The Waterborne Symposium 2025

Co-Authors:
Juliane P. Santos, Larissa C. C. de Almeida, Maira V. de Carvalho, Michael Praw

Abstract
"The emulsification of resins used in solvent-based coatings into water is a crucial strategy for developing environmentally friendlier water-based coatings. Among the various resins used in solvent-based coatings, alkyd resins stand out due to their partial renewability and extensive use in decorative and protective coatings. They offer excellent adhesion to a variety of substrates, high gloss, durability, and resistance to water, chemicals, heat, and solvents. However, due to environmental and GHS concerns, there is a trend towards emulsifying these polymers with emulsifiers to create stable oil-in-water emulsions for water-based formulations.

Long-in-oil alkyd resins with viscosities ranging from 5000 to 15000 cP at the emulsification temperature are typically emulsified using the phase inversion methodology with low shear mixing equipment. However, emulsifying higher viscosity resins, such as medium-in-oil alkyd resins, presents more challenges.

This work focuses on developing a special solvent and optimizing emulsifier compositions to reduce the viscosity of medium-in-oil alkyd resins, enabling their emulsification through phase inversion using low shear mixing equipment, and producing emulsions with particle size below 400 nm.

The prototype of an environmentally friendly solvent, designed for having Hansen Solubility Parameters (HSP) close to the ones of the alkyd resins, effectively decreases the viscosity of medium-in-oil alkyd resin at 80°C, the emulsification temperature, as confirmed by rheological measurements. A small amount (5 wt%) of this solvent reduced the viscosity by approximately 60%.

The emulsifier compositions include a special nonionic emulsifier designed for alkyd resin emulsification and a conventional anionic emulsifier. Interfacial tension evaluation between a model oil phase containing the emulsifier composition and water was used to select the most effective emulsifier compositions for reducing the interfacial tension, crucial for successful emulsification.

The study also explored the effects of two bases, sodium hydroxide and triethylamine, used for neutralizing the carboxylic groups of the resin, and the conventional anionic surfactant. The interfacial tension results indicated that compositions rich in the nonionic emulsifier could reduce the interfacial tension at 40°C from 18 mN/m to nearly 0 mN/m.

Based on the interfacial tension results, three compositions rich in the nonionic emulsifier were evaluated with each base. The alkyd emulsions neutralized with sodium hydroxide had a solid content of about 49 wt%, particle sizes ranging from 200 to 230 nm, and a zeta potential of around -40 mV. These emulsions, formulated with a drier recommended for water-based formulations, had a drying time close to 5 hours. The stable emulsions neutralized with triethylamine had a solid content of about 49 wt%, particle sizes ranging from 240 to 320 nm, a zeta potential of around -50 mV, and a drying time ranging between 3 to 4 hours.

The strategies developed in this work are also being applied to the emulsification of other resins, beyond alkyd resins. This includes important classes of resins such as epoxy resins. "

Abstract

Silicone materials are increasingly valued in the paint and coatings industry because of their advantageous properties of high temperature stability, moisture resistance coupled with breathability, and superior resistance to weathering. Although traditionally processed in volatile organic solvents, sustainability commitments and customer demand are driving a transition to waterborne approaches. At present, waterborne silicone-containing binders are still uncommon because they are notoriously difficult to prepare. We recently presented the development of a novel waterborne silicone-organo copolymer binder for industrial coatings. These copolymer dispersions have nearly zero VOC. When used in conjunction with a curing agent, they provide durable crosslinked film coatings on metal surfaces, with excellent hardness, solvent resistance and weatherability. They are excellent binders for a variety of organic and inorganic pigments. Here we discuss their outstanding stability to extended accelerated weathering conditions when used in conjunction with pigments

Abstract

Recent popularity of thin aluminum flakes for chrome replacement has stimulated development activities to push the limits of color and performance of these pigments in waterbased systems.  This presentation will explore the multiple options for surface treatments of these aluminum flakes and the effect these treatments have on final color, sparkle, opacity, gassing, dispersion, shear and chemical resistance in both interior and exterior coatings.  Visual assessment and instrumental analysis of coatings containing these pigments will be discussed.  Also addressed will be the options available for pigment carrier and delivery form, such as paste, powder and solvent free granules, designed to perform in the most demanding low VOC coating systems.  Proper dispersion and formulating practices will also be explored.  

Co-Authors: Dr. Peter Greenwood, Global Technical Development Manager, Inorganic Specialties, Nouryon

Abstract

One of the primary challenges for low-VOC coatings is achieving smooth film formation, acceptable block resistance, and adequate film hardness. Block resistance depends on both bulk and surface properties. This article examines the effects of adding colloidal silica on the block resistance of acrylic paint. Colloidal silica enhances the hardness and durability of coatings, improving their resistance to abrasion, scratches, and other properties. Additionally, it contributes to smoother film formation and better weather resistance, making the coating less likely to stick to itself when two painted surfaces come into contact.

