Influences of Different Rheological Agent on the Rhology Behavior of Coatings

The main purpose of adding rheological agent into the coating formulation is to change the viscosity of the system.The system is very viscous and has good water retention when it is under low shear rate,on the contrary the viscosity of the system is decreased,while flowing property is better when the system is under high shear rate.CMC and L255 respectively belongs to cellulosic thickener and synthetic thickener with different properties and thickening mechanism.They have dissimilar influences on the water retention ability and rheology modification of coating system.The influence of CMC on the viscosity of primer coatings of whiteboard was studied.Moreover,take the top coatings for example,compared with CMC,the addition of L255 contributes to the increasement of low-mid shear apparent viscosity(10～1000 s-1)remarkably,while the downtrend of viscosity(1000 s-1)is more pronounced as the shear rate is increasing.