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AssigneeBASF SE
InventorsWalter Denzinger, Heinrich Hartmann, Guenter Hirsch, Hans-Werner Becker, Michael Rohmann
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Polymers of acrylic acid or methacrylic acid are prepared by polymerizing acrylic acid and/or methacrylic acid at 50.degree.-180.degree. C. in a C.sub.2 -C.sub.6 -alcohol or mixtures thereof with water having a C.sub.2 -C.dwnarw.6.uparw.-alcohol content of not less than 40% by weight in the presence of free radical polymerization initiators and from 0.01 to 5% by weight, based on the monomers used, of inorganic acids of phosphorus in which the phosphorus has an oxidation number of from 1 to 4, or of water-soluble salts thereof, water-soluble --PO(OH).sub.2 -containing compounds and/or water-soluble salts thereof. The polymers thus prepared are effective milling aids and dispersants for pigments for producing aqueous pigment slurries for use in paper-coating compositions.
A process for preparing a polymer of acrylic acid or methacrylic acid by polymerizing acrylic acid, methacrylic acid, or mixtures thereof, if desired together with up to 10% by weight of another ethylenically unsaturated compound copolymerizable therewith, at 40.degree.-180.degree. C. in a secondary C.sub.2 -C.sub.6 -alcohol or a mixture thereof with water with a C.sub.2 -C.sub.6 -alcohol content of not less than 40% by weight in the presence of a free radical polymerization initiator and of from 0.01 to 5% by weight, based on the monomers used, of an inorganic acid of phosphorhus in which the phosphorus has an oxidation number of from 1-4, a water-soluble salt thereof, a water-soluble --PO(OH).sub.2 -containing compound, a water-soluble salt thereof, or mixtures thereof.
Dependencies are inferred from the claim text.