PURPOSE: To obtain polyester film having excellent adhesiveness and almost no aging change by applying special treatment to polyester sheets.
CONSTITUTION: Sheets formed in polyester copolymer are treated with low temperature plasma. On the surface of the treated sheet, more than 30 oxygen atoms exist against a single carbon atoms of the ester group according to measurements by ESCA analysis. When this treated sheet is later elongated or elongated and thermally treated into film, the number of oxygen atoms is reduced to the range of 2.2 to 3.0 pieces, but the adhesiveness of film is significantly enhanced. Also almost no aging change of the film is recognized. Thus the surface itself of the film becomes a thin reformed layer. This reformed layer of the film can be provided on one side, both sides or any part of the film excepting edges on film surface according to usage.
KAWAKAMI KENICHI
KOBAYASHI HIROAKI
