Surface treatment agent

A surface treatment agent comprising:

• (A) a water- and oil-repellent polymer having a repeating unit derived from at least one water- and oil-repellent monomer selected from
• (A1) a fluorine-containing monomer and
• (A2) a fluorine-free monomer having a hydrocarbon group having 7 to 40 carbon atoms,
• where the amount of the water- and oil-repellent monomer is 30 to 100 wt % based on the amount of the water- and oil-repellent polymer;
• (B) a silicone polymer of the formula:
• (R53)3Si—O—[—Si(R51)2—O—]a—[—Si(R51)(R52)—O—]b—Si(R53)3
• wherein each R51 independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms,
• each R52 independently represents a saturated hydrocarbon group having 23 to 40 carbon atoms,
• each R53 independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a saturated hydrocarbon group having 23 to 40 carbon atoms,
• a represents an integer of 0 or more, b represents an integer of 1 or more, and (a+b) is 10 to 200;
• and
• (C) a liquid medium.