Abstract: A resin composition having high compositional uniformity can be advantageously prepared in industry by depositing a mixture comprising polyolefin particles and fibrous basic magnesium sulfate aggregated particles which satisfies the condition that a value resulting from calculation of formula of DA2×?A/DB2×?B is in the range of 0.2 to 5 in a hopper of a melt kneader through a supply port of the hopper and introducing the deposited mixture into the melt kneader so as to melt and knead the mixture therein, in which DA is a mean particle size (unit: cm) of the polyolefin particles, ?A is a density (unit: g/cm3) of the polyolefin, DB is a mean particle size (unit: cm) of the fibrous basic magnesium sulfate aggregated particles, and ?B is an apparent density (unit: g/cm3) of the aggregated particles.

Abstract: A resin composition having high compositional uniformity can be advantageously prepared in industry by depositing a mixture comprising polyolefin particles and fibrous basic magnesium sulfate aggregated particles which satisfies the condition that a value resulting from calculation of formula of DA2×?A/DB2×?B is in the range of 0.2 to 5 in a hopper of a melt kneader through a supply port of the hopper and introducing the deposited mixture into the melt kneader so as to melt and knead the mixture therein, in which DA is a mean particle size (unit: cm) of the polyolefin particles, ?A is a density (unit: g/cm3) of the polyolefin, DB is a mean particle size (unit: cm) of the fibrous basic magnesium sulfate aggregated particles, and ?B is an apparent density (unit: g/cm3) of the aggregated particles.

Abstract: A fine powder of an alkaline earth metal carbonate selected from the group consisting of barium carbonate, strontium carbonate and calcium carbonate, in which a primary particle of the powder has a mean diameter of 30 to 90 nm, in which the mean diameter is measured on a circle obtained from a projected area of the primary particle, and in which an accumulated volume of micropores having a pore size in the range of 10 to 20 nm is not less than 5×10?2 cm3/g can be easily dispersed in an aqueous medium in the form of essentially primary particles by an industrially employable dispersing method.

Abstract: A fine alkaline earth metal carbonate powder showing high dispersibility, in which the alkaline earth metal carbonate is selected from the group consisting of strontium carbonate and barium carbonate, can be prepared by a process comprising the steps of pulverizing a powder of strontium carbonate or barium carbonate in an aqueous medium using ceramic beads having a mean diameter of 10 to 1,000 ?m in the presence of a polymer comprising a polycarboxylic acid or anhydride thereof having a side chain of a polyoxyalkylene group, and drying the pulverized powder.

Abstract: A fine powder of an alkaline earth metal carbonate selected from the group consisting of barium carbonate, strontium carbonate and calcium carbonate, in which a primary particle of the powder has a mean diameter of 30 to 90 nm, in which the mean diameter is measured on a circle obtained from a projected area of the primary particle, and in which an accumulated volume of micropores having a pore size in the range of 10 to 20 nm is not less than 5×10?2 cm3/g can be easily dispersed in an aqueous medium in the form of essentially primary particles by an industrially employable dispersing method.