WO2022215703A1 - 含フッ素エーテル化合物、磁気記録媒体用潤滑剤および磁気記録媒体 - Google Patents
含フッ素エーテル化合物、磁気記録媒体用潤滑剤および磁気記録媒体 Download PDFInfo
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- 238000004528 spin coating Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 125000000020 sulfo group Chemical group O=S(=O)([*])O[H] 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
- WYURNTSHIVDZCO-UHFFFAOYSA-N tetrahydrofuran Substances C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/04—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers only
- C08G65/22—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring
- C08G65/223—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring containing halogens
- C08G65/226—Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring containing halogens containing fluorine
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C43/00—Ethers; Compounds having groups, groups or groups
- C07C43/02—Ethers
- C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
- C07C43/04—Saturated ethers
- C07C43/13—Saturated ethers containing hydroxy or O-metal groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/002—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from unsaturated compounds
- C08G65/005—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from unsaturated compounds containing halogens
- C08G65/007—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from unsaturated compounds containing halogens containing fluorine
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/32—Polymers modified by chemical after-treatment
- C08G65/329—Polymers modified by chemical after-treatment with organic compounds
- C08G65/331—Polymers modified by chemical after-treatment with organic compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M107/00—Lubricating compositions characterised by the base-material being a macromolecular compound
- C10M107/38—Lubricating compositions characterised by the base-material being a macromolecular compound containing halogen
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/72—Protective coatings, e.g. anti-static or antifriction
- G11B5/725—Protective coatings, e.g. anti-static or antifriction containing a lubricant, e.g. organic compounds
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/72—Protective coatings, e.g. anti-static or antifriction
- G11B5/725—Protective coatings, e.g. anti-static or antifriction containing a lubricant, e.g. organic compounds
- G11B5/7253—Fluorocarbon lubricant
- G11B5/7257—Perfluoropolyether lubricant
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
- C10M2213/06—Perfluoro polymers
- C10M2213/0606—Perfluoro polymers used as base material
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
- C10N2030/12—Inhibition of corrosion, e.g. anti-rust agents or anti-corrosives
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2040/00—Specified use or application for which the lubricating composition is intended
- C10N2040/14—Electric or magnetic purposes
- C10N2040/18—Electric or magnetic purposes in connection with recordings on magnetic tape or disc
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2050/00—Form in which the lubricant is applied to the material being lubricated
- C10N2050/023—Multi-layer lubricant coatings
- C10N2050/025—Multi-layer lubricant coatings in the form of films or sheets
Definitions
- the present invention relates to a fluorine-containing ether compound, a lubricant for magnetic recording media, and a magnetic recording medium.
- a lubricating agent is applied to the surface of the protective layer to form a lubricating layer having a thickness of about 0.5 to 3 nm.
- the lubricating layer improves the durability and protective power of the protective layer and prevents contaminants from entering the magnetic recording medium.
- a burnishing process may be performed to remove projections and particles present on the surface of the magnetic recording medium and improve the smoothness of the surface.
- Lubricants used for forming the lubricating layer of a magnetic recording medium include, for example, those containing a fluorine-based polymer having a repeating structure containing —CF 2 — and having a terminal polar group such as a hydroxyl group.
- Patent Literature 1 discloses a magnetic disk provided with a lubricating layer containing a fluorine-containing ether compound containing three perfluoropolyether chains in the molecule and having the same structure at both ends.
- Patent Literature 2 discloses a magnetic disk provided with a lubricating layer containing a fluorine-containing ether compound containing three perfluoropolyether chains in its molecule and having two different terminal structures.
- Patent Document 3 discloses a magnetic disk having a lubricating layer containing a lubricant containing three perfluoropolyether chains in the molecule and having two hydroxyl groups in the linking groups between the perfluoropolyether chains. ing.
- the magnetic recording/reproducing apparatus it is required to further reduce the flying height of the magnetic head. For this reason, it is desired to further reduce the thickness of the lubricating layer in the magnetic recording medium.
- the corrosion resistance of the magnetic recording medium may become insufficient.
- the tape burnishing process is performed on the surface of the magnetic recording medium after forming the lubricating layer, the corrosion resistance of the magnetic recording medium tends to be insufficient. For this reason, there is a demand for a lubricating layer that is highly effective in suppressing corrosion of magnetic recording media.
- the present invention has been made in view of the above circumstances, and aims to provide a fluorine-containing ether compound suitable as a material for a lubricant for magnetic recording media capable of forming a lubricating layer highly effective in suppressing corrosion of magnetic recording media. aim. Another object of the present invention is to provide a lubricant for magnetic recording media, which contains the fluorine-containing ether compound of the present invention and can form a lubricating layer highly effective in suppressing corrosion of magnetic recording media. Another object of the present invention is to provide a magnetic recording medium provided with a lubricating layer containing the fluorine-containing ether compound of the present invention and having excellent corrosion resistance.
- a first aspect of the present invention provides the following fluorine-containing ether compound.
- a fluorine-containing ether compound represented by the following formula (1) R 1 -CH 2 -R 2 -CH 2 -R 3 -CH 2 -R 4 -CH 2 -R 5 -CH 2 -R 6 -CH 2 -R 7 (1)
- R 3 is a linking group represented by the following formula (2)
- R 5 is the following formula a linking group represented by (3)
- each of R 1 and R 7 independently contains two or three polar groups, each of which is bonded to a different carbon atom; is a terminal group in which the carbon atoms attached to each other are linked via a linking group containing carbon atoms to which no polar group is attached.
- the fluorine-containing ether compound of the first aspect of the present invention preferably has the characteristics described in [2] to [8] below. It is also preferable to arbitrarily combine two or more of the features described in [2] to [8] below.
- [2] The fluorine-containing ether compound according to [1], wherein a in formula (2) is an integer of 2 to 3, and c in formula (3) is an integer of 2 to 3.
- [3] The fluorine-containing ether compound according to [1] or [2], wherein in formula (1), all of the polar groups possessed by R 1 and R 7 are hydroxyl groups.
- —R 1 and —R 7 are each independently a terminal group represented by the following formulas (4-1) to (4-5) [1] to [3] Fluorine-containing ether compound according to any one of.
- a second aspect of the present invention provides the following lubricant for magnetic recording media.
- a lubricant for magnetic recording media comprising the fluorine-containing ether compound according to any one of [1] to [8].
- a third aspect of the present invention provides the following magnetic recording medium. [10] A magnetic recording medium in which at least a magnetic layer, a protective layer, and a lubricating layer are sequentially provided on a substrate, A magnetic recording medium, wherein the lubricating layer contains the fluorine-containing ether compound according to any one of [1] to [8].
- the magnetic recording medium of the third aspect of the present invention preferably has the features described in [11] below. [11] The magnetic recording medium according to [10], wherein the lubricant layer has an average thickness of 0.5 nm to 2.0 nm.
- the fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), it can be used as a material for lubricants for magnetic recording media capable of forming a lubricating layer highly effective in suppressing corrosion of magnetic recording media. Since the lubricant for magnetic recording media of the present invention contains the fluorine-containing ether compound of the present invention, it is possible to form a lubricating layer highly effective in suppressing corrosion of magnetic recording media. Since the magnetic recording medium of the present invention is provided with the lubricating layer containing the fluorine-containing ether compound of the present invention, it has excellent corrosion resistance. Therefore, the magnetic recording medium of the present invention has excellent reliability and durability. Further, since the magnetic recording medium of the present invention is provided with a lubricating layer that is highly effective in suppressing corrosion of the magnetic recording medium, the thickness of the protective layer and/or the lubricating layer can be reduced.
- FIG. 1 is a schematic cross-sectional view showing an example of one embodiment of a magnetic recording medium of the present invention
- one or both of the two linking groups is a methylene chain having 2 or 3 carbon atoms between the central perfluoropolyether chain and the carbon atom to which the hydroxyl group is bonded.
- the lubricating layer containing the fluorine-containing ether compound having the above chain skeleton is formed on the protective layer, both ends of the perfluoropolyether chain arranged at the center of the chain skeleton become the perfluoropolyether chain It adheres to the protective layer due to the hydroxyl group of the linking group placed therebetween. Therefore, the lubricant containing the fluorine-containing ether compound having the chain skeleton has one or two perfluoropolyether chains and has the same number of carbon atoms as the chain skeleton. Compared to the case where a compound is contained, it is easier to wet and spread on the protective layer, can adhere uniformly to the protective layer, and can form a lubricating layer with high coverage and good adhesion.
- both ends of the above-mentioned chain skeleton independently contain two or three polar groups, each polar group is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are , are arranged with terminal groups that are linked through a linking group containing a carbon atom to which no polar group is attached.
- the two or three polar groups possessed by this terminal group can be oriented so as to adhere to the protective layer, unlike the terminal group in which the carbon atoms to which the polar groups are bonded are bonded.
- a lubricating layer having a high coverage and good adhesion is formed.
- the terminal group has a linking group containing a carbon atom to which the polar group is not bonded
- the lubricating layer containing a fluorine-containing ether compound having a terminal group in which the carbon atoms to which the polar group is bonded is bonded.
- the hydrophobicity is better.
- the lubricating layer containing the fluorine-containing ether compound having the specific terminal group bonded to each end of the chain skeleton has appropriate hydrophobicity and good adhesion to the protective layer. is. Therefore, it is presumed that the lubricating layer has a high corrosion-suppressing effect on the magnetic recording medium.
- the inventors of the present invention conducted further investigations, formed a lubricating layer containing the fluorine-containing ether compound on the protective layer, and confirmed that the effect of suppressing corrosion of the magnetic recording medium was high, and arrived at the present invention.
- the fluorine-containing ether compound the lubricant for magnetic recording media (hereinafter sometimes abbreviated as "lubricant")
- the magnetic recording medium of the present invention is described in detail below.
- this invention is not limited only to embodiment shown below.
- the present invention can add, omit, replace, and change the number, amount, position, ratio, material, configuration, etc. within the scope of the present invention.
- the fluorine-containing ether compound of this embodiment is represented by the following formula (1).
- R 3 is a linking group represented by the following formula (2)
- R 5 is the following formula a linking group represented by (3)
- each of R 1 and R 7 independently contains two or three polar groups, each of which is bonded to a different carbon atom; is a terminal group in which the carbon atoms attached to each other are linked through a linking group containing a carbon atom to which no polar group is attached.
- R 1 and R 7 each independently contain two or three polar groups, each polar group is bonded to a different carbon atom, and the polar group is a terminal group in which the carbon atoms that are bonded to each other are bonded via a linking group containing a carbon atom that is not bonded to a polar group.
- each of R 1 and R 7 has two or three polar groups. Therefore, when a lubricant containing this is used to form a lubricating layer on the protective layer, a favorable interaction occurs between the lubricating layer and the protective layer.
- Polar groups include, for example, hydroxyl group (--OH), amino group (--NH 2 ), carboxy group (--COOH), aldehyde group (--COH), carbonyl group (--CO--), sulfo group (--SO 3 H ) and the like.
- R 1 and/or R 7 preferably contain a hydroxyl group as a polar group, and more preferably all polar groups contained in R 1 and R 7 are hydroxyl groups.
- R 1 and/or R 7 is a fluorine-containing ether compound having a hydroxyl group
- a lubricant containing this is used to form a lubricating layer on the protective layer, it is more suitable between the lubricating layer and the protective layer. interaction occurs.
- the total number of polar groups contained in R 1 and polar groups contained in R 7 is 4-6. Since the total number is 4 or more, the lubricating layer containing the fluorine-containing ether compound has high adhesiveness (adhesion) to the protective layer. Further, since the above total number is 6 or less, in a magnetic recording medium having a lubricating layer containing a fluorine-containing ether compound, the polarity of the fluorine-containing ether compound is too high, causing a pick-up that adheres to the magnetic head as foreign matter (smear). can be prevented from occurring.
- the number of polar groups contained in R 1 and the number of polar groups contained in R 7 are preferably the same. That is, it is preferred that R 1 and R 7 each contain two polar groups, or that R 1 and R 7 each contain three polar groups.
- R 1 and R 7 each contain two polar groups, or that R 1 and R 7 each contain three polar groups.
- the lubricant containing the fluorine-containing ether compound adheres to the protective layer in a well-balanced manner, it is easy to obtain a lubricating layer having a high coverage and a high corrosion-inhibiting effect on the magnetic recording medium.
- the polar groups contained in the fluorine-containing ether compound firmly adhere to the protective layer, so that the coverage increases and the corrosion inhibition effect of the magnetic recording medium increases. becomes expensive.
- Each polar group contained in R 1 and R 7 is bonded to a different carbon atom.
- the carbon atoms to which the polar group is bonded are bonded via a linking group containing the carbon atom to which the polar group is not bonded. Therefore, the fluorine-containing ether compound represented by formula (1) has good hydrophobicity compared to, for example, a compound having a terminal group in which the carbon atoms to which the polar groups are bonded are bonded. . From this, it is presumed that the lubricating layer containing the fluorine-containing ether compound represented by formula (1) can prevent water from penetrating and effectively suppress corrosion of the magnetic recording medium.
- the linking group containing the carbon atom to which the polar group is not bonded both the terminal polar group (terminal polar group) and the polar group adjacent to the terminal polar group can be oriented so that they can adhere to the protective layer. From this, when the carbon atoms to which the polar groups are bonded are bonded via a linking group containing carbon atoms to which the polar groups are not bonded, a lubricating layer highly effective in suppressing corrosion of the magnetic recording medium is formed. presumed to be obtained.
- the fluorine-containing ether compound contained in the lubricating layer has a carbon atom bonded to the most terminal polar group (terminal polar group) and a carbon atom bonded to a polar group adjacent to the terminal polar group.
- terminal polar group terminal polar group
- a carbon atom bonded to a polar group adjacent to the terminal polar group a carbon atom bonded to a polar group adjacent to the terminal polar group.
- one of the terminal polar group and the polar group adjacent to the terminal polar group is oriented in the opposite direction with respect to the protective layer. Therefore, one of the terminal polar group and the polar group adjacent to the terminal polar group is less likely to adhere to the protective layer, resulting in poor adhesion between the lubricating layer and the protective layer.
- R 1 and R 7 when the linking group between the carbon atom to which the terminal polar group is bonded and the carbon atom to which the polar group adjacent to the terminal polar group is bonded contains an oxygen atom (for example, the following formula (4- 2), (4-3), and (4-4)), the linking group of R 1 and R 7 has 2 to 5 carbon atoms to which no polar group is bonded. It is preferable to have a linear structure containing Even when the linking group contains an oxygen atom, if it has a linear structure containing two or more carbon atoms to which no polar group is bonded, the fluorine-containing ether compound has good hydrophobicity.
- the linking group has a linear structure containing 5 or less carbon atoms
- the linking group is too hydrophobic to interfere with the adhesion to the protective layer.
- each of R 1 and R 7 has three polar groups
- a lubricating layer having better adhesion to the protective layer can be formed. Therefore, the lubricating layer containing the fluorine-containing ether compound, in which the linking groups of R 1 and R 7 have a linear structure containing the number of carbon atoms within the above range, has excellent adhesion to the protective layer, and Appropriate hydrophobicity makes it possible to prevent the intrusion of water, resulting in a high corrosion-inhibiting effect on the magnetic recording medium.
- the linking group of R 1 and R 7 contains an oxygen atom
- the linking group preferably has a straight chain structure consisting of 3 to 9 atoms, and a straight chain structure consisting of 3 to 6 atoms. It is more preferable to have the structure of
- the number of atoms contained in the linking group is within the above range, the molecular mobility is appropriate and intramolecular aggregation is less likely to occur. Therefore, it becomes a fluorine-containing ether compound capable of forming a lubricating layer having even better adhesion to the protective layer.
- R 1 and R 7 when the linking group between the carbon atom to which the terminal polar group is bonded and the carbon atom to which the polar group adjacent to the terminal polar group is bonded does not contain an oxygen atom (for example, the following formula ( 4-1) and (4-5)), and in any case where R 1 and R 7 have two or three polar groups, the linking group is a polar group It is preferred to have a linear structure containing 1 to 4 unbonded carbon atoms. When the linking group does not contain an oxygen atom and has a linear structure containing one or more carbon atoms to which no polar group is bonded, the resulting fluorine-containing ether compound has good hydrophobicity.
- the linking group when the linking group has a straight chain structure containing 4 or less carbon atoms, the linking group is too hydrophobic to interfere with the adhesion to the protective layer.
- the linking group between the carbon atom to which the terminal polar group is bonded and the carbon atom to which the polar group adjacent to the terminal polar group is bonded does not contain an oxygen atom, the intramolecular interaction is small and intramolecular aggregation is prevented. Hard to happen. Therefore, it becomes a fluorine-containing ether compound capable of forming a lubricating layer having even better adhesion to the protective layer.
- the lubricating layer containing the fluorine-containing ether compound, in which the linking groups of R 1 and R 7 have a linear structure containing the number of carbon atoms within the above range has excellent adhesion to the protective layer.
- water can be prevented from entering, and corrosion of the magnetic recording medium can be highly inhibited.
- R 1 and R 7 may be the same or different, and are preferably the same.
- the fluorine-containing ether compound easily spreads evenly on the protective layer and easily provides a lubricating layer having a uniform film thickness.
- the lubricating layer containing this fluorine-containing ether compound has a good coverage, which is preferable.
- the fluorine-containing ether compound can be efficiently produced in fewer production steps than when R 1 and R 7 are different.
- —R 1 and —R 7 are each independently a terminal group represented by any one of the following formulas (4-1) to (4-5). Preferably.
- —R 1 and —R 7 are terminal groups represented by any of formulas (4-1) to (4-5)
- —R 1 and —R 7 each have two or three hydroxyl groups. Including, the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded has a linear structure containing an appropriate number of carbon atoms. Therefore, when —R 1 and —R 7 are terminal groups represented by formulas (4-1) to (4-5), the fluorine-containing ether compound has appropriate hydrophobicity.
- -R 1 and -R 7 are terminal groups represented by any of the following formulas (4-1), (4-2), (4-4), and (4-5), If it contains two hydroxyl groups, the linking group between the carbon atom to which the hydroxyl group located on the perfluoropolyether chain side is bonded and the carbon atom to which the adjacent hydroxyl group is bonded must also have an appropriate number of carbon atoms. It has a linear structure containing Therefore, the fluorine-containing ether compound has excellent adhesion to the protective layer, has appropriate hydrophobicity, and can form a lubricating layer highly effective in suppressing corrosion of magnetic recording media.
- e is an integer of 0-1 and f is an integer of 1-4.
