Pigments Offer a New Family of Colorants Based on Diffractive Effects

Figure 1
The color effect produced by SpectraFlair pigment is generated by the diffraction of light waves due to the material's uniquely textured surface. Due to the high flake-diameter-to-thickness ratio, the pigment also has good leafing properties, thus creating a high level of specular reflection. SpectraFlair pigment is composed of only inorganic materials, thus providing very good durability and light fastness as demonstrated in accelerated weather testing.

Diffractive Flakes for Paint and Ink

SpectraFlairTM pigment diffractive effects are based on flakes with a microstructure resolution within the wavelengths of visible light. There are many demonstrations of diffractive optical effects in non-flake form, notably linear diffractive gratings on plastic or metal foils and holograms. Linear diffractive gratings are repetitive structures made of lines or grooves in a material to form a peak and valley structure (hundreds or thousands of lines per millimeter). Desirable optical effects within the visible spectrum occur when diffraction gratings have regularly spaced grooves at uniform depths on a reflective surface. Diffractive surfaces perform better with directional illumination in order to see the color effect.

Conventional structures and methods of producing flakes or particles with diffractive gratings have rendered such material unsuitable for obtaining the optical features achievable by foil structures. While these diffractive gratings are very successful as patterns and linear embossments in foils and plastics, most diffractive flake pigments have had one or more drawbacks of glittery appearance, low visual effect, or large flake size, resulting in a rough coating surface. Previous technology suffered from lack of flake orientation, poor durability, flake curvature, and most importantly lacked an aesthetically pleasing appearance. However, the SpectraFlair pigments represent the first high-performance, commercial diffractive technology in the form of a versatile pigment flake for paint and ink.

Figure 2
The microstructure of a SpectraFlair pigment flake is on the order of magnitude of the visible wavelengths of light. In viewing conditions with a unidirectional light source, the appearance of the rainbow spectrum is determined by the microstructure surface of the pigment flakes when in a coated surface. The pigment follows additive color theory and can be combined with other pigments and dyes to create custom color stylings.

"Liquid Metal"

The new SpectraFlair pigment has a silver base color with a diffractive rainbow effect that appears to emanate from the surface in pleasing and subtle tones. Seen in direct light, the pigment animates form and surface contour, enhancing product design and appeal. Some call it a "liquid metal" appearance that creates, in the viewer, a sense of "excitement" at the animated colors seen when the viewing angle or light source moves. These pigments can be combined with standard colorants to bring traditional flat colors to life.

Table 1

Flake Description

The pigment is a unique material consisting of an ultra-thin, diffractive pigment in the form of micron size flakes. The textured flakes have an average aspect ratio of 20:1. The pigment is opaque, thin, highly specular (mirror-like) and exhibits a rainbow-like diffraction effect. This multi-layer flake is comprised of magnesium fluoride and aluminum. In a coating application the thickness and relief of the pigment's flake structure produces a brilliant diffractive effect under direct light. The mean flake size is 21 micrometers, making its visual effect much smoother than other diffractive flake or particle technologies that create distinct glitter effects.

The pigment is produced under tolerances similar to semiconductor chip manufacturing technology. In manufacturing, to maintain the diffractive effect, the layer thickness and three-dimensional relief of the pigment must be controlled to precise tolerances. Flake layers on the microstructure are controlled to within 3-5 atoms thickness.

Application Characteristics

SpectraFlair pigment is readily dispersible in most vehicle systems. The pigment is easy to use and is often referred to as a "stir in" pigment and has been found to be compatible in a wide range of standard paint and ink formulations. It can be blended with aluminum, carbon black, and other inorganic and organic pigments to create a range of unique color effects.

These diffractive pigments are similar to other flake pigments like aluminum and mica. Paint containing this pigment may be repaired using the same techniques as those used for other flake pigments. Only 2-6% pigment, based on total formula weight, is needed to produce a dramatic color effect. Amounts may vary depending on the addition of other conventional pigments. Because of the high reflectivity of the pigment, it can be mixed with other pigments while maintaining desirable color effects.

This pigment is well suited to spray applications. Basecoat, clearcoat and midcoat systems have been formulated using solventborne paint. Manual or automatic spray guns may be used with or without electrostatic assistance. SpectraFlair pigment is non-arcing and is well suited to electrostatic application.

Solventborne basecoats can be prepared by blending resins, pigment dispersions, additives and the solvents necessary to adjust total solids and/or package viscosity. SpectraFlair pigment may be added as a dry powder or as a prepared pigment slurry. These pigments are being evaluated in a variety of tests simulating environmental exposure, circulation resistance and shelf stability.

Color Effects

SpectraFlair Silver 1400 pigment is basically a neutral color that may be used as the sole colorant or combined with other pigments and dyes to create subtle, sophisticated dimensions for products and spaces. The diffraction effect of the pigment depends on the interaction of light with the pigment surface. In diffuse light, similar to that of a cloudy day, the appearance of the pigment is comparable to a medium-grade aluminum. In lighting situations with a focused light source (a sunny, cloudless sky), the pigment exhibits a spectacular rainbow of colors. The entire color spectrum from red to orange, yellow, green, and blue will all be visible accentuating object contours.

Consumer Product Applications

These pigments create an extra dimension of color for applications in automotive and recreational equipment, footwear and apparel, personal electronics and packaging. In these applications, color designers can create unique surface-characteristic effects that are visually appealing and distinctive.

Summary

SpectraFlair pigment is a new light diffractive colorant manufactured by Flex Products Inc. that uses the company's light manipulating Color by Physics" technology. By controlling the physical dimensions and surface microstructure, SpectraFlair pigment Silver 1400 generates the appearance of multiple, bright rainbow producing prisms moving over a liquid silver color. The pigment has a pleasing, elegant and dramatic visual appeal that is unique, durable, and easy to incorporate. The pigment opens new worlds of design possibilities and adds value and appeal to virtually any product. Coatings containing SpectraFlair enhance the contours of 3-dimensional objects and create spectacular visual effects.

ChromaFlair(r) and Color by Physics(r) are registered trademarks of Flex Products Inc.

SpectraFlair', The Color Shift Leader' and Bringing Form to Life' are trademarks of Flex Products Inc.

For more information on pigments, contact Flex Products Inc., 1402 Mariner Way, Santa Rosa, CA 95407; phone 707/525.7007; fax 707/525.7537; e-mail SpectraFlair@flexprod.com; visit www.ColorShift.com; or Circle Number 120.