Biaxially oriented polyester film for backsheet of solar batteries
View Patent ↗The present invention provides a biaxially oriented polyester film for a backsheet of solar batteries which exhibits a good hydrolysis resistance and a low haze. The present invention relates to a biaxially oriented polyester film for a backsheet of solar batteries, comprising titanium in an amount of not more than 20 ppm in terms of a titanium atom, phosphorus in an amount of not more than 70 ppm in terms of a phosphorus atom, and antimony in an amount of not more than 10 ppm in terms of an antimony atom; and having a carboxyl end group content of not more than 26 equivalents/t and an intrinsic viscosity of 0.65 to 0.90.
1. A biaxially oriented polyester film for a backsheet of solar batteries, consisting essentially of
a polyester obtained by a step consisting of subjecting an aromatic dicarboxylic acid and an aliphatic glycol to polycondensation reaction,
titanium in an amount of not more than 20 ppm in terms of a titanium atom,
phosphorus in an amount of not more than 70 ppm in terms of a phosphorus atom, and
antimony in an amount of not more than 10 ppm in terms of an antimony atom; and
having a carboxyl end group content of not more than 26 equivalents/t and an intrinsic viscosity of 0.65 to 0.90 dL/g.
2. The biaxial oriented polyester film according to claim 1 , wherein the intrinsic viscosity is not less than 0.68 dL/g.
3. The biaxial oriented polyester film according to claim 1 having the carboxyl end group content of not more than 24 equivalents/t.
4. The biaxial oriented polyester film according to claim 1 having the carboxyl end group content of not less than 5 equivalents/t.
5. The biaxial oriented polyester film according to claim 1 comprising titanium in an amount of not more than 15 ppm in terms of a titanium atom.
6. The biaxial oriented polyester film according to claim 1 comprising titanium in an amount of not more than 12 ppm in terms of a titanium atom.
7. The biaxial oriented polyester film according to claim 1 comprising titanium in an amount of not more than 9 ppm in terms of a titanium atom.
8. The biaxial oriented polyester film according to claim 1 comprising titanium in phosphorus in an amount of not more than 50 ppm in terms of a phosphorus atom.
9. The biaxial oriented polyester film according to claim 1 comprising titanium in phosphorus in an amount of not more than 30 ppm in terms of a phosphorus atom.
10. The biaxial oriented polyester film according to claim 1 comprising antimony in an amount of not more than 8 ppm in terms of an antimony atom.
11. The biaxial oriented polyester film according to claim 1 comprising antimony in an amount of not more than 5 ppm in terms of an antimony atom.