| abstract |
A porous polyester film containing a polyester resin as a main starting material is provided. By optimizing the melt viscosity of a void-forming agent to be added, the ratio of the number of voids to film thickness can be set to 0.20 void/μm or above. As a result a lightweight polyester film can be provided, which has a high strength, superior processability and high reflectivity to visible light. This film is suitable as a material for various reflectors. |