Traffic marking paints are applied to newly constructed, repaved, and existing roadways, parking lots, and airport runways. In 2016, the volume of the global traffic marking paint/coatings market, including paints, thermoplastics, preformedpolymer tapes, and others, was estimated by Grand View Research to be nearly 1,370 kilotons. Polaris Market Research pegged the value of the global traffic road marking coating market at $4.0 billion in 2017 and anticipates that it will expand at a compound annual growth rate of 6.2% through 2026. Paints are used for travel lanes, loading zones, and parking spaces, while thermoplastic (hot-melt) coatings are increasingly used in locations that experience harsh weather conditions and for applications that involve heavy wear. Preformed polymer tapes are cold-applied plastic sheets used for marking traffic lanes, crosswalks, and stop bars. Increasing investment in infrastructure in emerging markets and a growing focus on maintenance and repair in mature economies are driving demand growth on a global basis. New developments are being driven, in part, by interest and investment in intelligent street marking systems that can communicate with vehicle and other sensors.
Focus on Liquid Traffic Marking Paints
Most liquid traffic marking paints today are waterborne systems, although solvent-based formulations are still specified for some applications. “As federal specifications and environmental requirements tighten, waterborne traffic paint is preferable to solventborne paint,” notes Jackie Murphy, technical specialist for Pavement Markings with BASF. “Waterborne polymer-based paints are more environmentally benign than solvent-based paints and easier to apply than other technologies, such as thermoplastic paints,” she adds. Senior research scientist Eric Greyson with Dow Coating Materials notes that the vast majority of resins used in waterborne traffic paint are 100% acrylic emulsions. All-acrylic products have superior resistance to yellowing and are formulated with fast-drying technology for durable and long-lasting traffic paints. They are also formulated to impart excellent latex and paint stability, agrees Murphy. Other chemistries, according to Greyson, such as alkyds and polyurethane dispersions, dry slowly and lack the hydrolytic stability and/or weatherability required for this application. Styrene acrylic materials that contain drying aids and high solids latexes are also used, according to Joy Gallagher, North America marketing manager for Traffic at Dow Coating Materials. Mike Law, regional marketing manager for APAC at allnex adds that two-component peroxide-cured UPE and MMA-based systems, epoxies, and urethanes are used for highly specialized applications.
Most traffic paints are applied by state, municipal, and federal departments of transportation (DOTs) and are highly specified based on performance and composition needs, according to Ron Grieb, application development leader for Coating Resins–Americas at Arkema. For instance, he notes that solvent-based acrylics are used during the shoulder seasons or in climates where relative humidity is higher and temperatures are lower to maintain fast-drying characteristics. On the other hand, waterborne acrylic paints offer fast-dry coatings that are highly durable and can be easily applied. Alkyds, meanwhile, are used in zone markings where compositional specifications are not a limitation, and a crew can cone off a parking lot overnight. “While a number of chemistries are used, the determination of which one is best is mainly dependent on both the applied cost, performance needs, and compliance rules adopted in each region or country,” says Law. “The calculations of lifecycle cost are based on both durability and reduction in road deaths, although the latter is less likely to be considered in emerging countries,” he comments.
There are several drivers for the development of new resin technologies for the formulation of traffic paints. Number one is enhancing driver safety, according to Gallagher. In addition to injury reduction, most new road marking technologies are linked to road tolls, adds Law. “In many countries the annual toll is highly politicized, so there typically is a focus on developing effective line marking systems that strongly contribute to improved outcomes,” he notes. Other drivers include supporting infrastructure for autonomous vehicles, improving the cost-per-mile, maintaining retroreflectivity, the shift to high-durable markings, and VOC reduction, according to Grieb. Beyond greater durability, Greyson observes that there is a need for the ability to stripe at low temperatures. Technologies that can increase the speed of construction and can also extend the construction season beyond what is traditionally allowed help to reduce costs and improve safety conditions for contractors, adds Murphy. Fast-drying characteristics are also of utmost importance to ensure a quick bond and prevent any early tracking or water wash-off, she says.
