UV Absorber UV-360 in high-solids and powder coating formulations

UV Absorber UV-360 in High-Solids and Powder Coating Formulations: A Comprehensive Overview

Introduction

In the world of coatings, where durability meets aesthetics, ultraviolet (UV) light is often the invisible villain. It may be invisible to the naked eye, but its long-term effects on coating systems can be anything but subtle — fading, chalking, cracking, and loss of gloss are just a few of the unsightly symptoms. To combat this silent degradation, formulators have turned to UV absorbers — chemical compounds designed to soak up harmful UV radiation before it wreaks havoc on the coating’s molecular structure.

One such compound that has gained significant traction in both high-solids and powder coating applications is UV Absorber UV-360, also known by its chemical name 2-(2H-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol. In this article, we’ll dive deep into what makes UV-360 so effective, how it integrates into modern coating systems, and why it’s become a go-to solution for manufacturers aiming to extend the life of their products.

So, buckle up — we’re about to take a scenic drive through the chemistry of UV protection, with a pit stop at formulation science and a final destination at real-world performance.

1. What Is UV Absorber UV-360?

UV-360 belongs to the benzotriazole family of UV stabilizers — a class of organic molecules known for their ability to absorb UV light in the 300–380 nm range. This wavelength spectrum is particularly damaging to many organic polymers used in coatings, especially when exposed outdoors.

The molecular structure of UV-360 allows it to act like a sponge for UV photons. When these photons hit the molecule, they’re absorbed and then dissipated as harmless heat energy. This process prevents the initiation of photochemical reactions that lead to polymer degradation.

Key Features of UV-360:

Property	Description
Chemical Name	2-(2H-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol
Molecular Weight	~491 g/mol
CAS Number	1843-05-6
Appearance	Light yellow solid or powder
Solubility in Water	Insoluble
Recommended Dosage	0.5–2.0% by weight (varies by system)
UV Absorption Range	300–380 nm
Compatibility	Good with most resins, including polyesters, epoxies, and acrylics

UV-360 stands out among benzotriazoles due to its high molecular weight, which reduces volatility and migration within the coating film. This makes it particularly suitable for powder coatings, where low volatility is crucial during curing processes.

2. The Role of UV Absorbers in Coatings

Before we delve deeper into UV-360’s role, let’s take a moment to understand why UV protection matters in coatings.

When UV light strikes a polymer surface, it can break chemical bonds through a process called photodegradation. This leads to chain scission and crosslinking, ultimately causing:

Yellowing or color fading
Chalking (surface powdering)
Loss of mechanical strength
Cracking and flaking

To prevent this, UV absorbers like UV-360 are added to coating formulations. They work by intercepting UV photons before they reach the polymer backbone, thereby reducing the rate of degradation.

But UV absorbers aren’t the only players in the game. There are also hindered amine light stabilizers (HALS), which don’t absorb UV light directly but instead quench free radicals formed during photodegradation. Often, UV-360 is used in combination with HALS for a synergistic effect — think of them as Batman and Robin in the fight against UV damage.

3. Why Use UV-360 in High-Solids and Powder Coatings?

Coatings come in various forms — solvent-based, waterborne, high-solids, and powder. Each has its own set of challenges and advantages. Let’s explore why UV-360 shines in high-solids and powder coatings specifically.

3.1 High-Solids Coatings

High-solids coatings are formulated to contain less than 15–20% volatile organic compounds (VOCs), making them more environmentally friendly than traditional solvent-based systems. However, formulating high-solids coatings comes with technical hurdles, such as increased viscosity and reduced flowability.

UV-360 fits well into this environment because:

It has low volatility, which is essential when minimizing VOC emissions.
It shows good compatibility with high molecular weight resins commonly used in high-solids systems.
It doesn’t interfere with the crosslinking chemistry typical of these coatings (e.g., epoxy-polyester or acrylic-melamine systems).

Moreover, UV-360 retains its UV-absorbing capability even at high film thicknesses, which are common in industrial and automotive coatings.

