COMPOSITE FILM AND PREPARATION METHOD THEREOF

Abstract

The present invention provides a composite film and a preparation method thereof. The composite film includes polyimide and a dense silica layer formed on a surface of the polyimide.

Claims

1. A composite film, comprising a polyimide film and a dense silica layer formed on a surface of the polyimide film, wherein the dense silica layer has density ranging from 2 g/cm.sup.3 to 3 g/cm.sup.3, and a thickness ranging from 10 to 500 nm.

2. The composite film according to claim 1, wherein the composite film has a thickness ranging from 50 to 300 μm.

3. A composite film, comprising a base substrate and a dense silica layer formed on a surface of the base substrate.

4. The composite film according to claim 3, wherein the base substrate is a polyimide film, and the dense silica layer has density ranging from 2 g/cm.sup.3 to 3 g/cm.sup.3.

5. The composite film according to claim 3, wherein the composite film has a thickness ranging from 50 to 300 μm, and the dense silica layer has a thickness ranging from 10 to 500 nm.

6. A method of preparing a composite film, comprising the following steps: providing a support substrate; coating a composite solution on the support substrate, and baking the composite solution at a low temperature to remove an organic solvent thereof to obtain a thin film layer, wherein the composite solution comprises a solution of polyamic acid and a solution of polysiloxane; heating the thin film layer to cause imidization of the polyamic acid and hydrolysis of the polysiloxane to obtain a polyimide-silica composite film; and peeling off the support substrate to obtain the composite film.

7. The method according to claim 6, wherein a molar ratio of the polyamic acid solution to the polysiloxane solution in the composite solution is in a range of 1:0.1-0.2.

8. The method according to claim 6, wherein the polyamic acid solution is obtained by a polycondensation reaction of dianhydride and diamine at a low temperature in a first solvent, and a molar ratio of the dianhydride to the diamine is 1:0.95-1.05.

9. The method according to claim 7, wherein the dianhydride is at least one of pyromellitic dianhydride, cyclobutane tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, and pyromellitic phthalic anhydride, 4,4′-oxophthalic anhydride; and, the diamine is at least one of 4,4′-biphenyldiamine, 3,4′-diaminodiphenyl ether, and p-phenylenediamine.

10. The method according to claim 6, wherein the polysiloxane solution is obtained by a hydrolysis condensation reaction of alkoxysilane in a second solvent using a catalyst; and the alkoxysilane is at least one of trimethoxysilane, methyltriethoxysilane, and dimethyldioxysilane.

11. The method according to claim 6, wherein the first solvent is at least one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl, and sulfoxides; a second solvent is at least one of ethanol and polyethylene glycol; and the catalyst is ammonia water.

12. The method according to claim 6, wherein the composite solution coated on the support substrate is baked at a temperature of 20 to 80° C. to remove the organic solvent to obtain the thin film layer, and the imidization is carried out at a temperature of 350 to 550° C.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the embodiments or the technical solutions of the existing art, the drawings illustrating the embodiments or the existing art will be briefly described below. Obviously, the drawings in the following description merely illustrate some embodiments of the present invention. Other drawings may also be obtained by those skilled in the art according to these figures without paying creative work.

[0029] FIGS. 1A and 1B are schematic structural diagrams of a process for preparing a flexible substrate according to an embodiment of the present invention.

[0030] FIG. 2 is a schematic structural diagram of a display panel according to an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0031] With reference to the appended drawings, exemplary embodiments of the present invention will be described in detail below. To aid in understanding the present invention, like numbers refer to like elements throughout the description of the figures, and the description of the same elements will be not reiterated. For illustration clarity, many details of practice are explained in the following descriptions. However, it should be understood that these details of practice do not intend to limit the present disclosure.

[0032] The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.

[0033] In the present invention, the formation of a first feature over or under a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Moreover, the first feature “above”, “over” and “on” the second feature includes the first feature directly above and above the second feature, or merely indicating that the first feature is at a level higher than the second feature. The first feature “below”, “under” and “beneath” the second feature includes the first feature directly below and obliquely below the second feature, or merely the first feature has a level lower than the second feature.

[0034] The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, they are merely examples and are not intended to limit the invention. In addition, the present invention may be repeated with reference to the numerals and/or reference numerals in the various examples, for the purpose of simplicity and clarity, and do not indicate the relationship between the various embodiments and/or arrangements discussed. Moreover, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the use of other processes and/or the use of other materials.

Example 1. Preparation Method of a Composite Film

[0035] In this embodiment, a method for preparing a composite film is provided, including the following steps:

[0036] 1) Preparation of a Composite Solution

[0037] 1.1) Dianhydride and diamine are dissolved in a polar organic solvent in a molar ratio of 1:0.95-1.05, followed by polycondensation at a temperature of 10 to 40° C. to obtain a precursor of a polyamic acid (PAA) solution.

