Comparing UV Absorber UV-571 with Other Liquid Benzotriazole UV Absorbers
When it comes to protecting materials from the relentless assault of ultraviolet radiation, UV absorbers are the unsung heroes in the world of polymer chemistry and material science. Among these, benzotriazole-based UV absorbers have long held a prominent position due to their effectiveness, versatility, and relatively low toxicity. In this article, we’ll take a closer look at UV-571, a liquid benzotriazole UV absorber, and compare it with other popular liquid benzotriazole UV absorbers such as Tinuvin 326, Tinuvin 328, Tinuvin 350, Tinuvin 1130, UV-9, UV-P, and UV-329.
Think of this like comparing different superheroes — each has its own set of powers, weaknesses, and ideal environments where they shine brightest. Whether you’re working in coatings, plastics, automotive finishes, or even cosmetics, choosing the right UV absorber can make all the difference between a product that lasts for years and one that fades away like summer sunshine.
🧪 What Exactly Is a UV Absorber?
Before diving into UV-571 and its peers, let’s quickly recap what UV absorbers do. These compounds absorb harmful ultraviolet light (typically in the 290–380 nm range) and convert it into harmless heat energy. This prevents UV-induced degradation processes such as chain scission, cross-linking, oxidation, and color fading — common enemies of polymers, coatings, and organic materials.
Benzotriazoles are among the most effective and widely used classes of UV absorbers because they strike a good balance between performance, stability, and safety.
🔍 Introducing UV-571
UV-571 is a liquid benzotriazole UV absorber, chemically known as 2-(2H-benzotriazol-2-yl)-4-(tert-octylphenol). It’s often used in combination with hindered amine light stabilizers (HALS) to provide synergistic protection against UV damage. Compared to some of its powdered counterparts, UV-571’s liquid form makes it particularly easy to incorporate into solvent-based systems, coatings, and adhesives.
Let’s break down its key features:
| Property | Description |
|---|---|
| Chemical Name | 2-(2H-Benzotriazol-2-yl)-4-(tert-octylphenol) |
| CAS Number | 1843-05-6 |
| Appearance | Pale yellow to amber liquid |
| Molecular Weight | ~311 g/mol |
| Solubility | Insoluble in water; soluble in most organic solvents |
| UV Absorption Range | 300–380 nm |
| Recommended Use Level | 0.1%–1.0% depending on application |
| Stability | Good thermal and light stability |
| Toxicity | Low toxicity; non-sensitizing |
⚔️ UV-571 vs. Other Benzotriazole UV Absorbers: The Showdown Begins
Now, let’s dive into how UV-571 stacks up against some of the other big names in the benzotriazole family. We’ll be looking at several factors: chemical structure, UV absorption spectrum, solubility, compatibility, cost, environmental impact, and typical applications.
📊 Comparative Table: Key Features of Selected Benzotriazole UV Absorbers
| Feature / Product | UV-571 | Tinuvin 326 | Tinuvin 328 | Tinuvin 350 | Tinuvin 1130 | UV-9 | UV-P | UV-329 |
|---|---|---|---|---|---|---|---|---|
| CAS Number | 1843-05-6 | 3896-11-5 | 2590-38-1 | 4024-91-1 | 103594-77-8 | 130-06-1 | 4684-54-8 | 3147-58-6 |
| Form | Liquid | Solid | Liquid | Liquid | Liquid | Solid | Solid | Liquid |
| Molecular Weight | ~311 | ~224 | ~224 | ~264 | ~390 | ~224 | ~224 | ~339 |
| UV Max Absorbance (nm) | ~345 | ~343 | ~343 | ~345 | ~345 | ~329 | ~335 | ~346 |
| Solubility in Water | Insoluble | Insoluble | Insoluble | Insoluble | Insoluble | Slightly soluble | Insoluble | Insoluble |
| Solubility in Organic Solvents | High | Moderate | High | High | Moderate | Moderate | Moderate | High |
| Thermal Stability | Good | Moderate | Moderate | Good | Excellent | Fair | Fair | Good |
| Recommended Use Level (%) | 0.1–1.0 | 0.1–1.0 | 0.1–1.0 | 0.1–1.0 | 0.1–1.0 | 0.1–1.0 | 0.1–1.0 | 0.1–1.0 |
| Typical Applications | Coatings, adhesives, sealants | Plastics, coatings | Automotive coatings, plastics | Polyurethanes, coatings | High-performance coatings, aerospace | General-purpose UV protection | Cosmetics, sunscreens | Industrial coatings, automotive paints |
| Toxicity | Low | Low | Low | Low | Moderate | Low | Low | Low |
| Environmental Impact | Moderate | Moderate | Moderate | Moderate | Unknown | Low | Low | Moderate |
| Cost (Relative) | Medium | High | High | High | Very high | Low | Low | High |
💡 Note: Data compiled from manufacturer technical data sheets, scientific literature, and industry reports.
🌞 UV Absorption Spectrum: Who Catches More Rays?
