Silicon-containing diamine monomer and preparation method thereof, polyimide resin and preparation method thereof, and preparation method of polyimide prepreg

Abstract

The invention discloses a silicon-containing diamine monomer and a preparation method thereof, polyimide resin and a preparation method thereof, and a preparation method of polyimide prepreg, and belongs to the technical field of high polymer materials. The specific scheme is as follows: the structural formula of the silicon-containing diamine monomer is shown in the specification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a silicon-containing diamine monomer and a preparation method thereof, a polyimide resin and a preparation method thereof, and a preparation method of a polyimide prepreg. BACKGROUND

[0002] As a kind of high-performance polymers, polyimide (PI) has excellent thermal stability (thermal decomposition temperature > 500°C), flame retardancy, chemical stability, dielectric properties, and low thermal expansion coefficient, and is widely used in aerospace, electronic packaging, integrated circuits, antenna covers, and other fields.

[0003] At present, polyimide generally has problems of large molecular chain rigidity, high melt viscosity, and poor solubility. Although solution processing or adding processing aids can reduce the processing difficulty of high-viscosity polyimide to some extent, these methods often have high requirements for processing equipment, narrow process window, and may damage the final performance of the material (such as significantly reducing long-term heat resistance, degrading electrical insulation performance at high frequency, or introducing impurities affecting ultra-high purity requirements), and significantly increase production costs (involving solvent recovery and treatment, additional purchase of additives, and more complex process flow control, etc.), thus failing to fundamentally solve the key bottleneck restricting the wide application of polyimide, i.e., the inherent contradiction between excellent comprehensive performance (high thermal stability, high strength and modulus, excellent electrical insulation, etc.) and good processability. PMR type (monomer reactant in-situ polymerization) polyimide resin solves the above problems to some extent, but PMR type polyimide resin still faces problems of low solid content (leading to low processing efficiency and increased risk of product porosity), precipitation at room temperature, poor stability (affecting batch consistency and increasing the complexity of pre-use treatment), etc. On the basis of existing polyimide monomers, optimizing the molecular structure by combining different monomer structures often falls into the dilemma of “performance improvement but processing deterioration, and processing improvement but performance decline”, so it is difficult to balance the inherent contradiction between excellent comprehensive performance and good processability. Therefore, it is urgent to design a new type of polyimide monomer with excellent heat resistance and solubility from the perspective of molecular structure design, and the key is to introduce special structural units that can effectively destroy the close packing of molecular chains, reduce intermolecular forces, while not significantly damaging the backbone rigidity and aromatic ring density to maintain high thermal stability and mechanical strength, laying a molecular foundation for developing a new generation of polyimide materials with excellent comprehensive performance and excellent processability, and fundamentally breaking through the key bottleneck restricting the wide application of polyimide. SUMMARY

[0004] To solve the problems in the background art, the application provides a silicon-containing diamine monomer and a preparation method thereof, a polyimide resin and a preparation method thereof, and a preparation method of a polyimide prepreg.

[0005] To achieve the above object, the application adopts the following technical solutions.

[0006] A silicon-containing diamine monomer has the following structural formula:

[0007]

[0008] The Ar1 structure is one of the following structures:

[0009]

[0010] The Ar2 structure is one of the following structures:

[0011]

[0012] A preparation method of the silicon-containing diamine monomer comprises the following steps:

[0013] I. Nitro compound, iodine, magnesium chips and anhydrous tetrahydrofuran are added to a reaction container and uniformly mixed, and the reaction is carried out at room temperature for 12-24 hours. After the reaction is completed, dichlorosilane is added to the mixture by using a constant-pressure titration funnel, and the reaction is carried out at room temperature for 12-24 hours after the addition is completed. After the reaction is completed, the mixture is filtered, and the solvent is removed by reduced-pressure distillation to obtain a primary product;

[0014] II. The primary product obtained in I is dissolved in a mixed solvent of petroleum ether and ethyl acetate, purified by column chromatography, and the solvent is removed by reduced-pressure distillation. The mixture is dried at 120-150 DEG C under vacuum for 6-12 hours to obtain a silicon-containing dinitro compound;

[0015] III. The silicon-containing dinitro compound obtained in II is dissolved in tetrahydrofuran, and then zinc particles are added. Glacial acetic acid is slowly added to the above solution. After the glacial acetic acid is completely added, the reaction is carried out at 60-80 DEG C under reflux for 1-6 hours. After the reaction is completed, the precipitate is filtered, and potassium hydroxide solution is added dropwise to the filtrate until the pH value of the solution is greater than 10. The mixture is transferred into a separatory funnel, and extracted with dichloromethane for several times, preferably three times. The organic phase is combined, dried with anhydrous magnesium sulfate for 1-2 hours, filtered to remove the anhydrous magnesium sulfate drying agent, and the dichloromethane is removed by reduced-pressure distillation to obtain a silicon-containing diamine crude product;

[0016] IV. The silicon-containing diamine crude product obtained in III is dissolved in a mixed solvent of petroleum ether and ethyl acetate, purified by column chromatography, and the solvent is removed by reduced-pressure distillation. The mixture is dried at 120-150 DEG C under vacuum for 6-12 hours to obtain a silicon-containing diamine.

