Tiangang® HS-508

What it is

Tiangang® HS-508 is a hindered amine light stabilizer (HALS). HALS trap the radicals formed when a polymer photo-oxidises and regenerate in the process, so the protection window is longer than that of a UV absorber, which is consumed as it works. Product identifiers: chemical name 癸二酸双(1,2,2,6,6-五甲基-4-哌啶)酯与1-(甲基)-8- (1,2,2,6,6-五甲基-4-哌啶)癸二酸酯; CAS 41556-26-7.

Technical data

Chemical name	Mixture of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and methyl(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate
CAS number	41556-26-7  / 82919-37-7
Structure
Description	Tiangang® HS-508 is a highly effective radical scavenger belonging to the Hindered Amine Light Stabilizers (HALS) family of stabilizers. It is a liquid HALS that displays outstanding light stabilities in applications, like coatings, printing ink, and polyurethane lacquer, preventing the surface from blowing-out or peeling-off. It is widely used for light stability in polypropylene, polyethylene, styrenics, unsaturated polyester, acrylics, vinyl polymers (PVC, PVB), including plastisols, elastomers, adhesives, sealants and coatings. In particular, it is often recommended for polyurethanes because of its solubility in polyols. Tiangang® HS-508 (292) typically demonstrates reduced interaction with co-additives such as pigments or other stabilizers. Tiangang® HS-508 (292) has strong synergy effect with UV absorbent of benzotriazo family, particularly when used in coatings for automotives and wooden furniture.

Where it is used, and at what loading

Suitable for polyolefins (PP, PE), polyurethane, polyamide, polyacetal and polyester. Thin and thick parts call for different grades: thin sections suffer from volatilisation and migration, thick sections from surface bloom.

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 HS-508: molecular weight and volatility, basicity, and compatibility with the other components in the system. Liquid grade 292 for coatings and thin films: solid HALS disperse poorly in coatings, liquid does not, and it meters easily.

Frequently asked questions

Is this grade meant for thin or thick parts?

It depends on molecular weight and migration tendency. Low-MW grades diffuse quickly and act early but volatilise and migrate over time; high-MW grades (944, 622, 950 series) suit long-service outdoor parts. Tiangang offers both, so the choice follows wall thickness and design life.

Is it worth combining with a UV absorber?

Yes, they cover different stages. The UV absorber shields incoming UV energy; the HALS scavenges radicals that have already formed. Agricultural film, automotive exterior and PV backsheet usually need both to reach their design life.

What happens if the loading is too high?

Beyond the compatibility limit the additive blooms to the surface, which wastes material and harms appearance and print adhesion. Protection also stops scaling linearly. Our practice is a loading ladder on the actual system, then fix the cost-performance knee.

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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