A high-transmittance polyimide film substrate, film coating, composite film material, and their preparation and application.

Abstract

This invention, entitled "A High-Transmittance Polyimide Film Main Material, Film Coating, Composite Film Material, and Their Preparation and Application," belongs to the field of materials technology. Addressing the problems of easy surface cracking and significant degradation of optical performance after radiation in existing transparent anti-ionic oxygen polyimide films, this invention provides a polyimide film with high optical transparency and strong anti-ionic oxygen erosion resistance. The key technical point is a high-transmittance polyimide film main material, comprising an aromatic phosphorus-containing diamine, an alicyclic dianhydride monomer, and an organic solvent; the aromatic phosphorus-containing diamine is 2,5-bis[(4-aminophenoxy)phenyl]diphenyloxyphosphine; the alicyclic dianhydride monomer is selected from at least one of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, and 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a high-transmittance polyimide film substrate, film coating, composite film material, and their preparation and application. Background Technology

[0002] Polyimide is one of the best heat-resistant engineering plastics currently in industrial production due to its excellent heat resistance, thermal stability, mechanical strength, dielectric properties, chemical resistance, and radiation resistance, as well as its outstanding toughness and flexibility. Polyimide is generally prepared by first forming a polyamic acid precursor from equimolar amounts of diamine and dianhydride in a polar protic solvent, and then through either a thermal imide method or a chemical imide method.

[0003] In recent years, with the continuous advancement of human exploration technology, the low-Earth orbit economy, with low-Earth orbit satellites at its core, has enormous development potential and a broad market prospect. This has also placed higher performance requirements on high-performance polyimide films used in low-Earth orbit space exploration. For example, in aerospace optoelectronic devices, the films are required to have not only excellent resistance to atomic oxygen erosion, but also excellent optical transparency to meet the comprehensive requirements of materials in space exploration applications.

[0004] Traditional polyimide films are difficult to process due to their typical structural characteristics, and their color tends to be dark, usually brown or yellow, which is not conducive to their promotion and application in the optical field. At the same time, most existing electronic-grade commercial transparent polyimide films have poor resistance to atomic oxygen erosion and cannot meet the environmental tolerance requirements of low-altitude exploration missions.

[0005] Therefore, the development of transparent anti-proton oxygen polyimide materials has received widespread attention from the scientific and industrial communities in recent years. To improve the anti-proton oxygen properties of transparent polyimides, numerous researchers have employed methods such as surface evaporation, sputtering, and matrix doping. However, these methods generally have an adverse effect on the optical transparency of the thin film. While evaporation and sputtering can effectively improve the anti-proton oxygen erosion performance of the thin film, the film surface is prone to cracking, resulting in a "drilling" phenomenon. Inorganic doping modification introduces dispersion problems, and the optical properties of the thin film significantly decrease after AO radiation.

[0006] This document, published in China (CN114717751A) on June 20, 2023, discloses an atomic oxygen-resistant polyimide nanofiber membrane, its preparation method, and its applications. The document introduces cage-like polysilsesquioxane (POSS) and diphenylphosphine (PPO) structures into the polyimide structure, generating a silica passivation layer and a phosphate protective layer upon atomic oxygen erosion, thereby giving the polyimide nanofiber membrane excellent long-term resistance to atomic oxygen erosion.

[0007] This document, published in China (CN118255989A) on June 28, 2024, discloses a polyimide precursor solution and a polyimide film. The polyimide film is prepared from the polyimide precursor solution, which is prepared through a specific polymerization reaction of dianhydride and diamine. The dianhydride includes at least one of a primary dianhydride and a secondary dianhydride, and the diamine includes at least one of a primary diamine and a secondary diamine. The precursor solution is then dried to obtain a pre-coated film; the pre-coated film is then imidized at high temperature to obtain the polyimide film. The polyimide film prepared in this document exhibits good transparency, resistance to atomic oxygen radiation, and excellent overall heat resistance. It is easy to process and suitable for use in aerospace, flexible optoelectronics, and other fields, particularly as structural components or protective materials for equipment in space exploration.

[0008] The prior art represented by the aforementioned documents has at least the following unresolved technical problems or defects: (1) The conflict between optical transparency and antigen oxygen performance cannot be satisfied. The relevant evidence is: Publication No. CN114717751A, which discloses that antigen oxygen performance is achieved by introducing aromatic dianhydride and POSS structure into the polyimide main chain. However, the aromatic structure has a conjugated system, which leads to the film color being yellowish and the light transmittance being insufficient.

[0009] (2) The long-term effectiveness and stability of the atomic oxygen protective layer are insufficient. The relevant evidence is: Publication No. CN114717751A. This literature only constructs a protective layer using a single element (silicon) of POSS, lacking the synergistic protection of phosphorus element, and the atomic oxygen erosion rate is too high. This literature uses electrospinning to prepare nanofiber membranes. The gaps between fibers are large, and AO can easily penetrate and erode the substrate through the gaps. After long-term exposure, there is a risk of "drilling" corrosion. Summary of the Invention

[0010] The purpose of this invention is to provide: A high-transmittance polyimide film substrate material, film coating, composite film material, and related technologies, to solve technical problems such as improving the transmittance of polyimide films after atomic oxygen radiation, or combinations thereof.

[0011] Terminology Explanation: Unless otherwise defined, all technical terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this subject matter pertains. Unless otherwise stated, all patents, patent inventions, and disclosures cited throughout this document are incorporated herein by reference in their entirety. Where multiple definitions exist for terms herein, the definitions provided in this chapter shall prevail.

[0012] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0013] Definitions of standard chemical terms can be found in the references "Polyimide - Relationship between Chemistry, Structure and Properties and Materials (2nd Edition)", "Polyimide / Monomer Synthesis and Polymerization Methods and Materials Preparation", and "GB / T 13542.6-2006" (Films for Electrical Insulation - Part 6: Polyimide Films).

[0014] Unless otherwise stated, conventional methods within the scope of the art, such as spectrophotometer testing, cross-cut test, etc., shall be used.

