紫外线吸收剂是塑料制品中非常重要的添加剂，是一种起光稳定作用的稳定剂，其主要是借吸收和转化太阳光中具有破坏性的紫外光部分而产生稳定效果。紫外线吸收剂主要应用于塑料制品中，如板材、线缆、管材等厚制品，在很多情况下，塑料薄膜中也会加入紫外线吸收剂，以抑制或延缓紫外光对被防护物品或物质的负面作用。

UV absorber is a very important additive in plastic products. It is a stabilizer for the stabilization of light. It is mainly a stabilizing effect by absorbing and transforming the ultraviolet light part of the sun light. UV absorbers are mainly used in plastic products, such as plates, cables, pipes and other thick products. In many cases, UV absorbers will also be added to plastic film to suppress or delay the negative effects of ultraviolet light on the protected objects or substances.

紫外线及其对塑料等聚合物的破坏作用

Ultraviolet radiation and its destructive effect on polymers such as plastics

我们都知道，从太阳发射出来的辐射线，其电磁波是非常宽的，能够到达地面的主要包括紫外线、可见光和红外线等。辐射线的能量与波长成反比，波长越短，能量越大。其中290nm-400nm波长范围内的紫外线，波长最短，能量也最高，其对塑料等聚合物的破坏性也最大，有机聚合物的键能通常在290~400kJ/mol范围内，故很容易为紫外线所破坏。因此，紫外线是影响塑料光老化的主要因素。但要注意的是不同结构的高分子化合物对紫外线各种不同长短波段的敏感程度是不一样的。

As we all know, the radiation from the sun is very wide, and it can reach the ground mainly including ultraviolet, visible and infrared light. The energy of the radiation line is inversely proportional to the wavelength, and the shorter the wavelength, the greater the energy. In the 290nm-400nm wavelength range, ultraviolet light has the shortest wavelength and the highest energy. It is also the most destructive to the polymers such as plastics. The bond energy of organic polymers is usually within the range of 290~400kJ/mol, so it is easily destroyed by ultraviolet. Therefore, ultraviolet radiation is the main factor affecting the photoaging of plastics. But it should be noted that different structures of polymer compounds are different in sensitivity to ultraviolet light.

塑料等高分子材料之所以具有许多优良性能，归结于其具有足够长的大分子链，但由于紫外线波长短、能量高，在紫外线作用（大多数还有氧的参与）下，高分子材料吸收紫外线后，容易形成电子激发态，这种激发态的分子可以引起一系列的光化学反应，即自由基链式反应，并同时与氧化相伴发生“光氧老化”或“光氧化反应”。高分子大分子链被切断或产生一定的交联，直接影响到了高分子材料的性能，于是就出现了一系列老化现象。如颜色变深、发脆、变硬、表面龟裂以及机械性能与电性能下降等，以致最后丧失其使用价值。

Polymer materials, such as plastics, have many excellent properties, due to their long chain of large molecules, but because of the UV wave length, high energy and ultraviolet radiation (most of the oxygen involved), the absorption of ultraviolet light by polymer materials is easy to form the excited state of the electron, which can be excited by the molecule. In order to cause a series of photochemical reactions, that is, free radical chain reaction, and at the same time with oxidation, "photooxidative aging" or "photooxidation reaction" occurs. Polymer macromolecule chain was cut off or produced a certain cross-linking, which directly affected the properties of polymer materials, so a series of aging phenomena appeared. Such as color darker, crisp, hardened, cracked surface and mechanical properties and electrical properties, and so on, and ultimately lose its use value.