WO2022215726A1 - 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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- WO2022215726A1 WO2022215726A1 PCT/JP2022/017256 JP2022017256W WO2022215726A1 WO 2022215726 A1 WO2022215726 A1 WO 2022215726A1 JP 2022017256 W JP2022017256 W JP 2022017256W WO 2022215726 A1 WO2022215726 A1 WO 2022215726A1
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- 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
- C08G67/00—Macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing oxygen or oxygen and carbon, not provided for in groups C08G2/00 - C08G65/00
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- 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
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- 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
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- 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
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
-
- 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
- C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
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- 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
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- 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
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 Document 1 discloses a magnetic disk provided with a lubricating layer containing a fluorine-containing ether compound having 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 its molecule and having two hydroxyl groups in the linking groups between the perfluoropolyether chains. ing.
- the present invention has been made in view of the above circumstances, and a fluorine-containing ether suitable as a material for a lubricant for a magnetic recording medium capable of forming a lubricating layer having excellent wear resistance and an effect of suppressing corrosion of a magnetic recording medium.
- the object is to provide compounds.
- Another object of the present invention is to provide a lubricant for magnetic recording media, which contains the fluorine-containing ether compound of the present invention and is capable of forming a lubricating layer having excellent wear resistance and an effect of inhibiting 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 wear resistance and 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 2 , R 4 and R 6 are perfluoropolyether chains having the same structure;
- R 3 and R 5 are each independently a linking group containing one or more hydroxyl groups.
- R 1 and R 7 are each independently a terminal group represented by the following formula (2).) —O—CH 2 —CH(OH)—([D]—CH(OH)) s —[E]—CH 2 OH (2) (In formula (2), s is 0 or 1; [D] and [E] are each independently 2 to 5 methylene groups (—CH 2 —) and one oxygen atom (—O—) A chain structure consisting of a combination, or a chain structure consisting of 1 to 4 methylene groups (—CH 2 —); provided that when s is 0 and [E] contains an oxygen atom, [E] The number of methylene groups contained is 3 or more.)
- 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.
- the terminal group represented by the formula (2) is a terminal group represented by any one of the following formulas (2-1) to (2-3) and (3-1) to (3-4) The fluorine-containing ether compound according to [1].
- 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 is a lubricant for magnetic recording media capable of forming a lubricating layer having excellent wear resistance and an effect of inhibiting corrosion of magnetic recording media. Can be used as material. 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 having excellent wear resistance and an effect of 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 wear resistance and 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 having excellent wear resistance and an effect of 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
- the lubricating layer containing the fluorine-containing ether compound having the chain skeleton When the lubricating layer containing the fluorine-containing ether compound having the chain skeleton is formed on the protective layer, both ends of the perfluoropolyether chain located at the center of the chain skeleton are separated from each other between the perfluoropolyether chains. It adheres to the protective layer due to the hydroxyl group of the linking group. 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.
- the mobility of the perfluoropolyether chain within the molecule varies depending on the structure of the perfluoropolyether chain. Since the above fluorine-containing ether compound having a chain skeleton has three perfluoropolyether chains having the same structure, the molecular distortion due to the difference in mobility between the perfluoropolyether chains is less likely to occur. Therefore, the above fluorine-containing ether compound having a chain skeleton has better molecular linearity than a compound in which perfluoropolyether chains having different structures are mixed in the molecule. As a result, the lubricant containing the fluorine-containing ether compound having a chain skeleton can uniformly adhere to the protective layer, and can form a lubricating layer with high coverage and good adhesion.
- the terminal group represented by formula (2) has two or three hydroxyl groups, and the distance between the hydroxyl groups is appropriate.
- the terminal group represented by formula (2) has a linking group arranged between the carbon atom to which the terminal hydroxyl group (terminal hydroxyl group) is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded. , the number of methylene groups contained in the above linking group is appropriate even when oxygen atoms are included.
- the lubricating layer containing the fluorine-containing ether compound having the terminal group represented by the formula (2) bonded to each end of the chain skeleton has appropriate hydrophobicity and is compatible with the protective layer. It is presumed that the adhesion will be excellent.
- the inventors of the present invention conducted further studies and confirmed that a lubricating layer containing the above-mentioned fluorine-containing ether compound was formed on the protective layer, and that excellent wear resistance and an effect of suppressing corrosion of the magnetic recording medium could be obtained. The present invention was conceived.
- 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 2 , R 4 and R 6 are perfluoropolyether chains having the same structure;
- R 3 and R 5 are each independently a linking group containing one or more hydroxyl groups.
- R 1 and R 7 are each independently a terminal group represented by the following formula (2).) —O—CH 2 —CH(OH)—([D]—CH(OH)) s —[E]—CH 2 OH (2) (In formula (2), s is 0 or 1; [D] and [E] are each independently 2 to 5 methylene groups (—CH 2 —) and one oxygen atom (—O—) A chain structure consisting of a combination, or a chain structure consisting of 1 to 4 methylene groups (—CH 2 —); provided that when s is 0 and [E] contains an oxygen atom, [E] The number of methylene groups contained is 3 or more.)
- R 1 and R 7 are each independently a terminal group represented by formula (2).
- the terminal group represented by formula (2) contains two or three hydroxyl groups. Specifically, when s in the terminal group represented by formula (2) is 0, two hydroxyl groups are included, and when s is 1, three hydroxyl groups are included.
- each of R 1 and R 7 has two or three hydroxyl groups. , a favorable interaction occurs between the lubricating layer and the protective layer.
- the total number of hydroxyl groups contained in R 1 and hydroxyl 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 hydroxyl groups contained in R 1 and the number of hydroxyl groups contained in R 7 are preferably the same. That is, each of R 1 and R 7 contains two hydroxyl groups (for example, each of R 1 and R 7 is represented by any one of the following formulas (2-1) to (2-3)), or R 1 and R 7 each contain three hydroxyl groups (eg, each of R 1 and R 7 is represented by one of the following formulas (3-1) to (3-4)).
- 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.
- the hydroxyl groups contained in the fluorine-containing ether compound can firmly adhere to the protective layer, resulting in high coverage and excellent abrasion resistance.
- Each hydroxyl group contained in R 1 and R 7 is bonded to a different carbon atom.
- the carbon atoms to which hydroxyl groups are bonded are bonded via a linking group containing a carbon atom to which no hydroxyl group is 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 carbon atoms to which hydroxyl 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 terminal group represented by formula (2) is a linear link having an appropriate number of carbon atoms between the carbon atom to which the hydroxyl group is bonded and the carbon atom to which the hydroxyl group adjacent to the hydroxyl group is bonded. base is placed. Therefore, the distance between the hydroxyl groups contained in the terminal groups represented by formula (2) is appropriate. Furthermore, the terminal group represented by formula (2) has a linking group arranged between the carbon atom to which the terminal hydroxyl group (terminal hydroxyl group) is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded. , the number of methylene groups contained in the above linking group is appropriate even when oxygen atoms are included.
- the lubricating layer containing the fluorine-containing ether compound of the present embodiment has appropriate hydrophobicity and excellent adhesion to the protective layer. As a result, excellent wear resistance and an effect of suppressing corrosion of the magnetic recording medium can be obtained.
- the linking group arranged 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 (ether bond)
- the methylene contained in the linking group If the number of groups is too small, intramolecular aggregation between the terminal hydroxyl group and the adjacent hydroxyl group is likely to occur due to the flexibility resulting from the ether bond. On the other hand, if the number of methylene groups contained in the linking group is too large, the hydrophobicity becomes too high, resulting in insufficient adhesion to the protective layer.
- [D] and [E] are each independently a chain structure consisting of a combination of 2 to 5 methylene groups (—CH 2 —) and one oxygen atom (—O—), or 1 It is a chain structure consisting of ⁇ 4 methylene groups ( -CH2- ).
- a chain structure consisting of a combination of 2 to 5 methylene groups and one oxygen atom if the left side is the perfluoropolyether side and the right side is the terminal side, for example, —CH 2 —O—CH 2 —, — CH 2 —O—CH 2 CH 2 —, —CH 2 —O—CH 2 CH 2 CH 2 —, —CH 2 CH 2 —O—CH 2 —, —CH 2 CH 2 —O—CH 2 CH 2 — , -CH 2 CH 2 -O-CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 -O-CH 2 -, -CH 2 CH 2 CH 2 -O-CH 2 CH 2 -, etc. .
- [D] is preferably a chain structure consisting of a combination of 2 to 5 methylene groups and one oxygen atom, since moderate flexibility can be obtained by containing an ether bond, and 2 to 4 methylene groups. and one oxygen atom.
- formula (2) when s is 0 and [E] contains an oxygen atom, the number of methylene groups contained in [E] is 3 or more. That is, when [E] contains an oxygen atom, [E] is a chain structure consisting of a combination of 3 to 5 methylene groups (--CH.sub.2--) and one oxygen atom (--O--).
