Application of Jinan Tonex Chemical's Fluorescent Brightener OB in Hot-Melt Road Markings

Available data show that hot-melt roadmarking coatings are a type of advanced

traffic safety marking material thatgradually gained global popularity in the late 1960s. I China, research on hot-melt coatings has also undergone years of development,

including exploratory studies, laboratory testing, and field applications, leading to significantprogress. Eventually, hot-melt coatings were officially designated as astandard

road marking material, with national technical standards established.Today, hundreds of cities in China have adopted hotmelt coatings,demonstrating promising growth prospects.In hotmelt coatings, fluorescentbrighteners, though added in small amounts, play a crucial role by enhancingwhiteness, brightness, and durability.

Traditionally, titanium dioxide (TiO₂) was used for whitening, but relyingsolely on TiO₂ often yielded unsatisfactory results. This is becauseTiO₂ provides only physical whitening, and once a certainwhiteness level is reached, additional amounts become wasteful. This is wherefluorescent brighteners come into play.

However, there are thousands offluorescent brighteners in the industrywhich one is best suited for hot-meltcoatings?

Hot-melt coatings have three key requirements:

1.     High-temperature resistance—the brightener must withstand at least200°C.

2.     Anti-yellowing—the coating should not yellow afterprolonged sun exposure

3.     Cost-effectiveness—the solution must be economicallyviable.

Fluorescent Brightener OB meets all three criteria.

By leveraging optical principles,Fluorescent Brightener OB absorbs yellow light and emits blue light, instantlyincreasing the coating's whiteness by over 15%. This not only reduces therequired amount of TiO₂ but also delivers superior results. OBoffers outstanding whitening and brightening effects, along with exceptionalweather resistance—features that other brighteners cannot match.

1. Characteristics of Hot-Melt Coatings and WhiteningRequirements

·       High-Temperature Resistance: Hot-melt coatings require processing temperatures of 180–220°C,

so additives must remain stable withoutdecomposition. OB’s thermal stability (≥200°C) fulfills this need.

·       UV Resistance: Road markings are constantly exposed to sunlight, requiring

resistance to UV-induced yellowing.

OB absorbs UV lightand re-emits blue light, delaying photodegradation.

·       Cost Efficiency: Traditional TiO₂ requires 5–10% loading for optimalwhiteness,

where as OB achieves a 15%+whiteness boost at just 0.01-0.05%,reducing material costs.

2. Key Advantages of Fluorescent Brightener OB

·       Optical Whitening   OB absorbs UV light (300–400 nm) and emits blue-violet light (420–450 nm),neutralizing yellow tones and improving perceived whiteness

(CIE whitenessindex).

·       Weather Resistance Data: Tests show that hot-melt coatings with OB retain >90%

whiteness after QUV accelerated aging (equivalent to 6 monthsoutdoors), while TiO₂-only samples lose 20–30% whiteness.

·       Synergy with TiO₂: TiO₂ scatters light for physical whitening,while OB provides chemical whitening via fluorescence. Combined, they reduceTiO₂ usage by 30-50% while

achieving whiteness levels above 80.

3. Comparison with Other Brighteners

·       Temperature Resistance: Common brighteners like CBS (stable upto ~160°C) decompose during hot-melt processing, while OB-1 (220°C) and KSN(250°C) are more heat-resistant but cost 2–3 times more than OB.

·       Cost-Effectiveness: Priced at ~¥150–200/kg and dosed atonly 50–100g per ton

of coating, OB is more economical than increasing TiO₂ or using premium brighteners.

4. Practical Application Guidelines

·       Mixing Process: Add OB during the molten phase(180–200°C) for uniform dispersion. Avoid direct contact with strong oxidizers(e.g., ammonium persulfate).

·       Formula Optimization: Recommended TiO₂/OB ratio (e.g., 4% TiO₂ + 0.03% OB) balances cost andperformance.

·       Regulatory Compliance: OB meets REACH and China’s GB 9685standards, with no heavy metal migration risks, making it safe for roadmarkings.

5. Market Outlook

With rising demand for durable roadmarkings (e.g., per China’s updated GB/T 16311-2022 standard),high-performance additives like OB will see growing adoption. Jinan TongyiChemical’s OB, offering competitive pricing and stability, is well-positionedto replace imported brands (e.g., BASF’s OB) in municipal and highway projects.