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

Abstract

A fluorine-containing ether compound represented by formula (1). R < 1 >-R < 2 >-CH < 2 >-R < 3 > [-CH < 2 >-R < 4 >-CH < 2 >-R < 3 >] < x >-CH < 2 >-R < 5 >-R < 6 > (wherein R < 1 > and R < 6 > are organic groups having 1-50 carbon atoms; r2 is a formula (2-1) or (2-2); r5 is represented by formula (2-3) or (2-4); r3 is a perfluoropolyether chain; r4 is represented by formula (3-1) or (3-2); and x is 0-2. > # imgabs0 #

Description

Technical Field

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

[0002] This application claims priority based on Japanese Patent Application No. 2022-083154 filed in Japan on May 20, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] In order to improve the recording density of magnetic recording and reproducing devices, magnetic recording media suitable for high recording density are being developed.

[0004] In the past, as a magnetic recording medium, there is a material that forms a recording layer on a substrate and forms a protective layer of carbon or the like on the recording layer. The protective layer protects the information recorded in the recording layer and improves the sliding property of the magnetic head. However, the durability of the magnetic recording medium cannot be fully obtained by merely arranging a protective layer on the recording layer. Therefore, generally speaking, a lubricant is applied to the surface of the protective layer to form a lubricating layer.

[0005] As a lubricant used when forming a lubricating layer of a magnetic recording medium, for example, a compound containing 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- has been proposed.

[0006] For example, Patent Document 1 discloses a fluorine-containing ether compound in which a divalent linking group including a secondary hydroxyl group and a terminal group are sequentially bonded to both ends of a perfluoropolyether chain via a methylene group (—CH 2 —).

[0007] In addition, Patent Document 2 discloses a fluorinated ether compound in which a glycerol structure (-O-CH2-CH(OH)-CH2-O-) is arranged in the center of a chain structure, and a perfluoropolyether chain, a divalent connecting group containing a secondary hydroxyl group, and an end group having a polar group are sequentially bonded to both sides thereof via methylene groups (-CH2-).

[0008] Patent Document 3 discloses a fluorine-containing ether compound in which a perfluoropolyether chain and a terminal group are sequentially bonded to both sides of a divalent linking group containing a primary hydroxyl group and a secondary hydroxyl group via a methylene group (—CH 2 —).

[0009] In addition, Patent Document 4 discloses a fluorinated ether compound having a skeleton in which three perfluoropolyether chains are connected via a connecting group having a secondary hydroxyl group, and on both sides of the skeleton, a divalent connecting group containing a secondary hydroxyl group and a terminal group having a polar group are connected in sequence via a methylene group (-CH2-).

[0010] Furthermore, in Patent Document 5, a method for producing a polyol (per)fluoropolyether derivative useful as a lubricant for magnetic media is disclosed. In Patent Document 5, it is recorded that a protected triol having two protected hydroxyl functional groups and one free hydroxyl group is reacted with an activator to generate an activated protected triol, which is then subjected to a nucleophilic substitution reaction with a hydroxyl group disposed at the end of a functional (per)fluoropolyether derivative to generate a protected polyol (per)fluoropolyether derivative.

[0011] Prior art literature

[0012] Patent Literature

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

[0014] Patent Document 2: International Publication No. 2021 / 251335

[0015] Patent Document 3: International Publication No. 2021 / 019998

[0016] Patent Document 4: U.S. Patent Application Publication No. 2016 / 0260452

[0017] Patent Document 5: Japanese Patent No. 5334064 Summary of the invention

[0018] Problems to be solved by the invention

[0019] In a magnetic recording and reproducing device, it is required to further reduce the flying height of the magnetic head. Therefore, it is required to further reduce the thickness of the lubricating layer in the magnetic recording medium.

[0020] However, generally speaking, if the thickness of the lubricating layer is thin, the chemical resistance of the magnetic recording medium tends to decrease. In addition, if the floating amount of the magnetic head is small, the fluorine-containing ether compound in the lubricating layer sometimes adheres to the pickup of the magnetic head.

[0021] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluorine-containing ether compound which can form a lubricating layer having excellent chemical resistance and capable of suppressing pickup and can be suitably used as a material for a lubricant for a magnetic recording medium.

[0022] Another object of the present invention is to provide a lubricant for a magnetic recording medium which can form a lubricating layer comprising the fluorinated ether compound of the present invention and having excellent chemical resistance and a high pickup suppression effect.

[0023] Another object of the present invention is to provide a magnetic recording medium having a lubricating layer containing the fluorinated ether compound of the present invention and having excellent chemical resistance and a good pickup suppression effect.

[0024] Means for solving problems

[0025] The present invention includes the following aspects.

[0026] A first aspect of the present invention provides the following fluorine-containing ether compound.

[0027] [1] A fluorine-containing ether compound characterized by being represented by the following formula (1).

[0028] R 1 -R 2 -CH2-R 3 [-CH2-R 4 -CH2-R 3 ] x -CH2-R 5 -R 6 (1)

[0029] (In formula (1), R 1 and R 6 Each independently represents an organic group having 1 to 50 carbon atoms; R 2 is a divalent linking group represented by the following formula (2-1) or (2-2); R 5 is a divalent linking group represented by the following formula (2-3) or (2-4); x represents an integer of 0 to 2; R 3 is a perfluoropolyether chain; when x is 1 or 2, 2 or 3 R 3 They may be partly or completely the same, or they may be different; R 4 is a divalent linking group represented by the following formula (3-1) or formula (3-2); when x is 2, two R 4 They can be the same or different.)

[0030]

[0031] (In formula (2-1), n1 represents an integer of 2 to 4; in formula (2-1), the dotted line bonded to the carbon atom represents the bond with R 1 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0032] (In formula (2-2), the dotted line bonded to the carbon atom represents the bond with R 1 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0033] (In formula (2-3), n2 represents an integer of 2 to 4; in formula (2-3), the dotted line bonded to the carbon atom represents the bond with R 6 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0034] (In formula (2-4), the dotted line bonded to the carbon atom represents the bond with R 6 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0035] (In formula (3-1), n3 represents an integer of 2 to 4; y1 represents an integer of 1 to 3; y2 represents an integer of 1 to 3; at least one of y1 and y2 is 1; the dotted line bonded to the oxygen atom on the left represents the bond to R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 6 The side methylene bond is bonded to the bond.)

[0036] (In formula (3-2), y3 represents an integer of 1 to 3; y4 represents an integer of 1 to 3; at least one of y3 and y4 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 6 The side methylene bond is bonded to the bond.)

[0037] The fluorine-containing ether compound according to the first aspect of the present invention preferably has the features described in the following [2] to

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

[10] are combined.

[0038] [2] The fluorinated ether compound according to [1], wherein R in the above formula (1) 2 is the above formula (2-1), R 5 For the above formula (2-3), x R 4 All of them are the above formula (3-1), y1 in the above formula (3-1) is 1, and y2 is 1.

[0039] [3] The fluorinated ether compound according to [2], wherein n1 in the formula (2-1), n2 in the formula (2-3), and n3 in the formula (3-1) are all the same value.

[0040] [4] The fluorinated ether compound according to [1], wherein R in the above formula (1) 2 is the above formula (2-2), R 5 For the above formula (2-4), x R 4 All of them are the above formula (3-2), y3 in the above formula (3-2) is 1, and y4 is 1.

[0041] [5] The fluorinated ether compound according to any one of [1] to [4], wherein R in the formula (1) 1 and R 6are each independently any one of an organic group having a polar group, an organic group having a carbon-carbon unsaturated bond, and an organic group having both a polar group and a carbon-carbon unsaturated bond,

[0042] The polar group is at least one selected from the group consisting of a hydroxyl group, an amino group, a carboxyl group, a formyl group, a carbonyl group, a sulfonyl group, a cyano group, and a group having an amide bond,

[0043] The carbon-carbon unsaturated bond is at least one selected from an aromatic hydrocarbon group, an unsaturated heterocyclic group, an alkenyl group, and an alkynyl group which may have a substituent.

[0044] [6] The fluorinated ether compound according to any one of [1] to [5], wherein R in the formula (1) 1 and R 6 The total number of polar groups contained is 1-4.

[0045] [7] The fluorinated ether compound according to any one of [1] to [6], wherein R in the formula (1) 1 -R 2 -With R 6 -R 5 -same.

[0046] [8] The fluorinated ether compound according to any one of [1] to [7], wherein the (x+1)th R in the formula (1) 3 Each is independently a perfluoropolyether chain represented by the following formula (4).

[0047] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0048] (In formula (4), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein w2, w3, w4, and w5 are not all 0 at the same time; w1 and w6 represent average values ​​of the number of CF2, and each independently represents 1 to 3; there is no particular restriction on the arrangement order of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) as repeating units in formula (4).)

[0049] [9] The fluorinated ether compound according to any one of [1] to [7], wherein the (x+1)th R in the formula (1) 3Each independently represents any one selected from the group consisting of perfluoropolyether chains represented by the following formula (4-1) to formula (4-4).

[0050] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1)

[0051] (In formula (4-1), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0052] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2)

[0053] (In formula (4-2), j represents an average degree of polymerization and is 1 to 15.)

[0054] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3)

[0055] (In formula (4-3), k represents an average degree of polymerization and is 1 to 10.)

[0056] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4)

[0057] (In formula (4-4), w8 and w9 represent the average degree of polymerization and are each independently 1 to 20; w7 and w10 represent the average value of the number of CF2 and are each independently 1 to 2.)

[0058]

[10] The fluorinated ether compound according to any one of [1] to [9], wherein the number average molecular weight is within the range of 500 to 10,000.

[0059] A second aspect of the present invention provides the following lubricant for a magnetic recording medium.

[0060]

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

[10] .

[0061] A third aspect of the present invention provides the following magnetic recording medium.

[0062]

[12] A magnetic recording medium, characterized in that at least a magnetic layer, a protective layer, and a lubricating layer are provided in this order on a substrate,

[0063] The lubricating layer contains the fluorine-containing ether compound described in any one of [1] to

[10] .

[0064] The magnetic recording medium according to the third aspect of the present invention preferably has the features described in the following

[13] .

[0065]

[13] The magnetic recording medium according to

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

[0066] Effects of the Invention

[0067] The fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is suitable as a material for a lubricant for a magnetic recording medium.

[0068] Since the lubricant for a magnetic recording medium of the present invention contains the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer having excellent chemical resistance and a high pickup suppression effect.

[0069] The magnetic recording medium of the present invention has a lubricating layer comprising a fluorinated ether compound of the present invention. Therefore, the magnetic recording medium of the present invention has good chemical resistance, good pickup suppression effect, and excellent reliability and durability. In addition, the lubricating layer possessed by the magnetic recording medium of the present invention can suppress pickup due to good chemical resistance, so the thickness can be made thin, and the floating amount of the magnetic head can be made small. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention. DETAILED DESCRIPTION

[0071] The present inventors have conducted intensive studies as described below in order to solve the above-mentioned problems.

[0072] In the past, as the material of the magnetic recording medium lubricant (hereinafter, sometimes abbreviated as "lubricant") coated on the surface of the protective layer, it is preferred to use a fluorinated ether compound with a polar group such as a hydroxyl group. The polar group contained in the fluorinated ether compound combines with the active point on the protective layer to improve the adhesion of the lubricating layer to the protective layer. For the fluorinated ether compound in the past, the terminal in the chain structure is configured with a polar group. In addition, when the fluorinated ether compound has a plurality of perfluoropolyether chains, a polar group is configured between adjacent perfluoropolyether chains.

[0073] However, when a thin lubricating layer is formed on a protective layer using a conventional lubricant, it is difficult to realize a lubricating layer having good chemical resistance and a high pickup suppression effect.

[0074] The reason for this is that the fluorine-containing ether compound contained in the lubricating layer contains polar groups which are not adsorbed to active sites present in large numbers on the protective layer.

[0075] If there is a polar group of the active point not adsorbed on the protective layer in the fluorinated ether compound included in the lubricating layer, it is easy to introduce pollutants near the polar group, and the chemical resistance of the lubricating layer is reduced. In addition, sometimes the polar group in the fluorinated ether compound not adsorbed on the active point on the protective layer is adsorbed on the magnetic head, and the fluorinated ether compound is picked up by the magnetic head with it as the starting point. According to these circumstances, when there is a polar group of the active point not adsorbed on the protective layer in the fluorinated ether compound included in the lubricating layer, the chemical resistance and pickup inhibition effect of the lubricating layer are easy to become insufficient.

[0076] Therefore, the present inventors focused on the bonding behavior between the polar groups contained in the fluorinated ether compound and the active sites on the protective layer and conducted intensive studies to realize a fluorinated ether compound that is less likely to generate polar groups that do not participate in bonding with the active sites on the protective layer.

[0077] As a result, the present inventors have found that secondary hydroxyl groups contained in divalent linking groups disposed between adjacent perfluoropolyether chains and between a perfluoropolyether chain and a terminal group among polar groups contained in a fluorinated ether compound are less likely to participate in bonding with active sites on a protective layer.

[0078] Therefore, the inventors chemically modified the secondary hydroxyl groups contained in the divalent connecting groups disposed between adjacent perfluoropolyether chains and between the perfluoropolyether chains and the terminal groups of the fluorinated ether compound and converted them into primary hydroxyl groups. Furthermore, the converted fluorinated ether compound was used to form a lubricating layer. As a result, it was found that the chemical resistance and the pickup suppression effect were improved. It is presumed that this is because the fluorinated ether compound is not easy to generate hydroxyl groups that are not bound to the active points present on the protective layer.

[0079] Furthermore, the inventors have repeatedly conducted in-depth studies and found that the fluorine-containing ether compound can be used as long as a specific divalent terminal connecting group having only one primary hydroxyl group is configured between the perfluoropolyether chain and the terminal group, and further, in the case of having two or three perfluoropolyether chains, a specific divalent intermediate connecting group having only one primary hydroxyl group is configured between adjacent perfluoropolyether chains. The two terminal connecting groups (in the case of having multiple perfluoropolyether chains, the two terminal connecting groups and the one or two intermediate connecting groups) each have a side chain part that branches from the chain structure of the fluorine-containing ether compound and performs an ether bond. The side chain part has a primary hydroxyl group configured at the front end, and has a connecting group containing a methylene group (-CH2-) that connects the carbon atom bonded to the primary hydroxyl group and the oxygen atom bonded to the carbon atom of the chain structure.

[0080] Such a fluorinated ether compound is unlikely to generate a polar group that does not bind to a functional group (active site) present on the protective layer for the reasons described below. Therefore, it is estimated that the fluorinated ether compound can form a lubricating layer having excellent chemical resistance and a good pickup suppression effect.

[0081] That is, the above two terminal connecting groups (in the case of having multiple perfluoropolyether chains, the above two terminal connecting groups and one or two intermediate connecting groups) each have only one primary hydroxyl group, which is sterically empty compared to the case of having secondary hydroxyl groups instead of primary hydroxyl groups. Therefore, the primary hydroxyl groups possessed by the above two terminal connecting groups (or, the above two terminal connecting groups and one or two intermediate connecting groups) are not easily hindered from binding to the active points on the protective layer by the bulky parts of the fluorine-containing ether compound such as the adjacent perfluoropolyether chain and the tertiary carbon to which the side chain of each terminal connecting group (or, the above two terminal connecting groups and one or two intermediate connecting groups) is bonded. Moreover, the primary hydroxyl group is generally freer to move than the secondary hydroxyl group. Therefore, the primary hydroxyl groups possessed by the above two terminal connecting groups (or, the above two terminal connecting groups and one or two intermediate connecting groups) can each move spontaneously relative to the active points on the protective layer. According to these conditions, the primary hydroxyl groups possessed by the two terminal connecting groups (or the two terminal connecting groups and one or two intermediate connecting groups) can easily form a bond with an active site on the protective layer.

[0082] Further, for the above-mentioned fluorinated ether compound, terminal connecting groups are respectively arranged between the two terminal groups and the perfluoropolyether chain. Therefore, the distance between the primary hydroxyl group possessed by the terminal connecting group arranged at one end side of the chain structure and the primary hydroxyl group possessed by the terminal connecting group arranged at the other end side of the chain structure will not become too close. In addition, in the case where the above-mentioned fluorinated ether compound has multiple perfluoropolyether chains, perfluoropolyether chains are respectively arranged between the above-mentioned terminal connecting groups and 1 or 2 intermediate connecting groups. Therefore, the distance between the primary hydroxyl group possessed by each terminal connecting group and the primary hydroxyl group possessed by 1 or 2 intermediate connecting groups will not become too close. Further, in the case where the above-mentioned fluorinated ether compound has 3 perfluoropolyether chains, there are 2 intermediate connecting groups. In this case, since the perfluoropolyether chain is arranged between adjacent intermediate connecting groups, the distance between the primary hydroxyl groups possessed by each of the adjacent intermediate connecting groups will not become too close.

[0083] Therefore, for the above-mentioned fluorinated ether compound, the primary hydroxyl groups of the above-mentioned two terminal connecting groups (in the case of having multiple perfluoropolyether chains, the above-mentioned two terminal connecting groups and one or two intermediate connecting groups) are not easily hindered from binding to the active points on the protective layer by the primary hydroxyl groups of other terminal connecting groups (or, other terminal connecting groups and intermediate connecting groups) contained in the fluorinated ether compound. In addition, for the above-mentioned fluorinated ether compound, the distance between the primary hydroxyl groups of the two terminal connecting groups (or, the distance between the primary hydroxyl groups of each terminal connecting group, the distance between the primary hydroxyl groups of each terminal connecting group and the primary hydroxyl groups of one or two intermediate connecting groups, and the distance between the primary hydroxyl groups of each adjacent intermediate connecting group) will not become too close. Therefore, the primary hydroxyl groups of the above-mentioned two terminal connecting groups (or, the above-mentioned terminal connecting group and one or two intermediate connecting groups) are not easily agglomerated with each other.