[0038] The dianhydride is at least one of pyromellitic dianhydride, cyclobutane tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, and pyromellitic phthalic anhydride, 4,4′-oxophthalic anhydride; the diamine is at least one of 4,4′-biphenyldiamine, 3,4′-diaminodiphenyl ether, and p-phenylenediamine; and the polar organic solvent is at least one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0039] 1.2) Alkoxysilane is dissolved in the polar organic solvent and ammonia water is added as a catalyst, and a sufficient hydrolysis condensation reaction is carried out at a temperature of 10 to 30° C. to obtain a polysiloxane (PSA) solution.

[0040] The alkoxysilane is at least one of methyltrimethoxysilane, methyltriethoxysilane, and dimethyldioxysilane; and the polar organic solvent is ethanol or polyethylene glycol.

[0041] 1.3) A polyamic acid solution and a polysiloxane solution are mixed in a molar ratio ranging from 1:0.1-0.2 to obtain a uniform composite solution of PAA-PSA.

[0042] 2) Film Formation at Low Temperature

[0043] The composite solution is applied to a support substrate to form a thickness of 50 to 300 μm under a nitrogen atmosphere, and then a film formation reaction is carried out at a temperature of 20 to 80° C. for 1 to 20 minutes to remove the solvent.

[0044] 3) Thermal Imidization Reaction

[0045] A thermal imidation reaction was carried out at a temperature of 350 to 550° C. for 0.1 to 1 hour under a nitrogen atmosphere; and then the film is cooled to room temperature to obtain the composite film.

[0046] In this embodiment, a method for preparing a composite film is specifically provided, including the following steps:

[0047] 1) Preparation of a Composite Solution

[0048] 1.1) Biphenyltetracarboxylic acid dimethyl anhydride and p-phenylenediamine are dissolved in N-methyl-2-pyrrolidone as a polar organic solvent in a molar ratio of 1:0.95, wherein a total amount of the biphenyltetracarboxylic acid dimethyl anhydride and the p-phenylenediamine is 100 parts by weight, and then a sufficient polycondensation reaction (5 hours) is carried out at a low temperature of 30° C. to obtain a precursor of a polyamic acid (PAA) solution.

[0049] 1.2) Methyltrimethoxysilane is dissolved in polyethylene glycol as the polar organic solvent, and ammonia water is added as a catalyst, and a sufficient hydrolysis condensation reaction (5 hours) is carried out at a temperature of 10° C. to obtain a polysiloxane (PSA) solution.

[0050] 1.3) The above polyamic acid solution and a polysiloxane solution are mixed in a molar ratio of 1:0.1 to obtain a uniform composite solution of PAA-PSA.

[0051] 2) Film Formation at Low Temperature

[0052] As shown in FIG. 1A, the above composite solution of PAA-PSA is uniformly coated on a clean and smooth support substrate in a high-purity nitrogen atmosphere, and a wet film having a thickness of 200 μm is baked at a temperature of 40° C. for 20 minutes to remove the polar organic solvent.

[0053] 3) Thermal Imidization Reaction

[0054] As shown in FIG. 1B, after raising the temperature to 450° C. at a rate of 5° C./min in a high-purity nitrogen atmosphere, the thermal imidization reaction is carried out for 1 hour, and the composite film 10 is obtained after cooling to room temperature.

[0055] In the thermal imidization reaction of the step 3), the polysiloxane in the uniform composite solution which forms the wet film decomposes due to an increase in temperature, and then transforms into silica having a regular network structure and gradually migrates to a surface of a polyimide film. Thus, as shown in FIG. 1B, the prepared composite 10 includes a polyimide film layer 11 and a uniform and dense silica layer 12 formed on a surface of the polyimide film layer 11. The uniform and dense silica layer 12 is found to have density of 2.13 g/cm.sup.3 and a thickness of 400 nm after an experimental test.

Example 2. Preparation Method of Composite Film A

[0056] In this embodiment, a method for preparing a composite film is specifically provided, including the following steps:

[0057] 1) Preparation of a Composite Solution

[0058] 1.1) Pyromellitic dianhydride and 4,4′-biphenyldiamine are dissolved in N-methyl-2-pyrrolidone as a polar organic solvent in a molar ratio of 1:0.95, wherein a total amount of the pyromellitic dianhydride and 4,4′-biphenyldiamine is 100 parts by weight, and then a sufficient polycondensation reaction (8 hours) is carried out at a low temperature of 20° C. to obtain a precursor of a polyamic acid (PAA) solution.

