Solus™: A New Solution for Wood Coating Formulations

What Ingredients Are Used in Wood Coating Formulations?

While waterborne wood coating formulations are increasing in terms of availability and demand, they are more frequently used in paint applications. For clear wood finishes meant to highlight the aesthetic of wood, solventborne wood coating formulations still predominate the market today due to the performance consistency they offer. Solventborne coating formulations consist of resins, solvents, and additives.

In a basic sense, resins are responsible for binding ingredients and forming tough films on surfaces upon curing. Solvents help dissolve formulation ingredients into a homogeneous solution at a viscosity necessary for applying the coating. While accounting for the least weight in formulations, additives provide critical functionality and modification of physical properties in coating formulations that tailor them for specific applications. In some cases, selecting the appropriate additives can significantly increase the value and overall performance of wood coating formulations.

Solus™ Wood Coating Additives

The Eastman Chemical Company has developed Solus™, a new brand of industrial performance additives designed to provide wood coating formulators the performance and versatility they need to create lasting, visually appealing formulations. These additives, made from cellulose, provide a host of functions to several types of wood coating formulations that improve durability, enhance aesthetics, and increase application productivity. A few key functions that distinguish Solus™ from other wood coating additives are listed below.

•    Resistance to yellowing and weathering
•    Faster early-cure hardness development
•    Increased control of gloss

Solus™ provides several benefits in different kinds of wood coating systems, including lacquers, polyurethane finishes, conversion varnishes, and UV-cured finishes. Performance data highlighting these benefits is presented below.

Early-Cure Hardness Development

Acrylic urethane wood coatings are some of the highest-performing options on the market for protecting and beautifying wood products such as furniture and cabinetry. These two-component (2K) systems, which consist of cross-linked acrylic polyol–isocyanate polyurethane chemistry, are typically soft and can create blocking issues and delay polishing steps due to extended drying times. When Solus™ additives are used to replace a portion of acrylic polyol content in these 2K systems, early-hardness development is significantly increased, as shown below. This is due to the rapid rise in formulation viscosity that Solus™ initiates upon curing. In the long term, Solus™ also helps improve coating hardness and durability.

Gloss Control

In all coating applications, Solus™ helps improve flow and leveling properties that reduce the incidence of visual defects that impact visual quality. As such, Solus™ helps increase the gloss of these coating formulations. It also helps improve the productivity of applying wood coatings by making polishing steps more efficient. The early hardness development described above helps reduce the number of polishing steps required to achieve higher gloss, which are labor- and time-intensive processes. Below, 20° and 60° gloss measurements were made using wood coatings with and without Solus™. As seen, the formulations with Solus™ achieved higher gloss measurements in fewer polishing steps than those without it.

For wood coating formulations that require lower gloss, silica matting agents are typically used. Solus™ also helps disperse silica more effectively due to its rheology-modifying properties. In the chart below, an acrylic polyurethane wood coating formulation containing silica matting agents was prepared with and without Solus™. Gloss measurements of 60°  were made, and the results indicate that significantly lower gloss was achieved with even low levels of Solus™ present in the formulation.

Solus™ Grade Selection

Many Solus™ grades exist to allow formulators to select the best choice that suits each formulation. Specifications that are important to consider include relative viscosity, compatibility in solvents and with other formulation ingredients, orange peel avoidance, and dry time improvements. Some grades are also designed for better reflowability, allowing thermoplastic systems to be reheated to remove scratches. For a full list of Solus™ additives, click here. Solus™ additives designed for wood coatings are contained within the 5000 series. We highly recommend reaching out to one of our technical product experts for assistance in selecting the right grade. To discuss your formulation and receive samples with our experts, click the link below.