Gycol dispersion of calcium carbonate

Claim 2

A glycol dispersion consisting of calcium carbonate and glycol prepared by wet grinding a glycol slurry composed of glycol and a material in powder form to be wet-ground, wherein said material to be wet-ground is calcium carbonate surface-treated with at least one surface treating agent selected from the group consisting of a copolymer (A) of at least one of an α,β-monoethylenically unsaturated carboxylic acid and its salt with an α, β-monoethylenically unsaturated carboxylic acid ester, and a salt (B) of a copolymer of an α, β-monoethylenically unsaturated carboxylic acid with an α, β-monoethylenically unsaturated carboxylic acid ester, the proportion of the α, β-monoethylenically unsaturated carboxylic acid ester to the copolymer is not less than 2 mol % and not more than 95 mol %.

Claim 3

A glycol dispersion of claim 1, wherein the calcium carbonate to be surface-treated is precipitated calcium carbonate meeting the requirements described below in (a) and (b), said surface-treated precipitated calcium carbonate is used as wet grinding material and a glycol slurry consisting of said wet grinding material and glycol is wet-ground under the conditions described below in (2); wherein (a) the primary particle size D 1 calculated by the following formula (1) from the specific surface area S 1 measured by the BET method is not less than 0.1 μm: Dx=60,000/2.7Sx (1) wherein, Dx is the average particle size (μm) of precipitated calcium carbonate calculated from the specific surface area measured by the BET method; and Sx is the specific surface area (cm 2 /g) of precipitated calcium carbonate measured by the BET method; (b) the ratio (R 1 ) of the 50% weight average particle size d 1 of particle size distribution measured in an aqueous medium by the use of Light Transmission Centrifugal Precipitation-Type Particle Size Distribution Measuring Device (manufactured by Shimazu Seisakusho Ltd.) to the aforesaid D 1 satisfies the following formula (2): R.sub.1 =d.sub.1 /D.sub.1 ≦7 (2); (c) the ratio (R 2 ) of the aforesaid primary particle size D 1 to the primary particle size D 2 calculated by the aforesaid formula (1) from the specific surface area S 2 of wetground precipitated calcium carbonate measured by the BET method satisfies the following formula (3): R.sub.2 =D.sub.1 /D.sub.2,1<R.sub.2 ≦10 (3).

Claim 4

A glycol dispersion of claim 1, wherein the amount of the surface treating agent is not less than 0.01 weight % and not more than 30 weight % (as 100% pure) based on calcium carbonate.