1. Light shielding agent: This is a type of substance that can block or reflect ultraviolet rays, preventing light from penetrating into the polymer, thus protecting the polymer. Light shielding agents include inorganic pigments such as carbon black and titanium oxide, and organic pigments such as phthalocyanine blue and phthalocyanine green. Among them, carbon black has the best shielding effect.
2. Ultraviolet absorber: It can effectively absorb ultraviolet rays with a wavelength of 290 to 410nm, while rarely absorbing visible light. It has good thermal stability and light stability. According to their chemical structure, they can be mainly divided into: o-hydroxybenzophenones, benzotriazoles, salicylates, triazines, and substituted acrylonitriles. Used as an auxiliary light stabilizer and hindered light stabilizer, especially in polyolefins or coatings.
3. Quencher: It can accept the energy absorbed by the chromophore in the plastic and dissipate this energy in the form of heat, fluorescence or phosphorescence, thus protecting the polymer from ultraviolet damage. It has a good stabilizing effect on polymers and is mostly used in films and fibers. Mainly some divalent organic nickel chelates. Organic nickel light stabilizers have good performance, but due to the toxicity of heavy metal ions, they may be replaced by other non-toxic or low-toxic quenchers.
4. Free radical capture agent: This type of light stabilizer can capture active free radicals generated in polymers, thereby inhibiting the photooxidation process and achieving light stabilization. Mainly hindered amine light stabilizers (HALS). It is the most promising new type of high-efficiency light stabilizer, with an average annual demand growth rate of 20% to 30% internationally.
5. Hydroperoxide decomposer: It is one of the hindered amine light stabilizers. Polymers can produce hydroperoxides during storage and processing, leading to photooxidative degradation of polymers. Hydroperoxide decomposers can decompose peroxides to generate stable nitrogen-oxygen free radicals and further capture free radicals. , thereby inhibiting polymer degradation.
