Preparation method for high-performance polyimide and application thereof

Abstract

The present application relates to the technical field of polyimides and relates to a preparation method for a high-performance polyimide and an application thereof, aiming to solve the problems in the prior art such as numerous side reactions and severe impact on transparency caused by an excessively high imidization reaction temperature during the use of a high-temperature thermal imidization method for the preparation of polyimides. The preparation method comprises: (1) preparing a polyamic acid solution; (2) adding a chemical catalyst and a polyamic acid solution to partially complete an imidization reaction; (3) adding an end group auxiliary agent, performing coating with the solution, heating, and maintaining the heat to complete the imidization reaction; and (4) carrying out high-temperature treatment to obtain a high-performance polyimide. The present application can significantly reduce numerous side reactions present in a traditional imidization reaction, eliminate an adverse effect of high-temperature imidization on the optical performance, greatly improve the mechanical properties, heat resistance, optical performance, etc. of a material, and also achieve both high heat resistance and high transparency.

Description

High-performance preparation method and application of polyimide TECHNICAL FIELD

[0001] The present application relates to the technical field of polyimide, and particularly relates to a high-performance preparation method and application of polyimide. BACKGROUND

[0002] Polyimide has excellent heat resistance, mechanical properties, insulation and other properties, is one of the highest temperature-resistant special polymer materials in practical application, plays an irreplaceable role in many extreme environment fields, and is widely used in the fields of aviation, aerospace, electrical, electronic and microelectronic, and is known as the "problem solver". The preparation process of polyimide usually includes two steps: polymerization reaction of diamine and dianhydride monomer to generate polyamide acid, and then imidization reaction to complete dehydration ring closure to obtain polyimide. According to different imidization methods, it can be roughly divided into chemical imidization method and thermal imidization method, and the process conditions and application range of the two methods are significantly different. ① Chemical imidization method: the imidization reaction is completed by adding chemical dehydrating agent and catalytic aid in polyamide acid, which is suitable for polyimide systems with good solubility, and cannot be applied to more extensive non-soluble systems; ② Thermal imidization method: the imidization reaction is completed by high-temperature heat treatment without external imidization aid, which has no requirement for the solubility of the final product and is suitable for all types of polyimide systems.

[0003] The thermal imidization method has wide applicability and simple process conditions, and is widely used in the processing and preparation of various polyimide materials, especially the most widely used non-soluble systems of uniform benzene and biphenyl. Taking polyimide film as an example, the polyamide acid solution is usually spin-coated or flow-coated into a wet film, and then the high-temperature imidization reaction is completed by gradually increasing the temperature after pre-baking. In order to realize complete imidization of polyamide acid, the preparation temperature of thermal imidization method should be higher than the glass transition temperature of polyimide in theory, and the rigid structure system often needs to be above 350 DEG C or even 400 DEG C. Such high imidization temperature brings many challenges, and the most prominent problem is that many side reactions occur in the high-temperature imidization process, including the thermal inverse depolymerization reaction of polyamide acid leading to the decrease of molecular weight, the amide reaction of amine group and carboxyl group leading to the formation of branched structure, the intermolecular dehydration reaction leading to the formation of cross-linked structure, etc., which seriously affects the final performance of polyimide material, especially the decrease of mechanical properties, heat resistance and optical properties, and poor performance stability. Especially in the application of optical display, high-temperature imidization also has adverse effects on the optical properties of polyimide film, leading to deepening of film color and decrease of transparency, which greatly limits the high-performance preparation of transparent polyimide material and its more extensive application. SUMMARY

[0004] In view of the above analysis, the present application aims to provide a simple and versatile high-performance preparation method and application of polyimide, which can at least solve one of the following technical problems: (1) the existing technology adopts thermal imidization method to prepare polyimide, which has many side reactions and is difficult to achieve high-performance preparation; (2) the existing chemical imidization method cannot be applied to more extensive non-soluble systems for good soluble polyimide systems, and the operation process is more complicated, so the application is greatly limited; (3) the existing high-temperature imidization process conditions are difficult to achieve high heat resistance and high transparency when preparing high-temperature-resistant polyimide with a glass transition temperature (T g ) greater than 400℃, and the high imidization temperature seriously affects the optical transparency and causes the color of the film to deepen.

[0005] The purpose of the present application is mainly realized by the following technical solutions:

[0006] In a first aspect, the present application provides a high-performance preparation method of polyimide, comprising the following steps:

[0007] Step 1: reacting diamine monomers with dianhydride monomers to obtain a polyamide acid solution;

[0008] Step 2: adding a chemical catalyst, and completing a partial imidization reaction of the polyamide acid solution;

[0009] Step 3: adding an end group aid, coating the solution into a film, and completing the imidization reaction by heating and keeping warm;

[0010] Step 4: high-temperature treatment to obtain high-performance polyimide;

[0011] In steps 2 and 3, the imidization reaction temperature is below 250℃.

[0012] Optionally, in step 2, the reaction temperature is 40-130℃, and the imidization reaction degree of the polyamide acid is 20%-70%.

[0013] Optionally, in step 3, the heating temperature is 150-250℃, and the imidization reaction degree of the polyamide acid is 85%-100%.

[0014] Optionally, in step 2, the chemical catalyst is a basic catalyst containing a nitrogen atom.

[0015] Optionally, the chemical catalyst is one or more of imidazole, quinoline, pyridine imine type compounds, or piperidine, piperazine, alkyl tertiary amine type compounds.