[0017] ​​In step I, the molar ratio of the nitro compound, magnesium chips, iodine and anhydrous tetrahydrofuran is 1:1.01-1.1:0.02-0.05:2-20, and the molar ratio of dichlorosilane to the nitro compound is 1:2.01~2.05; in step II, the molar ratio of the initial product to the mixed solvent is 1:1~8, and the volume ratio of petroleum ether to ethyl acetate is 1:1~20; in step III, the molar ratio of the silicon-containing dinitro compound, tetrahydrofuran, zinc granules and glacial acetic acid is 1:2~15:1.2~2:1.1~1.5, the concentration of the potassium hydroxide solution is 2~5 mol / L, the molar ratio of the total amount of dichloromethane to the silicon-containing dinitro compound is 2~10:1, and the molar ratio of the amount of anhydrous magnesium sulfate to the silicon-containing dinitro compound is 1:1~2; in step IV, the mass ratio of the crude product of the silicon-containing diamine to the mixed solvent is 1:1~8, and the volume ratio of petroleum ether to ethyl acetate is 1:5~10.

[0018] The nitro compound is one of the following structural formulas:

[0019] wherein X is one of an iodine atom, a bromine atom and a chlorine atom.

[0020] The dichlorosilane is one of 1,3-dichlorotetramethyldisiloxane and 1,4-bis(dimethylchlorosilyl)benzene.

[0021] A polyimide resin containing the silicon-containing diamine monomer or the silicon-containing diamine monomer prepared by the preparation method, and the structural formula of the polyimide resin is

[0022]

[0023] wherein n is a positive integer of 0~50, and Ar3 is one of the following structures:

[0024] .

[0025] A preparation method of the polyimide resin, and the steps are as follows:

[0026] S1, the dianhydride monomer and anhydrous ethanol are added to a three-necked flask, heated and stirred at 75-80℃, and protected by nitrogen, and after the reaction solution is clear and transparent, the reaction is continued for 6h-24h, and the solution A is obtained after cooling to room temperature;

[0027] S2, the silicon-containing diamine monomer is added to the solution A in multiple times under nitrogen protection, and after the addition is completed, the reaction is stirred at room temperature for 8h-24h to obtain the solution B;

[0028] S3, 4-phenyl ethynyl phthalic anhydride and anhydrous ethanol are added into a three-necked flask, heated and stirred at 75-80 DEG C, and protected by nitrogen, until the reaction solution is clear and transparent, then continue to react for 6-18 hours, and cool to room temperature to obtain solution C;

[0029] S4, solution C is added dropwise into solution B under nitrogen protection, after completion of addition, stir at room temperature for 6-24 hours to obtain a silicon-containing polyimide A-stage solution, and heat the silicon-containing polyimide A-stage solution at 200-250 DEG C to remove ethanol to obtain a polyimide resin, wherein the amount of each raw material is calculated according to the stoichiometric ratio according to the value of n in the polyimide resin structural formula in claim 6.

[0030] A preparation method of a polyimide prepreg, comprising the following steps:

[0031] i. The silicon-containing polyimide A-stage solution prepared in step S4 of claim 7 is distilled at 80-120 DEG C under reduced pressure to remove anhydrous ethanol, and a high solid content paste-like polyimide prepolymer is obtained;

[0032] ii. The paste-like polyimide prepolymer is heated at 40-80 DEG C to prepare a polyimide prepolymer adhesive film by a hot melt method;

[0033] iii. The polyimide prepolymer adhesive film is compounded with a reinforcing fiber to prepare a polyimide prepreg.

[0034] The solid content of the high solid content paste-like polyimide prepolymer is 75-90%.

[0035] The reinforcing fiber is one of quartz fiber, carbon fiber, glass fiber and high silicon oxygen fiber.

[0036] Compared with the prior art, the beneficial effects of the present application are:

[0037] 1. By the design concept of "silicon atom bridging non-coplanar aromatic structure", silicon atoms are embedded into the aromatic ring skeleton structure, a series of new silicon-containing diamine systems with "silicon atom bridging coplanar / non-coplanar aromatic structure" are designed and synthesized, the silicon atoms endow the diamine with excellent thermal stability, flexibility and low dielectric properties, breaking through the structural limitations of traditional aromatic diamine, the new series of silicon-containing diamine enriches the polyimide raw material library, significantly enhances the flexibility and diversity of material design, and provides an important monomer basis for developing high-performance and multi-functional polyimide materials.

[0038] 2. By introducing silicon-containing diamine monomers to optimize the molecular structure of polyimide, the solubility and storage stability of the polyimide are effectively improved. As a result, the prepared polyimide A-stage resin (prepolymer) can achieve a solid content of up to 90% in low-toxicity solvents (such as ethanol, isopropanol, etc.), and present a stable paste-like form, and the room temperature storage stability is significantly improved. Specifically, the paste-like polyimide with a solid content of 90% can be stored stably for more than 6 months at room temperature, without delamination, phase separation, etc., greatly improving the material's convenience and process adaptability.

