LUXAN effect pigments belong to the group of pearlescent effect pigments that are composed of low refractive transparent substrates coated with high refractive metal oxides, e.g., titanium dioxide or iron oxide. This layered structure enables interference effects, creating the typical pearl luster as frequently found in nature. For decades, natural mica was the state-of-the-art substrate for those pearlescent pigments, but mica shows some basic deficiencies, such as naturally occurring deviations of the chemical composition, irregularly shaped platelets with many edges, and thickness deviations within single mica particles. These deviations lead to undesirable scattering phenomena and inhomogeneous interference colours.

Figure 1 Click to enlarge

In contrast, LUXAN pigments are based on artificial borosilicate platelets with a well-defined chemical composition and a uniform individual particle thickness. This homogeneous thickness of the individual glassflakes and also the total thickness (approximately 1 µm), which minimizes the influence of the carrier on the final interference colour of the metal oxide-coated effect pigment, leads to very uniform and pure interference colours.

In addition, the glassflakes exhibit excellent surface smoothness and high transparency. The metal oxide coating of those superior substrates results in effect pigments with unique colour purity and extraordinary gloss (Figure 1).

Patented Technology

Effect Pigments Comprising a Glassflake Substrate

Figure 2 Click to enlarge

The use of a specially developed glass that exhibits extraordinary adhesion tendency to metal oxides results in a very smooth and homogeneous metal oxide coating of the glassflakes. This effect can also be proven by SEM analysis, which clearly shows the difference between ECKART’s coating technology based on the new glass composition versus state-of-the-art products (Figure 2).

Figure 3 Click to enlarge

The macroscopic result of this phenomenon is less diffuse scattering of light and optimized gloss of ECKART’s glassflake-based pearlescent pigments, proven by gloss readings taken from nitrocellulose drawdowns with a BYK micro-trigloss. Both LUXAN products E001 and E241 achieve significantly higher gloss values compared to corresponding customary grades (Figure 3).

The metal oxide coating of ECKART’s special glass composition is based on patented technology (EP 1980594). The new glass composition is different compared to all typical standard glasses (e.g. C-glass, A-glass or E-glass) in terms of metal oxide content and chemical properties.

Effect Pigments Based on Artificial Substrates with a Narrow Particle Size Distribution (EP 2093260)

Figure 4 Click to enlarge

The excellent particle size distribution of the LUXAN pigments provides a high colour purity of metal oxide-coated interference products. The effectiveness of the particle size distribution can be quantified by the span, which is defined as: DD=(D90-D10)/D50. A small span corresponds to a narrow particle size distribution. The LUXAN products exhibit a span of approximately 1.0.

Figure 4 (micrographs) compares a customary grade with the LUXAN E241 pigment. The picture on the left-hand side shows the LUXAN pigment with a uniform particle size and shape. In contrast, the customary grade (right-hand side) also contains very coarse and fine particles with different interference colours. In this case the small particles have a violet-reddish colour and the coarse particles have an orange colour. This effect macroscopically results in a higher colour purity of the LUXAN product.

New Borosilicate Pigments

Table 1 Click to enlarge

LUXAN pigments were originally introduced at the ECS in 2009 and are today available within the product portfolio listed in Table 1.

LUXAN effect pigments distinguish themselves from traditional natural mica-based pigments by their extraordinary luster, sparkle effects and glamorous look. The smooth metal oxide coating of the calcium sodium borosilicate leads to very high transparency and pure interference colours.

The product line is available in four different particle sizes (Table 1). The finer C-fraction exhibits a subtle and gentle, but still impressive, sparkle, whereas the extra coarse F-fraction combines highest transparency with extreme sparks. The E-fraction includes pigments with outstanding pure and intense interference colours and extraordinary luster.

The latest innovation, LUXAN D393, combines extreme gloss and sparkle effects with a high chroma and very pure golden interference and absorption colour.

The effect combination of high transparency and also high chroma colour intensity enables new possibilities for design and styling. Especially in coating applications LUXAN products show nearly no impact on the base colour of the coating at flat observation angles due to their high transparency. The sparkle and luster effect suddenly appear when changing to the specular viewing angle. LUXAN effect pigments can be used in all kinds of applications of conventional effect pigments, e.g., automotive and industrial coatings, powder coatings, textile and leather coatings, printing inks, plastics and the like.

SHINEDECOR Effect Pigment Concentrates

New effect pigment concentrates under the brandname SHINEDECOR, which combine advanced processing options, high compatibility, low influence on the paint properties and improved product quality, have been recently developed.

SHINEDECOR pigment concentrates are entirely free of binders and solvents. Besides water, SHINEDECOR only contains small quantities of appropriate wetting and dispersing additives as well as defoamers and rheology additives of the water pollution classes 0 and 1. All criteria for the development of ecologically friendly materials (equivalent to the environmental sign RAL ZU 102) are fulfilled. The most distinguishing features are: VOC free; APEO free; and plasticizer free.

The almost universal compatibility with the majority of water-based coating systems provides flexible handling. In addition, the easy incorporation of the effect pigment concentrate should be mentioned here, even “stir-in” by hand is possible.

With SHINEDECOR, brilliant effects can be obtained in ecologically correct wall paints, in aqueous leather colouring agents, in water-based varnishes for woodwork as well as in aqueous industrial coatings, and in all other kinds of decorative glazing. SHINEDECOR concentrates are already available for aluminium, bronze powder and pearlescent pigments. Two corresponding Shinedecor LUXAN products were introduced into the market in early 2010 (Shinedecor E001 and Shinedecor D393), and further grades will follow in 2011.

For more information, visit www.eckart.net.