阅读说明：本技术 一种光学膜、透明基板、图像显示装置以及太阳能电池 (Optical film, transparent substrate, image display device and solar cell ) 是由 李南文 许辉 于 2019-10-15 设计创作，主要内容包括：本发明提出了一种400nm光透射率达80％以上且线性热膨胀系数优异的光学膜；此外,本发明还提出了将该光学膜用于对透光性且线性热膨胀系数要求较高的制品和部件,例如透明基板、图像显示装置和太阳能电池。(The invention provides an optical film with 400nm light transmittance of more than 80% and excellent linear thermal expansion coefficient; further, the present invention proposes to use the optical film for products and parts requiring high light transmittance and a high linear thermal expansion coefficient, such as a transparent substrate, an image display device, and a solar cell.)

1. An optical film characterized by being a polyimide comprising a repeating structural unit,

wherein R1 is a residue obtained by removing 4 carboxyl groups from a tetracarboxylic dianhydride monomer containing an aromatic ring or an aliphatic ring; r2 is the residue of a diprimary amine monomer after removal of 2 amino groups; ar is a 2-valent organic group containing an aromatic ring.

2. The optical film according to claim 1,

r1 is at least one of the following groups:

r2 is the following group:

ar is the following group:

3. the optical film according to claim 1 or 2, wherein the polyimide further comprises a repeating structural unit,

wherein R3 is a residue obtained by removing 4 carboxyl groups from a tetracarboxylic dianhydride monomer which is the same as or different from R1; r4 is the residue of a primary diamine monomer which is the same as or different from R2 after removal of 2 amino groups.

4. The optical film according to claim 3,

r3 is at least one of the following groups:

r4 is at least one of the following groups:

5. the optical film according to any one of claims 1 to 4, wherein the linear thermal expansion coefficient of the optical film is 20ppm/K or less; further, the glass transition temperature is 300 ℃ or higher; more preferably, the optical film has a total light transmittance of 85% or more, and further, a transmittance of light having a wavelength of 400nm of 80% or more.

6. The optical film according to any one of claims 1 to 5, wherein the polyimide is obtained by synthesizing a polyamic acid from a tetracarboxylic dianhydride monomer and a primary diamine monomer, and then adding a dehydrating agent and an imidizing agent to the polyamic acid to perform imidization.

7. The optical film according to claim 6, wherein the optical film is obtained by imidizing the polyamic acid, adding the imidized polyamic acid to a poor solvent to precipitate a solid, dissolving the solid in an organic solvent, and coating the solution on a support to form a film; preferably, the poor solvent is at least one of methanol, ethanol, isopropanol (2-propanol), ethylene glycol, triethylene glycol and 2-butanol, and the organic solvent is at least one of an amide solvent, a ketone solvent and an ether solvent.

8. A transparent substrate made of the optical film according to any one of claims 1 to 8.

9. An image display device comprising the optical film according to any one of claims 1 to 8.

10. A solar cell comprising the optical film according to any one of claims 1 to 8.

Technical Field

The present invention relates to the field of optical materials, and in particular, to an optical film, a transparent substrate, an image display device, and a solar cell.

Background

Polyimide is a high polymer material, has excellent mechanical properties, thermal properties and electrical properties, is an important special high polymer material, and is applied to a plurality of fields such as machinery, electrical appliances, aerospace and the like. Different application fields have different requirements on the performance of the polyimide film, and in the application of flexible circuit boards, flexible solar cells, flexible display substrates and the like, the polyimide film material needs to have low thermal expansion coefficient, excellent dimensional stability and high heat resistance.

With the rapid development of optoelectronic technology, the field of optoelectronic devices has a development trend of intellectualization, light weight, ultra-thinning and flexibility in recent years, and the key to realizing the function is to obtain a transparent film material with light weight, flexibility and excellent comprehensive performance. The traditional glass substrate material cannot meet the requirement of the future flexible packaging technology due to the characteristics of hardness and brittleness. The polymer film material has the characteristics of light weight, flexibility, good transparency, excellent comprehensive performance and the like, can well meet the requirements of flexible optoelectronic device substrates, can adopt a roll-to-roll process to carry out large-scale and continuous production in the industrial processing process of the flexible transparent polymer substrates, and is beneficial to reducing the production cost. Therefore, the transparent polymer substrate material becomes the preferred material of the future flexible optoelectronic device.

