Patent ID: 8247483

Claim:
A process for producing a rotation molded body by rotation molding of a polyolefin composition comprising a polyolefin and a phosphite of the formula (I): (in the formula (I), R 1 , R 2 , R 4 and R 5 represent each independently a hydrogen atom, alkyl group having 1 to 8 carbon atoms, cycloalkyl group having 5 to 8 carbon atoms, alkylcycloalkyl group having 6 to 12 carbon atoms, aralkyl group having 7 to 12 carbon atoms or phenyl group, R 3 represents a hydrogen atom or alkyl group having 1 to 8 carbon atoms, X represents a single bond, sulfur atom or —CHR 6 — group (R 6 represents a hydrogen atom, alkyl group having 1 to 8 carbon atoms or cycloalkyl group having 5 to 8 carbon atoms), A represents an alkylene group having 1 to 8 carbon atoms or *—COR 7 — group (R 7 represents a single bond or alkylene group having 1 to 8 carbon atoms, and * means that the group is a connecting bond at the oxygen side), and either one of Y and Z represents a hydroxyl group, alkoxy group having 1 to 8 carbon atoms or aralkyloxy group having 7 to 12 carbon atoms and other one represents a hydrogen atom or alkyl group having 1 to 8 carbon atoms), wherein the polyolefin composition further comprises tris(2,4-di-t-butylphenyl)phosphite, the weight ratio of the phosphite of the formula (I) to tris(2,4-di-t-butylphenyl)phosphite being 5:1 to 1:10.