- the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded does not contain an oxygen atom. Therefore, it exhibits appropriate hydrophobicity.
- f is 4 or less, the hydrophobicity of the linking group is too high to interfere with the adhesion to the protective layer, thereby exhibiting an excellent effect of suppressing corrosion of the magnetic recording medium.
- the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded does not contain an oxygen atom, the intramolecular interaction between the hydroxyl groups contained in the terminal groups is small. . Therefore, intramolecular aggregation is less likely to occur, and a lubricating layer having even better adhesion to the protective layer can be formed. Further, when e is 1, the terminal group represented by formula (4-1) contains three hydroxyl groups, and thus exhibits superior adhesion to the protective layer.
- the fluorine-containing ether compound having a terminal group represented by formula (4-2) has good hydrophobicity and exhibits an excellent anti-corrosion effect on magnetic recording media.
- the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded contains an oxygen atom. Since the terminal group represented by formula (4-2) has h of 1 to 3, it has suitable molecular mobility.
- the intramolecular aggregation of the hydroxyl groups contained in the terminal groups is less likely to occur, and the adhesiveness to the protective layer is further improved.
- the terminal group represented by formula (4-2) contains three hydroxyl groups, and thus exhibits superior adhesion to the protective layer.
- i is an integer of 1-3. Therefore, the fluorine-containing ether compound containing the terminal group represented by formula (4-3) has good hydrophobicity and exhibits an excellent anti-corrosion effect on magnetic recording media.
- the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded contains an oxygen atom.
- the terminal group represented by formula (4-3) has suitable molecular mobility since i is 1 to 3. Therefore, the intramolecular aggregation of the hydroxyl groups contained in the terminal groups is less likely to occur, and the adhesiveness to the protective layer is further improved.
- the fluorine-containing ether compound containing the terminal group represented by formula (4-4) has good hydrophobicity and exhibits an excellent anti-corrosion effect on magnetic recording media. Since the terminal group represented by formula (4-4) contains three hydroxyl groups, it exhibits excellent adhesion to the protective layer.
- the terminal group represented by formula (4-5) is favorable because the linking group between the carbon atom to which the terminal hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded does not contain an oxygen atom. Hydrophobic. Therefore, a lubricating layer containing a fluorine-containing ether compound having a terminal group represented by formula (4-5) exhibits an excellent effect of suppressing corrosion of a magnetic recording medium. In addition, since the terminal group represented by formula (4-5) contains three hydroxyl groups, it exhibits excellent adhesion to the protective layer.
- R 3 is a linking group represented by formula (2) below.
- the linking group represented by formula ( 2 ) is bonded to the methylene group (--CH.sub.2--) in which the rightmost oxygen atom in the parentheses in formula (2) is adjacent to R.sub.4 .
- R5 is a linking group represented by formula ( 3 ) below.
- the linking group represented by formula ( 3 ) is bonded to the leftmost methylene group (--CH.sub.2--) in which the oxygen atom in parentheses in formula (3) is adjacent to R.sub.4 .
- a in formula (2) is an integer of 1-3
- c in formula (3) is an integer of 1-3. It is not possible for a in equation (2) and c in equation (3) to be 1 at the same time. That is, at least one of a and c is an integer of 2-3. Therefore, the fluorine-containing ether compound represented by formula (1) is a compound in which a is 1 in formula (2) representing R 3 and c is 1 in formula (3) representing R 5 The number of carbon atoms contained in the linking group represented by R 3 and/or R 5 is greater than that of R 3 and/or R 5 , resulting in good hydrophobicity.
- a in formula (2) is an integer of 2-3 and c in formula (3) is an integer of 2-3.
- the fluorine-containing ether compound represented by the formula (1) has better hydrophobicity, and the lubricating layer containing it exhibits a more excellent anti-corrosion effect on the magnetic recording medium.
- b in formula (2) is an integer of 1-2
- d in formula (3) is an integer of 1-2.
- the hydroxyl groups in the formulas (2) and (3) improve adhesion to the protective layer in the lubricating layer containing the fluorine-containing ether compound. It is preferable that b in formula (2) and d in formula (3) be 1, since the fluorine-containing ether compound is easy to synthesize.
- R 3 is a linking group represented by formula (2)
- R 5 is a linking group represented by formula (3). Therefore, the oxygen atoms located at both ends of R 3 and R 5 are bonded to the methylene groups (--CH 2 --) located on both sides of R 3 and R 5 respectively to form an ether bond (--O--). Form.
- the four ether bonds formed in this manner impart appropriate flexibility to the fluorine-containing ether compound represented by formula (1), and increase the affinity between the hydroxyl groups of R 3 and R 5 and the protective layer. Increase.
- R 2 , R 4 and R 6 are the same or different perfluoropolyether chains (PFPE chains).
- the PFPE chains represented by R 2 , R 4 and R 6 cover the surface of the protective layer when the lubricant containing the fluorine-containing ether compound of the present embodiment is applied onto the protective layer to form a lubricating layer.
- the lubricating layer is provided with lubricating properties to reduce the frictional force between the magnetic head and the protective layer.
- the PFPE chain imparts water resistance to the lubricating layer containing the fluorine-containing ether compound of the present embodiment due to its low surface energy, and improves the corrosion resistance of the magnetic recording medium provided with the lubricating layer.
- R 2 , R 4 , and R 6 may be PFPE chains, and can be appropriately selected according to the performance required for the lubricant containing the fluorine-containing ether compound.
- PFPE chain include perfluoromethylene oxide polymer, perfluoroethylene oxide polymer, perfluoro-n-propylene oxide polymer, perfluoroisopropylene oxide polymer, copolymers thereof, and the like.
- the PFPE chain may be, for example, a structure represented by the following formula (Rf) derived from a perfluoroalkylene oxide polymer or copolymer.
- Rf formula (Rf) derived from a perfluoroalkylene oxide polymer or copolymer.
- Rf perfluoroalkylene oxide polymer or copolymer.
- w2, w3, w4, and w5 represent an average degree of polymerization, each independently representing 0 to 20; however, w2, w3, w4, and w5 are not all 0 at the same time; w1 and w6 are average values indicating the number of —CF 2 —, each independently representing 1 to
- w1 and w6 are average values indicating the number of —CF 2 — and each independently represents 1 to 3.
- w1 and w6 are determined according to the structure of the repeating unit arranged at the ends of the chain structure in the polymer represented by the formula (Rf).
- (CF 2 O), (CF 2 CF 2 O), (CF 2 CF 2 CF 2 O), and (CF 2 CF 2 CF 2 O) in formula (Rf) are repeating units. There are no particular restrictions on the arrangement order of the repeating units in formula (Rf). Also, the number of types of repeating units in the formula (Rf) is not particularly limited.
- R 2 , R 4 and R 6 in formula (1) are each independently preferably, for example, a PFPE chain represented by formula (Rf-1) below.
- Rf-1 a PFPE chain represented by formula (Rf-1) below.
- w8 and w9 represent an average degree of polymerization, each independently representing 0.1 to 20;
- w7 and w10 are average values representing the number of —CF 2 —, each independently represents 1 to 2.
- Formula (Rf-1) includes any of random copolymers, block copolymers, and alternating copolymers consisting of monomer units (CF 2 CF 2 O) and (CF 2 CF 2 CF 2 O). can be anything.
- w8 and w9 which indicate the average degree of polymerization, each independently represents 0.1 to 20, preferably 0.1 to 15, more preferably 1 to 10.
- w7 and w10 in the formula (Rf-1) are average values indicating the number of —CF 2 — and each independently represents 1 to 2.
- w7 and w10 are determined according to the structure of the repeating unit arranged at the ends of the chain structure in the polymer represented by formula (Rf-1).
- each of R 2 , R 4 and R 6 in formula (1) independently represents one of the following formulas (5) to (9).
- Formula (5) includes any of random copolymers, block copolymers, and alternating copolymers consisting of monomer units (CF 2 —CF 2 —O) and (CF 2 —O).
- k and l represent an average degree of polymerization, each representing 0.1 to 20.
- m indicates an average degree of polymerization and represents 0.1 to 20.
- n indicates an average degree of polymerization and represents 0.1 to 20.
- o indicates an average degree of polymerization and represents 0.1 to 10.
- k and l indicating the average degree of polymerization in formula (5) are each 0.1 to 20, m indicating the average degree of polymerization in formula (6) is 0.1 to 20, and the average degree of polymerization in formula (7) n indicating the degree is 0.1 to 20, o indicating the average degree of polymerization in formula (8) is 0.1 to 10, p indicating the average degree of polymerization in formula (9) is 0.1 to 20 is.
- k, l, m, n, o, and p can be arbitrarily selected within the above ranges.
- the fluorine-containing ether compound When each of k, l, m, n, o, and p is 0.1 or more, the fluorine-containing ether compound provides a lubricating layer capable of further suppressing corrosion of the magnetic recording medium. Further, when k, l, m, n, and p are each 20 or less and o is 10 or less, the viscosity of the fluorine-containing ether compound does not become too high, and the lubricant containing the fluorine-containing ether compound can be easily applied. preferable.
- Each of k, l, m, n, o, and p which indicate the average degree of polymerization, is 1 to 1 because it is a fluorine-containing ether compound that easily spreads on the protective layer and easily provides a lubricating layer having a uniform film thickness. 10 is preferred, and 2-8 is more preferred. Note that k, l, m, n, o, and p may be, for example, 0.5-9, 1-8, 2-7, 3-6, or 4-5.
- R 2 , R 4 and R 6 in formula (1) are any one of formulas (5) to (9), synthesis of the fluorine-containing ether compound is easy, which is preferable.
- R 2 , R 4 and R 6 are any one of formulas (5) to (7), raw materials are easily available, which is more preferable.
- R 2 , R 4 and R 6 are any of formulas (5) to (9), the number of oxygen atoms (ether bond (-O- ) number) ratio is appropriate. Therefore, it becomes a fluorine-containing ether compound having moderate hardness. Therefore, the fluorine-containing ether compound applied on the protective layer is less likely to aggregate on the protective layer, and a thinner lubricating layer can be formed with sufficient coverage.
- the PFPE chains represented by R 2 , R 4 and R 6 may all be the same, may be different, or may be partially the same.
- the phrase "the PFPE chains are the same" includes the case where the structures (repeating units) of the PFPE chains are the same and the average degrees of polymerization are different.
- R 2 and R 6 are the same because synthesis is easy. More preferably, when R2 and R6 are the same , R3 and R5 are the same , and R1 and R7 are the same.
- R 3 and R 5 are the same means that R It means that the atoms contained in 3 and the atoms contained in R 5 are arranged symmetrically. That is, a in formula (2) is the same as c in formula (3), and b in formula (2) is the same as d in formula (3).
- the fluorine-containing ether compound represented by formula (1) is preferably any compound represented by the following formulas (A) to (T).
- ra, qb, sc, tc, rd, qe, qf, sg, tg, rh, qi, sj, tj, qk, rk, sl, tl, rl, qm, rm, qn, rn, qo, ro, qp, sp, tp, qq, sq, tq, sr, tr, rr, qs, ss, ts, st, tt, rt are values indicating the average degree of polymerization , not necessarily an integer.
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 1 and h is 2 in the formula (4-2). and R 2 , R 4 and R 6 are PFPE chains represented by formula (6).
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 2 and h is 2 in the formula (4-2). and R 2 , R 4 and R 6 are PFPE chains represented by formula (7).
- R 1 and R 7 are terminal groups represented by the formula (4-1), e in the formula (4-1) is 0, and f is 1. and R 2 , R 4 and R 6 are PFPE chains represented by formula (5).
- R 1 and R 7 are terminal groups represented by the formula (4-5), and R 2 , R 4 and R 6 are represented by the formula (6) PFPE chains.
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 1 and h is 1 in the formula (4-2). and R 2 , R 4 and R 6 are PFPE chains represented by formula (7).
- R 1 and R 7 are terminal groups represented by the formula (4-3), i in the formula (4-3) is 1, R 2 and R 4 and R6 are PFPE chains represented by formula ( 7 ).
- R 1 and R 7 are terminal groups represented by the formula (4-1), e in the formula (4-1) is 1, and f is 1. and R 2 , R 4 and R 6 are PFPE chains represented by formula (5).
- R 1 and R 7 are terminal groups represented by the formula (4-1), e in the formula (4-1) is 0, and f is 2.
- R 2 , R 4 and R 6 are PFPE chains represented by formula (6).
- R 1 and R 7 are terminal groups represented by the formula (4-4), j in the formula (4-4) is 2, R 2 and R 4 and R6 are PFPE chains represented by formula ( 7 ).
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 2 and h is 1 in the formula (4-2). and R 2 , R 4 and R 6 are PFPE chains represented by formula (5).
- R 1 and R 7 are terminal groups represented by the formula (4-1), e in the formula (4-1) is 1, and f is 1.
- R 2 and R 6 are PFPE chains represented by formula (7), and R 4 is a PFPE chain represented by formula (6).
- R 1 and R 7 are terminal groups represented by the formula (4-4), j in the formula (4-4) is 1, R 2 and R 6 is the PFPE chain represented by formula (5), and R 4 is the PFPE chain represented by formula (6).
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 1 and h is 2 in the formula (4-2). and R 2 and R 6 are PFPE chains represented by formula (7), and R 4 is a PFPE chain represented by formula (6).
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 2 and h is 2 in the formula (4-2).
- R 2 and R 6 are PFPE chains represented by formula (6)
- R 4 is a PFPE chain represented by formula (7).
- the compound represented by the following formula (O) is a PFPE chain in which R 1 and R 7 are terminal groups represented by the formula (4-5) and R 2 and R 6 are represented by the formula (6). and R4 is a PFPE chain represented by formula (7).
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 1 and h is 3 in the formula (4-2). where R 2 and R 6 are PFPE chains represented by formula (5), and R 4 is a PFPE chain represented by formula (7).
- R 1 and R 7 are terminal groups represented by the formula (4-2), g is 1 and h is 1 in the formula (4-2).
- R 2 and R 6 are PFPE chains represented by formula (5), and R 4 is a PFPE chain represented by formula (7).
- R 1 and R 7 are terminal groups represented by the formula (4-2)
- g is 2 and h is 1 in the formula (4-2).
- R 2 and R 6 are PFPE chains represented by formula (6), and R 4 is a PFPE chain represented by formula (5).
- R 1 and R 7 are terminal groups represented by the formula (4-1), e in the formula (4-1) is 0, and f is 3.
- R 2 and R 6 are PFPE chains represented by formula (7)
- R 4 is a PFPE chain represented by formula (5).
- R 1 and R 7 are terminal groups represented by the formula (4-1)
- e is 1 and f is 2 in the formula (4-1).
- R 2 and R 6 are PFPE chains represented by formula (6)
- R 4 is a PFPE chain represented by formula (5).
- Fpa 1 and Fpa 2 in formula (A) are represented by formula (AF).
- ra indicates an average degree of polymerization and ranges from 0.1 to 20. Ra in Fpa 1 and ra in Fpa 2 may be the same or different.
- Fdb 1 and Fdb 2 in formula (B) are represented by formula (BF).
- qb indicates an average degree of polymerization and ranges from 0.1 to 20. qb in Fdb 1 and qb in Fdb2 may be the same or different.
- Ffc 1 and Ffc 2 in the formula (C) are represented by the formula (CF).
- sc and tc in Ffc 1 and Ffc 2 indicate the average degree of polymerization, and represent 0.1 to 20. In Ffc 1 sc and tc in and sc and tc in Ffc 2 may be the same or different.
- Fpd 1 and Fpd 2 in formula (D) are represented by formula (DF).
- rd indicates an average degree of polymerization and ranges from 0.1 to 20. rd in Fpd 1 and rd in Fpd 2 may be the same or different.
- Fde 1 and Fde 2 in formula (E) are represented by formula (EF).
- qe indicates an average degree of polymerization and ranges from 0.1 to 20. qe in Fde 1 and qe in Fde 2 may be the same or different.
- Fdf 1 and Fdf 2 in formula (F) are represented by formula (FF).
- qf indicates an average degree of polymerization and ranges from 0.1 to 20. qf in Fdf 1 and qf in Fdf2 may be the same or different.
- Ffg 1 and Ffg 2 in formula (G) are represented by formula (GF).
- sg and tg in Ffg 1 and Ffg 2 indicate an average degree of polymerization, and represent 0.1 to 20.
- Ffg 1 sg, tg in and sg, tg in Ffg 2 may be the same or different.
- Fph 1 and Fph 2 in formula (H) are represented by formula (HF).
- rh indicates an average degree of polymerization and ranges from 0.1 to 20.
- rh in Fph 1 and rh in Fph2 may be the same or different.
- Fdi 1 and Fdi 2 in formula (I) are represented by formula (IF).
- qi indicates an average degree of polymerization and ranges from 0.1 to 20.
- qi in Fdi 1 and qi in Fdi 2 may be the same or different.
- Ffj 1 and Ffj 2 in the formula (J) are represented by the formula (JF).
- sj and tj in Ffj 1 and Ffj 2 indicate the average degree of polymerization, and represent 0.1 to 20.
- Ffj 1 sj, tj in and sj, tj in Ffj 2 may be the same or different.
- Fdk 1 and Fpk 1 in formula (K) are represented by formula (KF).
- Fdk 1 qk represents an average degree of polymerization and represents 0.1 to 20.
- rk is an average polymerization degree, representing 0.1 to 20.
- Ffl 1 and Fpl 1 in the formula (L) are represented by the formula (LF).
- sl and tl indicate the average degree of polymerization and represent 0.1 to 20.
- rl Indicates the average degree of polymerization and represents 0.1 to 20.
- Fdm 1 and Fpm 1 in the formula (M) are represented by the formula (MF).
- Fdm 1 qm indicates an average degree of polymerization and represents 0.1 to 20.
- Fpm 1 rm is an average polymerization degree, representing 0.1 to 20.
- Fdn 1 and Fpn 1 in the formula (N) are represented by the formula (NF).
- Fdn 1 qn represents an average degree of polymerization and ranges from 0.1 to 20.
- rn is an average polymerization degree, representing 0.1 to 20.
- Fdo 1 and Fpo 1 in the formula (O) are represented by the formula (OF).
- Fdo 1 qo indicates an average degree of polymerization and ranges from 0.1 to 20.
- ro is an average polymerization degree, representing 0.1 to 20.
- Fdp 1 and Ffp 1 in formula (P) are represented by formula (PF).
- Fdp 1 qp indicates an average degree of polymerization and ranges from 0.1 to 20.
