SURFACE TREATING AGENT

1 . A surface-treating agent comprising at least one fluoropolyether group-containing compound of the following formula (1) or (2):

R F1 α —X A —R Si β   (1)

R Si γ —X A —R F2 —X A —R Si γ   (2)

wherein

R F1 is each independently at each occurrence R f1 —R F —O q —;

R F2 is —Rf 2 p —R F —O q —;

Rf 1 is each independently at each occurrence a C 1-16 alkyl group optionally substituted with one or more fluorine atoms;

Rf 2 is a C 1-6 alkylene group optionally substituted with one or more fluorine atoms;

R F is each independently at each occurrence a divalent fluoropolyether group;

p is 0 or 1;

q is each independently at each occurrence 0 or 1;

R Si is each independently at each occurrence a monovalent group containing a Si atom to which a hydroxyl group, a hydrolyzable group, a hydrogen atom or a monovalent organic group is bonded;

at least one R Si is a monovalent group containing a Si atom to which a hydroxyl group or a hydrolyzable group is bonded;

X A is each independently a single bond or a di- to decavalent organic group;

α is an integer of 1 to 9;

β is an integer of 1 to 9; and

γ is each independently an integer of 1 to 9, and a chlorine ion,

wherein a chlorine ion concentration in the surface-treating agent is 0.1 ppm by mass or more and 1.0 ppm by mass or less.

2 . The surface-treating agent according to claim 1 , wherein Rf 1 is each independently at each occurrence a C 1-16 perfluoroalkyl group.

3 . The surface-treating agent according to claim 1 , wherein Rf 2 is each independently at each occurrence a C 1-6 perfluoroalkylene group.

4 . The surface-treating agent according to claim 1 , wherein R F is each independently at each occurrence a group of the formula:

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

wherein R Fa is each independently at each occurrence a hydrogen atom, a fluorine atom or a chlorine atom; and

a, b, c, d, e and f are each independently an integer of 0 to 200, the sum of a, b, c, d, e and f is 1 or more, and the occurrence order of the respective repeating units enclosed in parentheses provided with a, b, c, d, e or f is not limited in the formula.

5 . The surface-treating agent according to claim 4 , wherein R Fa is a fluorine atom.

6 . The surface-treating agent according to claim 1 , wherein R F is each independently at each occurrence a group of the following formula (f1), (f2), (f3), (f4) or (f5):

—(OC 3 F 6 ) d —  (f1):

wherein d is an integer of 1 to 200;

—(OC 4 F 8 ) c —(OC 3 F 6 ) d —(OC 2 F 4 ) e —(OCF 2 ) f —  (f2):

wherein c and d are each independently an integer of 0 to 30;

e and f are each independently an integer of 1 to 200;

the sum of c, d, e, and f is an integer of 10 to 200; and

the occurrence order of the respective repeating units enclosed in parentheses accompanied by a subscript c, d, e, or f is not limited in the formula;

—(R 6 -R 7 ) g —  (f3):

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

R 7 is 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 , or is a combination of two or three groups selected from these groups; and

g is an integer of 2 to 100;

—(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 —   (f4):

wherein e is an integer of 1 or more and 200 or less, a, b, c, d, and f are each independently an integer of 0 or more and 200 or less, the sum of a, b, c, d, e, and f is at least 1, and the occurrence order of the respective repeating units enclosed in parentheses provided with a, b, c, d, e or f is not limited in the formula; and

—(OC 6 F 12 ) a —(OCSF 10 ) b —(OC 4 F 8 ) c —(OC 3 F 6 ) d —(OC 2 F 4 ) e —(OCF 2 ) f —   (f5):

wherein f is an integer of 1 or more and 200 or less, a, b, c, d, and e are each independently an integer of 0 or more and 200 or less, the sum of a, b, c, d, e, and f is at least 1, and the occurrence order of the respective repeating units enclosed in parentheses provided with a, b, c, d, e or f is not limited in the formula.