[0084] Furthermore, for the above-mentioned fluorine-containing ether compound, the above-mentioned two terminal connecting groups (or, the above-mentioned two terminal connecting groups and one or two intermediate connecting groups) have a side chain part that has only one primary hydroxyl group and branches from the chain structure of the fluorine-containing ether compound to form an ether bond. For the above-mentioned fluorine-containing ether compound, since the side chain part of the two terminal connecting groups (or, the above-mentioned two terminal connecting groups and one or two intermediate connecting groups) branches from the chain structure to form an ether bond, the flexibility of the side chain part is better than the case where the side chain part is directly bonded to the chain structure (bonded through a carbon-carbon bond). Therefore, the primary hydroxyl group of the side chain part of the above-mentioned two terminal connecting groups (or, the above-mentioned two terminal connecting groups and one or two intermediate connecting groups) can easily form a bond with the active point on the protective layer.

[0085] Further, for the above-mentioned fluorine-containing ether compound, in the side chain portion possessed by the above-mentioned two terminal connecting groups (or, the above-mentioned two terminal connecting groups and one or two intermediate connecting groups), the carbon atom bound to the primary hydroxyl group arranged at the front end and the oxygen atom bound to the carbon atom of the chain structure are bound by a connecting group containing a methylene group (-CH2-). Therefore, even in the case where the terminal group contains a polar group, the distance between the polar group possessed by the terminal group and the primary hydroxyl group possessed by the terminal connecting group adjacent to the terminal group becomes appropriate. As a result, the primary hydroxyl group possessed by the terminal connecting group is not easily hindered from binding to the active point on the protective layer due to the polar group possessed by the terminal group. In addition, since the distance between the primary hydroxyl group possessed by the terminal connecting group and the polar group possessed by the terminal group is appropriate, even in the case where the terminal group contains a polar group, the primary hydroxyl group possessed by the terminal connecting group adjacent to the terminal group and the polar group possessed by the terminal group are not easy to agglomerate.

[0086] As described above, in the above-mentioned fluorine-containing ether compound, the side chain part possessed by the above-mentioned two terminal connecting groups (or, the above-mentioned two terminal connecting groups and one or two intermediate connecting groups) has good flexibility, and the primary hydroxyl groups possessed by the side chain part can move spontaneously, respectively, and are not easy to agglomerate, and are not easy to be hindered from binding with the active points on the protective layer by the primary hydroxyl groups possessed by other terminal connecting groups (or, other terminal connecting groups and intermediate connecting groups), polar groups possessed by the terminal groups, and large-volume parts in the fluorine-containing ether compound. According to these circumstances, for the above-mentioned fluorine-containing ether compound, it is not easy to produce polar groups that are not bound to the functional groups (active points) present on the protective layer. As a result, it is inferred that the above-mentioned fluorine-containing ether compound can form a lubricating layer that is not easy to introduce pollutants, has good resistance to chemical substances, is not easy to be picked up by the magnetic head, and has a good pickup suppression effect.

[0087] Furthermore, the present inventors have confirmed that a lubricating layer having excellent chemical resistance and a high pickup suppression effect can be formed by using a lubricant containing the above-mentioned fluorinated ether compound, and thus have conceived the present invention.

[0088] Below, the preferred example of fluorine-containing ether compound of the present invention, magnetic recording medium lubricant and magnetic recording medium is described in detail. In addition, the present invention is not limited only to the embodiment shown below. The present invention can add, omit, replace, change number, amount, position, ratio, material, formation etc. within the scope not exceeding the purpose of the present invention.

[0089] [Fluorinated ether compounds]

[0090] The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

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

[0092] (In formula (1), R 1 and R 6 Each independently represents an organic group having 1 to 50 carbon atoms; R 2 is a divalent linking group represented by the following formula (2-1) or (2-2); R 5 is a divalent linking group represented by the following formula (2-3) or (2-4); x represents an integer of 0 to 2; R 3 is a perfluoropolyether chain; when x is 1 or 2, 2 or 3 R 3 They may be partly or completely the same, or they may be different; R4 is a divalent linking group represented by the following formula (3-1) or formula (3-2); when x is 2, two R 4 They can be the same or different.)

[0093]

[0094] (In formula (2-1), n1 represents an integer of 2 to 4; in formula (2-1), the dotted line bonded to the carbon atom represents the bond with R 1 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0095] (In formula (2-2), the dotted line bonded to the carbon atom represents the bond with R 1 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0096]

[0097] (In formula (2-3), n2 represents an integer of 2 to 4; in formula (2-3), the dotted line bonded to the carbon atom represents the bond with R 6 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0098] (In formula (2-4), the dotted line bonded to the carbon atom represents the bond with R 6 The dotted line that is connected to the oxygen atom represents the bond that is connected to the methylene group.)

[0099]

[0100] (In formula (3-1), n3 represents an integer of 2 to 4; y1 represents an integer of 1 to 3; y2 represents an integer of 1 to 3; at least one of y1 and y2 is 1; the dotted line bonded to the oxygen atom on the left represents the bond to R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 6 The side methylene bond is bonded to the bond.)

[0101] (In formula (3-2), y3 represents an integer of 1 to 3; y4 represents an integer of 1 to 3; at least one of y3 and y4 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 6 The side methylene bond is bonded to the bond.)

[0102] The fluorinated ether compound of this embodiment has R having only one primary hydroxyl group as shown in formula (1). 2The divalent terminal linking group, R 3 1 to 3 perfluoropolyether chains (hereinafter sometimes referred to as PFPE chains) shown, 0 to 2 R having only one primary hydroxyl group 4 The divalent intermediate linking group shown in FIG. 1 and R having only one primary hydroxyl group 5 The backbone of the chain structure is formed by connecting the divalent terminal connecting groups shown in FIG. 1 and R 6 The terminal group is formed of an organic group having 1 to 50 carbon atoms as shown.

[0103] In the fluorinated ether compound represented by formula (1), x represents an integer of 0 to 2. Since x is 2 or less in the fluorinated ether compound represented by formula (1), the molecule does not become too large. Therefore, it becomes a fluorinated ether compound that can move freely on the protective layer, easily wet and spread on the protective layer, and easily obtain a lubricating layer with a uniform film thickness. In addition, in order to form a fluorinated ether compound that can form a lubricating layer with better chemical resistance and better pickup suppression effect, x is preferably 1 or 2.

[0104] (R 2 and R 5 The divalent terminal linking group shown has only one primary hydroxyl group)

[0105] In the fluorine-containing ether compound represented by formula (1), R 2 and R 5 is a divalent terminal connecting group having only one primary hydroxyl group. 2 and R 5 Each has no secondary hydroxyl group and only has one primary hydroxyl group. 2 and R 5 Compared with the case where each has a secondary hydroxyl group, R 2 and R 5 The contained hydroxyl groups are easy to interact with the active points on the protective layer. Therefore, when a lubricating layer is formed on the protective layer using a lubricant containing a fluorinated ether compound represented by formula (1), a suitable interaction occurs between the lubricating layer and the protective layer. Therefore, the fluorinated ether compound represented by formula (1) can form a lubricating layer having excellent chemical resistance and a good pickup suppression effect.

[0106] R 2 is a divalent linking group represented by formula (2-1) or formula (2-2). 2 R 3 The end of the side is an oxygen atom. 2 R 3 The end of the side is connected to R through an ether bond 3 Combined methylene bond.2 R 1 The end of the side is a carbon atom. 2 R 1 The end of the side with R 1 Combine.

[0107] R 2 The main chain portion having a chain structure forming a fluorine-containing ether compound and a 2 R 1 The side chain part is a side chain part that branches from the main chain part and is ether-bonded to the carbon atom at the terminal of the side. The side chain part has a primary hydroxyl group at the front end, and has a linking group containing a methylene group (-CH2-) that connects the carbon atom to which the primary hydroxyl group is bonded to an oxygen atom (etheric oxygen atom) bonded to a carbon atom of the main chain part.

[0108] In the configuration in R 2 R 1 On the terminal carbon atom of the side, through R 2 The ether bond contained in the formula (2-1) is combined with -(CH2) n1 OH or -CH2CH2OCH2CH2OH in formula (2-2) as a side chain. 2 The side chain part is configured in R 2 R 1 The terminal carbon atom of the side is ether-bonded to R 2 The side chain part is configured in R 2 R 1 Compared with the case where the terminal carbon atom of the side is directly bonded (bonded via a carbon-carbon bond), R 2 The side chain portion of R has good flexibility. 2 The side chain portion of R has a chain structure of appropriate length including a linking group. 2 The side chain portion is easy to interact with the active sites on the protective layer.

[0109] In formula (2-1), n1 is an integer of 2 to 4. If n1 is 2 or more, R 2 The primary hydroxyl groups contained in the PFPE chain in the fluorinated ether compound are arranged in R 2 R 1 The distance between bulky parts such as tertiary carbon at the end of the side is sufficiently far, and R 2 The contained primary hydroxyl groups can move freely. If n1 is 4 or less, -(CH2) in formula (2-1) is maintained. n1 OH's softness. For -(CH2) n1 OH can move flexibly, and n1 is preferably 2 to 3, and most preferably 2.

[0110] In the formula (2-2), -CH2CH2OCH2CH2OH contains an ether bond (-O-). Therefore, -CH2CH2OCH2CH2OH in the formula (2-2) maintains flexibility in movement.

[0111] R 5 is a divalent linking group represented by formula (2-3) or formula (2-4). 5 R 3 The end of the side is an oxygen atom. 5 R 3 The end of the side is connected to R through an ether bond 3 Combined methylene bond. 5 R 6 The end of the side is a carbon atom. 5 R 6 The end of the side with R 6 Combine.

[0112] R 5 The main chain portion having a chain structure forming a fluorine-containing ether compound and a 5 R 6 A side chain portion that branches from the main chain portion and is ether-bonded to the carbon atom at the terminal of the side. 2 Similarly, the side chain portion has a primary hydroxyl group at the front end and has a linking group containing a methylene group (-CH2-) that connects the carbon atom bonded to the primary hydroxyl group and the oxygen atom (etheric oxygen atom) bonded to the carbon atom of the main chain portion.

[0113] In the configuration in R 5 R 6 On the terminal carbon atom of the side, through R 5 The ether bond contained in the formula (2-3) is combined with -(CH2) n2 OH or -CH2CH2OCH2CH2OH in formula (2-4) as a side chain. 5 The side chain part is configured in R 5 R 6 The terminal carbon atom of the side is ether-bonded to R 5 The side chain part is configured in R 5 R 6 Compared with the case where the terminal carbon atom of the side is directly bonded (bonded via a carbon-carbon bond), R 5 The side chain portion of R has good flexibility. 5 The side chain portion of R has a chain structure of appropriate length including a linking group. 5 The side chain portion is easy to interact with the active sites on the protective layer.

[0114] In formula (2-3), n2 is an integer of 2 to 4. If n2 is 2 or more, R 5 The primary hydroxyl groups contained in the PFPE chain in the fluorinated ether compound are arranged in R 5 R 6 The distance between bulky parts such as tertiary carbon at the end of the side is sufficiently far, and R 5 The contained primary hydroxyl groups can move freely. If n2 is 4 or less, -(CH2) in formula (2-3) is maintained. n1 OH's softness. For -(CH2) n2 OH can move flexibly, and n2 is preferably 2 to 3, and most preferably 2.

[0115] In the formula (2-4), -CH2CH2OCH2CH2OH contains an ether bond (-O-). Therefore, -CH2CH2OCH2CH2OH in the formula (2-4) maintains flexibility in movement.

[0116] R 2 and R 5 They can be the same or different. 2 With R 5 If the above two compounds are the same, it becomes a fluorine-containing ether compound which is easy to produce and is preferred.

[0117] In this manual, the term “R 2 With R 5 "same" means that relative to the -CH2-R arranged at the center of the fluorinated ether compound represented by formula (1), 3 [-CH2-R 4 -CH2-R 3 ] x -CH2-, R 2 The atoms contained in R 5 The atoms involved have a symmetric configuration.

[0118] That is, the fluorine-containing ether compound represented by formula (1) is preferably 2 is formula (2-1) and R 5 A fluorine-containing ether compound of formula (2-3) wherein n1 in formula (2-1) is the same as n2 in formula (2-3), or R 2 Formula (2-2), and R 5 It is a fluorine-containing ether compound of formula (2-4).

[0119] (R 4 The divalent intermediate linker shown has only one primary hydroxyl group)

[0120] In the fluorine-containing ether compound represented by formula (1), when x is 1 or 2, R 3Each PFPE chain shown is connected via -CH2-R 4 -CH2- and bond to each other. When x is 1 or 2, x R 4 is a divalent intermediate linking group having only one primary hydroxyl group. 4 Each has no secondary hydroxyl group, but only one primary hydroxyl group. 4 Compared with the case where each has a secondary hydroxyl group, R 4 The contained hydroxyl groups are easy to interact with the active points on the protective layer. Therefore, when a lubricating layer is formed on the protective layer using a lubricant containing a fluorinated ether compound represented by formula (1), a suitable interaction occurs between the lubricating layer and the protective layer. Therefore, the fluorinated ether compound represented by formula (1) can form a lubricating layer having excellent chemical resistance and a good pickup suppression effect.

[0121] R 4 is a divalent linking group represented by formula (3-1) or formula (3-2). 4 The ends of both sides of R are oxygen atoms. 4 The two ends of the 3 Combined methylene bond.

[0122] R 4 The main chain part having a chain structure forming a fluorine-containing ether compound and the 4 The side chain part is a side chain part that branches from the main chain part to carbon atoms to which the terminal oxygen atoms on both sides are bonded via 1 to 3 methylene groups to form an ether bond. The side chain part has a primary hydroxyl group at the front end and has a linking group containing a methylene group (-CH2-) that bonds the carbon atom to which the primary hydroxyl group is bonded to an oxygen atom (etheric oxygen atom) bonded to a carbon atom of the main chain part.

[0123] In R 4 The two oxygen atoms at the ends of both sides of are bonded to the carbon atom via 1 to 3 methylene groups, and -(CH2) in the formula (3-1) is bonded via an ether bond. n3 OH or -CH2CH2OCH2CH2OH in formula (3-2) as a side chain. 4 The side chain part forms R 4 The carbon atom of the main chain of 4 The side chain part forms R 4 Compared with the case where the carbon atoms of the main chain of 4 The side chain portion of R has good flexibility. 4The side chain portion of R has a chain structure of appropriate length including a linking group. 4 The side chain portion is easy to interact with the active sites on the protective layer.

[0124] In formula (3-1), n3 is an integer of 2 to 4. If n3 is 2 or more, R 4 The primary hydroxyl groups contained in the PFPE chain in the fluorinated ether compound form R 4 The carbon atoms of the main chain part and R 4 The distance between the bulky sites such as the tertiary carbon to which the side chain of the ether bond is connected is sufficiently far, and R 4 The contained primary hydroxyl groups can move freely. If n3 is 4 or less, -(CH2) in formula (3-1) is maintained. n3 OH's softness. For -(CH2) n3 OH can move flexibly, and n3 is preferably 2 to 3, and most preferably 2.

[0125] In formula (3-1), y1 is an integer of 1 to 3, and y2 is an integer of 1 to 3. At least one of y1 and y2 is 1. Since at least one of y1 and y2 is 1, it becomes a fluorine-containing ether compound that is easy to manufacture. In order to maintain the overall flexibility of the divalent linking group represented by formula (3-1), y2 when only y1 is 1 (or y1 when only y2 is 1) among y1 and y2 is 3 or less, preferably 2 or less. In order to maintain the overall flexibility of the divalent linking group represented by formula (3-1), y1 and y2 are more preferably y1 is 1 and y2 is 1.

[0126] In the formula (3-2), -CH2CH2OCH2CH2OH contains an ether bond (-O-). Therefore, -CH2CH2OCH2CH2OH in the formula (3-2) maintains flexibility in movement.

[0127] In formula (3-2), y3 is an integer of 1 to 3, and y4 is an integer of 1 to 3. At least one of y3 and y4 is 1. Since at least one of y3 and y4 is 1, it becomes a fluorine-containing ether compound that is easy to manufacture. In order to maintain the overall flexibility of the divalent linking group shown in formula (3-2), among y3 and y4, when only y3 is 1, y4 (or y3 when only y4 is 1) is 3 or less, preferably 2 or less. In order to maintain the overall flexibility of the divalent linking group shown in formula (3-2), y3 and y4 are more preferably y3 is 1 and y4 is 1.

[0128] In formula (1), when x is 2, the two R 4 They can be the same or different. 4Under the same conditions, it is preferred to be a fluorine-containing ether compound that is easy to manufacture. 4 Same” means two R 4 The atoms contained in the R 3 That is, when x is 2, the fluorine-containing ether compound represented by formula (1) preferably has two R 4 Formula (3-1), 2 R 4 The n3 in formula (3-1) is the same, and the two R 4 In the formula (3-1), y1 and y2 are relative to R arranged in the center of the chain structure. 3 The fluorinated ether compound with symmetrical values ​​or two R 4 is formula (3-2), and 2 R 4 In the formula (3-2), y3 and y4 are relative to R arranged in the center of the chain structure. 3 The fluorine-containing ether compound has a symmetrical value. 1 Side R 4 It is represented by formula (3-1), where y1 is 1, y2 is 2, and R 6 Side R 4 As shown in formula (3-1), when y1 in formula (3-1) is 2, y2 is 1, and the value of n3 in all formulas (3-1) is the same, the two R 4 In addition, for example, in R 1 Side R 4 It is represented by formula (3-2), where y3 is 1, y4 is 2, and R 6 Side R 4 It is represented by formula (3-2). When y3 is 2 and y4 is 1 in formula (3-2), two R 4 same.

