Behavior of Pigments in Binders

For standards, see Table 1 ( Corrosion testing NaCl ). Materials and apparatus spray chamber, test solutions (5 % NaCl solutions). 

Resistance to Spittle and Sweat. This test indicates whether a pigment on a child s colored toy is likely to be transferred to the mouth, mucous membranes, or skin during use. Strips of filter paper are wetted with NaHC03 and NaCl solutions and pressed against the test samples. The discoloration of the paper is judged visually. 

The discoloration of the paper is judged visually. For standards, see Table 1.1 ( Spit-tle/sweat resistance ). 

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All components fulfill special functions in the liquid paint and in the solid coating film. Solvents, binders, and pigments account for most of the material, the proportion of additives being small. Low concentrations of additives produce marked effects such as improved flow behavior, better wetting of the substrate of pigment, and catalytic acceleration of hardening. 

Special effect pigments are used as colorants or part of color formulations for all systems where traditional pigments are applied, but where additional color depth, brilliance, iridescence, color travel, and other spectacular effects are required [5.122, 5.123]. Mica-based pigments dominate their combination of pearl and interference effects, brilliance, stability and behavior in different application systems is as yet unsurpassed. Pearl luster pigments require transparent or at least translucent binders. Formulations with absorption pigments have to take their transparency and color mixing rules into account... 

One of the most typical properties of metallic pigments is their wetting behavior in different solvents (including water) or binder solutions. Metal effect pigments are basically divided into leafing and non-leafing types (Figure 5.29). 

Styrene-Modified Alkyd Resins. Styrene was first copolymerized with drying oils in the early 1940s. These binders had a substantially improved drying behavior and resistance to water and chemicals compared with untreated oils. The first patents for the production of styrenated alkyd resins were granted in the United Kingdom in 1942 [2.63]. Mixtures of styrene and a-methylstyrene are also used for a more reliable reaction vinyltoluene yields copolymers with improved thinnability in mineral spirit and pigment absorption. 

The binder is the most important component of a paint formulation. It binds the pigment particles in a homogeneous dispersion and fixes these particles to the painted surface, providing a final continuous film. Binders determine the application method, drying and hardening behavior, adhesion to the substrate, mechanical properties, and chemical and weathering resistance of the paints. The binder is dissolved in an appropriate solvent, and both binder and solvent constitute the vehicle of the paint. 

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