Abstract: A pigment master batch suitable for filler-containing polypropylene compositions is provided. This pigment master batch comprises 100 parts by weight of a propylene homopolymer having a melt flow rate of at least 10 g/10 min. and 30-200 parts by weight of a processed pigment prepared by using a metallic salt of a fatty acid, a polyethylene wax or a polypropylene wax as a dispersion medium for pigment. A filler-containing polypropylone composition in which the above pigment master batch is incorporated is superior in dispersibility and balance of properties and can easily be processed into molded articles which are superior in balance of properties such as heat resistance, impact resistance and rigidity.

Abstract: The present invention provides a novel method for producing a filler-containing colored thermoplastic resin composition superior in pigment dispersibility and impact resistance. This method includes melt kneading firstly at least a part of components of resin consisting of a thermoplastic resin (A) and/or a thermoplastic resin composition (B) with fillers (C), adding remainder of the resin, if any, with a pigment (E), and then further carrying out continuous melt-kneading.