Tiangang® UV-531

Uv absorber (uva) · UV-531

benzophenone type of UV absorber which imparts good light stability when used in combination with a Tiangang® HALS. It is compatible with most polyolefins, engineering plastics and PVC, and can be used to protect the polymer from degradation caused

In one sentence: A benzophenone UV absorber with molecular weight 326 and a 48 – 49 °C melting point, offering good compatibility at controlled cost.

  • Molecular weight: 326 g/mol (source: spec table on this page)
  • Melting range: 48 ~ 49 °C (source: spec table on this page)
  • Flash point: >200 °C (source: spec table on this page)
  • Transparent film and sheet dosage: 0.2 – 0.5% (source: recommended dosing table on this page)

What it is

Tiangang® UV-531 is a UV absorber (UVA). A UV absorber takes in 280–400 nm radiation and dissipates it as heat, acting as a filter layer at the surface. It does not scavenge radicals itself. Product identifiers: molecular weight 326; melting point 48 ~ 49.

Technical data

Chemical name2-Hydroxy-4-n-octoxybenzophenone
CAS number1843-05-6
StructureTechnical data
FormulaC21H26O3
DescriptionTiangang® UV-531 is a Benzophenone type of UV absorber which imparts good light stability when used in combination with a Tiangang® HALS. It is compatible with most polyolefins, engineering plastics and PVC, and can be used to protect the polymer from degradation caused by light exposure. It can be used in combination with antioxidants, phosphites, and light stabilizers. Recommended dosing level is 0.1~0.5% based on polymer weight.
AppearanceMolecular WeightMelting range
oC		Flash point
oC
Tiangang® UV-531Slightly yellow powder32648 ~ 49> 200
Tiangang® UV-531AcetoneChloroformEthanoln-HexaneMethanolTolueneWater
43> 503.5122> 50< 0.01
Tiangang® UV-531The use of proper protective equipment is recommended. Excess exposure to the product should be avoided. Wash thoroughly after handling. Store the product in a cool, dry, well-ventilated area away from incompatible materials.
Disclaimer
The information supplied is presented in good faith and has been derived from sources believed to be reliable. Since conditions of use are beyond our control, all risks are assumed by the user. No representation is expressed or implied, and nothing herein shall be construed as permission or recommendation to practice a patented invention without license.

Molecular weight around 326 — mid-range: a workable balance between diffusion speed and retention.Melting point 48 ~ 49 °C — the processing window needs to reach above it for uniform dispersion.

Where it is used, and at what loading

The difference from HALS is where it works: a UV absorber depends on its own absorption cross-section, so it is most visible in transparent film, coatings and sheet with a long optical path. In carbon-black or opaque systems its contribution is limited.

Transparent film and sheet0.2 – 0.5%
Moulded parts and profiles0.3 – 0.6%
Coatings (on dry film)1.0 – 3.0%

Figures above are typical industry ranges, not guaranteed values. The actual loading depends on wall thickness, design life and the other additives in the system, and should be established by a loading ladder on the real formulation.

Choosing between similar grades

Three things decide the choice for UV-531: molecular weight and volatility, basicity, and compatibility with the other components in the system. Grade 531 is the most cost-effective benzophenone, with absorption at shorter wavelengths; for stronger absorption and lower migration move to the benzotriazoles (326/327/328).

Frequently asked questions

Benzotriazole or benzophenone?

Benzophenones such as UV-531 are cost-effective and compatible but absorb at shorter wavelengths and migrate over time. Benzotriazoles (UV-326, 327, 328) absorb more strongly and resist migration, which is why engineering plastics mostly use them. Triazines (UV-570, UV-630) give the highest heat and weathering resistance for high-temperature processing and demanding outdoor parts.

Why pick a high-temperature grade for engineering plastics?

Engineering plastics are processed at 250–300 °C. A standard UV absorber volatilises or decomposes in that window, losing active content and contaminating the tool. High-temperature grades have a higher decomposition temperature and survive the process.

What should be watched when combining with HALS?

Acid-base interaction. Some UV absorbers and highly basic HALS interfere with each other in the same system and lose synergy. Our T-series packs are formulated with both sides of that balance in mind.

The figures and guidance above follow Tiangang's published technical material and common industry practice. For a specific formulation, refer to the batch COA and the technical agreement between the parties.

Technical reviewTiangang Technical CenterVersion2026-11-07
Specifications and application notes on this page are compiled from Tiangang's published technical data. Actual values are governed by the COA shipped with each lot and the technical agreement confirmed by both parties.

Certifications

  • National High-Tech Enterprise
  • Vice Chairman Unit, China Plastics Processing Industry Association (CPPIA)
  • Vice Chairman Unit, Agricultural Plastics Branch, China Agricultural Plastics Application Technology Society
  • Member, Ageing Methods Subcommittee, National Technical Committee on Plastics (SAC/TC15/CS5)
  • Member, Society of the Plastics Industry (SPI), USA

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