Abstract: Provided is a process for fusion-bonding plastic parts with the aid of laser radiation of a wavelength outside the visible region, wherein a bonding region of a plastic part to be bonded comprises at least one material which is transparent in the visible region of the electromagnetic spectrum, is substantially colorless and absorbs the laser radiation, wherein the material comprises at least one nonionic compound that is resistant to the laser radiation, has a thermal stability of at least 300° C. and is selected from polycyclic organic compounds, doped tin oxides and hexaborides MB6 of lanthanides and alkaline earth metals M. Also provided is a preparation suitable for producing fusion-bonded plastic parts with the aid of laser radiation whose wavelength is outside the visible region, the preparation comprising: a thermoplastic matrix polymer suitable for forming the plastics parts; at least one of said material; optional UV stabilizers; and optional additives.

Abstract: Disclosed is a method for welding together plastic parts with the aid of laser radiation having a wavelength outside the visible range. According to the inventive method, the joining zone of one of the plastic parts that are to be joined together is provided with a substantially colorless material that is transparent in the visible range of the electromagnetic spectrum while absorbing the laser radiation. The inventive method is characterized in that at least one non-ionic, laser radiation-resistant compound that has a minimum thermal resistance of 300° C. and is selected among the group comprising the polycyclic organic compounds, doped tin oxides, and hexaborides MB6 of lanthanide metals and alkaline earth metals M is used as the laser radiation-absorbent material.