WO2021042497A1

WO2021042497A1 - Polyimide precursor, polyimide film formed therefrom, and polyimide film preparation method

Info

Publication number: WO2021042497A1
Application number: PCT/CN2019/115884
Authority: WO
Inventors: 汪亚民
Original assignee: 武汉华星光电半导体显示技术有限公司
Priority date: 2019-09-03
Filing date: 2019-11-06
Publication date: 2021-03-11
Also published as: CN110643040A; CN110643040B

Abstract

Provided are a polyimide precursor, a polyimide film formed therefrom, and a method for preparing said polyimide. The polyimide precursor comprises a product formed from diamine and dianhydride; the diamine comprises a diamine containing a oxadiazole structure. The polyimide film formed from the polyimide precursor has high transmittance.

Description

Polyimide precursor, polyimide film formed therefrom, and preparation method of the polyimide film

Technical field

The present disclosure relates to a polyimide precursor, in particular to a polyimide film formed therefrom and a preparation method of the polyimide film.

Background technique

Polyimide (PI) occupies a very important role in the field of electronic materials. Its application fields mainly include auxiliary materials for assembly in integrated circuits, packaging materials, passivation layers of components and interlayer insulation materials, etc.; flexible printing The base material of the circuit board; bonding material, etc. In the field of Organic Light-Emitting Diode (OLED) panels, there is an increasing trend to use PI as its flexible substrate. However, traditional PI materials are brown or yellow, and have poor light transmission properties in the visible light band. This is mainly due to the strong conjugated structure in the molecule to form tight inter-chain stacking, which makes it easy for electrons to be transferred from diamine residues to Residues of dianhydride. Therefore, the current permeability of the PI substrate material is not high, which causes difficulty in the alignment of the bottom-emission OLED, which has become an important factor in the reduction of production yield. Therefore, how to provide PI flexible substrate materials with high optical transmittance in addition to maintaining mechanical strength and high heat resistance is an important issue in the field of electronic materials.

technical problem

The traditional PI material is brown or yellow, and has poor light transmission performance in the visible light band. This is mainly due to the strong conjugated structure in the molecule forming a tight inter-chain stacking, which makes it easy for electrons to be transferred from diamine residues to diamine residues. Anhydride residues. Therefore, the current permeability of the PI substrate material is not high, which causes difficulty in the alignment of the bottom-emission OLED, which has become an important factor in the reduction of production yield.

Technical solutions

In order to solve the above technical problems, an object of the present disclosure is to provide a polyimide precursor, a polyimide film formed therefrom, and a preparation method of the polyimide film to provide high heat resistance and high Polyimide film with optical transmittance is used as a flexible substrate material.

To achieve the above object, the present disclosure provides a polyimide precursor, which includes a product formed from a diamine and a dianhydride; wherein the diamine includes a diamine containing a dioxazole structure.

In one embodiment of the present disclosure, the dianhydride includes a fluorine-containing dianhydride.

In an embodiment of the present disclosure, the diamine and the dianhydride are mixed in a ratio of 1:1.2 mol to 1.5:2.5 mol.

In an embodiment of the present disclosure, the diamine containing a dioxazole structure is represented by the chemical formula (1):

In an embodiment of the present disclosure, the product formed by diamine and diacid anhydride includes the repeating unit represented by the chemical formula (2),

Wherein n is 20-100.

To achieve the above objective, the present disclosure additionally provides a polyimide film formed from the above polyimide precursor.

In an embodiment of the present disclosure, the polyimide film includes a repeating unit represented by the chemical formula (3),

Where n is 1000～2500.

To achieve the above objective, the present disclosure additionally provides a method for preparing a polyimide film, which includes the following steps:

S1: Dissolving the aforementioned polyimide precursor in a solvent to form a polyimide precursor solution;

S2: filtering the polyimide precursor solution and coating it on a substrate to form a film;

S3: The film is heated to remove the solvent and crosslink and cure it.

In an embodiment of the present disclosure, the S3 step further includes:

S4: Heat the film to remove at least 70% of the solvent;

S5: The film is heated at 120°C to 500°C to be crosslinked and cured.

In an embodiment of the present disclosure, before the step S2, the method further includes the step of heating the polyimide precursor solution at 50°C to 110°C.

Therefore, the present disclosure can provide a polyimide precursor and a polyimide film formed therefrom, wherein the polyimide precursor includes a product formed from a diamine and a dianhydride; the diamine includes A diamine containing a dioxazole structure, and the dianhydride includes a fluorine-containing dianhydride. Because the polyimide film formed by the polyimide precursor has a dioxazole structure, it can not only reduce the intermolecular force, but also destroy the close packing of the polymer and reduce its crystalline performance; plus the introduction of The dianhydride containing fluorine atoms, the fluorine atoms themselves have high electronegativity, which can effectively reduce the conjugation effect of polyimide molecules, thereby increasing the transmission of the polyimide film while maintaining heat resistance Sex.

