"Wet transparency is the only reason titanium dioxide is needed above CPVC"

Modern fillers can do more than just increase the volume of coatings. We discussed the latest innovations and the potential for fillers to reduce their reliance on titanium dioxide with experts from Hempel and Omya.
at least for systems above critical pigment volume concentrations, titanium "wet transparency is the only reason titanium dioxide is needed," said Detlef Gysau of Omya, a large producer of fillers, . "Insufficient adhesive in the coating film leaves pores and fills the air after the drying process. Because of the large difference in refractive index between air and mineral fillers, the opacity above CPVC increases," Gysau explains.
Gysau is Omya's head of innovation and technology marketing. He is also the author of Paint Fillers.
the limits of
, but this policy has drawbacks that limit the applications that can use it. "If we introduce air voids in the film, we introduce some cover because the pigment air or polymer air interface is very different," says Satntiago Arias of hempel, a paint manufacturer. This increases the cover, but usually at the expense of other film properties. He added: "Depending on the type of coating you need, different types of fillers can partially replace titanium dioxide. To do this, you need to consider the main characteristics of the coating. "
Santiago Arias is Hempel's director of conservation research and development
In general, fine particles with particle sizes close to titanium dioxide do support opacity." When these ultra-fine mineral fillers are dispersed under the presence of titanium dioxide, they help to avoid optically inefficient titanium dioxide appendicides. In this way, up to 20% titanium dioxide can usually be replaced without losing its optical properties," explains Detlef Gysau.
trends in fillings in coatings
in addition to reducing dependence on titanium dioxide, Gysau expects an increased demand for more functional mineral fillers. "There are many reasons for this," he explains. Sustainability Trends - Costs and their volatility, availability and regulatory considerations, while regulation covers environment, safety, health and sustainability.
Santiago Arias, from Hempel, agrees and notes that "new fillers should meet global environmental trends aimed at reducing volatile organic compounds, which require higher solid content and no solvent or water-based coatings." This
based on a series of expert interviews in the European Journal of Coatings 1/2019. Subscribers to The European Coatings 360 degrees get a full interview.