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Liquid crystal orientation agent as well as preparation method and application thereof

A liquid crystal aligning agent and solvent technology, used in liquid crystal materials, chemical instruments and methods, instruments, etc., can solve the problems of poor solubility of macromolecules, affect the uniformity of film thickness, and poor fluidity, and improve spray coating. Uniformity, the effect of improving product yield

Active Publication Date: 2022-05-06
长沙道尔顿电子材料有限公司
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  • Abstract
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  • Claims
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AI Technical Summary

Problems solved by technology

[0004] 1. When the viscosity of PI is high, the driving force in the spraying process of the sprayer is limited, and it is impossible to use a solution with too high viscosity for spraying operations
The viscosity specification of PI solution commonly used by spraying machines is 7-12cps. When using PI solution with a viscosity close to 12cps for operation, if the molecular weight distribution of PI is wide, the local viscosity of the polymer part will exceed the limit of 12cps, resulting in blockage of the nozzle
[0005] 2. When the solubility of PI is not good, macromolecules with higher molecular weight are prone to precipitate during storage, and tiny polymer gel particles that are difficult to observe with the naked eye will be produced in the solution. agglomeration, it will clog the nozzle and make the sprayer unable to operate normally
[0006] 3. When the molecular weight distribution of PI is wide, the fluidity of the part with high molecular weight is not good, and the film formed after spraying is thicker, while the film thickness of the part with low molecular weight is thinner, which seriously affects the uniformity of film thickness. There are even problems such as particles and bubbles
[0007] 4. When the PI solution is mixed with air bubbles, the nozzle will be blocked during the spraying process
Generally, the generation of air bubbles is reduced by adding a leveling agent to the PI system to reduce the surface tension of the solution, but commonly used leveling agents (such as diethylene glycol monobutyl ether and other ether alcohol solvents) are not good for PI. Solvent, if the PI molecular weight distribution is wide, the solubility of the macromolecular part is poor and easy to precipitate

Method used

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  • Liquid crystal orientation agent as well as preparation method and application thereof
  • Liquid crystal orientation agent as well as preparation method and application thereof
  • Liquid crystal orientation agent as well as preparation method and application thereof

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preparation example Construction

[0037] The invention provides a kind of preparation method of liquid crystal aligning agent, comprises the following steps:

[0038] (1) In a protective atmosphere, the diamine monomer, the acid anhydride and the solvent are mixed and subjected to a variable temperature reaction to obtain a polyamic acid solution;

[0039] (2) extracting, removing impurities and drying the polyamic acid solution in sequence to obtain a polyimide solid;

[0040] (3) In a protective atmosphere, the polyimide solid is dissolved and matured at high temperature in sequence to obtain the liquid crystal aligning agent.

[0041] In the present invention, the protective atmosphere in step (1) is preferably nitrogen, argon or helium.

[0042] In the present invention, the diamine monomer in the step (1) preferably includes p-phenylenediamine, 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl, 1,5-di- (3-aminophenyl)-1,5-dipentanone, 5-(3-octyl-cyclohexyloxy)-1,3-phenylenediamine and 4-(6-decyl-decalin- On...

Embodiment 1

[0073] (1) Prepare VA type polyamic acid liquid crystal aligning agent by temperature control method

[0074] In a nitrogen atmosphere, add 0.06 mol of DN-1, 0.03 mol of DN-2, 0.01 mol of DN-5 and 104.02 g of NMP, and control the speed at room temperature to be 240 rpm and stir for 30 min until the diamine monomers are completely dissolved, and then Add 0.05 mol of DA-1 and 0.05 mol of DA-2, control the temperature at 30°C, stir at 300rpm for 30min, then raise the temperature to 60°C, control at 300rpm and stir for 3.5h, and obtain a polyamic acid solution after the reaction; After diluting the polyamic acid solution with 319.49 g of NMP and 423.51 g of BC, it was filtered through a PP filter membrane with a pore size of 0.45 μm to obtain a transparent viscous polyamic acid solution.

Embodiment 2

[0076] (1) Prepare VA type polyamic acid liquid crystal aligning agent by traditional one-step method

[0077] In a nitrogen atmosphere, add 0.06 mol of DN-1, 0.03 mol of DN-2, 0.01 mol of DN-5 and 104.02 g of NMP, and control the speed at room temperature to be 240 rpm and stir for 30 min until the diamine monomers are completely dissolved, and then Add 0.05 mol of DA-1 and 0.05 mol of DA-2, control the temperature at 60 ° C, and stir at 300 rpm for 4 hours. After the reaction, a polyamic acid solution is obtained; the polyamic acid solution is mixed with 319.49 g of NMP and 423.51 g of After BC dilution, a transparent viscous polyamic acid solution was obtained.

[0078] (2) Polyamic acid aging treatment

[0079] In a nitrogen atmosphere, the diluted polyamic acid solution was aged at 80°C for 4 hours, and after the aging was completed, it was filtered with a PP material filter membrane with a pore size of 0.45 μm to obtain the finished product.

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Abstract

The invention belongs to the technical field of liquid crystal display elements. The invention provides a liquid crystal aligning agent, which avoids the defects caused by a one-step or two-step method. Diamine and dianhydride are mixed and then subjected to a variable-temperature reaction, the phenomenon that a high-activity monomer chain grows too fast due to system reaction heat release is reduced by controlling the initial reaction temperature, and the growth rate of the weight-average molecular weight is inhibited; then components with low molecular weight in the solution are separated in an extraction mode and are separated out into a solvent, so that the proportion of the components with low molecular weight is reduced; finally, the obtained solid is re-dissolved and subjected to high-temperature curing, active sites exist in macromolecular chains, high-molecular-weight macromolecules have more active sites, side reaction occurs in the curing process to cause chain scission, and therefore the weight-average molecular weight is reduced. By means of temperature control, extraction and curing, the spraying and coating uniformity of the orientation agent is obviously improved, the product yield is increased, and the method has practical value in the spraying and coating process.

Description

technical field [0001] The invention relates to the technical field of liquid crystal display elements, in particular to a liquid crystal aligning agent and a preparation method and application thereof. Background technique [0002] Polyimide (PI) has excellent properties such as extremely high thermal stability, good dielectric properties, corrosion resistance, and orientation stability, so it is widely used in liquid crystal aligning agents. [0003] With the upgrading of the production lines of LCD panel factories, the spraying method has become one of the mainstream PI coating methods. In the process of spraying, if the performance of PI fails to meet the spraying requirements, it is easy to cause various risks, which may lead to rework and affect production capacity, and may even reduce the service life of the equipment in severe cases. The PI material surface affects the spraying operation mainly in the following points: [0004] 1. When the viscosity of PI is high, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G73/10C09K19/56G02F1/1337
CPCC08G73/1028C08G73/1039C08G73/1042C08G73/1078C08G73/1085C09K19/542C09K19/56G02F1/133723
Inventor 苏江华王胜林黎厚明
Owner 长沙道尔顿电子材料有限公司
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