[0129] Among the fluorine-containing ether compounds represented by formula (1), R 2 Formula (2-1), R 5 Formula (2-3), x R 4 All are formula (3-1). In this case, it is more preferred that y1 in formula (3-1) is 1, and y2 is 1. Further, it is more preferred that n1 in formula (2-1), n2 in formula (2-3), and n3 in formula (3-1) are all the same. The reason is that it becomes a fluorine-containing ether compound that can be easily and efficiently manufactured.

[0130] Among the fluorine-containing ether compounds represented by formula (1), R 2 Formula (2-2), R 5 Formula (2-4), x R 4All of them are formula (3-2). The reason is that it is a fluorine-containing ether compound that can be easily and efficiently produced. 2 Formula (2-2), R 5 Formula (2-4), x R 4 When all of them are represented by the formula (3-2), it is more preferable that y3 is 1 and y4 is 1 in the formula (3-2).

[0131] (R 3 PFPE chain shown)

[0132] In the fluorine-containing ether compound represented by formula (1), (x+1) R 3 Each independently represents a perfluoropolyether chain. When a lubricant comprising the fluorinated ether compound of this embodiment is applied onto the protective layer to form a lubricating layer, R 3 The PFPE chains shown cover the surface of the protective layer and impart lubricity to the lubricating layer, thereby reducing the friction between the magnetic head and the protective layer. 3 The PFPE chain shown is appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, etc.

[0133] In the fluorine-containing ether compound represented by formula (1), when x is 1 or 2, 2 or 3 R 3 Some or all of them may be the same, or they may be different. (x+1) R 3 It is preferred that all of them are the same. This is because the coating state of the protective layer becomes uniform due to the fluorine-containing ether compound, thereby forming a lubricating layer with better adhesion. 3 Two or more R 3 The same means (x+1) R 3 Among them, the repeating units containing two or more PFPE chains have the same structure as R 3 . In the same R 3 The same repeating unit structure and different average polymerization degree R 3 .

[0134] As R 3 The PFPE chain shown in the figure may be a PFPE chain formed by a polymer or copolymer of a perfluoroalkylene oxide compound, etc. Examples of the perfluoroalkylene oxide compound include perfluoromethylene oxide compounds, perfluoroethylene oxide compounds, perfluoro-n-propylene oxide compounds, perfluoro-isopropylene oxide compounds, and perfluorobutylene oxide compounds.

[0135] The (x+1) R in formula (1) 3 Preferably, each of the PFPE chains independently is a polymer or copolymer derived from a perfluoroalkylene oxide compound and represented by the following formula (4).

[0136] -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4)

[0137] (In formula (4), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein w2, w3, w4, and w5 are not all 0 at the same time; w1 and w6 represent average values ​​of the number of CF2, and each independently represents 1 to 3; there is no particular restriction on the arrangement order of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) as repeating units in formula (4).)

[0138] In formula (4), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20, preferably 0 to 15, and more preferably 0 to 10. They may be 1 to 8, 2 to 6, 3 to 5, and the like.

[0139] In formula (4), w1 and w6 are average values ​​representing the number of CF2, and each independently represents 1 to 3. In the PFPE chain represented by formula (4), w1 and w6 are determined by the structure of the repeating unit arranged at the end of the chain structure, etc.

[0140] In formula (4), (CF2O), (CF2CF2CF2O), (CF2CF2CF2O), (CF2CF2CF2CF2O) are repeating units. There is no particular restriction on the arrangement order of the repeating units in formula (4). In addition, there is no particular restriction on the number of types of repeating units in formula (4).

[0141] The (x+1) R in formula (1) 3 Preferably, each independently is any one selected from the group consisting of PFPE chains represented by the following formula (4-1) to formula (4-4).

[0142] If (x+1) R 3 Each independently represents any one of the PFPE chains represented by formula (4-1) to (4-4), and thus a lubricating layer having good lubricity can be obtained. 3When each is independently selected from any one of the PFPE chains represented by formula (4-1) to formula (4-4), the ratio of the number of oxygen atoms (the number of ether bonds (-O-)) in the PFPE chain to the number of carbon atoms is appropriate. Therefore, a fluorinated ether compound having a moderate hardness is obtained. Therefore, the fluorinated ether compound applied to the protective layer is not easily agglomerated on the protective layer, and a thinner lubricating layer can be formed with a sufficient coverage. In addition, the fluorinated ether compound has moderate softness, so that a lubricating layer with better chemical resistance can be formed.

[0143] -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1)

[0144] (In formula (4-1), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0145] -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2)

[0146] (In formula (4-2), j represents an average degree of polymerization and is 1 to 15.)

[0147] -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3)

[0148] (In formula (4-3), k represents an average degree of polymerization and is 1 to 10.)

[0149] -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4)

[0150] (In formula (4-4), w8 and w9 represent the average degree of polymerization and are each independently 1 to 20; w7 and w10 represent the average value of the number of CF2 and are each independently 1 to 2.)

[0151] In formula (4-1), there is no particular restriction on the arrangement order of (OCF2CF2) and (OCF2) as repeating units. In formula (4-1), the number h of (OCF2CF2) and the number i of (OCF2) may be the same or different. The PFPE chain shown in formula (4-1) may be a polymer of (OCF2CF2). In addition, the PFPE chain shown in formula (4-1) may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of (OCF2CF2) and (OCF2).

[0152] In formula (4-1) to formula (4-3), since h, which represents the average degree of polymerization, is 1 to 20, i is 0 to 20, j is 1 to 15, and k is 1 to 10, it is a fluorine-containing ether compound that can obtain a lubricating layer with good lubricity. In addition, in formula (4-1) to formula (4-3), since h and i, which represent the average degree of polymerization, are 20 or less, j is 15 or less, and k is 10 or less, the viscosity of the fluorine-containing ether compound does not become too high, and the lubricant containing the fluorine-containing ether compound is easy to apply and is preferred. In order to obtain a fluorine-containing ether compound that is easy to wet and spread on the protective layer and easy to obtain a lubricating layer with a uniform film thickness, h, i, j, and k, which represent the average degree of polymerization, are preferably 1 to 10, more preferably 1.5 to 8, and further preferably 2 to 7.

[0153] In formula (4-4), there is no particular restriction on the arrangement order of (CF2CF2CF2O) and (CF2CF2O) as repeating units. In formula (4-4), the number w8 of (CF2CF2CF2O) representing the average degree of polymerization and the number w9 of (CF2CF2O) may be the same or different. Formula (4-4) may include any of a random copolymer, a block copolymer, and an alternating copolymer composed of monomer units (CF2CF2CF2O) and (CF2CF2O).

[0154] In formula (4-4), w8 and w9 representing the average degree of polymerization are each independently 1 to 20, preferably 1 to 15, and more preferably 1 to 10.

[0155] w7 and w10 in formula (4-4) are average values ​​representing the number of CF2, and each independently represents 1 to 2. w7 and w10 are determined by the structure of the repeating unit arranged at the end of the chain structure in the PFPE chain represented by formula (4-4).

[0156] (R 1 and R 6 terminal groups shown)

[0157] In the fluorine-containing ether compound represented by formula (1), R 1 and R 6The terminal groups shown are each independently an organic group having 1 to 50 carbon atoms. 1 and R 6 The terminal groups shown are each independently preferably an organic group having 1 to 20 carbon atoms, and more preferably an organic group having 2 to 10 carbon atoms.

[0158] R 1 The terminal groups shown are preferably 2 The end of the bond is a carbon atom. 6 The terminal groups shown are preferably 5 The end of the bond is a carbon atom. 1 (or R 6 ) has a polar group, R 2 (or R 5 ) has a primary hydroxyl group, and R 1 (or R 6 ) becomes more appropriate. As a result, 1 (or R 6 ) adjacent R 2 (or R 5 ) has a primary hydroxyl group that is more difficult to 1 (or R 6 ) and hinder the binding with the active points on the protective layer.

[0159] In order to further improve the chemical resistance, R 1 and R 6 The terminal group represented by formula (1) preferably does not contain a secondary hydroxyl group (ie, the fluorine-containing ether compound represented by formula (1) does not contain a secondary hydroxyl group).

[0160] R 1 and R 6 Preferably, each independently is an organic group having a polar group, an organic group having a carbon-carbon unsaturated bond, or an organic group having both a polar group and a carbon-carbon unsaturated bond.

[0161] When the terminal group has a polar group, the polar group is preferably selected from hydroxyl (-OH), amino (-NR 7 R 8 ; R 7 and R 8 Each is independently a hydrogen atom or an organic group. ), carboxyl (-COOH), formyl (-(C=O)H), carbonyl (-CO-), sulfonyl (-SO3H), cyano (-CN), and a group having an amide bond (-NR 9 COR 10 or-CONR 11 R 12 ; R 9 , R 10, R 11 and R 12 Each independently represents a hydrogen atom or an organic group. ) In addition, as shown in the above formula, the "group having an amide bond" includes both a group that is bonded to an organic group on a carbon atom constituting an amide bond (e.g., a carbamoyl group (-C(=O)NH2)) and a group that is bonded to an organic group on a nitrogen atom constituting an amide bond (e.g., an acetylamino group (-NHC(=O)CH3)). In the group having an amide bond, the above R 9 With R 10 can be combined with each other to form a ring, the above R 11 With R 12 The above R in the group having an amide bond may be bonded to each other to form a ring. 9 , R 10 , R 11 and R 12 Preferably, they are each independently selected from a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group.

[0162] Among these polar groups, at least one polar group selected from a hydroxyl group, a cyano group, and a group having an amide bond is more preferable because it is a fluorine-containing ether compound that can form a lubricating layer having better chemical resistance and a greater pickup suppression effect.

[0163] When the terminal group has a polar group, the number of the polar groups is preferably 1 to 3, and more preferably 1 to 2. When the number of the polar groups is 2 or more, some or all of the polar groups may be the same or different.

[0164] The organic group having a polar group is preferably represented by -CH2-Y, -CH2CH2-Y, -CH2-O-CH2CH2-Y, -CH2-O-CH2CH2CH2-Y, -CH2-O-CH2CH(OH)CH2-O-CH2CH2-Y, or -CH2-O-CH2CH(OH)CH2-O-CH2CH2CH2-Y (Y in the above formulas is a polar group).

[0165] When the terminal group has a carbon-carbon unsaturated bond, the terminal group is preferably at least one organic group having a carbon-carbon unsaturated bond selected from an aromatic hydrocarbon group, an unsaturated heterocyclic group, an alkenyl group, and an alkynyl group which may have a substituent.

[0166] Specifically, examples of the aromatic hydrocarbon group which may have a substituent include a phenyl group, a methoxyphenyl group, a fluorophenyl group, a naphthyl group, and a methoxynaphthyl group.

[0167] Examples of the unsaturated heterocyclic group include pyrrolyl, pyrazolyl, imidazolyl, furanyl, furfuryl, Azolyl, iso oxazolyl, thienyl, thiazolyl, isothiazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, indolinyl, benzofuranyl, benzothiophenyl, benzimidazolyl, benzo Azolyl, benzothiazolyl, benzopyrazolyl, benzisophthalic acid oxazolyl, benzisothiazolyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, phthalazinyl, cinnolinyl and the like.

[0168] Examples of the alkenyl group include an allyl group and a butenyl group.

[0169] Examples of the alkynyl group include propargyl and the like.

[0170] When the terminal group has a carbon-carbon unsaturated bond, the terminal group is preferably an organic group having a carbon-carbon unsaturated bond selected from any one of phenyl, methoxyphenyl, naphthyl, thienyl, and allyl groups. The reason is that it can form a lubricating layer with better chemical resistance and better pickup suppression effect.

[0171] The organic group having a carbon-carbon unsaturated bond is preferably an organic group represented by -CH2-OZ or -CH2CH2-OZ (wherein Z is any one selected from an aromatic hydrocarbon group which may have a substituent, an unsaturated heterocyclic group, an alkenyl group, and an alkynyl group).

[0172] The organic group having both a polar group and a carbon-carbon unsaturated bond is preferably an organic group represented by -CH2-O-CH2CH(OH)CH2-OZ, or -CH2CH2-O-CH2CH(OH)CH2-OZ (wherein Z is any one selected from an aromatic hydrocarbon group which may have a substituent, an unsaturated heterocyclic group, an alkenyl group, and an alkynyl group).

[0173] In the fluorine-containing ether compound represented by formula (1), R 1 and R 6 Preferably, each independently is an end group represented by any one of the following formulas (5-1) to (5-8). The following formulas (5-1) to (5-3) are all organic groups having only one primary hydroxyl group as a polar group. The following formula (5-4) is an organic group having one primary hydroxyl group and one secondary hydroxyl group as polar groups. The following formula (5-5) is an organic group having one secondary hydroxyl group as a polar group and further having one allyl group as a group having a carbon-carbon unsaturated bond. The following formula (5-6) is an organic group having one secondary hydroxyl group as a polar group and further having one phenyl group as a group having a carbon-carbon unsaturated bond. The following formula (5-7) is an organic group having one cyano group as a polar group. The following formula (5-8) is an organic group having one group (-NHCOCH3) having an amide bond as a polar group.

[0174]

[0175] (The dotted lines in equations (5-1) to (5-8) represent the 2 or R 5 The bonds that bind the carbon atoms it has.)

[0176] In R 1 and / or R 6 When the terminal group has a polar group, the lubricating layer containing the fluorinated ether compound and the protective layer have better adhesion and can be made thinner, which is preferred. The reason is described below.

[0177] In R 2 and R 5 In the side chain portion, the carbon atom to which the primary hydroxyl group disposed at the front end is bonded is bonded to the oxygen atom bonded to the carbon atom of the main chain portion via a linker containing a methylene group (-CH2-). 1 (or R 6 ) contains a polar group, R 1 (or R 6 ) has a polar group, and R 2 (or R 5 ) also becomes appropriate. As a result, R 2 (or R 5 ) has a primary hydroxyl group, and R 1 (or R 6 ) is not easily hindered from combining with the active points on the protective layer by other polar groups. 2 (or R 5 ) has a primary hydroxyl group and R 1 (or R 6 ) has a polar group that is not easy to agglomerate.

[0178] Therefore, R 2 (or R 5 ) has a primary hydroxyl group, and R 1 (or R 6 ) can be adsorbed independently on the active points on the protective layer. 1 and / or R 6 The lubricating layer of the fluorinated ether compound having a polar group at the terminal group has a more excellent adhesion to the protective layer, exhibits good chemical resistance even when the thickness is thin, and has a high pickup suppression effect.

[0179] In order to improve the adhesion with the protective layer and realize the thinning of the lubricating layer, R 1 With R 6The total number of polar groups contained is preferably 1 or more, more preferably 2 or more. In the fluorinated ether compound represented by formula (1), in order to prevent the polar groups from becoming excessive and thus generating polar groups that do not participate in the bonding with the protective layer, R 1 With R 6 The total number of polar groups contained is preferably 4 or less, more preferably 3 or less, and most preferably 2 or less.

[0180] In addition, in R 1 and / or R 6 When the terminal group has a carbon-carbon unsaturated bond, the lubricating layer containing the fluorine-containing ether compound and the protective layer have better adhesion and can be made thinner, which is preferred. The reason is described below.

[0181] Among the functional groups (active sites) present in large quantities in the protective layer, there are sites where local charge is applied and sites where the charge distribution is expanded. 2 , R 4 and R 5 The hydroxyl groups contained in R 1 and / or R 6 The carbon-carbon unsaturated bonds contained in the terminal groups shown are adsorbed to different positions on the protective layer. Specifically, R in formula (1) 2 , R 4 and R 5 The hydroxyl groups contained in the protective layer interact with the locally charged sites on the protective layer through hydrogen bonds via hydrogen atoms, thereby exhibiting adsorption capacity. 1 and / or R 6 Since the carbon-carbon unsaturated bond contained in the terminal group has a non-localized charge, it exhibits adsorption capability by interacting with a site where the charge distribution on the protective layer is expanded.

[0182] Therefore, R in formula (1) 2 , R 4 and R 5 The hydroxyl groups contained in R 1 and / or R 6 The carbon-carbon unsaturated bonds contained in the terminal groups shown can interact independently with the functional groups (active sites) on the protective layer. 1 and / or R 6 The fluorinated ether compound having a carbon-carbon unsaturated bond at the terminal group has a more excellent adhesion between the lubricating layer and the protective layer, exhibits good chemical resistance even with a thin thickness, and has a high pickup suppression effect.

[0183] In the fluorine-containing ether compound represented by formula (1), R 1 and R 6The type of the terminal group shown above can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound, etc.

[0184] In the fluorine-containing ether compound represented by formula (1), R 1 With R 6 They can be the same or different. 1 With R 6 If the coating state of the protective layer with the fluorinated ether compound is the same, the coating state of the protective layer with the fluorinated ether compound becomes more uniform, and a lubricating layer with better adhesion can be formed.

[0185] Among the fluorine-containing ether compounds represented by formula (1), it is preferred that R in formula (1) 1 -R 2 -With R 6 -R 5 This is because it is a fluorine-containing ether compound that can be easily and efficiently produced.