In addition, when a fine element made of an inorganic material is formed on a film, the film after the formation of the inorganic element may be bent due to the difference in linear thermal expansion coefficient between the inorganic material and the film, and the inorganic element may be broken. Therefore, a film material having both transparency and heat resistance and having the same linear thermal expansion coefficient as that of the inorganic material is desired.

Polyimide is applied to electronic parts because of its heat resistance and high insulating property. Therefore, polyimide and a metal such as single crystal silicon or copper are often stacked, and attempts have been made to reduce the linear thermal expansion coefficient of polyimide to a level equivalent to that of single crystal silicon or metal.

Among these, polyimide having a fluorine substituent, for example, polyimide obtained from 2, 2' -bis (trifluoromethyl) diaminobiphenyl, is excellent in heat resistance and linear thermal expansion coefficient, and also relatively excellent in solubility in an organic solvent and transparency. However, no polyimide of this type has been disclosed so far as having excellent light transmittance for visible light.

Disclosure of Invention

Based on the technical problems existing in the background technology, the invention provides an optical film with 400nm light transmittance of more than 80% and excellent linear thermal expansion coefficient; further, the present invention proposes to use the optical film for products and parts requiring high light transmittance and a high linear thermal expansion coefficient, such as a transparent substrate, an image display device, and a solar cell.

The invention provides an optical film, which is polyimide containing the following repeated structural units,

wherein R1 is a residue obtained by removing 4 carboxyl groups from a tetracarboxylic dianhydride monomer containing an aromatic ring or an aliphatic ring; r2 is the residue of a diprimary amine monomer after removal of 2 amino groups; ar is a 2-valent organic group containing an aromatic ring.

Preferably, the first and second electrodes are formed of a metal,

r1 is at least one of the following groups:

r2 is the following group:

ar is the following group:

preferably, the polyimide further comprises a repeating structural unit,

wherein R3 is a residue obtained by removing 4 carboxyl groups from a tetracarboxylic dianhydride monomer which is the same as or different from R1; r4 is the residue of a primary diamine monomer which is the same as or different from R2 after removal of 2 amino groups.

Preferably, the first and second electrodes are formed of a metal,

r3 is at least one of the following groups:

r4 is at least one of the following groups:

preferably, the linear thermal expansion coefficient of the optical film is 20ppm/K or less; further, the glass transition temperature is 300 ℃ or higher; more preferably, the optical film has a total light transmittance of 85% or more, and further, a transmittance of light having a wavelength of 400nm of 80% or more.

Preferably, the polyimide is obtained by synthesizing polyamic acid from a tetracarboxylic dianhydride monomer and a primary diamine monomer, and then adding a dehydrating agent and an imidizing agent into the polyamic acid for imidization.

Preferably, the optical film is obtained by imidizing the polyamic acid, adding the imidized polyamic acid into a poor solvent to precipitate a solid, dissolving the solid into an organic solvent, and coating the organic solvent on a carrier to form a film; preferably, the poor solvent is at least one of methanol, ethanol, isopropanol (2-propanol), ethylene glycol, triethylene glycol and 2-butanol, and the organic solvent is at least one of an amide solvent, a ketone solvent and an ether solvent.

A transparent substrate is made of the optical film.

An image display device comprises the optical film.

A solar cell comprises the optical film.

According to the invention, through simultaneously introducing an amide group and an imide group into a polymer chain repeating structural unit of the polyimide optical film, the visible light transmittance of the polyimide obtained by the method is greatly enhanced; in actual operation, diamine containing an amide group can be used as a diamine primary amine monomer to participate in the reaction, and at the same time, fluorine atoms can be introduced into the molecular chain to further enhance the heat resistance of the polyimide, and finally an optical film excellent in transparency, heat resistance and linear thermal expansion coefficient is obtained. Further, the invention can also adopt a copolymerization method to introduce other polyimide structural units for blocking the close packing of macromolecular chains, thereby further improving the light transmittance and the thermal expansion of the optical film.

In addition, in the preparation of the optical film, in order to avoid film formation in the state of polyamic acid, the traditional method of thermally or chemically imidizing the film is abandoned, and a dehydrating agent and an imidizing agent are mixed in the polyamic acid to carry out imidization, so that the linear thermal expansion coefficient and the dimensional stability of the polyimide film are further improved.

The optical film of the present invention is excellent in transparency and heat resistance and has a low linear thermal expansion coefficient equivalent to that of various inorganic materials, and therefore is suitable as a film or a coating film for all members which are required to have known heat resistance and low expansibility (dimensional stability).

