Traffic paint is a thin layer of blended material. Paint is mainly composed of finely ground pigments that are mixed into a resin or binder system. Then various ingredients and additives are incorporated for certain desired properties. A liquid (water or solvent) is added to the mixture to produce a material that is pliable by application equipment. All of the ingredients/components in traffic paint are added specifically for one or more of the following functions: aiding the manufacturing process, increasing storage time in containers, easing application, and increasing durability once the paint has been applied.
Components of traffic paint
– Prime Pigments: Prime pigments are used to impart chemical properties such as UV stability, or physical properties such as color and hiding. Hiding is the ability of a paint to cover or block out the surface (substrate) beneath it. Titanium dioxide is typically used to make a white color. It is the primary pigment that gives traffic paint good hiding power.
– Extender Pigments: Once the necessary amount of prime pigment is added for hiding, less expensive extender pigments or fillers are used to bring the pigment level up to the required point. Extender pigments not only reduce cost, they give paint consistency, durability, permeability, and scrubability. These properties are very important when considering the harsh environment and abuses that traffic paint must withstand. The main types of extenders are aluminum silicate (china clay), calcium carbonate, calcium sulfate, and magnesium silicate.
– Resins or Binders: The resin is the component that bonds the pigment and beads together. It also provides the adhesion to the road surface. The resin is the binder or glue in paint. Waterborne paints typically use three types of resins. They are polyvinyl acetate latex, methylmethacrylate, or a one-hundred-percent acrylic resin. These materials are pre-reacted and put into solution using emulsifiers. These emulsions are materials that normally do not mix. Once the paint has been applied, it must allow the water to evaporate in order for the paint to “break” and adhere to the roadway. This settling is generally called coalescence. One-hundred-percent acrylics are used predominantly due to faster “no track” times and less heat needed during application.
– Solvents: With waterborne paint, the water is more of a diluent rather than a solvent. It holds the resin emulsion in solution with the other components until the paint has been applied. Fast-dry waterborne paints may contain ammonia and/or methanol. Ammonia and methanol are Volatile Organic Compounds (VOCs). These VOCs accelerate the curing process throughout evaporation. In solvent borne paints, the evaporation rate is very important. Because of this, they need to be tailored to leave the film at the right time. When solvents evaporate too fast, the surface can skim over and trap the rest of the solvents within the film. Most solvent blends keep the film open while solvents escape. That is why, as a general rule, just any solvent will not work.
– Additives: Additives are included in paint to help prevent problems. One example is an anti-foam agent, which keeps paint from foaming during the high-speed mixing process. Other additives help prevent the paint from freezing, settling, or skimming in the drum. Additives usually only make up 0.1 to 5 percent of the paint. Some have a single function and others may have multiple functions. For example, ammonia acts as an accelerator for drying and keeps the pH level up in waterborne paint while being stored. It is important to maintain the pH level at 9.5 or higher to ensure the latex remains suspended in solution.