Light Stabilizers: Knowledge about HALS

Light stabilizers are additives used to enhance the light aging resistance of polymer materials. Among them, HALS light stabilizers are widely recognized and applied due to their excellent resistance to light degradation. This article introduces common types of light stabilizers in the market, explores their mechanisms of action, and provides recommendations for selecting the appropriate stabilizers.

TINTOLL's light stabilizers are mainly divided into two categories: PowerSorb UV absorbers and PowerStab HALS. PowerSorb UV absorbers work by absorbing ultraviolet light and converting it into heat energy, reducing the damage caused by light energy to polymers, thus achieving light aging resistance. On the other hand, PowerStab HALS occupies an important position in the light stabilizer field due to its unique mechanism of action.

Mechanism of PowerStab Light Stabilizers

PowerStab HALS suppresses the light aging process of polymers through several mechanisms. Firstly, it can decompose hydroperoxides (ROOH) and convert them into harmless substances. Secondly, PowerStab HALS has a strong free radical trapping ability, which can neutralize and stabilize free radicals, preventing free radical-induced polymer chain scission reactions. Additionally, PowerStab HALS possesses regenerative capabilities, meaning it can restore its stability after capturing free radicals, thus maintaining its effectiveness over time. The nitrogen oxide free radicals generated by HALS and their reaction with broken chain free radicals are considered the core mechanism of its action. This reaction effectively interrupts the polymer chain scission process, significantly improving the polymer's light aging resistance.

Selection Standards

When choosing TINTOLL light stabilizers, the following standards should be considered:

For thin products (such as agricultural films): It is recommended to choose high molecular weight light stabilizers, such as PowerStab 944. High molecular weight stabilizers can disperse better within the polymer matrix, providing more durable light stability and effectively slowing down the aging process of agricultural films.

For thick products (such as coatings): It is recommended to choose low molecular weight light stabilizers, such as PowerStab 292. Low molecular weight stabilizers can penetrate more easily into the polymer, providing more comprehensive light stability and effectively preventing the aging reactions of coatings under ultraviolet light exposure.

Additionally, when selecting light stabilizers, the pH of the polymer system should be considered. Different polymer materials have varying sensitivities to pH, so it is important to select the appropriate light stabilizer based on the specific pH conditions of the system to ensure the maximization of light stability. It is recommended to make adjustments and conduct tests based on the specific polymer system and pH conditions to achieve the best light stability performance.