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:
.

Abstract