3.2 Powder Coatings

Powder coatings are applied as dry powders and cured under heat, resulting in a durable, solvent-free finish. Because there’s no solvent involved, all components must survive the melting and curing stages without volatilizing.

Here’s where UV-360 truly excels:

Low volatility: Unlike some lower molecular weight UV absorbers, UV-360 doesn’t evaporate during the curing stage (typically around 180–200°C).
Thermal stability: Maintains integrity during melt mixing and curing.
Non-yellowing: Doesn’t contribute to discoloration after prolonged exposure, a key concern in architectural and appliance coatings.

A study by Zhang et al. (2020) demonstrated that UV-360 significantly improved the weather resistance of polyester-based powder coatings, with samples showing minimal gloss reduction and color change after 1000 hours of accelerated weathering testing.¹

4. How to Incorporate UV-360 into Coating Formulations

Adding UV-360 isn’t just a matter of tossing it into the mixer. Like any good ingredient in a recipe, it needs to be introduced at the right time, in the right way.

4.1 For High-Solids Coatings

In liquid systems, UV-360 is typically dissolved in a compatible solvent or resin before being blended into the main formulation. Since it’s not water-soluble, care must be taken in waterborne systems — though microencapsulation or dispersants can help.

Key steps:

Pre-dissolve UV-360 in a reactive diluent or co-solvent.
Add during the let-down phase to avoid thermal degradation.
Ensure homogeneity through proper mixing.

4.2 For Powder Coatings

In powder systems, UV-360 is usually added during the extrusion phase. Due to its high melting point (~170°C), it should be fed into the extruder after the resin has melted to ensure uniform dispersion.

Best practices:

Blend with other additives (like HALS or antioxidants) before extrusion.
Maintain processing temperatures below 120°C during grinding to prevent premature decomposition.
Monitor particle size distribution post-grinding to ensure even application.

A comparative study by Lee & Park (2018) found that UV-360 showed better retention of UV protection properties compared to other benzotriazoles when subjected to repeated thermal cycles in powder coatings.²

5. Performance Benefits of UV-360

Now that we’ve covered how to use UV-360, let’s talk about what it actually does for your coating.

5.1 Protection Against Fading and Discoloration

One of the most visible signs of UV damage is color fade. UV-360 helps preserve pigments by absorbing UV light before it reaches the chromophores in the pigment molecules.

In a test conducted by BASF (2017), coatings containing UV-360 showed up to 40% less color change after 2000 hours of QUV exposure compared to coatings without UV protection.³

5.2 Increased Longevity of Coating Films

By slowing down the degradation process, UV-360 extends the service life of coatings — especially important in outdoor applications like automotive parts, agricultural equipment, and architectural panels.

5.3 Synergy with Other Stabilizers

As previously mentioned, UV-360 works best when combined with HALS. The former absorbs UV light; the latter scavenges free radicals. Together, they offer a two-pronged defense mechanism.

This synergy was confirmed in a joint study by Clariant and DSM (2019), which showed that a combination of UV-360 and Tinuvin 770 extended the outdoor durability of polyester powder coatings by over 30% compared to using either additive alone.⁴

6. Comparative Analysis: UV-360 vs. Other UV Absorbers

Let’s put UV-360 in perspective by comparing it with some of its competitors in the UV absorber arena.

Parameter	UV-360	UV-327	UV-326	UV-234
MW (g/mol)	~491	~384	~346	~214
Volatility	Low	Medium	Medium	High
Thermal Stability	Excellent	Good	Fair	Poor
UV Absorption Range	300–380 nm	300–360 nm	300–360 nm	280–345 nm
Color Stability	Good	Moderate	Moderate	Poor
Cost	Moderate	Low	Low	Moderate
Typical Use	High-solids, powder	General purpose	Automotive	Food contact

From this table, it’s clear that UV-360 wins in terms of thermal stability and low volatility, making it ideal for powder coatings and high-temperature applications. UV-327 and UV-326 are cheaper alternatives but tend to migrate and yellow over time. UV-234, while effective in food-contact applications, lacks the robustness needed for industrial coatings.

7. Regulatory and Environmental Considerations

With increasing environmental scrutiny, the safety profile of additives like UV-360 is under constant review.

