Fluoropolyether compounds, lubricants, magnetic disks, and methods for producing fluoropolyether compounds

Abstract

To provide a lubricant for use in energy-assisted magnetic disk devices like HAMR, capable of inhibiting oxidative degradation in an oxygen-containing atmosphere and sustaining high heat resistance.SOLUTION: A fluoropolyether compound includes at least one ether linkage in its molecule. In the molecular structure, at least one hydrogen atom bonded to the carbon atom linked to the oxygen atom of an ether linkage has undergone fluorine substitution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to fluoropolyether compounds, lubricants, magnetic disks, and methods for producing fluoropolyether compounds. [Background technology]

[0002] To increase the storage capacity of magnetic disk drives such as hard disk drives (HDDs), development of energy-assisted magnetic disk drives, such as heat-assisted magnetic recording (HAMR), is underway.

[0003] In energy-assisted magnetic disk drives, energy is applied to the magnetic layer using a laser or microwave during data recording to control the magnetism of the magnetic disk, and this energy heats the magnetic layer.

[0004] Surface lubricants for magnetic disks are applied to the outermost surface of the magnetic disk for surface protection. In energy-assisted magnetic disk drives, the surface lubricant for the magnetic disk is also exposed to high temperatures. Therefore, there is a need for a highly heat-resistant lubricant that can maintain its surface protection layer even at high temperatures.

[0005] Lubricants for magnetic disks used in energy-assisted magnetic disk drives such as HAMR are known to be those in which a hydrocarbon group containing a hydroxyl group is introduced at the terminal end of a perfluoropolyether group (see, for example, Patent Documents 1-3), and these lubricants have high affinity for disks and high heat resistance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2009 / 066784 [Patent Document 2] International Publication No. 2021 / 002178 [Patent Document 3] International Publication No. 2016 / 084781 [Overview of the project] [Problems that the invention aims to solve]

[0007] In energy-assisted systems such as HAMR, the magnetic disk is exposed to high temperatures, but conventional lubricants had room for improvement in terms of heat resistance to withstand the heating caused by HAMR.

[0008] Normally, magnetic disks are written to in an inert gas such as helium. Even in inert gases, trace amounts of oxygen may be present. The inventors have independently discovered that in such cases, oxidative decomposition of the lubricant occurs, leading to the disappearance of the lubricant or a change in its structure, resulting in a decrease in lubrication performance. Therefore, the inventors set forth the objective of providing a lubricant that can suppress decomposition even when the disk is heated in energy-assisted magnetic disk drives such as HAMR.

[0009] In other words, one aspect of the present invention aims to provide a fluoropolyether compound, a lubricant, and a magnetic disk that can suppress decomposition in an oxygen-containing atmosphere and maintain high heat resistance, as well as a method for producing the fluoropolyether compound. [Means for solving the problem]

[0010] To solve the aforementioned problems, the present invention includes the following embodiments.

[0011] [1] A fluoropolyether compound represented by the following formula (1). [ka] (In formula (1), each Rf is independently a perfluoropolyether group, R 1 This refers to a hydrocarbon group having two or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. R 2and R 3 is, independently of one another, a hydrocarbon group having one or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups, L 1 L 2 L 3 and L 4 are, independently of one another, hydrocarbon groups, and each of the hydrocarbon groups may independently contain an OH group and / or an ether bond, R 4 is a hydrogen atom or a hydrocarbon group, and the hydrocarbon group may contain an OH group and / or an ether bond, p is an integer of 0 to 1, q is a real number of 0 to 10, when p = 1, x = 1 and y = 1, or x = 2 and y = 0, In the molecule, a hydrogen atom bonded to a carbon atom contained in the hydrocarbon group may be substituted with a fluorine atom, R 1 R 2 and R 3 at least any one of them may contain an ether bond in which at least one carbon atom is substituted with an oxygen atom, and at least one hydrogen atom bonded to a carbon atom adjacent to the oxygen atom of the ether bond is substituted with a fluorine atom) [2] R 1 is a hydrocarbon group having 2 to 10 carbon atoms and having two or more OH groups, or a hydrocarbon group having 3 to 25 carbon atoms and having one or more cyclic hydrocarbon groups, R 2 and R 3 are, independently of one another, a hydrocarbon group having 1 to 10 carbon atoms and having one or more OH groups, or a hydrocarbon group having 3 to 25 carbon atoms and having one or more cyclic hydrocarbon groups, R 1 R 2 and R 3 at least any one of them may contain an ether bond in which at least one carbon atom is substituted with an oxygen atom, the fluoropolyether compound according to [1].

[0012] [3] L 1 L 2 L3 , and L 4 The fluoropolyether compound according to [1] or [2], wherein is a hydrocarbon group having 1 to 25 carbon atoms, and each hydrocarbon group independently has one or more OH groups and / or may contain an ether bond.

[0013] [4] R 1 , R 2 and R 3 The fluoropolyether compound according to any one of [1] to [3], wherein if at least one of the contains an ether bond, all hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of at least one such ether bond are substituted with fluorine atoms.

[0014] [5] R 1 , R 2 and R 3 The fluoropolyether compound according to any one of [1] to [4], wherein if at least one of the contains an ether bond, all hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of all such ether bonds are substituted with fluorine atoms.

[0015] [6] L 1 , L 2 , L 3 , L 4 , and R 4 The fluoropolyether compound according to any one of [1] to [5], wherein if at least one of the contains an ether bond, all hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of all such ether bonds are substituted with fluorine atoms.

[0016] [7] R 1 , R 2 , R 3 , R 4 , L 1 , L 2 , L 3 , and L 4A fluoropolyether compound according to any one of [1] to [6], wherein all hydrogen atoms bonded to carbon atoms other than the carbon atom bonded to the OH group are substituted with fluorine atoms.

[0017] A lubricant comprising any of the fluoropolyether compounds described in [8], [1], to [7].

[0018] [9] A magnetic disk in which a recording layer, a protective layer and a lubricating layer are stacked in this order, wherein the lubricating layer contains the lubricant described in [8].

[0019]

[10] An esterification step in which an ester is introduced into the compound represented by the following formula (2), A method for producing a fluoropolyether compound, comprising: a fluorination step of fluorinating the ester obtained in the esterification step; and a reduction step of reducing the fluorinated ester obtained in the fluorination step. [ka] (In formula (2), Rf' is independently a perfluoropolyether group, R 11 , R 12 and R 13 Each of these is an independent hydrocarbon group having one or more OH groups. L 11 , L 12 , L 13 , and L 14 Each of these is independently a hydrocarbon group, and each of these hydrocarbon groups may independently contain an OH group and / or an ether bond. R 14 is a hydrocarbon group or a hydrogen atom, and the hydrocarbon group may have an OH group and / or may contain an ether bond. R 11 , R 12 and R 13 At least one of them includes an ether bond in which at least one carbon atom is substituted by an oxygen atom, p is an integer between 0 and 1, and q is a real number between 0 and 10. When p=1, x=1 and y=1, or x=2 and y=0. [Effects of the Invention]

[0020] According to one aspect of the present invention, it is possible to provide a fluoropolyether compound that can suppress decomposition in an oxygen-containing atmosphere and maintain high heat resistance, a lubricant, and a magnetic disk having a lubricating layer containing the lubricant formed on it. [Brief explanation of the drawing]

[0021] [Figure 1] This is a cross-sectional view showing the configuration of a magnetic disk in one device. [Figure 2] This is a cross-sectional view showing the configuration of a magnetic disk in one device. [Modes for carrying out the invention]

[0022] Embodiments of the present invention will be described in detail below. However, the present invention is not limited thereto, and various modifications are possible within the scope described. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the present invention. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or greater, B or less".

[0023] [1. Fluoropolyether compounds] In view of the above-mentioned problems, the present inventors conducted diligent studies and considered that lubricants, such as those described in Patent Documents 1-3, in which a hydrocarbon group containing a hydroxyl group is introduced at the end of a perfluoropolyether group, are prone to oxidative decomposition of the ether portion in a high-temperature, oxygen-containing atmosphere. Therefore, they synthesized a fluoropolyether compound in which the hydrogen atom bonded to the carbon atom bonded to the oxygen atom of the ether bond in the molecule was substituted with fluorine, and evaluated its oxidation stability. They found that decomposition was less likely to occur even in a high-temperature, oxygen-containing atmosphere, thus completing the present invention. Furthermore, it was found that in a magnetic disk in which a lubricating layer was formed using such a fluoropolyether compound as a lubricant, the retention rate of the lubricating layer was high even after heat treatment in a high-temperature, oxygen-containing atmosphere. In addition, it was shown that in a magnetic disk in which a lubricating layer was formed using the fluoropolyether compound as a lubricant, the retention rate of the lubricating layer was also high after irradiation with ultraviolet light.

[0024] In other words, the fluoropolyether compound according to one embodiment of the present invention is a fluoropolyether compound represented by the following formula (1). [ka] (Rf in equation (1)) In formula (1), each Rf is independently a perfluoropolyether group. The perfluoropolyether group is not particularly limited, but for example, the perfluoropolyether group represented by the following formula (4) can be mentioned. -(CF2) g -O-(CF2O) b (CF2CF2O) c (CF2CF2CF2O) d (CF2CF2CF2CF2O) e (CF2CF(CF3)O) f -(CF2) h - ...(4) In equation (4), b, c, d, e, and f are independent real numbers between 0 and 30 in each Rf, more preferably between 0 and 25. However, at least one of b, c, d, e, and f is a real number of 1 or greater. Also, g and h are independent integers between 0 and 3 in each Rf. Here, the values ​​of b, c, d, e, and f were obtained using JEOL JNM-ECX400. 19 These values ​​were calculated by 1F-NMR measurement. In the NMR measurement, the sample itself was measured without using a solvent. The chemical shift reference was substituted with a known peak representing part of the fluoropolyether's skeletal structure.

[0025] For example, Rf can be represented by the Demnam skeleton (C3 skeleton): -(CF2CF2CF2O) d - Fomblin skeleton (C1C2 skeleton): -(CF2O) b (CF2CF2O) c -, C2 skeleton:-(CF2CF2O) c - C4 skeleton:-(CF2CF2CF2CF2O) e -, and the Krytox skeleton:-(CF2CF(CF3)O) f -Examples include perfluoropolyether groups comprising at least one selected from the above.

[0026] A more preferred example of the Rf is a group in formula (4) in which b, c, d, e, and f are any of the following (i) to (v). The following configuration is preferred because it results in a flatter molecular chain.

[0027] (i) b = a real number between 2 and 12, and c = a real number between 2 and 12, and d ~ f = 0 (ii) c = a real number between 4 and 14, and b and d ~ f = 0 (iii) d = a real number between 2 and 12, and b, c, e and f = 0 (iv) e = a real number between 1 and 9, and b to d and f = 0 (v) f = a real number between 2 and 12, and b ~ e = 0 Furthermore, in the fomblin skeleton, CF2O and CF2CF2O can be repeated randomly.

[0028] (R in equation (1)) 1 ) In formula (1), R 1 This refers to a hydrocarbon group having two or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. 1 Having two or more OH groups or one or more cyclic hydrocarbon groups is preferable because it improves the adhesion between the fluoropolyether compound represented by formula (1) and the magnetic disk.

