Without dispersants, the world would be a much less colorful place. Dispersant additives can be found everywhere pigment is found, meaning they’re in a tremendous range of products…that metallic dark blue SUV you saw on the highway. The gray grained ceramic plank flooring tiles at your favorite restaurant. The ultra HD 4K flat panel TV calling your name at Best Buy. A colorful bag of chips on your grocer’s shelves. Think of a product and chances are, dispersants are involved.
Without dispersants, solid particles in the coating, ink or paint are attracted to each other, which is called an agglomerate (a larger particle composed of smaller ones). This can adversely affect the desired properties, like appearance (opacity, gloss, color); performance (corrosion resistance, reinforcement); compatibility; stability, etc.
The process of dispersion, also called milling, is done to get as close as possible to the primary particle’s original size, which improves the application process and provides better end performance. The process requires the use of an additive (a dispersant) to keep the smaller particles from recombining, which is what they would naturally do. The process of dispersion is an early step in turning a pigment/particle into something that adds value.
Matching the Dispersion to the Application
Dispersants offer a number of unique, customizable benefits for many different types of applications. Following are just a few of those specific applications.
In the automotive industry, dispersants in the surface coating help make metallic blue on an SUV—or any color on any type of vehicle—really pop. That pop comes from the use of transparent organic pigments in combination with metallic effect pigments. The organic pigments need to be dispersed in a very fine way, known as nanodispersion. The process requires a dispersant designed specifically for this task that is matched to the pigment and the coating to deliver incredible depth of color. Underneath the surface coating is the primer coating, where anti-corrosive dispersants provide protection.
Digitally printed ceramic tile that looks like wood grain is a fairly recent development. To achieve decorative effects like this on tile previously involved a 4-color screen printing process that needed a different screen for each color. Getting a stone or random effect was challenging. With newer technology, these types of tiles can be created using ink jet printing, regardless of the substrate. Ink jet printing allows for an infinite number of patterns to randomize the pattern generation. Ceramic pigments are very dense with a high specific gravity, which means they tend to settle—factors that don’t lend themselves to the ink jet printing process. Properly designed dispersants flip the script, allowing you to manufacture a range of ceramic colors quite effectively. Lubrizol pioneered this dispersant technology, enabling the conversion of mass-produced ceramic tile from design-limiting screen printing processes to an infinite range of opportunities by using digital printing.
Flat Panel Displays
Dispersants are also critical to colors in liquid crystal displays (LCD), which consist of a red, green and blue filter. The filters are printed over liquid crystals and switching circuitry, which are turned on or off to display the correct color pixel. The color filters are produced using a very specific type of transparent organic pigment. The nanodispersion and stabilization used with LCDs are similar to those used in auto coatings, but the pigments, coatings, inks and the process are quite different. Custom designed dispersion technology allows a highly defined reproducibility in the display technology. Dispersions are also key to the tiny black masks that surround each color filter. The masks are created with carbon black, which needs exceptional stability and control over the dispersion, flow and coating properties of the inks to achieve desired performance. Flat panel displays are another example of designing a dispersant to work in a very specific, high-tech application.
Dispersants are used in all kinds of packaging, such as food packaging of all shapes and sizes that gets its vital shelf appeal and brand recognition from vibrant inks and protective overprint coatings. Dispersant manufacturers, like Lubrizol, can work with the ink manufacturer to achieve the same color space regardless of whether
it the ink or coating is solvent based, water based or UV-cured and whether printed by inkjet, flexo or litho printing process. Packaging manufacturers can achieve the same Pantone specs for the targeted ink regardless of ink type, chemistry or printing process, with dispersant technology enabling effective processing and high strength as films continue to become thinner.