At a basic level, the drying process for water-borne coating systems involves water evaporation, coalescence, and solidification. How long this process takes determines when the coated substrate can be used, handled or recoated.
Many applications can benefit from faster drying, better block resistance, shortened handling times and/or enhanced flash rust resistance. Faster early performance characteristics enable increased productivity because the installer/contractor can better utilize their time and increase project load. Faster dry times also minimize site disruption and allow for a faster return to service for property owners and managers. In addition, accelerated drying time can lengthen the application period of a seasonally applied coating, which allows the installer/contractor to extend opportunities for exterior applications, increasing the number of projects they can complete as well as their annual revenue.
One method to accelerate the drying time is to use an ionically stabilized dispersion which is stabilized at an elevated pH plus a fast-set additive. As the coating system dries and volatile materials are lost, this type of additive builds cationic charge causing the coating to “set”, while also facilitating the remaining water transport through the film.
Accelerating Drying in Anionic Water-Borne Systems
Lubrizol explored and developed a novel, experimental fast-dry additive technology. In low-temperature testing, the new fast-dry additive showed early coalescence and early rain resistance at two hours dry time (9°C (48 ⁰F)) and 92% relative humidity with sporadic light rain) compared to benchmark and control materials. At 12 °C (55 ⁰F) and sporadic rain, the benchmark sample exhibited a thicker skin, but remained more fluid beneath compared to the fast-dry additive, which showed coalescence in the bulk of the material. In 24-hour testing at 7 °C (45 ⁰F) and 100% relative humidity, the new fast-dry additive proved to be demonstratively better than conventional technology.
This fast-dry additive was designed to improve the rate of cure and the drying schedules of many coating resin systems. Further testing and real-world applications have demonstrated that by incorporating it into coating systems, dry time can be reduced by 20-45% when compared to conventional technology. This performance benefit has the potential to extend the working season in exterior applications, reduce labor costs and can minimize early wash off due to unexpected rains.
Lubrizol's experimental additive is not a universal additive for all water-borne coatings but has shown to be effective when incorporated into coatings that utilize a resin containing some functionality. Typically, greater delineation in performance from unmodified conventional technology will be seen at lower application temperatures and humidity.
In addition to reduced dry time and an extended working season, the experimental additive formulates to low VOC by eliminating the need to use highly volatile (flammable) solvents and exhibits minimal odor when incorporated into coating systems. It is stable in compatible formulated coatings and does not impact physical properties for seamless production incorporation.
Contact us to learn more about this soon-to-come fast-dry additive for water-borne coating systems and how it can be used to enhance specific applications.
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