PI oriented film properties

PI-oriented film is composed of:
The heat curable polymer PI, PI alignment film component of the stock solution is a polyimide and DMA, NMP solvent and BC.
The UV-curable polymer PI, PI alignment film component of the stock solution with UV-active group is a polyimide and a solvent,128x64 oled such as PI liquid crystal orientation direction is the direction of radiation, so there soon productivity and convenience of operation , but because it is often insufficient polymerization, the current use of products make it into a single point defects in the display when a higher rate applies only to convert some of the light curtain's productions, rarely used on the LCD display, the following are no longer Description.
PI-oriented characteristics of the film:
Directing film with a PI LCD solids content in the stock solution is a small molecule compound, which is generated at a high temperature polymerization reaction to form with many branched long chain macromolecular solid polymer polyamides. Polymer molecules are branched chain and the main chain of the angle is called a pretilt angle guide layer. These polymers are branched chain group and the liquid crystal molecules between the relatively strong force, the liquid crystal molecules have the role of anchor,lcd module the pretilt angle of the liquid crystal can press direction.
PI not complete the polymerization liquid or a polyimide is a small molecule binding with the water molecules was sol, it will inhibit the polymerization of polyimide, not complete the main chain, branched-chain and have lost the original arrangement direction, lack of the required pre-tilt LCD production. So PI dope to moisture, humidity operating environment should be strictly controlled.
Some special STN and TFT PI, the cured in branched form on the basis of sub-branched, branched and branched times even the angle between the liquid crystal molecules coincide end structure or similar, so the liquid crystal have a more a strong anchoring effect. Thanks to the second branched-chain, such as if the liquid crystal molecules to increase the contact area between the guide layer, to a certain extent compensates for some of the guide layer processing defects. The PI in a large area display allows display more evenly. While avoiding rubbing treatment process in order to obtain high strength friction lower density higher friction, damage is relatively fragile and TFT generator CF layer.
Have been cured of the PI-oriented film can easily absorb moisture, and will break down in the water. And after rubbing treatment, the PI layer is likewise more fragile, prolonged exposure to the air, with the air in the water and carbon dioxide, thereby disrupting the original state of a branched arrangement, so that the pretilt angle is uneven, and even produce pretilt collapse phenomenon.
PI classification:
PI size at the pretilt angle is divided into:
1 to 3 degrees of low pretilt angle of the TN type PI and 4 to a high pretilt angle of 9 ° STN type PI.
PI affect the main parameters of the performance-oriented film
Solid content; viscosity; Na ion content; thermal decomposition temperature; permittivity; volume resistivity; transmission; absorption; refractive index; pretilt angle