三醋酸纤维素酯薄膜的荧光紫外老化特性研究

Research on Aging Characteristics of Cellulose Triacetate Film under Ultraviolet Fluorescent Lamp

液晶显示器在户外使用时,遇到长时间的太阳光照射,会降低液晶显示器显示效果和寿命。偏光片表层的三醋酸纤维素酯(TAC)薄膜,在设计过程中加入紫外吸收剂阻隔紫外线,保护液晶分子、偏光素子晶体结构以及TAC膜,避免紫外线照射后受到破坏。该文采用不同的紫外老化条件,包括氙灯、荧光紫外灯UVA-340、荧光紫外灯UVB-313等对偏光片进行了紫外老化测试,分析了偏光片的老化特性。探讨了荧光紫外灯UVB-313光照、冷凝紫外老化测试TAC出现“白霜”不良现象的机理原因。结果表明,发生“白霜”不良现象是因为TAC膜中三醋酸纤维素酯在UVB-313光照下发生断裂,形成小分子纤维素酯,在水的作用下TAC加速水解并析出表面。在TAC膜中加大紫外吸收剂含量可增强阻隔紫外线的效果,200~380 nm透过率小于0.1%,可以提升TAC的抗UV性能,避免TAC在紫外线照射下发生分子键断裂问题,提高产品品质。

When the liquid crystal display is used outdoors,it will be exposed to the sun for a long time,which will reduce the display effect and life of the liquid crystal display,and even fail and affect the display effect.For the TAC on the surface of the polarizer,the UV absorber is added during the design process to block UV light,protect the liquid crystal molecules,the polarized photonic crystal structure and the TACfilm to avoid bond cleavage of damaged molecules after being irradiated by UV light.In this paper,the ultraviolet aging test of polarizer is carried out by using different ultraviolet aging test conditions,including xenon lamp test,ultravioletfluorescent lamp UVA-340,ultravioletfluorescent lamp UVB-313,etc.,and the aging characteristics of polarizer are analyzed.The mechanism and reason of the poor phenomenon of"white frost"in TAC under UVfluorescent lamp UVB-313 illumination and condensation aging test were discussed.The results show that the poor phenomenon of"white frost"is that the TACfilm breaks under UVB-313 light,forming small molecular cellulose ester,which accelerates the hydrolysis reaction and precipitates to the surface under the action of water.Adding more ultraviolet absorber to the TACfilm to block ultraviolet rays,the transmittance at 200~380 nm is less than 0.1%,which can improve the anti-UV performance of TAC,avoid molecular bond breakage in TAC,and effectively improve product quality.