CN117586503A - Polyimide slurry, polyimide film, and preparation methods and applications thereof - Google Patents
Polyimide slurry, polyimide film, and preparation methods and applications thereof Download PDFInfo
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- CN117586503A CN117586503A CN202311557835.2A CN202311557835A CN117586503A CN 117586503 A CN117586503 A CN 117586503A CN 202311557835 A CN202311557835 A CN 202311557835A CN 117586503 A CN117586503 A CN 117586503A
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- polyimide
- polycondensation reaction
- polycondensation
- slurry
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- 229920001721 polyimide Polymers 0.000 title claims abstract description 120
- 239000004642 Polyimide Substances 0.000 title claims abstract description 83
- 239000002002 slurry Substances 0.000 title claims abstract description 46
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000003960 organic solvent Substances 0.000 claims abstract description 20
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 6
- 238000006068 polycondensation reaction Methods 0.000 claims description 122
- NVKGJHAQGWCWDI-UHFFFAOYSA-N 4-[4-amino-2-(trifluoromethyl)phenyl]-3-(trifluoromethyl)aniline Chemical compound FC(F)(F)C1=CC(N)=CC=C1C1=CC=C(N)C=C1C(F)(F)F NVKGJHAQGWCWDI-UHFFFAOYSA-N 0.000 claims description 31
- 238000003756 stirring Methods 0.000 claims description 30
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 26
- 238000002156 mixing Methods 0.000 claims description 20
- 239000000758 substrate Substances 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 18
- SRPWOOOHEPICQU-UHFFFAOYSA-N trimellitic anhydride Chemical compound OC(=O)C1=CC=C2C(=O)OC(=O)C2=C1 SRPWOOOHEPICQU-UHFFFAOYSA-N 0.000 claims description 18
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 14
- 238000000137 annealing Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 11
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 10
- 239000011248 coating agent Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 9
- 238000004528 spin coating Methods 0.000 claims description 7
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000002834 transmittance Methods 0.000 abstract description 11
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052731 fluorine Inorganic materials 0.000 abstract description 7
- 239000011737 fluorine Substances 0.000 abstract description 7
- 125000003118 aryl group Chemical group 0.000 abstract description 4
- 238000004132 cross linking Methods 0.000 abstract description 4
- 239000003795 chemical substances by application Substances 0.000 abstract description 3
- 230000021615 conjugation Effects 0.000 abstract description 2
- 230000000694 effects Effects 0.000 abstract description 2
- 239000002861 polymer material Substances 0.000 abstract description 2
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- 238000001816 cooling Methods 0.000 description 16
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- 239000010408 film Substances 0.000 description 9
- 230000009477 glass transition Effects 0.000 description 9
- 239000012299 nitrogen atmosphere Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000011521 glass Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000000178 monomer Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 238000001291 vacuum drying Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 125000002723 alicyclic group Chemical group 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 230000000930 thermomechanical effect Effects 0.000 description 2
- JPZRPCNEISCANI-UHFFFAOYSA-N 4-(4-aminophenyl)-3-(trifluoromethyl)aniline Chemical compound C1=CC(N)=CC=C1C1=CC=C(N)C=C1C(F)(F)F JPZRPCNEISCANI-UHFFFAOYSA-N 0.000 description 1
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
- G09F9/301—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements flexible foldable or roll-able electronic displays, e.g. thin LCD, OLED
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1003—Preparatory processes
- C08G73/1007—Preparatory processes from tetracarboxylic acids or derivatives and diamines
- C08G73/1028—Preparatory processes from tetracarboxylic acids or derivatives and diamines characterised by the process itself, e.g. steps, continuous
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1039—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors comprising halogen-containing substituents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1042—Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/549—Organic PV cells
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Theoretical Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
Abstract
The invention provides polyimide slurry, a polyimide film, a preparation method and application thereof, and relates to the technical field of high polymer materials. The polyimide slurry comprises polyimide and an organic solvent, wherein the polyimide has a structure shown in a formula I; wherein x is 0.85-0.95, y is 0.15-0.05, and n is the polymerization degree of the polyimide. According to the invention, the performance of polyimide is cooperatively regulated and controlled by utilizing an aromatic rigid structure and a fluorine-containing group, the conjugation of the aromatic structure enhances the acting force between molecular chains, and the tensile strength of polyimide can be improved; the fluorine-containing structure canThe charge transfer effect in a molecular chain is reduced, and the transmittance of polyimide is improved; and adding a crosslinking type end capping agent, and partially crosslinking molecular chain links to reduce the thermal expansion coefficient.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and particularly relates to polyimide slurry, a polyimide film, a preparation method and application thereof.
