The Waterborne Symposium 2025

Abstract
"Microbial contamination of paint and coating products can have adverse effects on the product, such as offensive odors, discoloration, or viscosity changes. Although preservatives (biocides) are available as additives to prevent the proliferation of microbial growth, manufacturing controls should be implemented to prevent the contamination in the final product. Robust cleaning processes and other manufacturing controls can be designed to provide microbial control for equipment product-contact surfaces, preventing microbial contamination of the product. A thorough understanding of the raw materials, formulation, manufacturing process, and other manufacturing characteristics will help identify potential sources of contamination and guide the development of the contamination controls needed in manufacturing. Designing processes that can address both cross-contamination and microbial contamination on equipment surfaces would be beneficial for production efficiencies while producing quality products with a longer shelf life.

This presentation proposes a holistic approach for controlling microbial contamination through the implementation of effective cleaning processes and other cleaning-associated activities. Current regulatory trends limit manufacturers to the use of certain preservatives, which may not be as effective as some of the legacy additives used in the past. This promotes a need for the implementation of preventive controls for microbial contamination introduced during the process and less reliance on the use of preservatives in the product. A cleaning process can be designed through a formal risk assessment process where critical process controls are implemented to mitigate microbial contamination risks identified that may impact a product’s critical quality attributes. There are multiple factors that play into the design of an effective and efficient cleaning process: control of water and raw material quality, selection of adequate cleaning agents, equipment storage conditions, equipment preventative maintenance procedures, and the critical controls of the cleaning process itself. When adequate controls are implemented, the cleaning process and other preventive measures discussed in this presentation can control microbial contamination on equipment and, subsequently, the final product."

Abstract

Agricultural biomass raw materials are plentiful and a sustainable source of raw materials. Importantly, the physical and chemical conversion of agricultural residues to useful organic building blocks is often limited in utility by lower than preferred physical and chemical conversion efficiency. We chemically modified high purity cellulose with additional natural products to explore the utility of organic-solvent soluble cellulose based polymers in a single reaction step. The resulting biobased materials were formulated into practical surface coatings and were evaluated for material characteristics, formulation variables, solubility, film formation, and film performance. Each solvent based, waterborne, and powder coatings were produced and evaluated using the novel sustainable materials. Key parameters: solvent content versus time after application, optical clarity, film formation, solids content, rheological characteristics, and cursory thermoset testing for crosslink density were each compared with high performance petroleum based systems. The solvent based modified cellulosic formulations were further evaluated comparing rheology, film formation, wetting, adhesion, and optical clarity when formulated with conventional solvents (MEK and Toluene) with biomass derived VOC-exempt solvents with and without isocyanate crosslinkers. The formulation details and variables, the coatings characteristics, and the performance were each evaluated and compared to several commercial petroleum based coatings as we begin to understand the modified cellulosic-materials utility.

Co-Authors: Christin Jäger and Katja von Nessen

Abstract
"In the coating industry there is increasing demand for environmentally friendly and safe products driven by regulations such as reduction of VOCs and CO2 emissions and the replacement of critical raw materials. Bio-based raw materials have been found to be appropriate substitutes as they frequently exhibit a significantly lower carbon footprint, a better toxicological profile as well as the capability of biodegradation.

In this study, the performance of bio-based citrate esters as coalescing agents for an architectural paint formulation was investigated and the results were compared to market standards. Furthermore, the useability of xanthan gum as rheology modifier was studied and the performance was compared to cellulose thickeners (HEC, Hydroxylethycellulose) for the same application. Contrary to most of the classical coalescent agents, citrate esters are non-VOC and comply with the latest toxicological and environmental safety requirements: they are characterized by highly efficient solvation, low migration and non-VOC attributes. To showcase those features 2.4 wt% coalescent agent were incorporated into an architectural paint based on an acrylic binder. The deviations in properties of the dried paint were not significant among the tested coalescent agents. The study also revealed that the same dosage of xanthan gum leads to a low shear viscosity about 60% higher compared to cellulose thickeners. This effectively improves storage stability, due to the high stabilization of pigment particles, while leading to comparable levelling and sagging. High shear viscosity on the other hand is about 50% lower, which improves applicability. The versatility of xanthan gum is not limited to pigmented systems. It is possible to adjust the viscosity of clear coats, while maintaining transparency."