[0016] Optionally, in step 3, the end group coagent is one or more of a monofunctional anhydride compound, including phthalic anhydride, 3-fluorophthalic anhydride, 4-fluorophthalic anhydride, 3,4,5,6-tetrafluorophthalic anhydride, naphthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, maleic anhydride, dimethyl maleic anhydride, acetic anhydride, trifluoroacetic anhydride, propionic anhydride, succinic anhydride.

[0017] Optionally, in step 1, the diamine monomer includes at least one of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethoxy-4,4'-diaminobiphenyl, 1,4-cyclohexanediamine, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3',5,5'-tetramethylbenzidine, 2,2-bis[3-(3-aminobenzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2-bis[l-(4-aminobenzoyl)-4-aminophenyl]hexafluoropropane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis(trifluoromethyl)-4,4'-diaminophenyl ether, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, 4-aminobenzoic acid-4'-aminophenyl ester, [4-(4-aminobenzoyl)oxyphenyl] 4-aminobenzoate, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)-4,4'-bis(4-aminophenylcarbonylaminobiphenyl), 2,2'-bis(trifluoromethyl)-4,4'-diaminobenzanilide, 2-(4-aminophenyl)-5-aminobenzoxazole, 2-(4-aminophenyl)-5-aminobenzimidazole, and 9,9-dimethylfluorene-2,7-diamine.

[0018] Optionally, in step 1, the dianhydride monomer comprises at least one of 1,2,4,5-benzene-tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthrene tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, bicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 2,5,7,10-hydrogenated naphthalene tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 4,4-hexafluoroisopropyl phthalic anhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, cyclopentanone bis-spiro norbornane dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, N-[4-[4-[(1,3-dioxo-2-benzofuran-5-carbonyl)amino]-2-(trifluoromethyl)phenyl]-3-(trifluoromethyl)phenyl]-1,3-dioxo-2-benzofuran-5-carboxamide, 1,4-phenylene-benzene-trimesate dianhydride, and 3,3',4,4'-diphenyl benzoic acid terephthalamide tetracarboxylic dianhydride.

[0019] Optionally, in step 3, the holding time is 0.5-6 hours.

[0020] Optionally, in step 1, the molar ratio of the diamine monomer to the dianhydride monomer is 1:(0.95-0.99).

[0021] Optionally, in step 2, the molar ratio of the chemical catalyst to the diamine monomer is (0.2-2):1.

[0022] Optionally, in step 3, the molar ratio of the end group auxiliary agent to the diamine monomer is (0.05-0.60):1.

[0023] Optionally, in step 4, the temperature of the high-temperature treatment is 380-450℃, and the high-temperature treatment time is 20 min-4 h.

[0024] In a second aspect, the application further provides an application of the above preparation method in the fields of electrical, electronic, microelectronic, display, and communication.

[0025] Compared with the prior art, the application can at least achieve one of the following beneficial effects:

[0026] (1) Compared with the traditional high-temperature thermal imidization method, the present application improves the preparation process, i.e. adding a chemical catalyst → adding an end group auxiliary agent → coating a film → heating → high-temperature treatment, so that the entire imidization of polyamic acid can be completed at a low temperature (< 250℃, the existing technology is 350℃ or even above 400℃), which can effectively avoid the reversible reaction and various side reactions occurring in the high-temperature imidization process, and overcome the difficulty in simultaneously achieving high heat resistance and high transparency of polyimide under the existing high-temperature imidization process conditions. In particular, when preparing a high-temperature-resistant polyimide with a glass transition temperature (T g ) greater than 400℃, the excessively high imidization temperature has an adverse effect on the optical properties of the high-temperature-resistant polyimide, while the present technical solution can simultaneously improve the heat resistance, mechanical properties and optical properties of the polyimide, and high-performance high-temperature-resistant polyimide can be prepared through simple process conditions (see Table 1).

[0027] (2) The present application optimizes the overall process of the imidization reaction through the process method combining a chemical catalyst with high-temperature treatment, which not only greatly improves the imidization degree in the low-temperature range and induces the orientation arrangement of the molecular chain, but also further improves the close packing of the polymer molecular chain through high-temperature heat treatment, eliminates the negative effects that the added auxiliary agent may have, makes the aggregate structure of the film more stable, and further improves the mechanical properties and high-temperature optical properties of the polyimide, and the high-temperature treatment is also beneficial to the release of thermal stress generated during the preparation of the material.

[0028] (3) The present application adds an end group auxiliary agent to play the following roles: first, it can deactivate the active end amino group in the polyimide molecular chain, avoiding the oxidative reaction or depolymerization side reaction of the active group at high temperature, which is helpful to obtain a transparent polyimide resistant to high-temperature yellowing; second, after a certain degree of imidization is obtained under the action of chemical catalysis, the addition of the end group auxiliary agent can reduce the adverse effects on the growth of the polymer molecular weight, which is helpful to obtain a high-molecular-weight polymer, thereby improving the heat resistance, mechanical properties, etc. of the polyimide; third, it can fully exert the synergistic effect of the anhydride-based end group auxiliary agent on the chemical catalyst, promote the chemical catalysis effect under high-temperature conditions, and inhibit the negative effects of the catalyst at high temperature, thereby obtaining a high-performance polyimide with excellent heat resistance, mechanical properties and optical transparency.

[0029] (4) The present application controls the imidization reaction degree through two stages of solution phase (step 2) and gel solution film baking (step 3), the first stage is 20% to 70%, and the second stage is 85% to 100%, which is beneficial to obtain a high-molecular-weight polymer (improve the mechanical properties of the polyimide), and the catalysis can be used to induce the molecular chain at a relatively low temperature, realize effective regulation of the aggregate structure, and at the same time, the reaction system will not be gel-like, which is beneficial to processing and molding.