- sp and tp are Indicates the average degree of polymerization and represents 0.1 to 20.
- Fdq 1 and Ffq 1 in formula (Q) are represented by formula (QF).
- Fdq 1 qq indicates an average degree of polymerization, and represents 0.1 to 20.
- Ffq 1 sq and tq are Indicates the average degree of polymerization and represents 0.1 to 20.
- Ffr 1 and Fpr 1 in the formula (R) are represented by the formula (RF).
- sr and tr indicate an average degree of polymerization and represent 0.1 to 20.
- rr is Indicates the average degree of polymerization and represents 0.1 to 20.
- Fds 1 and Ffs 1 in formula (S) are represented by formula (SF).
- qs indicates an average degree of polymerization and ranges from 0.1 to 20.
- ss and ts are Indicates the average degree of polymerization and represents 0.1 to 20.
- Fft 1 and Fpt 1 in the formula (T) are represented by the formula (TF).
- st and tt indicate an average degree of polymerization and represent 0.1 to 20.
- rt is Indicates the average degree of polymerization and represents 0.1 to 20.
- the compound represented by the formula (1) is any one of the compounds represented by the above formulas (A) to (T)
- the raw material is easily available, and even if the thickness is thin, the lubrication that can suppress the corrosion of the magnetic recording medium.
- a layer can be formed, which is preferable.
- the compound represented by the formula (1) is any one of the compounds represented by the formulas (B), (D), (F) to (T)
- the corrosion inhibitory effect of the magnetic recording medium is particularly high.
- a lubricating layer can be formed, which is preferable.
- the fluorine-containing ether compound of the present embodiment preferably has a number average molecular weight (Mn) in the range of 500 to 10000, more preferably in the range of 700 to 7000, and in the range of 1000 to 5000. is particularly preferred.
- Mn number average molecular weight
- the lubricant containing the fluorine-containing ether compound of the present embodiment is difficult to evaporate, and the lubricant can be prevented from evaporating and transferring to the magnetic head.
- the number average molecular weight is 10,000 or less, the fluorine-containing ether compound has an appropriate viscosity, and a thin lubricating layer can be easily formed by applying a lubricant containing this.
- a number average molecular weight of 5,000 or less is more preferable because the viscosity becomes easy to handle when applied to a lubricant.
- the number average molecular weight (Mn) of the fluorine-containing ether compound is a value measured by 1 H-NMR and 19 F-NMR using AVANCEIII400 manufactured by Bruker Biospin.
- NMR nuclear magnetic resonance
- the sample was diluted with hexafluorobenzene, d-acetone, d-tetrahydrofuran or the like alone or in a mixed solvent and used for the measurement.
- the hexafluorobenzene peak was -164.7 ppm.
- the acetone peak was set at 2.2 ppm.
- the method for producing the fluorine-containing ether compound of the present embodiment is not particularly limited, and it can be produced using a conventionally known production method.
- the fluorine-containing ether compound of the present embodiment can be produced, for example, using the production method shown below.
- a case of producing a compound having a symmetrical structure centered on R 4 as the fluorine-containing ether compound represented by formula (1) will be described as an example.
- the three PFPE chains represented by R 2 , R 4 and R 6 in formula (1) have the same structure, R 1 and R 7 are the same, and R 3 and R 5 are the same.
- a case of producing a compound will be described as an example.
- a fluorine-based compound is prepared in which hydroxymethyl groups (--CH 2 OH) are arranged at both ends of the perfluoropolyether chain corresponding to R 4 in formula (1).
- This gives intermediate compound 1 having epoxy groups corresponding to R 3 ( R 5 ) at both ends of the perfluoropolyether chain corresponding to R 4 .
- the halogen compound having an epoxy group used in the first reaction includes epichlorohydrin, epibromohydrin, 2-(2-bromoethyl)oxirane, 2-(2-chloroethyl)oxirane, 2-(3-bromopropyl)oxirane, 2-(3-chloropropyl)oxirane and the like.
- the halogen compound having an epoxy group includes, for example, 2-(2-bromoethyl)oxirane, 2-(2-chloroethyl)oxirane, 2-(3-bromopropyl)oxirane, 2-(3-chloropropyl)oxirane and the like can be used.
- the epoxy compound used in the second reaction is, for example, an alcohol having a structure corresponding to R 1 (or R 7 ) of the fluorine-containing ether compound to be produced. , epichlorohydrin, epibromohydrin, 2-bromoethyloxirane, and allyl glycidyl ether.
- an epoxy compound may be synthesized by a method of oxidizing an unsaturated bond, or a commercially available product may be purchased and used.
- the hydroxyl group of the hydroxymethyl group placed at one end of the intermediate compound 2 is reacted with the epoxy groups placed at both ends of the intermediate compound 1 (third reaction).
- the three PFPE chains represented by R 2 , R 4 and R 6 in formula (1) have the same structure, R 1 and R 7 are the same, R 3 and R 5 are the same.
- the order of the first reaction and the second reaction may be reversed.
- R 2 , R 4 and R 6 are the same, R 3 and R 5 are the same, and R 1 and R 7 are different.
- R 2 , R 4 and R 6 are the same, R 1 and R 7 are the same, and R 3 and R 5 are different.
- R 2 , R 4 and R 6 are the same, R 1 and R 7 are the same, and R 3 and R 5 are different.
- a compound it can manufacture using the manufacturing method shown below. That is, in the first reaction described above, a halogen compound having an epoxy group corresponding to R 3 and an epoxy group corresponding to R 5 are added to the hydroxyl group of the hydroxymethyl group arranged at each end of the fluorine-based compound. and the halogen compounds possessed are sequentially reacted. This results in intermediate compound 1a having an epoxy group corresponding to R 3 at one end of the perfluoropolyether chain corresponding to R 4 and an epoxy group corresponding to R 5 at the other end. Thereafter, it can be produced by a method using intermediate compound 1a in place of intermediate compound 1 in the third reaction described above.
- fluorine-containing ether compound represented by formula (1) two compounds represented by R 1 and R 7 are the same, R 3 and R 5 are the same, and R 2 and R 6 are When producing a compound in which the PFPE chain and the PFPE chain represented by R4 are different, it can be produced using the production method shown below. That is, in the first reaction and the second reaction described above, fluorine-based compounds having different types of PFPE chains are used, and other than that, the same method as described above can be used.
- R 1 and R 7 are the same or different, R 3 and R 5 are the same, and R 2 , R 4 and R 6
- R 1 and R 7 are the same or different, R 3 and R 5 are the same, and R 2 , R 4 and R 6
- the PFPE chains shown are to produce different compounds, they can be produced using the production method shown below. That is, in the above-described second reaction, two types of fluorine-based compounds having different types of PFPE chains from the fluorine-based compound used in the first reaction are used as the fluorine-based compounds.
- intermediate compound 2c having a group corresponding to R1 at one end of the perfluoropolyether chain corresponding to R2 and one end of the perfluoropolyether chain corresponding to R6 and intermediate compound 2d having a group corresponding to R 7 are synthesized, respectively.
- ionic contaminants present on the surface of the magnetic recording media. Most of the ionic contaminants adhere from the outside during the manufacturing process of the magnetic recording medium. Ionic contaminants may also be generated when environmental substances that enter a hard disk drive (magnetic recording/reproducing device) adhere to the magnetic recording medium. Specifically, for example, water containing environmental substances such as ions may adhere to the surface of the magnetic recording medium when the magnetic recording medium and/or hard disk drive are held under high temperature and high humidity conditions. When water containing environmental substances such as ions passes through the lubricating layer formed on the surface of the magnetic recording medium, it condenses minute ionic components existing under the lubricating layer to generate ionic contaminants.
- the fluorine-containing ether compound of the present embodiment is a compound represented by formula (1)
- a lubricating layer containing this compound has a high corrosion-inhibiting effect that prevents contaminants from entering the inside of the magnetic recording medium.
- This effect is achieved by the lubricating layer containing the fluorine-containing ether compound of the present embodiment having the following functions ⁇ 1> to ⁇ 5>, so that it has excellent adhesion to the protective layer, has appropriate hydrophobicity, This is obtained by the synergistic effect of being easily formed on the protective layer in a uniform covering state.
- the above lubricating layer comprises one or more hydroxyl groups (--OH) respectively possessed by R 3 and R 5 in the compound represented by formula (1), and two or three each of R 1 and R 7 Due to the polar groups contained, favorable interaction occurs with the protective layer and adhesion to the protective layer occurs. Therefore, the lubricating layer can prevent contaminants from entering the magnetic recording medium and suppress corrosion of the magnetic recording medium.
- the three perfluoropolyether chains (R 2 , R 4 , R 6 ) are arranged between R 1 and R 3 and between R 3 and R 5 and between R5 and R7 , respectively. Therefore, the distance between the polar group of R 1 and the hydroxyl group of R 3 , the distance between the hydroxyl groups of R 3 and R 5 , and the distance between the hydroxyl group of R 5 and the polar group of R 7 are all Appropriate. Therefore, both the hydroxyl groups of R 3 and R 5 and the polar groups of R 1 and R 7 are less likely to be inhibited from bonding with the active sites on the protective layer by adjacent polar groups.
- both the hydroxyl groups of R 3 and R 5 and the polar groups of R 1 and R 7 are likely to participate in bonding with the active sites on the protective layer.
- all the polar groups of the fluorine-containing ether compound are unlikely to be polar groups that do not participate in bonding with the active sites on the protective layer.
- the lubricating layer containing the fluorine-containing ether compound has a reduced number of polar groups that do not participate in bonding with active sites on the protective layer, and exhibits excellent adhesion to the protective layer.
- the distance between the hydroxyl group of R3 and the hydroxyl group of R5 , the distance between the polar group of R1 and the hydroxyl group of R3 , and the distance between the hydroxyl group of R5 and the polar group of R7 are Since all of them are appropriate, the intramolecular interaction between the polar groups of R 3 , R 5 , R 1 and R 7 is small and aggregation is difficult to occur. Therefore, the fluorine-containing ether compound represented by the formula (1) easily wets and spreads on the protective layer, has a uniform coating state, has a high coverage rate, and forms a lubricating layer with good adhesion on the protective layer. can.
- both ends of each perfluoropolyether chain (R 2 , R 4 , R 6 ) are adhered to the protective layer by the polar groups of any one of R 3 , R 5 , R 1 , R 7 . Therefore, the fluorine-containing ether compound coated on the protective layer is unlikely to be bulky. Therefore, the fluorine-containing ether compound represented by the formula (1) easily wets and spreads on the protective layer, has a uniform coating state, has a high coverage rate, and forms a lubricating layer with good adhesion on the protective layer. can.
- the fluorine-containing ether compound represented by formula (1) has three perfluoropolyether chains (R 2 , R 4 , R 6 ). Each perfluoropolyether chain contained in the lubricating layer coats the surface of the protective layer and imparts water resistance to the lubricating layer due to its low surface energy.
- the fluorine-containing ether compound represented by formula (1) contained in the lubricating layer undergoes thermal molecular motion when held under high temperature and high humidity conditions. Water containing environmental substances such as ions is thought to enter through gaps between molecules moving in the lubricating layer.
- the lubricating layer containing the fluorine-containing ether compound represented by the formula (1) has appropriate water resistance and hydrophobicity, water enters the magnetic recording medium through the gaps between the molecules moving in the lubricating layer. and improve the corrosion resistance of magnetic recording media.
- R 3 is a linking group represented by formula (2)
- R 5 is a linking group represented by formula (3)
- a in (2) and c in formula (3) are not 1 at the same time. That is, the fluorine-containing ether compound represented by formula (1) has 2 or 3 carbon atoms between the carbon atom bonded to the hydroxyl group in formula (2) and/or formula (3) and R4 . It has a methylene chain. Therefore, the fluorine-containing ether compound represented by formula (1) has R 3 and/or Alternatively , the number of carbon atoms contained in the linking group represented by R5 is large and the hydrophobicity is good. As a result, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) is difficult for water to pass through and can prevent water from penetrating into the magnetic recording medium.
- the polar groups contained in R 1 and R 7 are respectively bonded to different carbon atoms, and the carbon atoms to which the polar groups are bonded are It is attached through a linking group containing a carbon atom to which no polar group is attached. Therefore, depending on the hydrophobicity of the carbon atoms to which the polar groups contained in R 1 and R 7 are bonded and the carbon atoms contained in the linking groups of R 1 and R 7 , A lubricating layer containing a fluorine ether compound has appropriate hydrophobicity. As a result, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) is difficult for water to pass through, can prevent water from penetrating into the magnetic recording medium, and can suppress corrosion of the magnetic recording medium. becomes.
- the lubricant for magnetic recording media of this embodiment contains a fluorine-containing ether compound represented by formula (1).
- the lubricant of the present embodiment may optionally contain a known material used as a lubricant material within a range that does not impair the characteristics due to the inclusion of the fluorine-containing ether compound represented by formula (1). They can be mixed and used according to need.
- the known material used by mixing with the lubricant of the present embodiment preferably has a number average molecular weight of 1,000 to 10,000.
- the inclusion of the fluorine-containing ether compound represented by formula (1) in the lubricant of the present embodiment is preferably 50% by mass or more, more preferably 70% by mass or more.
- the content of the fluorine-containing ether compound represented by formula (1) may be 80% by mass or more, or may be 90% by mass or more.
- the lubricant of the present embodiment contains the fluorine-containing ether compound represented by formula (1), it is possible to form a lubricating layer highly effective in suppressing corrosion of the magnetic recording medium.
- the lubricating layer made of the lubricant of the present embodiment is highly effective in suppressing corrosion of the magnetic recording medium, and thus can be made thin.
- the magnetic recording medium of this embodiment has at least a magnetic layer, a protective layer and a lubricating layer sequentially provided on a substrate.
- one or more underlayers can be provided between the substrate and the magnetic layer, if necessary.
- An adhesion layer and/or a soft magnetic layer can also be provided between the underlayer and the substrate.
- FIG. 1 is a schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention.
- the magnetic recording medium 10 of the present embodiment includes an adhesive layer 12, a soft magnetic layer 13, a first underlayer 14, a second underlayer 15, a magnetic layer 16, a protective layer 17, and an adhesive layer 12 on a substrate 11.
- a lubricating layer 18 is sequentially provided.
- a non-magnetic substrate or the like can be used in which a film made of NiP or a NiP alloy is formed on a substrate made of a metal such as Al or an Al alloy or an alloy material.
- a non-magnetic substrate made of non-metallic materials such as glass, ceramics, silicon, silicon carbide, carbon, and resin may be used.
- a non-magnetic substrate having a film formed thereon may be used.
- the adhesion layer 12 prevents the progress of corrosion of the substrate 11 that occurs when the substrate 11 and the soft magnetic layer 13 provided on the adhesion layer 12 are arranged in contact with each other.
- the material of the adhesion layer 12 can be appropriately selected from, for example, Cr, Cr alloy, Ti, Ti alloy, CrTi, NiAl, AlRu alloy, and the like.
- the adhesion layer 12 can be formed by, for example, a sputtering method.
- the soft magnetic layer 13 preferably has a structure in which a first soft magnetic film, an intermediate layer made of a Ru film, and a second soft magnetic film are laminated in this order. That is, the soft magnetic layer 13 has a structure in which the soft magnetic films above and below the intermediate layer are antiferro-coupling (AFC) coupled by sandwiching an intermediate layer made of Ru film between two layers of soft magnetic films. It is preferable to have
- Materials for the first soft magnetic film and the second soft magnetic film include CoZrTa alloy and CoFe alloy. Any one of Zr, Ta, and Nb is preferably added to the CoFe alloy used for the first soft magnetic film and the second soft magnetic film. This promotes amorphization of the first soft magnetic film and the second soft magnetic film, improves the orientation of the first underlayer (seed layer), and reduces the flying height of the magnetic head. becomes.
- the soft magnetic layer 13 can be formed by sputtering, for example.
- the first underlayer 14 is a layer that controls the orientation and crystal size of the second underlayer 15 and the magnetic layer 16 provided thereon.
- Examples of the first underlayer 14 include a Cr layer, a Ta layer, a Ru layer, a CrMo alloy layer, a CoW alloy layer, a CrW alloy layer, a CrV alloy layer, and a CrTi alloy layer.
- the first underlayer 14 can be formed by, for example, a sputtering method.
- the second underlayer 15 is a layer for controlling the orientation of the magnetic layer 16 to be good.
- the second underlayer 15 is preferably a layer made of Ru or a Ru alloy.
- the second underlayer 15 may be a layer consisting of one layer, or may be composed of a plurality of layers. When the second underlayer 15 is composed of multiple layers, all layers may be composed of the same material, or at least one layer may be composed of different materials.
- the second underlayer 15 can be formed by, for example, a sputtering method.
- the magnetic layer 16 is composed of a magnetic film having an axis of easy magnetization oriented perpendicularly or horizontally with respect to the substrate surface.
- the magnetic layer 16 is a layer containing Co and Pt, and may be a layer containing oxides, Cr, B, Cu, Ta, Zr, etc. in order to improve the SNR characteristics.
- oxides contained in the magnetic layer 16 include SiO 2 , SiO, Cr 2 O 3 , CoO, Ta 2 O 3 and TiO 2 .
- the magnetic layer 16 may be composed of one layer, or may be composed of a plurality of magnetic layers made of materials with different compositions.
- the first magnetic layer contains Co, Cr, and Pt, and is oxidized. It is preferably a granular structure made of a material containing matter.
- the oxide contained in the first magnetic layer it is preferable to use, for example, oxides of Cr, Si, Ta, Al, Ti, Mg, Co, and the like. Among these, TiO 2 , Cr 2 O 3 , SiO 2 and the like can be particularly preferably used.
- the first magnetic layer is preferably made of a composite oxide to which two or more kinds of oxides are added.
- Cr 2 O 3 —SiO 2 , Cr 2 O 3 —TiO 2 , SiO 2 —TiO 2 and the like can be particularly preferably used.
- the first magnetic layer contains Co, Cr, Pt, oxides, and at least one element selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re. can contain.
- the same material as the first magnetic layer can be used for the second magnetic layer.
- the second magnetic layer preferably has a granular structure.
- the third magnetic layer preferably has a non-granular structure made of a material containing Co, Cr, Pt and no oxide.
- the third magnetic layer contains one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, and Mn. be able to.
- the magnetic layer 16 When the magnetic layer 16 is composed of a plurality of magnetic layers, it is preferable to provide a non-magnetic layer between adjacent magnetic layers. When the magnetic layer 16 is composed of three layers, the first magnetic layer, the second magnetic layer, and the third magnetic layer, the magnetic layer between the first magnetic layer and the second magnetic layer and between the second magnetic layer and the third magnetic layer It is preferable to provide a non-magnetic layer between them.