Background
The flexible display device refers to a flexible electronic product having light weight, flexible and even foldable characteristics, including a flexible thin film transistor liquid crystal display, a flexible organic light emitting display, and the like. Flexible display technology requires materials with higher glass transition temperatures and lower coefficients of thermal expansion, excellent mechanical properties, and higher optical properties. In the preparation process of the flexible display device, in order to improve the performance of the film, the annealing temperature needs to be higher than 350 ℃, and the device and the substrate cannot warp, crack or delaminate in the annealing process, so that the polyimide film is required to have a lower thermal expansion coefficient and a higher glass transition temperature, and meanwhile, in order to improve the shock resistance of the flexible display, the polyimide film is required to have excellent mechanical properties.
Polyimide prepared from monomers containing alicyclic structures and fluoromonomers is commonly used in the prior art as a flexible substrate material, as in the prior art [ J.Appl. Polym. Sci.2022,139 (44), e53082] reports that the glass transition temperature of a transparent polyimide film prepared from a fluorine-containing dianhydride and a fluorine-containing diamine is 347 ℃, the coefficient of thermal expansion is 51ppm/k, the tensile strength is 109MPa, and the 450nm transmittance is 89%; in the prior art [ ACSAppl.Polym.Mater.2023,5,602-613], the glass transition temperature of a transparent polyimide film prepared by using alicyclic structure monomers and fluorine-containing monomers is 406 ℃, the thermal expansion coefficient is 29ppm/k, the tensile strength is 56.5MPa, and the 450nm transmittance is 88%. At present, most transparent polyimide films have a transmittance of more than 85%, a glass transition temperature of more than 350 ℃, and optical transmittance and glass transition temperature of the films can meet the requirements of flexible display technology, but the films still have the defects of higher thermal expansion coefficient (10 ppm/k) and lower tensile strength (250 MPa), and cannot meet the requirements of the prior art.
Disclosure of Invention
The invention aims to provide polyimide slurry, a polyimide film, a preparation method and application thereof, and the polyimide film prepared from the polyimide slurry has lower thermal expansion coefficient and higher tensile strength.
In order to achieve the purpose of the invention, the invention provides the following technical scheme:
a polyimide slurry comprising a polyimide and an organic solvent, the polyimide having a structure according to formula I:
wherein x is 0.85-0.95, y is 0.15-0.05, and n is the polymerization degree of the polyimide.
Preferably, the organic solvent comprises one or more of N-methylpyrrolidone, N-dimethylacetamide and N, N-dimethylformamide; the mass percentage of polyimide in the polyimide slurry is 18-20%.
The invention also provides a preparation method of the polyimide slurry, which is characterized by comprising the following steps:
mixing 2,2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride and an organic solvent, and performing a first polycondensation reaction to obtain a first polycondensation product system;
mixing the first polycondensation product system with hexafluorodianhydride, and performing a second polycondensation reaction to obtain a second polycondensation product system;
heating the second polycondensation product, and performing a third polycondensation reaction to obtain a third polycondensation product system;
and mixing the third polycondensation product system with trimellitic anhydride, and performing a fourth polycondensation reaction to obtain the polyimide slurry.
Preferably, the molar ratio of the 2,2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride, hexafluorodianhydride and trimellitic anhydride is 1.0-1.02:0.85-0.95:0.05-0.15:0.02-0.04.
Preferably, the temperatures of the first polycondensation reaction, the second polycondensation reaction and the fourth polycondensation reaction are independently 15-35 ℃; the temperature of the third polycondensation reaction is 60-70 ℃; the first polycondensation reaction, the second polycondensation reaction, the third polycondensation reaction and the fourth polycondensation reaction are carried out under stirring conditions, and the stirring speed is independently 100-250 rpm.
Preferably, the time of the first polycondensation reaction is 1.5 to 2 hours; the second polycondensation reaction time is 20-30 h; the time of the third polycondensation reaction is 1-2 h; the time of the fourth polycondensation reaction is 1.5-2 h.
The invention also provides a polyimide film, which is prepared by coating polyimide slurry on a substrate, and sequentially drying and annealing; the polyimide slurry is prepared by the polyimide slurry prepared by the technical scheme or the preparation method prepared by the technical scheme.