[0029] The hydrocarbon group having two or more OH groups is not limited to this, but is a hydrocarbon group having two or more OH groups and having 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, and even more preferably 2 to 3 carbon atoms. The hydrocarbon group may be linear or branched. The number of OH groups in the hydrocarbon group having two or more OH groups is not limited to two or more, but is for example 2 to 8, more preferably 2 to 6, and even more preferably 2 to 4. From the viewpoint of adhesion to magnetic disks, it is preferable to include primary OH groups. The hydrocarbon group having two or more OH groups may include ether bonds in which carbon atoms of the hydrocarbon group are substituted with oxygen atoms. If ether bonds are included, the number of ether bonds is for example 0 to 10, more preferably 0 to 5, and even more preferably 0 to 3. A more preferred example of the hydrocarbon group having two or more OH groups is, for example, the group represented by the following formula (5) or (6). -(CH2)rO-(CH2)s-CH(OH)-CH2(OH) ···(5) -(CH2)tO-(CH2)u-CH((CH2)v-OH)((CH2)w -OH) ···(6) In equation (5), r is an integer between 0 and 3, and s is an integer between 0 and 3. In equation (6), t is an integer between 0 and 3, u is an integer between 0 and 4, v is an integer between 1 and 5, and w is an integer between 1 and 5. More preferred examples of the group represented by equation (5) or (6) include -CH2OCH2CH(OH)CH2OH and -CH2OCH2CH2CH(CH2-OH)2.

[0030] Other examples of hydrocarbon groups having two or more OH groups include -CH2OCH2CH(OH)CH2OCH2CH(OH)CH2OH, -CH2OCH2CH(OH)CH2OCH2C(CH2CH3)(CH2OH)2, and -CH2OCH2CH(OH)CH2OCH2CH2OH.

[0031] The hydrocarbon group having one or more cyclic hydrocarbon groups is not limited to the above, but is a hydrocarbon group having one or more cyclic hydrocarbon groups and having 3 to 25 carbon atoms, more preferably 3 to 18 carbon atoms, and even more preferably 7 to 12 carbon atoms. The hydrocarbon group may contain ether bonds in which the carbon atoms of the hydrocarbon group are substituted with oxygen atoms. As long as the hydrocarbon group has one or more cyclic hydrocarbon groups, the portion other than the cyclic hydrocarbon group may be linear or branched.

[0032] The hydrocarbon group having one or more cyclic hydrocarbon groups is not limited to having one or more cyclic hydrocarbon groups, but for example, it may have 1 to 5 groups, more preferably 1 to 3 groups, and even more preferably 1 to 2 groups. The cyclic hydrocarbon group may be, for example, a cyclic hydrocarbon group having 3 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 5 to 6 carbon atoms, and may be monosubstituted, disubstituted, or polysubstituted. The cyclic hydrocarbon group may also be an alicyclic hydrocarbon group, an aromatic hydrocarbon group, a monocyclic hydrocarbon group, or a condensed polycyclic hydrocarbon group. Examples of the cyclic hydrocarbon group include a phenyl group, a phenylene group, a naphthyl group, a naphthylene group, a cyclohexyl group, a cyclohexylene group, a cyclopentyl group, a cyclopentylene group, and the like.

[0033] The number of ether bonds in the hydrocarbon group having one or more cyclic hydrocarbon groups is not limited to this, but is, for example, 0 to 10, more preferably 0 to 5, and even more preferably 0 to 3.

[0034] R 1 If the hydrocarbon group has one or more cyclic hydrocarbon groups, it is more preferable that the hydrocarbon group has one or more OH groups. That is, the hydrocarbon group having one or more cyclic hydrocarbon groups as described above is more preferably a hydrocarbon group having one or more OH groups and one or more cyclic hydrocarbon groups. 1 Having one or more OH groups and one or more cyclic hydrocarbon groups is preferable because it improves the adhesion between the fluoropolyether compound represented by formula (1) and the magnetic disk, even if the cyclic hydrocarbon group is an alicyclic hydrocarbon group.

[0035] The number of OH groups in the hydrocarbon group having one or more OH groups and one or more cyclic hydrocarbon groups is not limited as long as there is one or more, but for example it is 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3.

[0036] Examples of hydrocarbon groups having one or more cyclic hydrocarbon groups include the group represented by the following formula (7). -(CH2)iO-(CH2)j-CH(OH)-(CH2)kOAR 5 ...(7) In formula (7), i is an integer from 1 to 3, j is an integer from 1 to 3, k is an integer from 1 to 3, m is an integer from 1 to 10, A is the cyclic hydrocarbon group, and R 5 These include -H, -OH, -NO2, perfluoroalkyl groups having 1 to 10 carbon atoms (e.g., -CF3), and alkoxy groups having 1 to 10 carbon atoms (e.g., methoxy group, ethoxy group, propoxy group). Preferred examples include -CH2OCH2CH(OH)CH2OC6H5 and -CH2OCH2CH(OH)CH2OC 10 H7, -CH2OCH2CH(OH)CH2O(C6H4)NO 2、 and -CH2OCH2CH(OH)CH2O(C6H5)OH, -CH2OCH2CH(OH)CH2O(C6H 10 )OCH3 can be mentioned.

[0037] (R in equation (1)) 2 and R 3 ) In formula (1), R 2 and R 3 Each of these is independently a hydrocarbon group having one or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. 2 and R 3 Having one or more OH groups or one or more cyclic hydrocarbon groups is preferable because it improves the adhesion between the fluoropolyether compound represented by formula (1) and the magnetic disk.

[0038] The hydrocarbon group having one or more OH groups is, but not limited to, a hydrocarbon group having one or more OH groups, with 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms. The hydrocarbon group may be linear or branched. The number of the one or more OH groups in the hydrocarbon group having one or more OH groups is not limited as long as it has one or more OH groups, but is, for example, 1 to 8, more preferably 2 to 6, and even more preferably 2 to 4. From the viewpoint of adhesion to the magnetic disk, it is preferable to contain a primary OH group. The hydrocarbon group may contain an ether bond in which a carbon atom of the hydrocarbon group is substituted by an oxygen atom. The number of ether bonds contained in the hydrocarbon group having one OH group is also not limited to this, but is, for example, 0 to 10, more preferably 0 to 5, and even more preferably 0 to 3. When the hydrocarbon group having one OH group has one OH group, a more preferable example is, for example, a group represented by the following formula (8). -(CH2)n-OH ···(8) In formula (8), n is an integer of 0 to 3. When the hydrocarbon group having one OH group has two or more OH groups, a more preferable example is the same as the hydrocarbon group having two or more OH groups described for R 1 .

[0039] The hydrocarbon group having one or more cyclic hydrocarbon groups is the same as the group described for R 1 .

[0040] (L 1 , L 2 , L 3 , and L 4 in formula (1)) In formula (1), L 1 , L 2 , L 3 , and L 4 are each independently a hydrocarbon group that may contain an OH group and / or an ether bond. L 1 , L 2 , L 3 , and L4 Preferably, each independently has one or more OH groups. L 1 L 2 L 3 and L 4 having one or more OH groups is preferable because the adhesion between the fluoropolyether compound represented by the formula (1) and the magnetic disk is improved. The hydrocarbon group that may contain an ether bond is a hydrocarbon group containing an ether bond in which a carbon atom of the hydrocarbon group is substituted by an oxygen atom.

[0041] The hydrocarbon group is, but not limited to, a hydrocarbon group having 1 to 25 carbon atoms, more preferably 2 to 18 carbon atoms, and even more preferably 2 to 12 carbon atoms. The carbon atom of the hydrocarbon group may be substituted by an oxygen atom to form an ether bond. The hydrocarbon group may be linear or branched. When the hydrocarbon group has one or more OH groups, the number of OH groups is, for example, 1 to 8, more preferably 1 to 5, and even more preferably 1 to 3. When the hydrocarbon group contains an ether bond, the number of ether bonds is, for example, 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3.

[0042] (R in formula (1) 4 ) In formula (1), R 4 is a hydrocarbon group or a hydrogen atom. The hydrocarbon group is preferably a hydrocarbon group having 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 5 carbon atoms. The hydrocarbon group may contain an ether bond in which a carbon atom of the hydrocarbon group is substituted by an oxygen atom. The hydrocarbon group may be linear or branched. The hydrocarbon group may have an OH group, and the number of OH groups is, for example, 0 to 8, more preferably 0 to 5, and even more preferably 0 to 2. The number of ether bonds contained in the hydrocarbon group is, for example, 0 to 8, more preferably 0 to 5, and even more preferably 0 to 3.

[0043] (p, q, x, y in equation (1)) In equation (1), p is an integer between 0 and 1, and q is a real number between 0 and 10. When p=1, x=1 and y=1, or x=2 and y=0. q was determined using the method described above with a JEOL JNM-ECX400. 1 This is an average value calculated by 1H-NMR measurement, and is a real number.

[0044] (Fluorine substitution) The fluoropolyether compound represented by formula (1) is R 1 , R 2 and R 3 At least one of them may include an ether bond in which at least one carbon atom is substituted by an oxygen atom, in which case R 1 , R 2 and R 3 In this compound, at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bond is replaced by a fluorine atom. Here, "carbon atom adjacent to the oxygen atom of the ether bond" refers to the carbon atom bonded to the oxygen atom of the ether bond. When a fluoropolyether compound with this configuration is used as a lubricant, it has been found that decomposition of the lubricant is less likely to occur even in a high-temperature, oxygen-containing atmosphere. This is thought to be because, as at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bond in the molecule is replaced by a fluorine atom, oxidative decomposition of the ether moiety in a high-temperature, oxygen-containing atmosphere is less likely to occur.

[0045] The fluoropolyether compound represented by formula (1) is the aforementioned R 1 , R 2 and R 3It is sufficient if at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bond is replaced by a fluorine atom, but it is more preferable that at least one hydrogen atom bonded to the carbon atom adjacent to the ether bond in a hydrocarbon group having two or more OH groups, or a hydrocarbon group having a cyclic hydrocarbon group, is replaced by a fluorine atom. This configuration is preferable because it makes it less likely for the lubricant to decompose in a high-temperature, oxygen-containing atmosphere, and maintains a strong bond between the lubricant and the magnetic disk. Furthermore, since there is no part of the ether portion that is prone to oxidative decomposition, R 1 , R 2 and R 3 It is more preferable that all hydrogen atoms bonded to the carbon atom adjacent to the oxygen atom of at least one ether bond are replaced with fluorine atoms. Even more preferable, 1 , R 2 and R 3 In this structure, all hydrogen atoms bonded to carbon atoms adjacent to oxygen atoms in all ether bonds are replaced by fluorine atoms. When a fluoropolyether compound having such a structure is used as a lubricant, decomposition of the lubricant is less likely to occur, even at high temperatures and in an oxygen-containing atmosphere.

[0046] The fluoropolyether compound represented by formula (1) is the aforementioned R 1 , R 2 and R 3 In the ether bond, at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom is substituted with a fluorine atom, but any other hydrogen atoms in the molecule may be substituted with fluorine atoms.

[0047] In particular, the fluoropolyether compound represented by formula (1) is further R 4 , L 1 , L 2 , L 3 , and L 4If at least one of the components includes an ether bond, it is preferable that at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bond is replaced by a fluorine atom. It is even more preferable that all hydrogen atoms bonded to the carbon atoms adjacent to the oxygen atom of the ether bond are replaced by fluorine atoms. Perfluoropolyether compounds with this configuration are less susceptible to oxidative decomposition in the presence of oxygen.