[0186] Among the fluorine-containing ether compounds represented by formula (1), the (x+1)th R in formula (1) is more preferably 3 All the same, x R 4 All the same, R 1 -R 2 -With R 6 -R 5 This is because it is a fluorine-containing ether compound that can be produced more easily and efficiently.

[0187] Specifically, the fluorine-containing ether compound represented by the formula (1) is preferably any one of the compounds represented by the following formulas (A) to (X) and (XX).

[0188] When the compound represented by formula (1) is any of the compounds represented by formula (A) to formula (X) or formula (XX), the raw material is easily available and a lubricating layer having excellent chemical resistance and a good pickup suppression effect can be formed.

[0189] In the compounds represented by the following formulas (A) to (X) and (XX), Rf1, Rf2 and Rf3 representing the PFPE chain are respectively the following structures. That is, in the compounds represented by the following formulas (A) to (K), (N) to (R), (T) to (W) and (XX), Rf1 is the PFPE chain represented by the above formula (4-1). In the compounds represented by the following formulas (L), (S) and (X), Rf2 is the PFPE chain represented by the above formula (4-2). In the compound represented by the following formula (M), Rf3 is the PFPE chain represented by the above formula (4-3). In addition, h and i in Rf1 representing the PFPE chain in formulas (A) to (X) and (XX), j in Rf2 and k in Rf3 are not necessarily integers because they are values ​​representing the average degree of polymerization.

[0190]

[0191] The compounds represented by the following formulas (A) to (X) and (XX) are all R 2 is a linking group represented by the above formula (2-1) or formula (2-2), and R 5 It is a linking group represented by the above formula (2-3) or formula (2-4).

[0192] The compounds represented by the following formulae (A) to (M) are all those in which x in formula (1) is 0 and does not contain R in the structure. 4 The compounds represented by the following formulas (N) to (X) and (XX) are all compounds wherein x in formula (1) is 1 or 2 and contains 1 or 2 R 4 The compounds represented by the following formulas (N) to (X) and (XX) are all R 4 It is a linking group represented by the above formula (3-1) or (3-2).

[0193] In the compounds represented by the following formulae (A) to (H), x in the formula (1) is 0. 1 and R 6 is any terminal group represented by the above formula (5-1) to formula (5-8). 2 All are linking groups represented by the above formula (2-1), and n1 is 2. 5 All are linking groups represented by the above formula (2-3), and n2 is 2. 3 All are PFPE chains represented by the above formula (4-1).

[0194] In the compounds represented by the following formula (I) and formula (J), x in formula (1) is 0. In the compounds represented by the following formula (I) and formula (J), R 1 and R 6 are terminal groups represented by the above formula (5-1), R 3 It is the PFPE chain represented by the above formula (4-1).

[0195] The compound represented by the following formula (I) has R 2 is a linking group represented by the above formula (2-1), and n1 is 3. 5 It is a linking group represented by the above formula (2-3), and n2 is 3.

[0196] The compound represented by the following formula (J) has R 2 is a linking group represented by the above formula (2-1), and n1 is 4. 5 It is a linking group represented by the above formula (2-3), and n2 is 4.

[0197] In the compound represented by the following formula (K), x in the formula (1) is 0.1 and R 6 is the terminal group represented by the above formula (5-1). 2 is a linking group represented by the above formula (2-2). 5 is a linking group represented by the above formula (2-4). 3 It is the PFPE chain represented by the above formula (4-1).

[0198] In the compounds represented by the following formula (L) and formula (M), x in formula (1) is 0. In the compounds represented by the following formula (L) and formula (M), R 1 and R 6 is the terminal group represented by the above formula (5-1). 2 All are linking groups represented by the above formula (2-1), and n1 is 2. 5 All are linking groups represented by the above formula (2-3), and n2 is 2.

[0199] R of the compound represented by the following formula (L) 3 is the PFPE chain represented by the above formula (4-2). R of the compound represented by the following formula (M) 3 It is the PFPE chain represented by the above formula (4-3).

[0200] In the compounds represented by the following formulae (N) to (P), x in the formula (1) is 1. 2 is a linking group represented by the above formula (2-1), and n1 is 2. 5 is a linking group represented by the above formula (2-3), and n2 is 2. 4 is a linking group represented by the above formula (3-1), n3 is 2, y1 is 1, and y2 is 1. The two R 3 All are PFPE chains represented by the above formula (4-1).

[0201] R of the compound represented by the following formula (N) 1 and R 6 is the terminal group represented by the above formula (5-1). 1 and R 6 is the terminal group represented by the above formula (5-3). 1 and R 6 It is the terminal group represented by the above formula (5-7).

[0202] In the compound represented by the following formula (Q), x in the formula (1) is 1. 1 and R 6 is the terminal group represented by the above formula (5-1). 2 is a linking group represented by the above formula (2-1), and n1 is 3.5 is a linking group represented by the above formula (2-3), and n2 is 3. 4 is a linking group represented by the above formula (3-1), n3 is 3, y1 is 1, and y2 is 1. 2 R 3 All are PFPE chains represented by the above formula (4-1).

[0203] In the compound represented by the following formula (R), x in the formula (1) is 1. 1 and R 6 is the terminal group represented by the above formula (5-1). 2 is a linking group represented by the above formula (2-2). 5 is a linking group represented by the above formula (2-4). 4 is a linking group represented by the above formula (3-2), y3 is 1, y4 is 1. 2 R 3 All are PFPE chains represented by the above formula (4-1).

[0204] In the compound represented by the following formula (S), x in the formula (1) is 1. 1 and R 6 is the terminal group represented by the above formula (5-1). 2 is a linking group represented by the above formula (2-1), and n1 is 2. 5 is a linking group represented by the above formula (2-3), and n2 is 2. 4 is a linking group represented by the above formula (3-1), n3 is 2, y1 is 1, and y2 is 1. 2 R 3 All are PFPE chains represented by the above formula (4-2).

[0205] The compounds represented by the following formulae (T) to (V) are all those wherein x in the formula (1) is 2. 2 is a linking group represented by the above formula (2-1), and n1 is 2. 5 is a linking group represented by the above formula (2-3), and n2 is 2. 2 R 4 are all linking groups represented by the above formula (3-1), n3 is 2, y1 is 1, and y2 is 1. 3 All are PFPE chains represented by the above formula (4-1).

[0206] The R of the compound represented by the following formula (T) 1 and R 6 is the terminal group represented by the above formula (5-1). R of the compound represented by the following formula (U) 1 and R 6 The compound represented by the following formula (V) has an R 1 and R 6 It is the terminal group represented by the above formula (5-7).

[0207] In the compound represented by the following formula (W), x in the formula (1) is 2. 1 and R 6 is the terminal group represented by the above formula (5-1). 2 is a linking group represented by the above formula (2-2). 5 is a linking group represented by the above formula (2-4). 4 are all linking groups represented by the above formula (3-2), y3 is 1, y4 is 1. The three R 3 All are PFPE chains represented by the above formula (4-1).

[0208] In the compound represented by the following formula (X), x in the formula (1) is 2. 1 and R 6 is the terminal group represented by the above formula (5-1). 2 is a linking group represented by the above formula (2-1), and n1 is 2. 5 is a linking group represented by the above formula (2-3), and n2 is 2. 2 R 4 are all linking groups represented by the above formula (3-1), n3 is 2, y1 is 1, and y2 is 1. 3 All are PFPE chains represented by the above formula (4-2).

[0209] In the compound represented by the following formula (XX), x in the formula (1) is 1. 1 and R 6 is the terminal group represented by the above formula (5-2). 2 is a linking group represented by the above formula (2-1), and n1 is 2. 5 is a linking group represented by the above formula (2-3), and n2 is 2. 4 is a linking group represented by the above formula (3-1), n3 is 2, y1 is 1, and y2 is 1. 2 R 3 All are PFPE chains represented by the above formula (4-1).

[0210]

[0211] (In Rf1 in formula (A), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (B), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (C), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (D), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (E), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (F), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.)

[0212]

[0213] (In Rf1 in formula (G), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (H), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (I), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (J), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf1 in formula (K), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20.) (In Rf2 in formula (L), j represents average polymerization degree, and represents 1 to 15.)

[0214] (In Rf3 in formula (M), k represents an average degree of polymerization and is 1 to 10.)

[0215]

[0216] (In the two Rf1 in formula (N), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0217] (In the two Rf1 in formula (O), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0218] (In the two Rf1 in formula (P), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0219] (In the two Rf1 in formula (Q), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0220] (In the two Rf1 in formula (R), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; in the two Rf1, the average degree of polymerization may be the same or different.)

[0221] (In the two Rf2 in formula (S), j represents the average degree of polymerization and is 1 to 15; in the two Rf2, the average degree of polymerization may be the same or different.)

[0222]

[0223] (In the three Rf1 in formula (T), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; the average polymerization degrees of the three Rf1 may be different from each other, and the average polymerization degrees of two or three Rf1 may be the same.)

[0224] (In the three Rf1 in formula (U), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; the average polymerization degrees of the three Rf1 may be different from each other, and the average polymerization degrees of two or three Rf1 may be the same.)

[0225] (In the three Rf1 in formula (V), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; the average polymerization degrees of the three Rf1 may be different from each other, and the average polymerization degrees of two or three Rf1 may be the same.)

[0226]

[0227] (In the three Rf1 in formula (W), h and i represent average polymerization degrees, h represents 1 to 20, and i represents 0 to 20; the average polymerization degrees of the three Rf1 may be different from each other, and the average polymerization degrees of two or three Rf1 may be the same.)

[0228] (In the three Rf2 in formula (X), j represents the average degree of polymerization and represents 1 to 15; the average degree of polymerization in the three Rf2 may be different from each other, and the average degree of polymerization in two or three Rf2 may be the same.)

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

[0230] The fluorinated ether compound of the present embodiment preferably has a number average molecular weight (Mn) in the range of 500 to 10,000, and particularly preferably in the range of 1,000 to 5,000. If the number average molecular weight is 500 or more, the lubricating layer formed by the lubricant containing the fluorinated ether compound of the present embodiment has excellent heat resistance. The number average molecular weight of the fluorinated ether compound is more preferably 1,000 or more. In addition, if the number average molecular weight is 10,000 or less, the viscosity of the fluorinated ether compound becomes appropriate, and a lubricating layer with a thin film thickness can be easily formed by applying the lubricant containing the fluorinated ether compound. In order to achieve a viscosity that is easy to handle when used as a lubricant, the number average molecular weight of the fluorinated ether compound is preferably 5,000 or less.

[0231] The number average molecular weight (Mn) of the fluorinated ether compound was determined by using AVANCE III 400 manufactured by Bruker Biospin Co., Ltd. 1 H-NMR and 19 Specifically, the value measured by 19 The number of repeating units of the PFPE chain was calculated from the integrated value measured by F-NMR to determine the number average molecular weight. In the measurement of NMR (nuclear magnetic resonance), the sample was diluted in a hexafluorobenzene / d-acetone (4 / 1 v / v) solvent for measurement. 19 The standard of F-NMR chemical shift is the peak of hexafluorobenzene at -164.7 ppm. 1 The standard of H-NMR chemical shift was set at 2.2 ppm based on the peak of acetone.

[0232] The fluorine-containing ether compound of the present embodiment is preferably subjected to molecular weight fractionation by an appropriate method so that the molecular weight distribution (ratio of weight average molecular weight (Mw) / number average molecular weight (Mn)) is 1.3 or less.

[0233] In the present embodiment, the method for molecular weight fractionation is not particularly limited, and for example, 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 used.

[0234] "Manufacturing method"

[0235] The method for producing the fluorinated ether compound of the present embodiment is not particularly limited, and can be produced using a conventionally known method. The fluorinated ether compound of the present embodiment can be produced, for example, using a method having a first reaction step for forming a main chain portion of a chain structure of the fluorinated ether compound and a second reaction step for forming a side chain portion branched from the main chain portion, as shown below.

[0236] The first reaction step is preferably to synthesize a fluorine-containing ether compound having a chain structure R in the formula (1).2 , R 5 (When x is 1 or 2, R 2 , R 4 , R 5 ) is a step of producing a first intermediate compound of a compound having a structure in which secondary hydroxyl groups are respectively arranged on the main chain portion.

[0237] In the second reaction step, it is preferred to react R 2 , R 5 (When x is 1 or 2, R 2 , R 4 , R 5 ) is a step of chemically modifying the secondary hydroxyl groups in the main chain portion to form a side chain portion having a primary hydroxyl group.

[0238] [First Manufacturing Method]

[0239] When producing a fluorine-containing ether compound in which x in the formula (1) is 0, for example, the following first production method can be used.

[0240] First, prepare the R 3 A fluorine-based compound having a hydroxymethyl group (-CH2OH) is disposed at both ends of the corresponding perfluoropolyether chain.

[0241] (First Reaction Step)

[0242] <R 1 With R 6 Same situation>

[0243] In the manufacturing formula (1), x is 0, and R 1 With R 6 In the case of the same fluorine-containing ether compound, in the first reaction step, the hydroxyl groups of the hydroxymethyl groups disposed at both ends of the fluorine-containing compound are reacted with the hydroxyl groups corresponding to R in formula (1). 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 6 The corresponding groups and R 5 The epoxy compound is reacted with a group obtained by bonding the group corresponding to the main chain part of the epoxy compound.

[0244] Through the above reaction, the 3 The two ends of the corresponding perfluoropolyether chain have 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 6 The corresponding groups and R 5In the first intermediate compound 1a, in the case of R 2 The main chain part corresponds to the group and R 5 Each of the groups corresponding to the main chain portion is provided with one secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group with the epoxy group of the epoxy compound in the first reaction step.

[0245] <R 1 With R 6 Different situations>

[0246] In the manufacturing formula (1), x is 0, and R 1 With R 6 In the case of different compounds, in the first reaction step, the hydroxyl group of the hydroxymethyl group disposed at one end of the fluorine-based compound is reacted with the hydroxyl group corresponding to R in formula (1). 1 The corresponding groups and R 2 Then, the hydroxyl group of the hydroxymethyl group disposed at the other end of the fluorine-based compound is reacted with the hydroxyl group corresponding to R in formula (1). 6 The corresponding groups and R 5 The epoxy compound of the group obtained by combining the group corresponding to the main chain part is reacted.

[0247] In this case, the first reaction step may be a step of reacting a hydroxyl group of a hydroxymethyl group disposed at one end of the fluorine-based compound with a hydroxyl group corresponding to R in formula (1). 6 The corresponding groups and R 5 After reacting with an epoxy compound of a group obtained by bonding a group corresponding to the main chain portion of the fluorine-based compound, the hydroxyl group of the hydroxymethyl group disposed at the other end of the fluorine-based compound is reacted with the hydroxyl group corresponding to R in the formula (1). 1 The corresponding groups and R 2 The epoxy compound of the group obtained by combining the group corresponding to the main chain part is reacted.

[0248] Through the above reaction, the 3 One end of the corresponding perfluoropolyether chain has 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 6 The corresponding groups and R 5 The first intermediate compound 1b is obtained by combining the groups corresponding to the main chain parts of 2 The main chain part corresponds to the group and R 5Each of the groups corresponding to the main chain portion is provided with one secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group with the epoxy group of the epoxy compound in the first reaction step.

[0249] As the compound corresponding to R in the formula (1) used in the first reaction step 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of R 6 The corresponding groups and R 5 As the epoxy compound containing a group obtained by bonding a group corresponding to the main chain portion of ), for example, compounds represented by the following formulas (7-1) to (7-8) can be used.

[0250]

[0251] (In formula (7-1) to formula (7-4), THP represents tetrahydropyranyl.)

[0252] (In formula (7-4) to formula (7-6), MOM represents a methoxymethyl group.)

[0253] The epoxy compound used in the first reaction step can be prepared by, for example, making the epoxy compound have an R 1 (or R 6 ) corresponding to the structure of the alcohol, and epichlorohydrin or epibromohydrin reaction method of synthesis. The epoxy compound used in the first reaction step can be synthesized by the method of oxidizing a compound having a carbon-carbon double bond, can also be purchased and used.

[0254] (Second Reaction Step)

[0255] <R 2 The side chain part of R 5 When the side chain parts are the same>

[0256] In the manufacturing formula (1), x is 0, and R 2 The side chain part of R 5 In the case of a fluorinated ether compound having the same side chain moiety as R in formula (1), in the second reaction step, 2 The side chain part (=R 5 A halide having a protected hydroxyl group corresponding to the side chain portion of the first intermediate compound 1a) reacts with a secondary hydroxyl group of the first intermediate compound 1a or the first intermediate compound 1b produced by the first reaction step to produce a second intermediate compound 2a.

[0257] <R 2 The side chain part of R 5 When the side chain part is different >

[0258] In the manufacturing formula (1), x is 0, and R 2 The side chain part of R 5 In the case of a fluorine-containing ether compound having a side chain portion different from that of R in the formula (1), in the second reaction step, 2 The side chain portion of the corresponding halide having a protected hydroxyl group, and R 5 The halide having a protected hydroxyl group corresponding to the side chain portion of R is sequentially reacted with the secondary hydroxyl group of the first intermediate compound 1a or the first intermediate compound 1b produced by the first reaction step using a known method to produce the second intermediate compound 2b. After the reaction, it is purified by a known method such as column chromatography as needed to obtain a second intermediate compound 2b having R 2 The side chain part and R 5 The order of reaction with the first intermediate compound 1a or the first intermediate compound 1b is the same as R 2 The side chain portion of the corresponding halide having a protected hydroxyl group, and R 5 The halides having protected hydroxyl groups corresponding to the side chain portions may be placed first.

