Abstract: Improved aqueous slurry type coating colors for coating of paper, paperboard and the like are described in which there is incorporated along with the usual finely divided inorganic pigments, such as clay, an auxiliary pigment consisting of a substantially water-insoluble, cross-linked urea-formaldehyde resin in highly dispersed particulate form. The urea-formaldehyde pigment constitutes from about 2 to 25% and preferably from about 3 to about 15% by weight of the total pigment solids in the coating colors. The BET specific surface area of the particulate urea-formaldehyde pigments ranges from about 40 to about 75 square meters per gram in which instance the average agglomerate size of the pigments ranges from about 2 to about 3.5 microns. In those instances where the BET specific surface area of the urea-formaldehyde pigments ranges from at least 15 to 40 square meters per gram, the average agglomerate size of the pigments ranges from about 2 to about 4 microns.

Abstract: Improved aqueous slurry type coating colors for coating of paper, paperboard and the like are described in which there is incorporated along with the usual finely divided inorganic pigments, such as clay, an auxiliary pigment consisting of a substantially water-insoluble, cross-linked urea-formaldehyde pigment in highly dispersed particulate form. The urea-formaldehyde pigment constitutes from about 2 to 25% and preferably from about 3 to about 15% by weight of the total pigment solids in the coating colors. The BET specific surface area of the particulate urea-formaldehyde pigments ranges from about 40 to about 75 square meters per gram in which instance the average agglomerate size of the pigments ranges from about 2 to about 3.5 microns. In those instances where the BET specific surface area of the urea-formaldehyde pigments ranges from at least 15 to 40 square meters per gram, the average agglomerate size of the pigments ranges from about 2 to about 4 microns.