Heat-seal patch.

A patch is decoration made away from the garment and applied afterwards, and what makes one heat-sealable is a film of hot-melt adhesive laminated to its back. Twill USA sells that film by the yard on a paper or mylar carrier and splits it by thickness: 1.5 mil is a temporary tack that holds an applique while it is embroidered, 5 mil is the permanent bond that makes a no-sew patch. Laser cutting is the other half of the category, because the beam melts the edge of a polyester twill as it cuts and the patch stops fraying without a merrowed border, which is why the same converting line runs laser cutters up to 54 inches wide. Stahls' offers emblems as heat applied or pressure sensitive, and that choice is really a question about laundry, worth asking before the order rather than after. The bond is only as good as the surface under it: a water-repellent shell or a heavy finish gives the adhesive nothing to key into, and the patch comes back off in the customer's machine.