Beneficial effect

Compared with the prior art, in order to solve the above technical problems, the present disclosure provides a polyimide precursor, a polyimide film formed therefrom, and a preparation method of the polyimide film. The polyimide film contains the dioxazole structure, which can not only reduce the intermolecular force, but also destroy the close packing of the polymer and reduce its crystalline performance; plus the introduction of dianhydride containing fluorine atoms, fluorine atoms It has high electronegativity and can effectively reduce the conjugation effect of polyimide molecules, thereby improving the permeability of the polyimide film while maintaining heat resistance.

Description of the drawings

FIG. 1 shows a schematic diagram of a curing process of a polyimide film according to an embodiment of the present disclosure;

FIG. 2 shows a graph of the thermal weight loss curve of a polyimide film according to an embodiment of the present disclosure; and

FIG. 3 shows a graph of light transmittance of a polyimide film according to one embodiment of the present disclosure.

The best mode of the present invention

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings of the specification, so as to fully introduce the technical content of the present invention to those skilled in the art, so as to demonstrate that the present invention can be implemented by examples, so that the technical content disclosed by the present invention is clearer and the present invention It is easier for those skilled in the art to understand how to implement the present invention. However, the present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text, and the description of the following embodiments is not intended to limit the scope of the present invention.

The terms "first", "second", "third", etc. (if any) in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and not necessarily used to describe a specific order Or precedence. It should be understood that the objects described in this way can be interchanged under appropriate circumstances.

The terms used in the specification of the present invention are only used to describe specific embodiments, and are not intended to show the concept of the present invention. Unless there is a clearly different meaning in the context, the expression used in the singular form encompasses the expression in the plural form. In the specification of the present invention, it should be understood that terms such as "including", "having", and "containing" are intended to indicate the possibility of the features, numbers, steps, actions, or combinations thereof disclosed in the specification of the present invention, but not The possibility that one or more other features, numbers, steps, actions or combinations thereof may exist or may be added is excluded.

The context has clear hints to the contrary, otherwise all the steps of the methods described in this article can be executed in any appropriate order. The changes of the present invention are not limited to the described sequence of steps. Unless otherwise claimed, any and all examples or exemplary language (for example, "for example") provided herein are only used to better illustrate the concept of the present invention, and not to limit the scope of the concept of the present invention. Without departing from the spirit and scope, those skilled in the art will easily understand various modifications and adaptations.

The present disclosure provides a polyimide precursor, which includes a product formed from a diamine and a diacid anhydride; wherein the diamine includes a diamine containing a dioxazole structure.

Preparation Example 1

Preparation Example 1 provides a preparation of a diamine containing a dioxazole structure as shown in the chemical formula (1).

Under a nitrogen atmosphere, add 0.9-1.5 mol of compound A dissolved in dichloromethane, add a dichloromethane solution of 0.8-1.6 mol of compound B at room temperature after stirring, and react for 3-12 hours. Stir thoroughly with anhydrous sodium sulfate and stand still, and then extract with ethanol to precipitate a white solid, which is then dried to obtain compound C.

In an argon atmosphere, add 0.05-5.6 mol of benzene p-borate, 0.02-6.9 mol of compound C, and 0.01-2.5 mol of potassium carbonate in a round bottom flask, and use dimethylformamide (DMF) The solvent is dissolved, stirring is continued for 2 hours, and then the temperature is raised to 40-70°C, 0.01-0.09 millimoles of tetrakistriphenylphosphonium palladium is added as a catalyst, and the temperature is increased to 80-100°C for 24 to 96 hours. Cool to room temperature, wash with deionized water to remove a large amount of water-soluble impurity ions, and then perform suction filtration and drying to obtain a dioxazole structure-containing diamine as shown in the chemical formula (1).

Preparation Example 2

Preparation Example 2 provides a preparation of a polyimide precursor. The polyimide precursor has a repeating unit represented by the chemical formula (2).

Wherein n is 20-100.

Add 1 to 1.5 moles of the dioxazole structure-containing diamine shown in the chemical formula (1) and 20 to 150 mL of N-methylpyrrolidone (NMP) into a round bottom flask under an argon atmosphere. After the amine is completely dissolved, 1.2-2.5 mol of fluorinated dianhydride monomer is added, and the polyimide precursor is obtained after continuous stirring at room temperature for 24 to 96 hours. The structural formula of the fluorinated dianhydride monomer is as follows:

Preparation Example 3

Preparation Example 3 provides a preparation of a polyimide film. The polyimide film has a repeating unit shown in the chemical formula (3),

Where n is 1000～2500.

The preparation method of the polyimide film includes the following steps:

S1: Dissolve the polyimide precursor obtained in Preparation Example 2 in a solvent to form a polyimide precursor solution;

S3: Heat the film to remove the solvent and make it crosslink and cure; wherein the S3 step further includes:

S4: Heat the film to remove at least 70% of the solvent;

S5: The film is heated at 120°C to 500°C to be crosslinked and cured.

