Laser-transmissible composition and method of laser welding

A method for laser welding comprising:

• preparing a dynamic crosslinking polyolefin thermoplastic elastomer in the presence of a metallocene catalyst including, as a main component, an ethylene-alpha-olefin random copolymer elastomer with a ratio of ethylene to alpha-olefin between 55:45 to 80:20 by weight, the dynamic crosslinking polyolefin thermoplastic elastomer having a melting point ranging from 160 to 210 degrees Centigrade;
• dynamically crosslinking the dynamic crosslinking polyolefin thermoplastic elastomer with a crosslinking agent;
• providing a laser energy-transmissible molded workpiece comprising a laser energy-transmissible composition comprising the dynamic crosslinking polyolefin thermoplastic elastomer and a dye salt capable of transmitting laser energy having a wavelength of 800 to 1200 nm, wherein the dye salt comprises an anion of an acid dye and a cation of an organic amine and the dye salt is selected from the group consisting of a monoazo dye salt, a disazo dye salt, an anthraquinone dye salt, an anthrapyridone dye salt, and a triphenylmethane dye salt;
• providing a laser energy-absorptive molded workpiece comprising a composition comprising a thermoplastic polypropylene resin and a laser energy-absorbent including carbon black;
• placing the laser energy-transmissible molded workpiece
• irradiating a laser towards the laser energy-transmissible molded workpiece to weld the laser energy-transmissible molded workpiece to the laser energy-absorptive molded workpiece.