The best way to measure paint performance is to apply coatings to the road and monitor their performance, and the most efficient way to do this is through transverse test decks.
There is, however, a fine line between drying too quickly (over reactive, less stable) and drying too slowly (unreactive, over stable). “Having the right chemistry of the resin designed for specific paint formulations is a key element of successful product development,” Murphy asserts. She also remarks that a particular challenge is to get consistently good performance over a range of different paint formulations. This difficulty is compounded by the fact that lab tests tend to do a poor job of predicting or correlating to real world performance for traffic paints and coatings, according to Greyson. Gallagher adds that the best way to measure paint performance is to apply coatings to the road and monitor their performance, and the most efficient way to do this is through transverse test decks. “Monitoring does, however, take significant time and resources to gain data critical to understanding performance,” she says. As a result, most companies rely solely on lab testing, and only conduct field tests for a few new systems per year. Dow, Greyson notes, has made major investments to create an unparalleled field trial operation that tests several hundred new products every year and takes into account location, road conditions, temperature, and additional factors known to impact durability.
Like all other paints and coatings, traffic marking paints must be compliant with the applicable environmental regulations where they are applied, adds Grieb. He also points out that it is necessary to ensure that the striping trucks are compatible with the specific marking technology being used. “Solventborne paint trucks are not compatible with waterborne paint. Specially designed equipment is also needed for the application of thermoplastic resins and structured markings,” he explains.
An overarching challenge the industry faces today is the difficulty in funding roadway improvement projects, according to Gallagher. “Since the early 2000s, the United States has been spending more out of the Highway Trust Fund (HTF) than what has been collected primarily through gas and diesel taxes, which have not increased since 1993 or been adjusted for inflation. Additionally, the FAST Act (Fixing America’s Surface Transportation Act) is set to expire in 2020, and its reauthorization will require an additional $100 billion in new revenue,” she says. Gallagher expects states to reduce their bidding as expiration of the FAST Act approaches because they continually face resource constriction even when federal funds are available.
Another challenge is created by the approval process for traffic marking paints. In the United States, each state DOT and the federal DOT have their own standards and specifications. Similarly, other countries have their own requirements as well. “With such a wide variety of standards between countries and states within countries, gaining approvals is often expensive and time consuming,” states Law. In the United States, some states procure paint through bulk contracts. In this circumstance, the DOT sets a standard, and purchases are based on prices for bids meeting that standard, according to Greyson. Furthermore, some states establish very detailed specifications regarding what ingredients can be used and in what percentages in a formulation, which is a very restrictive approach. Other standards are largely performance-based. In some cases, contractor purchasing decisions may be limited or guided by a list of paints approved by the state or relevant road authority, but may also vary in how highly they value dry time, batch-to-batch consistency, or other productivity factors, Greyson notes. The Federal Aviation Administration (FAA) also has its own requirements for marking paints used on airport runways, according to Larry Boise, co-owner of Franklin Paint Company.
The state DOTs are driven by two primary concerns: cost and safety.
According to Jeff Lackey, corporate technical director at Diamond Vogel, it is important to understand that the state DOTs are driven by two primary concerns: cost and safety. “On the cost side, due to tight state budgets, state DOTs primarily make the selection a bid process; the lowest bid that meets the specs wins the contract,” he says. With this competitive bid process, purchasing decisions are often made by procurement departments that are solely focused on saving money, according to Boise. “These decisions are generally made without knowledge of differences in performance and without conducting a full cost-benefit analysis that takes into account truck down-time, the frequency of painting, and other important factors,” he explains. This bidding process, therefore, often leads states to miss out on innovations, observes Greyson. “The quality of polymers has dramatically improved since the inception of quick-dry waterborne traffic paint, and states that are focused on saving a few cents per gallon of up-front cost will miss out on the significant long-term savings these new products can provide, even within the first year,” he says. He notes that some states are more proactive about staying aware of innovations and updating specifications to ensure their residents reap the benefits.