- Non-magnetic layers provided between adjacent magnetic layers of the magnetic layer 16 are, for example, Ru, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 is Pt, Ta, Zr, Re, Ru, Cu, Nb, Ni, Mn, represents one or more elements selected from Ge, Si, O, N, W, Mo, Ti, V, and B.), etc. can be preferably used.
- Non-magnetic layers provided between adjacent magnetic layers of the magnetic layer 16 preferably use an alloy material containing oxides, metal nitrides, or metal carbides.
- SiO 2 , Al 2 O 3 , Ta 2 O 5 , Cr 2 O 3 , MgO, Y 2 O 3 , TiO 2 and the like can be used as oxides.
- AlN, Si 3 N 4 , TaN, CrN, etc. can be used as metal nitrides, for example.
- TaC, BC, SiC, etc. can be used as metal carbides, for example.
- the non-magnetic layer can be formed, for example, by sputtering.
- the magnetic layer 16 is preferably a magnetic layer for perpendicular magnetic recording in which the axis of easy magnetization is oriented perpendicular to the substrate surface.
- the magnetic layer 16 may be a magnetic layer for longitudinal magnetic recording.
- the magnetic layer 16 may be formed by any conventionally known method such as a vapor deposition method, an ion beam sputtering method, a magnetron sputtering method, or the like.
- the magnetic layer 16 is usually formed by a sputtering method.
- the protective layer 17 protects the magnetic layer 16 .
- the protective layer 17 may be composed of a single layer, or may be composed of a plurality of layers. Examples of materials for the protective layer 17 include carbon, nitrogen-containing carbon, and silicon carbide.
- a carbon-based protective layer can be preferably used, and an amorphous carbon protective layer is particularly preferred. It is preferable that the protective layer 17 is a carbon-based protective layer because the interaction with the hydroxyl groups contained in the fluorine-containing ether compound in the lubricating layer 18 is further increased.
- the adhesion between the carbon-based protective layer and the lubricating layer 18 can be adjusted by using hydrogenated carbon and/or nitrogenated carbon as the carbon-based protective layer and adjusting the hydrogen content and/or nitrogen content in the carbon-based protective layer.
- the hydrogen content in the carbon-based protective layer is preferably 3 to 20 atomic % as measured by hydrogen forward scattering spectroscopy (HFS).
- the nitrogen content in the carbon-based protective layer is preferably 4 to 15 atomic % when measured by X-ray photoelectron spectroscopy (XPS).
- the hydrogen and/or nitrogen contained in the carbon-based protective layer need not be contained uniformly throughout the carbon-based protective layer.
- the carbon-based protective layer is preferably a composition gradient layer in which, for example, the protective layer 17 on the lubricating layer 18 side contains nitrogen and the protective layer 17 on the magnetic layer 16 side contains hydrogen. In this case, the adhesion between the magnetic layer 16 and lubricating layer 18 and the carbon-based protective layer is further improved.
- the film thickness of the protective layer 17 is preferably 1 nm to 7 nm. When the film thickness of the protective layer 17 is 1 nm or more, the performance as the protective layer 17 is sufficiently obtained. It is preferable from the viewpoint of thinning the protective layer 17 that the film thickness of the protective layer 17 is 7 nm or less.
- a sputtering method using a target material containing carbon a sputtering method using a target material containing carbon, a CVD (chemical vapor deposition) method using a hydrocarbon raw material such as ethylene or toluene, an IBD (ion beam deposition) method, or the like may be used.
- a carbon-based protective layer is formed as the protective layer 17, it can be formed by, for example, a DC magnetron sputtering method.
- a plasma CVD method when forming a carbon-based protective layer as the protective layer 17, it is preferable to form an amorphous carbon protective layer by a plasma CVD method.
- the amorphous carbon protective layer formed by the plasma CVD method has a uniform surface and a small roughness.
- Lubricating layer 18 prevents contamination of magnetic recording medium 10 .
- the lubricating layer 18 reduces the frictional force of the magnetic head of the magnetic recording/reproducing device that slides on the magnetic recording medium 10 , thereby improving the durability of the magnetic recording medium 10 .
- the lubricating layer 18 is formed on and in contact with the protective layer 17 as shown in FIG.
- Lubricating layer 18 contains the fluorine-containing ether compound described above.
- the lubricating layer 18 is particularly bonded to the protective layer 17 with high bonding strength when the protective layer 17 arranged under the lubricating layer 18 is a carbon-based protective layer. As a result, even if the thickness of the lubricating layer 18 is small, it becomes easy to obtain the magnetic recording medium 10 in which the surface of the protective layer 17 is coated with a high coverage rate, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented. .
- the average film thickness of the lubricating layer 18 is preferably 0.5 nm (5 ⁇ ) to 2.0 nm (20 ⁇ ), more preferably 0.5 nm (5 ⁇ ) to 1.0 nm (10 ⁇ ).
- the average thickness of the lubricating layer 18 is 0.5 nm or more, the lubricating layer 18 is formed with a uniform thickness without being island-like or network-like. Therefore, the surface of the protective layer 17 can be covered with the lubricating layer 18 at a high coverage rate. Further, by setting the average film thickness of the lubricating layer 18 to 2.0 nm or less, the lubricating layer 18 can be made sufficiently thin, and the flying height of the magnetic head can be made sufficiently small.
- the environmental substances adsorbed to the surface of the magnetic recording medium 10 pass through the gaps in the lubricating layer 18 and reach under the lubricating layer 18. invade.
- Environmental substances that have entered under the lubricating layer 18 are adsorbed and bonded to the protective layer 17 to generate contaminants.
- the generated contaminants (cohesive components) adhere (transfer) to the magnetic head as smear during magnetic recording and reproduction, damaging the magnetic head and degrading the magnetic recording and reproduction characteristics of the magnetic recording and reproducing device. .
- Examples of environmental substances that generate contaminants include siloxane compounds (cyclic siloxane, linear siloxane), ionic impurities, hydrocarbons with relatively high molecular weights such as octacosane, and plasticizers such as dioctyl phthalate.
- Examples of metal ions contained in ionic impurities include sodium ions and potassium ions.
- Examples of inorganic ions contained in ionic impurities include chloride ions, bromide ions, nitrate ions, sulfate ions, and ammonium ions.
- Examples of organic ions contained in ionic impurities include oxalate ions and formate ions.
- Method for Forming a Lubricating Layer As a method of forming the lubricating layer 18, for example, a magnetic recording medium in the middle of production in which each layer up to the protective layer 17 is formed on the substrate 11 is prepared, a lubricating layer forming solution is applied onto the protective layer 17, A drying method may be mentioned.
- the lubricating layer forming solution is obtained by dispersing and dissolving the magnetic recording medium lubricant of the above-described embodiment in a solvent, if necessary, and adjusting the viscosity and concentration suitable for the coating method.
- the solvent used for the lubricating layer forming solution include fluorine-based solvents such as Vertrel (registered trademark) XF (trade name, manufactured by DuPont-Mitsui Fluorochemicals).
- the method of applying the lubricating layer-forming solution is not particularly limited, and examples thereof include a spin coating method, a spray method, a paper coating method, a dipping method, and the like.
- the dipping method for example, the following method can be used. First, the substrate 11 on which the layers up to the protective layer 17 are formed is immersed in a lubricating layer forming solution placed in an immersion tank of a dip coater. Next, the substrate 11 is pulled up from the immersion bath at a predetermined speed. As a result, the lubricating layer forming solution is applied to the surface of the protective layer 17 of the substrate 11 .
- the lubricating layer forming solution can be uniformly applied to the surface of the protective layer 17 , and the lubricating layer 18 can be formed on the protective layer 17 with a uniform film thickness.
- the burnishing process can be, for example, a process of scanning a burnishing tape over the surface of the substrate 11 on which the lubricating layer 18 is formed.
- the varnish tape for example, one made of a resin film holding abrasive grains can be used.
- the grain size of the abrasive grains can be, for example, #6000 to #20000.
- the heat treatment temperature is preferably 100 to 180°C.
- the heat treatment time is preferably 10 to 120 minutes.
- the magnetic recording medium 10 of the present embodiment has at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 successively provided on a substrate 11.
- FIG. In the magnetic recording medium 10 of this embodiment, a lubricating layer 18 containing the fluorine-containing ether compound is formed on and in contact with the protective layer 17 .
- This lubricating layer 18 is highly effective in suppressing corrosion of the magnetic recording medium 10 . Therefore, the magnetic recording medium 10 of the present embodiment has less contaminants on the surface, excellent corrosion resistance, and good reliability and durability.
- the magnetic recording medium 10 of the present embodiment has the lubricating layer 18 having a high corrosion inhibiting effect, the thickness of the protective layer 17 and/or the lubricating layer 18 can be reduced.
- the lubricating layer 18 in the magnetic recording medium 10 of the present embodiment is less likely to generate foreign matter (smear) and can suppress pickup.
- Example 1 The compound represented by the above formula (A) was produced by the method shown below.
- first reaction In a nitrogen gas atmosphere, a compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) r CF 2 CH 2 OH (r indicating the average degree of polymerization in the formula is 2.5) was placed in a 200 mL eggplant flask.
- Numberer average molecular weight 468, molecular weight distribution 1.1 9.4 g (20 mmol), 1.76 g (44 mmol) of 60% sodium hydride, and 15.6 mL of N,N-dimethylformamide were charged and homogenized at room temperature. Stir until it becomes 6.34 g (42 mmol) of 2-(2-bromoethyl)oxirane was added to this homogeneous liquid, and the mixture was stirred at 40° C. for 2 hours to react.
- the compound represented by formula (11) is synthesized by protecting one hydroxyl group of 1,3-propanediol with a THP group (tetrahydropyranyl group) and reacting the other hydroxyl group with epibromohydrin. did.
- the reaction product obtained after the reaction was cooled to 25° C., transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dried over anhydrous sodium sulfate.
- THP represents a tetrahydropyranyl group.
- r indicating the average degree of polymerization is 2.5.
- reaction product obtained after the reaction was cooled to 25° C., transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dried over anhydrous sodium sulfate.
- Example 2 In the first reaction, instead of the compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) r CF 2 CH 2 OH (in the formula, r indicating the average degree of polymerization is 2.5), HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) q CF 2 CF 2 CH 2 OH (in the formula, q indicating the average degree of polymerization is 2.5) (number average molecular weight 693, molecular weight distribution 1.1) was used, and in the second reaction, HOCH 2 CF 2 O (CF 2 CF 2 O) r CF 2 CH 2 OH (r indicating the average degree of polymerization in the formula is 2.5.) instead of the compound represented by HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) q CF 2 CF 2 CH 2 OH (q indicating the average degree of polymerization in the formula is 2.5.) Using 20.8 g of a compound represented by
- a compound represented by formula (13) was synthesized by the following method.
- a TBS group (tert-butyldimethylsilyl group) was introduced to the primary hydroxyl group of 3-allyloxy-1,2-propanediol, and a MOM group (methoxymethyl group) was introduced to the secondary hydroxyl group of the obtained compound.
- the resulting primary hydroxyl group was reacted with 2-(chloropropoxy)tetrahydro-2H-pyran. The double bond of the resulting compound was oxidized.
- a compound represented by formula (13) was obtained.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- the compound represented by formula (14) was synthesized by introducing a THP group (tetrahydropyranyl group) to the primary hydroxyl group of 3-buten-1-ol and oxidizing the double bond of the resulting compound. .
- THP represents a tetrahydropyranyl group.
- Example 4 In the second reaction, the same operation as in Example 1 was performed except that 4.76 g of the compound represented by the following formula (15) was used instead of the compound represented by the formula (11). D) (Fpd 1 and Fpd 2 in formula (D) are represented by formula (DF). rd indicating the average degree of polymerization in Fpd 1 is 2.5, the average degree of polymerization in Fpd 2 is 2.5.) was obtained (molecular weight: 1897, 1.8 mmol).
- a compound represented by formula (15) was synthesized by the following method. 1,2,4-Butanetriol was reacted with benzaldehyde dimethylacetal to synthesize a compound in which the hydroxyl groups bonded to the 2- and 4-position carbons of 1,2,4-butanetriol were protected. A compound represented by the formula (15) was synthesized by reacting this compound with 2-bromoethyloxirane.
- Example 5 In the second reaction, the same operation as in Example 2 was performed except that 3.64 g of the compound represented by the following formula (16) was used instead of the compound represented by the formula (13). E) (Fde 1 and Fde 2 in formula (E) are represented by formula (EF). qe, which indicates the average degree of polymerization in Fde 1 , is 2.5, and the average degree of polymerization in Fde 2 is 2.5.) was obtained (molecular weight: 2456, 1.8 mmol).
- the compound represented by formula (16) was synthesized by oxidizing a compound in which ethylene glycol monoallyl ether was protected using dihydropyran.
- THP represents a tetrahydropyranyl group.
- Example 6 In the second reaction, the same operation as in Example 2 was performed except that 3.89 g of the compound represented by the following formula (17) was used instead of the compound represented by the formula (13).
- F) (Fdf 1 and Fdf 2 in formula (F) are represented by formula (FF).
- qf which indicates the average degree of polymerization in Fdf 1 , is 2.5, and the average degree of polymerization in Fdf 2 is is 2.5.) was obtained (molecular weight: 2484, 1.8 mmol).
- the compound represented by formula (17) was synthesized by oxidizing the double bond of the compound obtained by reacting 3-buten-1-ol and 2-bromoethoxytetrahydropyran.
- THP represents a tetrahydropyranyl group.
- Example 7 In the second reaction, the same operation as in Example 3 was performed except that 4.51 g of the compound represented by the following formula (18) was used instead of the compound represented by the formula (14).
- G) (Ffg 1 and Ffg 2 in formula (G) are represented by formula (GF).
- sg and tg indicating the average degree of polymerization in Ffg 1 are 2.5
- the average in Ffg 2 sg and tg indicating the degree of polymerization are 2.5.) was obtained (molecular weight: 2364, 1.8 mmol).
- a compound represented by formula (18) was synthesized by the following method. 1,2,4-Butanetriol was reacted with benzaldehyde dimethylacetal to synthesize a compound in which the hydroxyl groups bonded to the 2- and 4-position carbons of 1,2,4-butanetriol were protected. A compound represented by the formula (18) was synthesized by reacting this compound with epibromohydrin.
- Example 8 instead of 2-(2-bromoethyl)oxirane in the first reaction, 2-(3-bromopropyl)oxirane was used, and in the second reaction instead of the compound represented by formula (11), the following formula The same operation as in Example 1 was performed except that 3.35 g of the compound represented by (19) was used, and the compound represented by the above formula (H) (Fph 1 and Fph 2 in formula (H)) was is represented by the formula (HF), where rh indicating the average degree of polymerization in Fph 1 is 2.5, and rh indicating the average degree of polymerization in Fph 2 is 2.5. molecular weight 1777, 1.8 mmol).
- the compound represented by formula (19) was synthesized by introducing a THP group (tetrahydropyranyl group) to the primary hydroxyl group of 4-penten-1-ol and oxidizing the double bond of the resulting compound. .
- THP represents a tetrahydropyranyl group.
- Example 9 instead of 2-(2-bromoethyl)oxirane in the first reaction, 2-(3-bromopropyl)oxirane was used, and in the second reaction instead of the compound represented by formula (13), the following formula The same operation as in Example 2 was performed except that 6.99 g of the compound represented by (20) was used, and the compounds represented by the above formula (I) (Fdi 1 and Fdi 2 in formula (I)) were obtained. is represented by the formula (IF), qi indicating the average degree of polymerization in Fdi1 is 2.5 , and qi indicating the average degree of polymerization in Fdi2 is 2.5. , 1.8 mmol).
- a compound represented by formula (20) was synthesized by the following method. Ethylene glycol monoallyl ether was used to oxidize the protected compound using dihydropyran to obtain the first compound. A second compound was obtained by reacting the first compound with the hydroxyl group of 4-penten-1-ol. The double bond of the compound in which the secondary hydroxyl group of the second compound was protected with a THP group was oxidized. Through the above steps, a compound represented by formula (20) was obtained.
- THP represents a tetrahydropyranyl group.
- Example 10 Instead of 2-(2-bromoethyl)oxirane in the first reaction, 2-(3-bromopropyl)oxirane was used, and in the second reaction instead of the compound represented by formula (14), the following formula The same operation as in Example 3 was performed except that 5.77 g of the compound represented by ( 21) was used. (JF), sj and tj indicating the average degree of polymerization in Ffj 1 are 2.5, and sj and tj indicating the average degree of polymerization in Ffj 2 are 2.5). (molecular weight 2452, 1.8 mmol).
- a compound represented by formula (21) was synthesized by the following method.
- a tert-butyldimethylsilyl (TBS) group is introduced as a protecting group to the primary hydroxyl group of 3-allyloxy-1,2-propanediol, and methoxymethyl (MOM) as a protecting group to the secondary hydroxyl group of the resulting compound. group was introduced. Thereafter, the TBS group was removed from the compound, and the resulting primary hydroxyl group was reacted with 2-bromoethoxytetrahydropyran. The double bond of the resulting compound was oxidized. Through the above steps, a compound represented by formula (21) was obtained.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Example 12 In the second reaction, instead of the compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) r CF 2 CH 2 OH (in the formula, r indicating the average degree of polymerization is 2.5), HOCH 2 CF 2 O(CF 2 CF 2 O) s (CF 2 O) t CF 2 CH 2 OH (s and t indicating the average degree of polymerization in the formula are 2.5) (number Except that an average molecular weight of 633 and a molecular weight distribution of 1.1) was used, and 6.02 g of a compound represented by the following formula (22) was used instead of the compound represented by the formula (11).
- a compound represented by formula (22) was synthesized by the following method.
- the ethylene glycol monoallyl ether was protected using dihydropyran, and the resulting compound was oxidized to give the first compound.
- the first compound was reacted with the hydroxyl group of 3-buten-1-ol to obtain a second compound.
- a compound represented by the formula (22) was obtained by protecting the secondary hydroxyl group of the obtained second compound with a MOM group and oxidizing the double bond.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Example 8 The same operation as in Example 8 was performed to obtain a compound represented by the above formula (M) (Fdm 1 and Fpm 1 in formula (M) are represented by formula (MF).
- the average degree of polymerization in Fdm 1 was The indicated qm is 2.5 and the rm indicating the average degree of polymerization in Fpm 1 is 2.5.) was obtained (molecular weight: 2287, 1.8 mmol).
