Silane compound containing perfluoro(poly)ether group

1. A perfluoro(poly)ether group containing silane compound of formula (1a):

Rf-PFPE)-X—C(—Y—SiR 5 n R 6 3-n ) 3   (1a)

wherein:

Rf is each independently at each occurrence an alkyl group having 1-16 carbon atoms which may be substituted by one or more fluorine atoms;

PFPE is each independently at each occurrence a group of the formula:

—(OC 4 F 8 ) a —(OC 3 F 6 ) b —(OC 2 F 4 ) c —(OCF 2 ) d —

wherein a, b, c and d are each independently an integer of 0-200, the sum of a, b, c and d is 5 or more, and the occurrence order of the respective repeating units in parentheses with the subscript a, b, c or d is not limited in the formula;

PFPE binds to Rf via oxygen atom at its left end and binds to X via carbon atom at its right end in formula (1a);

X is each independently the following divalent organic group;

a C 1-20 alkylene group,

—R 31 —X c —R 31 —, or

wherein R 31 is each independently a single bond, or —(CH 2 ) s′ — (wherein s′ is an integer of 1-20), with the proviso that at least one of R 31 is not a single bond;

X c is

—O—,

—CONR 34 —, or

—O—CONR 34 —,

wherein R 34 is each independently at each occurrence a hydrogen atom or a C 1-6 alkyl group;

Y is each independently at each occurrence a C 1-6 alkylene group, —(CH 2 ) g′ —O—(CH 2 ) h′ — (wherein g′ is an integer of 0-6, and h′ is an integer of 0-6), or -phenylene-(CH 2 ) i′ — (wherein i′ is an integer of 0-6);

R 5 is each independently at each occurrence a hydroxyl group or —OR, —OCOR, —O—N═C(R) 2 , —N(R) 2 , —NHR, halogen (wherein R is a substituted or non-substituted alkyl group having 1-4 carbon atoms);

R 6 is each independently at each occurrence a hydrogen atom or a lower alkyl group;

n is an integer of 1-3 independently per unit —Y—SiR 5 n R 6 3-n .

2. The perfluoro(poly)ether group containing silane compound according to claim 1 wherein Rf is a perfluoroalkyl group having 1-16 carbon atoms.

3. The perfluoro(poly)ether group containing silane compound according to claim 1 wherein PFPE is a group of any of the following formulae (i) to (iv):

—(OCF 2 CF 2 CF 2 ) b —  (i)

wherein b is an integer of 1-200;

—(OCF(CF 3 )CF 2 ) b —  (ii)

wherein b is an integer of 1-200;

—(OCF 2 CF 2 CF 2 CF 2 ) a —(OCF 2 CF 2 CF 2 ) b —(OCF 2 CF 2 ) c —(OCF 2 ) d —  (iii)

wherein a and b are each independently an integer of 0-30, c and d are each independently an integer of 1-200, the sum of a, b, c and d is 5 or more, and the occurrence order of the respective repeating units in parentheses with the subscript a, b, c or d is not limited in the formula;

or

—(OC 2 F 4 —R 8 ) n″ —  (iv)

wherein R 8 is a group selected from OC 2 F 4 , OC 3 F 6 and OC 4 F 8 , or a combination of 2 or 3 groups independently selected from these groups, and the sum of OC 2 F 4 , OC 3 F 6 and OC 4 F 8 is 5 or more; and

n″ is an integer of 2-100.

4. The perfluoro(poly)ether group containing silane compound according to claim 1 wherein X is each independently selected from the group consisting of:

—CH 2 O(CH 2 ) 2 —,

—CH 2 O(CH 2 ) 3 —,

—CH 2 O(CH 2 ) 6 —,

—(CH 2 ) 2 —,

—(CH 2 ) 3 —,

—(CH 2 ) 4 —,

—(CH 2 ) 5 —,

—(CH 2 ) 6 —,

—CONH—(CH 2 ) 3 —,

—CON(CH 3 )—(CH 2 ) 3 —,

—CONH—(CH 2 ) 6 —,

—CON(CH 3 )—(CH 2 ) 6 —,

—CH 2 O—CONH—(CH 2 ) 3 —, and

—CH 2 O—CONH—(CH 2 ) 6 —.

