Unsaturated polyester resin composition, cured unsaturated polyester resin and lamp reflecting mirror base

An unsaturated polyester resin composition comprising unsaturated polyester resin in an amount of 8 to 20% by weight;

• liquid thermoplastic resin in an amount of 4 to 12% by weight;
• glass fiber in an amount of 8 to 20% by weight;
• and inorganic filler in an amount of 50 to 75% by weight,
• wherein said unsaturated polyester resin is comprised of unsaturated polyester in an amount of 65 to 75% by weight, which is obtained by polycondensation of a polyvalent alcohol component and one of α,β-unsaturated dibasic acid and anhydride thereof, said unsaturated polyester being dissolved by polymerizable unsaturated monomer in an amount of 25 to 35% by weight, and
• wherein said polyvalent alcohol component containing at least three members selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and neopentyl glycol so that said unsaturated polyester resin comprises 5.10 to 5.90 mmol/g of double bond group concentration, 1.50 to 2.50 mmol/g of ether linkage group concentration, 1.05 to 1.30 mmol/g of isopropylidene linkage group concentration, 2.50 to 3.50 mmol/g of ethylene linkage group concentration, and 3.20 to 3.60 mmol/g of methylene linkage group concentration per 1 g of unsaturated polyester.