PMP Pentamethylpiperidinol

What it is

Tiangang® PMP (1,2,2,6,6-Pentamethylpiperidin-4-ol) is a hindered amine intermediate. These are the raw materials or monomers used to build hindered amine light stabilizers. They are not end-use additives: the buyer still polymerises, esterifies or aminates them into finished grades such as 944, 622 or 2020. Product identifiers: chemical name 1,2,2,6,6-Pentamethylpiperidin-4-ol; CAS 2403-89-6; molecular weight 171.28.

Technical data

Molecular weight around 171 — low-MW territory: fast diffusion and early onset, at the cost of volatility and migration, which suits thin parts.

Where it is used, and at what loading

Downstream use concentrates on HALS synthesis; some grades also serve pharmaceuticals, agrochemicals, polymerisation inhibitors and epoxy curing. Specifications are usually tighter than for end additives, because purity, water and colour all carry into the next reaction step.

As a synthesis raw material it is charged by reaction stoichiometry, not by part loading.

Choosing between similar grades

Three things decide the choice for PMP: molecular weight and volatility, basicity, and compatibility with the other components in the system. N-methylated piperidinol carrying one extra methylation step, giving better basicity control and compatibility downstream — the input for Me-HALS.

Frequently asked questions

How much does intermediate purity affect downstream?

Directly. Impurities carry into the polymerisation and shift molecular-weight distribution and colour, which finally shows up as light-stabilising efficiency in the finished HALS. We control purity, water content and colour on these grades.

Why does one intermediate come in several specifications?

Because downstream processes differ. Polymerisation cares about monofunctional impurities, esterification about hydroxyl value, polymerisation inhibition about radical scavenging. The specification differences are downstream differences.

Can an intermediate be used directly as a light stabilizer?

A few can, where a low-MW piperidinol gives useful stabilisation in a specific system. Most cannot: the molecular weight is too low, so volatilisation and migration are too fast for long-service outdoor parts.

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.