[0259] As the R in the formula (1) used in the second reaction step 2 The side chain part (or R 5 As the halide having a protected hydroxyl group corresponding to the side chain portion of the side chain, for example, the compounds represented by the following formula (8-1) to (8-4) can be used.

[0260]

[0261] (In formula (8-1) to formula (8-4), THP represents tetrahydropyranyl.)

[0262] Next, a deprotection reaction is performed to remove the protecting group derived from the halide having the protected hydroxyl group possessed by the second intermediate compound 2a or the second intermediate compound 2b by a known method corresponding to the type of the protecting group. 2 The side chain part and R 5 One primary hydroxyl group is respectively arranged at the front end of the side chain portion.

[0263] By carrying out the above steps, a fluorine-containing ether compound wherein x in the formula (1) is 0 is obtained.

[0264] [Second Manufacturing Method]

[0265] When producing a fluorine-containing ether compound wherein x in the formula (1) is 1, for example, the second production method described below can be used.

[0266] (First Reaction Step)

[0267] <2 R 3 Same, R 1 With R 6 Same situation>

[0268] In the manufacturing formula (1), x is 1, 2 R 3 The same, and R 1 With R 6 In the case of the same compound, first, similarly to the first production method, a 3 The corresponding perfluoropolyether chain has fluorine compounds having hydroxymethyl groups (-CH2OH) at both ends.

[0269] Next, the hydroxyl group of one of the hydroxymethyl groups disposed at the two ends of the fluorine-based compound is reacted with the hydroxyl group corresponding to R in formula (1). 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 6 The corresponding groups and R 5 After the reaction, it is purified by a known method such as column chromatography as needed to obtain a compound obtained by reacting the hydroxymethyl group configured at one end among the hydroxymethyl groups configured at both ends of the fluorine-based compound and the epoxy compound.

[0270] Through the above reaction, the 3 One end of the corresponding perfluoropolyether chain has 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 6 The corresponding groups and R 5 In the precursor compound 11a, in the case of R 2 The group corresponding to the main chain part (= with R 5 The group corresponding to the main chain portion of is provided with a secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group with the epoxy group of the epoxy compound.

[0271] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the precursor compound 11a is reacted with R 4 The halogen compound having an epoxy group corresponding to the main chain portion is reacted.

[0272] Through this reaction, the R 4The two ends of the structure corresponding to the main chain part have R 3 The corresponding perfluoropolyether chain further has R 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 6 The corresponding groups and R 5 In the first intermediate compound 1c, the first intermediate compound 1c is a group obtained by bonding a group corresponding to the main chain portion of R 4 The group corresponding to the main chain portion is configured with one secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group and the epoxy group of the epoxy compound.

[0273] <2 R 3 Different and / or R 1 With R 6 Different situations>

[0274] In the manufacturing formula (1), x is 1 and 2 R 3 Different compounds, and / or R 1 With R 6 In the case of different compounds, first, prepare 1 Side R 3 A fluorine-based compound having hydroxymethyl groups (-CH2OH) disposed at both ends of the corresponding perfluoropolyether chain is used. Precursor compound 11b is produced in the same manner as in the production of precursor compound 11a except that the fluorine-based compound is used.

[0275] Precursor compound 11b reacts with R 1 Side R 3 One end of the corresponding perfluoropolyether chain has 1 The corresponding groups and R 2 In the precursor compound 11b, in the case of R 2 The group corresponding to the main chain portion is configured with one secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group and the epoxy group of the epoxy compound.

[0276] Next, prepare the R 6 Side R 3 The corresponding perfluoropolyether chain has a fluorine compound having hydroxymethyl groups (-CH2OH) at both ends. Furthermore, the hydroxyl group of one of the hydroxymethyl groups at the two ends of the fluorine compound is connected to the corresponding R in formula (1). 6 The corresponding groups and R 5After the reaction, it is purified by a known method such as column chromatography as needed to obtain a compound obtained by reacting the hydroxymethyl group arranged at one end of the hydroxymethyl groups arranged at both ends of the fluorine-based compound with the epoxy compound.

[0277] Through the above reaction, the 6 Side R 3 One end of the corresponding perfluoropolyether chain has 6 The corresponding groups and R 5 The precursor compound 11c is obtained by combining the corresponding groups of the main chain of 5 The group corresponding to the main chain portion is configured with one secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group and the epoxy group of the epoxy compound.

[0278] Next, the hydroxyl group of the hydroxymethyl group disposed at one end of the precursor compound 11b is reacted with R 4 The obtained reaction product is then reacted with a hydroxyl group of a hydroxymethyl group disposed at one end of the precursor compound 11c. 4 After reacting a halogen compound having an epoxy group corresponding to the main chain portion of the precursor compound 11c, the obtained reaction product is reacted with the precursor compound 11b.

[0279] Through these reactions, we can obtain 4 The main chain portion corresponds to the structure R 1 The end of the side has an R 1 Side R 3 The corresponding perfluoropolyether chain further has at the end thereof a 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of 4 The main chain portion corresponds to the structure R 6 The end of the side has an R 6 Side R 3 The corresponding perfluoropolyether chain further has at the end thereof a 6 The corresponding groups and R 5 In the first intermediate compound 1d, the first intermediate compound 1d is obtained by combining the group corresponding to the main chain part of 4 The group corresponding to the main chain portion is configured with a secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group with the epoxy group.

[0280] As the first reaction step of the second production method, 4 The halogen compound having an epoxy group corresponding to the main chain portion of can be, for example, epibromohydrin, epichlorohydrin, 2-bromoethyl oxirane, 3-bromopropyl oxirane, 2-chloroethyl oxirane, 3-chloropropyl oxirane, etc. In formula (1), R 4 According to formula (3-1), when y1 and y2 in formula (3-1) are both 1, or, in R 4 In the case where both y3 and y4 in the formula (3-2) are 1, for example, epibromohydrin and epichlorohydrin can be used.

[0281] As the compound used in the first reaction step of the second production method, the compound corresponding to R in the formula (1) 1 The corresponding groups and R 2 The group obtained by combining the group corresponding to the main chain part of R 6 The corresponding groups and R 5 The epoxy compound obtained by bonding a group corresponding to the main chain portion of ) can be the same epoxy compound as in the first production method.

[0282] (Second Reaction Step)

[0283] <R 2 The side chain part of R 4 The side chain part of R 5 When the side chain parts are the same>

[0284] In the manufacturing formula (1), x is 1, and R 2 The side chain part of R 4 The side chain part of R 5 In the case of a fluorinated ether compound having the same side chain moiety as R in formula (1), in the second reaction step, 2 The side chain part (=R 4 The side chain part and R 5 A halide having a protected hydroxyl group corresponding to the side chain portion of the first intermediate compound 1c or the secondary hydroxyl group of the first intermediate compound 1d produced by the first reaction step reacts with the halide having a protected hydroxyl group corresponding to the side chain portion of the first intermediate compound 1c to produce the second intermediate compound 2c.

[0285] <R 2 The side chain part of R 4 The side chain part of R 5 When part or all of the side chain parts of are different>

[0286] In the manufacturing formula (1), x is 1, and R 2 The side chain part of R 4The side chain part of R 5 In the case of a fluorine-containing ether compound having a part or all of a different side chain portion, in the second reaction step, R 2 , R 4 and R 5 The halide having a protected hydroxyl group corresponding to each side chain part of the first intermediate compound 1c or the secondary hydroxyl group of the first intermediate compound 1d produced by the first reaction step is reacted in sequence using a known method to produce the second intermediate compound 2d. After the reaction, it is purified by a known method such as column chromatography as needed to obtain a second intermediate compound 2d having R 2 The side chain part, R 4 The side chain part and R 5 The side chain of the second intermediate compound 2d is 2 , R 4 and R 5 The order in which the halide having a protected hydroxyl group corresponding to each side chain portion of is reacted with the first intermediate compound 1c or the first intermediate compound 1d is not particularly limited.

[0287] As the compound used in the second reaction step of the second production method, 2 , R 4 and R 5 The halides having protected hydroxyl groups corresponding to the side chain portions of can be, for example, the halides that can be used in the first production method and that are compatible with R in formula (1) 2 and R 5 The halide having a protected hydroxyl group corresponding to each side chain portion is the same halide.

[0288] Next, a deprotection reaction is performed to remove the protecting group derived from the halide having the protected hydroxyl group possessed by the second intermediate compound 2c or the second intermediate compound 2d by a known method corresponding to the type of the protecting group. 2 The side chain part, R 4 The side chain part and R 5 One primary hydroxyl group is respectively arranged at the front end of the side chain portion.

[0289] By carrying out the above steps, a fluorine-containing ether compound wherein x in the formula (1) is 1 is obtained.

[0290] [Third Manufacturing Method]

[0291] When producing a fluorine-containing ether compound in which x in the formula (1) is 2, for example, the third production method described below can be used.

[0292] (First Reaction Step)

[0293] <3 R 3 Same, 2 R 4 Same, R 1 With R 6 Same situation>

[0294] In the manufacturing formula (1), x is 2 and 3 R 3 Same, 2 R 4 Same, R 1 With R 6 In the case of the same compound, first, the precursor compound 11a is produced in the same manner as in the second production method.

[0295] Next, prepare the R 3 The corresponding perfluoropolyether chain has hydroxymethyl (-CH2OH) groups at both ends of the fluorine-based compound. Next, the hydroxyl groups of the hydroxymethyl groups at both ends of the fluorine-based compound are combined with R 4 The halogen compound having an epoxy group corresponding to the main chain portion of is reacted. Thus, the R 3 The corresponding perfluoropolyether chain has two ends with R 4 The main chain portion corresponds to the epoxy group of the precursor compound 11d.

[0296] Then, the hydroxyl group of the hydroxymethyl group disposed at one end of the precursor compound 11a and the R 4 The first intermediate compound 1e is prepared by reacting the epoxy groups corresponding to the main chain of the first intermediate compound 1e. 4 The groups corresponding to the main chain portion are each provided with a secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group with the epoxy group.

[0297] <2 R 4 Same, 3 Rs 3 Some or all of them are different, and / or R 1 With R 6 Different situations>

[0298] In the manufacturing formula (1), x is 2 and 2 R 4 Same, 3 Rs 3 Some or all of them are different, and / or R 1 With R 6 In the case of different compounds, the following methods can be used.

[0299] That is, as a fluorine-based compound, it is used in combination with three R 3 The R located in the center of the main chain3 Precursor compound 11e was prepared in the same manner as precursor compound 11d except that a fluorine-based compound having a hydroxymethyl group was disposed at each end of the corresponding perfluoropolyether chain. 3 The R located in the center of the main chain 3 The corresponding perfluoropolyether chain has two ends with R 4 The main chain portion corresponds to the epoxy group.

[0300] Precursor compounds 11b and 11c were prepared in the same manner as in the second preparation method. Furthermore, the hydroxyl group of the hydroxymethyl group disposed at one end of the precursor compound 11b and the R-containing group disposed at one end of the precursor compound 11e were fused. 4 The first intermediate compound 1f is prepared by reacting the obtained reaction product with the hydroxyl group of the hydroxymethyl group disposed at one end of the precursor compound 11c. Alternatively, the precursor compound 11e may be reacted with the precursor compound 11c, and then the obtained reaction product may be reacted with the precursor compound 11b. In the first intermediate compound 1f, the two 4 The groups corresponding to the main chain portion are each provided with a secondary hydroxyl group generated by the reaction of the hydroxyl group of the hydroxymethyl group with the epoxy group.

[0301] <2 R 4 Different situations>

[0302] In the manufacturing formula (1), x is 2 and 3 R 3 Same, R 1 With R 6 Same, 2 R 4 In the case of different compounds, replace the 3 The corresponding perfluoropolyether chain has two ends with R 4 The first intermediate compound 1e was produced by using the precursor compound 11d having an epoxy group corresponding to the main chain portion of , and using the precursor compound 11f shown below.

[0303] In addition, when x in the manufacturing formula (1) is 2 and 3 R 3 Some or all of them are different, and / or R 1 With R 6 Different, 2 R 4 In the case of different compounds, replace the 3 R 3 The R located in the center of the main chain 3 The corresponding perfluoropolyether chain has two ends with R 4The first intermediate compound 1f is produced by using the precursor compound 11e having an epoxy group corresponding to the main chain portion of , and using the precursor compound 11f shown below.

[0304] Precursor compound 11f can be prepared by the following method. 3 (3 R 3 If some or all of them are different, the three R 3 The R located in the center of the main chain 3 ) are provided with a fluoro compound having a hydroxymethyl group at both ends of the corresponding perfluoropolyether chain. The hydroxyl group of the hydroxymethyl group provided at one end of the fluoro compound is connected to R 1 Side R 4 Then, the hydroxyl group of the hydroxymethyl group disposed at the other end of the fluorine-based compound is reacted with the halogen compound having an epoxy group corresponding to the main chain portion of R 6 Side R 4 The halogen compound having an epoxy group corresponding to the main chain portion is reacted.

[0305] Thus, we can obtain 3 (In 3 R 3 If some or all of the three Rs are different, 3 The R located in the center of the main chain 3 ) The two ends of the corresponding perfluoropolyether chain have different R 4 The precursor compound 11f of the epoxy group corresponding to the main chain part of R. 1 Side R 4 The halogen compound having an epoxy group corresponding to the main chain portion of R 6 Side R 4 Any of the halogen compounds having an epoxy group corresponding to the main chain portion of may be placed first.

[0306] As the first reaction step of the third production method, 1 Side R 4 and R 6 Side R 4 The halogen compound having an epoxy group corresponding to the main chain portion of 4 The main chain portion thereof corresponds to the same halogen compound as the halogen compound having an epoxy group.

[0307] As above with R 1 Side R 4 The main chain portion of the corresponding halogen compound having an epoxy group, for example, in R 1 Side R4 In the formula (3-1), when y1 is 1 and y2 is 2, or when R 1 Side R 4 In the formula (3-2), when y3 is 1 and y4 is 2, 2-chloroethyl oxirane and 2-bromoethyl oxirane can be used. 1 Side R 4 It is represented by formula (3-1), when y1 is 1 and y2 is 3, or, in R 1 Side R 4 In the formula (3-2), when y3 in the formula (3-2) is 1 and y4 is 3, 3-chloropropyl oxirane and 3-bromopropyl oxirane can be used.

[0308] As above with R 6 Side R 4 The main chain portion of the corresponding halogen compound having an epoxy group, for example, in R 6 Side R 4 In the formula (3-1), when y1 is 2 and y2 is 1, or when R 6 Side R 4 In the formula (3-2), when y3 is 2 and y4 is 1, 2-chloroethyl oxirane and 2-bromoethyl oxirane can be used. 6 Side R 4 In the formula (3-1), when y1 is 3 and y2 is 1, or when R 6 Side R 4 In the case where y3 is 3 and y4 is 1 and represented by the formula (3-2), 3-chloropropyl oxirane and 3-bromopropyl oxirane can be used.

[0309] (Second Reaction Step)

[0310] <R 2 The side chain part and 2 R 4 The side chain part of R 5 When the side chain parts are the same>

[0311] In the manufacturing formula (1), x is 2, and R 2 The side chain part and 2 R 4 The side chain part of R 5 In the case of a fluorinated ether compound having the same side chain moiety as R in formula (1), in the second reaction step, 2 The side chain part (=2 R 4 The side chain part and R 5A halide having a protected hydroxyl group corresponding to the side chain portion of the first intermediate compound 1e or the secondary hydroxyl group of the first intermediate compound 1f produced by the first reaction step reacts to produce a second intermediate compound 2e.

[0312] <R 2 The side chain part and 2 R 4 The side chain part of R 5 When part or all of the side chain parts of are different>

[0313] In the manufacturing formula (1), x is 2, and R 2 The side chain part and 2 R 4 The side chain part of R 5 In the case of a fluorine-containing ether compound having a part or all of a different side chain portion, in the second reaction step, R 2 , 2 R 4 and R 5 The halide having a protected hydroxyl group corresponding to each side chain part of the first intermediate compound 1e or the secondary hydroxyl group of the first intermediate compound 1f produced by the first reaction step is reacted in sequence using a known method to produce the second intermediate compound 2f. After the reaction, it is purified by a known method such as column chromatography as needed to obtain a second intermediate compound 2f having R 2 The side chain part, 2 R 4 The side chain part and R 5 The side chain of the second intermediate compound 2f is made by reacting with R 2 , 2 R 4 and R 5 The order in which the halide having a protected hydroxyl group corresponding to each side chain portion of is reacted with the first intermediate compound 1e or the first intermediate compound 1f is not particularly limited.

[0314] As the compound used in the second reaction step of the third production method, 2 , 2 R 4 and R 5 The halides having protected hydroxyl groups corresponding to the side chain portions of can be, for example, the halides which can be used in the second production method and which are compatible with R in formula (1) 2 , R 4 and R 5 The halide having a protected hydroxyl group corresponding to each side chain portion is the same halide.

[0315] Next, a deprotection reaction is performed to remove the protecting group derived from the halide having the protected hydroxyl group possessed by the second intermediate compound 2e or the second intermediate compound 2f by a known method corresponding to the type of the protecting group. 2 The side chain part, 2 R 4 The side chain part and R 5 One primary hydroxyl group is respectively arranged at the front end of the side chain portion.

[0316] By carrying out the above steps, a fluorine-containing ether compound wherein x in the formula (1) is 2 is obtained.

[0317] [Lubricant for magnetic recording media]

[0318] The lubricant for magnetic recording media according to the present embodiment contains the fluorine-containing ether compound represented by the above formula (1).

