METHOD FOR IMPROVING THE RHEOLOGICAL PROPERTIES OF WATER SUSPENSION OF PIGMENT, DISPERSANTER AND ITS APPLICATION

摘要

1. A method for improving the high-shear characteristics of an aqueous pigment suspension and its behavior in paper coating compositions, wherein the dispersant is added in the form of an aqueous polymer dispersion characterized by a solids content of 10-50% to the aqueous phase of the suspension containing pigment particles, or to the aqueous phase , in which the pigment particles must be added, while the dispersant contains a styrene-acrylate copolymer. 2. The method according to claim 1, characterized by adding at least 0.1 parts of a dispersant containing a styrene-acrylate copolymer, based on 100 parts of the pigment in suspension. The method according to claim 1, characterized in that a conventional dispersant such as a straight chain polyacrylate is also added to the aqueous phase. A method according to any one of the preceding claims 1 to 3, characterized by the addition of a dispersant during the last stages of wet grinding of the pigment in case the pigment particles have already obtained the desired particle size. A dispersant for a pigment suspension containing a first component containing a styrene-acrylate copolymer in the form of an aqueous polymer dispersion characterized by a solids content of 10-50%, and a second component containing a conventional dispersant, such as a straight chain polyacrylate. 6. The dispersant according to claim 5, characterized in that the first component contains a styrene-acrylate copolymer, which is obtained by copolymerization of styrene or substituted styrene, such as α-methyl styrene or vinyl toluene, or a mixture thereof, and C1-C4 alkyl acrylates, C1-C4 alkyl methacrylates or mixtures thereof. 7. Dispersant according to claim 5 or 6, characterized in that the second component is a straight-chain polyacrylate, floor