[0015] Unless specifically defined herein, the use of all commercially available products herein employs standard techniques. For example, it may be carried out using the manufacturer's instructions for use with the kit, or in accordance with methods known in the art or the description of this invention. The techniques and methods described herein can generally be implemented according to conventional methods well known in the art, based on the descriptions in the various summary and more specific documents cited and discussed in this specification.

[0016] The term "polyimide" as used in this article refers to a high molecular weight polymer containing repeating imide ring units, formed by the polymerization reaction of diamine monomers and dianhydride monomers to form a polyamic acid precursor, followed by an imidization reaction to close the ring. It has excellent heat resistance, mechanical properties and environmental stability.

[0017] The term "aromatic phosphorus-containing diamine" as used in this article refers to diamine compounds that simultaneously contain an aromatic ring, a phosphorus element, and two amino groups (-NH2) in their molecular structure. These compounds can be used as comonomers in the synthesis of polyimides to impart specific functions to the polymer (such as resistance to atomic oxygen and flame retardancy).

[0018] The term "alicyclic dianhydride monomer" as used in this article refers to monomeric compounds whose molecular structure contains an alicyclic (non-aromatic) skeleton and two anhydride functional groups (-CO-O-CO-), which can be copolymerized with diamines to prepare transparent polyimide materials, avoiding yellowing caused by aromatic ring conjugation.

[0019] The terms "2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine" and "BADPO" used in this article refer to: [BADPO] with the molecular formula C 36 H 28 N2O3P can be introduced into the polyimide structure to form a phosphate protective layer, thereby improving its resistance to atomic oxygen.

[0020] The terms “1,2,3,4-cyclobutanetetracarboxylic acid dianhydride” and “CBDA” used in this article refer to: CAS No. 2420-87-3, molecular formula C8H4O6, which is the core monomer for the preparation of transparent polyimide.

[0021] The terms "1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride" and "DM-CBDA" used in this article refer to: [chemical formula: C...] 10 H8O6 contains two methyl substituents in its molecular structure. The molecular core is a cyclobutane alicyclic skeleton. Two methyl groups are substituted at positions 1 and 3, and a carboxyl anhydride group (-CO-O-CO-) is attached at positions 1, 2, 3, and 4. It can improve the solubility and processability of polyimide.

[0022] The terms "1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride" and "TM-CBDA" used in this article refer to: CAS number 64198-16-9, molecular formula C 12 H 12 O6, with a molecular weight of 252.22, has a cyclobutane alicyclic skeleton at its core, with one methyl group and one carboxyl anhydride group substituted at positions 1, 2, 3, and 4. The methyl substitution can significantly improve the transparency and processing stability of polyimide.

[0023] The term "polyimide film coating" used in this article refers to a coating applied to the surface of a polyimide-based film after the copolymerization of diamine and dianhydride to form polyamic acid, with the addition of additives and fillers. Its main function is to improve the resistance to atomic oxygen.

[0024] The term "filler" as used in this article refers to reinforcing materials added to optimize the performance of polyimide composite films, including glass fiber, nano-zirconia, nano-silica, nano-mica sheets, nano-talc, etc.

[0025] The term "polyimide-based film" as used in this article refers to a polyimide film (referred to as the base film) that possesses basic mechanical, optical, or insulating properties and serves as the core substrate of a composite film. It is typically a homogeneous PI film prepared commercially or through standard processes, and can be further functionally modified (e.g., antigenic oxygen, high thermal conductivity) through coating, lamination, etc. Its thickness, light transmittance, mechanical strength, and other properties must meet the requirements of subsequent processing and applications.

[0026] The term "polymerization reaction" as used in this article refers to the process in which diamine monomers and dianhydride monomers undergo a condensation reaction in an aprotic, strongly polar solvent under inert atmosphere and specific temperature conditions to form a polyamic acid mixture.

[0027] The term "mixing" as used in this article refers to the process of uniformly integrating components such as diamine / dianhydride monomers, solvents, additives, and fillers to form a homogeneous or stable dispersion system through methods such as mechanical stirring, ultrasonic dispersion, and planetary mixing. The core objective is to ensure that the reaction proceeds fully and that the filler does not agglomerate, laying the foundation for subsequent film formation and uniform performance. Key parameters such as stirring rate, temperature, and time need to be controlled.

[0028] The term "precursor liquid" as used in this article refers to the core intermediate material before film formation, typically a polyamic acid (PAA) solution (generated by polymerization of diamine and dianhydride in a highly polar solvent). Additives, inorganic fillers, or other modifying components may be added according to functional requirements. The precursor liquid must possess specific viscosity and stability to meet the requirements of film formation processes such as coating and casting.

[0029] The term "coating" as used in this article refers to the process of uniformly applying a precursor solution to the surface of a substrate (such as glass, PET release film, or polyimide-based film) using a specific process to form a continuous and uniform wet film. Common coating methods in film preparation include cast coating, doctor blade coating, roll coating, and spray coating. Precise control of coating thickness, speed, and ambient humidity is required to ensure that the wet film is free of defects such as pinholes, bubbles, and uneven thickness.

[0030] The term "drying" as used in this article refers to the process of removing solvents and trace amounts of moisture from the system by placing the coated wet film in a specific temperature environment and using methods such as hot air convection, vacuum heating, and infrared radiation. The core purpose is to avoid blistering, cracking, or uneven shrinkage of the film due to rapid solvent evaporation during the subsequent curing stage, and to form a stable pre-coated film after drying.

[0031] The term "curing" as used in this article refers to the process of causing a closed-loop reaction of the polyamic acid molecular chain in the dried pre-coated film through thermal imidization, chemical imidization, or a combination of thermochemical imidization, to form a stable polyimide film containing repeating imide ring units.

[0032] In a first aspect, the present invention provides: a high-transmittance polyimide film substrate material, comprising an aromatic phosphorus-containing diamine, an alicyclic dianhydride monomer, and an organic solvent; wherein the aromatic phosphorus-containing diamine is 2,5-bis[(4-aminophenoxy)phenyl]diphenyloxyphosphine; and the alicyclic dianhydride monomer is selected from at least one of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, and 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride.

