Pages: 12 Published: Jan 2012
SURFACE ACTIVE AGENTS OR “SURFACTANTS” represent a diverse spectrum of chemical compounds capable of modifying interfacial interactions by means of adsorption at interfaces. Since an interface is created when any two phases of immiscible components are present, it is virtually impossible to exclude or ignore interfacial aspects from any practical application. Coatings are no exception, but rather a unique expression of various surface phenomena governing the entire application. The advent of waterborne and water-based technologies produced more environmentally benign paint formulations, but brought along new technological challenges that did not exist in solvent-based paints. Considering that typical water-based paint consists of an emulsified binder and dispersed pigments, the complexity of paint formulations is caused not only by their multi-component composition but also their multiphase nature and inherent thermodynamic instability. In such complex systems, surfactants play an extremely important role, since they represent additives that facilitate dispersion, provide much desired shelf stability, and destabilize foam. Moreover, surfactants are used in coatings as wetting, coalescent and pigment dispersant agents to aid coating application, film formation and color development. In addition to the challenges provided by thermodynamic instability of paint systems and kinetics of their phase separation, environmental laws and regulations introduced new standards and additional requirements that will continue to have significant impact on the coating industry. Among many actions taken by state and federal legislative parties, the Clean Air Act of 1970 defines volatile organic contents (VOCs) and stipulates its permissible limits. In addition to the body of federal regulations, an increased consumers' awareness instigated new market initiatives that drive towards alkyl phenol ethoxylate (APEO), free consumer products. All these provide rather stringent guidelines to paint formulators with regard to the selection of dispersing media and functional additives, including surfactants.
Paper ID: MNL12211M
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