Coatings
Source Reduction, Alternative Processes
High Solids. Although air pollution agencies actively promote water-borne coatings, all solvent-borne coatings cannot yet be replaced. Some companies will require solvent-borne coatings into the 21st century. Fortunately, VOC con-tents are gradually decreasing, viscosities are becoming more manageable, and paint chemists continue work on developing new solvents that are not VOCs, hazardous air pollutants (HAPs), or ozone depleting compounds (ODCs). These new solvents may offer a wide range of new opportunities.
Water-Borne. The term "water-borne" describes coatings in which the dominant solvent is water. Organic solvents (VOCs) are also used but, for the most part, their concentration is small. In many formulations the ratio between the amount of water and organic solvent is 80:20.
UV Cure. These unique coatings cure when they are exposed to specific wavelengths of ultraviolet (UV) or electron beam (EB) radiation. Like the other specialized coatings, radiation cured coatings constitute the ideal choice for a very narrow niche of the overall coatings market. They are included here because their VOC emissions are very Iow, even approaching zero for some formulations. The coatings have Iow VOC emissions because curing takes place without the need for solvents to evaporate.
Powder Coating. As the name implies, Powder coatings are organic coatings that are supplied in dry powder form. Unlike liquid coatings, each discrete powder particle contains the entire coating formulation, namely the resins, pigments, fillers, and modifiers. A powder coating contains no solvents. The powder particles are extremely finely divided and resemble talcum powder.
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