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

1. A fluorine-containing ether compound represented by the following formula (1),

R 1 —R 2 —CH 2 —R 3 —CH 2 —R 4   (1)

(in the formula (1), R 3 is a perfluoropolyether chain; R 1 is represented by the following formula (2), a in the formula (2) is an integer of 2 or 3, in the formula (2), R 5 and R 6 are the same or different substituents, and R 5 and R 6 may form a ring structure together with a nitrogen atom; R 2 is represented by the following formula (3), and b in the formula (3) is an integer of 1 to 3; R 4 is a terminal group having two or three polar groups, in which individual polar groups bond to different carbon atoms and the carbon atoms to which the polar groups bond are bonded to each other through a linking group having a carbon atom to which the polar groups do not bond),

2. The fluorine-containing ether compound according to claim 1 ,

wherein R 5 and R 6 are each independently a saturated aliphatic group having one to four carbon atoms or R 5 and R 6 form a five to seven-membered ring together with a nitrogen atom.

3. The fluorine-containing ether compound according to claim 1 ,

wherein R 5 R 6 N— in the formula (2) is a dimethylamino group or a diethylamino group.

4. The fluorine-containing ether compound according to claim 1 ,

wherein R 5 R 6 N— in the formula (2) is any one group selected from a pyrrolidine group, a piperidine group, a morpholine group, and a hexamethyleneimine group.

5. The fluorine-containing ether compound according to claim 1 ,

wherein the R 3 is any of the following formulae (4) to (6),

—CF 2 O—(CF 2 CF 2 O) c —(CF 2 O) d —CF 2 —  (4)

(c and d in the formula (4) indicate average degrees of polymerization and each represents 0 to 30; here, there is no case where c and d become 0 at the same time),

—CF(CF 3 )—(OCF(CF 3 )CF 2 ) e —OCF(CF 3 )—  (5)

(e in the formula (5) indicates an average degree of polymerization and represents 0.1 to 30),

—CF 2 CF 2 O—(CF 2 CF 2 CF 2 O) f —CF 2 CF 2 —  (6)

(f in the formula (6) indicates an average degree of polymerization and represents 0.1 to 30).

6. The fluorine-containing ether compound according to any claim 1

wherein the polar group in the R 4 is a hydroxyl group.

7. The fluorine-containing ether compound according to claim 1 ,

wherein the R 4 is a terminal group of any of the following formulae (7) to (10),

(in the formula (7), g represents an integer of 1 or 2, and h represents an integer of 1 to 5),

(in the formula (8), i represents an integer of 2 to 5),

(in the formula (9), j represents an integer of 1 to 5), and

(in the formula (10), k represents an integer of 1 or 2, and l represents an integer of 1 or 2).

8. The fluorine-containing ether compound according to claim 1 ,

wherein a number-average molecular weight thereof is within a range of 500 to 10000.

9. The fluorine-containing ether compound according to claim 1 ,

wherein the compound represented by the formula (1) is any of compounds represented by the following formulae (A) to (D), (N) and (O),

(in the formula (A), ma and na indicate average degrees of polymerization, ma represents 1 to 30, and na represents 0 to 30),

(in the formula (B), mb and nb indicate average degrees of polymerization, mb represents 1 to 30, and nb represents 0 to 30),

(in the formula (C), mc and nc indicate average degrees of polymerization, mc represents 1 to 30, and nc represents 0 to 30),

(in the formula (D), md and nd indicate average degrees of polymerization, md represents 1 to 30, and nd represents 0 to 30),

(in the formula (N), mn and nn indicate average degrees of polymerization, mn represents 1 to 30, and nn represents 0 to 30), and

(in the formula (O), mo and no indicate average degrees of polymerization, mo represents 1 to 30, and no represents 0 to 30).

10. A lubricant for a magnetic recording medium, comprising:

the fluorine-containing ether compound according to claim 1 .

11. A magnetic recording medium comprising at least:

a magnetic layer;

a protective layer; and

a lubricating layer sequentially provided on a substrate,

wherein the lubricating layer contains the fluorine-containing ether compound according to claim 1 .

12. The magnetic recording medium according to claim 11 ,

wherein the lubricating layer has an average film thickness of 0.5 nm to 2 nm.