Every day, color formulators are challenged to select affordable pigments for coatings required for durable applications. Their choices are restricted due to environmental and performance concerns. Rockwood Pigments offers a novel chemistry that provides unique solutions in the yellow and orange color space.

A New Pigment Chemistry

The Solaplex™ range is a new class of inorganic pigment, CI Pigment Yellow 216. This soft, spherical complex consists of a tin-zinc-titania compound. This range is free of encapsulation and surface treatment and, thus, is compatible with a wide range of polymers and vehicles. The pigment is shown in the scanning electron micrograph (SEM) (Figure 1).

Unique Color Space

The Solaplex range occupies a unique color space, as shown in Figure 2, that consists of yellow, mid yellow and orange. These pigments exhibit opaque, clean, high-chroma shades in mass tone and clean in reduced shades. The color and shade intensity lies between lead chromates and conventional nickel and chrome titanates.

Solaplex inorganic pigments are ideal alone or in combination with high-performance organic pigments and titanium dioxide to produce a full color palette.

This range is an excellent alternative to lead-based formulations due to its low metamerism. The Solaplex range reflectance curve follows closely that of lead chromate. Color data is exhibited in Table 1.

Product Performance

In addition to the unique color space, the inorganic chemistry of Solaplex pigments gives exceptional performance, excellent opacity and hiding power. Chemical resistance, excellent weather fastness and light fastness are also key benefits for high performance and exterior coatings.

Acid Resistance

Color formulators need to select pigments that are chemically inert for demanding applications. This is a major issue for coil coating applications, which require pigments that are resistant to acid rain and sulfur dioxide. In a Kesternich sulfur dioxide exposure test, the Solaplex range was compared to a series of weather-fast, conventional inorganic pigments. Solaplex pigments were found to have equivalent resistance to nickel and chrome titanate and superior resistance to bismuth vanadate, as reflected in exposure panels in Figure 3.

Exterior Weathering

Exterior coatings for the agricultural, construction, engineering, marine and automotive markets require excellent fastness to light, weather and gloss, in full shades (masstone) and reduced shades (tint). Panels with Solaplex pigments were exposed to two years outdoors in Florida in full shade and reduced shade and accelerated weathering (Figures 4 and 5). Results indicate that the Solaplex range is equivalent to titanates after two years exterior Florida weathering in full and reduced shade. Solaplex pigments also exhibited superior gloss retention.

Performance

High performance is of paramount importance to color formulators in the coatings industry. Pigments sometimes must endure harsh environments during processing and in use and, thus, need to be robust to resist change.

The soft, spherical pigment particles of the Solaplex range are less abrasive and are easy to disperse. The low oil absorption allows for high pigment loading without adverse effects on rheology and gloss. Formulations using Solaplex pigments have been found to reduce orange peel effect, particularly in powder coatings.

Controlled particle size distribution of the Solaplex range results in pigments with clean undertone and excellent hiding power. High hiding power and opacity make them suitable for use with transparent high-performance organic pigments. Physical and chemical properties of the pigments are detailed in Table 2.

Applications

The overall durability and temperature stability make Solaplex pigments useful for a wide range of application in coatings and plastics. The chemical resistance of Solaplex pigments makes them suitable for use in acid-catalyzed and acidic environments.

Applications such as exterior and masonry paints, architectural and coil coating are particularly important; here Solaplex pigments provide a unique range of coloring options in the yellow and orange color area with excellent durability.

In the automotive coatings market, the novel color area, opacity and superior weathering are seen as a real benefit compared to organic pigments.

In addition, the combination of Solaplex™ pigments with high performance organic pigments give the most cost-effective alternative to lead chromate-based colors in applications such as powder coatings.

New Options

Solaplex technology is a new chemistry that provides unique color options to the formulator. It offers an environmentally acceptable alternative to pigments containing lead, chromium and molybdenum. In addition, Solaplex pigments are heat stable, light fast and resistant to acid, alkalis and weathering.

Their wide compatibility in full shade and reduced shade make Solaplex pigments a perfect partner with which to formulate cost-effective colors, either as single pigments, or in combination with inorganic or high-performance organic pigments. The ease of dispersion, bright, clean shades and excellent hiding power place these novel pigments in a class of their own in the coatings market.

For more information, visit www.rpigments.com. For a Solaplex brochure, technical data sheet and/or product sample, contact Larry Lane at 800/638.4444, ext. 423, or email info.us@rpigments.com.