[0059] 1.2) Methyltrimethoxysilane is dissolved in polyethylene glycol as a polar organic solvent, and ammonia water is added as a catalyst, and then a sufficient hydrolysis condensation reaction (3 hours) is carried out at a temperature of 20° C. to obtain a polysiloxane (PSA) solution.

[0060] 1.3) The above polyamic acid solution and polysiloxane solution are mixed in a molar ratio of 1:0.15 to obtain a uniform composite solution of PAA-PSA.

[0061] 2) Film Formation at Low Temperature

[0062] Similar to Example 1, the above composite solution of PAA-PSA is uniformly coated on a clean and smooth support substrate in a high-purity nitrogen atmosphere, and the wet film having a thickness of 300 μm is baked at a temperature of 60° C. for 10 minutes to remove the polar organic solvent.

[0063] 3) Thermal Imidization Reaction

[0064] Similar to Example 1, after raising the temperature to 500° C. at a rate of 10° C./min in a high-purity nitrogen atmosphere, the thermal imidization reaction is carried out for 0.2 hours, and after the film is cooled to room temperature, the composite film A is obtained. The uniform and dense silica layer 12 in the composite film A was found to have a density of 2.8 g/cm.sup.3 and a thickness of 500 nm after an experimental test.

Example 3. Preparation Method of Composite Film B

[0065] In this embodiment, a method for preparing a composite film is specifically provided, including the following steps:

[0066] 1) Preparation of a Composite Solution

[0067] 1.1) Cyclobutane tetracarboxylic dianhydride and p-phenylenediamine are dissolved in N,N-dimethylformamide as a polar organic solvent in a molar ratio of 1:1, wherein a total amount of the cyclobutane tetracarboxylic dianhydride and p-phenylenediamine is 100 parts by weight, and a sufficient polycondensation reaction (2 hours) is then carried out at a low temperature of 40° C. to obtain a precursor of a polyamic acid (PAA) solution.

[0068] 1.2) Dimethyldioxysilane is dissolved in ethanol as a polar organic solvent, and ammonia water is added as a catalyst, and a sufficient hydrolysis condensation reaction (1 hour) is then carried out at a temperature of 30° C. to obtain a polysiloxane (PSA) solution;

[0069] 1.3) The above polyamic acid solution and polysiloxane solution are mixed in a molar ratio of 1:0.2 to obtain a uniform composite solution of PAA-PSA.

[0070] 2) Film Formation at Low Temperature

[0071] Similar to Example 1, the above composite solution of PAA-PSA is uniformly coated on a clean and smooth support substrate in a high-purity nitrogen atmosphere, and the wet film having a thickness of 50 μm is baked at a temperature of 20° C. for 20 minutes to remove the polar organic solvent.

[0072] 3) Thermal Imidization Reaction

[0073] Similarly to Example 1, after raising the temperature to 350° C. at a rate of 10° C./min in a high-purity nitrogen atmosphere, the thermal imidization reaction is carried out for 1 hour, and the composite film B is obtained after cooling to room temperature. The dense silica layer in the composite film B was found to have a density of 2.2 g/cm.sup.3 and a thickness of 20 nm after an experimental test.

Example 4. Preparation Method of Composite Film C

[0074] In this embodiment, a method for preparing a composite film is specifically provided, including the following steps:

[0075] 1) Preparation of a Composite Solution

[0076] 1.1) Benzophenone tetracarboxylic dianhydride and 3,4′-diaminodiphenyl ether are dissolved in N,N-dimethylformamide as a polar organic solvent in a molar ratio of 1:1.05, wherein a total amount of the benzophenone tetracarboxylic dianhydride and 3,4′-diaminodiphenyl ether is 100 parts by weight, and a sufficient polycondensation reaction (10 hours) is then carried out at a low temperature of 10° C. to obtain a precursor of a polyamic acid (PAA) solution.

[0077] 1.2) Dimethyldioxysilane in polyethylene glycol as a polar organic solvent, and ammonia water is added as a catalyst, and a sufficient hydrolysis condensation reaction (5 hours) is then carried out at a temperature of 10° C. to obtain a polysiloxane (PSA) solution;

[0078] 1.3) The above polyamic acid solution and polysiloxane solution are mixed in a molar ratio of 1:0.1 to obtain a uniform composite solution of PAA-PSA.

[0079] 2) Film Formation at Low Temperature

[0080] Similar to Example 1, the above composite solution of PAA-PSA is uniformly coated on a clean and smooth support substrate in a high-purity nitrogen atmosphere, and the wet film having a thickness of 250 μm is baked at a temperature of 40° C. for 10 minutes to remove the polar organic solvent.

