Waterborne coatings conversion

Whilst there are some thermoset acrylic emulsions cormnerdally available, the bulk of the thermoset resins, used as the main binder system, are produced in solution. Some may then be made waterborne by neutralisation and inversion (dispersion) into a water phase. Lower molecular weights favour this qrproach. The rate of conversion from solvent based to waterborne industrial thermoset coating systems has been, and is, much slower than the conversion from architectural alkyd paints to emulsion altonatives. There are two principle reasons for this. Firstly there are problems of application and substrate wetting of many waterborne systems. Secondly, the modifications frequently required to induce water dispersibility reduce one or more of the essential performance properties required from the cured film, compared to a solvent based system. Water resistance, with many films having an increased tendency for blushing is one example. However, for some applications, such as electrodeposition, only waterborne systems will work. 

Although not discussed in this chapter, changes in solvent composition will shift to be more ecologically friendly. Conversion to fully compliant hazardous air pollutant solvents (HAPS) will require complete reformulation of most coating resins. Free solvent replacement to HAPS compliant can occur immediately and substitution in all manufactured resins should be fully implemented within the next few years. Greater use of waterborne materials (primers, basecoats, and clears) is expected within the next five to ten years as long as application properties, performance, and durability can be attained. 

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