Patent ID: 7863367

Claim:
A surface treated calcium carbonate for use in a curable resin in which calcium carbonate is surface treated with a surface treatment composition comprising at least one selected from the group consisting of a fatty acid having an alkyl group of 12 carbon atoms and a fatty acid having an alkyl group of 14 carbon atoms; wherein the sum of the weight of fatty acids having an alkyl group of 12 carbon atoms and the weight of fatty acids having an alkyl group of 14 carbon atoms is 85% or more of the total weight of fatty acids in the surface treatment composition; and wherein the surface treated calcium carbonate satisfies Pvâ‰¦90(%) and is dried using a drier having a sufficient residence time to supply heat quantity such that the fatty acid surface treatment composition penetrates into secondary agglomerated particles of calcium carbonate; wherein Pv is a parameter representing a state of being treated with a surface treatment composition, Pv being a ratio of a volume (vol. %) precipitated in hexane to a total volume 100 ml of hexane and surface treated calcium carbonate, Pv being determined by: charging hexane and the surface treated calcium carbonate in a ratio of 100 g/10 g into a container, shaking the content of the bottle at a shaking frequency of 300 times per minute for 10 minutes using a shaker, transferring the resulting shaken mixture into a 100 ml measuring cylinder up to 100 ml, and allowing the resulting shaken mixture to stand at 23Â° C. for 24 hours during which the mixture separates into a hexane layer and a precipitated layer, measuring a volume of the precipitated layer, and, determining a ratio of the measured volume of the precipitated layer to a total volume 100 ml of hexane and surface treated calcium carbonate.