Polyolefin compatibility
The octyloxy chain gives good compatibility in PE and PP.
SUNSORB® 531
UV-531 Benzophenone UV Absorber Supplier
SUNSORB® 531 (UV-531) is a benzophenone UV absorber with good compatibility in polyolefins and PVC. It is a cost-effective, widely used choice for agricultural film, outdoor polyolefin parts and PVC.
CAS 1843-05-6 · Benzophenone · UV absorber
- Lot COA with every shipment
- Samples for your trials
- Technical support for your trial
Product overview & key benefits
UV-531 (2-hydroxy-4-n-octyloxybenzophenone) absorbs UV light in the 240–340 nm range and has good compatibility with PE, PP and PVC thanks to its octyloxy chain. It is often used with a HALS in agricultural and outdoor films.
Cost-effective
Widely used and economical for general outdoor protection.
Easy dispersion
Low melting point helps dispersion in compounding.
Technical specifications
| Parameter | Typical value |
|---|---|
| Product Name | UV Absorber UV-531 |
| Brand | SUNSORB® 531 |
| CAS No. | 1843-05-6 |
| Chemical Name | 2-Hydroxy-4-n-octyloxybenzophenone |
| Molecular Formula | C21H26O3 |
| Molecular Weight | 326.4 |
| Appearance | Light-yellow crystalline powder |
| Melting Point | 47–49 °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 531 is normally used and what to confirm before your trial.
PE Agricultural & Packaging Film
Used with a HALS in greenhouse and mulch film.
Check before trial
- Film thickness and target life
- Agrochemical exposure
- HALS used
Outdoor Polyolefin Parts
UV protection for PP and PE molded parts.
Check before trial
- Part thickness
- Pigment system
- Target weathering life
PVC
UV absorber for PVC profiles and sheets.
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® 531 | Benzophenone | 326.4 | 47–49 °C | PE, PP, PVC | 0.1–0.5% |
| SUNSORB® 326 | Benzotriazole (Cl) | 315.8 | 138–141 °C | PP, PE, PVC, adhesives | 0.1–0.5% |
| SUNLIGHT® 944 | Polymeric HALS | Mn 2000–3100 | Granule or powder | PP/PE film, tape, fiber | 0.1–0.6% |
| SUNLIGHT® 770 | Monomeric HALS | 480.7 | White powder or granule | Thick PP, PE, styrenics | 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-531 FAQ
531 or a benzotriazole?
531 is economical and compatible in polyolefins; benzotriazoles such as 326 give broader UV coverage. Many outdoor packages use either with a HALS.
What dosage is typical?
0.1–0.5% in most polyolefin applications, higher in thin film. Confirm in your weathering test.
Should I add a HALS?
For outdoor use, yes. The UV absorber filters light; the HALS stops the radical chain reactions.
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.