[0039] 3. The key technical bottleneck of polyimide resin difficult to realize hot melt method for preparing prepreg is successfully overcome, and an efficient continuous preparation process is innovatively developed. The process effectively realizes the fine adjustment of the adhesion and lay-up of the prepreg by precisely controlling the thickness uniformity in the film preparation process, and combining the temperature gradient and travel speed control of the film and fiber composite prepreg stage, significantly improving the forming quality and performance consistency of polyimide composite components. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a photo of the T700 carbon fiber / polyimide prepreg prepared in Example 1;

[0041] Figure 2 is a photo of the unidirectional T800 carbon fiber / polyimide prepreg prepared in Example 2;

[0042] Figure 3 is the DMA test result of the unidirectional T800 carbon fiber / polyimide composite material prepared in Example 2;

[0043] Figure 4 is the DMA test result of the quartz fiber cloth / polyimide composite material prepared in Example 3. DETAILED DESCRIPTION

[0044] The technical solutions in the present application will be described below in conjunction with the drawings and examples. Obviously, the described examples are only a part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] Example 1

[0046] Synthesis of silicon-containing diamine monomer:

[0047] (I) Normal temperature, normal pressure, in the atmosphere of argon protection, in the three mouth glass flask with mechanical stirring, add p-bromonitrobenzene (4.0 mol), magnesium (4.2 mol), iodine (0.15 mol) and 20.0 mol of anhydrous tetrahydrofuran, room temperature reaction 24 h, after the reaction is completed, using constant pressure dropping funnel, slowly drop 1,4-bis (dimethylchlorosilane) benzene (1.96 mol) into the reaction vessel at room temperature, after the end of drop, stirring at room temperature for 12 h; filter out the insoluble in the mixed solution, the solution obtained by filtration 150 DEG C under reduced pressure distillation to remove the solvent, obtain the initial product of silicon-containing dinitro compound;

[0048] (II) 3.6 mol of the initial product of silicon-containing dinitro compound prepared by the method of step (I) is dissolved in 2.4 mol of a mixed solvent of petroleum ether and 12.0 mol of ethyl acetate, purified by column chromatography, and the separated solution is distilled under reduced pressure to remove the solvent, dried at 120 DEG C under vacuum for 12 h, and finally the silicon-containing dinitro compound is obtained.

[0049] (III) 3 mol of the silicon-containing dinitro compound prepared by the method of step (II) is dissolved in 15 mol of tetrahydrofuran, then 4 mol of zinc particles are added, and 3.6 mol of glacial acetic acid is slowly added to the above solution. After the addition of glacial acetic acid is completed, reflux reaction is carried out at 75 DEG C for 4 h. After the reaction is completed, the precipitate is filtered, and 4 mol / L potassium hydroxide solution is added dropwise to the filtrate until the pH value of the solution is greater than 10. The mixture is transferred to a separatory funnel, and 5 mol of dichloromethane is used to extract three times each time. The organic phase is combined, dried with 3 mol of anhydrous magnesium sulfate for 2 h, filtered to remove the drying agent, and distilled under reduced pressure to remove dichloromethane to obtain the crude product of silicon-containing diamine.

[0050] (IV) 500 parts of the crude product of silicon-containing diamine prepared by the method of step (III) is dissolved in 1000 parts of a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 1:6, purified by column chromatography, and dried at 120 DEG C under vacuum for 6 h to obtain the silicon-containing diamine monomer.

[0051] Preparation of silicon-containing polyimide resin:

[0052] (S1) Normal temperature, normal pressure, in the atmosphere of nitrogen protection, in the reaction kettle with mechanical stirring, add 3,3',4,4'-benzophenone tetracarboxylic dianhydride (6 mol) and anhydrous ethanol (103.9 mol), heat and stir at 75-80 DEG C, continue to react for 6 h after the reaction solution is clear and transparent, cool to room temperature to obtain solution A;

[0053] (S2) Normal temperature, normal pressure, in the atmosphere of nitrogen protection, 8 mol of the silicon-containing diamine prepared by the above method is added to the solution A obtained in step (S1) in three equal portions, and after the addition is completed, the solution is stirred at room temperature for 12 h to obtain solution B.

[0054] (S3) Normal temperature, normal pressure, in a nitrogen atmosphere, in a three-necked round-bottom flask equipped with mechanical stirring, 4-phenyl acetylene anhydride (4 mol) and anhydrous ethanol (21.6 mol) were added, heated and stirred at 75-80°C until the reaction solution was clear and transparent, then continued to react for 6h, and cooled to room temperature to obtain solution C;

[0055] (S4) Under nitrogen protection, solution C obtained in step (S3) was added dropwise to solution B obtained in step (S2), and after the addition was completed, the reaction was stirred at room temperature for 12h to obtain a low-viscosity silicon-containing polyimide solution;

[0056] Preparation of prepreg:

[0057] The prepreg was prepared by using T700 carbon fiber reinforced silicon-containing polyimide resin. First, the silicon-containing polyimide solution with a solid content of 50 wt% was placed in a reaction kettle, the heating temperature of the reaction kettle was 90°C, and the solvent was removed by reduced pressure distillation to obtain a paste-like polyimide prepolymer with a solid content of 80%. The obtained paste-like polyimide prepolymer was transferred to a roll coating tank, the heating temperature of the tank was 60°C, the gap between the double rollers was adjusted to 0.25mm, and the rotating roller was moved at 2.0m / min to obtain a polyimide prepolymer film.