5. The perfluoro(poly)ether group containing silane compound according to claim 1 wherein an average molecular weight of the Rf-PFPE moiety is 500-30,000.

6. The perfluoro(poly)ether group containing silane compound according to claim 1 having an average molecular weight of 2,000-32,000.

7. A surface-treating agent comprising at least one perfluoro(poly)ether group containing silane compound of the formula (1a) according to claim 1 .

8. The surface-treating agent according to claim 7 further comprising one or more components selected form a fluorine-containing oil, a silicone oil and a catalyst.

9. The surface-treating agent according to claim 8 wherein the fluorine-containing oil is one or more compounds of the formula (3):

R 21 —(OC 4 F 8 ) a′ —(OC 3 F 6 ) b′ —(OC 2 F 4 ) c′ —(OCF 2 ) d′ —R 22   (3)

wherein:

R 21 is an alkyl group having 1-16 carbon atoms which may be substituted by one or more fluorine atoms;

R 22 is an alkyl group having 1-16 carbon atoms which may be substituted by one or more fluorine atoms, a fluorine atom or a hydrogen atom; and

a′, b′, c′ and d′ are the repeating number of each of four repeating units of perfluoro(poly)ether which constitutes a main backbone of the polymer, and are each independently an integer of 0 or more and 300 or less, the sum of a′, b′, c′ and d′ is 1 or more, and the occurrence order of the respective repeating units in parentheses with the subscript a′, b′, c′ and d′ is not limited in the formula.

10. The surface-treating agent according to claim 8 wherein the fluorine-containing oil is one or more compounds of the formula (3a) or (3b):

R 21 —(OCF 2 CF 2 CF 2 ) b″ —R 22   (3a)

R 21 —(OCF 2 CF 2 CF 2 CF 2 ) a″ —(OCF 2 CF 2 CF 2 ) b″ —(OCF 2 CF 2 ) c″ —(OCF 2 ) d″ —R 22   (3b)

wherein:

R 21 is an alkyl group having 1-16 carbon atoms which may be substituted by one or more fluorine atoms;

R 22 is an alkyl group having 1-16 carbon atoms which may be substituted by one or more fluorine atoms, a fluorine atom or a hydrogen atom;

in the formula (3a), b″ is an integer of 1 or more and 100 or less;

in the formula (3b), a″ and b″ are each independently an integer of 0 or more and 30 or less, and c″ and d″ are each independently an integer of 1 or more and 300 or less; and

the occurrence order of the respective repeating units in parentheses with the subscript a″, b″, c″ or d″ is not limited in the formula.

11. The surface-treating agent according to claim 10 comprising at least one compound of the formula (3b).

12. The surface-treating agent according to claim 10 wherein a mass ratio of the perfluoro(poly)ether group containing silane compound of the formula (1a) and the compound of the formula (3b) is 4:1-1:4.

13. The surface-treating agent according to claim 10 wherein the compound of the formula (3a) has a number average molecular weight of 2,000-8,000.

14. The surface-treating agent according to claim 10 wherein the compound of the formula (3b) has a number average molecular weight of 2,000-30,000.

15. The surface-treating agent according to claim 10 wherein the compound of the formula (3b) has a number average molecular weight of 8,000-30,000.

16. The surface-treating agent according to claim 7 further comprising a solvent.

17. The surface-treating agent according to claim 7 which is used as an antifouling-coating agent or a water-proof coating agent.

18. The surface-treating agent according to claim 7 for vacuum deposition.

19. A pellet containing the surface-treating agent according to claim 7 .

20. An article comprising a base material and a layer which is formed on a surface of the base material from the surface treating agent according to claim 7 .

21. An article comprising a base material and a layer which is formed on a surface of the base material from the compound according to claim 1 .

22. The article according to claim 21 wherein the article is an optical member.

23. The article according to claim 21 wherein the article is a display.