Developments in Additives

There continues to be a significant need to advance the technology of coatings to address competitive commercial production challenges, application demands and priority performance needs. The critical role of additives in coatings to influence their formulation, application and performance continues to be a strong focus of research and development efforts. Recent advances in nano-materials and their application in coatings are beginning to provide many new opportunities to seek enhancements in the preparation and performance of coating systems.

In coating performance, additive contributions to applied paint self-healing properties, coating corrosion resistance, coating color specifications and film adhesion properties are noteworthy. Additives can provide coating in-service sensing characteristics that offer alerts for the application of specific maintenance protocols based on changes in the coating. Additives that can participate in modifying the applied coating's physical properties triggered by environmental and substrate changes represent one of the outstanding challenges for additive development.

Specifically, nano-minerals (e.g., clays) with functional surface coatings can serve as sensors for changes in the chemical composition of the film. Color and noncolor reactions of pH-sensitive dyes fixed on nano-scale clays can signal film chemical changes, including corrosion of substrates that are in intimate contact with the coating film. The bonding of contaminants by coating additive components resulting in an observable, film-responsive behavior in the contaminated area serves to direct maintenance protocols for numerous application substrates. Additives also contribute functional properties to organically conductive coatings, intelligent pigments and coatings for storing information.

As these outcomes continue to evolve, the realization of decreased coating life-cycle costs, improved production efficiency, improved application performance and reduced maintenance costs represent the primary benefits sought through these developments.

Additives' Negative Side Effects

There are two major perspectives that may be considered regarding the negative side effects of additives on a coating. One consideration is the impact an additive can have while still a component of the bulk coating or the applied film. Although an additive is included in a coating formulation for a well-defined purpose, there are very few instances in which the additive does not participate in more than one chemical or physical role in the coating.

The negative side effects arise when the additive participates in interactions with other formulation components or external substances that contaminate the coating in a manner that promotes the growth of bio-organisms, causing the formation of coating defects or reducing the ability of the additive to serve efficiently in its intended role.

Another consideration is the negative side effect of an additive when it leaves the coating by leaching, evaporation or extraction. If the additive's physicochemical properties and toxicity inherently pose a potential risk to bio-organisms in the surrounding environment, then it not only reduces the coating's performance, but it presents a more serious concern for inappropriate contamination of the environment. For example, the application of certain types of antifoulants used in coating ship and boat hulls to prevent the growth of fouling organisms function as effective biocides. By their nature, these substances are toxic to living bio-organisms.

Surface-Conditioner Additives

Surface-conditioner additives are typically molecular or micro-phase chemical agents, which include fine particle-size wax, that can be introduced into a coating formulation to impart improved mechanical, optical and electrical surface properties to the applied coating film. The coating's scratch and mar resistance, anti-blocking properties, and water-repellant properties can all be enhanced utilizing these additives.

The use of these additives in coil coatings, powder coatings and particularly on wood substrates brings improved scratch and abrasion resistance, as well as anti-blocking and slip properties.