Polyester film recovery method, recycled polyester product, recovery device, and functional layer removal agent

A polyester film recovery method comprising:

• removing a functional layer through cleaning a laminated polyester film including a polyester film having the functional layer on a surface of the polyester film, with a cleaning agent;
• and
• recovering the polyester film, from which the functional layer has been removed
• wherein the functional layer comprises at least one selected from the group consisting of a hard coat layer, a pressure-sensitive adhesive layer, a release layer, a decorative layer, a light shielding layer, an ultraviolet ray shielding layer, an adhesion promoting layer, an antistatic layer, a refractive index regulating layer, and an oligomer blocking layer,
• the functional layer and the polyester film are directly in contact to each other before the removing,
• the cleaning agent comprises a compatibilizing agent (c), and
• the compatibilizing agent (c) comprises at least one selected from the group consisting of an aromatic sulfonate salt and a hydroxy group-containing amine compound.