KR100362433B1 - Polyimide precursor solution - Google Patents

Abstract

PURPOSE: Provided is a polyimide precursor solution which comprises a plasticizer for imparting the flexibility to the polyimide precursor solution, weakening an intermolecular force and thus facilitating the motion of molecular chain, and which can reinforce the adhesion of the polyimide. CONSTITUTION: The polyimide precursor solution comprising 65-95 parts by weight of N-methyl pyrroline, 5-35 parts by weight of polyamic acid, 0-15 parts by weight of n-butyl cellosolve, and 0-20 parts by weight of ethyl cellosolve, is characterized by further comprising 0.1-5.0 parts by weight of plasticizer. The plasticizer is selected from the group consisting of dibutylphthalate, n-dioctyl phthalate. The amount of plasticizer is 3 wt%. The solution further comprises a surfactant.

Description

Polyimide precursor solution

[Industrial use]

The present invention relates to a polyimide precursor solution, and more particularly, to a polyimide precursor solution capable of enhancing adhesion to polyimide by adding a plasticizer to a polyimide resin used as a liquid crystal alignment layer. will be.

[Private Technology]

A liquid crystal cell is a component of a liquid crystal display device composed of two glass substrates and liquid crystal is injected therebetween, and a transparent electrode constituting a pixel inside the two glass substrates. ) And a liquid crystal alignment film for orienting liquid crystal molecules in one direction thereon. However, it is difficult to obtain an optical effect through the molecular arrangement of the liquid crystal molecules only by injecting a liquid crystal material between two substrates assembled up and down, so that the liquid crystal display has an ordered arrangement state of the liquid crystal molecules in order to exhibit a specific optical effect. For this purpose, a process of forming an alignment film during the manufacturing process and an alignment film treatment process for performing a specific treatment are required.

As a specific method of substrate processing which makes a liquid crystal molecule have a constant orientation state with respect to the surface of a glass substrate, there exist a vertical alignment method and a horizontal alignment method.

Vertical alignment methods include vapor deposition such as SiOx, application of a surfactant such as a silane coupling agent, and the like. As the horizontal alignment method, a silicon oxide (SiO ₂ ) gradient deposition method, a polymer film rubbing method, a Langmuir-blodgett method and the like are known. Among them, the gradient deposition method of silicon oxide is a method of depositing silicon oxide on the surface of the glass at a very inclined angle, and the rubbing method is usually applied after a thin coating of an alignment material, which is a long chain polymer. The surface of the membrane is mechanically rubbed in a single direction using a soft material such as cloth, and the Langmore-Blughett method is a liquid level adsorbed to the air / water interface that is applied by using a barrier. The monomolecular film of a phase (usually water) is conveyed and accumulate | stored on the solid support one by one by the mechanical method in the state holding the state, and accumulating.

Among the above methods, liquid crystal aligning agents mainly used in the rubbing method include polyvinyl alcohol (PVA), silane, polyimide, and the like. Among them, it is superior to other organic polymer materials in consideration of orientation control ability, rubbing property, printability, chemical stability, etc., and in solubility of polyamic acid, it is easy to adjust concentration and viscosity. Polyimide having the characteristic of forming a stable polyimide film by curing is most widely used. Since the polyimide resin film has been developed, the rubbing method has been used in most liquid crystal display technologies.

In general, polyamic acid is synthesized by reacting a diamine compound and an acid anhydride in a solvent. Conventional polyimide precursor solutions include N-methylpyrroline (NMP), a solvent, and co-solvents n-butylcellosolve, ethylcelloslove, and co-solvent to increase coating properties. It is composed of polyamic acid, a polyimide precursor polymer, and the polyimide precursor solution is applied on two substrates and dried, followed by drying at 180 to 270 ° C. In the case of a typical aromatic polyamic acid, about 100 to 350 ° C, particularly completely In order to imidate, it imidized by dehydration reaction in the hardening furnace of 300-350 degreeC, the polyimide was formed and the alignment film of the liquid crystal cell was formed.

As described above, after forming the alignment layer with polyimide, the two substrates (for example, two glasses) must be contacted and adhered to each other, and then bonded. To do this, only the solvent remains or the glass transition temperature of the polymer is low and soft. do.

