Surface treatment agent

A surface-treating agent comprising

• (1) at least one perfluoro(poly)ether group containing silane compound of any of the formulae (A1), (A2), (B1), (B2), (C1), (C2), (D1) and (D2):
• wherein:
• PFPE is each independently at each occurrence a group of the formula:
• —(OC4F8)a—(OC3F6)b—(OC2F4)c—(OCF2)d—
• wherein a, b, c and d are each independently an integer of 0-200, the sum of a, b, c and d is at least one, 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;
• 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;
• R1 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;
• R2 is each independently at each occurrence a hydrogen atom or an alkyl group having 1-22 carbon atoms;
• R11 is each independently at each occurrence a hydrogen atom or a halogen atom;
• R12 is each independently at each occurrence a hydrogen atom or a lower alkyl group;
• n1 is, independently per a unit (—SiR1n1R23- n 1), an integer of 0-3;
• at least one n1 is an integer of 1-3 in the formulae (A1), (A2), (B1) and (B2);
• X1 is each independently a single bond or a 2-10 valent organic group;
• X2 is each independently at each occurrence a single bond or a divalent organic group;
• t is each independently at each occurrence an integer of 1-10;
• α is each independently an integer of 1-9;
• α′ is each independently an integer of 1-9;
• X5 is each independently a single bond or a 2-10 valent organic group;
• β is each independently an integer of 1-9;
• β′ is each independently an integer of 1-9;
• X7 is each independently a single bond or a 2-10 valent organic group;
• γ is each independently an integer of 1-9;
• γ′ is each independently an integer of 1-9;
• Ra is each independently at each occurrence —Z1—SiR71p1R72q1R73r1;
• Z1 is each independently at each occurrence an oxygen atom or a divalent organic group;
• R71 is each independently at each occurrence Ra′;
• Ra′ has the same definition as that of Ra;
• in Ra, the number of Si atoms which are straightly linked via the Z1 group is up to five;
• R72 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;
• R73 is each independently at each occurrence a hydrogen atom or a lower alkyl group;
• p1 is each independently at each occurrence an integer of 0-3;
• q1 is each independently at each occurrence an integer of 0-3;
• r1 is each independently at each occurrence an integer of 0-3;
• at least one q1 is an integer of 1-3 in the formula (C1) and (C2);
• Rb is each independently at each occurrence a hydroxyl group or a hydrolyzable group;
• Rc is each independently at each occurrence a hydrogen atom or a lower alkyl group;
• k1 is each independently at each occurrence an integer of 1-3;
• l1 is each independently at each occurrence an integer of 0-2;
• m1 is each independently at each occurrence an integer of 0-2;
• the sum of k1, l1 and m1 is 3 in each unit in parentheses with the subscript γ;
• X9 is each independently a single bond or a 2-10 valent organic group;
• δ is each independently an integer of 1-9;
• δ′ is each independently an integer of 1-9;
• Rd is each independently at each occurrence —Z2—CR81p2R82q2R83r2;
• Z2 is each independently at each occurrence an oxygen atom or a divalent organic group;
• R81 is each independently at each occurrence Rd′;
• Rd′ has the same definition as that of Rd;
• in Rd, the number of C atoms which are straightly linked via the Z2 group is up to five;
• R82 is each independently at each occurrence —Y—SiR85n2R863-n2;
• Y is each independently at each occurrence a divalent organic group;
• R85 is each independently at each occurrence a hydroxyl group or a hydrolyzable group;
• R86 is each independently at each occurrence a hydrogen atom or a lower alkyl group;
• n2 is an integer of 1-3 independently per unit (—Y—SiR85n2R863-n2);
• in formulae (D1) and (D2), at least one n2 is an integer of 1-3;
• R83 is each independently at each occurrence a hydrogen atom or a lower alkyl group;
• p2 is each independently at each occurrence an integer of 0-3;
• q2 is each independently at each occurrence an integer of 0-3;
• r2 is each independently at each occurrence an integer of 0-3;
• Re is each independently at each occurrence —Y—SiR85n2R86n2;
• Rf is each independently at each occurrence a hydrogen atom or a lower alkyl group;
• k2 is each independently at each occurrence an integer of 0-3;
• l2 is each independently at each occurrence an integer of 0-3;
• and
• m2 is each independently at each occurrence an integer of 0-3;
• in formulae (D1) and (D2), at least one q2 is 2 or 3, or at least one l2 is 2 or 3;
• and
• (2) a fluorine containing oil of the general formula (0):
• Rf1-PFPE′-Rf2 (O)
• wherein:
• Rf1 is each independently at each occurrence a C1-16 alkyl group which may be substituted by one or more fluorine atoms;
• Rf2 is a C1-16 alkyl group which may be substituted by one or more fluorine atoms, a fluorine atom or a hydrogen atom;
• PFPE′ is —(OC4F8)a′—(OC3F6)b′(OC2F4)c′—(OCF2)d′—;
• a′, b′, c′ and d′ are each independently an integer of 0 or more and 300 or less, the sum of a′, b′, c′ and d′ is at least 1, 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,
• wherein a content of the fluorine containing oil having a molecular weight of 2.0 or more times higher than the number average molecular weight of the fluorine-containing oil among the fluorine containing oil of the formula (O) is 10 mol % or less;
• and
• wherein a number average molecular weight of the fluorine containing oil is 1,500 or more and 30,000 or less.