WO2023231807A1 - 聚合物前驱体、聚合物薄膜及其制备方法 - Google Patents

聚合物前驱体、聚合物薄膜及其制备方法 Download PDF

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WO2023231807A1
WO2023231807A1 PCT/CN2023/095283 CN2023095283W WO2023231807A1 WO 2023231807 A1 WO2023231807 A1 WO 2023231807A1 CN 2023095283 W CN2023095283 W CN 2023095283W WO 2023231807 A1 WO2023231807 A1 WO 2023231807A1
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aromatic
polymer
dianhydride
polymer film
film
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PCT/CN2023/095283
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English (en)
French (fr)
Inventor
张艺
贝润鑫
龙禹波
黄海滔
江雪双
吴敏铭
蒋星
苗杰
吴琦
秦德君
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华为技术有限公司
中山大学
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Publication of WO2023231807A1 publication Critical patent/WO2023231807A1/zh

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    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions 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 C08L61/00 - C08L77/00
    • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors

Definitions

  • the embodiments of the present application relate to the technical field of polymer film preparation, and in particular to a polymer precursor, a polymer film and a preparation method thereof.
  • transparent polymer materials to replace traditional glass substrates to prepare various electronic components (such as thin film transistors or transparent electrodes, etc.) is currently a key research direction in the industry.
  • transparent polyimide has relatively excellent thermal stability, high glass transition temperature Tg, high mechanical strength and low thermal expansion coefficient CTE. It is the most promising alternative to glass substrates to realize electronic components. Alternative materials for lightweight and flexible devices.
  • the above-mentioned electronic components must undergo high-temperature processes during the preparation process.
  • the low-temperature polysilicon (LTPS) process for manufacturing organic light-emitting diode (OLED) devices has a process temperature close to 500°C.
  • the existing transparent polyimide materials are difficult to meet the above-mentioned high-temperature process.
  • some aromatic polyimide materials can withstand temperatures above 500°C for a short period of time, the yellowness index of such aromatic polyimide is very high ( The yellowness index YI of 15 ⁇ m thickness is as high as 46.0)), and the transmittance in the visible light region is low ( ⁇ 60%).
  • the embodiments of the present application provide a polymer precursor, a polymer film and a preparation method thereof.
  • the polyamic acid, the precursor of the polyimide is specially structurally designed and prepared into a polyimide using a specific process.
  • Thin film, this polyimide film has both good thermodynamic properties and good optical properties, and can meet the application needs of flexible electronic components in the display field.
  • the first aspect of the embodiment of the present application provides a polymer precursor
  • the polymer precursor is polyamic acid
  • the polymer precursor includes repeating units derived from aromatic dianhydrides and aromatic diamines , at least one carbon atom on the aromatic ring in the aromatic dianhydride and/or the aromatic diamine is connected to a fluorine atom through a C-F single bond.
  • the polyamic acid provided in the embodiment of the present application is a precursor material for preparing polyimide.
  • the polyamic acid includes repeating units derived from aromatic dianhydrides and aromatic diamines. That is, the polyamic acid adopts aromatic compounds with aromatic structures.
  • the dianhydride and aromatic diamine are copolymerized, and the use of monomers with aromatic structure is beneficial to the polyimide film to obtain good thermodynamic properties; in addition, at least one carbon on the aromatic ring in the aromatic dianhydride and/or aromatic diamine
  • the atoms are connected to fluorine atoms through CF single bonds, so that the polyimide molecular chains can be partially cross-linked through CF single bonds through a specific film forming process, thereby further improving the thermodynamic properties of polyimide (including thermal stability and Dimensional stability, etc.), while having good optical properties (including high light transmittance rate, low yellowness index, etc.).
  • At least one carbon atom on the aromatic ring in the aromatic diamine is connected to a fluorine atom through a C-F single bond, and the structure of the aromatic diamine is as shown in the general formula (1):
  • R represents an aromatic group with 1 to 10 benzene rings, and at least one carbon atom on some or all of the benzene rings in R is connected to a fluorine atom through a C-F single bond, and no fluorine is connected to the benzene ring.
  • a hydrogen atom, alkyl group, fluoroalkyl group or phenyl group is attached to the carbon position of the atom.
  • Fluorine-containing aromatic diamine monomers with the structure of general formula (1) are used as raw materials for the preparation of polyimide precursors, which can effectively reduce the formation of charge transfer complexes (CTC), and after specific process treatment, the polyimide Amine can partially cross-link the molecular chain through C-F single bonds, thereby effectively improving the transparency of the polyimide film and giving the polyimide film excellent thermodynamic properties such as high glass transition temperature, high thermal weight loss temperature, and low thermal expansion coefficient.
  • CTC charge transfer complexes
  • R can specifically be a substituted benzene ring with one benzene ring, or a substituted biphenyl structure with two or more benzene rings, etc.
  • the substituted biphenyl structure can specifically be a substituted diphenyl structure, substituted biphenyl structure, etc. terphenyl structure, substituted tetraphenyl structure, etc.
  • R is a substituted benzene ring.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-A1) or (1-A2),
  • the group connected at the position, R 1 can be a hydrogen atom, an alkyl group, a fluoroalkyl group or a phenyl group.
  • R is a substituted diphenyl structure.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-B),
  • R 2 on the two benzene rings can be independently a hydrogen atom, an alkyl group, a fluoroalkyl group or a phenyl group.
  • R is a substituted terphenyl structure.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-C),
  • the group connected to the carbon position, R 3 on the three benzene rings can be independently a hydrogen atom, an alkane base, fluoroalkyl or phenyl.
  • R is a substituted tetraphenyl structure.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-D),
  • R 4 on the four benzene rings can be independently a hydrogen atom, an alkyl group, a fluoroalkyl group or a phenyl group.
  • the aromatic diamine is selected from any one or more of formulas (1-1) to (1-12):
  • aromatic diamine monomers in the embodiments of the present application are easy to obtain and have a rigid non-planar structure, which is conducive to imparting good transparency and thermal properties to the polyimide.
  • the aromatic dianhydride is selected from any one or more of formulas (2-1) to (2-17):
  • the rigid non-planar structure of the aromatic dianhydride in the embodiment of the present application can effectively inhibit the accumulation of polymer molecular chains and give the polyimide good transparency and thermal properties.
  • the molar proportion of the structural units derived from the aromatic dianhydride is 50% to 100%. Controlling the molar proportion of structural units derived from aromatic dianhydrides at a higher proportion is beneficial to improving the thermodynamic properties of polyimide films.
  • the polyamic acid further includes repeating units derived from the dianhydride of a rigid alicyclic structure and the aromatic diamine.
  • the molar proportion of the structural units derived from the dianhydride of the rigid alicyclic structure is 5% to 50%. Controlling the amount of the dianhydride monomer with a rigid alicyclic structure to a smaller amount is beneficial to obtaining better thermodynamic properties while improving the optical properties of the polyimide film.
  • the dianhydride with a rigid alicyclic structure includes any one or more of the formulas (3-1) to (3-4):
  • the second aspect of the embodiments of the present application provides a precursor solution, that is, a polyamic acid solution.
  • the precursor solution includes the polymer precursor described in the first aspect of the embodiments of the present application and an organic solvent.
  • the polyimide film prepared from the precursor solution has both good thermodynamic properties and optical properties.
  • the solid content of the precursor solution is 5%-50%. Suitable solid content is conducive to passing through the The film process obtains a polyimide film with suitable thickness and good comprehensive properties.
  • the organic solvent includes N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), ⁇ -butyrolactone (GBL), N-methyl One or more of pyrrolidone (NMP) and m-cresol (m-Cresol).
  • DMAc N,N-dimethylacetamide
  • DMF N,N-dimethylformamide
  • GBL ⁇ -butyrolactone
  • NMP N-methyl One or more of pyrrolidone
  • m-Cresol m-cresol
  • the third aspect of the embodiments of the present application provides a method for preparing a polymer film, including:
  • the precursor solution described in the second aspect of the embodiment of the present application is coated on the substrate. After removing the solvent, it is placed in a vacuum or protective atmosphere for heat treatment to complete imidization to obtain a polymer film, that is, polyimide. film;
  • the heat treatment includes raising the temperature from room temperature to 355°C-450°C through a gradient heating program or a continuous heating program, and maintaining the temperature at 355°C-450°C for 0.05h-2h.
  • the gradient heating program includes: rising from room temperature to 60°C-100°C and maintaining it for 0.5h-2h, then raising the temperature to 130°C-180°C and maintaining it for 0.5h-2h, and then raising the temperature to 230°C-300°C. °C/0.5h-2h, then heat up to 355°C-450°C.
  • the continuous heating program includes: continuously heating from room temperature to 355°C-450°C at a heating rate of 1-10°C/m11.
  • the preparation method of the polymer film provided in the embodiments of the present application has a simple process and is easy to realize industrial production.
  • the fourth aspect of the embodiment of the present application provides a polymer film, that is, a polyimide film.
  • the polyimide film is prepared from the precursor solution described in the second aspect of the embodiment of the present application, or is prepared from the precursor solution of the second aspect of the embodiment of the present application. It is prepared by the preparation method described in the three aspects.
  • the polyimide film has both good thermodynamic properties and optical properties.
  • a fifth aspect of the embodiment of the present application provides a polymer film, namely a polyimide film, the polyimide film includes a polymer (ie, polyimide), the polymer includes an aromatic dianhydride derived from and a repeating unit of an aromatic diamine, wherein at least one carbon atom on the aromatic ring in the aromatic dianhydride and/or the aromatic diamine is connected to a fluorine atom through a C-F single bond.
  • a polymer film namely a polyimide film
  • the polyimide film includes a polymer (ie, polyimide)
  • the polymer includes an aromatic dianhydride derived from and a repeating unit of an aromatic diamine, wherein at least one carbon atom on the aromatic ring in the aromatic dianhydride and/or the aromatic diamine is connected to a fluorine atom through a C-F single bond.
  • some of the polymer molecules are cross-linked through the C-F single bonds.
  • the sixth aspect of the embodiment of the present application provides a polymer film, that is, a polyimide film.
  • the average light transmittance of the polyimide film in the range of 4001m-7801m is ⁇ 75%; yellowness based on ASTM E313 standard Value YI ⁇ 15; glass transition temperature Tg ⁇ 400°C; thermal expansion coefficient CTE ⁇ 10ppm/K in the range of 40°C to 4400°C; 1% thermogravimetric loss temperature under nitrogen >500°C.
  • the polyimide film has both good thermodynamic properties and optical properties.
  • the polymer film includes a polymer, the polymer includes repeating units derived from an aromatic dianhydride and an aromatic diamine, the aromatic dianhydride and/or the aromatic diamine At least one carbon atom on the aromatic ring is connected to a fluorine atom through a C-F single bond.
  • the thickness of the polymer film is 2 ⁇ m to 100 ⁇ m.
  • Embodiments of the present application provide applications of the polymer film described in the fourth, fifth or sixth aspect in the preparation of flexible substrates, communication equipment insulation materials, electronic equipment insulation materials, motor insulation materials, and electrical insulation materials.
  • Polyimide film has both good thermodynamic properties and optical properties, and can meet the needs of high heat resistance and high transparency.
  • Embodiments of the present application also provide an electronic device, which includes the polymer film described in the fourth, fifth or sixth aspect of the embodiments of the present application.
  • Polymer films can be used as substrates, insulating spacers, protective layers, covering films, covers, etc. for electronic devices.
  • the electronic device includes a transparent antenna, a flexible circuit board, a light-emitting device, a display device, a display device, a lighting device or a solar cell.
  • An embodiment of the present application also provides a device, which is an electronic device or a communication device, and the device includes the polymer film described in the fourth, fifth or sixth aspect of the embodiment of the present application; or includes the above-mentioned provision of electronic devices.
  • the device includes an electronic device, and the electronic device uses the above-mentioned polymer film.
  • Polymer films have both good thermodynamic and optical properties and can be used as various devices or devices in electronic equipment (including antennas, circuit boards, light-emitting devices, displays, etc.) display device, etc.) substrate, covering film or protective film, touch screen panel, transparent substrate for under-screen camera, etc.
  • This application also provides a device for preparing the polymer film described in the fourth, fifth or sixth aspect of the embodiments of this application.
  • Figure 1 is a schematic structural diagram of an electronic device 100 provided by an embodiment of the present application.
  • Figure 2 is a schematic structural diagram of a flexible OLED light-emitting device 100a provided by an embodiment of the present application
  • Figure 3 is a schematic structural diagram of the device 200 provided by the embodiment of the present application.
  • Figure 4 is a dynamic thermomechanical analysis (DMA) curve graph of the polyimide film of Example 1 and Example 2;
  • FIG. 5 is a thermogravimetric analysis (TGA) curve graph of the polyimide film of Example 1 and Example 2;
  • Figure 6 shows the UV-visible absorption curves of the polyimide films of Example 1 and Example 2.
  • the polyimide film as the base material is mixed with other Mismatch in thermal expansion of materials will cause problems such as peeling, cracking, and warping.
  • flexible displays for mobile phones generally use top-emission flexible OLED devices (AMOLED).
  • AMOLED top-emission flexible OLED devices
  • the light is emitted from the cathode.
  • the LTPS (low-temperature polysilicon) TFT backplane does not require light to pass through, so a yellow polyimide slurry coating film is used. It can be used as a substrate.
  • under-screen cameras that is, the camera is placed under the display
  • external light needs to pass through the LTPS (low-temperature polysilicon) TFT backplane film so that the camera can capture the light, so high-temperature film must be used.
  • the light transmittance is achieved by flexible polyimide.
  • polyamic acid polymerized by using specific monomers The polyamic acid is used as a precursor for preparing polyimide and is prepared by combining a specific process.
  • Polyimide film can have both good thermodynamic properties and good optical properties. Specifically, the polyimide film has excellent heat resistance (Tg ⁇ 400°C) and ultra-low thermal expansion coefficient CTE ( ⁇ 10ppm/K) , excellent mechanical properties, good light transmittance and low yellowness (YI) value, which can meet the application needs of flexible electronic components in displays, and are expected to be used in electronic devices such as device substrates, cover films, touch screen panels, and under-screen cameras. It is applied in scenarios such as using transparent substrates.
  • embodiments of the present application provide a polyamic acid that includes repeating units derived from aromatic dianhydrides and aromatic diamines, and the aromatic dianhydrides and/or aromatic diamines on the aromatic ring. At least one carbon atom is connected to a fluorine atom through a C-F single bond. Wherein, at least one carbon atom on the aromatic ring in the aromatic dianhydride and/or aromatic diamine is connected to a fluorine atom through a C-F single bond means that at least one carbon atom constituting the above-mentioned aromatic ring is directly connected to a fluorine atom, Fluorine atoms form C-F single bonds with the carbon atoms constituting the aromatic ring.
  • the aromatic ring is a benzene ring, and at least one carbon atom on the benzene ring is directly connected to a fluorine atom, that is, the substituent on the carbon position is a fluorine atom.
  • the polyamic acid provided in the embodiment of the present application is a precursor material for preparing polyimide.
  • the polyamic acid includes repeating units derived from aromatic dianhydrides and aromatic diamines. That is, the polyamic acid adopts aromatic compounds with aromatic structures.
  • the dianhydride and aromatic diamine are copolymerized.
  • aromatic monomers is beneficial to the polyimide film to obtain good thermodynamic properties, and the aromatic monomers are conducive to inhibiting the accumulation of molecular chains and giving the polyimide good transparency.
  • aromatic dianhydrides and/or At least one carbon atom on the aromatic ring in the aromatic diamine is connected to a fluorine atom through a CF single bond, which can reduce the formation of charge transfer complexes (CTC) and can make polyimide through a specific film forming process.
