When it comes to cars, black—and jet black in particular—has always been one of the most popular colors of all time. Henry Ford once famously said, “Any customer can have a car painted any color so long as it’s black.”
Ford took that stance for the sake of efficiency and uniformity. Either way, black has been one of the most prevalent colors since the early days of the automotive industry. The demand for black finishes remains strong today, with black and white competing for the most popular car color each year. That means the demand for automotive refinishing paints in these colors is also high.
The challenge in manufacturing black refinishing paints comes in managing the multiple variables that go into achieving the desired jetness, which refers to how black the finish is. Many consumers value dark, jet black vehicle finishes with bluish undertones, which means the “jetter” the better. For manufacturers of automotive refinish coatings, their products must closely match the jetness of OEM paint when used to repair vehicles.
Carbon black pigments are used to achieve jetness and bluish undertone in both OEM paint and automotive refinishing paint. The pigments must be stable in coating systems and must be highly resistant to weathering. Dispersants are used to help deliver pigment stabilization and high jetness levels, combined with a strong bluish undertone.
Typical carbon black pigment grades for automotive coatings have a much higher surface area and smaller pigment size than carbon black grades used for non-automotive applications, which makes it harder to disperse and stabilize. While in many coating applications, a common goal is to disperse particles as small as possible in the formulation, this is not the case for achieving automotive jetness. The objective here is to not fully disperse, but just enough to be stable and get a good dispersion.
Where jetness is desired, the goal is for a slightly higher particle size so that it will reflect a bluer shade on the color. With the “jet” carbon blacks, high molecular weight polymer dispersants are needed to achieve the best color, making the dispersion and stabilization of carbon black much harder to achieve. A dispersion of a carbon black with much smaller particle sizes could generate an undertone on the yellow or brown side, and not the desired blue tone. The blue undertone gives the perception of darkness and depth (jetness). That depth is lost with yellow undertones, even if the black color is strong and there is high tinting strength.
There are many manufacturers of automotive refinish coatings, ranging from multi-nationals to smaller manufacturers. The smaller manufacturers often lack the same resources as the bigger companies. They need to provide a finished product that is as close as possible to the original paint, but with cost pressure to formulate it at a lower price than the major manufacturers. The challenge comes in fulfilling the objectives of performance and cost.
A Jetter Black Finish
Lubrizol can help manufacturers overcome the challenge of achieving desired jetness in vehicle refinish paints. We work with customers to optimize their formulations because carbon black pigments for automotive paints are challenging to disperse and stabilize.We do this by enabling production of carbon black dispersions that deliver good stability and dispersion while providing the required blue undertone.
We consider variables (raw materials, pigments, dispersants, milling process), formulation and process to match that jetness and keep the bluer undertone under control. Formulation is very important because there are many refinish paint producers, each with their own formulation, but all with one end objective—a jetter black finish.
We also work with customers who share formulations for testing and to help optimize those formulations. There is no single answer to meet all the demands of the industry. Everything must be evaluated and customized based on the manufacturer’s needs and use of base variables. The purpose of our work is to achieve the best performance with an acceptable formula cost for manufacturers.
Solsperse™ Hyperdispersant technology set the benchmark for the automotive OEM paint manufacturers. We’re bringing that same technology together with our experience and gained knowledge to help paint refinish manufacturers achieve jetness.
Contact a Lubrizol expert to learn more about our dispersants for automotive refinish paints.