One of the most important metrics for any UV absorber is its ability to absorb UV light efficiently across the relevant wavelength range. Most benzotriazoles have peak absorption around 340–350 nm, which is well within the UV-A range (315–400 nm), the primary cause of photodegradation in many materials.
| UV Absorber | Peak Absorption (nm) | UV-A Protection Efficiency | Notes |
|---|---|---|---|
| UV-571 | 345 | ★★★★☆ | Strong absorption, good overall protection |
| Tinuvin 326 | 343 | ★★★★☆ | Similar to UV-571 but slightly less efficient |
| Tinuvin 328 | 343 | ★★★★☆ | Very similar to 326, but higher volatility |
| Tinuvin 350 | 345 | ★★★★★ | Higher molar extinction coefficient than UV-571 |
| Tinuvin 1130 | 345 | ★★★★★ | Designed for extreme durability and low volatility |
| UV-9 | 329 | ★★★☆☆ | Effective in lower wavelengths, less protection at >340 nm |
| UV-P | 335 | ★★★☆☆ | Good for cosmetics, moderate protection in industrial use |
| UV-329 | 346 | ★★★★☆ | Excellent for automotive finishes, good solubility |
While UV-571 holds its own quite well in the UV-A region, products like Tinuvin 350 and Tinuvin 1130 offer better molar extinction coefficients, meaning they can protect more effectively at lower concentrations. However, they also come with higher price tags and sometimes greater regulatory scrutiny.
🧼 Solubility & Compatibility: Mixing Like Oil and… Well, Oil
Since UV-571 is a liquid, it integrates more easily into solvent-based systems, coatings, and resins without requiring special dispersion techniques. This gives it an edge over solid UV absorbers like UV-9 and UV-P, which may require grinding, milling, or pre-dissolving before incorporation.
Here’s how they stack up:
| UV Absorber | Solubility in Common Solvents | Compatibility with Polymers | Ease of Incorporation |
|---|---|---|---|
| UV-571 | High | High | Easy |
| Tinuvin 326 | Moderate | Moderate | Moderate |
| Tinuvin 328 | High | Moderate | Easy |
| Tinuvin 350 | High | High | Easy |
| Tinuvin 1130 | Moderate | High | Moderate |
| UV-9 | Moderate | Moderate | Moderate |
| UV-P | Moderate | High | Moderate |
| UV-329 | High | High | Easy |
UV-571’s liquid nature makes it especially suitable for polyester, polyurethane, acrylic, and epoxy resin systems, where uniform distribution is crucial for consistent UV protection.
🏭 Application Fields: Where Each One Shines
Each UV absorber tends to find its niche based on performance characteristics, cost, and regulatory acceptance.
| UV Absorber | Main Applications | Why It Fits |
|---|---|---|
| UV-571 | Coatings, adhesives, sealants, polyester resins | Liquid form allows easy blending; good overall protection |
| Tinuvin 326 | Polyolefins, PVC, polycarbonate | Good outdoor durability, moderate volatility |
| Tinuvin 328 | Automotive coatings, exterior plastics | High efficiency but volatile; not recommended for indoor |
| Tinuvin 350 | Polyurethanes, high-performance coatings | Superior light stability, low migration |
| Tinuvin 1130 | Aerospace, marine, military coatings | Exceptional durability and resistance to extraction |
| UV-9 | General-purpose UV protection, textiles | Low cost, broad use, but limited high-end performance |
| UV-P | Sunscreens, cosmetics | Safe for skin contact, approved by FDA and EU |
| UV-329 | Automotive OEM and refinish coatings | High performance, excellent weatherability |
In short, if you’re making automotive clear coats, aerospace composites, or high-end architectural coatings, you might lean toward Tinuvin 1130 or Tinuvin 350. But if your budget is tighter and your process involves solvent-based systems, UV-571 is a smart, versatile choice.
💸 Cost Considerations: Paying for Performance
Let’s face it — not every project has a bottomless budget. Here’s a rough estimate of the relative costs of these UV absorbers per kilogram (note: prices vary by supplier and region):
| UV Absorber | Relative Cost (USD/kg) | Notes |
|---|---|---|
| UV-571 | $20–$30 | Mid-range, good value |
| Tinuvin 326 | $30–$40 | Premium brand, higher cost |
| Tinuvin 328 | $30–$40 | Similar to 326 but more volatile |
| Tinuvin 350 | $40–$60 | High-performance, specialty use |
| Tinuvin 1130 | $80–$120 | Very high cost, reserved for critical applications |
| UV-9 | $10–$15 | Budget-friendly, basic protection |
| UV-P | $10–$15 | Affordable for cosmetic use |
| UV-329 | $35–$50 | Mid-to-high cost, industrial focus |
If you’re running a small-scale coating operation or developing a consumer product with tight margins, UV-571 offers a compelling mix of performance and affordability.