[0058] The unidirectional T700 carbon fiber was pulled over the polyimide prepolymer film under the action of a tension of 200N, and the polyimide prepolymer film was impregnated into the fiber reinforcement by applying a pressure of 0.05MPa through a pressure roller. The surface release film was pulled over the prepreg under the action of a tension of 150N, and the adhesion between the release film and the prepreg was increased by applying a pressure of 0.05MPa through a pressure roller. The prepreg was wound by a winding device under the action of a tension of 150N to obtain a T700 carbon fiber / polyimide prepreg. The preparation process is shown in Figure 1 .

[0059] Preparation of composite material:

[0060] The above-prepared prepreg was cut into a regular shape by a cutting machine and aligned and laid on a flat mold. The vacuum heat press was vacuumed to below 0.05MPa, heated to 120°C for 30min, 200°C for 1h, 300°C for 1h, 320°C for 45min, pressurized to 10MPa, and continued to be heated at 320°C for 15min. After the heating, the temperature was increased to 380°C and kept for 2h, and then naturally cooled to room temperature to obtain a T700 carbon fiber / polyimide composite material.

[0061] Example 2

[0062] Synthesis of silicon-containing diamine monomer:

[0063] (I) Normal temperature, normal pressure, in the atmosphere of argon protection, in the three mouth glass flask with mechanical stirring, adding 2-bromo-6-nitro pyridine (6.0mol), magnesium (6.06mol), iodine (0.12mol) and 20.0mol anhydrous tetrahydrofuran room temperature reaction 24h, after the reaction is finished, using constant pressure dropping funnel, slowly drop 1,4-bis (dimethyl chloromethyl silyl) benzene (2.95mol) to the reaction container at room temperature, after the drop is finished, stirring at room temperature for 18h; Filter out the insoluble matter in the mixed solution, remove the solvent of the solution obtained by filtration at 140℃ under reduced pressure, obtain the initial product of silicon-containing dinitro compound;

[0064] (II) 4mol initial product of silicon-containing dinitro compound prepared by the synthesis method of step (I) is dissolved in 2.25mol mixed solvent of petroleum ether and 9.75mol ethyl acetate, purified by column chromatography technology, the separated solution is removed by reduced pressure distillation, vacuum dried at 135℃ for 12h, finally obtain the silicon-containing dinitro compound;

[0065] (III) 3mol silicon-containing dinitro compound prepared by the synthesis method of step (II) is dissolved in 15mol tetrahydrofuran, then 4mol zinc particles are added, 3.6mol glacial acetic acid is slowly added to the above solution, after the glacial acetic acid is completely added, reflux at 80℃ for 6h, after the reaction is finished, filter the precipitate, drop 4mol / L potassium hydroxide solution into the filtrate until the pH value of the solution is greater than 10, transfer the mixed solution into a separatory funnel, extract with 5mol dichloromethane three times each time, combine the organic phase, add 3mol anhydrous magnesium sulfate to the organic phase and dry for 1.5h, filter out the drying agent, remove dichloromethane by reduced pressure distillation to obtain the crude product of silicon-containing diamine;

[0066] (IV) 900 parts of crude product of silicon-containing diamine prepared by the synthesis method of step (III) is dissolved in 4500 parts of mixed solvent of petroleum ether and ethyl acetate with a volume ratio of 1:8.5, purified by column chromatography, vacuum dried at 125℃ for 6h, obtain the silicon-containing diamine monomer.

[0067] Preparation of silicon-containing polyimide resin:

[0068] (S1) Normal temperature, normal pressure, in the atmosphere of nitrogen protection, in the three mouth glass flask with mechanical stirring, adding 3,3',4,4'-benzophenone tetracarboxylic dianhydride (4mol) and anhydrous ethanol (68.7mol), heating and stirring at 75-80℃, continue to react for 6h after the reaction solution is clear and transparent, cool to room temperature to obtain solution A;

[0069] (S2) The silicon-containing diamine 5 mol prepared by the above method was evenly divided into 3 parts and added into the solution A obtained in step (S1) under normal temperature, normal pressure and nitrogen protection atmosphere, and after the addition was completed, the solution was stirred at room temperature for 18 h to obtain solution B;

[0070] (S3) 4-phenylethynyl phthalic anhydride (2.0 mol) and anhydrous ethanol (10.8 mol) were added into a three-necked round-bottom flask equipped with mechanical stirring under normal temperature, normal pressure and nitrogen protection atmosphere, and heated and stirred at 75-80°C until the reaction solution was clear and transparent, and then the reaction was continued for 6 h, and the solution C was obtained after cooling to room temperature;

[0071] (S4) The solution C obtained in step (S3) was added dropwise into the solution B obtained in step (S2) under nitrogen protection, and after the addition was completed, the reaction was carried out at room temperature for 12 h to obtain a low-viscosity silicon-containing polyimide solution;

[0072] Preparation of the prepreg:

[0073] The prepreg was prepared by using unidirectional T800 carbon fiber reinforced silicon-containing polyimide resin. First, the silicon-containing polyimide solution with a solid content of 50wt% was placed in a reaction kettle, the heating temperature of the reaction kettle was 120°C, and the solvent was removed by distillation under reduced pressure to obtain a paste-like polyimide prepolymer with a solid content of 82%. The paste-like polyimide prepolymer was transferred to a roll coating tank, the heating temperature of the tank was 60°C, the double-roller gap was adjusted to 0.3mm, and the rotating roller was moved at a speed of 1.5m / min to obtain a polyimide prepolymer film.

