Ink-repellent member and ink jet head

An ink jet head having an ink ejection surface comprising an underlying portion containing at least one of a silicon oxide and a tantalum oxide, the underlying portion having a fluorine compound bonded to a surface thereof,

• wherein, when a static contact angle and a receding contact angle of the surface after the ink jet head is subjected to the following immersion treatment are represented by θ and θr, respectively, the θ is 100° or more and θ−θr is less than 20°:
• (Immersion Treatment)
• (1) a test piece including the surface is cut out of the ink jet head, is placed in a sealable container containing an aqueous solution having a pH of 11, and is immersed in the aqueous solution so that the test piece is entirely immersed therein;
• and
• (2) the test piece is maintained at 70° C. for 170 hours under a sealed state after the immersion in (1).

An ink-repellent member comprising an underlying portion having a surface and containing an inorganic oxide,

• wherein, when a static contact angle and a receding contact angle of the surface after the ink-repellent member is subjected to the following immersion treatment are represented by θ and θr, respectively, the θ is 100° or more and θ−θr is less than 20°:
• (Immersion Treatment)
• (1) a test piece including the surface is cut out of the ink-repellent member, is placed in a sealable container containing an aqueous solution having a pH of 11, and is immersed in the aqueous solution so that the test piece is entirely immersed therein;
• and
• (2) the test piece is maintained at 70° C. for 170 hours under a sealed state after the immersion in (1).