Preferably, the drying temperature is 100-110 ℃ and the drying time is 1-1.5 h; the annealing temperature is 50-400 ℃, and the heat preservation time is 4-5 h.
Preferably, the coating mode is spin coating; the rotating speed of the spin coating is 500-1000 rpm, and the time is 80-100 s.
The invention also provides application of the polyimide film in flexible display devices.
The invention provides polyimide slurry, which comprises polyimide and an organic solvent, wherein the polyimide has a structure shown in a formula I:
wherein x is 0.85-0.95, y is 0.15-0.05, and n is the polymerization degree of the polyimide. According to the invention, the performance of polyimide is cooperatively regulated and controlled by utilizing an aromatic rigid structure and a fluorine-containing group, the conjugation of the aromatic structure enhances the acting force between molecular chains, and the tensile strength of polyimide can be improved; and the fluorine-containing structure can reduce the charge transfer effect in a molecular chain and improve the optical transmittance of polyimide.
The invention also provides a preparation method of the polyimide film, and the tensile strength of the film is effectively improved by adopting an annealing process so as to meet the technical requirements of flexible display. In addition, the invention adopts trimellitic anhydride to carry out a fourth polycondensation reaction, and the trimellitic anhydride is used as a crosslinking type end capping agent, so that molecular chain units can be partially crosslinked, and the thermal expansion coefficient of the polyimide film is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of the preparation of polyimide slurry according to the present invention;
FIG. 2 is a flow chart of the preparation of polyimide film according to the present invention.
Detailed Description
The invention provides polyimide slurry, which comprises polyimide and an organic solvent, wherein the polyimide has a structure shown in a formula I:
wherein x is 0.85-0.95, y is 0.15-0.05, and n is the polymerization degree of the polyimide.
In the present invention, x is 0.85 to 0.95, preferably 0.90; y is 0.15 to 0.05, preferably 0.10; n is the polymerization degree of the polyimide. In the present invention, n is preferably 10 to 10000.
In the present invention, the organic solvent preferably includes one or more of N-methylpyrrolidone (NMP), N-Dimethylacetamide (DMAC) and N, N-Dimethylformamide (DMF), more preferably N-methylpyrrolidone. In the present invention, the mass percentage of polyimide in the polyimide slurry is preferably 18 to 20%, more preferably 19%.
The invention also provides a preparation method of the polyimide slurry, which comprises the following steps:
mixing 2,2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride and an organic solvent, and performing a first polycondensation reaction to obtain a first polycondensation product system;
mixing the first polycondensation product system with hexafluorodianhydride, and performing a second polycondensation reaction to obtain a second polycondensation product system;
heating the second polycondensation product, and performing a third polycondensation reaction to obtain a third polycondensation product system;
and mixing the third polycondensation product system with trimellitic anhydride, and performing a fourth polycondensation reaction to obtain the polyimide slurry.
In the present invention, all the production materials are preferably commercially available products unless otherwise specified.
The polyimide is prepared by taking 2,2 '-bis (trifluoromethyl) benzidine (TFMB), pyromellitic dianhydride (PMDA), hexafluorodianhydride (6 FDA) and trimellitic anhydride (TMA) as monomers, wherein the molar ratio of the 2,2' -bis (trifluoromethyl) benzidine to the pyromellitic dianhydride to the hexafluorodianhydride to the trimellitic anhydride is preferably 1.0-1.02:0.85-0.95:0.05-0.15:0.02-0.04, and more preferably 1:0.88:0.0986:0.0286. The method for preparing the polyimide paste according to the present invention will be described in detail.
The invention mixes 2,2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride and organic solvent to carry out a first polycondensation reaction to obtain a first polycondensation product system.
In the present invention, 2' -bis (trifluoromethyl) benzidine is preferably mixed with a part of an organic solvent to dissolve 2,2' -bis (trifluoromethyl) benzidine, thereby obtaining a 2,2' -bis (trifluoromethyl) benzidine solution. In the present invention, the mixing is preferably performed under stirring conditions, and the stirring speed is preferably 200 to 300rpm, more preferably 250rpm; the time is preferably 20 to 40 minutes, more preferably 30 minutes. In the present invention, the mass ratio of the part of the organic solvent to 2,2' -bis (trifluoromethyl) benzidine is preferably 1:4 to 5, more preferably 1:4.26.
