Patent ID: 6310118
Filing Date: 2001-10-30
Classification: C01P,C09C,C09D

Abstract:
A colorant composition comprising at least a powder dispersed in a dispersion medium, said powder comprising a base particle coated with a multilayered film comprising layers differing from each other in refractive index and having a color due to light interference among the layers constituting the multilayered film, said powder having an interference reflection peak in the visible light region and an interference reflection peak outside the visible light region, wherein the thickness of each layer satisfies the following equation (1):N.times.d=m.times..lambda./4 (1)wherein N represents a complex refractive index; d represents a basic film thickness; m represents an integer (natural number); .lambda. represents a wavelength at which an interference reflection peak or interference transmission peak appears; and N is defined by the following equation (2):N=n+i.kappa. (2)wherein n represents a refractive index of each unit coating layer; i represents a complex number; and .kappa. represents an extinction coefficient, the actual thicknesses of the unit coating layers being corrected to account for phase shift caused by the extinction coefficient .kappa. of the refractive index, the phase shift occurring at film interfaces, and the peak shift attributable to refractive index dispersion and particle shape so that the unit coating layers have interference reflection peaks or interference transmission bottoms at the same specific wavelength.