Fluorine-containing ether compound, method for producing same, lubricant for magnetic recording media, and magnetic recording media

1 . A fluorine-containing ether compound represented by Formula (1),

R 1 —CH 2 —R 2a —CH 2 —R 3a —CH 2 —R 2b —CH—R 3b —CH 2 —R 2c —CH 2 —R 3c —CH 2 —R 2a —CH 2 —R 4   (1)

(in Formula (1), R 2a , R 2b , R 2c , and R 2d are each a perfluoropolyether chain; R 3a , R 3b , and R 3c are each a divalent linking group having one or more polar groups; at least one of R 3a , R 3b , and R 3c is represented by Formula (3); and R1 and R4 are each a terminal group having 1 to 50 carbon atoms and one or more polar groups, and may be the same as or different from each other)

—OCH 2 CH(OH)CH 2 O—  (3).

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

wherein at least one of R 1 and R 4 in Formula (1) is a terminal group of any of Formulae (2-1) to (2-4),

(in Formula (2-1), p represents an integer of 1 to 3, and q represents an integer of 1 to 3)

(in Formula (2-2), r represents an integer of 0 to 2, and s represents an integer of 1 to 3)

(in Formula (2-3), t represents an integer of 1 to 3, u represents an integer of 0 to 2, and v represents an integer of 1 to 3)

(in Formula (2-4), l represents an integer of 1 to 3, m represents an integer of 1 to 4, and n represents an integer of 1 to 4; and X represents an organic group including a double bond or a triple bond).

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

wherein all of the polar groups contained in R 3a , R 3b , and R 3c in Formula (1) are hydroxy groups.

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

wherein a total number of hydroxy groups contained in R 1 and hydroxy groups contained in R 4 in Formula (1) is 2 to 6.

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

wherein all of R 3a , R 3b , and R 3c in Formula (1) are represented by Formula (3).

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

wherein one or two of R 3a , R 3b , and R 3c in Formula (1) are divalent linking groups that are not Formula (3), and the divalent linking groups that are not Formula (3) are each independently a divalent linking group having one to three hydroxy groups and 4 to 9 carbon atoms.

7 . The fluorine-containing ether compound according to claim 6 ,

wherein the divalent linking groups that are not Formula (3) are each independently a linking group represented by any of Formulae (3-1) to (3-4) and arranged between two perfluoropolyether chains selected from R 2a , R 2b , R 2c , and R 2d ,

(in Formula (3-1), d represents 2 or 3)

(in Formula (3-2), e represents an integer of 2 to 4; in Formula (3-2), an oxygen atom on a left side is bonded to the perfluoropolyether chain having a side chain containing R 1 at the end in Formula (1) through the methylene group, and an oxygen atom on a right side is bonded to the perfluoropolyether chain having a side chain containing R 4 at the end in Formula (1) through the methylene group)

(in Formula (3-3), f represents an integer of 2 to 4; in Formula (3-3), an oxygen atom on a left side is bonded to the perfluoropolyether chain having a side chain containing R 1 at the end in Formula (1) through the methylene group, and an oxygen atom on a right side is bonded to the perfluoropolyether chain having a side chain containing R 4 at the end in Formula (1) through the methylene group) (in Formula (3-4), g represents an integer of 0 to 4).

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

wherein in Formula (1), R 2a and R 2d are the same as each other, R 2b and R 2c are the same as each other, atoms included in R 3a and atoms included in R 3c are symmetrically arranged with respect to R 3b , and R 1 and R 4 are the same as each other,

R 3b is represented by any of the Formula (3) and the Formulae (3-1) to (3-4),

the fluorine-containing ether compound comprises:

a compound in which R 3a and R 3c are each represented by Formula (3):

a compound in which R 3a and R 3c are each represented by Formula (3-1) and the values of d in Formula (3-1) are the same; a compound in which one of R 3a and R 3c is represented by Formula (3-2), and the other is represented by Formula (3-3), and e in Formula (3-2) and f in Formula (3-3) have the same value; or

a compound in which R 3a and R 3c are each represented by Formula (3-4) and the values of g in Formula (3-4) are the same.

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

wherein R 2a , R 2b , R 2c , and R 2d in Formula (1) are entirely the same as each other, all of R 3a , R 3b , and R 3c are represented by Formula (3), and R 1 and R 4 are the same as each other.

