THERMOPLASTIC RESIN COMPOSITION

PROBLEM TO BE SOLVED: To obtain a thermoplastic resin composition which can give a product improved in bending modulus, bending strength and Izod impact strength by mixing a thermoplastic resin with an inorganic filler and a specified block copolymer. SOLUTION: A polymer obtained by radical-polymerizing a monomer component constituting a polymer block compatible with a thermoplastic resin in the presence of a compound having a thioester group and a mercapto group in the molecule is treated with an acid or an alkali to obtain a polymer having a mercapto group at either terminal. 0.1-100mol% vinyl monomer having at least one functional group selected among a carboxyl group, an epoxy group and an acid anhydride group and 99.9-0mol% vinyl monomer copolymerizable therewith are radical-polymerized in the presence of the above obtained polymer to obtain a block copolymer. 100 pts.wt. mixture comprising 40-98 pts.wt, thermoplastic resin and 60-2 pts.wt. inorganic filler having a mean particle diameter of 0.1-200μm is mixed with 0.05-20 pts.wt. above block copolymer.