However, the above-described conventional polyimide precursor solution composed of N-methylpyrroline, a co-solvent for increasing the coating property, and a polyamic acid, which is a polyimide precursor polymer as a base resin, can be used to prepare two substrates. Before adhesion, all solvents are removed, resulting in poor adhesion. A proper amount of solvent must remain evenly on the entire surface to maintain proper adhesion. If only a conventional polyimide precursor solution is used as an alignment layer, the adhesion of polyimide It is weak and there is a problem in that it is not fully adhered to the two substrates, or only part is bonded. In addition, when the drying temperature rises to 80 ° C. or more in order to heat the polyimide precursor solution to form a polyimide, there is also a problem that there is no adhesive force of the polyimide.

[Problems to Solve Invention]

The present invention has been made to solve the problems of the prior art as described above, the object of the present invention is to provide flexibility to the polyimide precursor solution, weaken the intermolecular force to facilitate the movement of the molecular chain and to improve the glass transition. By adding a plasticizer that can be changed, it prevents the polyimide precursor film from being easily broken and at the same time ensures sufficient adhesive strength. After polyamide acid, which is a polyimide precursor, forms a film, even after the solvent has evaporated, the softness is maintained. When heat is applied in this state, the amide and the acid react to easily form imides. It is to lower the temperature.

[Means for solving the problem]

In order to achieve the object of the present invention as described above, the present invention comprises 65 to 95 parts by weight of N-methylpyrroline, 5 to 35 parts by weight of polyamic acid, 0 to 15 parts by weight of n-butyl cellosolve and ethyl cell The polyimide precursor solution which contains 0.1-5.0 weight part of plasticizers in the polyimide precursor solution containing 0-20 weight part of solves is provided.

EXAMPLE

Representative polyimide precursor solutions according to the present invention are as follows.

Plasticizer in a polyimide precursor solution containing 65 to 95 parts by weight of N-methylpyrroline, 5 to 35 parts by weight of polyamic acid, 0 to 15 parts by weight of n-butyl cellosolve, and 0 to 20 parts by weight of ethyl cellosolve It provides a polyimide precursor solution comprising 0.1 to 5.0 parts by weight.

In the present invention, it is possible to give flexibility to the polyimide precursor solution, dibutylphthalate, n-di as a plasticizer that can weaken the intermolecular force to facilitate the movement of the molecular chain and change the glass transition It is selected from the group consisting of octylphthalate, and in particular, 3 parts by weight of dioctylphthalate is most preferred as a plasticizer.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples and comparative examples are only preferred embodiments of the present invention for the purpose of better understanding of the present invention, and the present invention is not limited to the following examples.

(Example 1)

65 to 95 parts by weight of N-methylpyrroline, 5 to 35 parts by weight of polyamic acid, 0 to 15 parts by weight of n-butyl cellosolve, 0 to 20 parts by weight of ethyl cellosolve, 3 parts by weight of dioctylphthalate and an interface The active agent was mixed to prepare a polyimide precursor solution.

[effect]

As described above, the polyimide precursor mixture solution of the present invention maintains a soft property even after the polyamide acid as the polyimide precursor film is formed and the solvent evaporates, and the adhesion of the polyimide is enhanced to form two liquid crystal cells. After forming the alignment film between the glass substrate and can be completely adhered to the glass, it is possible to reduce the defective rate when manufacturing the liquid crystal cell, the amide and acid reacts to easily form the imide to lower the imidization temperature, In order to form the alignment layer, even if the drying temperature is increased to 80 ° C. or more, there is an advantage in that the adhesive force is not lost.

Claims (5)

In a polyimide precursor solution comprising 65 to 95 parts by weight of N-methylpyrroline, 5 to 35 parts by weight of polyamic acid, 0 to 15 parts by weight of n-butyl cellosolve, and 0 to 20 parts by weight of ethyl cellosolve, A polyimide precursor solution further comprising 0.1 to 5.0 parts by weight of a plasticizer. The polyimide precursor solution of claim 1 wherein the plasticizer is selected from the group consisting of dibutylphthalate, n-dioctylphthalate. The polyimide precursor mixture liquid according to claim 2, wherein the plasticizer is dioctylphthalate. The polyimide precursor solution according to claim 1, wherein the proportion of the plasticizer is 3 parts by weight. The polyimide precursor solution of claim 1 wherein the solution further comprises a surfactant.