- Example 14 Represented by HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) q CF 2 CF 2 CH 2 OH in the second reaction (q indicating the average degree of polymerization in the formula is 2.5)
- a compound ( number average molecular weight 468, molecular weight distribution 1.1) was used in the same manner as in Example 2, the compound represented by the above formula (N) (Fdn 1 , Fpn 1 in formula (N) is represented by the formula (NF), qn indicating the average degree of polymerization in Fdn 1 is 2.5, and rn indicating the average degree of polymerization in Fpn 1 is 2.5.
- molecular weight 2182, 1.8 mmol molecular weight
- Example 15 In the second reaction, the same operation as in Example 14 was performed except that 4.76 g of the compound represented by the above formula (15) was used instead of the compound represented by the above formula (13).
- the compound represented by (O) (Fdo 1 and Fpo 1 in formula (O) are represented by formula (OF). qo indicating the average degree of polymerization in Fdo 1 is 2.5, and in Fpo 1 is 2.5.) was obtained (molecular weight: 2122, 1.8 mmol).
- Example 16 Represented by HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) q CF 2 CF 2 CH 2 OH in the second reaction (q indicating the average degree of polymerization in the formula is 2.5) Instead of the compound, HOCH 2 CF 2 O(CF 2 CF 2 O) s (CF 2 O) t CF 2 CH 2 OH (where s and t indicate the average degree of polymerization are 2.5).
- the compound represented by formula (23) was synthesized by protecting one hydroxyl group of 1,4-butanediol with a THP group and reacting the other hydroxyl group with epibromohydrin.
- THP represents a tetrahydropyranyl group.
- Example 17 Represented by HOCH 2 CF 2 CF 2 O (CF 2 CF 2 CF 2 O) q CF 2 CF 2 CH 2 OH in the second reaction (q indicating the average degree of polymerization in the formula is 2.5) Instead of the compound, HOCH 2 CF 2 O(CF 2 CF 2 O) s (CF 2 O) t CF 2 CH 2 OH (where s and t indicate the average degree of polymerization are 2.5).
- the compound represented by formula (24) was synthesized by introducing a THP group (tetrahydropyranyl group) to the primary hydroxyl group of 5-hexen-1-ol and oxidizing the double bond of the resulting compound. .
- THP represents a tetrahydropyranyl group.
- the average degree of polymerization in Fft 1 is st and tt are 2.5, and rt, which indicates the average degree of polymerization in Fpt 1 , is 2.5.) was obtained (molecular weight: 2090, 1.8 mmol).
- a compound represented by formula (25) was synthesized by the following method.
- the secondary hydroxyl group of the compound obtained by reacting the compound represented by formula (19) with allyl alcohol was protected with a MOM group.
- a compound represented by the formula (25) was obtained by oxidizing the double bond of the obtained compound.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Fpab 1 and Ffab 1 in formula (AB) are represented by formula (ABF).
- pab indicating the average degree of polymerization in Fpab 1 is 2.5
- mab indicating the average degree of polymerization in Ffab 1
- Each nab represents 2.5.
- Fpac 1 and Ffac 1 in formula (AC) are represented by formula (ACF).
- pac which indicates the average degree of polymerization in Fpac 1
- mac which indicates the average degree of polymerization in Ffac 1
- Each nac represents 2.5.
- Fpad 1 and Ffad 1 in the formula (AD) are represented by the formula (ADF).
- Pad indicating the average degree of polymerization in Fpad 1 is 2.5, mad indicating the average degree of polymerization in Ffad 1 , Each nad represents 2.5.
- Fpae 1 and Ffae 1 in the formula (AE) are represented by the formula (AEF). pae indicating the average degree of polymerization in Fpae 1 is 2.5, mae indicating the average degree of polymerization in Ffae 1 , Each nae represents 2.5.
- the compound represented by formula (26) introduces a THP group as a protecting group to the primary and secondary hydroxyl groups of 3-allyloxy-1,2-propanediol, and oxidizes the double bond of the resulting compound.
- THP represents a tetrahydropyranyl group.
- Fpaf 1 and Ffaf 1 in the formula (AF) are represented by the formula (AFF). paf indicating the average degree of polymerization in Fpaf 1 is 2.5, maf indicating the average degree of polymerization in Ffaf 1 , Each naf represents 2.5.
- Fpag 1 and Ffag 1 in the formula (AG) are represented by the formula (AGF).
- pag which indicates the average degree of polymerization in Fpag 1
- mag which indicates the average degree of polymerization in Ffag 1
- Each nag represents 2.5.
- Fpah 1 and Ffah 1 in the formula (AH) are represented by the formula (AHF). pah indicating the average degree of polymerization in Fpah 1 is 2.5, mah indicating the average degree of polymerization in Ffah 1 , Each nah represents 2.5.)
- Ffal 1 and Ffal 2 in the formula (AL) are represented by the formula (ALF).
- mal and nal indicating the average degree of polymerization in Ffal 1 are 2.5, indicating the average degree of polymerization in Ffal 2 mal and nal represent 2.5.
- Fpam 1 and Fpam 2 in formula (AM) are represented by formula (AMF).
- the pam indicating the average degree of polymerization in Fpam 1 is 2.5, and the pam indicating the average degree of polymerization in Fpam 2 is 2.5.
- a compound represented by the following formula (AN) was synthesized by the following method. In a nitrogen gas atmosphere, a compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) r CF 2 CH 2 OH (in the formula, r indicating the average degree of polymerization is 2.5) was placed in a 200 mL eggplant flask. (Number average molecular weight 468, molecular weight distribution 1.1) 14.0 g, tert-butyl glycidyl ether 2.34 g (molecular weight 130.19, 18 mmol), and t-butanol 28 mL were charged and stirred at room temperature until uniform. did. 1.0 g of potassium tert-butoxide (molecular weight: 112.2, 9 mmol) was further added to this homogeneous liquid, and the mixture was stirred at 70° C. for 16 hours to react.
- the reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dried over anhydrous sodium sulfate. After filtering off the drying agent, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 7.2 g of the compound represented by the following formula (27) (molecular weight: 598, 12.0 mmol).
- reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate.
- the organic layer was washed with water and dried over anhydrous sodium sulfate. After filtering off the drying agent, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 5.9 g of the compound represented by the following formula (29) (molecular weight: 728, 7.7 mmol).
- the reaction product obtained after the reaction was cooled to 25°C, transferred to a separatory funnel containing 100 mL of water, and extracted three times with 100 mL of ethyl acetate. The organic layer was washed with water and dried over anhydrous sodium sulfate. After removing the drying agent by filtration, the filtrate was concentrated and the residue was purified by silica gel column chromatography to obtain 3.3 g (molecular weight: 1812, 2.4 mmol) of the compound represented by the following formula (AN).
- R 1 and R 7 when the compounds of Examples 1 to 20 and Comparative Examples 1 to 14 thus obtained are applied to formula (1) (e and f , g and h in formula (4-2), i in formula (4-3), j in formula (4-4), formula (4-5)), the structure of R 3 and R 5 (formula a and b in (2), c and d in formula (3)), R 2 , R 4 and R 6 structures (k and l in formula (5), m in formula (6), formula Tables 1 and 2 show n) in (7).
- the number average molecular weights (Mn) of the compounds of Examples 1 to 20 and Comparative Examples 1 to 14 were determined by the 1 H-NMR and 19 F-NMR measurements described above. Table 3 shows the results. It should be noted that the average molecular weight of the synthesized compound varies by about 1 to 5 due to the molecular weight distribution of the fluoropolyether used as the raw material of the compound, the difference in the operation when synthesizing the compound, etc. Presumed.
- lubricating layer forming solutions were prepared by the method shown below. Using the lubricating layer forming solution thus obtained, lubricating layers of magnetic recording media were formed by the method described below, and magnetic recording media of Examples 1 to 20 and Comparative Examples 1 to 14 were obtained.
- Magnetic recording medium A magnetic recording medium was prepared by sequentially forming an adhesion layer, a soft magnetic layer, a first underlayer, a second underlayer, a magnetic layer, and a protective layer on a substrate having a diameter of 65 mm.
- the protective layer was made of carbon with a thickness of 1-5 nm.
- the lubricating layer forming solutions of Examples 1 to 20 and Comparative Examples 1 to 14 were applied by dipping onto the protective layer of the magnetic recording medium on which each layer up to the protective layer was formed. The dipping method was performed under conditions of an immersion speed of 10 mm/sec, an immersion time of 30 sec, and a lifting speed of 1.2 mm/sec.
- a varnishing step was performed in which a varnishing tape holding abrasive grains of grain size #6000 was scanned over the surface of the magnetic recording medium on which the lubricating layer was formed. After the burnishing process, the magnetic recording medium was placed in a constant temperature bath at 120° C. and heat-treated for 10 minutes. Magnetic recording media (with varnish) of Examples 1 to 20 and Comparative Examples 1 to 14 were obtained by the above steps. Further, magnetic recording media (without varnish) of Examples 1 to 20 and Comparative Examples 1 to 14 were obtained in the same manner as the magnetic recording media with varnish, except that the varnish process was not performed.
- Evaluation criteria A: Less than 120 B: 120 or more and less than 150 C: 150 or more and less than 350 D: 350 or more and less than 1000 E: 1000 or more
- the magnetic recording media of Examples 1 to 20 having a lubricating layer containing the compound represented by formula (1) were evaluated as A in the corrosion resistance test without tape varnish. With tape varnish, it was A or B, and the corrosion resistance was good. On the other hand, the magnetic recording media of Comparative Examples 1 to 14, with and without tape varnish, had corrosion resistance test results of C to E. In comparison, the corrosion resistance was inferior.
- the lubricating layer was such that R 3 in formula (1) was formula (2) (in formula (2), a is 2 and b is 1).
- R 5 is the formula (3) (where c is 2 and d is 1), or R 3 is the formula (2) (where a is 3 and b is 1).
- R 5 is the formula (3) (where c is 3 and d is 1), and R 1 and R 7 are the terminal represented by formulas (4-1) to (4-5) including compounds that are radicals. Therefore, in the magnetic recording media of Examples 1 to 20, compared with the magnetic recording media of Comparative Examples 1 to 14, the number of carbon atoms contained in R 3 and R 5 of the compound in the lubricating layer is large and the hydrophobic It has good properties.
- the lubricating layer exhibits appropriate hydrophobicity due to the hydrophobicity of the carbon atoms to which the polar groups contained in R1 and R7 are bonded and the carbon atoms contained in the linking groups in R1 and R7 . have. Furthermore, this lubricating layer has good adhesion to the protective layer due to the polar groups of R 3 , R 5 , R 1 and R 7 . From these facts, it is presumed that the magnetic recording media of Examples 1 to 20 prevented entry of water into the lubricating layer from the outside and obtained a good corrosion inhibiting effect.
- the magnetic recording media of Examples 8 to 10, Examples 13, 17, and 20 both with and without varnish had corrosion resistance test results of A, indicating particularly excellent corrosion inhibition. showed an effect.
- the lubricating layers of the magnetic recording media of Examples 8 to 10, Example 13, Example 17, and Example 20 have R 3 represented by formula (2) (in formula (2), a is 3 and b is 1). ) and R 5 includes compounds of formula (3) (c is 3 and d is 1 in formula (3)), so that the number of carbon atoms contained in R 3 and R 5 of the compound is more Many (long methylene chains) are presumed to be due to better hydrophobicity.
- the linking group between the carbon atom to which the terminal polar group is bonded and the carbon atom to which the polar group adjacent to the terminal polar group is bonded does not contain an ether bond (--O--) (4-1), Example 3, Example 4, Example 7, Example 8, Example 11, Example 15, Example 19, Example 20 which are terminal groups represented by (4-5) showed good corrosion inhibition effect.
- the linking groups contained in the terminal groups represented by formulas (4-1) and (4-5) do not contain an ether bond and contain an appropriate number of carbon atoms, so they have good hydrophobicity. It is presumed that this is because it becomes a lubricating layer and prevents the intrusion of water.
- the linking group between the carbon atom to which the terminal polar group is bonded and the carbon atom to which the polar group adjacent to the terminal polar group is bonded is an ether bond in R 1 and R 7 , (4-3), Example 1, Example 2, Example 5, Example 6, Example 9, Example 10, Examples 12 to 14, which are terminal groups represented by (4-4)
- the magnetic recording media of Examples 16-18 exhibited good corrosion inhibition effects. This is because the linking groups contained in the terminal groups represented by formulas (4-2), (4-3), and (4-4) contain an appropriate number of carbon atoms, and thus have good hydrophobicity. It is presumed that this is because it becomes a lubricating layer and prevents the intrusion of water.
- Example 20 both with and without varnish, the corrosion resistance test result was A, showing a particularly excellent corrosion inhibiting effect. This is probably because the three hydroxyl groups respectively contained in R1 and R7 in formula (1) exhibited excellent adhesion to the protective layer. If the adhesion between the lubricating layer and the protective layer is excellent, water can be prevented from entering the lubricating layer from the outside.
- either the terminal hydroxyl group or the hydroxyl group adjacent to the terminal hydroxyl group is oriented in the opposite direction with respect to the protective layer, making it difficult to obtain adhesion of the hydroxyl group to the protective layer. . Also, a lubricating layer containing such a compound cannot obtain sufficient hydrophobicity.
- R 3 in formula (1) is formula (2) (a in formula (2) is 1 and b is 1)
- R 5 is formula (3) (c in formula (3) is Comparative Examples 7 and 13, in which 1 and d are 1) and R 1 is —OH, both had E in the corrosion resistance test result. This is presumed to be due to insufficient hydrophobicity of the lubricating layer and insufficient adhesion of the hydroxyl group of R1 to the protective layer, resulting in a low coverage of the lubricating layer.
- the lubricant for magnetic recording media containing the fluorine-containing ether compound of the present invention it is possible to form a lubricating layer highly effective in suppressing corrosion of magnetic recording media.