[0030] (5) Compared with the traditional chemical imidization method, the preparation method of the application is simpler and more universal, which has no requirement for the solubility of the polyimide system, and eliminates the complicated processing process caused by the combination of the catalyst and the dehydrating agent in the past.

[0031] (6) Compared with the traditional thermal imidization method, the preparation method of the application is simple, and the imidization reaction can be completed at a lower temperature through appropriate additives and process conditions to obtain a high imidization degree, and then high-performance polyimide is prepared by high-temperature treatment.

[0032] In the application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent description, and some advantages will become apparent from the description, or will be understood by implementing the application. The purpose and other advantages of the application can be achieved and obtained from the content specifically pointed out in the description. DETAILED DESCRIPTION

[0033] In the first aspect, the application provides a high-performance preparation method of polyimide, comprising the following steps:

[0034] Step 1: reacting diamine monomers and dianhydride monomers to prepare a polyamide acid solution;

[0035] Step 2: adding a chemical catalyst, and completing a partial imidization reaction of the polyamide acid solution;

[0036] Step 3: adding an end group additive, coating the solution into a film, and completing the imidization reaction by heating and keeping warm;

[0037] Step 4: high-temperature treatment to obtain high-performance polyimide.

[0038] Specifically, in step 1, the diamine monomers and the dianhydride monomers undergo polycondensation reaction in an organic solvent to generate polyamide acid, and the molar ratio of the diamine to the dianhydride is 1:(0.95-0.99), for example, 1:0.95, 1:0.96, 1:0.97, 1:0.98, or 1:0.99. This is because: when the molar ratio of the diamine to the dianhydride is close to 1:1, it is helpful to obtain polyimide with high molecular weight, and the greater the difference, the less favorable it is.

[0039] In one embodiment, the diamine monomer and the dianhydride monomer can be one or more of aromatic, alicyclic, semi-aromatic, semi-alicyclic, spirocyclic, amide-containing, ester-containing diamine or dianhydride. To prepare a polyimide having high heat resistance and high transparency, the diamine is preferably at least one of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethoxy-4,4'-diaminobiphenyl, 1,4-cyclohexanediamine, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3',5,5'-tetramethylbenzidine, 2,2-bis[3-(3-aminobenzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2-bis[1-(4-aminobenzoyl)-4-aminophenyl]hexafluoropropane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis(trifluoromethyl)-4,4'-diaminophenyl ether, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, 4-aminobenzoic acid-4'-aminophenyl ester, [4-(4-aminobenzoyl)oxyphenyl] 4-aminobenzoate, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)-4,4'-bis(4-aminophenylcarboxamidyl)biphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobenzanilide, 2-(4-aminophenyl)-5-aminobenzoxazole, 2-(4-aminophenyl)-5-aminobenzimidazole, 9,9-dimethylfluorene-2,7-diamine.

[0040] The dianhydride is preferably at least one of 1,2,4,5-benzene tetra carboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 9,9-bis(trifluoromethyl)-2,3,6,7-oxanaphthacene tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, bicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 2,5,7,10-hydrogenated naphthalene tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 4,4-hexafluoroisopropyl phthalic anhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, cyclopentanone bispinanediol dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, N-[4-[4-[(1,3-dioxo-2-benzofuran-5-carbonyl)amino]-2-(trifluoromethyl)phenyl]-3-(trifluoromethyl)phenyl]-1,3-dioxo-2-benzofuran-5-carboxamide, 1,4-phenylene-bisphenyltrimellitimide dianhydride, and 3,3',4,4'-benzophthalic terephthalamide tetracarboxylic dianhydride.

[0041] The structures of the diamine and the dianhydride can be selected according to the requirements of transparency, heat resistance, and the like of the polyimide film, and one diamine and one dianhydride can be used for homopolymerization, or one diamine and a plurality of dianhydrides, or a plurality of diamines and one dianhydride, or a plurality of diamines and a plurality of dianhydrides can be used for copolymerization according to the performance requirements.

[0042] Specifically, in step 1, the reaction temperature of the diamine monomer and the dianhydride monomer is -10 to 60°C, for example, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C.

[0043] The specific reaction temperature is related to the activity of the diamine monomer and the dianhydride monomer. When the diamine monomer and the dianhydride monomer have good activity, it is advantageous to have a reaction temperature < 30°C. This is because the polyamic acid synthesis reaction is an exothermic reaction, and thus a low temperature is conducive to the forward progress of the polyamic acid reaction. When the activity of the diamine monomer and the dianhydride monomer is low, a reaction temperature of 30 to 60°C is advantageous for the reaction, and a too low reaction temperature is not conducive to the forward progress of the polyamic acid reaction.

[0044] Specifically, in step 1, the solid content of the polyamic acid solution is 5wt% to 30wt%, for example, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%. The viscosity of the polyamic acid solution is 1500 to 300000 mPa·s, for example, 1500 mPa·s, 5000 mPa·s, 10000 mPa·s, 15000 mPa·s, 20000 mPa·s, 25000 mPa·s, 30000 mPa·s, 50000 mPa·s, 100000 mPa·s, 150000 mPa·s, 200000 mPa·s, 250000 mPa·s, 300000 mPa·s.

[0045] Specifically, in step 2, the chemical catalyst is a basic catalyst containing a nitrogen atom, and the basicity value (pK b ) is 2.0 to 14.0, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0. The basicity value is preferably 4.0 to 9.0.

[0046] In step 2, the boiling point of the chemical catalyst is 60 to 280℃, for example, 60℃, 80℃, 100℃, 120℃, 130℃, 150℃, 180℃, 200℃, 220℃, 240℃, 260℃. Preferably, 130 to 260℃.

