VOC Emissions and Performance of a Novel Bio-Based Acrylic Polymer for Interior Paint Applications
By , , , , and , Dow
The drive towards sustainability and a more circular economy has become a pivotal strategy across the coatings industry. This shift has spurred initiatives to reduce carbon footprint emissions, utilize materials with extended lifespans, source from renewable feedstocks, and create safer products. In response, the first all-acrylic bio-based latex emulsion polymer tailored for the North American interior paint market has been developed. This next-generation commercial polymer offers numerous advantages over traditional fossil feedstock-based emulsions, including a competitive cost structure, bio-based carbon content exceeding 20%, and exceptionally low volatile organic compound (VOC) levels, all while maintaining performance characteristics associated with acrylic paints.
Beyond addressing bulk VOC concerns, the industry has seen increased scrutiny over the past decade regarding paint emissions post-application. This article explores seminal methodologies and volatile emission results of paints formulated with latexes derived from various feedstocks. It highlights the ultra-low emissions achieved with this new bio-acrylic polymer, representing a significant advancement toward more sustainable interior paint.
Introduction
The global coatings industry is undergoing a pivotal transformation, shifting from fossil- derived raw materials to more sustainable, renewable alternatives. This change is driven by the need to foster a more circular economy, minimize environmental impacts, reduce greenhouse gas emissions, and align with ever-changing health and regulatory standards.1
However, this movement is not the first paradigm shift the coatings industry has undergone as lowering the total VOC in wet paints has been a continued concern for raw material suppliers and paint manufacturers for several decades. In the 1940s, solventborne paints contained VOCs in concentrations as high as 700 g/L.2 With the emergence of latex paint in the 1950s, VOC was greatly reduced. Since that time, the Clean Air Act and the Clean Air Act Amendment have helped push that total VOC even lower.3 Agencies such as the California Air Resource Board (CARB) and certifications such as Blue Angel have led the paint industry toward near-zero VOC regimes. More recently, there has been growing concern and emphasis on indoor air quality (IAQ) and VOC emissions as paint dries over time. Measuring IAQ accurately is a complex challenge, and it has taken decades to develop the equipment, procedures, and expertise to collect, measure, and identify potential sources that can lead to poor IAQ.4 With a growing list of standards such as UL Green Guard5 and California Department of Public Health (CHPD) 01350,6 new innovations within the paint industry such as the transition away from fossil feedstock-derived materials will need to also uphold the increasingly stringent standards surrounding VOC and VOC emissions.
At its core, adopting bio-based coatings lies in their potential to reduce dependency on fossil resources and lower overall carbon footprints. Traditional coatings rely on fossil-based feedstocks and additives, which are increasingly scrutinized for their environmental and health impacts. Transitioning to renewable feedstocks can directly support greenhouse gas reduction strategies and respond to consumer and regulatory demands for safer, more sustainable materials that can be validated by third-party certifications.
Among the most promising advances is the development of bio-based acrylic polymer dispersions capable of matching, and in some cases surpassing, the dry-film performance of traditional fossil feedstock-based systems while also exhibiting superiority in low emissions. A newly developed bio-based acrylic binder represents a milestone in this journey. Beyond merely substituting fossil fuel inputs, the binder incorporates traceable biocarbon content into polymer emulsions, verified by established methodologies, and it delivers on three key sustainability goals:
- substantially reduced bulk and emitted VOCs compared to fossil feedstock-based control paints
- absence of intentionally added per- and polyfluoroalkyl substances (PFAS) or alkylphenol ethoxylates (APEO)
- approximately 27% bio-based carbon that can enable the U.S. Department of Agriculture (USDA) BioPreferred® certification of interior latex paints
This article presents a detailed technical evaluation of the new all-acrylic bio-based latex binder. This innovative dispersion not only preserves formulating latitude and dry-film performance but also achieves dramatically reduced levels of VOC emissions, both in bulk and during application, relative to standard fossil-based controls. The findings are grounded in comprehensive data which are provided in this article.
Experimental
Preparation of Bio-Based Paints
Paints with the new bio-based binder were made into both flat and semi-gloss formulations (see Tables 1 and 2). The starting point flat white formulation comprises 37% volume solids and 48% pigment volume concentration (PVC), while the semi-gloss formulation consists of 37% volume solids and 24% PVC.
Additionally, thickened binders of equivalent weight percent solids were made to determine emitted VOC contributions from just the binder versus those from the total paint formulation. The thickened binders were made by diluting with the appropriate amount of water and then modifying their rheology with an inorganic thickener which enables appropriate coat weights to be achieved without contributing to emitted VOCs.
Continue reading in the March-April issue of CoatingsTech