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Abstract
Description
本願は、2021年4月8日に、日本に出願された特願2021-065869号に基づき優先権を主張し、その内容をここに援用する。
従来、磁気記録媒体として、基板上に記録層を形成し、記録層上にカーボンなどからなる保護層を形成したものがある。保護層は、記録層に記録された情報を保護するとともに、磁気ヘッドの摺動性を高める。また、保護層は、記録層を被覆して、記録層に含まれる金属が環境物質により腐食されるのを防止する。
また、保護層の表面に潤滑層を形成した後、磁気記録媒体の表面に存在する突起およびパーティクルを除去し、表面の平滑性を向上させるために、バーニッシュ工程を行う場合がある。
例えば、特許文献1には、分子内に3つのパーフルオロポリエーテル鎖を含み、両末端の構造が同一である含フッ素エーテル化合物を含む潤滑層が設けられた磁気ディスクが開示されている。
特許文献2には、分子内に3つのパーフルオロポリエーテル鎖を含み、2つの末端の構造が異なる含フッ素エーテル化合物を含む潤滑層が設けられた磁気ディスクが開示されている。
また、特許文献3には、分子内に3つのパーフルオロポリエーテル鎖を含み、パーフルオロポリエーテル鎖の間の連結基が2つの水酸基を有する潤滑剤を含む潤滑層を有する磁気ディスクが開示されている。
しかし、潤滑層の厚みを薄くすると、磁気記録媒体の耐腐食性が不十分となる場合があった。特に、潤滑層を形成した後の磁気記録媒体の表面に、テープバーニッシュ工程を行った場合、磁気記録媒体の耐腐食性が不十分となりやすかった。このことから、磁気記録媒体の腐食を抑制する効果の高い潤滑層が要求されている。
また、本発明は、本発明の含フッ素エーテル化合物を含み、磁気記録媒体の腐食抑制効果の高い潤滑層を形成できる磁気記録媒体用潤滑剤を提供することを目的とする。
また、本発明は、本発明の含フッ素エーテル化合物を含む潤滑層が設けられ、優れた耐腐食性を有する磁気記録媒体を提供することを目的とする。
本発明の第一の態様は、以下の含フッ素エーテル化合物を提供する。
[1] 下記式(1)で表されることを特徴とする含フッ素エーテル化合物。
R1-CH2-R2-CH2-R3-CH2-R4-CH2-R5-CH2-R6-CH2-R7
(1)
(式(1)中、R2、R4およびR6は、同じまたは異なるパーフルオロポリエーテル鎖である;R3は下記式(2)で表される連結基である;R5は下記式(3)で表される連結基である;R1およびR7はそれぞれ独立に、2つまたは3つの極性基を含み、各極性基がそれぞれ異なる炭素原子に結合し、前記極性基の結合している炭素原子同士が、極性基の結合していない炭素原子を含む連結基を介して結合している末端基である。)
[2] 前記式(2)中のaが2~3の整数であり、前記式(3)中のcが2~3の整数である[1]に記載の含フッ素エーテル化合物。
[3] 前記式(1)において、R1およびR7の有する極性基がすべて水酸基である[1]または[2]に記載の含フッ素エーテル化合物。
(式(4-1)中のeは0~1の整数であり、fは1~4の整数である。)
(式(4-2)中のgは1~2の整数であり、hは1~3の整数である。)
(式(4-3)中のiは1~3の整数である。)
(式(4-4)中のjは1~2の整数である。)
-CF2O-(CF2CF2O)k-(CF2O)l-CF2- (5)
(式(5)中、kおよびlは平均重合度を示し、それぞれ0.1~20を表す。)
-CF2O-(CF2CF2O)m-CF2- (6)
(式(6)中、mは平均重合度を示し、0.1~20を表す。)
-CF2CF2O-(CF2CF2CF2O)n-CF2CF2- (7)
(式(7)中、nは平均重合度を示し、0.1~20を表す。)
-CF2CF2CF2O-(CF2CF2CF2CF2O)o-CF2CF2CF2- (8)
(式(8)中、oは平均重合度を示し、0.1~10を表す。)
-CF(CF3)O-(CF2CF(CF3)O)p-CF(CF3)- (9)
(式(9)中のpは平均重合度を示し、0.1~20を表す。)
[7] 前記式(1)において、R2とR6が同じである[1]~[6]のいずれかに記載の含フッ素エーテル化合物。
[8] 数平均分子量が500~10000の範囲内である[1]~[7]のいずれかに記載の含フッ素エーテル化合物。
[9] [1]~[8]のいずれかに記載の含フッ素エーテル化合物を含むことを特徴とする磁気記録媒体用潤滑剤。
本発明の第三の態様は、以下の磁気記録媒体を提供する。
[10] 基板上に、少なくとも磁性層と、保護層と、潤滑層とが順次設けられた磁気記録媒体であって、
前記潤滑層が、[1]~[8]のいずれかに記載の含フッ素エーテル化合物を含むことを特徴とする磁気記録媒体。
本発明の第三の態様の磁気記録媒体は、以下の[11]に記載される特徴を有することが好ましい。
[11] 前記潤滑層の平均膜厚が、0.5nm~2.0nmである[10]に記載の磁気記録媒体。
本発明の磁気記録媒体用潤滑剤は、本発明の含フッ素エーテル化合物を含むため、磁気記録媒体の腐食抑制効果の高い潤滑層を形成できる。
本発明の磁気記録媒体は、本発明の含フッ素エーテル化合物を含む潤滑層が設けられているため、優れた耐腐食性を有する。このため、本発明の磁気記録媒体は、優れた信頼性および耐久性を有する。また、本発明の磁気記録媒体は、磁気記録媒体の腐食抑制効果の高い潤滑層が設けられているため、保護層および/または潤滑層の厚みを薄くできる。
その結果、メチレン基(-CH2-)とエーテル結合(-O-)とからなる鎖状構造に1以上の水酸基が結合した2つの特定の連結基によって、3つのパーフルオロポリエーテル鎖が結合された鎖状骨格を有し、鎖状骨格の両端にそれぞれメチレン基を介して、2つまたは3つの極性基を含む特定の末端基が結合された含フッ素エーテル化合物とすればよいことを見出した。
本発明者らは、さらに検討を重ね、上記の含フッ素エーテル化合物を含む潤滑層を保護層上に形成し、磁気記録媒体の腐食抑制効果が高いことを確認し、本発明を想到した。
本実施形態の含フッ素エーテル化合物は、下記式(1)で表される。
R1-CH2-R2-CH2-R3-CH2-R4-CH2-R5-CH2-R6-CH2-R7
(1)
(式(1)中、R2、R4およびR6は、同じまたは異なるパーフルオロポリエーテル鎖である;R3は下記式(2)で表される連結基である;R5は下記式(3)で表される連結基である;R1およびR7はそれぞれ独立に、2つまたは3つの極性基を含み、各極性基がそれぞれ異なる炭素原子に結合し、前記極性基の結合している炭素原子同士が、極性基の結合していない炭素原子を含む連結基を介して結合している末端基である。)
上記式(1)で表される含フッ素エーテル化合物において、R1およびR7はそれぞれ独立に、2つまたは3つの極性基を含み、各極性基がそれぞれ異なる炭素原子に結合し、前記極性基の結合している炭素原子同士が、極性基の結合していない炭素原子を含む連結基を介して結合している末端基である。
式(1)で表される含フッ素エーテル化合物では、R1およびR7がそれぞれ2つまたは3つの極性基を有する。このため、これを含む潤滑剤を用いて保護層上に潤滑層を形成した場合に、潤滑層と保護層との間に好適な相互作用が発生する。
また、R1およびR7の有する上記連結基が酸素原子を含む場合、上記連結基は、3~9原子からなる直鎖状の構造を有することが好ましく、3~6原子からなる直鎖状の構造を有することがより好ましい。上記連結基に含まれる原子数が上記範囲内であると、分子の運動性が適切であり、分子内凝集が起こりにくくなる。このため、より一層保護層との密着性に優れる潤滑層を形成できる含フッ素エーテル化合物となる。
(式(4-1)中のeは0~1の整数であり、fは1~4の整数である。)
(式(4-2)中のgは1~2の整数であり、hは1~3の整数である。)
(式(4-3)中のiは1~3の整数である。)
(式(4-4)中のjは1~2の整数である。)
式(1)で表される含フッ素エーテル化合物において、R3は下記式(2)で表される連結基である。式(2)で表される連結基は、式(2)における最も右側の、括弧内の酸素原子がR4に隣接するメチレン基(-CH2-)と結合される。また、式(1)で表される含フッ素エーテル化合物において、R5は下記式(3)で表される連結基である。式(3)で表される連結基は、式(3)における最も左側の、括弧内の酸素原子がR4に隣接するメチレン基(-CH2-)と結合される。
式(1)で表される含フッ素エーテル化合物において、R2、R4、R6は、同じまたは異なるパーフルオロポリエーテル鎖(PFPE鎖)である。R2、R4、R6で示されるPFPE鎖は、本実施形態の含フッ素エーテル化合物を含む潤滑剤を、保護層上に塗布して潤滑層を形成した場合に、保護層の表面を被覆するとともに、潤滑層に潤滑性を付与して磁気ヘッドと保護層との摩擦力を低減させる。また、PFPE鎖は、その低い表面エネルギーによって、本実施形態の含フッ素エーテル化合物を含む潤滑層に耐水性を付与し、潤滑層の設けられた磁気記録媒体の耐腐食性を向上させる。
-(CF2)w1O(CF2O)w2(CF2CF2O)w3(CF2CF2CF2O)w4(CF2CF2CF2CF2O)w5(CF2)w6- (Rf)
(式(Rf)中、w2、w3、w4、w5は平均重合度を示し、それぞれ独立に0~20を表す;ただし、w2、w3、w4、w5のすべてが同時に0になることはない;w1、w6は-CF2-の数を示す平均値であり、それぞれ独立に1~3を表す;式(Rf)における繰り返し単位の配列順序には、特に制限はない。)
式(Rf)中、w2、w3、w4、w5は平均重合度を示し、それぞれ独立に0~20を表し、0~15であることが好ましく、0~10であることがより好ましい。
式(Rf)中、w1、w6は-CF2-の数を示す平均値であり、それぞれ独立に1~3を表す。w1、w6は、式(Rf)で表される重合体において、鎖状構造の端部に配置されている繰り返し単位の構造などに応じて決定される。
式(Rf)における(CF2O)、(CF2CF2O)、(CF2CF2CF2O)、(CF2CF2CF2CF2O)は、繰り返し単位である。式(Rf)における繰り返し単位の配列順序には、特に制限はない。また、式(Rf)における繰り返し単位の種類の数にも、特に制限はない。
-(CF2)w7O-(CF2CF2O)w8-(CF2CF2CF2O)w9-(CF2)w10- (Rf-1)
(式(Rf-1)中、w8、w9は平均重合度を示し、それぞれ独立に0.1~20を表す;w7、w10は-CF2-の数を示す平均値であり、それぞれ独立に1~2を表す。)
式(Rf-1)における繰り返し単位である(CF2CF2O)と(CF2CF2CF2O)との配列順序には、特に制限はない。式(Rf-1)は、モノマー単位(CF2CF2O)と(CF2CF2CF2O)とからなるランダム共重合体、ブロック共重合体、及び、交互共重合体のいずれを含むものであってもよい。式(Rf-1)において、平均重合度を示すw8およびw9は、それぞれ独立に0.1~20を表し、0.1~15であることが好ましく、1~10であることがより好ましい。式(Rf-1)におけるw7およびw10は-CF2-の数を示す平均値であり、それぞれ独立に1~2を表す。w7およびw10は、式(Rf-1)で表される重合体において、鎖状構造の端部に配置されている繰り返し単位の構造などに応じて決定される。
(式(5)中、kおよびlは平均重合度を示し、それぞれ0.1~20を表す。)
-CF2O-(CF2CF2O)m-CF2- (6)
(式(6)中、mは平均重合度を示し、0.1~20を表す。)
-CF2CF2O-(CF2CF2CF2O)n-CF2CF2- (7)
(式(7)中、nは平均重合度を示し、0.1~20を表す。)
-CF2CF2CF2O-(CF2CF2CF2CF2O)o-CF2CF2CF2- (8)
(式(8)中、oは平均重合度を示し、0.1~10を表す。)
-CF(CF3)O-(CF2CF(CF3)O)p-CF(CF3)- (9)
(式(9)中のpは平均重合度を示し、0.1~20を表す。)
また、R2、R4、R6が、式(5)~式(9)のいずれかである場合、パーフルオロポリエーテル鎖中の、炭素原子数に対する酸素原子数(エーテル結合(-O-)数)の割合が、適正である。このため、適度な硬さを有する含フッ素エーテル化合物となる。よって、保護層上に塗布された含フッ素エーテル化合物が、保護層上で凝集しにくく、より一層厚みの薄い潤滑層を十分な被覆率で形成できる。
式(1)で表される含フッ素エーテル化合物においては、合成が容易なものとなるため、R2とR6とが同じであることが好ましい。R2とR6が同じである場合、R3とR5も同じであって、R1とR7も同じであることがより好ましい。このような含フッ素エーテル化合物は、少ない製造工程で容易に効率よく製造できる。なお、本明細書においてR3とR5が同じであるとは、式(1)で表される含フッ素エーテル化合物の中央に配置されたパーフルオロポリエーテル鎖(R4)に対して、R3に含まれる原子とR5に含まれる原子とが対称配置されていることを意味する。すなわち、式(2)中のaが式(3)中のcと同じであり、式(2)中のbが式(3)中のdと同じであることを意味する。
なお、式(A)~(T)中のra、qb、sc、tc、rd、qe、qf、sg、tg、rh、qi、sj、tj、qk、rk、sl、tl、rl、qm、rm、qn、rn、qo、ro、qp、sp、tp、qq、sq、tq、sr、tr、rr、qs、ss、ts、st、tt、rtは、平均重合度を示す値であるため、必ずしも整数とはならない。
下記式(A)~(J)で表される化合物は、いずれもR2とR4とR6が同じである。 下記式(K)~(T)で表される化合物は、いずれもR2とR6が同じである。
下記式(H)~(J)、(M)、(Q)、(T)で表される化合物は、いずれもR3とR5が同じであり、式(2)におけるaが3、bが1であり、式(3)におけるcが3、dが1である。
下記式(B)で表される化合物は、R1とR7が式(4-2)で表される末端基であり、式(4-2)におけるgが2であり、hが2であり、R2とR4とR6が式(7)で表されるPFPE鎖である。
下記式(C)で表される化合物は、R1とR7が式(4-1)で表される末端基であり、式(4-1)におけるeが0であり、fが1であり、R2とR4とR6が式(5)で表されるPFPE鎖である。
下記式(E)で表される化合物は、R1とR7が式(4-2)で表される末端基であり、式(4-2)におけるgが1であり、hが1であり、R2とR4とR6が式(7)で表されるPFPE鎖である。
下記式(F)で表される化合物は、R1とR7が式(4-3)で表される末端基であり、式(4-3)におけるiが1であり、R2とR4とR6が式(7)で表されるPFPE鎖である。
下記式(H)で表される化合物は、R1とR7が式(4-1)で表される末端基であり、式(4-1)におけるeが0であり、fが2であり、R2とR4とR6が式(6)で表されるPFPE鎖である。
下記式(I)で表される化合物は、R1とR7が式(4-4)で表される末端基であり、式(4-4)におけるjが2であり、R2とR4とR6が式(7)で表されるPFPE鎖である。
下記式(K)で表される化合物は、R1とR7が式(4-1)で表される末端基であり、式(4-1)におけるeが1であり、fが1であり、R2とR6が式(7)で表されるPFPE鎖であり、R4が式(6)で表されるPFPE鎖である。
下記式(L)で表される化合物は、R1とR7が式(4-4)で表される末端基であり、式(4-4)におけるjが1であり、R2とR6が式(5)で表されるPFPE鎖であり、R4が式(6)で表されるPFPE鎖である。
下記式(N)で表される化合物は、R1とR7が式(4-2)で表される末端基であり、式(4-2)におけるgが2であり、hが2であり、R2とR6が式(6)で表されるPFPE鎖であり、R4が式(7)で表されるPFPE鎖である。
下記式(O)で表される化合物は、R1とR7が式(4-5)で表される末端基であり、R2とR6が式(6)で表されるPFPE鎖であり、R4が式(7)で表されるPFPE鎖である。
下記式(Q)で表される化合物は、R1とR7が式(4-2)で表される末端基であり、式(4-2)におけるgが1であり、hが1であり、R2とR6が式(5)で表されるPFPE鎖であり、R4が式(7)で表されるPFPE鎖である。
下記式(R)で表される化合物は、R1とR7が式(4-2)で表される末端基であり、式(4-2)におけるgが2であり、hが1であり、R2とR6が式(6)で表されるPFPE鎖であり、R4が式(5)で表されるPFPE鎖である。
下記式(T)で表される化合物は、R1とR7が式(4-1)で表される末端基であり、式(4-1)におけるeが1であり、fが2であり、R2とR6が式(6)で表されるPFPE鎖であり、R4が式(5)で表されるPFPE鎖である。
(式(A)中のFpa1、Fpa2は式(AF)で表される。Fpa1およびFpa2中、raは平均重合度を示し、0.1~20を表す。Fpa1中のraとFpa2中のraは同じであっても異なっていてもよい。)
(式(B)中のFdb1、Fdb2は式(BF)で表される。Fdb1およびFdb2中、qbは平均重合度を示し、0.1~20を表す。Fdb1中のqbとFdb2中のqbは同じであっても異なっていてもよい。)
(式(C)中のFfc1、Ffc2は式(CF)で表される。Ffc1およびFfc2中のsc、tcは平均重合度を示し、0.1~20を表す。Ffc1中のsc、tcとFfc2中のsc、tcは同じであっても異なっていてもよい。)
(式(D)中のFpd1、Fpd2は式(DF)で表される。Fpd1およびFpd2中、rdは平均重合度を示し、0.1~20を表す。Fpd1中のrdとFpd2中のrdは同じであっても異なっていてもよい。)
(式(E)中のFde1、Fde2は式(EF)で表される。Fde1およびFde2中、qeは平均重合度を示し、0.1~20を表す。Fde1中のqeとFde2中のqeは同じであっても異なっていてもよい。)
(式(F)中のFdf1、Fdf2は式(FF)で表される。Fdf1およびFdf2中、qfは平均重合度を示し、0.1~20を表す。Fdf1中のqfとFdf2中のqfは同じであっても異なっていてもよい。)
(式(G)中のFfg1、Ffg2は式(GF)で表される。Ffg1およびFfg2中のsg、tgは平均重合度を示し、0.1~20を表す。Ffg1中のsg、tgとFfg2中のsg、tgは同じであっても異なっていてもよい。)
(式(H)中のFph1、Fph2は式(HF)で表される。Fph1およびFph2中、rhは平均重合度を示し、0.1~20を表す。Fph1中のrhとFph2中のrhは同じであっても異なっていてもよい。)
(式(I)中のFdi1、Fdi2は式(IF)で表される。Fdi1およびFdi2中、qiは平均重合度を示し、0.1~20を表す。Fdi1中のqiとFdi2中のqiは同じであっても異なっていてもよい。)
(式(J)中のFfj1、Ffj2は式(JF)で表される。Ffj1およびFfj2中のsj、tjは平均重合度を示し、0.1~20を表す。Ffj1中のsj、tjとFfj2中のsj、tjは同じであっても異なっていてもよい。)
(式(K)中のFdk1、Fpk1は式(KF)で表される。Fdk1中、qkは平均重合度を示し、0.1~20を表す。Fpk1中、rkは平均重合度を示し、0.1~20を表す。)
(式(L)中のFfl1、Fpl1は式(LF)で表される。Ffl1中、sl、tlは平均重合度を示し、0.1~20を表す。Fpl1中、rlは平均重合度を示し、0.1~20を表す。)
(式(M)中のFdm1、Fpm1は式(MF)で表される。Fdm1中、qmは平均重合度を示し、0.1~20を表す。Fpm1中、rmは平均重合度を示し、0.1~20を表す。)
(式(N)中のFdn1、Fpn1は式(NF)で表される。Fdn1中、qnは平均重合度を示し、0.1~20を表す。Fpn1中、rnは平均重合度を示し、0.1~20を表す。)
(式(O)中のFdo1、Fpo1は式(OF)で表される。Fdo1中、qoは平均重合度を示し、0.1~20を表す。Fpo1中、roは平均重合度を示し、0.1~20を表す。)
(式(P)中のFdp1、Ffp1は式(PF)で表される。Fdp1中、qpは平均重合度を示し、0.1~20を表す。Ffp1中、sp、tpは平均重合度を示し、0.1~20を表す。)
(式(Q)中のFdq1、Ffq1は式(QF)で表される。Fdq1中、qqは平均重合度を示し、0.1~20を表す。Ffq1中、sq、tqは平均重合度を示し、0.1~20を表す。)
(式(R)中のFfr1、Fpr1は式(RF)で表される。Ffr1中、sr、trは平均重合度を示し、0.1~20を表す。Fpr1中、rrは平均重合度を示し、0.1~20を表す。)
(式(S)中のFds1、Ffs1は式(SF)で表される。Fds1中、qsは平均重合度を示し、0.1~20を表す。Ffs1中、ss、tsは平均重合度を示し、0.1~20を表す。)
(式(T)中のFft1、Fpt1は式(TF)で表される。Fft1中、st、ttは平均重合度を示し、0.1~20を表す。Fpt1中、rtは平均重合度を示し、0.1~20を表す。)
式(1)で表される化合物が、式(B)、(D)、(F)~(T)で表される化合物のいずれかであると、特に、磁気記録媒体の腐食抑制効果の高い潤滑層を形成でき、好ましい。
本実施形態の含フッ素エーテル化合物の製造方法は、特に限定されるものではなく、従来公知の製造方法を用いて製造できる。本実施形態の含フッ素エーテル化合物は、例えば、以下に示す製造方法を用いて製造できる。
本実施形態においては、式(1)で表される含フッ素エーテル化合物として、R4を中心とする対称構造を有する化合物を製造する場合を例に挙げて説明する。具体的には、式(1)におけるR2、R4、R6で示される3つのPFPE鎖が同じ構造を有し、R1とR7とが同じで、R3とR5とが同じである化合物を製造する場合を例に挙げて説明する。
R1(=R7)に対応する基を有するエポキシ化合物は、水酸基を適切な保護基を用いて保護してから、上記フッ素系化合物と反応させても良い。
以上の工程を行うことにより、式(1)においてR2、R4、R6で示される3つのPFPE鎖が同じ構造を有し、R1とR7とが同じで、R3とR5とが同じである化合物を製造できる。ここで、第一反応と第二反応の順は逆であっても良い。
すなわち、上述した第二反応において、R1に対応する基を有する中間体化合物2aと、R7に対応する基を有する中間体化合物2bとをそれぞれ合成する。その後、上述した第三反応において、中間体化合物1の各末端に配置されたR3(=R5)に対応するエポキシ基に対して、中間体化合物2aと中間体化合物2bとを順次反応させる方法により製造できる。
