Process for grinding calcium carbonate in aqueous media
AssigneeCoatex
InventorsHubert Bousquet, Georges Ravet, Jacky Rousset
Life of this patent
Estimating the term…
Abstract
Ground calcium carbonate is prepared by a process of grinding a suspension containing calcium carbonate and a water-soluble grinding agent in an aqueous medium while the temperature of the aqueous suspension is kept at or below 60.degree. C.
Claims20
In a process for grinding coarse calcium carbonate in the presence of a water-soluble polymeric grinding agent composed of at least one acidic polymer and/or copolymer obtained from at least one carboxylated ethylenic monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic anhydride, isocrotonic acid, aconitic acid, mesaconic acid, sinapic acid, undecylenic acid, angelic acid, and .alpha.-hydroxyacrylic acid to produce an aqueous suspension of at least 70% by weight of calcium carbonate having a particle size no larger than about 2 .mu.m and at least 60% of the particles having a particle size below 1 .mu.m, the improvement which comprises:
- maintaining the temperature of the aqueous suspension below 45.degree. C. during the grinding step, wherein the grinding agent is introduced into the aqueous medium at an amount of 0.05% to 1.0% by weight relative to the dry weight of calcium carbonate.
In a process for grinding coarse calcium carbonate in the present of a water-soluble polymeric grinding agent composed of at least one acidic polymer and/or copolymer obtained from at least one carboxylated ethylenic monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic anhydride, isocrotonic acid, aconitic acid, mesaconic acid, sinapic acid, undecylenic acid, angelic acid, and .alpha.-hydroxyacrylic acid to produce an aqueous suspension of at least 70% by weight of calcium carbonate having a particle size no larger than about 2 .mu.m and at least 60% of the particles having a particle size below 1 .mu.m, the improvement which comprises:
- maintaining the temperature of the aqueous suspension below 45.degree. C. during grinding step, wherein the grinding agent is introduced into the aqueous medium at an amount of 0.1% to 0.8% by weight relative to the dry weight of calcium carbonate.
Dependencies are inferred from the claim text.