Because safety is their primary functional concern about traffic paint, many DOTs have very restrictive specifications. DOTs take this approach because they have used marking coatings with certain requirements and are comfortable that these types of products will perform in the field, according to Lackey. “The problem with this approach is that it can stifle innovation on the coatings supplier side and also deter polymer suppliers from developing new innovative resins for this market,” he asserts. As an example, Lackey notes that if a coatings company develops a way to get higher visibility/reflectivity/brightness with a formulation that uses less TiO2 than the state spec requires, the coating will not be accepted. “To get such a new product adopted, the manufacturer must work closely with the DOTs to change their specs, which is very challenging because the DOTs see such changes as safety issues where risks should not be taken lightly,” he observes.
For the market to adopt a new technology, Gallagher says there needs to be an attribute of that technology that appeals to the market. Manufacturers of raw materials and formulated coatings, adds Greyson, must proactively communicate innovation to the DOTs to influence the adoption of new technologies. “There are numerous conferences and opportunities for manufacturers and DOTs to discuss these innovations and to run trials,” he notes. One example is through the American Association of State Highway and Transportation Officials (AASHTO) National Transportation Product Evaluation Program. He also notes that patience is essential. “There is no real substitute for applying paints to the road and waiting a year or two to see the outcome. For a new material, it is important to perform a number of demonstrations to ensure that a single good result isn’t a fluke. If you want to drive change, you need to be patient and learn to effectively communicate,” Greyson states. Lackey agrees: “For a coatings manufacturer, it is all about developing relationships and credibility with the decision makers in the DOTs to introduce new technologies. Many states are very open to this, with the mutual understanding that it may take at least one or two years of demonstrating real-world performance before any changes can be made.” Boise adds that it is important for DOTs and contractors to keep an open mind about new technologies and understand that there will be some hiccups as new products are introduced. “If everyone works together, these early issues can be resolved, and the ultimate result will be the use of better traffic paints that help ensure the safety of drivers,” he states.
Some changes are on the way. With autonomous vehicles on the horizon, road authorities must support both the human driver of today and the machine driver of the future. That requires improvement of the uniformity of lane markings across the country and the ability for machine vision systems (e.g., cameras) to interact with the lines, according to Gallagher. “One way to accomplish this goal is to increase the striping line width from 4 in. to 6 in. and to use high-quality waterborne paint.” As the population ages, the wider lines will also make road markings more conspicuous for the growing percentage of older drivers on the roadways, according to Boise.
Another critical issue under discussion relates to the impact of specific polymer types on the performance of traffic marking paints. “Given that the polymer type is the single most important factor in determining paint durability, knowing which polymer is in a paint and understanding how to confirm its identity is essential,” Greyson asserts. Dow is partnering with AASHTO and other associations to help states understand the importance of polymers and choosing paints that contain the polymer they desire. “Requiring unique methods to identify the polymers in traffic coatings will help traffic engineers and contractors ensure that the paints used on their test decks are the same products that have been approved and delivered to their states,” Gallagher asserts.
For a coatings manufacturer, it is all about developing relationships and credibility with the decision makers in the DOTs to introduce new technologies.
Another significant development observed by Greyson is that increasing numbers of states are realizing that buying the absolute lowest-cost materials is not often the most cost-effective solution. While there is not yet any apparent desire to change from the current competitive bid system, the movement toward the use of performance-based vs formula-based specifications is an important development to Lackey. “Traffic paint can be one of the lower margin products in the industry due to the nature of the competitive bid process for contracts. On the other hand, traffic coatings require a significant amount of complex technology and quality control is stringent. As more state DOTs move to performance-based specifications rather than dictate types and percentages of ingredients, we anticipate reduction of the restrictions currently in place on certain types of innovation,” he explains.
Separately, a new ruling expected in late 2019 from the Federal Highway Administration in the United States on minimum retroreflectivity for pavement markings may encourage some agencies to revisit their practices and more actively explore new technologies that may help them meet these requirements more economically, according to Greyson.