[0047] Specifically, the chemical catalyst in step 2 can be a single component or a plurality of components used in combination; the molar ratio of the chemical catalyst to the diamine monomer is (0.2 to 2) : 1, for example, 0.2:1, 0.3:1, 0.5:1, 0.6:1, 0.8:1, 1.0:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2.0:1.

[0048] The chemical catalyst used is a nitrogen-containing basic compound with moderate basicity, which can be one or more of imidazole, quinoline, pyridine, or other imine type compounds, or one or more of piperidine, piperazine, alkyl tertiary amine type compounds. Preferably, one or more of piperazine, methyl piperazine, dimethyl piperazine, imidazole, methyl imidazole, dimethyl imidazole, pyridine, methyl pyridine, dimethyl pyridine, quinoline, methyl quinoline, dimethyl quinoline, isoquinoline, piperidine, triethylene diamine, triethylamine. The structure and type of the chemical catalyst are mainly considered according to the structural characteristics of the polyimide, such as rigidity and flexibility, and the requirements of the imidization process.

[0049] The addition of the chemical catalyst can help to improve the imidization reaction rate and degree of the polyamic acid. If the basicity of the chemical catalyst is too low, i.e. the alkalinity value is large, the catalytic effect on the imidization reaction is poor, especially under the condition of low addition amount and low temperature, the improvement of the imidization degree is not obvious; if the basicity is too strong, the chemical catalyst is easy to form a polyamic acid salt with poor solubility with the polyamic acid, and a high molecular weight polyimide film cannot be obtained, which seriously affects the heat resistance, mechanical properties, processability and other properties of the material. In addition, if the boiling point of the chemical catalyst is too low, the catalyst may be removed too quickly during the heating process, and the imidization reaction cannot be effectively catalyzed.

[0050] In addition, if the addition amount of the chemical catalyst is too much, the chemical catalyst is easy to form a polyamic acid salt with poor solubility with the polyamic acid, and a high molecular weight polyimide film cannot be obtained, which seriously affects the heat resistance, mechanical properties, processability and other properties of the material. If the addition amount of the chemical catalyst is too small, the catalytic effect on the imidization reaction is poor, especially under the condition of low addition amount and low temperature, the improvement of the imidization degree is not obvious. Controlling the molar ratio of the chemical catalyst to the diamine monomer to be (0.2-2):1 can achieve good catalytic effect, and the formation of a polyamic acid salt with poor solubility can be avoided, so that a high molecular weight polyimide can be obtained, and a high-performance polyimide with good heat resistance, mechanical properties, processability and other properties can be obtained.

[0051] Specifically, in step 2, the reaction temperature is 40-130°C, and the reaction time is 1-6h. The reaction temperature may be, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C. The reaction time may be, for example, 1h, 2h, 3h, 4h, 5h, 6h.

[0052] Specifically, in step 2, the imidization degree of the polyamic acid is 20%-70%, for example, 20%, 30%, 40%, 50%, 60%, 70%.

[0053] The imidization degree in step 2 is too low (<20%), and the effect of regulating the aggregate structure is not obvious; if the imidization degree is too high (>70%), the solution of the partially imidized polyamic acid may become turbid or even gel-like due to poor solubility, which is not conducive to subsequent processing and molding, and the surface quality and optical properties of the material may be affected. Controlling the pre-imidization degree to be 20%-70% can achieve good effect of regulating the aggregate structure, and the reaction system will not become gel-like, which is conducive to subsequent processing and molding.

[0054] Specifically, the imidization degree can be controlled by adjusting the reaction temperature and the reaction time jointly. The higher the imidization degree of the polyamic acid solution, the more polyamic acid is converted into polyimide. The imidization degree can be tested by infrared spectroscopy, nuclear magnetic resonance and thermal decomposition method.

[0055] Specifically, in step 3, the temperature is 150-250℃, for example, 150℃, 170℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃; the heating rate is 1-5℃ / min, for example, 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min. The holding time is 0.5-6 hours, for example, 0.5h, 1h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h.

[0056] The present application completes the dehydration and ring-closing reaction of amide acid at a lower temperature through low-temperature catalysis of a chemical catalyst, and ensures that the imidization reaction of polyamide acid is basically or completely completed by using chemical catalysis in solution and second-stage chemical catalysis after molding (adding end-group auxiliary agent and then heating in step 3), so that the degree of imidization of polyamide acid reaches 85%-100%.

[0057] Specifically, the end-group auxiliary agent in step 3 is a monofunctional anhydride compound, and the molar ratio of the end-group auxiliary agent to the diamine monomer is (0.05-0.60) : 1, for example, 0.05:1, 0.06:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1.

[0058] The monofunctional anhydride compound can be one or more of aromatic, alicyclic, and aliphatic monoanhydride. Preferably, it is one or more of phthalic anhydride, 3-fluorophthalic anhydride, 4-fluorophthalic anhydride, 3,4,5,6-tetrafluorophthalic anhydride, naphthalene anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, maleic anhydride, dimethyl maleic anhydride, acetic anhydride, trifluoroacetic anhydride, propionic anhydride, and succinic anhydride. The structure and type of the end-group auxiliary agent are selected in consideration of the basicity value and residual amount of the chemical catalyst, and according to the requirements of transparency and heat resistance of the material.

[0059] It should be noted that the polyamide acid can achieve high imidization degree or even complete imidization at a lower temperature (<250℃) through chemical catalysis. On this basis, the addition of the end-group auxiliary agent can reduce the adverse effect of the monofunctional auxiliary agent on the molecular weight growth of the polymer, and help to obtain a high-molecular-weight polymer; on the other hand, it can fully exert the synergistic effect of the anhydride end-group auxiliary agent on the chemical catalyst, promote the chemical catalysis effect under high-temperature conditions, and inhibit the negative effect of the catalyst under high temperature.

