Aromatic compounds bearing hydroxyl-substituted (per)fluoropolyether chains

1. A compound (L) comprising at least one moiety (A*) wherein moiety (A*) is selected from benzene, biphenyl and naphthalene, and wherein:

at least two carbon atoms of moiety (A*) are substituted with a fluoropolyoxyalkene chain (R f ), each chain (R f ) comprising:

a) a fluorocarbon segment having ether linkages in the main chain and

b) at least one hydroxyl group,

each chain (R f ) being bound to an sp 2 carbon atom of said moiety (A*) through bridging group (B) comprising at least one heteroatom directly bound to said sp 2 carbon atom, and wherein:

in moiety (A*), all carbon atoms which do not bear a chain (R f ) are substituted with a fluorine atom.

2. A compound (L) according to claim 1 wherein chain (R f ) comprises repeating units R°, said repeating units being selected from:

(i) —CFXO—, wherein X is F or CF 3 ,

(ii) —CFXCFXO—, wherein X, equal or different at each occurrence, is F or CF 3 , with the provision that at least one of X is F,

(iii) —CF 2 CF 2 CW 2 O—, wherein each of W, equal or different from each other, are F, Cl, H,

(iv) —CF 2 CF 2 CF 2 CF 2 O—,

(v) (CF 2 ) j —CFZ—O— wherein j is an integer from 0 to 3 and Z is a group of general formula —OR f ′T 3 , wherein R f ′ is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being selected from: —CFXO—, —CF 2 CFXO—, —CF 2 CF 2 CF 2 O—, —CF 2 CF 2 CF 2 CF 2 O—, with each of each of X being independently F or CF 3 and T 3 being a C 1 -C 3 perfluoroalkyl group.

3. A compound (L) according to claim 2 , wherein chain (R f ) complies with formula (R f -I) here below:

—(CFX 1 O) g1 (CFX 2 CFX 3 O) g2 (CF 2 CF 2 CF 2 O) g3 (CF 2 CF 2 CF 2 CF 2 O) g4 —  (R f -I)

wherein:

X 1 , X 2 , X 3 equal or different from each other and at each occurrence are independently —F, —CF 3 ;

g1, g2, g3, and g4, equal or different from each other, are independently integers≥0, such that g1+g2+g3+g4 is in the range from 2 to 300; should at least two of g1, g2, g3 and g4 be different from zero, the different recurring units are generally statistically distributed along the chain.

4. A compound (L) according to claim 1 , wherein the compound is of formula:

wherein

A* is selected from benzene, biphenyl and naphthalene;

B is a bridging group (B) selected from a C 1 -C 20 divalent alkylene group comprising at least one sulfur or oxygen atom directly bound to an sp 2 carbon atom of moiety (A*), said group being optionally fluorinated and optionally containing one or more hydroxyl groups and from a group forming with moiety (A*) a condensed ring (R) comprising aromatic moiety (A*) and a non-aromatic cyclic moiety comprising two heteroatoms, each heteroatom being directly bound to an sp 2 carbon atom of moiety (A*);

R f is a divalent fluoropolyoxyalkene chain (R f ) wherein chain (R f ) comprises repeating units R°, said repeating units being chosen from:

(i) —CFXO—, wherein X is F or CF 3 ,

(ii) —CFXCFXO—, wherein X, equal or different at each occurrence, is F or CF 3 , with the provision that at least one of X is —F,

(iii) —CF 2 CF 2 CW 2 O—, wherein each of W, equal or different from each other, are F, Cl, H,

(iv) —CF 2 CF 2 CF 2 CF 2 O—,

(v) —(CF 2 ) j —CFZ—O— wherein j is an integer from 0 to 3 and Z is a group of general formula —OR f ′T 3 , wherein R f ′ is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being selected from:

—CFXO—, —CF 2 CFXO—, —CF 2 CF 2 CF 2 O—, —CF 2 CF 2 CF 2 CF 2 O—, with each of each of X being independently F or CF 3 and T 3 being a C 1 -C 3 perfluoroalkyl group;

Y is a hydrocarbon group, optionally fluorinated, which comprises at least one hydroxyl group;

G is a fluorine atom;

x is an integer of at least 2;

y is an integer of z−x, wherein z is the number of carbon atoms of moiety (A*), when bridging group (B) is a divalent alkylene group as defined above or z−2x, when bridging group (B) forms a condensed ring (R) as defined above, with the proviso that, when moiety (A*) is a polycyclic or polycondensed aromatic moiety, the number of bridging carbon atoms is to be detracted from z.

5. A compound (L) according to claim 4 of formula (L-1*) below:

wherein x is an integer of at least 2, and n is 6−x.

6. A compound (L) according to claim 5 wherein x is an integer ranging from 2 to 4.

7. A compound (L) according to claim 6 which is selected from:

a compound (L-1*a), wherein B is —OCH 2 CF 2 O— and Y is —CF 2 CH 2 OH;

a compound (L-1*b), wherein B is —OCH 2 CH(OH)CH 2 OCH 2 CF 2 O— and Y is —CF 2 CH 2 OCH 2 CHOHCH 2 OH;

a compound (L-1*c), wherein B is —OCH 2 CF 2 O— and Y is —CF 2 CH 2 OCH 2 CHOHCH 2 OH;

a compound (L-1*d) wherein B is —OCH 2 CH(OH)CH 2 OCH 2 CF 2 O— and Y is —CF 2 CH 2 OH;

and wherein:

chain (R f ) complies with formula (R f -III) below:

—O(CF 2 CF 2 O) a1 (CF 2 O) a2 —  (R f -III)

wherein:

a1, and a2 are integers>0 such that the number average molecular weight is between 400 and 10,000, with the ratio a2/a1 being comprised between 0.1 and 10, and

x ranges from 2 to 4 and n is 6−x.

8. A process for the manufacture of a compound (L) according to claim 1 , said process comprising the reaction of a perfluorinated monocyclic, polycyclic or polycondensed aromatic compound (A) with a (per)fluoropolyether (PFPE) polyol [PFPE (P pol )].

9. A lubricant composition for magnetic recording media (MRM), said composition comprising one or more compounds (L) as defined in claim 1 in admixture with further ingredients.

10. A method of lubricating a magnetic recording media (MRM), said method comprising using one or more compounds (L) as defined in claim 1 .

11. A compound (L) according to claim 3 , wherein g1+g2+g3+g4 is in the range from 2 to 100.

12. A compound (L) according to claim 7 , wherein a1, and a2 are integers>0 such that the number average molecular weight is between 400 and 5,000 and wherein the ratio a2/a1 is between 0.2 and 5.