Preparation method of polyimide graphitized film

Abstract

The present invention relates to the technical field of graphitized films, and discloses a preparation method of a polyimide graphitized film. In the present invention, a diamine monomer, a dianhydride monomer, intermediate 2, and amino-functionalized multi-walled carbon nanotubes are reacted to obtain a polyimide precursor film; then high-temperature heat treatment is carried out to obtain a polyimide graphitized film. The multi-walled carbon nanotube structure in the polyimide graphitized film of the present invention is graft-modified, introducing a large number of benzene rings and amino groups. Adding it to the polyimide graphitized film improves its electrical conductivity and thermal conductivity; the bromine in intermediate 1 reacts with the boric acid group in 4-aminophenylboronic acid, improving the substitution degree of its benzene ring and amino group, and forming a larger plane with the benzene ring in the amino-functionalized multi-walled carbon nanotubes, while more effectively transferring heat; the amino groups in the amino-functionalized multi-walled carbon nanotubes and intermediate 2 constitute a large amount of nitrogen sources, doping graphene and high-temperature treatment, improving the electrical conductivity of the polyimide graphitized film.

Description

Technical Field

[0001] The present invention relates to the technical field of graphitized films, and specifically to a preparation method of a polyimide graphitized film. Background Art

[0002] Polyimide has many excellent properties and is widely used in the fields of electronics, aviation, communication, etc. The traditional graphite film prepared from polyimide has limitations in industrial applications due to its low graphitization rate, large fluctuations in mechanical properties, and unsatisfactory thermal conductivity. For example, Patent CN118439878A discloses a high-thermal-conductivity polyimide composite graphite film and its preparation method. The polyimide composite graphite film obtained by this invention has a high degree of graphitization and excellent transverse and longitudinal thermal conductivity, but its electrical conductivity has not been improved. Summary of the Invention

[0003] (I) Technical Problems to be Solved

[0004] In view of the deficiencies of the prior art, the present invention provides a preparation method of a polyimide graphitized film, which has good thermal and electrical conductivity effects.

[0005] (II) Technical Solutions

[0006] To achieve the above object, the present invention provides the following technical solutions: A preparation method of a polyimide graphitized film, the preparation method of the polyimide graphitized film includes the following steps:

[0007] (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene to a reactor filled with acetone solvent, stir and dissolve, then continue to add potassium carbonate thereto, reflux and react at 40 - 60 °C for 8 - 10 h. After completion, cool to room temperature, filter, wash with distilled water, and dry to obtain Intermediate 1;

[0008] (2) Add Intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, protect with nitrogen, continue to add triphenylphosphine palladium catalyst thereto, heat up to 55 - 70 °C and react for 4 - 6 h. After the reaction, distill, filter by suction, and dry to obtain Intermediate 2;

[0009] (3) Add 15 - 30 parts by weight of 2 - methyl - p - phenylenediamine and 20 - 35 parts by weight of biphenyl dianhydride to N,N - dimethylformamide solvent, stir and mix. Then add 2 - 6 parts by weight of intermediate 2 and 3 - 7 parts by weight of amino - functionalized multi - walled carbon nanotubes to obtain solution A with a mass fraction of 20 - 25%. Then coat solution A on glass, and the solution A layer on the glass is dried in a curing oven at 60 - 75 °C for 1 - 1.5 h. Then use a high - temperature oven to increase the temperature in stages, heat at 150 - 155 °C for 1 - 1.2 h, heat at 200 - 210 °C for 1 - 1.5 h, heat at 250 - 260 °C for 1 - 1.2 h, and heat at 350 - 360 °C for 1 - 1.5 h to obtain a polyimide precursor film;

[0010] (4) Clamp the polyimide precursor film between graphite plates, use an ultra - high - temperature furnace with a graphite heater, and under reduced pressure, heat it to 1000 °C at a rate of 16 - 17 °C / min for pretreatment. Then, use the ultra - high - temperature furnace, in an argon environment atmosphere with a pressure of 0.08 MPa, heat it to 2700 °C at a heating rate of 7 - 8 °C / min. Then, in an argon environment atmosphere with a pressure of 0.08 MPa, heat it to the maximum temperature of 2800 °C at a rate of 2 - 3 °C / min, and keep it at this maximum temperature for 1 - 1.5 h, and then cool it to obtain a graphitized polyimide film.

[0011] Preferably, in the step (1), the mass ratio of 3,3'-dibromo - 4,4'-biphenol, 1,2,4,5 - tetrabromobenzene, and potassium carbonate is 1:1.2 - 1.6:0.2 - 0.3.