  • CTC charge transfer complexes
  • the molecular chains are partially cross-linked through CF single bonds, thereby further improving the thermodynamic properties of polyimide (including heat resistance and dimensional stability, etc.), while also having good optical properties (including high light transmittance, low yellowness) index, etc.).
  • At least one carbon atom on the aromatic ring in the aromatic dianhydride and/or aromatic diamine is connected to a fluorine atom through a C-F single bond, that is, the C-F single bond can be introduced through the aromatic dianhydride monomer. , it can also be introduced by aromatic diamine monomer, or it can be introduced by aromatic dianhydride monomer and aromatic diamine monomer. Among them, the aromatic dianhydride and/or aromatic diamine can introduce one C-F single bond through one carbon atom on the aromatic ring, or can introduce multiple C-F single bonds through multiple carbon atoms on the aromatic ring.
  • At least one carbon atom on the aromatic ring of the aromatic diamine is connected to a fluorine atom through a C-F single bond.
  • the structure of the aromatic diamine can be as shown in the general formula (1):
  • R in the general formula (1) represents an aromatic group with 1 to 10 benzene rings, and at least one carbon atom on part or all of the benzene rings in R is connected to a fluorine atom through a C-F single bond, and there is no fluorine atom on the benzene ring.
  • a hydrogen atom, alkyl group, fluoroalkyl group or phenyl group is connected to the carbon position to which the fluorine atom is connected.
  • Fluorine-containing aromatic diamine monomers with the structure of general formula (1) are used as raw materials for the preparation of polyimide precursors, which can effectively reduce the formation of charge transfer complexes (CTC), and after specific process treatment, the polyimide Amine can partially cross-link the molecular chain through C-F single bonds, thereby effectively improving the transparency of the polyimide film and giving the polyimide film excellent thermodynamic properties such as high glass transition temperature, high thermal weight loss temperature, and low thermal expansion coefficient.
  • CTC charge transfer complexes
  • R can specifically be a substituted benzene ring with one benzene ring, or a substituted biphenyl structure with two or more benzene rings, etc.
  • the substituted biphenyl structure can specifically be a substituted diphenyl structure, substituted biphenyl structure, etc. terphenyl structure, substituted tetraphenyl structure, etc.
  • R is a substituted benzene ring.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-A1) or (1-A2),
  • a is an integer from 1 to 4.
  • a can be 1, 2, 3, 4, that is, the benzene ring can be connected with 1, 2, 3 or 4 fluorine atoms;
  • b 4-a, b is an integer from 0 to 3, specifically 0, 1, 2, or 3;
  • R 1 is a group connected to the carbon position of the benzene ring that is not connected to a fluorine atom group, R 1 can be a hydrogen atom, an alkyl group, a fluoroalkyl group or a phenyl group.
  • R is a substituted diphenyl structure.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-B),
  • c on the two benzene rings are independently integers from 1 to 4.
  • c can be 1, 2, 3, or 4, that is, each benzene ring can be connected through a CF single bond.
  • 1, 2, 3 or 4 fluorine atoms the number of fluorine atoms connected to the two benzene rings can be the same or different;
  • d 4-c, d is an integer from 0 to 3, specifically 0, 1, 2, or 3;
  • R 2 is a group connected to the carbon position of the benzene ring that is not connected to a fluorine atom.
  • R 2 on the two benzene rings can be independently a hydrogen atom, an alkyl group, or a fluoroalkyl group. group or phenyl; the number of R 2 connected to the two benzene rings can be the same or different; the R 2 on the two benzene rings can be the same group or different groups.
  • R is a substituted terphenyl structure.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-C),
  • R is a substituted tetraphenyl structure.
  • the general structural formula (1) of the aromatic diamine can be expressed as (1-D),
  • e on the four benzene rings are independently integers from 1 to 4.
  • e can be 1, 2, 3, or 4, that is, each benzene ring can be connected through a CF single bond.
  • 1, 2, 3 or 4 fluorine atoms the number of fluorine atoms connected to the four benzene rings can be the same or different;
  • R 4 is a group connected to the carbon position of the benzene ring that is not connected to a fluorine atom.
  • R 4 on the four benzene rings can be independently a hydrogen atom, an alkyl group, or a fluoroalkyl group. group or phenyl; the number of R 4 connected to the four benzene rings can be the same or different; the R 4 on the four benzene rings can be the same group or different groups.
  • the alkyl group in the molecular structure of the above-mentioned aromatic diamine, can be an unsubstituted alkyl group with 1 to 10 carbon atoms. Specifically, it can be methyl, ethyl, n-propyl, or isopropyl. , n-butyl, isobutyl, tert-butyl, pentyl, etc.
  • the fluoroalkyl group can be a fluorine-substituted alkyl group with 1 to 10 carbon atoms.
  • the fluoroalkyl group can be a partially fluorine-substituted or perfluoro-substituted alkyl group.
  • it can be a fluoromethyl (such as trifluoromethyl). , fluoroethyl, fluoro-n-propyl, fluoro-isopropyl, fluoro-n-butyl, fluoro-isobutyl, fluoro-tert-butyl, fluoropentyl, etc.
  • the aromatic diamine may be any one or more selected from formulas (1-1) to (1-12):
  • the aromatic diamine monomer may include one or more types, specifically, it may include any one or more types of (1-1) to (1-12).
  • the above-mentioned aromatic diamine monomers in the embodiments of the present application are easy to obtain and have good rigidity, which is conducive to imparting good transparency and thermal properties to the polyimide.
  • the aromatic dianhydride when the carbon atom on the aromatic ring of the aromatic diamine has a fluorine atom introduced through a CF single bond, the aromatic dianhydride can be selected from formulas (2-1) to (2-17) any one or more of:
  • the rigid non-planar structure of the aromatic dianhydride in the embodiment of the present application can effectively inhibit the accumulation of polymer molecular chains and give the polyimide good transparency and thermal properties.
  • the aromatic dianhydride monomer may include one or more types, specifically, it may include any one or more types of (2-1) to (2-17).
  • the molar proportion of structural units derived from aromatic dianhydride is 50% to 100%. That is, in the molecular structure of polyamic acid, the structural units derived from the dianhydride may all be derived from the above-mentioned aromatic dianhydride. In this case, the molar ratio of the structural units derived from the aromatic dianhydride is 100%; it may also be a part of it. Derived from the above-mentioned aromatic dianhydride, at this time, the molar proportion of structural units derived from aromatic dianhydride is greater than or equal to 50% and less than 100%.
  • the molar proportion of structural units derived from aromatic dianhydride Ratios can be 50%, 60%, 70%, 80%, 90%, 95%, etc. Controlling the molar proportion of structural units derived from aromatic dianhydrides at a higher proportion is beneficial to improving the thermodynamic properties of polyimide films.
  • an appropriate amount of a dianhydride monomer with a rigid alicyclic structure can be introduced during the preparation process of the polyamic acid, that is, an aromatic dianhydride can be used at the same time.
  • a dianhydride monomer with a rigid alicyclic structure Two types of monomers, dianhydrides with rigid alicyclic structures, are copolymerized with aromatic diamines.
  • the polyamic acid further includes repeating units derived from the dianhydride of a rigid alicyclic structure and the above-mentioned aromatic diamine.
  • the conjugated structure on the original aromatic polyimide segment can be destroyed, the interaction between molecular chains can be weakened, and the charge transfer complex can be weakened or even eliminated ( CTC) effect thereby improves the light transmittance of the polyimide film and increases the distance between molecular chains, which helps to improve the solubility of the polyimide.
  • CTC charge transfer complex
  • the molar proportion of the structural units derived from the dianhydride of the rigid alicyclic structure is 5% to 50%.
  • the molar proportion of the structural units derived from the aromatic dianhydride may be 5%, 8%, 10%, 15%, 20%, 30%, 40%, 50%, etc.
  • the molar proportion of the structural units derived from the dianhydride of the rigid alicyclic structure is 5% to 15%. Controlling the amount of the dianhydride monomer with a rigid alicyclic structure to a smaller amount is beneficial to obtaining better thermodynamic properties while improving the optical properties of the polyimide film.
  • the dianhydride with a rigid alicyclic structure includes any one or more of the formulas (3-1) to (3-4):
  • polyamic acid is polymerized by one or more aromatic dianhydride monomers and one or more aromatic diamine monomers.
  • the monomers have a fully aromatic structure.
  • the polyamic acid Only repeating units derived from aromatic dianhydrides and aromatic diamines are included.
  • polyamic acid is polymerized by one or more aromatic dianhydride monomers, one or more dianhydrides with a rigid alicyclic structure, and one or more aromatic diamine monomers. , at this time polyamic acid includes derivatives derived from aromatic
  • the repeating units of aromatic dianhydrides and aromatic diamines also include repeating units of dianhydrides and aromatic diamines derived from rigid alicyclic structures.
  • the polyamic acid includes repeating units derived from the aromatic dianhydride represented by the formula (2-3) and the aromatic diamine represented by the formula (1-8).
  • the four carbon atoms on the aromatic ring in the aromatic diamine shown are connected to four fluorine atoms through C-F single bonds; 1 represents the number of repetitions of the repeating unit, that is, the degree of polymerization, in order to make the polymer have better film-forming properties and mechanical properties, 1 may be an integer greater than or equal to 10, specifically, it may be an integer from 10 to 100 or 15 to 100.
  • the polyamic acid includes a first repeating unit derived from the aromatic dianhydride represented by the formula (2-3) and the aromatic diamine represented by the formula (1-8), and a first repeating unit derived from the aromatic dianhydride represented by the formula (1-8), and The second repeating unit of the dianhydride of the rigid alicyclic structure shown in 3-1) and the aromatic diamine shown in the formula (1-8);
  • the embodiments of the present application accordingly provide a polyamic acid solution, which includes the polyamic acid and an organic solvent described in the embodiments of the present application.
  • the solid content of the polyamic acid solution may be 5%-50%. That is, in the polyamic acid solution, the mass content of polyamic acid can be 5%-50%; in some embodiments, the mass content of polyamic acid can be 10%-35%; in some embodiments, the mass content of polyamic acid The content can be 15%-25%.
  • Polyamic acid has a suitable solid content, which is conducive to obtaining a polyimide film with suitable thickness and good comprehensive properties through the film-forming process.
  • other components such as fillers, etc., can also be added to the polyamic acid solution according to actual application needs.
  • the filler may specifically be an inorganic filler.
  • the organic solvent may include N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), ⁇ -butyrolactone (GBL), N-methyl One or more of pyrrolidone (NMP) and m-cresol (m-Cresol).
  • DMAc N,N-dimethylacetamide
  • DMF N,N-dimethylformamide
  • GBL ⁇ -butyrolactone
  • NMP N-methyl One or more of pyrrolidone
  • m-Cresol m-cresol
  • the embodiment of the present application also provides a polyimide film prepared from the above polyamic acid solution.
  • the polyimide film can be obtained by coating a polyamic acid solution to form a film and then imidizing the film.
  • the embodiments of the present application provide a method for preparing a polyimide film, including:
  • the polyamic acid solution provided in the embodiment of the present application is coated on the substrate. After removing the solvent, it is placed in a vacuum or protective atmosphere. Heat treatment is performed in an atmosphere to complete imidization, and a polyimide film is obtained; where the heat treatment includes rising from room temperature to 355°C-450°C through a gradient heating program or a continuous temperature rising program, and holding at 355°C-450°C for 0.05h-2h. .
  • the gradient heating program during the heat treatment process includes: rising from room temperature to 60°C-100°C for 0.5h-2h, then raising the temperature to 130°C-180°C and maintaining it for 0.5h-2h, and then raising the temperature to 230°C. °C-300°C/0.5h-2h, then heat up to 355°C-450°C.
  • the continuous temperature rise program during the heat treatment process includes: continuously heating from room temperature to 355°C-450°C at a heating rate of 1-10°C/m11.
  • the heating rate may be 1°C/m11, 2°C/m11, 3°C/m11, 4°C/m11, 5°C/m11, 6°C/m11, 7°C/m11, 8°C/m11, 9 °C/m11, 10°C/m11.
  • Appropriate heating rate control is conducive to the completion of imidization and the formation of a polyimide film with more uniform and stable properties.
  • the substrate may be a glass substrate.
  • the solvent removal operation can be carried out in an argon, nitrogen or air atmosphere, specifically it can be maintained in the above atmosphere in the range of 30-120°C for 0.1h to 8h.
  • the above-mentioned heat treatment can be performed in an oven under vacuum or a protective atmosphere, where the protective atmosphere can be a mixed atmosphere of hydrogen and argon, a mixed atmosphere of hydrogen and nitrogen, an argon atmosphere or a nitrogen atmosphere.
  • the special heat treatment process of this application can achieve partial cross-linking of polyimide molecular chains while imidizing polyamic acid, so that polyimide can obtain good optical properties and better thermodynamic properties. .
  • the heat preservation at 355°C-450°C for 0.05h-2h may specifically be at temperatures of 355°C, 360°C, 370°C, 380°C, 400°C, 410°C, 420°C, 430°C, 450°C, etc. Insulation 0.05h, 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.8h, 1h, 1.5h or 2h, etc.
  • the substrate covered with the polyimide film can be immersed in deionized water after naturally cooling to room temperature, and heated to peel off the polyimide film from the substrate to obtain the polyimide film. imine film.
  • the polyimide film includes polyimide, and the polyimide includes repeating units derived from aromatic dianhydrides and aromatic diamines. At least one carbon atom on the aromatic ring is connected to a fluorine atom through a C-F single bond; in the polyimide film, part of the polyimide is cross-linked through a C-F single bond.
  • the polyamic acid includes repeating units derived from the aromatic dianhydride represented by the formula (2-3) and the aromatic diamine represented by the formula (1-8).
  • the four carbon atoms on the aromatic ring in the aromatic diamine shown are connected to four fluorine atoms through CF single bonds;
  • m represents the number of repetitions of the repeating unit, that is, the degree of polymerization, in order to make the polymer have better film-forming properties. and mechanical properties, m may be an integer greater than or equal to 10, specifically, it may be an integer from 10 to 100 or 15 to 100.
  • part of the polyimide is cross-linked through CF single bonds, that is, in the polyimide film, part of the polyimide may exist in a cross-linked manner as shown in the following formula (IIb).
  • m 1 and m 2 represent the number of repetitions of the repeating unit.
  • the thickness of the polyimide film can be 2 ⁇ m to 100 ⁇ m; in some embodiments, the thickness of the polyimide film is 5 ⁇ m to 450 ⁇ m; in some embodiments, the thickness of the polyimide film is 20 ⁇ m to 450 ⁇ m; the implementation of this application In this method, the thickness of the polyimide film may be, for example, 2 ⁇ m, 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, or 100 ⁇ m.
  • the polyimide film in the embodiment of the present application has good optical properties and good thermodynamic properties. Specifically, the average transmittance of the polyimide film in the range of 4001m-7801m (visible light region) is ⁇ 75%; some implementations In some embodiments, the average light transmittance of the polyimide film in the range of 4001m-7801m is ⁇ 78%; in some embodiments, the average light transmittance of the polyimide film in the range of 4001m-7801m is ⁇ 80%.
  • the yellowness value (YI) of polyimide film based on ASTM E313 standard is ⁇ 15. The yellow index (YI) is used to characterize the degree of yellowing (yellowing) of colorless, transparent, translucent or nearly white polymer materials.
  • the polyimide film has a yellowness value (YI) of ⁇ 10 based on ASTM E313 standard.
  • the b value of the polyimide film in the embodiment of the present application under D65 light source is less than 10, and the haze is less than 1%.
  • the glass transition temperature (Tg) of the polyimide film in the embodiments of the present application is ⁇ 400°C; in some embodiments, the glass transition temperature (Tg) of the polyimide film is ⁇ 420°C.
  • the polyimide film in the embodiments of the present application has a thermal expansion coefficient (CTE) in the range of 40°C to 4400°C ⁇ 10 ppm/K; in some embodiments, the polyimide film has a thermal expansion coefficient (CTE) in the range of 40°C to 4400°C. -10ppm/K to 10ppm/K.
  • CTE thermal expansion coefficient
  • the 1% thermogravimetric loss temperature (Td 1% ) of the polyimide film in the embodiments of the present application under nitrogen is >500°C; in some embodiments, the 1% thermogravimetric loss temperature of the polyimide film under nitrogen (Td 1%) Td 1% ) ⁇ 520°C; in some embodiments, the 1% thermogravimetric loss temperature (Td 1 %) of the polyimide film under nitrogen is ⁇ 550°C; in some embodiments, the polyimide film under nitrogen The 1% thermogravimetric loss temperature (Td 1% ) ⁇ 580°C.
  • the polyimide film in the embodiment of the present application also has excellent mechanical properties.