In the present invention, the partial organic solvent is preferably heated before mixing, and the heating temperature is preferably 27 to 35 ℃, more preferably 30 ℃; the time is preferably 10 to 20 minutes, more preferably 15 minutes. In the present invention, the heating is preferably performed under stirring conditions, and the stirring speed is preferably 200 to 300rpm, more preferably 250rpm.
After obtaining 2,2 '-bis (trifluoromethyl) benzidine solution, the invention mixes the para-2, 2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride and the rest organic solvent to carry out a first polycondensation reaction to obtain a first polycondensation product system. In the present invention, the mixing is preferably performed under stirring conditions, and the stirring speed is preferably 100 to 200rpm, more preferably 150rpm. In the present invention, the temperature of the mixing is preferably 10 to 15 ℃, more preferably 10 ℃. In the present invention, the mass ratio of the residual organic solvent to pyromellitic dianhydride is preferably 1:4 to 5, more preferably 1:4.26.
In the present invention, the first polycondensation reaction is preferably performed under stirring; the stirring rate is preferably 150 to 250rpm, more preferably 200rpm. In the present invention, the temperature of the first polycondensation reaction is preferably 20 to 30 ℃, more preferably 25 ℃; the time of the first polycondensation reaction is preferably 1.5 to 2.5 hours, more preferably 2 hours.
After the first polycondensation reaction, the method is preferably carried out without any post-treatment, and the obtained first polycondensation product system and the hexafluorodianhydride are directly mixed for carrying out a second polycondensation reaction to obtain a second polycondensation product system.
The invention preferably comprises adding additional organic solvent during the second polycondensation reaction, in particular by mixing the first polycondensation product system, the hexafluorodianhydride and the additional organic solvent. In the present invention, the mixing is preferably performed under stirring conditions, and the stirring speed is preferably 100 to 200rpm, more preferably 150rpm. In the present invention, the temperature of the mixing is preferably 10 to 15 ℃, more preferably 10 ℃. In the present invention, the mass ratio of the additional organic solvent to the hexafluorodianhydride is preferably 1:4 to 5, more preferably 1:4.26.
In the present invention, the temperature and stirring rate of the second polycondensation reaction and the first polycondensation reaction are preferably uniform. In the present invention, the time of the second polycondensation reaction is preferably 20 to 30 hours, more preferably 20 to 25 hours.
After the second polycondensation reaction, the present invention preferably directly heats the obtained second polycondensation product without any post-treatment, and performs a third polycondensation reaction to obtain a third polycondensation product system. In the present invention, the temperature of the third polycondensation reaction is preferably 60 to 70 ℃, more preferably 65 ℃; the time of the third polycondensation reaction is preferably 1 to 2 hours, more preferably 1.5 hours. In the present invention, the third polycondensation reaction is performed by heating, and a part of the molecular chains can be depolymerized, thereby reducing the molecular weight distribution.
After the third polycondensation reaction, the present invention preferably directly mixes the obtained third polycondensation product system with trimellitic anhydride without any post-treatment, and performs a fourth polycondensation reaction to obtain the polyimide slurry. The invention adopts trimellitic anhydride to carry out the fourth polycondensation reaction, and the trimellitic anhydride is used as a crosslinking type end capping agent, so that molecular chain units can be partially crosslinked, and the thermal expansion coefficient of the polyimide film is reduced.
In the present invention, the mixing is preferably performed under stirring conditions, and the stirring speed is preferably 100 to 200rpm, more preferably 150rpm. In the present invention, the temperature and stirring rate of the fourth polycondensation reaction and the first polycondensation reaction are preferably uniform. In the present invention, the time of the fourth polycondensation reaction is preferably 1.5 to 2.5 hours, more preferably 2 hours.
In the present invention, the first polycondensation reaction, the second polycondensation reaction, the third polycondensation reaction, and the fourth polycondensation reaction are preferably performed under a protective gas atmosphere; the shielding gas is preferably one of nitrogen, oxygen and nitrogen, more preferably nitrogen; in the present invention, the flow rate of the shielding gas is preferably in the range of 2 to 7mL/min, more preferably 5mL/min.
The invention also provides a polyimide film, which is prepared by coating polyimide slurry on a substrate, and sequentially drying and annealing; the polyimide slurry is prepared by the polyimide slurry prepared by the technical scheme or the preparation method prepared by the technical scheme.