[0048] Furthermore, the fluoropolyether compound represented by formula (1) is R 1 , R 2 , R 3 , R 4 , L 1 , L 2 , L 3 , and L 4 It is even more preferable that all hydrogen atoms bonded to carbon atoms other than the carbon atom bonded to the OH group are replaced with fluorine atoms, as this makes the compound less susceptible to oxidative decomposition in the presence of oxygen.

[0049] (Fluoropolyether compound according to one embodiment of the present invention) The fluoropolyether compound according to one embodiment of the present invention is not particularly limited as long as it is a fluoropolyether compound represented by formula (1), but for example, it may be a fluoropolyether compound represented by the following formulas (1-1), (1-2), (1-3), or (1-4). In the following formulas (1-1) to (1-4), Rf, R 1 , R 2 , R 3 , R 4 , L 1 , L 2 , L 3 , and L 4 Furthermore, fluorine substitution is as described above. [ka] [ka] [ka] [ka] A more specific example of a fluoropolyether compound according to one embodiment of the present invention is, for example, compounds 1 to 6 represented by the following formula. [ka] Compound 1 has p=0 and q=0 in formula (1) above (corresponding to formula (1-1) above). The number of repeating units c' of the perfluoropolyether in compound 1 is the number of repeating units of the perfluoropolyether used in the synthesis of compound 1 (the same applies to compounds 2 to 5 below). In compound 1, the c in the part corresponding to Rf in formula (1) is 2 greater than c' due to substitution by a fluorine atom. [ka] Compound 2 has p=0 and q=0 in formula (1) above (corresponding to formula (1-1) above). [ka] Compound 3 has p=0 and q=1 in formula (1) above (corresponding to formula (1-2) above). [ka] Compound 4 has p=1, q=0, x=1, and y=1 in formula (1) above (corresponding to formula (1-3) above). [ka] Compound 5 has p=1, q=0, x=2, and y=0 in formula (1) above (corresponding to formula (1-4) above). [ka] Compound 6 has p=0 and q=1 in formula (1) above (corresponding to formula (1-2) above). The number of repeating units of the perfluoropolyether in compound 6, d', is the number of repeating units of the perfluoropolyether used in the synthesis of compound 6.

[0050] The fluoropolyether compound according to one embodiment of the present invention is preferably liquid or solid under normal conditions, and its number average molecular weight is preferably 600 to 10,000. From the viewpoint of the evaporability of the lubricant, it is more preferable that the number average molecular weight is 1,000 or more. The fluoropolyether compound according to one embodiment of the present invention is suitably used as a lubricant. The number average molecular weight was determined using the aforementioned JEOL JNM-ECX400. 1 H and 19 This value was calculated by F-NMR measurement.

[0051] [2. Method for producing fluoropolyether compounds] The method for producing a fluoropolyether compound according to one embodiment of the present invention is not particularly limited as long as it is a method capable of producing a fluoropolyether compound according to one embodiment of the present invention. The fluoropolyether compound according to one embodiment of the present invention can be produced by fluorinating a perfluoropolyether derivative ester or a polyalkylene glycol derivative ester.

[0052] [2.1 Method for fluorinating perfluoropolyether derivative esters] The following describes a method for producing a fluoropolyether compound by fluorinating a perfluoropolyether derivative ester. The method for producing a fluoropolyether compound according to this embodiment includes, for example, an esterification step of introducing an ester into a compound represented by the following formula (2) (hereinafter sometimes referred to as "perfluoropolyether derivative"), a fluorination step of fluorinating the ester obtained in the esterification step (hereinafter sometimes referred to as "perfluoropolyether derivative ester"), and a reduction step of reducing the fluorinated ester obtained in the fluorination step (hereinafter sometimes referred to as "fluorinated perfluoropolyether derivative ester"). [ka] In formula (2), Rf' is independently a perfluoropolyether group, and R 11 , R 12 and R 13 Each of these is independently a hydrocarbon group having one or more OH groups or one or more cyclic hydrocarbon groups, L 11 , L 12 , L 13 , and L 14 Each of these is independently a hydrocarbon group, and R 14 x is a hydrocarbon group or a hydrogen atom, p is an integer between 0 and 1, q is a real number between 0 and 10, and when p=1, x=1 and y=1, or x=2 and y=0.

[0053] R 11 , R 12 and R 13 At least one of them contains an ether bond in which at least one carbon atom is substituted by an oxygen atom. 11 , L 12 , L 13 , and L 14 Each of these may independently have an OH group and / or contain an ether bond. 14 If is a hydrocarbon group, the hydrocarbon group may have one or more OH groups and / or may contain an ether bond.

[0054] Typically, methods for producing fluoropolyether compounds by fluorination have involved fluorinating hydrocarbon compounds such as polyalkylene glycols. However, when producing fluoropolyether compounds with high molecular weights, fluorination of such compounds was difficult (see Japanese Patent Publication No. 2018-90492). The present inventors have discovered a method for fluorinating fluoropolyether compounds with high molecular weights.

[0055] In formula (2), each Rf' is independently a perfluoropolyether group. Examples of the perfluoropolyether group include the perfluoropolyether group shown in formula (4') below. -(CF2) g’ -O-(CF2O) b’ CF2CF2O) c’ (CF2CF2CF2O) d’ (CF2CF2CF2CF2O) e’ (CF2CF(CF3)O) f’ -(CF2) h’ - ...(4') In equation (4'), b', c', d', e', and f' are independent real numbers between 0 and 30 in each Rf', more preferably between 0 and 25. However, at least one of b', c', d', e', and f' is a real number of 1 or more. Also, g' and h' are independent integers between 0 and 3 in each Rf'. Here, the values ​​of b', c', d', e', and f' are calculated in the same way as the values ​​of b, c, d, e, and f in equation (4) above.

[0056] For example, Rf' is the demnam skeleton (C3 skeleton):-(CF2CF2CF2O) d’ - Fomblin skeleton (C1C2 skeleton): -(CF2O) b’ (CF2CF2O) c’ -, C2 skeleton:-(CF2CF2O) c’ - C4 skeleton:-(CF2CF2CF2CF2O)e’ -, and the Krytox skeleton:-(CF2CF(CF3)O) f’ -Examples include perfluoropolyether groups comprising at least one selected from the above.

[0057] A more preferred example of Rf' is a group similar to any of the groups (i) to (v) exemplified in Rf of formula (1) above. Here, if the portion corresponding to Rf in formula (1) includes a fluoroether group and / or a perfluoroalkyl group produced by fluorine substitution in the fluorination step, then Rf of formula (1) and Rf' may not be the same.

[0058] R in equation (2) 11 , R 12 and R 13 Each of these is not particularly limited as long as it is a hydrocarbon group having one or more OH groups or one or more cyclic hydrocarbon groups independently. The hydrocarbon group having one or more OH groups may be a hydrocarbon group having one OH group or a hydrocarbon group having two or more OH groups. Furthermore, the hydrocarbon group may include one or more OH groups and one or more cyclic hydrocarbon groups.

[0059] R in equation (2) 11 This is R in equation (1) mentioned above. 1 It can be the same as R in equation (2). 12 and R 13 This is R in equation (1) mentioned above. 2 and R 3 It could be the same as this.

[0060] L in equation (2) 11 , L 12 , L 13 , and L 14 This is L in the aforementioned equation (1). 1 , L 2 , L 3 , and L 4 It can be the same as R 14 This is R in equation (1) mentioned above. 4It can be the same as and the p, q, x, and y in equation (2) are the same as the p, q, x, and y in equation (1).

[0061] <Method for producing perfluoropolyether derivatives> (Manufacturing method (1)) The method for producing the perfluoropolyether derivative is not particularly limited, but the perfluoropolyether derivative R in formula (2) is one in which p and q are 0. 11 -Rf-R 12 For example, this can be produced by reacting a perfluoropolyether (A) having OH groups at both ends of the molecule with an epoxide derivative having OH groups and / or cyclic hydrocarbon groups.

[0062] The perfluoropolyether (A) having OH groups at both ends of the molecule is not limited to any compound having OH groups at both ends of Rf', but for example, HO-CH2-Rf'-CH2-OH can be given. Here, Rf' is the same as Rf' in formula (2) above. A more specific example of the perfluoropolyether (A) having OH groups at both ends of the molecule is, but is not limited to this, for example, HOCH2CF2O(CF2CF2O) c’ CF2CH2OH, HOCH2CF2CF2O(CF2CF2CF2O) d’ Examples include CF2CF2CH2OH. Here, the value of c' is preferably 1 to 25, more preferably 4 to 14, and the value of d' is preferably 1 to 20, more preferably 2 to 12. The values ​​of c' and d' were determined using the method described above with a JEOL JNM-ECX400. 19 This value was calculated by F-NMR measurement.

[0063] The number-average molecular weight of the perfluoropolyether (A) having OH groups at both ends of the molecule is not limited to this, but is preferably 150 to 6000, more preferably 400 to 2500, and even more preferably 500 to 1200. Here, the number-average molecular weight is determined by the method described above using a JEOL JNM-ECX400. 19 These values ​​were measured by 1F-NMR.

[0064] The perfluoropolyether (A) having OH groups at both ends of the above molecule is a compound having a molecular weight distribution, and its molecular weight distribution (PD), expressed as weight-average molecular weight / number-average molecular weight, is preferably 1.0 to 1.5, more preferably 1.0 to 1.3, and even more preferably 1.0 to 1.1. This molecular weight distribution is a characteristic value obtained using a Tosoh HPLC-8220GPC with a Polymer Laboratory column (PLgel Mixed E), an HCFC-based fluorocarbon substitute as the eluent, and an unfunctional perfluoropolyether as the reference substance.

[0065] As the epoxide derivative having the OH group and / or cyclic hydrocarbon group, it reacts with a perfluoropolyether (A) having OH groups at both ends of the molecule, R 11 -Rf'-R 12 The epoxide derivatives that form the OH group are not particularly limited. Examples of epoxide derivatives having the OH group include glycidol, 3-(2-oxyranylmethoxy)-1,2-propanediol, and 2-(2-oxyranylmethoxy)ethanol. Examples of epoxide derivatives having the cyclic hydrocarbon group include 2-[(4-methoxyphenoxy)methyl]oxirane, 2-[(4-ethoxyphenoxy)methyl]oxirane, 2-[(4-propoxyphenoxy)methyl]oxirane, 2-[(4-butoxyphenoxy)methyl]oxirane, 2-[(4-nitrophenoxy)methyl]oxirane, and 2-[(phenoxy)methyl]oxirane.

[0066] Here, the amount of epoxide derivative having an OH group and / or a cyclic hydrocarbon group used is preferably 150 mol% to 300 mol%, and more preferably 200 mol% to 250 mol%, relative to the perfluoropolyether (A) having an OH group at both ends of the molecule. If the amount of epoxide derivative having an OH group and / or a cyclic hydrocarbon group used is within the above range, the desired perfluoropolyether derivative can be obtained.

