A Novel Micronized High-Performance Rutile Yellow: New Options – New Chances

Formulating a high-performance coating system has become an everyday challenge. Not only do the technical requirements need to be met, but more and more, economic aspects need to be considered as well. To meet these challenges, innovative new ideas and concepts in formulating high-performance coatings are required.

By optimizing the well-known chrome and nickel titanium yellow chemistries, which exhibit outstanding fastness and durability, a new class of pigments has been obtained offering a versatile tool for formulating economic and innovative coatings.

Customers who use these new formulations are achieving a 25-30% savings and at the same time receiving improved performance!

The improvement is accomplished by an innovative and proprietary technology to micronize the pigments while keeping their excellent weather and light-fastness as well as their exceptional temperature resistance.

The Pigments

Typically, chrome and nickel titanium yellows show an average particle size of >1µm. After micronizing, a smooth and controlled downsizing of pigment particles the average particle size is about 0.3 µm (Figure 1).

This micronization technique produces a narrow particle size distribution of spherical-shaped pigment particles (Figure 2), which enhances hiding power and opacity as well as significantly reduces abrasiveness.

A detailed overview on several pigments optimized by this new micronization technique and some of their properties is given in Table 1.

Performance

In modern coatings systems, the high performance of these types of inorganic pigments is a key asset. This is especially seen when they are used in combination with organic pigments where the hiding power and opacity of the inorganic pigments are crucial. In this case, the micronized grades with their unique hiding power will outperform a high-performance titanium dioxide grade (Figure 3).

This exclusive property of the rutile yellow pigments allows substituting titanium dioxide in formulations by achieving higher cost efficiency. Tables 2 and 3 show two examples of customary industrial coatings color shades.

In addition to the possible cost savings of about 25%, the new formulations based on the micronized rutile yellow pigments provide further valuable benefits. By deploying the new micronized grades in combination with high-performance organic pigments the weather fastness of the organic pigments will be significantly improved.

This improvement is based upon the drastically reduced photocatalytic effect and the absorption of the critical electromagnetic short wave radiation; even when compared to super-durable titanium dioxide grades the degradation of the organic pigments will be diminished radically. Hence it is possible to realize higher flexibility in selecting the organic pigment components.

The controlled and optimized particle size distribution of the micronized rutile yellow pigments in combination with their spherical shape allows higher gloss values for brilliant and glossy coatings (Figure 5).

These optimized pigments also show reduced abrasiveness. The formulator will see this in a reduction of process costs as well as in easier processability and handling of the micronized rutile yellows.

In the segment of high-value industrial coatings, the formulators’ focus is not only on the coloristic properties of pigments or their light- and weather-fastness, but also on their ease of stabilization in the coatings system. The challenge is to control the economic efficiency positively while maintaining a maximum of application-oriented flexibility and compatibility of the formulation.

During the development of pigment preparations or multi-functional intermediates it is essential to base the formulations on the excellent ability of pigments relative to their stabilization by additives. Therefore the efficient and economic use of valuable dispersing and stabilizing additives is the key to successful formulations. In this regard, the micronized rutile yellow pigments show outstanding performance. Figure 7 displays the dispersant demand of common commercially available additives of HDG150¹ in relation to a super-durable titanium dioxide pigment.

The comparison reveals a striking advantage of the new micronized pigments especially in formulations as shown in Tables 2 and 3. The potential dispersant savings is 40-60% compared to the use of titanium dioxide.

The selected replacement of titanium dioxide with the micronized rutile yellow pigments leads to a higher economic efficiency along with a reduced use of additives. This allows for higher compatibility with a multitude of different coating systems.

New Options - New Chances

These novel, micronized, rutile yellow pigments are proving to be true high performers in modern coating formulations. Besides their well-known exceptional properties like weather- and light-fastness or temperature resistance, they offer the formulator integral features that are most essential in formulating high-performing, cost-conscious coatings.

The features include outstanding hiding power and opacity, reduced abrasiveness and the significantly beneficial dispersant demand compared to other pigments like titanium dioxide. This allows for a higher degree of flexibility and a higher technological compatibility. Therefore, these new pigments are an excellent alternative to the widely used titanium dioxide pigments.

Modern rutile yellow pigments combine synergistic as well as economic advantages to give the formulator the tool they need to develop high-performance, economically feasible formulations.

This article was also published in Farbe & Lack, May 2007.