Drawings

FIG. 1 is a chart of the infrared spectrum of the optical film prepared in example 1;

FIG. 2 is a chart of the infrared spectrum of the optical film prepared in example 2;

FIG. 3 is a chart of the infrared spectrum of the optical film prepared in example 3;

Detailed Description

In the present invention, the proposed optical film is a polyimide comprising the following repeating structural unit,

wherein R1 is a residue obtained by removing 4 carboxyl groups from a tetracarboxylic dianhydride monomer containing an aromatic ring or an aliphatic ring; r2 is the residue of a diprimary amine monomer after removal of 2 amino groups; ar is a 2-valent organic group containing an aromatic ring.

The polyimide with the structural formula can be generated by adopting a tetracarboxylic dianhydride monomer and a diamine monomer structure containing an amido group, and the diamine monomer structure containing the amido group can be generated by adopting an aromatic dicarboxylic acid monomer and a primary diamine monomer structure;

wherein the monomer raw material of the tetracarboxylic dianhydride monomer structure can be 4, 4' - (hexafluoroisopropylidene) diphthalic anhydride, 4-oxydiphthalic anhydride, 1, 2, 3, 4-cyclobutane tetracarboxylic dianhydride, 1, 2, 4, 5-cyclopentane tetracarboxylic dianhydride, 2, 3, 5-tricarboxycyclopentane acetic dianhydride, 1, 2, 4, 5-cyclohexane tetracarboxylic dianhydride, bicyclo [2.2.1] hepta-2, 3, 5, 6-tetracarboxylic dianhydride, 3, 4, 6-tricarboxybicyclo [2.2.2] heptanyl acetic dianhydride, bicyclo [2.2.2] hepta-2, 3, 5, 6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3, 5, 6-tetracarboxylic dianhydride, decahydro-1, 4, 5, 8-dimethylene-2, 3, 6, 7-tetracarboxylic dianhydride or decahydrobiphenyl-3, 3', 4, 4' -tetracarboxylic dianhydride, but is not limited thereto;

the monomer raw material of the aromatic dicarboxylic acid monomer structure may be terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 2, 6-naphthalenedicarboxylic acid, 4 '-diphenyletherdicarboxylic acid, 4' -biphenyldicarboxylic acid, but is not limited thereto;

the monomer raw material of the diamine primary amine monomer structure may be 2, 2 '-bis (trifluoromethyl) -4, 4' -diaminobiphenyl, but is not limited thereto.

In the present invention, the proposed polyimide optical film contains the following repeating structural unit in addition to the repeating structural unit,

wherein R3 is a residue obtained by removing 4 carboxyl groups from a tetracarboxylic dianhydride monomer which is the same as or different from R1; r4 is the residue of a primary diamine monomer which is the same as or different from R2 after removal of 2 amino groups.

The polyimide with the structural formula can also be generated by adopting a tetracarboxylic dianhydride monomer structure and a diamine monomer structure;

wherein the monomer raw material of the tetracarboxylic dianhydride monomer structure can be pyromellitic dianhydride, 3', 4, 4' -biphenyltetracarboxylic dianhydride, 1, 2, 4, 5-cyclohexanetetracarboxylic dianhydride, 1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride, 4, 4-oxydiphthalic anhydride, 1, 2, 4, 5-cyclopentanetetracarboxylic dianhydride, 2, 3, 5-tricarboxycyclopentaneacetic acid dianhydride, bicyclo [2.2.1] hept-2, 3, 5, 6-tetracarboxylic dianhydride, 3, 4, 6-tricarboxybicyclo [2.2.2] heptanylacetic acid dianhydride, bicyclo [2.2.2] hept-2, 3, 5, 6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3, 5, 6-tetracarboxylic dianhydride, decahydro-1, 4, 5, 8-dimethylenenaphthalene-2, 3, 6, 7-tetracarboxylic dianhydride, decahydrobiphenyl-3, 3', 4, 4' -tetracarboxylic dianhydride, but is not limited thereto;

the monomer raw material for the diamine monomer structure may be 2, 4, 6-trimethyl-1, 3-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2' -bis (trifluoromethyl) -4, 4' -diaminobiphenyl, α ' -bis (4-aminophenyl) -1, 4-diisopropylbenzene, 4' -bis (2-trifluoromethyl-4-aminophenoxy) benzene, 3' -bis (2-trifluoromethyl-4-aminophenoxy) benzene, 4' -bis (2-methyl-4-aminophenoxy) benzene, 3' -bis (2-methyl-4-aminophenoxy) benzene, 4' -bis (2-trifluoromethyl-4-aminophenoxy) biphenyl, 4' -bis (2-methyl-4-aminophenoxy) biphenyl, 2' -bis (4-aminophenoxy) propane, 2' -bis (4-aminophenoxy) hexafluoropropane, 2' -bis (2-trifluoromethyl-4-aminophenoxy) propane, 2' -bis (4-aminophenoxy) diphenylsulfone, but is not limited thereto.

