Abstract: The present invention is to provide a physically well-balanced resin composition excellent in strength, rigidity and heat resistance as well as in percent weld strength retention, dimensional properties, external surface appearance and reworkability.

Abstract: Block copolymer comprising at least two kinds of polymer components each having a different structural unit in the polymer selected from polyamide, polyester, polycarbonate and polyarylate. The present block copolymer has a distinguished moldability and can be produced even from rework products or recycle products in a simple and economical manner.

Abstract: A polyamide resin composition which contains 0.5 to 50 wt. % of an apatite type compound and which, when eluted with a phenol solvent and filtered, leaves 1 to 100 parts by weight of residual organic substances per 100 parts by weight of the apatite type compound has high strength and rigidity and is excellent in toughness. Moreover, the composition is reduced in water absorption and warpage and is excellent in rigidity upon water absorption, heat resistance, creep resistance, dimensional stability and moldability. Thus, the composition is suitable for use as an industrial material for producing mechanical parts, electrical/electronic parts, etc.