I bought some funky iron on patches for my kids bookbags (so they can identify them easily) but they will not stick on. Their bookbags are that shiny smooth polyester fabric. I have tried ironing them (they peel off easily), using Gorilla Glue, fabric glue, super glue but none of them work and I have had to sew them on which defeats the point. Anyone got any tips on getting them to stick (so that other kids cannot easily rip them off)?