Patent ID: 7153384

Claim:
A method of laser welding characterized in that a contact portion of a laser ray transmitting material comprising a laser ray transmitting colored thermoplastic resin composition and a laser ray absorbing material is welded by an irradiating laser ray so that the laser ray passes through the laser ray transmitting material and is absorbed in the laser ray absorbing material with the laser ray transmitting material and the laser ray absorbing material in contact with each other, said laser ray transmitting colored thermoplastic resin composition containing a dis-azo salt forming dye which consists of an anionic component from a dis-azo acid dye and an organic ammonium component, said acid dye being represented by Formula (1) below, R 1 —N═N-E-N═N-R 2 (1) in Formula (1), E represents a group represented by Formula (2), (3) or (4) below, each of R 1 and R 2 independently represents an aryl group not having or having a substituent, or a pyrazolone group not having or having a substituent, one or two or more of E, R 1 and R 2 have a sulfonic acid group as a substituent, in Formula (2), each of R 3 and R 4 independently represents a hydrogen atom, an alkyl group, or a sulfonic acid group, in Formula (3), each of R 5 and R 6 independently represents a hydrogen atom or a sulfonic acid group, in Formula 4, R 15 represents a sulfonic acid group.