Evonik's Superwetter Products Improve Flow and Spreading

Evonik Operations GmbH's superwetter product group, which has been on the market for several years, consists of the following products: DYNOL™ 604, DYNOL™ 607, DYNOL™ 360, DYNOL™ 800, DYNOL™ 810, DYNOL™ 960 and DYNOL™ 980. With the exception of the last two products, none of the products in the portfolio contain siloxane. DYNOL™ 360 provides benefits in water-based systems by reducing MFFT (minimum film formation temperature) and contributing to coalescence. Designed specifically to provide wetting on surfaces that are difficult to wet (such as plastics and contaminated metals), these products can also be used to support flow and spread in both water and solvent-based coating systems. This characteristic generates particular interest especially in automotive coatings. Automobile manufacturers are constantly seeking new ways to respond to their customers' continuously changing demands and to improve the appearance of their vehicles. As shown in Figure 1, our superwetter products provide both low dynamic surface tension (DST) and low equilibrium surface tension (EST). In this way, they offer advantages over fluorine-based surface active additives (fluorosurfactants) or conventional siloxane-containing surface additives. The ability to reduce both equilibrium surface tension and dynamic surface tension is what makes our superwetter products suitable for improving flow and spread. This article focuses on the performance and effects of our superwetter products not only in the automotive coatings in which they are used, but also in all coating layers. [caption id="attachment_104506" align="aligncenter"] Figure 1. Positioning of Evonik Superwetter products[/caption]   The combination of the ability to reduce both dynamic (DST) and equilibrium surface tension (EST) also helps prevent what is known as telegraphing (or shadowing), that is, the visibility of wipe or sand marks in the top layer of the coating system.

With our superwetter products, we offer OEM manufacturers the opportunity to meet their increasingly growing demands to reduce long and short wavelength (LW and SW) values in paint. As shown in Figure 2, particularly DYNOL™ 960 and DYNOL™ 800 are effective in reducing long and short wavelength values in 2K PE clear coat applied over water-based base coat. In this experiment, the base coat thickness is approximately 12 microns and the clear coat thickness is approximately 40 microns. Another important point to note is that the products effectively assist in reducing clear coat layer thickness while still providing excellent flow and spread.

The same effect is observed when additives are added to the clear coat; it ensures surface wetting, increasing flow and spread. It enables the formulator to achieve perfect long and short wavelength values even in lower layer thicknesses. Figure 3 shows the results obtained in 1K acrylic clear coat at a layer thickness of 35 microns. As shown, DYNOL™ 980 very effectively improves flow and spread. [caption id="attachment_104507" align="aligncenter"] Figure 2. Effect of superwetter on LW and SW in water-based base coat (2K PE clear coat)[/caption]   [caption id="attachment_104508" align="aligncenter"] Figure 3. Effects of wetting agents on SW and LW in 1K Acrylic topcoat[/caption]   The use of superwetter is a very effective way to improve flow and spread in solvent-based coatings even at very thin layer thicknesses. Superwetter products can be added to either base or clear topcoat. In both cases, formula developers will observe improvement.   Author: Jos Van Oosterwijk Application Technical Director Automotive and Transportation Coatings Evonik   Compiled by: Duygu Özgün Business Manager Evonik