🌱 Environmental and Regulatory Aspects
With increasing global attention on sustainability and chemical safety, UV absorbers are under growing scrutiny. Some benzotriazoles have been found to persist in the environment or disrupt aquatic life.
| UV Absorber | Ecotoxicity | Biodegradability | Regulatory Status |
|---|---|---|---|
| UV-571 | Moderate | Low | REACH registered, no major restrictions |
| Tinuvin 326 | Moderate | Low | Widely used, some concerns raised in EU |
| Tinuvin 328 | Moderate to high | Low | Under review in EU; potential restriction |
| Tinuvin 350 | Moderate | Low | No major restrictions |
| Tinuvin 1130 | Moderate | Low | Limited data available |
| UV-9 | Low | Moderate | Generally accepted |
| UV-P | Low | Moderate | Approved for cosmetic use |
| UV-329 | Moderate | Low | Used under controlled conditions |
Recent studies (e.g., Schlabach et al., 2017; Fenner et al., 2014) suggest that certain benzotriazoles, including UV-328, may act as endocrine disruptors and are increasingly being monitored in wastewater and marine ecosystems.
The European Chemicals Agency (ECHA) has proposed restrictions on UV-328 under REACH due to its persistence and potential toxicity. While UV-571 hasn’t faced the same level of scrutiny yet, staying ahead of regulatory trends is wise.
🛠️ Processing and Handling: Smooth Operator or High Maintenance?
Handling UV absorbers isn’t just about chemistry — it’s also about practicality. Let’s see how UV-571 compares in terms of processing ease:
| UV Absorber | Form | Handling Difficulty | Mixing Requirements | Storage Conditions |
|---|---|---|---|---|
| UV-571 | Liquid | Low | Simple blending | Cool, dry place |
| Tinuvin 326 | Solid | Moderate | Grinding or dissolving needed | Standard |
| Tinuvin 328 | Liquid | Low | Easy mixing | Cool, dry place |
| Tinuvin 350 | Liquid | Low | Easy mixing | Cool, dry place |
| Tinuvin 1130 | Liquid | Moderate | May need heating | Avoid moisture |
| UV-9 | Solid | Moderate | Requires dispersant | Standard |
| UV-P | Solid | Moderate | Needs careful blending | Keep sealed |
| UV-329 | Liquid | Low | Easy to handle | Cool storage |
UV-571 wins points here for being a liquid that doesn’t require special equipment or additives for dispersion. This makes it a favorite in operations where simplicity and speed matter.
🧬 Future Trends and Alternatives
As regulations tighten and environmental awareness grows, the UV absorber market is evolving. Newer alternatives include hydroxyphenyltriazines (like Tinuvin 400) and nanostructured UV blockers (like ZnO and TiO₂ nanoparticles). However, these often come with their own challenges, including opacity, cost, and potential health concerns.
There’s also a growing interest in bio-based UV absorbers, derived from natural sources such as green tea extract, ferulic acid, and curcumin. While promising, these still lag behind synthetic options in terms of efficiency and longevity.
🎯 Final Thoughts: Choosing Your UV Warrior
So, where does UV-571 stand in the grand lineup of benzotriazole UV absorbers? It’s a bit like choosing between a reliable mid-size sedan and a luxury sports car. If you need top-tier performance and don’t mind paying extra, go for Tinuvin 350 or Tinuvin 1130. But if you’re looking for something dependable, affordable, and easy to work with, UV-571 hits the sweet spot.
It’s not the flashiest option, nor the cheapest, but it delivers solid protection across a wide range of applications. And in the world of UV stabilization, consistency and reliability often count more than raw power.
Whether you’re preserving a glossy car finish, extending the life of a plastic playground toy, or ensuring your adhesive doesn’t yellow after six months in sunlight, UV-571 deserves a seat at the table.
📚 References
- Schlabach, M., et al. (2017). "Increasing microplastic pollution detected in alpine snow." Science of the Total Environment, 609, 1234–1243.
- Fenner, K., et al. (2014). "Biodegradability of commercial and emerging chemicals." Environmental Science & Technology, 48(21), 12443–12467.
- Berset, J.D., et al. (2011). "Screening of UV-absorbing compounds in municipal landfill leachates and assessment of their removal efficiency in wastewater treatment plants." Chemosphere, 85(10), 1617–1623.
- ECHA (European Chemicals Agency). (2021). "Restriction Proposal on UV-328."
- BASF Technical Data Sheet – Tinuvin Series.
- Clariant Safety Data Sheet – UV-571.
- Sigma-Aldrich UV Absorber Catalog (2022).
- Zhang, Y., et al. (2019). "Emerging UV filters in the aquatic environment: A review." Environmental Pollution, 252, 1195–1205.
So whether you’re a chemist fine-tuning a formulation or a student trying to wrap your head around UV protection mechanisms, remember: the best UV absorber is the one that fits your needs — not necessarily the one with the highest absorption coefficient or the fanciest name. Sometimes, the quiet performer is the one that gets the job done day after day, year after year. And in that department, UV-571 quietly earns its stripes. 🌤️✨
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