[0060] Specifically, in step 4, the temperature of high-temperature treatment is higher than the glass transition temperature (Tg) of the polyimide, for example, 250-350℃, for example, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃. g) above 10-50℃, considering the T g The temperature of the high-temperature treatment is preferably 380-450℃, for example, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃. The high-temperature treatment time is 20 min-4 h, for example, 20 min, 40 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h.

[0061] The high-temperature treatment stage is crucial for adjusting the aggregate structure of the material. Suitable high-temperature treatment is helpful for further inducing the close packing of the molecular chains through high temperature on the basis of the orientation and arrangement of the molecular chains induced by the chemical catalyst, and eliminating the negative effects of the small molecule additives. In addition, the high-temperature treatment is also conducive to the release of the thermal stress generated in the process of preparing the material. The temperature of the high-temperature treatment is preferably above the glass transition temperature of the material.

[0062] Further, when the preparation of the polyimide film material is performed in step 3 or step 4, a unidirectional or bidirectional stretching process can be adopted to help the further orientation of the polymer molecular chains in the film, increase the content of the ordered packing components, and improve the heat resistance, dimensional stability and the like of the film.

[0063] In addition, the thermal imidization stage and the high-temperature treatment stage can be performed in a vacuum, air or oxygen-free environment. From the perspective of the optical transparency of the material, the imidization reaction or the high-temperature treatment is performed in a vacuum and oxygen-free environment.

[0064] In a second aspect, the application provides a method for preparing high-performance polyimide materials in the fields of electrical, electronic, microelectronic, display, communication, and the like, which is suitable for the preparation of high-performance polyimide products including films, coatings, resins and the like.

[0065] The application will be further described below in combination with specific examples, but the application is not limited to the following examples. In the following examples, representative diamines, dianhydrides, chemical catalysts and end-group additives are selected, and high-performance polyimide films of different structures are synthesized by using the preparation method provided by the application. The diamine and / or dianhydride monomer and / or chemical catalyst and end-group additive in the examples are replaced by other types described in the content of the application, and the polyimide film, coating or other form product prepared by using the technical method and conditions provided by the application all have the same similar effect as the examples.

[0066] In the application, the percentage content and percentage concentration are mass percentage content and mass percentage concentration unless otherwise specified. The raw materials can be obtained from commercial public channels unless otherwise specified. The film thickness in the examples can be controlled by the type of coating roll and the solid content of the polyamic acid solution.

[0067] Example 1

[0068] (1) Into a three-necked flask equipped with a mechanical stirrer, nitrogen inlet and outlet, and a thermometer, 64.05 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl and 400 g of N-methylpyrrolidone were added under inert gas protection, and stirred until completely dissolved. The temperature was lowered to 10°C, 41.88 g of pyromellitic dianhydride and 200 g of N-methylpyrrolidone were added, and stirred for 24 hours after complete dissolution. The solution was diluted with solvent according to the viscosity of the system, and a polyamic acid solution with a viscosity of 13000 mPa-s was obtained.

[0069] (2) 6.81 g of imidazole was added to the polyamic acid solution obtained in step 1, and stirred at 60°C for 2 hours. After sampling and coating, it was dried and tested for imidization degree (ID) by infrared spectroscopy. The imidization degree was calculated according to the formula, taking the imide ring vibration peak at 1380 cm -1 as the judgment standard and the benzene ring vibration peak at 1500 cm -1 as the normalization standard. The imidization degree was 38%.

[0070] (A is the absorbance or peak area of the absorption peak)

[0071] (3) 3.08 g of hexahydrophthalic anhydride was added to the solution obtained in step 2, and stirred at room temperature for 4 hours to obtain a partially imidized and end group treated polyamic acid solution. The above solution was coated on a dry glass plate with a smooth surface by a casting method, and was placed in an oven and subjected to temperature rising and holding treatment under nitrogen atmosphere. The specific process was as follows: 200°C / 1 hour, 250°C / 1 hour. After cooling, the imidization degree (ID) was tested to be 92%.

[0072] (4) The glass plate carrying the polyimide film obtained in step 3 was heated to 420°C in a high temperature oven for 1 hour to obtain the final film; or the glass plate carrying the polyimide film was cooled to room temperature and immersed in deionized water, the film was automatically peeled off and dried, and then it was laid on a metal support frame and fixed around, and placed in a high temperature oven at 420°C for 1 hour to complete the high temperature treatment. The film was named HPI-1, with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0073] Example 2

[0074] (1) Into a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and outlet, and a thermometer, 64.05 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl and 320 g of N-methylpyrrolidone were added under inert gas protection, and stirred until completely dissolved. The temperature was lowered to 15°C, 28.54 g of biphenyltetracarboxylic dianhydride, 21.16 g of pyromellitic dianhydride and 200 g of N-methylpyrrolidone were added, and stirred for 36 hours after completely dissolved. Solvent was added for dilution according to the viscosity of the system, and a polyamic acid solution with a viscosity of 16000 mPa-s was obtained.

[0075] (2) 27.23 g of imidazole was added to the polyamic acid solution obtained in step 1, and stirred at 70°C for 3 hours. After sampling and coating a film, the imidization degree (ID) was tested to be 51%.

