Crystal nucleating agent for polyolefin resin, method for producing crystal nucleating agent for polyolefin resin, and method for improving fluidity of crystal nucleating agent for polyolefin resin

A method for improving the fluidity of a crystal nucleating agent for polyolefin resins, comprising adjusting the nucleating agent to have an aerated bulk density within a range of 0.25 to 0.50 g/cm3, a packed bulk density within a range of 0.3 to 0.80 g/cm3, and a powdering rate of 40% or lower,

• wherein the crystal nucleating agent for polyolefin resins is a granule obtained by preparing a mixture containing a starting powder of the crystal nucleating agent for polyolefin resins and a compound having a binder effect, extrusion-granulating the mixture, and removing the compound having a binder effect from the extrusion-granulation product, and
• wherein the crystal nucleating agent for polyolefin resins consists of a diacetal compound represented by the following formula (1):
• wherein R1 and R2 are the same as or different from each other and each represent a hydrogen atom, a C1-C4 linear or branched alkyl group, a C1-C4 linear or branched alkoxy group, a C1-C4 linear or branched alkoxy carbonyl group, or a halogen atom;
• R3 represents a hydrogen atom, a C1-C4 linear or branched alkyl group, a C2-C4 linear or branched alkenyl group, or a C1-C4 linear or branched hydroxy alkyl group;
• m and n each represent an integer of 1 to 5;
• p represents 0 or 1;
• and two R1s optionally bind to each other to form a tetralin ring together with a benzene ring to which they are bonded and two R2s optionally bind to each other to form a tetralin ring together with a benzene ring to which they are bonded.