Polyester resin composition

A polyester resin composition comprising:

• 1) 100 parts by weight of a resin composition consisting of 60 to 90 wt % of (a) a polyester resin with an amount of carboxyl end groups of from 35 to 49 eq/t and is at least one selected from the group consisting of polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate and their copolymers, and 10 to 40 wt % of (b) an olefin-based resin, and 2) 5 to 15 parts by weight of (c) one or more resins selected from polyphenylene sulfide resins and liquid crystal resins,
• wherein said olefin-based resin (b) comprises 3 to 20 wt % of (b-1) a functional group-containing olefin copolymer having at least one kind of functional groups selected from carboxylic acid groups, carboxylic anhydride groups and epoxy groups and 7 to 25 wt % of (b-2) an ethylene/α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin with 3 to 20 carbon atoms;
• and
• the polyester resin (a) forms a continuous phase, while the olefin-based resin (b) is dispersed as particles with an average particle size of 0.01 to 2 μm in the composition, and the polyphenylene sulfide resin (c) or liquid crystal resin is dispersed in the polyester resin (a) phase as particles having an average particle size of 1 to 100 nm and the polyphenylene sulfide has a melt viscosity of 12 to 40 Pa·s.