[0067] The reaction between a perfluoropolyether (A) having OH groups at both ends of the molecule and an epoxide derivative having OH groups and / or cyclic hydrocarbon groups is preferably carried out in the presence of a base. Potassium t-butoxide, sodium t-butoxide, sodium hydroxide, potassium hydroxide, etc., can be used as the base. The reaction temperature is preferably 25°C to 110°C, more preferably 40°C to 80°C. The reaction time is preferably 2 hours to 48 hours, more preferably 10 hours to 24 hours.

[0068] The above reaction is more preferably carried out under an inert gas atmosphere such as argon, nitrogen, or helium. Alternatively, the reaction may be carried out in a solvent. Suitable solvents include dichloromethane, t-butyl alcohol, toluene, dimethyl sulfoxide, and tetrahydrofuran.

[0069] A perfluoropolyether (A) having OH groups at both ends of the molecule can be reacted with an epoxide derivative having an OH group and / or a cyclic hydrocarbon group. The reaction is then neutralized with an acid such as hydrochloric acid, nitric acid, or sulfuric acid, washed with water, dehydrated, and purified by silica gel chromatography or the like to obtain a perfluoropolyether derivative in formula (2) in which p and q are 0.

[0070] (Manufacturing method (2)) In formula (2), the perfluoropolyether derivative R is one in which p is 0 and q is 1 or greater. 11 -Rf'-(L 13 -Rf') q -R 12As a method of producing the product, for example, (i) a perfluoropolyether (A) having OH groups at both ends of the molecule is reacted with a predetermined amount of an epoxide derivative having OH groups and / or cyclic hydrocarbon groups, so that the OH group at one end of the perfluoropolyether (A) reacts with the epoxide derivative and R is formed at one end of the perfluoropolyether (A). 11 A compound to which is bonded, and R at one end of the perfluoropolyether (A). 12 A step to obtain a compound to which is bonded, and the compound obtained in (ii)(i), and the linking group L 13 A compound having a structure that reacts with and binds to OH groups at both ends is reacted with a perfluoropolyether derivative R 11 -Rf'-(L 13 -Rf') q -R 12 Examples include a manufacturing method that includes the process of obtaining [the product]. Processes (i) and (ii) are described below.

[0071] In step (i), the reaction between a perfluoropolyether (A) having OH groups at both ends of the molecule and an epoxide derivative having a predetermined amount of OH groups and / or cyclic hydrocarbon groups is preferably carried out in the presence of a base. In step (i), the perfluoropolyether (A) having OH groups at both ends of the molecule of the starting material, the epoxide derivative having OH groups and / or cyclic hydrocarbon groups, the base, reaction temperature, reaction time, reaction atmosphere, and solvent are the same as in "Production Method (1)" described above.

[0072] In step (i), the amount of epoxide derivative having an OH group and / or a cyclic hydrocarbon group used is preferably 10 mol% to 80 mol%, more preferably 20 mol% to 60 mol%, relative to the perfluoropolyether (A) having OH groups at both ends of the molecule. If the amount of epoxide derivative having an OH group and / or a cyclic hydrocarbon group used is within the above range, then the desired R group is added to one end of the perfluoropolyether (A). 11 or R 12 A perfluoropolyether derivative to which is bonded can be obtained.

[0073] The linking group L used in process (ii) 13 Examples of compounds having a structure in which OH groups react and bond to both ends of the linking group L 13 Examples of such compounds include diepoxide compounds having epoxide structures at both ends of a hydrocarbon group, and α,ω-dihaloalkyl alcohol compounds. Examples of such diepoxide compounds include 1,3-butadiene diepoxide, 1,4-pentadiene diepoxide, 1,5-hexadiene diepoxide, 1,6-heptadiene diepoxide, 1,7-octadiene diepoxide, 1,8-nonanediene diepoxide, and 1,9-decanediene diepoxide. Here, the linking group L 13 The amount of compound used that has a structure that reacts with and bonds to OH groups at both ends of (i) is preferably 40 mol% to 280 mol%, more preferably 80 mol% to 240 mol%, relative to the perfluoropolyether derivative obtained in (i). Linking group L 13 If the amount of compound having a structure that reacts with and bonds to OH groups at both ends is within the aforementioned range, a desired perfluoropolyether derivative can be obtained.

[0074] In step (ii), the compound obtained in (i) and the linking group L 13 The reaction with a compound having a structure that reacts with and binds to OH groups at both ends is preferably carried out in the presence of a base. Potassium t-butoxide, sodium t-butoxide, sodium hydroxide, potassium hydroxide, etc., can be used as the base. The reaction temperature is preferably 25°C to 110°C, more preferably 40°C to 80°C. The reaction time is preferably 2 hours to 48 hours, more preferably 10 hours to 24 hours.

[0075] The above reaction is more preferably carried out under an inert gas atmosphere such as argon, nitrogen, or helium. Alternatively, the reaction may be carried out in a solvent. Suitable solvents include t-butanol, toluene, and xylene.

[0076] The perfluoropolyether derivative obtained in (i) above, and the linking group L 13 After reacting a compound having a structure that reacts with and binds to OH groups at both ends, the reaction is neutralized with an acid such as hydrochloric acid, nitric acid, or sulfuric acid, followed by washing with water and dehydration, and then purified by silica gel chromatography or the like to obtain a perfluoropolyether derivative R in formula (2) where p is 0 and q is 1 or more. 11 -Rf'-(L 13 -Rf') q -R 12 This can be obtained. The value of q is obtained using the method described above with JEOL's JNM-ECX400. 1 This is an average value calculated by 1H-NMR measurement, and is a real number.

[0077] (Manufacturing method (3)) As a method for producing a perfluoropolyether derivative in formula (2) where p=1, q=0, and x=1 and y=1, or x=2 and y=0, for example, (i) react a perfluoropolyether (A) having OH groups at both ends of the molecule with a predetermined amount of an epoxide derivative having OH groups and / or cyclic hydrocarbon groups, so that the OH group at one end of the perfluoropolyether (A) reacts with the epoxide derivative and R is formed at one end of the perfluoropolyether (A) 11 , R 12 or R 13 The process of obtaining a compound in which each of the following is bonded, and the compound obtained in (ii)(i) and the linking group L 11 -C(L 14 ) x (R 14 ) y -L 12 L 11 , L 14 and L 12 A compound having a structure that reacts with and binds to each terminal of is reacted with a perfluoropolyether derivative R 11 -Rf'-L 11 -C(L 14 ) x (R 14 ) y -L 12 -Rf'-R 12Examples include a manufacturing method that includes the process of obtaining [the product]. Processes (i) and (ii) are described below.

[0078] In step (i), the reaction between a perfluoropolyether (A) having OH groups at both ends of the molecule and an epoxide derivative having a predetermined amount of OH groups and / or cyclic hydrocarbon groups is preferably carried out in the presence of a base. In step (i), the perfluoropolyether (A) having OH groups at both ends of the molecule of the starting material, the epoxide derivative having OH groups and / or cyclic hydrocarbon groups, the base, reaction temperature, reaction time, reaction atmosphere, and solvent are the same as in "Production Method (1)" described above.

[0079] In step (i), the amount of epoxide derivative having an OH group and / or a cyclic hydrocarbon group used is 10 mol% to 80 mol%, more preferably 20 mol% to 60 mol%, relative to the perfluoropolyether (A) having OH groups at both ends of the molecule. If the amount of epoxide derivative having an OH group and / or a cyclic hydrocarbon group used is within the above range, then the desired perfluoropolyether (A) has R at one end. 11 , R 12 or R 13 A perfluoropolyether derivative to which is bonded can be obtained.

[0080] The linking group L used in process (ii) 11 -C(L 14 ) x (R 14 ) y -L 12 L 11 , L 14 and L 12 Compounds having a structure in which an OH group reacts and bonds to each of the terminals are not limited to this, but for example, the following formula (9) [ka] Represented by 2,2'-[[2-ethyl-2-[(2-oxyranylmethoxy)methyl]-1,3-propanediyl]bis(oxymethylene)]bis-oxirane, shown in formula (10) below. [ka] Examples include 2,2'-[[2,2-bis[(2-oxyranylmethoxy)methyl]-1,3-propanediyl]bis(oxymethylene)]bis-oxiran, which are represented by the linking group L. 11 -C(L 14 ) x (R 14 ) y -L 12 L 11 , L 14 and L 12 The amount of compound used that has a structure that reacts with and bonds to an OH group at each end is preferably 10 mol% to 150 mol%, more preferably 10 mol% to 50 mol%, relative to the compound obtained in (i). If the amount used is within the above range, the desired perfluoropolyether derivative can be obtained.

[0081] In step (ii), the compound obtained in (i) and the linking group L 11 -C(L 14 ) x (R 14 ) y -L 12 L 11 , L 14 and L 12 The reaction with compounds having a structure that reacts with and bonds to an OH group at each end is preferably carried out in the presence of a base. Potassium t-butoxide, sodium t-butoxide, sodium hydroxide, potassium hydroxide, etc., can be used as the base. The reaction temperature is preferably 25°C to 110°C, more preferably 40°C to 80°C. The reaction time is preferably 2 hours to 48 hours, more preferably 10 hours to 24 hours.

[0082] The above reaction is more preferably carried out under an inert gas atmosphere such as argon, nitrogen, or helium. Alternatively, the reaction may be carried out in a solvent. Suitable solvents include t-butanol, toluene, xylene, and metaxylene hexafluoride.

[0083] The compound obtained in (i) above, and the linking group L 11 -C(L 14 ) x (R 14 ) y -L 12 L 11 , L 14 and L 12 After reacting a compound having a structure that reacts with and binds to each terminal of the hydroxyl group, the reaction is neutralized with an acid such as hydrochloric acid, nitric acid, or sulfuric acid, followed by washing with water, dehydration, and purification by silica gel chromatography or the like to obtain a perfluoropolyether derivative in formula (2) where p=1, q=0, and x=1 and y=1, or x=2 and y=0.

[0084] <Esterification process> In this process, an ester is introduced into the compound represented by formula (2) (perfluoropolyether derivative) to obtain a perfluoropolyether derivative ester. One method for introducing the ester is to react the perfluoropolyether derivative with an acid anhydride in the presence of a base.

[0085] Examples of acid anhydrides that can be used include acetic anhydride and propionic anhydride. Furthermore, examples of bases that can be used include pyridine and triethylamine.

[0086] By reacting the perfluoropolyether derivative with an acid anhydride in the presence of a base, the OH group of the perfluoropolyether derivative is esterified, thereby protecting the OH group of the perfluoropolyether derivative in the fluorination step described later.

[0087] The reaction temperature for the above reaction is, for example, 0°C to 60°C, more preferably 15°C to 40°C. The reaction time for the above reaction is preferably 3 hours to 48 hours, more preferably 5 hours to 20 hours.

[0088] The perfluoropolyether derivative ester can be purified by reacting the perfluoropolyether derivative with an acid anhydride, and then removing the base and acid under reduced pressure, for example. The temperature for reduced pressure distillation is preferably 60°C to 80°C, more preferably 65°C to 75°C.

[0089] <Fluorination process> In this step, the perfluoropolyether derivative ester obtained in the esterification step is fluorinated. In this step, the method for fluorinating the perfluoropolyether derivative ester is not particularly limited, but for example, a method can be given that includes a step of introducing the perfluoropolyether derivative ester, fluorine gas, an inert gas, and a solvent into a reactor and reacting them (step I), and a step of introducing an alcohol into the reactor after step I (step II).

