Additives belong to a broad and diffuse category of key components in a coating formulation. They comprise a small percentage of the coating formulation – their use level rarely exceeds 1 or 2%, and the total level of all additives in a formulation seldom exceeds 5% of the total product. Their impact, however, is significant as they contribute to the ease of manufacture, the stability of the coating in the package, ease of application, quality and appearance of the final film.
Additive function is almost always very specific in nature. Some additives are multi-purpose; for example, they may be important to the manufacturing process as well as to the coating’s performance. In recent years, more multi-purpose additives have been developed, thus allowing the use of fewer additives in many formulations. Occasionally the use of one additive will require the use of another to counter some undesirable effect of the first.
Some additives are proprietary products with highly specific functions that work well in some systems but cannot be used in others. In addition, because of the proprietary nature of many additives, their chemical composition is not disclosed. This can make general recommendations difficult as the lack of structural knowledge means that additive substitutions cannot be made on the basis of fundamental structural chemistry.
The focus on green technology, sustainability, nanotechnology, lower cost and safer products has led to the introduction of newer additives and chemistries. The industry demands that green additives perform the same or better than their traditional counterparts and that they combine performance, sustainability and efficiency along with lower cost. With a larger number of additives available for a particular problem, formulators can find themselves in trouble if the wrong additive is initially selected or added to alleviate or correct a problem. Correct additive selection is important to success, and such selection is made through vendor assistance or years of experience.
Additives are generally categorized by function rather than by chemical composition or physical type. Because the actual chemical composition of many additives is proprietary, a formulator may run into problems with chemical side reactions. It is important to consider the total additive package and to always seek recommendations from the manufacturer. Because of the changing technology within the industry driven by cost, VOC and other legislation, eco-friendly products and sustainability, many of today’s additives are multi-functional; some are also incorporated into polymeric backbones. These factors, in addition to nanotechnology, make it much more difficult to categorize additives by function.
Please note that there are a number of new nano-sized additives and biobased additives in the market today; their functions are varied and they tend to overlap the past traditional categories. For this reason we have included a number of these types under the Nanotechnology and Biobased sections.
The following is a brief description of many coating additives, along with some examples.
View The 2014 Additives Refrence Guide here in our June Digital Edition or on page 38 of the June Issue.