  • the tensile strength of the polyimide film in the embodiment of the present application is greater than 120MPa, the elastic modulus is greater than or equal to 5GPa, and the elongation at break is greater than or equal to 5 %.
  • the polyimide film of the embodiment of the present application can meet the application requirements of flexible electronic components in display screens, and can be used in device substrates, covering films or protective films, touch screen panels, transparent substrates for under-screen cameras in electronic equipment, etc. It can be used in flexible display substrates or protective films.
  • the embodiments of this application also provide the application of the above-mentioned polyimide film in the preparation of flexible substrates, communication equipment insulation materials, electronic equipment insulation materials, motor insulation materials, and electrical insulation materials.
  • an embodiment of the present application also provides an electronic device 100.
  • the electronic device 100 may be a flexible device.
  • the electronic device 100 includes a substrate 10 and a functional layer 20 disposed on the substrate 10.
  • the substrate 10 includes an electronic device 100 according to the present application.
  • the above-mentioned polyimide film For example, the above-mentioned polyimide film.
  • the electronic device 100 can be any type of device that requires the use of a polyimide film as a substrate or cover.
  • the device may include, for example, a transparent antenna, a flexible circuit board, a light emitting device, a display device, a lighting device, a solar cell, etc.
  • Different functional layers 20 may be provided on the substrate 10 for different electronic devices.
  • the functional layer 20 of the transparent antenna may include a conductive layer, etc.
  • the functional layer 20 of the flexible circuit board may include a conductive layer, etc.
  • the functional layer 20 of the light-emitting device may include a light-emitting layer, etc.
  • the functional layer 20 of the solar cell may be Including light-absorbing layer, etc.
  • the functional layers of the flexible OLED light-emitting device 100a may include a thin film transistor layer (TFT layer) 201, a light-emitting layer 202, and a touch layer formed sequentially on the polyimide film 10.
  • TFT layer thin film transistor layer
  • Layer 203, polarizer layer 204, optical glue layer 205, cover plate 206 can be polyimide or UTG glass, etc.).
  • the preparation process may include coating the polyamic acid solution provided in the embodiment of the present application on a glass substrate, forming a polyimide film through heat treatment, and then preparing the above-mentioned OLED light-emitting device functional layer on the polyimide film, Then peel off the glass substrate to obtain a flexible OLED light-emitting device.
  • the cover plate 206 can also be made of the polyimide film in the embodiment of the present application.
  • an embodiment of the present application further provides a device 200.
  • the device 200 may be an electronic device or a communication device.
  • the device 200 includes the polyimide film described in the embodiment of the present application.
  • the device 200 may be a mobile phone, a tablet computer, a notebook computer, a portable computer, a wearable device, a television, a video recorder, a camcorder, a radio, a cassette player, etc.
  • the polyimide film may be used as a substrate for a transparent antenna, a flexible circuit board, a light emitting device, a display device, etc. in the device 200 .
  • the device 200 is a mobile phone.
  • the mobile phone includes a display screen 201.
  • the display screen 201 includes a flexible OLED light-emitting device 100a.
  • the flexible OLED light-emitting device 100a uses a polyimide film as a substrate.
  • the embodiments of the present application also provide a device for preparing the polyimide film described in the embodiments of the present application.
  • This device can realize the preparation of the above-mentioned polyimide film in the embodiment of the present application, and the device can include a coating component, a heat treatment component, etc.
  • At least one of the following or similar expressions thereof refers to any combination of these items, including any combination of a single item (items) or a plurality of items (items).
  • at least one of a, b, or c or “at least one of a, b, and c” can mean: a, b, c, a-b ( That is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.
  • step (1) React 1,4-dicarboxytetrafluorobenzene with tetrabutylammonium bromide Bu 4 NBr to obtain 1,4-dibromotetrafluorobenzene; add 1,4-dibromotetrafluorobenzene into a three-necked bottle , add p-aminophenylboronic acid and catalyst tetrakis (triphenylphosphorus) palladium, then add THF and 2M potassium carbonate aqueous solution, vacuum and vent nitrogen, raise the temperature to 80°C to start the reaction, react for 18 hours, and purify on a silica gel column to obtain the above formula ( Aromatic diamine monomer TP4F shown in 1-8).
  • the reaction process of step (1) is as follows:
  • the heat treatment operation is specifically to raise the temperature from room temperature to 400°C-410°C at a heating rate of 3°C/m11 and maintain it for 10-20m11. After heat treatment, cool to room temperature and then soak in The film was removed in hot water to obtain a high-performance polyimide film with a film thickness of 10 ⁇ 1 ⁇ m.
  • the reaction process of step (2) is as follows:
  • Table 1 shows the elemental analysis results of the polymer film before and after heat treatment in Example 1. It is a polyamic acid film before heat treatment and a polyimide film after heat treatment.
  • the thermal expansion coefficient CTE of the polyimide film was obtained through thermomechanical analysis (TMA) testing; the glass transition temperature Tg of the film was obtained through dynamic thermomechanical analysis (DMA) testing; the polyimide film was obtained through thermogravimetric analysis (TGA) testing.
  • TMA thermomechanical analysis
  • DMA dynamic thermomechanical analysis
  • TGA thermogravimetric analysis
  • the 1% thermal weight loss temperature Td 1% of the amine film; and the average transmittance of the polyimide film in the range of 400-7801m was tested by a UV-visible absorption spectrometer, and its yellowness index YI value was tested based on the ASTM E313 standard Test, the tensile modulus, tensile strength, and elongation at break of the polyimide film are tested through tensile tests.
  • tensile modulus refers to the elasticity of the material when stretched, and its value is the ratio of the force required to stretch the material per unit length along the central axis to its cross-sectional area.
  • Tensile strength refers to the stress that produces the maximum uniform plastic deformation of a material. In a tensile test, the maximum tensile stress experienced by the sample until it breaks is the tensile strength. Elongation at break is the ratio of the displacement value of the sample at break to its original length.
  • the thermal expansion coefficient CTE of the polyimide film obtained in Example 1 of the present application is about -8ppm/K in the range of 404400°C, Tg>430°C, Td 1% >550°C, tensile modulus>8GPa, tensile modulus
  • the tensile strength is >280MPa
  • the average transmittance in the visible light region is >78%
  • the yellowness index YI value based on the ASTM E313 standard is less than 10.
  • the comprehensive performance of the polyimide film in Example 1 of the present application is very outstanding, with excellent optical properties, thermodynamic properties and mechanical mechanical properties, especially high Tg, Td 1% and ultra-low CTE, so that it can not only meet the requirements of transparency It can also meet performance requirements such as high heat resistance, high dimensional stability, high strength, and high flexibility.
  • the polyimide film in Example 1 of the present application has the above-mentioned excellent properties, mainly because the fully aromatic rigid chain structure makes the polyimide itself excellent in heat resistance and mechanical properties, and the introduction of CF bonds in the diamine monomer is weakened.
  • the electron-donating ability of the diamine monomer weakens the CTC effect (charge transfer complex) and improves the optical properties; and under the action of a specific heat treatment process, the polyimide is partially cross-linked during the film forming process, making the polyimide The thermal expansion coefficient CTE of the amine film is further reduced, thereby finally obtaining a flexible polyimide film with excellent thermodynamic properties, optical properties and mechanical mechanical properties.
  • the specific heat treatment operation is to raise the temperature from room temperature to 400°C-410°C at a heating rate of 3°C/m11, and maintain 10-20m11, after heat treatment, cool to room temperature and then soak in hot water to remove the film, to obtain a colorless and transparent polyimide film with a film thickness of 10 ⁇ 1 ⁇ m.
  • the above reaction process is as follows:
  • x is 0.7 and y is 0.3.
  • Example 2 of the present application has a thermal expansion coefficient CTE of about 6.2ppm/K in the range of 404 to 400°C, Tg > 430°C, Td 1% > 500°C, tensile modulus > 5GPa, and tensile modulus > 5GPa.
  • the tensile strength is >150MPa
  • the average transmittance in the visible light region is >80%
  • the yellowness index YI value based on the ASTM E313 standard is less than 10.
  • the comprehensive performance of the polyimide film in Example 2 of the present application is very outstanding, with excellent optical properties, thermodynamic properties and mechanical mechanical properties, especially high Tg, Td 1% and ultra-low CTE, so that it can not only meet the requirements of transparency It can also meet performance requirements such as high heat resistance, high dimensional stability, high strength, and high flexibility.
  • the polyimide film in Example 2 of the present application has the above-mentioned excellent properties, mainly due to the fully aromatic rigid chain structure, which makes the polyimide itself excellent in heat resistance and mechanical properties, and the introduction of CF bonds in the diamine monomer.
  • Example 2 of the present application also introduces the large-volume twisted structure comonomer 9,9-bis(3 , 4-dicarboxyphenyl) fluorene dianhydride, destroys the orderly stacking of molecular chains, weakens the interaction between molecular chains, and further improves the optical properties; and under the action of a specific heat treatment process, the polyimide film during the film forming process The amine is partially cross-linked, further reducing the thermal expansion coefficient CTE of the polyimide film, thereby ultimately obtaining a flexible polyimide film with excellent thermodynamic properties, optical properties and mechanical mechanical properties.
  • Figure 4 is a dynamic thermomechanical analysis (DMA) curve chart of the polyimide film in Example 1 and Example 2 of the present application; from Figure 4, the glass transition temperature Tg of the polyimide film can be known, and the glass transition temperature Tg of the polyimide film in Example 1
  • the glass transition temperature Tg of the polyimide film is 437°C; the glass transition temperature Tg of the polyimide film in Example 2 is 427°C.
  • Figure 5 is a thermogravimetric analysis (TGA) curve chart of the polyimide film in Example 1 and Example 2 of the present application; from Figure 5, it can be seen that the 1% thermal weight loss temperature Td 1% of the polyimide film, Example 1 The 1% thermal weight loss temperature Td 1% of the polyimide film is 560°C; the 1% thermal weight loss temperature Td 1% of the polyimide film of Example 2 is 520°C.
  • TGA thermogravimetric analysis
  • Figure 6 is the UV-visible absorption curve of the polyimide film of Example 1 and Example 2 of the present application; from Figure 6, it can be seen that the transmittance of the polyimide film in the visible light region, the polyimide film of Example 1 The average light transmittance in the visible light region is 79%; the average light transmittance of the polyimide film of Example 2 in the visible light region is 82.5%.
  • the specific heat treatment operation is to raise the temperature from room temperature to 400°C-410°C at a heating rate of 3°C/m11 and maintain it for 10-20m11. After heat treatment, cool to room temperature and then soak in hot water to remove the film.
  • the film thickness is 10 ⁇ 1 ⁇ m high performance polyimide film.
  • the thermal expansion coefficient CTE of the polyimide film obtained in Example 3 of the present application is about -8ppm/K in the range of 404400°C, Tg>430°C, Td 1% >550°C, and the average transmittance in the visible light region> 75%, yellowness index YI value based on ASTM E313 standard is less than 15.
  • the polyimide film in Example 3 of the present application has outstanding comprehensive properties, including excellent optical properties and thermodynamic properties, especially high Tg, Td 1% and ultra-low CTE, thereby not only meeting the requirements for transparency, but also meeting High heat resistance, high dimensional stability, high strength, high flexibility and other performance requirements.
  • the polyimide film in Example 3 of the present application has the above-mentioned excellent properties, mainly because the fully aromatic rigid chain structure makes the polyimide itself excellent in heat resistance and mechanical properties, and the introduction of CF bonds in the diamine monomer is weakened.
  • the electron-donating ability of the diamine monomer weakens the CTC effect (charge transfer complex) and improves the optical properties; and under the action of a specific heat treatment process, the polyimide is partially cross-linked during the film forming process, making the polyimide
  • the thermal expansion coefficient CTE of the amine film is further reduced, thereby finally obtaining a flexible polyimide film with excellent thermodynamic properties and optical properties.
  • x is 0.9 and y is 0.1.
  • Example 4 of the present application has a thermal expansion coefficient CTE of about 10 ppm/K in the range of 404 to 400°C, Tg ⁇ 430°C, Td 1% > 500°C, tensile modulus ⁇ 5GPa, and tensile modulus ⁇ 5GPa.
  • Intensity ⁇ 150MPa, and the average transmittance in the visible light region is >80%, and the yellowness index YI value based on the ASTM E313 standard is less than 10.
  • the polyimide film in Example 4 of the present application has outstanding comprehensive properties, including excellent optical properties and thermodynamic properties, especially high Tg, Td 1% and ultra-low CTE, thereby not only meeting the requirements for transparency, but also meeting High heat resistance, high dimensional stability, high strength, high flexibility and other performance requirements.
  • the polyimide film in Example 4 of the present application has the above-mentioned excellent properties, mainly due to the aromatic rigid chain structure and rigid alicyclic structure monomers which make the polyimide itself have excellent heat resistance and mechanical properties.
  • the introduction of CF bonds weakens the electron-donating ability of the diamine monomer, weakens the CTC effect (charge transfer complex), and improves the optical properties; and under the action of a specific heat treatment process, partial cross-polymerization occurs in the polyimide during the film forming process.
  • the combination further reduces the thermal expansion coefficient CTE of the polyimide film, thereby finally obtaining a flexible polyimide film with excellent thermodynamic properties and optical properties.
  • the solution is diluted to a solid content of 10%, filtered to remove insoluble impurities, vacuumed to remove bubbles, then scraped onto a glass plate, placed on a horizontal heating table, heated to 80°C and pre-baked for 120m11 to obtain a pre-dried polyamic acid film.
  • the glass plate is transferred to the reduction furnace (the built-in atmosphere is a mixture of hydrogen and nitrogen) and is heated in a certain program (80°C for 1 hour ⁇ 150°C for 1 hour ⁇ 250°C for 2 hours ⁇ 350°C for 0.5 hours), cooled to room temperature and then immersed in heat
  • the film was removed in water to obtain a polyimide film with a film thickness of 10 ⁇ 1 ⁇ m.
  • the polyimide films prepared in Examples 1 to 4 of the present application have better overall properties than the polyimide films of Comparative Examples 1-4, especially in the implementation of the present application.
  • the polyimide film of this example not only has high transmittance in the visible light region, but also has a high glass transition temperature Tg, a high thermal weight loss temperature Td 1% and a low thermal expansion coefficient CTE, that is, it has both high heat resistance and high dimensional stability.
  • the properties and good optical properties can better meet the application requirements of transparent substrates with high transparency, high heat resistance and high dimensional stability in electronic devices.
  • polyimides in Examples 1-4 of the present application use aromatic dianhydrides with aromatic structures and aromatic diamines (fully aromatic structural monomers) for copolymerization, or use aromatic dianhydrides with aromatic structures
  • the dianhydride with a rigid alicyclic structure is obtained by copolymerizing an aromatic diamine (aromatic and alicyclic monomer), and the aromatic ring carbon position of the aromatic diamine is connected to a fluorine atom through a CF single bond.
  • aromatic and alicyclic structural monomers are used.
  • the carbon atoms on the aromatic ring in the diamine are connected to fluorine atoms through CF single bonds, which can reduce the formation of charge transfer complexes (CTC), and can allow the polyimide molecular chain to pass through a specific heat treatment film-forming process.
  • CTC charge transfer complexes
  • Example 1 it can be seen from comparing Example 1 and Comparative Example 2 that although Comparative Example 2 uses the same monomer as Example 1 to prepare the polyimide film, the glass transition temperature of the polyimide film in Comparative Example 2 is Both Tg and high thermal weight loss temperature Td 1% are lower than that of Example 1.
  • the thermal expansion coefficient CTE of the polyimide film of Comparative Example 2 is much higher than that of Example 1. This is because the heat treatment process of Comparative Example 2 is different from that of Example 1.
  • the polyimide molecules are partially cross-linked by using a specific heat treatment process, thereby further improving the thermodynamic properties of the polyimide film and further reducing the thermal expansion coefficient CTE of the polyimide film.