[0319] The lubricant of the present embodiment may be mixed with a known material used as a lubricant material as necessary, as long as the properties due to the fluorine-containing ether compound represented by the above formula (1) are not impaired.

[0320] Specific examples of known materials include FOMBLIN (registered trademark) ZDIAC, FOMBLIN ZDEAL, FOMBLIN AM-2001 (all manufactured by Solvay Solexis), Moresco A20H (manufactured by Moresco), etc. The known material used in combination with the lubricant of the present embodiment preferably has a number average molecular weight of 1,000 to 10,000.

[0321] When the lubricant of the present embodiment contains a material other than the fluorinated ether compound represented by the above formula (1), the content of the fluorinated ether compound represented by the above formula (1) in the lubricant of the present embodiment is preferably 50% by mass or more, more preferably 70% by mass or more.

[0322] Since the lubricant of the present embodiment contains the fluorine-containing ether compound represented by the above formula (1), it is possible to form a lubricating layer having excellent chemical resistance and a high pickup suppression effect.

[0323] [Magnetic recording media]

[0324] The magnetic recording medium of this embodiment includes at least a magnetic layer, a protective layer, and a lubricating layer provided in this order on a substrate.

[0325] In the magnetic recording medium of this embodiment, one or more underlayers may be provided between the substrate and the magnetic layer as required. In addition, at least one of an adhesion layer and a soft magnetic layer may be provided between the underlayer and the substrate.

[0326] Figure 1 This is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.

[0327] The magnetic recording medium 10 of the present embodiment has a structure in which an adhesion layer 12 , a soft magnetic layer 13 , a first underlayer 14 , a second underlayer 15 , a magnetic layer 16 , a protective layer 17 , and a lubricating layer 18 are sequentially provided on a substrate 11 .

[0328] "Substrate"

[0329] As the substrate 11 , for example, a non-magnetic substrate in which a film made of NiP or a NiP alloy is formed on a base made of a metal or alloy material such as Al or an Al alloy can be used.

[0330] In addition, as the substrate 11, a non-magnetic substrate formed of a non-metallic material such as glass, ceramics, silicon, silicon carbide, carbon, or resin can be used, or a non-magnetic substrate having a film of NiP or NiP alloy formed on a base formed of these non-metallic materials can be used.

[0331] "Attachment Layer"

[0332] The adhesion layer 12 prevents the substrate 11 from being corroded when the substrate 11 and the soft magnetic layer 13 provided on the adhesion layer 12 are arranged in contact with each other.

[0333] The material of the adhesion layer 12 can be appropriately selected from, for example, Cr, Cr alloy, Ti, Ti alloy, CrTi, NiAl, AlRu alloy, etc. The adhesion layer 12 can be formed by, for example, sputtering.

[0334] "Soft magnetic layer"

[0335] The soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer including a Ru film, and a second soft magnetic film are stacked in sequence. That is, the soft magnetic layer 13 preferably has a structure in which the upper and lower soft magnetic films of the intermediate layer are antiferrocoupled (AFC) by sandwiching the intermediate layer including a Ru film between the two soft magnetic films.

[0336] Examples of the material of the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy.

[0337] Preferably, any one of Zr, Ta, and Nb is added to the CoFe alloy used for the first soft magnetic film and the second soft magnetic film. This promotes the amorphization of the first soft magnetic film and the second soft magnetic film. As a result, the orientation of the first base layer (seed layer) can be improved, and the floating amount of the magnetic head can be reduced.

[0338] The soft magnetic layer 13 can be formed by, for example, sputtering.

[0339] "1st base layer"

[0340] The first underlayer 14 is a layer for controlling the orientation and crystal size of the second underlayer 15 and the magnetic layer 16 provided thereon.

[0341] Examples of the first base layer 14 include a Cr layer, a Ta layer, a Ru layer, a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, a CrTi alloy layer, and the like.

[0342] The first base layer 14 can be formed by, for example, sputtering.

[0343] "Second base layer"

[0344] The second underlayer 15 is a layer controlled so as to improve the orientation of the magnetic layer 16. The second underlayer 15 is preferably a layer formed of Ru or a Ru alloy.

[0345] The second base layer 15 may be composed of a single layer or a plurality of layers. When the second base layer 15 is composed of a plurality of layers, all layers may be composed of the same material, or at least one layer may be composed of a different material.

[0346] The second base layer 15 can be formed by, for example, sputtering.

[0347] "Magnetic layer"

[0348] The magnetic layer 16 is made of a magnetic film whose easy magnetization axis is oriented vertically or horizontally with respect to the substrate surface. The magnetic layer 16 is a layer containing Co and Pt. In order to improve the SNR characteristics, the magnetic layer 16 may be a layer containing oxide, Cr, B, Cu, Ta, Zr, etc.

[0349] Examples of the oxide contained in the magnetic layer 16 include SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 , and TiO 2 .

[0350] The magnetic layer 16 may be composed of a single layer or a plurality of magnetic layers formed of materials having different compositions.

[0351] For example, when the magnetic layer 16 is composed of three layers, namely, the first magnetic layer, the second magnetic layer, and the third magnetic layer, which are stacked in order from the bottom, the first magnetic layer is preferably a granular structure formed by a material containing Co, Cr, Pt, and further containing an oxide. As the oxide contained in the first magnetic layer, it is preferred to use, for example, oxides of Cr, Si, Ta, Al, Ti, Mg, Co, etc. Among them, TiO2, Cr2O3, SiO2, etc. can be particularly suitable. In addition, the first magnetic layer is preferably formed by a composite oxide to which two or more oxides are added. Among them, Cr2O3-SiO2, Cr2O3-TiO2, SiO2-TiO2, etc. can be particularly suitable.

[0352] The first magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides. The second magnetic layer may contain the same material as the first magnetic layer. The second magnetic layer preferably has a granular structure.

[0353] The third magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, and Pt and containing no oxide. In addition to Co, Cr, and Pt, the third magnetic layer may contain one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn.

[0354] When the magnetic layer 16 is formed of a plurality of magnetic layers, a non-magnetic layer is preferably provided between adjacent magnetic layers. When the magnetic layer 16 is composed of three layers, namely, a first magnetic layer, a second magnetic layer, and a third magnetic layer, a non-magnetic layer is preferably provided between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer.

[0355] The non-magnetic layer arranged between adjacent magnetic layers of the magnetic layer 16 can be suitably made of, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 represents one or more elements selected from Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Ti, V, and B), etc.

[0356] In the non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16, an alloy material containing oxide, metal nitride, or metal carbide is preferably used. Specifically, as oxides, for example, SiO2, Al2O3, Ta2O5, Cr2O3, MgO, Y2O3, TiO2, etc. can be used. As metal nitrides, for example, AlN, Si3N4, TaN, CrN, etc. can be used. As metal carbides, for example, TaC, BC, SiC, etc. can be used.

[0357] The non-magnetic layer can be formed by, for example, sputtering.

[0358] In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer with its easy magnetization axis oriented perpendicularly to the substrate surface. The magnetic layer 16 may be an in-plane magnetic recording magnetic layer.

[0359] The magnetic layer 16 can be formed by any conventionally known method such as vapor deposition, ion beam sputtering, magnetron sputtering, etc. The magnetic layer 16 is usually formed by sputtering.

[0360] "Protective layer"

[0361] The protective layer 17 protects the magnetic layer 16. The protective layer 17 may be composed of one layer or multiple layers. As the protective layer 17, a carbon-based protective layer may be preferably used, and an amorphous carbon protective layer is particularly preferred. If the protective layer 17 is a carbon-based protective layer, the interaction with the polar group (especially hydroxyl group) contained in the fluorine-containing ether compound in the lubricating layer 18 is further improved, so it is preferred.

[0362] The adhesion between the carbon-based protective layer and the lubricating layer 18 can be controlled by making the carbon-based protective layer hydrogenated carbon and / or carbon nitride and adjusting the hydrogen content and / or nitrogen content in the carbon-based protective layer. The hydrogen content in the carbon-based protective layer is preferably 3 atomic % to 20 atomic % when measured by hydrogen forward scattering (HFS). In addition, the nitrogen content in the carbon-based protective layer is preferably 4 atomic % to 15 atomic % when measured by X-ray photoelectron spectroscopy (XPS).

[0363] The hydrogen and / or nitrogen contained in the carbon-based protective layer does not need to be uniformly contained in the entire carbon-based protective layer. For example, the carbon-based protective layer is preferably formed into a composition gradient layer in which nitrogen is contained on the lubricating layer 18 side of the protective layer 17 and hydrogen is contained on the magnetic layer 16 side of the protective layer 17. In this case, the adhesion between the magnetic layer 16 and the lubricating layer 18 and the carbon-based protective layer is further improved.

[0364] The protective layer 17 preferably has a thickness of 1 nm to 7 nm. When the protective layer 17 has a thickness of 1 nm or more, sufficient performance as the protective layer 17 can be obtained. When the protective layer 17 has a thickness of 7 nm or less, this is preferred from the viewpoint of reducing the thickness of the protective layer 17.

[0365] As a method for forming the protective layer 17 , a sputtering method using a target containing carbon, a CVD (chemical vapor deposition) method using a hydrocarbon raw material such as ethylene or toluene, an IBD (ion beam deposition) method, or the like can be used.

[0366] When a carbon-based protective layer is formed as the protective layer 17, for example, a film can be formed by a DC magnetron sputtering method. In particular, when a carbon-based protective layer is formed as the protective layer 17, it is preferable to form an amorphous carbon protective layer by a plasma CVD method. The surface of the amorphous carbon protective layer formed by the plasma CVD method is uniform and has little roughness.

[0367] "Lubricating layer"

[0368] The lubricating layer 18 prevents contamination of the magnetic recording medium 10. In addition, the lubricating layer 18 reduces the frictional force of the magnetic head of the magnetic recording and reproducing device sliding on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10.

[0369] like Figure 1 As shown, the lubricating layer 18 is formed in contact with the protective layer 17. The lubricating layer 18 is formed by applying the lubricant for a magnetic recording medium of the above-mentioned embodiment onto the protective layer 17. Therefore, the lubricating layer 18 contains the above-mentioned fluorine-containing ether compound.

[0370] When the protective layer 17 disposed under the lubricating layer 18 is a carbon-based protective layer, the lubricating layer 18 is particularly bonded with the protective layer 17 with a high bonding force. As a result, it is easy to obtain a magnetic recording medium 10 in which the surface of the protective layer 17 is coated with a high coverage rate even if the thickness of the lubricating layer 18 is thin, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented.

[0371] The average film thickness of the lubricating layer 18 is preferably More preferably If the average film thickness of the lubricating layer 18 is more than 0.5nm, the lubricating layer 18 is not island-shaped or mesh-shaped but is formed with uniform film thickness. Therefore, the surface of the protective layer 17 can be coated with a high coverage rate by the lubricating layer 18. In addition, by making the average film thickness of the lubricating layer 18 less than 2.0nm, the lubricating layer 18 can be fully filmized, and the floating amount of the magnetic head can be fully reduced.

[0372] "Method for forming a lubricating layer"

[0373] The lubricating layer 18 may be formed by, for example, preparing a magnetic recording medium in the process of production in which each layer up to the protective layer 17 is formed on the substrate 11 , and applying a lubricating layer forming solution on the protective layer 17 .

[0374] The lubricant layer-forming solution is obtained by dispersing and dissolving the lubricant for a magnetic recording medium of the above-described embodiment in a solvent as necessary to obtain a viscosity and a concentration suitable for a coating method.

[0375] Examples of the solvent used for the lubricating layer-forming solution include fluorine-based solvents such as Batler (registered trademark) XF (trade name, manufactured by DuPont Mitsui Fluoro Chemical Co., Ltd.).

[0376] The coating method of the lubricating layer forming solution is not particularly limited, and examples thereof include a spin coating method, a spray method, a paper coating method, and a dipping method.

[0377] When the dipping method is used, for example, the following method can be used. First, the substrate 11 on which each layer up to the protective layer 17 is formed is dipped in the lubricating layer forming solution placed in the dipping tank of the dipping coating device. Next, the substrate 11 is pulled out of the dipping tank at a predetermined speed. Thus, the lubricating layer forming solution is applied to the surface of the substrate 11 on the protective layer 17.

[0378] 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.

[0379] 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 the heat treatment, the adhesion between the lubricating layer 18 and the protective layer 17 is improved, and the adhesion between the lubricating layer 18 and the protective layer 17 is improved.

[0380] The heat treatment temperature is preferably 100° C. to 180° C., and more preferably 100° C. to 160° C. If the heat treatment temperature is 100° C. or higher, the effect of improving the adhesion between the lubricating layer 18 and the protective layer 17 is sufficiently obtained. In addition, by setting the heat treatment temperature to 180° C. or lower, thermal decomposition of the lubricating layer 18 caused by the heat treatment can be prevented. The heat treatment time can be appropriately adjusted according to the heat treatment temperature, and is preferably 10 minutes to 120 minutes.

[0381] In the present embodiment, in order to further improve the adhesion of the lubricating layer 18 to the protective layer 17 , the lubricating layer 18 may be irradiated with ultraviolet light (UV) before or after the heat treatment.

[0382] The magnetic recording medium 10 of the present embodiment has at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 sequentially arranged on a substrate 11. For the magnetic recording medium 10 of the present embodiment, a lubricating layer 18 containing the above-mentioned fluorine-containing ether compound is formed in contact with the protective layer 17. The lubricating layer 18 has good chemical resistance and a good pickup suppression effect. Therefore, the magnetic recording medium 10 of the present embodiment is excellent in reliability, especially in the suppression of silicon contamination and durability. Therefore, the magnetic recording medium 10 of the present embodiment can make the head floating amount low (for example, less than 10nm), and operate stably for a long time even in a harsh environment with a variety of uses. Therefore, the magnetic recording medium 10 of the present embodiment is particularly suitable as a magnetic disk mounted on a magnetic disk device of the LUL (LoadUnload) method.

[0383] Example

[0384] Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. In addition, the present invention is not limited to the following Examples.

[0385] [Example 1]

[0386] The compound represented by the above formula (A) was obtained by the method shown below.

[0387] (First Reaction Step)

[0388] In a 100 mL eggplant flask under nitrogen atmosphere, add HOCH2CF2O (CF2CF2O) h (CF2O) i 10 g of a compound represented by CF2CH2OH (wherein h represents the average degree of polymerization and i represents the average degree of polymerization, respectively) (number average molecular weight 1000, molecular weight distribution 1.1), 4.75 g of a compound represented by the above formula (7-1), and 20 mL of tert-butyl alcohol were stirred at room temperature until the mixture became uniform to prepare a mixture. 0.90 g of potassium tert-butylate was added to the mixture, and the mixture was stirred at 70°C for 16 hours to react.

[0389] The compound represented by formula (7-1) is synthesized by protecting the hydroxyl group of 3-buten-1-ol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0390] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel to which 100 mL of water was added, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 11.31 g of the compound represented by the following formula (9) as the first intermediate compound.

[0391]

[0392] (Rf1 in formula (9) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0393] (Second Reaction Step)

[0394] Next, 11.31 g of the compound represented by formula (9) obtained as the first intermediate compound, 4.09 g of the compound represented by formula (8-1) (2-(2-bromoethoxy)tetrahydro-2H-pyran), and 20 mL of dimethylformamide were added to a 100 mL eggplant flask under a nitrogen atmosphere, and stirred at room temperature until the mixture became uniform. 0.78 g of sodium hydride was added to the uniform liquid, and the mixture was stirred at 40° C. for 16 hours to react.

[0395] The reaction solution obtained after the reaction was returned to room temperature, 5 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine in this order, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 4.15 g of compound (A) (Rf1 in formula (A) is the PFPE chain shown in the above formula (4-1). In Rf1, h representing the average degree of polymerization represents 4.5, and i representing the average degree of polymerization represents 4.5.).

[0396] The obtained compound (A) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0397] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (22H), 3.85-4.10 (4H)

[0398] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0399] [Example 2]

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

[0401] Instead of the compound represented by formula (7-1), the compound represented by formula (7-2) was used. Except for this, the same operation as in Example 1 was carried out to obtain 4.02 g of compound (B) (Rf1 in formula (B) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0402] The compound represented by formula (7-2) can be synthesized by protecting the hydroxyl group of allyl alcohol with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0403] The obtained compound (B) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0404] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (22H), 3.85-4.10 (4H)

[0405] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0406] [Example 3]

[0407] The compound represented by the above formula (C) was obtained by the method shown below.

[0408] Instead of the compound represented by formula (7-1), the compound represented by formula (7-3) was used. Except for this, the same operations as in Example 1 were carried out to obtain 4.81 g of compound (C) (Rf1 in formula (C) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0409] The compound represented by formula (7-3) can be synthesized by protecting the hydroxyl group of ethylene glycol monoallyl ether with dihydropyran and then oxidizing it with m-chloroperbenzoic acid.

[0410] The obtained compound (C) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0411] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (34H), 3.85-4.10 (4H)

[0412] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0413] [Example 4]

[0414] The compound represented by the above formula (D) was obtained by the method shown below.

[0415] Instead of the compound represented by formula (7-1), the compound represented by formula (7-4) was used. Except for this, the same operations as in Example 1 were carried out to obtain 5.21 g of compound (D) (Rf1 in formula (D) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.

[0416] The compound represented by formula (7-4) was synthesized by the following method: One hydroxyl group of ethylene glycol was protected with dihydropyran and then reacted with allyl glycidyl ether. The secondary hydroxyl group generated after the reaction was protected with chloromethyl methyl ether and then oxidized with m-chloroperbenzoic acid to synthesize the compound.