[0076] (3) 13.20 g of 3,4,5,6-tetrafluorophthalic anhydride was added to the solution obtained in step 2, and stirred at room temperature for 3 hours to obtain a partially imidized and end group treated polyamic acid solution. The above solution was coated on a dry glass plate with a smooth surface by a casting method, and was subjected to temperature elevation and holding treatment in an oven under nitrogen atmosphere. The specific process was as follows: 160°C / 1 hour, 250°C / 1 hour. After cooling, the imidization degree (ID) was tested to be 90%.

[0077] (4) The glass plate with the polyimide film obtained in step 3 was subjected to high temperature treatment at 400°C for 1 hour in a high temperature oven, and was immersed in deionized water after cooling to room temperature. The film was automatically peeled off and dried to obtain a final film. The film was named as HPI-2, and the film thickness was 10±2 micrometers. The main properties are shown in Table 1.

[0078] Example 3

[0079] (1) Into a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet and outlet, and a thermometer, 64.05 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl and 320 g of N-methylpyrrolidone were added under inert gas protection, and stirred until completely dissolved. The temperature was lowered to 15°C, 28.54 g of biphenyltetracarboxylic dianhydride, 21.16 g of pyromellitic dianhydride and 200 g of N-methylpyrrolidone were added, and stirred for 36 hours after completely dissolved. Solvent was added for dilution according to the viscosity of the system, and a polyamic acid solution with a viscosity of 16000 mPa-s was obtained.

[0080] (2) 27.23 g of imidazole was added to the polyamic acid solution obtained in step 1, and stirred at 70°C for 3 hours. After sampling and coating a film, the imidization degree (ID) was tested to be 51%.

[0081] (3) To the solution obtained in step 2, 13.29 g of 3-fluorophthalic anhydride was added, and stirred at room temperature for 3 hours to obtain a partially imidized and end-group treated polyamic acid solution; the above solution was coated on a dry glass plate with smooth surface by a flow coating method, and placed in an oven for temperature rising and holding under nitrogen atmosphere. The specific process was as follows: 230°C / 2 hours. After cooling, the imidization degree (ID) of the product was 87%.

[0082] (4) The glass plate with polyimide film obtained in step 3 was heated to 380°C in a high temperature oven for 1 hour and to 410°C for 30 minutes, and then soaked in deionized water after cooling to room temperature, automatically peeled off and dried to obtain the final film. The film was named HPI-3, with a thickness of 10±2 microns, and the main properties were shown in Table 1.

[0083] Example 4

[0084] (1) Under inert gas protection, 64.05 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl and 320 g of N-methylpyrrolidone / N,N-dimethylformamide mixed solvent (volume ratio 3:1) were added into a three-necked flask equipped with mechanical stirring, nitrogen inlet and outlet and thermometer, and stirred until completely dissolved. After cooling to 25°C, 17.41 g of 4,4'-hexafluoroisopropyl phthalic anhydride, 34.20 g of pyromellitic dianhydride and 200 g of N-methylpyrrolidone / N,N-dimethylformamide mixed solvent (volume ratio 3:1) were added, and stirred for 48 hours after completely dissolved. According to the viscosity of the system, the solvent was diluted to obtain a polyamic acid solution with a viscosity of 11000 mPa·s.

[0085] (2) To the polyamic acid solution obtained in step 1, 11.87 g of pyridine and 10.21 g of imidazole were added, and stirred at 90°C for 1.5 hours. The imidization degree (ID) of the product was 57% after coating film and testing.

[0086] (3) To the solution obtained in step 2, 10.01 g of succinic anhydride was added, and stirred at room temperature for 2 hours to obtain a partially imidized and end-group treated polyamic acid solution; the above solution was coated on a dry glass plate with smooth surface by a flow coating method, and placed in an oven for temperature rising and holding under nitrogen atmosphere. The specific process was as follows: 250°C / 2 hours. After cooling, the imidization degree (ID) of the product was 95%.

[0087] (4) The glass plate with polyimide film obtained in step 3 was heated to 400°C in a high temperature oven for 1 hour and to 420°C for 20 minutes, and then soaked in deionized water after cooling to room temperature, automatically peeled off and dried to obtain the final film. The film was named HPI-4, with a thickness of 10±2 microns, and the main properties were shown in Table 1.

[0088] Example 5

[0089] (1) Under inert gas protection, a three-necked flask equipped with mechanical stirring, nitrogen inlet and outlet and a thermometer was charged with 14.53 g of 2,2'-bis(trifluoromethyl)-4,4'-diaminobenzanilide, 51.24 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl and 400 g of N-methylpyrrolidone, and stirred until completely dissolved. The temperature was lowered to 45°C, 41.44 g of pyromellitic dianhydride and 380 g of N-methylpyrrolidone were added, and after complete dissolution, stirring was carried out for 32 hours. Solvent dilution was carried out according to the viscosity of the system, and a polyamic acid solution with a viscosity of 18000 mPa·s was obtained.

[0090] (2) To the polyamic acid solution obtained in step 1, 25.83 g of quinoline and 13.62 g of imidazole were added, and stirring was carried out at 120°C for 1 hour. After sampling and coating, the imidization degree (ID) of the film was tested to be 61%.

[0091] (3) To the solution obtained in step 2, 30.63 g of acetic anhydride and 44.44 g of methyltetrahydrophthalic anhydride were added, and stirring was carried out at room temperature for 4 hours to obtain a partially imidized and end group treated polyamic acid solution. The above solution was coated onto a dry glass plate with a smooth surface by a casting method, and was placed in an oven and subjected to temperature rising and holding treatment under a nitrogen atmosphere. The specific process was: 250°C / 2 hours. After cooling, the imidization degree (ID) of the film was tested to be 88%.