[0090] In the above method, it can also be said that fluorination is carried out in a liquid-phase fluorine substitution reactor. Here, fluorination, i.e., the fluorine substitution reaction, is preferably carried out using a fully halogenated liquid, such as perfluorocarbons, fully halogenated chlorofluorocarbons, or fully halogenated chlorofluoroethers, as the solvent. The solvent is not limited to these, but for example, 1,1,2-chlorotrifluoroethane can be used.

[0091] Step I is not particularly limited as long as it is a step of introducing the perfluoropolyether derivative ester, fluorine gas, inert gas, and solvent into a reactor and reacting them, but for example, it can be carried out by the following procedure. i) Introduce the solvent into the reactor. ii) Dilute the perfluoropolyether derivative ester with the solvent and introduce it into the reactor at an appropriate rate. iii) Fluorine gas and inert gas are introduced into the reactor.

[0092] In i) above, it is more preferable to replace the air inside the reactor with an inert gas by purging the reactor with an inert gas before starting the reaction. The inert gas is not particularly limited, but examples include nitrogen, helium, argon, etc. The time for purging the reactor is also not limited, but for example it is 10 minutes to 2 hours, and more preferably 20 minutes to 40 minutes.

[0093] The temperature inside the reactor is preferably -40°C to 150°C, and more preferably -10°C to 50°C, during the reaction. It is even more preferable to maintain the temperature inside the reactor within the above range throughout the fluorine substitution reaction.

[0094] In ii) above, the solvent used to dilute the perfluoropolyether derivative ester may be any of the aforementioned solvents. Furthermore, the solvent used to dilute the perfluoropolyether derivative ester and the solvent introduced into the reactor in i) above may be the same or different, but from the viewpoint of ease of removal, it is more preferable that they be the same solvent.

[0095] The dilution ratio for diluting the perfluoropolyether derivative ester with the solvent is not particularly limited, but for example, the amount of the perfluoropolyether derivative ester relative to the total amount of the perfluoropolyether derivative ester and solvent after dilution is 10% to 80% by mass, and more preferably 20% to 50% by mass.

[0096] Furthermore, the rate at which the perfluoropolyether derivative ester diluted with the solvent is introduced into the reactor is not particularly limited and can be appropriately selected depending on the size of the reactor, the amount of the perfluoropolyether derivative ester, fluorine gas, inert gas, and solvent.

[0097] The amount of fluorine gas introduced in iii) above is not particularly limited, but is, for example, 1 to 5 equivalents, more preferably 1 to 1.5 equivalents, of the hydrogen atoms to be fluorinated. This step is usually used to fluorine-substituted all hydrogen atoms in a molecule, but when fluorine-substituted only some of the hydrogen atoms in a molecule, a fluoropolyter compound in which some of the hydrogen atoms in the molecule have been fluorine-substituted can be obtained by introducing an amount of fluorine gas equivalent to the amount of hydrogen atoms to be fluorine-substituted.

[0098] In step I, a hydrogen fluoride scavenger may be used to capture the hydrogen fluoride produced during the reaction. For example, sodium fluoride can be used as the hydrogen fluoride scavenger. The method of adding the hydrogen fluoride scavenger is not particularly limited, but for example, it can be introduced into the reactor together with the solvent in i) above.

[0099] In step II, an alcohol is introduced into the reactor after step I. More specifically, for example, the alcohol is introduced into the reactor after the introduction of fluorine gas is completed in step I. The alcohol is not limited to these, but examples include methanol, ethanol, n-propanol, etc., and methanol is particularly preferred due to its ease of purification. The amount of alcohol introduced is, for example, 2 to 20 times, more preferably 2 to 5 times, the volume of the perfluoropolyether derivative ester.

[0100] After introducing alcohol into the reactor in step II, the purified fluorinated perfluoropolyether derivative ester can be obtained, for example, by filtering the reaction mixture to remove the solid component and concentrating the liquid component.

[0101] <Restoration Process> In this step, the fluorinated perfluoropolyether derivative ester (hereinafter sometimes simply referred to as "fluorinated ester") obtained in the fluorination step is reduced. The method for reducing the fluorinated ester obtained in the fluorination step is not limited to this, but for example, a method of reducing the fluorinated ester with borohydride metal can be mentioned.

[0102] The method for reducing the fluorinated ester with borohydride metal is not particularly limited, but one example is to add the fluorinated ester obtained in the fluorination step dropwise to a mixture of an alcohol and a borohydride metal compound. It is more preferable to add the fluorinated ester dropwise while stirring the mixture of the alcohol and the borohydride metal compound. It is also more preferable that the fluorinated ester is added dropwise after being diluted with a fluorine solvent.

[0103] The reaction temperature for the reduction step is, for example, -10°C to 80°C, more preferably 0°C to 50°C, and the reaction time is, for example, 2 hours to 24 hours, more preferably 10 to 20 hours.

[0104] Suitable fluorine solvents include, for example, Novec 7100, Novec 7200, PF-5060, and PF-5080 from 3M; and Vertrel XF from Mitsui Chemours Fluoroproducts. Among these, Novec 7100 is particularly preferred in terms of substrate solubility and chemical stability.

[0105] The aforementioned alcohol can be selected from, for example, alcohols having 1 to 10 carbon atoms, with ethanol being particularly preferred in terms of substrate solubility and handling.

[0106] The borohydride metal can be selected from, for example, alkali metal salts of borohydride and alkaline earth metal salts of borohydride, with sodium borohydride being particularly preferred from a safety standpoint.

[0107] The obtained product can be extracted from the aqueous layer using a fluorinated solvent after the fluorinated ester has been reacted with a borohydride metal, for example by adding hydrochloric acid to stop the reaction. By concentrating this fluorinated solvent layer and purifying it by distillation and / or silica gel chromatography, the target compound, a fluoropolyether compound, can be obtained in which the terminal groups have been reduced to alcohols.

[0108] <2.2 Method for fluorinating polyalkylene glycol derivative esters> The following describes a method for producing a fluoropolyether compound according to another embodiment of the present invention, which involves fluorinating a polyalkylene glycol derivative ester. The method for producing a fluoropolyether compound according to this embodiment includes, for example, an esterification step of introducing an ester into a compound represented by the following formula (3) (hereinafter sometimes referred to as "polyalkylene glycol derivative"), a fluorination step of fluorinating the ester obtained in the esterification step, and a reduction step of reducing the fluorinated ester obtained in the fluorination step. [ka] In formula (3), Rf'' is a polyoxyalkylene group, and R 21 and R 22 This is a hydrocarbon group or OH group, which may contain an ether bond having one or more OH groups.

[0109] In equation (3), Rf'' is a group in which all the fluorine atoms of Rf' in equation (2) above are replaced by hydrogen atoms.

[0110] The polyalkylene glycol derivative is not particularly limited as long as it is a compound represented by formula (3). 21 and R 22 When is an OH group, the compound represented by formula (3) may be a polyalkylene glycol such as methylene glycol, ethylene glycol, propylene glycol, or butylene glycol. 21and R 22 This is R in equations (1) and (2) mentioned above. 1 , R 2 , R 11 , or R 12 It could be the same as this.

[0111] <Esterification process> In this process, an ester is introduced into the polyalkylene glycol derivative to obtain a polyalkylene glycol derivative ester. Methods for introducing the ester include, for example, substituting the OH group of the polyalkylene glycol derivative with a leaving group and reacting it with a malonic acid diester, or reacting the polyalkylene glycol derivative with an acid anhydride in the presence of a base.

[0112] Examples of leaving groups that substitute for the OH group of the polyalkylene glycol derivative include p-toluenesulfonyl group, trifluoromethylsulfonyl group, methanesulfonyl group, iodine group, bromo group, and chloro group. The method for introducing the leaving group into the polyalkylene glycol derivative is not particularly limited, and conventionally known methods can be used as appropriate. An example of a compound in which leaving groups are introduced to both ends of the polyalkylene glycol derivative is Ts-CH2CH2O(CH2CH2O) z Examples of compounds represented by CH2CH2-Ts can be cited, where Ts is a tosyl group. z is preferably a real number between 1 and 25, and more preferably an integer between 4 and 14. z was measured using JEOL's JNM-ECX400. 1 This is the average value calculated by 1H-NMR measurement. In the NMR measurement, the sample was diluted with deuterated chloroform before measurement.

[0113] The method for reacting a compound in which leaving groups are introduced at both ends of the polyalkylene glycol derivative with a malonic acid diester is not particularly limited, but one method is to react the polyalkylene glycol derivative with the malonic acid diester in the presence of a base. For example, diethyl malonate and dimethyl malonate can be used as the malonic acid diester. For example, potassium t-butoxide, sodium t-butoxide, sodium hydroxide, potassium hydroxide, etc. can be used as the base. The reaction temperature is preferably 0°C to 100°C, more preferably 40°C to 80°C. The reaction time is preferably 2 hours to 24 hours, more preferably 5 hours to 20 hours. As a result, the leaving groups of the polyalkylene glycol derivative are removed and the ester is introduced.

[0114] The above reaction is more preferably carried out under an inert gas atmosphere such as argon, nitrogen, or helium. Alternatively, the reaction may be carried out in a solvent. Suitable solvents include dichloromethane, t-butyl alcohol, toluene, dimethyl sulfoxide, and tetrahydrofuran.

[0115] The compound obtained by introducing leaving groups to both ends of the polyalkylene glycol derivative is reacted with a malonic acid diester to obtain a polyalkylene glycol derivative ester. This ester can then be neutralized with an acid such as ammonium chloride, washed with water, dehydrated, and purified by silica gel chromatography or the like.

[0116] The method for reacting the polyalkylene glycol derivative with the acid anhydride in the presence of a base is the same as the esterification step described in [2.1 Method for fluorinating perfluoropolyether derivative esters] above.

[0117] <Fluorination process, reduction process> The fluorination and reduction steps are the same as in the case of [2.1 Method for fluorinating perfluoropolyether derivative esters], so their explanation is omitted here.

[0118] [3. Lubricants] A lubricant according to one embodiment of the present invention includes the fluoropolyether compound according to the aforementioned embodiment of the present invention. The fluoropolyether compound can be used alone as a lubricant, or the lubricant can be used by mixing the fluoropolyether compound with other components in any ratio, as long as it does not impair its performance.

[0119] Other components mentioned above include known magnetic disk lubricants such as Fomblin® Zdol (manufactured by Solvay Solexis), Ztetraol (manufactured by Solvay Solexis), Demnum® (manufactured by Daikin Industries), Krytox® (manufactured by Dupont), and MORESCO PHOSFAROL A20H (manufactured by MORESCO), MORESCO PHOSFAROL D-4OH (manufactured by MORESCO), etc.

[0120] This lubricant can be used as a lubricant for recording media to improve the sliding characteristics of magnetic disks. It can also be used as a lubricant for recording media in other recording devices where sliding occurs between the recording medium and the head, such as magnetic tape. Furthermore, it can be used as a lubricant for equipment with sliding parts, not limited to recording devices.

[0121] [4. Magnetic disks] A magnetic disk 1 according to one embodiment of the present invention includes a recording layer 4, a protective film layer (protective layer) 3, and a lubricating layer 2 disposed on a non-magnetic substrate 8, as shown in Figure 1. The lubricating layer 2 contains the lubricant described above.