- the terminal group represented by formula (2) is represented by the following formulas (2-1) to (2-3), (3-1) to (3-4) ) is preferably a terminal group represented by any one of In this case, it is possible to form a lubricating layer having more excellent wear resistance and an effect of suppressing corrosion of the magnetic recording medium.
- at least one of R 1 and R 7 is preferably a terminal group represented by any one of formulas (3-1) to (3-4).
- R 1 and/or R 7 is a fluorine-containing group containing three hydroxyl groups It becomes an ether compound. As a result, it is possible to form a lubricating layer that is even more excellent in adhesion to the protective layer and has better wear resistance.
- the terminal group represented by the above formula (2-1) has two hydroxyl groups.
- the terminal groups represented by formulas (3-1) and (3-4) each have three hydroxyl groups.
- the terminal groups represented by the above formulas (2-1), (3-1), and (3-4) are all the carbon atoms to which the terminal hydroxyl groups are bonded and the carbon atoms to which the hydroxyl groups adjacent to the terminal hydroxyl groups are bonded. does not contain an oxygen atom.
- the linking groups of the terminal groups represented by the above formulas (2-1), (3-1), and (3-4) are linear chains containing 1 to 4 carbon atoms to which no hydroxyl group is bonded. It has a similar structure.
- the linking group does not contain an oxygen atom and has a linear structure containing one or more carbon atoms to which no hydroxyl group is bonded
- the resulting fluorine-containing ether compound has good hydrophobicity.
- the linking group has a linear structure containing 4 or less carbon atoms
- the linking group is too hydrophobic to interfere with the adhesion to the protective layer.
- the terminal groups represented by the above formulas (2-1), (3-1), and (3-4) are 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 lubricating layer containing the fluorine-containing ether compound, in which the linking group has a linear structure containing the number of carbon atoms within the above range exhibits high wear resistance, can prevent water from entering, and is effective for magnetic recording media. It becomes a thing with a high corrosion inhibitory effect.
- the terminal groups represented by formulas (2-2) and (2-3) each have two hydroxyl groups.
- a linking group arranged 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 linking group is a linear structure containing 3 to 5 carbon atoms to which no hydroxyl group is attached. Even when the linking group contains an oxygen atom, if it has a linear structure containing three or more carbon atoms to which no hydroxyl 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. Therefore, the lubricating layer containing the fluorine-containing ether compound, in which the linking group has a linear structure containing the number of carbon atoms within the above range, exhibits high wear resistance, can prevent water from entering, and is effective for magnetic recording media. It becomes a thing with a high corrosion inhibitory effect.
- the linking group has a linear structure composed of 4 to 6 atoms.
- the number of atoms contained in the linking group is within the above range, even if the linking group contains an oxygen atom, the molecular mobility becomes appropriate, intramolecular aggregation is less likely to occur, and excellent adhesion with the protective layer is achieved. A lubricating layer having properties is obtained.
- the terminal groups represented by formulas (3-2) and (3-3) each have three hydroxyl groups.
- a linking group arranged 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 linking group is a linear structure containing 2 to 4 carbon atoms to which no hydroxyl group is attached. Even when the linking group contains an oxygen atom, if it has a linear structure containing two or more carbon atoms to which no hydroxyl group is bonded, the fluorine-containing ether compound has good hydrophobicity.
- the linking group has a linear structure containing 4 or less carbon atoms
- the linking group is too hydrophobic to interfere with the adhesion to the protective layer.
- the terminal groups represented by formulas (3-2) and (3-3) have three hydroxyl groups, In the case of a straight-chain structure containing the above carbon atoms, a lubricating layer having excellent adhesion to the protective layer can be obtained. Therefore, the lubricating layer containing the fluorine-containing ether compound, in which the linking group has a linear structure containing the number of carbon atoms within the above range, exhibits high wear resistance, can prevent water from entering, and is effective for magnetic recording media.
- the linking group has a linear structure of 3 to 5 atoms.
- the number of atoms contained in the linking group is within the above range, even if the linking group contains an oxygen atom, the molecular mobility becomes appropriate, intramolecular aggregation is less likely to occur, and excellent adhesion with the protective layer is achieved. A lubricating layer having properties is obtained.
- the terminal group represented by formula (2-1) has a chain structure in which s in formula (2) is 0 and [E] is 1 to 4 methylene groups.
- a is an integer of 1-4. Since 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, it exhibits appropriate hydrophobicity. In addition, since a 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 is small.
- the fluorine-containing ether compound having a terminal group represented by formula (2-1) is less prone to intramolecular aggregation, has excellent adhesion to the protective layer, and has excellent wear resistance. It can form layers.
- the terminal group represented by formula (2-2) is a chain structure in which s in formula (2) is 0 and [E] is a combination of 3 to 4 methylene groups and one oxygen atom. .
- b is an integer of 2-3. Therefore, it becomes a fluorine-containing ether compound having good hydrophobicity, and exhibits an excellent effect of suppressing corrosion of 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 the formula (2-2) has b of 2 to 3, the molecular mobility is appropriate, the intramolecular aggregation of the hydroxyl groups is unlikely to occur, and the protective layer is excellent.
- a lubricating layer having adhesion and excellent wear resistance can be formed.
- the terminal group represented by formula (2-3) is a chain structure in which s in formula (2) is 0 and [E] is a combination of 3 to 5 methylene groups and one oxygen atom. .
- c is an integer of 1-3. Therefore, it becomes a fluorine-containing ether compound having good hydrophobicity, and exhibits an excellent effect of suppressing corrosion of 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 the formula (2-3) has c of 1 to 3, the molecular mobility is appropriate, the intramolecular aggregation of the hydroxyl groups is unlikely to occur, and the protective layer is excellent. It is possible to form a lubricating layer having good adhesion and excellent wear resistance.
- the terminal group represented by formula (3-1) is a chain structure in which s in formula (2) is 1, [D] is a combination of two methylene groups and one oxygen atom, and [ E] is a chain structure consisting of 1 to 4 methylene groups.
- d is an integer of 1-4. Since 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, it exhibits appropriate hydrophobicity.
- 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, and Since it contains three hydroxyl groups, it has excellent adhesion to the protective layer and can form a lubricating layer having excellent wear resistance.
- the terminal group represented by formula (3-2) is a chain structure in which s in formula (2) is 1, [D] is a combination of two methylene groups and one oxygen atom, and [ E] is a chain structure consisting of a combination of 2 to 4 methylene groups and one oxygen atom.
- e is an integer of 1-3. Therefore, it becomes a fluorine-containing ether compound having good hydrophobicity, and exhibits an excellent effect of suppressing corrosion of magnetic recording media.
- the terminal group represented by formula (3-2) contains three hydroxyl groups, it has excellent adhesion to the protective layer and can form a lubricating layer having excellent wear resistance.
- the terminal group represented by formula (3-3) is a chain structure in which s in formula (2) is 1 and [D] is a combination of 3 to 4 methylene groups and one oxygen atom.
- [E] is a chain structure consisting of a combination of two methylene groups and one oxygen atom.
- f is an integer of 1-2. Therefore, it becomes a fluorine-containing ether compound having good hydrophobicity, and exhibits an excellent effect of suppressing corrosion of magnetic recording media.
- the terminal group represented by formula (3-3) contains three hydroxyl groups, it has excellent adhesion to the protective layer and can form a lubricating layer having excellent wear resistance.
- the terminal group represented by formula (3-4) is a chain structure in which s in formula (2) is 1, [D] is a combination of three methylene groups and one oxygen atom, and [ E] is a chain structure consisting of one methylene group.
- 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 becomes a fluorine-containing ether compound having good hydrophobicity, and exhibits an excellent effect of suppressing corrosion of magnetic recording media.
- the terminal group represented by formula (3-4) contains three hydroxyl groups, it has excellent adhesion to the protective layer and can form a lubricating layer having excellent wear resistance.
- 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 and excellent abrasion resistance, 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 3 and R 5 are each independently a linking group containing one or more hydroxyl groups.
- the hydroxyl group contained in R3 and R5 improves the adhesion of the lubricating layer containing the fluorine - containing ether compound to the protective layer.
- the number of hydroxyl groups contained in R 3 and R 5 is preferably 1 to 4, more preferably 1 to 2, so that a proper coverage can be maintained, and the hydrophobicity of the molecule is appropriate. Therefore, it is more preferable to be 1.
- R 3 and R 5 are divalent linking groups that bond to the methylene groups (—CH 2 —) located on both sides.
- R 3 and R 5 are preferably alkylene groups having one or more hydroxyl groups and containing an ether bond (--O--).
- the number of carbon atoms contained in R 3 and R 5 is preferably 3 to 12, more preferably 3 to 6, even more preferably 3.
- R 3 and R 5 are preferably a linking group represented by the following formula (4).
- g is an integer of 1-4.
- the hydroxyl group of the linking group represented by formula (4) improves the adhesion of the lubricating layer containing the fluorine-containing ether compound to the protective layer.
- g 1, synthesis of the fluorine-containing ether compound is easy, which is preferable.
