Silane compound containing perfluoro (poly ) ether group

1. A perfluoro(poly)ether group-containing silane compound represented by any of formula (A1) or (B1):

Rf-PFPE-X 1 —SiR a 3   (A1)

Rf-PFPE-X 2 —CR d 3   (B1)

wherein:

PFPE represents, each independently at each occurrence, a group represented by formula:

—(OC 6 F 12 ) a —(OC 5 F 10 ) b —(OC 4 F 8 ) c —(OC 3 F 6 ) d —(OC 2 F 4 ) e —(OCF 2 ) f —

wherein a, b, c, d, e and f are each independently an integer of 0 or more and 50 or less, the sum of a, b, c, d, e and f is 20 to 50, and the occurrence order of respective repeating units in parentheses with a, b, c, d, e or f is not limited in the formula;

Rf represents, each independently at each occurrence, a perfluoroalkyl group having 1 to 16 carbon atoms;

X 1 represents, each independently at each occurrence, an alkylene group having 1 to 3 carbon atoms;

R a represents, each independently at each occurrence, —CH 2 CH 2 —SiR 2 3 ;

R 23 represent a hydroxyl group or a hydrolyzable group;

X 2 represents, each independently at each occurrence, an alkylene group having 1 to 3 carbon atoms;

R d represents, each independently at each occurrence, —CH 2 CH 2 —SiR 73 3 ;

R 73 represents, each independently at each occurrence, a hydroxyl group or a hydrolyzable group.

2. The perfluoro(poly)ether group-containing silane compound according to claim 1 , represented by formula (A1).

3. The perfluoro(poly)ether group-containing silane compound according to claim 1 , represented by formula (B1).

4. The perfluoro(poly)ether group-containing silane compound according to claim 1 , wherein

PFPE is represented, independently at each occurrence, by the following formula (a), (b) or (c):

—(OC 3 F 6 ) d —  (a)

wherein d is an integer of 20 to 50;

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

wherein c and d are each independently an integer of 0 or more and 30 or less;

e and f are each independently an integer of 1 or more and 50 or less;

the sum of c, d, e and f is an integer of 20 or more and 50 or less; and

the occurrence order of respective repeating units in parentheses with a suffix c, d, e or f is not limited in the formula;

—(R 6 —R 7 ) j —  (c)

wherein R 6 is OCF 2 or OC 2 F 4 ;

R 7 is, each independently at each occurrence, a group selected from OC 2 F 4 , OC 3 F 6 , OC 4 F 8 , OC 5 F 10 and OC 6 F 12 ; and

j is an integer of 10 to 25.

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

6. The perfluoro(poly)ether group-containing silane compound according to claim 1 , wherein X 2 is, each independently at each occurrence, —CH 2 —, —CH 2 CH 2 —, or —CH 2 CH 2 CH 2 —.

7. A surface-treating agent comprising the perfluoro(poly)ether group-containing silane compound according to claim 1 .

8. The surface-treating agent according to claim 7 , further comprising one or more other components selected from a fluorine-containing oil, a silicone oil, an alcohol, a catalyst, a transition metal, a halide ion, and a compound containing an atom having an unshared electron pair in a molecular structure.

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

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

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

12. A pellet comprising the surface-treating agent according to claim 7 .

13. An article comprising a base material, and a layer formed from the perfluoro(poly)ether group-containing silane compound according to claim 1 , on the surface of the base material.

14. The article according to claim 13 , wherein the article is an optical member.