[0122] In other embodiments, the magnetic disk may include, as shown in Figure 2, a lower layer 5 placed beneath the recording layer 4, one or more soft magnetic lower layers 6 placed beneath the lower layer 5, and an adhesive layer 7 placed beneath the one or more soft magnetic lower layers 6. In one embodiment, all of these layers may be formed on a non-magnetic substrate 8.

[0123] Each layer of the magnetic disk 1 other than the lubricating layer 2 can contain materials known in the art as being suitable for individual layers of magnetic disks. For example, as materials for the recording layer 4, there can be mentioned alloys obtained by adding chromium, platinum, tantalum, etc. to elements capable of forming ferromagnetic substances such as iron, cobalt, nickel, etc., or oxides thereof. Also, as materials for the protective layer 3, there can be mentioned carbon, Si3N4, SiC, SiO2, etc. As materials for the non-magnetic substrate 8, there can be mentioned aluminum alloys, glass, polycarbonate, etc.

[0124] 〔5. Method for manufacturing a magnetic disk〕 The method for manufacturing a magnetic disk according to one aspect of the present invention includes a step of forming a lubricating layer by laminating a lubricant according to one embodiment of the present invention on the exposed surface of the protective layer of a laminate in which a recording layer and a protective layer are laminated.

[0125] The method of laminating the lubricant on the exposed surface of the protective layer of the laminate in which the recording layer and the protective layer are laminated to form a lubricating layer is not particularly limited. As a method of laminating the lubricant on the exposed surface of the protective layer, a method of laminating by immersing the magnetic disk in a liquid in which the lubricant is diluted with a solvent is preferable. Examples of the solvent include PF-5060, PF-5080, Novec7100, Novec7200 manufactured by 3M, Vertrel-XF (registered trademark) manufactured by DuPont, etc. The concentration of the lubricant after dilution with the solvent is preferably 0.001 wt% to 1 wt%, more preferably 0.005 wt% to 0.5 wt%, and even more preferably 0.005 wt% to 0.1 wt%. If the concentration of the lubricant after dilution with the solvent is 0.005 wt% to 0.1 wt%, the interaction between lubricant molecules can be weakened, and it is easy to form a uniform lubricating film.

[0126] The recording layer and the protective layer may be formed in this order, and after laminating the lubricant on the exposed surface of the protective layer, ultraviolet irradiation or heat treatment may be performed.

[0127] By performing ultraviolet irradiation or heat treatment, a stronger bond can be formed between the exposed surfaces of the lubricating layer and the protective layer, and evaporation of the lubricant due to heating can be prevented. When performing ultraviolet irradiation, it is preferable to use ultraviolet light having a wavelength of 185 nm or 254 nm as the main wavelength. When performing heat treatment, the temperature is preferably 60 to 170 °C, more preferably 80 to 170 °C, and even more preferably 80 to 150 °C.

[0128] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Example

[0129] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[0130] 〔Example 1: Synthesis of HOCH2CH(OH)CF2OCF2CF2O(CF2CF2O) c’ CF2CF2OCF2CH(OH)CH2OH (Compound 1)〕 Under an argon atmosphere, 500 g of HOCH2CF2O(CF2CF2O) c’ CF2CH2OH (number average molecular weight 1048), 94 g of glycidol, and 11 g of potassium t-butoxide were stirred in a solvent (243 g of t-butyl alcohol) at 70 °C for 22 hours to obtain a crude product. Then, 60 g of a 3% aqueous nitric acid solution was added to the obtained mixture containing the crude product for neutralization, followed by washing with water and dehydration. The obtained crude product was purified by silica gel chromatography to obtain 513 g of the following Compound 1-2 in which the OH group at the terminal of the perfluoropolyether was replaced with a dihydroxypropoxy group.

Chemical formula

[0131] 1.9 L of 1,1,2-trichlorotrifluoroethane and 1320 g of sodium fluoride were placed in a 5 L reaction vessel. 300 g of the compound with the acetylated OH group was diluted with 1,1,2-trichlorotrifluoroethane to a volume of 710 mL. The nitrogen flow into the reaction vessel was set to 3400 mL / min and the fluorine flow into the reaction vessel was set to 800 mL / min. While maintaining the temperature of the reaction vessel at 0°C, the compound with the acetylated OH group, diluted with 1,1,2-trichlorotrifluoroethane, was added to the reaction vessel at a rate of 0.5 mL / min. After adding the diluent, the nitrogen flow was reduced to 1500 mL / min and the fluorine flow to 300 mL / min. While maintaining the temperature of the reaction vessel at 0°C, an appropriate amount of fluorine was introduced while maintaining these nitrogen and fluorine flows for 30 minutes, and then the introduction of fluorine was stopped. Next, the reaction vessel was purged with nitrogen, and then 112 g of methanol was added to the reaction vessel. The solid was filtered off from the resulting reaction mixture, the filtrate was concentrated, and purified by distillation to obtain 420 g of a perfluoro compound with methyl esterified ends.

[0132] A mixed solution of 91 g of sodium borohydride and 800 g of ethanol was placed in a 4 L four-necked flask. 400 g of a perfluoro compound with methyl-esterified terminals, diluted with 800 g of Novec 7100 (3M), was added dropwise to the four-necked flask at a rate of 5 g / min, and the mixture was stirred at 40°C for 16 hours. 400 g of 3% hydrochloric acid was added to the four-necked flask to stop the reaction, and the target compound dissolved in Novec 7100 was separated and extracted from the aqueous layer. The crude product was obtained by concentrating and drying the extract layer. The crude product was then purified by column chromatography and distillation to obtain 118 g of compound 1, in which the terminal groups were reduced to alcohol groups. Compound 1 is a white, waxy solid with a density of 1.7 g / cm³ at 20°C. 3 The following results were obtained by performing NMR measurements on compound 1 and identifying its structure. 19 F-NMR (solvent: deuterium methanol, reference: OCF2CF2O in the product is set to -89.1 ppm). δ=-80.6ppm [2F], δ=-81.5ppm [2F], δ=-89.1ppm [31F] 19 F-NMR results showed that c = 6.1 in compound 1.

[0133] 1 1H-NMR (solvent: deuterium methanol, reference substance: residual protons in deuterium methanol) δ=3.6ppm[2H], δ=3.7ppm[2H], δ=4.0ppm[2H]. Furthermore, the repeating unit c in formula (4) of compound 1 is 2 greater than the repeating unit c' in formula (4') of the starting material compound 1-2.

[0134] [Example 2: (HOCH2)2CFCF2CF2OCF2CF2O(CF2CF2O) c’ Synthesis of CF2CF2OCF2CF2CF(CH2OH)2 (Compound 2) Under an argon atmosphere, HO(CH2CH2O) is dissolved in a solvent (600g of dichloromethane). c’300 g of H (number-average molecular weight 533) and 171 g of triethylamine were mixed at 0°C, to which 255 g of p-toluenesulfonyl chloride diluted with 800 g of dichloromethane was added dropwise. After addition, the resulting mixture was reacted at room temperature for 15 hours, and then 300 mL of saturated sodium bicarbonate aqueous solution was added. Subsequently, the resulting crude product was washed with water, dehydrated, and purified by silica gel column chromatography to obtain 345 g of tosyl-terminated polyethylene glycol.

[0135] Under an argon atmosphere, 300 g of tosyl-terminated polyethylene glycol was added dropwise to a mixture of 675 g of t-butyl alcohol, 43 g of potassium t-butoxide, and 59 g of diethyl malonate, and the mixture was stirred at 70°C for 15 hours. To the resulting reaction mixture, 600 mL of saturated ammonium chloride aqueous solution and 525 g of dichloromethane were added, washed with water, dehydrated, and purified by silica gel column chromatography to obtain 154 g of polyethylene glycol derivative ester.

[0136] 900 mL of 1,1,2-trichlorotrifluoroethane and 615 g of sodium fluoride were placed in a 3 L reaction vessel. 140 g of the polyethylene glycol derivative ester was diluted with 1,1,2-trichlorotrifluoroethane to a volume of 350 mL. The nitrogen flow into the reaction vessel was set to 3400 mL / min, and the fluorine flow into the reaction vessel was set to 800 mL / min. While maintaining the temperature of the reaction vessel at 0°C, the polyethylene glycol derivative ester diluted with 1,1,2-trichlorotrifluoroethane was added to the reaction vessel at a rate of 0.5 mL / min. After adding the diluted solution, the nitrogen flow was reduced to 1500 mL / min, and the fluorine flow was reduced to 300 mL / min. While maintaining the temperature of the reaction vessel at 0°C, the nitrogen and fluorine flows were maintained for 30 minutes, and after introducing an appropriate amount of fluorine, the introduction of fluorine was stopped. Next, the reaction vessel was purged with nitrogen, and then 53 g of methanol was added to the reaction vessel. The solid was filtered off from the resulting reaction mixture, the filtrate was concentrated, and purified by distillation to obtain 95 g of a perfluoro compound with methyl esterified ends.

[0137] 21 g of sodium borohydride and 190 g of ethanol were placed in a 1 L four-necked flask. 95 g of a perfluoro compound with methyl-esterified terminals, diluted with 200 g of Novec 7100, was added dropwise to the four-necked flask at a rate of 5 g / min, and the mixture was stirred at 40°C for 16 hours. 95 g of 3% hydrochloric acid was added to the four-necked flask to stop the reaction, and the target compound dissolved in Novec 7100 was separated and extracted from the aqueous layer. The crude product was obtained by concentrating and drying the extract layer. The crude product was then purified by column chromatography and distillation to obtain 33 g of compound 2, in which the terminal groups were reduced to alcohol groups. The obtained compound 2 was a white, waxy solid with a density of 1.7 g / cm³ at 20°C. 3 The results were as follows. NMR measurements were performed on compound 2, and its structure was identified based on the following findings.

[0138] 19 F-NMR (solvent: none, reference: OCF2CF2O in the product is set to -89.1 ppm) δ=-83.0ppm [4F], δ=-89.1ppm [44F], δ=-123.7ppm [4F], δ=-184.1ppm [2F] 19 F-NMR results showed that c = 9.2 in compound 2.

[0139] 1 1H-NMR (solvent: none, reference substance: residual protons in heavy water) δ = 3.0-3.9 ppm [6H] [Example 3: HOCH2CH(OH)CF2OCF2CF2O(CF2CF2O)] c’ CF2CF2OCF2CH(OH)CF2CF2CF2CF2CH(OH)CF2OCF2CF2O(CF2CF2O) c’ Synthesis of CF2CF2OCF2CH(OH)CH2OH (Compound 3) Under an argon atmosphere, HOCH2CF2O(CF2CF2O) c’1968 g of CF2CH2OH (number average molecular weight 980) and 70 g of glycidol were stirred in the presence of 10 g of potassium t-butoxide in a solvent (410 g of t-butyl alcohol) at 70°C for 14 hours to obtain a crude product. The crude product was then washed with water, dehydrated, and purified by silica gel column chromatography to obtain 950 g of a perfluoropolyether having one hydroxyl group at one end and two hydroxyl groups at the other end (in which the OH group at one end of the starting material perfluoropolyether was replaced with a dihydroxypropoxy group). 940 g of this perfluoropolyether and 63 g of 1,7-octadiene diepoxide were stirred in the presence of 10 g of sodium t-butoxide in a solvent (410 g of t-butyl alcohol) at 70°C for 14 hours to obtain a crude product. Subsequently, the crude product obtained was washed with water, dehydrated, and purified by distillation to obtain 610 g of a perfluoropolyether derivative (compound 3-2 below). [ka] 512 g of this perfluoropolyether derivative (compound 3-2) was placed in a round-bottom flask, and 385 g of pyridine was added while stirring. 445 g of acetic anhydride was added dropwise to the resulting mixture, and the mixture was stirred overnight at room temperature. The reaction mixture was then concentrated and dried using an evaporator to obtain 519 g of the compound in which the OH group had been acetylated.