[0074] The unidirectional T800 carbon fiber was pulled over the polyimide prepolymer film under the action of a tension of 200N, and the polyimide prepolymer film was impregnated into the fiber reinforcement by applying a pressure of 0.05MPa through a pressure roller. The surface of the prepreg was coated with a surface release film, which was pulled over the prepreg under the action of a tension of 150N, and the adhesion between the release film and the prepreg was increased by applying a pressure of 0.05MPa through a pressure roller. The prepreg was wound by a winding device under the action of a tension of 150N to obtain the prepreg. The photo of the unidirectional T800 carbon fiber / polyimide prepreg is shown in FIG. 1, and the surface of the prepared prepreg is flat and wrinkle-free. Figure 2

[0075] Preparation of the composite material:

[0076] ​The prepared prepreg was cut into a regular shape by a cutting machine, and was aligned and laid on a flat mold. A vacuum bag was prepared by covering the prepreg and the mold with a PI film. The vacuum bag was placed in a hot press tank, and the vacuum inside the vacuum bag was controlled below -95 kPa by a vacuum system. Then, the temperature was increased to 100°C at a rate of 2°C / min, and was kept for 30 min. The temperature was increased to 200°C at a rate of 2°C / min, and was kept for 30 min. The temperature was increased to 300°C at a rate of 2°C / min, and was kept for 1 h. The temperature was increased to 320°C at a rate of 2°C / min, and was kept for 30 min. The pressure was increased to 1.5 MPa at a rate of 20 kPa / min. The temperature was increased to 380°C at a rate of 2°C / min, and was kept for 2 h. Finally, the temperature was decreased to below 50°C at a rate of 2°C / min, and the vacuum bag was taken out. Thus, a T800 carbon fiber / polyimide composite material was obtained. The DMA test results of the T800 carbon fiber / polyimide composite material are shown in FIG. 8. As shown in FIG. 8, the glass transition temperature of the composite material is 452°C. Figure 3

[0077] Example 3

[0078] Synthesis of the silicon-containing diamine monomer:

[0079] (I) In an argon atmosphere, 4-bromonitrobenzene (4.0 mol), magnesium turnings (4.2 mol), iodine (0.1 mol), and 20.0 mol of anhydrous tetrahydrofuran were added to a three-necked round-bottom glass flask equipped with mechanical stirring. The reaction was carried out at room temperature for 24 h. After the reaction was completed, 1,4-bis(dimethylchlorosilyl)benzene (1.96 mol) was slowly added to the reaction vessel at room temperature using a constant-pressure dropping funnel. After the addition was completed, the mixture was stirred at room temperature for 12 h. The insoluble substances in the solution were removed by filtration. The solvent in the filtered solution was removed by distillation under reduced pressure at 150°C. Thus, the initial product of the silicon-containing dinitro compound was obtained.

[0080] (II) The initial product of the silicon-containing dinitro compound (3.6 mol) obtained by the method of step (I) was dissolved in a mixed solvent of 2.4 mol of petroleum ether and 12.0 mol of ethyl acetate. The solution was purified by column chromatography. The solvent in the separated solution was removed by distillation under reduced pressure. The solution was dried under vacuum at 120°C for 12 h. Finally, the silicon-containing dinitro compound was obtained.

[0081] ​(III) The silicon-containing dinitro compound 3.2 mol prepared by the synthesis method of step (II) is dissolved in 18.0 mol of tetrahydrofuran, and then 4.2 mol of zinc particles are added. 4.0 mol of glacial acetic acid is slowly added dropwise to the above solution, and after all the glacial acetic acid is added, the solution is refluxed at 80°C for 6 hours. After the reaction is completed, the precipitate is filtered, and 4 mol / L potassium hydroxide solution is added dropwise to the filtrate until the pH of the solution is greater than 10. The mixture is transferred to a separatory funnel, and each time 4.5 mol of dichloromethane is used to extract three times. The organic phase is combined, dried with 4 mol of anhydrous magnesium sulfate for 1.5 hours, filtered to remove the drying agent, and then dichloromethane is removed by distillation under reduced pressure to obtain a crude silicon-containing diamine product.

[0082] (IV) 800 parts of the crude silicon-containing diamine product obtained in step (III) are dissolved in 1500 parts of a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 1:6.5, and then purified by column chromatography. Vacuum drying is performed at 150°C for 6 hours to obtain a silicon-containing diamine monomer.

[0083] Preparation of a silicon-containing polyimide resin:

[0084] (S1) Under normal temperature and pressure in a nitrogen atmosphere, 3,3,4,4-diphenyl sulfone tetracarboxylic dianhydride (6 mol) and anhydrous ethanol (111.7 mol) are added to a three-necked round-bottom flask equipped with mechanical stirring. Heating and stirring are continued at 75-80°C until the reaction solution becomes clear and transparent, and then the reaction is continued for another 6 hours. The solution A is obtained after cooling to room temperature.

