Reducing the drying time and decreasing the curing temperature are possible ways to improve the productivity and reduce costs. Enhancing the cross linking or polymerization of the resins may strengthen the dry film and offer better quality coatings. All formulators want to save time, energy and money to reduce the cost and enhance the quality of their coatings. Some of these goals can be achieved by using a catalyst. But playing a crucial role in the polymerization, the catalyst will not only affect the reaction rate, it will also have an influence on many other properties such as the adhesion, gloss, chemical resistance or shelf life.
But what exactly are catalysts in coatings?
What are Catalysts?
Nowadays, in many coatings, crosslinking reaction will not occur without the use of a catalyst. Or if it occurs, the kinetic is so low that the film forming reaction takes a long time.
A catalyst can be defined as a substance that initiates a chemical reaction making it able to proceed under modified rate. Unlike other reagents, catalyst is not consumed by this reaction. So, it may participate in multiple chemical reactions. Due to its presence, the catalyzed reaction will have a lower rate limiting free energy of activation than the corresponding non-catalyzed reaction, resulting in a higher reaction rate under the same conditions. As a consequence, using a catalyst can help in accelerating the crosslinking reaction, or reducing the curing temperature.
In other words: when the reaction between A and B requires a certain amount of energy, using a catalyst will reduce this amount.
- Under the same curing conditions, it will accelerate the reaction, and as a consequence, increase the cross linking rate.
- As the catalyzed reaction requires less energy, to obtain the same cross-linking rate as the non-catalyzed reaction, it is possible to reduce the curing time or curing temperature.
The Need for Catalysts
Many coating systems such as high solids, specific waterborne, urethane, amino systems and other 2 components require a high reactivity, low viscosity resins and crosslinkers to achieve a perfect curing, especially in the fields of industrial coatings, automotive or also coil.
Catalysts can help to convert these systems into chemically resistant and high
performance coatings at reduced cure temperatures and meet eco-friendly
Polyurethanes, acrylics, alkyds, epoxies and polyesters with reactive functional groups, such as hydroxyl, carbamate or amide can be reacted with various crosslinkers. The selection of the proper catalyst will enhance the crosslinking reaction.
Catalyst can be used either in waterborne, solventborne or even powder coatings, as long as their delivery forms fit your paint system characteristics.