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Reformulating Latex Paint with Capstone™

Low-VOC & VOC-Free Latex Paints

Once considered inferior to solvent-based coatings, water-based coatings have seen rapid technological improvements and increased demand over the last four decades. This is largely due to tighter regulations regarding clean-air standards, especially within the architectural paint market. While these technological advancements have allowed latex paints to rival the performance of solvent-based paints, they have also caused formulation costs to rise. Thankfully, the increased cost of formulating a latex-based paint can be mitigated using Capstone™ surfactants. 

What is Capstone?

Capstone™ is a line of VOC- and APEO-free fluorinated surface-active agents (surfactants) that are extremely effective nonionic and anionic wetting agents in water-based paint formulations. Capstone™ surfactants are available in anionic, amphoteric, and nonionic options. 

How Can Capstone™ Reduce Paint Formulation Cost?

When incorporated into latex paint formulations at a very low level, Capstone™ reduces or eliminates the need for pigment- and surface-wetting agents and other surfactants. This is because Capstone™ is an extremely effective wetting agent. When added to water-based systems at a typical concentration between 0.01% and 0.05%, surface tension is reduced to as low as 17 dynes/cm. By replacing traditional surfactants with Capstone™, approximately threefold to tenfold cost savings can be realized while achieving superior substrate wetting. The diagram below illustrates an example of this, where blends of common surfactants are made using either a hydrocarbon surfactant or Capstone™ FS-31. As seen, for the same cost, Capstone™ FS-31 reduces surface tension to a far greater degree than the hydrocarbon surfactant. As such, a greater surface tension reduction can be achieved using Capstone™ while potentially reducing the need for other surfactants, depending on the target surface tension.

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Furthermore, Capstone™ adds antiblocking and dirt pickup resistance properties, reducing the need for other additives to achieve this functionality. In addition, some grades of Capstone™ provide defoaming properties, decreasing defoaming additives and offering even further cost savings for latex-based paint formulations.

Guidelines for Reformulating Paints with Capstone™ 

Because waterborne paint formulations can vary and must satisfy a range of performance needs, there is no simple one-size-fits-all solution to reformulating with Capstone™ to realize cost savings for latex-based paints. However, to better understand how Capstone™ works in the paint formulation process, the table below provides some general guidelines.

Capstone™ can be added in the grind phase to eliminate the need for a pigment wetting agent and a defoamer in paints. It can also be added during the letdown phase to reduce surface tension and improve leveling, dirt pickup resistance, and antiblocking properties. Selecting the appropriate Capstone™ grade depends on the desired functionality and the phase at which it will be added to the paint. The image below highlights common Capstone™ grades and their primary functionalities. 

Capstone™ for Pigment Wetting in Paints

Pigment-wetting agents are added during the grind phase and are intended to help replace the air surrounding the pigment particles with the carrier medium, typically water. Capstone™ FS-30 and Capstone™ FS-31 are nonionic surfactants that are APEO free, VOC free, and nonflammable. These can be added in very small amounts during the grind phase to improve pigment wetting, eliminating the need for other wetting aids. For more information on this topic, check out this article. Capstone™ FS-30 and FS-31 also provide high surface tension reduction, which is essential for improving coverage on substrates. 

Capstone™ for Leveling & Anti-Blocking of Paints

Water-based paints often have issues wetting out low–surface energy surfaces, resulting in a high contact angle. This can cause poor adhesion and lead to surface defects, such as orange peel, pinholes, and cratering. This may especially be a problem when a high-gloss finish is required. A leveling agent is typically required to ensure a defect-free finish. Capstone™ FS-61 and Capstone™ FS-63 are anionic surfactants that are powerful wetting agents and leveling agents that can be added to latex paint formulations during the letdown phase. Additionally, Capstone™ FS-61 and FS-63 grades are APEO free. Comparing the two, FS-61 is VOC free, and FS-63 is based on isopropanol but has a higher solids content. FS-63 can improve surface tension reduction, oil repellency, and easy-clean properties. An added benefit to using Capstone™ as a leveling aid is that it also delivers excellent antiblocking properties and eliminates the need for waxes and other common antiblocking additives in the formulation. 

Capstone™ for Paint Dirt Pick-Up Resistance

Latex paints used in architectural applications tend to pick up dirt and oily stains over time. Adding Capstone™ FS-81, an APEO-free nonionic surfactant, in low-sheen paints and waterborne coatings improves the cleanability of oil-based stains and improves oil and dirt repellency. Additionally, Capstone™ FS-81 does not interfere with paint recoat adhesion or create water repellency. The graph below illustrates the increase in the contact angle of oil on a painted surface when Capstone™ FS-81 is added to the formulation. 

Summary & Conclusion

The demand for water-based paints and coatings continues to climb as environmental regulations tighten regarding VOCs and clean air. Coating manufacturers need to maximize the performance of their latex-based paint formulations while minimizing production costs. Capstone™ fluorosurfactants are superior wetting agents that reduce surface tension much greater than traditional surfactants. They are recommended as a cost-saving replacement for alcohol ethoxylates, APEO, and other common wetting agents. Additionally, adding Capstone™ to latex paint formulations eliminates the need for several other additives, including defoamers, leveling agents, pigment-wetting agents, and antiblocking aids. Contact us below to have our product experts schedule time to discuss your paint application and recommend Capstone™ samples for you. 

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