Analysis of the structure and main performance of the polarizer for LCD. Polarizer is one of the main raw materials of liquid crystal display (LCD), accounting for about 20%-30% of its manufacturing cost. However, since the manufacturing technology of polarizer has been monopolized by Japan, South Korea and other countries, the introduction of polarizer There is very little information. This article takes the polarizer for TN LCD as an example, and introduces some issues that many LCD polarizer users are more concerned about.
The structure of the polarizer
Polarizer is a kind of optical film with the function of generating polarized light, which is composited by multi-layer polymer materials. According to the different use positions of the liquid crystal screen, it can be roughly divided into surface sheet (also called transparent sheet) and negative film. Two types (also known as reflectors).
Materials and main functions of each layer
Polarizing layer: It is made of PVA (polyvinyl alcohol) film after dyeing and stretching. This layer is the main part of the polarizer, also known as the original polarizing film. The polarizing layer determines the polarization performance and transmittance of the polarizer, and it is also the main part that affects the color tone and optical durability of the polarizer. The basic processing technology of the polarizing layer can be divided into two series of dye series and iodine series according to the dyeing method. According to the stretching process, it can be divided into two series of dry stretching and wet stretching. Changing its material and processing technology can achieve the right Adjustment of polarization, transmittance, hue and optical durability. TAC layer: The polarizing layer made of PVA film is easy to absorb water, fade and lose its polarization performance. Therefore, it is necessary to use a TAC (triacetate cellulose ester) film with good optical uniformity and transparency on both sides to isolate moisture and air , Protect the polarizing layer. Using TAC film with UV CUT and Anti-Glare functions can be made into anti-ultraviolet polarizers and anti-glare polarizers.
Adhesive: It can be divided into reflective film side adhesive and peeling film side adhesive. The role of the reflective film side adhesive is to firmly bond the reflective film to the TAC film, and its process requirements do not allow re-peelability. The peeling film side adhesive is a pressure-sensitive adhesive, which determines the adhesion performance and patch processing performance of the polarizer. Its performance is one of the most concerned issues for LCD polarizer users. Separate film: It is a PET (ethylene terephthalate) film coated with a silicon coating on one side. It mainly protects the pressure-sensitive adhesive layer. At the same time, its peeling force is very important for the LCD patch. The workability has a certain impact.
Protective film: It is a PE (polyethylene) film coated with an EVA layer (ethylene vinyl acetate copolymer) on one side. It has low viscosity and protects the surface of the TAC film.
Reflective film (reflective film): It is a single-side PET film with aluminum vaporized. At present, most of the non-directional reflective vaporized aluminum film is used. If the reflective film is replaced with a transflective film, a transflective polarizer can be made. In addition, various gold-plated, silver-plated, and laser films can also be used as reflective films to obtain various background colors and mirrors. Reflection and other effects.
