To provide a coloring agent for black coloring laser marking which is capable of presenting clear black marking on the surface of a resin.
The coloring agent for black coloring laser marking is provided for presenting the marking in irradiation with laser light of a molded article constituted of a polymer that changes itself in color with reception of the laser light. The coloring agent is constituted of a reaction product obtained by making polyvalent carboxylic acid and polyvalent alcohol into ester or of a modified material obtained by modifying at least some of terminal groups of the reaction product to alkyl groups, and the heat resistance temperature set on the occasion when a temperature at 20% weight reduction is made that temperature in a thermogravimetric analysis (TGA) is 230-590°C.
NUMAKURA TORU
TSUCHIMOCHI YUICHI
KAWAKAMI KAZUMI
Next Patent: RUBBER COATING DEVICE FOR CORD