[0033] The technical features include: 2,5-bis[(4-aminophenoxy)phenyl]diphenyloxyphosphine, alicyclic dianhydride monomer, and organic solvent.

[0034] The organic solvent is selected from at least one of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, γ-butyrolactone, dimethyl sulfoxide, dimethylformamide, m-cresol, ethyl acetate, and acetone. The type of organic solvent is preferably at least one of N-methyl-2-pyrrolidone, N,N-dimethylacetamide and γ-butyrolactone; The type of organic solvent is further preferably N,N-dimethylacetamide; Preferably, the alicyclic dianhydride monomer is 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride; Preferably, in the polyimide film host material, the molar mass ratio of the aromatic phosphorus-containing diamine to the alicyclic dianhydride monomer is 0.95-1:1-1.1; For example, the molar ratio of the aromatic phosphorus-containing diamine to the alicyclic dianhydride monomer can be: 0.96-1:1-1.05, 0.97-0.99:1-1.05, 0.98-1:1-1.07, 0.99-1:1-1.09, 0.97-0.98:1-1.01 or 0.95-0.99:1-1.03; For example, the molar ratio of the aromatic phosphorus-containing diamine to the alicyclic dianhydride monomer can be: 0.95:1, 0.95:1.1, 1:1, 1:1.1, 0.96:1, 0.97:1, 0.98:1, 0.99:1, 0.99:1.01, 0.99:1.05, 0.99:1.1 or 0.98:1.1; More preferably, in the polyimide film host material, the molar mass ratio of the aromatic phosphorus-containing diamine to the alicyclic dianhydride monomer is 1:1; Preferably, the solid content of the polyimide film substrate is 12wt%-25wt%.

[0035] Based on further solutions to the technical problems of the present invention, or simultaneous solutions to multiple technical problems, the preferred solution in the technical solution provided in the first aspect of the present invention includes: The first preferred embodiment: the organic solvent is selected from at least one of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, γ-butyrolactone, dimethyl sulfoxide, dimethylformamide, m-cresol, ethyl acetate, and acetone; preferably at least one of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and γ-butyrolactone; more preferably N,N-dimethylacetamide. This technical solution, based on solving the technical problem of "improving transmittance, interfacial adhesion, and resistance to atomic oxygen erosion," further solves the technical problem of "further improving transmittance, interfacial adhesion, and resistance to atomic oxygen erosion."

[0036] The second preferred embodiment: the alicyclic dianhydride monomer is selected from at least one of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, and 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride; preferably 1,2,3,4-cyclobutanetetracarboxylic dianhydride. This technical solution, based on solving the technical problem of "improving transmittance, interfacial adhesion performance, and resistance to atomic oxygen erosion," further solves the technical problem of "further improving transmittance, interfacial adhesion performance, and resistance to atomic oxygen erosion."

[0037] The third preferred embodiment is that the molar mass ratio of the aromatic phosphorus-containing diamine to the alicyclic dianhydride monomer is 0.95-1:1-1.1; preferably 1:1. This technical solution, based on solving the technical problem of "improving transmittance, interfacial adhesion performance and resistance to atomic oxygen erosion", further solves the technical problem of "further improving transmittance, interfacial adhesion performance and resistance to atomic oxygen erosion".

[0038] In a second aspect, the present invention provides a polyimide film coating comprising a polyimide film substrate and fillers.

[0039] It includes the following technical features: polyimide film as the main material and filler.

[0040] Preferably, the packing material is an inorganic packing material; More preferably, the filler is selected from at least one of glass fiber, nano-zirconium dioxide, nano-silica, nano-mica flakes, nano-talc, graphene, carbon fiber and ceramic fiber; More preferably, the filler is nano-silica; The mass ratio of the polyimide film substrate to the filler is 1:0.5-1.25. The preferred mass ratio of the polyimide film substrate material to the filler is 1:0.5-1; The mass ratio of the polyimide film substrate material to the filler is further preferably 1:1; Preferably, the polyimide film coating further comprises other auxiliary materials; More preferably, the other auxiliary materials are at least one of catalyst, dehydrating agent, antioxidant, heat stabilizer, color modifier, antistatic agent and tear-resistant agent; More preferably, the catalyst includes, but is not limited to, at least one of pyridine, 4-dimethylaminopyridine (DMAP), triethylamine, and 2,4,6-trimethylpyridine; Most preferably, the catalyst is pyridine; More preferably, the dehydrating agent includes, but is not limited to, at least one of acetic anhydride, propionic anhydride, trifluoroacetic anhydride, and phthalic anhydride; Most preferably, the dehydrating agent is acetic anhydride; More preferably, the antioxidant includes, but is not limited to, at least one of hindered phenols (1010, 1098), phosphites (168), and thioethers (DLTPs); More preferably, the heat stabilizer includes, but is not limited to, at least one of lanthanum oxide, cerium oxide, benzophenone derivatives, and organotin compounds; More preferably, the color modifier includes, but is not limited to, at least one of carbon black, titanium dioxide, iron oxide, phthalocyanine blue, and nano zinc oxide; More preferably, the antistatic agent includes, but is not limited to, at least one of conductive carbon black, carbon nanotubes, graphene, nano-tin dioxide, and quaternary ammonium salt modified montmorillonite; More preferably, the tear-resistant agent includes, but is not limited to, at least one of glass fiber, carbon fiber, silicon carbide whiskers, nano-silica, and organically modified montmorillonite.

[0041] Based on further solutions to the technical problems of the present invention, or simultaneous solutions to multiple technical problems, the preferred solution in the technical solution provided in the second aspect of the present invention includes: The first preferred embodiment is that the mass ratio of the polyimide film substrate material to the filler is 1:0.5-1.25; preferably 1:0.5-1; and more preferably 1:1. This technical solution, based on solving the technical problem of "improving transmittance, interfacial adhesion performance and resistance to atomic oxygen erosion", further solves the technical problem of "further improving transmittance, interfacial adhesion performance and resistance to atomic oxygen erosion".

