废弃液晶面板中液晶材料的热解特性

作为废弃液晶面板的重要组成部分,液晶材料中含有芳环、氰基、氟、氯、溴等基团,若随意丢弃或采用不当的处置方式将严重污染环境。本研究拟利用热解处理技术实现对液晶材料的无害化处理,探究了废旧薄膜晶体管液晶显示器中液晶材料的热解特性。液晶材料的热重分析结果表明,液晶材料的主要热解温度为300～500?C;热解实验表明,热解温度对液晶材料热解产物的影响较大,其中300?C和500?C条件下主要生成了双环己烷类、联苯类等化合物,而在800?C条件下主要生成多环芳烃;此外,考察了热解温度、氮气流量及固相停留时间对液晶去除率的影响,在优化条件下液晶的去除率可达94.2%。本研究为废旧液晶面板中液晶材料的无害化处理提供了技术参数和理论参考。

Study on Pyrolysis Characteristics of Liquid Crystal Materials from Waste Liquid Crystal Display Panels

As a significant component of liquid crystal display panels, liquid crystal materials contain substituent groups as aromatic ring, cyano group, fluorine, chlorine, bromine, and the improper disposal could cause serious environmental problems. In this research, pyrolysis process was used to remove the liquid crystal materials from waste liquid crystal display. Pyrolysis characteristics of waste thin film transistor liquid crystal display panels are studied. Thermogravimetric analysis results show that liquid crystal mainly pyrolyzed from 300-500 oC. Meanwhile, it can be conducted from the pyrolysis process that the temperature has a significant influence on the pyrolysis products. At 300 oC and 500 oC, the main products are organic compounds with bicyclohexyl, biphenyl, etc. However, polycyclic aromatic hydrocarbons were generated at 800 oC. Furthermore, effects of pyrolysis temperature, nitrogen flow rate as well as solid resident time on liquid crystal removal rate were conducted in this study. The liquid crystal removal rate can reach 94.2% under the optimum condition. This study provides technical parameters and theoretical foundation for the non-hazardous treatment of waste liquid crystal display panels.