Tiangang® HS-765

What it is

Tiangang® HS-765 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: molecular weight 508;

Technical data

Chemical name	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-765 is a highly effective liquid radical scavengers belonging to the Hindered Amine Light Stabilizer family of light stabilizers, well suited for use in a wide range of polymers to improve weatherability in applications including polyurethanes, sealants, adhesives, elastomers, unsaturated polyesters, acrylics, vinyl polymers (PVB, PVC), styrene homo- and copolymers, polyolefins, liquid color concentrates, and other organic substrates. It has low volatility and high thermal stability. Its liquid form makes it easy for handling and incorporation. It has synergistic effect when used with a UV absorbent.

Molecular weight around 508 — mid-range: a workable balance between diffusion speed and retention.

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-765: molecular weight and volatility, basicity, and compatibility with the other components in the system. Low-basicity route for acidic systems such as sulfur pesticides and halogenated flame retardants. Lower MW than 625, so it diffuses faster — good for thin parts.

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 (HS-950, HS-362, BW-10LD) 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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