- R 3 and R 5 are the linking groups represented by formula (4)
- the oxygen atoms arranged at both ends of R 3 and R 5 are the linking groups represented by formula (4), respectively. It combines with the methylene groups (--CH.sub.2--) located on both sides to form an ether bond (--O--).
- R 2 , R 4 and R 6 are perfluoropolyether chains (PFPE chains) having the same structure.
- 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 in formula (1) may be PFPE chains having the same structure, and can be appropriately selected depending on the performance required of the lubricant containing the fluorine-containing ether compound.
- Examples of the 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 preferably, for example, PFPE chains represented by formula (Rf-1) below.
- PFPE chains 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 0.1-20, preferably 0.1-15, more preferably 1-10.
- 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).
- R 2 , R 4 and R 6 in formula (1) are any one of the following formulas (5) to (9).
- R 2 , R 4 and R 6 in formula (1) are any one of the following formulas (5) to (9).
- R 2 , R 4 and R 6 in formula (1) are any 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).
- h and i indicating the average degree of polymerization in formula (5) are each 0.1 to 20, j indicating the average degree of polymerization in formula (6) is 0.1 to 20, and the average degree of polymerization in formula (7) k indicating the degree is 0.1 to 20, l indicating the average degree of polymerization in formula (8) is 0.1 to 10, r indicating the average degree of polymerization in formula (9) is 0.1 to 20 is.
- h, i, j, k, l, and r can be arbitrarily selected within the above ranges.
- a lubricating layer having good wear resistance and capable of further suppressing corrosion of the magnetic recording medium can be obtained. It becomes a fluorine-containing ether compound. Further, when each of h, i, j, k, and r indicating the average degree of polymerization is 20 or less, and l is 10 or less, the viscosity of the fluorine-containing ether compound does not become too high, and a lubricant containing the same is applied. It is easy to use and is preferable.
- Each of h, i, j, k, l, and r which indicate the average degree of polymerization, is a fluorine-containing ether compound that easily wets and 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 h, i, j, k, l, and r may be, for example, 0.5 to 9, 1 to 8, 2 to 7, 3 to 6, 4 to 5, and the like.
- 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.
- R 2 , R 4 and R 6 are PFPE chains having the same structure.
- the phrase "the PFPE chains have the same structure” includes the case where the PFPE chains have the same structure (repeating units) and different average degrees of polymerization.
- R 2 , R 4 and R 6 are all PFPE chains represented by formula (5)
- R 2 , R 4 and R 6 are all repeating units ((CF 2 CF 2 O) and ( CF 2 O)) are the same, and h and i indicating the average degree of polymerization in formula (5) may be partially or entirely the same in R 2 , R 4 and R 6 respectively, or all can be different.
- R 2 , R 4 , and R 6 are PFPE chains having the same structure, and at least R 2 and R 6 have the same average degree of polymerization, the synthesis of the fluorine-containing ether compound is facilitated, which is preferable.
- R 2 , R 4 and R 6 may be PFPE chains having the same structure, and the PFPE chains of R 2 , R 4 and R 6 may all have the same average degree of polymerization.
- the resulting fluorine-containing ether compound has less molecular distortion due to the mobility of the PFPE chains. Therefore, it is possible to uniformly adhere to the protective layer and form a lubricating layer with a high coverage.
- the fluorine-containing ether compound has a mixture of PFPE chains with different structures in the molecule (for example, R 2 and R 6 are PFPE chains represented by formula (5) and R 4 is a PFPE chain represented by formula (6)), the difference in mobility caused by the structure of each PFPE chain causes strain in the molecule, which reduces the linearity of the molecule. As a result, it is presumed that the lubricating layer cannot be uniformly adhered to the protective layer and a lubricating layer having a low coverage is formed.
- R 2 , R 4 and R 6 have the same structure. Furthermore, in the fluorine-containing ether compound represented by formula (1), it is preferable that R 3 and R 5 are the same, and R 1 and R 7 are also the same.
- Such a fluorine-containing ether compound has a symmetrical structure centering on R4 . Therefore, it is easy to uniformly wet and spread on the protective layer, and it is easy to obtain a lubricating layer having a more uniform film thickness. Further, a fluorine-containing ether compound in which 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 also the same can be easily and efficiently produced in a small number of production steps. .
- the fluorine-containing ether compound represented by formula (1) is preferably any one of compounds represented by the following formulas (A) to (M).
- formulas (A) to (M) mc, mg, mh, nc, ng, nh, pa, pd, pi, pj, qb, qe, qf, qk, ql, and qm indicate an average degree of polymerization. Since it is a value, it is not necessarily an integer.
- R 1 and R 7 are terminal groups represented by the formula (2-1), a is 2, and R 2 , R 4 and R 6 are represented by the formula ( 6) is a PFPE chain represented by In the compound represented by the following formula (B), R 1 and R 7 are terminal groups represented by the formula (2-1), a is 3, and R 2 , R 4 and R 6 are represented by the formula ( 7) is a PFPE chain represented by In the compound represented by the following formula (C), R 1 and R 7 are terminal groups represented by the formula (2-2), b is 2, and R 2 , R 4 and R 6 are represented by the formula ( 5) is a PFPE chain represented by In the compound represented by the following formula (D), R 1 and R 7 are terminal groups represented by the formula (2-2), b is 3, and R 2 , R 4 and R 6 are represented by the formula ( 6) is a PFPE chain represented by the formula (2-1), a is 2, and R 2 , R 4 and R 6 are represented by the formula ( 6) is a PFPE chain represented by In
- R 1 and R 7 are terminal groups represented by the formula (3-2), e is 1, and R 2 , R 4 and R 6 are represented by the formula ( 7) is a PFPE chain represented by In the compound represented by the following formula (F), R 1 and R 7 are terminal groups represented by the formula (3-2), e is 2, and R 2 , R 4 and R 6 are represented by the formula ( 7) is a PFPE chain represented by In the compound represented by the following formula (G), R 1 and R 7 are terminal groups represented by the formula (2-3), c is 1, and R 2 , R 4 and R 6 are represented by the formula ( 5) is a PFPE chain represented by In the compound represented by the following formula (H), R 1 and R 7 are terminal groups represented by the formula (3-3), f is 1, and R 2 , R 4 and R 6 are represented by the formula ( 5) is a PFPE chain represented by
- R 1 and R 7 are terminal groups represented by the formula (3-1), d is 1, and R 2 , R 4 and R 6 are represented by the formula ( 6) is a PFPE chain represented by In the compound represented by the following formula (J), R 1 and R 7 are terminal groups represented by the formula (3-1), d is 2, and R 2 , R 4 and R 6 are represented by the formula ( 6) is a PFPE chain represented by In the compound represented by the following formula (K), R 1 and R 7 are terminal groups represented by the formula (3-3), f is 2, and R 2 , R 4 and R 6 are represented by the formula ( 7) is a PFPE chain represented by In the compound represented by the following formula (L), R 1 and R 7 are terminal groups represented by the formula (3-4), and R 2 , R 4 and R 6 are represented by the formula (7) PFPE chains.
- R 1 and R 7 are terminal groups represented by the formula (2-1)
- a is 1, and R 2 , R 4 and R 6 are represented by the formula (6) is a PFPE
- Fpa 1 and Fpa 2 in formula (A) are represented by formula (AF).
- pa indicates an average degree of polymerization and ranges from 0.1 to 20. Pa in Fpa 1 and pa 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 formula (C) are represented by formula (CF).
- CF In Ffc 1 and Ffc 2 , mc and nc represent an average degree of polymerization, each representing 0.1 to 20. Ffc mc and nc in 1 and mc and nc in Ffc 2 may be the same or different.
- Fpd 1 and Fpd 2 in formula (D) are represented by formula (DF).
- pd indicates an average degree of polymerization and ranges from 0.1 to 20. pd in Fpd 1 and 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).
- mg and ng indicate an average degree of polymerization, each representing 0.1 to 20.
- Ffg 1 The mg and ng in and the mg and ng in Ffg 2 may be the same or different.
- Ffh 1 and Ffh 2 in formula (H) are represented by formula (HF).
- mh and nh indicate an average degree of polymerization, each representing 0.1 to 20.
- Ffh 1 mh, nh in and mh, nh in Ffh 2 may be the same or different.
- Fpi 1 and Fpi 2 in formula (I) are represented by formula (IF).
- pi indicates an average degree of polymerization and ranges from 0.1 to 20. pi in Fpi 1 and Fpi 2 may be the same or different.
- Fpj 1 and Fpj 2 in formula (J) are represented by formula (JF).
- pj indicates an average degree of polymerization and ranges from 0.1 to 20. pj in Fpj 1 and pj in Fpj 2 may be the same or different.
- Fdk 1 and Fdk 2 in formula (K) are represented by formula (KF).
- qk indicates an average degree of polymerization and ranges from 0.1 to 20.
- qk in Fdk 1 and qk in Fdk2 may be the same or different.
- Fdl 1 and Fdl 2 in formula (L) are represented by formula (LF).
- ql indicates an average degree of polymerization and ranges from 0.1 to 20.
- ql in Fdl 1 and ql in Fdl 2 may be the same or different.