In the present invention, the optical film is produced by preparing the polyimide, and a polyamic acid can be obtained by a conventionally known method, and then imidized by adding a dehydrating agent and an imidizing agent to the polyamic acid, and then put into a poor solvent, thereby separating a polyimide solid.

For example, the reaction of the polyamic acid obtained from the tetracarboxylic dianhydride monomer and the amide group-containing diamine monomer can be carried out under conditions known from the past, and the order of addition or method of addition of the tetracarboxylic dianhydride and the diamine monomer is not particularly limited.

For example, in order to obtain the polyamic acid including the polyimide precursor of formula (1), the diamine monomer containing an amide group and/or other diamine monomer and tetracarboxylic dianhydride may be sequentially dissolved in an organic solvent and subjected to a polymerization reaction at an appropriate reaction temperature to obtain the polyamic acid including formula (1). Wherein the amount of the diamine monomer added is usually 1.0mol or more relative to 1mol of the tetracarboxylic dianhydride; the reaction temperature is not particularly limited as long as it is a temperature at which the reaction can proceed, and is usually 0 ℃ or higher, preferably 20 ℃ or higher; the reaction time is usually 1 hour or more, preferably 2 hours or more; the reaction environment may be air or an inert gas atmosphere; the organic solvent for the reaction is not particularly limited as long as it can dissolve the polyamic acid, and may be, for example, an amide solvent such as N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, or the like; as for the amide group-containing diamine monomer compound, it can be obtained by the conventionally known aminoacylation reaction as well.

Here, in obtaining the polyamic acid including both the structural formula (1) and the structural formula (2), the diamine monomer containing the amide group and the other diamine monomer and two different dianhydride monomers may be sequentially dissolved in an organic solvent in an equimolar ratio to be polymerized, thereby obtaining the polyamic acid including both the structural formula (1) and the structural formula (2). Wherein the amount of the diamine monomer containing an amide group is 50 mol% or more of the total amount of the diamine monomer.

In addition, when a polyimide resin is produced by imidizing the obtained polyamic acid, a dehydrating agent and an imidizing agent are added to the obtained polyamic acid to complete imidization, and then a poor solvent is added to the reaction solution to separate a polyimide solid.

For example, the following method can be used for separating the polyimide solid obtained: the polyimide resin can be precipitated in a solid state by adding a reaction solution containing polyimide, an imidizing agent and a dehydrating agent to a poor solvent, and the polyimide resin can be finally isolated. Wherein the dehydrating agent can be trifluoroacetic anhydride, acetic anhydride, propionic anhydride, aromatic monocarboxylic anhydride, acetyl chloride; as the imidizing agent, pyridine, p-pyrroline, lutidine, collidine, quinoline, isoquinoline, triethylamine, N-dimethylethanolamine; the poor solvent may be any poor solvent insoluble in the polyimide resin, or may be a mixture of the poor solvent and an organic solvent capable of dissolving the polyimide resin, and examples of the poor solvent include methanol, ethanol, isopropyl alcohol (2-propanol), ethylene glycol, triethylene glycol, and 2-butanol.

In the present invention, the optical film is produced by dissolving the polyimide solid obtained above in an organic solvent and then coating the solution on a support to form a film.

For example, the following methods can be specifically used: preparing polyimide into solution by using an organic solvent, uniformly coating the solution on a clean substrate by using a tape casting method, drying and peeling to obtain the optical film. The organic solvent used here may be an amide solvent such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone, a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone, or an ether solvent such as tetrahydrofuran, 1, 3-dioxolane, and 1, 4-dioxane, and these solvents may be used alone in 1 kind, or 2 or more kinds may be used in any ratio and in combination.

Hereinafter, the technical solution of the present invention will be described in detail by specific examples, but these examples should be explicitly proposed for illustration, but should not be construed as limiting the scope of the present invention.