[0085] (S2) Under normal temperature and pressure in a nitrogen atmosphere, the silicon-containing diamine 8 mol synthesized by the above method is added to the solution A obtained in step (S1) in three equal portions. After the addition is completed, stirring is continued at room temperature for 18 hours to obtain solution B.

[0086] (S3) Under normal temperature and pressure in a nitrogen atmosphere, 4-phenyl ethynyl phthalic anhydride (4 mol) and anhydrous ethanol (21.6 mol) are added to a three-necked round-bottom flask equipped with mechanical stirring. Heating and stirring are continued at 75-80°C until the reaction solution becomes clear and transparent, and then the reaction is continued for another 6 hours. The solution C is obtained after cooling to room temperature.

[0087] (S4) The solution C obtained in step (S3) is added dropwise to the solution B obtained in step (S2) under a nitrogen atmosphere. After the addition is completed, stirring is continued at room temperature for 18 hours to obtain a low-viscosity silicon-containing polyimide solution.

[0088] Preparation of a prepreg:

[0089] The prepreg is prepared by using quartz fiber cloth to reinforce a silicon-containing polyimide resin. First, a silicon-containing polyimide solution with a solid content of 50 wt% is placed in a reaction kettle, the reaction kettle is heated to 80°C, and the solvent is removed by reduced pressure distillation to obtain a paste-like polyimide prepolymer with a solid content of 85%. The obtained paste-like polyimide prepolymer is transferred to a roll coating tank, the tank is heated to 60°C, the double-roller gap is adjusted to 0.3 mm, and the rotating roller is moved at a speed of 1.5 m / min to obtain a polyimide prepolymer film.

[0090] The quartz fiber cloth is pulled over the polyimide prepolymer film under the action of a tension of 220 N, and the polyimide prepolymer film is impregnated into the fiber reinforcement by applying a pressure of 0.1 MPa through a pressure roller. The surface of the prepreg is covered with a film, the surface release film is pulled over the prepreg under the action of a tension of 150 N, and the degree of adhesion between the release film and the prepreg is increased by applying a pressure of 0.1 MPa through a pressure roller. The prepreg is wound using a winding device under the action of a tension of 180 N to obtain a quartz fiber cloth / polyimide prepreg.

[0091] Composite material preparation:

[0092] The prepreg prepared above is cut into a regular shape using a cutting machine and is aligned and laid on a flat mold. A PI film is used to cover the prepreg and the mold to prepare a vacuum bag. The vacuum bag is placed in a hot press tank, and a vacuum system is used to control the internal vacuum of the vacuum bag to be below -90 kPa. Then, the temperature is increased to 100°C at a rate of 2°C / min, maintained for 30 min, increased to 200°C at a rate of 2°C / min, maintained for 30 min, increased to 300°C at a rate of 2°C / min, maintained for 1 h, increased to 320°C at a rate of 2°C / min, maintained for 30 min, pressurized to 1.5 MPa at a rate of 20 kPa / min, increased to 380°C at a rate of 2°C / min, maintained for 2 h, and finally cooled to below 50°C at a rate of 2°C / min. The vacuum bag is taken out, and a quartz fiber cloth / polyimide composite material is obtained. The DMA test results of the performance of the quartz fiber cloth / polyimide composite material are shown in the accompanying Figure 4 The glass transition temperature of the composite material appears before 500°C, and the glass transition temperature is greater than 500°C. The performance of the quartz fiber cloth / polyimide composite material is shown in the following table.

[0093] Performance of quartz fiber cloth / polyimide composite material

[0094]

[0095] Example 4

[0096] Synthesis of silicon-containing diamine monomer:

[0097] (I) Normal temperature, normal pressure, in the reaction kettle equipped with mechanical stirring, adding 3-bromo-5-nitrotoluene (7.0 mol), magnesium chips (7.14 mol), iodine (0.2 mol) and 100 mol of tetrahydrofuran in argon atmosphere, reacting for 24 h at room temperature, after the reaction, using constant pressure dropping funnel, slowly adding 1,4-bis(dimethylchlorosilyl) benzene (3.41 mol) to the reaction vessel at room temperature, after the dropping is completed, stirring for 12 h at room temperature; removing the insoluble substances in the mixed solution by filtration, removing the solvent from the solution obtained by filtration by vacuum distillation, obtaining the initial product of silicon-containing dinitro compound;

[0098] (II) Dissolving 3.2 mol of the initial product of silicon-containing dinitro compound obtained by the method of step (I) in a mixed solvent of 3.0 mol of petroleum ether and 15.0 mol of ethyl acetate, purifying by column chromatography, removing the solvent from the separated solution by vacuum distillation, vacuum drying at 120℃ for 12 h, finally obtaining the silicon-containing dinitro compound.