[0012] Preferably, in the step (2), the mass ratio of intermediate 1, 4 - aminophenylboronic acid, and triphenylphosphine palladium catalyst is 0.7 - 0.9:1:0.01 - 0.02.

[0013] Preferably, the preparation method of the amino - functionalized multi - walled carbon nanotubes in the step (3) is as follows: Add multi - walled carbon nanotubes and p - nitrobenzoic acid to polyphosphoric acid, stir magnetically until evenly dispersed, continue to stir mechanically at 115 - 125 °C for 1 - 2 h, then cool the temperature to 40 - 55 °C and add stannous chloride to react for 2 - 4 h. After completion, cool to room temperature, wash with deionized water, and dry under vacuum to obtain amino - functionalized multi - walled carbon nanotubes.

[0014] Preferably, the mass ratio of the multi - walled carbon nanotubes, p - nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:8 - 10:55 - 60:30 - 35.

[0015] (III) Beneficial technical effects

[0016] In the present invention, substitution reactions are carried out on the phenolic hydroxyl groups in 3,3'-dibromo-4,4'-biphenol and the bromine in 1,2,4,5-tetrabromobenzene to introduce a large number of bromine groups, thereby obtaining intermediate 1. The bromine in intermediate 1 reacts with the boric acid group in 4-aminophenylboronic acid to introduce a large number of benzene ring structures and amino groups, thereby obtaining intermediate 2. Esterification reactions are carried out on the hydroxyl groups in multi-walled carbon nanotubes and the carboxyl groups in p-nitrobenzoic acid to introduce nitro groups, and then stannous chloride is added for reaction to generate amino groups, thereby obtaining amino-functionalized multi-walled carbon nanotubes. The diamine monomer, dianhydride monomer, intermediate 2, and amino-functionalized multi-walled carbon nanotubes are reacted to obtain a polyimide precursor film. Then, high-temperature heat treatment is carried out to obtain a polyimide graphitized film.

[0017] In the polyimide graphitized film of the present invention, the multi-walled carbon nanotube structure is graft-modified, introducing a large number of benzene rings and amino groups, and at the same time reducing the aggregation of multi-walled carbon nanotubes. Adding it to the polyimide graphitized film improves its electrical conductivity and heat conduction effect. The reaction between the bromine in intermediate 1 and the boric acid group in 4-aminophenylboronic acid improves the substitution degree of its benzene ring and amino group, and forms a larger plane with the benzene ring in the amino-functionalized multi-walled carbon nanotubes. The skeleton structure is relatively flat, improving the mechanical properties of the polyimide graphitized film and transferring heat more effectively at the same time. The amino groups in the amino-functionalized multi-walled carbon nanotubes and intermediate 2 constitute a large amount of nitrogen sources. Doping graphene and high-temperature treatment improve the electrical conductivity of the polyimide graphitized film. Detailed implementation mode Example 1

[0018] (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene to a reactor containing acetone solvent, stir and dissolve, and then continue to add potassium carbonate to it. The mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene, and potassium carbonate is 1:1.2:0.2. Carry out reflux reaction at 40 °C for 8 h. After completion, cool to room temperature, filter, wash with distilled water, and dry to obtain intermediate 1;

[0019] (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, protect with nitrogen, and continue to add triphenylphosphine palladium catalyst to it. The mass ratio of intermediate 1, 4-aminophenylboronic acid, and triphenylphosphine palladium catalyst is 0.7:1:0.01. Heat up to 55 °C and react for 4 h. After the reaction, distill, filter by suction, and dry to obtain intermediate 2;

[0020] (3) Add multi-walled carbon nanotubes and p-nitrobenzoic acid into polyphosphoric acid, stir magnetically until evenly dispersed, continue to stir mechanically at 115 °C for 1 h, then cool the temperature to 40 °C and add stannous chloride thereto for reaction for 2 h. The mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:8:55:30. After completion, cool to room temperature, wash with deionized water, and dry in vacuum to obtain amino-functionalized multi-walled carbon nanotubes;

[0021] (4) Add 15 parts by weight of 2-methyl-p-phenylenediamine and 20 parts by weight of biphenyl dianhydride into N,N-dimethylformamide solvent, stir and mix, add 2 parts by weight of intermediate 2 and 3 parts by weight of amino-functionalized multi-walled carbon nanotubes thereto to obtain solution A with a mass fraction of 20%. Then coat solution A on glass, and dry the solution A layer on the glass in a curing oven at 60 °C for 1 h, and then use a high-temperature oven to raise the temperature in stages, heat at 150 °C for 1 h, heat at 200 °C for 1 h, heat at 250 °C for 1 h, and heat at 350 °C for 1 h to obtain a polyimide precursor film;