[0042] Thirdly, the present invention provides: a polyimide composite film material, the composition of which includes: the polyimide film coating and the polyimide base film.

[0043] Among them are the technical features: polyimide film coating and polyimide-based film.

[0044] The polyimide composite film material has a two-layer structure of "polyimide film coating - polyimide base film" or a three-layer structure of "polyimide film coating - polyimide base film - polyimide film coating"; The polyimide-based film is a commercially available transparent polyimide film or one prepared by conventional methods in the art; The thickness of the polyimide-based film is 12.5-125 μm; The thickness of the polyimide-based film is preferably 12.5-25 μm; The thickness of the polyimide-based film is further preferably 25 μm; For example, the polyimide-based film can be a commercially available HC-25 type transparent polyimide film or a CVW-25 type transparent polyimide film; Preferably, the thickness of the polyimide film coating is less than or equal to 1 / 2 of the thickness of the polyimide base film.

[0045] Preferably, the transmittance of the polyimide composite film material at 550 nm is equal to or greater than that of the polyimide base film, and the haze is equal to or less than 1.0%. Preferably, the atomic oxygen erosion resistance rate of the polyimide composite film material is less than or equal to 0.5 × 10⁻⁶. - 24 atom / cm 3 ; Preferably, the polyimide composite film material can still achieve a light transmittance of over 80% after atomic oxygen radiation.

[0046] Fourthly, the present invention provides a method for preparing the polyimide composite film material, comprising the steps of: S1. Mix aromatic phosphorus-containing diamine and alicyclic dianhydride monomer in an organic solvent and carry out a polymerization reaction to obtain the polyimide film substrate material; S2. The polyimide film substrate material obtained in S1 is mixed with filler and auxiliary materials to obtain the precursor liquid of the polyimide film coating; S3. The precursor liquid obtained in S2 is coated onto the polyimide-based film, and after drying and curing, the polyimide composite film material is obtained.

[0047] The technical features include: polymerization reaction, mixing, precursor liquid, coating, drying, and curing.

[0048] Wherein, the mixing method described in S1 is selected from at least one of mechanical stirring, oscillating mixing, and ultrasonic mixing; The preferred mixing method described in S1 is mechanical stirring; Preferably, the mixing order in S1 is as follows: first, the aromatic phosphorus-containing diamine is mixed with an organic solvent, and then it is mixed with an alicyclic dianhydride monomer; The polymerization reaction in S1 takes 24-48 hours. The polymerization reaction described in S1 is carried out under an inert atmosphere.

[0049] The mixing method described in S2 includes, but is not limited to, at least one of mechanical stirring, oscillating mixing, and ultrasonic mixing; The preferred mixing method described in S2 is mechanical stirring; Preferably, the mixing sequence in S2 is as follows: the polyimide film substrate material is first mixed with the auxiliary material, and then mixed with the filler.

[0050] The coating method described in S3 includes, but is not limited to, at least one of blade coating, cast coating, roller coating, slot coating, two-roller coating, and spin coating. The preferred coating method described in S3 is scraper coating; The drying method described in S3 includes, but is not limited to, at least one of oven drying, vacuum drying, vacuum freeze drying, dryer drying, distillation drying, and infrared drying. The preferred drying method described in S3 is oven drying; The drying method described in S3 is further preferably drying in a blower oven; The drying temperature described in S3 is 50-180℃; The drying temperature described in S3 is preferably 100°C; The drying time described in S3 is 5-60 minutes; The drying time described in S3 is preferably 10 minutes; Wherein, the curing method described in S3 is at least one of thermal curing, chemical curing, and thermochemical curing; The curing method described in S3 is preferably thermal curing; The curing method described in S3 is further preferably nitrogen oven heat curing; The curing method described in S3 is further preferably heat curing in a nitrogen oven with an oxygen concentration of <100ppm; Preferably, the thermosetting temperature is 250-350℃; More preferably, the thermosetting temperature is 300°C; Preferably, the thermosetting time is 5-60 minutes; More preferably, the thermosetting time is 10 minutes.

[0051] Based on further solutions to the technical problems of the present invention, or simultaneous solutions to multiple technical problems, the preferred solution in the technical solution provided in the fourth aspect of the present invention includes: The first preferred embodiment: the mixing method is selected from at least one of mechanical stirring, oscillating mixing, and ultrasonic mixing; preferably, mechanical stirring; preferably, the mixing sequence is to first mix the aromatic phosphorus-containing diamine with the organic solvent, and then mix it with the alicyclic dianhydride monomer. This technical solution, while solving the technical problem of "improving interfacial adhesion performance," further solves the technical problem of "further improving interfacial adhesion performance."

[0052] The second preferred embodiment: the drying temperature in S3 is 50-180℃; preferably 100℃; the drying time in S3 is 5-60min; preferably 10min. This technical solution, based on solving the technical problem of "improving interfacial adhesion performance", further solves the technical problem of "further improving interfacial adhesion performance".

[0053] The third preferred embodiment: the curing method described in S3 is preferably thermal curing; more preferably, it is thermal curing in a nitrogen oven; even more preferably, it is thermal curing in a nitrogen oven with an oxygen concentration of <100ppm; preferably, the thermal curing temperature is 250-350℃; more preferably, the thermal curing temperature is 300℃; preferably, the thermal curing time is 5-60min; even more preferably, the thermal curing time is 10min. This technical solution, while solving the technical problem of "improving interfacial adhesion performance," further solves the technical problem of "further improving interfacial adhesion performance."

[0054] Fifthly, the present invention provides the application of the polyimide composite film material in the fields of flexible optoelectronics and aerospace.

[0055] This includes technical features such as flexible optoelectronics and applications in the aerospace field.

[0056] Preferably, the application is as follows: the polyimide composite film material can be used as a substrate or protective material for related equipment or devices in the optoelectronic field of space exploration technology.

