Abstract: A colorless thermoplastic polyester resin composition that can form a molded article with good appearance is provided. More specifically, a thermoplastic polyester resin composition is provided, which has (A) polybutylene terephthalate resin, (B) polyethylene terephthlatae resin, (C) nigrosine dye, and (D) glass fibers. The blending amounts are (A) in the range of 55-86 wt. % and (B) in the range of 14-45 wt. % based on 100 wt. % of a total of (A) and (B). Further, (C) is in the range of 0.1-1.5 parts by weight based on 100 parts of a total of (A) and (B). Preferably, the carboxy terminal groups of (A) is at 25 (eq/t), the intrinsic viscosity of (A) is in the range of 0.60-0.90, and the melting point of (C) is less than 300° C.

Abstract: A colorless thermoplastic polyester resin composition that can form a molded article with good appearance is provided. More specifically, a thermoplastic polyester resin composition is provided, which has (A) polybutylene terephthalate resin, (B) polyethylene terephthlatae resin, (C) nigrosine dye, and (D) glass fibers. The blending amounts are (A) in the range of 55-86 wt. % and (B) in the range of 14-45 wt. % based on 100 wt. % of a total of (A) and (B). Further, (C) is in the range of 0.1-1.5 parts by weight based on 100 parts of a total of (A) and (B). Preferably, the carboxy terminal groups of (A) is at 25 (eq/t), the intrinsic viscosity of (A) is in the range of 0.60-0.90, and the melting point of (C) is less than 300° C.

Abstract: A thermoplastic polyester resin composition having: 100 parts by weight total of a resin composition, wherein the resin composition has 75 to 99 wt % of (A) a polybutylene terephthalate resin, and 1.0 to 25 wt % of (B) a polyester elastomer resin and/or an olefin elastomer; and 0.01 to 5 parts by weight of (C) a sorbitan fatty acid ester. The thermoplastic polyester resin composition is useful for making electric/electronic device parts, automobile parts and machine parts, as well as connectors.