Co-Author:
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Abstract

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."

Abstract

Grinding pigments and fillers using cowles dissolver is a standard practice for breaking down agglomerates and aggregates into primary particles during the production of waterborne paints, especially architectural paints. Serrated disc introduced at the appropriate peripheral speed forces a specific flow in the vessel, which causes the agglomerated particles to rub against each other and collide with each other. The wetting and dispersing additive introduced to this process is supposed to build a double electrical layer according to the DVLO theory, but this is only a theory that has little to do with practice. Of course, the theory of wetting, significant zeta potential and other properties of dispersing additives are true, but their correct use in mill-base formulations and further influence on the parameters of the grinding process itself and the parameters of the paints depends solely on the effectively found dose and balance between mill-base concentration allowing grinding at low viscosity and maximum solids loading, without adding any rheology additives during grinding. The paper discusses examples of grinding of various pigments and fillers used in architectural paints and discusses how to properly balance the ingredients and the grinding process to achieve the lowest possible viscosity, low energy consumption and donut-shaped flow, without using rheological additives that prevent proper grinding and breaking down of pigments and fillers into primary particles. It also presents how to properly control the mill-base slurries obtained after the grinding process and how to combine them with latex polymer dispersions in the let-down process to obtain stable architectural paints.

Co-Authors:
Alann O. P. Bragatto, Suzy S. Alves, Bruno S. Dario

Abstract
"The selection of wetting and dispersing agents in pigment concentrate formulations is a non-trivial task. The vast array of available products and technologies, coupled with a frequent lack of adequate technical information, makes the formulator’s job extensive, intricate, time-consuming, and inefficient due the lack of rationalization in the use of these additives. These factors created a barrier to innovative and more sustainable products since the work required to screen new additives became an art instead of a science.
The present study aims to demonstrate how the use, development, and implementation of physicochemical methodologies, combined with digital tools and high throughput screening, can generate highly useful data for formulators in the additive selection and formula optimization process, making it faster, smarter, and more efficient.
The first and most comprehensive part of the work illustrates how physicochemical techniques and parameters applied to surfactants can be utilized in the selection of wetting and dispersing agents. It is demonstrated the correlation between static surface tension, dynamic surface tension, wetting time, contact angle, and free adsorption energy with performance and process properties in pigment concentrate formulations, such as deflocculation curves, process time, tinting strength, rub-out, and stability.
The second part of the work is focused on the development of a method to create adsorption isotherms and on their use. This data is extremely valuable as it allows for comparisons between additives from different technologies even when the chemical structure is unknown. The study demonstrated how the curves and parameters obtained from this technique can help formulators understand which additive has higher affinity for a given pigment, aiding in the selection of dispersing agents with higher potential to provide good performance and longer stability. Additionally, this methodology helped understanding the versatility of the additive, clarifying whether the same molecule could be used with different types of pigments. The results from the adsorption isotherms were correlated with the stability, tinting strength, and rub-out of the pigment concentrates.
The final part of the work aims to apply Hansen solubility parameters (HSP) to evaluate the compatibility of wetting or dispersing agents with pigments. The current focus is on using high throughput screening to determine the HSP values of a variety of wetting and dispersing agents – such as surfactants and polymerics with or without charges. After the parameters of the additives and the pigments of interest are obtained, formulators could use these data to simulate the interaction between the additive and the pigment, enabling the selection of the most promising candidates for experimental evaluation. The last goal of the work is to provide initial data on the HSP parameters determination and compatibility simulations to then correlate with experimental performance data of pigment concentrates, such as tinting strength, rub-out, and stability. Once the correlation is proven, this methodology will allow a quick determination of parameters without requiring knowledge of product’s composition and will aid the development of better coating formulation."

