Protecting Injection-Molded Parts from UV Degradation with UV Absorber UV-928

Introduction: The Sun – A Silent Saboteur of Plastics

We all love the sun. It warms our skin, powers solar panels, and makes life on Earth possible. But for injection-molded plastic parts? The sun can be a real party pooper — or worse, a slow destroyer.

Ultraviolet (UV) radiation from sunlight may not be visible to the human eye, but its effects on polymers sure are. Fading colors, loss of mechanical strength, surface cracking, and even disintegration — these are the telltale signs that your once-sturdy plastic part has been sunbathed one too many times.

Enter UV-928, a powerful UV absorber designed specifically to protect plastics from the harmful effects of UV radiation. In this article, we’ll explore how UV-928 works, why it’s an essential additive in injection molding, and what parameters you should consider when using it. We’ll also compare it to other common UV stabilizers, discuss best practices for incorporation, and touch on some real-world applications where UV-928 has proven itself invaluable.

So, grab your sunscreen (metaphorically speaking), and let’s dive into the world of UV protection for injection-molded plastics.

Chapter 1: Why UV Protection Matters for Injection-Molded Plastics

The Invisible Enemy: How UV Radiation Damages Polymers

When UV light hits a polymer, it doesn’t just bounce off — it gets absorbed. This absorption kicks off a series of chemical reactions that break down the molecular structure of the material. Over time, this leads to:

Yellowing or color fading
Surface cracking (crazing)
Loss of impact resistance
Reduced tensile strength
Chalking and dusting

Polymers like polypropylene (PP), polyethylene (PE), polycarbonate (PC), and acrylonitrile butadiene styrene (ABS) are particularly vulnerable. Without proper stabilization, these materials can degrade within months of outdoor exposure.

💡 Think of UV radiation as a tiny army of molecular saboteurs — they don’t knock the wall down, but chip away at it until it crumbles.

Chapter 2: Meet UV-928 – Your Plastic’s New Best Friend

What is UV-928?

UV-928 is a hydroxyphenyl benzotriazole-type UV absorber known for its excellent performance in thermoplastics. Its chemical name is 2-(2H-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, which might sound intimidating, but its job is pretty straightforward: absorb UV light before it can wreak havoc on your polymer chains.

This compound is widely used across industries due to its compatibility with various resins, high efficiency in absorbing UV-A and UV-B radiation, and minimal impact on physical properties of the base polymer.

Chapter 3: Key Features and Technical Specifications of UV-928

Let’s take a closer look at what makes UV-928 tick.

Property	Value/Description
Chemical Name	2-(2H-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol
CAS Number	153233-15-7
Molecular Weight	~400 g/mol
Appearance	White to light yellow powder
Solubility in Water	Insoluble
Melting Point	~140°C
UV Absorption Range	300–380 nm (UV-A and UV-B)
Thermal Stability	Stable up to 300°C
Recommended Loading Level	0.1% – 1.0% by weight
Compatibility	Polyolefins, PVC, ABS, PC, PMMA, ASA, TPU, etc.
Regulatory Compliance	REACH, RoHS compliant; non-restricted under major regulations

📌 Pro Tip: UV-928 is often used in combination with HALS (hindered amine light stabilizers) for synergistic protection. Think of it as double armor against UV damage.

Chapter 4: How UV-928 Works – The Science Behind the Shield

Step-by-Step Mechanism

Absorption: UV-928 absorbs UV photons in the 300–380 nm range.
Energy Dissipation: The absorbed energy is converted into harmless heat through internal hydrogen bonding.
Molecular Stabilization: By intercepting UV energy early, UV-928 prevents the initiation of chain scission and oxidation reactions.
Long-Term Protection: Unlike sacrificial stabilizers, UV-928 remains effective over long periods without significant degradation.

🔬 In simple terms, UV-928 acts like a microscopic umbrella, shielding each polymer molecule from UV attack.

Chapter 5: Comparison with Other UV Stabilizers

While UV-928 is highly effective, it’s not the only player in town. Let’s see how it stacks up against other commonly used UV stabilizers.

Feature	UV-928	UV-327	UV-531	Tinuvin 328 (Benzotriazole)
UV Absorption Range	300–380 nm	300–380 nm	280–360 nm	300–380 nm
Heat Resistance	High	Medium	Medium	High
Color Stability	Excellent	Good	Moderate	Excellent
Cost	Moderate	Low	Moderate	High
Migration Resistance	High	Low	Medium	High
Common Applications	Automotive, electronics, outdoor goods	General-purpose plastics	Flexible films, coatings	High-performance industrial parts

As shown above, UV-928 offers a balanced profile — high UV absorption, good thermal stability, low migration, and moderate cost — making it ideal for a wide range of applications.

Chapter 6: Real-World Applications of UV-928

Case Study 1: Automotive Exterior Components

Automotive manufacturers rely heavily on UV-928 to protect bumpers, side mirrors, and exterior trim made from PP and TPO (thermoplastic polyolefin). These components are constantly exposed to harsh sunlight, road debris, and temperature fluctuations.

A study conducted by BASF (2018) found that incorporating UV-928 at 0.5% concentration significantly reduced color fading and surface cracking in black-pigmented PP bumpers after 1,000 hours of xenon arc weathering tests.

🚗 Without UV-928, a car bumper might start looking like it aged ten years in one summer.

Case Study 2: Agricultural Films and Greenhouse Covers

Polyethylene films used in agriculture are prone to rapid degradation due to prolonged UV exposure. Adding UV-928 extends their service life from months to years.

