The integration of pigments in coatings for autonomous vehicles presents a unique set of challenges that are critical to the functionality and safety of these advanced machines. As autonomous vehicles rely heavily on sensors and cameras to navigate and interact with their environment, the pigments used must be carefully selected to avoid interference with signal transmission. Moreover, they must possess the durability to withstand various weather conditions while maintaining their reflective properties. The complexity is further compounded by the need for these coatings to be aesthetically pleasing, as well as compliant with stringent industry regulations regarding environmental impact and safety standards.

LUXAN CFX B604 Midnight Silver is a new kind of effect pigment based on borosilicate glass that was developed specifically for distinctive silver-grey formulations where a high sparkle is required. It is part of the company’s patented radar transparency solution for silver metallic full tones, and is highly compatible with other pigments, particularly aluminum effect pigments and the SYMIC OEM Opaque Silver product range for autonomous driving. This range of special pigments with a metallic look has a high radar transparency, which is essential for applications where conventional metallic effect pigments reach their limits.

The new technology consists of titanium dioxide and a specially developed mixed-oxide component of titanium and iron oxide, which gives the effect pigment metallic characteristics like a dark-down flop and opacity. In comparison to an interference silver, the addition of a specific titanium/iron-oxide modification contained in the coating lends the pigment a high-sparkling, silver-grey metallic appearance.

Flop Index/Opacity (Color Density) 

LUXAN CFX B604 Midnight Silver offers a captivating silver-grey effect with a high sparkle and a 3D appearance, providing various stylistic possibilities. It is particularly suitable for silver-metallic applications that demand intense sparkling effects. Its mineral composition grants a high level of radar transparency, similar to opaque-silver types, while retaining metallic optical characteristics such as the typical metallic flop and high opacity (Figure 1). 

Radar Transparency Solution for Silver Metallic Full Tones

The company’s solution for metallic effects with only slight radar damping is to combine aluminum effect pigments with opaque types and/or midnight silver. These options function as a radar transparency spacer with metallic optical characteristics between the radar-impermeable aluminum pigments (Figure 2).

There are many different factors influencing radar performance, such as film thickness, orientation, substrate, number of particles, binder/pigment ratio, and more that possibly influence the results. All of these factors have to be taken into consideration when formulating an optimized coating for autonomous driving.

Aluminum effect pigment types with finer particle sizes are more suitable for keeping the high coverage and the aluminum content as low as possible. In addition, encapsulated aluminum effect pigments show advantages for radar-transparent formulations. The proportion of opaque silver with aluminum effect pigments in the formulation significantly influences radar transparency. A higher proportion of opaque silver types means lower radar attenuation. A good starting point is to use a 50:50 ratio of opaque pearl types to aluminum pigments (Figure 3).

By combining LUXAN CFX B604 Midnight Silver with OEM Opaque Silver types, coatings manufacturers gain access to an exceptional toolbox for formulating radar-transparent metallic effects or achieving outstanding silver-grey stylings. The midnight silver effect pigment also offers excellent weather, chemical, and shear stability, and can be easily incorporated into water-, solvent-, and UV-based systems.

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*All images courtesy of ECKART GmbH.