In the present invention, the thickness of the polyimide film is preferably 8 to 15. Mu.m, more preferably 10. Mu.m.
The invention applies polyimide slurry to a substrate to obtain a substrate coated with polyimide slurry. In the present invention, the coating is preferably preceded by deaerating the polyimide slurry. In the present invention, the defoaming mode is preferably vacuum defoaming, and the defoaming time is preferably 0.5 to 1 hour. In the present invention, the substrate preferably includes a glass substrate or a quartz substrate, more preferably a glass substrate. In the present invention, the pre-coating further preferably includes sequentially cleaning and drying the substrate. The invention preferably uses deionized water for cleaning. In the present invention, the drying preferably includes drying with compressed air and then vacuum drying; the temperature of the vacuum drying is preferably 50-80 ℃, more preferably 60 ℃; the time is preferably 0.5 to 1 hour.
In the present invention, the coating means is preferably spin coating; the spin-coating speed is preferably 500 to 1000rpm, more preferably 800rpm; the time is preferably 80 to 100s, more preferably 100s.
In the present invention, the post-coating further preferably includes deaerating the substrate coated with the polyimide paste. In the present invention, the defoaming method is preferably the same as the defoaming method described above.
After the substrate coated with the polyimide paste is obtained, the substrate coated with the polyimide paste is sequentially dried and annealed. In the present invention, the drying temperature is preferably 100 to 120 ℃, more preferably 100 ℃; the time is preferably 1 to 1.5 hours, more preferably 1 hour. In the invention, the annealing temperature is preferably 50-400 ℃, and the heat preservation time is preferably 4-6 h. In a specific embodiment of the present invention, the annealing is preferably: the temperature is kept between 100 and 120 ℃ for 0.5 to 1 hour, between 200 and 220 ℃ for 0.5 to 1 hour, between 260 and 280 ℃ for 0.5 to 1 hour, between 380 and 400 ℃ for 0.2 to 0.5 hour, and between 30 and 50 ℃ for 1.5 to 2 hours. In the present invention, the annealed oxygen content is preferably below 10000rpm, more preferably 2000rpm.
In the present invention, the polyimide film is preferably peeled off after the annealing. In the present invention, the stripping means is preferably a method of stripping a polyimide film by washing with water; the temperature of the water washing is preferably 70 to 80 ℃, more preferably 80 ℃. In the present invention, the polyimide film is preferably dried after the water washing; the drying temperature is preferably 100-120 ℃ and the drying time is preferably 1-2 h.
The invention also provides application of the polyimide film in flexible display devices.
For further explanation of the present invention, the polyimide paste and polyimide film provided by the present invention will be described in detail with reference to the accompanying drawings and examples, which should not be construed as limiting the scope of the present invention.
Example 1
Polyimide slurry is prepared according to the flow chart shown in fig. 1, and the specific steps are as follows:
85.51g of N-methylpyrrolidone was placed in a three-necked flask under a nitrogen atmosphere (nitrogen flow: 5 mL/min), stirred at 25℃and 250rpm for 10min, and then mixed with 0.045mol (14.37 g) of 2,2 '-bis (trifluoromethyl) benzidine and 10.69g N-methylpyrrolidone under stirring for another 30min to obtain a 2,2' -bis (trifluoromethyl) benzidine solution; after cooling to 10 ℃, 0.04mol (8.72 g) of pyromellitic dianhydride, 5.34g N-methyl pyrrolidone and the 2,2' -bis (trifluoromethyl) benzidine solution are stirred and mixed for 0.5h under the condition of 150rpm, then the temperature is increased to 25 ℃, and the mixture is stirred for 2h under the condition of 200rpm, so as to obtain a first polycondensation product system;
cooling the first polycondensation product system to 10 ℃, stirring and mixing 0.0044mol (1.97 g) of hexafluorodianhydride, 5.34g N-methyl pyrrolidone and the first polycondensation product system for 0.5h under the condition of 150rpm, then heating to 25 ℃, and stirring for 24h under the condition of 200rpm to obtain a second polycondensation product system;
heating the second polycondensation product system at 65 ℃ for 1h, and cooling to 25 ℃ to obtain a third polycondensation product system;
0.0013mol (0.26 g) of trimellitic anhydride and the third polycondensation product system were mixed at 25℃and 150rpm, and then stirred at 25℃and 100rpm for 2 hours to obtain a polyimide slurry.
