Performance Additives for Coatings and Concerns about VOCs
Legislation aimed at reducing air pollution through the emission of volatile organic compounds (VOCs) has significantly impacted many industries. For several years, Eastman cellulose esters have found widespread use in coating applications to improve performance and appearance.
Many formulators benefit from the fact that Eastman cellulose esters are naturally derived, a property that allows incorporating bio content into coatings. However, some cellulose ester grades with high molecular weights cause an increase in viscosity. This requires an offset by increasing the amount of solvent, which results in a level of VOCs higher than the legislated maximum values.
Solus™ 2100: Increased Performance and Low VOCs
Eastman cellulose esters are widely used in coating, ink, and adhesive applications as either binders or additives that provide the following key benefits:
Improved adhesion onto various substrates
Better leveling and flow properties
Higher abrasion and chemical resistance
Resistance to yellowing due to UV exposure
Faster drying times
Enhanced gloss
Eastman has developed a new additive specifically designed to provide the same benefits as cellulose ester coating additives but with the added advantage of lower viscosity. Like cellulose esters, Solus™ 2100 is also a naturally derived, low–molecular weight additive that is soluble in a wide variety of organic solvents. The combination of the high solubility and lower viscosity that Solus™ 2100 provides in formulations, however, can further reduce VOCs by requiring less solvent to maintain an adequate viscosity for application. A comparison between Eastman's CAB-551-0.01 additive versus Solus™ 2100 on viscosity is presented below.
Solus™ 2100 is also completely soluble in parachlorobenzotrifluoride (PCBTF), a VOC-exempt solvent. This enables it to be used to make low-VOC formulations.
Improvements to High Solids 2K Coatings Using Solus™ 2100
One of the specific applications in which Solus™ 2100 is used is high-solids, two-component thermoset coatings with low VOCs (420 g/L VOCs or lower). Often, low–molecular weight acrylic resins are used in these formulations and induce long drying times. In addition to keeping VOCs low through mechanisms described previously, Solus™ 2100 decreases dry time and increases polishability, sandability, and chemical and sag resistance. Below are data on dry time in an acrylic paint system that included Solus™ 2100 additive versus one that did not.
The visual quality of coatings is often a key performance factor, and Solus™ 2100 does not impair gloss or distinctness of image. A comparison was made between coating systems that included the Solus™ 2100 additive and those that did not to determine the effect of polishability:
These results indicate that the coating formulation that included Solus™ 2100 required fewer steps to achieve the desired gloss and appearance levels.
Summary
Regulatory changes to reduce VOCs in coating formulations require formulators to seek coating additives that provide performance benefits while maintaining a low viscosity that reduces solvent demand. Eastman Solus™ 2100 provides a perfect mix of improvements to two-component, high-solids coating formulations to increase drying speed, flow and leveling properties, and resistance to chemicals and abrasion while enhancing polishability and preserving visual quality. Additionally, Solus™ 2100 increases the sustainability of formulations by increasing bio content and lowering VOCs. Click below to request a sample for your formulation.