[0140] 3.2 L of 1,1,2-trichlorotrifluoroethane and 2200 g of sodium fluoride were placed in a 10 L reaction vessel. 500 g of the compound in which the OH group was acetylated was diluted with 1,1,2-trichlorotrifluoroethane so that the volume after dilution was 1200 mL. The flow rate of nitrogen introduced into the reaction vessel was set to 3400 mL / min, and the flow rate of fluorine introduced into the reaction vessel was set to 800 mL / min. While maintaining the temperature of the reaction vessel at 0 °C, the compound in which the OH group was acetylated and diluted with 1,1,2-trichlorotrifluoroethane was added to the reaction vessel at a rate of 0.5 mL / min. After adding the dilution solution, the flow rate of nitrogen was reduced to 1500 mL / min, and the flow rate of fluorine was reduced to 300 mL / min. While maintaining the temperature of the reaction vessel at 0 °C, an appropriate amount of fluorine was introduced while maintaining these nitrogen and fluorine flow rates for 30 minutes, and then the introduction of fluorine was stopped. Subsequently, the reaction vessel was purged with nitrogen, and then 188 g of methanol was added to this reaction vessel. Solids were filtered off from the resulting reaction mixture, the filtrate was concentrated, and purified by distillation to obtain 296 g of a perfluorinated compound with a methyl esterified end.

[0141] A mixed solution of 49 g of sodium borohydride and 580 g of ethanol was placed in a 4 L four-necked flask. 290 g of the perfluorinated compound with a methyl esterified end, diluted with 580 g of Novec7100, was added dropwise to the above four-necked flask at a rate of 5 g / min, and then stirred at 40 °C for 16 hours. 290 g of 3% hydrochloric acid was added to the four-necked flask to stop the reaction, and the target compound dissolved in Novec7100 was separated and extracted from the aqueous layer. The extraction layer was concentrated and dried to obtain a crude product. Subsequently, the crude product was purified by column chromatography and distillation to obtain 145 g of Compound 3 in which the terminal group was reduced to an alcohol group. Compound 3 was a white gel, and its density at 20 °C was 1.8 g / cm 3 and was. NMR measurement of Compound 3 was performed, and the structure was identified based on the following results.

[0142] 19 F-NMR (solvent: none, reference substance: OCF2CF2O in the product is set to -89.1 ppm.) δ=-77.8~-80.1ppm [4F], δ=-82.7~-84.3ppm [4F], δ=-89.1ppm [80F], δ=-120.6~-128.2ppm [8F] 19 F-NMR results showed that compound 3 has a c value of 8.1.

[0143] 1 1H-NMR (solvent: none, reference substance: residual protons in heavy water) δ = 2.5~5.0 ppm [14H] [Example 4: HOCH2CH(OH)CF2OCF2CF2O(CF2CF2O)] c’ CF2CF2OCF2CH(OH)CF2OCF2C(CF2CF3)(CF2OCF2CH(OH)CF2OCF2CF2O(CF2CF2O) c’ CF2CF2OCF2CH(OH)CH2OH)CF2OCF2CH(OH)CF2OCF2CF2O(CF2CF2O) c’ Synthesis of CF2CF2OCF2CH(OH)CH2OH (Compound 4) Under an argon atmosphere, HOCH2CF2O(CF2CF2O) c’103 g of OCF2CH2OH (number average molecular weight 980) and 7 g of glycidol were stirred in the presence of 1 g of potassium t-butoxide in a solvent (44 g of t-butyl alcohol) at 70°C for 14 hours to obtain a crude product. The crude product was then washed with water, dehydrated, and further purified using silica gel column chromatography to obtain a perfluoropolyether having one OH group at one end and two OH groups at the other (in which the OH group at one end of the starting material perfluoropolyether was replaced with a dihydroxypropoxy group). This perfluoropolyether and 2,2'-[[2-ethyl-2-[(2-oxyranylmethoxy)methyl]-1,3-propanediyl]bis(oxymethylene)]bis-oxirane were stirred in the presence of 1 g of sodium t-butoxide in a solvent (t-butyl alcohol) at 70°C for 14 hours to obtain a crude product. Subsequently, the crude product obtained is washed with water, then dehydrated, and further purified by distillation to obtain a perfluoropolyether derivative (compound 4-2 below). [ka] Compound 4-2 was cetylated using the same method as in Example 3, an ester was introduced and fluorinated, and then reduced to obtain compound 4.

[0144] [Example 5: HOCH2CH(OH)CF2OCF2CF2O(CF2CF2O)] c’ CF2CF2OCF2CH(OH)CF2OCF2C(CF2OCF2CH(OH)CF2OCF2CF2O(CF2CF2O) c’ CF2CF2OCF2CH(OH)CH2OH)2CF2OCF2CH(OH)CF2OCF2CF2O(CF2CF2O) c’ Synthesis of CF2CF2OCF2CH(OH)CH2OH (Compound 5) Perfluoropolyether derivatives (compound 5-2 below) and compound 5 were obtained in the same manner as in Example 4, except that 2,2'-[[2,2-bis[(2-oxyranylmethoxy)methyl]-1,3-propanediyl]bis(oxymethylene)]bis-oxiran was used instead of 2,2'-[[2-ethyl-2-[(2-oxyranylmethoxy)methyl]-1,3-propanediyl]bis(oxymethylene)]bis-oxiran. [ka] [Example 6: CF3OC6F] 10 OCF2CH(OH)CF2OCF2CF2CF2O(CF2CF2CF2O) d’ CF2CF2CF2OCF2CH(OH)CF2CF2CF2CF2CH(OH)CF2OCF2CF2CF2O(CF2CF2CF2O) d’ CF2CF2CF2OCF2CH(OH)CF2OC6F 10 Synthesis of OCF3 (compound 6) Instead of glycidol, use 2-[(4-methoxyphenoxy)methyl]oxirane having the following structure: HOCH2CF2O(CF2CF2O) c’ Instead of OCF2CH2OH, use HOCH2CF2CF2O(CF2CF2CF2O) d’ A perfluoropolyether derivative (compound 6-2 below) and compound 6 were obtained in the same manner as in Example 3, except that CF2CF2CH2OH was used. [ka] [ka] [Comparative example 1: HOCH2CH(OH)CH2OCH2CF2O(CF2CF2O) c’ Synthesis of CF2CH2OCH2CH(OH)CH2OH (compounds 1-2) Compounds 1-2, obtained as synthetic intermediates in Example 1, in which each end of the perfluoropolyether was modified with a dihydroxypropoxy group, were used as the compounds for Comparative Example 1. Compounds 1-2 are white, waxy solids with a density of 1.7 g / cm³ at 20°C. 3 The following results were obtained by performing NMR measurements on compounds 1 and 2, and identifying their structures. 19 F-NMR (solvent: none, reference: OCF2CF2O in the product is set to -89.1 ppm.) δ=-78.0ppm [4F], δ=-89.1ppm [25F] 19 F-NMR results showed that c=6.3 in compound 1-2.

[0145] 1 1H-NMR (solvent: none, reference substance: residual protons in heavy water) δ=3.2-3.9ppm [14H], δ=4.1ppm [4H] [Comparative Example 2: (HOCH2)2CHCH2CH2OCH2CF2O(CF2CF2O) c’ Synthesis of CF2CH2OCH2CH2CH(CH2OH)2 (Compound 2-2) Under an argon atmosphere, HOCH2CF2O(CF2CF2O) c’ 211 g of CF2CH2OH (number average molecular weight 1590) and 58 g of 2-(2-bromoethyl)-1,3-propanediol were stirred in the presence of 33 g of potassium t-butoxide in a solvent (95 g of t-butyl alcohol) at 70°C for 14 hours to obtain a crude product. The crude product was then washed with water, dehydrated, and purified by silica gel chromatography to obtain 18 g of compound 2-2. [ka] Compound 2-2 is a white, waxy solid with a density of 1.7 g / cm³ at 20°C. 3 The following results were obtained by performing NMR measurements on compound 2-2 and identifying its structure. 19 F-NMR (solvent: none, reference: OCF2CF2O in the product is set to -89.1 ppm.) δ=-78.3ppm [4F], δ=-89.1ppm [36F] 19 F-NMR results showed that c=9.0 in compound 2-2.

[0146] 1H-NMR (Solvent: None, Reference material: Residual protons in heavy water) δ=1.7ppm [4H], δ=2.0ppm [2H], δ=3.1-3.9ppm [20H] [Comparative Example 3: HOCH2CH(OH)CH2OCH2CF2O(CF2CF2O) c’ CF2CH2OCH2CH(OH)CH2CH2CH2CH2CH(OH)CH2OCH2CF2O(CF2CF2O) c’ Synthesis of CF2CH2OCH2CH(OH)CH2OH (compound 3-2) The perfluoropolyether derivative (compound 3-2), which was an intermediate used in the synthesis of Example 3, was used as the compound for Comparative Example 3.

[0147] Compound 3-2 is a white, waxy solid with a density of 1.7 g / cm³ at 20°C. 3 The structure of compound 3-2 was identified by NMR measurement, based on the following results. 19 F-NMR (Solvent: None, Reference substance: OCF2CF2O in the product is set to -89.1 ppm.) δ=-79.0ppm [8F], δ=-89.1ppm [64F] 19 F-NMR results showed that the c value for compound 3-2 was 8.4.

[0148] 1H-NMR (Solvent: None, Reference material: Residual protons in heavy water) δ=1.3ppm [8H], δ=2.5~5.0ppm [30H] [Comparative Example 4: HOCH2CH(OH)CH2OCH2CF2O(CF2CF2O) c’ CF2CH2OCH2CH(OH)CH2OCH2C(CH2CH3)(CH2OCH2CH(OH)CH2OCH2CF2(OCF2CF2)c’ OCF2CH2OCH2CH(OH)CH2OH)CH2OCH2CH(OH)CH2OCH2CF2O(CF2CF2O) c’ Synthesis of CF2CH2OCH2CH(OH)CH2OH (Compound 4-2) The perfluoropolyether derivative (compound 4-2), which is an intermediate of Example 4, is used as the compound of Comparative Example 4.

[0149] [Comparative Example 5: HOCH2CH(OH)CH2OCH2CF2(OCF2CF2) c’ OCF2CH2OCH2CH(OH)CH2OCH2C(CH2OCH2CH(OH)CH2OCH2CF2(OCF2CF2) c’ OCF2CH2OCH2CH(OH)CH2OH)2CH2OCH2CH(OH)CH2OCH2CF2(OCF2CF2) c’ Synthesis of OCF2CH2OCH2CH(OH)CH2OH (Compound 5-2) The perfluoropolyether derivative (compound 5-2), which is an intermediate of Example 5, is used as the compound of Comparative Example 5.

