Tiangang® UV-234

What it is

Tiangang® UV-234 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: melting point 137 ~ 141.

Technical data

Chemical name	2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol
CAS number	70321-86-7
Structure
Molecular Weight	447.6 g/mol
Description	Tiangang® UV-234 is a highly effective UV absorber for polymers processed at high temperatures such as polycarbonate, polyesters, polyacetal, polyamides, polyphenylene sulfide, polyphenylene oxide, aromatic copolymers, thermoplastic polyurethane and polyurethane fibers, where loss of UVA is not tolerated. It protects organic polymers as well as pigments from UV light, improving and preserving the technical and visual performance of such applications. Tiangang® Tiangang® UV-234 features low volatility, exceptional light absorbing characteristics and good compatibility in various substrates. This makes the product especially suitable for applications characterized by high surface area, such as films and fiber.   Dosage level of Tiangang® UV-234 is between 0.10 and 0.60%, depending on substrate and performance requirements. When used in combination with Tiangang® series of Hindered Amine Light Stabilizers (HALS), synergistic performance is often observed.

Melting point 137 ~ 141 °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.

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-234: molecular weight and volatility, basicity, and compatibility with the other components in the system. High-MW benzotriazole with low volatility loss and high heat resistance for engineering plastics and hot processing.

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.

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