Pigment Dispersion for Automotive Coatings

Pigment Dispersants Yield Colorful, High-Performance Results

Posted by Performance Coatings Team on 12/04/2018

Red means stop. Green means go. Orange is equated with hazard. Blue often means water or cold.

Color is all around us every day, helping us interpret the world, change actions and cause reactions (both positive and negative). In the coatings industry, what delivers these bursts of color? That’s an easy one. Pigments—the tiny solid particles used for coloring paint, ink, plastic, fabric and more.

But what keeps pigment particles apart, preventing their tendency towards reagglomeration, to maintain the desired color quality? And maintain stability in both the millbase or final coating in both the wet and dry state?

Pigment dispersants.

A well designed pigment dispersant is critical. In addition to achieving excellent tinctorial properties, such as gloss, haze and color strength, there should be no negative impact on the final coating properties, like water uptake or corrosion resistance. Polymeric pigment dispersants are designed to have a segmented structure with a pigment-affinic anchoring segment and a solvent-soluble stabilization chain. 

With increasing regulatory and environmental requirements, there is a drive toward developing water-based VOC free pigmented coating formulations with the same aesthetic properties as solvent-based systems. In water-borne industrial coatings, well-designed pigment dispersants can deliver superior performance.

A well-designed pigment dispersant will have a well-defined polymer structure with good control of molecular weight and an optimum balance of stabilizing segments to anchor segments. When this is achieved, the actual amount of dispersant required can be less than the theoretical requirement. This provides an advantage as less hydrophilic material is introduced to the coating formulation, which may eventually impact coating durability through ingress of adverse agents: O2, H2O, salts from the surface environment.

Single anchor (SA) dispersants work very effectively on specific pigments, whereas multi anchor (MA) dispersants have better compatibility with various pigment types and can help disperse carbon black, organic and inorganic pigments.

Lubrizol has developed novel anchor groups that have enabled the design of improved dispersants that can be formulated into coatings with superior jetness and color control. Testing has revealed that these dispersants can reduce the particle size in a much shorter time than conventional dispersants, using less energy during the milling process, while providing the required stability and compatibility in the coating formulation.

Through efficiency in design together with judicious selection of stabilizing chains, the dispersant can also be optimized to minimize its impact on water sensitivity and corrosion resistance and maximize resistance to physical, mechanical and chemical attack 

By applying these design principles, Lubrizol has added to its comprehensive line of Solsperse™ Hyperdispersant technologies, including the two newest dispersants for water-borne coatings. Solsperse™ W100 is a highly efficient dispersant targeted at a wide range of pigments and resins with minimal film impact. Solsperse™ W200 provides extremely fast dispersing of carbon black and other organic pigments.

Optimizing the dispersion of pigments is key to product performance. Learn more about Solsperse Hyperdispersants or contact your local Lubrizol account manager to get the most out of your colors. 

Performance Coatings Team

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