[0081] 3) Thermal Imidization Reaction

[0082] Similarly to Example 1, after raising the temperature to 400° C. at a rate of 10° C./min in a high-purity nitrogen atmosphere, the thermal imidization reaction is carried out for 0.8 hours, and after the film is cooled to room temperature, the composite film C is obtained. The uniform and dense silica layer in the composite film C was found to have a density of 2.5 g/cm.sup.3 and a thickness of 150 nm after an experimental test.

Example 5. Preparation Method of Composite Film D

[0083] In this embodiment, a method for preparing a composite film is specifically provided, including the following steps:

[0084] 1) Preparation of a Composite Solution

[0085] 1.1) 4,4′-oxophthalic anhydride and 3,4′-diaminodiphenyl ether are dissolved in dimethyl sulfoxide as a polar organic solvent in a molar ratio of 1:1, wherein a total amount of the 4,4′-oxophthalic anhydride and 3,4′-diaminodiphenyl ether is 100 parts by weight, and a sufficient polycondensation reaction (10 hours) is then carried out at a low temperature of 10° C. to obtain a precursor of a polyamic acid (PAA) solution;

[0086] 1.2) Methyltriethoxysilane is dissolved in polyethylene glycol as a polar organic solvent, and ammonia water is added as a catalyst, and a sufficient hydrolysis condensation reaction (4 hours) is then carried out at a temperature of 25° C. to obtain a polysiloxane (PSA) solution;

[0087] 1.3) The above polyamic acid solution and polysiloxane solution are mixed in a molar ratio of 1:0.1 to obtain a uniform composite solution of PAA-PSA;

[0088] 2) Film Formation at Low Temperature

[0089] Similar to Example 1, the above composite solution of PAA-PSA is uniformly coated on a clean and smooth support substrate in a high-purity nitrogen atmosphere with a wet film thickness of 150 μm and baked at a temperature of 80° C. for 1 minute to remove the polar organic solvent;

[0090] 3) Thermal Imidization Reaction

[0091] Similarly to Example 1, after raising the temperature to 550° C. at a rate of 20° C./min in a high-purity nitrogen atmosphere, the thermal imidization reaction is carried out for 0.1 hour, and after the film is cooled to room temperature, the composite film D is obtained. The dense silica layer in the composite film D was found to have a density of 2.0 g/cm.sup.3 and a thickness of 10 nm after an experimental test.

Example 6. Preparation Method of Composite Film E

[0092] In this embodiment, a method for preparing a composite film is specifically provided, including the following steps:

[0093] 1) Preparation of a Composite Solution

[0094] 1.1) Biphenyltetracarboxylic acid dimethyl anhydride and p-phenylenediamine are dissolved in -methyl-2-pyrrolidone as a polar organic solvent in a molar ratio of 1:1.05, wherein a total amount of the biphenyltetracarboxylic acid dimethyl anhydride and the p-phenylenediamine is 100 parts by weight, and a sufficient polycondensation reaction (8 hours) is then carried out at a low temperature of 25° C. to obtain a precursor of a polyamic acid (PAA) solution.

[0095] 1.2) Methyltrimethoxysilane is dissolved in polyethylene glycol as a polar organic solvent, and ammonia water is added as a catalyst, and a sufficient hydrolysis condensation reaction (4 hours) is then carried out at a temperature of 25° C. to obtain a polysiloxane (PSA) solution;

[0096] 1.3) The above polyamic acid solution and polysiloxane solution are mixed in a molar ratio of 1:0.2 to obtain a uniform composite solution of PAA-PSA.

[0097] 2) Film Formation at Low Temperature

[0098] Similar to Example 1, the above composite solution of PAA-PSA is uniformly coated on a clean and smooth support substrate in a high-purity nitrogen atmosphere, and the wet film having a thickness of 100 μm is baked at a temperature of 30° C. for 7 minutes to remove the polar organic solvent.

[0099] 3) Thermal Imidization Reaction

[0100] Similarly to Example 1, after raising the temperature to 350° C. at a rate of 5° C./min in a high-purity nitrogen atmosphere, the thermal imidization reaction is carried out for 0.1 hour, and after the film is cooled to room temperature, the composite film E is obtained. The uniform and dense silica layer in the composite film E was found to have a density of 3.0 g/cm.sup.3 and a thickness of 200 nm after an experimental test.

Embodiment 7. Display Panel

[0101] As shown in FIG. 2, an embodiment of the present invention also provides a display panel 20 using the above composite film 10 as a flexible substrate, and the display panel also includes a thin film transistor layer 21 formed on the composite film 10, and an organic light emitting device layer 22 formed on the thin film transistor layer 21. Of course, the display panel 20 may also include other structures of display panels known in the art, such as a package cover plate.

[0102] While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

[0103] The main body of the present invention can be manufactured and used in the industry, and has industrial applicability.