Specifically, the polyimide precursor was added to 20 to 70 mL of NMP, heated to 50 to 110°C under an argon atmosphere, and reacted for 4 to 6 hours, and then cooled to 80°C to form a viscous solution. Use an organic filter membrane to filter to remove bubbles in the solution, suspend the obtained filtrate on a glass substrate, and then hold it at a constant temperature of 80°C for 0.5 to 1 hour in a vacuum environment to remove 70% of the NMP solvent, and then send it to a 450°C oven The film is cured and cross-linked to obtain the highly cross-linked polyimide film with high transmittance.

Further, the entire glass plate and the film are immersed in deionized water for 72 to 96 hours, the polyimide film is peeled, and the polyimide film is again dried in an oven at 80° C. to obtain a separated polyimide film.

FIG. 1 is a schematic diagram of a curing process of a polyimide film according to another embodiment of the present disclosure. Wherein, the crosslinking and curing process of the polyimide film is 3 to 5 hours; the heating rate is 4 to 10°C/min, and the maximum temperature is 420°C to 500°C. Heating is divided into two methods: hard drying and soft drying. Hard drying is to directly raise the temperature to the highest temperature and keep the temperature down for about 1h; soft drying is to divide the constant temperature platform for 2 times or more, and finally to cool down; the polyimide film Hard bake and soft bake to remove the solvent and cross-link and cure. However, the crosslinking and curing process of the polyimide film of the present disclosure is not limited to this.

Fig. 2 shows the thermal weight loss curve of the polyimide film according to one of the embodiments of the present disclosure. As shown in Fig. 2, it can be seen that the polyimide film of the present disclosure has a mass loss ≦1% at a temperature below 583.6°C Figure 3 shows the light transmittance curve of the polyimide film according to one of the embodiments of the present disclosure. As shown in Figure 3, the transmittance of the polyimide film of the present disclosure at a wavelength of 550nm or more is ≧80% ; It can be seen that the polyimide film of the present disclosure does have high heat resistance and high optical transmittance.

In summary, the present disclosure can provide a polyimide precursor and a polyimide film formed therefrom, wherein the polyimide precursor includes a product formed from diamine and dianhydride; The diamine includes a diamine containing a dioxazole structure, and the dianhydride includes a fluorine-containing dianhydride. Because the polyimide film formed by the polyimide precursor has a dioxazole structure, it can not only reduce the intermolecular force, but also destroy the close packing of the polymer and reduce its crystalline performance; plus the introduction of The dianhydride containing fluorine atoms, the fluorine atoms themselves have high electronegativity, which can effectively reduce the conjugation effect of polyimide molecules, thereby increasing the transmission of the polyimide film while maintaining heat resistance Sex.

The above are only preferred embodiments of the present disclosure. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present disclosure, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the present disclosure. protected range.

Claims

A polyimide precursor, characterized in that it comprises a product formed from a diamine and a diacid anhydride; wherein the diamine comprises a diamine containing a dioxazole structure.
The polyimide precursor of claim 1, wherein the dianhydride comprises a fluorine-containing dianhydride.
The polyimide precursor of claim 1, wherein the diamine and the dianhydride are mixed in a ratio of 1:1.2 mol to 1.5:2.5 mol.
The polyimide precursor of claim 1, wherein the diamine containing a dioxazole structure is represented by chemical formula (1):
The polyimide precursor of claim 1, wherein the product formed from diamine and dianhydride comprises a repeating unit represented by chemical formula (2),

Wherein n is 20-100.
3. The polyimide precursor of claim 2, wherein the diamine and the dianhydride are mixed in a ratio of 1:1.2 mol to 1.5:2.5 mol.
3. The polyimide precursor of claim 2, wherein the diamine containing a dioxazole structure is represented by the chemical formula (1):
3. The polyimide precursor of claim 2, wherein the product formed from diamine and dianhydride comprises a repeating unit represented by formula (2),

Wherein n is 20-100.
A polyimide film, characterized in that it is formed from the polyimide precursor according to claim 1.
9. The polyimide film of claim 9, wherein the dianhydride forming the polyimide precursor includes a fluorine-containing dianhydride.
9. The polyimide film of claim 9, wherein the diamine containing a dioxazole structure is represented by the chemical formula (1):
9. The polyimide film of claim 9, characterized in that it comprises a repeating unit represented by the chemical formula (3),

; Where n is 1000～2500.
A preparation method of polyimide film, characterized in that it comprises the following steps:

S1: Dissolving the polyimide precursor according to claim 1 in a solvent to form a polyimide precursor solution;

S2: filtering the polyimide precursor solution and coating it on a substrate to form a film;

S3: The film is heated to remove the solvent and crosslink and cure it.
The preparation method according to claim 13, wherein the step S3 further comprises:

S4: Heat the film to remove at least 70% of the solvent;

S5: The film is heated at 120°C to 500°C to be crosslinked and cured.
The preparation method according to claim 13, characterized in that, before step S2, it further comprises:

The step of heating the polyimide precursor solution at 50°C to 110°C.