[0057] Examples 1-9 of this invention at least support the protection scope of "alicyclic dianhydride monomer", "aromatic phosphorus-containing diamine", "filler" and "polyimide-based film".

[0058] The term "alicyclic dianhydride monomer" is derived from the aforementioned explanation and / or the corresponding technical feature in Examples 1-9, which states that "the alicyclic dianhydride monomer is selected from at least one of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, and 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride," and is summarized by the common feature "a monomeric compound whose molecular structure contains an alicyclic (non-aromatic) skeleton and has two anhydride functional groups (-CO-O-CO-). Therefore, those skilled in the art can reasonably presume that "alicyclic dianhydride monomer," its subordinate concepts, its substantially equivalent technical means, and technical means that can replace "alicyclic dianhydride monomer" within the scope of conventional technical means and common knowledge based on the existing level of technology should all fall within the protection scope of "alicyclic dianhydride monomer."

[0059] The term "aromatic phosphorus-containing diamine" is derived from the aforementioned explanation and / or the corresponding technical feature in Examples 1-9, "the aromatic phosphorus-containing diamine is 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine," and is summarized by the common feature "a diamine compound whose molecular structure simultaneously contains an aromatic ring, a phosphorus element, and two amino groups (-NH2)." Therefore, those skilled in the art can reasonably presume that "aromatic phosphorus-containing diamine," its subordinate concepts, its substantially equivalent technical means, and technical means that can replace "aromatic phosphorus-containing diamine" based on existing technology and conventional technical means and common knowledge should all fall within the protection scope of "aromatic phosphorus-containing diamine."

[0060] The term "filler" is derived from the foregoing explanation and / or the corresponding technical features in Examples 1-9, such as "the type of filler is nano-silica" and "the mass ratio of the polyimide film main material to the filler is 1:0.5-1.25," and is summarized by the common feature "reinforcing material added to optimize the performance of the polyimide composite film." Therefore, those skilled in the art can reasonably presume that "filler," its subordinate concepts, its essentially equivalent technical means, and technical means that can replace "filler" based on existing technology and conventional technical means and common knowledge should all fall within the protection scope of "filler."

[0061] The term "polyimide-based film" is derived from the foregoing explanation and / or the corresponding technical features in Examples 1-9, such as "the polyimide-based film is a commercially available or conventionally prepared transparent polyimide film" and "the thickness of the polyimide-based film is 12.5-125 μm," and is summarized by the common feature "possessing basic mechanical, optical, or insulating properties, serving as a core substrate of a composite film." Therefore, those skilled in the art can reasonably presume that "polyimide-based film," its subordinate concepts, its substantially equivalent technical means, and technical means that can replace "polyimide-based film" within the scope of conventional technical means and common knowledge based on the existing level of technology should all fall within the protection scope of "polyimide-based film."

[0062] Examples 1-9 of this invention at least support the protection scope of "polymerization reaction", "curing", "precursor liquid" and "coating".

[0063] The term "polymerization reaction" is derived from the aforementioned explanation and / or the corresponding technical features in Examples 1-9, such as "the polymerization reaction time in S1 is 24-48 hours" and "the polymerization reaction is carried out under an inert atmosphere," through the common feature "the process in which diamine monomers and dianhydride monomers undergo a condensation reaction in an aprotic strongly polar solvent under inert atmosphere and specific temperature conditions to form a polyamic acid mixture." Therefore, those skilled in the art can reasonably presume that "polymerization reaction," its subordinate concepts, its essentially equivalent technical means, and technical means that can replace it within the scope of conventional technical means and common knowledge based on the existing level of technology should all fall within the protection scope of "polymerization reaction."

[0064] "Cure" is defined by the foregoing explanation and / or the corresponding technical features in Examples 1-9, such as "the curing method is at least one of thermal curing, chemical curing, and combined thermochemical curing," and is summarized by the common feature "the process of forming a stable polyimide film containing repeating imide ring units by thermal imidization, chemical imidization, or combined thermochemical imidization of the dried pre-coated film." Therefore, those skilled in the art can reasonably presume that "curing," its subordinate concepts, its essentially equivalent technical means, and technical means that can replace A within the scope of conventional technical means and common knowledge based on the existing technical level should all fall within the protection scope of "curing."

[0065] The term "precursor liquid" is derived from the foregoing explanation and / or the corresponding technical features in Examples 1-9, such as "the precursor liquid for the polyimide film coating is obtained by mixing the polyimide film substrate material obtained in S1 with fillers and additives," and is further summarized by the common feature "the core intermediate material before film formation, usually a polyamic acid (PAA) solution (generated by polymerization of diamine and dianhydride in a strongly polar solvent), which can be supplemented with additives, inorganic fillers, or other modified components according to functional requirements." Therefore, those skilled in the art can reasonably presume that "precursor liquid," its subordinate concepts, its essentially equivalent technical means, and technical means that can replace "precursor liquid" within the scope of conventional technical means and common knowledge based on the existing technical level should all fall within the protection scope of "precursor liquid."

[0066] The term "coating" is derived from the foregoing explanation and / or the corresponding technical feature in Examples 1-9, which states that "the coating method includes, but is not limited to, at least one of blade coating, cast coating, roller coating, slot coating, two-roller coating, and spin coating," and is summarized by the common feature "the operation of uniformly applying a precursor liquid to the surface of a substrate (such as glass, PET release film, or polyimide-based film) through a specific process to form a continuous and uniform wet film." Therefore, those skilled in the art can reasonably presume that the technical feature "coating," its subordinate concepts, its substantially equivalent technical means, and technical means that can replace "coating" based on existing technology and conventional technical means and common knowledge should all fall within the protection scope of "coating."

[0067] In this invention, embodiments 1-9 at least support the protection scope of "applications in the fields of flexible optoelectronics and aerospace".

[0068] The term "applications in flexible optoelectronics and aerospace" is summarized from the foregoing explanation and / or the corresponding technical feature in Examples 1-9, such as "the polyimide composite film material can be used as a substrate or protective material for related equipment or devices in the optoelectronic field of space exploration technology." Therefore, those skilled in the art can reasonably infer that "applications in flexible optoelectronics and aerospace," its subordinate concepts, its essentially equivalent technical means, and technical means that can replace it within the scope of conventional and common knowledge based on the existing level of technology should all fall within the protection scope of this invention.

