Which paint is best for road markings?

Thermoplastic road marking paint, also called hot melt marking paint, is a kind of powder paint. When applied as road surface markings, a hot melt kettle is used to heat it to 200 °C (392 °F) to melt the powder, after which it is sprayed on the road surface. After cooling, the paint forms a thick polymer layer, which is wear-resistant, bright, and reflective. In recent years, practical applications tests have proved that the marking lines lack surface roughness and can easily cause wheel slip, resulting in a traffic accident in snow and rainy weather. Therefore, some countries once restricted the use of this paint or demand the use of anti-skid particles. In order to increase the antiskid performance of the line, thermoplastic paint has added reflective glass beads and other coarse fillers. Thermoplastic can be used very effectively for large anti-skid areas on roads and pedestrian walkways by adding glass beads. It can be produced in any colour and is suitable for car parks, factory walkways, and many other areas. It hardens quickly and can be driven over after just a few minutes.

Components

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Thermoplastic marking paint consists of synthetic (polymeric or non-polymeric) resin, glass beads, pigments, fillers (fine like calcium carbonate and coarse like sand), packing materials, additives, etc.

1. Synthetic resin has thermoplasticity, make the hot melt coating fast-dry and strongly adhesive to the road surface. Non-polymeric resins, based on colophony, are also widely used.
2. Additives in the paint can increase the plasticity of the coating, and make it resistant to subsidence, pollution and color fading.
3. Pigments: the common colours of road lines are yellow and white. White pigment is titanium dioxide. Occasionally zinc oxide can be used, but it is less effective due to low refractive index. For yellow thermoplastics, organic pigments (like Pigment Yellow 65, 74 or 83) are mostly used; lead-containing pigments are obsolete and banned in essentially all developed countries.[

   citation needed

   ] Thermoplastic road markings can also be formulated in other colours.
4. Packing materials, as filling added into the paint, ensure mechanical strength, wear resistance, and color of paint coating. The particle size will affect liquidity and precipitation, as well as the surface processing.
5. Glass microspheres are added in order to improve the identification of lines at night, to improve the brightness and durability of the marking. Glass beads, usually 0.1-1.4 mm in diameter, are colourless and transparent; they reflect light from vehicle's headlights back toward the driver and foremost protect the road marking from abrasion.

Matched machines

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A road marking machine is a machine specially used to mark different traffic lines on road surface, and some can remark on old lines directly. It can screed, extrude, or spray processed road paint onto the road surface to form durable coating lines. A hot melt kettle is used for continuously heating, melting, and stirring thermoplastic marking paints, preparing molten paints for the thermoplastic machine, especially for long-distance road-line-marking work. The molten paint quality can affect the line quality greatly.

Microplastic pollution

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Thermoplastic paints, when used as road markings, are a source of microplastic pollution. Abrasive wear of road marking paint resins has been claimed to be responsible for 7% of all microplastic pollution, with estimates ranging from 0.7% to 19%.[1]

See also

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References

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Road marking—also known as line marking—refers to the application of paints and other high-visibility materials on roads, highways, runways, and other vehicle and pedestrian pathways to communicate important information. While the standardized system of colors, lines, and symbols employed can vary depending on the current federal and state guidelines, the underlying goal is always the same – ensuring the safety of the users (e.g., drivers, bikers, and walkers). 

There are many types of road marking paints available, each of which offers unique characteristics that make it suitable for different purposes. Below we discuss the various paint classifications and how to choose the right one for a road marking project. 

Types of Road Marking Paint

As indicated above, road marking paint comes in several variations, which differ in regard to formulation and performance. Some of the types available include:

• Water-based paints: Water-based paints serve as durable and reliable traffic paint solutions with smaller environmental footprints. They can contain a variety of materials, with the polymer binder usually being an acrylic latex. 
• Solvent-based paints: Solvent-based paints—also known as oil-based paint—contain greater quantities of organic compounds than water-based compounds.  This can allow for faster drying times that aren’t effected as much with temperature and humidity, like water-based coating are. They can be made from plant-based alkyd, synthetic acrylic, and other similar polymer materials.
• Two-component paints: As suggested by the name, two-component paints consist of two separate components (a polymer base and a curing agent). Combining them results in a chemical reaction that facilitates the drying of the paint. This chemical reaction is also not effected as much with temperature and humidity.
• Low VOC solvent-based paints: Low volatile organic compound (VOC) solvent-based paints utilize solvents, predominantly acetone.  The EPA has classified acetone to be exempt from detrimentally effecting the VOC of the coating.  This allows for the use of a solvent-based coating where a water-based coating was previously needed to meet low VOC requirements.
• Biorenewable paints: Biorenewable paints have formulations with significant quantities of biorenewable material, which makes them a more eco-friendly and sustainable road marking option. The first biorenewable road paint was Biostripe®, which continues to be a popular choice in VOC-restricted areas due to its longevity.

Key Selection Considerations for Road Marking Paint

When choosing a paint for road marking project, there are several factors to keep in mind, such as: 

• State and national regulations. As mentioned above, the regulations surrounding road marking can vary from country to country and state to state, with some state rules being more strict than federal rules. One of the factors affected by both state and federal requirements and restrictions is the VOC content of the paint; in the United States, national road marking standards call for formulations with less than or equal to 150 g/l of VOC, while some states (e.g., California) demand paints with even smaller quantities of VOC. Check out this map for additional information about state VOC limitations. 

• Location. Guidelines for road markings can also differ depending on where the markings will be placed (e.g., road vs. parking lot vs. airport runway). For example, high-traffic areas (e.g., parking lots) require paints that demonstrate high durability and longevity, while areas that require high visibility (e.g., airport runways) need paints with high reflectivity. 

• Environmental conditions. The conditions to which road markings will be subjected affect how long they will last. For example, water-based paints are generally unsuitable for environments with high moisture content, while paints with high-quality pigments are ideal for environments with high concentrations of UV light. 

Road Marking Paints From Aexcel

Aexcel is an industry-leading provider of high-performance coatings and paints. For road marking applications, our product offerings include: 

For more information about our road marking products or assistance choosing one for your needs, contact our team today.