Method for coloring building materials using a cationic pigment dispersion

Abstract

A cationic dispersion which includes at least one pigment, water, and at least one quaternary salt of a styrene maleimide imide resin in an amount effective to disperse the organic pigment. A method for preparing the cationic dispersion includes (i) mixing, at 500 to 10,000 rpm, at least one pigment; water; and either (a) at least one a quaternary salt of a styrene maleimide imide resin or (b) at least one styrene maleimide imide resin in combination with at least one weak acid, thereby forming a dispersion premix; (ii) milling the dispersion premix in a mixer filled with ceramic, metal or glass beads for a period of time sufficient to reduce pigment agglomerates to primary particles, thereby forming a non-standardized dispersion; and (iii) standardizing the dispersion against a color standard by adding water. The resulting cationic dispersion exhibits good alkali resistance and lightfastness, and can be used to integrally color concrete and other building materials.

1 . A cationic dispersion, comprising: 
 (i) at least one pigment;    (ii) at least one dispersing agent comprising a quaternary salt of a styrene maleimide imide resin; and    (iii) water.    
     
     
         2 . The cationic dispersion of  claim 1 , wherein said pigment is an organic pigment is selected from the group consisting of phthalocyanine green, phthalocyanine blue, carbazole violet, toluidine red, Dalamar yellow, Watchung red and diketopyrrolopyrrole.  
     
     
         3 . The cationic dispersion of  claim 2 , wherein said organic pigment is a phthalocyanine.  
     
     
         4 . The cationic dispersion of  claim 1 , wherein said pigment is an inorganic pigment selected from the group consisting of red oxide, yellow oxide, black iron oxide, cobalt blue, carbon black and bismuth vanadate.  
     
     
         5 . The cationic dispersion of  claim 1 , further comprising at least one member of the group consisting of a defoamer, a biocide and a viscosity control agent.  
     
     
         6 . The cationic dispersion of  claim 1 , wherein said pigment comprises primary particles.  
     
     
         7 . A process for preparing a cationic dispersion, comprising: 
 (i) mixing, at 500 to 10,000 rpm, at least one pigment, water, and either (a) at least one a quaternary salt of a styrene maleimide imide resin or (b) at least one styrene maleimide imide resin in combination with at least one weak acid, thereby forming a dispersion premix;    (ii) milling the dispersion premix in a mixer filled with ceramic, metal or glass beads for a period of time sufficient to reduce pigment agglomerates to primary particles, thereby forming a non-standardized dispersion;    (iii) adding water to the non-standardized dispersion until it matches a color standard and forms a cationic dispersion suitable for coloring building materials.    
     
     
         8 . The method of  claim 7 , wherein said pigment and water are mixed with at least one quaternary salt of a styrene maleimide imide resin.  
     
     
         9 . The method of  claim 7 , wherein said pigment and said water are mixed with at least one styrene maleimide imide resin in combination with at least one weak acid.  
     
     
         10 . The method of  claim 9 , wherein said weak acid is at least one member selected from the group consisting of acetic acid, citric acid, carbonic acid, hydrofluoric acid, oxalic acid and nitrous acid.  
     
     
         11 . A colored building material, comprising the cationic dispersion of  claim 1  dispersed in a building material.  
     
     
         12 . The colored building material of  claim 11 , wherein said building material is selected from at least one member of the group consisting concrete, asphalt, plaster, mortar and cement mortar.