[0069] The beneficial effects of this invention are as follows: The present invention has at least the following beneficial effects: (1) The transparent atomic oxygen polyimide resin and composite film preparation method disclosed in this invention are simple. At the same time, the composite film has excellent resistance to atomic oxygen erosion and good optical transmittance. The adhesion between the base film and the coating is excellent. It also maintains the basic physical properties of the transparent polyimide film base film, such as flexibility and heat resistance. Therefore, the prepared composite polyimide film has excellent comprehensive performance, convenient process, and is conducive to processing and molding.

[0070] (2) The present invention prepares a transparent polyimide composite resin by mixing a specific diamine with a specific dianhydride and adding additives and fillers. The resin is then coated onto a transparent polyimide base film prepared by conventional commercial use or conventional methods in the art. The optical properties and atomic oxygen resistance of the polyimide composite film are controlled. It is found that the polyimide composite film prepared by coating with this mixture has better resistance to atomic oxygen erosion while maintaining excellent optical properties. At the same time, the optical transparency of the composite film can still be maintained at a high rate after AO erosion, which significantly improves the application effect of transparent atomic films in the field of space exploration.

[0071] (3) Compared with the prior art, the present invention has better technical effects in terms of light transmittance after atomic oxygen radiation and resistance to atomic oxygen erosion rate.

[0072] According to experimental tests, the present invention increases the light transmittance of the thin film to over 80% after atomic oxygen radiation.

[0073] According to experimental tests, this invention reduces the atomic oxygen erosion resistance rate from 0.071 × 10⁻⁶ in the prior art. -24 atom / cm 3 Reduced to 0.031×10 -24 atom / cm 3 the following.

[0074] Furthermore, based on the present invention: 1. Based on the comparison of Example 2 and Comparative Examples 1-2, the present invention employs a specific technical means to combine the diamine "2,5-bis[(4-aminophenoxy)phenyl]diphenyloxyphosphine" with dianhydride, achieving better technical effects: "higher light transmittance and lower yellow index". The combined technical effect is superior to the sum of the effects of each individual technical means.

[0075] 2. Based on the comparison of Example 2 and Comparative Examples 3-4, the present invention purposefully selects from the broad scope disclosed in the prior art a narrower scope not mentioned in the prior art, namely, "the alicyclic dianhydride monomer is selected from at least one of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, and 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride", and achieves unexpected technical effects such as "higher light transmittance and lower yellow index".

[0076] 3. Based on the comparison of Examples 1-3 and Comparative Examples 5-6, the present invention, without disclosing specific combination formulas in the prior art, purposefully selects a narrow range not mentioned in the prior art, namely "the mass ratio of the polyimide film main material to the filler is 1:0.5-1.25", and achieves unexpected technical effects such as "higher light transmittance and lower yellow index". Attached Figure Description

[0077] Figure 1 The above is the 1H NMR spectrum of BADPO prepared in the basic embodiment. Detailed Implementation

[0078] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0079] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all instruments, devices, equipment, reagents, products, etc., used in the embodiments of the present invention are obtained through conventional commercial means.

[0080] Specific raw material information is shown in Table 1: Table 1. Raw Material Information

[0081] Basic Implementation The 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO) used in the subsequent specific embodiments was prepared in the laboratory, and the specific preparation method is as follows: (1) Synthesis of intermediate dinitro compound (BNDPO) 2,5-Dihydroxyphenyl(diphenyl)phosphine oxide (DHDPO), 1-fluoro-4-nitrobenzene, anhydrous CsF, and distilled DMAc were added to a three-necked flask. The mixture was stirred at room temperature for 30 minutes and then refluxed under a nitrogen atmosphere for 24 hours. The reaction solution was filtered while hot, and the filtrate was poured into excess water. The precipitate was collected by filtration, washed with water, and dried under vacuum at 60°C for 24 hours to obtain BNDPO.

[0082] (2) Catalytic reduction synthesis of BADPO Add the BNDPO obtained in step (1), anhydrous ethanol, and 5% Pd / C catalyst to a three-necked flask and heat to reflux. Add hydrazine hydrate dropwise over 1.5 hours and continue reflux for 24 hours. Filter while hot to remove the catalyst. Add distilled water to the filtrate until a white precipitate forms. Filter and collect the precipitate, then wash with cold ethanol. Dry under vacuum at 80°C overnight to obtain BADPO.

[0083] The hydrogen NMR spectrum of the obtained BADPO is shown in the figure. Figure 1 .

[0084] Example 1 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1020 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then add the nano-silica dispersion to the mixture at a solid content of 50% and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide-based film HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and heated and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0085] Example 2 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1020 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide substrate HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0086] Example 3 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution, then slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine, and then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1020 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous, then add the nano-silica dispersion to the mixture at a solid content of 125% and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide substrate HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0087] Example 4 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1020 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide substrate CVW-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0088] Example 5 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride (DM-CBDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 940 poise. Stir the obtained polyamic acid mixture with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide substrate HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0089] Example 6 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (TM-CBDA) to react with the diamine. Then, stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 970 poise. Stir the obtained polyamic acid mixture with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then, add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide-based film HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and heated and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0090] Example 7 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (TM-CBDA) to react with the diamine. Then, stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 970 poise. Stir the obtained polyamic acid mixture with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then, add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide-based film HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. Similarly, the precursor liquid was cast onto the other side of the transparent polyimide-based film HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dry composite three-layer film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film material was removed from the oven and analyzed.

