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