Polymers waterborne dispersion paints

Polymer Dispersions (Emulsion Polymers). Waterborne paints based on polymer dispersions (usually referred to as emulsion paints) are not water soluble. They are water-thinnable systems composed of dispersions of polymer particles in water (see Section 3.5). The particles consist of high molecular mass polymers (e.g., of styrene, butadiene, acrylate, or vinyl monomers) and are produced by emulsion polymerization. These waterborne paints also contain small amounts of organic solvents (< 5 wt %) that serve as film-forming (coalescing) agents that partially evaporate on drying. 

The required application viscosity of waterborne emulsion paints is generally obtained by adding a small volume of water. The evaporation behavior of polymer dispersions is similar to that of conventional, solvent-based paints. 

Waterborne dispersed polymers include both synthetic polymer dispersions and natural rubber. Synthetic polymer dispersions are produced by emulsion polymerization. A substantial part of the synthetic polymer dispersions is commercialized as dry products these include SBR for tires, nitrile rubbers, about 10% of the total PVC production, 75% of the total ABS and redispersable powders for construction materials. Carboxylated styrene-butadiene copolymers, acrylic and styrene-acrylic latexes and vinyl acetate homopolymer and copolymers are the main polymer classes commercialized as dispersions. The main markets for these dispersions are paints and coatings, paper coating, adhesives and carpet backing. 

According to Schulte and Hofer [18], typical waterborne latex paints for domestic exterior application usually contain about 30 wt.% water and about 15 wt.% of latex polymer together with about 0.3 wt.% dispersant (which presumably means... 

Despite a reputation for causing paint film defects, even polydimethylsiloxane-hydrophobed silica antifoams can also apparently find use in waterborne latex paints if certain preventive measures are applied (see, e.g., reference [28] and Section 9.3.2). It is tempting then to infer that, despite the complexity of waterborne latex paint formulations, the conventional oil-hydrophobed particle antifoams listed in Chapter 4 (Tables 4.A1 through 4.A3) find ready application in fhis context, albeit with additional components such as emulsifiers designed fo ease dispersal or structurants to ensure stability of the stored antifoam against sedimentation. Practical experience then implies that the rupture of foam films confaining high volume fractions of latex polymer particles by conventional antifoams is readily achieved. 

Emulsions are dispersions of one fluid into another. Both oil-in-water and water-in-oil emulsions are encountered. Foams are similar to emulsions, but the dispersed phase is a gas. Emulsions are everywhere some examples of products that are based on emulsions are salad dressings, mayonnaise, egg yolk, milk, margarine, cream, ice cream, waterborne paints and bitumen. Emulsions are generally not stable, so they need to be stabilized against coalescence. One can use surfactants for that, or polymers, such as proteins and polysaccharides, or particles. 

Waterborne paints differ according to the nature of their stabilization in water the polymer molecules are dissolved in water or dispersed in water in the form of polymer dispersions or emulsion polymers. Recent developments include polymer particles formed in organic solvents and then emulsified in water with low or, more commonly, high molecular mass emulsifiers being used for internal or external emulsification. Internal emulsification denotes that part of the binder molecule functions as an emulsifying moiety, whereas for external emulsification separate emulsifiers are required. 

Emulsion paints consist of polymer dispersions as binders, pigments, extenders, and small amounts of auxiliaries (in some cases < 1 %). Waterborne polymer dispersions are produced by emulsion polymerization monomer droplets are polymerized in water-containing surfactants and protective colloids. The size and size distribution of the dispersed polymer particles can be controlled by adjusting the stirring rate in the polymerization reactor and by selecting appropriate protective colloids. 

Alkyd paints dominated the architectural coating market for a long period until the appearance of polymer dispersions or the so-called latex paints. Specifically for wall application waterborne paints based on poly(vinyl acetate) homo- and copolymers, styrene-acrylics and pure acrylic latexes almost completely took over the market from the alkyd resins for both interior and exterior application. However, for... 

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