ABSTRACT

Table 12.1 Coating Properties That Are Either Controlled or Affected by Thickeners and Rheology Modifiers

In-can properties Application properties

Pigment suspension R Brushability and brush drag Syneresis R Film build and spread rate Color float R,C Flow and leveling Brush and roller pickup R Sag resistance Viscosity drop on tinting c Roller pattern Viscosity drop on water dilution c Spatter resistance

Sprayability and spray pattern

Paint film properties (interior) Paint film properties (exterior)

Hiding power C,R Dirt pickup Gloss development C,R Mildew resistance Scrubability C, A Adhesion and blister resistance Color compatibility and tint strength c Grain crack resistance Stain resistance and stain removal c Efflorescence

Corrosion resistance

R R,A R R R R R

influence on both coating performance and economics. In fact, many formulators now recognize that although thickeners and rheology modifiers are mi~or ingredients in a coating, they either control or significantly affect many important coating properties, some of which are shown in Table 12.1. Also included in this table are coating properties that may be affected by the chemical nature of the rheology modifier, the thickening mechanisms operative, and the thickening efficiencies of the modifiers used. To illustrate how small the thickener concentration is for such a broad impact on coating properties based on a 1996 survey of some 250 architectural interior and exterior coating formulas obtained from latex binder and thickener supplier literature [1], the total average thickener/rheology-modifier concentration

- was only 2.5% active on latex binder solids.