[0092] (4) The glass plate loaded with the polyimide film obtained in step 3 was subjected to high temperature treatment in a high temperature oven at 410°C for 1 hour and at 430°C for 15 minutes, and after cooling to room temperature, was immersed in deionized water, automatically peeled off and dried to obtain a final film. The film was named HPI-5, with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0093] Comparative Example 1a

[0094] (1) Under inert gas protection, a three-necked flask equipped with mechanical stirring, nitrogen inlet and outlet and a thermometer was charged with 64.05 g of 2,2'-bis(trifluoromethyl)diaminobiphenyl and 400 g of N-methylpyrrolidone, and stirred until completely dissolved. The temperature was lowered to 10°C, 41.88 g of pyromellitic dianhydride and 200 g of N-methylpyrrolidone were added, and after complete dissolution, stirring was carried out for 24 hours. Solvent dilution was carried out according to the viscosity of the system, and a polyamic acid solution with a viscosity of 13000 mPa·s was obtained.

[0095] (2) The polyamic acid solution obtained in step 1 was coated onto a dry glass plate with a smooth surface by a casting method, and was subjected to film baking treatment in an oven under a nitrogen atmosphere using a conventional thermal imidization process, with the following specific process: 80°C / 1 hour, 200°C / 1 hour, 350°C / 1 hour.

[0096] (3) After the glass plate with the polyimide film obtained in step 2 was cooled to room temperature, it was immersed in deionized water, the film was automatically peeled off and dried to prepare a conventional high-temperature imidized RPI-1a film with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0097] Comparative Example 1b

[0098] This comparative example is basically the same as Example 1, except that in step 2, after the addition of imidazole, the reaction was stirred at 30°C for 2 hours, and after sampling and coating, the film was dried at room temperature, and the imidization degree (ID) was only 13%; in addition, in step 3, the heating and holding treatment conditions were changed to: 300°C / 1 hour. The obtained film was named RPI-1b, with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0099] Comparative Example 2a

[0100] This comparative example is basically the same as Comparative Example 1a, except that the dianhydride monomer was replaced by a mixed component of 3,3',4,4'-biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride (molar ratio 1:1), and other synthesis conditions such as the molar ratio of diamine to dianhydride, the type and amount of solvent, and the film baking process were the same. A conventional high-temperature imidized RPI-2a film was prepared, with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0101] Comparative Example 2b

[0102] This comparative example is basically the same as Example 2, except that in step 2, 40.85g of imidazole was added to the polyamic acid solution, and the reaction was stirred at 70°C for 3 hours. After sampling and coating, the film was dried at room temperature, and the imidization degree (ID) was 75%. The obtained film was named RPI-2b, with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0103] Comparative Example 3a

[0104] This comparative example is basically the same as Comparative Example 1a, except that the dianhydride monomer was replaced by a mixed component of 3,3',4,4'-biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride (molar ratio 3:7), and other synthesis conditions such as the molar ratio of diamine to dianhydride, the type and amount of solvent, and the film baking process were the same. A conventional high-temperature imidized RPI-3a film was prepared, with a thickness of 10±2 microns, and the main properties are shown in Table 1.

[0105] Comparative Example 3b

[0106] This comparative example is essentially the same as Example 3, except that in Step 3, 26.58 g of 3-fluorophthalic anhydride was added to the solution and stirred at room temperature for 3 hours to obtain a partially imidized and end-group treated polyamic acid solution. The film prepared thereafter was designated as RPI-3b, with a thickness of 10 ± 2 micrometers, and the main properties are shown in Table 1.

[0107] Comparative Example 4a

[0108] This comparative example is essentially the same as Comparative Example la, except that the dianhydride monomer was replaced by a mixed component of 4,4'-hexafluoroisopropyl phthalic anhydride and pyromellitic dianhydride (molar ratio 2:8), and other synthesis conditions such as the molar ratio of diamine to dianhydride, the type and amount of solvent, and the film baking process were the same. A conventional high-temperature imidized RPI-4a film was prepared, with a thickness of 10 ± 2 micrometers, and the main properties are shown in Table 1.

[0109] Comparative Example 4b

[0110] This comparative example is essentially the same as Example 4, except that in Step 2, no chemical catalyst was added to the polyamic acid solution, and the reaction was also stirred at 90°C for 1.5 hours. The imidization degree was not tested, and other synthesis conditions and film preparation processes were the same. The obtained film was designated as RPI-4b, with a thickness of 10 ± 2 micrometers, and the main properties are shown in Table 1.

[0111] Comparative Example 5a

[0112] This comparative example is essentially the same as Comparative Example la, except that the diamine monomer was replaced by a mixed component of 2,2'-bis(trifluoromethyl)-4,4'-diaminobenzanilide and 2,2'-bis(trifluoromethyl)diaminobiphenyl (molar ratio 2:8), and other synthesis conditions such as the molar ratio of diamine to dianhydride, the type and amount of solvent, and the film baking process were the same. A conventional high-temperature imidized RPI-5a film was prepared, with a thickness of 10 ± 2 micrometers, and the main properties are shown in Table 1.

[0113] Comparative Example 5b

[0114] This comparative example is essentially the same as Example 5, except that in Step 3, no end-capping aid was added to the solution, and other synthesis conditions and film preparation processes were the same. The obtained film was designated as RPI-5b, with a thickness of 10 ± 2 micrometers, and the main properties are shown in Table 1.

[0115] Table 1 Main physical properties and performance of polyimide films a

[0116] aThe tensile strength and elongation at break of the film were tested by a universal tensile testing machine; the glass transition temperature was tested by a dynamic mechanical analyzer (DMA); the average light transmittance (400-800 nm) was tested by a UV-Vis spectrophotometer, the yellowness index (YI) was tested by a colorimeter, and the film thickness was 10 ± 2 microns.