Comparative example 1
85.51g of N-methylpyrrolidone was placed in a three-necked flask under a nitrogen atmosphere (nitrogen flow: 5 mL/min), stirred at 25℃and 250rpm for 10min, and then mixed with 0.045mol (14.37 g) of 2,2 '-bis (trifluoromethyl) benzidine and 10.69g N-methylpyrrolidone under stirring for another 30min to obtain a 2,2' -bis (trifluoromethyl) benzidine solution; after cooling to 10 ℃, 0.04mol (8.72 g) of pyromellitic dianhydride, 0.0044mol (1.97 g) of hexafluorodianhydride, 10.68g N-methylpyrrolidone and the above 2,2' -bis (trifluoromethyl) benzidine solution were stirred and mixed for 0.5h at 150rpm, then heated to 25 ℃ and stirred for 2h at 200rpm to obtain a first polycondensation product system;
heating the first polycondensation product system at 65 ℃ for 1h, and cooling to 25 ℃ to obtain a second polycondensation product system;
0.0013mol (0.25 g) of trimellitic anhydride was mixed with the above second polycondensation product system at 150rpm while maintaining 25℃and then stirred at 100rpm for 2 hours at 25℃to obtain a polyimide slurry.
Comparative example 2
100.06g of N-methylpyrrolidone was placed in a three-necked flask under a nitrogen atmosphere (nitrogen flow: 5 mL/min), stirred at 25℃and 250rpm for 10min, and then mixed with 0.0505mol (16.17 g) of 2,2 '-bis (trifluoromethyl) benzidine and 12.51g N-methylpyrrolidone under stirring for another 30min to obtain a 2,2' -bis (trifluoromethyl) benzidine solution; after cooling to 10 ℃, 0.04mol (8.72 g) of pyromellitic dianhydride, 0.01mol (4.44 g) of hexafluorodianhydride, 12.51g N-methylpyrrolidone and the 2,2' -bis (trifluoromethyl) benzidine solution were stirred and mixed for 0.5h under the condition of 150rpm, and then the temperature was raised to 25 ℃ and stirred for 2h under the condition of 200rpm to obtain a first polycondensation product system;
heating the first polycondensation product system at 65 ℃ for 1h, and cooling to 25 ℃ to obtain a second polycondensation product system;
0.0015mol (0.29 g) of trimellitic anhydride and the second polycondensation product system were mixed at 150rpm while maintaining 25℃and then stirred at 100rpm for 2 hours at 25℃to obtain a polyimide slurry.
Comparative example 3
118.76g of N-methylpyrrolidone was placed in a three-necked flask under a nitrogen atmosphere (nitrogen flow: 5 mL/min), stirred at 25℃and 250rpm for 10min, and then mixed with 0.0577mol (18.48 g) of 2,2 '-bis (trifluoromethyl) benzidine and 14.85g N-methylpyrrolidone under stirring for another 30min to obtain a 2,2' -bis (trifluoromethyl) benzidine solution; after cooling to 10 ℃, 0.04mol (8.72 g) of pyromellitic dianhydride, 0.0171mol (7.62 g) of hexafluorodianhydride, 14.85g N-methylpyrrolidone and the above 2,2' -bis (trifluoromethyl) benzidine solution were stirred and mixed for 0.5 hours at 150rpm, then heated to 25 ℃ and stirred for 2 hours at 200rpm to obtain a first polycondensation product system;
heating the first polycondensation product system at 65 ℃ for 1h, and cooling to 25 ℃ to obtain a second polycondensation product system;
0.0017mol (0.33 g) of trimellitic anhydride and the second polycondensation product system were mixed at 25℃and 150rpm, and then stirred at 25℃and 100rpm for 2 hours to obtain a polyimide slurry.
