Substrate having a treatment surface

摘要

For obtaining a substrate on the surface of which a water repellent film is firmly bonded through an undercoating film, and which shows a low critical inclination angle, superior durability, and high density, a water repellent and/or oil repellent film layer is formed by using a liquid for undercoating treatment. The liquid for undercoating treatment is obtained by dissolving and reacting a material having chlorosilyl radicle radicle in molecular form therein and is dissolved into an alcohol group solvent, so that a surface roughness (Ra) of less than 0.5 nm is obtained, thereby achieving high durability and a low critical inclination angle.