Hindered Amine Light Stabilizers (HALS)

Hindered Amine Light Stabilizers (HALS) are chemical compounds used to protect polymers from degradation caused by ultraviolet (UV) light. These compounds are highly valuable because of their unique ability to absorb free radicals and prevent chain reactions that lead to polymer degradation.

Why do we need light stabilizers?

Polymers are susceptible to degradation under the influence of ultraviolet light. This degradation leads to discoloration, loss of strength, brittleness, and ultimately loss of the useful properties of the polymer. The use of light stabilizers is especially necessary in cases where polymers are exposed to direct sunlight.

How HALS Works

Instead of directly absorbing UV light, HALS works through a complex mechanism called the Denisov cycle. This cycle involves the following steps:

Free radical formation: When UV light is irradiated onto the polymer, free radicals are formed in it.

Free radical absorption by HALS: HALS molecules absorb these free radicals and form nitroxyl radicals.
HALS regeneration: Nitroxyl radicals gradually react with oxygen and are converted back into HALS molecules.

HALS Applications

HALS is used in various industries including packaging, automotive, construction, agriculture and electronics.
Packaging industry: Protection of plastic films, bottles and other packaging products from UV light.
Automotive industry: Protection of plastic parts of automobiles from degradation caused by sunlight.
Construction industry: Protection of paints, coatings and other polymeric materials from atmospheric agents.
Agricultural industry: Protection of greenhouse films and irrigation pipes.
Electronics industry: Protection of plastic parts in electronic equipment.