[0022] (5) Clamp the polyimide precursor film between graphite plates, use an ultra-high temperature furnace with a graphite heater, heat up to 1000 °C at a rate of 16 °C / min under reduced pressure for pretreatment. Then, use the ultra-high temperature furnace, heat up to 2700 °C at a heating rate of 7 °C / min in an argon atmosphere under a pressure of 0.08 MPa, and then heat up to the maximum temperature of 2800 °C at a rate of 2 °C / min in an argon atmosphere under a pressure of 0.08 MPa, hold at this maximum temperature for 1 h, and then cool to obtain a graphitized polyimide film. Example 2

[0023] (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene into a reactor equipped with acetone solvent, stir to dissolve, and then continue to add potassium carbonate thereto. The mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene, and potassium carbonate is 1:1.6:0.3. React under reflux at 60 °C for 10 h. After completion, cool to room temperature, filter, wash with distilled water, and dry to obtain intermediate 1;

[0024] (2) Add intermediate 1 and 4-aminophenylboronic acid into 1,4-dioxane solvent, introduce nitrogen for protection, and continue to add triphenylphosphine palladium catalyst thereto. The mass ratio of intermediate 1, 4-aminophenylboronic acid, and triphenylphosphine palladium catalyst is 0.9:1:0.02. Heat up to 70 °C and react for 6 h. After the reaction, distill, filter by suction, and dry to obtain intermediate 2;

[0025] (3) Add multi-walled carbon nanotubes and p-nitrobenzoic acid into polyphosphoric acid, stir magnetically until evenly dispersed, continue to stir mechanically at 125 °C for 2 h, then cool the temperature to 55 °C and add stannous chloride thereto and react for 4 h. The mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:10:60:35. After completion, cool to room temperature, wash with deionized water, and dry in vacuum to obtain amino-functionalized multi-walled carbon nanotubes;

[0026] (4) Add 30 parts by weight of 2-methyl-p-phenylenediamine and 35 parts by weight of biphenyl dianhydride into N,N-dimethylformamide solvent, stir and mix, add 6 parts by weight of intermediate 2 and 7 parts by weight of amino-functionalized multi-walled carbon nanotubes thereto to obtain solution A with a mass fraction of 25%. Then coat solution A on glass, and dry the solution A layer on the glass in a curing oven at 75 °C for 1.5 h. Then use a high-temperature oven to raise the temperature in stages, heat at 155 °C for 1.2 h, heat at 210 °C for 1.5 h, heat at 260 °C for 1.2 h, and heat at 360 °C for 1.5 h to obtain a polyimide precursor film;

[0027] (5) Sandwich the polyimide precursor film between graphite plates, use an ultra-high temperature furnace with a graphite heater, heat up to 1000 °C at a rate of 17 °C / min under reduced pressure for pretreatment. Then, use the ultra-high temperature furnace, under an argon atmosphere with a pressure of 0.08 MPa, heat up to 2700 °C at a heating rate of 8 °C / min, and then under an argon atmosphere with a pressure of 0.08 MPa, heat up to the maximum temperature of 2800 °C at a rate of 3 °C / min, hold at this maximum temperature for 1.5 h, and then cool to obtain a graphitized polyimide film. Example 3

[0028] (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene into a reactor containing acetone solvent, stir to dissolve, and then continue to add potassium carbonate thereto. The mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene, and potassium carbonate is 1:1.4:0.25. React under reflux at 50 °C for 9 h. After completion, cool to room temperature, filter, wash with distilled water, and dry to obtain intermediate 1;

[0029] (2) Add intermediate 1 and 4-aminophenylboronic acid into 1,4-dioxane solvent, introduce nitrogen for protection, and continue to add triphenylphosphine palladium catalyst thereto. The mass ratio of intermediate 1, 4-aminophenylboronic acid, and triphenylphosphine palladium catalyst is 0.5:1:0.015. Raise the temperature to 62 °C and react for 5 h. After the reaction, distill, filter by suction, and dry to obtain intermediate 2;

[0030] (3) Add multi-walled carbon nanotubes and p-nitrobenzoic acid to polyphosphoric acid, stir magnetically until evenly dispersed, continue to stir mechanically at 120 °C for 1.5 h, then cool the temperature to 50 °C and add stannous chloride thereto for reaction for 3 h. The mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:9:57.5:32.5. After completion, cool to room temperature, wash with deionized water, and dry in vacuum to obtain amino-functionalized multi-walled carbon nanotubes;

