Abstract: Provided is a calcium carbonate filler which gives films and the like excellent in moldability, dispersibility, gasmark (bubbles), hue, and further, excellent in optical properties such as reflectivity and light resistance when incorporated into a resin to prepare a resin composition.

Abstract: Provided is a calcium carbonate filler which gives films and the like excellent in moldability, dispersibility, gasmark (bubbles), hue, and further, excellent in optical properties such as reflectivity and light resistance when incorporated into a resin to prepare a resin composition. A calcium carbonate filler for a resin, satisfying the following expressions (a), (b), and (c): 1.0?Sw?10.0 (m2/g),??(a) 0.01?Tw?0.5(% by weight), and??(b) 80?Lw?90??(c) wherein Sw represents a BET specific surface area (m2/g) measured by using a BET specific surface area measuring device (Macsorb manufactured by Mountech Co., Ltd.); Tw represents a weight reduction value (% by weight) measured at 200° C. to 300° C. by using a differential thermogravimetric device (Thermo Plus EVO II manufactured by Rigaku Corporation); and Lw represents a degree of whiteness (L value) measured by using a spectroscopic color-difference meter (ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.).

Abstract: Provided is a surface treated calcium carbonate filler for resins, which comprises calcium carbonate particles, the surface of which has been treated with at least one surface active agent (A) selected from the group consisting of saturated fatty acids, unsaturated fatty acids, alicyclic carboxylic acids, resin acids, and salts thereof and with at least one compound (B) having the ability to chelate alkaline earth metals, the compound (B) being selected from the group consisting of phosphonic acids, polycarboxylic acids, and salts thereof. The surface treated calcium carbonate filler for resins of the present invention deteriorates little with time, has satisfactory dispersibility in resins, and can give a sheet or film which has a satisfactory balance among durability, weatherability, strength, and thermal stability, and is useful as a battery separator or a light reflector.

Abstract: A calcium carbonate filler for a resin, in which the content rate of particles having a particle diameter of 0.26 ?m or less is 30% or less in a number particle size distribution diameter measured (Mac-VIEW manufactured by Mountech) from an electron micrograph, and which satisfies the following expressions (a) to (c) is provided. Dms5/Dmv5?3??(a) 1?Sw?8 (m2/g)??(b) Mo?300 (ppm)??(c) wherein Dms5: A 5% diameter (?m) accumulated from a small particle side in a volume particle size distribution by a laser diffraction particle size distribution measuring device (MASTERSIZER2000 manufactured by Malvern); Dmv5: A 5% diameter (?m) accumulated from a small particle side in a number particle size distribution in a particle diameter (Mac-VIEW manufactured by Mountech) measured with an electron microscope; Sw: A BET specific surface area (Macsorb manufactured by Mountech) (m2/g); Mo: A water amount (ppm) by the Karl Fischer method at 200 to 300° C.

Abstract: A calcium carbonate filler for a resin, in which the content rate of particles having a particle diameter of 0.26 ?m or less is 30% or less in a number particle size distribution diameter measured (Mac-VIEW manufactured by Mountech) from an electron micrograph, and which satisfies the following expressions (a) to (c) is provided. Dms5/Dmv5?3??(a) 1?Sw?8 (m2/g)??(b) Mo?300 (ppm)??(c) wherein Dms5: A 5% diameter (?m) accumulated from a small particle side in a volume particle size distribution by a laser diffraction particle size distribution measuring device (MASTERSIZER2000 manufactured by Malvern); Dmv5: A 5% diameter (?m) accumulated from a small particle side in a number particle size distribution in a particle diameter (Mac-VIEW manufactured by Mountech) measured with an electron microscope; Sw: A BET specific surface area (Macsorb manufactured by Mountech) (m2/g); Mo: A water amount (ppm) by the Karl Fischer method at 200 to 300° C.

Abstract: Provided is a surface treated calcium carbonate filler for resins, which comprises calcium carbonate particles, the surface of which has been treated with at least one surface active agent (A) selected from the group consisting of saturated fatty acids, unsaturated fatty acids, alicyclic carboxylic acids, resin acids, and salts thereof and with at least one compound (B) having the ability to chelate alkaline earth metals, the compound (B) being selected from the group consisting of phosphonic acids, polycarboxylic acids, and salts thereof. The surface treated calcium carbonate filler for resins of the present invention deteriorates little with time, has satisfactory dispersibility in resins, and can give a sheet or film which has a satisfactory balance among durability, weatherability, strength, and thermal stability, and is useful as a battery separator or a light reflector.