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

wherein R 2a , R 2b , R 2c , and R 2d in Formula (1) are each independently any one selected from perfluoropolyether chains represented by Formulae (4-1) to (4-4),

—CF 2 —(OCF 2 CF 2 ) h —(OCF 2 ) i —OCF 2 —  (4-1)

(in Formula (4-1), h and i each indicate an average degree of polymerization, h represents 1 to 20, and i represents 0 to 20)

−CF 2 CF 2 −(OCF 2 CF 2 CF 2 ) j —OCF 2 CF 2 —  (4-2)

(in Formula (4-2), j indicates an average degree of polymerization and represents 1 to 15)

—CF 2 CF 2 CF 2 —(OCF 2 CF 2 CF 2 CF 2 ) k —OCF 2 CF 2 CF 2 —  (4-3)

(in Formula (4-3), k indicates an average degree of polymerization and represents 1 to 10)

—(CF 2 ) w7 —O—(CF 2 CF 2 CF 2 O) w8 —(CF 2 CF 2 O) w9 —(CF 2 ) w10 —  (4-4)

(in Formula (4-4), w8 and w9 each indicate an average degree of polymerization and each independently represent 1 to 20; and w7 and w10 are each an average value indicating the number of CF 2 's and each independently represent 1 or 2).

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

wherein the fluorine-containing ether compound has a number-average molecular weight in a range of 500 to 10,000.

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

the fluorine-containing ether compound according to claim 1 .

13 . A magnetic recording medium comprising, in the following order, on a substrate, at least:

a magnetic layer;

a protective layer; and

a lubricating layer,

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

14 . The magnetic recording medium according to claim 13 ,

wherein an average film thickness of the lubricating layer is 0.5 nm to 2.0 nm.

15 . A method for producing the fluorine-containing ether compound according to claim 1 , the method comprising:

an end part producing step of producing an intermediate compound 1a having a group corresponding to R 1 —CH 2 —R 2a —CH 2 — in Formula (1) and an intermediate compound 1b having a group corresponding to —CH 2 —R 2d —CH 2 —R 4 in Formula (1);

a linked structure producing step of producing an intermediate compound 3 having a group corresponding to —R 3a —CH 2 —R 2b —CH 2 —R 3b —CH 2 —R 2c —CH 2 —R 3c — in Formula (1); and

a compound structure producing step including an R 1 -side reaction step of reacting an R 3a -side end part of the intermediate compound 3 with the intermediate compound 1a, and an R 4 -side reaction step of reacting an R 3c -side end part of the intermediate compound 3 with the intermediate compound 1b,

wherein the linked structure producing step includes: a linking end part producing step of producing an intermediate compound 2a having a group corresponding to —R 3a —CH 2 —R 2b —CH 2 — in Formula (1) and an intermediate compound 2b having a group corresponding to —CH 2 —R 2c —CH 2 —R 3c — in Formula (1); an R 2b -side reaction step of reacting an R 2b -side end part of a compound having a group corresponding to R 3b in Formula (1) with the intermediate compound 2a; and an R 2c -side reaction step of reacting an R 2c -side end part of the compound having a group corresponding to R 3b with the intermediate compound 2b, and

in the end part producing step, the intermediate compound 1a is produced by reacting R 2a and the epoxy compound having a group corresponding to R 1 in Formula (1), and the intermediate compound 1b is produced by reacting R 2d and the epoxy compound having a group corresponding to R 4 in Formula (1),

in the linked structure producing step, the intermediate compound 2a is produced by reacting R 2b and a compound having a group corresponding to R 3a in Formula (1), and the intermediate compound 2b is produced by reacting R 2c and a compound having a group corresponding to R 3c in Formula (1), and

the compound structure producing step comprises:

a step of reacting the intermediate compound 1a and the epoxy group corresponding to R 3a present at the terminal of the intermediate compound 3:

a step of reacting the intermediate compound 1b and the epoxy group corresponding to R 3c present at the terminal of the intermediate compound 3.

16 . The method for producing a fluorine-containing ether compound according to claim 15 ,

wherein in Formula (1), R 2a and R 2d are the same as each other, R 2b and R 2c are the same as each other, atoms included in R 3a and atoms included in R 3c are symmetrically arranged with respect to R 3b , and R 1 and R 4 are the same as each other,

in the end part producing step, the intermediate compound 1a and the intermediate compound 1b are produced at the same time,

in the linking end part producing step, the intermediate compound 2a and the intermediate compound 2b are produced at the same time, and the R 2b -side reaction step and the R 2c -side reaction step are performed at the same time, and

in the compound structure producing step, the R 1 -side reaction step and the R 4 -side reaction step are performed at the same time.