[0091] Example 8 The preparation process of the transparent antigenic oxygen polyimide coating is as follows: Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (TM-CBDA) to react with the diamine. Then, stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 970 poise. Stir the obtained polyamic acid mixture with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then, add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The preparation process of the transparent polyimide-based film is as follows: Add 350g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution, then slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine, and then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1620 poise. The polyamic acid mixture obtained above was stirred together with 0.15 mol pyridine and 0.2 mol acetic anhydride until homogeneous. Then, the nano-silica dispersion was added to the mixture at a solid content of 30% and thoroughly mixed until homogeneous. The resulting precursor solution was then cast onto a glass substrate and dried in an oven at 80°C for 20 min to remove some of the solvent. Finally, the semi-dried polyimide film was heated in a nitrogen oven at 300°C for 15 min to complete imidization, with an oxygen concentration of <100 ppm. The resulting polyimide film was then removed from the substrate and analyzed.

[0092] The preparation process of polyimide composite film material is as follows: The obtained precursor liquid was cast onto the above-mentioned transparent polyimide-based film and dried in an oven at 100°C for 10 min to remove some of the solvent; the semi-dried polyimide composite film material was then fixed with a fixture and heated and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm; finally, the obtained polyimide composite film material was removed from the oven and analyzed.

[0093] Example 9 The preparation process of the polyimide film coating is the same as in Example 7; The preparation process of the transparent polyimide-based film is as follows: Add 350g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB). Stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 4,4′-(hexafluoroisopropylidene) phthalic anhydride (6FDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1730 poise. The polyamic acid mixture obtained above was stirred together with 0.15 mol pyridine and 0.2 mol acetic anhydride until homogeneous. Then, the nano-silica dispersion was added to the mixture at a solid content of 30% and thoroughly mixed until homogeneous. The resulting precursor solution was then cast onto a glass substrate and dried in an oven at 80°C for 20 min to remove some of the solvent. Finally, the semi-dried polyimide film was heated in a nitrogen oven at 300°C for 15 min to complete imidization, with an oxygen concentration of <100 ppm. The resulting polyimide film was then removed from the substrate and analyzed.

[0094] The preparation process of polyimide composite film material is as follows: The obtained precursor liquid was cast onto the above-mentioned transparent polyimide-based film and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried polyimide composite film material was then fixed with a fixture and heated and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained polyimide composite film material was removed from the oven and analyzed.

[0095] Comparative Example 1 375 g of N,N-dimethylacetamide solvent was added to a three-necked round-bottom flask, followed by 0.1 mol of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB). The mixture was stirred at room temperature to dissolve the diamine and obtain a clear solution. Then, 0.1 mol of 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (TM-CBDA) was slowly added to react with the diamine. The mixture was then stirred under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 860 poise. The polyamic acid mixture obtained above was stirred evenly with 0.15 mol of pyridine and 0.2 mol of acetic anhydride. Then, a nano-silica dispersion was added to the mixture at 100% solids content and stirred thoroughly until homogeneous. The resin quickly exhibited obvious gelation during the stirring process, and the resin lost its fluidity, preventing further coating experiments.

[0096] Comparative Example 2 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,2-bis[4-(4-aminophenoxybenzene)]propane (BAPP), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 780 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide-based HC-25 film and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film was removed from the oven and analyzed.

[0097] Comparative Example 3 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), and stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.025mol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and 0.075mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine. Then, stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 970 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then, add the nano-silica dispersion to the mixture at 100% solid content and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide-based HC-25 film and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film was removed from the oven and analyzed.

[0098] Comparative Example 4 375 g of N,N-dimethylacetamide solvent was added to a three-necked round-bottom flask, followed by 0.1 mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO). The mixture was stirred at room temperature to dissolve the diamine and obtain a clear solution. Then, 0.1 mol of hydrogenated pyromellitic dianhydride (HPMDA) was slowly added to react with the diamine. The mixture was then stirred under a nitrogen atmosphere for 24-48 hours. A viscous polyamic acid mixture was not prepared, so no further coating experiments were conducted. Comparative Example 5 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution, then slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine, and then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1020 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous, then add the nano-silica dispersion to the mixture at a solid content of 35% and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide substrate HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film was removed from the oven and analyzed.

[0099] Comparative Example 6 Add 375g of N,N-dimethylacetamide solvent to a three-necked round-bottom flask, then add 0.1mol of 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), stir at room temperature to dissolve the diamine and obtain a clear solution. Then, slowly add 0.1mol of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) to react with the diamine. Then stir the mixture under a nitrogen atmosphere for 24-48 hours to obtain a polyamic acid mixture with a viscosity of 1020 poise. Stir the polyamic acid mixture obtained above with 0.15mol of pyridine and 0.2mol of acetic anhydride until homogeneous. Then add the nano-silica dispersion to the mixture at a solid content of 150% and mix thoroughly until homogeneous. The obtained precursor liquid was cast onto a transparent polyimide substrate HC-25 and dried in an oven at 100°C for 10 min to remove some of the solvent. The semi-dried composite film was then fixed with a fixture and cured in a nitrogen oven at 300°C for 10 min with an oxygen concentration of <100 ppm. Finally, the obtained composite film was removed from the oven and analyzed.

[0100] Detection example The thin film performance testing methods are as follows: The transmittance (Tr 550nm), yellowness index, and haze of the polyimide film were tested using an X-rite Ci7800 spectrophotometer. The cross-cut adhesion test is a method of determining the adhesion level of organic coatings to a substrate using a cross-cutting knife. Evaluation method for atomic oxygen resistance: The prepared PI film was tested using a filament discharge plasma-based AO effect simulation device, with an atomic oxygen flux of 1.0 × 10⁻⁶. 21 atom 3 / cm 2 ; The test results of the polyimide-based film are shown in Table 2: Table 2. Test results of polyimide-based films

[0101] The test results of the polyimide composite film material are shown in Table 3: Table 3. Test results of polyimide composite film materials

[0102] According to the test results in the table above, the light transmittance of the polyimide composite film materials in Examples 1 to 9 of this invention is all greater than 88%, the yellow index is all less than 5, the haze is less than 1, and the AO erosion rate is ≤0.031×10⁻⁶. -24 atom / cm 3 Combining excellent optical transmittance and resistance to atomic oxygen erosion, all composite films exhibited superior interfacial adhesion in the cross-cut adhesion test. Furthermore, the prepared films retained good optical transparency after AO erosion, which contributes to the practical application of transparent atomic oxygen polyimide composite film materials in the field of space exploration.

