THERMALLY STABILIZED POLYOLEFIN RESIN COMPOSITION

PURPOSE:To obtain a polyolefin resin composition having extremely excellent heat stability, comprising a hindered phenol-based heat stabilizer, hindered amine-based weather resistance imparter and a small amount of organic hypophosphorous acid compound. CONSTITUTION:100 pts.wt. polyolefin resin is blended with (A) 0.01-10 pts.wt., preferably 0.05-1 pt.wt. hindered phenol-based heat stabilizer, (B) 0.01-10 pts.wt., preferably 0.05-1 pt.wt. hindered amine-based weather resistance imparter and (C) an organic hypophosphorous acid compound shown by formula I [X is >=1C organic cation; a and b are natural number and aXc=b (c is valence of X), preferably a compound shown by formula II (R1 is 1-22C alkyl or benzyl]; R2 to R4 are H, 1-22C alkylor benzyl), formula III (R1 to R6 are H, 1-22C alkyl or benzyl) or formula IV (R1 to R4 are 1-22C alkyl, phenylor benzyl) in a ratio of 0.05>C/B>=0.001.