[0417] The obtained compound (D) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0418] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (34H), 3.85-4.10 (4H)

[0419] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0420] [Example 5]

[0421] The compound represented by the above formula (E) was obtained by the method shown below.

[0422] Instead of the compound represented by formula (7-1), the compound represented by formula (7-5) was used. Except for this, the same operations as in Example 1 were carried out to obtain 5.41 g of compound (E) (Rf1 in formula (E) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0423] The compound represented by formula (7-5) was synthesized by the following method: Epichlorohydrin was reacted with 2 times the molar amount of allyl alcohol, the secondary hydroxyl group generated after the reaction was protected with chloromethyl methyl ether, and one carbon-carbon double bond was oxidized with m-chloroperbenzoic acid to synthesize the compound.

[0424] The obtained compound (E) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0425] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (36H), 3.85-4.10 (4H), 5.2-6.1 (6H)

[0426] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0427] [Example 6]

[0428] The compound represented by the above formula (F) was obtained by the method shown below.

[0429] Instead of the compound represented by formula (7-1), the compound represented by formula (7-6) was used. The same operations as in Example 1 were carried out to obtain 5.82 g of compound (F) (Rf1 in formula (F) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0430] The compound represented by formula (7-6) was synthesized by the following method: Phenol was reacted with allyl glycidyl ether, and the secondary hydroxyl group generated after the reaction was protected with chloromethyl methyl ether and oxidized with m-chloroperbenzoic acid to synthesize the compound.

[0431] The obtained compound (F) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0432] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (32H), 3.85-4.10 (4H), 6.8-7.6 ppm (10H)

[0433] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0434] [Example 7]

[0435] The compound represented by the above formula (G) was obtained by the method shown below.

[0436] Instead of the compound represented by formula (7-1), the compound represented by formula (7-7) was used. Except for this, the same operation as in Example 1 was carried out to obtain 4.61 g of compound (G) (Rf1 in formula (G) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0437] The compound represented by formula (7-7) is synthesized by reacting 3-cyanopropanol with epibromohydrin.

[0438] The obtained compound (G) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0439] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 2.00-2.10 (4H), 3.40-3.85 (24H), 3.85-4.10 (4H)

[0440] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0441] [Example 8]

[0442] The compound represented by the above formula (H) was obtained by the method shown below.

[0443] Instead of the compound represented by formula (7-1), the compound represented by formula (7-8) was used. Except for this, the same operations as in Example 1 were carried out to obtain 4.33 g of compound (H) (Rf1 in formula (H) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0444] The compound represented by formula (7-8) is synthesized by reacting acetylaminoethanol with epibromohydrin.

[0445] The obtained compound (H) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0446] 1 H-NMR (acetone-D6): δ [ppm] = 1.90-2.00 (6H), 3.40-3.85 (24H), 3.85-4.10 (4H), 6.30-6.40 (2H)

[0447] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0448] [Example 9]

[0449] The compound represented by the above formula (I) was obtained by the method shown below.

[0450] The same operation as in Example 1 was performed except that the compound represented by formula (8-2) was used instead of the compound represented by formula (8-1), thereby obtaining 4.18 g of compound (I) (Rf1 in formula (I) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0451] The compound represented by formula (8-2) is synthesized by protecting the hydroxyl group of 3-bromopropanol with dihydropyran.

[0452] The obtained compound (I) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0453] 1H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (8H), 3.45-3.85 (22H), 3.85-4.10 (4H)

[0454] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0455] [Example 10]

[0456] The compound represented by the above formula (J) was obtained by the method shown below.

[0457] Instead of the compound represented by formula (8-1), the compound represented by formula (8-3) was used. Except for this, the same operations as in Example 1 were carried out to obtain 4.36 g of compound (J) (Rf1 in formula (J) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0458] The compound represented by formula (8-3) is synthesized by protecting the hydroxyl group of 4-bromobutanol with dihydropyran.

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

[0460] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (12H), 3.45-3.85 (22H), 3.85-4.10 (4H)

[0461] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0462] [Example 11]

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

[0464] Instead of the compound represented by formula (8-1), the compound represented by formula (8-4) was used. Except for this, the same operations as in Example 1 were carried out to obtain 4.54 g of compound (K) (Rf1 in formula (K) is the PFPE chain represented by the above formula (4-1). In Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0465] The compound represented by formula (8-4) is synthesized by brominating one hydroxyl group of diethylene glycol with phosphorus tribromide and then protecting the other hydroxyl group with dihydropyran.

[0466] The obtained compound (K) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0467] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.45-3.85 (30H), 3.85-4.10 (4H)

[0468] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (9F), -78.5 (2F), -80.5 (2F), -91.0 to -88.5 (18F)

[0469] [Example 12]

[0470] The compound represented by the above formula (L) was obtained by the method shown below.

[0471] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2O (CF2CF2CF2O). j A compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) was obtained by the same operation as in Example 1 to obtain 4.26 g of compound (L) (Rf2 in formula (L) is the PFPE chain represented by the above formula (4-2). In Rf2, j representing the average degree of polymerization is 4.5).

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

[0473] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.45-3.85 (30H), 3.85-4.10 (4H)

[0474] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (18F), -86.4 (4F), -124.3 (4F), -130.0 to -129.0 (9F)

[0475] [Example 13]

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

[0477] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2CF2O (CF2CF2CF2CF2O). k A compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CF2CH2OH (where k representing the average degree of polymerization is 3.0) was obtained by performing the same operations as in Example 1 to obtain 4.10 g of compound (M) (Rf3 in formula (M) is the PFPE chain represented by the above formula (4-3). In Rf3, k representing the average degree of polymerization is 3.0).

[0478] The obtained compound (M) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0479] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.45-3.85 (30H), 3.85-4.10 (4H)

[0480] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (16F), -122.5 (4F), -126.0 (12F), -129.0 to -128.0 (4F)

[0481] [Example 14]

[0482] The compound represented by the above formula (N) was obtained by the method shown below.

[0483] (First Reaction Step)

[0484] In a 100 mL eggplant flask under nitrogen atmosphere, add HOCH2CF2O (CF2CF2O) h (CF2O) i 20 g of a compound represented by CF2CH2OH (wherein h represents the average degree of polymerization and i represents the average degree of polymerization, respectively) (number average molecular weight 1000, molecular weight distribution 1.1), 2.06 g of a compound represented by the above formula (7-1), and 20 mL of tert-butyl alcohol were stirred at room temperature until the mixture became uniform to prepare a mixture. 0.90 g of potassium tert-butylate was added to the mixture, and the mixture was stirred at 70°C for 16 hours to react.

[0485] The reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel to which 100 mL of water was added, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated with anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 8.41 g of the compound represented by the following formula (10) as a precursor compound.

[0486]

[0487] (Rf1 in formula (10) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0488] In a 100 mL eggplant flask under a nitrogen atmosphere, 8.41 g of the compound represented by formula (10) obtained above as a precursor compound, 0.88 g of epibromohydrin, and 10 mL of tert-butyl alcohol were added and stirred at room temperature until the mixture became homogeneous. 0.96 g of potassium tert-butylate was added to the homogeneous liquid and the mixture was stirred at 70° C. for 23 hours to react.

[0489] The reaction solution obtained after the reaction was returned to room temperature, transferred to a separatory funnel to which 100 mL of water was added, and extracted 3 times with 100 mL of ethyl acetate. The organic layer was washed with water and dehydrated by anhydrous sodium sulfate. After filtering and separating the desiccant, the filtrate was concentrated, and the residue was refined by silica gel column chromatography to obtain 5.61 g of the compound shown in the following formula (11) as the first intermediate compound.

[0490]

[0491] (Rf1 in formula (11) is the PFPE chain represented by the above formula (4-1); in the two Rf1s, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0492] (Second Reaction Step)

[0493] In a 100 mL eggplant flask under a nitrogen atmosphere, 5.61 g of the compound represented by formula (11) obtained as the first intermediate compound, 4.18 g of the compound represented by formula (8-1), and 20 mL of dimethylformamide were added and stirred at room temperature until the mixture became homogeneous. 0.85 g of sodium hydride was added to the homogeneous liquid and the mixture was stirred at 40° C. for 16 hours to react.

[0494] The reaction solution obtained after the reaction was returned to room temperature, 5 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine in this order, and dehydrated with anhydrous sodium sulfate. After the desiccant was filtered and separated, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 2.45 g of compound (N) (Rf1 in formula (N) is the PFPE chain shown in the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0495] The obtained compound (N) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0496] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (32H), 3.85-4.10 (8H)

[0497] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0498] [Example 15]

[0499] The compound represented by the above formula (O) was obtained by the method shown below.

[0500] Instead of the compound represented by formula (7-1), the compound represented by formula (7-3) was used. Except for this, the same operation as in Example 14 was carried out to obtain 2.68 g of compound (O) (Rf1 in formula (O) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0501] The obtained compound (O) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0502] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (44H), 3.85-4.10 (8H)

[0503] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0504] [Example 16]

[0505] The compound represented by the above formula (P) was obtained by the method shown below.

[0506] Instead of the compound represented by formula (7-1), the compound represented by formula (7-7) was used. Except for this, the same operation as in Example 14 was carried out to obtain 2.64 g of compound (P) (Rf1 in formula (P) is the PFPE chain represented by the above formula (4-1). Among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

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

[0508] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 2.00-2.10 (4H), 3.40-3.85 (34H), 3.85-4.10 (8H)

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

[0510] [Example 17]

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

[0512] Instead of the compound represented by formula (8-1), the compound represented by formula (8-2) was used. Except for this, the same operations as in Example 14 were carried out to obtain 2.52 g of compound (Q) (Rf1 in formula (Q) is the PFPE chain represented by the above formula (4-1); among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

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

[0514] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (10H), 3.40-3.85 (32H), 3.85-4.10 (8H)

[0515] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0516] [Example 18]

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

[0518] Instead of the compound represented by formula (8-1), the compound represented by formula (8-4) was used. Except for this, the same operations as in Example 14 were carried out to obtain 2.52 g of compound (R) (Rf1 in formula (R) is the PFPE chain represented by the above formula (4-1); among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0519] The obtained compound (R) is 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0520] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (44H), 3.85-4.10 (8H)

[0521] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0522] [Example 19]

[0523] The compound represented by the above formula (S) was obtained by the method shown below.

[0524] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2O (CF2CF2CF2O). j A compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) was obtained by the same operation as in Example 14 to obtain 2.18 g of compound (S) (Rf2 in formula (S) is the PFPE chain represented by the above formula (4-2); among the two Rf2, j representing the average degree of polymerization is 4.5).

[0525] The obtained compound (S) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0526] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (32H), 3.85-4.10 (8H)

[0527] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (36F), -86.4 (8F), -124.3 (8F), -130.0 to -129.0 (18F)

[0528] [Example 20]

[0529] The compound represented by the above formula (T) was obtained by the method shown below.

[0530] (First Reaction Step)

[0531] In the same manner as in Example 14, a compound represented by formula (10) was obtained as a precursor compound.

[0532] Furthermore, the same operation as in Example 14 was carried out except that the compound represented by formula (12) was used instead of epibromohydrin in the reaction for obtaining the first intermediate compound in Example 14 to obtain 7.81 g of the compound represented by the following formula (13) as the first intermediate compound.

[0533] The compound represented by formula (12) is prepared by making HOCH2CF2O(CF2CF2O) h (CF2O) i The synthesis was carried out by reacting a compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CH2OH (wherein h representing the average polymerization degree is 4.5, and i representing the average polymerization degree is 4.5) with epibromohydrin.

[0534]

[0535] (Rf1 in formula (12) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0536]

[0537] (Rf1 in formula (13) is the PFPE chain represented by the above formula (4-1); among the three Rf1, h representing the average degree of polymerization is 4.5, i representing the average degree of polymerization is 4.5; THP represents tetrahydropyranyl.)

[0538] (Second Reaction Step)

[0539] In a 100 mL eggplant flask under a nitrogen atmosphere, 7.81 g of the compound represented by formula (13) obtained as the first intermediate compound, 6.32 g of the compound represented by formula (8-1), and 20 mL of dimethylformamide were added and stirred at room temperature until the mixture became homogeneous. 1.08 g of sodium hydride was added to the homogeneous liquid and the mixture was stirred at 40° C. for 16 hours to react.

[0540] The reaction solution obtained after the reaction was returned to room temperature, 5 g of 10% hydrogen chloride / methanol solution (hydrogen chloride-methanol reagent (5-10%) manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and stirred at room temperature for 4 hours. Then, the reaction solution was transferred little by little to a separatory funnel added with 100 mL of saturated sodium bicarbonate water, and extracted twice with 200 mL of ethyl acetate. The organic layer was washed with 100 mL of brine, 100 mL of saturated sodium bicarbonate water, and 100 mL of brine in this order, and dehydrated with anhydrous sodium sulfate. After the desiccant was separated by filtration, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 2.71 g of compound (T) (Rf1 in formula (T) is the PFPE chain shown in the above formula (4-1). Among the three Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0541] The obtained compound (T) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0542] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (42H), 3.85-4.10 (12H)

[0543] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0544] [Example 21]

[0545] The compound represented by the above formula (U) was obtained by the method shown below.

[0546] Instead of using the compound represented by formula (7-1), the compound represented by formula (7-3) was used. Except for this, the same operations as in Example 20 were performed to obtain 2.68 g of compound (U) (Rf1 in formula (U) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

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

[0548] 1H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (54H), 3.85-4.10 (12H)

[0549] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0550] [Example 22]

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

[0552] Instead of the compound represented by formula (7-1), the compound represented by formula (7-7) was used. Except for this, the same operation as in Example 20 was performed to obtain 2.92 g of compound (V) (Rf1 in formula (V) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0553] The obtained compound (V) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0554] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 2.00-2.10 (4H), 3.40-3.85 (44H), 3.85-4.10 (12H)

[0555] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0556] [Example 23]

[0557] The compound represented by the above formula (W) was obtained by the method shown below.

[0558] Instead of the compound represented by formula (8-1), the compound represented by formula (8-4) was used. Except for this, the same operations as in Example 20 were performed to obtain 2.74 g of compound (W) (Rf1 in formula (W) is the PFPE chain represented by the above formula (4-1). Among the three Rf1s, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0559] The obtained compound (W) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0560] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (54H), 3.85-4.10 (12H)

[0561] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (27F), -78.5 (6F), -80.5 (6F), -91.0 to -88.5 (54F)

[0562] [Example 24]

[0563] The compound represented by the above formula (X) was obtained by the method shown below.

[0564] Replace HOCH2CF2O(CF2CF2O) h (CF2O) i The compound shown in CF2CH2OH is used instead of HOCH2CF2CF2O (CF2CF2CF2O). j A compound (number average molecular weight 1000, molecular weight distribution 1.1) represented by CF2CF2CH2OH (wherein j representing the average degree of polymerization is 4.5) was obtained by performing the same operations as in Example 20 to obtain 2.58 g of compound (X) (Rf2 in formula (X) is the PFPE chain represented by the above formula (4-2); among the three Rf2s, j representing the average degree of polymerization is 4.5).

[0565] The obtained compound (X) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0566] 1 H-NMR (acetone-D6): δ [ppm] = 1.60-1.80 (4H), 3.40-3.85 (42H), 3.85-4.10 (12H)

[0567] 19 F-NMR (acetone-D6): δ [ppm] = -84.0 to -83.0 (54F), -86.4 (12F), -124.3 (12F), -130.0 to -129.0 (27F)

[0568] [Example 25]

[0569] The compound represented by the above formula (XX) was obtained by the method shown below.

[0570] Instead of using the compound represented by formula (7-1), the compound represented by formula (7-2) was used. Except for this, the same operations as in Example 14 were carried out to obtain 2.45 g of compound (XX) (Rf1 in formula (XX) is the PFPE chain represented by the above formula (4-1); among the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.).

[0571] The obtained compound (XX) is subjected to 1 H-NMR and 19 The structure was identified based on the following results from F-NMR measurement.

[0572] 1 H-NMR (acetone-D6): δ [ppm] = 3.40-3.85 (32H), 3.85-4.10 (8H)

[0573] 19 F-NMR (acetone-D6): δ [ppm] = -55.5 to -51.5 (18F), -78.5 (4F), -80.5 (4F), -91.0 to -88.5 (36F)

[0574] The values ​​of x, R, and R when the compounds (A) to (X) and (XX) of Examples 1 to 25 obtained in this manner are substituted into the formula (1) are: 1 , R 2 , R 3 , R 4 , R 5 , R 6 The structures of are shown in Tables 1 and 2.

[0575] Table 1

[0576]

[0577] Table 2

[0578]

[0579] [Comparative Example 1]

[0580] According to the method described in Patent Document 1, a compound represented by the following formula (Y) was synthesized.

[0581]

[0582] (Rf1 in formula (Y) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0583] [Comparative Example 2]

[0584] According to the method described in Patent Document 2, a compound represented by the following formula (Z) was synthesized.

[0585]

[0586] (Rf1 in formula (Z) is the PFPE chain represented by the above formula (4-1); in the two Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0587] [Comparative Example 3]

[0588] According to the method described in Patent Document 3, a compound represented by the following formula (AA) was synthesized.

[0589]

[0590] (Rf2 in formula (AA) is the PFPE chain represented by the above formula (4-2); among the two Rf2, j indicating the average degree of polymerization is 4.5.)

[0591] [Comparative Example 4]

[0592] According to the method described in Patent Document 3, a compound represented by the following formula (AB) was synthesized.

