紫外线吸收剂的机理
Mechanism of Ultraviolet Absorbent
1、紫外线吸收剂之所以能吸收紫外光是由于该类化合物分子中含有共轭π电子体系的结构与能够进行氢原子移动的结构两部分所致。也有的只有前一部分。
1. The reason why ultraviolet absorbers can absorb ultraviolet light is due to the structure of the conjugated pion electron system in the molecules of these compounds and the structure that can move hydrogen atoms. Others are just the first part.
2、紫外线吸收剂其结构分子中至少含有一个邻位羟基苯基取代基，这类化合物中由邻位羟基与氮原子或氧原子形成一螯合环，在吸收紫外线后，氢键断裂发生分子异构，分子内结构发生热振动，氢键破坏，螯合环打开，分子内结构发生变化，这样就将有害的紫外光变为无害的热能放出，从而保护了材料，
2. Ultraviolet absorbent contains at least one ortho-hydroxyphenyl substituent in its structural molecule. In these compounds, the ortho-hydroxyl group forms a chelating ring with nitrogen atom or oxygen atom. After absorbing ultraviolet rays, the hydrogen bond breaks and molecular isomerization occurs. Thermal vibration occurs in the structure of the molecule, the hydrogen bond breaks, the chelating ring opens and the structure of the molecule changes. The material is protected by the release of harmless heat energy.
3、在这个过程中，分子内所形成的螯合环是其具有吸收紫外线功能的关键，打开此环的能量敏感范围正好为290～400nm波长的紫外线能量范围。
3. In this process, the chelating ring formed within the molecule is the key to its ability to absorb ultraviolet radiation. The energy sensitive range of opening this ring is exactly the ultraviolet energy range of 290-400 nm.
4、另外，作为紫外线吸收剂，还必须能在紫外光或可见光的作用下不进行光化学反应；对化学药品 及水稳定性好，对热的稳定性好；挥发性小；对高分子材料的相容性好及不被溶剂萃取等。
4. In addition, as an ultraviolet absorbent, it must not undergo photochemical reaction under the action of ultraviolet or visible light; it has good stability to chemicals and water, good thermal stability; low volatility; good compatibility to macromolecule materials and no solvent extraction, etc.