Disclosed are polyester shrink films comprising a voiding agent dispersed within a continuous polyester phase. The voiding agent comprises at least one first polymer and at least one second polymer, in which the polymer components have selected physical properties such as glass transition temperature, melting point, tensile modulus, surface tension, and melt viscosity. The resulting shrink films have high opacity, a low coefficient of friction, lower density, low shrink force, and good printability. The films are useful for sleeve label and other shrink film applications, and their lower density allows them to be readily separated from soft drink bottles, food containers and the like during recycling operations. Also disclosed is a process for separating a void-containing polyester from a mixture of polymers.