[0099] (III) Dissolving 3 mol of the silicon-containing nitro compound obtained by the method of step (II) in 15 mol of tetrahydrofuran, then adding 4.2 mol of zinc particles, slowly adding 3.9 mol of glacial acetic acid to the above solution, after the addition of glacial acetic acid is completed, refluxing at 70℃ for 8 h, after the reaction is completed, filtering the precipitate, adding 2.5 mol / L of potassium hydroxide solution to the filtrate until the pH value of the solution is greater than 10, transferring the mixed solution into a separatory funnel, extracting three times with 6 mol of dichloromethane respectively, drying the organic phase with 5 mol of anhydrous magnesium sulfate for 1 h, removing the drying agent by filtration, removing dichloromethane by vacuum distillation, obtaining the crude product of silicon-containing diamine.

[0100] (IV) Dissolving 1200 parts of the crude product of silicon-containing diamine obtained in III in 2000 parts of a mixed solvent of petroleum ether and ethyl acetate with a volume ratio of 1:7.5, purifying by column chromatography, vacuum drying at 120℃ for 12 h, obtaining the silicon-containing diamine monomer.

[0101] Preparation of silicon-containing polyimide resin:

[0102] (S1) In a three-necked round-bottom flask equipped with mechanical stirring, adding 4,4'-biphenyl ether dianhydride (4 mol) and anhydrous ethanol (72.98 mol) in nitrogen atmosphere, heating and stirring at 75-80℃, after the reaction solution becomes clear and transparent, continuing to react for 6 h, cooling to room temperature to obtain solution A;

[0103] (S2) In nitrogen atmosphere, adding 6 mol of the silicon-containing diamine obtained by the above method to solution A obtained in step (S1) in three equal portions, after the addition is completed, stirring at room temperature and continuing to react for 12 h, obtaining solution B;

[0104] (S3) Normal temperature, normal pressure, in the nitrogen protection atmosphere, in the three mouth round bottom flask which is equipped with the mechanical stirring adds 4-phenyl acetylene group phthalic anhydride (4mol) and anhydrous ethanol (21.6mol), 75-80℃ heating stirring, until the reaction solution is clear and transparent, then continue to react for 6h, cool to room temperature to obtain solution C;

[0105] (S4) Under nitrogen protection, solution C obtained in step (S3) is added dropwise to solution B obtained in step (S2), after the addition is completed, the reaction is stirred at room temperature for 12h to obtain a low viscosity silicon-containing polyimide solution;

[0106] Preparation of prepreg:

[0107] The prepreg is prepared by using T800 carbon fiber reinforced silicon-containing polyimide resin. First, the silicon-containing polyimide solution with a solid content of 50wt% is placed in a reaction kettle, the heating temperature of the reaction kettle is 80℃, and the solvent is removed by reduced pressure distillation to obtain a paste-like polyimide prepolymer with a solid content of 85%. The obtained paste-like polyimide prepolymer is transferred to a roll coating tank, the heating temperature of the tank is 70℃, the gap between the two rollers is adjusted to 0.33mm, and the rotating roller is moved at a speed of 1.8m / min to obtain a polyimide prepolymer film.

[0108] The unidirectional T800 carbon fiber is pulled over the polyimide prepolymer film under the action of a tension of 180N, and the polyimide prepolymer film is impregnated into the fiber reinforcement by applying a pressure of 0.06MPa through a pressure roller. The surface release film is pulled over the prepreg under the action of a tension of 180N, and the degree of adhesion between the release film and the prepreg is increased by applying a pressure of 0.08MPa through a pressure roller. The prepreg is wound using a winding device under a tension of 150N to obtain a prepreg with a smooth surface without wrinkles.

[0109] Preparation of composite material:

[0110] The above prepared prepreg is cut into a regular shape using a cutting machine and aligned and laid on a flat mold. A PI film is used to cover the prepreg and the mold to prepare a vacuum bag. The vacuum bag is placed in a hot press tank, and the vacuum inside the vacuum bag is controlled to be below -95kPa using a vacuum system. Then, the temperature is increased to 100℃ at a rate of 2℃ / min and held for 30min, increased to 200℃ at a rate of 2℃ / min and held for 30min, increased to 300℃ at a rate of 2℃ / min and held for 1h, increased to 320℃ at a rate of 2℃ / min and held for 30min, pressurized to 1.5MPa at a rate of 20kPa / min, increased to 380℃ at a rate of 2℃ / min and held for 2h, and finally cooled to below 50℃ at a rate of 2℃ / min. The vacuum bag is taken out, and a T800 carbon fiber / polyimide composite material is obtained. The properties of the T800 carbon fiber / polyimide composite material are shown in the following table.

[0111] Properties of t800 carbon fiber / polyimide composites

[0112]

[0113] Furthermore, it should be understood that although the description is made according to the embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and the skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by the skilled in the art.