[0031] (4) Add 22.5 parts by weight of 2-methyl-p-phenylenediamine and 27.5 parts by weight of biphenyl dianhydride to N,N-dimethylformamide solvent, stir and mix, add 4 parts by weight of intermediate 2 and 5 parts by weight of amino-functionalized multi-walled carbon nanotubes thereto to obtain solution A with a mass fraction of 22.5%. Then coat solution A on glass, and dry the solution A layer on the glass in a curing oven at 67 °C for 1.25 h, and then use a high-temperature oven to raise the temperature in stages, heat at 153 °C for 1.1 h, 205 °C for 1.2 h, 255 °C for 1.1 h, and 355 °C for 1.3 h to obtain a polyimide precursor film;

[0032] (5) Sandwich the polyimide precursor film between graphite plates, use an ultra-high temperature furnace with a graphite heater, heat up to 1000 °C at a rate of 16.5 °C / min under reduced pressure for pretreatment. Then, use the ultra-high temperature furnace, under a pressurized argon atmosphere of 0.08 MPa, heat up to 2700 °C at a heating rate of 7.5 °C / min, and then under a pressurized argon atmosphere of 0.08 MPa, heat up to the maximum temperature of 2800 °C at a rate of 2.5 °C / min, hold at this maximum temperature for 1.3 h, and then cool to obtain a graphitized polyimide film.

[0033] Comparative Example 1

[0034] (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene to a reactor containing acetone solvent, stir to dissolve, and then continue to add potassium carbonate thereto. The mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene, and potassium carbonate is 1:1.4:0.25. React under reflux at 50 °C for 9 h. After completion, cool to room temperature, filter, wash with distilled water, and dry to obtain intermediate 1;

[0035] (2) Add intermediate 1 and 4-aminophenylboronic acid to 1,4-dioxane solvent, protect with nitrogen, and continue to add triphenylphosphine palladium catalyst thereto. The mass ratio of intermediate 1, 4-aminophenylboronic acid, and triphenylphosphine palladium catalyst is 0.5:1:0.015. Raise the temperature to 62 °C and react for 5 h. After the reaction, distill, filter with suction, and dry to obtain intermediate 2;

[0036] (3) Add 22.5 parts by weight of 2-methyl-p-phenylenediamine and 27.5 parts by weight of biphenyl dianhydride to N,N-dimethylformamide solvent, stir and mix them. Then add 4 parts by weight of intermediate 2 to obtain solution A with a mass fraction of 22.5%. Then coat solution A on glass, and the solution A layer on the glass is dried in a curing oven at 67 °C for 1.25 h. Then use a high-temperature oven to increase the temperature in stages, heat at 153 °C for 1.1 h, at 205 °C for 1.2 h, at 255 °C for 1.1 h, and at 355 °C for 1.3 h to obtain a polyimide precursor film;

[0037] (4) Clamp the polyimide precursor film between graphite plates, use an ultra-high temperature furnace with a graphite heater, and under reduced pressure, heat it to 1000 °C at a rate of 16.5 °C / min for pretreatment. Then, use the ultra-high temperature furnace, in an argon environment atmosphere with a pressure of 0.08 MPa, heat it to 2700 °C at a heating rate of 7.5 °C / min. Then, still in an argon environment atmosphere with a pressure of 0.08 MPa, heat it to the highest temperature of 2800 °C at a rate of 2.5 °C / min, and hold it at this highest temperature for 1.3 h. Then cool it to obtain a polyimide graphitized film.

[0038] Comparative Example 2

[0039] (1) Add multi-walled carbon nanotubes and p-nitrobenzoic acid to polyphosphoric acid, stir magnetically until evenly dispersed, continue to stir mechanically at 120 °C for 1.5 h, then cool the temperature to 50 °C and add stannous chloride to react for 3 h. The mass ratio of multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:9:57.5:32.5. After completion, cool to room temperature, wash with deionized water, and dry in vacuum to obtain amino-functionalized multi-walled carbon nanotubes;

[0040] (2) Add 22.5 parts by weight of 2-methyl-p-phenylenediamine and 27.5 parts by weight of biphenyl dianhydride to N,N-dimethylformamide solvent, stir and mix them. Then add 5 parts by weight of amino-functionalized multi-walled carbon nanotubes to obtain solution A with a mass fraction of 22.5%. Then coat solution A on glass, and the solution A layer on the glass is dried in a curing oven at 67 °C for 1.25 h. Then use a high-temperature oven to increase the temperature in stages, heat at 153 °C for 1.1 h, at 205 °C for 1.2 h, at 255 °C for 1.1 h, and at 355 °C for 1.3 h to obtain a polyimide precursor film;