With respect to new traffic marking paint technologies, Murphy notes that the most significant developments in recent years have been the introduction of fast-drying properties for quicker construction and improved scrub resistance for extending paint performance and lifespan. “The industry has gotten better at providing products that have better storage stability yet dry fast only when being applied,” she says. BASF, for instance, developed a proprietary QUICK-TRIGGER® chemistry that is both stable and fast drying. The company’s newest polymer for traffic paints is ACRONAL® Xpress 4347, which, according to Murphy, can easily be used in most existing water-based traffic paint formulations on the market today and provides application stability along with scrub resistance. Allnex, meanwhile, has developed a fast-set, water-based acrylic with much quicker development of early shower wash-out resistance, greatly expanding the length of the line marking season for contractors, according to Law.
Requiring unique methods to identify the polymers in traffic coatings will help traffic engineers and contractors ensure that the paints used on their test decks are the same products that have been approved and delivered to their states.
Dow’s waterborne FASTRACK 5408™ resin is a new polymer that provides superior durability at standard film builds and can be applied at temperatures as low as 35°F, expanding the striping season, according to Greyson. “The superior performance of this polymer comes from a new polymer architecture that seems to improve the ability of the paint to absorb and dissipate the energy from stressors that create mechanical failure in previous generations of polymers,” he notes. Dow has conducted over 30 road trials (both transverse and longitudinal), including comparisons to industry standard controls, and shown that the FASTRACK 5408 emulsion outperforms existing technologies, according to Gallagher. Diamond Vogel has used this resin technology, partnering with Dow and various state DOTs (as it would with any new technology) to discuss its advantages. “We have made production level batches for testing, coordinated test deck evaluation with the DOTs, provided feedback to Dow so the technology can be further improved, and worked with the DOTs to address any performance issues they may have,” Lackey says. “As importantly,” he adds, “Diamond Vogel provides the DOTs with a level of confidence that we will stand behind and strongly support any new technology that we introduce to them and rapidly address any issues they may see in the field.”
For solventborne applications, Arkema recently introduced SYNOLAC Versa high-solids alkyd resins that offer the performance of conventional alkyds in low-VOC formulations. “These products make up a solventborne alkyd platform that allows for higher molecular weight at lower viscosity, providing faster hardness build than typical alkyd resins,” Grieb says.
Franklin Paint worked closely with the FAA to obtain approval of a methyl methacrylate paint designed for use on the movement side of airports. “We first had the coating tested at FAA’s lab in Atlantic City and then worked closely with the FAA in Washington, D.C. to ultimately receive approval. It was a long process that took approximately eight years,” Boise says.
The most significant developments in recent years have been the introduction of fast-drying properties for quicker construction and improved scrub resistance for extending paint performance and lifespan.
Increasing use of specialized line marking systems with a focus on road toll reduction is of note for Law. As an example, he points to growing use of two-component methyl methacrylate-based audio tactile “RIBS” systems designed to alert drivers if they move out of their lanes. There has also been a move to UV-cure technologies, which greatly decrease the time needed to return to service, according to Law. Advances in the development of structured markings for improved wet retroreflectivity have also been important, according to Grieb. “With conventional paint markings, water can sit on top. Because the refractive index of water is too close to that of the glass beads in the paint, light is not reflected back to driver when the paint is wet. With the structured markings, water can flow off, allowing the glass beads to refract light and maintain wet retroreflectivity,” he explains.
Clearly, while adoption of new traffic marking materials can be a slow process, new technologies have been and continue to be developed by both resin manufacturers and coating formulators. The challenging nature of the market has limited the number of players, but those companies involved in the sector are committed to providing high-performance products. “There is a reason there are many fewer coatings companies in the traffic marking business than there are in most other markets,” states Lackey. The bid nature makes the cost requirements a challenge, the lengthy specification requirements result in a slow adoption of significantly new technologies, and simple things like the dry time required are often a surprise for companies investigating entering this business, he notes. “Those of us in this market, however, take a lot of pride in knowing that our products are contributing to the safety of millions of drivers every day,” Lackey concludes.
CoatingsTech | Vol. 16, No. 4 | April 2019