Clear plastics
Low color for PC, PMMA and PET.
SUNSORB® 329
UV-329 Benzotriazole UV Absorber Supplier
SUNSORB® 329 (UV-329) is a benzotriazole UV absorber widely used in polycarbonate, polyester, PVC and acrylics. It combines strong UV absorption with low color in clear and light-colored parts.
CAS 3147-75-9 · Benzotriazole · UV absorber
- Lot COA with every shipment
- Samples for your trials
- Technical support for your trial
Product overview & key benefits
UV-329 (2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol) is a common choice for PC sheet, PET, PVC, PMMA and styrenics. It is also a frequent replacement for restricted benzotriazoles such as 327 and 328.
Broad compatibility
PC, polyester, PVC, styrenics and acrylics.
Replacement option
Common alternative to restricted 327 and 328.
Technical specifications
| Parameter | Typical value |
|---|---|
| Product Name | UV Absorber UV-329 |
| Brand | SUNSORB® 329 |
| CAS No. | 3147-75-9 |
| Chemical Name | 2-(2H-Benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol |
| Molecular Formula | C20H25N3O |
| Molecular Weight | 323.4 |
| Appearance | White to light-yellow powder |
| Melting Point | 103–105 °C |
| Assay | ≥99% |
| Volatile Matter | ≤0.5% |
| Ash | ≤0.1% |
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 329 is normally used and what to confirm before your trial.
Polycarbonate & Acrylics
UV protection for PC sheet and acrylic parts, typically 0.1–0.5%.
Check before trial
- Sheet or part thickness
- Clarity requirement
- Outdoor exposure
PET & Polyester
Protects polyester bottles, film and fiber.
Check before trial
- Polymer and process
- Processing temperature
- Color requirement
PVC & Styrenics
UV absorber for PVC and styrenic compounds.
Check before trial
- Compound type
- Exposure
- Existing stabilizers
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® 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® 360 | Bis-benzotriazole | 658.9 | ≥195 °C | PC, PET, PBT, thin parts | 0.1–0.5% |
| SUNSORB® 326 | Benzotriazole (Cl) | 315.8 | 138–141 °C | PP, PE, PVC, adhesives | 0.1–0.5% |
| SUNSORB® P | Benzotriazole | 225.2 | 128–132 °C | PS, PVC, PMMA, polyester | 0.1–0.5% |
*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
UV Absorber UV-329 FAQ
329 or 234 for polycarbonate?
Both are used. 234 has higher molecular weight and lower volatility for very high processing temperatures; 329 is a cost-effective standard.
Can 329 replace 328?
Often yes in plastics, depending on polymer and process. Re-run your weathering test after switching.
What dosage is typical?
0.1–0.5% depending on thickness and exposure.
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.