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Abstract

聚合物前驱体包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，采用特定工艺制备成聚合物薄膜，可使聚合物薄膜兼具良好热力学性能和良好光学性能，满足电子设备中柔性电子元器件的应用需求。

Description

聚合物前驱体、聚合物薄膜及其制备方法
本申请要求于2022年5月31日提交中国专利局、申请号为202210612628.1、申请名称为“聚合物前驱体、聚合物薄膜及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及聚合物薄膜制备技术领域，特别是涉及一种聚合物前驱体、聚合物薄膜及其制备方法。
背景技术
随着消费电子行业的迅速发展，显示产品不断向轻量化、柔性化和小型化方向发展。为满足显示产品轻量化、柔性化需求，采用具有柔性的透明高分子材料代替传统玻璃基底制备成各种各样的电子元器件(如薄膜晶体管或透明电极等)是目前行业内的重点研究方向。在诸多透明高分子材料中，透明聚酰亚胺相对具有优异热稳定性、高玻璃化转变温度Tg、高机械强度和较低的热膨胀系数CTE等性能，是最有希望替代玻璃基底实现电子元器件轻质柔性化的备选材料。
然而上述电子元器件制备过程中必须经过高温工艺，如低温多晶硅(LTPS)工艺制造有机发光二极管(OLED)装置过程中具有接近500℃的工艺温度。而目前已有透明聚酰亚胺材料难以满足上述高温制程，有一些芳香聚酰亚胺材料虽然可以耐受短时500℃以上的高温，但此类芳香聚酰亚胺黄度指数很高(15μm厚度的黄度指数YI高达46.0))，可见光区透光率低(<60％)，也就是说，目前已有聚酰亚胺材料难以同时兼顾高耐热、高透明的性能要求，限制了其在显示产品中的应用，从而也限制了真正意义上的采用屏下摄像头方案的全面屏的制造，因此，有必要从分子结构设计到聚合物及薄膜制备工艺优化角度开发新型耐高温透明聚酰亚胺材料。
发明内容
鉴于此，本申请实施例提供一种聚合物前驱体、聚合物薄膜及其制备方法，通过对聚酰亚胺的前驱体聚酰胺酸进行特殊结构设计，并采用特定工艺制备成聚酰亚胺薄膜，该聚酰亚胺薄膜兼具良好热力学性能和良好光学性能，可满足显示领域中柔性电子元器件的应用需求。
具体地，本申请实施例第一方面提供一种聚合物前驱体，所述聚合物前驱体为聚酰胺酸，所述聚合物前驱体包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。
本申请实施例提供的聚酰胺酸为制备聚酰亚胺的前驱体材料，聚酰胺酸包括衍生自芳香族二酐和芳香族二胺的重复单元，即聚酰胺酸采用具有芳香结构的芳香族二酐和芳香族二胺进行共聚，采用芳香结构的单体有利于聚酰亚胺薄膜获得良好热力学性能；另外，芳香族二酐和/或芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，这样可通过特定的薄膜成型工艺使得聚酰亚胺分子链通过C-F单键发生部分交联，从而进一步提升聚酰亚胺的热力学性能(包括热稳定性和尺寸稳定性等)，同时兼具良好的光学性能(包括高透光 率、低黄度指数等)。
本申请实施方式中，所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，所述芳香族二胺的结构如通式(1)所示：
H2N-R-NH2通式(1)，
其中，R表示具有1-10个苯环的芳香基团，且R中部分或全部所述苯环上的至少一个碳原子通过C-F单键连接有氟原子，所述苯环上未连接有氟原子的碳位上连接氢原子、烷基、氟代烷基或苯基。具有通式(1)结构的含氟芳香族二胺单体作为聚酰亚胺前驱体的制备原料，可以有效降低电荷转移络合物(CTC)的形成，且经由特定工艺处理后聚酰亚胺可以通过C-F单键发生分子链部分交联，从而有效改善聚酰亚胺薄膜的透明性，同时赋予聚酰亚胺薄膜高玻璃化转变温度、高热失重温度、低热膨胀系数等优异热力学性能。
其中，R具体可以是具有1个苯环的取代苯环、也可以是具有2个或2个以上苯环的取代联苯结构等，取代联苯结构具体可以是取代的二联苯结构、取代的三联苯结构、取代的四联苯结构等。
一些实施例中，R为取代苯环，此时，芳香族二胺的结构通式(1)可以表示为(1-A1)或(1-A2)，
式(1-A1)和式(1-A2)中，a为1至4的整数；b＝4-a，b为0至3的整数；R1是苯环上未连接有氟原子的碳位上连接的基团，R1可以是氢原子、烷基、氟代烷基或苯基。
一些实施例中，R为取代的二联苯结构，此时，芳香族二胺的结构通式(1)可以表示为(1-B)，
式(1-B)中，两个苯环上的c分别独立地为1至4的整数；d＝4-c，d为0至3的整数；R2是苯环上未连接有氟原子的碳位上连接的基团，两个苯环上的R2可以是分别独立地为氢原子、烷基、氟代烷基或苯基。
一些实施例中，R为取代的三联苯结构，此时，芳香族二胺的结构通式(1)可以表示为(1-C)，
式(1-C)中，三个苯环上的e分别独立地为1至4的整数；f＝4-e，f为0至3的整数；R3是苯环上未连接有氟原子的碳位上连接的基团，三个苯环上的R3可以是分别独立地为氢原子、烷 基、氟代烷基或苯基。
一些实施例中，R为取代的四联苯结构，此时，芳香族二胺的结构通式(1)可以表示为(1-D)，
式(1-D)中，四个苯环上的e分别独立地为1至4的整数；f＝4-e，f为0至3的整数，具体为0、1、2、或3；R4是苯环上未连接有氟原子的碳位上连接的基团，四个苯环上的R4可以是分别独立地为氢原子、烷基、氟代烷基或苯基。
本申请实施方式中，所述芳香族二胺选自式(1-1)至(1-12)中的任意一种或多种：
本申请实施例上述芳香族二胺单体易得，且具有刚性非平面结构，有利于赋予聚酰亚胺良好的透明性及热性能。
本申请实施方式中，所述芳香族二酐选自式(2-1)至(2-17)中的任意一种或多种：