Co-Author: James Rawlins

Abstract

The effective mitigation of corrosion through the application of protective coatings is of paramount importance, impacting both economic and safety outcomes.  Historically, the detection of coating failure and the ensuing corrosion has largely depended on visual inspection and destructive testing methods, which do not adequately predict onset or service lifetimes.  Current methods also lack correlation to specific polymer characteristics that govern corrosion resistance.  This research introduces a novel, nondestructive method that combines Electrochemical Frequency Modulation (EFM) and Confocal Laser Scanning Microscopy (CLSM).  By studying epoxy-amine coatings through a range of tailored glass transition temperatures (Tgs), ranging from high (269 °C) to sub-ambient (4 °C), these research results work contributes to the predictive modeling of coating lifetimes and advances our understanding of the relationship between polymer properties and performance in mitigating corrosion.
Previously, we have shown that the more hydrophilic a crosslinker was, the faster micro-blister formation around a predefined defect occurred.  Micro-blister with delay times varied from 47.5 to 5.5 hours for coatings with increasing hydrophilicity.¹  These results showed that a coating with a Dry Film Thickness (DFT) of 45 μm reduced micro-blistering and exhibited slower corrosion rates compared to the same materials at 5 μm DFT. These results emphasized the role of mechanical beam integrity and corrosion resistance and confirmed that coatings that limit swelling in water and delay physical state changes during immersion were dramatically better at reducing corrosion activity. Example, a coating designed with a high glass transition temperature (Tg) of 269 °C showed less than 3% swelling under all conditions and preserved mechanical properties, including a storage modulus of 2416 MPa, after exposure to corrosive environments. The results indicate that strengthening the mechanical robustness and reduced swelling and physical state changes (such as from glassy to rubbery) for a given coating during exposure are crucial for corrosion control and substrate protection.

Co-Authors: Roger Mouhanna and Laurent Desfontaines

Abstract

Fluoro resins, commonly used in outdoor coatings, offer exceptional weather resistance, durability, and stain resistance. They help maintain the aesthetic appearance of coated surfaces for extended periods, reducing the need for frequent maintenance and repainting.
However, the use of fluoro resins is increasingly regulated due to concerns about PFAS substances. Regulatory bodies have implemented stricter controls on the manufacture, use, and disposal of PFAS, due to their persistence in the environment and the potential health risks. These regulations aim to minimize the release of harmful substances and encourage the development of safer alternatives.
Hybrid resins, combining inorganic polysiloxane with organic acrylic or polyurethane components, offer a compelling alternative to traditional fluoro resins for outdoor coatings. These advanced resins provide superior long-term protection and aesthetic appeal, significantly reducing maintenance costs. Available in various water-based formulations, including 1K and 2K systems, they meet diverse application needs and regulatory requirements, making them a versatile and effective choice for outdoor coatings. In the frame of this work, we will illustrate these benefits with specific examples and case studies, demonstrating the superior performance and compliance of these hybrid resins with current regulations.

Abstract

"Waterborne polyurethane dispersions (PUDs) are renowned for their exceptional film-forming ability, toughness, and flexibility. However, they are often challenged by poor water resistance and higher production costs. Polyurethane/acrylic hybrid resins offer a balanced, cost-effective solution, combining the strengths of both PUDs and acrylics. These hybrid systems provide enhanced mechanical properties alongside superior water and chemical resistance, making them an ideal choice for high-performance coatings.

This presentation highlights the development of an innovative polyurethane/acrylic hybrid waterborne resin designed to meet both environmental and high-performance requirements. Synthesized in the absence of added solvents, this resin allows for coatings to be formulated at low VOC levels while still offering a balance of hardness, flexibility, and favorable coalescence properties, making it an ideal binder for applications with stringent environmental constraints. Free from amines, the resin also addresses concerns over amine-related issues such as migration and yellowing, while enhancing overall formulation stability. The resin also exhibits good solvent resistance and excellent adhesion to a wide variety of substrates, including metals, plastics, and woods, making it suitable for diverse industrial applications."

Abstract

The paint and coating market for kitchen cabinets, trim, and doors focuses on products designed to enhance the appearance and durability of wood and other commonly used materials. These coatings must meet stringent performance standards, including early block resistance, surfactant leaching resistance, body lotion resistance, and scrub resistance. Traditionally, per- and polyfluoroalkyl substances (PFAS) additives have been used to improve block resistance. However, due to increasing regulatory restrictions on these hazardous substances, there is a growing need for alternative solutions. This paper explores the current market landscape for kitchen cabinets, trim, and doors, and discusses our recent sustainability efforts to develop innovative waterborne acrylic latex binders specifically designed for these applications. We will also discuss general strategies to enhance key properties, including early block resistance, surfactant leaching resistance, and body lotion resistance.

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Celebrate and empower at the 2025 Waterborne Symposium's Women in Science Networking Event! Please join us for our Women in Science Networking event for some cocktails and an intimate discussion about these topics with our plenary speaker, Victoria Scarborough.

We are delighted to host this special occasion dedicated to honoring and supporting women in STEM. Join us for an extraordinary opportunity to connect with inspiring individuals, foster meaningful collaborations, and contribute to the advancement of women in science and technology. Let's come together to share experiences, build a supportive network, and pave the way for a brighter future in the world of science. Don't miss this empowering event! #2024WaterborneSymposium #WomenInScience #STEMNetworking