NUCLEATING AGENT FROM ARAMID OLIGOMER

PROBLEM TO BE SOLVED: To provide a nucleating agent useful as a modifying agent for a polymer base material, especially suitable for polyester, polyamide, etc. by composing the agent from a specific aramid oligomer comprising an aromatic diamine component and an aromatic carboxylic acid component. SOLUTION: This nucleating agent is obtained by composing the agent from an aramid oligomer which mainly comprises an aromatic diamine component and an aromatic carboxylic acid component and has a repeating unit of the formula [Ar1 and Ar2 are each a 6-12C divalent aromatic residue (of which the aromatic nucleus may be substituted); and (n) is a number of repeating units and is 1-10] as a main structural component. A by-product oligomer formed when a whole aromatic polyamide is produced by using m-phenylenediamine and isophthaloyl chloride is preferably used as the aramid oligomer. The thermoplastic polymer composition is obtained by adding the nucleating agent comprising the aramid oligomer to a thermoplastic polymer. The aramid oligomer is preferably added in an amount of 0.01-5 wt.% based on the composition. Polyester, polyamide or the like is preferably used as the thermoplastic polymer.