すなわち、上述した第一反応において、前記フッ素系化合物の各末端に配置されたヒドロキシメチル基の水酸基に対して、R3に対応するエポキシ基を有するハロゲン化合物と、R5に対応するエポキシ基を有するハロゲン化合物とを順次反応させる。このことにより、R4に対応するパーフルオロポリエーテル鎖の一端に、R3に対応するエポキシ基を有し、他端にR5に対応するエポキシ基を有する中間体化合物1aが得られる。その後、上述した第三反応において、中間体化合物1に代えて中間体化合物1aを用いる方法により製造できる。
すなわち、上述した第一反応と第二反応とにおいて、種類の異なるPFPE鎖を有するフッ素系化合物を使用し、それ以外は、上記と同じ方法により製造できる。
すなわち、上述した第二反応において、フッ素系化合物として、第一反応で使用したフッ素系化合物とPFPE鎖の種類が異なる2種類のものを用いる。そして、第二反応において、R2に対応するパーフルオロポリエーテル鎖の一方の末端にR1に対応する基を有する中間体化合物2cと、R6に対応するパーフルオロポリエーテル鎖の一方の末端にR7に対応する基を有する中間体化合物2dとを、それぞれ合成する。その後、上述した第三反応において、中間体化合物1の各末端に配置されたR3(=R5)に対応するエポキシ基に対して、中間体化合物2cと中間体化合物2dとを順次反応させる方法により製造できる。
磁気記録媒体の腐食の原因としては、磁気記録媒体の表面に存在するイオン性の汚染物質が挙げられる。イオン性の汚染物質の多くは、磁気記録媒体の製造工程において外部から付着する。イオン性の汚染物質は、ハードディスクドライブ(磁気記録再生装置)内に侵入した環境物質が、磁気記録媒体に付着して生成されることもある。具体的には、例えば、磁気記録媒体および/またはハードディスクドライブが高温・高湿条件下で保持されることにより、イオンなどの環境物質を含む水が磁気記録媒体の表面に付着する場合がある。イオンなどの環境物質を含む水は、磁気記録媒体の表面に形成された潤滑層を通り抜けると、潤滑層の下に存在する微少のイオン成分を凝縮させて、イオン性の汚染物質を生成させる。
このため、R1の有する極性基とR3の有する水酸基との距離、R3とR5の有する水酸基同士の距離、R5の有する水酸基とR7の有する極性基との距離が、いずれも適正である。したがって、R3およびR5の有する水酸基も、R1およびR7の有する極性基も、保護層上の活性点との結合を、隣接する極性基によって阻害されにくい。よって、R3およびR5の有する水酸基、およびR1およびR7の有する極性基は、いずれも保護層上の活性点との結合に関与しやすい。言い換えると、上記含フッ素エーテル化合物の有する極性基は、全て保護層上の活性点との結合に関与しない極性基になりにくい。その結果、上記含フッ素エーテル化合物を含む潤滑層は、保護層上の活性点との結合に関与しない極性基の数が抑制され、保護層との密着性に優れる。
潤滑層に含まれる式(1)で表される含フッ素エーテル化合物は、高温・高湿条件下で保持されると、熱による分子運動を起こす。イオンなどの環境物質を含む水は、潤滑層中で分子運動する分子間の隙間から侵入すると考えられる。
式(1)で表される含フッ素エーテル化合物を含む潤滑層は、適切な耐水性および疎水性を有するため、潤滑層中で分子運動する分子間の隙間から磁気記録媒体内部への水の侵入を妨げ、磁気記録媒体の耐腐食性を向上させる。
本実施形態の磁気記録媒体用潤滑剤は、式(1)で表される含フッ素エーテル化合物を含む。
本実施形態の潤滑剤は、式(1)で表される含フッ素エーテル化合物を含むことによる特性を損なわない範囲内であれば、潤滑剤の材料として使用されている公知の材料を、必要に応じて混合して用いることができる。
本実施形態の磁気記録媒体は、基板上に、少なくとも磁性層と保護層と潤滑層が順次設けられたものである。
本実施形態の磁気記録媒体では、基板と磁性層との間に、必要に応じて1層または2層以上の下地層を設けることができる。また、下地層と基板との間に付着層および/または軟磁性層を設けることもできる。
本実施形態の磁気記録媒体10は、基板11上に、付着層12と、軟磁性層13と、第1下地層14と、第2下地層15と、磁性層16と、保護層17と、潤滑層18とが順次設けられた構造をなしている。
基板11としては、例えば、AlもしくはAl合金などの金属または合金材料からなる基体上に、NiPまたはNiP合金からなる膜が形成された非磁性基板等を用いることができる。
また、基板11としては、ガラス、セラミックス、シリコン、シリコンカーバイド、カーボン、樹脂などの非金属材料からなる非磁性基板を用いてもよいし、これらの非金属材料からなる基体上にNiPまたはNiP合金の膜を形成した非磁性基板を用いてもよい。
付着層12は、基板11と、付着層12上に設けられる軟磁性層13とを接して配置した場合に生じる、基板11の腐食の進行を防止する。
付着層12の材料は、例えば、Cr、Cr合金、Ti、Ti合金、CrTi、NiAl、AlRu合金等から適宜選択できる。付着層12は、例えば、スパッタリング法により形成できる。
軟磁性層13は、第1軟磁性膜と、Ru膜からなる中間層と、第2軟磁性膜とが順に積層された構造を有していることが好ましい。すなわち、軟磁性層13は、2層の軟磁性膜の間にRu膜からなる中間層を挟み込むことによって、中間層の上下の軟磁性膜がアンチ・フェロ・カップリング(AFC)結合した構造を有していることが好ましい。
第1軟磁性膜および第2軟磁性膜に使用されるCoFe合金には、Zr、Ta、Nbの何れかを添加することが好ましい。これにより、第1軟磁性膜および第2軟磁性膜の非晶質化が促進され、第1下地層(シード層)の配向性が向上するとともに、磁気ヘッドの浮上量を低減することが可能となる。
軟磁性層13は、例えば、スパッタリング法により形成できる。
第1下地層14は、その上に設けられる第2下地層15および磁性層16の配向および結晶サイズを制御する層である。
第1下地層14としては、例えば、Cr層、Ta層、Ru層、あるいはCrMo合金層、CoW合金層、CrW合金層、CrV合金層、CrTi合金層などが挙げられる。
第1下地層14は、例えば、スパッタリング法により形成できる。
第2下地層15は、磁性層16の配向が良好になるように制御する層である。第2下地層15は、RuまたはRu合金からなる層であることが好ましい。
第2下地層15は、1層からなる層であってもよいし、複数層から構成されていてもよい。第2下地層15が複数層からなる場合、全ての層が同じ材料から構成されていてもよいし、少なくとも一層が異なる材料から構成されていてもよい。
第2下地層15は、例えば、スパッタリング法により形成できる。
磁性層16は、磁化容易軸が基板面に対して垂直または水平方向を向いた磁性膜からなる。磁性層16は、CoとPtを含む層であり、さらにSNR特性を改善するために、酸化物や、Cr、B、Cu、Ta、Zr等を含む層であってもよい。
磁性層16に含有される酸化物としては、SiO2、SiO、Cr2O3、CoO、Ta2O3、TiO2等が挙げられる。
例えば、磁性層16が、下から順に積層された第1磁性層と第2磁性層と第3磁性層の3層からなる場合、第1磁性層は、Co、Cr、Ptを含み、さらに酸化物を含んだ材料からなるグラニュラー構造であることが好ましい。第1磁性層に含有される酸化物としては、例えば、Cr、Si、Ta、Al、Ti、Mg、Co等の酸化物を用いることが好ましい。その中でも、特に、TiO2、Cr2O3、SiO2等を好適に用いることができる。また、第1磁性層は、酸化物を2種類以上添加した複合酸化物からなることが好ましい。その中でも、特に、Cr2O3-SiO2、Cr2O3-TiO2、SiO2-TiO2等を好適に用いることができる。
第2磁性層には、第1磁性層と同様の材料を用いることができる。第2磁性層は、グラニュラー構造であることが好ましい。
非磁性層は、例えば、スパッタリング法により形成できる。
磁性層16は、蒸着法、イオンビームスパッタ法、マグネトロンスパッタ法等、従来公知のいかなる方法によって形成してもよい。磁性層16は、通常、スパッタリング法により形成される。
保護層17は、磁性層16を保護する。保護層17は、一層から構成されていてもよいし、複数層から構成されていてもよい。保護層17の材料としては、炭素、窒素を含む炭素、炭化ケイ素などが挙げられる。
保護層17としては、炭素系保護層を好ましく用いることができ、特にアモルファス炭素保護層が好ましい。保護層17が炭素系保護層であると、潤滑層18中の含フッ素エーテル化合物に含まれる水酸基との相互作用が一層高まるため、好ましい。
保護層17として炭素系保護層を形成する場合、例えばDCマグネトロンスパッタリング法により成膜できる。特に、保護層17として炭素系保護層を形成する場合、プラズマCVD法により、アモルファス炭素保護層を成膜することが好ましい。プラズマCVD法により成膜したアモルファス炭素保護層は、表面が均一で、粗さが小さいものとなる。
潤滑層18は、磁気記録媒体10の汚染を防止する。また、潤滑層18は、磁気記録媒体10上を摺動する磁気記録再生装置の磁気ヘッドの摩擦力を低減させて、磁気記録媒体10の耐久性を向上させる。
潤滑層18は、図1に示すように、保護層17上に接して形成されている。潤滑層18は、上述の含フッ素エーテル化合物を含む。
潤滑層18を形成する方法としては、例えば、基板11上に保護層17までの各層が形成された製造途中の磁気記録媒体を用意し、保護層17上に潤滑層形成用溶液を塗布し、乾燥させる方法が挙げられる。
潤滑層形成用溶液に用いられる溶媒としては、例えば、バートレル(登録商標)XF(商品名、三井デュポンフロロケミカル社製)等のフッ素系溶媒等が挙げられる。
ディップ法を用いる場合、例えば、以下に示す方法を用いることができる。まず、ディップコート装置の浸漬槽に入れられた潤滑層形成用溶液中に、保護層17までの各層が形成された基板11を浸漬する。次いで、浸漬槽から基板11を所定の速度で引き上げる。このことにより、潤滑層形成用溶液を基板11の保護層17上の表面に塗布する。
ディップ法を用いることで、潤滑層形成用溶液を保護層17の表面に均一に塗布することができ、保護層17上に均一な膜厚で潤滑層18を形成できる。
バーニッシュ工程は、例えば、潤滑層18を形成した基板11の表面上に、バーニッシュテープを走査する工程とすることができる。バーニッシュテープとしては、例えば、砥粒を保持させた樹脂フィルムからなるものを用いることができる。砥粒の粒度は、例えば、#6000~#20000とすることができる。
熱処理温度は100~180℃とすることが好ましい。熱処理温度が100℃以上であると、潤滑層18と保護層17との密着性を向上させる効果が十分に得られる。また、熱処理温度を180℃以下にすることで、潤滑層18の熱分解を防止できる。熱処理時間は10~120分とすることが好ましい。
以下に示す方法により、上記式(A)で示される化合物を製造した。
(第一反応)
窒素ガス雰囲気下、200mLナスフラスコにHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物(数平均分子量468、分子量分布1.1)9.4g(20mmol)と、60%水素化ナトリウム1.76g(44mmol)と、N,N-ジメチルホルムアミド15.6mLとを仕込み、室温で均一になるまで撹拌した。この均一の液に2-(2-ブロモエチル)オキシラン6.34g(42mmol)を加え、40℃で2時間撹拌して反応させた。
窒素ガス雰囲気下、200mLナスフラスコにHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物(数平均分子量468、分子量分布1.1)14.0gと、下記式(11)で表される化合物3.89g(分子量216.28、18mmol)と、t-ブタノール28mLとを仕込み、室温で均一になるまで撹拌した。この均一の液にさらにカリウムtert-ブトキシド1.0g(分子量112.2、9mmol)を加え、70℃で16時間撹拌して反応させた。
反応後に得られた反応生成物を25℃に冷却し、水100mLが入った分液漏斗へ移し、酢酸エチル100mLで3回抽出した。有機層を水洗し、無水硫酸ナトリウムによって脱水した。乾燥剤を濾別した後、濾液を濃縮し、残渣をシリカゲルカラムクロマトグラフィーにて精製し、中間体化合物2として下記式(12)で示される化合物8.2g(分子量684、12.0mmol)を得た。
窒素ガス雰囲気下、200mLナスフラスコに式(12)で表される中間体化合物2(式中の平均重合度を示すrは2.5である。)6.8gと、カリウムtert-ブトキシド0.34gと、t-ブタノール9.4mLとを仕込み、室温で均一になるまで撹拌した。この均一の液にさらに式(10)で表される中間体化合物1(式中の平均重合度を示すrは2.5である。)1.8gを加え、70℃で16時間撹拌して反応させた。
1H-NMR(CD3COCD3):δ[ppm]=1.38~1.75(8H)、3.37~4.31(46H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
第一反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物(数平均分子量693、分子量分布1.1)を13.9g用いたことと、第二反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物(数平均分子量693、分子量分布1.1)を20.8g用いたことと、式(11)で表される化合物の代わりに、下記式(13)で表される化合物を6.02g用いたこと以外は、実施例1と同様な操作を行い、上記式(B)で表される化合物(式(B)におけるFdb1、Fdb2は式(BF)で表される。Fdb1中の平均重合度を示すqbは2.5、Fdb2中の平均重合度を示すqbは2.5である。)を4.7g(分子量2632、1.8mmol)得た。
3-アリルオキシ-1,2-プロパンジオールの1級水酸基にTBS基(tert-ブチルジメチルシリル基)を導入し、得られた化合物の2級水酸基にMOM基(メトキシメチル基)を導入した。得られた化合物のTBS基を除去した後、生じた1級水酸基に2-(クロロプロポキシ)テトラヒドロ-2H-ピランを反応させた。得られた化合物の二重結合を酸化した。以上の工程により、式(13)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.37~1.81(8H)、3.36~4.35(58H)
19F-NMR(acetone-D6):δ[ppm]=-84.0~-83.0(30F)、-86.4(12F)、-124.3(12F)、-130.0~-129.0(15F)
第一反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物(数平均分子量633、分子量分布1.1)を12.7g用いたことと、第二反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物(数平均分子量633、分子量分布1.1)を19.0g用いたことと、式(11)で表される化合物の代わりに、下記式(14)で表される化合物を3.10g用いたこと以外は、実施例1と同様な操作を行い、上記式(C)で表される化合物(式(C)におけるFfc1、Ffc2は式(CF)で表される。Ffc1中の平均重合度を示すsc、tcは2.5、Ffc2中の平均重合度を示すsc、tcは2.5である。)を4.0g(分子量2216、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.67(8H)、3.39~4.34(38H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(15F)、-77.7(6F)、-80.3(6F)、-91.0~-88.5(30F)
第二反応において式(11)で表される化合物の代わりに、下記式(15)で表される化合物を4.76g用いたこと以外は、実施例1と同様な操作を行い、上記式(D)で表される化合物(式(D)におけるFpd1、Fpd2は式(DF)で表される。Fpd1中の平均重合度を示すrdは2.5、Fpd2中の平均重合度を示すrdは2.5である。)を3.4g(分子量1897、1.8mmol)得た。
1,2,4-ブタントリオールにベンズアルデヒドジメチルアセタールを反応させて、1,2,4-ブタントリオールの2位の炭素と4位の炭素に結合した水酸基を保護した化合物を合成した。この化合物と2-ブロモエチルオキシランとを反応させることで、式(15)で表される化合物を合成した。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.65(12H)、3.42~4.35(50H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
第二反応において式(13)で表される化合物の代わりに、下記式(16)で表される化合物を3.64g用いたこと以外は、実施例2と同様な操作を行い、上記式(E)で表される化合物(式(E)におけるFde1、Fde2は式(EF)で表される。Fde1中の平均重合度を示すqeは2.5、Fde2中の平均重合度を示すqeは2.5である。)を4.4g(分子量2456、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.37~1.64(4H)、3.42~4.35(46H)
19F-NMR(acetone-D6):δ[ppm]=-84.0~-83.0(30F)、-86.4(12F)、-124.3(12F)、-130.0~-129.0(15F)
第二反応において式(13)で表される化合物の代わりに、下記式(17)で表される化合物を3.89g用いたこと以外は、実施例2と同様な操作を行い、上記式(F)で表される化合物(式(F)におけるFdf1、Fdf2は式(FF)で表される。Fdf1中の平均重合度を示すqfは2.5、Fdf2中の平均重合度を示すqfは2.5である。)を4.5g(分子量2484、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.59(8H)、3.37~4.38(46H)
19F-NMR(acetone-D6):δ[ppm]=-84.0~-83.0(30F)、-86.4(12F)、-124.3(12F)、-130.0~-129.0(15F)
第二反応において式(14)で表される化合物の代わりに、下記式(18)で表される化合物を4.51g用いたこと以外は、実施例3と同様な操作を行い、上記式(G)で表される化合物(式(G)におけるFfg1、Ffg2は式(GF)で表される。Ffg1中の平均重合度を示すsg、tgは2.5、Ffg2中の平均重合度を示すsg、tgは2.5である。)を4.3g(分子量2364、1.8mmol)得た。
1,2,4-ブタントリオールにベンズアルデヒドジメチルアセタールを反応させて、1,2,4-ブタントリオールの2位の炭素と4位の炭素に結合した水酸基を保護した化合物を合成した。この化合物とエピブロモヒドリンとを反応させることにより、式(18)で表される化合物を合成した。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.67(8H)、3.38~4.33(50H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(15F)、-77.7(6F)、-80.3(6F)、-91.0~-88.5(30F)
第一反応において2-(2-ブロモエチル)オキシランの代わりに、2-(3-ブロモプロピル)オキシランを用いたことと、第二反応において式(11)で表される化合物の代わりに、下記式(19)で表される化合物を3.35g用いたこと以外は、実施例1と同様な操作を行い、上記式(H)で表される化合物(式(H)中のFph1、Fph2は式(HF)で表される。Fph1中の平均重合度を示すrhは2.5であり、Fph2中の平均重合度を示すrhは2.5である。)を3.2g(分子量1777、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.65(16H)、3.42~4.35(38H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
第一反応において2-(2-ブロモエチル)オキシランの代わりに、2-(3-ブロモプロピル)オキシランを用いたことと、第二反応において式(13)で表される化合物の代わりに、下記式(20)で表される化合物を6.99g用いたこと以外は、実施例2と同様な操作を行い、上記式(I)で表される化合物(式(I)中のFdi1、Fdi2は式(IF)で表される。Fdi1中の平均重合度を示すqiは2.5、Fdi2中の平均重合度を示すqiは2.5である。)を4.8g(分子量2688、1.8mmol)得た。
エチレングリコールモノアリルエーテルを、ジヒドロピランを用いて保護した化合物を酸化させて、第1化合物を得た。第1化合物と、4-ペンテン-1-オールの水酸基とを反応させて、第2化合物を得た。第2化合物の2級水酸基をTHP基で保護した化合物の二重結合を酸化した。以上の工程により、式(20)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.38~1.58(16H)、3.38~4.41(58H)
19F-NMR(acetone-D6):δ[ppm]=-84.0~-83.0(30F)、-86.4(12F)、-124.3(12F)、-130.0~-129.0(15F)
第一反応において2-(2-ブロモエチル)オキシランの代わりに、2-(3-ブロモプロピル)オキシランを用いたことと、第二反応において式(14)で表される化合物の代わりに、下記式(21)で表される化合物を5.77g用いたこと以外は、実施例3と同様な操作を行い、上記式(J)で表される化合物(式(J)におけるFfj1、Ffj2は式(JF)で表される。Ffj1中の平均重合度を示すsj、tjは2.5、Ffj2中の平均重合度を示すsj、tjは2.5である。)を4.4g(分子量2452、1.8mmol)得た。
3-アリルオキシ-1,2-プロパンジオールの有する1級水酸基に、保護基としてtert-ブチルジメチルシリル(TBS)基を導入し、得られた化合物の2級水酸基に保護基としてメトキシメチル(MOM)基を導入した。その後、化合物からTBS基を除去し、生じた1級水酸基に2-ブロモエトキシテトラヒドロピランを反応させた。得られた化合物の二重結合を酸化した。以上の工程により、式(21)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.66(8H)、3.39~4.35(58H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(15F)、-77.7(6F)、-80.3(6F)、-91.0~-88.5(30F)
