Abstract: The laser-transmissive welding label of the present invention is a resin label which comprises at least a resin layer and is affixable to a resin shaped article by a laser welding, wherein the resin layer has a light-scattering property, and the transmittance of the resin layer relative to a laser beam having an oscillation wavelength within the range of 740 to 1100 nm is not less than 20%, and the total light transmittance of the resin layer relative to a visible light (in accordance with ASTM D1003) is not more than 50%. The resin layer may comprise a thermoplastic resin which may have a compatibility with a resin for the resin shaped article. The label may be able to mask the resin shaped article, or may be colored with a coloring agent. A shaped composite article (e.g., a toner cartridge) may be formed by bonding the label to the resin shaped article with use of the laser welding.

Abstract: In a method for improving bonding strength between a first resin article and a second resin article, the method comprises using a compatibilizer for both a first thermoplastic resin and a second thermoplastic resin, wherein the first resin article is formed from a first resin composition comprising a first thermoplastic resin, and the second resin article is formed from a second thermoplastic resin or a second resin composition comprising a second thermoplastic resin, and at least the first resin composition out of the first and the second resin compositions comprises the compatibilizer, wherein the first and the second resin articles are welded to each other by laser irradiation to form a composite article.