- Fdm 1 and Fdm 2 in formula (M) are represented by formula (MF).
- qm indicates an average degree of polymerization and ranges from 0.1 to 20.
- qm in Fdm 1 and qm in Fdm2 may be the same or different.
- the compound represented by the formula (1) is any one of the compounds represented by the above formulas (A) to (M), the raw material is easily available and has excellent wear resistance even if the thickness is thin, It is preferable because a lubricating layer that can suppress corrosion of the magnetic recording medium can be formed.
- the compound represented by the formula (1) is any of the compounds represented by the formulas (B) and (E) to (L), particularly excellent wear resistance and corrosion inhibition effect of the magnetic recording medium can be obtained. It is more preferable because a lubricating layer can be formed.
- 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.
- 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.
- 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 it exhibits excellent wear resistance and prevents contaminants from entering the magnetic recording medium. It is highly effective in inhibiting corrosion. This effect is based on the following synergistic effects ⁇ 1> to ⁇ 5> obtained by including the fluorine-containing ether compound of the present embodiment.
- 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 hydroxyl group of R3 and the hydroxyl group of R5 , the distance between the hydroxyl group of R1 and the hydroxyl group of R3 , and the distance between the hydroxyl group of R5 and the hydroxyl group of R7 is also appropriate. Therefore, both the hydroxyl groups of R 3 and R 5 and the hydroxyl 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 hydroxyl groups.
- both the hydroxyl groups of R 3 and R 5 and the hydroxyl groups of R 1 and R 7 are likely to participate in bonding with the active sites on the protective layer.
- all of the hydroxyl groups of the fluorine-containing ether compound are unlikely to become hydroxyl 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 hydroxyl 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 hydroxyl group of R1 and the hydroxyl group of R3 , and the distance between the hydroxyl group of R5 and the hydroxyl group of R7 are all Since it is appropriate, the intramolecular interaction between the hydroxyl 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, and forms a lubricating layer with good adhesion on the protective layer. be done.
- both ends of each perfluoropolyether chain (R 2 , R 4 , R 6 ) are adhered to the protective layer by hydroxyl 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 easily wets and spreads on the protective layer, and a lubricating layer having a uniform coating state, high coverage, and good adhesion is formed on the protective layer.
- the fluorine-containing ether compound represented by formula (1) has three perfluoropolyether chains (R 2 , R 4 , R 6 ) having the same structure. Therefore, the fluorine-containing ether compound represented by the formula (1) is free from molecular distortion caused by the difference in mobility of the PFPE chains that occurs when the structures of the PFPE chains are different, and easily wets and spreads on the protective layer. Therefore, a lubricating layer having uniform coverage, high coverage, and good adhesion is formed on the protective layer.
- 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 1 and R 7 in the fluorine-containing ether compound represented by formula (1) are each independently a terminal group represented by formula (2).
- R 1 and R 7 in formula (1) each contain two or three hydroxyl groups, and the carbon atoms to which the hydroxyl groups are bonded are bonded via a linking group containing a carbon atom to which no hydroxyl group is bonded. and the distance between hydroxyl groups is appropriate. Therefore, the lubricating layer containing the fluorine-containing ether compound represented by formula (1) has appropriate hydrophobicity due to the hydrophobicity of the carbon atoms contained in the linking groups of R 1 and R 7 .
- the linking group between the carbon atom to which the terminal hydroxyl group of R 1 and R 7 is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded is When it does not contain an oxygen atom (when [E] in formula (2) is a chain structure consisting of 1 to 4 methylene groups), the intramolecular interaction between the hydroxyl groups contained in R 1 and R 7 is small. becomes. For this reason, intramolecular aggregation is unlikely to occur, and the fluorine-containing ether compound easily spreads over the protective layer, and a lubricating layer having a uniform coating state, high coverage, and good adhesion is formed on the protective layer. be done.
- the linking group between the carbon atom to which the terminal hydroxyl group of R 1 and R 7 is bonded and the carbon atom to which the hydroxyl group adjacent to the terminal hydroxyl group is bonded contains an oxygen atom ([E] in formula (2) is a chain structure consisting of a combination of 2 to 5 methylene groups and one oxygen atom)
- the distance between the hydroxyl groups contained in R 1 and R 7 is appropriate, so the molecular mobility is appropriate. becomes.
- intramolecular aggregation is less likely to occur, and a lubricating layer having uniform coating, high coverage, and good adhesion is formed on the protective layer.
- 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 contain any known material used as a lubricant material, as long as it does not impair the properties 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 exhibits excellent wear resistance and can form a lubricating layer highly effective in suppressing corrosion of the magnetic recording medium. . Since the lubricating layer made of the lubricant of the present embodiment exhibits excellent wear resistance and is highly effective in suppressing corrosion of the magnetic recording medium, the thickness can be reduced.
- 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 nonmagnetic 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 single 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 further includes oxidation. 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 enhanced.
- 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 . Also, the lubricating layer 18 reduces the frictional force of the magnetic head of the magnetic recording/reproducing device sliding 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 for 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.degree.
- 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) p CF 2 CH 2 OH (p indicating the average degree of polymerization in the formula is 2.5) was added to 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 3.45 mL (42 mmol) of epibromohydrin was added to this homogeneous liquid, and the mixture was stirred at 40° C. for 2 hours to react.
- reaction product obtained after the reaction was cooled to 25°C, 80 mL of water was added to stop the reaction, transferred to a separatory funnel, and extracted twice with 150 mL of ethyl acetate. The organic layer was washed with saturated brine 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. Obtained.
- the compound represented by formula (11) was synthesized by introducing a tetrahydropyranyl (THP) group to the primary hydroxyl group of 4-penten-1-ol and oxidizing the double bond of the resulting compound.
- THP tetrahydropyranyl
- 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.
- p 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) p CF 2 CH 2 OH (in which 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) p CF 2 CH 2 OH (p 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 (number average mole
- the compound represented by formula (13) was synthesized by introducing a tetrahydropyranyl (THP) group to the primary hydroxyl group of 5-hexen-1-ol and oxidizing the double bond of the resulting compound.
- THP tetrahydropyranyl
- THP represents a tetrahydropyranyl group.
- Example 3 In the first reaction, instead of the compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) p CF 2 CH 2 OH (in which the average degree of polymerization is 2.5), HOCH 2 CF 2 O(CF 2 CF 2 O) m (CF 2 O) n CF 2 CH 2 OH (m and n indicating the average degree of polymerization in the formula are 2.5) (number HOCH 2 CF 2 O (CF 2 CF 2 O) p CF 2 CH 2 OH (in the formula, the average degree of polymerization is p is 2.5.) instead of the compound represented by HOCH 2 CF 2 O(CF 2 CF 2 O) m (CF 2 O) n CF 2 CH 2 OH (in which the average degree of polymerization is m and n shown are 2.5.) Using 19.0 g of a compound represented by (number average molecular weight 633, molecular weight distribution 1.1), , except that 3.89 g of the compound
- the compound represented by formula (14) was synthesized by protecting one hydroxyl group of 1,3-propanediol with a tetrahydropyranyl (THP) group and reacting the other hydroxyl group with epibromohydrin. .
- THP tetrahydropyranyl
- THP represents a tetrahydropyranyl group.
- Example 4 In the second reaction, the same operation as in Example 1 was performed except that 4.15 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). pd 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: 1809, 1.8 mmol).
- the compound represented by formula (15) was synthesized by protecting one hydroxyl group of 1,4-butanediol with a tetrahydropyranyl (THP) group and reacting the other hydroxyl group with epibromohydrin. .
- THP represents a tetrahydropyranyl group.
- Example 5 In the second reaction, the same operation as in Example 2 was performed except that 5.77 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: 2576, 1.8 mmol).
- a compound represented by formula (16) 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 (16) was obtained.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Example 6 In the second reaction, the same operation as in Example 2 was performed except that 6.02 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: 2604, 1.8 mmol).
- a compound represented by formula (17) was synthesized by the following method.
- a TBS group was introduced to the primary hydroxyl group of 3-allyloxy-1,2-propanediol, and a MOM group was introduced to the secondary hydroxyl group of the obtained compound.
- the TBS group of the resulting compound was removed, and the resulting primary hydroxyl group was reacted with 2-(chloropropoxy)tetrahydro-2H-pyran.
- the double bond of the resulting compound was oxidized.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Example 7 In the second reaction, the same operation as in Example 3 was performed except that 3.89 g of the compound represented by the following formula (18) was used instead of the compound represented by the formula (14).
- G) compound represented by (Ffg 1 and Ffg 2 in formula (G) are represented by formula (GF). mg, ng indicating the average degree of polymerization in Ffg 1 is 2.5, the average in Ffg 2 4.1 g (molecular weight: 2276, 1.8 mmol) was obtained.
- a compound represented by formula (18) was synthesized by reacting 3-buten-1-ol with 2-bromoethoxytetrahydropyran to oxidize the double bond of the resulting compound.
- THP represents a tetrahydropyranyl group.
