Fluorine-containing ether compound, lubricant for magnetic recording medium, and magnetic recording medium
Provided is a fluorine-containing ether compound that can be suitably used as a material for a lubricant for a magnetic recording medium, capable of forming a lubricant layer having excellent chemical substance resistance and wear resistance even when the thickness is small. A fluorine-containing ether compound represented by the following formula (1): R 1 —R 2 —CH 2 —R 3 —CH 2 —R 4 —R 5 (1) In the formula (1), R 3 is a perfluoropolyether chain. R 2 and R 4 are divalent linkage groups having a polar group, and may be the same or different. R 1 and R 5 are terminal groups bonded to R 2 or R 4 , which may be the same or different, and at least one of R 1 and R 5 is an organic group having 1 to 8 carbon atoms wherein one or more hydrogen atoms of the organic group is substituted with a cyano group.
1. A fluorine-containing ether compound represented by the following formula (1),
R 1 —R 2 —CH 2 —R 3 —CH 2 —R 4 —R 5 (1)
wherein in the formula (1), R 3 is a perfluoropolyether chain; R 2 and R 4 are divalent linkage groups represented by the following formula (2-1) and may be the same or different; R 1 and R 5 are terminal groups bonded to R 2 or R 4 and may be the same or different; and at least one of R 1 and R 5 is an organic group having 1 to 8 carbon atoms wherein one or more hydrogen atoms of the organic group is substituted with a cyano group,
—(X—CH 2 CH(OH)CH 2 ) a —X— (2-1)
wherein in the formula (2-1), a represents an integer of 1 to 3, X represents an oxygen atom or CH 2 , and two X may be the same or different.
2. The fluorine-containing ether compound according to claim 1 , wherein the organic group is a phenyl group or an alkyl group having 1 to 5 carbon atoms.
3. The fluorine-containing ether compound according to claim 1 , wherein a in the formula (2-1) is 1 or 2, and each X is an oxygen atom.
4. The fluorinated ether compound according to claim 1 , wherein R 3 in the formula (1) is any one of the following formulas (3) to (5),
—CF 2 O—(CF 2 CF 2 O) c —(CF 2 O) d —CF 2 — (3)
wherein c and d in the formula (3) represent an average degree of polymerization and each represents 0 to 20, and c or d is 0.1 or more;
—CF(CF 3 )—(OCF(CF 3 )CF 2 ) e —OCF(CF 3 )— (4)
wherein in formula (4), e represents an average degree of polymerization and represents 0.1 to 20; and
—CF 2 CF 2 —(OCF 2 CF 2 CF 2 ) f —OCF 2 CF 2 — (5)
wherein in the formula (5) f represents an average degree of polymerization and represents 0.1 to 20.
5. The fluorine-containing ether compound according to claim 1 , wherein R 1 and R 5 in the formula (1) are the same, and R 2 and R 4 are the same.
6. The fluorine-containing ether compound according to claim 5 , wherein R 1 and R 5 in the formula (1) are alkyl groups having 1 to 5 carbon atoms wherein the alkyl groups are substituted with at least one cyano group.
7. The fluorine-containing ether compound according to claim 1 , wherein R 1 and R 5 in the formula (1) are different, and one of R 1 and R 5 is a phenyl group substituted with at least one cyano group or an alkyl group having 1 to 5 carbon atoms substituted with at least one cyano group, and the other of R 1 and R 5 is an organic group having at least one selected from the group consisting of an aromatic ring, a heterocyclic ring, an alkenyl group, an alkynyl group and a hydroxy group.
8. The fluorine-containing ether compound according to claim 1 , wherein a number average molecular weight is in the range of 500 to 10,000.
9. A lubricant for magnetic recording media, comprising the fluorine-containing ether compound according to claim 1 .
10. A magnetic recording medium in which at least a magnetic layer, a protective layer, and a lubricant layer are sequentially provided on a substrate, wherein the lubricant layer contains the fluorine-containing ether compound according to claim 1 .
11. The magnetic recording medium according to claim 10 , wherein an average film thickness of the lubricant layer is 0.5 nm to 2 nm.