本申请实施例芳香族二酐的刚性非平面结构可以有效抑制聚合物分子链的堆积，赋予聚酰亚胺良好的透明性及热性能。
本申请实施方式中，以衍生自二酐的全部结构单元为100mol％计，衍生自所述芳香族二酐的结构单元的摩尔占比为50％至100％。衍生自芳香族二酐的结构单元的摩尔占比控制在较高占比有利于提升聚酰亚胺薄膜的热力学性能。
本申请实施方式中，所述聚酰胺酸还包括衍生自刚性脂环结构的二酐和所述芳香族二胺的重复单元。通过向聚酰亚胺结构中引入非芳香的刚性脂环结构，可以破坏原芳香族聚酰亚胺链段上的共轭结构，减弱分子链间的相互作用，减弱甚至消除电荷转移络合物(CTC)效应从而改善聚酰亚胺薄膜的透光率，同时增大分子链间的距离，有助于改善聚酰亚胺的溶解性。
本申请实施方式中，以衍生自二酐的全部结构单元为100mol％计，衍生自所述刚性脂环结构的二酐的结构单元的摩尔占比为5％至50％。将刚性脂环结构的二酐单体的量控制在较小量，有利于在改善聚酰亚胺薄膜光学性能的情况下，获得更优异的热力学性能。
本申请实施方式中，所述刚性脂环结构的二酐包括式(3-1)至(3-4)中的任意一种或多种：
本申请实施例第二方面提供一种前驱体溶液，即聚酰胺酸溶液，所述前驱体溶液包括本申请实施例第一方面所述的聚合物前驱体和有机溶剂。由该前驱体溶液制备的聚酰亚胺薄膜兼具良好热力学性能和光学性能。
本申请实施方式中，所述前驱体溶液的固含量为5％-50％。适合的固含量有利于通过成 膜工艺获得具有适合厚度和良好综合性能的聚酰亚胺薄膜。
本申请实施方式中，所述有机溶剂包括N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)、γ-丁内酯(GBL)、N-甲基吡咯烷酮(NMP)、间甲酚(m-Cresol)中的一种或多种。
本申请实施例第三方面提供一种聚合物薄膜的制备方法，包括：
将本申请实施例第二方面所述的前驱体溶液涂覆至基板上，经过除溶剂后，置于真空或保护气氛中进行热处理完成酰亚胺化，得到聚合物薄膜，即聚酰亚胺薄膜；
所述热处理包括由室温经梯度升温程序或连续升温程序升至355℃-450℃，在355℃-450℃保温0.05h-2h。
本申请实施方式中，所述梯度升温程序包括：由室温升至60℃-100℃保持0.5h-2h,再升温至130℃-180℃保持0.5h-2h,再升温至230℃-300℃/0.5h-2h,再升温至355℃-450℃。
本申请实施方式中，所述连续升温程序包括：由室温以1-10℃/m11的升温速率连续升温至355℃-450℃。
本申请实施例提供的聚合物薄膜的制备方法，工艺简单，易于实现工业化生产。
本申请实施例第四方面提供一种聚合物薄膜，即聚酰亚胺薄膜，所述聚酰亚胺薄膜由本申请实施例第二方面所述的前驱体溶液制备得到，或由本申请实施例第三方面所述的制备方法制备得到。该聚酰亚胺薄膜兼具良好热力学性能和光学性能。
本申请实施例第五方面提供一种聚合物薄膜，即聚酰亚胺薄膜，所述聚酰亚胺薄膜包括聚合物(即聚酰亚胺)，所述聚合物包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。
本申请实施方式中，所述聚合物薄膜中，部分所述聚合物分子通过所述C-F单键发生交联。
本申请实施例第六方面提供一种聚合物薄膜，即聚酰亚胺薄膜，所述聚酰亚胺薄膜在4001m-7801m范围内的平均透光率≥75％；基于ASTM E313标准的黄度值YI＜15；玻璃转化温度Tg≥400℃；40℃4400℃范围的热膨胀系数CTE≤10ppm/K；氮气下1％热重损失温度＞500℃。该聚酰亚胺薄膜兼具良好热力学性能和光学性能。
本申请实施方式中，所述聚合物薄膜包括聚合物，所述聚合物包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。
本申请实施方式中，聚合物薄膜的厚度为2μm4100μm。
本申请实施例提供第四方面、第五方面或第六方面所述的聚合物薄膜在制备柔性基板、通讯设备绝缘材料、电子设备绝缘材料、电机绝缘材料、电器绝缘材料中的应用。聚酰亚胺薄膜兼具良好热力学性能和光学性能，可以满足高耐热高透明需求。
本申请实施例还提供一种电子器件，所述电子器件包括本申请实施例第四方面、第五方面或第六方面所述的聚合物薄膜。聚合物薄膜可以作为电子器件的基板、绝缘间隔层、保护层、覆盖膜、盖板等。
本申请实施方式中，所述电子器件包括透明天线、柔性电路板、发光器件、显示器件、显示装置、照明器件或太阳能电池。
本申请实施例还提供一种设备，所述设备为电子设备或通讯设备，所述设备包括本申请实施例第四方面、第五方面或第六方面所述的聚合物薄膜；或包括上述提供的电子器件。具体地，所述设备包括电子器件，电子器件采用上述聚合物薄膜。聚合物薄膜兼具良好热力学性能和光学性能，在电子设备中可作为各种装置或器件(包括天线、电路板、发光器件、显 示器件等)基板、覆盖膜或保护膜、触摸屏面板、屏下摄像头用透明基板等。
本申请还提供一种用于制备本申请实施例第四方面、第五方面或第六方面所述的聚合物薄膜的装置。
附图说明
图1为本申请实施例提供的电子器件100的结构示意图；
图2为本申请实施例提供的柔性OLED发光器件100a的结构示意图；
图3为本申请实施例提供的设备200的结构示意图；
图4为实施例1和实施例2的聚酰亚胺薄膜的动态热机械分析(DMA)曲线图；
图5为实施例1和实施例2的聚酰亚胺薄膜的热重分析(TGA)曲线图；
图6为实施例1和实施例2的聚酰亚胺薄膜的紫外可见吸收曲线。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例进行说明。
随着目前以手机为代表的消费电子对透明显示的需求不断增长，越来越高的屏占比趋势推动手机前置摄像头已经经历了刘海屏、水滴屏、挖孔屏、摄像头升降屏、滑盖屏等多重演进方案。但受限于尚无量产可用的满足高温制程的耐高温透明聚酰亚胺材料，真正意义上的屏下摄像头方案的全面屏一直无法制造。具体地，在柔性有机发光二极管(OLED)器件的制备流程中，如制作薄膜晶体管(TFT层)等，通常会经历接近500℃高温的处理过程，作为基底材料的聚酰亚胺薄膜如果与其他材料的热膨胀程度不匹配，将会造成剥离、开裂、翘曲等问题。当前手机用柔性显示屏一般使用顶发光工艺的柔性OLED器件(AMOLED)，光线从阴极发出，LTPS(低温多晶硅)TFT背板不需要光线穿过，所以使用黄色聚酰亚胺浆料涂布膜作为基板即可。而对于屏下摄像头(即摄像头放置在显示屏下方)来说，在使用摄像头的时候，需要外界光线穿过LTPS(低温多晶硅)TFT背板膜，这样摄像头才能够捕捉到光线，因此必须使用高透光率的柔性聚酰亚胺来实现。
为实现真正意义上屏下摄像头方案的全面屏，本申请实施例提供一种采用特定单体聚合而成的聚酰胺酸，该聚酰胺酸作为制备聚酰亚胺的前驱体通过结合特定工艺制备成聚酰亚胺薄膜，可以兼具良好热力学性能和良好光学性能，具体地，该聚酰亚胺薄膜具有优异耐热性(Tg≥400℃)、超低热膨胀系数CTE(≤10ppm/K)、优异机械性能及良好的透光率和低黄度(YI)值，从而可以满足显示屏中柔性电子元器件的应用需求，有望在电子装置如装置基板、覆盖膜、触摸屏面板、屏下摄像头用透明基板等场景中得到应用。
具体地，本申请实施例提供一种聚酰胺酸，该聚酰胺酸包括衍生自芳香族二酐和芳香族二胺的重复单元，芳香族二酐和/或芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。其中，芳香族二酐和/或芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子是指，构成上述芳香环的至少一个碳原子上直接连接有氟原子，氟原子与构成芳香环的碳原子形成C-F单键，例如芳香环为苯环，苯环上至少一个碳原子上直接连接有氟原子，即该碳位上的取代基为氟原子。
本申请实施例提供的聚酰胺酸为制备聚酰亚胺的前驱体材料，聚酰胺酸包括衍生自芳香族二酐和芳香族二胺的重复单元，即聚酰胺酸采用具有芳香结构的芳香族二酐和芳香族二胺进行共聚，采用芳香结构的单体有利于聚酰亚胺薄膜获得良好热力学性能，且芳香结构的单体有利于抑制分子链的堆积，赋予聚酰亚胺良好的透明性及热性能；另外，芳香族二酐和/或 芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，这样可降低电荷转移络合物(CTC)的形成，而且可以通过特定的薄膜成型工艺使得聚酰亚胺分子链通过C-F单键发生部分交联，从而进一步提升聚酰亚胺的热力学性能(包括耐热性和尺寸稳定性等)，同时兼具良好的光学性能(包括高透光率、低黄度指数等)。
本申请实施方式中，芳香族二酐和/或芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，即C-F单键可以是通过芳香族二酐单体引入，也可以是通过芳香族二胺单体引入，还可以是由芳香族二酐单体和芳香族二胺单体引入。其中，芳香族二酐和/或芳香族二胺可以通过芳香环上的一个碳原子引入一个C-F单键，也可以是通过芳香环上的多个碳原子引入多个C-F单键。
本申请一些实施方式中，芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，芳香族二胺的结构可以是如通式(1)所示：
H2N-R-NH2通式(1)，
其中，通式(1)中的R表示具有1-10个苯环的芳香基团，且R中部分或全部苯环上的至少一个碳原子通过C-F单键连接有氟原子，苯环上未连接有氟原子的碳位上连接氢原子、烷基、氟代烷基或苯基。具有通式(1)结构的含氟芳香族二胺单体作为聚酰亚胺前驱体的制备原料，可以有效降低电荷转移络合物(CTC)的形成，且经由特定工艺处理后聚酰亚胺可以通过C-F单键发生分子链部分交联，从而有效改善聚酰亚胺薄膜的透明性，同时赋予聚酰亚胺薄膜高玻璃化转变温度、高热失重温度、低热膨胀系数等优异热力学性能。
其中，R具体可以是具有1个苯环的取代苯环、也可以是具有2个或2个以上苯环的取代联苯结构等，取代联苯结构具体可以是取代的二联苯结构、取代的三联苯结构、取代的四联苯结构等。
一些实施例中，R为取代苯环，此时，芳香族二胺的结构通式(1)可以表示为(1-A1)或(1-A2)，
式(1-A1)和式(1-A2)中，a为1至4的整数，a具体可以是1、2、3、4，即苯环上可以通过C-F单键连接有1、2、3或4个氟原子；b＝4-a，b为0至3的整数，具体为0、1、2、或3；R1是苯环上未连接有氟原子的碳位上连接的基团，R1可以是氢原子、烷基、氟代烷基或苯基。
一些实施例中，R为取代的二联苯结构，此时，芳香族二胺的结构通式(1)可以表示为(1-B)，
式(1-B)中，两个苯环上的c分别独立地为1至4的整数，c具体可以是1、2、3、4，即每个苯环上可以通过C-F单键连接有1、2、3或4个氟原子；两个苯环上连接的氟原子的个数可以是相同，也可以是不同；d＝4-c，d为0至3的整数，具体为0、1、2、或3；R2是苯环上未连接有氟原子的碳位上连接的基团，两个苯环上的R2可以是分别独立地为氢原子、烷基、氟代烷 基或苯基；两个苯环上连接的R2的个数可以是相同，也可以是不同；两个苯环上的R2可以是相同基团，也可以是不同基团。
一些实施例中，R为取代的三联苯结构，此时，芳香族二胺的结构通式(1)可以表示为(1-C)，
式(1-C)中，三个苯环上的e分别独立地为1至4的整数，e具体可以是1、2、3、4，即每个苯环上可以通过C-F单键连接有1、2、3或4个氟原子；三个苯环上连接的氟原子的个数可以是相同，也可以是不同；f＝4-e，f为0至3的整数，具体为0、1、2、或3；R3是苯环上未连接有氟原子的碳位上连接的基团，三个苯环上的R3可以是分别独立地为氢原子、烷基、氟代烷基或苯基；三个苯环上连接的R3的个数可以是相同，也可以是不同；三个苯环上的R3可以是相同基团，也可以是不同基团。
一些实施例中，R为取代的四联苯结构，此时，芳香族二胺的结构通式(1)可以表示为(1-D)，
式(1-D)中，四个苯环上的e分别独立地为1至4的整数，e具体可以是1、2、3、4，即每个苯环上可以通过C-F单键连接有1、2、3或4个氟原子；四个苯环上连接的氟原子的个数可以是相同，也可以是不同；f＝4-e，f为0至3的整数，具体为0、1、2、或3；R4是苯环上未连接有氟原子的碳位上连接的基团，四个苯环上的R4可以是分别独立地为氢原子、烷基、氟代烷基或苯基；四个苯环上连接的R4的个数可以是相同，也可以是不同；四个苯环上的R4可以是相同基团，也可以是不同基团。
本申请实施方式中，上述芳香族二胺的分子结构中，烷基可以是碳原子数为1-10的非取代烷基，具体例如可以是甲基、乙基、正丙基、异丙基、正丁基、异丁基、叔丁基、戊基等。氟代烷基可以是碳原子数为1-10的氟取代烷基，氟代烷基可以是部分氟取代或全氟取代烷基，具体例如可以是氟代甲基(如三氟甲基)、氟代乙基、氟代正丙基、氟代异丙基、氟代正丁基、氟代异丁基、氟代叔丁基、氟代戊基等。
本申请一些具体实施例中，芳香族二胺可以是选自式(1-1)至(1-12)中的任意一种或多种：

