Patent ID: 8445561

Claim:
A method of dry grinding calcium carbonate, the method comprising: (1) contacting a calcium carbonate with a grinding aid agent comprising a copolymer which comprises, in polymerized form: (a) an anionic monomer comprising acrylic acid, methacrylic acid, or a mixture thereof, (b) a non-ionic monomer of formula (I) wherein m, n, p, and q are integers such that m, n, and p≦150, q≧1, and 5≦(m+n+p)q≦150, R 1 and R 2 independently are hydrogen, a methyl radical, or an ethyl radical, R is a radical comprising an unsaturated polymerizable function which is vinylic, an acrylic ester, a methacrylic ester, a maleic ester, an acrylurethane, a methacrylurethane, an α-α′ dimethyl-isopropenyl-benzylurethane, an allylurethane, an optionally substituted allylic ether, an optionally substituted vinylic ether, an ethylenically unsaturated amide, an ethylenically unsaturated imide, an acrylamide, or a methacrylamide, and R′ is hydrogen or a hydrocarbon radical comprising 1 to 40 carbon atoms; and (c) optionally, a further monomer comprising (meth)acrylic anhydride, (meth)acrylamide, a (meth)acrylic ester with 1 to 20 carbon atoms in its ester radical, a hydroxylated methacrylate, an aromatic vinylic monomer, an organophosphate monomer, or a mixture thereof; and (2) dry grinding the calcium carbonate and the grinding aid.