- Example 8 In the second reaction, the same operation as in Example 3 was performed except that 6.02 g of the compound represented by the following formula (19) was used instead of the compound represented by the formula (14). H) (Ffh 1 and Ffh 2 in formula (H) are represented by formula (HF). mh and nh indicating the average degree of polymerization in Ffh 1 are 2.5, the average in Ffh 2 mh and nh indicating the degree of polymerization are 2.5.) was obtained (molecular weight: 2424, 1.8 mmol).
- a compound represented by formula (19) was synthesized by the following method. Ethylene glycol monoallyl ether was protected with dihydropyran and oxidized to obtain the first compound. The obtained first compound was reacted with the hydroxyl group of 3-buten-1-ol to obtain the second compound. After protecting the secondary hydroxyl group of the obtained second compound with a MOM group, the double bond of the second compound was oxidized. Through the above steps, a compound represented by formula (19) was obtained.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Example 9 In the second reaction, the same operation as in Example 1 was performed except that 4.51 g of the compound represented by the following formula (20) was used instead of the compound represented by the formula (11). I) (Fpi 1 and Fpi 2 in formula (I) are represented by formula (IF). pi indicating the average degree of polymerization in Fpi 1 is 2.5 , and the average degree of polymerization in is 2.5.) was obtained (molecular weight: 1841, 1.8 mmol).
- a compound represented by formula (20) 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 (20) was synthesized by reacting this compound with epibromohydrin.
- Example 10 In the second reaction, the same operation as in Example 1 was performed except that 5.48 g of the compound represented by the following formula (21) was used instead of the compound represented by the formula (11). J) (Fpj 1 and Fpj 2 in formula (J) are represented by formula (JF). pj indicating the average degree of polymerization in Fpj 1 is 2.5, the average degree of polymerization in Fpj 2 is 2.5.) was obtained (molecular weight: 1869, 1.8 mmol).
- a compound represented by formula (21) was synthesized by the following method.
- the secondary hydroxyl group of the compound obtained by reacting the compound represented by formula (11) with allyl alcohol was protected with a MOM group.
- a compound represented by the formula (21) was obtained by oxidizing the double bond of the obtained compound.
- THP represents a tetrahydropyranyl group
- MOM represents a methoxymethyl group
- Example 11 In the second reaction, the same operation as in Example 2 was performed except that 6.99 g of the compound represented by the following formula (22) was used instead of the compound represented by the formula (13).
- K) (Fdk 1 and Fdk 2 in formula (K) are represented by formula (KF).
- a compound represented by formula (22) was synthesized by the following method. Ethylene glycol monoallyl ether was protected with dihydropyran and oxidized to obtain the first compound. The obtained first compound was reacted with the hydroxyl group of 4-penten-1-ol to obtain the second compound. After protecting the secondary hydroxyl group of the obtained second compound with a THP group, the double bond of the second compound was oxidized. Through the above steps, a compound represented by formula (22) was obtained.
- THP represents a tetrahydropyranyl group.
- Example 12 In the second reaction, the same operation as in Example 2 was performed except that 4.76 g of the compound represented by the following formula (23) was used instead of the compound represented by the formula (13).
- L) (Fdl 1 and Fdl 2 in formula (L) are represented by formula (LF). ql indicating the average degree of polymerization in Fdl 1 is 2.5, the average degree of polymerization in Fdl 2 is 2.5.) was obtained (molecular weight: 2544, 1.8 mmol).
- a compound represented by formula (23) 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 (23) was synthesized by reacting this compound with 2-bromoethyloxirane.
- Example 13 In the second reaction, the same operation as in Example 2 was performed except that 3.10 g of the compound represented by the following formula (24) was used instead of the compound represented by the formula (13).
- M) (Fdm 1 and Fdm 2 in formula (M) are represented by formula (MF).
- qm which indicates the average degree of polymerization in Fdm 1 , is 2.5, and the average degree of polymerization in Fdm 2 is 2.5.) was obtained (molecular weight: 2368, 1.8 mmol).
- the compound represented by formula (24) was synthesized by introducing a THP 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.
- Fpn 1 and Ffn 1 in formula (N) are represented by formula (NF).
- pn indicating the average degree of polymerization in Fpn 1 is 2.5
- mn indicating the average degree of polymerization in Ffn 1 , nn represents 2.5 respectively.
- Fpp 1 and Ffp 1 in formula (P) are represented by formula (PF). pp indicating the average degree of polymerization in Fpp 1 is 2.5, mp indicating the average degree of polymerization in Ffp 1 , Each np represents 2.5.
- Fpr 1 and Ffr 1 in formula (R) are represented by formula (RF).
- pr indicating the average degree of polymerization in Fpr 1 is 2.5
- mr indicating the average degree of polymerization in Ffr 1
- Each nr represents 2.5.
- the compound represented by formula (25) 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. It was synthesized by
- THP represents a tetrahydropyranyl group.
- Fps 1 and Ffs 1 in formula (S) are represented by formula (SF). ps indicating the average degree of polymerization in Fps 1 is 2.5, ms indicating the average degree of polymerization in Ffs 1 , Each ns represents 2.5.
- Fpt 1 and Fft 1 in the formula (T) are represented by the formula (TF).
- TF pt indicating the average degree of polymerization in Fpt 1 is 2.5
- mt indicating the average degree of polymerization in Fft 1
- Each nt represents 2.5.
- Fpv 1 and Fpv 2 in formula (V) are represented by formula (VF).
- pv indicating the average degree of polymerization in Fpv 1 is 2.5
- pv indicating the average degree of polymerization in Fpv 2 is 2.5.
- a compound represented by the following formula (AA) 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) p CF 2 CH 2 OH (p indicating the average degree of polymerization in the formula is 2.5) was added to 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 (26) (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 (28) (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 (AA).
- Fpaa 1 and Fpaa 2 in the formula (AA) are represented by the formula (AAF).
- the paa indicating the average degree of polymerization in Fpaa 1 is 2.5
- the paa indicating the average degree of polymerization in Fpaa 2 is 2.5.
- R 1 and R 7 when the compounds of Examples 1 to 13 and Comparative Examples 1 to 14 thus obtained are applied to formula (1) (a in formula (2-1), formula b in (2-2), c in formula (2-3), d in formula (3-1), e in formula (3-2), f in formula (3-3), formula (3-4)), the structure of R 3 and R 5 (g in formula (4)), the structure of R 2 , R 4 and R 6 (h and i in formula (5), Tables 1 and 2 show j in and k) in formula (7).
- the number average molecular weights (Mn) of the compounds of Examples 1 to 13 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.
- 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. It is estimated to be.
- 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 13 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 13 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 had been 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 13 and Comparative Examples 1 to 14 were obtained by the above steps. Further, magnetic recording media (without varnish) of Examples 1 to 13 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 150 B: 150 or more and less than 250 C: 250 or more and less than 350 D: 350 or more and less than 1000 E: 1000 or more
- abrasion resistance test was performed on the varnished magnetic recording media of Examples 1 to 13 and Comparative Examples 1 to 14.
- Abrasion resistance test Using a pin-on-disk type friction and wear tester, an alumina ball with a diameter of 2 mm as a contact is slid on the lubricating layer of the magnetic recording medium at a load of 40 gf and a sliding speed of 0.25 m / sec. The coefficient of friction of the surface of was measured. Then, the sliding time until the coefficient of friction on the surface of the lubricating layer increased sharply was measured.
- the time until the coefficient of friction suddenly increases can be used as an index of the wear resistance of the lubricating layer for the reasons given below. This is because the lubricating layer of the magnetic recording medium wears out as the magnetic recording medium is used, and when the lubricating layer is lost due to wear, the contactor and the protective layer come into direct contact with each other, resulting in a rapid increase in the coefficient of friction. be. It is considered that the time until this coefficient of friction suddenly increases has a correlation with the friction test.
- Examples 1 to 13 and Comparative Examples 1 to 14 were comprehensively evaluated based on the criteria shown below. Table 3 shows the results.
- A All of the results of the corrosion resistance test with varnish, the corrosion resistance test without varnish, and the wear resistance test are A.
- B All of the results of the corrosion resistance test with varnish, the corrosion resistance test without varnish, and the wear resistance test are A or B, and one or more of them are B.
- C One of the results of the corrosion resistance test with varnish and the result of the corrosion resistance test without varnish is B, the other is C, and the result of the wear resistance test is C.
- D All of the results of the corrosion resistance test with varnish, the corrosion resistance test without varnish, and the wear resistance test are C or D, and D is any one or more.
- the result of the corrosion resistance test with varnish, the corrosion resistance test without varnish is D or E
- the wear resistance test result is C.
- E The result of the corrosion resistance test with varnish and the corrosion resistance test without varnish is E, and the result of the abrasion resistance test is D or E.
- Comparative Example 5 is C
- Comparative Examples 2, 4, 6, 9 to 12, and 14 is D
- Comparative Examples 1, 3, 7, 8, and 13. is E
- the comprehensive evaluation of the magnetic recording media of Comparative Examples 1 to 14 having a lubricating layer that does not contain the compound represented by formula (1) is inferior to the magnetic recording media of Examples 1 to 13. Met.