本申请实施方式中，芳香族二胺单体可以是包括一种或多种，具体可以是包括(1-1)至(1-12)中的任意一种或多种。本申请实施例上述芳香族二胺单体易得，且具有较好刚性，有利于赋予聚酰亚胺良好的透明性及热性能。
本申请实施方式中，当芳香族二胺中的芳香环上的碳原子通过C-F单键引入有氟原子时，芳香族二酐可以是选自式(2-1)至(2-17)中的任意一种或多种：

本申请实施例芳香族二酐的刚性非平面结构可以有效抑制聚合物分子链的堆积，赋予聚酰亚胺良好的透明性及热性能。本申请实施方式中，芳香族二酐单体可以是包括一种或多种，具体可以是包括(2-1)至(2-17)中的任意一种或多种。
本申请实施方式中，以衍生自二酐的全部结构单元为100mol％计，衍生自芳香族二酐的结构单元的摩尔占比为50％至100％。即聚酰胺酸分子结构中，衍生自二酐的结构单元可以是全部源自上述芳香族二酐，此时，衍生自芳香族二酐的结构单元的摩尔占比为100％；也可以是一部分源自上述芳香族二酐，此时，衍生自芳香族二酐的结构单元的摩尔占比为大于或等于50％且小于100％，具体地，衍生自芳香族二酐的结构单元的摩尔占比可以是50％、60％、70％、80％、90％、95％等。衍生自芳香族二酐的结构单元的摩尔占比控制在较高占比有利于提升聚酰亚胺薄膜的热力学性能。
本申请一些实施方式中，为了使聚酰亚胺薄膜获得更好的光学性能，可以是在聚酰胺酸的制备过程中引入适量刚性脂环结构的二酐单体，即同时采用芳香族二酐和刚性脂环结构的二酐两类单体与芳香族二胺进行共聚。该实施方式中，聚酰胺酸还包括衍生自刚性脂环结构的二酐和上述芳香族二胺的重复单元。通过向聚酰亚胺结构中引入非芳香的脂环结构，可以破坏原芳香族聚酰亚胺链段上的共轭结构，减弱分子链间的相互作用，减弱甚至消除电荷转移络合物(CTC)效应从而改善聚酰亚胺薄膜的透光率，同时增大分子链间的距离，有助于改善聚酰亚胺的溶解性。但由于脂环结构的二酐的反应活性普遍比芳香族二酐低，且脂环结构的耐热性与芳香结构相比差距明显，因此，脂环结构的二酐会不利于聚酰亚胺获得高玻璃化转变温度、高热失重温度、低热膨胀系数等优异热力学性能，因此，需要将脂环结构的二酐的引入量控制在适合范围。
本申请实施方式中，以衍生自二酐的全部结构单元为100mol％计，衍生自刚性脂环结构的二酐的结构单元的摩尔占比为5％至50％。具体地，衍生自芳香族二酐的结构单元的摩尔占比可以是5％、8％、10％、15％、20％、30％、40％、50％等。一些实施方式中，以衍生自二酐的全部结构单元为100mol％计，衍生自刚性脂环结构的二酐的结构单元的摩尔占比为5％至15％。将刚性脂环结构的二酐单体的量控制在较小量，有利于在改善聚酰亚胺薄膜光学性能的情况下，获得更优异的热力学性能。
本申请实施方式中，刚性脂环结构的二酐包括式(3-1)至(3-4)中的任意一种或多种：
本申请一些实施方式中，聚酰胺酸由一种或多种芳香族二酐单体与一种或多种芳香族二胺单体聚合而成，单体为全芳香结构，此时聚酰胺酸仅包括衍生自芳香族二酐和芳香族二胺的重复单元。本申请一些实施方式中，聚酰胺酸由一种或多种芳香族二酐单体、一种或多种刚性脂环结构的二酐与一种或多种芳香族二胺单体聚合而成，此时聚酰胺酸包括衍生自芳香 族二酐和芳香族二胺的重复单元，还包括衍生自刚性脂环结构的二酐和芳香族二胺的重复单元。
下面以式(2-3)所示的芳香族二酐与式(1-8)所示的芳香族二胺为单体共聚形成聚酰胺酸为例，说明聚酰胺酸的具体分子结构，该实施方式中，聚酰胺酸的结构式如式(Ia)所示：
式(Ia)中，聚酰胺酸包括衍生自式(2-3)所示的芳香族二酐与式(1-8)所示的芳香族二胺的重复单元，式(1-8)所示的芳香族二胺中的芳香环上的四个碳原子通过C-F单键连接有四个氟原子；1表示重复单元的重复次数，即聚合度，为使聚合物具有较好的成膜性和力学性能，1可以是大于或等于10的整数，具体例如可以是10-100、15-100的整数。
以式(2-3)所示的芳香族二酐、式(3-2)所示的刚性脂环结构的二酐、与式(1-8)所示的芳香族二胺为单体共聚形成聚酰胺酸为例，说明聚酰胺酸的具体分子结构，该实施方式中，聚酰胺酸的结构式如式(Ib)所示：
式(Ib)中，聚酰胺酸包括衍生自式(2-3)所示的芳香族二酐与式(1-8)所示的芳香族二胺的第一重复单元，以及衍生自式(3-1)所示的刚性脂环结构的二酐与式(1-8)所示的芳香族二胺的第二重复单元；x、y表示重复单元的摩尔占比，x+y＝1，x为0.5至0.95，y为0.05至0.5。
本申请实施例相应提供一种聚酰胺酸溶液，该聚酰胺酸溶液包括本申请实施例上述的聚酰胺酸和有机溶剂。
本申请实施方式中，聚酰胺酸溶液的固含量可以是5％-50％。即聚酰胺酸溶液中，聚酰胺酸的质量含量可以是5％-50％；一些实施例中，聚酰胺酸的质量含量可以是10％-35％；一些实施例中，聚酰胺酸的质量含量可以是15％-25％。聚酰胺酸具有适合的固含量，有利于通过成膜工艺获得具有适合厚度和良好综合性能的聚酰亚胺薄膜。本申请一些实施方式中，聚酰胺酸溶液中还可以根据实际应用需要加入其他组分，例如填料等。填料具体可以是无机填料。
本申请实施方式中，有机溶剂可以是包括N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)、γ-丁内酯(GBL)、N-甲基吡咯烷酮(NMP)、间甲酚(m-Cresol)中的一种或多种。
本申请实施例还提供一种聚酰亚胺薄膜，由上述聚酰胺酸溶液制备得到。具体地，聚酰亚胺薄膜可以是通过将聚酰胺酸溶液涂覆成膜后，再经酰亚胺化得到。
具体地，本申请实施例提供一种聚酰亚胺薄膜的制备方法，包括：
将本申请实施例提供的聚酰胺酸溶液涂覆至基板上，经过除溶剂后，置于真空或保护气 氛中进行热处理完成酰亚胺化，得到聚酰亚胺薄膜；其中，热处理包括由室温经梯度升温程序或连续升温程序升至355℃-450℃，在355℃-450℃保温0.05h-2h。
本申请一些实施方式中，热处理过程中的梯度升温程序包括：由室温升至60℃-100℃保持0.5h-2h,再升温至130℃-180℃保持0.5h-2h,再升温至230℃-300℃/0.5h-2h,再升温至355℃-450℃。通过多梯度升温保温控制，有利于酰亚胺化的完成，形成性能更均匀稳定的聚酰亚胺薄膜。
本申请一些实施方式中，热处理过程中的连续升温程序包括：由室温以1-10℃/m11的升温速率连续升温至355℃-450℃。一些实施方式中，升温速率可以是1℃/m11、2℃/m11、3℃/m11、4℃/m11、5℃/m11、6℃/m11、7℃/m11、8℃/m11、9℃/m11、10℃/m11。适合的升温速率控制，有利于酰亚胺化的完成，形成性能更均匀稳定的聚酰亚胺薄膜。
上述制备方法中，基板可以是玻璃基板。除溶剂操作可以是在氩气、氮气或空气气氛下进行，具体可以是在上述气氛中于30-120℃范围内保持0.1h至8h。上述热处理可以是在真空或保护气氛下的烘箱中进行，其中保护气氛可以是氢气和氩气混合气氛、氢气和氮气混合气氛、氩气气氛或氮气气氛。本申请的特殊热处理工艺，可以在实现聚酰胺酸酰亚胺化的同时，实现聚酰亚胺分子链的部分交联，从而使聚酰亚胺获得良好光学性能的同时获得更好的热力学性能。
本申请实施方式中，在355℃-450℃保温0.05h-2h具体可以是在355℃、360℃、370℃、380℃、400℃、410℃、420℃、430℃、450℃等温度下保温0.05h、0.1h、0.2h、0.3h、0.4h、0.5h、0.6h、0.8h、1h、1.5h或2h等。
本申请实施方式中，完成热处理后，可以是在自然降温至室温后，将覆盖聚酰亚胺薄膜的基板浸泡于去离子水中，加热使聚酰亚胺薄膜从基板上剥离下来，得到聚酰亚胺薄膜。
本申请实施方式中，聚酰亚胺薄膜包括聚酰亚胺，聚酰亚胺包括衍生自芳香族二酐和芳香族二胺的重复单元，芳香族二酐和/或芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子；聚酰亚胺薄膜中，部分聚酰亚胺通过C-F单键发生交联。
以上述式(2-3)所示的芳香族二酐与式(1-8)所示的芳香族二胺为单体共聚形成聚酰胺酸为例，该实施方式中，聚酰亚胺的结构式如式(Ⅱa)所示：
式(Ⅱa)中，聚酰胺酸包括衍生自式(2-3)所示的芳香族二酐与式(1-8)所示的芳香族二胺的重复单元，式(1-8)所示的芳香族二胺中的芳香环上的四个碳原子通过C-F单键连接有四个氟原子；m表示重复单元的重复次数，即聚合度，为使聚合物具有较好的成膜性和力学性能，m可以是大于或等于10的整数，具体例如可以是10-100、15-100的整数。聚酰亚胺薄膜中，部分聚酰亚胺通过C-F单键发生交联，即聚酰亚胺薄膜中，部分聚酰亚胺可能以如下式(Ⅱb)所示的交联方式存在。
式(Ⅱb)中，m1、m2表示重复单元的重复次数。
本申请实施方式中，聚酰亚胺薄膜的厚度可以是2μm4100μm；一些实施例中，聚酰亚胺薄膜的厚度为5μm450μm；一些实施例中，聚酰亚胺薄膜的厚度为20μm450μm；本申请实施方式中，聚酰亚胺薄膜的厚度具体例如可以是2μm、5μm、8μm、10μm、15μm、20μm、25μm、30μm、35μm、40μm、50μm、60μm、70μm、80μm、90μm、100μm。
本申请实施例的聚酰亚胺薄膜具有良好的光学性能和良好的热力学性能，具体地，聚酰亚胺薄膜在4001m-7801m范围内(可见光区)的平均透光率≥75％；一些实施例中，聚酰亚胺薄膜在4001m-7801m范围内的平均透光率≥78％；一些实施例中，聚酰亚胺薄膜在4001m-7801m范围内的平均透光率≥80％。聚酰亚胺薄膜基于ASTM E313标准的黄度值(YI)＜15。黄色指数(YI)用来表征无色透明、半透明或近白色的高分子材料发黄(黄变)的程度。YI值越大，样品颜色越黄，反之颜色越蓝。一些实施例中，聚酰亚胺薄膜基于ASTM E313标准的黄度值(YI)＜10。本申请实施例的聚酰亚胺薄膜在D65光源下的b值小于10，浊度小于1％。本申请实施例的聚酰亚胺薄膜的玻璃转化温度(Tg)≥400℃；一些实施例中，聚酰亚胺薄膜的玻璃转化温度(Tg)≥420℃。本申请实施例的聚酰亚胺薄膜在40℃4400℃范围的热膨胀系数(CTE)≤10ppm/K；一些实施例中，聚酰亚胺薄膜在40℃4400℃范围的热膨胀系数(CTE)在-10ppm/K至10ppm/K。本申请实施例的聚酰亚胺薄膜在氮气下的1％热重损失温度(Td1％)＞500℃；一些实施例中，聚酰亚胺薄膜在氮气下的1％热重损失温度(Td1％)≥520℃；一些实施例中，聚酰亚胺薄膜在氮气下的1％热重损失温度(Td1％)≥550℃；一些实施例中，聚酰亚胺薄膜在氮气下的1％热重损失温度(Td1％)≥580℃。本申请实施例的聚酰亚胺薄膜还具有优异的机械性能，本申请实施例的聚酰亚胺薄膜的拉伸强度大于120MPa，弹性模量大于或等于5GPa，断裂伸长率大于或等于5％。本申请实施例的聚酰亚胺薄膜可以满足显示屏中柔性电子元器件的应用需求，可在电子设备中的装置基板、覆盖膜或保护膜、触摸屏面板、屏下摄像头用透明基板等场景中得到应用，具体可以是用于柔性显示器用基板或保护膜等。
本申请实施例还提供上述聚酰亚胺薄膜在制备柔性基板、通讯设备绝缘材料、电子设备绝缘材料、电机绝缘材料、电器绝缘材料中的应用。
参见图1，本申请实施例还提供一种电子器件100，电子器件100具体可以是柔性器件，电子器件100包括基板10和设置在基板10上的功能层20，其中，基板10包括本申请实施例上述的聚酰亚胺薄膜。
本申请实施方式中，电子器件100可以是各种需要使用聚酰亚胺薄膜作为衬底或盖板的 器件，例如可以是包括透明天线、柔性电路板、发光器件、显示器件、照明器件、太阳能电池等。针对不同电子器件可以是在基板10上设置不同的功能层20。例如，透明天线的功能层20可以是包括导电层等；柔性电路板的功能层20可以是包括导电层等；发光器件的功能层20可以是包括发光层等；太阳能电池的功能层20可以是包括吸光层等。
