Архивы рубрики ‘Understanding. Coatings Raw Materials’

Authors

Dr. Vijay Mannari is professor at Eastern Michigan University where he teaches polymers and coatings technology. He is a gifted instructor and accomplished researcher with more than 25 years of combined industrial, academic and consulting experience in the field of resins, paints and coatings. He has published more than 40 research papers, has given numerous […]

Additives to modify conductivity

Electrostatic spraying, one of the important coating application tech­niques, relies on an electric charge on atomized droplets of the paint for higher transfer efficiency. The charged droplets are attracted to the surface of the target object, which has been grounded. Too high an electrical resistance of the liquid paint material would result in poor application […]

Moisture scavengers

Certain coating systems such as polyurethane or coatings contai­ning metallic pigments such as aluminum or zinc are very sensitive to moisture. Moisture can get into the coatings by a variety of routes, such as by being dissolved in solvents or absorbed onto the surface of pigments and extenders. To avoid the potential problems due to […]

Freeze-thaw stabilizers

Waterbased coatings have the inherent problem of the high free­zing point of water. When some waterbased systems are exposed to subzero temperatures, water will freeze, causing destabilization of the paint. To resolve the problem, anti-freezing agents are added to depress the freezing point of the water in paints, and are com­monly known as freeze-thaw stabilizers. […]

Inhibitors for long-term protection

Inhibitors for long-term protec­tion are substances with low water solubility. The commer­cially available products are either used as a replacement for traditional anticorrosive pig­ments as the sole inhibitor or in combination with pigments to synergistically enhance anodic pro­tection. Their use in coatings is expected to increase with rapid development of waterbased anticorrosive paints, in which […]

Flash-rust inhibitors

Flash rusting is the phenomenon of formation of small brown rust spots that appear very soon after application of waterbased systems directly to steel. The problem is more prominent when the steel sur­face is active (for example, after blasting) and the pH is <7. To combat this problem, flash-rust inhibitors are added to waterbased coatings. […]

Corrosion inhibitors

Protecting metallic substrates against corrosion is one of the prime functions of most coatings. Corrosion resistant coatings are typi­cally formulated using anticorrosive pigments and suitable bin­ders with the optimum formulation parameters. In addition, organic compounds known as corrosion inhibitors are often added at low levels, and can effectively reduce the corrosion rate of a metal […]

Dry-film preservatives

Dry films are also subject to microbiological attack by fungi and algae, which impairs the aesthetic appearance of the film by discolo­ration or patching. In certain situations, this also affects film integrity and hence performance of the coatings. Dry-film preservatives are aimed at preventing the growth of bacteria, fungi, and algae on the paint film […]

In-can preservatives

In general, in-can preservation is a much bigger problem for water­borne paint compared to solventbased paints. In solventbased coatings, the organic solvents are not conducive to growth of micro­organisms. Microbial growth in liquid paint may often result in problems such as gassing, obnoxious odor, staining, pH drift and viscosity drop in paints containing cellulosic thickeners. […]

Biocides

Biocides are compounds that, even at low concentration, inhibit the growth of microorganisms. Many coatings are susceptible to attack, both in-can and as dry films, by microorganisms such as bacteria, fungi and algae. Addition of biocides such as fungicides, bactericides and algaecides are necessary to eliminate problems caused by microbiological attack. Based on their purpose […]