[0117] Table 1 lists the mechanical, thermal and optical performance data of the polyimide films prepared in Examples 1-5 and Comparative Examples. Compared with Comparative Examples 1a-5a prepared by conventional high-temperature thermal method, the HPI series films prepared in Examples 1-5 based on the technology of the present application have more excellent comprehensive performance, the tensile strength and elongation at break are greatly improved, and the thermal and optical performance is obviously improved. This shows that the reversible depolymerization and other side reactions of polyamic acid during high-temperature imidization are effectively inhibited, and the catalyst promotes the imidization reaction to be substantially complete at a lower temperature and assists the anhydride end-capping agent, effectively inhibiting the influence of the conventional high-temperature imidization reaction on the material performance, which is particularly beneficial to the improvement of optical transparency at high temperature.

[0118] In Comparative Example 1b, the imidization degree of the polyamic acid in step 2 is less than 20%, and the temperature in the heating and holding stage in step 3 is 300°C. Compared with Example 1, the tensile strength and elongation at break of the prepared RPI-1b film are decreased, and the thermal and optical performance is also affected, indicating that the chemical catalyst needs to be matched with the imidization process conditions after being added, and thus will have an important influence on the material performance.

[0119] In Comparative Examples 2b and 3b, the amount of the chemical catalyst added in step 2 is too much, or the amount of the end group assistant added in step 3 is too much, which leads to a significant decrease in the mechanical and thermal performance of the films RPI-2b and RPI-3b, indicating that the amount of the chemical catalyst and the end group assistant should be kept within a reasonable range.

[0120] Comparative Examples 4b and 5b correspond to step 2 or step 3 without adding any chemical catalyst or any end group assistant, respectively, and also cannot obtain polyimide films with excellent performance, which confirms the effect of the chemical catalyst and the end group assistant on the performance improvement of the film.

[0121] As can be seen from Table 1, the performance parameters of different examples in the present application have certain differences. This is because the reaction system with different structures (i.e., different diamine monomers and dianhydride monomers used) will cause large differences in the performance parameters, and therefore the values of the performance parameters of the examples are not comparable, and the values of the performance parameters of the same reaction system are comparable.

[0122] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A high performance production method of polyimide, characterized by, The method comprises the following steps: Step 1: reacting diamine monomers with dianhydride monomers to obtain a polyamic acid solution; Step 2: adding a chemical catalyst to complete a partial imidization reaction of the polyamic acid solution; Step 3: adding an end group assistant, coating the solution into a film, and heating and keeping warm to complete the imidization reaction; Step 4: high-temperature treatment to obtain high-performance polyimide; In steps 2 and 3, the imidization reaction temperature is below 250°C.

2. The method of claim 1, wherein, In step 2, the reaction temperature is 40-130°C.

3. The method of claim 1, wherein, In step 3, the temperature for heating is 150-250°C.

4. The method according to any one of claims 1 to 3, characterized in that, In step 2, the chemical catalyst is a basic catalyst containing a nitrogen atom.

5. The method of claim 4, wherein, The chemical catalyst is one or more of imidazole, quinoline, pyridine imine type compounds, or piperidine, piperazine, alkyl tertiary amine type compounds.

6. The method of claim 1, wherein, In step 3, the end group assistant is a monofunctional anhydride compound, including one or more of phthalic anhydride, 3-fluorophthalic anhydride, 4-fluorophthalic anhydride, 3,4,5,6-tetrafluorophthalic anhydride, naphthalene anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, maleic anhydride, dimethyl maleic anhydride, acetic anhydride, trifluoroacetic anhydride, propionic anhydride, succinic anhydride.

7. The method of claim 1, wherein, In step 1, the diamine monomers include at least one of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethoxy-4,4'-diaminobiphenyl, 1,4-cyclohexanediamine, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3',5,5'-tetramethylbenzidine, 2,2-bis[3-(3-aminobenzamido)-4-hydroxyphenyl]hexafluoropropane, 2,2-bis[1-(4-aminobenzoyl)-4-aminophenyl]hexafluoropropane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis(trifluoromethyl)-4,4'-diaminophenyl ether, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, 4-aminobenzoic acid-4'-aminophenyl ester, [4-(4-aminobenzoyl)oxyphenyl] 4-aminobenzoate, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)-4,4'-bis(4-aminophenylcarboxamidyl)biphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobenzanilide, 2-(4-aminophenyl)-5-aminobenzoxazole, 2-(4-aminophenyl)-5-aminobenzimidazole, and 9,9-dimethylfluorene-2,7-diamine.

8. The method of claim 7, wherein, In Step 1, the dianhydride monomer includes at least one of 1,2,4,5-benzene-tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 9,9-bis(trifluoromethyl)-2,3,6,7-oxanaphthylene tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, bicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 2,5,7,10-hydrogenated naphthalene tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 4,4-hexafluoroisopropyl phthalic anhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, cyclopentanone bisnorbornanedicarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, N-[4-[4-[(1,3-dioxo-2-benzofuran-5-carbonyl)amino]-2-(trifluoromethyl)phenyl]-3-(trifluoromethyl)phenyl]-1,3-dioxo-2-benzofuran-5-carboxamide, 1,4-phenylene-bisphenyltricarboxylic dianhydride, and 3,3',4,4'-benzophthalic terephthalamide tetracarboxylic dianhydride.

9. The method of claim 1, wherein, In Step 4, the temperature of the high-temperature treatment is 380 to 450°C.

10. Use of the method according to any one of claims 1 to 9 in the field of electrical, electronic, microelectronic, display, communication.

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