参见图2，以柔性OLED发光器件100a为例，柔性OLED发光器件100a的功能层可以是包括依次形成在聚酰亚胺薄膜10上的薄膜晶体管层(TFT层)201、发光层202、触控层203、偏光片层204、光学胶层205、盖板206(可以是聚酰亚胺或UTG玻璃等)。其制备过程可以是包括，将本申请实施例提供的聚酰胺酸溶液涂覆在玻璃基板上，经热处理形成聚酰亚胺薄膜后，在聚酰亚胺薄膜上制备上述OLED发光器件功能层，再剥离玻璃基板，得到柔性OLED发光器件。其中盖板206也可以采用本申请实施例的聚酰亚胺薄膜。
参见图3，本申请实施例还提供一种设备200，设备200可以是电子设备或通讯设备，设备200包括本申请实施例上述的聚酰亚胺薄膜。设备200可以是手机、平板电脑、笔记本电脑、便携机、可穿戴设备、电视机、录像机、摄录机、收音机、收录机等。具体地，聚酰亚胺薄膜在设备200中可以是作为透明天线、柔性电路板、发光器件、显示器件等的基板。如图3所示，设备200为手机，手机包括显示屏201，显示屏201包括柔性OLED发光器件100a，柔性OLED发光器件100a采用聚酰亚胺薄膜作为基板。
本申请实施例还提供一种用于制备本申请实施例上述聚酰亚胺薄膜的装置。该装置可以实现本申请实施例上述聚酰亚胺薄膜的制备，该装置可以是包括涂布组件、热处理组件等。
应理解，本文中涉及的第一、第二以及各种数字编号仅为描述方便进行的区分，并不用来限制本申请的范围。本申请中，“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A,B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。本申请中，“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，“a,b,或c中的至少一项(个)”，或，“a,b,和c中的至少一项(个)”，均可以表示：a,b,c,a-b(即a和b),a-c,b-c,或a-b-c，其中a,b,c分别可以是单个，也可以是多个。
下面分多个实施例对本申请实施例进行进一步的说明。
实施例1
(1)将1,4-二羧基四氟苯与四丁基溴化铵Bu4NBr反应，得到1,4-二溴四氟苯；将1,4-二溴四氟苯加入三口瓶中，加入对氨基苯硼酸和催化剂四(三苯基磷)钯，再加入THF和2M碳酸钾水溶液后抽真空通氮气，升温到80℃开始反应，反应18h，硅胶柱提纯，得到上文式(1-8)所示的芳香族二胺单体TP4F。步骤(1)的反应过程如下：
(2)在氮气保护下，在反应瓶中加入芳香族二胺单体(1-8)后加入N,N-二甲基乙酰胺DMAc，室温下搅拌至溶解，缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA，室温搅拌24h得无色透明的粘稠状聚酰胺酸溶液，加入N,N-二甲基乙酰胺DMAc将聚酰胺酸溶液稀释至固含量为10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至120℃预烘60m11得预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中进行热处理，热处理操作具体为以3℃/m11升温速率从室温升至400℃-410℃，维持10-20m11，热处理后冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的高性能聚酰亚胺薄膜。步骤(2)的反应过程如下：
本申请实施例的聚酰亚胺薄膜中可能部分聚酰亚胺分子发生交联。表1为实施例1热处理前后的聚合物薄膜的元素分析结果。热处理前为聚酰胺酸膜，热处理后为聚酰亚胺薄膜。
表1
表1的元素分析结果显示，经热处理后的聚酰亚胺薄膜的F含量相对热处理前的聚酰胺酸膜明显降低，结合热处理前后膜的性能变化，表明发生了一定程度的脱F现象形成交联结构。
通过热机械分析(TMA)测试获得聚酰亚胺薄膜的热膨胀系数CTE；通过动态热机械分析(DMA)测试获得薄膜的玻璃化转变温度Tg；通过热重分析仪(TGA)测试获得聚酰亚胺薄膜的1％热失重温度Td1％；以及通过紫外可见吸收光谱仪对聚酰亚胺薄膜在400-7801m范围内的平均透光率进行测试，基于ASTM E313标准对其黄度指数YI值进行测试，通过拉伸试验对聚酰亚胺薄膜的拉伸模量、拉伸强度、断裂伸长率进行测试。其中，拉伸模量是指材料在拉伸时的弹性，其值为将材料沿中心轴方向拉伸单位长度所需的力与其横截面积的比。 拉伸强度是指材料产生最大均匀塑性变形的应力，在拉伸试验中，试样直至断裂为止所受的最大拉伸应力即为拉伸强度。断裂伸长率是试样在拉断时的位移值与原长的比值。
经测试可知，本申请实施例1得到的聚酰亚胺薄膜在404400℃范围热膨胀系数CTE约为-8ppm/K，Tg>430℃，Td1％>550℃，拉伸模量>8GPa，拉伸强度>280MPa，且可见光区平均透光率>78％，基于ASTM E313标准的黄度指数YI值小于10。本申请实施例1的聚酰亚胺薄膜的综合性能非常突出，兼具优异的光学性能、热力学性能和机械力学性能，特别是具有高Tg、Td1％和超低CTE，从而不仅可以满足透明需求，还可以满足高耐热、高尺寸稳定性、高强度、高柔韧性等性能需求。本申请实施例1的聚酰亚胺膜具有上述优异性能，主要是由于全芳香刚直链结构使聚酰亚胺自身的耐热性能及力学性能优异，二胺单体中C-F键的引入减弱了二胺单体的给电子能力，使得(电荷转移络合物)CTC效应减弱，光学性能改善；而且在特定热处理工艺作用下，薄膜成型过程中聚酰亚胺发生部分交联，使得聚酰亚胺薄膜的热膨胀系数CTE进一步降低，从而最终获得兼具有优异热力学性能、光学性能和机械力学性能的柔性聚酰亚胺薄膜。
实施例2
在氮气保护下，将实施例1制备的芳香族二胺单体(1-8)和N,N-二甲基乙酰胺DMAc加入至反应瓶中，室温下搅拌至溶解，然后缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA和9,9-双(3,4-二羧基苯基)芴二酸酐，室温搅拌24h得到无色透明的粘稠状聚酰胺酸溶液，加入DMAc将聚酰胺酸溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至120℃预烘60m11得到预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中进行热处理，热处理操作具体为以3℃/m11升温速率从室温升至400℃-410℃，维持10-20m11，热处理后冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的无色透明聚酰亚胺薄膜。上述反应过程如下：
上述结构式中，x为0.7，y为0.3。
经测试可知，本申请实施例2得到的聚酰亚胺薄膜在404400℃范围热膨胀系数CTE约为6.2ppm/K，Tg>430℃，Td1％>500℃，拉伸模量>5GPa，拉伸强度>150MPa，且可见光区平均透光率>80％，基于ASTM E313标准的黄度指数YI值小于10。本申请实施例2的聚酰亚胺薄膜的综合性能非常突出，兼具优异的光学性能、热力学性能和机械力学性能，特别是具有高Tg、Td1％和超低CTE，从而不仅可以满足透明需求，还可以满足高耐热、高尺寸稳定性、高强度、高柔韧性等性能需求。本申请实施例2的聚酰亚胺膜具有上述优异性能，主要是由于全芳香刚直链结构使聚酰亚胺自身的耐热性能及力学性能优异，二胺单体中C-F键的引入 减弱了二胺单体的给电子能力，使得(电荷转移络合物)CTC效应减弱，光学性能改善；本申请实施例2还引入了大体积扭曲结构的共聚单体9,9-双(3,4-二羧基苯基)芴二酸酐，破坏了分子链的有序堆砌，减弱了分子链间相互作用，进一步改善了光学性能；而且在特定热处理工艺作用下，薄膜成型过程中聚酰亚胺发生部分交联，使得聚酰亚胺薄膜的热膨胀系数CTE进一步降低，从而最终获得兼具有优异热力学性能、光学性能和机械力学性能的柔性聚酰亚胺薄膜。
图4为本申请实施例1和实施例2的聚酰亚胺薄膜的动态热机械分析(DMA)曲线图；由图4可以获知聚酰亚胺薄膜的玻璃化转变温度Tg，实施例1的聚酰亚胺薄膜的玻璃化转变温度Tg为437℃；实施例2的聚酰亚胺薄膜的玻璃化转变温度Tg为427℃。图5为本申请实施例1和实施例2的聚酰亚胺薄膜的热重分析(TGA)曲线图；由图5可知聚酰亚胺薄膜的1％热失重温度Td1％，实施例1的聚酰亚胺薄膜的1％热失重温度Td1％为560℃；实施例2的聚酰亚胺薄膜的1％热失重温度Td1％为520℃。图6为本申请实施例1和实施例2的聚酰亚胺薄膜的紫外可见吸收曲线；由图6可知聚酰亚胺薄膜在可见光区的透光率，实施例1的聚酰亚胺薄膜在可见光区的平均透光率为79％；实施例2的聚酰亚胺薄膜在可见光区的平均透光率为82.5％。
实施例3
(1)取间氟硝基苯加入三口烧瓶，再加入乙醇和饱和NaOH水溶液，搅拌过程中加入锌粉，加热回流12h后趁热过滤，用少量乙醇洗涤，旋蒸除去乙醇后用氯仿萃取，乙醇重结晶，得到橙红色固体偶氮化合物；将偶氮化合物溶于丙酮中，加入锌粉再加入饱和氯化铵水溶液快速搅拌，直至溶液橙红色消失，倒入10％的氨水后过滤，滤液用氯仿萃取，得到白色固体；取白色固体溶于50mL乙醇中，加入30mL浓盐酸后室温搅拌6h，再加入饱和NaOH溶液至混合溶液成碱性，氯仿萃取后硅胶柱提纯(PE：DCM＝1:2)，得到白色固体，即上文式(1-5)所示的芳香族二胺单体TP2F。上述反应过程如下：
(2)在氮气保护下，在反应瓶中加入芳香族二胺单体TP2F后加入N,N-二甲基乙酰胺DMAc，室温下搅拌至溶解，缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA，室温搅拌24h得到无色透明的粘稠状聚酰胺酸溶液，再加入DMAc将聚酰胺酸溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至120℃预烘60m11得到预烘干的聚酰胺酸膜；随后将玻璃板转移至还原炉(内置气氛为氢氮混合气)中进行热处理，热处理操作具体为以3℃/m11升温速率从室温升至400℃-410℃，维持10-20m11，热处理后冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的高性能聚酰亚胺薄膜。上述反应过程如下：
经测试可知，本申请实施例3得到的聚酰亚胺薄膜在404400℃范围热膨胀系数CTE约为-8ppm/K，Tg>430℃，Td1％>550℃，且可见光区平均透光率>75％，基于ASTM E313标准的黄度指数YI值小于15。本申请实施例3的聚酰亚胺薄膜的综合性能突出，兼具优异的光学性能和热力学性能，特别是具有高Tg、Td1％和超低CTE，从而不仅可以满足透明需求，还可以满足高耐热、高尺寸稳定性、高强度、高柔韧性等性能需求。本申请实施例3的聚酰亚胺膜具有上述优异性能，主要是由于全芳香刚直链结构使聚酰亚胺自身的耐热性能及力学性能优异，二胺单体中C-F键的引入减弱了二胺单体的给电子能力，使得(电荷转移络合物)CTC效应减弱，光学性能改善；而且在特定热处理工艺作用下，薄膜成型过程中聚酰亚胺发生部分交联，使得聚酰亚胺薄膜的热膨胀系数CTE进一步降低，从而最终获得兼具有优异热力学性能和光学性能的柔性聚酰亚胺薄膜。
实施例4
在氮气保护下，将实施例1制备的芳香族二胺单体(1-8)和N,N-二甲基乙酰胺DMAc加入至反应瓶中，室温下搅拌至溶解，然后缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA和式(3-1)所示的刚性脂环结构二酐，室温搅拌24h得到无色透明的粘稠状聚酰胺酸溶液，加入DMAc将聚酰胺酸溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至120℃预烘60m11得到预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中进行热处理，热处理操作具体为以3℃/m11升温速率从室温升至400℃-410℃，维持10-20m11，热处理后冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的无色透明聚酰亚胺薄膜。上述反应过程如下：

