Polyester is also available with surface coatings and/or treatments to make them more receptive to ink coating (screen printing). It is possible that some of these would be suitable but they would have to be tested first.
We get most of our polyester from Autotype: http://www.macdermidautotype.com/aut...ope/Industrial
This page shows a range of surface coatings for various applications. We purchase it through another company who either slit it to the widths we require or (more often) sheet it out to our required size.