| 摘要 |
PROBLEM TO BE SOLVED: To realize a laminated polyester film having high hiding properties and excellent flexibility and whiting properties by a method wherein the apparent density of a film, which is prepared by laminating a white polyester layer onto at least one side of a light screen agent-containing polyester layer, is set to lie within a predetermined range. SOLUTION: This polyester film is a composite film prepared by laminating a white polyester layer onto at least one side of a light screen agent-containing polyester layer. As the light screen agent to be added in this polyester layer, a black-based or colored dye, a pigment made of a black-based or colored metal oxide, composite oxide, sulfide, nitride or the like, a carbon black or the like is employed. This white polyester layer is prepared by including a white dye, fine white particles or the like in a layer made of a polyester under the condition that an infinite number of fine bubbles are developed in the layer so as to scatter the light by the bubbles in order to produced a white and opaque layer. In addition, the apparent density of the polyester film is set to 0.5-1.3 g/cm<2> . |
