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Nordkalk’s paint innovation enables titanium dioxide to be replaced with limestone-based products

The new paint is environmentally friendly and its raw material costs are lower. Interest in the product has also intensified due to the impending change, taking place in the beginning of October, to the chemical classification of titanium dioxide as a potentially carcinogenic substance.

“We’ve managed to replace some of the titanium dioxide previously, but the new blend we’re now working with enables it to be done away with completely,” explained Juuso Hakala, Nordkalk’s key account manager specialising in the chemical industry segment. “Replacing it makes sense both financially and from an environmental point of view, because the complex production process of titanium dioxide produces a carbon footprint that’s more than five times the size of the one generated in the production of the limestone-based products replacing it.”

Laboratory Analyst Victor Väänänen and Application Manager R&D Matti Lammela have been working on replacing the titanium dioxide for years.

Matti Lammela from Nordkalk’s Research and Product Development Department says that replacing titanium dioxide has been the aim of the department’s work for a number of years. Pressure has increased due to the European Union’s decision to classify the substance as carcinogenic (i.e. causing cancer) upon its inhalation. This means that a warning about the cancer risk when spray painting must be included on the packaging of any paint whose titanium dioxide content is more than 1%.

“There’s good reason to assume that the new classification will pique paint manufacturers’ interest in replacing titanium dioxide,” Lammela said. “We’re already able to do that, at least in part, using products from our Nordkalk Enrich series that contain ultrafine precipitated calcium carbonate or PCC, and in future by using our completely new blend, which we’re working on with our clients at the moment to fine-tune.”

Solution found after 138 tests
Despite its environmental impact, titanium dioxide is found in almost all paints because it is considered an incomparable pigment due to its extraordinarily high refractive index, i.e. its ability to reflect light. This enhances the paint’s coverage.

“Coverage is one of the critical qualities of paint,” Lammela explained. “We tried boosting it using other pigments at first, but they didn’t work. Last year we tried increasing it by adding a filler, mostly made up of a product from our Nordkalk Enrich series and partly of ultrafine limestone powder. By playing with the amounts of the two and doing lots of tests, we managed to bring coverage up to the commercial paint level in just a few months.”’

Adding a filler leads to problems with the other critical qualities of a paint, such as its viscosity. “The wrong level of viscosity, which is to say whether a paint is too thick or too thin, will negatively affect how well it can be applied,” Lammela added. “Lots of paints with fillers also tend to crack easily, particularly in cold climates. We solved that problem by adding a mineral called wollastonite to the blend, whose needle-like structure stops cracks from forming. A complete, dense covering also makes paint more resistant to wet friction.”

Lammela says that development work is all about patiently seeking out a happy medium, striving for balance between qualities. “Usually the way these things work is that when you get one quality just right, another is thrown off,” he explained. “That’s why you have to do so much testing. As part of this project we’ve done 138 tests so far.”

These tests have reassured the Nordkalk team that titanium dioxide-free paints which meet the commercial quality requirements of clients can be developed.

“We’re launching lots of new development projects with our clients, and we’re hoping that the end products based on this innovation will be available for use within the next couple of years,” said Juuso Hakala.

For further information please contact:
Juuso Hakala, Key Account Manager | juuso.hakala​@nordkalk.com | +358 20 753 7339
Matti Lammela, Application Manager | matti.lammela​@nordkalk.com | +358 20 753 7260

Nordkalk is the leading company providing limestone-based products and solutions in Northern Europe, with a significant presence in Central Europe. We deliver essential raw material to numerous industries and focus on sustainable solutions that help our customers reduce their environmental impact. Our solutions contribute to clean air and water as well as the productivity of agricultural land. With operations in more than 30 locations in Europe, we are always near our customers. The company employs around 820 people, and in 2020 it had a turnover of EUR 276 million.

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