A Study on the Removal of Iodine and Boron Contents from Waste Polarizers

• Main Authors: Zhen-Huang Lai, 賴振煌
• Other Authors: Ming-Sheng Ko
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/6puabv

碩士 === 國立臺北科技大學 === 資源工程研究所 === 104 === Owing to the application of TFT-LCD increasing dramatically, the development of TFT-LCD industry is also growing rapidly in Taiwan. Polarizer, which is one of the important components of the TFT-LCD, mainly consists of PET protective film, pressure-sensitive adhesive (PSA), triacetate cellulose (TAC) or polyethylene terephthalate (PET), dyed polyvinyl alcohol film, and PET release film. Currently, the main manufacturing process of polarizer is that PVA soaks in iodine/potassium iodide aqueous solution to form complex film. Both LCD factory and waste LCD would produce a large amount of waste polarizer. The waste polarizer can be classified full-finished and half-finished polarizer. The difference between the full-finished polarizer and the half-finished polarizer is that the full-finished polarizer is combined with five layers and the half-finished polarizer is only combined with three layers. The common treatments of these waste polarizer are landfill or incineration at present. However, iodine and boron in PVA may cause secondary pollution during landfill or incineration. Therefore, the aim of this study was to study on the feasibility of removing iodine and boron from waste polarizers. The effect of the liquid-solid ratio, the concentration of soaking solution, the reaction time, the reaction temperature, the type of heating procedure, and the subsequent washing process on the removal efficiency of iodine and boron in PVA would be investigated. The results indicated that the optimum operation parameters were L/S ratio of 4, 5% NaOH, reaction temperature at 50℃ and reaction time in 120 minutes. The removal efficiency of iodine and boron achieved 61.3% and 54.2%, respectively. Moreover, the removal efficiency of iodine and boron in PVA would reach 93.2% and 100% after four stages of subsequent washing process. Therefore, the results indicated that the alkaline washing process was a feasible technique to remove boron and iodine from waste polarizers.