Patent ID: 7456238

Claim:
A method of laser welding, comprising the steps of: preparing a first molded article comprising a thermoplastic, the first molded article being transparent to a laser beam used for laser welding; preparing a second molded article comprising a thermoplastic resin and a laser beam absorbing black colorant, the second molded article having a transmission rate ratio (T black resin for laser transmission /T natutal resin ) of 0-0.2 wherein T black resin for laser transmission means the transmission rate of the second molded article and T natural resin means the transmission rate of the thermoplastic resin alone for the laser beam, the laser beam absorbing black colorant comprising a carbon black and a nigrosine dye; positioning the first molded article and the second molded article in contact with each other; and transmitting a laser beam energy focused on the area of contact through the first molded article to the second molded article.