Comparative example 4
85.51g of N-methylpyrrolidone was placed in a three-necked flask under a nitrogen atmosphere (nitrogen flow: 5 mL/min), stirred at 25℃and 250rpm for 10min, and then mixed with 0.045mol (14.37 g) of 2,2 '-bis (trifluoromethyl) benzidine and 10.69g N-methylpyrrolidone under stirring for another 30min to obtain a 2,2' -bis (trifluoromethyl) benzidine solution; after cooling to 10 ℃, 0.04mol (8.72 g) of pyromellitic dianhydride, 5.34g N-methyl pyrrolidone and the 2,2' -bis (trifluoromethyl) benzidine solution are stirred and mixed for 0.5h under the condition of 150rpm, then the temperature is increased to 25 ℃, and the mixture is stirred for 2h under the condition of 200rpm, so as to obtain a first polycondensation product system;
cooling the first polycondensation product system to 10 ℃, stirring and mixing 0.0044mol (1.97 g) of hexafluorodianhydride, 5.34g N-methyl pyrrolidone and the first polycondensation product system for 0.5h under the condition of 150rpm, then heating to 25 ℃, and stirring for 24h under the condition of 200rpm to obtain a second polycondensation product system;
heating the second polycondensation product system at 65 ℃ for 1h, and cooling to 25 ℃ to obtain a third polycondensation product system;
0.0009mol (0.17 g) of trimellitic anhydride and the above third polycondensation product system were mixed at 25℃and 150rpm, and then stirred at 25℃and 100rpm for 2 hours, to obtain a polyimide slurry.
Comparative example 5
85.51g of N-methylpyrrolidone was placed in a three-necked flask under a nitrogen atmosphere (nitrogen flow: 5 mL/min), stirred at 25℃and 250rpm for 10min, and then mixed with 0.045mol (14.37 g) of 2,2 '-bis (trifluoromethyl) benzidine and 10.69g N-methylpyrrolidone under stirring for another 30min to obtain a 2,2' -bis (trifluoromethyl) benzidine solution; after cooling to 10 ℃, 0.04mol (8.72 g) of pyromellitic dianhydride, 5.34g N-methyl pyrrolidone and the 2,2' -bis (trifluoromethyl) benzidine solution are stirred and mixed for 0.5h under the condition of 150rpm, then the temperature is increased to 25 ℃, and the mixture is stirred for 2h under the condition of 200rpm, so as to obtain a first polycondensation product system;
cooling the first polycondensation product system to 10 ℃, stirring and mixing 0.0044mol (1.97 g) of hexafluorodianhydride, 5.34g N-methyl pyrrolidone and the first polycondensation product system for 0.5h under the condition of 150rpm, then heating to 25 ℃, and stirring for 24h under the condition of 200rpm to obtain a second polycondensation product system;
heating the second polycondensation product system at 65 ℃ for 1h, and cooling to 25 ℃ to obtain a third polycondensation product system;
0.00135mol (0.259 g) of trimellitic anhydride and the third polycondensation product system were mixed at 25℃and 150rpm, and then stirred at 25℃and 100rpm for 2 hours to obtain a polyimide slurry.
Application example
The polyimide film is prepared according to the flow chart shown in fig. 2, and the specific steps are as follows:
placing the polyimide slurry in a vacuum oven, and vacuum defoaming for 0.5h at 25 ℃ to obtain pretreated polyimide slurry;
cleaning a glass substrate (8 inches) by using ionized water, drying the glass substrate by using compressed air, and then placing the glass substrate into a vacuum drying oven to heat for 0.5h at 60 ℃ to obtain a pretreated glass substrate;
respectively measuring 20mL of the pretreated polyimide slurry, spin-coating for 100s at 500rpm, and obtaining a polyimide wet film with uniform thickness on the surface of the glass substrate;
placing the polyimide wet film into a vacuum oven, vacuum defoaming for 0.5h at 25 ℃, then placing the polyimide wet film into a blast drying oven, and heating for 1h at 100 ℃ to remove the solvent to obtain a polyimide dry film;
and (3) placing the polyimide dry film in an anaerobic oven for annealing, wherein the annealing procedure is as follows: nitrogen protection, wherein the oxygen content is lower than 10000ppm; preserving heat at 120 ℃ for 1h, preserving heat at 220 ℃ for 0.5h, preserving heat at 280 ℃ for 0.5h, preserving heat at 400 ℃ for 0.2h, preserving heat at 50 ℃ for 2h, naturally cooling to room temperature, taking out, placing in deionized water, heating to 80 ℃, and stripping to obtain a polyimide film blank; and (3) placing the polyimide film blank into a blast oven to be dried for 1h at the temperature of 100 ℃ to obtain the polyimide film. Polyimide slurries used in this application example were derived from example 1 and comparative examples 1 to 5, respectively, and finally prepared polyimide films were designated as sample 1 and samples 2 to 6 in this order.