[0041] (3) The polyimide precursor film is clamped on a graphite plate, and the temperature is raised to 1000°C at a rate of 16.5°C / min under reduced pressure in an ultra-high temperature furnace with a graphite heater for pretreatment. Next, the temperature is raised to 2700°C at a rate of 7.5°C / min in an ultra-high temperature furnace in a pressurized argon environment of 0.08 MPa, and then the temperature is raised to a maximum temperature of 2800°C at a rate of 2.5°C / min in a pressurized argon environment of 0.08 MPa. The temperature is maintained at the maximum temperature for 1.3 h, and then cooled to obtain a polyimide graphitized film.

[0042] Performance Testing

[0043] The electrical conductivity of the polyimide graphitized film was tested, and the thermal conductivity was tested according to the ASTM E1461-13 standard.

[0044] Table 1: Electrical conductivity and thermal conductivity test.

[0045]

[0046] It can be seen from Table 1 that Examples 1-3 of the present invention have better electrical and thermal conductivity effects than Comparative Examples 1-2.

[0047] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preparation method of a polyimide graphitized film, characterized in that, The preparation method of the polyimide graphitized film comprises the following steps: (1) Add 3,3'-dibromo-4,4'-biphenol and 1,2,4,5-tetrabromobenzene into a reactor filled with acetone solvent, stir to dissolve, then continue to add potassium carbonate thereto, reflux and react at 40 - 60 °C for 8 - 10 h. After completion, cool to room temperature, filter, wash with distilled water, and dry to obtain intermediate 1; (2) Add intermediate 1 and 4-aminophenylboronic acid into 1,4-dioxane solvent, protect with nitrogen, continue to add triphenylphosphine palladium catalyst thereto, heat up to 55 - 70 °C and react for 4 - 6 h. After the reaction, distill, filter by suction, and dry to obtain intermediate 2; (3) Add 15 - 30 parts by weight of 2-methyl-p-phenylenediamine and 20 - 35 parts by weight of biphenyl dianhydride into N,N-dimethylformamide solvent, stir and mix, add 2 - 6 parts by weight of intermediate 2 and 3 - 7 parts by weight of amino-functionalized multi-walled carbon nanotubes thereto to obtain solution A. Then coat solution A on glass, and dry the solution A layer on the glass in a curing box at 60 - 75 °C for 1 - 1.5 h, then use a high-temperature oven to raise the temperature in stages, heat at 150 - 155 °C for 1 - 1.2 h, 200 - 210 °C for 1 - 1.5 h, 250 - 260 °C for 1 - 1.2 h, and 350 - 360 °C for 1 - 1.5 h to obtain a polyimide precursor film; (4) Clamp the polyimide precursor film between graphite plates, use an ultra-high temperature furnace with a graphite heater, heat up to 1000 °C at a rate of 16 - 17 °C / min under reduced pressure for pretreatment. Then, use the ultra-high temperature furnace, under an argon atmosphere with a pressure of 0.08 MPa, heat up to 2700 °C at a heating rate of 7 - 8 °C / min, and then under an argon atmosphere with a pressure of 0.08 MPa, heat up to the highest temperature of 2800 °C at a rate of 2 - 3 °C / min, and maintain at this highest temperature for 1 - 1.5 h, then cool to obtain a polyimide graphitized film; In the step (1), the mass ratio of 3,3'-dibromo-4,4'-biphenol, 1,2,4,5-tetrabromobenzene, and potassium carbonate is 1:1.2 - 1.6:0.2 - 0.3; In the step (2), the mass ratio of intermediate 1, 4-aminophenylboronic acid, and triphenylphosphine palladium catalyst is 0.7 - 0.9:1:0.01 - 0.02; In the step (3), the mass fraction of solution A is 20 - 25%; The preparation method of the amino-functionalized multi-walled carbon nanotubes in the step (3) is as follows: Add multi-walled carbon nanotubes and p-nitrobenzoic acid into polyphosphoric acid, stir magnetically until evenly dispersed, then stir mechanically, then cool the temperature to 40 - 55 °C and add stannous chloride thereto to react for 2 - 4 h. After completion, cool to room temperature, wash with deionized water, and dry in vacuum to obtain amino-functionalized multi-walled carbon nanotubes; The mass ratio of the multi-walled carbon nanotubes, p-nitrobenzoic acid, polyphosphoric acid, and stannous chloride is 1:8 - 10:55 - 60:30 - 35; The temperature of the mechanical stirring is 115 - 125 °C; The time of the mechanical stirring is 1 - 2 h.

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