- 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 in R 1 and R 7 in formula (1) contains an ether bond.
- the lubricating layers of the magnetic recording media of Examples 1 to 13 contain a compound in which the distance between the terminal hydroxyl group and the hydroxyl group adjacent to the terminal hydroxyl group is appropriate. For this reason, the intramolecular interaction between the hydroxyl groups is small, and intramolecular aggregation is less likely to occur, and it is presumed that excellent adhesion to the protective layer was obtained and excellent abrasion resistance was exhibited.
- 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. It is from.
- Example 13 the results of the corrosion resistance test were B (with varnish) and B (without varnish), and the result of the abrasion resistance test was B.
- Comparative Example 2 in which R 1 and R 7 are the same as those in Example 13, has the results of the corrosion resistance test of C (with varnish) and C (without varnish), and the results of the wear resistance test of was D.
- Example 3 the results of the corrosion resistance test were B (with varnish) and B (without varnish), and the result of the abrasion resistance test was B.
- Comparative Example 4 in which R1 and R7 are the same as those in Example 3, the results of the corrosion resistance test are D (with varnish) and C (without varnish), and the results of the wear resistance test are was D.
- Example 4 the results of the corrosion resistance test were B (with varnish) and A (without varnish), and the result of the abrasion resistance test was A.
- Comparative Example 5 in which R1 and R7 are the same as those in Example 4, the results of the corrosion resistance test were C (with varnish) and B (without varnish), and the results of the wear resistance test were was C.
- Comparative Examples 11 and 12 the results of the corrosion resistance test were D (with varnish) and D (without varnish), and the result of the abrasion resistance test was D.
- Comparative Example 3 in which R 1 and R 7 are the same as those of Comparative Examples 11 and 12, had corrosion resistance test results of E (with varnish) and E (without varnish). The result of the test was E.
- the compound molecule is not distorted and uniformly adheres to the protective layer. For this reason, it is presumed that the lubricating layer had a high coating rate and good adhesion to the protective layer, resulting in a high corrosion inhibitory effect and wear resistance.
- the lubricant for magnetic recording media containing the fluorine-containing ether compound of the present invention it is possible to form a lubricating layer with high wear resistance and corrosion-inhibiting effect on magnetic recording media.
Abstract
Description
本願は、2021年4月8日に、日本に出願された特願2021-065868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、一般的に潤滑層の厚みを薄くすると、潤滑層の被覆性が低下して、磁気記録媒体の耐摩耗性が低下する傾向がある。このことから、高い耐摩耗性を有する潤滑層が要求されている。
また、従来の磁気記録媒体は、耐腐食性が不十分である場合があった。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、優れた耐摩耗性および磁気記録媒体の腐食抑制効果を有する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、優れた耐摩耗性および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、R6は、同じ構造を有するパーフルオロポリエーテル鎖である;R3およびR5はそれぞれ独立に、1つ以上の水酸基を含む連結基である;R1およびR7はそれぞれ独立に、下記式(2)で表される末端基である。)
-O-CH2-CH(OH)-([D]-CH(OH))s-[E]-CH2OH (2)
(式(2)中、sは0または1である;[D]および[E]はそれぞれ独立に、2~5つのメチレン基(-CH2-)および1つの酸素原子(-O-)の組み合わせからなる鎖状構造、または1~4つのメチレン基(-CH2-)からなる鎖状構造である;ただし、sが0であって[E]が酸素原子を含む場合、[E]に含まれるメチレン基の数は3以上である。)
[2] 前記式(2)で表される末端基が、下記式(2-1)~(2-3)、(3-1)~(3-4)のいずれかで表される末端基である[1]に記載の含フッ素エーテル化合物。
(式(2-1)中のaは1~4の整数である。)
(式(2-2)中のbは2~3の整数である。)
(式(2-3)中のcは1~3の整数である。)
(式(3-1)中のdは1~4の整数である。)
(式(3-2)中のeは1~3の整数である。)
(式(3-3)中のfは1~2の整数である。)
-CF2O-(CF2CF2O)h-(CF2O)i-CF2- (5)
(式(5)中、hおよびiは平均重合度を示し、それぞれ0.1~20を表す。)
-CF2O-(CF2CF2O)j-CF2- (6)
(式(6)中、jは平均重合度を示し、0.1~20を表す。)
-CF2CF2O-(CF2CF2CF2O)k-CF2CF2- (7)
(式(7)中、kは平均重合度を示し、0.1~20を表す。)
-CF2CF2CF2O-(CF2CF2CF2CF2O)l-CF2CF2CF2- (8)
(式(8)中、lは平均重合度を示し、0.1~10を表す。)
-CF(CF3)O-(CF2CF(CF3)O)r-CF(CF3)- (9)
(式(9)中のrは平均重合度を示し、0.1~20を表す。)
[7] 前記式(1)において、R3とR5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、優れた耐摩耗性および磁気記録媒体の腐食抑制効果を有する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、優れた耐摩耗性および耐腐食性を有する。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、優れた耐摩耗性および磁気記録媒体の腐食抑制効果を有する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、1つ以上の水酸基を含む連結基の両端にメチレン基(-CH2-)が結合された連結構造を介して、同じ構造を有する3つのパーフルオロポリエーテル鎖間を結合した鎖状骨格を有し、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つの水酸基を有する式(2)で表される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、優れた耐摩耗性および磁気記録媒体の腐食抑制効果が得られることを確認し、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、R6は、同じ構造を有するパーフルオロポリエーテル鎖である;R3およびR5はそれぞれ独立に、1つ以上の水酸基を含む連結基である;R1およびR7はそれぞれ独立に、下記式(2)で表される末端基である。)
-O-CH2-CH(OH)-([D]-CH(OH))s-[E]-CH2OH (2)
(式(2)中、sは0または1である;[D]および[E]はそれぞれ独立に、2~5つのメチレン基(-CH2-)および1つの酸素原子(-O-)の組み合わせからなる鎖状構造、または1~4つのメチレン基(-CH2-)からなる鎖状構造である;ただし、sが0であって[E]が酸素原子を含む場合、[E]に含まれるメチレン基の数は3以上である。)
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はおよびR7はそれぞれ独立に、式(2)で表される末端基である。式(2)で表される末端基は、2つまたは3つの水酸基を含む。具体的には、式(2)で表される末端基におけるsが0であるときは、2つの水酸基を含み、sが1であるときは、3つの水酸基を含む。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つの水酸基を有するため、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。
これに対し、水酸基の結合している炭素原子同士が、水酸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場合、水酸基の結合していない炭素原子を含む連結基によって、末端水酸基と、末端水酸基に隣接する水酸基の両方が、保護層へ密着できる配向となることができる。このことから、水酸基の結合している炭素原子同士が、水酸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場合、優れた耐摩耗性が得られるものと推定される。
また、末端水酸基が結合する炭素原子と、末端水酸基に隣接する水酸基が結合する炭素原子との間に配置された連結基が、酸素原子(エーテル結合)を含む場合、上記連結基に含まれるメチレン基の数が少なすぎると、エーテル結合に起因する柔軟性によって、末端水酸基と隣接する水酸基との分子内凝集が起こりやすくなる。また、上記連結基に含まれるメチレン基の数が多すぎると、疎水性が高くなりすぎて、保護層との密着性が不十分となる。
式(2)中、sが0であって、[E]が酸素原子を含む場合、[E]に含まれるメチレン基の数は3以上である。すなわち、[E]が酸素原子を含む場合、[E]は3~5つのメチレン基(-CH2-)および1つの酸素原子(-O-)の組み合わせからなる鎖状構造である。
さらに、式(1)において、R1およびR7の少なくとも一方が、式(3-1)~(3-4)のいずれかで表される末端基であることが好ましい。R1およびR7の少なくとも一方が、式(3-1)~(3-4)のいずれかで表される末端基である場合、R1および/またはR7が3つの水酸基を含む含フッ素エーテル化合物となる。その結果、より一層保護層との密着性に優れ、より耐摩耗性の良好な潤滑層を形成できるものとなる。
(式(2-1)中のaは1~4の整数である。)
(式(2-2)中のbは2~3の整数である。)
(式(2-3)中のcは1~3の整数である。)
(式(3-1)中のdは1~4の整数である。)
(式(3-2)中のeは1~3の整数である。)
(式(3-3)中のfは1~2の整数である。)
また、上記式(2-2)および(2-3)で表される末端基において、上記連結基は、4~6原子からなる直鎖状の構造を有する。上記連結基に含まれる原子数が上記範囲内であると、上記連結基が酸素原子を含んでいても、分子の運動性が適切となり、分子内凝集が起こりにくく、保護層との優れた密着性を有する潤滑層が得られる。
また、上記式(3-2)および(3-3)で表される末端基において、上記連結基は、3~5原子からなる直鎖状の構造を有する。上記連結基に含まれる原子数が上記範囲内であると、上記連結基が酸素原子を含んでいても、分子の運動性が適切となり、分子内凝集が起こりにくく、保護層との優れた密着性を有する潤滑層が得られる。
式(1)で表される含フッ素エーテル化合物において、R3およびR5はそれぞれ独立に、1つ以上の水酸基を含む連結基である。R3およびR5に含まれる水酸基は、含フッ素エーテル化合物を含む潤滑層における保護層との密着性を向上させる。R3およびR5に含まれる水酸基の数は、適切な被覆率を維持できるため、それぞれ1~4であることが好ましく、1~2であることがより好ましく、分子の疎水性が適切なものとなることから1であることがさらに好ましい。
また、R3およびR5が式(4)で表される連結基である場合、R3およびR5の両端部に配置された酸素原子は、それぞれ式(4)で表される連結基の両側に配置されるメチレン基(-CH2-)と結合してエーテル結合(-O-)を形成する。この4つのエーテル結合は、式(1)で表される含フッ素エーテル化合物に適度な柔軟性を付与し、R3およびR5の有する水酸基と保護層との親和性を増大させる。
