The present invention provides a method of cross-linking a thermoplastic polyurethane (TPU) for making a directly laser engravable flexographic printing article. The printing article can be a flat printing plate or a continuous in-the-round printing sleeve. TPUs can be compounded in an extruder using various cross-linking and laser sensitive additives. The compounded TPU is extruded on a flat carrier or a round sleeve, cross-linked during or after extrusion using thermal energy or UV radiation. The extruded and cross-linked TPU is ground or machined to the dimension required for the printing process and is ready for laser engraving. The printing element is laser engraved using infrared lasers using computer generated graphics. After engraving a simple wipe-down is all that is required before the plate or sleeve is used on a flexographic printing press. Other binders such as thermoplastic polyester elastomer and thermoplastic polyamide elastomer can also be used.