Polymeric HALS UV Stabilizer (High MW, Low Volatility)
Key Features
- Very low migration and volatility — remains active in composite matrix throughout service life
- Designed for 15–25 year outdoor service life applications in infrastructure and marine
- Same HALS radical scavenging efficiency as monomeric HALS with far superior retention
- Effective in backing laminates where UV protection persists after gelcoat ablation
- Preferred for solar, infrastructure, and structural composites with long-life UV requirements
Polymeric HALS UV Stabilizer is a high-molecular-weight, oligomeric hindered amine light stabilizer designed for applications requiring maximum long-term weathering protection, minimum migration, and retention in the composite or coating matrix over service lifetimes of 15–25 years or more. Unlike monomeric HALS (Tinuvin 770 type, MW ~481), polymeric HALS (MW 2000–4000) has very low volatility and migration due to its large molecular size, making it strongly retained in the polymer network throughout the service life of outdoor composites.
The polymeric HALS radical scavenging mechanism is identical to monomeric types — nitroxide radicals catalytically trap photooxidation-generated carbon-centered radicals, preventing chain scission and discoloration. The benefit of polymeric HALS is persistence: monomeric HALS can gradually evaporate or be leached from composite surfaces, especially in water-immersed or warm outdoor applications over many years. Polymeric HALS remains in the matrix far longer, providing sustained protection that is critical for 20+ year outdoor applications such as infrastructure composites, marine structural parts, and solar energy system components.
Polymeric HALS is particularly recommended for application in gelcoat backing laminates, thick structural composite layers, and applications where surface ablation or wear removes the outer gelcoat over time — the HALS present in backing layers provides continued protection as the surface is consumed. It is used at 0.5–1.5 phr, typically in combination with liquid benzotriazole UVA for the most demanding outdoor weathering applications.
Specifications
| Parameter | Value |
|---|---|
| Appearance | Pale yellow to amber liquid or soft solid |
| CAS Number | 65447-77-0 |
| Amine content | ~1.5–2.0 mmol N/g |
| Chemical type | Oligomeric/polymeric hindered amine (piperidine-based) |
| Typical loading | 0.5–1.5 phr |
| Molecular weight | 2000–4000 g/mol |
| Migration resistance | Very low (high MW) |
Applications
FAQ
Monomeric HALS (Tinuvin 770 type, MW ~481) is mobile in the polymer matrix. Over time, especially in warm and humid outdoor environments, it can migrate to the surface and evaporate (estimated 10–30% loss over 10 years in outdoor gelcoat). Polymeric HALS (MW 2000–4000) is physically trapped in the matrix due to its large size — it cannot migrate to the surface and evaporate at a significant rate. The reduced extraction also means the HALS remains active throughout the design life of the composite structure, rather than being depleted in the first 5–10 years. For infrastructure composites rated for 25+ years, polymeric HALS is the standard specification.
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