LG Chemical - PVA Separation of Polaroid Film Production


Polarizing films using iodine are widely used for liquid crystal displays, liquid crystal televisions, mobile phones, and PDAs because of their high transmittance and high polarization (high contrast). The main manufacturing processes are divided into five stages: TCA film processing, PVA film drawing, functional film coating, release film attachment, and aging & cutting.

During the PVA film drawing process, potassium iodide (KI) solution and boric acid are continuously discarded but there is a great need for concentration and reuse because of the limited nature of these raw materials. The figure below depicts how KI solution, boric acid, and PVA are separated after PVA film drawing process. Conventionally, PVA was removed by by cartridge filters but was insufficient because it had to be frequently replaced and had a PVA removal rate of less than 12%. FMX was considered for PVA removal process due to its high removal rate and durability. 

  <Figure 1. Potassium Iodine Reuse Method>

<Figure 1. Potassium Iodine Reuse Method>


FMX Performance:

BKT's FMX was able to improve upon PVA removal rate by more than 30% and is expected to increase total production yield by more than 5%. In addition, FMX's rotating blade technology suppressed fouling and facilitated stable operation without the need for replacing membrane frequently. 

  &lt;Figure 2. FMX and Cartridge Filter Comparison&gt;

<Figure 2. FMX and Cartridge Filter Comparison>


In 2017, LG Chemical purchased one FMX unit for their factory in South Korea. Satisfied with their results, LG Chemical put in an order for additional FMX units for their Nanjing factory in China. 

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