第二反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物(数平均分子量693、分子量分布1.1)を20.8g用いたことと、式(11)で表される化合物の代わりに、上記式(18)で表される化合物を4.51g用いたこと以外は、実施例1と同様な操作を行い、上記式(K)で表される化合物(式(K)中のFdk1、Fpk1は式(KF)で表される。Fdk1中の平均重合度を示すqkは2.5であり、Fpk1中の平均重合度を示すrkは2.5である)を4.2g(分子量2319、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.63(8H)、3.39~4.35(50H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(2F)、-81.3(2F)、-84.0~-83.0(20F)、-86.4(8F)、-90.0~-88.5(10F)、-124.3(8F)、-130.0~-129.0(10F)
第二反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物(数平均分子量633、分子量分布1.1)を用いたことと、式(11)で表される化合物の代わりに、下記式(22)で表される化合物を6.02g用いたこと以外は、実施例1と同様な操作を行い、上記式(L)で表される化合物(式(L)中のFfl1、Fpl1は式(LF)で表される。Ffl1中の平均重合度を示すsl、tlは2.5であり、Fpl1中の平均重合度を示すrlは2.5である。)を4.1g(分子量2287、1.8mmol)得た。
ジヒドロピランを用いて、エチレングリコールモノアリルエーテルを保護し、得られた化合物を酸化して第1化合物とした。次に、第1化合物と、3-ブテン-1-オールの水酸基とを反応させて第2化合物とした。得られた第2化合物の2級水酸基をMOM基で保護し、二重結合を酸化させることにより、式(22)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.35~1.62(8H)、3.41~4.35(58H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
第二反応においてHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物の代わりに、HOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物(数平均分子量693、分子量分布1.1)を20.8g用いたことと、式(19)で表される化合物の代わりに、上記式(11)で表される化合物を3.89g用いたこと以外は、実施例8と同様な操作を行い、上記式(M)で表される化合物(式(M)中のFdm1、Fpm1は式(MF)で表される。Fdm1中の平均重合度を示すqmは2.5であり、Fpm1中の平均重合度を示すrmは2.5である。)を4.1g(分子量2287、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.35~1.56(12H)、3.41~4.37(46H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(2F)、-81.3(2F)、-84.0~-83.0(20F)、-86.4(8F)、-90.0~-88.5(10F)、-124.3(8F)、-130.0~-129.0(10F)
第二反応においてHOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物(数平均分子量468、分子量分布1.1)を14.0g用いたこと以外は、実施例2と同様な操作を行い、上記式(N)で表される化合物(式(N)中のFdn1、Fpn1は式(NF)で表される。Fdn1中の平均重合度を示すqnは2.5であり、Fpn1中の平均重合度を示すrnは2.5である。)を3.9g(分子量2182、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.39~1.61(8H)、3.41~4.45(58H)
19F-NMR(acetone-D6):δ[ppm]=-78.6(4F)、-81.3(4F)、-84.0~-83.0(10F)、-86.4(4F)、-90.0~-88.5(24F)、-124.3(4F)、-130.0~-129.0(5F)
第二反応において上記式(13)で表される化合物の代わりに、上記式(15)で表される化合物を4.76g用いたこと以外は、実施例14と同様な操作を行い、上記式(O)で表される化合物(式(O)中のFdo1、Fpo1は式(OF)で表される。Fdo1中の平均重合度を示すqoは2.5であり、Fpo1中の平均重合度を示すroは2.5である。)を3.8g(分子量2122、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.58(12H)、3.38~4.41(50H)
19F-NMR(acetone-D6):δ[ppm]=-78.6(4F)、-81.3(4F)、-84.0~-83.0(10F)、-86.4(4F)、-90.0~-88.5(24F)、-124.3(4F)、-130.0~-129.0(5F)
第二反応においてHOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物(数平均分子量633、分子量分布1.1)を用いたことと、上記式(13)で表される化合物の代わりに、下記式(23)で表される化合物を4.15g用いたこと以外は、実施例2と同様な操作を行い、上記式(P)で表される化合物(式(P)中のFdp1、Ffp1は式(PF)で表される。Fdp1中の平均重合度を示すqpは2.5を表す。Ffp1中の平均重合度を示すsp、tpは2.5である。)を4.3g(分子量2392、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.37~1.61(12H)、3.40~4.43(46H)
19F-NMR(acetone-D6):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-80.3(4F)、-84.0~-83.0(10F)、-86.4(4F)、-91.0~-88.5(20F)、-124.3(4F)、-130.0~-129.0(5F)
第二反応においてHOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物(数平均分子量633、分子量分布1.1)を用いたことと、上記式(20)で表される化合物の代わりに、上記式(16)で表される化合物を3.64g用いたこと以外は、実施例9と同様な操作を行い、上記式(Q)で表される化合物(式(Q)中のFdq1、Ffq1は式(QF)で表される。Fdq1中の平均重合度を示すqqは2.5であり、Ffq1中の平均重合度を示すsq、tqは2.5である。)を4.3g(分子量2364、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.36~1.57(8H)、3.39~4.37(46H)
19F-NMR(acetone-D6):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-80.3(4F)、-84.0~-83.0(10F)、-86.4(4F)、-91.0~-88.5(20F)、-124.3(4F)、-130.0~-129.0(5F)
第二反応においてHOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物(数平均分子量468、分子量分布1.1)を14.0g用いたことと、上記式(14)で表される化合物の代わりに、上記式(21)で表される化合物を5.77g用いたこと以外は、実施例3と同様な操作を行い、上記式(R)で表される化合物(式(R)中のFfr1、Fpr1は式(RF)で表される。Ffr1中の平均重合度を示すsr、trは2.5であり、Fpr1中の平均重合度を示すrrは2.5である。)を3.8g(分子量2094、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.59(4H)、3.40~4.43(58H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(5F)、-77.7(2F)、-78.6(4F)、-80.3(2F)、-81.3(4F)、-90.0~-88.5(30F)
第二反応においてHOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物の代わりに、HOCH2CF2CF2O(CF2CF2CF2O)qCF2CF2CH2OH(式中の平均重合度を示すqは2.5である。)で表される化合物(数平均分子量693、分子量分布1.1)を20.8g用いたことと、上記式(14)で表される化合物の代わりに、下記式(24)で表される化合物を3.61g用いたこと以外は、実施例3と同様な操作を行い、上記式(S)で表される化合物(式(S)中のFds1、Ffs1は式(SF)で表される。Fds1中の平均重合度を示すqsは2.5であり、Ffs1中の平均重合度を示すss、tsは2.5である。)を4.3g(分子量2392、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.57(16H)、3.41~4.37(38H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(5F)、-77.7(2F)、-80.3(2F)、-84.0~-83.0(20F)、-86.4(8F)、-91.0~-88.5(10F)、-124.3(8F)、-130.0~-129.0(10F)
第二反応においてHOCH2CF2O(CF2CF2O)s(CF2O)tCF2CH2OH(式中の平均重合度を示すs、tは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物(数平均分子量468、分子量分布1.1)を用いたことと、上記式(21)で表される化合物の代わりに、下記式(25)で表される化合物を5.48g用いたこと以外は、実施例10と同様な操作を行い、上記式(T)で表される化合物(式(T)中のFft1、Fpt1は式(TF)で表される。Fft1中の平均重合度を示すst、ttは2.5であり、Fpt1中の平均重合度を示すrtは2.5である。)を3.76g(分子量2090、1.8mmol)得た。
式(19)で表される化合物とアリルアルコールとを反応させて得られた化合物の2級水酸基をMOM基で保護した。得られた化合物の二重結合を酸化させることにより式(25)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.35~1.60(16H)、3.42~4.42(50H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(5F)、-77.7(2F)、-78.6(4F)、-80.3(2F)、-81.3(4F)、-90.0~-88.5(30F)
下記式(AA)で表される化合物を、特許文献1に記載の方法で合成した。
1H-NMR(CD3COCD3):δ[ppm]=3.42~4.28(38H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AB)で表される化合物を、特許文献1に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=1.54~1.76(4H)、3.42~4.28(38H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AC)で表される化合物を、特許文献1に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=3.46~4.18(46H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AD)で表される化合物を、特許文献1に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.67(4H)、3.39~4.34(46H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AE)で表される化合物を、特許文献2に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.65(8H)、3.42~4.35(46H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AF)で表される化合物を、以下の方法で合成した。
第一反応において2-(2-ブロモエチル)オキシランの代わりに、エピブロモヒドリンを用いたことと、第二反応において式(22)で表される化合物の代わりに、下記式(26)で表される化合物を4.47g用いたこと以外は、実施例12と同様な操作を行い、下記式(AF)で表される化合物を3.9g(分子量2143、1.8mmol)得た。
(式(26)中、THPはテトラヒドロピラニル基を表す。)
(式(AF)中のFpaf1、Ffaf1は式(AFF)で表される。Fpaf1中の平均重合度を示すpafは2.5であり、Ffaf1中の平均重合度を示すmaf、nafはそれぞれ2.5を表す。)
1H-NMR(CD3COCD3):δ[ppm]=3.42~4.35(50H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AG)で表される化合物を、特許文献2に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=1.54~1.76(2H)、3.42~4.28(32H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(10F)、-77.7(4F)、-78.6(2F)、-80.3(4F)、-81.3(2F)、-90.0~-88.5(30F)
下記式(AH)で表される化合物を、特許文献1に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=3.42~4.28(38H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(5F)、-77.7(2F)、-78.6(4F)、-80.3(2F)、-81.3(4F)、-90.0~-88.5(30F)
下記式(AI)で表される化合物を、特許文献1に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=3.42~4.28(38H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
下記式(AJ)で表される化合物を、特許文献1に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=3.42~4.28(38H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(15F)、-77.7(6F)、-80.3(6F)、-91.0~-88.5(30F)
下記式(AK)で表される化合物を、特許文献2に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=1H-NMR(CD3COCD3):δ[ppm]=3.46~4.18(46H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
下記式(AL)で表される化合物を、特許文献2に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=1H-NMR(CD3COCD3):δ[ppm]=3.46~4.18(46H)
19F-NMR(CD3COCD3):δ[ppm]=-55.6~-50.6(15F)、-77.7(6F)、-80.3(6F)、-91.0~-88.5(30F)
下記式(AM)で表される化合物を、特許文献2に記載の方法で合成した。
(同定データ)
1H-NMR(CD3COCD3):δ[ppm]=3.46~4.18(32H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
下記式(AN)で表される化合物を、以下の方法で合成した。
窒素ガス雰囲気下、200mLナスフラスコにHOCH2CF2O(CF2CF2O)rCF2CH2OH(式中の平均重合度を示すrは2.5である。)で表される化合物(数平均分子量468、分子量分布1.1)14.0gと、tert-ブチルグリシジルエーテル2.34g(分子量130.19、18mmol)と、t-ブタノール28mLとを仕込み、室温で均一になるまで撹拌した。この均一の液にさらにカリウムtert-ブトキシド1.0g(分子量112.2、9mmol)を加え、70℃で16時間撹拌して反応させた。
式(28)で表される化合物は、ジアリルエーテルを酸化させることによって合成した。
1H-NMR(CD3COCD3):δ[ppm]=3.47~4.24(50H)
19F-NMR(CD3COCD3):δ[ppm]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
実施例1~20、比較例1~14で得られた化合物を、それぞれフッ素系溶媒であるバートレル(登録商標)XF(商品名、三井デュポンフロロケミカル社製)に溶解し、保護層上に塗布した時の塗膜の膜厚が9Å~11ÅになるようにバートレルXFで希釈し、潤滑層形成用溶液とした。
直径65mmの基板上に、付着層と軟磁性層と第1下地層と第2下地層と磁性層と保護層とを順次設けた磁気記録媒体を用意した。保護層は、厚み1~5nmの炭素からなるものとした。
保護層までの各層の形成された磁気記録媒体の保護層上に、実施例1~20、比較例1~14の潤滑層形成用溶液を、それぞれディップ法により塗布した。なお、ディップ法は、浸漬速度10mm/sec、浸漬時間30sec、引き上げ速度1.2mm/secの条件で行った。
バーニッシュ工程後の磁気記録媒体を、120℃の恒温槽に入れ、10分間加熱する熱処理を行った。
以上の工程により、実施例1~20、比較例1~14の磁気記録媒体(バーニッシュ有り)を得た。
また、バーニッシュ工程を行わなかったこと以外は、バーニッシュ有りの磁気記録媒体と同様にして、実施例1~20、比較例1~14の磁気記録媒体(バーニッシュ無し)を得た。
このようにして得られた実施例1~20、比較例1~14の磁気記録媒体(バーニッシュ有りおよび無し)の有する潤滑層の膜厚を、フーリエ変換赤外分光光度計(FT-IR)(商品名:Nicolet iS50、Thermo Fisher Scientific社製)を用いて測定した。実施例1~20、比較例1~14の磁気記録媒体のいずれにおいても、バーニッシュ有りと無しとで潤滑層の膜厚に差はなかった。その結果を表3に示す。
(耐腐食性試験)
磁気記録媒体を85℃相対湿度90%の条件下に48時間曝露した。その後、磁気記録媒体の腐食した場所の数を、光学表面分析装置を用いて数え、以下の評価基準に基づいて評価した。その結果を表3に示す。
A:120未満
B:120以上、150未満
C:150以上、350未満
D:350以上、1000未満
E:1000以上
これに対し、比較例1~14の磁気記録媒体は、テープバーニッシュ無しの場合も有りの場合も、耐腐食性試験の結果がC~Eであり、実施例1~20の磁気記録媒体と比較して、耐腐食性が劣っていた。
Claims (11)
- 下記式(1)で表されることを特徴とする含フッ素エーテル化合物。
R1-CH2-R2-CH2-R3-CH2-R4-CH2-R5-CH2-R6-CH2-R7
(1)
(式(1)中、R2、R4およびR6は、同じまたは異なるパーフルオロポリエーテル鎖である;R3は下記式(2)で表される連結基である;R5は下記式(3)で表される連結基である;R1およびR7はそれぞれ独立に、2つまたは3つの極性基を含み、各極性基がそれぞれ異なる炭素原子に結合し、前記極性基の結合している炭素原子同士が、極性基の結合していない炭素原子を含む連結基を介して結合している末端基である。)
(式(2)中のaは1~3の整数であり、bは1~2の整数である;式(3)中のcは1~3の整数であり、dは1~2の整数である;ただし、式(2)中のaと式(3)中のcが同時に1となることはない。) - 前記式(2)中のaが2~3の整数であり、前記式(3)中のcが2~3の整数である請求項1に記載の含フッ素エーテル化合物。
- 前記式(1)において、R1およびR7の有する極性基がすべて水酸基である請求項1または請求項2に記載の含フッ素エーテル化合物。
- 前記式(1)におけるR2、R4、R6がそれぞれ独立に、下記式(5)~(9)のいずれかである請求項1~請求項4のいずれか一項に記載の含フッ素エーテル化合物。
-CF2O-(CF2CF2O)k-(CF2O)l-CF2- (5)
(式(5)中、kおよびlは平均重合度を示し、それぞれ0.1~20を表す。)
-CF2O-(CF2CF2O)m-CF2- (6)
(式(6)中、mは平均重合度を示し、0.1~20を表す。)
-CF2CF2O-(CF2CF2CF2O)n-CF2CF2- (7)
(式(7)中、nは平均重合度を示し、0.1~20を表す。)
-CF2CF2CF2O-(CF2CF2CF2CF2O)o-CF2CF2CF2- (8)
(式(8)中、oは平均重合度を示し、0.1~10を表す。)
-CF(CF3)O-(CF2CF(CF3)O)p-CF(CF3)- (9)
(式(9)中のpは平均重合度を示し、0.1~20を表す。) - 前記式(1)において、R1とR7が同じである請求項1~請求項5のいずれか一項に記載の含フッ素エーテル化合物。
- 前記式(1)において、R2とR6が同じである請求項1~請求項6のいずれか一項に記載の含フッ素エーテル化合物。
- 数平均分子量が500~10000の範囲内である請求項1~請求項7のいずれか一項に記載の含フッ素エーテル化合物。
- 請求項1~請求項8のいずれか一項に記載の含フッ素エーテル化合物を含むことを特徴とする磁気記録媒体用潤滑剤。
- 基板上に、少なくとも磁性層と、保護層と、潤滑層とが順次設けられた磁気記録媒体であって、
前記潤滑層が、請求項1~請求項8のいずれか一項に記載の含フッ素エーテル化合物を含むことを特徴とする磁気記録媒体。 - 前記潤滑層の平均膜厚が、0.5nm~2.0nmである請求項10に記載の磁気記録媒体。
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