[0593]

[0594] (Rf2 in formula (AB) is the PFPE chain represented by formula (4-2) above; j, which represents the average degree of polymerization of the two Rf2, is 4.5.)

[0595] [Comparative Example 5]

[0596] According to the method described in Patent Document 4, a compound represented by the following formula (AC) was synthesized.

[0597]

[0598] (Rf1 in formula (AC) is the PFPE chain represented by the above formula (4-1); among the three Rf1, h representing the average degree of polymerization is 7.0, and i representing the average degree of polymerization is 0.)

[0599] [Comparative Example 6]

[0600] According to the method described in Patent Document 5, a compound represented by the following formula (AD) was synthesized.

[0601]

[0602] (Rf1 in formula (AD) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0603] [Comparative Example 7]

[0604] According to the method described in Patent Document 5, a compound represented by the following formula (AE) was synthesized.

[0605]

[0606] (Rf1 in formula (AE) is the PFPE chain represented by the above formula (4-1); in Rf1, h representing the average degree of polymerization is 4.5, and i representing the average degree of polymerization is 4.5.)

[0607] The number average molecular weight (Mn) of the compounds of Examples 1 to 25 and Comparative Examples 1 to 7 obtained in this manner was measured by the above-mentioned method. The results are shown in Tables 3 and 4.

[0608] Next, a lubricant layer forming solution was prepared by the method described below using the compounds obtained in Examples 1 to 25 and Comparative Examples 1 to 7. Furthermore, the lubricant layer of a magnetic recording medium was formed by the method described below using the obtained lubricant layer forming solution, thereby obtaining magnetic recording media of Examples 1 to 25 and Comparative Examples 1 to 7.

[0609] "Lubricating layer forming solution"

[0610] The compounds obtained in Examples 1 to 25 and Comparative Examples 1 to 7 were dissolved in a fluorine-based solvent, Batorel (registered trademark) XF (trade name, manufactured by Mitsui Dupont Fluoro Chemical Co., Ltd.), respectively, to form a film with a thickness of 1000 Å when applied on the protective layer. The solution was diluted with Batler XF in a manner of 100% to prepare a lubricating layer forming solution.

[0611] "Magnetic recording media"

[0612] A magnetic recording medium was prepared in which an adhesion layer, a soft magnetic layer, a first underlayer, a second underlayer, a magnetic layer, and a protective layer were sequentially provided on a substrate having a diameter of 65 mm. The protective layer was formed of carbon.

[0613] On the protective layer of the magnetic recording medium having each layer formed thereon, the lubricating layer forming solutions of Examples 1 to 25 and Comparative Examples 1 to 7 were applied by dipping. The dipping method was performed under the conditions of dipping speed of 10 mm / sec, dipping time of 30 sec, and pulling speed of 1.2 mm / sec.

[0614] Then, the magnetic recording medium coated with the lubricating layer forming solution is added to a constant temperature bath, the solvent in the lubricating layer forming solution is removed, and a heat treatment is performed at 120°C for 10 minutes to improve the adhesion between the protective layer and the lubricating layer, thereby forming a lubricating layer on the protective layer to obtain a magnetic recording medium.

[0615] (Film thickness measurement)

[0616] The film thickness of the lubricating layer of the magnetic recording media of Examples 1 to 25 and Comparative Examples 1 to 7 obtained in this manner was measured using FT-IR (trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific).

[0617] Next, the magnetic recording media of Examples 1 to 25 and Comparative Examples 1 to 7 were subjected to the chemical substance resistance test and pickup characteristic test described below.

[0618] [Chemical resistance test]

[0619] The contamination of magnetic recording media by environmental substances that generate contaminants in a high temperature environment was investigated by the following method: Si ions were used as environmental substances, and the amount of Si adsorption was measured as the amount of contaminants generated by the environmental substances that contaminated the magnetic recording medium.

[0620] Specifically, the magnetic recording medium as the evaluation object was kept for 240 hours in the presence of siloxane-based Si rubber under a high temperature environment of 85°C and 0% humidity. Next, the Si adsorption amount present on the surface of the magnetic recording medium was measured using secondary ion mass spectrometry (SIMS) analysis, and the degree of contamination caused by Si ions was evaluated as the Si adsorption amount. The evaluation of the Si adsorption amount was evaluated based on the following evaluation criteria using the numerical value when the result of Comparative Example 1 was set to 1.00. The results are shown in Tables 3 and 4.

[0621] “Evaluation Benchmarks”

[0622] ◎(Excellent): Si adsorption is less than 0.70 (Si adsorption is very small)

[0623] ○ (good): Si adsorption amount is 0.70 or more and less than 0.90 (Si adsorption amount is small)

[0624] △ (pass): Si adsorption is 0.90 or more and less than 1.10 (Si adsorption is high)

[0625] × (unqualified): Si adsorption amount is 1.10 or more (Si adsorption amount is very high)

[0626] [Pickup characteristics test]

[0627] The magnetic recording medium and the magnetic head are mounted on the spin stand, and the magnetic head is rotated at room temperature under reduced pressure (about 250 Torr) to float the magnetic head at a fixed point for 10 minutes. Then, the surface of the magnetic head opposite to the magnetic recording medium is analyzed using an ESCA (Electron Spectroscopy for Chemical Analysis) analysis device. The intensity (signal intensity (au)) of the peak derived from fluorine obtained by the analysis using the ESCA analysis device represents the amount of lubricant attached to the magnetic head. Using the obtained signal intensity, the pickup characteristics are evaluated by the evaluation criteria shown below. The results are shown in Tables 3 and 4.

[0628] “Evaluation Benchmarks”

[0629] ◎(Excellent): Signal strength below 160 (very little adhesion)

[0630] ○ (good): signal strength 161 to 300 (little adhesion)

[0631] △ (qualified): signal strength 301-1000 (high adhesion)

[0632] × (unqualified): signal strength 1001 or more (very high amount of adhesion)

[0633] Table 3

[0634]

[0635] Table 4

[0636]

[0637] As shown in Table 3, the magnetic recording media of Examples 1 to 25 having a lubricating layer formed using any one of compounds (A) to (X) and (XX) were evaluated as ◎ (excellent) or 0 (good) in the chemical resistance test and the pickup characteristic test. Therefore, it can be confirmed that the lubricating layer of the magnetic recording media of Examples 1 to 25 has good chemical resistance and good pickup suppression effect.

[0638] This is presumably because compounds (A) to (X) and (XX) are all fluorinated ether compounds represented by formula (1). More specifically, this is presumably because compounds (A) to (X) and (XX) are all arranged in the perfluoropolyether chain (R3 ) and the terminal group (R 1 ) between R 2 , configured in R 3 With the terminal group (R 6 ) between R 5 , in the case of 2 to 3 R 3 In the case of configuration in R 3 R between each other 4 None of them contain secondary hydroxyl groups, and they have a side chain portion that branches from the chain structure of the fluorinated ether compound to form an ether bond, the side chain portion has a primary hydroxyl group configured at the front end, and has a connecting group containing a methylene group (-CH2-) that connects the carbon atom bonded to the primary hydroxyl group and the oxygen atom bonded to the carbon atom of the main chain portion.

[0639] On the other hand, as shown in Table 4, all of Comparative Examples 1 to 7 having lubricating layers formed using any of Compounds (Y) to (AE) were evaluated as △ (passed) or × (failed) in the chemical resistance test and the pickup property test.

[0640] This is presumably because in Comparative Examples 1 to 6, the lubricating layer was formed using compounds (Y) to (AD) in which the linking group between the perfluoropolyether chain and the terminal group and / or the linking group between the perfluoropolyether chains contained a secondary hydroxyl group.

[0641] In addition, in Comparative Example 7, a lubricating layer was formed using a compound (AE) that does not contain a secondary hydroxyl group. However, the compound (AE) does not contain a connecting group of a side chain portion that branches from the chain structure of the fluorinated ether compound and performs ether bonding between the perfluoropolyether chain and the terminal group. In more detail, the two hydroxymethyl groups (-CH2OH) respectively arranged at the two ends of the compound (AE) are not ether-bonded to the tertiary carbon that forms the chain structure of the fluorinated ether compound, so the flexibility is insufficient. In addition, for the compound (AE), the two primary hydroxyl groups respectively arranged at the two ends are combined with the tertiary carbon that forms the chain structure of the fluorinated ether compound via one methylene group. Therefore, for the compound (AE), the tertiary carbons respectively arranged at the two ends are close to the two primary hydroxyl groups, and the movement of the two primary hydroxyl groups is easily hindered by the bulky tertiary carbons. Based on these circumstances, it is inferred that in Comparative Example 7 having a lubricating layer formed using compound (AE), the fluidity around the primary hydroxyl groups in compound (AE) becomes insufficient, resulting in insufficient adsorption capacity due to the interaction between the primary hydroxyl groups and the active points on the protective layer, resulting in poor evaluations in the chemical resistance test and the pickup characteristics test.

[0642] In addition, as shown in Table 3, in Examples 1 to 25, Examples 1 to 3 and 7 to 25 having lubricating layers formed using compounds (A) to (C), (G) to (X), and (XX) containing no secondary hydroxyl groups all received a rating of ◎ (excellent) in the chemical resistance test, which is a very good result. Therefore, it can be confirmed that by using a compound containing no secondary hydroxyl groups at all, the lubricating layer can be formed in a manner similar to that of using a compound containing no secondary hydroxyl groups in R 1 and R 6 Compared with the case of using a compound containing a secondary hydroxyl group, a lubricating layer having better chemical resistance can be obtained.

[0643] As shown in Table 3, the evaluation of the pickup characteristic test was ◎ (excellent) in both Examples 1 and 3, which was a very good result. On the other hand, in Example 2, the evaluation of the pickup characteristic test was ○ (good).

[0644] This is because, in Examples 1 and 3, the 1 (=R 6 ) contains hydroxyl groups and R 2 (=R 5 ) wherein the number of carbon atoms between the tertiary carbons contained in the compounds (A) and (C) is 2 or more, whereas in Example 2, 1 (=R 6 ) contains hydroxyl groups and R 2 (=R 5 ) is a compound (B) in which the number of carbon atoms between the tertiary carbons contained in the compound (A) and (C) is 1. Due to this difference, R 1 (=R 6 ) contains hydroxyl groups and R 2 (=R 5 ) is considered to be more appropriate. As a result, it is estimated that compounds (A) and (C) have a greater R 1 (=R 6 ) contains primary hydroxyl groups that are not easily affected by R 2 (=R 5 ) has a primary hydroxyl group, and R 2 (=R 5 ) is hindered by the bulky tertiary carbon contained in it.

[0645] As shown in Table 3, the evaluation of the pickup characteristics test was ◎ (excellent) in both Examples 4 and 5, which was a very good result. On the other hand, in Example 6, the evaluation of the pickup characteristics test was ○ (good).

[0646] This is because, in Examples 4 and 5, R 1 and R 6In contrast to the compounds (D) and (E) which do not contain a rigid structure, in Example 6, R 1 and R 6 Compound (F) contains a relatively rigid phenyl group. The reason is presumed to be that, due to this difference, R 1 (=R 6 ) is not easily hindered in its movement of hydroxyl groups, R 1 and R 6 The hydroxyl groups in the molecule can move freely.

[0647] Industrial Availability

[0648] The present invention provides a fluorine-containing ether compound which can form a lubricating layer having excellent chemical resistance and capable of suppressing pickup.

[0649] By using the lubricant for a magnetic recording medium containing the fluorinated ether compound of the present invention, it is possible to form a lubricating layer which has excellent chemical resistance and a good pickup suppression effect even if the thickness is thin.

[0650] Explanation of symbols

[0651] 10···magnetic recording medium, 11···substrate, 12···adhesion layer, 13···soft magnetic layer, 14···first base layer, 15···second base layer, 16···magnetic layer, 17···protective layer, 18···lubricating layer.

Claims

1. A fluorine-containing ether compound, characterized in that It is represented by the following formula (1): R 1 -R 2 -CH2-R 3 [-CH2-R 4 -CH2-R 3 ] x -CH2-R 5 -R 6 (1) In formula (1), R 1 and R 6 Each independently represents an organic group having 1 to 50 carbon atoms; R 2 is a divalent linking group represented by the following formula (2-1) or (2-2); R 5 is a divalent linking group represented by the following formula (2-3) or (2-4); x represents an integer of 0 to 2; R 3 is a perfluoropolyether chain; when x is 1 or 2, 2 or 3 R 3 They may be partly or completely the same, or they may be different; R 4 is a divalent linking group represented by the following formula (3-1) or formula (3-2); when x is 2, two R 4 They can be the same or different; In formula (2-1), n1 represents an integer of 2 to 4; in formula (2-1), the dotted line bonded to the carbon atom represents the bond with R 1 The dotted line that is bonded to the oxygen atom represents the bond that is bonded to the methylene group; In formula (2-2), the dotted line connected to the carbon atom represents the 1 The dotted line that is bonded to the oxygen atom represents the bond that is bonded to the methylene group; In formula (2-3), n2 represents an integer of 2 to 4; in formula (2-3), the dotted line bonded to the carbon atom represents the bond with R 6 The dotted line that is bonded to the oxygen atom represents the bond that is bonded to the methylene group; In formula (2-4), the dotted line connected to the carbon atom represents the 6 The dotted line that is bonded to the oxygen atom represents the bond that is bonded to the methylene group; In formula (3-1), n3 represents an integer of 2 to 4; y1 represents an integer of 1 to 3; y2 represents an integer of 1 to 3; at least one of y1 and y2 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 6 The side methylene bond is bonded to the bond; In formula (3-2), y3 represents an integer of 1 to 3; y4 represents an integer of 1 to 3; at least one of y3 and y4 is 1; the dotted line bonded to the oxygen atom on the left represents the bond with R 1 The dotted line on the right side represents the bond to the methylene group on the side, and the dotted line on the right side represents the bond to the oxygen atom on the R 6 The side methylene bond is bonded to the bond.

2. The fluorinated ether compound according to claim 1, wherein R in the formula (1) 2 is the formula (2-1), R 5 For the formula (2-3), x R 4 All of them are the formula (3-1), in which y1 is 1 and y2 is 1. 3 . The fluorine-containing ether compound according to claim 2 , wherein n1 in the formula (2-1), n2 in the formula (2-3), and n3 in the formula (3-1) are all the same value.

4. The fluorinated ether compound according to claim 1, wherein R in the formula (1) 2 is the formula (2-2), R 5 For the formula (2-4), x R 4 All of them are the formula (3-2), in which y3 is 1 and y4 is 1.

5. The fluorinated ether compound according to claim 1, wherein R in the formula (1) 1 and R 6 are each independently any one of an organic group having a polar group, an organic group having a carbon-carbon unsaturated bond, and an organic group having both a polar group and a carbon-carbon unsaturated bond, The polar group is at least one selected from a hydroxyl group, an amino group, a carboxyl group, a formyl group, a carbonyl group, a sulfonyl group, a cyano group, and a group having an amide bond, The carbon-carbon unsaturated bond is at least one selected from an aromatic hydrocarbon group, an unsaturated heterocyclic group, an alkenyl group, and an alkynyl group which may have a substituent.

6. The fluorinated ether compound according to claim 1 or 5, wherein R in the formula (1) 1 and R 6 The total number of polar groups contained is 1-4.

7. The fluorinated ether compound according to claim 1 or 5, wherein R in the formula (1)1 -R 2 -With R 6 -R 5 -same.

8. The fluorinated ether compound according to claim 1 or 5, wherein the (x+1) R in the formula (1) 3 Each is independently a perfluoropolyether chain represented by the following formula (4); -(CF2) w1 -O-(CF2O) w2 -(CF2CF2O) w3 -(CF2CF2CF2O) w4 -(CF2CF2CF2CF2O) w5 -(CF2) w6 -(4) In formula (4), w2, w3, w4, and w5 represent average polymerization degrees, and each independently represents 0 to 20; wherein, w2, w3, w4, and w5 are not all 0 at the same time; w1 and w6 are average values ​​of the number of CF2, and each independently represents 1 to 3; there is no particular restriction on the arrangement order of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O) as repeating units in formula (4).

9. The fluorinated ether compound according to claim 1 or 5, wherein the (x+1) R in the formula (1) 3 Each independently represents any one of the perfluoropolyether chains selected from the group consisting of the following formulae (4-1) to (4-4); -CF2-(OCF2CF2) h -(OCF2) i -OCF2-(4-1) In formula (4-1), h and i represent the average degree of polymerization, h represents 1 to 20, and i represents 0 to 20; -CF2CF2-(OCF2CF2CF2) j -OCF2CF2-(4-2) In formula (4-2), j represents the average degree of polymerization and is 1 to 15; -CF2CF2CF2-(OCF2CF2CF2CF2) k -OCF2CF2CF2-(4-3) In formula (4-3), k represents the average degree of polymerization and is 1 to 10; -(CF2) w7 -O-(CF2CF2CF2O) w8 -(CF2CF2O) w9 -(CF2) w10 -(4-4) In formula (4-4), w8 and w9 represent average polymerization degrees, and each independently represents 1 to 20; w7 and w10 represent average values ​​of the number of CF2, and each independently represents 1 to 2.

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

11. A lubricant for a magnetic recording medium, characterized in that: Contains the fluorine-containing ether compound according to claim 1 or 5.

12. A magnetic recording medium, characterized in that: A magnetic recording medium having at least a magnetic layer, a protective layer, and a lubricating layer arranged in sequence on a substrate. The lubricating layer comprises the fluorine-containing ether compound according to claim 1 or 5. 13 . The magnetic recording medium according to claim 12 , wherein the lubricating layer has an average film thickness of 0.5 nm to 2.0 nm.

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