Light stabilizer is an additive for polymer products (such as plastics, rubber, coatings, synthetic fibers).
It can shield or absorb the energy of ultraviolet rays, quench singlet oxygen and decompose hydroperoxide
into inactive substances, It can make polymer Under the light irradiation, the light chemical reaction possibility
can be eliminated or slowed down, and the process of light oxygen can be prevented or delayed, so can
prolong the service life of polymer products.
Damage effect of ultraviolet radiation on polymers
Solar light is a kind of electromagnetic wave. When it passes through space and ozone layer, the radiation
below 290 nm and above 3000 nm are almost filtered out. The actual electromagnetic wave reaching the
ground is 290-3000 nm. Among them, visible light is in the range of 400-800 nm (about 40%), infrared light
is in the range of 800-3000 nm (about 55%) and wave is in the range of 400-800 nm (about 40%). Ultraviolet
radiation is about 290-400 nm long (only 5%).
Ultraviolet radiation in sunlight is the main reason for aging of polymer materials. Ultraviolet radiation accounts
for only about 5% of the sun's light, but it has a lot of energy. After absorbing ultraviolet rays, polymer products
can cause self-oxidation and degradation of polymer, destroy the chemical bonds of polymer, make it break
and cross-link, and lead to vicious changes in appearance and physical and mechanical properties of polymer
products, such as color, strength and life. This process is called Photoredox or photoaging.
Mechanism of Light Stabilizer
Light stabilizers have different functions because of their different structures and varieties. Some can shield,
reflect or absorb ultraviolet rays and convert them into harmless heat energy; others can quench the excited
states of molecules or groups stimulated by ultraviolet rays and make them return to the ground state,
eliminating or slowing down the possibility of Photoredox reaction; others can capture the free radicals
generated by photoredox, from It prevents the free radical reaction leading to the aging of the products and
protects the products from ultraviolet damage.