Surface treatment agent

A surface-treating agent comprising:

• (I) a compound represented by the following formula (I-1) or formula (I-2):
• wherein:
• R1 is a monovalent organic group containing a polyether chain and is represented by:
• wherein (OR2)a is a polyether chain;
• R1′ is a divalent organic group containing a polyether chain;
• the polyether chain is a chain represented by formula:
• wherein m14 is each independently an integer of 1 to 200;
• X1 is independently a silane-containing reactive crosslinkable group;
• and
• X2 independently represents a monovalent group;
• and
• (II) a perfluoropolyether group-containing silane compound having an OCF2 unit represented by the following formula (C1) and a perfluoropolyether group-containing silane compound having an OCF2 unit represented by the following formula (C2):
• wherein
• Rf is each independently an alkyl group having 1 to 16 carbon atoms optionally substituted with one or more fluorine atoms;
• PFPE is a group represented by:
• wherein e1 and f1 are each independently an integer of 1 or more and 200 or less, and the occurrence order of the respective repeating units in parenthesis with e1 or f1, is not limited in the formula;
• X107 is each independently —(CH2)s′—O—(CH2)t′—, or —CF2—(CH2)s′—O—(CH2)t′;
• s′ is an integer of 1 to 20;
• t′ is an integer of 1 to 20;
• γ is each independently an integer of 1 to 9;
• γ′ is an integer of 1 to 9;
• Ra3, at each occurrence, is each independently —Z3—SiR71pR72qR73r;
• Z3, at each occurrence, is each independently an oxygen atom or a divalent organic group;
• R71, at each occurrence, is each independently Ra′;
• Ra′ has the same meaning as Ra3;
• the number of Si atoms linearly linked via a Z3 group in Ra3 is at most 5;
• R72, at each occurrence, is each independently a hydroxyl group or a hydrolyzable group;
• R73, at each occurrence, is each independently a hydrogen atom or a lower alkyl group;
• p, at each occurrence, is each independently an integer of 0 to 3;
• q, at each occurrence, is each independently an integer of 0 to 3;
• r, at each occurrence, is each independently an integer of 0 to 3;
• provided that the sum of p, q and r with respect to (—Z3—SiR71pR72qR73r) is 3 and at least one R72 is present in formulae (C1) and (C2);
• wherein the perfluoropolyether group-containing silane compound having an OCF2 unit is a compound different from the compound represented by the formula (I-1) or formula (I-2), and
• the weight ratio of (I) to (II) is 2:8 to 9:1.