1. Light shielding agent: This is a kind of material that can shield or reflect ultraviolet rays, so that light
can not penetrate into the polymer, thus can protect the polymer. Light shielding agents include inorganic
pigments such as carbon black, titanium oxide and organic pigments such as phthalocyanine blue and
phthalocyanine green, among them carbon black has the best shielding effect.
2.Ultraviolet absorbent: It can effectively absorb ultraviolet radiation with wavelength of 290-410 nm, but
rarely absorb visible light. It has good thermal stability and light stability. According to its chemical structure,
it can be divided into o-hydroxybenzophenones, benzotriazoles, salicylates, triazines and substituted
acrylonitriles. It can be used as auxiliary light stabilizer and hindered light stabilizer, especially in polyolefins
3. Quenching agent: It can accept the energy absorbed by the chromophore in plastics and disperse the
energy in the form of heat, fluorescence or phosphorescence, thus protecting the polymer from ultraviolet
damage. It has good stabilization effect on polymers and is mostly used in thin films and fibers. It is mainly
some divalent organic nickel chelates. Organic nickel light stabilizers have good properties, but due to
the toxicity of heavy metal ions, they may be replaced by other non-toxic or low toxic quenchers.
4.Free radical scavengers: These light stabilizers can capture the active free radicals generated in
polymers, thus inhibiting the photooxidation process and achieving the goal of light stabilization. Mainly
hindered amine light stabilizer (HALS). It is the most promising new type of high-efficiency light stabilize
r with an average annual growth rate of 20%-30% in the world.
5. Hydroperoxide decomposer: one of the hindered amine light stabilizers. Hydroperoxide can be produced
during storage and processing, which leads to photooxidation degradation of polymers. Hydroperoxide
decomposer can decompose peroxides, generate stable nitrogen-oxygen free radicals, and further capture
free radicals, thus inhibiting polymer degradation.