[0103] Meanwhile, according to Comparative Example 1, although TFMB and TM-CBDA can prepare transparent polyamic acid resin, gelation occurred after the resin was added with additives and fillers, preventing further preparation of composite films. In Comparative Example 2, the film prepared by polymerizing BAPP diamine and CBDA had a high yellowness index and poor resistance to AO erosion. In Comparative Example 3, the film prepared by introducing BPDA dianhydride copolymerization had low light transmittance and a yellowness index of 11.2. In Comparative Example 4, HPMDA was used as the dianhydride, and it was found that the monomer had low reactivity, failing to prepare a polyamic acid mixture with a certain viscosity. In Comparative Example 5, when the filler content was reduced to 35%, the atomic oxygen erosion rate of the composite film increased significantly, and the light transmittance of the film decreased significantly after AO irradiation. In Comparative Example 6, when the filler content was increased to 150%, the haze of the composite film deteriorated significantly, and the interfacial adhesion of the composite film also decreased significantly. It is speculated that this was caused by excessive filler content and uneven dispersion.

[0104] Verification of technical effectiveness and / or analysis of technical problem solving As can be seen from the above, the transparent antigenic oxygen polyimide composite film material provided by the present invention is composed of a polyimide film coating and a polyimide base film. The polyimide film coating is made by introducing diamines and dianhydrides with specific structures into the main chain structure of the polyimide film, while adding specific additives and fillers, so that the composite film has both high transmittance and excellent interfacial adhesion performance, as well as excellent resistance to atomic oxygen erosion. The high transparency antigenic oxygen polyimide composite film prepared by the present invention has excellent comprehensive performance and is suitable for flexible optoelectronics, aerospace and other fields, especially as a substrate or protective material for related equipment or devices in the field of space exploration technology.

[0105] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A high-transmittance polyimide film substrate material, characterized in that, Including aromatic phosphorus-containing diamines, alicyclic dianhydride monomers, and organic solvents; The aromatic phosphorus-containing diamine is 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine; the alicyclic dianhydride monomer is selected from at least one of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-cyclobutane-1,2,3,4-tetracarboxylic dianhydride and 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride.

2. The polyimide film substrate material according to claim 1, characterized in that, The organic solvent is selected from at least one of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, γ-butyrolactone, dimethyl sulfoxide, dimethylformamide, m-cresol, ethyl acetate, and acetone.

3. The polyimide film substrate material according to claim 1, characterized in that, The alicyclic dianhydride monomer is 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride.

4. The polyimide film substrate material according to claim 1, characterized in that, The molar ratio of the aromatic phosphorus-containing diamine to the alicyclic dianhydride monomer is 0.95-1:1-1.

1.

5. The polyimide film substrate material according to claim 1, characterized in that, The solid content of the polyimide film substrate is 12wt%-25wt%.

6. A polyimide film coating, characterized in that, include: The polyimide film substrate material and filler according to any one of claims 1-5.

7. The polyimide film coating according to claim 6, characterized in that, The packing material is an inorganic packing material.

8. The polyimide film coating according to claim 6, characterized in that, The mass ratio of the polyimide film substrate material to the filler is 1:0.5-1.

25.

9. The polyimide film coating according to claim 6, characterized in that, The polyimide film coating also contains other auxiliary materials; The other auxiliary materials are at least one of the following: catalyst, dehydrating agent, antioxidant, heat stabilizer, color modifier, antistatic agent, and tear-resistant agent.

10. A polyimide composite film material, characterized in that, include: The polyimide film coating and polyimide-based film according to any one of claims 6-9.

11. The polyimide composite film material according to claim 10, characterized in that, The polyimide composite film material has a two-layer structure of "polyimide film coating - polyimide base film" or a three-layer structure of "polyimide film coating - polyimide base film - polyimide film coating".

12. The polyimide composite film material according to claim 11, characterized in that, The thickness of the polyimide-based film is 12.5-125 μm.

13. The polyimide composite film material according to claim 11, characterized in that, The polyimide composite film material can still achieve a light transmittance of over 80% after atomic oxygen radiation.

14. A method for preparing the polyimide composite film material according to any one of claims 10-13, characterized in that, Including the following steps: S1. Mix aromatic phosphorus-containing diamine and alicyclic dianhydride monomer in an organic solvent and carry out a polymerization reaction to obtain the polyimide film substrate material; S2. The polyimide film substrate material obtained in S1 is mixed with filler and auxiliary materials to obtain the precursor liquid of the polyimide film coating; S3. The precursor liquid obtained in S2 is coated onto the polyimide-based film, and after drying and curing, the polyimide composite film material is obtained.

15. The preparation method according to claim 14, characterized in that, The mixing sequence described in S1 is as follows: first, the aromatic phosphorus-containing diamine is mixed with an organic solvent, and then it is mixed with an alicyclic dianhydride monomer.

16. The preparation method according to claim 14, characterized in that, The polymerization reaction described in S1 takes 24-48 hours and is carried out under an inert atmosphere.

17. The preparation method according to claim 14, characterized in that, The drying temperature described in S3 is 50-180℃; the drying time is 5-60 minutes.

18. The preparation method according to claim 14, characterized in that, The curing method described in S3 is at least one of thermal curing, chemical curing, and combined thermochemical curing.

19. The preparation method according to claim 18, characterized in that, S3 describes a curing method of nitrogen oven thermal curing; Furthermore, the curing method described in S3 is heat curing in a nitrogen oven with an oxygen concentration of <100ppm.

20. The preparation method according to claim 14 or any one of claims 18-19, characterized in that, The thermosetting temperature is 250-350℃; the duration is 5-60 minutes.

21. The application of the polyimide composite film material according to any one of claims 10-13 in the fields of flexible optoelectronics and aerospace.

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