上記式(1)で表される含フッ素エーテル化合物において、R2、R4、R6は同じ構造を有す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、hおよびiは平均重合度を示し、それぞれ0.1~20を表す。)
-CF2O-(CF2CF2O)j-CF2- (6)
(式(6)中、jは平均重合度を示し、0.1~20を表す。)
-CF2CF2O-(CF2CF2CF2O)k-CF2CF2- (7)
(式(7)中、kは平均重合度を示し、0.1~20を表す。)
-CF2CF2CF2O-(CF2CF2CF2CF2O)l-CF2CF2CF2- (8)
(式(8)中、lは平均重合度を示し、0.1~10を表す。)
-CF(CF3)O-(CF2CF(CF3)O)r-CF(CF3)- (9)
(式(9)中のrは平均重合度を示し、0.1~20を表す。)
R2、R4、R6が同じ構造を有するPFPE鎖である場合、PFPE鎖の運動性に起因する分子の歪みが少ない含フッ素エーテル化合物となる。したがって、均一に保護層に密着でき、被覆率の高い潤滑層を形成できる。
なお、式(A)~(M)中のmc、mg、mh、nc、ng、nh、pa、pd、pi、pj、qb、qe、qf、qk、ql、qm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(B)で表される化合物は、R1とR7が式(2-1)で表される末端基であってaが3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(2-2)で表される末端基であってbが2であり、R2とR4とR6が式(5)で表されるPFPE鎖である。
下記式(D)で表される化合物は、R1とR7が式(2-2)で表される末端基であってbが3であり、R2とR4とR6が式(6)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(3-2)で表される末端基であってe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(G)で表される化合物は、R1とR7が式(2-3)で表される末端基であってc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(H)で表される化合物は、R1とR7が式(3-3)で表される末端基であって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(J)で表される化合物は、R1とR7が式(3-1)で表される末端基であってd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(K)で表される化合物は、R1とR7が式(3-3)で表される末端基であってf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(L)で表される化合物は、R1とR7が式(3-4)で表される末端基であり、R2とR4とR6が式(7)で表されるPFPE鎖である。
下記式(M)で表される化合物は、R1とR7が式(2-1)で表される末端基であってaが1であり、R2とR4とR6が式(7)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、paは平均重合度を示し、0.1~20を表す。Fpa1中のpaとFpa2中のpa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を示す。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およびのFfc2中、mc、ncは平均重合度を示し、それぞれ0.1~20を表す。Ffc1中のmc、ncとFfc2中のmc、nc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、pdは平均重合度を示し、0.1~20を表す。Fpd1中のpdとFpd2中のpd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、mg、ngは平均重合度を示し、それぞれ0.1~20を表す。Ffg1中のmg、ngとFfg2中のmg、ngは同じであっても異なっていてもよい。)
(式(H)中のFfh1、Ffh2は式(HF)で表される。Ffh1およびFfh2中、mh、nhは平均重合度を示し、それぞれ0.1~20を表す。Ffh1中のmh、nhとFfh2中のmh、nhは同じであっても異なっていてもよい。)
(式(I)中のFpi1、Fpi2は式(IF)で表される。Fpi1およびFpi2中、piは平均重合度を示し、0.1~20を表す。Fpi1中のpiとFpi2中のpiは同じであっても異なっていてもよい。)
(式(J)中のFpj1、Fpj2は式(JF)で表される。Fpj1およびFpj2中、pjは平均重合度を示し、0.1~20を表す。Fpj1中のpjとFpj2中のpjは同じであっても異なっていてもよい。)
(式(K)中のFdk1、Fdk2は式(KF)で表される。Fdk1およびFdk2中、qkは平均重合度を示し、0.1~20を表す。Fdk1中のqkとFdk2中のqkは同じであっても異なっていてもよい。)
(式(L)中のFdl1、Fdl2は式(LF)で表される。Fdl1およびFdl2中、qlは平均重合度を示し、0.1~20を表す。Fdl1中のqlとFdl2中のqlは同じであっても異なっていてもよい。)
式(1)で表される化合物が、式(B)、(E)~(L)で表される化合物のいずれかであると、特に優れた耐摩耗性および磁気記録媒体の腐食抑制効果を有する潤滑層を形成でき、より好ましい。
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。
まず、式(1)におけるR4に対応するパーフルオロポリエーテル鎖の両末端に、それぞれヒドロキシメチル基(-CH2OH)が配置されたフッ素系化合物を用意する。次いで、前記フッ素系化合物の両末端に配置されたヒドロキシメチル基の水酸基と、R3(=R5)に対応するエポキシ基を有するハロゲン化合物とを反応させる(第一反応)。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両末端に、R3(=R5)に対応するエポキシ基を有する中間体化合物1が得られる。
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。
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、R3の有する水酸基とR5の有する水酸基との距離、R1の有する水酸基とR3の有する水酸基との距離、R5の有する水酸基とR7の有する水酸基との距離が、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の有する水酸基も、保護層上の活性点との結合を、隣接する水酸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の有する水酸基は、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水酸基は、全て保護層上の活性点との結合に関与しない水酸基になりにくい。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水酸基の数が抑制され、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。
式(1)におけるR1およびR7は、それぞれ2つまたは3つの水酸基を含み、水酸基の結合している炭素原子同士が、水酸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おり、水酸基間の距離が適正である。したがって、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、R1およびR7の有する連結基に含まれる炭素原子の疎水性によって、適切な疎水性を有する。
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)pCF2CH2OH(式中の平均重合度を示すp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。この均一の液にエピブロモヒドリン3.45mL(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)pCF2CH2OH(式中の平均重合度を示すp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3.4g(分子量186.25、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7.9g(分子量654、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pは2.5である。)6.5g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pは2.5である。)1.7g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(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HOCH2CF2O(CF2CF2O)pCF2CH2OH(式中の平均重合度を示すp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)pCF2CH2OH(式中の平均重合度を示すp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3.61g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4.4g(分子量2424、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.38~1.81(12H)、3.36~4.35(38H)
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)pCF2CH2OH(式中の平均重合度を示すpは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)m(CF2O)nCF2CH2OH(式中の平均重合度を示すm、n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)pCF2CH2OH(式中の平均重合度を示すpは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)m(CF2O)nCF2CH2OH(式中の平均重合度を示すm、n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3.89g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mc、ncは2.5、Ffc2中の平均重合度を示すmc、ncは2.5である。)を4.1g(分子量2276、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.67(4H)、3.39~4.34(46H)
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4.15g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pdは2.5、Fpd2中の平均重合度を示すpdは2.5である。)を3.3g(分子量1809、1.8mmol)得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.65(8H)、3.42~4.35(46H)
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5.77g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4.6g(分子量2576、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(16)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=3.31~4.41(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6.02g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4.7g(分子量2604、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基を導入し、得られた化合物の2級水酸基にMOM基を導入した。得られた化合物のTBS基を除去し、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(17)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.59(4H)、3.37~4.38(58H)
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3.89g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mg、ngは2.5、Ffg2中の平均重合度を示すmg、ngは2.5である。)を4.1g(分子量2276、1.8mmol)得た。
式(18)で表される化合物は、3-ブテン-1-オールと2-ブロモエトキシテトラヒドロピランとを反応させて得られた化合物の二重結合を酸化させることにより合成した。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.67(4H)、3.38~4.33(46H)
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(14)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6.02g用いたこと以外は、実施例3と同様な操作を行い、上記式(H)で表される化合物(式(H)におけるFfh1、Ffh2は式(HF)で表される。Ffh1中の平均重合度を示すmh、nhは2.5、Ffh2中の平均重合度を示すmh、nhは2.5である。)を4.4g(分子量2424、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、これを酸化させることにより第1化合物を得た。得られた第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化合物を得た。得られた第2化合物の2級水酸基をMOM基で保護してから、第2化合物の二重結合を酸化させた。以上の工程により、式(19)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=3.41~4.36(62H)