[0150] [Comparative Example 6: CH3OC6H4OCH2CH(OH)CH2OCH2CF2CF2O(CF2CF2CF2O) d’ CF2CF2CH2OCH2CH(OH)CH2CH2CH2CH2CH(OH)CH2OCH2CF2CF2O(CF2CF2CF2O) d’ Synthesis of CF2CF2CH2OCH2CH(OH)CH2OC6H4OCH3 (Compound 6-2) The perfluoropolyether derivative (compound 6-2), which is an intermediate of Example 6, is used as the compound of Comparative Example 6.

[0151] [Oxidative stability evaluation by TG] The oxidation stability of the fluoropolyether compounds obtained in the examples and comparative examples was evaluated using a thermogravimetric analyzer (Hitachi High-Tech Science, STA200). 5 mg of each fluoropolyether compound was placed in a platinum container and heated to 550°C at a heating rate of 2°C / min under a nitrogen atmosphere and an air atmosphere, respectively. The temperature at which the mass of the lubricant decreased by 20% under a nitrogen atmosphere was measured. <1> The temperature at which the mass of the lubricant decreases by 20% in an air atmosphere. <2> , and temperature <1> and temperature <2> The difference is shown in Table 1. [Table 1] Table 1 shows that the fluoropolyether compounds of Examples 1-3 showed no difference in the 20% mass loss temperature in nitrogen and in an oxygen-containing atmosphere. On the other hand, the fluoropolyether compounds of Comparative Examples 1-3 showed a lower 20% mass loss temperature in an oxygen-containing air atmosphere compared to nitrogen. Furthermore, when heating was stopped when the fluoropolyether compounds had lost 20% mass in an air atmosphere, and the compounds remaining in the platinum container were analyzed, compounds with a structure decomposed at the hydrocarbon ether moiety were identified in the comparative examples' fluoropolyether compounds, but no such compounds were identified in the examples. From these results, it was found that the comparative examples' fluoropolyether compounds undergo oxidative decomposition by oxygen in the air, but the fluoropolyether compounds of the examples do not. Therefore, when the fluoropolyether compounds of the examples are used as lubricants, decomposition of the lubricant is unlikely to occur even at high temperatures and in an oxygen-containing atmosphere. This test evaluated the oxidation stability of the fluoropolyether compounds themselves. The stability when applied to magnetic disks will be described later.

[0152] [Evaluation of the stability of a lubricating layer formed on a magnetic disk] The stability of the lubricating layer formed on a magnetic disk using the fluoropolyether compounds obtained in Example 1 and Comparative Example 1 was evaluated. Specifically, the fluoropolyether compounds obtained in Example 1 and Comparative Example 1 were diluted by dissolving them in VETREL XF (manufactured by Mitsui Chemours Fluoroproducts). The diluted lubricants were then applied to the magnetic disks using the dip method to achieve a lubricating layer thickness of 0.7 nm. The thickness of the lubricating layer was measured using FT-IR (Bruker, VERTEX70). The magnetic disks coated with the lubricants were irradiated with ultraviolet light (mixed wavelengths of 254 nm and 185 nm) for an arbitrary amount of time under a nitrogen atmosphere (40 seconds for the lubricant in Example 1, and 20 seconds for the lubricant in Comparative Example 1). Subsequently, the magnetic disks were immersed in a mixed solution of VERTREL-XF and methanol (VERTREL-XF:methanol = 66:33 v / v) for 3 minutes to wash away lubricant molecules not bound to the magnetic disk (rinsing), resulting in magnetic disks with a formed lubricating film. The UV irradiation time was set so that the film thickness of the lubricant after rinsing remained the same. This magnetic disk was heated in an air atmosphere in a 150°C oven (Yamato Scientific Clean Oven DE42), and the film thickness was measured for each heating time to calculate the remaining film thickness. Table 2 shows the heating time and the remaining film thickness of each lubricant film. [Table 2] Table 2 shows that the lubricant of Example 1 exhibited a higher film thickness retention rate even after 60 minutes compared to the lubricant of Comparative Example 1. Furthermore, in the oxidation stability evaluation using TG, the 20% mass loss temperature under an air atmosphere was higher for Comparative Example 1 than for Example 1. This is because the 20% mass loss temperature measured by TG is influenced not only by the oxidation stability of the lubricant but also by its boiling point. However, when the lubricant was applied to a magnetic disk and subjected to ultraviolet treatment, the lubricant molecules on the disk formed a film bonded to the disk surface. Therefore, the lubricating layer of Example 1 demonstrated high oxidation stability and heat resistance on the magnetic disk.

[0153] [Evaluation of the stability of lubricating layers against ultraviolet light] The stability of lubricating layers formed on magnetic disks using the fluoropolyether compounds obtained in Example 1 and Comparative Example 1 as lubricants was evaluated against ultraviolet light. Specifically, the fluoropolyether compounds obtained in Example 1 and Comparative Example 1 were dissolved and diluted in VETREL-XF (manufactured by Mitsui Chemours Fluoroproducts). The diluted lubricants were then applied to magnetic disks using the dip method to a lubricating layer thickness of 8 Å. The thickness of the lubricating layer was measured using FT-IR (Bruker, VERTEX70). The disks coated with the lubricants were irradiated with ultraviolet light (mixed wavelengths of 254 nm and 185 nm) for 20 seconds under a nitrogen atmosphere. Subsequently, the thickness on the disks was measured, and the percentage decrease in thickness after ultraviolet irradiation compared to before irradiation was calculated. The results are shown in Table 3. [Table 3] Table 3 shows that the lubricant of Example 1 showed less film thickness reduction before and after UV irradiation than the lubricant of Comparative Example 1. In other words, the lubricant of Example 1 demonstrated excellent UV resistance. [Industrial applicability]

[0154] A fluoropolyether compound according to one aspect of the present invention can be suitably used as a lubricant for magnetic disks. [Explanation of Symbols]

[0155] 1 Magnetic disk 2 Lubricating layer 3 Protective film layer (protective layer) 4 recording layers 5 Lower layer 6 Soft magnetic underlayer 7 Adhesive layer 8 Non-magnetic substrate

Claims

1. A fluoropolyether compound represented by the following formula (1). 【Chemistry 1】 (In formula (1), Rf is independently a perfluoropolyether group, R １ This refers to a hydrocarbon group having two or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. R ２ and R ３ Each of these is independently a hydrocarbon group having one or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. L １ , L ２ , L ３ , and L ４ Each of these is independently a hydrocarbon group, and each of these hydrocarbon groups may independently contain an OH group and / or an ether bond. R ４ is a hydrogen atom or a hydrocarbon group, and the hydrocarbon group may include an OH group and / or an ether bond. p is an integer between 0 and 1, and q is a real number between 0 and 10. When p = 1, x = 1 and y = 1, or x = 2 and y = 0. In the molecule, the hydrogen atoms bonded to the carbon atoms in the hydrocarbon group may be substituted with fluorine atoms. R １ 、 R ２ 、 R ３ 、 at least one of R4, L1, L2, L3, and L4 contains an ether bond in which at least one carbon atom is substituted by an oxygen atom, and at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bond is substituted by a fluorine atom)

2. R １ This is a hydrocarbon group having 2 to 10 carbon atoms and having two or more OH groups, or a hydrocarbon group having 3 to 25 carbon atoms and having one or more cyclic hydrocarbon groups. R ２ and R ３ Each of these is independently a hydrocarbon group having 1 to 10 carbon atoms and having one or more OH groups, or a hydrocarbon group having 3 to 25 carbon atoms and having one or more cyclic hydrocarbon groups. R １ , R ２ and R ３ The fluoropolyether compound according to claim 1, wherein at least one of the members may include an ether bond in which at least one carbon atom is substituted by an oxygen atom.

3. L １ , L ２ , L ３ , and L ４ This is a hydrocarbon group having 1 to 25 carbon atoms. The fluoropolyether compound according to claim 1, wherein each hydrocarbon group may independently have one or more OH groups and / or contain an ether bond.

4. R １ , R ２ and R ３ The fluoropolyether compound according to claim 1, wherein if at least one of the members contains an ether bond, all hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of at least one of the ether bonds are substituted with fluorine atoms.

5. R １ , R ２ and R ３ The fluoropolyether compound according to claim 1, wherein if at least one of the components contains an ether bond, all hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of all such ether bonds are substituted with fluorine atoms.

6. L １ , L ２ , L ３ , L ４ , and R ４ The fluoropolyether compound according to claim 1, wherein if at least one of the components contains an ether bond, all hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of all such ether bonds are substituted with fluorine atoms.

7. R １ , R ２ , R ３ , R ４ , L １ , L ２ , L ３ , and L ４ The fluoropolyether compound according to claim 1, wherein all hydrogen atoms bonded to carbon atoms other than the carbon atom bonded to the OH group are substituted with fluorine atoms.

8. A fluoropolyether compound represented by the following formula (1). 【Chemistry 2】 (In formula (1), Rf is independently a perfluoropolyether group, R1 is a hydrocarbon group having two or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. R2 and R3 are each independently a hydrocarbon group having one or more OH groups, or a hydrocarbon group having one or more cyclic hydrocarbon groups. L1, L2, L3, and L4 are each independently hydrocarbon groups, and each hydrocarbon group may independently contain an OH group and / or an ether bond. R4 is a hydrogen atom or a hydrocarbon group, and the hydrocarbon group may include an OH group and / or an ether bond. p is an integer between 0 and 1, and q is a real number between 0 and 10. When p = 1, x = 1 and y = 1, or x = 2 and y = 0. In the molecule, the hydrogen atoms bonded to the carbon atoms in the hydrocarbon group may be substituted with fluorine atoms. At least one of R1, R2, and R3 may include an ether bond in which at least one carbon atom is substituted by an oxygen atom, and at least one hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bond is substituted by a fluorine atom. In R1, R2, R3, R4, L1, L2, L3, and L4, all hydrogen atoms bonded to carbon atoms other than those bonded to the OH groups are replaced with fluorine atoms.

9. A lubricant comprising a fluoropolyether compound according to any one of claims 1 to 8.

10. A magnetic disk in which a recording layer, a protective layer, and a lubricating layer are stacked in this order, wherein the lubricating layer contains the lubricant described in claim 9.

11. An esterification step is performed to introduce an ester into the compound represented by the following formula (2), A method for producing a fluoropolyether compound, comprising: a fluorination step of fluorinating the ester obtained in the esterification step; and a reduction step of reducing the fluorinated ester obtained in the fluorination step. 【Transformation 3】 (In formula (2), Rf' is independently a perfluoropolyether group, R １１ , R １２ and R １３ Each of these is an independent hydrocarbon group having one or more OH groups. L １１ , L １２ , L １３ , and L １４ Each of these is independently a hydrocarbon group, and each of these hydrocarbon groups may independently contain an OH group and / or an ether bond. R １４ is a hydrocarbon group or a hydrogen atom, and the hydrocarbon group may have an OH group and / or may contain an ether bond. R １１ , R １２ and R １３ At least one of them includes an ether bond in which at least one carbon atom is substituted by an oxygen atom, p is an integer between 0 and 1, and q is a real number between 0 and 10. When p = 1, x = 1 and y = 1, or x = 2 and y = 0.

Images