In recent years, due to increasing environmental awareness, in the fields of building materials, automotive parts, cellular phones, electric appliances and the like, there is an increased demand for solvent-less coating and plating alternatives and introduction of a decoration method using a film has been more advanced.
Under such circumstances, several proposals have been made as biaxially-stretched polyester films for forming. For example, there are proposed a polyester film forming in which a specific forming stress at normal temperature is defined (see, for example, Patent Document 1) and a polyester film for forming in which the forming stress, thermal shrinkage and planar orientation degree at 25° C. and 100° C. are defined (see, for example, Patent Document 2).
In addition, there is proposed an unstretched polyester film for forming which shows excellent formability at low temperatures and utilizes an amorphous polyester (see, for example, Patent Document 3) and, as a film for transfer foil which can be used for printing process and coating process, a film in which a polyolefin film is laminated onto at least one side of an unstretched polyester film is proposed (see, for example, Patent Document 4). Moreover, there is proposed a forming release film as a film comprising a cyclic olefin-based resin (Patent Document 5) and, as a cyclic olefin-based film for cosmetic sheet, a film in which polyethylene is blended with a cyclic olefin is also proposed (see, for example, Patent Document 6).