Polyester film having improved adhesion properties
AssigneeHoechst Aktiengesellschaft
InventorsHartmut Hensel, Peter Dinter, Theo Grosse-Kreul, John D. Gribbin
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Abstract
The biaxially stretch oriented, corona-treated polyester film, in particular polyethylene terephthalate film, is suitable as a base film for magnetic coatings. It exhibits the following features: at least one of its two surfaces exhibits a surface tension of at least 43 mN/m without an adhesion promoter having been added; the modulus of elasticity in the machine direction and/or transverse direction is greater than 5800 N/mm.sup.2 ; and the refractive index perpendicular to the film plane is less than or equal to 1.4900.
Claims7
A biaxially stretch oriented polyester film, suitable as a base film for magnetic coatings comprising:
- a biaxially oriented polyester film having 2 surfaces, at least one of said two surfaces having a surface tension of at least 43 mN/m without an adhesion promoter having been added;
- a modulus of elasticity in the machine direction greater than 5800 N/mm.sup.2;
- and
- a refractive index in the direction of the thickness of the film of less than or equal to 1.4900, wherein said at least one surface of the film has been subjected to a corona discharge treatment after thermosetting.
A magnetic tape comprising:
- a) a biaxially oriented polyester film having two surfaces, with at least one of said surfaces having tension of at least 43 mN/m, without the use of an adhesion promoter:
- a modulus of elasticity in the machine direction greater than 5800 N/mm.sup.2 ;
- and a refractive index perpendicular to the film plane of less than or equal to 1.4900;
- and
- b) a magnetic coating applied to said at least one surface, said coating applied in an effective amount to enable magnetic recordings.
Dependencies are inferred from the claim text.