Granular composite additive for polyolefin, process for producing the same, and polyolefin composition containing the same

A multi-component granule additive for polyolefin, the additive comprising a nucleating agent that comprises an alkali metal salt or hydroxyaluminum salt of an aromatic monocarboxylic acid or comprises an alkali metal salt or hydroxyaluminum salt of an acid aromatic phosphoric ester compound, in an amount of 10 parts by mass;

• a phenolic antioxidant in an amount of 1-50 parts by mass;
• polypropylene in an amount of 5-50 parts by mass;
• and at least one additive component, serving as an optional component, other than the nucleating agent, the phenolic antioxidant, and the polypropylene component in an amount of 0-500 parts by mass, wherein the granule additive has a ratio by mass (percent pulverization) of the particles which pass through a 16-mesh sieve of 1.0% or less as measured in a pulverization acceleration test by use of a shaking apparatus.