Patent Number: 054223830
Section: abstract

A laser beam absorbing resin composition is disclosed which includes 100 parts by weight of a resin, and 1-100 parts by weight of composite particles having an average particle diameter of 0.1-50 .mu.m and each including a particulate, laser beam absorbing inorganic substance, and a colorant physically bonded directly to the inorganic substance and capable of discoloring upon being heated at a temperature of 250.degree. C. or more, the weight ratio of the colorant to the inorganic substance being in the range of 1:99 to 50:50. By irradiating a shaped, hardened body of the above composition with a laser beam, the colorant is thermally decomposed, so that the color of the irradiated surface is changed and becomes discriminative from that of non-irradiated surface.