Alkyl Phenol Ethoxylates (APEO) surfactants have been used in paints, coatings, inks, and adhesives for years. They are slow to biodegrade, toxic to aquatic life, and are an endocrine disruptor to humans. In recent years the EU and many countries have started to regulate and restrict the use of common APEOs like nonyl phenol ethoxylate (NPE) and octyl phenol ethoxylate (OPE) because of the extreme risk they pose to the environment and human health. While there still isn't a ban in the US on these chemicals there is a significant demand by consumers for products that are APEO free and it would seem that tighter regulation is in the near future. This has left formulators in the coatings, inks, and adhesives industries looking for alternatives to NPE and OPE that can match performance without having a negative impact on the coating or manufacturing process.
NOVELUTION - An Alternative to APEO
In response to the demand for APEO alternatives Sasol, a global leader in fatty alcohols, has released a line of nonionic surfactants called NOVELUTION. These alcohol ethoxylates are specifically designed to replace NPE and OPE in waterborne architectural coatings and latex paints as a wetting agent for pigments. One of the biggest challenges in replacing NPE and OPE is finding a surfactant that offers similar or improved performance while not having to alter manufacturing processes or the formulation. Sasol put NOVELUTION to the test against an APEO, Anionic, and acetylene diol surfactant in a water-based white flat acrylic latex paint formulation to show that similar and sometimes improved results can be achieved using NOVELUTION as a replacement for APEO without dramatically altering the formulation or manufacturing processes.
The formulation below is a white flat interior paint with a PVC of 50% and was used for all testing. The only changes made to the formulation were the surfactant (wetting agent). Associative thickeners were used and the concentration of the surfactant was held constant at 3 lbs per 100 gallons or 0.25% by weight for each formulation.
A comparison of the test formulations general properties including viscosity, opacity, and gloss are compared below. From a glance we can see that NOVELUTION provides similar and sometimes even improved properties when compared to an APEO surfactant.
A viscosity of 100 KU was targeted. Viscosity was measured after initial formulation (I) and again after 12 hours (ON) as it is common for viscosity to continue to build after initial formulation. One of the common issues faced when formulating a paint or coating is finding the appropriate balance of thickener and surfactant to hit your target viscosity and stay within viscosity specifications overtime. We can see from the graph below that NOVELUTION 390 offers the least amount of viscosity change of any of the tested surfactants and that most of the NOVELUTION grades offer an acceptable change in viscosity over time.
Significant Increases in opacity, which is preferred in flat finises, were achieved when comparing NOVELUTION surfactants to an APEO surfactant.
Color Strength and Color Acceptance
Perhaps the most important factor when choosing a wetting agent for pigments is how the surfactant will effect color strength and color acceptance (rub resistance). Again, Sasol put NOVELUTION to the test against an APEO surfactant and other common wetting agents. The titanium dioxide in the test formulation was replaced with four different pigments; a pthalo blue, red oxide, lamp black, magenta, and organic yellow. The APEO surfactant formulation was used as the standard for color strength and rub-up testing was performed 12 hours post application to check color acceptance.
NOVELUTION 3307 and 3505 are the best choice for matching color strength with APEO. Both of these grades and NOVELUTION 390 showed improvements in color acceptance.
NOVELUTION 390, 350, and 3307 all outperformed APEO in color strength and color acceptance.
All of the NOVELUTION grades provided better color acceptance than APEO and similar if not better color strength. NOVELUTION 390, 350 and 330 are all recommended as excellent choices for this pigment.
NOVELUTION 330 and 390 showed very similar color strength compared to the APEO. Both grades were far superior in terms of color acceptance.
This is the only pigment where APEO outperformed NOVELUTION on color acceptance. NOVELUTION 330 and 390 are very similar to APEO in terms of color strength and only moderately outperformed on color acceptance.
Summary & Conclusion
Replacing APEO in coating and paint formulations has become necessary for many manufacturers who ship products to Europe or who wish to stay ahead of coming regulations in the US. NOVELUTION alcohol ethoxylates are nonionic surfactants that are APEO free and have shown to match the performance of NPE and OPE without having a negative impact to coating properties. NOVELUTION 390 provides excellent color strength and color acceptance with all of the tested pigments and is recommended as a universal replacement for APEO.