Test case
The glass transition temperature (Tg), coefficient of Thermal Expansion (CTE), average transmittance, tensile strength, elongation and elastic modulus of samples 1 and samples 2 to 6 were tested, and the results are shown in table 1.
The specific test method comprises the following steps:
glass transition temperature was measured using a thermo-mechanical analyzer (TMA), equipment model TATMAQ400EM, under the following conditions: the nitrogen atmosphere, the pre-loading force is 0.05N, and the temperature rising rate is 10K/min;
coefficient of Thermal Expansion (CTE) was measured using a thermo-mechanical analyzer (TMA), device model TATMA Q400EM, under the following conditions: the nitrogen atmosphere, the preloading force is 0.05N, the heating rate is 10K/min, and the average thermal expansion coefficient within the range of 50-350 ℃ is measured;
the transmittance was measured using an ultraviolet spectrophotometer, device model UV7600PRO, with the transmittance measured at a wavelength of 450nm as a 450nm transmittance;
tensile strength, elongation and modulus of elasticity were measured using a tensile tester, equipment model Labthink C610, 500 mm/min.
TABLE 1 polyimide film Performance test results
As shown in the results of Table 1, the polyimide film prepared by the invention has a glass transition temperature of 407 ℃, a thermal expansion coefficient of 5.15ppm/K, an average transmittance of 86%, a tensile strength of 316MPa, an elongation of 20.9% and an elastic modulus of 6.7GPa, has better performance than the polyimide film in the comparative example, and can meet the technical requirements of flexible display.
Although the foregoing embodiments have been described in some, but not all, embodiments of the invention, it should be understood that other embodiments may be devised in accordance with the present embodiments without departing from the spirit and scope of the invention.
Claims (10)
1. A polyimide slurry comprising a polyimide and an organic solvent, the polyimide having a structure according to formula I:
wherein x is 0.85-0.95, and y is 0.15-0.05; n is the polymerization degree of the polyimide.
2. The polyimide slurry according to claim 1, wherein the organic solvent comprises one or more of N-methylpyrrolidone, N-dimethylacetamide and N, N-dimethylformamide; the mass percentage of polyimide in the polyimide slurry is 18-20%.
3. The method for producing a polyimide slurry according to any one of claims 1 to 2, comprising the steps of:
mixing 2,2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride and an organic solvent, and performing a first polycondensation reaction to obtain a first polycondensation product system;
mixing the first polycondensation product system with hexafluorodianhydride, and performing a second polycondensation reaction to obtain a second polycondensation product system;
heating the second polycondensation product, and performing a third polycondensation reaction to obtain a third polycondensation product system;
and mixing the third polycondensation product system with trimellitic anhydride, and performing a fourth polycondensation reaction to obtain the polyimide slurry.
4. The method according to claim 3, wherein the molar ratio of 2,2' -bis (trifluoromethyl) benzidine, pyromellitic dianhydride, hexafluorodianhydride and trimellitic anhydride is 1.0 to 1.02:0.85 to 0.95:0.05 to 0.15:0.02 to 0.04.
5. The method according to claim 3, wherein the temperatures of the first polycondensation reaction, the second polycondensation reaction, and the fourth polycondensation reaction are independently 15 to 35 ℃; the temperature of the third polycondensation reaction is 60-70 ℃; the first polycondensation reaction, the second polycondensation reaction, the third polycondensation reaction and the fourth polycondensation reaction are carried out under stirring conditions, and the stirring speed is independently 100-250 rpm.
6. The method according to claim 3 or 5, wherein the time of the first polycondensation reaction is 1.5 to 2 hours; the second polycondensation reaction time is 20-30 h; the time of the third polycondensation reaction is 1-2 h; the time of the fourth polycondensation reaction is 1.5-2 h.
7. A polyimide film is characterized in that the polyimide film is prepared by coating polyimide slurry on a substrate, and sequentially drying and annealing; the polyimide slurry is the polyimide slurry prepared by any one of claims 1-2 or the preparation method of any one of claims 3-6.
8. The polyimide film according to claim 7, wherein the drying temperature is 100 to 110 ℃ for 1 to 1.5 hours; the annealing temperature is 50-400 ℃, and the heat preservation time is 4-5 h.
9. The polyimide film according to claim 7, wherein the coating is spin coating; the rotating speed of the spin coating is 500-1000 rpm, and the time is 80-100 s.
10. Use of the polyimide film according to any one of claims 7 to 9 in flexible display devices.
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