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SUNSORB® 328
UV-328 Benzotriazole UV Absorber Supplier
SUNSORB® 328 (UV-328) is a benzotriazole UV absorber used in coatings and plastics. UV-328 is listed under the Stockholm Convention and as a REACH SVHC, so its use is restricted in many markets; check your destination first.
CAS 25973-55-1 · Benzotriazole · UV absorber
- Lot COA with every shipment
- Samples for your trials
- Technical support for your trial
Product overview & key benefits
UV-328 (2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol) has been used in automotive coatings, PVC and polyolefins. It is now listed for elimination under the Stockholm Convention (with limited exemptions) and is a REACH SVHC. We supply it only where the destination allows, and help buyers move to alternatives such as 329, 234 or liquid 384-2 for coatings.
Replacement support
We propose and supply alternatives for restricted markets.
Coatings and plastics
Historically used in coatings, PVC and polyolefins.
Technical specifications
| Parameter | Typical value |
|---|---|
| Product Name | UV Absorber UV-328 |
| Brand | SUNSORB® 328 |
| CAS No. | 25973-55-1 |
| Chemical Name | 2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol |
| Molecular Formula | C22H29N3O |
| Molecular Weight | 351.5 |
| Appearance | Light-yellow powder |
| Melting Point | 80–83 °C |
| Assay | ≥99% |
Typical specification. Every shipment is supplied with a batch COA; the limits that apply to your order are confirmed in the quotation and contract.
Applications by Material
Pick an application to see how 328 is normally used and what to confirm before your trial.
Regulatory Status
Listed under the Stockholm Convention and REACH. Use depends on country and on specific exemptions.
Check before trial
- Destination country
- End use and any exemption claimed
- Customer specifications
Coatings Replacement
For coatings, liquid 384-2 or triazine 400 with a liquid HALS are common replacements.
Check before trial
- Coating type and binder
- Target durability
- Current 328 loading
Plastics Replacement
For plastics, 329 or 234 are common replacements depending on processing temperature.
Check before trial
- Polymer type
- Processing temperature
- Weathering test
Selection & comparison
Selecting a UV Absorber
| Your requirement | What usually works |
|---|---|
| Clear or light-colored polyolefin parts and film | Benzophenone (531) or benzotriazole (326) at low loading |
| High processing temperature (PC, PET, PA) | Low-volatility grades: 234, 360 or 1577-type triazines |
| Thin films and fibers | Higher-MW, low-volatility grades so the absorber is not lost in processing |
| Solvent-borne and waterborne coatings | Liquid benzotriazoles (384-2, 1130) or triazine (400), paired with a HALS |
| Outdoor service longer than one season | UV absorber plus a HALS; the absorber filters, the HALS stops radical chains |
| Exports to the EU | Check REACH status first; some benzotriazoles (327, 328) are restricted |
| Replacing an existing grade | Send your current TDS or COA; we match on chemistry and the parameters you approve |
UV Absorber Comparison
Swipe or scroll horizontally to see all columns →
| Product | Chemistry | Mol. weight | Melting point / form | Best fit | Typical starting level* |
|---|---|---|---|---|---|
| SUNSORB® 328 | Benzotriazole | 351.5 | 80–83 °C | Coatings, PVC (restricted markets) | 0.1–0.5% |
| SUNSORB® 329 | Benzotriazole | 323.4 | 103–105 °C | PC, PET, PVC, PMMA | 0.1–0.5% |
| SUNSORB® 234 | Benzotriazole | 447.6 | 137–141 °C | PC, PET, PA at high temperature | 0.1–0.5% |
| SUNSORB® 384-2 | Benzotriazole, liquid | — | Liquid | Coatings | 1–3% on binder solids |
| SUNSORB® 400 | Hydroxyphenyl-triazine, liquid | — | Liquid | Automotive and industrial coatings | 1–3% on binder solids |
*Starting points for trials, not fixed recommendations. Loading depends on part thickness, pigment, target service life and the HALS used alongside. UV absorbers and HALS work by different mechanisms and are usually combined.
Packaging & storage
Packaging
25 kg net bags or cartons with a PE inner liner. Palletized; private-label packing on request.
Storage
Keep sealed in a cool, dry, ventilated place away from heat and direct sun. See the SDS for full handling details.
Lead time & terms
Typically 3–15 business days from order confirmation, depending on quantity. FOB, CIF or DAP to major ports.
From first email to approved supply
Define the exposure
Indoor light behind glass, outdoor temperate climate and desert or tropical exposure need very different packages. Note the target service life and the weathering test you use (xenon or QUV, hours, ΔE or gloss retention).
Match absorber to process and thickness
A UV absorber works by filtering, so it needs enough path length: thick parts need less, thin films and fibers need more and need a low-volatility grade. Check the absorber survives your processing temperature.
Combine with a HALS
For outdoor use the standard approach is UV absorber plus HALS. Send your current package and pigment system and we suggest a starting combination for the trial.
Check regulations before you buy
Some benzotriazoles are restricted in the EU and other markets. Tell us the destination and end use, and we confirm the REACH and food-contact position of the grade before you order.
Tell us your requirement. We match the grade.
Start with your material, part thickness, quantity and destination. Add your current UV package and we will quote against it.
| Information | Example |
|---|---|
| Polymer / Material | PP, PE, ABS, compound, masterbatch |
| Application | Injection molding, extrusion, film, fiber |
| Current additive | Grade or supplier you use today |
| Required specification | Your TDS, COA or key limits |
| Quantity | Trial order / monthly / annual volume |
| Packaging | Standard 25 kg or specific requirement |
| Destination | Country and port |
| Documents needed | COA, SDS, REACH, food-contact statement |
Related products
SUNSORB® 400
Hydroxyphenyl-triazine liquid UV absorber for durable automotive and industrial coatings.
View product →UV Absorber UV-328 FAQ
Is UV-328 banned?
It is listed under the Stockholm Convention for elimination, with limited exemptions, and is a REACH SVHC. Rules differ by country, so tell us your market before ordering.
What replaces UV-328 in coatings?
Liquid benzotriazole 384-2 or hydroxyphenyl-triazine 400, combined with a liquid HALS such as 292, are common replacements.
What replaces UV-328 in plastics?
329 or 234, depending on polymer and processing temperature. Re-run your weathering test after switching.
Can I get a sample before ordering?
Yes. Tell us the polymer, the test you plan to run and the quantity you need. Samples ship with a COA so you can compare the lot against your current material.
What if a COA does not match our agreed specification?
Send us the agreed specification and the COA showing the difference (parameter, unit and test method). We check it with the production batch record before you accept the material, and replace or re-test where the lot is out of specification.
