Tiangang® AO-B225

What it is

Tiangang® AO-B225 is a antioxidant. Antioxidants come in two roles. Primary antioxidants (hindered phenols) trap radicals and stop the chain; secondary antioxidants (phosphites) decompose hydroperoxides. Used together they cover both processing and service life. Product identifiers: chemical name Mixture of tris (2,4-di-tert-butylphenyl)phosphite and tetra; CAS 31570-04-4.

Technical data

Chemical name	Mixture of tris (2,4-di-tert-butylphenyl)phosphite and tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane
CAS No.	31570-04-4 and 65447-77-0
Chemical structure
Main uses and properties	Tiangang® AO-B225 is a versatile blended antioxidant for polyolefins, engineering plastics and other polymer materials. It prevents thermo-oxidative ageing during processing and in long-term service, and extends the service life of the finished article. It can be used together with Tiangang® light stabilisers to extend outdoor service life. Tiangang® AO-B225 shows low blooming and good hydrolysis resistance, and effectively prevents the drop in melt index, discolouration and embrittlement caused by thermo-oxidative ageing, with better long-term thermal stability.

Where it is used, and at what loading

Polyolefins are the main field, followed by polyacetal, polyamide, polyester, PVC, polystyrene and elastomers. The higher the melt temperature and the longer the residence time, the more the system needs.

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 AO-B225: molecular weight and volatility, basicity, and compatibility with the other components in the system. Same 1010/168 family as B215 with a different ratio; choose on melt temperature and part life.

Frequently asked questions

Do primary and secondary antioxidants have to be used together?

In most cases yes. The primary handles radicals, the secondary handles hydroperoxides; using only one leaves the other degradation path open. Blends such as B215, B225 and B277 pre-mix the two, which removes weighing error at the line.

Why does low initial colour matter?

Some phenolic antioxidants form quinoid structures during processing and yellow the part. Fibre, film and light-coloured articles are most sensitive. Low-colour grades suppress that side reaction at the source.

Can antioxidants and light stabilizers interfere?

Yes, mainly through acid-base conflict. Acidic components (some phosphites, halogenated flame retardants) deactivate highly basic HALS. We look at both sides of the balance and switch to a low-basicity HALS where needed.

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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