UV-360 is generally considered safe under current regulations, though it is classified as hazardous to aquatic life with long-lasting effects. Therefore, proper disposal and containment measures are recommended.

In Europe, UV-360 is listed under REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) and does not currently appear on the list of substances of very high concern (SVHC). In the U.S., it is not listed under California Proposition 65.

However, ongoing research into endocrine disruption and bioaccumulation potential means that future regulatory changes could affect its usage. As always, staying updated with local and international regulations is key.

8. Case Studies and Real-World Applications

Nothing speaks louder than results from the field. Here are a few examples of how UV-360 has been successfully implemented in real-world coating systems.

8.1 Automotive Refinish Coatings

An OEM paint supplier in Germany reported a 25% increase in gloss retention after incorporating UV-360 into their high-solids clearcoat system. The addition also led to a noticeable improvement in stone chip resistance, likely due to the overall stabilization of the polymer network.⁵

8.2 Architectural Aluminum Powder Coatings

In a project involving aluminum window frames exposed to Mediterranean sunlight, coatings with UV-360 showed no visible chalking or color shift after five years, whereas control samples began degrading within two years.

8.3 Industrial Equipment Coatings

A major machinery manufacturer in Japan switched from UV-327 to UV-360 in their high-temperature powder coatings. The result? Reduced yellowing during storage and improved color consistency across batches.

9. Challenges and Limitations

While UV-360 is an excellent performer, it’s not without its drawbacks.

Limited solubility in waterborne systems – requires careful formulation techniques.
Costlier than some alternatives – may be a barrier in cost-sensitive markets.
Not a standalone solution – works best in combination with HALS and antioxidants.
Requires precise dosing – too little won’t protect, too much can cause blooming or reduce clarity in clearcoats.

Also, UV-360 cannot protect against visible light or infrared radiation, so it’s not a miracle worker in every scenario.

10. Future Outlook

As sustainability becomes increasingly important, the demand for eco-friendly, durable coatings will continue to rise. UV-360, with its strong performance and adaptability to low-VOC and powder systems, is well-positioned to remain a key player in the UV protection market.

Researchers are already exploring ways to enhance its performance further, including:

Microencapsulation to improve dispersion in aqueous systems
Hybrid formulations combining UV-360 with HALS and antioxidants in single packages
Bio-based derivatives to reduce environmental impact

And who knows — maybe one day we’ll see UV-360 paired with nanotechnology for next-level protection 🚀.

Conclusion

In summary, UV Absorber UV-360 is a versatile and effective tool in the coatings chemist’s arsenal. Whether you’re formulating high-solids coatings for automotive finishes or powder coatings for architectural applications, UV-360 offers a winning combination of UV protection, thermal stability, and compatibility.

It may not wear a cape, but in the battle against UV-induced degradation, UV-360 is definitely a superhero 🦸‍♂️.

Just remember — like any good sidekick, it works best when teamed up with others (HALS, antioxidants) and used in the right context (dosage, formulation method, application type). With the right approach, UV-360 can help your coatings stand tall and shine bright — even under the harshest sun.

References

Zhang, L., Wang, Y., & Liu, H. (2020). Performance evaluation of UV absorbers in polyester powder coatings. Journal of Coatings Technology and Research, 17(4), 893–902.
Lee, K., & Park, J. (2018). Thermal stability and UV protection efficiency of benzotriazole-type UV absorbers in powder coatings. Progress in Organic Coatings, 123, 112–119.
BASF Technical Bulletin (2017). UV Protection in High-Solids Coatings Using UV-360. Ludwigshafen, Germany.
Clariant & DSM Joint Study (2019). Synergistic Effects of UV-360 and HALS in Outdoor Durable Powder Coatings. Zurich, Switzerland.
European Coatings Journal (2021). Case studies in automotive refinish coatings with UV-360. Issue 3, pp. 44–49.

Got questions? Want to geek out over UV spectra or discuss HALS synergy? Drop me a line — I’m always ready to dive deeper into the colorful world of coatings! 😊

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