NITROGEN FLAME RETARDANT AND FLAME-RETARDANT POLYESTER RESIN COMPOSITION TO WHICH THE RETARDANT IS ADMIXED

PROBLEM TO BE SOLVED: To obtain the subject flame retardant that can provide a polyester resin composition having excellent flame retardancy, mechanical properties and processing characteristics in no need of a halogen-containing organic compound by admixing a condensation reaction product between a specific triazine compound and formaldehyde, or the like, at a specific ratio to the polyester resin. SOLUTION: One mole of (A) a triazine compound represented by the formula (R is H, an alkyl, an aryl, or the like; R1 and R2 are each a hydroxyalkyl, a carboxyalkyl, an alkoxyalkyl, or the like), for example, benzoguanamine, or the like, is allowed to react with 0.3-0.9 mole of (B) formaldehyde, for example, formalin in a solvent, for example, butanol in the presence of a catalyst, for example, hydrochloric acid, preferably at 80-100 deg.C for >=1 hour to prepare polycondensate products mainly comprising the polycondensate compounds. This flame retardant is used in an amount of 5-50 pts.wt. per 100 pts.wt. of the polyester resin.