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(20)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(I)で表される化合物(式(I)におけるFpi1、Fpi2は式(IF)で表される。Fpi1中の平均重合度を示すpiは2.5、Fpi2中の平均重合度を示すpiは2.5である。)を3.3g(分子量1841、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で、式(20)で表される化合物を合成した。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.58(4H)、3.38~4.34(60H)
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(11)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5.48g用いたこと以外は、実施例1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Fpj1、Fpj2は式(JF)で表される。Fpj1中の平均重合度を示すpjは2.5、Fpj2中の平均重合度を示すpjは2.5である。)を3.4g(分子量1869、1.8mmol)得た。
式(11)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(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(60H)
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(22)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(K)で表される化合物(式(K)におけるFdk1、Fdk2は式(KF)で表される。Fdk1中の平均重合度を示すqkは2.5、Fdk2中の平均重合度を示すqkは2.5である。)を4.7g(分子量2632、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、これを酸化させることにより第1化合物を得た。得られた第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。得られた第2化合物の2級水酸基をTHP基で保護してから、第2化合物の二重結合を酸化させた。以上の工程により、式(22)で表される化合物を得た。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.63(8H)、3.39~4.35(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(23)で表される化合物を4.76g用いたこと以外は、実施例2と同様な操作を行い、上記式(L)で表される化合物(式(L)におけるFdl1、Fdl2は式(LF)で表される。Fdl1中の平均重合度を示すqlは2.5、Fdl2中の平均重合度を示すqlは2.5である。)を4.6g(分子量2544、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(23)で表される化合物を合成した。
1H-NMR(CD3COCD3):δ[ppm]=1.35~1.62(8H)、3.41~4.35(60H)
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(24)で表される化合物を3.10g用いたこと以外は、実施例2と同様な操作を行い、上記式(M)で表される化合物(式(M)におけるFdm1、Fdm2は式(MF)で表される。Fdm1中の平均重合度を示すqmは2.5、Fdm2中の平均重合度を示すqmは2.5である。)を4.3g(分子量2368、1.8mmol)得た。
式(24)で表される化合物は、3-ブテン-1-オールの1級水酸基にTHP基を導入し、得られた化合物の二重結合を酸化させることにより合成した。
1H-NMR(CD3COCD3):δ[ppm]=1.34~1.57(4H)、3.41~4.37(38H)
19F-NMR(acetone-D6):δ[ppm]=-84.0~-83.0(30F)、-86.4(12F)、-124.3(12F)、-130.0~-129.0(15F)
下記式(N)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(O)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]=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(P)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]=3.46~4.18(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(Q)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]=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(R)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。
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(S)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HOCH2CF2O(CF2CF2O)m(CF2O)nCF2CH2OH(式中の平均重合度を示すm、nは2.5である。)で表される化合物の代わりに、HOCH2CF2O(CF2CF2O)pCF2CH2OH(式中の平均重合度を示すp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、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(25)で表される化合物を4.47g用いたこと以外は、実施例3と同様な操作を行い、下記式(S)で表される化合物を3.9g(分子量2143、1.8mmol)得た。
(式(25)中、THPはテトラヒドロピラニル基を表す。)
(式(S)中のFps1、Ffs1は式(SF)で表される。Fps1中の平均重合度を示すpsは2.5であり、Ffs1中の平均重合度を示すms、ns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(T)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。
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(U)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(5F)、-77.7(2F)、-78.6(4F)、-80.3(2F)、-81.3(4F)、-90.0~-88.5(30F)
下記式(V)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]=-78.6(6F)、-81.3(6F)、-90.0~-88.5(30F)
下記式(W)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(15F)、-77.7(6F)、-80.3(6F)、-91.0~-88.5(30F)
下記式(X)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。
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(Y)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。
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(Z)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。
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(AA)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)pCF2CH2OH(式中の平均重合度を示すp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(27)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1~13、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1~13、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1~13、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1~13、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1~13、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1~13、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)
磁気記録媒体を温度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:150未満
B:150以上、250未満
C:250以上、350未満
D:350以上、1000未満
E:1000以上
(耐摩耗性試験)
ピンオンディスク型摩擦摩耗試験機を用い、接触子としての直径2mmのアルミナの球を、荷重40gf、摺動速度0.25m/secで、磁気記録媒体の潤滑層上で摺動させ、潤滑層の表面の摩擦係数を測定した。そして、潤滑層の表面の摩擦係数が急激に増大するまでの摺動時間を測定した。摩擦係数が急激に増大するまでの摺動時間は、各磁気記録媒体の潤滑層について4回ずつ測定し、その平均値(時間)を潤滑剤塗膜の耐摩耗性の指標とした。摩擦係数増大時間の評価基準は、以下のとおりとした。実施例1~13、比較例1~14の化合物を用いた磁気記録媒体の評価結果を表3に示す。
A:650sec以上
B:550sec以上、650sec未満
C:450sec以上、550sec未満
D:350sec以上、450sec未満
E:350sec未満
(総合評価)
A:バーニッシュ有りの耐腐食性試験の結果、バーニッシュ無しの耐腐食性試験の結果、耐摩耗性試験の結果の全てがAである。
B:バーニッシュ有りの耐腐食性試験の結果、バーニッシュ無しの耐腐食性試験の結果、耐摩耗性試験の結果の全てがAまたはBであって、いずれか1つ以上がBである。
C:バーニッシュ有りの耐腐食性試験の結果とバーニッシュ無しの耐腐食性試験の結果のうち一方がBであり、もう一方がCであり、耐摩耗性試験の結果がCである。
D:バーニッシュ有りの耐腐食性試験の結果、バーニッシュ無しの耐腐食性試験の結果、耐摩耗性試験の結果の全てがCまたはDであって、いずれか1つ以上がDである。または、バーニッシュ有りの耐腐食性試験の結果、バーニッシュ無しの耐腐食性試験の結果が、それぞれDまたはEであり、かつ耐摩耗性試験の結果がCである。
E:バーニッシュ有りの耐腐食性試験の結果およびバーニッシュ無しの耐腐食性試験の結果がEであり、かつ耐摩耗性試験の結果がDまたはEである。
また、実施例3は、耐腐食性試験の結果がB(バーニッシュ有り)およびB(バーニッシュ無し)、耐摩耗性試験の結果がBであった。これに対し、R1およびR7が実施例3と同じである比較例4は、耐腐食性試験の結果がD(バーニッシュ有り)およびC(バーニッシュ無し)、耐摩耗性試験の結果がDであった。
また、実施例4は、耐腐食性試験の結果がB(バーニッシュ有り)およびA(バーニッシュ無し)、耐摩耗性試験の結果がAであった。これに対し、R1およびR7が実施例4と同じである比較例5は、耐腐食性試験の結果がC(バーニッシュ有り)およびB(バーニッシュ無し)、耐摩耗性試験の結果がCであった。
式(1)中のR2、R4、R6が同じ構造を有するパーフルオロポリエーテル(PFPE)鎖である化合物では、分子中における各PFPE鎖の運動性が同一となる。これに対し、R2、R4、R6の一部または全部が異なる構造を有するPFPE鎖である化合物では、分子中における各PFPE鎖の運動性の違いによって、分子に歪みが生じる。式(1)中のR2、R4、R6が同じ構造を有するPFPE鎖である化合物を含む潤滑層では、化合物分子の歪みがなく、保護層に均一に密着する。このため、被覆率が高く、保護層との密着性が良好な潤滑層となり、高い腐食抑制効果および耐摩耗性が得られたものと推定される。
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、R6は、同じ構造を有するパーフルオロポリエーテル鎖である;R3およびR5はそれぞれ独立に、1つ以上の水酸基を含む連結基である;R1およびR7はそれぞれ独立に、下記式(2)で表される末端基である。)
-O-CH2-CH(OH)-([D]-CH(OH))s-[E]-CH2OH (2)
(式(2)中、sは0または1である;[D]および[E]はそれぞれ独立に、2~5つのメチレン基(-CH2-)および1つの酸素原子(-O-)の組み合わせからなる鎖状構造、または1~4つのメチレン基(-CH2-)からなる鎖状構造である;ただし、sが0であって[E]が酸素原子を含む場合、[E]に含まれるメチレン基の数は3以上である。) - 前記式(1)において、R1およびR7の少なくとも一方が、前記式(3-1)~(3-4)のいずれかで表される末端基である請求項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、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)h-(CF2O)i-CF2- (5)
(式(5)中、hおよびiは平均重合度を示し、それぞれ0.1~20を表す。)
-CF2O-(CF2CF2O)j-CF2- (6)
(式(6)中、jは平均重合度を示し、0.1~20を表す。)
-CF2CF2O-(CF2CF2CF2O)k-CF2CF2- (7)
(式(7)中、kは平均重合度を示し、0.1~20を表す。)
-CF2CF2CF2O-(CF2CF2CF2CF2O)l-CF2CF2CF2- (8)
(式(8)中、lは平均重合度を示し、0.1~10を表す。)
-CF(CF3)O-(CF2CF(CF3)O)r-CF(CF3)- (9)
(式(9)中のr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、R3とR5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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