7 . The surface-treating agent according to claim 1 , wherein R Si is a group of the following formula (S1), (S2), (S3) or (S4):

wherein

R 11 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;

R 12 is each independently at each occurrence a hydrogen atom or a monovalent organic group;

n1 is each independently an integer of 0 to 3 for each (SiR 11 n1 R 12 3-n1 ) unit,

X 11 is each independently at each occurrence a single bond or a divalent organic group;

R 13 is each independently at each occurrence a hydrogen atom or a monovalent organic group;

t is each independently at each occurrence an integer of 2 to 10;

R 14 is each independently at each occurrence a hydrogen atom or a halogen atom;

R a1 is each independently at each occurrence —Z 1 —SiR 21 p1 R 22 q1 R 23 r1 ;

Z 1 is each independently at each occurrence an oxygen atom or a divalent organic group;

R 21 is each independently at each occurrence —Z 1′ —SiR 21′ p1′ R 22′ g1′R 23′ r1′ ;

R 22 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;

R 23 is each independently at each occurrence a hydrogen atom or a monovalent organic group;

p1 is each independently at each occurrence an integer of 0 to 3;

q1 is each independently at each occurrence an integer of 0 to 3;

r1 is each independently at each occurrence an integer of 0 to 3;

Z 21′ is each independently at each occurrence an oxygen atom or a divalent organic group;

R 21′ is each independently at each occurrence —Z 1″ —SiR 22″ q1″ R 23″ r1″ ;

R 22′ is each independently at each occurrence a hydroxyl group or a hydrolyzable group;

R 23′ is each independently at each occurrence a hydrogen atom or a monovalent organic group;

p1′ is each independently at each occurrence an integer of 0 to 3;

q1′ is each independently at each occurrence an integer of 0 to 3;

r1′ is each independently at each occurrence an integer of 0 to 3;

Z 1″ is each independently at each occurrence an oxygen atom or a divalent organic group;

R 22 ″ is each independently at each occurrence a hydroxyl group or a hydrolyzable group;

R 23 ″ is each independently at each occurrence a hydrogen atom or a monovalent organic group;

q1″ is each independently at each occurrence an integer of 0 to 3;

r1″ is each independently at each occurrence an integer of 0 to 3;

R b1 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;

R c1 is each independently at each occurrence a hydrogen atom or a monovalent organic group;

k1 is each independently at each occurrence an integer of 0 to 3;

l1 is each independently at each occurrence an integer of 0 to 3;

m1 is each independently at each occurrence an integer of 0 to 3;

R d1 is each independently at each occurrence —Z 2 —CR 31 p2 R 32 q2 R 33 r2 ;

Z 2 is each independently at each occurrence a single bond, an oxygen atom or a divalent organic group;

R 31 is each independently at each occurrence —Z 2′ —CR 32′ q2 ′R 33′ r2′ ;

R 32 is each independently at each occurrence —Z 3 —SiR 34 n2 R 35 3-n2 ;

R 33 is each independently at each occurrence a hydrogen atom, a hydroxyl group, or a monovalent organic group;

p2 is each independently at each occurrence an integer of 0 to 3;

q2 is each independently at each occurrence an integer of 0 to 3;

r2 is each independently at each occurrence an integer of 0 to 3;

Z 2′ is each independently at each occurrence a single bond, an oxygen atom or a divalent organic group;

R 32′ is each independently at each occurrence —Z 3 —SiR 34 n2 R 35 3-n2 ;

R 33′ is each independently at each occurrence a hydrogen atom, a hydroxyl group, or a monovalent organic group;

q2′ is each independently at each occurrence an integer of 0 to 3;

r2′ is each independently at each occurrence an integer of 0 to 3;

Z 3 is each independently at each occurrence a single bond, an oxygen atom or a divalent organic group;

R 34 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;

R 35 is each independently at each occurrence a hydrogen atom or a monovalent organic group;

n2 is each independently at each occurrence an integer of 0 to 3;

R e1 is each independently at each occurrence —Z 3 —SiR 34 n2 R 35 3-n2 ;

R f1 is each independently at each occurrence a hydrogen atom, a hydroxyl group, or a monovalent organic group;

k2 is each independently at each occurrence an integer of 0 to 3;

l2 is each independently at each occurrence an integer of 0 to 3; and

m2 is each independently at each occurrence an integer of 0 to 3.

8 . The surface-treating agent according to claim 1 , wherein each of α, β and γ is 1.

9 . The surface-treating agent according to claim 1 , wherein X A is each independently a trivalent organic group,

α is 1 and β is 2 or a is 2 and β is 1, and

γ is 2.

10 . The surface-treating agent according to claim 1 , wherein the chlorine ion concentration in the surface-treating agent is 0.2 to 0.8 ppm by mass.

11 . The surface-treating agent according to claim 1 , further comprising one or more other component selected from fluorine-containing oil, silicone oil and a catalyst.

12 . The surface-treating agent according to claim 1 , further comprising a solvent.

13 . The surface-treating agent according to claim 1 , which is used as an antifouling coating agent or a water-proof coating agent.

14 . The surface-treating agent according to claim 1 , which is used for vacuum deposition.

15 . A pellet comprising the surface-treating agent according to claim 1 .

16 . 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 1 .

17 . The article according to claim 16 , which is an optical member.