Claims

1. A silicon diamine monomer, characterized in that: The structural formula of the silanediamine monomer is shown in the figure below: The Ar1 structure is one of the following structures: ； The Ar2 structure is one of the following structures: 。 2. A method for preparing the silanediamine monomer according to claim 1, characterized in that: Includes the following steps: I. Mix the nitro compound, elemental iodine, magnesium shavings, and anhydrous tetrahydrofuran thoroughly and react at room temperature for 12-24 hours. After the reaction is complete, add dichlorosilane dropwise to the mixture using a constant pressure titration funnel. After the addition is complete, react at room temperature for 12-24 hours. After the reaction is complete, filter the mixture and remove the solvent by vacuum distillation to obtain the initial product. II. The primary product obtained in I was dissolved in a mixed solvent of petroleum ether and ethyl acetate, purified by column chromatography, the solvent was removed by vacuum distillation, and the product was dried under vacuum at 120℃~150℃ to obtain a silicon-containing dinitro compound. III. Dissolve the silicon-containing dinitro compound obtained in II in tetrahydrofuran, then add zinc granules, and slowly add glacial acetic acid dropwise to the above solution. After all the glacial acetic acid has been added, reflux at 60-80°C for 1-6 hours. After the reaction is complete, filter the precipitate, add potassium hydroxide solution dropwise to the filtrate until the pH of the solution is greater than 10, transfer the mixture to a separatory funnel, extract several times with dichloromethane, combine the organic phases, dry the organic phase with anhydrous magnesium sulfate, filter to remove the anhydrous magnesium sulfate drying agent, and remove dichloromethane by vacuum distillation to obtain the crude product containing silicon diamine. IV. The crude silanediamine obtained in III was dissolved in a mixed solvent of petroleum ether and ethyl acetate, purified by column chromatography, the solvent was removed by vacuum distillation, and the product was dried under vacuum at 120℃~150℃ to obtain the silanediamine.

3. The preparation method according to claim 2, characterized in that: In step I, the molar ratio of the nitro compound, magnesium shavings, elemental iodine, and anhydrous tetrahydrofuran is 1:1.01-1.1:0.02-0.05:2-20, and the molar ratio of the added dichlorosilane to the nitro compound is 1:2.01-2.05; in step II, the molar ratio of the initial product to the mixed solvent is 1:1-8, and the volume ratio of petroleum ether to ethyl acetate is 1:1-20; in step III, the silicon-containing dinitro compound, tetrahydrofuran, zinc granules, and... The molar ratio of glacial acetic acid is 1:2~15:1.2~2:1.1~1.5, the concentration of the potassium hydroxide solution is 2~5 mol / L, the molar ratio of the total amount of dichloromethane to the silicon-containing dinitro compound is 2~10:1, and the molar ratio of the amount of anhydrous magnesium sulfate to the silicon-containing dinitro compound is 1:1~2; in step IV, the mass ratio of the crude silicon-containing diamine product to the mixed solvent is 1:1~8, and the volume ratio of petroleum ether to ethyl acetate is 1:5~10.

4. The preparation method according to claim 2, characterized in that: The nitro compound is one of the following structural formulas: Where X is one of the iodine, bromine, and chlorine atoms.

5. The preparation method according to claim 2, characterized in that: The dichlorosilane is one of 1,3-dichlorotetramethyldisiloxane and 1,4-bis(dimethylchlorosilyl)benzene.

6. A polyimide resin containing the silicon-containing diamine monomer of claim 1 or the silicon-containing diamine monomer prepared by the preparation method of any one of claims 2-5, characterized in that: The structural formula of the polyimide resin is as follows: Where n is a positive integer from 0 to 50, and the Ar3 structure is one of the following structures: 。 7. A method for preparing the polyimide resin according to claim 6, characterized in that, The steps are as follows: S1. Mix the dianhydride monomer with anhydrous ethanol, heat and stir at 75-80℃, and purge with nitrogen for protection until the reaction solution is clear and transparent. Continue the reaction for 6-24 hours, and then cool to room temperature to obtain solution A. S2. Under nitrogen protection, the silanediamine monomer was added to solution A in multiple portions. After the addition was complete, the mixture was stirred at room temperature for 8-24 hours to obtain solution B. S3. Mix 4-phenylethynyl phthalic anhydride with anhydrous ethanol, heat and stir at 75-80℃, and purge with nitrogen for protection until the reaction solution is clear and transparent. Continue the reaction for 6-18 hours, and then cool to room temperature to obtain solution C. S4. Under nitrogen protection, solution C is added dropwise to solution B. After the addition is complete, the mixture is stirred at room temperature for 6-24 hours to obtain a silicon-containing polyimide A-stage solution. The silicon-containing polyimide A-stage solution is heated at 200-250°C to remove ethanol and obtain polyimide resin. The amount of each raw material is calculated according to the stoichiometric ratio of n in the polyimide resin structural formula according to claim 6.

8. A method for preparing a polyimide prepreg, characterized in that, Includes the following steps: i. The silicon-containing polyimide A-stage solution prepared in step S4 of claim 7 is subjected to vacuum distillation at 80~120℃ to remove anhydrous ethanol, thereby obtaining a high-solids-content paste-like polyimide prepolymer. ii. Heat the paste-like polyimide prepolymer at 40~80℃ to prepare a polyimide prepolymer film by hot melt method; iii. Polyimide prepreg is prepared by combining polyimide prepolymer film with reinforcing fibers.

9. The preparation method according to claim 8, characterized in that: The high-solids-content paste-like polyimide prepolymer has a solids content of 75-90%.

10. The preparation method according to claim 8, characterized in that: The reinforcing fiber is one of quartz fiber, carbon fiber, glass fiber, and high-silica fiber.

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