COATED FILM
According to the present invention, there is provide a coated film having excellent properties which can be highly prevented from suffering from deposition of oligomers from a surface of the film when exposed to a high temperature condition, and is free from occurrence of disadvantages due to the oligomers (ester cyclic trimer) upon storage, use or processing of the film, etc. The present invention relates to a coated film comprising a single-layer polyester film having an ester cyclic trimer content of not more than 0.7% by weight or a multilayer polyester film comprising a polyester surface layer having an ester cyclic trimer content of not more than 0.7% by weight, and a coating layer formed on at least one surface of the single-layer polyester film or multilayer polyester film, the coating layer being formed from a coating solution comprising a polyvalent aldehyde-based compound.
1 . A coated film comprising a single-layer polyester film having an ester cyclic trimer content of not more than 0.7% by weight or a multilayer polyester film comprising a polyester surface layer having an ester cyclic trimer content of not more than 0.7% by weight, and a coating layer formed on at least one surface of the single-layer polyester film or multilayer polyester film, the coating layer being formed from a coating solution comprising a polyvalent aldehyde-based compound.
2 . The coated film according to claim 1 , wherein a thickness of the single-layer polyester film or multilayer polyester film is 10 to 300 μm, and a thickness of the surface layer of the multilayer polyester film is not less than 1.5 μm.
3 . The coated film according to claim 1 , wherein the polyester film has a multilayer structure having three layers constituted of two kinds of materials.
4 . The coated film according to claim 1 , wherein the polyvalent aldehyde-based compound is an acetalization reaction product obtained from a polyvalent aldehyde compound and a polyhydric alcohol.
5 . The coated film according to claim 1 , wherein a content of the polyvalent aldehyde-based compound in the coating solution is in the range of 1 to 50% by weight based on a total weight of whole non-volatile components in the coating solution.
6 . The coated film according to claim 1 , wherein the coating solution further comprises at least one compound selected from the group consisting of an ammonium group-containing polymer, a polyvinyl alcohol and a crosslinking agent.
7 . The coated film according to claim 6 , wherein a content of each of the ammonium group-containing polymer, the polyvinyl alcohol and the crosslinking agent in the coating solution is in the range of 5 to 80% by weight based on a total weight of whole non-volatile components in the coating solution.