According to a Chinese agricultural research institute (Zhang et al., 2020), PE films containing 0.3% UV-928 retained 85% of their original tensile strength after 18 months of field exposure, compared to just 40% for untreated films.

🌱 In short, UV-928 helps keep crops protected — and farmers smiling.

Case Study 3: Outdoor Consumer Goods

From garden furniture to children’s toys, many consumer products spend their lives outdoors. UV-928 ensures that these items remain durable, colorful, and safe for use.

An independent test by SGS (2021) showed that ABS toy parts with UV-928 maintained 95% of their initial impact strength after 500 hours of accelerated aging, while control samples lost over 60%.

🧸 Parents everywhere appreciate toys that don’t turn brittle or fade after a few summers.

Chapter 7: Best Practices for Using UV-928 in Injection Molding

Dosage Recommendations

The typical dosage of UV-928 ranges between 0.1% and 1.0% by weight, depending on the resin type and expected UV exposure level. Here’s a quick guide:

Resin Type	Recommended UV-928 Concentration (%)	Notes
Polypropylene	0.3 – 0.8	Ideal for automotive and outdoor parts
Polyethylene	0.2 – 0.6	Especially useful in agricultural films
ABS	0.5 – 1.0	High loading for maximum durability
Polycarbonate	0.2 – 0.5	Helps prevent yellowing
PVC	0.3 – 0.7	Often combined with HALS

⚖️ Too little UV-928 and your part is still vulnerable; too much and you risk blooming or increased costs.

Processing Tips

Uniform Dispersion: Ensure UV-928 is well dispersed in the polymer matrix. Masterbatch form is often preferred for better mixing.
Processing Temperature: UV-928 is stable up to 300°C, so no special precautions are needed during standard injection molding.
Compatibility Check: Always verify compatibility with other additives (e.g., flame retardants, pigments).
Storage: Store in a cool, dry place away from direct sunlight. Shelf life is typically 2–3 years if properly stored.

🧪 Think of UV-928 like seasoning — add it at the right time, mix it well, and you’ll get the best results.

Chapter 8: UV-928 vs. HALS – Friends or Foes?

You might have heard of HALS (Hindered Amine Light Stabilizers) being used alongside UV absorbers. So what’s the difference?

UV-928 stops UV radiation before it starts damaging the polymer.
HALS reverses or slows down the damage once it’s started.

Used together, they create a dual-defense system:

UV-928 blocks the incoming UV energy.
HALS scavenges free radicals formed during degradation, effectively “repairing” the damage in real-time.

📊 Synergy Score: ★★★★★

Many industry experts recommend combining UV-928 with a HALS such as Tinuvin 770 or Chimassorb 944 for optimal performance, especially in critical outdoor applications.

Chapter 9: Safety, Regulations, and Environmental Impact

Is UV-928 Safe?

Yes! UV-928 is classified as non-hazardous under current global standards. It complies with:

REACH Regulation (EU)
RoHS Directive
California Proposition 65
EPA Guidelines

It does not contain heavy metals, persistent organic pollutants (POPs), or substances of very high concern (SVHCs).

🌍 From an environmental perspective, UV-928 shows low aquatic toxicity and is not bioaccumulative. However, as with any chemical, proper handling and disposal practices should always be followed.

Chapter 10: Looking Ahead – The Future of UV Protection in Injection Molding

With increasing demand for sustainable materials and longer-lasting products, UV stabilizers like UV-928 are more important than ever.

Researchers are now exploring:

Nano-enhanced UV absorbers
Bio-based UV blockers
Self-healing polymers with built-in UV protection

But for now, UV-928 remains a trusted workhorse in the fight against UV degradation.

Conclusion: UV-928 – Small Molecule, Big Impact

In summary, UV-928 is a versatile, effective, and reliable UV absorber that plays a crucial role in extending the lifespan and maintaining the aesthetics of injection-molded plastic parts. Whether you’re manufacturing car bumpers, garden chairs, or medical devices, UV-928 provides a robust defense against the invisible enemy — ultraviolet radiation.

By understanding its properties, application methods, and compatibility with different polymers, you can ensure your products stand the test of time — and sunlight.

So next time you step outside, remember: your plastic parts need protection too. And with UV-928 on guard, they’ll be ready to face the sun head-on.

☀️🛡️

References

BASF SE. (2018). "Stabilization of Polyolefins: Performance Evaluation of UV-928 in Automotive Applications." Ludwigshafen, Germany.
Zhang, Y., Li, H., & Wang, X. (2020). "Effect of UV Absorbers on the Durability of Agricultural Polyethylene Films." Journal of Polymer Materials and Engineering, 37(2), 112–120.
SGS Product Testing Lab. (2021). "Accelerated Aging Tests on ABS Toys with UV-928 Additive." Geneva, Switzerland.
European Chemicals Agency (ECHA). (2022). "REACH Registration Dossier: UV-928." Helsinki, Finland.
American Chemistry Council. (2019). "Best Practices in UV Stabilization for Injection Molding." Washington, D.C.
Tang, J., Liu, M., & Chen, W. (2021). "Synergistic Effects of UV-928 and HALS in Thermoplastic Polyurethane." Polymer Degradation and Stability, 189, 109572.
ISO 4892-3:2013. "Plastics — Methods of Exposure to Laboratory Light Sources — Part 3: Fluorescent UV Lamps."
ASTM G154-20. "Standard Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials."

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