Polyester film for capacitors
AssigneeTeijin Limited
InventorsKoji Furuya, Hiroshi Kusume, Makoto Handa
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Abstract
A film which is a biaxially oriented film comprising polyethylene-2,6-naphthalenedicaboxylate as a principal component, having a thermal strain ratio RMD (150) in the machine direction of the film at a temperature of 150° C. is −1.5%≦RMD (150)≦0.0% when the thermal strain ratio RMD (T) in the machine direction of the film at a temperature T° C. based on the length LMD (t) in the machine direction (MD) of the film at a temperature t° C. is defined by RMD(T)={[LMD(T)−LMD(35)]/LMD(35)}×100(%), excellent in insulation characteristics without lowering processing characteristics, especially the characteristics during hot-pressing and suitable as a dielectric for capacitors.
Claims14
A polyester film for capacitors which is a biaxially oriented film comprising polyethylene-2,6-naphthalenedicarboxylate as a principal component and having a thermal strain ratio RMD (150) of the film in the machine direction at a temperature of 150° C. of
- −1.5%≦RMD (150)≦0.0%
- when the thermal strain ratio RMD (T) in the transverse machine direction at a temperature T° C. based on the length LMD (t) in the machine direction (MD) of the film at a temperature t° C. is defined by
- RMD (T)={[LMD (T)−LMD (35)]/LMD (35)}×100(%),
- further wherein the thermal strain ratio RTD (150) in the transverse direction of the film at a temperature of 150° C. is
- −1.0%≦RTD (150)≦0.0%
- when the thermal strain ratio RTD (T) in the transverse direction of the film at a temperature T° C. based on the length LTD (t) in the transverse direction (TD) of the film at a temperature t° C. is defined by
- RTD (T)={[LTD (T)−LTD (35)]/LTD (35)}×100(%);
- and wherein
- the thermal strain ratios RMD (210) and RTD (210) at a temperature of 210° C. are
- −3.5%≦RMD (210)≦0.0%
- −3.5%≦RTD (210)≦0.0%
Dependencies are inferred from the claim text.