上述结构式中，x为0.9，y为0.1。
经测试可知，本申请实施例4得到的聚酰亚胺薄膜在404400℃范围热膨胀系数CTE约为10ppm/K，Tg≥430℃，Td1％>500℃，拉伸模量≥5GPa，拉伸强度≥150MPa，且可见光区平均透光率>80％，基于ASTM E313标准的黄度指数YI值小于10。本申请实施例4的聚酰亚胺薄膜的综合性能突出，兼具优异的光学性能和热力学性能，特别是具有高Tg、Td1％和超低CTE，从而不仅可以满足透明需求，还可以满足高耐热、高尺寸稳定性、高强度、高柔韧性等性能需求。本申请实施例4的聚酰亚胺膜具有上述优异性能，主要是由于芳香刚直链结构和刚性脂环结构单体使聚酰亚胺自身的耐热性能及力学性能优异，二胺单体中C-F键的引入减弱了二胺单体的给电子能力，使得(电荷转移络合物)CTC效应减弱，光学性能改善；而且在特定热处理工艺作用下，薄膜成型过程中聚酰亚胺发生部分交联，使得聚酰亚胺薄膜的热膨胀系数CTE进一步降低，从而最终获得兼具有优异热力学性能和光学性能的柔性聚酰亚胺薄膜。
对比例1
在氮气保护下，在反应瓶中加入二胺单体TFMB后加入N,N-二甲基乙酰胺DMAc室温下搅拌至溶解，缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA，室温搅拌24h得无色透明的粘稠状聚酰胺酸溶液，加入DMAc将聚酰胺酸溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至80℃预烘120m11得预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中以一定程序升温(80℃保温1h→150℃保温1h→250℃保温2h→390℃保温0.5h)，冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的聚酰亚胺薄膜。二胺单体TFMB的结构式如下：
对比例2
在氮气保护下，在反应瓶中加入实施例制备的芳香族二胺单体TP4F后，再加入N,N-二甲基乙酰胺DMAc室温下搅拌至溶解，缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA，室温搅拌24h得无色透明的粘稠状聚酰胺酸溶液，加入DMAc将聚酰胺酸溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至120℃预烘60m11得预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中以一定程序升温(由室温以升温速率3℃/m11升温至350℃，并在350℃维持30m11)，冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的聚酰亚胺薄膜。
对比例3
在氮气保护下，在反应瓶中加入TFMB后加入N,N-二甲基乙酰胺DMAc(26.8mL)室温下搅拌至溶解，缓慢加入3,3’,4,4’-联苯四羧酸二酐BPDA与1,2,4,5-环己烷四甲酸二酐(式(3-1)所示))，室温搅拌24h得无色透明的粘稠状聚酰胺酸溶液，加入DMAc将聚酰胺酸 溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至80℃预烘120m11得预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中以一定程序升温(80℃保温1h→150℃保温1h→250℃保温2h→350℃保温0.5h)，冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的聚酰亚胺薄膜。
对比例4
在氮气保护下，在反应瓶中加入TFMB后加入N,N-二甲基乙酰胺DMAc室温下搅拌至溶解，缓慢加入六氟异丙基邻苯二甲酸酐(式(2-7)所示))，室温搅拌24h得到无色透明的粘稠状聚酰胺酸溶液，加入DMAc将聚酰胺酸溶液稀释至固含量10％，过滤除去不溶杂质，抽真空除气泡后刮涂于玻璃板上，置于水平加热台上，升温至80℃预烘120m11得到预烘干的聚酰胺酸膜，将玻璃板转移至还原炉(内置气氛为氢氮混合气)中以一定程序升温(80℃保温1h→150℃保温1h→250℃保温2h→350℃保温0.5h)，冷却至室温后浸泡于热水中脱膜，得到膜厚为10±1μm的聚酰亚胺薄膜。
将实施例1至实施例3，对比例1至对比例4制得的聚酰亚胺薄膜的性能参数汇总于表2。
表2
由表2的性能参数结果可以获知，本申请实施例1至实施例4制备的聚酰亚胺薄膜具有比对比例1-4的聚酰亚胺薄膜更好的综合性能，特别是本申请实施例的聚酰亚胺薄膜在具有较高的可见光区透光率的同时，具有高玻璃化转变温度Tg、高热失重温度Td1％和低热膨胀系数CTE，即兼具高耐热、高尺寸稳定性和良好光学性能，能够更好地满足电子设备中高透明高耐热高尺寸稳定性透明基板的应用需求。这主要是由于本申请实施例1-4的聚酰亚胺采用具有芳香结构的芳香族二酐和芳香族二胺(全芳香结构单体)进行共聚，或者采用芳香结构的芳香族二酐、刚性脂环结构的二酐与芳香族二胺(芳香和脂环结构单体)进行共聚获得，且芳香族二胺的芳环碳位上通过C-F单键连接有氟原子，其中，采用芳香和脂环结构的单体 有利于聚酰亚胺薄膜获得良好热力学性能和机械力学性能，且芳香结构和脂环结构的单体有利于抑制分子链的堆积，赋予聚酰亚胺良好的透明性及热性能；且芳香族二胺中的芳香环上的碳原子通过C-F单键连接有氟原子，这样可降低电荷转移络合物(CTC)的形成，而且可以通过特定的热处理成膜工艺使得聚酰亚胺分子链通过C-F单键发生部分交联，从而进一步提升聚酰亚胺的热力学性能，同时兼具良好的光学性能。
其中，对比实施例1和对比例2可以获知，虽然对比例2采用与实施例1相同的单体进行聚酰亚胺薄膜的制备，但对比例2的聚酰亚胺薄膜的玻璃化转变温度Tg和高热失重温度Td1％均低于实施例1，对比例2的聚酰亚胺薄膜的热膨胀系数CTE远高于实施例1，这是由于对比例2的热处理工艺与实施例1不同，实施例1通过采用特定的热处理工艺使得聚酰亚胺分子发生了部分交联，从而进一步提高了聚酰亚胺薄膜的热力学性能，以及进一步降低了聚酰亚胺薄膜的热膨胀系数CTE。

Claims (25)

  1. 一种聚合物前驱体，其特征在于，所述聚合物前驱体为聚酰胺酸，所述聚合物前驱体包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。
  2. 如权利要求1所述的聚合物前驱体，其特征在于，所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子，所述芳香族二胺的结构如通式(1)所示：
    H2N-R-NH2通式(1)，
    其中，R表示具有1-10个苯环的芳香基团，且R中部分或全部所述苯环上的至少一个碳原子通过C-F单键连接有氟原子，所述苯环上未连接有氟原子的碳位上连接氢原子、烷基、氟代烷基或苯基。
  3. 如权利要求2所述的聚合物前驱体，其特征在于，所述芳香族二胺选自式(1-1)至(1-12)中的任意一种或多种：
  4. 如权利要求1-3任一项所述的聚合物前驱体，其特征在于，所述芳香族二酐选自式(2-1)至(2-17)中的任意一种或多种：

  5. 如权利要求1-4任一项所述的聚合物前驱体，其特征在于，以衍生自二酐的全部结构单元为100mol％计，衍生自所述芳香族二酐的结构单元的摩尔占比为50％至100％。
  6. 如权利要求1所述的聚合物前驱体，其特征在于，所述聚合物前驱体还包括衍生自刚性脂环结构的二酐和所述芳香族二胺的重复单元。
  7. 如权利要求6所述的聚合物前驱体，其特征在于，以衍生自二酐的全部结构单元为100mol％计，衍生自所述刚性脂环结构的二酐的结构单元的摩尔占比为5％至50％。
  8. 如权利要求6或7所述的聚合物前驱体，其特征在于，所述刚性脂环结构的二酐包括式(3-1)至(3-4)中的任意一种或多种：
  9. 一种前驱体溶液，其特征在于，所述前驱体溶液包括权利要求1-8任一项所述的聚合物前驱体和有机溶剂。
  10. 如权利要求9所述的前驱体溶液，其特征在于，所述前驱体溶液的固含量为5％-50％。
  11. 如权利要求9或10所述的前驱体溶液，其特征在于，所述有机溶剂包括N,N-二甲基乙酰胺、N,N-二甲基甲酰胺、γ-丁内酯、N-甲基吡咯烷酮、间甲酚中的一种或多种。
  12. 一种聚合物薄膜的制备方法，其特征在于，包括：
    将权利要求9-11任一项所述的前驱体溶液涂覆至基板上，经过除溶剂后，置于真空或保护气氛中进行热处理完成酰亚胺化，得到聚合物薄膜；
    所述热处理包括由室温经梯度升温程序或连续升温程序升至355℃-450℃，在355℃-450℃保温0.05h-2h。
  13. 如权利要求12所述的制备方法，其特征在于，所述梯度升温程序包括：由室温升至60℃-100℃保持0.5h-2h,再升温至130℃-180℃保持0.5h-2h,再升温至230℃-300℃/0.5h-2h, 再升温至355℃-450℃。
  14. 如权利要求12所述的制备方法，其特征在于，所述连续升温程序包括：由室温以1-10℃/m11的升温速率连续升温至355℃-450℃。
  15. 一种聚合物薄膜，其特征在于，所述聚合物薄膜采用权利要求9-11任一项所述的前驱体溶液制备得到，或采用权利要求12-14任一项所述的制备方法制备得到。
  16. 一种聚合物薄膜，其特征在于，所述聚合物薄膜包括聚合物，所述聚合物包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。
  17. 如权利要求16所述的聚合物薄膜，其特征在于，所述聚合物薄膜中，部分所述聚合物通过所述C-F单键发生交联。
  18. 一种聚合物薄膜，其特征在于，所述聚合物薄膜在4001m-7801m范围内的平均透光率≥75％；基于ASTM E313标准的黄度值YI＜15；玻璃转化温度Tg≥400℃；40℃4400℃范围的热膨胀系数CTE≤10ppm/K；氮气下1％热重损失温度＞500℃。
  19. 如权利要求18所述的聚合物薄膜，其特征在于，所述聚合物薄膜包括聚合物，所述聚合物包括衍生自芳香族二酐和芳香族二胺的重复单元，所述芳香族二酐和/或所述芳香族二胺中的芳香环上的至少一个碳原子通过C-F单键连接有氟原子。
  20. 如权利要求18或19所述的聚合物薄膜，其特征在于，所述聚合物薄膜的厚度为2μm4100μm。
  21. 如权利要求15-20任一项所述的聚合物薄膜在制备柔性基板、通讯设备绝缘材料、电子设备绝缘材料、电机绝缘材料、电器绝缘材料中的应用。
  22. 一种电子器件，其特征在于，所述电子器件包括权利要求15-20任一项所述的聚合物薄膜。
  23. 如权利要求22所述的电子器件，其特征在于，所述电子器件包括透明天线、柔性电路板、发光器件、显示器件、照明器件或太阳能电池。
  24. 一种设备，所述设备为电子设备或通讯设备，其特征在于，所述设备包括权利要求15-20任一项所述的聚合物薄膜，或者包括权利要求22或23所述的电子器件。
  25. 一种用于制备权利要求15-20任一项所述的聚合物薄膜的装置。
PCT/CN2023/095283 2022-05-31 2023-05-19 聚合物前驱体、聚合物薄膜及其制备方法 WO2023231807A1 (zh)

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