Pushing the boundaries to enable more and more challenging applications
Do you see developments that can increase the application possibilities for water-borne coatings?
Water-borne coatings face quite a few limitations and challenges due to the nature of water as solvent. Strong influence of temperature and humidity during application and drying, often fatal impact of apolar surface impurities which do not dissolve in water and cause craters or represent a weakening spot for adhesion to name a few. Consequently the first application areas were found in industries with highly controlled conditions, namely the automotive industry.
Nevertheless the high energy consumption of the air conditioning necessary is still perceived as a downside of water-borne technology in automotive and slows down the adaption of water-borne in less sophisticated markets. There are developments on the equipment sector which possibly will support the growth of water-borne technology, eg. electrostatic high rotation bell application which lends itself well to water-borne systems is used more and more also in industrial coatings. Recently an overspray-free application method has been developed, with the promise to reduce the demand for air circulation and hence energy consumption during application. These developments will help to grow water-borne even further into a broader range of industrial markets.
Florian Lunzer is Head of corporate innovation at Allnex.
The other big area for water-borne technology are architectural coatings, certainly for indoor applications but increasingly also for outdoor applications. The growth in this segment is coming from a continuous incremental improvement of the products pushing the boundaries to enable more and more challenging applications.
There are innovations on a product level that are targeting specific issues related to water-borne technology. Water-borne isocyanate-free 2 pack systems have been developed which eliminate the blistering encountered with the current isocyanate crosslinked water-borne products. Two-pack systems with increased reactivity to allow application at lower temperatures are another approach to broaden the application window of water-borne coatings to a certain degree.
What other trends technical trends do you see in water-borne coatings?
The general trend to reduce substances of concern is a challenge for water-borne systems as well. Certain toxic cosolvents like NMP, NEP are no longer tolerated in most applications, APEO surfactants and certain biocides are being substituted by substances of lower concern. The demand to reduce of VOC is also affecting water-borne technology as most widely used coalescents are considered VOC. A reduction in coalescents or a change to non VOC grades is consequently required in markets like architectural and even automotive. Especially in China there is increasing interest in water-borne clearcoats for automotive applications.
Another trend is the move to higher solids water-borne systems in order to minimize the energy demand and cost of transport. Furthermore the performance of water-borne acrylic dispersions is constantly improved and new resins with high corrosion resistance have been developed, allowing their application in “direct to metal” industrial applications as well as on certain parts of the infrastructure assets, typically replacing solvent borne alkyd systems.
The interview was conducted by Jan Gesthuizen
Remark: In an earlier version of this interview we used an article picture were the painter was not using proper security gear. We deleted that picture and replaced it with a new one. Of course safety is a key value for us and we apologize for the unfortunate choice of the initial picture.